Science.gov

Sample records for age structure growth

  1. Notes on the Age of Maternity, Population Growth and Family Structure in the Past

    ERIC Educational Resources Information Center

    Mendels, Franklin F.

    1978-01-01

    Emphasizes that the age of marriage was effective in determining the birth rate and the rate of population growth; measures the magnitude of the effects of the age of marriage; and offers some observations on the relationships between age of marriage, age of male and female fertility, and family structure. (Author)

  2. Socio-Demographic Determinants of Economic Growth: Age-Structure, Preindustrial Heritage and Sociolinguistic Integration

    ERIC Educational Resources Information Center

    Crenshaw, Edward; Robison, Kristopher

    2010-01-01

    This study establishes a socio-demographic theory of international development derived from selected classical and contemporary sociological theories. Four hypotheses are tested: (1. population growth's effect on development depends on age-structure; (2. historic population density (used here as an indicator of preindustrial social complexity)…

  3. Analysis of Fish Age Structure and Growth in the Illinois River

    DTIC Science & Technology

    2007-06-01

    knowing the conditions that promote Biotic factors include size, quality, and availability desired growth and age structure for a particular of food ...collected for each year determination, otoliths were soaked in glycerin , of its life using back-calculated mean length-at- placed on a dark background

  4. Age structure and capital dilution effects in neo-classical growth models.

    PubMed

    Blanchet, D

    1988-01-01

    Economists often over estimate capital dilution effects when applying neoclassical growth models which use age structured population and depreciation of capital stock. This occurs because capital stock is improperly characterized. A standard model which assumes a constant depreciation of capital intimates that a population growth rate equal to a negative constant savings ratio is preferable to any higher growth rate. Growth rates which are lower than a negative constant savings ratio suggest an ever growing capital/labor ratio and an ever growing standard of living, even if people do not save. This is suggested because the natural reduction of the capital stock through depreciation is slower than the population decrease which is simply unrealistic. This model overlooks the fact that low or negative growth rates result in an ageing of the capital stock, and this ageing subsequently results in an increase of the overall rate of capital depreciation. In that overly simplistic model, depreciation was assumed independent of the age of the captial stock. Incorporating depreciation as a variable into a model allows a more symmetric treatment of capital. Using models with heterogenous capital, this article explores what occurs when more than 1 kind of capital good is involved in production and when these various captial goods have different lengths of life. Applying economic models, it also examines what occurs when the length of life of capital may vary. These variations correct the negative impact that population growth can have on per capital production and consumption.

  5. [Age structure and growth pattern of Polytrichum juniperum populations in a mire of Changbai Mountains].

    PubMed

    Bu, Zhaojun; Yan, Yunfei; Dai, Dan; Wang, Xianwei

    2005-01-01

    In this paper, the age structure and growth pattern of two Polytrichum juniperum populations with and without sporophytes in Hani mire of Changbai Mountains were studied by 'innate annual marker' method. The ramets of both populations were composed of 6 age classes, and their quantity and biomass showed a declining age structure, which was more obvious in the sporophyte produced population. No significant difference of biomass was found (P > 0.05) between the two populations. The dry material accumulation of the ramets in both populations increased with aging, and showed similar patterns of linear function. The ramets mean height of sporophyte-produced population was 6.17% shorter (P < 0.05) than the another, because sporophyte production limited the height growth. The ramets mean height also increased with aging, and showed similar patterns of linear function. In non-sporophyte produced population, the variation coefficient of ramets height was only 2.44%, which indicated the significance of similar height for ramets survival. In sporophyte produced population, the variation coefficient of ramets height was 25.07%, while that of ramets biomass was 8.25%, suggesting the significance of similar biomass to the reproduction of population. The biomass of ramets had a significantly positive correlation with height in both populations (P < 0.001), and no allometric growth was showed.

  6. Age, growth and population structure of invasive lionfish (Pterois volitans/miles) in northeast Florida using a length-based, age-structured population model

    PubMed Central

    2016-01-01

    The effective management of invasive species requires detailed understanding of the invader’s life history. This information is essential for modeling population growth and predicting rates of expansion, quantifying ecological impacts and assessing the efficacy of removal and control strategies. Indo-Pacific lionfish (Pterois volitans/miles) have rapidly invaded the western Atlantic, Gulf of Mexico and Caribbean Sea with documented negative impacts on native ecosystems. To better understand the life history of this species, we developed and validated a length-based, age-structured model to investigate age, growth and population structure in northeast Florida. The main findings of this study were: (1) lionfish exhibited rapid growth with seasonal variation in growth rates; (2) distinct cohorts were clearly identifiable in the length-frequency data, suggesting that lionfish are recruiting during a relatively short period in summer; and (3) the majority of lionfish were less than two years old with no lionfish older than three years of age, which may be the result of culling efforts as well as ontogenetic habitat shifts to deeper water. PMID:27920953

  7. Age, growth and population structure of invasive lionfish (Pterois volitans/miles) in northeast Florida using a length-based, age-structured population model.

    PubMed

    Johnson, Eric G; Swenarton, Mary Katherine

    2016-01-01

    The effective management of invasive species requires detailed understanding of the invader's life history. This information is essential for modeling population growth and predicting rates of expansion, quantifying ecological impacts and assessing the efficacy of removal and control strategies. Indo-Pacific lionfish (Pterois volitans/miles) have rapidly invaded the western Atlantic, Gulf of Mexico and Caribbean Sea with documented negative impacts on native ecosystems. To better understand the life history of this species, we developed and validated a length-based, age-structured model to investigate age, growth and population structure in northeast Florida. The main findings of this study were: (1) lionfish exhibited rapid growth with seasonal variation in growth rates; (2) distinct cohorts were clearly identifiable in the length-frequency data, suggesting that lionfish are recruiting during a relatively short period in summer; and (3) the majority of lionfish were less than two years old with no lionfish older than three years of age, which may be the result of culling efforts as well as ontogenetic habitat shifts to deeper water.

  8. Geographic variation in age, growth and size structure of Percilia irwini from south-central Chile.

    PubMed

    Aedo, J R; Belk, M C; Habit, E M

    2009-01-01

    Percilia irwini from the Andalién and Biobío River basins of south-central Chile exhibited a mean age of 1.4 years with a maximum age of 4 years. Size at age differed among river zones and males were 10% larger than females at all ages. Compared to other locations, populations of P. irwini inhabiting areas subject to industrial and domestic effluents exhibited smaller size structure.

  9. Anomalous Growth of Aging Populations

    NASA Astrophysics Data System (ADS)

    Grebenkov, Denis S.

    2016-04-01

    We consider a discrete-time population dynamics with age-dependent structure. At every time step, one of the alive individuals from the population is chosen randomly and removed with probability q_k depending on its age, whereas a new individual of age 1 is born with probability r. The model can also describe a single queue in which the service order is random while the service efficiency depends on a customer's "age" in the queue. We propose a mean field approximation to investigate the long-time asymptotic behavior of the mean population size. The age dependence is shown to lead to anomalous power-law growth of the population at the critical regime. The scaling exponent is determined by the asymptotic behavior of the probabilities q_k at large k. The mean field approximation is validated by Monte Carlo simulations.

  10. Effects of chemical contaminants on growth, age-structure, and reproduction of Mytilus edulis complex from Puget sound, Washington.

    PubMed

    Kagley, Anna N; Kardong, Kyle E; Snider, Robert G; Casillas, Edmundo

    2014-07-01

    Bivalves are used as sentinel species to detect chemical contaminants in the marine environment, but biological effects on indigenous populations that result from chemical exposure are largely unknown. We assessed age-weight, length-weight relationships, age structure, and reproductive status (i.e. fecundity, egg size) of the blue mussel Mytilus edulis complex from six sites in central Puget Sound, Washington, and one site in the relatively pristine area of northern Puget Sound. Results of this study suggest that mussels from urban areas of Puget Sound exhibit a lower growth rate, altered population age-structure, and potential reproductive impairment as a result of exposure to chemical contaminants. These findings support the use of mussels as sentinel species to assess the biological effects of contaminants on invertebrate populations.

  11. Decomposing variation in population growth into contributions from environment and phenotypes in an age-structured population.

    PubMed

    Pelletier, Fanie; Moyes, Kelly; Clutton-Brock, Tim H; Coulson, Tim

    2012-01-22

    Evaluating the relative importance of ecological drivers responsible for natural population fluctuations in size is challenging. Longitudinal studies where most individuals are monitored from birth to death and where environmental conditions are known provide a valuable resource to characterize complex ecological interactions. We used a recently developed approach to decompose the observed fluctuation in population growth of the red deer population on the Isle of Rum into contributions from climate, density and their interaction and to quantify their relative importance. We also quantified the contribution of individual covariates, including phenotypic and life-history traits, to population growth. Fluctuations in composition in age and sex classes ((st)age structure) of the population contributed substantially to the population dynamics. Density, climate, birth weight and reproductive status contributed less and approximately equally to the population growth. Our results support the contention that fluctuations in the population's (st)age structure have important consequences for population dynamics and underline the importance of including information on population composition to understand the effect of human-driven changes on population performance of long-lived species.

  12. Growth Hormone and Aging

    DTIC Science & Technology

    2000-08-01

    GH to animals of 24 months of replacement therapy in hypopituitary adults on age elicited beneficial effects in the same way as lipid metabolism and...carbohydrate tolerance. those seen in humans. Animals treated during one J Clin Endocrinol Metab,80:356-363 (1995). month with 2 UI of GH

  13. Growth and Age-Related Abnormalities in Cortical Structure and Fracture Risk

    PubMed Central

    2015-01-01

    Vertebral fractures and trabecular bone loss have dominated thinking and research into the pathogenesis and the structural basis of bone fragility during the last 70 years. However, 80% of all fractures are non-vertebral and occur at regions assembled using large amounts of cortical bone; only 20% of fractures are vertebral. Moreover, ~80% of the skeleton is cortical and ~70% of all bone loss is cortical even though trabecular bone is lost more rapidly than cortical bone. Bone is lost because remodelling becomes unbalanced after midlife. Most cortical bone loss occurs by intracortical, not endocortical remodelling. Each remodelling event removes more bone than deposited enlarging existing canals which eventually coalesce eroding and thinning the cortex from 'within.' Thus, there is a need to study the decay of cortical as well as trabecular bone, and to develop drugs that restore the strength of both types of bone. It is now possible to accurately quantify cortical porosity and trabecular decay in vivo. The challenges still to be met are to determine whether measurement of porosity identifies persons at risk for fracture, whether this approach is compliments information obtained using bone densitometry, and whether changes in cortical porosity and other microstructural traits have the sensitivity to serve as surrogates of treatment success or failure. PMID:26394727

  14. The effect of clinorotation on structural and functional organization of assimilative tissues, cells and growth regulator activity in orchids of different age

    NASA Astrophysics Data System (ADS)

    Cherevchenko, T.; Zaimenko, N.; Sitnyanska, N.; Majko, T.; Grishko, M. M.

    Ultrastructural analyses of assimilative tissues of the orchids, Cymbidium hybridum and Doritis pulcherrima, show that, in plants of different age, chloroplasts differ in structure and stage of membrane system development. Variability was found in the number, size and electron density of plastoglobuli, and in the orientation and length of thylakoid membranes. We consider significant the increase of the plastoglobuli which completely fill the stroma of chloroplasts in cells of old leaves and, under conditions of clinorotation (using a horizontal clinostat at 3 r.p.m.), are able to block membrane function. In the early stages of orchid plant development, the content of substances with auxin-like activity (as judged by bioassay) in the leaves was low, but increased with age. Clinorotation resulted in a sharp decrease of their content. There was a concomitant increase in the content of growth inhibitors of a phenolic nature.

  15. Age-Specific Correlates of Child Growth.

    PubMed

    Rieger, Matthias; Trommlerová, Sofia Karina

    2016-02-01

    Growth faltering describes a widespread phenomenon that height- and weight-for-age of children in developing countries collapse rapidly in the first two years of life. We study age-specific correlates of child nutrition using Demographic and Health Surveys from 56 developing countries to shed light on the potential drivers of growth faltering. Applying nonparametric techniques and exploiting within-mother variation, we find that maternal and household factors predict best the observed shifts and bends in child nutrition age curves. The documented interaction between age and maternal characteristics further underlines the need not only to provide nutritional support during the first years of life but also to improve maternal conditions.

  16. Growth, ageing and scaling laws of coronary arterial trees.

    PubMed

    Chen, Xi; Niu, Pei; Niu, Xiaolong; Shen, Wenzeng; Duan, Fei; Ding, Liang; Wei, Xiliang; Gong, Yanjun; Huo, Yong; Kassab, Ghassan S; Tan, Wenchang; Huo, Yunlong

    2015-12-06

    Despite the well-known design principles of vascular systems, it is unclear whether the vascular arterial tree obeys some scaling constraints during normal growth and ageing in a given species. Based on the micro-computed tomography measurements of coronary arterial trees in mice at different ages (one week to more than eight months), we show a constant exponent of 3/4, but age-dependent scaling coefficients in a length-volume scaling law (Lc=K(length-volume) · Vc³/⁴; Lc is the crown length, Vc is the crown volume, K(length-volume) is the age-dependent scaling coefficient) during normal growth and ageing. The constant 3/4 exponent represents the self-similar fractal-like branching pattern (i.e. basic mechanism to regulate the development of vascular trees within a species), whereas the age-dependent scaling coefficients characterize the structural growth or resorption of vascular trees during normal growth or ageing, respectively. This study enhances the understanding of age-associated changes in vascular structure and function.

  17. Structural aging program status report

    SciTech Connect

    Naus, D.J.; Oland, C.B.; Ellingwood, B.; Graves, H.L. III

    1994-12-31

    Research is being conducted at the Oak Ridge National Laboratory under Nuclear Regulatory Commission (USNRC) sponsorship to address aging management of safety-related concrete structures. Documentation is being prepared to provide the USNRC with potential structural safety issues and acceptance criteria for use in continued service evaluations of nuclear power plants. Program accomplishments have included development of the Structural Materials Information Center containing data and information on the time variation of 144 material properties under the influence of pertinent environmental stressors or aging factors, performance assessments of reinforced concrete structures in several United Kingdom nuclear power facilities, evaluation of European and North American repair practices for concrete, an evaluation of factors affecting the corrosion of metals embedded in concrete, and application of the time-dependent reliability methodology to reinforced concrete flexure and shear structural elements to investigate the role of in-service inspection and repair on their probability of failure.

  18. Structural aging program status report

    SciTech Connect

    Naus, D.J.; Oland, C.B.; Ellingwood, B.

    1995-04-01

    Research is being conducted at the Oak Ridge National Laboratory (ORNL) under U.S. Nuclear Regulatory Commission (USNRC) sponsorship to address aging management of safety-related concrete structures. Documentation is being prepared to provide the USNRC with potential structural safety issues and acceptance criteria for use in continued service evaluations of nuclear power plants. Program accomplishments have included development of the Structural Materials Information Center containing data and information of the time variation of 144 material properties under the influence of pertinent environmental stressors of aging factors, performance assessments of reinforced concrete structures in several United Kingdom nuclear power facilities, evaluation of European and North American repair practices for concrete, an evaluation of factors affecting the corrosion of metals embedded in concrete, and application of the time-dependent reliability methodology to reinforced concrete flexure and shear structural elements to investigate the role of in-service inspection and repair on their probability of failure.

  19. Estimating survival rates with age-structure data

    USGS Publications Warehouse

    Udevitz, M.S.; Ballachey, B.E.

    1998-01-01

    We developed a general statistical model that provides a comprehensive framework for inference about survival rates based on standing age-structure and ages-at-death data. Previously available estimators are maximum likelihood under the general model, but they use only 1 type of data and require the assumption of a stable age structure and a known population growth rate. We used the general model to derive new survival rate estimators that use both types of data and require only the assumption of a stable age structure or a known population growth rate. Our likelihood-based approach allows use of standard model-selection procedures to test hypotheses about age-structure stability, population growth rates, and age-related patterns in survival. We used this approach to estimate survival rates for female sea otters (Enhydra lutris) in Prince William Sound, Alaska.

  20. Growth factors, aging and age-related diseases.

    PubMed

    Balasubramanian, Priya; Longo, Valter D

    2016-06-01

    Simple organisms including yeast and flies with mutations in the IGF-1 and Tor-S6K pathways are dwarfs, are highly protected from toxins, and survive up to 3 times longer. Similarly, dwarf mice with deficiencies in the growth hormone-IGF-I axis are also long lived and protected from diseases. We recently reported that humans with Growth Hormone Receptor Deficiency (GHRD) rarely develop cancer or diabetes. These findings are in agreement with the effect of defects in the Tor-S6K pathways in causing dwarfism and protection of DNA. Because protein restriction reduces both GHR-IGF-1 axis and Tor-S6K activity, we examined links between protein intake, disease, and mortality in over 6000 US subjects in the NHANES CDC database. Respondents aged 50-65 reporting a high protein intake displayed an increase in IGF-I levels, a 75% increased risk of overall mortality and a 3-4 fold increased risk of cancer mortality in agreement with findings in mouse experiments. These studies point to a conserved link between proteins and amino acids, GHR-IGF-1/insulin, Tor-S6k signaling, aging, and diseases.

  1. Age and growth dynamics of Tyrannosaurus rex.

    PubMed

    Horner, John R; Padian, Kevin

    2004-09-22

    Tyrannosaurus rex is the most commonly found North American latest Cretaceous theropod, but until the 1980s only five specimens had been discovered, and no more than six have received a full description. Consequently there has been little information on how old Tyrannosaurus specimens were at maturity or death. Histological analysis of seven individuals provided, for the first time, an opportunity to assess the age represented by the bone cortex, to estimate the average individual age of these skeletons, to determine whether they represented fully grown individuals, and to predict their individual longevity. Though a range of ages (15-25 years) was found for the specimens studied, the seven individuals demonstrate that T. rex reached effectively full size in less than 20 years. The growth rate of T. rex was comparable to that of the African elephant, which has a similar mass and time to maturity. Some of the known specimens of T. rex did not quite reach full size; others do not seem to have survived long after achieving it.

  2. Growth hormone in the aging male.

    PubMed

    Sattler, Fred R

    2013-08-01

    Secretion of growth hormone (GH) and IGF-1 levels decline during advancing years-of-life. These changes (somatopause) are associated with loss of vitality, muscle mass, physical function, together with the occurrence of frailty, central adiposity, cardiovascular complications, and deterioration of mental function. For GH treatment to be considered for anti-aging, improved longevity, organ-specific function, or quality of life should be demonstrable. A limited number of controlled studies suggest that GH supplementation in older men increases lean mass by ∼2 kg with similar reductions in fat mass. There is little evidence that GH treatment improves muscle strength and performance (e.g. walking speed or ability to climb stairs) or quality of life. The GHRH agonist (tesamorelin) restores normal GH pulsatility and amplitude, selectively reduces visceral fat, intima media thickness and triglycerides, and improves cognitive function in older persons. This report critically reviews the potential for GH augmentation during aging with emphasis on men since women appear more resistant to treatment.

  3. Nonlinear structural crack growth monitoring

    DOEpatents

    Welch, Donald E.; Hively, Lee M.; Holdaway, Ray F.

    2002-01-01

    A method and apparatus are provided for the detection, through nonlinear manipulation of data, of an indicator of imminent failure due to crack growth in structural elements. The method is a process of determining energy consumption due to crack growth and correlating the energy consumption with physical phenomena indicative of a failure event. The apparatus includes sensors for sensing physical data factors, processors or the like for computing a relationship between the physical data factors and phenomena indicative of the failure event, and apparatus for providing notification of the characteristics and extent of such phenomena.

  4. Growth hormone, insulin-like growth factor-1 and the aging brain.

    PubMed

    Ashpole, Nicole M; Sanders, Jessica E; Hodges, Erik L; Yan, Han; Sonntag, William E

    2015-08-01

    Growth hormone (GH) and insulin-like growth factor (IGF)-1 regulate the development and function of cells throughout the body. Several clinical diseases that result in a decline in physical and mental functions are marked by mutations that disrupt GH or IGF-1 signaling. During the lifespan there is a robust decrease in both GH and IGF-1. Because GH and IGF-1 are master regulators of cellular function, impaired GH and IGF-1 signaling in aging/disease states leads to significant alterations in tissue structure and function, especially within the brain. This review is intended to highlight the effects of the GH and IGF-1 on neuronal structure, function, and plasticity. Furthermore, we address several potential mechanisms through which the age-related reductions in GH and IGF-1 affect cognition. Together, the studies reviewed here highlight the importance of maintaining GH and IGF-1 signaling in order to sustain proper brain function throughout the lifespan.

  5. Human Growth Hormone (HGH): Does It Slow Aging?

    MedlinePlus

    Healthy Lifestyle Healthy aging Human growth hormone is described by some as the key to slowing the aging ... about proven ways to improve your health. Remember, healthy lifestyle choices — such as eating a healthy diet and ...

  6. Disease spread in age structured populations with maternal age effects.

    PubMed

    Clark, Jessica; Garbutt, Jennie S; McNally, Luke; Little, Tom J

    2017-04-01

    Fundamental ecological processes, such as extrinsic mortality, determine population age structure. This influences disease spread when individuals of different ages differ in susceptibility or when maternal age determines offspring susceptibility. We show that Daphnia magna offspring born to young mothers are more susceptible than those born to older mothers, and consider this alongside previous observations that susceptibility declines with age in this system. We used a susceptible-infected compartmental model to investigate how age-specific susceptibility and maternal age effects on offspring susceptibility interact with demographic factors affecting disease spread. Our results show a scenario where an increase in extrinsic mortality drives an increase in transmission potential. Thus, we identify a realistic context in which age effects and maternal effects produce conditions favouring disease transmission.

  7. Age, growth rates, and paleoclimate studies of deep sea corals

    USGS Publications Warehouse

    Prouty, Nancy G; Roark, E. Brendan; Andrews, Allen; Robinson, Laura; Hill, Tessa; Sherwood, Owen; Williams, Branwen; Guilderson, Thomas P.; Fallon, Stewart

    2015-01-01

    Deep-water corals are some of the slowest growing, longest-lived skeletal accreting marine organisms. These habitat-forming species support diverse faunal assemblages that include commercially and ecologically important organisms. Therefore, effective management and conservation strategies for deep-sea corals can be informed by precise and accurate age, growth rate, and lifespan characteristics for proper assessment of vulnerability and recovery from perturbations. This is especially true for the small number of commercially valuable, and potentially endangered, species that are part of the black and precious coral fisheries (Tsounis et al. 2010). In addition to evaluating time scales of recovery from disturbance or exploitation, accurate age and growth estimates are essential for understanding the life history and ecology of these habitat-forming corals. Given that longevity is a key factor for population maintenance and fishery sustainability, partly due to limited and complex genetic flow among coral populations separated by great distances, accurate age structure for these deep-sea coral communities is essential for proper, long-term resource management.

  8. Crack Growth-Based Predictive Methodology for the Maintenance of the Structural Integrity of Repaired and Nonrepaired Aging Engine Stationary Components

    DTIC Science & Technology

    1999-04-01

    by its reduction in area. Inconel 718 -(IN718) Kb Specimen-A rectangular cross section test specimen used for crack growth testing which best represents...GEAE contract to look at weldability of wrought and cast Inconel 718 (IN718) material after exposure to the aforementioned 15 and 30 simulated repair...COMPOSITION WROUGHT PROGRAM MATERIAL AFTER 40 HEAT TREATMENT CYCLES 100 90 - Inconel 718 C995HD40 Tpeak= 1260 °C S70 NDT=1105 ’C60 NST=1304 0C ឬ- DRT=1050 °C

  9. Funding growth in an age of austerity.

    PubMed

    Hamel, Gary; Getz, Gary

    2004-01-01

    Everyone knows that corporate growth--true growth, not just agglomeration--springs from innovation. And the common wisdom is that companies must spend lavishly on R&D if they are to innovate at all. But in these fiscally cautious times, where every line item of every budget in every company is under intense scrutiny, many organizations are doing just the opposite. They tighten their belts, subject nascent product-development programs to rigorous screening, and train R&D staffers to think in business terms so the researchers will be better able to decide whether an idea for a product or service is worth pursuing in the first place. Such efficiency measures are commendable, say authors Gary Hamel and Gary Getz. But frugality is not a growth strategy, they point out, and, in truth, there is very little correlation between corporate performance and the amount spent on innovation. Companies like Southwest, Cemex, and Shell Chemicals have shown that businesses don't have to spend a fortune on R&D to reap the benefits of innovation. To produce more growth per dollar invested, companies must produce more innovation per dollar invested. Hamel and Getz explain how businesses can dramatically improve their innovation yields. They offer these five imperatives: Increase the number of innovators among existing employees (whatever their job titles) by involving them in innovation processes and events. Focus on developing truly radical ideas--ones that change customers' expectations and behaviors and industry economics--not just incremental ideas. Look for innovation sources outside the organization, as well as inside. Increase the learning from small, low-risk experiments. And commit to long-term, consistent development efforts.

  10. Density dependence in an age-structured population of great tits: identifying the critical age classes.

    PubMed

    Gamelon, Marlène; Grøtan, Vidar; Engen, Steinar; Bjørkvoll, Eirin; Visser, Marcel E; Saether, Bernt-Erik

    2016-09-01

    Classical approaches for the analyses of density dependence assume that all the individuals in a population equally respond and equally contribute to density dependence. However, in age-structured populations, individuals of different ages may differ in their responses to changes in population size and how they contribute to density dependence affecting the growth rate of the whole population. Here we apply the concept of critical age classes, i.e., a specific scalar function that describes how one or a combination of several age classes affect the demographic rates negatively, in order to examine how total density dependence acting on the population growth rate depends on the age-specific population sizes. In a 38-yr dataset of an age-structured great tit (Parus major) population, we find that the age classes, including the youngest breeding females, were the critical age classes for density regulation. These age classes correspond to new breeders that attempt to take a territory and that have the strongest competitive effect on other breeding females. They strongly affected population growth rate and reduced recruitment and survival rates of all breeding females. We also show that depending on their age class, females may differently respond to varying density. In particular, the negative effect of the number of breeding females was stronger on recruitment rate of the youngest breeding females. These findings question the classical assumptions that all the individuals of a population can be treated as having an equal contribution to density regulation and that the effect of the number of individuals is age independent. Our results improve our understanding of density regulation in natural populations.

  11. Structural Imaging Measures of Brain Aging

    PubMed Central

    Lockhart, Samuel N.

    2014-01-01

    During the course of normal aging, biological changes occur in the brain that are associated with changes in cognitive ability. This review presents data from neuroimaging studies of primarily “normal” or healthy brain aging. As such, we focus on research in unimpaired or nondemented older adults, but also include findings from lifespan studies that include younger and middle aged individuals as well as from populations with prodromal or clinically symptomatic disease such as cerebrovascular or Alzheimer’s disease. This review predominantly addresses structural MRI biomarkers, such as volumetric or thickness measures from anatomical images, and measures of white matter injury and integrity respectively from FLAIR or DTI, and includes complementary data from PET and cognitive or clinical testing as appropriate. The findings reveal highly consistent age-related differences in brain structure, particularly frontal lobe and medial temporal regions that are also accompanied by age-related differences in frontal and medial temporal lobe mediated cognitive abilities. Newer findings also suggest that degeneration of specific white matter tracts such as those passing through the genu and splenium of the corpus callosum may also be related to age-related differences in cognitive performance. Interpretation of these findings, however, must be tempered by the fact that comorbid diseases such as cerebrovascular and Alzheimer’s disease also increase in prevalence with advancing age. As such, this review discusses challenges related to interpretation of current theories of cognitive aging in light of the common occurrence of these later-life diseases. Understanding the differences between “Normal” and “Healthy” brain aging and identifying potential modifiable risk factors for brain aging is critical to inform potential treatments to stall or reverse the effects of brain aging and possibly extend cognitive health for our aging society. PMID:25146995

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

    USGS Publications Warehouse

    Eaton, Mitchell J.; Link, William A.

    2011-01-01

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

  13. Growth hormone prevents neuronal loss in the aged rat hippocampus.

    PubMed

    Azcoitia, Iñigo; Perez-Martin, Margarita; Salazar, Veronica; Castillo, Carmen; Ariznavarreta, Carmen; Garcia-Segura, Luis M; Tresguerres, Jesus A F

    2005-05-01

    Decline of growth hormone (GH) with aging is associated to memory and cognitive alterations. In this study, the number of neurons in the hilus of the dentate gyrus has been assessed in male and female Wistar rats at 3, 6, 12, 14, 18, 22 and 24 months of age, using the optical fractionator method. Male rats had more neurons than females at all the ages studied. Significant neuronal loss was observed in both sexes between 22 and 24 months of age. In a second experiment, 22 month-old male and female rats were treated for 10 weeks with 2 mg/kg/day of GH or saline. At 24 months of age, animals treated with GH had more neurons in the hilus than animals treated with saline. These findings indicate that GH is neuroprotective in old animals and that its administration may ameliorate neuronal alterations associated to aging.

  14. Do otolith increments allow correct inferences about age and growth of coral reef fishes?

    NASA Astrophysics Data System (ADS)

    Booth, D. J.

    2014-03-01

    Otolith increment structure is widely used to estimate age and growth of marine fishes. Here, I test the accuracy of the long-term otolith increment analysis of the lemon damselfish Pomacentrus moluccensis to describe age and growth characteristics. I compare the number of putative annual otolith increments (as a proxy for actual age) and widths of these increments (as proxies for somatic growth) with actual tagged fish-length data, based on a 6-year dataset, the longest time course for a coral reef fish. Estimated age from otoliths corresponded closely with actual age in all cases, confirming annual increment formation. However, otolith increment widths were poor proxies for actual growth in length [linear regression r 2 = 0.44-0.90, n = 6 fish] and were clearly of limited value in estimating annual growth. Up to 60 % of the annual growth variation was missed using otolith increments, suggesting the long-term back calculations of otolith growth characteristics of reef fish populations should be interpreted with caution.

  15. Radiocarbon Based Ages and Growth Rates: Hawaiian Deep Sea Corals

    SciTech Connect

    Roark, E B; Guilderson, T P; Dunbar, R B; Ingram, B L

    2006-01-13

    The radial growth rates and ages of three different groups of Hawaiian deep-sea 'corals' were determined using radiocarbon measurements. Specimens of Corallium secundum, Gerardia sp., and Leiopathes glaberrima, were collected from 450 {+-} 40 m at the Makapuu deep-sea coral bed using a submersible (PISCES V). Specimens of Antipathes dichotoma were collected at 50 m off Lahaina, Maui. The primary source of carbon to the calcitic C. secundum skeleton is in situ dissolved inorganic carbon (DIC). Using bomb {sup 14}C time markers we calculate radial growth rates of {approx} 170 {micro}m y{sup -1} and ages of 68-75 years on specimens as tall as 28 cm of C. secundum. Gerardia sp., A. dichotoma, and L. glaberrima have proteinaceous skeletons and labile particulate organic carbon (POC) is their primary source of architectural carbon. Using {sup 14}C we calculate a radial growth rate of 15 {micro}m y{sup -1} and an age of 807 {+-} 30 years for a live collected Gerardia sp., showing that these organisms are extremely long lived. Inner and outer {sup 14}C measurements on four sub-fossil Gerardia spp. samples produce similar growth rate estimates (range 14-45 {micro}m y{sup -1}) and ages (range 450-2742 years) as observed for the live collected sample. Similarly, with a growth rate of < 10 {micro}m y{sup -1} and an age of {approx}2377 years, L. glaberrima at the Makapuu coral bed, is also extremely long lived. In contrast, the shallow-collected A. dichotoma samples yield growth rates ranging from 130 to 1,140 {micro}m y{sup -1}. These results show that Hawaiian deep-sea corals grow more slowly and are older than previously thought.

  16. Density, ages, and growth rates in old-growth and young-growth forests in coastal Oregon

    USGS Publications Warehouse

    Tappeiner, J. C.; Huffman, D.; Spies, T.; Bailey, John D.

    1997-01-01

    We studied the ages and diameter growth rates of trees in former Douglas-fir (Pseudotsuga menziesii (Mirb.)Franco) old-growth stands on 10 sites and compared them with young-growth stands (50-70 years old, regenerated after timber harvest) in the Coast Range of western Oregon. The diameters and diameter growth rates for the first 100 years of trees in the old-growth stands were significantly greater than those in the young-growth stands. Growth rates in the old stands were comparable with those from long-term studies of young stands in which density is about 100-120 trees/ha; often young-growth stand density is well over 500 trees/ha. Ages of large trees in the old stands ranged from 100 to 420 years; ages in young stands varied by only about 5 to 10 years. Apparently, regeneration of old-growth stands on these sites occurred over a prolonged period, and trees grew at low density with little self-thinning; in contrast, after timber harvest, young stands may develop with high density of trees with similar ages and considerable self-thinning. The results suggest that thinning may be needed in dense young stands where the management objective is to speed development of old-growth characteristics.

  17. Structural integrity of future aging airplanes

    NASA Technical Reports Server (NTRS)

    Mcguire, Jack F.; Goranson, Ulf G.

    1992-01-01

    A multitude of design considerations is involved in ensuring the structural integrity of Boeing jet transports that have common design concepts validated by extensive analyses, tests, and three decades of service. As airplanes approach their design service objectives, the incidences of fatigue and corrosion may become widespread. Continuing airworthiness of the aging jet fleet requires diligent performance from the manufacturer, the airlines, and airworthiness authorities. Aging fleet support includes timely development of supplemental structural inspection documents applicable to selected older airplanes, teardown inspections of high-time airframes retired from service, fatigue testing of older airframes, and structural surveys of more than 130 airplanes operated throughout the world. Lessons learned from these activities are incorporated in service bulletin recommendations, production line modifications, and design manual updates. An overview of traditional Boeing fleet support activities and the anticipated benefits for future generations of commercial airplanes based on the continuous design improvement process are presented.

  18. Age, growth and size interact with stress to determine life span and mortality

    PubMed Central

    Roach, Deborah Ann

    2012-01-01

    Individuals in a large experimental field population, of the short-lived perennial species Plantago lanceolata, were followed to determine the sources of variation that influence mortality and life span. The design included multiple age groups with initially similar genetic structure, which made it possible to separate age effects from period effects and to identify the genetic component to variation in life span. During a period of stress, individuals of all ages showed parallel increases in mortality but different cohorts experienced this period of high mortality at different ages. This then influenced the distribution of life spans across cohorts. Age and size-age interactions influenced mortality during the period of stress. Smaller individuals died but only if they were old. Additionally, growth and age interacted with stress such that older individuals had negative growth and high mortality whereas younger individuals had positive growth and relatively lower mortality during stress. The results of this study show that it is not simply the environment that can have a major impact on demography in natural populations, rather, age, size and growth can interact with the environment to influence mortality and life span when the environment is stressful. PMID:22664575

  19. The dynamics of bone structure development during pubertal growth.

    PubMed

    Rauch, F

    2012-03-01

    The pubertal growth spurt is a time of rapid changes in bone length, mass and structure, followed by the cessation of longitudinal growth. The two best studied anatomical areas in this respect are the metaphyses and the diaphyses of peripheral long bones. A model is presented here in which the speed of longitudinal growth and the resulting age gradient in metaphyseal bone are key factors in explaining the high incidence of distal radius fractures during puberty. As growth in length accelerates, the age of the bone structural elements at a given distance to the growth plate decreases, leaving less time for cortical thickening through trabecular coalescence. This leads to a discrepancy between stagnant metaphyseal bone strength and increasing mechanical requirements in the case of accidents. In comparison to the metaphysis, diaphyseal bone develops more in line with the increasing mechanical requirements, presumably because the bone formation rates needed for diaphyseal growth in width are only a fraction of the apposition rates in the metaphysis. It remains largely unexplored how local and systemic signals are integrated to achieve site-specific changes in bone structure.

  20. Differential effects of young maternal age on child growth

    PubMed Central

    Yu, Soo Hyun; Mason, John; Crum, Jennifer; Cappa, Claudia; Hotchkiss, David R.

    2016-01-01

    Background The association of early maternal birthing age with smaller children has been widely observed. However, it is unclear if this is due to confounding by factors such as socioeconomic status, or the age at which child growth restriction first occurs. Objective To examine the effect of early maternal birthing age on the first-born child's height-for-age in a sample of developing countries in Africa, Asia, and Latin America. Design Cross-sectional data from Demographic Health Surveys from 18 countries were used, to select the first-born child of mothers aged 15–24 years and a range of potential confounding factors, including maternal height. Child length/height-for-age z-scores (HAZs) was estimated in age bands of 0–11, 12–23, 24–35, 36–47, and 48–59 months; HAZ was first compared between maternal age groups of 15–17, 18–19, and 20–24 years. Results 1) There were significant bivariate associations between low child HAZ and young maternal age (71 of 180 possible cases; at p<0.10), but the majority of these did not persist when controlling for confounders (41 cases, 23% of the 180). 2) For children <12 months, when controlling for confounders, three out of seven Asian countries showed a significant association between lower infant HAZ and low maternal age, as did six out of nine African countries (15–17 or 15–19 years vs. the older group). 3) The association (adjusted) continued after 24 months in 12 of the 18 countries, in Africa, Asia, and Latin America. 4) The stunting differences for children between maternal age groups were around 9 percentage points (ppts) in Asia, 14 ppts in Africa, and 10 ppts in Latin America. These data do not show whether this is due to, for example, socioeconomic factors that were not included, an emerging effect of intrauterine growth restriction, or the child feeding or caring behaviors of young mothers. The latter is considered to be the most likely. Conclusions The effect of low maternal age on child height

  1. Differential effects of young maternal age on child growth.

    PubMed

    Yu, Soo Hyun; Mason, John; Crum, Jennifer; Cappa, Claudia; Hotchkiss, David R

    2016-01-01

    Background The association of early maternal birthing age with smaller children has been widely observed. However, it is unclear if this is due to confounding by factors such as socioeconomic status, or the age at which child growth restriction first occurs. Objective To examine the effect of early maternal birthing age on the first-born child's height-for-age in a sample of developing countries in Africa, Asia, and Latin America. Design Cross-sectional data from Demographic Health Surveys from 18 countries were used, to select the first-born child of mothers aged 15-24 years and a range of potential confounding factors, including maternal height. Child length/height-for-age z-scores (HAZs) was estimated in age bands of 0-11, 12-23, 24-35, 36-47, and 48-59 months; HAZ was first compared between maternal age groups of 15-17, 18-19, and 20-24 years. Results 1) There were significant bivariate associations between low child HAZ and young maternal age (71 of 180 possible cases; at p<0.10), but the majority of these did not persist when controlling for confounders (41 cases, 23% of the 180). 2) For children <12 months, when controlling for confounders, three out of seven Asian countries showed a significant association between lower infant HAZ and low maternal age, as did six out of nine African countries (15-17 or 15-19 years vs. the older group). 3) The association (adjusted) continued after 24 months in 12 of the 18 countries, in Africa, Asia, and Latin America. 4) The stunting differences for children between maternal age groups were around 9 percentage points (ppts) in Asia, 14 ppts in Africa, and 10 ppts in Latin America. These data do not show whether this is due to, for example, socioeconomic factors that were not included, an emerging effect of intrauterine growth restriction, or the child feeding or caring behaviors of young mothers. The latter is considered to be the most likely. Conclusions The effect of low maternal age on child height restriction from 0 to

  2. Growth characteristics and otolith analysis on age-0 American shad

    USGS Publications Warehouse

    Sauter, Sally T.; Wetzel, Lisa A.

    2011-01-01

    Otolith microstructure analysis provides useful information on the growth history of fish (Campana and Jones 1992, Bang and Gronkjaer 2005). Microstructure analysis can be used to construct the size-at-age growth trajectory of fish, determine daily growth rates, and estimate hatch date and other ecologically important life history events (Campana and Jones 1992, Tonkin et al. 2008). This kind of information can be incorporated into bioenergetics modeling, providing necessary data for estimating prey consumption, and guiding the development of empirically-based modeling scenarios for hypothesis testing. For example, age-0 American shad co-occur with emigrating juvenile fall Chinook salmon originating from Hanford Reach and the Snake River in the lower Columbia River reservoirs during the summer and early fall. The diet of age-0 American shad appears to overlap with that of juvenile fall Chinook salmon (Chapter 1, this reoprt), but juvenile fall Chinook salmon are also known to feed on age-0 American shad in the reservoirs (USGS unpublished data). Abundant, energy-dense age-0 American shad may provide juvenile fall Chinook salmon opportunities for rapid growth during the time period when large number of age-0 American shad are available. Otolith analysis of hatch dates and the growth curve of age-0 American shad could be used to identify when eggs, larvae, and juveniles of specific size classes are temporally available as food for fall Chinook salmon in the lower Columbia River reservoirs. This kind of temporally and spatially explicit life history information is important to include in bioenergetics modeling scenarios. Quantitive estimates of prey consumption could be used with spatially-explicit estimates of prey abundance to construct a quantitative assessment of the age-0 American shad impact on a reservoir food web.


    Analysis of the age-0 American shad growth trajectory or individual growth records may show evidence of differential growth rates over

  3. Birth weight, postnatal growth, and age at menarche.

    PubMed

    Terry, Mary Beth; Ferris, Jennifer S; Tehranifar, Parisa; Wei, Ying; Flom, Julie D

    2009-07-01

    Larger body size in childhood is correlated with earlier age at menarche; whether birth and infant body size changes are also associated with age at menarche is less clear. The authors contacted female participants enrolled in the New York site of the US National Collaborative Perinatal Project born between 1959 and 1963 (n = 262). This racially and ethnically diverse cohort (38% white, 40% African American, and 22% Puerto Rican) was used to investigate whether maternal (body size, pregnancy weight gain, age at menarche, smoking) and birth (birth weight, birth length, placental weight) variables and early infant body size changes were associated with age at menarche even after considering later childhood body size. Higher percentile change in weight from ages 4 months to 1 year was associated with earlier age at menarche even after adjustment for later childhood growth (beta = -0.15, 95% confidence interval: -0.27, -0.02 years per 10-percentile change in weight from ages 4 months to 1 year). The association was in the same direction for all 3 racial/ethnic groups but was largest for the white group. These New York Women's Birth Cohort Adult Follow-up data (2001-2006) suggest that infant weight gain, in addition to childhood weight gain, may be associated with earlier age at menarche.

  4. Body growth considerations in age-specific dosimetry. Final report

    SciTech Connect

    Eckerman, K.F.

    1993-09-30

    This report describes the manner in which the age-specific dosimetric calculations of the International Commission on Radiological Protection (ICRP) addressed changes in organ size that occur with age. The approach involves an interpolation of dosimetric information derived for six reference individuals using the inverse of the total body mass as the interpolation variable. An alternative formulation is investigated that employs a functional representation of the organ mass as a function of age in conjunction with an explicit formulation of the dosimetric factors in terms of organ mass. Using an exponential-logistic growth function as suggested by Walker, this report demonstrates, through application to the dosimetry of radioiodines in the thyroid, that the alternative formulation can be formulated and implemented. Although either approach provides a workable basis for age-specific dosimetry, it is clear that the functional representation of organ growth has some attractive features. However, without question, the major difficulty is the quality and quantity of data available to address the age- and gender-specific parameters in the dosimetric formulations.

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

    USGS Publications Warehouse

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

    2009-01-01

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

  6. Spaceflight and age affect tibial epiphyseal growth plate histomorphometry

    NASA Technical Reports Server (NTRS)

    Montufar-Solis, Dina; Duke, Pauline J.; Durnova, G.

    1992-01-01

    Growth plate histomorphometry of rats flown aboard the Soviet biosatellite Cosmos 2044, a 14-day spaceflight, was compared with that of control groups. In growth plates of flight animals, there was a significant increase in cell number per column and height of the proliferative zone and a reduction in height and cell number in the hypertrophy/calcification zone. No significant differences were found in matrix organization at the ultrastructural level of flight animals, indicating that although spacefligfht continues to affect bone growth of 15-wk-old rats, extracellular matrix is not altered in the same manner as seen previously in younger animals. All groups showed growth plate characteristics attributed to aging: lack of calcification zone, reduced hypertrophy zone, and unraveling of collagen fibrils. Tail-suspended controls did not differ from other controls in any of the parameters measured. The results suggest that growth plates of older rats are less responsive to unloading by spaceflight or suspension than those of younger rats and provide new evidence about the modifying effect of spaceflight on the growth plate.

  7. 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.

  8. Age and growth of the whitefish in Lake Superior

    USGS Publications Warehouse

    Dryer, William R.

    1963-01-01

    The average annual commercial production of whitefish in the U.S. waters of Lake Superior dropped from 2,194,000 pounds in 1879-1908 to 504,000 pounds in 1911-59. The modern production, though far below the earlier, has accounted for more than 10 percent of the total value of the fishery in all but one of the last 20 years. Data are given on growth rate, age and year-class composition, size distribution, and length-weight relation of 1,800 fish collected in 1957-59 at Bayfield, Wis., and Marquette, Whitefish Point, and Dollar Settlement, Mich. Studies of the body-scale relation, sex ratio, and age and size at maturity were limited to fish collected at Bayfield. The age composition and mean age varied widely by port and year of capture. Oldest fish were those of the 1957 Bayfield samples which were dominated by age group VII and averaged 5.5 years old. The youngest were from Whitefish Point in 1959; age-group III was dominant, and the mean age was 3.2 years. The evidence on the strength of year classes was not clear-cut, but it was obvious that fluctuations in stocks of different areas were largely independent. The percentage of legal-size fish (17 inches or longer) in age groups ranged widely; only 8.6 percent of the V group were legal in the 1957 Bayfield collections, whereas 100 percent of fish of the same age were legal in the 1957-59 collections from Whitefish Point. The weight of whitefish in the combined samples increased as the 3.2408 power of the length. The growth rate from the fastest to the slowest growing stocks ranked as follows: Whitefish Point; Dollar Settlement and Marquette (fish from the two ports reversed ranks after 3 years); Bayfield. The major differences in growth in length among the various stocks occurred during the first years of life. Beyond the fifth year the annual increments were nearly the same in all stocks. The whitefish from Whitefish Point, Dollar Settlement, and Marquette are among the fastest growing in the Great Lakes. The

  9. Effects of growth hormone and insulin-like growth factor 1 deficiency on ageing and longevity.

    PubMed

    Laron, Zvi

    2002-01-01

    Present knowledge on the effects of growth hormone (GH)/insulin-like growth hormone (IGF)1 deficiency on ageing and lifespan are reviewed. Evidence is presented that isolated GH deficiency (IGHD), multiple pituitary hormone deficiencies (MPHD) including GH, as well as primary IGE1 deficiency (GH resistance, Laron syndrome) present signs of early ageing such as thin and wrinkled skin, obesity, hyperglycemia and osteoporosis. These changes do not seem to affect the lifespan, as patients reach old age. Animal models of genetic MPHD (Ames and Snell mice) and GH receptor knockout mice (primary IGF1 deficiency) also have a statistically significant higher longevity compared to normal controls. On the contrary, mice transgenic for GH and acromegalic patients secreting large amounts of GH have premature death. In conclusion longstanding GH/IGF1 deficiency affects several parameters of the ageing process without impairing lifespan, and as shown in animal models prolongs longevity. In contrast high GH/IGF1 levels accelerate death.

  10. AGE-STRUCTURAL TRANSITION IN INDONESIA

    PubMed Central

    Kreager, Philip; Schröder-Butterfill, Elisabeth

    2016-01-01

    This paper responds to recent calls for empirical study of the impact of age-structural transition. It begins by reviewing evidence of cohort oscillations in twentieth-century Indonesia, which indicates that current older generations are likely to have smaller numbers of children on whom they may rely than generations before and after them. However, to assess whether the imbalances implied by this situation are actually influencing people’s lives, attention to further factors shaping the availability and reliability of younger generations, notably differences in socio-economic status and in patterns of inter-generational support flows, is required. Community-level Indonesian data confirm that elders in the lower social strata are child-poor. Social structural and family network patterns, however, have a greater influence on the availability of inter-generational support than cohort differentials. PMID:27158254

  11. The old age security hypothesis and optimal population growth.

    PubMed

    Bental, B

    1989-03-01

    The application of the Samuelson-Diamond overlapping generations framework to the old age security hypothesis indicates that government intervention schemes can influence the relationship between population growth and capital accumulation. The most direct means of optimizing population growth is through taxes or subsidies that relate to the intergenerational transfer of wealth. A pay-as-you-go social security scheme, in which payment is predicated on the number of children the receiver has and is financed by taxes levied on the working population, emerges as the most likely intervention to produce the optimal steady state equilibrium. This system is able to correct any distortions the private sector may build into it. In contrast, a child support system, in which the government subsidizes or taxes workers according to their family size, can guarantee the optimal capital:labor ratio but not the optimal population growth rate. Thus, if the government seeks to decrease the population growth rate, the appropriate intervention is to levy a lump-sum social-security tax on workers and transfer the revenues to the old; the direction should be reversed if the goal is to increase population growth. Another alternative, a lump sum social security system, can guarantee optimal population growth but not a desirable capital:labor ratio. Finally, the introduction of money as a valued commodity into an economy with a high capital:labor ratio will also serve to decrease the population growth rate and solve the intergenerational transfer problem through the private sector without any need for government intervention.

  12. Natural selection and age-structured populations.

    PubMed

    Demetrius, L

    1975-03-01

    This paper studies the properties of a new class of demographic parameters for age-structured populations and analyzes the effect of natural selection on these parameters. Two new demographic variables are introduced: the entropy of a population and the reproductive potential. The entropy of a population measures the variability of the contribution of the different age classes to the stationary population. The reproductive potential measures the mean of the contribution of the different age classes to the Malthusian parameter. The Malthusian parameter is precisely the difference between the entropy and the reproductive potential. The effect of these demographic variables on changes in gene frequency is discussed. The concept of entropy of a genotype is introduced and it is shown that in a random mating population in Hardy-Weinberg equilibrium and under slow selection, the rate of change of entropy is equal to the genetic variance in entropy minus the covariance in entropy and reproductive potential. This result is an information theoretic analog of Fisher's fundamental theorem of natural selection.

  13. Age structure and cooperation in coevolutionary games on dynamic network

    NASA Astrophysics Data System (ADS)

    Qin, Zilong; Hu, Zhenhua; Zhou, Xiaoping; Yi, Jingzhang

    2015-04-01

    Our proposed model imitates the growth of a population and describes the age structure and the level of cooperation in games on dynamic network with continuous changes of structure and topology. The removal of nodes and links caused by age-dependent attack, together with the nodes addition standing for the newborns of population, badly ruins Matthew effect in this coevolutionary process. Though the network is generated by growth and preferential attachment, it degenerates into random network and it is no longer heterogeneous. When the removal of nodes and links is equal to the addition of nodes and links, the size of dynamic network is maintained in steady-state, so is the low level of cooperation. Severe structure variation, homogeneous topology and continuous invasion of new defection jointly make dynamic network unsuitable for the survival of cooperator even when the probability with which the newborn players initially adopt the strategy cooperation is high, while things change slightly when the connections of newborn players are restricted. Fortunately, moderate interactions in a generation trigger an optimal recovering process to encourage cooperation. The model developed in this paper outlines an explanation of the cohesion changes in the development process of an organization. Some suggestions for cooperative behavior improvement are given in the end.

  14. [Analysis on age structure and dynamics of Kindonia uniflora populations].

    PubMed

    Zhang, Wenhui; Li, Jingxia; Li, Hong; Liu, Xiangjun

    2004-04-01

    Kindonia uniflora is a perennial clone herbaceous plant, and also, a native endangered plant in China. This paper studied its age structure, life table and survivorship curve in different habitats in Taibai mountain area. The results indicated that the age structure and dynamics of K. uniflora populations in the Betula utilis forest at altitude 2500-2700 m, in the Abies fargesii forest at altitude 2700-2900 m, and in the Larix chinensis forest at altitude 2900-3100 m had the similar pattern and developing tendency. The number of younger ramets at 1-2 years old or older than 5 years was less, and the number of ramets at 3-5 years old was the highest in the age structures. The negative values of dx (dead number), qx (mortality rate) and Kx (Killing rate) in the life table showed the increasing rate of the population sizes during the age stage. The survivorship curve of K. uniflora populations in different habitats belonged to Deevey C after 3-5 years old. The mortality rate of populations during 5-10 years stage was higher, and was stable after 10 years old. As for the characters of asexual propagation and clone growth, the rhizomes of the populations were in humus of soil, and developed and expanded as guerilla line style. During growth season, only one leaf grew above ground at every inter-node, and the population growth and development were rarely influenced by external factors. The forest communities, such as Betula utilis, Abies fargesii and Larix chinensis forest, in which K. uniflora populations lived, were at middle or higher mountain, where there were rarely disturbance from human being. Therefore, the habitats for K. uniflora populations to live were relatively stable. As the altitude increased, the disturbances from human being became less, the density of K. uniflora populations increased, the life cycle expanded, the peak of population death delayed, and the population living strategy changed to adapt to the habitats. K. uniflora populations preferred to

  15. Fractional Dynamics of Network Growth Constrained by Aging Node Interactions

    PubMed Central

    Safdari, Hadiseh; Zare Kamali, Milad; Shirazi, Amirhossein; Khalighi, Moein; Jafari, Gholamreza; Ausloos, Marcel

    2016-01-01

    In many social complex systems, in which agents are linked by non-linear interactions, the history of events strongly influences the whole network dynamics. However, a class of “commonly accepted beliefs” seems rarely studied. In this paper, we examine how the growth process of a (social) network is influenced by past circumstances. In order to tackle this cause, we simply modify the well known preferential attachment mechanism by imposing a time dependent kernel function in the network evolution equation. This approach leads to a fractional order Barabási-Albert (BA) differential equation, generalizing the BA model. Our results show that, with passing time, an aging process is observed for the network dynamics. The aging process leads to a decay for the node degree values, thereby creating an opposing process to the preferential attachment mechanism. On one hand, based on the preferential attachment mechanism, nodes with a high degree are more likely to absorb links; but, on the other hand, a node’s age has a reduced chance for new connections. This competitive scenario allows an increased chance for younger members to become a hub. Simulations of such a network growth with aging constraint confirm the results found from solving the fractional BA equation. We also report, as an exemplary application, an investigation of the collaboration network between Hollywood movie actors. It is undubiously shown that a decay in the dynamics of their collaboration rate is found, even including a sex difference. Such findings suggest a widely universal application of the so generalized BA model. PMID:27171424

  16. Structural manifestations of aging in Se-rich glasses

    NASA Astrophysics Data System (ADS)

    Dash, S.; Ravindren, S.; Chen, P.; Boolchand, P.

    2015-03-01

    We examine weakly cross-linked GexSe100-x (0%aging at RT for 4 months, we find the width of the glass transition W(x) steadily decreasing from 10C at 7% Ge to 2C for pure Se. The 5-fold reduction of W(x) with a decrease of Ge content is accompanied by a 2-fold increase in the non-reversing enthalpy. Rejuvenation of the aged glasses changes W(x) from 15C at 7% Ge to 7C for pure Se. Tg is found to decrease upon rejuvenation with the difference (Tg(aged)-Tg(rejuv)) showing a maximum near 3% Ge and vanishing for pure Se and 6% of Ge, which are topological thresholds. These results in Se-rich glasses are consistent with aging induced decoupling of Se8 crowns and growth of extended range structural correlations between polymeric Sen chains due to lone pair interactions. At higher x, near 8-10% of Ge, eutectic effects are manifested. Work supported by NSF Grant DMR 08-53957.

  17. "The Wisdom of Age": Perspectives on Aging and Growth among Lesbian Older Adults.

    PubMed

    Putney, Jennifer M; Leafmeeker, Rebecca R; Hebert, Nicholas

    2016-04-01

    Older lesbian-identified women are a health disparate yet resilient population about whom knowledge is limited and emerging. Among the areas in need of research are older lesbians' experiences of later life and stress-related growth. This article presents the findings from a qualitative study that investigated older lesbians' experiences of adversity and adaptation as they age. In-depth, exploratory interviews were conducted with 12 lesbian-identified women who were between the ages of 65-80. This study applied grounded theory methodology to identify respondents sources of stress and fear, their strengths and coping strategies and how those relate to each other and to their growth in later life. We advance a model of adaptive change that shows how spirituality, social support, and resistance to cultural norms help older lesbian adults cope with loss, illness, and discrimination and develop wisdom in later life. Knowledgeable practitioners can help older lesbian women identify and maintain sources of social support, explore spirituality, and facilitate continuous growth through the end of life. Social workers can advocate for services that are welcoming and affirmative so as to reduce fears of isolation and dependence associated with health decline.

  18. Growth of short children born small for gestational age and their response to growth hormone therapy.

    PubMed

    Prasad, Hemchand Krishna; Khadilkar, Vaman V; Chiplonkar, Shashi A; Khadilkar, Anuradha V

    2013-05-08

    Growth hormone [GH] is licensed for use in children born small for gestational age (SGA) who fail to catch-up. We retrospectively compared the response of twenty children born SGA (who satisfied the auxological criteria) to growth hormone (Group I) versus randomly selected age and sex matched controls from a group of SGA children with growth related complaints, not treated with GH (Group II). After 2 years of GH therapy the HAZ increased from -2.8 to -1.6 in Group I, compared 2.2 to -1.7 in group II (P-value < 0.05). The percentage of pubertal children rose from 55% to 65% in cases versus 60% to 75% in the controls (P>0.05). GH resulted in increase in growth velocity Z-score during the first year and (4.3±0.5 in Group-I versus - 0.5±0.6 in Group-II, P<0.05) second year of treatment (1.7±0.4 in cases versus -0.6±0.7 in controls, P<0.05).Thus, GH improves height of short SGA children without accelerating pubertal progression.

  19. Growth and Structural Properties of Lead

    NASA Astrophysics Data System (ADS)

    Fang, Kai

    Using the high-resolution low-energy electron diffraction (HRLEED) technique, we have studied the structures of thin Pb films during the Molecular Beam Epitaxy (MBE). In an effort to find out the characteristics of a non-equilibrium growth process, we have investigated the homoepitaxy of Pb on a Pb(110) substrate using a high deposition rate. In comparison, we have also examined in detail the heteroepitaxy of Pb using W(112) as a substrate, in which we have obtained information about the interface formation and its kinetics property. As a precursor to understand the structures observed during growth, we have performed a detailed study on Pb itself, using Pb(110) as a sample, with or without impurities. During the non-equilibrium growth of Pb on Pb(110), we have observed the kinetic roughening phenomena in the form of non-conventional dynamic scaling and faceting. At the initial stage of growth, the interface width w changes with deposition time t in a scaling form w ~ t^beta with beta = 0.77 +/- 0.05. The other scaling hypothesis involving lateral correlation length xi ~ t ^{beta/alpha} is not valid and the local roughness increases dramatically. However, the short-range height-height correlation function H(r) still scales with r in the form of H(r) ~ f(t)r^{2alpha} with alpha = 1.33 +/- 0.05.. During the growth of Pb on W(112), we have observed rotational disorder. Pb grows on W(112) in a typical 3 -D fashion, forming Pb(111) islands. While the surface normal of the Pb(111) islands aligns with that of the W(112), the lateral lattice orientation within the Pb(111) plane is not unique with respect to the W(112) substrate. Depending on the growth rate, the Pb overlayer may have different morphologies in terms of number of different island orientations. The structure of a clean Pb(110) surface goes through a series of phase transitions between room temperature and the bulk melting temperature (600.7 K), such as ordered flat phase (OF), disordered flat (DOF) phase

  20. Age class, longevity and growth rate relationships: protracted growth increases in old trees in the eastern United States.

    PubMed

    Johnson, Sarah E; Abrams, Marc D

    2009-11-01

    This study uses data from the International Tree-Ring Data Bank website and tree cores collected in the field to explore growth rate (basal area increment, BAI) relationships across age classes (from young to old) for eight tree species in the eastern US. These species represent a variety of ecological traits and include those in the genera Populus, Quercus, Pinus, Tsuga and Nyssa. We found that most trees in all age classes and species exhibit an increasing BAI throughout their lives. This is particularly unusual for trees in the older age classes that we expected to have declining growth in the later years, as predicted by physiological growth models. There exists an inverse relationship between growth rate and increasing age class. The oldest trees within each species have consistently slow growth throughout their lives, implying an inverse relationship between growth rate and longevity. Younger trees (< 60 years of age) within each species are consistently growing faster than the older trees when they are of the same age resulting from a higher proportion of fast-growing trees in these young age classes. Slow, but increasing, BAI in the oldest trees in recent decades is a continuation of their growth pattern established in previous centuries. The fact that they have not shown a decreasing growth rate in their old age contradicts physiological growth models and may be related to the stimulatory effects of global change phenomenon (climate and land-use history).

  1. Normative and Structural Perspectives on Age in a Work Organization.

    ERIC Educational Resources Information Center

    Lawrence, Barbara S.

    Age grading, the differentiation of social groups by members' age judgments, is widely regarded to be a universal aspect of social life. Most studies have examined age structurally (demographically), rather than normatively (modally). This study presents survey data measuring employees' age judgments of managerial careers collected from an…

  2. Preliminary age, growth and maturity estimates of spotted ratfish (Hydrolagus colliei) in British Columbia

    NASA Astrophysics Data System (ADS)

    King, J. R.; McPhie, R. P.

    2015-05-01

    The spotted ratfish (Hydrolagus colliei) is a chimaeroid ranging from southeast Alaska to Baja California and found at depths of up to 1029 m. Despite being widespread and ubiquitous, few biological parameter estimates exist for spotted ratfish due to a lack of suitable ageing structures to estimate age and growth. We present preliminary results of age, growth and maturity estimates based on a new method in which tritor ridges are counted on the vomerine tooth plate. We also provide a method for estimating the number of worn tritor ridges based on tooth plate diameter measurements for the spotted ratfish. The tritor ridges are distinct bumps that are easy to identify and precision estimates between readers suggests that this method is transferable. Tritor ridges are a potential structure for estimating age in H. colliei and we provide recommendations for future research to improve the method. We sampled 269 spotted ratfish captured in trawl surveys off the coast British Columbia ranging in size from 74 to 495 mm in precaudal length (PCL). The estimated ages ranged from 2 to 16 years for males and from 2 to 21 years for females. The von Bertalanffy, von Bertalanffy with known size at birth, Gompertz and logistic growth models were fitted to the data. Based on Akaike information criterion corrected for sample size and number of parameters estimated, the logistic growth curve was selected as most suitable. The logistic growth model yielded the following parameter estimates: Linf=407.22 mm (PCL), k=0.23 year-1, t0=-7.06 years for males; L∞=494.52 mm (PCL), k=0.26 year-1, t0=-8.35 years for females. Estimated ages at 50% maturity were 12 and 14 years for males and females, respectively. Correspondingly, the size at 50% maturity estimates was smaller for males (302 mm, PCL) than females (393 mm, PCL). Both estimates are larger than those made for spotted ratfish off of California indicating regional differences in life history traits for this species. Our preliminary

  3. Changes in age composition and growth characteristics of Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) over 400 years.

    PubMed

    Balazik, Matthew T; Garman, Greg C; Fine, Michael L; Hager, Christian H; McIninch, Stephen P

    2010-10-23

    Populations of sturgeon (Acipenseridae) have experienced global declines, and in some cases extirpation, during the past century. In the current era of climate change and over-harvesting of fishery resources, climate models, based on uncertain boundary conditions, are being used to predict future effects on the Earth's biota. A collection of approximately 400-year-old Atlantic sturgeon spines from a midden in colonial Jamestown, VA, USA, allowed us to compare the age structure and growth rate for a pre-industrial population during a 'mini-ice age' with samples collected from the modern population in the same reach of the James River. Compared with modern fish, the colonial population was characterized by larger and older individuals and exhibited significantly slower growth rates, which were comparable with modern populations at higher latitudes of North America. These results may relate to higher population densities and/or colder water temperatures during colonial times.

  4. Evolving tip structures can explain age-dependent microtubule catastrophe.

    PubMed

    Coombes, Courtney E; Yamamoto, Ami; Kenzie, Madeline R; Odde, David J; Gardner, Melissa K

    2013-07-22

    Microtubules are key structural and transport elements in cells. The dynamics at microtubule ends are characterized by periods of slow growth, followed by stochastic switching events termed "catastrophes," in which microtubules suddenly undergo rapid shortening. Growing microtubules are thought to be protected from catastrophe by a GTP-tubulin "cap": GTP-tubulin subunits add to the tips of growing microtubules but are subsequently hydrolyzed to GDP-tubulin subunits once they are incorporated into the microtubule lattice. Loss of the GTP-tubulin cap exposes GDP-tubulin subunits at the microtubule tip, resulting in a catastrophe event. However, the mechanistic basis for sudden loss of the GTP cap, leading to catastrophe, is not known. To investigate microtubule catastrophe events, we performed 3D mechanochemical simulations that account for interactions between neighboring protofilaments. We found that there are two separate factors that contribute to catastrophe events in the 3D simulation: the GTP-tubulin cap size, which settles into a steady-state value that depends on the free tubulin concentration during microtubule growth, and the structure of the microtubule tip. Importantly, 3D simulations predict, and both fluorescence and electron microscopy experiments confirm, that microtubule tips become more tapered as the microtubule grows. This effect destabilizes the tip and ultimately contributes to microtubule catastrophe. Thus, the likelihood of a catastrophe event may be intimately linked to the aging physical structure of the growing microtubule tip. These results have important consequences for catastrophe regulation in cells, as microtubule-associated proteins could promote catastrophe events in part by modifying microtubule tip structures.

  5. Ages and Growth of the Continental Crust from Radiogenic Isotopes

    NASA Astrophysics Data System (ADS)

    Patchett, P. J.; Samson, S. D.

    2003-12-01

    The development and application of radiogenic isotopes to dating of geologic events, and to questions of growth, evolution, and recycling processes in the continental crust are mature areas of scientific inquiry. By this we understand that many of the approaches used to date rocks and constrain the evolution of the continents are well established, even routine, and that the scope of data available on age and evolution of continents is very large. This is not to say that new approaches have not been developed in recent years, or that new approaches and/or insights cannot be developed in the future. However, the science of continental crustal evolution is definitely a domain where many of the problems are well defined, the power of the techniques used to solve them are well known, and the limitations of field and laboratory databases, as well as the preserved geologic record, are understood.From the very early days of crustal evolution studies, it was innovations and improvements in laboratory techniques that drove the pace of discovery (e.g., Holmes, 1911; Nier, 1939). This remained true through all the increments in capability reviewed in this chapter, up to the present day. Thus, continental crustal evolution is an area of Earth science where a species of very laboratory-oriented investigator, the "radiogenic isotope geologist" or "geochronologist," has made major advances, even breakthroughs, in understanding. This is true in spite of the fact that many of the individuals of the species may have lacked field expertise, or even more than a primitive level of geologic background. Because design and building of instruments like radiation detectors or mass spectrometers requires a knowledge of physics, many of the early practitioners of rock dating were physicists, like Alfred Nier (cited above). Since the 1970s, essentially all mass spectrometers have been constructed by specialized commercial firms, and the level of physics expertise among isotope geologists has

  6. Insulin-Like Growth Factor 1: At the Crossroads of Brain Development and Aging

    PubMed Central

    Wrigley, Sarah; Arafa, Donia; Tropea, Daniela

    2017-01-01

    Insulin-like growth factor 1 (IGF1) is a polypeptide hormone structurally similar to insulin. It is central to the somatotropic axis, acting downstream of growth hormone (GH). It activates both the mitogen-activated protein (MAP) kinase and PI3K signaling pathways, acting in almost every tissue in the body to promote tissue growth and maturation through upregulation of anabolic processes. Overall GH and IGF1 signaling falls with age, suggesting that it is this reduced IGF1 activity that leads to age-related changes in organisms. However, mutations that reduce IGF1-signaling activity can dramatically extend the lifespan of organisms. Therefore, the role of IGF1 in the overall aging process is unclear. This review article will focus on the role of IGF1 in brain development and aging. The evidence points towards a role for IGF1 in neurodevelopment both prenatally and in the early post-natal period, and in plasticity and remodeling throughout life. This review article will then discuss the hallmarks of aging and cognitive decline associated with falls in IGF1 levels towards the end of life. Finally, the role of IGF1 will be discussed within the context of both neuropsychiatric disorders caused by impaired development of the nervous system, and neurodegenerative disorders associated with aging. IGF1 and its derivatives are shown to improve the symptoms of certain neuropsychiatric disorders caused by deranged neurodevelopment and these effects have been correlated with changes in the underlying biology in both in vitro and in vivo studies. On the other hand, studies looking at IGF1 in neurodegenerative diseases have been conflicting, supporting both a role for increased and decreased IGF1 signaling in the underlying pathogenesis of these diseases. PMID:28203146

  7. Insulin-Like Growth Factor 1: At the Crossroads of Brain Development and Aging.

    PubMed

    Wrigley, Sarah; Arafa, Donia; Tropea, Daniela

    2017-01-01

    Insulin-like growth factor 1 (IGF1) is a polypeptide hormone structurally similar to insulin. It is central to the somatotropic axis, acting downstream of growth hormone (GH). It activates both the mitogen-activated protein (MAP) kinase and PI3K signaling pathways, acting in almost every tissue in the body to promote tissue growth and maturation through upregulation of anabolic processes. Overall GH and IGF1 signaling falls with age, suggesting that it is this reduced IGF1 activity that leads to age-related changes in organisms. However, mutations that reduce IGF1-signaling activity can dramatically extend the lifespan of organisms. Therefore, the role of IGF1 in the overall aging process is unclear. This review article will focus on the role of IGF1 in brain development and aging. The evidence points towards a role for IGF1 in neurodevelopment both prenatally and in the early post-natal period, and in plasticity and remodeling throughout life. This review article will then discuss the hallmarks of aging and cognitive decline associated with falls in IGF1 levels towards the end of life. Finally, the role of IGF1 will be discussed within the context of both neuropsychiatric disorders caused by impaired development of the nervous system, and neurodegenerative disorders associated with aging. IGF1 and its derivatives are shown to improve the symptoms of certain neuropsychiatric disorders caused by deranged neurodevelopment and these effects have been correlated with changes in the underlying biology in both in vitro and in vivo studies. On the other hand, studies looking at IGF1 in neurodegenerative diseases have been conflicting, supporting both a role for increased and decreased IGF1 signaling in the underlying pathogenesis of these diseases.

  8. Precision of age estimates from different ageing structures in selected freshwater teleosts.

    PubMed

    Khan, Shahista; Khan, M Afzal; Miyan, Kaish; Lone, Faisal Ahmad

    2015-03-01

    The present study was undertaken with a view to compare the precision of age readings obtained from different ageing structures of some important freshwater teleosts viz., Hypophthalmichthys molitrix, Mastacembelus armatus and Ompok pabda. Standard procedures were followed to study the ageing structures. Based on the highest percent agreement and lowest average percentage of error and coefficient of variation values, precise age estimates were exhibited by opercular bones in H. molitrix and vertebrae in the remaining two fish, M. armatus and O. pabda. When precise age estimates were compared among the age estimates of other ageing structures, highest percent agreement and lowest average percent error and coefficient of variation values were exhibited by vertebrae (versus opercular bones) in H. molitrix and opercular bones (versus vertebrae) in both M. armatus and O. pabda. When mean age estimates from different ageing structures were compared, vertebrae and opercular bones exhibited comparable values in H. molitrix. In M. armatus, mean values of precise age estimates from vertebrae were significantly different from the values of other ageing structures. However, in O. pabda, vertebrae as well as opercular bones showed insignificantly different age readings.

  9. Linear growth of structure in massive bigravity

    SciTech Connect

    Solomon, Adam R.; Akrami, Yashar; Koivisto, Tomi S. E-mail: yashar.akrami@astro.uio.no

    2014-10-01

    The ghost-free theory of massive gravity with two dynamical metrics has been shown to produce viable cosmological expansion, where the late-time acceleration of the Universe is due to the finite range of the gravitational interaction rather than a nonzero cosmological constant. Here the cosmological perturbations are studied in this theory. The full perturbation equations are presented in a general gauge and analyzed, focusing on subhorizon scales in the quasistatic limit during the matter-dominated era. An evolution equation for the matter inhomogeneities and the parameters quantifying the deviations from general relativistic structure formation are expressed in terms of five functions whose forms are determined directly by the coupling parameters in the theory. The evolution equation has a similar structure to Horndeski-type scalar-tensor theories, exhibiting a modified growth rate and scale-dependence at intermediate wavenumbers. Predictions of the theory are confronted with observational data on both background expansion and large-scale structure, although care must be taken to ensure a model is stable. It is found that while the stable models fit the data well, they feature deviations from the standard cosmology that could be detected or ruled out by near-future experiments.

  10. Age and growth of the mutton hamlet Alphestes afer, with a review of the size and age of sex change among epinephelids.

    PubMed

    Marques, S; Ferreira, B P

    2016-07-01

    This paper presents results on the age, growth and population structure of a small grouper, the mutton hamlet Alphestes afer, and discusses the observed size and age structure patterns in relation to reproductive strategies among the epinephelids. Ages were determined by examination of sectioned otoliths, which showed a distinct pattern of alternating translucent and opaque zones that formed annually, as validated with tetracycline labelling. The von Bertalanffy growth function was adjusted to the length-at-age data of the males and females, but no significant differences were observed between the resulting parameters. The females, however, were older at given sizes and attained larger sizes and ages, with a maximum observed longevity of 13 years and a total length (LT ) of 26 cm, while the males attained maximum longevities of only 10 years and a 22 cm maximum LT . The LT and age range for the sex change was 16-25 cm and 3-11 years. The total mortality rate (Z) was estimated to be 0·55 for females and 0·82 for males. With the males younger and smaller than the females, this species differed from the pattern commonly observed for protogynous epinephelids. Males had slower growth after maturation, probably due to energy allocation to sperm production during sexual development. This study shows that demography is an important tool to understand the pathways for reproductive strategies in grouper populations.

  11. Muscle growth in young horses: Effects of age, cytokines, and growth factors.

    PubMed

    LaVigne, E K; Jones, A K; Londoño, A Sanchez; Schauer, A S; Patterson, D F; Nadeau, J A; Reed, S A

    2015-12-01

    Success as equine athletes requires proper muscle growth in young horses. Muscle hypertrophy occurs through protein synthesis and the contribution of muscle satellite cells, which can be stimulated or inhibited by cytokines and growth factors present during exercise and growth. The hypotheses of this study were that 1) the LM area in young horses would increase over 1 yr, and 2) specific cytokines and growth factors (IL-1β, IL-6, tumor necrosis factor [TNF]-α, IGF-I, and fibroblast growth factor [FGF]-2) would alter proliferation and differentiation of satellite cells isolated from young horses. Fourteen horses were divided into 3 age groups: weanlings ( = 5), yearlings to 2 yr olds ( = 4), and 3 to 4 yr olds ( = 5). The area, height, and subcutaneous fat depth of the LM were measured using ultrasonography, and BW and BCS were taken in October (Fall1), April (Spring), and October of the following year (Fall2). Satellite cells obtained from 10-d-old foals ( = 4) were cultured in the presence of IL-6, IL-1β, TNF-α, IGF-I, or FGF-2 before evaluation of proliferation and differentiation. Data were analyzed using PROC MIXED in SAS. Body weight increased from Fall1 to Spring in weanlings ( < 0.001) and increased in all horses from Spring to Fall2 ( ≤ 0.02). Area and height of the LM increased over time ( < 0.001) and with increasing age group of horse ( ≤ 0.03), although there was no interaction of time and age ( > 0.61). There was a significant increase in LM area in all animals from Spring to Fall2 ( < 0.001) but not from Fall1 to Spring. Interleukin-6 and TNF-α decreased satellite cell proliferation by 14.9 and 11.5%, respectively ( ≤ 0.01). Interleukin-6 increased fusion 6.2%, whereas TNF-α decreased fusion 8.7% compared with control cells ( ≤ 0.001). Interleukin-1β had no effect on proliferation ( = 0.32) but tended to decrease fusion ( = 0.06). Satellite cell proliferation was increased 28.8 and 73.0% by IGF-I and FGF-2, respectively ( < 0

  12. Structural aging program -- a summary of activities, results, and conclusions

    SciTech Connect

    Naus, D.J.; Oland, C.B.; Ellingwood, B.R.

    1997-01-01

    Research has been conducted by the Oak Ridge National Laboratory to address aging management of nuclear power plant concrete structures. The purpose was to identify potential structural safety issues and acceptance criteria for use in continued service assessments. Primary program accomplishments have included formulation of a Structural Materials Information Center that contains data and information on the time variation of material properties under the influence of pertinent environmental stressors and aging factors for 144 materials, an aging assessment methodology to identify critical structures and degradation factors that can potentially impact their performance, guidelines and evaluation criteria for use in condition assessments of reinforced concrete structures, and a reliability-based methodology for current condition assessments and estimations of future performance of reinforced concrete nuclear power plant structures. In addition, the Structural Aging Program conducted in-depth evaluations of several nondestructive evaluation and repair-related technologies to develop guidance on their applicability.

  13. Postnatal Growth and Psychomotor Development in Small for Gestational Age Brazilian Infants.

    ERIC Educational Resources Information Center

    Paine, Patricia Ann; Pasquali, Luiz

    1984-01-01

    The early psychomotor development (DQ) of 29 term small-for-gestational-age Brazilian infants was shown to be more dependent on postnatal growth than the DQ of 51 term appropriate-for-gestational-age infants. (Author/RH)

  14. Age and growth in the indian major carp Labeo rohita (Cypriniformes: Cyprinidae) from tropical rivers of Ganga basin, India.

    PubMed

    Mir, Javaid Iqbal; Sarkar, Uttam Kumar; Gusain, Om Prakash; Dwivedi, Arvind Kumar; Joukrushna, Jena

    2013-12-01

    Labeo rohita is a member of the Indian major carp species and originally an inhabitant of the Ganga river network in India. It is among the top ten aquaculture species of the world. Since there is a lack of information on the growth pattern of the wild populations of this species, this study aimed at evaluating the pattern of age and growth, to support the development of effective management plans. A total of 1082 samples of L. rohita were obtained from May 2009 to July 2012 in six drainages of the Ganga basin. Scales of the fish were used to determine the age and growth by analyzing the annual rings growth. Out of six populations, a maximum 8+ age classes were recorded from two rivers (Betwa and Sharda). The back-calculated lengths at 8+ age class ranged from 86.22 cm to 91.66 cm. However, for the rest of rivers up to 7+ age classes were recorded. Among growth parameters, specific rate of length increase (C(l)) and specific rate of weight increase (Cw) showed decreasing trend, and three distinct life stages of L. rohita were recorded based on growth constant data (C(lt)). Analysis of variance (ANOVA) of the back-calculated length data set of six populations indicated a significant difference (p < 0.05). All three populations showed significant variation in length attainment during 1+ and 3+ age groups, while two populations showed significant variation in length attainment during the 2+ and 7+ age classes. Additionally, analysis of age frequency at different length intervals indicated that with increase in age class, number of fish samples was reduced. Since the pattern of life history traits of L. rohita have not been attempted in the recent past; therefore, this study will guide fisheries biologists about the current stock structure of this fish across different spatial scale of the Ganga basin.

  15. Size, longevity and cancer: age structure

    PubMed Central

    2016-01-01

    There is significant recent interest in Peto's paradox and the related problem of the evolution of large, long-lived organisms in terms of cancer robustness. Peto's paradox refers to the expectation that large, long-lived organisms have a higher lifetime cancer risk, which is not the case: a paradox. This paradox, however, is circular: large, long-lived organisms are large and long-lived because they are cancer robust. Lifetime risk, meanwhile, depends on the age distributions of both cancer and competing risks: if cancer strikes before competing risks, then lifetime risk is high; if not, not. Because no set of competing risks is generally prevalent, it is instructive to temporarily dispose of competing risks and investigate the pure age dynamics of cancer under the multistage model of carcinogenesis. In addition to augmenting earlier results, I show that in terms of cancer-free lifespan large organisms reap greater benefits from an increase in cellular cancer robustness than smaller organisms. Conversely, a higher cellular cancer robustness renders cancer-free lifespan more resilient to an increase in size. This interaction may be an important driver of the evolution of large, cancer-robust organisms. PMID:27629030

  16. Age and structure of the southern Rockall Trough: New evidence

    NASA Astrophysics Data System (ADS)

    Roberts, D. G.; Masson, D. G.; Miles, P. R.

    1981-01-01

    The Rockall Trough separates the Rockall Plateau microcontinent from the shelf and slope west of the British Isles. The structure and age of the trough has been the source of considerable discussion. Although widely considered to be of oceanic origin, postulated ages for the spreading range from Permian to Cretaceous. New seismic profiles linked to the IPOD sites in the Bay of Biscay and to oceanic anomalies of known age are used to present a new assessment of the age and structure of the southern Rockall Trough. It is concluded that about 120 km of ocean crust is present in the trough and that spreading took place in the Albian-Maastrichtian interval.

  17. Anisotropic nanomaterials: structure, growth, assembly, and functions

    PubMed Central

    Sajanlal, Panikkanvalappil R.; Sreeprasad, Theruvakkattil S.; Samal, Akshaya K.; Pradeep, Thalappil

    2011-01-01

    Comprehensive knowledge over the shape of nanomaterials is a critical factor in designing devices with desired functions. Due to this reason, systematic efforts have been made to synthesize materials of diverse shape in the nanoscale regime. Anisotropic nanomaterials are a class of materials in which their properties are direction-dependent and more than one structural parameter is needed to describe them. Their unique and fine-tuned physical and chemical properties make them ideal candidates for devising new applications. In addition, the assembly of ordered one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D) arrays of anisotropic nanoparticles brings novel properties into the resulting system, which would be entirely different from the properties of individual nanoparticles. This review presents an overview of current research in the area of anisotropic nanomaterials in general and noble metal nanoparticles in particular. We begin with an introduction to the advancements in this area followed by general aspects of the growth of anisotropic nanoparticles. Then we describe several important synthetic protocols for making anisotropic nanomaterials, followed by a summary of their assemblies, and conclude with major applications. PMID:22110867

  18. Anisotropic nanomaterials: structure, growth, assembly, and functions.

    PubMed

    Sajanlal, Panikkanvalappil R; Sreeprasad, Theruvakkattil S; Samal, Akshaya K; Pradeep, Thalappil

    2011-01-01

    Comprehensive knowledge over the shape of nanomaterials is a critical factor in designing devices with desired functions. Due to this reason, systematic efforts have been made to synthesize materials of diverse shape in the nanoscale regime. Anisotropic nanomaterials are a class of materials in which their properties are direction-dependent and more than one structural parameter is needed to describe them. Their unique and fine-tuned physical and chemical properties make them ideal candidates for devising new applications. In addition, the assembly of ordered one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D) arrays of anisotropic nanoparticles brings novel properties into the resulting system, which would be entirely different from the properties of individual nanoparticles. This review presents an overview of current research in the area of anisotropic nanomaterials in general and noble metal nanoparticles in particular. We begin with an introduction to the advancements in this area followed by general aspects of the growth of anisotropic nanoparticles. Then we describe several important synthetic protocols for making anisotropic nanomaterials, followed by a summary of their assemblies, and conclude with major applications.

  19. Flexible alternatives to the Gompertz equation for describing growth with age in turkey hens.

    PubMed

    Porter, T; Kebreab, E; Darmani Kuhi, H; Lopez, S; Strathe, A B; France, J

    2010-02-01

    A total of 49 profiles of growing turkey hens from commercial flocks were used in this study. Three flexible growth functions (von Bertalanffy, Richards, and Morgan) were evaluated with regard to their ability to describe the relationship between BW and age and were compared with the Gompertz equation with its fixed point of inflection, which might result in its overestimation. For each function, 4 ways of analysis were implemented. A basic model was fitted first, followed by implementation of a first-order autoregressive correlation structure. A model that considered only mature BW varied with year and another that considered only the rate coefficient varied with different years were applied. The results showed that the fixed point of inflection of the Gompertz equation can be a limitation and that the relationship between BW and age in turkeys was best described using flexible growth functions. However, the Richards equation failed to converge when fitted to the turkey growth data; therefore, it was not considered further. Inclusion of an autoregressive process of the first order rendered a substantially improved fit to data for the 3 growth functions. The Morgan equation provided the best fit to the data set and was used for characterizing mean growth curves for the 7 yr of production. It was estimated that the maximum growth rate occurred at 3.74, 3.65, 3.99, 4.18, 4.05, 4.01, and 3.77 kg BW for production years from 1997 to 2003, respectively. It is recommended that flexible growth functions should be considered as an alternative to the simpler functions (with a fixed point of inflection) for describing the relationship between BW and age in turkeys because they were easier to fit and very often gave a closer fit to data points because of their flexibility, and therefore a smaller residual MS value, than simpler models. It can also be recommended that studies should consider adding a first-order autoregressive process when analyzing repeated measures data with

  20. Age determination and growth rate of Mactra chinensis (Bivalvia: Mactridae) by external rings and chondrophore growth bands

    NASA Astrophysics Data System (ADS)

    Kim, Jung Yeon; Na, Jong Hun; Oh, Chul-Woong

    2016-12-01

    Age, growth and mortality of Mactra chinensis were investigated during the period from October 2012 to September 2013 in Busan, South Korea. The monthly variation of the marginal index (MI) of the shell and chondrophore showed that the ring of this species was formed once a year during July. We estimated the age of M. chinensis by reading the external rings on the shell and the growth bands of the chondrophore to compare growth parameters between the two growth characters. The age of this species ranged from 0 to 8 years (shell-based age reading) and from 0 to 10 years (chondrophore-based age reading). Based on external rings and growth bands of chondrophore for the same period, the von Bertalanffy growth functions were expressed by the equation, L t = 101.53[1-exp {-0.15( t + 0.75)}] and L t = 90.03[1-exp {-0.20( t + 0.50)}], respectively. The likelihood test showed that there was a significant difference in L ∞ ( P < 0.001), K ( P < 0.001), to ( P < 0.001) estimated from non-linear regression between the two growth characters.

  1. Diverse Roles of Growth Hormone and Insulin-Like Growth Factor-1 in Mammalian Aging: Progress and Controversies

    PubMed Central

    Csiszar, Anna; de Cabo, Raphael; Ferrucci, Luigi; Ungvari, Zoltan

    2012-01-01

    Because the initial reports demonstrating that circulating growth hormone and insulin-like growth factor-1 decrease with age in laboratory animals and humans, there have been numerous studies related to the importance of these hormones for healthy aging. Nevertheless, the role of these potent anabolic hormones in the genesis of the aging phenotype remains controversial. In this chapter, we review the studies demonstrating the beneficial and deleterious effects of growth hormone and insulin-like growth factor-1 deficiency and explore their effects on specific tissues and pathology as well as their potentially unique effects early during development. Based on this review, we conclude that the perceived contradictory roles of growth hormone and insulin-like growth factor-1 in the genesis of the aging phenotype should not be interpreted as a controversy on whether growth hormone or insulin-like growth factor-1 increases or decreases life span but rather as an opportunity to explore the complex roles of these hormones during specific stages of the life span. PMID:22522510

  2. Diverse roles of growth hormone and insulin-like growth factor-1 in mammalian aging: progress and controversies.

    PubMed

    Sonntag, William E; Csiszar, Anna; deCabo, Raphael; Ferrucci, Luigi; Ungvari, Zoltan

    2012-06-01

    Because the initial reports demonstrating that circulating growth hormone and insulin-like growth factor-1 decrease with age in laboratory animals and humans, there have been numerous studies related to the importance of these hormones for healthy aging. Nevertheless, the role of these potent anabolic hormones in the genesis of the aging phenotype remains controversial. In this chapter, we review the studies demonstrating the beneficial and deleterious effects of growth hormone and insulin-like growth factor-1 deficiency and explore their effects on specific tissues and pathology as well as their potentially unique effects early during development. Based on this review, we conclude that the perceived contradictory roles of growth hormone and insulin-like growth factor-1 in the genesis of the aging phenotype should not be interpreted as a controversy on whether growth hormone or insulin-like growth factor-1 increases or decreases life span but rather as an opportunity to explore the complex roles of these hormones during specific stages of the life span.

  3. Communication breakdown: the impact of ageing on synapse structure.

    PubMed

    Petralia, Ronald S; Mattson, Mark P; Yao, Pamela J

    2014-03-01

    Impaired synaptic plasticity is implicated in the functional decline of the nervous system associated with ageing. Understanding the structure of ageing synapses is essential to understanding the functions of these synapses and their role in the ageing nervous system. In this review, we summarize studies on ageing synapses in vertebrates and invertebrates, focusing on changes in morphology and ultrastructure. We cover different parts of the nervous system, including the brain, the retina, the cochlea, and the neuromuscular junction. The morphological characteristics of aged synapses could shed light on the underlying molecular changes and their functional consequences.

  4. Growth at the Age of 4 Years Subsequent to Early Failure to Thrive.

    ERIC Educational Resources Information Center

    Kristiansson, Bengt; Fallstrom, Sven P.

    1987-01-01

    Followup at age 4 of 55 children, previously investigated for failure to thrive (FFT) at 4-18 months of age, indicated normal growth for most children with organic causes of FFT, but persisting suboptimal growth patterns for children with nonorganic FFT, particularly for those children with higher numbers of risk factors. (Author/DB)

  5. Communication Profile of Primary School-Aged Children with Foetal Growth Restriction

    ERIC Educational Resources Information Center

    Partanen, Lea Aulikki; Olsén, Päivi; Mäkikallio, Kaarin; Korkalainen, Noora; Heikkinen, Hanna; Heikkinen, Minna; Yliherva, Anneli

    2017-01-01

    Foetal growth restriction is associated with problems in neurocognitive development. In the present study, prospectively collected cohorts of foetal growth restricted (FGR) and appropriate for gestational age grown (AGA) children were examined at early school-age by using the Children's Communication Checklist-2 (CCC-2) to test the hypothesis that…

  6. The age structure of selected countries in the ESCAP region.

    PubMed

    Hong, S

    1982-01-01

    The study objective was to examine the age structure of selected countries in the Economic and Social Commission for Asia and the Pacific (ESCAP) region, using available data and frequently applied indices such as the population pyramid, aged-child ratio, and median age. Based on the overall picture of the age structure thus obtained, age trends and their implication for the near future were arrived at. Countries are grouped into 4 types based on the fertility and mortality levels. Except for Japan, Hong Kong, and Singapore, the age structure in the 18 ESCAP region countries changed comparatively little over the 1950-80 period. The largest structural change occurred in Singapore, where the proportion of children under age 15 in the population declined significantly from 41-27%, while that of persons 65 years and older more than doubled. This was due primarily to the marked decline in fertility from a total fertility rate (TFR) of 6.7-1.8 during the period. Hong Kong also had a similar major transformation during the same period: the proportion of the old age population increased 2 1/2 times, from 2.5-6.3%. The age structures of the 18 ESCAP countries varied greatly by country. 10 countries of the 2 high fertility and mortality types showed a similar young age structural pattern, i.e., they have higher dependency ratios, a higher proportion of children under 15 years, a lower proportion of population 65 years and older, lower aged-child ratios, and younger median ages than the average countries in the less developed regions of the world. With minimal changes over the 1950-80 period, the gap between these countries and the average of the less developed regions widened. Unlike these 10 (mostly South Asian) countries, moderately low fertility and mortality countries (China, Korea, and Sri Lanka) are located between the world average and the less developed region in most of the indices, particularly during the last decade. Although their rate of population aging is not

  7. Age and growth of alewives in the changing pelagia of Lake Ontario, 1978-1992

    USGS Publications Warehouse

    O'Gorman, Robert; Johannsson, Ora E.; Schneider, Clifford P.

    1997-01-01

    We documented the age and growth of alewives Alosa pseudoharenqus in Lake Ontario during 1978-1992 and determined if growth was affected by intraspecific competition for epilimnetic zooplankton, lake temperature, or demand of salmonine piscivores for prey. Ages of juvenile alewives were determined from scales during 1978-1983, and ages of juvenile and adult alewives were determined from otoliths during 1984-1992. Indices of abundance for alewives were calculated from spring bottom trawl catches in 1978-1992; zooplankton density and epilimnetic temperature were monitored at two stations during 1981-1991; and salmonine demand each year during 1978-1992 was calculated with a simulation model. Although we encountered 11-year-old alewives, few fish lived longer than 7 years, and most fish in the population were younger than 6 years. Mean sizes at ages 1, 2, and 3 in spring averaged 93 mm (5.1 g), 133 mm (17 g), and 149 mm (22 g), but from age 3 to age 8, mean size increased by only 5-7 mm and 2-3 g per year. Female alewives lived longer than male alewives and were always longer than male alewives at age 4 and older. Epilimnetic temperatures were suitable for rapid growth of juvenile alewives each year. Lake temperature had the potential to affect growth of adults but adult growth was not correlated with temperature suitability indices perhaps because temperature regimes differed among lake regions and alewives were mobile. Growth of alewives was not correlated with salmonine demand for prey. Competition for zooplankton among the two youngest alewife cohorts affected growth of age-1 alewives. Zooplankton density declined sharply in 1986, and should it decline again, growth of age-1 alewives will slow, unless numbers of age-0 alewives fall. Whether growth of age-1 fish declines or numbers of age-0 fish fall, the result of another decline in zooplankton density will be a reduction in the production of alewives needed to support piscivores.

  8. Age effect on subcortical structures in healthy adults

    PubMed Central

    Goodro, Matt; Sameti, Mohammad; Patenaude, Brian; Fein, George

    2012-01-01

    Cross-sectional age effects in normal control volunteers were investigated in 8 subcortical structures: lateral ventricles, thalamus, caudate, putamen, pallidum, hippocampus, amygdala and nucleus accumbens. Two hundred and twenty six control subjects, ranging in age from 19 to 85 years, were scanned on a 1.5T GE system (n = 184) or a 3.0T Siemens system (n = 42). Cranium-size adjusted subcortical structure volumes were estimated using FSL’s FIRST software, which is fully automated. Significant age effects were found for all volumes when the entire age range was analyzed, however the older subjects (60–85 years of age) showed a stronger correlation between age and structural volume for the ventricles, hippocampus, amygdala and accumbens than middle-aged (35–60 years of age) subjects. Middle-aged subjects were studied at both sites, and age effects in these groups were comparable, despite differences in magnet strength and acquisition systems. This agreement lends support to the validity of the image analysis tools and procedures used in the present study. PMID:22863654

  9. The immune-endocrine loop during aging: role of growth hormone and insulin-like growth factor-I.

    PubMed

    Burgess, W; Liu, Q; Zhou, J; Tang, Q; Ozawa, A; VanHoy, R; Arkins, S; Dantzer, R; Kelley, K W

    1999-01-01

    Why a primary lymphoid organ such as the thymus involutes during aging remains a fundamental question in immunology. Aging is associated with a decrease in plasma growth hormone (somatotropin) and IGF-I, and this somatopause of aging suggests a connection between the neuroendocrine and immune systems. Several investigators have demonstrated that treatment with either growth hormone or IGF-I restores architecture of the involuted thymus gland by reversing the loss of immature cortical thymocytes and preventing the decline in thymulin synthesis that occurs in old or GH-deficient animals and humans. The proliferation, differentiation and functions of other components of the immune system, including T and B cells, macrophages and neutrophils, also demonstrate age-associated decrements that can be restored by IGF-I. Knowledge of the mechanism by which cytokines and hormones influence hematopoietic cells is critical to improving the health of aged individuals. Our laboratory has recently demonstrated that IGF-I prevents apoptosis in promyeloid cells, which subsequently permits these cells to differentiate into neutrophils. We also demonstrated that IL-4 acts much like IGF-I to promote survival of promyeloid cells and to activate the enzyme phosphatidylinositol 3'-kinase (PI 3-kinase). However, the receptors for IGF-I and IL-4 are completely different, with the intracellular beta chains of the IGF receptor possessing intrinsic tyrosine kinase activity and the alpha and gammac subunit of the heterodimeric IL-4 receptor utilizing the Janus kinase family of nonreceptor protein kinases to tyrosine phosphorylate downstream targets. Both receptors share many of the components of the PI 3-kinase signal transduction pathway, converging at the level of insulin receptor substrate-1 or insulin receptor subtrate-2 (formally known as 4PS, or IL-4 Phosphorylated Substrate). Our investigations with IGF-I and IL-4 suggest that PI 3-kinase inhibits apoptosis by maintaining high levels of

  10. Statistical method for detecting structural change in the growth process.

    PubMed

    Ninomiya, Yoshiyuki; Yoshimoto, Atsushi

    2008-03-01

    Due to competition among individual trees and other exogenous factors that change the growth environment, each tree grows following its own growth trend with some structural changes in growth over time. In the present article, a new method is proposed to detect a structural change in the growth process. We formulate the method as a simple statistical test for signal detection without constructing any specific model for the structural change. To evaluate the p-value of the test, the tube method is developed because the regular distribution theory is insufficient. Using two sets of tree diameter growth data sampled from planted forest stands of Cryptomeria japonica in Japan, we conduct an analysis of identifying the effect of thinning on the growth process as a structural change. Our results demonstrate that the proposed method is useful to identify the structural change caused by thinning. We also provide the properties of the method in terms of the size and power of the test.

  11. Pattern, growth, and aging in aggregation kinetics of a Vicsek-like active matter model

    NASA Astrophysics Data System (ADS)

    Das, Subir K.

    2017-01-01

    Via molecular dynamics simulations, we study kinetics in a Vicsek-like phase-separating active matter model. Quantitative results, for isotropic bicontinuous pattern, are presented on the structure, growth, and aging. These are obtained via the two-point equal-time density-density correlation function, the average domain length, and the two-time density autocorrelation function. Both the correlation functions exhibit basic scaling properties, implying self-similarity in the pattern dynamics, for which the average domain size exhibits a power-law growth in time. The equal-time correlation has a short distance behavior that provides reasonable agreement between the corresponding structure factor tail and the Porod law. The autocorrelation decay is a power-law in the average domain size. Apart from these basic similarities, the overall quantitative behavior of the above-mentioned observables is found to be vastly different from those of the corresponding passive limit of the model which also undergoes phase separation. The functional forms of these have been quantified. An exceptionally rapid growth in the active system occurs due to fast coherent motion of the particles, mean-squared-displacements of which exhibit multiple scaling regimes, including a long time ballistic one.

  12. Benefits of gregarious feeding by aposematic caterpillars depend on group age structure.

    PubMed

    Campbell, Stuart A; Stastny, Michael

    2015-03-01

    Gregarious feeding is a common feature of herbivorous insects and can range from beneficial (e.g. dilution of predation risk) to costly (e.g. competition). Group age structure should influence these costs and benefits, particularly when old and young larvae differ in their feeding mode or apparency to predators. We investigated the relative value of gregarious feeding by aposematic larvae of Uresiphita reversalis that we observed feeding in groups of mixed ages and variable densities on wild Lupinus diffusus. In a manipulative field experiment, the survivorship and growth of young larvae were enhanced in the presence of older conspecifics, but not in large groups of similarly aged larvae. Estimates of insect damage and induced plant responses suggest that mixed-age groups enhance plant quality for young larvae while avoiding competition. We conclude that benefits of gregariousness in this species are contingent on group age structure, a finding of significance for the ecology and evolution of gregariousness and other social behaviours.

  13. CVD Growth of Carbon Nanotubes: Structure, Catalyst, and Growth

    NASA Technical Reports Server (NTRS)

    Delzeit, Lance

    2003-01-01

    Carbon nanotubes (CNTs) exhibit extraordinary mechanical and unique electronic properties and hence have been receiving much attention in recent years for their potential in nanoelectronics, field emission devices, scanning probes, high strength composites and many more applications. Catalytic decomposition of hydrocarbon feedstock with the aid of supported transition metal catalysts - also known as chemical vapor deposition (CVD) - has become popular to produce single-walled and multi-walled nanotubes (SWNTs, MWNTs) and multiwalled nanofibers (MWNFs). The ability to grow CNTs on patterned substrates and in vertically aligned arrays, and the simplicity of the process, has made CVD growth of CNTs an attractive approach.

  14. Posttraumatic symptom structure across age groups.

    PubMed

    Helpman, Liat; Rachamim, Lilach; Aderka, Idan M; Gabai-Daie, Ayala; Schindel-Allon, Inbal; Gilboa-Schechtman, Eva

    2015-01-01

    The applicability of diagnostic criteria of Posttraumatic Stress Disorder to the pediatric population has been a focus of much debate (e.g., Carrion, Weems, Ray, & Reiss, 2002 ), informing changes in the Diagnostic and Statistical Manual of Mental Disorders (5th ed.; DSM-5). The current study examined the factor structure of posttraumatic distress among adult versus pediatric samples using confirmatory factor analysis. The analysis was performed on the DSM-IV-adherent Posttraumatic Diagnostic Scale (Foa, Cashman, Jaycox, & Perry, 1997 ) and Child Posttraumatic Symptom Scale (Foa, Johnson, Feeny, & Treadwell, 2001 ). The sample included 378 adult and 204 child and adolescent victims of diverse single-event traumas. A series of models based on previous findings and DSM-IV specification were evaluated. A 4-factor model (Intrusions, Avoidance, Dysphoria, and Hyperarousal), similar to the DSM-5 model, best fit the data among adults, and a different 4-factor model (Intrusion, Avodiance, Numbing, and Hyperarousal) best fit the data among children and adolescents. Despite some similarity, the posttraumatic symptom profiles of pediatric and adult samples may differ. These differences are not fully incorporated into the DSM-5, and warrant further examination.

  15. Structure and Age Jointly Influence Rates of Protein Evolution

    PubMed Central

    Toll-Riera, Macarena; Bostick, David; Albà, M. Mar; Plotkin, Joshua B.

    2012-01-01

    What factors determine a protein's rate of evolution are actively debated. Especially unclear is the relative role of intrinsic factors of present-day proteins versus historical factors such as protein age. Here we study the interplay of structural properties and evolutionary age, as determinants of protein evolutionary rate. We use a large set of one-to-one orthologs between human and mouse proteins, with mapped PDB structures. We report that previously observed structural correlations also hold within each age group – including relationships between solvent accessibility, designabililty, and evolutionary rates. However, age also plays a crucial role: age modulates the relationship between solvent accessibility and rate. Additionally, younger proteins, despite being less designable, tend to evolve faster than older proteins. We show that previously reported relationships between age and rate cannot be explained by structural biases among age groups. Finally, we introduce a knowledge-based potential function to study the stability of proteins through large-scale computation. We find that older proteins are more stable for their native structure, and more robust to mutations, than younger ones. Our results underscore that several determinants, both intrinsic and historical, can interact to determine rates of protein evolution. PMID:22693443

  16. Shame, hope, intimacy and growth: Dementia distress and growth in families from the perspective of senior aged care professionals.

    PubMed

    Walmsley, Bruce; McCormack, Lynne

    2016-11-01

    Minimal research explores the impact of dementia and a dementia diagnosis on families from the unique vantage of senior health professionals. The participants of this study, eight senior aged care professionals, provided unique interpretative insights into family dynamics and sense-making on the journey with dementia, and their own role in that journey. Both positive and negative perspectives were sought. Data from semi-structured interviews were analysed using Interpretative Phenomenological Analysis (IPA). One superordinate theme, Dementia naiveté; redefined intimacy, overarched Embarrassed shame; Maintaining hope; Redefining a model of intimacy; and Redefined relational intimacy and growth Within these themes, the participants shed light on hurtful embarrassment and shame experienced by families associated with the diagnostic label given to a loved one. This label was perceived to either trigger separation, hurt and immobility through ignorance, or precipitate a frenzy of naive yet hopeful energy for seeking that elusive cure. The participants saw their role as one of enacting a new way of connecting what was with what could be. Thus, they modelled advocacy, integral care and relational intimacy. Validation came in witnessing a redefining of intimacy in many families who were able to embrace that holistic and empathic approach to the shifting presentation of dementia. Psychological well-being was observed to occur when families embraced growthful domains, e.g. acceptance, hope, relational closeness and altruistic concern for other families. Implications for future care models are discussed.

  17. China's marriage squeeze: A decomposition into age and sex structure.

    PubMed

    Jiang, Quanbao; Li, Xiaomin; Li, Shuzhuo; Feldman, Marcus W

    2016-06-01

    Most recent studies of marriage patterns in China have emphasized the male-biased sex ratio but have largely neglected age structure as a factor in China's male marriage squeeze. In this paper we develop an index we call "spousal sex ratio" (SSR) to measure the marriage squeeze, and a method of decomposing the proportion of male surplus into age and sex structure effects within a small spousal age difference interval. We project that China's marriage market will be confronted with a relatively severe male squeeze. For the decomposition of the cohort aged 30, from 2010 to 2020 age structure will be dominant, while from 2020 through 2034 the contribution of age structure will gradually decrease and that of sex structure will increase. From then on, sex structure will be dominant. The index and decomposition, concentrated on a specific female birth cohort, can distinguish spousal competition for single cohorts which may be covered by a summary index for the whole marriage market; these can also be used for consecutive cohorts to reflect the situation of the whole marriage market.

  18. Growth impairment shows an age-dependent pattern in boys with chronic kidney disease.

    PubMed

    Zivicnjak, Miroslav; Franke, Doris; Filler, Guido; Haffner, Dieter; Froede, Kerstin; Nissel, Richard; Haase, Sanny; Offner, Gisela; Ehrich, Jochen H H; Querfeld, Uwe

    2007-03-01

    The impact of chronological age on longitudinal body growth from early childhood through adolescence using detailed anthropometric methods has not yet been studied in children with chronic kidney disease (CKD). We have evaluated growth failure by measuring four components of linear growth: body height (HT), sitting height (SHT), arm length (AL) and leg length (LL). Data were prospectively collected for up to 7 years on 190 boys (3-21 years old) with congenital or hereditary CKD (all had developed at least stage 2 CKD by the age of 10 years). Patients showed the most severe growth failure in early childhood, followed by an acceleration in growth in pre-puberty, a slowing-down of growth at puberty, as expected, and thereafter a late speeding-up of growth until early adulthood. This pattern was observed irrespective of the degree of CKD and different treatment modalities, such as conservative treatment, recombinant human growth hormone (rhGH) therapy or transplantation. LL showed the most dynamic growth changes of all the parameters evaluated and emerged as the best indicator of statural growth in children with CKD. A specific age-dependent pattern of physical growth was identified in pediatric male CKD patients. This growth pattern should be considered in the evaluation of individual growth and the assessment of treatment efficacy such as rhGH therapy.

  19. The Aging Mind Proves Capable of Lifelong Growth.

    ERIC Educational Resources Information Center

    Goleman, Daniel

    1984-01-01

    Current research shows that, while fluid intelligence may decline with age, crystallized intelligence continues to rise over the life span. Key factors in maintaining mental capabilities include staying socially involved, being mentally active, and being flexible. (SK)

  20. Aging management of containment structures in nuclear power plants

    SciTech Connect

    Naus, D.J.; Oland, C.B.; Ellingwood, B.R.; Graves, H.L. III; Norris, W.E.

    1994-12-31

    Research is being conducted by ORNL under US Nuclear Regulatory Commission (USNRC) sponsorship to address aging management of nuclear power plant containment and other safety-related structures. Documentation is being prepared to provide the USNRC with potential structural safety issues and acceptance criteria for use in continued service evaluations of nuclear power plants. Accomplishments include development of a Structural Materials Information Center containing data and information on the time variation of 144 material properties under the influence of pertinent environmental stressors or aging factors, evaluation of models for potential concrete containment degradation factors, development of a procedure to identify critical structures and degradation factors important to aging management, evaluations of nondestructive evaluation techniques. assessments of European and North American repair practices for concrete, review of parameters affecting corrosion of metals embedded in concrete, and development of methodologies for making current condition assessments and service life predictions of new or existing reinforced concrete structures in nuclear power plants.

  1. Age-structured optimal control in population economics.

    PubMed

    Feichtinger, Gustav; Prskawetz, Alexia; Veliov, Vladimir M

    2004-06-01

    This paper brings both intertemporal and age-dependent features to a theory of population policy at the macro-level. A Lotka-type renewal model of population dynamics is combined with a Solow/Ramsey economy. We consider a social planner who maximizes an aggregate intertemporal utility function which depends on per capita consumption. As control policies we consider migration and saving rate (both age-dependent). By using a new maximum principle for age-structured control systems we derive meaningful results for the optimal migration and saving rate in an aging population. The model used in the numerical calculations is calibrated for Austria.

  2. Demographic analysis from summaries of an age-structured population.

    PubMed

    Link, William A; Royle, J Andrew; Hatfield, Jeff S

    2003-12-01

    Demographic analyses of age-structured populations typically rely on life history data for individuals, or when individual animals are not identified, on information about the numbers of individuals in each age class through time. While it is usually difficult to determine the age class of a randomly encountered individual, it is often the case that the individual can be readily and reliably assigned to one of a set of age classes. For example, it is often possible to distinguish first-year from older birds. In such cases, the population age structure can be regarded as a latent variable governed by a process prior, and the data as summaries of this latent structure. In this article, we consider the problem of uncovering the latent structure and estimating process parameters from summaries of age class information. We present a demographic analysis for the critically endangered migratory population of whooping cranes (Grus americana), based only on counts of first-year birds and of older birds. We estimate age and year-specific survival rates. We address the controversial issue of whether management action on the breeding grounds has influenced recruitment, relating recruitment rates to the number of seventh-year and older birds, and examining the pattern of variation through time in this rate.

  3. Demographic analysis from summaries of an age-structured population

    USGS Publications Warehouse

    Link, William A.; Royle, J. Andrew; Hatfield, Jeff S.

    2003-01-01

    Demographic analyses of age-structured populations typically rely on life history data for individuals, or when individual animals are not identified, on information about the numbers of individuals in each age class through time. While it is usually difficult to determine the age class of a randomly encountered individual, it is often the case that the individual can be readily and reliably assigned to one of a set of age classes. For example, it is often possible to distinguish first-year from older birds. In such cases, the population age structure can be regarded as a latent variable governed by a process prior, and the data as summaries of this latent structure. In this article, we consider the problem of uncovering the latent structure and estimating process parameters from summaries of age class information. We present a demographic analysis for the critically endangered migratory population of whooping cranes (Grus americana), based only on counts of first-year birds and of older birds. We estimate age and year-specific survival rates. We address the controversial issue of whether management action on the breeding grounds has influenced recruitment, relating recruitment rates to the number of seventh-year and older birds, and examining the pattern of variation through time in this rate.

  4. 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.

  5. Effect of growth hormone deficiency on brain structure, motor function and cognition.

    PubMed

    Webb, Emma A; O'Reilly, Michelle A; Clayden, Jonathan D; Seunarine, Kiran K; Chong, Wui K; Dale, Naomi; Salt, Alison; Clark, Chris A; Dattani, Mehul T

    2012-01-01

    The growth hormone-insulin-like growth factor-1 axis plays a role in normal brain growth but little is known of the effect of growth hormone deficiency on brain structure. Children with isolated growth hormone deficiency (peak growth hormone <6.7 µg/l) and idiopathic short stature (peak growth hormone >10 µg/l) underwent cognitive assessment, diffusion tensor imaging and volumetric magnetic resonance imaging prior to commencing growth hormone treatment. Total brain, corpus callosal, hippocampal, thalamic and basal ganglia volumes were determined using Freesurfer. Fractional anisotropy (a marker of white matter structural integrity) images were aligned and tract-based spatial statistics performed. Fifteen children (mean 8.8 years of age) with isolated growth hormone deficiency [peak growth hormone <6.7 µg/l (mean 3.5 µg/l)] and 14 controls (mean 8.4 years of age) with idiopathic short stature [peak growth hormone >10 µg/l (mean 15 µg/l) and normal growth rate] were recruited. Compared with controls, children with isolated growth hormone deficiency had lower Full-Scale IQ (P < 0.01), Verbal Comprehension Index (P < 0.01), Processing Speed Index (P < 0.05) and Movement-Assessment Battery for Children (P < 0.008) scores. Verbal Comprehension Index scores correlated significantly with insulin-like growth factor-1 (P < 0.03) and insulin-like growth factor binding protein-3 (P < 0.02) standard deviation scores in isolated growth hormone deficiency. The splenium of the corpus callosum, left globus pallidum, thalamus and hippocampus (P < 0.01) were significantly smaller; and corticospinal tract (bilaterally; P < 0.045, P < 0.05) and corpus callosum (P < 0.05) fractional anisotropy were significantly lower in the isolated growth hormone deficiency group. Basal ganglia volumes and bilateral corticospinal tract fractional anisotropy correlated significantly with Movement-Assessment Battery for Children scores, and

  6. Aging Theories for Establishing Safe Life Spans of Airborne Critical Structural Components

    NASA Technical Reports Server (NTRS)

    Ko, William L.

    2003-01-01

    New aging theories have been developed to establish the safe life span of airborne critical structural components such as B-52B aircraft pylon hooks for carrying air-launch drop-test vehicles. The new aging theories use the equivalent-constant-amplitude loading spectrum to represent the actual random loading spectrum with the same damaging effect. The crack growth due to random loading cycling of the first flight is calculated using the half-cycle theory, and then extrapolated to all the crack growths of the subsequent flights. The predictions of the new aging theories (finite difference aging theory and closed-form aging theory) are compared with the classical flight-test life theory and the previously developed Ko first- and Ko second-order aging theories. The new aging theories predict the number of safe flights as considerably lower than that predicted by the classical aging theory, and slightly lower than those predicted by the Ko first- and Ko second-order aging theories due to the inclusion of all the higher order terms.

  7. Evaluation of the feasibility of international growth standards for school-aged children and adolescents.

    PubMed

    Butte, Nancy F; Garza, Cutberto; de Onis, Mercedes

    2007-01-01

    The development of an international growth standard for the screening, surveillance, and monitoring of school-aged children and adolescents has been motivated by 2 contemporaneous events, the global surge in childhood obesity and the release of a new international growth standard for infants and preschool children by the WHO. If a prescriptive approach analogous to that taken by WHO for younger children is to be adopted for school-aged children and adolescents, several issues need to be addressed regarding the universality of growth potential across populations and the definition of optimal growth in children and adolescents. A working group of experts in growth and development and representatives from international organizations concluded that subpopulations exhibit similar patterns of growth when exposed to similar external conditioners of growth. However, based on available data, we cannot rule out that observed differences in linear growth across ethnic groups reflect true differences in genetic potential rather than environmental influences. Therefore, the sampling frame for the development of an international growth standard for children and adolescents must include multiethnic sampling strategies designed to capture the variation in human growth patterns. A single international growth standard for school-aged children and adolescents could be developed with careful consideration of the population and individual selection criteria, study design, sample size, measurements, and statistical modeling of primary growth and secondary ancillary data. The working group agreed that existing growth references for school-aged children and adolescents have shortcomings, particularly for assessing obesity, and that appropriate growth standards for these age groups should be developed for clinical and public health applications.

  8. Exposure to omega-3 fatty acids at early age accelerate bone growth and improve bone quality.

    PubMed

    Koren, Netta; Simsa-Maziel, Stav; Shahar, Ron; Schwartz, Betty; Monsonego-Ornan, Efrat

    2014-06-01

    Omega-3 fatty acids (FAs) are essential nutritional components that must be obtained from foods. Increasing evidence validate that omega-3 FAs are beneficial for bone health, and several mechanisms have been suggested to mediate their effects on bone, including alterations in calcium absorption and urinary calcium loss, prostaglandin synthesis, lipid oxidation, osteoblast formation and inhibition of osteoclastogenesis. However, to date, there is scant information regarding the effect of omega-3 FAs on the developing skeleton during the rapid growth phase. In this study we aim to evaluate the effect of exposure to high levels of omega-3 FAs on bone development and quality during prenatal and early postnatal period. For this purpose, we used the fat-1 transgenic mice that have the ability to convert omega-6 to omega-3 fatty acids and the ATDC5 chondrogenic cell line as models. We show that exposure to high concentrations of omega-3 FAs at a young age accelerates bone growth through alterations of the growth plate, associated with increased chondrocyte proliferation and differentiation. We further propose that those effects are mediated by the receptors G-protein coupled receptor 120 (GPR120) and hepatic nuclear factor 4α, which are expressed by chondrocytes in culture. Additionally, using a combined study on the structural and mechanical bone parameters, we show that high omega-3 levels contribute to superior trabecular and cortical structure, as well as to stiffer bones and improved bone quality. Most interestingly, the fat-1 model allowed us to demonstrate the role of maternal high omega-3 concentration on bone growth during the gestation and postnatal period.

  9. Structural developmental psychology and health promotion in the third age.

    PubMed

    Bauger, Lars; Bongaardt, Rob

    2017-01-12

    In response to the ever-increasing longevity in Western societies, old age has been divided into two different periods, labelled the third and fourth age. Where the third age, with its onset at retirement, mostly involves positive aspects of growing old, the fourth age involves functional decline and increased morbidity. This article focuses on the entry to the third age and its potential for health promotion initiatives. Well-being is an important factor to emphasize in such health promotion, and this article views the lifestyle of third agers as essential for their well-being. The structural developmental theory of Robert Kegan delineates how a person's way of knowing develops throughout the life course. This theory is an untapped and salient perspective for health promotion initiatives in the third age. This article outlines Kegan's approach as a tool for developing psychologically spacious health promotion, and suggests future directions for research on the topic.

  10. Age and growth of pike (Esox lucius) in Chivyrkui Bay, Lake Baikal

    USGS Publications Warehouse

    Owens, Randall W.; Pronin, Nikolai M.

    2000-01-01

    The purpose of this study was to describe age and growth of pike (Esox lucius) in Lake Baikal. Pike were collected with gill nets and by angling in Chivyrkui Bay in late July-early August 1993 and by gill nets in June 1995. Total length (mm), weight (g), and sex were recorded and scales and cleithra were collected for aging. In 1993, pike, ages 1 to 3, ranged in length from 331 to 810 mm and in 1995 , pike, ages 2 to 10, ranged in length from 365 to 1,111 mm but only three percent were age 7 or older. Most growth in length occurred during the first two years of life. The length-weight relation for pike from Chivyrkui Bay was similar to that of pike from the St. Lawrence River. Calculated total length of pike from Lake Baikal equalled or exceeded the lengths of pike from lakes Erie or Ontario. Good agreement was found between ages from cleithra and from scales. Lengths at age in June 1995 (N=108) varied widely among pike. Females were generally larger than males at a given age among fish age-3 and older. When compared with the circumpolar growth standard, based on the von Bertalanffy growth curve, growth of Lake Baikal pike exceeded all other Asian populations, and equalled or exceeded many other northern hemisphere populations.

  11. Atrial structure, function and arrhythmogenesis in aged and frail mice

    PubMed Central

    Jansen, Hailey J.; Moghtadaei, Motahareh; Mackasey, Martin; Rafferty, Sara A.; Bogachev, Oleg; Sapp, John L.; Howlett, Susan E.; Rose, Robert A.

    2017-01-01

    Atrial fibrillation (AF) is prevalent in aging populations; however not all individuals age at the same rate. Instead, individuals of the same chronological age can vary in health status from fit to frail. Our objective was to determine the impacts of age and frailty on atrial function and arrhythmogenesis in mice using a frailty index (FI). Aged mice were more frail and demonstrated longer lasting AF compared to young mice. Consistent with this, aged mice showed longer P wave duration and PR intervals; however, both parameters showed substantial variability suggesting differences in health status among mice of similar chronological age. In agreement with this, P wave duration and PR interval were highly correlated with FI score. High resolution optical mapping of the atria demonstrated reduced conduction velocity and action potential duration in aged hearts that were also graded by FI score. Furthermore, aged mice had increased interstitial fibrosis along with changes in regulators of extracellular matrix remodelling, which also correlated with frailty. These experiments demonstrate that aging results in changes in atrial structure and function that create a substrate for atrial arrhythmias. Importantly, these changes were heterogeneous due to differences in health status, which could be identified using an FI. PMID:28290548

  12. Growth pattern from birth to adulthood in African pygmies of known age

    PubMed Central

    Rozzi, Fernando V. Ramirez; Koudou, Yves; Froment, Alain; Le Bouc, Yves; Botton, Jérémie

    2015-01-01

    The African pygmy phenotype stems from genetic foundations and is considered to be the product of a disturbance in the growth hormone–insulin-like growth factor (GH–IGF) axis. However, when and how the pygmy phenotype is acquired during growth remains unknown. Here we describe growth patterns in Baka pygmies based on two longitudinal studies of individuals of known age, from the time of birth to the age of 25 years. Body size at birth among the Baka is within standard limits, but their growth rate slows significantly during the first two years of life. It then more or less follows the standard pattern, with a growth spurt at adolescence. Their life history variables do not allow the Baka to be distinguished from other populations. Therefore, the pygmy phenotype in the Baka is the result of a change in growth that occurs during infancy, which differentiates them from East African pygmies revealing convergent evolution. PMID:26218408

  13. Expert Group Meeting on Population Growth and Demographic Structure.

    PubMed

    1993-01-01

    As part of the preparation for the forth-coming UN International Conference on Population and Development, an expert group met in Paris, France, in November 1992 to discuss population growth and demographic structure. As part of the demographic background for the meeting provided by the UN Population Division, participants were informed that although the world population growth rate began to decline in the late 1970s, this decline has not yet resulted in declining absolute numbers, and the annual increment to the world population was not expected to decline to the level that existed in 1985 until the period 2020-25. World population increased from 2.5 billion in 1950 to 5.3 billion in 1990. The medium variant population projection of the UN shows world population at 6.3 billion in 2000 and 8.5 billion in 2025 (the high variant shows 9.4 billion in 2025 and the low variant shows 7.6 billion). Population aging is expected to reach unparalleled levels in 2010-20. The meeting then considered the topics of population growth and socioeconomic development, confronting poverty in developing countries, demographic impacts of development patterns, demographic and health transitions, population growth and employment, social change and the elderly in developing countries, and social development and ageing in developed countries, The expert group meeting then prepared 19 recommendations aimed at governments, social institutions, and the international community. The recommendations call for political commitment to human resources development and population and development programs, especially in least developed countries, alleviation of poverty and social inequality, and equality of access to social and health resources that will lead to reduced mortality and fertility. Governments are urged to place a high priority on education and on increasing women's access to education and to remove barriers to economic independence for women. Health-sector priorities should be reassessed

  14. Age, growth, and mortality of introduced flathead catfish in Atlantic rivers and a review of other populations

    USGS Publications Warehouse

    Kwak, T.J.; Pine, William E.; Waters, D.S.

    2006-01-01

    Knowledge of individual growth and mortality rates of an introduced fish population is required to determine the success and degree of establishment as well as to predict the fish's impact on native fauna. The age and growth of flathead catfish Pylodictis olivaris have been studied extensively in the species' native and introduced ranges, and estimates have varied widely. We quantified individual growth rates and age structure of three introduced flathead catfish populations in North Carolina's Atlantic slope rivers using sagittal otoliths, determined trends in growth rates over time, compared these estimates among rivers in native and introduced ranges, and determined total mortality rates for each population. Growth was significantly faster in the Northeast Cape Fear River (NECFR) than in the Lumber and Neuse rivers. Fish in the NECFR grew to a total length of 700 mm by age 7, whereas fish in the Neuse and Lumber river populations reached this length by 8 and 10 years, respectively. The growth rates of fish in all three rivers were consistently higher than those of native riverine populations, similar to those of native reservoir populations, and slower than those of other introduced riverine populations. In general, recent cohorts (1998-2001 year-classes) in these three rivers exhibited slower growth among all ages than did cohorts previous to the 1998 year-class. The annual total mortality rate was similar among the three rivers, ranging from 0.16 to 0.20. These mortality estimates are considerably lower than those from the Missouri and Mississippi rivers, suggesting relatively low fishing mortality for these introduced populations. Overall, flathead catfish populations in reservoirs grow faster than those in rivers, the growth rates of introduced populations exceed those of native populations, and eastern United States populations grow faster than those in western states. Such trends constitute critical information for understanding and managing local

  15. Effect of Giardia infection on growth and psychomotor development of children aged 0-5 years.

    PubMed

    Simsek, Z; Zeyrek, F Yildiz; Kurcer, M A

    2004-04-01

    Giardiasis, an intestinal protozoan infection caused by Giardia intestinalis, is common in southeastern Anatolia, Turkey. In this cross-sectional survey, to investigate the role of giardiasis on growth and psychomotor development, we studied 160 children aged 0-5 years. Data were collected using a structured questionnaire, anthropometry, Ankara Developmental Screening Inventory, and laboratory analysis of fecal samples. The results showed that 50 per cent of the subjects were infected with at least one pathogen of intestinal parasitic infections. Giardia intestinalis was the most frequent pathogenic parasite. Giardia-infected children had a risk for stunted (OR = 7.67, 95 per cent CI = 2.25-26.16; p = 0.001) and poor psychomotor development (OR = 2.68, 95 per cent CI = 1.09-6.58; p = 0.030). The data indicate that Giardia intestinalis infection has an adverse impact on child linear growth and psychomotor development. In the primary healthcare centers, during the programme of the monitoring growth and developmental status of children, following children in terms of Giardia, diagnosis and treatment will have a positive effect on child health.

  16. Growth of cosmic structure: Probing dark energy beyond expansion

    NASA Astrophysics Data System (ADS)

    Huterer, Dragan; Kirkby, David; Bean, Rachel; Connolly, Andrew; Dawson, Kyle; Dodelson, Scott; Evrard, August; Jain, Bhuvnesh; Jarvis, Michael; Linder, Eric; Mandelbaum, Rachel; May, Morgan; Raccanelli, Alvise; Reid, Beth; Rozo, Eduardo; Schmidt, Fabian; Sehgal, Neelima; Slosar, Anže; van Engelen, Alex; Wu, Hao-Yi; Zhao, Gongbo

    2015-03-01

    curvature, high density regime. Cosmological evolution provides a polar opposite test bed, probing how gravity behaves in the lowest curvature, low density environments. There are a number of different implementations of astrophysically relevant modifications of gravity. Generically, the models are able to reproduce the distance measurements while at the same time altering the growth of structure. In particular, as detailed below, the Poisson equation relating over-densities to gravitational potentials is altered, and the potential that determines the geodesics of relativistic particles (such as photons) differs from the potential that determines the motion of non-relativistic particles. Upcoming surveys will exploit these differences to determine whether the acceleration of the Universe is due to dark energy or to modified gravity. To realize this potential, both wide field imaging and spectroscopic redshift surveys play crucial roles. Projects including DES, eBOSS, DESI, PFS, LSST, Euclid, and WFIRST are in line to map more than a 1000 cubic-billion-light-year volume of the Universe. These will map the cosmic structure growth rate to 1% in the redshift range 0 < z < 2 , over the last 3/4 of the age of the Universe.

  17. Population age structure and asset returns: an empirical investigation.

    PubMed

    Poterba, J M

    1998-10-01

    "This paper investigates the association between population age structure, particularly the share of the population in the 'prime saving years' 45-60, and the returns on stocks and bonds. The paper is motivated by the claim that the aging of the 'Baby Boom' cohort in the United States is a key factor in explaining the recent rise in asset values. It also addresses the associated claim that asset prices will decline when this large cohort reaches retirement age and begins to reduce its asset holdings. This paper begins by considering household age-asset accumulation profiles. Data from the Survey of Consumer Finances suggest that while cross-sectional age-wealth profiles peak for households in their early 60s, cohort data on the asset ownership of the same households show a much less pronounced peak.... The paper then considers the historical relationship between demographic structure and real returns on Treasury bills, long-term government bonds, and corporate stock. The results do not suggest any robust relationship between demographic structure and asset returns.... The paper concludes by discussing factors such as international capital flows and forward-looking behavior on the part of market participants that could weaken the relationship between age structure and asset returns in a single nation."

  18. Hygrothermal aging effects on buried molecular structures at epoxy interfaces.

    PubMed

    Myers, John N; Zhang, Chi; Lee, Kang-Wook; Williamson, Jaimal; Chen, Zhan

    2014-01-14

    Interfacial properties such as adhesion are determined by interfacial molecular structures. Adhesive interfaces in microelectronic packages that include organic polymers such as epoxy are susceptible to delamination during accelerated stress testing. Infrared-visible sum frequency generation vibrational spectroscopy (SFG) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) were used to study molecular structures at buried epoxy interfaces during hygrothermal aging to relate molecular structural changes at buried interfaces to decreases in macroscopic adhesion strength. SFG peaks associated with strongly hydrogen bonded water were detected at hydrophilic epoxy interfaces. Ordered interfacial water was also correlated to large decreases in interfacial adhesion strength that occurred as a result of hygrothermal aging, which suggests that water diffused to the interface and replaced original hydrogen bond networks. No water peaks were observed at hydrophobic epoxy interfaces, which was correlated with a much smaller decrease in adhesion strength from the same aging process. ATR-FTIR water signals observed in the epoxy bulk were mainly contributed by relatively weakly hydrogen bonded water molecules, which suggests that the bulk and interfacial water structure was different. Changes in interfacial methyl structures were observed regardless of the interfacial hydrophobicity which could be due to water acting as a plasticizer that restructured both the bulk and interfacial molecular structure. This research demonstrates that SFG studies of molecular structural changes at buried epoxy interfaces during hygrothermal aging can contribute to the understanding of moisture-induced failure mechanisms in electronic packages that contain organic adhesives.

  19. Structural and Functional Changes With the Aging Kidney.

    PubMed

    Denic, Aleksandar; Glassock, Richard J; Rule, Andrew D

    2016-01-01

    Senescence or normal physiologic aging portrays the expected age-related changes in the kidney as compared to a disease that occurs in some but not all individuals. The microanatomical structural changes of the kidney with older age include a decreased number of functional glomeruli from an increased prevalence of nephrosclerosis (arteriosclerosis, glomerulosclerosis, and tubular atrophy with interstitial fibrosis), and to some extent, compensatory hypertrophy of remaining nephrons. Among the macroanatomical structural changes, older age associates with smaller cortical volume, larger medullary volume until middle age, and larger and more numerous kidney cysts. Among carefully screened healthy kidney donors, glomerular filtration rate (GFR) declines at a rate of 6.3 mL/min/1.73 m(2) per decade. There is reason to be concerned that the elderly are being misdiagnosed with CKD. Besides this expected kidney function decline, the lowest risk of mortality is at a GFR of ≥75 mL/min/1.73 m(2) for age <55 years but at a lower GFR of 45 to 104 mL/min/1.73 m(2) for age ≥65 years. Changes with normal aging are still of clinical significance. The elderly have less kidney functional reserve when they do actually develop CKD, and they are at higher risk for acute kidney injury.

  20. Aging Effects on Regional Brain Structural Changes in Schizophrenia

    PubMed Central

    Nenadić, Igor; Sauer, Heinrich; Smesny, Stefan; Gaser, Christian

    2012-01-01

    Background: Although mostly conceptualized as a neurodevelopmental disorder, there is an increasing interest in progressive changes of cognitive deficits and brain structure and function in schizophrenia across the life span. Methods: In this study, we investigated age-related changes in regional gray matter using voxel-based morphometry in a sample of 99 patients (age range 18–65 years) with Diagnostic and Statistical Manual of Mental Disorders-IV schizophrenia and 113 healthy controls (age range 19–59 years) using a cross-sectional design. Results: We found steeper age-related decline in gray matter in patients in a cluster comprising the left superior temporal cortex and adjacent inferior parietal lobule. We then divided the schizophrenia sample in 3 subgroups based on a 3-factor model of psychopathology ratings. Age-related changes were markedly different in each of the 3 subgroups (compared with healthy controls). While patients with predominantly paranoid symptoms showed stronger age-related progression in the left superior temporal cortex and right inferior frontal gyrus, those of the disorganized subgroup had stronger gray matter loss in the left lateral cerebellum, while the predominantly negative subgroup showed minor effects in the left superior temporal gyrus. Conclusions: Our findings show that differences in brain structural changes associated with aging diverge between schizophrenia patients and healthy subjects and that different subgroups within a patient sample might be at higher risk of age-related regional gray matter loss. PMID:21296908

  1. Contributions of Aging to the Fatigue Crack Growth Resistance of Human Dentin

    PubMed Central

    Ivancik, Juliana; Majd, Hessam; Bajaj, Devendra; Romberg, Elaine; Arola, Dwayne

    2012-01-01

    An evaluation of the fatigue crack resistance of human dentin was conducted to identify the degree of degradation that arises with aging and the dependency on tubule orientation. Fatigue crack growth was achieved in specimens of coronal dentin through application of Mode I cyclic loading and over clinically relevant lengths (0 ≤ a ≤ 2 mm). The study considered two directions of cyclic crack growth in which the crack was either in-plane (0°) or perpendicular (90°) to the dentin tubules. Results showed that regardless of tubule orientation, aging of dentin is accompanied by a significant reduction in the resistance to the initiation of fatigue crack growth, as well as a significant increase in the rate of incremental extension. Perpendicular to the tubules, the fatigue crack exponent increased significantly (from m=14.2±1.5 to 24.1±5.0), suggesting an increase in brittleness of the tissue with age. For cracks extending in plane with the tubules, the fatigue crack growth exponent does not change significantly with patient age (from m=25.4±3.03 to 22.9±5.3), but there is a significant increase in the incremental crack growth rate. Regardless of age, coronal dentin exhibits the lowest resistance to fatigue crack growth perpendicular to the tubules. While there are changes in the cyclic crack growth rate and mechanisms of cyclic extension with aging, this tissue maintains its anisotropy. PMID:22484693

  2. Slow growth of Empetrum nigrum in industrial barrens: combined effect of pollution and age of extant plants.

    PubMed

    Zverev, Vitali E; Zvereva, Elena L; Kozlov, Mikhail V

    2008-11-01

    We studied the impact of industrial pollution on population demography (age structure), growth and reproduction of crowberry, Empetrum nigrum L. Crowberry growing in severely polluted sites near non-ferrous smelters (at Harjavalta, Monchegorsk and Nikel) was on average twice as old as in unpolluted habitats, as indicated by the number of annual rings at root collar. Shoot length decreased both with plant ageing and due to pollution impact, while neither the proportion of generative plants nor berry production was affected by pollution or plant age. Our results suggest that death of the extant individuals of E. nigrum near the non-ferrous smelters is to a large extent explained by age-related damage of the main stem accelerated by pollution. Since vegetative propagation, seed germination and seedling establishment are hampered by soil toxicity, E. nigrum populations near the smelters continue to decline with ageing in spite of the gradual decline of emissions.

  3. [Aging and retrieval-induced forgetting of associatively structured lists].

    PubMed

    Matsuda, Takashi; Matsukawa, Junko

    2010-12-01

    Research on retrieval-induced forgetting has shown that remembering can cause forgetting of related information. This study examined whether such forgetting occurred for associatively structured lists and if aging influenced such forgetting. We compared retrieval-induced forgetting during a free recall test by using Deese/Roediger-McDermott (DRM) lists with an associative structure as the stimulus. Two age groups of young and old adult participants were tested. The results indicated that both age groups showed the same degree of retrieval-induced forgetting of the lists. These results suggest that the association between items causes retrieval-induced forgetting and that the inhibitory function of the association in retrieval-induced forgetting does not decline with age.

  4. Thalamic structures and associated cognitive functions: Relations with age and aging

    PubMed Central

    Fama, Rosemary; Sullivan, Edith V.

    2015-01-01

    The thalamus, with its cortical, subcortical, and cerebellar connections, is a critical node in networks supporting cognitive functions known to decline in normal aging, including component processes of memory and executive functions of attention and information processing. The macrostructure, microstructure, and neural connectivity of the thalamus changes across the adult lifespan. Structural and functional magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) have demonstrated, regional thalamic volume shrinkage and microstructural degradation, with anterior regions generally more compromised than posterior regions. The integrity of selective thalamic nuclei and projections decline with advancing age, particularly those in thalamofrontal, thalamoparietal, and thalamolimbic networks. This review presents studies that assess the relations between age and aging and the structure, function, and connectivity of the thalamus and associated neural networks and focuses on their relations with processes of attention, speed of information processing, and working and episodic memory. PMID:25862940

  5. Report on aging of nuclear power plant reinforced concrete structures

    SciTech Connect

    Naus, D.J.; Oland, C.B.; Ellingwood, B.R.

    1996-03-01

    The Structural Aging Program provides the US Nuclear Regulatory Commission with potential structural safety issues and acceptance criteria for use in continued service assessments of nuclear power plant safety-related concrete structures. The program was organized under four task areas: Program Management, Materials Property Data Base, Structural Component Assessment/Repair Technology, and Quantitative Methodology for Continued Service Determinations. Under these tasks, over 90 papers and reports were prepared addressing pertinent aspects associated with aging management of nuclear power plant reinforced concrete structures. Contained in this report is a summary of program results in the form of information related to longevity of nuclear power plant reinforced concrete structures, a Structural Materials Information Center presenting data and information on the time variation of concrete materials under the influence of environmental stressors and aging factors, in-service inspection and condition assessments techniques, repair materials and methods, evaluation of nuclear power plant reinforced concrete structures, and a reliability-based methodology for current and future condition assessments. Recommendations for future activities are also provided. 308 refs., 61 figs., 50 tabs.

  6. Age, growth, and size of Lake Superior Pygmy Whitefish (Prosopium coulterii)

    USGS Publications Warehouse

    Stewart, Taylor; Derek Ogle,; Gorman, Owen T.; Vinson, Mark

    2016-01-01

    Pygmy Whitefish (Prosopium coulterii) are a small, glacial relict species with a disjunct distribution in North America and Siberia. In 2013 we collected Pygmy Whitefish at 28 stations from throughout Lake Superior. Total length was recorded for all fish and weight and sex were recorded and scales and otoliths were collected from a subsample. We compared the precision of estimated ages between readers and between scales and otoliths, estimated von Bertalanffy growth parameters for male and female Pygmy Whitefish, and reported the first weight-length relationship for Pygmy Whitefish. Age estimates between scales and otoliths differed significantly with otolith ages significantly greater for most ages after age-3. Maximum otolith age was nine for females and seven for males, which is older than previously reported for Pygmy Whitefish from Lake Superior. Growth was initially fast but slowed considerably after age-3 for males and age-4 for females, falling to 3–4 mm per year at maximum estimated ages. Females were longer than males after age-3. Our results suggest the size, age, and growth of Pygmy Whitefish in Lake Superior have not changed appreciably since 1953.

  7. Exploring the vertical age structure of the Galactic disc

    NASA Astrophysics Data System (ADS)

    Casagrande, Luca

    While in external or high-redshift galaxies we can only measure integrated stellar properties at best, the Milky Way offers us the unique opportunity to study its individual baryonic components, including stars. We use oscillations measured in red giant stars by the Kepler satellite to derive stellar ages and explore the vertical age structure across few kpc of the Milky Way disc. We find that old stars dominate at increasing Galactic heights, whereas closer to the plane a rich zoology of ages exists. The age distribution of stars shows a smooth distribution over the last 10 Gyr, which together with a flat age-metallicity relation is consistent with a quiescent evolution for the Milky Way disc since a redshift of about two.

  8. Comparative age and growth of common snook Centropomus undecimalis (Pisces: Centropomidae) from coastal and riverine areas in Southern Mexico.

    PubMed

    Perera-Garcia, Martha A; Mendoza-Carranza, Manuel; Contreras-Sánchez, Wilfrido; Ferrara, Allyse; Huerta-Ortiz, Maricela; Hernández-Gómez, Raúl E

    2013-06-01

    Common snook Centropomus unidecimalis is an important commercial and fishery species in Southern Mexico, however the high exploitation rates have resulted in a strong reduction of its abundances. Since, the information about its population structure is scarce, the objective of the present research was to determine and compare the age structure in four important fishery sites. For this, age and growth of common snook were determined from specimens collected monthly, from July 2006 to March 2008, from two coastal (Barra Bosque and Barra San Pedro) and two riverine (San Pedro and Tres Brazos) commercial fishery sites in Tabasco, Mexico. Age was determined using sectioned saggitae otoliths and data analyzed by von Bertalanffy and Levenberg-Marquardt among others. Estimated ages ranged from 2 to 17 years. Monthly patterns of marginal increment formation and the percentage of otoliths with opaque rings on the outer edge demonstrated that a single annulus was formed each year. The von Bertalanffy parameters were calculated for males and females using linear adjustment and the non-linear method of Levenberg-Marquardt. The von Bertalanffy growth equations were FLt = 109.21(1-e-0.2(t+0.57)) for Barra Bosque, FLt = 94.56(1-e-027(t+0.485)) for Barra San Pedro, FLt = 97.15(1-e 0.17(t + 1.32)) for San Pedro and FLt = 83.77(1-e-026(t + 0.49)) for Tres Brazos. According to (Hotelling's T2, p < 0.05) test growth was significantly greater for females than for males. Based on the Chen test, von Bertalanffy growth curves were different among the study sites (RSS, p < 0.05). Based on the observed differences in growth parameters among sampling sites (coastal and riverine environments) future research need to be conducted on migration and population genetics, in order to delineate the stock structure of this population and support management programs.

  9. [Age-related characteristics of structural support for ovarian function].

    PubMed

    Koval'skiĭ, G B

    1984-12-01

    Histoenzymological assay was used to investigate various structures of the ovaries of rats of two groups aged 3-4 and 12-14 months during estral cycle. The activity of 3 beta-, 17 beta- and 20 alpha-steroid dehydrogenases, glucose-6-phosphate dehydrogenase, NAD and NADP-diaphorases, esterase, acid and alkaline phosphatases was studied. It has been shown that transport alterations in the microcirculation including the hematofollicular barrier play, the leading part in age-dependent depression of reproductive and endocrine functions. Ageing rats demonstrated no linkage between endothelial, thecal and granular cells, which points to the injury of the histophysiological mechanisms of the follicular system integration.

  10. Structural and Cultural Factors in Successful Aging Among Older Hispanics

    PubMed Central

    Angel, Ronald J.

    2014-01-01

    Successful or healthful aging are terms that draw attention to life course issues related to individual, physical, and psychologic development and maturation, but they also draw attention to the material basis of successful aging and the social structures that determine one’s place in the social hierarchy. This article focuses on barriers to optimal aging for Hispanics, especially those of Mexican origin, and argues that cultural factors and social class are closely associated. The reduction of health disparities and equity in medical and long-term care requires an understanding of both cultural and material sources of differential health levels. PMID:19065093

  11. Associations between education and brain structure at age 73 years, adjusted for age 11 IQ

    PubMed Central

    Dickie, David Alexander; Ritchie, Stuart J.; Karama, Sherif; Pattie, Alison; Royle, Natalie A.; Corley, Janie; Aribisala, Benjamin S.; Valdés Hernández, Maria; Muñoz Maniega, Susana; Starr, John M.; Bastin, Mark E.; Evans, Alan C.; Wardlaw, Joanna M.; Deary, Ian J.

    2016-01-01

    Objective: To investigate how associations between education and brain structure in older age were affected by adjusting for IQ measured at age 11. Methods: We analyzed years of full-time education and measures from an MRI brain scan at age 73 in 617 community-dwelling adults born in 1936. In addition to average and vertex-wise cortical thickness, we measured total brain atrophy and white matter tract fractional anisotropy. Associations between brain structure and education were tested, covarying for sex and vascular health; a second model also covaried for age 11 IQ. Results: The significant relationship between education and average cortical thickness (β = 0.124, p = 0.004) was reduced by 23% when age 11 IQ was included (β = 0.096, p = 0.041). Initial associations between longer education and greater vertex-wise cortical thickness were significant in bilateral temporal, medial-frontal, parietal, sensory, and motor cortices. Accounting for childhood intelligence reduced the number of significant vertices by >90%; only bilateral anterior temporal associations remained. Neither education nor age 11 IQ was significantly associated with total brain atrophy or tract-averaged fractional anisotropy. Conclusions: The association between years of education and brain structure ≈60 years later was restricted to cortical thickness in this sample; however, the previously reported associations between longer education and a thicker cortex are likely to be overestimates in terms of both magnitude and distribution. This finding has implications for understanding, and possibly ameliorating, life-course brain health. PMID:27664981

  12. Mathematical modelling of the growth of human fetus anatomical structures.

    PubMed

    Dudek, Krzysztof; Kędzia, Wojciech; Kędzia, Emilia; Kędzia, Alicja; Derkowski, Wojciech

    2016-07-08

    The goal of this study was to present a procedure that would enable mathematical analysis of the increase of linear sizes of human anatomical structures, estimate mathematical model parameters and evaluate their adequacy. Section material consisted of 67 foetuses-rectus abdominis muscle and 75 foetuses- biceps femoris muscle. The following methods were incorporated to the study: preparation and anthropologic methods, image digital acquisition, Image J computer system measurements and statistical analysis method. We used an anthropologic method based on age determination with the use of crown-rump length-CRL (V-TUB) by Scammon and Calkins. The choice of mathematical function should be based on a real course of the curve presenting growth of anatomical structure linear size Ύ in subsequent weeks t of pregnancy. Size changes can be described with a segmental-linear model or one-function model with accuracy adequate enough for clinical purposes. The interdependence of size-age is described with many functions. However, the following functions are most often considered: linear, polynomial, spline, logarithmic, power, exponential, power-exponential, log-logistic I and II, Gompertz's I and II and von Bertalanffy's function. With the use of the procedures described above, mathematical models parameters were assessed for V-PL (the total length of body) and CRL body length increases, rectus abdominis total length h, its segments hI, hII, hIII, hIV, as well as biceps femoris length and width of long head (LHL and LHW) and of short head (SHL and SHW). The best adjustments to measurement results were observed in the exponential and Gompertz's models.

  13. Physical Growth, Biological Age, and Nutritional Transitions of Adolescents Living at Moderate Altitudes in Peru

    PubMed Central

    Cossio-Bolaños, Marco; Gómez Campos, Rossana; Andruske, Cynthia Lee; Flores, Antonio Viveros; Luarte-Rocha, Cristian; Olivares, Pedro R.; Garcia-Rubio, Javier; de Arruda, Miguel

    2015-01-01

    Background: Peru is experiencing a stage of nutritional transition where the principal characteristics are typical of countries undergoing development. Objectives: The objectives of this study were the following: (a) compare physical growth patterns with an international standard; (b) determine biological age; and (c) analyze the double nutritional burden of adolescents living at a moderate altitude in Peru. Design: Weight, standing height, and sitting height were measured in 551 adolescents of both sexes (12.0 to 17.9 years old) from an urban area of Arequipa, Peru (2328 m). Physical growth was compared with the international standard of the CDC-2000. Biological age was determined by using a non-invasive transversal technique based on years from age at peak height velocity (APHV). Nutritional state was determined by means of weight for age and height for age. Z scores were calculated using international standards from the CDC-2000. Results: Body weight for both sexes was similar to the CDC-2000 international standards. At all ages, the girls’ height (p < 0.05) was below the standards. However, the boys’ height (p < 0.05) was less at ages, 15, 16, and 17. Biological age showed up in girls at age 12.7 years and for boys at 15.2 years. Stunted growth (8.7% boys and 18.0% girls) and over weight (11.3% boys and 8.8% girls) occurred in both groups. A relationship existed in both sexes between the categories of weight for the age and stunted growth by sex. Conclusions: Adolescents living at a moderate altitude exhibited stunted linear growth and biological maturation. Furthermore, adolescents of both sexes showed the presence of the double nutritional burden (stunted growth and excessive weight). PMID:26404334

  14. Growth curve analyses of the relationship between early maternal age and children's mathematics and reading performance.

    PubMed

    Torres, D Diego

    2015-03-01

    Regarding the methods used to examine the early maternal age-child academic outcomes relationship, the extant literature has tended to examine change using statistical analyses that fail to appreciate that individuals vary in their rates of growth. Of the one study I have been able to find that employs a true growth model to estimate this relationship, the authors only controlled for characteristics of the maternal household after family formation; confounding background factors of mothers that might select them into early childbearing, a possible source of bias, were ignored. The authors' findings nonetheless suggested an inverse relationship between early maternal age, i.e., a first birth between the ages of 13 and 17, and Canadian adolescents' mean math performance at age 10. Early maternal age was not related to the linear slope of age. To elucidate whether the early maternal age-child academic outcomes association, treated in a growth context, is consistent with this finding, the present study built on it using US data and explored children's mathematics and reading trajectories from age 5 on. Its unique contribution is that it further explicitly controlled for maternal background factors and employed a three-level growth model with repeated measures of children nested within their mothers. Though the strength of the relationship varied between mean initial academic performance and mean academic growth, results confirmed that early maternal age was negatively related to children's mathematics and reading achievement, net of post-teen first birth child-specific and maternal household factors. Once maternal background factors were included, there was no statistically significant relationship between early maternal age and either children's mean initial mathematics and reading scores or their mean mathematics and reading growth.

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

    USGS Publications Warehouse

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

    2015-01-01

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

  16. Effect of thermal implying during ageing process of nanorods growth on the properties of zinc oxide nanorod arrays

    NASA Astrophysics Data System (ADS)

    Ismail, A. S.; Mamat, M. H.; Malek, M. F.; Abdullah, M. A. R.; Sin, M. D.; Rusop, M.

    2016-07-01

    Undoped and Sn-doped Zinc oxide (ZnO) nanostructures have been fabricated using a simple sol-gel immersion method at 95°C of growth temperature. Thermal sourced by hot plate stirrer was supplied to the solution during ageing process of nanorods growth. The results showed significant decrement in the quality of layer produced after the immersion process where the conductivity and porosity of the samples reduced significantly due to the thermal appliance. The structural properties of the samples have been characterized using field emission scanning electron microscopy (FESEM) electrical properties has been characterized using current voltage (I-V) measurement.

  17. Mind-Reading Ability and Structural Connectivity Changes in Aging

    PubMed Central

    Cabinio, Monia; Rossetto, Federica; Blasi, Valeria; Savazzi, Federica; Castelli, Ilaria; Massaro, Davide; Valle, Annalisa; Nemni, Raffaello; Clerici, Mario; Marchetti, Antonella; Baglio, Francesca

    2015-01-01

    The Mind-Reading ability through the eyes is an important component of the affective Theory of Mind (ToM), which allows people to infer the other’s mental state from the eye gaze. The aim of the present study was to investigate to which extent age-associated structural brain changes impact this ability and to determine if this association is related to executive functions in elderly subjects. For this purpose, Magnetic Resonance Imaging was used to determine both gray matter and white matter (WM) areas associated with aging. The resulting areas have been included in a subsequent correlation analysis to detect the brain regions whose structure was associated with the Mind-Reading ability through the eyes, assessed with the Italian version of the “Reading the Mind in the Eyes” (RME) test, in a sample of 36 healthy subjects ranging from 24 to 79 years of age. The analysis resulted in three important findings: (1) the performance to the RME test is relatively stable across the decades 20–70 (despite a slight decrease of this ability with aging) and independent from executive functions; (2) structural brain imaging demonstrated the involvement of a great number of cortical ToM areas for the execution of the RME test: the bilateral precentral gyrus, the bilateral posterior insula, the left superior temporal gyrus and the left inferior frontal gyrus, which also showed a significant volume decrease with age; (3) an age and task-related decline in WM connectivity on left fronto-temporal portion of the brain. Our results confirm the age-related structural modifications of the brain and show that these changes have an influence on the Mind-Reading ability through the eyes. PMID:26635702

  18. Mind-Reading Ability and Structural Connectivity Changes in Aging.

    PubMed

    Cabinio, Monia; Rossetto, Federica; Blasi, Valeria; Savazzi, Federica; Castelli, Ilaria; Massaro, Davide; Valle, Annalisa; Nemni, Raffaello; Clerici, Mario; Marchetti, Antonella; Baglio, Francesca

    2015-01-01

    The Mind-Reading ability through the eyes is an important component of the affective Theory of Mind (ToM), which allows people to infer the other's mental state from the eye gaze. The aim of the present study was to investigate to which extent age-associated structural brain changes impact this ability and to determine if this association is related to executive functions in elderly subjects. For this purpose, Magnetic Resonance Imaging was used to determine both gray matter and white matter (WM) areas associated with aging. The resulting areas have been included in a subsequent correlation analysis to detect the brain regions whose structure was associated with the Mind-Reading ability through the eyes, assessed with the Italian version of the "Reading the Mind in the Eyes" (RME) test, in a sample of 36 healthy subjects ranging from 24 to 79 years of age. The analysis resulted in three important findings: (1) the performance to the RME test is relatively stable across the decades 20-70 (despite a slight decrease of this ability with aging) and independent from executive functions; (2) structural brain imaging demonstrated the involvement of a great number of cortical ToM areas for the execution of the RME test: the bilateral precentral gyrus, the bilateral posterior insula, the left superior temporal gyrus and the left inferior frontal gyrus, which also showed a significant volume decrease with age; (3) an age and task-related decline in WM connectivity on left fronto-temporal portion of the brain. Our results confirm the age-related structural modifications of the brain and show that these changes have an influence on the Mind-Reading ability through the eyes.

  19. Edge crack growth of thermally aged graphite/polyimide composites

    NASA Technical Reports Server (NTRS)

    Nelson, J. B.

    1984-01-01

    Laminates of Celion 6000/LARC-160 and Celion 6000/PMR-15 graphite/polyimide composite materials were aged in air at temperatures of 202, 232, 260 and 288 C for various times up to 15,000 hours. Three unidirectional specimen types were studied: short beam shear (SBS), flexure, and 153 mm square panels. The interior region of the square panels exhibited little or no property degradation, whereas both laminate materials degraded and cracked preferentially at the specimen edge perpendicular to the fibers. Using a dye penetrant, the specimens were X-rayed and the crack depth measured as a function of time and temperature. A time temperature superposition of the crack data was successfully performed using an Arrhenius form for the shift factor. A direct correlation was found for edge crack depth and SBS strength for the LARC-160 laminates but the correlation for PMR-15 laminates was more complex.

  20. 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

  1. Growth in Reading Achievement of Students with Disabilities, Ages 7 to 17

    ERIC Educational Resources Information Center

    Wei, Xin; Blackorby, Jose; Schiller, Ellen

    2011-01-01

    Using data from the Special Education Elementary Longitudinal Study (SRI International, 2002), this study estimated reading growth trajectories in a nationally representative sample of 3,421 students with disabilities ages 7 to 17 representing 11 federal disability categories. Reading achievement in all disability categories increased with age,…

  2. Age Differences within Secular IQ Trends: An Individual Growth Modeling Approach

    ERIC Educational Resources Information Center

    Kanaya, Tomoe; Ceci, Stephen J.; Scullin, Matthew H.

    2005-01-01

    Age differences within the yo-yo trend in IQ, caused when aging norms that produce inflated scores are replaced with new norms, were examined using longitudinal WISC, WISC-R and WISC-III records of students tested for special education services from 10 school districts. Descriptive and individual growth modeling analyses revealed that while the…

  3. Effect of thermal aging on the fatigue crack growth behavior of cast duplex stainless steels

    NASA Astrophysics Data System (ADS)

    Lü, Xu-ming; Li, Shi-lei; Zhang, Hai-long; Wang, Yan-li; Wang, Xi-tao

    2015-11-01

    The effect of thermal aging on the fatigue crack growth (FCG) behavior of Z3CN20?09M cast duplex stainless steel with low ferrite content was investigated in this study. The crack surfaces and crack growth paths were analyzed to clarify the FCG mechanisms. The microstructure and micromechanical properties before and after thermal aging were also studied. Spinodal decomposition in the aged ferrite phase led to an increase in the hardness and a decrease in the plastic deformation capacity, whereas the hardness and plastic deformation capacity of the austenite phase were almost unchanged after thermal aging. The aged material exhibited a better FCG resistance than the unaged material in the near-threshold regime because of the increased roughness-induced crack closure associated with the tortuous crack path and rougher fracture surface; however, the tendency was reversed in the Paris regime because of the cleavage fracture in the aged ferrite phases.

  4. Age at Weaning and Infant Growth: Primary Analysis and Systematic Review

    PubMed Central

    Vail, Brennan; Prentice, Philippa; Dunger, David B.; Hughes, Ieuan A.; Acerini, Carlo L.; Ong, Ken K.

    2015-01-01

    Objective To test whether earlier age at weaning (age 3-6 months) may promote faster growth during infancy. Study design Weaning at age 3.0-7.0 months was reported by 571 mothers of term singletons in a prospective birth cohort study conducted in Cambridge, UK. Infant weight and length were measured at birth and at age 3 months and 12 months. Anthropometric values were transformed into age- and sex-adjusted z-scores. Three linear regression models were performed, including adjustment for confounders in a stepwise manner. Measurements at age 3 months, before weaning, were used to consider reverse causality. Results Almost three-quarters (72.9%) of infants were weaned before age 6 months. Age at weaning of 3.0-7.0 months was inversely associated with weight and length (but not with body mass index) at 12 months (both P ≤ .01, adjusted for maternal and demographic factors). These associations were attenuated after adjustment for type of milk feeding and weight or length at age 3 months (before weaning). Rapid weight gain between 0 and 3 months predicted subsequent earlier age at weaning (P = .01). Our systematic review identified 2 trials, both reporting null effects of age at weaning on growth, and 15 observational studies, with 10 reporting an inverse association between age at weaning and infant growth and 4 reporting evidence of reverse causality. Conclusion In high-income countries, weaning between 3 and 6 months appears to have a neutral effect on infant growth. Inverse associations are likely related to reverse causality. PMID:26073105

  5. Metatarsal growth during the second trimester: a predictor of gestational age?

    PubMed Central

    DE VASCONCELLOS, HENRIQUE AYRES; FERREIRA, ELIANE

    1998-01-01

    Metatarsal growth was studied in 780 human fetal metatarsal bones, crown-rump length ranging from 120 to 260 mm and gestational age ranging from 14 to 23 wk postconception. Total length, diaphyseal length and diameter were measured and statistical analysis performed. Means and standard deviations for each measurement were calculated at 1 wk intervals. These data were correlated with crown-rump length and gestational age and an equation was constructed in an attempt to predict gestational age. PMID:9758145

  6. Aging and Heterogeneity: Genetics, Social Structure, and Personality.

    ERIC Educational Resources Information Center

    Light, John M.; And Others

    1996-01-01

    Suggests that the heterogeneity of human personality characteristics increases with age. Examines reasons for this phenomenon in terms of individual differentiation, social structure/allocation, and behavioral genetics. Develops a model synthesizing various study designs that prevent variation and covariation errors from occurring in life course…

  7. Parameterization of European perch Perca fluviatilis length-at-age data using stochastic Gompertz growth models.

    PubMed

    Troynikov, V S; Gorfine, H K; Ložys, L; Pūtys, Z; Jakubavičiūtė, E; Day, R W

    2011-12-01

    Three stochastic versions of the Gompertz growth model were used to parameterize total length (L(T) )-at-age data for perch Perca fluviatilis, an important target species for commercial and recreational fishers and a food species for predatory fishes and aquatic birds. Each model addresses growth heterogeneity by incorporating random parameters from a specific positive distribution: Weibull, gamma or log-normal. The modelling outputs for each version of the model provide L(T) distributions for selected ages and percentiles of L(T) at age for both males and females. The results highlight the importance of using a stochastic approach and the logistic-like growth pattern for analysing growth data for P. fluviatilis in Curonian Lagoon (Lithuania). Outputs from this modelling can be extended to a stochastic analysis of fish cohort dynamics, incorporating all length-based biological relationships, and the selectivity-related interactions between fish cohorts and fishing gear.

  8. Accurate estimates of age at maturity from the growth trajectories of fishes and other ectotherms.

    PubMed

    Honsey, Andrew E; Staples, David F; Venturelli, Paul A

    2017-01-01

    Age at maturity (AAM) is a key life history trait that provides insight into ecology, evolution, and population dynamics. However, maturity data can be costly to collect or may not be available. Life history theory suggests that growth is biphasic for many organisms, with a change-point in growth occurring at maturity. If so, then it should be possible to use a biphasic growth model to estimate AAM from growth data. To test this prediction, we used the Lester biphasic growth model in a likelihood profiling framework to estimate AAM from length at age data. We fit our model to simulated growth trajectories to determine minimum data requirements (in terms of sample size, precision in length at age, and the cost to somatic growth of maturity) for accurate AAM estimates. We then applied our method to a large walleye Sander vitreus data set and show that our AAM estimates are in close agreement with conventional estimates when our model fits well. Finally, we highlight the potential of our method by applying it to length at age data for a variety of ectotherms. Our method shows promise as a tool for estimating AAM and other life history traits from contemporary and historical samples.

  9. Degree-day accumulation influences annual variability in growth of age-0 walleye

    USGS Publications Warehouse

    Uphoff, Christopher S.; Schoenebeck, Casey W.; Hoback, W. Wyatt; Koupal, Keith D.; Pope, Kevin L.

    2013-01-01

    The growth of age-0 fishes influences survival, especially in temperate regions where size-dependent over-winter mortality can be substantial. Additional benefits of earlier maturation and greater fecundity may exist for faster growing individuals. This study correlated prey densities, growing-degree days, water-surface elevation, turbidity, and chlorophyll a with age-0 walleye Sander vitreus growth in a south-central Nebraska irrigation reservoir. Growth of age-0 walleye was variable between 2003 and 2011, with mean lengths ranging from 128 to 231 mm by fall (September 30th–October 15th). A set of a priori candidate models were used to assess the relative support of explanatory variables using Akaike's information criterion (AIC). A temperature model using the growing degree-days metric was the best supported model, describing 65% of the variability in annual mean lengths of age-0 walleye. The second and third best supported models included the variables chlorophyll a (r2 = 0.49) and larval freshwater drum density (r2 = 0.45), respectively. There have been mixed results concerning the importance of temperature effects on growth of age-0 walleye. This study supports the hypothesis that temperature is the most important predictor of age-0 walleye growth near the southwestern limits of its natural range.

  10. Grain growth and structural relaxation of nanocrystalline Bi₂Te₃

    SciTech Connect

    Humphry-Baker, Samuel A.; Schuh, Christopher A.

    2014-10-21

    Recovery and grain growth behavior is investigated systematically for the nanocrystalline thermoelectric compound bismuth telluride, synthesized by mechanical alloying. During annealing treatments at elevated temperatures, structural evolution is tracked using x-ray diffraction, electron microscopy and calorimetry. Below a homologous temperature of about 0.6T{sub m}, grain growth occurs slowly with an activation energy of 89 kJ/mol. However above this temperature grain growth becomes more rampant with an activation energy of 242 kJ/mol. The transition is attributed to a shift from a relaxation or recovery process that includes some reordering of the grain boundary structure, to a more conventional diffusionally-limited grain growth process. By extrapolating the measured grain growth and microstrain evolution kinetics, a thermal budget map is constructed, permitting recommendations for improving the thermoelectric properties of nanocrystalline materials processed via a powder route.

  11. Measuring aging rates of mice subjected to caloric restriction and genetic disruption of growth hormone signaling.

    PubMed

    Koopman, Jacob J E; van Heemst, Diana; van Bodegom, David; Bonkowski, Michael S; Sun, Liou Y; Bartke, Andrzej

    2016-03-01

    Caloric restriction and genetic disruption of growth hormone signaling have been shown to counteract aging in mice. The effects of these interventions on aging are examined through age-dependent survival or through the increase in age-dependent mortality rates on a logarithmic scale fitted to the Gompertz model. However, these methods have limitations that impede a fully comprehensive disclosure of these effects. Here we examine the effects of these interventions on murine aging through the increase in age-dependent mortality rates on a linear scale without fitting them to a model like the Gompertz model. Whereas these interventions negligibly and non-consistently affected the aging rates when examined through the age-dependent mortality rates on a logarithmic scale, they caused the aging rates to increase at higher ages and to higher levels when examined through the age-dependent mortality rates on a linear scale. These results add to the debate whether these interventions postpone or slow aging and to the understanding of the mechanisms by which they affect aging. Since different methods yield different results, it is worthwhile to compare their results in future research to obtain further insights into the effects of dietary, genetic, and other interventions on the aging of mice and other species.

  12. Measuring aging rates of mice subjected to caloric restriction and genetic disruption of growth hormone signaling

    PubMed Central

    Koopman, Jacob J.E.; van Heemst, Diana; van Bodegom, David; Bonkowski, Michael S.; Sun, Liou Y.; Bartke, Andrzej

    2016-01-01

    Caloric restriction and genetic disruption of growth hormone signaling have been shown to counteract aging in mice. The effects of these interventions on aging are examined through age-dependent survival or through the increase in age-dependent mortality rates on a logarithmic scale fitted to the Gompertz model. However, these methods have limitations that impede a fully comprehensive disclosure of these effects. Here we examine the effects of these interventions on murine aging through the increase in age-dependent mortality rates on a linear scale without fitting them to a model like the Gompertz model. Whereas these interventions negligibly and non-consistently affected the aging rates when examined through the age-dependent mortality rates on a logarithmic scale, they caused the aging rates to increase at higher ages and to higher levels when examined through the age-dependent mortality rates on a linear scale. These results add to the debate whether these interventions postpone or slow aging and to the understanding of the mechanisms by which they affect aging. Since different methods yield different results, it is worthwhile to compare their results in future research to obtain further insights into the effects of dietary, genetic, and other interventions on the aging of mice and other species. PMID:26959761

  13. Management of aging of nuclear power plant containment structures

    SciTech Connect

    Naus, D.; Oland, C.B.; Ellingwood, B.; Norris, W.E.; Graves, H.L. III

    1998-06-01

    Research addressing aging management of nuclear power plant concrete and steel containment structures is summarized. Accomplishments related to concrete containment structures include formation of a materials` property database; an aging assessment methodology to identify critical structures and degradation factors; guidelines and evaluation criteria for use in condition assessments; and a time-dependent reliability-based methodology for condition assessments and estimations of future performance. Under the steel containments and liners activity, a degradation assessment methodology has been developed, mathematical models that describe time-dependent changes in the containment due to aggressive environmental factors have been identified, and statistical data supporting the use of these models in time-dependent reliability analysis have been summarized.

  14. [Age structure and genetic diversity of Homatula pycnolepis in the Nujiang River basin].

    PubMed

    Yue, Xing-Jian; Liu, Shao-Ping; Liu, Ming-Dian; Duan, Xin-Bin; Wang, Deng-Qiang; Chen, Da-Qing

    2013-08-01

    This study examined the age structure of the Loach, Homatula pycnolepis through the otolith growth rings in 204 individual specimens collected from the Xiaomengtong River of the Nujiang River (Salween River) basin in April, 2008. There were only two different age classes, 1 and 2 years of age-no 3 year olds were detected. The age structure of H. pycnolepis was simple. The complete mitochondrial DNA cytochrome b gene sequences (1140) of 80 individuals from 4 populations collected in the Nujiang River drainage were sequenced and a total of 44 variable sites were found among 4 different haplotypes. The global haplotype diversity (Hd) and nucleotide diversity (Pi) were calculated at 0.7595, 0.0151 respectively, and 0, 0 in each population, indicating a consistent lack of genetic diversity in each small population. There was obvious geographic structure in both the Nujiang River basin (NJB) group, and the Nanding River (NDR) group. The genetic distance between NJB and NDR was calculated at 0.0356, suggesting that genetic divergence resulted from long-term isolation of individual population. Such a simple age structure and a lack of genetic diversity in H. pycnolepis may potentially be due to small populations and locale fishing pressures. Accordingly, the results of this study prompt us to recommend that the NJB, NDR and Lancang River populations should be protected as three different evolutionary significant units or separated management units.

  15. Crystal Structure of Patatin-17 in Complex with Aged and Non-Aged Organophosphorus Compounds

    PubMed Central

    Wijeyesakere, Sanjeeva J.; Richardson, Rudy J.; Stuckey, Jeanne A.

    2014-01-01

    Patatin is a non-specific plant lipase and the eponymous member of a broad class of serine hydrolases termed the patatin-like phospholipase domain containing proteins (PNPLAs). Certain PNPLA family members can be inhibited by organophosphorus (OP) compounds. Currently, no structural data are available on the modes of interaction between the PNPLAs and OP compounds or their native substrates. To this end, we present the crystal structure of patatin-17 (pat17) in its native state as well as following inhibition with methyl arachidonyl fluorophosphonate (MAFP) and inhibition/aging with diisopropylphosphorofluoridate (DFP). The native pat17 structure revealed the existence of two portals (portal1 and portal2) that lead to its active-site chamber. The DFP-inhibited enzyme underwent the aging process with the negatively charged phosphoryl oxygen, resulting from the loss of an isopropyl group, being within hydrogen-binding distance to the oxyanion hole. The MAFP-inhibited pat17 structure showed that MAFP did not age following its interaction with the nucleophilic serine residue (Ser77) of pat17 since its O-methyl group was intact. The MAFP moiety is oriented with its phosphoryl oxygen in close proximity to the oxyanion hole of pat17 and its O-methyl group located farther away from the oxyanion hole of pat17 relative to the DFP-bound state. The orientation of the alkoxy oxygens within the two OP compounds suggests a role for the oxyanion hole in stabilizing the emerging negative charge on the oxygen during the aging reaction. The arachidonic acid side chain of MAFP could be contained within portals 1 or 2. Comparisons of pat17 in the native, inhibited, and aged states showed no significant global conformational changes with respect to their Cα backbones, consistent with observations from other α/β hydrolases such as group VIIA phospholipase A2. PMID:25248161

  16. Aging of Johari-Goldstein Relaxation in Structural Glasses

    NASA Astrophysics Data System (ADS)

    Yardimci, Hasan; Leheny, Robert L.

    2006-03-01

    Using frequency-dependent dielectric susceptibility measurements we characterize the aging in two supercooled liquids, sorbitol and xylitol, below their calorimetric glass transition temperatures, Tg. In addition to the alpha relaxation that tracks the structural dynamics, the susceptibilities of both liquids possess a secondary Johari-Goldstein relaxation at higher frequencies. Following a quench below Tg, the susceptibility slowly approaches equilibrium behavior. For both liquids, features of the Johari-Goldstein relaxation display a dependence on the time since the quench, or aging time, that is very similar to the age dependence of the alpha peak. However, one can not assign a single fictive temperature to both the alpha and Johari-Goldstein relaxations. For example, the peak frequency of the Johari-Goldstein relaxation remains constant during aging for sorbitol while it increases with age for xylitol, inconsistent with a decreasing fictive temperature. This behavior contrasts with that of the high frequency tail of the alpha peak whose shape and position track the aging of the main part of the peak.

  17. Physical growth and bone age of survivors of protein energy malnutrition.

    PubMed Central

    Alvear, J; Artaza, C; Vial, M; Guerrero, S; Muzzo, S

    1986-01-01

    Early postnatal malnutrition produces delay in growth and developmental processes, and children from a low socioeconomical level where undernutrition is prevalent are shorter than those from higher socioeconomic levels. We examined the effects of severe and early protein energy malnutrition on growth and bone maturation. We studied 40 preschool children who had been admitted to hospital in infancy with protein energy malnutrition and 38 children from the same socioeconomic level, paired for age and sex, who had never been malnourished. Growth measurements were made over a period of 4-6 years, and bone age was determined in a subgroup through wrist roentgenograms. Results showed a correlation between protein energy malnutrition, birth weight of infants, and mother's height and head circumference. The group with protein energy malnutrition showed a significant delay in stature after four years, especially the girls (p less than 0.001). Weight:height ratio was reduced in boys compared with controls but not in girls. Both groups showed a delay in bone maturation, but there were no significant differences between them. We found a positive correlation between bone age and arm fat area in control boys and between bone age and height for age in boys with protein energy malnutrition. The finding that rehabilitated children were shorter than the control group but had similar bone age at follow up suggests that genetic or prenatal factors were important in their later poor growth, and this suggestion is supported by their smaller birth size and the smaller size of their mothers. PMID:3083790

  18. Reassessment of spiny dogfish Squalus acanthias age and growth using vertebrae and dorsal-fin spines.

    PubMed

    Bubley, W J; Kneebone, J; Sulikowski, J A; Tsang, P C W

    2012-04-01

    Male and female spiny dogfish Squalus acanthias were collected in the western North Atlantic Ocean in the Gulf of Maine between July 2006 and June 2009. Squalus acanthias ranged from 25 to 102 cm stretch total length and were caught during all months of the year except January. Age estimates derived from banding patterns visible in both the vertebrae and second dorsal-fin spines were compared. Vertebral growth increments were visualized using a modified histological staining technique, which was verified as appropriate for obtaining age estimates. Marginal increment analysis of vertebrae verified the increment periodicity, suggesting annual band deposition. Based on increased precision and accuracy of age estimates, as well as more biologically realistic parameters generated in growth models, the current study found that vertebrae provided a more reliable and accurate means of estimating age in S. acanthias than the second dorsal-fin spine. Age estimates obtained from vertebrae ranged from <1 year-old to 17 years for male and 24 years for female S. acanthias. The two-parameter von Bertalanffy growth model fit to vertebrae-derived age estimates produced parameters of L∞ = 94·23 cm and k = 0·11 for males and L∞ = 100·76 cm and k = 0·12 for females. While these growth parameters differed from those previously reported for S. acanthias in the western North Atlantic Ocean, the causes of such differences were beyond the scope of the current study and remain to be determined.

  19. Growth of Byssochlamys Nivea in Pineapple Juice Under the Effect of Water Activity and Ascospore Age

    PubMed Central

    Zimmermann, M.; Miorelli, S.; Massaguer, P.R.; Aragão, G.M.F.

    2011-01-01

    The study of thermal resistant mould, including Byssochlamys nivea, is of extreme importance since it has been associated with fruit and fruit products. The aim of this work is to analyze the influence of water activity (aw) and ascospore age (I) on the growth of Byssochlamys nivea in pineapple juice. Mold growth was carried out under different conditions of water activity (aw) (0.99, 0.96, 0.95, 0.93, 0.90) and ascospore age (I) (30, 51, 60, 69, 90 days). Growth parameters as length of adaptation phase (λ), maximum specific growth rate (µmax) and maximum diameter reached by the colony (A) were obtained through the fit of the Modified Gompertz model to experimental data (measuring radial colony diameter). Statistica 6.0 was used for statistical analyses (significance level α = 0.05). The results obtained clearly showed that water activity is statistically significant and that it influences all growth parameters, while ascospore age does not have any statistically significant influence on growth parameters. Also, these data showed that by increasing aw from 0.90 to 0.99, the λ value substantially decreased, while µmax and A values rose. The data contributed for the understanding of the behavior of B. nivea in pineapple juice. Therefore, it provided mathematical models that can well predict growth parameters, also helping on microbiological control and products’ shelf life determination. PMID:24031622

  20. Structural technology challenges for evolutionary growth of Space Station Freedom

    NASA Technical Reports Server (NTRS)

    Doiron, Harold H.

    1990-01-01

    A proposed evolutionary growth scenario for Space Station Freedom was defined recently by a NASA task force created to study requirements for a Human Exploration Initiative. The study was an initial response to President Bush's July 20, 1989 proposal to begin a long range program of human exploration of space including a permanently manned lunar base and a manned mission to Mars. This growth scenario evolves Freedom into a critical transportation node to support lunar and Mars missions. The growth scenario begins with the Assembly Complete configuration and adds structure, power, and facilities to support a Lunar Transfer Vehicle (LTV) verification flight. Evolutionary growth continues to support expendable, then reusable LTV operations, and finally, LTV and Mars Transfer Vehicle (MTV) operations. The significant structural growth and additional operations creating new loading conditions will present new technological and structural design challenges in addition to the considerable technology requirements of the baseline Space Station Freedom program. Several structural design and technology issues of the baseline program are reviewed and related technology development required by the growth scenario is identified.

  1. Accelerated Aging Experiments for Prognostics of Damage Growth in Composite Materials

    NASA Technical Reports Server (NTRS)

    Saxena, Abhinav; Goebel, Kai Frank; Larrosa, Cecilia C.; Janapati, Vishnuvardhan; Roy, Surajit; Chang, Fu-Kuo

    2011-01-01

    Composite structures are gaining importance for use in the aerospace industry. Compared to metallic structures their behavior is less well understood. This lack of understanding may pose constraints on their use. One possible way to deal with some of the risks associated with potential failure is to perform in-situ monitoring to detect precursors of failures. Prognostic algorithms can be used to predict impending failures. They require large amounts of training data to build and tune damage model for making useful predictions. One of the key aspects is to get confirmatory feedback from data as damage progresses. These kinds of data are rarely available from actual systems. The next possible resource to collect such data is an accelerated aging platform. To that end this paper describes a fatigue cycling experiment with the goal to stress carbon-carbon composite coupons with various layups. Piezoelectric disc sensors were used to periodically interrogate the system. Analysis showed distinct differences in the signatures of growing failures between data collected at conditions. Periodic X-radiographs were taken to assess the damage ground truth. Results after signal processing showed clear trends of damage growth that were correlated to damage assessed from the X-ray images.

  2. Ageing management of french NPP civil work structures

    NASA Astrophysics Data System (ADS)

    Gallitre, E.; Dauffer, D.

    2011-04-01

    This paper presents EDF practice about concrete structure ageing management, from the mechanisms analysis to the formal procedure which allows the French company to increase 900 MWe NPP lifetime until 40 years; it will also introduce its action plan for 60 years lifetime extension. This practice is based on a methodology which identifies every ageing mechanism; both plants feedback and state of the art are screened and conclusions are drawn up into an "ageing analysis data sheet". That leads at first to a collection of 57 data sheets which give the mechanism identification, the components that are concerned and an analysis grid which is designed to assess the safety risk. This analysis screens the reference documents describing the mechanism, the design lifetime hypotheses, the associated regulation or codification, the feedback experiences, the accessibility, the maintenance actions, the repair possibility and so one. This analysis has to lead to a conclusion about the risk taking into account monitoring and maintenance. If the data sheet conclusion is not clear enough, then a more detailed report is launched. The technical document which is needed, is a formal detailed report which summarizes every theoretical knowledge and monitoring data: its objective is to propose a solution for ageing management: this solution can include more inspections or specific research development, or additional maintenance. After a first stage on the 900 MWe units, only two generic ageing management detailed reports have been needed for the civil engineering part: one about reactor building containment, and one about other structures which focuses on concrete inflating reactions. The second stage consists on deriving this generic analysis (ageing mechanism and detailed reports) to every plant where a complete ageing report is required (one report for all equipments and structures of the plant, but specific for each reactor). This ageing management is a continuous process because the

  3. Nucleation and structural growth of cluster crystals.

    PubMed

    Leitold, Christian; Dellago, Christoph

    2016-08-21

    We study the nucleation of crystalline cluster phases in the generalized exponential model with exponent n = 4. Due to the finite value of this pair potential for zero separation, at high densities the system forms cluster crystals with multiply occupied lattice sites. Here, we investigate the microscopic mechanisms that lead to the formation of cluster crystals from a supercooled liquid in the low-temperature region of the phase diagram. Using molecular dynamics and umbrella sampling, we calculate the free energy as a function of the size of the largest crystalline nucleus in the system, and compare our results with predictions from classical nucleation theory. Employing bond-order parameters based on a Voronoi tessellation to distinguish different crystal structures, we analyze the average composition of crystalline nuclei. We find that even for conditions where a multiply occupied fcc crystal is the thermodynamically stable phase, the nucleation into bcc cluster crystals is strongly preferred. Furthermore, we study the particle mobility in the supercooled liquid and in the cluster crystal. In the cluster crystal, the motion of individual particles is captured by a simple reaction-diffusion model introduced previously to model the kinetics of hydrogen bonds.

  4. Age differences in the perception of hierarchical structure in events.

    PubMed

    Kurby, Christopher A; Zacks, Jeffrey M

    2011-01-01

    Everyday activities break down into parts and subparts, and appreciating this hierarchical structure is an important component of understanding. In two experiments we found age differences in the ability to perceive hierarchical structure in continuous activity. In both experiments, younger and older adults segmented movies of everyday activities into large and small meaningful events. Older adults' segmentation deviated more from group norms than did younger adults' segmentation, and older adults' segmentation was less hierarchically organized than that of younger adults. Older adults performed less well than younger adults on event memory tasks. In some cases, measures of event segmentation discriminated between those older adults with better and worse memory. These results suggest that the hierarchical encoding of ongoing activity declines with age, and that such encoding may be important for memory.

  5. Age Differences in the Perception of Hierarchical Structure in Events

    PubMed Central

    Kurby, Christopher A.; Zacks, Jeffrey M.

    2011-01-01

    Everyday activities break down into parts and subparts, and appreciating this hierarchical structure is an important component of understanding. In two experiments we found age differences in the ability to perceive hierarchical structure in continuous activity. In both experiments, younger and older adults segmented movies of everyday activities into large and small meaningful events. Older adults’ segmentation deviated more from group norms than did younger adults’ segmentation, and older adults’ segmentation was less hierarchically organized than that of younger adults. Older adults performed less well than younger adults on event memory tasks. In some cases, measures of event segmentation discriminated between those older adults with better and worse memory. These results suggest that the hierarchical encoding of ongoing activity declines with age, and that such encoding may be important for memory. PMID:21264613

  6. Development of acoustography for NDE of aging structures

    NASA Astrophysics Data System (ADS)

    Sandhu, Jaswinder S.; Wang, Honghui; Popek, Witold J.; Sincebaugh, Patrick J.

    2001-07-01

    Military and commercial aircraft structures are being fielded well beyond their designed life cycle, resulting in escalating maintenance costs. The principle driver behind these costs is the need to nondestructively interrogate large areas to detect and quantify anomalies such as corrosion, cracks, and delaminations. Manual ultrasonic techniques are routinely applied to inspect aircraft structures, but these techniques are time consuming, laborious, and are prone to errors such as operator fatigue and subjectivity. Automated ultrasonic systems require costly, complex scanning systems that are often difficult to adapt to complex shaped structures. Acoustography can provide full-field ultrasonic images in near real-time, making it a suitable method for high-speed, wide area inspection applications. This paper will report on progress being made toward developing acoustography for NDE of aging aircraft structures.

  7. Influence of beaver activity on summer growth and condition of age-2 Atlantic salmon parr

    USGS Publications Warehouse

    Sigourney, D.B.; Letcher, B.H.; Cunjak, R.A.

    2006-01-01

    The activity of beavers Castor canadensis in freshwater environments can have considerable localized impacts on the physical and biological components of riparian ecosystems. By changing the habitat of a stream, beaver dams can cause spatial variation in growth opportunity that may have direct consequences for the growth of resident fish. In a small stream in eastern Canada, we studied the effects of an ephemeral beaver pond on the growth and maturity of age-2 Atlantic salmon Salmo salar parr tagged with passive integrated transponder tags. Water temperature remained relatively uniform throughout the study site. We found very little movement of recaptured fish in the study site. Fish that were recaptured in the beaver pond displayed faster summer growth rates in both length and mass than fish that were recaptured immediately above or below the pond. We also found that parr in the pond maintained relatively high condition factors, whereas fish above and below the pond appeared to decrease in condition factor throughout the summer. In addition to growth, the maturation rates of age-2 males were higher above the dam than below. This study demonstrates the effect a beaver dam can have on individual growth rates. By influencing growth during sensitive periods, the beaver pond may also influence individual life history pathways. This information could be an important component in ecosystem models that predict the effect of beaver population dynamics on the growth of individual salmonids at the landscape scale. ?? Copyright by the American Fisheries Society 2006.

  8. Postnatal growth and development in the preterm and small for gestational age infant.

    PubMed

    Cooke, Richard J

    2010-01-01

    A clear relationship exists between undernutrition, poorer growth and poor development in term and preterm infants. However, preterm infants are at greater risk than term infants. Undernutrition is more common and 'programmed' growth rates are almost six times faster. Thus, even short periods of nutritional deprivation may have significant effects. Recent advances have led to an improvement in early growth but very low birthweight infants remain small for gestational age at hospital discharge. Studies suggest that a 'window of opportunity' exists after hospital discharge, in that better growth between discharge and 2-3 months corrected age is paralleled by better development, and poorer growth is associated with poorer development. However, interventions aimed at improving growth and development have yielded varying results. This may partly be related to differences in study design as well as the composition of the nutrient-enriched formulas. Irrespective, one point is concerning, i.e. infant boys appear to be at a developmental disadvantage when fed a term infant formula after discharge. A single study has also suggested that dietary intervention can improve brain growth in term and preterm infants with perinatal brain injury. However, concern has been expressed about rapid 'catch-up' growth in preterm infants and the development of insulin resistance and visceral adiposity. Data from our group do not support the idea of increased or altered adiposity in preterm infants fed a nutrient-enriched formula after hospital discharge.

  9. Growth response of weanling rats to heated, aged, fractionated, and chemically treated yogurts.

    PubMed

    Hargrove, R E; Alford, J A

    1980-07-01

    Significance of viable cultures in yogurt at time of ingestion on rate of growth of weaning rats was determined. Fresh yogurts were compared with those in which cultures were treated with heat, hydrogen peroxide, and ethylene oxide. They also were aged and freeze-dried. Fractions of yogurt prepared by ultrafiltration were recombined to determine which fraction gave the highest rate of gain in weight. Cultures were inactivated and growth in rats was depressed when yogurt was heated at 60 C and above for 2 min. Hydrogen peroxide reduced the viable yogurt count and rate of gain but not feed consumption. Yogurts treated with ethylene oxide were toxic. Aging did not effect culture viability or feed efficiency, but growth response was reduced. Fractionation of yogurt into components of high and low molecular weight and recombinations with control milk fractions indicated that the growth stimulant remained in the component of high molecular weight.

  10. Creep crack growth behavior of several structural alloys

    NASA Astrophysics Data System (ADS)

    Sadananda, K.; Shahinian, P.

    1983-07-01

    Creep crack growth behavior of several high temperature alloys, Inconel 600, Inconel 625, Inconel X-750, Hastelloy X, Nimonic PE-16, Incoloy 800, and Haynes 25 (HS-25) was examined at 540, 650, 760, and 870 °C. Crack growth rates were analyzed in terms of both linear elastic stress intensity factor and J*-integral parameter. Among the alloys Inconel 600 and Hastelloy X did not show any observable crack growth. Instead, they deformed at a rapid rate resulting in severe blunting of the crack tip. The other alloys, Inconel 625, Inconel X-750, Incoloy 800, HS-25, and PE-16 showed crack growth at one or two temperatures and deformed continuously at other temperatures. Crack growth rates of the above alloys in terms ofJ* parameter were compared with the growth rates of other alloys published in the literature. Alloys such as Inconel X-750, Alloy 718, and IN-100 show very high growth rates as a result of their sensitivity to an air environment. Based on detailed fracture surface analysis, it is proposed that creep crack growth occurs by the nucleation and growth of wedge-type cracks at triple point junctions due to grain boundary sliding or by the formation and growth of cavities at the boundaries. Crack growth in the above alloys occurs only in some critical range of strain rates or temperatures. Since the service conditions for these alloys usually fall within this critical range, knowledge and understanding of creep crack growth behavior of the structural alloys are important.

  11. The Umm Al Binni Structure and Bronze Age Catastrophes

    NASA Astrophysics Data System (ADS)

    Hamacher, Duane W.

    Archaeological excavations of sites dating from 2200 BCE and 1200 BCE in the Middle East, Asia Minor, and southeast Europe provide evidence that a large scale disaster affected Bronze Age civilizations. There are numerous debates as to whether this was caused by warfare, a large-scale natural disaster, or some other factor. In 2001, Sharad Master used satellite images to discover a possible Holocene impact structure in the Al 'Amarah marshes of southern Iraq, known as Umm al Binni lake. With an estimated age of < 5000 years and a diameter of ~3.4 km, this structure may help explain this disaster. Using numerical models and scaling equations for a cosmic impact, I show that although destructive forces would have damaged Sumerian cities within a few hundred km of the coast, it is unlikely that this single impact would have caused the large-scale destruction seen over the larger region. The impact origin of the structure is unconfirmed and any connection to Bronze Age catastrophes remains speculative. Errata: Table 4 provides a list of impact sites, three of which are associated with nickel-iron impactors and therefore cannot be from a "fragmented comet".

  12. Growth hormone receptor signaling is dispensable for HSC function and aging

    PubMed Central

    Stewart, Morag H.; Gutierrez-Martinez, Paula; Beerman, Isabel; Garrison, Brian; Gallagher, Emily J.; LeRoith, Derek

    2014-01-01

    Growth hormone receptor (Ghr) signaling is important in a wide variety of cellular processes including aging; however, the role of Ghr signaling in hematopoietic stem cell (HSC) biology remains unexplored. Within the hematopoietic system, Ghr is expressed in a highly HSC-specific manner and is significantly upregulated during aging. Exposure of young and old HSCs to recombinant growth hormone ex vivo led to diminished short-term reconstitution and restored B-cell output from old HSCs. Hematopoietic-specific genetic deletion of Ghr neither impacted steady-state hematopoiesis nor serial transplantation potential. Repeat challenge with 5-fluorouracil showed that Ghr was dispensable for HSC activation and homeostatic recovery in vivo and, after challenge, Ghr-deficient HSCs functioned normally through serial transplantation. Although exogenous Gh induces age-dependent HSC effects, these results indicate that Ghr signaling appears largely dispensable for HSC function and aging. PMID:25274507

  13. Decreased growth rate of P. falciparum blood stage parasitemia with age in a holoendemic population.

    PubMed

    Pinkevych, Mykola; Petravic, Janka; Chelimo, Kiprotich; Vulule, John; Kazura, James W; Moormann, Ann M; Davenport, Miles P

    2014-04-01

    In malaria holoendemic settings, decreased parasitemia and clinical disease is associated with age and cumulative exposure. The relative contribution of acquired immunity against various stages of the parasite life cycle is not well understood. In particular, it is not known whether changes in infection dynamics can be best explained by decreasing rates of infection, or by decreased growth rates of parasites in blood. Here, we analyze the dynamics of Plasmodium falciparum infection after treatment in a cohort of 197 healthy study participants of different ages. We use both polymerase chain reaction (PCR) and microscopy detection of parasitemia in order to understand parasite growth rates and infection rates over time. The more sensitive PCR assay detects parasites earlier than microscopy, and demonstrates a higher overall prevalence of infection than microscopy alone. The delay between PCR and microscopy detection is significantly longer in adults compared with children, consistent with slower parasite growth with age. We estimated the parasite multiplication rate from delay to PCR and microscopy detections of parasitemia. We find that both the delay between PCR and microscopy infection as well as the differing reinfection dynamics in different age groups are best explained by a slowing of parasite growth with age.

  14. On the Importance of Aging to the Crack Growth Resistance of Human Enamel

    PubMed Central

    Yahyazadehfar, Mobin; Zhang, Dongsheng; Arola, Dwayne

    2016-01-01

    With improvements in oral health and an overall increase in quality of life, the percentage of fully or largely dentate seniors is increasing. Understanding the effects of aging on the mechanical properties of teeth is essential to the maintenance of lifelong oral health. In this investigation the effects of aging on the fracture toughness of human enamel were evaluated from incremental crack growth experiments performed on tissue of donor teeth representing “young” (17≤ age ≤ 25) and “old” (age ≥ 55) age groups. Results showed that the old enamel exhibited significantly lower resistance to fracture than that of the young tissue in two orthogonal directions of crack growth. For crack growth transverse to the enamel rods, the fracture toughness of the old enamel (0.37±0.15 MPa•m0.5) was nearly 70% lower than that of tissue from the young teeth (1.23±0.20 MPa•m0.5). Based on results from a mechanistic analysis of crack growth, the reduction in fracture resistance is attributed to a decreased in the degree of extrinsic toughening. The practice of restorative dentistry should account for these changes in tooth tissues in the treatment of senior patients. PMID:26747980

  15. Growth Mechanism of Pumpkin-Shaped Vaterite Hierarchical Structures

    NASA Astrophysics Data System (ADS)

    Ma, Guobin; Xu, Yifei; Wang, Mu

    2015-03-01

    CaCO3-based biominerals possess sophisticated hierarchical structures and promising mechanical properties. Recent researches imply that vaterite may play an important role in formation of CaCO3-based biominerals. However, as a less common polymorph of CaCO3, the growth mechanism of vaterite remains not very clear. Here we report the growth of a pumpkin-shaped vaterite hierarchical structure with a six-fold symmetrical axis and lamellar microstructure. We demonstrate that the growth is controlled by supersaturation and the intrinsic crystallographic anisotropy of vaterite. For the scenario of high supersaturation, the nucleation rate is higher than the lateral extension rate, favoring the ``double-leaf'' spherulitic growth. Meanwhile, nucleation occurs preferentially in < 11 2 0 > as determined by the crystalline structure of vaterite, modulating the grown products with a hexagonal symmetry. The results are beneficial for an in-depth understanding of the biomineralization of CaCO3. The growth mechanism may also be applicable to interpret the formation of similar hierarchical structures of other materials. The authors gratefully acknowledge the financial support from National Science Foundation of China (Grant Nos. 51172104 and 50972057) and National Key Basic Research Program of China (Grant No. 2010CB630705).

  16. Growth charts for Down's syndrome from birth to 18 years of age

    PubMed Central

    Myrelid, A; Gustafsson, J; Ollars, B; Anneren, G

    2002-01-01

    Background: Growth in children with Down's syndrome (DS) differs markedly from that of normal children. The use of DS specific growth charts is important for diagnosis of associated diseases, such as coeliac disease and hypothyroidism, which may further impair growth. Aims: To present Swedish DS specific growth charts. Methods: The growth charts are based on a combination of longitudinal and cross sectional data from 4832 examinations of 354 individuals with DS (203 males, 151 females), born in 1970–97. Results: Mean birth length was 48 cm in both sexes. Final height, 161.5 cm for males and 147.5 cm for females, was reached at relatively young ages, 16 and 15 years, respectively. Mean birth weight was 3.0 kg for boys and 2.9 kg for girls. A body mass index (BMI) >25 kg/m2 at 18 years of age was observed in 31% of the males and 36% of the females. Head growth was impaired, resulting in a SDS for head circumference of -0.5 (Swedish standard) at birth decreasing to -2.0 at 4 years of age. Conclusion: Despite growth retardation the difference in height between the sexes is the same as that found in healthy individuals. Even though puberty appears somewhat early, the charts show that DS individuals have a decreased pubertal growth rate. Our growth charts show that European boys with DS are taller than corresponding American boys, whereas European girls with DS, although being lighter, have similar height to corresponding American girls. PMID:12138052

  17. Effects of recruitment, growth, and exploitation on walleye population size structure in northern Wisconsin lakes

    USGS Publications Warehouse

    Hansen, Michael J.; Nate, Nancy A.

    2014-01-01

    We evaluated the dynamics of walleye Sander vitreus population size structure, as indexed by the proportional size distribution (PSD) of quality-length fish, in Escanaba Lake during 1967–2003 and in 204 other lakes in northern Wisconsin during 1990–2011. We estimated PSD from angler-caught walleyes in Escanaba Lake and from spring electrofishing in 204 other lakes, and then related PSD to annual estimates of recruitment to age-3, length at age 3, and annual angling exploitation rate. In Escanaba Lake during 1967–2003, annual estimates of PSD were highly dynamic, growth (positively) explained 35% of PSD variation, recruitment explained only 3% of PSD variation, and exploitation explained only 7% of PSD variation. In 204 other northern Wisconsin lakes during 1990–2011, PSD varied widely among lakes, recruitment (negatively) explained 29% of PSD variation, growth (positively) explained 21% of PSD variation, and exploitation explained only 4% of PSD variation. We conclude that population size structure was most strongly driven by recruitment and growth, rather than exploitation, in northern Wisconsin walleye populations. Studies of other species over wide spatial and temporal ranges of recruitment, growth, and mortality are needed to determine which dynamic rate most strongly influences population size structure of other species. Our findings indicate a need to be cautious about assuming exploitation is a strong driver of walleye population size structure.

  18. Age determination in manatees using growth-layer-group counts in bone

    USGS Publications Warehouse

    Marmontel, M.; O'Shea, T.J.; Kochman, H.I.; Humphrey, S.R.

    1996-01-01

    Growth layers were observed in histological preparations of bones of known-age, known minimum-age, and tetracycline-marked free-ranging and captive Florida manatees (Trichechus manatus latirostris), substantiating earlier preliminary findings of other studies. Detailed analysis of 17 new case histories showed that growth-layer group (GLG) counts in the periotic bone were consistent with known age, or time since tetracycline administration, but were less reliable in other bones. GLG counts were also made in periotic bones of 1,196 Florida manatees of unknown age found dead from 1974 through 1991. These counts were conducted in order to assess variability and to determine relationships among estimated age, size, sex, and degree of bone resorption. Resorption can interfere with accuracy of GLG counts. This effect does not occur until ages greater than about 15 yr and body lengths greater than 300 cm are attained. GLGs were also observed in periotic bones of Antillean manatees (Trichechus manatus manatus) but were not validated against known-age specimens. Use of GLG counts in the periotic bone is suitable for application to studies of population dynamics and other age-related aspects of manatee biology.

  19. The effect of growth rate, diameter and impurity concentration on structure in Czochralski silicon crystal growth

    NASA Technical Reports Server (NTRS)

    Digges, T. G., Jr.; Shima, R.

    1980-01-01

    It is demonstrated that maximum growth rates of up to 80% of the theoretical limit can be attained in Czochralski-grown silicon crystals while maintaining single crystal structure. Attaining the other 20% increase is dependent on design changes in the grower, to reduce the temperature gradient in the liquid while increasing the gradient in the solid. The conclusions of Hopkins et al. (1977) on the effect of diameter on the breakdown of structure at fast growth rates are substantiated. Copper was utilized as the test impurity. At large diameters (greater than 7.5 cm), concentrations of greater than 1 ppm copper were attained in the solid (45,000 ppm in the liquid) without breakdown at maximum growth speeds. For smaller diameter crystals, the sensitivity of impurities is much more apparent. For solar cell applications, impurities will limit cell performance before they cause crystal breakdown for fast growth rates of large diameter crystals.

  20. Network structure impacts global commodity trade growth and resilience

    PubMed Central

    Rovenskaya, Elena; Fath, Brian D.

    2017-01-01

    Global commodity trade networks are critical to our collective sustainable development. Their increasing interconnectedness pose two practical questions: (i) Do the current network configurations support their further growth? (ii) How resilient are these networks to economic shocks? We analyze the data of global commodity trade flows from 1996 to 2012 to evaluate the relationship between structural properties of the global commodity trade networks and (a) their dynamic growth, as well as (b) the resilience of their growth with respect to the 2009 global economic shock. Specifically, we explore the role of network efficiency and redundancy using the information theory-based network flow analysis. We find that, while network efficiency is positively correlated with growth, highly efficient systems appear to be less resilient, losing more and gaining less growth following an economic shock. While all examined networks are rather redundant, we find that network redundancy does not hinder their growth. Moreover, systems exhibiting higher levels of redundancy lose less and gain more growth following an economic shock. We suggest that a strategy to support making global trade networks more efficient via, e.g., preferential trade agreements and higher specialization, can promote their further growth; while a strategy to increase the global trade networks’ redundancy via e.g., more abundant free-trade agreements, can improve their resilience to global economic shocks. PMID:28207790

  1. Network structure impacts global commodity trade growth and resilience.

    PubMed

    Kharrazi, Ali; Rovenskaya, Elena; Fath, Brian D

    2017-01-01

    Global commodity trade networks are critical to our collective sustainable development. Their increasing interconnectedness pose two practical questions: (i) Do the current network configurations support their further growth? (ii) How resilient are these networks to economic shocks? We analyze the data of global commodity trade flows from 1996 to 2012 to evaluate the relationship between structural properties of the global commodity trade networks and (a) their dynamic growth, as well as (b) the resilience of their growth with respect to the 2009 global economic shock. Specifically, we explore the role of network efficiency and redundancy using the information theory-based network flow analysis. We find that, while network efficiency is positively correlated with growth, highly efficient systems appear to be less resilient, losing more and gaining less growth following an economic shock. While all examined networks are rather redundant, we find that network redundancy does not hinder their growth. Moreover, systems exhibiting higher levels of redundancy lose less and gain more growth following an economic shock. We suggest that a strategy to support making global trade networks more efficient via, e.g., preferential trade agreements and higher specialization, can promote their further growth; while a strategy to increase the global trade networks' redundancy via e.g., more abundant free-trade agreements, can improve their resilience to global economic shocks.

  2. Growth mechanisms, polytypism, and real structure of kaolinite microcrystals

    SciTech Connect

    Samotoin, N. D.

    2008-09-15

    The mechanisms of growth of kaolinite microcrystals (0.1-5.0 {mu}m in size) at deposits related to the cluvial weathering crust, as well as to the low-temperature and medium-temperature hydrothermal processes of transformations of minerals in different rocks in Russia, Kazakhstan, Ukraine, Czechia, Vietnam, India, Cuba, and Madagascar, are investigated using transmission electron microscopy and vacuum decoration with gold. It is established that kaolinite microcrystals grow according to two mechanisms: the mechanism of periodic formation of two-dimensional nuclei and the mechanism of spiral growth. The spiral growth of kaolinite microcrystals is dominant and occurs on steps of screw dislocations that differ in sign and magnitude of the Burgers vector along the c axis. The layered growth of kaolinite originates from a widespread source in the form of a step between polar (+ and -) dislocations, i.e., a growth analogue of the Frank-Read dislocation source. The density of growth screw dislocations varies over a wide range and can be as high as {approx}10{sup 9} cm{sup -2}. Layered stepped kaolinite growth pyramids for all mechanisms of growth on the (001) face of kaolinite exhibit the main features of the triclinic 1Tc and real structures of this mineral.

  3. Age, growth, mortality, and abundance of lake sturgeon in the Grasse River, New York, USA

    USGS Publications Warehouse

    Trested, D.G.; Isely, J.J.

    2011-01-01

    An increased understanding of lake sturgeon (Acipenser fulvescens) population dynamics is a key requirement for successful management efforts. Little is known regarding the Grasse River population of lake sturgeon except that it is one of a few populations in New York State where spawning has been documented. Thus our purpose was to assess the current status of lake sturgeon in the Grasse River system, including age, growth, mortality, and abundance. Age was determined for 196 of 211 lake sturgeon by examination of sectioned pectoral fin rays. Ages ranged from 0 to 32 years and the annual mortality rate for fish between ages 7 and 14 was 16.8%. The weight (W, g) to total length (TL, mm) relationship was W = 1.281 x 10-6TL3.202. The von Bertalanffy growth equation was TL = 1913(1-e-0.0294(t+9.5691)). While the range of observed ages was similar to that of nearby St. Lawrence River populations, mean weight at age for an individual at 1000 mm TL was lower than that observed for lake sturgeon within Lake St. Francis of the St. Lawrence River. Predicted growth based on von Bertalanffy parameters was similar to that observed for the nearby Lake St. Francis. An open population estimator using the POPAN sub-module in the Program MARK produced an abundance estimate of 793 lake sturgeon (95% CI = 337-1249).

  4. Age, growth, sexual maturity, and food of channel catfish in central Lake Oahe, 1968-69

    USGS Publications Warehouse

    Starostka, Victor J.; Nelson, William R.

    1974-01-01

    Channel catfish, Ictalurus punctatus, were collected with gill nets, trawl, and trap nets at three localities in Lake Oahe for the study of year-class strength, growth in length and weight, age composition, sexual maturity, and food. Fish were recruited to all the collection gears at age II. Relatively strong year classes were produced in 1962, 1965, and 1966. Youngest fish were captured in the upper end of the Moreau River embayment, which apparently serves as a nursery area. Growth of age 0 fish was poor probably because the growing season was short; optimum spawning temperature were not reached until mid-summer. Growth of age II and older fish reached a peak in 1963 and declined rather steadily in 1964-68. Males began to mature at age VIII, and all fish of both sexes were mature at age XI. The diet changed from zooplankton to fish as channel catfish increased in length; aquatic insects (primarily chironomid larvae and pupae) were important foods for fish of all sizes. Fish less than 300 mm long selected large zooplankters -- Leptodora kindtii and Daphnia spp -- over smaller copepods. Larger channel catfish ate principally yellow perch, Perca flavescens.

  5. Insulin-Like Growth Factor Binding Proteins: A Structural Perspective

    PubMed Central

    Forbes, Briony E.; McCarthy, Peter; Norton, Raymond S.

    2012-01-01

    Insulin-like growth factor binding proteins (IGFBP-1 to -6) bind insulin-like growth factors-I and -II (IGF-I and IGF-II) with high affinity. These binding proteins maintain IGFs in the circulation and direct them to target tissues, where they promote cell growth, proliferation, differentiation, and survival via the type 1 IGF receptor. IGFBPs also interact with many other molecules, which not only influence their modulation of IGF action but also mediate IGF-independent activities that regulate processes such as cell migration and apoptosis by modulating gene transcription. IGFBPs-1 to -6 are structurally similar proteins consisting of three distinct domains, N-terminal, linker, and C-terminal. There have been major advances in our understanding of IGFBP structure in the last decade and a half. While there is still no structure of an intact IGFBP, several structures of individual N- and C-domains have been solved. The structure of a complex of N-BP-4:IGF-I:C-BP-4 has also been solved, providing a detailed picture of the structural features of the IGF binding site and the mechanism of binding. Structural studies have also identified features important for interaction with extracellular matrix components and integrins. This review summarizes structural studies reported so far and highlights features important for binding not only IGF but also other partners. We also highlight future directions in which structural studies will add to our knowledge of the role played by the IGFBP family in normal growth and development, as well as in disease. PMID:22654863

  6. Differential effect of aging on axon sprouting and regenerative growth in spinal cord injury.

    PubMed

    Jaerve, Anne; Schiwy, Nora; Schmitz, Christine; Mueller, Hans W

    2011-10-01

    The demographics of acute spinal cord injury (SCI) are changing with an increased incidence in older age. However, the influence of aging on the regenerative growth potential of central nervous system (CNS) axons following SCI is not known. We investigated axonal sprouting along with the efficiency of the infusion of the stromal cell-derived growth factor-1 (SDF-1/CXCL12) and regenerative growth along with the anti-scarring treatment (AST) in young (2-3 months) and geriatric (22-28 months) female rats following SCI. AST included local injection of iron chelator (2,2'-dipyridine-5,5'-dicarboxylic acid) and 8-bromo-cyclic adenosine monophosphate solution into the lesion core. Axon outgrowth was investigated by immunohistological methods at 5 weeks after a partial dorsal hemisection at thoracic level T8. We found that aging significantly reduces spontaneous axon sprouting of corticospinal (CST), serotonergic (5-HT) raphespinal and catecholaminergic (TH) coerulospinal tracts in distinct regions of the spinal cord rostral to the lesion. However, impairment of axon sprouting could be markedly attenuated in geriatric animals by local infusion of SDF-1. Unexpectedly and in contrast to rostral sprouting, aging does not diminish the regenerative growth capacity of 5-HT-, TH- and calcitonin gene-related peptide (CGRP)-immunoreactive axons at 5 weeks after SCI. Moreover, 5-HT and TH axons maintain the ability to react upon AST with significantly enhanced regeneration in aged animals. These data are the first to demonstrate, that old age compromises axonal plasticity, but not regenerative growth, after SCI in a fiber tract-specific manner. Furthermore, AST and SDF-1 infusions remain efficient, which implicates that therapy in elderly patients is still feasible.

  7. Active sensors for health monitoring of aging aerospace structures

    SciTech Connect

    GIURGIUTIU,VICTOR; REDMOND,JAMES M.; ROACH,DENNIS P.; RACKOW,KIRK A.

    2000-03-08

    A project to develop non-intrusive active sensors that can be applied on existing aging aerospace structures for monitoring the onset and progress of structural damage (fatigue cracks and corrosion) is presented. The state of the art in active sensors structural health monitoring and damage detection is reviewed. Methods based on (a) elastic wave propagation and (b) electro-mechanical (NM) impedance technique are sighted and briefly discussed. The instrumentation of these specimens with piezoelectric active sensors is illustrated. The main detection strategies (E/M impedance for local area detection and wave propagation for wide area interrogation) are discussed. The signal processing and damage interpretation algorithms are tuned to the specific structural interrogation method used. In the high-frequency EIM impedance approach, pattern recognition methods are used to compare impedance signatures taken at various time intervals and to identify damage presence and progression from the change in these signatures. In the wave propagation approach, the acoustic-ultrasonic methods identifying additional reflection generated from the damage site and changes in transmission velocity and phase are used. Both approaches benefit from the use of artificial intelligence neural networks algorithms that can extract damage features based on a learning process. Design and fabrication of a set of structural specimens representative of aging aerospace structures is presented. Three built-up specimens, (pristine, with cracks, and with corrosion damage) are used. The specimen instrumentation with active sensors fabricated at the University of South Carolina is illustrated. Preliminary results obtained with the E/M impedance method on pristine and cracked specimens are presented.

  8. Active sensors for health monitoring of aging aerospace structures

    SciTech Connect

    GIURGIUTIU,VICTOR; REDMOND,JAMES M.; ROACH,DENNIS P.; RACKOW,KIRK A.

    2000-02-29

    A project to develop non-intrusive active sensors that can be applied on existing aging aerospace structures for monitoring the onset and progress of structural damage (fatigue cracks and corrosion) is presented. The state of the art in active sensors structural health monitoring and damage detection is reviewed. Methods based on (a) elastic wave propagation and (b) electro-mechanical (E/M) impedance technique are cited and briefly discussed. The instrumentation of these specimens with piezoelectric active sensors is illustrated. The main detection strategies (E/M impedance for local area detection and wave propagation for wide area interrogation) are discussed. The signal processing and damage interpretation algorithms are tuned to the specific structural interrogation method used. In the high-frequency E/M impedance approach, pattern recognition methods are used to compare impedance signatures taken at various time intervals and to identify damage presence and progression from the change in these signatures. In the wave propagation approach, the acousto-ultrasonic methods identifying additional reflection generated from the damage site and changes in transmission velocity and phase are used. Both approaches benefit from the use of artificial intelligence neural networks algorithms that can extract damage features based on a learning process. Design and fabrication of a set of structural specimens representative of aging aerospace structures is presented. Three built-up specimens (pristine, with cracks, and with corrosion damage) are used. The specimen instrumentation with active sensors fabricated at the University of South Carolina is illustrated. Preliminary results obtained with the E/M impedance method on pristine and cracked specimens are presented.

  9. The Effects of Treadmill Running on Aging Laryngeal Muscle Structure

    PubMed Central

    Kletzien, Heidi; Russell, John A.; Connor, Nadine P.

    2015-01-01

    Levels of Evidence NA (animal study) Objective Age-related changes in laryngeal muscle structure and function may contribute to deficits in voice and swallowing observed in elderly people. We hypothesized that treadmill running, an exercise that increases respiratory drive to upper airway muscles, would induce changes in thyroarytenoid muscle myosin heavy chain (MHC) isoforms consistent with a fast-slow transformation in muscle fiber type. Study Design Randomized parallel group controlled trial. Methods Fifteen young adult and 14 old Fischer 344/Brown Norway rats received either treadmill running or no exercise (5 days/week/8 weeks). Myosin heavy chain isoform composition in the thyroarytenoid muscle was examined at the end of 8 weeks. Results Significant age and treatment effects were found. The young adult group had the greatest proportion of superfast contracting MHCIIL. The treadmill running group had the lowest proportion of MHCIIL and the greatest proportion of MHCIIx. Conclusion Thyroarytenoid muscle structure was affected both by age and treadmill running in a fast-slow transition that is characteristic of exercise manipulations in other skeletal muscles. PMID:26256100

  10. Growth, structure, morphology, and magnetic properties of Ni ferrite films

    PubMed Central

    2013-01-01

    The morphology, structure, and magnetic properties of nickel ferrite (NiFe2O4) films fabricated by radio frequency magnetron sputtering on Si(111) substrate have been investigated as functions of film thickness. Prepared films that have not undergone post-annealing show the better spinel crystal structure with increasing growth time. Meanwhile, the size of grain also increases, which induces the change of magnetic properties: saturation magnetization increased and coercivity increased at first and then decreased. Note that the sample of 10-nm thickness is the superparamagnetic property. Transmission electron microscopy displays that the film grew with a disorder structure at initial growth, then forms spinel crystal structure as its thickness increases, which is relative to lattice matching between substrate Si and NiFe2O4. PMID:23622034

  11. Making the Right Moves: Promoting Smart Growth and Active Aging in Communities

    EPA Science Inventory

    This article describes an award program sponsored by the U.S. Environmental Protection Agency for excellence in smart growth and active aging. Having examined qualitative and quantitative data, we suggest that any community can foster changes to improve the health and well-being ...

  12. Differential Effects of Intelligence, Perceptual Speed and Age on Growth in Attentional Speed and Accuracy

    ERIC Educational Resources Information Center

    Goldhammer, Frank; Rauch, Wolfgang A.; Schweizer, Karl; Moosbrugger, Helfried

    2010-01-01

    The study investigates the effects of intelligence, perceptual speed and age on intraindividual growth in attentional speed and attentional accuracy over the course of a 6-minute testing session. A sample of 193 subjects completed the Advanced Progressive Matrices and the Vienna Matrices Test representing intelligence, the tests Alertness and…

  13. Age at first reproduction and growth rate are independent of basal metabolic rate in mammals.

    PubMed

    Lovegrove, Barry G

    2009-05-01

    This study tested an emergent prediction from the Metabolic Theory of Ecology (MTE) that the age at first reproduction (alpha) of a mammal is proportional to the inverse of its mass-corrected basal metabolic rate: alpha proportional (B / M)-1 The hypothesis was tested with multiple regression models of conventional species data and phylogenetically independent contrasts of 121 mammal species. Since age at first reproduction is directly influenced by an individual's growth rate, the hypothesis that growth rate is proportional to BMR was also tested. Although the overall multiple regression model was significant, age at first reproduction was not partially correlated with either body mass, growth rate or BMR. Similarly, growth rate was not correlated with BMR. Thus at least for mammals in general, there is no evidence to support the fundamental premise of the MTE that individual metabolism governs the rate at which energy is converted to growth and reproduction at the species level. The exponents of the BMR allometry calculated using phylogenetic generalized least squares regression models were significantly lower than the three-quarter value predicted by the MTE.

  14. Definitions of fitness in age-structured populations: Comparison in the haploid case.

    PubMed

    Lessard, Sabin; Soares, Cintia

    2016-02-21

    Fisher's (1930) Fundamental Theorem of Natural Selection (FTNS), and in particular the development of an explicit age-structured version of the theorem, is of everlasting interest. In a recent paper, Grafen (2015a) argues that Fisher regarded his theorem as justifying individual rather than population fitness maximization. The argument relies on a new definition of fitness in age-structured populations in terms of individual birth and death rates and age-specific reproductive values in agreement with a principle of neutrality. The latter are frequency-dependent and defined without reference to genetic variation. In the same paper, it is shown that the rate of increase in the mean of the breeding values of fitness weighted by the reproductive values, but keeping the breeding values constant as in Price (1972) is equal to the additive genetic variance in fitness. Therefore, this partial change is obtained by keeping constant not only the genotypic birth and death rates but also the mean age-specific birth and death rates from which the age-specific reproductive values are defined. In this paper we reaffirm that the Malthusian parameter which measures the relative rate of increase or decrease in reproductive value of each genotype in a continuous-time age-structured population is the definition of fitness used in Fisher's (1930) FTNS. This is shown by considering an age-structured asexual haploid population with constant age-specific birth and death (or survival) parameters for each type. Although the original statement of the FTNS is for a diploid population, this simplified haploid model allows us to address the definition of fitness meant in this theorem without the complexities and effects of a changing genic environment. In this simplified framework, the rate of change in mean fitness in continuous time is expected to be exactly equal to the genetic variance in fitness (or to the genetic variance in fitness divided by the mean fitness in discrete time), which can

  15. Associations between iron oxyhydroxide nanoparticle growth and metal adsorption/structural incorporation

    SciTech Connect

    Kim, C.S.; Lentini, C.J.; Waychunas, G.A.

    2008-09-15

    The interaction of metal ions and oxyanions with nanoscale mineral phases has not yet been extensively studied despite the increased recognition of their prevalence in natural systems as a significant component of geomedia. A combination of macroscopic uptake studies to investigate the adsorption behavior of As(V), Cu(II), Hg(II), and Zn(II) onto nanoparticulate goethite ({alpha}-FeOOH) as a function of aging time at elevated temperature (75 C) and synchrotron-based X-ray studies to track changes in both the sorption mode and the rate of nanoparticle growth reveal the effects that uptake has on particle growth. Metal(loid) species which sorb quickly to the iron oxyhydroxide particles (As(V), Cu(II)) appear to passivate the particle surface, impeding the growth of the nanoparticles with progressive aging; in contrast, species that sorb more slowly (Hg(II), Zn(II)) have considerably less impact on particle growth. Progressive changes in the speciation of these particular metals with time suggest shifts in the mode of metal uptake with time, possibly indicating structural incorporation of the metal(loid) into the nanoparticle; this is supported by the continued increase in uptake concomitant with particle growth, implying that metal species may transform from surface-sorbed species to more structurally incorporated forms. This type of incorporation would have implications for the long-term fate and mobility of metals in contaminated regions, and affect the strategy for potential remediation/modeling efforts.

  16. Predicting tree biomass growth in the temperate-boreal ecotone: Is tree size, age, competition, or climate response most important?

    PubMed

    Foster, Jane R; Finley, Andrew O; D'Amato, Anthony W; Bradford, John B; Banerjee, Sudipto

    2016-06-01

    As global temperatures rise, variation in annual climate is also changing, with unknown consequences for forest biomes. Growing forests have the ability to capture atmospheric CO2 and thereby slow rising CO2 concentrations. Forests' ongoing ability to sequester C depends on how tree communities respond to changes in climate variation. Much of what we know about tree and forest response to climate variation comes from tree-ring records. Yet typical tree-ring datasets and models do not capture the diversity of climate responses that exist within and among trees and species. We address this issue using a model that estimates individual tree response to climate variables while accounting for variation in individuals' size, age, competitive status, and spatially structured latent covariates. Our model allows for inference about variance within and among species. We quantify how variables influence aboveground biomass growth of individual trees from a representative sample of 15 northern or southern tree species growing in a transition zone between boreal and temperate biomes. Individual trees varied in their growth response to fluctuating mean annual temperature and summer moisture stress. The variation among individuals within a species was wider than mean differences among species. The effects of mean temperature and summer moisture stress interacted, such that warm years produced positive responses to summer moisture availability and cool years produced negative responses. As climate models project significant increases in annual temperatures, growth of species like Acer saccharum, Quercus rubra, and Picea glauca will vary more in response to summer moisture stress than in the past. The magnitude of biomass growth variation in response to annual climate was 92-95% smaller than responses to tree size and age. This means that measuring or predicting the physical structure of current and future forests could tell us more about future C dynamics than growth responses

  17. Predicting tree biomass growth in the temperate-boreal ecotone: is tree size, age, competition or climate response most important?

    USGS Publications Warehouse

    Foster, Jane R.; Finley, Andrew O.; D'Amato, Anthony W.; Bradford, John B.; Banerjee, Sudipto

    2016-01-01

    As global temperatures rise, variation in annual climate is also changing, with unknown consequences for forest biomes. Growing forests have the ability to capture atmospheric CO2and thereby slow rising CO2 concentrations. Forests’ ongoing ability to sequester C depends on how tree communities respond to changes in climate variation. Much of what we know about tree and forest response to climate variation comes from tree-ring records. Yet typical tree-ring datasets and models do not capture the diversity of climate responses that exist within and among trees and species. We address this issue using a model that estimates individual tree response to climate variables while accounting for variation in individuals’ size, age, competitive status, and spatially structured latent covariates. Our model allows for inference about variance within and among species. We quantify how variables influence aboveground biomass growth of individual trees from a representative sample of 15 northern or southern tree species growing in a transition zone between boreal and temperate biomes. Individual trees varied in their growth response to fluctuating mean annual temperature and summer moisture stress. The variation among individuals within a species was wider than mean differences among species. The effects of mean temperature and summer moisture stress interacted, such that warm years produced positive responses to summer moisture availability and cool years produced negative responses. As climate models project significant increases in annual temperatures, growth of species likeAcer saccharum, Quercus rubra, and Picea glauca will vary more in response to summer moisture stress than in the past. The magnitude of biomass growth variation in response to annual climate was 92–95% smaller than responses to tree size and age. This means that measuring or predicting the physical structure of current and future forests could tell us more about future C dynamics than growth

  18. Radiocarbon-Based Ages and Growth Rates of Bamboo Corals from the Gulf of Alaska

    SciTech Connect

    Roark, E B; Guilderson, T P; Flood-Page, S; Dunbar, R B; Ingram, B L; Fallon, S J; McCulloch, M

    2004-12-12

    Deep-sea coral communities have long been recognized by fisherman as areas that support large populations of commercial fish. As a consequence, many deep-sea coral communities are threatened by bottom trawling. Successful management and conservation of this widespread deep-sea habitat requires knowledge of the age and growth rates of deep-sea corals. These organisms also contain important archives of intermediate and deep-water variability, and are thus of interest in the context of decadal to century-scale climate dynamics. Here, we present {Delta}{sup 14}C data that suggest that bamboo corals from the Gulf of Alaska are long-lived (75-126 years) and that they acquire skeletal carbon from two distinct sources. Independent verification of our growth rate estimates and coral ages is obtained by counting seasonal Sr/Ca cycles and probable lunar cycle growth bands.

  19. Latent Growth Curves within Developmental Structural Equation Models.

    ERIC Educational Resources Information Center

    McArdle, J. J.; Epstein, David

    1987-01-01

    Uses structural equation modeling to combine traditional ideas from repeated-measures ANOVA with some traditional ideas from longitudinal factor analysis. The model describes a latent growth curve model that permits the estimation of parameters representing individual and group dynamics. (Author/RH)

  20. Measuring the growth rate of structure around cosmic voids

    NASA Astrophysics Data System (ADS)

    Hawken, A. J.; Michelett, D.; Granett, B.; Iovino, A.; Guzzo, L.

    2016-10-01

    Using an algorithm based on searching for empty spheres we identified 245 voids in the VIMOS Public Extragalactic Redshift Survey (VIPERS). We show how by modelling the anisotropic void-galaxy cross correlation function we can probe the growth rate of structure.

  1. Growth hormone-releasing peptide-6 inhibits cerebellar cell death in aged rats.

    PubMed

    Pañeda, Covadonga; Arroba, Ana I; Frago, Laura M; Holm, Anne Mette; Rømer, John; Argente, Jesús; Chowen, Julie A

    2003-08-26

    Insulin-like growth factor (IGF)-I is essential for cerebellar granule neuron survival and a decline in IGF-I is implicated in various age-dependent processes. Here we show that IGF-I mRNA levels are decreased in the cerebellum of old rats compared with young rats and this was associated with increased cell death and activation of caspases 3 and 9. Growth hormone-releasing peptide (GHRP)-6, a synthetic ligand for the ghrelin receptor, increased IGF-I mRNA levels, decreased cell death and inhibited caspase 3 and 9 activation in the cerebellum of aged rats. These results suggest that increasing IGF-I expression in the cerebellum can decrease cell death in aged rats via inhibition of caspase 3 and 9 activation.

  2. Age and growth of the knobbed whelk Busycon carica (Gmelin 1791) in South Carolina subtidal waters

    USGS Publications Warehouse

    Eversole, A.G.; Anderson, W.D.; Isely, J.J.

    2008-01-01

    Knobbed whelk, Busycon carica (Gmelin, 1791), age and growth were estimated using tagged and recaptured individuals (n = 396) from areas off South Carolina coastal islands. Recaptured whelks were at large an average of 298 d (4-2,640 d). Growth, an increase in shell length (SL), was evident in 24% of the recaptured whelks, whereas 29% of recaptured individuals were the same size as when released and 47% were smaller than the released size. Mean growth rate was <0.001 mm SL/d and 0.022 mm SL/d if decreases in SL were assumed to be zero. Smaller whelks (???90 mm SL) at large for over one year grew seven times faster than larger whelks. The von Bertalanffy growth model: SL1 = 159.5(1 - e-0.0765(t+0.4162)), was developed from the mark - recapture whelks exhibiting growth. Based on a South Carolina minimum legal size of 102 mm SL, whelks recruit into the fishery at 13 y of age. The longevity, large size at maturity and slow growth suggest the potential for over harvest of knobbed whelk. Future whelk management plans may wish to consider whether economically viable commercial harvest can be sustainable.

  3. Effect of Growth Hormone Deficiency on Brain Structure, Motor Function and Cognition

    ERIC Educational Resources Information Center

    Webb, Emma A.; O'Reilly, Michelle A.; Clayden, Jonathan D.; Seunarine, Kiran K.; Chong, Wui K.; Dale, Naomi; Salt, Alison; Clark, Chris A.; Dattani, Mehul T.

    2012-01-01

    The growth hormone-insulin-like growth factor-1 axis plays a role in normal brain growth but little is known of the effect of growth hormone deficiency on brain structure. Children with isolated growth hormone deficiency (peak growth hormone less than 6.7 [micro]g/l) and idiopathic short stature (peak growth hormone greater than 10 [micro]g/l)…

  4. A Study of Correlation of Various Growth Indicators with Chronological Age

    PubMed Central

    Sandhu, Navreet; Puri, Taruna; Gulati, Ritika; Kashyap, Rita

    2015-01-01

    ABSTRACT Introduction: The aim of this study was to assess the relationship of chronological age with cervical vertebrae skeletal maturation, frontal sinus width and antegonial notch depth and a correlation, if any, among the three variables. Materials and methods: The samples were derived from lateral cephalometric radiographs of 80 subjects (40 males, 40 females; age range: 10 to 19 years). Cervical vertebral development was evaluated by the method of Hassel and Farman, frontal sinus width was measured by the method described by Ertürk and antegonial notch depth as described by Singer et al. The Pearson’s correlation coefficients were estimated to assess the relationship of chronological age with cervical vertebrae skeletal maturation, frontal sinus width and antegonial notch depth. Results: The Pearson’s correlation coefficient were 0.855 (p < 0.001) between chronological age and cervical vertebrae skeletal maturation, and 0.333 (p < 0.001) between chronological age and frontal sinus width. Conclusion: A highly significant positive correlation was found between chronological age and cervical vertebrae skeletal maturation, and between chronological age and frontal sinus width. Nonsignificant correlation was found between chronological age and antegonial notch depth. How to cite this article: Singh S, Sandhu N, Puri T, Gulati R, Kashyap R. A Study of Correlation of Various Growth Indicators with Chronological Age. Int J Clin Pediatr Dent 2015;8(3): 190-195. PMID:26628853

  5. Protective actions of melatonin and growth hormone on the aged cardiovascular system.

    PubMed

    Paredes, Sergio D; Forman, Katherine A; García, Cruz; Vara, Elena; Escames, Germaine; Tresguerres, Jesús A F

    2014-05-01

    Epidemiological studies indicate that certain aspects of lifestyle and genetics act as risk factors for a variety of cardiovascular disorders, including coronary disease, hypertension, heart failure and stroke. Aging, however, appears to be the major contributor for morbidity and mortality of the impaired cardiovascular system. Growth hormone (GH) and melatonin seem to prevent cardiac aging, as they contribute to the recovery of several physiological parameters affected by age. These hormones exhibit antioxidant properties and decrease oxidative stress and apoptosis. This paper summarizes a set of studies related to the potential role that therapy with GH and melatonin may play in the protection of the altered cardiac function due to aging, with a focus on experiments performed in our laboratory using the senescence-accelerated mouse as an aging model. In general, we observed significantly increased inflammation, oxidative stress and apoptosis markers in hearts from senescence-accelerated prone 10-month-old animals compared to 2-month-old controls, while anti-inflammatory and antiapoptotic markers as well as endothelial nitric oxide synthase were decreased. Senescence-accelerated resistant animals showed no significant changes with age. GH or melatonin treatment prevented the age-dependent cardiac alterations observed in the senescence-accelerated prone group. Combined administration of GH plus melatonin reduced the age-related changes in senescence-accelerated prone hearts in an additive fashion that was different to that displayed when administered alone. GH and melatonin may be potential agents for counteracting oxidative stress, apoptosis and inflammation in the aging heart.

  6. The Oportunidades program increases the linear growth of children enrolled at young ages in urban Mexico.

    PubMed

    Leroy, Jef L; García-Guerra, Armando; García, Raquel; Dominguez, Clara; Rivera, Juan; Neufeld, Lynnette M

    2008-04-01

    The goal of this study was to evaluate the impact of Mexico's conditional cash transfer program, Oportunidades, on the growth of children <24 mo of age living in urban areas. Beneficiary families received cash transfers, a fortified food (targeted to pregnant and lactating women, children 6-23 mo, and children with low weight 2-4 y), and curative health services, among other benefits. Program benefits were conditional on preventative health care utilization and attendance of health and nutrition education sessions. We estimated the impact of the program after 2 y of operation in a panel of 432 children <24 mo of age at baseline (2002). We used difference-in-difference propensity score matching, which takes into account nonrandom program participation and the effects of unobserved fixed characteristics on outcomes. All models controlled for child age, sex, baseline anthropometry, and maternal height. Anthropometric Z-scores were calculated using the new WHO growth reference standards. There was no overall association between program participation and growth in children 6 to 24 mo of age. Children in intervention families younger than 6 mo of age at baseline grew 1.5 cm (P < 0.05) more than children in comparison families, corresponding to 0.41 height-for-age Z-scores (HAZ) (P < 0.05). They also gained an additional 0.76 kg (P < 0.01) or 0.47 weight-for-height Z-scores (P < 0.05). Children living in the poorest intervention households tended (0.05 < P < 0.10) to be taller than comparison children (0.9 cm, 0.27 HAZ). Oportunidades, with its strong nutrition component, is an effective tool to improve the growth of infants in poor urban households.

  7. Growth rate and age distribution of deep-sea black corals in the Gulf of Mexico

    USGS Publications Warehouse

    Prouty, N.G.; Roark, E.B.; Buster, N.A.; Ross, S.W.

    2011-01-01

    Black corals (order Antipatharia) are important long-lived, habitat-forming, sessile, benthic suspension feeders that are found in all oceans and are usually found in water depths greater than 30 m. Deep-water black corals are some of the slowest-growing, longest-lived deep-sea corals known. Previous age dating of a limited number of black coral samples in the Gulf of Mexico focused on extrapolated ages and growth rates based on skeletal 210Pb dating. Our results greatly expand the age and growth rate data of black corals from the Gulf of Mexico. Radiocarbon analysis of the oldest Leiopathes sp. specimen from the upper De Soto Slope at 300 m water depth indicates that these animals have been growing continuously for at least the last 2 millennia, with growth rates ranging from 8 to 22 µm yr–1. Visual growth ring counts based on scanning electron microscopy images were in good agreement with the 14C-derived ages, suggestive of annual ring formation. The presence of bomb-derived 14C in the outermost samples confirms sinking particulate organic matter as the dominant carbon source and suggests a link between the deep-sea and surface ocean. There was a high degree of reproducibility found between multiple discs cut from the base of each specimen, as well as within duplicate subsamples. Robust 14C-derived chronologies and known surface ocean 14C reservoir age constraints in the Gulf of Mexico provided reliable calendar ages with future application to the development of proxy records.

  8. 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

  9. Alliance for aging research AD biomarkers work group: structural MRI.

    PubMed

    Jack, Clifford R

    2011-12-01

    Biomarkers of Alzheimer's disease (AD) are increasingly important. All modern AD therapeutic trials employ AD biomarkers in some capacity. In addition, AD biomarkers are an essential component of recently updated diagnostic criteria for AD from the National Institute on Aging--Alzheimer's Association. Biomarkers serve as proxies for specific pathophysiological features of disease. The 5 most well established AD biomarkers include both brain imaging and cerebrospinal fluid (CSF) measures--cerebrospinal fluid Abeta and tau, amyloid positron emission tomography (PET), fluorodeoxyglucose (FDG) positron emission tomography, and structural magnetic resonance imaging (MRI). This article reviews evidence supporting the position that MRI is a biomarker of neurodegenerative atrophy. Topics covered include methods of extracting quantitative and semiquantitative information from structural MRI; imaging-autopsy correlation; and evidence supporting diagnostic and prognostic value of MRI measures. Finally, the place of MRI in a hypothetical model of temporal ordering of AD biomarkers is reviewed.

  10. Development and growth of long bones in European water frogs (Amphibia: Anura: Ranidae), with remarks on age determination.

    PubMed

    Rozenblut, Beata; Ogielska, Maria

    2005-09-01

    Differentiation and development of long bones were studied in European water frogs: Rana lessonae, R. ridibunda, and R. esculenta. The study included premetamorphic larvae (Gosner Stage 40) to frogs that were 5 years old. Femora, metatarsal bones, and proximal phalanges of the hindlimb exhibit the same pattern of periosteal bone differentiation and the same pattern of growth. Longitudinal and radial growth of these bones was studied by examination of the diaphyses and epiphyses, particularly where the edge of periosteal bone is inserted into the epiphysis. The periosteum seems to be responsible for both longitudinal and radial growth. Investigation of the formation, length, and arrangement of lines of arrested growth reveals that the first line is present only in the middle 25-35% of the length of the diaphysis of an adult bone; therefore, only the central portion of the diaphysis should be used for age estimation in skeletochronological studies. Comparison of the shapes and histological structures of epiphyses in the femur, metatarsal bones, and phalanges revealed that epiphyseal cartilages are composed of an inner and outer part. The inner metaphyseal cartilage has distinct zones and plugs the end of the periosteal bone cylinder; its role in longitudinal growth is questioned. The outer epiphyseal cartilage is composed of articular cartilages proper, in addition to lateral articular cartilages. Differences in the symmetry of the lateral articular cartilages of distal epiphyses of the femur and toes may reflect adaptations to different kinds of movements at the knee and in the foot.

  11. Age-related changes in bone structure and strength in female and male BALB/c mice.

    PubMed

    Willinghamm, Mark D; Brodt, Michael D; Lee, Kristen L; Stephens, Abby L; Ye, Jiaxin; Silva, Matthew J

    2010-06-01

    Mice may be useful for studies of skeletal aging, but there are limited data on changes in bone structure and strength over their life span. We obtained bones from female and male BALB/c mice at ages 2, 4, 7, 12, and 20 months and evaluated their structural, densitometric, and mechanical properties. MicroCT of the mid-diaphysis of the femur and radius indicated that during skeletal growth (2-7 months) bone cross-sectional size (area, moment of inertia) increased rapidly; during aging (7-20 months) cortical area was maintained, while moment of inertia continued to increase. Bones from females were smaller than those from males at young ages but not at later ages. Changes in whole-bone stiffness and strength reflected the changes in bone size, with a rapid increase from 2 to 7 months, followed by little or no change. In contrast, energy-to-fracture declined with aging. Cortical tissue mineral density increased during growth and was maintained with aging. MicroCT of trabecular bone revealed age-related changes that were site-dependent. The proximal tibia showed a clear pattern of age-related decline in trabecular BV/TV, with progressive decreases after 4 months in both sexes; lumbar vertebra L5 had more modest age-related declines; in contrast, caudal vertebra Ca7 had increasing BV/TV with aging. Overall, we found no evidence that females had more pronounced age-related deterioration than males. We conclude that bones from aging female and male BALB/c mice exhibit many of the changes seen in humans and are therefore a clinically relevant model for studies of skeletal aging.

  12. Structural development of redwood branches and its effects on wood growth.

    PubMed

    Kramer, Russell D; Sillett, Stephen C; Carroll, Allyson L

    2014-03-01

    Redwood branches provide all the carbohydrates for the most carbon-heavy forests on Earth, and recent whole-tree measurements have quantified trunk growth rates associated with complete branch inventories. Providing all of a tree's photosynthetic capacity, branches represent an increasing proportion of total aboveground wood production as trees enlarge. To examine branch development and its effects on wood volume growth, we dissected 31 branches from eight Sequoia sempervirens (D. Don) Endl. and seven Sequoiadendron giganteum Lindl. trees. The cambium-area-to-leaf-area ratio was maintained with size and age but increased with light availability, whereas the heartwood-deposition-area-to-leaf-area ratio increased with size and age but was insensitive to light availability. The proportion of foliage mass arrayed in <1-cm-diameter epicormic shoots increased with decreasing light and was higher in Sequoia (20-60%) than in Sequoiadendron (3-16%). Well-illuminated branches concentrated leaves higher and distally, while shaded branches distributed leaves lower and proximally. In similar light environments, older branches distributed leaves lower and more proximally than younger branches. Branch size, light, species, heartwood area, a heartwood-area-species interaction, and ovulate cone mass predicted 87.5% of the variability in wood volume growth of branches. After accounting for the positive effects of size and light, wood volume growth declined with heartwood area and age. The effect of age was trivial compared to the effect of heartwood area, suggesting that heartwood expansion caused the age-related decline in wood volume growth. Additionally, Sequoiadendron branches of similar size and light environment with more ovulate cones produced less wood, even though these cones were long-lived and photosynthetic, reflecting the energetic cost of seed production. These results contributed to a conceptual model of branch development in which light availability, injury

  13. Modeling age-specific cancer incidences using logistic growth equations: implications for data collection.

    PubMed

    Shen, Xing-Rong; Feng, Rui; Chai, Jing; Cheng, Jing; Wang, De-Bin

    2014-01-01

    Large scale secular registry or surveillance systems have been accumulating vast data that allow mathematical modeling of cancer incidence and mortality rates. Most contemporary models in this regard use time series and APC (age-period-cohort) methods and focus primarily on predicting or analyzing cancer epidemiology with little attention being paid to implications for designing cancer registry, surveillance or evaluation initiatives. This research models age-specific cancer incidence rates using logistic growth equations and explores their performance under different scenarios of data completeness in the hope of deriving clues for reshaping relevant data collection. The study used China Cancer Registry Report 2012 as the data source. It employed 3-parameter logistic growth equations and modeled the age-specific incidence rates of all and the top 10 cancers presented in the registry report. The study performed 3 types of modeling, namely full age-span by fitting, multiple 5-year- segment fitting and single-segment fitting. Measurement of model performance adopted adjusted goodness of fit that combines sum of squred residuals and relative errors. Both model simulation and performance evalation utilized self-developed algorithms programed using C# languade and MS Visual Studio 2008. For models built upon full age-span data, predicted age-specific cancer incidence rates fitted very well with observed values for most (except cervical and breast) cancers with estimated goodness of fit (Rs) being over 0.96. When a given cancer is concerned, the R valuae of the logistic growth model derived using observed data from urban residents was greater than or at least equal to that of the same model built on data from rural people. For models based on multiple-5-year-segment data, the Rs remained fairly high (over 0.89) until 3-fourths of the data segments were excluded. For models using a fixed length single-segment of observed data, the older the age covered by the corresponding

  14. [The demographic aging of the Austrian population: on the long-term changes in the age structure in Austria].

    PubMed

    Kytir, J

    1995-01-01

    "The Austrian population is presently in the middle of its age structure transition which started with World War I and will continue until the 40s of the next century. Within this time period the number of people aged 60 years or over will increase from about half a million to 2.8 million (1995: 1.6 million) and the share of the elderly will mount from about 9 percent to more than 35 percent (1995: 20 percent). The present article points out the demographic causes for population aging asking whether high fertility and/or high numbers of migrants can stop the aging process. Different measurements of demographic aging in Austria (share of various age groups, mean age and median age, dependency ratios, several aging indices) are calculated for the time period 1869 to 2050. Special attention is paid to regional differences within Austria and to changes of the sex ratio at older ages over time." (EXCERPT)

  15. Impact of structural aging on seismic risk assessment of reinforced concrete structures in nuclear power plants

    SciTech Connect

    Ellingwood, B.; Song, J.

    1996-03-01

    The Structural Aging Program is addressing the potential for degradation of concrete structural components and systems in nuclear power plants over time due to aging and aggressive environmental stressors. Structures are passive under normal operating conditions but play a key role in mitigating design-basis events, particularly those arising from external challenges such as earthquakes, extreme winds, fires and floods. Structures are plant-specific and unique, often are difficult to inspect, and are virtually impossible to replace. The importance of structural failures in accident mitigation is amplified because such failures may lead to common-cause failures of other components. Structural condition assessment and service life prediction must focus on a few critical components and systems within the plant. Components and systems that are dominant contributors to risk and that require particular attention can be identified through the mathematical formalism of a probabilistic risk assessment, or PRA. To illustrate, the role of structural degradation due to aging on plant risk is examined through the framework of a Level 1 seismic PRA of a nuclear power plant. Plausible mechanisms of structural degradation are found to increase the core damage probability by approximately a factor of two.

  16. Age and growth of round gobies in Lake Huron: Implications for food web dynamics

    USGS Publications Warehouse

    Duan, You J.; Madenjian, Charles P.; Xie, Cong X.; Diana, James S.; O'Brien, Timothy P.; Zhao, Ying M.; He, Ji X.; Farha, Steve A.; Huo, Bin

    2016-01-01

    Although the round goby (Neogobius melanostomus) has become established throughout the Laurentian Great Lakes, information is scarce on spatial variation in round goby growth between and within lakes. Based on a sample of 754 specimens captured in 2014, age, growth, and mortality of round gobies at four locations in Lake Huron were assessed via otolith analysis. Total length (TL) of round gobies ranged from 44 to 111 mm for Saginaw Bay, from 45 to 115 mm for Rockport, from 50 to 123 mm for Hammond Bay, and from 51 to 118 mm for Thunder Bay. Estimated ages of round gobies ranged from 2 to 5 years for Saginaw Bay, from 2 to 6 years for Rockport, and from 2 to 7 years for Hammond Bay and Thunder Bay. Sex-specific, body–otolith relationships were used to back-calculate total lengths at age, which were then fitted to von Bertalanffy growth models. For each sex, round goby growth showed significant spatial variation among the four locations within Lake Huron. At all four locations in Lake Huron, males grew significantly faster than females and attained a larger asymptotic length than females. Annual mortality rate estimates were high (62 to 85%), based on catch-curve analysis, suggesting that round gobies may be under predatory control in Lake Huron.

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

    USGS Publications Warehouse

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

    2015-01-01

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

  18. Age, growth, and reproductive biology of three catostomids from the Apalachicola River, Florida

    USGS Publications Warehouse

    Grabowski, Timothy B.; Young, S.P.; Isely, J.J.; Ely, Patrick C.

    2012-01-01

    Riverine catostomids can show a wide range of interspecific variation in life-history characteristics. Understanding these differences is an important consideration in evaluating the sensitivity of these fishes to disturbance and in formulating effective conservation strategies, particularly when dealing with an assemblage consisting of multiple species within a watershed. We collected Apalachicola redhorse Moxostoma n. sp. cf. poecilurum (n = 125), spotted sucker Minytrema melanops (n = 94), and quillback Carpiodes cyprinus (n = 94) to determine age, growth, and reproductive biology of spawning catostomids in the Apalachicola River, Florida, during 2007. Quillback was the smallest in total length at age; longest-lived; most fecund; and produced the smallest eggs. Apalachicola redhorse was the largest in body size; had an intermediate life span; and produced the fewest yet largest eggs. Spotted sucker was more similar to Apalachicola redhorse in most characteristics. Growth during ages 1-3 in all three species seemed to be negatively related to the proportion of observations of extreme flow, both high (Q90) and low (Q10), per year and a positive response in growth rate to high flows (>Q75 but < Q90). However, Apalachicola redhorse and spotted sucker growth was more sensitive to flow conditions than that of quillback. Our results suggest the life histories and ecological response of Apalachicola River catostomids to flow regulation are important components for developing strategies that incorporate the needs of these fishery resources into an ecosystem-based management approach.

  19. Bayesian analysis of the dynamic structure in China's economic growth

    NASA Astrophysics Data System (ADS)

    Kyo, Koki; Noda, Hideo

    2008-11-01

    To analyze the dynamic structure in China's economic growth during the period 1952-1998, we introduce a model of the aggregate production function for the Chinese economy that considers total factor productivity (TFP) and output elasticities as time-varying parameters. Specifically, this paper is concerned with the relationship between the rate of economic growth in China and the trend in TFP. Here, we consider the time-varying parameters as random variables and introduce smoothness priors to construct a set of Bayesian linear models for parameter estimation. The results of the estimation are in agreement with the movements in China's social economy, thus illustrating the validity of the proposed methods.

  20. Effects of ration and temperature on growth of age-0 Atlantic sturgeon

    USGS Publications Warehouse

    Kelly, J.L.; Arnold, D.E.

    1999-01-01

    Our objective was to gain insight into the optimum temperature and ration for growth of age-0 Atlantic sturgeon Acipenser oxyrinchus in culture. We conducted two trials, each for 8 weeks. Trial 1 started with 60-g fish, trial 2 started with 0 3-g fish. Water temperatures of 15, 17, and 19??C were used separately in each trial. Rations (dry food, wet weight of fish) for 60-g fish were 0.5, 1.0, and 1.5% of biomass per day, for 0.3-g fish, rations were 3, 5, and 7% of biomass per day. We set up three tank replicates, of equal fish biomass, at each combination of temperature and ration. The highest growth rate in trial 1 (for 60-g fish) was 0.014/d at 15??C and the 1.5% ration, although this growth rate was not significantly different from the growth rate at 17??C and 1.5% ration or at 17??C and 1.0% ration. The highest growth rate in trial 2 (for 0.3-g fish) was 0.067/d at 19??C and the 7.0% ration. Instantaneous growth at these conditions was significantly different from all other combinations of temperature and ration. Although these results may not completely define the temperature and ration under which fish could achieve maximum growth rate, they provide a solid starting point for further development of Atlantic sturgeon culture.

  1. Conservation of acquired morphology and community structure in aged biofilms after facing environmental stress.

    PubMed

    Saur, T; Escudié, R; Santa-Catalina, G; Bernet, N; Milferstedt, K

    2016-01-01

    The influence of growth history on biofilm morphology and microbial community structure is poorly studied despite its important role for biofilm development. Here, biofilms were exposed to a change in hydrodynamic conditions at different growth stages and we observed how biofilm age affected the change in morphology and bacterial community structure. Biofilms were developed in two bubble column reactors, one operated under constant shear stress and one under variable shear stress. Biofilms were transferred from one reactor to the other at different stages in their development by withdrawing and inserting the support medium from one reactor to the other. The developments of morphology and microbial community structure were followed by image analysis and molecular tools. When transferred early in biofilm development, biofilms adapted to the new hydrodynamic conditions and adopted features of the biofilm already developed in the receiving reactor. Biofilms transferred at a late state of biofilm development continued their initial trajectories of morphology and community development even in a new environment. These biofilms did not immediately adapt to their new environment and kept features acquired during their early growth phase, a property we called memory effect.

  2. Advances in Structural Integrity Analysis Methods for Aging Metallic Airframe Structures with Local Damage

    NASA Technical Reports Server (NTRS)

    Starnes, James H., Jr.; Newman, James C., Jr.; Harris, Charles E.; Piascik, Robert S.; Young, Richard D.; Rose, Cheryl A.

    2003-01-01

    Analysis methodologies for predicting fatigue-crack growth from rivet holes in panels subjected to cyclic loads and for predicting the residual strength of aluminum fuselage structures with cracks and subjected to combined internal pressure and mechanical loads are described. The fatigue-crack growth analysis methodology is based on small-crack theory and a plasticity induced crack-closure model, and the effect of a corrosive environment on crack-growth rate is included. The residual strength analysis methodology is based on the critical crack-tip-opening-angle fracture criterion that characterizes the fracture behavior of a material of interest, and a geometric and material nonlinear finite element shell analysis code that performs the structural analysis of the fuselage structure of interest. The methodologies have been verified experimentally for structures ranging from laboratory coupons to full-scale structural components. Analytical and experimental results based on these methodologies are described and compared for laboratory coupons and flat panels, small-scale pressurized shells, and full-scale curved stiffened panels. The residual strength analysis methodology is sufficiently general to include the effects of multiple-site damage on structural behavior.

  3. mTOR: from growth signal integration to cancer, diabetes and ageing

    PubMed Central

    Zoncu, Roberto; Sabatini, David M.; Efeyan, Alejo

    2012-01-01

    Preface In all eukaryotes, the target of rapamycin (TOR) signaling pathway couples energy and nutrient abundance to the execution of cell growth and division, owing to the ability of TOR protein kinase to simultaneously sense energy, nutrients and stress, and, in metazoan, growth factors. Mammalian TOR complexes 1 and 2 (mTORC1 and mTORC2) exert their actions by regulating other important kinases, such as S6K and Akt. In the last few years, a significant advance in our understanding of the regulation and functions of mTOR has revealed its critical involvement in the onset and progression of diabetes, cancer and ageing. PMID:21157483

  4. Age, growth and maturity of the pelagic thresher Alopias pelagicus and the scalloped hammerhead Sphyrna lewini.

    PubMed

    Drew, M; White, W T; Dharmadi; Harry, A V; Huveneers, C

    2015-01-01

    Indonesia has the greatest reported chondrichthyan catches worldwide, with c.110,000 t caught annually. The pelagic thresher (Alopias pelagicus) and scalloped hammerhead (Sphryna lewini) together comprise about 25% of the total catches of sharks landed in Indonesia. Age and growth parameters were estimated for A. pelagicus and S. lewini from growth-band counts of thin-cut vertebral sections. Alopias pelagicus (n = 158) and S. lewini (n = 157) vertebrae were collected from three Indonesian fish markets over a 5 year period. A multi-model analysis was used to estimate growth parameters for both species. The models of best fit for males and females for A. pelagicus was the three-parameter logistic (L∞ = 3169 mm LT , k = 0·2) and the two-parameter von Bertalanffy models (L∞ = 3281 mm LT , k = 0·12). Age at maturity was calculated to be 10·4 and 13·2 years for males and females, respectively, and these are the oldest estimated for this species. The samples of S. lewini were heavily biased towards females, and the model of best fit for males and females was the three-parameter Gompertz (L∞ = 2598 mm LT , k = 0·15) and the two-parameter Gompertz (L∞ = 2896 mm LT , k= 0·16). Age at maturity was calculated to be 8·9 and 13·2 years for males and females, respectively. Although numerous age and growth studies have previously been undertaken on S. lewini, few studies have been able to obtain adequate samples from all components of the population because adult females, adult males and juveniles often reside in different areas. For the first time, sex bias in this study was towards sexually mature females, which are commonly lacking in previous biological studies on S. lewini. Additionally, some of the oldest aged specimens and highest age at maturity for both species were observed in this study. Both species exhibit slow rates of growth and late age at maturity, highlighting the need for a re-assessment of the relative resilience of these two

  5. Age, differential growth and mortality rates in unexploited populations of Florida gar, an apex predator in the Florida Everglades

    USGS Publications Warehouse

    Murie, D.J.; Parkyn, D.C.; Nico, L.G.; Herod, J.J.; Loftus, W.F.

    2009-01-01

    Florida gar, Lepisosteus platyrhincus DeKay, were sampled in two canal systems in south Florida during 2000-2001 to estimate age, growth and mortality as part of the Everglades ecosystem-restoration effort. Tamiami (C-4) and L-31W canal systems had direct connections to natural wetlands of the Everglades and harboured large Florida gar populations. Of 476 fish aged, maximum ages were 19 and 10years for females and males, respectively. Maximum sizes were also larger for females compared with males (817 vs 602 mm total length). Overall, female Florida gar from both Tamiami and L-31W were larger at age than males from L-31W that, in turn, were larger at any given age than males from Tamiami. Females also had lower rates of annual mortality (Z = 0.21) than males from L-31W (Z = 0.31) or males from Tamiami (Z = 0.54). As a large and long-lived apex predator in the Everglades, Florida gar may structure lower trophic levels. Regional- and sex-specific population parameters for Florida gar will contribute to the simulation models designed to evaluate Everglades restoration alternatives. ?? 2009 Blackwell Publishing Ltd.

  6. Optimum temperature for growth and preferred temperatures of age-0 lake trout

    USGS Publications Warehouse

    Edsall, Thomas A.; Cleland, Joshua

    2000-01-01

    This study was performed to determine the thermal preferences and optimum temperature for growth of age-0 lake trout Salvelinus namaycush to help predict the thermal habitat they select when they leave the spawning grounds and to assess the risk posed to them in the Great Lakes by piscivorus, nonnative fishes whose thermal habitat preferences are known. The test fish were hatched in the laboratory from eggs taken from wild fish, acclimated to 5, 10, 15, and 18°C, and fed to excess with commercial trout food for 47 d. The test fish grew at all of the temperatures, and the specific growth rate was highest at about 12.5°C (3.8% wet body weight/d). Fish used in the growth study were also tested in a vertical thermal gradient tank and had a final thermal preferendum between 10.1°C and 10.2°C. These results, which generally agreed with those of an earlier laboratory study of the temperature preference of age-1 lake trout and the limited information on thermal habitat use by age-0 lake trout in the Great Lakes, indicated age-0 lake trout would tend to seek temperatures near 10°C, or as high as 12.5°C, during summer if food was abundant. Published information on thermal habitat use of age-1 and adult alewives Alosa pseudoharengus and rainbow smelt Osmerus mordax indicated they would be expected to co-occur with age-0 lake trout during much of the time when the lake trout were small enough to be eaten by these two introduced piscivores.

  7. A size-structured model of bacterial growth and reproduction.

    PubMed

    Ellermeyer, S F; Pilyugin, S S

    2012-01-01

    We consider a size-structured bacterial population model in which the rate of cell growth is both size- and time-dependent and the average per capita reproduction rate is specified as a model parameter. It is shown that the model admits classical solutions. The population-level and distribution-level behaviours of these solutions are then determined in terms of the model parameters. The distribution-level behaviour is found to be different from that found in similar models of bacterial population dynamics. Rather than convergence to a stable size distribution, we find that size distributions repeat in cycles. This phenomenon is observed in similar models only under special assumptions on the functional form of the size-dependent growth rate factor. Our main results are illustrated with examples, and we also provide an introductory study of the bacterial growth in a chemostat within the framework of our model.

  8. Effect of intensified feeding of heifer calves on growth, pubertal age, calving age, milk yield, and economics.

    PubMed

    Davis Rincker, L E; Vandehaar, M J; Wolf, C A; Liesman, J S; Chapin, L T; Weber Nielsen, M S

    2011-07-01

    The objective of this study was to determine if increasing the energy and protein intake of heifer calves would affect growth rates, age at puberty, age at calving, and first lactation milk yield. A second objective was to perform an economic analysis of this feeding program using feed costs, number of nonproductive days, and milk yield data. Holstein heifer calves born at the Michigan State Dairy Cattle Teaching and Research Center were randomly assigned to 1 of 2 dietary treatments (n=40/treatment) that continued from 2 d of age until weaning at 42 d of age. The conventional diet consisted of a standard milk replacer [21.5% crude protein (CP), 21.5% fat] fed at 1.2% of body weight (BW) on a dry matter basis and starter grain (19.9% CP) to attain 0.45 kg of daily gain. The intensive diet consisted of a high-protein milk replacer (30.6% CP, 16.1% fat) fed at 2.1% of BW on a dry matter basis and starter grain (24.3% CP) to achieve 0.68 kg of daily gain. Calves were gradually weaned from milk replacer by decreasing the amount offered for 5 and 12 d before weaning for the conventional and intensive diets, respectively. All calves were completely weaned at 42 d of age and kept in hutches to monitor individual starter consumption in the early postweaning period. Starting from 8 wk of age, heifers on both treatments were fed and managed similarly for the duration of the study. Body weight and skeletal measurements were taken weekly until 8 wk of age, and once every 4 wk thereafter until calving. Calves consuming the intensive diet were heavier, taller, and wider at weaning. The difference in withers height and hip width was carried over into the early post-weaning period, but a BW difference was no longer evident by 12 wk of age. Calves fed the intensive diet were younger and lighter at the onset of puberty. Heifers fed the high-energy and protein diet were 15 d younger at conception and 14 d younger at calving than heifers fed the conventional diet. Body weight after

  9. Aging Optimization of Aluminum-Lithium Alloy C458 for Application to Cryotank Structures

    NASA Technical Reports Server (NTRS)

    Sova, B. J.; Sankaran, K. K.; Babel, H.; Farahmand, B.; Rioja, R.

    2003-01-01

    Compared with aluminum alloys such as 2219, which is widely used in space vehicle for cryogenic tanks and unpressurized structures, aluminum-lithium alloys possess attractive combinations of lower density and higher modulus along with comparable mechanical properties. These characteristics have resulted in the successful use of the aluminum-lithium alloy 2195 (Al-1.0 Li-4.0 Cu-0.4 Mg-0.4 Ag-0.12 Zr) for the Space Shuttle External Tank, and the consideration of newer U.S. aluminum-lithium alloys such as L277 and C458 for future space vehicles. These newer alloys generally have lithium content less than 2 wt. % and their composition and processing have been carefully tailored to increase the toughness and reduce the mechanical property anisotropy of the earlier generation alloys such 2090 and 8090. Alloy processing, particularly the aging treatment, has a significant influence on the strength-toughness combinations and their dependence on service environments for aluminum-lithium alloys. Work at NASA Marshall Space Flight Center on alloy 2195 has shown that the cryogenic toughness can be improved by employing a two-step aging process. This is accomplished by aging at a lower temperature in the first step to suppress nucleation of the strengthening precipitate at sub-grain boundaries while promoting nucleation in the interior of the grains. Second step aging at the normal aging temperature results in precipitate growth to the optimum size. A design of experiments aging study was conducted for plate. To achieve the T8 temper, Alloy C458 (Al-1.8 Li-2.7 Cu-0.3 Mg- 0.08 Zr-0.3 Mn-0.6 Zn) is typically aged at 300 F for 24 hours. In this study, a two-step aging treatment was developed through a comprehensive 24 full factorial design of experiments study and the typical one-step aging used as a reference. Based on the higher lithium content of C458 compared with 2195, the first step aging temperature was varied between 175 F and 250 F. The second step aging temperatures was

  10. Structure and growth mechanism of ZnSe nanowires

    SciTech Connect

    Basu, Joysurya; Carter, C. Barry; Divakar, R.; Nowak, Julia; Hofmann, Stephan; Colli, Alan; Franciosi, A

    2008-09-15

    ZnSe nanowires were grown onto Mo transmission electron microscopy (TEM) grids by MBE by suitably varying the growth parameters. In situ and high-resolution TEM studies were carried out to understand the structure, defects, and growth mechanism of this nanowire. The nanowire morphology is very sensitive to the growth parameters involved. Twin boundaries are the most commonly occurring defects in the nanowires grown under Zn-rich condition and catalytic gold particles of irregular shape are observed along the nanowire body. In the course of in situ heating the shape of the nanowire tip is observed to change at {approx}178 deg. C. Definite growth of the nanowire starts at {approx}235 deg. C. The diameter of the grown nanowire is almost equal to that of the catalyst gold particle present at the tip of the nanowire. In situ experimental observation and available phase-diagram information strongly suggests that nanowire growth should be possible with a solid catalyst particle though it does not rule out the possibility of the existence of a VLS mechanism.

  11. Structure of S-shaped growth in innovation diffusion.

    PubMed

    Shimogawa, Shinsuke; Shinno, Miyuki; Saito, Hiroshi

    2012-05-01

    A basic question on innovation diffusion is why the growth curve of the adopter population in a large society is often S shaped. From macroscopic, microscopic, and mesoscopic viewpoints, the growth of the adopter population is observed as the growth curve, individual adoptions, and differences among individual adoptions, respectively. The S shape can be explained if an empirical model of the growth curve can be deduced from models of microscopic and mesoscopic structures. However, even the structure of growth curve has not been revealed yet because long-term extrapolations by proposed models of S-shaped curves are unstable and it has been very difficult to predict the long-term growth and final adopter population. This paper studies the S-shaped growth from the viewpoint of social regularities. Simple methods to analyze power laws enable us to extract the structure of the growth curve directly from the growth data of recent basic telecommunication services. This empirical model of growth curve is singular at the inflection point and a logarithmic function of time after this point, which explains the unstable extrapolations obtained using previously proposed models and the difficulty in predicting the final adopter population. Because the empirical S curve can be expressed in terms of two power laws of the regularity found in social performances of individuals, we propose the hypothesis that the S shape represents the heterogeneity of the adopter population, and the heterogeneity parameter is distributed under the regularity in social performances of individuals. This hypothesis is so powerful as to yield models of microscopic and mesoscopic structures. In the microscopic model, each potential adopter adopts the innovation when the information accumulated by the learning about the innovation exceeds a threshold. The accumulation rate of information is heterogeneous among the adopter population, whereas the threshold is a constant, which is the opposite of previously

  12. Tectonic structures on Mercury: kinematics and age dating

    NASA Astrophysics Data System (ADS)

    Giacomini, Lorenza; Massironi, Matteo; Rothery, David; Di Achille, Gaetano; Marchi, Simone; Galluzzi, Valentina; Ferrari, Sabrina; Fassett, Caleb; Cremonese, Gabriele

    2015-04-01

    At a global scale, Mercury is dominated by contractional features manifested as lobate scarps, wrinkle ridges and high-relief ridges. Here, we show that some of these features are associated with strike-slip kinematic indicators, which we identified using flyby and orbital Mercury Dual Imaging System (MDIS) data and digital terrain models. We recognize oblique-shear kinematics along lobate scarps and high-relief ridges by means of (1) map geometries of fault patterns (frontal thrusts bordered by lateral ramps, strike-slip duplexes, restraining bends); (2) structural morphologies indicating lateral shearing (en echelon folding, pop-ups, pull-aparts); and (3) estimates of offsets based on displaced crater rims and differences in elevation between pop-up structures and pull-apart basins and their surroundings. Transpressional faults, documented across a wide range of latitudes, are found associated with reactivated rims of ancient buried basins and, in most cases, linked to frontal thrusts as lateral ramps hundreds of kilometres long. This latter observation suggests stable directions of tectonic transport over wide regions of Mercury's surface. In contrast, global cooling would imply an overall isotropic contraction with limited processes of lateral shearing induced by pre-existent lithospheric heterogeneities. Mantle convection therefore may have played an important role during the early tectonic evolution of Mercury. Estimating absolute model ages for compressional features and comparing it from what it is envisaged with thermal modeling based on cooling alone can be useful in determining if other processes could have been responsible for lobate scarps nucleation. In particular, ages more ancient that the one predicted by the models would imply other kind of tectonic processes ongoing during the early evolution of Mercury . For this reason, we date an extended thrust system, which we term the Blossom Thrust System, located between 80°E and 100°E, and 30°N and 15

  13. [Economic growth and changes in the structure of the population].

    PubMed

    Conroy, M E

    1980-01-01

    A reevaluation of classic works by Simon Kuznets and Wassily Leontief suggests that their conclusions concerning the interrelationships between economic growth and population structure correspond to relatively highly specialized characteristics of present forms of capitalist development or underdevelopment and not necessarily to capitalist development within a new international economic order or to socialist development. Kuznets' work seems to offer conclusive proof of the negative effects of rapid population growth on economic development for 3 reasons: 1) requirements for capital are greater, 2) total production and per capita consumption are greatly reduced with high dependency ratios, and 3) rapid growth in consumption is more difficult when the population is growing more rapidly. However, at least 4 problems are noted when Kuznets' ideas are applied to the 3rd world. Kuznets assumes that growth of physical capital is the only source of growth, so that only increased investment can increase returns. Secondly, assuming the same ratio of capital/output for all cases assumes that no substitution of labor for capital is possible. Third, the assumption that participation rates remain the same regardless of dependency ratios may be incorrect. And finally, the difference in per capita consumption that Kuznets attributes to differences in rates of population growth represents a tiny proportion of the total gap in the standard of living of rich countries with slow population growth and poor countries with rapid growth. Kuznets' argument has considerable validity in Third World countries which relay on traditional patterns of capitalist accumulation, but the problems represent the effects of rapid population growth only under the current modes of capitalist expansion. The negative effect of high fertility on savings has probably been greatly exaggerated, and the problems of providing educational facilities and health care for ever larger numbers of persons have been

  14. Molecular design for growth of supramolecular membranes with hierarchical structure.

    PubMed

    Zha, R Helen; Velichko, Yuri S; Bitton, Ronit; Stupp, Samuel I

    2016-02-07

    Membranes with hierarchical structure exist in biological systems, and bio-inspired building blocks have been used to grow synthetic analogues in the laboratory through self-assembly. The formation of these synthetic membranes is initiated at the interface of two aqueous solutions, one containing cationic peptide amphiphiles (PA) and the other containing the anionic biopolymer hyaluronic acid (HA). The membrane growth process starts within milliseconds of interface formation and continues over much longer timescales to generate robust membranes with supramolecular PA-HA nanofibers oriented orthogonal to the interface. Computer simulation indicates that formation of these hierarchically structured membranes requires strong interactions between molecular components at early time points in order to generate a diffusion barrier between both solutions. Experimental studies using structurally designed PAs confirm simulation results by showing that only PAs with high ζ potential are able to yield hierarchically structured membranes. Furthermore, the chemical structure of such PAs must incorporate residues that form β-sheets, which facilitates self-assembly of long nanofibers. In contrast, PAs that form low aspect ratio nanostructures interact weakly with HA and yield membranes that exhibit non-fibrous fingering protrusions. Furthermore, experimental results show that increasing HA molecular weight decreases the growth rate of orthogonal nanofibers. This result is supported by simulation results suggesting that the thickness of the interfacial contact layer generated immediately after initiation of self-assembly increases with polymer molecular weight.

  15. Individual heterogeneity in growth and age at sexual maturity: A gamma process analysis of capture–mark–recapture data

    USGS Publications Warehouse

    Link, William; Hesed, Kyle Miller

    2015-01-01

    Knowledge of organisms’ growth rates and ages at sexual maturity is important for conservation efforts and a wide variety of studies in ecology and evolutionary biology. However, these life history parameters may be difficult to obtain from natural populations: individuals encountered may be of unknown age, information on age at sexual maturity may be uncertain and interval-censored, and growth data may include both individual heterogeneity and measurement errors. We analyzed mark–recapture data for Red-backed Salamanders (Plethodon cinereus) to compare sex-specific growth rates and ages at sexual maturity. Aging of individuals was made possible by the use of a von Bertalanffy model of growth, complemented with models for interval-censored and imperfect observations at sexual maturation. Individual heterogeneity in growth was modeled through the use of Gamma processes. Our analysis indicates that female P. cinereus mature earlier and grow more quickly than males, growing to nearly identical asymptotic size distributions as males.

  16. Growth of children with Down's syndrome: birth to age 3 years.

    PubMed

    Cronk, C E

    1978-04-01

    A sample of 90 children with Down's syndrome were measured for recumbent length and weight from birth to age 36 months at the Children's Hospital Medical Center in Boston. At birth, means for both length and weight were reduced by about 0.5 SDs from the control group means. By 36 months, mean recumbent length was greater than 2 SDs below that for the control group, while the mean for weight was reduced by about 1.5 SDs from the control group mean. Growth velocity for both length and weight was most deficient within the first two years of life. About 30% of the sample demonstrated excess weight for length relations by 36 months. Children with moderate or severe heart disease were significantly smaller than those without or with mild cardiac problems at all times after birth. Measurements of a subsample of children at 4, 5, and 6 years of age suggested that growth velocity after 3 years of age may be within the range of normal. Assessment of growth of the child with Down's syndrome may be carried out with reference to charts plotting tenth to 90th percentiles based on these data.

  17. Age and growth of the rock bass, Ambloplites rupestris (Rafinesque), in Nebish Lake, Wisconsin

    USGS Publications Warehouse

    Hile, Ralph

    1941-01-01

    studies of the age and growth of the rock bass (Wright, 1929), whitefish (Hile and Deason, 1934), yellow perch (Schneberger, 1935), cisco (Hile, 1936a), muskellunge (Schloemer, 1936, 1938), largemouth black bass (Bennett, 1937), common sucker (Spoor, 1938), and smalimouth black bass (Bennett, 1938). A total of five mimeographed reports on the growth of game fish in Wisconsin has been issued by Juday and Schneberger (1930, 1933), Juday and Bennett (1935), and Juday and Schloemer (1936,. 1938). In addition there have appeared two publications on the morphometry of the cisco (Hile 193Gb, 1937), three dealing with the parasites of fishes in the region (Cross 1934, 1935, 1938) and one on the food of fishes (Couey, 1935). A paper by Hile and Juday on the bathymetric distribution of fish will appear simultaneously with the present study of the rock bass. A contribution on the growth of the bluegill by Schloemer will be published in the near future.

  18. Age, growth and reproduction of Sarcocheilichthys nigripinnis from the Qingyi Stream in the Huangshan Mountains.

    PubMed

    Yan, Yunzhi; Xu, Yinsheng; Chu, Ling; He, Shan; Chen, Yifeng

    2012-06-01

    Identifying the life-history strategies of fish and their associations with the surrounding environment is the basic foundation in the conservation and sustainable utilization of fish species. We examined the age, growth, and reproduction of Sarcocheilichthys nigripinnis using 352 specimens collected monthly from May 2009 to April 2010 in the Qingyi Stream. We found the sex ratio of this study population was 0.58:1 (female: male), significantly different from expected 1:1. Females and males both comprised four age groups. The annuli on the scales were formed during February and March. No obvious between-sex difference was observed in length-weight and length-scale-radius relationships. The total length in back-calculation significantly increased with age for both sexes, but did not differ significantly at each age between the two sexes. An inflection point was observed in the growth curves given by the von Bertalanffy growth function for total weight. At this inflection point, fish were 3.95 years. Both sexes reach their 50% sex maturity at age 2, when females and males were 94.7 mm and 103.0 mm total length. The temporal pattern of the gonado-somatic index corresponded to a spawning period that occurred from April through July. The non-synchronicity of egg diameter in each mature ovary during the breeding period suggested these fish may be batch spawners. The absolute fecundity increased significantly with total length and weight, whereas no significant correlation was observed between the relative fecundity and body size.

  19. Femoral head epiphysis growth and development among Chinese children aged 0-5 years.

    PubMed

    Luo, Jiayou; Tang, Jin; Zhou, Libo; Zeng, Rong; Mou, Jinsong; Zhang, Lingli

    2009-05-01

    The aim of this study was to examine the pattern of femoral head epiphysis growth and development among Chinese children. Between January and December, 2007, we randomly sampled 1,450 healthy Chinese children (0-5 years old) from Hunan Provincial Children's Hospital in Changsha, Hunan, China. The diameter of femoral head epiphysis was measured by pelvic X-ray photography and processed by medical image processing software. The growth of femoral head epiphysis in girls was 2-3 months earlier than that in boys. The diameter of femoral head epiphysis increased with advancing age in both girls and boys, but the diameter of femoral head epiphysis in 2, 3, 4, 6, and 10-month-old girls was significantly larger than that in boys. Cubic regression equations between the diameter of femoral head epiphysis and age were created for boys and girls that could be used to predict the diameter of femoral head epiphysis. In conclusion, there was gender difference in femoral head epiphysis growth and development among Chinese children, and our prediction models will provide the guidance for early diagnosis of diseases related to the growth and development of the femoral head epiphysis.

  20. Growth of Geographic Atrophy in the Comparison of Age-related Macular Degeneration Treatments Trials (CATT)

    PubMed Central

    Grunwald, Juan E; Pistilli, Maxwell; Ying, Gui-shuang; Maguire, Maureen G; Daniel, Ebenezer; Martin, Daniel F

    2014-01-01

    Purpose To evaluate the growth of geographic atrophy (GA) during anti-VEGF therapy. Design Cohort within clinical trial. Participants Patients included in the Comparison of Age-related Macular Degeneration (AMD) Treatments Trials (CATT) Methods Participants were randomly assigned to injections of ranibizumab or bevacizumab and to a 2-year dosing regimen of monthly or pro re nata (PRN), or to monthly for 1 year and PRN the following year. Digital color photographs and fluorescein angiograms at baseline, 1 and 2 years were evaluated for GA and the total area of GA was measured by two graders masked to treatment; differences were adjudicated. Multivariate linear mixed models of the annual change in the square root of the area included baseline demographic, treatment, and ocular characteristics on imaging as candidate risk factors. Main outcome measures GA growth rate. Results Among 1185 participants, 86 (7.3%) had GA at baseline, 120 (10.1%) developed GA during year 1 and 36 (3.0%) during year 2. Among 194 eyes evaluable for growth, the rate was 0.43 (standard error [SE]: ±0.03) mm/year. In multivariate analysis, the growth rate was 0.37 mm/year in eyes receiving bevacizumab and 0.49 mm/year in eyes receiving ranibizumab (difference 0.11, 95% Confidence Interval [CI]: (0.01, 0.22); p=0.03). Growth rate did not differ between eyes treated monthly and PRN (p=0.85). Eyes with subfoveal CNV lesions had a lower growth rate than eyes with non-subfoveal CNV lesions (difference 0.12, CI: 0.01, 0.22; p=0.03). Eyes with GA farther from the fovea had higher growth rates by 0.14 (CI: 0.01, 27) mm/year for every mm farther from the fovea. The growth rate was 0.58 mm/year for eyes with predominantly classic lesions, 0.41 mm/year for eyes with minimally classic lesions, and 0.30 mm/year for eyes with occult only lesions (p<0.01). The growth rate in eyes having a fellow eye with GA was higher by 0.13 (CI: 0.01, 0.24; p=0.03) mm/year than in eyes without GA in the fellow eye. Eyes

  1. Cohort study of growth patterns by gestational age in preterm infants developing morbidity

    PubMed Central

    Klevebro, S; Lundgren, P; Hammar, U; Smith, L E; Bottai, M; Domellöf, M; Löfqvist, C; Hallberg, B; Hellström, A

    2016-01-01

    Objectives To examine differences in growth patterns in preterm infants developing major morbidities including retinopathy of prematurity (ROP), bronchopulmonary dysplasia (BPD), necrotising enterocolitis (NEC) and intraventricular haemorrhage (IVH). Study design Cohort study of 2521 infants born at a gestational age (GA) of 23–30 weeks from 11 level III neonatal intensive care units in USA and Canada, and 3 Swedish population-based cohorts. Outcomes Birth weight and postnatal weight gain were examined relative to birth GA and ROP, BPD, NEC and IVH development. Results Among infants with a birth GA of 25–30 weeks, birth weight SD score and postnatal weight were lower in those developing ROP and BPD. Infants developing ROP showed lower growth rates during postnatal weeks 7–9 in the 23–24 weeks GA group, during weeks 4–6 in the 25–26 weeks GA group and during weeks 1–5 in the 27–30 weeks GA group. Infants with BPD born at 27–30 weeks GA showed lower growth rates during postnatal weeks 3–5. Infants with NEC had lower growth rates after postnatal week 6 in all GA groups, with no significant differences in birth weight SD score. IVH was not associated with prenatal or postnatal growth. Conclusions In this cohort study of extremely preterm infants, we found that the postnatal growth pattern was associated with morbidities such as ROP, BPD and NEC as well as with gestational age at birth. PMID:27856479

  2. 76 FR 69292 - Aging Management of Stainless Steel Structures and Components in Treated Borated Water

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-08

    ... COMMISSION Aging Management of Stainless Steel Structures and Components in Treated Borated Water AGENCY... Staff Guidance (LR-ISG), LR- ISG-2011-01, ``Aging Management of Stainless Steel Structures and... Learned (GALL) Report for the aging management of stainless steel structures and components exposed...

  3. Physics of Lipofuscin Formation and Growth in Age Related Macular Degeneration

    NASA Astrophysics Data System (ADS)

    Family, Fereydoon; Mazzitello, K. I.; Arizmendi, C. M.; Grossniklaus, Hans E.

    2010-02-01

    Age-related macular degeneration (AMD) is the leading cause of blindness beyond the age of 50 years. The most common pathogenic mechanism that leads to AMD is choroidal neovascularization (CNV). CNV is produced by accumulation of residual material caused by aging of retinal pigment epithelium cells (RPE). With time, incompletely degraded membrane material builds up in the RPE in the form of lipofuscin. Lipofuscin is made of free-radical-damaged protein and fat, which forms not only in AMD, but also Alzheimer disease, and Parkinson disease. We will present the results of a study of the kinetics of lipofuscin growth in RPE cells using Kinetic Monte Carlo simulations and scaling theory on a cluster aggregation model. The model captures the essential physics of lipofuscin growth in the cells. A remarkable feature is that small particles may be removed from the cells while the larger ones become fixed and grow by aggregation. We compare our results to the number of lipofuscin granules in eyes with early age-related degeneration. )

  4. Age, growth and natural mortality of coney (Cephalopholis fulva) from the southeastern United States

    PubMed Central

    Potts, Jennifer C.; Carr, Daniel R.

    2015-01-01

    Coney (Cephalopholis fulva) sampled from recreational and commercial vessels along the southeastern coast of the United States in 1998–2013 (n = 353) were aged by counting opaque bands on sectioned sagittal otoliths. Analysis of otolith edge type (opaque or translucent) revealed that annuli formed in January–June with a peak in April. Coney were aged up to 19 years, and the largest fish measured 430 mm in total length (TL). The weight-length relationship was ln(W) = 3.03 × ln(TL) − 18.05 (n = 487; coefficient of determination [r2] = 0.91), where W = whole weight in kilograms and and TL = total length in millimeters. Mean observed sizes at ages 1, 3, 5, 10, and 19 years were 225, 273, 307, 338, and 400 mm TL, respectively. The von Bertalanffy growth equation for coney was Lt = 377 (1 − e(−0.20(t+3.53))). Natural mortality (M) estimated by Hewitt and Hoenig’s longevity-based method which integrates all ages was 0.22. Age-specific M values, estimated with the method of Charnov and others, were 0.40, 0.30, 0.26, 0.22, and 0.20 for ages 1, 3, 5, 10, and 19, respectively. PMID:25802801

  5. Aging, Maturation and Growth of Sauropodomorph Dinosaurs as Deduced from Growth Curves Using Long Bone Histological Data: An Assessment of Methodological Constraints and Solutions

    PubMed Central

    Griebeler, Eva Maria; Klein, Nicole; Sander, P. Martin

    2013-01-01

    Information on aging, maturation, and growth is important for understanding life histories of organisms. In extinct dinosaurs, such information can be derived from the histological growth record preserved in the mid-shaft cortex of long bones. Here, we construct growth models to estimate ages at death, ages at sexual maturity, ages at which individuals were fully-grown, and maximum growth rates from the growth record preserved in long bones of six sauropod dinosaur individuals (one indeterminate mamenchisaurid, two Apatosaurus sp., two indeterminate diplodocids, and one Camarasaurus sp.) and one basal sauropodomorph dinosaur individual (Plateosaurus engelhardti). Using these estimates, we establish allometries between body mass and each of these traits and compare these to extant taxa. Growth models considered for each dinosaur individual were the von Bertalanffy model, the Gompertz model, and the logistic model (LGM), all of which have inherently fixed inflection points, and the Chapman-Richards model in which the point is not fixed. We use the arithmetic mean of the age at the inflection point and of the age at which 90% of asymptotic mass is reached to assess respectively the age at sexual maturity or the age at onset of reproduction, because unambiguous indicators of maturity in Sauropodomorpha are lacking. According to an AIC-based model selection process, the LGM was the best model for our sauropodomorph sample. Allometries established are consistent with literature data on other Sauropodomorpha. All Sauropodomorpha reached full size within a time span similar to scaled-up modern mammalian megaherbivores and had similar maximum growth rates to scaled-up modern megaherbivores and ratites, but growth rates of Sauropodomorpha were lower than of an average mammal. Sauropodomorph ages at death probably were lower than that of average scaled-up ratites and megaherbivores. Sauropodomorpha were older at maturation than scaled-up ratites and average mammals, but

  6. Statistical growths of turbulent structures in a pipe flow

    NASA Astrophysics Data System (ADS)

    Ahn, Junsun; Sung, Hyung Jin

    2016-11-01

    The streamwise and spanwise (or azimuthal) growths of turbulent coherent structures in a turbulent pipe flow (Reτ = 3008) are explored. Two-point correlation and 1-D pre-multiplied energy spectra of the streamwise velocity fluctuations are obtained to analyze the statistical growths of the streamwise and spanwise structures. The streamwise and spanwise length scales linearly grow along the wall-normal distance and the relationship between both length scales is shown to be linear, which support the attached eddy hypothesis. Furthermore, the statistical scalings of the coherent structures are demonstrated and compared to 2-D pre-multiplied energy spectra of the streamwise velocity fluctuations. Finally, the relationship between the streamwise and spanwise structures is analyzed by using the POD based on the translational invariance method (Duggleby et al. 2009). Several representative energetic modes are observed. The combinations of the energetic modes are used to examine the behaviors of the large- and very-large-scale motions. This work was supported by the Creative Research Initiatives (No. 2016-004749) program of the National Research Foundation of Korea (MSIP) and partially supported by KISTI under the Strategic Supercomputing Support Program.

  7. Jatropha curcas L. Root Structure and Growth in Diverse Soils

    PubMed Central

    Valdés-Rodríguez, Ofelia Andrea; Sánchez-Sánchez, Odilón; Pérez-Vázquez, Arturo; Caplan, Joshua S.; Danjon, Frédéric

    2013-01-01

    Unlike most biofuel species, Jatropha curcas has promise for use in marginal lands, but it may serve an additional role by stabilizing soils. We evaluated the growth and structural responsiveness of young J. curcas plants to diverse soil conditions. Soils included a sand, a sandy-loam, and a clay-loam from eastern Mexico. Growth and structural parameters were analyzed for shoots and roots, although the focus was the plasticity of the primary root system architecture (the taproot and four lateral roots). The sandy soil reduced the growth of both shoot and root systems significantly more than sandy-loam or clay-loam soils; there was particularly high plasticity in root and shoot thickness, as well as shoot length. However, the architecture of the primary root system did not vary with soil type; the departure of the primary root system from an index of perfect symmetry was 14 ± 5% (mean ± standard deviation). Although J. curcas developed more extensively in the sandy-loam and clay-loam soils than in sandy soil, it maintained a consistent root to shoot ratio and root system architecture across all types of soil. This strong genetic determination would make the species useful for soil stabilization purposes, even while being cultivated primarily for seed oil. PMID:23844412

  8. The growth of structure in interacting dark energy models

    SciTech Connect

    Caldera-Cabral, Gabriela; Maartens, Roy; Schaefer, Bjoern Malte E-mail: roy.maartens@port.ac.uk

    2009-07-01

    If dark energy interacts with dark matter, there is a change in the background evolution of the universe, since the dark matter density no longer evolves as a{sup −3}. In addition, the non-gravitational interaction affects the growth of structure. In principle, these changes allow us to detect and constrain an interaction in the dark sector. Here we investigate the growth factor and the weak lensing signal for a new class of interacting dark energy models. In these models, the interaction generalises the simple cases where one dark fluid decays into the other. In order to calculate the effect on structure formation, we perform a careful analysis of the perturbed interaction and its effect on peculiar velocities. Assuming a normalization to today's values of dark matter density and overdensity, the signal of the interaction is an enhancement (suppression) of both the growth factor and the lensing power, when the energy transfer in the background is from dark matter to dark energy (dark energy to dark matter)

  9. 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.

  10. [Age identification and growth characteristics of Katsuwonus pelamis in western and central Pacific Ocean].

    PubMed

    Wang, Xue-Fang; Xu, Liu-Xiong; Zhu, Guo-Ping; Wang, Chun-Lei

    2010-03-01

    Fish age and growth are the important biological parameters for the assessment of fishery resources. With the help of purse seiners, 262 individuals of skipjack tuna (Katsuwonus pelamis) were sampled from western and central Pacific Ocean in October 2007 - January 2008. The measurements in situ showed that the fork length of the samples ranged from 278 to 746 mm, and their body mass ranged from 345 to 9905 g. The first dorsal spine of each individual was collected for age identification and growth parameters estimation. The relationship between fork length (L, mm) and body mass (M, g) was expressed as M = 3.612 x 10(-6) L3.278 (R2 = 0.9782), and no significant difference was found for the males and females (F = 2.002, P > 0.05). A comparison with Akaike information criterion (AIC) suggested that among power regression equation, linear regression equation, and exponential regression equation, linear regression equation was most suitable for describing the relationship between fork length and spine radius (AIC = 2257.4). The mean back-calculated fork lengths of K. pelamis with the ages of 1-5 estimated by Fraser-Lee's method were 398.4, 494.2, 555.4, 636.8, and 728.8 mm, respectively. Residual analyses indicated that there was no significant difference in the growth of male and female K. pelamis (F = 0.670; df = 182; P > 0.05). The sex-combined von Bertalanffy growth equation of K. pelamis was L(t) = 706.51 (1 - e(-0.64(t + 0.037))).

  11. Fatigue and fatigue crack growth processes in hard tissues: The importance of age and surface integrity

    NASA Astrophysics Data System (ADS)

    Majd, Hessam

    With the progressive increase in partially and fully dentate seniors, fracture has become an increasingly common form of restored tooth failure. Dentin undergoes progressive changes in microstructure with patient age, and studies are now suggesting that there is a reduction in fatigue strength and fatigue crack growth resistance of this tissue. This dissertation explores aging of dentin, the influence of flaws that are introduced during restorative processes on the fatigue properties of dentin, and proposes models for characterizing the damage initiation and growth process during fatigue of dentin. Results from this investigation show that the fatigue crack growth properties (Paris Law parameters (C, m) andDeltaKth) of human dentin undergo the most significant changes at a patient age of 42 years. Based on the fatigue crack growth responses, three age groups were established including young (age≤33), aged (34≤age ≤49) and old (50≤age) patients for further analysis. There were significant differences in the initiation and growth behavior between the tissues of patients from the three age groups. With regards to the influence of restorative processes, there was no influence on the quasi-static responses of dentin. However, the endurance limit of dentin treated with the dental burs (28 MPa) and abrasive air jet (35 MPa) were approximately 36% and 20% lower than that of the control (44 MPa), respectively. Both cutting processes caused a significant reduction (p≤0.0001) in fatigue strength. An accumulative damage model was developed to characterize fatigue of the control and bur treated dentin as well as provide a model for fatigue life prediction. The damage models were derived as a function of number of loading cycles (N), and ratio of applied stress to ultimate strength (r). The developed models provide estimations for the initial state of damage, the state of damage during the life, as well as the damage accumulation rate for cyclic loading of dentin

  12. Three-dimensional analysis of cranial growth from 6 to 12 months of age.

    PubMed

    Meyer-Marcotty, P; Böhm, H; Linz, C; Kochel, J; Stellzig-Eisenhauer, A; Schweitzer, T

    2014-10-01

    The aim of this study was to generate three-dimensional data of the physiological growth of the infant's cranium in the significant growth phase from 6 to 12 months of age. In a longitudinal observational study non-invasive 3D data using an optical surface scanner were generated of the entire head of 52 Caucasian infants (27 females and 25 males) between the ages of 6 (T1) and 12 (T2) months. The circumference of the head increased by 6.51 per cent (from 43.50 to 46.33cm). Analysis of width and length showed that the head grows 2.84 per cent more in length, resulting in a decrease in the cranial index of 2.52 per cent (from 83.87 to 81.76 per cent). The highest increment observed was in the total volume of the cranium, with an increase of 18.76 per cent (from 1229.01 to 1459.57cm(3)). Comparison of the left and right sides of the head by measuring the diagonal symmetry difference showed a difference of only 0.37cm. Overall, the symmetry-related parameters showed an almost symmetric development of the cranium in infants. The findings should provide valuable information on physiological growth and development of the infant's cranium. Therefore the high growth rate of the cranium in the first year of life suggests that this period is a critical period in which the disruption of developmental processes may have long-lasting effects on the morphology of the cranium with a prognostically unfavourable effect of the further growth of the viscerocranium.

  13. Structural modeling of age specific fertility curves in Peninsular Malaysia: An approach of Lee Carter method

    NASA Astrophysics Data System (ADS)

    Hanafiah, Hazlenah; Jemain, Abdul Aziz

    2013-11-01

    In recent years, the study of fertility has been getting a lot of attention among research abroad following fear of deterioration of fertility led by the rapid economy development. Hence, this study examines the feasibility of developing fertility forecasts based on age structure. Lee Carter model (1992) is applied in this study as it is an established and widely used model in analysing demographic aspects. A singular value decomposition approach is incorporated with an ARIMA model to estimate age specific fertility rates in Peninsular Malaysia over the period 1958-2007. Residual plots is used to measure the goodness of fit of the model. Fertility index forecast using random walk drift is then utilised to predict the future age specific fertility. Results indicate that the proposed model provides a relatively good and reasonable data fitting. In addition, there is an apparent and continuous decline in age specific fertility curves in the next 10 years, particularly among mothers' in their early 20's and 40's. The study on the fertility is vital in order to maintain a balance between the population growth and the provision of facilities related resources.

  14. Mature and old-growth riparian forests: structure, dynamics, and effects on Adirondack stream habitats.

    PubMed

    Keeton, William S; Kraft, Clifford E; Warren, Dana R

    2007-04-01

    Riparian forests regulate linkages between terrestrial and aquatic ecosystems, yet relationships among riparian forest development, stand structure, and stream habitats are poorly understood in many temperate deciduous forest systems. Our research has (1) described structural attributes associated with old-growth riparian forests and (2) assessed linkages between these characteristics and in-stream habitat structure. The 19 study sites were located along predominantly first- and second-order streams in northern hardwood-conifer forests in the Adirondack Mountains of New York (U.S.A.). Sites were classified as mature forest (6 sites), mature with remnant old-growth trees (3 sites), and old-growth (10 sites). Forest-structure attributes were measured over stream channels and at varying distances from each bank. In-stream habitat features such as large woody debris (LWD), pools, and boulders were measured in each stream reach. Forest structure was examined in relation to stand age using multivariate techniques, ANOVA, and linear regression. We investigated linkages between forest structure and stream characteristics using similar methods, preceded by information-theoretic modeling (AIC). Old-growth riparian forest structure is more complex than that found in mature forests and exhibits significantly greater accumulations of aboveground tree biomass, both living and dead. In-stream LWD volumes were significantly (alpha = 0.05) greater at old-growth sites (200 m3/ha) compared to mature sites (34 m3/ha) and were strongly related to the basal area of adjacent forests. In-stream large-log densities correlated strongly with debris-dam densities. AIC models that included large-log density, debris-dam density, boulder density, and bankfull width had the most support for predicting pool density. There were higher proportions of LWD-formed pools relative to boulder-formed pools at old-growth sites as compared to mature sites. Old-growth riparian forests provide in

  15. 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

  16. Survival of enteric pathogens during butterhead lettuce growth: crop stage, leaf age, and irrigation.

    PubMed

    Van der Linden, Inge; Cottyn, Bart; Uyttendaele, Mieke; Vlaemynck, Geertrui; Heyndrickx, Marc; Maes, Martine

    2013-06-01

    The survival of Salmonella enterica serovar Thompson and Escherichia coli O157 was investigated on growing butterhead lettuce plants in the plant-growth chamber and greenhouse. All inoculation tests were made under conditions that approximate the greenhouse conditions for butterhead lettuce cultivation in Flanders (Belgium). The survival and proliferation of the pathogens on the leaves was determined at days 0, 4, and 8 after inoculation using standard plating techniques on selective medium. In the growth chamber, the extent to which both pathogens were able to multiply on the lettuce leaves was influenced by crop stage and leaf age. On young plants, the older leaves supported pathogen survival better. On nearly mature plants, pathogen population sizes were significantly higher on the old and young leaves compared with middle-aged leaves (p<0.001). In the greenhouse, the environmental regimen with high fluctuations in temperature and relative humidity was less conducive to the survival of E. coli O157, though its survival on nearly mature lettuce was enhanced by overhead irrigation. The moist conditions between the folded inner leaves are likely contributing to the survival of enteric pathogens in the lettuce head. Butterhead lettuce grown in greenhouses with a sprinkle irrigation system may present a potential health hazard when contaminated near harvest. Experimental design (growth chamber versus greenhouse) largely influences enteric pathogen behavior on growing lettuce plants.

  17. Drosophila Fip200 is an essential regulator of autophagy that attenuates both growth and aging

    PubMed Central

    Kim, Myungjin; Park, Hae Li; Park, Hwan-Woo; Ro, Seung-Hyun; Nam, Samuel G.; Reed, John M.; Guan, Jun-Lin; Lee, Jun Hee

    2013-01-01

    Autophagy-related 1 (Atg1)/Unc-51-like protein kinases (ULKs) are evolutionarily conserved proteins that play critical physiological roles in controlling autophagy, cell growth and neurodevelopment. RB1-inducible coiled-coil 1 (RB1CC1), also known as PTK2/FAK family-interacting protein of 200 kDa (FIP200) is a recently discovered binding partner of ULK1. Here we isolated the Drosophila RB1CC1/FIP200 homolog (Fip200/CG1347) and showed that it mediates Atg1-induced autophagy as a genetically downstream component in diverse physiological contexts. Fip200 loss-of-function mutants experienced severe mobility loss associated with neuronal autophagy defects and neurodegeneration. The Fip200 mutants were also devoid of both developmental and starvation-induced autophagy in salivary gland and fat body, while having no defects in axonal transport and projection in developing neurons. Interestingly, moderate downregulation of Fip200 accelerated both developmental growth and aging, accompanied by target of rapamycin (Tor) signaling upregulation. These results suggest that Fip200 is a critical downstream component of Atg1 and specifically mediates Atg1’s autophagy-, aging- and growth-regulating functions. PMID:23819996

  18. Age matters: the effects of volatile organic compounds emitted by Trichoderma atroviride on plant growth.

    PubMed

    Lee, Samantha; Hung, Richard; Yap, Melanie; Bennett, Joan W

    2015-06-01

    Studying the effects of microbial volatile organic compounds (VOCs) on plant growth is challenging because the production of volatiles depends on many environmental factors. Adding to this complexity, the method of volatile exposure itself can lead to different responses in plants and may account for some of the contrasting results. In this work, we present an improved experimental design, a plate-within-a-plate method, to study the effects of VOCs produced by filamentous fungi. We demonstrate that the plant growth response to VOCs is dependent on the age of the plant and fungal cultures. Plants exposed to volatiles emitted by 5-day-old Trichoderma atroviride for 14 days exhibited inhibition, while plants exposed to other exposure conditions had growth promotion or no significant change. Using GC-MS, we compared fungal volatile emission of 5-day-old and 14-day-old T. atroviride. As the fungi aged, a few compounds were no longer detected, but 24 new compounds were discovered.

  19. Age, growth, and gonadal characteristics of adult bighead carp, Hypophthalmichthys nobilis, in the lower Missouri River

    USGS Publications Warehouse

    Schrank, S.J.; Guy, C.S.

    2002-01-01

    Bighead carp were introduced into Arkansas in 1973 to improve water clarity in production ponds. Bighead carp subsequently escaped aquaculture facilities in the early 1980's and dispersed into the Mississippi and Missouri rivers. The first documentation of bighead carp reproduction in the Mississippi River system was in 1989. The population has increased in the Missouri River as is evident in their increased proportion in the commercial harvest since 1990. The effect of this exotic planktivore on native ecosystems of the U.S. has not been examined. Basic biological data on bighead carp Hypophthalmichthys nobilis in the Missouri River are needed to predict potential ecological problems and provide a foundation for manipulative studies. The objectives of this study were to assess age, growth, and gonadal characteristics of bighead carp in the Missouri River. Adult bighead carp in our sample varied from age 3 to age 7 and length varied from 475 to 1050 mm. There was a large variation in length at age, and overall bighead carp exhibited fast growth. For example, mean back-calculated length at age 3 was 556 mm. The sample was dominated by bighead carp from the 1994 year class. There was no difference in gonad development (i.e., gonadal somatic index, egg diameter) between winter and spring samples. Length of male bighead carp and GSI were not significantly correlated; however, females exhibited a positive linear relationship between length and GSI. In each ovary, egg diameter frequencies exhibited a bimodal distribution, indicating protracted spawning. Mean fecundity was 226 213, with a maximum fecundity of 769 964. Bighead carp in the Missouri River have similar life history characteristics to Asian and European populations. They have become well established in the Missouri River and it is likely that dispersal and population density will increase.

  20. Micro-structured surfaces for algal biofilm growth

    NASA Astrophysics Data System (ADS)

    Sathananthan, Suthamathy; Genin, Scott N.; Aitchison, J. Stewart; Allen, D. Grant

    2013-12-01

    It is well known that cells respond to structured surface cues that are on the micro/nanometer scale. Tissue engineering and bio-fouling fields have utilized the semiconductor device fabrication processes to make micro- and nanometer patterned surfaces to study animal cell tissue formation and to prevent algae attachment on marine surfaces respectively. In this paper we describe the use of micro-structured surfaces to study the attachment and growth of algal films. This paper gives an overview of how micro-structured surfaces are made for this purpose, how they are incorporated into a photo bioreactor and how this patterning influences the growth of an algal biofilm. Our results suggest that surface patterning with deeper V-groove patterns that are of the same size scale as the algal species has resulted in higher biomass productivity giving them a chance to embed and attach on the slope and flat surfaces whereas shallower size grooves and completely flat surfaces did not show this trend.

  1. Separating the effects of intra- and interspecific age-structured interactions in an experimental fish assemblage

    USGS Publications Warehouse

    Taylor, R.C.; Trexler, J.C.; Loftus, W.F.

    2001-01-01

    We documented patterns of age-structured biotic interactions in four mesocosm experiments with an assemblage of three species of co-occurring fishes from the Florida Everglades, the eastern mosquitofish (Gambusia holbrooki), sailfin molly (Poecilia latipinna), and bluefin killifish (Lucania goodei). These species were chosen based on their high abundance and overlapping diets. Juvenile mosquitofish and sailfin mollies, at a range of densities matching field estimates, were maintained in the presence of adult mosquitofish, sailfin mollies, and bluefin killifish to test for effects of competition and predation on juvenile survival and growth. The mesocosms held 1,200 1 of water and all conditions were set to simulate those in Shark River Slough, Everglades National Park (ENP), USA. We placed floating mats of periphyton and bladderwort in each tank in standard volumes that matched field values to provide cover and to introduce invertebrate prey. Of 15 possible intra- and interspecific age-structured interactions, we found 7 to be present at the densities of these fish found in Shark River Slough marshes. Predation by adult mosquitofish on juvenile fish, including conspecifics, was the strongest effect observed. We also observed growth limitation in mosquitofish and sailfin molly juveniles from intra- and interspecific competition. When maintained at high densities, juvenile mosquitofish changed their diets to include more cladocerans and fewer chironomid larvae relative to low densities. We estimated size-specific gape limitation by adult mosquitofish when consuming juvenile mosquitofish and sailfin mollies. At high field densities, intraspecific competition might prolong the time period when juveniles are vulnerable to predation by adult mosquitofish. These results suggest that path analysis, or other techniques used to document food-web interactions, must include age-specific roles of these fishes.

  2. Consumptive and nonconsumptive effects of cannibalism in fluctuating age-structured populations.

    PubMed

    Wissinger, Scott A; Whiteman, Howard H; Denoël, Mathieu; Mumford, Miranda L; Aubee, Catherine B

    2010-02-01

    Theory and empirical studies suggest that cannibalism in age-structured populations can regulate recruitment depending on the intensity of intraspecific competition between cannibals and victims and the nature of the cannibalism window, i.e., which size classes interact as cannibals and victims. Here we report on a series of experiments that quantify that window for age-structured populations of salamander larvae and paedomorphic adults. We determined body size limits on cannibalism in microcosms and then the consumptive and nonconsumptive (injuries, foraging and activity, diet, growth) effects on victims in mesocosms with seminatural levels of habitat complexity and alternative prey. We found that cannibalism by the largest size classes (paedomorphs and > or = age 3+ yr larvae) occurs mainly on young-of-the-year (YOY) victims. Surviving YOY and other small larvae had increased injuries, reduced activity levels, and reduced growth rates in the presence of cannibals. Data on YOY survival in an experiment in which we manipulated the density of paedomorphs combined with historical data on the number of cannibals in natural populations indicate that dominant cohorts of paedomorphs can cause observed recruitment failures. Dietary data indicate that ontogenetic shifts in diet should preclude strong intraspecific competition between YOY and cannibals in this species. Thus our results are consistent with previous empirical and theoretical work that suggests that recruitment regulation by cannibalism is most likely when YOY are vulnerable to cannibalism but have low dietary overlap with cannibals. Understanding the role of cannibalism in regulating recruitment in salamander populations is timely, given the widespread occurrences of amphibian decline. Previous studies have focused on extrinsic (including anthropogenic) factors that affect amphibian population dynamics, whereas the data presented here combined with long-term field observations suggest the potential for

  3. Random regression model of growth during the first three months of age in Spanish Merino sheep.

    PubMed

    Molina, A; Menéndez-Buxadera, A; Valera, M; Serradilla, J M

    2007-11-01

    A total of 88,727 individual BW records of Spanish Merino lambs, obtained from 30,214 animals between 2 and 92 d of age, were analyzed using a random regression model (RRM). These animals were progeny of 546 rams and 15,586 ewes raised in 30 flocks, between 1992 and 2002, with a total of 45,941 animals in the pedigree. The contemporary groups (animals of the same flock, year, and season, with 452 levels), the lambing number (11 levels), the combination sex of lambs with type of litter (4 levels), and a fixed regression coefficient of age on BW were included as fixed effects. A total of 7 RRM were compared, and the best fit was obtained for a model of order 3 for the direct and maternal genetic effects and for the individual permanent environmental effect. For the maternal permanent environmental effect the best model had an order 2. The residual variance was assumed to be heterogeneous with 10 age classes; the covariance between both genetic effects was included. According to the results of the selected RRM, the heritability for both genetic effects (h(a)2 and h(m)2) increased with age, with estimates of 0.123 to 0.186 for h(a)2 and of 0.059 to 0.108 for h(m)2. The correlations between direct and genetic maternal effects were -0.619 to -0.387 during the first 45 d of age and decreased as age increased, until reaching values from -0.366 to -0.275 between 45 to 75 d of age. Important changes in ranking of the animals were found based on the breeding value estimation with the current method and with the random regression procedure. The use of RRM to analyze the genetic trajectory of growth in this population of Merino sheep is highly recommended.

  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. Protocols and programs for high-throughput growth and aging phenotyping in yeast.

    PubMed

    Jung, Paul P; Christian, Nils; Kay, Daniel P; Skupin, Alexander; Linster, Carole L

    2015-01-01

    In microorganisms, and more particularly in yeasts, a standard phenotyping approach consists in the analysis of fitness by growth rate determination in different conditions. One growth assay that combines high throughput with high resolution involves the generation of growth curves from 96-well plate microcultivations in thermostated and shaking plate readers. To push the throughput of this method to the next level, we have adapted it in this study to the use of 384-well plates. The values of the extracted growth parameters (lag time, doubling time and yield of biomass) correlated well between experiments carried out in 384-well plates as compared to 96-well plates or batch cultures, validating the higher-throughput approach for phenotypic screens. The method is not restricted to the use of the budding yeast Saccharomyces cerevisiae, as shown by consistent results for other species selected from the Hemiascomycete class. Furthermore, we used the 384-well plate microcultivations to develop and validate a higher-throughput assay for yeast Chronological Life Span (CLS), a parameter that is still commonly determined by a cumbersome method based on counting "Colony Forming Units". To accelerate analysis of the large datasets generated by the described growth and aging assays, we developed the freely available software tools GATHODE and CATHODE. These tools allow for semi-automatic determination of growth parameters and CLS behavior from typical plate reader output files. The described protocols and programs will increase the time- and cost-efficiency of a number of yeast-based systems genetics experiments as well as various types of screens.

  6. Protocols and Programs for High-Throughput Growth and Aging Phenotyping in Yeast

    PubMed Central

    Jung, Paul P.; Christian, Nils; Kay, Daniel P.; Skupin, Alexander; Linster, Carole L.

    2015-01-01

    In microorganisms, and more particularly in yeasts, a standard phenotyping approach consists in the analysis of fitness by growth rate determination in different conditions. One growth assay that combines high throughput with high resolution involves the generation of growth curves from 96-well plate microcultivations in thermostated and shaking plate readers. To push the throughput of this method to the next level, we have adapted it in this study to the use of 384-well plates. The values of the extracted growth parameters (lag time, doubling time and yield of biomass) correlated well between experiments carried out in 384-well plates as compared to 96-well plates or batch cultures, validating the higher-throughput approach for phenotypic screens. The method is not restricted to the use of the budding yeast Saccharomyces cerevisiae, as shown by consistent results for other species selected from the Hemiascomycete class. Furthermore, we used the 384-well plate microcultivations to develop and validate a higher-throughput assay for yeast Chronological Life Span (CLS), a parameter that is still commonly determined by a cumbersome method based on counting “Colony Forming Units”. To accelerate analysis of the large datasets generated by the described growth and aging assays, we developed the freely available software tools GATHODE and CATHODE. These tools allow for semi-automatic determination of growth parameters and CLS behavior from typical plate reader output files. The described protocols and programs will increase the time- and cost-efficiency of a number of yeast-based systems genetics experiments as well as various types of screens. PMID:25822370

  7. Age-related changes in rat myocardium involve altered capacities of glycosaminoglycans to potentiate growth factor functions and heparan sulfate-altered sulfation.

    PubMed

    Huynh, Minh Bao; Morin, Christophe; Carpentier, Gilles; Garcia-Filipe, Stephanie; Talhas-Perret, Sofia; Barbier-Chassefière, Véronique; van Kuppevelt, Toin H; Martelly, Isabelle; Albanese, Patricia; Papy-Garcia, Dulce

    2012-03-30

    Glycosaminoglycans (GAGs) are essential components of the extracellular matrix, the natural environment from which cell behavior is regulated by a number or tissue homeostasis guarantors including growth factors. Because most heparin-binding growth factor activities are regulated by GAGs, structural and functional alterations of these polysaccharides may consequently affect the integrity of tissues during critical physiological and pathological processes. Here, we investigated whether the aging process can induce changes in the myocardial GAG composition in rats and whether these changes can affect the activities of particular heparin-binding growth factors known to sustain cardiac tissue integrity. Our results showed an age-dependent increase of GAG levels in the left ventricle. Biochemical and immunohistological studies pointed out heparan sulfates (HS) as the GAG species that increased with age. ELISA-based competition assays showed altered capacities of the aged myocardial GAGs to bind FGF-1, FGF-2, and VEGF but not HB EGF. Mitogenic assays in cultured cells showed an age-dependent decrease of the elderly GAG capacities to potentiate FGF-2 whereas the potentiating effect on VEGF(165) was increased, as confirmed by augmented angiogenic cell proliferation in Matrigel plugs. Moreover, HS disaccharide analysis showed considerably altered 6-O-sulfation with modest changes in N- and 2-O-sulfations. Together, these findings suggest a physiological significance of HS structural and functional alterations during aging. This can be associated with an age-dependent decline of the extracellular matrix capacity to efficiently modulate not only the activity of resident or therapeutic growth factors but also the homing of resident or therapeutic cells.

  8. Age and growth of the gulf toadfish Opsanus beta based on otolith increment analysis.

    PubMed

    Malca, E; Barimo, J F; Serafy, J E; Walsh, P J

    2009-11-01

    In the present study, sagittal otoliths of confirmed male and female specimens of the gulf toadfish Opsanus beta that were collected monthly over the course of a year from Biscayne Bay, Florida, U.S.A. were analysed. The timing and frequency of O. beta spawning seasons are reported by examination of the gonado-somatic index. The estimated ages of males and females ranged from <1 year to 6 and 5 years, respectively. Strong sexual dimorphism in growth was apparent with von Bertalanffy parameter estimates for males of Linfinity=393.8 mm, K=0.30, t0=0.36 and females of Linfinity=201.1 mm, K=0.79, t0=0.47. Comparison with previously published growth trajectories of the more northerly distributed conspecific Opsanus tau showed that O. beta males had a higher growth rate. Female O. beta and O. tau growth trajectories appear similar, with an indication that the former becomes asymptotic at least a year before the latter. Results are discussed in the context of temperature regimes, reproductive energy allocation and waste urea excretion in the two species.

  9. Age and growth of the kiyi, Leucichthys kiyi Koelz, in Lake Michigan

    USGS Publications Warehouse

    Deason, Hilary J.; Hile, Ralph

    1947-01-01

    Ages were determined and individual growth histories were calculated from the examination and measurement of the scales of 1,649 kiyis captured at seven localities in Lake Michigan in 1931 and 1932. The numbers of individuals employed for the investigation of other phases of the life history (such as length-frequency distributions, length-weight relationship, and sex ratio) varied according to the amount of data available or required. Age-group IV was dominant in the 1931 collections from Racine, Port Washington, and Kewaunee, Wisconsin, and age-group V dominated the 1932 samples from the Fox Islands and from three localities southward of Manistique, Michigan. A trend was noticeable toward an increase in average age from south to north. Among the explanations suggested for the observed differences in age composition were: Variation with latitude in the natural span of life; differences in fishing intensity; fluctuations in the strength of year classes (to account possibly for the shift in the dominant age group from 1931 to 1932). The oldest male kiyi belonged to the VII group and the oldest female was a member of the X group. The possible distorting effects of such factors as gear selection traceable to differences in the mesh sizes of nets fished in 1931 and 1932, selection by nets on the basis of the condition (K) of the fish, and local variations in fishing intensity and hence in the selective destruction of rapidly growing individuals in the fishery were held to be sufficiently great to render doubtful the significance of most of the observed local differences in growth rate. Kiyis from all samples were combined to determine the general growth in length. The growth in weight of the Fox Islands fish, however, was considered separately as these fish were consistently lighter than kiyis of corresponding length from other localities. The Lake Michigan kiyi grows slowly, with the females growing slightly more rapidly than the males. The grand average calculated

  10. The first description of oarfish Regalecus glesne (Regalecus russellii Cuvier 1816) ageing structures

    USGS Publications Warehouse

    Midway, S.R.; Wagner, Tyler

    2016-01-01

    Despite being a large, conspicuous teleost with a worldwide tropical and temperate distribution, the giant oarfish Regalecus spp. remain very rare fish species in terms of scientific sampling. Subsequently, very little biological information is known about Regalecus spp. and almost nothing has been concluded in the field of age and growth (Roberts, 2012). No studies of otoliths or temporal (annual) markings on any hard structures have been reported, and to our knowledge otoliths have never been recovered from any specimens (Tyson Roberts, personal communication),although a few texts do provide illustrations of Regalecus sp. otoliths (Lin and Chang, 2012; Nolf, 2013). Further inferential difficulty comes from the fact that age and growth studies of any Lampridiforme species are rare. Lampris guttatus is perhaps the only Lampridiforme species for which any biological information has been reported(Francis et al., 2004), which stems from the species commercial value. In order to begin understanding any species (for later purposes of management, conservation, etc.), basic biological information is needed. In the present study, we examine not only the first Regalecus russellii otolith, but provide suggestions toward future work that should direct data collection that can be used to generate basic biological information for this species.

  11. Ra isotopes in trees: Their application to the estimation of heartwood growth rates and tree ages

    NASA Astrophysics Data System (ADS)

    Hancock, Gary J.; Murray, Andrew S.; Brunskill, Gregg J.; Argent, Robert M.

    2006-12-01

    The difficulty in estimating growth rates and ages of tropical and warm-temperate tree species is well known. However, this information has many important environmental applications, including the proper management of native forests and calculating uptake and release of atmospheric carbon. We report the activities of Ra isotopes in the heartwood, sapwood and leaves of six tree species, and use the radial distribution of the 228Ra/226Ra activity ratio in the stem of the tree to estimate the rate of accretion of heartwood. A model is presented in which dissolved Ra in groundwater is taken up by tree roots, translocated to sapwood in a chemically mobile (ion-exchangeable) form, and rendered immobile as it is transferred to heartwood. Uptake of 232Th and 230Th (the parents of 228Ra and 226Ra) is negligible. The rate of heartwood accretion is determined from the radioactive decay of 228Ra (half-life 5.8 years) relative to long-lived 226Ra (half-life 1600 years), and is relevant to growth periods of up to 50 years. By extrapolating the heartwood accretion rate to the entire tree ring record the method also appears to provide realistic estimates of tree age. Eight trees were studied (three of known age, 72, 66 and 35 years), including three Australian hardwood eucalypt species, two mangrove species, and a softwood pine (P. radiata). The method indicates that the rate of growth ring formation is species and climate dependent, varying from 0.7 rings yr-1 for a river red gum (E. camaldulensis) to around 3 rings yr-1 for a tropical mangrove (X. mekongensis).

  12. Atomic and electronic structure of twin growth defects in magnetite

    PubMed Central

    Gilks, Daniel; Nedelkoski, Zlatko; Lari, Leonardo; Kuerbanjiang, Balati; Matsuzaki, Kosuke; Susaki, Tomofumi; Kepaptsoglou, Demie; Ramasse, Quentin; Evans, Richard; McKenna, Keith; Lazarov, Vlado K.

    2016-01-01

    We report the existence of a stable twin defect in Fe3O4 thin films. By using aberration corrected scanning transmission electron microscopy and spectroscopy the atomic structure of the twin boundary has been determined. The boundary is confined to the (111) growth plane and it is non-stoichiometric due to a missing Fe octahedral plane. By first principles calculations we show that the local atomic structural configuration of the twin boundary does not change the nature of the superexchange interactions between the two Fe sublattices across the twin grain boundary. Besides decreasing the half-metallic band gap at the boundary the altered atomic stacking at the boundary does not change the overall ferromagnetic (FM) coupling between the grains. PMID:26876049

  13. Atomic and electronic structure of twin growth defects in magnetite

    NASA Astrophysics Data System (ADS)

    Gilks, Daniel; Nedelkoski, Zlatko; Lari, Leonardo; Kuerbanjiang, Balati; Matsuzaki, Kosuke; Susaki, Tomofumi; Kepaptsoglou, Demie; Ramasse, Quentin; Evans, Richard; McKenna, Keith; Lazarov, Vlado K.

    2016-02-01

    We report the existence of a stable twin defect in Fe3O4 thin films. By using aberration corrected scanning transmission electron microscopy and spectroscopy the atomic structure of the twin boundary has been determined. The boundary is confined to the (111) growth plane and it is non-stoichiometric due to a missing Fe octahedral plane. By first principles calculations we show that the local atomic structural configuration of the twin boundary does not change the nature of the superexchange interactions between the two Fe sublattices across the twin grain boundary. Besides decreasing the half-metallic band gap at the boundary the altered atomic stacking at the boundary does not change the overall ferromagnetic (FM) coupling between the grains.

  14. Atomic and electronic structure of twin growth defects in magnetite.

    PubMed

    Gilks, Daniel; Nedelkoski, Zlatko; Lari, Leonardo; Kuerbanjiang, Balati; Matsuzaki, Kosuke; Susaki, Tomofumi; Kepaptsoglou, Demie; Ramasse, Quentin; Evans, Richard; McKenna, Keith; Lazarov, Vlado K

    2016-02-15

    We report the existence of a stable twin defect in Fe3O4 thin films. By using aberration corrected scanning transmission electron microscopy and spectroscopy the atomic structure of the twin boundary has been determined. The boundary is confined to the (111) growth plane and it is non-stoichiometric due to a missing Fe octahedral plane. By first principles calculations we show that the local atomic structural configuration of the twin boundary does not change the nature of the superexchange interactions between the two Fe sublattices across the twin grain boundary. Besides decreasing the half-metallic band gap at the boundary the altered atomic stacking at the boundary does not change the overall ferromagnetic (FM) coupling between the grains.

  15. The linear growth of structure in the Rh = ct universe

    NASA Astrophysics Data System (ADS)

    Melia, Fulvio

    2017-01-01

    We use recently published redshift space distortion measurements of the cosmological growth rate, fσ8(z), to examine whether the linear evolution of perturbations in the Rh = ct cosmology is consistent with the observed development of large-scale structure. We find that these observations favour Rh = ct over the version of Λ cold dark matter (ΛCDM) optimized with the joint analysis of Planck and linear growth rate data, particularly in the redshift range 0 < z < 1, where a significant curvature in the functional form of fσ8(z) predicted by the standard model-but not by Rh = ct-is absent in the data. When ΛCDM is optimized using solely the growth rate measurements; however, the two models fit the observations equally well though, in this case, the low-redshift measurements find a lower value for the fluctuation amplitude than is expected in Planck ΛCDM. Our results strongly affirm the need for more precise measurements of fσ8(z) at all redshifts, but especially at z < 1.

  16. Growth Rate and Relocation Movements of Common Nighthawk (Chordeiles minor) Nestlings in Relation to Age

    USGS Publications Warehouse

    Kramer, Gunnar R.; Chalfoun, Anna D.

    2012-01-01

    Relocation by dependent young is a survival strategy that occurs among a wide range of taxa. The Common Nighthawk (Chordeiles minor) lays its eggs on bare substrate and, once hatched, nestlings may relocate to new sites daily. We located and monitored eight Common Nighthawk nests in Grand Teton National Park, Wyoming, quantified inter-use-site distances in relation to nestling age, and calculated a nestling growth rate curve. Common Nighthawk nestlings grow in a nearly linear fashion. Nestlings moved up to 48 m in a single day and larger, older nestlings tended to move greater distances between daily use-sites.

  17. Age-dependent role of steroids in the regulation of growth of the hen follicular wall

    PubMed Central

    2010-01-01

    Background The ovaries are the primary targets of senescence effects in mammalian and avian species. In the present study, relationships between reproductive aging, sex steroids and the growth pattern of the pre-ovulatory follicle wall were investigated using young hens with long clutch (YLC), old hens with long clutch (OLC), old hens with short clutch (OSC), and old hens with interrupted long clutch (OILC). Methods Experiment 1: Hens were sacrificed 1.5 and 14.5 h after ovulation. Experiment 2: YLC and OILC hens were sacrificed 3.5 h after treatments with LH and/or aminoglutethimide (AG), an inhibitor of steroid synthesis. Volumes of pre-ovulatory follicles (F1-F5) and plasma concentrations of ovarian steroids were determined. Experiment 3: Granulosa and theca cells from F3 follicles of OSC and/or YLC hens were exposed in vitro to estradiol-17beta (E2), testosterone (T) and LH and the proliferative activity of the cells was examined using CellTiter 96 Aqueous One Solution Assay. Results In YLC and OLC groups, the total volume of F1-F5 follicles rose between 1.5 and 14.5 h after ovulation (P < 0.01), negatively correlating with the plasma level of E2 (P < 0.01). There was no growth of pre-ovulatory follicles in the middle of the ovulatory cycle in the OSC group, with a positive correlation being present between E2 and the follicular volume (P < 0.05). In young hens, AG caused a rise in the total follicular volume. This rise was associated with a fall in E2 (r = -0.54, P < 0.05). E2 enhanced proliferation of granulosa cells from YLC and OSC groups. The proliferative activity of granulosa and theca cells of YLC hens depended on the interaction between T and LH (P < 0.01). Conclusions These data indicate for the first time that the growth pattern of pre-ovulatory follicles during the ovulatory cycle changes in the course of reproductive aging. E2 seems to play a dual role in this adjustment; it stimulates the growth of the follicular wall in reproductive aged hens

  18. Age determinations and growth rates of Pacific ferromanganese deposits using strontium isotopes

    USGS Publications Warehouse

    Ingram, B.L.; Hein, J.R.; Farmer, G.L.

    1990-01-01

    87Sr 86Sr ratios, trace element and REE compositions, and textural characteristics were determined for three hydrogenetic Fe-Mn crusts, one hydrothermal deposit, and two mixed hydrothermalhydrogenetic crusts from the Pacific. The Sr isotope data are compared to the Sr seawater curve for the Cenozoic to determine the ages and growth rates of the crusts. The 87Sr 86Sr in the crusts does not increase monotonically with depth as expected if the Sr were solely derived from seawater and perfectly preserved since deposition. This indicates post-depositional exchange of Sr or heterogeneous sources for the Sr originally contained in the crusts. Textures of hydrogenetic crusts generally correlate with Sr isotopic variations. The highest porosity intervals commonly exhibit the highest 87Sr 86Sr ratios, indicating exchange with younger seawater. Intervals with the lowest porosity commonly have lower 87Sr 86Sr and may preserve the original Sr isotopic ratios. Minimum ages of crust growth inception were calculated from dense, low porosity intervals. Growth of the hydrogenetic crusts began at or after 23 Ma, although their substrates are Cretaceous. Estimated average growth rates of the three hydrogenetic crusts vary between 0.9 and 2.7 mm/Ma, consistent with published rates determined by other techniques. Within the Marshall Islands crust, growth rates for individual layers varied greatly between 1.0 and 5.4 mm/Ma. For one crust, very low 87Sr 86Sr ratios occurred in detrital-rich intervals. Hydrothermal Fe-Mn oxide from the active Lau Basin back-arc spreading axis (Valu Fa Ridge) has an 87Sr 86Sr ratio with a predominantly seawater signature ( 87Sr 86Sr 0.709196), indicating a maximum age of 0.9 Ma. One crust from an off-axis seamount west of Gorda Ridge may have begun precipitating hydrogenetically at 0.5 Ma (0.709211), and had increasing hydrothermal or volcanic input in the top half of the crust, indicated by a significantly lower 87Sr 86Sr ratio (0.709052). ?? 1990.

  19. Family Structure and the Timing of Transitions from 70 to 103 Years of Age.

    ERIC Educational Resources Information Center

    Johnson, Colleen L.; Troll, Lillian

    1996-01-01

    Using a cross-sectional analysis of 250 white individuals, 70-103 years of age, this article questions whether a vertical family structure is found with increasing age. Findings indicate, among other things, that at least until age 90 the proportion of individuals with a vertical family structure with four generations never exceeds the numbers of…

  20. 75 FR 24930 - Fort Bliss (Texas) Army Growth and Force Structure Realignment Final Environmental Impact...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-06

    ... Department of the Army Fort Bliss (Texas) Army Growth and Force Structure Realignment Final Environmental... Department of the Army announces the availability of the Fort Bliss Army Growth and Force Structure... improvements at Fort Bliss to support Army growth and force structure realignment. The FEIS tiers from...

  1. Use of World Health Organization and CDC growth charts for children aged 0-59 months in the United States.

    PubMed

    Grummer-Strawn, Laurence M; Reinold, Chris; Krebs, Nancy F

    2010-09-10

    In April 2006, the World Health Organization (WHO) released new international growth charts for children aged 0-59 months. Similar to the 2000 CDC growth charts, these charts describe weight for age, length (or stature) for age, weight for length (or stature), and body mass index for age. Whereas the WHO charts are growth standards, describing the growth of healthy children in optimal conditions, the CDC charts are a growth reference, describing how certain children grew in a particular place and time. However, in practice, clinicians use growth charts as standards rather than references. In 2006, CDC, the National Institutes of Health, and the American Academy of Pediatrics convened an expert panel to review scientific evidence and discuss the potential use of the new WHO growth charts in clinical settings in the United States. On the basis of input from this expert panel, CDC recommends that clinicians in the United States use the 2006 WHO international growth charts, rather than the CDC growth charts, for children aged <24 months (available at https://www.cdc.gov/growthcharts). The CDC growth charts should continue to be used for the assessment of growth in persons aged 2--19 years. The recommendation to use the 2006 WHO international growth charts for children aged <24 months is based on several considerations, including the recognition that breastfeeding is the recommended standard for infant feeding. In the WHO charts, the healthy breastfed infant is intended to be the standard against which all other infants are compared; 100% of the reference population of infants were breastfed for 12 months and were predominantly breastfed for at least 4 months. When using the WHO growth charts to screen for possible abnormal or unhealthy growth, use of the 2.3rd and 97.7th percentiles (or ±2 standard deviations) are recommended, rather than the 5th and 95th percentiles. Clinicians should be aware that fewer U.S. children will be identified as underweight using the WHO

  2. Age, growth, and natural mortality of schoolmaster (Lutjanus apodus) from the southeastern United States

    PubMed Central

    Burton, Michael L.; Myers, Amanda R.

    2016-01-01

    Ages of schoolmaster (n = 136) from the southeastern Florida coast from 1981–2015 were determined using sectioned sagittal otoliths. Opaque zones were annular, forming March–July (peaking in May–June). Schoolmaster ranged in age from 1–42 years; the largest fish measured 505 mm total length (TL) and was 19 years old. The oldest fish measured 440 mm TL. Estimated body size relationships for schoolmaster were: W = 9.26 × 10−6 TL3.11 (n = 256, r2 = 0.95); W = 2.13 × 10−5 FL2.99 (n = 161, r2 = 0.95); TL = 1.03 FL + 10.36 (n = 143, r2 = 0.99); and FL = 0.96 TL − 8.41 (n = 143, r2 = 0.99), where W = whole weight in g, FL = fork length in mm, and TL in mm. The fitted von Bertalanffy growth equation was: Lt = 482 (1 − e−0.12(t+2.79)) (n = 136). Based on published life history relationships, a point estimate of natural mortality for schoolmaster was M = 0.10, while age-specific estimates of M ranged from 1.57–0.18 for ages 1–42. PMID:27761332

  3. On the growth and internal structure of the human lens.

    PubMed

    Augusteyn, Robert C

    2010-06-01

    Growth of the human lens and the development of its internal features are examined using in vivo and in vitro observations on dimensions, weights, cell sizes, protein gradients and other properties. In vitro studies have shown that human lens growth is biphasic, asymptotic until just after birth and linear for most of postnatal life. This generates two distinct compartments, the prenatal and the postnatal. The prenatal growth mode leads to the formation of an adult nuclear core of fixed dimensions and the postnatal, to an ever-expanding cortex. The nuclear core and the cortex have different properties and can readily be physically separated. Communication and adhesion between the compartments is poor in older lenses. In vivo slit lamp examination reveals several zones of optical discontinuity in the lens. Different nomenclatures have been used to describe these, with the most common recognizing the embryonic, foetal, juvenile and adult nuclei as well as the cortex and outer cortex. Implicit in this nomenclature is the idea that the nuclear zones were generated at defined periods of development and growth. This review examines the relationship between the two compartments observed in vitro and the internal structures revealed by slit lamp photography. Defining the relationship is not as simple as it might seem because of remodeling and cell compaction which take place, mostly in the first 20 years of postnatal life. In addition, different investigators use different nomenclatures when describing the same regions of the lens. From a consideration of the dimensions, the dry mass contents and the protein distributions in the lens and in the various zones, it can be concluded that the juvenile nucleus and the layers contained within it, as well as most of the adult nucleus, were actually produced during prenatal life and the adult nucleus was completed within 3 months after birth, in the final stages of the prenatal growth mode. Further postnatal growth takes place

  4. On the growth and internal structure of the human lens

    PubMed Central

    Augusteyn, Robert C

    2010-01-01

    Growth of the human lens and the development of its internal features are examined using in vivo and in vitro observations on dimensions, weights, cell sizes, protein gradients and other properties. In vitro studies have shown that human lens growth is biphasic, asymptotic until just after birth and linear for most of postnatal life. This generates two distinct compartments, the prenatal and the postnatal. The prenatal growth mode leads to the formation of an adult nuclear core of fixed dimensions and the postnatal, to an ever-expanding cortex. The nuclear core and the cortex have different properties and can readily be physically separated. Communication and adhesion between the compartments is poor in older lenses. In vivo slit lamp examination reveals several zones of optical discontinuity in the lens. Different nomenclatures have been used to describe these, with the most common recognizing the embryonic, foetal, juvenile and adult nuclei as well as the cortex and outer cortex. Implicit in this nomenclature is the idea that the nuclear zones were generated at defined periods of development and growth. This review examines the relationship between the two compartments observed in vitro and the internal structures revealed by slit lamp photography. Defining the relationship is not as simple as it might seem because of remodeling and cell compaction which take place, mostly in the first 20 years of postnatal life. In addition, different investigators use different nomenclatures when describing the same regions of the lens. From a consideration of the dimensions, the dry mass contents and the protein distributions in the lens and in the various zones, it can be concluded that the juvenile nucleus and the layers contained within it, as well as most of the adult nucleus, were actually produced during prenatal life and the adult nucleus was completed within 3 months after birth, in the final stages of the prenatal growth mode. Further postnatal growth takes place

  5. Plasma Astrophysics - Cosmology and the Growth of Cosmic Structure

    SciTech Connect

    Mushotzky, Richard

    2007-08-02

    I will present some of the ways that x-ray spectroscopy can be utilized to determine cosmological parameters focusing on 5 methods: the gas fraction in clusters, the use of the Sunyaev-Zeldovich effect, the detection of resonance scattering in clusters, the use of resonance absorption and emission in background sources and the growth of structure. All of these techniques except the S-Z effect rely heavily on high resolution x-ray spectroscopy and require the next generation of x-ray spectroscopic missions such as Constellation-X. The promise of these techniques is great and they have the potential for precision cosmology with errors similar to those of other precision techniques such as type Ia supernova. If time permits I will also talk about how we can learn about how active galaxies strongly influence the growth of cosmic structure and how broad band high resolution x-ray spectra are necessary to measure the effects of AGN and how much energy they input into the universe and the role of new atomic physics calculations in interpreting these results. A related discussion can be found in a previously published manuscript.

  6. Crystalline structure-dependent growth of bimetallic nanostructures.

    PubMed

    Li, Qian; Jiang, Ruibin; Ming, Tian; Fang, Caihong; Wang, Jianfang

    2012-11-21

    Morphological control of multimetallic nanostructures is crucial for obtaining shape-dependent physical and chemical properties. Up to date, control of the shapes of multimetallic nanostructures has remained largely empirical. Multimetallic nanostructures have been produced mostly through seed-mediated growth. Understanding the role played by starting nanocrystal seeds can help in controlling the shape and in turn the plasmonic and catalytic properties of multimetallic nanostructures. In this work, we have studied the effect of the crystalline structure and shape of Au nanocrystal seeds on the morphology of the resultant bimetallic nanostructures. Single-crystalline Au nanorods, multiply twinned Au nanorods, and multiply twinned Au nanobipyramids were employed as the starting seeds. Both silver and palladium exhibit highly preferential growth on the side surfaces of the single-crystalline Au nanorods, giving rise to bimetallic cuboids, whereas they prefer to grow at the ends of the multiply twinned Au nanorods and nanobipyramids, giving rise to bimetallic nanorods. These results indicate that the morphology of the bimetallic nanostructures is highly dependent on the crystalline structure of the Au nanocrystal seeds. Our results will be useful for guiding the preparation of multimetallic nanostructures with desired shapes and therefore plasmonic properties for various plasmon-based applications.

  7. Structural basis for agonism and antagonism of hepatocyte growth factor

    SciTech Connect

    Tolbert, W. David; Daugherty-Holtrop, Jennifer; Gherardi, Ermanno; Vande Woude, George; Xu, H. Eric

    2010-11-01

    Hepatocyte growth factor (HGF) is an activating ligand of the Met receptor tyrosine kinase, whose activity is essential for normal tissue development and organ regeneration but abnormal activation of Met has been implicated in growth, invasion, and metastasis of many types of solid tumors. HGF has two natural splice variants, NK1 and NK2, which contain the N-terminal domain (N) and the first kringle (K1) or the first two kringle domains of HGF. NK1, which is a Met agonist, forms a head-to-tail dimer complex in crystal structures and mutations in the NK1 dimer interface convert NK1 to a Met antagonist. In contrast, NK2 is a Met antagonist, capable of inhibiting HGF's activity in cell proliferation without clear mechanism. Here we report the crystal structure of NK2, which forms a 'closed' monomeric conformation through interdomain interactions between the N- domain and the second kringle domain (K2). Mutations that were designed to open up the NK2 closed conformation by disrupting the N/K2 interface convert NK2 from a Met antagonist to an agonist. Remarkably, this mutated NK2 agonist can be converted back to an antagonist by a mutation that disrupts the NK1/NK1 dimer interface. These results reveal the molecular determinants that regulate the agonist/antagonist properties of HGF NK2 and provide critical insights into the dimerization mechanism that regulates the Met receptor activation by HGF.

  8. Genetic regulation of growth from birth to 18 years of age: the Swedish young male twins study.

    PubMed

    Silventoinen, Karri; Pietiläinen, Kirsi H; Tynelius, Per; Sørensen, Thorkild I A; Kaprio, Jaakko; Rasmussen, Finn

    2008-01-01

    Growth is a complex process, and only little is known on the genetic regulation of it. We analyzed the effect of genetic and environmental factors on growth in a longitudinal Swedish cohort of 231 monozygotic and 144 dizygotic twin pairs born 1973-1979 with length or height measured annually from birth to age 18. The data were analyzed by two different multivariate variance component models for twin data using the Mx statistical package. At birth and 1 year of age, a substantial part of the variation in length was because of common environment (50 and 57%, respectively) and the effect of genetic factors was minor. After 2 years of age, 91-97% of the variation of height could be explained by genetic differences whereas the rest was because of environmental variation not shared by twins. The genetic correlation between heights at ages 2 and 18 was 0.73 (95% confidence intervals 0.68-0.77) showing that 53% of the genes affecting height at these ages are the same or closely linked; with increasing age the correlation with genetic effects at age 18 become subsequently stronger. Especially in mid-childhood, growth was largely regulated by the same genetic factors. During puberty new genetic factors started to affect height, but also genetic variation affecting height at previous ages remained. These results suggest that genetic regulation of growth is rather uniform, which is encouraging for further efforts to identify genes affecting growth.

  9. The population age structure and reproductive biology of Gyrodactylus salaris Malmberg (Monogenea).

    PubMed

    Harris, P D; Jansen, P A; Bakke, T A

    1994-02-01

    Gyrodactylus salaris has recently become a major pathogen of Atlantic Salmon (Salmo salar) in Norway. The survivorship, population age structure and pattern of insemination of G. salaris were studied to determine the extent to which this species reproduces sexually. The age-specific mortality schedule of G. salaris could be described by an exponential model but day to day variations were large, with an increase in mortality after each birth. Modelling population growth using the best fit mortality schedule indicated that, at stable age structure, 35% of the population would consist of newborn and pre-1st birth flukes. Using testis, penis and embryo development, pre-1st birth and immediately post-1st birth flukes could be unambiguously identified, and established infections were found to contain 35% pre-1st birth flukes, as predicted. The proportion of pre-1st birth flukes in newly established infections was significantly smaller, probably because of differences in the rate of transmission between newborn and older flukes. Gyrodactylus salaris is relatively long-lived, and more than 40% of the population may survive to give birth for the third time. As gyrodactylids are protogynous, and the first daughter is probably produced asexually, this long-lived strategy ensures that a large part of the G. salaris population possesses a functional male system, and that the asexually derived flukes are a smaller component of the total population in this species. Flukes with whorls of inseminated spermatozoa within the seminal receptacle were found in all age groups possessing a functional male system, and were interpreted as having been cross-inseminated.(ABSTRACT TRUNCATED AT 250 WORDS)

  10. Fragmented Romanian Sociology: Growth and Structure of the Collaboration Network

    PubMed Central

    Hâncean, Marian-Gabriel; Perc, Matjaž; Vlăsceanu, Lazăr

    2014-01-01

    Structural patterns in collaboration networks are essential for understanding how new ideas, research practices, innovation or cooperation circulate and develop within academic communities and between and within university departments. In our research, we explore and investigate the structure of the collaboration network formed by the academics working full-time within all the 17 sociology departments across Romania. We show that the collaboration network is sparse and fragmented, and that it constitutes an environment that does not promote the circulation of new ideas and innovation within the field. Although recent years have witnessed an increase in the productivity of Romanian sociologists, there is still ample room for improvement in terms of the interaction infrastructure that ought to link individuals together so that they could maximize their potentials. We also fail to discern evidence in favor of the Matthew effect governing the growth of the network, which suggests scientific success and productivity are not rewarded. Instead, the structural properties of the collaboration network are partly those of a core-periphery network, where the spread of innovation and change can be explained by structural equivalence rather than by interpersonal influence models. We also provide support for the idea that, within the observed network, collaboration is the product of homophily rather than prestige effects. Further research on the subject based on data from other countries in the region is needed to place our results in a comparative framework, in particular to discern whether the behavior of the Romanian sociologist community is unique or rather common. PMID:25409180

  11. Fragmented Romanian sociology: growth and structure of the collaboration network.

    PubMed

    Hâncean, Marian-Gabriel; Perc, Matjaž; Vlăsceanu, Lazăr

    2014-01-01

    Structural patterns in collaboration networks are essential for understanding how new ideas, research practices, innovation or cooperation circulate and develop within academic communities and between and within university departments. In our research, we explore and investigate the structure of the collaboration network formed by the academics working full-time within all the 17 sociology departments across Romania. We show that the collaboration network is sparse and fragmented, and that it constitutes an environment that does not promote the circulation of new ideas and innovation within the field. Although recent years have witnessed an increase in the productivity of Romanian sociologists, there is still ample room for improvement in terms of the interaction infrastructure that ought to link individuals together so that they could maximize their potentials. We also fail to discern evidence in favor of the Matthew effect governing the growth of the network, which suggests scientific success and productivity are not rewarded. Instead, the structural properties of the collaboration network are partly those of a core-periphery network, where the spread of innovation and change can be explained by structural equivalence rather than by interpersonal influence models. We also provide support for the idea that, within the observed network, collaboration is the product of homophily rather than prestige effects. Further research on the subject based on data from other countries in the region is needed to place our results in a comparative framework, in particular to discern whether the behavior of the Romanian sociologist community is unique or rather common.

  12. Geo-structural mapping and age determinations of Rembrandt basin.

    NASA Astrophysics Data System (ADS)

    Ferrari, Sabrina; Massironi, Matteo; Martellato, Elena; Giacomini, Lorenza; Cremonese, Gabriele; Rothery, David; Prockter, Louise M.

    During its second and thirds flybys MESSENGER imaged a new large and well-preserved basin called Rembrandt Basin (Watters et al., 2009) in Mercury's southern hemisphere. Rembrandt is partially filled by volcanic overlay and is crossed by a marked lobate scarp with some similarities to another prominent mercurian lobate scarp, Beagle Rupes. In attempt to reveal Rembrandt Basin evolution, we mapped its geological units inferring -where possible -their stratigraphic relationships. In addition, we performed crater counts on several of these units and derived age estimates by applying Model Production Function (MPF) absolute-model chronology (Marchi et al., 2009). Since Rembrandt basin (in contrast to other well-seen basins) displays evidence of global-scale in addition to basin-localized deformation (Watters et al. 2009), it is characterized by different tectonic features that in some cases may be controlled by rheological layering within the crust. We attempted to map the contractional and extensional local patterns and the global tectonic features. Notably, the pronounced scarp transecting a 60 km crater near the edge of Rembrandt's inner ring and other structural features in the surrounding regions suggest a linked fault system. The apparent bow shape of this feature could be compared with Beagle Rupes, and similarly may imply special conditions of weakness inside the crust (Rothery and Massironi, 2010). Ref. Watters, T. R., Head, J. W., Solomon, S. C., Robinson, M. S., Chapman, C. R., Denevi, B. W., Fassett, C. I., Murchie, S. L., and Strom, R. G., 2009. Evolution of the Rembrandt Impact Basin on Mercury. Science, 324 , 618-621. Marchi, S., Mottola, S., Cremonese, G., Massironi, M., and Martellato, E., 2009. A new Chronology for the Moon and Mercury. Astronomical Journal, 137 , 4936-4948. Rothery, D. A. and Massironi, M., 2010. Beagle Rupes -evidence for a basal decollement of regional extent in Mercury's lithosphere. Icarus (In Press).

  13. Growth activity in human septal cartilage: age-dependent incorporation of labeled sulfate in different anatomic locations

    SciTech Connect

    Vetter, U.; Pirsig, W.; Heinze, E.

    1983-02-01

    Growth activity in different areas of human septal cartilage was measured by the in vitro incorporation of /sup 35/S-labeled NaSO/sub 4/ into chondroitin sulfate. Septal cartilage without perichondrium was obtained during rhinoplasty from 36 patients aged 6 to 35 years. It could be shown that the anterior free end of the septum displays high growth activity in all age groups. The supra-premaxillary area displayed its highest growth activity during prepuberty, showing thereafter a continuous decline during puberty and adulthood. A similar age-dependent pattern in growth activity was found in the caudal prolongation of the septal cartilage. No age-dependent variations could be detected in the posterior area of the septal cartilage.

  14. Growth, size and age at maturity of the agile frog (Rana dalmatina) in an Iberian Peninsula population.

    PubMed

    Sarasola-Puente, Vanessa; Gosá, Alberto; Oromí, Neus; Madeira, María José; Lizana, Miguel

    2011-06-01

    The mean age of a population of agile frogs (Rana dalmatina) from the Iberian Peninsula was estimated using mark and recapture and skeletochronology. Life-history parameters, including growth rate, body length, age and size at maturity, sexual dimorphism and longevity, were studied. The regression between age and snout-vent length (SVL) was highly significant in both sexes. Males reached sexual maturity at two years of age, although sometimes they can reach it at only one year of age. The average SVL at maturity was 51.75 mm (standard error (SE)=0.71; n=45). Females reached sexual maturity at two years of age with an average SVL of 62.14 mm (SE=2.20; n=14). A subset of the female population reached sexual maturity at three years of age. Growth was rapid until sexual maturity was reached. There was an overlap of SVL between different age classes. Growth was continuous, fulfilling the conditions of Von Bertalanffy's model. The growth coefficient (K) was 0.840 in males and 0.625 in females. The maximum SVL was greater in females (73.00 mm) than in males (59.50mm). Sexual dimorphism was significantly biased towards females in all age classes. The maximum longevity observed was 6 years in females and 8 years in males. Management strategies for agile frogs should take into account factors such as these life-history characteristics.

  15. Early diagnosis and treatment referral of children born small for gestational age without catch-up growth are critical for optimal growth outcomes

    PubMed Central

    2012-01-01

    Approximately 10% of children born small for their gestational age (SGA) fail to show catch-up growth and may remain short-statured as adults. Despite treatment guidelines for children born SGA that recommend referral for growth hormone (GH) therapy evaluation and initiation by ages 2 to 4 years, the average age of GH treatment initiation is typically much later, at ages 7 to 9 years. Delayed referral for GH treatment is problematic as studies show younger age at GH treatment initiation in children born SGA is an independent predictor for responses such as optimal growth acceleration, normalization of prepubertal height, and most importantly, adult height (AH). This review discusses the importance and associated challenges of early diagnosis of children born SGA who fail to show catch-up growth, contrasts the recommended age of referral for these patients and the average age of GH treatment initiation, and discusses studies showing the significant positive effects of early referral and treatment with GH on AHs in short-statured children born SGA. To optimize the eventual height in short-statured SGA children who fail to manifest catch-up growth, a lowering of the average age of referral for GH therapy evaluation is needed to better align with consensus recommendations for SGA management. The importance of increasing parental and physician awareness that most children born SGA will do well developmentally and will optimally benefit from early initiation of GH treatment when short-statured is addressed, as is the need to shift the age of referral to better align with consensus recommendations. PMID:22559301

  16. Age, growth, maturity, and fecundity of 'humper' lake trout, Isle Royale, Lake Superior

    USGS Publications Warehouse

    Rahrer, Jerold F.

    1965-01-01

    Humper lake trout are one of the several races or subpopulations of lake trout in Lake Superior. This study is based on 3,705 fish collected on a reef south of Isle Royale near the eastern end. The mean lengths of humper trout from commercial gill nets were smaller than those of lean lake trout. Members of age-groups VII, VIII, and IX represented 81.5 per cent of the commercial humper catch. The body-scale relation was described by two intersecting straight lines. The weight of humper trout increased as the 3.282 power of the length. Growth in length was slow and ranged from 1.6 to 3.5 inches per year. Annual increments were greatest in the first, sixth, and seventh years. Growth in weight was also slow but increased each year. Humper trout became legal (1 1/2 pounds) in the eighth year of life and reached 5 pounds in 11 years. All fish longer than 19.1 inches and older than age-group VIII were mature; the shortest mature fish were: males, 12.7 inches; females, 14.7 inches. At minimum legal size, 98 per cent of the males and 56 per cent of the females were mature. Humper trout produced an average of 1,351 eggs per fish or 516 per pound.

  17. Nucleotide supplementation and the growth of term small for gestational age infants.

    PubMed

    Cosgrove, M; Davies, D P; Jenkins, H R

    1996-03-01

    A double blind randomised controlled trial in small for gestational age (SGA) infants, whose intestinal mucosa was shown to be functionally impaired as a result of intrauterine undernutrition, was carried out to investigate the hypothesis that nucleotide supplementation of a milk formula could improve catchup growth. Anthropometric data were collected on 74 infants, 39 randomly allocated to the nucleotide supplemented group (group N) and 35 to a standard formula group (group S). From study entry to 2 months of age, infants in group N had significantly higher mean rates of weight gain (106.3 compared with 94.7 g/kg baseline weight/week) and length gain (21.8 v 19.7 mm/m baseline length/week). Over the whole six months for which the trial formula was provided group N had significantly higher mean rates of gain of weight (80.1 compared with 71.8 g/kg baseline weight/week), length (16.2 compared with 15.0 mm/m baseline length/week), and head circumference (11.8 compared with 10.8 mm/m baseline head circumference/week). Catchup growth in SGA infants is therefore improved by nucleotide supplementation of infant formula.

  18. Age and growth and maturity of southern Africa's largest cyprinid fish, the largemouth yellowfish Labeobarbus kimberleyensis.

    PubMed

    Ellender, B R; Weyl, O L F; Winker, H

    2012-09-01

    The aim of this study was to use specimens of the largemouth yellowfish Labeobarbus kimberleyensis, southern Africa's largest cyprinid [IUCN red-listed as Near Threatened (NT)], obtained from gillnet by-catch to describe aspects of its biology in order to assist future conservation and management decisions. Ninety three L. kimberleyensis were collected between March 2007 and May 2008 from Lake Gariep, South Africa. Labeobarbus kimberleyensis was present in 38% of all gillnet catches, but in low numbers (2% of the catch) and it contributed 8% to the catch by mass. Age was estimated using astericus otoliths. Growth increment formation on these otoliths was validated as annual using edge analysis and the mark-recapture of chemically tagged captive fish. Resultant analysis showed that the species is slow growing and the oldest aged fish was a 17 year, 690 mm fork length (L(F)) male. The smallest ripe female fish measured 394 mm L(F) and was 7+ years old and the smallest mature male was 337 mm L(F) and 5+ years old. Slow growth and late maturity make this species vulnerable to exploitation emphasizing the need for continued high conservation priority.

  19. Vertebral microanatomy in squamates: structure, growth and ecological correlates

    PubMed Central

    Houssaye, Alexandra; Mazurier, Arnaud; Herrel, Anthony; Volpato, Virginie; Tafforeau, Paul; Boistel, Renaud; de Buffrénil, Vivian

    2010-01-01

    The histological study of vertebrae in extant squamates shows that the internal vertebral structure in this group differs from that of other tetrapods. Squamate vertebrae are lightly built and basically composed of two roughly concentric osseous tubes – one surrounding the neural canal and the other constituting the peripheral cortex of the vertebra – connected by few thin trabeculae. This structure, which characteristically evokes that of a tubular bone, results from a peculiar remodelling process characterised by an imbalance between local bone resorption and redeposition; in both periosteal and endosteo-endochondral territories, bone is extensively resorbed but not reconstructed in the same proportion by secondary deposits. This process is particularly intense in the deep region of the centrum, where originally compact cortices are made cancellous, and where the endochondral spongiosa is very loose. This remodelling process starts at an early stage of development and remains active throughout subsequent growth. The growth of squamate centra is also strongly asymmetrical, with the posterior (condylar) part growing much faster than the anterior (cotylar) part. Preliminary analyses testing for associations between vertebral structure and habitat use suggest that vertebrae of fossorial taxa are denser than those of terrestrial taxa, those in aquatic taxa being of intermediate density. However, phylogenetically informed analyses do not corroborate these findings, thus suggesting a strong phylogenetic signal in the data. As our analyses demonstrate that vertebrae in snakes are generally denser than those of lizards sensu stricto, this may drive the presence of a phylogenetic signal in the data. More comprehensive sampling of fossorial and aquatic lizards is clearly needed to more rigorously evaluate these patterns. PMID:21039477

  20. Reoccupation of floodplains by rivers and its relation to the age structure of floodplain vegetation

    USGS Publications Warehouse

    Konrad, Christopher P.

    2012-01-01

    River channel dynamics over many decades provide a physical control on the age structure of floodplain vegetation as a river occupies and abandons locations. Floodplain reoccupation by a river, in particular, determines the interval of time during which vegetation can establish and mature. A general framework for analyzing floodplain reoccupation and a time series model are developed and applied to five alluvial rivers in the United States. Channel dynamics in these rivers demonstrate time-scale dependence with short-term oscillation in active channel area in response to floods and subsequent vegetation growth and progressive lateral movement that accounts for much of the cumulative area occupied by the rivers over decades. Rivers preferentially reoccupy locations recently abandoned causing a decreasing probability of reoccupation with time since abandonment. For a typical case, a river is 10 times more likely to reoccupy an area it abandoned in the past decade than it is to reoccupy an area it abandoned 30 yrs ago. The decreasing probability of reoccupation over time is consistent with observations of persistent stands of late seral stage floodplain forest. A power function provides a robust approach for estimating the cumulative area occupied by a river and the age structure of riparian forests resulting from a specific historical sequence of streamflow in comparison to either linear or exponential alternatives.

  1. 77 FR 27815 - Aging Management of Stainless Steel Structures and Components in Treated Borated Water

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-11

    ... COMMISSION Aging Management of Stainless Steel Structures and Components in Treated Borated Water AGENCY..., ``Aging Management of Stainless Steel Structures and Components in Treated Borated Water.'' This LR-ISG... stainless steel structures and components exposed to treated borated water. The NRC published Revision 2...

  2. Age and Growth of the Round Stingray Urotrygon rogersi, a Particularly Fast-Growing and Short-Lived Elasmobranch

    PubMed Central

    Mejía-Falla, Paola A.; Cortés, Enric; Navia, Andrés F.; Zapata, Fernando A.

    2014-01-01

    We examined the age and growth of Urotrygon rogersi on the Colombian coast of the Eastern Tropical Pacific Ocean by directly estimating age using vertebral centra. We verified annual deposition of growth increments with marginal increment analysis. Eight growth curves were fitted to four data sets defined on the basis of the reproductive cycle (unadjusted or adjusted for age at first band) and size variables (disc width or total length). Model performance was evaluated using Akaike's Information Criterion (AIC), AIC weights and multi-model inference criteria. A two-phase growth function with adjusted age provided the best description of growth for females (based on five parameters, DW∞  =  20.1 cm, k  =  0.22 yr–1) and males (based on four and five parameters, DW∞  =  15.5 cm, k  =  0.65 yr–1). Median maturity of female and male U. rogersi is reached very fast (mean ± SE  =  1.0 ± 0.1 year). This is the first age and growth study for a species of the genus Urotrygon and results indicate that U. rogersi attains a smaller maximum size and has a shorter lifespan and lower median age at maturity than species of closely related genera. These life history traits are in contrast with those typically reported for other elasmobranchs. PMID:24776963

  3. Age and growth of the round stingray Urotrygon rogersi, a particularly fast-growing and short-lived elasmobranch.

    PubMed

    Mejía-Falla, Paola A; Cortés, Enric; Navia, Andrés F; Zapata, Fernando A

    2014-01-01

    We examined the age and growth of Urotrygon rogersi on the Colombian coast of the Eastern Tropical Pacific Ocean by directly estimating age using vertebral centra. We verified annual deposition of growth increments with marginal increment analysis. Eight growth curves were fitted to four data sets defined on the basis of the reproductive cycle (unadjusted or adjusted for age at first band) and size variables (disc width or total length). Model performance was evaluated using Akaike's Information Criterion (AIC), AIC weights and multi-model inference criteria. A two-phase growth function with adjusted age provided the best description of growth for females (based on five parameters, DW∞  =  20.1 cm, k  =  0.22 yr⁻¹) and males (based on four and five parameters, DW(∞)  =  15.5 cm, k  =  0.65 yr⁻¹). Median maturity of female and male U. rogersi is reached very fast (mean ± SE  =  1.0 ± 0.1 year). This is the first age and growth study for a species of the genus Urotrygon and results indicate that U. rogersi attains a smaller maximum size and has a shorter lifespan and lower median age at maturity than species of closely related genera. These life history traits are in contrast with those typically reported for other elasmobranchs.

  4. Nutritional status and growth parameters of school-age Roma children in the Republic of Macedonia.

    PubMed

    Spiroski, Igor; Dimitrovska, Zlatanka; Gjorgjev, Dragan; Mikik, Vladimir; Efremova-Stefanoska, Vesna; Naunova-Spiroska, Daniela; Kendrovski, Vladimir

    2011-06-01

    Main objective of the study was to assess the nutritional status of school age Roma children in Macedonia in order to detect precursors of possible health risks at an early age. The study was designed as a comparative case control study. Study group consisted of 229 Roma school children from the 1st and 272 from the 5th grade residing in different towns in Macedonia. The control group was recruited from other than Roma ethnic background and consisted of 283 children attending 1st and 356 children attending 5th grade. Every participant was measured for his/hers body height and weight. The t-test and Chi square (Chi2) were applied to test statistical significance of variables. The WHO's AnthroPlus software was applied to assess growth parameters and population at risk. There were significant differences in values of the body weight (p = 0.001) and height (p = 0.001) between Roma and non-Roma children attending the 1st grade of primary school. Weight-for-age, height-for-age and BMI-for-age indexes of the 1st grade children significantly differred in in the same intervals of SD (> or = -2SD and < -1SD; > or = -1SD and median; > +1SD and < or = +2SD; between Roma and non-Roma 5th graders. Anthropometric parameters of nutritional status of Roma children in Macedonia are significantly different than those of their non-Roma peers. Their health risks are predominantly related to underweight. The parameters related to health risks of overweight or obesity are lower in Roma than in non-Roma children.

  5. Age, growth, and maturity of the longnose sucker Catostomus catostomus, of western Lake Superior

    USGS Publications Warehouse

    Bailey, Merryll M.

    1969-01-01

    Studies of age, growth, and maturity were based on 1760 fish collected in western Lake Superior in 1964-65. The body:scale relation was curvilinear and the curve had an intercept of 1.65 inches on the length axis. The weight increased as the 2.85 power of the length. Some fish formed an annulus before May 18 in 1965; all had completed annuli by late September. Longnose suckers grew 3.6 inches the 1st year, reached 12 inches in the 6th year, and 18 inches in the 11th year. Fish from Pikes Bay grew faster than those from Gull Island Shoal. Over 6 years were required for weight to reach 1 lb and nearly 10 years to reach 2 lb. Minimum length at maturity was 10.5 inches for males and 11.5 inches for females. The youngest mature male belonged to age-group IV and the youngest mature female to age-group V. All males were mature at 14.5-14.9 inches (age-group VIII) and all females at 15.0-15.4 inches (age-group IX). Finclipped longnose suckers returned to spawn in the Brule River in successive years. One fish returned to spawn in 4 successive years. Many of the fish were not recaptured until 2 or 3 years after marking. The time of the Brule River spawning migration depended more on water temperature than on length of day. The average water temperature during the peak of the spawning runs of 1958-64 was 55.4 F. Larval suckers apparently spend little time in the Brule River and adjacent streams and drift downstream to the lake soon after hatching. The number of eggs in the ovaries of eight suckers ranged from 14 to 35 thousand and averaged 24 thousand for fish 13.9-17.7 inches long.

  6. Genetic and environmental determinants of growth of school-aged children in a rural Colombian population.

    PubMed

    Mueller, W H; Titcomb, M

    1977-01-01

    Parent-offspring correlations and heritabilities of body measurements from midparent-offspring regressions are presented for school-aged children from the village of Tenza, Colombia (N = 403 families). Parent-child correlations and midparent regressions in this subsistence farming sample, are similar in magnitude to those for well nourished, urban industrial samples, suggesting that the environmental component of variability in body size is the same regardless of the environment. Tenza children are significantly shorter and lighter than upper class Bogota children, and Tenza parents have mean heights and weights similar to those of other lower class Colombian samples. Thus, chronic undernutrition has affected the growth of parents and continues to affect the growth of the present generation. Although it has been hypothesized that heritability of growth might be reduced in samples experiencing malnutrition and its sequelae, such a reduction may only be observable where environment of parents during their development is different from that of their offspring, which is not the case here. The pattern of heritabilities with respect to different body measurements in Tenza, is similar to that seen in well nourished samples, except that measurements of breadth (biacromial, bicristal, bicondylar) have heritabilities similar in magnitude to those of linear measurements (height, sitting-height, subischial length) especially in males; and heritabilities of some measurements related to adiposity are significantly higher in daughters than in sons.

  7. Age, growth, and production of the yellow perch, Perca flavescens (Mitchill), of Saginaw Bay

    USGS Publications Warehouse

    Hile, Ralph; Jobes, Frank W.

    1941-01-01

    Ages were determined and individual growth histories computed from the examination and measurement of scales from 820 yellow perch collected in 1929 and 1930. Calculated lengths greater than 101 millimeters were computed on the assumption (supported by empirical data) that the ratio of body length to scale length is constant. Lengths below 101 millimeters were determined with the aid of an empirical curve of the body-scale relationship of small fish. Yellow perch of age-groups III and IV (in the fourth and fifth years of life) made up the bulk of the collection (78 per cent). Females grew slightly more rapidly than males, but members of both sexes attained the legal length of 8 1/2 inches during the fourth year of life, just as they were entering on the period of most rapid growth in weight. The greatest growth in weight of both sexes occurred in the sixth year of life. In the combined samples of the two years the females exceeded the males in abundance in the ratio, 296:100. The weight of the Saginaw Bay yellow perch was found to increase as the 3.117 power of the length. The relative length of the tail decreased with increase in the length of the fish. The Saginaw Bay yellow perch is now far less abundant than it was in the early years of the fishery. The average annual production of 548,000 pounds over the period, 1917-1938, was only 28 per cent of the earlier (1891-1916) "normal" annual production of 1,961,000 pounds. A detailed analysis of statistical data available for more recent years made possible a description of annual fluctuations in the abundance and production of yellow perch and in the intensity of the yellow perch fishery in Saginaw Bay over the period, 1929-1938.

  8. FASTRAN II - FATIGUE CRACK GROWTH STRUCTURAL ANALYSIS (UNIX VERSION)

    NASA Technical Reports Server (NTRS)

    Newman, J. C.

    1994-01-01

    Predictions of fatigue crack growth behavior can be made with the Fatigue Crack Growth Structural Analysis (FASTRAN II) computer program. As cyclic loads are applied to a selected crack configuration with an initial crack size, FASTRAN II predicts crack growth as a function of cyclic load history until either a desired crack size is reached or failure occurs. FASTRAN II is based on plasticity-induced crack-closure behavior of cracks in metallic materials and accounts for load-interaction effects, such as retardation and acceleration, under variable-amplitude loading. The closure model is based on the Dugdale model with modifications to allow plastically deformed material to be left along the crack surfaces as the crack grows. Plane stress and plane strain conditions, as well as conditions between these two, can be simulated in FASTRAN II by using a constraint factor on tensile yielding at the crack front to approximately account for three-dimensional stress states. FASTRAN II contains seventeen predefined crack configurations (standard laboratory fatigue crack growth rate specimens and many common crack configurations found in structures); and the user can define one additional crack configuration. The baseline crack growth rate properties (effective stress-intensity factor against crack growth rate) may be given in either equation or tabular form. For three-dimensional crack configurations, such as surface cracks or corner cracks at holes or notches, the fatigue crack growth rate properties may be different in the crack depth and crack length directions. Final failure of the cracked structure can be modelled with fracture toughness properties using either linear-elastic fracture mechanics (brittle materials), a two-parameter fracture criterion (brittle to ductile materials), or plastic collapse (extremely ductile materials). The crack configurations in FASTRAN II can be subjected to either constant-amplitude, variable-amplitude or spectrum loading. The applied

  9. FASTRAN II - FATIGUE CRACK GROWTH STRUCTURAL ANALYSIS (IBM PC VERSION)

    NASA Technical Reports Server (NTRS)

    Newman, J. C.

    1994-01-01

    Predictions of fatigue crack growth behavior can be made with the Fatigue Crack Growth Structural Analysis (FASTRAN II) computer program. As cyclic loads are applied to a selected crack configuration with an initial crack size, FASTRAN II predicts crack growth as a function of cyclic load history until either a desired crack size is reached or failure occurs. FASTRAN II is based on plasticity-induced crack-closure behavior of cracks in metallic materials and accounts for load-interaction effects, such as retardation and acceleration, under variable-amplitude loading. The closure model is based on the Dugdale model with modifications to allow plastically deformed material to be left along the crack surfaces as the crack grows. Plane stress and plane strain conditions, as well as conditions between these two, can be simulated in FASTRAN II by using a constraint factor on tensile yielding at the crack front to approximately account for three-dimensional stress states. FASTRAN II contains seventeen predefined crack configurations (standard laboratory fatigue crack growth rate specimens and many common crack configurations found in structures); and the user can define one additional crack configuration. The baseline crack growth rate properties (effective stress-intensity factor against crack growth rate) may be given in either equation or tabular form. For three-dimensional crack configurations, such as surface cracks or corner cracks at holes or notches, the fatigue crack growth rate properties may be different in the crack depth and crack length directions. Final failure of the cracked structure can be modelled with fracture toughness properties using either linear-elastic fracture mechanics (brittle materials), a two-parameter fracture criterion (brittle to ductile materials), or plastic collapse (extremely ductile materials). The crack configurations in FASTRAN II can be subjected to either constant-amplitude, variable-amplitude or spectrum loading. The applied

  10. Catch-Up Growth Assessment in Long-Term Physically Neglected and Emotionally Abused Preschool Age Male Children.

    ERIC Educational Resources Information Center

    Olivan, Gonzalo

    2003-01-01

    A longitudinal study examined 20 neglected and emotionally abused boys (ages 30-42 months) who entered foster residential care and remained a year after initial placement. At placement, children showed a mild form of chronic malnutrition with growth failure. Growth failure was reversible after the first year of stay. (Contains references.)…

  11. Effects of Aging Structures and Humidity on Fatigue Properties of Maraging Steel

    NASA Astrophysics Data System (ADS)

    Hayashi, Kousuke; Nagano, Takanori; Moriyama, Michihiko; Wang, Xishu; Kawagoishi, Norio

    Effects of aging structures and humidity on fatigue properties of 350 grade 18% Ni maraging steel were investigated under rotating bending in relative humidity of 25% and 85%. Aging conditions tested were a conventional single aging and a double one which was aged at low temperature after the conventional aging. In each aging, under and peak aged steels were prepared. Tensile strength was increased by the double aging without reduction of the ductility. Proportional relation between fatigue limit and Vickers hardness held until 750HV in low humidity. However fatigue strength was largely decreased by high humidity, especially in the peak aged steel at the single aging. The decrease in fatigue strength by high humidity was mainly caused by the acceleration of a crack initiation due to the anodic dissolution. The acceleration of a crack initiation was larger in the steel peak aged at the single aging with larger precipitated particles.

  12. Age, growth, and recruitment patterns of juvenile ladyfish (Elops sp) from the east coast of Florida (USA)

    PubMed Central

    2015-01-01

    Ladyfish (Elops sp) are a common and economically valuable coastal nearshore species found along coastal beaches, bays, and estuaries of the southeastern United States, and subtropical and tropical regions worldwide. Previously, ladyfish were a substantial bycatch in Florida’s commercial fisheries, but changes in regulations significantly reduced commercial landings. Today, ladyfish are still taken in commercial fisheries in Florida, but many are also taken by recreational anglers. Life-history information and research interest in ladyfish is almost non-existent, especially information on age and growth. Thus, the overarching purpose of this study was to expand our understanding of ladyfish age and growth characteristics. The specific objectives were to describe, for the first time, age, growth, and recruitment patterns of juvenile ladyfish from the east coast of Florida (USA). In the Indian River Lagoon (IRL), annual monthly length-frequency distributions were confounded because a few small individuals recruited throughout the year; monthly length-frequency data generally demonstrated a cyclical pattern. The smallest were collected in September and the largest in May. Post-hoc analysis showed no significant difference in length between August and May, or among the other months. In Volusia County (VC), annual monthly length-frequency distribution demonstrated growth generally occurred from late-winter and spring to summer. The smallest ladyfish were collected in February and the largest in August. On average, the absolute growth rate in the IRL was 36.3 mm in 60 days or 0.605 mm day−1. Cohort-specific daily growth rates, elevations, and coincidentals were similar among sampling years. Cohort-specific growth rates ranged from 1.807 in 1993 to 1.811 mm day−1 in 1994. Overall, growth was best (i.e., goodness of fit) described by exponential regression. On average, the absolute growth rate in VC was 28 mm in 150 days or 0.1866 mm day−1. Cohort-specific daily

  13. Growth Mechanism of a Unique Hierarchical Vaterite Structure

    NASA Astrophysics Data System (ADS)

    Ma, Guobin; Xu, Yifei; Wang, Mu

    2013-03-01

    Calcium carbonate is one of the most significant minerals in nature as well as in biogenic sources. Calcium carbonate occurs naturally in three crystalline polymorphs, i.e., calcite, aragonite, and vaterite. Although it has been attracted much research attention to understanding of the formation mechanisms of the material, the properties of the vaterite polymorph is not well known. Here we report synthesis and formation mechanism of a unique hierarchical structure of vaterite. The material is grown by a controlled diffusion method. The structure possesses a core and an outer part. The core is convex lens-like and is formed by vaterite nanocrystals that have small misorientations. The outer part is separated into six garlic clove-like segments. Each segment possesses piles of plate-like vaterite crystals, and the orientations of the plates continuously change from pile to pile. Based on real-time experimental results and the structural analysis, a growth mechanism is presented. Work supported by NSFC (Grant No. 51172104) and MOST of China (Grant No. 2101CB630705)

  14. Structure and Correlates of Cognitive Aging in a Narrow Age Cohort

    PubMed Central

    2014-01-01

    Aging-related changes occur for multiple domains of cognitive functioning. An accumulating body of research indicates that, rather than representing statistically independent phenomena, aging-related cognitive changes are moderately to strongly correlated across domains. However, previous studies have typically been conducted in age-heterogeneous samples over longitudinal time lags of 6 or more years, and have failed to consider whether results are robust to a comprehensive set of controls. Capitalizing on 3-year longitudinal data from the Lothian Birth Cohort of 1936, we took a longitudinal narrow age cohort approach to examine cross-domain cognitive change interrelations from ages 70 to 73 years. We fit multivariate latent difference score models to factors representing visuospatial ability, processing speed, memory, and crystallized ability. Changes were moderately interrelated, with a general factor of change accounting for 47% of the variance in changes across domains. Change interrelations persisted at close to full strength after controlling for a comprehensive set of demographic, physical, and medical factors including educational attainment, childhood intelligence, physical function, APOE genotype, smoking status, diagnosis of hypertension, diagnosis of cardiovascular disease, and diagnosis of diabetes. Thus, the positive manifold of aging-related cognitive changes is highly robust in that it can be detected in a narrow age cohort followed over a relatively brief longitudinal period, and persists even after controlling for many potential confounders. PMID:24955992

  15. The age, growth, and feeding habits of the whitefish Coregonus clupeaformis (Mitchell), of Lake Champlain

    USGS Publications Warehouse

    Van Oosten, John; Deason, Hilary J.

    1939-01-01

    This study is based on 120 whitefish collected in northern Lake Champlain (Missisquoi Bay) in 1930 and on 175 whitefish taken in southern Lake Champlain in 1931. Since the whitefish population had not been exploited commercially after 1912 in United States waters and after 1915 in Canadian waters, its study should be of interest in showing the characteristics of a population practically untouched by man. Data have been presented on length frequencies, age composition, growth, coefficient of condition, sex ratio, standard length-total length relationship, and feeding habits. The data indicated that the Missisquoi Bay population was disturbed (probably by the early fall seining of 1930) before our samples were taken so that the original length distributions no longer existed. The southern Lake Champlain material, however, showed a consistency which indicated that the population had not been exploited to any extensive degree, if at all. When the northern population was compared with the southern the former was found to differ from the latter in the following respects, which differences pointed to some disturbance of the northern stock in the lake 1. By possession of lower modes and smaller grand averages of length. 2. By absence of very old individuals. 3. By absence of a series of equally abundant age groups or, in other words, by the presence of a decided dominance of one or two age groups. 4. By a radical disagreement between the sexes in their age-frequency distribution. 5. By a disagreement between the sexes with respect to maximum lengths attained. All of the differences between the two collections could, however, not be attributed to exploitation. The following characteristics indicated the presence of two distinct populations in the lake 1. Presence of a spawning ground at each end of the lake. 2. Differences in calculated lengths and increments of length (growth rates). 3. Differences in the actual lengths and weights of corresponding age groups at capture. 4

  16. Structure and development of old-growth, unmanaged second-growth, and extended rotation Pinus resinosa forests in Minnesota, USA

    USGS Publications Warehouse

    Silver, Emily J.; D'Amato, Anthony W.; Fraver, Shawn; Palik, Brian J.; Bradford, John B.

    2013-01-01

    The structure and developmental dynamics of old-growth forests often serve as important baselines for restoration prescriptions aimed at promoting more complex structural conditions in managed forest landscapes. Nonetheless, long-term information on natural patterns of development is rare for many commercially important and ecologically widespread forest types. Moreover, the effectiveness of approaches recommended for restoring old-growth structural conditions to managed forests, such as the application of extended rotation forestry, has been little studied. This study uses several long-term datasets from old growth, extended rotation, and unmanaged second growth Pinus resinosa (red pine) forests in northern Minnesota, USA, to quantify the range of variation in structural conditions for this forest type and to evaluate the effectiveness of extended rotation forestry at promoting the development of late-successional structural conditions. Long-term tree population data from permanent plots for one of the old-growth stands and the extended rotation stands (87 and 61 years, respectively) also allowed for an examination of the long-term structural dynamics of these systems. Old-growth forests were more structurally complex than unmanaged second-growth and extended rotation red pine stands, due in large part to the significantly higher volumes of coarse woody debris (70.7 vs. 11.5 and 4.7 m3/ha, respectively) and higher snag basal area (6.9 vs. 2.9 and 0.5 m2/ha, respectively). In addition, old-growth forests, although red pine-dominated, contained a greater abundance of other species, including Pinus strobus, Abies balsamea, and Picea glauca relative to the other stand types examined. These differences between stand types largely reflect historic gap-scale disturbances within the old-growth systems and their corresponding structural and compositional legacies. Nonetheless, extended rotation thinning treatments, by accelerating advancement to larger tree diameter

  17. Interaction between insulin-like growth factor-1 and atherosclerosis and vascular aging.

    PubMed

    Higashi, Yusuke; Quevedo, Henry C; Tiwari, Summit; Sukhanov, Sergiy; Shai, Shaw-Yung; Anwar, Asif; Delafontaine, Patrice

    2014-01-01

    The process of vascular aging encompasses alterations in the function of endothelial (ECs) and vascular smooth muscle cells (VSMCs) via oxidation, inflammation, cell senescence and epigenetic modifications, increasing the probability of atherosclerosis. Aged vessels exhibit decreased endothelial antithrombogenic properties, increased reactive oxygen species generation, inflammatory signaling and migration of VSMCs to the subintimal space, impaired angiogenesis and increased elastin degradation. The key initiating step in atherogenesis is subendothelial accumulation of apolipoprotein B-containing low-density lipoproteins resulting in activation of ECs and recruitment of monocytes. Activated ECs secrete 'chemokines' that interact with cognate chemokine receptors on monocytes and promote directional migration. Recruitment of immune cells establishes a proinflammatory status, further causing elevated oxidative stress, which in turn triggers a series of events including apoptotic or necrotic death of vascular and nonvascular cells. Increased oxidative stress is also considered to be a key factor in mechanisms of aging-associated changes in tissue integrity and function. Experimental evidence indicates that insulin-like growth factor-1 exerts antioxidant, anti-inflammatory and pro-survival effects on the vasculature, reducing atherosclerotic plaque burden and promoting features of atherosclerotic plaque stability.

  18. Nerve growth factor in the adult brain of a teleostean model for aging research: Nothobranchius furzeri.

    PubMed

    D'Angelo, L; Castaldo, L; Cellerino, A; de Girolamo, P; Lucini, C

    2014-07-01

    Nerve growth factor (NGF) acts on central nervous system neurons, regulating naturally occurring cell death, synaptic connectivity, fiber guidance and dendritic morphology. The dynamically regulated production of NGF beginning in development, extends throughout adult life and aging, exerting numerous roles through a surprising variety of neurons and glial cells. This study analyzes the localization of NGF in the brain of the teleost fish Nothobranchius furzeri, an emerging model for aging research due to its short lifespan. Immunochemical and immunohistochemical experiments were performed by employing an antibody mapping at the N-terminus of the mature chain human origin NGF. Western blot analysis revealed an intense and well defined band of 20 kDa, which corresponds to proNGF of N. furzeri. Immunohistochemistry revealed NGF immunoreactivity (IR) diffused throughout all regions of telencephalon, diencephalon, mesencephalon and rhomboencephalon. It was detected in neurons and in glial cells, the latter mostly lining the mesencephalic and rhomboencephalic ventricles. Particularly in neurons, NGF IR was localized in perikarya and, to a less extent, in fibers. The widespread distribution of proNGF suggests that it might modulate numerous physiological functions in the adult brain of N. furzeri. The present survey constitutes a baseline study to enhance the understanding of the mechanisms underlying the role of NGF during aging processes.

  19. Insulin-like growth factor-1 in CNS and cerebrovascular aging

    PubMed Central

    Sonntag, William E.; Deak, Ferenc; Ashpole, Nicole; Toth, Peter; Csiszar, Anna; Freeman, Willard; Ungvari, Zoltan

    2013-01-01

    Insulin-like growth factor-1 (IGF-1) is an important anabolic hormone that decreases with age. In the past two decades, extensive research has determined that the reduction in IGF-1 is an important component of the age-related decline in cognitive function in multiple species including humans. Deficiency in circulating IGF-1 results in impairment in processing speed and deficiencies in both spatial and working memory. Replacement of IGF-1 or factors that increase IGF-1 to old animals and humans reverses many of these cognitive deficits. Despite the overwhelming evidence for IGF-1 as an important neurotrophic agent, the specific mechanisms through which IGF-1 acts have remained elusive. Recent evidence indicates that IGF-1 is both produced by and has important actions on the cerebrovasculature as well as neurons and glia. Nevertheless, the specific regulation and actions of brain- and vascular-derived IGF-1 is poorly understood. The diverse effects of IGF-1 discovered thus far reveal a complex endocrine and paracrine system essential for integrating many of the functions necessary for brain health. Identification of the mechanisms of IGF-1 actions will undoubtedly provide critical insight into regulation of brain function in general and the causes of cognitive decline with age. PMID:23847531

  20. National Survey To Validate General Growth Outcomes for Children between Birth and Age Eight: Initial Results. Technical Report #3.

    ERIC Educational Resources Information Center

    McConnell, Scott; McEvoy, Mary; Carta, Judith J.; Greenwood, Charles R.; Kaminski, Ruth; Good, Roland H., III; Shinn, Mark

    This monograph reports on a national mail survey to validate a set of general growth outcomes for children, including those with disabilities, between birth and age 8. The survey was part of a 5-year project to create a comprehensive measurement system to track the developmental progress of individual children with disabilities in this age range…

  1. Associations between genetic polymorphisms of insulin-like growth factor axis genes and risk for age-related macular degeneration

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Purpose: Our objective was to investigate if insulin-like growth factor (IGF) axis genes affect the risk for age-related macular degeneration (AMD). Methods: 864 Caucasian non-diabetic participants from the Age-Related Eye Disease Study (AREDS) Genetic Repository were used in this case control st...

  2. Cost-effective age structure and geographical distribution of boreal forest reserves.

    PubMed

    Lundström, Johanna; Ohman, Karin; Perhans, Karin; Rönnqvist, Mikael; Gustafsson, Lena; Bugman, Harald

    2011-02-01

    1. Forest reserves are established to preserve biodiversity, and to maintain natural functions and processes. Today there is heightened focus on old-growth stages, with less attention given to early successional stages. The biodiversity potential of younger forests has been overlooked, and the cost-effectiveness of incorporating different age classes in reserve networks has not yet been studied.2. We performed a reserve selection analysis in boreal Sweden using the Swedish National Forest Inventory plots. Seventeen structural variables were used as biodiversity indicators, and the cost of protecting each plot as a reserve was assessed using the Heureka system. A goal programming approach was applied, which allowed inclusion of several objectives and avoided a situation in which common indicators affected the result more than rare ones. The model was limited either by budget or area.3. All biodiversity indicators were found in all age classes, with more than half having the highest values in ages ≥ 100 years. Several large-tree indicators and all deadwood indicators had higher values in forests 0-14 years than in forests 15-69 years.4. It was most cost-effective to protect a large proportion of young forests since they generally have a lower net present value compared to older forests, but still contain structures of importance for biodiversity. However, it was more area-effective to protect a large proportion of old forests since they have a higher biodiversity potential per area.5. The geographical distribution of reserves selected with the budget-constrained model was strongly biassed towards the north-western section of boreal Sweden, with a large proportion of young forest, whereas the area-constrained model focussed on the south-eastern section, with dominance by the oldest age class.6.Synthesis and applications. We show that young forests with large amounts of structures important to biodiversity such as dead wood and remnant trees are cheap and cost

  3. Cost-effective age structure and geographical distribution of boreal forest reserves

    PubMed Central

    Lundström, Johanna; Öhman, Karin; Perhans, Karin; Rönnqvist, Mikael; Gustafsson, Lena; Bugman, Harald

    2011-01-01

    1. Forest reserves are established to preserve biodiversity, and to maintain natural functions and processes. Today there is heightened focus on old-growth stages, with less attention given to early successional stages. The biodiversity potential of younger forests has been overlooked, and the cost-effectiveness of incorporating different age classes in reserve networks has not yet been studied. 2. We performed a reserve selection analysis in boreal Sweden using the Swedish National Forest Inventory plots. Seventeen structural variables were used as biodiversity indicators, and the cost of protecting each plot as a reserve was assessed using the Heureka system. A goal programming approach was applied, which allowed inclusion of several objectives and avoided a situation in which common indicators affected the result more than rare ones. The model was limited either by budget or area. 3. All biodiversity indicators were found in all age classes, with more than half having the highest values in ages ≥ 100 years. Several large-tree indicators and all deadwood indicators had higher values in forests 0–14 years than in forests 15–69 years. 4. It was most cost-effective to protect a large proportion of young forests since they generally have a lower net present value compared to older forests, but still contain structures of importance for biodiversity. However, it was more area-effective to protect a large proportion of old forests since they have a higher biodiversity potential per area. 5. The geographical distribution of reserves selected with the budget-constrained model was strongly biassed towards the north-western section of boreal Sweden, with a large proportion of young forest, whereas the area-constrained model focussed on the south-eastern section, with dominance by the oldest age class. 6. Synthesis and applications. We show that young forests with large amounts of structures important to biodiversity such as dead wood and remnant trees are cheap and

  4. Growth of Cosmic Structure: Probing Dark Energy Beyond Expansion

    DOE PAGES

    Huterer, Dragan; Kirkby, David; Bean, Rachel; ...

    2014-03-15

    The quantity and quality of cosmic structure observations have greatly accelerated in recent years, and further leaps forward will be facilitated by imminent projects. These will enable us to map the evolution of dark and baryonic matter density fluctuations over cosmic history. The way that these fluctuations vary over space and time is sensitive to several pieces of fundamental physics: the primordial perturbations generated by GUT-scale physics; neutrino masses and interactions; the nature of dark matter and dark energy. We focus on the last of these here: the ways that combining probes of growth with those of the cosmic expansionmore » such as distance-redshift relations will pin down the mechanism driving the acceleration of the Universe.« less

  5. Novel Epitaxy Between Oxides and Semiconductors - Growth and Interfacial Structures

    DTIC Science & Technology

    2007-05-16

    transmission electron microscopy (HR-TEM). The interfacial chemical information has also been performed using x-ray photoelectron spectroscopy ( XPS ). The...XTEM of GaN/ Gd2O3 (24Å)/GaN(0.64μm)/Al2O3 Sapphire substrate Overgrown GaN GaN Gd2O3 Intermediate layer or nucleation layer III. Growth of GaN on c...microscopy study on a hetero-structure of GaN/ Gd2O3 (1.8nm thick)/GaN(0.64μm thick)/α-Al2O3 (sapphire). Take a note on the interface between the

  6. Growth of cosmic structure: Probing dark energy beyond expansion

    SciTech Connect

    Huterer, Dragan; Kirkby, David; Bean, Rachel; Connolly, Andrew; Dawson, Kyle; Dodelson, Scott; Evrard, August; Jain, Bhuvnesh; Jarvis, Michael; Linder, Eric; Mandelbaum, Rachel; May, Morgan; Raccanelli, Alvise; Reid, Beth; Rozo, Eduardo; Schmidt, Fabian; Sehgal, Neelima; Slosar, Anže; van Engelen, Alex; Wu, Hao-Yi; Zhao, Gongbo

    2015-03-01

    The quantity and quality of cosmic structure observations have greatly accelerated in recent years, and further leaps forward will be facilitated by imminent projects. These will enable us to map the evolution of dark and baryonic matter density fluctuations over cosmic history. The way that these fluctuations vary over space and time is sensitive to several pieces of fundamental physics: the primordial perturbations generated by GUT-scale physics; neutrino masses and interactions; the nature of dark matter and dark energy. We focus on the last of these here: the ways that combining probes of growth with those of the cosmic expansion such as distance-redshift relations will pin down the mechanism driving the acceleration of the Universe.

  7. Growth of river delta networks: Thresholds, periodicity, aging and self similarity (Invited)

    NASA Astrophysics Data System (ADS)

    Jerolmack, D. J.; Reitz, M. D.

    2010-12-01

    The surfaces of river deltas and alluvial fans (collectively fans) are often dissected by a small number of channels radiating from the fan apex. These dispersive, depositional systems do not exhibit the fractal scaling typical of erosional drainage networks. On long timescales, fan channels migrate via avulsion - the process of channel bed deposition and abandonment. What governs the selection of new flow paths, or the ultimate number of active channels, is poorly understood. Here we present results of an experimental fan that allow us to examine the growth of a depositional channel network. Flow over the fan collapses into a single channel whose dimensions adjust to threshold transport conditions for the imposed sediment load. This channelization causes localized shoreline growth, which diminishes transport capacity of the channel until the slope drops below the threshold value. This leads to deposition within the channel and widespread flooding; avulsion is completed when a new channel path is selected. This cycle is remarkably periodic, and dynamics suggest that fan slope oscillates between two thresholds - entrainment and distrainment - analogous to static and dynamic angles of repose in grain flows. Selection of a new flow path is inherently stochastic, but previously abandoned channels act as significant attractors for the flow. In the early stages of fan growth, new channels are likely to be created. Once a critical density of flow paths has been established, however, the flow oscillates among the same 3-5 channels indefinitely. These dynamics are similar to the aging phenomenon observed in the growth of fractures in brittle materials under stress. We demonstrate that a directed random walk model with memory quantitatively reproduces these dynamics and limiting behavior, and is consistent with natural fans. Because our experimental fan is built by the recurring avulsion sequence, its shoreline shape is a series of lobes that indicate persistent upstream

  8. [Weight and height local growth charts of Algerian children and adolescents (6-18 years of age)].

    PubMed

    Bahchachi, N; Dahel-Mekhancha, C C; Rolland-Cachera, M F; Badis, N; Roelants, M; Hauspie, R; Nezzal, L

    2016-04-01

    Measurements of height and weight provide important information on growth and development, puberty, and nutritional status in children and adolescents. The aim of this study was to develop contemporary reference growth centiles for Algerian children and adolescents (6-18 years of age). A cross-sectional growth survey was conducted in government schools on 7772 healthy schoolchildren (45.1% boys and 54.9% girls) aged 6-18 years in Constantine (eastern Algeria) in 2008. Height and weight were measured with portable stadiometers and calibrated scales, respectively. Smooth reference curves of height and weight were estimated with the LMS method. These height and weight curves are presented together with local data from Arab countries and with the growth references of France, Belgium (Flanders), and the World Health Organization (WHO) 2007. In girls, median height and weight increased until 16 and 17 years of age, respectively, whereas in boys, they increased through age 18 years. Between ages 11 and 13 years (puberty), girls were taller and heavier than boys. After puberty, boys became taller than girls, by up to 13 cm by the age of 18 years. Median height and weight of Algerian boys and girls were generally intermediate between those observed in other Arab countries. They were higher than the French reference values up to the age of 13 years and lower than Belgian and WHO reference values at all ages. The present study provides Algerian height- and weight-for-age growth charts, which should be recommended as a national reference for monitoring growth and development in children and adolescents.

  9. Aging Optimization of Aluminum-Lithium Alloy C458 for Application to Cryotank Structures

    NASA Technical Reports Server (NTRS)

    Sova, B. J.; Sankaran, K. K.; Babel, H.; Farahmand, B.; Rioja, R.

    2003-01-01

    Compared with aluminum alloys such as 2219, which is widely used in space vehicle for cryogenic tanks and unpressurized structures, aluminum-lithium alloys possess attractive combinations of lower density and higher modulus along with comparable mechanical properties. These characteristics have resulted in the successful use of the aluminum-lithium alloy 2195 (Al-1.0 Li-4.0 Cu-0.4 Mg-0.4 Ag-0.12 Zr) for the Space Shuttle External Tank, and the consideration of newer U.S. aluminum-lithium alloys such as L277 and C458 for future space vehicles. These newer alloys generally have lithium content less than 2 wt. % and their composition and processing have been carefully tailored to increase the toughness and reduce the mechanical property anisotropy of the earlier generation alloys such 2090 and 8090. Alloy processing, particularly the aging treatment, has a significant influence on the strength-toughness combinations and their dependence on service environments for aluminum-lithium alloys. Work at NASA Marshall Space Flight Center on alloy 2195 has shown that the cryogenic toughness can be improved by employing a two-step aging process. This is accomplished by aging at a lower temperature in the first step to suppress nucleation of the strengthening precipitate at sub-grain boundaries while promoting nucleation in the interior of the grains. Second step aging at the normal aging temperature results in precipitate growth to the optimum size. A design of experiments aging study was conducted for plate. To achieve the T8 temper, Alloy C458 (Al-1.8 Li-2.7 Cu-0.3 Mg-0.08 Zr-0.3 Mn-0.6 Zn) is typically aged at 300F for 24hours. In this study, a two-step aging treatment was developed through a comprehensive 2(exp 4) full factorial design of experiments study and the typical one-step aging used as a reference. Based on the higher lithium content of C458 compared with 2195, the first step aging temperature was varied between 175F and 250F. The second step aging temperatures was

  10. Photochemical aging of secondary organic aerosols: effects on hygroscopic growth and CCN activation

    NASA Astrophysics Data System (ADS)

    Buchholz, A.; Mentel, Th. F.; Tillmann, R.; Schlosser, E.; Mildenberger, K.; Clauss, T.; Henning, S.; Kiselev, A.; Stratmann, F.

    2009-04-01

    Plant emitted volatile organic carbons (VOCs) are a major precursor of secondary organic aerosols (SOA), an important constituent of atmospheric aerosols. The precursors are oxidized via ozonolysis, photooxidation, or by NO3 and form aerosol particles. Due to further oxidation of the organic matter the composition of the SOA may age with time. This will also change the hygroscopic growth (HG) and cloud condensation nuclei (CCN) activation of the particles. In this study we generated and aged SOA in the SAPHIR chamber at the Research Centre Juelich under near atmospheric conditions: natural sunlight, low precursor and O3 concentrations, and long reaction times. As precursor we used a mixture of 5 monoterpenes (MT) or 5 MT with 2 sesquiterpenes which had been identified as major constituents of plant emissions in previous experiments. Concentrations ranged between 4 and 100 ppb MT and the total reaction time was 36h. HG was measured at RH=10-97% by a Hygroscopic Tandem Differential Analyser (HTDMA, FZ Juelich) and at RH=97-99% by the Leipzig Aerosol Cloud Interaction Simulator (LACIS-mobile, IfT Leipzig). The agreement between HTDMA and LACIS-mobile data was generally good. CCN properties were measured with a continuous flow CCN Counter from DMT. SOA particles generated on a sunny day were more hygroscopic and had a lower activation diameter (Dcrit) than SOA formed under cloudy conditions. With aging it became more hygroscopic and Dcrit decreased. Sunlight enhanced this effect. But the change in HG and Dcrit due to aging was less than the difference between SOA generated under different conditions (i.e. sunny or cloudy). We did not observe a dependence of the HG on the precursor concentration.

  11. Growth rates and ages of deep-sea corals impacted by the Deepwater Horizon oil spill

    USGS Publications Warehouse

    Prouty, Nancy G.; Fisher, Charles R.; Demopoulos, Amanda W. J.; Druffel, Ellen R. M.

    2016-01-01

    The impact of the April 2010 Deepwater Horizon (DWH) spill on deep-sea coral communities in the Gulf of Mexico (GoM) is still under investigation, as is the potential for these communities to recover. Impacts from the spill include observation of corals covered with flocculent material, with bare skeleton, excessive mucous production, sloughing tissue, and subsequent colonization of damaged areas by hydrozoans. Information on growth rates and life spans of deep-sea corals is important for understanding the vulnerability of these ecosystems to both natural and anthropogenic perturbations, as well as the likely duration of any observed adverse impacts. We report radiocarbon ages and radial and linear growth rates based on octocorals (Paramuricea spp. and Chrysogorgia sp.) collected in 2010 and 2011 from areas of the DWH impact. The oldest coral radiocarbon ages were measured on specimens collected 11 km to the SW of the oil spill from the Mississippi Canyon (MC) 344 site: 599 and 55 cal yr BP, suggesting continuous life spans of over 600 years for Paramuricea biscaya, the dominant coral species in the region. Calculated radial growth rates, between 0.34 μm yr−1 and 14.20 μm yr−1, are consistent with previously reported proteinaceous corals from the GoM. Anomalously low radiocarbon (Δ14C) values for soft tissue from some corals indicate that these corals were feeding on particulate organic carbon derived from an admixture of modern surface carbon and a low 14C carbon source. Results from this work indicate fossil carbon could contribute 5–10% to the coral soft tissue Δ14C signal within the area of the spill impact. The influence of a low 14C carbon source (e.g., petro-carbon) on the particulate organic carbon pool was observed at all sites within 30 km of the spill site, with the exception of MC118, which may have been outside of the dominant northeast-southwest zone of impact. The quantitatively assessed extreme longevity and slow growth rates documented

  12. 75 FR 52733 - Record of Decision (ROD) for Fort Bliss Army Growth and Force Structure Realignment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-27

    ... Department of the Army Record of Decision (ROD) for Fort Bliss Army Growth and Force Structure Realignment... alternative described in the Fort Bliss Army Growth and Force Structure Realignment Final Environmental Impact... provided by growth of the installation, and a small decrease in certain quality of life indicators...

  13. The age structure of the Milky Way's halo

    NASA Astrophysics Data System (ADS)

    Carollo, D.; Beers, T. C.; Placco, V. M.; Santucci, R. M.; Denissenkov, P.; Tissera, P. B.; Lentner, G.; Rossi, S.; Lee, Y. S.; Tumlinson, J.

    2016-12-01

    We present a new, high-resolution chronographic (age) map of the Milky Way's halo, based on the inferred ages of ~130,000 field blue horizontal-branch (BHB) stars with photometry from the Sloan Digital Sky Survey. Our map exhibits a strong central concentration of BHB stars with ages greater than 12 Gyr, extending up to ~15 kpc from the Galactic Centre (reaching close to the solar vicinity), and a decrease in the mean ages of field stars with distance by 1-1.5 Gyr out to ~45-50 kpc, along with an apparent increase of the dispersion of stellar ages, and numerous known (and previously unknown) resolved over-densities and debris streams, including the Sagittarius Stream. These results agree with expectations from modern lambda cold dark matter cosmological simulations, and support the existence of a dual (inner/outer) halo system, punctuated by the presence of over-densities and debris streams that have not yet completely phase-space mixed.

  14. Placental and fetal growth restriction, size at birth and neonatal growth alter cognitive function and behaviour in sheep in an age- and sex-specific manner.

    PubMed

    Hunter, Damien S; Hazel, Susan J; Kind, Karen L; Liu, Hong; Marini, Danila; Giles, Lynne C; De Blasio, Miles J; Owens, Julie A; Pitcher, Julia B; Gatford, Kathryn L

    2015-12-01

    Intrauterine growth restriction and slow neonatal growth in humans are each associated with poorer learning, memory and cognitive flexibility in childhood and adulthood. The relative contributions of pre- and post-natal growth to cognitive outcomes are unclear, however. We therefore compared performance in learning, memory and reversal tasks using a modified Y-maze at 18 and 40 weeks of age in offspring of placentally-restricted (PR: 10 M, 13 F) and control (23 M, 17 F) ovine pregnancies. We also investigated relationships between size at birth, neonatal growth rates and cognitive outcomes. PR had limited effects on cognitive outcomes, with PR males requiring more trials to solve the initial learning task than controls (P=0.037) but faster completion of reversal tasks in both sexes at 18 weeks of age. In males, neonatal growth rate correlated inversely with numbers of trials and total time required to solve memory tasks at 40 weeks of age. In females, bleat frequency in the first reversal task at 18 weeks of age correlated positively with birth weight (r=0.734, P<0.05) and neonatal growth rate (r=0.563, P<0.05). We conclude that PR induces limited effects on cognitive outcomes in sheep, with some evidence of impaired learning in males, but little effect on memory or cognitive flexibility in either sex. Rapid neonatal growth predicted improved memory task performance in males, suggesting that strategies to optimize neonatal growth may have long-term cognitive benefits but that these may be sex-specific.

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

    USGS Publications Warehouse

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

    2008-01-01

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

  16. Demography of deep-dwelling red coral populations: Age and reproductive structure of a highly valued marine species

    NASA Astrophysics Data System (ADS)

    Priori, Cristina; Mastascusa, Vincenza; Erra, Fabrizio; Angiolillo, Michela; Canese, Simonpietro; Santangelo, Giovanni

    2013-02-01

    The valuable Mediterranean red coral Corallium rubrum (Octocorallia Gorgonacea) has been harvested for more than 2 thousand years. Although our knowledge on the demographic features of red coral populations living between 10 and 50 m depth has increased considerably in recent years, the main life-history traits of deeper populations (the main target of current harvesting) are still largely unknown. To increase the demographic knowledge of the latter populations, sampling was carried out during early Summer 2010 in the North-Western Mediterranean (Tyrrhenian Sea - Italy), between 50 and 130 m depth. This paper quantifies the main demographic descriptors of this coral population in terms of size/age and sexual structure. Colony age was estimated by counting annual growth rings on thin sections of 69 colonies. A 2-way ANOVA showed no significant difference between the age estimated by three independent observers. The average annual colony growth rate (basal diameter), showing some decrease with colony age increase, was 0.26 mm/yr. The relationship between age and basal diameter derived from a subsample of colonies was then applied to assess the age of a larger sample of the population and showed 38% of the sampled colonies reached the commercial size (≥7 mm of basal diameter), corresponding to about 30 years in this population and a maximum life span of 93 years; about half of them (51.1%) were in the 21-25 and 26-30 age classes. The analysis of the sexual features revealed a balanced sex ratio, a colony fertility of 90.3% and an average fecundity of 0.83 oocytes or planulae per polyp. The knowledge of these life-history descriptors is needed for our understanding of deep dwelling red coral population dynamics and for matching of harvesting to population growth rate.

  17. The key role of growth hormone — insulin — IGF-1 signaling in aging and cancer

    PubMed Central

    Anisimov, Vladimir N.; Bartke, Andrzej

    2014-01-01

    Studies in mammals have led to the suggestion that hyperglycemia and hyperinsulinemia are important factors in aging. GH/Insulin/insulin-like growth factor 1 (IGF-1) signaling molecules that have been linked to longevity include daf-2 and InR and their homologues in mammals, and inactivation of the corresponding genes increases lifespan in nematodes, fruit flies and mice. The life-prolonging effects of caloric restriction are likely related to decreasing IGF-1 levels. Evidence has emerged that antidiabetic drugs are promising candidates for both lifespan extension and prevention of cancer. Thus, antidiabetic drugs postpone spontaneous carcinogenesis in mice and rats, as well as chemical and radiation carcinogenesis in mice, rats and hamsters. Furthermore, metformin seems to decrease the risk for cancer in diabetic patients. PMID:23434537

  18. Fatigue Crack Growth of Age-Hardened Al Alloy Under Ultrasonic Loading

    NASA Astrophysics Data System (ADS)

    Chen, Q.; Kawagoishi, N.; Kariya, K.; Nu, Y.; Goto, M.

    An age-hardened and extruded Al alloy 7075-T6 was fatigued under both ultrasonic loading (20kHz) and rotating bending (50Hz) in the environments of controlled humidity, distilled water and oxygen gas respectively, to investigate the availability of ultrasonic fatigue test as a time-saving tool for the reliability evaluation of materials subjected to conventional frequency loading. Although fatigue strength decreased slightly at relative humidity below 60-70%, it degraded significantly when the humidity was increased beyond that level, irrespective of the loading frequency. However, the mechanisms of strength degradation involved in high humidity are quite different. Under rotating bending, fatigue strength decreased because crack growth was accelerated due to brittle fracture, whileas the decrease in fatigue strength under ultrasonic loading was caused by crack propagation transition from tensile mode to shear mode cracking.

  19. On the dynamics of the age structure, dependency, and consumption

    PubMed Central

    Hock, Heinrich

    2013-01-01

    We examine the effects of population aging due to declining fertility and rising elderly life expectancy on consumption possibilities in the presence of intergenerational transfers. Our analysis is based on a highly tractable continuous-time overlapping generations model in which the population is divided into three groups (youth dependents, workers, and elderly dependents) and lifecourse transitions take place in a probabilistic fashion. We show that the consumption-maximizing response to greater longevity in highly developed countries is an increase in fertility. However, with larger transfer payments, the actual fertility response will likely be the opposite, leading to further population aging. PMID:24353374

  20. Age and growth of the lake whitefish, Coregonus clupeaformis (Mitchill), in Lake Erie

    USGS Publications Warehouse

    Van Oosten, John; Hile, Ralph

    1949-01-01

    Although the whitefish has by no means ranked first from the standpoint of production, it has always been an important commercial species in Lake Erie. Trends in the output of whitefish have differed in the United States and Canadian waters of the lake. The 1893–1946 average annual yield of 1,201,000 pounds in the United States was only 38.3 percent of the 1879–1890 mean of 3,133,000 pounds, whereas in Canada the more recent (1907–1946) average annual take of 1,397,000 pounds has been 5.48 times the 1871–1906 mean of 255,000 pounds. The United States fishery was centered in the western part of Lake Erie (61.5 percent of the production in Michigan and Ohio) before 1921 and in the eastern part (62.6 percent in Pennsylvania and New York) in 1921–1946. The eastern part of Lake Erie (east of Port Burwell) dominated the Canadian production in 1900–1909 (65.4 percent) and in 1922–1946 (57.2 percent) but the western end was the more productive in 1871–1899 (79.8 percent) and 1910–1921 (69.7 percent). Ages were determined and individual growth histories calculated from the examination and measurement of the scales of 3,399 Lake Erie whitefish captured off four ports (Sandusky, Lorain, and Conneaut, Ohio, and Erie, Pennsylvania) over the period, 1927–1930. The number of specimens used for the investigation of other phases of the life history varied according to the amount of data available or required. Age-group III was typically (but not invariably) dominant in random samples from gear employed for the commercial production of whitefish (trap nets, pound nets, and large-mesh gill nets). The same age group also dominated most samples of the marketable catch (that is, whitefish that equalled or exceeded the minimum legal weight of 1 3/4 pounds) taken in late summer, autumn, and early winter. Age-group IV, however, was strongest among marketable fish from trap nets in early July although the III group was dominant in the random samples from the same nets

  1. The Polycomb Group Protein Pcgf1 Is Dispensable in Zebrafish but Involved in Early Growth and Aging

    PubMed Central

    Le Bourhis, Xuefen; Angrand, Pierre-Olivier

    2016-01-01

    Polycomb Repressive Complex (PRC) 1 regulates the control of gene expression programs via chromatin structure reorganization. Through mutual exclusion, different PCGF members generate a variety of PRC1 complexes with potentially distinct cellular functions. In this context, the molecular function of each of the PCGF family members remains elusive. The study of PCGF family member expression in zebrafish development and during caudal fin regeneration reveals that the zebrafish pcgf genes are subjected to different regulations and that all PRC1 complexes in terms of Pcgf subunit composition are not always present in the same tissues. To unveil the function of Pcgf1 in zebrafish, a mutant line was generated using the TALEN technology. Mutant pcgf1-/- fish are viable and fertile, but the growth rate at early developmental stages is reduced in absence of pcgf1 gene function and a significant number of pcgf1-/- fish show signs of premature aging. This first vertebrate model lacking Pcgf1 function shows that this Polycomb Group protein is involved in cell proliferation during early embryogenesis and establishes a link between epigenetics and aging. PMID:27442247

  2. Migrational changes of mesenchymal stem cells in response to cytokines, growth factors, hypoxia, and aging.

    PubMed

    Naaldijk, Yahaira; Johnson, Adiv A; Ishak, Stefan; Meisel, Hans Jörg; Hohaus, Christian; Stolzing, Alexandra

    2015-10-15

    Mesenchymal stem cells (MSCs) are non-immunogenic, multipotent cells with at least trilineage differentiation potential. They promote wound healing, improve regeneration of injured tissue, and mediate numerous other health effects. MSCs migrate to sites of injury and stimulate repair either through direct differentiation or indirectly through the stimulation of endogenous repair mechanisms. Using the in vitro scratch assay, we show that the inflammatory cytokines, chemokines, and growth factors TNF-α, SDF-1, PDGF, and bFGF enhance migration of rat MSCs under normoxic conditions, while TNF-α, IFN-γ, PDGF, and bFGF promote MSC migration under hypoxic conditions. This indicates that the oxygen concentration affects how MSCs will migrate in response to specific factors and, consistent with this, differential expression of cytokines was observed under hypoxic versus normoxic conditions. Using the transwell migration assay, we find that TNF-α, IFN-γ, bFGF, IGF-1, PDGF, and SDF-1 significantly increase transmigration of rat MSCs compared to unstimulated medium. MSCs derived from aged rats exhibited comparable migration to MSCs derived from young rats under hypoxic and normoxic conditions, even after application with specific factors. Similarly, migration in MSCs from aged, human donors did not statistically differ compared to migration in MSCs derived from human umbilical cord tissue or younger donors.

  3. Ontogeny of sexual development in the roach (Rutilus rutilus) and its interrelationships with growth and age.

    PubMed

    Paull, G C; Lange, A; Henshaw, A C; Tyler, C R

    2008-07-01

    The roach (Rutilus rutilus) has become a sentinel species for the study of sexual disruption in wild fish populations as a consequence of exposure to endocrine disrupting chemicals (EDCs). Little is known, however, about the normal ontogeny of sexual development in this species. Here, we analyzed the ontogeny of sexual development in captive-bred roach and assessed how growth rate and fish size affected the timing of both sexual differentiation and sexual development over a 2-year period. Ovarian differentiation was first recorded at 68 days post-fertilization (dpf) and this preceded testicular differentiation (first recorded at 98 dpf). In contrast, sexual maturation occurred at an earlier age in males (300 dpf) compared with females (728 dpf). No differences in body size (length or weight) were recorded between male and female roach until the fish were 415 dpf. Studies on three populations of roach which grew at different rates showed that the timing of sexual differentiation was highly variable and more related to fish size than to fish age. Time to sexual maturation was also variable among populations but, subsequent to their first year of life, gonadal status was less well associated with fish size. Interestingly, the sex ratio of the population was biased towards females in populations that grew more rapidly during early life. The findings presented here provide a valuable foundation of work to support both field- and laboratory-based assessments on the effects of EDCs, and other stressors, on sexual differentiation and development in the roach.

  4. The Frontal Hypothesis of Cognitive Aging: Factor Structure and Age Effects on Four "Frontal Tests" among Healthy Individuals

    ERIC Educational Resources Information Center

    Rodriguez-Aranda, Claudia; Sundet, Kjetil

    2006-01-01

    With 101 healthy aging adult participants, the authors investigated whether executive functions are a unitary concept. The authors established the factor structure of the Wisconsin Card Sorting Test (WCST; E. A. Berg, 1948), the Stroop color and word test (C. J. Golden, 1978), verbal fluency using the Controlled Oral Word Association Test (COWAT;…

  5. 15 CFR 50.5 - Fee structure for age search and citizenship information.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 15 Commerce and Foreign Trade 1 2011-01-01 2011-01-01 false Fee structure for age search and... THE CENSUS § 50.5 Fee structure for age search and citizenship information. Type of service Fee Searches of one census for one person and one transcript $65.00 Each additional copy of census transcript...

  6. Cardiological aging in SAM model: effect of chronic treatment with growth hormone.

    PubMed

    Forman, K; Vara, E; García, C; Ariznavarreta, C; Escames, G; Tresguerres, J A F

    2010-06-01

    The purpose of this study was to investigate the effect of aging on different parameters related to inflammation, oxidative stress and apoptosis in hearts from two types of male mice models: senescence-accelerated mice (SAM-P8) and senescence-accelerated-resistant (SAM-R1), and the influence of chronic administration of Growth Hormone (GH) on old SAM-P8 mice. Forty male mice were used. Animals were divided into five experimental groups: two 10 month old untreated groups (SAM-P8/SAM-R1), two 2 month old young groups (SAM-P8/SAM-R1) and one 10 month old group (SAM-P8) treated with GH for 30 days. The expression of tumor necrosis factor-alpha, interleukin 1, interleukin 10, heme oxygenases 1 and 2, endothelial and inducible nitric oxide synthases, NFkB, Bad, Bax and Bcl-2 were determined by real-time reverse transcription polymerase chain reaction (RT-PCR). Results were submitted to a two way ANOVA statistical evaluation using the Statgraphics program. Inflammation, as well as, oxidative stress and apoptosis markers were increased in the heart of old SAM-P8 males, as compared to young controls and this situation was not observed in the old SAM-R1 mice. Exogenous GH administration reverted the effect of aging in the described parameters of old SAM-P8 mice. Our results suggest that inflammation, apoptosis and oxidative stress could play an important role in the observed cardiovascular alterations related to aging of SAM-P8 mice and that GH may play a potential protective effect on the cardiovascular system of these animals.

  7. Adaptation of Drosophila melanogaster to Unfavorable Growth Medium Affects Lifespan and Age-Related Fecundity.

    PubMed

    Yakovleva, E U; Naimark, E B; Markov, A V

    2016-12-01

    Experimental adaptation of Drosophila melanogaster to nutrient-deficient starch-based (S) medium resulted in lifespan shortening, increased early-life fecundity, accelerated reproductive aging, and sexually dimorphic survival curves. The direction of all these evolutionary changes coincide with the direction of phenotypic plasticity observed in non-adapted flies cultured on S medium. High adult mortality rate caused by unfavorable growth medium apparently was the main factor of selection during the evolutionary experiment. The results are partially compatible with Williams' hypothesis, which states that increased mortality rate should result in relaxed selection against mutations that decrease fitness late in life, and thus promote the evolution of shorter lifespan and earlier reproduction. However, our results do not confirm Williams' prediction that the sex with higher mortality rate should undergo more rapid aging: lifespan shortening by S medium is more pronounced in naïve males than females, but it was female lifespan that decreased more in the course of adaptation. These data, as well as the results of testing of F1 hybrids between adapted and control lineages, are compatible with the idea that the genetic basis of longevity is different in the two sexes, and that evolutionary response to increased mortality rate depends on the degree to which the mortality is selective. Selective mortality can result in the development of longer (rather than shorter) lifespan in the course of evolution. The results also imply that antagonistic pleiotropy of alleles, which increase early-life fecundity at the cost of accelerated aging, played an important role in the evolutionary changes of females in the experimental lineage, while accumulation of deleterious mutations with late-life effects due to drift was more important in the evolution of male traits.

  8. Age, genotype and sex effects on growth performance of local chickens kept under improved management in Ghana.

    PubMed

    Osei-Amponsah, Richard; Kayang, Boniface B; Naazie, Augustine

    2012-01-01

    Characterisation of animal genetic resources has been recognised globally as an important step towards their sustainable use. Body weight data of local chickens (213 forest and 160 savannah chickens) and 183 French free-ranging SASSO T44 chickens kept under improved management were collected from hatch to 40 weeks of age and analysed to determine the effects of age, genotype and sex on their growth performance. At all ages, SASSO T44 chickens had significantly (P<0.05) higher weights (2.6-3.2 kg at 28 weeks) than the local chickens (1.2-1.7 kg at 28 weeks). The rate of growth at the earlier ages in the local genotypes (5.57-7.80 g/day) was lower than the range of 13.81-15.42 in SASSO T44 chickens. Except at hatch, savannah chickens were significantly heavier (P<0.05) than the forest chickens at all ages. Male chickens had significantly (P<0.05) superior growth rates than females across all genotypes except from the 20th to the 28th week. Growth trends in both sexes depicted linear increase in body weights; however, the rate of increase in body weights was higher in males as compared to females, thus showing clear sexual dimorphism. There were no significant (P>0.05) differences in the growth rates of SASSO T44 chickens and local genotypes at the later ages (20-28 weeks). Local chickens from the savannah zone had better growth rate than forest chickens. The significant effect of ecozone on the growth potential of local chickens is an indication that their productive potential could be improved through interventions in the environment such as provision of feed and some veterinary care.

  9. Genetic regulation of growth in height and weight from 3 to 12 years of age: a longitudinal study of Dutch twin children.

    PubMed

    Silventoinen, Karri; Bartels, Meike; Posthuma, Daniëlle; Estourgie-van Burk, G Frederiek; Willemsen, Gonneke; van Beijsterveldt, Toos C E M; Boomsma, Dorret I

    2007-04-01

    Human growth is a complex and poorly understood process. We studied the effect of genetic and environmental factors on height and body mass index (BMI, kg/m(2)) based on maternal reports at 3, 4, 5, 7, 10 and 12 years of age in a large longitudinal cohort of Dutch twins (7755 complete twin pairs at age 3). Several multivariate variance component models for twins were fitted to the data using the Mx statistical package. The first-born twin was taller until age 10 and heavier until age 12 than the second-born co-twin. Heritability estimates were high for height (a(2) = .58-.91) and BMI (a(2) = .31-.82), but common and unshared environmental factors were also important. The phenotypic correlations across the ages for height and BMI were mainly explained by correlated additive genetic factors (r(a) = .77-.96 for height and .43-.92 for BMI), but common (r(c) = .40-.84 and .09-.78, respectively) and specific environmental correlations (r(e) = .50-.81 and .42-.80, respectively) were also significant. Additive genetic factors decreased with increasing age difference for both height and BMI. However, the full Cholesky model, which does not make any assumptions regarding the underlying genetic structure, had the best fit. High genetic correlations across the ages, especially for height, may help further molecular genetic studies of human growth. Environmental factors affecting height and BMI during growth period are also important, and further studies are needed to identify these factors and test whether they interact with genetic factors.

  10. Age structure and mortality of walleyes in Kansas reservoirs: Use of mortality caps to establish realistic management objectives

    USGS Publications Warehouse

    Quist, M.C.; Stephen, J.L.; Guy, C.S.; Schultz, R.D.

    2004-01-01

    Age structure, total annual mortality, and mortality caps (maximum mortality thresholds established by managers) were investigated for walleye Sander vitreus (formerly Stizostedion vitreum) populations sampled from eight Kansas reservoirs during 1991-1999. We assessed age structure by examining the relative frequency of different ages in the population; total annual mortality of age-2 and older walleyes was estimated by use of a weighted catch curve. To evaluate the utility of mortality caps, we modeled threshold values of mortality by varying growth rates and management objectives. Estimated mortality thresholds were then compared with observed growth and mortality rates. The maximum age of walleyes varied from 5 to 11 years across reservoirs. Age structure was dominated (???72%) by walleyes age 3 and younger in all reservoirs, corresponding to ages that were not yet vulnerable to harvest. Total annual mortality rates varied from 40.7% to 59.5% across reservoirs and averaged 51.1% overall (SE = 2.3). Analysis of mortality caps indicated that a management objective of 500 mm for the mean length of walleyes harvested by anglers was realistic for all reservoirs with a 457-mm minimum length limit but not for those with a 381-mm minimum length limit. For a 500-mm mean length objective to be realized for reservoirs with a 381-mm length limit, managers must either reduce mortality rates (e.g., through restrictive harvest regulations) or increase growth of walleyes. When the assumed objective was to maintain the mean length of harvested walleyes at current levels, the observed annual mortality rates were below the mortality cap for all reservoirs except one. Mortality caps also provided insight on management objectives expressed in terms of proportional stock density (PSD). Results indicated that a PSD objective of 20-40 was realistic for most reservoirs. This study provides important walleye mortality information that can be used for monitoring or for inclusion into

  11. Climatic Stress during Stand Development Alters the Sign and Magnitude of Age-Related Growth Responses in a Subtropical Mountain Pine.

    PubMed

    Ruiz-Benito, Paloma; Madrigal-González, Jaime; Young, Sarah; Mercatoris, Pierre; Cavin, Liam; Huang, Tsurng-Juhn; Chen, Jan-Chang; Jump, Alistair S

    2015-01-01

    The modification of typical age-related growth by environmental changes is poorly understood, In part because there is a lack of consensus at individual tree level regarding age-dependent growth responses to climate warming as stands develop. To increase our current understanding about how multiple drivers of environmental change can modify growth responses as trees age we used tree ring data of a mountain subtropical pine species along an altitudinal gradient covering more than 2,200 m of altitude. We applied mixed-linear models to determine how absolute and relative age-dependent growth varies depending on stand development; and to quantify the relative importance of tree age and climate on individual tree growth responses. Tree age was the most important factor for tree growth in models parameterised using data from all forest developmental stages. Contrastingly, the relationship found between tree age and growth became non-significant in models parameterised using data corresponding to mature stages. These results suggest that although absolute tree growth can continuously increase along tree size when trees reach maturity age had no effect on growth. Tree growth was strongly reduced under increased annual temperature, leading to more constant age-related growth responses. Furthermore, young trees were the most sensitive to reductions in relative growth rates, but absolute growth was strongly reduced under increased temperature in old trees. Our results help to reconcile previous contrasting findings of age-related growth responses at the individual tree level, suggesting that the sign and magnitude of age-related growth responses vary with stand development. The different responses found to climate for absolute and relative growth rates suggest that young trees are particularly vulnerable under warming climate, but reduced absolute growth in old trees could alter the species' potential as a carbon sink in the future.

  12. Normative and Structural Perspectives on Age in a Work Organization,

    DTIC Science & Technology

    1983-12-01

    Professional Apprentice: Observations on Fieldwork Roles in Two Organizational Settings." In S.B. Bacharach (ed.), Research in Organizational Sociology...Career: Its Meaning, Its Satisfactions, Its Difficulties." In press: Journal of Occupational Behavior. November, 1982. TR-12 Schein, Edgar H. "The Role of...behavior because the distribution of ages within a social group constrains the roles and statuse; allocated to members. The scarcity of young marriageable

  13. Who Ate Whom: Population Dynamics With Age-Structured Predation

    DTIC Science & Technology

    2010-10-15

    competes for food. Werner and Gilliam [2] review many examples of ecosystems in which competitive and predatory relationships are age- and size-dependent. As...of reproduction in that it transfers biomass from tadpoles to frogs, though it is certainly not identical. We have not fully explored the relationship ...limit cycles, though the limit cycles are not robust and rather unrealistic biologically, so in this model the two species are completely codependent

  14. Type I collagen aging impairs discoidin domain receptor 2-mediated tumor cell growth suppression.

    PubMed

    Saby, Charles; Buache, Emilie; Brassart-Pasco, Sylvie; El Btaouri, Hassan; Courageot, Marie-Pierre; Van Gulick, Laurence; Garnotel, Roselyne; Jeannesson, Pierre; Morjani, Hamid

    2016-05-03

    Tumor cells are confronted to a type I collagen rich environment which regulates cell proliferation and invasion. Biological aging has been associated with structural changes of type I collagen. Here, we address the effect of collagen aging on cell proliferation in a three-dimensional context (3D).We provide evidence for an inhibitory effect of adult collagen, but not of the old one, on proliferation of human fibrosarcoma HT-1080 cells. This effect involves both the activation of the tyrosine kinase Discoidin Domain Receptor 2 (DDR2) and the tyrosine phosphatase SHP-2. DDR2 and SHP-2 were less activated in old collagen. DDR2 inhibition decreased SHP-2 phosphorylation in adult collagen and increased cell proliferation to a level similar to that observed in old collagen.In the presence of old collagen, a high level of JAK2 and ERK1/2 phosphorylation was observed while expression of the cell cycle negative regulator p21CIP1 was decreased. Inhibition of DDR2 kinase function also led to an increase in ERK1/2 phosphorylation and a decrease in p21CIP1 expression. Similar signaling profile was observed when DDR2 was inhibited in adult collagen. Altogether, these data suggest that biological collagen aging could increase tumor cell proliferation by reducingthe activation of the key matrix sensor DDR2.

  15. Growth, Characterization, and Simulation of Novel Semiconductor Tunnel Structures.

    NASA Astrophysics Data System (ADS)

    Chow, David Hsingkuo

    This thesis presents investigations of novel semiconductor heterostructure devices based on quantum mechanical tunneling. Due to their small characteristic dimensions, these devices have extremely fast charge transport properties. Thus, it is expected that tunnel structure devices will be well -suited to high frequency and optoelectronic applications. In chapter 2, a theoretical model is developed to simulate tunneling currents in single barrier heterostructures. The model includes band bending effects and a two band treatment of electron attenuation coefficients in the barrier. It is proposed that certain material systems have the appropriate band alignments to realize a novel single barrier negative differential resistance (NDR) mechanism. A thorough theoretical analysis of these single barrier NDR structures is presented. The first experimental demonstration of the single barrier NDR mechanism is reported in chapter 3. The HgTe/CdTe material system was selected for the demonstration. In this material system, low temperatures (<20 K) are needed to observe the NDR effect. High temperature (190-300 K) current-voltage curves from the single barrier Hg_{1-x}Cd_ {x}Te heterostructures have also been investigated, leading to a direct electrical measurement of the controversial HgTe/CdTe valence band offset. In chapter 4, results are presented from several studies of III-V heterostructures grown by molecular beam epitaxy. A measurement of the GaAs/AlAs valence band offset by x-ray photoemmision spectroscopy yields a value of 0.46 +/- 0.07 eV, independent of growth sequence. Optical measurements of electron tunneling times in GaAs/AlAs double barrier heterostructures are performed by growing structures with very thin cap layers. Tunneling times as short as ~12 ps are measured. Triple barrier GaAs/AlAs tunnel structures are found to display strong NDR, indicating that the tunneling process is coherent (as opposed to sequential) in nature. Finally, a technique for

  16. Age structure of refractory interstellar dust and isotopic consequences

    NASA Technical Reports Server (NTRS)

    Clayton, Donald D.; Scowen, Paul; Liffman, Kurt

    1989-01-01

    A sputtering and recycling Monte Carlo model, developed by Liffman and Clayton (1988) is used to calculate the distribution of existence times of the matter in interstellar dust composed of refractory metals. The mean age of each dust particle is defined not as the time it has existed but rather as the mass-weighted existence times of its parts at t = 6 Gyr of the modeled solar system formation. It is shown that Galactic evolution generates a mean correlation, applying to large numbers of particles binned according to size rather than according to individual particles, whose mean ages fluctuate statistically. The cosmochemical consequence is that if interstellar particles can be dynamically sorted into separate size populations during the aggregation history of solar system bodies, the collections of larger grains will constitute matter that is chemically older than collections of smaller grains. The macroscopic age difference generates isotopic anomalies by virtue of the time dependence of the secondary/primary nucleosynthesis yields. Results are compared with three different prescriptions for the sputtering of interstellar dust.

  17. Nanoscale Structure, Dynamics, and Aging Behavior of Metallic Glass Thin Films

    PubMed Central

    Burgess, J. A. J.; Holt, C. M. B.; Luber, E. J.; Fortin, D. C.; Popowich, G.; Zahiri, B.; Concepcion, P.; Mitlin, D.; Freeman, M. R.

    2016-01-01

    Scanning tunnelling microscopy observations resolve the structure and dynamics of metallic glass Cu100−xHfx films and demonstrate scanning tunnelling microscopy control of aging at a metallic glass surface. Surface clusters exhibit heterogeneous hopping dynamics. Low Hf concentration films feature an aged surface of larger, slower clusters. Argon ion-sputtering destroys the aged configuration, yielding a surface in constant fluctuation. Scanning tunnelling microscopy can locally restore the relaxed state, allowing for nanoscale lithographic definition of aged sections. PMID:27498698

  18. [Effects of crop tree release on stand growth and stand structure of Cunninghamia lanceolata plantation].

    PubMed

    Wu, Jian-qiang; Wang, Yi-xiang; Yang, Yi; Zhu, Ting-ting; Zhu, Xu-dan

    2015-02-01

    Crop trees were selected in a 26-year-old even-aged Cunninghamia lanceolata plantation in Lin' an, and compared in plots that were released and unreleased to examine growth and structure responses for 3 years after thinning. Crop tree release significantly increased the mean increments of diameter and volume of individual tree by 1.30 and 1.25 times relative to trees in control stands, respectively. The increments of diameter and volume of crop trees were significantly higher than those of general trees in thinning plots, crop trees and general trees in control plots, which suggested that the responses from different tree types to crop tree release treatment were different. Crop tree release increased the average distances of crop trees to the nearest neighboring trees, reducing competition among crop trees by about 68.2%. 3-year stand volume increment for thinning stands had no significant difference with that of control stands although the number of trees was only 81.5% of the control. Crop trees in thinned plots with diameters over than 14 cm reached 18.0% over 3 years, compared with 12.0% for trees without thinning, suggesting that crop tree release benefited the larger individual trees. The pattern of tree locations in thinning plots tended to be random, complying with the rule that tree distribution pattern changes with growth. Crop tree release in C. lanceolata plantation not only promoted the stand growth, but also optimized the stand structure, benefiting crop trees sustained rapid growth and larger diameter trees production.

  19. Analytical developments in support of the NASA aging aircraft program with an application to crack growth from rivets

    NASA Astrophysics Data System (ADS)

    Swenson, Daniel; Gondhalekar, Sudhir; Dawicke, Dave

    The NASA Airframe Structural Integrity Program is a multi-disciplinary program to develop analysis methodology, a fracture data base, and improved methods of nondestructive evaluation (NDE) detection of disbonds and cracks. As part of this program, analysis tools to predict crack growth rates and fracture propagation in shell structures are being developed. This paper describes a finite element model of crack growth in layered structures, such as lap splice joints. The model is developed using separate two-dimensional meshes of individual layers which can overlap in space. These layers can be connected with either rivit elements or by adhesive elements. Cracks can be modeled in any layer, with automatic remeshing during crack growth. Using the model, an investigation was made of the effect of rivet interference on fatigue crack growth from a loaded rivit hole. It was found that the interference reduced the stress intensity factor range significantly, resulting in slower crack growth.

  20. Polypeptide Chirality Influences Multilayer Thin Film Growth and Structure

    NASA Astrophysics Data System (ADS)

    Bell, Zephra; Khadka, Dhan; Haynie, Donald

    2011-03-01

    Polypeptide multilayer thin films are being developed for a variety of applications.These include coatings for implant devices and systems for drug delivery in thebiomedical sciences, and optical coatings. Subsequent polymer adsorption steps involve polymers of opposite polarity. Here, the polymers were polypeptides. This project compared the consequences of changing polypeptide chirality on film growth and structure. The peptides were poly(L-glutamic acid), its right-handed counterpart, poly(D-glutamic acid), and poly(lysine-tyrosine). The first two are negatively charged at neutral pH, the third one is positively charged. Poly(lysine-tyrosine)/poly(L-glutamic acid) films and poly(lysine-tyrosine)/poly(D-glutamic acid) films werefabricated on 1 mm-thick quartz plates. In one experiment, films were grown to 34layers. The UV absorption spectrum was taken after each layer deposited to determinethe rate of polymer self-assembly. Separately, UV or visible wavelength spectra wereobtained for films stained with a dye cooled/heated in the range 4-65 °C. In anotherexperiment, a mixture of poly-L-glutamic acid and poly-D-glutamic acid was used as thepolyanion for film buildup. The data show that poly(lysine-tyrosine)/poly(L-glutamicacid) films built up at a higher rate than the corresponding right-handed films.

  1. A tropical freshwater wetlands: I. Structure, growth, and regeneration

    USGS Publications Warehouse

    Allen, J.A.; Krauss, K.W.; Ewel, K.C.; Keeland, B.D.; Waguk, E.E.

    2005-01-01

    Forested wetlands dominated by Terminalia carolinensis are endemic to Micronesia but common only on the island of Kosrae, Federated States of Micronesia. On Kosrae, these forests occur on Nansepsep, Inkosr, and Sonahnpil soil types, which differ in degree of flooding and soil saturation. We compared forest structure, growth, nutrition, and regeneration on two sites each on Nansepsep and Inkosr soils and one site on the much less common Sonahnpil soil type. Terminalia tree sizes were similar on all three soil types, but forests differed in total basal area, species of smaller trees, and total plant species diversity. Terminalia regeneration was found only on the Inkosr soil type, which had the highest water table levels. Other Terminalia species are relatively light demanding, and T. carolinensis exhibited similar characteristics. It is therefore likely that Terminalia requires periodic, but perhaps naturally rare, stand-replacing disturbances (e.g., typhoons) in order to maintain its dominanace, except on the wettest sites, where competition from other species is reduced. Terminalia swamps in the Nansepsep soil type appeared to be at the greatest risk of conversion to other uses, but swamps on all three types may face reater pressure as Kosrae's population increases and the island's infrastrucure becomes more developed.

  2. Targeting vaccination against novel infections: risk, age and spatial structure for pandemic influenza in Great Britain

    PubMed Central

    Keeling, Matt J.; White, Peter J.

    2011-01-01

    The emergence of a novel strain of H1N1 influenza virus in Mexico in 2009, and its subsequent worldwide spread, has focused attention to the question of optimal deployment of mass vaccination campaigns. Here, we use three relatively simple models to address three issues of primary concern in the targeting of any vaccine. The advantages of such simple models are that the underlying assumptions and effects of individual parameters are relatively clear, and the impact of uncertainty in the parametrization can be readily assessed in the early stages of an outbreak. In particular, we examine whether targeting risk-groups, age-groups or spatial regions could be optimal in terms of reducing the predicted number of cases or severe effects; and how these targeted strategies vary as the epidemic progresses. We examine the conditions under which it is optimal to initially target vaccination towards those individuals within the population who are most at risk of severe effects of infection. Using age-structured mixing matrices, we show that targeting vaccination towards the more epidemiologically important age groups (5–14 year olds and then 15–24 year olds) leads to the greatest reduction in the epidemic growth and hence reduces the total number of cases. Finally, we consider how spatially targeting the vaccine towards regions of country worst affected could provide an advantage. We discuss how all three of these priorities change as both the speed at which vaccination can be deployed and the start of the vaccination programme is varied. PMID:20943682

  3. Healthy aging and myocardium: A complicated process with various effects in cardiac structure and physiology.

    PubMed

    Nakou, E S; Parthenakis, F I; Kallergis, E M; Marketou, M E; Nakos, K S; Vardas, P E

    2016-04-15

    It is known that there is an ongoing increase in life expectancy worldwide, especially in the population older than 65years of age. Cardiac aging is characterized by a series of complex pathophysiological changes affecting myocardium at structural, cellular, molecular and functional levels. These changes make the aged myocardium more susceptible to stress, leading to a high prevalence of cardiovascular diseases (heart failure, atrial fibrillation, left ventricular hypertrophy, coronary artery disease) in the elderly population. The aging process is genetically programmed but modified by environmental influences, so that the rate of aging can vary widely among people. We summarized the entire data concerning all the multifactorial changes in aged myocardium and highlighting the recent evidence for the pathophysiological basis of cardiac aging. Keeping an eye on the clinical side, this review will explore the potential implications of the age-related changes in the clinical management and on novel therapeutic strategies potentially deriving from the scientific knowledge currently acquired on cardiac aging process.

  4. Radiostratigraphy and age structure of the Greenland Ice Sheet.

    PubMed

    MacGregor, Joseph A; Fahnestock, Mark A; Catania, Ginny A; Paden, John D; Prasad Gogineni, S; Young, S Keith; Rybarski, Susan C; Mabrey, Alexandria N; Wagman, Benjamin M; Morlighem, Mathieu

    2015-02-01

    Several decades of ice-penetrating radar surveys of the Greenland and Antarctic ice sheets have observed numerous widespread internal reflections. Analysis of this radiostratigraphy has produced valuable insights into ice sheet dynamics and motivates additional mapping of these reflections. Here we present a comprehensive deep radiostratigraphy of the Greenland Ice Sheet from airborne deep ice-penetrating radar data collected over Greenland by The University of Kansas between 1993 and 2013. To map this radiostratigraphy efficiently, we developed new techniques for predicting reflection slope from the phase recorded by coherent radars. When integrated along track, these slope fields predict the radiostratigraphy and simplify semiautomatic reflection tracing. Core-intersecting reflections were dated using synchronized depth-age relationships for six deep ice cores. Additional reflections were dated by matching reflections between transects and by extending reflection-inferred depth-age relationships using the local effective vertical strain rate. The oldest reflections, dating to the Eemian period, are found mostly in the northern part of the ice sheet. Within the onset regions of several fast-flowing outlet glaciers and ice streams, reflections typically do not conform to the bed topography. Disrupted radiostratigraphy is also observed in a region north of the Northeast Greenland Ice Stream that is not presently flowing rapidly. Dated reflections are used to generate a gridded age volume for most of the ice sheet and also to determine the depths of key climate transitions that were not observed directly. This radiostratigraphy provides a new constraint on the dynamics and history of the Greenland Ice Sheet.

  5. Radiostratigraphy and age structure of the Greenland Ice Sheet

    PubMed Central

    MacGregor, Joseph A; Fahnestock, Mark A; Catania, Ginny A; Paden, John D; Prasad Gogineni, S; Young, S Keith; Rybarski, Susan C; Mabrey, Alexandria N; Wagman, Benjamin M; Morlighem, Mathieu

    2015-01-01

    Several decades of ice-penetrating radar surveys of the Greenland and Antarctic ice sheets have observed numerous widespread internal reflections. Analysis of this radiostratigraphy has produced valuable insights into ice sheet dynamics and motivates additional mapping of these reflections. Here we present a comprehensive deep radiostratigraphy of the Greenland Ice Sheet from airborne deep ice-penetrating radar data collected over Greenland by The University of Kansas between 1993 and 2013. To map this radiostratigraphy efficiently, we developed new techniques for predicting reflection slope from the phase recorded by coherent radars. When integrated along track, these slope fields predict the radiostratigraphy and simplify semiautomatic reflection tracing. Core-intersecting reflections were dated using synchronized depth-age relationships for six deep ice cores. Additional reflections were dated by matching reflections between transects and by extending reflection-inferred depth-age relationships using the local effective vertical strain rate. The oldest reflections, dating to the Eemian period, are found mostly in the northern part of the ice sheet. Within the onset regions of several fast-flowing outlet glaciers and ice streams, reflections typically do not conform to the bed topography. Disrupted radiostratigraphy is also observed in a region north of the Northeast Greenland Ice Stream that is not presently flowing rapidly. Dated reflections are used to generate a gridded age volume for most of the ice sheet and also to determine the depths of key climate transitions that were not observed directly. This radiostratigraphy provides a new constraint on the dynamics and history of the Greenland Ice Sheet. Key Points Phase information predicts reflection slope and simplifies reflection tracing Reflections can be dated away from ice cores using a simple ice flow model Radiostratigraphy is often disrupted near the onset of fast ice flow PMID:26213664

  6. Vascularisation and osteochondrosis of the epiphyseal growth cartilage of the distal femur in pigs--development with age, growth rate, weight and joint shape.

    PubMed

    Ytrehus, B; Carlson, C S; Lundeheim, N; Mathisen, L; Reinholt, F P; Teige, J; Ekman, S

    2004-03-01

    Until recently, the cartilage canals of the epiphyseal growth cartilage have not been associated with any specific disease. However, data support the hypothesis that osteochondrosis could be related to inadequate blood supply from vessels in these channels. We have done a study to investigate the relationship between the regression of cartilage canals and the formation of osteochondrosis latens in the epiphyseal growth cartilage of the distal femur in pigs, and the relationship between these events and age, growth rate, weight and femoral shape of the individual animals. This involved, in part, a comprehensive study of the distribution and pattern of regression of the cartilage canals. We found that the regression is a highly predictable process that follows an age-dependent pattern. However, we failed to prove any association between overall vascular regression and osteochondrosis, between vascular regression and weight, growth rate or femoral shape or between osteochondrosis and weight, growth rate or femoral shape. This may indicate that osteochondrosis latens is not caused by a general failure of vascular supply or general factors such as growth rate, but rather a consequence of local conditions affecting a limited number of vessels. A factor fitting this description is local compression.

  7. Parasitism in Children Aged Three Years and Under: Relationship between Infection and Growth in Rural Coastal Kenya

    PubMed Central

    McKibben, Maxim; Mungai, Peter; Muchiri, Eric M.; McKibben, Elisabeth; Gildengorin, Ginny; Sutherland, Laura J.; King, Charles H.; King, Christopher L.; Malhotra, Indu

    2015-01-01

    Background Parasitic infections, which are among the most common infections worldwide, disproportionately affect children; however, little is known about the impact of parasitic disease on growth in very early childhood. Our objective was to document the prevalence of parasitic infections and examine their association with growth during the first three years of life among children in coastal Kenya. Methodology/Principal Findings Children enrolled in a maternal-child cohort were tested for soil transmitted helminths (STHs: Ascaris, Trichuris, hookworm, Strongyloides), protozoa (malaria, Entamoeba histolytica and Giardia lamblia), filaria, and Schistosoma infection every six months from birth until age three years. Anthropometrics were measured at each visit. We used generalized estimating equation (GEE) models to examine the relationship between parasitic infections experienced in the first three years of life and growth outcomes (weight, length and head circumference). Of 545 children, STHs were the most common infection with 106 infections (19%) by age three years. Malaria followed in period prevalence with 68 infections (12%) by three years of age. Filaria and Schistosoma infection occurred in 26 (4.8%) and 16 (2.9%) children, respectively. Seven percent were infected with multiple parasites by three years of age. Each infection type (when all STHs were combined) was documented by six months of age. Decreases in growth of weight, length and head circumference during the first 36 months of life were associated with hookworm, Ascaris, E. histolytica, malaria and Schistosoma infection. In a subset analysis of 180 children who followed up at every visit through 24 months, infection with any parasite was associated with decelerations in weight, length and head circumference growth velocity. Multiple infections were associated with greater impairment of linear growth. Conclusions/Significance Our results demonstrate an under-recognized burden of parasitism in the first

  8. Brain growth of the domestic pig (Sus scrofa) from 2 to 24 weeks of age: a longitudinal MRI study.

    PubMed

    Conrad, Matthew S; Dilger, Ryan N; Johnson, Rodney W

    2012-01-01

    An animal model with brain growth similar to humans, that can be used in MRI studies to investigate brain development, would be valuable. Our laboratory has developed and validated MRI methods for regional brain volume quantification in the neonatal piglet. The aim of this study was to utilize the MRI-based volume quantification technique in a longitudinal study to determine brain growth in domestic pigs from 2 to 24 weeks of age. MRI data were acquired from pigs 2-24 weeks of age using a 3-dimensional magnetization-prepared gradient echo sequence on a Magnetom Trio 3-tesla imager. Manual segmentation was performed for volume estimates of total brain, cortical, diencephalon, brainstem, cerebellar and hippocampal regions. Logistic modeling procedures were used to characterize brain growth. Total brain volume increased 130% (±12%) and 121% (±7%) from 2 to 24 weeks in males and females, respectively. The maximum increase in total brain volume occurred about the age of 4 weeks and 95% of whole brain growth occurred by the age of 21-23 weeks. Logistical modeling suggests there are sexually dimorphic effects on brain growth. For example, in females, the cortex was smaller (p = 0.04). Furthermore, the maximum growth of the hippocampus occurred about 5 weeks earlier in females than males, and the window for hippocampal growth was significantly shorter in females than males (p = 0.02, p = 0.002 respectively). These sexual dimorphisms are similar to what is seen in humans. In addition to providing important data on brain growth for pigs, this study shows pigs can be used to obtain longitudinal MRI data. The large increase in brain volume in the postnatal period is similar to that of human neonates and suggests pigs can be used to investigate brain development.

  9. Quantitative image analysis reveals distinct structural transitions during aging in Caenorhabditis elegans tissues.

    PubMed

    Johnston, Josiah; Iser, Wendy B; Chow, David K; Goldberg, Ilya G; Wolkow, Catherine A

    2008-07-30

    Aging is associated with functional and structural declines in many body systems, even in the absence of underlying disease. In particular, skeletal muscles experience severe declines during aging, a phenomenon termed sarcopenia. Despite the high incidence and severity of sarcopenia, little is known about contributing factors and development. Many studies focus on functional aspects of aging-related tissue decline, while structural details remain understudied. Traditional approaches for quantifying structural changes have assessed individual markers at discrete intervals. Such approaches are inadequate for the complex changes associated with aging. An alternative is to consider changes in overall morphology rather than in specific markers. We have used this approach to quantitatively track tissue architecture during adulthood and aging in the C. elegans pharynx, the neuromuscular feeding organ. Using pattern recognition to analyze aged-grouped pharynx images, we identified discrete step-wise transitions between distinct morphologies. The morphology state transitions were maintained in mutants with pharynx neurotransmission defects, although the pace of the transitions was altered. Longitudinal measurements of pharynx function identified a predictive relationship between mid-life pharynx morphology and function at later ages. These studies demonstrate for the first time that adult tissues undergo distinct structural transitions reflecting postdevelopmental events. The processes that underlie these architectural changes may contribute to increased disease risk during aging, and may be targets for factors that alter the aging rate. This work further demonstrates that pattern analysis of an image series offers a novel and generally accessible approach for quantifying morphological changes and identifying structural biomarkers.

  10. The 1991 International Conference on Aging Aircraft and Structural Airworthiness

    NASA Technical Reports Server (NTRS)

    Harris, Charles E. (Editor)

    1992-01-01

    Technical sessions of the conference included structural performance, nondestructive evaluation, maintenance and repair, international activities, and commuter airlines. Each session was organized to provide a well-rounded view of the subject from the industry, regulatory, and research perspective. Thirty-four presentations were given by the international technical community.

  11. Secular Trends in Growth and Nutritional Status of Mozambican School-Aged Children and Adolescents

    PubMed Central

    dos Santos, Fernanda Karina; Maia, José A. R.; Gomes, Thayse Natacha Q. F.; Daca, Timóteo; Madeira, Aspacia; Katzmarzyk, Peter T.; Prista, António

    2014-01-01

    Objectives The purpose of this study was to examine secular changes in growth and nutritional status of Mozambican children and adolescents between 1992, 1999 and 2012. Methods 3374 subjects (1600 boys, 1774 girls), distributed across the three time points (523 subjects in 1992; 1565 in 1999; and 1286 in 2012), were studied. Height and weight were measured, BMI was computed, and WHO cut-points were used to define nutritional status. ANCOVA models were used to compare height, weight and BMI across study years; chi-square was used to determine differences in the nutritional status prevalence across the years. Results Significant differences for boys were found for height and weight (p<0.05) across the three time points, where those from 2012 were the heaviest, but those in 1999 were the tallest, and for BMI the highest value was observed in 2012 (1992<2012, 1999<2012). Among girls, those from 1999 were the tallest (1992<1999, 1999>2012), and those from 2012 had the highest BMI (1999<2012). In general, similar patterns were observed when mean values were analyzed by age. A positive trend was observed for overweight and obesity prevalences, whereas a negative trend emerged for wasting, stunting-wasting (in boys), and normal-weight (in girls); no clear trend was evident for stunting. Conclusion Significant positive changes in growth and nutritional status were observed among Mozambican youth from 1992 to 2012, which are associated with economic, social and cultural transitional processes, expressing a dual burden in this population, with reduction in malnourished youth in association with an increase in the prevalence of overweight and obesity. PMID:25473837

  12. Can bone age determination provide criteria for growth hormone treatment in adopted girls with early puberty?

    PubMed

    Proos, L A; Lönnerholm, T; Jonsson, B; Tuvemo, T

    2006-01-01

    In treatment of idiopathic central precocious puberty, GnRH analogues (GnRHa) have been accepted as the treatment of choice. Since growth velocity may be impaired with GnRHa treatment growth hormone (GH) treatment has been added in clinical trials. Recently, a study followed adopted girls with early or precocious puberty on GnRHa or combined GnRHa and GH treatment to final height. It was found that final height was significantly higher in the combined treatment group, although the difference was small. It was seen that patients that were extremely short at arrival and short at start of treatment seemed to be candidates for combined treatment. We have now analysed the data in order to define criteria for the sub-group in need of combined GnRHa-GH treatment in order to achieve normal final height, i.e. above -2 SDS. Bone ages of 46 patients at start of treatment, randomized to either GnRHa treatment or GnRHa treatment combined with GH, were examined blindly by the same radiologist and the PAH calculated. The methods according to Greulich-Pyle / Bayley-Pinneau (GP/BP) and Tanner-Whitehouse (TW2) were used. Predictions versus final height data were analysed. The accuracy of FH prediction was greatest for GnRHa treated group using the GP/BP method. The GP/BP method gave useful cut off limits for when combined treatment was necessary to possibly achieve normal height. If pre-treatment GP/PAH was > 157cm, the patients attained normal height with GnRHa treatment only. Ten out of 13 (77%) such girls could be correctly identified. Using TW2 with a cut off of 164 cm, 9 out of 13 could be selected. Using a multi regression equation of best fit the number of correctly selected cases for GnRHa treatment only, could not be further increased in this group. We conclude that bone age determination and adult height prediction with the Greulich-Pyle/Bayley-Pinneau method, provides useful criteria for selecting the subgroup of adopted girls with early puberty where combined treatment

  13. Effect of tobacco smoke exposure during pregnancy and preschool age on growth from birth to adolescence: a cohort study

    PubMed Central

    2014-01-01

    Background There is strong evidence of an association between maternal smoking during pregnancy and restriction of intrauterine growth, but the effects of this exposure on postnatal linear growth are not well defined. Furthermore, few studies have investigated the role of tobacco smoke exposure also after pregnancy on linear growth until adolescence. In this study we investigated the effect of maternal smoking exposure during pregnancy and preschool age on linear growth from birth to adolescence. Methods We evaluated a cohort of children born between 1994 and 1999 in Cuiabá, Brazil, who attended primary health clinics for vaccination between the years 1999 and 2000 (at preschool age) and followed-up after approximately ten years. Individuals were located in public and private schools throughout the country using the national school census. Height/length was measured, and length at birth was collected at maternity departments. Stature in childhood and adolescence was assessed using the height-for-age index sex-specific expressed as z-score from curves published by the World Health Organization. Linear mixed effects models were used to estimate the association between exposure to maternal smoking, during pregnancy and preschool age, and height of children assessed at birth, preschool and school age, adjusted for age of the children. Results We evaluated 2405 children in 1999–2000, length at birth was obtained from 2394 (99.5%), and 1716 at follow-up (71.4% of baseline), 50.7% of the adolescents were male. The z-score of height-for-age was lower among adolescents exposed to maternal smoking both during pregnancy and childhood (p < 0.01). Adjusting for age, sex, maternal height, maternal schooling, socioeconomic position at preschool age, and breastfeeding, children exposed to maternal smoking both during pregnancy and preschool age showed persistent lower height-for-age since birth to adolescence (coefficient: −0.32, p < 0.001) compared to non

  14. Age-specific vibrissae growth rates: a tool for determining the timing of ecologically important events in Steller sea lions

    USGS Publications Warehouse

    Rea, L.D.; Christ, A.M.; Hayden, A.B.; Stegall, V.K.; Farley, S.D.; Stricker, Craig A.; Mellish, J.E.; Maniscalco, John M.; Waite, J.N.; Burkanov, V.N.; Pitcher, K.W.

    2015-01-01

    Steller sea lions (SSL; Eumetopias jubatus) grow their vibrissae continually, providing a multiyear record suitable for ecological and physiological studies based on stable isotopes. An accurate age-specific vibrissae growth rate is essential for registering a chronology along the length of the record, and for interpreting the timing of ecologically important events. We utilized four methods to estimate the growth rate of vibrissae in fetal, rookery pup, young-of-the-year (YOY), yearling, subadult, and adult SSL. The majority of vibrissae were collected from SSL live-captured in Alaska and Russia between 2000 and 2013 (n = 1,115), however, vibrissae were also collected from six adult SSL found dead on haul-outs and rookeries during field excursions to increase the sample size of this underrepresented age group. Growth rates of vibrissae were generally slower in adult (0.44 ± 0.15 cm/mo) and subadult (0.61 ± 0.10 cm/mo) SSL than in YOY (0.87 ± 0.28 cm/mo) and fetal (0.73 ± 0.05 cm/mo) animals, but there was high individual variability in these growth rates within each age group. Some variability in vibrissae growth rates was attributed to the somatic growth rate of YOY sea lions between capture events (P = 0.014, r2 = 0.206, n = 29).

  15. Hydrocarbon distribution patterns in Nigerian growth-fault structures controlled by structural style and stratigraphy

    SciTech Connect

    Weber, K.J.

    1986-05-01

    Growth faults are considered to be major migration conduits in the Niger delta. However, the hydrocarbon distribution often shows such seemingly erratic patterns that doubt remains about the actual migration processes. After considering the sequential aspects of hydrocarbon generation and possible contemporaneous structural deformation, some of the apparent inconsistencies in the along-fault migration theory can be explained. When the authors study the relationship of fault-sealing capacity with the sand and shale thickness distribution, systematic patterns of hydrocarbon distribution are clearly revealed in many fields. The occurrence of several thick, somewhat undercompacted clay layers that locally form effective seals to vertical migration is also important. Structures with a predominance of thick sands and thin shales can trap large volumes of hydrocarbons, but only if they are unfaulted. More complex growth-fault structures, cut by secondary faults, will only be prominent oil fields if the shales are sufficiently thick to cause widespread fault sealing and shale-to-shale juxtaposition along faults. In many causes the lateral distribution of hydrocarbons over a series of fault blocks can be predicted fairly accurately on the basis of these considerations. An interesting phenomenon related to the proposed migration system is the occurrence of water trapped downdip from a hydrocarbon accumulation. Differences as large as 1000 ft can exist between the oil-water contacts on opposite flanks of a reservoir.

  16. Age-Related Changes in Body Composition of Bovine Growth Hormone Transgenic Mice

    PubMed Central

    Palmer, Amanda J.; Chung, Min-Yu; List, Edward O.; Walker, Jennifer; Okada, Shigeru; Kopchick, John J.; Berryman, Darlene E.

    2009-01-01

    GH has a significant impact on body composition due to distinct anabolic and catabolic effects on lean and fat mass, respectively. Several studies have assessed body composition in mice expressing a GH transgene. Whereas all studies report enhanced growth of transgenic mice as compared with littermate controls, there are inconsistencies in terms of the relative proportion of lean mass to fat mass in these animals. The purpose of this study was to characterize the accumulation of adipose and lean mass with age and according to gender in a bovine (b) GH transgenic mouse line. Weight and body composition measurements were assessed in male and female bGH mice with corresponding littermate controls in the C57BL/6J genetic background. Body composition measurements began at 6 wk and continued through 1 yr of age. At the conclusion of the study, tissue weights were determined and triglyceride content was quantified in liver and kidney. Although body weights for bGH mice were significantly greater than their corresponding littermate controls at all time points, body composition measurements revealed an unexpected transition midway through analyses. That is, younger bGH mice had relatively more fat mass than nontransgenic littermates, whereas bGH mice became significantly leaner than controls by 4 months in males and 6 months in females. These results reveal the importance in timing and gender when conducting studies related to body composition or lean and fat tissue in GH transgenic mice or in other genetically manipulated mouse strains in which body composition may be impacted. PMID:18948397

  17. 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

  18. Periods of child growth up to age 8 years in Ethiopia, India, Peru and Vietnam: key distal household and community factors.

    PubMed

    Schott, Whitney B; Crookston, Benjamin T; Lundeen, Elizabeth A; Stein, Aryeh D; Behrman, Jere R

    2013-11-01

    Recent research has demonstrated some growth recovery among children stunted in infancy. Less is known about key age ranges for such growth recovery, and what factors are correlates with this growth. This study characterized child growth up to age 1 year, and from ages 1 to 5 and 5 to 8 years controlling for initial height-for-age z-score (HAZ), and identified key distal household and community factors associated with these growth measures using longitudinal data on 7266 children in the Young Lives (YL) study in Ethiopia, India, Peru and Vietnam. HAZ at about age 1 year and age in months predicted much of the variation in HAZ at age 5 years, but 40-71% was not predicted. Similarly, HAZ at age 5 years and age in months did not predict 26-47% of variation in HAZ at 8 years. Multiple regression analysis suggests that parental schooling, consumption, and mothers' height are key correlates of HAZ at about age 1 and also are associated with unpredicted change in HAZ from ages 1 to 5 and 5 to 8 years, given initial HAZ. These results underline the importance of a child's starting point in infancy in determining his or her growth, point to key distal household and community factors that may determine early growth in early life and subsequent growth recovery and growth failure, and indicate that these factors vary some by country, urban/rural designation, and child sex.

  19. Pharmacokinetics and acute lipolytic actions of growth hormone. Impact of age, body composition, binding proteins, and other hormones.

    PubMed

    Hansen, Troels Krarup

    2002-10-01

    The biologic actions of endogeneous growth hormone (GH) depend on its secretion and clearance rates as well as sensitivity at the receptor level. Aberrations in GH pharmacokinetics and pharmacodynamics may occur with increasing age, and have been implicated in diseases such as obesity, diabetes mellitus, and critical illness. In this review, recent insights into the association between GH metabolism and age, body composition, binding proteins and other hormones are discussed.

  20. Aging and perceived event structure as a function of modality.

    PubMed

    Magliano, Joseph; Kopp, Kristopher; McNerney, M Windy; Radvansky, Gabriel A; Zacks, Jeffrey M

    2012-01-01

    The majority of research on situation model processing in older adults has focused on narrative texts. Much of this research has shown that many important aspects of constructing a situation model for a text are preserved and may even improve with age. However, narratives need not be text-based, and little is known as to whether these findings generalize to visually-based narratives. The present study assessed the impact of story modality on event segmentation, which is a basic component of event comprehension. Older and younger adults viewed picture stories or read text versions of them and segmented them into events. There was comparable alignment between the segmentation judgments and a theoretically guided analysis of shifts in situational features across modalities for both populations. These results suggest that situation models provide older adults with a stable basis for event comprehension across different modalities of expereinces.

  1. Aging and perceived event structure as a function of modality

    PubMed Central

    Magliano, Joseph; Kopp, Kristopher; McNerney, M. Windy; Radvansky, Gabriel A.; Zacks, Jeffrey M.

    2012-01-01

    The majority of research on situation model processing in older adults has focused on narrative texts. Much of this research has shown that many important aspects of constructing a situation model for a text are preserved and may even improve with age. However, narratives need not be text-based, and little is known as to whether these findings generalize to visually-based narratives. The present study assessed the impact of story modality on event segmentation, which is a basic component of event comprehension. Older and younger adults viewed picture stories or read text versions of them and segmented them into events. There was comparable alignment between the segmentation judgments and a theoretically guided analysis of shifts in situational features across modalities for both populations. These results suggest that situation models provide older adults with a stable basis for event comprehension across different modalities of expereinces. PMID:22182344

  2. Growth hormone action predicts age-related white adipose tissue dysfunction and senescent cell burden in mice.

    PubMed

    Stout, Michael B; Tchkonia, Tamara; Pirtskhalava, Tamar; Palmer, Allyson K; List, Edward O; Berryman, Darlene E; Lubbers, Ellen R; Escande, Carlos; Spong, Adam; Masternak, Michal M; Oberg, Ann L; LeBrasseur, Nathan K; Miller, Richard A; Kopchick, John J; Bartke, Andrzej; Kirkland, James L

    2014-07-01

    The aging process is associated with the development of several chronic diseases. White adipose tissue (WAT) may play a central role in age-related disease onset and progression due to declines in adipogenesis with advancing age. Recent reports indicate that the accumulation of senescent progenitor cells may be involved in age-related WAT dysfunction. Growth hormone (GH) action has profound effects on adiposity and metabolism and is known to influence lifespan. In the present study we tested the hypothesis that GH activity would predict age-related WAT dysfunction and accumulation of senescent cells. We found that long-lived GH-deficient and -resistant mice have reduced age-related lipid redistribution. Primary preadipocytes from GH-resistant mice also were found to have greater differentiation capacity at 20 months of age when compared to controls. GH activity was also found to be positively associated with senescent cell accumulation in WAT. Our results demonstrate an association between GH activity, age-related WAT dysfunction, and WAT senescent cell accumulation in mice. Further studies are needed to determine if GH is directly inducing cellular senescence in WAT or if GH actions on other target organs or alternative downstream alterations in insulin-like growth factor-1, insulin or glucose levels are responsible.

  3. Growth hormone action predicts age-related white adipose tissue dysfunction and senescent cell burden in mice

    PubMed Central

    Pirtskhalava, Tamar; Palmer, Allyson K.; List, Edward O.; Berryman, Darlene E.; Lubbers, Ellen R.; Escande, Carlos; Spong, Adam; Masternak, Michal M.; Oberg, Ann L.; LeBrasseur, Nathan K.; Miller, Richard A.; Kopchick, John J.; Bartke, Andrzej; Kirkland, James L.

    2014-01-01

    The aging process is associated with the development of several chronic diseases. White adipose tissue (WAT) may play a central role in age-related disease onset and progression due to declines in adipogenesis with advancing age. Recent reports indicate that the accumulation of senescent progenitor cells may be involved in age-related WAT dysfunction. Growth hormone (GH) action has profound effects on adiposity and metabolism and is known to influence lifespan. In the present study we tested the hypothesis that GH activity would predict age-related WAT dysfunction and accumulation of senescent cells. We found that long-lived GH-deficient and -resistant mice have reduced age-related lipid redistribution. Primary preadipocytes from GH-resistant mice also were found to have greater differentiation capacity at 20 months of age when compared to controls. GH activity was also found to be positively associated with senescent cell accumulation in WAT. Our results demonstrate an association between GH activity, age-related WAT dysfunction, and WAT senescent cell accumulation in mice. Further studies are needed to determine if GH is directly inducing cellular senescence in WAT or if GH actions on other target organs or alternative downstream alterations in insulin-like growth factor-1, insulin or glucose levels are responsible. PMID:25063774

  4. Postnatal growth in term infants born small for gestational age is associated with later neurocognitive and metabolic outcomes.

    PubMed

    Castanys-Muñoz, Esther; Kennedy, Kathy; Castañeda-Gutiérrez, Eurídice; Forsyth, Stewart; Godfrey, Keith M; Koletzko, Berthold; Ozanne, Susan E; Rueda, Ricardo; Schoemaker, Marieke; van der Beek, Eline M; van Buuren, Stef; Ong, Ken K

    2017-04-06

    We systematically reviewed papers published in English between 1994 and October 2015 on how postnatal weight gain and growth affects neurodevelopment and metabolic outcomes in term-born small for gestational age (SGA) infants. Two randomised trials reported that enriched infant formulas that promoted early growth also increased fat mass, lean mass and blood pressure, but had no effect on early neurocognitive outcomes. Meanwhile, 31 observational studies reported consistent positive associations between postnatal weight gain and growth with neurocognitive outcomes, adiposity, insulin resistance and blood pressure.

  5. 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.

  6. Interplay between Shear Loading and Structural Aging in a Physical Gelatin Gel

    SciTech Connect

    Ronsin, O.; Caroli, C.; Baumberger, T.

    2009-09-25

    We show that the aging of the mechanical relaxation of a gelatin gel exhibits the same scaling phenomenology as polymer and colloidal glasses. In addition, gelatin is known to exhibit logarithmic structural aging (stiffening). We find that stress accelerates this process. However, this effect is definitely irreducible to a mere age shift with respect to natural aging. We suggest that it is interpretable in terms of elastically aided elementary (coil->helix) local events whose dynamics gradually slows down as aging increases geometric frustration.

  7. Depressing effect of 0.1 wt.% Cr addition into Sn-9Zn solder alloy on the intermetallic growth with Cu substrate during isothermal aging

    SciTech Connect

    Hu Jin; Hu Anmin; Li Ming; Mao Dali

    2010-03-15

    In this paper, the effect of 0.1 wt.% Cr addition into Sn-9Zn lead-free solder alloys on the growth of intermetallic compound (IMC) with Cu substrate during soldering and subsequent isothermal aging was investigated. During soldering, it was found that 0.1 wt.% Cr addition did not contribute to forming the IMC, which was verified as the same phase structure as the IMC for Sn-9Zn/Cu. However, during solid-state isothermal aging, the IMC growth was remarkably depressed by 0.1 wt.% Cr addition in the Sn-9Zn solder, and this effect tended to be more prominent at higher aging temperature. The activation energy for IMC growth was determined as 21.2 kJ mol{sup -1} and 42.9 kJ mol{sup -1} for Sn-9Zn/Cu and Sn-9Zn-Cr/Cu, respectively. The reduced diffusion coefficient was confirmed for the 0.1Cr-containing solder/Cu. Energy-dispersive X-ray mapping and point analysis also showed ZnCr phase existing in solder matrix, which can reduce diffusion rate of Zn atoms.

  8. Geroprotectors.org: a new, structured and curated database of current therapeutic interventions in aging and age-related disease.

    PubMed

    Moskalev, Alexey; Chernyagina, Elizaveta; de Magalhães, João Pedro; Barardo, Diogo; Thoppil, Harikrishnan; Shaposhnikov, Mikhail; Budovsky, Arie; Fraifeld, Vadim E; Garazha, Andrew; Tsvetkov, Vasily; Bronovitsky, Evgeny; Bogomolov, Vladislav; Scerbacov, Alexei; Kuryan, Oleg; Gurinovich, Roman; Jellen, Leslie C; Kennedy, Brian; Mamoshina, Polina; Dobrovolskaya, Evgeniya; Aliper, Alex; Kaminsky, Dmitry; Zhavoronkov, Alex

    2015-09-01

    As the level of interest in aging research increases, there is a growing number of geroprotectors, or therapeutic interventions that aim to extend the healthy lifespan and repair or reduce aging-related damage in model organisms and, eventually, in humans. There is a clear need for a manually-curated database of geroprotectors to compile and index their effects on aging and age-related diseases and link these effects to relevant studies and multiple biochemical and drug databases. Here, we introduce the first such resource, Geroprotectors (http://geroprotectors.org). Geroprotectors is a public, rapidly explorable database that catalogs over 250 experiments involving over 200 known or candidate geroprotectors that extend lifespan in model organisms. Each compound has a comprehensive profile complete with biochemistry, mechanisms, and lifespan effects in various model organisms, along with information ranging from chemical structure, side effects, and toxicity to FDA drug status. These are presented in a visually intuitive, efficient framework fit for casual browsing or in-depth research alike. Data are linked to the source studies or databases, providing quick and convenient access to original data. The Geroprotectors database facilitates cross-study, cross-organism, and cross-discipline analysis and saves countless hours of inefficient literature and web searching. Geroprotectors is a one-stop, knowledge-sharing, time-saving resource for researchers seeking healthy aging solutions.

  9. Growth differentiation factor 11 (GDF11) - a promising anti-ageing factor - is highly concentrated in platelets.

    PubMed

    Bueno, J L; Ynigo, M; de Miguel, C; Gonzalo-Daganzo, R M; Richart, A; Vilches, C; Regidor, C; García-Marco, J A; Flores-Ballester, E; Cabrera, J R

    2016-11-01

    Recent research suggests that growth differentiation factor 11 (GDF11) could reverse age-related diseases and that its blood concentration decreases with age. This poses plasma from young donors as a therapeutic GDF11 source to treat age-related diseases. In addition, the tissue source of circulating GDF11 remains unknown. We analysed GDF11 levels in paired samples of serum, plasma and platelet lysate (PL) from 23 volunteers. Plasma and PL were collected by plateletpheresis. Here, we show that GDF11 is highly concentrated in platelets and that the circulating levels reported in previous studies could be biased as a result of serum sample manipulation.

  10. Age structure, carbonate production and shell loss rate in an Early Miocene reef of the giant oyster Crassostrea gryphoides

    NASA Astrophysics Data System (ADS)

    Harzhauser, Mathias; Djuricic, Ana; Mandic, Oleg; Neubauer, Thomas A.; Zuschin, Martin; Pfeifer, Norbert

    2016-02-01

    We present the first analysis of population structure and cohort distribution in a fossil oyster shell bed based on 1121 shells of the giant oyster Crassostrea gryphoides (von Schlotheim, 1813). Data derive from terrestrial laser scanning of a Lower Miocene shell bed covering 459 m2. Within two transects, individual shells were manually outlined on a digital surface model and cross-checked based on high-resolution orthophotos, resulting in accurate information on center line length and area of exposed shell surface. A growth model was calculated, revealing this species as the fastest growing and largest Crassostrea known so far. Non-normal distribution of size, area and age data hints at the presence of at least four distinct recruitment cohorts. The rapid decline of frequency amplitudes with age is interpreted to be a function of mortality and shell loss. The calculated shell half-lives range around a few years, indicating that oyster reefs were geologically short-lived structures, which could have been fully degraded on a decadal scale. Crassostrea gryphoides reefs were widespread and common along the Miocene circum-Tethyan coasts. Given its enormous growth performance of ˜ 150 g carbonate per year this species has been an important carbonate producer in estuarine settings. Yet, the rapid shell loss impeded the formation of stable structures comparable to coral reefs.

  11. Age structure, carbonate production and shell loss rate in an Early Miocene reef of the giant oyster Crassostrea gryphoides

    NASA Astrophysics Data System (ADS)

    Harzhauser, M.; Djuricic, A.; Mandic, O.; Neubauer, T. A.; Zuschin, M.; Pfeifer, N.

    2015-09-01

    We present the first analysis of population structure and cohort distribution in a fossil oyster reef based on more than 1121 shells of the giant oyster Crassostrea gryphoides (Schlotheim, 1813). Data derive from Terrestrial Laser Scanning of a Lower Miocene shell bed covering 459 m2. Within two transects, individual shells were manually outlined on a digital surface model and cross-checked based on high-resolution orthophotos, resulting in accurate information on center line length and area of exposed shell surface. A growth model was calculated, revealing this species as the fastest growing and largest Crassostrea known so far. Non-normal distribution of size, area and age data hints at the presence of at least four distinct recruitment cohorts. The rapid decline of frequency amplitudes with age is interpreted to be a function of mortality and shell loss. The calculated shell half-lives range around few years, indicating that oyster reefs were geologically short-lived structures, which could have been fully degraded on a decadal scale. Crassostrea gryphoides reefs were widespread and common along the Miocene circum-Tethyan coasts. Given its enormous growth performance of ~ 150 g carbonate per year this species has been an important carbonate producer in estuarine settings. Yet, the rapid shell loss impeded the formation of stable structures comparable to coral reefs.

  12. Maintenance of muscle mass and load-induced growth in Muscle RING Finger 1 null mice with age.

    PubMed

    Hwee, Darren T; Baehr, Leslie M; Philp, Andrew; Baar, Keith; Bodine, Sue C

    2014-02-01

    Age-related loss of muscle mass occurs to varying degrees in all individuals and has a detrimental effect on morbidity and mortality. Muscle RING Finger 1 (MuRF1), a muscle-specific E3 ubiquitin ligase, is believed to mediate muscle atrophy through the ubiquitin proteasome system (UPS). Deletion of MuRF1 (KO) in mice attenuates the loss of muscle mass following denervation, disuse, and glucocorticoid treatment; however, its role in age-related muscle loss is unknown. In this study, skeletal muscle from male wild-type (WT) and MuRF1 KO mice was studied up to the age of 24 months. Muscle mass and fiber cross-sectional area decreased significantly with age in WT, but not in KO mice. In aged WT muscle, significant decreases in proteasome activities, especially 20S and 26S β5 (20-40% decrease), were measured and were associated with significant increases in the maladaptive endoplasmic reticulum (ER) stress marker, CHOP. Conversely, in aged MuRF1 KO mice, 20S or 26S β5 proteasome activity was maintained or decreased to a lesser extent than in WT mice, and no increase in CHOP expression was measured. Examination of the growth response of older (18 months) mice to functional overload revealed that old WT mice had significantly less growth relative to young mice (1.37- vs. 1.83-fold), whereas old MuRF1 KO mice had a normal growth response (1.74- vs. 1.90-fold). These data collectively suggest that with age, MuRF1 plays an important role in the control of skeletal muscle mass and growth capacity through the regulation of cellular stress.

  13. A structure-based extracellular matrix expansion mechanism of fibrous tissue growth.

    PubMed

    Kalson, Nicholas S; Lu, Yinhui; Taylor, Susan H; Starborg, Tobias; Holmes, David F; Kadler, Karl E

    2015-05-20

    Embryonic growth occurs predominately by an increase in cell number; little is known about growth mechanisms later in development when fibrous tissues account for the bulk of adult vertebrate mass. We present a model for fibrous tissue growth based on 3D-electron microscopy of mouse tendon. We show that the number of collagen fibrils increases during embryonic development and then remains constant during postnatal growth. Embryonic growth was explained predominately by increases in fibril number and length. Postnatal growth arose predominately from increases in fibril length and diameter. A helical crimp structure was established in embryogenesis, and persisted postnatally. The data support a model where the shape and size of tendon is determined by the number and position of embryonic fibroblasts. The collagen fibrils that these cells synthesise provide a template for postnatal growth by structure-based matrix expansion. The model has important implications for growth of other fibrous tissues and fibrosis.

  14. Effect of recombinant human growth hormone on age-related hepatocyte changes in old male and female Wistar rats.

    PubMed

    Castillo, Carmen; Salazar, Veronica; Ariznavarreta, Carmen; Vara, Elena; Tresguerres, Jesus A F

    2004-10-01

    Aging induces changes in several organs, such as the liver, and this process might be due to damage caused by free radicals and inflammatory mediators. The growth hormone (GH)/insulin-like growth factor-1 (IGF-1) axis shows a reduction with age, and this fact could be associated with some age-related changes. The aim of this study was to investigate the effect of GH administration on age-induced alterations in hepatocytes. Two and twenty two month-old male and female Wistar rats were used. Old rats were treated with human recombinant GH for 10 wk. At the end of the treatment, hepatocytes were isolated from the liver and cultured, and different parameters were measured in cells and medium. Plasma IGF-1 was also measured. Aging significantly decreased plasma IGF-1 in males. In females, plasma IGF-1 was also reduced, but not significantly. GH treatment restored plasma IGF-1 levels to values similar to young males. Aging was associated with a significant increase in lipid peroxidation (LPO), nitric oxide (NO), carbon monoxide (CO) and cyclic guanosyl-monophosphate (cGMP), as well as a reduction in adenosyl triphosphate (ATP) and phosphatidylcholine (PC) synthesis. GH administration partially prevented all these changes in males. In females, some of the parameters were significantly improved by GH (ATP, CO, cGMP), while others showed a tendency to improvement, although differences did not reach significance. In conclusion, GH administration could exert beneficial effects against age-related changes in hepatocytes, mainly in males.

  15. Role of physical activity and sleep duration in growth and body composition of preschool-aged children

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The impact of physical activity patterns and sleep duration on growth and body composition of preschool-aged children remains unresolved. Aims were (1) to delineate cross-sectional associations among physical activity components, sleep, total energy expenditure (TEE), and body size and composition; ...

  16. 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.

  17. The Not-so-Dark Ages: ecology for human growth in medieval and early twentieth century Portugal as inferred from skeletal growth profiles.

    PubMed

    Cardoso, Hugo F V; Garcia, Susana

    2009-02-01

    This study attempts to address the issue of relative living standards in Portuguese medieval and early 20th century periods. Since the growth of children provides a good measure of environmental quality for the overall population, the skeletal growth profiles of medieval Leiria and early 20th century Lisbon were compared. Results show that growth in femur length of medieval children did not differ significantly from that of early 20th century children, but after puberty medieval adolescents seem to have recovered, as they have significantly longer femora as adults. This is suggestive of greater potential for catch-up growth in medieval adolescents. We suggest that this results from distinct child labor practices, which impact differentially on the growth of Leiria and Lisbon adolescents. Work for medieval children and adolescents were related to family activities, and care and attention were provided by family members. Conversely, in early 20th century Lisbon children were more often sent to factories at around 12 years of age as an extra source of family income, where they were exploited for their labor. Since medieval and early 20th century children were stunted at an early age, greater potential for catch-up growth in medieval adolescents results from exhausting work being added to modern adolescent's burdens of disease and poor diet, when they entered the labor market. Although early 20th century Lisbon did not differ in overall unfavorable living conditions from medieval Leiria, after puberty different child labor practices may have placed modern adolescents at greater risk of undernutrition and poor growth.

  18. The aging of elite male athletes: age-related changes in performance and skeletal muscle structure and function

    PubMed Central

    Faulkner, John A.; Davis, Carol S.; Mendias, Christopher L.; Brooks, Susan V.

    2009-01-01

    Objective The paper addresses the degree to which the attainment of the status as an elite athlete in different sports ameliorates the known age-related losses in skeletal muscle structure and function. Design The retrospective design, based on comparisons of published data on former elite and masters athletes and data on control subjects, assessed the degree to which the attainment of ‘elite and masters athlete status’ ameliorated the known age-related changes in skeletal muscle structure and function. Setting Institutional. Participants Elite male athletes. Interventions Participation in selected individual and team sports. Main Outcome Measurements Strength, power, VO2 max and performance. Results For elite athletes in all sports, as for the general population, age-related muscle atrophy begins at about 50 years of age. Despite the loss of muscle mass, elite athletes who maintain an active life style age gracefully with few health problems. Conversely, those who lapse into inactivity regress toward general population norms for fitness, weight control, and health problems. Elite athletes in the dual and team sports have careers that rarely extend into the thirties. Conclusions Life long physical activity does not appear to have any impact on the loss in fiber number. The loss of fibers can be buffered to some degree by hypertrophy of fibers that remain. Surprisingly, the performance of elite athletes in all sports appears to be impaired before the onset of the fiber loss. Even with major losses in physical capacity and muscle mass, the performance of elite and masters athletes is remarkable. PMID:19001883

  19. Effect of nano-TiO(2) on strength of naturally aged seeds and growth of spinach.

    PubMed

    Zheng, Lei; Hong, Fashui; Lu, Shipeng; Liu, Chao

    2005-04-01

    The effects of nano-TiO(2) (rutile) and non-nano-TiO(2) on the germination and growth of naturally aged spinach seeds were studied by measuring the germination rate and the germination and vigor indexes of aged spinach seeds. An increase of these factors was observed at 0.25-4% nano-TiO(2) treatment. During the growth stage, the plant dry weight was increased, as was the chlorophyll formation, the ribulosebisphosphate carboxylase/oxygenase activity, and the photosynthetic rate. The best results were found at 2.5% nano-TiO(2). The effects of non-nano-TiO(2) are not significant. It is shown that the physiological effects are related to the nanometer-size particles, but the mechanism by which nano-TiO(2) improves the growth of spinach seeds still needs further study.

  20. Association of structural global brain network properties with intelligence in normal aging.

    PubMed

    Fischer, Florian U; Wolf, Dominik; Scheurich, Armin; Fellgiebel, Andreas

    2014-01-01

    Higher general intelligence attenuates age-associated cognitive decline and the risk of dementia. Thus, intelligence has been associated with cognitive reserve or resilience in normal aging. Neurophysiologically, intelligence is considered as a complex capacity that is dependent on a global cognitive network rather than isolated brain areas. An association of structural as well as functional brain network characteristics with intelligence has already been reported in young adults. We investigated the relationship between global structural brain network properties, general intelligence and age in a group of 43 cognitively healthy elderly, age 60-85 years. Individuals were assessed cross-sectionally using Wechsler Adult Intelligence Scale-Revised (WAIS-R) and diffusion-tensor imaging. Structural brain networks were reconstructed individually using deterministic tractography, global network properties (global efficiency, mean shortest path length, and clustering coefficient) were determined by graph theory and correlated to intelligence scores within both age groups. Network properties were significantly correlated to age, whereas no significant correlation to WAIS-R was observed. However, in a subgroup of 15 individuals aged 75 and above, the network properties were significantly correlated to WAIS-R. Our findings suggest that general intelligence and global properties of structural brain networks may not be generally associated in cognitively healthy elderly. However, we provide first evidence of an association between global structural brain network properties and general intelligence in advanced elderly. Intelligence might be affected by age-associated network deterioration only if a certain threshold of structural degeneration is exceeded. Thus, age-associated brain structural changes seem to be partially compensated by the network and the range of this compensation might be a surrogate of cognitive reserve or brain resilience.

  1. Growth of the dolphinfish Coryphaena hippurus from north-eastern Brazil with an appraisal of the efficacy of scales and otoliths for ageing.

    PubMed

    Lessa, R; Santana, F M

    2016-07-01

    Age and growth of the dolphinfish Coryphaena hippurus caught off north-eastern Brazil were studied by counting growth increments on scales and otoliths. A sample (n = 2338) measuring 7·7-195 cm fork length (LF ) was collected from September 2001 to February 2003. The scales (n = 69) removed from six different regions of the body were examined and those from the caudal region exhibited greater morphological regularity, symmetry and a smaller rate of regeneration. The regression between caudal scale radius (RS ) and LF displayed was linear (LF  = 28·334 RS  + 9·186; r(2)  = 0·754). Otolith micro-increments were counted assuming daily periodicity. Ages estimated from otoliths ranged from 64 to 659 days. The von Bertalanffy growth model was fitted based on the otolith readings generating L∞  = 194·1 cm LF , k = 0·912 year(-1) and t0  = 0·081 years. Species longevity was estimated to be c. 4 years. Ninety-eight per cent of the overall sample was adult specimens well above the age of first maturity in the study area. The large variability between scale length and LF and the failure to ascertain increment deposition periodicity suggest that scales are not appropriate for ageing C. hippurus and analysis of otolith micro-increments is deemed the best structure for ageing this species in the study area.

  2. Structural evidence that human acetylcholinesterase inhibited by tabun ages through O-dealkylation.

    PubMed

    Carletti, Eugénie; Colletier, Jacques-Philippe; Dupeux, Florine; Trovaslet, Marie; Masson, Patrick; Nachon, Florian

    2010-05-27

    Tabun is a warfare agent that inhibits human acetylcholinesterase (hAChE) by rapid phosphylation of the catalytic serine. A time-dependent reaction occurs on the tabun adduct, leading to an "aged" enzyme, resistant to oxime reactivators. The aging reaction may proceed via either dealkylation or deamidation, depending on the stereochemistry of the phosphoramidyl adduct. We solved the X-ray structure of aged tabun-hAChE complexed with fasciculin II, and we show that aging proceeds through O-dealkylation, in agreement with the aging mechanism that we determined for tabun-inhibited human butyrylcholinesterase and mouse acetylcholinesterase. Noteworthy, aging and binding of fasciculin II lead to an improved thermostability, resulting from additional stabilizing interactions between the two subdomains that face each other across the active site gorge. This first structure of hAChE inhibited by a nerve agent provides structural insight into the inhibition and aging mechanisms and a structural template for the design of molecules capable of reactivating aged hAChE.

  3. Estimating survival rates with time series of standing age-structure data

    USGS Publications Warehouse

    Udevitz, Mark S.; Gogan, Peter J.

    2014-01-01

    It has long been recognized that age-structure data contain useful information for assessing the status and dynamics of wildlife populations. For example, age-specific survival rates can be estimated with just a single sample from the age distribution of a stable, stationary population. For a population that is not stable, age-specific survival rates can be estimated using techniques such as inverse methods that combine time series of age-structure data with other demographic data. However, estimation of survival rates using these methods typically requires numerical optimization, a relatively long time series of data, and smoothing or other constraints to provide useful estimates. We developed general models for possibly unstable populations that combine time series of age-structure data with other demographic data to provide explicit maximum likelihood estimators of age-specific survival rates with as few as two years of data. As an example, we applied these methods to estimate survival rates for female bison (Bison bison) in Yellowstone National Park, USA. This approach provides a simple tool for monitoring survival rates based on age-structure data.

  4. Factor Structure of Attention Deficit Hyperactivity Disorder Symptoms for Children Age 3 to 5 Years

    ERIC Educational Resources Information Center

    McGoey, Kara E.; Schreiber, James; Venesky, Lindsey; Westwood, Wendy; McGuirk, Lindsay; Schaffner, Kristen

    2015-01-01

    The diagnosis of attention deficit hyperactivity disorder (ADHD) distinguishes two dimensions of symptoms, inattention and hyperactivity-impulsivity for ages 3 to adulthood. Currently, no separate classification for preschool-age children exists, whereas preliminary research suggests that the two-factor structure of ADHD may not match the…

  5. Aging Optimization of Aluminum-Lithium Alloy C458 for Application to Cryotank Structures

    NASA Technical Reports Server (NTRS)

    Sova, B. J.; Sankaran, K. K.; Babel, H. W.; Farahmand, B.; Rioja, R.

    2003-01-01

    This viewgraph report presents an examination of the fracture toughness of aluminum-lithium alloy C458 for use in cryotank structures. Topics cover include: cryogenics, alloy composition, strengthing precipitates in C458, cryogenic fracture toughness improvements, design of experiments for measuring aging optimization of C458 plate and effects of aging of properties of C458 plate.

  6. Structural hippocampal network alterations during healthy aging: a multi-modal MRI study

    PubMed Central

    Pelletier, Amandine; Periot, Olivier; Dilharreguy, Bixente; Hiba, Bassem; Bordessoules, Martine; Pérès, Karine; Amieva, Hélène; Dartigues, Jean-François; Allard, Michèle; Catheline, Gwénaëlle

    2013-01-01

    While hippocampal atrophy has been described during healthy aging, few studies have examined its relationship with the integrity of White Matter (WM) connecting tracts of the limbic system. This investigation examined WM structural damage specifically related to hippocampal atrophy in healthy aging subjects (n = 129), using morphological MRI to assess hippocampal volume and Diffusion Tensor Imaging (DTI) to assess WM integrity. Subjects with Mild Cognitive Impairment (MCI) or dementia were excluded from the analysis. In our sample, increasing age was significantly associated with reduced hippocampal volume and reduced Fractional Anisotropy (FA) at the level of the fornix and the cingulum bundle. The findings also demonstrate that hippocampal atrophy was specifically associated with reduced FA of the fornix bundle, but it was not related to alteration of the cingulum bundle. Our results indicate that the relationship between hippocampal atrophy and fornix FA values is not due to an independent effect of age on both structures. A recursive regression procedure was applied to evaluate sequential relationships between the alterations of these two brain structures. When both hippocampal atrophy and fornix FA values were included in the same model to predict age, fornix FA values remained significant whereas hippocampal atrophy was no longer significantly associated with age. According to this latter finding, hippocampal atrophy in healthy aging could be mediated by a loss of fornix connections. Structural alterations of this part of the limbic system, which have been associated with neurodegeneration in Alzheimer's disease, result at least in part from the aging process. PMID:24367331

  7. Genetic, environmental and phenotypic relationships among gestation length, birth weight, growth traits and age at first calving in beef cattle.

    PubMed

    Bourdon, R M; Brinks, J S

    1982-09-01

    Data on the Red Angus, Angus and Hereford herds of Pioneer Hi-Bred International, Inc., Des Moines, Iowa, collected from 1968 to 1976, were analyzed for relationships among gestation length, birth weight, prenatal gain (birth weight adjusted for gestation length), growth traits and age at first calving. A total of 5,691 calf records, 1,783 listing gestation length, were included in the study. Paternal half-sib analyses and least-squares procedures were used to compute heritability estimates and genetic, environmental and phenotypic correlations among traits. Genetic correlations among growth traits, including prenatal gain, were high in all cases. Heritability estimates for gestation length and birth weight were .36 and .43, respectively, for bull calves and .37 and .35 for heifer calves. Genetic correlations between these traits were .25 and .22 for bull and heifer calves, respectively. Gestation length was negatively correlated (genetically) with all growth traits except birth weight. This result suggests that faster growing fetuses may trigger parturition earlier than average. Age at first calving was negatively correlated (genetically) with growth traits, indicating a favorable relationship between growth and early reproduction. Analysis of several selection indexes combining either birth weight and yearling weight or gestation length and yearling weight indicated that continued response to selection for growth without excessive increase in birth weight is feasible. Selection for growth and moderate birth weight would be more effective than selection for growth and shorter gestation, suggesting that the former method would both shorten gestation and alter the growth curve. Repeatability estimates for gestation length and birth weight were .20 and .22, respectively. Maternal effects accounted for approximately 10% of the variation in each trait.

  8. Growth, defect structure, and THz application of stoichiometric lithium niobate

    NASA Astrophysics Data System (ADS)

    Lengyel, K.; Péter, Á.; Kovács, L.; Corradi, G.; Pálfalvi, L.; Hebling, J.; Unferdorben, M.; Dravecz, G.; Hajdara, I.; Szaller, Zs.; Polgár, K.

    2015-12-01

    Owing to the extraordinary richness of its physical properties, congruent lithium niobate has attracted multidecade-long interest both for fundamental science and applications. The combination of ferro-, pyro-, and piezoelectric properties with large electro-optic, acousto-optic, and photoelastic coefficients as well as the strong photorefractive and photovoltaic effects offers a great potential for applications in modern optics. To provide powerful optical components in high energy laser applications, tailoring of key material parameters, especially stoichiometry, is required. This paper reviews the state of the art of growing large stoichiometric LiNbO3 (sLN) crystals, in particular, the defect engineering of pure and doped sLN with emphasis on optical damage resistant (ODR) dopants (e.g., Mg, Zn, In, Sc, Hf, Zr, Sn). The discussion is focused on crystals grown by the high temperature top seeded solution growth (HTTSSG) technique using alkali oxide fluxing agents. Based on high-temperature phase equilibria studies of the Li2O-Nb2O5-X2O ternary systems (X = Na, K, Rb, Cs), the impact of alkali homologue additives on the stoichiometry of the lithium niobate phase will be analyzed, together with a summary of the ultraviolet, infrared, and far-infrared absorption spectroscopic methods developed to characterize the composition of the crystals. It will be shown that using HTTSSG from K2O containing flux, crystals closest to the stoichiometric composition can be grown characterized by a UV-edge position of at about 302 nm and a single narrow hydroxyl band in the IR with a linewidth of less than 3 cm-1 at 300 K. The threshold concentrations for ODR dopants depend on crystal stoichiometry and the valence of the dopants; Raman spectra, hydroxyl vibration spectra, and Z-scan measurements prove to be useful to distinguish crystals below and above the photorefractive threshold. Crystals just above the threshold are preferred for most nonlinear optical applications apart

  9. Structural characterization of glycosaminoglycans from zebrafish in different ages

    PubMed Central

    Zhang, Fuming; Zhang, Zhenqing; Thistle, Robert; McKeen, Lindsey; Hosoyama, Saori; Toida, Toshihiko

    2009-01-01

    The zebrafish (Danio rerio) is a popular model organism for the study of developmental biology, disease mechanisms, and drug discovery. Glycosaminoglycans (GAGs), located on animal cell membranes and in the extracellular matrix, are important molecules in cellular communication during development, in normal physiology and pathophysiology. Vertebrates commonly contain a variety of GAGs including chondroitin/dermatan sulfates, heparin/heparan sulfate, hyaluronan and keratan sulfate. Zebrafish might represent an excellent experimental organism to study the biological roles of GAGs. A recent study showing the absence of heparan sulfate in adult zebrafish, suggested a more detailed evaluation of the GAGs present in this important model organism needed to be undertaken. This report aimed at examining the structural alterations of different GAGs at the molecular level at different developmental stages. GAGs were isolated and purified from zebrafish in different stages in development ranging from 0.5 days to adult. The content and disaccharide composition of chondroitin sulfate and heparan sulfate were determined using chemical assays, liquid chromotography and mass spectrometry. The presence of HS in adult fish was also confirmed using 1H-NMR. PMID:18777207

  10. Does white matter structure or hippocampal volume mediate associations between cortisol and cognitive ageing?

    PubMed

    Cox, Simon R; MacPherson, Sarah E; Ferguson, Karen J; Royle, Natalie A; Maniega, Susana Muñoz; Hernández, Maria Del C Valdés; Bastin, Mark E; MacLullich, Alasdair M J; Wardlaw, Joanna M; Deary, Ian J

    2015-12-01

    Elevated glucocorticoid (GC) levels putatively damage specific brain regions, which in turn may accelerate cognitive ageing. However, many studies are cross-sectional or have relatively short follow-up periods, making it difficult to relate GCs directly to changes in cognitive ability with increasing age. Moreover, studies combining endocrine, MRI and cognitive variables are scarce, measurement methods vary considerably, and formal tests of the underlying causal hypothesis (cortisol→brain→cognition) are absent. In this study, 90 men, aged 73 years, provided measures of fluid intelligence, processing speed and memory, diurnal and reactive salivary cortisol and two measures of white matter (WM) structure (WM hyperintensity volume from structural MRI and mean diffusivity averaged across 12 major tracts from diffusion tensor MRI), hippocampal volume, and also cognitive ability at age 11. We tested whether negative relationships between cognitive ageing differences (over more than 60 years) and salivary cortisol were significantly mediated by WM and hippocampal volume. Significant associations between reactive cortisol at 73 and cognitive ageing differences between 11 and 73 (r=-.28 to -.36, p<.05) were partially mediated by both WM structural measures, but not hippocampal volume. Cortisol-WM relationships were modest, as was the degree to which WM structure attenuated cortisol-cognition associations (<15%). These data support the hypothesis that GCs contribute to cognitive ageing differences from childhood to the early 70s, partly via brain WM structure.

  11. Alternative life histories in Xiphophorus multilineatus: evidence for different ages at sexual maturity and growth responses in the wild.

    PubMed

    Bono, L M; Rios-Cardenas, O; Morris, M R

    2011-05-01

    In order to examine potential trade-offs in alternative life histories of the high-backed pygmy swordtail Xiphophorus multilineatus, otoliths were used from wild-caught males to determine if sneaker males had the advantage of maturing earlier in natural environments. The sneakers matured significantly earlier than courters, but there was no difference among the three courter variants. In addition, analyses suggested that the effect of the pituitary locus on size at sexual maturity and growth rates was a consequence of age at sexual maturity. Finally, one of the courter variants had a significantly different relationship between age and size at sexual maturity than the other variants, suggesting that in this variant, age at sexual maturity may be more closely related to size and therefore may be less plastic in its growth responses.

  12. Effect of aging on GHRF-induced growth hormone release from anterior pituitary cells in primary culture

    SciTech Connect

    Spik, K.W.; Boyd, R.L.; Sonntag, W.E.

    1991-03-01

    Five criteria were developed to validate the primary cell culture model for comparison of GRF-induced release of growth hormone in pituitary tissue from aging animals. Pituitaries from young (5-mo), middle-aged (14-mo), and old (24-mo) male Fischer 344 rats were dispersed using either trypsin/trypsin inhibitor or dispase and compared with respect to the number of pituitary cells recovered, cell viability, 3H-leucine incorporation into total protein, time course for recovery of optimal response to GRF, and the dose-relationship for GRF-induced release of growth hormone 2, 4, and 6 days after dispersal. Results indicated that direct comparison of cellular responses between tissues from young, middle-aged, and old rats in primary cell culture is confounded by variations in time for recovery of optimal responses, the effects of the enzymes used for dispersal, and the methods used to express the data.

  13. Growth and mortality of age-0 northern squawfish, Ptychocheilus oregonensis, rearing in shoreline habitats of the Columbia River Reservoir

    USGS Publications Warehouse

    Barfoot, C.A.; Gadomski, D.M.; Wertheimer, R.H.

    1999-01-01

    We investigated growth and mortality of age-0 northern squawfish during early rearing in shallow shoreline habitats. Larvae and juveniles (n=22914) were collected by weekly seining at three sample sites in the upper John Day Reservoir, Columbia River, during June through early September 1994–1996. Using a length-based ageing method, it was estimated that the exponential growth rate (G) for a common growth stanza (10–28 mm standard length SL) was significantly higher in 1994 (G=0.047) than in 1996 (G=0.037). Growth rate in 1995 could not be estimated, but was probably intermediate between 1994 and 1996 based on mean standard lengths of fish collected at the end of each sampling season (46.3, 40.0, and 32.0 mm SL in 1994, 1995, and 1996, respectively). For many fish species, variations in early growth can influence survival through size-selective mortality processes. Consistent with this possibility, our estimates of instantaneous mortality rates (Z) demonstrated that larvae and juveniles had significantly higher mortality in 1996 than in 1994 (Z=0.103 in 1994, versus Z=0.138 in 1996). Enhanced growth and lower mortality in 1994 were associated with a number of interrelated environmental conditions – comparatively low flows and turbidities, abundant instream vegetative cover, and high near-shore water temperatures.

  14. Ambient aging of rhenium filaments used in thermal ionization mass spectrometry: Growth of oxo-rhenium crystallites and anti-aging strategies.

    PubMed

    Mannion, Joseph M; Wellons, Matthew S; Shick, Charles R; Fugate, Glenn A; Powell, Brian A; Husson, Scott M

    2017-01-01

    Degassing is a common preparation technique for rhenium filaments used for thermal ionization mass spectrometric analysis of actinides, including plutonium. Although optimization studies regarding degassing conditions have been reported, little work has been done to characterize filament aging after degassing. In this study, the effects of filament aging after degassing were explored to determine a "shelf-life" for degassed rhenium filaments, and methods to limit filament aging were investigated. Zone-refined rhenium filaments were degassed by resistance heating under high vacuum before exposure to ambient atmosphere for up to 2 months. After degassing the nucleation and preferential growth of oxo-rhenium crystallites on the surface of polycrystalline rhenium filaments was observed by atomic force microscopy and scanning electron microscopy (SEM). Compositional analysis of the crystallites was conducted using SEM-Raman spectroscopy and SEM energy dispersive X-ray spectroscopy, and grain orientation at the metal surface was investigated by electron back-scatter diffraction mapping. Spectra collected by SEM-Raman suggest crystallites are composed primarily of perrhenic acid. The relative extent of growth and crystallite morphology were found to be grain dependent and affected by the dissolution of carbon into filaments during annealing (often referred to as carbonization or carburization). Crystallites were observed to nucleate in region specific modes and grow over time through transfer of material from the surface. Factors most likely to affect the rates of crystallite growth include rhenium substrate properties such as grain size, orientation, levels of dissolved carbon, and relative abundance of defect sites; as well as environmental factors such as length of exposure to oxygen and relative humidity. Thin (∼180 nm) hydrophobic films of poly(vinylbenzyl chloride) were found to slow the growth of oxo-rhenium crystallites on the filament surfaces and may serve as

  15. Mercury Exposure in Healthy Korean Weaning-Age Infants: Association with Growth, Feeding and Fish Intake.

    PubMed

    Chang, Ju Young; Park, Jeong Su; Shin, Sue; Yang, Hye Ran; Moon, Jin Soo; Ko, Jae Sung

    2015-11-17

    Low-level mercury (Hg) exposure in infancy might be harmful to the physical growth as well as neurodevelopment of children. The aim of this study was to investigate postnatal Hg exposure and its relationship with anthropometry and dietary factors in late infancy. We recruited 252 healthy Korean infants between six and 24 months of age from an outpatient clinic during the 2009/2010 and 2013/2014 seasons. We measured the weight and height of the infants and collected dietary information using questionnaires. The Hg content of the hair and blood was assessed using inductively coupled plasma mass spectroscopy. The geometric mean Hg concentration in the hair and blood was 0.22 (95% confidence interval: 0.20-0.24) µg/g and 0.94 (n = 109, 95% confidence interval: 0.89-0.99) µg/L, respectively. The hair Hg concentration showed a good correlation with the blood Hg concentration (median hair-to-blood Hg ratio: 202.7, r = 0.462, p < 0.001) and was >1 µg/g in five infants. The hair Hg concentration showed significant correlations with weight gain after birth (Z-score of the weight for age-Z-score of the birthweight; r = -0.156, p = 0.015), the duration (months) of breastfeeding as the dominant method of feeding (r = 0.274, p < 0.001), and the duration of fish intake more than once per week (r = 0.138, p = 0.033). In an ordinal logistic regression analysis with categorical hair Hg content (quartiles), dietary factors, including breastfeeding as the dominant method of feeding in late infancy (cumulative odds ratio: 6.235, 95% confidence interval: 3.086-12.597, p < 0.001) and the monthly duration of fish intake more than once per week (cumulative odds ratio: 1.203, 95% confidence interval: 1.034-1.401; p = 0.017), were significantly associated with higher hair Hg content. Weight gain after birth was not, however, significantly associated with hair Hg content after adjustment for the duration of breastfeeding as the dominant method of feeding. Low-level Hg exposure through

  16. Effect of maternal age and growth on placental nutrient transport: potential mechanisms for teenagers' predisposition to small-for-gestational-age birth?

    PubMed

    Hayward, Christina E; Greenwood, Susan L; Sibley, Colin P; Baker, Philip N; Challis, John R G; Jones, Rebecca L

    2012-01-15

    Teenagers have an increased risk of delivering small-for-gestational-age (SGA) infants. Young maternal age and continued skeletal growth have been implicated as causal factors. In growing adolescent sheep, impaired placental development and nutrient transfer cause reduced birth weight. In human pregnancies, SGA is associated with reduced placental amino acid transport. Maternal growth has no effect on placental morphology or cell turnover, but growing teenagers have higher birth weight:placental weight ratios than nongrowing teenagers. We hypothesized that placental nutrient transporter activity would be affected by maternal age and/or growth status. Placentas from teenagers and adults were collected. Teenagers were defined as growing or nongrowing based on knee height measurements. System A amino acid transporter activity was quantified as sodium-dependent uptake of [(14)C]methylaminoisobutyric acid into placental fragments. Teenagers had lower placental system A activity than adults (P < 0.05). In adults, placental system A activity was lower in SGA infants than appropriate-for-gestational-age (AGA) infants (P < 0.05). In teenagers, AGA and SGA infants had lower placental system A activity than AGA infants born to adults (P < 0.05). Placental system A activity was higher in growing teenagers than in nongrowing teenagers (P < 0.001). Placental mRNA expression of system A transporter isoforms SLC38A1 and -2 was lower in teenagers than in adults (P < 0.05) but did not differ between growing and nongrowing teenagers. There was no difference in transporter protein expression/localization between cohorts. Teenagers have inherently reduced placental transport, which may underlie their susceptibility to delivering SGA infants. Growing teenagers appear to overcome this susceptibility by stimulating the activity, but not expression, of system A transporters.

  17. Modeling Elementary Aged Students' Fluency Growth in Written Expression: Predicting Fluency Growth for Girls and Boys in General Education

    ERIC Educational Resources Information Center

    Truckenmiller, Adrea J.

    2011-01-01

    Research on evidence-based writing intervention practices as well as reliable and valid assessments of elementary-aged students' writing fluency has been lacking compared to other academic areas (i.e., reading). Performance feedback interventions targeting writing fluency are gaining empirical support (Eckert et al., 2006); however, growth…

  18. Looking for age-related growth decline in natural forests: unexpected biomass patterns from tree rings and simulated mortality

    USGS Publications Warehouse

    Foster, Jane R.; D'Amato, Anthony W.; Bradford, John B.

    2014-01-01

    Forest biomass growth is almost universally assumed to peak early in stand development, near canopy closure, after which it will plateau or decline. The chronosequence and plot remeasurement approaches used to establish the decline pattern suffer from limitations and coarse temporal detail. We combined annual tree ring measurements and mortality models to address two questions: first, how do assumptions about tree growth and mortality influence reconstructions of biomass growth? Second, under what circumstances does biomass production follow the model that peaks early, then declines? We integrated three stochastic mortality models with a census tree-ring data set from eight temperate forest types to reconstruct stand-level biomass increments (in Minnesota, USA). We compared growth patterns among mortality models, forest types and stands. Timing of peak biomass growth varied significantly among mortality models, peaking 20–30 years earlier when mortality was random with respect to tree growth and size, than when mortality favored slow-growing individuals. Random or u-shaped mortality (highest in small or large trees) produced peak growth 25–30 % higher than the surviving tree sample alone. Growth trends for even-aged, monospecific Pinus banksiana or Acer saccharum forests were similar to the early peak and decline expectation. However, we observed continually increasing biomass growth in older, low-productivity forests of Quercus rubra, Fraxinus nigra, and Thuja occidentalis. Tree-ring reconstructions estimated annual changes in live biomass growth and identified more diverse development patterns than previous methods. These detailed, long-term patterns of biomass development are crucial for detecting recent growth responses to global change and modeling future forest dynamics.

  19. Looking for age-related growth decline in natural forests: unexpected biomass patterns from tree rings and simulated mortality.

    PubMed

    Foster, Jane R; D'Amato, Anthony W; Bradford, John B

    2014-05-01

    Forest biomass growth is almost universally assumed to peak early in stand development, near canopy closure, after which it will plateau or decline. The chronosequence and plot remeasurement approaches used to establish the decline pattern suffer from limitations and coarse temporal detail. We combined annual tree ring measurements and mortality models to address two questions: first, how do assumptions about tree growth and mortality influence reconstructions of biomass growth? Second, under what circumstances does biomass production follow the model that peaks early, then declines? We integrated three stochastic mortality models with a census tree-ring data set from eight temperate forest types to reconstruct stand-level biomass increments (in Minnesota, USA). We compared growth patterns among mortality models, forest types and stands. Timing of peak biomass growth varied significantly among mortality models, peaking 20-30 years earlier when mortality was random with respect to tree growth and size, than when mortality favored slow-growing individuals. Random or u-shaped mortality (highest in small or large trees) produced peak growth 25-30% higher than the surviving tree sample alone. Growth trends for even-aged, monospecific Pinus banksiana or Acer saccharum forests were similar to the early peak and decline expectation. However, we observed continually increasing biomass growth in older, low-productivity forests of Quercus rubra, Fraxinus nigra, and Thuja occidentalis. Tree-ring reconstructions estimated annual changes in live biomass growth and identified more diverse development patterns than previous methods. These detailed, long-term patterns of biomass development are crucial for detecting recent growth responses to global change and modeling future forest dynamics.

  20. Current status of vascular endothelial growth factor inhibition in age-related macular degeneration.

    PubMed

    Mousa, Shaker A; Mousa, Shaymaa S

    2010-06-01

    Angiogenesis, the process by which new vessels are created from pre-existing vasculature, has become the subject of intense research in recent years. Increased rates of angiogenesis are associated with several disease states, including cancer, age-related macular degeneration (AMD), psoriasis, rheumatoid arthritis, and diabetic retinopathy. Vascular endothelial growth factor (VEGF) is an important modulator of angiogenesis, and has been implicated in the pathology of a number of conditions, including AMD, diabetic retinopathy, and cancer. AMD is a progressive disease of the macula and the third major cause of blindness worldwide. If not treated appropriately, AMD can progress to involve both eyes. Until recently, the treatment options for AMD have been limited, with photodynamic therapy (PDT) the mainstay of treatment. Although PDT is effective at slowing disease progression, it rarely results in improved vision. Several therapies have been or are now being developed for neovascular AMD, with the goal of inhibiting VEGF. These VEGF inhibitors include the RNA aptamer pegaptanib, partial and full-length antibodies ranibizumab and bevacizumab, the VEGF receptor decoy aflibercept, small interfering RNA-based therapies bevasiranib and AGN 211745, sirolimus, and tyrosine kinase inhibitors, including vatalanib, pazopanib, TG 100801, TG 101095, AG 013958, and AL 39324. At present, established therapies have met with great success in reducing the vision loss associated with neovascular AMD, whereas those still under investigation offer the potential for further advances. In AMD patients, these therapies slow the rate of vision loss and in some cases increase visual acuity. Although VEGF-inhibitor therapies are a milestone in the treatment of these disease states, several concerns need to be addressed before their impact can be fully realized.

  1. The aging suppressor klotho: a potential regulator of growth hormone secretion.

    PubMed

    Shahmoon, Shiri; Rubinfeld, Hadara; Wolf, Ido; Cohen, Zvi R; Hadani, Moshe; Shimon, Ilan; Rubinek, Tami

    2014-08-01

    Klotho is a transmembranal protein highly expressed in the kidneys, choroid plexus, and anterior pituitary. Klotho can also be cleaved and shed and acts as a circulating hormone. Klotho-deficient mice (kl/kl mice) develop a phenotype resembling early aging. Several lines of evidence suggest a role for klotho in the regulation of growth hormone (GH) secretion. The kl/kl mice are smaller compared with their wild-type counterparts, and their somatotropes show reduced numbers of secretory granules. Moreover, klotho is a potent inhibitor of the IGF-I pathway, a negative regulator of GH secretion. Therefore, we hypothesized that klotho may enhance GH secretion. The effect of klotho on GH secretion was examined in GH3 rat somatotrophs, cultured rat pituitaries, and cultured human GH-secreting adenomas. In all three models, klotho treatment increased GH secretion. Prolonged treatment of mice with intraperitoneal klotho injections increased mRNA levels of IGF-I and IGF-I-binding protein-3 mRNA in the liver, reflecting increased serum GH levels. In accord with its ability to inhibit the IGF-I pathway, klotho partially restored the inhibitory effect of IGF-I on GH secretion. Klotho is known to be a positive regulator of basic bFGF signaling. We studied rat pituitaries and human adenoma cultures and noted that bFGF increased GH secretion and stimulated ERK1/2 phosphorylation. Both effects were augmented following treatment with klotho. Taken together, our data indicate for the first time that klotho is a positive regulator of GH secretion and suggest the IGF-I and bFGF pathways as potential mediators of this effect.

  2. Age and growth of the common goby, Pomatoschistus microps, on the south coast of England

    NASA Astrophysics Data System (ADS)

    Fouda, M. M.; Miller, P. J.

    1981-02-01

    Seasonal changes in scale appearance and body growth pattern have been studied in a Teign Estuary (Devon) population of the common goby, Pomatoschistus microps (Kroyer), with additional material from St. Anthony, on Gillan Harbour, Cornwall. Examination of caudal peduncle scales showed similarity in annulus formation with other populations earlier investigated around the British Isles. The time of scale annulus formation in the Teign estuary was established from monthly changes in mean terminal sclerite width. After the first winter of life, an annulus of narrow sclerites is produced on resumption of growth in spring, and a second annulus laid down in summer between early June and August, corresponding to growth retardation during the peak of the long breeding season (April to August). The growth pattern shows a period of rapid growth in immature fish during the first summer and early autumn of life and declines or ceases in late autumn and winter. Vigorous resumption of growth in spring and early summer is followed by a decline in growth rate during the peak breeding season, and then growth recovery in September and October. Change in monthly mean terminal sclerite width of scales reflects somewhat earlier changes in somatic growth. Back-calculated growth suggests a static population during the breeding season. Various influences on growth are noted, including reproduction and scale regeneration.

  3. Otoliths reveal a diverse age structure for humper lake trout in Lake Superior

    USGS Publications Warehouse

    Burnham-Curtis, Mary K.; Bronte, Charles R.

    1996-01-01

    Humpers are one of at least three morphological variants of wild lake trout Salvelinus namaycush that maintain self-sustaining populations in Lake Superior. In an early study, bumpers from Isle Royale were shown to have a sharply truncated age distribution that was attributed to high mortality after age 11, but we suspected that these fish were underaged. In August of 1989 and 1992 we collected spawning humper lake trout from the same area and estimated their ages using both scales and sagittal otoliths. Humpers in our sample ranged from 5 to 13 years, based on scale annuli, but counts of sagitta annuli revealed ages of 8 to 28 years. Individual discrepancies between ages from scales and sagittae varied from –2 to 20 years, but differences between scale and otolith ages did not increase with individual age. We applied the von Bertalanffy growth model to the humper length-at-age data to indirectly assess the accuracy of aging estimates. The model significantly overestimated mean asymptotic length when scale ages were used, but the mean asymptotic length estimate was more similar to observed lengths when sagitta ages were used. Our results corroborate evidence that bumpers in Lake Superior grow more slowly and mature at a smaller size than lean lake trout; however, the age composition of bumpers is more diverse than previously thought. This particular population experiences little or no exploitation; the presence of older fish provides one standard by which the success of lake trout rehabilitation programs can be evaluated and emphasizes the need for accurate aging techniques.

  4. Growth-Hormone Dynamics in Healthy Adults are Related to Age and Sex, and Strongly Dependent on Body Mass Index

    PubMed Central

    Roelfsema, Ferdinand; Veldhuis, Johannes D.

    2015-01-01

    Context Studies on 24-hour growth hormone (GH) secretion are rare. The influence of sex, age and adiposity are well recognized but generally derived from specific selected subject groups, not spanning sexes, many age decades, and a range of body weights. Objective The goal was to investigate GH dynamics in a group of 130 healthy adult subjects, both men and women, across 5 age decades, and a 2.5 fold range of body mass index (BMI). Methods GH was measured by a sensitive immunofluorometric assay. Secretion parameters were quantified by automated deconvolution and relative pattern randomness by approximate entropy (ApEn). Results Median age was 40, range 20–77 year. Median BMI was 26, range 18.3–49.8 kg/m2. Pulsatile 24-hour GH secretion was negatively correlated with age (P=0.002) and BMI (P<0.0001). Basal GH secretion negatively correlated with BMI (P=0.003) and not with age. The sex-dependent GH secretion (larger in women) was no longer detectable after 50 year. IGF-1 levels were lower in women after 50 year compared with men of similar age. ApEn showed age-related increase in both sexes and was higher in premenopausal and postmenopausal women than men of comparable age (P<0.0001). A single fasting GH measurement is non-informative of 24-hour GH secretion. Conclusion BMI dominates the negative regulation of 24-hour GH secretion across 5 decades of age in this till now largest cohort of healthy adults, who underwent 24-hour blood sampling. Sex also impacts GH secretion before age 50 yr and its regularity at all ages. Serum IGF-I differences partly depend on pre- or postmenopausal state. Finally, a single GH measurement is not informative of 24-hour GH secretion. PMID:26228064

  5. Effect of growth rate from 6 to 16 months of age on sexual development and reproductive function in beef bulls.

    PubMed

    Brito, L F C; Barth, A D; Wilde, R E; Kastelic, J P

    2012-04-15

    Sexual development and reproductive function were studied in 22 Angus × Charolais and 17 Angus bulls from 6 to 16 mo of age. Associations of average daily gain (ADG) and body weight with ages at puberty and at maturity (satisfactory semen quality), scrotal circumference, paired-testes volume and weight, testicular vascular cone diameter and fat thickness, scrotal temperature, sperm production and morphology, and testicular histology, were determined. There were no significant correlations between cumulative average daily gain and any of the end points investigated. Body weight at various ages was negatively correlated with ages at puberty and maturity in Angus × Charolais bulls, positively correlated with paired-testes weight in Angus × Charolais and Angus bulls, and positively correlated with seminiferous tubule volume in Angus bulls (P < 0.05). Semen quality improved gradually with age and the interval between puberty and maturity (mean ± SD; 309.4 ± 29.7 and 357 ± 42 days of age) was approximately 50 days. Age, weight, scrotal circumference, and paired-testes volume were all good predictors of pubertal and mature status, with moderate to high sensitivity and specificity (71.6% to 92.4%). In summary, growth rate between 6 and 16 mo of age did not affect sexual development and reproductive function in beef bulls. However, greater body weight at various ages was associated with reduced age at puberty and maturity, and with larger testes at 16 mo of age, indicating that improved nutrition might be beneficial, but only when offered before 6 mo of age. Average daily gains of approximately 1 to 1.6 kg/day did not result in excessive fat accumulation in the scrotum, increased scrotal temperature, or reduction in sperm production and semen quality, and could be considered "safe" targets for growing beef bulls.

  6. Heparin localization and fine structure regulate Burkitt's lymphoma growth

    SciTech Connect

    Berry, David; Lynn, David M.; Berry, Eric; Sasisekharan, Ram; Langer, Robert . E-mail: rlanger@mit.edu

    2006-09-29

    Burkitt's lymphoma (BL) is a B-cell malignancy associated with the Epstein-Barr virus (EBV). Mounting evidence has implicated heparan sulfate proteoglycans and heparan sulfate-like glycosaminoglycans (HSGAGs) in the initiation, severity, and progression of the malignancy. The importance of HSGAGs in regulating BL cell growth was therefore examined. Extracellular exogenous heparin inhibited cell growth >30%, while heparin internalized with poly({beta}-amino ester)s promoted proliferation up to 58%. The growth-modulating effects of heparin and internalized heparin were dependent on cell surface HSGAGs, PI3K, and Erk/Mek. Treatment of cells with protamine sulfate or with heparinases potently inhibited proliferation, with the greatest effects induced by heparinase I. Cell surface HSGAGs therefore play an important role in regulating BL proliferation and may offer a potential target for therapeutic intervention.

  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. Mathematical Model of Three Age-Structured Transmission Dynamics of Chikungunya Virus

    PubMed Central

    Agusto, Folashade B.; Easley, Shamise; Freeman, Kenneth; Thomas, Madison

    2016-01-01

    We developed a new age-structured deterministic model for the transmission dynamics of chikungunya virus. The model is analyzed to gain insights into the qualitative features of its associated equilibria. Some of the theoretical and epidemiological findings indicate that the stable disease-free equilibrium is globally asymptotically stable when the associated reproduction number is less than unity. Furthermore, the model undergoes, in the presence of disease induced mortality, the phenomenon of backward bifurcation, where the stable disease-free equilibrium of the model coexists with a stable endemic equilibrium when the associated reproduction number is less than unity. Further analysis of the model indicates that the qualitative dynamics of the model are not altered by the inclusion of age structure. This is further emphasized by the sensitivity analysis results, which shows that the dominant parameters of the model are not altered by the inclusion of age structure. However, the numerical simulations show the flaw of the exclusion of age in the transmission dynamics of chikungunya with regard to control implementations. The exclusion of age structure fails to show the age distribution needed for an effective age based control strategy, leading to a one size fits all blanket control for the entire population. PMID:27190548

  9. Aging Influence on Gray Matter Structural Associations within the Default Mode Network Utilizing Bayesian Network Modeling.

    PubMed

    Wang, Yan; Chen, Kewei; Zhang, Jiacai; Yao, Li; Li, Ke; Jin, Zhen; Ye, Qing; Guo, Xiaojuan

    2014-01-01

    Recent neuroimaging studies have revealed normal aging-related alterations in functional and structural brain networks such as the default mode network (DMN). However, less is understood about specific brain structural dependencies or interactions between brain regions within the DMN in the normal aging process. In this study, using Bayesian network (BN) modeling, we analyzed gray matter volume data from 109 young and 82 old subjects to characterize the influence of aging on associations between core brain regions within the DMN. Furthermore, we investigated the discriminability of the aging-associated BN models for the young and old groups. Compared to their young counterparts, the old subjects showed significant reductions in connections from right inferior temporal cortex (ITC) to medial prefrontal cortex (mPFC), right hippocampus (HP) to right ITC, and mPFC to posterior cingulate cortex and increases in connections from left HP to mPFC and right inferior parietal cortex to right ITC. Moreover, the classification results showed that the aging-related BN models could predict group membership with 88.48% accuracy, 88.07% sensitivity, and 89.02% specificity. Our findings suggest that structural associations within the DMN may be affected by normal aging and provide crucial information about aging effects on brain structural networks.

  10. The effects of prenatal methamphetamine exposure on childhood growth patterns from birth to 3 years of age.

    PubMed

    Zabaneh, Rachel; Smith, Lynne M; LaGasse, Linda L; Derauf, Chris; Newman, Elana; Shah, Rizwan; Arria, Amelia; Huestis, Marilyn; Haning, William; Strauss, Arthur; Della Grotta, Sheri; Dansereau, Lynne M; Lin, Hai; Neal, Charles; Lester, Barry M

    2012-03-01

    We examined the effects of prenatal methamphetamine (MA) exposure on growth parameters from birth to age 3 years. The 412 subjects included (n = 204 exposed) were enrolled at birth in the Infant Development, Environment and Lifestyle study, a longitudinal study assessing the effects of prenatal MA exposure on childhood outcomes. Individual models were used to examine the effects of prenatal MA exposure on weight, head circumference, height, and weight-for-length growth trajectories. After adjusting for covariates, height trajectory was lower in the exposed versus the comparison children (p = 0.021) over the first 3 years of life. Both groups increased height on average by 2.27 cm per month by age 3 years. In term subjects, MA exposure was also associated with a lower height trajectory (p = 0.034), with both the exposed and comparison groups gaining 2.25 cm per month by age 3 years. There was no difference in weight, head circumference, or weight-for-length growth trajectories between the comparison and the exposed groups. Children exposed prenatally to MA have a modest decrease in height growth trajectory during the first 3 years of life with no observed difference in weight, head circumference, or weight-for-length trajectories.

  11. Metallic Catalysts for Structure-Controlled Growth of Single-Walled Carbon Nanotubes.

    PubMed

    Li, Meihui; Liu, Xiyan; Zhao, Xiulan; Yang, Feng; Wang, Xiao; Li, Yan

    2017-04-01

    Single-walled carbon nanotubes (SWNTs) have shown great potential in various applications attributed to their unique structures and outstanding structure-dependent properties. The structure-controlled growth of SWNTs is a crucial issue for their advanced applications and has been a great challenge in this field for two decades. Metal catalyst-mediated SWNT growth is believed to be very efficient. In this review, progresses in diameter and chirality controlled growth of SWNTs with metal catalysts is summarized from several aspects, including growth mechanism and theory, effects of catalysts, and the chemical vapor deposition conditions. The design, preparation, handling and dispersion, and the size evolution of metal catalysts are all discussed. The influences of growth environment including the type, composition, and pressure/concentration of the carbon source as well as the temperature on the selectivity toward the nanotube structure are analyzed. We also discuss some of the challenges and trends in this field.

  12. Quota implementation of the maximum sustainable yield for age-structured fisheries.

    PubMed

    Kanik, Zafer; Kucuksenel, Serkan

    2016-06-01

    One of the main goals stated in the proposals for the Common Fisheries Policy (CFP) reform was achieving maximum sustainable yield (MSY) for all European fisheries. In this paper, we propose a fishing rights allocation mechanism or management system, which specifies catch limits for individual fishing fleets to implement MSY harvesting conditions in an age-structured bioeconomic model. An age-structured model in a single species fishery with two fleets having perfect or imperfect fishing selectivity is studied. If fishing technology or gear selectivity depends on the relative age composition of the mature fish stock, fixed harvest proportions, derived from catchability and bycatch coefficients, is not valid anymore. As a result, not only the age-structure and fishing technology but also the estimated level of MSY is steering the allocation of quota shares. The results also show that allocation of quota shares based on historical catches or auctioning may not provide viable solutions to achieve MSY.

  13. Plasmodium falciparum infection and age influence parasite growth inhibition mediated by IgG in Beninese infants.

    PubMed

    Adamou, Rafiou; Chénou, Francine; Sadissou, Ibrahim; Sonon, Paulin; Dechavanne, Célia; Djilali-Saïah, Abdelkader; Cottrell, Gilles; Le Port, Agnès; Massougbodji, Achille; Remarque, Edmond J; Luty, Adrian J F; Sanni, Ambaliou; Garcia, André; Migot-Nabias, Florence; Milet, Jacqueline; Courtin, David

    2016-07-01

    Antibodies that impede the invasion of Plasmodium falciparum (P. falciparum) merozoites into erythrocytes play a critical role in anti-malarial immunity. The Growth Inhibition Assay (GIA) is an in vitro measure of the functional capacity of such antibodies to limit erythrocyte invasion and/or parasite growth. Up to now, it is unclear whether growth-inhibitory activity correlates with protection from clinical disease and there are inconsistent results from studies performed with GIA. Studies that have focused on the relationship between IgGs and their in vitro parasite Growth Inhibition Activity (GIAc) in infants aged less than two years old are rare. Here, we used clinical and parasitological data to precisely define symptomatic or asymptomatic infection with P. falciparum in groups of infants followed-up actively for 18 months post-natally. We quantified the levels of IgG1 and IgG3 directed to a panel of candidate P. falciparum vaccine antigens (AMA-1, MSP1, 2, 3 and GLURP) using ELISA and the functional activity of IgG was quantified using GIA. Data were then correlated with individuals' infection status. At 18 months of age, infants harbouring infections at the time of blood sampling had an average 19% less GIAc than those not infected (p=0.004, multivariate linear regression). GIAc decreased from 12 to 18 months of age (p=0.003, Wilcoxon matched pairs test). Antibody levels quantified at 18 months in infants were strongly correlated with their exposure to malarial infection, however GIAc was not correlated with malaria infectious status (asymptomatic and symptomatic groups). In conclusion, both infection status at blood draw and age influence parasite growth inhibition mediated by IgG in the GIA. Both factors must be taken into account when correlations between GIAc and anti-malarial protection or vaccine efficacy have to be made.

  14. Growth, defect structure, and THz application of stoichiometric lithium niobate

    SciTech Connect

    Lengyel, K.; Péter, Á.; Kovács, L.; Corradi, G.; Dravecz, G.; Hajdara, I.; Szaller, Zs.; Polgár, K.; Pálfalvi, L.; Unferdorben, M.; Hebling, J.

    2015-12-15

    Owing to the extraordinary richness of its physical properties, congruent lithium niobate has attracted multidecade-long interest both for fundamental science and applications. The combination of ferro-, pyro-, and piezoelectric properties with large electro-optic, acousto-optic, and photoelastic coefficients as well as the strong photorefractive and photovoltaic effects offers a great potential for applications in modern optics. To provide powerful optical components in high energy laser applications, tailoring of key material parameters, especially stoichiometry, is required. This paper reviews the state of the art of growing large stoichiometric LiNbO{sub 3} (sLN) crystals, in particular, the defect engineering of pure and doped sLN with emphasis on optical damage resistant (ODR) dopants (e.g., Mg, Zn, In, Sc, Hf, Zr, Sn). The discussion is focused on crystals grown by the high temperature top seeded solution growth (HTTSSG) technique using alkali oxide fluxing agents. Based on high-temperature phase equilibria studies of the Li{sub 2}O–Nb{sub 2}O{sub 5}–X{sub 2}O ternary systems (X = Na, K, Rb, Cs), the impact of alkali homologue additives on the stoichiometry of the lithium niobate phase will be analyzed, together with a summary of the ultraviolet, infrared, and far-infrared absorption spectroscopic methods developed to characterize the composition of the crystals. It will be shown that using HTTSSG from K{sub 2}O containing flux, crystals closest to the stoichiometric composition can be grown characterized by a UV-edge position of at about 302 nm and a single narrow hydroxyl band in the IR with a linewidth of less than 3 cm{sup −1} at 300 K. The threshold concentrations for ODR dopants depend on crystal stoichiometry and the valence of the dopants; Raman spectra, hydroxyl vibration spectra, and Z-scan measurements prove to be useful to distinguish crystals below and above the photorefractive threshold. Crystals just above the threshold are

  15. Age and growth of filefish, Thamnaconus modestus (Günther, 1877) off the Jeju Island of Korea

    NASA Astrophysics Data System (ADS)

    Kim, AhReum; Bae, HoJin; Kim, Hyeong-Gi; Oh, Chul-Woong

    2016-09-01

    The age and growth of filefish, Thamnaconus modestus (Günther 1877) in the southern waters of Korea were investigated. Samples were collected with commercial trawl catches during the period from May 2009 to December 2011. Of the 2,626 specimens collected, the sex ratio was not significantly different from 1:1 ( P > 0.05). The total length ranged from 11.3 to 42.1 cm. The gonadosomatic index for both sexes was the highest in May to June, indicating that May to June is the main spawning period. The length of females at sexual maturity was 25.92 cm. The length-weight relationship of the filefish was TW = 0.0121TL3.0536 ( n = 1,692, r 2 = 0.9034, P < 0.001). The age of the sampled individuals was estimated by counting growth rings recorded on the 5th vertebrae; ages ranged from 0 to 9 years. The filefish of the same age displayed a high individual variation in total length. Length-at-age data were fitted by using the Von Bertalanffy growth model. The estimated Von Bertalanffy growth parameters were L ∞ = 42.04 cm, k = 0.21 year-1 and t0 = -1.56 for females, L ∞ = 41.20 cm, k = 0.18 year-1 and t0 = -2.36 for males, and L ∞ = 43.16 cm, k = 0.17 year-1 and t0 = -2.18 for the combination of both male and female. These data can be used as useful biological information for the future fishery management of filefish resources in Korean waters.

  16. 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.

  17. Structural Validity of the Movement ABC-2 Test: Factor Structure Comparisons across Three Age Groups

    ERIC Educational Resources Information Center

    Schulz, Joerg; Henderson, Sheila E.; Sugden, David A.; Barnett, Anna L.

    2011-01-01

    Background: The Movement ABC test is one of the most widely used assessments in the field of Developmental Coordination Disorder (DCD). Improvements to the 2nd edition of the test (M-ABC-2) include an extension of the age range and reduction in the number of age bands as well as revision of tasks. The total test score provides a measure of motor…

  18. Structural Validity of the Professional Development Profile of the LoTi Digital-Age Survey

    ERIC Educational Resources Information Center

    Mehta, Vandhana; Hull, Darrell M.

    2013-01-01

    The present study was used to examine the structural construct validity of the Professional Development Profile of the LoTi Digital-Age Survey, a measure of teacher instructional practices with technology in the classroom. Teacher responses ("N" = 2,840) from across the United States were used to assess factor structure of the instrument…

  19. Structural brain differences in school-age children with and without single-suture craniosynostosis.

    PubMed

    Aldridge, Kristina; Collett, Brent R; Wallace, Erin R; Birgfeld, Craig; Austin, Jordan R; Yeh, Regina; Feil, Madison; Kapp-Simon, Kathleen A; Aylward, Elizabeth H; Cunningham, Michael L; Speltz, Matthew L

    2017-04-01

    OBJECTIVE Single-suture craniosynostosis (SSC), the premature fusion of a cranial suture, is characterized by dysmorphology of the craniofacial skeleton. Evidence to suggest that children with SSC are at an elevated risk of mild to moderate developmental delays and neurocognitive deficits is mounting, but the associations among premature suture fusion, neuroanatomy, and neurocognition are unexplained. The goals of this study were to determine 1) whether differences in the brain are present in young children with the 2 most common forms of SSC (sagittal and metopic) several years following surgical correction, and 2) whether the pattern of differences varies by affected suture (sagittal or metopic). Examination of differences in the brains of children with SSC several years after surgery may illuminate the growth trajectory of the brain after the potential constraint of the dysmorphic cranium has been relieved. METHODS The authors compared quantitative measures of the brain acquired from MR images obtained from children with sagittal or metopic craniosynostosis (n = 36) at 7 years of age to those obtained from a group of unaffected controls (n = 27) at the same age. The authors measured the volumes of the whole brain, cerebral cortex, cerebral white matter, cerebral cortex by lobe, and ventricles. Additionally, they measured the midsagittal area of the corpus callosum and its segments and of the cerebellar vermis and its component lobules. Measurements obtained from children with SSC and controls were compared using linear regression models. RESULTS No volume measures of the cerebrum or of the whole brain differed significantly between patients with SSC and controls (p > 0.05). However, ventricle volume was significantly increased in patients with SSC (p = 0.001), particularly in those with sagittal craniosynostosis (p < 0.001). In contrast, the area of the corpus callosum was significantly reduced in patients with metopic synostosis (p = 0.04), particularly in the

  20. Growth

    NASA Astrophysics Data System (ADS)

    Waag, Andreas

    This chapter is devoted to the growth of ZnO. It starts with various techniques to grow bulk samples and presents in some detail the growth of epitaxial layers by metal organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), and pulsed laser deposition (PLD). The last section is devoted to the growth of nanorods. Some properties of the resulting samples are also presented. If a comparison between GaN and ZnO is made, very often the huge variety of different growth techniques available to fabricate ZnO is said to be an advantage of this material system. Indeed, growth techniques range from low cost wet chemical growth at almost room temperature to high quality MOCVD growth at temperatures above 1, 000∘C. In most cases, there is a very strong tendency of c-axis oriented growth, with a much higher growth rate in c-direction as compared to other crystal directions. This often leads to columnar structures, even at relatively low temperatures. However, it is, in general, not straight forward to fabricate smooth ZnO thin films with flat surfaces. Another advantage of a potential ZnO technology is said to be the possibility to grow thin films homoepitaxially on ZnO substrates. ZnO substrates are mostly fabricated by vapor phase transport (VPT) or hydrothermal growth. These techniques are enabling high volume manufacturing at reasonable cost, at least in principle. The availability of homoepitaxial substrates should be beneficial to the development of ZnO technology and devices and is in contrast to the situation of GaN. However, even though a number of companies are developing ZnO substrates, only recently good quality substrates have been demonstrated. However, these substrates are not yet widely available. Still, the situation concerning ZnO substrates seems to be far from low-cost, high-volume production. The fabrication of dense, single crystal thin films is, in general, surprisingly difficult, even when ZnO is grown on a ZnO substrate. However

  1. Spatial and temporal variations in the age structure of Arctic sea ice

    USGS Publications Warehouse

    Belchansky, G.I.; Douglas, D.C.; Platonov, N.G.

    2005-01-01

    Spatial and temporal variations in the age structure of Arctic sea ice are investigated using a new reverse chronology algorithm that tracks ice-covered pixels to their location and date of origin based on ice motion and concentration data. The Beaufort Gyre tends to harbor the oldest (>10 years old) sea ice in the western Arctic while direct ice advection pathways toward the Transpolar Drift Stream maintain relatively young (10 years old (10+ year age class) were observed during 1989-2003. Since the mid-1990s, losses to the 10+ year age class lacked compensation by recruitment due to a prior depletion of all mature (6-10 year) age classes. Survival of the 1994 and 1996-1998 sea ice generations reestablished most mature age classes, and thereby the potential to increase extent of the 10+ year age class during the mid-2000s.

  2. Protection of rubbers against aging with the use of structural, diffusion and kinetic effects

    SciTech Connect

    Kablov, V. F.; Zaikov, G. E.

    2014-05-15

    Processes of rubber aging in the different kinetic modes and mathematical models of the processes including aging and destruction processes under extreme conditions have been studied. The aging process for rubbers as thermodynamically open nonlinear systems has also been considered in the paper. It has been revealed that the aging process can be controlled by the internal physical-chemical processes organization and by creation of external influences (by organization of thermodynamic forces and flows). According to the Onsager principle, in certain conditions of aging the conjugation of thermodynamic forces and flows is possible. The diffusion and structural aspects of aging in elastomeric rubbers and articles thereof have been considered. The composite antiaging systems of prolonged action based on the use of microparticles with a saturated solution of the antiagers migrating into an elastomeric matrix at the exploitation have been proposed.

  3. Laws of Influence of Structural Characteristics on the Strength and Crack Resistance of Aging Metallic Materials

    NASA Astrophysics Data System (ADS)

    Nizhnik, S. B.; Usikova, G. I.

    2005-01-01

    The structural characteristics (the volume fraction, size, and shape of and the distance among hardening-phase particles) of aging alloys and steels, which define the behavior of the critical stress intensity factor during thermal hardening, are determined using the structural-mechanical approach we have developed. It is experimentally demonstrated for maraging steels that our approach is capable of proving the correlations of strength, plasticity, and crack- resistance with the structural characteristics, which were varied by changing the chemical composition of steel and thermokinetic aging conditions

  4. Dietary protein to metabolizable energy ratios on feed efficiency and structural growth of prepubertal Holstein heifers.

    PubMed

    Gabler, M T; Heinrichs, A J

    2003-01-01

    Sixty Holstein heifers, 124.5 +/- 1.1 d of age and 124.9 +/- 2.5 kg of BW, were used to evaluate the influence of dietary crude protein to metabolizable energy ratio (CP:ME) on feed efficiency, structural growth, and body condition score. Treatment rations containing a specific CP:ME ratio were assigned to heifers in a complete randomized block design with treatment periods lasting 20 wk. The CP:ME ratios were 48.3, 59.1, 67.5, and 76.5 g of CP per Mcal of ME. The CP:ME ratios were altered by adjusting the concentration of CP (12.0,15.2, 17.4, and 19.7% CP) with similar amounts of ME (2.6 Mcal/kg DM) across all treatment rations. BW was recorded weekly on two consecutive days and used to adjust dry matter intake to allow approximately 0.80 kg/d gain. Average daily gain did not differ between the treatment rations, 0.74, 0.81, 0.81, 0.77 kg/d, low to highest CP:ME ratio, respectively. Dry matter intake showed a quadratic effect for the treatment rations, 3.30, 3.41, 3.48, and 3.39 kg/d, low to highest CP:ME ratio, respectively, and averaged 2.0% BW. Feed efficiency improved linearly with increasing CP:ME ratios, 4.76, 4.42, 4.35, and 4.33, respectively. The increased CP:ME ratios were accompanied by increasing levels of plasma urea N, 9.88, 13.34, 14.94, and 16.57 mg/dl, respectively. A trend toward linear increases in wither and hip height growth resulted with increasing CP:ME. Hip width growth was quadratic with increasing CP:ME ratios. Observed linear effects in feed efficiency and some structural growth measurements demonstrate positive results when feeding CP:ME ratios >48.3 to Holstein heifers between 125 and 234 kg of BW and gaining 0.80 kg/d.

  5. Evaluation of a Crack-Growth Gage for Monitoring Possible Structural Fatigue-Crack Growth

    DTIC Science & Technology

    1978-02-01

    Reproducibility and the Lack of Dependence Upon Load Amplitude of the Gage Response 35 Al Crack Growth Rate for 2219 -T851 Aluminum 38 A2 Crack Growth Rate...for 7075- T6 Aluminum 39 A3 Crack Growth Rate for 2024-T3 Aluminum 40 vi AFML-TR-77-233 SECTION I INTRODUCTION It is well known that a fleet of...AK (in MN m ŗ/2 ) for the application of the constants are: 4.8<AKន for 2219 -T851, 6.3<AKឋ for 7075- T6 , and 5.6<AKណ for 2024-T3. Plots of the

  6. Extended Aging Theories for Predictions of Safe Operational Life of Critical Airborne Structural Components

    NASA Technical Reports Server (NTRS)

    Ko, William L.; Chen, Tony

    2006-01-01

    The previously developed Ko closed-form aging theory has been reformulated into a more compact mathematical form for easier application. A new equivalent loading theory and empirical loading theories have also been developed and incorporated into the revised Ko aging theory for the prediction of a safe operational life of airborne failure-critical structural components. The new set of aging and loading theories were applied to predict the safe number of flights for the B-52B aircraft to carry a launch vehicle, the structural life of critical components consumed by load excursion to proof load value, and the ground-sitting life of B-52B pylon failure-critical structural components. A special life prediction method was developed for the preflight predictions of operational life of failure-critical structural components of the B-52H pylon system, for which no flight data are available.

  7. Allometric Growth of Testes in Relation to Age, Body Weight and Selected Blood Parameters in Male Japanese Quail (Coturnix japonica).

    PubMed

    Vatsalya, Vatsalya; Arora, Kashmiri L

    2012-01-01

    The Japanese quail is a very valuable animal model for research in a variety of biological disciplines. The purpose of this study was to characterize and interrelate age-dependent testicular parameters with various blood constituents: blood glucose, plasma proteins and packed cell volume that are developing concurrently in the growing bird. Another objective of the study was to identify selective physioanatomical markers for predicting the testicular growth and the onset of sexual maturity. Male Japanese quail hatchlings were raised in temperature controlled brooders for up to 3 weeks of age under a constant light and then shifted to hanging cages in an air conditioned room set at ~73° F under a 14L: 10D lighting system and ad libitum access to feed and water. Starting d8, a group of 8-10 birds of uniform size and weight were selected randomly at 4-day intervals up to d52 of age for the project. The birds were weighed and blood sampled using the brachial vein and Blood Glucose (BGL), Total Plasma Proteins (PP) and Packed Cell Volume (PCV) levels were measured prior to euthanization. The testes were removed and measured for weight, length, width and Volume (VOL). All the testicular measurements were then correlated with age and body weight. The left testes were larger than the right testes and their differences were evident at d36 of age. Testicular measurements also reflected two distinct growth surges at d28, d32 and d36 of age. Combined Testes Weight (CTW) and Combined Testes Volume (CTV) revealed a strong positive correlation with PCV and PP and a negative correlation with Blood Glucose Level (BGL). Accordingly, these measurements could serve as reliable markers of growth rate and sexual maturation in male Japanese quail.

  8. Growth of tapered silica nanowires with a shallow U-shaped vapor chamber: Growth mechanism and structural and optical properties

    SciTech Connect

    Zhang, Danqing; Zhang, Xi Wei, Jianglin; Gu, Gangxu; Xiang, Gang

    2015-04-28

    Traditional chemical vapor deposition method modified with a shallow U-shaped vapor chamber has been used to synthesize tapered bamboo shoot-like (BS-like) amorphous SiO{sub 2} nanowires (NWs) on Si (100) substrates without catalyst. The key innovation of this approach lies in a creation of swirling flow of the reactant vapors during the growth, which leads to a harvest of tapered silica NWs with lengths up to several microns. The unique structures and corresponding luminescence properties of the BS-like NWs were studied and their relationship with the evaporated active reactants was explored. A thermodynamic model that considers the critical role of the vapor flow during the growth is proposed to understand the structural and optical features. The shallow U-shaped vapor chamber-aided approach may provide a viable way to tailor novel structure of NWs for potential applications in nano-devices.

  9. Breastfeeding up to two years of age or beyond and its influence on child growth and development: a systematic review.

    PubMed

    Delgado, Carlos; Matijasevich, Alicia

    2013-02-01

    A systematic review was undertaken to identify studies describing the global prevalence of breastfeeding up to two years of age or beyond and its effects on child growth and development. The MEDLINE and LILACS databases were searched without any language or date restrictions, retrieving 3,561 titles. All retrieved titles, 453 abstracts and 49 full-text articles were read. Articles with maximum breastfeeding duration of over two years were included. An analysis was carried out of 19 articles that met the inclusion criteria resulting in a combined prevalence of breastfeeding at two years of age of 33 % (95%CI: 0.23; 0.42). Increasing trends towards breastfeeding up to two years of age or beyond were observed in the past decades in South Asia. The six studies analyzing the effects of breastfeeding up to two years of age or beyond on child growth showed contradictory results. No association was found with child development. It is concluded that evidence on the medium-term effects of breastfeeding up to two years of age or beyond is scarce and contradictory. Hence, further research is needed regarding this practice.

  10. Mercury Exposure in Healthy Korean Weaning-Age Infants: Association with Growth, Feeding and Fish Intake

    PubMed Central

    Chang, Ju Young; Park, Jeong Su; Shin, Sue; Yang, Hye Ran; Moon, Jin Soo; Ko, Jae Sung

    2015-01-01

    Low-level mercury (Hg) exposure in infancy might be harmful to the physical growth as well as neurodevelopment of children. The aim of this study was to investigate postnatal Hg exposure and its relationship with anthropometry and dietary factors in late infancy. We recruited 252 healthy Korean infants between six and 24 months of age from an outpatient clinic during the 2009/2010 and 2013/2014 seasons. We measured the weight and height of the infants and collected dietary information using questionnaires. The Hg content of the hair and blood was assessed using inductively coupled plasma mass spectroscopy. The geometric mean Hg concentration in the hair and blood was 0.22 (95% confidence interval: 0.20–0.24) µg/g and 0.94 (n = 109, 95% confidence interval: 0.89–0.99) µg/L, respectively. The hair Hg concentration showed a good correlation with the blood Hg concentration (median hair-to-blood Hg ratio: 202.7, r = 0.462, p < 0.001) and was >1 µg/g in five infants. The hair Hg concentration showed significant correlations with weight gain after birth (Z-score of the weight for age—Z-score of the birthweight; r = −0.156, p = 0.015), the duration (months) of breastfeeding as the dominant method of feeding (r = 0.274, p < 0.001), and the duration of fish intake more than once per week (r = 0.138, p = 0.033). In an ordinal logistic regression analysis with categorical hair Hg content (quartiles), dietary factors, including breastfeeding as the dominant method of feeding in late infancy (cumulative odds ratio: 6.235, 95% confidence interval: 3.086–12.597, p < 0.001) and the monthly duration of fish intake more than once per week (cumulative odds ratio: 1.203, 95% confidence interval: 1.034–1.401; p = 0.017), were significantly associated with higher hair Hg content. Weight gain after birth was not, however, significantly associated with hair Hg content after adjustment for the duration of breastfeeding as the dominant method of feeding. Low-level Hg exposure

  11. Age-class structure and variability of two populations of the bluemask darter etheostoma (Doration) sp.

    USGS Publications Warehouse

    Simmons, J.W.; Layzer, J.B.; Smith, D.D.

    2008-01-01

    The bluemask darter Etheostoma (Doration) sp. is an endangered fish endemic to the upper Caney Fork system in the Cumberland River drainage in central Tennessee. Darters (Etheostoma spp.) are typically short-lived and exhibit rapid growth that quickly decreases with age. Consequently, estimating age of darters from length-frequency distributions can be difficult and subjective. We used a nonparametric kernel density estimator to reduce subjectivity in estimating ages of bluemask darters. Data were collected from a total of 2926 bluemask darters from the Collins River throughout three growing seasons. Additionally, data were collected from 842 bluemask darters from the Rocky River during one growing season. Analysis of length-frequencies indicated the presence of four age classes in both rivers. In each river, the majority of the population was comprised of fish 0.05). In both rivers, females were more abundant than males.

  12. [Age and growth of the hybrid tilapia Oreochromis niloticus x Oreochromis aureus (Perciformes: Cichlidae) in the dam "Zimapan" Mexico].

    PubMed

    Gómez-Ponce, M A; Granados-Flores, K; Padilla, C; López-Hernández, M; Núñez-Nogueira, G

    2011-06-01

    Studies on age and growth in fishes are essential to establish models on population dynamics. The previous issues were determined in this study by scale growth analyses. Between September 2003 and May 2004, 382 organisms were captured using gill and atarraya nets. Eight samples were developed every month a long this study. Standard length in centimeters (L(e)), total weight in grams (P9t)), scale length in centimeters (L(esc)) and growth rings were determined. The size and weight ranged from 38 to 232 mm (L(e)) and 8.7 to 311.9 g (P(t)), respectively. The growth rings analyses reveal four age groups, being the second group the most representative with 34.3% of the total sampled. The scale ring analyses showed two growth rings, one develops between November-January and the other between April-May, in good correlation with low temperature and gonad development, respectively. The growth parameters were established as: L infinity = 281.1mm, W infinity = 877.1g, K = 0.33 and T(0) = 0.88 year(-1). The growth curves based on length and weight were described by using the von Bertalanffy model: L(e) = 28.11[1 -e (-0.33(t+0.88))] and P(t) = 877.17[1-e (-0.33(t+0.88))]3. Finally, it is concluded that commercial catches in this dam are between a year and year and half-old when exploited.

  13. Constrained, aqueous growth of three-dimensional single crystalline zinc oxide structures

    SciTech Connect

    Pooley, Kathryn J. Joo, John H.; Hu, Evelyn L.

    2014-01-01

    We study low temperature (90 °C) aqueous growth of single crystal zinc oxide structures through patterned PMMA molds of different sizes, shapes, and orientations. We demonstrate the ability to create 3D shapes with smooth vertical sidewalls. Although the unconstrained growth is influenced by the hexagonal geometry of the underlying crystal structure, the ZnO is shown to conform exactly to any shape patterned. Using electron backscatter diffraction and scanning electron microscopy we show that the mold orientation, in conjunction with control of the growth rates of the c and m planes of the ZnO, is crucial in determining the final structure shape.

  14. Age, Growth and Reproduction of the Eastern Mudminnow (Umbra pygmaea) at the Great Swamp National Wildlife Refuge, New Jersey.

    USGS Publications Warehouse

    Panek, Frank; Weis, Judith S.

    2012-01-01

    Umbra pygmaea DeKay (Eastern Mudminnow) is one of four species of Umbridae in North America. There is little published life-history information on the species within its native range, particularly on age, growth, and reproduction. This study focuses on these aspects of the life history of this fish at the Great Swamp National Wildlife Refuge in Morris County, NJ. A total of 336 fish of seven species was collected from June 1978 through May 1979, with the Eastern Mudminnow comprising 74% of the total. The average annual growth increment in total length for the Eastern Mudminnow was 15.3 2.06 mm, with age-1 fish averaging 40 mm total length and age-5 fish, the oldest collected, averaging 107 mm total length. The length-weight relationship was log10W = -5.291 + 3.182 log10TL mm for males and log10W = -4.999 + 3.032 log10TL mm for females. We observed no statistically significant sexually dimorphic differences in length-weight relationships in this population. The ratio of females to males increased from a low of 0.6 (predominance of male fish) at age-1 to a high of 4.6 (predominance of females) at age-5. Annual mortality for age 2–5 fish ranged from 40–76% with a mean of 59 13%. Age-specific fecundity estimates ranged from 250 eggs/female at age-1 to 2168 eggs/female at age-5. The relationship of number of mature ova to age was best described by the exponential function y = 149.29e0.5287x, where y = age-specific fecundity and x = age in years. Ova ranged from 0.1–0.2 mm in diameter in June and July and averaged 1.41 0.1 mm (range = 1.29–1.62 mm) in early February prior to spawning. Peak spawning occurred in mid-April at temperatures of 9–12 °C, and all females were spent by late April (13–15 °C).

  15. Growth Differentiation Factor 11 is a Circulating Factor that Reverses Age-Related Cardiac Hypertrophy

    PubMed Central

    Loffredo, Francesco S.; Steinhauser, Matthew L.; Jay, Steven M.; Gannon, Joseph; Pancoast, James R.; Yalamanchi, Pratyusha; Sinha, Manisha; Dall’Osso, Claudia; Khong, Danika; Shadrach, Jennifer L.; Miller, Christine M.; Singer, Britta S.; Stewart, Alex; Psychogios, Nikolaos; Gerszten, Robert E.; Hartigan, Adam J.; Kim, Mi-Jeong; Serwold, Thomas; Wagers, Amy J.; Lee, Richard T.

    2013-01-01

    Summary The most common form of heart failure occurs with normal systolic function and often involves cardiac hypertrophy in the elderly. To clarify the biological mechanisms that drive cardiac hypertrophy in aging, we tested the influence of circulating factors using heterochronic parabiosis, a surgical technique in which joining of animals of different ages leads to a shared circulation. After 4 weeks of exposure to the circulation of young mice, cardiac hypertrophy in old mice dramatically regressed, accompanied by reduced cardiomyocyte size and molecular remodeling. Reversal of age-related hypertrophy was not attributable to hemodynamic or behavioral effects of parabiosis, implicating a blood-borne factor. Using modified aptamer-based proteomics, we identified the TGFβ superfamily member GDF11 as a circulating factor in young mice that declines with age. Treatment of old mice to restore GDF11 to youthful levels recapitulated the effects of parabiosis and reversed age-related hypertrophy, revealing a new therapeutic opportunity for cardiac aging. PMID:23663781

  16. Growth, population structure, and reproduction of western pond turtles (Actinemys marmorata) on the central coast of California

    USGS Publications Warehouse

    Germano, D.J.; Rathbun, G.B.

    2008-01-01

    We studied the population structure and growth of western pond turtles (Actinemys marmorata) at Vandenberg Air Force Base along the coast of central California in April 1995 and June 1996. We captured 179 individuals (115 males, 27 females) from 7 ponds during 26 days of trapping. Many turtles were adult-sized, but based on scute annuli, 74% were < 10 years of age, including many 2- to 3-year-olds. This population structure likely was due to a relatively fast growth rate, especially compared with closely related aquatic turtles in eastern North America. Mean clutch size was 5.2, but 66.7% of females were gravid, and 1 female produced 2 clutches. These reproductive