Science.gov

Sample records for aged model samples

  1. A dimensional liability model of age differences in mental disorder prevalence: evidence from a national sample.

    PubMed

    Hoertel, Nicolas; McMahon, Kibby; Olfson, Mark; Wall, Melanie M; Rodríguez-Fernández, Jorge Mario; Lemogne, Cédric; Limosin, Frédéric; Blanco, Carlos

    2015-05-01

    Recent theories have proposed a metastructure that organizes related mental disorders into broad dimensions of psychopathology (i.e., internalizing and externalizing dimensions). Prevalence rates of most mental disorders, when examined independently, are substantially lower in older than in younger adults, which may affect this metastructure. Within a nationally representative sample, the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC; N = 43,093), we developed a dimensional liability model of common psychiatric disorders to clarify whether aging affects specific disorders or general dimensions of psychopathology. Significant age differences existed across age groups (18-24, 25-34, 35-44, 45-54, 55-64, 65-75 and 75+), such that older adults showed lower prevalence rates of most disorders compared to younger adults. We next investigated patterns of disorder comorbidity for past-year psychiatric disorders and found that a distress-fear-externalizing liability model fit the data well. This model was age-group invariant and indicated that the observed lower prevalence of mental disorders with advancing age originates from lower average means on externalizing and internalizing liability dimensions. This unifying dimensional liability model of age and mental disorder comorbidity can help inform the role of aging on mental disorder prevalence for research and intervention efforts, and service planning for the impending crisis in geriatric mental health.

  2. Spectroscopic age and metallicity for a sample of Globular Clusters from Stellar Population Models

    NASA Astrophysics Data System (ADS)

    Stock, M. J.; Calderón, P.

    2009-05-01

    We present spectroscopic age and metallicity predictions for a sample of 20 Globular Clusters in the massive E0 galaxy NGC 1407 (data from Cenarro et al. 2007, AJ, 134, 391) and for the Galacic Globular Clusters data from the Library of Integrated Spectra of Galactic Globular Clusters (GGC's) from Schiavon et al. (2005, ApJS, 160, 163) including the widely studied 47 Tuc cluster. Using index-index plots we compared model Single Stellar Populations (SSP's) spectra to the integrated spectra of both samples of Globular Clusters using high resolution line strength indices (Stock, in prep.) and the syntethic SSP's models from P. Coelho (2007, private comm.) as well as the CB07 solar models. For the GC's in NGC1407, the predictions from the syntethic models's with [α /Fe]=0.4 are in good agreement with the results from Cenarro et al. (2007, AJ, 134, 391), taking into account that the dispersion is partially due to the fact that the mean [α/Fe] ratio of the sample is ≈ 0.3 dex, resulting in younger ages and lower metallicities (Thomas et al. 2003, A&A, 401, 429). We observe a bimodal distribution of the Fe4383+ index which is in turn an indicator of metallicity, also seen in Cenarro et al. (2005). The CB07 models predict ages that are widely spread over the plot yielding ages greater than 14 Gyrs. The metallicity derived from these models are very low for almost all the objects (Z < 0.008). The distribution of the GGC's on the syntethic model grid shows a trend in the sense that metal poor clusters are younger than metal rich ones, but this effect might not be real (de Angeli et al. 2005, AJ, 130, 116). For 47 Tuc we estimate an age of ≈ 10 Gyr, and metallicity Z < 0.011 (<[Fe/H]= -0.5) which are both comparable with the values reported in the literature (Carretta et al. 2000; Liu & Chaboyer 2000, ApJ, 544, 818; Schiavon et al. 2002, ApJ, 580, 873; Gratton et al. 2003, A&A, 408, 529).

  3. Circadian typology, age, and the alternative five-factor personality model in an adult women sample.

    PubMed

    Muro, Anna; Gomà-i-Freixanet, Montserrat; Adan, Ana; Cladellas, Ramon

    2011-10-01

    Research on personality and circadian typology indicates evening-type women are more impulsive and novelty seeking, neither types are more anxious, and morning types tend to be more active, conscientious, and persistent. The purpose of this study is to examine the differences between circadian typologies in the light of the Zuckerman's Alternative Five-Factor Model (AFFM) of personality, which has a strong biological basis, in an adult sample of 412 women 18 to 55 yrs of age. The authors found morning-type women had significant higher scores than evening-type and neither-type women on Activity, and its subscales General Activity and Work Activity. In contrast, evening-type women scored significantly higher than morning-type women on Aggression-Hostility, Impulsive Sensation Seeking, and its subscale Sensation Seeking. In all groups, results were independent of age. These findings are in accordance with those previously obtained in female student samples and add new data on the AFFM. The need of using personality models that are biologically based in the study of circadian rhythms is discussed.

  4. Developing a Comprehensive Model of Risk and Protective Factors That Can Predict Spelling at Age Seven: Findings from a Community Sample of Victorian Children

    ERIC Educational Resources Information Center

    Serry, Tanya Anne; Castles, Anne; Mensah, Fiona K.; Bavin, Edith L.; Eadie, Patricia; Pezic, Angela; Prior, Margot; Bretherton, Lesley; Reilly, Sheena

    2015-01-01

    The paper reports on a study designed to develop a risk model that can best predict single-word spelling in seven-year-old children when they were aged 4 and 5. Test measures, personal characteristics and environmental influences were all considered as variables from a community sample of 971 children. Strong concurrent correlations were found…

  5. Modeled ground water age distributions

    USGS Publications Warehouse

    Woolfenden, Linda R.; Ginn, Timothy R.

    2009-01-01

    The age of ground water in any given sample is a distributed quantity representing distributed provenance (in space and time) of the water. Conventional analysis of tracers such as unstable isotopes or anthropogenic chemical species gives discrete or binary measures of the presence of water of a given age. Modeled ground water age distributions provide a continuous measure of contributions from different recharge sources to aquifers. A numerical solution of the ground water age equation of Ginn (1999) was tested both on a hypothetical simplified one-dimensional flow system and under real world conditions. Results from these simulations yield the first continuous distributions of ground water age using this model. Complete age distributions as a function of one and two space dimensions were obtained from both numerical experiments. Simulations in the test problem produced mean ages that were consistent with the expected value at the end of the model domain for all dispersivity values tested, although the mean ages for the two highest dispersivity values deviated slightly from the expected value. Mean ages in the dispersionless case also were consistent with the expected mean ages throughout the physical model domain. Simulations under real world conditions for three dispersivity values resulted in decreasing mean age with increasing dispersivity. This likely is a consequence of an edge effect. However, simulations for all three dispersivity values tested were mass balanced and stable demonstrating that the solution of the ground water age equation can provide estimates of water mass density distributions over age under real world conditions.

  6. Modeled ground water age distributions.

    PubMed

    Woolfenden, Linda R; Ginn, Timothy R

    2009-01-01

    The age of ground water in any given sample is a distributed quantity representing distributed provenance (in space and time) of the water. Conventional analysis of tracers such as unstable isotopes or anthropogenic chemical species gives discrete or binary measures of the presence of water of a given age. Modeled ground water age distributions provide a continuous measure of contributions from different recharge sources to aquifers. A numerical solution of the ground water age equation of Ginn (1999) was tested both on a hypothetical simplified one-dimensional flow system and under real world conditions. Results from these simulations yield the first continuous distributions of ground water age using this model. Complete age distributions as a function of one and two space dimensions were obtained from both numerical experiments. Simulations in the test problem produced mean ages that were consistent with the expected value at the end of the model domain for all dispersivity values tested, although the mean ages for the two highest dispersivity values deviated slightly from the expected value. Mean ages in the dispersionless case also were consistent with the expected mean ages throughout the physical model domain. Simulations under real world conditions for three dispersivity values resulted in decreasing mean age with increasing dispersivity. This likely is a consequence of an edge effect. However, simulations for all three dispersivity values tested were mass balanced and stable demonstrating that the solution of the ground water age equation can provide estimates of water mass density distributions over age under real world conditions.

  7. High-Precision Plutonium Isotopic Compositions Measured on Los Alamos National Laboratory’s General’s Tanks Samples: Bearing on Model Ages, Reactor Modelling, and Sources of Material. Further Discussion of Chronometry

    SciTech Connect

    Spencer, Khalil J.; Rim, Jung Ho; Porterfield, Donivan R.; Roback, Robert Clifford; Boukhalfa, Hakim; Stanley, Floyd E.

    2015-06-29

    In this study, we re-analyzed late-1940’s, Manhattan Project era Plutonium-rich sludge samples recovered from the ''General’s Tanks'' located within the nation’s oldest Plutonium processing facility, Technical Area 21. These samples were initially characterized by lower accuracy, and lower precision mass spectrometric techniques. We report here information that was previously not discernable: the two tanks contain isotopically distinct Pu not only for the major (i.e., 240Pu, 239Pu) but trace (238Pu ,241Pu, 242Pu) isotopes. Revised isotopics slightly changed the calculated 241Am-241Pu model ages and interpretations.

  8. Petrology, chemistry, age and irradiation history of Luna 24 samples

    NASA Technical Reports Server (NTRS)

    Wasserburg, G. J.; Papanastassiou, D. A.; Mcculloch, M. T.; Huneke, J. C.; Dymek, R. F.; Depaolo, D. J.; Chodos, A. A.; Albee, A. L.; Radicati Di Brozolo, F.

    1978-01-01

    The results of petrological, chemical, isotopic age determination and irradiation studies of sample 24170 from the 170 cm depth of the regolith core returned from Mare Crisium by Luna 24 are presented. The sample is found to be comprised of fragments from a single igneous rock, with mineralogical evidence indicating it to be a mare basalt. The crystallization age is determined by Sm-Nd and Ar(40)-Ar(39) ages to be 3.30 AE, establishing the presence of relatively young flows. All soil samples show low trace element compositions with minimum contamination by KREEPUTh-rich materials. Rb-Sr and Sm-Nd relations reflect the absence of significant fractionation at ages younger than 4.5 AE. One soil sample shows extremely large neutron capture effects, imposing a new lower limit to the neutron production rate in the regolith and requiring the addition of irradiated materials from depth.

  9. ALL AGES LEAD MODEL

    EPA Science Inventory

    The Integrated Exposure Uptake Biokinetic (IEUBK) Model for Lead in Children (version 0.99d) was released in March 1994, and has been widely accepted in the risk assessment community as a tool for implementing the site specific risk assessment process when the issue is childhood...

  10. Aging Research Using Mouse Models.

    PubMed

    Ackert-Bicknell, Cheryl L; Anderson, Laura C; Sheehan, Susan; Hill, Warren G; Chang, Bo; Churchill, Gary A; Chesler, Elissa J; Korstanje, Ron; Peters, Luanne L

    2015-06-01

    Despite the dramatic increase in human lifespan over the past century, there remains pronounced variability in "health-span," or the period of time in which one is generally healthy and free of disease. Much of the variability in health-span and lifespan is thought to be genetic in origin. Understanding the genetic mechanisms of aging and identifying ways to boost longevity is a primary goal in aging research. Here, we describe a pipeline of phenotypic assays for assessing mouse models of aging. This pipeline includes behavior/cognition testing, body composition analysis, and tests of kidney function, hematopoiesis, and immune function, as well as physical parameters. We also describe study design methods for assessing lifespan and health-span, and other important considerations when conducting aging research in the laboratory mouse. The tools and assays provided can assist researchers with understanding the correlative relationships between age-associated phenotypes and, ultimately, the role of specific genes in the aging process.

  11. Aging Research Using Mouse Models

    PubMed Central

    Ackert-Bicknell, Cheryl L.; Anderson, Laura; Sheehan, Susan; Hill, Warren G.; Chang, Bo; Churchill, Gary A.; Chesler, Elissa J.; Korstanje, Ron; Peters, Luanne L.

    2015-01-01

    Despite the dramatic increase in human lifespan over the past century, there remains pronounced variability in “health-span”, or the period of time in which one is generally healthy and free of disease. Much of the variability in health-span and lifespan is thought to be genetic in origin. Understanding the genetic mechanisms of aging and identifying ways to boost longevity is a primary goal in aging research. Here, we describe a pipeline of phenotypic assays for assessing mouse models of aging. This pipeline includes behavior/cognition testing, body composition analysis, and tests of kidney function, hematopoiesis, immune function and physical parameters. We also describe study design methods for assessing lifespan and health-span, and other important considerations when conducting aging research in the laboratory mouse. The tools and assays provided can assist researchers with understanding the correlative relationships between age-associated phenotypes and, ultimately, the role of specific genes in the aging process. PMID:26069080

  12. Degradation process of lead chromate in paintings by Vincent van Gogh studied by means of spectromicroscopic methods. 4. Artificial aging of model samples of co-precipitates of lead chromate and lead sulfate.

    PubMed

    Monico, Letizia; Janssens, Koen; Miliani, Costanza; Van der Snickt, Geert; Brunetti, Brunetto Giovanni; Cestelli Guidi, Mariangela; Radepont, Marie; Cotte, Marine

    2013-01-15

    Previous investigations about the darkening of chrome yellow pigments revealed that this form of alteration is attributable to a reduction of the original Cr(VI) to Cr(III), and that the presence of sulfur-containing compounds, most often sulfates, plays a key role during this process. We recently demonstrated that different crystal forms of chrome yellow pigments (PbCrO(4) and PbCr(1-x)S(x)O(4)) are present in paintings by Vincent van Gogh. In the present work, we show how both the chemical composition and the crystalline structure of lead chromate-based pigments influence their stability. For this purpose, oil model samples made with in-house synthesized powders of PbCrO(4) and PbCr(1-x)S(x)O(4) were artificially aged and characterized. We observed a profound darkening only for those paint models made with PbCr(1-x)S(x)O(4), rich in SO(4)(2-) (x ≥ 0.4), and orthorhombic phases (>30 wt %). Cr and S K-edge micro X-ray absorption near edge structure investigations revealed in an unequivocal manner the formation of up to about 60% of Cr(III)-species in the outer layer of the most altered samples; conversely, independent of the paint models' chemical composition, no change in the S-oxidation state was observed. Analyses employing UV-visible diffuse reflectance and Fourier transform infrared spectroscopy were performed on unaged and aged model samples in order to obtain additional information on the physicochemical changes induced by the aging treatment.

  13. Differential Prediction of Alcohol vs. Hard Drug Use Levels in a General Youth Sample via the HEW Youth Development Model's Community Youth Program Impact Scales, Age, and Sex.

    ERIC Educational Resources Information Center

    Truckenmiller, James L.

    Recent national surveys have found marked increases in the use of illicit drugs and alcohol among adolescents. To investigate differential prediction of alcohol versus hard drug use amoung youths, 6% of the youths, aged 10-19, from a Pennsylvania county school system (N=1,689) were assessed on the HEW Community Youth Program Impact Scales. The 12…

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

    PubMed

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

    2016-02-01

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

  15. Absolute ages from crater statistics: Using radiometric ages of Martian samples for determining the Martian cratering chronology

    NASA Technical Reports Server (NTRS)

    Neukum, G.

    1988-01-01

    In the absence of dates derived from rock samples, impact crater frequencies are commonly used to date Martian surface units. All models for absolute dating rely on the lunar cratering chronology and on the validity of its extrapolation to Martian conditions. Starting from somewhat different lunar chronologies, rather different Martian cratering chronologies are found in the literature. Currently favored models are compared. The differences at old ages are significant, the differences at younger ages are considerable and give absolute ages for the same crater frequencies as different as a factor of 3. The total uncertainty could be much higher, though, since the ratio of lunar to Martian cratering rate which is of basic importance in the models is believed to be known no better than within a factor of 2. Thus, it is of crucial importance for understanding the the evolution of Mars and determining the sequence of events to establish an unambiguous Martian cratering chronology from crater statistics in combination with clean radiometric ages of returned Martian samples. For the dating goal, rocks should be as pristine as possible from a geologically simple area with a one-stage emplacement history of the local formation. A minimum of at least one highland site for old ages, two intermediate-aged sites, and one very young site is needed.

  16. Improved age determination of blood and teeth samples using a selected set of DNA methylation markers

    PubMed Central

    Kamalandua, Aubeline

    2015-01-01

    Age estimation from DNA methylation markers has seen an exponential growth of interest, not in the least from forensic scientists. The current published assays, however, can still be improved by lowering the number of markers in the assay and by providing more accurate models to predict chronological age. From the published literature we selected 4 age-associated genes (ASPA, PDE4C, ELOVL2, and EDARADD) and determined CpG methylation levels from 206 blood samples of both deceased and living individuals (age range: 0–91 years). This data was subsequently used to compare prediction accuracy with both linear and non-linear regression models. A quadratic regression model in which the methylation levels of ELOVL2 were squared showed the highest accuracy with a Mean Absolute Deviation (MAD) between chronological age and predicted age of 3.75 years and an adjusted R2 of 0.95. No difference in accuracy was observed for samples obtained either from living and deceased individuals or between the 2 genders. In addition, 29 teeth from different individuals (age range: 19–70 years) were analyzed using the same set of markers resulting in a MAD of 4.86 years and an adjusted R2 of 0.74. Cross validation of the results obtained from blood samples demonstrated the robustness and reproducibility of the assay. In conclusion, the set of 4 CpG DNA methylation markers is capable of producing highly accurate age predictions for blood samples from deceased and living individuals PMID:26280308

  17. [Experimental models of human skin aging].

    PubMed

    Nikolakis, G; Zoschke, C; Makrantonaki, E; Hausmann, C; Schäfer-Korting, M; Zouboulis, C C

    2016-02-01

    The skin is a representative model for the study of human aging. Despite the high regenerative capacity of the skin, skin physiology changes over the course of life. Medical and cosmetic research is trying to prevent aging, to slow, to stop, or to reverse it. Effects of age-related DNA damage and of changing skin structure on pharmacological parameters are largely unknown. This review article summarizes the state of scientific knowledge in the field of experimental models of human skin aging and shows approaches to improve organotypic skin models, to develop predictive models of aging, and improve aging research.

  18. Modeling abundance effects in distance sampling

    USGS Publications Warehouse

    Royle, J. Andrew; Dawson, D.K.; Bates, S.

    2004-01-01

    Distance-sampling methods are commonly used in studies of animal populations to estimate population density. A common objective of such studies is to evaluate the relationship between abundance or density and covariates that describe animal habitat or other environmental influences. However, little attention has been focused on methods of modeling abundance covariate effects in conventional distance-sampling models. In this paper we propose a distance-sampling model that accommodates covariate effects on abundance. The model is based on specification of the distance-sampling likelihood at the level of the sample unit in terms of local abundance (for each sampling unit). This model is augmented with a Poisson regression model for local abundance that is parameterized in terms of available covariates. Maximum-likelihood estimation of detection and density parameters is based on the integrated likelihood, wherein local abundance is removed from the likelihood by integration. We provide an example using avian point-transect data of Ovenbirds (Seiurus aurocapillus) collected using a distance-sampling protocol and two measures of habitat structure (understory cover and basal area of overstory trees). The model yields a sensible description (positive effect of understory cover, negative effect on basal area) of the relationship between habitat and Ovenbird density that can be used to evaluate the effects of habitat management on Ovenbird populations.

  19. Tissue Sampling Guides for Porcine Biomedical Models.

    PubMed

    Albl, Barbara; Haesner, Serena; Braun-Reichhart, Christina; Streckel, Elisabeth; Renner, Simone; Seeliger, Frank; Wolf, Eckhard; Wanke, Rüdiger; Blutke, Andreas

    2016-04-01

    This article provides guidelines for organ and tissue sampling adapted to porcine animal models in translational medical research. Detailed protocols for the determination of sampling locations and numbers as well as recommendations on the orientation, size, and trimming direction of samples from ∼50 different porcine organs and tissues are provided in the Supplementary Material. The proposed sampling protocols include the generation of samples suitable for subsequent qualitative and quantitative analyses, including cryohistology, paraffin, and plastic histology; immunohistochemistry;in situhybridization; electron microscopy; and quantitative stereology as well as molecular analyses of DNA, RNA, proteins, metabolites, and electrolytes. With regard to the planned extent of sampling efforts, time, and personnel expenses, and dependent upon the scheduled analyses, different protocols are provided. These protocols are adjusted for (I) routine screenings, as used in general toxicity studies or in analyses of gene expression patterns or histopathological organ alterations, (II) advanced analyses of single organs/tissues, and (III) large-scale sampling procedures to be applied in biobank projects. Providing a robust reference for studies of porcine models, the described protocols will ensure the efficiency of sampling, the systematic recovery of high-quality samples representing the entire organ or tissue as well as the intra-/interstudy comparability and reproducibility of results.

  20. Aging Successfully: A Four-Factor Model

    ERIC Educational Resources Information Center

    Lee, Pai-Lin; Lan, William; Yen, Tung-Wen

    2011-01-01

    The study was designed to validate a model for a successful aging process and examine the gender differences in the aging process. Three hundred twelve participants who were 65 or older completed a Taiwan Social Change Survey that measures four factors that define successful aging process: including physical, psychological, social support, and…

  1. Modelling the molecular mechanisms of aging.

    PubMed

    Mc Auley, Mark T; Guimera, Alvaro Martinez; Hodgson, David; Mcdonald, Neil; Mooney, Kathleen M; Morgan, Amy E; Proctor, Carole J

    2017-02-28

    The aging process is driven at the cellular level by random molecular damage that slowly accumulates with age. Although cells possess mechanisms to repair or remove damage, they are not 100% efficient and their efficiency declines with age. There are many molecular mechanisms involved and exogenous factors such as stress also contribute to the aging process. The complexity of the aging process has stimulated the use of computational modelling in order to increase our understanding of the system, test hypotheses and make testable predictions. As many different mechanisms are involved, a wide range of models have been developed. This paper gives an overview of the types of models that have been developed, the range of tools used, modelling standards and discusses many specific examples of models that have been grouped according to the main mechanisms that they address. We conclude by discussing the opportunities and challenges for future modelling in this field.

  2. Modelling the molecular mechanisms of aging

    PubMed Central

    Mc Auley, Mark T.; Guimera, Alvaro Martinez; Hodgson, David; Mcdonald, Neil; Mooney, Kathleen M.; Morgan, Amy E.

    2017-01-01

    The aging process is driven at the cellular level by random molecular damage that slowly accumulates with age. Although cells possess mechanisms to repair or remove damage, they are not 100% efficient and their efficiency declines with age. There are many molecular mechanisms involved and exogenous factors such as stress also contribute to the aging process. The complexity of the aging process has stimulated the use of computational modelling in order to increase our understanding of the system, test hypotheses and make testable predictions. As many different mechanisms are involved, a wide range of models have been developed. This paper gives an overview of the types of models that have been developed, the range of tools used, modelling standards and discusses many specific examples of models that have been grouped according to the main mechanisms that they address. We conclude by discussing the opportunities and challenges for future modelling in this field. PMID:28096317

  3. 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.

  4. The Gilded Age: An ERIC/ChESS Sample.

    ERIC Educational Resources Information Center

    Kelly, David

    1999-01-01

    Provides a list of teaching materials and general background information from the ERIC database on the Gilded Age and directions for obtaining the full text of these materials; topics include, but are not limited to, immigration, the 1896 presidential election, the Populist movement, the Industrial Revolution, urbanization, and the development of…

  5. Aging and Sexuality: Perceptions of a Puerto Rican Sample.

    ERIC Educational Resources Information Center

    Waters, Judith; Drew, Benjamin

    While there are acknowledged physical, psychological, and social benefits to be derived from maintaining sexual activity in old age, the negative cultural attitudes displayed by younger members of society as well as by their own peers constitute a barrier to the achievement of a satisfactory sex life for the elderly. A study was undertaken to…

  6. [Deafness and aging: studies in experimental models].

    PubMed

    Gil Loyzaga, Pablo E

    2002-01-01

    Since 1970 a progressive aging of the world population, mainly in the most developed countries, has been observed. Spain could have, around 2050, the most aged human population of the world. Therefore, scientist show an increasing interest on the study of the aging-related pathologies (i.e. deafness linked to aging process: presbycusis). The deep analysis of the presbycusis physiopathology will be based on the study of patients, but also on animal models. This report summarizes our results obtained on the analysis of the deafness linked to aging on the C57/BL/6 mice.

  7. Mouse models and aging: longevity and progeria.

    PubMed

    Liao, Chen-Yu; Kennedy, Brian K

    2014-01-01

    Aging is a complex, multifactorial process that is likely influenced by the activities of a range of biological pathways. Genetic approaches to identify genes modulating longevity have been highly successful and recent efforts have extended these studies to mammalian aging. A variety of genetic models have been reported to have enhanced lifespan and, similarly, many genetic interventions lead to progeroid phenotypes. Here, we detail and evaluate both sets of models, focusing on the insights they provide about the molecular processes modulating aging and the extent to which mutations conferring progeroid pathologies really phenocopy accelerated aging.

  8. Modeling abundance using hierarchical distance sampling

    USGS Publications Warehouse

    Royle, Andy; Kery, Marc

    2016-01-01

    In this chapter, we provide an introduction to classical distance sampling ideas for point and line transect data, and for continuous and binned distance data. We introduce the conditional and the full likelihood, and we discuss Bayesian analysis of these models in BUGS using the idea of data augmentation, which we discussed in Chapter 7. We then extend the basic ideas to the problem of hierarchical distance sampling (HDS), where we have multiple point or transect sample units in space (or possibly in time). The benefit of HDS in practice is that it allows us to directly model spatial variation in population size among these sample units. This is a preeminent concern of most field studies that use distance sampling methods, but it is not a problem that has received much attention in the literature. We show how to analyze HDS models in both the unmarked package and in the BUGS language for point and line transects, and for continuous and binned distance data. We provide a case study of HDS applied to a survey of the island scrub-jay on Santa Cruz Island, California.

  9. Age Differences in Personality: Evidence from a Nationally Representative Australian Sample

    ERIC Educational Resources Information Center

    Lucas, Richard E.; Donnellan, M. Brent

    2009-01-01

    Cross-sectional age differences in the Big Five personality traits were examined in a nationally representative sample of Australians (N = 12,618; age range = 15-84). Extraversion, Neuroticism, and Openness were negatively associated with age, whereas Agreeableness and Conscientiousness were positively associated with age. Effect sizes comparing…

  10. Mixture models for distance sampling detection functions.

    PubMed

    Miller, David L; Thomas, Len

    2015-01-01

    We present a new class of models for the detection function in distance sampling surveys of wildlife populations, based on finite mixtures of simple parametric key functions such as the half-normal. The models share many of the features of the widely-used "key function plus series adjustment" (K+A) formulation: they are flexible, produce plausible shapes with a small number of parameters, allow incorporation of covariates in addition to distance and can be fitted using maximum likelihood. One important advantage over the K+A approach is that the mixtures are automatically monotonic non-increasing and non-negative, so constrained optimization is not required to ensure distance sampling assumptions are honoured. We compare the mixture formulation to the K+A approach using simulations to evaluate its applicability in a wide set of challenging situations. We also re-analyze four previously problematic real-world case studies. We find mixtures outperform K+A methods in many cases, particularly spiked line transect data (i.e., where detectability drops rapidly at small distances) and larger sample sizes. We recommend that current standard model selection methods for distance sampling detection functions are extended to include mixture models in the candidate set.

  11. Probabilistically Constraining Age-Depth-Models of Glaciogenic Sediments

    NASA Astrophysics Data System (ADS)

    Werner, J.; van der Bilt, W.; Tingley, M.

    2015-12-01

    Reconstructions of the late-Holocene climate rely heavily upon proxies that are assumed to be accurately dated by layer counting. All of these proxies, such as measurements of tree rings, ice cores, and varved lake sediments do carry some inherent dating uncertainty that is not always fully accounted for. Considerable advances could be achieved if time uncertainties were recognized and correctly modeled, also for proxies commonly treated as free of age model errors. Current approaches for accounting for time uncertainty are generally limited to repeating the reconstruction using each one of an ensemble of age models, thereby inflating the final estimated uncertainty - in effect, each possible age model is given equal weighting. Uncertainties can be reduced by exploiting the inferred space-time covariance structure of the climate to re-weight the possible age models. Werner and Tingley (2015) demonstrated how Bayesian hierarchical climate reconstruction models can be augmented to account for time-uncertain proxies. In their method, probabilities associated with the age models are formally updated within the Bayesian framework, thereby reducing uncertainties. Numerical experiments (Werner and Tingley 2015) show that updating the age model probabilities decreases uncertainty in the resulting reconstructions, as compared with the current de facto standard of sampling over all age models, provided there is sufficient information from other data sources in the spatial region of the time-uncertain proxy. We show how this novel method can be applied to high resolution, sub-annually sampled lacustrine sediment records to constrain their respective age depth models. The results help to quantify the signal content and extract the regionally representative signal. The single time series can then be used as the basis for a reconstruction of glacial activity. van der Bilt et al. in prep. Werner, J.P. and Tingley, M.P. Clim. Past (2015)

  12. The Penna Model of Biological Aging

    PubMed Central

    Stauffer, D.

    2007-01-01

    This review deals with computer simulation of biological aging, particularly with the Penna model of 1995. They are based on the mutation accumulation theory of half a century ago. The results agree well with demographical reality, and also with the seemingly contradictory influence of predators on the aging of prey. PMID:20066128

  13. Annealed Importance Sampling for Neural Mass Models

    PubMed Central

    Penny, Will; Sengupta, Biswa

    2016-01-01

    Neural Mass Models provide a compact description of the dynamical activity of cell populations in neocortical regions. Moreover, models of regional activity can be connected together into networks, and inferences made about the strength of connections, using M/EEG data and Bayesian inference. To date, however, Bayesian methods have been largely restricted to the Variational Laplace (VL) algorithm which assumes that the posterior distribution is Gaussian and finds model parameters that are only locally optimal. This paper explores the use of Annealed Importance Sampling (AIS) to address these restrictions. We implement AIS using proposals derived from Langevin Monte Carlo (LMC) which uses local gradient and curvature information for efficient exploration of parameter space. In terms of the estimation of Bayes factors, VL and AIS agree about which model is best but report different degrees of belief. Additionally, AIS finds better model parameters and we find evidence of non-Gaussianity in their posterior distribution. PMID:26942606

  14. Fitting models to correlated data (large samples)

    NASA Astrophysics Data System (ADS)

    Féménias, Jean-Louis

    2004-03-01

    The study of the ordered series of residuals of a fit proved to be useful in evaluating separately the pure experimental error and the model bias leading to a possible improvement of the modeling [J. Mol. Spectrosc. 217 (2003) 32]. In the present work this procedure is extended to homogeneous correlated data. This new method allows a separate estimation of pure experimental error, model bias, and data correlation; furthermore, it brings a new insight into the difference between goodness of fit and model relevance. It can be considered either as a study of 'random systematic errors' or as an extended approach of the Durbin-Watson problem [Biometrika 37 (1950) 409] taking into account the model error. In the present work an empirical approach is proposed for large samples ( n⩾500) where numerical tests are done showing the accuracy and the limits of the method.

  15. Latin hypercube sampling with the SESOIL model

    SciTech Connect

    Hetrick, D.M.; Luxmoore, R.J.; Tharp, M.L.

    1994-09-01

    The seasonal soil compartment model SESOIL, a one-dimensional vertical transport code for chemicals in the unsaturated soil zone, has been coupled with the Monte Carlo computer code PRISM, which utilizes a Latin hypercube sampling method. Frequency distributions are assigned to each of 64 soil, chemical, and climate input variables for the SESOIL model, and these distributions are randomly sampled to generate N (200, for example) input data sets. The SESOIL model is run by PRISM for each set of input values, and the combined set of model variables and predictions are evaluated statistically by PRISM to summarize the relative influence of input variables on model results. Output frequency distributions for selected SESOIL components are produced. As an initial analysis and to illustrate the PRISM/SESOIL approach, input data were compiled for the model for three sites at different regions of the country (Oak Ridge, Tenn.; Fresno, Calif.; Fargo, N.D.). The chemical chosen for the analysis was trichloroethylene (TCE), which was initially loaded in the soil column at a 60- to 90-cm depth. The soil type at each site was assumed to be identical to the cherty silt loam at Oak Ridge; the only difference in the three data sets was the climatic data. Output distributions for TCE mass flux volatilized, TCE mass flux to groundwater, and residual TCE concentration in the lowest soil layer are vastly different for the three sites.

  16. Using GC × GC-FID profiles to estimate the age of weathered gasoline samples.

    PubMed

    Zorzetti, Brianne M; Harynuk, James J

    2011-11-01

    Predicting the amount of time that a petroleum mixture has been exposed to weathering effects has applications in areas of environmental and other forensic investigations, such as aiding in determining the cause and intent of a fire. Historically, research on the evaporation rates of hydrocarbon mixtures has focused on forensic oil spill identification and predicting if a fresh sample could be weathered to give an observed composition in an aged sample. Relatively little attention has focused on approaching the problem from the other direction: estimating exposure time based on the observed composition of a weathered sample at a given time and assuming a prior composition. Here, we build upon our previous research into the weathering of model mixtures by extending our work to gasoline. Samples of gasoline with varying octane ratings and from several vendors were weathered under controlled conditions and their composition monitored over time by two-dimensional gas chromatography (GC × GC). A variety of chemometric models were explored, including partial least squares (PLS), nonlinear PLS (PolyPLS) and locally weighted regression (LWR). A hierarchical application of multivariate techniques was able to predict the time for which a sample had been exposed to evaporative weathering. Partial least squares discriminant analysis could predict whether a sample was relatively fresh (<12 h exposure time) or highly weathered (>20 h exposure time). Subsequent regression models for these classes were evaluated for accuracy using the root mean square error of prediction. LWR was the most successful, whereby fresh and highly weathered samples were predicted to within 30 min and 5 h of exposure, respectively.

  17. A Model of Spirituality for Ageing Muslims.

    PubMed

    Ahmad, Mahjabeen; Khan, Shamsul

    2016-06-01

    Spirituality's influence on general well-being and its association with healthy ageing has been studied extensively. However, a different perspective has to be brought in when dealing with spirituality issues of ageing Muslims. Central to this perspective is the intertwining of religion and spirituality in Islam. This article will contribute to the understanding of the nature of Islamic spirituality and its immense importance in the life of a practicing ageing Muslim. Consequently, it will help care providers to include appropriate spiritual care in the care repertoire of a Muslim care recipient. It is assumed that the framework for a model of spirituality based on Islamic religious beliefs would help contextualise the relationship between spirituality and ageing Muslims. Not only challenges, but also the opportunities that old age provides for charting the spiritual journey have underpinned this model.

  18. Childhood Trauma Questionnaire (CTQ) in Brazilian Samples of Different Age Groups: Findings from Confirmatory Factor Analysis

    PubMed Central

    Grassi-Oliveira, Rodrigo; Cogo-Moreira, Hugo; Salum, Giovanni Abrahão; Brietzke, Elisa; Viola, Thiago Wendt; Manfro, Gisele Gus; Kristensen, Christian Haag; Arteche, Adriane Xavier

    2014-01-01

    The Childhood Trauma Questionnaire (CTQ) is internationally accepted as a key tool for the assessment of childhood abuse and neglect experiences. However, there are relative few psychometric studies available and some authors have proposed two different factor solutions. We examined the dimensional structure and internal consistency of the Brazilian version of the CTQ. A total of 1,925 participants from eight different clinical and non-clinical samples including adolescents, adults and elders were considered in this study. First, we performed Confirmatory Factor Analysis to investigate the goodness of fit of the two proposed competitive factor structure models for the CTQ. We also investigated the internal consistency of all factors. Second, multi-group analyses were used to investigate measurement invariance and population heterogeneity across age groups and sex. Our findings revealed that the alternative factor structure as opposed to the original factor structure was the most appropriate model within adolescents and adults Brazilian samples. We provide further evidence for the validity and reliability of the CTQ within the Brazilian samples and report that the alternative model showed an improvement in fit indexes and may be a better alternative over the original model. PMID:24475237

  19. Reduced sampling efficiency causes degraded Vernier hyperacuity with normal aging: Vernier acuity in position noise.

    PubMed

    Li, Roger W; Brown, Brian; Edwards, Marion H; Ngo, Charlie V; Chat, Sandy W; Levi, Dennis M

    2012-01-01

    Vernier acuity, a form of visual hyperacuity, is amongst the most precise forms of spatial vision. Under optimal conditions Vernier thresholds are much finer than the inter-photoreceptor distance. Achievement of such high precision is based substantially on cortical computations, most likely in the primary visual cortex. Using stimuli with added positional noise, we show that Vernier processing is reduced with advancing age across a wide range of noise levels. Using an ideal observer model, we are able to characterize the mechanisms underlying age-related loss, and show that the reduction in Vernier acuity can be mainly attributed to the reduction in efficiency of sampling, with no significant change in the level of internal position noise, or spatial distortion, in the visual system.

  20. Predicting successful aging in a population-based sample of georgia centenarians.

    PubMed

    Arnold, Jonathan; Dai, Jianliang; Nahapetyan, Lusine; Arte, Ankit; Johnson, Mary Ann; Hausman, Dorothy; Rodgers, Willard L; Hensley, Robert; Martin, Peter; Macdonald, Maurice; Davey, Adam; Siegler, Ilene C; Jazwinski, S Michal; Poon, Leonard W

    2010-01-01

    Used a population-based sample (Georgia Centenarian Study, GCS), to determine proportions of centenarians reaching 100 years as (1) survivors (43%) of chronic diseases first experienced between 0-80 years of age, (2) delayers (36%) with chronic diseases first experienced between 80-98 years of age, or (3) escapers (17%) with chronic diseases only at 98 years of age or older. Diseases fall into two morbidity profiles of 11 chronic diseases; one including cardiovascular disease, cancer, anemia, and osteoporosis, and another including dementia. Centenarians at risk for cancer in their lifetime tended to be escapers (73%), while those at risk for cardiovascular disease tended to be survivors (24%), delayers (39%), or escapers (32%). Approximately half (43%) of the centenarians did not experience dementia. Psychiatric disorders were positively associated with dementia, but prevalence of depression, anxiety, and psychoses did not differ significantly between centenarians and an octogenarian control group. However, centenarians were higher on the Geriatric Depression Scale (GDS) than octogenarians. Consistent with our model of developmental adaptation in aging, distal life events contribute to predicting survivorship outcome in which health status as survivor, delayer, or escaper appears as adaptation variables late in life.

  1. Species ages in neutral biodiversity models.

    PubMed

    Chisholm, Ryan A; O'Dwyer, James P

    2014-05-01

    Biogeography seeks to understand the mechanisms that drive biodiversity across long temporal and large spatial scales. Theoretical models of biogeography can be tested by comparing their predictions of quantities such as species ages against empirical estimates. It has previously been claimed that the neutral theory of biodiversity and biogeography predicts species ages that are unrealistically long. Any improved theory of biodiversity must rectify this problem, but first it is necessary to quantify the problem precisely. Here we provide analytical expressions for species ages in neutral biodiversity communities. We analyse a spatially implicit metacommunity model and solve for both the zero-sum and non-zero-sum cases. We explain why our new expressions are, in the context of biodiversity, usually more appropriate than those previously imported from neutral molecular evolution. Because of the time symmetry of the spatially implicit neutral model, our expressions also lead directly to formulas for species persistence times and species lifetimes. We use our new expressions to estimate species ages of forest trees under a neutral model and find that they are about an order of magnitude shorter than those predicted previously but still unrealistically long. In light of our results, we discuss different models of biogeography that may solve the problem of species ages.

  2. Accuracy of the estimation of dental age in comparison with chronological age in a Spanish sample of 2641 living subjects using the Demirjian and Nolla methods.

    PubMed

    Melo, María; Ata-Ali, Javier

    2017-01-01

    Age estimation is an important procedure in forensic medicine and is carried out for a number of reasons. For living persons, age estimation is performed in order to assess whether a child has attained the age of criminal responsibility, in scenarios involving rape, kidnapping or marriage, in premature births, adoption procedures, illegal immigration, pediatric endocrine diseases and orthodontic malocclusion, as well as in circumstances in which the birth certificate is not available or the records are suspect. According to data from the UNHCR (United Nations High Commissioner for Refugees), the number of people seeking refugee status continued to increase in the last years, driven by the wars in Syria and Iraq, as well as by conflict and instability in Afghanistan, Eritrea and elsewhere. The objective of this study is to compare the accuracy of estimating dental age versus chronological age using the Nolla and Demirjian methods in a Spanish population. A final sample of 2641 panoramic X-rays corresponding to Spanish patients (1322 males and 1319 females) between 7-21 years of age was analyzed. Dental age was assessed using the Nolla and Demirjian methods, establishing comparisons with mean chronological age based on the Student t-test for paired samples, followed by the generation of a linear regression model. Both methods showed slight discrepancy between dental and chronological age. On examining the reproducibility of the Nolla and Demirjian methods, technical errors of 0.84% and 0.62%, respectively, were observed. On average, the Nolla method was found to estimate an age 0.213years younger than the chronological age, while the Demirjian method estimated an age 0.853years older than the chronological age. Linear combination of the mean Nolla and Demirjian estimates increased the predictive capacity to 99.2%. In conclusion the Nolla and Demirjian methods were found to be accurate in estimating chronological age from dental age in a Spanish population. The error

  3. Active Ageing: An Empirical Approach to the WHO Model

    PubMed Central

    Paúl, Constança; Ribeiro, Oscar; Teixeira, Laetitia

    2012-01-01

    Background. In the beginning of the 21st century, the world summit on population taking place in Madrid approved active ageing, WHO (2002) as the main objective of health and social policies for old people. Few studies have been done on the scientific validity of the construct. This study aims to validate the construct of active ageing and test empirically the WHO (2002) model of Active Ageing in a sample of community-dwelling seniors. Methods. 1322 old people living in the community were interviewed using an extensive assessment protocol to measure WHO's determinants of active ageing and performed an exploratory factor analysis followed by a confirmatory factor analyses. Results. We did not confirm the active ageing model, as most of the groups of determinants are either not independent or not significant. We got to a six-factor model (health, psychological component, cognitive performance, social relationships, biobehavioural component, and personality) explaining 54.6% of total variance. Conclusion. The present paper shows that there are objective as well as subjective variables contributing to active ageing and that psychological variables seem to give a very important contribute to the construct. The profile of active ageing is expected to vary between contexts and cultures and can be used to guide specific community and individually based interventions. PMID:23193396

  4. Love Kills:. Simulations in Penna Ageing Model

    NASA Astrophysics Data System (ADS)

    Stauffer, Dietrich; Cebrat, Stanisław; Penna, T. J. P.; Sousa, A. O.

    The standard Penna ageing model with sexual reproduction is enlarged by adding additional bit-strings for love: Marriage happens only if the male love strings are sufficiently different from the female ones. We simulate at what level of required difference the population dies out.

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

    PubMed

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

    2015-03-01

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

  6. Trajectories of HIV Risk Behavior from Age 15 to 25 in the National Longitudinal Survey of Youth Sample

    ERIC Educational Resources Information Center

    Murphy, Debra A.; Brecht, Mary-Lynn; Herbeck, Diane M.; Huang, David

    2009-01-01

    This study utilized data from the National Longitudinal Survey of Youth to investigate youth risk trajectories for HIV and factors associated with different trajectories. The sample (N = 8,208) was 49.2% female, with a mean age of 14.31 (SD = 1.48). A group-based trajectory model was applied, which identified four distinct trajectories for both…

  7. Normal brain ageing: models and mechanisms

    PubMed Central

    Toescu, Emil C

    2005-01-01

    Normal ageing is associated with a degree of decline in a number of cognitive functions. Apart from the issues raised by the current attempts to expand the lifespan, understanding the mechanisms and the detailed metabolic interactions involved in the process of normal neuronal ageing continues to be a challenge. One model, supported by a significant amount of experimental evidence, views the cellular ageing as a metabolic state characterized by an altered function of the metabolic triad: mitochondria–reactive oxygen species (ROS)–intracellular Ca2+. The perturbation in the relationship between the members of this metabolic triad generate a state of decreased homeostatic reserve, in which the aged neurons could maintain adequate function during normal activity, as demonstrated by the fact that normal ageing is not associated with widespread neuronal loss, but become increasingly vulnerable to the effects of excessive metabolic loads, usually associated with trauma, ischaemia or neurodegenerative processes. This review will concentrate on some of the evidence showing altered mitochondrial function with ageing and also discuss some of the functional consequences that would result from such events, such as alterations in mitochondrial Ca2+ homeostasis, ATP production and generation of ROS. PMID:16321805

  8. Probabilistically constraining proxy age-depth models within a Bayesian hierarchical reconstruction model

    NASA Astrophysics Data System (ADS)

    Werner, Johannes; Tingley, Martin

    2015-04-01

    Reconstructions of late-Holocene climate rely heavily upon proxies that are assumed to be accurately dated by layer counting, such as measurement on tree rings, ice cores, and varved lake sediments. Considerable advances may be achievable if time uncertain proxies could be included within these multiproxy reconstructions, and if time uncertainties were recognized and correctly modeled for proxies commonly treated as free of age model errors. Current approaches to accounting for time uncertainty are generally limited to repeating the reconstruction using each of an ensemble of age models, thereby inflating the final estimated uncertainty - in effect, each possible age model is given equal weighting. Uncertainties can be reduced by exploiting the inferred space-time covariance structure of the climate to re-weight the possible age models. Here we demonstrate how Bayesian Hierarchical climate reconstruction models can be augmented to account for time uncertain proxies. Critically, while a priori all age models are given equal probability of being correct, the probabilities associated with the age models are formally updated within the Bayesian framework, thereby reducing uncertainties. Numerical experiments show that updating the age model probabilities decreases uncertainty in the climate reconstruction, as compared with the current de-facto standard of sampling over all age models, provided there is sufficient information from other data sources in the region of the time-uncertain proxy. This approach can readily be generalized to non-layer counted proxies, such as those derived from marine sediments. Werner and Tingley, Climate of the Past Discussions (2014)

  9. Technical Note: Probabilistically constraining proxy age-depth models within a Bayesian hierarchical reconstruction model

    NASA Astrophysics Data System (ADS)

    Werner, J. P.; Tingley, M. P.

    2015-03-01

    Reconstructions of the late-Holocene climate rely heavily upon proxies that are assumed to be accurately dated by layer counting, such as measurements of tree rings, ice cores, and varved lake sediments. Considerable advances could be achieved if time-uncertain proxies were able to be included within these multiproxy reconstructions, and if time uncertainties were recognized and correctly modeled for proxies commonly treated as free of age model errors. Current approaches for accounting for time uncertainty are generally limited to repeating the reconstruction using each one of an ensemble of age models, thereby inflating the final estimated uncertainty - in effect, each possible age model is given equal weighting. Uncertainties can be reduced by exploiting the inferred space-time covariance structure of the climate to re-weight the possible age models. Here, we demonstrate how Bayesian hierarchical climate reconstruction models can be augmented to account for time-uncertain proxies. Critically, although a priori all age models are given equal probability of being correct, the probabilities associated with the age models are formally updated within the Bayesian framework, thereby reducing uncertainties. Numerical experiments show that updating the age model probabilities decreases uncertainty in the resulting reconstructions, as compared with the current de facto standard of sampling over all age models, provided there is sufficient information from other data sources in the spatial region of the time-uncertain proxy. This approach can readily be generalized to non-layer-counted proxies, such as those derived from marine sediments.

  10. Technical Note: Probabilistically constraining proxy age-depth models within a Bayesian hierarchical reconstruction model

    NASA Astrophysics Data System (ADS)

    Werner, J. P.; Tingley, M. P.

    2014-12-01

    Reconstructions of late-Holocene climate rely heavily upon proxies that are assumed to be accurately dated by layer counting, such as measurement on tree rings, ice cores, and varved lake sediments. Considerable advances may be achievable if time uncertain proxies could be included within these multiproxy reconstructions, and if time uncertainties were recognized and correctly modeled for proxies commonly treated as free of age model errors. Current approaches to accounting for time uncertainty are generally limited to repeating the reconstruction using each of an ensemble of age models, thereby inflating the final estimated uncertainty - in effect, each possible age model is given equal weighting. Uncertainties can be reduced by exploiting the inferred space-time covariance structure of the climate to re-weight the possible age models. Here we demonstrate how Bayesian Hierarchical climate reconstruction models can be augmented to account for time uncertain proxies. Critically, while a priori all age models are given equal probability of being correct, the probabilities associated with the age models are formally updated within the Bayesian framework, thereby reducing uncertainties. Numerical experiments show that updating the age-model probabilities decreases uncertainty in the climate reconstruction, as compared with the current de-facto standard of sampling over all age models, provided there is sufficient information from other data sources in the region of the time-uncertain proxy. This approach can readily be generalized to non-layer counted proxies, such as those derived from marine sediments.

  11. In situ UV monitoring of wastewater: a response to sample aging.

    PubMed

    Baurès, E; Berho, C; Pouet, M F; Thomas, O

    2004-01-01

    The phenomenon of wastewater sample aging is supposed to be treated with a low temperature autosampler. This work presents two examples of treated wastewater, the quality of which varies with the time of conservation. This evolution may pose some problems with respect to regulation compliance or process control. After the explanation of the mechanisms involved in sample aging, some recommendations are proposed in order to improve the UV off-line measurement of TSS and COD of treated wastewater.

  12. Cellular Aging and Restorative Processes: Subjective Sleep Quality and Duration Moderate the Association between Age and Telomere Length in a Sample of Middle-Aged and Older Adults

    PubMed Central

    Cribbet, Matthew R.; Carlisle, McKenzie; Cawthon, Richard M.; Uchino, Bert N.; Williams, Paula G.; Smith, Timothy W.; Gunn, Heather E.; Light, Kathleen C.

    2014-01-01

    telomere length in a sample of middle-aged and older adults. SLEEP 2014;37(1):65-70. PMID:24470696

  13. Animal models of age related macular degeneration.

    PubMed

    Pennesi, Mark E; Neuringer, Martha; Courtney, Robert J

    2012-08-01

    Age related macular degeneration (AMD) is the leading cause of vision loss of those over the age of 65 in the industrialized world. The prevalence and need to develop effective treatments for AMD has lead to the development of multiple animal models. AMD is a complex and heterogeneous disease that involves the interaction of both genetic and environmental factors with the unique anatomy of the human macula. Models in mice, rats, rabbits, pigs and non-human primates have recreated many of the histological features of AMD and provided much insight into the underlying pathological mechanisms of this disease. In spite of the large number of models developed, no one model yet recapitulates all of the features of human AMD. However, these models have helped reveal the roles of chronic oxidative damage, inflammation and immune dysregulation, and lipid metabolism in the development of AMD. Models for induced choroidal neovascularization have served as the backbone for testing new therapies. This article will review the diversity of animal models that exist for AMD as well as their strengths and limitations.

  14. Animal models of age related macular degeneration

    PubMed Central

    Pennesi, Mark E.; Neuringer, Martha; Courtney, Robert J.

    2013-01-01

    Age related macular degeneration (AMD) is the leading cause of vision loss of those over the age of 65 in the industrialized world. The prevalence and need to develop effective treatments for AMD has lead to the development of multiple animal models. AMD is a complex and heterogeneous disease that involves the interaction of both genetic and environmental factors with the unique anatomy of the human macula. Models in mice, rats, rabbits, pigs and non-human primates have recreated many of the histological features of AMD and provided much insight into the underlying pathological mechanisms of this disease. In spite of the large number of models developed, no one model yet recapitulates all of the features of human AMD. However, these models have helped reveal the roles of chronic oxidative damage, inflammation and immune dysregulation, and lipid metabolism in the development of AMD. Models for induced choroidal neovascularization have served as the backbone for testing new therapies. This article will review the diversity of animal models that exist for AMD as well as their strengths and limitations. PMID:22705444

  15. An evaluation of sex-age-kill (SAK) model performance

    USGS Publications Warehouse

    Millspaugh, Joshua J.; Skalski, John R.; Townsend, Richard L.; Diefenbach, Duane R.; Boyce, Mark S.; Hansen, Lonnie P.; Kammermeyer, Kent

    2009-01-01

    The sex-age-kill (SAK) model is widely used to estimate abundance of harvested large mammals, including white-tailed deer (Odocoileus virginianus). Despite a long history of use, few formal evaluations of SAK performance exist. We investigated how violations of the stable age distribution and stationary population assumption, changes to male or female harvest, stochastic effects (i.e., random fluctuations in recruitment and survival), and sampling efforts influenced SAK estimation. When the simulated population had a stable age distribution and λ > 1, the SAK model underestimated abundance. Conversely, when λ < 1, the SAK overestimated abundance. When changes to male harvest were introduced, SAK estimates were opposite the true population trend. In contrast, SAK estimates were robust to changes in female harvest rates. Stochastic effects caused SAK estimates to fluctuate about their equilibrium abundance, but the effect dampened as the size of the surveyed population increased. When we considered both stochastic effects and sampling error at a deer management unit scale the resultant abundance estimates were within ±121.9% of the true population level 95% of the time. These combined results demonstrate extreme sensitivity to model violations and scale of analysis. Without changes to model formulation, the SAK model will be biased when λ ≠ 1. Furthermore, any factor that alters the male harvest rate, such as changes to regulations or changes in hunter attitudes, will bias population estimates. Sex-age-kill estimates may be precise at large spatial scales, such as the state level, but less so at the individual management unit level. Alternative models, such as statistical age-at-harvest models, which require similar data types, might allow for more robust, broad-scale demographic assessments.

  16. The Implications of Detrital Zircon Maximum Depositional Age (MDA) from Large Sample Datasets (n>500)

    NASA Astrophysics Data System (ADS)

    Coutts, D. S.; Matthews, W.; Guest, B.; Hubbard, S. M.

    2015-12-01

    The youngest sub-population of a detrital zircon geochronological dataset is routinely used to approximate the age of deposition for a sample. The ages represent a maximum depositional age (MDA) because the detrital zircons analyzed crystallized at depth, in a magma chamber prior to being exposed at the surface through erosion or volcanic eruption. Dickinson and Gehrels (2009) demonstrate four methods of calculating the MDA of a zircon population using U-Pb ages, which are assessed in this study. Previous MDA studies used relatively small datasets (n<100), reducing the likelihood of finding the youngest population in a sample. We consider large-n datasets (n>500), which have a greater likelihood of capturing a significant proportion of the youngest population and therefore have the potential to improve the accuracy of a calculated MDA. We assess the effects of sample size and MDA calculation methods using a numerical model consisting of a simulated population of detrital zircon grains with known ages. Using our population of 25048 simulated grains, we ran repeated trials of varying sample sizes (n=50, 100, 300, 500, 700, 1000, 1500) to compare the output of MDA calculation techniques. As sample size increases the youngest sub-population of zircons is better defined, and the MDA decreases and becomes more precise. As a further test, model results are compared to U-Pb data (n=695) from a sample of the Maasrichtian-Paleocene Gabriola Formation (Nanaimo Group, B.C., Canada). Similar trials of varying sample sizes show the same decrease in MDA. Biostratigraphic analysis assigned the formation to the Maastrichtian (72.1 - 66.0 Ma), however, our results indicate that deposition took place in the Danian (66.0 - 61.6 Ma). This result has implications for the timing of forearc basin fill, and more broadly, the evolution of the Western North American Cordillera. MDA methods on large-n datasets can be used to hone stratigraphic correlations and calculate sediment accumulation

  17. Using Inverse Probability Bootstrap Sampling to Eliminate Sample Induced Bias in Model Based Analysis of Unequal Probability Samples.

    PubMed

    Nahorniak, Matthew; Larsen, David P; Volk, Carol; Jordan, Chris E

    2015-01-01

    In ecology, as in other research fields, efficient sampling for population estimation often drives sample designs toward unequal probability sampling, such as in stratified sampling. Design based statistical analysis tools are appropriate for seamless integration of sample design into the statistical analysis. However, it is also common and necessary, after a sampling design has been implemented, to use datasets to address questions that, in many cases, were not considered during the sampling design phase. Questions may arise requiring the use of model based statistical tools such as multiple regression, quantile regression, or regression tree analysis. However, such model based tools may require, for ensuring unbiased estimation, data from simple random samples, which can be problematic when analyzing data from unequal probability designs. Despite numerous method specific tools available to properly account for sampling design, too often in the analysis of ecological data, sample design is ignored and consequences are not properly considered. We demonstrate here that violation of this assumption can lead to biased parameter estimates in ecological research. In addition, to the set of tools available for researchers to properly account for sampling design in model based analysis, we introduce inverse probability bootstrapping (IPB). Inverse probability bootstrapping is an easily implemented method for obtaining equal probability re-samples from a probability sample, from which unbiased model based estimates can be made. We demonstrate the potential for bias in model-based analyses that ignore sample inclusion probabilities, and the effectiveness of IPB sampling in eliminating this bias, using both simulated and actual ecological data. For illustration, we considered three model based analysis tools--linear regression, quantile regression, and boosted regression tree analysis. In all models, using both simulated and actual ecological data, we found inferences to be

  18. Using Inverse Probability Bootstrap Sampling to Eliminate Sample Induced Bias in Model Based Analysis of Unequal Probability Samples

    PubMed Central

    Nahorniak, Matthew

    2015-01-01

    In ecology, as in other research fields, efficient sampling for population estimation often drives sample designs toward unequal probability sampling, such as in stratified sampling. Design based statistical analysis tools are appropriate for seamless integration of sample design into the statistical analysis. However, it is also common and necessary, after a sampling design has been implemented, to use datasets to address questions that, in many cases, were not considered during the sampling design phase. Questions may arise requiring the use of model based statistical tools such as multiple regression, quantile regression, or regression tree analysis. However, such model based tools may require, for ensuring unbiased estimation, data from simple random samples, which can be problematic when analyzing data from unequal probability designs. Despite numerous method specific tools available to properly account for sampling design, too often in the analysis of ecological data, sample design is ignored and consequences are not properly considered. We demonstrate here that violation of this assumption can lead to biased parameter estimates in ecological research. In addition, to the set of tools available for researchers to properly account for sampling design in model based analysis, we introduce inverse probability bootstrapping (IPB). Inverse probability bootstrapping is an easily implemented method for obtaining equal probability re-samples from a probability sample, from which unbiased model based estimates can be made. We demonstrate the potential for bias in model-based analyses that ignore sample inclusion probabilities, and the effectiveness of IPB sampling in eliminating this bias, using both simulated and actual ecological data. For illustration, we considered three model based analysis tools—linear regression, quantile regression, and boosted regression tree analysis. In all models, using both simulated and actual ecological data, we found inferences to be

  19. Computational modeling of material aging effects

    SciTech Connect

    Fang, H.E.

    1996-07-01

    Progress is being made in our efforts to develop computational models for predicting material property changes in weapon components due to aging. The first version of a two-dimensional lattice code for modeling thermomechanical fatigue, such as has been observed in solder joints on electronic components removed from the stockpile, has been written and tested. The code does a good qualitative job of presenting intergranular and/or transgranular cracking in a polycrystalline material when under thermomechanical deformation. The current progress is an encouraging start for our long term effort to develop multi-level simulation capabilities, with the technology of high performance computing, for predicting age-related effects on the reliability of weapons.

  20. Age of the moon: An isotopic study of uranium-thorium-lead systematics of lunar samples

    USGS Publications Warehouse

    Tatsumoto, M.; Rosholt, J.N.

    1970-01-01

    Concentrations of U, Th, and Pb in Apollo 11 samples studied are low (U. 0.16 to 0.87; Th, 0.53 to 3.4; Pb, 0.29 to 1.7, in ppm) but the extremely radiogenic lead in samples allows radiometric dating. The fine dust and the breccia have a concordant age of 4.66 billion years on the basis of 207Pb/206Pb, 206Pb/238U, 207Pb/235U, and 208Pb/232Th ratios. This age is comparable with the age of meteorites and with the age generally accepted for the earth. Six crystalline and vesicular samples are distinctly younger than the dust and breccia. The 238U/235U ratio is the same as that in earth rocks, and 234U is in radioactive equilibrium with parent 238U.

  1. Age of the moon: an isotopic study of uranium-thorium-lead systematics of lunar samples.

    PubMed

    Tatsumoto, M; Rosholt, J N

    1970-01-30

    Concentrations of U, Th, and Pb in Apollo 11 samples studied are low (U. 0.16 to 0.87; Th, 0.53 to 3.4; Pb, 0.29 to 1.7, in ppm) but the extremely radiogenic lead in samples allows radiometric dating. The fine dust and the breccia have a concordant age of 4.66 billion years on the basis of (207)Pb/(206)Pb, (206)Pb/(238)U, (207)Pb/(235U), and(208)Pb/(232)Th ratios. This age is comparable with the age of meteorites and with the age generally accepted for the earth. Six crystalline and vesicular samples are distinctly younger than the dust and breccia. The (238)U/(235)U ratio is the same as that in earth rocks, and (234)U is in radioactive equilibrium with parent (238)U.

  2. Aging, Breast Cancer and the Mouse Model

    DTIC Science & Technology

    2005-05-01

    Presenescent or senescent hBF (1.2 or 18x×10 4/well, respectively) [M, Stampfer , P. Yaswen, Lawrence Berkeley National Laboratory wdre suspended in 60 l cold...2.8 1 2.8 Inducing a human-like senescent phenotype in mouse fibroblasts Jean-Philihoo Copp , Simona Parrinello, Ana Krtolica, Christopher K. Patil...MAMMARY EPITHELIAL CELL PROLIFERATION AND TUMORIGENESIS: A MOUSE MODEL FOR HUMAN AGING. Jean-Philippe Coppe, Simona Parrinello, Ana Krtolica, Christopher

  3. Micromechanical Modeling of Concrete at Early Age

    NASA Astrophysics Data System (ADS)

    Tuleubekov, Kairat

    The focus of this research is a micromechanical characterization of Portland cement concrete at early age (less than 28 days). Concrete's viscoelastic properties change significantly at early age due to solidification of its matrix component. Bazant's solidification theory models concrete as a material solidifying in time. This approach is generalized to a three-dimensional characterization of a composite material with a solidifying matrix and elastic inclusions. An integral constitutive relationship was obtained using a generalized correspondence principle and homogenization techniques for elastic composite materials. In light of this approach, effective creep properties of composite spherical assemblage with an aging matrix are obtained. In addition, the elastic Hashin-Monteiro model is generalized to account for the effect of the interfacial transition zone properties on concrete creep. An effective computational platform was developed to evaluate operator expressions in order to obtain relaxation and creep functions numerically. Through numerical examples, it is shown that triaxial generalization of Bazant's solidification model enables robust and computationally efficient prediction of creep deformations in Portland cement concrete.

  4. Age Dependent Absolute Plate and Plume Motion Modeling

    NASA Astrophysics Data System (ADS)

    Heaton, D. E.; Koppers, A. A. P.

    2015-12-01

    Current absolute plate motion (APM) models from 80 - 0 Ma are constrained by the location of mantle plume related hotspot seamounts, in particular those of the Hawaiian-Emperor and Louisville seamount trails. Originally the 'fixed' hotspot hypothesis was developed to explain past plate motion based on linear age progressive intra-plate volcanism. However, now that 'moving' hotspots are accepted, it is becoming clear that APM models need to be corrected for individual plume motion vectors. For older seamount trails that were active between roughly 50 and 80 Ma the APM models that use 'fixed' hotspots overestimate the measured age progression in those trails, while APM models corrected for 'moving' hotspots underestimate those age progressions. These mismatches are due to both a lack of reliable ages in the older portions of both the Hawaii and Louisville seamount trails and insufficient APM modeling constraints from other seamount trails in the Pacific Basin. Seamounts are difficult to sample and analyze because many are hydrothermally altered and have low potassium concentrations. New 40Ar/39Ar Age results from International Ocean Drilling Project (IODP) Expedition 330 Sites U1372 (n=18), U1375 (n=3), U1376 (n=15) and U1377 (n=7) aid in constraining the oldest end of the Louisville Seamount trail. A significant observation in this study is that the age range recovered in the drill cores match the range of ages that were acquired on dredging cruises at the same seamounts (e.g. Koppers et al., 2011). This is important for determining the inception age of a seamount. The sections recovered from IODP EXP 330 are in-situ volcanoclastic breccia and lava flows. Comparing the seismic interpretations of Louisville guyots (Contreras-Reyes et al., 2010), Holes U1372, U1373 and U1374 penetrated the extrusive and volcanoclastic sections of the seamount. The ages obtained are consistent over stratigraphic intervals >100-450 m thick, providing evidence that these seamounts

  5. 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.

  6. Trajectories of Delinquency from Age 14 to 23 in the National Longitudinal Survey of Youth Sample

    PubMed Central

    Murphy, Debra A.; Brecht, Mary-Lynn; Huang, David; Herbeck, Diane M.

    2012-01-01

    This study utilized data from the National Longitudinal Survey of Youth to investigate risk trajectories for delinquency and factors associated with different trajectories, particularly substance use. The sample (N = 8,984) was 49% female. A group-based trajectory model was applied, which identified four distinct trajectories for both males and females: (1) a High group with delinquency rates consistently higher than other groups, with some decrease across the age range; (2) a Decreased group, beginning at high levels with substantial decrease to near zero; (3) a Moderate group experiencing some decline but remaining at moderate rates of delinquency through most of the age range; and (4) a consistently Low group, having low rates of delinquency declining to near zero by mid- to late-teens. The Low group was distinguished by several protective factors, including higher rates of maternal authoritative parenting style, possible lower acculturation (higher rates of non-English spoken at home), higher rates of religious activity, later substance use initiation, lower rates of early delinquent activity, less early experience with neighborhood or personal violence, and higher rates of perceiving penalty for wrongdoing. Conversely, the High group was characterized by several vulnerability factors—essentially the converse of the protective factors above. PMID:23105164

  7. Isotopic composition analysis and age dating of uranium samples by high resolution gamma ray spectrometry

    NASA Astrophysics Data System (ADS)

    Apostol, A. I.; Pantelica, A.; Sima, O.; Fugaru, V.

    2016-09-01

    Non-destructive methods were applied to determine the isotopic composition and the time elapsed since last chemical purification of nine uranium samples. The applied methods are based on measuring gamma and X radiations of uranium samples by high resolution low energy gamma spectrometric system with planar high purity germanium detector and low background gamma spectrometric system with coaxial high purity germanium detector. The ;Multigroup γ-ray Analysis Method for Uranium; (MGAU) code was used for the precise determination of samples' isotopic composition. The age of the samples was determined from the isotopic ratio 214Bi/234U. This ratio was calculated from the analyzed spectra of each uranium sample, using relative detection efficiency. Special attention is paid to the coincidence summing corrections that have to be taken into account when performing this type of analysis. In addition, an alternative approach for the age determination using full energy peak efficiencies obtained by Monte Carlo simulations with the GESPECOR code is described.

  8. Category fluency in a latino sample: associations with age, education, gender, and language.

    PubMed

    Mack, Wendy J; Teng, Evelyn; Zheng, Ling; Paz, Sylvia; Chui, Helena; Varma, Rohit

    2005-07-01

    The authors know of no published studies that have evaluated the effect of Spanish- versus English-language on category fluency within a sample of United States Latinos only. As part of a pilot study for the institution of a cognitive screening program in a cohort of Latinos, we assessed category fluency (fruits, vegetables, and "other" supermarket items) in a sample of 90 self-identified Latino community residents (aged 52-84, 0-18 years of education). The primary demographic correlates of category fluency were age and education. The decrement in naming of fruits with age was limited to the older old subjects (>age 70). Relatively younger old subjects (aged 61-70) did not differ from middle-aged subjects on category fluency. Gender showed little relationship to category naming. Persons naming in Spanish named significantly fewer 'other supermarket' items, but did not differ from English speakers in the more common fluency categories of fruits and vegetables. This analysis of category fluency in an ethnically homogenous sample with a wide range of formal education provided an evaluation of the effects of chosen language free of possible confounding by cultural differences, and also provided a more complete evaluation of the influence of education on category fluency.

  9. Multifractality, sample entropy, and wavelet analyses for age-related changes in the peripheral cardiovascular system: preliminary results.

    PubMed

    Humeau, Anne; Chapeau-Blondeau, François; Rousseau, David; Rousseau, Pascal; Trzepizur, Wojciech; Abraham, Pierre

    2008-02-01

    Using signal processing measures we evaluate the effect of aging on the peripheral cardiovascular system. Laser Doppler flowmetry (LDF) signals, reflecting the microvascular perfusion, are recorded on the forearm of 27 healthy subjects between 20-30, 40-50, or 60-70 years old. Wavelet-based representations, Hölder exponents, and sample entropy values are computed for each time series. The results indicate a possible modification of the peripheral cardiovascular system with aging. Thus, the endothelial-related metabolic activity decreases, but not significantly, with aging. Furthermore, LDF signals are more monofractal for elderly subjects than for young people for whom LDF signals are weakly multifractal: the average range of Holder exponents computed with a parametric generalized quadratic variation based estimation method is 0.13 for subjects between 20 and 30 years old and 0.06 for subjects between 60 and 70 years old. Moreover, the average mean sample entropy value of LDF signals slightly decreases with age: it is 1.34 for subjects between 20 and 30 years old and 1.19 for subjects between 60 and 70 years old. Our results could assist in gaining knowledge on the relationship between microvascular system status and age and could also lead to a more accurate age-related nonlinear modeling.

  10. Creating Composite Age Groups to Smooth Percentile Rank Distributions of Small Samples

    ERIC Educational Resources Information Center

    Lopez, Francesca; Olson, Amy; Bansal, Naveen

    2011-01-01

    Individually administered tests are often normed on small samples, a process that may result in irregularities within and across various age or grade distributions. Test users often smooth distributions guided by Thurstone assumptions (normality and linearity) to result in norms that adhere to assumptions made about how the data should look. Test…

  11. Towards an Analytical Age-Dependent Model of Contrast Sensitivity Functions for an Ageing Society

    PubMed Central

    Joulan, Karine; Brémond, Roland

    2015-01-01

    The Contrast Sensitivity Function (CSF) describes how the visibility of a grating depends on the stimulus spatial frequency. Many published CSF data have demonstrated that contrast sensitivity declines with age. However, an age-dependent analytical model of the CSF is not available to date. In this paper, we propose such an analytical CSF model based on visual mechanisms, taking into account the age factor. To this end, we have extended an existing model from Barten (1999), taking into account the dependencies of this model's optical and physiological parameters on age. Age-dependent models of the cones and ganglion cells densities, the optical and neural MTF, and optical and neural noise are proposed, based on published data. The proposed age-dependent CSF is finally tested against available experimental data, with fair results. Such an age-dependent model may be beneficial when designing real-time age-dependent image coding and display applications. PMID:26078994

  12. Creating Better School-Age Care Jobs: Model Work Standards.

    ERIC Educational Resources Information Center

    Haack, Peggy

    Built on the premise that good school-age care jobs are the cornerstone of high-quality services for school-age youth and their families, this guide presents model work standards for school-age care providers. The guide begins with a description of the strengths and challenges of the school-age care profession. The model work standards are…

  13. Testing the applicability of six macroscopic skeletal aging techniques on a modern Southeast Asian sample.

    PubMed

    Gocha, Timothy P; Ingvoldstad, Megan E; Kolatorowicz, Adam; Cosgriff-Hernandez, Meghan-Tomasita J; Sciulli, Paul W

    2015-04-01

    Most macroscopic skeletal aging techniques used by forensic anthropologists have been developed and tested only on reference material from western populations. This study examined the performance of six aging techniques on a known age sample of 88 Southeast Asian individuals. Methods examined included the Suchey-Brooks method of aging the symphyseal face of the os pubis (Brooks and Suchey, Hum. Evol. 5 (1990) 227), Buckberry and Chamberlain's, Am. J. Phys. Anthropol. 119 (2002) 231 and Osborne et al.'s, J. Forensic Sci. 49 (2004) 1 revisions of the Lovejoy et al., Am. J. Phys. Anthropol. 68 (1985) 15 method of aging the auricular surface of the ilium, İşcan et al.'s, J. Forensic Sci. 29 (1984) 1094, İşcan et al.'s, J. Forensic Sci. 30 (1985) 853 method of aging the sternal end of the fourth rib, and Meindl and Lovejoy's, Am. J. Phys. Anthropol. 68 (1985) 57 methods for aging both lateral-anterior and vault sutures on the cranium. The results of this study indicate that application of aging techniques commonly used in forensic anthropology to individuals identified as Asian, and more specifically Southeast Asian, should not be undertaken injudiciously. Of the six individual methods tested here, the Suchey-Brooks pubic symphysis aging method performs best, though average age estimates were still off by nearly 10 years or greater. Methods for aging the auricular surface perform next best, though the Osborne et al. method works better for individuals below 50 years and the Buckberry and Chamberlain method works better for those above 50 years. Methods for age estimation from the sternal ends of the fourth rib and vault and lateral-anterior cranial sutures perform poorly and are not recommended for use on remains of Southeast Asian ancestry. Combining age estimates from multiple indicators, specifically the pubic symphysis and one auricular surface method, was superior to individual methods. Data and a worked example are provided for calculating the conditional

  14. Economic Hardship and Biological Weathering: The Epigenetics of Aging in a U.S. Sample of Black Women

    PubMed Central

    Lei, Man Kit; Beach, Steven R.H.; Philibert, Robert A.; Cutrona, Carolyn E.; Gibbons, Frederick X.; Barr, Ashley

    2016-01-01

    Background Past research has linked low socio-economic status (SES) to inflammation, metabolic dysregulation, and various chronic and age-related diseases such as type 2 diabetes, coronary heart disease, stroke, and dementia. These studies suggest that the challenges and adversities associated with low SES may result in premature aging and increased risk of morbidity and mortality. Objective Building upon this research, the present study investigates additional avenues whereby low income might accelerate biological aging. Methods Structural equation modeling and longitudinal data from a sample of 100 Black, middle-aged women residing in the United States was used to investigate the effect of income on a recently developed epigenetic measure of biological aging. This measure can be used as a “biological clock” to assess, at any point during adulthood, the extent to which an individual is experiencing accelerated or decelerated biological aging. Results Low income displayed a robust association with accelerated aging that was unaffected after controlling for other SES-related factors such as education, marital status, and childhood adversity. Further, our analyses indicated that the association between income and biological aging was not explained by health-related behaviors such as diet, exercise, smoking, alcohol consumption, or having health insurance. Rather, in large measure, it was financial pressure (difficulty paying bills, buying necessities, or meeting daily expenses) that accounted for the association between low income and accelerated aging. Conclusions These findings support the view that chronic financial pressures associated with low income exerts a weathering effect that results in premature aging. PMID:26765221

  15. Development of a bioenergetics model for age-0 American Shad

    USGS Publications Warehouse

    Sauter, Sally T.

    2011-01-01

    many of the salmonids and predatory fishes encountered in the lower Columbia River (Petersen and Ward 1999). The Wisconsin bioenergetics model has not been developed for American shad, however Limburg (1996) parameterized a simplified bioenergetics growth model for this species. A common application for the Wisconsin bioenergetics model is to estimate the consumption or growth of a fish population under different temperature and feeding scenarios (Ney 1993). One advantage of the bioenergetics approach is that consumption can be estimated without direct field measurements of predation rate (prey·predator-1· day-1; Petersen and Ward 1999). Field estimates of fish consumption are time consuming and costly to determine, and estimates may show wide variance due to environmental and sampling variability. However, the consumption parameters used in a newly developed bioenergetics model must be verified with field and laboratory estimates of consumption (Ney 1993).


    The objective of this research was to parameterize a Wisconsin bioenergetics model for age-0 American shad using published physiological data on American shad and closely related alosine species. The American shad bioenergetics model will be used as a tool to explore various hypotheses about how age-0 American shad directly and indirectly affect Columbia River salmon through ecological interactions in lower Columbia River food webs. One over-arching focus of the larger research project was to identify potential interactions between age-0 American shad and juvenile salmonids, addressing potential outcomes through bioenergetics modeling scenarios. This report contains two bioenergetics modeling applications to demonstrate how these models can be used to address management questions and direct research effort. The first modeling application uses the American shad bioenergetics model described in this report to explore prey consumption by age-0 American shad (Chapter 1, this report

  16. Speciation Effect in the Penna Aging Model

    NASA Astrophysics Data System (ADS)

    Łaszkiewicz, A.; Szymczak, Sz.; Cebrat, S.

    We have simulated the evolution of diploid, sexually reproducing populations using the Penna model of aging. We have noted that diminishing the recombination frequency during the gamete production generates a specific diversity of genomes in the populations. When two populations independently evolving for some time were mixed in one environmental niche of the limited size and crossbreeding between them was allowed, the average lifespan of hybrids was significantly shorter than the lifespan of the individuals of parental lines. Another effect of higher hybrid mortality is the faster elimination of one parental line from the shared environment. The two populations living in one environment co-exist much longer if they are genetically separated — they compete as two species instead of crossbreeding. This effect can be considered as the first step to speciation — any barrier eliminating crossbreeding between these populations, leading to speciation, would favor the populations.

  17. Virginia Opossums, Minimum Reproduction Age and Predators in the Penna Aging Model

    NASA Astrophysics Data System (ADS)

    Altevolmer, A. K.

    Age-specific predators are introduced into the Penna model of biological aging. It is shown that populations with a variable minimum reproduction age find a stable state with an earlier onset of reproduction, if older ages are eaten by the predators. This behavior agrees with the demographic data of the Virgina opossum.

  18. The Use of Dried Blood Spot Sampling in the National Social Life, Health, and Aging Project

    PubMed Central

    McDade, Thomas W.

    2009-01-01

    Objectives This paper describes the methods used for and issues associated with collection and analysis of dried blood spot (DBS) samples for the National Social Life, Health, and Aging Project and provides the basic distributions of the resulting analytes. Methods DBSs from capillary finger sticks were collected by nonmedically trained interviewers from 2,044 individuals, aged 57–85 years. The quality and quantity of DBS samples were evaluated to allow for analysis of interviewer performance. Levels of C-reactive protein, antibodies to the Epstein–Barr virus, hemoglobin, and glycosylated hemoglobin were assayed using various analytic methods. Results Cooperation rate for DBS collection was 84.5%, with 99% of the cards yielding enough sample for at least one analysis. The distribution, mean, and standard deviation of the analytes obtained from DBSs are also presented in this paper. Conclusions The high cooperation rate and quality of the spots collected suggest that the collection of DBSs in population-based research is a feasible and viable alternative to venous blood draws. The relative ease of sample collection, transport, and storage are significant benefits. Care should be taken, however, when comparing results from analysis of DBS samples with those obtained from serum or plasma samples. PMID:19244547

  19. Conceptualizing age-friendly community characteristics in a sample of urban elders: an exploratory factor analysis.

    PubMed

    Smith, Richard J; Lehning, Amanda J; Dunkle, Ruth E

    2013-01-01

    Accurate conceptualization and measurement of age-friendly community characteristics would help to reduce barriers to documenting the effects on elders of interventions to create such communities. This article contributes to the measurement of age-friendly communities through an exploratory factor analysis of items reflecting an existing US Environmental Protection Agency policy framework. From a sample of urban elders (n = 1,376), we identified 6 factors associated with demographic and health characteristics: access to business and leisure, social interaction, access to health care, neighborhood problems, social support, and community engagement. Future research should explore the effects of these factors across contexts and populations.

  20. Frequency sampling in microhistological studies: An alternative model

    USGS Publications Warehouse

    Williams, B.K.

    1987-01-01

    Frequency sampling in microhistological studies is discussed in terms of sampling procedures, statistical properties, and biological inferences. Two sampling approaches are described and con-trasted, and some standard methods for improving the stability of density estimators are discussed. Possible sources of difficulty are highlighted in terms of sampling design and statistical analysis. An alternative model is proposed that accounts for 2-stage sampling, and yields reasonable, we!!-behaved estimates of relative densities.

  1. Personality and Other Lifelong Influences on Older-Age Health and Wellbeing: Preliminary Findings in Two Scottish Samples.

    PubMed

    Harris, Mathew A; Brett, Caroline E; Starr, John M; Deary, Ian J; Johnson, Wendy

    2016-01-01

    Recent observations that personality traits are related to later-life health and wellbeing have inspired considerable interest in exploring the mechanisms involved. Other factors, such as cognitive ability and education, also show longitudinal influences on health and wellbeing, but it is not yet clear how all these early-life factors together contribute to later-life health and wellbeing. In this preliminary study, we assessed hypothesised relations among these variables across the life course, using structural equation modelling in a sample assessed on dependability (a personality trait related to conscientiousness) in childhood, cognitive ability and social class in childhood and older age, education, and health and subjective wellbeing in older age. Our models indicated that both health and subjective wellbeing in older age were influenced by childhood IQ and social class, via education. Some older-age personality traits mediated the effects of early-life variables, on subjective wellbeing in particular, but childhood dependability did not show significant associations. Our results therefore did not provide evidence that childhood dependability promotes older-age health and wellbeing, but did highlight the importance of other early-life factors, particularly characteristics that contribute to educational attainment. Further, personality in later life may mediate the effects of early-life factors on health and subjective wellbeing. © 2016 The Authors. European Journal of Personality published by John Wiley & Sons Ltd on behalf of European Association of Personality Psychology.

  2. Personality and Other Lifelong Influences on Older‐Age Health and Wellbeing: Preliminary Findings in Two Scottish Samples

    PubMed Central

    Brett, Caroline E.; Starr, John M.; Deary, Ian J.

    2016-01-01

    Abstract Recent observations that personality traits are related to later‐life health and wellbeing have inspired considerable interest in exploring the mechanisms involved. Other factors, such as cognitive ability and education, also show longitudinal influences on health and wellbeing, but it is not yet clear how all these early‐life factors together contribute to later‐life health and wellbeing. In this preliminary study, we assessed hypothesised relations among these variables across the life course, using structural equation modelling in a sample assessed on dependability (a personality trait related to conscientiousness) in childhood, cognitive ability and social class in childhood and older age, education, and health and subjective wellbeing in older age. Our models indicated that both health and subjective wellbeing in older age were influenced by childhood IQ and social class, via education. Some older‐age personality traits mediated the effects of early‐life variables, on subjective wellbeing in particular, but childhood dependability did not show significant associations. Our results therefore did not provide evidence that childhood dependability promotes older‐age health and wellbeing, but did highlight the importance of other early‐life factors, particularly characteristics that contribute to educational attainment. Further, personality in later life may mediate the effects of early‐life factors on health and subjective wellbeing. © 2016 The Authors. European Journal of Personality published by John Wiley & Sons Ltd on behalf of European Association of Personality Psychology PMID:27867259

  3. Validating the Student-Teacher Relationship Scale: testing factor structure and measurement invariance across child gender and age in a Dutch sample.

    PubMed

    Koomen, Helma M Y; Verschueren, Karine; van Schooten, Erik; Jak, Suzanne; Pianta, Robert C

    2012-04-01

    The Student-Teacher Relationship Scale (STRS) is widely used to examine teachers' relationships with young students in terms of closeness, conflict, and dependency. This study aimed to verify the dimensional structure of the STRS with confirmatory factor analysis, test its measurement invariance across child gender and age, improve its measurement of the dependency construct, and extend its age range. Teachers completed a slightly adapted STRS for a Dutch sample of 2335 children aged 3 to 12. Overall, the 3-factor model showed an acceptable fit. Results indicated metric invariance across gender and age up to 8years. Scalar invariance generally did not hold. Lack of metric invariance at ages 8 to 12 primarily involved Conflict items, whereas scale differences across gender and age primarily involved Closeness items. The adapted Dependency scale showed strong invariance and higher internal consistencies than the original scale for this Dutch sample. Importantly, the revealed non-invariance for gender and age did not influence mean group comparisons.

  4. Emotional Experience Improves With Age: Evidence Based on Over 10 Years of Experience Sampling

    PubMed Central

    Carstensen, Laura L.; Turan, Bulent; Scheibe, Susanne; Ram, Nilam; Ersner-Hershfield, Hal; Samanez-Larkin, Gregory R.; Brooks, Kathryn P.; Nesselroade, John R.

    2012-01-01

    Recent evidence suggests that emotional well-being improves from early adulthood to old age. This study used experience-sampling to examine the developmental course of emotional experience in a representative sample of adults spanning early to very late adulthood. Participants (N = 184, Wave 1; N = 191, Wave 2; N = 178, Wave 3) reported their emotional states at five randomly selected times each day for a one week period. Using a measurement burst design, the one-week sampling procedure was repeated five and then ten years later. Cross-sectional and growth curve analyses indicate that aging is associated with more positive overall emotional well-being, with greater emotional stability and with more complexity (as evidenced by greater co-occurrence of positive and negative emotions). These findings remained robust after accounting for other variables that may be related to emotional experience (personality, verbal fluency, physical health, and demographic variables). Finally, emotional experience predicted mortality; controlling for age, sex, and ethnicity, individuals who experienced relatively more positive than negative emotions in everyday life were more likely to have survived over a 13 year period. Findings are discussed in the theoretical context of socioemotional selectivity theory. PMID:20973600

  5. Age and compositional data of zircon from sepiolite drilling mud to identify contamination of ocean drilling samples

    NASA Astrophysics Data System (ADS)

    Andrews, Graham D. M.; Schmitt, Axel K.; Busby, Cathy J.; Brown, Sarah R.; Blum, Peter; Harvey, Janet. C.

    2016-08-01

    Zircon extracted from drilled oceanic rocks is increasingly used to answer geologic questions related to igneous and sedimentary sequences. Recent zircon studies using samples obtained from marine drill cores revealed that drilling muds used in the coring process may contaminate the samples. The JOIDES Resolution Science Operator of the International Ocean Discovery Program has been using two types of clays, sepiolite and attapulgite, which both have salt water viscosifier properties able to create a gel-like slurry that carries drill cuttings out of the holes several hundred meters deep. The dominantly used drilling mud is sepiolite originating from southwestern Nevada, USA. This sepiolite contains abundant zircon crystals with U-Pb ages ranging from 1.89 to 2889 Ma and continental trace element, δ18O, and ɛHf isotopic compositions. A dominant population of 11-16 Ma zircons in sepiolite drilling mud makes identification of contamination in drilled Neogene successions particularly challenging. Interpretation of zircon analyses related to ocean drilling should be cautious of zircon ages in violation of independently constrained age models and that have age populations overlapping those in the sepiolite. Because individual geochronologic and geochemical characteristics lack absolute discriminatory power, it is recommended to comprehensively analyze all dated zircon crystals from cores exposed to drill mud for trace element, δ18O, and ɛHf isotopic compositions. Zircon analyzed in situ (i.e., in petrographic sections) are assumed to be trustworthy.

  6. Evolutionary model with genetics, aging, and knowledge

    NASA Astrophysics Data System (ADS)

    Bustillos, Armando Ticona; de Oliveira, Paulo Murilo

    2004-02-01

    We represent a process of learning by using bit strings, where 1 bits represent the knowledge acquired by individuals. Two ways of learning are considered: individual learning by trial and error, and social learning by copying knowledge from other individuals or from parents in the case of species with parental care. The age-structured bit string allows us to study how knowledge is accumulated during life and its influence over the genetic pool of a population after many generations. We use the Penna model to represent the genetic inheritance of each individual. In order to study how the accumulated knowledge influences the survival process, we include it to help individuals to avoid the various death situations. Modifications in the Verhulst factor do not show any special feature due to its random nature. However, by adding years to life as a function of the accumulated knowledge, we observe an improvement of the survival rates while the genetic fitness of the population becomes worse. In this latter case, knowledge becomes more important in the last years of life where individuals are threatened by diseases. Effects of offspring overprotection and differences between individual and social learning can also be observed. Sexual selection as a function of knowledge shows some effects when fidelity is imposed.

  7. Radiocarbon ages and age models for the past 30,000 years in Bear Lake, Utah and Idaho

    USGS Publications Warehouse

    Colman, Steven M.; Rosenbaum, J.G.; Kaufman, D.S.; Dean, W.E.; McGeehin, J.P.

    2009-01-01

    Radiocarbon analyses of pollen, ostracodes, and total organic carbon (TOC) provide a reliable chronology for the sediments deposited in Bear Lake over the past 30,000 years. The differences in apparent age between TOC, pollen, and carbonate fractions are consistent and in accord with the origins of these fractions. Comparisons among different fractions indicate that pollen sample ages are the most reliable, at least for the past 15,000 years. The post-glacial radiocarbon data also agree with ages independently estimated from aspartic acid racemization in ostracodes. Ages in the red, siliclastic unit, inferred to be of last glacial age, appear to be several thousand years too old, probably because of a high proportion of reworked, refractory organic carbon in the pollen samples. Age-depth models for five piston cores and the Bear Lake drill core (BL00-1) were constructed by using two methods: quadratic equations and smooth cubic-splinefits. The two types of age models differ only in detail for individual cores, and each approach has its own advantages. Specific lithological horizons were dated in several cores and correlated among them, producing robust average ages for these horizons. The age of the correlated horizons in the red, siliclastic unit can be estimated from the age model for BL00-1, which is controlled by ages above and below the red, siliclastic unit. These ages were then transferred to the correlative horizons in the shorter piston cores, providing control for the sections of the age models in those cores in the red, siliclastic unit. These age models are the backbone for reconstructions of past environmental conditions in Bear Lake. In general, sedimentation rates in Bear Lake have been quite uniform, mostly between 0.3 and 0.8 mm yr-1 in the Holocene, and close to 0.5 mm yr-1 for the longer sedimentary record in the drill core from the deepest part of the lake. Copyright ?? 2009 The Geological Society of America.

  8. Sample size matters: Investigating the optimal sample size for a logistic regression debris flow susceptibility model

    NASA Astrophysics Data System (ADS)

    Heckmann, Tobias; Gegg, Katharina; Becht, Michael

    2013-04-01

    Statistical approaches to landslide susceptibility modelling on the catchment and regional scale are used very frequently compared to heuristic and physically based approaches. In the present study, we deal with the problem of the optimal sample size for a logistic regression model. More specifically, a stepwise approach has been chosen in order to select those independent variables (from a number of derivatives of a digital elevation model and landcover data) that explain best the spatial distribution of debris flow initiation zones in two neighbouring central alpine catchments in Austria (used mutually for model calculation and validation). In order to minimise problems arising from spatial autocorrelation, we sample a single raster cell from each debris flow initiation zone within an inventory. In addition, as suggested by previous work using the "rare events logistic regression" approach, we take a sample of the remaining "non-event" raster cells. The recommendations given in the literature on the size of this sample appear to be motivated by practical considerations, e.g. the time and cost of acquiring data for non-event cases, which do not apply to the case of spatial data. In our study, we aim at finding empirically an "optimal" sample size in order to avoid two problems: First, a sample too large will violate the independent sample assumption as the independent variables are spatially autocorrelated; hence, a variogram analysis leads to a sample size threshold above which the average distance between sampled cells falls below the autocorrelation range of the independent variables. Second, if the sample is too small, repeated sampling will lead to very different results, i.e. the independent variables and hence the result of a single model calculation will be extremely dependent on the choice of non-event cells. Using a Monte-Carlo analysis with stepwise logistic regression, 1000 models are calculated for a wide range of sample sizes. For each sample size

  9. Preliminary Proactive Sample Size Determination for Confirmatory Factor Analysis Models

    ERIC Educational Resources Information Center

    Koran, Jennifer

    2016-01-01

    Proactive preliminary minimum sample size determination can be useful for the early planning stages of a latent variable modeling study to set a realistic scope, long before the model and population are finalized. This study examined existing methods and proposed a new method for proactive preliminary minimum sample size determination.

  10. Damages dependent sensitivity of Zircon (U-Th)/He ages to thermal processes: the case of Pyrenean samples

    NASA Astrophysics Data System (ADS)

    Pik, Raphael; Zimmermann, Laurent; Bellahsen, Nicolas; Vacherat, Arnaud; Ternois, Sébastien; Mouthereau, Frédéric; Ford, Mary

    2016-04-01

    Guenthner et al. 4, yet it is not possible to fit the data with a t-T history constrained by independent parameters (age of granites, old exhumation period followed by Cretaceous sediment burial). Even considering the maximum alpha-dose experienced by the samples (i.e. produced by the grains since granites emplaced without any annealing), the inversion of positive to negative trends in Bielsa and Neouvielle samples is centered at about 2 - 3 x 1017 alpha/g, significantly lower than the value used in the models 3,4. Preliminary Raman Spectroscopy data indicate that the total amount of damages experienced by these samples is well correlated with this double-trend pattern, and in the range of values used for quantification of the model with experimental diffusion data. These data from Pyrenean granites represent a good and independently constrained dataset to test the new complex models of age simulation and to optimize their calibration. They suggest in particular that the quantification, nature and preservation of damages acting for the modulation of He diffusion in zircons should be investigated and documented more extensively in the future.

  11. Stability of human α-salivary amylase in aged forensic samples.

    PubMed

    Carboni, Ilaria; Rapi, Stefano; Ricci, Ugo

    2014-07-01

    The unequivocal tissue identification in forensic casework samples is a key step for crime scene reconstruction. Just knowing the origin of a fluid can sometimes be enough to either prove or disprove a fact in court. Despite the importance of this test, very few data are available in literature concerning human saliva identification in old forensic caseworks. In this work the stability of human α-amylase activity in aged samples is described by using three different methods integrated with DNA profiling techniques. This analytical protocol was successfully applied on 26-years old samples coming from anonymous threat letters sent to prosecutors who were working on "the Monster of Florence", a case of serial murders happened around Florence (Italy) between 1968 and 1985.

  12. Preferential sampling and Bayesian geostatistics: Statistical modeling and examples.

    PubMed

    Cecconi, Lorenzo; Grisotto, Laura; Catelan, Dolores; Lagazio, Corrado; Berrocal, Veronica; Biggeri, Annibale

    2016-08-01

    Preferential sampling refers to any situation in which the spatial process and the sampling locations are not stochastically independent. In this paper, we present two examples of geostatistical analysis in which the usual assumption of stochastic independence between the point process and the measurement process is violated. To account for preferential sampling, we specify a flexible and general Bayesian geostatistical model that includes a shared spatial random component. We apply the proposed model to two different case studies that allow us to highlight three different modeling and inferential aspects of geostatistical modeling under preferential sampling: (1) continuous or finite spatial sampling frame; (2) underlying causal model and relevant covariates; and (3) inferential goals related to mean prediction surface or prediction uncertainty.

  13. An environmental sampling model for combining judgment and randomly placed samples

    SciTech Connect

    Sego, Landon H.; Anderson, Kevin K.; Matzke, Brett D.; Sieber, Karl; Shulman, Stanley; Bennett, James; Gillen, M.; Wilson, John E.; Pulsipher, Brent A.

    2007-08-23

    In the event of the release of a lethal agent (such as anthrax) inside a building, law enforcement and public health responders take samples to identify and characterize the contamination. Sample locations may be rapidly chosen based on available incident details and professional judgment. To achieve greater confidence of whether or not a room or zone was contaminated, or to certify that detectable contamination is not present after decontamination, we consider a Bayesian model for combining the information gained from both judgment and randomly placed samples. We investigate the sensitivity of the model to the parameter inputs and make recommendations for its practical use.

  14. Predictors of retest effects in a longitudinal study of cognitive aging in a diverse community-based sample

    PubMed Central

    Gross, Alden L.; Benitez, Andreana; Shih, Regina; Bangen, Katherine J.; Glymour, M Maria M; Sachs, Bonnie; Sisco, Shannon; Skinner, Jeannine; Schneider, Brooke C.; Manly, Jennifer J.

    2016-01-01

    OBJECTIVE Better performance due to repeated testing can bias long-term trajectories of cognitive aging and correlates of change. We examined whether retest effects differ as a function of individual differences pertinent to cognitive aging: race/ethnicity, age, sex, language, years of education, and dementia risk factors including APOE ε4 status, baseline cognitive performance, and cardiovascular risk. METHOD We used data from the Washington Heights-Inwood Columbia Aging Project, a community-based cohort of older adults (n=4,073). We modeled cognitive change and retest effects in summary factors for general cognitive performance, memory, executive functioning, and language using multilevel models. Retest effects were parameterized in two ways, as improvement between the first and subsequent testings, and as the square root of the number of prior testings. We evaluated whether the retest effect differed by individual characteristics. RESULTS The mean retest effect for general cognitive performance was 0.60 standard deviations (95%CI: 0.46, 0.74), and was similar for memory, executive functioning, and language. Retest effects were greater for participants in the lowest quartile of cognitive performance, consistent with regression to the mean. Retest did not differ by other characteristics. CONCLUSIONS Retest effects are large in this community-based sample, but do not vary by demographic or dementia-related characteristics. Differential retest effects may not limit the generalizability of inferences across different groups in longitudinal research. PMID:26527240

  15. Wang-Landau sampling with logarithmic windows for continuous models.

    PubMed

    Xie, Y L; Chu, P; Wang, Y L; Chen, J P; Yan, Z B; Liu, J-M

    2014-01-01

    We present a modified Wang-Landau sampling (MWLS) for continuous statistical models by partitioning the energy space into a set of windows with logarithmically shrinking width. To demonstrate its necessity and advantages, we apply this sampling to several continuous models, including the two-dimensional square XY spin model, triangular J1-J2 spin model, and Lennard-Jones cluster model. Given a finite number of bins for partitioning the energy space, the conventional Wang-Landau sampling may not generate sufficiently accurate density of states (DOS) around the energy boundaries. However, it is demonstrated that much more accurate DOS can be obtained by this MWLS, and thus a precise evaluation of the thermodynamic behaviors of the continuous models at extreme low temperature (kBT<0.1) becomes accessible. The present algorithm also allows efficient computation besides the highly reliable data sampling.

  16. Biological implications of the Weibull and Gompertz models of aging.

    PubMed

    Ricklefs, Robert E; Scheuerlein, Alex

    2002-02-01

    Gompertz and Weibull functions imply contrasting biological causes of demographic aging. The terms describing increasing mortality with age are multiplicative and additive, respectively, which could result from an increase in the vulnerability of individuals to extrinsic causes in the Gompertz model and the predominance of intrinsic causes at older ages in the Weibull model. Experiments that manipulate extrinsic mortality can distinguish these biological models. To facilitate analyses of experimental data, we defined a single index for the rate of aging (omega) for the Weibull and Gompertz functions. Each function described the increase in aging-related mortality in simulated ages at death reasonably well. However, in contrast to the Weibull omega(W), the Gompertz omega(G) was sensitive to variation in the initial mortality rate independently of aging-related mortality. Comparisons between wild and captive populations appear to support the intrinsic-causes model for birds, but give mixed support for both models in mammals.

  17. Modeling the Phenotypic Architecture of Autism Symptoms from Time of Diagnosis to Age 6

    ERIC Educational Resources Information Center

    Georgiades, Stelios; Boyle, Michael; Szatmari, Peter; Hanna, Steven; Duku, Eric; Zwaigenbaum, Lonnie; Bryson, Susan; Fombonne, Eric; Volden, Joanne; Mirenda, Pat; Smith, Isabel; Roberts, Wendy; Vaillancourt, Tracy; Waddell, Charlotte; Bennett, Teresa; Elsabbagh, Mayada; Thompson, Ann

    2014-01-01

    The latent class structure of autism symptoms from the time of diagnosis to age 6 years was examined in a sample of 280 children with autism spectrum disorder. Factor mixture modeling was performed on 26 algorithm items from the Autism Diagnostic Interview-Revised at diagnosis (Time 1) and again at age 6 (Time 2). At Time 1, a…

  18. A re-examination of cremains weight: sex and age variation in a Northern California sample.

    PubMed

    Van Deest, Traci L; Murad, Turhon A; Bartelink, Eric J

    2011-03-01

    The reduction of modern commercially cremated remains into a fine powder negates the use of traditional methods of skeletal analysis. The literature on the use of cremains weight for estimating aspects of the biologic profile is limited, often with conflicting results. This study re-evaluates the value of weight in the assessment of biologic parameters from modern cremated remains. A sample of adults was collected in northern California (n = 756), with a cremains weight averaging 2737.1 g. Males were significantly heavier than females (mean = 3233.2 g versus mean = 2238.3 g, respectively; p<0.001). Comparison of this sample with other previously reported samples from southern California, Florida, and Tennessee indicates a consistent sex difference, with the most similar mean values to the Tennessee study. Although cremains weight decreases with age as expected, the relationship is weak; thus, cremains weight cannot accurately predict age-at-death. While sex estimation shows considerable accuracy (86.3% for males and 80.9% for females), sectioning points may be population specific.

  19. DNA extraction from aged skeletal samples for STR typing by capillary electrophoresis.

    PubMed

    Huel, René; Amory, Sylvain; Bilić, Ana; Vidović, Stojko; Jasaragić, Edin; Parsons, Thomas J

    2012-01-01

    STR analysis of DNA extracted from skeletal samples can play an important role in the identification of missing persons. Here we present a method for the extraction of DNA from skeletal samples involving complete demineralization and digestion of the sample, followed by purification by silica binding. This method, together with the multiplex STR typing approach also presented, has proven highly successful in the recovery of DNA profiles from degraded, aged skeletal remains from a wide range of environmental contexts. The methodological steps presented include bone decontamination and grinding, DNA extraction, repurification in the case of highly inhibited samples, quantification, STR multiplex amplification, and profile reporting guidelines. However, the conditions applied for amplification and the criteria for allele calling and profile submission must be based on the results of each laboratory's internal validation experiments involving the type of samples relevant to the project at hand. The methods presented here have permitted large-scale DNA-based identification of persons missing from mass disasters and armed conflict.

  20. Age at menarche as a fitness trait: nonadditive genetic variance detected in a large twin sample.

    PubMed Central

    Treloar, S A; Martin, N G

    1990-01-01

    The etiological role of genotype and environment in recalled age at menarche was examined using an unselected sample of 1,177 MZ and 711 DZ twin pairs aged 18 years and older. The correlation for onset of menarche between MZ twins was .65 +/- .03, and that for DZ pairs was .18 +/- .04, although these differed somewhat between four birth cohorts. Environmental factors were more important in the older cohorts (perhaps because of less reliable recall). Total genotypic variance (additive plus nonadditive) ranged from 61% in the oldest cohort to 68% in the youngest cohort. In the oldest birth cohort (born before 1939), there was evidence of greater influence of environmental factors on age at menarche in the second-born twin, although there was no other evidence in the data that birth trauma affected timing. The greater part of the genetic variance was nonadditive (dominance or epistasis), and this is typical of a fitness trait. It appears that genetic nonadditivity is in the decreasing direction, and this is consistent with selection for early menarche during human evolution. Breakdown of inbreeding depression as a possible explanation for the secular decline in age at menarche is discussed. PMID:2349942

  1. The Gifted Rating Scales-Preschool/Kindergarten Form: An Analysis of the Standardization Sample Based on Age, Gender, and Race

    PubMed Central

    Pfeiffer, Steven L; Petscher, Yaacov; Jarosewich, Tania

    2015-01-01

    This study reports on an analysis of the standardization sample of a rating scale designed to assist in identification of gifted students. The Gifted Rating Scales-Preschool/Kindergarten Form (GRS-P) is based on a multidimensional model of giftedness designed for preschool and kindergarten students. Results provide support for: the internal structure of the scale; no age differences across the 3-year age span 4:0–6:11; gender differences on only one of the five scales; artistic talent; and small but statistically significant race/ethnicity differences with Asian Americans rated, on average, 1.5 scale-score points higher than whites and Native Americans and 7 points higher than African American and Hispanic students. The present findings provide support for the GRS-P as a valid screening test for giftedness. PMID:26346963

  2. Location and Age Database for Selected Foraminifer Samples Collected by Exxon Petroleum Geologists in California

    USGS Publications Warehouse

    Brabb, Earl E.; Parker, John M.

    2003-01-01

    Most of the geologic maps published for central California before 1960 were made without the benefit of age determinations from microfossils. The ages of Cretaceous and Tertiary rocks in the mostly poorly exposed and structurally complex sedimentary rocks represented in the Coast Ranges are critical in determining stratigraphic succession or lack of it, and in determining whether the juxtaposition of similar appearing but different age formations means a fault is present. Since the 1930’s, at least, oil company geologists have used microfossils to assist them in geologic mapping and in determining the environments of deposition of the sediment containing the microfossils. This information has been so confidential that some companies even coded the names of foraminifers to prevent disclosure. In the past 20 years, however, the attitude of petroleum companies about this information has changed, and many of the formerly confidential materials and reports are now available. We report here on 1,964 Exxon foraminifer samples mostly from surface localities in the San Francisco Bay region, and elsewhere in California. Most but not all the samples were plotted on U. S. Geological Survey (USGS) 7.5’ topographic maps or on obsolete USGS 15’ maps. The information from the slides can be used to update geologic maps prepared without the benefit of microfossil data, to analyze the depth and temperature of ocean water covering parts of California during the Mesozoic and Cenozoic Eras, and for solving nomenclature and other scientific problems. A similar report on more than 30,000 slides for surface samples collected by Chevron geologists has been released (Brabb and Parker, 2003), and another report provides information on slides for more than 2000 oil test wells in Northern California (Brabb, Powell, and Brocher, 2001).

  3. Age-Of Dependent Mutation Rate and Weak Children in the Penna Model in Biological Ageing

    NASA Astrophysics Data System (ADS)

    Berntsen, K. Nikolaj

    We investigate the effect of an age-dependent mutation rate in the Penna model of ageing and then we observe that the high mortality for human babies can be reproduced by the model if one assumes babies to be weaker than adults.

  4. How old is this bird? The age distribution under some phase sampling schemes.

    PubMed

    Hautphenne, Sophie; Massaro, Melanie; Taylor, Peter

    2017-04-03

    In this paper, we use a finite-state continuous-time Markov chain with one absorbing state to model an individual's lifetime. Under this model, the time of death follows a phase-type distribution, and the transient states of the Markov chain are known as phases. We then attempt to provide an answer to the simple question "What is the conditional age distribution of the individual, given its current phase"? We show that the answer depends on how we interpret the question, and in particular, on the phase observation scheme under consideration. We then apply our results to the computation of the age pyramid for the endangered Chatham Island black robin Petroica traversi during the monitoring period 2007-2014.

  5. Relations between Executive Function and Academic Achievement from Ages 5 to 17 in a Large, Representative National Sample

    ERIC Educational Resources Information Center

    Best, John R.; Miller, Patricia H.; Naglieri, Jack A.

    2011-01-01

    This study examined age-related changes in complex executive function (EF) in a large, representative sample (N=2036) aged 5 to 17 using the Cognitive Assessment System (CAS; Naglieri & Das, 1997a). Relations between complex EF and academic achievement were examined on a sub-sample (N = 1395) given the Woodcock-Johnson Tests of…

  6. Computer Modelling of Age Hardening for Isothermally Aged Al-Mg-Si Alloys

    NASA Astrophysics Data System (ADS)

    Wu, Linda; Ferguson, W. George

    Computer modelling, due to it saving time and money, has been widely used in industrial simulation. The present model, which is based on the Shercliff-Ashby methodology for the ageing of aluminum alloys, can be used to predict the yield strength (or hardness) of Al-Mg-Si alloys for the artificial ageing temperature below the solvus temperature as a function of time. With suitable input data, this model can be applied to most Al-Mg-Si alloys, wrought or cast. In the present model, input data for aluminium alloys of A356, A357 and 6061 is taken from the open literature, and then the unknown constants are calibrated from these data. After calibration, the ageing curves are constructed for different isothermal ageing temperatures. Finally, experimentally ageing heat treatments at different temperatures for casting alloys of A356 were done to validate the model.

  7. Determination of K-Ar ages in milligram samples using an infrared laser for argon extraction.

    PubMed

    Solé, Jesús

    2009-11-01

    The K-Ar dating method has been used for decades to decipher the ages of terrestrial and extraterrestrial minerals and rocks. The natural radioactive decay of a metal to a rare gas is an advantage that allows the determination of very small amounts of argon by mass spectrometry. Although the Ar-Ar method has superseded K-Ar, the latter is still used and it has room for improvement. One of these is the reduction of the analyzed sample mass, a desideratum of any current analytical technique. I report here our experience in K-Ar geochronology of milligram-sized samples using laser heating and melting for gas extraction. This modification of the classical K-Ar technique has not been, to my knowledge, used in any other laboratory in the world and deserves a detailed description of its advantages and limitations.

  8. Association between Caregiving, Meaning in Life, and Life Satisfaction beyond 50 in an Asian Sample: Age as a Moderator

    ERIC Educational Resources Information Center

    Ang, Rebecca P.; O, Jiaqing

    2012-01-01

    The association between caregiving, meaning in life, and life satisfaction was examined in sample of 519 older Asian adults beyond 50 years of age. Two hierarchical multiple regression analyses were conducted to examine age as moderator of the associations between caregiving, meaning in life, and life satisfaction. Age moderated the association…

  9. Modelling nanofluidic field amplified sample stacking with inhomogeneous surface charge

    NASA Astrophysics Data System (ADS)

    McCallum, Christopher; Pennathur, Sumita

    2015-11-01

    Nanofluidic technology has exceptional applications as a platform for biological sample preconcentration, which will allow for an effective electronic detection method of low concentration analytes. One such preconcentration method is field amplified sample stacking, a capillary electrophoresis technique that utilizes large concentration differences to generate high electric field gradients, causing the sample of interest to form a narrow, concentrated band. Field amplified sample stacking has been shown to work well at the microscale, with models and experiments confirming expected behavior. However, nanofluidics allows for further concentration enhancement due to focusing of the sample ions toward the channel center by the electric double layer. We have developed a two-dimensional model that can be used for both micro- and nanofluidics, fully accounting for the electric double layer. This model has been used to investigate even more complex physics such as the role of inhomogeneous surface charge.

  10. Standing on the Shoulders of Dwarfs: the Kepler Asteroseismic LEGACY Sample. II.Radii, Masses, and Ages

    NASA Astrophysics Data System (ADS)

    Silva Aguirre, Víctor; Lund, Mikkel N.; Antia, H. M.; Ball, Warrick H.; Basu, Sarbani; Christensen-Dalsgaard, Jørgen; Lebreton, Yveline; Reese, Daniel R.; Verma, Kuldeep; Casagrande, Luca; Justesen, Anders B.; Mosumgaard, Jakob R.; Chaplin, William J.; Bedding, Timothy R.; Davies, Guy R.; Handberg, Rasmus; Houdek, Günter; Huber, Daniel; Kjeldsen, Hans; Latham, David W.; White, Timothy R.; Coelho, Hugo R.; Miglio, Andrea; Rendle, Ben

    2017-02-01

    We use asteroseismic data from the Kepler satellite to determine fundamental stellar properties of the 66 main-sequence targets observed for at least one full year by the mission. We distributed tens of individual oscillation frequencies extracted from the time series of each star among seven modeling teams who applied different methods to determine radii, masses, and ages for all stars in the sample. Comparisons among the different results reveal a good level of agreement in all stellar properties, which is remarkable considering the variety of codes, input physics, and analysis methods employed by the different teams. Average uncertainties are of the order of ∼2% in radius, ∼4% in mass, and ∼10% in age, making this the best-characterized sample of main-sequence stars available to date. Our predicted initial abundances and mixing-length parameters are checked against inferences from chemical enrichment laws ΔY/ΔZ and predictions from 3D atmospheric simulations. We test the accuracy of the determined stellar properties by comparing them to the Sun, angular diameter measurements, Gaia parallaxes, and binary evolution, finding excellent agreement in all cases and further confirming the robustness of asteroseismically determined physical parameters of stars when individual frequencies of oscillation are available. Baptised as the Kepler dwarfs LEGACY sample, these stars are the solar-like oscillators with the best asteroseismic properties available for at least another decade. All data used in this analysis and the resulting stellar parameters are made publicly available for the community.

  11. Do gender and age moderate the symptom structure of PTSD? Findings from a national clinical sample of children and adolescents.

    PubMed

    Contractor, Ateka A; Layne, Christopher M; Steinberg, Alan M; Ostrowski, Sarah A; Ford, Julian D; Elhai, Jon D

    2013-12-30

    A substantial body of evidence documents that the frequency and intensity of posttraumatic stress disorder (PTSD) symptoms are linked to such demographic variables as female sex (e.g., Kaplow et al., 2005) and age (e.g., Meiser-Stedman et al., 2008). Considerably less is known about relations between biological sex and age with PTSD's latent factor structure. This study systematically examined the roles that sex and age may play as candidate moderators of the full range of factor structure parameters of an empirically supported five-factor PTSD model (Elhai et al., 2011). The sample included 6591 trauma-exposed children and adolescents selected from the National Child Traumatic Stress Network's Core Data Set. Confirmatory factor analysis using invariance testing (Gregorich, 2006) and comparative fit index difference values (Cheung and Rensvold, 2002) reflected a mixed pattern of test item intercepts across age groups. The adolescent subsample produced lower residual error variances, reflecting less measurement error than the child subsample. Sex did not show a robust moderating effect. We conclude by discussing implications for clinical assessment, theory building, and future research.

  12. Slice sampling technique in Bayesian extreme of gold price modelling

    NASA Astrophysics Data System (ADS)

    Rostami, Mohammad; Adam, Mohd Bakri; Ibrahim, Noor Akma; Yahya, Mohamed Hisham

    2013-09-01

    In this paper, a simulation study of Bayesian extreme values by using Markov Chain Monte Carlo via slice sampling algorithm is implemented. We compared the accuracy of slice sampling with other methods for a Gumbel model. This study revealed that slice sampling algorithm offers more accurate and closer estimates with less RMSE than other methods . Finally we successfully employed this procedure to estimate the parameters of Malaysia extreme gold price from 2000 to 2011.

  13. Space Weathering of Olivine: Samples, Experiments and Modeling

    NASA Technical Reports Server (NTRS)

    Keller, L. P.; Berger, E. L.; Christoffersen, R.

    2016-01-01

    Olivine is a major constituent of chondritic bodies and its response to space weathering processes likely dominates the optical properties of asteroid regoliths (e.g. S- and many C-type asteroids). Analyses of olivine in returned samples and laboratory experiments provide details and insights regarding the mechanisms and rates of space weathering. Analyses of olivine grains from lunar soils and asteroid Itokawa reveal that they display solar wind damaged rims that are typically not amorphized despite long surface exposure ages, which are inferred from solar flare track densities (up to 10 (sup 7 y)). The olivine damaged rim width rapidly approaches approximately 120 nm in approximately 10 (sup 6 y) and then reaches steady-state with longer exposure times. The damaged rims are nanocrystalline with high dislocation densities, but crystalline order exists up to the outermost exposed surface. Sparse nanophase Fe metal inclusions occur in the damaged rims and are believed to be produced during irradiation through preferential sputtering of oxygen from the rims. The observed space weathering effects in lunar and Itokawa olivine grains are difficult to reconcile with laboratory irradiation studies and our numerical models that indicate that olivine surfaces should readily blister and amorphize on relatively short time scales (less than 10 (sup 3 y)). These results suggest that it is not just the ion fluence alone, but other variable, the ion flux that controls the type and extent of irradiation damage that develops in olivine. This flux dependence argues for caution in extrapolating between high flux laboratory experiments and the natural case. Additional measurements, experiments, and modeling are required to resolve the discrepancies among the observations and calculations involving solar wind processing of olivine.

  14. Performance of Random Effects Model Estimators under Complex Sampling Designs

    ERIC Educational Resources Information Center

    Jia, Yue; Stokes, Lynne; Harris, Ian; Wang, Yan

    2011-01-01

    In this article, we consider estimation of parameters of random effects models from samples collected via complex multistage designs. Incorporation of sampling weights is one way to reduce estimation bias due to unequal probabilities of selection. Several weighting methods have been proposed in the literature for estimating the parameters of…

  15. Wake Up Time, Light, and Mood in a Population Sample Age 40-64 Years

    PubMed Central

    Endo, Takuro; Ancoli-Israel, Sonia

    2015-01-01

    Objective Concern that disturbances of sleep and light exposures at night might increase cancer risks have been expressed, but little actual exposure data has been collected. Measurements from a representative population sample were examined to understand the magnitude of in-bed light exposure at night and possible correlates. Methods From 1990 to 1994, a home survey of sleep disorders among adults ages 40-64 was conducted in the City of San Diego California, using stratified representative sampling techniques. Along with questionnaires, sleep logs, and 3-night wrist activity and pulse oximetry measures, bedside illumination was measured with a computer recording system. Questionnaires included the CESD depression scale and a scale of symptoms typical of winter depression. Results Complete data were available from 286 men and women, whose mean in-bed intervals averaged 7 hours and 42 minutes. The mean room illumination during the first part of the night was mean 12.7 lux (median 3.2 lux) and during the last 2 hours in bed averaged 28.7 lux (median 18.9 lux). Nocturnal light exposure was positively correlated with age, male gender, summer season, time in bed, wake-up time, and depressive symptoms. Conclusion Complex bi-directional interactions may take place between sleep disturbances, depression, time in bed, wake-up-time, and in-bed illumination. The most crucial light exposures appear to occur in the last 2 hours in bed, largely after dawn, so daylight exposure may be an important factor. PMID:25866517

  16. Modeling Creep Processes in Aging Polymers

    NASA Astrophysics Data System (ADS)

    Olali, N. V.; Voitovich, L. V.; Zazimko, N. N.; Malezhik, M. P.

    2016-03-01

    The photoelastic method is generalized to creep in hereditary aging materials. Optical-creep curves and mechanical-creep or optical-relaxation curves are used to interpret fringe patterns. For materials with constant Poisson's ratio, it is sufficient to use mechanical- or optical-creep curves for this purpose

  17. Age Integrated Learning: A Theoretical Model.

    ERIC Educational Resources Information Center

    Heckenmueller, Jerome P.; Keller, Ann

    The concept of age integrated learning (AIL) can be derived from Erikson's theory of psychosocial development. Two emphases in his theory that are less well recognized than others are central to Erikson's theory and are the cornerstone of a rationale for AIL. The first is his emphasis on the interdependence of generations for optimal crisis…

  18. Bacterial and fungal communities in Pu'er tea samples of different ages.

    PubMed

    Tian, Jianqing; Zhu, Zixiang; Wu, Bing; Wang, Lin; Liu, Xingzhong

    2013-08-01

    Pu'er is a major kind of postfermented tea and is made with a "large leaf" variety of Camellia sinensis (C. sinensis assamica), whose distribution is limited to the mountains of southern Yunnan, China. The quality of Pu'er tea is believed to increase with storage (aging, maturing) because of postfermentation by microbes. The effect of storage period (from < 1 to 192 mo) on the bacteria and fungi in Pu'er tea was investigated by a culture-dependent and a PCR-DGGE method. The individual numbers of fungi and bacteria decreased with increasing storage time and were significantly greater in ripened tea than in raw Pu'er tea. Both methods indicated that yeast, Aspergillus spp., and Penicillium spp. were the dominant fungi in almost all the samples. However, the common bacteria detected by the culture-dependent method were species of Pseudomonas, Achromobacter, Alcaligenes, Sporosarcina, and Bacillus, whereas those detected by PCR-DGGE were species of Staphylococcus, Arthrobacter, and Streptomyces. According to ordination analysis, bacterial community structure differed between ripened and raw Pu'er tea. Bacterial diversity was positively correlated with aging time, while fungal diversity in both raw and ripened tea increased during the first 60 mo of aging and then decreased. Changes in polyphenol content were correlated with the changes in fungal diversity. These results suggest that the relationship between storage time and the quality of Pu'er tea is complex and involves changes in polyphenol content and microbial abundance and diversity.

  19. The use of age-clustered pooled faecal samples for monitoring worm control in horses.

    PubMed

    Eysker, M; Bakker, J; van den Berg, M; van Doorn, D C K; Ploeger, H W

    2008-02-14

    A study was performed on two horse farms to evaluate the use of age-clustered pooled faecal samples for monitoring worm control in horses. In total 109 horses, 57 on farm A and 52 on farm B, were monitored at weekly intervals between 6 and 14 weeks after ivermectin treatment. This was performed through pooled faecal samples of pools of up to 10 horses of the groups 'yearlings' (both farms), '2-year-old' (two pools in farm A), '3-year-old' (farm A) and adult horses (four pools on farm A and five pools on farm B), which were compared with the mean individual faecal egg counts of the same pools. A very high correlation between the faecal egg counts in pooled samples and the mean faecal egg counts was seen and also between the faecal egg counts in pooled samples and larval counts from pooled faecal larval cultures. Faecal egg counts increased more rapidly in yearlings and 2-year-old horses than in older horses. This implied that in these groups of young animals faecal egg counts of more than 200 EPG were reached at or just after the egg reappearance period (ERP) of 8 weeks that is usually indicated for ivermectin. This probably means that, certainly under intensive conditions, repeated treatment at this ERP is warranted in these young animals, with or without monitoring through faecal examination. A different situation is seen in adult animals. Based on the mean faecal egg counts on both farms and on the results of pooled samples in farm A, using 100 EPG as threshold, no justification for treatment was seen throughout the experimental period. However, on farm B values of 100 EPG were seen at 9 and 11, 13 and 14 and 14 weeks after ivermectin treatment in pools 10, 12 and 13, respectively. This coincided with the presence of one or two horses with egg counts above 200 EPG. The conclusion is that random pooled faecal samples of 10 adult horses from a larger herd, starting at the ERP and repeating it at, for instance, 4-week intervals, could be used for decisions on worm

  20. Radiochronological Age of a Uranium Metal Sample from an Abandoned Facility

    SciTech Connect

    Meyers, L A; Williams, R W; Glover, S E; LaMont, S P; Stalcup, A M; Spitz, H B

    2012-03-16

    A piece of scrap uranium metal bar buried in the dirt floor of an old, abandoned metal rolling mill was analyzed using multi-collector inductively coupled plasma mass spectroscopy (MC-ICP-MS). The mill rolled uranium rods in the 1940s and 1950s. Samples of the contaminated dirt in which the bar was buried were also analyzed. The isotopic composition of uranium in the bar and dirt samples were both the same as natural uranium, though a few samples of dirt also contained recycled uranium; likely a result of contamination with other material rolled at the mill. The time elapsed since the uranium metal bar was last purified can be determined by the in-growth of the isotope {sup 230}Th from the decay of {sup 234}U, assuming that only uranium isotopes were present in the bar after purification. The age of the metal bar was determined to be 61 years at the time of this analysis and corresponds to a purification date of July 1950 {+-} 1.5 years.

  1. Age and gender specific biokinetic model for strontium in humans.

    PubMed

    Shagina, N B; Tolstykh, E I; Degteva, M O; Anspaugh, L R; Napier, B A

    2015-03-01

    A biokinetic model for strontium in humans is necessary for quantification of internal doses due to strontium radioisotopes. The ICRP-recommended biokinetic model for strontium has limitations for use in a population study, because it is not gender specific and does not cover all age ranges. The extensive Techa River data set on (90)Sr in humans (tens of thousands of measurements) is a unique source of data on long-term strontium retention for men and women of all ages at intake. These, as well as published data, were used for evaluation of age- and gender-specific parameters for a new compartment biokinetic model for strontium (Sr-AGe model). The Sr-AGe model has a similar structure to the ICRP model for the alkaline earth elements. The following parameters were mainly re-evaluated: gastrointestinal absorption and parameters related to the processes of bone formation and resorption defining calcium and strontium transfers in skeletal compartments. The Sr-AGe model satisfactorily describes available data sets on strontium retention for different kinds of intake (dietary and intravenous) at different ages (0-80 years old) and demonstrates good agreement with data sets for different ethnic groups. The Sr-AGe model can be used for dose assessment in epidemiological studies of general populations exposed to ingested strontium radioisotopes.

  2. Age and gender specific biokinetic model for strontium in humans

    SciTech Connect

    Shagina, N. B.; Tolstykh, E. I.; Degteva, M. O.; Anspaugh, L. R.; Napier, Bruce A.

    2015-03-01

    A biokinetic model for strontium in humans is necessary for quantification of internal doses due to strontium radioisotopes. The ICRP-recommended biokinetic model for strontium has limitation for use in a population study, because it is not gender specific and does not cover all age ranges. The extensive Techa River data set on 90Sr in humans (tens of thousands of measurements) is a unique source of data on long-term strontium retention for men and women of all ages at intake. These, as well as published data, were used for evaluation of age- and gender-specific parameters for a new compartment biokinetic model for strontium (Sr-AGe model). The Sr-AGe model has similar structure as the ICRP model for the alkaline earth elements. The following parameters were mainly reevaluated: gastro-intestinal absorption and parameters related to the processes of bone formation and resorption defining calcium and strontium transfers in skeletal compartments. The Sr-AGe model satisfactorily describes available data sets on strontium retention for different kinds of intake (dietary and intravenous) at different ages (0–80 years old) and demonstrates good agreement with data sets for different ethnic groups. The Sr-AGe model can be used for dose assessment in epidemiological studies of general population exposed to ingested strontium radioisotopes.

  3. Dynamical Masses of Young Stars. I. Discordant Model Ages of Upper Scorpius

    NASA Astrophysics Data System (ADS)

    Rizzuto, Aaron C.; Ireland, Michael J.; Dupuy, Trent J.; Kraus, Adam L.

    2016-02-01

    We present the results of a long-term orbit monitoring program, using sparse aperture masking observations taken with NIRC2 on the Keck-II telescope, of seven G- to M-type members of the Upper Scorpius subgroup of the Sco-Cen OB association. We present astrometry and derived orbital elements of the binary systems we have monitored, and also determine the age, component masses, distance, and reddening for each system using the orbital solutions and multi-band photometry, including Hubble Space Telescope photometry, and a Bayesian fitting procedure. We find that the models can be forced into agreement with any individual system by assuming an age, but that age is not consistent across the mass range of our sample. The G-type binary systems in our sample have model ages of ˜11.5 Myr, which is consistent with the latest age estimates for Upper Scorpius, while the M-type binary systems have significantly younger model ages of ˜7 Myr. Based on our fits, this age discrepancy in the models corresponds to a luminosity underprediction of 0.8-0.15 dex, or equivalently an effective temperature overprediction of 100-300 K for M-type stars at a given pre-main-sequence age. We also find that the M-type binary system RXJ 1550.0-2312 has an age (˜16 Myr) and distance (˜85 pc) consistent with membership in the Upper Centaurus Lupus subgroup.

  4. Clustered drug and sexual HIV risk among a sample of middle-aged injection drug users, Houston, Texas.

    PubMed

    Noor, Syed W B; Ross, Michael W; Lai, Dejian; Risser, Jan M

    2013-01-01

    Recent studies have reported a clustered pattern of high-risk drug using and sexual behaviors among younger injection drug users (IDUs), however, no studies have looked at this clustering pattern in relatively older IDUs. This analysis examines the interplay and overlap of drug and sexual HIV risk among a sample of middle-aged, long-term IDUs in Houston, Texas. Our study includes 452 eligible IDUs, recruited into the 2009 National HIV Behavioral Surveillance project. Four separate multiple logistic regression models were built to examine the odds of reporting a given risk behavior. We constructed the most parsimonious multiple logistic regression model using a manual backward stepwise process. Participants were mostly male, older (mean age: 49.5±6.63), and nonHispanic Black. Prevalence of receptive needle sharing as well as having multiple sex partners and having unprotected sex with a partner in exchange for money, drugs, or other things at last sex were high. Unsafe injecting practices were associated with high-risk sexual behaviors. IDUs, who used a needle after someone else had injected with it had higher odds of having more than three sex partners (odds ratio (OR) = 2.10, 95% confidence interval (CI): 1.40-3.12) in last year and who shared drug preparation equipment had higher odds of having unprotected sex with an exchange partner (OR = 3.89, 95% CI: 1.66-9.09) at last sex. Additionally, homelessness was associated with unsafe injecting practices but not with high-risk sexual behaviors. Our results show that a majority of the sample IDUs are practicing sexual as well as drug-using HIV risk behaviors. The observed clustering pattern of drug and sexual risk behavior among this middle-aged population is alarming and deserve attention of HIV policy-makers and planners.

  5. Precision of the age-length increments of three cyprinids: effects of fish number and sub-sampling strategy.

    PubMed

    Busst, G M; Britton, J R

    2014-06-01

    The effects of number of fish that are aged and scale sub-sampling strategies on the precision of estimates of mean age-length increments from populations of Rutilus rutilus, Leuciscus leuciscus and Leuciscus cephalus were tested. Analyses used data derived from river fish communities in eastern England, U.K.. Regarding the number of fishes analysed in each age group, for each species and mean fork-length increment at age, significant relationships were detected between sample size (n) and the coefficient of variation of the mean (Z) and mean length increment x‾ and measured variance (s(2)). This enabled calculation of the number of scales for producing a mean length increment at age according to n=ax‾(b(-2))Zx‾(-2). Outputs indicated that the number of scales requiring ageing increased substantially as precision increased, but with little variation between species per age category. Ageing between seven and 12 scales per age group would thus provide estimates at 10% precision. As the ages of fishes are not known in advance of scale ageing, the effect of scale sub-sampling regime on precision was also tested using randomized strategies of 10 fish per 5 mm, five per 5 mm, three per 5 mm, 10 per 10 mm, five per 10 mm and three per 10 mm. These were applied to the datasets and the consequences of their reduction in the number of scales for precision were determined using Z=a(0.5)x‾((b/2)(-1))n(-0.5). When compared to no sub-sampling, three per 10 mm always significantly reduced data precision, whereas 10 per 5 mm never significantly reduced precision. These outputs can thus be applied to the design of fish sampling protocols where age and growth estimates are required, with the randomized sub-sampling likely to be the most useful strategy.

  6. Small Sample Properties of Bayesian Multivariate Autoregressive Time Series Models

    ERIC Educational Resources Information Center

    Price, Larry R.

    2012-01-01

    The aim of this study was to compare the small sample (N = 1, 3, 5, 10, 15) performance of a Bayesian multivariate vector autoregressive (BVAR-SEM) time series model relative to frequentist power and parameter estimation bias. A multivariate autoregressive model was developed based on correlated autoregressive time series vectors of varying…

  7. Bayesian Estimation of the DINA Model with Gibbs Sampling

    ERIC Educational Resources Information Center

    Culpepper, Steven Andrew

    2015-01-01

    A Bayesian model formulation of the deterministic inputs, noisy "and" gate (DINA) model is presented. Gibbs sampling is employed to simulate from the joint posterior distribution of item guessing and slipping parameters, subject attribute parameters, and latent class probabilities. The procedure extends concepts in Béguin and Glas,…

  8. Scaled tests and modeling of effluent stack sampling location mixing.

    PubMed

    Recknagle, Kurtis P; Yokuda, Satoru T; Ballinger, Marcel Y; Barnett, J Matthew

    2009-02-01

    A three-dimensional computational fluid dynamics computer model was used to evaluate the mixing at a sampling system for radioactive air emissions. Researchers sought to determine whether the location would meet the criteria for uniform air velocity and contaminant concentration as prescribed in the American National Standards Institute standard, Sampling and Monitoring Releases of Airborne Radioactive Substances from the Stacks and Ducts of Nuclear Facilities. This standard requires that the sampling location be well-mixed and stipulates specific tests to verify the extent of mixing. The exhaust system for the Radiochemical Processing Laboratory was modeled with a computational fluid dynamics code to better understand the flow and contaminant mixing and to predict mixing test results. The modeled results were compared to actual measurements made at a scale-model stack and to the limited data set for the full-scale facility stack. Results indicated that the computational fluid dynamics code provides reasonable predictions for velocity, cyclonic flow, gas, and aerosol uniformity, although the code predicts greater improvement in mixing as the injection point is moved farther away from the sampling location than is actually observed by measurements. In expanding from small to full scale, the modeled predictions for full-scale measurements show similar uniformity values as in the scale model. This work indicated that a computational fluid dynamics code can be a cost-effective aid in designing or retrofitting a facility's stack sampling location that will be required to meet standard ANSI/HPS N13.1-1999.

  9. Latent spatial models and sampling design for landscape genetics

    USGS Publications Warehouse

    Hanks, Ephraim M.; Hooten, Mevin B.; Knick, Steven T.; Oyler-McCance, Sara J.; Fike, Jennifer A.; Cross, Todd B.; Schwartz, Michael K.

    2016-01-01

    We propose a spatially-explicit approach for modeling genetic variation across space and illustrate how this approach can be used to optimize spatial prediction and sampling design for landscape genetic data. We propose a multinomial data model for categorical microsatellite allele data commonly used in landscape genetic studies, and introduce a latent spatial random effect to allow for spatial correlation between genetic observations. We illustrate how modern dimension reduction approaches to spatial statistics can allow for efficient computation in landscape genetic statistical models covering large spatial domains. We apply our approach to propose a retrospective spatial sampling design for greater sage-grouse (Centrocercus urophasianus) population genetics in the western United States.

  10. RNA modeling using Gibbs sampling and stochastic context free grammars

    SciTech Connect

    Grate, L.; Herbster, M.; Rughey, R.; Haussler, D.

    1994-12-31

    A new method of discovering the common secondary structure of a family of homologous RNA sequences using Gibbs sampling and stochastic context-free grammars is proposed. Given an unaligned set of sequences, a Gibbs sampling step simultaneously estimates the secondary structure of each sequence and a set of statistical parameters describing the common secondary structure of the set as a whole. These parameters describe a statistical model of the family. After the Gibbs sampling has produced a crude statistical model for the family, this model is translated into a stochastic context-free grammar, which is then refined by an Expectation Maximization (EM) procedure to produce a more complete model. A prototype implementation of the method is tested on tRNA, pieces of 16S rRNA and on U5 snRNA with good results.

  11. Cusp Catastrophe Polynomial Model: Power and Sample Size Estimation

    PubMed Central

    Chen, Ding-Geng(Din); Chen, Xinguang(Jim); Lin, Feng; Tang, Wan; Lio, Y. L.; Guo, (Tammy) Yuanyuan

    2016-01-01

    Guastello’s polynomial regression method for solving cusp catastrophe model has been widely applied to analyze nonlinear behavior outcomes. However, no statistical power analysis for this modeling approach has been reported probably due to the complex nature of the cusp catastrophe model. Since statistical power analysis is essential for research design, we propose a novel method in this paper to fill in the gap. The method is simulation-based and can be used to calculate statistical power and sample size when Guastello’s polynomial regression method is used to cusp catastrophe modeling analysis. With this novel approach, a power curve is produced first to depict the relationship between statistical power and samples size under different model specifications. This power curve is then used to determine sample size required for specified statistical power. We verify the method first through four scenarios generated through Monte Carlo simulations, and followed by an application of the method with real published data in modeling early sexual initiation among young adolescents. Findings of our study suggest that this simulation-based power analysis method can be used to estimate sample size and statistical power for Guastello’s polynomial regression method in cusp catastrophe modeling. PMID:27158562

  12. Factors associated with constipation in a community based sample of people aged 70 years and over.

    PubMed Central

    Campbell, A J; Busby, W J; Horwath, C C

    1993-01-01

    STUDY OBJECTIVE--The aim was to determine the prevalence and factors associated with constipation in elderly people. DESIGN--The study was a survey involving administration of a structured questionnaire, an interview, and a dietary assessment. SETTING--The survey was community based and the population studied was drawn from the practice records of all five general practitioners serving a rural township of 13,500 people. PARTICIPANTS--778 (91.8%) of the 856 people aged 70 years and over registered with the five practitioners took part. MAIN RESULTS--174 subjects had symptoms of infrequent bowel motions or frequent straining at stool or used laxatives regularly. Of this group, 34 had a bowel motion only every 3 d or less frequently and were considered to have constipation. Analysis of this subgroup showed that constipation was more common in women than men, increased with age, and was associated with the use of constipating drugs. Those whose bowels moved infrequently were a more frail group who were less physically active. Low intakes of dietary fibre, fruit, vegetables, bread and cereals, or fluid were not associated with an increased occurrence of constipation. There were 151 subjects who felt they were moderately constipated, but who had a bowel motion at least every 2 d. These people were more likely than the rest of the sample to use laxatives (55.6%), were more likely to take food for their bowels, to take hynoptics, and to regard their health as poor. CONCLUSIONS--About one third of people aged 70 years and over have some bowel problem such as infrequency, straining at stool, or frequent laxative use. Most modify their diet accordingly but laxative use remains high. PMID:8382251

  13. Applicability of Willems model for dental age estimations in Brazilian children.

    PubMed

    Franco, Ademir; Thevissen, Patrick; Fieuws, Steffen; Souza, Paulo Henrique Couto; Willems, Guy

    2013-09-10

    Several studies described tooth development as a reliable pathway for age estimations. Depending on the considered life span, the dental age indicators vary. In children, combinations of developing teeth provide the best information about age. In sub adults third molar mineralization is almost exclusively considered. The aim of this study was, firstly, to verify the Willems model in a Brazilian sample. Secondly, to observe differences between the Willems model and a new developed Brazilian model. Thirdly, the information of permanent teeth (PM) and third molar (TM), development was combined for age estimation in children. A sample of 1357 panoramic radiographs of Brazilian males (M) and females (F), with age between 5 and 23 years was collected. The technique of Gleiser and Hunt modified by Kohler (1955) [34] was applied for third molar staging in the entire sample. The Demirjian staging technique was used on the mandibular left permanent teeth (except third molars) of all individuals from 5 to 15 years. Kappa and weighted Kappa statistics were performed to verify inter- and intra-observer reliabilities. Based on the obtained Demirjian scores the Willems model was verified. Next the data were split to develop a new Brazilian model based on the Willems method and to verify the established model. The accuracy in age prediction between the Willems model and the new Brazilian model was compared. Additionally, regression models including PM, TM and PM plus TM information were compared. The Kappa and weighted Kappa statistics revealed high agreement between observers (0.88 Kappa; 0.93 weighted Kappa). The differences between predicted and chronological age for the verified Willems model were expressed in mean errors of -0.17 and -0.38 year for F and M respectively. The differences in mean error between the new developed Brazilian model and the Willems model were 0.02 (F) and 0.20 (M) year. The regression models combining PT and TM information provided only in the age

  14. An Age-Graded Model for Career Development Education.

    ERIC Educational Resources Information Center

    Tuckman, Bruce W.

    This paper presents a career developmental model covering the ages of 5 to 18. Career development education includes experiences which facilitate self-awareness, career-awareness and career decision-making. Before choosing a model for career development, it is necessary to decide on a model for child development. The model developed here borrows…

  15. An integrated modeling approach to age invariant face recognition

    NASA Astrophysics Data System (ADS)

    Alvi, Fahad Bashir; Pears, Russel

    2015-03-01

    This Research study proposes a novel method for face recognition based on Anthropometric features that make use of an integrated approach comprising of a global and personalized models. The system is aimed to at situations where lighting, illumination, and pose variations cause problems in face recognition. A Personalized model covers the individual aging patterns while a Global model captures general aging patterns in the database. We introduced a de-aging factor that de-ages each individual in the database test and training sets. We used the k nearest neighbor approach for building a personalized model and global model. Regression analysis was applied to build the models. During the test phase, we resort to voting on different features. We used FG-Net database for checking the results of our technique and achieved 65 percent Rank 1 identification rate.

  16. The Gifted Rating Scales-School Form: An Analysis of the Standardization Sample Based on Age, Gender, Race, and Diagnostic Efficiency

    ERIC Educational Resources Information Center

    Pfeiffer, Steven I.; Jarosewich, Tania

    2007-01-01

    This study analyzes the standardization sample of a new teacher rating scale designed to assist in the identification of gifted students. The Gifted Rating Scales-School Form (GRS-S) is based on a multidimensional model of giftedness. Results indicate no age or race/ethnicity differences on any of the scales and small but significant differences…

  17. Aging and symptoms of anxiety and depression: structural invariance of the tripartite model.

    PubMed

    Teachman, Bethany A; Siedlecki, Karen L; Magee, Joshua C

    2007-03-01

    Negative affect measures were evaluated in a cross-sectional community sample of adults aged 18-93 (N = 335) to examine the structure of neuroticism, anxiety, and depressive symptoms in young, middle, and older adult cohorts. Structural equation modeling was used to contrast 3 nested models: a 1-factor general distress model; a 2-factor high negative-low positive affect model; and a 3-factor "tripartite model" reflecting a higher order Negative Affect factor that is common to depression and anxiety problems and 2 lower order factors, Low Positive Affect (mostly specific to depression) and Arousal (specific to anxiety/panic). As expected, the tripartite model fit best for all age groups. Further, multigroup analyses indicated age invariance for the tripartite model, suggesting the model can be effectively applied with older populations.

  18. Exploring the power of yeast to model aging and age-related neurodegenerative disorders.

    PubMed

    Oliveira, Ana V; Vilaça, Rita; Santos, Cláudia N; Costa, Vítor; Menezes, Regina

    2017-02-01

    Aging is a multifactorial process determined by molecular, cellular and systemic factors and it is well established that advancing age is a leading risk factor for several neurodegenerative diseases. In fact, the close association of aging and neurodegenerative disorders has placed aging as the greatest social and economic challenge of the 21st century, and age-related diseases have also become a key priority for countries worldwide. The growing need to better understand both aging and neurodegenerative processes has led to the development of simple eukaryotic models amenable for mechanistic studies. Saccharomyces cerevisiae has proven to be an unprecedented experimental model to study the fundamental aspects of aging and to decipher the intricacies of neurodegenerative disorders greatly because the molecular mechanisms underlying these processes are evolutionarily conserved from yeast to human. Moreover, yeast offers several methodological advantages allowing a rapid and relatively easy way of establishing gene-protein-function associations. Here we review different aging theories, common cellular pathways driving aging and neurodegenerative diseases and discuss the major contributions of yeast to the state-of-art knowledge in both research fields.

  19. Cerebrovascular hemodynamic correlates of aging in the Lou/c rat: a model of healthy aging.

    PubMed

    Dubeau, S; Ferland, G; Gaudreau, P; Beaumont, E; Lesage, F

    2011-06-15

    The LOU/c rat is an inbred strain considered a model of healthy aging. It exhibits a longer free disease lifespan and a low adiposity throughout life. While this animal model has been shown to maintain eating behavior and neuroendocrine, metabolic and cognitive functions with age, no study has yet investigated vascular correlates in this model of healthy aging. In the present work, multispectral optical imaging was used to investigate the hemodynamic response in the somatosensory cortex of LOU/c rats following forepaw stimulation in three age groups, 4, 24 and 40months. Results indicate reduced hemodynamic responses in the contralateral somatosensory cortex between young (4months) and older groups following stimulation. This decrease was associated with an increase in the spatial extent of activation. The ipsilateral response did not change with aging leading to decreased laterality. Estimations of the relative change in the local cerebral metabolic rate of oxygen during stimulation based on multimodal data showed no significant change with age. The exponent describing the relation between blood volume and blood flow changes, Grubb's parameter, did display a significant change with age which may suggest vessel compliance modifications. This work finds its relevance in recent findings underlying the importance of vascular changes with aging and its impact on neurodegenerative disease.

  20. Numerical solution of the Penna model of biological aging with age-modified mutation rate

    NASA Astrophysics Data System (ADS)

    Magdoń-Maksymowicz, M. S.; Maksymowicz, A. Z.

    2009-06-01

    In this paper we present results of numerical calculation of the Penna bit-string model of biological aging, modified for the case of a -dependent mutation rate m(a) , where a is the parent’s age. The mutation rate m(a) is the probability per bit of an extra bad mutation introduced in offspring inherited genome. We assume that m(a) increases with age a . As compared with the reference case of the standard Penna model based on a constant mutation rate m , the dynamics of the population growth shows distinct changes in age distribution of the population. Here we concentrate on mortality q(a) , a fraction of items eliminated from the population when we go from age (a) to (a+1) in simulated transition from time (t) to next time (t+1) . The experimentally observed q(a) dependence essentially follows the Gompertz exponential law for a above the minimum reproduction age. Deviation from the Gompertz law is however observed for the very old items, close to the maximal age. This effect may also result from an increase in mutation rate m with age a discussed in this paper. The numerical calculations are based on analytical solution of the Penna model, presented in a series of papers by Coe [J. B. Coe, Y. Mao, and M. E. Cates, Phys. Rev. Lett. 89, 288103 (2002)]. Results of the numerical calculations are supported by the data obtained from computer simulation based on the solution by Coe

  1. [Bacterial isolates from respiratory samples of pediatric patients with cystic fibrosis and their distribution by ages].

    PubMed

    Busquets, Natalia P; Baroni, María R; Ochoteco, María C; Zurbriggen, María L; Virgolini, Stella; Meneghetti, Fernando G

    2013-01-01

    The bacterial isolates from respiratory samples of 50 pediatric patients with cystic fibrosis, their distribution by ages and antimicrobial resistance pattern as well as the intermittence of isolations and coinfections, were investigated. Staphylococcus aureus was isolated in 72 % of patients, followed by Pseudomonas aeruginosa (58 %), Haemophilus. influenzae (56 %), and the Burkholderia cepacia complex (12 %). The frequency of resistance of P. aeruginosa isolates to β-lactam antibiotics was low (13.8 %). Fifty percent of S. aureus isolates was methicillin-resistant, and 57.1 % of H. influenza was ampicillin resistant due to β-lactamase production. In children under 4 years-old, S. aureus was predominant, followed by P. aeruginosa and H. influenzae. This order of predominance was observed in all the groups studied, except in that of children between 10 and 14 years-old. Stenotrophomonas maltophilia and Achromobacter xylosoxidans isolates were intermittent and accompanied by other microorganisms. Finally, we observed a great variety of bacterial species, which imposes stringent performance requirements for microbiological studies in all respiratory samples of these patients.

  2. A comprehensive approach to age-dependent dosimetric modeling

    SciTech Connect

    Leggett, R.W.; Cristy, M.; Eckerman, K.F.

    1986-01-01

    In the absence of age-specific biokinetic models, current retention models of the International Commission on Radiological Protection (ICRP) frequently are used as a point of departure for evaluation of exposures to the general population. These models were designed and intended for estimation of long-term integrated doses to the adult worker. Their format and empirical basis preclude incorporation of much valuable physiological information and physiologically reasonable assumptions that could be used in characterizing the age-specific behavior of radioelements in humans. In this paper we discuss a comprehensive approach to age-dependent dosimetric modeling in which consideration is given not only to changes with age in masses and relative geometries of body organs and tissues but also to best available physiological and radiobiological information relating to the age-specific biobehavior of radionuclides. This approach is useful in obtaining more accurate estimates of long-term dose commitments as a function of age at intake, but it may be particularly valuable in establishing more accurate estimates of dose rate as a function of age. Age-specific dose rates are needed for a proper analysis of the potential effects on estimates or risk of elevated dose rates per unit intake in certain stages of life, elevated response per unit dose received during some stages of life, and age-specific non-radiogenic competing risks.

  3. Lithium battery aging model based on Dakin's degradation approach

    NASA Astrophysics Data System (ADS)

    Baghdadi, Issam; Briat, Olivier; Delétage, Jean-Yves; Gyan, Philippe; Vinassa, Jean-Michel

    2016-09-01

    This paper proposes and validates a calendar and power cycling aging model for two different lithium battery technologies. The model development is based on previous SIMCAL and SIMSTOCK project data. In these previous projects, the effect of the battery state of charge, temperature and current magnitude on aging was studied on a large panel of different battery chemistries. In this work, data are analyzed using Dakin's degradation approach. In fact, the logarithms of battery capacity fade and the increase in resistance evolves linearly over aging. The slopes identified from straight lines correspond to battery aging rates. Thus, a battery aging rate expression function of aging factors was deduced and found to be governed by Eyring's law. The proposed model simulates the capacity fade and resistance increase as functions of the influencing aging factors. Its expansion using Taylor series was consistent with semi-empirical models based on the square root of time, which are widely studied in the literature. Finally, the influence of the current magnitude and temperature on aging was simulated. Interestingly, the aging rate highly increases with decreasing and increasing temperature for the ranges of -5 °C-25 °C and 25 °C-60 °C, respectively.

  4. An open-population hierarchical distance sampling model

    USGS Publications Warehouse

    Sollmann, Rachel; Beth Gardner,; Richard B Chandler,; Royle, J. Andrew; T Scott Sillett,

    2015-01-01

    Modeling population dynamics while accounting for imperfect detection is essential to monitoring programs. Distance sampling allows estimating population size while accounting for imperfect detection, but existing methods do not allow for direct estimation of demographic parameters. We develop a model that uses temporal correlation in abundance arising from underlying population dynamics to estimate demographic parameters from repeated distance sampling surveys. Using a simulation study motivated by designing a monitoring program for island scrub-jays (Aphelocoma insularis), we investigated the power of this model to detect population trends. We generated temporally autocorrelated abundance and distance sampling data over six surveys, using population rates of change of 0.95 and 0.90. We fit the data generating Markovian model and a mis-specified model with a log-linear time effect on abundance, and derived post hoc trend estimates from a model estimating abundance for each survey separately. We performed these analyses for varying number of survey points. Power to detect population changes was consistently greater under the Markov model than under the alternatives, particularly for reduced numbers of survey points. The model can readily be extended to more complex demographic processes than considered in our simulations. This novel framework can be widely adopted for wildlife population monitoring.

  5. 230Th-234U Model-Ages of Some Uranium Standard Reference Materials

    SciTech Connect

    Williams, R W; Gaffney, A M; Kristo, M J; Hutcheon, I D

    2009-05-28

    The 'age' of a sample of uranium is an important aspect of a nuclear forensic investigation and of the attribution of the material to its source. To the extent that the sample obeys the standard rules of radiochronometry, then the production ages of even very recent material can be determined using the {sup 230}Th-{sup 234}U chronometer. These standard rules may be summarized as (a) the daughter/parent ratio at time=zero must be known, and (b) there has been no daughter/parent fractionation since production. For most samples of uranium, the 'ages' determined using this chronometer are semantically 'model-ages' because (a) some assumption of the initial {sup 230}Th content in the sample is required and (b) closed-system behavior is assumed. The uranium standard reference materials originally prepared and distributed by the former US National Bureau of Standards and now distributed by New Brunswick Laboratory as certified reference materials (NBS SRM = NBL CRM) are good candidates for samples where both rules are met. The U isotopic standards have known purification and production dates, and closed-system behavior in the solid form (U{sub 3}O{sub 8}) may be assumed with confidence. We present here {sup 230}Th-{sup 234}U model-ages for several of these standards, determined by isotope dilution mass spectrometry using a multicollector ICP-MS, and compare these ages with their known production history.

  6. Using remotely-sensed multispectral imagery to build age models for alluvial fan surfaces

    NASA Astrophysics Data System (ADS)

    D'Arcy, Mitch; Mason, Philippa J.; Roda Boluda, Duna C.; Whittaker, Alexander C.; Lewis, James

    2016-04-01

    Accurate exposure age models are essential for much geomorphological field research, and generally depend on laboratory analyses such as radiocarbon, cosmogenic nuclide, or luminescence techniques. These approaches continue to revolutionise geomorphology, however they cannot be deployed remotely or in situ in the field. Therefore other methods are still needed for producing preliminary age models, performing relative dating of surfaces, or selecting sampling sites for the laboratory analyses above. With the widespread availability of detailed multispectral imagery, a promising approach is to use remotely-sensed data to discriminate surfaces with different ages. Here, we use new Landsat 8 Operational Land Imager (OLI) multispectral imagery to characterise the reflectance of 35 alluvial fan surfaces in the semi-arid Owens Valley, California. Alluvial fans are useful landforms to date, as they are widely used to study the effects of tectonics, climate and sediment transport processes on source-to-sink sedimentation. Our target fan surfaces have all been mapped in detail in the field, and have well-constrained exposure ages ranging from modern to ~ 125 ka measured using a high density of 10Be cosmogenic nuclide samples. Despite all having similar granitic compositions, the spectral properties of these surfaces vary systematically with their exposure ages. Older surfaces demonstrate a predictable shift in reflectance across the visible and short-wave infrared spectrum. Simple calculations, such as the brightness ratios of different wavelengths, generate sensitive power law relationships with exposure age that depend on post-depositional alteration processes affecting these surfaces. We investigate what these processes might be in this dryland location, and evaluate the potential for using remotely-sensed multispectral imagery for developing surface age models. The ability to remotely sense relative exposure ages has useful implications for preliminary mapping, selecting

  7. Age constraints on basalt samples from a transect across the Lau Basin: supporting evidence for modification by multiple mantle sources.

    NASA Astrophysics Data System (ADS)

    Conatser, C. S.; Koppers, A. A. P.; Jackson, M. G.; Konter, J. G.; Price, A. A.; Konrad, K.

    2014-12-01

    The tectonic activity of the Lau and North Fiji backarc basins in the South Pacific is complex and not well delimited. Rapid subduction of the Pacific plate at the Tonga trench, together with rifting between the Tonga and Australian plates and Niuafo'ou microplate, has created multiple types of volcanic activity as a function of this complex tectonic setting (1). In addition to extensional volcanism producing depleted mantle melt (2), a number of hotspots (Samoa, Rurutu, Rarotonga, Macdonald and Louisville) have passed near the area, each at distinct time periods, possibly contributing mantle plume components to the magmatism of the Lau Basin. During the summer of 2013, three transects in the Lau Basin and southwest of Samoa were dredged onboard the R/V Roger Revelle (Expedition RR1310). We present here the results of 10 new step heating experiments by the 40Ar/39Ar method using the ARGUS-VI multi-collector mass spectrometer, comprising groundmass and plagioclase separates from 9 basalt samples. These high-precision 40Ar/39Ar ages will allow us to determine whether some of the volcanic activity in the Lau Basin correlates with known ages of hotspot transits through the area, clarifying evidence from corresponding geochemical analyses for a subset of these samples, which support incorporation of Samoan (EMII), Rurutu (HIMU), and Rarotonga (EMI) mantle components into spreading center volcanism across a larger area than previously reported (presented by Price et al., this volume). These ages thus provide insights into the complex construction of the Lau Basin through time. 1. Zellmer, K.E.; Taylor, B. (2001). "A three-plate kinematic model for Lau Basin opening." Geochem., Geophys., Geosyst. 2 (5): 1020 2. F. and B. Taylor. 2002. "Mantle Wedge Control on Back-Arc Crustal Accretion." Nature 416 (6879): 417-420.

  8. Modeling the brain morphology distribution in the general aging population

    NASA Astrophysics Data System (ADS)

    Huizinga, W.; Poot, D. H. J.; Roshchupkin, G.; Bron, E. E.; Ikram, M. A.; Vernooij, M. W.; Rueckert, D.; Niessen, W. J.; Klein, S.

    2016-03-01

    Both normal aging and neurodegenerative diseases such as Alzheimer's disease cause morphological changes of the brain. To better distinguish between normal and abnormal cases, it is necessary to model changes in brain morphology owing to normal aging. To this end, we developed a method for analyzing and visualizing these changes for the entire brain morphology distribution in the general aging population. The method is applied to 1000 subjects from a large population imaging study in the elderly, from which 900 were used to train the model and 100 were used for testing. The results of the 100 test subjects show that the model generalizes to subjects outside the model population. Smooth percentile curves showing the brain morphology changes as a function of age and spatiotemporal atlases derived from the model population are publicly available via an interactive web application at agingbrain.bigr.nl.

  9. On species sampling sequences induced by residual allocation models

    PubMed Central

    Rodríguez, Abel; Quintana, Fernando A.

    2014-01-01

    We discuss fully Bayesian inference in a class of species sampling models that are induced by residual allocation (sometimes called stick-breaking) priors on almost surely discrete random measures. This class provides a generalization of the well-known Ewens sampling formula that allows for additional flexibility while retaining computational tractability. In particular, the procedure is used to derive the exchangeable predictive probability functions associated with the generalized Dirichlet process of Hjort (2000) and the probit stick-breaking prior of Chung and Dunson (2009) and Rodriguez and Dunson (2011). The procedure is illustrated with applications to genetics and nonparametric mixture modeling. PMID:25477705

  10. Argon-40/Argon-39 Age Spectra of Apollo 17 Highlands Breccia Samples by Laser Step Heating and the Age of the Serenitatis Basin

    NASA Technical Reports Server (NTRS)

    Dalrymple, G. Brent; Ryder, Graham

    1996-01-01

    We have obtained high-resolution (21-63 steps) Ar-40/Ar-39 age spectra using a continuous laser system on 19 submilligram samples of melt rocks and clasts from Apollo 17 samples collected from the pre-Imbrian highlands in the easternmost part of the Serenitatis basin. The samples include poikilitic melt rocks inferred to have been formed in the Serenitatis basin-forming impact, aphanitic melt rock whose compositions vary and whose provenance is uncertain, and granulite, gabbro, and melt clasts. Three of the poikilitic melts have similar age spectrum plateau ages (72395,96, 3893 +/- 16 Ma (2sigma); 72535,7, 3887 +/- 16 Ma; 76315,150, 3900 +/- 16 Ma) with a weighted mean age of 3893 +/- 9 Ma, which we interpret as the best age for the Serenitatis basin- forming impact. Published Ar-40/Ar-39 age spectrum ages of Apollo 17 poikilitic melts are consistent with our new age but are much less precise. Two poikilitic melts did not give plateaus and the maxima in their age spectra indicate ages of greater than or equal to 3869 Ma (72558,7) and greater than or equal to 3743 Ma (77135,178). Plateau ages of two poikilitic melts and two gabbro clasts from 73155 range from 3854 +/- 16 Ma to 3937 +/- 16 Ma and have probably been affected by the ubiquitous (older?) clasts and by post- formation heating (impact) events. Plateau ages from two of the aphanitic melt 'blobs' and two granulites in sample 72255 fall in the narrow range of 3850 q 16 Ma to 3869 q 16 Ma with a weighted mean of 3862 +/- 8 Ma. Two of the aphanitic melt blobs from 72255 have ages of 3883 +/- 16 Ma and greater than or equal to 3894 Ma, whereas a poikilitic melt clast (of different composition from the 'Serenitatis' melts) has an age of 3835 +/- 16 Ma, which is the upper limit for the accretion of 72255. These data suggest that either the aphanitic melts vary in age, as is also suggested by their varying chemical compositions, or they formed in the 72255 accretionary event about 3.84-3.85 Ga and older relict

  11. Age-at-death estimation by pulp/tooth area ratio in canines: study of a 20th-century Mexican sample of prisoners to test Cameriere's method.

    PubMed

    De Luca, Stefano; Bautista, Josefina; Alemán, Inmaculada; Cameriere, Roberto

    2011-09-01

    Accurate age estimation has always been a problem for forensic scientists, and apposition of secondary dentine is often used as an indicator of age. Cameriere et al. studied the pulp/tooth area ratio by peri-apical X-ray images of the canines, to observe the apposition of secondary dentine. The present study examines the application of this technique in a Mexican identified sample coming from the Department of Physical Anthropology of the INAH, at Mexico City. The main aim of this work is to test the reliability of this method in a skeletal sample of a specific population, different from the samples used for its development. The obtained regression model explained 96.2% of total variance (R(2) = 0.962) with a standard error of estimate of 1.909 and a standard deviation of 1.947. These results demonstrate great reliability and that the age/secondary dentine relationship is not variable in this specific population.

  12. Econometric model for age- and population-dependent radiation exposures

    SciTech Connect

    Sandquist, G.M.; Slaughter, D.M. ); Rogers, V.C.

    1991-01-01

    The economic impact associated with ionizing radiation exposures in a given human population depends on numerous factors including the individual's mean economic status as a function age, the age distribution of the population, the future life expectancy at each age, and the latency period for the occurrence of radiation-induced health effects. A simple mathematical model has been developed that provides an analytical methodology for estimating the societal econometrics associated with radiation effects are to be assessed and compared for economic evaluation.

  13. Abstract: Sample Size Planning for Latent Curve Models.

    PubMed

    Lai, Keke

    2011-11-30

    When designing a study that uses structural equation modeling (SEM), an important task is to decide an appropriate sample size. Historically, this task is approached from the power analytic perspective, where the goal is to obtain sufficient power to reject a false null hypothesis. However, hypothesis testing only tells if a population effect is zero and fails to address the question about the population effect size. Moreover, significance tests in the SEM context often reject the null hypothesis too easily, and therefore the problem in practice is having too much power instead of not enough power. An alternative means to infer the population effect is forming confidence intervals (CIs). A CI is more informative than hypothesis testing because a CI provides a range of plausible values for the population effect size of interest. Given the close relationship between CI and sample size, the sample size for an SEM study can be planned with the goal to obtain sufficiently narrow CIs for the population model parameters of interest. Latent curve models (LCMs) is an application of SEM with mean structure to studying change over time. The sample size planning method for LCM from the CI perspective is based on maximum likelihood and expected information matrix. Given a sample, to form a CI for the model parameter of interest in LCM, it requires the sample covariance matrix S, sample mean vector [Formula: see text], and sample size N. Therefore, the width (w) of the resulting CI can be considered a function of S, [Formula: see text], and N. Inverting the CI formation process gives the sample size planning process. The inverted process requires a proxy for the population covariance matrix Σ, population mean vector μ, and the desired width ω as input, and it returns N as output. The specification of the input information for sample size planning needs to be performed based on a systematic literature review. In the context of covariance structure analysis, Lai and Kelley

  14. Multiscale Concrete Modeling of Aging Degradation

    SciTech Connect

    Hammi, Yousseff; Gullett, Philipp; Horstemeyer, Mark F.

    2015-07-31

    In this work a numerical finite element framework is implemented to enable the integration of coupled multiscale and multiphysics transport processes. A User Element subroutine (UEL) in Abaqus is used to simultaneously solve stress equilibrium, heat conduction, and multiple diffusion equations for 2D and 3D linear and quadratic elements. Transport processes in concrete structures and their degradation mechanisms are presented along with the discretization of the governing equations. The multiphysics modeling framework is theoretically extended to the linear elastic fracture mechanics (LEFM) by introducing the eXtended Finite Element Method (XFEM) and based on the XFEM user element implementation of Giner et al. [2009]. A damage model that takes into account the damage contribution from the different degradation mechanisms is theoretically developed. The total contribution of damage is forwarded to a Multi-Stage Fatigue (MSF) model to enable the assessment of the fatigue life and the deterioration of reinforced concrete structures in a nuclear power plant. Finally, two examples are presented to illustrate the developed multiphysics user element implementation and the XFEM implementation of Giner et al. [2009].

  15. Housekeeping Genes and Death Genes in the Penna Aging Model

    NASA Astrophysics Data System (ADS)

    Niewczas, E.; Kurdziel, A.; Cebrat, S.

    The Penna model of aging predicts the accumulation of defective genes expressed after the organism reaches the minimum reproduction age in the genetic pool of the population. The accumulation of defects in the genomes implicates the specific age structure of the modeled populations. Nevertheless, the fraction of defective alleles at loci switched on before the reproduction period does not depend on exact age when precisely they are switched on, it may be just after conception or after birth. We have modeled the mortality of a population in the period before the minimum reproduction age, even before birth, assuming that sets of genes of different size are switched on in different periods of the life span.

  16. Selection Experiments in the Penna Model for Biological Aging

    NASA Astrophysics Data System (ADS)

    Medeiros, G.; Idiart, M. A.; de Almeida, R. M. C.

    We consider the Penna model for biological aging to investigate correlations between early fertility and late life survival rates in populations at equilibrium. We consider inherited initial reproduction ages together with a reproduction cost translated in a probability that mother and offspring die at birth, depending on the mother age. For convenient sets of parameters, the equilibrated populations present genetic variability in what regards both genetically programmed death age and initial reproduction age. In the asexual Penna model, a negative correlation between early life fertility and late life survival rates naturally emerges in the stationary solutions. In the sexual Penna model, selection experiments are performed where individuals are sorted by initial reproduction age from the equilibrated populations and the separated populations are evolved independently. After a transient, a negative correlation between early fertility and late age survival rates also emerges in the sense that populations that start reproducing earlier present smaller average genetically programmed death age. These effects appear due to the age structure of populations in the steady state solution of the evolution equations. We claim that the same demographic effects may be playing an important role in selection experiments in the laboratory.

  17. Modeling 3D faces from samplings via compressive sensing

    NASA Astrophysics Data System (ADS)

    Sun, Qi; Tang, Yanlong; Hu, Ping

    2013-07-01

    3D data is easier to acquire for family entertainment purpose today because of the mass-production, cheapness and portability of domestic RGBD sensors, e.g., Microsoft Kinect. However, the accuracy of facial modeling is affected by the roughness and instability of the raw input data from such sensors. To overcome this problem, we introduce compressive sensing (CS) method to build a novel 3D super-resolution scheme to reconstruct high-resolution facial models from rough samples captured by Kinect. Unlike the simple frame fusion super-resolution method, this approach aims to acquire compressed samples for storage before a high-resolution image is produced. In this scheme, depth frames are firstly captured and then each of them is measured into compressed samples using sparse coding. Next, the samples are fused to produce an optimal one and finally a high-resolution image is recovered from the fused sample. This framework is able to recover 3D facial model of a given user from compressed simples and this can reducing storage space as well as measurement cost in future devices e.g., single-pixel depth cameras. Hence, this work can potentially be applied into future applications, such as access control system using face recognition, and smart phones with depth cameras, which need high resolution and little measure time.

  18. Modeling Background Attenuation by Sample Matrix in Gamma Spectrometric Analyses

    SciTech Connect

    Bastos, Rodrigo O.; Appoloni, Carlos R.

    2008-08-07

    In laboratory gamma spectrometric analyses, the procedures for estimating background usually overestimate it. If an empty container similar to that used to hold samples is measured, it does not consider the background attenuation by sample matrix. If a 'blank' sample is measured, the hypothesis that this sample will be free of radionuclides is generally not true. The activity of this 'blank' sample is frequently sufficient to mask or to overwhelm the effect of attenuation so that the background remains overestimated. In order to overcome this problem, a model was developed to obtain the attenuated background from the spectrum acquired with the empty container. Beyond reasonable hypotheses, the model presumes the knowledge of the linear attenuation coefficient of the samples and its dependence on photon energy and samples densities. An evaluation of the effects of this model on the Lowest Limit of Detection (LLD) is presented for geological samples placed in cylindrical containers that completely cover the top of an HPGe detector that has a 66% relative efficiency. The results are presented for energies in the range of 63 to 2614keV, for sample densities varying from 1.5 to 2.5 g{center_dot}cm{sup -3}, and for the height of the material on the detector of 2 cm and 5 cm. For a sample density of 2.0 g{center_dot}cm{sup -3} and with a 2cm height, the method allowed for a lowering of 3.4% of the LLD for the energy of 1460keV, from {sup 40}K, 3.9% for the energy of 911keV from {sup 228}Ac, 4.5% for the energy of 609keV from {sup 214}Bi, and8.3% for the energy of 92keV from {sup 234}Th. For a sample density of 1.75 g{center_dot}cm{sup -3} and a 5cm height, the method indicates a lowering of 6.5%, 7.4%, 8.3% and 12.9% of the LLD for the same respective energies.

  19. Radiocarbon age modeling: dissolution, bioturbation and sediment redistribution

    NASA Astrophysics Data System (ADS)

    Mekik, F.

    2012-12-01

    We generated radiocarbon dates for whole and fragmented planktonic foraminifer tests (by several species) from a series of core tops which have experienced little dissolution from two depth transects (Rio Grande Rise - RIO and Ontong Java Plateau - OJP) and from down core records from three tropical Pacific cores with significantly different sediment accumulation rates. We also generated new radiocarbon data from both whole Globorotalia menardii shells and its fragments within the same sediments in order to test the robustness of a calcite dissolution proxy, the G. menardii Fragmentation Index (MFI). Our data reveal that the ages of all sediment components increase with increasing dissolution. This is most easily observable on RIO where the age offset between the shallowest samples and deepest samples is ~5 ka, while the mixing ages of the cores are ~1.9ka. This result is new and significant because previous work has always been in the tropical Pacific where bioturbation and mixing ages are high. Furthermore, two of the 7 core top samples from RIO revealed whole G. menardii shells of Glacial age. This is surprising because G. menardiis have not been reported in sediments from the Atlantic Ocean older than 13,000 years. Lastly, we found that the higher the sediment accumulation rate, the closer the age offset between G. menradii whole shells and its fragments in the same sediments both on RIO and OJP. This is important for the interpretation of down core work with MFI.

  20. Travelling Wave Solutions in Multigroup Age-Structured Epidemic Models

    NASA Astrophysics Data System (ADS)

    Ducrot, Arnaut; Magal, Pierre; Ruan, Shigui

    2010-01-01

    Age-structured epidemic models have been used to describe either the age of individuals or the age of infection of certain diseases and to determine how these characteristics affect the outcomes and consequences of epidemiological processes. Most results on age-structured epidemic models focus on the existence, uniqueness, and convergence to disease equilibria of solutions. In this paper we investigate the existence of travelling wave solutions in a deterministic age-structured model describing the circulation of a disease within a population of multigroups. Individuals of each group are able to move with a random walk which is modelled by the classical Fickian diffusion and are classified into two subclasses, susceptible and infective. A susceptible individual in a given group can be crisscross infected by direct contact with infective individuals of possibly any group. This process of transmission can depend upon the age of the disease of infected individuals. The goal of this paper is to provide sufficient conditions that ensure the existence of travelling wave solutions for the age-structured epidemic model. The case of two population groups is numerically investigated which applies to the crisscross transmission of feline immunodeficiency virus (FIV) and some sexual transmission diseases.

  1. A three stage sampling model for remote sensing applications

    NASA Technical Reports Server (NTRS)

    Eisgruber, L. M.

    1972-01-01

    A conceptual model and an empirical application of the relationship between the manner of selecting observations and its effect on the precision of estimates from remote sensing are reported. This three stage sampling scheme considers flightlines, segments within flightlines, and units within these segments. The error of estimate is dependent on the number of observations in each of the stages.

  2. Automated biowaste sampling system urine subsystem operating model, part 1

    NASA Technical Reports Server (NTRS)

    Fogal, G. L.; Mangialardi, J. K.; Rosen, F.

    1973-01-01

    The urine subsystem automatically provides for the collection, volume sensing, and sampling of urine from six subjects during space flight. Verification of the subsystem design was a primary objective of the current effort which was accomplished thru the detail design, fabrication, and verification testing of an operating model of the subsystem.

  3. Language Arts Curriculum Framework: Sample Curriculum Model, Grade 8.

    ERIC Educational Resources Information Center

    Arkansas State Dept. of Education, Little Rock.

    Based on the 1998 Arkansas English Language Arts Curriculum Frameworks, this sample curriculum model for grade eight language arts is divided into sections focusing on writing; reading; and listening, speaking, and viewing. The writing section's stated goals are to help students employ a wide range of strategies as they write; use different…

  4. Language Arts Curriculum Framework: Sample Curriculum Model, Grade 5.

    ERIC Educational Resources Information Center

    Arkansas State Dept. of Education, Little Rock.

    Based on the 1998 Arkansas English Language Arts Curriculum Frameworks, this sample curriculum model for grade five language arts is divided into sections focusing on writing; reading; and listening, speaking, and viewing. The writing section's stated goals are to help students employ a wide range of strategies as they write; use different writing…

  5. Language Arts Curriculum Framework: Sample Curriculum Model, Grade 7.

    ERIC Educational Resources Information Center

    Arkansas State Dept. of Education, Little Rock.

    Based on the 1998 Arkansas English Language Arts Curriculum Frameworks, this sample curriculum model for grade seven language arts is divided into sections focusing on writing; reading; and listening, speaking, and viewing. The writing section's stated goals are to help students employ a wide range of strategies as they write; use different…

  6. Language Arts Curriculum Framework: Sample Curriculum Model, Grade 6.

    ERIC Educational Resources Information Center

    Arkansas State Dept. of Education, Little Rock.

    Based on the 1998 Arkansas English Language Arts Curriculum Frameworks, this sample curriculum model for grade six language arts is divided into sections focusing on writing; reading; and listening, speaking, and viewing. The writing section's stated goals are to help students employ a wide range of strategies as they write; use different writing…

  7. Aging mechanism in model Pickering emulsion

    NASA Astrophysics Data System (ADS)

    Fouilloux, Sarah; Malloggi, Florent; Daillant, Jean; Thill, Antoine

    We study the stability of a model Pickering emulsion system. A special counter-flow microfluidics set-up was used to prepare monodisperse Pickering emulsions, with oil droplets in water. The wettability of the monodisperse silica nanoparticles (NPs) could be tuned by surface grafting and the surface coverage of the droplets was controlled using the microfluidics setup. A surface coverage as low as 23$\\%$ is enough to stabilize the emulsions and we evidence a new regime of Pickering emulsion stability where the surface coverage of emulsion droplets of constant size increases in time, in coexistence with a large amount of dispersed phase. Our results demonstrate that the previously observed limited coalescence regime where surface coverage tends to control the average size of the final droplets must be put in a broader perspective.

  8. USING A COMMERCIAL TELEPHONE DIRECTORY TO IDENTIFY A POPULATION-BASED SAMPLE OF WOMEN OF REPRODUCTIVE AGE

    EPA Science Inventory

    Using a commercial telephone directory to identify a population-based sample of women of reproductive age
    *DT Lobdell, GM Buck, JM Weiner, P Mendola (United States Environmental Protection Agency, Research Triangle Park, NC 27711)

    In the United States, sampling women o...

  9. Comparison of DSM-IV Symptoms in Elementary School-Age Children with PDD versus Clinic and Community Samples

    ERIC Educational Resources Information Center

    Gadow, Kenneth D.; Devincent, Carla J.; Pomeroy, John; Azizian, Allen

    2005-01-01

    This study compares DSM-IV symptoms in children (ages 6 to 12 years) with pervasive developmental disorder (PDD), clinic controls, and community-based samples. Parents/teachers completed the Child Symptom Inventory-4 for four samples: PDD (N= 284/284) and non-PDD psychiatric clinic referrals (N= 189/181) and pupils in regular (N= 385/404) and…

  10. Development of a bioenergetics model for age-0 American Shad

    USGS Publications Warehouse

    Sauter, Sally T.

    2011-01-01

    Bioenergetics modeling can be used as a tool to investigate the impact of non-native age-0 American shad (Alosa sapidissima) on reservoir and estuary food webs. The model can increase our understanding of how these fish influence lower trophic levels as well as predatory fish populations that feed on juvenile salmonids. Bioenergetics modeling can be used to investigate ecological processes, evaluate alternative research hypotheses, provide decision support, and quantitative prediction. Bioenergetics modeling has proven to be extremely useful in fisheries research (Ney et al. 1993,Chips and Wahl 2008, Petersen et al. 2008). If growth and diet parameters are known, the bioenergetics model can be used to quantify the relative amount of zooplankton or insects consumed by age-0 American shad. When linked with spatial and temporal information on fish abundance, model output can guide inferential hypothesis development to demonstrate where the greatest impacts of age-0 American shad might occur.

  11. The Healthy Aging Research Network: Modeling Collaboration for Community Impact.

    PubMed

    Belza, Basia; Altpeter, Mary; Smith, Matthew Lee; Ory, Marcia G

    2017-03-01

    As the first Centers for Disease Control and Prevention (CDC) Prevention Research Centers Program thematic network, the Healthy Aging Research Network was established to better understand the determinants of healthy aging within older adult populations, identify interventions that promote healthy aging, and assist in translating research into sustainable community-based programs throughout the nation. To achieve these goals requires concerted efforts of a collaborative network of academic, community, and public health organizational partnerships. For the 2001-2014 Prevention Research Center funding cycles, the Healthy Aging Research Network conducted prevention research and promoted the wide use of practices known to foster optimal health. Organized around components necessary for successful collaborations (i.e., governance and infrastructure, shaping focus, community involvement, and evaluation and improvement), this commentary highlights exemplars that demonstrate the Healthy Aging Research Network's unique contributions to the field. The Healthy Aging Research Network's collaboration provided a means to collectively build capacity for practice and policy, reduce fragmentation and duplication in health promotion and aging research efforts, maximize the efficient use of existing resources and generate additional resources, and ultimately, create synergies for advancing the healthy aging agenda. This collaborative model was built upon a backbone organization (coordinating center); setting of common agendas and mutually reinforcing activities; and continuous communications. Given its successes, the Healthy Aging Research Network model could be used to create new and evaluate existing thematic networks to guide the translation of research into policy and practice.

  12. Ageing and bilingualism: absence of a "bilingual advantage" in stroop interference in a nonimmigrant sample.

    PubMed

    Kousaie, Shanna; Phillips, Natalie A

    2012-01-01

    Previous research has found an advantage for bilinguals relative to monolinguals on tasks of attentional control. This advantage has been found to be larger in older adults than in young adults, suggesting that bilingualism provides a buffer against age-related declines in executive functioning. Using a computerized Stroop task in a nonimmigrant sample of young and older monolinguals and bilinguals, the current investigation tried to replicate previous findings of a bilingual advantage. A bilingual advantage would have been demonstrated by smaller Stroop interference (i.e., smaller increases in response time for incongruent than for neutral trials) for bilinguals than for monolinguals. The results showed that bilingual young adults showed a general speed advantage relative to their monolingual counterparts, but this was not associated with smaller Stroop interference. Older adults showed no effect of bilingualism. Thus, the present investigation does not find evidence of a bilingual advantage in young or older adults and suggests limits to the robustness and/or specificity of previous findings.

  13. Language, reading, and math learning profiles in an epidemiological sample of school age children.

    PubMed

    Archibald, Lisa M D; Oram Cardy, Janis; Joanisse, Marc F; Ansari, Daniel

    2013-01-01

    Dyscalculia, dyslexia, and specific language impairment (SLI) are relatively specific developmental learning disabilities in math, reading, and oral language, respectively, that occur in the context of average intellectual capacity and adequate environmental opportunities. Past research has been dominated by studies focused on single impairments despite the widespread recognition that overlapping and comorbid deficits are common. The present study took an epidemiological approach to study the learning profiles of a large school age sample in language, reading, and math. Both general learning profiles reflecting good or poor performance across measures and specific learning profiles involving either weak language, weak reading, weak math, or weak math and reading were observed. These latter four profiles characterized 70% of children with some evidence of a learning disability. Low scores in phonological short-term memory characterized clusters with a language-based weakness whereas low or variable phonological awareness was associated with the reading (but not language-based) weaknesses. The low math only group did not show these phonological deficits. These findings may suggest different etiologies for language-based deficits in language, reading, and math, reading-related impairments in reading and math, and isolated math disabilities.

  14. Sequential Sampling Models in Cognitive Neuroscience: Advantages, Applications, and Extensions

    PubMed Central

    Forstmann, B.U.; Ratcliff, R.; Wagenmakers, E.-J.

    2016-01-01

    Sequential sampling models assume that people make speeded decisions by gradually accumulating noisy information until a threshold of evidence is reached. In cognitive science, one such model—the diffusion decision model—is now regularly used to decompose task performance into underlying processes such as the quality of information processing, response caution, and a priori bias. In the cognitive neurosciences, the diffusion decision model has recently been adopted as a quantitative tool to study the neural basis of decision making under time pressure. We present a selective overview of several recent applications and extensions of the diffusion decision model in the cognitive neurosciences. PMID:26393872

  15. Age-related bone loss in the LOU/c rat model of healthy ageing.

    PubMed

    Duque, Gustavo; Rivas, Daniel; Li, Wei; Li, Ailian; Henderson, Janet E; Ferland, Guylaine; Gaudreau, Pierrette

    2009-03-01

    Inbred albino Louvain (LOU) rats are considered a model of healthy aging due to their increased longevity in the absence of obesity and with a low incidence of common age-related diseases. In this study, we characterized the bone phenotype of male and female LOU rats at 4, 20 and 27 months of age using quantitative micro computed tomographic (mCT) imaging, histology and biochemical analysis of circulating bone biomarkers. Bone quality and morphometry of the distal femora, assessed by mCT, was similar in male and female rats at 4 months of age and deteriorated over time. Histochemical staining of undecalcified bone showed a significant reduction in cortical and trabecular bone by 20 months of age. The reduction in mineralized tissue was accompanied by reduced numbers of osteoblasts and osteoclasts and a significant increase in marrow adiposity. Biochemical markers of bone turnover, C-telopeptide and osteocalcin, correlated with the age-related bone loss whereas the calciotropic hormones PTH and vitamin D remained unchanged over time. In summary, aged LOU rats exhibit low-turnover bone loss and marrow fat infiltration, which are the hallmarks of senile osteoporosis, and thus represent a novel model in which to study the molecular mechanisms leading to this disorder.

  16. Data augmentation for models based on rejection sampling

    PubMed Central

    Rao, Vinayak; Lin, Lizhen; Dunson, David B.

    2016-01-01

    We present a data augmentation scheme to perform Markov chain Monte Carlo inference for models where data generation involves a rejection sampling algorithm. Our idea is a simple scheme to instantiate the rejected proposals preceding each data point. The resulting joint probability over observed and rejected variables can be much simpler than the marginal distribution over the observed variables, which often involves intractable integrals. We consider three problems: modelling flow-cytometry measurements subject to truncation; the Bayesian analysis of the matrix Langevin distribution on the Stiefel manifold; and Bayesian inference for a nonparametric Gaussian process density model. The latter two are instances of doubly-intractable Markov chain Monte Carlo problems, where evaluating the likelihood is intractable. Our experiments demonstrate superior performance over state-of-the-art sampling algorithms for such problems. PMID:27279660

  17. Exact solution of an evolutionary model without aging.

    PubMed

    Onody, R N; de Medeiros, N G

    1999-09-01

    We introduce an age-structured asexual population model containing all the relevant features of evolutionary aging theories. Beneficial as well as deleterious mutations, heredity, and arbitrary fecundity are present and managed by natural selection. An exact solution without aging is found. We show that fertility is associated with generalized forms of the Fibonacci sequence, while mutations and natural selection are merged into an integral equation which is solved by Fourier series. Average survival probabilities and Malthusian growth exponents are calculated and indicate that the system may exhibit mutational meltdown. The relevance of the model in the context of fissile reproduction groups like many protozoa and coelenterates is discussed.

  18. Exact solution of an evolutionary model without aging

    NASA Astrophysics Data System (ADS)

    Onody, Roberto N.; de Medeiros, Nazareno G. F.

    1999-09-01

    We introduce an age-structured asexual population model containing all the relevant features of evolutionary aging theories. Beneficial as well as deleterious mutations, heredity, and arbitrary fecundity are present and managed by natural selection. An exact solution without aging is found. We show that fertility is associated with generalized forms of the Fibonacci sequence, while mutations and natural selection are merged into an integral equation which is solved by Fourier series. Average survival probabilities and Malthusian growth exponents are calculated and indicate that the system may exhibit mutational meltdown. The relevance of the model in the context of fissile reproduction groups like many protozoa and coelenterates is discussed.

  19. The development of small primate models for aging research.

    PubMed

    Fischer, Kathleen E; Austad, Steven N

    2011-01-01

    Nonhuman primate (NHP) aging research has traditionally relied mainly on the rhesus macaque. But the long lifespan, low reproductive rate, and relatively large body size of macaques and related Old World monkeys make them less than ideal models for aging research. Manifold advantages would attend the use of smaller, more rapidly developing, shorter-lived NHP species in aging studies, not the least of which are lower cost and the ability to do shorter research projects. Arbitrarily defining "small" primates as those weighing less than 500 g, we assess small, relatively short-lived species among the prosimians and callitrichids for suitability as models for human aging research. Using the criteria of availability, knowledge about (and ease of) maintenance, the possibility of genetic manipulation (a hallmark of 21st century biology), and similarities to humans in the physiology of age-related changes, we suggest three species--two prosimians (Microcebus murinus and Galago senegalensis) and one New World monkey (Callithrix jacchus)--that deserve scrutiny for development as major NHP models for aging studies. We discuss one other New World monkey group, Cebus spp., that might also be an effective NHP model of aging as these species are longer-lived for their body size than any primate except humans.

  20. Tigers on trails: occupancy modeling for cluster sampling.

    PubMed

    Hines, J E; Nichols, J D; Royle, J A; MacKenzie, D I; Gopalaswamy, A M; Kumar, N Samba; Karanth, K U

    2010-07-01

    Occupancy modeling focuses on inference about the distribution of organisms over space, using temporal or spatial replication to allow inference about the detection process. Inference based on spatial replication strictly requires that replicates be selected randomly and with replacement, but the importance of these design requirements is not well understood. This paper focuses on an increasingly popular sampling design based on spatial replicates that are not selected randomly and that are expected to exhibit Markovian dependence. We develop two new occupancy models for data collected under this sort of design, one based on an underlying Markov model for spatial dependence and the other based on a trap response model with Markovian detections. We then simulated data under the model for Markovian spatial dependence and fit the data to standard occupancy models and to the two new models. Bias of occupancy estimates was substantial for the standard models, smaller for the new trap response model, and negligible for the new spatial process model. We also fit these models to data from a large-scale tiger occupancy survey recently conducted in Karnataka State, southwestern India. In addition to providing evidence of a positive relationship between tiger occupancy and habitat, model selection statistics and estimates strongly supported the use of the model with Markovian spatial dependence. This new model provides another tool for the decomposition of the detection process, which is sometimes needed for proper estimation and which may also permit interesting biological inferences. In addition to designs employing spatial replication, we note the likely existence of temporal Markovian dependence in many designs using temporal replication. The models developed here will be useful either directly, or with minor extensions, for these designs as well. We believe that these new models represent important additions to the suite of modeling tools now available for occupancy

  1. The heuristic value of redundancy models of aging.

    PubMed

    Boonekamp, Jelle J; Briga, Michael; Verhulst, Simon

    2015-11-01

    Molecular studies of aging aim to unravel the cause(s) of aging bottom-up, but linking these mechanisms to organismal level processes remains a challenge. We propose that complementary top-down data-directed modelling of organismal level empirical findings may contribute to developing these links. To this end, we explore the heuristic value of redundancy models of aging to develop a deeper insight into the mechanisms causing variation in senescence and lifespan. We start by showing (i) how different redundancy model parameters affect projected aging and mortality, and (ii) how variation in redundancy model parameters relates to variation in parameters of the Gompertz equation. Lifestyle changes or medical interventions during life can modify mortality rate, and we investigate (iii) how interventions that change specific redundancy parameters within the model affect subsequent mortality and actuarial senescence. Lastly, as an example of data-directed modelling and the insights that can be gained from this, (iv) we fit a redundancy model to mortality patterns observed by Mair et al. (2003; Science 301: 1731-1733) in Drosophila that were subjected to dietary restriction and temperature manipulations. Mair et al. found that dietary restriction instantaneously reduced mortality rate without affecting aging, while temperature manipulations had more transient effects on mortality rate and did affect aging. We show that after adjusting model parameters the redundancy model describes both effects well, and a comparison of the parameter values yields a deeper insight in the mechanisms causing these contrasting effects. We see replacement of the redundancy model parameters by more detailed sub-models of these parameters as a next step in linking demographic patterns to underlying molecular mechanisms.

  2. Modeling Age-Friendly Environment, Active Aging, and Social Connectedness in an Emerging Asian Economy.

    PubMed

    Lai, Ming-Ming; Lein, Shi-Ying; Lau, Siok-Hwa; Lai, Ming-Ling

    2016-01-01

    This paper empirically tested eight key features of WHO guidelines to age-friendly community by surveying 211 informal caregivers and 402 self-care adults (aged 45 to 85 and above) in Malaysia. We examined the associations of these eight features with active aging and social connectedness through exploratory and confirmatory factor analyses. A structural model with satisfactory goodness-of-fit indices (CMIN/df = 1.11, RMSEA = 0.02, NFI = 0.97, TLI = 1.00, CFI = 1.00, and GFI = 0.96) indicates that transportation and housing, community support and health services, and outdoor spaces and buildings are statistically significant in creating an age-friendly environment. We found a statistically significant positive relationship between an age-friendly environment and active aging. This relationship is mediated by social connectedness. The results indicate that built environments such as accessible public transportations and housing, affordable and accessible healthcare services, and elderly friendly outdoor spaces and buildings have to be put into place before social environment in building an age-friendly environment. Otherwise, the structural barriers would hinder social interactions for the aged. The removal of the environmental barriers and improved public transportation services provide short-term solutions to meet the varied and growing needs of the older population.

  3. Modeling Age-Friendly Environment, Active Aging, and Social Connectedness in an Emerging Asian Economy

    PubMed Central

    Lai, Ming-Ming; Lein, Shi-Ying; Lau, Siok-Hwa; Lai, Ming-Ling

    2016-01-01

    This paper empirically tested eight key features of WHO guidelines to age-friendly community by surveying 211 informal caregivers and 402 self-care adults (aged 45 to 85 and above) in Malaysia. We examined the associations of these eight features with active aging and social connectedness through exploratory and confirmatory factor analyses. A structural model with satisfactory goodness-of-fit indices (CMIN/df = 1.11, RMSEA = 0.02, NFI = 0.97, TLI = 1.00, CFI = 1.00, and GFI = 0.96) indicates that transportation and housing, community support and health services, and outdoor spaces and buildings are statistically significant in creating an age-friendly environment. We found a statistically significant positive relationship between an age-friendly environment and active aging. This relationship is mediated by social connectedness. The results indicate that built environments such as accessible public transportations and housing, affordable and accessible healthcare services, and elderly friendly outdoor spaces and buildings have to be put into place before social environment in building an age-friendly environment. Otherwise, the structural barriers would hinder social interactions for the aged. The removal of the environmental barriers and improved public transportation services provide short-term solutions to meet the varied and growing needs of the older population. PMID:27293889

  4. Evidence that a single gene with gender- and age-dependent effects influences systolic blood pressure determination in a population-based sample.

    PubMed Central

    Pérusse, L; Moll, P P; Sing, C F

    1991-01-01

    A biometrical study was carried out to evaluate the role of genetic variation in determining interindividual differences in systolic blood pressure (SBP) in the population at large. SBP was measured in 1,266 Caucasian individuals in 278 pedigrees ascertained through children enrolled in the Rochester, MN, school system. The sample included 646 males and 620 females 550 years of age and not taking antihypertensive medication or oral contraceptives. Complex segregation analysis was first applied to these data by using a regression model for age, in which the intercept was gender and ousiotype specific but in which the slope was only gender specific. When the slope was independent of ousiotype, neither variation at a single gene combined with polygenic effects (mixed genetic model) nor variation in a single environmental factor combined with polygenetic effects (mixed environmental model) explained the distribution of SBP in this sample. However, when the regression model for age allowed both the intercept and slope to be gender and ousiotype specific, the mixed environmental model was rejected whereas the mixed genetic model was not. These results suggest that variability in SBP may be influenced by major effects of allelic variation at a single gene that are both gender and age dependent. This study (1) suggests that particular genotypes determined by a single gene are associated with a steeper increase of SBP with age among males and females 550 years of age in the general population and (2) illustrates the need to consider models that more realistically represent the relationship between genotypic variability and phenotypic variability, to understand the genetics of human quantitative traits. PMID:2063879

  5. The evaluation of age-related histomorphometric variables in a cadaver sample of lower socioeconomic status: implications for estimating age at death.

    PubMed

    Keough, N; L'Abbé, E N; Steyn, M

    2009-10-30

    Estimating age at death from adult skeletal remains is a daunting task for human osteologists. For this reason, the evaluation of micro-structural changes in bone with advancing age has become a popular method. However, factors such as nutrition, chronic disease, population group and sex have been suggested to influence the rate of bone turnover, and thus the use of histological methods in providing an accurate age at death has been questioned. The purpose of this study was to evaluate the accuracy and repeatability of 10 histomorphometric traits used to estimate age. The sample comprised of 146 dissection room cadavers of known sex, age and ancestry (105 males and 41 females). A 0.2cmx1.0cm sample was removed from the anterior surface of the mid-shaft of the femur (opposite the linea aspera), and slides were prepared according to standard methodology. The total osteon count (r=0.50), the percentage unremodelled bone (r=-0.50), the total number of non-Haversian canals (r=-0.50) and the average percentage of fragmental bone (r=0.55) had moderate correlations with age, while the total number of measurable osteons (r=0.43), the total number of osteonal fragments (r=0.40), the percentage of fragmentary bone (r=0.37) the average number of lamellae per osteon (r=0.29), the minimum diameter of the Haversian canals (r=0.14) and resorption spaces (r=0.11) had little to no relationship with age. Despite poor correlations with age, eight variables were shown to be highly repeatable (r=0.74-0.93). Moderate to low correlations with age may be attributed to these variables not being related to age in a progressive and predictable fashion, activity patterns or possible chronic disease in the sample. A databank needs to be compiled from larger samples from various populations in order to more holistically assess the relationship between these variables and age as well as other mitigating factors such as disease, nutrition and population group.

  6. De novo protein conformational sampling using a probabilistic graphical model.

    PubMed

    Bhattacharya, Debswapna; Cheng, Jianlin

    2015-11-06

    Efficient exploration of protein conformational space remains challenging especially for large proteins when assembling discretized structural fragments extracted from a protein structure data database. We propose a fragment-free probabilistic graphical model, FUSION, for conformational sampling in continuous space and assess its accuracy using 'blind' protein targets with a length up to 250 residues from the CASP11 structure prediction exercise. The method reduces sampling bottlenecks, exhibits strong convergence, and demonstrates better performance than the popular fragment assembly method, ROSETTA, on relatively larger proteins with a length of more than 150 residues in our benchmark set. FUSION is freely available through a web server at http://protein.rnet.missouri.edu/FUSION/.

  7. Invertebrates as model organisms for research on aging biology

    PubMed Central

    Murthy, Mahadev; Ram, Jeffrey L.

    2015-01-01

    Invertebrate model systems, such as nematodes and fruit flies, have provided valuable information about the genetics and cellular biology involved in aging. However, limitations of these simple, genetically tractable organisms suggest the need for other model systems, some of them invertebrate, to facilitate further advances in the understanding of mechanisms of aging and longevity in mammals, including humans. This paper introduces 10 review articles about the use of invertebrate model systems for the study of aging by authors who participated in an ‘NIA-NIH symposium on aging in invertebrate model systems’ at the 2013 International Congress for Invertebrate Reproduction and Development. In contrast to the highly derived characteristics of nematodes and fruit flies as members of the superphylum Ecdysozoa, cnidarians, such as Hydra, are more ‘basal’ organisms that have a greater number of genetic orthologs in common with humans. Moreover, some other new model systems, such as the urochordate Botryllus schlosseri, the tunicate Ciona, and the sea urchins (Echinodermata) are members of the Deuterostomia, the same superphylum that includes all vertebrates, and thus have mechanisms that are likely to be more closely related to those occurring in humans. Additional characteristics of these new model systems, such as the recent development of new molecular and genetic tools and a more similar pattern to humans of regeneration and stem cell function suggest that these new model systems may have unique advantages for the study of mechanisms of aging and longevity. PMID:26241448

  8. An Age-Graded Model for Career Development Education

    ERIC Educational Resources Information Center

    Tuckman, Bruce W.

    1974-01-01

    This paper attempts to provide a framework by which educators interested in stimulating career development can choose the learning experiences most likely to have payoffs for different age youth. Eight stages of child development are described with career development themes suggested for each stage along with sample activities. (Author)

  9. The genealogy of samples in models with selection.

    PubMed

    Neuhauser, C; Krone, S M

    1997-02-01

    We introduce the genealogy of a random sample of genes taken from a large haploid population that evolves according to random reproduction with selection and mutation. Without selection, the genealogy is described by Kingman's well-known coalescent process. In the selective case, the genealogy of the sample is embedded in a graph with a coalescing and branching structure. We describe this graph, called the ancestral selection graph, and point out differences and similarities with Kingman's coalescent. We present simulations for a two-allele model with symmetric mutation in which one of the alleles has a selective advantage over the other. We find that when the allele frequencies in the population are already in equilibrium, then the genealogy does not differ much from the neutral case. This is supported by rigorous results. Furthermore, we describe the ancestral selection graph for other selective models with finitely many selection classes, such as the K-allele models, infinitely-many-alleles models. DNA sequence models, and infinitely-many-sites models, and briefly discuss the diploid case.

  10. Learning Adaptive Forecasting Models from Irregularly Sampled Multivariate Clinical Data.

    PubMed

    Liu, Zitao; Hauskrecht, Milos

    2016-02-01

    Building accurate predictive models of clinical multivariate time series is crucial for understanding of the patient condition, the dynamics of a disease, and clinical decision making. A challenging aspect of this process is that the model should be flexible and adaptive to reflect well patient-specific temporal behaviors and this also in the case when the available patient-specific data are sparse and short span. To address this problem we propose and develop an adaptive two-stage forecasting approach for modeling multivariate, irregularly sampled clinical time series of varying lengths. The proposed model (1) learns the population trend from a collection of time series for past patients; (2) captures individual-specific short-term multivariate variability; and (3) adapts by automatically adjusting its predictions based on new observations. The proposed forecasting model is evaluated on a real-world clinical time series dataset. The results demonstrate the benefits of our approach on the prediction tasks for multivariate, irregularly sampled clinical time series, and show that it can outperform both the population based and patient-specific time series prediction models in terms of prediction accuracy.

  11. Learning Adaptive Forecasting Models from Irregularly Sampled Multivariate Clinical Data

    PubMed Central

    Liu, Zitao; Hauskrecht, Milos

    2016-01-01

    Building accurate predictive models of clinical multivariate time series is crucial for understanding of the patient condition, the dynamics of a disease, and clinical decision making. A challenging aspect of this process is that the model should be flexible and adaptive to reflect well patient-specific temporal behaviors and this also in the case when the available patient-specific data are sparse and short span. To address this problem we propose and develop an adaptive two-stage forecasting approach for modeling multivariate, irregularly sampled clinical time series of varying lengths. The proposed model (1) learns the population trend from a collection of time series for past patients; (2) captures individual-specific short-term multivariate variability; and (3) adapts by automatically adjusting its predictions based on new observations. The proposed forecasting model is evaluated on a real-world clinical time series dataset. The results demonstrate the benefits of our approach on the prediction tasks for multivariate, irregularly sampled clinical time series, and show that it can outperform both the population based and patient-specific time series prediction models in terms of prediction accuracy. PMID:27525189

  12. The Genealogy of Samples in Models with Selection

    PubMed Central

    Neuhauser, C.; Krone, S. M.

    1997-01-01

    We introduce the genealogy of a random sample of genes taken from a large haploid population that evolves according to random reproduction with selection and mutation. Without selection, the genealogy is described by Kingman's well-known coalescent process. In the selective case, the genealogy of the sample is embedded in a graph with a coalescing and branching structure. We describe this graph, called the ancestral selection graph, and point out differences and similarities with Kingman's coalescent. We present simulations for a two-allele model with symmetric mutation in which one of the alleles has a selective advantage over the other. We find that when the allele frequencies in the population are already in equilibrium, then the genealogy does not differ much from the neutral case. This is supported by rigorous results. Furthermore, we describe the ancestral selection graph for other selective models with finitely many selection classes, such as the K-allele models, infinitely-many-alleles models, DNA sequence models, and infinitely-many-sites models, and briefly discuss the diploid case. PMID:9071604

  13. Age and equity in liver transplantation: An organ allocation model.

    PubMed

    Cucchetti, Alessandro; Ross, Lainie Friedman; Thistlethwaite, J Richard; Vitale, Alessandro; Ravaioli, Matteo; Cescon, Matteo; Ercolani, Giorgio; Burra, Patrizia; Cillo, Umberto; Pinna, Antonio Daniele

    2015-10-01

    A moral liver allocation policy must be fair. We considered a 2-step, 2-principle allocation system called "age mapping." Its first principle, equal opportunity, ensures that candidates of all ages have an equal chance of getting an organ. Its second principle, prudential lifespan equity, allocates younger donor grafts to younger candidates and older donors to older candidates in order to increase the likelihood that all recipients achieve a "full lifespan." Data from 2476 candidates and 1371 consecutive adult liver transplantations (from 1999 to 2012) were used to determine whether age mapping can reduce the gap in years of life lost (YLL) between younger and older recipients. A parametric Weibull prognostic model was developed to estimate total life expectancy after transplantation using survival of the general population matched by sex and age as a reference. Life expectancy from birth was calculated by adding age at transplant and total life expectancy after transplantation. In multivariate analysis, recipient age, hepatitis C virus status, Model for End-Stage Liver Disease score at transplant of >30, and donor age were significantly related to prognosis after surgery (P < 0.05). The mean (and standard deviation) number of years of life from birth, calculated from the current allocation model, for various age groups were: recipients 18-47 years (n = 340) = 65.2 (3.3); 48-55 years (n = 387) = 72.7 (2.1); 56-61 years (n = 372) = 74.7 (1.7) and for recipients >61 years (n = 272) = 77.4 (1.4). The total number of YLL equaled 523 years. Redistributing liver grafts, using an age mapping algorithm, reduces the lifespan gap between younger and older candidates by 33% (from 12.3% to 8.3%) and achieves a 14% overall reduction of YLL (73 years) compared to baseline liver distribution. In conclusion, deliberately incorporating age into an allocation algorithm promotes fairness and increases efficiency.

  14. Aging males' symptoms in relation to the genetically determined androgen receptor CAG polymorphism, sex hormone levels and sample membership.

    PubMed

    Schneider, Gudrun; Nienhaus, Kathrin; Gromoll, Jörg; Heuft, Gereon; Nieschlag, Eberhard; Zitzmann, Michael

    2010-05-01

    Late-onset hypogonadism describes the co-occurrence of a range of physical, psychological and sexual symptoms in aging men, with the implication that these symptoms are caused by androgen deficiency. Previous investigations examined mostly population samples and did not take into account the testosterone modulating effects of the genetically determined CAG repeat polymorphism (CAGn) of the androgen receptor (AR) gene. This is the first study which investigates aging male symptoms (AMS) in relation to the genetically determined androgen receptor CAG polymorphism, estradiol and testosterone levels in men > or =50 years of age in a healthy population sample (n=100), outpatients of an andrological department (n=76) who presented with sexual and "aging male" symptoms and a psychosomatic/psychiatric sample (n=120) who presented with various psychological and medically unexplained somatic complaints. Although the population sample was significantly older than the two patient groups, they reported significantly fewer AMS and had higher testosterone levels and shorter CAG repeats of the AR. Regression analysis revealed influences of CAGn on the AMS global score and the psychological and somatic subscale only in the two patient samples, while testosterone had some impact on the sexual subscale. Our results suggest that the so-called aging male symptoms show a certain association to androgenicity, but that they are rather unspecific and of multifactorial origin. Other factors contributing to AMS need further clarification.

  15. The Hierarchical Factor Model of ADHD: Invariant across Age and National Groupings?

    ERIC Educational Resources Information Center

    Toplak, Maggie E.; Sorge, Geoff B.; Flora, David B.; Chen, Wai; Banaschewski, Tobias; Buitelaar, Jan; Ebstein, Richard; Eisenberg, Jacques; Franke, Barbara; Gill, Michael; Miranda, Ana; Oades, Robert D.; Roeyers, Herbert; Rothenberger, Aribert; Sergeant, Joseph; Sonuga-Barke, Edmund; Steinhausen, Hans-Christoph; Thompson, Margaret; Tannock, Rosemary; Asherson, Philip; Faraone, Stephen V.

    2012-01-01

    Objective: To examine the factor structure of attention-deficit/hyperactivity disorder (ADHD) in a clinical sample of 1,373 children and adolescents with ADHD and their 1,772 unselected siblings recruited from different countries across a large age range. Hierarchical and correlated factor analytic models were compared separately in the ADHD and…

  16. Integrating Beck's cognitive model and the response style theory in an adolescent sample.

    PubMed

    Winkeljohn Black, Stephanie; Pössel, Patrick

    2015-01-01

    Depression becomes more prevalent as individuals progress from childhood to adulthood. Thus, empirically supported and popular cognitive vulnerability theories to explain depression in adulthood have begun to be tested in younger age groups, particularly adolescence, a time of significant cognitive development. Beck's cognitive theory and the response style theory are well known, empirically supported theories of depression. The current, two-wave longitudinal study (N = 462; mean age = 16.01 years; SD = 0.69; 63.9% female) tested various proposed integrative models of Beck's cognitive theory and the response style theory, as well as the original theories themselves, to determine if and how these cognitive vulnerabilities begin to intertwine in adolescence. Of the integrative models tested-all with structural equation modeling in AMOS 21-the best-fitting integrative model was a moderation model wherein schemata influenced rumination, and rumination then influenced other cognitive variables in Beck's model. Findings revealed that this integrated model fit the data better than the response style theory and explained 1.2% more variance in depressive symptoms. Additionally, multigroup analyses comparing the fit of the best-fitting integrated model across adolescents with clinical and subclinical depressive symptoms revealed that the model was not stable between these two subsamples. However, of the hypotheses relevant to the integrative model, only 1 of the 18 associations was significantly different between the clinical and subclinical samples. Regardless, the integrated model was not superior to the more parsimonious model from Beck's cognitive theory. Implications and limitations are discussed.

  17. Beam Heating of Samples: Modeling and Verification. Part 2

    NASA Technical Reports Server (NTRS)

    Kazmierczak, Michael; Gopalakrishnan, Pradeep; Kumar, Raghav; Banerjee Rupak; Snell, Edward; Bellamy, Henry; Rosenbaum, Gerd; vanderWoerd, Mark

    2006-01-01

    Energy absorbed from the X-ray beam by the sample requires cooling by forced convection (i.e. cryostream) to minimize temperature increase and the damage caused to the sample by the X-ray heating. In this presentation we will first review the current theoretical models and recent studies in the literature, which predict the sample temperature rise for a given set of beam parameters. It should be noted that a common weakness of these previous studies is that none of them provide actual experimental confirmation. This situation is now remedied in our investigation where the problem of x-ray sample heating is taken up once more. We have theoretically investigated, and at the same time, in addition to the numerical computations, performed experiments to validate the predictions. We have modeled, analyzed and experimentally tested the temperature rise of a 1 mm diameter glass sphere (sample surrogate) exposed to an intense synchrotron X-ray beam, while it is being cooled in a uniform flow of nitrogen gas. The heat transfer, including external convection and internal heat conduction was theoretically modeled using CFD to predict the temperature variation in the sphere during cooling and while it was subjected to an undulator (ID sector 19) X-ray beam at the APS. The surface temperature of the sphere during the X-ray beam heating was measured using the infrared camera measurement technique described in a previous talk. The temperatures from the numerical predictions and experimental measurements are compared and discussed. Additional results are reported for the two different sphere sizes and for two different supporting pin orientations.

  18. A Sample of Very Young Field L Dwarfs and Implications for the Brown Dwarf "Lithium Test" at Early Ages

    NASA Astrophysics Data System (ADS)

    Kirkpatrick, J. Davy; Cruz, Kelle L.; Barman, Travis S.; Burgasser, Adam J.; Looper, Dagny L.; Tinney, C. G.; Gelino, Christopher R.; Lowrance, Patrick J.; Liebert, James; Carpenter, John M.; Hillenbrand, Lynne A.; Stauffer, John R.

    2008-12-01

    Using a large sample of optical spectra of late-type dwarfs, we identify a subset of late-M through L field dwarfs that, because of the presence of low-gravity features in their spectra, are believed to be unusually young. From a combined sample of 303 field L dwarfs, we find observationally that 7.6% +/- 1.6% are younger than 100 Myr. This percentage is in agreement with theoretical predictions once observing biases are taken into account. We find that these young L dwarfs tend to fall in the southern hemisphere (decl . < 0°) and may be previously unrecognized, low-mass members of nearby, young associations like Tucana-Horologium, TW Hydrae, β Pictoris, and AB Doradus. We use a homogeneously observed sample of ~150 optical spectra to examine lithium strength as a function of L/T spectral type and further corroborate the trends noted by Kirkpatrick and coworkers. We use our low-gravity spectra to investigate lithium strength as a function of age. The data weakly suggest that for early- to mid-L dwarfs the line strength reaches a maximum for a few × 100 Myr, whereas for much older (few Gyr) and much younger (<100 Myr) L dwarfs the line is weaker or undetectable. We show that a weakening of lithium at lower gravities is predicted by model atmosphere calculations, an effect partially corroborated by existing observational data. Larger samples containing L dwarfs of well-determined ages are needed to further test this empirically. If verified, this result would reinforce the caveat first cited by Kirkpatrick and coworkers that the lithium test should be used with caution when attempting to confirm the substellar nature of the youngest brown dwarfs. Most of the spectroscopic data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous

  19. Imputation for semiparametric transformation models with biased-sampling data

    PubMed Central

    Liu, Hao; Qin, Jing; Shen, Yu

    2012-01-01

    Widely recognized in many fields including economics, engineering, epidemiology, health sciences, technology and wildlife management, length-biased sampling generates biased and right-censored data but often provide the best information available for statistical inference. Different from traditional right-censored data, length-biased data have unique aspects resulting from their sampling procedures. We exploit these unique aspects and propose a general imputation-based estimation method for analyzing length-biased data under a class of flexible semiparametric transformation models. We present new computational algorithms that can jointly estimate the regression coefficients and the baseline function semiparametrically. The imputation-based method under the transformation model provides an unbiased estimator regardless whether the censoring is independent or not on the covariates. We establish large-sample properties using the empirical processes method. Simulation studies show that under small to moderate sample sizes, the proposed procedure has smaller mean square errors than two existing estimation procedures. Finally, we demonstrate the estimation procedure by a real data example. PMID:22903245

  20. "Oxygen supply" as modulator of aging processes: hypoxia and hyperoxia models for aging studies.

    PubMed

    Cataldi, Amelia; Di Giulio, Camillo

    2009-07-01

    Cell growth is regulated by several factors, including oxygen supply, which influence cell metabolism. Aging is characterized by decreased oxygen supply to tissue, a reduction of tissue PO(2) and of the activity of several enzymes and metabolic factors. The oxygen-gradient diffusion at capillary tissue level is essential for the cellular survival, while the homeostasis of the oxygen in the arterial blood is mediated by reflexes sensitive to oxygen decrease and by release of several factors. Aging is correlated with a reduction of cells' oxygen supply concomitant to a parallel decrease in oxygen demand by tissues. Both chronic hypoxia or hyperoxia are considered as stresses. Indeed, in both conditions, free radical species, which damage structural and functional components of the membrane, are generated. ROS (reactive oxygen species) are physiological products of aerobic life and their accumulation affects aging. Because hypoxia per se modulates mitochondria activity, influencing oxygen consumption, hypoxia and aging could share some link. Moreover, the observation that in hypoxia or hyperoxia there is an accumulation of lipofucsine as a general reaction to stress is consistent with the accumulation of such components during aging. Correlation between hypoxia-hyperoxia and life-span remains open until we solve the question of how and why do cells sense oxygen. In other words, to better understand aging we need to know what O(2) species are being sensed by cells. In conclusion, hypoxia and hyperoxia represent an experimental model adequate for studying aging processes.

  1. In vitro 3-D model based on extending time of culture for studying chronological epidermis aging.

    PubMed

    Dos Santos, Morgan; Metral, Elodie; Boher, Aurélie; Rousselle, Patricia; Thepot, Amélie; Damour, Odile

    2015-09-01

    Skin aging is a complex phenomenon in which several mechanisms operate simultaneously. Among them, intrinsic aging is a time-dependent process, which leads to gradual skin changes affecting its structure and function such as thinning down of both epidermal and dermal compartments and a flattening and fragility of the dermo-epidermal junction. Today, several approaches have been proposed for the generation of aged skin in vitro, including skin explants from aged donors and three-dimensional skin equivalent treated by aging-inducing chemical compounds or engineered with human cells isolated from aged donors. The aim of this study was to develop and validate a new in vitro model of aging based on skin equivalent demonstrating the same phenotypic changes that were observed in chronological aging. By using prolonged culture as a proxy for cellular aging, we extended to 120 days the culture time of a skin equivalent model based on collagen-glycosaminoglycan-chitosan porous polymer and engineered with human skin cells from photo-protected sites of young donors. Morphological, immunohistological and ultrastructural analysis at different time points of the culture allowed characterizing the phenotypic changes observed in our model in comparison to samples of non photo-exposed normal human skin from different ages. We firstly confirmed that long-term cultured skin equivalents are still morphologically consistent and functionally active even after 120 days of culture. However, similar to in vivo chronological skin aging a significant decrease of the epidermis thickness as well as the number of keratinocyte expressing proliferation marker Ki67 are observed in extended culture time skin equivalent. Epidermal differentiation markers loricrin, filaggrin, involucrin and transglutaminase, also strongly decreased. Ultrastructural analysis of basement membrane showed typical features of aged skin such as duplication of lamina densa and alterations of hemidesmosomes. Moreover, the

  2. Modeling HIV Prevention Strategies among Two Puerto Rican Samples

    PubMed Central

    Santiago-Rivas, Marimer; Pérez-Jiménez, David

    2012-01-01

    The Information-Motivation-Behavioral Skills model examines factors that are used to initiate and maintain sexual and reproductive health promotion behaviors. The present study evaluated the association among these constructs as it is applied to sexually active heterosexual adults with steady partners, using a Structural Equation Modeling approach. At the same time, it was analyzed if the same model structure could be generalized to two samples of participants that produced the results following two different formats for data collection. Two-hundred ninety one participants completed the Information-Motivation-Behavioral Skills Questionnaire (Spanish version), and 756 participants completed an Internet version on the instrument. The proposed model fits the data for both groups, supporting a predictive and positive relationship among all of the latent variables, with Information predicting Motivation, and Motivation therefore predicting Behavioral Skills. The findings support the notion that there are important issues that need to be addressed when promoting HIV prevention. PMID:23243320

  3. Characterization of plasma thiol redox potential in a common marmoset model of aging.

    PubMed

    Roede, James R; Uppal, Karan; Liang, Yongliang; Promislow, Daniel E L; Wachtman, Lynn M; Jones, Dean P

    2013-01-01

    Due to its short lifespan, ease of use and age-related pathologies that mirror those observed in humans, the common marmoset (Callithrix jacchus) is poised to become a standard nonhuman primate model of aging. Blood and extracellular fluid possess two major thiol-dependent redox nodes involving cysteine (Cys), cystine (CySS), glutathione (GSH) and glutathione disulfide (GSSG). Alteration in these plasma redox nodes significantly affects cellular physiology, and oxidation of the plasma Cys/CySS redox potential (E hCySS) is associated with aging and disease risk in humans. The purpose of this study was to determine age-related changes in plasma redox metabolites and corresponding redox potentials (E h) to further validate the marmoset as a nonhuman primate model of aging. We measured plasma thiol redox states in marmosets and used existing human data with multivariate adaptive regression splines (MARS) to model the relationships between age and redox metabolites. A classification accuracy of 70.2% and an AUC of 0.703 were achieved using the MARS model built from the marmoset redox data to classify the human samples as young or old. These results show that common marmosets provide a useful model for thiol redox biology of aging.

  4. OPC model sampling evaluation and weakpoint "in-situ" improvement

    NASA Astrophysics Data System (ADS)

    Fu, Nan; Elshafie, Shady; Ning, Guoxiang; Roling, Stefan

    2016-10-01

    One of the major challenges of optical proximity correction (OPC) models is to maximize the coverage of real design features using sampling pattern. Normally, OPC model building is based on 1-D and 2-D test patterns with systematically changing pitches alignment with design rules. However, those features with different optical and geometric properties will generate weak-points where OPC simulation cannot precisely predict resist contours on wafer due to the nature of infinite IC designs and limited number of model test patterns. In this paper, optical property data of real design features were collected from full chips and classified to compare with the same kind of data from OPC test patterns. Therefore sample coverage could be visually mapped according to different optical properties. Design features, which are out of OPC capability, were distinguished by their optical properties and marked as weak-points. New patterns with similar optical properties would be added into model build site-list. Further, an alternative and more efficient method was created in this paper to improve the treatment of issue features and remove weak-points without rebuilding models. Since certain classification of optical properties will generate weak-points, an OPC-integrated repair algorithm was developed and implemented to scan full chip for optical properties, locate those features and then optimize OPC treatment or apply precise sizing on site. This is a named "in-situ" weak-point improvement flow which includes issue feature definition, allocation in full chip and real-time improvement.

  5. Reliability of age estimation from iliac auricular surface in a subactual Chilean sample.

    PubMed

    Herrera, María José; Retamal, Rodrigo

    2017-02-14

    The aim of this study was to test the reliability of Osborne et al. (2004) [8] age estimation based on the iliac auricular surface of the ilium. We selected 172 skeletons with documented sex and age-at-death and established six uniformly distributed age intervals for analysis. ANOVA was employed to assess the association of the documented age with sex and the auricular surface classification. We employed Bonferroni post-hoc tests to find any statistical differences across documented ages within each phase of Osborne's criteria. While the ANOVA showed a significant association between the documented age and the auricular surface classification, post-hoc tests found that phases 2 and 3 were the only consecutive phases with significant differences. We argue that a lack of statistical significance between consecutive phases undermines the reliability of this method for forensic purposes especially in middle adults. It may be possible that the collapse of intermediate phases would increase the accuracy of this method.

  6. Predicting and retrodicting intelligence between childhood and old age in the 6-Day Sample of the Scottish Mental Survey 1947.

    PubMed

    Deary, Ian J; Brett, Caroline E

    2015-01-01

    In studies of cognitive ageing it is useful and important to know how stable are the individual differences in cognitive ability from childhood to older age, and also to be able to estimate (retrodict) prior cognitive ability differences from those in older age. Here we contribute to these aims with new data from a follow-up study of the 6-Day Sample of the Scottish Mental Survey of 1947 (original N = 1208). The sample had cognitive, educational, social, and occupational data collected almost annually from age 11 to 27 years. Whereas previous long-term follow-up studies of the Scottish mental surveys are based upon group-administered cognitive tests at a mean age of 11 years, the present sample each had an individually-administered revised Binet test. We traced them for vital status in older age, and some agreed to take several mental tests at age 77 years (N = 131). The National Adult Reading Test at age 77 correlated .72 with the Terman-Merrill revision of the Binet Test at age 11. Adding the Moray House Test No. 12 score from age 11 and educational information took the multiple R to .81 between youth and older age. The equivalent multiple R for fluid general intelligence was .57. When the NART from age 77 was the independent variable (retrodictor) along with educational attainment, the multiple R with the Terman-Merrill IQ at age 11 was .75. No previous studies of the stability of intelligence from childhood to old age, or of the power of the NART to retrodict prior intelligence, have had individually-administered IQ data from youth. About two-thirds, at least, of the variation in verbal ability in old age can be captured by cognitive and educational information from youth. Non-verbal ability is less well predicted. A short test of pronunciation-the NART-and brief educational information can capture well over half of the variation in IQ scores obtained 66 years earlier.

  7. Mathematically modelling the dynamics of cholesterol metabolism and ageing.

    PubMed

    Morgan, A E; Mooney, K M; Wilkinson, S J; Pickles, N A; Mc Auley, M T

    2016-07-01

    Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in the UK. This condition becomes increasingly prevalent during ageing; 34.1% and 29.8% of males and females respectively, over 75 years of age have an underlying cardiovascular problem. The dysregulation of cholesterol metabolism is inextricably correlated with cardiovascular health and for this reason low density lipoprotein cholesterol (LDL-C) and high density lipoprotein cholesterol (HDL-C) are routinely used as biomarkers of CVD risk. The aim of this work was to use mathematical modelling to explore how cholesterol metabolism is affected by the ageing process. To do this we updated a previously published whole-body mathematical model of cholesterol metabolism to include an additional 96 mechanisms that are fundamental to this biological system. Additional mechanisms were added to cholesterol absorption, cholesterol synthesis, reverse cholesterol transport (RCT), bile acid synthesis, and their enterohepatic circulation. The sensitivity of the model was explored by the use of both local and global parameter scans. In addition, acute cholesterol feeding was used to explore the effectiveness of the regulatory mechanisms which are responsible for maintaining whole-body cholesterol balance. It was found that our model behaves as a hypo-responder to cholesterol feeding, while both the hepatic and intestinal pools of cholesterol increased significantly. The model was also used to explore the effects of ageing in tandem with three different cholesterol ester transfer protein (CETP) genotypes. Ageing in the presence of an atheroprotective CETP genotype, conferring low CETP activity, resulted in a 0.6% increase in LDL-C. In comparison, ageing with a genotype reflective of high CETP activity, resulted in a 1.6% increase in LDL-C. Thus, the model has illustrated the importance of CETP genotypes such as I405V, and their potential role in healthy ageing.

  8. Justification of sexual reproduction by modified Penna model of ageing

    NASA Astrophysics Data System (ADS)

    Sá Martins, J. S.; Stauffer, D.

    2001-05-01

    We generalize the standard Penna bit-string model of biological ageing by assuming that each deleterious mutation diminishes the survival probability in every time interval by a small percentage. This effect is added to the usual lethal but age-dependent effect of the same mutation. We then find strong advantages or disadvantages of sexual reproduction (with males and females) compared to asexual cloning, depending on parameters.

  9. Physical Models of Seismic-Attenuation Measurements on Lab Samples

    NASA Astrophysics Data System (ADS)

    Coulman, T. J.; Morozov, I. B.

    2012-12-01

    Seismic attenuation in Earth materials is often measured in the lab by using low-frequency forced oscillations or static creep experiments. The usual assumption in interpreting and even designing such experiments is the "viscoelastic" behavior of materials, i.e., their description by the notions of a Q-factor and material memory. However, this is not the only theoretical approach to internal friction, and it also involves several contradictions with conventional mechanics. From the viewpoint of mechanics, the frequency-dependent Q becomes a particularly enigmatic property attributed to the material. At the same time, the behavior of rock samples in seismic-attenuation experiments can be explained by a strictly mechanical approach. We use this approach to simulate such experiments analytically and numerically for a system of two cylinders consisting of a rock sample and elastic standard undergoing forced oscillations, and also for a single rock sample cylinder undergoing static creep. The system is subject to oscillatory compression or torsion, and the phase-lag between the sample and standard is measured. Unlike in the viscoelastic approach, a full Lagrangian formulation is considered, in which material anelasticity is described by parameters of "solid viscosity" and a dissipation function from which the constitutive equation is derived. Results show that this physical model of anelasticity predicts creep results very close to those obtained by using empirical Burger's bodies or Andrade laws. With nonlinear (non-Newtonian) solid viscosity, the system shows an almost instantaneous initial deformation followed by slow creep towards an equilibrium. For Aheim Dunite, the "rheologic" parameters of nonlinear viscosity are υ=0.79 and η=2.4 GPa-s. Phase-lag results for nonlinear viscosity show Q's slowly decreasing with frequency. To explain a Q increasing with frequency (which is often observed in the lab and in the field), one has to consider nonlinear viscosity with

  10. Social Work Faculty's Knowledge of Aging: Results from a National Sample

    ERIC Educational Resources Information Center

    Wang, Donna S.; Chonody, Jill M.; Krase, Kathryn

    2013-01-01

    Social work students have reported in previous studies that they receive insufficient coursework and training to work effectively with older adults. A critical factor in these deficiencies may be the level of knowledge of social work faculty. This study sought to assess social work faculty's knowledge of aging using the Knowledge of Aging for…

  11. Financial capability, asset ownership, and later-age immigration: evidence from a sample of low-income older Asian immigrants.

    PubMed

    Nam, Yunju; Lee, Eun Jeong; Huang, Jin; Kim, Junpyo

    2015-01-01

    We examined financial capability and asset ownership among low-income older Asian immigrants with special attention given to later-age immigrants who came to the United States when they were 55 years old or older. Survey data collected from supported employment program participants (N = 150) were used. The analyses demonstrated a low level of financial knowledge and asset ownership in the sample. The findings also indicated that later-age immigrants' financial-management skills, knowledge of social programs, and asset ownership were significantly lower than those of young-age immigrants. These findings call for active interventions to enhance economic security among low-income older Asian immigrants.

  12. Differences in physical fitness and gross motor coordination in boys aged 6-12 years specializing in one versus sampling more than one sport.

    PubMed

    Fransen, Job; Pion, Johan; Vandendriessche, Joric; Vandorpe, Barbara; Vaeyens, Roel; Lenoir, Matthieu; Philippaerts, Renaat M

    2012-01-01

    The Developmental Model of Sports Participation proposes two pathways towards expertise in sports between 6 and 12 years of age: early specialization and early diversification. This study investigated the effect of sampling various sports and of spending many or few hours in sports on fitness and gross motor coordination. Altogether, 735 boys in three age groups (6-8, 8-10, and 10-12 years) were profiled using a fitness test battery. A computerized physical activity questionnaire was used to obtain data on sports participation. In the eldest group, (M)ANCOVA showed a positive effect of sampling various sports on strength, speed, endurance, and gross motor coordination (P < 0.05). A positive effect of many hours per week spent in sports was apparent in every age group. These data suggest an acute positive effect of many hours in sports and a latent positive effect of early sampling on fitness and gross motor coordination. Multiple comparisons revealed that boys aged 10-12 years, who spent many hours in various sports, performed better on standing broad jump (P < 0.05) and gross motor coordination (P < 0.05) than boys specializing in a single sport. Therefore, our results highlight the importance of spending many hours in sports and sampling various sports in the development of fitness and gross motor coordination.

  13. Using Structural Equation Modeling to Assess Functional Connectivity in the Brain: Power and Sample Size Considerations.

    PubMed

    Sideridis, Georgios; Simos, Panagiotis; Papanicolaou, Andrew; Fletcher, Jack

    2014-10-01

    The present study assessed the impact of sample size on the power and fit of structural equation modeling applied to functional brain connectivity hypotheses. The data consisted of time-constrained minimum norm estimates of regional brain activity during performance of a reading task obtained with magnetoencephalography. Power analysis was first conducted for an autoregressive model with 5 latent variables (brain regions), each defined by 3 indicators (successive activity time bins). A series of simulations were then run by generating data from an existing pool of 51 typical readers (aged 7.5-12.5 years). Sample sizes ranged between 20 and 1,000 participants and for each sample size 1,000 replications were run. Results were evaluated using chi-square Type I errors, model convergence, mean RMSEA (root mean square error of approximation) values, confidence intervals of the RMSEA, structural path stability, and D-Fit index values. Results suggested that 70 to 80 participants were adequate to model relationships reflecting close to not so close fit as per MacCallum et al.'s recommendations. Sample sizes of 50 participants were associated with satisfactory fit. It is concluded that structural equation modeling is a viable methodology to model complex regional interdependencies in brain activation in pediatric populations.

  14. Applicability of Demirjian's four methods and Willems method for age estimation in a sample of Turkish children.

    PubMed

    Akkaya, Nursel; Yilanci, Hümeyra Özge; Göksülük, Dinçer

    2015-09-01

    The aim of this study was to evaluate applicability of five dental methods including Demirjian's original, revised, four teeth, and alternate four teeth methods and Willems method for age estimation in a sample of Turkish children. Panoramic radiographs of 799 children (412 females, 387 males) aged between 2.20 and 15.99years were examined by two observers. A repeated measures ANOVA was performed to compare dental methods among gender and age groups. All of the five methods overestimated the chronological age on the average. Among these, Willems method was found to be the most accurate method, which showed 0.07 and 0.15years overestimation for males and females, respectively. It was followed by Demirjian's four teeth methods, revised and original methods. According to the results, Willems method can be recommended for dental age estimation of Turkish children in forensic applications.

  15. Tuberculosis in Cape Town: an age-structured transmission model

    PubMed Central

    Blaser, Nello; Zahnd, Cindy; Hermans, Sabine; Salazar-Vizcaya, Luisa; Estill, Janne; Morrow, Carl; Egger, Matthias; Keiser, Olivia; Wood, Robin

    2015-01-01

    Background Tuberculosis (TB) is the leading cause of death in South Africa. The burden of disease varies by age, with peaks in TB notification rates in the HIV-negative population at ages 0-5, 20-24 and 45-49 years. There is little variation between age groups in the rates in the HIV-positive population. The drivers of this age pattern remain unknown. Methods We developed an age-structured simulation model of Mycobacterium tuberculosis (Mtb) transmission in Cape Town, South Africa. We considered five states of TB progression: susceptible, infected (latent TB), active TB, treated TB and treatment default. Latently infected individuals could be re-infected; a previous Mtb infection slowed progression to active disease. We further considered three states of HIV progression: HIV negative, HIV positive, on antiretroviral therapy. To parameterize the model, we analysed treatment outcomes from the Cape Town electronic TB register, social mixing patterns from a Cape Town community and literature estimates for other parameters. To investigate the main drivers behind the age patterns, we conducted sensitivity analyses on all parameters related to the age structure. Results The model replicated the age patterns in HIV-negative TB notification rates of Cape Town in 2009. Simulated TB notification rate in HIV-negative patients was 1,000/100,000 person-years (pyrs) in children aged < 5 years and decreased to 51/100,000 in children 5-15 years. The peak in early adulthood occurred at 25-29 years (463/100,000 pyrs). After a subsequent decline, simulated TB notification rates gradually increased from the age of 30 years. Sensitivity analyses showed that the dip after the early adult peak was due to the protective effect of latent TB and that retreatment TB was mainly responsible for the rise in TB notification rates from the age of 30 years. Conclusion The protective effect of a first latent infection on subsequent infections and the faster progression in previously treated patients

  16. Sample size matters: investigating the effect of sample size on a logistic regression susceptibility model for debris flows

    NASA Astrophysics Data System (ADS)

    Heckmann, T.; Gegg, K.; Gegg, A.; Becht, M.

    2014-02-01

    Predictive spatial modelling is an important task in natural hazard assessment and regionalisation of geomorphic processes or landforms. Logistic regression is a multivariate statistical approach frequently used in predictive modelling; it can be conducted stepwise in order to select from a number of candidate independent variables those that lead to the best model. In our case study on a debris flow susceptibility model, we investigate the sensitivity of model selection and quality to different sample sizes in light of the following problem: on the one hand, a sample has to be large enough to cover the variability of geofactors within the study area, and to yield stable and reproducible results; on the other hand, the sample must not be too large, because a large sample is likely to violate the assumption of independent observations due to spatial autocorrelation. Using stepwise model selection with 1000 random samples for a number of sample sizes between n = 50 and n = 5000, we investigate the inclusion and exclusion of geofactors and the diversity of the resulting models as a function of sample size; the multiplicity of different models is assessed using numerical indices borrowed from information theory and biodiversity research. Model diversity decreases with increasing sample size and reaches either a local minimum or a plateau; even larger sample sizes do not further reduce it, and they approach the upper limit of sample size given, in this study, by the autocorrelation range of the spatial data sets. In this way, an optimised sample size can be derived from an exploratory analysis. Model uncertainty due to sampling and model selection, and its predictive ability, are explored statistically and spatially through the example of 100 models estimated in one study area and validated in a neighbouring area: depending on the study area and on sample size, the predicted probabilities for debris flow release differed, on average, by 7 to 23 percentage points. In

  17. Sample size matters: investigating the effect of sample size on a logistic regression debris flow susceptibility model

    NASA Astrophysics Data System (ADS)

    Heckmann, T.; Gegg, K.; Gegg, A.; Becht, M.

    2013-06-01

    Predictive spatial modelling is an important task in natural hazard assessment and regionalisation of geomorphic processes or landforms. Logistic regression is a multivariate statistical approach frequently used in predictive modelling; it can be conducted stepwise in order to select from a number of candidate independent variables those that lead to the best model. In our case study on a debris flow susceptibility model, we investigate the sensitivity of model selection and quality to different sample sizes in light of the following problem: on the one hand, a sample has to be large enough to cover the variability of geofactors within the study area, and to yield stable results; on the other hand, the sample must not be too large, because a large sample is likely to violate the assumption of independent observations due to spatial autocorrelation. Using stepwise model selection with 1000 random samples for a number of sample sizes between n = 50 and n = 5000, we investigate the inclusion and exclusion of geofactors and the diversity of the resulting models as a function of sample size; the multiplicity of different models is assessed using numerical indices borrowed from information theory and biodiversity research. Model diversity decreases with increasing sample size and reaches either a local minimum or a plateau; even larger sample sizes do not further reduce it, and approach the upper limit of sample size given, in this study, by the autocorrelation range of the spatial datasets. In this way, an optimised sample size can be derived from an exploratory analysis. Model uncertainty due to sampling and model selection, and its predictive ability, are explored statistically and spatially through the example of 100 models estimated in one study area and validated in a neighbouring area: depending on the study area and on sample size, the predicted probabilities for debris flow release differed, on average, by 7 to 23 percentage points. In view of these results, we

  18. TOWARD PRECISE AGES FOR SINGLE STARS IN THE FIELD. GYROCHRONOLOGY CONSTRAINTS AT SEVERAL Gyr USING WIDE BINARIES. I. AGES FOR INITIAL SAMPLE

    SciTech Connect

    Chaname, Julio; Ramirez, Ivan

    2012-02-10

    We present a program designed to obtain age-rotation measurements of solar-type dwarfs to be used in the calibration of gyrochronology relations at ages of several Gyr. This is a region of parameter space crucial for the large-scale study of the Milky Way, and where the only constraint available today is that provided by the Sun. Our program takes advantage of a set of wide binaries selected so that one component is an evolved star and the other is a main-sequence star of FGK type. In this way, we obtain the age of the system from the evolved star, while the rotational properties of the main-sequence component provide the information relevant for gyrochronology regarding the spin-down of solar-type stars. By mining currently available catalogs of wide binaries, we assemble a sample of 37 pairs well positioned for our purposes: 19 with turnoff or subgiant primaries and 18 with white dwarf components. Using high-resolution optical spectroscopy, we measure precise stellar parameters for a subset of 15 of the pairs with turnoff/subgiant components and use these to derive isochronal ages for the corresponding systems. Ages for 16 of the 18 pairs with white dwarf components are taken from the literature. The ages of this initial sample of 31 wide binaries range from 1 to 9 Gyr, with precisions better than {approx}20% for almost half of these systems. When combined with measurements of the rotation period of their main-sequence components, these wide binary systems would potentially provide a similar number of points useful for the calibration of gyrochronology relations at very old ages.

  19. Cellular senescence in the Penna model of aging

    NASA Astrophysics Data System (ADS)

    Periwal, Avikar

    2013-11-01

    Cellular senescence is thought to play a major role in age-related diseases, which cause nearly 67% of all human deaths worldwide. Recent research in mice showed that exercising mice had higher levels of telomerase, an enzyme that helps maintain telomere length, than nonexercising mice. A commonly used model for biological aging was proposed by Penna. I propose a modification of the Penna model that incorporates cellular senescence and find an analytical steady-state solution following Coe, Mao, and Cates [Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.89.288103 89, 288103 (2002)]. I find that models corresponding to delayed cellular senescence have younger populations that live longer. I fit the model to the United Kingdom's death distribution, which the original Penna model cannot do.

  20. Motif Yggdrasil: sampling sequence motifs from a tree mixture model.

    PubMed

    Andersson, Samuel A; Lagergren, Jens

    2007-06-01

    In phylogenetic foot-printing, putative regulatory elements are found in upstream regions of orthologous genes by searching for common motifs. Motifs in different upstream sequences are subject to mutations along the edges of the corresponding phylogenetic tree, consequently taking advantage of the tree in the motif search is an appealing idea. We describe the Motif Yggdrasil sampler; the first Gibbs sampler based on a general tree that uses unaligned sequences. Previous tree-based Gibbs samplers have assumed a star-shaped tree or partially aligned upstream regions. We give a probabilistic model (MY model) describing upstream sequences with regulatory elements and build a Gibbs sampler with respect to this model. The model allows toggling, i.e., the restriction of a position to a subset of nucleotides, but does not require aligned sequences nor edge lengths, which may be difficult to come by. We apply the collapsing technique to eliminate the need to sample nuisance parameters, and give a derivation of the predictive update formula. We show that the MY model improves the modeling of difficult motif instances and that the use of the tree achieves a substantial increase in nucleotide level correlation coefficient both for synthetic data and 37 bacterial lexA genes. We investigate the sensitivity to errors in the tree and show that using random trees MY sampler still has a performance similar to the original version.

  1. Correction of deposit ages for inherited ages of charcoal: implications for sediment dynamics inferred from random sampling of deposits on headwater valley floors

    NASA Astrophysics Data System (ADS)

    Frueh, W. Terry; Lancaster, Stephen T.

    2014-03-01

    Inherited age is defined herein as the difference between times of carbon fixation in a material and deposition of that material within sediments from which it is eventually sampled in order to estimate deposit age via radiocarbon dating. Inheritance generally leads to over-estimation of the age by an unknown amount and therefore represents unquantified bias and uncertainty that could potentially lead to erroneous inferences. Inherited ages in charcoal are likely to be larger, and therefore detectable relative to analytic error, where forests are dominated by longer-lived trees, material is stored for longer periods upslope, and downstream post-fire delivery of that material is dominated by mass movements, such as in the near-coastal mountains of northwestern North America. Inherited age distribution functions were estimated from radiocarbon dating of 126 charcoal pieces from 14 stream-bank exposures of debris-flow deposits, fluvial fines, and fluvial gravels along a headwater stream in the southern Oregon Coast Range, USA. In the region, these 3 facies are representative of the nearly continuous coalescing fan-fill complexes blanketing valley floors of headwater streams where the dominant transport mechanism shifts from debris-flow to fluvial. Within each depositional unit, and for each charcoal piece within that unit, convolution of the calibrated age distribution with that of the youngest piece yielded an inherited age distribution for the unit. Fits to the normalized sums of inherited age distributions for units of like facies provided estimates of facies-specific inherited age distribution functions. Finally, convolution of these distribution functions with calibrated deposit age distributions yielded corrections to published valley-floor deposit ages and residence time distributions from nearby similar sites. Residence time distributions were inferred from the normalized sums of distributions of ˜30 deposit ages at each of 4 sites: 2 adjacent valley reaches

  2. Volcanic Aerosol Evolution: Model vs. In Situ Sampling

    NASA Astrophysics Data System (ADS)

    Pfeffer, M. A.; Rietmeijer, F. J.; Brearley, A. J.; Fischer, T. P.

    2002-12-01

    Volcanoes are the most significant non-anthropogenic source of tropospheric aerosols. Aerosol samples were collected at different distances from 92°C fumarolic source at Poás Volcano. Aerosols were captured on TEM grids coated by a thin C-film using a specially designed collector. In the sampling, grids were exposed to the plume for 30-second intervals then sealed and frozen to prevent reaction before ATEM analysis to determine aerosol size and chemistry. Gas composition was established using gas chromatography, wet chemistry techniques, AAS and Ion Chromatography on samples collected directly from a fumarolic vent. SO2 flux was measured remotely by COSPEC. A Gaussian plume dispersion model was used to model concentrations of the gases at different distances down-wind. Calculated mixing ratios of air and the initial gas species were used as input to the thermo-chemical model GASWORKS (Symonds and Reed, Am. Jour. Sci., 1993). Modeled products were compared with measured aerosol compositions. Aerosols predicted to precipitate out of the plume one meter above the fumarole are [CaSO4, Fe2.3SO4, H2SO4, MgF2. Na2SO4, silica, water]. Where the plume leaves the confines of the crater, 380 meters distant, the predicted aerosols are the same, excepting FeF3 replacing Fe2.3SO4. Collected aerosols show considerable compositional differences between the sampling locations and are more complex than those predicted. Aerosols from the fumarole consist of [Fe +/- Si,S,Cl], [S +/- O] and [Si +/- O]. Aerosols collected on the crater rim consist of the same plus [O,Na,Mg,Ca], [O,Si,Cl +/- Fe], [Fe,O,F] and [S,O +/- Mg,Ca]. The comparison between results obtained by the equilibrium gas model and the actual aerosol compositions shows that an assumption of chemical and thermal equilibrium evolution is invalid. The complex aerosols collected contrast the simple formulae predicted. These findings show that complex, non-equilibrium chemical reactions take place immediately upon volcanic

  3. De novo protein conformational sampling using a probabilistic graphical model

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Debswapna; Cheng, Jianlin

    2015-11-01

    Efficient exploration of protein conformational space remains challenging especially for large proteins when assembling discretized structural fragments extracted from a protein structure data database. We propose a fragment-free probabilistic graphical model, FUSION, for conformational sampling in continuous space and assess its accuracy using ‘blind’ protein targets with a length up to 250 residues from the CASP11 structure prediction exercise. The method reduces sampling bottlenecks, exhibits strong convergence, and demonstrates better performance than the popular fragment assembly method, ROSETTA, on relatively larger proteins with a length of more than 150 residues in our benchmark set. FUSION is freely available through a web server at http://protein.rnet.missouri.edu/FUSION/.

  4. Comparing interval estimates for small sample ordinal CFA models

    PubMed Central

    Natesan, Prathiba

    2015-01-01

    Robust maximum likelihood (RML) and asymptotically generalized least squares (AGLS) methods have been recommended for fitting ordinal structural equation models. Studies show that some of these methods underestimate standard errors. However, these studies have not investigated the coverage and bias of interval estimates. An estimate with a reasonable standard error could still be severely biased. This can only be known by systematically investigating the interval estimates. The present study compares Bayesian, RML, and AGLS interval estimates of factor correlations in ordinal confirmatory factor analysis models (CFA) for small sample data. Six sample sizes, 3 factor correlations, and 2 factor score distributions (multivariate normal and multivariate mildly skewed) were studied. Two Bayesian prior specifications, informative and relatively less informative were studied. Undercoverage of confidence intervals and underestimation of standard errors was common in non-Bayesian methods. Underestimated standard errors may lead to inflated Type-I error rates. Non-Bayesian intervals were more positive biased than negatively biased, that is, most intervals that did not contain the true value were greater than the true value. Some non-Bayesian methods had non-converging and inadmissible solutions for small samples and non-normal data. Bayesian empirical standard error estimates for informative and relatively less informative priors were closer to the average standard errors of the estimates. The coverage of Bayesian credibility intervals was closer to what was expected with overcoverage in a few cases. Although some Bayesian credibility intervals were wider, they reflected the nature of statistical uncertainty that comes with the data (e.g., small sample). Bayesian point estimates were also more accurate than non-Bayesian estimates. The results illustrate the importance of analyzing coverage and bias of interval estimates, and how ignoring interval estimates can be misleading

  5. Modeling and Simulation of a Tethered Harpoon for Comet Sampling

    NASA Technical Reports Server (NTRS)

    Quadrelli, Marco B.

    2014-01-01

    This paper describes the development of a dynamic model and simulation results of a tethered harpoon for comet sampling. This model and simulation was done in order to carry out an initial sensitivity analysis for key design parameters of the tethered system. The harpoon would contain a canister which would collect a sample of soil from a cometary surface. Both a spring ejected canister and a tethered canister are considered. To arrive in close proximity of the spacecraft at the end of its trajectory so it could be captured, the free-flying canister would need to be ejected at the right time and with the proper impulse, while the tethered canister must be recovered by properly retrieving the tether at a rate that would avoid an excessive amplitude of oscillatory behavior during the retrieval. The paper describes the model of the tether dynamics and harpoon penetration physics. The simulations indicate that, without the tether, the canister would still reach the spacecraft for collection, that the tether retrieval of the canister would be achievable with reasonable fuel consumption, and that the canister amplitude upon retrieval would be insensitive to variations in vertical velocity dispersion.

  6. Thermal modeling of core sampling in flammable gas waste tanks. Part 2: Rotary-mode sampling

    SciTech Connect

    Unal, C.; Poston, D.; Pasamehmetoglu, K.O.; Witwer, K.S.

    1997-08-01

    The radioactive waste stored in underground storage tanks at Hanford site includes mixtures of sodium nitrate and sodium nitrite with organic compounds. The waste can produce undesired violent exothermic reactions when heated locally during the rotary-mode sampling. Experiments are performed varying the downward force at a maximum rotational speed of 55 rpm and minimum nitrogen purge flow of 30 scfm. The rotary drill bit teeth-face temperatures are measured. The waste is simulated with a low thermal conductivity hard material, pumice blocks. A torque meter is used to determine the energy provided to the drill string. The exhaust air-chip temperature as well as drill string and drill bit temperatures and other key operating parameters were recorded. A two-dimensional thermal model is developed. The safe operating conditions were determined for normal operating conditions. A downward force of 750 at 55 rpm and 30 scfm nitrogen purge flow was found to yield acceptable substrate temperatures. The model predicted experimental results reasonably well. Therefore, it could be used to simulate abnormal conditions to develop procedures for safe operations.

  7. The Bender-Gestalt psychopathology scale: failure to infer validity in a school-aged sample.

    PubMed

    Rossini, E D

    1993-06-01

    The concurrent validity of Hutt's (1977) empirical psychopathology scale of the Bender Visual-Motor Gestalt Test was evaluated among three groups of younger school-aged children within the 7-to-10- year age range (M = 109.1): adjustment disordered, conduct disordered, and nonclinical controls (n = 40/group). Excellent interscorer reliability was achieved with approximately 2 hr of self-study of the scoring manual. Although the conduct-disordered group was significantly more immature on Koppitz' Developmental Scoring System, there were no significant differences among groups on the psychopathology scale when visual-motor development was covaried (M = 50.5). This was an unexpected result, given Hutt's initial validation study among school-aged children. The psychopathology scale was not inferred to be valid among adolescents in the only known concurrent validation study. Pending supportive validation research, the psychopathology scale should not be employed in the clinical assessment of younger school-aged children.

  8. Personality change over 40 years of adulthood: hierarchical linear modeling analyses of two longitudinal samples.

    PubMed

    Helson, Ravenna; Jones, Constance; Kwan, Virginia S Y

    2002-09-01

    Normative personality change over 40 years was shown in 2 longitudinal cohorts with hierarchical linear modeling of California Psychological Inventory data obtained at multiple times between ages 21-75. Although themes of change and the paucity of differences attributable to gender and cohort largely supported findings of multiethnic cross-sectional samples, the authors also found much quadratic change and much individual variability. The form of quadratic change supported predictions about the influence of period of life and social climate as factors in change over the adult years: Scores on Dominance and Independence peaked in the middle age of both cohorts, and scores on Responsibility were lowest during peak years of the culture of individualism. The idea that personality change is most pronounced before age 30 and then reaches a plateau received no support.

  9. Activities, family relationships and feelings about aging in a multicultural elderly sample.

    PubMed

    Harris, M B; Begay, C; Page, P

    1989-01-01

    This study looked at ethnic and gender differences in activities, family relationships, and feelings about aging in 128 American Indian, Anglo, and Hispanic adults over sixty. Reading, visiting, and watching television were the most popular activities for all subjects, with a number of sex and ethnic differences appearing. Most subjects reported improved relationships with their families on various dimensions after turning sixty. A number of advantages and disadvantages of aging were mentioned. Few ethnic or gender differences were found on these latter variables.

  10. Some correlation of rock exposure ages and regolith dynamics. [in lunar samples

    NASA Technical Reports Server (NTRS)

    Horz, F.; Gibbons, R. V.; Gault, D. E.; Hartung, J. B.; Brownlee, D. E.

    1975-01-01

    Exposure age information on lunar rocks and regolith turnover rates are correlated. If plotted in a cumulative fashion, the distribution of spallogenic noble-gas exposure ages is remarkably parallel to the rate at which various fractions of the regolith surface are cratered and/or excavated. It appears that the rate at which lunar rocks are excavated from within the regolith is strongly controlled by the impact environment. Some suggestions for future refinement of regolith dynamics are presented.

  11. Estimated Prevalence of Attention-Deficit/Hyperactivity Disorder in a Sample of Panamanian School-Aged Children

    ERIC Educational Resources Information Center

    Sanchez, Emelyn Y.; Velarde, Silvia; Britton, Gabrielle B.

    2011-01-01

    The present study investigated the prevalence of ADHD in a school sample of children ages 6-11 years in the city of Panama. The assessment battery included the Conners' Parent and Teacher Rating Scales, the Structured Developmental History of the Behavioral Assessment System for Children (BASC-2), and the Wechsler Intelligence Scale for Children…

  12. Feeding Practices and Styles Used by a Diverse Sample of Low-Income Parents of Preschool-age Children

    ERIC Educational Resources Information Center

    Ventura, Alison K.; Gromis, Judy C.; Lohse, Barbara

    2010-01-01

    Objective: To describe the feeding practices and styles used by a diverse sample of low-income parents of preschool-age children. Design: Thirty- to 60-minute meetings involving a semistructured interview and 2 questionnaires administered by the interviewer. Setting: Low-income communities in Philadelphia, PA. Participants: Thirty-two parents of…

  13. Chemical analyses and K-Ar ages of samples from 13 drill holes, Medicine Lake volcano, California

    USGS Publications Warehouse

    Donnelly-Nolan, Julie M.

    2006-01-01

    Chemical analyses and K-Ar ages are presented for rocks sampled from drill holes at Medicine Lake volcano, northern California. A location map and a cross-section are included, as are separate tables for drill hole information, major and trace element data, and for K-Ar dates.

  14. Associations among Child Care, Family, and Behavior Outcomes in a Nation-Wide Sample of Preschool-Aged Children

    ERIC Educational Resources Information Center

    Romano, Elisa; Kohen, Dafna; Findlay, Leanne C.

    2010-01-01

    Canadian data based on maternal reports for a nationally representative sample of 4,521 4-5-year-olds were used to examine associations among child care, family factors, and behaviors in preschool-aged children. Linear regressions testing for direct and moderated associations indicated that regulated home-based care was associated with less…

  15. An Examination of the RCMAS-2 Scores across Gender, Ethnic Background, and Age in a Large Asian School Sample

    ERIC Educational Resources Information Center

    Ang, Rebecca P.; Lowe, Patricia A.; Yusof, Noradlin

    2011-01-01

    The present study investigated the factor structure, reliability, convergent and discriminant validity, and U.S. norms of the Revised Children's Manifest Anxiety Scale, Second Edition (RCMAS-2; C. R. Reynolds & B. O. Richmond, 2008a) scores in a Singapore sample of 1,618 school-age children and adolescents. Although there were small…

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

    EPA Science Inventory

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

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

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

  17. Modeling transient groundwater age in the Middle Wairarapa Valley, New Zealand

    NASA Astrophysics Data System (ADS)

    Evison, R.; Daughney, C.; Jackson, B. M.; Toews, M. W.; Cornaton, F. J.; Gyopari, M.; McAllister, D.

    2013-12-01

    Age information provides insights into groundwater flow and transport processes and thus enables better groundwater management. It is accepted that groundwater is composed of a mixture of water with different ages. For example, a groundwater sample with an old mean age may still contain a fraction of young water; recent contamination is therefore a potential risk that may not be conveyed by consideration of the mean age alone. This project focuses on catchment-scale evaluation of the full distribution of groundwater age as a function of space and time in the 270 km2 Middle Wairarapa Valley, New Zealand. The Wairarapa Valley exhibits complex interactions between its rivers and shallow aquifers. Agriculture is an integral part of the region with widespread irrigation and nutrient application. This requires effective regional management due to the risk of contamination and depletion of groundwater reservoirs. The starting point was a transient finite-element groundwater flow model originally developed by Greater Wellington Regional Council (GWRC). The GWRC flow model was converted to simulate transport of the age tracer tritium using Ground Water (GW) software. There are several techniques to calibrate groundwater models and assess appropriate parameter values, all of which have the problem of non-uniqueness. In this study the Gauss-Marquardt-Levenberg method was utilized to calibrate the model (through PEST), but in order to increase robustness, a classic Monte Carlo method with uniform random sampling was also used to sample the domain's global range of flow and transport parameters. This provided an increased measure of confidence in model output, as the global range of parameter values could be explored, which is not achieved via the localized Gauss-Marquardt-Levenberg parameter estimation scheme. The calibration objective with both methods used least squares minimization between the simulated and observed hydraulic head levels and tritium concentrations. GW

  18. Past and recent attempts to model mortality at all ages.

    PubMed

    Hartmann, M

    1987-01-01

    "Most laws of mortality are partial in the sense that they apply only to a broad age group and not to all ages. This paper focuses on three laws of mortality that apply to all ages. Two of them were developed by the actuaries Thiele and Wittstein in the late 19th century. The third, developed by Heligman and Pollard, is of recent origin. The three laws are discussed with references to Scandinavian mortality data. The results suggest that the most recently proposed law can be used for generation of model life tables, for making population projections, simulations, and other statistical work where there is a need for a realistic model of human mortality."

  19. Sparse model selection in the highly under-sampled regime

    NASA Astrophysics Data System (ADS)

    Bulso, Nicola; Marsili, Matteo; Roudi, Yasser

    2016-09-01

    We propose a method for recovering the structure of a sparse undirected graphical model when very few samples are available. The method decides about the presence or absence of bonds between pairs of variable by considering one pair at a time and using a closed form formula, analytically derived by calculating the posterior probability for every possible model explaining a two body system using Jeffreys prior. The approach does not rely on the optimization of any cost functions and consequently is much faster than existing algorithms. Despite this time and computational advantage, numerical results show that for several sparse topologies the algorithm is comparable to the best existing algorithms, and is more accurate in the presence of hidden variables. We apply this approach to the analysis of US stock market data and to neural data, in order to show its efficiency in recovering robust statistical dependencies in real data with non-stationary correlations in time and/or space.

  20. Hierarchical Bayesian Modeling, Estimation, and Sampling for Multigroup Shape Analysis

    PubMed Central

    Yu, Yen-Yun; Fletcher, P. Thomas; Awate, Suyash P.

    2016-01-01

    This paper proposes a novel method for the analysis of anatomical shapes present in biomedical image data. Motivated by the natural organization of population data into multiple groups, this paper presents a novel hierarchical generative statistical model on shapes. The proposed method represents shapes using pointsets and defines a joint distribution on the population’s (i) shape variables and (ii) object-boundary data. The proposed method solves for optimal (i) point locations, (ii) correspondences, and (iii) model-parameter values as a single optimization problem. The optimization uses expectation maximization relying on a novel Markov-chain Monte-Carlo algorithm for sampling in Kendall shape space. Results on clinical brain images demonstrate advantages over the state of the art. PMID:25320776

  1. Age and Social Context Modulate the Effect of Anxiety on Risk-taking in Pediatric Samples

    PubMed Central

    Rosen, Dana; Patel, Nilam; Pavletic, Nevia; Grillon, Christian; Pine, Daniel S.

    2016-01-01

    Although risk-taking has been studied from a developmental perspective, no study has examined how anxiety, age, risk-valence and social context interact to modulate decision-making in youths. This study probes this question using a risk-taking task, the Stunt Task, in clinically anxious children (n=17, 10 F, age=8.3–12.1 years), healthy children (n=13, 4 F, age=9.3–12.2 years), clinically anxious adolescents (n=18, 6 F, age=12.3–17.7 years), and healthy adolescents (n =14, 10 F, age=12.5–17.3 years). Social context was manipulated: in one condition, participants were led to believe that a group of peers were observing and judging their performance (peer-judge), while, in the other condition, they were led to believe that peers were not observing them (control). Only anxious children showed an influence of social context on their risk-taking behavior. Specifically, anxious children bet significantly less and had slower reaction times (RT) during the peer-judge than control condition. However, across social conditions, risk-valence modulated RT differently in function of age and diagnosis. Anxious children were slower on the positive-valence risky trial, whereas anxious adolescents were slower on the negative-valence risky trials relative to their respective healthy peers. In conclusion, clinically anxious children were the only group that was sensitive (risk-averse) to the effect of a negative peer-judge context. The negative peer-judge context did not affect risky decision-making in adolescents, whether they were anxious or healthy. Future work using a stronger aversive social context might be more effective at influencing risky behavior in this age group. PMID:26659306

  2. Evaluating Quality of Aged Archival Formalin-Fixed Paraffin-Embedded Samples for RNA-Sequencing

    EPA Science Inventory

    Archival formalin-fixed paraffin-embedded (FFPE) samples offer a vast, untapped source of genomic data for biomarker discovery. However, the quality of FFPE samples is often highly variable, and conventional methods to assess RNA quality for RNA-sequencing (RNA-seq) are not infor...

  3. Digital Coordinates and Age of More Than 13,000 Foraminifers Samples Collected by Chevron Petroleum Geologists in California

    USGS Publications Warehouse

    Malmblorg, William T.; West, William B.; Brabb, Earl E.; Parker, John M.

    2008-01-01

    The general location and age of more than 33,500 mostly foraminifer samples from Chevron surface localities in nearly 600 U.S. Geological Survey (USGS) 7.5' quadrangles from California were provided by Brabb and Parker (2003). Barren and non-diagnostic samples plus many that have no paleontologic information were omitted to provide a revised list for more than 27,000 of these samples by Brabb and Parker (2005). The locations for many of these samples were recorded by Chevron geoscientists on topographic maps (originals now in the USGS Library in Menlo Park, Calif.). The recent availability of digital databases for geologic and topographic maps has provided the opportunity to prepare a database of the locations of these Chevron samples so that the information can be combined with geology and topography for plotting or geospatial analysis. This report provides specific locations for more than 13,000 samples in central California that have enough paleontologic information to determine their age but omits thousands of samples that are too closely spaced to differentiate or those that have only a general location.

  4. An examination of the tripartite model of anxiety and depression in an outpatient sample of adolescents.

    PubMed

    Dia, David A; Harrington, Donna; Silverman, Wendy K

    2010-07-01

    Anxiety and depressive disorders are the most common mental health problems for adolescents; understanding their etiology and course is necessary for developing effective prevention and treatment programs. The tripartite model of anxiety and depression was evaluated in a random, clinical sample of 185 adolescents, with an average age of 15.09 years (SD = 1.9), with 58.4% males (n = 108). Survey packets were mailed to participants (61% response rate). Two models were evaluated: (a) Model one fit adequately, however, modification indices and prior research and theory suggested adding paths between anxiety and depression. (b) Model two tested paths between anxiety and depression; this revised model fit the data well, suggesting a relationship from anxiety to depression. Further, physiological hyperarousal may be a distinct component for anxiety and negative affectivity may be a general risk factor for anxiety and depression in adolescents. The findings that different factors contribute to the cause of anxiety and depression have implications for practice.

  5. Computer modelling of age hardening for cast aluminium alloys

    NASA Astrophysics Data System (ADS)

    Wu, Linda; Ferguson, W. George

    2009-08-01

    Age hardening, or precipitation hardening, is one of the most widely adopted techniques for strengthening of aluminium alloys. Although various age hardening models have been developed for aluminium alloys, from the large volume of literature reviewed, it appears that the bulk of the research has been concentrated on wrought aluminium alloys, only a few of the established precipitation models have been applied to the casting aluminium alloys. In the present work, there are two modelling methods that have been developed and applied to the casting aluminium alloys A356 and A357. One is based on the Shercliff-Ashby methodology to produce a process model, by which we mean a mathematical relationship between process variables (alloy composition, ageing temperature and time) and material properties (yield strength or hardness) through microstructure evolution (precipitate radius, volume fraction). The other method is based on the Kampmann and Wagner Numerical (KWN) model which deals with concomitant nucleation, growth and coarsening and is thus capable of predicting the full evolution of the particle size distribution and then a strength model is used to evaluate the resulting change in hardness or yield strength at room temperature by taking into account contributions from lattice resistance, solid solution hardening and precipitation hardening.

  6. Age of stratospheric air and aging by mixing in global models

    NASA Astrophysics Data System (ADS)

    Garny, Hella; Dietmüller, Simone; Plöger, Felix; Birner, Thomas; Bönisch, Harald; Jöckel, Patrick

    2016-04-01

    The Brewer-Dobson circulation is often quantified by the integrated transport measure age of air (AoA). AoA is affected by all transport processes, including transport along the residual mean mass circulation and two-way mixing. A large spread in the simulation of AoA by current global models exists. Using CCMVal-2 and CCMI-1 global model data, we show that this spread can only in small parts be attributed to differences in the simulated residual circulation. Instead, large differences in the "mixing efficiency" strongly contribute to the differences in the simulated AoA. The "mixing efficiency" is defined as the ratio of the two-way mixing mass flux across the subtropical barrier to the net (residual) mass flux, and this mixing efficiency controls the relative increase in AoA by mixing. We derive the mixing efficiency from global model data using the analytical solution of a simplified version of the tropical leaky pipe (TLP) model, in which vertical diffusion is neglected. Thus, it is assumed that only residual mean transport and horizontal two-way mixing across the subtropical barrier controls AoA. However, in global models vertical mixing and numerical diffusion modify AoA, and these processes likely contribute to the differences in the mixing efficiency between models. We explore the contributions of diffusion and mixing on mean AoA by a) using simulations with the tropical leaky pipe model including vertical diffusion and b) explicit calculations of aging by mixing on resolved scales. Using the TLP model, we show that vertical diffusion leads to a decrease in tropical AoA, i.e. counteracts the increase in tropical mean AoA due to horizontal mixing. Thus, neglecting vertical diffusion leads to an underestimation of the mixing efficiency. With explicit calculations of aging by mixing via integration of daily local mixing tendencies along residual circulation trajectories, we explore the contributions of vertical and horizontal mixing for aging by mixing. The

  7. Is a prostate cancer screening anxiety measure invariant across two different samples of age-appropriate men?

    PubMed Central

    2012-01-01

    Background In order to explore the influence of anxiety on decision–making processes, valid anxiety measures are needed. We evaluated a prostate cancer screening (PCS) anxiety scale that measures anxiety related to the prostate–specific antigen (PSA) test, the digital rectal examination (DRE), and the decision to undergo PCS (PCS-D) using two samples in different settings. Methods We assessed four psychometric properties of the scale using baseline data from a randomized, controlled decision aid trial (n = 301, private clinic; n = 149, public). Results The 3-factor measure had adequate internal consistency reliability, construct validity, and discriminant validity. Confirmatory factor analyses indicated that the 3–factor model did not have adequate fit. When subscales were considered separately, only the 6–item PCS-D anxiety measure had adequate fit and was invariant across clinics. Conclusions Our results support the use of a 6–item PCS-D anxiety measure with age-appropriate men in public and private settings. The development of unique anxiety items relating to the PSA test and DRE is still needed. PMID:22681782

  8. Exploring HP protein models using Wang-Landau sampling

    NASA Astrophysics Data System (ADS)

    Wuest, Thomas; Landau, David P.

    2008-03-01

    The hydrophobic-polar (HP) protein model has become a standard in assessing the efficiency of computational methods for protein structure prediction as well as for exploring the statistical physics of protein folding in general. Numerous methods have been proposed to address the challenges of finding minimal energy conformations within the rough energy landscape of this lattice heteropolymer model. However, only a few studies have been dedicated to the more revealing - but also more demanding - problem of estimating the density of states which allows access to thermodynamic properties of a system at any temperature. Here, we show that Wang-Landau sampling, in connection with a suitable move set (``pull moves''), provides a powerful route for the ground state search and the precise determination of the density of states for HP sequences (with up to 100 monomers) in both, two and three dimensions. Our procedure possesses an intrinsic simplicity and overcomes the inevitable limitations inherent in other more tailored approaches. The main advantage lies in its general applicability to a broad range of lattice protein models that go beyond the scope of the HP model.

  9. Modeling the Orbital Sampling Effect of Extrasolar Moons

    NASA Astrophysics Data System (ADS)

    Heller, René; Hippke, Michael; Jackson, Brian

    2016-04-01

    The orbital sampling effect (OSE) appears in phase-folded transit light curves of extrasolar planets with moons. Analytical OSE models have hitherto neglected stellar limb darkening and non-zero transit impact parameters and assumed that the moon is on a circular, co-planar orbit around the planet. Here, we present an analytical OSE model for eccentric moon orbits, which we implement in a numerical simulator with stellar limb darkening that allows for arbitrary transit impact parameters. We also describe and publicly release a fully numerical OSE simulator (PyOSE) that can model arbitrary inclinations of the transiting moon orbit. Both our analytical solution for the OSE and PyOSE can be used to search for exomoons in long-term stellar light curves such as those by Kepler and the upcoming PLATO mission. Our updated OSE model offers an independent method for the verification of possible future exomoon claims via transit timing variations and transit duration variations. Photometrically quiet K and M dwarf stars are particularly promising targets for an exomoon discovery using the OSE.

  10. Network model of human aging: Frailty limits and information measures

    NASA Astrophysics Data System (ADS)

    Farrell, Spencer G.; Mitnitski, Arnold B.; Rockwood, Kenneth; Rutenberg, Andrew D.

    2016-11-01

    Aging is associated with the accumulation of damage throughout a persons life. Individual health can be assessed by the Frailty Index (FI). The FI is calculated simply as the proportion f of accumulated age-related deficits relative to the total, leading to a theoretical maximum of f ≤1 . Observational studies have generally reported a much more stringent bound, with f ≤fmax<1 . The value of fmax in observational studies appears to be nonuniversal, but fmax≈0.7 is often reported. A previously developed network model of individual aging was unable to recover fmax<1 while retaining the other observed phenomenology of increasing f and mortality rates with age. We have developed a computationally accelerated network model that also allows us to tune the scale-free network exponent α . The network exponent α significantly affects the growth of mortality rates with age. However, we are only able to recover fmax by also introducing a deficit sensitivity parameter 1 -q , which is equivalent to a false-negative rate q . Our value of q =0.3 is comparable to finite sensitivities of age-related deficits with respect to mortality that are often reported in the literature. In light of nonzero q , we use mutual information I to provide a nonparametric measure of the predictive value of the FI with respect to individual mortality. We find that I is only modestly degraded by q <1 , and this degradation is mitigated when increasing number of deficits are included in the FI. We also find that the information spectrum, i.e., the mutual information of individual deficits versus connectivity, has an approximately power-law dependence that depends on the network exponent α . Mutual information I is therefore a useful tool for characterizing the network topology of aging populations.

  11. Rotifers as models for the biology of aging.

    PubMed

    Snell, Terry W

    2014-03-01

    It has been two decades since 1993 when research on the biology of rotifer aging was last reviewed by Enesco. Much has transpired during this time as rotifer biologists have adapted to the "omics" revolution and incorporated these techniques into the experimental analysis of rotifers. Rotifers are amenable to many of these approaches and getting adequate quantities of DNA, RNA, and protein from rotifers is not difficult. Analysis of rotifer genomes, transcriptomes, and proteomes is rapidly yielding candidate genes that likely regulate a variety of features of rotifer biology. Parallel developments in aging biology have recognized the limitations of standard animal models like worms and flies and that comparative aging research has essentially ignored a large fraction of animal phylogeny in the lophotrochozoans. As experimentally tractable members of this group, rotifers have attracted interest as models of aging. In this paper, I review advances over the past 20 years in the biology of aging in rotifers, with emphasis on the unique contributions of rotifer models for understanding aging. The majority of experimental work has manipulated rotifer diet and followed changes in survival and reproductive dynamics like mean lifespan, maximum lifespan, reproductive lifespan, and mortality rate doubling time. The main dietary manipulation has been some form of caloric restriction, withholding food for some period or feeding continuously at low levels. There have been comparative studies of several rotifer species, with some species responding to caloric restriction with life extension, but others not, at least under the tested food regimens. Other aspects of diet are less explored, like nutritional properties of different algae species and their capacity to extend rotifer lifespan. Several descriptive studies have reported many genes involved in rotifer aging by comparing gene expression in young and old individuals. Classes of genes up or down-regulated during aging have

  12. Rotifers as models for the biology of aging

    PubMed Central

    Snell, Terry W.

    2013-01-01

    It has been two decades since 1993 when research on the biology of rotifer aging was last reviewed by Enesco. Much has transpired during this time as rotifer biologists have adapted to the “omics” revolution and incorporated these techniques into the experimental analysis of rotifers. Rotifers are amenable to many of these approaches and getting adequate quantities of DNA, RNA, and protein from rotifers is not difficult. Analysis of rotifer genomes, transcriptomes, and proteomes is rapidly yielding candidate genes that likely regulate a variety of features of rotifer biology. Parallel developments in aging biology have recognized the limitations of standard animal models like worms and flies and that comparative aging research has essentially ignored a large fraction of animal phylogeny in the lophotrochozoans. As experimentally tractable members of this group, rotifers have attracted interest as models of aging. In this paper, I review advances over the past 20 years in the biology of aging in rotifers, with emphasis on the unique contributions of rotifer models for understanding aging. The majority of experimental work has manipulated rotifer diet and followed changes in survival and reproductive dynamics like mean lifespan, maximum lifespan, reproductive lifespan, and mortality rate doubling time. The main dietary manipulation has been some form of caloric restriction, withholding food for some period or feeding continuously at low levels. There have been comparative studies of several rotifer species, with some species responding to caloric restriction with life extension, but others not, at least under the tested food regimens. Other aspects of diet are less explored, like nutritional properties of different algae species and their capacity to extend rotifer lifespan. Several descriptive studies have reported many genes involved in rotifer aging by comparing gene expression in young and old individuals. Classes of genes up or down-regulated during aging

  13. Eating Problems at Age 6 Years in a Whole Population Sample of Extremely Preterm Children

    ERIC Educational Resources Information Center

    Samara, Muthanna; Johnson, Samantha; Lamberts, Koen; Marlow, Neil; Wolke, Dieter

    2010-01-01

    Aim: The aim of this study was to investigate the prevalence of eating problems and their association with neurological and behavioural disabilities and growth among children born extremely preterm (EPC) at age 6 years. Method: A standard questionnaire about eating was completed by parents of 223 children (125 males [56.1%], 98 females [43.9%])…

  14. Transferable Skills Representations in a Portuguese College Sample: Gender, Age, Adaptability and Vocational Development

    ERIC Educational Resources Information Center

    Rocha, Magda

    2012-01-01

    The departing point of this study is the theoretical framework of "Making the Match project" (Evers and Rush in Management Learning 27:275-299, 1996) about how to develop a common language among stakeholders regarding transferable skills. Thus, the paper examines the impact of demographic variables (age and gender) and developmental…

  15. Age Effects of Reported Child Maltreatment in a Canadian Sample of Children and Adolescents

    ERIC Educational Resources Information Center

    Reinke, Diane C.

    2005-01-01

    The general purpose of this study was to examine the proportions of children and adolescents identified with behavioral, emotional and cognitive clinical findings and disabilities. Data from the Canadian Incidence Study of Reported Child Abuse and Neglect (CIS) were used in this study. Participants in this study included 7672 children aged 0 to 15…

  16. Integrated modelling of age and sex patterns of European migration.

    PubMed

    Wiśniowski, Arkadiusz; Forster, Jonathan J; Smith, Peter W F; Bijak, Jakub; Raymer, James

    2016-10-01

    Age and sex patterns of migration are essential for understanding drivers of population change and heterogeneity of migrant groups. We develop a hierarchical Bayesian model to estimate such patterns for international migration in the European Union and European Free Trade Association from 2002 to 2008, which was a period of time when the number of members expanded from 19 to 31 countries. Our model corrects for the inadequacies and inconsistencies in the available data and estimates the missing patterns. The posterior distributions of the age and sex profiles are then combined with a matrix of origin-destination flows, resulting in a synthetic database with measures of uncertainty for migration flows and other model parameters.

  17. Aging, Neurogenesis, and Caloric Restriction in Different Model Organisms

    PubMed Central

    Arslan-Ergul, Ayca; Ozdemir, A Tugrul; Adams, Michelle M

    2013-01-01

    Brain aging is a multifactorial process that is occurring across multiple cognitive domains. A significant complaint that occurs in the elderly is a decrement in learning and memory ability. Both rodents and zebrafish exhibit a similar problem with memory during aging. The neurobiological changes that underlie this cognitive decline are complex and undoubtedly influenced by many factors. Alterations in the birth of new neurons and neuron turnover may contribute to age-related cognitive problems. Caloric restriction is the only non-genetic intervention that reliably increases life span and healthspan across multiple organisms although the molecular mechanisms are not well-understood. Recently the zebrafish has become a popular model organism for understanding the neurobiological consequences but to date very little work has been performed. Similarly, few studies have examined the effects of dietary restriction in zebrafish. Here we review the literature related to memory decline, neurogenesis, and caloric restriction across model organisms and suggest that zebrafish has the potential to be an important animal model for understanding the complex interactions between age, neurobiological changes in the brain, and dietary regimens or their mimetics as interventions. PMID:23936746

  18. [The use of biological age on mental work capacity model in accelerated aging assessment of professional lorry-drivers].

    PubMed

    Bashkireva, A S

    2012-01-01

    The studies of biological age, aging rate, mental work capacity in professional drivers were conducted. The examination revealed peculiarities of system organization of functions determining the mental work capacity levels. Dynamics of the aging process of professional driver's organism in relation with calendar age and driving experience were shown using the biological age model. The results point at the premature decrease of the mental work capacity in professional drivers. It was proved, that premature age-related changes of physiologic and psychophysiologic indices in drivers are just "risk indicators", while long driving experience is a real risk factor, accelerating the aging process. The "risk group" with manifestations of accelerating aging was observed in 40-49-year old drivers with 15-19 years of professional experience. The expediency of using the following methods for the age rate estimation according to biologic age indices and necessity of prophylactic measures for premature and accelerated aging prevention among working population was demonstrated.

  19. Revisiting dark energy models using differential ages of galaxies

    NASA Astrophysics Data System (ADS)

    Rani, Nisha; Jain, Deepak; Mahajan, Shobhit; Mukherjee, Amitabha; Biesiada, Marek

    2017-03-01

    In this work, we use a test based on the differential ages of galaxies for distinguishing the dark energy models. As proposed by Jimenez and Loeb in [1], relative ages of galaxies can be used to put constraints on various cosmological parameters. In the same vein, we reconstruct H0dt/dz and its derivative (H0d2t/dz2) using a model independent technique called non-parametric smoothing. Basically, dt/dz is the change in the age of the object as a function of redshift which is directly linked with the Hubble parameter. Hence for reconstruction of this quantity, we use the most recent H(z) data. Further, we calculate H0dt/dz and its derivative for several models like Phantom, Einstein de Sitter (EdS), ΛCDM, Chevallier-Polarski-Linder (CPL) parametrization, Jassal-Bagla-Padmanabhan (JBP) parametrization and Feng-Shen-Li-Li (FSLL) parametrization. We check the consistency of these models with the results of reconstruction obtained in a model independent way from the data. It is observed that H0dt/dz as a tool is not able to distinguish between the ΛCDM, CPL, JBP and FSLL parametrizations but, as expected, EdS and Phantom models show noticeable deviation from the reconstructed results. Further, the derivative of H0dt/dz for various dark energy models is more sensitive at low redshift. It is found that the FSLL model is not consistent with the reconstructed results, however, the ΛCDM model is in concordance with the 3σ region of the reconstruction at redshift z>= 0.3.

  20. Modelling safety of multistate systems with ageing components

    NASA Astrophysics Data System (ADS)

    Kołowrocki, Krzysztof; Soszyńska-Budny, Joanna

    2016-06-01

    An innovative approach to safety analysis of multistate ageing systems is presented. Basic notions of the ageing multistate systems safety analysis are introduced. The system components and the system multistate safety functions are defined. The mean values and variances of the multistate systems lifetimes in the safety state subsets and the mean values of their lifetimes in the particular safety states are defined. The multi-state system risk function and the moment of exceeding by the system the critical safety state are introduced. Applications of the proposed multistate system safety models to the evaluation and prediction of the safty characteristics of the consecutive "m out of n: F" is presented as well.

  1. Scaling in a Continuous Time Model for Biological Aging

    NASA Astrophysics Data System (ADS)

    de Almeida, R. M. C.; Thomas, G. L.

    In this paper, we consider a generalization to the asexual version of Penna model for biological aging, where we take a continuous time limit. The genotype associated to each individual is an interval of real numbers over which Dirac δ-functions are defined, representing genetically programmed diseases to be switched on at defined ages of the individual life. We discuss two different continuous limits for the evolution equation and two different mutation protocols, to be implemented during reproduction. Exact stationary solutions are obtained and scaling properties are discussed.

  2. Anomalous scaling in an age-dependent branching model.

    PubMed

    Keller-Schmidt, Stephanie; Tuğrul, Murat; Eguíluz, Víctor M; Hernández-García, Emilio; Klemm, Konstantin

    2015-02-01

    We introduce a one-parametric family of tree growth models, in which branching probabilities decrease with branch age τ as τ(-α). Depending on the exponent α, the scaling of tree depth with tree size n displays a transition between the logarithmic scaling of random trees and an algebraic growth. At the transition (α=1) tree depth grows as (logn)(2). This anomalous scaling is in good agreement with the trend observed in evolution of biological species, thus providing a theoretical support for age-dependent speciation and associating it to the occurrence of a critical point.

  3. Estimating child mortality and modelling its age pattern for India.

    PubMed

    Roy, S G

    1989-06-01

    "Using data [for India] on proportions of children dead...estimates of infant and child mortality are...obtained by Sullivan and Trussell modifications of [the] Brass basic method. The estimate of child survivorship function derived after logit smoothing appears to be more reliable than that obtained by the Census Actuary. The age pattern of childhood mortality is suitably modelled by [a] Weibull function defining the probability of surviving from birth to a specified age and involving two parameters of level and shape. A recently developed linearization procedure based on [a] graphical approach is adopted for estimating the parameters of the function."

  4. The revised Temperament and Character Inventory: normative data by sex and age from a Spanish normal randomized sample

    PubMed Central

    Labad, Javier; Martorell, Lourdes; Gaviria, Ana; Bayón, Carmen; Vilella, Elisabet; Cloninger, C. Robert

    2015-01-01

    Objectives. The psychometric properties regarding sex and age for the revised version of the Temperament and Character Inventory (TCI-R) and its derived short version, the Temperament and Character Inventory (TCI-140), were evaluated with a randomized sample from the community. Methods. A randomized sample of 367 normal adult subjects from a Spanish municipality, who were representative of the general population based on sex and age, participated in the current study. Descriptive statistics and internal consistency according to α coefficient were obtained for all of the dimensions and facets. T-tests and univariate analyses of variance, followed by Bonferroni tests, were conducted to compare the distributions of the TCI-R dimension scores by age and sex. Results. On both the TCI-R and TCI-140, women had higher scores for Harm Avoidance, Reward Dependence and Cooperativeness than men, whereas men had higher scores for Persistence. Age correlated negatively with Novelty Seeking, Reward Dependence and Cooperativeness and positively with Harm Avoidance and Self-transcendence. Young subjects between 18 and 35 years had higher scores than older subjects in NS and RD. Subjects between 51 and 77 years scored higher in both HA and ST. The alphas for the dimensions were between 0.74 and 0.87 for the TCI-R and between 0.63 and 0.83 for the TCI-140. Conclusion. Results, which were obtained with a randomized sample, suggest that there are specific distributions of personality traits by sex and age. Overall, both the TCI-R and the abbreviated TCI-140 were reliable in the ‘good-to-excellent’ range. A strength of the current study is the representativeness of the sample. PMID:26713237

  5. The revised Temperament and Character Inventory: normative data by sex and age from a Spanish normal randomized sample.

    PubMed

    Gutierrez-Zotes, Alfonso; Labad, Javier; Martorell, Lourdes; Gaviria, Ana; Bayón, Carmen; Vilella, Elisabet; Cloninger, C Robert

    2015-01-01

    Objectives. The psychometric properties regarding sex and age for the revised version of the Temperament and Character Inventory (TCI-R) and its derived short version, the Temperament and Character Inventory (TCI-140), were evaluated with a randomized sample from the community. Methods. A randomized sample of 367 normal adult subjects from a Spanish municipality, who were representative of the general population based on sex and age, participated in the current study. Descriptive statistics and internal consistency according to α coefficient were obtained for all of the dimensions and facets. T-tests and univariate analyses of variance, followed by Bonferroni tests, were conducted to compare the distributions of the TCI-R dimension scores by age and sex. Results. On both the TCI-R and TCI-140, women had higher scores for Harm Avoidance, Reward Dependence and Cooperativeness than men, whereas men had higher scores for Persistence. Age correlated negatively with Novelty Seeking, Reward Dependence and Cooperativeness and positively with Harm Avoidance and Self-transcendence. Young subjects between 18 and 35 years had higher scores than older subjects in NS and RD. Subjects between 51 and 77 years scored higher in both HA and ST. The alphas for the dimensions were between 0.74 and 0.87 for the TCI-R and between 0.63 and 0.83 for the TCI-140. Conclusion. Results, which were obtained with a randomized sample, suggest that there are specific distributions of personality traits by sex and age. Overall, both the TCI-R and the abbreviated TCI-140 were reliable in the 'good-to-excellent' range. A strength of the current study is the representativeness of the sample.

  6. Spectral ageing in the era of big data: integrated versus resolved models

    NASA Astrophysics Data System (ADS)

    Harwood, Jeremy J.

    2017-04-01

    Continuous injection models of spectral ageing have long been used to determine the age of radio galaxies from their integrated spectrum; however, many questions about their reliability remain unanswered. With various large area surveys imminent (e.g. LOw Frequency ARray, MeerKAT, Murchison Widefield Array) and planning for the next generation of radio interferometers are well underway (e.g. next generation VLA, Square Kilometre Array), investigations of radio galaxy physics are set to shift away from studies of individual sources to the population as a whole. Determining if and how integrated models of spectral ageing can be applied in the era of big data is therefore crucial. In this paper, I compare classical integrated models of spectral ageing to recent well-resolved studies that use modern analysis techniques on small spatial scales to determine their robustness and validity as a source selection method. I find that integrated models are unable to recover key parameters and, even when known a priori, provide a poor, frequency-dependent description of a source's spectrum. I show a disparity of up to a factor of 6 in age between the integrated and resolved methods but suggest, even with these inconsistencies, such models still provide a potential method of candidate selection in the search for remnant radio galaxies and in providing a cleaner selection of high redshift radio galaxies in z - α selected samples.

  7. Validation of transition analysis as a method of adult age estimation in a modern South African sample.

    PubMed

    Jooste, N; L'Abbé, E N; Pretorius, S; Steyn, M

    2016-09-01

    The use of advanced statistical methods, such as transition analysis, has transformed adult age estimation into a systematically and statistically appropriate practice. The method developed by Boldsen and colleagues (2002) uses 36 features from the cranial sutures, pubic symphysis and auricular surface to calculate maximum likelihood point estimates and 95% confidence intervals, using the ADBOU computer software. However, when using the method in a geographically and contextually distinct sample, such as South Africa, accuracy and precision is of concern. This study aimed to test the repeatability, accuracy and precision of the transition analysis method, using the ADBOU computer software, on a South African sample. Age estimations were generated, for 149 black individuals from the Pretoria Bone Collection, using three individual components as well as different combinations of components and prior distributions (uniform and informative). The informative prior distributions represented both an archaeological and a forensic context. Cohen's kappa statistic uncovered some failings in the scoring procedure. While the accuracy compared favourably with existing methods, the method lacked satisfactory precision. Although combining the components improved accuracy and precision, removing the cranium from the combination was beneficial in some instances. The influence of population variation was observed in the scoring procedure, reference sample and the prior distributions. Validity may be improved for a South African sample by adding age-related components that have been developed on a relevant population. A prior distribution based on South African mortality rates might also be beneficial.

  8. Effects of Sample Size, Estimation Methods, and Model Specification on Structural Equation Modeling Fit Indexes.

    ERIC Educational Resources Information Center

    Fan, Xitao; Wang, Lin; Thompson, Bruce

    1999-01-01

    A Monte Carlo simulation study investigated the effects on 10 structural equation modeling fit indexes of sample size, estimation method, and model specification. Some fit indexes did not appear to be comparable, and it was apparent that estimation method strongly influenced almost all fit indexes examined, especially for misspecified models. (SLD)

  9. Influence of ageing on Raman spectra and the conductivity of monolayer graphene samples irradiated by heavy and light ions

    NASA Astrophysics Data System (ADS)

    Butenko, A.; Zion, E.; Kaganovskii, Yu.; Wolfson, L.; Richter, V.; Sharoni, A.; Kogan, E.; Kaveh, M.; Shlimak, I.

    2016-07-01

    The influence of long-term ageing (about one year) on the Raman scattering (RS) spectra and the temperature dependence of conductivity has been studied in two series of monolayer graphene samples irradiated by different doses of C+ and Xe+ ions. It is shown that the main result of ageing consists of changes in the intensity and position of D- and G- and 2D-lines in RS spectra and in an increase of the conductivity. The observed effects are explained in terms of an increase of the radius of the "activated" area around structural defects.

  10. ACTINIDE REMOVAL PROCESS SAMPLE ANALYSIS, CHEMICAL MODELING, AND FILTRATION EVALUATION

    SciTech Connect

    Martino, C.; Herman, D.; Pike, J.; Peters, T.

    2014-06-05

    Filtration within the Actinide Removal Process (ARP) currently limits the throughput in interim salt processing at the Savannah River Site. In this process, batches of salt solution with Monosodium Titanate (MST) sorbent are concentrated by crossflow filtration. The filtrate is subsequently processed to remove cesium in the Modular Caustic Side Solvent Extraction Unit (MCU) followed by disposal in saltstone grout. The concentrated MST slurry is washed and sent to the Defense Waste Processing Facility (DWPF) for vitrification. During recent ARP processing, there has been a degradation of filter performance manifested as the inability to maintain high filtrate flux throughout a multi-batch cycle. The objectives of this effort were to characterize the feed streams, to determine if solids (in addition to MST) are precipitating and causing the degraded performance of the filters, and to assess the particle size and rheological data to address potential filtration impacts. Equilibrium modelling with OLI Analyzer{sup TM} and OLI ESP{sup TM} was performed to determine chemical components at risk of precipitation and to simulate the ARP process. The performance of ARP filtration was evaluated to review potential causes of the observed filter behavior. Task activities for this study included extensive physical and chemical analysis of samples from the Late Wash Pump Tank (LWPT) and the Late Wash Hold Tank (LWHT) within ARP as well as samples of the tank farm feed from Tank 49H. The samples from the LWPT and LWHT were obtained from several stages of processing of Salt Batch 6D, Cycle 6, Batch 16.

  11. Modeling Manufacturing Impacts on Aging and Reliability of Polyurethane Foams

    SciTech Connect

    Rao, Rekha R.; Roberts, Christine Cardinal; Mondy, Lisa Ann; Soehnel, Melissa Marie; Johnson, Kyle; Lorenzo, Henry T.

    2016-10-01

    Polyurethane is a complex multiphase material that evolves from a viscous liquid to a system of percolating bubbles, which are created via a CO2 generating reaction. The continuous phase polymerizes to a solid during the foaming process generating heat. Foams introduced into a mold increase their volume up to tenfold, and the dynamics of the expansion process may lead to voids and will produce gradients in density and degree of polymerization. These inhomogeneities can lead to structural stability issues upon aging. For instance, structural components in weapon systems have been shown to change shape as they age depending on their molding history, which can threaten critical tolerances. The purpose of this project is to develop a Cradle-to-Grave multiphysics model, which allows us to predict the material properties of foam from its birth through aging in the stockpile, where its dimensional stability is important.

  12. Exposure ages and neutron capture record in lunar samples from Fra Mauro.

    NASA Technical Reports Server (NTRS)

    Lugmair, G. W.; Marti, K.

    1972-01-01

    Cosmic-ray exposure ages of Apollo 14 rocks and rock fragments obtained by the Kr81-Kr83 method range from 27 to 700 m.y. Rock 14321, collected near the Cone crater rim, is one of the many approximately 27 m.y. old ejecta which were reported at the Third Lunar Science Conference. All the other rocks have considerably higher exposure ages. Isotopic anomalies from neutron capture in gadolinium, bromine, and barium are used to obtain information on the lunar neutron spectrum at various depths below the lunar surface. The flux ratio of resonance and slow (less than 0.3 eV) neutrons is found to be nearly constant in the topmost approximately 100 g/sq cm.

  13. Defining Predictive Probability Functions for Species Sampling Models.

    PubMed

    Lee, Jaeyong; Quintana, Fernando A; Müller, Peter; Trippa, Lorenzo

    2013-01-01

    We review the class of species sampling models (SSM). In particular, we investigate the relation between the exchangeable partition probability function (EPPF) and the predictive probability function (PPF). It is straightforward to define a PPF from an EPPF, but the converse is not necessarily true. In this paper we introduce the notion of putative PPFs and show novel conditions for a putative PPF to define an EPPF. We show that all possible PPFs in a certain class have to define (unnormalized) probabilities for cluster membership that are linear in cluster size. We give a new necessary and sufficient condition for arbitrary putative PPFs to define an EPPF. Finally, we show posterior inference for a large class of SSMs with a PPF that is not linear in cluster size and discuss a numerical method to derive its PPF.

  14. Impact of aging mechanism on model simulated carbonaceous aerosols

    PubMed Central

    Huang, Y.; Wu, S.; Dubey, M.K.; French, N. H. F.

    2013-01-01

    Carbonaceous aerosols including organic carbon and black carbon have significant implications for both climate and air quality. In the current global climate or chemical transport models, a fixed hydrophobic-to-hydrophilic conversion lifetime for carbonaceous aerosol (τ) is generally assumed, which is usually around one day. We have implemented a new detailed aging scheme for carbonaceous aerosols in a chemical transport model (GEOS-Chem) to account for both the chemical oxidation and the physical condensation-coagulation effects, where τ is affected by local atmospheric environment including atmospheric concentrations of water vapor, ozone, hydroxyl radical and sulfuric acid. The updated τ exhibits large spatial and temporal variations with the global average (up to 11 km altitude) calculated to be 2.6 days. The chemical aging effects are found to be strongest over the tropical regions driven by the low ozone concentrations and high humidity there. The τ resulted from chemical aging generally decreases with altitude due to increases in ozone concentration and decreases in humidity. The condensation-coagulation effects are found to be most important for the high-latitude areas, in particular the polar regions, where the τ values are calculated to be up to 15 days. When both the chemical aging and condensation-coagulation effects are considered, the total atmospheric burdens and global average lifetimes of BC, black carbon, (OC, organic carbon) are calculated to increase by 9% (3%) compared to the control simulation, with considerable enhancements of BC and OC concentrations in the Southern Hemisphere. Model evaluations against data from multiple datasets show that the updated aging scheme improves model simulations of carbonaceous aerosols for some regions, especially for the remote areas in the Northern Hemisphere. The improvement helps explain the persistent low model bias for carbonaceous aerosols in the Northern Hemisphere reported in literature. Further

  15. Rubidium-strontium and potassium-argon age of lunar sample 15555.

    NASA Technical Reports Server (NTRS)

    Murthy, V. R.; Evensen, N. M.; Jahn, B. M.; Coscio, M. R., Jr.

    1972-01-01

    The lunar mare basalt 15555 from the edge of Hadley Rille has been dated at 3.3 b.y. by both rubidium-strontium and potassium-argon techniques. Age and trace element abundances closely resemble those of the Apollo 12 mare basalts. Data from lunar basalts obtained thus far indicate that they cannot be derived by simple fractionation from a homogeneous source.

  16. Genetic mouse models of brain ageing and Alzheimer's disease.

    PubMed

    Bilkei-Gorzo, Andras

    2014-05-01

    Progression of brain ageing is influenced by a complex interaction of genetic and environmental factors. Analysis of genetically modified animals with uniform genetic backgrounds in a standardised, controlled environment enables the dissection of critical determinants of brain ageing on a molecular level. Human and animal studies suggest that increased load of damaged macromolecules, efficacy of DNA maintenance, mitochondrial activity, and cellular stress defences are critical determinants of brain ageing. Surprisingly, mouse lines with genetic impairment of anti-oxidative capacity generally did not show enhanced cognitive ageing but rather an increased sensitivity to oxidative challenge. Mouse lines with impaired mitochondrial activity had critically short life spans or severe and rapidly progressing neurodegeneration. Strains with impaired clearance in damaged macromolecules or defects in the regulation of cellular stress defences showed alterations in the onset and progression of cognitive decline. Importantly, reduced insulin/insulin-like growth factor signalling generally increased life span but impaired cognitive functions revealing a complex interaction between ageing of the brain and of the body. Brain ageing is accompanied by an increased risk of developing Alzheimer's disease. Transgenic mouse models expressing high levels of mutant human amyloid precursor protein showed a number of symptoms and pathophysiological processes typical for early phase of Alzheimer's disease. Generally, therapeutic strategies effective against Alzheimer's disease in humans were also active in the Tg2576, APP23, APP/PS1 and 5xFAD lines, but a large number of false positive findings were also reported. The 3xtg AD model likely has the highest face and construct validity but further studies are needed.

  17. Geophysical Age Dating of Seamounts using Dense Core Flexure Model

    NASA Astrophysics Data System (ADS)

    Hwang, Gyuha; Kim, Seung-Sep

    2016-04-01

    Lithospheric flexure of oceanic plate is thermo-mechanical response of an elastic plate to the given volcanic construct (e.g., seamounts and ocean islands). If the shape and mass of such volcanic loads are known, the flexural response is governed by the thickness of elastic plate, Te. As the age of oceanic plate increases, the elastic thickness of oceanic lithosphere becomes thicker. Thus, we can relate Te with the age of plate at the time of loading. To estimate the amount of the driving force due to seamounts on elastic plate, one needs to approximate their density structure. The most common choice is uniform density model, which utilizes constant density value for a seamount. This approach simplifies computational processes for gravity prediction and error estimates. However, the uniform density model tends to overestimate the total mass of the seamount and hence produces more positive gravitational contributions from the load. Minimization of gravity misfits using uniform density, therefore, favors thinner Te in order to increase negative contributions from the lithospheric flexure, which can compensate for the excessive positives from the seamount. An alternative approach is dense core model, which approximate the heterogeneity nature of seamount density as three bodies of infill sediment, edifice, and dense core. In this study, we apply the dense core model to the Louisville Seamount Chain for constraining flexural deformation. We compare Te estimates with the loading time of the examined seamounts to redefine empirical geophysical age dating of seamounts.

  18. Automatic age and gender classification using supervised appearance model

    NASA Astrophysics Data System (ADS)

    Bukar, Ali Maina; Ugail, Hassan; Connah, David

    2016-11-01

    Age and gender classification are two important problems that recently gained popularity in the research community, due to their wide range of applications. Research has shown that both age and gender information are encoded in the face shape and texture, hence the active appearance model (AAM), a statistical model that captures shape and texture variations, has been one of the most widely used feature extraction techniques for the aforementioned problems. However, AAM suffers from some drawbacks, especially when used for classification. This is primarily because principal component analysis (PCA), which is at the core of the model, works in an unsupervised manner, i.e., PCA dimensionality reduction does not take into account how the predictor variables relate to the response (class labels). Rather, it explores only the underlying structure of the predictor variables, thus, it is no surprise if PCA discards valuable parts of the data that represent discriminatory features. Toward this end, we propose a supervised appearance model (sAM) that improves on AAM by replacing PCA with partial least-squares regression. This feature extraction technique is then used for the problems of age and gender classification. Our experiments show that sAM has better predictive power than the conventional AAM.

  19. Nothobranchius as a model for aging studies. A review

    PubMed Central

    Lucas-Sánchez, Alejandro; Almaida-Pagán, Pedro Francisco; Mendiola, Pilar; de Costa, Jorge

    2014-01-01

    In recent decades, the increase in human longevity has made it increasingly important to expand our knowledge on aging. To accomplish this, the use of animal models is essential, with the most common being mouse (phylogenetically similar to humans, and a model with a long life expectancy) and Caenorhabditis elegans (an invertebrate with a short life span, but quite removed from us in evolutionary terms). However, some sort of model is needed to bridge the differences between those mentioned above, achieving a balance between phylogenetic distance and life span. Fish of the genus Nothobranchius were suggested 10 years ago as a possible alternative for the study of the aging process. In the meantime, numerous studies have been conducted at different levels: behavioral (including the study of the rest-activity rhythm), populational, histochemical, biochemical and genetic, among others, with very positive results. This review compiles what we know about Nothobranchius to date, and examines its future prospects as a true alternative to the classic models for studies on aging. PMID:25110612

  20. A comparative assessment of the Chen et al. and Suchey-Brooks pubic aging methods on a North American sample, .

    PubMed

    Fleischman, Julie M

    2013-03-01

    Accurately estimating the age-at-death of adult human skeletons is fundamental in forensic anthropology. This study evaluates the accuracy of two pubic bone age estimation methods-Chen et al. and Suchey-Brooks. Specimens were obtained from a known collection of modern pubic bones curated at the Maricopa County Forensic Science Center in Phoenix, Arizona. A sample of 296 left male pubic bones of European ancestry was statistically evaluated via bias, absolute mean error, and intra- and inter-observer error. Results indicate that the two methods are similar; the Suchey-Brooks method is the most accurate for aging young adults (error c. 7 years), while the Revised Chen et al. method is most accurate for aging middle-age adults (error c. 6 years). Thus, the Chen et al. method is an important contribution to forensic anthropology for aging older adult skeletal remains. There are, however, some limitations such as subjectivity and the intricate scoring system of Chen et al. method.

  1. Spectral age modelling of the `Sausage' cluster radio relic

    NASA Astrophysics Data System (ADS)

    Stroe, Andra; Harwood, Jeremy J.; Hardcastle, Martin J.; Röttgering, Huub J. A.

    2014-12-01

    CIZA J2242.8+5301 is a post-core passage, binary merging cluster that hosts a large, thin, arc-like radio relic, nicknamed the `Sausage', tracing a relatively strong shock front. We perform spatially resolved spectral fitting to the available radio data for this radio relic, using a variety of spectral ageing models, with the aim of finding a consistent set of parameters for the shock and radio plasma. We determine an injection index of 0.77^{+0.03}_{-0.02} for the relic plasma, significantly steeper than was found before. Standard particle acceleration at the shock front implies a Mach number M=2.90^{+0.10}_{-0.13}, which now matches X-ray measurements. The shock advance speed is vshock ≈ 2500 km s-1, which places the core passage of the two subclusters 0.6-0.8 Gyr ago. We find a systematic spectral age increase from 0 at the northern side of the relic up to ˜60 Myr at ˜145 kpc into the downstream area, assuming a 0.6 nT magnetic field. Under the assumption of freely ageing electrons after acceleration by the `Sausage' shock, the spectral ages are hard to reconcile with the shock speed derived from X-ray and radio observations. Re-acceleration or unusually efficient transport of particle in the downstream area and line-of-sight mixing could help explain the systematically low spectral ages.

  2. Autophagy and ageing: insights from invertebrate model organisms.

    PubMed

    Lionaki, Eirini; Markaki, Maria; Tavernarakis, Nektarios

    2013-01-01

    Ageing in diverse species ranging from yeast to humans is associated with the gradual, lifelong accumulation of molecular and cellular damage. Autophagy, a conserved lysosomal, self-destructive process involved in protein and organelle degradation, plays an essential role in both cellular and whole-animal homeostasis. Accumulating evidence now indicates that autophagic degradation declines with age and this gradual reduction of autophagy might have a causative role in the functional deterioration of biological systems during ageing. Indeed, loss of autophagy gene function significantly influences longevity. Moreover, genetic or pharmacological manipulations that extend lifespan in model organisms often activate autophagy. Interestingly, conserved signalling pathways and environmental factors that regulate ageing, such as the insulin/IGF-1 signalling pathway and oxidative stress response pathways converge on autophagy. In this article, we survey recent findings in invertebrates that contribute to advance our understanding of the molecular links between autophagy and the regulation of ageing. In addition, we consider related mechanisms in other organisms and discuss their similarities and idiosyncratic features in a comparative manner.

  3. Sensitivity and Specificity of Depression Questionnaires in a College-Age Sample

    ERIC Educational Resources Information Center

    Shean, Glenn; Baldwin, Gretchen

    2008-01-01

    The authors evaluated the sensitivity and specificity of the Beck Depression Inventory-II (BDI-II; A. T. Beck, R. A. Steer, & G. K. Brown, 1996) and Center for Epidemiological Studies-Depression Scale (CESD; L. S. Radloff, 1977) questionnaires for a college-student sample. Results indicate that the BDI-II and CES-D evidenced satisfactory…

  4. Monitoring, Modeling, and Diagnosis of Alkali-Silica Reaction in Small Concrete Samples

    SciTech Connect

    Agarwal, Vivek; Cai, Guowei; Gribok, Andrei V.; Mahadevan, Sankaran

    2015-09-01

    Assessment and management of aging concrete structures in nuclear power plants require a more systematic approach than simple reliance on existing code margins of safety. Structural health monitoring of concrete structures aims to understand the current health condition of a structure based on heterogeneous measurements to produce high-confidence actionable information regarding structural integrity that supports operational and maintenance decisions. This report describes alkali-silica reaction (ASR) degradation mechanisms and factors influencing the ASR. A fully coupled thermo-hydro-mechanical-chemical model developed by Saouma and Perotti by taking into consideration the effects of stress on the reaction kinetics and anisotropic volumetric expansion is presented in this report. This model is implemented in the GRIZZLY code based on the Multiphysics Object Oriented Simulation Environment. The implemented model in the GRIZZLY code is randomly used to initiate ASR in a 2D and 3D lattice to study the percolation aspects of concrete. The percolation aspects help determine the transport properties of the material and therefore the durability and service life of concrete. This report summarizes the effort to develop small-size concrete samples with embedded glass to mimic ASR. The concrete samples were treated in water and sodium hydroxide solution at elevated temperature to study how ingress of sodium ions and hydroxide ions at elevated temperature impacts concrete samples embedded with glass. Thermal camera was used to monitor the changes in the concrete sample and results are summarized.

  5. Thermal Response Modeling System for a Mars Sample Return Vehicle

    NASA Technical Reports Server (NTRS)

    Chen, Y.-K.; Miles, Frank S.; Arnold, Jim (Technical Monitor)

    2001-01-01

    A multi-dimensional, coupled thermal response modeling system for analysis of hypersonic entry vehicles is presented. The system consists of a high fidelity Navier-Stokes equation solver (GIANTS), a two-dimensional implicit thermal response, pyrolysis and ablation program (TITAN), and a commercial finite-element thermal and mechanical analysis code (MARC). The simulations performed by this integrated system include hypersonic flowfield, fluid and solid interaction, ablation, shape change, pyrolysis gas eneration and flow, and thermal response of heatshield and structure. The thermal response of the heatshield is simulated using TITAN, and that of the underlying structural is simulated using MARC. The ablating heatshield is treated as an outer boundary condition of the structure, and continuity conditions of temperature and heat flux are imposed at the interface between TITAN and MARC. Aerothermal environments with fluid and solid interaction are predicted by coupling TITAN and GIANTS through surface energy balance equations. With this integrated system, the aerothermal environments for an entry vehicle and the thermal response of the entire vehicle can be obtained simultaneously. Representative computations for a flat-faced arc-jet test model and a proposed Mars sample return capsule are presented and discussed.

  6. Thermal Response Modeling System for a Mars Sample Return Vehicle

    NASA Technical Reports Server (NTRS)

    Chen, Y.-K.; Milos, F. S.

    2002-01-01

    A multi-dimensional, coupled thermal response modeling system for analysis of hypersonic entry vehicles is presented. The system consists of a high fidelity Navier-Stokes equation solver (GIANTS), a two-dimensional implicit thermal response, pyrolysis and ablation program (TITAN), and a commercial finite element thermal and mechanical analysis code (MARC). The simulations performed by this integrated system include hypersonic flowfield, fluid and solid interaction, ablation, shape change, pyrolysis gas generation and flow, and thermal response of heatshield and structure. The thermal response of the heatshield is simulated using TITAN, and that of the underlying structural is simulated using MARC. The ablating heatshield is treated as an outer boundary condition of the structure, and continuity conditions of temperature and heat flux are imposed at the interface between TITAN and MARC. Aerothermal environments with fluid and solid interaction are predicted by coupling TITAN and GIANTS through surface energy balance equations. With this integrated system, the aerothermal environments for an entry vehicle and the thermal response of the entire vehicle can be obtained simultaneously. Representative computations for a flat-faced arc-jet test model and a proposed Mars sample return capsule are presented and discussed.

  7. Openness, neuroticism, conscientiousness, and family health and aging concerns interact in the prediction of health-related Internet searches in a representative U.S. sample

    PubMed Central

    Bogg, Tim; Vo, Phuong T.

    2014-01-01

    Recent estimates suggest 60% of the U.S. adult population uses the Internet to find health-related information. The goal of the present study was to model health-related Internet searches as a function of an interdependent system of personality adaptation in the context of recent health and aging-related concerns. Assessments of background factors, Big Five personality traits, past-month health and aging-related concerns, and the frequency of past-month health-related Internet searches (via Google, Yahoo, AOL, Bing, or some other search engine) were obtained from a representative U.S. sample (N = 1,015). Controlling for background factors, regression analyses showed more frequent health-related Internet searches were predicted by a drive for exploration and investigation (high openness), as well as alarm sensitivity (high openness and high neuroticism) and an anticipatory inclination (high openness and high conscientiousness) in the context of recent problems with aging parents and recent health concerns for a family member. Consistent with interdependent models of personality adaptation, as well as prior evidence for “surrogate” health-related Internet searches, the results suggest a personality process model of search behavior that is partially dependent upon dispositional levels of exploration, emotional stability, control, and health and aging concerns for family members. PMID:24808880

  8. The Mayo Clinic cohort study of personality and aging: design and sampling, reliability and validity of instruments, and baseline description.

    PubMed

    Rocca, Walter A; Grossardt, Brandon R; Peterson, Brett J; Bower, James H; Trenerry, Max R; Ahlskog, J Eric; Sanft, Kevin R; de Andrade, Mariza; Maraganore, Demetrius M

    2006-01-01

    We established a historical cohort of 7,216 subjects who completed the Minnesota Multiphasic Personality Inventory (MMPI) at the Mayo Clinic from 1962 through 1965 for research (not clinical indication), and who resided within a 120-mile radius centered in Rochester, Minnesota. We describe here the overall cohort design and sampling, we report results concerning reliability and validity, and we describe age and sex patterns at baseline for four MMPI scores of primary interest (depression, anxiety, social introversion, and negativity). Subjects excluded from the cohort because of missing data had MMPI scores similar to subjects included (after appropriate rescaling). A cut-off specific for age and sex at the 75th percentile of the distribution of raw scores was valid compared with the traditional clinical cut-off (T scores plus one standard deviation). Baseline scores for all four scales were higher in women than in men at all ages (all p < 0.0001). Depression and social introversion scores showed an increasing trend with age in both sexes (Spearman rank correlation, rho = 0.05 and 0.08, respectively, p < 0.0001 for both). Baseline scores on the anxiety scale showed a decreasing trend with age in both sexes (rho = -0.06, p < 0.0001). Negativity scores remained relatively stable with age in both sexes (rho = 0.03, p = 0.01). We found a high correlation between the anxiety score and the negativity score (rho = 0.90, p < 0.0001) even after the exclusion of overlapping items (rho = 0.68, p < 0.0001). This newly established historical cohort study provides opportunities to test hypotheses regarding the link between personality and aging, aging-related diseases, and overall mortality.

  9. Age at first birth and fathers' subsequent health: evidence from sibling and twin models.

    PubMed

    Pudrovska, Tetyana; Carr, Deborah

    2009-06-01

    Using a sample of 540 siblings and twins from the National Survey of Midlife Development in the United States, this study examines the relationship between the age at which men become biological fathers and their subsequent health. The analysis includes both between-family models that treat brothers as independent observations and within-family models that account for unobserved genetic and early-life environmental endowments shared by brothers within families. Findings indicate that age at first birth has a positive, linear effect on men's health, and this relationship is not explained by the confounding influences of unobserved early-life characteristics. However, the effect of age at first birth on fathers' health is explained by men's socioeconomic and family statuses. Whereas most research linking birth timing to specific diseases focuses narrowly on biological mechanisms among mothers, this study demonstrates the importance of reproductive decisions for men's health and well-being.

  10. An alternative Cattell-Horn-Carroll (CHC) factor structure of the WAIS-IV: age invariance of an alternative model for ages 70-90.

    PubMed

    Niileksela, Christopher R; Reynolds, Matthew R; Kaufman, Alan S

    2013-06-01

    The Wechsler Adult Intelligence Scale--Fourth Edition (WAIS-IV) is by the far the most popular intelligence test for the assessment of adults in clinical and neuropsychological practice. Despite a number of studies examining the factor structure of the WAIS-IV from a Cattell-Horn-Carroll (CHC) perspective (Benson, Hulac, & Kranzler, 2010; Ward, Bergman, & Hebert, 2012), a CHC interpretation of the WAIS-IV for individuals ages 70 and above has been absent from the literature. The exclusion of individuals ages 70 and above in previous research is likely due to the absence of several key supplemental subtests used to create a full CHC model. We provide an alternative five-factor CHC model of the WAIS-IV which includes only the subtests administered to individuals ages 70 and above in the standardization sample. Our results show (a) the alternative CHC model fits the data well; (b) this alternative CHC model met criteria for partial strict measurement invariance across the life span (only Similarities showed noninvariance) using strict criteria; (c) the five factors for ages 70-90 measure the same five CHC broad abilities identified in previous analyses reported for ages 16-69; and (d) the five-factor CHC solution for ages 70-90 is valid for the entire WAIS-IV age range and can be used whenever examiners administer the core battery but opt not to administer supplemental subtests.

  11. Age differences in alcohol drinking patterns among Norwegian and German hospital doctors – a study based on national samples

    PubMed Central

    Rosta, Judith; Aasland, Olaf G.

    2010-01-01

    Aims: To describe and discuss the alcohol drinking patterns of the younger generation of hospital doctors in Norway and Germany – respectively the abstainers, frequent drinkers, episodic heavy drinkers and hazardous drinkers. Methods: Data were collected in nationwide postal surveys among doctors in Norway (2000) and Germany (2006). A representative sample of 1898 German and 602 Norwegian hospital doctors aged 27–65 years were included in the analyses (N=2500). Alcohol drinking patterns were measured using the first three items of AUDIT in Norway and the AUDIT-C in Germany, scores of ≥5 (ranking from 0 to 12) indicating hazardous drinking. Episodic heavy drinking was defined by the intake of ≥60g of ethanol, on one occasion, at least once a week. Frequent drinkers were who drank alcoholic beverages at least twice a week. Abstainers were persons who drank no alcohol. The analyses were performed separately for age groups (27–44 years versus 45–65 years) and genders. Results: Compared to the age groups 45 to 65 years in the Norwegian and German samples, the younger age groups (27–44 years) tend to have higher rates of abstainers, higher rates of infrequent drinking of moderate amount of alcoholic drinks, lower rates of episodic heavy drinking and lower rates of hazardous drinking. Conclusion: The younger generation of hospital doctors in Norway and Germany showed tendencies to healthier drinking habits. Changes in professional life, and in the attitude towards alcohol consumption, may go some way towards explaining these findings. PMID:20200658

  12. Analysis to evaluate predictors of fiberboard aging to guide surveillance sampling for the 9975 life extension program

    SciTech Connect

    Kelly, Elizabeth J.; Daugherty, William L.; Hackney, Elizabeth R.

    2016-05-09

    During surveillance of the 9975 shipping package at the Savannah River Site K-Area Complex, several package dimensions are recorded. The analysis described in this report shows that, based on the current data analysis, two of these measurements, Upper Assembly Outer Diameter (UAOD) and Upper Assembly Inside Height (UAIH), do not have statistically significant aging trends regardless of wattage levels. In contrast, this analysis indicates that the measurement of Air Shield Gap (ASGap) does show a significant increase with age. It appears that the increase is greater for high wattage containers, but this result is dominated by two measurements from high-wattage containers. For all three indicators, additional high-wattage, older containers need to be examined before any definitive conclusions can be reached. In addition, the current analysis indicates that ASGap measurements for low and medium wattage containers are increasing slowly over time. To reduce uncertainties and better capture the aging trend for these containers, additional low and medium wattage older containers should also be examined. Based on this analysis, surveillance guidance is to augment surveillance containers resulting from 3013 surveillance with 9975-focused sampling that targets older, high wattage containers and also includes some older, low and medium wattage containers. This focused sampling began in 2015 and will continue in 2016. The UAOD, UAIH and ASGap data are highly variable. It is possible that additional factors such as seasonal variation and packaging site location might reduce variability and be useful for focusing surveillance and predicting aging.

  13. Annual fish as a genetic model for aging.

    PubMed

    Herrera, Michael; Jagadeeswaran, Pudur

    2004-02-01

    Advancement in the genetics of aging and identification of longevity genes has been largely due to the model organisms such as Caenorhabditis elegans and Drosophila melanogaster. However, knowledge gained from these invertebrates will not be able to identify vertebrate-specific longevity genes. The mouse has a relatively long life span of about 3 years, which limits its utility for screening of longevity genes. Fish have been used in aging studies. However, systematic comparison of survivorship curves for fish is lacking. In this study, we compared the survivorship curves of zebrafish and 2 different annual fish, namely, Cynolebias nigripinnis and Nothobranchius rachovii. These studies established that Nothobranchius rachovii has the shortest life span (8.5 months, at which time 10% of population remains). We also established that it is possible to breed Nothobranchius rachovii under laboratory conditions, and showed that their embryos can be stored for several months and hatched at any time by adding water. In addition, we have isolated 31 cDNA markers out of 71 attempted amplifications based on corresponding homologous genomic sequences in zebrafish and Fugu available from public databases, suggesting that approximately 40% of the genes from Nothobranchius rachovii could be easily isolated. Thus, the ability to be bred under laboratory conditions and the availability of cDNA markers for mapping, along with the major advantage of a relatively short life span, make Nothobranchius rachovii an attractive vertebrate genetic model for aging over other available vertebrate models.

  14. A behavioural dynamic model of the relative age effect.

    PubMed

    Pierson, Kawika; Addona, Vittorio; Yates, Philip

    2014-01-01

    The relationship between date of birth and success in a variety of sports, including hockey, is well established. This phenomenon is known as the relative age effect (RAE). We model the RAE in Canadian youth hockey as a positive feedback loop where an initial age advantage is reinforced through additional training and playing opportunities based on perceived skill superiority. The same causal mechanism leads to a higher quit rate for relatively younger players. Our model effectively replicates the birth month distribution of Canadian National Hockey League players (R2 = 86.79%) when driven by Canadian birth distributions. We use this model to evaluate three policies that aim to lessen the RAE. All of the policies reduce the RAE with a significant delay. The most effective policy is a combination of providing additional support to age disadvantaged children and rotating the cut-off date for youth leagues between January 1st and July 1st annually. In equilibrium, this approach leads to a 96% reduction in the RAE compared to the base case.

  15. Development of sampling efficiency and internal noise in motion detection and discrimination in school-aged children.

    PubMed

    Falkenberg, Helle K; Simpson, William A; Dutton, Gordon N

    2014-07-01

    The aim of this study was to use an equivalent noise paradigm to investigate the development and maturation of motion perception, and how the underlying limitations of sampling efficiency and internal noise effect motion detection and direction discrimination in school-aged children (5-14 years) and adults. Contrast energy thresholds of a 2c/deg sinusoidal grating drifting at 1.0 or 6.0 Hz were measured as a function of added dynamic noise in three tasks: detection of a drifting grating; detection of the sum of two oppositely drifting gratings and direction discrimination of oppositely drifting gratings. Compared to the ideal observer, in both children and adults, the performance for all tasks was limited by reduced sampling efficiency and internal noise. However, the thresholds for discrimination of motion direction and detection of moving gratings show very different developmental profiles. Motion direction discrimination continues to improve after the age of 14 years due to an increase in sampling efficiency that differs with speed. Motion detection and summation were already mature at the age of 5 years, and internal noise was the same for all tasks. These findings were confirmed in a 1-year follow-up study on a group of children from the initial study. The results support suggestions that the detection of a moving pattern and discriminating motion direction are processed by different systems that may develop at different rates.

  16. Age, actuarial risk, and long-term recidivism in a national sample of sex offenders.

    PubMed

    Nicholaichuk, Terry P; Olver, Mark E; Gu, Deqiang; Wong, Stephen C P

    2014-10-01

    Age at release has become an increasing focus of study with regard to evaluating risk in the sex offender population and has been repeatedly shown to be an important component of the risk assessment equation. This study constitutes an extension of a study of sex offender outcomes prepared for the Evaluation Branch, Correctional Service of Canada. The entire cohort of 2,401 male federally incarcerated sexual offenders who reached their warrant expiry date (WED) within 1997/1998, 1998/1999, and 1999/2000 fiscal years were reviewed for the study. Sexual and violent reconviction information was obtained from CPIC criminal records over an average of 12.0 years (SD = 1.7) follow-up. This study focused upon the cohort of sex offenders who were 50 years or older at time of release (N = 542). They were stratified according to risk using a brief actuarial scale (BARS) comprising six binary variables. For the most part, older offenders showed low base rates of sexual recidivism regardless of the risk band into which they fell. The exception was a small group of elderly offenders (n = 20) who fell into the highest risk band, and who showed high levels of sexual recidivism. The results of this combination of cross-sectional and longitudinal analyses of elderly sexual offenders may have important implications for offender management, particularly in light of the increasing numbers of offenders in Canada who fall into the over 50 age cohort.

  17. Early detection of aging cartilage and osteoarthritis in mice and patient samples using atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Stolz, Martin; Gottardi, Riccardo; Raiteri, Roberto; Miot, Sylvie; Martin, Ivan; Imer, Raphaël; Staufer, Urs; Raducanu, Aurelia; Düggelin, Marcel; Baschong, Werner; Daniels, A. U.; Friederich, Niklaus F.; Aszodi, Attila; Aebi, Ueli

    2009-03-01

    The pathological changes in osteoarthritis-a degenerative joint disease prevalent among older people-start at the molecular scale and spread to the higher levels of the architecture of articular cartilage to cause progressive and irreversible structural and functional damage. At present, there are no treatments to cure or attenuate the degradation of cartilage. Early detection and the ability to monitor the progression of osteoarthritis are therefore important for developing effective therapies. Here, we show that indentation-type atomic force microscopy can monitor age-related morphological and biomechanical changes in the hips of normal and osteoarthritic mice. Early damage in the cartilage of osteoarthritic patients undergoing hip or knee replacements could similarly be detected using this method. Changes due to aging and osteoarthritis are clearly depicted at the nanometre scale well before morphological changes can be observed using current diagnostic methods. Indentation-type atomic force microscopy may potentially be developed into a minimally invasive arthroscopic tool to diagnose the early onset of osteoarthritis in situ.

  18. Zebrafish (Danio rerio) as a model for the study of aging and exercise: physical ability and trainability decrease with age.

    PubMed

    Gilbert, Matthew J H; Zerulla, Tanja C; Tierney, Keith B

    2014-02-01

    A rapidly aging global population has motivated the development and use of models for human aging. Studies on aging have shown parallels between zebrafish and humans at the internal organization level; however, few parallels have been studied at the whole-organism level. Furthermore, the effectiveness of exercise as a method to mitigate the effects of aging has not been studied in zebrafish. We investigated the effects of aging and intermittent exercise on swimming performance, kinematics and behavior. Young, middle-aged and old zebrafish (20-29, 36-48 and 60-71% of average lifespan, respectively) were exercised to exhaustion in endurance and sprint swimming tests once a week for four weeks. Both endurance and sprint performance decreased with increased age. Swimming performance improved with exercise training in young and middle-aged zebrafish, but not in old zebrafish. Tail-beat amplitude, which is akin to stride length in humans, increased for all age groups with training. Zebrafish turning frequency, which is an indicator of routine activity, decreased with age but showed no change with exercise. In sum, our results show that zebrafish exhibit a decline in whole-organism performance and trainability with age. These findings closely resemble the senescence-related declines in physical ability experienced by humans and mammalian aging models and therefore support the use of zebrafish as a model for human exercise and aging.

  19. Rb-Sr age of a Luna 16 basalt and the model age of lunar soils.

    NASA Technical Reports Server (NTRS)

    Papanastassiou, D. A.; Wasserburg, G. J.

    1972-01-01

    An internal isochron was determined on a small basalt fragment (sample B-1) returned from the Luna 16 mission, which yields an age of 3.42 plus or minus 0.8 b.y. and a low initial Sr87/Sr86 value. A comparison is made of the data from four lunar missions to mare sites which shows that the last period of major flooding of the mare basins is confined to a narrow time interval of only 0.55 b.y. The direct evidence of major lunar magmatic activity appears to be confined to the interval from 3.1 to 4.0 b.y. The Sr87/Sr86 values for all mare basalts are extremely primitive and lie in a rather narrow range. A diagram is given for initial Sr87/Sr86 as a function of time for all lunar rocks.

  20. Age and growth of chub mackerel ( Xcomber japonicus) in the East China and Yellow Seas using sectioned otolith samples

    NASA Astrophysics Data System (ADS)

    Li, Gang; Chen, Xinjun; Feng, Bo

    2008-11-01

    Although chub mackerel ( Scomber japonicus) is a primary pelagic fish species, we have only limited knowledge on its key life history processes. The present work studied the age and growth of chub mackerel in the East China and Yellow Seas. Age was determined by interpreting and counting growth rings on the sagitta otoliths of 252 adult fish caught by the Chinese commercial purse seine fleet during the period from November 2006 to January 2007 and 150 juveniles from bottom trawl surveys on the spawning ground in May 2006. The difference between the assumed birth date of 1st April and date of capture was used to adjust the age determined from counting the number of complete translucent rings. The parameters of three commonly used growth models, the von Bertalanffy, Logistic and Gompertz models, were estimated using the maximum likelihood method. Based on the Akaike Information Criterion ( AIC), the von Bertalanffy growth model was found to be the most appropriate model. The size-at-age and size-at-maturity values were also found to decrease greatly compared with the results achieved in the 1950s, which was caused by heavy exploitation over the last few decades.

  1. A model for estimating the value of sampling programs and the optimal number of samples for contaminated soil

    NASA Astrophysics Data System (ADS)

    Back, Pär-Erik

    2007-04-01

    A model is presented for estimating the value of information of sampling programs for contaminated soil. The purpose is to calculate the optimal number of samples when the objective is to estimate the mean concentration. A Bayesian risk-cost-benefit decision analysis framework is applied and the approach is design-based. The model explicitly includes sample uncertainty at a complexity level that can be applied to practical contaminated land problems with limited amount of data. Prior information about the contamination level is modelled by probability density functions. The value of information is expressed in monetary terms. The most cost-effective sampling program is the one with the highest expected net value. The model was applied to a contaminated scrap yard in Göteborg, Sweden, contaminated by metals. The optimal number of samples was determined to be in the range of 16-18 for a remediation unit of 100 m2. Sensitivity analysis indicates that the perspective of the decision-maker is important, and that the cost of failure and the future land use are the most important factors to consider. The model can also be applied for other sampling problems, for example, sampling and testing of wastes to meet landfill waste acceptance procedures.

  2. Size separation method for absorption characterization in brown carbon: Application to an aged biomass burning sample

    NASA Astrophysics Data System (ADS)

    Di Lorenzo, Robert A.; Young, Cora J.

    2016-01-01

    The majority of brown carbon (BrC) in atmospheric aerosols is derived from biomass burning (BB) and is primarily composed of extremely low volatility organic carbons. We use two chromatographic methods to compare the contribution of large and small light-absorbing BrC components in aged BB aerosols with UV-vis absorbance detection: (1) size exclusion chromatography (SEC) and (2) reverse phase high-performance liquid chromatography. We observe no evidence of small molecule absorbers. Most BrC absorption arises from large molecular weight components (>1000 amu). This suggests that although small molecules may contribute to BrC absorption near the BB source, analyses of aerosol extracts should use methods selective to large molecular weight compounds because these species may be responsible for long-term BrC absorption. Further characterization with electrospray ionization mass spectrometry (MS) coupled to SEC demonstrates an underestimation of the molecular size determined through MS as compared to SEC.

  3. The age-metallicity relation in the solar neighbourhood from a pilot sample of white dwarf-main sequence binaries

    NASA Astrophysics Data System (ADS)

    Rebassa-Mansergas, A.; Anguiano, B.; García-Berro, E.; Freeman, K. C.; Cojocaru, R.; Manser, C. J.; Pala, A. F.; Gänsicke, B. T.; Liu, X.-W.

    2016-12-01

    The age-metallicity relation (AMR) is a fundamental observational constraint for understanding how the Galactic disc formed and evolved chemically in time. However, there is not yet an agreement on the observational properties of the AMR for the solar neighbourhood, primarily due to the difficulty in obtaining accurate stellar ages for individual field stars. We have started an observational campaign for providing the much needed observational input by using wide white-dwarf-main-sequence (WDMS) binaries. White dwarfs are `natural' clocks and can be used to derive accurate ages. Metallicities can be obtained from the main-sequence companions. Since the progenitors of white dwarfs and the main-sequence stars were born at the same time, WDMS binaries provide a unique opportunity to observationally constrain in a robust way the properties of the AMR. In this work we present the AMR derived from analysing a pilot sample of 23 WDMS binaries and provide clear observational evidence for the lack of correlation between age and metallicity at young and intermediate ages (0-7 Gyr).

  4. Using Modified Sample Entropy to Characterize Aging-Associated Microvascular Dysfunction

    PubMed Central

    Liao, Fuyuan; Jan, Yih-Kuen

    2016-01-01

    Cutaneous microvascular function can be assessed by skin blood flow (SBF) response to thermal stimuli. Usually, the activities of the regulatory mechanisms are quantified by means of spectral analysis of the response. However, spectral measures are unable to characterize the nonlinear dynamics of SBF signal. Sample entropy (SampEn) is a commonly used nonlinear measure of the degree of regularity of time series. However, SampEn value depends on the relationship between the frequency of the studied dynamics and sampling rate. Hence, when time series data are oversampled, SampEn may give misleading results. We modified the definition of SampEn by including a lag between successive data points of the vectors to be compared to address the oversampled issue. The lag could be chosen as the first minimum of the auto mutual information function of the time series. We tested the performance of modified SampEn using simulated signals and SBF data in the young and old groups. The results indicated that modified SampEn yields consistent results for different sampling rates in simulated data, but SampEn cannot. Blood flow data showed a higher degree of regularity during the maximal vasodilation period as compared to the baseline in both groups and a higher degree of regularity in the older group as compared to the young group. Furthermore, our results showed that during the second peak the more regular behavior of blood flow oscillations (BFO) is mainly attributed to enhanced cardiac oscillations. This study suggests that the modified SampEn approach may be useful for assessing microvascular function. PMID:27148065

  5. Age structured dynamical model for an endangered lizard Eulamprus leuraensis

    NASA Astrophysics Data System (ADS)

    Supriatna, A. K.; Rachmadani, Q.; Ilahi, F.; Anggriani, N.; Nuraini, N.

    2014-02-01

    The Blue Mountains Water Skink, Eulamprus leuraensis, is listed as an endangered species under the IUCN Red List. This lizard species has a typical characteristic of growth with a low fecundity. It is known that the offspring quality may decline with maternal age of the parents despite they can grow rapidly from neonatal size to adult size within two to three years. It is also believed that low adult survival rates and specialization on rare and fragmented type of habitat are the main cause leading to the endangered status of the lizard. A mathematical model with age structure for Eulamprus leuraensis, taking into account the variation of survival rate in each structure and the declining of offspring quality with respect to maternal age is considered here. Stable coexistence of non-trivial equilibriumis shown. It is also shown that an endangered status is due to combination oflow reproductive output and low rates of adult survival. Further, understanding the age structure within populations can facilitate efective management of the endangered species.

  6. Effects of sample survey design on the accuracy of classification tree models in species distribution models

    USGS Publications Warehouse

    Edwards, T.C.; Cutler, D.R.; Zimmermann, N.E.; Geiser, L.; Moisen, G.G.

    2006-01-01

    We evaluated the effects of probabilistic (hereafter DESIGN) and non-probabilistic (PURPOSIVE) sample surveys on resultant classification tree models for predicting the presence of four lichen species in the Pacific Northwest, USA. Models derived from both survey forms were assessed using an independent data set (EVALUATION). Measures of accuracy as gauged by resubstitution rates were similar for each lichen species irrespective of the underlying sample survey form. Cross-validation estimates of prediction accuracies were lower than resubstitution accuracies for all species and both design types, and in all cases were closer to the true prediction accuracies based on the EVALUATION data set. We argue that greater emphasis should be placed on calculating and reporting cross-validation accuracy rates rather than simple resubstitution accuracy rates. Evaluation of the DESIGN and PURPOSIVE tree models on the EVALUATION data set shows significantly lower prediction accuracy for the PURPOSIVE tree models relative to the DESIGN models, indicating that non-probabilistic sample surveys may generate models with limited predictive capability. These differences were consistent across all four lichen species, with 11 of the 12 possible species and sample survey type comparisons having significantly lower accuracy rates. Some differences in accuracy were as large as 50%. The classification tree structures also differed considerably both among and within the modelled species, depending on the sample survey form. Overlap in the predictor variables selected by the DESIGN and PURPOSIVE tree models ranged from only 20% to 38%, indicating the classification trees fit the two evaluated survey forms on different sets of predictor variables. The magnitude of these differences in predictor variables throws doubt on ecological interpretation derived from prediction models based on non-probabilistic sample surveys. ?? 2006 Elsevier B.V. All rights reserved.

  7. Evaluating Small Sample Approaches for Model Test Statistics in Structural Equation Modeling

    ERIC Educational Resources Information Center

    Nevitt, Jonathan; Hancock, Gregory R.

    2004-01-01

    Through Monte Carlo simulation, small sample methods for evaluating overall data-model fit in structural equation modeling were explored. Type I error behavior and power were examined using maximum likelihood (ML), Satorra-Bentler scaled and adjusted (SB; Satorra & Bentler, 1988, 1994), residual-based (Browne, 1984), and asymptotically…

  8. Multiple morbidities in companion dogs: a novel model for investigating age-related disease

    PubMed Central

    Jin, Kelly; Hoffman, Jessica M.; Creevy, Kate E.; O’Neill, Dan G.; Promislow, Daniel E.L.

    2016-01-01

    The proportion of men and women surviving over 65 years has been steadily increasing over the last century. In their later years, many of these individuals are afflicted with multiple chronic conditions, placing increasing pressure on healthcare systems. The accumulation of multiple health problems with advanced age is well documented, yet the causes are poorly understood. Animal models have long been employed in attempts to elucidate these complex mechanisms with limited success. Recently, the domestic dog has been proposed as a promising model of human aging for several reasons. Mean lifespan shows twofold variation across dog breeds. In addition, dogs closely share the environments of their owners, and substantial veterinary resources are dedicated to comprehensive diagnosis of conditions in dogs. However, while dogs are therefore useful for studying multimorbidity, little is known about how aging influences the accumulation of multiple concurrent disease conditions across dog breeds. The current study examines how age, body weight, and breed contribute to variation in multimorbidity in over 2,000 companion dogs visiting private veterinary clinics in England. In common with humans, we find that the number of diagnoses increases significantly with age in dogs. However, we find no significant weight or breed effects on morbidity number. This surprising result reveals that while breeds may vary in their average longevity and causes of death, their age-related trajectories of morbidities differ little, suggesting that age of onset of disease may be the source of variation in lifespan across breeds. Future studies with increased sample sizes and longitudinal monitoring may help us discern more breed-specific patterns in morbidity. Overall, the large increase in multimorbidity seen with age in dogs mirrors that seen in humans and lends even more credence to the value of companion dogs as models for human morbidity and mortality. PMID:27876455

  9. Everything under control? The effects of age, gender, and education on trajectories of perceived control in a nationally representative German sample.

    PubMed

    Specht, Jule; Egloff, Boris; Schmukle, Stefan C

    2013-02-01

    Perceived control is an important variable for various demands involved in successful aging. However, perceived control is not set in stone but rather changes throughout the life course. The aim of this study was to identify cross-sectional age differences and longitudinal mean-level changes as well as rank-order changes in perceived control with respect to gender and education. Furthermore, changes in income and health were analyzed to explain trajectories of perceived control. In a large and representative sample of Germans across all of adulthood, 9,484 individuals gave information about their perceived control twice over a period of 6 years. Using locally weighted smoothing (LOESS) curves and latent structural equation modeling, four main findings were revealed: (a) Perceived control increased until ages 30-40, then decreased until about age 60, and increased slightly afterwards. (b) The rank order of individuals in perceived control was relatively unstable, especially in young adulthood, and reached a plateau at about age 40. (c) Men perceived that they had more control than did women, but there were no gender differences in the development of perceived control. (d) Individuals with more education perceived that they had more control than those with less education, and there were slight differences in the development of perceived control dependent on education. Taken together, these findings offer important insights into the development of perceived control across the life span.

  10. Marital happiness and sleep disturbances in a multi-ethnic sample of middle-aged women.

    PubMed

    Troxel, Wendy M; Buysse, Daniel J; Hall, Martica; Matthews, Karen A

    2009-01-01

    Previous research suggests that divorced individuals, particularly women, have higher rates of sleep disturbances as compared to married individuals. Among the married, however, little is known about the association between relationship quality and sleep. The present study examined the association between marital happiness and self-reported sleep disturbances in a sample of midlife women drawn from the Study of Women's Health Across the Nation (SWAN), a multi-site, multi-ethnic, community-based study (N = 2,148). Marital happiness was measured using a single item from the Dyadic Adjustment Scale, and sleep disturbance was assessed using 4 items from the Women's Health Initiative Insomnia Rating Scale (WHIIRS). After controlling for relevant covariates, maritally happy women reported fewer sleep disturbances, with the association evident among Caucasian women and to a lesser extent among African American women.

  11. 3HE RECOVERY FROM A TRITIUM-AGED LANA75 SAMPLE

    SciTech Connect

    Shanahan, K.

    2010-12-01

    {sup 3}He recovery is a topic of recent interest. One potential recovery source is from metal hydride materials once used to store tritium, as the decay product, {sup 3}He, is primarily trapped in the metal lattice, usually in bubbles, with such materials. In 2001, a Tritium Exposure Program (TEP) sample known as LANA75-SP1 was retired and the material was removed from the test cell and stored. Subsequently scoping temperature programmed desorption (TPD) experiments were conducted on that material to see what it might take to drive out He and residual H isotopes (the heel). Two experiments consisted of heating the sample in the presence of an excess of tin (the so-called Sn fusion experiment), and one was a simple TPD with no additives. Prior data on the so-called '21-month bed' material in the 1980's had produced {approx}21 cc of gas per gram of a LANA30 material (LaNi4.7Al0.3), with approximately 67% of that being {sup 3}He and the rest being D{sub 2} (Fig.3). However, the material had to be heated in excess of 850 C to obtain that level. Heating to less produced approximately half that amount of gas. The data also showed that {sup 3}He was released at different temperatures than the residual hydrogen isotopes. Unfortunately this implies full {sup 3}He recovery will be a difficult process. Therefore, it seemed advisable to attempt to extract as much information from the 3 scoping experiments from 2001-2 as possible.

  12. Re-evaluating neonatal-age models for ungulates: does model choice affect survival estimates?

    PubMed

    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

  13. Re-Evaluating Neonatal-Age Models for Ungulates: Does Model Choice Affect Survival Estimates?

    PubMed Central

    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

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

    USGS Publications Warehouse

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

    2014-01-01

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

  15. Chronic depression as a model disease for cerebral aging.

    PubMed

    Bewernick, Bettina H; Schlaepfer, Thomas E

    2013-03-01

    Conceptualizations of the underlying neurobiology of major depression have changed their focus from dysfunctions of neurotransmission to dysfunctions of neurogenesis and neuroprotection. The "neurogenesis hypothesis of depression" posits that changes in the rate of neurogenesis are the underlying mechanism in the pathology and treatment of major depression. Stress, neuroinflammation, dysfunctional insulin regulation, oxidative stress, and alterations in neurotrophic factors possibly contribute to the development of depression. The influence of antidepressant therapies, namely pharmacotherapy and neuroprotectants, on cellular plasticity are summarized. A dysfunction of complex neuronal networks as a consequence of neural degeneration in neuropsychiatric diseases has led to the application of deep brain stimulation. We discuss the way depression seen in the light of the neurogenesis hypothesis can be used as a model disease for cerebral aging. A common pathological mechanism in depression and cerebral aging-a dysfunction of neuroprotection and neurogenesis-is discussed. This has implications for new treatment methods.

  16. Aging

    PubMed Central

    Park, Dong Choon

    2013-01-01

    Aging is initiated based on genetic and environmental factors that operate from the time of birth of organisms. Aging induces physiological phenomena such as reduction of cell counts, deterioration of tissue proteins, tissue atrophy, a decrease of the metabolic rate, reduction of body fluids, and calcium metabolism abnormalities, with final progression onto pathological aging. Despite the efforts from many researchers, the progression and the mechanisms of aging are not clearly understood yet. Therefore, the authors would like to introduce several theories which have gained attentions among the published theories up to date; genetic program theory, wear-and-tear theory, telomere theory, endocrine theory, DNA damage hypothesis, error catastrophe theory, the rate of living theory, mitochondrial theory, and free radical theory. Although there have been many studies that have tried to prevent aging and prolong life, here we introduce a couple of theories which have been proven more or less; food, exercise, and diet restriction. PMID:24653904

  17. AGING PERFORMANCE OF MODEL 9975 PACKAGE FLUOROELASTOMER O-RINGS

    SciTech Connect

    Hoffman, E.; Daugherty, W.; Skidmore, E.; Dunn, K.; Fisher, D.

    2011-05-31

    The influence of temperature and radiation on Viton{reg_sign} GLT and GLT-S fluoroelastomer O-rings is an ongoing research focus at the Savannah River National Laboratory. The O-rings are credited for leaktight containment in the Model 9975 shipping package used for transportation of plutonium-bearing materials. At the Savannah River Site, the Model 9975 packages are being used for interim storage. Primary research efforts have focused on surveillance of O-rings from actual packages, leak testing of seals at bounding aging conditions and the effect of aging temperature on compression stress relaxation behavior, with the goal of service life prediction for long-term storage conditions. Recently, an additional effort to evaluate the effect of aging temperature on the oxidation of the materials has begun. Degradation in the mechanical properties of elastomers is directly related to the oxidation of the polymer. Sensitive measurements of the oxidation rate can be performed in a more timely manner than waiting for a measurable change in mechanical properties, especially at service temperatures. Measuring the oxidation rate therefore provides a means to validate the assumption that the degradation mechanisms(s) do not change from the elevated temperatures used for accelerated aging and the lower service temperatures. Monitoring the amount of oxygen uptake by the material over time at various temperatures can provide increased confidence in lifetime predictions. Preliminary oxygen consumption analysis of a Viton GLT-based fluoroelastomer compound (Parker V0835-75) using an Oxzilla II differential oxygen analyzer in the temperature range of 40-120 C was performed. Early data suggests oxygen consumption rates may level off within the first 100,000 hours (10-12 years) at 40 C and that sharp changes in the degradation mechanism (stress-relaxation) are not expected over the temperature range examined. This is consistent with the known long-term heat aging resistance of

  18. Chronic neck and shoulder pain, age, and working conditions: longitudinal results from a large random sample in France

    PubMed Central

    Cassou, B; Derriennic, F; Monfort, C; Norton, J; Touranchet, A

    2002-01-01

    Aims: To analyse the effects of age and occupational factors on both the incidence and the disappearance of chronic neck and shoulder pain after a five year follow up period. Methods: A prospective longitudinal investigation (ESTEV) was carried out in 1990 and 1995 in seven regions of France. A random sample of male and female workers born in 1938, 1943, 1948, and 1953 was selected from the occupational physicians' files. In 1990, 21 378 subjects were interviewed (88% of those contacted), and 87% were interviewed again in 1995. Chronic neck and shoulder pain satisfying specific criteria, and psychosocial working conditions were investigated by a structured self administered questionnaire and a clinical examination. Results: Prevalence (men 7.8%, women 14.8% in 1990) and incidence (men 7.3%, women 12.5% for the period 1990–95) of chronic neck and shoulder pain increased with age, and were more frequent among women than men in every birth cohort. The disappearance rate of chronic neck and shoulder pain decreased with age. Some adverse working conditions (repetitive work under time constraints, awkward work for men, repetitive work for women) contributed to the development of these disorders, independently of age. Psychosocial factors seemed to play a role in both the development and disappearance of chronic neck and shoulder pain. Data did not show specific interactions between age and working conditions. Conclusions: The aging of the workforce appears to contribute to the widespread concern about chronic neck and shoulder pain. A better understanding of work activity regulation of older workers can open up new preventive prospects. PMID:12151610

  19. Improved age modelling approaches as exemplified by the revised chronology for the Central European varved lake Soppensee

    NASA Astrophysics Data System (ADS)

    Blockley, S. P. E.; Ramsey, C. Bronk; Lane, C. S.; Lotter, A. F.

    2008-01-01

    One of the key factors in understanding past climate change is the development of robust age models that have sufficient chronological precision for comparing different palaeoclimate archives, while retaining accuracy. Recent developments in Bayesian age modelling are applied here to the Swiss varve lake, Soppensee. We develop revised age models for this sequence using the available stratigraphic information to constrain the calibrated radiocarbon ages. We begin by using stratigraphical order as the only constraint and then sequentially increase the information incorporated into the model, using relative varve age, sample depth, and varying depositional models. Within this Bayesian framework, we develop internally robust models that significantly improve the dating precision and are applicable to both varved and non-varved sequences. We then compare the model output to wider chronological information, such as the age of the Laacher See Tephra in order to test the model accuracy. The results of this exercise suggest that these methods can be used to build very reliable improved age models in a variety of records.

  20. Corn blight review: Sampling model and ground data measurements program

    NASA Technical Reports Server (NTRS)

    Allen, R. D.

    1972-01-01

    The sampling plan involved the selection of the study area, determination of the flightline and segment sample design within the study area, and determination of a field sample design. Initial interview survey data consisting of crop species acreage and land use were collected. On all corn fields, additional information such as seed type, row direction, population, planting date, ect. were also collected. From this information, sample corn fields were selected to be observed through the growing season on a biweekly basis by county extension personnel.

  1. Monte Carlo path sampling approach to modeling aeolian sediment transport

    NASA Astrophysics Data System (ADS)

    Hardin, E. J.; Mitasova, H.; Mitas, L.

    2011-12-01

    Coastal communities and vital infrastructure are subject to coastal hazards including storm surge and hurricanes. Coastal dunes offer protection by acting as natural barriers from waves and storm surge. During storms, these landforms and their protective function can erode; however, they can also erode even in the absence of storms due to daily wind and waves. Costly and often controversial beach nourishment and coastal construction projects are common erosion mitigation practices. With a more complete understanding of coastal morphology, the efficacy and consequences of anthropogenic activities could be better predicted. Currently, the research on coastal landscape evolution is focused on waves and storm surge, while only limited effort is devoted to understanding aeolian forces. Aeolian transport occurs when the wind supplies a shear stress that exceeds a critical value, consequently ejecting sand grains into the air. If the grains are too heavy to be suspended, they fall back to the grain bed where the collision ejects more grains. This is called saltation and is the salient process by which sand mass is transported. The shear stress required to dislodge grains is related to turbulent air speed. Subsequently, as sand mass is injected into the air, the wind loses speed along with its ability to eject more grains. In this way, the flux of saltating grains is itself influenced by the flux of saltating grains and aeolian transport becomes nonlinear. Aeolian sediment transport is difficult to study experimentally for reasons arising from the orders of magnitude difference between grain size and dune size. It is difficult to study theoretically because aeolian transport is highly nonlinear especially over complex landscapes. Current computational approaches have limitations as well; single grain models are mathematically simple but are computationally intractable even with modern computing power whereas cellular automota-based approaches are computationally efficient

  2. Two-dimensional sample entropy analysis of rat sural nerve aging.

    PubMed

    da Silva, Luiz Eduardo Virgilio; Senra Filho, Antonio Carlos da Silva; Fazan, Valeria Paula Sassoli; Felipe, Joaquim Cezar; Murta, Luiz Otavio

    2014-01-01

    Entropy analysis of images are usually performed using Shannon entropy, which calculates the probability of occurrency of each gray level on the image. However, not only the pixel gray level but also the spatial distribution of pixels might be important for image analysis. On the other hand, sample entropy (SampEn) is an important tool for estimation of irregularity in time series, which calculates the probability of pattern occurrence within the series. Therefore, we propose here an extension of SampEn to a two-dimensional case, namely SampEn2D, as an entropy method for extracting features from images that accounts for the spatial distribution of pixels. SampEn2D was applied to histological segments of sural nerve obtained from young (30 days) and elderly (720 days) rats. Morphometric indexes, such as the total number of myelinated fibers and the average myelinated fibers area and perimeter were also calculated. Results show that SampEn2D can extract useful information from histological nerve images, classifying elderly rat image as more regular than young rat. As SampEn2D is related to irregularity/unpredictability, we can conclude that the proposed method is complementary to morphometric indexes. Further studies are being built to validate SampEn2D.

  3. Cognitive aging and hearing acuity: modeling spoken language comprehension

    PubMed Central

    Wingfield, Arthur; Amichetti, Nicole M.; Lash, Amanda

    2015-01-01

    The comprehension of spoken language has been characterized by a number of “local” theories that have focused on specific aspects of the task: models of word recognition, models of selective attention, accounts of thematic role assignment at the sentence level, and so forth. The ease of language understanding (ELU) model (Rönnberg et al., 2013) stands as one of the few attempts to offer a fully encompassing framework for language understanding. In this paper we discuss interactions between perceptual, linguistic, and cognitive factors in spoken language understanding. Central to our presentation is an examination of aspects of the ELU model that apply especially to spoken language comprehension in adult aging, where speed of processing, working memory capacity, and hearing acuity are often compromised. We discuss, in relation to the ELU model, conceptions of working memory and its capacity limitations, the use of linguistic context to aid in speech recognition and the importance of inhibitory control, and language comprehension at the sentence level. Throughout this paper we offer a constructive look at the ELU model; where it is strong and where there are gaps to be filled. PMID:26124724

  4. Monitoring and Modeling the Fluctuations in Apparent Groundwater Age During a 30-Day Pumping Test.

    NASA Astrophysics Data System (ADS)

    Perle, M. E.; Zhang, Y.; Fogg, G. E.

    2004-12-01

    Recent research shows that dispersion due to geologic heterogeneity can cause large (10's to 100's of yrs) variations in actual groundwater age within individual samples drawn from a well, even if well bore mixing is not significant. We hypothesize that the presence of such large ranges in groundwater age may cause the mean apparent age as estimated from environmental tracers such as CFC's, SF&_{6}, and ^{3}H-^{3}He to drift measurably during long-term, continuous pumping. This hypothesis was confirmed by 3-D numerical experiments wherein variation in groundwater ages under high-rate (\\sim0.06 m^{3}/s; 1,000 gpm) long-term pumping was modeled using backward-time random walk particle tracking techniques combined with geostatistical simulations of hydrofacies heterogeneity. Results indicate that the age distribution within a water sample and the mean apparent age implied by environmental tracers is strongly influenced by historical atmospheric concentrations of environmental tracers and subsurface heterogeneity. As a partial implementation of this same experiment in the field, an abandoned well was pumped at a low rate (\\sim0.005 m^{3}/s; 75 gpm) during 53 days. Water samples were collected from the top and bottom of a 25 foot well screen at 12 hour intervals for the first 30 days and were analyzed for CFC's, SF&6, and 3H-3He. The measured tracer ages indicate that 1) CFC-11 apparent ages increased with time within the first five days of pumping and then remained constant for the remainder of the pump test; 2) trends in CFC-12, CFC-113 and SF&_{6}$ indicate a discrepancy in apparent ages with CFC-11, 3) water reaching the top interval is younger than water reaching the bottom interval. Gas samples were collected from the unsaturated zone to investigate possible CFC contamination and tracer concentration spatial variations in the pumping well recharge zone. Potential effects of heterogeneity and local CFC contamination on the monitoring results will be discussed.

  5. The OMS3 JGrass-NewAge Environmental Modelling System

    NASA Astrophysics Data System (ADS)

    Formetta, G.; David, O.; Rigon, R.

    2012-12-01

    The need for integrated analysis, and the multiplicity of possible goals in analyses that require hydro-biophysical modelling, necessitates more than ever the capability of composing modelling solutions with parts of known quality, which are transparent to users and consist of reusable model components. Moreover, modern hydrological modelling requires interaction with GIS tools to allow visualizations and the data-processing necessary to synthesise knowledge from high volumes of inputs and outputs data. Last but not least, doing science that is reproducible has requirements that go beyond the computational issues to embrace the possibility to inspection the tools, and easy compare modelling solutions by third party groups. The JGrass-NewAge system was born in order to satisfy these requirements. It is based on the geographic information system uDig-JGrass, and is composed of two parts: (i) the system of visualization of the data and of the results based on uDig; (ii) the modelling components. The latter are implemented as OMS3 components which can be connected or excluded at runtime, according to the needs and works seamlessly inside the uDig Spatial Toolbox. The system is based on a hillslope-link geometrical partition of the landscape, thus the basic unit, where the water budget is evaluated, is the hillslope, and each one of them drains into a single associated link rather than cells or pixels. To this conceptual partition corresponds an implementation of informatics that uses vectorial features for channels, and raster data for hillslopes. The mass budget for each hillslope can be performed in two ways: according to a modification of Duffy dynamical model of hillslope runoff or according to HyMod lumped model. Differently from traditional rainfall-runoff models where the discharge is usually given at the outlet of a catchment, the discharge is evaluated in each link of the river network according to a procedure presented in Cuencas model. The system includes

  6. Age-structured mark-recapture analysis: A virtual-population-analysis-based model for analyzing age-structured capture-recapture data

    USGS Publications Warehouse

    Coggins, L.G.; Pine, William E.; Walters, C.J.; Martell, S.J.D.

    2006-01-01

    We present a new model to estimate capture probabilities, survival, abundance, and recruitment using traditional Jolly-Seber capture-recapture methods within a standard fisheries virtual population analysis framework. This approach compares the numbers of marked and unmarked fish at age captured in each year of sampling with predictions based on estimated vulnerabilities and abundance in a likelihood function. Recruitment to the earliest age at which fish can be tagged is estimated by using a virtual population analysis method to back-calculate the expected numbers of unmarked fish at risk of capture. By using information from both marked and unmarked animals in a standard fisheries age structure framework, this approach is well suited to the sparse data situations common in long-term capture-recapture programs with variable sampling effort. ?? Copyright by the American Fisheries Society 2006.

  7. Aging and associative recognition: A view from the DRYAD model of age-related memory deficits.

    PubMed

    Benjamin, Aaron S

    2016-02-01

    How do we best characterize the memory deficits that accompany aging? A popular hypothesis, articulated originally by Naveh-Benjamin (2000) and reviewed in the accompanying article by Smyth and Naveh-Benjamin (2016), suggests that older adults are selectively deficient in establishing associations between to-be-learned memoranda and as a result have deficits in memory for sources or contexts. An alternative proposal, called density of representations yields age-related deficits (DRYAD) and outlined in recent articles by Benjamin (2010) and colleagues (Benjamin, Diaz, Matzen, & Johnson, 2012), attributes disproportionate deficits in memory to a global, rather than a selective, deficit of memory. In an attempt to adjudicate between these competing positions, Smyth and Naveh-Benjamin (2016) discussed 2 sets of experimental data that they claim speak against the global deficit model. Here I review some general principles of how the global-deficit view is applied to experimental paradigms and demonstrate that even a simplified form of DRYAD can comfortably accommodate the critical findings cited by Smyth and Naveh-Benjamin. I also evaluate aspects of their results that may be problematic for DRYAD and describe ways in which DRYAD's account of associative recognition can be falsified. I end with a discussion of the complementary strengths and weaknesses of the 2 approaches and consider ways in which the associative deficit hypothesis and DRYAD might work more profitably together than apart.

  8. Preparation of NO2-Aged Silver-Functionalized Silica-Aerogel and Silver Mordenite Samples

    SciTech Connect

    Jordan, Jacob A.; Bruffey, Stephanie H.

    2016-10-01

    Reprocessing used nuclear fuel can result in the volatilization of radioactive gaseous species, including 129I, into the various process off-gas streams. In order to comply with US regulatory requirements, plant off-gas streams must be treated to remove the iodine prior to discharging the off-gas into the environment. The performance of available gas removal methods depends not only on the concentration of the volatile radioisotope of interest, but also on other constituents that could be present in the reprocessing off-gas streams. Some of the constituents, such as NOx produced during fuel dissolution, are known to have deleterious effects on the capture performance of silver-based sorbents used for iodine removal. Commercially available reduced silver mordenite (AgZ) has an iodine saturation concentration of 7.0-9.0 wt%, and its iodine sorption capacity is reduced by 20-50% as a result of NO2 aging. Silverfunctionalized silica aerogel (AgAerogel), an alternative for iodine capture, has an initial iodine saturation of 29.0 wt% and its iodine capacity is only reduced by 15% from NO2 aging. Understanding the differences in aging behavior between AgZ and AgAerogel is critical to determining the behavior of these sorbents under realistic off-gas conditions. To assist in future technical studies on this topic, samples of both AgZ and AgAerogel were aged with NO2. In the experiment, 10.2190 g of AgZ and 10.1771 g of AgAerogel were exposed to a static 0.75% NO2/dry air blend for a period of 28 days. The samples were then removed and stored under argon until needed for future experiments.=

  9. The memory screening outreach program: findings from a large community-based sample of middle-aged and older adults.

    PubMed

    Crews, W David; Harrison, David W; Keiser, Alison M; Kunze, Culvette M

    2009-09-01

    Few papers have been published concerning the efficacy of community-based memory and dementia screening programs. This article examines the descriptive, clinical, and outcome characteristics of participants attending the Memory Screening Outreach Program (MSOP). The program provided free screenings of participants' short-term memory processes, neurocognitive complaints, and depressive and psychiatric symptomatology. Screening results were subsequently forwarded to participants and their designated healthcare providers (HCPs), and approximately 8 weeks later, participants who received follow-up recommendations were mailed a survey assessing screening-related outcomes. One thousand community-based persons aged 44 to 91 participated in the program at 16 screening sites. Results indicated that 44.3% of the MSOP participants received follow-up recommendations secondary to age-inappropriate memory impairments, depressive or psychiatric symptomatology, significant neurocognitive complaints, need for respite, or a combination thereof. Memory impairments and depressive or psychiatric symptomatology contributed, at least in part, to the recommendations of 24.0% and 30.9% of the sample, respectively. The prevalence of impaired Wechsler Memory Scale-III subtest performances ranged from 20.5% to 5.4%, and 28.7% of the participants exhibited elevated depression inventory scores. Of the participants who returned follow-up surveys, 49.5% visited their primary HCPs regarding their screening results; of the participants who had not followed up, 36.8% indicated plans to do so. Of the participants who followed up, contributing conditions and diagnoses were identified in 50.9%, medication or supplement recommendations or regimen changes were provided to 47.1%, and 17.0% were referred to healthcare specialists. Overall, the MSOP proved efficacious in identifying age-inappropriate memory impairments, notable depressive and psychiatric symptomatology, and significant neurocognitive

  10. Sample Size Considerations in Prevention Research Applications of Multilevel Modeling and Structural Equation Modeling.

    PubMed

    Hoyle, Rick H; Gottfredson, Nisha C

    2015-10-01

    When the goal of prevention research is to capture in statistical models some measure of the dynamic complexity in structures and processes implicated in problem behavior and its prevention, approaches such as multilevel modeling (MLM) and structural equation modeling (SEM) are indicated. Yet the assumptions that must be satisfied if these approaches are to be used responsibly raise concerns regarding their use in prevention research involving smaller samples. In this article, we discuss in nontechnical terms the role of sample size in MLM and SEM and present findings from the latest simulation work on the performance of each approach at sample sizes typical of prevention research. For each statistical approach, we draw from extant simulation studies to establish lower bounds for sample size (e.g., MLM can be applied with as few as ten groups comprising ten members with normally distributed data, restricted maximum likelihood estimation, and a focus on fixed effects; sample sizes as small as N = 50 can produce reliable SEM results with normally distributed data and at least three reliable indicators per factor) and suggest strategies for making the best use of the modeling approach when N is near the lower bound.

  11. Sample Size Considerations in Prevention Research Applications of Multilevel Modeling and Structural Equation Modeling

    PubMed Central

    Hoyle, Rick H.; Gottfredson, Nisha C.

    2014-01-01

    When the goal of prevention research is to capture in statistical models some measure of the dynamic complexity in structures and processes implicated in problem behavior and its prevention, approaches such as multilevel modeling (MLM) and structural equation modeling (SEM) are indicated. Yet the assumptions that must be satisfied if these approaches are to be used responsibly raise concerns regarding their use in prevention research involving smaller samples. In this manuscript we discuss in nontechnical terms the role of sample size in MLM and SEM and present findings from the latest simulation work on the performance of each approach at sample sizes typical of prevention research. For each statistical approach, we draw from extant simulation studies to establish lower bounds for sample size (e.g., MLM can be applied with as few as 10 groups comprising 10 members with normally distributed data, restricted maximum likelihood estimation, and a focus on fixed effects; sample sizes as small as N = 50 can produce reliable SEM results with normally distributed data and at least three reliable indicators per factor) and suggest strategies for making the best use of the modeling approach when N is near the lower bound. PMID:24752569

  12. Changes in Volatile Compounds during Aging of Sweet Fennel Fruits-Comparison of Hydrodistillation and Static Headspace Sampling Methods.

    PubMed

    Najdoska-Bogdanov, Mence; Bogdanov, Jane B; Stefova, Marina

    2016-03-01

    Two extraction methods for subsequent gas chromatographic (GC) determination of volatiles from freshly harvested and aged fennel fruit samples (Foeniculum vulgare Mill.,ssp. vulgare var. dulce) have been compared. Hydrodistillation followed by GC-FID and GC-MS analysis was used as a standard method for essential oil characterization, while static headspace followed by GC (SHS-GC-FID) was used as a comparative method for determination of volatile components. As the fennel fruit ages, there is a gradual loss of the volatile components as indicated by the lower yield of essential oil and lower content of volatiles, as indicated by the alternative SHS-GC-FID analysis. Slight differences observed for the main components (trans-anethole, estragole, fenchone, and limonene) using the two methods are negligible, indicating that these volatiles did not undergo chemical transformation during the sample preparation procedures. A difference in anisaldehyde content was observed when the composition of the hydrodistilled essential oil was compared with the SHS-GC-FIDanalysis of volatiles and explanation for the variation of anisaldehyde content and the origin of other compounds was suggested. Comparison of the obtained results showed that limonene oxides, carvone and carveolare detectable in SHS-GC-FID analysis of the aged fennel fruits, while in hydrodistilled samples analyzed by GC-FID they were not present. Another observed difference was the appearance of products in significant amounts with higher retention times than trans-anethole, namely threo- and erythro-anethole β-hydroxymethylether and anethole glycol that are not detectable in the essential oil obtained by hydrodistillation. So, the relative abundance of the major components is comparable between these two methods for fennel seed up to 3 years from harvest and they can be used interchangeably depending on the purpose and amount of material. Furthermore, SHS-GC-FID can be used for assessment of maximum storage time

  13. Constraints on Pacific midplate swells from global depth-age and heat flow-age models

    NASA Astrophysics Data System (ADS)

    Stein, Carol A.; Stein, Seth

    Oceanic midplate swells are identified by shallow seafloor depths. In turn, models of the processes giving rise to these regions rely on assessments of how their depths, surface heat flow, and flexural properties differ from those for lithosphere which is presumed not to have been affected by these processes. Such comparisons have been inhibited because reference thermal models, which are assumed to describe unperturbed lithosphere, predict deeper depths and lower heat flow than typically observed for lithosphere older than 70 Ma. As a result, both depth and heat flow anomalies can be overestimated. To address this difficulty, we have derived model GDH1 (Global Depth and Heat flow) by joint fitting of heat flow and bathymetry. GDH1, which has a hotter and thinner lithosphere than previous models, fits the depth and heat flow data significantly better, including the data from older lithosphere previously treated as anomalous. It also provides an improved fit to depth-to-basement data for ocean drilling sites, and to geoid offsets across fracture zones. The improved fit occurs for depth-age data from both the DBDB-5 digital bathymetry, and from regional medians from ship tracks, which yield comparable depth-age curves. We use GDH1 to study three classes of midplate swells: the Hawaiian and other hot spot swells, the Darwin Rise area of widespread Cretaceous volcanism, and the Superswell, considered a present analogue to the Darwin Rise. Heat flow on the Hawaiian swell, though anomalously high with respect to previous reference models, is at most slightly high relative to GDH1. The situation is similar for the Bermuda, Cape Verde, and Crozet hot spots. The absence of a significant heat flow anomaly favors a primarily dynamic, rather than thermal, origin for these swells. Similarly, the present depths and heat flow for the Darwin Rise are consistent with GDH1, although they were anomalous with respect to previous reference models. The depth and heat flow data thus

  14. The Gifted Rating Scales-Preschool/Kindergarten Form: An Analysis of the Standardization Sample Based on Age, Gender, and Race

    ERIC Educational Resources Information Center

    Pfeiffer, Steven I.; Petscher, Yaacov; Jarosewich, Tania

    2007-01-01

    This study reports on an analysis of the standardization sample of a rating scale designed to assist in identification of gifted students. The Gifted Rating Scales-Preschool/Kindergarten Form (GRS-P) is based on a multidimensional model of giftedness designed for preschool and kindergarten students. Results provide support for: the internal…

  15. Development of the Thai healthy aging model: A grounded theory study.

    PubMed

    Thiamwong, Ladda; McManus, Michael S; Suwanno, Jom

    2013-06-01

    To develop a model of healthy aging from the perspective of Thais, a grounded theory approach, including in-depth interviews and focus groups, was used. A purposive sample of 39 community-dwelling adults aged 40-85 years old was interviewed. The Thai healthy aging model composed of three themes: normality, nature, and dharma. In Thai, they are called tham-ma-da, tham-ma-chat, and tham-ma, or "Thai 3Ts". The theme of normality encompasses subthemes of staying physically active by being involved in plenty of physical activities, and being mentally active with creative and thoughtful hobbies and work. The theme of nature encompasses subthemes of living simply and being careful with money. The theme of dharma encompasses subthemes of enjoyment through helping family and participating in community activities, staying away from stress and worries by talking openly and honestly with someone, making merit, and helping other people without expecting anything in return. A greater understanding of healthy aging is a benefit for older adults and healthcare providers in an intervention-design process. Research can contribute valuable information to shape policy for healthy aging as well.

  16. Lattice percolation approach to 3D modeling of tissue aging

    NASA Astrophysics Data System (ADS)

    Gorshkov, Vyacheslav; Privman, Vladimir; Libert, Sergiy

    2016-11-01

    We describe a 3D percolation-type approach to modeling of the processes of aging and certain other properties of tissues analyzed as systems consisting of interacting cells. Lattice sites are designated as regular (healthy) cells, senescent cells, or vacancies left by dead (apoptotic) cells. The system is then studied dynamically with the ongoing processes including regular cell dividing to fill vacant sites, healthy cells becoming senescent or dying, and senescent cells dying. Statistical-mechanics description can provide patterns of time dependence and snapshots of morphological system properties. The developed theoretical modeling approach is found not only to corroborate recent experimental findings that inhibition of senescence can lead to extended lifespan, but also to confirm that, unlike 2D, in 3D senescent cells can contribute to tissue's connectivity/mechanical stability. The latter effect occurs by senescent cells forming the second infinite cluster in the regime when the regular (healthy) cell's infinite cluster still exists.

  17. Age-aware solder performance models : level 2 milestone completion.

    SciTech Connect

    Neilsen, Michael K.; Vianco, Paul Thomas; Neidigk, Matthew Aaron; Holm, Elizabeth Ann

    2010-09-01

    Legislated requirements and industry standards are replacing eutectic lead-tin (Pb-Sn) solders with lead-free (Pb-free) solders in future component designs and in replacements and retrofits. Since Pb-free solders have not yet seen service for long periods, their long-term behavior is poorly characterized. Because understanding the reliability of Pb-free solders is critical to supporting the next generation of circuit board designs, it is imperative that we develop, validate and exercise a solder lifetime model that can capture the thermomechanical response of Pb-free solder joints in stockpile components. To this end, an ASC Level 2 milestone was identified for fiscal year 2010: Milestone 3605: Utilize experimentally validated constitutive model for lead-free solder to simulate aging and reliability of solder joints in stockpile components. This report documents the completion of this milestone, including evidence that the milestone completion criteria were met and a summary of the milestone Program Review.

  18. Overview of Modeling and Simulations of Plutonium Aging

    SciTech Connect

    Schwartz, A J; Wolfer, W G

    2007-04-24

    Computer-aided materials research is now an integral part of science and technology. It becomes particularly valuable when comprehensive experimental investigations and materials testing are too costly, hazardous, or of excessive duration; then, theoretical and computational studies can supplement and enhance the information gained from limited experimental data. Such is the case for improving our fundamental understanding of the properties of aging plutonium in the nuclear weapons stockpile. The question of the effects of plutonium aging on the safety, security, and reliability of the nuclear weapons stockpile emerged after the United States closed its plutonium manufacturing facility in 1989 and decided to suspend any further underground testing of nuclear weapons in 1992. To address this, the Department of Energy's National Nuclear Security Administration (NNSA) initiated a research program to investigate plutonium aging, i.e., the changes with time of properties of Pu-Ga alloys employed in the nuclear weapons and to develop models describing these changes sufficiently reliable to forecast them for several decades. The November 26, 2006 press release by the NNSA summarizes the conclusions of the investigation, '...there appear to be no serious or sudden changes occurring, or expected to occur, in plutonium that would affect performance of pits beyond the well-understood, gradual degradation of plutonium materials'. Furthermore, 'These studies show that the degradation of plutonium in our nuclear weapons will not affect warhead reliability for decades', then NNSA Administrator Linton Brooks said. 'It is now clear that although plutonium aging contributes, other factors control the overall life expectancy of nuclear weapons systems'. The origin of plutonium aging is the natural decay of certain plutonium isotopes. Specifically, it is the process of alpha decay in which a plutonium atom spontaneously splits into a 5 MeV alpha particle and an 85keV uranium recoil

  19. 12 CFR Appendix B to Part 1030 - Model Clauses and Sample Forms

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 8 2013-01-01 2013-01-01 false Model Clauses and Sample Forms B Appendix B to.... 1030, App. B Appendix B to Part 1030—Model Clauses and Sample Forms 1. Modifications. Institutions that.... Institutions may use inserts to a document (see Sample Form B-4) or fill-in blanks (see Sample Forms B-5,...

  20. Social and Physical Environmental Factors and Child Overweight in a Sample of American and Czech School-Aged Children: A Pilot Study

    ERIC Educational Resources Information Center

    Humenikova, Lenka; Gates, Gail E.

    2008-01-01

    Objective: To compare environmental factors that influence body mass index for age (BMI-for-age) between a sample of American and Czech school-aged children. Design: Pilot study. A parent questionnaire and school visits were used to collect data from parents and children. Setting: Public schools in 1 American and 2 Czech cities. Participants:…

  1. Automated biowaste sampling system, solids subsystem operating model, part 2

    NASA Technical Reports Server (NTRS)

    Fogal, G. L.; Mangialardi, J. K.; Stauffer, R. E.

    1973-01-01

    The detail design and fabrication of the Solids Subsystem were implemented. The system's capacity for the collection, storage or sampling of feces and vomitus from six subjects was tested and verified.

  2. Modeling senescence changes of the pubic symphysis in historic Italian populations: a comparison of the Rostock and forensic approaches to aging using transition analysis.

    PubMed

    Godde, Kanya; Hens, Samantha M

    2015-03-01

    Age-related anatomical changes to the surface of the pubic symphysis are well-documented in the literature. However, aligning these morphological changes with chronological age has proven problematic, often resulting in biased age estimates. Statistical modeling provides an avenue for forensic anthropologists and bioarchaeologists to increase the accuracy of traditional aging methods. Locating appropriate samples to use as a basis for modeling age estimations can be challenging due to differing sample age distributions and potentially varying patterns of senescence. We compared two approaches, Rostock and Forensic, coupled with a Bayesian methodology, to address these issues. Transition analysis was run specific to each method (which differ by sample selection). A Gompertz model was derived from an informative prior that yielded the mortality and senescence parameters for constructing highest posterior density ranges, i.e., coverages, which are analogous to age ranges. These age ranges were generated from both approaches and are presented as reference tables useful for historic male and female Italian samples. The age ranges produced from each approach were tested on an historic Italian sample, using cumulative binomial tests. These two approaches performed similarly, with the Forensic approach showing a slight advantage. However, the Forensic approach is unable to identify varying senescence patterns between populations, thus preference for one approach over the other will depend on research design. Finally, we demonstrate that while populations exhibit similar morphological changes with advancing age, there are no significant sex differences in these samples, and the timing of these changes varies from population to population.

  3. The Development of a New Analytical Model for the Identification of Saccharide Binders in Paint Samples

    PubMed Central

    Restivo, Annalaura; Colombini, Maria Perla; Bonaduce, Ilaria

    2012-01-01

    This paper describes a method for reliably identifying saccharide materials in paintings. Since the 3rd millennium B.C., polysaccharide materials such as plant gums, sugar, flour, and honey were used as binding media and sizing agents in paintings, illuminated manuscripts, and polychrome objects. Although it has been reported that plant gums have a stable composition, their identification in paint samples is often doubtful and rarely discussed. Our research was carried out independently at two different laboratories: the Getty Conservation Institute in Los Angeles, USA (GCI) and the Department of Chemistry and Industrial Chemistry of the University of Pisa, Italy (DCCI). It was shown in a previous stage of this research that the two methods give highly comparable data when analysing both reference paint samples and paint layers from art objects, thus the combined data was used to build a large database. In this study, the simultaneous presence of proteinaceous binders and pigments in fresh and artificially aged paint replicas was investigated, and it highlighted how these can affect the sugar profile of arabic, tragacanth, and fruit tree gums. The environmental contamination due to sugars from various plant tissues is also discussed. The results allowed the development of a new model for the reliable identification of saccharide binders in paintings based on the evaluation of markers that are stable to ageing and unaffected by pigments. This new model was applied to the sugar profiles obtained from the analysis of a large number of samples from murals, easel paintings, manuscripts, and polychrome objects from different geographical areas and dating from the 13th century BC to the 20th century AD, thus demonstrating its reliability. PMID:23166654

  4. The development of a new analytical model for the identification of saccharide binders in paint samples.

    PubMed

    Lluveras-Tenorio, Anna; Mazurek, Joy; Restivo, Annalaura; Colombini, Maria Perla; Bonaduce, Ilaria

    2012-01-01

    This paper describes a method for reliably identifying saccharide materials in paintings. Since the 3(rd) millennium B.C., polysaccharide materials such as plant gums, sugar, flour, and honey were used as binding media and sizing agents in paintings, illuminated manuscripts, and polychrome objects. Although it has been reported that plant gums have a stable composition, their identification in paint samples is often doubtful and rarely discussed. Our research was carried out independently at two different laboratories: the Getty Conservation Institute in Los Angeles, USA (GCI) and the Department of Chemistry and Industrial Chemistry of the University of Pisa, Italy (DCCI). It was shown in a previous stage of this research that the two methods give highly comparable data when analysing both reference paint samples and paint layers from art objects, thus the combined data was used to build a large database. In this study, the simultaneous presence of proteinaceous binders and pigments in fresh and artificially aged paint replicas was investigated, and it highlighted how these can affect the sugar profile of arabic, tragacanth, and fruit tree gums. The environmental contamination due to sugars from various plant tissues is also discussed. The results allowed the development of a new model for the reliable identification of saccharide binders in paintings based on the evaluation of markers that are stable to ageing and unaffected by pigments. This new model was applied to the sugar profiles obtained from the analysis of a large number of samples from murals, easel paintings, manuscripts, and polychrome objects from different geographical areas and dating from the 13(th) century BC to the 20(th) century AD, thus demonstrating its reliability.

  5. Modeling Diverse Pathways to Age Progressive Volcanism in Subduction Zones.

    NASA Astrophysics Data System (ADS)

    Kincaid, C. R.; Szwaja, S.; Sylvia, R. T.; Druken, K. A.

    2015-12-01

    One of the best, and most challenging clues to unraveling mantle circulation patterns in subduction zones comes in the form of age progressive volcanic and geochemical trends. Hard fought geological data from many subduction zones, like Tonga-Lau, the Cascades and Costa-Rica/Nicaragua, reveal striking temporal patterns used in defining mantle flow directions and rates. We summarize results from laboratory subduction models showing a range in circulation and thermal-chemical transport processes. These interaction styles are capable of producing such trends, often reflecting apparent instead of actual mantle velocities. Lab experiments use a glucose working fluid to represent Earth's upper mantle and kinematically driven plates to produce a range in slab sinking and related wedge transport patterns. Kinematic forcing assumes most of the super-adiabatic temperature gradient available to drive major downwellings is in the tabular slabs. Moreover, sinking styles for fully dynamic subduction depend on many complicating factors that are only poorly understood and which can vary widely even for repeated parameter combinations. Kinematic models have the benefit of precise, repeatable control of slab motions and wedge flow responses. Results generated with these techniques show the evolution of near-surface thermal-chemical-rheological heterogeneities leads to age progressive surface expressions in a variety of ways. One set of experiments shows that rollback and back-arc extension combine to produce distinct modes of linear, age progressive melt delivery to the surface through a) erosion of the rheological boundary layer beneath the overriding plate, and deformation and redistribution of both b) mantle residuum produced from decompression melting and c) formerly active, buoyant plumes. Additional experiments consider buoyant diapirs rising in a wedge under the influence of rollback, back-arc spreading and slab-gaps. Strongly deflected diapirs, experiencing variable rise

  6. Age, sex, and racial differences in harsh physical punishment: Results from a nationally representative United States sample

    PubMed Central

    Taillieu, Tamara L.; Afifi, Tracie O.; Mota, Natalie; Keyes, Katherine M.; Sareen, Jitender

    2015-01-01

    The purpose of this research was to examine age, sex, and racial differences in the prevalence of harsh physical punishment in childhood in a nationally representative sample of the United States. Data were from the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) collected in 2004 and 2005 (n = 34,653). Logistic regression analyses were conducted to examine age, sex, and racial differences in the prevalence of harsh physical punishment. Results suggest that the prevalence of harsh physical punishment has been decreasing among more recently born age groups; however, there appear to be sex and racial differences in this trend over time. The magnitude of the decrease appears to be stronger for males than for females. By race, the decrease in harsh physical punishment over time is only apparent among Whites; Black participants demonstrate little change over time, and harsh physical punishment seems to be increasing over time among Hispanics. Prevention and intervention efforts that educate about the links of physical punishment to negative outcomes and alternative non-physical discipline strategies may be particularly useful in reducing the prevalence of harsh physical punishment over time. PMID:25466426

  7. The relationship between hand preference consistency, health, and accidents in a sample of adults over the age of 65 years.

    PubMed

    Porac, Clare; Searleman, Alan

    2006-09-01

    As a result of the Coren and Halpern (1991) hypothesis that left hand preference may be associated with decreased survival fitness, there has been interest in exploring the relationship between hand preference and indices of health status. In a series of studies of university-aged adults, Hicks and his colleagues found a higher prevalence of accidental injuries, falls, and sleep problems among individuals with mixed, rather than left, hand preference. They argued that hand preference consistency, not side, may be a marker for possible reduction in health and well-being. We looked at the relationship between hand preference consistency and the prevalence of sleep problems, accidental injuries, falls, injuries from falls, and the prevalence of autoimmune and other illnesses in a sample of 1277 adults between the ages of 65 and 100 years. Of those participants who reported a recent fall, mixed-handers were more likely to report a higher number of injuries from these falls when compared to the reports of consistent-handers. In contrast to the previous findings of Hicks et al., and highlighting the value of including broader age ranges, all other comparisons showed no differences between the two hand preference types.

  8. Age, sex, and racial differences in harsh physical punishment: results from a nationally representative United States sample.

    PubMed

    Taillieu, Tamara L; Afifi, Tracie O; Mota, Natalie; Keyes, Katherine M; Sareen, Jitender

    2014-12-01

    The purpose of this research was to examine age, sex, and racial differences in the prevalence of harsh physical punishment in childhood in a nationally representative sample of the United States. Data were from the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) collected in 2004 and 2005 (n=34,653). Logistic regression analyses were conducted to examine age, sex, and racial differences in the prevalence of harsh physical punishment. Results suggest that the prevalence of harsh physical punishment has been decreasing among more recently born age groups; however, there appear to be sex and racial differences in this trend over time. The magnitude of the decrease appears to be stronger for males than for females. By race, the decrease in harsh physical punishment over time is only apparent among Whites; Black participants demonstrate little change over time, and harsh physical punishment seems to be increasing over time among Hispanics. Prevention and intervention efforts that educate about the links of physical punishment to negative outcomes and alternative non-physical discipline strategies may be particularly useful in reducing the prevalence of harsh physical punishment over time.

  9. Death anxiety in a national sample of United States funeral directors and its relationship with death exposure, age, and sex.

    PubMed

    Harrawood, Laura K; White, Lyle J; Benshoff, John J

    The purpose of this study is to examine the relationship between the level of death anxiety among a national sample of United States funeral directors with varying levels of death exposure, age, and sex. Utilizing the Multidimensional Fear of Death Scale (MFODS), the results showed a significant, but weak negative relationship between levels of death anxiety and the participants' reported number of funerals attended per year. The correlation between death anxiety scores and the number of reported embalming cases performed yearly was, however, not significant. We found a significant negative correlation between death anxiety and age in both men and women funeral directors. The difference in the death anxiety scores between men (n=166) and women (n=38) funeral directors was not significant. There was a significant negative correlation with age in both men and women in several fears of death including fear of the dying process, fear for significant others, and fear of premature death. The significant negative correlations were stronger for women than men across all three subscales. Results, direction for further research, and implications of the findings for mental health workers are discussed.

  10. A multidomain cascade model of early childhood risk factors associated with oppositional defiant disorder symptoms in a community sample of 6-year-olds.

    PubMed

    Lavigne, John V; Gouze, Karen R; Hopkins, Joyce; Bryant, Fred B

    2016-11-01

    The present study examined a cascade model of age 4 and 5 contextual, parent, parenting, and child factors on symptoms of oppositional defiant disorder (ODD) at age 6 in a diverse community sample of 796 children. Contextual factors include socioeconomic status, family stress, and conflict; parent factors included parental depression; parenting factors included parental hostility, support, and scaffolding skills; child factors included child effortful control (EC), negative affect (NA), and sensory regulation. Direct effects of age 5 conflict, hostility, scaffolding, EC, and NA were found. Significant indirect, cascading effects on age 6 ODD symptom levels were noted for age 4 socioeconomic status via age 5 conflict and scaffolding skills; age 4 parental depression via age 5 child NA; age 4 parental hostility and support via age 5 EC; age 4 support via age 5 EC; and age 4 attachment via age 5 EC. Parenting contributed to EC, and the age 5 EC effects on subsequent ODD symptom levels were distinct from age 5 parental contributions. Scaffolding and ODD symptoms may have a reciprocal relationship. These results highlight the importance of using a multidomain model to examine factors associated with ODD symptoms early in the child's grammar school years.

  11. Modeling age-of-onset: Cox model with latent major gene effects

    SciTech Connect

    Li, H.; Thompson, E.A.

    1994-09-01

    Analysis of age-of-onset is a key factor in the segregation and linkage analysis of complex genetic traits, but is complicated by the censoring of unaffected individuals. Most previous work has used parametric distributional assumptions, but it is hard to characterize the distribution of age-of-onset by a single distribution. Other approaches discretize age-of-onset and use logistic regression to model incidence; this approach does not use the information fully. Frailty models have been used for age-of-oset in the biostatistics literature, but these models do not lend themselves to modeling the correlations due to genetic effects which segregate within a family. Here, we propose use of the Cox model with latent major gene effects; conditional on the major genotypes, Cox`s proportional hazards model is used for age-of-onset for each individual. This is a semiparametric model; we do not specify the baseline hazard function. Likelihood analysis of such models is restricted by the difficulty in evaluating of maximizing the likelihood, especially when data are available for some of the members of an extended pedigree. Markov chain Monte Carlo permits genotypic configurations to be realized from the posterior distributions given a current model and the observed data. Hence methods for likelihood analysis can be developed: Monte Carlo EM is used for estimation of the parameters and their variance-covariance matrix. Markers and observed covariates are easily incorporated into this analysis. We present the model, methods for likelihood analysis and the results of a simulation study. The results are comparable with those based on a Cox model with known genotypic dependence in a pedigree. An early-onset Alzheimer`s pedigree and some breast cancer pedigrees have been used as real data examples. Some possible extensions are also discussed.

  12. A review of single-sample-based models and other approaches for radiocarbon dating of dissolved inorganic carbon in groundwater

    USGS Publications Warehouse

    Han, L. F; Plummer, Niel

    2016-01-01

    Numerous methods have been proposed to estimate the pre-nuclear-detonation 14C content of dissolved inorganic carbon (DIC) recharged to groundwater that has been corrected/adjusted for geochemical processes in the absence of radioactive decay (14C0) - a quantity that is essential for estimation of radiocarbon age of DIC in groundwater. The models/approaches most commonly used are grouped as follows: (1) single-sample-based models, (2) a statistical approach based on the observed (curved) relationship between 14C and δ13C data for the aquifer, and (3) the geochemical mass-balance approach that constructs adjustment models accounting for all the geochemical reactions known to occur along a groundwater flow path. This review discusses first the geochemical processes behind each of the single-sample-based models, followed by discussions of the statistical approach and the geochemical mass-balance approach. Finally, the applications, advantages and limitations of the three groups of models/approaches are discussed.The single-sample-based models constitute the prevailing use of 14C data in hydrogeology and hydrological studies. This is in part because the models are applied to an individual water sample to estimate the 14C age, therefore the measurement data are easily available. These models have been shown to provide realistic radiocarbon ages in many studies. However, they usually are limited to simple carbonate aquifers and selection of model may have significant effects on 14C0 often resulting in a wide range of estimates of 14C ages.Of the single-sample-based models, four are recommended for the estimation of 14C0 of DIC in groundwater: Pearson's model, (Ingerson and Pearson, 1964; Pearson and White, 1967), Han & Plummer's model (Han and Plummer, 2013), the IAEA model (Gonfiantini, 1972; Salem et al., 1980), and Oeschger's model (Geyh, 2000). These four models include all processes considered in single-sample-based models, and can be used in different ranges of

  13. Sample-dependent phase transitions in disordered exclusion models

    NASA Astrophysics Data System (ADS)

    Enaud, C.; Derrida, B.

    2004-04-01

    We give numerical evidence that the location of the first-order phase transition between the low- and the high-density phases of the one-dimensional asymmetric simple exclusion process with open boundaries becomes sample dependent when quenched disorder is introduced for the hopping rates.

  14. The topomer-sampling model of protein folding

    PubMed Central

    Debe, Derek A.; Carlson, Matt J.; Goddard, William A.

    1999-01-01

    Clearly, a protein cannot sample all of its conformations (e.g., ≈3100 ≈ 1048 for a 100 residue protein) on an in vivo folding timescale (<1 s). To investigate how the conformational dynamics of a protein can accommodate subsecond folding time scales, we introduce the concept of the native topomer, which is the set of all structures similar to the native structure (obtainable from the native structure through local backbone coordinate transformations that do not disrupt the covalent bonding of the peptide backbone). We have developed a computational procedure for estimating the number of distinct topomers required to span all conformations (compact and semicompact) for a polypeptide of a given length. For 100 residues, we find ≈3 × 107 distinct topomers. Based on the distance calculated between different topomers, we estimate that a 100-residue polypeptide diffusively samples one topomer every ≈3 ns. Hence, a 100-residue protein can find its native topomer by random sampling in just ≈100 ms. These results suggest that subsecond folding of modest-sized, single-domain proteins can be accomplished by a two-stage process of (i) topomer diffusion: random, diffusive sampling of the 3 × 107 distinct topomers to find the native topomer (≈0.1 s), followed by (ii) intratopomer ordering: nonrandom, local conformational rearrangements within the native topomer to settle into the precise native state. PMID:10077555

  15. Cellular models and therapies for age-related macular degeneration

    PubMed Central

    Forest, David L.; Johnson, Lincoln V.; Clegg, Dennis O.

    2015-01-01

    ABSTRACT Age-related macular degeneration (AMD) is a complex neurodegenerative visual disorder that causes profound physical and psychosocial effects. Visual impairment in AMD is caused by the loss of retinal pigmented epithelium (RPE) cells and the light-sensitive photoreceptor cells that they support. There is currently no effective treatment for the most common form of this disease (dry AMD). A new approach to treating AMD involves the transplantation of RPE cells derived from either human embryonic or induced pluripotent stem cells. Multiple clinical trials are being initiated using a variety of cell therapies. Although many animal models are available for AMD research, most do not recapitulate all aspects of the disease, hampering progress. However, the use of cultured RPE cells in AMD research is well established and, indeed, some of the more recently described RPE-based models show promise for investigating the molecular mechanisms of AMD and for screening drug candidates. Here, we discuss innovative cell-culture models of AMD and emerging stem-cell-based therapies for the treatment of this vision-robbing disease. PMID:26035859

  16. Improved age modelling and high-precision age estimates of late Quaternary tephras, for accurate palaeoclimate reconstruction

    NASA Astrophysics Data System (ADS)

    Blockley, Simon P. E.; Bronk Ramsey, C.; Pyle, D. M.

    2008-10-01

    The role of tephrochronology, as a dating and stratigraphic tool, in precise palaeoclimate and environmental reconstruction, has expanded significantly in recent years. The power of tephrochronology rests on the fact that a tephra layer can stratigraphically link records at the resolution of as little as a few years, and that the most precise age for a particular tephra can be imported into any site where it is found. In order to maximise the potential of tephras for this purpose it is necessary to have the most precise and robustly tested age estimate possible available for key tephras. Given the varying number and quality of dates associated with different tephras it is important to be able to build age models to test competing tephra dates. Recent advances in Bayesian age modelling of dates in sequence have radically extended our ability to build such stratigraphic age models. As an example of the potential here we use Bayesian methods, now widely applied, to examine the dating of some key Late Quaternary tephras from Italy. These are: the Agnano Monte Spina Tephra (AMST), the Neapolitan Yellow Tuff (NYT) and the Agnano Pomici Principali (APP), and all of them have multiple estimates of their true age. Further, we use the Bayesian approaches to generate a revised mixed radiocarbon/varve chronology for the important Lateglacial section of the Lago Grande Monticchio record, as a further illustration of what can be achieved by a Bayesian approach. With all three tephras we were able to produce viable model ages for the tephra, validate the proposed 40Ar/ 39Ar age ranges for these tephras, and provide relatively high precision age models. The results of the Bayesian integration of dating and stratigraphic information, suggest that the current best 95% confidence calendar age estimates for the AMST are 4690-4300 cal BP, the NYT 14320-13900 cal BP, and the APP 12380-12140 cal BP.

  17. Age and structure of a model vapour-deposited glass

    PubMed Central

    Reid, Daniel R.; Lyubimov, Ivan; Ediger, M. D.; de Pablo, Juan J.

    2016-01-01

    Glass films prepared by a process of physical vapour deposition have been shown to have thermodynamic and kinetic stability comparable to those of ordinary glasses aged for thousands of years. A central question in the study of vapour-deposited glasses, particularly in light of new knowledge regarding anisotropy in these materials, is whether the ultra-stable glassy films formed by vapour deposition are ever equivalent to those obtained by liquid cooling. Here we present a computational study of vapour deposition for a two-dimensional glass forming liquid using a methodology, which closely mimics experiment. We find that for the model considered here, structures that arise in vapour-deposited materials are statistically identical to those observed in ordinary glasses, provided the two are compared at the same inherent structure energy. We also find that newly deposited hot molecules produce cascades of hot particles that propagate far into the film, possibly influencing the relaxation of the material. PMID:27762262

  18. Ploidy, sex and crossing over in an evolutionary aging model

    NASA Astrophysics Data System (ADS)

    Lobo, Matheus P.; Onody, Roberto N.

    2006-02-01

    Nowadays, many forms of reproduction coexist in nature: Asexual, sexual, apomictic and meiotic parthenogenesis, hermaphroditism and parasex. The mechanisms of their evolution and what made them successful reproductive alternatives are very challenging and debated questions. Here, using a simple evolutionary aging model, we give a possible scenario. By studying the performance of populations where individuals may have diverse characteristics-different ploidies, sex with or without crossing over, as well as the absence of sex-we find an evolution sequence that may explain why there are actually two major or leading groups: Sexual and asexual. We also investigate the dependence of these characteristics on different conditions of fertility and deleterious mutations. Finally, if the primeval organisms on Earth were, in fact, asexual individuals we conjecture that the sexual form of reproduction could have more easily been set and found its niche during a period of low-intensity mutations.

  19. An Importance Sampling EM Algorithm for Latent Regression Models

    ERIC Educational Resources Information Center

    von Davier, Matthias; Sinharay, Sandip

    2007-01-01

    Reporting methods used in large-scale assessments such as the National Assessment of Educational Progress (NAEP) rely on latent regression models. To fit the latent regression model using the maximum likelihood estimation technique, multivariate integrals must be evaluated. In the computer program MGROUP used by the Educational Testing Service for…

  20. Visual Sample Plan (VSP) Models and Code Verification

    SciTech Connect

    Gilbert, Richard O.; Davidson, James R.; Wilson, John E.; Pulsipher, Brent A.

    2001-03-06

    VSP is an easy to use, visual and graphic software tool being developed to select the right number and location of environmental samples so that the results of statistical tests performed to provide input to environmental decisions have the required confidence and performance. It is a significant help for implementing the 6th and 7th steps of the Data Quality Objectives (DQO) planning process ("Specify Tolerable Limits on Decision Errors" and "Optimize the Design for Obtaining Data," respectively).

  1. The mediating role of sexual and nonsexual communication between relationship and sexual satisfaction in a sample of college-age heterosexual couples.

    PubMed

    Mark, Kristen P; Jozkowski, Kristen N

    2013-01-01

    This study aimed to examine in a sample of college-age heterosexual couples the relations between (a) relationship and sexual satisfaction and (b) sexual and nonsexual communication. The authors tested a mediation model whereby couples' relationship satisfaction was hypothesized to predict couples' sexual satisfaction by way of sexual and nonsexual communication levels. Participants were 266 individuals (133 couples) who completed measures of satisfaction and communication independently of their partner. A mediation model, tested with structural equation modeling, showed the degree to which couples were relationally satisfied was positively related to their level of sexual and nonsexual communication, which, in turn, was positively associated with their degree of sexual satisfaction. Results indicate that levels of sexual and nonsexual communication among couples affect the link between relationship and sexual satisfaction. Such findings may have important implications for college-age couples in committed relationships who are looking to improve satisfaction as well as for therapists, counselors, and educators who work with these couples to improve relationship and/or sexual satisfaction.

  2. Sample locality map and analytical data for potassium-argon ages in the Port Moller, Stepovak Bay, and Simeonof Island quadrangles, Alaska Peninsula

    USGS Publications Warehouse

    Wilson, Frederic H.; Shew, Nora B.; DuBois, Gregory D.; Bie, Scott W.

    1994-01-01

    Potassium-argon age determinations for 84 volcanic, intrusive, and hydrothermally altered rocks from the Port Moller, Stepovak Bay, and Simeonof Island quadrangles are reported here. Of these age determinations, 78 samples were analyzed as part of Alaska Mineral Resource Assessment Program (AMRAP) studies in the Port Moller, Stepovak Bay, and Simeonof Island quadrangles. Age deter- minations for 6 of the samples have been previously published (Burk, 1965; Kienle and Turner, 1976; Wilson and others, 1981). This report consists of a sample location map, analytical data (table 1), and rock descriptions (table 2).

  3. Child Weight Growth Trajectory and its Determinants in a Sample of Iranian Children from Birth until 2 Years of Age

    PubMed Central

    Hosseini, Sayed-Mohsen; Maracy, Mohamad-Reza; Sarrafzade, Sheida; Kelishadi, Roya

    2014-01-01

    Background: Growth is one of the most important indices in child health. The best and most effective way to investigate child health is measuring the physical growth indices such as weight, height and head circumference. Among these measures, weight growth is the simplest and the most effective way to determine child growth status. Weight trend at a given age is the result of cumulative growth experience, whereas growth velocity represents what is happening at the time. Methods: This longitudinal study was conducted among 606 children repeatedly measured from birth until 2 years of age. We used linear mixed model to analyze repeated measures and to determine factors affecting the growth trajectory. LOWESS smooth curve was used to draw velocity curves. Results: Gender, child rank, birth status and feeding mode had a significant effect on weight trajectory. Boys had higher weight during the study. Infants with exclusive breast feeding had higher weight than other infants. Boys had higher growth velocity up to age 6 month. Breast fed infants had higher growth velocity up to 6 month, but thereafter the velocity was higher in other infants. Conclusions: Many of the studies have investigated child growth, but most of them used cross-sectional design. In this study, we used longitudinal method to determine effective factors on weight trend in children from birth until 2-year-old. The effects of perinatal factors on further growth should be considered for prevention of growth disorders and their late complications. PMID:24829720

  4. Sensitivity analysis of the age-structured malaria transmission model

    NASA Astrophysics Data System (ADS)

    Addawe, Joel M.; Lope, Jose Ernie C.

    2012-09-01

    We propose an age-structured malaria transmission model and perform sensitivity analyses to determine the relative importance of model parameters to disease transmission. We subdivide the human population into two: preschool humans (below 5 years) and the rest of the human population (above 5 years). We then consider two sets of baseline parameters, one for areas of high transmission and the other for areas of low transmission. We compute the sensitivity indices of the reproductive number and the endemic equilibrium point with respect to the two sets of baseline parameters. Our simulations reveal that in areas of either high or low transmission, the reproductive number is most sensitive to the number of bites by a female mosquito on the rest of the human population. For areas of low transmission, we find that the equilibrium proportion of infectious pre-school humans is most sensitive to the number of bites by a female mosquito. For the rest of the human population it is most sensitive to the rate of acquiring temporary immunity. In areas of high transmission, the equilibrium proportion of infectious pre-school humans and the rest of the human population are both most sensitive to the birth rate of humans. This suggests that strategies that target the mosquito biting rate on pre-school humans and those that shortens the time in acquiring immunity can be successful in preventing the spread of malaria.

  5. Childhood trauma and suicide risk in a sample of young individuals aged 14-35 years in southern Brazil.

    PubMed

    Barbosa, Luana Porto; Quevedo, Luciana; da Silva, Giovanna Del Grande; Jansen, Karen; Pinheiro, Ricardo Tavares; Branco, Jerônimo; Lara, Diogo; Oses, Jean; da Silva, Ricardo Azevedo

    2014-07-01

    Suicide is among the main causes of death of people aged between 15 and 44 years old. Childhood trauma is an important risk factor for suicide. Hence, the objective of this study was to verify the relationship between childhood trauma and current suicide risk (suicidal behavior and ideation) in individuals aged 14-35 years, in the city of Pelotas, Brazil. This is a cross-sectional, population-based study. Sample selection was performed by clusters. Suicide risk was evaluated using the Mini International Neuropsychiatric Interview (MINI) and Childhood trauma was assessed with the Childhood Trauma Questionnaire (CTQ). Moreover, the participants responded to a questionnaire concerning socioeconomic status, work, and substance use. The sample was composed of 1,380 individuals. The prevalence of suicide risk was 11.5%. The prevalence figures of childhood trauma were 15.2% (emotional neglect), 13.5% (physical neglect), 7.6% (sexual abuse), 10.1% (physical abuse), and 13.8% (emotional abuse). Suicide risk was associated (p<.001) with gender, work, alcohol abuse, tobacco use, and all types of childhood trauma. The odds of suicide risk were higher in women (OR=1.8), people who were not currently working (OR=2.3), individuals who presented alcohol abuse (OR=2.6), and among tobacco smokers (OR=3.4). Moreover, suicide risk was increased in all types of trauma: emotional neglect (OR=3.7), physical neglect (OR=2.8), sexual abuse (OR=3.4), physical abuse (OR=3.1), and emotional abuse (OR=6.6). Thus, preventing early trauma may reduce suicide risk in young individuals.

  6. Compliance with WHO IYCF Indicators and Dietary Intake Adequacy in a Sample of Malaysian Infants Aged 6–23 Months

    PubMed Central

    Khor, Geok Lin; Tan, Sue Yee; Tan, Kok Leong; Chan, Pauline S.; Amarra, Maria Sofia V.

    2016-01-01

    Background: The 2010 World Health Organisation (WHO) Infant and Young Child Feeding (IYCF) indicators are useful for monitoring feeding practices. Methods: A total sample of 300 subjects aged 6 to 23 months was recruited from urban suburbs of Kuala Lumpur and Putrajaya. Compliance with each IYCF indicator was computed according to WHO recommendations. Dietary intake based on two-day weighed food records was obtained from a sub-group (N = 119) of the total sample. The mean adequacy ratio (MAR) value was computed as an overall measure of dietary intake adequacy. Contributions of core IYCF indicators to MAR were determined by multinomial logistic regression. Results: Generally, the subjects showed high compliance for (i) timely introduction of complementary foods at 6 to 8 months (97.9%); (ii) minimum meal frequency among non-breastfed children aged 6 to 23 months (95.2%); (iii) consumption of iron-rich foods at 6 to 23 months (92.3%); and minimum dietary diversity (78.0%). While relatively high proportions achieved the recommended intake levels for protein (87.4%) and iron (71.4%), lower proportions attained the recommendations for calcium (56.3%) and energy (56.3%). The intake of micronutrients was generally poor. The minimum dietary diversity had the greatest contribution to MAR (95% CI: 3.09, 39.87) (p = 0.000) among the core IYCF indicators. Conclusion: Malaysian urban infants and toddlers showed moderate to high compliance with WHO IYCF indicators. The robustness of the analytical approach in this study in quantifying contributions of IYCF indicators to MAR should be further investigated. PMID:27916932

  7. Application of Sampling Based Model Predictive Control to an Autonomous Underwater Vehicle

    DTIC Science & Technology

    2010-07-01

    55 Application of Sampling Based Model Predictive Control to an Autonomous Underwater Vehicle Unmanned Underwater Vehicles (UUVs) can be utilized...the vehicle can feasibly traverse. As a result, Sampling- Based Model Predictive Control (SBMPC) is proposed to simultaneously generate control...inputs and system trajectories for an autonomous underwater vehicle (AUV). The algorithm combines the benefits of sampling- based motion planning with

  8. A Note on Sample Size and Solution Propriety for Confirmatory Factor Analytic Models

    ERIC Educational Resources Information Center

    Jackson, Dennis L.; Voth, Jennifer; Frey, Marc P.

    2013-01-01

    Determining an appropriate sample size for use in latent variable modeling techniques has presented ongoing challenges to researchers. In particular, small sample sizes are known to present concerns over sampling error for the variances and covariances on which model estimation is based, as well as for fit indexes and convergence failures. The…

  9. Sample Size Determination for Regression Models Using Monte Carlo Methods in R

    ERIC Educational Resources Information Center

    Beaujean, A. Alexander

    2014-01-01

    A common question asked by researchers using regression models is, What sample size is needed for my study? While there are formulae to estimate sample sizes, their assumptions are often not met in the collected data. A more realistic approach to sample size determination requires more information such as the model of interest, strength of the…

  10. Victim age-based subtypes of juveniles adjudicated for sexual offenses: comparisons across domains in an outpatient sample.

    PubMed

    Fanniff, Amanda M; Kolko, David J

    2012-06-01

    Adolescents adjudicated for sexual offenses are a heterogeneous group. The identification of more homogeneous subgroups of offenders may enable improved treatment, as the specific risks and needs presented by each group could be more effectively targeted. The current study examines three subgroups derived based on the age of victim(s), a popular method of subtyping that has mixed empirical support, using a sample of 176 males adjudicated for a sexual offense and court-ordered to participate in a community-based collaborative intervention program that integrates treatment and probationary services. Differences expected between groups based on theories regarding victim-age based subtypes are examined, in addition to differences consistently identified in prior research. Results indicate that these three subgroups are more similar than different, although some expected differences were found. Juveniles with child victims were more likely to have male victims and biologically related victims. Juveniles with peer/adult victims were more likely to have poor monitoring by their parents and more likely to have been arrested again. Juveniles with mixed types of victims appeared similar to juveniles with child victims on some variables and similar to those with peer/adult victims on others. Treatment implications and future directions for research are discussed. Typologies based on clinical characteristics of the youth rather than offense characteristics may have more promise for identifying meaningful subgroups.

  11. The emergence of spanking among a representative sample of children under 2 years of age in north Carolina.

    PubMed

    Zolotor, Adam J; Robinson, T Walker; Runyan, Desmond K; Barr, Ronald G; Murphy, Robert A

    2011-01-01

    Spanking is common in the United States but less common in many European countries in which it has been outlawed. Being spanked has been associated with child abuse victimization, poor self-esteem, impaired parent-child relationships, and child and adult mental health, substance abuse, and behavioral consequences. Being spanked as a child has also been shown to increase the likelihood of abusing one's own children or spouse as an adult. Spanking of very young children less than two is almost never recommended even among experts that consider spanking as reasonable in some circumstances. Using a cross-sectional anonymous telephone survey, we describe spanking rates among a representative sample of North Carolina mothers of children less than 2 years old and the association of spanking with demographic characteristics. A substantial proportion of mothers admit to spanking their very young children. The rate of spanking in the last year among all maternal respondents was 30%. Over 5% of the mothers of 3-month olds reported spanking. Over 70% of the mothers of 23-month olds reported spanking. Increased spanking was associated with higher age of the child and lower maternal age. With every month of age, a child had 27% increased odds of being spanked. Early spanking has been shown to be associated with poor cognitive development in early childhood. Further, early trauma has been shown to have significant effects on the early developing brain. It is therefore critical that health and human services professionals address the risk of corporal punishment as a method of discipline early in the life of the child. The spanking of very young children may be an appropriate locus for policy and legislative debates regarding corporal punishment.

  12. Large Sample Hydrology : Building an international sample of watersheds to improve consistency and robustness of model evaluation

    NASA Astrophysics Data System (ADS)

    Mathevet, Thibault; Kumar, Rohini; Gupta, Hoshin; Vaze, Jai; Andréassian, Vazken

    2015-04-01

    This poster introduces the aims of the Large Sample Hydrology working group (LSH-WG) of the new IAHS Panta Rhei decade (2013-2022). The aim of the LSH-WG is to promote large sample hydrology, as discussed by Gupta et al. (2014) and to invite the community to collaborate on building and sharing a comprehensive and representative world-wide sample of watershed datasets. By doing so, LSH will allow the community to work towards 'hydrological consistency' (Martinez and Gupta, 2011) as a basis for hydrologic model development and evaluation, thereby increasing robustness of the model evaluation process. Classical model evaluation metrics based on 'robust statistics' are needed, but clearly not sufficient: multi-criteria assessments based on multiple hydrological signatures can help to better characterize hydrological functioning. Further, large-sample data sets can greatly facilitate: (i) improved understanding through rigorous testing and comparison of competing model hypothesis and structures, (ii) improved robustness of generalizations through statistical analyses that minimize the influence of outliers and case-specific studies, (iii) classification, regionalization and model transfer across a broad diversity of hydrometeorological contexts, and (iv) estimation of predictive uncertainties at a location and across locations (Mathevet et al., 2006; Andréassian et al., 2009; Gupta et al., 2014) References Andréassian, V., Perrin, C., Berthet, L., Le Moine, N., Lerat, J., Loumagne, C., Oudin, L., Mathevet, T., Ramos, M. H., and Valéry, A.: Crash tests for a standardized evaluation of hydrological models, Hydrology and Earth System Sciences, 1757-1764, 2009. Gupta, H. V., Perrin, C., Blöschl, G., Montanari, A., Kumar, R., Clark, M., and Andréassian, V.: Large-sample hydrology: a need to balance depth with breadth, Hydrol. Earth Syst. Sci., 18, 463-477, doi:10.5194/hess-18-463-2014, 2014. Martinez, G. F., and H. V.Gupta (2011), Hydrologic consistency as a basis for

  13. Ensemble bayesian model averaging using markov chain Monte Carlo sampling

    SciTech Connect

    Vrugt, Jasper A; Diks, Cees G H; Clark, Martyn P

    2008-01-01

    Bayesian model averaging (BMA) has recently been proposed as a statistical method to calibrate forecast ensembles from numerical weather models. Successful implementation of BMA however, requires accurate estimates of the weights and variances of the individual competing models in the ensemble. In their seminal paper (Raftery etal. Mon Weather Rev 133: 1155-1174, 2(05)) has recommended the Expectation-Maximization (EM) algorithm for BMA model training, even though global convergence of this algorithm cannot be guaranteed. In this paper, we compare the performance of the EM algorithm and the recently developed Differential Evolution Adaptive Metropolis (DREAM) Markov Chain Monte Carlo (MCMC) algorithm for estimating the BMA weights and variances. Simulation experiments using 48-hour ensemble data of surface temperature and multi-model stream-flow forecasts show that both methods produce similar results, and that their performance is unaffected by the length of the training data set. However, MCMC simulation with DREAM is capable of efficiently handling a wide variety of BMA predictive distributions, and provides useful information about the uncertainty associated with the estimated BMA weights and variances.

  14. Dynamical opacity-sampling models of Mira variables - I. Modelling description and analysis of approximations

    NASA Astrophysics Data System (ADS)

    Ireland, M. J.; Scholz, M.; Wood, P. R.

    2008-12-01

    We describe the Cool Opacity-sampling Dynamic EXtended (CODEX) atmosphere models of Mira variable stars, and examine in detail the physical and numerical approximations that go in-to the model creation. The CODEX atmospheric models are obtained by computing the temperature and the chemical and radiative states of the atmospheric layers, assuming gas pressure and velocity profiles from Mira pulsation models, which extend from near the H-burning shell to the outer layers of the atmosphere. Although the code uses the approximation of Local Thermodynamic Equilibrium (LTE) and a grey approximation in the dynamical atmosphere code, many key observable quantities, such as infrared diameters and low-resolution spectra, are predicted robustly in spite of these approximations. We show that in visible light, radiation from Mira variables is dominated by fluorescence scattering processes, and that the LTE approximation likely underpredicts visible-band fluxes by a factor of 2.

  15. Age model for a continuous, ca 250-ka Quaternary lacustrine record from Bear Lake, Utah-Idaho

    USGS Publications Warehouse

    Colman, Steven M.; Kaufman, D.S.; Bright, Jordon; Heil, C.; King, J.W.; Dean, W.E.; Rosenbaum, J.G.; Forester, R.M.; Bischoff, J.L.; Perkins, Marie; McGeehin, J.P.

    2006-01-01

    The Quaternary sediments sampled by continuous 120-m-long drill cores from Bear Lake (Utah-Idaho) comprise one of the longest lacustrine sequences recovered from an extant lake. The cores serve as a good case study for the construction of an age model for sequences that extend beyond the range of radiocarbon dating. From a variety of potential age indicators, we selected a combination of radiocarbon ages, one magnetic excursion (correlated to a standard sequence), and a single Uranium-series age to develop an initial data set. The reliability of the excursion and U-series data require consideration of their position with respect to sediments of inferred interglacial character, but not direct correlation with other paleoclimate records. Data omitted from the age model include amino acid age estimates, which have a large amount of scatter, and tephrochronology correlations, which have relatively large uncertainties. Because the initial data set was restricted to the upper half of the BL00-1 core, we inferred additional ages by direct correlation to the independently dated paleoclimate record from Devils Hole. We developed an age model for the entire core using statistical methods that consider both the uncertainties of the original data and that of the curve-fitting process, with a combination of our initial data set and the climate correlations as control points. This age model represents our best estimate of the chronology of deposition in Bear Lake. Because the age model contains assumptions about the correlation of Bear Lake to other climate records, the model cannot be used to address some paleoclimate questions, such as phase relationships with other areas.

  16. Statistical analysis of biomechanical properties of the adult skull and age-related structural changes by sex in a Japanese forensic sample.

    PubMed

    Torimitsu, Suguru; Nishida, Yoshifumi; Takano, Tachio; Koizumi, Yoshinori; Makino, Yohsuke; Yajima, Daisuke; Hayakawa, Mutsumi; Inokuchi, Go; Motomura, Ayumi; Chiba, Fumiko; Otsuka, Katsura; Kobayashi, Kazuhiro; Odo, Yuriko; Iwase, Hirotaro

    2014-01-01

    The purpose of this research was to investigate the biomechanical properties of the adult human skull and the structural changes that occur with age in both sexes. The heads of 94 Japanese cadavers (54 male cadavers, 40 female cadavers) autopsied in our department were used in this research. A total of 376 cranial samples, four from each skull, were collected. Sample fracture load was measured by a bending test. A statistically significant negative correlation between the sample fracture load and cadaver age was found. This indicates that the stiffness of cranial bones in Japanese individuals decreases with age, and the risk of skull fracture thus probably increases with age. Prior to the bending test, the sample mass, the sample thickness, the ratio of the sample thickness to cadaver stature (ST/CS), and the sample density were measured and calculated. Significant negative correlations between cadaver age and sample thickness, ST/CS, and the sample density were observed only among the female samples. Computerized tomographic (CT) images of 358 cranial samples were available. The computed tomography value (CT value) of cancellous bone which refers to a quantitative scale for describing radiodensity, cancellous bone thickness and cortical bone thickness were measured and calculated. Significant negative correlation between cadaver age and the CT value or cortical bone thickness was observed only among the female samples. These findings suggest that the skull is substantially affected by decreased bone metabolism resulting from osteoporosis. Therefore, osteoporosis prevention and treatment may increase cranial stiffness and reinforce the skull structure, leading to a decrease in the risk of skull fractures.

  17. Aging Through Hierarchical Coalescence in the East Model

    NASA Astrophysics Data System (ADS)

    Faggionato, A.; Martinelli, F.; Roberto, C.; Toninelli, C.

    2012-01-01

    We rigorously analyze the low temperature non-equilibrium dynamics of the East model, a special example of a one dimensional oriented kinetically constrained particle model, when the initial distribution is different from the reversible one and for times much smaller than the global relaxation time. This setting has been intensively studied in the physics literature to analyze the slow dynamics which follows a sudden quench from the liquid to the glass phase. In the limit of zero temperature (i.e. a vanishing density of vacancies) and for initial distributions such that the vacancies form a renewal process, we prove that the density of vacancies, the persistence function and the two-time autocorrelation function behave as staircase functions with several plateaux. Furthermore the two-time autocorrelation function displays an aging behavior. We also provide a sharp description of the statistics of the domain length as a function of time, a domain being the interval between two consecutive vacancies. When the initial renewal process has finite mean, our results confirm (and generalize) previous findings of the physicists for the restricted case of a product Bernoulli measure. However we show that a different behavior appears when the initial domain distribution is in the attraction domain of a α-stable law. All the above results actually follow from a more general result which says that the low temperature dynamics of the East model is very well described by that of a certain hierarchical coalescence process, a probabilistic object which can be viewed as a hierarchical sequence of suitably linked coalescence processes and whose asymptotic behavior has been recently studied in Faggionato et al. (Universality in one dimensional hierarchical 1059 coalescence processes. Preprint, 2011).

  18. Exact Tests for the Rasch Model via Sequential Importance Sampling

    ERIC Educational Resources Information Center

    Chen, Yuguo; Small, Dylan

    2005-01-01

    Rasch proposed an exact conditional inference approach to testing his model but never implemented it because it involves the calculation of a complicated probability. This paper furthers Rasch's approach by (1) providing an efficient Monte Carlo methodology for accurately approximating the required probability and (2) illustrating the usefulness…

  19. Plasma pyridoxal phosphate and pyridoxic acid and their relationship to plasma homocysteine in a representative sample of British men and women aged 65 years and over.

    PubMed

    Bates, C J; Pentieva, K D; Prentice, A; Mansoor, M A; Finch, S

    1999-03-01

    Concentrations of pyridoxal phosphate and pyridoxic acid were measured in fasting plasma samples from British men and women aged 65 years and over, participating in a National Diet and Nutrition Survey during 1994-5, selected to be representative of the population of mainland Britain. In this population, the concentration of pyridoxal phosphate declined, whereas pyridoxic acid rose, with increasing age and frailty; however, both status indicators were strongly and directly (with a positive coefficient) correlated with estimates of vitamin B6 intake. This was little affected by the inclusion of food energy and protein intakes in the model. Forty-eight percent of the participants living in the community and 75% of those living in institutions had plasma pyridoxal phosphate concentrations below a range considered normal from other studies. In a univariate regression model, plasma pyridoxal phosphate concentrations were inversely correlated with plasma homocysteine concentrations, consistent with the hypothesis that vitamin B6 status may influence plasma homocysteine levels, and hence vascular disease risk. However, this relationship was partly attenuated in a multiple regression model including age, sex, domicile and biochemical status indices, including those of folate and vitamin B12. There was evidence that plasma pyridoxal phosphate was sensitive to metabolic conditions associated with inflammation and the acute-phase reaction, and that plasma pyridoxic acid was sensitive to renal function. Thus, neither index is an ideal predictor of vitamin B6 status in older people, unless these confounding factors are allowed for. Since poor vitamin B6 status may have health implications, e.g. for immune function, cognition, and for essential intermediary metabolic pathways in older people, it needs to be investigated as a possible public health problem.

  20. Accelerated rare event sampling: Refinement and Ising model analysis

    NASA Astrophysics Data System (ADS)

    Yevick, David; Lee, Yong Hwan

    In this paper, a recently introduced accelerated sampling technique [D. Yevick, Int. J. Mod. Phys. C 27, 1650041 (2016)] for constructing transition matrices is further developed and applied to a two-dimensional 32×32 Ising spin system. By permitting backward displacements up to a certain limit for each forward step while evolving the system to first higher and then lower energies within a restricted interval that is steadily displaced toward zero temperature as the computation proceeds, accuracy can be greatly enhanced. Simultaneously, the elements obtained from numerous independent calculations are collected in a single transition matrix. The relative accuracy of this novel method is established through a comparison to a transition matrix procedure based on the Metropolis algorithm in which the temperature is appropriately varied during the calculation and the results interpreted in terms of the distribution of realizations over both energy and magnetization.

  1. Rasch-modeling the Portuguese SOCRATES in a clinical sample.

    PubMed

    Lopes, Paulo; Prieto, Gerardo; Delgado, Ana R; Gamito, Pedro; Trigo, Hélder

    2010-06-01

    The Stages of Change Readiness and Treatment Eagerness Scale (SOCRATES) assesses motivation for treatment in the drug-dependent population. The development of adequate measures of motivation is needed in order to properly understand the role of this construct in rehabilitation. This study probed the psychometric properties of the SOCRATES in the Portuguese population by means of the Rasch Rating Scale Model, which allows the conjoint measurement of items and persons. The participants were 166 substance abusers under treatment for their addiction. Results show that the functioning of the five response categories is not optimal; our re-analysis indicates that a three-category system is the most appropriate one. By using this response category system, both model fit and estimation accuracy are improved. The discussion takes into account other factors such as item format and content in order to make suggestions for the development of better motivation-for-treatment scales.

  2. Prevalence of Hearing Loss Among a Representative Sample of Canadian Children and Adolescents, 3 to 19 Years of Age

    PubMed Central

    Michaud, David; McNamee, James; Fitzpatrick, Elizabeth; Ramage-Morin, Pamela; Beauregard, Yves

    2017-01-01

    Objectives: There are no nationally representative hearing loss (HL) prevalence data available for Canadian youth using direct measurements. The present study objectives were to estimate national prevalence of HL using audiometric pure-tone thresholds (0.5 to 8 kHz) and or distortion product otoacoustic emissions (DPOAEs) for children and adolescents, aged 3 to 19 years. Design: This cross-sectional population-based study presents findings from the 2012/2013 Canadian Health Measures Survey, entailing an in-person household interview and hearing measurements conducted in a mobile examination clinic. The initial study sample included 2591 participants, aged 3 to 19 years, representing 6.5 million Canadians (3.3 million males). After exclusions, subsamples consisted of 2434 participants, aged 3 to 19 years and 1879 participants, aged 6 to 19 years, with valid audiometric results. Eligible participants underwent otoscopic examination, tympanometry, DPOAE, and audiometry. HL was defined as a pure-tone average >20 dB for 6- to 18-year olds and ≥26 dB for 19-year olds, for one or more of the following: four-frequency (0.5, 1, 2, and 4 kHz) pure-tone average, high-frequency (3, 4, 6, and 8 kHz) pure-tone average, and low-frequency (0.5, 1, and 2 kHz) pure-tone average. Mild HL was defined as >20 to 40 dB (6- to 18-year olds) and ≥26 to 40 dB (19-year olds). Moderate or worse HL was defined as >40 dB (6- to 19-year olds). HL in 3- to 5-year olds (n = 555) was defined as absent DPOAEs as audiometry was not conducted. Self-reported HL was evaluated using the Health Utilities Index Mark 3 hearing questions. Results: The primary study outcome indicates that 7.7% of Canadian youth, aged 6 to 19, had any HL, for one or more pure-tone average. Four-frequency pure-tone average and high-frequency pure-tone average HL prevalence was 4.7 and 6.0%, respectively, whereas 5.8% had a low-frequency pure-tone average HL. Significantly more children/adolescents had unilateral HL

  3. 12 CFR Appendix B to Part 230 - Model Clauses and Sample Forms

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 4 2014-01-01 2014-01-01 false Model Clauses and Sample Forms B Appendix B to... SYSTEM (CONTINUED) TRUTH IN SAVINGS (REGULATION DD) Pt. 230, App. B Appendix B to Part 230—Model Clauses and Sample Forms Table of contents B-1—Model Clauses for Account Disclosures (Section 230.4(b))...

  4. 12 CFR Appendix B to Part 230 - Model Clauses and Sample Forms

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 4 2013-01-01 2013-01-01 false Model Clauses and Sample Forms B Appendix B to... SYSTEM (CONTINUED) TRUTH IN SAVINGS (REGULATION DD) Pt. 230, App. B Appendix B to Part 230—Model Clauses and Sample Forms Table of contents B-1—Model Clauses for Account Disclosures (Section 230.4(b))...

  5. 12 CFR Appendix B to Part 230 - Model Clauses and Sample Forms

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 4 2012-01-01 2012-01-01 false Model Clauses and Sample Forms B Appendix B to... SYSTEM (CONTINUED) TRUTH IN SAVINGS (REGULATION DD) Pt. 230, App. B Appendix B to Part 230—Model Clauses and Sample Forms Table of contents B-1—Model Clauses for Account Disclosures (Section 230.4(b))...

  6. Effect of gravity on the erosion of model samples

    NASA Astrophysics Data System (ADS)

    Larionov, G. A.; Bushueva, O. G.; Dobrovol'skaya, N. G.; Kiryukhina, Z. P.; Krasnov, S. F.; Litvin, L. F.

    2015-07-01

    The article is devoted to the theoretical analysis and experimental investigation of the bottom and lateral erosion in shallow flows on slopes. The analysis of the ratio between the forces detaching and retaining a soil particle has showed that the erosion of the bed sidewall exceeds manifold the erosion of the bottom at the flow velocity close to the threshold value. When the flow velocity increases, the differences in the rate of erosion between the bottom and the sidewalls of the rill are leveled. The rate of sidewall erosion strongly depends on the slope of rill sides. The experimental studies of the effect of the sample surface inclination have completely confirmed the theoretical conclusions. It should be kept in mind that the lateral erosion under natural conditions is also limited by the laws of hydraulics. When the rill bed is widened due to the lateral erosion, the flow width increases and, hence, its velocity decreases to below the threshold value, which stops the erosion of the bed.

  7. Assessment of Borderline Personality Features in Population Samples: Is the Personality Assessment Inventory-Borderline Features Scale Measurement Invariant across Sex and Age?

    ERIC Educational Resources Information Center

    De Moor, Marleen H. M.; Distel, Marijn A.; Trull, Timothy J.; Boomsma, Dorret I.

    2009-01-01

    Borderline personality disorder (BPD) is more often diagnosed in women than in men, and symptoms tend to decline with age. Using a large community sample, the authors investigated whether sex and age differences in four main features of BPD, measured with the "Personality Assessment Inventory-Borderline Features" scale (PAI-BOR; Morey,…

  8. Modeling of aging in plutonium by molecular dynamics

    NASA Astrophysics Data System (ADS)

    Pochet, P.

    2003-04-01

    The origin of aging in plutonium lies in the extra formation of defects due to self-decay of 239Pu. The modeling of the formation of these defects is achieved by molecular dynamics (MD). In this work a simple EAM potential has been used to study defects formation in fcc plutonium and a 2 keV cascade is analyzed. A large pressure wave is generated around the cascade core. In the used MD code the pressure wave is not absorbed at the box boundaries and due to the periodic boundary conditions, the use of a very large box is crucial in order to avoid interaction of the cascade with itself. More than 800 000 atoms are needed to deal with this small 2 keV cascade without any artifacts. This effect comes from the very low bulk modulus of fcc Pu. The relative long time to achieve the annealing is also connected to the bulk modulus. These results are discussed in terms of large pressure wave: alloying effects are predicted using that viewpoint.

  9. Red blood cells open promising avenues for longitudinal studies of ageing in laboratory, non-model and wild animals.

    PubMed

    Stier, Antoine; Reichert, Sophie; Criscuolo, Francois; Bize, Pierre

    2015-11-01

    Ageing is characterized by a progressive deterioration of multiple physiological and molecular pathways, which impair organismal performance and increase risks of death with advancing age. Hence, ageing studies must identify physiological and molecular pathways that show signs of age-related deterioration, and test their association with the risk of death and longevity. This approach necessitates longitudinal sampling of the same individuals, and therefore requires a minimally invasive sampling technique that provides access to the larger spectrum of physiological and molecular pathways that are putatively associated with ageing. The present paper underlines the interest in using red blood cells (RBCs) as a promising target for longitudinal studies of ageing in vertebrates. RBCs provide valuable information on the following six pathways: cell maintenance and turnover (RBC number, size, and heterogeneity), glucose homeostasis (RBC glycated haemoglobin), oxidative stress parameters, membrane composition and integrity, mitochondrial functioning, and telomere dynamics. The last two pathways are specific to RBCs of non-mammalian species, which possess a nucleus and functional mitochondria. We present the current knowledge about RBCs and age-dependent changes in these pathways in non-model and wild species that are especially suitable to address questions related to ageing using longitudinal studies. We discuss how the different pathways relate with survival and lifespan and give information on their genetic and environmental determinants to appraise their evolutionary potential.

  10. Characterizing cognitive aging in humans with links to animal models

    PubMed Central

    Alexander, Gene E.; Ryan, Lee; Bowers, Dawn; Foster, Thomas C.; Bizon, Jennifer L.; Geldmacher, David S.; Glisky, Elizabeth L.

    2012-01-01

    With the population of older adults expected to grow rapidly over the next two decades, it has become increasingly important to advance research efforts to elucidate the mechanisms associated with cognitive aging, with the ultimate goal of developing effective interventions and prevention therapies. Although there has been a vast research literature on the use of cognitive tests to evaluate the effects of aging and age-related neurodegenerative disease, the need for a set of standardized measures to characterize the cognitive profiles specific to healthy aging has been widely recognized. Here we present a review of selected methods and approaches that have been applied in human research studies to evaluate the effects of aging on cognition, including executive function, memory, processing speed, language, and visuospatial function. The effects of healthy aging on each of these cognitive domains are discussed with examples from cognitive/experimental and clinical/neuropsychological approaches. Further, we consider those measures that have clear conceptual and methodological links to tasks currently in use for non-human animal studies of aging, as well as those that have the potential for translation to animal aging research. Having a complementary set of measures to assess the cognitive profiles of healthy aging across species provides a unique opportunity to enhance research efforts for cross-sectional, longitudinal, and intervention studies of cognitive aging. Taking a cross-species, translational approach will help to advance cognitive aging research, leading to a greater understanding of associated neurobiological mechanisms with the potential for developing effective interventions and prevention therapies for age-related cognitive decline. PMID:22988439

  11. Age models for peat deposits on the basis of coupled lead-210 and radiocarbon data.

    NASA Astrophysics Data System (ADS)

    Piotrowska, Natalia; de Vleeschouwer, François; Sikorski, Jarosław; Sensuła, Barbara; Michczyński, Adam; Fiałkiewicz-Kozieł, Barbara; Palowski, Bernard

    2010-05-01

    The study presents three examples of age-model construction based on the results of 210Pb and 14C dating methods applied to peat deposits. The three sites are ombrotrophic peat bogs: the Misten (Belgium), Slowinskie Bloto (N Poland) and Puscizna Mala (S Poland). All sites have been subjected to multiproxy studies aimed at reconstructing paleoenvironment and human activity, covering the last 1500, 1300 and 1800 years, respectively (De Vleeschouwer et al. 2009A, 2009B, in prep., Fialkiewicz-Koziel, ongoing PhD). A detailed comparison between 210Pb and post-bomb 14C results in the Misten bog has also been carried out by Piotrowska et al. (2009). In all cores, the 210Pb activity was calculated using 210Po and 208Po activities after acid-extraction from bulk samples, subsequent deposition on silver discs and measurements by alpha spectrometry. Unsupported 210Pb was detected until 35cm in Slowinskie Bloto, 15cm in the Misten and 19cm in Puscizna Mala. Constant Rate of Supply (CRS) model was then applied to compute ages of each 1-cm core interval. For the Misten and Slowinskie Bloto, radiocarbon measurements were performed on selected aboveground plant macrofossils, mainly Sphagnum spp. or Calluna vulgaris, Erica tetralix, and Andromeda polyfolia. Radiocarbon ages were determined using accelerator mass spectrometry (AMS) after acid-alkali-acid wash, combustion, purification of carbon dioxide and graphitisation. For Puscizna Mala bulk samples were dated after chemical preparation of benzene for liquid scintillation counting (LSC) or CO2 for gas proportional counting (GPC). Radiocarbon calibration was undertaken using the Intcal04 calibration curve and OxCal 4 software. As a priori information the 210Pb-derived ages were used in a P_Sequence model (Bronk Ramsey, 2008). A number of dates characterized by low agreement with stratigraphical order had to be considered as outliers and rejected from the final age model. For building a continuous age models a non-linear approach

  12. Continuous Age-Structured Model for Bovine Tuberculosis in African buffalo

    NASA Astrophysics Data System (ADS)

    Anguelov, R.; Kojouharov, H.

    2009-10-01

    The paper deals with a model of the spread of bovine tuberculosis in the buffalo population in the Kruger National Park in South Africa. The model uses continuous age structure and it is formulated in terms of partial differential equations using eight epidemiological classes (compartments). More precisely, the age density for each class at time t satisfies a one way wave equation, where the age is the space variable. The continuous age model discussed here is derived from a 2006 age groups model by P. C. Cross and W. M. Getz.

  13. Rates of Nonsuicidal Self-Injury in Youth: Age, Sex, and Behavioral Methods in a Community Sample

    PubMed Central

    Hankin, Benjamin L.; Young, Jami F.; Abela, John R. Z.

    2012-01-01

    OBJECTIVE: The goal was to assess the rate and behavioral methods of nonsuicidal self-injury (NSSI) in a community sample of youth and examine effects of age and sex. METHODS: Youth in the third, sixth, and ninth grades (ages 7–16) at schools in the community were invited to participate in a laboratory study. A total of 665 youth (of 1108 contacted; 60% participation rate) were interviewed about NSSI over their lifetime via the Self-Injurious Thoughts and Behaviors Interview. RESULTS: Overall, 53 (8.0%) of the 665 youth reported engaging in NSSI; 9.0% of girls and 6.7% of boys reported NSSI engagement; 7.6% of third-graders, 4.0% of sixth-graders, and 12.7% of ninth-graders reported NSSI engagement. There was a significant grade by gender interaction; girls in the ninth grade (19%) reported significantly greater rates of NSSI than ninth-grade boys (5%). Behavioral methods of NSSI differed by gender. Girls reported cutting and carving skin most often, whereas boys reported hitting themselves most often. Finally, 1.5% of youth met some criteria for the proposed fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) diagnosis of NSSI. CONCLUSIONS: Children and adolescents engage in NSSI. Ninth-grade girls seem most at risk, as they engage in NSSI at 3 times the rate of boys. Behavioral methods of NSSI also vary by grade and gender. As possible inclusion of an NSSI diagnosis in the fifth edition of the DSM-5 draws near, it is essential to better understand NSSI engagement across development and gender. PMID:22689875

  14. A ternary age-mixing model to explain contaminant occurrence in a deep supply well

    USGS Publications Warehouse

    Jurgens, Bryant; Bexfield, Laura M.; Eberts, Sandra

    2014-01-01

    The age distribution of water from a public-supply well in a deep alluvial aquifer was estimated and used to help explain arsenic variability in the water. The age distribution was computed using a ternary mixing model that combines three lumped parameter models of advection-dispersion transport of environmental tracers, which represent relatively recent recharge (post- 1950s) containing volatile organic compounds (VOCs), old intermediate depth groundwater (about 6500 years) that was free of drinking-water contaminants, and very old, deep groundwater (more than 21,000 years) containing arsenic above the USEPA maximum contaminant level of 10 µg/L. The ternary mixing model was calibrated to tritium, chloroflorocarbon-113, and carbon-14 (14C) concentrations that were measured in water samples collected on multiple occasions. Variability in atmospheric 14C over the past 50,000 years was accounted for in the interpretation of 14C as a tracer. Calibrated ternary models indicate the fraction of deep, very old groundwater entering the well varies substantially throughout the year and was highest following long periods of nonoperation or infrequent operation, which occured during the winter season when water demand was low. The fraction of young water entering the well was about 11% during the summer when pumping peaked to meet water demand and about 3% to 6% during the winter months. This paper demonstrates how collection of multiple tracers can be used in combination with simplified models of fluid flow to estimate the age distribution and thus fraction of contaminated groundwater reaching a supply well under different pumping conditions.

  15. A ternary age-mixing model to explain contaminant occurrence in a deep supply well.

    PubMed

    Jurgens, Bryant C; Bexfield, Laura M; Eberts, Sandra M

    2014-09-01

    The age distribution of water from a public-supply well in a deep alluvial aquifer was estimated and used to help explain arsenic variability in the water. The age distribution was computed using a ternary mixing model that combines three lumped parameter models of advection-dispersion transport of environmental tracers, which represent relatively recent recharge (post-1950s) containing volatile organic compounds (VOCs), old intermediate depth groundwater (about 6500 years) that was free of drinking-water contaminants, and very old, deep groundwater (more than 21,000 years) containing arsenic above the USEPA maximum contaminant level of 10 µg/L. The ternary mixing model was calibrated to tritium, chloroflorocarbon-113, and carbon-14 (14C) concentrations that were measured in water samples collected on multiple occasions. Variability in atmospheric 14C over the past 50,000 years was accounted for in the interpretation of (14) C as a tracer. Calibrated ternary models indicate the fraction of deep, very old groundwater entering the well varies substantially throughout the year and was highest following long periods of nonoperation or infrequent operation, which occured during the winter season when water demand was low. The fraction of young water entering the well was about 11% during the summer when pumping peaked to meet water demand and about 3% to 6% during the winter months. This paper demonstrates how collection of multiple tracers can be used in combination with simplified models of fluid flow to estimate the age distribution and thus fraction of contaminated groundwater reaching a supply well under different pumping conditions.

  16. A Ternary Age-Mixing Model to Explain Contaminant Occurrence in a Deep Supply Well

    PubMed Central

    Jurgens, Bryant C; Bexfield, Laura M; Eberts, Sandra M

    2014-01-01

    The age distribution of water from a public-supply well in a deep alluvial aquifer was estimated and used to help explain arsenic variability in the water. The age distribution was computed using a ternary mixing model that combines three lumped parameter models of advection-dispersion transport of environmental tracers, which represent relatively recent recharge (post-1950s) containing volatile organic compounds (VOCs), old intermediate depth groundwater (about 6500 years) that was free of drinking-water contaminants, and very old, deep groundwater (more than 21,000 years) containing arsenic above the USEPA maximum contaminant level of 10 µg/L. The ternary mixing model was calibrated to tritium, chloroflorocarbon-113, and carbon-14 (14C) concentrations that were measured in water samples collected on multiple occasions. Variability in atmospheric 14C over the past 50,000 years was accounted for in the interpretation of 14C as a tracer. Calibrated ternary models indicate the fraction of deep, very old groundwater entering the well varies substantially throughout the year and was highest following long periods of nonoperation or infrequent operation, which occured during the winter season when water demand was low. The fraction of young water entering the well was about 11% during the summer when pumping peaked to meet water demand and about 3% to 6% during the winter months. This paper demonstrates how collection of multiple tracers can be used in combination with simplified models of fluid flow to estimate the age distribution and thus fraction of contaminated groundwater reaching a supply well under different pumping conditions. PMID:24597520

  17. The Stroop Color-Word Test: Influence of Age, Sex, and Education; and Normative Data for a Large Sample Across the Adult Age Range

    ERIC Educational Resources Information Center

    Van der Elst, Wim; Van Boxtel, Martin P. J.; Van Breukelen, Gerard J. P.; Jolles, Jelle

    2006-01-01

    The Stroop Color-Word Test was administered to 1,856 cognitively screened, healthy Dutch-speaking participants aged 24 to 81 years. The effects of age, gender, and education on Stroop test performance were investigated to adequately stratify the normative data. The results showed that especially the speed-dependent Stroop scores (time to complete…

  18. Closed-population capture-recapture modeling of samples drawn one at a time.

    PubMed

    Barker, Richard J; Schofield, Matthew R; Wright, Janine A; Frantz, Alain C; Stevens, Chris

    2014-12-01

    Motivated by field sampling of DNA fragments, we describe a general model for capture-recapture modeling of samples drawn one at a time in continuous-time. Our model is based on Poisson sampling where the sampling time may be unobserved. We show that previously described models correspond to partial likelihoods from our Poisson model and their use may be justified through arguments concerning S- and Bayes-ancillarity of discarded information. We demonstrate a further link to continuous-time capture-recapture models and explain observations that have been made about this class of models in terms of partial ancillarity. We illustrate application of our models using data from the European badger (Meles meles) in which genotyping of DNA fragments was subject to error.

  19. How does observation uncertainty influence which stream water samples are most informative for model calibration?

    NASA Astrophysics Data System (ADS)

    Wang, Ling; van Meerveld, Ilja; Seibert, Jan

    2016-04-01

    Streamflow isotope samples taken during rainfall-runoff events are very useful for multi-criteria model calibration because they can help decrease parameter uncertainty and improve internal model consistency. However, the number of samples that can be collected and analysed is often restricted by practical and financial constraints. It is, therefore, important to choose an appropriate sampling strategy and to obtain samples that have the highest information content for model calibration. We used the Birkenes hydrochemical model and synthetic rainfall, streamflow and isotope data to explore which samples are most informative for model calibration. Starting with error-free observations, we investigated how many samples are needed to obtain a certain model fit. Based on different parameter sets, representing different catchments, and different rainfall events, we also determined which sampling times provide the most informative data for model calibration. Our results show that simulation performance for models calibrated with the isotopic data from two intelligently selected samples was comparable to simulations based on isotopic data for all 100 time steps. The models calibrated with the intelligently selected samples also performed better than the model calibrations with two benchmark sampling strategies (random selection and selection based on hydrologic information). Surprisingly, samples on the rising limb and at the peak were less informative than expected and, generally, samples taken at the end of the event were most informative. The timing of the most informative samples depends on the proportion of different flow components (baseflow, slow response flow, fast response flow and overflow). For events dominated by baseflow and slow response flow, samples taken at the end of the event after the fast response flow has ended were most informative; when the fast response flow was dominant, samples taken near the peak were most informative. However when overflow

  20. Microwave-Assisted Sample Treatment in a Fully Automated Flow-Based Instrument: Oxidation of Reduced Technetium Species in the Analysis of Total Technetium-99 in Caustic Aged Nuclear Waste Samples

    SciTech Connect

    Egorov, Oleg B.; O'Hara, Matthew J.; Grate, Jay W.

    2004-07-15

    An automated flow-based instrument for microwave-assisted treatment of liquid samples has been developed and characterized. The instrument utilizes a flow-through reaction vessel design that facilitates the addition of multiple reagents during sample treatment, removal of the gaseous reaction products, and enables quantitative removal of liquids from the reaction vessel for carryover-free operations. Matrix modification and speciation control chemistries that are required for the radiochemical determination of total 99Tc in caustic aged nuclear waste samples have been investigated. A rapid and quantitative oxidation procedure using peroxydisulfate in acidic solution was developed to convert reduced technetium species to pertechnetate in samples with high content of reducing organics. The effectiveness of the automated sample treatment procedures has been validated in the radiochemical analysis of total 99Tc in caustic aged nuclear waste matrixes from the Hanford site.

  1. Developmental emergence and functionality of Sehnsucht (life longings): the sample case of involuntary childlessness in middle-aged women.

    PubMed

    Kotter-Grühn, Dana; Scheibe, Susanne; Blanchard-Fields, Fredda; Baltes, Paul B

    2009-09-01

    Sehnsucht (life longings), the intense desire for optimal (utopian) states of life that are remote or unattainable, was recently introduced into life-span psychology as a concept of self-regulation (P. B. Baltes, 2008; S. Scheibe, A. M. Freund, & P. B. Baltes, 2007). The authors propose that as a compensatory strategy to deal with nonrealizability and loss, life longings may develop out of blocked goals. Individuals would cease to invest behavioral effort into its attainment and instead maintain the goal target in imagination. In a sample of 168 middle-aged childless women, the present study investigated the circumstances under which the wish for children emerges as a goal or life longing and whether the representation of the wish for children as a life longing is beneficial for well-being. The wish for children was expressed as a goal when participants rated this wish as currently intense and attainable. In contrast, it was expressed as a life longing when participants rated it as highly intense and long-standing. The pursuit of the wish for children as a life longing was positively related to well-being only when participants had high control over the experience of this life longing and when other self-regulation strategies (goal adjustment) failed.

  2. The short-lived African turquoise killifish: an emerging experimental model for ageing

    PubMed Central

    Kim, Yumi; Nam, Hong Gil; Valenzano, Dario Riccardo

    2016-01-01

    ABSTRACT Human ageing is a fundamental biological process that leads to functional decay, increased risk for various diseases and, ultimately, death. Some of the basic biological mechanisms underlying human ageing are shared with other organisms; thus, animal models have been invaluable in providing key mechanistic and molecular insights into the common bases of biological ageing. In this Review, we briefly summarise the major applications of the most commonly used model organisms adopted in ageing research and highlight their relevance in understanding human ageing. We compare the strengths and limitations of different model organisms and discuss in detail an emerging ageing model, the short-lived African turquoise killifish. We review the recent progress made in using the turquoise killifish to study the biology of ageing and discuss potential future applications of this promising animal model. PMID:26839399

  3. The short-lived African turquoise killifish: an emerging experimental model for ageing.

    PubMed

    Kim, Yumi; Nam, Hong Gil; Valenzano, Dario Riccardo

    2016-02-01

    Human ageing is a fundamental biological process that leads to functional decay, increased risk for various diseases and, ultimately, death. Some of the basic biological mechanisms underlying human ageing are shared with other organisms; thus, animal models have been invaluable in providing key mechanistic and molecular insights into the common bases of biological ageing. In this Review, we briefly summarise the major applications of the most commonly used model organisms adopted in ageing research and highlight their relevance in understanding human ageing. We compare the strengths and limitations of different model organisms and discuss in detail an emerging ageing model, the short-lived African turquoise killifish. We review the recent progress made in using the turquoise killifish to study the biology of ageing and discuss potential future applications of this promising animal model.

  4. 12 CFR Appendix B to Part 1030 - Model Clauses and Sample Forms

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 8 2013-01-01 2013-01-01 false Model Clauses and Sample Forms B Appendix B to.... 1030, App. B Appendix B to Part 1030—Model Clauses and Sample Forms Table of Contents B-1—Model Clauses for Account Disclosures (Section 1030.4(b)) B-2—Model Clauses for Change in Terms (Section...

  5. 12 CFR Appendix B to Part 1030 - Model Clauses and Sample Forms

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 8 2012-01-01 2012-01-01 false Model Clauses and Sample Forms B Appendix B to.... 1030, App. B Appendix B to Part 1030—Model Clauses and Sample Forms Table of Contents B-1—Model Clauses for Account Disclosures (Section 1030.4(b)) B-2—Model Clauses for Change in Terms (Section...

  6. 12 CFR Appendix B to Part 230 - Model Clauses and Sample Forms

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 12 Banks and Banking 3 2011-01-01 2011-01-01 false Model Clauses and Sample Forms B Appendix B to... SYSTEM TRUTH IN SAVINGS (REGULATION DD) Pt. 230, App. B Appendix B to Part 230—Model Clauses and Sample Forms Table of contents B-1—Model Clauses for Account Disclosures (Section 230.4(b)) B-2—Model...

  7. An agent-based computational model for tuberculosis spreading on age-structured populations

    NASA Astrophysics Data System (ADS)

    Graciani Rodrigues, C. C.; Espíndola, Aquino L.; Penna, T. J. P.

    2015-06-01

    In this work we present an agent-based computational model to study the spreading of the tuberculosis (TB) disease on age-structured populations. The model proposed is a merge of two previous models: an agent-based computational model for the spreading of tuberculosis and a bit-string model for biological aging. The combination of TB with the population aging, reproduces the coexistence of health states, as seen in real populations. In addition, the universal exponential behavior of mortalities curves is still preserved. Finally, the population distribution as function of age shows the prevalence of TB mostly in elders, for high efficacy treatments.

  8. 12 CFR Appendix B to Part 707 - Model Clauses and Sample Forms

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 7 2014-01-01 2014-01-01 false Model Clauses and Sample Forms B Appendix B to...) Account Disclosures) B-10—Sample Form (Periodic Statement) B-11—Sample Form (Rate and Fee Schedule) B-12... terms, leaving the decision instead to each credit union's board of directors. 12 CFR 204.2(c)(2)....

  9. Accuracy of Parameter Estimation in Gibbs Sampling under the Two-Parameter Logistic Model.

    ERIC Educational Resources Information Center

    Kim, Seock-Ho; Cohen, Allan S.

    The accuracy of Gibbs sampling, a Markov chain Monte Carlo procedure, was considered for estimation of item and ability parameters under the two-parameter logistic model. Memory test data were analyzed to illustrate the Gibbs sampling procedure. Simulated data sets were analyzed using Gibbs sampling and the marginal Bayesian method. The marginal…

  10. Analysis of age-at-death estimation using data from a new, modern autopsy sample--part I: pubic bone.

    PubMed

    Hartnett, Kristen M

    2010-09-01

    This research tests the accuracy of age estimation from the pubic bone. Specimens were collected from decedents of known age, sex, and race at the Forensic Science Center (FSC) in Phoenix, Arizona. The collection consists of pubic bones and fourth rib ends from 419 males and 211 females, ranging in age from 18 to 99. Age-at-death was estimated by three observers using the Suchey-Brooks method. The correlation results indicate that there are significant differences in the observed versus actual ages (r = 0.68169, p < 0.001) and that there are significant interobserver differences. No significant differences were found in the intra-observer tests. The FSC pubic bones were sorted based on morphology without knowing age. New descriptions and age ranges were created. A phase seven was described and is comprised of males and females over 70 years of age-at-death.

  11. Urban groundwater age modeling under unconfined condition - Impact of underground structures on groundwater age: Evidence of a piston effect

    NASA Astrophysics Data System (ADS)

    Attard, Guillaume; Rossier, Yvan; Eisenlohr, Laurent

    2016-04-01

    In this paper, underground structures are shown to have a major influence on the groundwater mean age distribution described as a dispersive piston effect. Urban underground development does not occur without impacts on subsoil resources. In particular, groundwater resources can be vulnerable and generate disturbances when this space is exploited. Groundwater age spatial distribution data are fundamental for resource management as it can provide operational sustainability indicators. However, the application of groundwater age modeling is neglected regarding the potential effect of underground structures in urban areas. A three dimensional modeling approach was conducted to quantify the impact of two underground structures: (1) an impervious structure and (2) a draining structure. Both structures are shown to cause significant mixing processes occurring between shallow and deeper aquifers. The design technique used for draining structures is shown to have the greatest impact, generating a decrease in mean age of more than 80% under the structure. Groundwater age modeling is shown to be relevant for highlighting the role played by underground structures in advective-dispersive flows in urban areas.

  12. Epistatic Module Detection for Case-Control Studies: A Bayesian Model with a Gibbs Sampling Strategy

    PubMed Central

    Tang, Wanwan; Wu, Xuebing; Jiang, Rui; Li, Yanda

    2009-01-01

    The detection of epistatic interactive effects of multiple genetic variants on the susceptibility of human complex diseases is a great challenge in genome-wide association studies (GWAS). Although methods have been proposed to identify such interactions, the lack of an explicit definition of epistatic effects, together with computational difficulties, makes the development of new methods indispensable. In this paper, we introduce epistatic modules to describe epistatic interactive effects of multiple loci on diseases. On the basis of this notion, we put forward a Bayesian marker partition model to explain observed case-control data, and we develop a Gibbs sampling strategy to facilitate the detection of epistatic modules. Comparisons of the proposed approach with three existing methods on seven simulated disease models demonstrate the superior performance of our approach. When applied to a genome-wide case-control data set for Age-related Macular Degeneration (AMD), the proposed approach successfully identifies two known susceptible loci and suggests that a combination of two other loci—one in the gene SGCD and the other in SCAPER—is associated with the disease. Further functional analysis supports the speculation that the interaction of these two genetic variants may be responsible for the susceptibility of AMD. When applied to a genome-wide case-control data set for Parkinson's disease, the proposed method identifies seven suspicious loci that may contribute independently to the disease. PMID:19412524

  13. Techniques for Down-Sampling a Measured Surface Height Map for Model Validation

    NASA Technical Reports Server (NTRS)

    Sidick, Erkin

    2012-01-01

    This software allows one to down-sample a measured surface map for model validation, not only without introducing any re-sampling errors, but also eliminating the existing measurement noise and measurement errors. The software tool of the current two new techniques can be used in all optical model validation processes involving large space optical surfaces

  14. GY SAMPLING THEORY AND GEOSTATISTICS: ALTERNATE MODELS OF VARIABILITY IN CONTINUOUS MEDIA

    EPA Science Inventory



    In the sampling theory developed by Pierre Gy, sample variability is modeled as the sum of a set of seven discrete error components. The variogram used in geostatisties provides an alternate model in which several of Gy's error components are combined in a continuous mode...

  15. Application of the Tripartite Model to a Complicated Sample of Residential Youth with Externalizing Problems

    ERIC Educational Resources Information Center

    Chin, Eu Gene; Ebesutani, Chad; Young, John

    2013-01-01

    The tripartite model of anxiety and depression has received strong support among child and adolescent populations. Clinical samples of children and adolescents in these studies, however, have usually been referred for treatment of anxiety and depression. This study investigated the fit of the tripartite model with a complicated sample of…

  16. Organophosphate Insecticide Metabolites in Prenatal and Childhood Urine Samples and Intelligence Scores at 6 Years of Age: Results from the Mother–Child PELAGIE Cohort (France)

    PubMed Central

    Cartier, Chloé; Warembourg, Charline; Le Maner-Idrissi, Gaïd; Lacroix, Agnès; Rouget, Florence; Monfort, Christine; Limon, Gwendolina; Durand, Gaël; Saint-Amour, Dave; Cordier, Sylvaine; Chevrier, Cécile

    2015-01-01

    Background: Several studies suggest that exposure to organophosphate insecticides (OP) during pregnancy impairs neurodevelopment in children. Objectives: We evaluated associations between biomarkers of prenatal and postnatal OP exposure and cognitive function of 6-year-olds in a French longitudinal birth cohort. Methods: In 2002–2006, the PELAGIE mother–child cohort enrolled pregnant women from Brittany. For a random subcohort, we measured nonspecific dialkylphosphate metabolites (DAP) of OP in one maternal urine sample, collected before 19 weeks’ gestation, and in one urine sample collected from their 6-year-old children. Six subtests of the Wechsler Intelligence Scale for Children, 4th edition (WISC-IV) were administered when the children were 6 years of age to evaluate cognitive function (n = 231). Linear regression models controlling for factors including maternal intelligence and the Home Observation for Measurement of the Environment score were used. Results: WISC-IV scores were not significantly associated with prenatal or childhood total DAP metabolites. WISC verbal comprehension score was significantly higher in association with the highest maternal urinary concentrations of diethylphosphate (DE) metabolites (5.5; 95% CI: 0.8, 10.3 for > 13.2 nmol/L vs. < LOQ), whereas WISC working memory score was significantly lower in association with the highest urinary concentrations of DE metabolites at age 6 years (–3.6; 95% CI: –7.8, –0.6 for > 11.1 nmol/L vs. < LOD). Conclusion: We found no evidence that prenatal OP exposure adversely affected cognitive function in 6-year-olds, perhaps because of the population’s socioeconomic status, which was higher than in previous studies, though other causal and noncausal explanations are also possible. The negative association between WISC score and concurrent DE urinary concentrations requires replication by longitudinal studies investigating childhood OP exposure. Citation: Cartier C, Warembourg C, Le Maner

  17. Asteroid age distributions determined by space weathering and collisional evolution models

    NASA Astrophysics Data System (ADS)

    Willman, Mark; Jedicke, Robert

    2011-01-01

    We provide evidence of consistency between the dynamical evolution of main belt asteroids and their color evolution due to space weathering. The dynamical age of an asteroid's surface (Bottke, W.F., Durda, D.D., Nesvorný, D., Jedicke, R., Morbidelli, A., Vokrouhlický, D., Levison, H. [2005]. Icarus 175 (1), 111-140; Nesvorný, D., Jedicke, R., Whiteley, R.J., Ivezić, Ž. [2005]. Icarus 173, 132-152) is the time since its last catastrophic disruption event which is a function of the object's diameter. The age of an S-complex asteroid's surface may also be determined from its color using a space weathering model (e.g. Willman, M., Jedicke, R., Moskovitz, N., Nesvorný, D., Vokrouhlický, D., Mothé-Diniz, T. [2010]. Icarus 208, 758-772; Jedicke, R., Nesvorný, D., Whiteley, R.J., Ivezić, Ž., Jurić, M. [2004]. Nature 429, 275-277; Willman, M., Jedicke, R., Nesvorny, D., Moskovitz, N., Ivezić, Ž., Fevig, R. [2008]. Icarus 195, 663-673. We used a sample of 95 S-complex asteroids from SMASS and obtained their absolute magnitudes and u, g, r, i, z filter magnitudes from SDSS. The absolute magnitudes yield a size-derived age distribution. The u, g, r, i, z filter magnitudes lead to the principal component color which yields a color-derived age distribution by inverting our color-age relationship, an enhanced version of the 'dual τ' space weathering model of Willman et al. (2010). We fit the size-age distribution to the enhanced dual τ model and found characteristic weathering and gardening times of τw = 2050 ± 80 Myr and τg=4400-500+700Myr respectively. The fit also suggests an initial principal component color of -0.05 ± 0.01 for fresh asteroid surface with a maximum possible change of the probable color due to weathering of Δ PC = 1.34 ± 0.04. Our predicted color of fresh asteroid surface matches the color of fresh ordinary chondritic surface of PC1 = 0.17 ± 0.39.

  18. Deposition times in the northeastern United States during the Holocene: establishing valid priors for Bayesian age models

    NASA Astrophysics Data System (ADS)

    Goring, S.; Williams, J. W.; Blois, J. L.; Jackson, S. T.; Paciorek, C. J.; Booth, R. K.; Marlon, J. R.; Blaauw, M.; Christen, J. A.

    2012-08-01

    Bayesian approaches since there is strong variation in the gamma parameters both in the most recent sediments and throughout the Holocene. Time-averaged gamma distributions for lacustrine (α = 1.35, β = 19.64) and palustrine samples (α = 1.40, β = 20.72) show lower overall deposition times, but variability remains. The variation in gamma parameters through time may require the use of multiple gamma distributions during the Holocene to generate accurate age-depth models. We present estimates of gamma parameters for deposition times at 1000 yr intervals. The parameters generated in this study can be used directly within Bacon to act as Bayesian priors for sedimentary age models.

  19. GDF11 administration does not extend lifespan in a mouse model of premature aging

    PubMed Central

    Freitas-Rodríguez, Sandra; Rodríguez, Francisco; Folgueras, Alicia R.

    2016-01-01

    GDF11 has recently emerged as a powerful anti-aging candidate, found in young blood, capable of rejuvenating a number of aged tissues, such as heart, skeletal muscle and brain. However, recent reports have shown contradictory data questioning its capacity to reverse age-related tissue dysfunction. The availability of a mouse model of accelerated aging, which shares most of the features occurring in physiological aging, gives us an excellent opportunity to test in vivo therapies aimed at extending lifespan both in pathological and normal aging. On this basis, we wondered whether the proposed anti-aging functions of GDF11 would have an overall effect on longevity. We first confirmed the existence of a reduction in GDF11/8 levels in our mouse model of accelerated aging compared with wild-type littermates. However, we show herein that GDF11 daily administration does not extend lifespan of premature-aged mice. PMID:27507054

  20. The ageing lens and cataract: a model of normal and pathological ageing.

    PubMed

    Michael, R; Bron, A J

    2011-04-27

    Cataract is a visible opacity in the lens substance, which, when located on the visual axis, leads to visual loss. Age-related cataract is a cause of blindness on a global scale involving genetic and environmental influences. With ageing, lens proteins undergo non-enzymatic, post-translational modification and the accumulation of fluorescent chromophores, increasing susceptibility to oxidation and cross-linking and increased light-scatter. Because the human lens grows throughout life, the lens core is exposed for a longer period to such influences and the risk of oxidative damage increases in the fourth decade when a barrier to the transport of glutathione forms around the lens nucleus. Consequently, as the lens ages, its transparency falls and the nucleus becomes more rigid, resisting the change in shape necessary for accommodation. This is the basis of presbyopia. In some individuals, the steady accumulation of chromophores and complex, insoluble crystallin aggregates in the lens nucleus leads to the formation of a brown nuclear cataract. The process is homogeneous and the affected lens fibres retain their gross morphology. Cortical opacities are due to changes in membrane permeability and enzyme function and shear-stress damage to lens fibres with continued accommodative effort. Unlike nuclear cataract, progression is intermittent, stepwise and non-uniform.

  1. Testing Models of Psychopathology in Preschool-aged Children Using a Structured Interview-based Assessment

    PubMed Central

    Dougherty, Lea R.; Bufferd, Sara J.; Carlson, Gabrielle A.; Klein, Daniel N.

    2014-01-01

    A number of studies have found that broadband internalizing and externalizing factors provide a parsimonious framework for understanding the structure of psychopathology across childhood, adolescence, and adulthood. However, few of these studies have examined psychopathology in young children, and several recent studies have found support for alternative models, including a bi-factor model with common and specific factors. The present study used parents’ (typically mothers’) reports on a diagnostic interview in a community sample of 3-year old children (n=541; 53.9 % male) to compare the internalizing-externalizing latent factor model with a bi-factor model. The bi-factor model provided a better fit to the data. To test the concurrent validity of this solution, we examined associations between this model and paternal reports and laboratory observations of child temperament. The internalizing factor was associated with low levels of surgency and high levels of fear; the externalizing factor was associated with high levels of surgency and disinhibition and low levels of effortful control; and the common factor was associated with high levels of surgency and negative affect and low levels of effortful control. These results suggest that psychopathology in preschool-aged children may be explained by a single, common factor influencing nearly all disorders and unique internalizing and externalizing factors. These findings indicate that shared variance across internalizing and externalizing domains is substantial and are consistent with recent suggestions that emotion regulation difficulties may be a common vulnerability for a wide array of psychopathology. PMID:24652485

  2. Testing models of psychopathology in preschool-aged children using a structured interview-based assessment.

    PubMed

    Olino, Thomas M; Dougherty, Lea R; Bufferd, Sara J; Carlson, Gabrielle A; Klein, Daniel N

    2014-10-01

    A number of studies have found that broadband internalizing and externalizing factors provide a parsimonious framework for understanding the structure of psychopathology across childhood, adolescence, and adulthood. However, few of these studies have examined psychopathology in young children, and several recent studies have found support for alternative models, including a bi-factor model with common and specific factors. The present study used parents' (typically mothers') reports on a diagnostic interview in a community sample of 3-year old children (n = 541; 53.9 % male) to compare the internalizing-externalizing latent factor model with a bi-factor model. The bi-factor model provided a better fit to the data. To test the concurrent validity of this solution, we examined associations between this model and paternal reports and laboratory observations of child temperament. The internalizing factor was associated with low levels of surgency and high levels of fear; the externalizing factor was associated with high levels of surgency and disinhibition and low levels of effortful control; and the common factor was associated with high levels of surgency and negative affect and low levels of effortful control. These results suggest that psychopathology in preschool-aged children may be explained by a single, common factor influencing nearly all disorders and unique internalizing and externalizing factors. These findings indicate that shared variance across internalizing and externalizing domains is substantial and are consistent with recent suggestions that emotion regulation difficulties may be a common vulnerability for a wide array of psychopathology.

  3. Using Set Covering with Item Sampling to Analyze the Infeasibility of Linear Programming Test Assembly Models

    ERIC Educational Resources Information Center

    Huitzing, Hiddo A.

    2004-01-01

    This article shows how set covering with item sampling (SCIS) methods can be used in the analysis and preanalysis of linear programming models for test assembly (LPTA). LPTA models can construct tests, fulfilling a set of constraints set by the test assembler. Sometimes, no solution to the LPTA model exists. The model is then said to be…

  4. Analysis of the machinery and intermediates of the 5hmC-mediated DNA demethylation pathway in aging on samples from the MARK-AGE Study.

    PubMed

    Valentini, Elisabetta; Zampieri, Michele; Malavolta, Marco; Bacalini, Maria Giulia; Calabrese, Roberta; Guastafierro, Tiziana; Reale, Anna; Franceschi, Claudio; Hervonen, Antti; Koller, Bernhard; Bernhardt, Jürgen; Slagboom, P Eline; Toussaint, Olivier; Sikora, Ewa; Gonos, Efstathios S; Breusing, Nicolle; Grune, Tilman; Jansen, Eugène; Dollé, Martijn E T; Moreno-Villanueva, María; Sindlinger, Thilo; Bürkle, Alexander; Ciccarone, Fabio; Caiafa, Paola

    2016-08-29

    Gradual changes in the DNA methylation landscape occur throughout aging virtually in all human tissues. A widespread reduction of 5-methylcytosine (5mC), associated with highly reproducible site-specific hypermethylation, characterizes the genome in aging. Therefore, an equilibrium seems to exist between general and directional deregulating events concerning DNA methylation controllers, which may underpin the age-related epigenetic changes. In this context, 5mC-hydroxylases (TET enzymes) are new potential players. In fact, TETs catalyze the stepwise oxidation of 5mC to 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC) and 5-carboxylcytosine (5caC), driving the DNA demethylation process based on thymine DNA glycosylase (TDG)-mediated DNA repair pathway. The present paper reports the expression of DNA hydroxymethylation components, the levels of 5hmC and of its derivatives in peripheral blood mononuclear cells of age-stratified donors recruited in several European countries in the context of the EU Project 'MARK-AGE'. The results provide evidence for an age-related decline of TET1, TET3 and TDG gene expression along with a decrease of 5hmC and an accumulation of 5caC. These associations were independent of confounding variables, including recruitment center, gender and leukocyte composition. The observed impairment of 5hmC-mediated DNA demethylation pathway in blood cells may lead to aberrant transcriptional programs in the elderly.

  5. Autophagy drives epidermal deterioration in a Drosophila model of tissue aging.

    PubMed

    Scherfer, Christoph; Han, Violet C; Wang, Yan; Anderson, Aimee E; Galko, Michael J

    2013-04-01

    Organismal lifespan has been the primary readout in aging research. However, how longevity genes control tissue-specific aging remains an open question. To examine the crosstalk between longevity programs and specific tissues during aging, biomarkers of organ-specific aging are urgently needed. Since the earliest signs of aging occur in the skin, we sought to examine skin aging in a genetically tractable model. Here we introduce a Drosophila model of skin aging. The epidermis undergoes a dramatic morphological deterioration with age that includes membrane and nuclear loss. These changes were decelerated in a long-lived mutant and accelerated in a short-lived mutant. An increase in autophagy markers correlated with epidermal aging. Finally, the epidermis of Atg7 mutants retained younger characteristics, suggesting that autophagy is a critical driver of epidermal aging. This is surprising given that autophagy is generally viewed as protective during aging. Since Atg7 mutants are short-lived, the deceleration of epidermal aging in this mutant suggests that in the epidermis healthspan can be uncoupled from longevity. Because the aging readout we introduce here has an early onset and is easily visualized, genetic dissection using our model should identify other novel mechanisms by which lifespan genes feed into tissue-specific aging.

  6. Optimizing a Male Reproductive Aging Mouse Model by d-Galactose Injection

    PubMed Central

    Liao, Chun-Hou; Chen, Bing-Huei; Chiang, Han-Sun; Chen, Chiu-Wei; Chen, Mei-Feng; Ke, Chih-Chun; Wang, Ya-Yun; Lin, Wei-Ning; Wang, Chi-Chung; Lin, Ying-Hung

    2016-01-01

    The d-galactose (d-gal)-injected animal model, which is typically established by administering consecutive subcutaneous d-gal injections to animals for approximately six or eight weeks, has been frequently used for aging research. In addition, this animal model has been demonstrated to accelerate aging in the brain, kidneys, liver and blood cells. However, studies on aging in male reproductive organs that have used this animal model remain few. Therefore, the current study aimed to optimize a model of male reproductive aging by administering d-gal injections to male mice and to determine the possible mechanism expediting senescence processes during spermatogenesis. In this study, C57Bl/6 mice were randomized into five groups (each containing 8–10 mice according to the daily intraperitoneal injection of vehicle control or 100 or 200 mg/kg dosages of d-gal for a period of six or eight weeks). First, mice subjected to d-gal injections for six or eight weeks demonstrated considerably decreased superoxide dismutase activity in the serum and testis lysates compared to those in the control group. The lipid peroxidation in testis also increased in the d-gal-injected groups. Furthermore, the d-gal-injected groups exhibited a decreased ratio of testis weight/body weight and sperm count compared to the control group. The percentages of both immotile sperm and abnormal sperm increased considerably in the d-gal-injected groups compared to those of the control group. To determine the genes influenced by the d-gal injection during murine spermatogenesis, a c-DNA microarray was conducted to compare testicular RNA samples between the treated groups and the control group. The d-gal-injected groups exhibited RNA transcripts of nine spermatogenesis-related genes (Cycl2, Hk1, Pltp, Utp3, Cabyr, Zpbp2, Speer2, Csnka2ip and Katnb1) that were up- or down-regulated by at least two-fold compared to the control group. Several of these genes are critical for forming sperm-head morphologies

  7. New Ages for Gorgona Island, Colombia: Implications for Previous Petrogenetic and Tectonic Models

    NASA Astrophysics Data System (ADS)

    Serrano Duran, L.; Lopez Martinez, M.; Ferrari, L.

    2007-05-01

    reliable plateau and/or isochron ages. Only one basaltic sample, located in the western coast, yielded an age comparable with those previously reported in the literature. For two basalts intercalated with komatiites and a gabbro exposed in the north-eastern coast of the island we obtained younger ages, similar to those reported for some mafic and ultramafic rocks along the Pacific coast of Colombia. The two sets of ages for the ultramafic suite of Gorgona also correspond to different petrologic types. The depleted rocks in the eastern coast are younger than the enriched basalts and picrites located in the southern and western part of the island with ages around 90 Ma, suggesting a more complex tectonic evolution with the accretion of at least two different blocks. This eventually questions the "single plume" model for the formation of the Gorgona Island plateau.

  8. Thermal characterization and model free kinetics of aged epoxies and foams using TGA and DSC methods.

    SciTech Connect

    Cordaro, Joseph Gabriel; Kruizenga, Alan Michael; Nissen, April

    2013-10-01

    Two classes of materials, poly(methylene diphenyl diisocyanate) or PMDI foam, and cross-linked epoxy resins, were characterized using thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC), to help understand the effects of aging and %E2%80%9Cbake-out%E2%80%9D. The materials were evaluated for mass loss and the onset of decomposition. In some experiments, volatile materials released during heating were analyzed via mass spectroscopy. In all, over twenty materials were evaluated to compare the mass loss and onset temperature for decomposition. Model free kinetic (MFK) measurements, acquired using variable heating rate TGA experiments, were used to calculate the apparent activation energy of thermal decomposition. From these compiled data the effects of aging, bake-out, and sample history on the thermal stability of materials were compared. No significant differences between aged and unaged materials were detected. Bake-out did slightly affect the onset temperature of decomposition but only at the highest bake-out temperatures. Finally, some recommendations for future handling are made.

  9. Development of the Japanese reference man model for age-specific phantoms.

    PubMed

    Kawamura, Hisao

    2012-03-01

    Recent interest in improving methods for calculating radiation doses to atomic bomb survivors necessitates reinforcing the data on masses of organs of the Japanese population in 1945, including those that are not calculated by DS02, as well as increasing the number of phantoms for different ages. Reference is made to published data on the masses of organs in normal Japanese subjects of 0-90 y of age with more than 5000 samples during 1970-80, as well as the weight and size of the total body. The first Japanese Reference Man model, primarily based on these data and following the ICRP Reference Man concept, is briefly explained. It provides a set of reference values for males and females of six age groups, i.e. 3 months, 1, 5, 10, 15 and 20-50 y. To consider the organ masses of the Japanese population in 1945, the data during the period 1970-80 are compared with the literature data of normal Japanese reported in 1952. Differences between the two sets of organ data in adults are discussed in relation to changes in the national status of nutrition. Additional organ masses of current interest for the Japanese population in 1945 are preliminarily considered.

  10. Age-Related Differences in Sleep Architecture and Electroencephalogram in Adolescents in the National Consortium on Alcohol and Neurodevelopment in Adolescence Sample

    PubMed Central

    Baker, Fiona C.; Willoughby, Adrian R.; de Zambotti, Massimiliano; Franzen, Peter L.; Prouty, Devin; Javitz, Harold; Hasler, Brant; Clark, Duncan B.; Colrain, Ian M.

    2016-01-01

    Study Objectives: To investigate age-related differences in polysomnographic and sleep electroencephalographic (EEG) measures, considering sex, pubertal stage, ethnicity, and scalp topography in a large group of adolescents in the National Consortium on Alcohol and NeuroDevelopment in Adolescence (NCANDA). Methods: Following an adaptation/clinical screening night, 141 healthy adolescents (12–21 y, 64 girls) had polysomnographic recordings, from which sleep staging and EEG measures were derived. The setting was the SRI International Human Sleep Laboratory and University of Pittsburgh Pediatric Sleep Laboratory. Results: Older age was associated with a lower percentage of N3 sleep, accompanied by higher percentages of N2, N1, and rapid eye movement (REM) sleep. Older boys compared with younger boys had more frequent awakenings and wakefulness after sleep onset, effects that were absent in girls. Delta (0.3–4 Hz) EEG power in nonrapid eye movement NREM sleep was lower in older than younger adolescents at all electrode sites, with steeper slopes of decline over the occipital scalp. EEG power in higher frequency bands was also lower in older adolescents than younger adolescents, with equal effects across electrodes. Percent delta power in the first NREM period was similar across age. African Americans had lower EEG power across frequency bands (delta to sigma) compared with Caucasians. Finally, replacing age with pubertal status in the models showed similar relationships. Conclusions: Substantial differences in sleep architecture and EEG were evident across adolescence in this large group, with sex modifying some relationships. Establishment and follow-up of this cohort allows the investigation of sleep EEG-brain structural relationships and the effect of behaviors, such as alcohol and substance use, on sleep EEG maturation. Citation: Baker FC, Willoughby AR, de Zambotti M, Franzen PL, Prouty D, Javitz H, Hasler B, Clark DB, Colrain IM. Age-related differences in

  11. Late Quaternary sedimentological and climate changes at Lake Bosumtwi Ghana: new constraints from laminae analysis and radiocarbon age modeling

    USGS Publications Warehouse

    Shanahan, Timothy M.; Beck, J. Warren; Overpeck, Jonathan T.; McKay, Nicholas P.; Pigati, Jeffrey S.; Peck, John A.; Scholz, Christopher A.; Heil, Clifford W.; King, John W.

    2012-01-01

    The Lake Bosumtwi sediment record represents one of the longest and highest-resolution terrestrial records of paleoclimate change available from sub-Saharan Africa. Here we report a new sediment age model framework for the last ~ 45 cal kyr of sedimentation using a combination of high-resolution radiocarbon dating, Bayesian age-depth modeling and lamination counting. Our results highlight the practical limits of these methods for reducing age model uncertainties and suggest that even with very high sampling densities, radiocarbon uncertainties of at least a few hundred years are unavoidable. Age model uncertainties are smallest during the Holocene (205 yr) and the glacial (360 yr) but are large at the base of the record (1660 yr), due to a combination of decreasing sample density, larger calibration uncertainties and increases in radiocarbon age scatter. For portions of the chronology older than ~ 35 cal kyr, additional considerations, such as the use of a low-blank graphitization system and more rigorous sample pretreatment were necessary to generate a reliable age depth model because of the incorporation of small amounts of younger carbon. A comparison of radiocarbon age model results and lamination counts over the time interval ~ 15–30 cal kyr agree with an overall discrepancy of ~ 10% and display similar changes in sedimentation rate, supporting the annual nature of sediment laminations in the early part of the record. Changes in sedimentation rates reconstructed from the age-depth model indicate that intervals of enhanced sediment delivery occurred at 16–19, 24 and 29–31 cal kyr, broadly synchronous with reconstructed drought episodes elsewhere in northern West Africa and potentially, with changes in Atlantic meridional heat transport during North Atlantic Heinrich events. These data suggest that millennial-scale drought events in the West African monsoon region were latitudinally extensive, reaching within several hundred kilometers of the Guinea coast

  12. Abnormal glutamate release in aged BTBR mouse model of autism.

    PubMed

    Wei, Hongen; Ding, Caiyun; Jin, Guorong; Yin, Haizhen; Liu, Jianrong; Hu, Fengyun

    2015-01-01

    Autism is a neurodevelopmental disorder characterized by abnormal reciprocal social interactions, communication deficits, and repetitive behaviors with restricted interests. Most of the available research on autism is focused on children and young adults and little is known about the pathological alternation of autism in older adults. In order to investigate the neurobiological alternation of autism in old age stage, we compared the morphology and synaptic function of excitatory synapses between the BTBR mice with low level sociability and B6 mice with high level sociability. The results revealed that the number of excitatory synapse colocalized with pre- and post-synaptic marker was not different between aged BTBR and B6 mice. The aged BTBR mice had a normal structure of dendritic spine and the expression of Shank3 protein in the brain as well as that in B6 mice. The baseline and KCl-evoked glutamate release from the cortical synaptoneurosome in aged BTBR mice was lower than that in aged B6 mice. Overall, the data indicate that there is a link between disturbances of the glutamate transmission and autism. These findings provide new evidences for the hypothesis of excitation/inhibition imbalance in autism. Further work is required to determine the cause of this putative abnormality.

  13. New models for age estimation and assessment of their accuracy using developing mandibular third molar teeth in a Thai population.

    PubMed

    Duangto, P; Iamaroon, A; Prasitwattanaseree, S; Mahakkanukrauh, P; Janhom, A

    2017-03-01

    Age estimation using developing third molar teeth is considered an important and accurate technique for both clinical and forensic practices. The aims of this study were to establish population-specific reference data, to develop age prediction models using mandibular third molar development, to test the accuracy of the resulting models, and to find the probability of persons being at the age thresholds of legal relevance in a Thai population. A total of 1867 digital panoramic radiographs of Thai individuals aged between 8 and 23 years was selected to assess dental age. The mandibular third molar development was divided into nine stages. The stages were evaluated and each stage was transformed into a development score. Quadratic regression was employed to develop age prediction models. Our results show that males reached mandibular third molar root formation stages earlier than females. The models revealed a high correlation coefficient for both left and right mandibular third molar teeth in both sexes (R = 0.945 and 0.944 in males, R = 0.922 and 0.923 in females, respectively). Furthermore, the accuracy of the resulting models was tested in randomly selected 374 cases and showed low error values between the predicted dental age and the chronological age for both left and right mandibular third molar teeth in both sexes (-0.13 and -0.17 years in males, 0.01 and 0.03 years in females, respectively). In Thai samples, when the mandibular third molar teeth reached stage H, the probability of the person being over 18 years was 100 % in both sexes.

  14. Estimating species – area relationships by modeling abundance and frequency subject to incomplete sampling

    USGS Publications Warehouse

    Yamaura, Yuichi; Connor, Edward F.; Royle, Andy; Itoh, Katsuo; Sato, Kiyoshi; Taki, Hisatomo; Mishima, Yoshio

    2016-01-01

    Models and data used to describe species–area relationships confound sampling with ecological process as they fail to acknowledge that estimates of species richness arise due to sampling. This compromises our ability to make ecological inferences from and about species–area relationships. We develop and illustrate hierarchical community models of abundance and frequency to estimate species richness. The models we propose separate sampling from ecological processes by explicitly accounting for the fact that sampled patches are seldom completely covered by sampling plots and that individuals present in the sampling plots are imperfectly detected. We propose a multispecies abundance model in which community assembly is treated as the summation of an ensemble of species-level Poisson processes and estimate patch-level species richness as a derived parameter. We use sampling process models appropriate for specific survey methods. We propose a multispecies frequency model that treats the number of plots in which a species occurs as a binomial process. We illustrate these models using data collected in surveys of early-successional bird species and plants in young forest plantation patches. Results indicate that only mature forest plant species deviated from the constant density hypothesis, but the null model suggested that the deviations were too small to alter the form of species–area relationships. Nevertheless, results from simulations clearly show that the aggregate pattern of individual species density–area relationships and occurrence probability–area relationships can alter the form of species–area relationships. The plant community model estimated that only half of the species present in the regional species pool were encountered during the survey. The modeling framework we propose explicitly accounts for sampling processes so that ecological processes can be examined free of sampling artefacts. Our modeling approach is extensible and could be applied

  15. Negative emotionality, depressive symptoms and cortisol diurnal rhythms: analysis of a community sample of middle-aged males.

    PubMed

    Doane, Leah D; Franz, Carol E; Prom-Wormley, Elizabeth; Eaves, Lindon J; Mendoza, Sally P; Hellhammer, Dirk H; Lupien, Sonia; Xian, Hong; Lyons, Michael J; Kremen, William; Jacobson, Kristen C

    2011-07-01

    Prior research suggests that individuals with particular personality traits, like negative emotionality, are at greater risk for adverse health outcomes. Despite bivariate associations between negative emotionality, depressive symptoms and the hypothalamic pituitary adrenal axis (HPA axis), few studies have sought to understand the biological pathways through which negative emotionality, depressive symptomatology and cortisol-one of the primary hormonal products of the HPA axis--are associated. The present study explored whether negative emotionality influenced cortisol dysregulation through current depressive symptomatology and whether negative emotionality served as a moderator of the relationship between depressive symptoms and cortisol. In the community-based Vietnam Era Twin Study of Aging, 783 male twins completed two days of cortisol saliva sampling in their natural environments. Three measures of cortisol were analyzed: waking levels, the cortisol awakening response, and the peak to bed slope. Depressive symptoms significantly mediated the associations between negative emotionality and the peak to bed slope. A 2-way interaction between depressive symptoms and negative emotionality was significant for the peak to bed slope and for waking levels of cortisol. Exploration of the interactions illustrated that depressive symptoms only affected cortisol slopes at average or high levels of negative emotionality and only affected waking levels at low levels of negative emotionality. Negative emotionality and depressive symptoms were not related to the cortisol awakening response. This is the first study to find indirect associations between negative emotionality and peak to bed cortisol slopes through depressive symptoms. These findings illustrate the complex interplay between personality characteristics, depressive symptoms and different indices of the cortisol diurnal rhythm.

  16. Influenza and pneumococcal vaccine coverage among a random sample of hospitalised persons aged 65 years or more, Victoria.

    PubMed

    Andrews, Ross M; Skull, Susan A; Byrnes, Graham B; Campbell, Donald A; Turner, Joy L; McIntyre, Peter B; Kelly, Heath A

    2005-01-01

    This study was undertaken to assess the uptake of influenza and pneumococcal vaccination based on provider records of the hospitalised elderly, a group at high risk of influenza and pneumococcal disease. The study used a random sample of 3,204 admissions at two Victorian teaching hospitals for patients, aged 65 years or more who were discharged between 1 April 2000 and 31 March 2002. Information on whether the patient had received an influenza vaccination within the year prior to admission or pneumococcal vaccination within the previous five years was ascertained from the patient's nominated medical practitioner/vaccine provider. Vaccination records were obtained from providers for 82 per cent (2,804/2,934) of eligible subjects. Influenza vaccine coverage was 70.9 per cent (95% CI 68.9-72.9), pneumococcal coverage was 52.6 per cent (95% CI 50.4-54.8) and 46.6 per cent (95% CI 44.4-48.8) had received both vaccines. Coverage for each vaccine increased seven per cent over the two study years. For pneumococcal vaccination, there was a marked increase in 1998 coinciding with the introduction of Victoria's publicly funded program. Influenza and pneumococcal vaccine coverage in eligible hospitalised adults was similar to, but did not exceed, estimates in the general elderly population. Pneumococcal vaccination coverage reflected the availability of vaccine through Victoria's publicly funded program. A nationally funded pneumococcal vaccination program for the elderly, as announced recently, should improve coverage. However, these data highlight the need for greater awareness of pneumococcal vaccine among practitioners and for systematic recording of vaccination status, as many of these subjects will soon become eligible for revaccination.

  17. Negative Emotionality, Depressive Symptoms and Cortisol Diurnal Rhythms: Analysis of a Community Sample of Middle-Aged Males

    PubMed Central

    Doane, Leah D.; Franz, Carol E.; Prom-Wormley, Elizabeth; Eaves, Lindon J.; Mendoza, Sally P.; Hellhammer, Dirk H.; Lupien, Sonia; Xian, Hong; Lyons, Michael J.; Kremen, William; Jacobson, Kristen C.

    2011-01-01

    Prior research suggests that individuals with particular personality traits, like negative emotionality, are at greater risk for adverse health outcomes. Despite bivariate associations between negative emotionality, depressive symptoms and the hypothalamic pituitary adrenal axis (HPA axis), few studies have sought to understand the biological pathways through which negative emotionality, depressive symptomology and cortisol--one of the primary hormonal products of the HPA axis--are associated. The present study explored whether negative emotionality influenced cortisol dysregulation through current depressive symptomatology and whether negative emotionality served as a moderator of the relationship between depressive symptoms and cortisol. In the community-based Vietnam Era Twin Study of Aging, 783 male twins completed two days of cortisol saliva sampling in their natural environments. Three measures of cortisol were analyzed: waking levels, the cortisol awakening response, and the peak to bed slope. Depressive symptoms significantly mediated the associations between negative emotionality and the peak to bed slope. A 2-way interaction between depressive symptoms and negative emotionality was significant for the peak to bed slope and for waking levels of cortisol. Exploration of the interactions illustrated that depressive symptoms only affected cortisol slopes at average or high levels of negative emotionality and only affected waking levels at low levels of negative emotionality. Negative emotionality and depressive symptoms were not related to the cortisol awakening response. This is the first study to find indirect associations between negative emotionality and peak to bed cortisol slopes through depressive symptoms. These findings illustrate the complex interplay between personality characteristics, depressive symptoms and different indices of the cortisol diurnal rhythm. PMID:21619882

  18. NMR and molecular modeling: application to wine ageing

    NASA Astrophysics Data System (ADS)

    Saucier, C.; Pianet, I.; Laguerre, M.; Glories, Y.

    1998-02-01

    Red wine contains polyphenols called tannins which are very important for its taste and longevity. These polymers consist in repeating units of catechin and its epimer epicatechin. During ageing, slow condensation reactions take place which lead to new chemical structures. Among the possible reactions, we have focused our attention on acetaldehyde cross-linking. Catechin was used as a model for the production of polymers with acetaldehyde. Two reaction product fractions have been isolated by liquid chromatography. Mass measurement indicated that these fractions contain dimers. NMR (1D and 2D) and molecular modelling were then used to study the structure and conformations of these products. The first product consist in a pure dimer with the two catechin moieties connected with an ethyl bridge on the carbon 6 and 8. The second fraction was a mixture of two dimers (50/50). NMR measurements showed that it could be two symmetrical dimers involving the same carbon for each catechin moiety (6 or8). Le vin rouge contient des polyphénols appelés tanins qui sont très importants pour son goût et sa longévité. Il s'agit principalement de polymères de catéchine et d'épicatéchine. Durant le vieillissement du vin, des réactions de condensation interviennent lentement et conduisent à de nouvelles structures. Parmi les réactions possibles, nous avons plus spécialement étudié la polymérisation par pontage avec l'éthanal. La catéchine a été utilisée comme modèle de tannin et mise en présence d'éthanal en milieu acide proche du vin. Deux fractions de produits de réaction ont été isolées par chromatographie liquide. La spectrométrie de masse a révélé la présence de dimères. La RMN (1D et 2D) et la modélisation moléculaire ont ensuite été utilisées pour déterminer la structure et la conformation de ces produits. La première fraction a été identifiée comme étant un dimère de deux unités catéchines reliées par un pont éthyle par leur

  19. Analysis of the machinery and intermediates of the 5hmC-mediated DNA demethylation pathway in aging on samples from the MARK-AGE Study

    PubMed Central

    Valentini, Elisabetta; Zampieri, Michele; Malavolta, Marco; Bacalini, Maria Giulia; Calabrese, Roberta; Guastafierro, Tiziana; Reale, Anna; Franceschi, Claudio; Hervonen, Antti; Koller, Bernhard; Bernhardt, Jürgen; Slagboom, P. Eline; Toussaint, Olivier; Sikora, Ewa; Gonos, Efstathios S.; Breusing, Nicolle; Grune, Tilman; Jansen, Eugène; Dollé, Martijn E.T.; Moreno-Villanueva, María; Sindlinger, Thilo; Bürkle, Alexander; Ciccarone, Fabio; Caiafa, Paola

    2016-01-01

    Gradual changes in the DNA methylation landscape occur throughout aging virtually in all human tissues. A widespread reduction of 5-methylcytosine (5mC), associated with highly reproducible site-specific hypermethylation, characterizes the genome in aging. Therefore, an equilibrium seems to exist between general and directional deregulating events concerning DNA methylation controllers, which may underpin the age-related epigenetic changes. In this context, 5mC-hydroxylases (TET enzymes) are new potential players. In fact, TETs catalyze the stepwise oxidation of 5mC to 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC) and 5-carboxylcytosine (5caC), driving the DNA demethylation process based on thymine DNA glycosylase (TDG)-mediated DNA repair pathway. The present paper reports the expression of DNA hydroxymethylation components, the levels of 5hmC and of its derivatives in peripheral blood mononuclear cells of age-stratified donors recruited in several European countries in the context of the EU Project ‘MARK-AGE’. The results provide evidence for an age-related decline of TET1, TET3 and TDG gene expression along with a decrease of 5hmC and an accumulation of 5caC. These associations were independent of confounding variables, including recruitment center, gender and leukocyte composition. The observed impairment of 5hmC-mediated DNA demethylation pathway in blood cells may lead to aberrant transcriptional programs in the elderly. PMID:27587280

  20. Evaluation of status of trace and toxic metals in biological samples (scalp hair, blood, and urine) of normal and anemic children of two age groups.

    PubMed

    Shah, Faheem; Kazi, Tasneem Gul; Afridi, Hassan Imran; Kazi, Naveed; Baig, Jameel Ahmed; Shah, Abdul Qadir; Khan, Sumaira; Kolachi, Nida Fatima; Wadhwa, Sham Kumar

    2011-06-01

    Anemia affects a substantial portion of the world's population, provoking severe health problems as well as important economic losses to the region in which this condition is found. This study was designed to compare the levels of essential trace and toxic elements in scalp hair, blood, and urine samples of anemic children (n = 132) with age range 1-5 and 6-10 years of both genders. For a comparative study, 134 non-anemic age- and sex-matched children as control subjects, residing in the same city, were selected. The metals in the biological samples were measured by flame atomic absorption spectrophotometry/electrothermal atomic absorption spectrometry prior to microwave-assisted acid digestion. The proposed method was validated using certified reference samples of hair, blood, and urine. The results indicated significantly lower levels of iron, copper, and zinc in the biological samples as compared to the control children of both genders (p = 0.01-0.008). The mean values of lead and cadmium were significantly high in all three biological samples of anemic children as compared to non-anemic children of both age groups (p = 0.005-0.001). The ratios of essential metal to toxic metals in the biological samples of anemic children of both age groups were significantly lower than that of controls. Deficiency of essential trace metals and high level of toxic metals may play a role in the development of anemia in the subjects under study.

  1. Estimating Age-Specific Immunity and Force of Infection of Varicella Zoster Virus in Norway Using Mixture Models

    PubMed Central

    Rimseliene, Grazina; Flem, Elmira; Freiesleben de Blasio, Birgitte; Scalia Tomba, Gianpaolo; Manfredi, Piero

    2016-01-01

    This study applies mixture modelling to examine age-specific immunity to varicella zoster virus (VZV) infection in Norway based on the first large-scale serological study in the general population. We estimated the seropositive proportions at different ages and calculated the underlying force of infection by using a sample of 2103 residual sera obtained from patients seeking primary and hospital care. A rapid increase in the VZV-associated immunity is observed in the first years of life with 63% of children being immune by age 5. The increase in the immunity levels slows down thereafter, with a large proportion of adults still susceptible by age 20 (around 14.5%), thus at risk of serious sequelae of varicella infection. The corresponding force of infection peaks during the preschool period, subsequently declines to a minimum between ages 10 and 20 years, and afterwards moderately increases to reach a plateau lasting throughout the childbearing period. In comparison with the traditional cut-off approach, mixture modelling used the whole data without producing any inconclusive cases, led to an unbiased classification of individuals between susceptible and immune, and provided a smoother immune profile by age. These findings represent an important step towards any decision about the introduction of varicella vaccination in Norway, as they are a primary input for mathematical transmission models aimed at evaluating potential vaccination scenarios. PMID:27689800

  2. Construction of mass-age curves for the continental crust: An empirical model and an example from the western US

    NASA Technical Reports Server (NTRS)

    Depaolo, D. J.; Schubert, G. S.; Linn, Ann

    1988-01-01

    The methodology of determining crustal mass-age curves is discussed. Problems in doing this include determination of model ages and accounting for mixing of materials of different ages during crust forming processes. These difficulties can be overcome with some reasonable assumptions and estimates of rock volumes based on areal proportions. This technique was used to construct a reasonably well constrained mass-age curve for the southwestern U.S. based on isotopic measurements on over 100 samples. The results imply that the crust in this area grew episodically at 2.8, 1.8, and 0.1 Ga. It is estimated that it would take on the order of 10000 to 100000 individual Sm-Nd isotopic measurements to carry out a similar exercise for continental crust world wide.

  3. [Outlier sample discriminating methods for building calibration model in melons quality detecting using NIR spectra].

    PubMed

    Tian, Hai-Qing; Wang, Chun-Guang; Zhang, Hai-Jun; Yu, Zhi-Hong; Li, Jian-Kang

    2012-11-01

    Outlier samples strongly influence the precision of the calibration model in soluble solids content measurement of melons using NIR Spectra. According to the possible sources of outlier samples, three methods (predicted concentration residual test; Chauvenet test; leverage and studentized residual test) were used to discriminate these outliers respectively. Nine suspicious outliers were detected from calibration set which including 85 fruit samples. Considering the 9 suspicious outlier samples maybe contain some no-outlier samples, they were reclaimed to the model one by one to see whether they influence the model and prediction precision or not. In this way, 5 samples which were helpful to the model joined in calibration set again, and a new model was developed with the correlation coefficient (r) 0. 889 and root mean square errors for calibration (RMSEC) 0.6010 Brix. For 35 unknown samples, the root mean square errors prediction (RMSEP) was 0.854 degrees Brix. The performance of this model was more better than that developed with non outlier was eliminated from calibration set (r = 0.797, RMSEC= 0.849 degrees Brix, RMSEP = 1.19 degrees Brix), and more representative and stable with all 9 samples were eliminated from calibration set (r = 0.892, RMSEC = 0.605 degrees Brix, RMSEP = 0.862 degrees).

  4. Identification of aged bloodstains through mRNA profiling: Experiments results on selected markers of 30- and 50-year-old samples.

    PubMed

    Zhao, Hemiao; Wang, Chong; Yao, Lan; Lin, Qingluan; Xu, XiuLan; Hu, Lan; Li, Wanshui

    2017-03-01

    Remarkable progress has been made in recent years on the research of body fluid identification through messenger RNA(mRNA) profiling. In order to examine the viability of mRNA profiling as a method to identify aged bloodstains, this study tested two groups of bloodstain samples, dated 30 years and 50 years back respectively, on seven blood specific markers, i.e. HBB, HBA, GYPA, CD93, ALAS2, SPTB (91bp and 247bp primers), and PBGD. Test results indicate that HBA and HBB are the most stable markers in aged bloodstains, returning positive results in over 80% of the 50-year-old samples and over 90% of the 30-year-old samples. This finding proves mRNA profiling an effective way of identifying aged bloodstains.

  5. Aging and Predicting Inferences: A Diffusion Model Analysis

    ERIC Educational Resources Information Center

    McKoon, Gail; Ratcliff, Roger

    2013-01-01

    In the domain of discourse processing, it has been claimed that older adults (60-0-year-olds) are less likely to encode and remember some kinds of information from texts than young adults. The experiment described here shows that they do make a particular kind of inference to the same extent that college-age adults do. The inferences examined were…

  6. The use of urinary proteomics in the assessment of suitability of mouse models for ageing

    PubMed Central

    Nkuipou-Kenfack, Esther; Schanstra, Joost P.; Bajwa, Seerat; Pejchinovski, Martin; Vinel, Claire; Dray, Cédric; Valet, Philippe; Bascands, Jean-Loup; Vlahou, Antonia; Koeck, Thomas; Borries, Melanie; Busch, Hauke; Bechtel-Walz, Wibke; Huber, Tobias B.; Rudolph, Karl L.; Pich, Andreas; Mischak, Harald; Zürbig, Petra

    2017-01-01

    Ageing is a complex process characterised by a systemic and progressive deterioration of biological functions. As ageing is associated with an increased prevalence of age-related chronic disorders, understanding its underlying molecular mechanisms can pave the way for therapeutic interventions and managing complications. Animal models such as mice are commonly used in ageing research as they have a shorter lifespan in comparison to humans and are also genetically close to humans. To assess the translatability of mouse ageing to human ageing, the urinary proteome in 89 wild-type (C57BL/6) mice aged between 8–96 weeks was investigated using capillary electrophoresis coupled to mass spectrometry (CE-MS). Using age as a continuous variable, 295 peptides significantly correlated with age in mice were identified. To investigate the relevance of using mouse models in human ageing studies, a comparison was performed with a previous correlation analysis using 1227 healthy subjects. In mice and humans, a decrease in urinary excretion of fibrillar collagens and an increase of uromodulin fragments was observed with advanced age. Of the 295 peptides correlating with age, 49 had a strong homology to the respective human age-related peptides. These ortholog peptides including several collagen (N = 44) and uromodulin (N = 5) fragments were used to generate an ageing classifier that was able to discriminate the age among both wild-type mice and healthy subjects. Additionally, the ageing classifier depicted that telomerase knock-out mice were older than their chronological age. Hence, with a focus on ortholog urinary peptides mouse ageing can be translated to human ageing. PMID:28199320

  7. Use of 3H/3He ages to evaluate and improve groundwater flow models in a complex buried-valley aquifer

    USGS Publications Warehouse

    Sheets, R.A.; Bair, E.S.; Rowe, G.L.

    1998-01-01

    Combined use of the tritium/helium 3 (3H/3He) dating technique and particle-tracking analysis can improve flow-model calibration. As shown at two sites in the Great Miami buried-valley aquifer in southwestern Ohio, the combined use of 3H/3He age dating and particle tracking led to a lower mean absolute error between measured heads and simulated heads than in the original calibrated models and/or between simulated travel times and 3H/3He ages. Apparent groundwater ages were obtained for water samples collected from 44 wells at two locations where previously constructed finite difference models of groundwater flow were available (Mound Plant and Wright-Patterson Air Force Base (WPAFB)). The two-layer Mound Plant model covers 11 km2 within the buried-valley aquifer. The WPAFB model has three layers and covers 262 km2 within the buried-valley aquifer and adjacent bedrock uplands. Sampled wells were chosen along flow paths determined from potentiometric maps or particle-tracking analyses. Water samples were collected at various depths within the aquifer. In the Mound Plant area, samples used for comparison of 3H/3He ages with simulated travel times were from wells completed in the uppermost model layer. Simulated travel times agreed well with 3H/3He ages. The mean absolute error (MAE) was 3.5 years. Agreement in ages at WPAFB decreased with increasing depth in the system. The MAEs were 1.63, 17.2, and 255 years for model layers 1, 2, and 3, respectively. Discrepancies between the simulated travel times and 3H/3He ages were assumed to be due to improper conceptualization or incorrect parameterization of the flow models. Selected conceptual and parameter modifications to the models resulted in improved agreement between 3H/3He ages and simulated travel times and between measured and simulated heads and flows.

  8. Application of the tripartite model to a complicated sample of residential youth with externalizing problems.

    PubMed

    Chin, Eu Gene; Ebesutani, Chad; Young, John

    2013-06-01

    The tripartite model of anxiety and depression has received strong support among child and adolescent populations. Clinical samples of children and adolescents in these studies, however, have usually been referred for treatment of anxiety and depression. This study investigated the fit of the tripartite model with a complicated sample of residential youths with externalizing problems. Structural Equation Modeling was used to test the tripartite model relationships between negative affect, positive affect, and mood symptoms. Multiple fit indices were used to provide a reliable and conservative evaluation of the model. As predicted, the tripartite model provided a good fit for symptoms of emotional disorders in this complicated sample of children and adolescents. Implications of these findings are discussed in terms of the utility of the tripartite model in understanding anxiety and depression in more diverse populations and recommendations for residential assessment.

  9. Modeling the Information Age Combat Model: An Agent-Based Simulation of Network Centric Operations

    NASA Technical Reports Server (NTRS)

    Deller, Sean; Rabadi, Ghaith A.; Bell, Michael I.; Bowling, Shannon R.; Tolk, Andreas

    2010-01-01

    The Information Age Combat Model (IACM) was introduced by Cares in 2005 to contribute to the development of an understanding of the influence of connectivity on force effectiveness that can eventually lead to quantitative prediction and guidelines for design and employment. The structure of the IACM makes it clear that the Perron-Frobenius Eigenvalue is a quantifiable metric with which to measure the organization of a networked force. The results of recent experiments presented in Deller, et aI., (2009) indicate that the value of the Perron-Frobenius Eigenvalue is a significant measurement of the performance of an Information Age combat force. This was accomplished through the innovative use of an agent-based simulation to model the IACM and represents an initial contribution towards a new generation of combat models that are net-centric instead of using the current platform-centric approach. This paper describes the intent, challenges, design, and initial results of this agent-based simulation model.

  10. Interpretation of stable isotope, denitrification, and groundwater age data for samples collected from Sandia National Laboratories /New Mexico (SNL/NM) Burn Site Groundwater Area of Concern

    SciTech Connect

    Madrid, V.; Singleton, M. J.; Visser, A.; Esser, B.

    2016-06-02

    This report combines and summarizes results for two groundwater-sampling events (October 2012 and October/November 2015) from the Sandia National Laboratories/New Mexico (SNL/NM) Burn Site Groundwater (BSG) Area of Concern (AOC) located in the Lurance Canyon Arroyo southeast of Albuquerque, NM in the Manzanita Mountains. The first phase of groundwater sampling occurred in October 2012 including samples from 19 wells at three separate sites that were analyzed by the Environmental Radiochemistry Laboratory at Lawrence Livermore National Laboratory as part of a nitrate Monitored Natural Attenuation (MNA) evaluation. The three sites (BSG, Technical Area-V, and Tijeras Arroyo) are shown on the regional hydrogeologic map and described in the Sandia Annual Groundwater Monitoring Report. The first phase of groundwater sampling included six monitoring wells at the Burn Site, eight monitoring wells at Technical Area-V, and five monitoring wells at Tijeras Arroyo. Each groundwater sample was analyzed using the two specialized analytical methods, age-dating and denitrification suites. In September 2015, a second phase of groundwater sampling took place at the Burn Site including 10 wells sampled and analyzed by the same two analytical suites. Five of the six wells sampled in 2012 were resampled in 2015. This report summarizes results from two sampling events in order to evaluate evidence for in situ denitrification, the average age of the groundwater, and the extent of recent recharge of the bedrock fracture system beneath the BSG AOC.

  11. All age-depth models are wrong, but are getting better

    NASA Astrophysics Data System (ADS)

    Trachsel, Mathias; Chipperfield, Joseph D.; Telford, Richard J.

    2015-04-01

    Construction of accurate age-depth relationships and realistic assessment of their uncertainties is one of the fundamental prerequisites for comparing and correlating Late Quaternary stratigraphic proxy records. Four widely used age-depth modelling routines: i) clam, ii) OxCal, iii) Bacon, and iv) Bchron were tested using radiocarbon dates simulated from varved sediment stratigraphies. All methods produced average age-depth models that were close to the true varve age, but the uncertainty estimation differed considerably among models. Age uncertainties were underestimated by clam, whereas age uncertainties produced by Bchron were too large. Using OxCal and Bacon, setting of model specific parameters influenced the estimated uncertainties, which varied from too large to too small. Still, compared to the study by Telford et al. (2004), the use of Bayesian age-depth models greatly improved on the assessment of uncertainties of age-depth models. Reference: Telford et al. (2004), All age-depth models are wrong: but how badly? Quaternary Science Reviews, 23,1-5.

  12. Preparing the workforce for healthy aging programs: the Skills for Healthy Aging Resources and Programs (SHARP) model.

    PubMed

    Frank, Janet C; Altpeter, Mary; Damron-Rodriguez, JoAnn; Driggers, Joann; Lachenmayr, Susan; Manning, Colleen; Martinez, Dana M; Price, Rachel M; Robinson, Patricia

    2014-10-01

    Current public health and aging service agency personnel have little training in gerontology, and virtually no training in evidence-based health promotion and disease management programs for older adults. These programs are rapidly becoming the future of our community-based long-term care support system. The purpose of this project was to develop and test a model community college career technical education program, Skills for Healthy Aging Resources and Programs (SHARP), for undergraduate college students, current personnel in aging service and community organizations, and others interested in retraining. A multidisciplinary cross-sector team from disciplines of public health, sociology, gerontology and nursing developed four competency-based courses that focus on healthy aging, behavior change strategies, program management, an internship, and an option for leader training in the Chronic Disease Self-Management Program. To enhance implementation and fidelity, intensive faculty development training was provided to all instructors and community agency partners. Baseline and postprogram evaluation of competencies for faculty and students was conducted. Process evaluation for both groups focused on satisfaction with the curricula and suggestions for program improvement. SHARP has been piloted five times at two community colleges. Trainees (n = 113) were primarily community college students (n = 108) and current aging service personnel (n = 5). Statistically significant improvements in all competencies were found for both faculty and students. Process evaluation outcomes identified the needed logical and component adaptations to enhance the feasibility of program implementation, dissemination, and student satisfaction. The SHARP program provides a well-tested, evidence-based effective model for addressing workforce preparation in support of healthy aging service program expansion and delivery.

  13. Budding yeast as a model organism to study the effects of age.

    PubMed

    Denoth Lippuner, Annina; Julou, Thomas; Barral, Yves

    2014-03-01

    Although a budding yeast culture can be propagated eternally, individual yeast cells age and eventually die. The detailed knowledge of this unicellular eukaryotic species as well as the powerful tools developed to study its physiology makes budding yeast an ideal model organism to study the mechanisms involved in aging. Considering both detrimental and positive aspects of age, we review changes occurring during aging both at the whole-cell level and at the intracellular level. The possible mechanisms allowing old cells to produce rejuvenated progeny are described in terms of accumulation and inheritance of aging factors. Based on the dynamic changes associated with age, we distinguish different stages of age: early age, during which changes do not impair cell growth; intermediate age, during which aging factors start to accumulate; and late age, which corresponds to the last divisions before death. For each aging factor, we examine its asymmetric segregation and whether it plays a causal role in aging. Using the example of caloric restriction, we describe how the aging process can be modulated at different levels and how changes in different organelles might interplay with each other. Finally, we discuss the beneficial aspects that might be associated with age.

  14. Sample Size Requirements in Single- and Multiphase Growth Mixture Models: A Monte Carlo Simulation Study

    ERIC Educational Resources Information Center

    Kim, Su-Young

    2012-01-01

    Just as growth mixture models are useful with single-phase longitudinal data, multiphase growth mixture models can be used with multiple-phase longitudinal data. One of the practically important issues in single- and multiphase growth mixture models is the sample size requirements for accurate estimation. In a Monte Carlo simulation study, the…

  15. A New Symptom Model for Autism Cross-Validated in an Independent Sample

    ERIC Educational Resources Information Center

    Boomsma, A.; Van Lang, N. D. J.; De Jonge, M. V.; De Bildt, A. A.; Van Engeland, H.; Minderaa, R. B.

    2008-01-01

    Background: Results from several studies indicated that a symptom model other than the DSM triad might better describe symptom domains of autism. The present study focused on a) investigating the stability of a new symptom model for autism by cross-validating it in an independent sample and b) examining the invariance of the model regarding three…

  16. A Comparison of Sequential Sampling Models for Two-Choice Reaction Time

    ERIC Educational Resources Information Center

    Ratcliff, Roger; Smith, Philip L.

    2004-01-01

    The authors evaluated 4 sequential sampling models for 2-choice decisions--the Wiener diffusion, Ornstein-Uhlenbeck (OU) diffusion, accumulator, and Poisson counter models--by fitting them to the response time (RT) distributions and accuracy data from 3 experiments. Each of the models was augmented with assumptions of variability across trials in…

  17. Phospholipase A2 – nexus of aging, oxidative stress, neuronal excitability, and functional decline of the aging nervous system? Insights from a snail model system of neuronal aging and age-associated memory impairment

    PubMed Central

    Hermann, Petra M.; Watson, Shawn N.; Wildering, Willem C.

    2014-01-01

    The aging brain undergoes a range of changes varying from subtle structural and physiological changes causing only minor functional decline under healthy normal aging conditions, to severe cognitive or neurological impairment associated with extensive loss of neurons and circuits due to age-associated neurodegenerative disease conditions. Understanding how biological aging processes affect the brain and how they contribute to the onset and progress of age-associated neurodegenerative diseases is a core research goal in contemporary neuroscience. This review focuses on the idea that changes in intrinsic neuronal electrical excitability associated with (per)oxidation of membrane lipids and activation of phospholipase A2 (PLA2) enzymes are an important mechanism of learning and memory failure under normal aging conditions. Specifically, in the context of this special issue on the biology of cognitive aging we portray the opportunities offered by the identifiable neurons and behaviorally characterized neural circuits of the freshwater snail Lymnaea stagnalis in neuronal aging research and recapitulate recent insights indicating a key role of lipid peroxidation-induced PLA2 as instruments of aging, oxidative stress and inflammation in age-associated neuronal and memory impairment in this model system. The findings are discussed in view of accumulating evidence suggesting involvement of analogous mechanisms in the etiology of age-associated dysfunction and disease of the human and mammalian brain. PMID:25538730

  18. The development of a ductility-based aging model for low temperature aged U-6Nb alloy

    SciTech Connect

    Bridges, B

    2005-03-24

    This study focuses on the ductility evaluation of low-temperature (100 and 200 C) aged U-6Nb alloy. The objective is to develop a ductility-based aging model to improve lifetime prediction for weapon components in the stockpile environment. Literature review shows that the work hardening n-value and the strain-rate hardening mvalue are the two most important metallurgical factors for the uniform and the post-uniform (necking) ductility control, respectively. Unfortunately, both n and m values of the U-6Nb alloy are lacking. The study shows that the total ductility of U-6Nb is dominated by the uniform ductility, which deteriorates in both 100 C and 200 C aging. Further analysis shows that the uniform ductility correlates well with the work hardening n-value of the later stage deformation in which dislocation-slip is the mechanism. The kinetics of the loss of uniform ductility and the associated reduction in work-hardening n-value in low temperature aging will be used for the development of a ductility-based aging model. The necking ductility appears to be a minor but significant factor in the total ductility of U-6Nb. It does not show a clear trend due to large data scatter. The uncertain nature of necking failure may always hinder a reliable measurement of necking ductility. Consequently, a precise measurement of strain-rate hardening m-value could be a viable alternative to model the metallurgical contribution to the necking ductility. The conventional strain rate step-change method and the ABI (Automated-Ball-Indentation) test both show promising result in m-value measurement.

  19. A comparison of levels of select minerals in scalp hair samples with estimated dietary intakes of these minerals in women of reproductive age.

    PubMed

    Suliburska, J

    2011-12-01

    The objective of this study was to evaluate daily intake of minerals and concentrations of minerals in hair in women of reproductive age. The study included 77 menstruating women, aged 35.9 ± 9.7 years. Subjects were divided into three groups according to age. All women were healthy. Hair samples were taken from several points of the occipital scalp. The content of minerals in hair samples was determined by flame atomic absorption spectrometry. Dietary intake of the analysed minerals was assayed on the basis of dietary intake interviews from three preceding days and evaluated using the dietetic computer programme. It was shown that calcium and iron daily intake by the women was below the recommended value. Only few women had low concentrations (below reference values) of magnesium, copper and zinc in hair. Statistically significant differences were shown between age groups. Generally, the concentrations of minerals in hair in the younger (19-30 years) and the older women (41-50 years) were higher than in hair of middle-aged women (31-40 years). The content of calcium, magnesium, iron and zinc in daily diets of women correlated inversely with copper level in their hair. Food products with good bioavailability of iron and calcium should be recommended for women of childbearing age in all age groups.

  20. Estimation of pyrethroid pesticide intake using regression modeling of food groups based on composite dietary samples.

    PubMed

    Michael, Larry C; Brown, G Gordon; Melnyk, Lisa Jo

    2016-11-01

    Population-based estimates of pesticide intake are needed to characterize exposure for particular demographic groups based on their dietary behaviors. Regression modeling performed on measurements of selected pesticides in composited duplicate diet samples allowed (1) estimation of pesticide intakes for a defined demographic community, and (2) comparison of dietary pesticide intakes between the composite and individual samples. Extant databases were useful for assigning individual samples to composites, but they could not provide the breadth of information needed to facilitate measurable levels in every composite. Composite sample measurements were found to be good predictors of pyrethroid pesticide levels in their individual sample constituents where sufficient measurements are available above the method detection limit. Statistical inference shows little evidence of differences between individual and composite measurements and suggests that regression modeling of food groups based on composite dietary samples may provide an effective tool for estimating dietary pesticide intake for a defined population.

  1. Incorporating harvest rates into the sex-age-kill model for white-tailed deer

    USGS Publications Warehouse

    Norton, Andrew S.; Diefenbach, Duane R.; Rosenberry, Christopher S.; Wallingford, Bret D.

    2013-01-01

    Although monitoring population trends is an essential component of game species management, wildlife managers rarely have complete counts of abundance. Often, they rely on population models to monitor population trends. As imperfect representations of real-world populations, models must be rigorously evaluated to be applied appropriately. Previous research has evaluated population models for white-tailed deer (Odocoileus virginianus); however, the precision and reliability of these models when tested against empirical measures of variability and bias largely is untested. We were able to statistically evaluate the Pennsylvania sex-age-kill (PASAK) population model using realistic error measured using data from 1,131 radiocollared white-tailed deer in Pennsylvania from 2002 to 2008. We used these data and harvest data (number killed, age-sex structure, etc.) to estimate precision of abundance estimates, identify the most efficient harvest data collection with respect to precision of parameter estimates, and evaluate PASAK model robustness to violation of assumptions. Median coefficient of variation (CV) estimates by Wildlife Management Unit, 13.2% in the most recent year, were slightly above benchmarks recommended for managing game species populations. Doubling reporting rates by hunters or doubling the number of deer checked by personnel in the field reduced median CVs to recommended levels. The PASAK model was robust to errors in estimates for adult male harvest rates but was sensitive to errors in subadult male harvest rates, especially in populations with lower harvest rates. In particular, an error in subadult (1.5-yr-old) male harvest rates resulted in the opposite error in subadult male, adult female, and juvenile population estimates. Also, evidence of a greater harvest probability for subadult female deer when compared with adult (≥2.5-yr-old) female deer resulted in a 9.5% underestimate of the population using the PASAK model. Because obtaining

  2. Simulation of Tritium Transport and Groundwater Age in a Variably Saturated 3D Model, Lake Rotorua Catchment, New Zealand

    NASA Astrophysics Data System (ADS)

    Daughney, C.; Toews, M. W.; Morgenstern, U.; Cornaton, F. J.; Jackson, B. M.

    2013-12-01

    Lake Rotorua is a focus of culture and tourism in New Zealand. The lake's water quality has declined since the 1970s, partly due to nutrient inputs that reach the lake via the groundwater system. Improved land use management within the catchment requires prediction of the spatial variations of groundwater transit time from land surface to the lake, and from this the prediction of current and future nutrient inflows to the lake. This study combines the two main methods currently available for determination of water age: numerical groundwater models and hydrological tracers. A steady-state 3D finite element model was constructed to simulate groundwater flow and transport of tritium and age at the catchment scale (555 km2). The model materials were defined using a 3D geologic model and included ignimbrites, rhyolites, alluvial and lake bottom sediments. The steady-state saturated groundwater flow model was calibrated using observed groundwater levels in boreholes (111 locations) and stream flow measurements from groundwater-fed streams and springs (61 locations). Hydraulic conductivities and Cauchy boundary conditions associated with the streams, springs and lake were parameterized. The transport parameters for the model were calibrated using 191 tritium samples from 105 locations (springs, streams and boreholes), with most locations having two sample dates. The transport model used steady-state flow, but simulated the transient transport and decay of tritium from rainfall recharge between 1945 and 2012. An additional 1D unsaturated sub-model was added to account for tritium decay from the ground surface to the water table. The sub-model is linked on top of the 3D model, and uses the water table depths and material properties from the 3D model. The adjustable calibration parameters for the transport model were porosity and van Genuchten parameters related to the unsaturated sub-models. Calibration of the flow model was achieved using a combination of automated least

  3. Estimation of pyrethroid pesticide intake using regression modeling of food groups based on composite dietary samples

    EPA Science Inventory

    Population-based estimates of pesticide intake are needed to characterize exposure for particular demographic groups based on their dietary behaviors. Regression modeling performed on measurements of selected pesticides in composited duplicate diet samples allowed (1) estimation ...

  4. Sample Size Requirements for Structural Equation Models: An Evaluation of Power, Bias, and Solution Propriety

    ERIC Educational Resources Information Center

    Wolf, Erika J.; Harrington, Kelly M.; Clark, Shaunna L.; Miller, Mark W.

    2013-01-01

    Determining sample size requirements for structural equation modeling (SEM) is a challenge often faced by investigators, peer reviewers, and grant writers. Recent years have seen a large increase in SEMs in the behavioral science literature, but consideration of sample size requirements for applied SEMs often relies on outdated rules-of-thumb.…

  5. Goodness of Fit Confirmatory Factor Analysis: The Effects of Sample Size and Model Parsimony.

    ERIC Educational Resources Information Center

    Marsh, Herbert W.; Balla, John

    The influence of sample size (N) and model parsimony on a set of 22 goodness of fit indices was investigated, including those typically used in confirmatory factor analysis and some recently developed indices. For sample data simulated from 2 known population data structures, values for 6 of 22 fit indices were reasonably independent of N and were…

  6. The Validity of the Five-Factor Model Prototypes for Personality Disorders in Two Clinical Samples

    ERIC Educational Resources Information Center

    Miller, Joshua D.; Reynolds, Sarah K.; Pilkonis, Paul A.

    2004-01-01

    The authors examined the validity of D. R. Lynam and T. A. Widiger's (2001) prototypes for personality disorders (PDs) derived from the facets of the 5-factor model (FFM) of personality in 2 clinical samples. In the 1st sample (N = 94), there was good agreement between the prototypes generated by experts and the profiles reported by patients.…

  7. Regularization Methods for Fitting Linear Models with Small Sample Sizes: Fitting the Lasso Estimator Using R

    ERIC Educational Resources Information Center

    Finch, W. Holmes; Finch, Maria E. Hernandez

    2016-01-01

    Researchers and data analysts are sometimes faced with the problem of very small samples, where the number of variables approaches or exceeds the overall sample size; i.e. high dimensional data. In such cases, standard statistical models such as regression or analysis of variance cannot be used, either because the resulting parameter estimates…

  8. Sample Size and Item Parameter Estimation Precision When Utilizing the One-Parameter "Rasch" Model

    ERIC Educational Resources Information Center

    Custer, Michael

    2015-01-01

    This study examines the relationship between sample size and item parameter estimation precision when utilizing the one-parameter model. Item parameter estimates are examined relative to "true" values by evaluating the decline in root mean squared deviation (RMSD) and the number of outliers as sample size increases. This occurs across…

  9. The Naive Intuitive Statistician: A Naive Sampling Model of Intuitive Confidence Intervals

    ERIC Educational Resources Information Center

    Juslin, Peter; Winman, Anders; Hansson, Patrik

    2007-01-01

    The perspective of the naive intuitive statistician is outlined and applied to explain overconfidence when people produce intuitive confidence intervals and why this format leads to more overconfidence than other formally equivalent formats. The naive sampling model implies that people accurately describe the sample information they have but are…

  10. Covariate analysis of survival data: a small-sample study of Cox's model

    SciTech Connect

    Johnson, M.E.; Tolley, H.D.; Bryson, M.C.; Goldman, A.S.

    1982-09-01

    Cox's proportional-hazards model is frequently used to adjust for covariate effects in survival-data analysis. The small-sample performances of the maximum partial likelihood estimators of the regression parameters in a two-covariate hazard function model are evaluated with respect to bias, variance, and power in hypothesis tests. Previous Monte Carlo work on the two-sample problem is reviewed.

  11. Implementation of an active aging model in Mexico for prevention and control of chronic diseases in the elderly

    PubMed Central

    Mendoza-Núñez, Víctor Manuel; Martínez-Maldonado, María de la Luz; Correa-Muñoz, Elsa

    2009-01-01

    Background World Health Organization cites among the main challenges of populational aging the dual disease burden: the greater risk of disability, and the need for care. In this sense, the most frequent chronic diseases during old age worldwide are high blood pressure, type 2 diabetes mellitus, cancer, arthritis, osteoporosis, depression, and dementia. Chronic disease-associated dependency represents an onerous sanitary and financial burden for the older adult, the family, and the health care system. Thus, it is necessary to propose community-level models for chronic disease prevention and control in old age. The aim of the present work is to show our experience in the development and implementation of a model for chronic disease prevention and control in old age at the community level under the active aging paradigm. Methods/Design A longitudinal study will be carried out in a sample of 400 elderly urban and rural-dwelling individuals residing in Hidalgo State, Mexico during five years. All participants will be enrolled in the model active aging. This establishes the formation of 40 gerontological promoters (GPs) from among the older adults themselves. The GPs function as mutual-help group coordinators (gerontological nuclei) and establish self-care and self-promotion actions for elderly well-being and social development. It will be conformed a big-net of social network of 40 mutual-help groups of ten elderly adults each one, in which self-care is a daily practice for chronic disease prevention and control, as well as for achieving maximal well-being and life quality in old age. Indicators of the model's impact will be (i) therapeutic adherence; (ii) the incidence of the main chronic diseases in old age; (iii) life expectancy without chronic diseases at 60 years of age; (iv) disability adjusted life years lost; (v) years of life lost due to premature mortality, and (vi) years lived with disability. Discussion We propose that the implementation of the model active

  12. Aging and strain softening model for episodic faulting

    USGS Publications Warehouse

    Stuart, W.D.

    1979-01-01

    Episodic slip on shallow crustal faults can be qualitatively explained by postulating a fault constitutive law that is the superposition of two limiting material responses: (1) strain softening after peak stress during large strain rates, and (2) strength (peak stress) recovery during aging at small strain rates. A single law permits a variety of seismic and aseismic phenomena to occur over a range of space and time scales. Specific cases are determined by the spatial variation of material constants, recent deformation history, crustal rigidity, and remote forcing. ?? 1979.

  13. Age at Onset of DSM-IV Pathological Gambling in a Non-Treatment Sample: Early- versus Later-Onset

    PubMed Central

    Black, Donald W.; Shaw, Martha; Coryell, William; Crowe, Raymond; McCormick, Brett; Allen, Jeff

    2015-01-01

    Background Pathological gambling (PG) is a prevalent and impairing public health problem. In this study we assessed age at onset in men and women with PG and compared the demographic and clinical picture of early- vs. later-onset individuals. We also compared age at onset in PG subjects and their first-degree relatives with PG. Method Subjects with DSM-IV PG were recruited during the conduct of two non-treatment clinical studies. Subjects were evaluated with structured interviews and validated questionnaires. Early-onset was defined as PG starting prior to age 33 years. Results Age at onset of PG in the 255 subjects ranged from 8 to 80 years with a mean (SD) of 34.0 (15.3) years. Men had an earlier onset than women. 84% of all subjects with PG had developed the disorder by age 50 years. Early-onset subjects were more likely to be male, to prefer action games, and to have substance use disorders, antisocial personality disorder, attention deficit/hyperactivity disorder, trait impulsiveness, and social anxiety disorder. Later-onset was more common in women and was associated with a preference for slots and a history of sexual abuse. Conclusions Age at onset of PG is bimodal and differs for men and women. Early- and later-onset PG have important demographic and clinical differences. The implications of the findings are discussed. PMID:25956751

  14. Age-Related Changes to Human Stratum Corneum Lipids Detected Using Time-of-Flight Secondary Ion Mass Spectrometry Following in Vivo Sampling.

    PubMed

    Starr, Nichola J; Johnson, Daniel J; Wibawa, Judata; Marlow, Ian; Bell, Mike; Barrett, David A; Scurr, David J

    2016-04-19

    This work demonstrates the ability to detect changes in both quantity and spatial distribution of human stratum corneum (SC) lipids from samples collected in vivo. The SC functions as the predominant barrier to the body, protecting against the penetration of xenobiotic substances. Changes to the SC lipid composition have been associated with barrier impairment and consequent skin disorders, and it is therefore important to monitor and quantify changes to this structure. This work demonstrates the first reported use of time-of-flight secondary ion mass spectrometry (ToF-SIMS) to assess physiological changes to human SC as a function of depth. This technique provides exceptional sensitivity and chemical specificity, allowing analysis of single tape stripped samples taken from volunteers. Using this methodology we were able to successfully identify chemical differences in human SC resulting from both intrinsic and extrinsic (photo) aging. Samples were collected from women of two age groups (under 27 and postmenopausal) and from two body sites with varying UV exposure (inner forearm and dorsal hand), and differences were identified using multivariate data analysis. The key finding was the significant aged-related increase and change in spatial distribution of the sterol cholesterol sulfate, a membrane stabilizing lipid. Significant changes in the prevalence of both lignoceric acid (C24:0) and hexacosanoic acid (C26:0) were also observed. This work describes previously unreported age-related chemical changes to human SC, providing an insight into aging mechanisms which may improve the design of both pharmaceutical and cosmetic topical products.

  15. Gender Ratio in a Clinical Population Sample, Age of Diagnosis and Duration of Assessment in Children and Adults with Autism Spectrum Disorder

    ERIC Educational Resources Information Center

    Rutherford, Marion; McKenzie, Karen; Johnson, Tess; Catchpole, Ciara; O'Hare, Anne; McClure, Iain; Forsyth, Kirsty; McCartney, Deborah; Murray, Aja

    2016-01-01

    This article reports on gender ratio, age of diagnosis and the duration of assessment procedures in autism spectrum disorder diagnosis in a national study which included all types of clinical services for children and adults. Findings are reported from a retrospective case note analysis undertaken with a representative sample of 150 Scottish…

  16. Behavioral, Emotional, and Academic Adjustment in a National Probability Sample of African American Children: Effects of Age, Gender, and Family Structure.

    ERIC Educational Resources Information Center

    Barbarin, Oscar A.; Soler, Robin E.

    1993-01-01

    Presents the frequency of behavioral, emotional, and academic adjustment problems in a national sample of 734 male and 724 female African-American children and adolescents from the National Health Interview Survey Child Health Supplement. Patterns of adjustment within specific groups also were examined, based on age, gender, socioeconomic status,…

  17. [An epidemiological study on dental-periodontal pathology in a sample of the school-age population of the city of Naples. II. Prevention and periodontal therapy].

    PubMed

    Matarasso, S; Dante, G; Cecere, E; Vadalà, R; Epifania, E

    1991-04-01

    The need for periodontal prevention and therapy was quantified according to the prevention of pathologies within the framework of an epidemiological study carried out on a sample population aged between 6 and 18 years. Data were collected using the CPITN method (WHO).

  18. The Association between Body Dissatisfaction and Depression: An Examination of the Moderating Effects of Gender, Age, and Weight Status in a Sample of Chinese Adolescents

    ERIC Educational Resources Information Center

    Chen, Gui; Guo, Guiping; Gong, Jingbo; Xiao, Shuiyuan

    2015-01-01

    The current study investigated the moderating effects of gender, age, and weight status on the relationship between body dissatisfaction and depression among adolescents. Data were collected on body dissatisfaction, depression, and demographic characteristics from a convenience sample of 1,101 adolescents (505 girls, 596 boys). The relationship…

  19. The African Turquoise Killifish: A Model for Exploring Vertebrate Aging and Diseases in the Fast Lane.

    PubMed

    Harel, Itamar; Brunet, Anne

    2015-01-01

    Why and how organisms age remains a mystery, and it defines one of the biggest challenges in biology. Aging is also the primary risk factor for many human pathologies, such as cancer, diabetes, cardiovascular diseases, and neurodegenerative diseases. Thus, manipulating the aging rate and potentially postponing the onset of these devastating diseases could have a tremendous impact on human health. Recent studies, relying primarily on nonvertebrate short-lived model systems, have shown the importance of both genetic and environmental factors in modulating the aging rate. However, relatively little is known about aging in vertebrates or what processes may be unique and specific to these complex organisms. Here we discuss how advances in genomics and genome editing have significantly expanded our ability to probe the aging process in a vertebrate system. We highlight recent findings from a naturally short-lived vertebrate, the African turquoise killifish, which provides an attractive platform for exploring mechanisms underlying vertebrate aging and age-related diseases.

  20. Age-distribution estimation for karst groundwater: Issues of parameterization and complexity in inverse modeling by convolution

    NASA Astrophysics Data System (ADS)

    Long, Andrew J.; Putnam, Larry D.

    2009-10-01

    SummaryConvolution modeling is useful for investigating the temporal distribution of groundwater age based on environmental tracers. The framework of a quasi-transient convolution model that is applicable to two-domain flow in karst aquifers is presented. The model was designed to provide an acceptable level of statistical confidence in parameter estimates when only chlorofluorocarbon (CFC) and tritium ( 3H) data are available. We show how inverse modeling and uncertainty assessment can be used to constrain model parameterization to a level warranted by available data while allowing major aspects of the flow system to be examined. As an example, the model was applied to water from a pumped well open to the Madison aquifer in central USA with input functions of CFC-11, CFC-12, CFC-113, and 3H, and was calibrated to several samples collected during a 16-year period. A bimodal age distribution was modeled to represent quick and slow flow less than 50 years old. The effects of pumping and hydraulic head on the relative volumetric fractions of these domains were found to be influential factors for transient flow. Quick flow and slow flow were estimated to be distributed mainly within the age ranges of 0-2 and 26-41 years, respectively. The fraction of long-term flow (>50 years) was estimated but was not dateable. The different tracers had different degrees of influence on parameter estimation and uncertainty assessments, where 3H was the most critical, and CFC-113 was least influential.

  1. Age-distribution estimation for karst groundwater: Issues of parameterization and complexity in inverse modeling by convolution

    USGS Publications Warehouse

    Long, A.J.; Putnam, L.D.

    2009-01-01

    Convolution modeling is useful for investigating the temporal distribution of groundwater age based on environmental tracers. The framework of a quasi-transient convolution model that is applicable to two-domain flow in karst aquifers is presented. The model was designed to provide an acceptable level of statistical confidence in parameter estimates when only chlorofluorocarbon (CFC) and tritium (3H) data are available. We show how inverse modeling and uncertaint