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Sample records for ageing model podospora

  1. A potential impact of DNA repair on ageing and lifespan in the ageing model organism Podospora anserina

    DEFF Research Database (Denmark)

    Soerensen, Mette; Gredilla, Ricardo; Müller-Ohldach, Mathis;

    2009-01-01

    The free radical theory of ageing states that ROS play a key role in age-related decrease in mitochondrial function via the damage of mitochondrial DNA (mtDNA), proteins and lipids. In the sexually reproducing ascomycete Podospora anserina ageing is, as in other eukaryotes, associated with mtDNA...... instability and mitochondrial dysfunction. Part of the mtDNA instabilities may arise due to accumulation of ROS induced mtDNA lesions, which, as previously suggested for mammals, may be caused by an age-related decrease in base excision repair (BER). Alignments of known BER protein sequences with the P....... anserina genome revealed high homology. We report for the first time the presence of BER activities in P. anserina mitochondrial extracts. DNA glycosylase activities decrease with age, suggesting that the increased mtDNA instability with age may be caused by decreased ability to repair mtDNA damage and...

  2. Effect of paraquat-induced oxidative stress on gene expression and aging of the filamentous ascomycete Podospora anserina

    Directory of Open Access Journals (Sweden)

    Matthias Wiemer

    2014-06-01

    Full Text Available Aging of biological systems is influenced by various factors, conditions and processes. Among others, processes allowing organisms to deal with various types of stress are of key importance. In particular, oxidative stress as the result of the generation of reactive oxygen species (ROS at the mitochondrial respiratory chain and the accumulation of ROS-induced molecular damage has been strongly linked to aging. Here we view the impact of ROS from a different angle: their role in the control of gene expression. We report a genome-wide transcriptome analysis of the fungal aging model Podospora anserina grown on medium containing paraquat (PQ. This treatment leads to an increased cellular generation and release of H2O2, a reduced growth rate, and a decrease in lifespan. The combined challenge by PQ and copper has a synergistic negative effect on growth and lifespan. The data from the transcriptome analysis of the wild type cultivated under PQ-stress and their comparison to those of a longitudinal aging study as well as of a copper-uptake longevity mutant of P. anserina revealed that PQ-stress leads to the up-regulation of transcripts coding for components involved in mitochondrial remodeling. PQ also affects the expression of copper-regulated genes suggesting an increase of cytoplasmic copper levels as it has been demonstrated earlier to occur during aging of P. anserina and during senescence of human fibroblasts. This effect may result from the induction of the mitochondrial permeability transition pore via PQ-induced ROS, leading to programmed cell death as part of an evolutionary conserved mechanism involved in biological aging and lifespan control.

  3. Calorie restriction causes healthy life span extension in the filamentous fungus Podospora anserina

    NARCIS (Netherlands)

    Diepeningen, van A.D.; Maas, M.F.P.M.; Huberts, D.H.E.W.; Goedbloed, D.J.; Engelmoer, D.J.P.; Slakhorst, S.M.; Koopmanschap, A.B.; Krause, F.; Dencher, N.A.; Sellem, C.H.; Sainsard-Chanet, A.; Hoekstra, R.F.; Debets, A.J.M.

    2010-01-01

    Although most fungi appear to be immortal, some show systemic senescence within a distinct time frame. Podospora anserina for example shows an irreversible growth arrest within weeks of culturing associated with a destabilization of the mitochondrial genome. Here, we show that calorie restriction (C

  4. Mathematical Model of Age Aggression

    OpenAIRE

    Golovinski, P. A.

    2013-01-01

    We formulate a mathematical model of competition for resources between representatives of different age groups. A nonlinear kinetic integral-differential equation of the age aggression describes the process of redistribution of resources. It is shown that the equation of the age aggression has a stationary solution, in the absence of age-dependency in the interaction of different age groups. A numerical simulation of the evolution of resources for different initial distributions has done. It ...

  5. Mitochondrial pAL2-1 plasmid homologs are senescence factors in Podospora anserina independent of intrinsic senescence

    NARCIS (Netherlands)

    van Diepeningen, Anne D; Debets, Alfons J M; Slakhorst, S Marijke; Hoekstra, Rolf F

    2008-01-01

    Since the first description of a linear mitochondrial plasmid in Podospora anserina, pAL2-1, and homologous plasmids have gone from being considered beneficial longevity plasmids, via neutral genetic elements, toward mutator plasmids causing senescence. The plasmid has an invertron structure, with t

  6. Pavement Aging Model by Response Surface Modeling

    Directory of Open Access Journals (Sweden)

    Manzano-Ramírez A.

    2011-10-01

    Full Text Available In this work, surface course aging was modeled by Response Surface Methodology (RSM. The Marshall specimens were placed in a conventional oven for time and temperature conditions established on the basis of the environment factors of the region where the surface course is constructed by AC-20 from the Ing. Antonio M. Amor refinery. Volatilized material (VM, load resistance increment (ΔL and flow resistance increment (ΔF models were developed by the RSM. Cylindrical specimens with real aging were extracted from the surface course pilot to evaluate the error of the models. The VM model was adequate, in contrast (ΔL and (ΔF models were almost adequate with an error of 20 %, that was associated with the other environmental factors, which were not considered at the beginning of the research.

  7. Identification of a Hypothetical Protein from Podospora anserina as a Nitroalkane Oxidase

    Energy Technology Data Exchange (ETDEWEB)

    Tormos, Jose R.; Taylor, Alexander B.; Daubner, S. Colette; Hart, P. John; Fitzpatrick, Paul F. (Texas-HSC); (St. Mary)

    2010-08-23

    The flavoprotein nitroalkane oxidase (NAO) from Fusarium oxysporum catalyzes the oxidation of primary and secondary nitroalkanes to their respective aldehydes and ketones. Structurally, the enzyme is a member of the acyl-CoA dehydrogenase superfamily. To date no enzymes other than that from F. oxysporum have been annotated as NAOs. To identify additional potential NAOs, the available database was searched for enzymes in which the active site residues Asp402, Arg409, and Ser276 were conserved. Of the several fungal enzymes identified in this fashion, PODANSg2158 from Podospora anserina was selected for expression and characterization. The recombinant enzyme is a flavoprotein with activity on nitroalkanes comparable to the F. oxysporum NAO, although the substrate specificity is somewhat different. Asp399, Arg406, and Ser273 in PODANSg2158 correspond to the active site triad in F. oxysporum NAO. The k{sub cat}/K{sub M}-pH profile with nitroethane shows a pK{sub a} of 5.9 that is assigned to Asp399 as the active site base. Mutation of Asp399 to asparagine decreases the k{sub cat}/K{sub M} value for nitroethane over 2 orders of magnitude. The R406K and S373A mutations decrease this kinetic parameter by 64- and 3-fold, respectively. The structure of PODANSg2158 has been determined at a resolution of 2.0 {angstrom}, confirming its identification as an NAO.

  8. Natural variation of heterokaryon incompatibility gene het-c in Podospora anserina reveals diversifying selection.

    Science.gov (United States)

    Bastiaans, Eric; Debets, Alfons J M; Aanen, Duur K; van Diepeningen, Anne D; Saupe, Sven J; Paoletti, Mathieu

    2014-04-01

    In filamentous fungi, allorecognition takes the form of heterokaryon incompatibility, a cell death reaction triggered when genetically distinct hyphae fuse. Heterokaryon incompatibility is controlled by specific loci termed het-loci. In this article, we analyzed the natural variation in one such fungal allorecognition determinant, the het-c heterokaryon incompatibility locus of the filamentous ascomycete Podospora anserina. The het-c locus determines an allogenic incompatibility reaction together with two unlinked loci termed het-d and het-e. Each het-c allele is incompatible with a specific subset of the het-d and het-e alleles. We analyzed variability at the het-c locus in a population of 110 individuals, and in additional isolates from various localities. We identified a total of 11 het-c alleles, which define 7 distinct incompatibility specificity classes in combination with the known het-d and het-e alleles. We found that the het-c allorecognition gene of P. anserina is under diversifying selection. We find a highly unequal allele distribution of het-c in the population, which contrasts with the more balanced distribution of functional groups of het-c based on their allorecognition function. One explanation for the observed het-c diversity in the population is its function in allorecognition. However, alleles that are most efficient in allorecognition are rare. An alternative and not exclusive explanation for the observed diversity is that het-c is involved in pathogen recognition. In Arabidopsis thaliana, a homolog of het-c is a pathogen effector target, supporting this hypothesis. We hypothesize that the het-c diversity in P. anserina results from both its functions in pathogen-defense, and allorecognition. PMID:24448643

  9. A unique CE16 acetyl esterase from Podospora anserina active on polymeric xylan.

    Science.gov (United States)

    Puchart, Vladimír; Berrin, Jean-Guy; Haon, Mireille; Biely, Peter

    2015-12-01

    The genome of the coprophilous fungus Podospora anserina displays an impressive array of genes encoding hemicellulolytic enzymes. In this study, we focused on a putative carbohydrate esterase (CE) from family 16 (CE16) that bears a carbohydrate-binding module from family CBM1. The protein was heterologously expressed in Pichia pastoris and purified to electrophoretic homogeneity. The P. anserina CE16 enzyme (PaCE16A) exhibited different catalytic properties than so far known CE16 esterases represented by the Trichoderma reesei CE16 acetyl esterase (TrCE16). A common property of both CE16 esterases is their exodeacetylase activity, i.e., deesterification at positions 3 and 4 of monomeric xylosides and the nonreducing end xylopyranosyl (Xylp) residue of oligomeric homologues. However, the PaCE16A showed lower positional specificity than TrCE16 and efficiently deacetylated also position 2. The major difference observed between PaCE16A and TrCE16 was found on polymeric substrate, acetylglucuronoxylan. While TrCE16 does not attack internal acetyl groups, PaCE16A deacetylated singly and doubly acetylated Xylp residues in the polymer to such an extent that it resulted in the polymer precipitation. Similarly as typical acetylxylan esterases belonging to CE1, CE4, CE5, and CE6 families, PaCE16A did not attack 3-O-acetyl group of xylopyranosyl residues carrying 4-O-methyl-D-glucuronic acid at position 2. PaCE16A thus represents a CE16 member displaying unique catalytic properties, which are intermediate between the TrCE16 exodeacetylase and acetylxylan esterases designed to deacetylate polymeric substrate. The catalytic versatility of PaCE16A makes the enzyme an important candidate for biotechnological applications. PMID:26329850

  10. The PaPsr1 and PaWhi2 genes are members of the regulatory network that connect stationary phase to mycelium differentiation and reproduction in Podospora anserina.

    Science.gov (United States)

    Timpano, Hélène; Chan Ho Tong, Laetitia; Gautier, Valérie; Lalucque, Hervé; Silar, Philippe

    2016-09-01

    In filamentous fungi, entrance into stationary phase is complex as it is accompanied by several differentiation and developmental processes, including the synthesis of pigments, aerial hyphae, anastomoses and sporophores. The regulatory networks that control these processes are still incompletely known. The analysis of the "Impaired in the development of Crippled Growth (IDC)" mutants of the model filamentous ascomycete Podospora anserina has already yielded important information regarding the pathway regulating entrance into stationary phase. Here, the genes affected in two additional IDC mutants are identified as orthologues of the Saccharomyces cerevisiae WHI2 and PSR1 genes, known to regulate stationary phase in this yeast, arguing for a conserved role of these proteins throughout the evolution of ascomycetes. PMID:27353975

  11. Aging Successfully: A Four-Factor Model

    Science.gov (United States)

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

    2011-01-01

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

  12. Aging Models of Acute Seizures and Epilepsy

    OpenAIRE

    Kelly, Kevin M.

    2010-01-01

    Aged animals have been used by researchers to better understand the differences between the young and the aged brain and how these differences may provide insight into the mechanisms of acute seizures and epilepsy in the elderly. To date, there have been relatively few studies dedicated to the modeling of acute seizures and epilepsy in aged, healthy animals. Inherent challenges to this area of research include the costs associated with the purchase and maintenance of older animals and, at tim...

  13. Animal models of age related macular degeneration

    OpenAIRE

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

    2012-01-01

    Age related macular degeneration (AMD) is the leading cause of vision loss of those over the age of 65 in the industrialized world. The prevalence and need to develop effective treatments for AMD has lead to the development of multiple animal models. AMD is a complex and heterogeneous disease that involves the interaction of both genetic and environmental factors with the unique anatomy of the human macula. Models in mice, rats, rabbits, pigs and non-human primates have recreated many of the ...

  14. A Model of Spirituality for Ageing Muslims.

    Science.gov (United States)

    Ahmad, Mahjabeen; Khan, Shamsul

    2016-06-01

    Spirituality's influence on general well-being and its association with healthy ageing has been studied extensively. However, a different perspective has to be brought in when dealing with spirituality issues of ageing Muslims. Central to this perspective is the intertwining of religion and spirituality in Islam. This article will contribute to the understanding of the nature of Islamic spirituality and its immense importance in the life of a practicing ageing Muslim. Consequently, it will help care providers to include appropriate spiritual care in the care repertoire of a Muslim care recipient. It is assumed that the framework for a model of spirituality based on Islamic religious beliefs would help contextualise the relationship between spirituality and ageing Muslims. Not only challenges, but also the opportunities that old age provides for charting the spiritual journey have underpinned this model. PMID:25822881

  15. Rodent models of aging bone: an update.

    Science.gov (United States)

    Syed, Farhan A; Melim, Terry

    2011-12-01

    With an increase in the average life span especially in the Western hemisphere, there is renewed interest in treating maladies of old age including osteoporosis. Age-related bone loss and resultant osteoporosis substantially increase risk of fractures and morbidity in the geriatric population leading to both a decline in the quality of life for the elderly as well as a substantial burden on the health care system. Herein, we review recent research in murine and rodent models looking at how both extrinsic and intrinsic factors such as hormones, biochemicals, neuromodulators, inflammatory cytokines, oxidative stress, nutrition, and exercise influence the skeleton with age. Recent studies on the relationship between bone and fat in the marrow, and the fate of the marrow mesenchymal stromal cell population, which can give rise to either bone-forming osteoblasts or fat-forming adipocytic cells as a function of age, have also been highlighted. An appreciable range of studies using aging murine as well as cellular models are discussed, as these studies have broadened our understanding of the pathways and players in the aging bone. Impactful information regarding aging and the bone may then allow the application of better pharmacologic as well as nonpharmacologic regimens to alleviate bone loss due to aging. PMID:21918858

  16. Pathology of Mouse Models of Accelerated Aging.

    Science.gov (United States)

    Harkema, L; Youssef, S A; de Bruin, A

    2016-03-01

    Progeroid mouse models display phenotypes in multiple organ systems that suggest premature aging and resemble features of natural aging of both mice and humans. The prospect of a significant increase in the global elderly population within the next decades has led to the emergence of "geroscience," which aims at elucidating the molecular mechanisms involved in aging. Progeroid mouse models are frequently used in geroscience as they provide insight into the molecular mechanisms that are involved in the highly complex process of natural aging. This review provides an overview of the most commonly reported nonneoplastic macroscopic and microscopic pathologic findings in progeroid mouse models (eg, osteoporosis, osteoarthritis, degenerative joint disease, intervertebral disc degeneration, kyphosis, sarcopenia, cutaneous atrophy, wound healing, hair loss, alopecia, lymphoid atrophy, cataract, corneal endothelial dystrophy, retinal degenerative diseases, and vascular remodeling). Furthermore, several shortcomings in pathologic analysis and descriptions of these models are discussed. Progeroid mouse models are valuable models for aging, but thorough knowledge of both the mouse strain background and the progeria-related phenotype is required to guide interpretation and translation of the pathology data. PMID:26864891

  17. A model for two-step ageing

    Indian Academy of Sciences (India)

    K T Kashyap; C Ramachandra; B Chatterji; S Lele

    2000-10-01

    In commercial practice, two-step ageing is commonly used in Al–Zn–Mg alloys to produce a fine dispersion of ′ precipitates to accentuate the mechanical properties and resistance to stress corrosion cracking. While this is true in Al–Zn–Mg alloys, two-step ageing leads to inferior properties in Al–Mg–Si alloys. This controversial behaviour in different alloys can be explained by Pashley’s Kinetic model. Pashley’s model addresses the stability of clusters after two-step ageing. In the development of the model, the surface energy term between cluster and matrix is taken into account while the coherency strains between the cluster and matrix are not considered. In the present work, a model is developed which takes into account the coherency strains between cluster and matrix and defines a new stability criterion, inclusive of strain energy term. Experiments were done on AA 7010 aluminium alloy by carrying out a two-step ageing treatment and the results fit the new stability criterion. Thus it is found that the new model for two-step ageing is verified in the case of Al–Zn–Mg alloy.

  18. A CONTINUUM DAMAGE MODEL OF AGING CONCRETE

    Institute of Scientific and Technical Information of China (English)

    Zhao Zhenyang; Xie Huicai; Xu Tao; Yu Jie; Cai Changan

    2001-01-01

    There is up to now no constitutive model in the current theories of CDM that could give a description for the degradation of aging concrete. The two internal state variables β and ω are introduced in this paper. β is called cohesion variable as an additional kinematic parameter, reflecting the cohesion state among material particles. ω is called damage factor for micro-defects such as voids.Then a damage model and a series of constitutive equations are developed on Continuum Mechanics.The model proposed could give a valid description for the whole-course-degradation of aging concrete due tochemical and mechanical actions. Finally, the validity of the model is evaluated by an example and experimental results.

  19. An age structured demographic model of technology

    CERN Document Server

    Mercure, J -F

    2013-01-01

    At the heart of technology transitions lie complex processes of technology choices. Understanding and planning sustainability transitions requires modelling work, which necessitates a theory of technology substitution. A theoretical model of technological change and turnover is presented, intended as a methodological paradigm shift from widely used conventional modelling approaches such as cost optimisation. It follows the tradition of evolutionary economics and evolutionary game theory, using ecological population growth dynamics to represent the evolution of technology populations in the marketplace, with substitutions taking place at the level of the decision-maker. Extended to use principles of human demography or the age structured evolution of species in interacting ecosystems, this theory is built from first principles, and through an appropriate approximation, reduces to a form identical to empirical models of technology diffusion common in the technology transitions literature. Using an age structure...

  20. Mathematical Modelling of Metabolic Regulation in Aging

    Directory of Open Access Journals (Sweden)

    Mark T. Mc Auley

    2015-04-01

    Full Text Available The underlying cellular mechanisms that characterize aging are complex and multifaceted. However, it is emerging that aging could be regulated by two distinct metabolic hubs. These hubs are the pathway defined by the mammalian target of rapamycin (mTOR and that defined by the NAD+-dependent deacetylase enzyme, SIRT1. Recent experimental evidence suggests that there is crosstalk between these two important pathways; however, the mechanisms underpinning their interaction(s remains poorly understood. In this review, we propose using computational modelling in tandem with experimentation to delineate the mechanism(s. We briefly discuss the main modelling frameworks that could be used to disentangle this relationship and present a reduced reaction pathway that could be modelled. We conclude by outlining the limitations of computational modelling and by discussing opportunities for future progress in this area.

  1. Hydra, a powerful model for aging studies

    Science.gov (United States)

    Tomczyk, Szymon; Fischer, Kathleen; Austad, Steven; Galliot, Brigitte

    2015-01-01

    Cnidarian Hydra polyps escape senescence, most likely due to the robust activity of their three stem cell populations. These stem cells continuously self-renew in the body column and differentiate at the extremities following a tightly coordinated spatial pattern. Paul Brien showed in 1953 that in one particular species, Hydra oligactis, cold-dependent sexual differentiation leads to rapid aging and death. Here, we review the features of this inducible aging phenotype. These cellular alterations, detected several weeks after aging was induced, are characterized by a decreasing density of somatic interstitial cell derivatives, a disorganization of the apical nervous system, and a disorganization of myofibers of the epithelial cells. Consequently, tissue replacement required to maintain homeostasis, feeding behavior, and contractility of the animal are dramatically affected. Interestingly, this aging phenotype is not observed in all H. oligactis strains, thus providing a powerful experimental model for investigations of the genetic control of aging. Given the presence in the cnidarian genome of a large number of human orthologs that have been lost in ecdysozoans, such approaches might help uncover novel regulators of aging in vertebrates. PMID:26120246

  2. Centenarians - a useful model for healthy aging?

    DEFF Research Database (Denmark)

    Engberg, Henriette; Oksuzyan, Anna; Jeune, Bernard;

    2009-01-01

    Centenarians surpass the current human life expectancy with about 20-25 years. However, whether centenarians represent healthy aging still remains an open question. Previous studies have been hampered by a number of methodological shortcomings such as a cross-sectional design and lack of an...... appropriate control group. In a longitudinal population-based cohort, it was examined whether the centenarian phenotype may be a useful model for healthy aging. The study was based on a completefollow up of 39 945 individuals alive in the Danish 1905 birth cohort on January 1, 1977 identified through the...... 68.4% among individuals who died in their early 80s. This trend was evident in both sexes. As a result of their lower hospitalization rates and length of stay in hospital compared with their contemporaries, who died at younger ages, Danish centenarians represent healthy agers. Centenarians constitute...

  3. A life span model of successful aging.

    Science.gov (United States)

    Schulz, R; Heckhausen, J

    1996-07-01

    To lay the foundation for our model, we first describe existing conceptions of successful aging, underlying assumptions of development, and criteria for success. The model presented extends the discourse on this topic in three directions: (a) It frames the discussion of successful aging in the broader context of life course development; (b) it accounts for both normative and nonnormative (i.e., exceptional) success; and (c) it integrates motivational processes into a theory of successful aging. Successful aging is equated with the development and maintenance of primary control throughout the life course, which is achieved through control-related processes that optimize selection and failure compensation functions. Selection processes regulate the choice of action goals so that diversity is maintained and positive and negative trade-offs between performance domains and life stages are taken into account. Compensation mechanisms serve to maintain, enhance, and remediate competencies and motivational resources after failure experiences. Both compensation and selection processes are motivated by desires for primary control and can be characterized in terms of primary and secondary control processes. PMID:8694390

  4. Are invertebrates relevant models in ageing research?

    DEFF Research Database (Denmark)

    Hansen, Benni Winding; Vang, Ole; Erdogan, Cihan Suleyman

    2016-01-01

    evolutionary conserved key protein kinase in the TOR pathway that regulates growth, proliferation and cell metabolism in response to nutrients, growth factors and stress. Comparing the ageing process in invertebrate model organisms with relatively short lifespan with mammals provides valuable information about...... the molecular mechanisms underlying the ageing process faster than mammal systems. Inhibition of the TOR pathway activity via either genetic manipulation or rapamycin increases lifespan profoundly in most invertebrate model organisms. This contribution will review the recent findings in invertebrates...... concerning the TOR pathway and effects of TOR inhibition by rapamycin on lifespan. Besides some contradictory results, the majority points out that rapamycin induces longevity. This suggests that administration of rapamycin in invertebrates is a promising tool for pursuing the scientific puzzle of lifespan...

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

    Science.gov (United States)

    Joulan, Karine; Brémond, Roland

    2015-01-01

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

  6. Spatial age-length key modelling using continuation ratio logits

    DEFF Research Database (Denmark)

    Berg, Casper W.; Kristensen, Kasper

    -called age-length key (ALK) is then used to obtain the age distribution. Regional differences in ALKs are not uncommon, but stratification is often problematic due to a small number of samples. Here, we combine generalized additive modelling with continuation ratio logits to model the probability of age...

  7. Snow water equivalent modeling components in NewAge-JGrass

    OpenAIRE

    G. Formetta; S. K. Kampf; David, O.; R. Rigon

    2014-01-01

    This paper presents a package of modified temperature-index-based snow water equivalent models as part of the hydrological modeling system NewAge-JGrass. Three temperature-based snow models are integrated into the NewAge-JGrass modeling system and use many of its components such as those for radiation balance (short wave radiation balance, SWRB), kriging (KRIGING), automatic calibration algorithms (particle swarm optimization) and tests of goodness of fit (NewAge-V), to buil...

  8. Efficacy of Female Rat Models in Translational Cardiovascular Aging Research

    OpenAIRE

    Rice, K.M.; J. C. Fannin; Gillette, C.; E. R. Blough

    2014-01-01

    Cardiovascular disease is the leading cause of death in women in the United States. Aging is a primary risk factor for the development of cardiovascular disease as well as cardiovascular-related morbidity and mortality. Aging is a universal process that all humans undergo; however, research in aging is limited by cost and time constraints. Therefore, most research in aging has been done in primates and rodents; however it is unknown how well the effects of aging in rat models translate into h...

  9. Ageing behaviour of electrochemical double layer capacitors. Part I. Experimental study and ageing model

    Energy Technology Data Exchange (ETDEWEB)

    Bohlen, Oliver; Kowal, Julia; Sauer, Dirk Uwe [Institute for Power Electronics and Electrical Drives ISEA, RWTH Aachen University, Aachen (Germany)

    2007-10-11

    Different types of commercially available electrochemical double layer capacitors (EDLCs) were analysed in accelerated ageing tests by impedance spectroscopy. From these measurements the parameters of an impedance model were determined. The characteristic change of the impedance parameters is discussed and an ageing model for EDLCs is developed. (author)

  10. Monitoring and modeling the aging mechanisms

    International Nuclear Information System (INIS)

    origin of these cracks might be caused by differential drying shrinkage for the cracks near the raft and by deviated post-tensioning near the material hatch. The bi-directional prestress limits the cracks opening when the containment is over-pressurized. However, under sustained loads, concrete creep leads to a loss of prestress due to the deformation compatibility between the grouted tendons the concrete mass. Thus the safety margin shall be affected since cracks opening may become larger with time. In order to optimize the extent of reparation, it is therefore compulsory to improve the prediction of the long-time mechanical behavior of the containment. This task requires: - the improvement of the delayed behavior understanding, the so-called aging mechanism, the development of realistic, i.e. less conservative, models specifically designed for the very specific loading conditions of the inner containment; - the integration of monitored data in the numerical or analytical simulation; - the evaluation of the impact of the concrete damage and the loss of prestress on the hydraulic behavior. The paper addresses the following items: inner containment description and in-situ monitoring; concrete shrinkage and creep modeling; laboratory testing; numerical computation and comparison with monitored data; introducing monitored data in the computation; impact of damage on the leak tightness of the containment wall. The communication illustrates the general strategy adopted by EDF in order to assess the long-term integrity of NPP inner concrete containment vessel. All analysis and computation are performed on the standard zone of the concrete vessel. On-going research and development programs are focused on the refinement of the methodology and their application to more realistic numerical model of large-scale structure

  11. Virtual age model for equipment aging plant based on operation environment and service state

    International Nuclear Information System (INIS)

    The accelerated life model based on the operation environment and service state was established by taking the virtual age as the equipment aging indices. The effect of different operation environments and service states on the reliability and virtual age under the continuum operation conditions and cycle operation conditions were analyzed, and the sensitivities of virtual age on operational environments and service states were studied. The results of the example application show that the effect of NPP equipment lifetime and the key parameters related to the reliability can be quantified by this model, and the result is in accordance with the reality.(authors)

  12. Chapter 6. Models of groundwater ages and residence times

    International Nuclear Information System (INIS)

    CFC ages are generally based on absolute concentrations. As a result, when waters of different ages mix, the CFC concentration changes and so does the apparent age. Because CFC concentrations in the atmosphere are not a linear function of time, the apparent age is not necessarily proportional to the fraction of each component of water in the mixture. In this chapter, more general models of groundwater age distributions in simple aquifer types are reviewed, as well as how the age distribution relates to aquifer properties

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-03-01

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

  15. Senescence vs. sustenance: Evolutionary-demographic models of aging

    OpenAIRE

    Annette Baudisch; James Vaupel

    2010-01-01

    Humans, and many other species, suffer senescence: mortality increases and fertility declines with adult age. Some species, however, enjoy sustenance: mortality and fertility remain constant. Here we develop simple but general evolutionary-demographic models to explain the conditions that favor senescence vs. sustenance. The models illustrate how mathematical demography can deepen understanding of the evolution of aging.

  16. Stability analysis for a general age-dependent vaccination model

    International Nuclear Information System (INIS)

    An SIR epidemic model of a general age-dependent vaccination model is investigated when the fertility, mortality and removal rates depends on age. We give threshold criteria of the existence of equilibriums and perform stability analysis. Furthermore a critical vaccination coverage that is sufficient to eradicate the disease is determined. (author). 12 refs

  17. Successful aging as a continuum of functional independence: lessons from physical disability models of aging.

    NARCIS (Netherlands)

    Lowry, K.A.; Vallejo, A.N.; Studenski, S.A.

    2012-01-01

    Successful aging is a multidimensional construct that could be viewed as a continuum of achievement. Based on the disability model proposed by the WHO International Classification of Functioning, Disability and Health, successful aging includes not only the presence or absence of disease, but also a

  18. An integrated modeling approach to age invariant face recognition

    Science.gov (United States)

    Alvi, Fahad Bashir; Pears, Russel

    2015-03-01

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

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

    Science.gov (United States)

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

    2016-09-01

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

  20. A comprehensive approach to age-dependent dosimetric modeling

    International Nuclear Information System (INIS)

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

  1. An age structured model for obesity prevalence dynamics in populations

    Directory of Open Access Journals (Sweden)

    Gilberto González Parra

    2010-08-01

    Full Text Available Objective. Modeling the correlation of the development of obesity in a population with age and time and predict the dynamics of the correlation of the development of obesity in a population with age and time under different scenarios in Valencia (Spain. Materials and methods. An age structured mathematical model is used to describe the future dynamics of obesity prevalence for different ages in human population with excess weight. Simulation of the model with parameters estimated using the Health Survey of the Region of Valencia 2000 (4.319 interviews and Health Survey of the Region of Valencia 2005 (4.012 interviews. The model considers only overweight and obese populations since these subpopulations are the most relevant on obesity health concern. Results. The model allows predicting and studying the prevalence of obesity for each age. Results showed an increasing trend of obesity in the following years in well accordance with the trend observed in several countries. Conclusions. Based on the numerical simulations it is possible to conclude that the age structured mathematical model is suitable to forecast the obesity epidemic in each age group in different countries. Additionally, this type of models may be applied to study other characteristics of other populations such animal populations.

  2. 14C-age tracers in global ocean circulation models

    Science.gov (United States)

    Koeve, W.; Wagner, H.; Kähler, P.; Oschlies, A.

    2015-07-01

    The natural abundance of 14C in total CO2 dissolved in seawater (DIC) is a property applied to evaluate the water age structure and circulation in the ocean and in ocean models. In this study we use three different representations of the global ocean circulation augmented with a suite of idealised tracers to study the potential and limitations of using natural 14C to determine water age, which is the time elapsed since a body of water has been in contact with the atmosphere. We find that, globally, bulk 14C-age is dominated by two equally important components, one associated with ageing, i.e. the time component of circulation, and one associated with a "preformed 14C-age". The latter quantity exists because of the slow and incomplete atmosphere-ocean equilibration of 14C particularly in high latitudes where many water masses form. In the ocean's interior, preformed 14C-age behaves like a passive tracer. The relative contribution of the preformed component to bulk 14C-age varies regionally within a given model, but also between models. Regional variability in the Atlantic Ocean is associated with the mixing of waters with very different end members of preformed 14C-age. Here, variations in the preformed component over space and time mask the circulation component to an extent that its patterns are not detectable from bulk 14C-age. Between models, the variability of preformed 14C-age can also be considerable (factor of 2), related to the combination of physical model parameters, which influence circulation dynamics or gas exchange. The preformed component was found to be very sensitive to gas exchange and moderately sensitive to ice cover. In our model evaluation, the choice of the gas-exchange constant from within the currently accepted range of uncertainty had such a strong influence on preformed and bulk 14C-age that if model evaluation would be based on bulk 14C-age, it could easily impair the evaluation and tuning of a model's circulation on global and regional

  3. The heuristic value of redundancy models of aging

    NARCIS (Netherlands)

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

    2015-01-01

    Molecular studies of aging aim to unravel the cause(s) of aging bottom-up, but linking these mechanisms to organismal level processes remains a challenge. We propose that complementary top-down data-directed modelling of organismal level empirical findings may contribute to developing these links. T

  4. Multiscale Concrete Modeling of Aging Degradation

    Energy Technology Data Exchange (ETDEWEB)

    Hammi, Yousseff [Mississippi State Univ., Mississippi State, MS (United States); Gullett, Philipp [Mississippi State Univ., Mississippi State, MS (United States); Horstemeyer, Mark F. [Mississippi State Univ., Mississippi State, MS (United States)

    2015-07-31

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

  5. Bayesian Age-Period-Cohort Modeling and Prediction - BAMP

    Directory of Open Access Journals (Sweden)

    Volker J. Schmid

    2007-10-01

    Full Text Available The software package BAMP provides a method of analyzing incidence or mortality data on the Lexis diagram, using a Bayesian version of an age-period-cohort model. A hierarchical model is assumed with a binomial model in the first-stage. As smoothing priors for the age, period and cohort parameters random walks of first and second order, with and without an additional unstructured component are available. Unstructured heterogeneity can also be included in the model. In order to evaluate the model fit, posterior deviance, DIC and predictive deviances are computed. By projecting the random walk prior into the future, future death rates can be predicted.

  6. 14C-age tracers in global ocean circulation models

    Directory of Open Access Journals (Sweden)

    W. Koeve

    2014-10-01

    Full Text Available The natural abundance of 14C in total CO2 dissolved in seawater is a property applied to evaluate the water age structure and circulation in the ocean and in ocean models. In this study we use three different representations of the global ocean circulation augmented with a suite of idealised tracers to study the potential and limitations of using natural 14C to determine water age, the time elapsed since a body of water had contact with the atmosphere. We find that, globally, bulk 14C-age is dominated by two equally important components, one associated with aging, i.e. the time component of circulation and one associated with a "preformed 14C-age". This latter quantity exists because of the slow and incomplete atmosphere/ocean equilibration of 14C in particular in high latitudes where many water masses form. The relative contribution of the preformed component to bulk 14C-age varies regionally within a given model, but also between models. Regional variability, e.g. in the Atlantic Ocean is associated with the mixing of waters with very different end members of preformed 14C-age. In the Atlantic, variations in the preformed component over space and time mask the circulation component to an extent that its patterns are not detectable from bulk 14C-age alone. Between models the variability of age can also be considerable (factor of 2, related to the combinations of physical model parameters, which influence circulation dynamics, and gas exchange in the models. The preformed component was found to be very sensitive to gas exchange and moderately sensitive to ice cover. In our model evaluation exercise, the choice of the gas exchange constant from within the current range of uncertainty had such a strong influence on preformed and bulk 14C-age that if model evaluation would be based on bulk 14C-age it could easily impair the evaluation and tuning of a models circulation on global and regional scales. Based on the results of this study, we propose

  7. Aging mechanism in model Pickering emulsion

    Science.gov (United States)

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

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

  8. Age dependencies in the modelling of radiation carcinogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Kellerer, A.M. (Munich Univ. (Germany). Radiobiological Inst. GSF, Neuherberg (Germany). Inst. for Radiation Protection); Barclay, D. (GSF, Neuherberg (Germany). Inst. for Radiation Protection)

    1992-01-01

    Models for the dose and age dependence of radiation induced cancer have been based primarily on the follow-up of the atomic bomb survivors. Two different concepts have been deduced for leukaemias and for other cancers. The excess leukaemias appear in a distinct temporal wave with a maximum 5 to 10 years after radiation exposure; the distribution is more narrow for younger ages, but there is little dependence of the total attributable risk on age at exposure. For other cancers the latent periods are longer and, according to the current interpretation, the excess rates are then proportional to the age specific spontaneous rates, so that most excess cases would arise at old age. The factors of proportionality, and thus the attributable risks, are assumed to be markedly higher for young ages at exposure. It is argued here, that there is no firm support for this interpretation. (author).

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

    Science.gov (United States)

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

    2016-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Ming-Ming Lai

    2016-01-01

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

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

    Science.gov (United States)

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

    2016-01-01

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

  12. Degradation modeling with application to aging and maintenance effectiveness evaluations

    International Nuclear Information System (INIS)

    This paper describes a modeling approach to analyze component degradation and failure data to understand the aging process of components. As used here, degradation modeling is the analysis of information on component degradation in order to develop models of the process and its implications. This particular modeling focuses on the analysis of the times of component degradations, to model how the rate of degradation changes with the age of the component. The methodology presented also discusses the effectiveness of maintenance as applicable to aging evaluations. The specific applications which are performed show quantitative models of component degradation rates and component failure rates from plant-specific data. The statistical techniques which are developed and applied allow aging trends to be effectively identified in the degradation data, and in the failure data. Initial estimates of the effectiveness of maintenance in limiting degradations from becoming failures also are developed. These results are important first steps in degradation modeling, and show that degradation can be modeled to identify aging trends. 2 refs., 8 figs

  13. The heuristic value of redundancy models of aging.

    Science.gov (United States)

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

    2015-11-01

    Molecular studies of aging aim to unravel the cause(s) of aging bottom-up, but linking these mechanisms to organismal level processes remains a challenge. We propose that complementary top-down data-directed modelling of organismal level empirical findings may contribute to developing these links. To this end, we explore the heuristic value of redundancy models of aging to develop a deeper insight into the mechanisms causing variation in senescence and lifespan. We start by showing (i) how different redundancy model parameters affect projected aging and mortality, and (ii) how variation in redundancy model parameters relates to variation in parameters of the Gompertz equation. Lifestyle changes or medical interventions during life can modify mortality rate, and we investigate (iii) how interventions that change specific redundancy parameters within the model affect subsequent mortality and actuarial senescence. Lastly, as an example of data-directed modelling and the insights that can be gained from this, (iv) we fit a redundancy model to mortality patterns observed by Mair et al. (2003; Science 301: 1731-1733) in Drosophila that were subjected to dietary restriction and temperature manipulations. Mair et al. found that dietary restriction instantaneously reduced mortality rate without affecting aging, while temperature manipulations had more transient effects on mortality rate and did affect aging. We show that after adjusting model parameters the redundancy model describes both effects well, and a comparison of the parameter values yields a deeper insight in the mechanisms causing these contrasting effects. We see replacement of the redundancy model parameters by more detailed sub-models of these parameters as a next step in linking demographic patterns to underlying molecular mechanisms. PMID:26362219

  14. Deletion of the MED13 and CDK8 subunits of the Mediator improves the phenotype of a long-lived respiratory deficient mutant of Podospora anserina.

    Science.gov (United States)

    Humbert, Adeline; Bovier, Elodie; Sellem, Carole H; Sainsard-Chanet, Annie

    2015-09-01

    In Podospora anserina, the loss of function of the cytochrome segment of the mitochondrial respiratory chain is viable. This is due to the presence in this organism, as in most filamentous fungi, of an alternative respiratory oxidase (AOX) that provides a bypass to the cytochrome pathway. However mutants lacking a functional cytochrome pathway present multiple phenotypes including poorly colored thin mycelium and slow growth. In a large genetic screen based on the improvement of these phenotypes, we isolated a large number of independent suppressor mutations. Most of them led to the constitutive overexpression of the aox gene. In this study, we characterize a new suppressor mutation that does not affect the production of AOX. It is a loss-of-function mutation in the gene encoding the MED13 subunit of the kinase module of the Mediator complex. Inactivation of the cdk8 gene encoding another subunit of the same module also results in partial suppression of a cytochrome-deficient mutant. Analysis of strains lacking the MED13 or CDK8 subunits points to the importance of these subunits as regulators involved in diverse physiological processes such as growth, longevity and sexual development. Interestingly, transcriptional analyses indicate that in P. anserina, loss of the respiratory cytochrome pathway results in the up-regulation of glycolysis-related genes revealing a new type of retrograde regulation. The loss of MED13 augments the up-regulation of some of these genes. PMID:26231682

  15. Identification of the het-r vegetative incompatibility gene of Podospora anserina as a member of the fast evolving HNWD gene family.

    Science.gov (United States)

    Chevanne, Damien; Bastiaans, Eric; Debets, Alfons; Saupe, Sven J; Clavé, Corinne; Paoletti, Mathieu

    2009-02-01

    In fungi, vegetative incompatibility is a conspecific non-self recognition mechanism that restricts formation of viable heterokaryons when incompatible alleles of specific het loci interact. In Podospora anserina, three non-allelic incompatibility systems have been genetically defined involving interactions between het-c and het-d, het-c and het-e, het-r and het-v. het-d and het-e are paralogues belonging to the HNWD gene family that encode proteins of the STAND class. HET-D and HET-E proteins comprise an N-terminal HET effector domain, a central GTP binding site and a C-terminal WD repeat domain constituted of tandem repeats of highly conserved WD40 repeat units that define the specificity of alleles during incompatibility. The WD40 repeat units of the members of this HNWD family are undergoing concerted evolution. By combining genetic analysis and gain of function experiments, we demonstrate that an additional member of this family, HNWD2, corresponds to the het-r non-allelic incompatibility gene. As for het-d and het-e, allele specificity at the het-r locus is determined by the WD repeat domain. Natural isolates show allelic variation for het-r. PMID:19137300

  16. Snow water equivalent modeling components in NewAge-JGrass

    Science.gov (United States)

    Formetta, G.; Kampf, S. K.; David, O.; Rigon, R.

    2014-05-01

    This paper presents a package of modified temperature-index-based snow water equivalent models as part of the hydrological modeling system NewAge-JGrass. Three temperature-based snow models are integrated into the NewAge-JGrass modeling system and use many of its components such as those for radiation balance (short wave radiation balance, SWRB), kriging (KRIGING), automatic calibration algorithms (particle swarm optimization) and tests of goodness of fit (NewAge-V), to build suitable modeling solutions (MS). Similarly to all the NewAge-JGrass components, the models can be executed both in raster and in vector mode. The simulation time step can be daily, hourly or sub-hourly, depending on user needs and availability of input data. The MS are applied on the Cache la Poudre River basin (CO, USA) using three test applications. First, daily snow water equivalent is simulated for three different measurement stations for two snow model formulations. Second, hourly snow water equivalent is simulated using all the three different snow model formulae. Finally, a raster mode application is performed to compute snow water equivalent maps for the whole Cache la Poudre Basin.

  17. Optimization of arterial age prediction models based in pulse wave

    International Nuclear Information System (INIS)

    We propose the detection of early arterial ageing through a prediction model of arterial age based in the coherence assumption between the pulse wave morphology and the patient's chronological age. Whereas we evaluate several methods, a Sugeno fuzzy inference system is selected. Models optimization is approached using hybrid methods: parameter adaptation with Artificial Neural Networks and Genetic Algorithms. Features selection was performed according with their projection on main factors of the Principal Components Analysis. The model performance was tested using the bootstrap error type .632E. The model presented an error smaller than 8.5%. This result encourages including this process as a diagnosis module into the device for pulse analysis that has been developed by the Bioengineering Laboratory staff

  18. Global Protein Oxidation Profiling Suggests Efficient Mitochondrial Proteome Homeostasis During Aging.

    Science.gov (United States)

    Ramallo Guevara, Carina; Philipp, Oliver; Hamann, Andrea; Werner, Alexandra; Osiewacz, Heinz D; Rexroth, Sascha; Rögner, Matthias; Poetsch, Ansgar

    2016-05-01

    The free radical theory of aging is based on the idea that reactive oxygen species (ROS) may lead to the accumulation of age-related protein oxidation. Because themajority of cellular ROS is generated at the respiratory electron transport chain, this study focuses on the mitochondrial proteome of the aging model Podospora anserina as target for ROS-induced damage. To ensure the detection of even low abundant modified peptides, separation by long gradient nLC-ESI-MS/MS and an appropriate statistical workflow for iTRAQ quantification was developed. Artificial protein oxidation was minimized by establishing gel-free sample preparation in the presence of reducing and iron-chelating agents. This first large scale, oxidative modification-centric study for P. anserina allowed the comprehensive quantification of 22 different oxidative amino acid modifications, and notably the quantitative comparison of oxidized and nonoxidized protein species. In total 2341 proteins were quantified. For 746 both protein species (unmodified and oxidatively modified) were detected and the modification sites determined. The data revealed that methionine residues are preferably oxidized. Further prominent identified modifications in decreasing order of occurrence were carbonylation as well as formation of N-formylkynurenine and pyrrolidinone. Interestingly, for the majority of proteins a positive correlation of changes in protein amount and oxidative damage were noticed, and a general decrease in protein amounts at late age. However, it was discovered that few proteins changed in oxidative damage in accordance with former reports. Our data suggest that P. anserina is efficiently capable to counteract ROS-induced protein damage during aging as long as protein de novo synthesis is functioning, ultimately leading to an overall constant relationship between damaged and undamaged protein species. These findings contradict a massive increase in protein oxidation during aging and rather suggest a

  19. Fragile DNA Repair Mechanism Reduces Ageing in Multicellular Model

    DEFF Research Database (Denmark)

    Bendtsen, Kristian Moss; Juul, Jeppe Søgaard; Trusina, Ala

    2012-01-01

    DNA damages, as well as mutations, increase with age. It is believed that these result from increased genotoxic stress and decreased capacity for DNA repair. The two causes are not independent, DNA damage can, for example, through mutations, compromise the capacity for DNA repair, which in turn...... increases the amount of unrepaired DNA damage. Despite this vicious circle, we ask, can cells maintain a high DNA repair capacity for some time or is repair capacity bound to continuously decline with age? We here present a simple mathematical model for ageing in multicellular systems where cells subjected...... to DNA damage can undergo full repair, go apoptotic, or accumulate mutations thus reducing DNA repair capacity. Our model predicts that at the tissue level repair rate does not continuously decline with age, but instead has a characteristic extended period of high and non-declining DNA repair...

  20. Ageing of palladium tritide: mechanical characterization, helium state and modelling

    International Nuclear Information System (INIS)

    Palladium is commonly used for the storage of tritium (the hydrogen radioactive isotope), since it forms a low-equilibrium-pressure and reversible tritide. Tritium decay into helium-3 is responsible for the ageing of the tritide, leading to the apparition of helium-3 bubbles for instance. Both experimental and theoretical aspects of this phenomenon are studied here.Previous works on ageing modelling led to two main models, dealing with:- Helium-3 bubbles nucleation (using a cellular automaton), - Bubbles growth (using continuum mechanics).These models were quite efficient, but their use was limited by the lack of input data and fitting experimental parameters.To get through these limitations, this work has consisted in studying the most relevant experimental data to improve the modelling of the palladium tritide ageing.The first part of this work was focused on the assessment of the mechanical properties of the palladium tritide (yield strength, ultimate strength, mechanical behaviour). They were deduced from the in situ tensile tests performed on palladium hydride and deuteride. In the second part, ageing characterization was undertaken, mainly focusing on: - Bubbles observations in palladium tritide using transmission electron microscopy, - Internal bubble pressure measurements using nuclear magnetic resonance, - Macroscopic swelling measurements using pycno-metry.The present work has led to significant progress in ageing understanding and has brought very valuable improvements to the modelling of such a phenomenon. (author)

  1. Age Dependencies in the Modelling of Radiation Carcinogenesis

    OpenAIRE

    Kellerer, Albrecht M.; Barclay, D

    1992-01-01

    Models for the dose and age dependence of radiation induced cancer have been based primarily on the follow-up of the atomic bomb survivors. Two different concepts have been deduced for leukaemias and for other cancers. The excess leukaemias appear in a distinct temporal wave with a maximum 5 to 10 years after radiation exposure; the distribution is more narrow for younger ages, but there is little dependence of the total attributable risk on age at exposure. For other cancers the latent perio...

  2. Age-dependent forest carbon sink: Estimation via inverse modeling

    Science.gov (United States)

    Zhou, Tao; Shi, Peijun; Jia, Gensuo; Dai, Yongjiu; Zhao, Xiang; Shangguan, Wei; Du, Ling; Wu, Hao; Luo, Yiqi

    2015-12-01

    Forests have been recognized to sequester a substantial amount of carbon (C) from the atmosphere. However, considerable uncertainty remains regarding the magnitude and time course of the C sink. Revealing the intrinsic relationship between forest age and C sink is crucial for reducing uncertainties in prediction of forest C sink potential. In this study, we developed a stepwise data assimilation approach to combine a process-based Terrestrial ECOsystem Regional model, observations from multiple sources, and stochastic sampling to inversely estimate carbon cycle parameters including carbon sink at different forest ages for evergreen needle-leaved forests in China. The new approach is effective to estimate age-dependent parameter of maximal light-use efficiency (R2 = 0.99) and, accordingly, can quantify a relationship between forest age and the vegetation and soil C sinks. The estimated ecosystem C sink increases rapidly with age, peaks at 0.451 kg C m-2 yr-1 at age 22 years (ranging from 0.421 to 0.465 kg C m-2 yr-1), and gradually decreases thereafter. The dynamic patterns of C sinks in vegetation and soil are significantly different. C sink in vegetation first increases rapidly with age and then decreases. C sink in soil, however, increases continuously with age; it acts as a C source when the age is less than 20 years, after which it acts as a sink. For the evergreen needle-leaved forest, the highest C sink efficiency (i.e., C sink per unit net primary productivity) is approximately 60%, with age between 11 and 43 years. Overall, the inverse estimation of carbon cycle parameters can make reasonable estimates of age-dependent C sequestration in forests.

  3. A SIRS epidemic model with infection-age dependence

    Science.gov (United States)

    Zhang, Zhonghua; Peng, Jigen

    2007-07-01

    Based on J. Mena-Lorca and H.W. Hethcote's epidemic model, a SIRS epidemic model with infection-age-dependent infectivity and general nonlinear contact rate is formulated. Under general conditions, the unique existence of its global positive solutions is obtained. Moreover, under more general assumptions than the existing, the existence and asymptotical stability of its equilibria are discussed. In the end, the condition on the stability of endemic equilibrium is verified by a special model.

  4. Fragile DNA repair mechanism reduces ageing in multicellular model.

    Directory of Open Access Journals (Sweden)

    Kristian Moss Bendtsen

    Full Text Available DNA damages, as well as mutations, increase with age. It is believed that these result from increased genotoxic stress and decreased capacity for DNA repair. The two causes are not independent, DNA damage can, for example, through mutations, compromise the capacity for DNA repair, which in turn increases the amount of unrepaired DNA damage. Despite this vicious circle, we ask, can cells maintain a high DNA repair capacity for some time or is repair capacity bound to continuously decline with age? We here present a simple mathematical model for ageing in multicellular systems where cells subjected to DNA damage can undergo full repair, go apoptotic, or accumulate mutations thus reducing DNA repair capacity. Our model predicts that at the tissue level repair rate does not continuously decline with age, but instead has a characteristic extended period of high and non-declining DNA repair capacity, followed by a rapid decline. Furthermore, the time of high functionality increases, and consequently slows down the ageing process, if the DNA repair mechanism itself is vulnerable to DNA damages. Although counterintuitive at first glance, a fragile repair mechanism allows for a faster removal of compromised cells, thus freeing the space for healthy peers. This finding might be a first step toward understanding why a mutation in single DNA repair protein (e.g. Wrn or Blm is not buffered by other repair proteins and therefore, leads to severe ageing disorders.

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

    Science.gov (United States)

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

    2009-01-01

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

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

    Science.gov (United States)

    Sauter, Sally T.

    2011-01-01

    Bioenergetics modeling can be used as a tool to investigate the impact of non-native age-0 American shad (Alosa sapidissima) on reservoir and estuary food webs. The model can increase our understanding of how these fish influence lower trophic levels as well as predatory fish populations that feed on juvenile salmonids. Bioenergetics modeling can be used to investigate ecological processes, evaluate alternative research hypotheses, provide decision support, and quantitative prediction. Bioenergetics modeling has proven to be extremely useful in fisheries research (Ney et al. 1993,Chips and Wahl 2008, Petersen et al. 2008). If growth and diet parameters are known, the bioenergetics model can be used to quantify the relative amount of zooplankton or insects consumed by age-0 American shad. When linked with spatial and temporal information on fish abundance, model output can guide inferential hypothesis development to demonstrate where the greatest impacts of age-0 American shad might occur. Bioenergetics modeling is particularly useful when research questions involve multiple species and trophic levels (e.g. plankton communities). Bioenergetics models are mass-balance equations where the energy acquired from food is partitioned between maintenance costs, waste products, and growth (Winberg 1956). Specifically, the Wisconsin bioenergetics model (Hanson et al. 1997) is widely used in fisheries science. Researchers have extensively tested, reviewed, and improved on this modeling approach for over 30 years (Petersen et al. 2008). Development of a bioenergetics model for any species requires three key components: 1) determine physiological parameters for the model through laboratory experiments or incorporate data from a closely related species, 2) corroboration of the model with growth and consumption estimates from independent research, and 3) error analysis of model parameters. Wisconsin bioenergetics models have been parameterized for many of the salmonids and

  7. An R package for fitting age, period and cohort models

    Directory of Open Access Journals (Sweden)

    Adriano Decarli

    2014-11-01

    Full Text Available In this paper we present the R implementation of a GLIM macro which fits age-period-cohort model following Osmond and Gardner. In addition to the estimates of the corresponding model, owing to the programming capability of R as an object oriented language, methods for printing, plotting and summarizing the results are provided. Furthermore, the researcher has fully access to the output of the main function (apc which returns all the models fitted within the function. It is so possible to critically evaluate the goodness of fit of the resulting model.

  8. Validating pathophysiological models of aging using clinical electronic medical records

    OpenAIRE

    CHEN, DAVID P.; Morgan, Alexander A; Atul J. Butte

    2009-01-01

    Bioinformatics methods that leverage the vast amounts of clinical data promises to provide insights into underlying molecular mechanisms that help explain human physiological processes. One of these processes is adolescent development. The utility of predictive aging models generated from cross-sectional cohorts and their applicability to separate populations, including the clinical population, has yet to be completely explored. In order to address this, we built regression models predictive ...

  9. Regulation of Aerobic Energy Metabolism in Podospora anserina by Two Paralogous Genes Encoding Structurally Different c-Subunits of ATP Synthase

    Science.gov (United States)

    Sellem, Carole H.; di Rago, Jean-Paul; Lasserre, Jean-Paul; Ackerman, Sharon H.; Sainsard-Chanet, Annie

    2016-01-01

    Most of the ATP in living cells is produced by an F-type ATP synthase. This enzyme uses the energy of a transmembrane electrochemical proton gradient to synthesize ATP from ADP and inorganic phosphate. Proton movements across the membrane domain (FO) of the ATP synthase drive the rotation of a ring of 8–15 c-subunits, which induces conformational changes in the catalytic part (F1) of the enzyme that ultimately promote ATP synthesis. Two paralogous nuclear genes, called Atp9-5 and Atp9-7, encode structurally different c-subunits in the filamentous fungus Podospora anserina. We have in this study identified differences in the expression pattern for the two genes that correlate with the mitotic activity of cells in vegetative mycelia: Atp9-7 is transcriptionally active in non-proliferating (stationary) cells while Atp9-5 is expressed in the cells at the extremity (apex) of filaments that divide and are responsible for mycelium growth. When active, the Atp9-5 gene sustains a much higher rate of c-subunit synthesis than Atp9-7. We further show that the ATP9-7 and ATP9-5 proteins have antagonist effects on the longevity of P. anserina. Finally, we provide evidence that the ATP9-5 protein sustains a higher rate of mitochondrial ATP synthesis and yield in ATP molecules per electron transferred to oxygen than the c-subunit encoded by Atp9-7. These findings reveal that the c-subunit genes play a key role in the modulation of ATP synthase production and activity along the life cycle of P. anserina. Such a degree of sophistication for regulating aerobic energy metabolism has not been described before. PMID:27442014

  10. Muscle wasting and aging: Experimental models, fatty infiltrations, and prevention.

    Science.gov (United States)

    Brioche, Thomas; Pagano, Allan F; Py, Guillaume; Chopard, Angèle

    2016-08-01

    Identification of cost-effective interventions to maintain muscle mass, muscle strength, and physical performance during muscle wasting and aging is an important public health challenge. It requires understanding of the cellular and molecular mechanisms involved. Muscle-deconditioning processes have been deciphered by means of several experimental models, bringing together the opportunities to devise comprehensive analysis of muscle wasting. Studies have increasingly recognized the importance of fatty infiltrations or intermuscular adipose tissue for the age-mediated loss of skeletal-muscle function and emphasized that this new important factor is closely linked to inactivity. The present review aims to address three main points. We first mainly focus on available experimental models involving cell, animal, or human experiments on muscle wasting. We next point out the role of intermuscular adipose tissue in muscle wasting and aging and try to highlight new findings concerning aging and muscle-resident mesenchymal stem cells called fibro/adipogenic progenitors by linking some cellular players implicated in both FAP fate modulation and advancing age. In the last part, we review the main data on the efficiency and molecular and cellular mechanisms by which exercise, replacement hormone therapies, and β-hydroxy-β-methylbutyrate prevent muscle wasting and sarcopenia. Finally, we will discuss a potential therapeutic target of sarcopenia: glucose 6-phosphate dehydrogenase. PMID:27106402

  11. Aging in a Model of Self-Organized Criticality

    International Nuclear Information System (INIS)

    Temporal autocorrelation functions for avalanches in the Bak-Sneppen model display aging behavior similar to glassy systems. Numerical simulations show that they decay as power laws with two distinct regimes separated by a time scale which is the waiting time, or age, of the avalanche. Thus, time-translational invariance is dynamically broken. The critical exponent of the initial decay is that of the familiar stationary dynamics while a new critical exponent for the late-time behavior appears. This new exponent characterizes a nonstationary regime that has not been previously considered in the context of self-organized criticality. copyright 1997 The American Physical Society

  12. Aging in a Model of Self-Organized Criticality

    Energy Technology Data Exchange (ETDEWEB)

    Boettcher, S. [Center for Theoretical Studies of Physical Systems, Clark Atlanta University, Atlanta, Georgia 30314 (United States); Boettcher, S. [Department of Physics and Astronomy, The University of Oklahoma, Norman, Oklahoma 73019-0225 (United States); Boettcher, S. [Center for Nonlinear Studies, MS-B258, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Paczuski, M. [Department of Physics, University of Houston, Houston, Texas 77204-5506 (United States)

    1997-08-01

    Temporal autocorrelation functions for avalanches in the Bak-Sneppen model display aging behavior similar to glassy systems. Numerical simulations show that they decay as power laws with two distinct regimes separated by a time scale which is the waiting time, or age, of the avalanche. Thus, time-translational invariance is dynamically broken. The critical exponent of the initial decay is that of the familiar stationary dynamics while a new critical exponent for the late-time behavior appears. This new exponent characterizes a nonstationary regime that has not been previously considered in the context of self-organized criticality. {copyright} {ital 1997} {ital The American Physical Society}

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

    Science.gov (United States)

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

    2015-02-01

    We introduce a one-parametric family of tree growth models, in which branching probabilities decrease with branch age τ as τ(-α). Depending on the exponent α, the scaling of tree depth with tree size n displays a transition between the logarithmic scaling of random trees and an algebraic growth. At the transition (α=1) tree depth grows as (logn)(2). This anomalous scaling is in good agreement with the trend observed in evolution of biological species, thus providing a theoretical support for age-dependent speciation and associating it to the occurrence of a critical point. PMID:25768548

  14. Modelling the genetic risk in age-related macular degeneration.

    Directory of Open Access Journals (Sweden)

    Felix Grassmann

    Full Text Available Late-stage age-related macular degeneration (AMD is a common sight-threatening disease of the central retina affecting approximately 1 in 30 Caucasians. Besides age and smoking, genetic variants from several gene loci have reproducibly been associated with this condition and likely explain a large proportion of disease. Here, we developed a genetic risk score (GRS for AMD based on 13 risk variants from eight gene loci. The model exhibited good discriminative accuracy, area-under-curve (AUC of the receiver-operating characteristic of 0.820, which was confirmed in a cross-validation approach. Noteworthy, younger AMD patients aged below 75 had a significantly higher mean GRS (1.87, 95% CI: 1.69-2.05 than patients aged 75 and above (1.45, 95% CI: 1.36-1.54. Based on five equally sized GRS intervals, we present a risk classification with a relative AMD risk of 64.0 (95% CI: 14.11-1131.96 for individuals in the highest category (GRS 3.44-5.18, 0.5% of the general population compared to subjects with the most common genetic background (GRS -0.05-1.70, 40.2% of general population. The highest GRS category identifies AMD patients with a sensitivity of 7.9% and a specificity of 99.9% when compared to the four lower categories. Modeling a general population around 85 years of age, 87.4% of individuals in the highest GRS category would be expected to develop AMD by that age. In contrast, only 2.2% of individuals in the two lowest GRS categories which represent almost 50% of the general population are expected to manifest AMD. Our findings underscore the large proportion of AMD cases explained by genetics particularly for younger AMD patients. The five-category risk classification could be useful for therapeutic stratification or for diagnostic testing purposes once preventive treatment is available.

  15. Carcinogen specific dosimetry model for passive smokers of various ages

    International Nuclear Information System (INIS)

    Studies indicate that being exposed to second hand smoke increases the chance of developing lung cancer. Understanding the deposition of carcinogenic particles present in second hand smoke is necessary to understand the development of specific histologic type cancers. In this study, a deposition model is presented for subjects of various ages exposed to sidestream smoke. The model included particle dynamics of coagulation, hygroscopic growth, charge and cloud behavior. Concentrations were varied from the maximum measured indoor concentrations (106 particles/cm3) to what would be expected from wisps of smoke (108 particles/cm3). Model results agreed well with experimental data taken from human subject deposition measurements (four studies). The model results were used to determine the dose intensity (dose per unit airway surface area) of Benzo[a]pyrene (BaP) in the respiratory tract for subjects of various ages. Model predictions for BaP surface concentration on the airway walls paralleled incident rates of tumors by location in the upper tracheobronchial region. Mass deposition efficiency was found to be larger for younger subjects, consistent with diffusion being the predominant mechanism for this particle size range. However, the actual dose intensity of BaP was found to be smaller for children than adults. This occurred due to the predominant effect of the smaller initial inhaled mass for children resulting from smaller tidal volumes. The resulting model is a useful tool to predict carcinogen specific particle deposition

  16. Anomalous scaling in an age-dependent branching model

    OpenAIRE

    Keller-Schmidt, Stephanie; Tugrul, Murat; Eguiluz, Victor M.; Hernandez-Garcia, Emilio; Klemm, Konstantin

    2010-01-01

    We introduce a one-parametric family of tree growth models, in which branching probabilities decrease with branch age $\\tau$ as $\\tau^{-\\alpha}$. Depending on the exponent $\\alpha$, the scaling of tree depth with tree size $n$ displays a transition between the logarithmic scaling of random trees and an algebraic growth. At the transition ($\\alpha=1$) tree depth grows as $(\\log n)^2$. This anomalous scaling is in good agreement with the trend observed in evolution of biological species, thus p...

  17. Anomalous scaling in an age-dependent branching model

    OpenAIRE

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

    2015-01-01

    We introduce a one-parametric family of tree growth models, in which branching probabilities decrease with branch age $\\tau$ as $\\tau^{-\\alpha}$. Depending on the exponent $\\alpha$, the scaling of tree depth with tree size $n$ displays a transition between the logarithmic scaling of random trees and an algebraic growth. At the transition ($\\alpha=1$) tree depth grows as $(\\log n)^2$. This anomalous scaling is in good agreement with the trend observed in evolution of biological species, thus p...

  18. SIVS EPIDEMIC MODELS WITH INFECTION AGE AND NONLINEAR VACCINATION RATE

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Vaccination is a very important strategy for the elimination of infectious diseaVaccination is a very important strategy for the elimination of infectious diseases. A SIVS epidemic model with infection age and nonlinear vaccination has been formulated in this paper. Using the theory of differential and integral equation, we show the local asymptotic stability of the infection-free equilibrium and the endemic equilibrium under some assumptions.

  19. Aging.

    Science.gov (United States)

    Park, Dong Choon; Yeo, Seung Geun

    2013-09-01

    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

  20. The Age-Competency Model to the Study of the Age-Wage Profiles for Workers

    CERN Document Server

    Maximov, S I

    2005-01-01

    In this article, I present a new approach and a novel model to the study of the life cycle of wages. The key idea is that wage can be thought as remuneration paid for the competency. It is assumed with the approach that there are three mechanisms acting at micro level and resulting in the change of workers' competencies during their lives. These are an endogenous growth of workers' initial competencies; a rate of investments in schooling in the life cycle of wages; and an effect of relative losses in workers' competencies. The developed model is to shed light on the processes resulting in the age-wage profiles seen in mass. The model obeys a nonlinear integro-differential equation. The found analytic solution of the equation has the form of Fisk PDF of a special type. The solution and its features are discussed. The regression technique is used to check the model upon reliability. The model provides better fitting to the data (Elo and Salonen, 2004) than minceraninan earnings function (Mincer, 1974) does.

  1. Mixing in age-structured population models of infectious diseases.

    Science.gov (United States)

    Glasser, John; Feng, Zhilan; Moylan, Andrew; Del Valle, Sara; Castillo-Chavez, Carlos

    2012-01-01

    Infectious diseases are controlled by reducing pathogen replication within or transmission between hosts. Models can reliably evaluate alternative strategies for curtailing transmission, but only if interpersonal mixing is represented realistically. Compartmental modelers commonly use convex combinations of contacts within and among groups of similarly aged individuals, respectively termed preferential and proportionate mixing. Recently published face-to-face conversation and time-use studies suggest that parents and children and co-workers also mix preferentially. As indirect effects arise from the off-diagonal elements of mixing matrices, these observations are exceedingly important. Accordingly, we refined the formula published by Jacquez et al. [19] to account for these newly-observed patterns and estimated age-specific fractions of contacts with each preferred group. As the ages of contemporaries need not be identical nor those of parents and children to differ by exactly the generation time, we also estimated the variances of the Gaussian distributions with which we replaced the Kronecker delta commonly used in theoretical studies. Our formulae reproduce observed patterns and can be used, given contacts, to estimate probabilities of infection on contact, infection rates, and reproduction numbers. As examples, we illustrate these calculations for influenza based on "attack rates" from a prospective household study during the 1957 pandemic and for varicella based on cumulative incidence estimated from a cross-sectional serological survey conducted from 1988-94, together with contact rates from the several face-to-face conversation and time-use studies. Susceptibility to infection on contact generally declines with age, but may be elevated among adolescents and adults with young children. PMID:22037144

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-05-31

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

  3. Test of magnetic susceptibility and grain-size age models of loess

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Ages of the stratigraphic boundary MIS1/2 and MIS3/4 of the Yuanbu loess section in Linxia are used as the basis of the nodal control age. The age of MIS1/2 and MIS3/4 are obtained from the latest international research result-the climatic events recorded in the stalagmite in the Hulu Cave in Nanjing, that MIS1/2 is 11.5 kaB. P. and MIS3/4 is 59.8 kaB.P.. The ages of the two climatic events contain three nodal age control models (Model 1: 0 kaB. P. -59.8 kaB. P.; Model 2: 0 kaB. P. -11.5 kaB. P. and 11.5kaB. P. -59.8 kaB. P.; Model 3: 11.5 kaB. P. -59.8 kaB. P. ), which are used as the nodal control age separately. The deposition times of various stratigraphic horizons are calculated by using the magnetic susceptibility age model and grain-size age model, and then compared with each other. In addition, the AMS14C age, OSL age and the ages of YD and H events are compared with the ages of the corresponding horizons calculated by the three models of nodal control ages. From the analyses of lithologic characters and climatic stages it has been found that both the magnetic susceptibility age model and the grain-size age model have some defects. Because the accurate control ages are selected as the nodal points of the glacial period or interglacial period, the stratigraphic deposition times determined by the high resolution of magnetic susceptibility age model and grain-size age model approximate to the actual ages. As for the relative accuracy of the two age models, the magnetic susceptibility age model is more accurate than the grain-size age model.

  4. Spectral Aging Model Applied to Meteosat First Generation Visible Band

    Directory of Open Access Journals (Sweden)

    Ilse Decoster

    2014-03-01

    Full Text Available The Meteosat satellites have been operational since the early eighties, creating so far a continuous time period of observations of more than 30 years. In order to use this data for climate data records, a consistent calibration is necessary between the consecutive instruments. Studies have shown that the Meteosat First Generation (MFG satellites (1982–2006 suffer from in-flight degradation which is spectral of nature and is not corrected by the official calibration of EUMETSAT. Continuing on previous published work by the same authors, this paper applies the spectral aging model to a set of clear-sky and cloudy targets, and derives the model parameters for all six MFG satellites (Meteosat-2 to -7. Several problems have been encountered, both due to the instrument and due to geophysical occurrences, and these are discussed and illustrated here in detail. The paper shows how the spectral aging model is an improvement compared to the EUMETSAT calibration method with a stability of 1%–2% for Meteosat-4 to -7, which increases up to 6% for ocean sites using the full MFG time period.

  5. Anomalous scaling in an age-dependent branching model

    OpenAIRE

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

    2015-01-01

    © 2015 American Physical Society. We introduce a one-parametric family of tree growth models, in which branching probabilities decrease with branch age τ as τ-α. Depending on the exponent α, the scaling of tree depth with tree size n displays a transition between the logarithmic scaling of random trees and an algebraic growth. At the transition (α=1) tree depth grows as (logn)2. This anomalous scaling is in good agreement with the trend observed in evolution of biological species, thus provid...

  6. The OMS3 JGrass-NewAge Environmental Modelling System

    Science.gov (United States)

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

    2012-12-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-09-01

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

  8. The aging feline kidney: a model mortality antagonist?

    Science.gov (United States)

    Lawler, Dennis F; Evans, Richard H; Chase, Kevin; Ellersieck, Mark; Li, Qinghong; Larson, Brian T; Satyaraj, Ebenezer; Heininger, Kurt

    2006-12-01

    Traditional thinking views apparently non-programmed disruptions of aging, which medical science calls geriatric diseases, as separate from 'less harmful' morphological and physiological aging phenotypes that are more universally expected with passage of time (loss of skin elasticity, graying of hair coat, weight gain, increased sleep time, behavioral changes, etc). Late-life disease phenotypes, especially those involving chronic processes, frequently are complex and very energy-expensive. A non-programmed process of homeostatic disruption leading into a death trajectory seems inconsistent with energy intensive processes. That is, evolutionary mechanisms do not favor complex and prolonged energy investment in death. Taking a different view, the naturally occurring feline (Felis silvestris catus) renal model suggests that at least some diseases of late life represent only the point of failure in essentially survival-driven adaptive processes. In the feline renal model, individuals that succumbed to failure most frequently displayed progressive tubular deletion and peritubular interstitial fibrosis, but had longer mean life span than cats that died from other causes. Additionally, among cats that died from non-renal causes, those that had degrees of renal tubular deletion and peritubular interstitial fibrosis also had longer mean life span than those cats with no changes, even though causes of death differed minimally between these latter two groups. The data indicate that selective tubular deletion very frequently begins early in adult life, without a clear initiating phase or event. The observations support a hypothesis that this prolonged process may be intrinsic and protective prior to an ultimate point of failure. Moreover, given the genetic complexity and the interplay with associated risk factors, existing data also do not support the ideas that these changes are simple compensatory responses and that breed- or strain-based 'default' diseases are inevitable

  9. Modeling Diverse Pathways to Age Progressive Volcanism in Subduction Zones.

    Science.gov (United States)

    Kincaid, C. R.; Szwaja, S.; Sylvia, R. T.; Druken, K. A.

    2015-12-01

    One of the best, and most challenging clues to unraveling mantle circulation patterns in subduction zones comes in the form of age progressive volcanic and geochemical trends. Hard fought geological data from many subduction zones, like Tonga-Lau, the Cascades and Costa-Rica/Nicaragua, reveal striking temporal patterns used in defining mantle flow directions and rates. We summarize results from laboratory subduction models showing a range in circulation and thermal-chemical transport processes. These interaction styles are capable of producing such trends, often reflecting apparent instead of actual mantle velocities. Lab experiments use a glucose working fluid to represent Earth's upper mantle and kinematically driven plates to produce a range in slab sinking and related wedge transport patterns. Kinematic forcing assumes most of the super-adiabatic temperature gradient available to drive major downwellings is in the tabular slabs. Moreover, sinking styles for fully dynamic subduction depend on many complicating factors that are only poorly understood and which can vary widely even for repeated parameter combinations. Kinematic models have the benefit of precise, repeatable control of slab motions and wedge flow responses. Results generated with these techniques show the evolution of near-surface thermal-chemical-rheological heterogeneities leads to age progressive surface expressions in a variety of ways. One set of experiments shows that rollback and back-arc extension combine to produce distinct modes of linear, age progressive melt delivery to the surface through a) erosion of the rheological boundary layer beneath the overriding plate, and deformation and redistribution of both b) mantle residuum produced from decompression melting and c) formerly active, buoyant plumes. Additional experiments consider buoyant diapirs rising in a wedge under the influence of rollback, back-arc spreading and slab-gaps. Strongly deflected diapirs, experiencing variable rise

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

    CERN Document Server

    Stroe, Andra; Hardcastle, Martin J; Röttgering, Huub J A

    2014-01-01

    CIZA J2242.8+5301 is a post-core passage, binary merging cluster that hosts a large, thin, arc-like radio relic, nicknamed the `Sausage', tracing a relatively strong shock front. We perform spatially-resolved spectral fitting to the available radio data for this radio relic, using a variety of spectral ageing models, with the aim of finding a consistent set of parameters for the shock and radio plasma. We determine an injection index of $0.77^{+0.03}_{-0.02}$ for the relic plasma, significantly steeper than was found before. Standard particle acceleration at the shock front implies a Mach number $M=2.90^{+0.10}_{-0.13}$, which now matches X-ray measurements. The shock advance speed is $v_\\mathrm{shock}\\approx2500$ km s$^{-1}$, which places the core passage of the two subclusters $0.6-0.8$ Gyr ago. We find a systematic spectral age increase from $0$ at the northern side of the relic up to $\\sim60$ Myr at $\\sim145$ kpc into the downstream area, assuming a $0.6$ nT magnetic field. Under the assumption of freely-...

  11. Ploidy, sex and crossing over in an evolutionary aging model

    Science.gov (United States)

    Lobo, Matheus P.; Onody, Roberto N.

    2006-02-01

    Nowadays, many forms of reproduction coexist in nature: Asexual, sexual, apomictic and meiotic parthenogenesis, hermaphroditism and parasex. The mechanisms of their evolution and what made them successful reproductive alternatives are very challenging and debated questions. Here, using a simple evolutionary aging model, we give a possible scenario. By studying the performance of populations where individuals may have diverse characteristics-different ploidies, sex with or without crossing over, as well as the absence of sex-we find an evolution sequence that may explain why there are actually two major or leading groups: Sexual and asexual. We also investigate the dependence of these characteristics on different conditions of fertility and deleterious mutations. Finally, if the primeval organisms on Earth were, in fact, asexual individuals we conjecture that the sexual form of reproduction could have more easily been set and found its niche during a period of low-intensity mutations.

  12. A review of successful aging models: proposing proactive coping as an important additional strategy.

    OpenAIRE

    Ouwehand, C.; Ridder, D.T.D. de; BENSING, J

    2007-01-01

    Successful aging is an important concept, and one that has been the subject of much research. During the last 15 years, the emphasis of this research has shifted from formulating criteria for successful aging to describing the processes involved in successful aging. The main purpose of the present article is to review psychological models of successful aging. The model of Selective Optimization with Compensation (SOC-model) proves to be one of the leading models in this field. Although eviden...

  13. Cellular models and therapies for age-related macular degeneration

    Directory of Open Access Journals (Sweden)

    David L. Forest

    2015-05-01

    Full Text Available Age-related macular degeneration (AMD is a complex neurodegenerative visual disorder that causes profound physical and psychosocial effects. Visual impairment in AMD is caused by the loss of retinal pigmented epithelium (RPE cells and the light-sensitive photoreceptor cells that they support. There is currently no effective treatment for the most common form of this disease (dry AMD. A new approach to treating AMD involves the transplantation of RPE cells derived from either human embryonic or induced pluripotent stem cells. Multiple clinical trials are being initiated using a variety of cell therapies. Although many animal models are available for AMD research, most do not recapitulate all aspects of the disease, hampering progress. However, the use of cultured RPE cells in AMD research is well established and, indeed, some of the more recently described RPE-based models show promise for investigating the molecular mechanisms of AMD and for screening drug candidates. Here, we discuss innovative cell-culture models of AMD and emerging stem-cell-based therapies for the treatment of this vision-robbing disease.

  14. Antioxidants in the Canine Model of Human Aging

    OpenAIRE

    Dowling, Amy L. S.; Head, Elizabeth

    2011-01-01

    Oxidative damage can lead to neuronal dysfunction in the brain due to modifications to proteins, lipids and DNA/RNA. In both human and canine brain, oxidative damage progressively increases with age. In the Alzheimer’s disease (AD) brain, oxidative damage is further exacerbated, possibly due to increased deposition of beta-amyloid (Aβ) peptide in senile plaques. These observations have led to the hypothesis that antioxidants may be beneficial for brain aging and AD. Aged dogs naturally develo...

  15. Characterizing cognitive aging of associative memory in animal models

    OpenAIRE

    Engle, James R.; Barnes, Carol A.

    2012-01-01

    An overview is provided of the simple single-cue delay and trace eyeblink conditioning paradigms as techniques to assess associative learning and memory in the aged. We highlight and focus this review on the optimization of the parameter space of eyeblink conditioning designs in the aged to avoid and control for potential confounds that may arise when studying aged mammals. The need to examine the contribution of non-associative factors that can contribute to performance outcomes is emphasize...

  16. Characterizing Cognitive Aging in Humans with Links to Animal Models

    OpenAIRE

    Alexander, Gene E.; Dawn Bowers; Foster, Thomas C.; Geldmacher, David S.

    2012-01-01

    With the population of older adults expected to grow rapidly over the next two decades, it has become increasingly important to advance research efforts to elucidate the mechanisms associated with cognitive aging, with the ultimate goal of developing effective interventions and prevention therapies. Although there has been a vast research literature on the use of cognitive tests to evaluate the effects of aging and age-related neurodegenerative disease, the need for a set of standardized meas...

  17. Four-vessel occlusion model using aged male Wistar rats: a reliable model to resolve the discrepancy related to age in cerebral ischemia research.

    Science.gov (United States)

    Ancer-Rodríguez, Jesús; Villarreal-Silva, Eliud Enrique; Salazar-Ybarra, Rodolfo Amador; Quiroga-García, Oscar; Rodríguez-Rocha, Humberto; García-García, Aracely; Morales-Avalos, Rodolfo; Morales-Gómez, Jesús Alberto; Quiroga-Garza, Alejandro; Saucedo-Cárdenas, Odila; Xu, Zao Cheng; Elizondo-Omaña, Rodrigo Enrique; Martínez-Ponce-de-León, Angel Raymundo; Guzmán-López, Santos

    2016-06-01

    Animal models of cerebral ischemia have typically been established and performed using young animals, even though cerebral ischemia (CI) affects primarily elderly patients. This situation represents a discrepancy that complicates the translation of novel therapeutic strategies for CI. Models of transient global CI using aged animals have demonstrated an apparent neuroprotective effect on CA1 hippocampal neurons; however, this effect is not completely understood. Our study used a model in which young (3-6 months) and aged (18-21 months) male Wistar rats were subjected to 15 min of transient global CI using the four-vessel occlusion (4 VO) model. We determined that the 4 VO model can be performed on aged rats with a slight increase in mortality rate. In aged rats, the morphological damage was completely established by the 4th day after reperfusion, displaying no difference from their younger counterparts. These results demonstrated the lack of a neuroprotective effect of aging on CA1 hippocampal neurons in aged male Wistar rats. This study determined and characterized the morphological damage to the CA1 area after 15 min of 4 VO in aged male Wistar rats, validating the use of this model in CI and aging research. PMID:25966656

  18. Age related aspects of physiology in respiratory tract modelling

    International Nuclear Information System (INIS)

    Dosimetric assessments for inhaled radionuclides require the use of age-related physiological parameters. The dimensions and masses of respiratory organs in children, aged 3 months, 1,5,10 and 25 years, and standard values for respiratory volumes such as functional residual capacity (FRC) have been reviewed. Airway dimensions were scaled to body sizes and masses to body weights. Daily inspired air volumes were calculated for each age for different physical activities and breathing rates. The same retention functions for deposited material have to be applied to adults and children because the available data provide no firm support for age specific values. (author)

  19. Towards a unified and interdisciplinary model of ageing.

    Science.gov (United States)

    Jameson, C W

    2004-01-01

    Researchers currently disagree about the appropriate biomarkers to monitor when measuring the ageing process. The major problem is identifying symptoms that are an end in and of themselves, from symptoms that are tied directly to the root cause, or causes, of ageing. This is most likely the reason that numerous, diverse and plausible theories for ageing co-exist. When young and old nuclei are exchanged between cells, the age of the resulting cell correlated with the nucleus. This suggests a large role of the nucleus as the target of ageing, although the sources of ageing may originate externally. There are three processes that occur when eukaryotes age. They are: (1) a progressive and patterned alteration of the structure of chromosomes after young adulthood has been reached, (2) a progressive and patterned malfunction of the degradation systems, and (3) age-altered post-translational modifications of proteins. A change in any one of these processes often causes a ripple effect that affects the other two processes. This paper begins by stating that the above three processes are the appropriate biomarkers of ageing. These three processes are coordinated with one another under normal physiological conditions. For example, proteasomes and their subunits have been found to regulate excision repair, transcription, and the turnover of nuclear/cytoplasmic receptors. The degradation system is also responsible for the removal of oxidized histones and other factors, which influence chromosome structure. Regulatory post-translational modifications at the histone level include methylation, phosphorylation, and acetylation. In addition, the above three processes undergo age related changes. Some of these modifications represent valid responses by the cell, but many do not. The effect of these age-altered macromolecules is perverse and unpredictable. For example, the cell's age-compromised degradation allows the accumulation of signaling complexes, which no longer match the

  20. Stability analysis of nonlinear integro-differential equations arising in age-dependent epidemic models

    International Nuclear Information System (INIS)

    An age-structured epidemic model of an SI type that incorporate vertical transmission is investigated when the fertility and mortality rates depend on age. We determine the steady states and examine their stabilities. (author). 13 refs

  1. Characterizing cognitive aging of associative memory in animal models

    Directory of Open Access Journals (Sweden)

    James R Engle

    2012-09-01

    Full Text Available An overview is provided of the simple single-cue delay and trace eyeblink conditioning paradigms as techniques to assess associative learning and memory in the aged. We highlight and focus this review on the optimization of the parameter space of eyeblink conditioning designs in the aged to avoid and control for potential confounds that may arise when studying aged mammals. The need to examine the contribution of non-associative factors that can contribute to performance outcomes is emphasized, and how age-related changes in the central nervous system as well as peripheral sensory factors can potentially bias the interpretation of the data in the aged is discussed. The way in which slight alterations of the parameter space in the delay and trace eyeblink conditioning paradigms can lead to delayed but intact conditioning, rather than impaired performance in aged animals is also discussed. Overall, the eyeblink conditioning paradigm, when optimized for the age of the animal in the study, is an elegantly simple technique for assessment of associative learning and memory. When design caveats described above are taken into account, this important type of memory, with its well-defined neural substrates, should definitely be included in cognitive assessment batteries for the aged.

  2. An agent-based computational model for tuberculosis spreading on age-structured populations

    Science.gov (United States)

    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.

  3. Urban groundwater age modeling under unconfined condition - Impact of underground structures on groundwater age: Evidence of a piston effect

    Science.gov (United States)

    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.

  4. The Cache la Poudre river basin snow water equivalent modeling with NewAge-JGrass

    OpenAIRE

    G. Formetta; S. K. Kampf; David, O.; R. Rigon

    2013-01-01

    The paper presents a snow water equivalent model as part of the hydrological modeling system NewAge-JGrass. The model take in account of the main physical processes influencing the snow melting (precipitation form separation, melting and freezing modeling) coupled with the snowpack mass conservation equation. The snow melting depends not only on the air temperature but also on the radiation received by the pixel. The model is perfectly integrated in the NewAge-JGrass modeling system an...

  5. Forecasting Age-Specific Brain Cancer Mortality Rates Using Functional Data Analysis Models

    OpenAIRE

    Pokhrel, Keshav P.; Tsokos, Chris P.

    2015-01-01

    Incidence and mortality rates are considered as a guideline for planning public health strategies and allocating resources. We apply functional data analysis techniques to model age-specific brain cancer mortality trend and forecast entire age-specific functions using exponential smoothing state-space models. The age-specific mortality curves are decomposed using principal component analysis and fit functional time series model with basis functions. Nonparametric smoothing methods are used to...

  6. Aging and Neurodegeneration: A Tangle of Models and Mechanisms.

    Science.gov (United States)

    Chakrabarti, Sasanka; Mohanakumar, Kochupurackal P

    2016-03-01

    The research on aging and age-related diseases, especially the neurodegenerative diseases, is on the fast track. However, the results have so far not been translated to actual benefit for the patients in terms of treatment or diagnosis of age-related degenerative diseases including those of the CNS. As far as the prevention of the cognitive decline during non-pathological aging is concerned, there is nothing much to offer other than calorie restriction and physical exercise. Needless to say, the benefits are not up to our expectations. However, over the years at the experimental level it has been possible to identify several cellular and molecular mechanisms that are intricately associated with aging in general and neurodegenerative diseases in particular. These include oxidative stress and altered redox-signaling, mitochondrial dysfunction, inflammation, proteotoxicity and altered gene expressions. These inter-dependent pathways mediate cellular senescence and often culminate in programmed cell death like apoptosis and autophagy, and in the context of brain these changes are manifested clinically as cognitive decline and pathologically as neurodegeneration. This special issue provides the readers with glimpses of this complex scenario from different angles primarily in the context of brain and also attempts to identify the potential drug targets against neurodegenerative diseases. PMID:27114843

  7. How does age affect baseline screening mammography performance measures? A decision model

    Directory of Open Access Journals (Sweden)

    Keen James E

    2008-09-01

    Full Text Available Abstract Background In order to promote consumer-oriented informed medical decision-making regarding screening mammography, we created a decision model to predict the age dependence of the cancer detection rate, the recall rate and the secondary performance measures (positive predictive values, total intervention rate, and positive biopsy fraction for a baseline mammogram. Methods We constructed a decision tree to model the possible outcomes of a baseline screening mammogram in women ages 35 to 65. We compared the single baseline screening mammogram decision with the no screening alternative. We used the Surveillance Epidemiology and End Results national cancer database as the primary input to estimate cancer prevalence. For other probabilities, the model used population-based estimates for screening mammography accuracy and diagnostic mammography outcomes specific to baseline exams. We varied radiologist performance for screening accuracy. Results The cancer detection rate increases from 1.9/1000 at age 40 to 7.2/1000 at age 50 to 15.1/1000 at age 60. The recall rate remains relatively stable at 142–157/1000, which varies from 73–236/1000 at age 50 depending on radiologist performance. The positive predictive value of a screening mammogram increases from 1.3% at age 40 to 9.8% at age 60, while the positive predictive value of a diagnostic mammogram varies from 2.9% at age 40 to 19.2% at age 60. The model predicts the total intervention rate = 0.013*AGE2 - 0.67*AGE + 40, or 34/1000 at age 40 to 47/1000 at age 60. Therefore, the positive biopsy (intervention fraction varies from 6% at age 40 to 32% at age 60. Conclusion Breast cancer prevalence, the cancer detection rate, and all secondary screening mammography performance measures increase substantially with age.

  8. On a System Modelling a Population with Two Age Groups

    Directory of Open Access Journals (Sweden)

    Hongliang Gao

    2014-01-01

    Full Text Available A system of first order ordinary differential equations describing a population divided into juvenile and adult age groups is studied. The system is not cooperative but its linear part is, and this makes it possible to establish the existence and nonexistence results of positive solutions for the system in terms of the principal eigenvalue of the corresponding linearized system.

  9. Incorporation of aging model in probabilistics safety assessment

    International Nuclear Information System (INIS)

    Probabilistic safety assessment (PSA) is a means of evaluating the comprehensive safety of nuclear power reactor including reactor design and operation. In general safety is analyzed assuming that reactor equipment and system are in average operating condition. But As reactor becomes aged the equipment malfunction rate increases. Many effort has been in progress for the effect of reactor aging to be reflected on PSA. Up to present PSA method has been applied mainly to active components like pumps and valves. This is because passive components like pipings generally demonstrates higher confidence than active components during initial reactor operation period. However accidents occurs often not only by active components, but also by passive components like that happened in Japan. In order to find out that how much does the degraded passive components' confidence affect power reactor safety the efforts have been made for aging of passive components to be reflected on PSA. This paper intends to introduce such activities to reflect aging effect on PSA. (Hong, J. S.)

  10. Ovarian Aging-Like Phenotype in the Hyperandrogenism-Induced Murine Model of Polycystic Ovary

    OpenAIRE

    Mohammad Amin Rezvanfar; Shojaei Saadi, Habib A; Maziar Gooshe; Amir Hosein Abdolghaffari; Maryam Baeeri; Mohammad Abdollahi

    2014-01-01

    There are prominently similar symptoms, effectors, and commonalities in the majority of characteristics between ovarian aging and polycystic ovarian syndrome (PCOS). Despite the approved role of oxidative stress in the pathogenesis of PCOS and aging, to our knowledge, the link between the PCO(S) and aging has not been investigated yet. In this study we investigated the possible exhibition of ovarian aging phenotype in murine model of PCO induced by daily oral administration of letrozole (1 mg...

  11. Phospholipase A2 - nexus of aging, oxidative stress, neuronal excitability and functional decline of the aging nervous system? Insights from a snail model system of neuronal aging and age-associated memory impairment.

    Directory of Open Access Journals (Sweden)

    Petra Maria Hermann

    2014-12-01

    Full Text Available TThe aging brain can undergo a range of changes varying from subtle structural and physiological changes causing only minor functional decline under healthy normal aging conditions, to severe cognitive or neurological impairment associated with extensive loss of neurons and circuits due to age-associated neurodegenerative disease conditions. Understanding how biological aging processes affect the brain and how they contribute to the onset and progress of age-associated neurodegenerative diseases is a core research goal in contemporary neuroscience. This review focuses on the idea that changes in intrinsic neuronal electrical excitability associated with (peroxidation of membrane lipids and activation of phospholipase A2 (PLA2 enzymes are an important mechanism of learning and memory failure under normal aging conditions. Specifically, in the context of this special issue on the Biology of cognitive aging we (1 portray the opportunities offered by the identifiable neurons and behaviorally characterized neural circuits of the freshwater snail Lymnaea stagnalis in neuronal aging research and (2 recapitulate recent insights indicating a key role of lipid peroxidation-induced PLA2 as instruments of aging, oxidative stress and inflammation in age-associated neuronal and memory impairment in this model system. The findings are discussed in view of accumulating evidence suggesting involvement of analogous mechanisms in the etiology of age-associated dysfunction and disease of the human and mammalian brain.

  12. Age Estimates of Universe: from Globular Clusters to Cosmological Models and Probes

    CERN Document Server

    Fatima, Hira; Rahman, Syed Faisal Ur

    2016-01-01

    We performed the photometric analysis of M2 and M92 globular clusters in g and r bands of SLOAN photometric system. We transformed these g and r bands into BV bands of Johnson-Cousins photometric system and built the color magnitude diagram (CMD). We estimated the age, and metallicity of both the clusters, by fitting Padova isochrones of different age and metallicities onto the CMD. We studied Einstein and de Sitter model, bench mark model, the cosmological parameters by WMAP and Planck surveys. Finally, we compared estimated age of globular clusters to the ages from the cosmological models and cosmological parameters values of WMAP and Planck surveys.

  13. Modeling the Information Age Combat Model: An Agent-Based Simulation of Network Centric Operations

    Science.gov (United States)

    Deller, Sean; Rabadi, Ghaith A.; Bell, Michael I.; Bowling, Shannon R.; Tolk, Andreas

    2010-01-01

    The Information Age Combat Model (IACM) was introduced by Cares in 2005 to contribute to the development of an understanding of the influence of connectivity on force effectiveness that can eventually lead to quantitative prediction and guidelines for design and employment. The structure of the IACM makes it clear that the Perron-Frobenius Eigenvalue is a quantifiable metric with which to measure the organization of a networked force. The results of recent experiments presented in Deller, et aI., (2009) indicate that the value of the Perron-Frobenius Eigenvalue is a significant measurement of the performance of an Information Age combat force. This was accomplished through the innovative use of an agent-based simulation to model the IACM and represents an initial contribution towards a new generation of combat models that are net-centric instead of using the current platform-centric approach. This paper describes the intent, challenges, design, and initial results of this agent-based simulation model.

  14. The impact of bias in length frequency data on an age structured fisheries stock assessment model

    OpenAIRE

    Heery, Eliza Crenshaw

    2007-01-01

    Statistical age-structured models are widely used in fisheries stock assessment. These models have been become increasingly complex over recent decades, allowing them to incorporate a larger variety of fisheries data. These typically include information regarding annual fishery yields, indices of abundance and catch composition data, which reflect the distribution of ages in the harvested population each year. In some fisheries, age composition can be determined annually through the examin...

  15. Mathematical Modelling and Experimental Analysis of Early Age Concrete

    DEFF Research Database (Denmark)

    Hauggaard-Nielsen, Anders Boe

    1997-01-01

    lead to cracks in the later cooling phase. The matrial model has intrigate couplings between the involved mechanics, and in the thesis special emphasize is put on the creep behaviour. The mathematical models are based on experimental analysis and numerical implementation of the models in a finite...

  16. Effects of tetrahydroxystilbene - glucoside on Animal Models of Dementia or Brain Aging

    Institute of Scientific and Technical Information of China (English)

    LinLi; JinChu; LiLiu; LingZhao; LanZhang

    2004-01-01

    Aim: To investigate the effects of 2, 3, 5, 4'-tetrahydroxystilbene-2-O-β-D-glucoside(TSG) from a Chinese Medicinal Herb polygonum multiflorum on dementia or brain aging. Methods. The brain aging model of mice was developed by s. c. injection of D-galactose (50mg/kg/day) for 60 days. The Alzheimer disease (AD) model of mice

  17. Abnormal glutamate release in aged BTBR mouse model of autism

    OpenAIRE

    Wei, Hongen; Ding, Caiyun; Jin, Guorong; Yin, Haizhen; Liu, Jianrong; Hu, Fengyun

    2015-01-01

    Autism is a neurodevelopmental disorder characterized by abnormal reciprocal social interactions, communication deficits, and repetitive behaviors with restricted interests. Most of the available research on autism is focused on children and young adults and little is known about the pathological alternation of autism in older adults. In order to investigate the neurobiological alternation of autism in old age stage, we compared the morphology and synaptic function of excitatory synapses betw...

  18. Muscle wasting in myotonic dystrophies: a model of premature aging.

    Directory of Open Access Journals (Sweden)

    Alba Judith eMateos-Aierdi

    2015-07-01

    Full Text Available Myotonic dystrophy type I (DM1 or Steinert’s disease and type II (DM2 are multisystem disorders of genetic origin. Progressive muscular weakness, atrophy and myotonia are the most prominent neuromuscular features of these diseases, and other clinical manifestations such as cardiomyopathy, insulin-resistance and cataracts are also common. From a clinical perspective, most DM symptoms are interpreted as a result of an accelerated aging (cataracts, muscular weakness and atrophy, cognitive decline, metabolic dysfunction, etc., including an increased risk of developing tumors. From this point of view, DM1 could be described as a progeroid syndrome since a notable age-dependent dysfunction of all systems occurs. The underlying molecular disorder in DM1 consists of the existence of a pathological (CTGn triplet expansion in the 3’ untranslated region of the DMPK gene, whereas (CCTGn repeats in the first intron of the CNBP/ZNF9 gene cause DM2. The expansions are transcribed into (CUGn and (CCUGn-containing RNA, respectively, which form secondary structures and sequester RNA-binding proteins, such as the splicing factor muscleblind-like protein (MBNL, forming nuclear aggregates known as foci. Other splicing factors, such as CUGBP, are also disrupted, leading to a spliceopathy of a large number of downstream genes linked to the clinical features of these diseases. Skeletal muscle regeneration relies on muscle progenitor cells, known as satellite cells, which are activated after muscle damage, and which proliferate and differentiate to muscle cells, thus regenerating the damaged tissue. Satellite cell dysfunction seems to be a common feature of both age-dependent muscle degeneration (sarcopenia and muscle wasting in DM and other muscle degenerative diseases. This review aims to describe the cellular, molecular and macrostructural processes involved in the muscular degeneration seen in DM patients, highlighting the similarities found with muscle aging.

  19. Practical applications of age-dependent reliability models and analysis of operational data

    International Nuclear Information System (INIS)

    The purpose of the workshop was to present the experience of practical application of time-dependent reliability models. The program of the workshop comprises the following sessions: -) aging management and aging PSA (Probabilistic Safety Assessment), -) modeling, -) operation experience, and -) accelerating aging tests. In order to introduce time aging effect of particular component to the PSA model, it has been proposed to use the constant unavailability values on the short period of time (one year for example) calculated on the basis of age-dependent reliability models. As for modeling, it appears that the problem of too detailed statistical models for application is the lack of data for required parameters. As for operating experience, several methods of operating experience analysis have been presented (algorithms for reliability data elaboration and statistical identification of aging trend). As for accelerated aging tests, it is demonstrated that a combination of operating experience analysis with the results of accelerated aging tests of naturally aged equipment could provide a good basis for continuous operation of instrumentation and control systems

  20. Practical applications of age-dependent reliability models and analysis of operational data

    Energy Technology Data Exchange (ETDEWEB)

    Lannoy, A.; Nitoi, M.; Backstrom, O.; Burgazzi, L.; Couallier, V.; Nikulin, M.; Derode, A.; Rodionov, A.; Atwood, C.; Fradet, F.; Antonov, A.; Berezhnoy, A.; Choi, S.Y.; Starr, F.; Dawson, J.; Palmen, H.; Clerjaud, L

    2005-07-01

    The purpose of the workshop was to present the experience of practical application of time-dependent reliability models. The program of the workshop comprises the following sessions: -) aging management and aging PSA (Probabilistic Safety Assessment), -) modeling, -) operation experience, and -) accelerating aging tests. In order to introduce time aging effect of particular component to the PSA model, it has been proposed to use the constant unavailability values on the short period of time (one year for example) calculated on the basis of age-dependent reliability models. As for modeling, it appears that the problem of too detailed statistical models for application is the lack of data for required parameters. As for operating experience, several methods of operating experience analysis have been presented (algorithms for reliability data elaboration and statistical identification of aging trend). As for accelerated aging tests, it is demonstrated that a combination of operating experience analysis with the results of accelerated aging tests of naturally aged equipment could provide a good basis for continuous operation of instrumentation and control systems.

  1. A statistical model including age to predict passenger postures in the rear seats of automobiles.

    Science.gov (United States)

    Park, Jangwoon; Ebert, Sheila M; Reed, Matthew P; Hallman, Jason J

    2016-06-01

    Few statistical models of rear seat passenger posture have been published, and none has taken into account the effects of occupant age. This study developed new statistical models for predicting passenger postures in the rear seats of automobiles. Postures of 89 adults with a wide range of age and body size were measured in a laboratory mock-up in seven seat configurations. Posture-prediction models for female and male passengers were separately developed by stepwise regression using age, body dimensions, seat configurations and two-way interactions as potential predictors. Passenger posture was significantly associated with age and the effects of other two-way interaction variables depended on age. A set of posture-prediction models are presented for women and men, and the prediction results are compared with previously published models. This study is the first study of passenger posture to include a large cohort of older passengers and the first to report a significant effect of age for adults. The presented models can be used to position computational and physical human models for vehicle design and assessment. Practitioner Summary: The significant effects of age, body dimensions and seat configuration on rear seat passenger posture were identified. The models can be used to accurately position computational human models or crash test dummies for older passengers in known rear seat configurations. PMID:26328769

  2. The Age-Competency Model to the Study of the Age-Wage Profiles for Workers

    OpenAIRE

    Maximov, S. I.

    2005-01-01

    In this article, I present a new approach and a novel model to the study of the life cycle of wages. The key idea is that wage can be thought as remuneration paid for the competency. It is assumed with the approach that there are three mechanisms acting at micro level and resulting in the change of workers' competencies during their lives. These are an endogenous growth of workers' initial competencies; a rate of investments in schooling in the life cycle of wages; and an effect of relative l...

  3. Modeling The Effects of Mother’s Age at First Birth on Child Health at Birth

    OpenAIRE

    Mbu Daniel Tambi

    2014-01-01

    This study models the impact of mother’s age at first birth on child health at birth in Cameroon. The objectives are: (1) investigate the implication of mother’s age at first birth on child health at birth; (2) examine the impact of mother’s age groups on birth weight, and (3) suggest economic policies to ameliorate the mother’s age – child health relationship. We make used of the control function approach to determine the relationship between mother’s age at first birth and birth...

  4. Age-related changes in predictive capacity versus internal model adaptability: electrophysiological evidence that individual differences outweigh effects of age

    Directory of Open Access Journals (Sweden)

    Ina eBornkessel-Schlesewsky

    2015-11-01

    Full Text Available Hierarchical predictive coding has been identified as a possible unifying principle of brain function, and recent work in cognitive neuroscience has examined how it may be affected by age–related changes. Using language comprehension as a test case, the present study aimed to dissociate age-related changes in prediction generation versus internal model adaptation following a prediction error. Event-related brain potentials (ERPs were measured in a group of older adults (60–81 years; n=40 as they read sentences of the form The opposite of black is white/yellow/nice. Replicating previous work in young adults, results showed a target-related P300 for the expected antonym (white; an effect assumed to reflect a prediction match, and a graded N400 effect for the two incongruous conditions (i.e. a larger N400 amplitude for the incongruous continuation not related to the expected antonym, nice, versus the incongruous associated condition, yellow. These effects were followed by a late positivity, again with a larger amplitude in the incongruous non-associated versus incongruous associated condition. Analyses using linear mixed-effects models showed that the target-related P300 effect and the N400 effect for the incongruous non-associated condition were both modulated by age, thus suggesting that age-related changes affect both prediction generation and model adaptation. However, effects of age were outweighed by the interindividual variability of ERP responses, as reflected in the high proportion of variance captured by the inclusion of by-condition random slopes for participants and items. We thus argue that – at both a neurophysiological and a functional level – the notion of general differences between language processing in young and older adults may only be of limited use, and that future research should seek to better understand the causes of interindividual variability in the ERP responses of older adults and its relation to cognitive

  5. The mouse as a model for understanding chronic diseases of aging: the histopathologic basis of aging in inbred mice

    Directory of Open Access Journals (Sweden)

    David Harrison

    2011-06-01

    Full Text Available Inbred mice provide a unique tool to study aging populations because of the genetic homogeneity within an inbred strain, their short life span, and the tools for analysis which are available. A large-scale longitudinal and cross-sectional aging study was conducted on 30 inbred strains to determine, using histopathology, the type and diversity of diseases mice develop as they age. These data provide tools that when linked with modern in silico genetic mapping tools, can begin to unravel the complex genetics of many of the common chronic diseases associated with aging in humans and other mammals. In addition, novel disease models were discovered in some strains, such as rhabdomyosarcoma in old A/J mice, to diseases affecting many but not all strains including pseudoxanthoma elasticum, pulmonary adenoma, alopecia areata, and many others. This extensive data set is now available online and provides a useful tool to help better understand strain-specific background diseases that can complicate interpretation of genetically engineered mice and other manipulatable mouse studies that utilize these strains.

  6. Maturity Models in the Age of Digital Diversity

    DEFF Research Database (Denmark)

    Andersen, Kim Normann; Henriksen, Helle Zinner; Medaglia, Rony

    2012-01-01

    -government maturity model by Layne and Lee [1] included in the proposal of the Public Sector Process Rebuilding (PPR) model [2, 3]. The adoption and adaptation of Web 2.0 platforms and location-based services, and the parallel extension of conventional technologies as SMS and web-based self-services, challenge the...... view that e-government is focused in a formal organizational span of control. We propose a refined operationalization of the PPR maturity model, arguing that the activities and individual workers within the public sector and the citizens using and co-producing the public services will be the vehicle of...

  7. Investigating Immune System Aging: System Dynamics and Agent-Based Modeling

    OpenAIRE

    Figueredo, Grazziela; Aickelin, Uwe

    2013-01-01

    System dynamics and agent based simulation models can both be used to model and understand interactions of entities within a population. Our modeling work presented here is concerned with understanding the suitability of the different types of simulation for the immune system aging problems and comparing their results. We are trying to answer questions such as: How fit is the immune system given a certain age? Would an immune boost be of therapeutic value, e.g. to improve the effectiveness...

  8. Mathematical Model of Three Age-Structured Transmission Dynamics of Chikungunya Virus

    Science.gov (United States)

    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.

  9. A virtual age model based on a bathtub shaped initial intensity

    Energy Technology Data Exchange (ETDEWEB)

    Dijoux, Yann [Laboratoire Jean Kuntzmann, Institut National Polytechnique de Grenoble, BP 53, 38 041 Grenoble Cedex 9 (France)], E-mail: yann.dijoux@imag.fr

    2009-05-15

    This paper presents a new reliability model for complex repairable systems, which combines a bathtub shaped ageing and imperfect maintenance. A bathtub shaped initial intensity function allows to take into account the burn-in period, the useful life and wear out of the systems. Repair effect is expressed by a reduction of the system virtual age, which depends on the ageing of the system. The main characteristics of the model are derived. The most important one is that the maintenance efficiency allows an extension of the system useful life duration. A statistical analysis of the model and an application to real failure data are presented.

  10. A virtual age model based on a bathtub shaped initial intensity

    International Nuclear Information System (INIS)

    This paper presents a new reliability model for complex repairable systems, which combines a bathtub shaped ageing and imperfect maintenance. A bathtub shaped initial intensity function allows to take into account the burn-in period, the useful life and wear out of the systems. Repair effect is expressed by a reduction of the system virtual age, which depends on the ageing of the system. The main characteristics of the model are derived. The most important one is that the maintenance efficiency allows an extension of the system useful life duration. A statistical analysis of the model and an application to real failure data are presented

  11. Bayesian Analysis of Hazard Regression Models under Order Restrictions on Covariate Effects and Ageing

    OpenAIRE

    Bhattacharjee, Arnab; Bhattacharjee, Madhuchhanda

    2007-01-01

    We propose Bayesian inference in hazard regression models where the baseline hazard is unknown, covariate effects are possibly age-varying (non-proportional), and there is multiplicative frailty with arbitrary distribution. Our framework incorporates a wide variety of order restrictions on covariate dependence and duration dependence (ageing). We propose estimation and evaluation of age-varying covariate effects when covariate dependence is monotone rather than proportional. In particular, we...

  12. Influence of Age on Ocular Biomechanical Properties in a Canine Glaucoma Model with ADAMTS10 Mutation

    OpenAIRE

    Palko, Joel R.; Morris, Hugh J.; Pan, Xueliang; Harman, Christine D.; Koehl, Kristin L.; Gelatt, Kirk N.; Plummer, Caryn E.; Komáromy, András M.; Liu, Jun

    2016-01-01

    Soft tissue often displays marked age-associated stiffening. This study aims to investigate how age affects scleral biomechanical properties in a canine glaucoma model with ADAMTS10 mutation, whose extracellular matrix is concomitantly influenced by the mutation and an increased mechanical load from an early age. Biomechanical data was acquired from ADAMTS10-mutant dogs (n = 10, 21 to 131 months) and normal dogs (n = 5, 69 to 113 months). Infusion testing was first performed in the whole glob...

  13. The optimal legal retirement age in an OLG model with endogenous labour supply

    OpenAIRE

    Hansen, Casper Worm; Lønstrup, Lars

    2009-01-01

    The long run welfare implications of the legal retirement age are studied in a perfect foresight overlapping-generations model where agents live for two periods. Agents’ lifetime is divided between working life and retirement by a legal retirement age controlled by the government whereas agents, besides savings, control the intensive margin or "yearly" labour supply. The legal retirement age is utilized to dampen distortionary effects of payroll taxes and public pension annuities and promote ...

  14. Characterizing cognitive aging of spatial and contextual memory in animal models

    OpenAIRE

    Foster, Thomas C.; Defazio, R. A.; Bizon, Jennifer L.

    2012-01-01

    Episodic memory, especially memory for contextual or spatial information, is particularly vulnerable to age-related decline in humans and animal models of aging. The continuing improvement of virtual environment technology for testing humans signifies that widely used procedures employed in the animal literature for examining spatial memory could be developed for examining age-related cognitive decline in humans. The current review examines cross species considerations for implementing these ...

  15. GPU-Accelerated Molecular Modeling Coming Of Age

    OpenAIRE

    Stone, John E.; Hardy, David J.; Ivan S. Ufimtsev; Schulten, Klaus

    2010-01-01

    Graphics processing units (GPUs) have traditionally been used in molecular modeling solely for visualization of molecular structures and animation of trajectories resulting from molecular dynamics simulations. Modern GPUs have evolved into fully programmable, massively parallel co-processors that can now be exploited to accelerate many scientific computations, typically providing about one order of magnitude speedup over CPU code and in special cases providing speedups of two orders of magnit...

  16. Lyapunov functions and global stability for SIR and SEIR models with age-dependent susceptibility

    KAUST Repository

    Korobeinikov, Andrei

    2013-01-01

    We consider global asymptotic properties for the SIR and SEIR age structured models for infectious diseases where the susceptibility depends on the age. Using the direct Lyapunov method with Volterra type Lyapunov functions, we establish conditions for the global stability of a unique endemic steady state and the infection-free steady state.

  17. Existence and Uniqueness of Endemic States for the Age-structured MSEIR Epidemic Model

    Institute of Scientific and Technical Information of China (English)

    Xue-zhi Li; Geni Gupur; Guang-tian Zhu

    2002-01-01

    The existence and uniqueness of positive steady states for the age-structured MSEIR epidemic model with age-dependent transmission coefficient is considered. Threshold results for the existence of endemic states are established; under certain conditions, uniqueness is also shown.

  18. Stability analysis of a general age-dependent vaccination model of a vertically transmitted disease

    International Nuclear Information System (INIS)

    An SIR epidemic model of a general age-dependent vaccination of a vertically as well as horizontally transmitted disease is investigated when the population is in steady state and the fertility, mortality and removal rates depends on age. We determine the steady states and examine their stabilities. (author). 24 refs

  19. Aging Well and the Environment: Toward an Integrative Model and Research Agenda for the Future

    Science.gov (United States)

    Wahl, Hans-Werner; Iwarsson, Susanne; Oswald, Frank

    2012-01-01

    Purpose of the Study: The effects of the physical-spatial-technical environment on aging well have been overlooked both conceptually and empirically. In the spirit of M. Powell Lawton's seminal work on aging and environment, this article attempts to rectify this situation by suggesting a new model of how older people interact with their…

  20. Combined age and segregated kinetic model for industrial-scale penicillin fed-batch cultivation

    NARCIS (Netherlands)

    Wang, Z.F.; Lauwerijssen, M.J.C.; Yuan, J.Q.

    2005-01-01

    This paper proposes a cell age model forPenicillium chrysogenum fed-batch cultivation to supply a qualitative insight into morphology-associated dynamics. The average ages of the segregated cell populations, such as growing cells, non-growing cells and intact productive cells, were estimated by this

  1. Conscientiousness, health, and aging: the life course of personality model.

    Science.gov (United States)

    Shanahan, Michael J; Hill, Patrick L; Roberts, Brent W; Eccles, Jacquelynne; Friedman, Howard S

    2014-05-01

    The Conscientiousness (C) of the self and significant others influences health by way of mediational chains involving socioeconomic attainment, the avoidance and neutralization of stressors, the promotion of health behaviors and the minimization of risk behaviors, and the management of symptoms and diseases. Yet, meta-analyses reveal that these associations are moderated by factors that are not well understood. We propose the Life Course of Personality Model (LCP Model), which comprises a series of hypotheses that suggest how such mediational chains are subject to 2 sources of contingency. First, the mechanisms by which C translates into health and the avoidance of risk change from early childhood to late adulthood, involving processes that are specific to phases of the life course; also, however, C influences health by way of continuous processes extending over many decades of life. Second, C may be more consequential in some social contexts than in others, and when accompanied by some constellations of personality characteristics than by others. That is, the mediational processes by which C translates into health and the avoidance of disease are likely moderated by timing, social context (including the C of others), and other aspects of the individual's personality. We consider methodological implications of the LCP Model. PMID:23244406

  2. The Age and Age Spread of the Praesepe and Hyades Clusters: a Consistent, ~800 Myr Picture from Rotating Stellar Models

    CERN Document Server

    Brandt, Timothy D

    2015-01-01

    We fit the upper main sequence of the Praesepe and Hyades open clusters using stellar models with and without rotation. When neglecting rotation, we find that no single isochrone can fit the entire upper main sequence at the clusters' spectroscopic metallicity: more massive stars appear, at high significance, to be younger than less massive stars. This discrepancy is consistent with earlier studies, but vanishes when including stellar rotation. The entire upper main sequence of both clusters is very well-fit by a distribution of 800 Myr-old stars with the spectroscopically measured [Fe/H]=0.12. The increase over the consensus age of ~600-650 Myr is due both to the revised Solar metallicity (from $Z_\\odot \\approx 0.02$ to $Z_\\odot \\approx 0.014$) and to the lengthening of main sequence lifetimes and increase in luminosities with rapid rotation. Our results show that rotation can remove the need for large age spreads in intermediate age clusters, and that these clusters may be significantly older than is common...

  3. Material modelling for creep-age forming of aluminium alloy 7B04

    Directory of Open Access Journals (Sweden)

    Lam Aaron C.L.

    2015-01-01

    Full Text Available This paper presents a study on the creep-ageing behaviour of a peak-aged aluminium alloy 7B04 under different tensile loads at 115oC and subsequently modelling it for creep-age forming (CAF applications. Mechanical properties and microstructural evolutions of creep-aged specimens were investigated. The material was modelled using a set of unified constitutive equations, which not only captures the material's creep deformation but also takes into account yield strength contributions from solid solution hardening, age hardening and dislocation hardening during creep-ageing. A possible application of the present work is demonstrated by implementing the determined material model into a commercial finite element analysis solver via a user-defined subroutine for springback prediction of creep-age formed plates. A good agreement is observed between the simulated springback values and experimental results. This material model now enables further investigations of 7B04 under various CAF scenarios to be conducted inexpensively via computational modelling.

  4. Mathematical modeling of left ventricular dimensional changes in mice during aging

    Directory of Open Access Journals (Sweden)

    Yang Tianyi

    2012-12-01

    Full Text Available Abstract Cardiac aging is characterized by diastolic dysfunction of the left ventricle (LV, which is due in part to increased LV wall stiffness. In the diastolic phase, myocytes are relaxed and extracellular matrix (ECM is a critical determinant to the changes of LV wall stiffness. To evaluate the effects of ECM composition on cardiac aging, we developed a mathematical model to predict LV dimension and wall stiffness changes in aging mice by integrating mechanical laws and our experimental results. We measured LV dimension, wall thickness, LV mass, and collagen content for wild type (WT C57/BL6J mice of ages ranging from 7.3 months to those of 34.0 months. The model was established using the thick wall theory and stretch-induced tissue growth to an isotropic and homogeneous elastic composite with mixed constituents. The initial conditions of the simulation were set based on the data from the young mice. Matlab simulations of this mathematical model demonstrated that the model captured the major features of LV remodeling with age and closely approximated experimental results. Specifically, the temporal progression of the LV interior and exterior dimensions demonstrated the same trend and order-of-magnitude change as our experimental results. In conclusion, we present here a validated mathematical model of cardiac aging that applies the thick-wall theory and stretch-induced tissue growth to LV remodeling with age.

  5. Modeling old-age wealth with endogenous early-life outcomes: The case of Mexico.

    Science.gov (United States)

    DeGraff, Deborah S; Wong, Rebeca

    2014-04-01

    This paper contributes to the literature on the life course and aging by examining the association between early-life outcomes and late-life well being, using data from the Mexican Health and Aging Study. Empirical research in this area has been challenged by the potential endogeneity of the early-life outcomes of interest, an issue which most studies ignore or downplay. Our contribution takes two forms: (1) we examine in detail the potential importance of two key life-cycle outcomes, age at marriage (a measure of family formation) and years of educational attainment (a measure of human capital investment) for old-age wealth, and (2) we illustrate the empirical value of past context variables that could help model the association between early-life outcomes and late-life well being. Our illustrative approach, matching macro-level historical policy and census variables to individual records to use as instruments in modeling the endogeneity of early-life behaviors, yields a statistically identified two-stage model of old-age wealth with minimum bias. We use simulations to show that the results for the model of wealth in old age are meaningfully different when comparing the approach that accounts for endogeneity with an approach that assumes exogeneity of early-life outcomes. Furthermore, our results suggest that in the Mexican case, models which ignore the potential endogeneity of early-life outcomes are likely to under-estimate the effects of such variables on old-age wealth. PMID:25170434

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

    Directory of Open Access Journals (Sweden)

    James R. Roede

    2013-01-01

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

  7. Degeneration of the Y chromosome in evolutionary aging models

    Science.gov (United States)

    Lobo, M. P.; Onody, R. N.

    2005-06-01

    The Y chromosomes are genetically degenerated and do not recombine with their matching partners X. Recombination of XX pairs is pointed out as the key factor for the Y chromosome degeneration. However, there is an additional evolutionary force driving sex-chromosomes evolution. Here we show this mechanism by means of two different evolutionary models, in which sex chromosomes with non-recombining XX and XY pairs of chromosomes is considered. Our results show three curious effects. First, we observed that even when both XX and XY pairs of chromosomes do not recombine, the Y chromosomes still degenerate. Second, the accumulation of mutations on Y chromosomes followed a completely different pattern then those accumulated on X chromosomes. And third, the models may differ with respect to sexual proportion. These findings suggest that a more primeval mechanism rules the evolution of Y chromosomes due exclusively to the sex-chromosomes asymmetry itself, i.e., the fact that Y chromosomes never experience female bodies. Over aeons, natural selection favored X chromosomes spontaneously, even if at the very beginning of evolution, both XX and XY pairs of chromosomes did not recombine.

  8. Increasing pulse wave velocity in a realistic cardiovascular model does not increase pulse pressure with age

    OpenAIRE

    Mohiuddin, Mohammad W.; Rihani, Ryan J.; Laine, Glen A.; Quick, Christopher M.

    2012-01-01

    The mechanism of the well-documented increase in aortic pulse pressure (PP) with age is disputed. Investigators assuming a classical windkessel model believe that increases in PP arise from decreases in total arterial compliance (Ctot) and increases in total peripheral resistance (Rtot) with age. Investigators assuming a more sophisticated pulse transmission model believe PP rises because increases in pulse wave velocity (cph) make the reflected pressure wave arrive earlier, augmenting systol...

  9. Disentangling the Age, Period, and Cohort Effects using a Modeling Approach

    OpenAIRE

    Portrait, France; Alessie, R.J.M.; Deeg, Dorly

    2002-01-01

    Disentangling age, period, and cohort effects in explaining health trends is crucial to assess future prevalences of health disorders. The identification problem -- age, period, and cohort effects are perfectly linearly related -- is tackled by modeling cohort and period effects using lifetime macro-indicators. This approach -- innovative in analyses on health trends -- handles theidentification problem and explains mechanisms underlying cohort and period effects. The modeling approach is com...

  10. Aging and Immortality in a Cell Proliferation Model

    CERN Document Server

    Antal, T; Trugman, S A; Redner, S

    2007-01-01

    We investigate a model of cell division in which the length of telomeres within the cell regulate their proliferative potential. At each cell division the ends of linear chromosomes change and a cell becomes senescent when one or more of its telomeres become shorter than a critical length. In addition to this systematic shortening, exchange of telomere DNA between the two daughter cells can occur at each cell division. We map this telomere dynamics onto a biased branching diffusion process with an absorbing boundary condition whenever any telomere reaches the critical length. As the relative effects of telomere shortening and cell division are varied, there is a phase transition between finite lifetime and infinite proliferation of the cell population. Using simple first-passage ideas, we quantify the nature of this transition.

  11. Modelling Anopheles gambiae s.s. Population Dynamics with Temperature- and Age-Dependent Survival.

    Science.gov (United States)

    Christiansen-Jucht, Céline; Erguler, Kamil; Shek, Chee Yan; Basáñez, María-Gloria; Parham, Paul E

    2015-06-01

    Climate change and global warming are emerging as important threats to human health, particularly through the potential increase in vector- and water-borne diseases. Environmental variables are known to affect substantially the population dynamics and abundance of the poikilothermic vectors of disease, but the exact extent of this sensitivity is not well established. Focusing on malaria and its main vector in Africa, Anopheles gambiae sensu stricto, we present a set of novel mathematical models of climate-driven mosquito population dynamics motivated by experimental data suggesting that in An. gambiae, mortality is temperature and age dependent. We compared the performance of these models to that of a "standard" model ignoring age dependence. We used a longitudinal dataset of vector abundance over 36 months in sub-Saharan Africa for comparison between models that incorporate age dependence and one that does not, and observe that age-dependent models consistently fitted the data better than the reference model. This highlights that including age dependence in the vector component of mosquito-borne disease models may be important to predict more reliably disease transmission dynamics. Further data and studies are needed to enable improved fitting, leading to more accurate and informative model predictions for the An. gambiae malaria vector as well as for other disease vectors. PMID:26030468

  12. Modelling Anopheles gambiae s.s. Population Dynamics with Temperature- and Age-Dependent Survival

    Science.gov (United States)

    Christiansen-Jucht, Céline; Erguler, Kamil; Shek, Chee Yan; Basáñez, María-Gloria; Parham, Paul E.

    2015-01-01

    Climate change and global warming are emerging as important threats to human health, particularly through the potential increase in vector- and water-borne diseases. Environmental variables are known to affect substantially the population dynamics and abundance of the poikilothermic vectors of disease, but the exact extent of this sensitivity is not well established. Focusing on malaria and its main vector in Africa, Anopheles gambiae sensu stricto, we present a set of novel mathematical models of climate-driven mosquito population dynamics motivated by experimental data suggesting that in An. gambiae, mortality is temperature and age dependent. We compared the performance of these models to that of a “standard” model ignoring age dependence. We used a longitudinal dataset of vector abundance over 36 months in sub-Saharan Africa for comparison between models that incorporate age dependence and one that does not, and observe that age-dependent models consistently fitted the data better than the reference model. This highlights that including age dependence in the vector component of mosquito-borne disease models may be important to predict more reliably disease transmission dynamics. Further data and studies are needed to enable improved fitting, leading to more accurate and informative model predictions for the An. gambiae malaria vector as well as for other disease vectors. PMID:26030468

  13. Atomistic Model of Physical Ageing in Se-rich As-Se Glasses

    Energy Technology Data Exchange (ETDEWEB)

    Golovchak,R.; Shpotyuk, O.; Kozdras, A.; Bureau, B.; Vlcek, M.; Ganjoo, A.; Jain, H.

    2007-01-01

    Thermal, optical, X-ray excited and magnetic methods were used to develop a microstructural model of physical ageing in Se-rich glasses. The glass composition As10Se90, possessing a typical cross-linked chain structure, was chosen as a model object for the investigations. The effect of physical ageing in this glass was revealed by differential scanning calorimetry, whereas the corresponding changes in its atomic arrangement were studied by extended X-ray absorption fine structure, Raman and solid-state 77Se nuclear magnetic resonance spectroscopy. Straightening-shrinkage processes are shown to be responsible for the physical ageing in this Se-rich As-Se glass.

  14. Rheological model for sol-gel phase transition of thermo-aged heavy oil fractions

    Directory of Open Access Journals (Sweden)

    Xiomara Andrea Vargas Arenas

    2010-05-01

    Full Text Available A power-law rheological model is proposed in this paper: G’’ (ω ∼ ωn and G’ (ω ~ ωn. It represents the increased connectivity between thermo-aged asphalt molecules in a rheo-reactor as one of the applications of systematic rheology. The results confirmed a sol-gel phase transition tendency for aged asphalt in the experimental frequency window at temperatures below 40°C. Such pattern could have been related to the structuring effect arising from the thermo-oxidative asphalt aging process during continuous agitation which has been suitably described by the micellar model of asphalt.

  15. Macroeconomic Impact of Population Aging in Japan: A Perspective from an Overlapping Generations Model

    OpenAIRE

    Muto, Ichiro; Oda, Takemasa; Sudo, Nao

    2012-01-01

    Due to a sharp decline in the fertility rate and a rapid increase in longevity, Japan's population aging is the furthest advanced in the world. In this study we explore the macroeconomic impact of population aging using a full-fledged overlapping generations model. Our model replicates well the time paths of Japan’s macroeconomic variables from the 1980s to the 2000s and yields future paths for these variables over a long horizon. We find that Japan’s population aging as a whole adversely aff...

  16. An evolutionary model of stature, age at first birth and reproductive success in Gambian women.

    OpenAIRE

    Allal, N.; Sear, R.; Prentice, A. M.; Mace, R.

    2004-01-01

    We have built a model to predict optimal age at first birth for women in a natural fertility population. The only existing fully evolutionary model, based on Ache hunter-gatherers, argues that as women gain weight, their fertility (rate of giving birth) increases-thus age at first birth represents a trade-off between time allocated to weight gain and greater fertility when mature. We identify the life-history implications of female age at first birth in a Gambian population, using uniquely de...

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

    CERN Document Server

    Rizzuto, Aaron C; Dupuy, Trent J; Kraus, Adam L

    2015-01-01

    We present the results of a long term orbit monitoring program, using sparse aperture masking observations taken with NIRC2 on the Keck-II telescope, of seven G to M-type members of the Upper Scorpius subgroup of the Sco-Cen OB association. We present astrometry and derived orbital elements of the binary systems we have monitored, and also determine the age, component masses, distance and reddening for each system using the orbital solutions and multi-band photometry, including Hubble Space Telescope photometry, and a Bayesian fitting procedure. We find that the models can be forced into agreement with any individual system by assuming an age, but that age is not consistent across the mass range of our sample. The G-type binary systems in our sample have model ages of ~11.5 Myr, which is consistent with the latest age estimates for Upper Scorpius, while the M-type binary systems have significantly younger model ages of ~7 Myr. Based on our fits, this age discrepancy in the models corresponds to a luminosity u...

  18. Compensatory renal hypertrophy and the handling of an acute nephrotoxicant in a model of aging.

    Science.gov (United States)

    Oliveira, Cláudia S; Joshee, Lucy; Zalups, Rudolfs K; Bridges, Christy C

    2016-03-01

    Aging often results in progressive losses of functioning nephrons, which can lead to a significant reduction in overall renal function. Because of age-related pathological changes, the remaining functional nephrons within aged kidneys may be unable to fully counteract physiological and/or toxicological challenges. We hypothesized that when the total functional renal mass of aged rats is reduced by 50%, the nephrons within the remnant kidney do not fully undergo the functional and physiological changes that are necessary to maintain normal fluid and solute homeostasis. We also tested the hypothesis that the disposition and handling of a nephrotoxicant are altered significantly in aged kidneys following an acute, 50% reduction in functional renal mass. To test these hypotheses, we examined molecular indices of renal cellular hypertrophy and the disposition of inorganic mercury (Hg(2+)), a model nephrotoxicant, in young control, young uninephrectomized (NPX), aged control and aged NPX Wistar rats. We found that the process of aging reduces the ability of the remnant kidney to undergo compensatory renal growth. In addition, we found that an additional reduction in renal mass in aged animals alters the disposition of Hg(2+) and potentially alters the risk of renal intoxication by this nephrotoxicant. To our knowledge, this study represents the first report of the handling of a nephrotoxicant in an aged animal following a 50% reduction in functional renal mass. PMID:26768998

  19. A Drosophila model for age-associated changes in sleep:wake cycles.

    Science.gov (United States)

    Koh, Kyunghee; Evans, Joshua M; Hendricks, Joan C; Sehgal, Amita

    2006-09-12

    One of the most consistent behavioral changes that occurs with age in humans is the loss of sleep consolidation. This can be quite disruptive and yet little is known about its underlying basis. To better understand the effects of aging on sleep:wake cycles, we sought to study this problem in Drosophila melanogaster, a powerful system for research on aging and behavior. By assaying flies of different ages as well as monitoring individual flies constantly over the course of their lifetime, we found that the strength of sleep:wake cycles decreased and that sleep became more fragmented with age in Drosophila. These changes in sleep:wake cycles became faster or slower with manipulations of ambient temperature that decreased or increased lifespan, respectively, demonstrating that they are a function of physiological rather than chronological age. The effect of temperature on lifespan was not mediated by changes in overall activity level or sleep amount. Flies treated with the oxidative stress-producing reagent paraquat showed a breakdown of sleep:wake cycles similar to that seen with aging, leading us to propose that the accumulation of oxidative damage with age contributes to the changes in rhythm and sleep. Together, these findings establish Drosophila as a valuable model for studying age-associated sleep fragmentation and breakdown of rhythm strength, and indicate that these changes in sleep:wake cycles are an integral part of the physiological aging process. PMID:16938867

  20. Fragility Modeling of Aging Containment Metallic Pressure Boundaries

    International Nuclear Information System (INIS)

    The containment in a nuclear power plant (NPP) provides a barrier against the release of radioactivity in the event of an accident. Corrosion that has been observed in some steel containments and liners of reinforced concrete containments has raised questions about their ability to perform this function. The performance of corroded containments during events at or beyond the design basis is impacted by numerous sources of uncertainty. A fragility model of the containment provides a relatively simple depiction of the impact of uncertainties on structural performance and a basis for decision-making in the presence of uncertainty. Moreover, it is a necessary ingredient of any time-dependent structural reliability analysis. A nonlinear finite element analysis of containment response furnishes the necessary platform to perform numerical experiments to determine containment fragility. A statistically-based sampling plan minimizes the finite element computations required to develop the fragility curve. The -percentile (or other fractile) then gives a statistically based indication of the lower bound on containment capacity, and can be used as a screening tool to determine whether more refined further analysis or tests to support service life evaluations are warranted

  1. Multi-physics Model for the Aging Prediction of a Vanadium Redox Flow Battery System

    International Nuclear Information System (INIS)

    Highlights: • Present a multi-physics model of vanadium redox-flow battery. • This model is essential for aging prediction. • It is applicable for VRB system of different power and capacity ratings. • Good results comparing with current research in this field. - Abstract: The all-vanadium redox-flow battery is an attractive candidate to compensate the fluctuations of non-dispatchable renewable energy generation. While several models for vanadium redox batteries have been described yet, no model has been published, which is adequate for the aging prediction. Therefore, the present paper presents a multi-physics model which determines all parameters that are essential for an aging prediction. In a following paper, the corresponding aging model of vanadium redox flow battery (VRB) is described. The model combines existing models for the mechanical losses and temperature development with new approaches for the batteries side reactions. The model was implemented in Matlab/Simulink. The modeling results presented in the paper prove to be consistent with the experimental results of other research groups

  2. Decision support for life extension of technical systems through virtual age modelling

    International Nuclear Information System (INIS)

    This article presents a virtual age model for decision support regarding life extension of ageing repairable systems. The aim of the model is to evaluate different life extension decision alternatives and their impact on the future performance of the system. The model can be applied to systems operated continuously (e.g., process systems) and systems operated on demand (e.g., safety systems). Deterioration and efficiency of imperfect maintenance is assessed when there is limited or no degradation data, and only failure and maintenance data is available. Systems that are in operation can be studied, meaning that the systems may be degraded. The current degradation is represented by a “current virtual age”, which is calculated from recorded maintenance data. The model parameters are estimated with the maximum likelihood method. A case study illustrates the application of the model for life extension of two fire water pumps in an oil and gas facility. The performance of the pump system is assessed with respect to number of failures, safety unavailability and costs during the life extension period. -- Highlights: ► Life extension assessment of technical systems using virtual age model is proposed. ► A virtual age model is generalised for systems in stand-by and continuous operation. ► The concept of current virtual age describes technical condition of the system. ► Different decision alternatives for life extension can be easily analysed. ► The decision process is improved even when only scarce failure data is available

  3. Markov Chain-Like Quantum Biological Modeling of Mutations, Aging, and Evolution

    Directory of Open Access Journals (Sweden)

    Ivan B. Djordjevic

    2015-08-01

    Full Text Available Recent evidence suggests that quantum mechanics is relevant in photosynthesis, magnetoreception, enzymatic catalytic reactions, olfactory reception, photoreception, genetics, electron-transfer in proteins, and evolution; to mention few. In our recent paper published in Life, we have derived the operator-sum representation of a biological channel based on codon basekets, and determined the quantum channel model suitable for study of the quantum biological channel capacity. However, this model is essentially memoryless and it is not able to properly model the propagation of mutation errors in time, the process of aging, and evolution of genetic information through generations. To solve for these problems, we propose novel quantum mechanical models to accurately describe the process of creation spontaneous, induced, and adaptive mutations and their propagation in time. Different biological channel models with memory, proposed in this paper, include: (i Markovian classical model, (ii Markovian-like quantum model, and (iii hybrid quantum-classical model. We then apply these models in a study of aging and evolution of quantum biological channel capacity through generations. We also discuss key differences of these models with respect to a multilevel symmetric channel-based Markovian model and a Kimura model-based Markovian process. These models are quite general and applicable to many open problems in biology, not only biological channel capacity, which is the main focus of the paper. We will show that the famous quantum Master equation approach, commonly used to describe different biological processes, is just the first-order approximation of the proposed quantum Markov chain-like model, when the observation interval tends to zero. One of the important implications of this model is that the aging phenotype becomes determined by different underlying transition probabilities in both programmed and random (damage Markov chain-like models of aging, which

  4. Modeling the effect of age in T1-2 breast cancer using the SEER database

    Directory of Open Access Journals (Sweden)

    Lee Sang-Joon

    2005-10-01

    Full Text Available Abstract Background Modeling the relationship between age and mortality for breast cancer patients may have important prognostic and therapeutic implications. Methods Data from 9 registries of the Surveillance, Epidemiology, and End Results Program (SEER of the United States were used. This study employed proportional hazards to model mortality in women with T1-2 breast cancers. The residuals of the model were used to examine the effect of age on mortality. This procedure was applied to node-negative (N0 and node-positive (N+ patients. All causes mortality and breast cancer specific mortality were evaluated. Results The relationship between age and mortality is biphasic. For both N0 and N+ patients among the T1-2 group, the analysis suggested two age components. One component is linear and corresponds to a natural increase of mortality with each year of age. The other component is quasi-quadratic and is centered around age 50. This component contributes to an increased risk of mortality as age increases beyond 50. It suggests a hormonally related process: the farther from menopause in either direction, the more prognosis is adversely influenced by the quasi-quadratic component. There is a complex relationship between hormone receptor status and other prognostic factors, like age. Conclusion The present analysis confirms the findings of many epidemiological and clinical trials that the relationship between age and mortality is biphasic. Compared with older patients, young women experience an abnormally high risk of death. Among elderly patients, the risk of death from breast cancer does not decrease with increasing age. These facts are important in the discussion of options for adjuvant treatment with breast cancer patients.

  5. Growth and Microhardness of the Rat’s Tibia in Different Ages after Fracture Modeling

    Directory of Open Access Journals (Sweden)

    Andrii N. Bushtruk

    2014-06-01

    Full Text Available Bone injury is a powerful factor that leads to remodeling of the entire organ. When this change rate adjustment processes dependent on many factors including the age. There is strong evidence of changes in the skeleton of a young, mature and old age in terms of long bone injuries. But it is poorly understood changes in other age periods. The aim of our work was to study bone growth and bone microhardness after defect modeling of the tibia in animals of different age periods. Under sterile operating was applied defect of medial surface of the body with the middle third of the tibia. After 10, 15 and 24 days after defect application were study osteometric parameters and bone microhardness. Tibia injury leads to disruption of the longitudinal growth processes in animals of young and adult ages, which is probably due to dysfunction of the epiphyseal growth plate. Also seen the development of periosteal reaction, which is accompanied by changes in the transverse dimensions of the bone. In animals of presenile and senile ages were not observe changes of bone growth parameters. Microhardness bone tends to lower in animals of all ages. While in rats of young and adult ages observed normalization of this parameter to the 24 day, in animals of presenile and senile age there is a decrease of microhardness, which is a risk factor for recurrent fractures.

  6. Mathematical Modeling of Age and of Income Distribution Associated with Female Marriage Migration in Rajshahi, Bangladesh

    Directory of Open Access Journals (Sweden)

    Rafiqul Islam

    2012-08-01

    Full Text Available An effort has been made, in this study, to fit mathematical models to age and income distribution associated with female marriage migration in Rajshahi district, Bangladesh. For this, the data is taken under the project entitled “Strengthening the Department of Population Science and Human Resource Development” in collaboration with UNFPA, Bangladesh. It is found that marriage migration associated with age follows polynomial model and income distribution associated with female marriage migration follows two parameters positive exponential model. To verify the adequacy and steadiness situation of the model, Cross Validity Prediction Power (CVPP and F-test are employed to these models. The contribution of this paper to knowledge is the fitted cubic polynomial model and positive exponential model to the migration data aggregate.

  7. Realistic modeling of environmental tracer migration and composite age distributions in a pine beetle impacted watershed

    Science.gov (United States)

    Engdahl, N. B.; Maxwell, R. M.

    2013-12-01

    Descriptions of age in hydrologic systems are often limited to the residence time in the surface water system or the subsurface with little consideration of the interaction between the two, or the different ways geochemical tracers are altered in each domain. Understanding the way tracer concentrations change in each domain is essential to accurate estimation of age, but few models have explicitly modeled the fully coupled system or considered distributions of age. This work presents a numerical laboratory that is specifically designed to investigate composite age distributions (CADs) and their connections to tracer concentrations. The CAD is defined here as the combination of the residence time distributions for surface flows, vadose zone, and groundwater systems, providing an accounting for the total time a discrete fluid parcel has spent within the integrated hydrologic system. CADs are generated by particle tracking through a fully integrated flow model and it is straight forward to realistically simulate the transport of environmental tracers such as 85-Krypton and 39-Argon that can be used for estimating water ages. This framework allows explicit modeling of the different processes in each domain that affect tracer concentrations including the mixing of different source waters, partial equilibrium with the atmosphere through the vadose zone, evaporative enrichment in surface flows, and diffusive fractionation in the subsurface. Transient forcings, such as seasonal or daily variations in precipitation, can also be simulated and the effects of this transience on concentrations and age distributions can easily be investigated. The model domain used to demonstrate these tools is based on a well-defined watershed within Rocky Mountain National Park. The mountain pine beetle has devastated the park's forests and the massive tree-kill has begun to affect the quality and distribution of the water resources. Accurate modeling of the CADs in the park is a crucial step

  8. A preliminary approach to age-dependent deposition modeling for human respiratory tract

    International Nuclear Information System (INIS)

    Since the respiratory tract model, presented by the ICRP Task Group on Lung Dynamics, is limited to adult workers for determining internal radiation exposure from inhaled radionuclides, the development of the model for estimating radiation doses in the general public, including all age groups, from environmental radioactive materials is required. This paper provides background information in developing the age-dependent respiratory tract model. A way of obtaining deposition probability through major mechanisms, such as impaction, sedimentation, and diffusion, in the respiratory airways is given. A computer program for estimating the percent deposition of inhaled monodisperse particles is described. (Namekawa, K.)

  9. Age- and bite-structured models for vector-borne diseases

    OpenAIRE

    K.S. Rock; Wood, D A; Keeling, M J

    2015-01-01

    The biology and behaviour of biting insects is a vitally important aspect in the spread of vector-borne diseases. This paper aims to determine, through the use of mathematical models, what effect incorporating vector senescence and realistic feeding patterns has on disease. A novel model is developed to enable the effects of age- and bite-structure to be examined in detail. This original PDE framework extends previous age-structured models into a further dimension to give a new insight into t...

  10. Analytical model for unavailability due to aging failures in power systems

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Kaigui [State Key Laboratory of Power Transmission Equipment and System Security and New Technology at Chongqing University, College of Electrical Engineering, Chongqing 400044 (China); Li, Wenyuan [System Planning and Performance Assessment, BC Transmission Corporation, Vancouver (Canada)

    2009-09-15

    Power system component failures can generally be classified into two categories: repairable random failures and aging failures. An essential step in power system reliability evaluation is the calculation of component unavailability. The paper presents a new model for calculating the unavailability due to aging failures using the normal distribution. It is based on the strictly mathematical derivation and can be used more easily with high accuracy compared to the traditional model. An example of seven generating units and two test systems of the RBTS and the IEEE-RTS were used to demonstrate effectiveness of the proposed model and its applications in power system reliability evaluation. (author)

  11. Development of an Age- and Gender-specific Model for Strontium Metabolism in Humans

    Energy Technology Data Exchange (ETDEWEB)

    Shagina, N. B.; Degteva, M. O.; Tolstykh, E. I.

    2004-07-01

    This paper presents a development of a new biokinetic model for strontium, which accounts for age and gender differences of metabolism in humans. This model was developed based on the long-term follow-up of the residents living on the banks of the Techa River (Southern Urals, Russia) contaminated with 89,90Sr in 1950-1956. The new model uses the structure of ICRP model for strontium but model parameters have been estimated to account for age, gender and population differences in strontium retention and elimination. Estimates of age- and gender-specific model parameters were derived from (a) the results of long-term measurements of 90Sr-body burden for the Techa River population; (b) experimental studies of calcium and strontium metabolism in humans and (c) non-radiological data regarding bone metabolism (mineral content of the body, bone turnover, etc). As a result, the new model satisfactorily describes data on long-term retention of 90Sr in residents of the Techa River settlements of all ages and both genders and also data from studies during the period of global fallout in the UK and the USA and experimental data on strontium retention in humans. The new model can be used to calculate dose from 89,90Sr for the Techa River residents and also for other populations with similar parameters of skeletal maturation and also for other populations with similar parameters of skeletal maturation and involution. (Author) 27 refs.

  12. A Third Note on Ageing in a Library Circulation Model: Applications to Future Use and Relegation.

    Science.gov (United States)

    Burrell, Quentin L.

    1987-01-01

    Describes a circulation model for academic research libraries which uses the mixed Poisson model, incorporating ageing of library materials, to predict future use of monographs and to suggest weeding procedures based on frequency of circulation. Longitudinal studies are examined and statistical details are appended. (Author/LRW)

  13. The Cache la Poudre river basin snow water equivalent modeling with NewAge-JGrass

    Directory of Open Access Journals (Sweden)

    G. Formetta

    2013-08-01

    Full Text Available The paper presents a snow water equivalent model as part of the hydrological modeling system NewAge-JGrass. The model take in account of the main physical processes influencing the snow melting (precipitation form separation, melting and freezing modeling coupled with the snowpack mass conservation equation. The snow melting depends not only on the air temperature but also on the radiation received by the pixel. The model is perfectly integrated in the NewAge-JGrass modeling system and uses many of its components such as shortwave radiation balance, krigings and automatic calibration algorithms. As all the NewAge-JGrass components, the presented model can be executed both in raster and in vector mode and the simulation time step can be daily, hourly or sub-hourly as the user needs. The model is applied on the Cache la Poudre river basin (CO, USA. Three are the applications presented in the paper. Firstly, the simulation of snow water equivalent in three different measurement stations is performed. Model parameters are calibrated and model performances are quantitatively computed by comparing simulated and measured snow water equivalent time series. Indices of goodness of fit such as Kling–Gupta Efficiency, Index of Agreement and Percentage Bias are computed. Secondly, the representativeness of the model parameters in different locations is discussed. Finally a raster mode application is performed: snow water equilvalent maps on the whole Cache la Poudre river are computed. In all the applications the model performance are satisfactory in term of goodness of fitting measured snow water equivalent time series. The integration of the model in the NewAge-JGrass system allows the used to o enjoy all the component of the system: input data computation, output maps visualizetion in the GIS JGrass, model parameters automatic calibration.

  14. The Cache la Poudre river basin snow water equivalent modeling with NewAge-JGrass

    Science.gov (United States)

    Formetta, G.; Kampf, S. K.; David, O.; Rigon, R.

    2013-08-01

    The paper presents a snow water equivalent model as part of the hydrological modeling system NewAge-JGrass. The model take in account of the main physical processes influencing the snow melting (precipitation form separation, melting and freezing modeling) coupled with the snowpack mass conservation equation. The snow melting depends not only on the air temperature but also on the radiation received by the pixel. The model is perfectly integrated in the NewAge-JGrass modeling system and uses many of its components such as shortwave radiation balance, krigings and automatic calibration algorithms. As all the NewAge-JGrass components, the presented model can be executed both in raster and in vector mode and the simulation time step can be daily, hourly or sub-hourly as the user needs. The model is applied on the Cache la Poudre river basin (CO, USA). Three are the applications presented in the paper. Firstly, the simulation of snow water equivalent in three different measurement stations is performed. Model parameters are calibrated and model performances are quantitatively computed by comparing simulated and measured snow water equivalent time series. Indices of goodness of fit such as Kling-Gupta Efficiency, Index of Agreement and Percentage Bias are computed. Secondly, the representativeness of the model parameters in different locations is discussed. Finally a raster mode application is performed: snow water equilvalent maps on the whole Cache la Poudre river are computed. In all the applications the model performance are satisfactory in term of goodness of fitting measured snow water equivalent time series. The integration of the model in the NewAge-JGrass system allows the used to o enjoy all the component of the system: input data computation, output maps visualizetion in the GIS JGrass, model parameters automatic calibration.

  15. Rotating Stellar Models Can Account for the Extended Main Sequence Turnoffs in Intermediate Age Clusters

    CERN Document Server

    Brandt, Timothy D

    2015-01-01

    We show that the extended main sequence turnoffs seen in intermediate age Large Magellanic Cloud (LMC) clusters, often attributed to age spreads of several hundred Myr, may be easily accounted for by variable stellar rotation in a coeval population. We compute synthetic photometry for grids of rotating stellar evolution models and interpolate them to produce isochrones at a variety of rotation rates and orientations. An extended main sequence turnoff naturally appears in color-magnitude diagrams at ages just under 1 Gyr, peaks in extent between ~1 and 1.5 Gyr, and gradually disappears at around 2 Gyr in age. We then fit our interpolated isochrones by eye to four LMC clusters with very extended main sequence turnoffs: NGC 1783, 1806, 1846, and 1987. In each case, stellar populations with a single age and metallicity can comfortably account for the observed extent of the turnoff region.

  16. 3DAP analysis of phosphorus segregation for thermal aged model RPV steel

    International Nuclear Information System (INIS)

    Phosphorus segregation in thermal aged nuclear reactor model pressure vessel (RPV) steels was investigated by three dimensional atom probe (3DAP). The model steel containing less Mn, Ni, Mo and different P compared to A508-Ⅲ was prepared by vacuum induction melting. After the initial heart treatment at 880℃-0.5 h and water quenching, the specimens were aged at 400℃ for up to 500 h. The results show that phosphorus segregated to the carbide/matrix interface in both containing lower phosphorus and higher phosphorus specimens. A precipitate containing phosphorus, silicon and carbon, with a thickness of about 20 nm, formed in the specimens aged for 150 h in specimen containing higher phosphorus. With the extension of ageing time, phosphorus and silicon segregated and formed a thin layer at the boundaries of Fe3C. The silicon segregation baffled the growth of Fe3C. (authors)

  17. Lithium-ion Open Circuit Voltage (OCV) curve modelling and its ageing adjustment

    Science.gov (United States)

    Lavigne, L.; Sabatier, J.; Francisco, J. Mbala; Guillemard, F.; Noury, A.

    2016-08-01

    This paper is a contribution to lithium-ion batteries modelling taking into account aging effects. It first analyses the impact of aging on electrode stoichiometry and then on lithium-ion cell Open Circuit Voltage (OCV) curve. Through some hypotheses and an appropriate definition of the cell state of charge, it shows that each electrode equilibrium potential, but also the whole cell equilibrium potential can be modelled by a polynomial that requires only one adjustment parameter during aging. An adjustment algorithm, based on the idea that for two fixed OCVs, the state of charge between these two equilibrium states is unique for a given aging level, is then proposed. Its efficiency is evaluated on a battery pack constituted of four cells.

  18. Relation between Charpy impact properties and magnetism in thermally aged Fe-Cu model alloys

    International Nuclear Information System (INIS)

    This study demonstrates the possibility of applying magnetic methods to pressure vessel surveillance for irradiation embrittlement at nuclear power plants. Charpy impact test and magnetic hesteresis measurement were preformed on thermally aged Fe-1.0wt%Cu model alloys with and without pre-deformation. DBTT increased with increasing aging time. However, magnetic hysteresis parameters showed nonmonotonical changes. The phenomena are discussed in terms of Cu precipitation behavior and dislocation structure. (author)

  19. Age model of fertility in Vojvodina at the beginning of the 21st century

    OpenAIRE

    Veljović Radmila; Paunović Dragana

    2014-01-01

    This paper presents an outlook on fertility trends of the population of Vojvodina in the first decade of the 21st century, a period that includes the results of the previous two Censuses held in 2002 and 2011. The main concern is identifying determinants of this development process and the dynamics regarding the age model of fertility as well as the way it is manifested in Vojvodina. Methodology of this research relies on evaluating age specific rates, dete...

  20. Model systems to the rescue: The relationship between aging and innate immunity

    OpenAIRE

    Alper, Scott

    2010-01-01

    In humans, there is an interdependent relationship between aging and immune system function, with each process affecting the outcome of the other. Aging can trigger immune system dysfunction, and alterations in the immune response can in turn affect human lifespan. Genetic experiments in model organisms such as C. elegans and Drosophila have led to the identification of numerous genes and signaling pathways that can modulate organismal lifespan and immune system function. Importantly, many of...

  1. Spatially explicit estimation of forest age by integrating remotely sensed data and inverse yield modeling techniques

    OpenAIRE

    Frate L; Carranza ML; Garfì V; Febbraro MD; Tonti D; Marchetti M; Ottaviano M.; Santopuoli G; Chirici G

    2016-01-01

    In this work we present an innovative method based on the application of inverse yield models for producing spatially explicit estimations of forest age. Firstly, a raster growing stock volume map was produced using the non-parametric k-Nearest Neighbors estimation method on the basis of IRS LISS-III remotely sensed imagery and field data collected in the framework of a local forest inventory. Secondly, species specific inverted yield equations were applied to estimate forest age as a functio...

  2. Antioxidant effect of garlic and aged black garlic in animal model of type 2 diabetes mellitus

    OpenAIRE

    Lee, Young-Min; Gweon, Oh-Cheon; Seo, Yeong-Ju; Im, Jieun; Kang, Min-Jung; Kim, Myo-Jeong; Kim, Jung-In

    2009-01-01

    Hyperglycemia in the diabetic state increases oxidative stress and antioxidant therapy can be strongly correlated with decreased risks for diabetic complications. The purpose of this study is to determine antioxidant effect of garlic and aged black garlic in animal model of type 2 diabetes. The antioxidant activity of garlic and aged black garlic was measured as the activity in scavenging free radicals by the trolox equivalent antioxidant capacity (TEAC) assay. Three week-old db/db mice were ...

  3. Moringa oleifera Mitigates Memory Impairment and Neurodegeneration in Animal Model of Age-Related Dementia

    OpenAIRE

    Chatchada Sutalangka; Jintanaporn Wattanathorn; Supaporn Muchimapura; Wipawee Thukham-mee

    2013-01-01

    To date, the preventive strategy against dementia is still essential due to the rapid growth of its prevalence and the limited therapeutic efficacy. Based on the crucial role of oxidative stress in age-related dementia and the antioxidant and nootropic activities of Moringa oleifera, the enhancement of spatial memory and neuroprotection of M. oleifera leaves extract in animal model of age-related dementia was determined. The possible underlying mechanism was also investigated. Male Wistar rat...

  4. Stability results on age-structured SIS epidemic model with coupling impulsive effect

    Directory of Open Access Journals (Sweden)

    Guangtian Zhu

    2006-02-01

    Full Text Available We develop an age-structured epidemic model for malaria with impulsive effect, and consider the effect of blood transfusion and infected-vector transmission. Transmission rates depend on age. We derive the condition in which eradication solution is locally asymptotically stable. The condition shows that large enough pulse reducing proportion and relatively small interpulse time lead to the eradication of the diseases.

  5. Deterministic models of groundwater age, life expectancy and transit time distributions in advective-dispersive systems

    OpenAIRE

    Cornaton, Fabien; Perrochet, Pierre

    2004-01-01

    The main objective of this dissertation consisted in the elaboration of a methodology to determine reservoir groundwater age, life expectancy, and transit time probability distributions in a deterministic manner, considering advective-dispersive transport in steady velocity fields. In the first section, it is shown that by modelling the statistical distribution of groundwater age at aquifer scale by means of the classical advection-dispersion equation (ADE) for a conservative and non-reactive...

  6. Analysis and Numerics for an Age- and Sex-Structured Population Model

    OpenAIRE

    Pokojovy, Michael; Skvarkovskyi, Yevhenii

    2014-01-01

    We study a linear model of McKendrick-von Foerster-Keyfitz type for the temporal development of the age structure of a two-sex human population. For the underlying system of partial integro-differential equations, we exploit the semigroup theory to show the classical well-posedness and asymptotic stability in a Hilbert space framework under appropriate conditions on the age-specific mortality and fertility moduli. Finally, we propose an implicit finite difference scheme to numerically solve t...

  7. Analysis of a general age-dependent vaccination model for a vertically transmitted disease

    International Nuclear Information System (INIS)

    A SIR epidemic model of a general age-dependent vaccination for a vertically as well as horizontally transmitted disease is investigated when the total population is time dependent, and fertility, mortality and removal rates depend on age. We establish the existence and the uniqueness of the solution and obtain the asymptotic behaviour for the solution. For the steady state solution a critical vaccination coverage which will eventually eradicate the disease is determined. (author). 18 refs

  8. Modeling variations of marine reservoir ages during the last 45 000 years

    Directory of Open Access Journals (Sweden)

    J. Franke

    2008-01-01

    Full Text Available When dating marine samples with 14C, the reservoir-age effect is usually assumed to be constant, although atmospheric 14C production rate and ocean circulation changes cause temporal and spatial reservoir-age variations. These lead to dating errors, which can limit the interpretation of cause and effect in paleoclimate data. We used a global ocean circulation model forced by transient atmospheric Δ14C variations to calculate reservoir ages for the last 45 000 years for a present day-like and a last glacial maximum-like ocean circulation. A ~30% reduced Atlantic meridonal overturning circulation leads to increased reservoir ages by up to ~500 years in high latitudes. Temporal variations are proportional to the absolute value of the reservoir age; regions with large reservoir age also show large variation. Temporal variations range between ~300 years in parts of the subtropics and ~1000 years in the Southern Ocean. For tropical regions, which are generally assumed to have nearly stable reservoir ages, the model suggests variations of several hundred years.

  9. Uncertainty and sensitivity analyses for age-dependent unavailability model integrating test and maintenance

    International Nuclear Information System (INIS)

    Highlights: ► Application of analytical unavailability model integrating T and M, ageing, and test strategy. ► Ageing data uncertainty propagation on system level assessed via Monte Carlo simulation. ► Uncertainty impact is growing with the extension of the surveillance test interval. ► Calculated system unavailability dependence on two different sensitivity study ageing databases. ► System unavailability sensitivity insights regarding specific groups of BEs as test intervals extend. - Abstract: The interest in operational lifetime extension of the existing nuclear power plants is growing. Consequently, plants life management programs, considering safety components ageing, are being developed and employed. Ageing represents a gradual degradation of the physical properties and functional performance of different components consequently implying their reduced availability. Analyses, which are being made in the direction of nuclear power plants lifetime extension are based upon components ageing management programs. On the other side, the large uncertainties of the ageing parameters as well as the uncertainties associated with most of the reliability data collections are widely acknowledged. This paper addresses the uncertainty and sensitivity analyses conducted utilizing a previously developed age-dependent unavailability model, integrating effects of test and maintenance activities, for a selected stand-by safety system in a nuclear power plant. The most important problem is the lack of data concerning the effects of ageing as well as the relatively high uncertainty associated to these data, which would correspond to more detailed modelling of ageing. A standard Monte Carlo simulation was coded for the purpose of this paper and utilized in the process of assessment of the component ageing parameters uncertainty propagation on system level. The obtained results from the uncertainty analysis indicate the extent to which the uncertainty of the selected

  10. Evidence of oxidative injury during aging of the liver in a mouse model.

    OpenAIRE

    Colantoni, Alessandra; Idilman, Ramazan; De Maria, Nicola; Duffner, Lisa A.; VAN THIEL, DAVID H.; Witte, Pamela L.; Kovacs, Elizabeth J.

    2001-01-01

    The aim of the present study was to determine whether oxidative stress contributes to aging of the liver in a mouse model. Liver was obtained from young (3–5 months old) and aged (18–24 months old) mice. No age-induced gross changes in liver morphology were detected by light microscopy. Apoptosis was measured using the fragment end labeling of DNA for the immunohistochemical identification of the apoptotic nuclei. The total apoptotic cells represented 1% of the total cells in livers of young ...

  11. Study and prediction model on low temperature aging embrittlement in duplex stainless steels

    International Nuclear Information System (INIS)

    Within the framework of a general study on low temperature (280-400 degree centigree) aging embrittlement in duplex stainless steels, a relationship has been obtained between aging, measured from ferrite hardness evolution, and bulk materials embrittlement, determined from fracture toughness and fracture impact tests. The existing correlation between the increase in ferrite hardness and its percentage presence in the fracture path supports this relationship and results in the development of a prediction design model which provides the fracture resistance curves, for any aging level, based on the chemical composition and the steel's properties in an unaged state. (Author)

  12. Apolipoprotein E allele-dependent pathogenesis: A model for age-related retinal degeneration

    OpenAIRE

    Malek, G; Johnson, L V; Mace, B E; Saloupis, P.; Schmechel, D E; Rickman, D. W.; Toth, C. A.; Sullivan, P. M.; Rickman, C. Bowes

    2005-01-01

    Age-related macular degeneration (AMD) is a late-onset, multifactorial, neurodegenerative disease of the retina and the leading cause of irreversible vision loss in the elderly in the Western world. We describe here a murine model that combines three known AMD risk factors: advanced age, high fat cholesterol-rich (HF-C) diet, and apolipoprotein E (apoE) genotype. Eyes of aged, targeted replacement mice expressing human apoE2, apoE3, or apoE4 and maintained on a HF-C diet show apoE isoform-dep...

  13. Observational Constraints on Interacting Model of New Agegraphic Dark Energy and Alleviation of Cosmic Age Problem

    CERN Document Server

    Li, Yun-He; Cui, Jing-Lei; Wang, Zhuo; Zhang, Xin

    2010-01-01

    Many dark energy models fail to pass the cosmic age test via the old quasar APM 08279+5255 at redshift $z=3.91$, even the $\\Lambda$CDM model and the holographic dark energy model are not exception. In this paper, we focus on the topic of age problem in the new agegraphic dark energy (NADE) model. We determine the age of the universe in the NADE model by using the fitting result of observational data including type Ia supernovae (SNIa), baryon acoustic oscillation (BAO) and cosmic microwave background (CMB). It is shown that the NADE model also faces the challenge of the age problem caused by the old quasar APM 08279+5255. In order to overcome such a difficulty, we consider the possible interaction between dark energy and matter. We show that the old quasar APM 08279+5255 at redshift $z=3.91$ can be successfully accommodated in the interacting new agegraphic dark energy (INADE) model at $2\\sigma$ level under the current observational constraints.

  14. A whole-body mathematical model of cholesterol metabolism and its age-associated dysregulation

    Directory of Open Access Journals (Sweden)

    Mc Auley Mark T

    2012-10-01

    Full Text Available Abstract Background Global demographic changes have stimulated marked interest in the process of aging. There has been, and will continue to be, an unrelenting rise in the number of the oldest old ( >85 years of age. Together with an ageing population there comes an increase in the prevalence of age related disease. Of the diseases of ageing, cardiovascular disease (CVD has by far the highest prevalence. It is regarded that a finely tuned lipid profile may help to prevent CVD as there is a long established relationship between alterations to lipid metabolism and CVD risk. In fact elevated plasma cholesterol, particularly Low Density Lipoprotein Cholesterol (LDL-C has consistently stood out as a risk factor for having a cardiovascular event. Moreover it is widely acknowledged that LDL-C may rise with age in both sexes in a wide variety of groups. The aim of this work was to use a whole-body mathematical model to investigate why LDL-C rises with age, and to test the hypothesis that mechanistic changes to cholesterol absorption and LDL-C removal from the plasma are responsible for the rise. The whole-body mechanistic nature of the model differs from previous models of cholesterol metabolism which have either focused on intracellular cholesterol homeostasis or have concentrated on an isolated area of lipoprotein dynamics. The model integrates both current and previously published data relating to molecular biology, physiology, ageing and nutrition in an integrated fashion. Results The model was used to test the hypothesis that alterations to the rate of cholesterol absorption and changes to the rate of removal of LDL-C from the plasma are integral to understanding why LDL-C rises with age. The model demonstrates that increasing the rate of intestinal cholesterol absorption from 50% to 80% by age 65 years can result in an increase of LDL-C by as much as 34 mg/dL in a hypothetical male subject. The model also shows that decreasing the rate of hepatic

  15. Individual Human Capitals, Collective Behavior, and Age-Earnings Profiles of Workers: an Alternative Rationale and New Path to Modeling.

    OpenAIRE

    Maximov, Serguei

    2011-01-01

    In the article, an improved macro-level model is presented. The improvement concerns statistic averaging -- more reasonable distribution (Weibull) of individual "social" ages at intertemporal decision-making is used to get the macro-model. Simple (linear) regression based on the macro-model's specification is used to fit large samples (more than 40 age points) of empirical age-earnings data (UK, 2002; Canada, 1973, 1984, 1994). The found estimates of the pre-supposed "social" ages of persons ...

  16. Evaluation of Aged Garlic Extract Neuroprotective Effect in a Focal Model of Cerebral Ischemia

    Science.gov (United States)

    Aguilera, Penélope; Maldonado, Perla D.; Ortiz-Plata, Alma; Barrera, Diana; Chánez-Cárdenas, María Elena

    2008-02-01

    The oxidant species generated in cerebral ischemia have been implicated as important mediators of neuronal injury through damage to lipids, DNA, and proteins. Since ischemia as well as reperfusion insults generate oxidative stress, the administration of antioxidants may limit oxidative damage and ameliorate disease progression. The present work shows the transitory neuroprotective effect of the aged garlic extract (AGE) administration (a proposed antioxidant compound) in a middle cerebral artery occlusion (MCAO) model in rats and established its therapeutic window. To determine the optimal time of administration, animal received AGE (1.2 mL/kg) intraperitoneally 30 min before onset of reperfusion (-0.5 R), at the beginning of reperfusion (0R), or 1 h after onset of reperfusion (1R). Additional doses were administrated after 1, 2, or 3 h after onset of reperfusion. To establish the therapeutic window of AGE, the infarct area was determined for each treatment after different times of reperfusion. Results show that the administration of AGE at the onset of reperfusion reduced the infarct area by 70% (evaluated after 2 h reperfusion). The therapeutic window of AGE was determined. Repeated doses did not extend the temporal window of protection. A significant reduction in the nitrotyrosine level was observed in the brain tissue subjected to MCAO after AGE treatment at the onset of reperfusion. Data in the present work show that AGE exerts a transitory neuroprotective effect in response to ischemia/reperfusion-induced neuronal injury.

  17. Asteroid age distributions determined by space weathering and collisional evolution models

    CERN Document Server

    Willman, Mark; 10.1016/j.icarus.2010.02.017

    2010-01-01

    We provide evidence of consistency between the dynamical evolution of main belt asteroids and their color evolution due to space weathering. The dynamical age of an asteroid's surface \\citep{bib.bot05a,bib.nes05} is the time since its last catastrophic disruption event which is a function of the object's diameter. The age of an S-complex asteroid's surface may also be determined from its color using a space weathering model \\citep[e.g.][]{bib.wil10,bib.jed04,bib.wil08,bib.mar06}. We used a sample of 95 S-complex asteroids from SMASS and obtained their absolute magnitudes and $u,g,r,i,z$ filter magnitudes from SDSS. The absolute magnitudes yield a size-derived age distribution. The $u,g,r,i,z$ filter magnitudes lead to the principal component color which yields a color-derived age distribution by inverting our color-age relationship, an enhanced version of the `dual $\\tau$' space weathering model of \\citet{bib.wil10}. We fit the size-age distribution to the enhanced dual $\\tau$ model and found characteristic w...

  18. The development of an age-structured model for trachoma transmission dynamics, pathogenesis and control.

    Directory of Open Access Journals (Sweden)

    Manoj Gambhir

    Full Text Available BACKGROUND: Trachoma, the worldwide leading infectious cause of blindness, is due to repeated conjunctival infection with Chlamydia trachomatis. The effects of control interventions on population levels of infection and active disease can be promptly measured, but the effects on severe ocular sequelae require long-term monitoring. We present an age-structured mathematical model of trachoma transmission and disease to predict the impact of interventions on the prevalence of blinding trachoma. METHODOLOGY/PRINCIPAL FINDINGS: The model is based on the concept of multiple reinfections leading to progressive conjunctival scarring, trichiasis, corneal opacity and blindness. It also includes aspects of trachoma natural history, such as an increasing rate of recovery from infection and a decreasing chlamydial load with subsequent infections that depend upon a (presumed acquired immunity that clears infection with age more rapidly. Parameters were estimated using maximum likelihood by fitting the model to pre-control infection prevalence data from hypo-, meso- and hyperendemic communities from The Gambia and Tanzania. The model reproduces key features of trachoma epidemiology: 1 the age-profile of infection prevalence, which increases to a peak at very young ages and declines at older ages; 2 a shift in this prevalence peak, toward younger ages in higher force of infection environments; 3 a raised overall profile of infection prevalence with higher force of infection; and 4 a rising profile, with age, of the prevalence of the ensuing severe sequelae (trachomatous scarring, trichiasis, as well as estimates of the number of infections that need to occur before these sequelae appear. CONCLUSIONS/SIGNIFICANCE: We present a framework that is sufficiently comprehensive to examine the outcomes of the A (antibiotic component of the SAFE strategy on disease. The suitability of the model for representing population-level patterns of infection and disease sequelae

  19. Building from a conceptual model of the resilience process during ageing, towards the Groningen Aging Resilience Inventory

    NARCIS (Netherlands)

    van Abbema, Renske; Bielderman, Annemiek; De Greef, Mathieu; Hobbelen, Hans; Krijnen, Wim; van der Schans, Cees

    2015-01-01

    Aim. To develop and psychometrically test the Groningen Ageing Resilience Inventory. Background. Ageing is a process that is often accompanied by functional limitation, disabilities and losses. Instead of focusing on these negative events of ageing, there are opportunities in focusing on adaptation

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

    Science.gov (United States)

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

    2013-12-01

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

  1. Prediction of Age at Menopause in Women of Suburban Areas in Chennai Using A Model of Fsh Over Age - A Pilot Study

    Directory of Open Access Journals (Sweden)

    SM Priyadharshini

    2014-02-01

    Full Text Available Objectives: The human ovary is characterized by early senescence and the end stage of ovarian activity is termed menopause. The age at which menopause occur is between 45 and 55 years world wide. The objective of this pilot study is to determine the age at menopause by using a model of FSH over age in women of sub urban region around Chennai, India. Materials and Methods: The subjects include 500 patients of age between 30 and 36 yrs with BMI ranging from 24-28.After recording their general profile and history, blood samples were obtained by venipuncture and hormone FSH was estimated on the day 3 of the menstrual cycle. Based on functional dependence of FSH in the form of exponential relation with age, a model was proposed. Using least square approximation the beta values were calculated. Results: With the help of beta values and using the cut off value of 40 IU/ml for FSH, this predicted model determined the age of menopause as 44.6yrs in women of sub urban region around Chennai. Conclusion: The age of menopause is different in various region worlds wide. According to this pilot study the suburban women of Chennai, attain menopause at an age of 44.6 years. Further exploration should be done to alleviate the role of diet, life style and ethnic variation on menopausal age and the impact of chronic disease like osteoporosis during the period of menopause.

  2. Nrf2 Signaling and the Slowed Aging Phenotype: Evidence from Long-Lived Models

    Directory of Open Access Journals (Sweden)

    Danielle R. Bruns

    2015-01-01

    Full Text Available Studying long-lived animals provides novel insight into shared characteristics of aging and represents a unique model to elucidate approaches to prevent chronic disease. Oxidant stress underlies many chronic diseases and resistance to stress is a potential mechanism governing slowed aging. The transcription factor nuclear factor (erythroid-derived 2-like 2 is the “master regulator” of cellular antioxidant defenses. Nrf2 is upregulated by some longevity promoting interventions and may play a role in regulating species longevity. However, Nrf2 expression and activity in long-lived models have not been well described. Here, we review evidence for altered Nrf2 signaling in a variety of slowed aging models that accomplish lifespan extension via pharmacological, nutritional, evolutionary, genetic, and presumably epigenetic means.

  3. Aging and percolation dynamics in a Non-Poissonian temporal network model

    CERN Document Server

    Moinet, Antoine; Pastor-Satorras, Romualdo

    2016-01-01

    We present an exhaustive mathematical analysis of the recently proposed Non-Poissonian Ac- tivity Driven (NoPAD) model [Moinet et al. Phys. Rev. Lett., 114 (2015)], a temporal network model incorporating the empirically observed bursty nature of social interactions. We focus on the aging effects emerging from the Non-Poissonian dynamics of link activation, and on their effects on the topological properties of time-integrated networks, such as the degree distribution. Analytic expressions for the degree distribution of integrated networks as a function of time are derived, ex- ploring both limits of vanishing and strong aging. We also address the percolation process occurring on these temporal networks, by computing the threshold for the emergence of a giant connected component, highlighting the aging dependence. Our analytic predictions are checked by means of extensive numerical simulations of the NoPAD model.

  4. A validated age-related normative model for male total testosterone shows increasing variance but no decline after age 40 years.

    Science.gov (United States)

    Kelsey, Thomas W; Li, Lucy Q; Mitchell, Rod T; Whelan, Ashley; Anderson, Richard A; Wallace, W Hamish B

    2014-01-01

    The diagnosis of hypogonadism in human males includes identification of low serum testosterone levels, and hence there is an underlying assumption that normal ranges of testosterone for the healthy population are known for all ages. However, to our knowledge, no such reference model exists in the literature, and hence the availability of an applicable biochemical reference range would be helpful for the clinical assessment of hypogonadal men. In this study, using model selection and validation analysis of data identified and extracted from thirteen studies, we derive and validate a normative model of total testosterone across the lifespan in healthy men. We show that total testosterone peaks [mean (2.5-97.5 percentile)] at 15.4 (7.2-31.1) nmol/L at an average age of 19 years, and falls in the average case [mean (2.5-97.5 percentile)] to 13.0 (6.6-25.3) nmol/L by age 40 years, but we find no evidence for a further fall in mean total testosterone with increasing age through to old age. However we do show that there is an increased variation in total testosterone levels with advancing age after age 40 years. This model provides the age related reference ranges needed to support research and clinical decision making in males who have symptoms that may be due to hypogonadism. PMID:25295520

  5. A Proactive Aging/Asset Management Model to Optimize Equipment Maintenance Resources Over Plant Lifetime

    International Nuclear Information System (INIS)

    Experience has shown that proactive aging/asset management can best be defined as an ongoing process. Station goals directly supported by such a process include reducing Unplanned Capability Loss Factor and gaining the optimum value from maintenance and aging management budgets. An effective aging/asset management process must meet evolving and sometimes conflicting requirements for efficient and reliable nuclear power plant operation. The process should identify most likely contributors before they fail, and develop cost-effective contingencies. Current trends indicate the need for focused tools that give quantitative input to decision-making. Opposing goals, such as increasing availability while optimizing aging management budgets, must be balanced. Recognizing the importance of experience in reducing the uncertainty inherent in predicting equipment degradation rates, nuclear industry demographics suggest the need to capture existing expert knowledge in a usable form. The Proactive Aging/Asset Management Process has been developed to address these needs. The proactive approach is a process supported by tools. The process identifies goals and develops criteria - including safety, costs, and power production - that are used to prioritize systems and equipment across the plant. The process then draws upon tools to most effectively meet the plant's goals. The Proactive Aging/Asset Management ModelTM is one software-enabled tool designed for mathematical optimization. Results assist a plant in developing a plant-wide plan of aging management activities. This paper describes the proactive aging/asset management process and provides an overview of the methodology that has been incorporated in a model to perform a plant-wide optimization of aging management activities. (authors)

  6. Aging and serum MCP-1 are associated with gut microbiome composition in a murine model.

    Science.gov (United States)

    Conley, Melissa N; Wong, Carmen P; Duyck, Kyle M; Hord, Norman; Ho, Emily; Sharpton, Thomas J

    2016-01-01

    Introduction. Age is the primary risk factor for major human chronic diseases, including cardiovascular disorders, cancer, type 2 diabetes, and neurodegenerative diseases. Chronic, low-grade, systemic inflammation is associated with aging and the progression of immunosenescence. Immunosenescence may play an important role in the development of age-related chronic disease and the widely observed phenomenon of increased production of inflammatory mediators that accompany this process, referred to as "inflammaging." While it has been demonstrated that the gut microbiome and immune system interact, the relationship between the gut microbiome and age remains to be clearly defined, particularly in the context of inflammation. The aim of our study was to clarify the associations between age, the gut microbiome, and pro-inflammatory marker serum MCP-1 in a C57BL/6 murine model. Results. We used 16S rRNA gene sequencing to profile the composition of fecal microbiota associated with young and aged mice. Our analysis identified an association between microbiome structure and mouse age and revealed specific groups of taxa whose abundances stratify young and aged mice. This includes the Ruminococcaceae, Clostridiaceae, and Enterobacteriaceae. We also profiled pro-inflammatory serum MCP-1 levels of each mouse and found that aged mice exhibited elevated serum MCP-1, a phenotype consistent with inflammaging. Robust correlation tests identified several taxa whose abundance in the microbiome associates with serum MCP-1 status, indicating that they may interact with the mouse immune system. We find that taxonomically similar organisms can exhibit differing, even opposite, patterns of association with the host immune system. We also find that many of the OTUs that associate with serum MCP-1 stratify individuals by age. Discussion. Our results demonstrate that gut microbiome composition is associated with age and the pro-inflammatory marker, serum MCP-1. The correlation between age

  7. Ovarian Aging-Like Phenotype in the Hyperandrogenism-Induced Murine Model of Polycystic Ovary

    Directory of Open Access Journals (Sweden)

    Mohammad Amin Rezvanfar

    2014-01-01

    Full Text Available There are prominently similar symptoms, effectors, and commonalities in the majority of characteristics between ovarian aging and polycystic ovarian syndrome (PCOS. Despite the approved role of oxidative stress in the pathogenesis of PCOS and aging, to our knowledge, the link between the PCO(S and aging has not been investigated yet. In this study we investigated the possible exhibition of ovarian aging phenotype in murine model of PCO induced by daily oral administration of letrozole (1 mg/kg body weight for 21 consecutive days in the female Wistar rats. Hyperandrogenization showed irregular cycles and histopathological characteristics of PCO which was associated with a significant increase in lipid peroxidation (LPO and reactive oxygen species (ROS and decrease in total antioxidant capacity (TAC in serum and ovary. Moreover, serum testosterone, insulin and tumor necrosis factor-alpha (TNF-α levels, and ovarian matrix metalloproteinase-2 (MMP-2 were increased in PCO rats compared with healthy controls, while estradiol and progesterone diminished. Almost all of these findings are interestingly found to be common with the characteristics identified with (ovarian aging showing that hyperandrogenism-induced PCO in rat is associated with ovarian aging-like phenotypes. To our knowledge, this is the first report that provides evidence regarding the phenomenon of aging in PCO.

  8. Ageing effects modelling in probabilistic safety assessment of nuclear power plants

    International Nuclear Information System (INIS)

    Ageing management has become a major concern for many responsible organizations during the last years, because as the operating power plants have got older, they may have the tendency to become less safe. The effects of age-related degradation of plant components, systems and structures are necessary to be assessed in order to assure a continuous safe operation of nuclear power plants. The Probabilistic Safety Analysis (PSA) is an efficient system analysis method which is used to assess the risk of operation of nuclear power plants. In the assessment of risk level for a plant, most of the PSA studies generally didn't take into account the ageing effects, and uses a time averaged unavailability. By incorporation of ageing effects, the results enable an identification of the components that have the greatest effect on risk if their failure rates increase due to ageing effects modelling. In this paper, it was assessed the impact on Class IV Electrical Power System unavailability of the assumed increase in components failure probability caused by components ageing. The electrical system was chosen for the study because there are a lot of cables and for these types of equipment there is no planned preventive or corrective maintenance, and they are originally designed to reach the end of plant life with an adequate safety margin. To quantify the effects of age-related degradation on components, the linear ageing model was used. In this model, the failure rate of a component λ (t) is expressed as a sum of two independent failure rates, one associated with random failure, λ0, and the other associated with failures due to aging α, so: λ(t) = λ0 + αt. The basic events were coded using a computer code similar to CAFTA, developed in INR Pitesti. For the reliability data allocation for basic events a intern data base was used. This data base contains data from the following generic data bases: IAEA Component Reliability Data for use in PSA, Point Lepreau Component

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

    Science.gov (United States)

    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.

  10. Analysis of an Age Structured SEIRS Epidemic Model with Varying Total Population Size and Vaccination

    Institute of Scientific and Technical Information of China (English)

    Xue-Zhi Li; Geni Gupur; Guang-Tian Zhu

    2004-01-01

    This article focuses on the study of an age structured SEIRS epidemic model with a vaccination program when the total population size is not kept at constant. We first give the explicit expression of the reproduction number R((ψ),(λ))in the presence of vaccine((λ))is the exponent of growth of total population), and show that the infection-free steady state is linearly stable if R ((ψ),(λ))1, then we apply the theoretical results to vaccination policies to determine the optimal age or ages at which an individual should be vaccinated. It is shown that the optimal strategy can be either one-or two-age strategies.

  11. Age estimation based on pelvic ossification using regression models from conventional radiography.

    Science.gov (United States)

    Zhang, Kui; Dong, Xiao-Ai; Fan, Fei; Deng, Zhen-Hua

    2016-07-01

    To establish regression models for age estimation from the combination of the ossification of iliac crest and ischial tuberosity. One thousand three hundred and seventy-nine conventional pelvic radiographs at the West China Hospital of Sichuan University between January 2010 and June 2012 were evaluated retrospectively. The receiver operating characteristic analysis was performed to measure the value of estimation of 18 years of age with the classification scheme for the iliac crest and ischial tuberosity. Regression analysis was performed, and formulas for calculating approximate chronological age according to the combination developmental status of the ossification for the iliac crest and ischial tuberosity were developed. The areas under the receiver operating characteristic (ROC) curves were above 0.9 (p systems, and the cubic regression model was found to have the highest R-square value (R (2) = 0.744 for female and R (2) = 0.753 for male). The present classification scheme for apophyseal iliac crest ossification and the ischial tuberosity may be used for age estimation. And the present established cubic regression model according to the combination developmental status of the ossification for the iliac crest and ischial tuberosity can be used for age estimation. PMID:27169673

  12. Eclipsing Binary Stars as Tests of Stellar Evolutionary Models and Stellar Ages

    CERN Document Server

    Stassun, Keivan G; Lopez-Morales, Mercedes; Prsa, Andrej

    2009-01-01

    Eclipsing binary stars provide highly accurate measurements of the fundamental physical properties of stars. They therefore serve as stringent tests of the predictions of evolutionary models upon which most stellar age determinations are based. Models generally perform very well in predicting coeval ages for eclipsing binaries with main-sequence components more massive than ~1.2 Msun; relative ages are good to ~5% or better in this mass regime. Low-mass main-sequence stars (M < 0.8 Msun) reveal large discrepancies in the model predicted ages, primarily due to magnetic activity in the observed stars that appears to inhibit convection and likely causes the radii to be 10-20% larger than predicted. In mass-radius diagrams these stars thus appear 50-90% older or younger than they really are. Aside from these activity-related effects, low-mass pre--main-sequence stars at ages ~1 Myr can also show non-coevality of ~30% due to star formation effects, however these effects are largely erased after ~10 Myr.

  13. Structured additive regression modeling of age of menarche and menopause in a breast cancer screening program.

    Science.gov (United States)

    Duarte, Elisa; de Sousa, Bruno; Cadarso-Suarez, Carmen; Rodrigues, Vitor; Kneib, Thomas

    2014-05-01

    Breast cancer risk is believed to be associated with several reproductive factors, such as early menarche and late menopause. This study is based on the registries of the first time a woman enters the screening program, and presents a spatio-temporal analysis of the variables age of menarche and age of menopause along with other reproductive and socioeconomic factors. The database was provided by the Portuguese Cancer League (LPCC), a private nonprofit organization dealing with multiple issues related to oncology of which the Breast Cancer Screening Program is one of its main activities. The registry consists of 259,652 records of women who entered the screening program for the first time between 1990 and 2007 (45-69-year age group). Structured Additive Regression (STAR) models were used to explore spatial and temporal correlations with a wide range of covariates. These models are flexible enough to deal with a variety of complex datasets, allowing us to reveal possible relationships among the variables considered in this study. The analysis shows that early menarche occurs in younger women and in municipalities located in the interior of central Portugal. Women living in inland municipalities register later ages for menopause, and those born in central Portugal after 1933 show a decreasing trend in the age of menopause. Younger ages of menarche and late menopause are observed in municipalities with a higher purchasing power index. The analysis performed in this study portrays the time evolution of the age of menarche and age of menopause and their spatial characterization, adding to the identification of factors that could be of the utmost importance in future breast cancer incidence research. PMID:24615881

  14. Anti-apoptotic treatment in mouse models of age-related hearing loss

    Institute of Scientific and Technical Information of China (English)

    Fengchan Han; Oumei Wang; Quanxiang Cai

    2016-01-01

    Age-related hearing loss (AHL), or presbycusis, is the most common neurodegenerative disorder and top communication deficit of the aged population. Genetic predisposition is one of the major factors in the development of AHL. Generally, AHL is associated with an age-dependent loss of sensory hair cells, spiral ganglion neurons and stria vascularis cells in the inner ear. Although the mechanisms leading to genetic hearing loss are not completely understood, caspase-family proteases function as important signals in the inner ear pathology. It is now accepted that mouse models are the best tools to study the mechanism of genetic hearing loss or AHL. Here, we provide a brief review of recent studies on hearing improvement in mouse models of AHL by anti-apoptotic treatment.

  15. Arterial pulse pressure amplification described by means of a nonlinear wave model: characterization of human aging

    Science.gov (United States)

    Alfonso, M.; Cymberknop, L.; Armentano, R.; Pessana, F.; Wray, S.; Legnani, W.

    2016-04-01

    The representation of blood pressure pulse as a combination of solitons captures many of the phenomena observed during its propagation along the systemic circulation. The aim of this work is to analyze the applicability of a compartmental model for propagation regarding the pressure pulse amplification associated with arterial aging. The model was applied to blood pressure waveforms that were synthesized using solitons, and then validated by waveforms obtained from individuals from differentiated age groups. Morphological changes were verified in the blood pressure waveform as a consequence of the aging process (i.e. due to the increase in arterial stiffness). These changes are the result of both a nonlinear interaction and the phenomena present in the propagation of nonlinear mechanic waves.

  16. Age of high redshift objects-a litmus test for the dark energy models

    International Nuclear Information System (INIS)

    The discovery of the quasar, the APM 08279+5255 at z=3.91 whose age is 2-3 Gyr has once again led to 'age crisis'. The noticeable fact about this object is that it cannot be accommodated in a universe with Ωm=0.27, currently accepted value of matter density parameter and ω=const. In this work, we explore the concordance of various dark energy parameterizations (w(z) models) with the age estimates of the old high redshift objects. It is alarming to note that the quasar cannot be accommodated in any dark energy model even for Ωm=0.23, which corresponds to 1σ deviation below the best fit value provided by WMAP. There is a need to look for alternative cosmologies or some other dark energy parameterizations which allow the existence of the high redshift objects

  17. Modelling of colour change induced by aging and heat treatment by using the multi-process kinetic analysis

    OpenAIRE

    Matsuo, Miyuki; Gril, Joseph; Yokoyama, Misao; Umemura, Kenji; Kawai, Shuichi

    2011-01-01

    Colour of wood changes both during natural aging and during heat treatment. Colour measuring, which is non-destructive and requires only a small area, might be an useful tool as an aging or deterioration index. Exact modelling of colour changes is important not only to predict deterioration but also to understand the aging and deterioration mechanism of wood. This study deals with the modelling of colour changes that occur both during natural aging and during heat treatment by using kinetic a...

  18. New Perspectives on Rodent Models of Advanced Paternal Age: Relevance to Autism

    Directory of Open Access Journals (Sweden)

    Claire J Foldi

    2011-06-01

    Full Text Available Offspring of older fathers have an increased risk of various adverse health outcomes, including autism and schizophrenia. With respect to biological mechanisms for this association, there are many more germline cell divisions in the life history of a sperm relative to that of an oocyte. This leads to more opportunities for copy error mutations in germ cells from older fathers. Evidence also suggests that epigenetic patterning in the sperm from older men is altered. Rodent models provide an experimental platform to examine the association between paternal age and brain development. Several rodent models of advanced paternal age (APA have been published with relevance to intermediate phenotypes related to autism. All four published APA models vary in key features creating a lack of consistency with respect to behavioural phenotypes. A consideration of common phenotypes that emerge from these APA-related mouse models may be informative in the exploration of the molecular and neurobiological correlates of APA.

  19. Ageing behaviour of electrochemical double layer capacitors. Part II. Lifetime simulation model for dynamic applications

    Energy Technology Data Exchange (ETDEWEB)

    Bohlen, Oliver; Kowal, Julia; Dirk Uwe Sauer [Institute for Power Electronics and Electrical Drives ISEA, RWTH Aachen University, Aachen (Germany)

    2007-11-08

    Based on the results of the experimental study in Part I, a holistic simulation model that combines electrical and thermal simulation of electrochemical double-layer capacitor (EDLC) modules with an ageing model is presented. This simulation model allows analysing self-accelerating degradation effects caused by elevated voltages and temperatures. Furthermore, the divergence of cell performance in a stack of cells can be investigated which makes the model a valuable tool for cell and stack design as well as for testing operating strategies and cooling systems. (author)

  20. Logistic regression models for polymorphic and antagonistic pleiotropic gene action on human aging and longevity

    DEFF Research Database (Denmark)

    Tan, Qihua; Bathum, L; Christiansen, L;

    2003-01-01

    In this paper, we apply logistic regression models to measure genetic association with human survival for highly polymorphic and pleiotropic genes. By modelling genotype frequency as a function of age, we introduce a logistic regression model with polytomous responses to handle the polymorphic...... situation. Genotype and allele-based parameterization can be used to investigate the modes of gene action and to reduce the number of parameters, so that the power is increased while the amount of multiple testing minimized. A binomial logistic regression model with fractional polynomials is used to capture...

  1. Infant bone age estimation based on fibular shaft length: model development and clinical validation

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, Andy; Stamoulis, Catherine; Bixby, Sarah D.; Breen, Micheal A.; Connolly, Susan A.; Kleinman, Paul K. [Boston Children' s Hospital, Harvard Medical School, Department of Radiology, Boston, MA (United States)

    2016-03-15

    Bone age in infants (<1 year old) is generally estimated using hand/wrist or knee radiographs, or by counting ossification centers. The accuracy and reproducibility of these techniques are largely unknown. To develop and validate an infant bone age estimation technique using fibular shaft length and compare it to conventional methods. We retrospectively reviewed negative skeletal surveys of 247 term-born low-risk-of-abuse infants (no persistent child protection team concerns) from July 2005 to February 2013, and randomized them into two datasets: (1) model development (n = 123) and (2) model testing (n = 124). Three pediatric radiologists measured all fibular shaft lengths. An ordinary linear regression model was fitted to dataset 1, and the model was evaluated using dataset 2. Readers also estimated infant bone ages in dataset 2 using (1) the hemiskeleton method of Sontag, (2) the hemiskeleton method of Elgenmark, (3) the hand/wrist atlas of Greulich and Pyle, and (4) the knee atlas of Pyle and Hoerr. For validation, we selected lower-extremity radiographs of 114 normal infants with no suspicion of abuse. Readers measured the fibulas and also estimated bone ages using the knee atlas. Bone age estimates from the proposed method were compared to the other methods. The proposed method outperformed all other methods in accuracy and reproducibility. Its accuracy was similar for the testing and validating datasets, with root-mean-square error of 36 days and 37 days; mean absolute error of 28 days and 31 days; and error variability of 22 days and 20 days, respectively. This study provides strong support for an infant bone age estimation technique based on fibular shaft length as a more accurate alternative to conventional methods. (orig.)

  2. Cyclostratigraphy for Chinese red clay sequences: Implications to changing previous age models and paleoclimate interpretations

    Science.gov (United States)

    Anwar, T.; Kravchinsky, V. A.; Zhang, R.

    2015-12-01

    The Chinese Loess Plateau contains red clay sequence which has continuous alternation of sedimentary cycles with recurrent paleoclimatic fluctuations. Absence of abundant fossils and inability of radiometric dating method made magnetostratigraphy a leading method to build age model for the red clay. Here magnetostratigraphic age model in red clay sequence is tested using cyclostratigraphy as orbital parameters of Earth are known. Milankovitch periodicities recorded in magnetic susceptibility and grain size in the Shilou red clay section are investigated and previously found age of 11 Ma for this section is re-evaluated. Magnetostratigraphy dating based on only visual correlation could potentially lead to erroneous age model. In this study the correlation is executed through the iteration procedure until it is supported by cyclostratigraphy; i.e. Milankovitch cycles are resolved in the best possible manner. Our new approach provides an age of 5.2 Ma for the Shilou profile. Wavelet analysis reveals that a 400 kyr eccentricity cycle is well preserved and the existence of a 100 kyr eccentricity in the red clay sequence on the eastern Chinese Loess Plateau suggests that eccentricity plays a vital role in Pliocene climate evolution. Paleomonsoon evolution is reconstructed and divided into three intervals (5.2-4.5 Ma, 4.5-3.6 Ma and 3.6-2.58 Ma). The earliest stage indicates that summer and winter monsoon cycles may rapidly alter, whereas the middle stage reflects an intensification of winter monsoon and aridification in Asia, and the youngest stage is characterized by relatively intensified summer monsoon. This study demonstrates that cyclostratigraphy can greatly assist magnetostratigraphy in dating the red clay sequences, and implies that many published age models for the red clay sequences should likely be re-assessed where possible. An evaluation of the monsoon system and climate change in eastern Asia might prominently benefit from this approach.

  3. Infant bone age estimation based on fibular shaft length: model development and clinical validation

    International Nuclear Information System (INIS)

    Bone age in infants (<1 year old) is generally estimated using hand/wrist or knee radiographs, or by counting ossification centers. The accuracy and reproducibility of these techniques are largely unknown. To develop and validate an infant bone age estimation technique using fibular shaft length and compare it to conventional methods. We retrospectively reviewed negative skeletal surveys of 247 term-born low-risk-of-abuse infants (no persistent child protection team concerns) from July 2005 to February 2013, and randomized them into two datasets: (1) model development (n = 123) and (2) model testing (n = 124). Three pediatric radiologists measured all fibular shaft lengths. An ordinary linear regression model was fitted to dataset 1, and the model was evaluated using dataset 2. Readers also estimated infant bone ages in dataset 2 using (1) the hemiskeleton method of Sontag, (2) the hemiskeleton method of Elgenmark, (3) the hand/wrist atlas of Greulich and Pyle, and (4) the knee atlas of Pyle and Hoerr. For validation, we selected lower-extremity radiographs of 114 normal infants with no suspicion of abuse. Readers measured the fibulas and also estimated bone ages using the knee atlas. Bone age estimates from the proposed method were compared to the other methods. The proposed method outperformed all other methods in accuracy and reproducibility. Its accuracy was similar for the testing and validating datasets, with root-mean-square error of 36 days and 37 days; mean absolute error of 28 days and 31 days; and error variability of 22 days and 20 days, respectively. This study provides strong support for an infant bone age estimation technique based on fibular shaft length as a more accurate alternative to conventional methods. (orig.)

  4. Increasing pulse wave velocity in a realistic cardiovascular model does not increase pulse pressure with age.

    Science.gov (United States)

    Mohiuddin, Mohammad W; Rihani, Ryan J; Laine, Glen A; Quick, Christopher M

    2012-07-01

    The mechanism of the well-documented increase in aortic pulse pressure (PP) with age is disputed. Investigators assuming a classical windkessel model believe that increases in PP arise from decreases in total arterial compliance (C(tot)) and increases in total peripheral resistance (R(tot)) with age. Investigators assuming a more sophisticated pulse transmission model believe PP rises because increases in pulse wave velocity (c(ph)) make the reflected pressure wave arrive earlier, augmenting systolic pressure. It has recently been shown, however, that increases in c(ph) do not have a commensurate effect on the timing of the reflected wave. We therefore used a validated, large-scale, human arterial system model that includes realistic pulse wave transmission to determine whether increases in c(ph) cause increased PP with age. First, we made the realistic arterial system model age dependent by altering cardiac output (CO), R(tot), C(tot), and c(ph) to mimic the reported changes in these parameters from age 30 to 70. Then, c(ph) was theoretically maintained constant, while C(tot), R(tot), and CO were altered. The predicted increase in PP with age was similar to the observed increase in PP. In a complementary approach, C(tot), R(tot), and CO were theoretically maintained constant, and c(ph) was increased. The predicted increase in PP was negligible. We found that increases in c(ph) have a limited effect on the timing of the reflected wave but cause the system to degenerate into a windkessel. Changes in PP can therefore be attributed to a decrease in C(tot). PMID:22561301

  5. Mouse models of telomere dysfunction phenocopy skeletal changes found in human age-related osteoporosis

    Directory of Open Access Journals (Sweden)

    Tracy A. Brennan

    2014-05-01

    Full Text Available A major medical challenge in the elderly is osteoporosis and the high risk of fracture. Telomere dysfunction is a cause of cellular senescence and telomere shortening, which occurs with age in cells from most human tissues, including bone. Telomere defects contribute to the pathogenesis of two progeroid disorders characterized by premature osteoporosis, Werner syndrome and dyskeratosis congenital. It is hypothesized that telomere shortening contributes to bone aging. We evaluated the skeletal phenotypes of mice with disrupted telomere maintenance mechanisms as models for human bone aging, including mutants in Werner helicase (Wrn−/−, telomerase (Terc−/− and Wrn−/−Terc−/− double mutants. Compared with young wild-type (WT mice, micro-computerized tomography analysis revealed that young Terc−/− and Wrn−/−Terc−/− mice have decreased trabecular bone volume, trabecular number and trabecular thickness, as well as increased trabecular spacing. In cortical bone, young Terc−/− and Wrn−/−Terc−/− mice have increased cortical thinning, and increased porosity relative to age-matched WT mice. These trabecular and cortical changes were accelerated with age in Terc−/− and Wrn−/−Terc−/− mice compared with older WT mice. Histological quantification of osteoblasts in aged mice showed a similar number of osteoblasts in all genotypes; however, significant decreases in osteoid, mineralization surface, mineral apposition rate and bone formation rate in older Terc−/− and Wrn−/−Terc−/− bone suggest that osteoblast dysfunction is a prominent feature of precocious aging in these mice. Except in the Wrn−/− single mutant, osteoclast number did not increase in any genotype. Significant alterations in mechanical parameters (structure model index, degree of anistrophy and moment of inertia of the Terc−/− and Wrn−/−Terc−/− femurs compared with WT mice were also observed. Young Wrn

  6. The "Village" Model: A Consumer-Driven Approach for Aging in Place

    Science.gov (United States)

    Scharlach, Andrew; Graham, Carrie; Lehning, Amanda

    2012-01-01

    Purpose of the Study: This study examines the characteristics of the "Village" model, an innovative consumer-driven approach that aims to promote aging in place through a combination of member supports, service referrals, and consumer engagement. Design and Methods: Thirty of 42 fully operational Villages completed 2 surveys. One survey examined…

  7. The reemergence of long-term potentiation in aged Alzheimer’s disease mouse model

    Science.gov (United States)

    Huh, Seonghoo; Baek, Soo-Ji; Lee, Kyung-Hwa; Whitcomb, Daniel J.; Jo, Jihoon; Choi, Seong-Min; Kim, Dong Hyun; Park, Man-Seok; Lee, Kun Ho; Kim, Byeong C.

    2016-01-01

    Mouse models of Alzheimer’s disease (AD) have been developed to study the pathophysiology of amyloid β protein (Aβ) toxicity, which is thought to cause severe clinical symptoms such as memory impairment in AD patients. However, inconsistencies exist between studies using these animal models, specifically in terms of the effects on synaptic plasticity, a major cellular model of learning and memory. Whereas some studies find impairments in plasticity in these models, others do not. We show that long-term potentiation (LTP), in the CA1 region of hippocampal slices from this mouse, is impared at Tg2576 adult 6–7 months old. However, LTP is inducible again in slices taken from Tg2576 aged 14–19 months old. In the aged Tg2576, we found that the percentage of parvalbumin (PV)-expressing interneurons in hippocampal CA1-3 region is significantly decreased, and LTP inhibition or reversal mediated by NRG1/ErbB signaling, which requires ErbB4 receptors in PV interneurons, is impaired. Inhibition of ErbB receptor kinase in adult Tg2576 restores LTP but impairs depotentiation as shown in aged Tg2576. Our study suggests that hippocampal LTP reemerges in aged Tg2576. However, this reemerged LTP is an insuppressible form due to impaired NRG1/ErbB signaling, possibly through the loss of PV interneurons. PMID:27377368

  8. Search for an unitary mortality law through a theoretical model for biological ageing

    CERN Document Server

    Racco, A; Penna, T J P

    1997-01-01

    In this work we check the occurrence of the Azbel assumption of mortality within the framework of a bit string model for biological ageing. We reproduced the observed feature of linear correspondence between the fitting parameters of the death rate as obtained by Azbel with demographic data.

  9. Sedimentation rates and age modeling of Late Quaternary marine sediments with unsupported 230Th

    International Nuclear Information System (INIS)

    230Th is a radionuclide of the 238U decay series, characterized by natural abundance in sediments and a half-life of 75,380 years, suitable for direct evaluation of sedimentation rates and sediment ages in a time scale of 700,000 years before the present. 230Th cycle creates a contrast between supported and unsupported 230Th in the sedimentary matrix due to the different geochemical behaviors of 230Th and its parent, 234U. This study aimed at establishing and validating a mathematical model that evaluates sedimentation rates and age modeling based on 230Th data retrieved from a sediment core sampled in the southeastern Brazilian continental margin. The validation of the age modeling of this method was made through a statistical comparison between its results and those of benthic foraminifera δ 18O record technique, widely used for sediment dating and determination of sedimentation rates. It was observed that the model of unsupported 230Th was successful in determining Late Quaternary sedimentation rates and ages in a confidence level of 95 %. It was possible to determine several breaking points in unsupported 230Th vertical profile, and it was shown that those divides correspond to some major intervals between glacial and interglacial periods when compared with the benthic foraminifera record. (author)

  10. Optimal harvesting for an age-dependent n-dimensional food chain model

    Institute of Scientific and Technical Information of China (English)

    LUO Zhi-xue; DU Ming-yin

    2008-01-01

    This paper is concerned with optimal harvesting policy for an age-dependent n-dimensional food chain model. The existence and uniqueness of non-negative solution of the system are proved using the fixed point theorem. By Mazur's theorem, the existence of optimal control strategy is demonstrated and optimality conditions derived by means of normal cone.

  11. OPTIMAL CONTROL PROBLEM FOR A PERIODIC PREDATOR-PREY MODEL WITH AGE-DEPENDENCE

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    In this paper,we investigate optimal policy for periodic predator-prey system with age-dependence.Namely,we consider the model with periodic vital rates and initial distribution.The existence of optimal control strategy is discussed by Mazur's theorem and optimality condition is derived by means of normal cone.

  12. The Source of Adult Age Differences in Event-Based Prospective Memory: A Multinomial Modeling Approach

    Science.gov (United States)

    Smith, Rebekah E.; Bayen, Ute J.

    2006-01-01

    Event-based prospective memory involves remembering to perform an action in response to a particular future event. Normal younger and older adults performed event-based prospective memory tasks in 2 experiments. The authors applied a formal multinomial processing tree model of prospective memory (Smith & Bayen, 2004) to disentangle age differences…

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

    Science.gov (United States)

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

    2012-01-01

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

  14. Positive mutations and mutation-dependent Verhulst factor in Penna ageing model

    OpenAIRE

    de Oliveira, S. Moss; Stauffer, D.; De Oliveira, P. M. C.; Martins, J. S. Sa

    2003-01-01

    We twice modify the Penna model for biological ageing. First we introduce back (good) mutations and a memory for them into the model. It allows us to observe an improvement of the species fitness over long time scales as well as punctuated equilibrium. Second we adopt a food/space competition factor that depends on the number of accumulated mutations in the individuals genomes, and get rid of the fixed limiting number of allowed mutations. Besides reproducing the main results of the standard ...

  15. Asynchronous growth and competition in a two-sex age-structured population model

    OpenAIRE

    Iannelli, Mimmo; Ripoll, Jordi

    2009-01-01

    Asynchronous exponential growth has been extensively studied in population dynamics. In this paper we find out the asymptotic behaviour in a non-linear age-dependent model which takes into account sexual reproduction interactions. The main feature of our model is that the non-linear process converges to a linear one as the solution becomes large, so that the population undergoes asynchronous growth. The steady states analysis and the corresponding stability analysis are completely made and ...

  16. On an age and spatially structured population model for Proteus Mirabilis swarm-colony development

    OpenAIRE

    Laurençot, Philippe; Walker, Christoph

    2007-01-01

    Proteus mirabilis are bacteria that make strikingly regular spatial-temporal patterns on agar surfaces. In this paper we investigate a mathematical model that has been shown to display these structures when solved numerically. The model consists of an ordinary differential equation coupled with a partial differential equation involving a first-order hyperbolic aging term together with nonlinear degenerate diffusion. The system is shown to admit global weak solutions.

  17. Traveling waves and spreading speed on a lattice model with age structure

    Directory of Open Access Journals (Sweden)

    Zongyi Wang

    2012-09-01

    Full Text Available In this article, we study a lattice differential model for a single species with distributed age-structure in an infinite patchy environment. Using method of approaches by Diekmann and Thieme, we develop a comparison principle and construct a suitable sub-solution to the given model, and show that there exists a spreading speed of the system which in fact coincides with the minimal wave speed.

  18. Classifying Human Audiometric Phenotypes of Age-Related Hearing Loss from Animal Models

    OpenAIRE

    Dubno, Judy R.; Eckert, Mark A.; Lee, Fu-Shing; Matthews, Lois J.; Schmiedt, Richard A.

    2013-01-01

    Age-related hearing loss (presbyacusis) has a complex etiology. Results from animal models detailing the effects of specific cochlear injuries on audiometric profiles may be used to understand the mechanisms underlying hearing loss in older humans and predict cochlear pathologies associated with certain audiometric configurations (“audiometric phenotypes”). Patterns of hearing loss associated with cochlear pathology in animal models were used to define schematic boundaries of human audiograms...

  19. Climatic Conditions for modelling the Northern Hemisphere ice sheets throughout the ice age cycle

    OpenAIRE

    Abe-Ouchi, A.; Segawa, T; F. Saito

    2007-01-01

    The ice sheet-climate interaction as well as the climatic response to orbital parameters and atmospheric CO2 content are examined in order to drive an ice sheet model throughout an ice age cycle. Feedback processes between ice sheet and atmosphere are analyzed by numerical experiments using a high resolution General Circulation Model (GCM) under different conditions at the Last Glacial Maximum. Among the proposed processes, the ice albedo feedback, the elevation-mass ba...

  20. Early-age behaviour of concrete in massive structures, experimentation and modelling

    International Nuclear Information System (INIS)

    This study is focused on the behaviour of concrete at early-age in massive structures, in relation with the prediction of both cracking risk and residual stresses, which is still a challenging task. In this paper, a 3D thermo-chemo-mechanical model has been developed, on the basis of complete material characterization experiments, in order to predict the early-age development of strains and residual stresses, and in order to assess the risk of cracking in massive concrete structures. The parameters of the proposed model were identified on two different concretes, High Performance Concrete and Fibrous Self-Compacted Concrete - from simple experiments in the laboratory: uniaxial tension and compression tests, dynamic Young's modulus measurements, free and autogenous shrinkages, semi-adiabatic calorimetry. The proposed model has been implemented in a Finite Element code, and the numerical simulations of the laboratory tests have proved the model consistency. Furthermore, early-age experiments conducted on massive structures have also been simulated, in order to investigate the predictive capability of the model, and to assess the model performance in practical situations where varying temperatures are involved.

  1. Early-age behaviour of concrete in massive structures, experimentation and modelling

    Energy Technology Data Exchange (ETDEWEB)

    Zreiki, J., E-mail: zreiki@lmt.ens-cachan.f [ENS Cachan/CNRS UMR8535/UPMC/PRES UniverSud Paris, Cachan (France); Bouchelaghem, F. [ENS Cachan/CNRS UMR8535/UPMC/PRES UniverSud Paris, Cachan (France); UPMC Univ Paris 06 (France); Chaouche, M. [ENS Cachan/CNRS UMR8535/UPMC/PRES UniverSud Paris, Cachan (France)

    2010-10-15

    This study is focused on the behaviour of concrete at early-age in massive structures, in relation with the prediction of both cracking risk and residual stresses, which is still a challenging task. In this paper, a 3D thermo-chemo-mechanical model has been developed, on the basis of complete material characterization experiments, in order to predict the early-age development of strains and residual stresses, and in order to assess the risk of cracking in massive concrete structures. The parameters of the proposed model were identified on two different concretes, High Performance Concrete and Fibrous Self-Compacted Concrete - from simple experiments in the laboratory: uniaxial tension and compression tests, dynamic Young's modulus measurements, free and autogenous shrinkages, semi-adiabatic calorimetry. The proposed model has been implemented in a Finite Element code, and the numerical simulations of the laboratory tests have proved the model consistency. Furthermore, early-age experiments conducted on massive structures have also been simulated, in order to investigate the predictive capability of the model, and to assess the model performance in practical situations where varying temperatures are involved.

  2. A statistical model for the study of U-Nb aging (u)

    Energy Technology Data Exchange (ETDEWEB)

    Hemphill, Geralyn M [Los Alamos National Laboratory; Hackenberg, Robert E [Los Alamos National Laboratory

    2009-01-01

    This study was undertaken to model the aging response of U-Nb alloys in order to quantify property and lifetime predictions and uncertainties, in response to concerns that aging during long-term stockpile storage may change the microstructure and properties of U-6 wt%Nb alloy components in ways adversely affecting performance. U-6Nb has many desirable properties, but is a complex material because of its gross compositional inhomogeneity (its chemical banding spans 4-8 wt%), its metastable starting microstructure, and the fact that a variety of external factors such as temperature, stress, and gaseous species can cause aging through multiple mechanisms. The most significant aging mechanism identified in earlier studies [2007hac2] is age hardening, phenomenologically defined as increasing hardness and strength and decreasing ductility observed as a function of increasing aging time-at-temperature. The scientific fundamentals of age hardening at temperatures relevant to U-6Nb material processing ({le}200 C) and stockpile storage ({le}60 C) remain unresolved in spite of significant experimental efforts [2007hac2, 2009cla]. Equally problematic is the lack of a well-established U-6Nb component failure criterion. These limitations make the most desirable approach of property response and lifetime prediction - that based on fundamental physics - unattainable at the present time. Therefore, a semi-empirical approach was taken to model the phenomenological property evolution during aging. This enabled lifetime estimates to be made from an assumed failure criterion (derived from a manufacturing acceptance criterion) couched in terms of an age-sensitive property, namely quasi-static tensile elongation to failure. The predictions of this and other age-sensitive properties are also useful for U-6Nb component surveillance studies. Drawing upon a large body of artificial aging data obtained from nonbanded (chemically homogeneous) U-5.6Nb and U-7.7Nb material [2007hacJ ] over 100

  3. Modelling of Dynamic Strain Aging with a Dislocation-Based Isotropic Hardening Model and Investigation of Orthogonal Loading

    NARCIS (Netherlands)

    Berisha, B.; Hora, P.; Tong, L.; Wahlen, A.; Boogaard, van den A.H.

    2008-01-01

    Based on experimental results, a dislocation material model describing the dynamic strain aging effect at different temperatures is presented. One and two stage loading tests were performed in order to investigate the influence of the loading direction as well as the temperature influence due to the

  4. Quality Saving Mechanisms of Mitochondria during Aging in a Fully Time-Dependent Computational Biophysical Model.

    Science.gov (United States)

    Mellem, Daniel; Fischer, Frank; Jaspers, Sören; Wenck, Horst; Rübhausen, Michael

    2016-01-01

    Mitochondria are essential for the energy production of eukaryotic cells. During aging mitochondria run through various processes which change their quality in terms of activity, health and metabolic supply. In recent years, many of these processes such as fission and fusion of mitochondria, mitophagy, mitochondrial biogenesis and energy consumption have been subject of research. Based on numerous experimental insights, it was possible to qualify mitochondrial behaviour in computational simulations. Here, we present a new biophysical model based on the approach of Figge et al. in 2012. We introduce exponential decay and growth laws for each mitochondrial process to derive its time-dependent probability during the aging of cells. All mitochondrial processes of the original model are mathematically and biophysically redefined and additional processes are implemented: Mitochondrial fission and fusion is separated into a metabolic outer-membrane part and a protein-related inner-membrane part, a quality-dependent threshold for mitophagy and mitochondrial biogenesis is introduced and processes for activity-dependent internal oxidative stress as well as mitochondrial repair mechanisms are newly included. Our findings reveal a decrease of mitochondrial quality and a fragmentation of the mitochondrial network during aging. Additionally, the model discloses a quality increasing mechanism due to the interplay of the mitophagy and biogenesis cycle and the fission and fusion cycle of mitochondria. It is revealed that decreased mitochondrial repair can be a quality saving process in aged cells. Furthermore, the model finds strategies to sustain the quality of the mitochondrial network in cells with high production rates of reactive oxygen species due to large energy demands. Hence, the model adds new insights to biophysical mechanisms of mitochondrial aging and provides novel understandings of the interdependency of mitochondrial processes. PMID:26771181

  5. Quality Saving Mechanisms of Mitochondria during Aging in a Fully Time-Dependent Computational Biophysical Model.

    Directory of Open Access Journals (Sweden)

    Daniel Mellem

    Full Text Available Mitochondria are essential for the energy production of eukaryotic cells. During aging mitochondria run through various processes which change their quality in terms of activity, health and metabolic supply. In recent years, many of these processes such as fission and fusion of mitochondria, mitophagy, mitochondrial biogenesis and energy consumption have been subject of research. Based on numerous experimental insights, it was possible to qualify mitochondrial behaviour in computational simulations. Here, we present a new biophysical model based on the approach of Figge et al. in 2012. We introduce exponential decay and growth laws for each mitochondrial process to derive its time-dependent probability during the aging of cells. All mitochondrial processes of the original model are mathematically and biophysically redefined and additional processes are implemented: Mitochondrial fission and fusion is separated into a metabolic outer-membrane part and a protein-related inner-membrane part, a quality-dependent threshold for mitophagy and mitochondrial biogenesis is introduced and processes for activity-dependent internal oxidative stress as well as mitochondrial repair mechanisms are newly included. Our findings reveal a decrease of mitochondrial quality and a fragmentation of the mitochondrial network during aging. Additionally, the model discloses a quality increasing mechanism due to the interplay of the mitophagy and biogenesis cycle and the fission and fusion cycle of mitochondria. It is revealed that decreased mitochondrial repair can be a quality saving process in aged cells. Furthermore, the model finds strategies to sustain the quality of the mitochondrial network in cells with high production rates of reactive oxygen species due to large energy demands. Hence, the model adds new insights to biophysical mechanisms of mitochondrial aging and provides novel understandings of the interdependency of mitochondrial processes.

  6. Mechanisms of skeletal muscle aging: insights from Drosophila and mammalian models

    Directory of Open Access Journals (Sweden)

    Fabio Demontis

    2013-11-01

    Full Text Available A characteristic feature of aged humans and other mammals is the debilitating, progressive loss of skeletal muscle function and mass that is known as sarcopenia. Age-related muscle dysfunction occurs to an even greater extent during the relatively short lifespan of the fruit fly Drosophila melanogaster. Studies in model organisms indicate that sarcopenia is driven by a combination of muscle tissue extrinsic and intrinsic factors, and that it fundamentally differs from the rapid atrophy of muscles observed following disuse and fasting. Extrinsic changes in innervation, stem cell function and endocrine regulation of muscle homeostasis contribute to muscle aging. In addition, organelle dysfunction and compromised protein homeostasis are among the primary intrinsic causes. Some of these age-related changes can in turn contribute to the induction of compensatory stress responses that have a protective role during muscle aging. In this Review, we outline how studies in Drosophila and mammalian model organisms can each provide distinct advantages to facilitate the understanding of this complex multifactorial condition and how they can be used to identify suitable therapies.

  7. Age- and sex-dependent model for estimating radioiodine dose to a normal thyroid

    International Nuclear Information System (INIS)

    This paper describes the derivation of an age- and sex-dependent model of radioiodine dosimetry in the thyroid and the application of the model to estimating the thyroid dose for each of 4215 patients who were exposed to 131I in diagnostic and therapeutic procedures. The model was made to conform to these data requirements by the use of age-specific estimates of the biological half-time of iodine in the thyroid and an age- and sex-dependent representation of the mass of the thyroid. Also, it was assumed that the thyroid burden was maximum 24 hours after administration (the 131I dose is not critically sensitive to this assumption). The metabolic model is of the form A(t) = K[exp(-μ1t) - exp(-μ2t)] (μCi), where μ1 = lambda/sub r/ + lambda/sub i//sup b/ (i = 1, 2), lambda/sub r/ is the radiological decay-rate coefficient, and lambda/sub i//sup b/ are biological removal rate coefficients. The values of lambda/sub i//sup b/ are determined by solving a nonlinear equation that depends on assumptions about the time of maximum uptake and the eventual biological loss rate (through which age dependence enters). The value of K may then be calculated from knowledge of the uptake at a particular time. The dosimetric S-factor (rad/μCi-day) is based on specific absorbed fractions for photons of energy ranging from 0.01 to 4.0 MeV for thyroid masses from 1.29 to 19.6 g; the functional form of the S-factor also involves the thyroid mass explicitly, through which the dependence on age and sex enters. An analysis of sensitivity of the model to uncertainties in the thyroid mass and the biological removal rate for several age groups is reported. The model could prove useful in the dosimetry of very short-lived radioiodines. Tables of age- and sex-dependent coefficients are provided to enable readers to make their own calculations. 12 refs., 5 figs., 4 tabs

  8. Modelling of the aging behavior of polyamide 12 powder during laser melting process

    Science.gov (United States)

    Drummer, Dietmar; Wudy, Katrin; Drexler, Maximilian

    2015-05-01

    Concerning individualization, the requirements to products have increased. Additive manufacturing technologies, such as selective laser melting allow manufacturing of complex parts without tools and forms. Due to this additive manufacturing processes comply, in opposite to conventional techniques, with these increased demands on processing technology. Due to the high temperature during processing, a degradation of the used plastic powder occurs. The non-molten material in the building chamber, the so-called partcake, can be removed after building from the finished component and reused for another process. To realize reproducible part properties refreshing of partcake powder with 30 up to 50 % virgin powder is necessary. However, these refreshing strategies lead to varying component properties due to an undefined aging state. Previous investigations on oven aged powder for selective laser melting showed for short periods of storage near the melting point thermally induced post condensation is the predominate aging effect. Due to post condensation the molecular weight and thus the viscosity increases. This paper focuses on the modeling of the post condensation process to define the aging state of polyamide 12 powder in laser melting process. Therefore the rheological behavior of PA 12 powder in dependency of time and temperature is investigated. Isothermal viscosity measurements are conducted in order to describe the post condensation reaction with a model. With knowledge of the kinetics of the post condensation reaction the state of aging can be predicted in a second step. Thus expected useful life of the powder can be calculated in dependency of the building chamber temperature. These results are then compared with viscosity values of defined aged PA 12 powder to validate the determined model.

  9. On four-phase model of iron-beryllium alloy structure on initial stages of aging

    International Nuclear Information System (INIS)

    The structural changes in Fe-Be alloys (from 16.5 and 19.5 % Be) were studied on various stages of aging in the range of temperatures from 300 to 500 deg C by microdiffraction in an electron microscope and by diffusion scattering of X-rays by microcrystals. Regularities were established of the formation of a four-phase model (two cubic and two tetragonal phases, coherently associated at earlier stages of aging). The four-phase structure is formed in the process of a regular arrangement of particles along the directions

  10. Fitting model of ABR age dependency in a clinical population of normal hearing children

    OpenAIRE

    Coenraad, Saskia; Immerzeel, Tabitha; Hoeve, Hans; Goedegebure, Andre

    2010-01-01

    textabstractThe purpose of this study was to present a simple and powerful fitting model that describes age-dependent changes of auditory brainstem responses (ABR) in a clinical population of normal hearing children. A total of 175 children (younger than 200 weeks postconceptional age) were referred for audiologic assessment with normal ABR results. ABR parameters of normal hearing children between 2003 and 2008 were included. The results of the right ears recorded at 90 dB nHL were analyzed....

  11. Asteroid age distributions determined by space weathering and collisional evolution models

    OpenAIRE

    Willman, Mark; Jedicke, Robert

    2010-01-01

    We provide evidence of consistency between the dynamical evolution of main belt asteroids and their color evolution due to space weathering. The dynamical age of an asteroid's surface \\citep{bib.bot05a,bib.nes05} is the time since its last catastrophic disruption event which is a function of the object's diameter. The age of an S-complex asteroid's surface may also be determined from its color using a space weathering model \\citep[e.g.][]{bib.wil10,bib.jed04,bib.wil08,bib.mar06}. We used a sa...

  12. Capacitance recovery analysis and modelling of supercapacitors during cycling ageing tests

    International Nuclear Information System (INIS)

    Highlights: • The performances degradation of supercapacitors during power cycling ageing tests have been quantified. • The performances recovery phenomena of supercapacitors is highlighted and modelled. • The impact of the rest conditions (temperature and cut-off voltage) on the recovery behaviour is quantified. • An accurate ageing model able to predict the performances degradation of supercapacitors in power cycling is proposed. - Abstract: During accelerated ageing tests of supercapacitors (SC), a decay in their performance is reflected by a decrease in capacitance and an increase in equivalent series resistance ESR. In power cycling, when electric solicitations of the SC are interrupted for the purposes of real use or characterisation, performance recovery is observed, mainly in terms of an increase in capacitance. This phenomenon is due to a redistribution of electrical charges, balancing of impurities inside the porous carbon electrodes, and the cell’s return to thermodynamically steady-state conditions. A repetitive long rest period during cycling appears to slow down the ageing process, and to reduce the decay in performance. The impacts on capacitance recovery during rest time, of both cut-off voltage and temperature, are studied. A nonlinear analytical expression is used to predict the capacitance decay for several durations and test interruption periodicities; this is also used to model the capacitance during rest time, taking the cut-off voltage, rest time and temperature into account

  13. Ageing, menopause, and ischaemic heart disease mortality in England, Wales, and the United States: modelling study of national mortality data

    OpenAIRE

    Vaidya, Dhananjay; Becker, Diane M.; Bittner, Vera; Mathias, Rasika A.; Ouyang, Pamela

    2011-01-01

    Objectives To use changes in heart disease mortality rates with age to investigate the plausibility of attributing women’s lower heart disease mortality than men to the protective effects of premenopausal sex hormones. Design Modelling study of longitudinal mortality data with models assuming (i) a linear association between mortality rates and age (absolute mortality) or (ii) a logarithmic association (proportional mortality). We fitted models to age and sex specific mortality rates in the c...

  14. Epigenetic contribution to age distribution of mortality within the Penna model.

    Science.gov (United States)

    Magdoń-Maksymowicz, M S; Maksymowicz, A Z

    2015-06-01

    Some modifications of the simple asexual Penna model, enriched by epigenetic contributions, are presented. The standard bit-string Penna model of biological aging and population evolution is based on an inherited DNA structure which defines the future life of a newly born individuals, when genes are activated by the biological clock, and the predefined genetic death is fully controlled by the number of defected genes. Epigenomes allow to introduce additional mechanism of gene activation or silencing without affecting the DNA genome itself. It may be either inherited or may reflect external, environmental factors. In the presented model, information read from the introduced epigenome may alter gene expression that may be stopped or re-activated. We concentrate on the influence of epigenetics on the age a distribution of genetic mortality m(a). Changes in m(a) are strong for the case of inherited epigenetic contribution with nearly perfect inheritance and 'positive' epigenome that partly ignores the 'bad' mutations. We conclude that the epigenetic contribution may influence population structure m(a) and could be, at least partly, responsible for deviation of m(a) distribution from the Gompertz law. In short, we claim that proposed epigenetic contribution may be seen as a candidate for possible explanation of observed deviation from the Gompertz law, also among senior members of society. A very simple model was used in this paper and many crucial mechanisms of biological aging were omitted. Therefore, further work based on a more realistic models is necessary. PMID:25666268

  15. Clarifying hierarchical age-period-cohort models: A rejoinder to Bell and Jones.

    Science.gov (United States)

    Reither, Eric N; Land, Kenneth C; Jeon, Sun Y; Powers, Daniel A; Masters, Ryan K; Zheng, Hui; Hardy, Melissa A; Keyes, Katherine M; Fu, Qiang; Hanson, Heidi A; Smith, Ken R; Utz, Rebecca L; Yang, Y Claire

    2015-11-01

    Previously, Reither et al. (2015) demonstrated that hierarchical age-period-cohort (HAPC) models perform well when basic assumptions are satisfied. To contest this finding, Bell and Jones (2015) invent a data generating process (DGP) that borrows age, period and cohort effects from different equations in Reither et al. (2015). When HAPC models applied to data simulated from this DGP fail to recover the patterning of APC effects, B&J reiterate their view that these models provide "misleading evidence dressed up as science." Despite such strong words, B&J show no curiosity about their own simulated data--and therefore once again misapply HAPC models to data that violate important assumptions. In this response, we illustrate how a careful analyst could have used simple descriptive plots and model selection statistics to verify that (a) period effects are not present in these data, and (b) age and cohort effects are conflated. By accounting for the characteristics of B&J's artificial data structure, we successfully recover the "true" DGP through an appropriately specified model. We conclude that B&Js main contribution to science is to remind analysts that APC models will fail in the presence of exact algebraic effects (i.e., effects with no random/stochastic components), and when collinear temporal dimensions are included without taking special care in the modeling process. The expanded list of coauthors on this commentary represents an emerging consensus among APC scholars that B&J's essential strategy--testing HAPC models with data simulated from contrived DGPs that violate important assumptions--is not a productive way to advance the discussion about innovative APC methods in epidemiology and the social sciences. PMID:26277370

  16. Age- and sex-dependent model for estimating radioiodine dose to a normal thyroid

    International Nuclear Information System (INIS)

    This paper describes the derivation of an age- and sex-dependent model of radioiodine dosimetry in the thyroid and the application of the model to estimating the thyroid dose for each of 4215 patients who were exposed to 131I in diagnostic and therapeutic procedures. In most cases, the available data consisted of the patient's age at the time of administration, the patient's sex, the quantity of activity administered, the clinically-determined uptake of radioiodine by the thyroid, and the time after administration at which the uptake was determined. The metabolic model is of the form A(t) = K[exp(-μ1t) -exp(-μ2t)] (μCi), where μ1 = λ/sub r/ - λ/sub i//sup b/ (i = 1, 2), λ/sub r/ is the radiological decay-rate coefficient, and λ/sub i//sup b/ are biological removal rate coefficients. The values of λ/sub i//sup b/ are determined by solving a nonlinear equation that depends on assumptions about the time or maximum uptake an the eventual biological loss rate (through which age dependence enters). The value of K may then be calculated from knowledge of the uptakes at a particular time. The dosimetric S-factor (rad/μCi-day) is based on specific absorbed fractions for photons of energy ranging from 0.01 to 4.0 MeV for thyroid masses from 1.29 to 19.6 g; the functional form of the S-factor also involves the thyroid mass explicitly, through which the dependence on age and sex enters. An analysis of sensitivity of the model to uncertainties in the thyroid mass and the biological removal rate for several age groups is reported. 12 references, 5 figures, 5 tables

  17. Modeling basic creep in concrete at early-age under compressive and tensile loading

    Energy Technology Data Exchange (ETDEWEB)

    Hilaire, Adrien, E-mail: adrien.hilaire@ens-cachan.fr [ENS Cachan/CNRS UMR8535/UPMC/PRES UniverSud Paris, Cachan (France); Benboudjema, Farid; Darquennes, Aveline; Berthaud, Yves [ENS Cachan/CNRS UMR8535/UPMC/PRES UniverSud Paris, Cachan (France); Nahas, Georges [ENS Cachan/CNRS UMR8535/UPMC/PRES UniverSud Paris, Cachan (France); Institut de radioprotection et de sureté nucléaire, Fontenay-aux-Roses (France)

    2014-04-01

    A numerical model has been developed to predict early age cracking for massive concrete structures, and especially concrete nuclear containment vessels. Major phenomena are included: hydration, heat diffusion, autogenous and thermal shrinkage, creep and cracking. Since studied structures are massive, drying is not taken into account. Such modeling requires the identification of several material parameters. Literature data is used to validate the basic creep model. A massive wall, representative of a concrete nuclear containment, is simulated; predicted cracking is consistent with observation and is found highly sensitive to the creep phenomenon.

  18. Modeling basic creep in concrete at early-age under compressive and tensile loading

    International Nuclear Information System (INIS)

    A numerical model has been developed to predict early age cracking for massive concrete structures, and especially concrete nuclear containment vessels. Major phenomena are included: hydration, heat diffusion, autogenous and thermal shrinkage, creep and cracking. Since studied structures are massive, drying is not taken into account. Such modeling requires the identification of several material parameters. Literature data is used to validate the basic creep model. A massive wall, representative of a concrete nuclear containment, is simulated; predicted cracking is consistent with observation and is found highly sensitive to the creep phenomenon

  19. Estimating Modifying Effect of Age on Genetic and Environmental Variance Components in Twin Models.

    Science.gov (United States)

    He, Liang; Sillanpää, Mikko J; Silventoinen, Karri; Kaprio, Jaakko; Pitkäniemi, Janne

    2016-04-01

    Twin studies have been adopted for decades to disentangle the relative genetic and environmental contributions for a wide range of traits. However, heritability estimation based on the classical twin models does not take into account dynamic behavior of the variance components over age. Varying variance of the genetic component over age can imply the existence of gene-environment (G×E) interactions that general genome-wide association studies (GWAS) fail to capture, which may lead to the inconsistency of heritability estimates between twin design and GWAS. Existing parametricG×Einteraction models for twin studies are limited by assuming a linear or quadratic form of the variance curves with respect to a moderator that can, however, be overly restricted in reality. Here we propose spline-based approaches to explore the variance curves of the genetic and environmental components. We choose the additive genetic, common, and unique environmental variance components (ACE) model as the starting point. We treat the component variances as variance functions with respect to age modeled by B-splines or P-splines. We develop an empirical Bayes method to estimate the variance curves together with their confidence bands and provide an R package for public use. Our simulations demonstrate that the proposed methods accurately capture dynamic behavior of the component variances in terms of mean square errors with a data set of >10,000 twin pairs. Using the proposed methods as an alternative and major extension to the classical twin models, our analyses with a large-scale Finnish twin data set (19,510 MZ twins and 27,312 DZ same-sex twins) discover that the variances of the A, C, and E components for body mass index (BMI) change substantially across life span in different patterns and the heritability of BMI drops to ∼50% after middle age. The results further indicate that the decline of heritability is due to increasing unique environmental variance, which provides more

  20. Influence of Age on Ocular Biomechanical Properties in a Canine Glaucoma Model with ADAMTS10 Mutation

    Science.gov (United States)

    Palko, Joel R.; Morris, Hugh J.; Pan, Xueliang; Harman, Christine D.; Koehl, Kristin L.; Gelatt, Kirk N.; Plummer, Caryn E.; Komáromy, András M.; Liu, Jun

    2016-01-01

    Soft tissue often displays marked age-associated stiffening. This study aims to investigate how age affects scleral biomechanical properties in a canine glaucoma model with ADAMTS10 mutation, whose extracellular matrix is concomitantly influenced by the mutation and an increased mechanical load from an early age. Biomechanical data was acquired from ADAMTS10-mutant dogs (n = 10, 21 to 131 months) and normal dogs (n = 5, 69 to 113 months). Infusion testing was first performed in the whole globes to measure ocular rigidity. After infusion experiments, the corneas were immediately trephined to prepare scleral shells that were mounted on a pressurization chamber to measure strains in the posterior sclera using an inflation testing protocol. Dynamic viscoelastic mechanical testing was then performed on dissected posterior scleral strips and the data were combined with those reported earlier by our group from the same animal model (Palko et al, IOVS 2013). The association between age and scleral biomechanical properties was evaluated using multivariate linear regression. The relationships between scleral properties and the mean and last measured intraocular pressure (IOP) were also evaluated. Our results showed that age was positively associated with complex modulus (page. The regression slopes were not different between the groups, although the complex modulus was significantly lower in the affected group (p = 0.041). The posterior circumferential tangential strain was negatively correlated with complex modulus (R = -0.744, p = 0.006) showing consistent mechanical evaluation between the testing methods. Normalized ocular rigidity was negatively correlated with the last IOP in the affected group (p = 0.003). Despite a mutation that affects the extracellular matrix and a chronic IOP elevation in the affected dogs, age-associated scleral stiffening and loss of mechanical damping were still prominent and had a similar rate of change as in the normal dogs. PMID:27271467

  1. AGE CLASSIFICATIONS BASED ON SECOND ORDER IMAGE COMPRESSED AND FUZZY REDUCED GREY LEVEL (SICFRG MODEL

    Directory of Open Access Journals (Sweden)

    Jangala. Sasi Kiran

    2013-06-01

    Full Text Available One of the most fundamental issues in image classification and recognition are how to characterize images using derived features. Many texture classification and recognition problems in the literature usually require the computation on entire image set and with large range of gray level values in order to achieve efficient and precise classification and recognition. This leads to lot of complexity in evaluating feature parameters. To address this,the present paper derives a Second Order image Compressed and Fuzzy Reduced Grey level (SICFRG model, which reduces the image dimension and grey level range without any loss of significant feature information. The present paper derives GLCM features on the proposed SICFRG model for efficient age classification that classifies facial image into a five groups. The SICFRG image mode of age classification is derived in three stages. In the first stage the 5 x 5 matrix is compressed into a 2 x 2 second order sub matrix without loosing anysignificant attributes, primitives, and any other local properties. In stage 2 Fuzzy logic is applied tPo reduce the Gray level range of compressed model of the image. In stage 3 GLCM is derived on SICFRG model of the image. The experimental evidence on FG-NET and Google aging database clearly indicates the high classification rate of the proposed method over the other methods.

  2. Effect of aging on airway remodeling and muscarinic receptors in a murine acute asthma model

    Directory of Open Access Journals (Sweden)

    Kang JY

    2013-10-01

    Full Text Available Ji Young Kang, Sook Young Lee, Chin Kook Rhee, Seung Joon Kim, Soon Seog Kwon, Young Kyoon KimDepartment of Internal Medicine, College of Medicine, Catholic University of Korea, Seoul, KoreaBackground and objectives: The influence of aging on the development of asthma has not been studied thoroughly. The aim of this study was to investigate age-related airway responses involving lung histology and expression of muscarinic receptors in a murine model of acute asthma. Methods: Female BALB/c mice at the ages of 6 weeks and 6, 9, and 12 months were sensitized and challenged with ovalbumin (OVA for 1 month (n = 8–12 per group. We analyzed inflammatory cells and T-helper (Th2 cytokines in bronchoalveolar lavage (BAL fluid and parameters of airway remodeling and expression of muscarinic receptors in lung tissue. Results: Among the OVA groups, total cell and eosinophil numbers in BAL fluid were significantly higher in the older (6-, 9-, and 12-month-old mice than in the young (6-week-old mice. Interleukin (IL 4 (IL-4 concentration increased, but IL-5 and IL-13 concentrations showed a decreased tendency, with age. IL-17 concentration tended to increase with age, which did not reach statistical significance. periodic acid-Schiff (PAS staining area, peribronchial collagen deposition, and area of α-smooth muscle staining were significantly higher in the 6-month older OVA group than in the young OVA group. The expression of the M3 and M2 muscarinic receptors tended to increase and decrease, respectively, with age. Conclusion: The aged mice showed an active and unique pattern not only on airway inflammation, but also on airway remodeling and expression of the muscarinic receptors during the development of acute asthma compared with the young mice. These findings suggest that the aging process affects the pathogenesis of acute asthma and age-specific approach might be more appropriate for better asthma control in a clinical practice.Keywords: aging, asthma

  3. Touchscreen-based cognitive tasks reveal age-related impairment in a primate aging model, the grey mouse lemur (Microcebus murinus.

    Directory of Open Access Journals (Sweden)

    Marine Joly

    Full Text Available Mouse lemurs are suggested to represent promising novel non-human primate models for aging research. However, standardized and cross-taxa cognitive testing methods are still lacking. Touchscreen-based testing procedures have proven high stimulus control and reliability in humans and rodents. The aim of this study was to adapt these procedures to mouse lemurs, thereby exploring the effect of age. We measured appetitive learning and cognitive flexibility of two age groups by applying pairwise visual discrimination (PD and reversal learning (PDR tasks. On average, mouse lemurs needed 24 days of training before starting with the PD task. Individual performances in PD and PDR tasks correlate significantly, suggesting that individual learning performance is unrelated to the respective task. Compared to the young, aged mouse lemurs showed impairments in both PD and PDR tasks. They needed significantly more trials to reach the task criteria. A much higher inter-individual variation in old than in young adults was revealed. Furthermore, in the PDR task, we found a significantly higher perseverance in aged compared to young adults, indicating an age-related deficit in cognitive flexibility. This study presents the first touchscreen-based data on the cognitive skills and age-related dysfunction in mouse lemurs and provides a unique basis to study mechanisms of inter-individual variation. It furthermore opens exciting perspectives for comparative approaches in aging, personality, and evolutionary research.

  4. A dynamic model of the marriage market. Part 1 : Matching algorithm based on age preference and availability

    OpenAIRE

    Matthews, A P; Garenne, Michel

    2013-01-01

    The matching algorithm in a dynamic marriage market model is described in this first of two companion papers. Iterative Proportional Fitting is used to find a marriage function (an age distribution of new marriages for both sexes), in a stable reference population, that is consistent with the one-sex age distributions of new marriages, and includes age preference. The one-sex age distributions (which are the marginals of the two-sex distribution) are based on the Picrate model, and age prefer...

  5. Mitochondrial dysfunction in the striatum of aged chronic mouse model of Parkinson's disease

    Directory of Open Access Journals (Sweden)

    Gaurav Patki

    2009-12-01

    Full Text Available Mitochondrial oxidative stress and dysfunction has been implicated as a possible mechanism for the onset and progression of Parkinson-like neurodegeneration. However, long-term mitochondrial defects in chronic animal neurodegenerative models have not been demonstrated. In this study, we investigated the function of striatal mitochondria 6 weeks after the induction of a chronic 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP mouse model of Parkinson’s disease (MPD. Although severe depression of mitochondrial respiration was observed immediately after acute administrations of MPTP, we failed to detect a significant mitochondrial inhibition in presence of striatal dopamine deficit 6 weeks after the chronic MPD induction in young adult mice. In contrast, when aged mice were chronically treated with MPTP and at 6 weeks post-treatment, these animals suffered an inhibition of the basal (state 4 and ADP-stimulated (state 3 respiration and a fall in ATP level in the striatal mitochondria. The aged chronic MPD also brought about a sustained diminution of striatal anti-oxidant enzyme levels including that of superoxide dismutases and cytochrome c. The mitochondrial deficits in the striatum of aged chronic MPD 6 weeks after treatment were further correlated with significant losses of striatal dopamine, tyrosine hydroxylase, dopamine uptake transporter, and with impaired movement when tested on a challenging beam. Our findings suggest that MPTP may trigger the neurodegenerative process by obstructing the mitochondrial function; however, striatal mitochondria in young animals may potentially rejuvenate, whereas mitochondrial dysfunction is sustained in the aged chronic MPD. Therefore, the aged chronic MPD may serve as a suitable investigative model for further elucidating the integral relationship between mitochondrial dysfunction and neurodegenerative disorder, and for assessing the therapeutic efficacy of mitochondrial protective agents as potential

  6. Age model of fertility in Vojvodina at the beginning of the 21st century

    Directory of Open Access Journals (Sweden)

    Veljović Radmila

    2014-01-01

    Full Text Available This paper presents an outlook on fertility trends of the population of Vojvodina in the first decade of the 21st century, a period that includes the results of the previous two Censuses held in 2002 and 2011. The main concern is identifying determinants of this development process and the dynamics regarding the age model of fertility as well as the way it is manifested in Vojvodina. Methodology of this research relies on evaluating age specific rates, determining its fluctuations and shifts in order to establish the course of the change. Census of 2002 and Census of 2011 provide useful data to complete fertility analyses. Total fertility rates also show the tendency of continuous decline therefore representing the shifts in the age model of fertility. After the devastating 1990s marked by wars and sanctions, the transitional processes were initiated at the turn of the millennium, leading to a change in socio-economic environment. Along with constant economic crisis and accompanying poverty, this situation strongly influenced reproductive behaviour of women and their attitude toward childbearing in general. The trend of late childbearing and a raise of women’s mean age at first birth continued.

  7. Reliability of some ageing nuclear power plant systems: a simple stochastic model

    International Nuclear Information System (INIS)

    The random number of failure-related events in certain repairable ageing systems, like certain nuclear power plant components, during a given time interval, may be often modelled by a compound Poisson distribution. One of these is the Polya-Aeppli distribution. The derivation of a stationary Polya-Aeppli distribution as a limiting distribution of rare events for stationary Bernouilli trials with first order Markov dependence is considered. But if the parameters of the Polya-Aeppli distribution are suitable time functions, we could expect that the resulting distribution would allow us to take into account the distribution of failure-related events in an ageing system. Assuming that a critical number of damages produce an emergent failure, the abovementioned results can be applied in a reliability analysis. It is natural to ask under what conditions a Polya-Aeppli distribution could be a limiting distribution for non-homogeneous Bernouilli trials with first order Markov dependence. In this paper this problem is analyzed and possible applications of the obtained results to ageing or deteriorating nuclear power plant components are considered. The two traditional ways of modelling repairable systems in reliability theory: the - as bad as old - concept, that assumes that the replaced component is exactly under the same conditions as was the aged component before failure, and the - as good as new - concept, that assumes that the new component is under the same conditions of the replaced component when it was new, are briefly discussed in relation with the findings of the present work

  8. Transforming Growth Factor-β1 Fails to Stimulate Wound Healing and Impairs Its Signal Transduction in an Aged Ischemic Ulcer Model : Importance of Oxygen and Age

    OpenAIRE

    Wu, Liancun; Xia, Yu-Ping; Roth, Sanford I.; Gruskin, Elliott; Mustoe, Thomas A.

    1999-01-01

    Clinical trials of exogenous growth factors in treating chronic wounds have been less successful than expected. One possible explanation is that most studies used animal models of acute wounds in young animals, whereas most chronic wounds occur in elderly patients with tissue ischemia. We described an animal model of age- and ischemia-impaired wound healing and analyzed the wound-healing response as well as the transforming growth factor (TGF)-β1 effect in this model. Rabbits of increasing ag...

  9. Influence of age and sex on pharmacodynamics of propofol in neurosurgical patients: model development

    Institute of Scientific and Technical Information of China (English)

    Yu-hong LI; Fu-sheng WU; Jian-guo XU

    2006-01-01

    Aim: To determine propofol concentration in the cerebral spinal fluid (CSF) of neurosurgical patients and carry out a preliminary population pharmacodynamic study. Methods: Twenty-seven elective neurosurgical patients (12 men and 15 women) aged 17-74 years received propofol in a bolus dose of 2 mg/kg for 5 min and an infusion of 10 mg/kg per h for 5 min. Frequent CSF samples were drawn and assayed for propofol concentration. The bispectral index (BIS) was used to measure the drug effect. All data were analyzed first with the Excel software package, then pharmacodynamics modeling was performed using the NONMEM software package. Results: The CSF concentration was related to the drug effect with linear and sigmoid Emax models. The parameters for the linear addictive model were a= 1.11 and b=95.4. The parameters for the linear exponential model were a= 1.05 and b=92.7. The parameters for the sigmoid Emax model were Emax=119, EC50= 53.6 ng/Ml, and W=1.51. When the covariates of age, weight and sex were considered, the parameters of models, objective function, the standard error of the mean and the prediction error were not optimized. Conclusion: Linear additive, linear exponential and sigmoid Emax models can be used to describe the pharmacodynamics of propofol with respect to the concentration in CSF. In this small population, age (17-74 years), weight (47-98 kg) and sex did not influence any of the pharmacodynamic parameters of propofol. To verify these preliminary results, a larger study population is required.

  10. Calibration of a ground water contamination transport model using Tritium-3Helium ages

    International Nuclear Information System (INIS)

    Full text: Dow Terneuzen is the largest US chemical industrial site in Europe. Situated in the southern part of The Netherlands at the southern shore of the Westershelde, the site occupies an area of roughly 2km times 3km. Several contaminant plumes are known in the ground water below the industrial area. They originate from accidents in the fifties until seventies and are transported with the ground water flow towards the borders of the site. Detailed hydrogeological investigations lead to a three-dimensional numerical model of ground water flow and transport. Although this model was carefully calibrated using the hydraulic heads, unrealistic travel times and ground water ages were obtained. In a case study one of the contaminant plumes was investigated for ground water age and distance velocity. Out of three multilevel wells along the plume a total of 13 samples for T/3He were obtained. All samples contained tritium, indicating a component of ground water younger than 40 years, whereas the numerical model gave travel times between 40 and 160 years. The Tritium data are further confirmed by SF6 which was present in concentrations well above the present day atmospheric equilibrium in two out of three samples. Two facts hamper the interpretation of the noble gas data as T/3He ages: i) Degradation of the organic contaminant (benzene) results in CO2 and CH4 production causing loss of noble gases in the aquifer by a stripping process. This also caused problems during the sampling and made the interpretation of the data as ages impossible for 5 of the 13 samples. ii) Ground water infiltration temperatures are unknown but elevated due to process heat released from the industrial environment. Accuracy of the derived ages is limited mainly by this unknown infiltration temperature. Despite these difficulties the derived T/ 3 He ages give clear hints for the improvement of the numerical model. Most probably ground water infiltration does not take place on the whole area as

  11. Calibration of a ground water contamination transport model using Tritium-3Helium ages

    International Nuclear Information System (INIS)

    Full text: Dow Terneuzen is the largest US chemical industrial site in Europe. Situated in the southern part of The Netherlands at the southern shore of the Westershelde, the site occupies an area of roughly 2km times 3km. Several contaminant plumes are known in the ground water below the industrial area. They originate from accidents in the fifties until seventies and are transported with the ground water flow towards the borders of the site. Detailed hydrogeological investigations lead to a three-dimensional numerical model of ground water flow and transport. Although this model was carefully calibrated using the hydraulic heads, unrealistic travel times and ground water ages were obtained. In a case study one of the contaminant plumes was investigated for ground water age and distance velocity. Out of three multilevel wells along the plume a total of 13 samples for T/3He were obtained. All samples contained tritium, indicating a component of ground water younger than 40 years, whereas the numerical model gave travel times between 40 and 160 years. The Tritium data are further confirmed by SF6 which was present in concentrations well above the present day atmospheric equilibrium in two out of three samples. Two facts hamper the interpretation of the noble gas data as T/3He ages: i) Degradation of the organic contaminant (benzene) results in CO2 and CH4 production causing loss of noble gases in the aquifer by a stripping process. This also caused problems during the sampling and made the interpretation of the data as ages impossible for 5 of the 13 samples. ii) Ground water infiltration temperatures are unknown but elevated due to process heat released from the industrial environment. Accuracy of the derived ages is limited mainly by this unknown infiltration temperature. Despite these difficulties the derived T/3He ages give clear hints for the improvement of the numerical model. Most probably ground water infiltration does not take place on the whole area as

  12. C. neoformans constitutes an ideal model organism to unravel the contribution of cellular aging to the virulence of chronic infections

    OpenAIRE

    Bouklas, Tejas; Fries, Bettina C.

    2013-01-01

    Aging affects all organisms, from unicellular yeasts to multicellular humans. Studies in model organisms demonstrate that the pathways that mediate the two forms of aging, replicative and chronological, are highly conserved. Most studies are focused on the effect of aging on an individual cell rather than a whole population. Complex longevity regulation, however, makes aging a highly adaptive trait that is subject to natural selection. Recent studies have shed light on the potential relevance...

  13. Characterization and modeling of the influence of artificial aging on the microstructural evolution of age-hardenable AlSi{sub 10}Mg(Cu) aluminum alloys

    Energy Technology Data Exchange (ETDEWEB)

    Larráyoz Izcara, X., E-mail: xabier.larrayoz.izcara@volkswagen.de [Group Research, Volkswagen AG, Berliner Ring 2, 38436 Wolfsburg (Germany); Guirao Blank, A., E-mail: alejandro.javier.guirao.blank@volkswagen.de [Group Research, Volkswagen AG, Berliner Ring 2, 38436 Wolfsburg (Germany); Pyczak, F., E-mail: florian.pyczak@hzg.de [Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Max Planck Str. 1, 21502 Geesthacht (Germany); Staron, P., E-mail: peter.staron@hzg.de [Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Max Planck Str. 1, 21502 Geesthacht (Germany); Schumann, S., E-mail: soenke.schumann@volkswagen.de [Group Research, Volkswagen AG, Berliner Ring 2, 38436 Wolfsburg (Germany); Huber, N., E-mail: norbert.huber@hzg.de [Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Max Planck Str. 1, 21502 Geesthacht (Germany)

    2014-07-29

    A comprehensive analysis of the effect of the artificial aging on the Mg{sub 2}Si precipitation distribution of the age-hardenable AlSi{sub 10}Mg(Cu) aluminum alloy from T6 to T7 condition is presented considering the influence of temperature and time of the aging conditions. A complete quantitative characterization of the strengthening distributions covering a broad range of aging conditions was obtained using the small angle neutron scattering (SANS) technique, complemented with high-resolution transmission electron microscopy (HTEM). This information was successfully used to fit Robson's precipitation model for the prediction of the precipitation distribution as a function of time and temperature. Based on the measured precipitation behavior a sigmoidal function of the interfacial energy was added to Robson's model. As a result a unique set of modeling parameters was obtained for the whole precipitation process and range of temperatures considered. Robson's model is shown to be a powerful tool for predicting the evolution of these nanometer-scale particles in industrial and complex aging processes, which are critical for designing new components based on the material requirements.

  14. Characterization and modeling of the influence of artificial aging on the microstructural evolution of age-hardenable AlSi10Mg(Cu) aluminum alloys

    International Nuclear Information System (INIS)

    A comprehensive analysis of the effect of the artificial aging on the Mg2Si precipitation distribution of the age-hardenable AlSi10Mg(Cu) aluminum alloy from T6 to T7 condition is presented considering the influence of temperature and time of the aging conditions. A complete quantitative characterization of the strengthening distributions covering a broad range of aging conditions was obtained using the small angle neutron scattering (SANS) technique, complemented with high-resolution transmission electron microscopy (HTEM). This information was successfully used to fit Robson's precipitation model for the prediction of the precipitation distribution as a function of time and temperature. Based on the measured precipitation behavior a sigmoidal function of the interfacial energy was added to Robson's model. As a result a unique set of modeling parameters was obtained for the whole precipitation process and range of temperatures considered. Robson's model is shown to be a powerful tool for predicting the evolution of these nanometer-scale particles in industrial and complex aging processes, which are critical for designing new components based on the material requirements

  15. Comparative modeling of Bronze Age land use in the Malatya Plain (Turkey)

    Science.gov (United States)

    Arıkan, Bülent; Restelli, Francesca Balossi; Masi, Alessia

    2016-03-01

    Computational modeling in archeology has proven to be a useful tool in quantifying changes in the paleoenvironment. This especially useful method combines data from diverse disciplines to answer questions focusing on the complex and non-linear aspects of human-environment interactions. The research presented here uses various proxy records to compare the changes in climate during the Bronze Age in the Malatya Plain in eastern Anatolia, which is situated at the northern extremity of northern Mesopotamia. Extensive agropastoral land use modeling was applied to three sites of different size and function in the Malatya Plain during the Early Bronze Age I period to simulate the varying scale and intensity of human impacts in relation to changes in the level of social organization, demography, and temporal length. The results suggest that even in land use types subjected to a light footprint, the scale and intensity of anthropogenic impacts change significantly in relation to the level of social organization.

  16. Parameter sensitivity analysis of a simplified electrochemical and thermal model for Li-ion batteries aging

    Science.gov (United States)

    Edouard, C.; Petit, M.; Forgez, C.; Bernard, J.; Revel, R.

    2016-09-01

    In this work, a simplified electrochemical and thermal model that can predict both physicochemical and aging behavior of Li-ion batteries is studied. A sensitivity analysis of all its physical parameters is performed in order to find out their influence on the model output based on simulations under various conditions. The results gave hints on whether a parameter needs particular attention when measured or identified and on the conditions (e.g. temperature, discharge rate) under which it is the most sensitive. A specific simulation profile is designed for parameters involved in aging equations in order to determine their sensitivity. Finally, a step-wise method is followed to limit the influence of parameter values when identifying some of them, according to their relative sensitivity from the study. This sensitivity analysis and the subsequent step-wise identification method show very good results, such as a better fitting of the simulated cell voltage with experimental data.

  17. Accommodating volume-constant age-dependent optical (AVOCADO) model of the crystalline GRIN lens.

    Science.gov (United States)

    Sheil, Conor J; Goncharov, Alexander V

    2016-05-01

    The purpose of this manuscript is to introduce a new age-dependent model of the human lens with two GRIN power distributions (axial and radial) that allow decoupling of its refractive power and axial optical path length. The aspect ratio of the lens core can be held constant under accommodation, as well as the lens volume by varying the asphericity of the lens external surfaces. The spherical aberration calculated by exact raytracing is shown to be in line with experimental data. The proposed model is compared to previous GRIN models from the literature, and it is concluded that the features of the new model will be useful for GRIN reconstruction in future experimental studies; in particular, studies of the accommodation-dependent properties of the ageing human eye. A proposed logarithmic model of the lens core enables decoupling of three fundamental optical characteristics of the lens, namely axial optical path length, optical power and third-order spherical aberration, without changing the external shape of the lens. Conversely, the near-surface GRIN structure conforms to the external shape of the lens, which is necessary for accommodation modelling. PMID:27231637

  18. Micro-dystrophin and follistatin co-delivery restores muscle function in aged DMD model

    OpenAIRE

    Rodino-Klapac, Louise R.; Janssen, Paul M. L.; Shontz, Kimberly M.; Canan, Benjamin; Montgomery, Chrystal L.; Griffin, Danielle; Heller, Kristin; Schmelzer, Leah; Handy, Chalonda; Clark, K. Reed; Sahenk, Zarife; Mendell, Jerry R.; Kaspar, Brian K.

    2013-01-01

    Pharmacologic strategies have provided modest improvement in the devastating muscle-wasting disease, Duchenne muscular dystrophy (DMD). Pre-clinical gene therapy studies have shown promise in the mdx mouse model; however, studies conducted after disease onset fall short of fully correcting muscle strength or protecting against contraction-induced injury. Here we examine the treatment effect on muscle physiology in aged dystrophic mice with significant disease pathology by combining two promis...

  19. Abundance Distributions in Artificial Life and Stochastic Models: "Age and Area" revisited

    OpenAIRE

    Adami, C.; Brown, C. T.; Haggerty, M.

    1995-01-01

    Using an artificial system of self-replicating strings, we show a correlation between the age of a genotype and its abundance that reflects a punctuated rather than gradual picture of evolution, as suggested long ago by Willis. In support of this correlation, we measure genotype abundance distributions and find universal coefficients. Finally, we propose a simple stochastic model which describes the dynamics of equilibrium periods and which correctly predicts most of the observed distributions.

  20. Abundance distributions in artificial life and stochastic models "age and area" revisited

    CERN Document Server

    Adami, C; Haggerty, M; Brown, C T; Haggerty, M

    1995-01-01

    Using an artificial system of self-replicating strings, we show a correlation between the age of a genotype and its abundance that reflects a punctuated rather than gradual picture of evolution, as suggested long ago by Willis. In support of this correlation, we measure genotype abundance distributions and find universal coefficients. Finally, we propose a simple stochastic model which describes the dynamics of equilibrium periods and which correctly predicts most of the observed distributions.

  1. A new age model for the early-middle Miocene in the North Alpine Foreland Basin

    Science.gov (United States)

    Reichenbacher, Bettina; Krijgsman, Wout; Pippèrr, Martina; Sant, Karin; Kirscher, Uwe

    2016-04-01

    The establishment of high-resolution age models for sedimentary successions is crucial for numerous research questions in the geosciences and related disciplines. Such models provide an absolute chronology that permits precise dating of depositional episodes and related processes such as mountain uplift or climate change. Recently, our work in the Miocene sediments of the North Alpine Foreland Basin (NAFB) has revealed a significantly younger age (16.6 Myr) for sediments that were thought to have been deposited 18 Myr ago. This implies that a fundamentally revised new age model is needed for the entire suite of lower-middle Miocene sedimentary rocks in the NAFB (20 to 15-Myr). Our new data also indicate that previously published reconstructions of early-middle Miocene palaeogeography, sedimentation dynamics, mountain uplift and climate change in the NAFB all require a critical review and revision. Further, the time-span addressed is of special interest, since it encompasses the onset of a global warming phase. However, it appears that a fundamentally revised new age model for the entire suite of lower-middle Miocene sedimentary rocks in the NAFB can only be achieved based on a 500 m deep drilling in the NAFB for which we currently seek collaboration partners to develop a grant application to the International Continental Deep Drilling Program (ICDP). Reference: Reichenbacher, B., W. Krijgsman, Y. Lataster, M. Pippèrr, C. G. C. Van Baak, L. Chang, D. Kälin, J. Jost, G. Doppler, D. Jung, J. Prieto, H. Abdul Aziz, M. Böhme, J. Garnish, U. Kirscher, and V. Bachtadse. 2013. A new magnetostratigraphic framework for the Lower Miocene (Burdigalian/Ottnangian, Karpatian) in the North Alpine Foreland Basin. Swiss Journal of Geosciences 106:309-334.

  2. Lithium prevents parkinsonian behavioral and striatal phenotypes in an aged parkin mutant transgenic mouse model

    OpenAIRE

    LIEU, CHRISTOPHER A.; Dewey, Colleen M.; Chinta, Shankar J.; Rane, Anand; Rajagopalan, Subramanian; Batir, Sean; Kim, Yong-Hwan; Julie K. Andersen

    2014-01-01

    Lithium has long been used as a treatment for the psychiatric disease bipolar disorder. However, previous studies suggest that lithium provides neuroprotective effects in neurodegenerative diseases such as Parkinson’s disease (PD) and Alzheimer’s disease. The exact mechanism by which lithium exerts these effects still remains unclear. In the present study, we evaluated the effects of low-dose lithium treatment in an aged mouse model expressing a parkin mutation within dopaminergic neurons. We...

  3. Type 2 diabetes model TSOD mouse is exposed to oxidative stress at young age

    OpenAIRE

    Murotomi, Kazutoshi; Umeno, Aya; Yasunaga, Mayu; Shichiri, Mototada; Ishida, Noriko; Abe, Hiroko; Yoshida, Yasukazu; Nakajima, Yoshihiro

    2014-01-01

    Tsumura Suzuki Obese Diabetes (TSOD) mouse, a model of obese type 2 diabetes, older than around 11 weeks of age develops diabetic phenotypes. Previous studies have indicated that the development of diabetes is partly due to three loci associated with body weight and glucose homeostasis. However, little is known about the initial events triggering the development of the diabetic phenotypes in TSOD mouse. Here, we investigated the alteration of diabetes-related parameters, including the levels ...

  4. Longitudinal Examination of the Exercise and Self-Esteem Model in Middle-Aged Women

    OpenAIRE

    Elavsky, Steriani

    2010-01-01

    This 2-year prospective study examined the exercise and self-esteem model in middle-aged women (N = 143) previously enrolled in a randomized controlled exercise trial. Across the 2-year period, increases in physical activity (PA) and self-efficacy and reductions in body mass index (BMI) were associated with improved subdomain self-perceptions relative to physical condition, and reductions in BMI were associated with improved subdomain self-perceptions relative to physical condition and body a...

  5. Comparison between Numerical and Simulation Methods for Age-dependent Branching Models with Immigration

    OpenAIRE

    Martinez, R.; Slavtchova-Bojkova, M.

    2005-01-01

    2000 Mathematics Subject Classification: primary: 60J80, 60J85, secondary: 62M09, 92D40 This work aims to provide and to compare numerical computation and simulation method to estimate the distribution of some relevant variables related to an age-dependent model allowing immigration at state zero. Specifically, we analyze the behaviour of the following variables: the extinction time and the waiting time for the beginning of the survival of population forever. They are strongly related to t...

  6. Consideration of age-dependent radium retention in people on the basis of the beagle model

    International Nuclear Information System (INIS)

    Skeletal calcification as a function of age has been estimated for human females on the basis of the beagle model. The interspecies scaling of radium retention characteristics has been described in terms of skeletal calcium addition rates for beagles and humans. radium retention in humans exposed to less than 200 μCi was greatest in individuals who were less than 18 years old when exposed

  7. Prediction of residual stress due to early age behaviour of massive concrete structures: on site experiments and macroscopic modelling

    CERN Document Server

    Zreiki, Jihad; Chaouche, Mohend; Moranville, Micheline

    2008-01-01

    Early age behaviour of concrete is based on complex multi-physical and multiscale phenomena. The predication of both cracking risk and residual stresses in hardened concrete structures is still a challenging task. We propose in this paper a practical method to characterize in the construction site the material parameters and to identify a macroscopic model from simple tests. We propose for instance to use a restrained shrinkage ring test to identify a basic early age creep model based on a simple ageing visco-elastic Kelvin model. The strain data obtained from this test can be treated through an early age finite element incremental procedure such that the fitting parameters of the creep law can be quickly identified. The others properties of concrete have been measured at different ages (elastic properties, hydration kinetics, and coefficient of thermal expansion). From the identified early age model, we computed the temperature rise and the stress development in a non reinforced concrete stress for nuclear w...

  8. Ngram time series model to predict activity type and energy cost from wrist, hip and ankle accelerometers: implications of age

    Science.gov (United States)

    Strath, Scott J; Kate, Rohit J; Keenan, Kevin G; Welch, Whitney A; Swartz, Ann M

    2016-01-01

    To develop and test time series single site and multi-site placement models, we used wrist, hip and ankle processed accelerometer data to estimate energy cost and type of physical activity in adults. Ninety-nine subjects in three age groups (18–39, 40–64, 65 + years) performed 11 activities while wearing three triaxial accelereometers: one each on the non-dominant wrist, hip, and ankle. During each activity net oxygen cost (METs) was assessed. The time series of accelerometer signals were represented in terms of uniformly discretized values called bins. Support Vector Machine was used for activity classification with bins and every pair of bins used as features. Bagged decision tree regression was used for net metabolic cost prediction. To evaluate model performance we employed the jackknife leave-one-out cross validation method. Single accelerometer and multi-accelerometer site model estimates across and within age group revealed similar accuracy, with a bias range of −0.03 to 0.01 METs, bias percent of −0.8 to 0.3%, and a rMSE range of 0.81–1.04 METs. Multi-site accelerometer location models improved activity type classification over single site location models from a low of 69.3% to a maximum of 92.8% accuracy. For each accelerometer site location model, or combined site location model, percent accuracy classification decreased as a function of age group, or when young age groups models were generalized to older age groups. Specific age group models on average performed better than when all age groups were combined. A time series computation show promising results for predicting energy cost and activity type. Differences in prediction across age group, a lack of generalizability across age groups, and that age group specific models perform better than when all ages are combined needs to be considered as analytic calibration procedures to detect energy cost and type are further developed. PMID:26449155

  9. Ngram time series model to predict activity type and energy cost from wrist, hip and ankle accelerometers: implications of age.

    Science.gov (United States)

    Strath, Scott J; Kate, Rohit J; Keenan, Kevin G; Welch, Whitney A; Swartz, Ann M

    2015-11-01

    To develop and test time series single site and multi-site placement models, we used wrist, hip and ankle processed accelerometer data to estimate energy cost and type of physical activity in adults. Ninety-nine subjects in three age groups (18-39, 40-64, 65 +  years) performed 11 activities while wearing three triaxial accelereometers: one each on the non-dominant wrist, hip, and ankle. During each activity net oxygen cost (METs) was assessed. The time series of accelerometer signals were represented in terms of uniformly discretized values called bins. Support Vector Machine was used for activity classification with bins and every pair of bins used as features. Bagged decision tree regression was used for net metabolic cost prediction. To evaluate model performance we employed the jackknife leave-one-out cross validation method. Single accelerometer and multi-accelerometer site model estimates across and within age group revealed similar accuracy, with a bias range of -0.03 to 0.01 METs, bias percent of -0.8 to 0.3%, and a rMSE range of 0.81-1.04 METs. Multi-site accelerometer location models improved activity type classification over single site location models from a low of 69.3% to a maximum of 92.8% accuracy. For each accelerometer site location model, or combined site location model, percent accuracy classification decreased as a function of age group, or when young age groups models were generalized to older age groups. Specific age group models on average performed better than when all age groups were combined. A time series computation show promising results for predicting energy cost and activity type. Differences in prediction across age group, a lack of generalizability across age groups, and that age group specific models perform better than when all ages are combined needs to be considered as analytic calibration procedures to detect energy cost and type are further developed. PMID:26449155

  10. Age models for peat deposits on the basis of coupled lead-210 and radiocarbon data.

    Science.gov (United States)

    Piotrowska, Natalia; de Vleeschouwer, François; Sikorski, Jarosław; Sensuła, Barbara; Michczyński, Adam; Fiałkiewicz-Kozieł, Barbara; Palowski, Bernard

    2010-05-01

    The study presents three examples of age-model construction based on the results of 210Pb and 14C dating methods applied to peat deposits. The three sites are ombrotrophic peat bogs: the Misten (Belgium), Slowinskie Bloto (N Poland) and Puscizna Mala (S Poland). All sites have been subjected to multiproxy studies aimed at reconstructing paleoenvironment and human activity, covering the last 1500, 1300 and 1800 years, respectively (De Vleeschouwer et al. 2009A, 2009B, in prep., Fialkiewicz-Koziel, ongoing PhD). A detailed comparison between 210Pb and post-bomb 14C results in the Misten bog has also been carried out by Piotrowska et al. (2009). In all cores, the 210Pb activity was calculated using 210Po and 208Po activities after acid-extraction from bulk samples, subsequent deposition on silver discs and measurements by alpha spectrometry. Unsupported 210Pb was detected until 35cm in Slowinskie Bloto, 15cm in the Misten and 19cm in Puscizna Mala. Constant Rate of Supply (CRS) model was then applied to compute ages of each 1-cm core interval. For the Misten and Slowinskie Bloto, radiocarbon measurements were performed on selected aboveground plant macrofossils, mainly Sphagnum spp. or Calluna vulgaris, Erica tetralix, and Andromeda polyfolia. Radiocarbon ages were determined using accelerator mass spectrometry (AMS) after acid-alkali-acid wash, combustion, purification of carbon dioxide and graphitisation. For Puscizna Mala bulk samples were dated after chemical preparation of benzene for liquid scintillation counting (LSC) or CO2 for gas proportional counting (GPC). Radiocarbon calibration was undertaken using the Intcal04 calibration curve and OxCal 4 software. As a priori information the 210Pb-derived ages were used in a P_Sequence model (Bronk Ramsey, 2008). A number of dates characterized by low agreement with stratigraphical order had to be considered as outliers and rejected from the final age model. For building a continuous age models a non-linear approach

  11. Aging Model For Cane Fiberboard Overpack In The 9975 Shipping Package

    International Nuclear Information System (INIS)

    Many radioactive material shipping packages incorporate a cane fiberboard overpack for thermal insulation and impact resistance. Mechanical, thermal and physical properties have been measured on cane fiberboard following thermal aging in several temperature/humidity environments. Several of the measured properties change significantly over time in the more severe environments, while other properties are relatively constant. Changes in each of the properties have been fit to a model to allow predictions of degradation under various storage scenarios. Additional data continue to be collected to provide for future refinements to the model.

  12. Effects of IMOD™ and Angipars™ on mouse D-galactose-induced model of aging.

    Science.gov (United States)

    Ghanbari, Samane; Yonessi, Mahsa; Mohammadirad, Azadeh; Gholami, Mahdi; Baeeri, Maryam; Khorram-Khorshid, Hamid Reza; Gharibdoost, Farhad; Abdollahi, Mohammad

    2012-01-01

    The aim of this study was to evaluate the effects of two registered herbal drugs called IMOD and Angipars on mouse model. Aging was induced by D-galactose (500 mg/kg) administered to animals for 6 weeks through drinking water. Male BALB/c mice were randomly divided into 5 groups receiving D-galactose (D-galactose, 500 mg/kg) for 6 weeks; positive control (D-galactose [500 mg/kg] for 6 weeks + Vitamin E [200 mg/kg/day] intraperitoneally for 4 weeks); IMOD (D-galactose [500 mg/kg] for 6 weeks + IMOD [20 mg/kg/day] intraperitoneally for 4 weeks), Angipars (D-galactose [500 mg/kg] for 6 weeks + Angipars [2.1 mg/kg/day] by gavage for 4 weeks); and the fifth group that was sham and not given D-galactose. At the end of treatment, pro-inflammatory markers including tumor necrosis factor-α (TNF-α), interlukine-1β (IL-β), interlukine-6 (IL-6), Nuclear Factor-kappaB (NF-κb), total antioxidant power (TAP), lipid peroxides (LPO) and male sex hormones i.e. testosterone and dehydroepiandrosterone-sulfate (DHEA-S) were measured in the blood.Results showed that D-Galactose induces a significant oxidative stress and proinflammatory cascade of aging while both IMOD and Angipars recovered all of them. Interestingly, IMOD and Angipars were better than Vitamin E in improving male sex hormones in aged mice. This effect is so important and should be considered as an advantage although it cannot be explained with current knowledge. The conclusion is that IMOD and Angipars have marked anti-aging effect on D-galactose-induced model of aging. PMID:23351487

  13. Effects of IMOD™ and Angipars™ on mouse D-galactose-induced model of aging

    Directory of Open Access Journals (Sweden)

    Ghanbari Samane

    2012-10-01

    Full Text Available Abstract The aim of this study was to evaluate the effects of two registered herbal drugs called IMOD and Angipars on mouse model of. Aging was induced by D-galactose (500 mg/kg administered to animals for 6 weeks through drinking water. Male BALB/c mice were randomly divided into 5 groups receiving D-galactose (D-galactose, 500 mg/kg for 6 weeks; positive control (D-galactose [500 mg/kg] for 6 weeks + Vitamin E [200 mg/kg/day] intraperitoneally for 4 weeks; IMOD (D-galactose [500 mg/kg] for 6 weeks + IMOD [20 mg/kg/day] intraperitoneally for 4 weeks, Angipars (D-galactose [500 mg/kg] for 6 weeks + Angipars [2.1 mg/kg/day] by gavage for 4 weeks; and the fifth group that was sham and not given D-galactose. At the end of treatment, pro-inflammatory markers including tumor necrosis factor-α (TNF-α, interlukine-1β (IL-β, interlukine-6 (IL-6, Nuclear Factor-kappaB (NF-κb, total antioxidant power (TAP, lipid peroxides (LPO and male sex hormones i.e. testosterone and dehydroepiandrosterone-sulfate (DHEA-S were measured in the blood. Results showed that D-Galactose induces a significant oxidative stress and proinflammatory cascade of aging while both IMOD and Angipars recovered all of them. Interestingly, IMOD and Angipars were better than Vitamin E in improving male sex hormones in aged mice. This effect is so important and should be considered as an advantage although it cannot be explained with current knowledge. The conclusion is that IMOD and Angipars have marked anti-aging effect on D-galactose-induced model of aging.

  14. Effects of IMOD and Angipars on Mouse D-Galactose-Induced Model of Aging

    Directory of Open Access Journals (Sweden)

    Samane Ghanbari

    2012-10-01

    Full Text Available The aim of this study was to evaluate the effects of two registered herbal drugs called IMOD and Angipars on mouse model of. Aging was induced by D-galactose (500 mg/kgadministered to animals for 6 weeks through drinking water. Male BALB/c mice were randomly divided into 5 groups receiving D-galactose (D-galactose, 500 mg/kg for 6 weeks; positive control (D-galactose [500 mg/kg] for 6 weeks + Vitamin E [200 mg/kg/day]intraperitoneally for 4 weeks; IMOD (D-galactose [500 mg/kg] for 6 weeks + IMOD [20 mg/kg/day] intraperitoneally for 4 weeks, Angipars (D-galactose [500 mg/kg] for 6 weeks + Angipars [2.1 mg/kg/day] by gavage for 4 weeks; and the fifth group that was sham and not given D-galactose. At the end of treatment, pro-inflammatory markers including tumor necrosis factor-α (TNF-α, interlukine-1β (IL-β, interlukine-6 (IL-6, NF-kappaB (NF-κb, total antioxidant power (TAP, lipid peroxides (LPO and male sex hormones i.e.testosterone and dehydroepiandrosterone-sulfate (DHEA-S were measured in the blood.Results showed that D-Galactose induces a significant oxidative stress and proinflammatory cascade of aging while both IMOD and Angipars recovered all of them. Interestingly, IMOD and Angipars were better than Vitamin E in improving male sex hormones that were declined in aged mice. This effect is so important and should be considered as an advantage although it cannot be explained with current knowledge. The conclusion is that IMOD and Angipars have marked anti-aging effect on D-galactose-induced model of aging.

  15. Wistar rats: A forgotten model of age-related hearing loss

    Directory of Open Access Journals (Sweden)

    Juan Carlos Alvarado

    2014-03-01

    Full Text Available Age-related hearing loss (ARHL is one of the most frequent sensory impairments in senescence and is a source of important socio-economic consequences. Understanding the pathological responses that occur in the central auditory pathway of patients who suffer from this disability is vital to improve its diagnosis and treatment. Therefore, the goal of this study was to characterize age-related modifications in auditory brainstem responses (ABR and to determine whether these functional responses might be accompanied by an imbalance between excitation and inhibition in the cochlear nucleus of Wistar rats. To do so, ABR recordings at different frequencies and immunohistochemistry for the vesicular glutamate transporter 1 (VGLUT1 and the vesicular GABA transporter (VGAT in the ventral cochlear nucleus (VCN were performed in young, middle-aged and old male Wistar rats. The results demonstrate that there was a significant increase in the auditory thresholds, a significant decrease in the amplitudes and an increase in the latencies of the ABR waves as the age of the rat increased. Additionally, there were decreases in VGLUT1 and VGAT immunostaining in the VCN of older rats compared to younger rats. Therefore, the observed age-related decline in the magnitude of auditory evoked responses might be due in part to a reduction in markers of excitatory function; meanwhile, the concomitant reduction in both excitatory and inhibitory markers might reflect a common central alteration in animal models of ARLH. Together, these findings highlight the suitability of the Wistar rat as an excellent model to study ARHL.

  16. Probabilistic graphical models to deal with age estimation of living persons.

    Science.gov (United States)

    Sironi, Emanuele; Gallidabino, Matteo; Weyermann, Céline; Taroni, Franco

    2016-03-01

    Due to the rise of criminal, civil and administrative judicial situations involving people lacking valid identity documents, age estimation of living persons has become an important operational procedure for numerous forensic and medicolegal services worldwide. The chronological age of a given person is generally estimated from the observed degree of maturity of some selected physical attributes by means of statistical methods. However, their application in the forensic framework suffers from some conceptual and practical drawbacks, as recently claimed in the specialised literature. The aim of this paper is therefore to offer an alternative solution for overcoming these limits, by reiterating the utility of a probabilistic Bayesian approach for age estimation. This approach allows one to deal in a transparent way with the uncertainty surrounding the age estimation process and to produce all the relevant information in the form of posterior probability distribution about the chronological age of the person under investigation. Furthermore, this probability distribution can also be used for evaluating in a coherent way the possibility that the examined individual is younger or older than a given legal age threshold having a particular legal interest. The main novelty introduced by this work is the development of a probabilistic graphical model, i.e. a Bayesian network, for dealing with the problem at hand. The use of this kind of probabilistic tool can significantly facilitate the application of the proposed methodology: examples are presented based on data related to the ossification status of the medial clavicular epiphysis. The reliability and the advantages of this probabilistic tool are presented and discussed. PMID:25794687

  17. Aging into perceptual control: A Dynamic Causal Modeling for fMRI study of bistable perception

    Directory of Open Access Journals (Sweden)

    Ehsan eDowlati

    2016-03-01

    Full Text Available Aging is accompanied by stereotyped changes in functional brain activations, for example a cortical shift in activity patterns from posterior to anterior regions is one hallmark revealed by functional magnetic resonance imaging (fMRI of aging cognition. Whether these neuronal effects of aging could potentially contribute to an amelioration of or resistance to the cognitive symptoms associated with psychopathology remains to be explored. We used a visual illusion paradigm to address whether aging affects the cortical control of perceptual beliefs and biases. Our aim was to understand the effective connectivity associated with volitional control of ambiguous visual stimuli and to test whether greater top-down control of early visual networks emerged with advancing age. Using a bias training paradigm for ambiguous images we found that older participants (n = 16 resisted experimenter-induced visual bias compared to a younger cohort (n = 14 and that this resistance was associated with greater activity in prefrontal and temporal cortices. By applying Dynamic Causal Models for fMRI we uncovered a selective recruitment of top-down connections from the middle temporal to lingual gyrus by the older cohort during the perceptual switch decision following bias training. In contrast, our younger cohort did not exhibit any consistent connectivity effects but instead showed a loss of driving inputs to orbitofrontal sources following training. These findings suggest that perceptual beliefs are more readily controlled by top-down strategies in older adults and introduce age-dependent neural mechanisms that may be important for understanding aberrant belief states associated with psychopathology.

  18. Preparing the Workforce for Healthy Aging Programs: The Skills for Healthy Aging Resources and Programs (SHARP) Model

    Science.gov (United States)

    Frank, Janet C.; Altpeter, Mary; Damron-Rodriguez, JoAnn; Driggers, Joann; Lachenmayr, Susan; Manning, Colleen; Martinez, Dana M.; Price, Rachel M.; Robinson, Patricia

    2014-01-01

    Current public health and aging service agency personnel have little training in gerontology, and virtually no training in evidence-based health promotion and disease management programs for older adults. These programs are rapidly becoming the future of our community-based long-term care support system. The purpose of this project was to develop…

  19. Variance components models for physical activity with age as modifier: a comparative twin study in seven countries

    DEFF Research Database (Denmark)

    Vink, Jacqueline M; Boomsma, Dorret I; Medland, Sarah E;

    2011-01-01

    Physical activity is influenced by genetic factors whose expression may change with age. We employed an extension to the classical twin model that allows a modifier variable, age, to interact with the effects of the latent genetic and environmental factors. The model was applied to self-reported ...

  20. The Role of a Model's Age for Young Children's Imitation: A Research Review

    Science.gov (United States)

    Zmyj, Norbert; Seehagen, Sabine

    2013-01-01

    The influence of a model's age on young children's behaviour has been a subject of considerable debate among developmental theorists. Despite the recent surge of interest, controversy remains about the nature of peer influence in early life. This article reviews studies that investigated the influence of a model's age on young…

  1. Modeling short wave solar radiation using the JGrass-NewAge System

    Directory of Open Access Journals (Sweden)

    G. Formetta

    2012-12-01

    Full Text Available This paper presents two new modelling components based on the Object Modelling System v3 for the calculation of the shortwave incident radiation (R^sw↓ on complex topography settings, and the implementation of several ancillary tools. The first component, NewAGE-SwRB, accounts for slope, aspect, shadow and the topographical information of the sites, and use suitable parametrisation for obtaining the cloudless irradiance. A second component, NewAGE-DEC-MOD's is implemented to estimate the irradiance reduction due to the presence of clouds, according to three parameterisations. To obtain a working modelling composition, suitable to be compared with ground data at measurement stations, the two components are connected to a Kriging component, and, with the use of a further component NewAGE-V (verification package, the performance of modeled (R^sw↓ is quantitatively evaluated. The two components (and the various parametrisations they contain are tested using the data from three basins catchments, and some simple verification test is made to assess the goodness of the methods used. The components are part of a larger system, JGrass-NewAGE, their input and outputs are given as geometrical objects immediately visualisable in a GIS (for instance the companion uDig, and can be used seamlessly with the various modelling solutions available in JGrass-NewAGE for the estimation of long wave radiation, evapotranspiration, and snow melting, as well as stand-alone components to just estimate shortwave radiation for various uses. The modularity of the approach is shown to be extensible to more accurate physical-statistical studies aimed to assess in deep the components performances and extends spatially their results, without the necessity of recoding any part of the component but just

  2. Anti-ageing effects of a new Dimethylaminoethanol-based formulation on D-Galactose induced skin ageing model of rat

    Institute of Scientific and Technical Information of China (English)

    YAN Bing-jian; YUAN Feng; ZHAO Cai-ling; LIU Su

    2015-01-01

    Background Dimethylaminoethanol has been widely used to fight against wrinkles, in the field of aesthetic medicine there is an increasing demand for safe and effective Dimethylaminoethanol-based products to counteract the ageing process. Objective To evaluate the anti-ageing effects of a new DMAE-based formulation. Methods 30 male rats were randomly allocated into treatment,D-gal ageing modeland control groups, each of which contained ten rats. Treatment group and D-gal ageing model group were subcutaneously injected with D- galactose prepared in normal saline 125mg·kg-1·d-1 for 42d. Control groups were injected with normal saline for 42 d with same method and dose. From the 18th day,after shaving their hair,the treatment grouprats were injected thisnew DMAE-based formulation at a dose of 1ml per week for 4 weeks in the Dermis of two sides hip skin mark zone.Meanwhile,D-gal ageing model group rats were administrated the same volume of normal saline with same method. Skin specimens were obtained 3days after the last treatment. Dermal collagen density and dermal thickness were evaluated by H&E and Masson-trichrome staining. And mRNA expressions of TGFβ1, Smad3, Type I,Type III Pro-collagen,TIMP-1, MMP-1,were assessed by Real-time quantitative polymerase chain reaction. Results Dermal thickness, dermal collagen density and hydroxyproline content in treatment group increased significantly comparing with D-gal ageing model group. No differences were found in mRNA expression of MMP-1 and Type III Pro-collagen between the treatment group and D-gal ageing model group. In addition, mRNA expression of TGFβ1, Type I Pre-collagen , TIMP1 and smad3 in treatment group were significantly up-regulated in contrast with D-gal ageing model and control group. Conclusion This new DMAE-based formulationcould generate anti-ageing effects by activating collagen synthesisthrough TGF-β1/Smads signaling pathway.

  3. A ternary age-mixing model to explain contaminant occurrence in a deep supply well

    Science.gov (United States)

    Jurgens, Bryant; Bexfield, Laura M.; Eberts, Sandra

    2014-01-01

    The age distribution of water from a public-supply well in a deep alluvial aquifer was estimated and used to help explain arsenic variability in the water. The age distribution was computed using a ternary mixing model that combines three lumped parameter models of advection-dispersion transport of environmental tracers, which represent relatively recent recharge (post- 1950s) containing volatile organic compounds (VOCs), old intermediate depth groundwater (about 6500 years) that was free of drinking-water contaminants, and very old, deep groundwater (more than 21,000 years) containing arsenic above the USEPA maximum contaminant level of 10 µg/L. The ternary mixing model was calibrated to tritium, chloroflorocarbon-113, and carbon-14 (14C) concentrations that were measured in water samples collected on multiple occasions. Variability in atmospheric 14C over the past 50,000 years was accounted for in the interpretation of 14C as a tracer. Calibrated ternary models indicate the fraction of deep, very old groundwater entering the well varies substantially throughout the year and was highest following long periods of nonoperation or infrequent operation, which occured during the winter season when water demand was low. The fraction of young water entering the well was about 11% during the summer when pumping peaked to meet water demand and about 3% to 6% during the winter months. This paper demonstrates how collection of multiple tracers can be used in combination with simplified models of fluid flow to estimate the age distribution and thus fraction of contaminated groundwater reaching a supply well under different pumping conditions.

  4. Transit times and age distributions for reservoir models represented as nonlinear non-autonomuous systems

    Science.gov (United States)

    Müller, Markus; Meztler, Holger; Glatt, Anna; Sierra, Carlos

    2016-04-01

    We present theoretical methods to compute dynamic residence and transit time distributions for non-autonomous systems of pools governed by coupled nonlinear differential equations. Although transit time and age distributions have been used to describe reservoir models for a long time, a closer look to their assumptions reveals two major restrictions of generality in previous studies. First, the systems are assumed to be in equilibrium; and second, the equations under consideration are assumed to be linear. While both these assumptions greatly ease the computation and interpretation of transit time and age distributions they are not applicable to a wide range of problems. Moreover, the transfer of previous results learned from linear systems in steady state to the more complex nonlinear non-autonomous systems that do not even need to have equilibria, can be dangerously misleading. Fortunately the topic of time dependent age and transit time distributions has received some attention recently in hydrology, we aim to compute these distributions for systems of multiple reservoirs. We will discuss how storage selection functions can augment the information represented in an ODE system describing a system of reservoirs. We will present analytical and numerical algorithms and a Monte Carlo simulator to compute solutions for system transit time and age distributions for system-wide storage selection functions including the most simple, but important case of well mixed pools.

  5. EFFECTS OF AGE, DIETARY AND BEHAVIORAL ENRICHMENT ON BRAIN MITOCHONDRIA IN A CANINE MODEL OF HUMAN AGING

    OpenAIRE

    Head, E; Nukala, V. N.; Fenoglio, K.A.; Muggenburg, B. A.; Cotman, C W; Sullivan, P. G.

    2009-01-01

    Dogs develop cognitive decline and a progressive accumulation of oxidative damage. In a previous longitudinal study, we demonstrated that aged dogs treated with either an antioxidant diet or with behavioral enrichment show cognitive improvement. The antioxidant diet included cellular antioxidants (Vitamins E, C, fruits and vegetables) and mitochondrial co-factors (lipoic acid and carnitine). Behavioral enrichment consisted of physical exercise, social enrichment and cognitive training. We hyp...

  6. Age-period-cohort modelling of breast cancer incidence in the Nordic countries

    DEFF Research Database (Denmark)

    Rostgaard, K; Vaeth, M; Holst, H;

    2001-01-01

    The Nordic countries have experienced a steady increase in breast cancer incidence throughout the past 35 years. We analysed the incidence in Denmark, Finland, Norway and Sweden during the period 1958 to 1992 using age-period-cohort models and taking the systematic mammography screening into acco...... been exposed to an increasing load of cohort borne breast cancer risk factors not experienced to the same extent by Norwegian women, whereas they were seemingly subjected to the same period effects.......The Nordic countries have experienced a steady increase in breast cancer incidence throughout the past 35 years. We analysed the incidence in Denmark, Finland, Norway and Sweden during the period 1958 to 1992 using age-period-cohort models and taking the systematic mammography screening into...... in breast cancer incidence seen in the Nordic countries. The widespread practice of neglecting the period effects in age-period-cohort analysis of time trends in breast cancer incidence therefore probably needs reconsideration. A key finding was that Danish women born in the 20th century seem to have...

  7. Modeling the Mechanical Consequences of Age-Related Trabecular Bone Loss by XFEM Simulation

    Science.gov (United States)

    Fan, Ruoxun; Zhang, Xianbin; Liu, Jun; Jia, Zhengbin; Zhu, Dong

    2016-01-01

    The elderly are more likely to suffer from fracture because of age-related trabecular bone loss. Different bone loss locations and patterns have different effects on bone mechanical properties. Extended finite element method (XFEM) can simulate fracture process and was suited to investigate the effects of bone loss on trabecular bone. Age-related bone loss is indicated by trabecular thinning and loss and may occur at low-strain locations or other random sites. Accordingly, several ideal normal and aged trabecular bone models were created based on different bone loss locations and patterns; then, fracture processes from crack initiation to complete failure of these models were observed by XFEM; finally, the effects of different locations and patterns on trabecular bone were compared. Results indicated that bone loss occurring at low-strain locations was more detrimental to trabecular bone than that occurring at other random sites; meanwhile, the decrease in bone strength caused by trabecular loss was higher than that caused by trabecular thinning, and the effects of vertical trabecular loss on mechanical properties were more severe than horizontal trabecular loss. This study provided a numerical method to simulate trabecular bone fracture and distinguished different effects of the possible occurrence of bone loss locations and patterns on trabecular bone.

  8. Bias in the reporting of sex and age in biomedical research on mouse models.

    Science.gov (United States)

    Flórez-Vargas, Oscar; Brass, Andy; Karystianis, George; Bramhall, Michael; Stevens, Robert; Cruickshank, Sheena; Nenadic, Goran

    2016-01-01

    In animal-based biomedical research, both the sex and the age of the animals studied affect disease phenotypes by modifying their susceptibility, presentation and response to treatment. The accurate reporting of experimental methods and materials, including the sex and age of animals, is essential so that other researchers can build on the results of such studies. Here we use text mining to study 15,311 research papers in which mice were the focus of the study. We find that the percentage of papers reporting the sex and age of mice has increased over the past two decades: however, only about 50% of the papers published in 2014 reported these two variables. We also compared the quality of reporting in six preclinical research areas and found evidence for different levels of sex-bias in these areas: the strongest male-bias was observed in cardiovascular disease models and the strongest female-bias was found in infectious disease models. These results demonstrate the ability of text mining to contribute to the ongoing debate about the reproducibility of research, and confirm the need to continue efforts to improve the reporting of experimental methods and materials. PMID:26939790

  9. The relevance of parametric U-uptake models in ESR age calculations

    International Nuclear Information System (INIS)

    In the ESR dating three basic parametric U-uptake models have been applied for dating teeth: early U-uptake (EU: closed system), linear U-uptake (LU) and recent U-uptake (RU, it is assumed that the dose rate contribution of U in the dental tissues is zero). In many ESR dating publications it is still assumed that samples comply with one or the other parametric U-uptake model calculation or that their correct age lies somewhere between EU and LU. Observations of the spatial distribution of uranium in dental tissues show that it is difficult to predict any relationships between the relative uptake in the dental tissues. Combined U-series/ESR age estimates can give insights into the actual U-uptake. An evaluation of published data shows that for cave sites, a significant number of results fall outside the EU and LU bracket, while for open air sites, the majority of data are outside this bracket, particularly showing greatly delayed U-uptake. This may be due to changes in the hydrological system, leading to erosion which exposes the open air site. U-leaching has also been observed on samples from open air sites, in which case any reasonable age calculation is impossible.

  10. Systematic identification of yeast proteins extracted into model wine during aging on the yeast lees.

    Science.gov (United States)

    Rowe, Jeffrey D; Harbertson, James F; Osborne, James P; Freitag, Michael; Lim, Juyun; Bakalinsky, Alan T

    2010-02-24

    Total protein and protein-associated mannan concentrations were measured, and individual proteins were identified during extraction into model wines over 9 months of aging on the yeast lees following completion of fermentations by seven wine strains of Saccharomyces cerevisiae. In aged wines, protein-associated mannan increased about 6-fold (+/-66%), while total protein only increased 2-fold (+/-20%), which resulted in a significantly greater protein-associated mannan/total protein ratio for three strains. A total of 219 proteins were identified among all wine samples taken over the entire time course. Of the 17 "long-lived" proteins detected in all 9 month samples, 13 were cell wall mannoproteins, and four were glycolytic enzymes. Most cytosolic proteins were not detected after 6 months. Native mannosylated yeast invertase was assayed for binding to wine tannin and was found to have a 10-fold lower affinity than nonglycosylated bovine serum albumin. Enrichment of mannoproteins in the aged model wines implies greater solution stability than other yeast proteins and the possibility that their contributions to wine quality may persist long after bottling. PMID:20108898

  11. A Bayesian semiparametric multilevel survival modelling of age at first birth in Nigeria

    Directory of Open Access Journals (Sweden)

    Ezra Gayawan

    2013-06-01

    Full Text Available BACKGROUND The age at which childbearing begins influences the total number of children a woman bears throughout her reproductive period, in the absence of any active fertility control. For countries in sub-Saharan Africa where contraceptive prevalence rate is still low, younger ages at first birth tend to increase the number of children a woman will have thereby hindering the process of fertility decline. Research has also shown that early childbearing can endanger the health of the mother and her offspring, which can in turn lead to high child and maternal mortality. OBJECTIVE In this paper, an attempt was made to explore possible trends, geographical variation and determinants of timing of first birth in Nigeria, using the 1999 - 2008 Nigeria Demographic and Health Survey data sets. METHODS A structured additive survival model for continuous time data, an approach that simultaneously estimates the nonlinear effect of metrical covariates, fixed effects, spatial effects and smoothing parameters within a Bayesian context in one step is employed for all estimations. All analyses were carried out using BayesX - a software package for Bayesian modelling techniques. RESULTS Results from this paper reveal that variation in age at first birth in Nigeria is determined more by individual household than by community, and that substantial geographical variations in timing of first birth also exist. COMMENTS These findings can guide policymakers in identifying states or districts that are associated with significant risk of early childbirth, which can in turn be used in designing effective strategies and in decision making.

  12. Optimizing a Male Reproductive Aging Mouse Model by d-Galactose Injection

    Directory of Open Access Journals (Sweden)

    Chun-Hou Liao

    2016-01-01

    Full Text Available The d-galactose (d-gal-injected animal model, which is typically established by administering consecutive subcutaneous d-gal injections to animals for approximately six or eight weeks, has been frequently used for aging research. In addition, this animal model has been demonstrated to accelerate aging in the brain, kidneys, liver and blood cells. However, studies on aging in male reproductive organs that have used this animal model remain few. Therefore, the current study aimed to optimize a model of male reproductive aging by administering d-gal injections to male mice and to determine the possible mechanism expediting senescence processes during spermatogenesis. In this study, C57Bl/6 mice were randomized into five groups (each containing 8–10 mice according to the daily intraperitoneal injection of vehicle control or 100 or 200 mg/kg dosages of d-gal for a period of six or eight weeks. First, mice subjected to d-gal injections for six or eight weeks demonstrated considerably decreased superoxide dismutase activity in the serum and testis lysates compared to those in the control group. The lipid peroxidation in testis also increased in the d-gal-injected groups. Furthermore, the d-gal-injected groups exhibited a decreased ratio of testis weight/body weight and sperm count compared to the control group. The percentages of both immotile sperm and abnormal sperm increased considerably in the d-gal-injected groups compared to those of the control group. To determine the genes influenced by the d-gal injection during murine spermatogenesis, a c-DNA microarray was conducted to compare testicular RNA samples between the treated groups and the control group. The d-gal-injected groups exhibited RNA transcripts of nine spermatogenesis-related genes (Cycl2, Hk1, Pltp, Utp3, Cabyr, Zpbp2, Speer2, Csnka2ip and Katnb1 that were up- or down-regulated by at least two-fold compared to the control group. Several of these genes are critical for forming sperm

  13. A functional group oxidation model (FGOM for SOA formation and aging

    Directory of Open Access Journals (Sweden)

    X. Zhang

    2013-06-01

    Full Text Available Secondary organic aerosol (SOA formation from a volatile organic compound (VOC involves multiple generations of oxidation that include functionalization and fragmentation of the parent carbon backbone and likely particle-phase oxidation and/or accretion reactions. Despite the typical complexity of the detailed molecular mechanism of SOA formation and aging, a relatively small number of functional groups characterize the oxidized molecules that constitute SOA. Given the carbon number and set of functional groups, the volatility of the molecule can be estimated. We present here a functional group oxidation model (FGOM that represents the process of SOA formation and aging. The FGOM contains a set of parameters that are to be determined by fitting of the model to laboratory chamber data: total organic aerosol concentration, and O : C and H : C atomic ratios. The sensitivity of the model prediction to variation of the adjustable parameters allows one to assess the relative importance of various pathways involved in SOA formation. An analysis of SOA formation from the high- and low-NOx photooxidation of four C12 alkanes (n-dodecane, 2-methylundecane, hexylcyclohexane, and cyclododecane using the FGOM is presented, and comparison with the statistical oxidation model (SOM of Cappa et al. (2013 is discussed.

  14. A Functional Group Oxidation Model (FGOM for SOA formation and aging

    Directory of Open Access Journals (Sweden)

    X. Zhang

    2012-12-01

    Full Text Available Secondary organic aerosol (SOA formation from a volatile organic compound (VOC involves multiple generations of oxidation that include functionalization and fragmentation of the parent carbon backbone and, likely, particle-phase oxidation and/or accretion reactions. Despite the typical complexity of the detailed molecular mechanism of SOA formation and aging, a relatively small number of functional groups characterize the oxidized molecules that constitute SOA. Given the carbon number and set of functional groups, the volatility of the molecule can be estimated. We present here a Functional Group Oxidation Model (FGOM that represents the process of SOA formation and aging. The FGOM contains a set of parameters that are to be determined by fitting of the model to laboratory chamber data: total organic aerosol concentration, and O:C and H:C atomic ratios. The sensitivity of the model prediction to variation of the adjustable parameters allows one to assess the relative importance of various pathways involved in SOA formation. An analysis of SOA formation from the high- and low-NOx photooxidation of four C12 alkanes (n-dodecane, 2-methylundecane, hexylcyclohexane, and cyclododecane using the FGOM is presented, and comparison with the Statistical Oxidation Model (SOM of Cappa et al. (2012 is discussed.

  15. Sizes and ages of SDSS ellipticals: Comparison with hierarchical galaxy formation models

    CERN Document Server

    Shankar, Francesco; Bernardi, Mariangela; Dai, Xinyu; Hyde, Joseph B; Sheth, Ravi K

    2009-01-01

    In a sample of about 45,700 early-type galaxies extracted from SDSS, we find that the shape, normalization, and dispersion around the mean size-stellar mass relation is the same for young and old systems, provided the stellar mass is greater than 3*10^10 Msun. This is difficult to reproduce in pure passive evolution models, which generically predict older galaxies to be much more compact than younger ones of the same stellar mass. However, this aspect of our measurements is well reproduced by hierarchical models of galaxy formation. Whereas the models predict more compact galaxies at high redshifts, subsequent minor, dry mergers increase the sizes of the more massive objects, resulting in a flat size-age relation at the present time. At lower masses, the models predict that mergers are less frequent, so that the expected anti-correlation between age and size is not completely erased. This is in good agreement with our data: below 3*10^10 Msun, the effective radius R_e is a factor of ~2 lower for older galaxie...

  16. ISSLS PRIZE WINNER: INHIBITION OF NF-κB ACTIVITY AMELIORATES AGE-ASSOCIATED DISC DEGENERATION IN A MOUSE MODEL OF ACCELERATED AGING

    Science.gov (United States)

    Nasto, Luigi A.; Seo, Hyoung-Yeon; Robinson, Andria R.; Tilstra, Jeremy S.; Clauson, Cheryl L.; Sowa, Gwendolyn A.; Ngo, Kevin; Dong, Qing; Pola, Enrico; Lee, Joon Y.; Niedernhofer, Laura J.; Kang, James D.; Robbins, Paul D.; Vo, Nam V.

    2012-01-01

    Study Design NF-κB activity was pharmacologically and genetically blocked in an accelerated aging mouse model to mitigate age-related disc degenerative changes. Objective To study the mediatory role of NF-κB signaling pathway in age-dependent intervertebral disc degeneration. Summary of Background Data Aging is a major contributor to intervertebral disc degeneration (IDD), but the molecular mechanism behind this process is poorly understood. NF-κB is a family of transcription factors which play a central role in mediating cellular response to damage, stress, and inflammation. Growing evidence implicates chronic NF-κB activation as a culprit in many aging-related diseases, but its role in aging-related IDD has not been adequately explored. We studied the effects of NF-κB inhibition on IDD using a DNA repair-deficient mouse model of accelerated aging (Ercc1-/Δ mice) previously been reported to exhibit age-related IDD. Methods Systemic inhibition of NF-κB activation was achieved either genetically by deletion of one allele of the NF-κB subunit p65 (Ercc1-/Δp65+/- mice) or pharmacologically by chronic intra-peritoneal administration of the Nemo Binding Domain (8K-NBD) peptide to block the formation of the upstream activator of NF-κB, IκB Inducible Kinase (IKK), in Ercc1-/Δ mice. Disc cellularity, total proteoglycan content and proteoglycan synthesis of treated mice and untreated controls were assessed. Results Decreased disc matrix proteoglycan content, a hallmark feature of IDD, and elevated disc NF-κB activity were observed in discs of progeroid Ercc1-/Δ mice and naturally aged wild-type compared to young WT mice. Systemic inhibition of NF-κB by the 8K-NBD peptide in Ercc1-/Δ mice increased disc proteoglycan synthesis and ameriolated loss disc cellularity and matrix proteoglycan. These results were confirmed genetically by using the p65 haploinsufficient Ercc1-/Δp65+/- mice. Conclusion These findings demonstrate that the IKK/NF-κB signaling pathway

  17. Methodology for the Incorporation of Passive Component Aging Modeling into the RAVEN/ RELAP-7 Environment

    Energy Technology Data Exchange (ETDEWEB)

    Mandelli, Diego; Rabiti, Cristian; Cogliati, Joshua; Alfonsi, Andrea; Askin Guler; Tunc Aldemir

    2014-11-01

    Passive system, structure and components (SSCs) will degrade over their operation life and this degradation may cause to reduction in the safety margins of a nuclear power plant. In traditional probabilistic risk assessment (PRA) using the event-tree/fault-tree methodology, passive SSC failure rates are generally based on generic plant failure data and the true state of a specific plant is not reflected realistically. To address aging effects of passive SSCs in the traditional PRA methodology [1] does consider physics based models that account for the operating conditions in the plant, however, [1] does not include effects of surveillance/inspection. This paper represents an overall methodology for the incorporation of aging modeling of passive components into the RAVEN/RELAP-7 environment which provides a framework for performing dynamic PRA. Dynamic PRA allows consideration of both epistemic and aleatory uncertainties (including those associated with maintenance activities) in a consistent phenomenological and probabilistic framework and is often needed when there is complex process/hardware/software/firmware/ human interaction [2]. Dynamic PRA has gained attention recently due to difficulties in the traditional PRA modeling of aging effects of passive components using physics based models and also in the modeling of digital instrumentation and control systems. RAVEN (Reactor Analysis and Virtual control Environment) [3] is a software package under development at the Idaho National Laboratory (INL) as an online control logic driver and post-processing tool. It is coupled to the plant transient code RELAP-7 (Reactor Excursion and Leak Analysis Program) also currently under development at INL [3], as well as RELAP 5 [4]. The overall methodology aims to: • Address multiple aging mechanisms involving large number of components in a computational feasible manner where sequencing of events is conditioned on the physical conditions predicted in a simulation

  18. Joint Modelling of Survival and Emergency Medical Care Usage in Spanish Insureds Aged 65+

    Science.gov (United States)

    2016-01-01

    Background We study the longevity and medical resource usage of a large sample of insureds aged 65 years or older drawn from a large health insurance dataset. Yearly counts of each subject's emergency room and ambulance service use and hospital admissions are made. Occurrence of mortality is also monitored. The study aims to capture the simultaneous dependence between their demand for healthcare and survival. Methods We demonstrate the benefits of taking a joint approach to modelling longitudinal and survival processes by using a large dataset from a Spanish medical mutual company. This contains historical insurance information for 39,137 policyholders aged 65+ (39.5% men and 60.5% women) across the eight-year window of the study. The joint model proposed incorporates information on longitudinal demand for care in a weighted cumulative effect that places greater emphasis on more recent than on past service demand. Results A strong significant and positive relationship between the exponentially weighted demand for emergency, ambulance and hospital services is found with risk of death (alpha = 1.462, p < 0.001). Alternative weighting specifications are tested, but in all cases they show that a joint approach indicates a close connection between health care demand and time-to-death. Additionally, the model allows us to predict individual survival curves dynamically as new information on demand for services becomes known. Conclusions The joint model fitted demonstrates the utility of analysing demand for medical services and survival simultaneously. Likewise, it allows the personalized prediction of survival in advanced age subjects. PMID:27073868

  19. Constraining stellar population models - I. Age, metallicity, and abundance pattern compilation for Galactic globular clusters

    CERN Document Server

    Roediger, Joel C; Graves, Genevieve; Schiavon, Ricardo

    2013-01-01

    We present an extenstive literature compilation of age, metallicity, and chemical abundance pattern information for the 41 Galactic globular clusters (GGCs) studied by Schiavon et al. (2005). Our compilation constitutes a notable improvement over previous similar work, particularly in terms of chemical abundances. Its primary purpose is to enable detailed evaluations of and refinements to stellar population synthesis models designed to recover the above information for unresolved stellar systems based on their integrated spectra. However, since the Schiavon sample spans a wide range of the known GGC parameter space, our compilation may also benefit investigations related to a variety of astrophysical endeavours, such as the early formation of the Milky Way, the chemical evolution of GGCs, and stellar evolution and nucleosynthesis. For instance, we confirm with our compiled data that the GGC system has a bimodal metallicity distribution and is uniformly enhanced in the alpha-elements. When paired with the ages...

  20. Thermal analysis of pentaerythritol tetranitrate and development of a powder aging model

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Geoffrey W [Los Alamos National Laboratory; Sandstrom, Mary M [Los Alamos National Laboratory; Giambra, Anna M [Los Alamos National Laboratory; Archuleta, Jose G [Los Alamos National Laboratory; Monroe, Deirde C [Los Alamos National Laboratory

    2009-01-01

    We have applied a range of different physical and thermal analysis techniques to characterize the thermal evolution of the specific surface area of pentaerythritol tetranitrate (PETN) powders. Using atomic force microscopy we have determined that the mass transfer mechanism leading to powder coarsening is probably sublimation and redeposition of PETN. Using thermogravimetric analysis we have measured vapor pressures of PETN powders whose aging will be simulated in future work. For one specific powder we have constructed an empirical model of the coarsening that is fit to specific surface area measurements at 60 C to 70 C to provide predictive capability of that powder's aging. Modulated differential scanning calorimetry and mass spectroscopy measurements highlight some of the thermal behavior of the powders and suggest that homologue-based eutectics and impurities are localized in the powder particles.

  1. Modelling the Effects of Ageing Time of Starch on the Enzymatic Activity of Three Amylolytic Enzymes

    Directory of Open Access Journals (Sweden)

    Nelson P. Guerra

    2012-01-01

    Full Text Available The effect of increasing ageing time (t of starch on the activity of three amylolytic enzymes (Termamyl, San Super, and BAN was investigated. Although all the enzymatic reactions follow michaelian kinetics, vmax decreased significantly (P<0.05 and KM increased (although not always significantly with the increase in t. The conformational changes produced in the starch chains as a consequence of the ageing seemed to affect negatively the diffusivity of the starch to the active site of the enzymes and the release of the reaction products to the medium. A similar effect was observed when the enzymatic reactions were carried out with unaged starches supplemented with different concentrations of gelatine [G]. The inhibition in the amylolytic activities was best mathematically described by using three modified forms of the Michaelis-Menten model, which included a term to consider, respectively, the linear, exponential, and hyperbolic inhibitory effects of t and [G].

  2. Toward an animal model of extinction-induced despair: focus on aging and physiological indices.

    Science.gov (United States)

    Huston, Joseph P; Schulz, Daniela; Topic, Bianca

    2009-08-01

    Behaviors that are under the control of positive or negative reinforcers undergo extinction when the anticipated reward/reinforcer is withheld. Despair, an important symptom of environmentally determined depression in humans, can be generated by extinction, or the failure of expected reward to accrue. Although well known to clinicians dealing with depressive patients, an animal model has not been available for extinction-induced depression. We have made a beginning towards validating such a model, based on the extinction of negatively reinforced behavior in the rat, i.e., upon removal of the possibility to escape onto a safety platform in the water maze. As a marker for despair, we employed behavioral immobility, i.e., the cessation of swimming in the attempt to find safety from the water, presumably, a type of learned helplessness. This measure was sensitive to antidepressants and correlated with neurotransmitter contents, neurotrophins and hypothalamus-pituitary adrenal axis markers in selected sites of the brain. Given that some cases of depression in the elderly may be biologically distinct from others and from early-onset depression, and since particularly the aged are prone to experience extinction-induced despair, we compared aged (ca. 24 months old) animals with adults in most of our studies. We found a number of distinct differences in behavioral and biological measures, indicative of differences in propensity to, as well as response to, extinction-induced despair between aged and adults. Our results add to the body of evidence for differences in the neurobiological substrates of depressive disorders between aged and adults, with the implication for the requirement of different treatment strategies in these two populations. PMID:19350220

  3. Reliability of some ageing nuclear power plant system: a simple stochastic model

    International Nuclear Information System (INIS)

    The random number of failure-related events in certain repairable ageing systems, like certain nuclear power plant components, during a given time interval, may be often modelled by a compound Poisson distribution. One of these is the Polya-Aeppli distribution. The derivation of a stationary Polya-Aeppli distribution as a limiting distribution of rare events for stationary Bernouilli trials with first order Markov dependence is considered. But if the parameters of the Polya-Aeppli distribution are suitable time functions, we could expect that the resulting distribution would allow us to take into account the distribution of failure-related events in an ageing system. Assuming that a critical number of damages produce an emergent failure, the above mentioned results can be applied in a reliability analysis. It is natural to ask under what conditions a Polya-Aeppli distribution could be a limiting distribution for non-homogeneous Bernouilli trials with first order Markov dependence. In this paper this problem is analyzed and possible applications of the obtained results to ageing or deteriorating nuclear power plant components are considered. The two traditional ways of modelling repairable systems in reliability theory: the 'as bad as old' concept, that assumes that the replaced component is exactly under the same conditions as was the aged component before failure, and the 'as good as new' concept, that assumes that the new component is under the same conditions of the replaced component when it was new, are briefly discussed in relation with the findings of the present work. (author)

  4. Fourth-Order Method for Numerical Integration of Age- and Size-Structured Population Models

    Energy Technology Data Exchange (ETDEWEB)

    Iannelli, M; Kostova, T; Milner, F A

    2008-01-08

    In many applications of age- and size-structured population models, there is an interest in obtaining good approximations of total population numbers rather than of their densities. Therefore, it is reasonable in such cases to solve numerically not the PDE model equations themselves, but rather their integral equivalents. For this purpose quadrature formulae are used in place of the integrals. Because quadratures can be designed with any order of accuracy, one can obtain numerical approximations of the solutions with very fast convergence. In this article, we present a general framework and a specific example of a fourth-order method based on composite Newton-Cotes quadratures for a size-structured population model.

  5. Age-related decrease in the mitochondrial sirtuin deacetylase Sirt3 expression associated with ROS accumulation in the auditory cortex of the mimetic aging rat model.

    Directory of Open Access Journals (Sweden)

    Lingling Zeng

    Full Text Available Age-related dysfunction of the central auditory system, also known as central presbycusis, can affect speech perception and sound localization. Understanding the pathogenesis of central presbycusis will help to develop novel approaches to prevent or treat this disease. In this study, the mechanisms of central presbycusis were investigated using a mimetic aging rat model induced by chronic injection of D-galactose (D-Gal. We showed that malondialdehyde (MDA levels were increased and manganese superoxide dismutase (SOD2 activity was reduced in the auditory cortex in natural aging and D-Gal-induced mimetic aging rats. Furthermore, mitochondrial DNA (mtDNA 4834 bp deletion, abnormal ultrastructure and cell apoptosis in the auditory cortex were also found in natural aging and D-Gal mimetic aging rats. Sirt3, a mitochondrial NAD+-dependent deacetylase, has been shown to play a crucial role in controlling cellular reactive oxygen species (ROS homeostasis. However, the role of Sirt3 in the pathogenesis of age-related central auditory cortex deterioration is still unclear. Here, we showed that decreased Sirt3 expression might be associated with increased SOD2 acetylation, which negatively regulates SOD2 activity. Oxidative stress accumulation was likely the result of low SOD2 activity and a decline in ROS clearance. Our findings indicate that Sirt3 might play an essential role, via the mediation of SOD2, in central presbycusis and that manipulation of Sirt3 expression might provide a new approach to combat aging and oxidative stress-related diseases.

  6. Dysregulation of Mitochondrial Quality Control Processes Contribute to Sarcopenia in a Mouse Model of Premature Aging

    OpenAIRE

    Joseph, Anna-Maria; Adhihetty, Peter J; Wawrzyniak, Nicholas R.; Stephanie E. Wohlgemuth; Picca, Anna; Kujoth, Gregory C.; Prolla, Tomas A.; Leeuwenburgh, Christiaan

    2013-01-01

    Mitochondrial DNA (mtDNA) mutations lead to decrements in mitochondrial function and accelerated rates of these mutations has been linked to skeletal muscle loss (sarcopenia). The purpose of this study was to investigate the effect of mtDNA mutations on mitochondrial quality control processes in skeletal muscle from animals (young; 3–6 months and older; 8–15 months) expressing a proofreading-deficient version of mtDNA polymerase gamma (PolG). This progeroid aging model exhibits elevated mtDNA...

  7. Effects of IMOD™ and Angipars™ on mouse D-galactose-induced model of aging

    OpenAIRE

    Samane Ghanbari; Mahsa Yonessi; Azadeh Mohammadirad; Mahdi Gholami; Maryam Baeeri; Hamid Reza Khorram-Khorshid; Farhad Gharibdoost; Mohammad Abdollahi

    2012-01-01

    Abstract The aim of this study was to evaluate the effects of two registered herbal drugs called IMOD and Angipars on mouse model of. Aging was induced by D-galactose (500 mg/kg) administered to animals for 6 weeks through drinking water. Male BALB/c mice were randomly divided into 5 groups receiving D-galactose (D-galactose, 500 mg/kg) for 6 weeks; positive control (D-galactose [500 mg/kg] for 6 weeks + Vitamin E [200 mg/kg/day] intraperitoneally for 4 weeks); IMOD (D-galactose [500 mg/kg] f...

  8. Modeling of Late Blooming Phases and Precipitation Kinetics in Aging Reactor Pressure Vessel (RPV) Steels

    Energy Technology Data Exchange (ETDEWEB)

    Yongfeng Zhang; Pritam Chakraborty; S. Bulent Biner

    2013-09-01

    The principle work at the atomic scale is to develop a predictive quantitative model for the microstructure evolution of RPV steels under thermal aging and neutron radiation. We have developed an AKMC method for the precipitation kinetics in bcc-Fe, with Cu, Ni, Mn and Si being the alloying elements. In addition, we used MD simulations to provide input parameters (if not available in literature). MMC simulations were also carried out to explore the possible segregation/precipitation morphologies at the lattice defects. First we briefly describe each of the simulation algorithms, then will present our results.

  9. Aging and orthopedics: how a lifespan development model can inform practice and research.

    Science.gov (United States)

    Gautreau, Sylvia; Gould, Odette N; Forsythe, Michael E

    2016-08-01

    Orthopedic surgical care, like all health care today, is in flux owing to an aging population and to chronic medical conditions leading to an increased number of people with illnesses that need to be managed over the lifespan. The result is an ongoing shift from curing acute illnesses to the management and care of chronic illness and conditions. Theoretical models that provide a useful and feasible vision for the future of health care and health care research are needed. This review discusses how the lifespan development model used in some disciplines within the behavioural sciences can be seen as an extension of the biopsychosocial model. We posit that the lifespan development model provides useful perspectives for both orthopedic care and research. We present key concepts and recommendations, and we discuss how the lifespan development model can contribute to new and evolving perspectives on orthopedic outcomes and to new directions for research. We also offer practical guidelines on how to implement the model in orthopedic practice. PMID:27240129

  10. Some considerations in applying stock-recruitment models to multiple-age spawning populations

    International Nuclear Information System (INIS)

    Several approaches used during the Hudson River power plant hearings (1977-1980) to permit quantitative estimation of the impact of power plant operation on the river's striped bass population are presented. The Ricker stock-recruitment model was adopted as a starting point to provide a reasonable working conceptualization of the stock-recruitment processes operating in this river. This model was then modified in a variety of ways to reflect multiple-age spawning by striped bass, and the results were fit to data on the river's commercial striped bass catch and effort, organized to reflect certain average age distribution parameters. Environmental variation in the system, represented in an overall fashion by the spring and summer variation in the river's freshwater flow, and the effect of certain assumed modes of cannibalism were also included in these analyses. Quantitative estimates of the Ricker parameters alpha and beta representing compensatory reserve and density dependent mortality, respectively, in the system were extracted from these fits. In addition, an approach to modeling the influence of certain density-dependent and density-independent growth factors on the various modes of mortality is presented. All of the above procedures are directed toward estimating the change a given impact may induce on the stock-recruitment model parameters alpha and beta. These changes in alpha and beta are used in various equilibrium reduction models to estimate the percentage change in the equilibrium spawning population that, all other things remaining equal, can be expected in the presence of the impact under study. 15 refs., 3 tabs

  11. Development of the Japanese reference man model for age-specific phantoms

    International Nuclear Information System (INIS)

    Recent interest in improving methods for calculating radiation doses to atomic bomb survivors necessitates reinforcing the data on masses of organs of the Japanese population in 1945, including those that are not calculated by DS02, as well as increasing the number of phantoms for different ages. Reference is made to published data on the masses of organs in normal Japanese subjects of 0-90 y of age with more than 5000 samples during 1970-80, as well as the weight and size of the total body. The first Japanese Reference Man model, primarily based on these data and following the ICRP Reference Man concept, is briefly explained. It provides a set of reference values for males and females of six age groups, i.e. 3 months, 1, 5, 10, 15 and 20-50 y. To consider the organ masses of the Japanese population in 1945, the data during the period 1970-80 are compared with the literature data of normal Japanese reported in 1952. Differences between the two sets of organ data in adults are discussed in relation to changes in the national status of nutrition. Additional organ masses of current interest for the Japanese population in 1945 are preliminarily considered. (author)

  12. Modeling tracers of young stellar population age in star-forming galaxies

    International Nuclear Information System (INIS)

    The young stellar population of a star-forming galaxy is the primary engine driving its radiative properties. As a result, the age of a galaxy's youngest generation of stars is critical for a detailed understanding of its star formation history, stellar content, and evolutionary state. Here we present predicted equivalent widths for the Hβ, Hα, and Brγ recombination lines as a function of stellar population age. The equivalent widths are produced by the latest generations of stellar evolutionary tracks and the Starburst99 stellar population synthesis code, and are the first to fully account for the combined effects of both nebular emission and continuum absorption produced by the synthetic stellar population. Our grid of model stellar populations spans six metallicities (0.001 < Z < 0.04), two treatments of star formation history (a 106 M ☉ instantaneous burst and a continuous star formation rate of 1 M ☉ yr–1), and two different treatments of initial rotation rate (v rot = 0.0v crit and 0.4v crit). We also investigate the effects of varying the initial mass function. Given constraints on galaxy metallicity, our predicted equivalent widths can be applied to observations of star-forming galaxies to approximate the age of their young stellar populations.

  13. C. elegans model identifies genetic modifiers of alpha-synuclein inclusion formation during aging.

    Directory of Open Access Journals (Sweden)

    Tjakko J van Ham

    2008-03-01

    Full Text Available Inclusions in the brain containing alpha-synuclein are the pathological hallmark of Parkinson's disease, but how these inclusions are formed and how this links to disease is poorly understood. We have developed a C. elegans model that makes it possible to monitor, in living animals, the formation of alpha-synuclein inclusions. In worms of old age, inclusions contain aggregated alpha- synuclein, resembling a critical pathological feature. We used genome-wide RNA interference to identify processes involved in inclusion formation, and identified 80 genes that, when knocked down, resulted in a premature increase in the number of inclusions. Quality control and vesicle-trafficking genes expressed in the ER/Golgi complex and vesicular compartments were overrepresented, indicating a specific role for these processes in alpha-synuclein inclusion formation. Suppressors include aging-associated genes, such as sir-2.1/SIRT1 and lagr-1/LASS2. Altogether, our data suggest a link between alpha-synuclein inclusion formation and cellular aging, likely through an endomembrane-related mechanism. The processes and genes identified here present a framework for further study of the disease mechanism and provide candidate susceptibility genes and drug targets for Parkinson's disease and other alpha-synuclein related disorders.

  14. Inflammation and Cell Death in Age-Related Macular Degeneration: An Immunopathological and Ultrastructural Model.

    Science.gov (United States)

    Ardeljan, Christopher P; Ardeljan, Daniel; Abu-Asab, Mones; Chan, Chi-Chao

    2014-01-01

    The etiology of Age-related Macular Degeneration (AMD) remains elusive despite the characterization of many factors contributing to the disease in its late-stage phenotypes. AMD features an immune system in flux, as shown by changes in macrophage polarization with age, expression of cytokines and complement, microglial accumulation with age, etc. These point to an allostatic overload, possibly due to a breakdown in self vs. non-self when endogenous compounds and structures acquire the appearance of non-self over time. The result is inflammation and inflammation-mediated cell death. While it is clear that these processes ultimately result in degeneration of retinal pigment epithelium and photoreceptor, the prevalent type of cell death contributing to the various phenotypes is unknown. Both molecular studies as well as ultrastructural pathology suggest pyroptosis, and perhaps necroptosis, are the predominant mechanisms of cell death at play, with only minimal evidence for apoptosis. Herein, we attempt to reconcile those factors identified by experimental AMD models and integrate these data with pathology observed under the electron microscope-particularly observations of mitochondrial dysfunction, DNA leakage, autophagy, and cell death. PMID:25580276

  15. Self-organized Criticality in an Integrate-and-Fire Neuron Model Based on Modified Aging Networks

    International Nuclear Information System (INIS)

    Based on an integrate-and-fire mechanism, we investigate self-organized criticality of a simple neuron model on a modified BA scale-free network with aging nodes. In our model, we find that the distribution of avalanche size follows power-law behavior. The critical exponent τ depends on the aging exponent α. The structures of the network with aging of nodes change with an increase of α. The different topological structures lead to different behaviors in models of integrate-and-fire neurons.

  16. The Gene Expression Profile of D-galactose Induced Aging Model Rat Using cDNA Microarray

    Institute of Scientific and Technical Information of China (English)

    Li Min(李珉); Wang Gang; Zhang Wei; Wang Miqu; Zhang Yizheng

    2004-01-01

    In order to study the molecular mechanism of D-galactose induced aging model, cDNA microarray is used to analyze gene expression profiles of both normal and D-galactose induced aging model rats. D-galactose induced aging model rats are injected with D-galactose, while normal rats are injected with physiological saline as control. After 7 weeks, the two groups of rats are killed simultaneously. Their livers are harvested for genome-wide expression analysis. D-galactose treated rats showed changes in gene expression associated with increase or decrease in xenobiotic metabolism, protein metabolism and energy metabolism.

  17. Hierarchical Linear Modeling Analyses of NEO-PI-R Scales In the Baltimore Longitudinal Study of Aging

    OpenAIRE

    Terracciano, Antonio; McCrae, Robert R.; Brant, Larry J; Costa, Paul T.

    2005-01-01

    We examined age trends in the five factors and 30 facets assessed by the Revised NEO Personality Inventory in Baltimore Longitudinal Study of Aging data (N = 1,944; 5,027 assessments) collected between 1989 and 2004. Consistent with cross-sectional results, Hierarchical Linear Modeling analyses showed gradual personality changes in adulthood: a decline up to age 80 in Neuroticism, stability and then decline in Extraversion, decline in Openness, increase in Agreeableness, and increase up to ag...

  18. Incorporating harvest rates into the sex-age-kill model for white-tailed deer

    Science.gov (United States)

    Norton, Andrew S.; Diefenbach, Duane R.; Rosenberry, Christopher S.; Wallingford, Bret D.

    2013-01-01

    Although monitoring population trends is an essential component of game species management, wildlife managers rarely have complete counts of abundance. Often, they rely on population models to monitor population trends. As imperfect representations of real-world populations, models must be rigorously evaluated to be applied appropriately. Previous research has evaluated population models for white-tailed deer (Odocoileus virginianus); however, the precision and reliability of these models when tested against empirical measures of variability and bias largely is untested. We were able to statistically evaluate the Pennsylvania sex-age-kill (PASAK) population model using realistic error measured using data from 1,131 radiocollared white-tailed deer in Pennsylvania from 2002 to 2008. We used these data and harvest data (number killed, age-sex structure, etc.) to estimate precision of abundance estimates, identify the most efficient harvest data collection with respect to precision of parameter estimates, and evaluate PASAK model robustness to violation of assumptions. Median coefficient of variation (CV) estimates by Wildlife Management Unit, 13.2% in the most recent year, were slightly above benchmarks recommended for managing game species populations. Doubling reporting rates by hunters or doubling the number of deer checked by personnel in the field reduced median CVs to recommended levels. The PASAK model was robust to errors in estimates for adult male harvest rates but was sensitive to errors in subadult male harvest rates, especially in populations with lower harvest rates. In particular, an error in subadult (1.5-yr-old) male harvest rates resulted in the opposite error in subadult male, adult female, and juvenile population estimates. Also, evidence of a greater harvest probability for subadult female deer when compared with adult (≥2.5-yr-old) female deer resulted in a 9.5% underestimate of the population using the PASAK model. Because obtaining

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

    Science.gov (United States)

    Coggins, L.G., Jr.; Pine, William E., III; 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.

  20. [Current model of breakfast for different age groups: children, a adolescents and adults].

    Science.gov (United States)

    Núñez, C; Cuadrado, C; Carbajal, A; Moreiras, O

    1998-01-01

    The objective of the present work is to assess the current breakfast model in different age groups: children between the ages of 6 and 12 years (n = 54); adolescents between the ages of 13 and 17 years (n = 174); and adults, older than 18 years of age (n = 252). For this a questionnaire has been designed that follows the standards of that used for a similar study by our team in 1984 on a sample of 1350 individuals. The modified and amplified questionnaire included open and closed questions about: the omission of breakfast and its causes, foods that are a part of breakfast, the most frequent types and the variations, the role of the second breakfast, the number of fasting hours since dinner, the time spent of breakfast, and the subjective opinion regarding the importance or not of having breakfast. 98.95% answer yes to the question do you have breakfast, but only 9% eats a nutritionally correct breakfast, one defined as that breakfast that supplies 20% of the total energy and includes foods from at least four different groups. All the children included some form of milk product in their breakfast. The adolescents consumed the lowest proportion of cereals (19.4%) and the highest proportion of pastries (24.2%). The percentage of adults who drink coffee with milk (57%) and sugar (37.7%) is significantly higher than that it the other two groups. Bread (37.7%), pastries (28.3%) and cookies (26.1%) are the solid foods eaten most by the adults. The children spend the longest time on breakfast. 35.9% of the sample varies their breakfast, 43.1% never does, and 21% does so sometimes. The average time elapsed between dinner and breakfast is 10.5 +/- 1.2 hours. It is advisable to have a more nutritionally balanced breakfast, including different foods from at least four groups, and including a greater variety in the menus. PMID:9780752

  1. Age dependence of radiation-induced renal cell carcinomas in an Eker rat model

    International Nuclear Information System (INIS)

    Exposure to carcinogens early in life may contribute to cancer development later in life. The amount of radiation exposure children experience during medical procedures has been increasing, so it is important to evaluate the radiation risk of cancer in developing organs. Toward this goal, we assessed the risk of developing renal cell carcinoma using Eker rats as a kidney tumor model. F1 hybrids of male Eker (Tsc2 mutant) and female F344 rats were irradiated with 0.5 or 2 Gy gamma radiation on gestation days 15 and 19, and on postnatal days 5, 20, and 49. At 27 weeks of age, kidneys were examined for proliferative lesions. Preneoplastic lesions such as phenotypically altered tubules increased after postnatal irradiation as a function of age-at-irradiation, and hyperplasia were greatly increased after perinatal and postnatal irradiation. In contrast, development of adenoma and adenocarcinoma were evident in animals irradiated at perinatal ages, being maximal at gestational day 19. The frequency of loss of heterozygosity (LOH) at the Tsc2 locus was unexpectedly low -0% (0 of 4) for the unirradiated control, and 17% (6 of 35) for the irradiated group. Irrespective of LOH, the mTOR (mammalian target of rapamycin) pathway, which is negatively regulated by the Tsc1/2 complex, was activated in both benign and malignant lesions, as evidenced by phosphorylation of S6 ribosomal protein and 4E-BP1. This suggests that the wild-type Tsc2 allele may be functionally inactivated. In conclusion, actively growing kidneys in perinatal-aged (F344 x Eker) F1 rats (Tsc2+/- are at risk for radiation-induced malignant transformation of the renal epithelium associated with mTOR activation. (author)

  2. Numerical Modeling of the Last Glacial Maximum Yellowstone Ice Cap Captures Asymmetry in Moraine Ages

    Science.gov (United States)

    Anderson, L. S.; Wickert, A. D.; Colgan, W. T.; Anderson, R. S.

    2014-12-01

    The Last Glacial Maximum (LGM) Yellowstone Ice Cap was the largest continuous ice body in the US Rocky Mountains. Terminal moraine ages derived from cosmogenic radionuclide dating (e.g., Licciardi and Pierce, 2008) constrain the timing of maximum Ice Cap extent. Importantly, the moraine ages vary by several thousand years around the Ice Cap; ages on the eastern outlet glaciers are significantly younger than their western counterparts. In order to interpret these observations within the context of LGM climate in North America, we perform two numerical glacier modeling experiments: 1) We model the initiation and growth of the Ice Cap to steady state; and 2) We estimate the range of LGM climate states which led to the formation of the Ice Cap. We use an efficient semi-implicit 2-D glacier model coupled to a fully implicit solution for flexural isostasy, allowing for transient links between climatic forcing, ice thickness, and earth surface deflection. Independent of parameter selection, the Ice Cap initiates in the Absaroka and Beartooth mountains and then advances across the Yellowstone plateau to the west. The Ice Cap advances to its maximum extent first to the older eastern moraines and last to the younger western and northwestern moraines. This suggests that the moraine ages may reflect the timescale required for the Ice Cap to advance across the high elevation Yellowstone plateau rather than the timing of local LGM climate. With no change in annual precipitation from the present, a mean summer temperature drop of 8-9° C is required to form the Ice Cap. Further parameter searches provide the full range of LGM paleoclimate states that led to the Yellowstone Ice Cap. Using our preferred parameter set, we find that the timescale for the growth of the complete Ice Cap is roughly 10,000 years. Isostatic subsidence helps explain the long timescale of Ice Cap growth. The Yellowstone Ice Cap caused a maximum surface deflection of 300 m (using a constant effective elastic

  3. Normal forms for semilinear equations with non-dense domain with applications to age structured models

    Science.gov (United States)

    Liu, Zhihua; Magal, Pierre; Ruan, Shigui

    2014-08-01

    Normal form theory is very important and useful in simplifying the forms of equations restricted on the center manifolds in studying nonlinear dynamical problems. In this paper, using the center manifold theorem associated with the integrated semigroup theory, we develop a normal form theory for semilinear Cauchy problems in which the linear operator is not densely defined and is not a Hille-Yosida operator and present procedures to compute the Taylor expansion and normal form of the reduced system restricted on the center manifold. We then apply the main results and computation procedures to determine the direction of the Hopf bifurcation and stability of the bifurcating periodic solutions in a structured evolutionary epidemiological model of influenza A drift and an age structured population model.

  4. Little Ice Age glaciers in Britain: Glacier–climate modelling in the Cairngorm Mountains

    Energy Technology Data Exchange (ETDEWEB)

    Stephan Harrison; Ann V. Rowan; Neil F. Glasser; Jasper Knight; Mitchell A. Plummer; Stephanie C. Mills

    2014-02-01

    It is widely believed that the last glaciers in the British Isles disappeared at the end of the Younger Dryas stadial (12.9–11.7 cal. kyr BP). Here, we use a glacier–climate model driven by data from local weather stations to show for the first time that glaciers developed during the Little Ice Age (LIA) in the Cairngorm Mountains. Our model is forced from contemporary conditions by a realistic difference in mean annual air temperature of -1.5 degrees C and an increase in annual precipitation of 10%, and confirmed by sensitivity analyses. These results are supported by the presence of small boulder moraines well within Younger Dryas ice limits, and by a dating programme on a moraine in one cirque. As a result, we argue that the last glaciers in the Cairngorm Mountains (and perhaps elsewhere in upland Britain) existed in the LIA within the last few hundred years, rather than during the Younger Dryas.

  5. Optimization of the Heating System Use in Aged Public Buildings via Model Predictive Control

    Directory of Open Access Journals (Sweden)

    Edorta Carrascal

    2016-03-01

    Full Text Available This work presents the implementation of a Model Predictive Control (MPC scheme used to study the improvement of the thermal quality in aged residential buildings without any rehabilitation. The controller manages the heating system of an experimentally characterized model of a residential dwelling in a social block built during the decade of the 1960s located in the neighborhood of Otxarkoaga (Bilbao, Spain, so as to obtain an optimal energy efficiency performance. Due to the characteristics of the construction in those days, this kind of buildings suffer problems related to the use of awkward building materials and inefficient heating systems. A comparison with traditionally used ON-OFF hysteresis control is presented in order to demonstrate the energetic improvement provided by the MPC scheme. Besides, the variation of different parameters of the MPC is also studied to determine its influence over the energy consumption and comfort conditions.

  6. Parameterizing age patterns of demographic rates with the multiexponential model schedule.

    Science.gov (United States)

    Rogers, A; Little, J S

    1994-02-01

    "For nearly 200 years actuaries, statisticians, and demographers have sought to summarize the age pattern of mortality rates by means of a limited number of parameters. Such 'model schedules' have also been useful in representing schedules of rates other than mortality....This paper illustrates a particular general functional form for such model schedules: the multiexponential function. It discusses the changing behavior of this function as its parameters take on different values and examines the quality of the fits of this function to observed data on mortality, fertility, and migration." This is a revised version of a paper originally presented at the 1993 Annual Meeting of the Population Association of America. (SUMMARY IN FRE) PMID:12287088

  7. The Aldous-Shields model revisited (with application to cellular ageing)

    CERN Document Server

    Best, Katharina

    2010-01-01

    In Aldous and Shields (1988), a model for a rooted, growing random binary tree was presented. For some c>0, an external vertex splits at rate c^(-i) (and becomes internal) if its distance from the root (depth) is i. For c>1, we reanalyse the tree profile, i.e. the numbers of external vertices in depth i=1,2,.... Our main result are concrete formulas for the expectation and covariance-structure of the profile. In addition, we present the application of the model to cellular ageing. Here, we assume that nodes in depth h+1 are senescent, i.e. do not split. We obtain a limit result for the proportion of non-senescent vertices for large h.

  8. Holographic Dark Energy Model Characterized by the Conformal-age-like Length

    CERN Document Server

    Huang, Zhuo-Peng

    2012-01-01

    A holographic dark energy model characterized by the conformal-age-like length scale $L= \\frac{1}{a^4(t)}\\int_0^tdt' a^3(t') $ is motivated from the four dimensional spacetime volume at cosmic time $t$ in the flat Friedmann-Robertson-Walker universe. It is shown that when the background constituent with constant equation of state $w_m$ dominates the universe in the early time, the fractional energy density of the dark energy scales as $\\Omega_{de}\\simeq \\frac94(3+w_m)^2d^2a^2$ with the equation of state given by $w_{de}\\simeq-\\frac23 +w_m$. The value of $w_m$ is taken to be $w_m\\simeq-1$ during inflation, $w_m=\\frac13$ in radiation-dominated epoch and $w_m=0$ in matter-dominated epoch respectively. When the model parameter $d$ takes the normal value at order one, the fractional density of dark energy is naturally negligible in the early universe, $\\Omega_{de} \\ll 1$ at $a \\ll 1$. With such an analytic feature, the model can be regarded as a single-parameter model like the $\\Lambda$CDM model, so that the prese...

  9. Infant Gaze Following and Pointing Predict Accelerated Vocabulary Growth through Two Years of Age: A Longitudinal, Growth Curve Modeling Study

    Science.gov (United States)

    Brooks, Rechele; Meltzoff, Andrew N.

    2008-01-01

    We found that infant gaze following and pointing predicts subsequent language development. At ages 0 ; 10 or 0 ; 11, infants saw an adult turn to look at an object in an experimental setting. Productive vocabulary was assessed longitudinally through two years of age. Growth curve modeling showed that infants who gaze followed and looked longer at…

  10. Diagnosis of hepatic fibrosis in hepatitis B patients by logistic regression modeling based on plasma amino acid ratio and age

    Institute of Scientific and Technical Information of China (English)

    张占卿

    2013-01-01

    Objective To explore the efficacy of logistic regression modeling based on plasma amino acid profile and patient age,for diagnosing hepatic fibrosis in patients with chronic hepatitis B (CHB) .Methods One-hundredand-forty-eight patients (108 males;mean age:38.1±11.9 years,range:16—72 years) histologically

  11. Effects of extrinsic mortality on the evolution of aging: a stochastic modeling approach.

    Directory of Open Access Journals (Sweden)

    Maxim Nikolaievich Shokhirev

    Full Text Available The evolutionary theories of aging are useful for gaining insights into the complex mechanisms underlying senescence. Classical theories argue that high levels of extrinsic mortality should select for the evolution of shorter lifespans and earlier peak fertility. Non-classical theories, in contrast, posit that an increase in extrinsic mortality could select for the evolution of longer lifespans. Although numerous studies support the classical paradigm, recent data challenge classical predictions, finding that high extrinsic mortality can select for the evolution of longer lifespans. To further elucidate the role of extrinsic mortality in the evolution of aging, we implemented a stochastic, agent-based, computational model. We used a simulated annealing optimization approach to predict which model parameters predispose populations to evolve longer or shorter lifespans in response to increased levels of predation. We report that longer lifespans evolved in the presence of rising predation if the cost of mating is relatively high and if energy is available in excess. Conversely, we found that dramatically shorter lifespans evolved when mating costs were relatively low and food was relatively scarce. We also analyzed the effects of increased predation on various parameters related to density dependence and energy allocation. Longer and shorter lifespans were accompanied by increased and decreased investments of energy into somatic maintenance, respectively. Similarly, earlier and later maturation ages were accompanied by increased and decreased energetic investments into early fecundity, respectively. Higher predation significantly decreased the total population size, enlarged the shared resource pool, and redistributed energy reserves for mature individuals. These results both corroborate and refine classical predictions, demonstrating a population-level trade-off between longevity and fecundity and identifying conditions that produce both

  12. Crust evolution in Southeast China:evidence from Nd model ages of granitoids

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Nd isotopic compositions of 58 granitoids in South China have been reported in this paper.These data together with other published data reveal that granites with Nd model ages (tDM) greater than 1.8 Ga are distributed mainly in three areas:southwestern Zhejiang-northwestern Fujian,two sides of the Wuyi Mountain and Wanyangshan-Zhuguangshan.These granites are believed to be derived from partial melting of old crust in these areas.The Mesozoic granites with tDM<1.6 Ga are distributed in three zones:the Gangang structural zone,Nanling latitudinal structural zone and Fujian-Zhejiang coastal zone.These zones may have been an extensional tectonic setting and mantle-derived components or magmas may have been involved to different extents in the granite formation.Based on Nd model ages of granites and published chronological data of mafic and ultramafic rocks,it is believed that the crust in South China experienced episodic accretions,among which the early-middle Proterozoic is the most important period of crustal accretion.

  13. Crust evolution in Southeast China: evidence from Nd model ages of granitoids

    Institute of Scientific and Technical Information of China (English)

    沈渭洲; 凌洪飞; 李武显; 王德滋

    2000-01-01

    Nd isotopic compositions of 58 granitoids in South China have been reported in this paper; These data together with other published data reveal that granites with Nd model ages (tDM) greater than 1.8 Ga are distributed mainly in three areas: southwestern Zhejiang-northwestern Fujian, two sides of the Wuyi Mountain and Wanyangshan-Zhuguangshan. These granites are believed to be derived from partial melting of old crust in these areas. The Mesozoic granites with (DM < 1.6 Ga are distributed in three zones: the Gangang structural zone, Nanling latitudinal structural zone and Fujian-Zhejiang coastal zone. These zones may have been an extensional tectonic setting and mantle-derived components or magmas may have been involved to different extents in the granite formation. Based on Nd model ages of granites and published chronological data of mafic and ultramafic rocks, it is believed that the crust in South China experienced episodic accretions, among which the early-middle Proterozoic is the most important p

  14. A Model-based Prognostics Methodology for Electrolytic Capacitors Based on Electrical Overstress Accelerated Aging

    Science.gov (United States)

    Celaya, Jose; Kulkarni, Chetan; Biswas, Gautam; Saha, Sankalita; Goebel, Kai

    2011-01-01

    A remaining useful life prediction methodology for electrolytic capacitors is presented. This methodology is based on the Kalman filter framework and an empirical degradation model. Electrolytic capacitors are used in several applications ranging from power supplies on critical avionics equipment to power drivers for electro-mechanical actuators. These devices are known for their comparatively low reliability and given their criticality in electronics subsystems they are a good candidate for component level prognostics and health management. Prognostics provides a way to assess remaining useful life of a capacitor based on its current state of health and its anticipated future usage and operational conditions. We present here also, experimental results of an accelerated aging test under electrical stresses. The data obtained in this test form the basis for a remaining life prediction algorithm where a model of the degradation process is suggested. This preliminary remaining life prediction algorithm serves as a demonstration of how prognostics methodologies could be used for electrolytic capacitors. In addition, the use degradation progression data from accelerated aging, provides an avenue for validation of applications of the Kalman filter based prognostics methods typically used for remaining useful life predictions in other applications.

  15. Modelling antecedents of blood donation motivation among non-donors of varying age and education.

    Science.gov (United States)

    Lemmens, K P H; Abraham, C; Ruiter, R A C; Veldhuizen, I J T; Dehing, C J G; Bos, A E R; Schaalma, H P

    2009-02-01

    Understanding blood donation motivation among non-donors is prerequisite to effective recruitment. Two studies explored the psychological antecedents of blood donation motivation and the generalisability of a model of donation motivation across groups differing in age and educational level. An older well-educated population and a younger less well-educated population were sampled. The studies assessed the role of altruism, fear of blood/needles and donation-specific cognitions including attitudes and normative beliefs derived from an extended theory of planned behaviour (TPB). Across both samples, results showed that affective attitude, subjective norm, descriptive norm, and moral norm were the most important correlates of blood donation intentions. Self-efficacy was more important among the younger less well-educated group. Altruism was related to donation motivation but only indirectly through moral norm. Similarly, fear of blood/needles only had an indirect effect on motivation through affective attitude and self-efficacy. Additional analyses with the combined data set found no age or education moderation effects, suggesting that this core model of donation-specific cognitions can be used to inform future practical interventions recruiting new blood donors in the general population. PMID:18547458

  16. Adverse Geriatric Outcomes Secondary to Polypharmacy in a Mouse Model: The Influence of Aging.

    Science.gov (United States)

    Huizer-Pajkos, Aniko; Kane, Alice E; Howlett, Susan E; Mach, John; Mitchell, Sarah J; de Cabo, Rafael; Le Couteur, David G; Hilmer, Sarah N

    2016-05-01

    We aimed to develop a mouse model of polypharmacy, primarily to establish whether short-term exposure to polypharmacy causes adverse geriatric outcomes. We also investigated whether old age increased susceptibility to any adverse geriatric outcomes of polypharmacy. Young (n= 10) and old (n= 21) male C57BL/6 mice were administered control diet or polypharmacy diet containing therapeutic doses of five commonly used medicines (simvastatin, metoprolol, omeprazole, acetaminophen, and citalopram). Mice were assessed before and after the 2- to 4-week intervention. Over the intervention period, we observed no mortality and no change in food intake, body weight, or serum biochemistry in any age or treatment group. In old mice, polypharmacy caused significant declines in locomotor activity (pre minus postintervention values in control 2 ± 13 counts, polypharmacy 32 ± 7 counts,p< .05) and front paw wire holding impulse (control -2.45 ± 1.02 N s, polypharmacy +1.99 ± 1.19 N s,p< .05), loss of improvement in rotarod latency (control -59 ± 11 s, polypharmacy -1.7 ± 17 s,p< .05), and lowered blood pressure (control -0.2 ± 3 mmHg, polypharmacy 11 ± 4 mmHg,p< .05). In young mice, changes in outcomes over the intervention period did not differ between control and polypharmacy groups. This novel model of polypharmacy is feasible. Even short-term polypharmacy impairs mobility, balance, and strength in old male mice. PMID:25940962

  17. Removing the age restrictions for rotavirus vaccination: a benefit-risk modeling analysis.

    Directory of Open Access Journals (Sweden)

    Manish M Patel

    Full Text Available BACKGROUND: To minimize potential risk of intussusception, the World Health Organization (WHO recommended in 2009 that rotavirus immunization should be initiated by age 15 weeks and completed before 32 weeks. These restrictions could adversely impact vaccination coverage and thereby its health impact, particularly in developing countries where delays in vaccination often occur. METHODS AND FINDINGS: We conducted a modeling study to estimate the number of rotavirus deaths prevented and the number of intussusception deaths caused by vaccination when administered on the restricted schedule versus an unrestricted schedule whereby rotavirus vaccine would be administered with DTP vaccine up to age 3 years. Countries were grouped on the basis of child mortality rates, using WHO data. Inputs were estimates of WHO rotavirus mortality by week of age from a recent study, intussusception mortality based on a literature review, predicted vaccination rates by week of age from USAID Demographic and Health Surveys, the United Nations Children's Fund (UNICEF Multiple Indicator Cluster Surveys (MICS, and WHO-UNICEF 2010 country-specific coverage estimates, and published estimates of vaccine efficacy and vaccine-associated intussusception risk. On the basis of the error estimates and distributions for model inputs, we conducted 2,000 simulations to obtain median estimates of deaths averted and caused as well as the uncertainty ranges, defined as the 5th-95th percentile, to provide an indication of the uncertainty in the estimates. We estimated that in low and low-middle income countries a restricted schedule would prevent 155,800 rotavirus deaths (5th-95th centiles, 83,300-217,700 while causing potentially 253 intussusception deaths (76-689. In contrast, vaccination without age restrictions would prevent 203,000 rotavirus deaths (102,000-281,500 while potentially causing 547 intussusception deaths (237-1,160. Thus, removing the age restrictions would avert an

  18. Calendar ageing analysis of a LiFePO4/graphite cell with dynamic model validations: Towards realistic lifetime predictions

    Science.gov (United States)

    Sarasketa-Zabala, E.; Gandiaga, I.; Rodriguez-Martinez, L. M.; Villarreal, I.

    2014-12-01

    The present study aims at establishing a methodology for a comprehensive calendar ageing predictive model development, focusing specially on validation procedures. A LFP-based Li-ion cell performance degradation was analysed under different temperature and SOC storage conditions. Five static calendar ageing conditions were used for understanding the ageing trends and modelling the dominant ageing phenomena (SEI growth and the resulting loss of active lithium). The validation process included an additional test under other constant operating conditions (static validation) and other four tests under non-constant impact factors operating schemes within the same experiment (dynamic validation), in response to battery stress conditions in real applications. Model predictions are in good agreement with experimental results as the residuals are always below 1% for experiments run for 300-650 days. The model is able to predict dynamic behaviour close to real operating conditions and the level of accuracy corresponds to a root-mean-square error of 0.93%.

  19. The Changing Nature of Adult Education in the Age of Transnational Migration: Toward a Model of Recognitive Adult Education

    Science.gov (United States)

    Guo, Shibao

    2015-01-01

    This chapter examines the changing nature of adult education in the age of transnational migration and proposes recognitive adult education as an inclusive model that acknowledges and affirms cultural difference and diversity as positive and desirable assets.

  20. Testing the accuracy of a Bayesian central-dose model for single-grain OSL, using known-age samples

    DEFF Research Database (Denmark)

    Guerin, Guillaume; Combès, Benoit; Lahaye, Christelle; Thomsen, Kristina Jørkov; Tribolo, Chantal; Urbanova, Petra; Guibert, Pierre; Mercier, Norbert; Valladas, Hélène

    2015-01-01

    on multi-grain OSL age estimates, these samples are presumed to have been both well-bleached at burial, and unaffected by mixing after deposition. Two ways of estimating single-grain ages are then compared: the standard approach on the one hand, consisting of applying the Central Age Model to De...... overdispersion parameter for well-bleached samples; (ii) dose recovery experiments do not seem to be a very reliable tool to estimate the accuracy of a SAR measurement protocol for age determination....

  1. A variable age of onset segregation model for linkage analysis, with correction for ascertainment, applied to glioma

    DEFF Research Database (Denmark)

    Sun, Xiangqing; Vengoechea, Jaime; Elston, Robert;

    2012-01-01

    We propose a 2-step model-based approach, with correction for ascertainment, to linkage analysis of a binary trait with variable age of onset and apply it to a set of multiplex pedigrees segregating for adult glioma.......We propose a 2-step model-based approach, with correction for ascertainment, to linkage analysis of a binary trait with variable age of onset and apply it to a set of multiplex pedigrees segregating for adult glioma....

  2. Prediction of residual stress due to early age behaviour of massive concrete structures: on site experiments and macroscopic modelling

    OpenAIRE

    Zreiki, Jihad; Lamour, Vincent; Chaouche, Mohend; Moranville, Micheline

    2008-01-01

    Early age behaviour of concrete is based on complex multi-physical and multiscale phenomena. The predication of both cracking risk and residual stresses in hardened concrete structures is still a challenging task. We propose in this paper a practical method to characterize in the construction site the material parameters and to identify a macroscopic model from simple tests. We propose for instance to use a restrained shrinkage ring test to identify a basic early age creep model based on a si...

  3. Research progression of aging animal model%衰老动物模型的研究进展

    Institute of Scientific and Technical Information of China (English)

    王喆; 李瑞生

    2013-01-01

    衰老动物模型分为自发性动物模型、诱发性动物模型和转基因动物模型.采用自然衰老动物或者是人为因素致衰老的动物为模型是人类研究衰老过程的有效手段,结合各类实验动物的自身特点以及生理特性,建立与临床衰老症状相似的动物模型,已成为探索人类衰老机制,并寻找预防和治疗衰老的新方法.%Aging animal models are divided into spontaneous animal models,induced animal models and transgenic animal models. It is an effective means to research human aging process by using natural aging animal or anthropogenic aging animal as a model. According to feature and physiological characteristics of different experimental animals, building this kind of model which is similar to the clinical symptoms has become a new method to explore aging mechanisms,prevent and treat human aging.

  4. A holistic aging model for Li(NiMnCo)O2 based 18650 lithium-ion batteries

    Science.gov (United States)

    Schmalstieg, Johannes; Käbitz, Stefan; Ecker, Madeleine; Sauer, Dirk Uwe

    2014-07-01

    Knowledge on lithium-ion battery aging and lifetime estimation is a fundamental aspect for successful market introduction in high-priced goods like electric mobility. This paper illustrates the parameterization of a holistic aging model from accelerated aging tests. More than 60 cells of the same type are tested to analyze different impact factors. In calendar aging tests three temperatures and various SOC are applied to the batteries. For cycle aging tests especially different cycle depths and mean SOC are taken into account. Capacity loss and resistance increase are monitored as functions of time and charge throughput during the tests. From these data physical based functions are obtained, giving a mathematical description of aging. To calculate the stress factors like temperature or voltage, an impedance based electric-thermal model is coupled to the aging model. The model accepts power and current profiles as input, furthermore an ambient air temperature profile can be applied. Various drive cycles and battery management strategies can be tested and optimized using the lifetime prognosis of this tool. With the validation based on different realistic driving profiles and temperatures, a robust foundation is provided.

  5. Modelling the ageing behaviour of supercapacitors using electrochemical impedance spectroscopy for dynamic applications

    OpenAIRE

    Mohammad Naim, Nur Nafisah

    2015-01-01

    Diagnosis of ageing mechanisms in supercapacitors is made difficult by the enforcement of various ageing factors in the current ageing tests. The thesis presents the exact determination of the ageing mechanism by separating the impacts of high temperature, current cycling and constant voltage applications in accelerated ageing tests. The state of health (SOH) of the supercapacitors are monitored periodically with electrochemical impedance spectroscopy, cyclic voltammetry and constant current ...

  6. Lung cancer susceptibility model based on age, family history and genetic variants.

    Directory of Open Access Journals (Sweden)

    Robert P Young

    Full Text Available BACKGROUND: Epidemiological and pedigree studies suggest that lung cancer results from the combined effects of age, smoking, impaired lung function and genetic factors. In a case control association study of healthy smokers and lung cancer cases, we identified genetic markers associated with either susceptibility or protection to lung cancer. METHODOLOGY/PRINCIPAL FINDINGS: We screened 157 candidate single nucleotide polymorphisms (SNP in a discovery cohort of 439 subjects (200 controls and 239 lung cancer cases and identified 30 SNPs associated with either the healthy smokers (protective or lung cancer (susceptibility phenotype. After genotyping this 30 SNP panel in a validation cohort of 491 subjects (248 controls and 207 lung cancers and, using the same protective and susceptibility genotypes from our discovery cohort, a 20 SNP panel was selected based on replication of SNP associations in the validation cohort. Following multivariate logistic regression analyses, including the selected SNPs from runs 1 and 2, we found age and family history of lung cancer to be significantly and independently associated with lung cancer. Numeric scores were assigned to both the SNP and demographic data, and combined to form a simple algorithm of risk. CONCLUSIONS/SIGNIFICANCE: Significant differences in the distribution of the lung cancer susceptibility score was found between normal controls and lung cancer cases, which remained after accounting for differences in lung function. Validation in other case-control and prospective cohorts are underway to further define the potential clinical utility of this model.

  7. Efficacy of enzyme replacement therapy in an aggravated mouse model of metachromatic leukodystrophy declines with age.

    Science.gov (United States)

    Matthes, Frank; Stroobants, Stijn; Gerlach, Debora; Wohlenberg, Claudia; Wessig, Carsten; Fogh, Jens; Gieselmann, Volkmar; Eckhardt, Matthias; D'Hooge, Rudi; Matzner, Ulrich

    2012-06-01

    Metachromatic leukodystrophy (MLD) is a lysosomal storage disease caused by a functional deficiency of arylsulfatase A (ASA). Previous studies in ASA-knockout mice suggested enzyme replacement therapy (ERT) to be a promising treatment option. The mild phenotype of ASA-knockout mice did, however, not allow to examine therapeutic responses of the severe neurological symptoms that dominate MLD. We, therefore, generated an aggravated MLD mouse model displaying progressive demyelination and reduced nerve conduction velocity (NCV) and treated it by weekly intravenous injections of 20 mg/kg recombinant human ASA for 16 weeks. To analyze the stage-dependent therapeutic effects, ERT was initiated in a presymptomatic, early and progressed disease stage, at age 4, 8 and 12 months, respectively. Brain sulfatide storage, NCV and behavioral alterations were improved only in early, but not in late, treated mice showing a clear age-dependent efficacy of treatment. Hematopoietic stem cell transplantation (HSCT) for late-onset variants is the only therapeutic option for MLD to date. ERT resembles a part of the HSCT rationale, which is based on ASA supply by donor cells. Beyond ERT, our results, therefore, corroborate the clinical observation that HSCT is only effective when performed in early stages of disease. PMID:22388935

  8. Moringa oleifera Mitigates Memory Impairment and Neurodegeneration in Animal Model of Age-Related Dementia

    Directory of Open Access Journals (Sweden)

    Chatchada Sutalangka

    2013-01-01

    Full Text Available To date, the preventive strategy against dementia is still essential due to the rapid growth of its prevalence and the limited therapeutic efficacy. Based on the crucial role of oxidative stress in age-related dementia and the antioxidant and nootropic activities of Moringa oleifera, the enhancement of spatial memory and neuroprotection of M. oleifera leaves extract in animal model of age-related dementia was determined. The possible underlying mechanism was also investigated. Male Wistar rats, weighing 180–220 g, were orally given M. oleifera leaves extract at doses of 100, 200, and 400 mg/kg at a period of 7 days before and 7 days after the intracerebroventricular administration of AF64A bilaterally. Then, they were assessed memory, neuron density, MDA level, and the activities of SOD, CAT, GSH-Px, and AChE in hippocampus. The results showed that the extract improved spatial memory and neurodegeneration in CA1, CA2, CA3, and dentate gyrus of hippocampus together with the decreased MDA level and AChE activity but increased SOD and CAT activities. Therefore, our data suggest that M. oleifera leaves extract is the potential cognitive enhancer and neuroprotectant. The possible mechanism might occur partly via the decreased oxidative stress and the enhanced cholinergic function. However, further explorations concerning active ingredient(s are still required.

  9. Longitudinal examination of the exercise and self-esteem model in middle-aged women.

    Science.gov (United States)

    Elavsky, Steriani

    2010-12-01

    This 2-year prospective study examined the exercise and self-esteem model in middle-aged women (N = 143) previously enrolled in a randomized controlled exercise trial. Across the 2-year period, increases in physical activity (PA) and self-efficacy and reductions in body mass index (BMI) were associated with improved subdomain self-perceptions relative to physical condition, and reductions in BMI were associated with improved subdomain self-perceptions relative to physical condition and body attractiveness. The effects of PA, self-efficacy, and BMI on changes in physical self-worth and global self-esteem were mediated by changes in self-perceptions relative to physical condition and body attractiveness. The results of this longitudinal analysis support the hierarchical and multidimensional structure of self-esteem and indicate that middle-aged women can enhance how they perceive their condition and body attractiveness by continued participation in physical activity, increasing their self-efficacy, and maintaining healthy BMI levels. PMID:21282842

  10. Channel selection in e-commerce age: A strategic analysis of co-op advertising models

    Directory of Open Access Journals (Sweden)

    Yongmei Liu

    2013-03-01

    , such as service and price. We can do some researches from the point of these factors. Third, how demand uncertainty affects the channel selection and co-op advertising strategy is another interesting research item.Practical implications: The manufacturer and the retailer know that the impact of co-op adverting on the demands of traditional channel and direct channel, both would like to choose reasonable strategies to improve the channel coordination. Therefore, it would be best if business managers conduct market survey before they start their co-op advertising campaign.Originality/value: Two new co-op advertising models in E-commerce age are developed, and the impact of product web-fit on these optimal strategies are analyzed and illustrate by some numeral examples. In addition, optimal channel structure in E-commerce age are selected for manufacturer and the retailer.

  11. A multimutation model for cancer based on age-time patterns of radiation effects. 1. Mathematical and epidemiological aspects

    International Nuclear Information System (INIS)

    An idealized mathematical model for carcinogenesis is proposed, based on age-time patterns of excess solid cancer risk seen in the Radiation Effects Research Foundation data on A-bomb survivors. The primary component is similar to the Armitage-Doll multistage model, with the interpretation that the events in that model are somatic mutations. The manner of extending this model to incorporate effects of a specific carcinogen, here an acute irradiation, is novel in the sense that the irradiation can cause any one of the mutations in the multi-event process. The motivation for this formulation is the observation that the excess solid cancer rate associated with radiation exposure appears largely to depend only on attained age, rather than on age at exposure and time since exposure. The model is fitted to the A-bomb survivor data on a class of cancers consisting of the major non-sex-specific types. (author)

  12. Application Server Aging Model and Multi-Level Rejuvenation Strategy Using Semi-Markov Process

    Institute of Scientific and Technical Information of China (English)

    ZHAO Tianhai; QI Yong; SHEN Junyi; HOU Di; ZHENG Xiaomei; LIU Liang

    2006-01-01

    Aiming at the characteristic of the dependency between the application components and the application server platform, a rejuvenation strategy with two different levels of rejuvenation granularities is put forward in this paper including the application component rejuvenation and the application server system rejuvenation. The availability and maintenance cost functions are obtained by means of establishing the application server aging model and the boundary condition of the optimal rejuvenation time is analyzed. Theory analysis indicates that the two-level rejuvenation strategy is superior to the traditional single level one. Finally, evaluation experiments are carried out and numerical result shows that compared with the traditional rejuvenation policy, the rejuvenation strategy proposed in this paper can further increase availability of the application server and reduce maintenance cost.

  13. A spatial age-structured model for describing sea lamprey (Petromyzon marinus) population dynamics

    Science.gov (United States)

    Robinson, Jason M.; Wilberg, Michael J.; Adams, Jean V.; Jones, Michael L.

    2013-01-01

    The control of invasive sea lampreys (Petromyzon marinus) presents large scale management challenges in the Laurentian Great Lakes. No modeling approach has been developed that describes spatial dynamics of lamprey populations. We developed and validated a spatial and age-structured model and applied it to a sea lamprey population in a large river in the Great Lakes basin. We considered 75 discrete spatial areas, included a stock-recruitment function, spatial recruitment patterns, natural mortality, chemical treatment mortality, and larval metamorphosis. Recruitment was variable, and an upstream shift in recruitment location was observed over time. From 1993–2011 recruitment, larval abundance, and the abundance of metamorphosing individuals decreased by 80, 84, and 86%, respectively. The model successfully identified areas of high larval abundance and showed that areas of low larval density contribute significantly to the population. Estimated treatment mortality was less than expected but had a large population-level impact. The results and general approach of this work have applications for sea lamprey control throughout the Great Lakes and for the restoration and conservation of native lamprey species globally.

  14. Modelling the chemically aged and mixed aerosols over the eastern central Atlantic Ocean – potential impacts

    Directory of Open Access Journals (Sweden)

    M. Astitha

    2010-07-01

    Full Text Available Detailed information on the chemical and physical properties of aerosols is important for assessing their role in air quality and climate. This work explores the origin and fate of continental aerosols transported over the Central Atlantic Ocean, in terms of chemical composition, number and size distribution, using chemistry-transport models, satellite data and in situ measurements. We focus on August 2005, a period with intense hurricane and tropical storm activity over the Atlantic Ocean. A mixture of anthropogenic (sulphates, nitrates, natural (desert dust, sea salt and chemically aged (sulphate and nitrate on dust aerosols is found entering the hurricane genesis region, most likely interacting with clouds in the area. Results from our modelling study suggest rather small amounts of accumulation mode desert dust, sea salt and chemically aged dust aerosols in this Atlantic Ocean region. Aerosols of smaller size (Aitken mode are more abundant in the area and in some occasions sulphates of anthropogenic origin and desert dust are of the same magnitude in terms of number concentrations. Typical aerosol number concentrations are derived for the vertical layers near shallow cloud formation regimes, indicating that the aerosol number concentration can reach several thousand particles per cubic centimetre. The vertical distribution of the aerosols shows that the desert dust particles are often transported near the top of the marine cloud layer as they enter into the region where deep convection is initiated. The anthropogenic sulphate aerosol can be transported within a thick layer and enter the cloud deck through multiple ways (from the top, the base of the cloud, and by entrainment. The sodium (sea salt related aerosol is mostly found below the cloud base. The results of this work may provide insights relevant for studies that consider aerosol influences on cloud processes and storm development in the Central Atlantic region.

  15. An investigation of the astronomical theory of the ice ages using a simple climate-ice sheet model

    Science.gov (United States)

    Pollard, D.

    1978-01-01

    The astronomical theory of the Quaternary ice ages is incorporated into a simple climate model for global weather; important features of the model include the albedo feedback, topography and dynamics of the ice sheets. For various parameterizations of the orbital elements, the model yields realistic assessments of the northern ice sheet. Lack of a land-sea heat capacity contrast represents one of the chief difficulties of the model.

  16. Uranium isotopes and dissolved organic carbon in loess permafrost: Modeling the age of ancient ice

    Science.gov (United States)

    Ewing, Stephanie A.; Paces, James B.; O'Donnell, J.A.; Jorgenson, M.T.; Kanevskiy, M.Z.; Aiken, George R.; Shur, Y.; Harden, Jennifer W.; Striegl, Rob

    2015-01-01

    The residence time of ice in permafrost is an indicator of past climate history, and of the resilience and vulnerability of high-latitude ecosystems to global change. Development of geochemical indicators of ground-ice residence times in permafrost will advance understanding of the circumstances and evidence of permafrost formation, preservation, and thaw in response to climate warming and other disturbance. We used uranium isotopes to evaluate the residence time of segregated ground ice from ice-rich loess permafrost cores in central Alaska. Activity ratios of 234U vs. 238U (234U/238U) in water from thawed core sections ranged between 1.163 and 1.904 due to contact of ice and associated liquid water with mineral surfaces over time. Measured (234U/238U) values in ground ice showed an overall increase with depth in a series of five neighboring cores up to 21 m deep. This is consistent with increasing residence time of ice with depth as a result of accumulation of loess over time, as well as characteristic ice morphologies, high segregated ice content, and wedge ice, all of which support an interpretation of syngenetic permafrost formation associated with loess deposition. At the same time, stratigraphic evidence indicates some past sediment redistribution and possibly shallow thaw among cores, with local mixing of aged thaw waters. Using measures of surface area and a leaching experiment to determine U distribution, a geometric model of (234U/238U) evolution suggests mean ages of up to ∼200 ky BP in the deepest core, with estimated uncertainties of up to an order of magnitude. Evidence of secondary coatings on loess grains with elevated (234U/238U) values and U concentrations suggests that refinement of the geometric model to account for weathering processes is needed to reduce uncertainty. We suggest that in this area of deep ice-rich loess permafrost, ice bodies have been preserved from the last glacial period (10–100 ky BP), despite subsequent

  17. Modelling of leaching and geochemical processes in an aged MSWIBA subbase layer

    Energy Technology Data Exchange (ETDEWEB)

    Bendz, David; Suer, Pascal; Sloot, Hans van der; Kosson, David; Flyhammar, Peter

    2009-07-15

    In a previous project, the accumulated effects of leaching and aging in a subbase layer of bottom ash in a test road were investigated. The test road were constructed in 1987 in Linkoeping, Sweden, and was in use until the start of the Vaendoera Q4-241 study in September 2003. The overall objective of the present study is to bring the evaluation of the previous project (Q4-241) further by taking advantage of the existing data, perform complementary laboratory experiments on four composite samples reflecting different degree of exposure to atmosphere and leaching. The specific objectives were to investigate: (i) what processes and mineral phases that govern leaching of macro- and trace elements and DOC in the bottom ash after 16 years (1987- 2003) of aging under field conditions. (ii) how the hydrologic conditions, infiltration of water and leachate production has evolved with time. The following tests were performed on the composite samples: pH-stat test, column test, Fe/Al oxide extraction and TOC fractioning. Geochemical and hydrological modelling where performed with LeachXS/Orchestra and Hydrus 2-D. Daily precipitation data from the Swedish Meteorological and Hydrological Institute (SMHI) from the Malmslaett (Linkoeping) measurement station was used in the hydrological modelling of January 1988 to the 1st of september 2003. The hydraulic modeling results show that the bottom ash subbase layer endure seasonal wet and dry cycles. The results confirm that, depending on the boundary conditions along the shoulders the capillary potential may drive moisture either in or out of the road body. The water retention parameters for bottom ash were crucial in the hydraulic modeling and the capillary forces in bottom ash were found to be significant with a water retention curve close to silt. This explains the observed depletion of easily soluble salts in the test road. The results showed that the accumulated LS ratio for the bottom ash subbase layer reached about LS:10 in

  18. A model for damage load and its implications for the evolution of bacterial aging.

    Directory of Open Access Journals (Sweden)

    Lin Chao

    2010-08-01

    Full Text Available Deleterious mutations appearing in a population increase in frequency until stopped by natural selection. The ensuing equilibrium creates a stable frequency of deleterious mutations or the mutational load. Here I develop the comparable concept of a damage load, which is caused by harmful non-heritable changes to the phenotype. A damage load also ensues when the increase of damage is opposed by selection. The presence of a damage load favors the evolution of asymmetrical transmission of damage by a mother to her daughters. The asymmetry is beneficial because it increases fitness variance, but it also leads to aging or senescence. A mathematical model based on microbes reveals that a cell lineage dividing symmetrically is immortal if lifetime damage rates do not exceed a threshold. The evolution of asymmetry allows the lineage to persist above the threshold, but the lineage becomes mortal. In microbes with low genomic mutation rates, it is likely that the damage load is much greater than the mutational load. In metazoans with higher genomic mutation rates, the damage and the mutational load could be of the same magnitude. A fit of the model to experimental data shows that Escherichia coli cells experience a damage rate that is below the threshold and are immortal under the conditions examined. The model estimates the asymmetry level of E. coli to be low but sufficient for persisting at higher damage rates. The model also predicts that increasing asymmetry results in diminishing fitness returns, which may explain why the bacterium has not evolved higher asymmetry.

  19. Application of artificial neural networks for modelling correlations in age hardenable aluminium alloys

    Directory of Open Access Journals (Sweden)

    F. Musharavati

    2010-07-01

    Full Text Available Purpose: This paper discusses some of the preliminary results of an ongoing research on the applications of artificial neural networks (ANNs in modelling, predicting and simulating correlations between mechanical properties of age hardenable aluminium alloys as a function of alloy composition.Design/methodology/approach: Appropriate combinations of inputs and outputs were selected for neural network modelling. Multilayer feedforward networks were created and trained using datasets from public literature. Influences of alloying elements, alloy composition and processing parameters on mechanical properties of aluminium alloys were predicted and simulated using ANNs models.Two sample t-tests were used to analyze the prediction accuracy of the trained ANNs.Findings: Good performances of the neural network models were achieved. The models were able to predict mechanical properties within acceptable margins of error and were able to provide relevant simulated data for correlating alloy composition and processing parameters with mechanical properties. Therefore, ANNs models are convenient and powerful tools that can provide useful information which can be used to identify desired properties in new aluminium alloys for practical applications in new and/or improved aluminium products.Research limitations/implications: Few public data bases are available for modelling properties. Minor contradictions on the experimental values of properties and alloy compositions were also observed. Future work will include further development of simulated data into property charts.Practical implications: Correlations between mechanical properties and alloy compositions can help in identifying a suitable alloy for a new or improved aluminum product application. In addition, availability of simulated structure-process-property data or charts assists in reducing the time and costs of trial and error experimental approaches by providing near-optimal values that can be used

  20. Aged Garlic Extract Attenuates Neuronal Injury in a Rat Model of Spinal Cord Ischemia/Reperfusion Injury.

    Science.gov (United States)

    Cemil, Berker; Gokce, Emre Cemal; Kahveci, Ramazan; Gokce, Aysun; Aksoy, Nurkan; Sargon, Mustafa Fevzi; Erdogan, Bulent; Kosem, Bahadir

    2016-06-01

    Garlic has been used as a food as well as a component of traditional medicine. Aged garlic extract (AGE) is claimed to promote human health through antioxidant/anti-inflammatory activities with neuroprotective effects. We evaluated the possible beneficial effect of AGE neurologically, pathologically, ultrastructurally, and biochemically in a spinal cord ischemia-reperfusion (I/R) model of rats. Twenty-four Sprague-Dawley rats were divided into three groups: sham (no I/R), I/R, and AGE (I/R+AGE); each group consisted of eight animals. Animals were evaluated neurologically with the Basso, Beattie, and Bresnahan (BBB) scoring system. The spinal cord tissue samples were harvested for pathological and ultrastructural examinations. Oxidative products (Malondialdehyde, nitric oxide), antioxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase), inflammatory cytokines (tissue tumor necrosis factor alpha, interleukin-1), and caspase-3 activity were analyzed. The AGE group had significantly higher BBB scores than the I/R group. Pathologically, AGE group revealed reduced degree of ischemia and spinal cord edema. Ultrastructural results also showed preservation of tissue structure in the AGE group. Oxidative product levels of the I/R group were significantly higher than both the other groups, and antioxidant enzyme levels of AGE group were significantly higher than the I/R group. There was also significant difference between the sham and AGE groups in terms of total antioxidant enzyme levels. Furthermore, AGE treatment significantly reduced the inflammatory cytokines and caspase-3 activity than the I/R group. This study demonstrates the considerable neuroprotective effect of AGE on the neurological, pathological, ultrastructural, and biochemical status of rats with I/R-induced spinal cord injury. PMID:27183321

  1. Inference and forecasting in the age-period-cohort model with unknown exposure with an application to mesothelioma mortality

    OpenAIRE

    Martinez-Miranda, M. D.; Nielsen, B; J.P. Nielsen

    2014-01-01

    It is of considerable interest to forecast future mesothelioma mortality. No measures for exposure are available so it is not straight forward to apply a dose-response model. It is proposed to model the counts of deaths directly using a Poisson regression with an age-period-cohort structure, but without offset. Traditionally the age-period-cohort is viewed to suffer from an identification problem. It is shown how to re-parameterize the model in terms of freely varying parameters, so as to avo...

  2. Age Dependent 3-D Magnetic Modeling of the North Pacific and North Atlantic Oceanic Crust at Intermediate Wavelengths

    Science.gov (United States)

    Yanez, Gonzalo A.; LaBrecque, John L.

    1996-01-01

    Three-dimensional magnetic modeling of the North Atlantic and Northeast pacific is performed at intermediate wavelengths using three models for the acquisition of a natural remanent magnetization. It is shown that a remanent magnetization which is dependent on the rustal age is the dominant source for the intermediate wavelength pattern in both basins.

  3. Hierarchical Linear Modeling Analyses of NEO-PI-R Scales In the Baltimore Longitudinal Study of Aging

    Science.gov (United States)

    Terracciano, Antonio; McCrae, Robert R.; Brant, Larry J.; Costa, Paul T.

    2009-01-01

    We examined age trends in the five factors and 30 facets assessed by the Revised NEO Personality Inventory in Baltimore Longitudinal Study of Aging data (N = 1,944; 5,027 assessments) collected between 1989 and 2004. Consistent with cross-sectional results, Hierarchical Linear Modeling analyses showed gradual personality changes in adulthood: a decline up to age 80 in Neuroticism, stability and then decline in Extraversion, decline in Openness, increase in Agreeableness, and increase up to age 70 in Conscientiousness. Some facets showed different curves from the factor they define. Birth cohort effects were modest, and there were no consistent Gender × Age interactions. Significant non-normative changes were found for all five factors; they were not explained by attrition but might be due to genetic factors, disease, or life experience. PMID:16248708

  4. Developing an Age Model for the Cryogenian: the South China perspective

    Science.gov (United States)

    Condon, D. J.; Zhu, M.; Macdonald, F. A.; Tapster, S.

    2014-12-01

    The Neoproterozoic stratigraphic record of South China contains distributed volcanic ash beds, which can be dated and used to provide a backbone for Cryogenian and Ediacaran 'age models'. When integrated with geochemical and paleontological data, both locally and from other regions, these successions inform our understanding of environmental and biological change from these intervals. At present the South China stratigraphy provides the dates that best approximate the termination of the Marinoan glaciation (ca. 635 Ma, U-Pb single zircon isotope dilution1) from a dated volcanic ash bed that occurs in the cap carbonate sequence (Doushantuo Formation) which directly overlies the Nantuo Tillite (Marinoan glaciation equivalent). A number of other ash beds have been documented in both the Nantuo Tillite and throughout the Datangpo Formation (pre-Marinoan non-glacial succession) and have been variably dated using U-Pb microbeam and multi-grain isotope dilution studies2-4. These published data sets have produced dates that have uncertainties on the order of 4 Myr but are built upon single-analyses data points, which have uncertainties on the order of 10 Myr or greater thereby limiting their utility for assessing temporal relationship with other dated section. We present new U-Pb single zircon isotope dilution geochronology data from a suite of samples from the Datangpo, Nantuo and Doushantuo Formations. New dates from the base of the Datangpo Formation confirm a ca. 660 Ma end to the Sturtian glacial epoch, which is represented by underlying glacial deposits. Additional dates from ash beds from the Datangpo Formation and the lower Nantuo Tillite will refine the duration of the Cryogenian non-glacial interlude and Marinoan glaciation as recorded in South China. Combined with published data from Namibia, Australia and Canada, these new data will permit the development of a more highly resolved age model for the Cryogenian, enabling estimation of duration and synchronicity

  5. Career-Related Variables and Planned Retirement Age: An Extension of Beehr's Model.

    Science.gov (United States)

    Adams, Gary A.

    1999-01-01

    A study of 172 older workers found that career commitment and occupational-goal attainment play a central role in planned retirement age. Age and retirement-income satisfaction had the most significant relationship to planned retirement age. Job satisfaction was not strongly related to retirement intentions. (SK)

  6. A review of successful aging models: proposing proactive coping as an important additional strategy.

    NARCIS (Netherlands)

    Ouwehand, C.; Ridder, D.T.D. de; Bensing, J.M.

    2007-01-01

    Successful aging is an important concept, and one that has been the subject of much research. During the last 15 years, the emphasis of this research has shifted from formulating criteria for successful aging to describing the processes involved in successful aging. The main purpose of the present a

  7. A review of successful aging models: Proposing proactive coping as an important additional strategy

    NARCIS (Netherlands)

    Ouwehand, C.; Ridder, D.T.D. de; Bensing, J.

    2007-01-01

    Successful aging is an important concept, and one that has been the subject of much research. During the last 15 years, the emphasis of this research has shifted from formulating criteria for successful aging to describing the processes involved in successful aging. The main purpose of the present a

  8. Ice-age survival of Atlantic cod: agreement between palaeoecology models and genetics

    Science.gov (United States)

    Bigg, Grant R; Cunningham, Clifford W; Ottersen, Geir; Pogson, Grant H; Wadley, Martin R; Williamson, Phillip

    2007-01-01

    Scant scientific attention has been given to the abundance and distribution of marine biota in the face of the lower sea level, and steeper latitudinal gradient in climate, during the ice-age conditions that have dominated the past million years. Here we examine the glacial persistence of Atlantic cod (Gadus morhua) populations using two ecological-niche-models (ENM) and the first broad synthesis of multi-locus gene sequence data for this species. One ENM uses a maximum entropy approach (Maxent); the other is a new ENM for Atlantic cod, using ecophysiological parameters based on observed reproductive events rather than adult distribution. Both the ENMs were tested for present-day conditions, then used to hindcast ranges at the last glacial maximum (LGM) ca 21 kyr ago, employing climate model data. Although the LGM range of Atlantic cod was much smaller, and fragmented, both the ENMs agreed that populations should have been able to persist in suitable habitat on both sides of the Atlantic. The genetic results showed a degree of trans-Atlantic divergence consistent with genealogically continuous populations on both sides of the North Atlantic since long before the LGM, confirming the ENM results. In contrast, both the ENMs and the genetic data suggest that the Greenland G. morhua population post-dates the LGM. PMID:17999951

  9. Lithium prevents parkinsonian behavioral and striatal phenotypes in an aged parkin mutant transgenic mouse model.

    Science.gov (United States)

    Lieu, Christopher A; Dewey, Colleen M; Chinta, Shankar J; Rane, Anand; Rajagopalan, Subramanian; Batir, Sean; Kim, Yong-Hwan; Andersen, Julie K

    2014-12-01

    Lithium has long been used as a treatment for the psychiatric disease bipolar disorder. However, previous studies suggest that lithium provides neuroprotective effects in neurodegenerative diseases such as Parkinson's disease (PD) and Alzheimer's disease. The exact mechanism by which lithium exerts these effects still remains unclear. In the present study, we evaluated the effects of low-dose lithium treatment in an aged mouse model expressing a parkin mutation within dopaminergic neurons. We found that low-dose lithium treatment prevented motor impairment as demonstrated by the open field test, pole test, and rearing behavior. Furthermore, lithium prevented dopaminergic striatal degeneration in parkin animals. We also found that parkin-induced striatal astrogliosis and microglial activation were prevented by lithium treatment. Our results further corroborate the use of this parkin mutant transgenic mouse line as a model for PD for testing novel therapeutics. The findings of the present study also provide further validation that lithium could be re-purposed as a therapy for PD and suggest that anti-inflammatory effects may contribute to its neuroprotective mechanisms. PMID:25452026

  10. Geo-spatial modelling with unbalanced data: modelling the spatial pattern of human activity during the Stone Age

    Science.gov (United States)

    Jasiewicz, Jarosław; Sobkowiak-Tabaka, Iwona

    2015-08-01

    With the increasing availability of data, geoscience provides many methods to model the spatial extent of various phenomena.Acquiring representative, high quality data is the most important criterion to assess the value of any spatial analysis, however, there are many situations in which these criteria cannot be fulfilled. Archived data, collected in the past, for which analysis cannot be repeated or supplemented is a very common information source. Archaeological data collected at a regional extent during years of field work and superficial observations are an additional example. Such data rarely provide representative samples and are usually imbalanced; only very few examples contain useful data, while many examples remain without any archaeological traces. In spite of these limitations archaeological information presented in the form of maps can be a useful and helpful tool to analyse the spatial patterns of some phenomena and, from a more practical point of view, a tool to predict the location of undiscovered occurrences. The primary goal of this paper is to present a methodology for modelling spatial patterns based on imbalanced categorical data which do not fulfil the criteria of spatial representation and incorporates uncertainty in its decision process. This concept will be discussed using a collection of Stone Age sites and set of environmental variables from the postglacial lowlands in Western Poland. We will propose a machine-learning system which adopts CART through bootstrap simulation to incorporate uncertainty into the spatial model and utilise that uncertainty in the decision-making process. Finally, we will describe the relationships between the model and environmental variables and present our results in cartographic form using the principles of decision-tree cartography.

  11. Transplanted Adipose-Derived Stem Cells Ameliorate Testicular Dysfunction In A D-Galactose-Induced Aging Rat Model.

    Science.gov (United States)

    Yang, Chun; Du, Yi-Kuan; Wang, Jun; Luan, Ping; Yang, Qin-Lao; Huang, Wen-Hua; Yuan, Lin

    2015-10-01

    Glycation product accumulation during aging of slowly renewing tissues may be an important mechanism underlying aging of the testis. Adipose-derived stem cells (ADSCs) have shown promise in a novel tissue regenerative technique and may have utility in treating sexual dysfunction. ADSCs have also been found to be effective in antiaging therapy, although the mechanism underlying their effects remains unknown. This study was designed to investigate the anti-aging effect of ADSCs in a D-galactose (D-gal)-induced aging animal model and to clarify the underlying mechanism. Randomly selected 6-week-old male Sprague-Dawley rats were subcutaneously injected with D-gal daily for 8 weeks. Two weeks after completion of treatment, D-gal-induced aging rats were randomized to receive caudal vein injections of 3 × 10(6) 5-bromo 2'deoxy-uridine-labeled ADSCs or an equal volume of phosphate-buffered saline. Serum testosterone level, steroidogenic enzymes (3-β-hydroxysteroid dehydrogenase), and superoxide dismutase (SOD) activity decreased significantly in aging rats compared with the control group; serum lipid peroxidation, spermatogenic cell apoptosis, and methane dicarboxylic aldehyde (MDA) expression increased significantly. ADSCs increased the SOD level and reduced the MDA level in the aging animal model and restored levels of serum testosterone, steroidogenic enzymes, and spermatogenic cell apoptosis. These results demonstrate that ADSCs can contribute to testicular regeneration during aging. ADSCs also provide functional benefits through glycation suppression and antioxidant effects in a rat model of aging. Although some ADSCs differentiated into Leydig cells, the paracrine pathway seems to play a main role in this process, resulting in the reduction of apoptosis. PMID:25728126

  12. CONSTRAINING STELLAR POPULATION MODELS. I. AGE, METALLICITY AND ABUNDANCE PATTERN COMPILATION FOR GALACTIC GLOBULAR CLUSTERS

    International Nuclear Information System (INIS)

    We present an extensive literature compilation of age, metallicity, and chemical abundance pattern information for the 41 Galactic globular clusters (GGCs) studied by Schiavon et al. Our compilation constitutes a notable improvement over previous similar work, particularly in terms of chemical abundances. Its primary purpose is to enable detailed evaluations of and refinements to stellar population synthesis models designed to recover the above information for unresolved stellar systems based on their integrated spectra. However, since the Schiavon sample spans a wide range of the known GGC parameter space, our compilation may also benefit investigations related to a variety of astrophysical endeavors, such as the early formation of the Milky Way, the chemical evolution of GGCs, and stellar evolution and nucleosynthesis. For instance, we confirm with our compiled data that the GGC system has a bimodal metallicity distribution and is uniformly enhanced in the α elements. When paired with the ages of our clusters, we find evidence that supports a scenario whereby the Milky Way obtained its globular clusters through two channels: in situ formation and accretion of satellite galaxies. The distributions of C, N, O, and Na abundances and the dispersions thereof per cluster corroborate the known fact that all GGCs studied so far with respect to multiple stellar populations have been found to harbor them. Finally, using data on individual stars, we verify that stellar atmospheres become progressively polluted by CN(O)-processed material after they leave the main sequence. We also uncover evidence which suggests that the α elements Mg and Ca may originate from more than one nucleosynthetic production site. We estimate that our compilation incorporates all relevant analyses from the literature up to mid-2012. As an aid to investigators in the fields named above, we provide detailed electronic tables of the data upon which our work is based at http

  13. Carnosine and taurine treatments diminished brain oxidative stress and apoptosis in D-galactose aging model.

    Science.gov (United States)

    Aydın, A Fatih; Çoban, Jale; Doğan-Ekici, Işın; Betül-Kalaz, Esra; Doğru-Abbasoğlu, Semra; Uysal, Müjdat

    2016-04-01

    D-galactose (GAL) has been used as an animal model for brain aging and antiaging studies. GAL stimulates oxidative stress in several tissues including brain. Carnosine (CAR; β-alanil-L-histidine) and taurine (TAU; 2-aminoethanesulfonic acid) exhibit antioxidant properties. CAR and TAU have anti-aging and neuroprotective effects. We investigated the effect of CAR and TAU supplementations on oxidative stress and brain damage in GAL-treated rats. Rats received GAL (300 mg/kg; s.c.; 5 days per week) alone or together with CAR (250 mg/kg/daily; i.p.; 5 days per week) or TAU (2.5% w/w; in rat chow) for 2 months. Brain malondialdehyde (MDA), protein carbonyl (PC) and glutathione (GSH) levels and superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), glutathione transferase (GST) and acetylcholinesterase (AChE) activities were determined. Expressions of B cell lymphoma-2 (Bcl-2), Bax and caspase-3 were also evaluated in the brains by immunohistochemistry. GAL treatment increased brain MDA and PC levels and AChE activities. It decreased significantly brain GSH levels, SOD and GSH-Px but not GST activities. GAL treatment caused histopathological changes and increased apoptosis. CAR and TAU significantly reduced brain AChE activities, MDA and PC levels and elevated GSH levels in GAL-treated rats. CAR, but not TAU, significantly increased low activities of SOD and GSH-Px. Both CAR and TAU diminished apoptosis and ameliorated histopathological findings in the brain of GAL-treated rats. Our results indicate that CAR and TAU may be effective to prevent the development of oxidative stress, apoptosis and histopathological deterioration in the brain of GAL-treated rats. PMID:26518192

  14. An age-based replacement model for repairable systems with attention to high-speed marine diesel engines

    OpenAIRE

    Harlem, Alf

    2008-01-01

    The background of this thesis is the high number of severe failures of high-speed propulsion engines in high-speed vessels. When number of failures is high, the preventive maintenance comes into particular focus. Hence, this study will consider the interval (age), at which to carry out scheduled engine replacement or renewal by overhaul.The main objective shall be to develop a new age-based replacement model for repairable systems that combines system reliability theory with observed system f...

  15. The effect of family-centered empowerment model on quality of life of school–aged children with thalassemia major

    OpenAIRE

    Borhani, Fariba; Najafi, Maral Kargar; Rabori, Eshaq Dortaj; Sabzevari, Sakkineh

    2011-01-01

    BACKGROUND: Chronic nature of thalassemia causes changes in different aspects of life in patients, including their quality of life. Because of the important role of family in caring for children with thalassemia, this study was done to evaluate the effect of family-centered empowerment model on quality of life of the children aged 6-12 years with thalassemia in Kerman Thalassemia Center. METHODS: The present experimental study was carried out on 86 thalassemic children aged 6-12 years who wer...

  16. Oogonial stem cells as a model to study age-associated infertility in women

    Science.gov (United States)

    Garg, Neha; Sinclair, David A.

    2016-01-01

    Fertility is the first biological process to break down during aging, thereby making it a useful tool to understand fundamental processes of aging. Reproductive aging in females is associated with a loss of ovarian function characterised by a reduction in the number and quality of oocytes. The central dogma, namely that females are born with a fixed pool of oocytes that progressively decline with increasing maternal age, has been challenged by evidence supporting postnatal oogenesis in mammals. Reports demonstrating formation of new oocytes from newly discovered germline stem cells, referred to as oogonial stem cells (OSCs), has opened new avenues for treatment of female infertility. In this review we discuss why the OSCs possibly lose their regenerative potential over time, and focus specifically on the aging process in germline stem cells as a possible mechanism for understanding female age-related infertility and how we can slow or delay ovarian aging. PMID:25897831

  17. Oogonial stem cells as a model to study age-associated infertility in women.

    Science.gov (United States)

    Garg, Neha; Sinclair, David A

    2015-07-01

    Fertility is the first biological process to break down during aging, thereby making it a useful tool to understand fundamental processes of aging. Reproductive aging in females is associated with a loss of ovarian function characterised by a reduction in the number and quality of oocytes. The central dogma, namely that females are born with a fixed pool of oocytes that progressively decline with increasing maternal age, has been challenged by evidence supporting postnatal oogenesis in mammals. Reports demonstrating formation of new oocytes from newly discovered germline stem cells, referred to as oogonial stem cells (OSCs), has opened new avenues for treatment of female infertility. In this review we discuss why the OSCs possibly lose their regenerative potential over time, and focus specifically on the aging process in germline stem cells as a possible mechanism for understanding female age-related infertility and how we can slow or delay ovarian aging. PMID:25897831

  18. Implementation of an active aging model in Mexico for prevention and control of chronic diseases in the elderly

    Directory of Open Access Journals (Sweden)

    Correa-Muñoz Elsa

    2009-08-01

    Full Text Available Abstract Background World Health Organization cites among the main challenges of populational aging the dual disease burden: the greater risk of disability, and the need for care. In this sense, the most frequent chronic diseases during old age worldwide are high blood pressure, type 2 diabetes mellitus, cancer, arthritis, osteoporosis, depression, and dementia. Chronic disease-associated dependency represents an onerous sanitary and financial burden for the older adult, the family, and the health care system. Thus, it is necessary to propose community-level models for chronic disease prevention and control in old age. The aim of the present work is to show our experience in the development and implementation of a model for chronic disease prevention and control in old age at the community level under the active aging paradigm. Methods/Design A longitudinal study will be carried out in a sample of 400 elderly urban and rural-dwelling individuals residing in Hidalgo State, Mexico during five years. All participants will be enrolled in the model active aging. This establishes the formation of 40 gerontological promoters (GPs from among the older adults themselves. The GPs function as mutual-help group coordinators (gerontological nuclei and establish self-care and self-promotion actions for elderly well-being and social development. It will be conformed a big-net of social network of 40 mutual-help groups of ten elderly adults each one, in which self-care is a daily practice for chronic disease prevention and control, as well as for achieving maximal well-being and life quality in old age. Indicators of the model's impact will be (i therapeutic adherence; (ii the incidence of the main chronic diseases in old age; (iii life expectancy without chronic diseases at 60 years of age; (iv disability adjusted life years lost; (v years of life lost due to premature mortality, and (vi years lived with disability. Discussion We propose that the

  19. Improvements in the biokinetic model for strontium with allowance for age and gender differences in bone mineral metabolism

    Energy Technology Data Exchange (ETDEWEB)

    Shagina, N.B.; Tolstykh, E.I.; Degteva, M.O

    2003-07-01

    An age- and gender-dependent biokinetic model for strontium was developed based on the study of a population living along the Techa River exposed to effluents from the Mayak Production Association. To estimate parameters of a new model (Techa biokinetic model, TBM) many data sets have been assembled: our whole-body counter data on long-term retention of {sup 90}Sr in humans, data from studies during the period of global fallout, data resulting from deliberate injections of strontium radionuclides, and non-radiological data regarding bone formation and resorption, mineral content of the body, etc. The model was developed using the basic structure of the ICRP biokinetic model for strontium, but new age- and gender-specific parameters were derived. This paper discusses the approaches applied to develop the new model. (author)

  20. Improvements in the biokinetic model for strontium with allowance for age and gender differences in bone mineral metabolism

    International Nuclear Information System (INIS)

    An age- and gender-dependent biokinetic model for strontium was developed based on the study of a population living along the Techa River exposed to effluents from the Mayak Production Association. To estimate parameters of a new model (Techa biokinetic model, TBM) many data sets have been assembled: our whole-body counter data on long-term retention of 90Sr in humans, data from studies during the period of global fallout, data resulting from deliberate injections of strontium radionuclides, and non-radiological data regarding bone formation and resorption, mineral content of the body, etc. The model was developed using the basic structure of the ICRP biokinetic model for strontium, but new age- and gender-specific parameters were derived. This paper discusses the approaches applied to develop the new model. (author)

  1. Age-dependent decline in learning and memory performances of WAG/Rij rat model of absence epilepsy

    Directory of Open Access Journals (Sweden)

    Karson Ayşe

    2012-09-01

    Full Text Available Abstract Recent clinical studies revealed emotional and cognitive impairments associated with absence epilepsy. Preclinical research with genetic models of absence epilepsy however have primarily focused on dysfunctional emotional processes and paid relatively less attention to cognitive impairment. In order to bridge this gap, we investigated age-dependent changes in learning and memory performance, anxiety-like behavior, and locomotor activity of WAG/Rij rats (a valid model of generalized absence epilepsy using passive avoidance, Morris water maze, elevated plus maze, and locomotor activity cage. We tested 5 month-old and 13 month-old WAG/Rij rats and compared their performance to age-matched Wistar rats. Results revealed a decline in emotional and spatial memory of WAG/Rij rats compared to age-matched Wistar rats only at 13 months of age. Importantly, there were no significant differences between WAG/Rij and Wistar rats in terms of anxiety-like behavior and locomotor activity at either age. Results pointed at age-dependent learning and memory deficits in the WAG/Rij rat model of absence epilepsy.

  2. Sm-Nd model age evidence for temporally distinct precambrian crustal blocks across the Cauvery shear zone, Southern India

    International Nuclear Information System (INIS)

    Over the last decade, Sm-Nd model age mapping has been successfully used for deciphering temporally distinct crustal domains in many complex Precambrian terrains. The Sm-Nd model ages combined with age data by other methods, such as U-Pb zircon, form a powerful approach for constraining timing of crust formation in Precambrian poly-metamorphic terrains. When used judiciously, the Sm-Nd model ages (generally depleted mantle ages, TDM), could relate to the time of extraction of magmatic protoliths from the upper mantle. A large database of new Sm-Nd and Rb-Sr isotopic analyses (86 samples) on Precambrian basement gneisses (mainly charnockite gneisses) along a wide corridor representing a N-S cross section across the Cauvery Shear Zone (CSZ), of the Southern Granulite Terrain (SGT), South India are considered here. Spatial distribution of the crust-formation ages is considered mainly in terms of: (1) deciphering temporally distinct crustal blocks across the CSZ and (2) the tectonic significance of the CSZ both in the regional and global (Gondwana) perspective

  3. Tracer kinetics: Modelling by partial differential equations of inhomogeneous compartments with age-dependent elimination rates. Pt. 2

    International Nuclear Information System (INIS)

    The general theory of inhomogeneous compartments with age-dependent elimination rates is illustrated by examples. Mathematically, it turns out that models consisting of partial differential equations include ordinary, delayed and integro-differential equations, a general fact which is treated here in the context of linear tracer kinetics. The examples include standard compartments as a degenerate case, systems of standard compartments (compartment blocks), models resulting in special residence time distributions, models with pipes, and systems with heterogeneous particles. (orig./BBR)

  4. Effect of age of dam on weight of calf in the genetic assessment of Zebu cattle in random regression models

    OpenAIRE

    Jorge Luis Ferreira; Fernando Brito Lopes; Tiago Bresolin; José Américo Soares Garcia; Silvia Minharro; Raysildo Barbosa Lôbo

    2015-01-01

    Current analysis estimated co-variance components and genetic parameters for growth traits by random regression models taking into consideration the cow’s age on the weight of calves. Genealogical data and records on weights of male and female Zebu cattle, born between 1993 and 2011, were provided by the National Association of Breeders and Researchers (ANCP). Different models were compared by Akaike and Bayesian criteria. Legendre’s orthogonal polynomials were used to model the direct and ma...

  5. Terrestrial astronomical age model for Eocene Thermal Maximum 2 and H2 hyperthermal events

    Science.gov (United States)

    Abels, Hemmo; Lourens, Lucas; Gingerich, Philip

    2013-04-01

    Knowledge of the duration and the rates of onset and recovery of early Paleogene hyperthermal events is crucial for understanding Earth's system response to massive input of greenhouse gases into the exogenic carbon pool. The second largest hyperthermal, Eocene Thermal Maximum 2 (ETM2), and its immediate successor H2 occur around 54 million years ago. Relative chronologies have been constructed for ETM2 and H2 in deep-sea records at Walvis Ridge in the southern Atlantic Ocean (Stap et al. 2009). Here, we construct an independent astronomical age model for these hyperthermals in terrestrial successions in the Bighorn Basin, Wyoming (Abels et al. 2012). We first generated parallel carbon isotope records of the ETM2-H2 interval in the Creek Star Hill, West Branch, and Purple Butte sections located between 1 and 3 km of the previously analyzed Upper Deer Creek (UDC) section. The carbon isotope patterns in the three new sections mimic both in time and magnitude the ETM2-H2 carbon isotope patterns from the UDC section. This confirms the reproducibility of the carbon isotope time series in these floodplain successions. The four sections were subsequently correlated by lateral tracing of distinctive paleosol horizons representing time lines at the sub-precession time scale. The correlation was confirmed by overbank-avulsion sedimentation cycles coevally occurring in the four sections. The constructed stratigraphic fence panel allows disentangling local fluvial variability in sedimentation from the regional signal. Coeval overbank-avulsion cyclicity at the precession time scale (Abels et al. 2013) are then used to construct an astronomical age model for the ETM2-H2 hyperthermal events. References Abels, H.A., W.C. Clyde, P.D. Gingerich, F.J. Hilgen, H.C. Fricke, G.J. Bowen, L.J. Lourens, 2012. Terrestrial carbon isotope excursions and biotic change during Palaeogene hyperthermals. Nature Geoscience 5, 326-329. Abels, H.A., M.J. Kraus, P.D. Gingerich, 2013. Precession

  6. Stochastic modeling indicates that aging and somatic evolution in the hematopoetic system are driven by non-cell-autonomous processes.

    Science.gov (United States)

    Rozhok, Andrii I; Salstrom, Jennifer L; DeGregori, James

    2014-12-01

    Age-dependent tissue decline and increased cancer incidence are widely accepted to be rate-limited by the accumulation of somatic mutations over time. Current models of carcinogenesis are dominated by the assumption that oncogenic mutations have defined advantageous fitness effects on recipient stem and progenitor cells, promoting and rate-limiting somatic evolution. However, this assumption is markedly discrepant with evolutionary theory, whereby fitness is a dynamic property of a phenotype imposed upon and widely modulated by environment. We computationally modeled dynamic microenvironment-dependent fitness alterations in hematopoietic stem cells (HSC) within the Sprengel-Liebig system known to govern evolution at the population level. Our model for the first time integrates real data on age-dependent dynamics of HSC division rates, pool size, and accumulation of genetic changes and demonstrates that somatic evolution is not rate-limited by the occurrence of mutations, but instead results from aged microenvironment-driven alterations in the selective/fitness value of previously accumulated genetic changes. Our results are also consistent with evolutionary models of aging and thus oppose both somatic mutation-centric paradigms of carcinogenesis and tissue functional decline. In total, we demonstrate that aging directly promotes HSC fitness decline and somatic evolution via non-cell-autonomous mechanisms. PMID:25564763

  7. Modeling Fetal Weight for Gestational Age: A Comparison of a Flexible Multi-level Spline-based Model with Other Approaches

    OpenAIRE

    Villandré, Luc; Hutcheon, Jennifer A; Perez Trejo, Maria Esther; Abenhaim, Haim; Jacobsen, Geir; Platt, Robert W.

    2011-01-01

    We present a model for longitudinal measures of fetal weight as a function of gestational age. We use a linear mixed model, with a Box-Cox transformation of fetal weight values, and restricted cubic splines, in order to flexibly but parsimoniously model median fetal weight. We systematically compare our model to other proposed approaches. All proposed methods are shown to yield similar median estimates, as evidenced by overlapping pointwise confidence bands, except after 40 completed weeks, w...

  8. Metabolic Free Energy and Biological Codes: A 'Data Rate Theorem' Aging Model.

    Science.gov (United States)

    Wallace, Rodrick

    2015-06-01

    A famous argument by Maturana and Varela (Autopoiesis and cognition. Reidel, Dordrecht, 1980) holds that the living state is cognitive at every scale and level of organization. Since it is possible to associate many cognitive processes with 'dual' information sources, pathologies can sometimes be addressed using statistical models based on the Shannon Coding, the Shannon-McMillan Source Coding, the Rate Distortion, and the Data Rate Theorems, which impose necessary conditions on information transmission and system control. Deterministic-but-for-error biological codes do not directly invoke cognition, but may be essential subcomponents within larger cognitive processes. A formal argument, however, places such codes within a similar framework, with metabolic free energy serving as a 'control signal' stabilizing biochemical code-and-translator dynamics in the presence of noise. Demand beyond available energy supply triggers punctuated destabilization of the coding channel, affecting essential biological functions. Aging, normal or prematurely driven by psychosocial or environmental stressors, must interfere with the routine operation of such mechanisms, initiating the chronic diseases associated with senescence. Amyloid fibril formation, intrinsically disordered protein logic gates, and cell surface glycan/lectin 'kelp bed' logic gates are reviewed from this perspective. The results generalize beyond coding machineries having easily recognizable symmetry modes, and strip a layer of mathematical complication from the study of phase transitions in nonequilibrium biological systems. PMID:25185747

  9. Aging and serum MCP-1 are associated with gut microbiome composition in a murine model

    OpenAIRE

    Conley, Melissa N.; Wong, Carmen P.; Duyck, Kyle M.; Hord, Norman; Ho, Emily; Sharpton, Thomas J

    2016-01-01

    Introduction. Age is the primary risk factor for major human chronic diseases, including cardiovascular disorders, cancer, type 2 diabetes, and neurodegenerative diseases. Chronic, low-grade, systemic inflammation is associated with aging and the progression of immunosenescence. Immunosenescence may play an important role in the development of age-related chronic disease and the widely observed phenomenon of increased production of inflammatory mediators that accompany this process, referred ...

  10. Copper deficiency: A potential model for determining the role of mitochondria in cardiac aging

    OpenAIRE

    Johnson, W. Thomas; Newman, Samuel M.

    2003-01-01

    Heart mitochondria experience age-related declines in cytochrome c oxidase (CCO) activity and increases in the generation of reactive oxygen species (ROS) that may contribute to loss of cardiac function and the development of disease that occur with advancing age. In a manner similar to aging, copper deficiency also suppresses heart CCO activity and has cardiovascular consequences related to increased peroxidation. Food restriction is often used as a tool to study oxidative mechanisms of agin...

  11. Thermal aging modeling and validation on the Mo containing Fe-Cr-Ni alloys

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ying [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Tan, Lizhen [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Busby, Jeremy T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-04-01

    Thermodynamics of intermetallic phases in Fe-rich Fe-Cr-Ni-Mo alloys is critical knowledge to understand thermal aging effect on the phase stability of Mo-containing austenitic steels, which subsequently facilitates alloy design/improvement and degradation mitigation of these materials for reactor applications. Among the intermetallic phases, Chi (χ), Laves, and Sigma (σ) are often of concern because of their tendency to cause embrittlement of the materials. The focus of this study is thermal stability of the Chi and Laves phases as they were less studied compared to the Sigma phase. Coupled with thermodynamic modeling, thermal stability of intermetallic phases in Mo containing Fe-Cr-Ni alloys was investigated at 1000, 850 and 700 C for different annealing times. The morphologies, compositions and crystal structures of the precipitates of the intermetallic phases were carefully examined by scanning electron microscopy, electron probe microanalysis, X-ray diffraction, and transmission electron microscopy. Three key findings resulted from this study. First, the Chi phase is stable at high temperature, and with decreasing temperature it transforms into the Laves phase that is stable at low temperature. Secondly, Cr, Mo, Ni are soluble in both the Chi and Laves phases, with the solubility of Mo playing a major role in the relative stability of the intermetallic phases. Thirdly, in situ transformation from Chi phase to Laves phase was directly observed, which increased the local strain field, generated dislocations in the intermetallic phases, and altered the precipitate phase orientation relationship with the austenitic matrix. The thermodynamic models that were developed and validated were then applied to evaluating the effect of Mo on the thermal stability of intermetallic phases in type 316 and NF709 stainless steels.

  12. Glutamatergic signaling and low prodynorphin expression are associated with intact memory and reduced anxiety in rat models of healthy aging

    Directory of Open Access Journals (Sweden)

    Caroline eMenard

    2014-05-01

    Full Text Available The LOU/C/Jall (LOU rat strain is considered a model of healthy aging due to its increased longevity, maintenance of stable body weight (BW throughout life and low incidence of age-related diseases. However, aging LOU rat cognitive and anxiety status has yet to be investigated. In the present study, male and female LOU rat cognitive performances (6-42 months were assessed using novel object recognition and Morris Water Maze tasks. Recognition memory remained intact in all LOU rats up to 42 months of age. As for spatial memory, old LOU rat performed similarly as young animals for learning acquisition, reversal learning and retention. While LOU rat BW remained stable despite aging, 20-month-old ad-libitum-fed (OAL male Sprague Dawley rats become obese. We determined if long-term caloric restriction (LTCR prevents age-related BW increase and cognitive deficits in this rat strain, as observed in the obesity-resistant LOU rats. Compared to young animals, recognition memory was impaired in OAL but intact in 20-month-old calorie-restricted (OCR rats. Similarly, OAL spatial learning acquisition was impaired but LTCR prevented the deficits. Exacerbated stress responses may favor age-related cognitive decline. In the elevated plus maze and open field tasks, LOU and OCR rats exhibited high levels of exploratory activity whereas OAL rats displayed anxious behaviors. Expression of prodynorphin (Pdyn, an endogenous peptide involved in stress-related memory impairments, was increased in the hippocampus of OAL rats. Group 1 metabotropic glutamate receptor 5 and immediate early genes Homer 1a and Arc expression, both associated with successful cognitive aging, were unaltered in aging LOU rats but lower in OAL than OCR rats. Altogether, our results, supported by principal component analysis and correlation matrix, suggest that intact memory and low anxiety are associated with glutamatergic signaling and low Pdyn expression in the hippocampus of non obese aging

  13. A Drosophila model for age-associated changes in sleep:wake cycles

    OpenAIRE

    Koh, Kyunghee; Evans, Joshua M.; Hendricks, Joan C.; Sehgal, Amita

    2006-01-01

    One of the most consistent behavioral changes that occurs with age in humans is the loss of sleep consolidation. This can be quite disruptive and yet little is known about its underlying basis. To better understand the effects of aging on sleep:wake cycles, we sought to study this problem in Drosophila melanogaster, a powerful system for research on aging and behavior. By assaying flies of different ages as well as monitoring individual flies constantly over the course of their lifetime, we f...

  14. Long-term Neuroglial Cocultures as a Brain Aging Model: Hallmarks of Senescence, MicroRNA Expression Profiles, and Comparison With In Vivo Models.

    Science.gov (United States)

    Bigagli, Elisabetta; Luceri, Cristina; Scartabelli, Tania; Dolara, Piero; Casamenti, Fiorella; Pellegrini-Giampietro, Domenico E; Giovannelli, Lisa

    2016-01-01

    Our purpose was to evaluate long-term neuroglial cocultures as a model for investigating senescence in the nervous system and to assess its similarities with in vivo models. To this aim, we maintained the cultures from 15 days in vitro (mature cultures) up to 27 days in vitro (senescent cultures), measuring senescence-associated, neuronal, dendritic, and astrocytic markers. Whole microRNA expression profiles were compared with those measured in the cortex of 18- and 24-month-old C57Bl/6J aged mice and of transgenic TgCRND8 mice, a model of amyloid-β deposition. Neuroglial cocultures displayed features of cellular senescence (increased senescence-associated-β-galactosidase activity, oxidative stress, γ-H2AX expression, IL-6 production, astrogliosis) that were concentration dependently counteracted by the antiaging compound resveratrol (1-5 µM). Among the 1,080 microRNAs analyzed, 335 were downregulated or absent in 27 compared with 15 days in vitro and resveratrol reversed this effect. A substantial overlapping was found between age-associated changes in microRNA expression profiles in vitro and in TgCRND8 mice but not in physiologically aged mice, indicating that this culture model displays more similarities with pathological than physiological brain aging. Our results demonstrate that neuroglial cocultures aged in vitro can be useful for investigating the cellular and molecular mechanisms of brain aging and for preliminary testing of protective compounds. PMID:25568096

  15. Application of dynamic system reliability methods for incorporation of age-dependant reliability parameters and data into the PSA model

    International Nuclear Information System (INIS)

    The simplest way to quantify reliability models consists in using the hypothesis that SSC failure and repair rates are constant. However, failures and repairs are implemented in time and consequently they are age-dependent. That is why the dynamic aspects of aging and decision-making in NPP lifetime management become increasingly notable and more advanced tools are needed for their analysis. The paper presents the dynamic system reliability approaches - GO-FLOW and ATRD - to extend the FT methodology for NPP aging systems. Alternative methodologies to investigate the feasibility of increasing of failure, restore and repair rates of all component categories or reducing the surveillance intervals of repairable components to take into account aging processes in plant availability. Both approaches are used for preparation of comparable aging process component and system models of the three-train residual heat removal and low pressure injection system of a Russian-design pressurized water reactor WWER-1000/V320. The possible extensions of these methodologies are compared with the equivalent FT models of this system. (author)

  16. A new correction model for 14C ages in aquifers with complex geochemistry - Application to the Neogene Aquifer, Belgium

    International Nuclear Information System (INIS)

    The objective of this paper is to build a general correction model that takes into account all the different radiocarbon-dilution reactions and resolving the processes that are geochemically 'aging' the groundwater in the Neogene Aquifer. For this, δ13C and radiocarbon in groundwater are investigated with their relationship to other chemical components in groundwater. The δ13C values in the Neogene Aquifer are influenced by various geochemical reactions like calcite dissolution, oxidation of organic matter and methanogenesis. Calcite dissolution and CH4 production increase δ13C while the oxidation of organic matter decreases δ13C in the groundwater. The reactions that modify δ13C also influence the 14C activity. Due to the complex geochemical environment, existing correction models are not applicable to this situation. A correction model for initial 14C activity is formulated in which the different C sources that influence 14C activity are taken into account. It is observed that recent dissolved organic matter plays an important role in redox reactions. The corrected 14C ages lie between -0.792 and 6.425 ka representing the maximum age. If a part of the organic matter that oxidises is fossil, the determined age will represent an overestimated age.

  17. Age and reemployment success after job loss: An integrative model and meta-analysis.

    Science.gov (United States)

    Wanberg, Connie R; Kanfer, Ruth; Hamann, Darla J; Zhang, Zhen

    2016-04-01

    Despite widespread popular concern about what it means to be over 40 and unemployed, little attention has been paid in the literature to clarifying the role of age within the job seeking experience. Extending theory, we propose mechanisms by which chronological age affects job search and reemployment outcomes after job loss. Through a meta-analysis and examination of 2 supplemental datasets, we examine 5 questions: (a) How strong is the relationship between age and reemployment speed? (b) Does age disadvantage individuals with respect to other reemployment outcomes? (c) Is the relationship between age and reemployment outcomes mediated by job search activities? (d) Are these relationships generalizable? and (e) Are these relationships linear or curvilinear? Our findings provide evidence for a negative relationship between age and reemployment status and speed across job search decade, world region, and unemployment rate, with the strength of the negative relationship becoming stronger over age 50. Job search self-efficacy and job search intensity partially mediate the relationship between age and both reemployment status and speed. (PsycINFO Database Record PMID:26011790

  18. Research on the Healthy Lifestyle Model, Active Ageing, and Loneliness of Senior Learners

    Science.gov (United States)

    Hung, Jui-Ying; Lu, Kuo-Song

    2014-01-01

    Taiwan has the fastest ageing population in the world. Thus, the government and local policy makers need to formulate policies not just for the nursing and care needs of the aged. They also need to actively promote the need for lifelong learning among seniors in order to achieve elderly-friendly objectives, such as health promotion and delays in…

  19. A Model of Active Ageing through Elder Learning: The Elder Academy Network in Hong Kong

    Science.gov (United States)

    Tam, Maureen

    2013-01-01

    This article presents the Elder Academy (EA) Network as the policy and practice in promoting active ageing through elder learning in Hong Kong. First, the article examines how the change in demographics and the prevalent trend of an ageing population have propelled the government in Hong Kong to tackle issues and challenges brought about by an…

  20. The Leadership Institute for Active Aging: A Volunteer Recruitment and Retention Model.

    Science.gov (United States)

    Wilson, Laura; Steele, Jack; Thompson, Estina; D'heron, Cathy

    2002-01-01

    The Leadership Institute for Active Aging, an approach to recruiting and retaining volunteers over 50, provides training focused on community resources, aging, self-worth, and volunteering and internships in community-based organizations involving health and social services. Exit interviews and program evaluations affirmed that the leadership…

  1. Age-distribution estimation for karst groundwater: Issues of parameterization and complexity in inverse modeling by convolution

    Science.gov (United States)

    Long, A.J.; Putnam, L.D.

    2009-01-01

    Convolution modeling is useful for investigating the temporal distribution of groundwater age based on environmental tracers. The framework of a quasi-transient convolution model that is applicable to two-domain flow in karst aquifers is presented. The model was designed to provide an acceptable level of statistical confidence in parameter estimates when only chlorofluorocarbon (CFC) and tritium (3H) data are available. We show how inverse modeling and uncertainty assessment can be used to constrain model parameterization to a level warranted by available data while allowing major aspects of the flow system to be examined. As an example, the model was applied to water from a pumped well open to the Madison aquifer in central USA with input functions of CFC-11, CFC-12, CFC-113, and 3H, and was calibrated to several samples collected during a 16-year period. A bimodal age distribution was modeled to represent quick and slow flow less than 50 years old. The effects of pumping and hydraulic head on the relative volumetric fractions of these domains were found to be influential factors for transient flow. Quick flow and slow flow were estimated to be distributed mainly within the age ranges of 0-2 and 26-41 years, respectively. The fraction of long-term flow (>50 years) was estimated but was not dateable. The different tracers had different degrees of influence on parameter estimation and uncertainty assessments, where 3H was the most critical, and CFC-113 was least influential.

  2. Simulation of Tritium Transport and Groundwater Age in a Variably Saturated 3D Model, Lake Rotorua Catchment, New Zealand

    Science.gov (United States)

    Daughney, C.; Toews, M. W.; Morgenstern, U.; Cornaton, F. J.; Jackson, B. M.

    2013-12-01

    Lake Rotorua is a focus of culture and tourism in New Zealand. The lake's water quality has declined since the 1970s, partly due to nutrient inputs that reach the lake via the groundwater system. Improved land use management within the catchment requires prediction of the spatial variations of groundwater transit time from land surface to the lake, and from this the prediction of current and future nutrient inflows to the lake. This study combines the two main methods currently available for determination of water age: numerical groundwater models and hydrological tracers. A steady-state 3D finite element model was constructed to simulate groundwater flow and transport of tritium and age at the catchment scale (555 km2). The model materials were defined using a 3D geologic model and included ignimbrites, rhyolites, alluvial and lake bottom sediments. The steady-state saturated groundwater flow model was calibrated using observed groundwater levels in boreholes (111 locations) and stream flow measurements from groundwater-fed streams and springs (61 locations). Hydraulic conductivities and Cauchy boundary conditions associated with the streams, springs and lake were parameterized. The transport parameters for the model were calibrated using 191 tritium samples from 105 locations (springs, streams and boreholes), with most locations having two sample dates. The transport model used steady-state flow, but simulated the transient transport and decay of tritium from rainfall recharge between 1945 and 2012. An additional 1D unsaturated sub-model was added to account for tritium decay from the ground surface to the water table. The sub-model is linked on top of the 3D model, and uses the water table depths and material properties from the 3D model. The adjustable calibration parameters for the transport model were porosity and van Genuchten parameters related to the unsaturated sub-models. Calibration of the flow model was achieved using a combination of automated least

  3. A Novel Approach for Analysis of the Log-Linear Age-Period-Cohort Model: Application to Lung Cancer Incidence

    Directory of Open Access Journals (Sweden)

    Tengiz Mdzinarishvili

    2009-12-01

    Full Text Available A simple, computationally efficient procedure for analyses of the time period and birth cohort effects on the distribution of the age-specific incidence rates of cancers is proposed. Assuming that cohort effects for neighboring cohorts are almost equal and using the Log-Linear Age-Period-Cohort Model, this procedure allows one to evaluate temporal trends and birth cohort variations of any type of cancer without prior knowledge of the hazard function. This procedure was used to estimate the influence of time period and birth cohort effects on the distribution of the age-specific incidence rates of first primary, microscopically confirmed lung cancer (LC cases from the SEER9 database. It was shown that since 1975, the time period effect coefficients for men increase up to 1980 and then decrease until 2004. For women, these coefficients increase from 1975 up to 1990 and then remain nearly constant. The LC birth cohort effect coefficients for men and women increase from the cohort of 1890–94 until the cohort of 1925–29, then decrease until the cohort of 1950–54 and then remain almost unchanged. Overall, LC incidence rates, adjusted by period and cohort effects, increase up to the age of about 72–75, turn over, and then fall after the age of 75–78. The peak of the adjusted rates in men is around the age of 77–78, while in women, it is around the age of 72–73. Therefore, these results suggest that the age distribution of the incidence rates in men and women fall at old ages.

  4. Carbon cycle instability as a cause of the late Pleistocene ice age oscillations - Modeling the asymmetric response

    Science.gov (United States)

    Saltzman, Barry; Maasch, Kirk A.

    1988-01-01

    A dynamical model of the Pleistocene ice ages is presented, which incorporates many of the qualitative ideas advanced recently regarding the possible role of ocean circulation, chemistry, temperature, and productivity in regulating long-term atmospheric carbon dioxide variations. This model involves one additional term (and free parameter) beyond that included in a previous model (Saltzman and Sutera, 1987), providing the capacity for an asymmetric response. It is shown that many of the main features exhibited by the delta(O-18)-derived ice record and the Vostok core/delta(C-13)-derived carbon dioxide record in the late Pleistocene can be deduced as a free oscillatory solution of the model.

  5. Effect of physico-chemical starch properties on bread quality and ageing (model study)

    International Nuclear Information System (INIS)

    fractions during baking as well as by redistribution of water content between those constituents during bread storage. Moreover, it was ascertained, that during ageing redistribution of water content occurs in bread crumb from gluten phase to starch and its migration to crust. A supplement of starch depolymerized by medium doses of gamma irradiation to model pup loaves showed a significant role of dextrins in controlling starch swelling both during baking time and in the process of bread ageing. A partial replacement of wheat flour by large triticale starch granules as well as rye starch depolymerized with gamma irradiation at dose of 3 kGy, decidedly improved the quality of wheat bread and, moreover, caused retardation of crumb hardening process. (author)

  6. A model for net photosynthesis of rose leaves as a function of photosynthetically active radiation, leaf temperature, and leaf age

    International Nuclear Information System (INIS)

    A mathematical description for the relationship between the rate of rose (Rosa hybrida L.) leaf net photosynthesis and photosynthetically active radiation, leaf temperature, and leaf age is developed. The model provides a tool for the prediction of these rates for leaves growing in a rose crop canopy. (author)

  7. Application of IEUBK model in lead risk assessment of children aged 61-84 months old in central China.

    Science.gov (United States)

    Li, Yanyan; Hu, Jia; Wu, Wei; Liu, Shuyun; Li, Mei; Yao, Na; Chen, Jianwei; Ye, Linxiang; Wang, Qi; Zhou, Yikai

    2016-01-15

    Few studies have focused on the accuracy of using the Integrated Exposure Uptake Biokinetic (IEUBK) model in Chinese children with site- and age-specific exposure data. This study aimed to validate the accuracy and sensitivity of the IEUBK model in lead risk assessment of Chinese children aged 61-84 months old. A total of 760 children were enrolled from two respective counties in Central China by using random cluster sampling method. Blood lead levels (BLLs) of all subjects were determined using graphite furnace atomic absorption spectrometry, as well as that in the environmental media, such as air, drinking water, soil, dust and food. Age- and site-specific time-activity patterns and water consumption were evaluated by using questionnaires for children. Exposure parameters including outdoor and indoor activity time, ventilation rate and water consumption in this study were different from the default values of the IEUBK model. Statistical analysis revealed no significant differences between the predicted and observed BLLs. Diet and soil/dust lead intake contributed approximately 83.39% (57.40%-93.84% range) and 15.18% (3.25%-41.60% range) of total lead intake, respectively. These findings showed that the IEUBK model is suitable for lead risk assessment of Chinese children aged 61-84 months old and diet acts as an important lead source. PMID:26433329

  8. Stability and disease persistence in an age-structured SIS epidemic model with vertical transmission and proportionate mixing assumption

    International Nuclear Information System (INIS)

    The stability of the endemic equilibrium of an SIS age-structured epidemic model of a vertically as well as horizontally transmitted disease is investigated when the force of infection is of proportionate mixing assumption type. We also investigate the uniform weak disease persistence. (author)

  9. A random effects population dynamics model based on proportions-at-age and removal data for estimating total mortality

    OpenAIRE

    Trenkel, Verena M.; Bravington, Mark V.; Lorance, Pascal; Walters , Carl

    2012-01-01

    Catch curves are widely used to estimate total mortality for exploited marine populations. The usual population dynamics model assumes constant recruitment across years and constant total mortality. We extend this to include annual recruitment and annual total mortality. Recruitment is treated as an uncorrelated random effect, while total mortality is modelled by a random walk. Data requirements are minimal as only proportions-at-age and total catches are needed. We obtain the effective sampl...

  10. Comparison of empirical and modelled energy performance across age-bands of three-bedroom dwellings in the UK

    OpenAIRE

    Summerfield, A. J.; Oreszczyn, T.; Palmer, J; Hamilton, I. G.; Lowe, R. J.

    2015-01-01

    Differences between measured and predicted energy demand of dwellings across construction age-bands are of interest since these categories mark changes in construction methods and building codes over time. This study compared empirical measures of gas consumption for three-bedroom dwellings in the UK with predictions from the Cambridge Housing Model (CHM), a bottom-up building physics model used for national energy statistics and government policy development. It used gas consumption data col...

  11. Modeling Criminal Careers as Departures from a Unimodal Population Age-Crime Curve: The Case of Marijuana Use

    OpenAIRE

    Telesca, Donatello; Erosheva, Elena A.; Kreager, Derek A.; Ross L. Matsueda

    2012-01-01

    A major aim of longitudinal analyses of life course data is to describe the within- and between-individual variability in a behavioral outcome, such as crime. Statistical analyses of such data typically draw on mixture and mixed-effects growth models. In this work, we present a functional analytic point of view and develop an alternative method that models individual crime trajectories as departures from a population age-crime curve. Drawing on empirical and theoretical claims in criminology,...

  12. Modelling Cost Effectiveness in Neovascular Age-Related Macular Degeneration: The Impact of Using Contrast Sensitivity vs. Visual Acuity.

    OpenAIRE

    Butt, T.; Patel, P. J.; Tufail, A; Rubin, G. S.

    2014-01-01

    Background The cost utility of treatments of age-related macular degeneration (AMD) is commonly assessed using health state transition models defined by levels of visual acuity. However, there is evidence that another measure of visual function, contrast sensitivity, may be better associated with utility than visual acuity. This paper investigates the difference in cost effectiveness resulting from models based on visual acuity and contrast sensitivity using the example of bevacizumab (Avasti...

  13. Tissue-Specific Suppression of Thyroid Hormone Signaling in Various Mouse Models of Aging.

    Directory of Open Access Journals (Sweden)

    W Edward Visser

    Full Text Available DNA damage contributes to the process of aging, as underscored by premature aging syndromes caused by defective DNA repair. Thyroid state changes during aging, but underlying mechanisms remain elusive. Since thyroid hormone (TH is a key regulator of metabolism, changes in TH signaling have widespread effects. Here, we reveal a significant common transcriptomic signature in livers from hypothyroid mice, DNA repair-deficient mice with severe (Csbm/m/Xpa-/- or intermediate (Ercc1-/Δ-7 progeria and naturally aged mice. A strong induction of TH-inactivating deiodinase D3 and decrease of TH-activating D1 activities are observed in Csbm/m/Xpa-/- livers. Similar findings are noticed in Ercc1-/Δ-7, in naturally aged animals and in wild-type mice exposed to a chronic subtoxic dose of DNA-damaging agents. In contrast, TH signaling in muscle, heart and brain appears unaltered. These data show a strong suppression of TH signaling in specific peripheral organs in premature and normal aging, probably lowering metabolism, while other tissues appear to preserve metabolism. D3-mediated TH inactivation is unexpected, given its expression mainly in fetal tissues. Our studies highlight the importance of DNA damage as the underlying mechanism of changes in thyroid state. Tissue-specific regulation of deiodinase activities, ensuring diminished TH signaling, may contribute importantly to the protective metabolic response in aging.

  14. Tissue-Specific Suppression of Thyroid Hormone Signaling in Various Mouse Models of Aging

    Science.gov (United States)

    Visser, W. Edward; Barnhoorn, Sander; Ottaviani, Alexandre; van der Pluijm, Ingrid; Brandt, Renata; Kaptein, Ellen; van Heerebeek, Ramona; van Toor, Hans; Garinis, George A.; Peeters, Robin P.; Medici, Marco; van Ham, Willy; Vermeij, Wilbert P.; de Waard, Monique C.; de Krijger, Ronald R.; Boelen, Anita; Kwakkel, Joan; Kopchick, John J.; List, Edward O.; Melis, Joost P. M.; Darras, Veerle M.; Dollé, Martijn E. T.; van der Horst, Gijsbertus T. J.; Hoeijmakers, Jan H. J.; Visser, Theo J.

    2016-01-01

    DNA damage contributes to the process of aging, as underscored by premature aging syndromes caused by defective DNA repair. Thyroid state changes during aging, but underlying mechanisms remain elusive. Since thyroid hormone (TH) is a key regulator of metabolism, changes in TH signaling have widespread effects. Here, we reveal a significant common transcriptomic signature in livers from hypothyroid mice, DNA repair-deficient mice with severe (Csbm/m/Xpa-/-) or intermediate (Ercc1-/Δ-7) progeria and naturally aged mice. A strong induction of TH-inactivating deiodinase D3 and decrease of TH-activating D1 activities are observed in Csbm/m/Xpa-/- livers. Similar findings are noticed in Ercc1-/Δ-7, in naturally aged animals and in wild-type mice exposed to a chronic subtoxic dose of DNA-damaging agents. In contrast, TH signaling in muscle, heart and brain appears unaltered. These data show a strong suppression of TH signaling in specific peripheral organs in premature and normal aging, probably lowering metabolism, while other tissues appear to preserve metabolism. D3-mediated TH inactivation is unexpected, given its expression mainly in fetal tissues. Our studies highlight the importance of DNA damage as the underlying mechanism of changes in thyroid state. Tissue-specific regulation of deiodinase activities, ensuring diminished TH signaling, may contribute importantly to the protective metabolic response in aging. PMID:26953569

  15. Numerical solute transport modeling for groundwater age determination - An unconventional tracer and its application for aquifer vulnerability assessment

    Science.gov (United States)

    Stollberg, R.; Kiang, C. H.; Weiss, H.

    2013-05-01

    Groundwater management concepts and related vulnerability assessment are highly demanded in water sensitive regions due to general resource scarcity, overexploitation and/or limited groundwater recharge. Within this scope, groundwater age information constitutes essential information for understanding hydraulic dynamics of affected aquifer systems and therefore supports an appropriate groundwater management and protection conceptions, respectively. As the groundwater age or its travel time within large aquifer systems is difficult, time-consuming and costly to determine, conventional solute transport modeling provides a simple and favorable approach for giving a first insight of those spatial patterns. The modeling of groundwater age is based on the classical advective-dispersive formulation for describing and simulating solute transport processes in groundwater. Here, simulation results, being interpreted in terms of groundwater age, constitute a concentration-weighted average time which is describing the pathway from groundwater inflow areas down gradient towards the outflow boundary of the aquifer. Thus, within a closed static system, the groundwater age will continue to increase over time until it reaches steady-state conditions at every location within the flow system. This method was applied successfully to the regional Urucuia aquifer system in Brazil. Here, groundwater residence time patterns are used to understand the hydraulic aquifer dynamics and provide simultaneously information for a respective vulnerability assessment of the limited groundwater resource.

  16. Effects of dimethylaminoethanol and compound amino acid on D-galactose induced skin aging model of rat.

    Science.gov (United States)

    Liu, Su; Chen, Zhenyu; Cai, Xia; Sun, Ying; Zhao, Cailing; Liu, Fangjun; Liu, Dalie

    2014-01-01

    A lasting dream of human beings is to reverse or postpone aging. In this study, dimethylaminoethanol (DMAE) and compound amino acid (AA) in Mesotherapy were investigated for their potential antiaging effects on D-galactose induced aging skin. At 18 days after D-gal induction, each rat was treated with intradermal microinjection of saline, AA, 0.1% DMAE, 0.2% DMAE, 0.1% DMAE + AA, or 0.2% DMAE + AA, respectively. At 42 days after treatment, the skin wound was harvested and assayed. Measurement of epidermal and dermal thickness in 0.1% DMAE + AA and 0.2% DMAE + AA groups appeared significantly thicker than aging control rats. No differences were found in tissue water content among groups. Hydroxyproline in 0.1% DMAE + AA, 0.2% DMAE + AA, and sham control groups was much higher than all other groups. Collagen type I, type III, and MMP-1 expression was highly upregulated in both 0.1% DMAE + AA and 0.2% DMAE + AA groups compared with aging control. In contrast, TIMP-1 expression levels of various aging groups were significantly reduced when compared to sham control. Coinjection of DMAE and AA into target tissue has marked antiaging effects on D-galactose induced skin aging model of rat. PMID:25133239

  17. Analysis of strengthening in AA6111 during the early stages of aging: Atom probe tomography and yield stress modelling

    International Nuclear Information System (INIS)

    In this work, a series of aging treatments has been conducted on AA6111 alloy samples for various times at ambient temperature (so-called natural aging) and at temperatures between 60 and 180 °C (artificially aged). The time at artificial ageing was chosen such that samples with approximately the same yield stress were produced. The microstructures of these alloy samples have been carefully characterized using atom probe tomography together with advanced cluster-finding techniques in order to obtain quantitative information about the changes in distribution of both the solute clusters and early-stage precipitates that are formed. The size distribution of clusters has been mapped onto the glide plane and then the stress necessary for a dislocation to pass through the range of obstacles has been estimated using an areal glide model where the dislocation–obstacle interaction strength has been assumed to be related to the obstacle size on the glide plane. It is demonstrated that the contribution of cluster strengthening during artificial aging at higher temperatures is dominated by the high number density of small clusters (Guinier radius <1 nm), whereas the situation during room temperature natural aging is more complex

  18. Evaluation of unconstrained and constrained mathematical functions to model girth growth of rubber trees (Hevea brasiliensis) using young age measurements

    Institute of Scientific and Technical Information of China (English)

    T. R. Chandrasekhar

    2012-01-01

    No attempt has been made to date to model growth in girth of rubber tree (Hevea brasiliansis).We evaluated the few widely used growth functions to identify the most parsimonious and biologically reasonable model for describing the girth growth of young rubber trees based on an incomplete set of young age measurements.Monthly data for girth of immature trees (age 2 to 12 years) from two locations were subjected to modelling.Re-parameterized,unconstrained and constrained growth functions of Richards (RM),Gompertz (GM) and the monomolecular model (MM) were fitted to data.Duration of growth was the constraint introduced.In the first stage,we attempted a population average (PA) model to capture the trend in growth.The best PA model was fitted as a subject specific (SS) model.We used appropriate error variance-covariance structure to account for correlation due to repeated measurements over time.Unconstrained functions underestimated the asymptotic maximum that did not reflect the carrying capacity of the locations.Underestimations were attributed to the partial set of measurements made during the early growth phase of the trees.MM proved superior to RM and GM.In the random coefficient models,both Gf and G0 appeared to be influenced by tree level effects.Inclusion of diagonal definite positive matrix removed the correlation between random effects.The results were similar at both locations.In the overall assessment MM appeared as the candidate model for studying the girth-age relationships in Hevea trees.Based on the fitted model we conclude that,in Hevea trees,growth rate is maintained at maximum value at t0,then decreases until the final state at dG/dt ≥ 0,resulting in yield curve with no period of accelerating growth.One physiological explanation is that photosynthetic activity in Hevea trees decreases as girth increases and constructive metabolism is larger than destructive metabolism.

  19. Improving bioaerosol exposure assessments 1 - comparative modelling of 2 emissions from different compost ages and activities.

    OpenAIRE

    Taha, M. P. M.; Drew, Gillian H; Tamer Vestlund, Asli; Hewings, G.; Jordinson, G. M.; Longhurst, Philip J.; Pollard, Simon J. T.

    2007-01-01

    We present bioaerosol source term concentrations from passive and active composting sources and compare emissions from green waste compost aged 1, 2, 4, 6, 8, 12 and 16 weeks. Results reveal that the age of compost has little effect on the bioaerosol concentrations emitted for passive windrow sources. However emissions from turning compost during the early stages may be higher than during the later stages of the composting process. The bioaerosol emissions from passive sourc...

  20. Self-assembly of protein aggregates in ageing disorders: the lens and cataract model

    OpenAIRE

    Clark, John I.

    2013-01-01

    Cataract, neurodegenerative disease, macular degeneration and pathologies of ageing are often characterized by the slow progressive destabilization of proteins and their self-assembly to amyloid-like fibrils and aggregates. During normal cell differentiation, protein self-assembly is well established as a dynamic mechanism for cytoskeletal organization. With the increased emphasis on ageing disorders, there is renewed interest in small-molecule regulators of protein self-assembly. Synthetic p...

  1. Antiaging Effect of Inula britannica on Aging Mouse Model Induced by D-Galactose

    OpenAIRE

    Chen, Hui; Long, Yuanyuan; Guo, Lei

    2016-01-01

    The antiaging effect of Inula britannica flower total flavonoids (IBFTF) on aging mice induced by D-galactose and its mechanism was examined in this study. From the results, the biochemical indexes and histological analysis of skin tissues showed that IBFTF could effectively improve the antioxidant enzyme activity of the aging mice, enhance the activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) of skin tissue, and decrease the malondialdehyde (MDA) c...

  2. Lifetime profit modelling of ageing systems utilising information about technical condition

    OpenAIRE

    Thorstensen, Tom Anders

    2008-01-01

    This dissertation focuses on a framework to support decision making in the management of ageing (oil and gas) facilities. Within the oil and gas sector on the Norwegian Continental Shelf the topic has become important as the installations are approaching the end of their intended lifetime. The objective of the thesis is to provide decision support for managing ageing systems and equipment with respect to the inspection, overhaul and replacement strategy in a life cycle perspective. The replac...

  3. Martian ages

    International Nuclear Information System (INIS)

    The subjects of this paper are a discussion of the methodology of relative age determination by impact crater statistics, a comparison of currently proposed Martian impact chronologies for the determination of absolute ages from crater frequencies, a report on our work of dating Martian volcanoes and erosional features by impact crater statistics, and an attempt to understand the main features of Martian history through a synthesis of our crater frequency data and those published by other authors. Two cratering chronology models are presented and used for inference of absolute ages from crater frequency data: model 1, with nearly equal Martian and lunar cratering rates around (ca.) 4- to 10-km crater sizes, and model II. equivalent to model I for ages >3.5 x 109 years but with a factor of 2 higher Martian cratering rate at ages 9 years. Those model cratering chronologies are applied to the data. The interpretation of all crater frequency data available and tractable by our methodology leads to a global Martian geological history that is characterized essentially by two epochs of activity. The division between the two epochs is measured at a cumulative crater frequency value for 1-km craters (crater retention age) of N(1) = 8 x 10-4 (km-2) corresponding to an absolute age of ca. 3 x 109 years (applying model I cratering chronology) and of ca. 1.5 x 109 years (applying model II cratering chronology). In the ancient epoch all major events like emplacement of the plains lavas, the piling up of most volcanic constructs, and large-scale erosion of channels and mensae (highland/northern lowland boundary) have taken place. During the younger epoch, only the big Tharsis shield volcanoes were active, and some minor erosion took place. This means that Mars is not a youthful planet but an ancient one with respect to most of its surface features

  4. Groundwater age and lifetime expectancy modelling approach for site characterization and performance assessment of radwaste repository in clay formation

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. A deep geological repository of high level and long lived radwaste requires an understanding of the far field and near field groundwater flow and of the transport properties, at actual and future climatic conditions. Andra, French National radioactive waste management Agency, is developing since last 15 years an integrated multi-scale hydrogeological model of whole Paris basin of 200000 km2 of area (regional scale) to produce a regional flow field associated to groundwater behavior. It includes locally the Meuse/Haute Marne clay site of about 250 km2 of area in the eastern part of the Paris basin that was chosen for the emplacement of a repository. The Callovo-Oxfordian host formation is a clay layer characterized by a very low permeability of the order 10-14 m/s, a mean thickness of 130 m at about 500 m depth, and is embedded by calcareous aquifer formations (Dogger and Oxfordian). The hydrogeological conceptual model is based on stratigraphic and petro-physic modeling of the Paris basin and is accounting for the structural, geological, hydrogeological and geochemical data in an integrated way. This model represents 27 hydrogeological units at the scale of the Paris Basin, and it is refined at the scale of the sector to represent 27 different layers that range in age from the Trias to the Portlandian. The finite element flow and transport simulator Ground Water (GW) is used to solve for groundwater flow at steady-state in a 3 Million elements model, considering current climatic conditions. The model is calibrated against about 1250 hydraulic head measurements, and results in maximum absolute hydraulic head differences of 20 meters at the regional scale and 3 meters at the local scale. The calibrated reference model includes transmissive major faults as well as structures acting as barrier to flow. Groundwater age (the time elapsed since recharge) and lifetime expectancy (the time remaining prior to exit) are

  5. Mass accumulation rate and monsoon records from Xifeng, Chinese Loess Plateau, based on a luminescence age model

    DEFF Research Database (Denmark)

    Stevens, Thomas; Buylaert, Jan-Pieter; Lu, Huayu;

    2016-01-01

    Luminescence dating of loess accumulation in China has raised questions over disturbance and gaps in the record, the magnitude of mass accumulation rates (MARs), and monsoon forcing mechanisms. Here we present a detailed quartz optically stimulated luminescence (OSL) chronology from the Xifeng...... Chinese Loess Plateau site. We reconstruct MARs and construct an age model for monsoon proxies at the site. The luminescence ages show significant pedogenic and anthropogenic disturbance in material deposited after ca. 20–22 ka. Analysis of other published data suggests that this disturbance may be more...

  6. Tracer kinetics: Modelling by partial differential equations of inhomogeneous compartments with age-dependent elimination rates. Pt. 1

    International Nuclear Information System (INIS)

    Mathematical models in tracer kinetics are usually based on ordinary differential equations which correspond to a system of kinetically homogeneous compartments (standard compartments). A generalization is possible by the admission of inhomogeneities in the behaviour of the elements belonging to a compartment. The important special case of the age-dependence of elimination rates is treated in its deterministic version. It leads to partial different equations (i.e., systems with distributed coefficients) with the 'age' or the 'residence time' of an element of the compartment as a variable additional to 'time'. The basic equations for one generalized compartment and for systems of such compartments are given together with their general solutions. (orig.)

  7. Prediction model for adult height of small for gestational age children at the start of growth hormone treatment

    OpenAIRE

    Ridder, Maria; Stijnen, Theo; Hokken-Koelega, Anita

    2008-01-01

    textabstractContext: GH treatment is approved for short children born small for gestational age (SGA). The optimal dose is not yet established. Objective: Our objective was to develop a model for prediction of height at the onset of puberty and of adult height (AH). Design and Setting: Two GH studies were performed in short SGA children. Patients/Intervention: A total of 150 SGA children with height SD scores (SDS) less than -2, age 3 yr or older, no signs of catch-up growth, available height...

  8. Functional Time Series Models to Estimate Future Age-Specific Breast Cancer Incidence Rates for Women in Karachi, Pakistan

    Institute of Scientific and Technical Information of China (English)

    Farah Yasmeen[1; Sidra Zaheer[2

    2014-01-01

    Background: Breast cancer is the most common female cancer in Pakistan. The incidence of breast cancer in Pakistan is about 2.5 times higher than that in the neighboring countries India and Iran. In Karachi, the most populated city of Pakistan, the age-standardized rate of breast cancer was 69.1 per 100,000 women during 1998-2002, which is the highest recorded rate in Asia. The carcinoma of breast in Pakistan is an enormous public health concern. In this study, we examined the recent trends of breast cancer incidence rates among the women in Karachi. Methods: We obtained the secondary data of breast cancer incidence from various hospitals. They included Jinnah Hospital, KIRAN (Karachi Institute of Radiotherapy and Nuclear Medicine), and Civil hospital, where the data were available for the years 2004-2011. A total of 5331 new cases of female breast cancer were registered during this period. We analyzed the data in 5-year age groups 15-19, 20-24, 25-29, 30-34, 35-39, 40-44, 45-49, 50-54, 55-59, 60-64, 65-69, 70-74, 75+. Nonparametric smoothing were used to obtained age-specific incidence curves, and then the curves are decomposed using principal components analysis to fit FTS (functional time series) model. We then used exponential smoothing statspace models to estimate the forecasts of incidence curve and construct prediction intervals. Results: The breast cancer incidence rates in Karachi increased with age for all available years. The rates increased monotonically and are relatively sharp with the age from 15 years to 50 years and then they show variability after the age of 50 years. 10-year forecasts for the female breast cancer incidence rates in Karachi show that the future rates are expected to remain stable for the age-groups 15-50 years, but they will increase for the females of 50-years and over. Hence in future, the newly diagnosed breast cancer cases in the older women in Karachi are expected to increase. Conclusion: Prediction of age

  9. EXTINCTION AND WAVEFRONT IN AN AGE-STRUCTURED POPULATION MODEL ON INFINITE PATCHES WITH DISTRIBUTED MATURATION DELAY

    Institute of Scientific and Technical Information of China (English)

    LING Jiaoxiu; WENG Peixuan

    2005-01-01

    In this paper, we derive a lattice model for a single species on infinite patches of one-dimensional space with that the maturation could occur at any age. The formulation involves a distribution of possible ages of maturation and a probability density function on which ecological assumptions are made. The following results are obtained: the existence and isotropy of the unique nonnegative solution for initial value problem, the extinction of the species provided with the non-existence of positive equilibria, and the existence of wavefronts with the wave speed c > c*.

  10. Evaluation of alternative age-based methods for estimating relative abundance from survey data in relation to assessment models

    DEFF Research Database (Denmark)

    Berg, Casper Willestofte; Nielsen, Anders; Kristensen, Kasper

    2014-01-01

    Indices of abundance from fishery-independent trawl surveys constitute an important source of information for many fish stock assessments. Indices are often calculated using area stratified sample means on age-disaggregated data, and finally treated in stock assessment models as independent...... observations. We evaluate a series of alternative methods for calculating indices of abundance from trawl survey data (delta-lognormal, delta-gamma, and Tweedie using Generalized Additive Models) as well as different error structures for these indices when used as input in an age-based stock assessment model...... different indices produced. The stratified mean method is found much more imprecise than the alternatives based on GAMs, which are found to be similar. Having time-varying index variances is found to be of minor importance, whereas the independence assumption is not only violated but has significant impact...

  11. Stream water age distributions controlled by storage dynamics and nonlinear hydrologic connectivity: Modeling with high-resolution isotope data

    Science.gov (United States)

    Soulsby, C.; Birkel, C.; Geris, J.; Dick, J.; Tunaley, C.; Tetzlaff, D.

    2015-09-01

    To assess the influence of storage dynamics and nonlinearities in hydrological connectivity on time-variant stream water ages, we used a new long-term record of daily isotope measurements in precipitation and streamflow to calibrate and test a parsimonious tracer-aided runoff model. This can track tracers and the ages of water fluxes through and between conceptual stores in steeper hillslopes, dynamically saturated riparian peatlands, and deeper groundwater; these represent the main landscape units involved in runoff generation. Storage volumes are largest in groundwater and on the hillslopes, though most dynamic mixing occurs in the smaller stores in riparian peat. Both streamflow and isotope variations are generally well captured by the model, and the simulated storage and tracer dynamics in the main landscape units are consistent with independent measurements. The model predicts that the average age of stream water is ˜1.8 years. On a daily basis, this varies between ˜1 month in storm events, when younger waters draining the hillslope and riparian peatland dominates, to around 4 years in dry periods when groundwater sustains flow. This variability reflects the integration of differently aged water fluxes from the main landscape units and their mixing in riparian wetlands. The connectivity between these spatial units varies in a nonlinear way with storage that depends upon precipitation characteristics and antecedent conditions. This, in turn, determines the spatial distribution of flow paths and the integration of their contrasting nonstationary ages. This approach is well suited for constraining process-based modeling in a range of northern temperate and boreal environments.

  12. An Age-Dependent Physiologically-Based Pharmacokinetic/Pharmacodynamic Model for the Organophosphorus Insecticide Chlorpyrifos in the Preweanling Rat

    Energy Technology Data Exchange (ETDEWEB)

    Timchalk, Chuck; Kousba, Ahmed A.; Poet, Torka S.

    2007-08-01

    Juvenile rats are more susceptible than adults to the acute toxicity of organophosphorus insecticides like chlorpyrifos (CPF). Age- and dose-dependent differences in metabolism may be responsible. Of importance is CYP450 activation and detoxification of CPF to chlorpyrifos-oxon (CPF-oxon) and trichloropyridinol (TCP), as well as B-esterase (cholinesterase; ChE) and A-esterase (PON-1) detoxification of CPF-oxon to TCP. In the current study, a modified physiologically based pharmacokinetic/pharmacodynamic (PBPK/PD) model incorporating age-dependent changes in CYP450, PON-1, and tissue ChE levels for rats was developed. In this model, age was used as a dependent function to estimate body weight which was then used to allometrically scale both metabolism and tissue ChE levels. Model simulations suggest that preweanling rats are particularly sensitive to CPF toxicity, with levels of CPF-oxon in blood and brain disproportionately increasing, relative to the response in adult rats. This age-dependent non-linear increase in CPF-oxon concentration may potentially result from the depletion of non-target B-esterases, and a lower PON-1 metabolic capacity in younger animals. These results indicate that the PBPK/PD model behaves consistently with the general understanding of CPF toxicity, pharmacokinetics and tissue ChE inhibition in neonatal and adult rats. Hence, this model represents an important starting point for developing a computational model to assess the neurotoxic potential of environmentally relevant organophosphate exposures in infants and children.

  13. Regional models of metal production in Western Asia in the Chalcolithic, Early and Middle Bronze Ages

    Directory of Open Access Journals (Sweden)

    Avilova, Liudmila

    2008-06-01

    Full Text Available The objective of this work is the reconstruction and comparative analysis of regional models of metal production in the Chalcolithic, Early and Middle Bronze Ages. The work is based on the statistical analysis of unique computer database on archaeological metal finds from four regions of the Near East: Anatolia, Mesopotamia, the Levant, and Iran. The materials are analysed by four indicators: distribution by the chronological periods, artefacts’ function, proportion of used metals and copper- based alloys. The author presents a series of conclusions concerning the preconditions for the beginnings of metal production in Western Asia and the pioneering role of Iran in its emergence, the important role the piedmont territories played in the development of metal production, the leap-like pattern of production dynamics shown by the periods, and its relation to the spread of a producing economy, long-distance exchange, and the emergence of the early civilizations.

    El objetivo de este trabajo es la reconstrucción y análisis comparativo de modelos regionales de producción metalúrgica del Calcolítico y la Edad del Bronce Inicial y Media. Se basa en el análisis estadístico de una base de datos única sobre hallazgos metálicos de cuatro regiones del Próximo Oriente: Anatolia, Mesopotamia, el Levante e Irán. Los materiales se analizan atendiendo a cuatro variables: períodos cronológicos, función de los artefactos, proporción de los metales usados y las distintas aleaciones del cobre. La autora aporta una serie de conclusiones respecto a las precondiciones para los inicios de la producción metalúrgica en el Oeste Asiático; sobre el papel pionero de Irán en su aparición; la importancia de los piedemontes en su desarrollo; el patrón no continuo que se observa en las dinámicas de producción por periodos; y su relación con la expansión de la economía de producción, el intercambio a larga distancia y la aparición de las

  14. Hydrochemical modelling and determination of 14C ages of geothermal waters in Kizildere and Tekkehamam fields

    International Nuclear Information System (INIS)

    Many geothermal fluids are encountered as springs and wells in the area between Buharkent - Yenice - Pamukkale located in the Aegean Region to the east of the Bueyuek Menderes Graben. This study, constituting a part of the project called 'Age and Origin Determination of the High Temperature Geothermal Fluids in the Bueyuek Menderes Graben' and directed by the MTA General Directorate, aims the recharge and circulation period verification of related resources by means of interpreting isotopic and hydrochemical data of the above mentioned region. For this purpose, water chemistry, δ18O, δ2H, δ3H, 14C, δ34S-SO4 ve δ18O-SO4 isotope sampling have been realized in order to determine the geochemical processes taken place in underground. As a result of the study the origin, the recharge altitudes and the circulation periods of grouped fluids with temperatures between 35 degrees- 242 degreeslocated in the region were clarified. According to the given chemical data, hydrochemically characterized waters are classified in 10 different types. It has been indicated that, six subtypes of the classification are constituted from the mixtures of waters at 242 degreesand 4th type Na-HCO3 belonging to Kizildere thermal waters, first type Ca-HCO3 waters, second type Ca-HCO3-SO4 waters and third type Ca-SO4 waters. According to the evaluation of the 14C isotope, the geothermal fluid discharging from the Kizildere Power Plant, corresponds to a turnovertime of 22.500 - 27.500 years. Previous studies reveal that the waters of the Tekkehamam geothermal field originate from the mixture of shallow groundwaters encountered in the site with geothermal fluids underflowing from the Kizildere geothermal field, in north-south direction. Taken into consideration this mentioned mixture model, the 14C isotope indicates a turnovertime of 31.000 years for R-1 geothermal well and 35.000 years for the нnatlм spring, located in the Tekkehamam geothermal field

  15. Incubation periods under various anti-retroviral therapies in homogeneous mixing and age-structured dynamical models: A theoretical approach

    CERN Document Server

    Rao, Arni S R Srinivasa

    2008-01-01

    Abstract. We consider previously well-known models in epidemiology where the parameter for incubation period is used as one of the important components to explain the dynamics of the variables. Such models are extended here to explain the dynamics with respect to a given therapy that prolongs the incubation period. A deconvolution method is demonstrated for estimation of parameters in the situations when no-therapy and multiple therapies are given to the infected population. The models and deconvolution method are extended in order to study the impact of therapy in age-structured populations. A generalisation for a situation when n-types of therapies are available is given.

  16. Multi-mutational model for cancer based on age-time patterns of radiation effects: 2. Biological aspects

    Energy Technology Data Exchange (ETDEWEB)

    Mendelsohn, M.L.; Pierce, P.A.

    1997-09-04

    Biological properties of relevance when modeling cancers induced in the atom bomb survivors include the wide distribution of the induced cancers across all organs, their biological indistinguishability from background cancers, their rates being proportional to background cancer rates, their rates steadily increasing over at least 50 years as the survivors age, and their radiation dose response being linear. We have successfully described this array of properties with a modified Armitage-Doll model using 5 to 6 somatic mutations, no intermediate growth, and the dose-related replacement of any one of these time-driven mutations by a radiation-induced mutation. Such a model is contrasted to prevailing models that use fewer mutations combined with intervening growth. While the rationale and effectiveness of our model is compelling for carcinogenesis in the atom bomb survivors, the lack of a promotional component may limit the generality of the model for other types of human carcinogenesis.

  17. Automated evolutionary optimization of ion channel conductances and kinetics in models of young and aged rhesus monkey pyramidal neurons.

    Science.gov (United States)

    Rumbell, Timothy H; Draguljić, Danel; Yadav, Aniruddha; Hof, Patrick R; Luebke, Jennifer I; Weaver, Christina M

    2016-08-01

    Conductance-based compartment modeling requires tuning of many parameters to fit the neuron model to target electrophysiological data. Automated parameter optimization via evolutionary algorithms (EAs) is a common approach to accomplish this task, using error functions to quantify differences between model and target. We present a three-stage EA optimization protocol for tuning ion channel conductances and kinetics in a generic neuron model with minimal manual intervention. We use the technique of Latin hypercube sampling in a new way, to choose weights for error functions automatically so that each function influences the parameter search to a similar degree. This protocol requires no specialized physiological data collection and is applicable to commonly-collected current clamp data and either single- or multi-objective optimization. We applied the protocol to two representative pyramidal neurons from layer 3 of the prefrontal cortex of rhesus monkeys, in which action potential firing rates are significantly higher in aged compared to young animals. Using an idealized dendritic topology and models with either 4 or 8 ion channels (10 or 23 free parameters respectively), we produced populations of parameter combinations fitting the target datasets in less than 80 hours of optimization each. Passive parameter differences between young and aged models were consistent with our prior results using simpler models and hand tuning. We analyzed parameter values among fits to a single neuron to facilitate refinement of the underlying model, and across fits to multiple neurons to show how our protocol will lead to predictions of parameter differences with aging in these neurons. PMID:27106692

  18. The ecological stress theory of aging and hormesis: an energetic evolutionary model.

    Science.gov (United States)

    Parsons, Peter A

    2007-06-01

    Free-living organisms normally struggle to exist in harsh environments that are nutritionally and energetically inadequate, where evolutionary adaptation is challenged by internal stresses within organisms and external stresses from the environment. The incorporation of environmental variables into aging theories such as the free-radical and metabolic rate/oxidative stress theories, is the basis of the ecological stress theory of aging and hormesis. Environmental variation from optimum to lethal extremes gives a fitness-stress continuum, where energetic efficiency, or fitness, is inversely related to stress level; in the evolutionary context survival is a more direct measure of fitness for assessing aging than is lifespan. On this continuum, the hormetic zone is in the optimum region, while aging emphasizes survival towards lethal extremes. At the limits of survival, a convergence of physiological and genetical processes is expected under accumulating stress from Reactive Oxygen Species, ROS. Limited ecologically-oriented studies imply that major genes are important towards limits of survival compared with the hormetic zone. Future investigations could usefully explore outlier populations physiologically and genetically, since there is the likelihood that genetic variability may be lower in those cohorts managing to survive to extremely advanced ages as found in highly stressed ecological outlier populations. If so, an evolutionary explanation of the mortality-rate decline typical of cohorts of the extremely old emerges. In summary, an energetic evolutionary approach produces a general aging theory which automatically incorporates hormesis, since the theory is based on a fitness-stress continuum covering the whole range of possible abiotic environments of natural populations. PMID:17473992

  19. Ageing management

    International Nuclear Information System (INIS)

    Ageing management is generally defined in a broad sense covering not only ageing management of hardware (structures, systems and components), but also management issues such as keeping up with developments in state-of-the-art technology and the latest management practices. The importance assigned to traditional ageing management, in terms of issues related to hardware degradation problems, is clearly very high. The other aspects, for example developments in engineering or management, are considered important as well, but are less emphasized. Plant ageing management is composed of the following necessary elements, which are all linked together: understanding and knowledge of ageing-related damage mechanisms, including benchmarking of the consequences of damage mechanisms into macroscopic behaviour of materials and structures under applicable conditions; predictive models to extrapolate behaviour of systems, structures or components up to a defined time; qualified methods for detection and surveillance of ageing degradation; qualified mitigation, repair and replacements measures; reliable plant documentation, including optimisation of the ageing management programme based on current understanding and knowledge and periodic self-assessment; availability of a technical service and knowledge base. The subject of plant ageing management has gained increasing attention over the past years, notably as more nuclear power plants across the world are being considered for lifetime extension. In this context, the NEA has conducted numerous technical studies to assess the impact of ageing mechanisms on safe and reliable plant operation. International research activities have also been initiated or are under way to provide the technical basis for decision making. This article provides an overview of some of the activities and accomplishments of the NEA Committee on the Safety of Nuclear Installations (CSNI) Working Group on the Integrity and Ageing of Components and Structures

  20. Modeling age and growth of the bigeye thresher (Alopias superciliosus) in the Atlantic Ocean

    OpenAIRE

    Fernandez-Carvalho, Joana; Coelho, R.; Erzini, Karim; Miguel N. Santos

    2015-01-01

    The bigeye thresher (Alopias superciliosus) is a pelagic shark captured as bycatch in pelagic longline fisheries. Important information on its biology is still missing, especially from the Atlantic Ocean. In all, 546 vertebrae collected by fishery observers between 2007 and 2009 were used to estimate age and growth parameters for this species in the Atlantic Ocean. The size composition was 102–265 cm fork length (FL) for females and 94–260 cm FL for males. The estimated ages ranged from 0 to ...

  1. PRODUCTION OF CROSS-REACTIVE AUTOANTIBODY BINDING TO BOVINE SERUM ALBUMIN IN THE D-GALACTOSE-INDUCED AGING MOUSE MODEL

    Directory of Open Access Journals (Sweden)

    Ji-Hun Park

    2014-01-01

    Full Text Available The D-galactose (D-gal-induced animal model, generated by repeated subcutaneous D-gal injections over approximately 6 weeks, has been frequently used for diabetes and aging research. However, little research has investigated the direct correlation between D-gal and autoantibody formation despite several reports on diabetes-and aging-related autoantibodies. The purpose of this study was to determine whether repetitive injection of D-gal can induce autoantibody production in mice. First, we used Bovine Serum Albumin (BSA and Advanced Glycation End products (AGE-BSA as the test antigens. The immunoreactivity of serum samples from mice treated with D-gal for 6 weeks was evaluated using Enzyme-Linked Immunosorbent Assay (ELISA. We found that serum samples of D-gal-treated mice had significantly high antibody titers against both BSA and AGE-BSA. Furthermore, the result showed that aminoguanidine treatment, an AGE inhibitor tended to decrease this immunoreactivity. The results of competitive inhibition ELISA using BSA and AGE-BSA as the competitors suggested that the serum samples from D-gal-treated mice contained antibodies not only against BSA but also specific to AGE-BSA. To assess whether the immunoreactivity against BSA is comparable to that against Mouse Serum Albumin (MSA, we examined the reactivity of D-gal-induced antibodies against MSA. Unexpectedly, D-gal-induced antibodies did not react with MSA. This suggests that the production of antibodies by D-gal is in response to an unknown antigen(s, aside from MSA, in mice and that this unknown antigen(s may share similar sequences or three-dimensional structures with BSA.

  2. Evidence for cervical cancer mortality with screening program in Taiwan, 1981–2010: age-period-cohort model

    Directory of Open Access Journals (Sweden)

    Su Shih-Yung

    2013-01-01

    Full Text Available Abstract Background Cervical cancer is the most common cancer experienced by women worldwide; however, screening techniques are very effective for reducing the risk of death. The national cervical cancer screening program was implemented in Taiwan in 1995. The objective of this study was to examine and provide evidence of the cervical cancer mortality trends for the periods before and after the screening program was implemented. Methods Data from 1981 to 2010 of the causes of death registered were obtained from the Department of Health, Taiwan. Age-standardized mortality rates, age-specific rates, and age-period-cohort models that employed the sequential method were used to assess temporal changes that occurred between 1981 and 2010, with 1995 used as the separating year. Results The results showed that for both time periods of 1981 to 1995 and 1996 to 2010, age and period had significant effects, whereas the birth cohort effects were insignificant. For patients between 80 and 84 years of age, the mortality rate for 1981 to 1995 and 1996 to 2010 was 48.34 and 68.08. The cervical cancer mortality rate for 1996 to 2010 was 1.0 for patients between 75 and 79 years of age and 1.4 for patients between 80 and 84 years of age compared to that for 1981 to 1995. Regarding the period effect, the mortality trend decreased 2-fold from 1996 to 2010. Conclusions The results of this study indicate a decline in cervical cancer mortality trends after the screening program involving Papanicolaou tests was implemented in 1995. However, the positive effects of the screening program were not observed in elderly women because of treatment delays during the initial implementation of the screening program.

  3. A micro-continuum-mechanical material model for failure of rubber-like materials: Application to ageing-induced fracturing

    Science.gov (United States)

    Dal, Hüsnü; Kaliske, Michael

    2009-08-01

    Rubbery polymers are subjected to severe environmental conditions under service. As a consequence of various ageing mechanisms, the outer surface of rubber components hardens in time and cracking occurs as a result of combined mechanical and chemical processes. Conventional phenomenological hyperelastic constitutive models do not account for material softening. Consequently, the stored energy and stresses tend to infinity as stretch increases. In this contribution, a network alteration for the ageing mechanism of rubber-like materials is introduced along with a micromolecular description of material failure. The proposed micro-continuum material model is based on a serial construction of a Langevin-type spring representing the energy storage owing to conformational changes induced by deformation, to a bond potential representing the energy stored in the polymer chain due to the interatomic displacement. For the representation of the micro-macro transition, the non-affine kinematics of the micro-sphere model is used. The Morse potential is utilized for the interatomic bond, which describes the energetic contribution to rubber-like materials and governs the failure of the polymer chain in terms of bond rupture. A novel numerical scheme for the FE implementation of the proposed model is demonstrated. The hardening phenomenon as a result of diffusion limited oxidation of rubber is explained by the principle of mass conservation which dictates simultaneous modulus hardening along with decrease in ultimate stretch observed in aged rubbery polymers.

  4. Advancing paternal age is associated with deficits in social and exploratory behaviors in the offspring: a mouse model.

    Directory of Open Access Journals (Sweden)

    Rebecca G Smith

    Full Text Available BACKGROUND: Accumulating evidence from epidemiological research has demonstrated an association between advanced paternal age and risk for several psychiatric disorders including autism, schizophrenia and early-onset bipolar disorder. In order to establish causality, this study used an animal model to investigate the effects of advanced paternal age on behavioural deficits in the offspring. METHODS: C57BL/6J offspring (n = 12 per group were bred from fathers of two different ages, 2 months (young and 10 months (old, and mothers aged 2 months (n = 6 breeding pairs per group. Social and exploratory behaviors were examined in the offspring. PRINCIPAL FINDINGS: The offspring of older fathers were found to engage in significantly less social (p = 0.02 and exploratory (p = 0.02 behaviors than the offspring of younger fathers. There were no significant differences in measures of motor activity. CONCLUSIONS: Given the well-controlled nature of this study, this provides the strongest evidence for deleterious effects of advancing paternal age on social and exploratory behavior. De-novo chromosomal changes and/or inherited epigenetic changes are the most plausible explanatory factors.

  5. Joint Modelling of Survival and Emergency Medical Care Usage in Spanish Insureds Aged 65+

    OpenAIRE

    Piulachs Lozada-Benavente, Xavier; Alemany Leira, Ramon; Guillén, Montserrat

    2016-01-01

    We study the longevity and medical resource usage of a large sample of insureds aged 65 years or older drawn from a large health insurance dataset. Yearly counts of each subject's emergency room and ambulance service use and hospital admissions are made. Occurrence of mortality is also monitored. The study aims to capture the simultaneous dependence between their demand for healthcare and survival.

  6. Self-assembly of protein aggregates in ageing disorders: the lens and cataract model.

    Science.gov (United States)

    Clark, John I

    2013-05-01

    Cataract, neurodegenerative disease, macular degeneration and pathologies of ageing are often characterized by the slow progressive destabilization of proteins and their self-assembly to amyloid-like fibrils and aggregates. During normal cell differentiation, protein self-assembly is well established as a dynamic mechanism for cytoskeletal organization. With the increased emphasis on ageing disorders, there is renewed interest in small-molecule regulators of protein self-assembly. Synthetic peptides, mini-chaperones, aptamers, ATP and pantethine reportedly regulate self-assembly mechanisms involving small stress proteins, represented by human αB-crystallin, and their targets. Small molecules are being considered for direct application as molecular therapeutics to protect against amyloid and protein aggregation disorders in ageing cells and tissues in vivo. The identification of specific interactive peptide sites for effective regulation of protein self-assembly is underway using conventional and innovative technologies. The quantification of the functional interactions between small stress proteins and their targets in vivo remains a top research priority. The quantitative parameters controlling protein-protein interactions in vivo need characterization to understand the fundamental biology of self-assembling systems in normal cells and disorders of ageing. PMID:23530262

  7. Intensive woodland management in the Middle Ages: spatial modelling based on archival data

    Czech Academy of Sciences Publication Activity Database

    Szabó, Péter; Müllerová, Jana; Suchánková, Silvie; Kotačka, Martin

    2015-01-01

    Roč. 48, April 2015 (2015), s. 1-10. ISSN 0305-7488 EU Projects: European Commission(XE) 278065 - LONGWOOD Institutional support: RVO:67985939 Keywords : coppice * Moravia * Middle Ages Subject RIV: EF - Botanics Impact factor: 1.028, year: 2014

  8. A simple application of probability model for the mean age at marriage

    International Nuclear Information System (INIS)

    An attempt has been made in this paper to examine the age pattern of marriage among Nepalese women. A lognormal distribution has been used and applied to the data from Nepal Fertility Survey (1986). The estimation procedure has been carried out by using method of moments and maximum likelihood method. (author). 6 refs, 1 tab

  9. Social Security Reform and Population Ageing in a Two-Sector Growth Model

    NARCIS (Netherlands)

    van Groezen, B.J.A.M.; Meijdam, A.C.; Verbon, H.A.A.

    2002-01-01

    This paper analyses the effects of reducing unfunded social security and population ageing on economic growth and welfare, both for a small open economy and for a closed economy.The economy consists of a service sector and a commodity sector.Productivity growth only occurs in the latter sector and i

  10. Toward a Testable Developmental Model of Pedophilia: The Development of Erotic Age Preference.

    Science.gov (United States)

    Freund, Kurt; Kuban, Michael

    1993-01-01

    Analysis of retrospective self-reports about childhood curiosity to see persons in the nude, with heterosexual and homosexual pedophiles, gynephiles, and androphiles, suggests that establishment of erotic sex preference proceeded that of age preference, and a greater proportion of pedophiles than gynephiles or androphiles remembered childhood…

  11. Asphalt Pavement Aging and Temperature Dependent Properties Using Functionally Graded Viscoelastic Model

    Science.gov (United States)

    Dave, Eshan V.

    2009-01-01

    Asphalt concrete pavements are inherently graded viscoelastic structures. Oxidative aging of asphalt binder and temperature cycling due to climatic conditions being the major cause of non-homogeneity. Current pavement analysis and simulation procedures dwell on the use of layered approach to account for these non-homogeneities. The conventional…

  12. Excessive folate synthesis limits lifespan in the C. elegans: E. coli aging model

    Directory of Open Access Journals (Sweden)

    Virk Bhupinder

    2012-07-01

    Full Text Available Abstract Background Gut microbes influence animal health and thus, are potential targets for interventions that slow aging. Live E. coli provides the nematode worm Caenorhabditis elegans with vital micronutrients, such as folates that cannot be synthesized by animals. However, the microbe also limits C. elegans lifespan. Understanding these interactions may shed light on how intestinal microbes influence mammalian aging. Results Serendipitously, we isolated an E. coli mutant that slows C. elegans aging. We identified the disrupted gene to be aroD, which is required to synthesize aromatic compounds in the microbe. Adding back aromatic compounds to the media revealed that the increased C. elegans lifespan was caused by decreased availability of para-aminobenzoic acid, a precursor to folate. Consistent with this result, inhibition of folate synthesis by sulfamethoxazole, a sulfonamide, led to a dose-dependent increase in C. elegans lifespan. As expected, these treatments caused a decrease in bacterial and worm folate levels, as measured by mass spectrometry of intact folates. The folate cycle is essential for cellular biosynthesis. However, bacterial proliferation and C. elegans growth and reproduction were unaffected under the conditions that increased lifespan. Conclusions In this animal:microbe system, folates are in excess of that required for biosynthesis. This study suggests that microbial folate synthesis is a pharmacologically accessible target to slow animal aging without detrimental effects.

  13. Strengths for mastering ageing by realizing tools in Europe: Senior learning model

    NARCIS (Netherlands)

    de Greef, M.; de Donder, L.; Kardol, T.; Segers, M.S.R.; Verté, D.

    2014-01-01

    During the European year of "Active Ageing" the European Commission aims to stimulate increase of social inclusion of older people. According to Nilsson (2010) education can be an effective intervention to increase social inclusion. In order to assess the impact of adult education on social inclusio

  14. Modeling of immunological ageing with radiation and its modulation by an herbal composition hemohim

    International Nuclear Information System (INIS)

    Although aging is one of the several chronic effects of ionizing radiation (IR), there have been no experimental data on radiation-induced immunological aging. The most interesting aging-related change in immune system is the imbalance of helper T (Th) 1- and Th2-related immune responses that are associated with many diseases. We investigated chronic effects on immune responses after IR exposure (5Gy) in mice in comparison with those of old mice. At 6 months after irradiation, the proliferation of spleen lymphocytes which was known as the most important issue in an aging process was declined similarly to that of 18-months-old mice. IFN-a-bar and IgG2a levels (Th1-related response) were lower in irradiated mice than in normal mice of same age, showing similar levels to those of old normal mice. In contrast, IL-4, IL-5, IgG1 and IgE levels (Th2-related response) were increased in irradiated mice when compared with the same-aged normal mice. Also, the low expression of IL-12p70 and its receptors in irradiated and old mice was detected. The level of phosphorylated STAT4 was lower in the irradiated mice. In addition, the decrease of NK cell activity was intensified in the irradiated mice, showing lower values than those of old mice. Interestingly, the absolute numbers and the percentages of NK cells was extremely decreased in irradiated mice, whereas the absolute numbers of Th cells and Tc cells were significantly decreased in old mice. Taken together, however, our results showed that 8-month-old irradiated mice exhibited immunological changes similar to 18-month-old normal mice and it can be suggested that IR can induce the rapid immunological aging. In our lab, HemoHIM, a new herbal composition, had been previously developed to protect the self-renewal tissues and promote the recovery of immune system against acute IR. Our recent data showed that HemoHIM can ameliorate the immunological imbalance that persisted long-term in fractionated-IR exposed mice by regulating

  15. COMPARISON OF THE EFFECTS OF AGING AND IL-6 ON THE HEPATIC INFLAMMATORY RESPONSE IN TWO MODELS OF SYSTEMIC INJURY: SCALD INJURY VERSUS I.P. LPS ADMINISTRATION

    OpenAIRE

    Gomez, Christian R.; Nomellini, Vanessa; Baila, Horea; Oshima, Kiyoko; Kovacs, Elizabeth J.

    2009-01-01

    Regardless of age, a marked elevation in circulating IL-6 levels correlates with increased mortality after injury or an inflammatory challenge. We previously reported that aged IL-6 knockout mice given LPS have improved survival and reduced inflammatory response than LPS-treated aged wild type (WT) mice. Herein, we analyzed the effects of aging and IL-6 on the hepatic inflammatory response in two models of systemic injury: dorsal scald (burn) injury versus intraperitoneal LPS administration. ...

  16. A Method Based on Active Appearance Model and Gradient Orientation Pyramid of Face Verification as People Age

    Directory of Open Access Journals (Sweden)

    Ji-Xiang Du

    2014-01-01

    Full Text Available Face verification in the presence of age progression is an important problem that has not been widely addressed. In this paper, we propose to use the active appearance model (AAM and gradient orientation pyramid (GOP feature representation for this problem. First, we use the AAM on the dataset and generate the AAM images; we then get the representation of gradient orientation on a hierarchical model, which is the appearance of GOP. When combined with a support vector machine (SVM, experimental results show that our approach has excellent performance on two public domain face aging datasets: FGNET and MORPH. Second, we compare the performance of the proposed methods with a number of related face verification methods; the results show that the new approach is more robust and performs better.

  17. Identification and Assessment of Material Models for Age-Related Degradation of Structures and Passive Components in Nuclear Power Plants

    International Nuclear Information System (INIS)

    When performing seismic safety assessments of nuclear power plants (NPPs), the potential effects of age-related degradation on structures, systems, and components (SSCs) should be considered. To address the issue of aging degradation, the Korea Atomic Energy Research Institute (KAERI) has embarked on a five-year research project to develop a realistic seismic risk evaluation system which will include the consideration of aging of structures and components in NPPs. Three specific areas that are included in the KAERI research project, related to seismic probabilistic risk assessment (PRA), are probabilistic seismic hazard analysis, seismic fragility analysis including the effects of aging, and a plant seismic risk analysis. To support the development of seismic capability evaluation technology for degraded structures and components, KAERI entered into a collaboration agreement with Brookhaven National Laboratory (BNL) in 2007. The collaborative research effort is intended to continue over a five year period with the goal of developing seismic fragility analysis methods that consider the potential effects of age-related degradation of SSCs, and using these results as input to seismic PRAs. In the Year 1 scope of work BNL collected and reviewed degradation occurrences in US NPPs and identified important aging characteristics needed for the seismic capability evaluations that will be performed in the subsequent evaluations in the years that follow. This information is presented in the Annual Report for the Year 1 Task, identified as BNL Report-81741-2008 and also designated as KAERI/RR-2931/2008. The report presents results of the statistical and trending analysis of this data and compares the results to prior aging studies. In addition, the report provides a description of U.S. current regulatory requirements, regulatory guidance documents, generic communications, industry standards and guidance, and past research related to aging degradation of SSCs. This report

  18. Identification and Assessment of Material Models for Age-Related Degradation of Structures and Passive Components in Nuclear Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Nie,J.; Braverman, J.; Hofmayer, C.; Kim, M. K.; Choi, I-K.

    2009-04-27

    When performing seismic safety assessments of nuclear power plants (NPPs), the potential effects of age-related degradation on structures, systems, and components (SSCs) should be considered. To address the issue of aging degradation, the Korea Atomic Energy Research Institute (KAERI) has embarked on a five-year research project to develop a realistic seismic risk evaluation system which will include the consideration of aging of structures and components in NPPs. Three specific areas that are included in the KAERI research project, related to seismic probabilistic risk assessment (PRA), are probabilistic seismic hazard analysis, seismic fragility analysis including the effects of aging, and a plant seismic risk analysis. To support the development of seismic capability evaluation technology for degraded structures and components, KAERI entered into a collaboration agreement with Brookhaven National Laboratory (BNL) in 2007. The collaborative research effort is intended to continue over a five year period with the goal of developing seismic fragility analysis methods that consider the potential effects of age-related degradation of SSCs, and using these results as input to seismic PRAs. In the Year 1 scope of work BNL collected and reviewed degradation occurrences in US NPPs and identified important aging characteristics needed for the seismic capability evaluations that will be performed in the subsequent evaluations in the years that follow. This information is presented in the Annual Report for the Year 1 Task, identified as BNL Report-81741-2008 and also designated as KAERI/RR-2931/2008. The report presents results of the statistical and trending analysis of this data and compares the results to prior aging studies. In addition, the report provides a description of U.S. current regulatory requirements, regulatory guidance documents, generic communications, industry standards and guidance, and past research related to aging degradation of SSCs. This report

  19. Nonlinear dynamics in an OLG growth model with young and old age labour supply: the role of public health expenditure

    OpenAIRE

    Gori, Luca; Sodini, Mauro

    2011-01-01

    This paper analyses the dynamics of a two-dimensional overlapping generations model with young and old age labour supply. It is shown that the public provision of health investments, which, in turn, affects the demand for material consumption, may represent a source of local indeterminacy, nonlinear dynamics and multiplicity of equilibria. Furthermore, global indeterminacy may also occur because of the co-existence of two attractors with tangled basins of attraction.

  20. Spatially explicit modeling of 1992-2100 land cover and forest stand age for the conterminous United States.

    Science.gov (United States)

    Sohl, Terry L; Sayler, Kristi L; Bouchard, Michelle A; Reker, Ryan R; Friesz, Aaron M; Bennett, Stacie L; Sleeter, Benjamin M; Sleeter, Rachel R; Wilson, Tamara; Soulard, Chris; Knuppe, Michelle; Van Hofwegen, Travis

    2014-07-01

    Information on future land-use and land-cover (LULC) change is needed to analyze the impact of LULC change on ecological processes. The U.S. Geological Survey has produced spatially explicit, thematically detailed LULC projections for the conterminous United States. Four qualitative and quantitative scenarios of LULC change were developed, with characteristics consistent with the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emission Scenarios (SRES). The four quantified scenarios (A1B, A2, B1, and B2) served as input to the forecasting scenarios of land-use change (FORE-SCE) model. Four spatially explicit data sets consistent with scenario storylines were produced for the conterminous United States, with annual LULC maps from 1992 through 2100. The future projections are characterized by a loss of natural land covers in most scenarios, with corresponding expansion of anthropogenic land uses. Along with the loss of natural land covers, remaining natural land covers experience increased fragmentation under most scenarios, with only the B2 scenario remaining relatively stable in both the proportion of remaining natural land covers and basic fragmentation measures. Forest stand age was also modeled. By 2100, scenarios and ecoregions with heavy forest cutting had relatively lower mean stand ages compared to those with less forest cutting. Stand ages differed substantially between unprotected and protected forest lands, as well as between different forest classes. The modeled data were compared to the National Land Cover Database (NLCD) and other data sources to assess model characteristics. The consistent, spatially explicit, and thematically detailed LULC projections and the associated forest stand-age data layers have been used to analyze LULC impacts on carbon and greenhouse gas fluxes, biodiversity, climate and weather variability, hydrologic change, and other ecological processes. PMID:25154094

  1. Response of a zonal climate-ice sheet model to the orbital perturbations during the Quaternary ice ages

    OpenAIRE

    Pollard, David; Ingersoll, Andrew P.; Lockwood, John G.

    2011-01-01

    The astronomical theory of the ice ages is investigated using a simple climate model which includes the ice sheets explicitly. A one-level, zonally averaged, seasonal energy-balance equation is solved numerically for sea-level temperature T as a function of latitude and month (similar to North, 1975). Seasonally varying snow cover (which affects planetary albedo) is included diagnostically by parameterizing monthly snowfall and snowmelt in simple ways. The net annual accumulation and ablation...

  2. Feeding the periphery : modeling early Bronze Age economies and the cultural landscape of the Faynan District, Southern Jordan

    OpenAIRE

    Muniz, Adolfo A.

    2007-01-01

    The current study investigates the evolution of southern Levantine societies during the early Bronze Age (ca 3600- 2000 BCE). This study contributes to the reinvestigation of the food systems concept, a concept that addresses the interconnectivity of subsistence strategies and the larger natural and social environment. Investigating complex social processes within a food systems approach is not a new concept, but few systematic frameworks have modeled the scope and structure of varying levels...

  3. An Age-Structured Approach to Modelling Behavioural Variation Maintained by Life-History Trade-Offs

    OpenAIRE

    Matthew H T Chan; Kim, Peter S.

    2014-01-01

    There have been numerous empirical studies on the fitness consequences of behavioural syndromes in various animal taxa; however, the ecological and evolutionary implications on a population level are still poorly understood. To better understand these implications, we develop a non-linear age-structured mathematical model to qualitatively examine the evolutionary consequences of a heritable boldness personality trait within an animal population. We assume that this heritable boldness trait is...

  4. Spatially explicit modeling of 1992-2100 land cover and forest stand age for the conterminous United States

    Science.gov (United States)

    Sohl, Terry L.; Sayler, Kristi L.; Bouchard, Michelle; Reker, Ryan R.; Friesz, Aaron M.; Bennett, Stacie L.; Sleeter, Benjamin M.; Sleeter, Rachel R.; Wilson, Tamara; Knuppe, Michelle; Van Hofwegen, Travis

    2014-01-01

    Information on future land-use and land-cover (LULC) change is needed to analyze the impact of LULC change on ecological processes. The U.S. Geological Survey has produced spatially explicit, thematically detailed LULC projections for the conterminous United States. Four qualitative and quantitative scenarios of LULC change were developed, with characteristics consistent with the Intergovernmental Panel on Climate Change (IPCC) Special Report on 5 Emission Scenarios (SRES). The four quantified scenarios (A1B, A2, B1, and B2) served as input to the Forecasting Scenarios of Land-use Change (FORE-SCE) model. Four spatially explicit datasets consistent with scenario storylines were produced for the conterminous United States, with annual LULC maps from 1992 through 2100. The future projections are characterized by a loss of natural land covers in most scenarios, with corresponding expansion of 10 anthropogenic land uses. Along with the loss of natural land covers, remaining natural land covers experience increased fragmentation under most scenarios, with only the B2 scenario remaining relatively stable in both proportion of remaining natural land covers and basic fragmentation measures. Forest stand age was also modeled. By 2100, scenarios and ecoregions with heavy forest cutting have relatively lower mean stand ages compared to those with less 15 forest cutting. Stand ages differ substantially between unprotected and protected forest lands, as well as between different forest classes. The modeled data were compared to the National Land Cover Database (NLCD) and other data sources to assess model characteristics. The consistent, spatially explicit, and thematically detailed LULC projections and the associated forest stand age data layers have been used to analyze LULC impacts on carbon and greenhouse gas fluxes, 20 biodiversity, climate and weather variability, hydrologic change, and other ecological processes.

  5. A Bayesian modeling approach for estimation of a shape-free groundwater age distribution using multiple tracers

    International Nuclear Information System (INIS)

    Highlights: • A Bayesian method is used to infer the freeform (histogram) age distributions. • The value at each bin was estimated using MCMC approach. • The method was applied to a synthetic tracer dataset and two real datasets. • The cumulative age distribution is captured better than the non-cumulative. • Less uncertainty is obtained when smaller number of bins is used. - Abstract: Due to the mixing of groundwaters with different ages in aquifers, groundwater age is more appropriately represented by a distribution rather than a scalar number. To infer a groundwater age distribution from environmental tracers, a mathematical form is often assumed for the shape of the distribution and the parameters of the mathematical distribution are estimated using deterministic or stochastic inverse methods. The prescription of the mathematical form limits the exploration of the age distribution to the shapes that can be described by the selected distribution. In this paper, the use of freeform histograms as groundwater age distributions is evaluated. A Bayesian Markov Chain Monte Carlo approach is used to estimate the fraction of groundwater in each histogram bin. The method was able to capture the shape of a hypothetical gamma distribution from the concentrations of four age tracers. The number of bins that can be considered in this approach is limited based on the number of tracers available. The histogram method was also tested on tracer data sets from Holten (The Netherlands; 3H, 3He, 85Kr, 39Ar) and the La Selva Biological Station (Costa-Rica; SF6, CFCs, 3H, 4He and 14C), and compared to a number of mathematical forms. According to standard Bayesian measures of model goodness, the best mathematical distribution performs better than the histogram distributions in terms of the ability to capture the observed tracer data relative to their complexity. Among the histogram distributions, the four bin histogram performs better in most of the cases. The Monte Carlo

  6. Anti-Aging Effect of Adipose-Derived Stem Cells in a Mouse Model of Skin Aging Induced by D-Galactose

    OpenAIRE

    Zhang, Shengchang; Dong, Ziqing; Peng, Zhangsong; Lu, Feng

    2014-01-01

    Introduction Glycation products accumulate during aging of slowly renewing tissue, including skin, and are suggested as an important mechanism underlying the skin aging process. Adipose-derived cells are widely used in the clinic to treat ischemic diseases and enhance wound healing. Interestingly, adipose-derived stem cells (ASCs) are also effective in anti-aging therapy, although the mechanism underlying their effects remains unknown. The purpose of the present study was to examine the anti-...

  7. Surveillance test and monitoring strategy for the availability improvement of standby equipment using age-dependent model

    International Nuclear Information System (INIS)

    In many cases, the safety of a nuclear power plant greatly depends on the successful operation of specific standby equipment at the time of demand arrival. For the effective management of safety-critical standby equipment, unavailability measures are introduced and widely applied. In this study, we propose an age-dependent unavailability model for standby equipment that considers aging-relevant information, such as the number of actual operations, the elapsed time from installation, and maintenance activities, in an integrated manner. Based on the proposed model, we present two availability enhancement strategies: the Online Monitoring based Inspection Method (OMIM) and the Shortening Surveillance Test Interval Method (SSTIM). In the OMIM, ‘elapsed-time sensitive' elements are monitored, without actual operation, at the differentiated monitoring interval with the help of sensing devices. For the remaining parts of the elements, actual testing is performed with an adaptive interval for each standby turn by the SSTIM. The effectiveness of the proposed enhancement schemes is demonstrated through a case study for the motor-operated valve (MOV). It is our belief that the proposed schemes can be widely applied in areas such as equipment testing, maintenance strategies, dynamic probabilistic safety assessment (PSA), and risk-informed regulations. - Highlights: • An age-dependent unavailability model for standby equipment was investigated. • An Online Monitoring-based Inspection Method was suggested. • Changing the test interval for each standby turn was suggested. • The effectiveness of the suggested methods was analyzed quantitatively

  8. Constructing Regional Groundwater Models from Geophysical Data of Varying Type, Age, and Quality

    DEFF Research Database (Denmark)

    Vest Christiansen, Anders; Auken, Esben; Marker, Pernille Aabye; Vilhelmsen, Troels Norvin; Foged, Nikolaj; Wernberg, Thomas; Bauer-Gottwein, Peter

    methodology by show-casing a study from Denmark were a regional groundwater model is constructed by including lithological information from 3100 boreholes over an 710 sqkm area. The geophysical models spans more than 30 years of data collection and includes approx. 225,000 DC models, and 35,000 EM models......Regional hydrological models are important tools in water resources management, but prediction uncertainties are often high due to non-uniqueness of the hydrostratigraphical model. This model is often based on borehole lithology only. However, a much better resolution can be obtained from large...... geophysical datasets covering the entire domain. Using boreholes to link between hydrostratigraphical classes and resistivity is efficient and emphasizes the need for an all-inclusive data interpretation procedure that can be integrated in groundwater model calibration. We present an automatic method for...

  9. The Impact of Population Ageing on the Labour Market: Evidence from Overlapping Generations Computable General Equilibrium (OLG-CGE) Model of Scotland

    OpenAIRE

    Lisenkova, Katerina; Mérette, Marcel; Wright, Robert

    2012-01-01

    This paper presents a dynamic Overlapping Generations Computable General Equilibrium (OLG-CGE) model of Scotland. The model is used to examine the impact of population ageing on the labour market. More specifically, it is used to evaluate the effects of labour force decline and labour force ageing on key macro-economic variables. The second effect is assumed to operate through age-specific productivity and labour force participation. In the analysis, particular attention is paid to how popula...

  10. Age-dependent decline in learning and memory performances of WAG/Rij rat model of absence epilepsy

    OpenAIRE

    Karson Ayşe; Utkan Tijen; Balcı Fuat; Arıcıoğlu Feyza; Ateş Nurbay

    2012-01-01

    RESEARCH Open Access Age-dependent decline in learning and memory performances of WAG/Rij rat model of absence epilepsy Ayşe Karson1*, Tijen Utkan2, Fuat Balcı3, Feyza Arıcıoğlu4 and Nurbay Ateş1 Abstract Recent clinical studies revealed emotional and cognitive impairments associated with absence epilepsy. Preclinical research with genetic models of absence epilepsy however have primarily focused on dysfunctional emotional processes and paid relatively less attention t...

  11. Precipitation Hardening and Statistical Modeling of the Aging Parameters and Alloy Compositions in Al-Cu-Mg-Ag Alloys

    Science.gov (United States)

    Al-Obaisi, A. M.; El-Danaf, E. A.; Ragab, A. E.; Soliman, M. S.

    2016-06-01

    The addition of Ag to Al-Cu-Mg systems has been proposed to replace the existing high-strength 2xxx and 7xxx Al alloys. The aged Al-Cu-Mg-Ag alloys exhibited promising properties, due to special type of precipitates named Ω, which cooperate with other precipitates to enhance the mechanical properties significantly. In the present investigation, the effect of changing percentages of alloying elements, aging time, and aging temperature on the hardness values was studied based on a factorial design. According to this design of experiments (DOE)—23 factorial design, eight alloys were cast and hot rolled, where (Cu, Mg, and Ag) were added to aluminum with two different levels for each alloying element. These alloys were aged at different temperatures (160, 190, and 220 °C) over a wide range of time intervals from 10 min. to 64 h. The resulting hardness data were used as an input for Minitab software to model and relate the process variables with hardness through a regression analysis. Modifying the alloying elements' weight percentages to the high level enhanced the hardness of the alloy with about 40% as compared to the alloy containing the low level of all alloying elements. Through analysis of variance (ANOVA), it was figured out that altering the fraction of Cu had the greatest effect on the hardness values with a contribution of about 49%. Also, second-level interaction terms had about 21% of impact on the hardness values. Aging time, quadratic terms, and third-level interaction terms had almost the same level of influence on hardness values (about 10% contribution). Furthermore, the results have shown that small addition of Mg and Ag was enough to improve the mechanical properties of the alloy significantly. The statistical model formulated interpreted about 80% of the variation in hardness values.

  12. U-Pb age and Hf-O isotopes of detrital zircons from Hainan Island: Implications for Mesozoic subduction models

    Science.gov (United States)

    Jiang, Xiao-Yan; Li, Xian-Hua; Collins, W. J.; Huang, Hui-Qing

    2015-12-01

    A compilation of magmatic ages from the Mesozoic South China Block suggests a number of "magmatic quiescence" periods at ca. 205-195 Ma, ca. 150-140 Ma and ca. 125-115 Ma, casting doubt on tectonic models that suggest ongoing Andean-type subduction along the South China continental margin. However, SIMS U-Pb analyses on two detrital zircon samples from the Cretaceous Lumuwan Formation on Hainan Island, southeast China, reveal three major age peaks at ca. 120 Ma, ca. 155 Ma and ca. 235 Ma. Zircons of these ages are mostly euhedral and show typical magmatic oscillatory zoning, suggesting short-distance transport from nearby magmatic sources. The extremely rare occurrence of ca. 120 Ma magmatic records onshore suggests that detrital zircons of this age population may be derived from a source proximal to Hainan Island but presently missing. Therefore, our data provide new evidence for ongoing magmatic activity in late Mesozoic South China. In situ Hf and O isotope analyses of the Mesozoic detrital zircons reveal large variations in both εHf(t) (- 21.2 to 10.5) and δ18O (4.4‰ to 13.6‰) values. A general negative correlation between them suggests the reworking of old supracrustal materials (average crustal residence age of ca. 2.0 Ga) by juvenile mantle-derived magmas. The progression of increasing εHf(t) and decreasing δ18O values of zircons from the Triassic to the Cretaceous suggests progressive crustal growth during the Mesozoic. The results are consistent with hybridization at an active continental margin. We briefly review tectonic models for the Indosinian orogeny and suggest that the petrologic evidence indicates that Mesozoic magmatism was part of the circum-Pacific accretionary orogens that formed along the continental margin of East Asia no later than ca. 250 Ma and continued at least to the late Cretaceous.

  13. Reaction norms models in the adjusted weight at 550 days of age for Polled Nellore cattle in Northeast Brazil

    Directory of Open Access Journals (Sweden)

    Diego Pagung Ambrosini

    2014-07-01

    Full Text Available The objective of this study was to evaluate the genotype-environment interaction (GEI in the body weight adjusted to 550 days of age (W550 of Polled Nellore cattle raised in Northeastern Brazil using reaction norms (RN models. Hierarchical RN models included fixed effects for age of cow (linear and quadratic and random effects for contemporary groups (CG and additive genetic RN level and slope. Four RN hierarchical models (RNHM were used. The RNHM2S uses the solutions of contemporary groups estimated by the standard animal model (AM and considers them as environmental level for predicting the reaction norms and the RNHM1S, which jointly estimate these two sets of unknowns. Two versions were considered for both models, one with a homogeneous (Hm and another with a heterogeneous (He residual variance. The one-step homogeneous residual variance model (RNHM1SHm offered better adjustment to the data when compared with other models. For the RNHM1SHm model, estimates of additive genetic variance and heritability increased with environment improvement (260.75±75.80 kg2 to 4298.39±356.56 kg2 and 0.22±0.05 to 0.82±0.01, for low- and high-performance environments, respectively. High correlation (0.97±0.01 between the intercept and the slope of RN shows that animals with higher genetic values respond better to environment improvement. In the evaluation of breeding sires with higher genetic values in the various environments using Spearman's correlation, values between 0 and 0.98 were observed, pointing to high reclassification, especially among genetic values obtained by the animal model in comparison with those obtained via RNHM1SHm. The existence of GEI is confirmed, and so is the need for specific evaluations for low, medium and high level production environments.

  14. Age-structured dynamic, stochastic and mechanistic simulation model of Salmonella Dublin infection within dairy herds

    DEFF Research Database (Denmark)

    Nielsen, Liza Rosenbaum; Kudahl, Anne Margrethe Braad; Østergaard, Søren

    2012-01-01

    six age-groups; 2) S. Dublin incidence and number of animals in each infection state; and 3) S. Dublin related morbidity and mortality in the acutely infected animals. The effects of introducing one infectious heifer on the risk of spread of S. Dublin within the herd and on the duration of infection...... individual animals in each of the six age groups in the herd. The hygiene level was highly influential on the probability that the infection spread within the herd, duration of infection and epidemic size. The herd susceptibility level was also influential, but not likely to provide sufficient prevention and...... probability of extinction. In general, disease and mortality patterns followed epidemic waves in the herds. However, an interesting pattern was seen for acute infections and abortions in adult cattle after the first 2 years of infection in herds with poor hygiene and high susceptibility. Repeated infections...

  15. Proportionality in Age Discrimination Cases - a Model Suitable for Socially Embedded Rights

    OpenAIRE

    Schiek, Dagmar

    2015-01-01

    This chapter discusses the use of proportionality in age discrimination cases before the Court of Justice of the European Union. It argues that the Court does not use this concept systematically - indeed it exposes some contradiction that make the case law seem arbitrary - and proposes a more fruitful use of the principle, which is in line with a modern conception of human rights. The chapter argues that the principle of proportionality stems from the time when human rights served the recentl...

  16. Quantification the Effect of Ageing on Characteristics of the Photoplethysmogram Using an Optimized Windkessel Model

    OpenAIRE

    Doostdar, H; Khalilzadeh, MA

    2014-01-01

    Background: With increasing age, some changes appeared in specifications of vessels which including dimensions and elasticity in theirs. The changes in parameters such as resistance, inertance and compliance vessels appear and eventually changes in the environmental pulse releases are in circulation. These changes clearly appear in specification of photoplethysmogram particularly in the size and position signals second peak is observed. Aim and scope: The aim of study was to Circulatory syste...

  17. Face Prediction Model for an Automatic Age-invariant Face Recognition System

    OpenAIRE

    Yadav, Poonam

    2015-01-01

    Automated face recognition and identification softwares are becoming part of our daily life; it finds its abode not only with Facebook's auto photo tagging, Apple's iPhoto, Google's Picasa, Microsoft's Kinect, but also in Homeland Security Department's dedicated biometric face detection systems. Most of these automatic face identification systems fail where the effects of aging come into the picture. Little work exists in the literature on the subject of face prediction that accounts for agin...

  18. Characterizing Cognitive Aging of Working Memory and Executive Function in Animal Models

    OpenAIRE

    Jennifer Lynn Bizon; Alexander, Gene E.

    2012-01-01

    Executive functions supported by prefrontal cortical (PFC) systems provide essential control and planning mechanisms to guide goal-directed behavior. As such, age-related alterations in executive functions can mediate profound and widespread deficits on a diverse array of neurocognitive processes. Many of the critical neuroanatomical and functional characteristics of prefrontal cortex are preserved in rodents, allowing for meaningful cross species comparisons relevant to the study of cognitiv...

  19. Age Discrimination in the Allocation of Research Funds: The Dutch Model

    OpenAIRE

    Wolfgang Stroebe

    2009-01-01

    The major funding source for fundamental scientific research in the Netherlands (NWO), reserves more than half of their research budget for grants for young researchers. Researchers, who received their doctorate more than 15 years ago, cannot apply. Apparently NWO believes in a negative correlation between age and scientific creativity or productivity. This article reviews research on this relationship and concludes that there is no evidence to support the myth that science is a young person?...

  20. Concrete early age basic creep: Experiments and test of rheological modelling approaches

    OpenAIRE

    Briffaut, Matthieu; BENBOUDJEMA, Farid; Torrenti, Jean Michel; Nahas, Georges

    2012-01-01

    At early-age, hydration of cement leads to a reduction of volume (caused by the Le Chatelier contraction) which induces autogeneous shrinkage. Besides, hydration is an exothermic reaction and an increase of temperature occurs (followed by a decrease). As autogeneous shrinkage arises only in cement paste and as coefficient of thermal expansion may be different between cement paste and aggregates, strains incompatibilities lead to an internal self-equilibrated state of stress. Depending especia...