Science.gov

Sample records for abundance age structure

  1. Spatio-Temporal Variation in Age Structure and Abundance of the Endangered Snail Kite: Pooling across Regions Masks a Declining and Aging Population

    PubMed Central

    Kendall, William L.; Fletcher, Robert J.; Kitchens, Wiley M.

    2016-01-01

    While variation in age structure over time and space has long been considered important for population dynamics and conservation, reliable estimates of such spatio-temporal variation in age structure have been elusive for wild vertebrate populations. This limitation has arisen because of problems of imperfect detection, the potential for temporary emigration impacting assessments of age structure, and limited information on age. However, identifying patterns in age structure is important for making reliable predictions of both short- and long-term dynamics of populations of conservation concern. Using a multistate superpopulation estimator, we estimated region-specific abundance and age structure (the proportion of individuals within each age class) of a highly endangered population of snail kites for two separate regions in Florida over 17 years (1997–2013). We find that in the southern region of the snail kite—a region known to be critical for the long-term persistence of the species—the population has declined significantly since 1997, and during this time, it has increasingly become dominated by older snail kites (> 12 years old). In contrast, in the northern region—a region historically thought to serve primarily as drought refugia—the population has increased significantly since 2007 and age structure is more evenly distributed among age classes. Given that snail kites show senescence at approximately 13 years of age, where individuals suffer higher mortality rates and lower breeding rates, these results reveal an alarming trend for the southern region. Our work illustrates the importance of accounting for spatial structure when assessing changes in abundance and age distribution and the need for monitoring of age structure in imperiled species. PMID:27681854

  2. Divergent patterns of abundance and age-class structure of headwater stream tadpoles in burned and unburned watersheds

    USGS Publications Warehouse

    Hossack, B.R.; Corn, P.S.; Fagre, D.B.

    2006-01-01

    Wildfire is a potential threat to many species with narrow environmental tolerances like the Rocky Mountain tailed frog (Ascaphus montanus Mittleman and Myers, 1949), which inhabits a region where the frequency and intensity of wildfires are expected to increase. We compared pre- and post-fire counts of tadpoles in eight streams in northwestern Montana to determine the effects of wildfire on A. montanus. All streams were initially sampled in 2001, 2 years before four of them burned in a large wildfire, and were resampled during the 2 years following the fire. Counts of tadpoles were similar in the two groups of streams before the fire. After the fire, tadpoles were almost twice as abundant in unburned streams than in burned streams. The fire seemed to have the greatest negative effect on abundance of age-1 tadpoles, which was reflected in the greater variation in same-stream age-class structure compared with those in unburned streams. Despite the apparent effect on tadpoles, we do not expect the wildfire to be an extirpation threat to populations in the streams that we sampled. Studies spanning a chronosequence of fires, as well as in other areas, are needed to assess the effects of fires on streams with A. montanus and to determine the severity and persistence of these effects.

  3. Age-abundance relationships for neutral communities.

    PubMed

    Danino, Matan; Shnerb, Nadav M

    2015-10-01

    Neutral models for the dynamics of a system of competing species are often used to describe a wide variety of empirical communities. These models are used in many situations, ranging from population genetics and ecological biodiversity to macroevolution and cancer tumors. One of the main issues discussed within this framework is the relationships between the abundance of a species and its age. Here we provide a comprehensive analysis of the age-abundance relationships for fixed-size and growing communities. Explicit formulas for the average and the most likely age of a species with abundance n are given, together with the full probability distribution function. We further discuss the universality of these results and their applicability to the tropical forest community. PMID:26565271

  4. Age-abundance relationships for neutral communities

    NASA Astrophysics Data System (ADS)

    Danino, Matan; Shnerb, Nadav M.

    2015-10-01

    Neutral models for the dynamics of a system of competing species are often used to describe a wide variety of empirical communities. These models are used in many situations, ranging from population genetics and ecological biodiversity to macroevolution and cancer tumors. One of the main issues discussed within this framework is the relationships between the abundance of a species and its age. Here we provide a comprehensive analysis of the age-abundance relationships for fixed-size and growing communities. Explicit formulas for the average and the most likely age of a species with abundance n are given, together with the full probability distribution function. We further discuss the universality of these results and their applicability to the tropical forest community.

  5. Rb, Sr and strontium isotopic composition, K/Ar age and large ion lithophile trace element abundances in rocks and glasses from the Wanapitei Lake impact structure

    NASA Technical Reports Server (NTRS)

    Winzer, S. R.; Lum, R. K. L.; Schuhmann, S.

    1976-01-01

    Shock metamorphosed rocks and shock-produced melt glasses from the Wanapitei Lake impact structure have been examined petrographically and by electron microprobe. Eleven clasts exhibiting varying degrees of shock metamorphism and eight impact-produced glasses have been analyzed for Rb, Sr and Sr isotopic composition. Five clasts and one glass have also been analyzed for large ion lithophile (LIL) trace element abundances including Li, Rb, Sr, and Ba and the REE's. The impact event forming the Wanapitei Lake structure occurred 37 m.y. ago based on K/Ar dating of glass and glassy whole-rock samples. Rb/Sr isotopic dating failed to provide a meaningful whole-rock or internal isochron. The isotopic composition of the glasses can be explained by impact-produced mixing and melting of metasediments.

  6. Correlation between lithium abundances and ages of solar twin stars

    NASA Astrophysics Data System (ADS)

    Carlos, Marília; Nissen, Poul E.; Meléndez, Jorge

    2016-03-01

    Aims: We want to determine the lithium abundances of solar twin stars as a function of stellar age to provide constraints for stellar evolutions models and to investigate whether there is a connection between low Li abundance and the occurrence of planets. Methods: For a sample of 21 solar twins observed with the HARPS spectrograph at high spectral resolution (R ≃ 115.000) and very high signal-to-noise ratio (600 ≤ S/N ≤ 2400), precise lithium abundances were obtained by spectral synthesis of the Li i 6707.8 Å line and compared to stellar ages, masses, and metallicities determined from a spectroscopic analysis of the same set of HARPS spectra. Results: We show that for the large majority of the solar twins there is a strong correlation between lithium abundance and stellar age. As the age increases from 1 to 9 Gyr, the Li abundance decreases by a factor of ~50. The relation agrees fairly well with predictions from non-standard stellar evolution models of Li destruction at the bottom of the upper convection zone. Two stars deviate from the relation by having Li abundances enhanced by a factor of ~10, which may be due to planet engulfment. On the other hand, we find no indication of a link between planet hosting stars and enhanced lithium depletion. Based on data products from observations made with ESO Telescopes at the La Silla Paranal Observatory, (observing programs 072.C-0488, 183.C-0972, 188.C-0265, and 0.88.C-0323).

  7. How selection structures species abundance distributions

    PubMed Central

    Magurran, Anne E.; Henderson, Peter A.

    2012-01-01

    How do species divide resources to produce the characteristic species abundance distributions seen in nature? One way to resolve this problem is to examine how the biomass (or capacity) of the spatial guilds that combine to produce an abundance distribution is allocated among species. Here we argue that selection on body size varies across guilds occupying spatially distinct habitats. Using an exceptionally well-characterized estuarine fish community, we show that biomass is concentrated in large bodied species in guilds where habitat structure provides protection from predators, but not in those guilds associated with open habitats and where safety in numbers is a mechanism for reducing predation risk. We further demonstrate that while there is temporal turnover in the abundances and identities of species that comprise these guilds, guild rank order is conserved across our 30-year time series. These results demonstrate that ecological communities are not randomly assembled but can be decomposed into guilds where capacity is predictably allocated among species. PMID:22787020

  8. Red giant masses and ages derived from carbon and nitrogen abundances

    NASA Astrophysics Data System (ADS)

    Martig, Marie; Fouesneau, Morgan; Rix, Hans-Walter; Ness, Melissa; Mészáros, Szabolcs; García-Hernández, D. A.; Pinsonneault, Marc; Serenelli, Aldo; Silva Aguirre, Victor; Zamora, Olga

    2016-03-01

    We show that the masses of red giant stars can be well predicted from their photospheric carbon and nitrogen abundances, in conjunction with their spectroscopic stellar labels log g, Teff, and [Fe/H]. This is qualitatively expected from mass-dependent post-main-sequence evolution. We here establish an empirical relation between these quantities by drawing on 1475 red giants with asteroseismic mass estimates from Kepler that also have spectroscopic labels from Apache Point Observatory Galactic Evolution Experiment (APOGEE) DR12. We assess the accuracy of our model, and find that it predicts stellar masses with fractional rms errors of about 14 per cent (typically 0.2 M⊙). From these masses, we derive ages with rms errors of 40 per cent. This empirical model allows us for the first time to make age determinations (in the range 1-13 Gyr) for vast numbers of giant stars across the Galaxy. We apply our model to ˜52 000 stars in APOGEE DR12, for which no direct mass and age information was previously available. We find that these estimates highlight the vertical age structure of the Milky Way disc, and that the relation of age with [α/M] and metallicity is broadly consistent with established expectations based on detailed studies of the solar neighbourhood.

  9. Phylogenetic structure and host abundance drive disease pressure in communities.

    PubMed

    Parker, Ingrid M; Saunders, Megan; Bontrager, Megan; Weitz, Andrew P; Hendricks, Rebecca; Magarey, Roger; Suiter, Karl; Gilbert, Gregory S

    2015-04-23

    Pathogens play an important part in shaping the structure and dynamics of natural communities, because species are not affected by them equally. A shared goal of ecology and epidemiology is to predict when a species is most vulnerable to disease. A leading hypothesis asserts that the impact of disease should increase with host abundance, producing a 'rare-species advantage'. However, the impact of a pathogen may be decoupled from host abundance, because most pathogens infect more than one species, leading to pathogen spillover onto closely related species. Here we show that the phylogenetic and ecological structure of the surrounding community can be important predictors of disease pressure. We found that the amount of tissue lost to disease increased with the relative abundance of a species across a grassland plant community, and that this rare-species advantage had an additional phylogenetic component: disease pressure was stronger on species with many close relatives. We used a global model of pathogen sharing as a function of relatedness between hosts, which provided a robust predictor of relative disease pressure at the local scale. In our grassland, the total amount of disease was most accurately explained not by the abundance of the focal host alone, but by the abundance of all species in the community weighted by their phylogenetic distance to the host. Furthermore, the model strongly predicted observed disease pressure for 44 novel host species we introduced experimentally to our study site, providing evidence for a mechanism to explain why phylogenetically rare species are more likely to become invasive when introduced. Our results demonstrate how the phylogenetic and ecological structure of communities can have a key role in disease dynamics, with implications for the maintenance of biodiversity, biotic resistance against introduced weeds, and the success of managed plants in agriculture and forestry.

  10. Climate change effects on soil microarthropod abundance and community structure

    SciTech Connect

    Kardol, Paul; Reynolds, W. Nicholas; Norby, Richard J; Classen, Aimee T

    2011-01-01

    Long-term ecosystem responses to climate change strongly depend on how the soil subsystem and its inhabitants respond to these perturbations. Using open-top chambers, we studied the response of soil microarthropods to single and combined effects of ambient and elevated atmospheric [CO{sub 2}], ambient and elevated temperatures and changes in precipitation in constructed old-fields in Tennessee, USA. Microarthropods were assessed five years after treatments were initiated and samples were collected in both November and June. Across treatments, mites and collembola were the most dominant microarthropod groups collected. We did not detect any treatment effects on microarthropod abundance. In November, but not in June, microarthropod richness, however, was affected by the climate change treatments. In November, total microarthropod richness was lower in dry than in wet treatments, and in ambient temperature treatments, richness was higher under elevated [CO{sub 2}] than under ambient [CO{sub 2}]. Differential responses of individual taxa to the climate change treatments resulted in shifts in community composition. In general, the precipitation and warming treatments explained most of the variation in community composition. Across treatments, we found that collembola abundance and richness were positively related to soil moisture content, and that negative relationships between collembola abundance and richness and soil temperature could be explained by temperature-related shifts in soil moisture content. Our data demonstrate how simultaneously acting climate change factors can affect the structure of soil microarthropod communities in old-field ecosystems. Overall, changes in soil moisture content, either as direct effect of changes in precipitation or as indirect effect of warming or elevated [CO{sub 2}], had a larger impact on microarthropod communities than did the direct effects of the warming and elevated [CO{sub 2}] treatments. Moisture-induced shifts in soil

  11. Structural aging program status report

    SciTech Connect

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

    1995-04-01

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

  12. Community structure influences species' abundance along environmental gradients.

    PubMed

    Eloranta, Antti P; Helland, Ingeborg P; Sandlund, Odd T; Hesthagen, Trygve; Ugedal, Ola; Finstad, Anders G

    2016-01-01

    Species' response to abiotic environmental variation can be influenced by local community structure and interspecific interactions, particularly in restricted habitats such as islands and lakes. In temperate lakes, future increase in water temperature and run-off of terrestrial (allochthonous) dissolved organic carbon (DOC) are predicted to alter community composition and the overall ecosystem productivity. However, little is known about how the present community structure and abiotic environmental variation interact to affect the abundance of native fish populations. We used a space-for-time approach to study how local community structure interact with lake morphometric and climatic characteristics (i.e. temperature and catchment productivity) to affect brown trout (Salmo trutta L.) yield in 283 Norwegian lakes located in different biogeographical regions. Brown trout yield (based on data from standardized survey gill net fishing; g 100 m(-2) gill net night(-1)) was generally lower in lakes where other fish species were present than in lakes with brown trout only. The yield showed an overall negative relationship with increasing temperature and a positive relationship with lake shoreline complexity. Brown trout yield was also negatively correlated with DOC load (measured using Normalized Difference Vegetation Index as a proxy) and lake size and depth (measured using terrain slope as a proxy), but only in lakes where other fish species were present. The observed negative response of brown trout yield to increasing DOC load and proportion of the pelagic open-water area is likely due to restricted (littoral) niche availability and competitive dominance of more pelagic fishes such as Arctic charr (Salvelinus alpinus (L.)). Our study highlights that, through competitive interactions, the local community structure can influence the response of a species' abundance to variation in abiotic conditions. Changes in biomass and niche use of top predators (such as the brown

  13. Motor abundance and control structure in the golf swing.

    PubMed

    Morrison, A; McGrath, D; Wallace, E S

    2016-04-01

    Variability and control structure are under-represented areas of golf swing research. This study investigated the use of the abundant degrees of freedom in the golf swing of high and intermediate skilled golfers using uncontrolled manifold (UCM) analysis. The variance parallel to (VUCM) and orthogonal to (VOrth) the UCM with respect to the orientation and location of the clubhead were calculated. The higher skilled golfers had proportionally higher values of VUCM than lower skilled players for all measured outcome variables. Motor synergy was found in the control of the orientation of the clubhead and the combined outcome variables but not for clubhead location. Clubhead location variance zeroed-in on impact as has been previously shown, whereas clubhead orientation variance increased near impact. Both skill levels increased their control over the clubhead location leading up to impact, with more control exerted over the clubhead orientation in the early downswing. The results suggest that to achieve higher skill levels in golf may not lie simply in optimal technique, but may lie more in developing control over the abundant degrees of freedom in the body.

  14. Structure and Abundance of Nitrous Oxide Complexes in Earth's Atmosphere.

    PubMed

    Salmon, Steven R; de Lange, Katrina M; Lane, Joseph R

    2016-04-01

    We have investigated the lowest energy structures and binding energies of a series of atmospherically relevant nitrous oxide (N2O) complexes using explicitly correlated coupled cluster theory. Specifically, we have considered complexes with nitrogen (N2-N2O), oxygen (O2-N2O), argon (Ar-N2O), and water (H2O-N2O). We have calculated rotational constants and harmonic vibrational frequencies for the complexes and the constituent monomers. Statistical mechanics was used to determine the thermodynamic parameters for complex formation as a function of temperature and pressure. These results, in combination with relevant atmospheric data, were used to estimate the abundance of N2O complexes in Earth's atmosphere as a function of altitude. We find that the abundance of N2O complexes in Earth's atmosphere is small but non-negligible, and we suggest that N2O complexes may contribute to absorption of terrestrial radiation and be relevant for understanding the atmospheric fate of N2O.

  15. Motor abundance and control structure in the golf swing.

    PubMed

    Morrison, A; McGrath, D; Wallace, E S

    2016-04-01

    Variability and control structure are under-represented areas of golf swing research. This study investigated the use of the abundant degrees of freedom in the golf swing of high and intermediate skilled golfers using uncontrolled manifold (UCM) analysis. The variance parallel to (VUCM) and orthogonal to (VOrth) the UCM with respect to the orientation and location of the clubhead were calculated. The higher skilled golfers had proportionally higher values of VUCM than lower skilled players for all measured outcome variables. Motor synergy was found in the control of the orientation of the clubhead and the combined outcome variables but not for clubhead location. Clubhead location variance zeroed-in on impact as has been previously shown, whereas clubhead orientation variance increased near impact. Both skill levels increased their control over the clubhead location leading up to impact, with more control exerted over the clubhead orientation in the early downswing. The results suggest that to achieve higher skill levels in golf may not lie simply in optimal technique, but may lie more in developing control over the abundant degrees of freedom in the body. PMID:26784706

  16. Quantitative Analysis of Age Specific Variation in the Abundance of Human Female Parotid Salivary Proteins

    PubMed Central

    Ambatipudi, Kiran S.; Lu, Bingwen; Hagen, Fred K; Melvin, James E.; Yates, John R.

    2010-01-01

    Summary Human saliva is a protein-rich, easily accessible source of potential local and systemic biomarkers to monitor changes that occur under pathological conditions; however little is known about the changes in abundance associated with normal aging. In this study, we performed a comprehensive proteomic profiling of pooled saliva collected from the parotid glands of healthy female subjects, divided into two age groups 1 and 2 (20–30 and 55–65 years old, respectively). Hydrophobic charge interaction chromatography was used to separate high from low abundant proteins prior to characterization of the parotid saliva using multidimensional protein identification technology (MudPIT). Collectively, 532 proteins were identified in the two age groups. Of these proteins, 266 were identified exclusively in one age group, while 266 proteins were common to both groups. The majority of the proteins identified in the two age groups belonged to the defense and immune response category. Of note, several defense related proteins (e.g. lysozyme, lactoferrin and histatin-1) were significantly more abundant in group 2 as determined by G-test. Selected representative mass spectrometric findings were validated by western blot analysis. Our study reports the first quantitative analysis of differentially regulated proteins in ductal saliva collected from young and older female subjects. This study supports the use of high-throughput proteomics as a robust discovery tool. Such results provide a foundation for future studies to identify specific salivary proteins which may be linked to age-related diseases specific to women. PMID:19764810

  17. THE IMPACT OF ENHANCED He AND CNONa ABUNDANCES ON GLOBULAR CLUSTER RELATIVE AGE-DATING METHODS

    SciTech Connect

    MarIn-Franch, Antonio; Aparicio, Antonio; Cassisi, Santi; Pietrinferni, Adriano E-mail: antapaj@iac.e E-mail: pietrinferni@oa-teramo.inaf.i

    2010-05-10

    The impact that unrecognized differences in the chemical patterns of Galactic globular clusters (GGCs) have on their relative age determinations is studied. The two most widely used relative age-dating methods, horizontal and vertical, together with the more recent relative MS-fitting method, were carefully analyzed on a purely theoretical basis. The BaSTI library was adopted to perform the present analysis. We find that relative ages derived using the horizontal and vertical methods are largely dependent on the initial He content and heavy element distribution. Unrecognized cluster-to-cluster chemical abundance differences can lead to an error in the derived relative ages as large as {approx}0.5 (or {approx}6 Gyr if an age of 12.8 Gyr is adopted for normalization) and even larger for some extreme cases. It is shown that the relative MS-fitting method is by far the age-dating technique for which undetected cluster-to-cluster differences in the He abundance have less impact. Present results are used in order to pose constraints on the maximum possible spread in the He and CNONa elements abundances on the basis of the estimates-taken from the literature-of the GGCs relative age dispersion obtained with the various relative age-dating techniques. Finally, it is shown that the age-metallicity relation found for young GGCs by the GC Treasury program is a real age sequence and cannot be produced by variations in the He and/or heavy element distribution.

  18. Ecological niche structure and rangewide abundance patterns of species.

    PubMed

    Martínez-Meyer, Enrique; Díaz-Porras, Daniel; Peterson, A Townsend; Yáñez-Arenas, Carlos

    2013-02-23

    Spatial abundance patterns across species' ranges have attracted intense attention in macroecology and biogeography. One key hypothesis has been that abundance declines with geographical distance from the range centre, but tests of this idea have shown that the effect may occur indeed only in a minority of cases. We explore an alternative hypothesis: that species' abundances decline with distance from the centroid of the species' habitable conditions in environmental space (the ecological niche). We demonstrate consistent negative abundance-ecological distance relationships across all 11 species analysed (turtles to wolves), and that relationships in environmental space are consistently stronger than relationships in geographical space. PMID:23134784

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

    USGS Publications Warehouse

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

    2011-01-01

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

  20. On the seismic age and heavy-element abundance of the Sun

    NASA Astrophysics Data System (ADS)

    Houdek, G.; Gough, D. O.

    2011-12-01

    We estimate the main-sequence age and heavy-element abundance of the Sun by means of an asteroseismic calibration of theoretical solar models using only low-degree acoustic modes from the BiSON. The method can therefore be applied also to other solar-type stars, such as those observed by the NASA satellite Kepler and the planned ground-based Danish-led Stellar Observations Network Group (SONG). The age, 4.60 ± 0.04 Gyr, obtained with this new seismic method, is similar to, although somewhat greater than, today's commonly adopted values, and the surface heavy-element abundance by mass, Zs= 0.0142 ± 0.0005, lies between the values quoted recently by Asplund et al. and by Caffau et al. We stress that our best-fitting model is not a seismic model, but a theoretically evolved model of the Sun constructed with 'standard' physics and calibrated against helioseismic data.

  1. LITHIUM ABUNDANCE AS A PREDICTOR OF MASS AND AGE IN SOLAR-ANALOG STARS

    SciTech Connect

    Li, T. D.; Bi, S. L.; Liu, K.; Tian, Z. J.; Ge, Z. S.; Chen, Y. Q.

    2012-02-20

    In order to estimate the mass and age of stars, we construct a grid of stellar models for eight solar-analog stars including diffusion and rotation-induced mixing for the given ranges of stellar mass, metallicity, and rotational rate. By combining stellar models with observational data including lithium abundance, we obtain more accurate estimations of mass and age for solar-analog stars. The results indicate that stars HIP 56948, HIP 73815, and HIP 78399 are three possible solar twins. Furthermore, we find that lithium depletion due to extra-mixing in solar analogs strongly depends on mass, metallicity, and rotational history. Therefore, lithium abundance can be used as a good constraint in stellar modeling.

  2. Microbial abundance and community structure in a melting alpine snowpack.

    PubMed

    Lazzaro, Anna; Wismer, Andrea; Schneebeli, Martin; Erny, Isolde; Zeyer, Josef

    2015-05-01

    Snowmelt is a crucial period for alpine soil ecosystems, as it is related to inputs of nutrients, particulate matter and microorganisms to the underlying soil. Although snow-inhabiting microbial communities represent an important inoculum for soils, they have thus far received little attention. The distribution and structure of these microorganisms in the snowpack may be linked to the physical properties of the snowpack at snowmelt. Snow samples were taken from snow profiles at four sites (1930-2519 m a.s.l.) in the catchment of the Tiefengletscher, Canton Uri, Switzerland. Microbial (Archaea, Bacteria and Fungi) communities were investigated through T-RFLP profiling of the 16S and 18S rRNA genes, respectively. In parallel, we assessed physical and chemical parameters relevant to the understanding of melting processes. Along the snow profiles, density increased with depth due to compaction, while other physico-chemical parameters, such as temperature and concentrations of DOC and soluble ions, remained in the same range (e.g. <2 mg DOC L(-1), 5-30 μg NH4 (+)-N L(-1)) in all samples at all sites. Along the snow profiles, no major change was observed either in cell abundance or in bacterial and fungal diversity. No Archaea could be detected in the snow. Microbial communities, however, differed significantly between sites. Our results show that meltwater rearranges soluble ions and microbial communities in the snowpack.

  3. Ecological niche structure and rangewide abundance patterns of species

    PubMed Central

    Martínez-Meyer, Enrique; Díaz-Porras, Daniel; Peterson, A. Townsend; Yáñez-Arenas, Carlos

    2013-01-01

    Spatial abundance patterns across species' ranges have attracted intense attention in macroecology and biogeography. One key hypothesis has been that abundance declines with geographical distance from the range centre, but tests of this idea have shown that the effect may occur indeed only in a minority of cases. We explore an alternative hypothesis: that species' abundances decline with distance from the centroid of the species' habitable conditions in environmental space (the ecological niche). We demonstrate consistent negative abundance–ecological distance relationships across all 11 species analysed (turtles to wolves), and that relationships in environmental space are consistently stronger than relationships in geographical space. PMID:23134784

  4. Age and Abundance Discrimination in Old Stellar Populations Using Mid-Ultraviolet Colors

    NASA Astrophysics Data System (ADS)

    Dorman, Ben; O'Connell, Robert W.; Rood, Robert T.

    2003-07-01

    The rest-frame mid-ultraviolet spectral region (2000-3200 Å) is important in analyzing the stellar populations of the ``red envelope'' systems observed at high redshifts. Here we explore the usefulness of the mid-UV for determining ages and abundances of old populations. We work with a theoretical set of low-resolution spectra and broadband colors because tests show that these are at present more realistic than high-resolution models. A mid-UV to optical/IR wavelength baseline provides good separation of population components because the main-sequence turnoff dominates the integrated light between 2500 and 4000 Å. Mid-UV spectral features are not sensitive to the dwarf/giant mixture in the population, unlike those in the optical region. We find a 6 mag difference in the mid-UV continuum level (normalized at V) over the metallicity range -1.5ages in the range 4-16 Gyr. Logarithmic derivatives of mid-UV colors with respect to age or metal abundance are 3-10 times larger than for the UBV region. Most of the spectral information on old populations therefore resides below 4000 Å. Measurement of a single mid-UV color is capable of placing a strong lower bound on the mean metallicity of an old population. We investigate the capability of UBV and mid-UV broadband colors to separately determine age and abundance, taking into account precision in the color measurements. We find that the mid-UV improves resolution in logt, logZ space by about a factor of 3 for a given observational precision. Contamination by hot, post-He flash evolutionary phases can seriously affect the mid-UV spectra of old populations. A simple estimate shows that contamination can reach over 80% in some cases. However, this is straightforward to remove as long as far-UV measurements are available. We find that extinction should have relatively small effects on parameters derived for old populations from the mid-UV. Finally, we show

  5. Constraining Stellar Population Models. I. Age, Metallicity and Abundance Pattern Compilation for Galactic Globular Clusters

    NASA Astrophysics Data System (ADS)

    Roediger, Joel C.; Courteau, Stéphane; Graves, Genevieve; Schiavon, Ricardo P.

    2014-01-01

    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

  6. Rare Earth Element Abundances and Pb-Pb Ages of Merrillite in Jinju H5 Chondrite: Implications to Shock Metamorphism

    NASA Astrophysics Data System (ADS)

    Goh, S.; Choi, B.-G.

    2016-08-01

    Jinju merrillite shows homogeneous REE abundances and relatively young Pb-Pb ages. Jinju H5 chondrite was probably neither equilibrated nor compacted prior to the impact and the shock made trace elements including REEs and U-Pb equilibrated.

  7. Diversity, abundance and community network structure in sporocarp-associated beetle communities of the central Appalachian Mountains.

    PubMed

    Epps, Mary Jane; Arnold, A Elizabeth

    2010-01-01

    Although arthropods are abundant and diverse in and on macrofungal sporocarps, their associations with fungi seldom have been described at a community level. We examined sporocarp-associated beetle communities in two primary sites in the Appalachian Mountains and foothills, assessing beetle diversity and abundance in relation to study site, sampling season (early vs. late summer), and sporocarp characteristics such as taxonomic position, dry mass and age. From 758 sporocarps representing >180 species we recovered 15404 adult beetles representing 72 species and 15 families, primarily Staphylinidae (> 98% of individuals and of 64% morphospecies). The probability of sporocarp colonization by beetles, beetle abundance and diversity differed among fungal species and were positively associated with sporocarp dry mass. Sporocarp age was positively correlated with beetle diversity and abundance (as measured in a focal species, Megacollybia platyphylla, Tricholomataceae), and its effects were independent of dry mass. Many beetle species were generalists, visiting a wide breadth of fungi in both the Agaricales and Polyporales; however, several beetle taxa showed evidence of specialization on particular fungal hosts. Host association data were used to examine the structure underlying sporocarp-beetle associations. Here we present the first evidence of nested community structure in the sporocarp-beetle interaction network. PMID:20648747

  8. Early-type galaxy archeology: Ages, abundance ratios, and effective temperatures from full-spectrum fitting

    SciTech Connect

    Conroy, Charlie; Graves, Genevieve J.; Van Dokkum, Pieter G.

    2014-01-01

    The stellar populations of galaxies hold vital clues to their formation histories. In this paper we present results based on modeling stacked spectra of early-type galaxies drawn from the Sloan Digital Sky Survey as a function of velocity dispersion, σ, from 90 km s{sup –1} to 300 km s{sup –1}. The spectra are of extremely high quality, with typical signal-to-noise ratio of 1000 Å{sup –1}, and a wavelength coverage of 4000 Å –8800 Å. Our population synthesis model includes variation in 16 elements from C to Ba, a two-component star formation history, the shift in effective temperature, Δ T {sub eff}, of the stars with respect to a solar metallicity isochrone, and the stellar initial mass function, among other parameters. In our approach we fit the full optical spectra rather than a select number of spectral indices and are able to, for the first time, measure the abundances of the elements V, Cr, Mn, Co, and Ni from the integrated light of distant galaxies. Our main results are as follows: (1) light-weighted stellar ages range from 6-12 Gyr from low to high σ; (2) [Fe/H] varies by less than 0.1 dex across the entire sample; (3) Mg closely tracks O, and both increase from ≈0.0 at low σ to ∼0.25 at high σ; Si and Ti show a shallower rise with σ, and Ca tracks Fe rather than O; (4) the iron peak elements V, Cr, Mn, and Ni track Fe, while Co tracks O, suggesting that Co forms primarily in massive stars; (5) C and N track O over the full sample and [C/Fe] and [N/Fe] exceed 0.2 at high σ; and (6) the variation in Δ T {sub eff} with total metallicity closely follows theoretical predictions based on stellar evolution theory. This last result is significant because it implies that we are robustly solving not only for the detailed abundance patterns but also the detailed temperature distributions (i.e., isochrones) of the stars in these galaxies. A variety of tests reveal that the systematic uncertainties in our measurements are probably 0.05 dex or

  9. Structurally Resolved Abundances and Depletions in the Rho OPH Cloud

    NASA Astrophysics Data System (ADS)

    Seab, C.

    1995-07-01

    The mechanism that determines the pattern of depletion ofelements in the interstellar medium has been a problem for along time. It is clear that some of the most refractoryelements such as Si, Fe, and Mg, are heavily depleted onto theinterstellar grains. On the other hand, some elements such asS and Zn are normally either undepleted or very lightlydepleted. The difference between the two cases is notunderstood. We propose to address this question with adetailed study of the depletion patterns in the Rho Ophiuchicloud. This study is strongly based on a combination of thecapabilities of two modern instruments: the GHRS for high-resolution UV data, and the Ultra High Resolution Facility(UHRF) of the AAT. This instrument has been used to obtain NaI line profiles in the Rho Oph cloud with a resolution ofR=1,000,000. The combination of these two types of data willbe used to resolve the velocity structure of the elementdepletions in the cloud.

  10. GLOBULAR CLUSTER ABUNDANCES FROM HIGH-RESOLUTION, INTEGRATED-LIGHT SPECTROSCOPY. III. THE LARGE MAGELLANIC CLOUD: Fe AND AGES

    SciTech Connect

    Colucci, Janet E.; Bernstein, Rebecca A.; McWilliam, Andrew E-mail: rab@ucolick.org E-mail: andy@ociw.edu

    2011-07-01

    In this paper, we refine our method for the abundance analysis of high-resolution spectroscopy of the integrated light of unresolved globular clusters (GCs). This method was previously demonstrated for the analysis of old (>10 Gyr) Milky Way (MW) GCs. Here, we extend the technique to young clusters using a training set of nine GCs in the Large Magellanic Cloud. Depending on the signal-to-noise ratio of the data, we use 20-100 Fe lines per cluster to successfully constrain the ages of old clusters to within a {approx}5 Gyr range, the ages of {approx}2 Gyr clusters to a 1-2 Gyr range, and the ages of the youngest clusters (0.05-1 Gyr) to a {approx}200 Myr range. We also demonstrate that we can measure [Fe/H] in clusters with any age less than 12 Gyr with similar or only slightly larger uncertainties (0.1-0.25 dex) than those obtained for old MW GCs (0.1 dex); the slightly larger uncertainties are due to the rapid evolution in stellar populations at these ages. In this paper, we present only Fe abundances and ages. In the next paper in this series, we present our complete analysis of {approx}20 elements for which we are able to measure abundances. For several of the clusters in this sample, there are no high-resolution abundances in the literature from individual member stars; our results are the first detailed chemical abundances available. The spectra used in this paper were obtained at Las Campanas with the echelle on the du Pont Telescope and with the MIKE spectrograph on the Magellan Clay Telescope.

  11. Longitudinal patterns in flathead catfish relative abundance and length at age within a large river: Effects of an urban gradient

    USGS Publications Warehouse

    Paukert, C.P.; Makinster, A.S.

    2009-01-01

    We investigated the spatial variation of flathead catfish (Pylodictis olivaris) relative abundance and growth in the 274 km long Kansas River to determine if population dynamics of catfish are related to urbanization. Electrofishing was conducted at 462 random sites throughout the river in summer, 2005-2006 to collect fish. Relative abundance of age 1 fish (???200mm), subadult (>200-400mm) and adult fish (>400 mm) ranged from 0.34 to 14.67 fish h-1, mean length at age 1 was 165 (range: 128-195) mm total length (TL) and mean length at age 3 was 376 mm TL (range: 293-419mm TL). The proportion of land use within 200 m of the river edge was between 0 and 0.54 urban. River reaches with high relative abundance of age 1 flathead catfish had high relative abundance of subadult and adult catfish. River reaches with fast flathead catfish growth to age 1 had fast growth to age 3. High urban land use and riprap in the riparian area were evident in river reaches near the heavily populated Kansas City and Topeka, Kansas, USA. Reaches with increased number of log jams and islands had decreased riparian agriculture. Areas of low urbanization had faster flathead catfish growth (r = 0.67, p = 0.005). Relative abundance of flathead catfish was higher in more agricultural areas (r = -0.57, p = 0.02). Changes in land use in riverine environments may alter population dynamics of a fish species within a river. Spatial differences in population dynamics need to be considered when evaluating riverine fish populations. Published in 2008 by John Wiley & Sons Ltd.

  12. Globular Cluster Abundances from High-resolution, Integrated-light Spectroscopy. III. The Large Magellanic Cloud: Fe and Ages

    NASA Astrophysics Data System (ADS)

    Colucci, Janet E.; Bernstein, Rebecca A.; Cameron, Scott A.; McWilliam, Andrew

    2011-07-01

    In this paper, we refine our method for the abundance analysis of high-resolution spectroscopy of the integrated light of unresolved globular clusters (GCs). This method was previously demonstrated for the analysis of old (>10 Gyr) Milky Way (MW) GCs. Here, we extend the technique to young clusters using a training set of nine GCs in the Large Magellanic Cloud. Depending on the signal-to-noise ratio of the data, we use 20-100 Fe lines per cluster to successfully constrain the ages of old clusters to within a ~5 Gyr range, the ages of ~2 Gyr clusters to a 1-2 Gyr range, and the ages of the youngest clusters (0.05-1 Gyr) to a ~200 Myr range. We also demonstrate that we can measure [Fe/H] in clusters with any age less than 12 Gyr with similar or only slightly larger uncertainties (0.1-0.25 dex) than those obtained for old MW GCs (0.1 dex) the slightly larger uncertainties are due to the rapid evolution in stellar populations at these ages. In this paper, we present only Fe abundances and ages. In the next paper in this series, we present our complete analysis of ~20 elements for which we are able to measure abundances. For several of the clusters in this sample, there are no high-resolution abundances in the literature from individual member stars; our results are the first detailed chemical abundances available. The spectra used in this paper were obtained at Las Campanas with the echelle on the du Pont Telescope and with the MIKE spectrograph on the Magellan Clay Telescope. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

  13. Evolution of the chemical element abundances with age in open clusters: The Hyades, Pleiades, Coma Berenices and M6

    NASA Astrophysics Data System (ADS)

    Kiliçoǧlu, T.; Monier, R.; Gebran, M.; Fossati, L.

    2014-12-01

    We compare the averaged photospheric abundances of A and F stars in open clusters of different ages: M6 (˜80 Myr), Pleiades (˜100 Myr), Coma Berenices (˜450 Myr), and the Hyades (˜800 Myr). The variation in the averaged abundances among F stars generally reflects the differences between the initial compositions of the clusters in their various birthplaces. The differences of the averaged chemical composition of A stars may also reveal the effects of radiative difussion for the stars of different ages. We also discuss the methods, resolutions and wavelength coverages of spectra and discrepancies in the derived microturbulent velocities among the various studies to check if these studies are comparable. We also present the pattern of mean abundances and metallicity for the M6 cluster determined by spectral analysis of GIRAFFE spectra acquired with the VLT, Paranal Observatory.

  14. Fingerprints of anomalous primordial Universe on the abundance of large scale structures

    SciTech Connect

    Baghram, Shant; Abolhasani, Ali Akbar; Firouzjahi, Hassan; Namjoo, Mohammad Hossein E-mail: abolhasani@ipm.ir E-mail: MohammadHossein.Namjoo@utdallas.edu

    2014-12-01

    We study the predictions of anomalous inflationary models on the abundance of structures in large scale structure observations. The anomalous features encoded in primordial curvature perturbation power spectrum are (a): localized feature in momentum space, (b): hemispherical asymmetry and (c): statistical anisotropies. We present a model-independent expression relating the number density of structures to the changes in the matter density variance. Models with localized feature can alleviate the tension between observations and numerical simulations of cold dark matter structures on galactic scales as a possible solution to the missing satellite problem. In models with hemispherical asymmetry we show that the abundance of structures becomes asymmetric depending on the direction of observation to sky. In addition, we study the effects of scale-dependent dipole amplitude on the abundance of structures. Using the quasars data and adopting the power-law scaling k{sup n{sub A}-1} for the amplitude of dipole we find the upper bound n{sub A} < 0.6 for the spectral index of the dipole asymmetry. In all cases there is a critical mass scale M{sub c} in which for M M{sub c}) the enhancement in variance induced from anomalous feature decreases (increases) the abundance of dark matter structures in Universe.

  15. Cooperation and age structure in spatial games.

    PubMed

    Wang, Zhen; Wang, Zhen; Zhu, Xiaodan; Arenzon, Jeferson J

    2012-01-01

    We study the evolution of cooperation in evolutionary spatial games when the payoff correlates with the increasing age of players (the level of correlation is set through a single parameter, α). The demographic heterogeneous age distribution, directly affecting the outcome of the game, is thus shown to be responsible for enhancing the cooperative behavior in the population. In particular, moderate values of α allow cooperators not only to survive but to outcompete defectors, even when the temptation to defect is large and the ageless, standard α=0 model does not sustain cooperation. The interplay between age structure and noise is also considered, and we obtain the conditions for optimal levels of cooperation.

  16. Effects of understory structure on the abundance, richness and diversity of Collembola (Arthropoda) in southern Brazil.

    PubMed

    Ribeiro-Troian, Vera R; Baldissera, Ronei; Hartz, Sandra M

    2009-01-01

    The purpose of this study was to investigate the effects of different landscape structures on the understory Collembola community. Four different forest physiognomies were compared: Pinus spp. plantation, Eucalyptus spp. plantation, Araucaria angustifolia plantation, and a remaining native Araucaria forest. Three areas containing two sampling units (25 mx2 m each) were selected in each forest physiognomy. Understory Collembola collection was done with a 1x1 m canvas sheet held horizontally below the vegetation, which was beaten with a 1 m long stick, seasonally from September 2003 to August 2004. We evaluated the influence of forest physiognomies on the abundance, richness and diversity of Collembola communities. It was also verified if the habitat structure of each physiognomy was associated with the composition of the Collembola community. A total number of 4,111 individuals were collected belonging to the families Entomobrydae and Tomocerida (Entomobryomorpha), and Sminthuridae (Symphypleona), and divided in 12 morphospecies. Pinus plantation presented the highest richness, abundance and diversity of Collembola and it was associated to diverse understory vegetation. The abundance of Entomobrydae and Sminthuridae was associated to the presence of bushes, while Tomoceridae abundance was associated to the presence of trees. The habitat structure, measured through understory vegetation density and composition, plays an important role on the determination of the structure and composition of the Collembola community.

  17. Age structure and income distribution policy.

    PubMed

    Von Weizsacker, R K

    1988-01-01

    The dependence of earnings on age is a firmly established empirical fact. A simple microeconomic model of educational choice, being consistent with this observation, is designed. The model lends itself readily to aggregation over individuals and age groups. Thus, relations can be set up between economic variables influencing the aggregate distribution of labor incomes and demographic variables determining the age structure of the population. The main results of the present study are: 1) overall earnings inequality is shown to be an increasing function of life expectancy and a decreasing function of fertility. 2) The effectiveness of redistributive policies is sensitive to the age composition. In particular, the inequality-reducing effect of a 1% income tax rise is shown to be smaller the older the population.

  18. Normal and aging hair biology and structure 'aging and hair'.

    PubMed

    Goodier, Molly; Hordinsky, Maria

    2015-01-01

    Much like an individual's hairstyle, hair fibers along the scalp see a number of changes over the course of one's lifetime. As the decades pass, the shine and volume synonymous with youthful hair may give way to thin, dull, and brittle hair commonly associated with aging. These changes are a result of a compilation of genetic and environmental elements influencing the cells of the hair follicle, specifically the hair follicle stem cells and melanocytes. Telomere shortening, decrease in cell numbers, and particular transcription factors have all been implicated in this process. In turn, these molecular alterations lead to structural modifications of the hair fiber, decrease in melanin production, and lengthening of the telogen phase of the hair cycle. Despite this inevitable progression with aging, there exists an array of treatments such as light therapy, minoxidil, and finasteride which have been designed to mitigate the effects of aging, particularly balding and thinning hair. Although each works through a different mechanism, all aim to maintain or potentially restore the youthful quality of hair.

  19. Normal and aging hair biology and structure 'aging and hair'.

    PubMed

    Goodier, Molly; Hordinsky, Maria

    2015-01-01

    Much like an individual's hairstyle, hair fibers along the scalp see a number of changes over the course of one's lifetime. As the decades pass, the shine and volume synonymous with youthful hair may give way to thin, dull, and brittle hair commonly associated with aging. These changes are a result of a compilation of genetic and environmental elements influencing the cells of the hair follicle, specifically the hair follicle stem cells and melanocytes. Telomere shortening, decrease in cell numbers, and particular transcription factors have all been implicated in this process. In turn, these molecular alterations lead to structural modifications of the hair fiber, decrease in melanin production, and lengthening of the telogen phase of the hair cycle. Despite this inevitable progression with aging, there exists an array of treatments such as light therapy, minoxidil, and finasteride which have been designed to mitigate the effects of aging, particularly balding and thinning hair. Although each works through a different mechanism, all aim to maintain or potentially restore the youthful quality of hair. PMID:26370639

  20. Diversity and abundance of dung beetles attracted to different ages of cow dung at Tasik Chini Biosphere Reserve, Pahang

    NASA Astrophysics Data System (ADS)

    Aruchunnan, Ganaswary; Foo, Ng Yong; Ling, Wee Suk; Hazmi, Izfa Riza

    2015-09-01

    The attractiveness of cow dung of different ages towards dung beetles (Coleoptera: Scarabaeidae: Scarabaeinae) was studied in Tasik Chini Biosphere Reserve from February to April 2014. A total of 1,371 individuals belonging to 29 species and 11 genera had successfully collected in traps baited with cow dung aged at 1, 3 and 5 days. Cow dung was highly attractive at first 24 hours, and its attractiveness greatly reduced at Day 3 and Day 5. The result shows significant differences in the means of abundance (F = 4.60, d f= 2 & 24, P = 0.02) and species richness (F = 15.13, df = 2 & 24, P = 5.6 × 10-5). Bray Curtis similarity index indicated high community similarity between trap captures on Day 3 and Day 5 (59.7 %) compare to Day 1 (15.1 %) that leads to an assumption that some species preferentially colonized fresh dung while some species prefer aged dung. Species Copris agnus, Onthophagus aphodiodes, O. rorarius, O. orientalis, O. rutilans, O. vulpes, Oniticellus tessellatus and Paragymnopleurus maurus were captured on Day-1, while O. peninsularis and O. sumaveiensis captured on Day-3 and Day-5. Among the 11 genera, Onthophagus species was found to be most abundant with 762 individuals representing 55.6 % of the total captures. The most abundant species was Sisyphus thoracicus with 524 individuals (38.2 %). The dung beetle fauna's species accumulation curve in Tasik Chini did not reach to an asymptote suggesting more sampling effort is needed.

  1. Purification, characterization and structural analysis of an abundant beta-1,3-glucanase from banana fruit.

    PubMed

    Peumans, W J; Barre, A; Derycke, V; Rougé, P; Zhang, W; May, G D; Delcour, J A; Van Leuven, F; Van Damme, E J

    2000-02-01

    An abundant, catalytically active beta-1,3-endoglucanase (EC 3.2.1. 39) has been isolated from the pulp of ripe bananas. Biochemical analysis of the purified protein, molecular modelling, and molecular cloning of the corresponding gene indicate that this banana enzyme closely resembles previously characterized plant beta-glucanases with respect to its amino-acid sequence, structure and biological activity. The results described in this paper demonstrate both the occurrence of an abundant active beta-1,3-endoglucanases in fruits and also readdress the question of the possible involvement of these enzymes in the ripening and/or softening process.

  2. Relation of age-0 largemouth bass abundance to hydrilla coverage and water level at Lochloosa and Orange Lakes, Florida

    USGS Publications Warehouse

    Tate, W.B.; Allen, M.S.; Myers, R.A.; Nagid, E.J.; Estes, J.R.

    2003-01-01

    Changes in electrofishing catch per hour (CPH) of age-0 largemouth bass Micropterus salmoides were examined in relation to aquatic macrophytes and seasonal water elevation at Lochloosa and Orange lakes, Florida, during the 1990s. At Lochloosa Lake, stepwise multiple regression revealed a significant positive relationship between the mean CPH of age-0 largemouth bass and the percentage of areal coverage by hydrilla Hydrilla verticallata. At Orange Lake, mean CPH was directly associated with the percentage of areal coverage by hydrilla and inversely related to summer water levels. Thus, the influence of vegetation on age-0 largemouth bass abundance was similar at both lakes, but the effects of water levels were not. Further investigations into the effects of fluctuations in water levels on age-0 largemouth bass in natural lakes are needed.

  3. Effects of river discharge on abundance and instantaneous growth of age-0 carpsuckers in the Oconee River, Georgia, USA

    USGS Publications Warehouse

    Peterson, Ronald C.; Jennings, C.A.

    2007-01-01

    The Oconee River in middle Georgia, U.S.A., has been regulated by the Sinclair Dam since 1953. Since then, the habitat of the lower Oconee River has been altered and the river has become more incised. The altered environmental conditions of the Oconee River may limit the success of various fish populations. Some obligate riverine fishes may be good indicator species for assessing river system integrity because they are intolerant to unfavourable conditions. For example, many sucker species require clean gravel for feeding and reproduction. Further, age-0 fishes are more vulnerable than adults to flow alterations because of their limited ability to react to such conditions. In this study, we investigated the relationship between abundance and growth of age-0 carpsuckers to river discharge in the Oconee River. A beach seine was used to collect age-0 carpsuckers (Carpiodes spp.) from littoral zones of the lower Oconee River from May through July of 1995 to 2001. Regression models were used to assess whether 12 river discharge categories (e.g. peak, low, seasonal flows) influenced age-0 carpsucker abundance or instantaneous growth. Our analysis indicated that abundance of age-0 carpsuckers was significantly negatively related to number of days river discharge was >85 m3 s-1(r2=0.61, p=0.04). Estimates of instantaneous growth ranged from 0.10 to 0.90. Instantaneous growth rates were significantly positively related to summer river discharge (r2=0.95, p<0.01). These results suggest that (1) moderate flows during spawning and rearing are important for producing strong-year classes of carpsuckers, and (2) river discharge is variable among years, with suitable flows for strong year-classes of carpsuckers occurring every few years. River management should attempt to regulate river discharge to simulate historic flows typical for the region when possible. Such an approach is best achieved when regional climatic conditions are considered.

  4. Goldeye, Hiodon alosoides, in Lake Oahe: abundance, age, growth, maturity, food, and the fishery, 1963-69

    USGS Publications Warehouse

    Miller, Grant L.; Nelson, William R.

    1974-01-01

    Reproductive success was relatively consistent, and adequate to maintain species abundance at a nearly constant level, during 1963-69. Both abundance and growth in length increased from the lower to the upper portion of the reservoir. In most characteristics -- growth in length, length-weight relation, age at maturity, and food -- goldeye in Lake Oahe were similar to those from other Missouri River impoundments. Experimental gill nets samples all lengths (range 80-460 mm; median, 320 mm) of goldeye, bottom trawls sampled mostly small fish, (median, 215 mm) and trap nets large ones (median, 345 mm). Commercial gill nets were highly size selective (median, 375 mm); fish of ages IV-VII made up 90% of the catch. Survival rates were 57 to 52% for ages II-X. Estimated survival rates for ages V-IX declined from 44 to 35% after the inception of the commercial fishery in 1966. The peak commercial catch was 151,432 kg (1.2 kg/hectare) in 1969. Unless recruitment declines, the population can support a fishery of that magnitude.

  5. Coronal Thermal Structure and Abundance of Super-Metal-Rich Late-Type Stars

    NASA Technical Reports Server (NTRS)

    Brickhouse, Nancy; Mushotzky, Richard F. (Technical Monitor)

    2002-01-01

    This report covers the NASA grant NAG5-9943 for Cycle 1 XMM Guest Observer Program. The project is entitled 'Coronal Thermal Structure and Abundances of Super-Metal-Rich Late-Type Stars.' This observation is for grating spectroscopy of 30 Ari, a late-type star with very high metallicity (about twice solar). The goal is to use extreme cases to help understand how abundances change from the photosphere to the corona. The target was obtained by XMM-Newton on 2001 January 16 for 28000 sec. Data processing could not proceed until last fall because the SAS RGS software did not work. A poster was presented at the conference 'New Visions of the X-ray Universe in the XMM-Newton and Chandra Era,' held in Noordwijk 26-30 November 2001. The paper was entitled,'Coronal Abundances and Thermal Structure of the Super-Metal-Rich Star 30 Ari,'. The poster presented analysis of EPIC and RGS data to determine the individual abundances from the star and the emission measure distribution as a function of temperature. Results were compared with previous results on this star by our team using ASCA data.

  6. Spatial variation in parasite abundance: evidence of geographical population structuring in southern garfish Hyporhamphus melanochir.

    PubMed

    Hutson, K S; Brock, E L; Steer, M A

    2011-01-01

    Southern garfish Hyporhamphus melanochir were examined for metazoan parasites from nine sites in three regions (Spencer Gulf, Gulf St Vincent and northern Kangaroo Island) in South Australia to document parasite assemblages, identify candidate species suitable for use as biological tags and investigate spatial variation in parasite abundance. Four ectoparasite and 10 endoparasite species were identified representing Cestoda, Trematoda, Monogenea, Nematoda, Acanthocephala, Copepoda and Isopoda. Lernaeenicus hemirhamphi, Micracanthorhynchina hemirhamphi, Mothocya halei and Philometra sp. were suggested for 'permanent' biological markers. Multivariate discriminant function analysis showed that most sites could be distinguished based on differences in parasite abundance. Four endoparasites (Conohelmins sp., Hysterothylacium sp., M. hemirhamphi and Philometra sp.) were most important for site characterization. Limited spatial variation in permanent endoparasite abundance among localities in northern Spencer Gulf provided evidence for a distinct northern Spencer Gulf population with little interregional mixing. In contrast, considerable spatial variation in permanent endoparasite abundance between localities sampled off Kangaroo Island implied limited local movement and suggested H. melanochir may comprise a metapopulation structure. These results largely align with recent evidence from otolith chemistry that indicates fine-scale geographical population structuring in South Australian waters. PMID:21235553

  7. High-precision abundances of Sc, Mn, Cu, and Ba in solar twins. Trends of element ratios with stellar age

    NASA Astrophysics Data System (ADS)

    Nissen, P. E.

    2016-09-01

    Aims: A previous study of correlations between element abundances and ages of solar twin stars in the solar neighborhood is extended to include Sc, Mn, Cu, and Ba to obtain new information on the nucleosynthetic history of these elements. Methods: HARPS spectra with S/N ≳ 600 are used to derive very precise (σ ~ 0.01 dex) differential abundances of Sc, Mn, Cu, and Ba for 21 solar twins and the Sun. The analysis is based on MARCS model atmospheres with parameters determined from the excitation and ionization balance of Fe lines. Stellar ages with internal errors less than 1 Gyr are obtained by interpolation in the log g - Teff diagram between isochrones based on the Aarhus Stellar Evolution Code. Results: For stars younger than 6 Gyr, [Sc/Fe], [Mn/Fe], [Cu/Fe], and [Ba/Fe] are tightly correlated with stellar age, which is also the case for the other elements previously studied; linear relations between [X/Fe] and age have χ^2red ˜ 1, and for most stars the residuals do not depend on elemental condensation temperature. For ages between 6 and 9 Gyr, the [X/Fe] - age correlations break down and the stars split up into two groups having respectively high and low [X/Fe] for the odd-Z elements Na, Al, Sc, and Cu. Conclusions: While stars in the solar neighborhood younger than ~ 6 Gyr were formed from interstellar gas with a smooth chemical evolution, older stars seem to have originated from regions enriched by supernovae with different neutron excesses. Correlations between abundance ratios and stellar age suggest that: (i) Sc is made in Type II supernovae along with the α-capture elements; (ii) the Type II to Ia yield ratio is about the same for Mn and Fe; (iii) Cu is mainly made by the weak s-process in massive stars; (iv) the Ba/Y yield ratio for asymptotic giant branch stars increases with decreasing stellar mass; (v) [Y/Mg] and [Y/Al] can be used as chemical clocks when determining ages of solar metallicity stars. Based on data products from observations made

  8. Deer herbivory reduces web-building spider abundance by simplifying forest vegetation structure

    PubMed Central

    Chips, Michael J.; Carson, Walter P.

    2016-01-01

    Indirect ecological effects are a common feature of ecological systems, arising when one species affects interactions among two or more other species. We examined how browsing by white-tailed deer (Odocoileus virginianus) indirectly affected the abundance and composition of a web-building spider guild through their effects on the structure of the ground and shrub layers of northern hardwood forests. We examined paired plots consisting of deer-free and control plots in the Allegheny Plateau region Pennsylvania and Northern Highlands region of Wisconsin. We recorded the abundance of seven types of webs, each corresponding to a family of web-building spiders. We quantified vegetation structure and habitat suitability for the spiders by computing a web scaffold availability index (WSAI) at 0.5 m and 1.0 m above the ground. At Northern Highlands sites, we recorded prey availability. Spider webs were twice as abundant in deer-free plots compared to control plots, while WSAI was 7–12 times greater in deerfree plots. Prey availability was lower in deer-free plots. With the exception of funnel web-builders, all spider web types were significantly more abundant in deer-free plots. Both deer exclusion and the geographic region of plots were significant predictors of spider community structure. In closed canopy forests with high browsing pressure, the low density of tree saplings and shrubs provides few locations for web-building spiders to anchor webs. Recruitment of these spiders may become coupled with forest disturbance events that increase tree and shrub recruitment. By modifying habitat structure, deer appear to indirectly modify arthropod food web interactions. As deer populations have increased in eastern North America over the past several decades, the effects of deer on web-building spiders may be widespread. PMID:27703868

  9. Global Patterns of Abundance, Diversity and Community Structure of the Aminicenantes (Candidate Phylum OP8)

    PubMed Central

    Farag, Ibrahim F.; Davis, James P.; Youssef, Noha H.; Elshahed, Mostafa S.

    2014-01-01

    We investigated the global patterns of abundance, diversity, and community structure of members of the Aminicenantes (candidate phylum OP8). Our aim was to identify the putative ecological role(s) played by members of this poorly characterized bacterial lineages in various ecosystems. Analysis of near full-length 16S rRNA genes identified four classes and eight orders within the Aminicenantes. Within 3,134 datasets comprising ∼1.8 billion high throughput-generated partial 16S rRNA genes, 47,351 Aminicenantes-affiliated sequences were identified in 913 datasets. The Aminicenantes exhibited the highest relative abundance in hydrocarbon-impacted environments, followed by marine habitats (especially hydrothermal vents and coral-associated microbiome samples), and aquatic, non-marine habitats (especially in terrestrial springs and groundwater samples). While the overall abundance of the Aminicenantes was higher in low oxygen tension as well as non-saline and low salinity habitats, it was encountered in a wide range of oxygen tension, salinities, and temperatures. Analysis of the community structure of the Aminicenantes showed distinct patterns across various datasets that appear to be, mostly, driven by habitat variations rather than prevalent environmental parameters. We argue that the detection of the Aminicenantes across environmental extremes and the observed distinct community structure patterns reflect a high level of intraphylum metabolic diversity and adaptive capabilities that enable its survival and growth in a wide range of habitats and environmental conditions. PMID:24637619

  10. Abundance, distribution and size structure of Diadema antillarum (Echinodermata: Diadematidae) in South Eastern Cuban coral reefs.

    PubMed

    Martín Blanco, F; González Sansón, G; Pina Amargós, F; Clero Alonso, L

    2010-06-01

    The 1983-1984 mass mortality event of Diadema antillarum affected more than 93% of the total Caribbean population. Although there are no records about the status of Diadema populations before and after die-off on Cuban reefs, anecdotal information suggests that populations were struck. We analyzed spatial variation in the abundance and size structure of D. antillarum in 22 reefs sites in Jardines de la Reina, from June 2004 to September 2005. Counts of Diadema were performed in five 30x2 m transects at each sampling site and sampling time, and test diameters were measured in September 2005 at the same fore reefs. Abundances were higher at reef crests (mean densities 0.08-2.18 ind./m2), while reef slope populations reached a maximum site level of 0.13 ind./m2 at only one site and showed values up to three orders of magnitude lower than those from reef crests. Highest abundance occurred at the west margin of major channels between keys where larval recruitment seems to be favored by local oceanographic features and facilitated by the abundance of Echinometra lucunter. The size frequency distribution of D. antillarum indicates that recruitment began to be noticeable three years before September 2005, suggesting these populations were depleted in the past and they are recovering now.

  11. Abundance, distribution and size structure of Diadema antillarum (Echinodermata: Diadematidae) in South Eastern Cuban coral reefs.

    PubMed

    Martín Blanco, F; González Sansón, G; Pina Amargós, F; Clero Alonso, L

    2010-06-01

    The 1983-1984 mass mortality event of Diadema antillarum affected more than 93% of the total Caribbean population. Although there are no records about the status of Diadema populations before and after die-off on Cuban reefs, anecdotal information suggests that populations were struck. We analyzed spatial variation in the abundance and size structure of D. antillarum in 22 reefs sites in Jardines de la Reina, from June 2004 to September 2005. Counts of Diadema were performed in five 30x2 m transects at each sampling site and sampling time, and test diameters were measured in September 2005 at the same fore reefs. Abundances were higher at reef crests (mean densities 0.08-2.18 ind./m2), while reef slope populations reached a maximum site level of 0.13 ind./m2 at only one site and showed values up to three orders of magnitude lower than those from reef crests. Highest abundance occurred at the west margin of major channels between keys where larval recruitment seems to be favored by local oceanographic features and facilitated by the abundance of Echinometra lucunter. The size frequency distribution of D. antillarum indicates that recruitment began to be noticeable three years before September 2005, suggesting these populations were depleted in the past and they are recovering now. PMID:20527467

  12. Physiological tolerances account for range limits and abundance structure in an invasive slug.

    PubMed

    Lee, Jennifer E; Janion, Charlene; Marais, Elrike; Jansen van Vuuren, Bettine; Chown, Steven L

    2009-04-22

    Despite the importance of understanding the mechanisms underlying range limits and abundance structure, few studies have sought to do so. Here we use a terrestrial slug species, Deroceras panormitanum, that has invaded a remote, largely predator-free, Southern Ocean island as a model system to do so. Across Marion Island, slug density does not conform to an abundant centre distribution. Rather, abundance structure is characterized by patches and gaps. These are associated with this desiccation-sensitive species' preference for biotic and drainage line habitats that share few characteristics except for their high humidity below the vegetation surface. The coastal range margin has a threshold form, rapidly rising from zero to high density. Slugs do not occur where soil-exchangeable Na values are higher than 3000 mg kg(-1), and in laboratory experiments, survival is high below this value but negligible above it. Upper elevation range margins are a function of the inability of this species to survive temperatures below an absolute limit of -6.4 degrees C, which is regularly exceeded at 200 m altitude, above which slug density declines to zero. However, the linear decline in density from the coastal peak is probably also a function of a decline in performance or time available for activity. This is probably associated with an altitudinal decline in mean annual soil temperature. These findings support previous predictions made regarding the form of density change when substrate or climatic factors set range limits.

  13. Physiological tolerances account for range limits and abundance structure in an invasive slug

    PubMed Central

    Lee, Jennifer E.; Janion, Charlene; Marais, Elrike; Jansen van Vuuren, Bettine; Chown, Steven L.

    2009-01-01

    Despite the importance of understanding the mechanisms underlying range limits and abundance structure, few studies have sought to do so. Here we use a terrestrial slug species, Deroceras panormitanum, that has invaded a remote, largely predator-free, Southern Ocean island as a model system to do so. Across Marion Island, slug density does not conform to an abundant centre distribution. Rather, abundance structure is characterized by patches and gaps. These are associated with this desiccation-sensitive species' preference for biotic and drainage line habitats that share few characteristics except for their high humidity below the vegetation surface. The coastal range margin has a threshold form, rapidly rising from zero to high density. Slugs do not occur where soil-exchangeable Na values are higher than 3000 mg kg−1, and in laboratory experiments, survival is high below this value but negligible above it. Upper elevation range margins are a function of the inability of this species to survive temperatures below an absolute limit of −6.4°C, which is regularly exceeded at 200 m altitude, above which slug density declines to zero. However, the linear decline in density from the coastal peak is probably also a function of a decline in performance or time available for activity. This is probably associated with an altitudinal decline in mean annual soil temperature. These findings support previous predictions made regarding the form of density change when substrate or climatic factors set range limits. PMID:19324817

  14. Biotic Stress Shifted Structure and Abundance of Enterobacteriaceae in the Lettuce Microbiome

    PubMed Central

    Erlacher, Armin; Cardinale, Massimiliano; Grube, Martin; Berg, Gabriele

    2015-01-01

    Lettuce cultivars are not only amongst the most popular vegetables eaten raw, they are also involved in severe pathogen outbreaks world-wide. While outbreaks caused by Enterobacteriaceae species are well-studied, less is known about their occurrence in natural environments as well as the impact of biotic stress. Here, we studied the ecology of the human health-relevant bacterial family Enterobacteriaceae and assessed the impact of biotic disturbances by a soil-borne phytopathogenic fungus and Gastropoda on their structure and abundance in mesocosm and pot experiments. Using a polyphasic approach including network analyses of 16S rRNA gene amplicon libraries, quantitative PCR and complementary fluorescence in situ hybridization (FISH) microscopy we found substantial yet divergent Enterobacteriaceae communities. A similar spectrum of 14 genera was identified from rhizo- and phyllospheres but the abundance of Enterobacteriaceae was on average 3fold higher in phyllosphere samples. Both stress factors shifted the bacterial community of the leaf habitat, characterized by increases of species abundance and diversity. For the rhizosphere, we observed significant structural shifts of Enterobacteriaceae communities but also a high degree of resilience. These results could be confirmed by FISH microscopy but it was difficult to visualize phyllosphere communities. Additional inoculation experiments with Escherichia coli as model revealed their presence below the wax layer as well as in the endosphere of leaves. The observed presence influenced by stress factors and the endophytic life style of Enterobacteriaceae on lettuce can be an important aspect in relation to human health. PMID:25714833

  15. Biotic stress shifted structure and abundance of Enterobacteriaceae in the lettuce microbiome.

    PubMed

    Erlacher, Armin; Cardinale, Massimiliano; Grube, Martin; Berg, Gabriele

    2015-01-01

    Lettuce cultivars are not only amongst the most popular vegetables eaten raw, they are also involved in severe pathogen outbreaks world-wide. While outbreaks caused by Enterobacteriaceae species are well-studied, less is known about their occurrence in natural environments as well as the impact of biotic stress. Here, we studied the ecology of the human health-relevant bacterial family Enterobacteriaceae and assessed the impact of biotic disturbances by a soil-borne phytopathogenic fungus and Gastropoda on their structure and abundance in mesocosm and pot experiments. Using a polyphasic approach including network analyses of 16S rRNA gene amplicon libraries, quantitative PCR and complementary fluorescence in situ hybridization (FISH) microscopy we found substantial yet divergent Enterobacteriaceae communities. A similar spectrum of 14 genera was identified from rhizo- and phyllospheres but the abundance of Enterobacteriaceae was on average 3fold higher in phyllosphere samples. Both stress factors shifted the bacterial community of the leaf habitat, characterized by increases of species abundance and diversity. For the rhizosphere, we observed significant structural shifts of Enterobacteriaceae communities but also a high degree of resilience. These results could be confirmed by FISH microscopy but it was difficult to visualize phyllosphere communities. Additional inoculation experiments with Escherichia coli as model revealed their presence below the wax layer as well as in the endosphere of leaves. The observed presence influenced by stress factors and the endophytic life style of Enterobacteriaceae on lettuce can be an important aspect in relation to human health. PMID:25714833

  16. Tillage Management and Seasonal Effects on Denitrifier Community Abundance, Gene Expression and Structure over Winter.

    PubMed

    Tatti, Enrico; Goyer, Claudia; Burton, David L; Wertz, Sophie; Zebarth, Bernie J; Chantigny, Martin; Filion, Martin

    2015-10-01

    Tillage effects on denitrifier communities and nitrous oxide (N2O) emissions were mainly studied during the growing season. There is limited information for the non-growing season, especially in northern countries where winter has prolonged periods with sub-zero temperatures. The abundance and structure of the denitrifier community, denitrification gene expression and N2O emissions in fields under long-term tillage regimes [no-tillage (NT) vs conventional tillage (CT)] were assessed during two consecutive winters. NT exerted a positive effect on nirK and nosZ denitrifier abundance in both winters compared to CT. Moreover, the two contrasting managements had an opposite influence on nirK and nirS RNA/DNA ratios. Tillage management resulted in different denitrifier community structures during both winters. Seasonal changes were observed in the abundance and the structure of denitrifiers. Interestingly, the RNA/DNA ratios were greater in the coldest months for nirK, nirS and nosZ. N2O emissions were not influenced by management but changed over time with two orders of magnitude increase in the coldest month of both winters. In winter of 2009-2010, emissions were mainly as N2O, whereas in 2010-2011, when soil temperatures were milder due to persistent snow cover, most emissions were as dinitrogen. Results indicated that tillage management during the growing season induced differences in denitrifier community structure that persisted during winter. However, management did not affect the active cold-adapted community structure.

  17. Influence of age of aggregates and prokaryotic abundance on glucose and leucine uptake by heterotrophic marine prokaryotes.

    PubMed

    Azúa, Iñigo; Unanue, Marian; Ayo, Begoña; Artolozaga, Itxaso; Iriberri, Juan

    2007-03-01

    The kinetics of glucose and leucine uptake in attached and free-living prokaryotes in two types of microcosms with different nutrient qualities were compared. Microcosm type M1, derived from unaltered seawater, and microcosm type M2, from phytoplankton cultures, clearly expressed different kinetic parameters (Vmax/cell and K' m). In aggregates with low cell densities (M1 microcosm), the attached prokaryotes benefited from attachment as reflected in the higher potential uptake rates, while in aggregates with high cell densities (M2 microcosm) differences in the potential uptake rates of attached and free-living prokaryotes were not evident. The aging process and the chemical changes in aggregates of M2 microcosms were followed for 15-20 days. The results showed that as the aggregates aged and prokaryotic abundance increased, attached prokaryotes decreased their potential uptake rate and their K' m for substrate. This suggests an adaptive response by attached prokaryotes when aggregates undergo quantitative and qualitative impoverishment.

  18. Relative abundance, age, growth, and fecundity of grubby Myoxocephalus aenaeus in Niantic River and Niantic Bay, Long Island Sound

    NASA Astrophysics Data System (ADS)

    Roseman, Edward F.; Tomichek, Christine A.; Maynard, Tracy; Burton, Jennifer A.

    2005-04-01

    Grubby ( Myoxocephalus aenaeus, Cottidae) is a common benthic fish of inshore waters and estuaries of eastern Long Island Sound; however, little information exists on their life history or population demographics. This study utilised a long-term data series (1976-2002) to assess grubby life history and population demographics and explores trends in the Niantic River and Niantic Bay populations. In addition, we examined the age, size, and fecundity of adult grubby in 2001-02 to determine the population characteristics in the region. Mean grubby catch per unit effort (CPUE) in Niantic Bay ranged from 0.4 per trawl in 1976 to 2.9 per trawl in 1984 while river CPUE ranged from 0.4 per trawl in 1977 to 7.6 per trawl in 1989. Catch of grubby in bottom trawls varied seasonally with highest CPUE occurring in winter. Highest entrainment of grubby larvae occurred in 2001 while the lowest entrainment observed was in 1991. Four age classes, 0+ through III+, were derived from otolith analysis (N = 51) although length frequency analysis suggested the possibility of older fish in the population. The total number of eggs in ovaries ranged from 286 to 16 451 for grubby (N = 64) between 52 mm and 155 mm TL. Results of this study indicated a decline in abundance of adult grubby over the 26-year period, possibly related to concurrent declines in eelgrass ( Zostera marina) abundance and/or increased water temperature.

  19. Relative abundance, age, growth, and fecundity of grubby Myoxocephalus aenaeus in Niantic River and Niantic Bay, Long Island Sound

    USGS Publications Warehouse

    Roseman, E.F.; Tomichek, C.A.; Maynard, T.; Burton, J.A.

    2005-01-01

    Grubby (Myoxocephalus aenaeus, Cottidae) is a common benthic fish of inshore waters and estuaries of eastern Long Island Sound; however, little information exists on their life history or population demographics. This study utilised a long-term data series (1976-2002) to assess grubby life history and population demographics and explores trends in the Niantic River and Niantic Bay populations. In addition, we examined the age, size, and fecundity of adult grubby in 2001-02 to determine the population characteristics in the region. Mean grubby catch per unit effort (CPUE) in Niantic Bay ranged from 0.4 per trawl in 1976 to 2.9 per trawl in 1984 while river CPUE ranged from 0.4 per trawl in 1977 to 7.6 per trawl in 1989. Catch of grubby in bottom trawls varied seasonally with highest CPUE occurring in winter. Highest entrainment of grubby larvae occurred in 2001 while the lowest entrainment observed was in 1991. Four age classes, 0+ through III+, were derived from otolith analysis (N = 51) although length frequency analysis suggested the possibility of older fish in the population. The total number of eggs in ovaries ranged from 286 to 16 451 for grubby (N = 64) between 52 mm and 155 mm TL. Results of this study indicated a decline in abundance of adult grubby over the 26-year period, possibly related to concurrent declines in eelgrass (Zostera marina) abundance and/or increased water temperature. ?? 2005 Elsevier B.V. All rights reserved.

  20. Setting firmer constraints on the evolution of the most massive, central galaxies from their local abundances and ages

    NASA Astrophysics Data System (ADS)

    Buchan, Stewart; Shankar, Francesco

    2016-10-01

    There is still much debate surrounding how the most massive, central galaxies in the local universe have assembled their stellar mass, especially the relative roles of in situ growth versus later accretion via mergers. In this paper, we set firmer constraints on the evolutionary pathways of the most massive central galaxies by making use of empirical estimates on their abundances and stellar ages. The most recent abundance matching and direct measurements strongly favour that a substantial fraction of massive galaxies with Mstar>3 × 1011 M⊙ reside at the centre of clusters with mass Mhalo>3 × 1013 M⊙. Spectral analysis supports ages >10 Gyr, corresponding to a formation redshift zform>2. We combine these two pieces of observationally based evidence with the mass accretion history of their host dark matter haloes. We find that in these massive haloes, the stellar mass locked up in the central galaxy is comparable to, if not greater than, the total baryonic mass at zform. These findings indicate that either only a relatively minor fraction of their present-day stellar mass was formed in situ at zform, or that these massive, central galaxies form in the extreme scenario where almost all of the baryons in the progenitor halo are converted into stars. Interestingly, the latter scenario would not allow for any substantial size growth since the galaxy's formation epoch either via mergers or expansion. We show our results hold irrespective of systematic uncertainties in stellar mass, abundances, galaxy merger rates, stellar initial mass function, star formation rate and dark matter accretion histories.

  1. Spatial and seasonal patterns in abundance and age-composition of Calanus finmarchicus in the Gulf of Maine and on Georges Bank: 1977 1987

    NASA Astrophysics Data System (ADS)

    Meise, C. J.; O'Reilly, J. E.

    ubiquitously very abundant (> 10 4/10 m 2), and diverged from September to December. C. finmarchicus stage distribution in the GB-GOM area was highly negatively correlated with mean water column temperature during the stratified season. This seemed more related to the hydrography of the region, which isolates warmer well mixed Georges Bank from the Gulf of Maine and the stratified areas on the Bank, than to temperature, because Calanus abundances decline on the Bank before water temperatures exceed their preferences. A large part of the spatial and seasonal variation in C. finmarchicus abundance and age structure appears to be tightly coupled to major hydrographic regimes and to major circulation patterns in the region. There was a sharp ecotone between well-mixed Georges Bank and the Gulf of Maine as defined by C. finmarchicus abundance patterns and life history distributions. The ecotone is present year-round but is most apparent during the stratified season (May-October), when thermohaline density gradients and the near-surface current jet along the northern flank are generally strongest. The Gulf of Maine had the highest abundances of C. finmarchicus, and lowest spatial and seasonal variation in the region, while tidally mixed Georges Banks displayed the opposite pattern. This indication of stable population centers in the Gulf of Maine would make it a major source of Calanus in the region, particularly during March-April. Distributional patterns also suggest a strong Calanus influence from Scotian Shelf water in northern Gulf of Maine and on the southern flank of Georges Bank.

  2. AGE-STRUCTURAL TRANSITION IN INDONESIA

    PubMed Central

    Kreager, Philip; Schröder-Butterfill, Elisabeth

    2016-01-01

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

  3. Verrucomicrobial community structure and abundance as indicators for changes in chemical factors linked to soil fertility.

    PubMed

    Navarrete, Acacio Aparecido; Soares, Tielle; Rossetto, Raffaella; van Veen, Johannes Antonie; Tsai, Siu Mui; Kuramae, Eiko Eurya

    2015-09-01

    Here we show that verrucomicrobial community structure and abundance are extremely sensitive to changes in chemical factors linked to soil fertility. Terminal restriction fragment length polymorphism fingerprint and real-time quantitative PCR assay were used to analyze changes in verrucomicrobial communities associated with contrasting soil nutrient conditions in tropical regions. In case study Model I ("Slash-and-burn deforestation") the verrucomicrobial community structures revealed disparate patterns in nutrient-enriched soils after slash-and-burn deforestation and natural nutrient-poor soils under an adjacent primary forest in the Amazonia (R = 0.819, P = 0.002). The relative proportion of Verrucomicrobia declined in response to increased soil fertility after slash-and-burn deforestation, accounting on average, for 4 and 2 % of the total bacterial signal, in natural nutrient-poor forest soils and nutrient-enriched deforested soils, respectively. In case study Model II ("Management practices for sugarcane") disparate patterns were revealed in sugarcane rhizosphere sampled on optimal and deficient soil fertility for sugarcane (R = 0.786, P = 0.002). Verrucomicrobial community abundance in sugarcane rhizosphere was negatively correlated with soil fertility, accounting for 2 and 5 % of the total bacterial signal, under optimal and deficient soil fertility conditions for sugarcane, respectively. In nutrient-enriched soils, verrucomicrobial community structures were related to soil factors linked to soil fertility, such as total nitrogen, phosphorus, potassium and sum of bases, i.e., the sum of calcium, magnesium and potassium contents. We conclude that community structure and abundance represent important ecological aspects in soil verrucomicrobial communities for tracking the changes in chemical factors linked to soil fertility under tropical environmental conditions. PMID:26184407

  4. High abundance of small zoobenthos around biogenic structures in tidal sediments of the Wadden Sea

    NASA Astrophysics Data System (ADS)

    Reise, K.

    1981-12-01

    On the tidal flats of the island of Sylt (eastern part of the North Sea) the quantity of micro- and meiofauna associated with shoots of seagrass (Zostera noltii), with infaunal bivalves (Macoma balthica), and with tubes and burrows of polychaetes (Pygospio elegans, Pectinaria koreni, Nereis diversicolor, Nereis virens, Arenicola marina) was found to add up to 5 to 33 % of the overall abundance. These structures, taken together, account for 10 to 50 % of the faunal abundance on an average tidal flat at Sylt. The quantitative effect of biogenic structures at the sediment surface (casts and funnels) is small compared to that of tubes and burrows penetrating the anaerobic subsurface layer. In providing stable oxic microenvironments these elite structures frequently bring together more individuals than occur in the entire reducing sediment below surface. Faunal composition of irrigated dwellings of large infauna is different from that of the oxic surface sediment. The common denominator of all elite structures of the subsurface is an oxic halo. Burrows without such a halo are unattractive. There is no evidence that owners of burrows prey on their smaller inmates.

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

    USGS Publications Warehouse

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

    2006-01-01

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

  6. Phytoplankton abundance and structural parameters of the critically endangered protected area Vaya Lake (Bulgaria)

    PubMed Central

    Dimitrova, Ralits; Nenova, Elena; Uzunov, Blagoy; Shishiniova, Maria; Stoyneva, Maya

    2014-01-01

    Vaya (Ramsar site, protected area and Natura 2000 site) is the biggest natural lake in Bulgaria and the shallowest Black Sea coastal lake, which during the last decades has undergone significant changes and was included as critically endangered in the Red List of Bulgarian Wetlands. Our studies were conducted during the summer and autumn months of three years – 2004–2006. The paper presents results on the phytoplankton abundance (numbers, biomass and carbon content) in combination with the indices of species diversity, evenness and dominance. Phytoplankton abundance was extremely high (average values of 1135 × 106 cells/L for the quantity and of 46 mg/L for the biomass) and increased in the end of the studied period (years 2005–2006), when decrease of species diversity and increase of the dominance index values were detected. The carbon content of the phytoplankton was at an average value of 9.7 mg/L and also increased from 2004 to 2006. Cyanoprokaryota dominated in the formation of the total carbon content of the phytoplankton, in its numbers (88%–97.8%), and in the biomass (62%–87.9%). All data on phytoplankton abundance and structural parameters in Vaya confirm the hypertrophic status of the lake and reflect the general negative trend in its development. PMID:26019571

  7. Activity, abundance and structure of ammonia-oxidizing microorganisms in plateau soils.

    PubMed

    Dai, Yu; Wu, Zhen; Zhou, Qiheng; Zhao, Qun; Li, Ningning; Xie, Shuguang; Liu, Yong

    2015-10-01

    Both ammonia-oxidizing archaea (AOA) and bacteria (AOB) can be involved in biotransformation of ammonia to nitrite in soil ecosystems. However, the distribution of AOA and AOB in plateau soils and influential factors remain largely unclear. In the present study, the activity, abundance and structure of ammonia oxidizers in different soils on the Yunnan Plateau were assessed using potential nitrification rates (PNRs), quantitative PCR assay and clone library analysis, respectively. Wide variation was found in both AOA and AOB communities in plateau soils. PNRs showed a significant positive correlation with AOB abundance. Both were determined by the ratio of organic carbon to nitrogen (C/N) and total phosphorous (TP). AOB could play a more important role in ammonia oxidation. AOB community diversity was likely affected by soil total nitrogen (TN) and total organic carbon (TOC) and was usually higher than AOA community diversity. Moreover, Nitrososphaera- and Nitrosospira-like organisms, respectively, were the dominant AOA and AOB in plateau soils. AOA community structure was likely shaped by TP and C/N, while AOB community structure was determined by pH.

  8. The effects of mass flow on the temperature and abundance structure of the solar transition region

    NASA Technical Reports Server (NTRS)

    Woods, D. T.; Holzer, Thomas E.

    1991-01-01

    The density and temperature structure of a multicomponent plasma consisting of electrons, protons, ionized helium, and a trace minor ion species are computed. The equations of force and energy balance for this model are developed and solved. It is found that in the case of downflows the minor ion temperature can be significantly hotter than the electron temperature, and significant abundance enhancements are possible due to the slowdown of the minor species from the effect of the thermal force. A simple physical picture of the source of the thermal force is given.

  9. Neighborhood Age Structure and its Implications for Health

    PubMed Central

    2006-01-01

    Age structure at the neighborhood level is rarely considered in contextual studies of health. However, age structure can play a critical role in shaping community life, the availability of resources, and the opportunities for social engagement—all factors that, research suggests, have direct and indirect effects on health. Age structure can be theorized as a compositional effect and as a contextual effect. In addition, the dynamic nature of age structure and the utility of a life course perspective as applied to neighborhood effects research merits attention. Four Chicago neighborhoods are summarized to illustrate how age structure varies across small space, suggesting that neighborhood age structure should be considered a key structural covariate in contextual research on health. Considering age structure implies incorporating not only meaningful cut points for important age groups (e.g., proportion 65 years and over) but attention to the shape of the distribution as well. PMID:16865558

  10. Mesh size effects on assessments of planktonic hydrozoan abundance and assemblage structure

    NASA Astrophysics Data System (ADS)

    Nogueira Júnior, Miodeli; Pukanski, Luis Eduardo de M.; Souza-Conceição, José M.

    2015-04-01

    The choice of appropriate mesh-size is paramount to accurately quantify planktonic assemblages, however there is no such information available for hydrozoans. Here planktonic hydrozoan abundance and assemblage structure were compared using 200 and 500 μm meshes at Babitonga estuary (S Brazil), throughout a year cycle. Species richness and Shannon-Wiener diversity were higher in the 200 μm mesh, while evenness was typically higher in the 500 μm. Assemblage structure was significantly different between meshes (PERMANOVA, P < 0.05; n = 72 pairs of samples) both regarding taxa and size composition. These discrepancies are due to significant underestimation of small hydromedusae by the coarse mesh, like Obelia spp., young Liriope tetraphylla, Podocoryna loyola and others. Yet, larger taxa like Eucheilota maculata and adult L. tetraphylla were more abundant in the coarse mesh on some occasions and others such as Blackfordia virginica and Muggiaea kochi were similarly represented in both meshes. Overall collection efficiency of the coarse mesh (CE500) was 14.4%, with monthly averages between 1.6% and 43.0%, in July (winter) and January (summer) respectively. Differences between the meshes were size-dependent; CE500 was ~ 0.3% for hydrozoans sizing < 0.5 mm, ~ 21% for those between 1 and 2 mm, ~ 56% for those between 2 and 4 mm, and nearly 100% for larger ones, reaching up to 312% for hydrozoans > 8 mm in October. These results suggest that both meshes have their drawbacks and the best choice would depend on the objectives of each study. Nevertheless species richness, total abundances and most taxa were better represented by the 200 μm mesh, suggesting that it is more appropriate to quantitatively sample planktonic hydrozoan assemblages.

  11. Effect of altitude and season on microbial activity, abundance and community structure in Alpine forest soils.

    PubMed

    Siles, José A; Cajthaml, Tomas; Minerbi, Stefano; Margesin, Rosa

    2016-03-01

    In the current context of climate change, the study of microbial communities along altitudinal gradients is especially useful. Only few studies considered altitude and season at the same time. We characterized four forest sites located in the Italian Alps, along an altitude gradient (545-2000 m a.s.l.), to evaluate the effect of altitude in spring and autumn on soil microbial properties. Each site in each season was characterized with regard to soil temperature, physicochemical properties, microbial activities (respiration, enzymes), community level physiological profiles (CLPP), microbial abundance and community structure (PLFA). Increased levels of soil organic matter (SOM) and nutrients were found at higher altitudes and in autumn, resulting in a significant increase of (soil dry-mass related) microbial activities and abundance at higher altitudes. Significant site- and season-specific effects were found for enzyme production. The significant interaction of the factors site and incubation temperature for soil microbial activities indicated differences in microbial communities and their responses to temperature among sites. CLPP revealed site-specific effects. Microbial community structure was influenced by altitudinal, seasonal and/or site-specific effects. Correlations demonstrated that altitude, and not season, was the main factor determining the changes in abiotic and biotic characteristics at the sites investigated.

  12. Simultaneous mapping of chemical abundances and magnetic field structure in Ap stars

    NASA Astrophysics Data System (ADS)

    Lueftinger, T.

    2014-11-01

    Magnetic A stars represent about 5 highly ordered, very stable and often very strong magnetic fields. They frequently show variations in both brightness and spectral line profiles that are synchronised to stellar rotation. Those variations are believed to be produced by atomic diffusion operating in the stellar atmospheres which have become stabilized by multi-kG magnetic fields. In recent years, with the development and application of the Doppler and magnetic-Doppler imaging techniques and the availability of high-precision spectroscopic and spectropolarimetric data, it has became possible to map the chemical abundances and magnetic field structures of Ap stars simultaneously and in increasing detail, based on full Stokes vector observations. I review the state-of-the-art understanding pf Ap star spots and their relation to magnetic fields, the development of Doppler and magnetic-Doppler imaging into one of the most powerful remote sensing methods for astrophysics, and the physics of Ap stars atmospheres that we can deduce from simultaneous mapping of magnetic field structure and chemical abundances.

  13. Soil biota community structure and abundance under agricultural intensification and extensification.

    PubMed

    Postma-Blaauw, Maria B; de Goede, Ron G M; Bloem, Jaap; Faber, Jack H; Brussaard, Lijbert

    2010-02-01

    Understanding the impacts of agricultural intensification and extensification on soil biota communities is useful in order to preserve and restore biological diversity in agricultural soils and enhance the role of soil biota in agroecosystem functioning. Over four consecutive years, we investigated the effects of agricultural intensification and extensification (including conversion of grassland to arable land and vice versa, increased and decreased levels of mineral fertilization, and monoculture compared to crop rotation) on major soil biota group abundances and functional diversity. We integrated and compared effects across taxonomic levels to identify sensitive species groups. Conversion of grassland to arable land negatively affected both abundances and functional diversity of soil biota. Further intensification of the cropping system by increased fertilization and reduced crop diversity exerted smaller and differential effects on different soil biota groups. Agricultural intensification affected abundances of taxonomic groups with larger body size (earthworms, enchytraeids, microarthropods, and nematodes) more negatively than smaller-sized taxonomic groups (protozoans, bacteria, and fungi). Also functional group diversity and composition were more negatively affected in larger-sized soil biota (earthworms, predatory mites) than in smaller-sized soil biota (nematodes). Furthermore, larger soil biota appeared to be primarily affected by short-term consequences of conversion (disturbance, loss of habitat), whereas smaller soil biota were predominantly affected by long-term consequences (probably loss of organic matter). Reestablishment of grassland resulted in increased abundances of soil biota groups, but since not all groups increased in the same measure, the community structure was not completely restored. We concluded that larger-sized soil biota are more sensitive to agricultural intensification than smaller-sized soil biota. Furthermore, since larger

  14. Structural health management for aging aircraft

    NASA Astrophysics Data System (ADS)

    Ikegami, Roy; Haugse, Eric D.

    2001-06-01

    An effective structural health management (SHM) system can be a useful tool for making aircraft fleet management decisions ranging from individual aircraft maintenance scheduling and usage restrictions to fleet rotation strategies. This paper discusses the end-user requirements for the elements and architecture of an effective SHM system for application to both military and commercial aging aircraft fleets. The elements discussed include the sensor systems for monitoring and characterizing the health of the structure, data processing methods for interpreting sensor data and converting it into useable information, and automated methods for erroneous data detection, data archiving and information dissemination. Current and past SHM technology development/maturation efforts in these areas at the Boeing Company will be described. An evolutionary technology development strategy is developed in which the technologies needed will be matured, integrated into a vehicle health management system, and benefits established without requiring extensive changes to the end-user's existing operation and maintenance infrastructure. Issues regarding the end-user customer acceptance of SHM systems are discussed and summarized.

  15. Differences in ecological structure, function, and native species abundance between native and invaded Hawaiian streams.

    PubMed

    Holitzki, Tara M; MacKenzie, Richard A; Wiegner, Tracy N; McDermid, Karla J

    2013-09-01

    Poeciliids, one of the most invasive species worldwide, are found on almost every continent and have been identified as an "invasive species of concern" in the United States, New Zealand, and Australia. Despite their global prevalence, few studies have quantified their impacts on tropical stream ecosystem structure, function, and biodiversity. Utilizing Hawaiian streams as model ecosystems, we documented how ecological structure, function, and native species abundance differed between poeciliid-free and poeciliid-invaded tropical streams. Stream nutrient yields, benthic biofilm biomass, densities of macroinvertebrates and fish, and community structures of benthic algae, macroinvertebrates, and fish were compared between streams with and without established poeciliid populations on the island of Hawai'i, Hawaii, USA. Sum nitrate (sigmaNO3(-) = NO3(-) + NO2(-)), total nitrogen, and total organic carbon yields were eight times, six times, and five times higher, respectively, in poeciliid streams than in poeciliid-free streams. Benthic biofilm ash-free dry mass was 1.5x higher in poeciliid streams than in poeciliid-free streams. Percentage contributions of chironomids and hydroptilid caddisflies to macroinvertebrate densities were lower in poeciliid streams compared to poeciliid-free streams, while percentage contributions of Cheumatopsyche analis caddisflies, Dugesia sp. flatworms, and oligochaetes were higher. Additionally, mean densities of native gobies were two times lower in poeciliid streams than in poeciliid-free ones, with poeciliid densities being approximately eight times higher than native fish densities. Our results, coupled with the wide distribution of invasive poeciliids across Hawaii and elsewhere in the tropics, suggest that poeciliids may negatively impact the ecosystem structure, function, and native species abundance of tropical streams they invade. This underscores the need for increased public awareness to prevent future introductions and for

  16. Indexing the relative abundance of age-0 white sturgeons in an impoundment of the lower Columbia River from highly skewed trawling data

    USGS Publications Warehouse

    Counihan, T.D.; Miller, A.I.; Parsley, M.J.

    1999-01-01

    The development of recruitment monitoring programs for age-0 white sturgeons Acipenser transmontanus is complicated by the statistical properties of catch-per-unit-effort (CPUE) data. We found that age-0 CPUE distributions from bottom trawl surveys violated assumptions of statistical procedures based on normal probability theory. Further, no single data transformation uniformly satisfied these assumptions because CPUE distribution properties varied with the sample mean (??(CPUE)). Given these analytic problems, we propose that an additional index of age-0 white sturgeon relative abundance, the proportion of positive tows (Ep), be used to estimate sample sizes before conducting age-0 recruitment surveys and to evaluate statistical hypothesis tests comparing the relative abundance of age-0 white sturgeons among years. Monte Carlo simulations indicated that Ep was consistently more precise than ??(CPUE), and because Ep is binomially rather than normally distributed, surveys can be planned and analyzed without violating the assumptions of procedures based on normal probability theory. However, we show that Ep may underestimate changes in relative abundance at high levels and confound our ability to quantify responses to management actions if relative abundance is consistently high. If data suggest that most samples will contain age-0 white sturgeons, estimators of relative abundance other than Ep should be considered. Because Ep may also obscure correlations to climatic and hydrologic variables if high abundance levels are present in time series data, we recommend ??(CPUE) be used to describe relations to environmental variables. The use of both Ep and ??(CPUE) will facilitate the evaluation of hypothesis tests comparing relative abundance levels and correlations to variables affecting age-0 recruitment. Estimated sample sizes for surveys should therefore be based on detecting predetermined differences in Ep, but data necessary to calculate ??(CPUE) should also be

  17. Biodiversity at the plant-soil interface: microbial abundance and community structure respond to litter mixing.

    PubMed

    Chapman, Samantha K; Newman, Gregory S

    2010-03-01

    The interactive effects of diversity in plants and microbial communities at the litter interface are not well understood. Mixtures of plant litter from different species often decompose differently than when individual species decompose alone. Previously, we found that litter mixtures of multiple conifers decomposed more rapidly than expected, but litter mixtures that included conifer and aspen litter did not. Understanding the mechanisms underlying these diversity effects may help explain existing anomalous decay dynamics and provide a glimpse into the elusive linkage between plant diversity and the fungi and bacteria that carry out decomposition. We examined the microbial communities on litter from individual plant species decomposing both in mixture and alone. We assessed two main hypotheses to explain how the decomposer community could stimulate mixed-litter decomposition above predicted rates: either by being more abundant, or having a different or more diverse community structure than when microbes decompose a single species of litter. Fungal, bacterial and total phospholipid fatty acid microbial biomass increased by over 40% on both conifer and aspen litter types in mixture, and microbial community composition changed significantly when plant litter types were mixed. Microbial diversity also increased with increasing plant litter diversity. While our data provide support for both the increased abundance hypothesis and the altered microbial community hypothesis, microbial changes do not translate to predictably altered litter decomposition and may only produce synergisms when mixed litters are functionally similar.

  18. Infer Metagenomic Abundance and Reveal Homologous Genomes Based on the Structure of Taxonomy Tree.

    PubMed

    Qiu, Yu-Qing; Tian, Xue; Zhang, Shihua

    2015-01-01

    Metagenomic research uses sequencing technologies to investigate the genetic biodiversity of microbiomes presented in various ecosystems or animal tissues. The composition of a microbial community is highly associated with the environment in which the organisms exist. As large amount of sequencing short reads of microorganism genomes obtained, accurately estimating the abundance of microorganisms within a metagenomic sample is becoming an increasing challenge in bioinformatics. In this paper, we describe a hierarchical taxonomy tree-based mixture model (HTTMM) for estimating the abundance of taxon within a microbial community by incorporating the structure of the taxonomy tree. In this model, genome-specific short reads and homologous short reads among genomes can be distinguished and represented by leaf and intermediate nodes in the taxonomy tree, respectively. We adopt an expectation-maximization algorithm to solve this model. Using simulated and real-world data, we demonstrate that the proposed method is superior to both flat mixture model and lowest common ancestry-based methods. Moreover, this model can reveal previously unaddressed homologous genomes.

  19. Helium abundance and ionization structure in the Orion nebula: radio recombination lines observations

    NASA Astrophysics Data System (ADS)

    Poppi, S.; Tsivilev, A. P.; Cortiglioni, S.; Palumbo, G. G. C.; Sorochenko, R. L.

    2007-03-01

    Results of the Ori A HII region mapping based on hydrogen (H), helium (He) and carbon (C) Radio Recombination lines (RRL) are presented. Observations were made with the same angular resolution (2') using the 32 m VLBI dish of Medicina (Italy, 22.4 GHz) and the Pushchino RT-22 dish (Russia, 36.5 GHz). The behaviour of the ionized helium abundance, y^+, with distance from the center shows that the He+ zone size is smaller than that of H^+. Such a behaviour is different for the core and for the envelope, as well as for different directions from the center. The helium abundance, N(He)/N(H)=10.0(± 0.8)%, is measured. Derived line radial velocities, their widths and y+ data support the well-known "blister-type" structure of this HII region. LTE electron temperatures (7800-9600 K) are also measured. Appendices (Figs. 15, 16 and Sect. 4.1 "Carbon RRLs") are only available in electronic form at http://www.aanda.org

  20. Neighborhood Age Structure and Support Networks.

    ERIC Educational Resources Information Center

    Ward, Russell A.; And Others

    Studies conducted in specifically age-segregated housing for older persons suggest that such age-homogeneous settings encourage networks of friendships and mutual assistance. Since patterns of age segregation exist within communities, such segregation may result in similar social benefits. Interviews (N=1,185) assessing social networks were…

  1. Millimeter observations of CS, HCO{sup +}, and CO toward five planetary nebulae: following molecular abundances with nebular age

    SciTech Connect

    Edwards, J. L.; Ziurys, L. M.; Cox, E. G.

    2014-08-20

    Millimeter and sub-millimeter observations of CO, CS, and HCO{sup +} have been conducted toward five planetary nebulae (PNe: K4-47, NGC 6537 (Red Spider), M2-48, NGC 6720 (Ring), and NGC 6853 (Dumbbell)), spanning an age range of 900-10,000 yr, using the Sub-Millimeter Telescope and the 12 m antenna of the Arizona Radio Observatory. The J = 5 → 4, J = 3 → 2, and J = 2 → 1 transitions of CS at 245, 147, and 98 GHz, as well as the J = 3 → 2 and J = 1 → 0 lines of HCO{sup +} at 268 and 89 GHz, were detected toward each source. At least three rotational transitions of CO have also been observed, including the J = 6 → 5 and J = 4 → 3 lines at 691 and 461 GHz. CS had not been definitively identified previously in PNe, and new detections of HCO{sup +} were made in four of the five nebulae. From a radiative transfer analysis of the CO and CS data, kinetic temperatures of T {sub K} ∼ 10-80 K and gas densities of n(H{sub 2}) ∼ 0.1-1 × 10{sup 6} cm{sup –3} were determined for the molecular material in these sources. Column densities for CO, CS, and HCO{sup +} were N {sub tot} ∼ 0.2-5 × 10{sup 16} cm{sup –2}, N {sub tot} ∼ 0.4-9 × 10{sup 12} cm{sup –2}, and N {sub tot} ∼ 0.3-5 × 10{sup 12} cm{sup –2}, respectively, with fractional abundances, relative to H{sub 2}, of f ∼ 0.4-2 × 10{sup –4}, f ∼ 1-4 × 10{sup –8}, and f ∼ 1 × 10{sup –8}, with the exception of M2-48, which had f(HCO{sup +}) ∼ 10{sup –7}. Overall, the molecular abundances do not significantly vary over a duration of 10,000 yr, in contrast to predictions of chemical models. The abundances reflect the remnant asymptotic giant branch shell material, coupled with photochemistry in the early PN phase. These observations also suggest that PNe eject substantial amounts of molecular material into the diffuse interstellar medium.

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

    ERIC Educational Resources Information Center

    Lawrence, Barbara S.

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

  3. Forest age influences oak insect herbivore community structure, richness, and density.

    PubMed

    Jeffries, June M; Marquis, Robert J; Forkner, Rebecca E

    2006-06-01

    Plant succession is one of many factors that may affect the composition and structure of herbivorous insect communities. However, few studies have examined the effect of forest age on the diversity and abundance of insect communities. If forest age influences insect diversity, then the schedule of timber harvest rotation may have consequent effects on biodiversity. The insect herbivore community on Quercus alba (white oak) in the Missouri Ozarks was sampled in a chronoseries, from recently harvested (2 yr) to old-growth (approximately 313 yr) forests. A total of nine sites and 39 stands within those sites were sampled in May and August 2003. Unique communities of plants and insects were found in the oldest forests (122-313 yr). Density and species richness of herbivores were positively correlated with increasing forest age in August but not in May. August insect density was negatively correlated with heat load index; in addition, insect density and richness increased over the chronoseries, but not on the sunniest slopes. Forest structural diversity (number of size classes) was positively correlated with forest age, but woody plant species richness was not. In sum, richness, density, and community structure of white oak insect herbivores are influenced by variation in forest age, forest structure, relative abundance of plant species, and abiotic conditions. These results suggest that time between harvests of large, long-lived, tree species such as white oak should be longer than current practice in order to maintain insect community diversity. PMID:16826990

  4. Fish passage and abundance around grade control structures on incised streams

    USGS Publications Warehouse

    Thomas, J.T.; Papanicolaou, A.N.; Pierce, C.L.; Dermisis, D.C.; Litvan, M.E.; Larson, C.J.

    2009-01-01

    This paper summarizes research from separate studies of fish passage over weirs (Larson et al., 2004; Litvan, 2006; Litvan, et al., 2008a-c) and weir hydraulics (Papanicolaou and Dermisis, 2006; Papanicolaou and Dermisis, in press). Channel incision in the deep loess region of western Iowa has caused decreased biodiversity because streams have high sediment loads, altered flow regimes, lost habitat, and lost lateral connectivity with their former floodplains. In-stream grade control structures (GCS) are built to prevent further erosion, protect infrastructure, and reduce sediment loads. However, GCS can have a detrimental impact on fisheries abundance and migration, biodiversity, and longitudinal connectivity. Fish mark-recapture studies were performed on stretches of streams with and without GCS. GCS with vertical or 1:4 (rise/run) downstream slopes did not allow fish migration, but GCS with slopes ??? 1:15 did. GCS sites were characterized by greater proportions of pool habitat, maximum depths, fish biomass, slightly higher index of biotic integrity (IBI) scores, and greater macroinvertebrate abundance and diversity than non-GCS sites. After modification of three GCS, IBI scores increased and fish species exhibiting truncated distributions before were found throughout the study area. Another study examined the hydraulic performance of GCS to facilitate unimpeded fish passage by determining the mean and turbulent flow characteristics in the vicinity of the GCS via detailed, non-intrusive field tests. Mean flow depth (Y) and velocity (V) atop the GCS were critical for evaluating GCS performance. Turbulent flow measurements illustrated that certain GCS designs cause sudden constrictions which form eddies large enough to disorient fish. GCS with slopes ??? 1:15 best met the minimum requirements to allow catfish passage of a flow depth of ??? 0.31 m and a mean flow velocity of ??? 1.22 m/s. ?? 2009 ASCE.

  5. Preovulatory Aging In Vivo and In Vitro Affects Maturation Rates, Abundance of Selected Proteins, Histone Methylation Pattern and Spindle Integrity in Murine Oocytes

    PubMed Central

    Demond, Hannah; Trapphoff, Tom; Dankert, Deborah; Heiligentag, Martyna; Grümmer, Ruth; Horsthemke, Bernhard; Eichenlaub-Ritter, Ursula

    2016-01-01

    Delayed ovulation and delayed fertilization can lead to reduced developmental competence of the oocyte. In contrast to the consequences of postovulatory aging of the oocyte, hardly anything is known about the molecular processes occurring during oocyte maturation if ovulation is delayed (preovulatory aging). We investigated several aspects of oocyte maturation in two models of preovulatory aging: an in vitro follicle culture and an in vivo mouse model in which ovulation was postponed using the GnRH antagonist cetrorelix. Both models showed significantly reduced oocyte maturation rates after aging. Furthermore, in vitro preovulatory aging deregulated the protein abundance of the maternal effect genes Smarca4 and Nlrp5, decreased the levels of histone H3K9 trimethylation and caused major deterioration of chromosome alignment and spindle conformation. Protein abundance of YBX2, an important regulator of mRNA stability, storage and recruitment in the oocyte, was not affected by in vitro aging. In contrast, in vivo preovulatory aging led to reduction in Ybx2 transcript and YBX2 protein abundance. Taken together, preovulatory aging seems to affect various processes in the oocyte, which could explain the low maturation rates and the previously described failures in fertilization and embryonic development. PMID:27611906

  6. Preovulatory Aging In Vivo and In Vitro Affects Maturation Rates, Abundance of Selected Proteins, Histone Methylation Pattern and Spindle Integrity in Murine Oocytes.

    PubMed

    Demond, Hannah; Trapphoff, Tom; Dankert, Deborah; Heiligentag, Martyna; Grümmer, Ruth; Horsthemke, Bernhard; Eichenlaub-Ritter, Ursula

    2016-01-01

    Delayed ovulation and delayed fertilization can lead to reduced developmental competence of the oocyte. In contrast to the consequences of postovulatory aging of the oocyte, hardly anything is known about the molecular processes occurring during oocyte maturation if ovulation is delayed (preovulatory aging). We investigated several aspects of oocyte maturation in two models of preovulatory aging: an in vitro follicle culture and an in vivo mouse model in which ovulation was postponed using the GnRH antagonist cetrorelix. Both models showed significantly reduced oocyte maturation rates after aging. Furthermore, in vitro preovulatory aging deregulated the protein abundance of the maternal effect genes Smarca4 and Nlrp5, decreased the levels of histone H3K9 trimethylation and caused major deterioration of chromosome alignment and spindle conformation. Protein abundance of YBX2, an important regulator of mRNA stability, storage and recruitment in the oocyte, was not affected by in vitro aging. In contrast, in vivo preovulatory aging led to reduction in Ybx2 transcript and YBX2 protein abundance. Taken together, preovulatory aging seems to affect various processes in the oocyte, which could explain the low maturation rates and the previously described failures in fertilization and embryonic development. PMID:27611906

  7. Vegetation in water-limited environments prioritizes photosynthesis over structural development when water is most abundant

    NASA Astrophysics Data System (ADS)

    Mccoll, K. A.; Konings, A. G.; Entekhabi, D.; Piles, M.; Alemohammad, S.

    2013-12-01

    Changes in rainfall variability due to climate change may shift some vegetated regions to water-limited conditions. It is unclear how this shift will affect vegetation phenology. To gain insight into the relationship between global vegetation phenology and water stress, we use global L-band scatterometer observations from NASA's Aquarius satellite to estimate RVI (Radar Vegetation Index; approximately, a measure of vegetation structure), global MODIS (MODerate Resolution Imaging Spectroradiometer) observations of NDVI (Normalized Difference Vegetation Index; approximately, a measure of vegetation function) and MERRA (Modern-Era Retrospective analysis for Research and Applications) reanalysis outputs of precipitation (P) and net radiation (Rn). We estimate the time of year at which each timeseries reaches a maximum, and observe consistent lags between peaks in NDVI and RVI over water-limited ecosystems that are not present in energy-limited ecosystems. We hypothesize that, in water-limited ecosystems, plants prioritize photosynthesis when water is most abundant and delay structural development until the dry season. In contrast, in energy-limited ecosystems, plants are able to both photosynthesize and generate woody biomass concurrently. The temporal variability of precipitation and net radiation, therefore, qualitatively influences the temporal dynamics of plant biomass allocation.

  8. Fluvial processes and local lithology controlling abundance, structure, and composition of mussel beds

    PubMed Central

    Vannote, Robin L.; Minshall, G. Wayne

    1982-01-01

    In the Salmon River Canyon, Idaho, the fresh-water pearl mussel, Margaritifera falcata, attains maximum density and age in river reaches where large block-boulders structurally stabilize cobbles and interstitial gravels. We hypothesize that block-boulders prevent significant bed scour during major floods, and these boulder-sheltered mussel beds, although rare, may be critical for population recruitment elsewhere within the river, especially after periodic flood scour of less protected mussel habitat. Mussel shells in Indian middens adjacent to these boulder-stabilized areas suggest that prehistoric tribes selectively exploited the high-density old-aged mussel beds. Locally, canyon reaches are aggrading with sand and gravel, and M. falcata is being replaced by Gonidea angulata. PMID:16593208

  9. Cytochrome c oxidase loses catalytic activity and structural integrity during the aging process in Drosophila melanogaster

    SciTech Connect

    Ren, Jian-Ching; Rebrin, Igor; Klichko, Vladimir; Orr, William C.; Sohal, Rajindar S.

    2010-10-08

    Research highlights: {yields} Cytochrome c oxidase loses catalytic activity during the aging process. {yields} Abundance of seven nuclear-encoded subunits of cytochrome c oxidase decreased with age in Drosophila. {yields} Cytochrome c oxidase is specific intra-mitochondrial site of age-related deterioration. -- Abstract: The hypothesis, that structural deterioration of cytochrome c oxidase (CcO) is a causal factor in the age-related decline in mitochondrial respiratory activity and an increase in H{sub 2}O{sub 2} generation, was tested in Drosophila melanogaster. CcO activity and the levels of seven different nuclear DNA-encoded CcO subunits were determined at three different stages of adult life, namely, young-, middle-, and old-age. CcO activity declined progressively with age by 33%. Western blot analysis, using antibodies specific to Drosophila CcO subunits IV, Va, Vb, VIb, VIc, VIIc, and VIII, indicated that the abundance these polypeptides decreased, ranging from 11% to 40%, during aging. These and previous results suggest that CcO is a specific intra-mitochondrial site of age-related deterioration, which may have a broad impact on mitochondrial physiology.

  10. Abundance of intrinsic structural disorder in the histone H1 subtypes.

    PubMed

    Kowalski, Andrzej

    2015-12-01

    The intrinsically disordered proteins consist of partially structured regions linked to the unstructured stretches, which consequently form the transient and dynamic conformational ensembles. They undergo disorder to order transition upon binding their partners. Intrinsic disorder is attributed to histones H1, perceived as assemblers of chromatin structure and the regulators of DNA and proteins activity. In this work, the comparison of intrinsic disorder abundance in the histone H1 subtypes was performed both by the analysis of their amino acid composition and by the prediction of disordered stretches, as well as by identifying molecular recognition features (MoRFs) and ANCHOR protein binding regions (APBR) that are responsible for recognition and binding. Both human and model organisms-animals, plants, fungi and protists-have H1 histone subtypes with the properties typical of disordered state. They possess a significantly higher content of hydrophilic and charged amino acid residues, arranged in the long regions, covering over half of the whole amino acid residues in chain. Almost complete disorder corresponds to histone H1 terminal domains, including MoRFs and ANCHOR. Those motifs were also identified in a more ordered histone H1 globular domain. Compared to the control (globular and fibrous) proteins, H1 histones demonstrate the increased folding rate and a higher proportion of low-complexity segments. The results of this work indicate that intrinsic disorder is an inherent structural property of histone H1 subtypes and it is essential for establishing a protein conformation which defines functional outcomes affecting on DNA- and/or partner protein-dependent cell processes.

  11. Stratigraphy of small shield volcanoes on Venus: Criteria for determining stratigraphic relationships and assessment of relative age and temporal abundance

    NASA Astrophysics Data System (ADS)

    Ivanov, Mikhail A.; Head, James W.

    2004-10-01

    . Fifteen fields (~11%) appear to be synchronous with regional plains, and eleven fields (~8%) postdate the plains. Nine fields (~6%) display ambiguous relationships with regional plains and their relative age is uncertain, and eight fields (~6%) represent unclear cases when fields are covered by crater-related materials or by young lava flows or are not in contact with regional plains. The results of our study provide evidence for a distinct change of volcanic style from the mode of formation of globally abundant small shields to the mode of emplacement of vast regional plains in many areas on Venus. This systematic change of volcanic style appears to be inconsistent with the ``nondirectional'' or quasi steady state character of the geologic record of Venus. Although individual small shields were formed throughout the majority of the visible geologic history of Venus, in the syn- and postregional plains time the small-shields style of volcanism was significantly reduced in abundance. The shield fields that predate regional plains do not display a strong tendency to form a single group or a few groups and can be found virtually in all places on Venus. We interpret this observation to mean that these shield fields were globally distributed before the emplacement of regional plains. This interpretation means that the shield fields embayed by regional plains represent exposures of a specific, globally widespread unit, shield plains (psh). In contrast, shield fields that postdate regional plains occur preferentially in the Beta-Atla-Themis region on Venus, well known for its concentration of relatively young volcanic and tectonic activity. The spatial association of relatively young fields with the large centers of young volcanism suggests a genetic link of these fields with the formation and development of the large-scale volcanic centers. The abrupt decrease of the number of shields that postdate the formation of shield plains (psh) strongly suggests a major change of the

  12. The abundant symmetry structure of hierarchies of nonlinear equations obtained by reciprocal links

    NASA Astrophysics Data System (ADS)

    Carillo, Sandra; Fuchssteiner, Benno

    1989-07-01

    Explicit computation for a Kawamoto-type equation shows that there is a rich associated symmetry structure for four separate hierarchies of nonlinear integrodifferential equations. Contrary to the general belief that symmetry groups for nonlinear evolution equations in 1+1 dimensions have to be Abelian, it is shown that, in this case, the symmetry group is noncommutative. Its semisimple part is isomorphic to the affine Lie algebra A(1)1 associated to sl(2,C). In two of the additional hierarchies that were found, an explicit dependence of the independent variable occurs. Surprisingly, the generic invariance for the Kawamoto-type equation obtained in Rogers and Carillo [Phys. Scr. 36, 865 (1987)] via a reciprocal link to the Möbius invariance of the singularity equation of the Kaup-Kupershmidt (KK) equation only holds for one of the additional hierarchies of symmetry groups. Thus the generic invariance is not a universal property for the complete symmetry group of equations obtained by reciprocal links. In addition to these results, the bi-Hamiltonian formulation of the hierarchy is given. A direct Bäcklund transformation between the (KK) hierarchy and the hierarchy of singularity equation for the Caudrey-Dodd-Gibbon-Sawada-Kotera equation is exhibited: This shows that the abundant symmetry structure found for the Kawamoto equation must exist for all fifth-order equations, which are known to be completely integrable since these equations are connected either by Bäcklund transformations or reciprocal links. It is shown that similar results must hold for all hierarchies emerging out of singularity hierarchies via reciprocal links. Furthermore, general aspects of the results are discussed.

  13. Variation in large-bodied fish-community structure and abundance in relation to water-management regime in a large regulated river.

    PubMed

    Haxton, T J; Findlay, C S

    2009-07-01

    Variation in life-history traits (growth, condition, mortality and recruitment) and relative abundance of 11 large-bodied fish species was investigated among three water-management regimes (unimpounded, run-of-the-river and winter reservoirs) in the large regulated Ottawa River, Canada. If waterpower management had an effect on fishes, then (1) would be expected community structuring among water-management regimes and (2) species with similar life-history traits should be affected in a similar manner. Large-bodied fish communities were assessed using two different standard index-netting techniques, one using trap nets and the other gillnets. Community structure could be discriminated based on species caught in nets using holographic neural networks (78.8% correct overall classification rate using trap nets and 76.0% using gillnets); therefore, water-management regimes affected community structure in the Ottawa River. Littoral zone benthivores were significantly lower in abundance (P < 0.001) or absent in winter reservoirs, whereas the abundance of planktivores or species that were planktivorous at young ages were significantly greater than in unimpounded river reaches. Growth, condition and mortality did not vary among reach types except smallmouth bass Micropterus dolomieu were in better condition in winter reservoirs than unimpounded reaches. Lake sturgeon Acipenser fulvescens recruitment was impaired in run-of-the-river reaches, whereas recruitment for other species that spawn in fast water was not affected.

  14. Constraining the Thermal Structure, Abundances, and Dynamics of the Exoplanet HD 209458b

    NASA Astrophysics Data System (ADS)

    Zellem, Robert; Griffith, Caitlin A.; Lewis, Nikole K.; Swain, Mark R.; Knutson, Heather A.

    2014-11-01

    HD 209458b has been extensively studied from the UV to IR as it is one of the brightest of the transiting exoplanets and has a large planet-to-star contrast. However its thermal profile and abundances remain constrained to at best 3 orders of magnitude (Line et al. 2014), largely due to a lack of spectral coverage. We expand HD 209458b’s wavelength coverage with ground and space observations. Our ground H, K, and L-band secondary eclipse spectroscopy, which explores HD 209458b’s emission mechanisms, is motivated by multiple detections of bright 3.3 μm emission on HD 189733b, resembling the CH4 ν3 band and potentially non-LTE fluorescence (Swain et al. 2010; Waldmann et al. 2012). CH4 fluorescence has previously been observed on Titan (Kim et al. 2000), Saturn, and Jupiter (Drossart et al. 1999; Brown et al. 2003), thereby likening exoplanets to their Solar System counterparts. We find that the hotter HD 209458b lacks to ~3σ a bright 3.3 μm feature as seen on HD 189733b, which is consistent with thermochemical equilibrium predictions (Moses et al. 2011). We measure HD 209458b’s longitudinally-varying thermal structure with Spitzer/IRAC full-orbit phase curve observations, and revise a previous 4.5 μm emission measurement downward by ˜35%. This change is significant because the high 4.5 and 5.8 μm brightness temperatures were interpreted as a thermal inversion (e.g., Line et al. 2014). While our 4.5 μm photometric emission point does not require an inversion, the shape of the phase curve, particularly the location and brightness temperature of the hot spot, suggests that HD 209458b has a dayside inversion. However the nightside is much cooler than predicted by a GCM. This discrepancy is potentially due to the GCM lacking quenching where vertical mixing outpaces reaction rates, causing increased CO and CH4 abundances at higher altitudes. We explore evidence for CH4 quenching with IRAC 3.6 micron data, which overlap the wings of the CH4 ν3 band, allowing

  15. Constraining the Thermal Structure, Abundances, and Dynamics of the Exoplanet HD 209458b

    NASA Astrophysics Data System (ADS)

    Zellem, Robert; Griffith, Caitlin Ann; Lewis, Nikole; Swain, Mark R.; Knutson, Heather

    2015-01-01

    HD 209458b has been extensively studied from the UV to IR as it is one of the brightest of the transiting exoplanets and has a large planet-to-star contrast. However its thermal profile and abundances remain constrained to at best 3 orders of magnitude (Line et al. 2014), largely due to a lack of spectral coverage. We expand HD 209458b's wavelength coverage with ground and space observations. Our ground H, K, and L-band secondary eclipse spectroscopy, which explores HD 209458b's emission mechanisms, is motivated by multiple detections of bright 3.3 μm emission on HD 189733b, resembling the CH4 ν3 band and potentially non-LTE fluorescence (Swain et al. 2010; Waldmann et al. 2012). CH4 fluorescence has previously been observed on Titan (Kim et al. 2000), Saturn, and Jupiter (Drossart et al. 1999; Brown et al. 2003), thereby likening exoplanets to their Solar System counterparts. We find that the hotter HD 209458b lacks to ~3σ a bright 3.3 μm feature as seen on HD 189733b, which is consistent with thermochemical equilibrium predictions (Moses et al. 2011). We measure HD 209458b's longitudinally-varying thermal structure with Spitzer/IRAC full-orbit phase curve observations, and revise a previous 4.5 μm emission measurement downward by ˜35%. This change is significant because the high 4.5 and 5.8 μm brightness temperatures were interpreted as a thermal inversion (e.g., Line et al. 2014). While our 4.5 μm photometric emission point does not require an inversion, the shape of the phase curve, particularly the location and brightness temperature of the hot spot, suggests that HD 209458b has a dayside inversion. However the nightside is much cooler than predicted by a GCM. This discrepancy is potentially due to the GCM lacking quenching where vertical mixing outpaces reaction rates, causing increased CO and CH4 abundances at higher altitudes. We explore evidence for CH4 quenching with IRAC 3.6 micron data, which overlap the wings of the CH4 ν3 band, allowing us to

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

    SciTech Connect

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

    1997-01-01

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

  17. Diversity, Abundance and Community Structure of Benthic Macro- and Megafauna on the Beaufort Shelf and Slope

    PubMed Central

    Nephin, Jessica; Juniper, S. Kim; Archambault, Philippe

    2014-01-01

    Diversity and community patterns of macro- and megafauna were compared on the Canadian Beaufort shelf and slope. Faunal sampling collected 247 taxa from 48 stations with box core and trawl gear over the summers of 2009–2011 between 50 and 1,000 m in depth. Of the 80 macrofaunal and 167 megafaunal taxa, 23% were uniques, present at only one station. Rare taxa were found to increase proportional to total taxa richness and differ between the shelf ( 100 m) where they tended to be sparse and the slope where they were relatively abundant. The macrofauna principally comprised polychaetes with nephtyid polychaetes dominant on the shelf and maldanid polychaetes (up to 92% in relative abundance/station) dominant on the slope. The megafauna principally comprised echinoderms with Ophiocten sp. (up to 90% in relative abundance/station) dominant on the shelf and Ophiopleura sp. dominant on the slope. Macro- and megafauna had divergent patterns of abundance, taxa richness ( diversity) and diversity. A greater degree of macrofaunal than megafaunal variation in abundance, richness and diversity was explained by confounding factors: location (east-west), sampling year and the timing of sampling with respect to sea-ice conditions. Change in megafaunal abundance, richness and diversity was greatest across the depth gradient, with total abundance and richness elevated on the shelf compared to the slope. We conclude that megafaunal slope taxa were differentiated from shelf taxa, as faunal replacement not nestedness appears to be the main driver of megafaunal diversity across the depth gradient. PMID:25007347

  18. Picoplankton and virioplankton abundance and community structure in Pearl River Estuary and Daya Bay, South China.

    PubMed

    Ni, Zhixin; Huang, Xiaoping; Zhang, Xia

    2015-06-01

    By using flow cytometry techniques, we investigated the abundance and composition of the heterotrophic prokaryotes, virioplankton and picophytoplankton community in the Pearl River Estuary and Daya Bay in the summer of 2012. We identified two subgroups of prokaryotes, high nucleic acid (HNA) and low nucleic acid (LNA), characterized by different nucleic acid contents. HNA abundance was significantly correlated with larger phytoplankton and Synechococcus (Syn) abundance, which suggested the important role of organic substrates released from primary producers on bacterial growth. Although LNA did not show any association with environmental variables, it was a vital component of the microbial community. In contrast to previous studies, the total virioplankton concentration had a poor relationship with nutrient availability. The positive relationship between large-sized phytoplankton abundance and the V-I population confirmed that V-I was a phytoplankton-infecting viral subgroup. Although the V-II group (bacteriophages) was dominant in the virioplankton community, it was not related with prokaryotic abundance, which indicated factors other than hosts controlling V-II abundance or the uncertainty of virus-host coupling. With respect to the picophytoplankton community, our results implied that river input exerted a strong limitation to Syn distribution in the estuary, while picoeukaryotes (Euk) were numerically less abundant and showed a quite different distribution pattern from that of Syn, and hence presented ecological properties distinct from Syn in our two studied areas.

  19. The spatial structure of hunter access determines the local abundance of forest elephants (Loxodonta africana cyclotis).

    PubMed

    Yackulic, Charles B; Strindberg, Samantha; Maisels, Fiona; Blake, Stephen

    2011-06-01

    In many previously remote regions in the world, increasing and often unregulated access is leading to dramatic increases in hunting pressure and declines in the densities of prey species, sometimes to the point of local extinction. Not surprisingly, numerous studies have found a correlation between the distance to the closest access point and prey densities. Here we hypothesized that, for many wide-ranging species, local abundances are reduced by hunting associated with multiple access points as opposed to just the closest access points. We also hypothesized that the distribution of hunter access determines both patterns of occupancy and abundance in occupied areas and that these two patterns (occupancy and abundance) respond to access at different spatial scales. Using data on the distribution of abundances of African forest elephant (Loxodonta africana cyclotis) in and around five national parks in Central Africa, we tested these hypotheses using a model comparison framework. We found that models including an index based on the distance to multiple roads outperformed models including other access-based covariates, including a model based on distance to the closest road only. We also found that models that allowed us to model occupancy and abundance separately outperformed simpler models. Occupancy responds to access at the same scale as previous estimates of average maximum displacement in the subspecies, while the scale of the response of abundance is more ambiguous, but appears to be greater. Lastly, we show that incorporating indices based on multiple access points and modeling abundance and occupancy has important practical consequences for our understanding of overall regional abundances and the distribution of abundances within regions.

  20. Nuclear Structure Data for the Present Age

    NASA Astrophysics Data System (ADS)

    Baglin, Coral M.

    2005-05-01

    The US Nuclear Data Program maintains and provides easy and free access to several comprehensive databases that assist scientists to sift through and assess the vast quantity of published nuclear structure and decay data. These databases are an invaluable asset for nuclear-science experimentalists and theorists alike, and the recommended values provided for nuclear properties such as decay modes, level energies and lifetimes, and radiation properties can also be of great importance to specialists in other fields such as medicine, geophysics, and reactor design. The Evaluated Nuclear Structure Data File (ENSDF) contains experimental nuclear structure data for all known nuclides, evaluated by the US nuclear data program evaluators in collaboration with a number of international data groups; the Nuclear Science Reference (NSR) database provides complementary bibliographic information; the Experimental Unevaluated Nuclear Data Listing (XUNDL) exists to enable rapid access to experimental nuclear-structure data compiled from the most recent publications (primarily in high-spin physics). This paper presents an overview of the nuclear structure and decay data available through these databases, with emphasis on recent and forthcoming additions to and presentations of the available material.

  1. Size, longevity and cancer: age structure

    PubMed Central

    2016-01-01

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

  2. Size, longevity and cancer: age structure.

    PubMed

    Wensink, Maarten J

    2016-09-14

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

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

    USGS Publications Warehouse

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

    2015-01-01

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

  4. Evaluation of aging degradation of structural components

    SciTech Connect

    Chopra, O.K.; Shack, W.J.

    1992-03-01

    Irradiation embrittlement of the neutron shield tank (NST) A212 Grade B steel from the Shippingport reactor, as well as thermal embrittlement of CF-8 cast stainless steel components from the Shippingport and KRB reactors, has been characterized. Increases in Charpy transition temperature (CTT), yield stress, and hardness of the NST material in the low-temperature low-flux environment are consistent with the test reactor data for irradiations at < 232{degrees}C. The shift in CTT is not as severe as that observed in surveillance samples from the High Flux Isotope Reactor (HFIR): however, it shows very good agreement with the results for HFIR A212-B steel irradiated in the Oak Ridge Research Reactor. The results indicate that fluence rate has not effect on radiation embrittlement at rates as low as 2 {times} 10{sup 8} n/cm{sup 2}{center_dot}s at the low operating temperature of the Shippingport NST, i.e., 55{degrees}C. This suggest that radiation damage in Shippingport NST and HFIR surveillance samples may be different because of the neutron spectra and/or Cu and Ni content of the two materials. Cast stainless steel components show relatively modest decreases in fracture toughness and Charpy-impact properties and a small increase in tensile strength. Correlations for estimating mechanical properties of cast stainless steels predict accurate or slightly conservative values for Charpy-impact energy, tensile flow stress, fracture toughness J-R curve, and J{sub IC} of the materials. The kinetics of thermal embrittlement and degree of embrittlement at saturation, i.e., the minimum impact energy achieved after long-term aging, were established from materials that were aged further in the laboratory. The results were consistent with the estimates. The correlations successfully predict the mechanical properties of the Ringhals 2 reactor hot- and crossover-leg elbows (CF-8M steel) after service of {approx}15 y.

  5. Evaluation of aging degradation of structural components

    SciTech Connect

    Chopra, O.K.; Shack, W.J.

    1992-03-01

    Irradiation embrittlement of the neutron shield tank (NST) A212 Grade B steel from the Shippingport reactor, as well as thermal embrittlement of CF-8 cast stainless steel components from the Shippingport and KRB reactors, has been characterized. Increases in Charpy transition temperature (CTT), yield stress, and hardness of the NST material in the low-temperature low-flux environment are consistent with the test reactor data for irradiations at < 232{degrees}C. The shift in CTT is not as severe as that observed in surveillance samples from the High Flux Isotope Reactor (HFIR): however, it shows very good agreement with the results for HFIR A212-B steel irradiated in the Oak Ridge Research Reactor. The results indicate that fluence rate has not effect on radiation embrittlement at rates as low as 2 {times} 10{sup 8} n/cm{sup 2}{center dot}s at the low operating temperature of the Shippingport NST, i.e., 55{degrees}C. This suggest that radiation damage in Shippingport NST and HFIR surveillance samples may be different because of the neutron spectra and/or Cu and Ni content of the two materials. Cast stainless steel components show relatively modest decreases in fracture toughness and Charpy-impact properties and a small increase in tensile strength. Correlations for estimating mechanical properties of cast stainless steels predict accurate or slightly conservative values for Charpy-impact energy, tensile flow stress, fracture toughness J-R curve, and J{sub IC} of the materials. The kinetics of thermal embrittlement and degree of embrittlement at saturation, i.e., the minimum impact energy achieved after long-term aging, were established from materials that were aged further in the laboratory. The results were consistent with the estimates. The correlations successfully predict the mechanical properties of the Ringhals 2 reactor hot- and crossover-leg elbows (CF-8M steel) after service of {approx}15 y.

  6. Communication Breakdown: The Impact of Ageing on Synapse Structure

    PubMed Central

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

    2014-01-01

    Impaired synaptic plasticity is implicated in the functional decline of the nervous system associated with ageing. Understanding the structure of ageing synapses is essential to understanding the functions of these synapses and their role in the ageing nervous system. In this review, we summarize studies on ageing synapses in vertebrates and invertebrates, focusing on changes in morphology and ultrastructure. We cover different parts of the nervous system, including the brain, the retina, the cochlea, and the neuromuscular junction. The morphological characteristics of aged synapses could shed light on the underlying molecular changes and their functional consequences. PMID:24495392

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

    PubMed

    Hong, S

    1982-01-01

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

  8. Effect of rabbit age on sperm chromatin structure.

    PubMed

    Gogol, P; Bochenek, M; Smorag, Z

    2002-04-01

    The aim of this study was to determine the relationship between the age of male rabbits and the sperm chromatin structure. The studies involved the semen of New Zealand White rabbits between 5 and 28 months of age. A flow cytometry and sperm chromatin structure assay (SCSA) method was used to determine chromatin structure. The results of cytometric chromatin structure assay suggested a relatively high stability of sperm chromatin in the rabbit. Between 6 and 16 months of age, the mean percentage of sperm with damaged chromatin was the lowest and ranged from 1.7 to 2.4%. Decreased sperm chromatin stability was found in ejaculates taken from male rabbits less than 5 months and more than 20 months of age. PMID:11975746

  9. Localizing Age-Related Individual Differences in a Hierarchical Structure

    ERIC Educational Resources Information Center

    Salthouse, Timothy A.

    2004-01-01

    Data from 33 separate studies were combined to create an aggregate data set consisting of 16 cognitive variables and 6832 different individuals who ranged between 18 and 95 years of age. Analyses were conducted to determine where in a hierarchical structure of cognitive abilities individual differences associated with age, gender, education, and…

  10. Emergence and Abundance of Western Corn Rootworm (Coleoptera: Chrysomelidae) in Bt Cornfields With Structured and Seed Blend Refuges.

    PubMed

    Hughson, Sarah A; Spencer, Joseph L

    2015-02-01

    To slow evolution of western corn rootworm (Diabrotica virgifera virgifera LeConte) resistance to Bt (Bacillus thuringiensis Berliner) corn hybrids, non-Bt "refuges" must be planted within or adjacent to Bt cornfields, allowing susceptible insects to develop without exposure to Bt toxins. Bt-susceptible adults from refuges are expected to find and mate with resistant adults that have emerged from Bt corn, reducing the likelihood that Bt-resistant offspring are produced. The spatial and temporal distribution of adults in four refuge treatments (20, 5, and 0% structured refuges and 5% seed blend) and adjacent soybean fields was compared from 2010 to 2012. Adult emergence (adults/trap/day) from refuge corn in structured refuge treatments was greater than that from Bt corn, except during the post-pollination period of corn phenology when emergence from refuge and Bt plants was often the same. Abundance of free-moving adults was greatest in and near refuge rows in structured refuge treatments during vegetative and pollination periods. By post-pollination, adult abundance became evenly distributed. In contrast, adult abundance in 5% seed blends and 0% refuges was evenly distributed, or nearly so, across plots throughout the season. The persistent concentration of adults in refuge rows suggests that structured refuge configurations may not facilitate the expected mixing of adults from refuge and Bt corn. Seed blends produce uniform distributions of adults across the field that may facilitate mating between Bt and refuge adults and ultimately delay the evolution of Bt resistance. PMID:26470111

  11. Aging management of containment structures in nuclear power plants

    SciTech Connect

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

    1994-12-31

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

  12. [Effects of macro-jellyfish abundance dynamics on fishery resource structure in the Yangtze River estuary and its adjacent waters].

    PubMed

    Shan, Xiu-Juan; Zhuang, Zhi-Meng; Jin, Xian-Shi; Dai, Fang-Qun

    2011-12-01

    Based on the bottom trawl survey data in May 2007 and May and June 2008, this paper analyzed the effects of the abundance dynamics of macro-jellyfish on the species composition, distribution, and abundance of fishery resource in the Yangtze River estuary and its adjacent waters. From May 2007 to June 2008, the average catch per haul and the top catch per haul of macro-jellyfish increased, up to 222.2 kg x h(-1) and 1800 kg x h(-1) in June 2008, respectively. The macro-jellyfish were mainly distributed in the areas around 50 m isobath, and not beyond 100 m isobath where was the joint front of the coastal waters of East China Sea, Yangtze River runoff, and Taiwan Warm Current. The main distribution area of macro-jellyfish in June migrated northward, as compared with that in May, and the highest catches of macro-jellyfish in May 2007 and May 2008 were found in the same sampling station (122.5 degrees E, 28.5 degrees N). In the sampling stations with higher abundance of macro-jellyfish, the fishery abundance was low, and the fishery species also changed greatly, mainly composed by small-sized species (Trachurus japonicus, Harpadon nehereus, and Acropoma japonicum) and pelagic species (Psenopsis anomala, Octopus variabilis) and Trichiurus japonicus, and P. anomala accounted for 23.7% of the total catch in June 2008. Larimichthys polyactis also occupied higher proportion of the total catch in sampling stations with higher macro-jellyfish abundance, but the demersal species Lophius litulon was not found, and a few crustaceans were collected. This study showed that macro-jellyfish had definite negative effects on the fishery community structure and abundance in the Yangtze River estuary fishery ecosystem, and further, changed the energy flow patterns of the ecosystem through cascading trophic interactions. Therefore, macro-jellyfish was strongly suggested to be an independent ecological group when the corresponding fishery management measures were considered.

  13. Age-structured optimal control in population economics.

    PubMed

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

    2004-06-01

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

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

    NASA Astrophysics Data System (ADS)

    Ducrot, Arnaut; Magal, Pierre; Ruan, Shigui

    2010-01-01

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

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

    USGS Publications Warehouse

    Link, W.A.; Royle, J. Andrew; Hatfield, J.S.

    2003-01-01

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

  16. A Long-Term Comparison of Yellowstone Cutthroat Trout Abundance and Size Structure in Their Historical Range in Idaho.

    SciTech Connect

    Meyer, Kevin A.; Schill, Daniel J.; Elle, F. Steven

    2002-05-23

    We compared estimates of population abundance and size structure for Yellowstone cutthroat trout Oncorhynchus clarki bouvieri obtained by electrofishing 77 stream segments across southeastern Idaho in the 1980s and again in 1999-2000 to test whether populations of Yellowstone cutthroat trout had changed. Sites sampled in the 1980s were relocated in 1999-2000 by using maps and photographs or by finding original site-boundary stakes, so that the same reach of stream was sampled during both periods. Abundance of Yellowstone cutthroat trout longer than 10 cm did not change, averaging 41 fish/100 m of stream during both the 1980s and 1999-2000. The proportion of the total catch of trout composed of Yellowstone cutthroat trout also did not change, averaging 82% in the 1980s and 78% in 1999-2000. At the 48 sites where size structure could be estimated for both periods, the proportion of Yellowstone cutthroat trout that were 10-20 cm long declined slightly (74% versus 66%), but the change was due entirely to the shift in size structure at the Teton River sites. The number of sites that contained rainbow trout O. mykiss or cutthroat trout 3 rainbow trout hybrids rose from 23 to 37, but the average proportion of the catch composed of rainbow trout and hybrids did not increase (7% in both the 1980s and 1999-2000). Although the distribution and abundance of Yellowstone cutthroat trout have been substantially reduced in Idaho over the last century, our results indicate that Yellowstone cutthroat trout abundance and size structure in Idaho have remained relatively stable at a large number of locations for the last 10-20 years. The expanding distribution of rainbow trout and hybrids in portions of the upper Snake River basin, however, calls for additional monitoring and active management actions.

  17. Aging and demographic plasticity in response to experimental age structures in honeybees (Apis mellifera L).

    PubMed

    Rueppell, Olav; Linford, Robyn; Gardner, Preston; Coleman, Jennifer; Fine, Kari

    2008-08-01

    Honeybee colonies are highly integrated functional units characterized by a pronounced division of labor. Division of labor among workers is mainly age-based, with younger individuals focusing on in-hive tasks and older workers performing the more hazardous foraging activities. Thus, experimental disruption of the age composition of the worker hive population is expected to have profound consequences for colony function. Adaptive demography theory predicts that the natural hive age composition represents a colony-level adaptation and thus results in optimal hive performance. Alternatively, the hive age composition may be an epiphenomenon, resulting from individual life history optimization. We addressed these predictions by comparing individual worker longevity and brood production in hives that were composed of a single age cohort, two distinct age cohorts, and hives that had a continuous, natural age distribution. Four experimental replicates showed that colonies with a natural age composition did not consistently have a higher life expectancy and/or brood production than the single cohort or double cohort hives. Instead, a complex interplay of age structure, environmental conditions, colony size, brood production, and individual mortality emerged. A general trade-off between worker life expectancy and colony productivity was apparent, and the transition from in-hive tasks to foraging was the most significant predictor of worker lifespan irrespective of the colony age structure. We conclude that the natural age structure of honeybee hives is not a colony-level adaptation. Furthermore, our results show that honeybees exhibit pronounced demographic plasticity in addition to behavioral plasticity to react to demographic disturbances of their societies.

  18. [Abundance, population structure and growth of the Atrina maura (Bivalvia: Pinnidae) in a tropical lagoon of the Mexican Pacific coast ].

    PubMed

    Ahumada-Sempoal, Miguel Angel; Serrano-Guzmán, Saúl Jaime; Ruiz-García, Noe

    2002-01-01

    The abundance, population structure, and growth of the Pen-shell Atrina maura in the Corralero-Alotengo tropical lagoon system in Oaxaca, Mexico, were studied from February to September of 1997. An abundance analysis showed significant temporal and spatial differences (Kruskal-Wallis, p < 0.001). Two spatial groups of abundance were found in the area, one from the mouth of the lagoon system to the middle of the Pen-shell bank, and the other between the middle of the Pen-shell bank and the head of the system. Three temporal periods of abundance were found (February-April-May; July-August; March-June-September). The distribution of population size showed that benthic recruitment of A. maura occurred from February to July. Length frequency of A. maura is commonly wide-ranging; nevertheless, in this study Pen-shell organisms with a valve length of 15 cm were frequently found. The growth rate length was 3.7 cm/month during the dry season (February to May), and 3.5 cm/month during the rainy season (June to September). Sex ratio was maintained at 1:1 from February to May, but males were dominant from June to August, and the minimum length for reproduction was registered at 10 cm valve length.

  19. Dissecting simulated disc galaxies - I. The structure of mono-age populations

    NASA Astrophysics Data System (ADS)

    Martig, Marie; Minchev, Ivan; Flynn, Chris

    2014-08-01

    We study seven simulated disc galaxies, three with a quiescent merger history, and four with mergers in their last 9 Gyr of evolution. We compare their structure at z = 0 by decomposing them into `mono-age populations' (MAPs) of stars within 500 Myr age bins. All studied galaxies undergo a phase of merging activity at high redshift, so that stars older than 9 Gyr are found in a centrally concentrated component, while younger stars are mostly found in discs. We find that most MAPs have simple exponential radial and vertical density profiles, with a scaleheight that typically increases with age. Because a large range of merger histories can create populations with simple structures, this suggests that the simplicity of the structure of mono-abundance populations observed in the Milky Way by Bovy et al. is not necessarily a direct indicator of a quiescent history for the Milky Way. Similarly, the anticorrelation between scalelength and scaleheight does not necessarily imply a merger-free history. However, mergers produce discontinuities between thin and thick disc components, and jumps in the age-velocity relation. The absence of a structural discontinuity between thin and thick disc observed in the Milky Way would seem to be a good indicator that no merger with a mass ratio larger than 1:15-1:10 occurred in the last 9 Gyr. Mergers at higher redshift might nevertheless be necessary to produce the thickest, hottest components of the Milky Way's disc.

  20. Structural and Functional Changes With the Aging Kidney.

    PubMed

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

    2016-01-01

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

  1. Effects of Chemical Abundances on the Structure and Dynamics of the Solar Atmosphere

    NASA Astrophysics Data System (ADS)

    Demarque, Pierre; Basu, S.; Robinson, F.; Hunter, C.; Kallinger, T.

    2008-05-01

    This paper presents a comparison between two three-dimensional radiative hydrodynamical (3D RHD) simulations of the solar outer layers using the Grevesse & Sauval (1998; GS98) and the Asplund, Grevesse & Sauval (2005; AGS05) mixtures, respectively. The AGS05 mixture is a revision of the solar abundance mixture using a model atmosphere based on the stratification and dynamics of a solar 3D RHD simulation performed with the GS98 mixture, using the code of Stein & Nordlund (1989, 1998). Our simulations use the same code, and physically realistic treatment of radiative opacities and equation of state as Robinson et al. (2003). A comparison between our GS98 and AGS05 3D simulations shows differences both in the mean vertical temperature gradient and in the turbulent velocity field in the line forming region of the solar atmosphere. The whole superadiabatic layer (SAL) in the AGS05 simulation, including its peak, is shifted outward with respect to the GS98 SAL. Turbulent velocities, critical for absorption line profile calculations, are larger in the AGS05 simulation by about 10%. Since opacities for the AGS05 mixture are lower than those for the GS98 mixture, the T-τ relations derived from the two simulations are different. At 5000K, τ obtained from the GS98 simulation is about 30% larger than that obtained from the AGS05 simulation. These results show the importance of preserving self consistency in the chemical abundances between the model atmosphere and the 3D HRD simulation. When deriving the solar abundances, one must iterate the chemical composition in the model atmosphere, and hence in the 3D simulation on which the atmosphere is based. This research was supported in part by NASA/ATP grant NAG5-13299 (PD and FR) and NSF grant ATM 0348837 to SB.

  2. Moist convection and the vertical structure and water abundance of Jupiter's atmosphere

    NASA Technical Reports Server (NTRS)

    Del Genio, Anthony D.; Mcgrattan, Kevin B.

    1990-01-01

    The cumulative effects of an ensemble of moist convective plumes on a conditionally unstable atmosphere are predicted by a model of moist convection on Jupiter in which the heating/cooling and drying/moistening of the environment occur through (1) compensating subsidence, (2) detrainment of updraft air at cloud tops, and (3) the evaporation and melting of falling condensate. Parahydrogen is transported as a passive tracer. Pure moist convective, mixed moist-dry convective, and primarily dry convective regimes are possible, depending on the assumed deep-water abundance, efficiency of condensate evaporation, and initial temperature profile.

  3. Structural Aging Program approach to providing an improved basis for aging management of safety-related concrete structures

    SciTech Connect

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

    1993-11-01

    The Structural Aging (SAG) Program is being conducted at the Oak Ridge National Laboratory (ORNL) for the United States Nuclear Regulatory Commission (USNRC). The SAG Program is addressing the aging management of safety-related concrete structures in nuclear power plants for the purpose of providing improved technical bases for their continued service. The program is organized into four tasks: Program Management, Materials Property Data Base, Structural Component Assessment/Repair Technologies, and Quantitative Methodology for Continued Service Determinations. Objectives and a summary of recent accomplishments under each of these tasks are presented.

  4. Nematode diversity, abundance and community structure 50 years after the formation of the volcanic island of Surtsey

    NASA Astrophysics Data System (ADS)

    Ilieva-Makulec, K.; Bjarnadottir, B.; Sigurdsson, B. D.

    2014-10-01

    The soil nematode fauna can give important insights into soil development and other habitat changes that occur during primary succession. We investigated the generic composition, density, distribution and community structure of nematodes 50 years after the formation of a pristine volcanic island, Surtsey, Iceland. Part of the island has received additional nutrient inputs from seagulls breeding there since 1985, while the reminder has been much less affected and is at present found at a different successional sere. In total, 25 genera of nematodes were identified, of which 14 were reported on Surtsey for the first time. Nematode communities were more diverse in the more infertile area outside the gull colony, where 24 genera were found, compared to 18 inside. The trophic structure of the nematode communities showed relatively higher abundance of fungal feeders in the infertile areas, but relatively more bacterial- and plant-feeders inside the colony. Nematode abundance in surface soil was, however, significantly higher within the gull colony, with 16.7 ind. cm-2 compared to 3.6 ind. cm-2 outside. A multivariate analysis indicated that the nematode abundance and distribution on Surtsey were most strongly related to the soil C : N ratio, soil acidity, plant cover and biomass, soil temperature and soil depth.

  5. Analysis of the c-src gene product structure, abundance, and protein kinase activity in human neuroblastoma and glioblastoma cells.

    PubMed

    O'Shaughnessy, J; Deseau, V; Amini, S; Rosen, N; Bolen, J B

    1987-01-01

    We have compared in different human neuroblastoma cell lines and human glioblastoma cells the expression level, structure, and tyrosine-specific protein kinase activity of pp60c-src. Our results show that not all human neuroblastoma cell lines express pp60c-src molecules with amino-terminal structural alterations. In neuroblastoma cells which possess pp60c-src with altered gel migration, the diminished polyacrylamide gel mobility of pp60c-src was found not to be dependent upon amino-terminal phosphorylations since extensive treatment of these molecules with phosphatase did not significantly change their gel migration properties. Similar differences in gel migration were observed when RNA from the various neuroblastoma and glioblastoma cells was translated in vitro using either rabbit reticulocyte or wheat germ lysates. White the level of c-src mRNA in the different cells analyzed was found to be similar, the abundance of pp60c-src in these same cells was found to vary by as much as 12-fold. This suggests that the abundance of pp60c-src in human neuroendocrine tumors is regulated through post-transcriptional and/or post-translational events which may be related to the stage of neuronal differentiation of the cells. Based upon determination of pp60c-src abundance by immunoblot analysis, we demonstrate that pp60c-src molecules derived from human neuroblastoma and glioblastoma cells have very similar in vitro protein kinase activities.

  6. Effects of Flow on Structure and Abundances in Multispecies Solar Coronal Loops

    NASA Astrophysics Data System (ADS)

    Lenz, Dawn D.

    2004-03-01

    We investigate the effects of large-scale bulk flows on coronal abundances using a multispecies numerical model. The model assumes that electrons, protons, and helium are in thermal equilibrium and constitute the bulk of the coronal plasma. Thermal diffusion and Coulomb friction are included. Temperature profiles for the bulk component and for each ion species are assumed, so the model reduces to a solution of mass and force balance for each component. We further assume that the bulk component has an upward bulk velocity at the base, and that ion flow speeds along field lines are negligible relative to the bulk flow. Coulomb coupling of the electrons and ions induces drag that counteracts the tendency of the ions to gravitationally settle. In regions of small ∇T, such as the outer regions of the corona, Coulomb drag is the only significant force counteracting gravitational settling in this model. We find that relatively modest bulk flows of tens of km s-1 can enhance ion abundances by 2-3 orders of magnitude over their values in low- or no-flow cases.

  7. Abundance and structure of microbial loop components (bacteria and protists) in lakes of different trophic status.

    PubMed

    Ryszard, Chrost J; Tomasz, Adamczewski; Kalinowska, Krystyna; Skowronska, Agnieszka

    2009-09-01

    The abundance, biomass, size distribution, and taxonomic composition of bacterial and protistan (heterotrophic and autotrophic nanoflagellates and ciliates) communities were investigated in six lakes of Masurian Lake District (north-eastern Poland) differing in trophic state. Samples were taken from the trophogenic water layer during summer stratification periods in the years of 2004 and 2006. Image analysis techniques with fluorescent in situ hybridization (FISH) as well as [3H]-methyl-thymidine incorporation methods were applied to analyze differences in the composition and activity of bacterial communities. The greatest differences in trophic parameters were found between the humic lake and remaining non-humic ones. The same bacterial and heterotrophic nanoflagellate (HNF) cell size classes dominated in all the studied lakes. However, distinct increases in the contributions of large bacterial (>1.0 microm) and HNF (>10 microm) cells were observed in eutrophic lakes. The bacterial community was dominated by the beta-Proteobacteria group, which accounted for 27% of total DAPI counts. Ciliate communities were largely composed of Oligotrichida. Positive correlations between bacteria and protists, as well as between nanoflagellates (both heterotrophic and autotrophic) and ciliates, suggest that concentrations of food sources may be important in determining the abundance of protists in the studied lakes.

  8. The lumbar extradural structure changes with increasing age.

    PubMed

    Igarashi, T; Hirabayashi, Y; Shimizu, R; Saitoh, K; Fukuda, H; Mitsuhata, H

    1997-02-01

    We have examined the extradural space using a flexible extraduroscope in 74 patients undergoing extradural anaesthesia at the L2-3 interspace. Extraduroscopy showed that the extradural space becomes widely patent and the fatty tissue in the extradural space diminishes with increasing age. We postulate that these age-related structural changes may affect the spread of local anaesthetic in the extradural space. PMID:9068330

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

    SciTech Connect

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

    1996-03-01

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

  10. Exploring the vertical age structure of the Galactic disc

    NASA Astrophysics Data System (ADS)

    Casagrande, Luca

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

  11. Exploring the vertical age structure of the Galactic disc

    NASA Astrophysics Data System (ADS)

    Casagrande, Luca; Silva Aguirre, Victor; Schlesinger, Katharine J.; Stello, Dennis; Huber, Daniel; Serenelli, Aldo; Schoenrich, Ralph; Asplund, Martin; Feltzing, Sofia

    2015-08-01

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

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

    PubMed

    Koval'skiĭ, G B

    1984-12-01

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

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

    PubMed Central

    Angel, Ronald J.

    2014-01-01

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

  14. Age or stage structure? A comparison of dynamic outcomes from discrete age- and stage-structured population models.

    PubMed

    Wikan, Arild

    2012-06-01

    Discrete stage-structured density-dependent and discrete age-structured density-dependent population models are considered. Regarding the former, we prove that the model at hand is permanent (i.e., that the population will neither go extinct nor exhibit explosive oscillations) and given density dependent fecundity terms we also show that species with delayed semelparous life histories tend to be more stable than species which possess precocious semelparous life histories. Moreover, our findings together with results obtained from other stage-structured models seem to illustrate a fairly general ecological principle, namely that iteroparous species are more stable than semelparous species. Our analysis of various age-structured models does not necessarily support the conclusions above. In fact, species with precocious life histories now appear to possess better stability properties than species with delayed life histories, especially in the iteroparous case. We also show that there are dynamical outcomes from semelparous age-structured models which we are not able to capture in corresponding stage-structured cases. Finally, both age- and stage-structured population models may generate periodic dynamics of low period (either exact or approximate). The important prerequisite is to assume density-dependent survival probabilities. PMID:22297621

  15. Relationships between river discharge and abundance of age 0 redhorses (Moxostoma spp.) in the Oconee River, Georgia, USA, with implications for robust redhorse

    USGS Publications Warehouse

    Peterson, R.; Jennings, Cecil A.; Peterson, J.T.

    2013-01-01

    Robust redhorse (Moxostoma robustum) and notchlip redhorse (M. collapsum) are two species of redhorses that reside in the lower Oconee River, Georgia. Robust redhorse is listed as a state endangered species in Georgia and North Carolina, and attempts to investigate factors affecting its reproductive success have met with limited success. Therefore, catch of robust redhorse young were combined with catch of notchlip redhorse to increase sample size. These congeners with similar spawning repertoire were assumed to respond similarly to environmental conditions. River discharge during spawning and rearing seasons may affect abundance of both redhorses in the lower Oconee River. An information-theoretic approach was used to evaluate the relative support of models relating abundance of age 0 redhorses to monthly discharge statistics that represented magnitude, timing, duration, variability and frequency of river discharge events for April through June 1995–2006. The best-approximating model indicated a negative relationship between the abundance of redhorses and mean maximum river discharge and the number of high pulses during June as well as a positive relationship with intermediate duration of low flows during April–June. This model is 9.6 times more plausible than the next best-fitting model, which revealed a negative relationship between the abundance of redhorses and mean maximum river discharge during May and the number of high pulses during June as well as a positive relationship between abundance and intermediate duration of low flows during April–June. Management implications from the results indicate low-stable flows for at least a 2-week period during spawning and rearing may increase reproductive success of robust and notchlip redhorses.

  16. Heterogeneity of macrozoobenthic assemblages within a Zostera noltii seagrass bed: diversity, abundance, biomass and structuring factors

    NASA Astrophysics Data System (ADS)

    Blanchet, Hugues; de Montaudouin, Xavier; Lucas, Aurélien; Chardy, Pierre

    2004-09-01

    The macrobenthic fauna community of a 70-km 2Zostera noltii seagrass bed (Arcachon bay, France) was studied by sampling 49 stations systematically. A total of 126 taxa were identified. Cluster Analysis based on χ2 distance showed that in this apparently homogeneous habitat, four distinct macrobenthic communities could be identified. Multiple Discriminant Analysis highlighted the major contribution of the overlying water mass as a forcing variable, and, to a lesser extent, of tidal level and Z. noltii's below-ground parts. Seven stations did not constitute any conspicuous group, and were characterized by a low biomass of leaf (<28 g DW m -2), considered as the lowest value to constitute a Z. noltii community. Less than 24% of the seagrass bed was situated in more oceanic waters and at a quite low tidal level. In this relatively stable environment, the macrofauna community was characterized by a high species richness (mean = 39) and a moderate density and high biomass (12 638 individuals m -2 and 25 g AFDW m -2, respectively). Annelids dominated, particularly the oligochaetes. When physical constraints increased (emersion or brackish water conditions), diversity decreased, abundance and biomass increased. The seagrass bed (55%) was flooded with highly fluctuating waters in term of temperature and salinity, here species richness was low (mean = 27) but abundance and biomass were high (24 384 individuals m -2 and 28 g AFDW m -2, respectively), with a dominance of molluscs. The meadow (7%) was in external waters but at a higher tidal level (2.4 m vs 1.8 m above medium low tide level). This community was characterized by the particularly high density (41 826 individuals m -2) and dominance of oligochaetes (79% of total abundance). Species richness was high (mean = 37) here. A fourth community, extending over 12% of the meadow was dominated by the gastropod Hydrobia ulvae but could not be linked to a specific forcing variable. This study confirmed the almost

  17. Abundant mitochondrial DNA variation and world-wide population structure in humpback whales.

    PubMed

    Baker, C S; Perry, A; Bannister, J L; Weinrich, M T; Abernethy, R B; Calambokidis, J; Lien, J; Lambertsen, R H; Ramírez, J U; Vasquez, O

    1993-09-01

    Hunting during the last 200 years reduced many populations of mysticete whales to near extinction. To evaluate potential genetic bottlenecks in these exploited populations, we examined mitochondrial DNA control region sequences from 90 individual humpback whales (Megaptera novaeangliae) representing six subpopulations in three ocean basins. Comparisons of relative nucleotide and nucleotype diversity reveal an abundance of genetic variation in all but one of the oceanic subpopulations. Phylogenetic reconstruction of nucleotypes and analysis of maternal gene flow show that current genetic variation is not due to postexploitation migration between oceans but is a relic of past population variability. Calibration of the rate of control region evolution across three families of whales suggests that existing humpback whale lineages are of ancient origin. Preservation of preexploitation variation in humpback whales may be attributed to their long life-span and overlapping generations and to an effective, though perhaps not timely, international prohibition against hunting. PMID:8367488

  18. Task-specific stability of abundant systems: Structure of variance and motor equivalence.

    PubMed

    Mattos, D; Schöner, G; Zatsiorsky, V M; Latash, M L

    2015-12-01

    Our main goal was to test a hypothesis that transient changes in performance of a steady-state task would result in motor equivalence. We also estimated effects of visual feedback on the amount of reorganization of motor elements. Healthy subjects performed two variations of a four-finger pressing task requiring accurate production of total pressing force (F TOT) and total moment of force (M TOT). In the Jumping-Target task, a sequence of target jumps required transient changes in either F TOT or M TOT. In the Step-Perturbation task, the index finger was lifted by 1cm for 0.5s leading to a change in both F TOT and M TOT. Visual feedback could have been frozen for one of these two variables in both tasks. Deviations in the space of finger modes (hypothetical commands to individual fingers) were quantified in directions of unchanged F TOT and M TOT (motor equivalent - ME) and in directions that changed F TOT and M TOT (non-motor equivalence - nME). Both the ME and nME components increased when the performance changed. After transient target jumps leading to the same combination of F TOT and M TOT, the changes in finger modes had a large residual ME component with only a very small nME component. Without visual feedback, an increase in the nME component was observed without consistent changes in the ME component. Results from the Step-Perturbation task were qualitatively similar. These findings suggest that both external perturbations and purposeful changes in performance trigger a reorganization of elements of an abundant system, leading to large ME change. These results are consistent with the principle of motor abundance corroborating the idea that a family of solutions is facilitated to stabilize values of important performance variables. PMID:26434623

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

    PubMed

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

    2015-01-01

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

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed

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

    2015-01-01

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

  2. Gene-drive in age-structured insect populations.

    PubMed

    Huang, Yunxin; Lloyd, Alun L; Legros, Mathieu; Gould, Fred

    2009-05-01

    To date, models of gene-drive mechanisms proposed for replacing wild-type mosquitoes with transgenic strains that cannot transmit diseases have assumed no age or mating structure. We developed a more detailed model to analyze the effects of age and mating-related factors on the number of engineered insects that must be introduced into a wild population to achieve successful gene-drive based on the Medea and engineered underdominance mechanisms. We found that models without age-structure and mating details can substantially overestimate or underestimate the numbers of engineered insects that must be introduced. In general, introduction thresholds are lowest when young adults are introduced. When both males and females are introduced, assortative mating by age has little impact on the introduction threshold unless the introduced females have diminished reproductive ability because of their age. However, when only males are introduced, assortative mating by age is generally predicted to increase introduction thresholds. In most cases, introduction thresholds are much higher for male-only introductions than for both-sex introductions, but when mating is nearly random and the introduced insects are adults with Medea constructs, male-only introductions can have somewhat lower thresholds than both-sex introductions. Results from this model suggest specific parameters that should be measured in field experiments.

  3. Age-related changes in human vitreous structure.

    PubMed

    Sebag, J

    1987-01-01

    Changes in vitreous structure that occur with aging are important in the pathogenesis of vitreous liquefaction (synchisis senilis), vitreous detachment, and retinal disease. Vitreous morphology was studied in 59 human eyes post-mortem using dark-field horizontal slit illumination of the entire dissected vitreous. In many individuals younger than 30 years, the vitreous was homogeneous in structure. Middle-aged individuals had macroscopic fibers in the central vitreous, which coursed anteroposteriorly and inserted into the vitreous base and the vitreous cortex, posteriorly. During senescence, the vitreous volume was reduced, the vitreous body was collapsed (syneresis), and the fibers were thickened, tortuous, and surrounded by liquid vitreous. This sequence of age-related changes probably results from a progressive reorganization of the hyaluronic acid and collagen molecular networks. Characterization of the molecular events underlying these changes will elucidate the mechanisms of the phenomena of synchisis, syneresis, and detachment, and may provide methods with which to prevent or induce vitreous detachment prophylactically.

  4. Vertical changes in abundance, biomass and community structure of copepods down to 3000 m in the southern Bering Sea

    NASA Astrophysics Data System (ADS)

    Homma, Tomoe; Yamaguchi, Atsushi

    2010-08-01

    Vertical changes in abundance, biomass and community structure of copepods down to 3000 m depth were studied at a single station of the Aleutian Basin of the Bering Sea (53°28'N, 177°00'W, depth 3779 m) on the 14th June 2006. Both abundance and biomass of copepods were greatest near the surface layer and decreased with increase in depth. Abundance and biomass of copepods integrated over 0-3000 m were 1,390,000 inds. m -2 and 5056 mg C m -2, respectively. Copepod carcasses occurred throughout the layer, and the carcass:living specimen ratio was the greatest in the oxygen minimum layer (750-100 m, the ratio was 2.3). A total of 72 calanoid copepod species belonging to 34 genera and 15 families occurred in the 0-3000 m water column (Cyclopoida, Harpacticoida and Poecilostomatoida were not identified to species level). Cluster analysis separated calanoid copepod communities into 5 groups (A-E). Each group was separated by depth, and the depth range of each group was at 0-75 m (A), 75-500 m (B), 500-750 m (C), 750-1500 m (D) and 1500-3000 m (E). Copepods were divided into four types based on the feeding pattern: suspension feeders, suspension feeders in diapause, detritivores and carnivores. In terms of abundance the most dominant group was suspension feeders (mainly Cyclopoida) in the epipelagic zone, and detritivores (mainly Poecilostomatoida) were dominant in the meso- and bathypelagic zones. In terms of biomass, suspension feeders in diapause (calanoid copepods Neocalanus spp. and Eucalanus bungii) were the major component (ca. 10-45%), especially in the 250-3000 m depth. These results are compared with the previous studies in the same region and that down to greater depths in the worldwide oceans.

  5. Artemia parthenogenetica (Branchiopoda: Anostraca) from the Large Aral Sea: Abundance, distribution, population structure and cyst production

    NASA Astrophysics Data System (ADS)

    Arashkevich, Elena G.; Sapozhnikov, P. V.; Soloviov, K. A.; Kudyshkin, T. V.; Zavialov, P. O.

    2009-03-01

    The brine shrimp Artemia parthenogenetica appeared in the Large Aral Sea (Central Asia) in 1998 when mineralization reached 63 ppt. Data on Artemia abundance and biomass, along with temperature and salinity measurements were collected in the western basin during 2002-2006, primarily in the autumn. During the study period, population density grew progressively, both in terms of number, from 250 to 1260 individuals per m 3, and in terms of biomass, from 0.3 to 1.3 g per m 3. In 2005, the population density and spatial distribution in the different parts of the sea (western and eastern basins and strait) was assessed. The horizontal distribution of the Artemia population was uniform in the deep central part of the western basin, although the distribution was quite patchy in the shallow coastal zone. Depth habitat of Artemia was restricted to the upper 20-25 m of depth, as the oxygen depletion and formation of anoxic layer prevented distribution of Artemia to the deeper waters. In autumn, all females reproduced oviparously, with an average clutch size of 30-35 eggs per female. The number of eggs in a clutch was positively correlated with female body length ( r2 = 0.36-0.44).

  6. Coronal Thermal Structure and Abundance of Super-Metal-Rich Late-Type Stars

    NASA Technical Reports Server (NTRS)

    Brickhouse, N.; Mushotzky, Richard F. (Technical Monitor)

    2001-01-01

    This observation is for grating spectroscopy of 30 Ari, a late-type star with very high metallicity. The goal is to use extreme cases to help understand how abundances change from the photosphere to the corona. The only progress is to report to date is preparation for the analysis of the data. The SAO team has produced spectral model predictions for comparison with the observed spectra. The target was obtained by X-ray Multimirror Mission (XMM)-Newton on 2001 January 16 for 28000 sec. Pipeline processing is difficult and the data have not yet been available. Furthermore, we have been cautioned that the data cannot be correctly processed until at least September of this year, as there are problems with the RGS software to extract the spectrum. We have attended two workshops this summer in which results from XMM on late-type stellar coronae were presented including SMM results from GT team members. We noted that only members of the instrument teams are in a position to analyze XMM data.

  7. Models of earth structure inferred from neodymium and strontium isotopic abundances

    PubMed Central

    Wasserburg, G. J.; DePaolo, D. J.

    1979-01-01

    A simplified model of earth structure based on the Nd and Sr isotopic characteristics of oceanic and continental tholeiitic flood basalts is presented, taking into account the motion of crustal plates and a chemical balance for trace elements. The resulting structure that is inferred consists of a lower mantle that is still essentially undifferentiated, overlain by an upper mantle that is the residue of the original source from which the continents were derived. PMID:16592688

  8. Evaluating Functional Diversity: Missing Trait Data and the Importance of Species Abundance Structure and Data Transformation

    PubMed Central

    Bryndová, Michala; Kasari, Liis; Norberg, Anna; Weiss, Matthias; Bishop, Tom R.; Luke, Sarah H.; Sam, Katerina; Le Bagousse-Pinguet, Yoann; Lepš, Jan; Götzenberger, Lars; de Bello, Francesco

    2016-01-01

    Functional diversity (FD) is an important component of biodiversity that quantifies the difference in functional traits between organisms. However, FD studies are often limited by the availability of trait data and FD indices are sensitive to data gaps. The distribution of species abundance and trait data, and its transformation, may further affect the accuracy of indices when data is incomplete. Using an existing approach, we simulated the effects of missing trait data by gradually removing data from a plant, an ant and a bird community dataset (12, 59, and 8 plots containing 62, 297 and 238 species respectively). We ranked plots by FD values calculated from full datasets and then from our increasingly incomplete datasets and compared the ranking between the original and virtually reduced datasets to assess the accuracy of FD indices when used on datasets with increasingly missing data. Finally, we tested the accuracy of FD indices with and without data transformation, and the effect of missing trait data per plot or per the whole pool of species. FD indices became less accurate as the amount of missing data increased, with the loss of accuracy depending on the index. But, where transformation improved the normality of the trait data, FD values from incomplete datasets were more accurate than before transformation. The distribution of data and its transformation are therefore as important as data completeness and can even mitigate the effect of missing data. Since the effect of missing trait values pool-wise or plot-wise depends on the data distribution, the method should be decided case by case. Data distribution and data transformation should be given more careful consideration when designing, analysing and interpreting FD studies, especially where trait data are missing. To this end, we provide the R package “traitor” to facilitate assessments of missing trait data. PMID:26881747

  9. Recurrence and Frequency of Disturbance have Cumulative Effect on Methanotrophic Activity, Abundance, and Community Structure

    PubMed Central

    Ho, Adrian; van den Brink, Erik; Reim, Andreas; Krause, Sascha M. B.; Bodelier, Paul L. E.

    2016-01-01

    Alternate prolonged drought and heavy rainfall is predicted to intensify with global warming. Desiccation-rewetting events alter the soil quality and nutrient concentrations which drive microbial-mediated processes, including methane oxidation, a key biogeochemical process catalyzed by methanotrophic bacteria. Although aerobic methanotrophs showed remarkable resilience to a suite of physical disturbances induced as a single event, their resilience to recurring disturbances is less known. Here, using a rice field soil in a microcosm study, we determined whether recurrence and frequency of desiccation-rewetting impose an accumulating effect on the methanotrophic activity. The response of key aerobic methanotroph subgroups (type Ia, Ib, and II) were monitored using qPCR assays, and was supported by a t-RFLP analysis. The methanotrophic activity was resilient to recurring desiccation-rewetting, but increasing the frequency of the disturbance by twofold significantly decreased methane uptake rate. Both the qPCR and t-RFLP analyses were congruent, showing the dominance of type Ia/Ib methanotrophs prior to disturbance, and after disturbance, the recovering community was predominantly comprised of type Ia (Methylobacter) methanotrophs. Both type Ib and type II (Methylosinus/Methylocystis) methanotrophs were adversely affected by the disturbance, but type II methanotrophs showed recovery over time, indicating relatively higher resilience to the disturbance. This revealed distinct, yet unrecognized traits among the methanotroph community members. Our results show that recurring desiccation-rewetting before a recovery in community abundance had an accumulated effect, compromising methanotrophic activity. While methanotrophs may recover well following sporadic disturbances, their resilience may reach a ‘tipping point’ where activity no longer recovered if disturbance persists and increase in frequency. PMID:26779148

  10. Recurrence and Frequency of Disturbance have Cumulative Effect on Methanotrophic Activity, Abundance, and Community Structure.

    PubMed

    Ho, Adrian; van den Brink, Erik; Reim, Andreas; Krause, Sascha M B; Bodelier, Paul L E

    2015-01-01

    Alternate prolonged drought and heavy rainfall is predicted to intensify with global warming. Desiccation-rewetting events alter the soil quality and nutrient concentrations which drive microbial-mediated processes, including methane oxidation, a key biogeochemical process catalyzed by methanotrophic bacteria. Although aerobic methanotrophs showed remarkable resilience to a suite of physical disturbances induced as a single event, their resilience to recurring disturbances is less known. Here, using a rice field soil in a microcosm study, we determined whether recurrence and frequency of desiccation-rewetting impose an accumulating effect on the methanotrophic activity. The response of key aerobic methanotroph subgroups (type Ia, Ib, and II) were monitored using qPCR assays, and was supported by a t-RFLP analysis. The methanotrophic activity was resilient to recurring desiccation-rewetting, but increasing the frequency of the disturbance by twofold significantly decreased methane uptake rate. Both the qPCR and t-RFLP analyses were congruent, showing the dominance of type Ia/Ib methanotrophs prior to disturbance, and after disturbance, the recovering community was predominantly comprised of type Ia (Methylobacter) methanotrophs. Both type Ib and type II (Methylosinus/Methylocystis) methanotrophs were adversely affected by the disturbance, but type II methanotrophs showed recovery over time, indicating relatively higher resilience to the disturbance. This revealed distinct, yet unrecognized traits among the methanotroph community members. Our results show that recurring desiccation-rewetting before a recovery in community abundance had an accumulated effect, compromising methanotrophic activity. While methanotrophs may recover well following sporadic disturbances, their resilience may reach a 'tipping point' where activity no longer recovered if disturbance persists and increase in frequency.

  11. Evaluating Functional Diversity: Missing Trait Data and the Importance of Species Abundance Structure and Data Transformation.

    PubMed

    Májeková, Maria; Paal, Taavi; Plowman, Nichola S; Bryndová, Michala; Kasari, Liis; Norberg, Anna; Weiss, Matthias; Bishop, Tom R; Luke, Sarah H; Sam, Katerina; Le Bagousse-Pinguet, Yoann; Lepš, Jan; Götzenberger, Lars; de Bello, Francesco

    2016-01-01

    Functional diversity (FD) is an important component of biodiversity that quantifies the difference in functional traits between organisms. However, FD studies are often limited by the availability of trait data and FD indices are sensitive to data gaps. The distribution of species abundance and trait data, and its transformation, may further affect the accuracy of indices when data is incomplete. Using an existing approach, we simulated the effects of missing trait data by gradually removing data from a plant, an ant and a bird community dataset (12, 59, and 8 plots containing 62, 297 and 238 species respectively). We ranked plots by FD values calculated from full datasets and then from our increasingly incomplete datasets and compared the ranking between the original and virtually reduced datasets to assess the accuracy of FD indices when used on datasets with increasingly missing data. Finally, we tested the accuracy of FD indices with and without data transformation, and the effect of missing trait data per plot or per the whole pool of species. FD indices became less accurate as the amount of missing data increased, with the loss of accuracy depending on the index. But, where transformation improved the normality of the trait data, FD values from incomplete datasets were more accurate than before transformation. The distribution of data and its transformation are therefore as important as data completeness and can even mitigate the effect of missing data. Since the effect of missing trait values pool-wise or plot-wise depends on the data distribution, the method should be decided case by case. Data distribution and data transformation should be given more careful consideration when designing, analysing and interpreting FD studies, especially where trait data are missing. To this end, we provide the R package "traitor" to facilitate assessments of missing trait data. PMID:26881747

  12. Evaluating Functional Diversity: Missing Trait Data and the Importance of Species Abundance Structure and Data Transformation.

    PubMed

    Májeková, Maria; Paal, Taavi; Plowman, Nichola S; Bryndová, Michala; Kasari, Liis; Norberg, Anna; Weiss, Matthias; Bishop, Tom R; Luke, Sarah H; Sam, Katerina; Le Bagousse-Pinguet, Yoann; Lepš, Jan; Götzenberger, Lars; de Bello, Francesco

    2016-01-01

    Functional diversity (FD) is an important component of biodiversity that quantifies the difference in functional traits between organisms. However, FD studies are often limited by the availability of trait data and FD indices are sensitive to data gaps. The distribution of species abundance and trait data, and its transformation, may further affect the accuracy of indices when data is incomplete. Using an existing approach, we simulated the effects of missing trait data by gradually removing data from a plant, an ant and a bird community dataset (12, 59, and 8 plots containing 62, 297 and 238 species respectively). We ranked plots by FD values calculated from full datasets and then from our increasingly incomplete datasets and compared the ranking between the original and virtually reduced datasets to assess the accuracy of FD indices when used on datasets with increasingly missing data. Finally, we tested the accuracy of FD indices with and without data transformation, and the effect of missing trait data per plot or per the whole pool of species. FD indices became less accurate as the amount of missing data increased, with the loss of accuracy depending on the index. But, where transformation improved the normality of the trait data, FD values from incomplete datasets were more accurate than before transformation. The distribution of data and its transformation are therefore as important as data completeness and can even mitigate the effect of missing data. Since the effect of missing trait values pool-wise or plot-wise depends on the data distribution, the method should be decided case by case. Data distribution and data transformation should be given more careful consideration when designing, analysing and interpreting FD studies, especially where trait data are missing. To this end, we provide the R package "traitor" to facilitate assessments of missing trait data.

  13. Recurrence and Frequency of Disturbance have Cumulative Effect on Methanotrophic Activity, Abundance, and Community Structure.

    PubMed

    Ho, Adrian; van den Brink, Erik; Reim, Andreas; Krause, Sascha M B; Bodelier, Paul L E

    2015-01-01

    Alternate prolonged drought and heavy rainfall is predicted to intensify with global warming. Desiccation-rewetting events alter the soil quality and nutrient concentrations which drive microbial-mediated processes, including methane oxidation, a key biogeochemical process catalyzed by methanotrophic bacteria. Although aerobic methanotrophs showed remarkable resilience to a suite of physical disturbances induced as a single event, their resilience to recurring disturbances is less known. Here, using a rice field soil in a microcosm study, we determined whether recurrence and frequency of desiccation-rewetting impose an accumulating effect on the methanotrophic activity. The response of key aerobic methanotroph subgroups (type Ia, Ib, and II) were monitored using qPCR assays, and was supported by a t-RFLP analysis. The methanotrophic activity was resilient to recurring desiccation-rewetting, but increasing the frequency of the disturbance by twofold significantly decreased methane uptake rate. Both the qPCR and t-RFLP analyses were congruent, showing the dominance of type Ia/Ib methanotrophs prior to disturbance, and after disturbance, the recovering community was predominantly comprised of type Ia (Methylobacter) methanotrophs. Both type Ib and type II (Methylosinus/Methylocystis) methanotrophs were adversely affected by the disturbance, but type II methanotrophs showed recovery over time, indicating relatively higher resilience to the disturbance. This revealed distinct, yet unrecognized traits among the methanotroph community members. Our results show that recurring desiccation-rewetting before a recovery in community abundance had an accumulated effect, compromising methanotrophic activity. While methanotrophs may recover well following sporadic disturbances, their resilience may reach a 'tipping point' where activity no longer recovered if disturbance persists and increase in frequency. PMID:26779148

  14. Effect of postnatal age and a beta(3)-adrenergic agonist (Zeneca D7114) administration on uncoupling protein-1 abundance in the lamb.

    PubMed

    Bird, J A; Mostyn, A; Clarke, L; Juniper, D T; Budge, H; Stephenson, T; Symonds, M E

    2001-01-01

    We examined the effect of time after birth and beta(3)-adrenergic agonist (Zeneca D7114) administration on uncoupling protein-1 (UCP1) abundance and thermoregulation in the lamb. Forty twin lambs, all born normally at term, were maintained at a cold ambient temperature of between 3 and 8 degrees C. At 0.5, 1.75, 5.25, 11.25 and 23.25 h after birth eight sets of twins were fed 20 ml of formula milk +/- 10 mg kg(-1) of beta(3)-adrenergic agonist, and 45 min after feeding brown adipose tissue (BAT) was sampled. Colonic temperature was measured and BAT analysed for UCP1 abundance, GDP-binding to mitochondrial protein (i.e. thermogenic activity) and catecholamine content. Colonic temperature declined between 1.25 and 6 h from 40.2 degrees C to 39.2 degrees C and then increased to 39.8 degrees C at 12 h, but increased after feeding at all ages. UCP1 abundance increased from 1.25 h after birth, to peak at 2 h after birth in controls, compared with 6 h after birth in beta(3)-adrenergic agonist-treated lambs. The level of GDP-binding to mitochondrial protein did not change significantly with age but was increased by beta(3)-adrenergic agonist treatment. The noradrenaline (norepinephrine) content of BAT increased between 1.25 and 12 h after birth, irrespective of beta(3)-adrenergic agonist administration. The total weight of perirenal BAT plus its lipid, protein and mitochondrial protein content declined over the first 6 h of life. UCP1 development continues over the first 24 h of neonatal life, and can be manipulated by beta(3)-adrenergic agonist administration. This may represent one method of improving thermoregulation in newborn lambs. Experimental Physiology (2001) 86.1, 65-70. PMID:11429621

  15. The Significance of Myriophyllum elatinoides for Swine Wastewater Treatment: Abundance and Community Structure of Ammonia-Oxidizing Microorganisms in Sediments

    PubMed Central

    Li, Xi; Zhang, Miaomiao; Liu, Feng; Li, Yong; He, Yang; Zhang, Shunan; Wu, Jinshui

    2015-01-01

    Myriophyllum elatinoides was reported to effectively treat wastewater by removing nitrogen (N) and phosphorus (P). However, little is known about the abundance and community structure of ammonia-oxidizing microorganisms associated with M. elatinoides purification systems. The objective of this research was to characterize the abundance and community structure of ammonia-oxidizing microorganisms in swine wastewater and determine the main nitrogen removal pathways. In this study, five different waters were treated by M. elatinoides in microcosms for one month. The five waters included tap water (Control), swine wastewater (SW), 50% diluted swine wastewater (50% SW), and two synthetic wastewaters: 200 mg NH4+-N L−1 (200 NH4+-N) and 400 mg NH4+-N L−1 (400 NH4+-N). The most dramatic changes were in NH4+-N and total N (TN) concentrations, with average removal rates of 84% and 90%, respectively, in the treatments containing swine wastewater. On days 7, 14, and 28, the dissolved oxygen (DO) increased by 81.8%, 210.4% and 136.5%, respectively, compared with on day 0, in the swine wastewater. The results also showed that the bacterial amoA (AOB) copy numbers in the sediments of the treatments were significantly higher than those of archaeal amoA (AOA) copy numbers (p = 0.015). In addition, the high DO concentrations in swine wastewater responded well to the high abundance of AOB. The AOA and AOB community distributions were positively related with NO3-N and were negatively related with DO in swine wastewater treatments. In summary, our experimental results suggested that the M. elatinoides purification system could improve the activity of ammonia-oxidizing microorganisms and consequently might contribute to the significant N removal from the swine wastewater. PMID:26444015

  16. Galactic chemical evolution and solar s-process abundances: Dependence on the {sup 13}C-pocket structure

    SciTech Connect

    Bisterzo, S.; Travaglio, C.; Gallino, R.; Wiescher, M.; Käppeler, F. E-mail: sarabisterzo@gmail.com

    2014-05-20

    We study the s-process abundances (A ≳ 90) at the epoch of the solar system formation. Asymptotic giant branch yields are computed with an updated neutron capture network and updated initial solar abundances. We confirm our previous results obtained with a Galactic chemical evolution (GCE) model: (1) as suggested by the s-process spread observed in disk stars and in presolar meteoritic SiC grains, a weighted average of s-process strengths is needed to reproduce the solar s distribution of isotopes with A > 130; and (2) an additional contribution (of about 25%) is required in order to represent the solar s-process abundances of isotopes from A = 90 to 130. Furthermore, we investigate the effect of different internal structures of the {sup 13}C pocket, which may affect the efficiency of the {sup 13}C(α, n){sup 16}O reaction, the major neutron source of the s process. First, keeping the same {sup 13}C profile adopted so far, we modify by a factor of two the mass involved in the pocket; second, we assume a flat {sup 13}C profile in the pocket, and we test again the effects of the variation of the mass of the pocket. We find that GCE s predictions at the epoch of the solar system formation marginally depend on the size and shape of the {sup 13}C pocket once a different weighted range of {sup 13}C-pocket strengths is assumed. We obtain that, independently of the internal structure of the {sup 13}C pocket, the missing solar system s-process contribution in the range from A = 90 to 130 remains essentially the same.

  17. Decreasing Abundance, Increasing Diversity and Changing Structure of the Wild Bee Community (Hymenoptera: Anthophila) along an Urbanization Gradient

    PubMed Central

    Fortel, Laura; Henry, Mickaël; Guilbaud, Laurent; Guirao, Anne Laure; Kuhlmann, Michael; Mouret, Hugues; Rollin, Orianne; Vaissière, Bernard E.

    2014-01-01

    Background Wild bees are important pollinators that have declined in diversity and abundance during the last decades. Habitat destruction and fragmentation associated with urbanization are reported as part of the main causes of this decline. Urbanization involves dramatic changes of the landscape, increasing the proportion of impervious surface while decreasing that of green areas. Few studies have investigated the effects of urbanization on bee communities. We assessed changes in the abundance, species richness, and composition of wild bee community along an urbanization gradient. Methodology/Principal Findings Over two years and on a monthly basis, bees were sampled with colored pan traps and insect nets at 24 sites located along an urbanization gradient. Landscape structure within three different radii was measured at each study site. We captured 291 wild bee species. The abundance of wild bees was negatively correlated with the proportion of impervious surface, while species richness reached a maximum at an intermediate (50%) proportion of impervious surface. The structure of the community changed along the urbanization gradient with more parasitic species in sites with an intermediate proportion of impervious surface. There were also greater numbers of cavity-nesting species and long-tongued species in sites with intermediate or higher proportion of impervious surface. However, urbanization had no effect on the occurrence of species depending on their social behavior or body size. Conclusions/Significance We found nearly a third of the wild bee fauna known from France in our study sites. Indeed, urban areas supported a diverse bee community, but sites with an intermediate level of urbanization were the most speciose ones, including greater proportion of parasitic species. The presence of a diverse array of bee species even in the most urbanized area makes these pollinators worthy of being a flagship group to raise the awareness of urban citizens about

  18. Venus cloud structure and water vapor abundance from Mariner 10 observations

    NASA Technical Reports Server (NTRS)

    Taylor, F. W.

    1976-01-01

    Observations of the Venus atmosphere with the infrared radiometer on Mariner 10 have been analyzed by Taylor (1975) in terms of the vertical distribution of opacity at wavelengths near 11 microns and 45 microns in the thermal infrared. In this paper, we discuss models of the Venus atmosphere which are consistent with the inferred opacity structure. Either a two-layer cloud structure, or a single cloud deck overlaid by a layer containing approximately 40 precipitable microns of water vapor, would have the required limb-darkening characteristics at the wavelengths of observation.

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

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

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

  20. Effects of predation and habitat structure on the abundance and population structure of the rock shrimp Rhynchocinetes typus (Caridea) on temperate rocky reefs.

    PubMed

    Ory, Nicolas C; Dudgeon, D; Dumont, C P; Miranda, L; Thiel, M

    2012-01-01

    Human disturbances, such as overfishing, may disrupt predator-prey interactions and modify food webs. Underwater surveys were carried out at six shallow-water reef barrens in temperate waters of northern-central Chile from October to December 2010 to describe the effects of predation, habitat complexity (low, medium and high) and refuge availability on the abundance and population structure of the rock shrimp Rhynchocinetes typus (Rhynchocinetidae), an important mesoconsumer on subtidal hard substrata. Three sites were within managed (restricted access) areas for fishermen, and three were unmanaged (open-access). Field observations and tethering experiments were conducted to examine the relationship between fish and shrimp abundances, and the relative predation rates on shrimps. Direct effects of predation on R. typus body-size distribution were examined from shrimps collected in the field and fish stomachs. The presence and the abundance of R. typus increased with habitat reef complexity and refuge availability. Shrimp abundance was negatively related to fish abundance in managed areas, but not in open-access areas, where shrimp densities were the highest. Also, predation rates and body-size distribution of shrimps were unrelated, although fish consumed more large shrimps than should be expected from their distribution in the field. R. typus occurred most often in shelters with wide openings, offering limited protection against predators, but providing potential aggregation sites for shrimps. Overall, direct effects of predation on shrimp densities and population structure were weak, but indirect effects on shrimp distribution within reefs appear to have been mediated through behavioural responses. Our study highlights the need to assess both numerical and behavioural responses of prey to determine the effects of predator loss on mesoconsumer populations. PMID:24391278

  1. Effects of predation and habitat structure on the abundance and population structure of the rock shrimp Rhynchocinetes typus (Caridea) on temperate rocky reefs.

    PubMed

    Ory, Nicolas C; Dudgeon, D; Dumont, C P; Miranda, L; Thiel, M

    2012-01-01

    Human disturbances, such as overfishing, may disrupt predator-prey interactions and modify food webs. Underwater surveys were carried out at six shallow-water reef barrens in temperate waters of northern-central Chile from October to December 2010 to describe the effects of predation, habitat complexity (low, medium and high) and refuge availability on the abundance and population structure of the rock shrimp Rhynchocinetes typus (Rhynchocinetidae), an important mesoconsumer on subtidal hard substrata. Three sites were within managed (restricted access) areas for fishermen, and three were unmanaged (open-access). Field observations and tethering experiments were conducted to examine the relationship between fish and shrimp abundances, and the relative predation rates on shrimps. Direct effects of predation on R. typus body-size distribution were examined from shrimps collected in the field and fish stomachs. The presence and the abundance of R. typus increased with habitat reef complexity and refuge availability. Shrimp abundance was negatively related to fish abundance in managed areas, but not in open-access areas, where shrimp densities were the highest. Also, predation rates and body-size distribution of shrimps were unrelated, although fish consumed more large shrimps than should be expected from their distribution in the field. R. typus occurred most often in shelters with wide openings, offering limited protection against predators, but providing potential aggregation sites for shrimps. Overall, direct effects of predation on shrimp densities and population structure were weak, but indirect effects on shrimp distribution within reefs appear to have been mediated through behavioural responses. Our study highlights the need to assess both numerical and behavioural responses of prey to determine the effects of predator loss on mesoconsumer populations.

  2. A spatial age-structured model for describing sea lamprey (Petromyzon marinus) population dynamics

    USGS Publications Warehouse

    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.

  3. Variations in the abundance and structural diversity of microbes forming biofilms in a thermally stressed coral reef system.

    PubMed

    Mahmoud, Huda

    2015-11-30

    Little information is known about biofilm formation in the thermally stressed coral reef systems north of the Arabian Gulf. The current study investigates the abundance and diversity of marine microbes involved in biofilm formation and their succession over a period of 14 weeks (May-August 2007) at temperatures exceeding 32 °C. The results showed variations in microbial numbers and the development of more stable biofilm communities as the biofilms aged. The culture-dependent technique and microscopic examination of the developed biofilms showed the dominance of key species known for their role in precipitating CaCO3 such as Vibrio and in facilitating coral larvae settlement and metamorphosis such as Pseudoalteromonas, Bacillariophyceae and Rhodophyceae. The results revealed biofilm formations with microbial diversities that have the potential to support the larval settlement and metamorphism of marine organisms and to consolidate and stabilize biofilms via the process of calcification in the thermally stressed coral reef system considered herein.

  4. Variations in the abundance and structural diversity of microbes forming biofilms in a thermally stressed coral reef system.

    PubMed

    Mahmoud, Huda

    2015-11-30

    Little information is known about biofilm formation in the thermally stressed coral reef systems north of the Arabian Gulf. The current study investigates the abundance and diversity of marine microbes involved in biofilm formation and their succession over a period of 14 weeks (May-August 2007) at temperatures exceeding 32 °C. The results showed variations in microbial numbers and the development of more stable biofilm communities as the biofilms aged. The culture-dependent technique and microscopic examination of the developed biofilms showed the dominance of key species known for their role in precipitating CaCO3 such as Vibrio and in facilitating coral larvae settlement and metamorphosis such as Pseudoalteromonas, Bacillariophyceae and Rhodophyceae. The results revealed biofilm formations with microbial diversities that have the potential to support the larval settlement and metamorphism of marine organisms and to consolidate and stabilize biofilms via the process of calcification in the thermally stressed coral reef system considered herein. PMID:26494248

  5. Ionization structure and chemical abundances of the Wolf-Rayet nebula NGC 6888 with integral field spectroscopy

    NASA Astrophysics Data System (ADS)

    Fernández-Martín, A.; Vílchez, J. M.; Pérez Montero, E.

    2013-05-01

    n this work we search for the observational footprints of the interactions between the interstellar medium and stellar winds in the Wolf-Rayet nebula NGC 6888 in order to understand its ionization structure, chemical composition, and kinematics. We collected a set of integral field spectroscopy observations across NGC 6888, obtained with PPAK in the optical range performing both 2D and 1D analyses. Attending to the 2D analysis in the north-east part of the nebula, we generated maps of the extinction structure and electron density. We produced diagnostic diagrams and statistical frequency distributions of the radial velocity. Nine integrated spectra were generated over the whole nebula. We measured line intensities to obtain physical parameters and chemical abundances. We inferred that nearly all the zones present an oxygen abundance slightly below the solar values. The derived N/H appears enhanced up to a factor of 6. Helium presents an enrichment in most of the integrated zones, too. Finally, we proposed a scheme of irregular and/or broken shells for NGC 6888 to explain the features observed.

  6. [Age changes of the connective tissue structures of human penis].

    PubMed

    Klimachev, V V; Neĭmark, A I; Gerval'd, V Ia; Bobrov, I P; Avdalian, A M; Muzalevskaia, N I; Gerval'd, I V; Aliev, R T; Cherdantseva, T M

    2011-01-01

    This investigation was aimed at the study of age changes of penis connective tissue structures. Tissue fragments of penis were obtained from 20 cadavers of men at the age of 20-38 years in group I, and from 20 cadavers of men at the age of 41-59 years in group II. The criteria for the exclusion of material from the research were arterial hypertension, diabetes mellitus, atherosclerosis of internal iliac arteries, Peyronie's disease, and anomalies of genital organ development. It was shown that in the cavernous body of penis, aging was associated with the increased amount and thickening of collagen and argyrophilic fibers, decreased content and thinning of elastic fibers, and the reduced amount of smooth muscle cells (SMC). The average area of fibroblast and SMC nucleolus was not different in both groups studied. The average area of endotheliocyte nucleolus was equal to 1.9+/-0.9 microm2 in group II, being lower than that one in group I, in which this index was equal to 2.1+/-0.9 microm2. No differences in the content of type III and IV collagen were found between the study groups. Age-associated decrease in the average area of endothelial cell nucleolus in the cavernous bodies may reflect the reduction of the activity of these cells and may indicate the development of endothelial dysfunction, which is one of the most important steps in the morphogenesis of age-related male erectile dysfunction.

  7. Early-age monitoring of cement structures using FBG sensors

    NASA Astrophysics Data System (ADS)

    Wang, Chuan; Zhou, Zhi; Zhang, Zhichun; Ou, Jinping

    2006-03-01

    With more and more broad applications of the cement-based structures such as neat cement paste, cement mortar and concrete in civil engineering, people hope to find out what their performances should like. The in-service performances of cement-based structures are highly affected by their hardening process during the early-age. But it is still a big problem for traditional sensors to be used to monitor the early curing of cement-based structures due to such disadvantages as difficulties to install sensors inside the concrete, limited measuring points, poor durability and interference of electromagnetic wave and so on. In this paper, according to the sensing properties of the Fiber Bragg Grating sensors and self-characters of the cement-based structures, we have successfully finished measuring and monitoring the early-age inner-strain and temperature changes of the neat cement paste, concrete with and without restrictions, mass concrete structures and negative concrete, respectively. Three types of FBG-based sensors have been developed to monitor the cement-based structures. Besides, the installation techniques and the embedding requirements of FBG sensors in cement-based structures are also discussed. Moreover, such kind of technique has been used in practical structure, 3rd Nanjing Yangtze Bridge, and the results show that FBG sensors are well proper for measuring and monitoring the temperature and strain changes including self-shrinkage, dry shrinkage, plastic shrinkage, temperature expansion, frost heaving and so on inside different cement-based structures. This technique provides us a new useful measuring method on early curing monitoring of cement-based structures and greater understanding of details of their hardening process.

  8. Fish assemblage in a semi-arid Neotropical reservoir: composition, structure and patterns of diversity and abundance.

    PubMed

    Novaes, J L C; Moreira, S I L; Freire, C E C; Sousa, M M O; Costa, R S

    2014-05-01

    The aim of this study was to analyse the composition, structure and spatial and temporal patterns of diversity and abundance of the ichthyofauna of the Santa Cruz Reservoir in semi-arid Brazil. Data were collected quarterly at eight sampling locations on the reservoir between February 2010 and November 2011 using gillnets from 12- to 70-mm mesh that were left in the water for 12h00min during the night. We evaluated the composition, structure and assemblage descriptors (Shannon-Wiener diversity index and equitability, respectively) and catch per unit effort by the number (CPUEn) and biomass (CPUEb) of the ichthyofauna. The 6,047 individuals (399,211.6 g) captured represented three orders, ten families and 20 species, of which four belonged to introduced species. The family Characidae was the most abundant with a total of 2,772 (45.8%) individuals captured. The species-abundance curve fit the log-normal model. In the spatial analysis of diversity, there were significant differences between sampling sites in the lacustrine and fluvial regions, and the highest values were found in the lacustrine region. In the temporal analysis of diversity, significant differences were also observed between the rainy and dry seasons, and the higher values were found during the dry season. Equitability followed the same spatiotemporal pattern as diversity. The Spearman correlation was significantly negative between diversity and rainfall. A cluster analysis spatially separated the ichthyofauna into two groups: one group formed by sampling sites in the fluvial region and another group formed by the remainder of the points in the lacustrine region. Both the CPUEn and CPUEb values were higher at point 8 (fluvial region) and during the rainy season. A two-way ANOVA showed that the CPUEn and CPUEb values were spatially and temporally significant. We conclude that the spatial and temporal trends of diversity in the Santa Cruz reservoir differ from those of other Brazilian reservoirs but that

  9. Minority group status and healthful aging: social structure still matters.

    PubMed

    Angel, Jacqueline L; Angel, Ronald J

    2006-07-01

    During the last 4 decades, a rapid increase has occurred in the number of survey-based and epidemiological studies of the health profiles of adults in general and of the causes of disparities between majority and minority Americans in particular. According to these studies, healthful aging consists of the absence of disease, or at least of the most serious preventable diseases and their consequences, and findings consistently reveal serious African American and Hispanic disadvantages in terms of healthful aging. We (1) briefly review conceptual and operational definitions of race and Hispanic ethnicity, (2) summarize how ethnicity-based differentials in health are related to social structures, and (3) emphasize the importance of attention to the economic, political, and institutional factors that perpetuate poverty and undermine healthful aging among certain groups.

  10. Determinations of rare earth element abundance and U-Pb age of zircons using multispot laser ablation-inductively coupled plasma mass spectrometry.

    PubMed

    Yokoyama, Takaomi D; Suzuki, Toshihiro; Kon, Yoshiaki; Hirata, Takafumi

    2011-12-01

    We have developed a new calibration technique for multielement determination and U-Pb dating of zircon samples using laser ablation-inductively coupled plasma mass spectrometry (ICPMS) coupled with galvanometric optics. With the galvanometric optics, laser ablation of two or more sample materials could be achieved in very short time intervals (~10 ms). The resulting sample aerosols released from different ablation pits or different solid samples were mixed and homogenized within the sample cell and then transported into the ICP ion source. Multiple spot laser ablation enables spiking of analytes or internal standard elements directly into the solid samples, and therefore the standard addition calibration method can be applied for the determination of trace elements in solid samples. In this study, we have measured the rare earth element (REE) abundances of two zircon samples (Nancy 91500 and Prešovice) based on the standard addition technique, using a direct spiking of analytes through a multispot laser ablation of the glass standard material (NIST SRM612). The resulting REE abundance data show good agreement with previously reported values within analytical uncertainties achieved in this study (10% for most elements). Our experiments demonstrated that nonspectroscopic interferences on 14 REEs could be significantly reduced by the standard addition technique employed here. Another advantage of galvanometric devices is the accumulation of sample aerosol released from multiple spots. In this study we have measured the U-Pb age of a zircon sample (LMR) using an accumulation of sample aerosols released from 10 separate ablation pits of low diameters (~8 μm). The resulting (238)U-(206)Pb age data for the LMR zircons was 369 ± 64 Ma, which is in good agreement with previously reported age data (367.6 ± 1.5 Ma). (1) The data obtained here clearly demonstrate that the multiple spot laser ablation-ICPMS technique can become a powerful approach for elemental and isotopic

  11. Ageing management of french NPP civil work structures

    NASA Astrophysics Data System (ADS)

    Gallitre, E.; Dauffer, D.

    2011-04-01

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

  12. Spatial Genetic Structure of the Abundant and Widespread Peatmoss Sphagnum magellanicum Brid.

    PubMed Central

    Kyrkjeeide, Magni Olsen; Hassel, Kristian; Flatberg, Kjell Ivar; Shaw, A. Jonathan; Yousefi, Narjes; Stenøien, Hans K.

    2016-01-01

    Spore-producing organisms have small dispersal units enabling them to become widespread across continents. However, barriers to gene flow and cryptic speciation may exist. The common, haploid peatmoss Sphagnum magellanicum occurs in both the Northern and Southern hemisphere, and is commonly used as a model in studies of peatland ecology and peatmoss physiology. Even though it will likely act as a rich source in functional genomics studies in years to come, surprisingly little is known about levels of genetic variability and structuring in this species. Here, we assess for the first time how genetic variation in S. magellanicum is spatially structured across its full distribution range (Northern Hemisphere and South America). The morphologically similar species S. alaskense was included for comparison. In total, 195 plants were genotyped at 15 microsatellite loci. Sequences from two plastid loci (trnG and trnL) were obtained from 30 samples. Our results show that S. alaskense and almost all plants of S. magellanicum in the northern Pacific area are diploids and share the same gene pool. Haploid plants occur in South America, Europe, eastern North America, western North America, and southern Asia, and five genetically differentiated groups with different distribution ranges were found. Our results indicate that S. magellanicum consists of several distinct genetic groups, seemingly with little or no gene flow among them. Noteworthy, the geographical separation of diploids and haploids is strikingly similar to patterns found within other haploid Sphagnum species spanning the Northern Hemisphere. Our results confirm a genetic division between the Beringian and the Atlantic that seems to be a general pattern in Sphagnum taxa. The pattern of strong genetic population structuring throughout the distribution range of morphologically similar plants need to be considered in future functional genomic studies of S. magellanicum. PMID:26859563

  13. The role of harvesting in age-structured populations: disentangling dynamic and age truncation effects.

    PubMed

    Wikström, Anders; Ripa, Jörgen; Jonzén, Niclas

    2012-12-01

    Understanding the processes generating fluctuations of natural populations lies at the very heart of academic ecology. It is also very important for applications such as fisheries management and pest control. We are interested in the effect of harvesting on population fluctuations and for that purpose we develop and analyze an age-structured model where recruitment is a stochastic process and the adult segment of the population is harvested. When a constant annual harvest is taken the coefficient of variation of the adult population increases for most parameter values due to the age truncation effect, i.e. an increased variability in a juvenescent population due to the removal of older individuals. However, if a constant proportion of the adults is harvested the age truncation effect is sometimes counteracted by a stabilizing dynamic effect of harvesting. Depending on parameter values mirroring different life histories, proportional harvest can either increase or decrease the relative fluctuations of an exploited population. When there is a demographic Allee effect the ratio of juveniles to adults may actually decrease with harvesting. We conclude that, depending on life history and harvest strategy, harvesting can either reinforce or dampen population fluctuations due to the relative importance of stabilizing dynamic effects and the age truncation effect. The strength of the latter is highly dependent on the fished population's endogenous, age-structured dynamics. More specifically, we predict that populations with strong and positively autocorrelated dynamics will show stronger age truncation effect, a testable prediction that offers a simple rule-of-thumb assessment of a population's vulnerability to exploitation.

  14. Effects of different fertilizers on the abundance and community structure of ammonia oxidizers in a yellow clay soil.

    PubMed

    Yao, Huaiying; Huang, Sha; Qiu, Qiongfen; Li, Yaying; Wu, Lianghuan; Mi, Wenhai; Dai, Feng

    2016-08-01

    Yellow clay paddy soil (Oxisols) is a typical soil with low productivity in southern China. Nitrification inhibitors and slow release fertilizers have been used to improve nitrogen fertilizer utilization and reduce environmental impaction of the paddy soil. However, their effects on ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in paddy soil have rarely been investigated. In the present work, we compared the influences of several slow release fertilizers and nitrification inhibitors on the community structure and activities of the ammonia oxidizers in yellow clay soil. The abundances and community compositions of AOA and AOB were determined with qPCR, terminal restriction fragment length polymorphism (T-RFLP), and clone library approaches. Our results indicated that the potential nitrification rate (PNR) of the soil was significantly related to the abundances of both AOA and AOB. Nitrogen fertilizer application stimulated the growth of AOA and AOB, and the combinations of nitrapyrin with urea (NPU) and urea-formaldehyde (UF) inhibited the growth of AOA and AOB, respectively. Compared with other treatments, the applications of NPU and UF also led to significant shifts in the community compositions of AOA and AOB, respectively. NPU showed an inhibitory effect on AOA T-RF 166 bp that belonged to Nitrosotalea. UF had a negative effect on AOB T-RF 62 bp that was assigned to Nitrosospira. These results suggested that NPU inhibited PNR and increased nitrogen use efficiency (NUE) by inhibiting the growth of AOA and altering AOA community. UF showed no effect on NUE but decreased AOB abundance and shifted AOB community.

  15. Computer Simulation of Sexual Selection on Age-Structured Populations

    NASA Astrophysics Data System (ADS)

    Martins, S. G. F.; Penna, T. J. P.

    Using computer simulations of a bit-string model for age-structured populations, we found that sexual selection of older males is advantageous, from an evolutionary point of view. These results are in opposition to a recent proposal of females choosing younger males. Our simulations are based on findings from recent studies of polygynous bird species. Since secondary sex characters are found mostly in males, we could make use of asexual populations that can be implemented in a fast and efficient way.

  16. Microgeographic population structure of green swordail fish: genetic differentiation despite abundant migration.

    PubMed

    Tatarenkov, A; Healey, C I M; Avise, J C

    2010-01-01

    Swordtails (Xiphophorus; Poeciliidae) have figured prominently in research on fish mating behaviours, sexual selection, and carcinogenesis, but their population structures and dispersal patterns have been relatively neglected. Using nine microsatellite loci, we estimated genetic differentiation in Xiphophorus helleri within and between adjacent streams in Belize. The genetic data were complemented by a tagging study of movement within one stream. In the absence of physical dispersal barriers (waterfalls), population structure followed an isolation by distance (IBD) pattern. Genetic differentiation (F(ST) up to 0.07) was significant between and within creeks, despite high dispersal in the latter as judged by the tagging data. Such heterogeneity apparently was a result of genetic drift in local demes, due to small population sizes and highly skewed paternity. The IBD pattern was interrupted by waterfalls, boosting F(ST) above 0.30 between adjacent samples across these barriers. Overall, our results are helpful in understanding the interplay of evolutionary forces and population dynamics in a small fish living in a changeable habitat. PMID:20015140

  17. Microgeographic population structure of green swordail fish: genetic differentiation despite abundant migration.

    PubMed

    Tatarenkov, A; Healey, C I M; Avise, J C

    2010-01-01

    Swordtails (Xiphophorus; Poeciliidae) have figured prominently in research on fish mating behaviours, sexual selection, and carcinogenesis, but their population structures and dispersal patterns have been relatively neglected. Using nine microsatellite loci, we estimated genetic differentiation in Xiphophorus helleri within and between adjacent streams in Belize. The genetic data were complemented by a tagging study of movement within one stream. In the absence of physical dispersal barriers (waterfalls), population structure followed an isolation by distance (IBD) pattern. Genetic differentiation (F(ST) up to 0.07) was significant between and within creeks, despite high dispersal in the latter as judged by the tagging data. Such heterogeneity apparently was a result of genetic drift in local demes, due to small population sizes and highly skewed paternity. The IBD pattern was interrupted by waterfalls, boosting F(ST) above 0.30 between adjacent samples across these barriers. Overall, our results are helpful in understanding the interplay of evolutionary forces and population dynamics in a small fish living in a changeable habitat.

  18. The Effects of Colony Structure and Resource Abundance on Food Dispersal in Tapinoma sessile (Hymenoptera: Formicidae)

    PubMed Central

    VanWeelden, M. T.; Bennett, G.; Buczkowski, G.

    2015-01-01

    The odorous house ant, Tapinoma sessile (Say) (Hymenoptera: Formicidae), exhibits a high degree of variation in colony spatial structure which may have direct and indirect effects on foraging. Protein marking and mark–release–recapture techniques were utilized to examine the effect of colony spatial structure on food dispersal. Sucrose water spiked with rabbit IgG protein was presented to colonies with varying spatial configurations in laboratory and field experiments. In monodomous lab colonies, the rate and extent of food dispersal was rapid due to a decrease in foraging area. In polydomous colonies, food dispersal was slower because conspecifics were forced to forage and share food over longer distances. However, over time, food was present in all extremities of the colony. Experiments conducted in the field produced similar results, with nests in close proximity to food yielding higher percentages of workers scoring positive for the marker. However, the percentage of workers possessing the marker decreased over time. Results from this study provide experimental data on mechanisms of food dispersal in monodomous and polydomous colonies of ants, and may be important for increasing the efficacy of management strategies against T. sessile and other pest ant species. PMID:25688088

  19. The effects of colony structure and resource abundance on food dispersal in Tapinoma sessile (Hymenoptera: Formicidae).

    PubMed

    VanWeelden, M T; Bennett, G; Buczkowski, G

    2015-01-01

    The odorous house ant, Tapinoma sessile (Say) (Hymenoptera: Formicidae), exhibits a high degree of variation in colony spatial structure which may have direct and indirect effects on foraging. Protein marking and mark-release-recapture techniques were utilized to examine the effect of colony spatial structure on food dispersal. Sucrose water spiked with rabbit IgG protein was presented to colonies with varying spatial configurations in laboratory and field experiments. In monodomous lab colonies, the rate and extent of food dispersal was rapid due to a decrease in foraging area. In polydomous colonies, food dispersal was slower because conspecifics were forced to forage and share food over longer distances. However, over time, food was present in all extremities of the colony. Experiments conducted in the field produced similar results, with nests in close proximity to food yielding higher percentages of workers scoring positive for the marker. However, the percentage of workers possessing the marker decreased over time. Results from this study provide experimental data on mechanisms of food dispersal in monodomous and polydomous colonies of ants, and may be important for increasing the efficacy of management strategies against T. sessile and other pest ant species. PMID:25688088

  20. Profiling of the Molecular Weight and Structural Isomer Abundance of Macroalgae-Derived Phlorotannins

    PubMed Central

    Heffernan, Natalie; Brunton, Nigel P.; FitzGerald, Richard J.; Smyth, Thomas J.

    2015-01-01

    Phlorotannins are a group of complex polymers of phloroglucinol (1,3,5-trihydroxybenzene) unique to macroalgae. These phenolic compounds are integral structural components of the cell wall in brown algae, but also play many secondary ecological roles such as protection from UV radiation and defense against grazing. This study employed Ultra Performance Liquid Chromatography (UPLC) with tandem mass spectrometry to investigate isomeric complexity and observed differences in phlorotannins derived from macroalgae harvested off the Irish coast (Fucus serratus, Fucus vesiculosus, Himanthalia elongata and Cystoseira nodicaulis). Antioxidant activity and total phenolic content assays were used as an index for producing phlorotannin fractions, enriched using molecular weight cut-off dialysis with subsequent flash chromatography to profile phlorotannin isomers in these macroalgae. These fractions were profiled using UPLC-MS with multiple reaction monitoring (MRM) and the level of isomerization for specific molecular weight phlorotannins between 3 and 16 monomers were determined. The majority of the low molecular weight (LMW) phlorotannins were found to have a molecular weight range equivalent to 4–12 monomers of phloroglucinol. The level of isomerization within the individual macroalgal species differed, resulting in substantially different numbers of phlorotannin isomers for particular molecular weights. F. vesiculosus had the highest number of isomers of 61 at one specific molecular mass, corresponding to 12 phloroglucinol units (PGUs). These results highlight the complex nature of these extracts and emphasize the challenges involved in structural elucidation of these compounds. PMID:25603345

  1. Profiling of the molecular weight and structural isomer abundance of macroalgae-derived phlorotannins.

    PubMed

    Heffernan, Natalie; Brunton, Nigel P; FitzGerald, Richard J; Smyth, Thomas J

    2015-01-16

    Phlorotannins are a group of complex polymers of phloroglucinol (1,3,5-trihydroxybenzene) unique to macroalgae. These phenolic compounds are integral structural components of the cell wall in brown algae, but also play many secondary ecological roles such as protection from UV radiation and defense against grazing. This study employed Ultra Performance Liquid Chromatography (UPLC) with tandem mass spectrometry to investigate isomeric complexity and observed differences in phlorotannins derived from macroalgae harvested off the Irish coast (Fucus serratus, Fucus vesiculosus, Himanthalia elongata and Cystoseira nodicaulis). Antioxidant activity and total phenolic content assays were used as an index for producing phlorotannin fractions, enriched using molecular weight cut-off dialysis with subsequent flash chromatography to profile phlorotannin isomers in these macroalgae. These fractions were profiled using UPLC-MS with multiple reaction monitoring (MRM) and the level of isomerization for specific molecular weight phlorotannins between 3 and 16 monomers were determined. The majority of the low molecular weight (LMW) phlorotannins were found to have a molecular weight range equivalent to 4-12 monomers of phloroglucinol. The level of isomerization within the individual macroalgal species differed, resulting in substantially different numbers of phlorotannin isomers for particular molecular weights. F. vesiculosus had the highest number of isomers of 61 at one specific molecular mass, corresponding to 12 phloroglucinol units (PGUs). These results highlight the complex nature of these extracts and emphasize the challenges involved in structural elucidation of these compounds.

  2. [Age structure and growth characteristic of Castanopsis fargesii population].

    PubMed

    Song, Kun; Da, Liang-jun; Yang, Tong-hui; Yang, Xu-feng

    2007-02-01

    In this paper, the age structure and growth characteristics of Castanopsis fargesii population in a shade-tolerant broadleaved evergreen forest were studied, aimed to understand more about the regeneration patterns and dynamics of this population. The results showed that the age structure of C. fargesii population was of sporadic type, with two death peaks of a 30-year gap. This population had a good plasticity in growth to light condition. Because there were no significant differences in light condition under the canopy in vertical, the saplings came into their first suppression period when they were 5-8 years old, with a height growth rate less than 0. 1 m x a(-1) lasting for 10 years. The beginning time of the first growth suppression period was by the end of the first death peak of the population, and the ending time of the first growth suppression period was at the beginning of the second death peak of the population, demonstrating that growth characteristic was the key factor affecting the age structure of C. fargesii.

  3. Age structure and disturbance legacy of North American forests

    NASA Astrophysics Data System (ADS)

    Pan, Y.; Chen, J. M.; Birdsey, R.; McCullough, K.; He, L.; Deng, F.

    2010-02-01

    Most forests of the world are recovering from a past disturbance. It is well known that forest disturbances profoundly affect carbon stock and fluxes in forest ecosystems, yet it has been a great challenge to assess disturbance impacts in estimates of forest carbon budgets. Net sequestration or loss of CO2 by forests after disturbance follows a predictable pattern with forest recovery. Forest age, which is related to time since disturbance, is the most available surrogate variable for various forest carbon analyses that concern the impact of disturbance. In this study, we compiled the first continental forest age map of North America by combining forest inventory data, historical fire data, optical satellite data and the dataset from NASA's LEDAPS project. Mexico and interior Alaska are excluded from this initial map due to unavailability of all required data sets, but work is underway to develop some different methodology for these areas. We discuss the significance of disturbance legacy from the past, as represented by current forest age structure in different regions of the US and Canada, tracking back disturbances caused by human and nature over centuries and at various scales. We also show how such information can be used with inventory data for analyzing carbon management opportunities, and other modeling applications. By combining geographic information about forest age with estimated C dynamics by forest type, it is possible to conduct a simple but powerful analysis of the net CO2 uptake by forests, and the potential for increasing (or decreasing) this rate as a result of direct human intervention in the disturbance/age status. The forest age map may also help address the recent concern that the terrestrial C sink from forest regrowth in North America may saturate in the next few decades. Finally, we describe how the forest age data can be used in large-scale carbon modeling, both for land-based biogeochemistry models and atmosphere-based inversion models

  4. Age structure and disturbance legacy of North American forests

    NASA Astrophysics Data System (ADS)

    Pan, Y.; Chen, J. M.; Birdsey, R.; McCullough, K.; He, L.; Deng, F.

    2011-03-01

    Most forests of the world are recovering from a past disturbance. It is well known that forest disturbances profoundly affect carbon stocks and fluxes in forest ecosystems, yet it has been a great challenge to assess disturbance impacts in estimates of forest carbon budgets. Net sequestration or loss of CO2 by forests after disturbance follows a predictable pattern with forest recovery. Forest age, which is related to time since disturbance, is a useful surrogate variable for analyses of the impact of disturbance on forest carbon. In this study, we compiled the first continental forest age map of North America by combining forest inventory data, historical fire data, optical satellite data and the dataset from NASA's Landsat Ecosystem Disturbance Adaptive Processing System (LEDAPS) project. A companion map of the standard deviations for age estimates was developed for quantifying uncertainty. We discuss the significance of the disturbance legacy from the past, as represented by current forest age structure in different regions of the US and Canada, by analyzing the causes of disturbances from land management and nature over centuries and at various scales. We also show how such information can be used with inventory data for analyzing carbon management opportunities. By combining geographic information about forest age with estimated C dynamics by forest type, it is possible to conduct a simple but powerful analysis of the net CO2 uptake by forests, and the potential for increasing (or decreasing) this rate as a result of direct human intervention in the disturbance/age status. Finally, we describe how the forest age data can be used in large-scale carbon modeling, both for land-based biogeochemistry models and atmosphere-based inversion models, in order to improve the spatial accuracy of carbon cycle simulations.

  5. Volatile Abundances and the Deep Cloud Structure in Jupiter's Great Red Spot

    NASA Astrophysics Data System (ADS)

    Bjoraker, Gordon; de Pater, Imke; Wong, Michael H.; Adamkovics, Mate; Hewagama, Tilak; Hesman, Brigette

    2016-10-01

    Despite the presence of thick upper level clouds, Jupiter's Great Red Spot preserves the signature of physical conditions at much deeper levels in the troposphere. The Great Red Spot is dark at 5 microns due to thick clouds, but imaging alone does not reveal which cloud layers are responsible for attenuating this radiation. We used NIRSPEC on the Keck telescope and CSHELL on the Infrared Telescope Facility to spectrally resolve line profiles of CH3D and other molecules on Jupiter in order to derive the pressure of the line formation region in the 5-micron window. Variations in CH3D line shape with position on Jupiter are due to cloud structure rather than changes in gas mole fraction.By aligning the slit east/west on Jupiter, we sampled the Great Red Spot and a Hot Spot at the same latitude. The profile of the CH3D lines is very broad in the Hot Spot due to collisions with up to 8 bars of H2, where unit optical depth due to collision induced H2 opacity occurs. The extreme width of these CH3D features implies that Hot Spots do not have significant cloud opacity where water is expected to condense. Within the Great Red Spot, the line profiles are substantially narrower than in the Hot Spot. The best fit to the line shape of CH3D requires an opaque cloud at 5 bars, which we identify as being a water cloud. Thermal radiation from the 5-bar level is further attenuated by upper level clouds, but these colder clouds do not change the shape of the spectrum. Once we have established a cloud structure, gas mole fractions may then be retrieved. Gaseous H2O is clearly evident in the Great Red Spot, which provides independent evidence that we are sounding deep in Jupiter's atmosphere. A combination of Keck and IRTF data allows us to retrieve NH3, PH3, and gaseous H2O inside the Hot Spot and within the Great Red Spot. This technique can be applied to study the deep cloud structure anywhere on Jupiter whether or not upper level clouds are present. We will use this technique to

  6. Ionization structure and chemical abundances of the Wolf-Rayet nebula NGC 6888 with integral field spectroscopy

    NASA Astrophysics Data System (ADS)

    Fernández-Martín, A.; Martín-Gordón, D.; Vílchez, J. M.; Pérez Montero, E.; Riera, A.; Sánchez, S. F.

    2012-05-01

    Context. The study of nebulae around Wolf-Rayet (WR) stars gives us clues about the mass-loss history of massive stars, as well as about the chemical enrichment of the interstellar medium (ISM). Aims: This work aims to search for the observational footprints of the interactions between the ISM and stellar winds in the WR nebula NGC 6888 in order to understand its ionization structure, chemical composition, and kinematics. Methods: We have collected a set of integral field spectroscopy observations across NGC 6888, obtained with PPAK in the optical range performing both 2D and 1D analyses. Attending to the 2D analysis in the northeast part of NGC 6888, we have generated maps of the extinction structure and electron density. We produced statistical frequency distributions of the radial velocity and diagnostic diagrams. Furthermore, we performed a thorough study of integrated spectra in nine regions over the whole nebula. Results: The 2D study has revealed two main behaviours. We have found that the spectra of a localized region to the southwest of this pointing can be represented well by shock models assuming n = 1000 cm-3, twice solar abundances, and shock velocities from 250 to 400 km s-1. With the 1D analysis we derived electron densities ranging from <100 to 360 cm-3. The electron temperature varies from ~7700 K to ~10 200 K. A strong variation of up to a factor 10 between different regions in the nitrogen abundance has been found: N/H appears lower than the solar abundance in those positions observed at the edges and very enhanced in the observed inner parts. Oxygen appears slightly underabundant with respect to solar value, whereas the helium abundance is found to be above it. We propose a scenario for the evolution of NGC 6888 to explain the features observed. This scheme consists of a structure of multiple shells: i) an inner and broken shell with material from the interaction between the supergiant and WR shells, presenting an overabundance in N/H and a

  7. Variations in the abundance of fisheries resources and ecosystem structure in the Japan/East Sea

    NASA Astrophysics Data System (ADS)

    Zhang, Chang Ik; Lee, Jae Bong; Seo, Young Il; Yoon, Sang Cheol; Kim, Suam

    2004-05-01

    Evidence supports the hypothesis that two climatic regime shifts in the North Pacific and the Japan/East Sea, have affected the dynamics of the marine ecosystem and fisheries resources from 1960 to 2000. Changes in both mixed layer depth (MLD) and primary production were detected in the Japan/East Sea after 1976. The 1976 regime shift appears to have caused the biomass replacement with changes in catch production of major exploited fisheries resources, including Pacific saury, Pacific sardine and filefish. Both fisheries yield and fish distribution are reflected in these decadal fluctuations. In the 1960s and 1990s, common squid dominated the catches whereas in the 1970s and 1980s, it was replaced by walleye pollock. In the post-1988 regime shift, the distribution of horse mackerel shifted westward and southward and its distributional overlap with common mackerel decreased. The habitat of Pacific sardine also shifted away from mackerel habitats during this period. To evaluate changes in the organization and structure of the ecosystem in the Japan/East Sea, a mass-balanced model, Ecopath, was employed. Based on two mass-balanced models, representing before (1970-75) and after (1978-84) the 1976 regime shift, the weighted mean trophic level of catch increased from 3.09 before to 3.28 after. Total biomass of species groups in the Japan/East Sea ecosystem increased by 15% and total catch production increased by 48% due to the 1976 regime shift. The largest changes occurred at mid-trophic levels, occupied by fishes and cephalopods. The dominant predatory species shifted from cephalopods to walleye pollock due to the 1976 regime shift. It is concluded that the climatic regime shifts caused changes in the structure of the ecosystem and the roles of major species, as well as, large variations in biomass and production of fisheries resources.

  8. A Comparison of Anammox Bacterial Abundance and Community Structures in Three Different Emerged Plants-Related Sediments.

    PubMed

    Chu, Jinyu; Zhang, Jinping; Zhou, Xiaohong; Liu, Biao; Li, Yimin

    2015-09-01

    Quantitative polymerase chain reaction (qPCR) assays and 16S rRNA gene clone libraries were used to document the abundance, diversity and community structure of anaerobic ammonia-oxidising (anammox) bacteria in the rhizosphere and non-rhizosphere sediments of three emergent macrophyte species (Iris pseudacorus, Thalia dealbata and Typha orientalis). The qPCR results confirmed the existence of anammox bacteria (AMX) with observed log number of gene copies per dry gram sediment ranging from 5.00 to 6.78. AMX was more abundant in T. orientalis-associated sediments than in the other two plant species. The I. pseudacorus- and T. orientalis-associated sediments had higher Shannon diversity values, indicating higher AMX diversity in these sediments. Based on the 16S rRNA gene, Candidatus 'Brocadia', Candidatus 'Kuenenia', Candidatus 'Jettenia' and new clusters were observed with the predominant Candidatus 'Kuenenia' cluster. The I. pseudacorus-associated sediments contained all the sequences of the C. 'Jettenia' cluster. Sequences obtained from T. orientalis-associated sediments contributed more than 90 % sequences in the new cluster, whereas none was found from I. pseudacorus. The new cluster was distantly related to known sequences; thus, this cluster was grouped outside the known clusters, indicating that the new cluster may be a new Planctomycetales genus. Further studies should be undertaken to confirm this finding. PMID:26077223

  9. A Comparison of Anammox Bacterial Abundance and Community Structures in Three Different Emerged Plants-Related Sediments.

    PubMed

    Chu, Jinyu; Zhang, Jinping; Zhou, Xiaohong; Liu, Biao; Li, Yimin

    2015-09-01

    Quantitative polymerase chain reaction (qPCR) assays and 16S rRNA gene clone libraries were used to document the abundance, diversity and community structure of anaerobic ammonia-oxidising (anammox) bacteria in the rhizosphere and non-rhizosphere sediments of three emergent macrophyte species (Iris pseudacorus, Thalia dealbata and Typha orientalis). The qPCR results confirmed the existence of anammox bacteria (AMX) with observed log number of gene copies per dry gram sediment ranging from 5.00 to 6.78. AMX was more abundant in T. orientalis-associated sediments than in the other two plant species. The I. pseudacorus- and T. orientalis-associated sediments had higher Shannon diversity values, indicating higher AMX diversity in these sediments. Based on the 16S rRNA gene, Candidatus 'Brocadia', Candidatus 'Kuenenia', Candidatus 'Jettenia' and new clusters were observed with the predominant Candidatus 'Kuenenia' cluster. The I. pseudacorus-associated sediments contained all the sequences of the C. 'Jettenia' cluster. Sequences obtained from T. orientalis-associated sediments contributed more than 90 % sequences in the new cluster, whereas none was found from I. pseudacorus. The new cluster was distantly related to known sequences; thus, this cluster was grouped outside the known clusters, indicating that the new cluster may be a new Planctomycetales genus. Further studies should be undertaken to confirm this finding.

  10. THE C+N+O ABUNDANCE OF {omega} CENTAURI GIANT STARS: IMPLICATIONS FOR THE CHEMICAL-ENRICHMENT SCENARIO AND THE RELATIVE AGES OF DIFFERENT STELLAR POPULATIONS

    SciTech Connect

    Marino, A. F.; Milone, A. P.; Aparicio, A.; Piotto, G.; Cassisi, S.; D'Antona, F.; Anderson, J.; Bedin, L. R.; Renzini, A.; Villanova, S. E-mail: milone@iac.es E-mail: giampaolo.piotto@unipd.it E-mail: dantona@oa-roma.inaf.it E-mail: luigi.bedin@oapd.inaf.it E-mail: svillanova@astro-udec.cl

    2012-02-10

    We present a chemical-composition analysis of 77 red-giant stars in Omega Centauri. We have measured abundances for carbon and nitrogen, and combined our results with abundances of O, Na, La, and Fe that we determined in our previous work. Our aim is to better understand the peculiar chemical-enrichment history of this cluster by studying how the total C+N+O content varies among the different metallicity stellar groups, and among stars at different places along the Na-O anticorrelation. We find that the (anti)correlations among the light elements that would be expected on theoretical grounds for matter that has been nuclearly processed via high-temperature proton captures. The overall [(C+N+O)/Fe] increases by {approx}0.5 dex from [Fe/H] {approx}-2.0 to [Fe/H] {approx}-0.9. Our results provide insight into the chemical-enrichment history of the cluster, and the measured CNO variations provide important corrections for estimating the relative ages of the different stellar populations.

  11. Effects of Habitat Structure and Fragmentation on Diversity and Abundance of Primates in Tropical Deciduous Forests in Bolivia

    PubMed Central

    Büntge, Anna B. S.; Herzog, Sebastian K.; Kessler, Michael

    2010-01-01

    Habitat structure and anthropogenic disturbance are known to affect primate diversity and abundance. However, researchers have focused on lowland rain forests, whereas endangered deciduous forests have been neglected. We aimed to investigate the relationships between primate diversity and abundance and habitat parameters in 10 deciduous forest fragments southeast of Santa Cruz, Bolivia. We obtained primate data via line-transect surveys and visual and acoustic observations. In addition, we assessed the vegetation structure (canopy height, understory density), size, isolation time, and surrounding forest area of the fragments. We interpreted our results in the context of the historical distribution data for primates in the area before fragmentation and interviews with local people. We detected 5 of the 8 historically observed primate species: Alouatta caraya, Aotus azarae boliviensis, Callithrix melanura, Callicebus donacophilus, and Cebus libidinosus juruanus. Total species number and detection rates decreased with understory density. Detection rates also negatively correlated with forest areas in the surroundings of a fragment, which may be due to variables not assessed, i.e., fragment shape, distance to nearest town. Observations for Alouatta and Aotus were too few to conduct further statistics. Cebus and Callicebus were present in 90% and 70% of the sites, respectively, and their density did not correlate with any of the habitat variables assessed, signaling high ecological plasticity and adaptability to anthropogenic impact in these species. Detections of Callithrix were higher in areas with low forest strata. Our study provides baseline data for future fragmentation studies in Neotropical dry deciduous forests and sets a base for specific conservation measures. PMID:20949116

  12. Effects of Habitat Structure and Fragmentation on Diversity and Abundance of Primates in Tropical Deciduous Forests in Bolivia.

    PubMed

    Pyritz, Lennart W; Büntge, Anna B S; Herzog, Sebastian K; Kessler, Michael

    2010-10-01

    Habitat structure and anthropogenic disturbance are known to affect primate diversity and abundance. However, researchers have focused on lowland rain forests, whereas endangered deciduous forests have been neglected. We aimed to investigate the relationships between primate diversity and abundance and habitat parameters in 10 deciduous forest fragments southeast of Santa Cruz, Bolivia. We obtained primate data via line-transect surveys and visual and acoustic observations. In addition, we assessed the vegetation structure (canopy height, understory density), size, isolation time, and surrounding forest area of the fragments. We interpreted our results in the context of the historical distribution data for primates in the area before fragmentation and interviews with local people. We detected 5 of the 8 historically observed primate species: Alouatta caraya, Aotus azarae boliviensis, Callithrix melanura, Callicebus donacophilus, and Cebus libidinosus juruanus. Total species number and detection rates decreased with understory density. Detection rates also negatively correlated with forest areas in the surroundings of a fragment, which may be due to variables not assessed, i.e., fragment shape, distance to nearest town. Observations for Alouatta and Aotus were too few to conduct further statistics. Cebus and Callicebus were present in 90% and 70% of the sites, respectively, and their density did not correlate with any of the habitat variables assessed, signaling high ecological plasticity and adaptability to anthropogenic impact in these species. Detections of Callithrix were higher in areas with low forest strata. Our study provides baseline data for future fragmentation studies in Neotropical dry deciduous forests and sets a base for specific conservation measures.

  13. Abundance of non-native crabs in intertidal habitats of New England with natural and artificial structure.

    PubMed

    Lovely, Christina M; O'Connor, Nancy J; Judge, Michael L

    2015-01-01

    Marine habitats containing complex physical structure (e.g., crevices) can provide shelter from predation for benthic invertebrates. To examine effects of natural and artificial structure on the abundance of intertidal juvenile crabs, 2 experiments were conducted in Kingston Bay, Massachusetts, USA, from July to September, 2012. In the first experiment, structure was manipulated in a two-factor design that was placed in the high intertidal for 3 one-week periods to test for both substrate type (sand vs. rock) and the presence or absence of artificial structure (mesh grow-out bags used in aquaculture, ∼0.5 m(2) with 62 mm(2) mesh openings). The Asian shore crab, Hemigrapsus sanguineus, and small individuals of the green crab, Carcinus maenas, were observed only in the treatments of rocks and mesh bag plus rocks. Most green crabs were small (<6 mm in carapace width) whereas H. sanguineus occurred in a wide range of sizes. In the second experiment, 3 levels of oyster-shell treatments were established using grow-out bags placed on a muddy sand substrate in the low intertidal zone: mesh grow-out bags without shells, grow-out bags with oyster shells, and grow-out bags containing live oysters. Replicate bags were deployed weekly for 7 weeks in a randomized complete block design. All crabs collected in the bags were juvenile C. maenas (1-15 mm carapace width), and numbers of crabs differed 6-fold among treatments, with most crabs present in bags with live oysters (29.5 ± 10.6 m(-2) [mean ± S.D.]) and fewest in bags without shells (4.9 ± 3.7 m(-2)). Both C. maenas and H. sanguineus occurred in habitats with natural structure (cobble rocks). The attraction of juvenile C. maenas to artificial structure consisting of plastic mesh bags containing both oyster shells and living oysters could potentially impact oyster aquaculture operations.

  14. Abundance of non-native crabs in intertidal habitats of New England with natural and artificial structure.

    PubMed

    Lovely, Christina M; O'Connor, Nancy J; Judge, Michael L

    2015-01-01

    Marine habitats containing complex physical structure (e.g., crevices) can provide shelter from predation for benthic invertebrates. To examine effects of natural and artificial structure on the abundance of intertidal juvenile crabs, 2 experiments were conducted in Kingston Bay, Massachusetts, USA, from July to September, 2012. In the first experiment, structure was manipulated in a two-factor design that was placed in the high intertidal for 3 one-week periods to test for both substrate type (sand vs. rock) and the presence or absence of artificial structure (mesh grow-out bags used in aquaculture, ∼0.5 m(2) with 62 mm(2) mesh openings). The Asian shore crab, Hemigrapsus sanguineus, and small individuals of the green crab, Carcinus maenas, were observed only in the treatments of rocks and mesh bag plus rocks. Most green crabs were small (<6 mm in carapace width) whereas H. sanguineus occurred in a wide range of sizes. In the second experiment, 3 levels of oyster-shell treatments were established using grow-out bags placed on a muddy sand substrate in the low intertidal zone: mesh grow-out bags without shells, grow-out bags with oyster shells, and grow-out bags containing live oysters. Replicate bags were deployed weekly for 7 weeks in a randomized complete block design. All crabs collected in the bags were juvenile C. maenas (1-15 mm carapace width), and numbers of crabs differed 6-fold among treatments, with most crabs present in bags with live oysters (29.5 ± 10.6 m(-2) [mean ± S.D.]) and fewest in bags without shells (4.9 ± 3.7 m(-2)). Both C. maenas and H. sanguineus occurred in habitats with natural structure (cobble rocks). The attraction of juvenile C. maenas to artificial structure consisting of plastic mesh bags containing both oyster shells and living oysters could potentially impact oyster aquaculture operations. PMID:26401456

  15. Abundance of non-native crabs in intertidal habitats of New England with natural and artificial structure

    PubMed Central

    Lovely, Christina M.; Judge, Michael L.

    2015-01-01

    Marine habitats containing complex physical structure (e.g., crevices) can provide shelter from predation for benthic invertebrates. To examine effects of natural and artificial structure on the abundance of intertidal juvenile crabs, 2 experiments were conducted in Kingston Bay, Massachusetts, USA, from July to September, 2012. In the first experiment, structure was manipulated in a two-factor design that was placed in the high intertidal for 3 one-week periods to test for both substrate type (sand vs. rock) and the presence or absence of artificial structure (mesh grow-out bags used in aquaculture, ∼0.5 m2 with 62 mm2 mesh openings). The Asian shore crab, Hemigrapsus sanguineus, and small individuals of the green crab, Carcinus maenas, were observed only in the treatments of rocks and mesh bag plus rocks. Most green crabs were small (<6 mm in carapace width) whereas H. sanguineus occurred in a wide range of sizes. In the second experiment, 3 levels of oyster-shell treatments were established using grow-out bags placed on a muddy sand substrate in the low intertidal zone: mesh grow-out bags without shells, grow-out bags with oyster shells, and grow-out bags containing live oysters. Replicate bags were deployed weekly for 7 weeks in a randomized complete block design. All crabs collected in the bags were juvenile C. maenas (1–15 mm carapace width), and numbers of crabs differed 6-fold among treatments, with most crabs present in bags with live oysters (29.5 ± 10.6 m−2 [mean ± S.D.]) and fewest in bags without shells (4.9 ± 3.7 m−2). Both C. maenas and H. sanguineus occurred in habitats with natural structure (cobble rocks). The attraction of juvenile C. maenas to artificial structure consisting of plastic mesh bags containing both oyster shells and living oysters could potentially impact oyster aquaculture operations. PMID:26401456

  16. Active sensors for health monitoring of aging aerospace structures

    SciTech Connect

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

    2000-03-08

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

  17. Active sensors for health monitoring of aging aerospace structures

    SciTech Connect

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

    2000-02-29

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

  18. Spatiotemporal Changes in the Structure and Composition of a Less-Abundant Bacterial Phylum (Planctomycetes) in Two Perialpine Lakes ▿ †

    PubMed Central

    Pollet, Thomas; Tadonléké, Rémy D.; Humbert, Jean François

    2011-01-01

    We used fingerprinting and cloning-sequencing to study the spatiotemporal dynamics and diversity of Planctomycetes in two perialpine lakes with contrasting environmental conditions. Planctomycetes, which are less-abundant bacteria in freshwater ecosystems, appeared to be structured in the same way as the entire bacterial community in these ecosystems. They were more diversified and displayed fewer temporal variations in the hypolimnia than in the epilimnia. Like the more-abundant bacterial groups in aquatic systems, Planctomycetes communities seem to be composed of a very small number of abundant and widespread operational taxonomic units (OTUs) and a large number of OTUs that are present at low abundance. This indicates that the concept of “abundant or core” and “rare” bacterial phylotypes could also be applied to less-abundant freshwater bacterial phyla. The richness and diversity of Planctomycetes were mainly driven by pH and were similar in both of the lakes studied, whereas the composition of the Planctomycetes community seemed to be determined by a combination of factors including temperature, pH, and nutrients. The relative abundances of the dominant OTUs varied over time and were differently associated with abiotic factors. Our findings demonstrate that less-abundant bacterial phyla, such as Planctomycetes, can display strong spatial and seasonal variations linked to environmental conditions and suggest that their functional role in the lakes studied might be attributable mainly to a small number of phylotypes and vary over space and time in the water column. PMID:21602381

  19. Bioinformatics Analysis Reveals Abundant Short Alpha-Helices as a Common Structural Feature of Oomycete RxLR Effector Proteins

    PubMed Central

    Ye, Wenwu; Wang, Yang; Wang, Yuanchao

    2015-01-01

    RxLR effectors represent one of the largest and most diverse effector families in oomycete plant pathogens. These effectors have attracted enormous attention since they can be delivered inside the plant cell and manipulates host immunity. With the exceptions of a signal peptide and the following RxLR-dEER and C-terminal W/Y/L motifs identified from the sequences themselves, nearly no functional domains have been found. Recently, protein structures of several RxLRs were revealed to comprise alpha-helical bundle repeats. However, approximately half of all RxLRs lack obvious W/Y/L motifs, which are associated with helical structures. In this study, secondary structure prediction of the putative RxLR proteins was performed. We found that the C-terminus of the majority of these RxLR proteins, irrespective of the presence of W/Y/L motifs, contains abundant short alpha-helices. Since a large-scale experimental determination of protein structures has been difficult to date, results of the current study extend our understanding on the oomycete RxLR effectors in protein secondary structures from individual members to the entire family. Moreover, we identified less alpha-helix-rich proteins from secretomes of several oomycete and fungal organisms in which RxLRs have not been identified, providing additional evidence that these organisms are unlikely to harbor RxLR-like proteins. Therefore, these results provide additional information that will aid further studies on the evolution and functional mechanisms of RxLR effectors. PMID:26252511

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  1. Aging effects on the structure underlying balance abilities tests.

    PubMed

    Urushihata, Toshiya; Kinugasa, Takashi; Soma, Yuki; Miyoshi, Hirokazu

    2010-01-01

    Balance impairment is one of the biggest risk factors for falls reducing inactivity, resulting in nursing care. Therefore, balance ability is crucial to maintain the activities of independent daily living of older adults. Many tests to assess balance ability have been developed. However, few reports reveal the structure underlying results of balance performance tests comparing young and older adults. Covariance structure analysis is a tool that is used to test statistically whether factorial structure fits data. This study examined aging effects on the factorial structure underlying balance performance tests. Participants comprised 60 healthy young women aged 22 ± 3 years (young group) and 60 community-dwelling older women aged 69 ± 5 years (older group). Six balance tests: postural sway, one-leg standing, functional reach, timed up and go (TUG), gait, and the EquiTest were employed. Exploratory factor analysis revealed that three clearly interpretable factors were extracted in the young group. The first factor had high loadings on the EquiTest, and was interpreted as 'Reactive'. The second factor had high loadings on the postural sway test, and was interpreted as 'Static'. The third factor had high loadings on TUG and gait test, and was interpreted as 'Dynamic'. Similarly, three interpretable factors were extracted in the older group. The first factor had high loadings on the postural sway test and the EquiTest and therefore was interpreted as 'Static and Reactive'. The second factor, which had high loadings on the EquiTest, was interpreted as 'Reactive'. The third factor, which had high loadings on TUG and the gait test, was interpreted as 'Dynamic'. A covariance structure model was applied to the test data: the second-order factor was balance ability, and the first-order factors were static, dynamic and reactive factors which were assumed to be measured based on the six balance tests. Goodness-of-fit index (GFI) of the models were acceptable (young group, GFI

  2. Aging Effects on the Structure Underlying Balance Abilities Tests

    PubMed Central

    Kinugasa, Takashi; Soma, Yuki; Miyoshi, Hirokazu

    2010-01-01

    Balance impairment is one of the biggest risk factors for falls reducing inactivity, resulting in nursing care. Therefore, balance ability is crucial to maintain the activities of independent daily living of older adults. Many tests to assess balance ability have been developed. However, few reports reveal the structure underlying results of balance performance tests comparing young and older adults. Covariance structure analysis is a tool that is used to test statistically whether factorial structure fits data. This study examined aging effects on the factorial structure underlying balance performance tests. Participants comprised 60 healthy young women aged 22 ± 3 years (young group) and 60 community-dwelling older women aged 69 ± 5 years (older group). Six balance tests: postural sway, one-leg standing, functional reach, timed up and go (TUG), gait, and the EquiTest were employed. Exploratory factor analysis revealed that three clearly interpretable factors were extracted in the young group. The first factor had high loadings on the EquiTest, and was interpreted as ‘Reactive’. The second factor had high loadings on the postural sway test, and was interpreted as ‘Static’. The third factor had high loadings on TUG and gait test, and was interpreted as ‘Dynamic’. Similarly, three interpretable factors were extracted in the older group. The first factor had high loadings on the postural sway test and the EquiTest and therefore was interpreted as ‘Static and Reactive’. The second factor, which had high loadings on the EquiTest, was interpreted as ‘Reactive’. The third factor, which had high loadings on TUG and the gait test, was interpreted as ‘Dynamic’. A covariance structure model was applied to the test data: the second-order factor was balance ability, and the first-order factors were static, dynamic and reactive factors which were assumed to be measured based on the six balance tests. Goodness-of-fit index (GFI) of the models were

  3. Evolution of long-lived globular cluster stars. II. Sodium abundance variations on the asymptotic giant branch as a function of globular cluster age and metallicity

    NASA Astrophysics Data System (ADS)

    Charbonnel, Corinne; Chantereau, William

    2016-02-01

    Context. Long-lived stars in globular clusters exhibit chemical peculiarities with respect to their halo counterparts. In particular, sodium-enriched stars are identified as belonging to a second stellar population born from cluster material contaminated by the hydrogen-burning ashes of a first stellar population. Their presence and numbers in different locations of the colour-magnitude diagram provide important constraints on the self-enrichment scenarios. In particular, the ratio of Na-poor to Na-rich stars on the asymptotic giant branch (AGB) has recently been found to vary strongly from cluster to cluster (NGC 6752, 47 Tuc, and NGC 2808), while it is relatively constant on the red giant branch (RGB). Aims: We investigate the impact of both age and metallicity on the theoretical sodium spread along the AGB within the framework of the fast rotating massive star (FRMS) scenario for globular cluster self-enrichment. Methods: We computed evolution models of low-mass stars for four different metallicities ([Fe/H] = -2.2, -1.75, -1.15, -0.5) assuming the initial helium-sodium abundance correlation for second population stars derived from the FRMS models and using mass loss prescriptions on the RGB with two realistic values of the free parameter in the Reimers formula. Results: Based on this grid of models we derive the theoretical critical initial mass for a star born with a given helium, sodium, and metal content that determines whether that star will climb or not the AGB. This allows us to predict the maximum sodium content expected on the AGB for globular clusters as a function of both their metallicity and age. We find that (1) at a given metallicity, younger clusters are expected to host AGB stars exhibiting a larger sodium spread than older clusters and (2) at a given age, higher sodium dispersion along the AGB is predicted in the most metal-poor globular clusters than in the metal-rich ones. We also confirm the strong impact of the mass loss rate in the earlier

  4. [Relative abundance, population structure, habitat preferences and activity patterns of Tapirus bairdii (Perissodactyla: Tapiridae), in Chimalapas forest, Oaxaca, Mexico].

    PubMed

    Lira-Torres, Iván; Briones-Salas, Miguel; Sánchez-Rojas, Gerardo

    2014-12-01

    Baird's tapir (Tapirus bairdii) is endangered primarily because of habitat loss and fragmentation, and overhunting throughout its distribution range. One of the priority land areas for the conservation of this species is the Northern part of its range in the Chimalapas forest, Oaxaca. The aim of this research was to determine the relative abundance, population struc- ture, habitat preferences and activity patterns of Baird's tapir (Tapirus bairdii) in the Chimalapas forest, Oaxaca, Mexico, through the non-invasive technique of camera-trap sampling. A total of five sampling sessions were undertaken among 2009-2013, and used a total of 30 camera-traps in each period. The determinant factor of the sampling design was the hunting between two study areas. A total sampling effort of 9000 trap-days allowed to estimate an index of relative abundance (IRA) of 6.77 tapir photographs/1,000 trap-days (n = 61). IRA varied significantly between sampling stations (Mann-Whitney, p < 0.01). The frequency of Baird's tapir photos was higher in the dry season in tropical rain forest without hunting (χ2, p < 0.5). In the rainy season, the tropical rain forest and secondary vegetation habitats showed higher photo frequency than expected from random (χ2, p < 0.5). Considering population structure, a 95.08% of adult animals was obtained in photographic records (n = 58). Three types of activity pattern were observed, with more nocturnal records (88.33%; Kruskal-Wallis, p < 0.05). The Chimalapas forest appears to be the second most important terrestrial priority ecoregion, just after the Mayan Forest (Campeche, Chiapas, Quintana Roo), for the conservation of tapir populations, not only for Mexico but also for Central America. PMID:25720176

  5. [Relative abundance, population structure, habitat preferences and activity patterns of Tapirus bairdii (Perissodactyla: Tapiridae), in Chimalapas forest, Oaxaca, Mexico].

    PubMed

    Lira-Torres, Iván; Briones-Salas, Miguel; Sánchez-Rojas, Gerardo

    2014-12-01

    Baird's tapir (Tapirus bairdii) is endangered primarily because of habitat loss and fragmentation, and overhunting throughout its distribution range. One of the priority land areas for the conservation of this species is the Northern part of its range in the Chimalapas forest, Oaxaca. The aim of this research was to determine the relative abundance, population struc- ture, habitat preferences and activity patterns of Baird's tapir (Tapirus bairdii) in the Chimalapas forest, Oaxaca, Mexico, through the non-invasive technique of camera-trap sampling. A total of five sampling sessions were undertaken among 2009-2013, and used a total of 30 camera-traps in each period. The determinant factor of the sampling design was the hunting between two study areas. A total sampling effort of 9000 trap-days allowed to estimate an index of relative abundance (IRA) of 6.77 tapir photographs/1,000 trap-days (n = 61). IRA varied significantly between sampling stations (Mann-Whitney, p < 0.01). The frequency of Baird's tapir photos was higher in the dry season in tropical rain forest without hunting (χ2, p < 0.5). In the rainy season, the tropical rain forest and secondary vegetation habitats showed higher photo frequency than expected from random (χ2, p < 0.5). Considering population structure, a 95.08% of adult animals was obtained in photographic records (n = 58). Three types of activity pattern were observed, with more nocturnal records (88.33%; Kruskal-Wallis, p < 0.05). The Chimalapas forest appears to be the second most important terrestrial priority ecoregion, just after the Mayan Forest (Campeche, Chiapas, Quintana Roo), for the conservation of tapir populations, not only for Mexico but also for Central America.

  6. Capella: Structure and Abundances

    NASA Technical Reports Server (NTRS)

    Brickhouse, Nancy S.

    1997-01-01

    The analysis of the Advanced Satellite for Cosmology and Astrophysics (ASCA) spectra of the cool star binary system Capella is reported. The results of EUVE analysis, ASCA analysis, application of EUVE model to ASCA analysis, and Uncertainty Analysis are discussed.

  7. Age and structure of a model vapour-deposited glass

    PubMed Central

    Reid, Daniel R.; Lyubimov, Ivan; Ediger, M. D.; de Pablo, Juan J.

    2016-01-01

    Glass films prepared by a process of physical vapour deposition have been shown to have thermodynamic and kinetic stability comparable to those of ordinary glasses aged for thousands of years. A central question in the study of vapour-deposited glasses, particularly in light of new knowledge regarding anisotropy in these materials, is whether the ultra-stable glassy films formed by vapour deposition are ever equivalent to those obtained by liquid cooling. Here we present a computational study of vapour deposition for a two-dimensional glass forming liquid using a methodology, which closely mimics experiment. We find that for the model considered here, structures that arise in vapour-deposited materials are statistically identical to those observed in ordinary glasses, provided the two are compared at the same inherent structure energy. We also find that newly deposited hot molecules produce cascades of hot particles that propagate far into the film, possibly influencing the relaxation of the material. PMID:27762262

  8. Abundance and Community Structure of Bacteria on Asian Dust Particles Collected in Beijing, China, during the Asian Dust Season.

    PubMed

    Yamaguchi, Nobuyasu; Baba, Takashi; Ichijo, Tomoaki; Himezawa, Yuka; Enoki, Kanami; Saraya, Makoto; Li, Pin-Fang; Nasu, Masao

    2016-01-01

    Approximately 180 t/km(2) of Asian dust particles are estimated to fall annually on Beijing, China, and there is significant concern about the influence of microbes transported by Asian dust events on human health and downwind ecosystems. In this study, we collected Asian dust particles in Beijing, and analyzed the bacterial communities on these particles by culture-independent methods. Bacterial cells on Asian dust particles were visualized first by laser scanning microscopy, which demonstrated that Asian dust particles carry bacterial cells to Beijing. Bacterial abundance, as determined by quantitative polymerase chain reaction (PCR), was 10(8) to 10(9) cells/g, a value about 10 times higher than that in Asian dust source soils. Inter-seasonal variability of bacterial community structures among Asian dust samples, as compared by terminal restriction fragment length polymorphism (T-RFLP), was low during the Asian dust season. Several viable bacteria, including intestinal bacteria, were found in Asian dust samples by denaturing gradient gel electrophoresis (DGGE). Clone library analysis targeting 16S ribosomal RNA (rRNA) gene sequences demonstrated that bacterial phylogenetic diversity was high in the dust samples, and most of these were environmental bacteria distributed in soil and air. The dominant species in the clone library was Segetibacter aerophilus (Bacteroidetes), which was first isolated from an Asian dust sample collected in Korea. Our results also indicate the possibility of a change in the bacterial community structure during transportation and increases in desiccation-tolerant bacteria such as Firmicutes.

  9. Birth history, age structure, and post World War II fertility in ten developed countries: an exploratory empirical analysis.

    PubMed

    Artzrouni, M A; Easterlin, R A

    1982-01-01

    A post World War 2 swing in fertility occurred in many industrialized countries. Research focusing chiefly on the US has suggested that a country's prior birth history has, through its effects on age structure, been an important cause of this fertility swing. The reasoning is that the pre-World War 2 depression in fertility and post World War 2 baby boom produced after 1945 1st a scarcity and then an abundance of those in family-forming ages relative to older adults. The relative scarcity of young adults, in turn, created favorable economic and psychological conditions among those in child bearing ages and promoted marriage and child bearing; the relative abundance had the opposite effect. This paper examines the relation between birth history and fertility from 1951-76 in England, Wales, France, Netherlands, Sweden, Finland, Denmark, Switzerland, Spain, Italy, and the US and explores the implications of the analysis for experience in the remainder of this century. The analysis builds on the well-known proposition that age structure is primarily determined by a country's birth history. Birth data can be thought of as yielding an imputed age ratio, that which would prevail in the absence of mortality and migration. Analysis of data indicates that the pattern of change in the imputed ratio usually approximates fairly closely that in the actual ratio. A ratio of old to young can be thought of as consisting of an upper age limit, lower age limit, and an intermediate age that divides the population into young and old. With all 3 of these ages free to vary, a computer program then determines within certain constraints which of all possible imputed ratios of old to young has the highest (positive or negative) correlation with the total fertility rate from 1951-76. In all countries except Italy the results support the hypothesis that a scarcity of adults in the younger adult ages relative to those in older ages leads to a relatively high total fertility rate; a relative

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

    SciTech Connect

    Ellingwood, B.; Song, J.

    1996-03-01

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

  11. Evaluation of the ecotoxicological impact of the organochlorine chlordecone on soil microbial community structure, abundance, and function.

    PubMed

    Merlin, Chloé; Devers, Marion; Béguet, Jérémie; Boggio, Baptiste; Rouard, Nadine; Martin-Laurent, Fabrice

    2016-03-01

    The insecticide chlordecone applied for decades in banana plantations currently contaminates 20,000 ha of arable land in the French West Indies. Although the impact of various pesticides on soil microorganisms has been studied, chlordecone toxicity to the soil microbial community has never been assessed. We investigated in two different soils (sandy loam and silty loam) exposed to different concentrations of CLD (D0, control; D1 and D10, 1 and 10 times the agronomical dose) over different periods of time (3, 7, and 32 days): (i) the fate of chlordecone by measuring (14)C-chlordecone mass balance and (ii) the impact of chlordecone on microbial community structure, abundance, and function, using standardized methods (-A-RISA, taxon-specific quantitative PCR (qPCR), and (14)C-compounds mineralizing activity). Mineralization of (14)C-chlordecone was inferior below 1 % of initial (14)C-activity. Less than 2 % of (14)C-activity was retrieved from the water-soluble fraction, while most of it remained in the organic-solvent-extractable fraction (75 % of initial (14)C-activity). Only 23 % of the remaining (14)C-activity was measured in nonextractable fraction. The fate of chlordecone significantly differed between the two soils. The soluble and nonextractable fractions were significantly higher in sandy loam soil than in silty loam soil. All the measured microbiological parameters allowed discriminating statistically the two soils and showed a variation over time. The genetic structure of the bacterial community remained insensitive to chlordecone exposure in silty loam soil. In response to chlordecone exposure, the abundance of Gram-negative bacterial groups (β-, γ-Proteobacteria, Planctomycetes, and Bacteroidetes) was significantly modified only in sandy loam soil. The mineralization of (14)C-sodium acetate and (14)C-2,4-D was insensitive to chlordecone exposure in silty loam soil. However, mineralization of (14)C-sodium acetate was significantly reduced in soil

  12. Group 3 late embryogenesis abundant proteins from embryos of Artemia franciscana: structural properties and protective abilities during desiccation.

    PubMed

    Boswell, Leaf C; Menze, Michael A; Hand, Steven C

    2014-01-01

    Group 3 late embryogenesis abundant (LEA) proteins are highly hydrophilic, and their expression is associated with desiccation tolerance in both plants and animals. Here we show that two LEA proteins from embryos of Artemia franciscana, AfrLEA2 and AfrLEA3m, are intrinsically disordered in solution but upon desiccation gain secondary structure, as measured by circular dichroism. Trifluoroethanol and sodium dodecyl sulfate are both shown to induce α-helical structure in AfrLEA2 and AfrLEA3m. Bioinformatic predictions of secondary-structure content for both proteins correspond most closely to conformations measured in the dry state. Because some LEA proteins afford protection to desiccation-sensitive proteins during drying and subsequent rehydration, we tested for this capacity in AfrLEA2 and AfrLEA3m. The protective capacities vary, depending on the target enzyme. For the cytoplasmic enzyme lactate dehydrogenase, neither AfrLEA2 nor AfrLEA3m, with or without trehalose present, was able to afford protection better than that provided by bovine serum albumin (BSA) under the same conditions. However, for another cytoplasmic enzyme, phosphofructokinase, both AfrLEA2 and AfrLEA3m in the presence of trehalose were able to afford protection far greater than that provided by BSA with trehalose. Finally, for the mitochondrial enzyme citrate synthase, 400-μg/mL AfrLEA3m without trehalose provided significantly more protection than the same concentration of either AfrLEA2 or BSA. PMID:25244376

  13. The temperature and ionization structure of the emitting gas in HII galaxies: implications for the accuracy of abundance determinations

    NASA Astrophysics Data System (ADS)

    Hägele, Guillermo F.; Pérez-Montero, Enrique; Díaz, Ángeles I.; Terlevich, Elena; Terlevich, Roberto

    2006-10-01

    We propose a methodology to perform a self-consistent analysis of the physical properties of the emitting gas of HII galaxies adequate to the data that can be obtained with the 21st century technology. This methodology requires the production and calibration of empirical relations between the different line temperatures that should supersede currently used ones based on very simple, and poorly tested, photoionization model sequences. As a first step to reach these goals, we have obtained simultaneous blue to far red long-slit spectra with the William Herschel Telescope (WHT) of three compact HII galaxies selected from the Sloan Digital Sky Survey (SDSS) Data Release 2 (DR2) spectral catalogue using the INAOE Virtual Observatory superserver. Our spectra cover the range from 3200 to 10500Å, including the Balmer jump, the [OII]λλ3727, 29Å lines, the [SIII]λλ9069, 9532Å doublet as well as various weak auroral lines such as [OIII]λ4363Å and [SIII]λ6312Å. For the three objects, we have measured at least four line temperatures, T([OIII]), T([SIII]), T([OII]) and T([SII]), and the Balmer continuum temperature T(Bac). These measurements and a careful and realistic treatment of the observational errors yield total oxygen abundances with accuracies between 5 and 9 per cent. These accuracies are expected to improve as better calibrations based on more precise measurements, both on electron temperatures and densities, are produced. We have compared our obtained spectra with those downloaded from the SDSS DR3 finding a satisfactory agreement. The analysis of these spectra yields values of line temperatures and elemental ionic and total abundances which are in general agreement with those derived from the WHT spectra, although for most quantities they can only be taken as estimates since, due to the lack of direct measurements of the required lines, theoretical models had to be used whose uncertainties are impossible to quantify. The ionization structure found for the

  14. Spatial and temporal variation in the abundance, distribution and population structure of epibenthic megafauna in Port Foster, Deception Island

    NASA Astrophysics Data System (ADS)

    Cranmer, T. L.; Ruhl, H. A.; Baldwin, R. J.; Kaufmann, R. S.

    2003-06-01

    Abundance and spatial distribution of epibenthic megafauna were examined at Port Foster, Deception Island, five times between March 1999 and November 2000. Camera sled surveys and bottom trawls were used to identify and collect specimens, and camera sled photographs also were used to determine abundances and spatial distributions for each species. The ophiuroid Ophionotus victoriae, the regular echinoid Sterechinus neumayeri, and one or more species of Porifera were the most abundant taxa during this sampling period. Abundances of O. victoriae varied throughout the annual cycle, peaking in June 2000, and were correlated positively with sedimentation rates. In contrast, abundances of S. neumayeri were consistent throughout the sampling period, except for a peak in June 2000, during austral winter. Peak abundances for both species coincided with a large number of small individuals, indicating apparent recruitment events for O. victoriae and S. neumayeri during this time period. Poriferans, as a group, had statistically similar abundances during each sampling period. Low-abundance species tended to be aggregated on both small and large spatial scales, their distributions probably influenced by reproductive method, gregarious settlement, and food availability. The spatial distribution of S. neumayeri in June 2000 and O. victoriae was random across multiple spatial scales, perhaps in response to food availability and broad environmental tolerances, respectively.

  15. Multiple endemic states in age-structured SIR epidemic models.

    PubMed

    Franceschetti, Andrea; Pugliese, Andrea; Breda, Dmitri

    2012-07-01

    SIR age-structured models are very often used as a basic model of epidemic spread. Yet, their behaviour, under generic assumptions on contact rates between different age classes, is not completely known, and, in the most detailed analysis so far, Inaba (1990) was able to prove uniqueness of the endemic equilibrium only under a rather restrictive condition. Here, we show an example in the form of a 3x3 contact matrix in which multiple non-trivial steady states exist. This instance of non-uniqueness of positive equilibria differs from most existing ones for epidemic models, since it arises not from a backward transcritical bifurcation at the disease free equilibrium, but through two saddle-node bifurcations of the positive equilibrium. The dynamical behaviour of the model is analysed numerically around the range where multiple endemic equilibria exist; many other features are shown to occur, from coexistence of multiple attractive periodic solutions, some with extremely long period, to quasi-periodic and chaotic attractors. It is also shown that, if the contact rates are in the form of a 2x2 WAIFW matrix, uniqueness of non-trivial steady states always holds, so that 3 is the minimum dimension of the contact matrix to allow for multiple endemic equilibria.

  16. Accounting for Subgroup Structure in Line-Transect Abundance Estimates of False Killer Whales (Pseudorca crassidens) in Hawaiian Waters

    PubMed Central

    Bradford, Amanda L.; Forney, Karin A.; Oleson, Erin M.; Barlow, Jay

    2014-01-01

    For biological populations that form aggregations (or clusters) of individuals, cluster size is an important parameter in line-transect abundance estimation and should be accurately measured. Cluster size in cetaceans has traditionally been represented as the total number of individuals in a group, but group size may be underestimated if group members are spatially diffuse. Groups of false killer whales (Pseudorca crassidens) can comprise numerous subgroups that are dispersed over tens of kilometers, leading to a spatial mismatch between a detected group and the theoretical framework of line-transect analysis. Three stocks of false killer whales are found within the U.S. Exclusive Economic Zone of the Hawaiian Islands (Hawaiian EEZ): an insular main Hawaiian Islands stock, a pelagic stock, and a Northwestern Hawaiian Islands (NWHI) stock. A ship-based line-transect survey of the Hawaiian EEZ was conducted in the summer and fall of 2010, resulting in six systematic-effort visual sightings of pelagic (n = 5) and NWHI (n = 1) false killer whale groups. The maximum number and spatial extent of subgroups per sighting was 18 subgroups and 35 km, respectively. These sightings were combined with data from similar previous surveys and analyzed within the conventional line-transect estimation framework. The detection function, mean cluster size, and encounter rate were estimated separately to appropriately incorporate data collected using different methods. Unlike previous line-transect analyses of cetaceans, subgroups were treated as the analytical cluster instead of groups because subgroups better conform to the specifications of line-transect theory. Bootstrap values (n = 5,000) of the line-transect parameters were randomly combined to estimate the variance of stock-specific abundance estimates. Hawai’i pelagic and NWHI false killer whales were estimated to number 1,552 (CV = 0.66; 95% CI = 479–5,030) and 552 (CV = 1.09; 95% CI = 97–3

  17. Accounting for subgroup structure in line-transect abundance estimates of false killer whales (Pseudorca crassidens) in Hawaiian waters.

    PubMed

    Bradford, Amanda L; Forney, Karin A; Oleson, Erin M; Barlow, Jay

    2014-01-01

    For biological populations that form aggregations (or clusters) of individuals, cluster size is an important parameter in line-transect abundance estimation and should be accurately measured. Cluster size in cetaceans has traditionally been represented as the total number of individuals in a group, but group size may be underestimated if group members are spatially diffuse. Groups of false killer whales (Pseudorca crassidens) can comprise numerous subgroups that are dispersed over tens of kilometers, leading to a spatial mismatch between a detected group and the theoretical framework of line-transect analysis. Three stocks of false killer whales are found within the U.S. Exclusive Economic Zone of the Hawaiian Islands (Hawaiian EEZ): an insular main Hawaiian Islands stock, a pelagic stock, and a Northwestern Hawaiian Islands (NWHI) stock. A ship-based line-transect survey of the Hawaiian EEZ was conducted in the summer and fall of 2010, resulting in six systematic-effort visual sightings of pelagic (n = 5) and NWHI (n = 1) false killer whale groups. The maximum number and spatial extent of subgroups per sighting was 18 subgroups and 35 km, respectively. These sightings were combined with data from similar previous surveys and analyzed within the conventional line-transect estimation framework. The detection function, mean cluster size, and encounter rate were estimated separately to appropriately incorporate data collected using different methods. Unlike previous line-transect analyses of cetaceans, subgroups were treated as the analytical cluster instead of groups because subgroups better conform to the specifications of line-transect theory. Bootstrap values (n = 5,000) of the line-transect parameters were randomly combined to estimate the variance of stock-specific abundance estimates. Hawai'i pelagic and NWHI false killer whales were estimated to number 1,552 (CV = 0.66; 95% CI = 479-5,030) and 552 (CV = 1.09; 95% CI = 97

  18. Accounting for subgroup structure in line-transect abundance estimates of false killer whales (Pseudorca crassidens) in Hawaiian waters.

    PubMed

    Bradford, Amanda L; Forney, Karin A; Oleson, Erin M; Barlow, Jay

    2014-01-01

    For biological populations that form aggregations (or clusters) of individuals, cluster size is an important parameter in line-transect abundance estimation and should be accurately measured. Cluster size in cetaceans has traditionally been represented as the total number of individuals in a group, but group size may be underestimated if group members are spatially diffuse. Groups of false killer whales (Pseudorca crassidens) can comprise numerous subgroups that are dispersed over tens of kilometers, leading to a spatial mismatch between a detected group and the theoretical framework of line-transect analysis. Three stocks of false killer whales are found within the U.S. Exclusive Economic Zone of the Hawaiian Islands (Hawaiian EEZ): an insular main Hawaiian Islands stock, a pelagic stock, and a Northwestern Hawaiian Islands (NWHI) stock. A ship-based line-transect survey of the Hawaiian EEZ was conducted in the summer and fall of 2010, resulting in six systematic-effort visual sightings of pelagic (n = 5) and NWHI (n = 1) false killer whale groups. The maximum number and spatial extent of subgroups per sighting was 18 subgroups and 35 km, respectively. These sightings were combined with data from similar previous surveys and analyzed within the conventional line-transect estimation framework. The detection function, mean cluster size, and encounter rate were estimated separately to appropriately incorporate data collected using different methods. Unlike previous line-transect analyses of cetaceans, subgroups were treated as the analytical cluster instead of groups because subgroups better conform to the specifications of line-transect theory. Bootstrap values (n = 5,000) of the line-transect parameters were randomly combined to estimate the variance of stock-specific abundance estimates. Hawai'i pelagic and NWHI false killer whales were estimated to number 1,552 (CV = 0.66; 95% CI = 479-5,030) and 552 (CV = 1.09; 95% CI = 97

  19. Ecosystem size structure response to 21st century climate projection: large fish abundance decreases in the central North Pacific and increases in the California Current.

    PubMed

    Woodworth-Jefcoats, Phoebe A; Polovina, Jeffrey J; Dunne, John P; Blanchard, Julia L

    2013-03-01

    Output from an earth system model is paired with a size-based food web model to investigate the effects of climate change on the abundance of large fish over the 21st century. The earth system model, forced by the Intergovernmental Panel on Climate Change (IPCC) Special report on emission scenario A2, combines a coupled climate model with a biogeochemical model including major nutrients, three phytoplankton functional groups, and zooplankton grazing. The size-based food web model includes linkages between two size-structured pelagic communities: primary producers and consumers. Our investigation focuses on seven sites in the North Pacific, each highlighting a specific aspect of projected climate change, and includes top-down ecosystem depletion through fishing. We project declines in large fish abundance ranging from 0 to 75.8% in the central North Pacific and increases of up to 43.0% in the California Current (CC) region over the 21st century in response to change in phytoplankton size structure and direct physiological effects. We find that fish abundance is especially sensitive to projected changes in large phytoplankton density and our model projects changes in the abundance of large fish being of the same order of magnitude as changes in the abundance of large phytoplankton. Thus, studies that address only climate-induced impacts to primary production without including changes to phytoplankton size structure may not adequately project ecosystem responses.

  20. Inferring Selection Intensity and Allele Age from Multilocus Haplotype Structure

    PubMed Central

    Chen, Hua; Slatkin, Montgomery

    2013-01-01

    It is a challenging task to infer selection intensity and allele age from population genetic data. Here we present a method that can efficiently estimate selection intensity and allele age from the multilocus haplotype structure in the vicinity of a segregating mutant under positive selection. We use a structured-coalescent approach to model the effect of directional selection on the gene genealogies of neutral markers linked to the selected mutant. The frequency trajectory of the selected allele follows the Wright-Fisher model. Given the position of the selected mutant, we propose a simplified multilocus haplotype model that can efficiently model the dynamics of the ancestral haplotypes under the joint influence of selection and recombination. This model approximates the ancestral genealogies of the sample, which reduces the number of states from an exponential function of the number of single-nucleotide polymorphism loci to a quadratic function. That allows parameter inference from data covering DNA regions as large as several hundred kilo-bases. Importance sampling algorithms are adopted to evaluate the probability of a sample by exploring the space of both allele frequency trajectories of the selected mutation and gene genealogies of the linked sites. We demonstrate by simulation that the method can accurately estimate selection intensity for moderate and strong positive selection. We apply the method to a data set of the G6PD gene in an African population and obtain an estimate of 0.0456 (95% confidence interval 0.0144−0.0769) for the selection intensity. The proposed method is novel in jointly modeling the multilocus haplotype pattern caused by recombination and mutation, allowing the analysis of haplotype data in recombining regions. Moreover, the method is applicable to data from populations under exponential growth and a variety of other demographic histories. PMID:23797107

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

    USGS Publications Warehouse

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

    2001-01-01

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

  2. Douglas-fir forests in the Cascade Mountains of Oregon and Washington: is the abundance of small mammals related to stand age and moisture?

    USGS Publications Warehouse

    Coen, P.S.; Bury, R.B.; Spies, T.A.

    1988-01-01

    Red tree voles (Arborimus longicaudus) were the only small mammal strongly associated with old-growth forests, whereas vagrant shrews (Sorex vagrans) were most abundant in young forests. Pacific marsh shrews (S. bendirii) were most abundant in wet old-growth forests, but abundance of this species in young (wet) forests needs further study. Clearcuts had a mammalian fauna distinct from young forest stands. Abundance of several species was correlated to habitat features unique to naturally regenerated forests, indicated an urgent need to study the long-term effects of forest management to nongame wildlife.

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

    NASA Astrophysics Data System (ADS)

    Attard, Guillaume; Rossier, Yvan; Eisenlohr, Laurent

    2016-04-01

    In this paper, underground structures are shown to have a major influence on the groundwater mean age distribution described as a dispersive piston effect. Urban underground development does not occur without impacts on subsoil resources. In particular, groundwater resources can be vulnerable and generate disturbances when this space is exploited. Groundwater age spatial distribution data are fundamental for resource management as it can provide operational sustainability indicators. However, the application of groundwater age modeling is neglected regarding the potential effect of underground structures in urban areas. A three dimensional modeling approach was conducted to quantify the impact of two underground structures: (1) an impervious structure and (2) a draining structure. Both structures are shown to cause significant mixing processes occurring between shallow and deeper aquifers. The design technique used for draining structures is shown to have the greatest impact, generating a decrease in mean age of more than 80% under the structure. Groundwater age modeling is shown to be relevant for highlighting the role played by underground structures in advective-dispersive flows in urban areas.

  4. Biochemical and structural characterization of an endoplasmic reticulum-localized late embryogenesis abundant (LEA) protein from the liverwort Marchantia polymorpha.

    PubMed

    Hatanaka, Rie; Furuki, Takao; Shimizu, Tempei; Takezawa, Daisuke; Kikawada, Takahiro; Sakurai, Minoru; Sugawara, Yasutake

    2014-11-28

    Late embryogenesis abundant (LEA) proteins, which accumulate to high levels in seeds during late maturation, are associated with desiccation tolerance. A member of the LEA protein family was found in cultured cells of the liverwort Marchantia polymorpha; preculture treatment of these cells with 0.5M sucrose medium led to their acquisition of desiccation tolerance. We characterized this preculture-induced LEA protein, designated as MpLEA1. MpLEA1 is predominantly hydrophilic with a few hydrophobic residues that may represent its putative signal peptide. The protein also contains a putative endoplasmic reticulum (ER) retention sequence, HEEL, at the C-terminus. Microscopic observations indicated that GFP-fused MpLEA1 was mainly localized in the ER. The recombinant protein MpLEA1 is intrinsically disordered in solution. On drying, MpLEA1 shifted predominantly toward α-helices from random coils. Such changes in conformation are a typical feature of the group 3 LEA proteins. Recombinant MpLEA1 prevented the aggregation of α-casein during desiccation-rehydration events, suggesting that MpLEA1 exerts anti-aggregation activity against desiccation-sensitive proteins by functioning as a "molecular shield". Moreover, the anti-aggregation activity of MpLEA1 was ten times greater than that of BSA or insect LEA proteins, which are known to prevent aggregation on drying. Here, we show that an ER-localized LEA protein, MpLEA1, possesses biochemical and structural features specific to group 3 LEA proteins. PMID:25450698

  5. Inconsistent Changes in Microbial Community Structure and Abundance with Biochar Amendment in Rice Paddy Soils from South China

    NASA Astrophysics Data System (ADS)

    Chen, J.; Qu, J.; Liu, X.; Zheng, J.; Li, L.; Pan, G.

    2012-04-01

    Effects of biochar amendment on soil microbiota had not yet been well understood. We conducted a cross site field study on biochar amendment to rice paddies from south China in 2010. The experiment was performed with four treatments including N fertilization only (C0N), N fertilization plus biochar at 20t/ha (C1N) and at 40t/ha (C2N) as well as a control without N fertilization and biochar (C0N0) consistently with three sites. Biochar was spread at soil surface and incorporated into soil and thoroughly mixed to depth of about 12cm before padding for rice seedling transplantation. Rice production was conducted with conventional water and nutrient management practices adapting to local climate and cultivar conditions. Topsoil samples were collected from each treatment plot across sites for chemical properties and molecular analysis after rice harvest in autumn of 2010. Contents of organic carbon, total N as well as soil microbial biomass carbon were determined with recommended methods. Quantitative real-time PCR coupled with 16S rRNA gene and 18S rRNA gene denaturing gradient gel electrophoresis (DGGE) were respectively employed to trace changes in abundance and structure of bacteria and fungi community with biochar amendment. Increase in microbial biomass carbon (SMBC) was not observed in one site but by 10-20% in other two sites while SOC contents were increased by 25-45% in all sites under biochar treatments. Copy numbers of bacterial genes were different between the sites but no changes with biochar treatment in a single site. However, cluster analysis revealed a more or less decreased similarity of bacterial community to the control (ranging from 75% to 85%) by biochar treatment in a single site. Nevertheless, a number of special bands appeared both in bacterial and fungal DGGE patterns under biochar treatments, though varying with site also. While the fungi copy numbers markedly varied both with sites and with biochar treatments, lower similarity and greater

  6. Optimal lineage principle for age-structured populations

    NASA Astrophysics Data System (ADS)

    Kussell, Edo

    2012-02-01

    Populations whose individuals exhibit age-dependent growth have often been studied using temporal dynamics of age distributions. In this talk, I examine the dynamics of age along lineages. We will see that the lineage point-of-view provides fundamental insights into evolutionary pressures on individuals' aging profiles. I will describe a variational principle that enables exact results for lineage statistics, in a variety of models. I will also discuss measurements on continuously dividing bacterial populations growing in microfluidics devices.

  7. Sensitivity analysis of the age-structured malaria transmission model

    NASA Astrophysics Data System (ADS)

    Addawe, Joel M.; Lope, Jose Ernie C.

    2012-09-01

    We propose an age-structured malaria transmission model and perform sensitivity analyses to determine the relative importance of model parameters to disease transmission. We subdivide the human population into two: preschool humans (below 5 years) and the rest of the human population (above 5 years). We then consider two sets of baseline parameters, one for areas of high transmission and the other for areas of low transmission. We compute the sensitivity indices of the reproductive number and the endemic equilibrium point with respect to the two sets of baseline parameters. Our simulations reveal that in areas of either high or low transmission, the reproductive number is most sensitive to the number of bites by a female mosquito on the rest of the human population. For areas of low transmission, we find that the equilibrium proportion of infectious pre-school humans is most sensitive to the number of bites by a female mosquito. For the rest of the human population it is most sensitive to the rate of acquiring temporary immunity. In areas of high transmission, the equilibrium proportion of infectious pre-school humans and the rest of the human population are both most sensitive to the birth rate of humans. This suggests that strategies that target the mosquito biting rate on pre-school humans and those that shortens the time in acquiring immunity can be successful in preventing the spread of malaria.

  8. Increased seawater temperature increases the abundance and alters the structure of natural Vibrio populations associated with the coral Pocillopora damicornis

    PubMed Central

    Tout, Jessica; Siboni, Nachshon; Messer, Lauren F.; Garren, Melissa; Stocker, Roman; Webster, Nicole S.; Ralph, Peter J.; Seymour, Justin R.

    2015-01-01

    Rising seawater temperature associated with global climate change is a significant threat to coral health and is linked to increasing coral disease and pathogen-related bleaching events. We performed heat stress experiments with the coral Pocillopora damicornis, where temperature was increased to 31°C, consistent with the 2–3°C predicted increase in summer sea surface maxima. 16S rRNA amplicon sequencing revealed a large shift in the composition of the bacterial community at 31°C, with a notable increase in Vibrio, including known coral pathogens. To investigate the dynamics of the naturally occurring Vibrio community, we performed quantitative PCR targeting (i) the whole Vibrio community and (ii) the coral pathogen Vibrio coralliilyticus. At 31°C, Vibrio abundance increased by 2–3 orders of magnitude and V. coralliilyticus abundance increased by four orders of magnitude. Using a Vibrio-specific amplicon sequencing assay, we further demonstrated that the community composition shifted dramatically as a consequence of heat stress, with significant increases in the relative abundance of known coral pathogens. Our findings provide quantitative evidence that the abundance of potential coral pathogens increases within natural communities of coral-associated microbes as a consequence of rising seawater temperature and highlight the potential negative impacts of anthropogenic climate change on coral reef ecosystems. PMID:26042096

  9. Genetic structure of the benthic amphipod Diporeia (Amphipoda: Pontoporeiidae) and its relationship to abundance in Lake Superior

    EPA Science Inventory

    The freshwater amphipod Diporeia is a crucial part of the food web in the Laurentian Great Lakes, but has faced serious declines correlated with the invasion of zebra mussels (Dreissena polymorpha), except in Lake Superior, which has seen an increase in Diporeia abundance. Specul...

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

    NASA Astrophysics Data System (ADS)

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

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

  11. [Effects of different fertilization regimes on abundance and community structure of the nirK-type denitrifying bacteria in greenhouse vegetable soils].

    PubMed

    Zeng, Xi-Bai; Wang, Ya-Nan; Wang, Yu-Zhong; Bai, Ling-Yu; Li, Lian-Fang; Duan, Ran; Su, Shi-Ming; Wu, Cui-Xia

    2014-02-01

    The community structure and abundance of nirK-type denitrifying bacteria in different soil layers (0-20 cm and 20-40 cm) under various fertilization regimes in Wuwei, Gansu Province were investigated by the combination of terminal restriction fragment length polymorphism (T-RFLP) and real-time quantitative PCR. Results showed that the nirK-type denitrifying bacteria community structure was significantly affected by fertilization regimes, especially for 70, 156 and 190 bp T-RFs that represented the dominant populations in greenhouse soil. Fertilization regimes significantly influenced the abundance of nirK gene in the 0-20 cm soil layer with the highest abundance of nirK gene copy number (2.16 x 10(7) copies x g(-1) soil) detected in the manure treatment (M), which was 2.04 and 2.02 times of that in the control (CK) and chemical fertilizer (NPK) treatments, respectively. Both the dominant population and abundance of nirK-type denitrifying bacteria in the greenhouse soil were significantly different between the 0-20 cm and 20-40 cm soil layers, and the nirK-type denitrifying bacteria community structure and abundance in the greenhouse soil were obviously different from that in the field. Soil pH, soil organic matter content and nitrate-N content had the greatest influence on the bacterial community composition. Phylogenetic analysis indicated that there were not only anaerobic nirK-type denitrifying bacteria in greenhouse soil, but also aerobic denitrifying bacteria, such as Rhizobium, Ochrobactrum, Agrobacterium. PMID:24830252

  12. Effects of bioaugmentation in para-nitrophenol-contaminated soil on the abundance and community structure of ammonia-oxidizing bacteria and archaea.

    PubMed

    Chi, Xiang-Qun; Liu, Kun; Zhou, Ning-Yi

    2015-07-01

    Pseudomonas sp. strain WBC-3 mineralizes the priority pollutant para-nitrophenol (PNP) and releases nitrite (NO2 (-)), which is probably involved in the nitrification. In this study, the rate of PNP removal in soil bioaugmented with strain WBC-3 was more accelerated with more NO2 (-) accumulation than in uninoculated soils. Strain WBC-3 survived well and remained stable throughout the entire period. Real-time polymerase chain reaction (real-time PCR) indicated a higher abundance of ammonia-oxidizing bacteria (AOB) than ammonia-oxidizing archaea (AOA), suggesting that AOB played a greater role in nitrification in the original sampled soil. Real-time PCR and multivariate analysis based on the denaturing gradient gel electrophoresis showed that PNP contamination did not significantly alter the abundance and community structure of ammonia oxidizers except for inhibiting the AOB abundance. Bioaugmentation of PNP-contaminated soil showed a significant effect on AOB populations and community structure as well as AOA populations. In addition, ammonium (NH4 (+)) variation was found to be the primary factor affecting the AOB community structure, as determined by the correlation between the community structures of ammonia oxidizers and environmental factors. It is here proposed that the balance between archaeal and bacterial ammonia oxidation could be influenced significantly by the variation in NH4 (+) levels as caused by bioaugmentation of contaminated soil by a pollutant containing nitrogen.

  13. 77 FR 27815 - Aging Management of Stainless Steel Structures and Components in Treated Borated Water

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-11

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

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

    NASA Astrophysics Data System (ADS)

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

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

  15. [Bacterial community structure and diversity in soils of different forest ages and types in Bao- tianman forest, Henan Province, China].

    PubMed

    Bai, Xiao-xu; Shi, Rong-ju; You, Ye-ming; Sheng, Hua-fang; Han, Si-qin; Zhang, Ying

    2015-08-01

    To compare the microbial compositions and diversities in soils of different forest ages and types in Baotianman forest, Henan Province, China, genomic DNA of forest soils was extracted for amplifying the 16S rRNA V4 hyper variable region by PCR and sequencing by Illumina MiSeq. The BIPES, UCHIME and QIIME were employed to analyze the soil bacterial community. It was shown that 60 phyla were identified, with Proteobacteria, Acidobacteria, and Verrucomicrobia representing the most dominant lineages and accounting for 29%, 18.5% and 10% of all sequences, respectively. At the genus level, 1209 genera were identified, the most abundant phylotypes were DA101 (6.3%), Acidobacteria-2 (5.9%), Candidatus Solibacter (2.9%) and Candidatus Nitrososphaera (2.6%). Different forest age and type soil samples had unique compositions and specific high and rare genus. Forest type and age both impacted the soil microbial community structure, and the influence of the former was stronger than the latter. The soil microbial diversity of the 80-year-old Quercus aliena forest was the lowest among all age and type forest soil samples. Soil pH, soil nitrogen and organic carbon contents were the most important factors affecting soil bacterial community structure.

  16. Community structure and abundance of ammonia-oxidizing archaea and bacteria after conversion from soybean to rice paddy in albic soils of Northeast China.

    PubMed

    Wang, Jing; Wang, Weidong; Gu, Ji-Dong

    2014-03-01

    Community composition of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in the albic soil grown with soybean and rice for different years was investigated by construction of clone libraries, denaturing gradient gel electrophoresis (DGGE), and quantitative polymerase chain reaction (q-PCR) by PCR amplification of the ammonia monooxygenase subunit A (amoA) gene. Soil samples were collected at two layers (0-5 and 20-25 cm) from a soybean field and four rice paddy fields with 1, 5, 9, and 17 years of continuous rice cultivation. Both the community structures and abundances of AOA and AOB showed detectable changes after conversion from soybean to rice paddy judged by clone library, DGGE, and q-PCR analyses. In general, the archaeal amoA gene abundance increased after conversion to rice cultivation, while bacterial amoA gene abundance decreased. The abundances of both AOA and AOB were higher in the surface layer than the bottom one in the soybean field, but a reverse trend was observed for AOB in all paddy samples regardless of the duration of paddy cultivation. Phylogenetic analysis identified nine subclusters of AOA and seven subclusters of AOB. Community composition of both AOA and AOB was correlated with available ammonium and increased pH value caused by flooding in multiple variance analysis. Community shift of AOB was also observed in different paddy fields, but the two layers did not show any detectable changes in DGGE analysis. Conversion from soybean to rice cultivation changed the community structure and abundance of AOA and AOB in albic agricultural soil, which requires that necessary cultivation practice be followed to manage the N utilization more effectively. PMID:24092004

  17. Changes in abundance and community structure of nematodes from the abyssal polymetallic nodule field, Tropical Northeast Pacific

    NASA Astrophysics Data System (ADS)

    Miljutin, Dmitry; Miljutina, Maria; Messié, Monique

    2015-12-01

    Deep-sea fields of polymetallic nodules in the Clarion-Clipperton Zone (CCFZ, tropical NE Pacific) are currently being investigated to assess their potential for commercial mining. During such mining, benthic communities will be inevitably disturbed or destroyed. Therefore, assessments of their standing stock and composition may be helpful for the future evaluation of possible impacts of commercial nodule exploitation. Analysis of nematode communities (at genus level) inhabiting the French license area of the CCFZ were studied based on data from the cruises NODINAUT (2004) and BIONOD (2012). The total nematode density was ca. 1.5-fold higher in 2012 as compared with 2004. This reflected a 2-2.5 times higher density of non-selective deposit-feeders (i.e. possessing a small buccal cavity without armature) in 2012 compared with 2004, whereas no significant differences between sampling periods were observed in the density of the other feeding groups. Consequently, whilst the list of the most abundant genera was identical, their relative abundances changed significantly. The relative abundance of the genus Thalassomonhystera was two times greater in 2012 than in 2004, whereas the relative abundances of the genera Acantholaimus and Theristus were significantly lower in 2012 (10% and 4%, respectively) than in 2004 (28% and 9%). Nematode diversity (including values of diversity indices and total number of recorded genera) was significantly lower in 2012 in comparison with 2004. Although our data do not take into account seasonal and shorter temporal scales of variability in nematode assemblages, we report here that a certain fraction of variations observed between the two sampling periods could be associated with differences in primary production. Future studies should aim to better characterise temporal variability in nematode communities of the CCFZ at seasonal and interannual scales.

  18. Influence of surface salinity gradient on dinoflagellate cyst community structure, abundance and morphology in the Baltic Sea, Kattegat and Skagerrak

    NASA Astrophysics Data System (ADS)

    Sildever, Sirje; Andersen, Thorbjørn Joest; Ribeiro, Sofia; Ellegaard, Marianne

    2015-03-01

    Changes in dinoflagellate cyst forming species composition, abundance and morphology along the surface salinity gradient in the Baltic Sea, Kattegat and Skagerrak were investigated and compared with detailed surface salinity data. A strong positive correlation was found between species diversity and surface salinity (R2 = 0.94; n = 7) in the Baltic Sea-Kattegat-Skagerrak system. The most pronounced decrease in dinoflagellate cyst diversity occurred between Kattegat and the Arkona basin, where the surface salinity also steeply declined. Overall, the total cyst abundance decreased along the salinity gradient. However, in the Gotland and particularly in the Northern Central basin cyst concentrations were elevated compared to the surrounding basins and the cyst community was dominated by heterotrophic cyst-producing dinoflagellate species. Possible factors behind this observation are discussed, with increased nutrient supply as the most likely primary cause. In addition, surface salinity was also confirmed to influence process length development of Operculodinium centrocarpum (R2 = 0.86; n = 145), which was the most abundant species in this study.

  19. Semantics, Phrase Structure and Age as Variables in Sentence Recall.

    ERIC Educational Resources Information Center

    Van Every, Harolyn; Rosenberg, Sheldon

    Forty first-grade and 40 seventh-grade children were assigned at random to four groups of 20 each (two at each age level) and were administered four study-test trials involving oral presentation and oral recall of a list of four sentences of the form article-adjective-noun-verb-adverb. Half of the subjects at each level of age were given…

  20. Age of onset of schizophrenia: perspectives from structural neuroimaging studies.

    PubMed

    Gogtay, Nitin; Vyas, Nora S; Testa, Renee; Wood, Stephen J; Pantelis, Christos

    2011-05-01

    Many of the major neuropsychiatric illnesses, including schizophrenia, have a typical age of onset in late adolescence. Late adolescence may reflect a critical period in brain development making it particularly vulnerable for the onset of psychopathology. Neuroimaging studies that focus on this age range may provide unique insights into the onset and course of psychosis. In this review, we examine the evidence from 2 unique longitudinal cohorts that span the ages from early childhood through young adulthood; a study of childhood-onset schizophrenia where patients and siblings are followed from ages 6 through to their early twenties, and an ultra-high risk study where subjects (mean age of 19 years) are studied before and after the onset of psychosis. From the available evidence, we make an argument that subtle, regionally specific, and genetically influenced alterations during developmental age windows influence the course of psychosis and the resultant brain phenotype. The importance of examining trajectories of development and the need for future combined approaches, using multimodal imaging together with molecular studies is discussed. PMID:21505117

  1. Structural evolution in the aging process of supercooled colloidal liquids.

    PubMed

    Kawasaki, Takeshi; Tanaka, Hajime

    2014-06-01

    When a liquid is rapidly quenched to a temperature below the glass-transition point, it is driven out of equilibrium; it then slowly relaxes to a (quasi)equilibrium state. This slow relaxation process is called aging. By definition, any glasses are inevitably in the process of aging and actually slowly evolving with time. Thus the study of aging phenomena is of fundamental importance for understanding not only the nonequilibrium nature of the glass transition, but also the stability of glassy materials. Here we consider aging after a rather shallow quench, for which a system is still able to reach (metastable) equilibrium. By using polydisperse colloidal liquids as a model, we show the validity of dynamical scaling that there is only one relevant length scale not only for a quasiequilibrium supercooled state but also for a nonequilibrium process of aging, which is reminiscent of dynamical critical phenomena. Our finding indicates that the aging toward (metastable) equilibrium may be regarded as the growth process of critical-like fluctuations of static order associated with low-free-energy configurations, further suggesting that this ordering is the origin of cooperative slow dynamics in the systems studied. The generality of this statement for other glass-forming systems remains for a future study. PMID:25019784

  2. Age of Onset of Schizophrenia: Perspectives From Structural Neuroimaging Studies

    PubMed Central

    Gogtay, Nitin; Vyas, Nora S.; Testa, Renee; Wood, Stephen J.; Pantelis, Christos

    2011-01-01

    Many of the major neuropsychiatric illnesses, including schizophrenia, have a typical age of onset in late adolescence. Late adolescence may reflect a critical period in brain development making it particularly vulnerable for the onset of psychopathology. Neuroimaging studies that focus on this age range may provide unique insights into the onset and course of psychosis. In this review, we examine the evidence from 2 unique longitudinal cohorts that span the ages from early childhood through young adulthood; a study of childhood-onset schizophrenia where patients and siblings are followed from ages 6 through to their early twenties, and an ultra-high risk study where subjects (mean age of 19 years) are studied before and after the onset of psychosis. From the available evidence, we make an argument that subtle, regionally specific, and genetically influenced alterations during developmental age windows influence the course of psychosis and the resultant brain phenotype. The importance of examining trajectories of development and the need for future combined approaches, using multimodal imaging together with molecular studies is discussed. PMID:21505117

  3. Structural evolution in the aging process of supercooled colloidal liquids

    NASA Astrophysics Data System (ADS)

    Kawasaki, Takeshi; Tanaka, Hajime

    2014-06-01

    When a liquid is rapidly quenched to a temperature below the glass-transition point, it is driven out of equilibrium; it then slowly relaxes to a (quasi)equilibrium state. This slow relaxation process is called aging. By definition, any glasses are inevitably in the process of aging and actually slowly evolving with time. Thus the study of aging phenomena is of fundamental importance for understanding not only the nonequilibrium nature of the glass transition, but also the stability of glassy materials. Here we consider aging after a rather shallow quench, for which a system is still able to reach (metastable) equilibrium. By using polydisperse colloidal liquids as a model, we show the validity of dynamical scaling that there is only one relevant length scale not only for a quasiequilibrium supercooled state but also for a nonequilibrium process of aging, which is reminiscent of dynamical critical phenomena. Our finding indicates that the aging toward (metastable) equilibrium may be regarded as the growth process of critical-like fluctuations of static order associated with low-free-energy configurations, further suggesting that this ordering is the origin of cooperative slow dynamics in the systems studied. The generality of this statement for other glass-forming systems remains for a future study.

  4. Shifts in the abundance and community structure of soil ammonia oxidizers in a wet sclerophyll forest under long-term prescribed burning.

    PubMed

    Long, Xi-En; Chen, Chengrong; Xu, Zhihong; He, Ji-Zheng

    2014-02-01

    Fire shapes global biome distribution and promotes the terrestrial biogeochemical cycles. Ammonia-oxidizing bacteria (AOB) and archaea (AOA) play a vital role in the biogeochemical cycling of nitrogen (N). However, behaviors of AOB and AOA under long-term prescribed burning remain unclear. This study was to examine how fire affected the abundances and communities of soil AOB and AOA. A long-term repeated forest fire experiment with three burning treatments (never burnt, B0; biennially burnt, B2; and quadrennially burnt, B4) was used in this study. The abundances and community structure of soil AOB and AOA were determined using quantitative PCR, restriction fragment length polymorphism and clone library. More frequent fires (B2) increased the abundance of bacterium amoA gene, but tended to decrease archaeal amoA genes. Fire also modified the composition of AOA and AOB communities. Canonical correspondence analysis showed soil pH and dissolved organic C (DOC) strongly affected AOB genotypes, while nitrate-N and DOC shaped the AOA distribution. The increased abundance of bacterium amoA gene by fires may imply an important role of AOB in nitrification in fire-affected soils. The fire-induced shift in the community composition of AOB and AOA demonstrates that fire can disturb nutrient cycles.

  5. Effects of Fragment and Vegetation Structure on the Population Abundance of Ateles hybridus, Alouatta seniculus and Cebus albifrons in Magdalena Valley, Colombia.

    PubMed

    Marsh, Christopher; Link, Andres; King-Bailey, Gillian; Donati, Giuseppe

    2016-01-01

    Many primate species currently subsist in fragmented and anthropogenically disturbed habitats. Different threats arise depending on the species' life history strategy, dietary requirements and habitat preference. Additionally, anthropogenic disturbance is far from uniform and may affect individual forest fragments in a single landscape in differing ways. We studied the effects of fragmentation on three species of diurnal primate, Cebus albifrons, Alouatta seniculus and Ateles hybridus, in Magdalena Valley, Colombia. We tested the assumption that generalist species are more resilient than specialist species to habitat degradation by examining the fragments' vegetation and spatial structure and how these affected primate presence and abundance patterns. We found C. albifrons, a generalist, to be the most abundant species in 9 of 10 forest fragments, regardless of the level of habitat disturbance. A. hybridus, a large-bodied primate with a specialist diet, was either absent or low in abundance in fragments that had experienced recent disturbances and was found only in higher-quality fragments, regardless of the fragment size. A. seniculus, a species considered to have a highly flexible diet and the ability to survive in degraded habitat, was found in intermediate abundances between those of Cebus spp. and Ateles spp., and was more frequently found in high-quality fragments. PMID:27093602

  6. Camera Traps on Wildlife Crossing Structures as a Tool in Gray Wolf (Canis lupus) Management - Five-Years Monitoring of Wolf Abundance Trends in Croatia.

    PubMed

    Šver, Lidija; Bielen, Ana; Križan, Josip; Gužvica, Goran

    2016-01-01

    The conservation of gray wolf (Canis lupus) and its coexistence with humans presents a challenge and requires continuous monitoring and management efforts. One of the non-invasive methods that produces high-quality wolf monitoring datasets is camera trapping. We present a novel monitoring approach where camera traps are positioned on wildlife crossing structures that channel the animals, thereby increasing trapping success and increasing the cost-efficiency of the method. In this way we have followed abundance trends of five wolf packs whose home ranges are intersected by a motorway which spans throughout the wolf distribution range in Croatia. During the five-year monitoring of six green bridges we have recorded 28 250 camera-events, 132 with wolves. Four viaducts were monitored for two years, recording 4914 camera-events, 185 with wolves. We have detected a negative abundance trend of the monitored Croatian wolf packs since 2011, especially severe in the northern part of the study area. Further, we have pinpointed the legal cull as probable major negative influence on the wolf pack abundance trends (linear regression, r2 > 0.75, P < 0.05). Using the same approach we did not find evidence for a negative impact of wolves on the prey populations, both wild ungulates and livestock. We encourage strict protection of wolf in Croatia until there is more data proving population stability. In conclusion, quantitative methods, such as the one presented here, should be used as much as possible when assessing wolf abundance trends. PMID:27327498

  7. Camera Traps on Wildlife Crossing Structures as a Tool in Gray Wolf (Canis lupus) Management - Five-Years Monitoring of Wolf Abundance Trends in Croatia

    PubMed Central

    Križan, Josip; Gužvica, Goran

    2016-01-01

    The conservation of gray wolf (Canis lupus) and its coexistence with humans presents a challenge and requires continuous monitoring and management efforts. One of the non-invasive methods that produces high-quality wolf monitoring datasets is camera trapping. We present a novel monitoring approach where camera traps are positioned on wildlife crossing structures that channel the animals, thereby increasing trapping success and increasing the cost-efficiency of the method. In this way we have followed abundance trends of five wolf packs whose home ranges are intersected by a motorway which spans throughout the wolf distribution range in Croatia. During the five-year monitoring of six green bridges we have recorded 28 250 camera-events, 132 with wolves. Four viaducts were monitored for two years, recording 4914 camera-events, 185 with wolves. We have detected a negative abundance trend of the monitored Croatian wolf packs since 2011, especially severe in the northern part of the study area. Further, we have pinpointed the legal cull as probable major negative influence on the wolf pack abundance trends (linear regression, r2 > 0.75, P < 0.05). Using the same approach we did not find evidence for a negative impact of wolves on the prey populations, both wild ungulates and livestock. We encourage strict protection of wolf in Croatia until there is more data proving population stability. In conclusion, quantitative methods, such as the one presented here, should be used as much as possible when assessing wolf abundance trends. PMID:27327498

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

    USGS Publications Warehouse

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

    2008-01-01

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

  9. [Structure of the articular cartilage in the middle aged].

    PubMed

    Kop'eva, T N; Mul'diiarov, P Ia; Bel'skaia, O B; Pastel', V B

    1983-10-01

    In persons 17-83 years of age having no articular disorders 39 samples of the patellar articular cartilage, the articulated surface and the femoral head have been studied histochemically, histometrically and electron microscopically. Age involution of the articular cartilage is revealed after 40 years of age as a progressive decrease in chondrocytes density in the superficial and (to a less degree) in the intermediate zones. This is accompanied with a decreasing number of 3- and 4-cellular lacunae and with an increasing number of unicellular and hollow lacunae. In some chondrocytes certain distrophic and necrotic changes are revealed. In the articular matrix the zone with the minimal content of glycosaminoglycans becomes thicker and keratansulfate content in the territorial matrix of the cartilage deep zone grows large.

  10. On the dynamics of the age structure, dependency, and consumption

    PubMed Central

    Hock, Heinrich

    2013-01-01

    We examine the effects of population aging due to declining fertility and rising elderly life expectancy on consumption possibilities in the presence of intergenerational transfers. Our analysis is based on a highly tractable continuous-time overlapping generations model in which the population is divided into three groups (youth dependents, workers, and elderly dependents) and lifecourse transitions take place in a probabilistic fashion. We show that the consumption-maximizing response to greater longevity in highly developed countries is an increase in fertility. However, with larger transfer payments, the actual fertility response will likely be the opposite, leading to further population aging. PMID:24353374

  11. The Role of Temporal Abundance Structure and Habitat Preferences in the Survival of Conodonts during the Mid-Early Silurian Ireviken Mass Extinction Event

    PubMed Central

    Spiridonov, Andrej; Brazauskas, Antanas; Radzevičius, Sigitas

    2015-01-01

    The Ireviken event was one of the most intense extinction episodes that occurred during the mid-Paleozoic era. It had a strong global effect on a range of clades, with conodonts, graptolites and chitinozoans affected most. Using geophysical proxies and conodont species parameters of their temporal abundance structure we investigate how they affected the selectivity of conodont species survival during this calamity. After performing bivariate logistic analyses on 34 species of conodonts, we find three variables that were statistically significantly associated with their odds of survival. These namely include spectral exponents that describe degrees of autocorrelation in a time series, the skewness of species abundance distribution, and average environmental preferences, which are mostly determined by ancient water depths at sampling sites. Model selection of multivariate logistic models found the best model includes species local abundance skewness and substrate preference. A similar pattern is revealed through the regression tree analysis. The apparent extinction selectivity points to a possible causes of environmental deterioration during the Ireviken event. The significant positive relationship between extinction risk and preferential existence in deeper environments suggests the open ocean causal mechanisms of biotic stress that occurred during the Ireviken event. Marine regressions, which were previously suggested as a causal factor in this extinction episode, on theoretical grounds should have had higher impact on species living in near-shore environments, through the processes of habitat loss which are associated with decreases of shelfal areas. In addition, the significant positive correlations found between skewness of abundance distributions and spectral exponent values and the probability of species survival suggest that community and ecosystem processes (which controlled species abundance fluctuation patterns) were significantly related to selectivity

  12. The role of temporal abundance structure and habitat preferences in the survival of conodonts during the mid-early Silurian Ireviken mass extinction event.

    PubMed

    Spiridonov, Andrej; Brazauskas, Antanas; Radzevičius, Sigitas

    2015-01-01

    The Ireviken event was one of the most intense extinction episodes that occurred during the mid-Paleozoic era. It had a strong global effect on a range of clades, with conodonts, graptolites and chitinozoans affected most. Using geophysical proxies and conodont species parameters of their temporal abundance structure we investigate how they affected the selectivity of conodont species survival during this calamity. After performing bivariate logistic analyses on 34 species of conodonts, we find three variables that were statistically significantly associated with their odds of survival. These namely include spectral exponents that describe degrees of autocorrelation in a time series, the skewness of species abundance distribution, and average environmental preferences, which are mostly determined by ancient water depths at sampling sites. Model selection of multivariate logistic models found the best model includes species local abundance skewness and substrate preference. A similar pattern is revealed through the regression tree analysis. The apparent extinction selectivity points to a possible causes of environmental deterioration during the Ireviken event. The significant positive relationship between extinction risk and preferential existence in deeper environments suggests the open ocean causal mechanisms of biotic stress that occurred during the Ireviken event. Marine regressions, which were previously suggested as a causal factor in this extinction episode, on theoretical grounds should have had higher impact on species living in near-shore environments, through the processes of habitat loss which are associated with decreases of shelfal areas. In addition, the significant positive correlations found between skewness of abundance distributions and spectral exponent values and the probability of species survival suggest that community and ecosystem processes (which controlled species abundance fluctuation patterns) were significantly related to selectivity

  13. Arbuscular Mycorrhizal Fungi Community Structure, Abundance and Species Richness Changes in Soil by Different Levels of Heavy Metal and Metalloid Concentration

    PubMed Central

    Krishnamoorthy, Ramasamy; Kim, Chang-Gi; Subramanian, Parthiban; Kim, Ki-Yoon; Selvakumar, Gopal; Sa, Tong-Min

    2015-01-01

    Arbuscular Mycorrhizal Fungi (AMF) play major roles in ecosystem functioning such as carbon sequestration, nutrient cycling, and plant growth promotion. It is important to know how this ecologically important soil microbial player is affected by soil abiotic factors particularly heavy metal and metalloid (HMM). The objective of this study was to understand the impact of soil HMM concentration on AMF abundance and community structure in the contaminated sites of South Korea. Soil samples were collected from the vicinity of an abandoned smelter and the samples were subjected to three complementary methods such as spore morphology, terminal restriction fragment length polymorphism (T-RFLP) and denaturing gradient gel electrophoresis (DGGE) for diversity analysis. Spore density was found to be significantly higher in highly contaminated soil compared to less contaminated soil. Spore morphological study revealed that Glomeraceae family was more abundant followed by Acaulosporaceae and Gigasporaceae in the vicinity of the smelter. T-RFLP and DGGE analysis confirmed the dominance of Funneliformis mosseae and Rhizophagus intraradices in all the study sites. Claroideoglomus claroideum, Funneliformis caledonium, Rhizophagus clarus and Funneliformis constrictum were found to be sensitive to high concentration of soil HMM. Richness and diversity of Glomeraceae family increased with significant increase in soil arsenic, cadmium and zinc concentrations. Our results revealed that the soil HMM has a vital impact on AMF community structure, especially with Glomeraceae family abundance, richness and diversity. PMID:26035444

  14. Arbuscular mycorrhizal fungi community structure, abundance and species richness changes in soil by different levels of heavy metal and metalloid concentration.

    PubMed

    Krishnamoorthy, Ramasamy; Kim, Chang-Gi; Subramanian, Parthiban; Kim, Ki-Yoon; Selvakumar, Gopal; Sa, Tong-Min

    2015-01-01

    Arbuscular Mycorrhizal Fungi (AMF) play major roles in ecosystem functioning such as carbon sequestration, nutrient cycling, and plant growth promotion. It is important to know how this ecologically important soil microbial player is affected by soil abiotic factors particularly heavy metal and metalloid (HMM). The objective of this study was to understand the impact of soil HMM concentration on AMF abundance and community structure in the contaminated sites of South Korea. Soil samples were collected from the vicinity of an abandoned smelter and the samples were subjected to three complementary methods such as spore morphology, terminal restriction fragment length polymorphism (T-RFLP) and denaturing gradient gel electrophoresis (DGGE) for diversity analysis. Spore density was found to be significantly higher in highly contaminated soil compared to less contaminated soil. Spore morphological study revealed that Glomeraceae family was more abundant followed by Acaulosporaceae and Gigasporaceae in the vicinity of the smelter. T-RFLP and DGGE analysis confirmed the dominance of Funneliformis mosseae and Rhizophagus intraradices in all the study sites. Claroideoglomus claroideum, Funneliformis caledonium, Rhizophagus clarus and Funneliformis constrictum were found to be sensitive to high concentration of soil HMM. Richness and diversity of Glomeraceae family increased with significant increase in soil arsenic, cadmium and zinc concentrations. Our results revealed that the soil HMM has a vital impact on AMF community structure, especially with Glomeraceae family abundance, richness and diversity. PMID:26035444

  15. The effect of human settlement on the abundance and community structure of ammonia oxidizers in tropical stream sediments

    PubMed Central

    Reis, Mariana P.; Ávila, Marcelo P.; Keijzer, Rosalinde M.; Barbosa, Francisco A. R.; Chartone-Souza, Edmar; Nascimento, Andréa M. A.; Laanbroek, Hendrikus J.

    2015-01-01

    Ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) are a diverse and functionally important group in the nitrogen cycle. Nevertheless, AOA and AOB communities driving this process remain uncharacterized in tropical freshwater sediment. Here, the effect of human settlement on the AOA and AOB diversity and abundance have been assessed by phylogenetic and quantitative PCR analyses, using archaeal and bacterial amoA and 16S rRNA genes. Overall, each environment contained specific clades of amoA and 16S rRNA genes sequences, suggesting that selective pressures lead to AOA and AOB inhabiting distinct ecological niches. Human settlement activities, as derived from increased metal and mineral nitrogen contents, appear to cause a response among the AOB community, with Nitrosomonas taking advantage over Nitrosospira in impacted environments. We also observed a dominance of AOB over AOA in mining-impacted sediments, suggesting that AOB might be the primary drivers of ammonia oxidation in these sediments. In addition, ammonia concentrations demonstrated to be the driver for the abundance of AOA, with an inversely proportional correlation between them. Our findings also revealed the presence of novel ecotypes of Thaumarchaeota, such as those related to the obligate acidophilic Nitrosotalea devanaterra at ammonia-rich places of circumneutral pH. These data add significant new information regarding AOA and AOB from tropical freshwater sediments, albeit future studies would be required to provide additional insights into the niche differentiation among these microorganisms. PMID:26379659

  16. The Group Abundance Fraction: A statistically robust measure of particle composition and of spatial structure in images

    NASA Astrophysics Data System (ADS)

    Roelof, Edmond C.

    2015-01-01

    When two processes (A and B) are measured by counting instruments, we wish to present the results as an "abundance" along with an associated uncertainty. When the number of individual counts of either component is low, the usual ratio (A/B) is statistically ill-defined because there is a finite probability of zero counts in the denominator. However, the "Group Abundance Fraction" (F), e.g., A/(A+B), is a statistically robust parameter (under the condition that there must be at least one total count between A and B in order to constitute a measurement). We rigorously derive expectation values (over a conditional Poisson statistical ensemble) for and its standard deviation σF that are valid for all values of total counts greater than one. We then derive useful estimators for these ensemble expectation values in terms of simple algebraic functions of the actual observed accumulated counts. We also incorporate the practical effects of instrument response functions and background rates. The results are not restricted to particle species composition (or spectra), but are also applicable when A and B represent counts in adjacent "pixels" of spatial images formed by the particles.

  17. 15 CFR 50.5 - Fee structure for age search and citizenship information.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 15 Commerce and Foreign Trade 1 2011-01-01 2011-01-01 false Fee structure for age search and citizenship information. 50.5 Section 50.5 Commerce and Foreign Trade Regulations Relating to Commerce and... THE CENSUS § 50.5 Fee structure for age search and citizenship information. Type of service...

  18. 15 CFR 50.5 - Fee structure for age search and citizenship information.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 15 Commerce and Foreign Trade 1 2014-01-01 2014-01-01 false Fee structure for age search and citizenship information. 50.5 Section 50.5 Commerce and Foreign Trade Regulations Relating to Commerce and... THE CENSUS § 50.5 Fee structure for age search and citizenship information. Type of service...

  19. 15 CFR 50.5 - Fee structure for age search and citizenship information.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 15 Commerce and Foreign Trade 1 2012-01-01 2012-01-01 false Fee structure for age search and citizenship information. 50.5 Section 50.5 Commerce and Foreign Trade Regulations Relating to Commerce and... THE CENSUS § 50.5 Fee structure for age search and citizenship information. Type of service...

  20. 15 CFR 50.5 - Fee structure for age search and citizenship information.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 15 Commerce and Foreign Trade 1 2010-01-01 2010-01-01 false Fee structure for age search and citizenship information. 50.5 Section 50.5 Commerce and Foreign Trade Regulations Relating to Commerce and... THE CENSUS § 50.5 Fee structure for age search and citizenship information. Type of service...

  1. 15 CFR 50.5 - Fee structure for age search and citizenship information.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 15 Commerce and Foreign Trade 1 2013-01-01 2013-01-01 false Fee structure for age search and citizenship information. 50.5 Section 50.5 Commerce and Foreign Trade Regulations Relating to Commerce and... THE CENSUS § 50.5 Fee structure for age search and citizenship information. Type of service...

  2. Structural and functional imaging correlates for age-related changes in the brain.

    PubMed

    Tumeh, Paul C; Alavi, Abass; Houseni, Mohamed; Greenfield, Antje; Chryssikos, Timothy; Newberg, Andrew; Torigian, Drew A; Moonis, Gul

    2007-03-01

    In recent years, investigators have made significant progress in documenting brain structure and function as it relates to aging by using positron emission tomography, conventional magnetic resonance (MR) imaging, advanced MR techniques, and functional MR imaging. This review summarizes the latest advances in understanding physiologic maturation and aging as detected by these neuroimaging modalities. We also present our experience with MR volumetric and positron emission tomography analysis in separate cohorts of healthy subjects in the pediatric and adult age groups respectively. Our results are consistent with previous studies and include the following: total brain volume was found to increase with age (up to 20 years of age). Whole brain metabolism and frontal lobe metabolism both decrease significantly with age (38% and 42%, respectively), whereas cerebellar metabolism does not show a significant decline with age. Defining normal alterations in brain function and structure allows early detection of disorders such as Alzheimer's and Parkinson's diseases, which are commonly associated with normal aging. PMID:17289456

  3. Nanoscale Structure, Dynamics, and Aging Behavior of Metallic Glass Thin Films.

    PubMed

    Burgess, J A J; Holt, C M B; Luber, E J; Fortin, D C; Popowich, G; Zahiri, B; Concepcion, P; Mitlin, D; Freeman, M R

    2016-01-01

    Scanning tunnelling microscopy observations resolve the structure and dynamics of metallic glass Cu100-xHfx films and demonstrate scanning tunnelling microscopy control of aging at a metallic glass surface. Surface clusters exhibit heterogeneous hopping dynamics. Low Hf concentration films feature an aged surface of larger, slower clusters. Argon ion-sputtering destroys the aged configuration, yielding a surface in constant fluctuation. Scanning tunnelling microscopy can locally restore the relaxed state, allowing for nanoscale lithographic definition of aged sections. PMID:27498698

  4. Nanoscale Structure, Dynamics, and Aging Behavior of Metallic Glass Thin Films

    PubMed Central

    Burgess, J. A. J.; Holt, C. M. B.; Luber, E. J.; Fortin, D. C.; Popowich, G.; Zahiri, B.; Concepcion, P.; Mitlin, D.; Freeman, M. R.

    2016-01-01

    Scanning tunnelling microscopy observations resolve the structure and dynamics of metallic glass Cu100−xHfx films and demonstrate scanning tunnelling microscopy control of aging at a metallic glass surface. Surface clusters exhibit heterogeneous hopping dynamics. Low Hf concentration films feature an aged surface of larger, slower clusters. Argon ion-sputtering destroys the aged configuration, yielding a surface in constant fluctuation. Scanning tunnelling microscopy can locally restore the relaxed state, allowing for nanoscale lithographic definition of aged sections. PMID:27498698

  5. Nanoscale Structure, Dynamics, and Aging Behavior of Metallic Glass Thin Films

    NASA Astrophysics Data System (ADS)

    Burgess, J. A. J.; Holt, C. M. B.; Luber, E. J.; Fortin, D. C.; Popowich, G.; Zahiri, B.; Concepcion, P.; Mitlin, D.; Freeman, M. R.

    2016-08-01

    Scanning tunnelling microscopy observations resolve the structure and dynamics of metallic glass Cu100-xHfx films and demonstrate scanning tunnelling microscopy control of aging at a metallic glass surface. Surface clusters exhibit heterogeneous hopping dynamics. Low Hf concentration films feature an aged surface of larger, slower clusters. Argon ion-sputtering destroys the aged configuration, yielding a surface in constant fluctuation. Scanning tunnelling microscopy can locally restore the relaxed state, allowing for nanoscale lithographic definition of aged sections.

  6. A geostatistical analysis of small-scale spatial variability in bacterial abundance and community structure in salt marsh creek bank sediments

    NASA Technical Reports Server (NTRS)

    Franklin, Rima B.; Blum, Linda K.; McComb, Alison C.; Mills, Aaron L.

    2002-01-01

    Small-scale variations in bacterial abundance and community structure were examined in salt marsh sediments from Virginia's eastern shore. Samples were collected at 5 cm intervals (horizontally) along a 50 cm elevation gradient, over a 215 cm horizontal transect. For each sample, bacterial abundance was determined using acridine orange direct counts and community structure was analyzed using randomly amplified polymorphic DNA fingerprinting of whole-community DNA extracts. A geostatistical analysis was used to determine the degree of spatial autocorrelation among the samples, for each variable and each direction (horizontal and vertical). The proportion of variance in bacterial abundance that could be accounted for by the spatial model was quite high (vertical: 60%, horizontal: 73%); significant autocorrelation was found among samples separated by 25 cm in the vertical direction and up to 115 cm horizontally. In contrast, most of the variability in community structure was not accounted for by simply considering the spatial separation of samples (vertical: 11%, horizontal: 22%), and must reflect variability from other parameters (e.g., variation at other spatial scales, experimental error, or environmental heterogeneity). Microbial community patch size based upon overall similarity in community structure varied between 17 cm (vertical) and 35 cm (horizontal). Overall, variability due to horizontal position (distance from the creek bank) was much smaller than that due to vertical position (elevation) for both community properties assayed. This suggests that processes more correlated with elevation (e.g., drainage and redox potential) vary at a smaller scale (therefore producing smaller patch sizes) than processes controlled by distance from the creek bank. c2002 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.

  7. Effects of soil tillage and management of crop residues on soil properties: abundance, biomass and diversity of earthworms, soil structure and nutrient evolutions

    NASA Astrophysics Data System (ADS)

    lemtiri, Aboulkacem

    2013-04-01

    The living soil is represented by soil biota that interacts with aboveground biota and with the abiotic environment, soil structure, soil reaction, organic matter, nutrient contents, aso. Maintenance of soil organic matter through integrated soil fertility management is an important issue to conciliate soil quality and agricultural productivity. Earthworms are key actors in soil structure formation through the production of casts and the incorporation of soil organic matter in the soil. Research is still needed about the interactive effects of various tillage and crop residue management practices on earthworm populations and physical and chemical properties of soil. To investigate the impacts of two tillage management systems and two cropping systems on earthworm populations, soil structure evolution and nutrient dynamics, we carried out a three years study in an experimental field. The aims of this experimentation, were to assess the effects of the tillage systems (ploughing versus reduced tillage) and the availability of crop residues (export versus no export) on (i) the abundance, biomass and diversity of earthworms, on the soil structure and on the temporal variation of water extractable nutrients and organic carbon. The first results show that tillage management did significantly affect earthworm abundance and biomass. However, crop residue management did not affect abundance, biomass and diversity of earthworms. Regarding soil physical properties, the tillage affected the compaction profiles within the top 30cm. The analysis of nutrient and organic carbon dynamics show divergent trends (decrease of calcium and magnesium, increase of hot water extractable carbon and phosphorus…) but no clear effect of the studied factors could be identified. The question of the initial soil variability raised as a crucial point in the discussion.

  8. Abundance and Temperature Dependency of Protein-Protein Interaction Revealed by Interface Structure Analysis and Stability Evolution.

    PubMed

    He, Yi-Ming; Ma, Bin-Guang

    2016-01-01

    Protein complexes are major forms of protein-protein interactions and implement essential biological functions. The subunit interface in a protein complex is related to its thermostability. Though the roles of interface properties in thermal adaptation have been investigated for protein complexes, the relationship between the interface size and the expression level of the subunits remains unknown. In the present work, we studied this relationship and found a positive correlation in thermophiles rather than mesophiles. Moreover, we found that the protein interaction strength in complexes is not only temperature-dependent but also abundance-dependent. The underlying mechanism for the observed correlation was explored by simulating the evolution of protein interface stability, which highlights the avoidance of misinteraction. Our findings make more complete the picture of the mechanisms for protein complex thermal adaptation and provide new insights into the principles of protein-protein interactions. PMID:27220911

  9. Abundance and Temperature Dependency of Protein-Protein Interaction Revealed by Interface Structure Analysis and Stability Evolution

    NASA Astrophysics Data System (ADS)

    He, Yi-Ming; Ma, Bin-Guang

    2016-05-01

    Protein complexes are major forms of protein-protein interactions and implement essential biological functions. The subunit interface in a protein complex is related to its thermostability. Though the roles of interface properties in thermal adaptation have been investigated for protein complexes, the relationship between the interface size and the expression level of the subunits remains unknown. In the present work, we studied this relationship and found a positive correlation in thermophiles rather than mesophiles. Moreover, we found that the protein interaction strength in complexes is not only temperature-dependent but also abundance-dependent. The underlying mechanism for the observed correlation was explored by simulating the evolution of protein interface stability, which highlights the avoidance of misinteraction. Our findings make more complete the picture of the mechanisms for protein complex thermal adaptation and provide new insights into the principles of protein-protein interactions.

  10. Age-class structure and variability of two populations of the bluemask darter etheostoma (Doration) sp.

    USGS Publications Warehouse

    Simmons, J.W.; Layzer, J.B.; Smith, D.D.

    2008-01-01

    The bluemask darter Etheostoma (Doration) sp. is an endangered fish endemic to the upper Caney Fork system in the Cumberland River drainage in central Tennessee. Darters (Etheostoma spp.) are typically short-lived and exhibit rapid growth that quickly decreases with age. Consequently, estimating age of darters from length-frequency distributions can be difficult and subjective. We used a nonparametric kernel density estimator to reduce subjectivity in estimating ages of bluemask darters. Data were collected from a total of 2926 bluemask darters from the Collins River throughout three growing seasons. Additionally, data were collected from 842 bluemask darters from the Rocky River during one growing season. Analysis of length-frequencies indicated the presence of four age classes in both rivers. In each river, the majority of the population was comprised of fish 0.05). In both rivers, females were more abundant than males.

  11. Radiostratigraphy and age structure of the Greenland Ice Sheet

    PubMed Central

    MacGregor, Joseph A; Fahnestock, Mark A; Catania, Ginny A; Paden, John D; Prasad Gogineni, S; Young, S Keith; Rybarski, Susan C; Mabrey, Alexandria N; Wagman, Benjamin M; Morlighem, Mathieu

    2015-01-01

    Several decades of ice-penetrating radar surveys of the Greenland and Antarctic ice sheets have observed numerous widespread internal reflections. Analysis of this radiostratigraphy has produced valuable insights into ice sheet dynamics and motivates additional mapping of these reflections. Here we present a comprehensive deep radiostratigraphy of the Greenland Ice Sheet from airborne deep ice-penetrating radar data collected over Greenland by The University of Kansas between 1993 and 2013. To map this radiostratigraphy efficiently, we developed new techniques for predicting reflection slope from the phase recorded by coherent radars. When integrated along track, these slope fields predict the radiostratigraphy and simplify semiautomatic reflection tracing. Core-intersecting reflections were dated using synchronized depth-age relationships for six deep ice cores. Additional reflections were dated by matching reflections between transects and by extending reflection-inferred depth-age relationships using the local effective vertical strain rate. The oldest reflections, dating to the Eemian period, are found mostly in the northern part of the ice sheet. Within the onset regions of several fast-flowing outlet glaciers and ice streams, reflections typically do not conform to the bed topography. Disrupted radiostratigraphy is also observed in a region north of the Northeast Greenland Ice Stream that is not presently flowing rapidly. Dated reflections are used to generate a gridded age volume for most of the ice sheet and also to determine the depths of key climate transitions that were not observed directly. This radiostratigraphy provides a new constraint on the dynamics and history of the Greenland Ice Sheet. Key Points Phase information predicts reflection slope and simplifies reflection tracing Reflections can be dated away from ice cores using a simple ice flow model Radiostratigraphy is often disrupted near the onset of fast ice flow PMID:26213664

  12. Effects of habitat structure on the epifaunal community in Mussismilia corals: does coral morphology influence the richness and abundance of associated crustacean fauna?

    NASA Astrophysics Data System (ADS)

    Nogueira, Marcos M.; Neves, Elizabeth; Johnsson, Rodrigo

    2015-06-01

    Coral habitat structures increase abundance and richness of organisms by providing niches, easy access to resources and refuge from predators. Corals harbor a great variety of animals; the variation in coral species morphology contributes to the heterogeneity and complexity of habitat types. In this report, we studied the richness and abundance of crustaceans (Decapoda, Copepoda, Peracarida and Ostracoda) associated with three species of Mussismilia exhibiting different growth morphologies, in two different coral reefs of the Bahia state (Caramuanas and Boipeba-Moreré, Brazil). Mussismilia hispida is a massive coral; M. braziliensis also has a massive growth pattern, but forms a crevice in the basal area of the corallum; M. harttii has a meandroid pattern. PERMANOVA analysis suggests significant differences in associated fauna richness among Mussismilia species, with higher values for M. harttii, followed by M. braziliensis and later by M. hispida. The same trend was observed for density, except that the comparison of M. braziliensis and M. hispida did not show differences. Redundancy and canonical correspondence analysis indicated that almost all of the crustacean species were more associated with the M. harttii colonies that formed a group clearly separated from colonies of M. braziliensis and M. hispida. We also found that the internal volume of interpolyp space, only present in M. harttii, was the most important factor influencing richness and abundance of all analyzed orders of crustaceans.

  13. Plant litter and soil type drive abundance, activity and community structure of alkB harbouring microbes in different soil compartments

    PubMed Central

    Schulz, Stephan; Giebler, Julia; Chatzinotas, Antonis; Wick, Lukas Y; Fetzer, Ingo; Welzl, Gerhard; Harms, Hauke; Schloter, Michael

    2012-01-01

    Alkanes are major constituents of plant-derived waxy materials. In this study, we investigated the abundance, community structure and activity of bacteria harbouring the alkane monooxygenase gene alkB, which catalyses a major step in the pathway of aerobic alkane degradation in the litter layer, the litter–soil interface and in bulk soil at three time points during the degradation of maize and pea plant litter (2, 8 and 30 weeks) to improve our understanding about drivers for microbial performance in different soil compartments. Soil cores of different soil textures (sandy and silty) were taken from an agricultural field and incubated at constant laboratory conditions. The abundance of alkB genes and transcripts (by qPCR) as well as the community structure (by terminal restriction fragment polymorphism fingerprinting) were measured in combination with the concentrations and composition of alkanes. The results obtained indicate a clear response pattern of all investigated biotic and abiotic parameters depending on the applied litter material, the type of soil used, the time point of sampling and the soil compartment studied. As expected the distribution of alkanes of different chain length formed a steep gradient from the litter layer to the bulk soil. Mainly in the two upper soil compartments community structure and abundance patterns of alkB were driven by the applied litter type and its degradation. Surprisingly, the differences between the compartments in one soil were more pronounced than the differences between similar compartments in the two soils studied. This indicates the necessity for analysing processes in different soil compartments to improve our mechanistic understanding of the dynamics of distinct functional groups of microbes. PMID:22402403

  14. Varying contributions of growth and ageing to racial and sex differences in femoral neck structure and strength in old age.

    PubMed

    Wang, Xiao-Fang; Duan, Yunbo; Beck, Thomas J; Seeman, Ego

    2005-06-01

    The structural basis of racial and sex differences in femoral neck (FN) fragility in old age was assessed in a cross-sectional study of 829 healthy Chinese and 1181 healthy Caucasian subjects aged 18 to 93 years in Melbourne, Australia. We measured FN bone mineral density (BMD), periosteal diameter, and estimated endocortical diameter, cortical thickness, volumetric BMD (vBMD), section modulus, and buckling ratio using dual X-ray absorptiometry. Racial and sex differences in structural and strength indices were adjusted for age, bone length and body weight and were expressed in standard deviation (SD) unit. In young adulthood, Chinese women had a 0.85 SD narrower FN, a 0.47 SD thinner cortex and a 0.79 SD shorter FN axis length (FNAL) than Caucasian women. Across age, Chinese and Caucasian women had similar increments in endocortical and periosteal diameters and similar decrements in cortical thickness and vBMD (both approximately 20%). In young adult males, FN periosteal diameter did not differ by race, but cortical thickness was 0.35 SD lower in Chinese than Caucasians. Across age, increments in periosteal and endocortical diameters were less in Chinese than Caucasian men so cortical thickness and vBMD diminished less in Chinese than in Caucasian men. In both races, young adult women had narrower FN than men. As Chinese women had a greater increment in periosteal diameter than Chinese men across age, the sex difference in FN periosteal diameter established in young adulthood diminished in old age. As Caucasian men had a greater increment in periosteal diameter than Caucasian women, the sex difference in FN periosteal diameter established in young adulthood increased with age. In old age, for both sexes, Chinese had a higher fracture risk in bending than Caucasians, but a lower fracture risk by buckling. For both races, women had a higher fracture risk in bending than men. Racial and sexual dimorphism in the absolute and relative behavior of the periosteal and

  15. The 1991 International Conference on Aging Aircraft and Structural Airworthiness

    NASA Technical Reports Server (NTRS)

    Harris, Charles E. (Editor)

    1992-01-01

    Technical sessions of the conference included structural performance, nondestructive evaluation, maintenance and repair, international activities, and commuter airlines. Each session was organized to provide a well-rounded view of the subject from the industry, regulatory, and research perspective. Thirty-four presentations were given by the international technical community.

  16. AGE-RELATED DEGRADATION OF NUCLEAR POWER PLANT STRUCTURES AND COMPONENTS.

    SciTech Connect

    BRAVERMAN,J.

    1999-03-29

    This paper summarizes and highlights the results of the initial phase of a research project on the assessment of aged and degraded structures and components important to the safe operation of nuclear power plants (NPPs). A review of age-related degradation of structures and passive components at NPPs was performed. Instances of age-related degradation have been collected and reviewed. Data were collected from plant generated documents such as Licensing Event Reports, NRC generic communications, NUREGs and industry reports. Applicable cases of degradation occurrences were reviewed and then entered into a computerized database. The results obtained from the review of degradation occurrences are summarized and discussed. Various trending analyses were performed to identify which structures and components are most affected, whether degradation occurrences are worsening, and what are the most common aging mechanisms. The paper also discusses potential aging issues and degradation-susceptible structures and passive components which would have the greatest impact on plant risk.

  17. Age-Related Degradation of Nuclear Power Plant Structures and Components

    SciTech Connect

    Braverman, J.; Chang, T.-Y.; Chokshi, N.; Hofmayer, C.; Morante, R.; Shteyngart, S.

    1999-03-29

    This paper summarizes and highlights the results of the initial phase of a research project on the assessment of aged and degraded structures and components important to the safe operation of nuclear power plants (NPPs). A review of age-related degradation of structures and passive components at NPPs was performed. Instances of age-related degradation have been collected and reviewed. Data were collected from plant generated documents such as Licensing Event Reports, NRC generic communications, NUREGs and industry reports. Applicable cases of degradation occurrences were reviewed and then entered into a computerized database. The results obtained from the review of degradation occurrences are summarized and discussed. Various trending analyses were performed to identify which structures and components are most affected, whether degradation occurrences are worsening, and what was the most common aging mechanisms. The paper also discusses potential aging issues and degradation-susceptible structures and passive components which would have the greatest impact on plant risk.

  18. Aging and perceived event structure as a function of modality.

    PubMed

    Magliano, Joseph; Kopp, Kristopher; McNerney, M Windy; Radvansky, Gabriel A; Zacks, Jeffrey M

    2012-01-01

    The majority of research on situation model processing in older adults has focused on narrative texts. Much of this research has shown that many important aspects of constructing a situation model for a text are preserved and may even improve with age. However, narratives need not be text-based, and little is known as to whether these findings generalize to visually-based narratives. The present study assessed the impact of story modality on event segmentation, which is a basic component of event comprehension. Older and younger adults viewed picture stories or read text versions of them and segmented them into events. There was comparable alignment between the segmentation judgments and a theoretically guided analysis of shifts in situational features across modalities for both populations. These results suggest that situation models provide older adults with a stable basis for event comprehension across different modalities of expereinces.

  19. Antifouling Coatings Influence both Abundance and Community Structure of Colonizing Biofilms: a Case Study in the Northwestern Mediterranean Sea

    PubMed Central

    Camps, Mercedes; Barani, Aude; Gregori, Gérald; Bouchez, Agnès; Le Berre, Brigitte; Bressy, Christine; Blache, Yves

    2014-01-01

    When immersed in seawater, substrates are rapidly colonized by both micro- and macroorganisms. This process is responsible for important economic and ecological prejudices, particularly when related to ship hulls or aquaculture nets. Commercial antifouling coatings are supposed to reduce biofouling, i.e., micro- and macrofoulers. In this study, biofilms that primarily settled on seven different coatings (polyvinyl chloride [PVC], a fouling release coating [FRC], and five self-polishing copolymer coatings [SPC], including four commercial ones) were quantitatively studied, after 1 month of immersion in summer in the Toulon Bay (Northwestern Mediterranean Sea, France), by using flow cytometry (FCM), microscopy, and denaturing gradient gel electrophoresis. FCM was used after a pretreatment to separate cells from the biofilm matrix, in order to determine densities of heterotrophic bacteria, picocyanobacteria, and pico- and nanoeukaryotes on these coatings. Among diatoms, the only microphytobenthic class identified by microscopy, Licmophora, Navicula, and Nitzschia were determined to be the dominant taxa. Overall, biocide-free coatings showed higher densities than all other coatings, except for one biocidal coating, whatever the group of microorganisms. Heterotrophic bacteria always showed the highest densities, and diatoms showed the lowest, but the relative abundances of these groups varied depending on the coating. In particular, the copper-free SPC failed to prevent diatom settlement, whereas the pyrithione-free SPC exhibited high picocyanobacterial density. These results highlight the interest in FCM for antifouling coating assessment as well as specific selection among microbial communities by antifouling coatings. PMID:24907329

  20. Antifouling coatings influence both abundance and community structure of colonizing biofilms: a case study in the Northwestern Mediterranean Sea.

    PubMed

    Camps, Mercedes; Barani, Aude; Gregori, Gérald; Bouchez, Agnès; Le Berre, Brigitte; Bressy, Christine; Blache, Yves; Briand, Jean-François

    2014-08-01

    When immersed in seawater, substrates are rapidly colonized by both micro- and macroorganisms. This process is responsible for important economic and ecological prejudices, particularly when related to ship hulls or aquaculture nets. Commercial antifouling coatings are supposed to reduce biofouling, i.e., micro- and macrofoulers. In this study, biofilms that primarily settled on seven different coatings (polyvinyl chloride [PVC], a fouling release coating [FRC], and five self-polishing copolymer coatings [SPC], including four commercial ones) were quantitatively studied, after 1 month of immersion in summer in the Toulon Bay (Northwestern Mediterranean Sea, France), by using flow cytometry (FCM), microscopy, and denaturing gradient gel electrophoresis. FCM was used after a pretreatment to separate cells from the biofilm matrix, in order to determine densities of heterotrophic bacteria, picocyanobacteria, and pico- and nanoeukaryotes on these coatings. Among diatoms, the only microphytobenthic class identified by microscopy, Licmophora, Navicula, and Nitzschia were determined to be the dominant taxa. Overall, biocide-free coatings showed higher densities than all other coatings, except for one biocidal coating, whatever the group of microorganisms. Heterotrophic bacteria always showed the highest densities, and diatoms showed the lowest, but the relative abundances of these groups varied depending on the coating. In particular, the copper-free SPC failed to prevent diatom settlement, whereas the pyrithione-free SPC exhibited high picocyanobacterial density. These results highlight the interest in FCM for antifouling coating assessment as well as specific selection among microbial communities by antifouling coatings. PMID:24907329

  1. Structural damages of maxillofacial biopolymers under solar aging.

    PubMed

    Eleni, P N; Krokida, M K; Frangou, M J; Polyzois, G L; Maroulis, Z B; Marinos-Kouris, D

    2007-09-01

    Additional types of silicone biopolymers are widely used in maxillofacial prosthetics. Therefore, the knowledge of the solar radiation's effect on their structural stability is highly important. Four different industrially synthesized biomaterials were examined, called Episil Europe 1, Europe 2, Europe 3 and Africa 3, which were exposed to solar radiation (UVA, UVB) for eight different time periods (from 8 to 168 h). Structural damages due to irradiation exposure were investigated by mechanical tests (compression) and differential scanning calorimetry (DSC) methods. Simple mathematical models were developed, containing parameters with physical meaning such as maximum stress (sigma(max)), maximum strain (epsilon), elasticity parameter (E), and viscoelastic parameter (p), for the compression test, and melting temperature (T (m)) and Enthalpy in melting point (Heat) for DSC. With increasing irradiation time their maximum stress and strain decreased significantly, and the materials lost their elasticity and molecular stability. A decrement in their melting points and heats was observed as irradiation time was increasing. Finally, experimental results demonstrated that solar radiation has a severe effect on the structural stability of the examined biomaterials.

  2. Aged Muscle Demonstrates Fiber-Type Adaptations in Response to Mechanical Overload, in the Absence of Myofiber Hypertrophy, Independent of Satellite Cell Abundance.

    PubMed

    Lee, Jonah D; Fry, Christopher S; Mula, Jyothi; Kirby, Tyler J; Jackson, Janna R; Liu, Fujun; Yang, Lin; Dupont-Versteegden, Esther E; McCarthy, John J; Peterson, Charlotte A

    2016-04-01

    Although sarcopenia, age-associated loss of muscle mass and strength, is neither accelerated nor exacerbated by depletion of muscle stem cells, satellite cells, we hypothesized that adaptation in sarcopenic muscle would be compromised. To test this hypothesis, we depleted satellite cells with tamoxifen treatment of Pax7(CreER)-DTA mice at 4 months of age, and 20 months later subjected the plantaris muscle to 2 weeks of mechanical overload. We found myofiber hypertrophy was impaired in aged mice regardless of satellite cell content. Even in the absence of growth, vehicle-treated mice mounted a regenerative response, not apparent in tamoxifen-treated mice. Further, myonuclear accretion occurred in the absence of growth, which was prevented by satellite cell depletion, demonstrating that myonuclear addition is insufficient to drive myofiber hypertrophy. Satellite cell depletion increased extracellular matrix content of aged muscle that was exacerbated by overload, potentially limiting myofiber growth. These results support the idea that satellite cells regulate the muscle environment, and that their loss during aging may contribute to fibrosis, particularly during periods of remodeling. Overload induced a fiber-type composition improvement, independent of satellite cells, suggesting that aged muscle is very responsive to exercise-induced enhancement in oxidative capacity, even with an impaired hypertrophic response.

  3. Aged Muscle Demonstrates Fiber-Type Adaptations in Response to Mechanical Overload, in the Absence of Myofiber Hypertrophy, Independent of Satellite Cell Abundance.

    PubMed

    Lee, Jonah D; Fry, Christopher S; Mula, Jyothi; Kirby, Tyler J; Jackson, Janna R; Liu, Fujun; Yang, Lin; Dupont-Versteegden, Esther E; McCarthy, John J; Peterson, Charlotte A

    2016-04-01

    Although sarcopenia, age-associated loss of muscle mass and strength, is neither accelerated nor exacerbated by depletion of muscle stem cells, satellite cells, we hypothesized that adaptation in sarcopenic muscle would be compromised. To test this hypothesis, we depleted satellite cells with tamoxifen treatment of Pax7(CreER)-DTA mice at 4 months of age, and 20 months later subjected the plantaris muscle to 2 weeks of mechanical overload. We found myofiber hypertrophy was impaired in aged mice regardless of satellite cell content. Even in the absence of growth, vehicle-treated mice mounted a regenerative response, not apparent in tamoxifen-treated mice. Further, myonuclear accretion occurred in the absence of growth, which was prevented by satellite cell depletion, demonstrating that myonuclear addition is insufficient to drive myofiber hypertrophy. Satellite cell depletion increased extracellular matrix content of aged muscle that was exacerbated by overload, potentially limiting myofiber growth. These results support the idea that satellite cells regulate the muscle environment, and that their loss during aging may contribute to fibrosis, particularly during periods of remodeling. Overload induced a fiber-type composition improvement, independent of satellite cells, suggesting that aged muscle is very responsive to exercise-induced enhancement in oxidative capacity, even with an impaired hypertrophic response. PMID:25878030

  4. Interplay between Shear Loading and Structural Aging in a Physical Gelatin Gel

    SciTech Connect

    Ronsin, O.; Caroli, C.; Baumberger, T.

    2009-09-25

    We show that the aging of the mechanical relaxation of a gelatin gel exhibits the same scaling phenomenology as polymer and colloidal glasses. In addition, gelatin is known to exhibit logarithmic structural aging (stiffening). We find that stress accelerates this process. However, this effect is definitely irreducible to a mere age shift with respect to natural aging. We suggest that it is interpretable in terms of elastically aided elementary (coil->helix) local events whose dynamics gradually slows down as aging increases geometric frustration.

  5. Continuous Age-Structured Model for Bovine Tuberculosis in African buffalo

    NASA Astrophysics Data System (ADS)

    Anguelov, R.; Kojouharov, H.

    2009-10-01

    The paper deals with a model of the spread of bovine tuberculosis in the buffalo population in the Kruger National Park in South Africa. The model uses continuous age structure and it is formulated in terms of partial differential equations using eight epidemiological classes (compartments). More precisely, the age density for each class at time t satisfies a one way wave equation, where the age is the space variable. The continuous age model discussed here is derived from a 2006 age groups model by P. C. Cross and W. M. Getz.

  6. Geroprotectors.org: a new, structured and curated database of current therapeutic interventions in aging and age-related disease.

    PubMed

    Moskalev, Alexey; Chernyagina, Elizaveta; de Magalhães, João Pedro; Barardo, Diogo; Thoppil, Harikrishnan; Shaposhnikov, Mikhail; Budovsky, Arie; Fraifeld, Vadim E; Garazha, Andrew; Tsvetkov, Vasily; Bronovitsky, Evgeny; Bogomolov, Vladislav; Scerbacov, Alexei; Kuryan, Oleg; Gurinovich, Roman; Jellen, Leslie C; Kennedy, Brian; Mamoshina, Polina; Dobrovolskaya, Evgeniya; Aliper, Alex; Kaminsky, Dmitry; Zhavoronkov, Alex

    2015-09-01

    As the level of interest in aging research increases, there is a growing number of geroprotectors, or therapeutic interventions that aim to extend the healthy lifespan and repair or reduce aging-related damage in model organisms and, eventually, in humans. There is a clear need for a manually-curated database of geroprotectors to compile and index their effects on aging and age-related diseases and link these effects to relevant studies and multiple biochemical and drug databases. Here, we introduce the first such resource, Geroprotectors (http://geroprotectors.org). Geroprotectors is a public, rapidly explorable database that catalogs over 250 experiments involving over 200 known or candidate geroprotectors that extend lifespan in model organisms. Each compound has a comprehensive profile complete with biochemistry, mechanisms, and lifespan effects in various model organisms, along with information ranging from chemical structure, side effects, and toxicity to FDA drug status. These are presented in a visually intuitive, efficient framework fit for casual browsing or in-depth research alike. Data are linked to the source studies or databases, providing quick and convenient access to original data. The Geroprotectors database facilitates cross-study, cross-organism, and cross-discipline analysis and saves countless hours of inefficient literature and web searching. Geroprotectors is a one-stop, knowledge-sharing, time-saving resource for researchers seeking healthy aging solutions. PMID:26342919

  7. Geroprotectors.org: a new, structured and curated database of current therapeutic interventions in aging and age-related disease.

    PubMed

    Moskalev, Alexey; Chernyagina, Elizaveta; de Magalhães, João Pedro; Barardo, Diogo; Thoppil, Harikrishnan; Shaposhnikov, Mikhail; Budovsky, Arie; Fraifeld, Vadim E; Garazha, Andrew; Tsvetkov, Vasily; Bronovitsky, Evgeny; Bogomolov, Vladislav; Scerbacov, Alexei; Kuryan, Oleg; Gurinovich, Roman; Jellen, Leslie C; Kennedy, Brian; Mamoshina, Polina; Dobrovolskaya, Evgeniya; Aliper, Alex; Kaminsky, Dmitry; Zhavoronkov, Alex

    2015-09-01

    As the level of interest in aging research increases, there is a growing number of geroprotectors, or therapeutic interventions that aim to extend the healthy lifespan and repair or reduce aging-related damage in model organisms and, eventually, in humans. There is a clear need for a manually-curated database of geroprotectors to compile and index their effects on aging and age-related diseases and link these effects to relevant studies and multiple biochemical and drug databases. Here, we introduce the first such resource, Geroprotectors (http://geroprotectors.org). Geroprotectors is a public, rapidly explorable database that catalogs over 250 experiments involving over 200 known or candidate geroprotectors that extend lifespan in model organisms. Each compound has a comprehensive profile complete with biochemistry, mechanisms, and lifespan effects in various model organisms, along with information ranging from chemical structure, side effects, and toxicity to FDA drug status. These are presented in a visually intuitive, efficient framework fit for casual browsing or in-depth research alike. Data are linked to the source studies or databases, providing quick and convenient access to original data. The Geroprotectors database facilitates cross-study, cross-organism, and cross-discipline analysis and saves countless hours of inefficient literature and web searching. Geroprotectors is a one-stop, knowledge-sharing, time-saving resource for researchers seeking healthy aging solutions.

  8. Geroprotectors.org: a new, structured and curated database of current therapeutic interventions in aging and age-related disease

    PubMed Central

    Moskalev, Alexey; Chernyagina, Elizaveta; de Magalhães, João Pedro; Barardo, Diogo; Thoppil, Harikrishnan; Shaposhnikov, Mikhail; Budovsky, Arie; Fraifeld, Vadim E.; Garazha, Andrew; Tsvetkov, Vasily; Bronovitsky, Evgeny; Bogomolov, Vladislav; Scerbacov, Alexei; Kuryan, Oleg; Gurinovich, Roman; Jellen, Leslie C.; Kennedy, Brian; Mamoshina, Polina; Dobrovolskaya, Evgeniya; Aliper, Alex; Kaminsky, Dmitry; Zhavoronkov, Alex

    2015-01-01

    As the level of interest in aging research increases, there is a growing number of geroprotectors, or therapeutic interventions that aim to extend the healthy lifespan and repair or reduce aging-related damage in model organisms and, eventually, in humans. There is a clear need for a manually-curated database of geroprotectors to compile and index their effects on aging and age-related diseases and link these effects to relevant studies and multiple biochemical and drug databases. Here, we introduce the first such resource, Geroprotectors (http://geroprotectors.org). Geroprotectors is a public, rapidly explorable database that catalogs over 250 experiments involving over 200 known or candidate geroprotectors that extend lifespan in model organisms. Each compound has a comprehensive profile complete with biochemistry, mechanisms, and lifespan effects in various model organisms, along with information ranging from chemical structure, side effects, and toxicity to FDA drug status. These are presented in a visually intuitive, efficient framework fit for casual browsing or in-depth research alike. Data are linked to the source studies or databases, providing quick and convenient access to original data. The Geroprotectors database facilitates cross-study, cross-organism, and cross-discipline analysis and saves countless hours of inefficient literature and web searching. Geroprotectors is a one-stop, knowledge-sharing, time-saving resource for researchers seeking healthy aging solutions. PMID:26342919

  9. Effects of aging on processing of novel musical structure.

    PubMed

    Lynch, M P; Steffens, M L

    1994-07-01

    Musical processing involves long-term memory representations of invariant properties of auditory patterns and working memory representations of patterns heard in the present moment. Musical scales are formalized sets of pitches on which much of musical composition and improvisation is based, and frequency relations among scale notes are invariant within categorical boundaries. Studies of young adults have indicated that adjustments of frequency relations are better detected when melodies are based on culturally familiar scales than on culturally unfamiliar scales. A proposed account for this finding has been that knowledge about musical frequency relations is stored in long-term memory. In the present study, old and young adults performed equivalently well in detection of frequency relation adjustments in a culturally familiar scale context, but young adults performed better than old adults in culturally unfamiliar scale contexts. The performance of old adults in a culturally unfamiliar scale context was correlated with high-frequency (8 kHz) hearing sensitivity. These findings suggest that influences of aging on processing of auditory events involve relations of auditory cognition and hearing sensitivity.

  10. Microbial community structure and abundance in the rhizosphere and bulk soil of a tomato cropping system that includes cover crops

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this report we use Terminal Restriction Fragment Length Polymorphisms (TRFLP) in a tomato production system to “finger printing” the soil microbial community structure with Phylum specific primer sets. Factors influencing the soil microbes are a cover crop of Hairy Vetch (Vicia villosa) or Rye (...

  11. Association of structural global brain network properties with intelligence in normal aging.

    PubMed

    Fischer, Florian U; Wolf, Dominik; Scheurich, Armin; Fellgiebel, Andreas

    2014-01-01

    Higher general intelligence attenuates age-associated cognitive decline and the risk of dementia. Thus, intelligence has been associated with cognitive reserve or resilience in normal aging. Neurophysiologically, intelligence is considered as a complex capacity that is dependent on a global cognitive network rather than isolated brain areas. An association of structural as well as functional brain network characteristics with intelligence has already been reported in young adults. We investigated the relationship between global structural brain network properties, general intelligence and age in a group of 43 cognitively healthy elderly, age 60-85 years. Individuals were assessed cross-sectionally using Wechsler Adult Intelligence Scale-Revised (WAIS-R) and diffusion-tensor imaging. Structural brain networks were reconstructed individually using deterministic tractography, global network properties (global efficiency, mean shortest path length, and clustering coefficient) were determined by graph theory and correlated to intelligence scores within both age groups. Network properties were significantly correlated to age, whereas no significant correlation to WAIS-R was observed. However, in a subgroup of 15 individuals aged 75 and above, the network properties were significantly correlated to WAIS-R. Our findings suggest that general intelligence and global properties of structural brain networks may not be generally associated in cognitively healthy elderly. However, we provide first evidence of an association between global structural brain network properties and general intelligence in advanced elderly. Intelligence might be affected by age-associated network deterioration only if a certain threshold of structural degeneration is exceeded. Thus, age-associated brain structural changes seem to be partially compensated by the network and the range of this compensation might be a surrogate of cognitive reserve or brain resilience.

  12. Estimating survival rates with time series of standing age-structure data.

    PubMed

    Udevitz, Mark S; Gogan, Peter J P

    2012-04-01

    It has long been recognized that age-structure data contain useful information for assessing the status and dynamics of wildlife populations. For example, age-specific survival rates can be estimated with just a single sample from the age distribution of a stable, stationary population. For a population that is not stable, age-specific survival rates can be estimated using techniques such as inverse methods that combine time series of age-structure data with other demographic data. However, estimation of survival rates using these methods typically requires numerical optimization, a relatively long time series of data, and smoothing or other constraints to provide useful estimates. We developed general models for possibly unstable populations that combine time series of age-structure data with other demographic data to provide explicit maximum likelihood estimators of age-specific survival rates with as few as two years of data. As an example, we applied these methods to estimate survival rates for female bison (Bison bison) in Yellowstone National Park, USA. This approach provides a simple tool for monitoring survival rates based on age-structure data.

  13. Structural hippocampal network alterations during healthy aging: a multi-modal MRI study

    PubMed Central

    Pelletier, Amandine; Periot, Olivier; Dilharreguy, Bixente; Hiba, Bassem; Bordessoules, Martine; Pérès, Karine; Amieva, Hélène; Dartigues, Jean-François; Allard, Michèle; Catheline, Gwénaëlle

    2013-01-01

    While hippocampal atrophy has been described during healthy aging, few studies have examined its relationship with the integrity of White Matter (WM) connecting tracts of the limbic system. This investigation examined WM structural damage specifically related to hippocampal atrophy in healthy aging subjects (n = 129), using morphological MRI to assess hippocampal volume and Diffusion Tensor Imaging (DTI) to assess WM integrity. Subjects with Mild Cognitive Impairment (MCI) or dementia were excluded from the analysis. In our sample, increasing age was significantly associated with reduced hippocampal volume and reduced Fractional Anisotropy (FA) at the level of the fornix and the cingulum bundle. The findings also demonstrate that hippocampal atrophy was specifically associated with reduced FA of the fornix bundle, but it was not related to alteration of the cingulum bundle. Our results indicate that the relationship between hippocampal atrophy and fornix FA values is not due to an independent effect of age on both structures. A recursive regression procedure was applied to evaluate sequential relationships between the alterations of these two brain structures. When both hippocampal atrophy and fornix FA values were included in the same model to predict age, fornix FA values remained significant whereas hippocampal atrophy was no longer significantly associated with age. According to this latter finding, hippocampal atrophy in healthy aging could be mediated by a loss of fornix connections. Structural alterations of this part of the limbic system, which have been associated with neurodegeneration in Alzheimer's disease, result at least in part from the aging process. PMID:24367331

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

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

    This viewgraph report presents an examination of the fracture toughness of aluminum-lithium alloy C458 for use in cryotank structures. Topics cover include: cryogenics, alloy composition, strengthing precipitates in C458, cryogenic fracture toughness improvements, design of experiments for measuring aging optimization of C458 plate and effects of aging of properties of C458 plate.

  15. Factor Structure of Attention Deficit Hyperactivity Disorder Symptoms for Children Age 3 to 5 Years

    ERIC Educational Resources Information Center

    McGoey, Kara E.; Schreiber, James; Venesky, Lindsey; Westwood, Wendy; McGuirk, Lindsay; Schaffner, Kristen

    2015-01-01

    The diagnosis of attention deficit hyperactivity disorder (ADHD) distinguishes two dimensions of symptoms, inattention and hyperactivity-impulsivity for ages 3 to adulthood. Currently, no separate classification for preschool-age children exists, whereas preliminary research suggests that the two-factor structure of ADHD may not match the…

  16. Estimating survival rates with time series of standing age-structure data

    USGS Publications Warehouse

    Udevitz, Mark S.; Gogan, Peter J.

    2014-01-01

    It has long been recognized that age-structure data contain useful information for assessing the status and dynamics of wildlife populations. For example, age-specific survival rates can be estimated with just a single sample from the age distribution of a stable, stationary population. For a population that is not stable, age-specific survival rates can be estimated using techniques such as inverse methods that combine time series of age-structure data with other demographic data. However, estimation of survival rates using these methods typically requires numerical optimization, a relatively long time series of data, and smoothing or other constraints to provide useful estimates. We developed general models for possibly unstable populations that combine time series of age-structure data with other demographic data to provide explicit maximum likelihood estimators of age-specific survival rates with as few as two years of data. As an example, we applied these methods to estimate survival rates for female bison (Bison bison) in Yellowstone National Park, USA. This approach provides a simple tool for monitoring survival rates based on age-structure data.

  17. The evolution of oscillatory behavior in age-structured species.

    PubMed

    Greenman, J V; Benton, T G; Boots, M; White, A R

    2005-07-01

    A major challenge in ecology is to explain why so many species show oscillatory population dynamics and why the oscillations commonly occur with particular periods. The background environment, through noise or seasonality, is one possible driver of these oscillations, as are the components of the trophic web with which the species interacts. However, the oscillation may also be intrinsic, generated by density-dependent effects on the life history. Models of structured single-species systems indicate that a much broader range of oscillatory behavior than that seen in nature is theoretically possible. We test the hypothesis that it is selection that acts to constrain the range of periods. We analyze a nonlinear single-species matrix model with density dependence affecting reproduction and with trade-offs between reproduction and survival. We show that the evolutionarily stable state is oscillatory and has a period roughly twice the time to maturation, in line with observed patterns of periodicity. The robustness of this result to variations in trade-off function and density dependence is tested.

  18. Does white matter structure or hippocampal volume mediate associations between cortisol and cognitive ageing?

    PubMed Central

    Cox, Simon R.; MacPherson, Sarah E.; Ferguson, Karen J.; Royle, Natalie A.; Maniega, Susana Muñoz; Hernández, Maria del C. Valdés; Bastin, Mark E.; MacLullich, Alasdair M.J.; Wardlaw, Joanna M.; Deary, Ian J.

    2015-01-01

    Elevated glucocorticoid (GC) levels putatively damage specific brain regions, which in turn may accelerate cognitive ageing. However, many studies are cross-sectional or have relatively short follow-up periods, making it difficult to relate GCs directly to changes in cognitive ability with increasing age. Moreover, studies combining endocrine, MRI and cognitive variables are scarce, measurement methods vary considerably, and formal tests of the underlying causal hypothesis (cortisol → brain → cognition) are absent. In this study, 90 men, aged 73 years, provided measures of fluid intelligence, processing speed and memory, diurnal and reactive salivary cortisol and two measures of white matter (WM) structure (WM hyperintensity volume from structural MRI and mean diffusivity averaged across 12 major tracts from diffusion tensor MRI), hippocampal volume, and also cognitive ability at age 11. We tested whether negative relationships between cognitive ageing differences (over more than 60 years) and salivary cortisol were significantly mediated by WM and hippocampal volume. Significant associations between reactive cortisol at 73 and cognitive ageing differences between 11 and 73 (r = −.28 to −.36, p < .05) were partially mediated by both WM structural measures, but not hippocampal volume. Cortisol-WM relationships were modest, as was the degree to which WM structure attenuated cortisol–cognition associations (<15%). These data support the hypothesis that GCs contribute to cognitive ageing differences from childhood to the early 70s, partly via brain WM structure. PMID:26298692

  19. Does white matter structure or hippocampal volume mediate associations between cortisol and cognitive ageing?

    PubMed

    Cox, Simon R; MacPherson, Sarah E; Ferguson, Karen J; Royle, Natalie A; Maniega, Susana Muñoz; Hernández, Maria Del C Valdés; Bastin, Mark E; MacLullich, Alasdair M J; Wardlaw, Joanna M; Deary, Ian J

    2015-12-01

    Elevated glucocorticoid (GC) levels putatively damage specific brain regions, which in turn may accelerate cognitive ageing. However, many studies are cross-sectional or have relatively short follow-up periods, making it difficult to relate GCs directly to changes in cognitive ability with increasing age. Moreover, studies combining endocrine, MRI and cognitive variables are scarce, measurement methods vary considerably, and formal tests of the underlying causal hypothesis (cortisol→brain→cognition) are absent. In this study, 90 men, aged 73 years, provided measures of fluid intelligence, processing speed and memory, diurnal and reactive salivary cortisol and two measures of white matter (WM) structure (WM hyperintensity volume from structural MRI and mean diffusivity averaged across 12 major tracts from diffusion tensor MRI), hippocampal volume, and also cognitive ability at age 11. We tested whether negative relationships between cognitive ageing differences (over more than 60 years) and salivary cortisol were significantly mediated by WM and hippocampal volume. Significant associations between reactive cortisol at 73 and cognitive ageing differences between 11 and 73 (r=-.28 to -.36, p<.05) were partially mediated by both WM structural measures, but not hippocampal volume. Cortisol-WM relationships were modest, as was the degree to which WM structure attenuated cortisol-cognition associations (<15%). These data support the hypothesis that GCs contribute to cognitive ageing differences from childhood to the early 70s, partly via brain WM structure. PMID:26298692

  20. Catalytic activities enhanced by abundant structural defects and balanced N distribution of N-doped graphene in oxygen reduction reaction

    NASA Astrophysics Data System (ADS)

    Bai, Xiaogong; Shi, Yantao; Guo, Jiahao; Gao, Liguo; Wang, Kai; Du, Yi; Ma, Tingli

    2016-02-01

    N-doped graphene (NG) is a promising candidate for oxygen reduction reaction (ORR) in the cathode of fuel cells. However, the catalytic activity of NG is lower than that of commercial Pt/C in alkaline and acidic media. In this study, NG samples were obtained using urea as N source. The structural defects and N distribution in the samples were adjusted by regulating the pyrolysis temperature. The new NG type exhibited remarkable catalytic activities for ORR in both alkaline and acidic media.

  1. Microbial communities on glacier surfaces in Svalbard: impact of physical and chemical properties on abundance and structure of cyanobacteria and algae.

    PubMed

    Stibal, Marek; Sabacká, Marie; Kastovská, Klára

    2006-11-01

    Microbial communities occurring in three types of supraglacial habitats--cryoconite holes, medial moraines, and supraglacial kames--at several glaciers in the Arctic archipelago of Svalbard were investigated. Abundance, biovolume, and community structure were evaluated by using epifluorescence microscopy and culturing methods. Particular emphasis was laid on distinctions in the chemical and physical properties of the supraglacial habitats and their relation to the microbial communities, and quantitative multivariate analyses were used to assess potential relationships. Varying pH (4.8 in cryoconite; 8.5 in a moraine) and texture (the proportion of coarse fraction 2% of dry weight in cryoconite; 99% dw in a kame) were found, and rather low concentrations of organic matter (0.3% of dry weight in a kame; 22% dw in cryoconite) and nutrients (nitrogen up to 0.4% dw, phosphorus up to 0.8% dw) were determined in the samples. In cryoconite sediment, the highest numbers of bacteria, cyanobacteria, and algae were found, whereas relatively low microbial abundances were recorded in moraines and kames. Cyanobacterial cells were significantly more abundant than microalgal ones in cryoconite and supraglacial kames. Different species of the cyanobacterial genus Leptolyngbya were by far the most represented in all samples, and cyanobacteria of the genera Phormidium and Nostoc prevailed in cultures isolated from cryoconite samples. These species are considered opportunistic organisms with wide ecological valency and strong colonizing potential rather than glacial specialists. Statistical analyses suggest that fine sediment with higher water content is the most suitable condition for bacteria, cyanobacteria, and algae. Also, a positive impact of lower pH on microbial growth was found. The fate of a microbial cell deposited on the glacier surface seems therefore predetermined by the physical and chemical factors such as texture of sediment and water content rather than spatial factors

  2. Microbial communities on glacier surfaces in Svalbard: impact of physical and chemical properties on abundance and structure of cyanobacteria and algae.

    PubMed

    Stibal, Marek; Sabacká, Marie; Kastovská, Klára

    2006-11-01

    Microbial communities occurring in three types of supraglacial habitats--cryoconite holes, medial moraines, and supraglacial kames--at several glaciers in the Arctic archipelago of Svalbard were investigated. Abundance, biovolume, and community structure were evaluated by using epifluorescence microscopy and culturing methods. Particular emphasis was laid on distinctions in the chemical and physical properties of the supraglacial habitats and their relation to the microbial communities, and quantitative multivariate analyses were used to assess potential relationships. Varying pH (4.8 in cryoconite; 8.5 in a moraine) and texture (the proportion of coarse fraction 2% of dry weight in cryoconite; 99% dw in a kame) were found, and rather low concentrations of organic matter (0.3% of dry weight in a kame; 22% dw in cryoconite) and nutrients (nitrogen up to 0.4% dw, phosphorus up to 0.8% dw) were determined in the samples. In cryoconite sediment, the highest numbers of bacteria, cyanobacteria, and algae were found, whereas relatively low microbial abundances were recorded in moraines and kames. Cyanobacterial cells were significantly more abundant than microalgal ones in cryoconite and supraglacial kames. Different species of the cyanobacterial genus Leptolyngbya were by far the most represented in all samples, and cyanobacteria of the genera Phormidium and Nostoc prevailed in cultures isolated from cryoconite samples. These species are considered opportunistic organisms with wide ecological valency and strong colonizing potential rather than glacial specialists. Statistical analyses suggest that fine sediment with higher water content is the most suitable condition for bacteria, cyanobacteria, and algae. Also, a positive impact of lower pH on microbial growth was found. The fate of a microbial cell deposited on the glacier surface seems therefore predetermined by the physical and chemical factors such as texture of sediment and water content rather than spatial factors

  3. Bacterial and archaeal symbionts in the South China Sea sponge Phakellia fusca: community structure, relative abundance, and ammonia-oxidizing populations.

    PubMed

    Han, Minqi; Liu, Fang; Zhang, Fengli; Li, Zhiyong; Lin, Houwen

    2012-12-01

    Many biologically active natural products have been isolated from Phakellia fusca, an indigenous sponge in the South China Sea; however, the microbial symbionts of Phakellia fusca remain unknown. The present investigations on sponge microbial community are mainly based on qualitative analysis, while quantitative analysis, e.g., relative abundance, is rarely carried out, and little is known about the roles of microbial symbionts. In this study, the community structure and relative abundance of bacteria, actinobacteria, and archaea associated with Phakellia fusca were revealed by 16S rRNA gene library-based sequencing and quantitative real time PCR (qRT-PCR). The ammonia-oxidizing populations were investigated based on amoA gene and anammox-specific 16S rRNA gene libraries. As a result, it was found that bacterial symbionts of sponge Phakellia fusca consist of Proteobacteria including Gamma-, Alpha-, and Delta-proteobacteria, Cyanobacteria with Gamma-proteobacteria as the predominant components. In particular, the diversity of actinobacterial symbionts in Phakellia fusca is high, which is composed of Corynebacterineae, Acidimicrobidae, Frankineae, Micrococcineae, and Streptosporangineae. All the observed archaea in sponge Phakellia fusca belong to Crenarchaeota, and the detected ammonia-oxidizing populations are ammonia-oxidizing archaea, suggesting the nitrification function of sponge archaeal symbionts. According to qRT-PCR analysis, bacterial symbionts dominated the microbial community, while archaea represented the second predominant symbionts, followed by actinobacteria. The revealed diverse prokaryotic symbionts of Phakellia fusca are valuable for the understanding and in-depth utilization of Phakellia fusca microbial symbionts. This study extends our knowledge of the community, especially the relative abundance of microbial symbionts in sponges.

  4. Abundance and Diversity of Crypto- and Necto-Benthic Coastal Fish Are Higher in Marine Forests than in Structurally Less Complex Macroalgal Assemblages

    PubMed Central

    Thiriet, Pierre D.; Cheminée, Adrien; Guidetti, Paolo; Bianchimani, Olivier; Basthard-Bogain, Solène; Cottalorda, Jean-Michel; Arceo, Hazel; Moranta, Joan; Lejeune, Pierre; Francour, Patrice; Mangialajo, Luisa

    2016-01-01

    In Mediterranean subtidal rocky reefs, Cystoseira spp. (Phaeophyceae) form dense canopies up to 1 m high. Such habitats, called ‘Cystoseira forests’, are regressing across the entire Mediterranean Sea due to multiple anthropogenic stressors, as are other large brown algae forests worldwide. Cystoseira forests are being replaced by structurally less complex habitats, but little information is available regarding the potential difference in the structure and composition of fish assemblages between these habitats. To fill this void, we compared necto-benthic (NB) and crypto-benthic (CB) fish assemblage structures between Cystoseira forests and two habitats usually replacing the forests (turf and barren), in two sampling regions (Corsica and Menorca). We sampled NB fish using Underwater Visual Census (UVC) and CB fish using Enclosed Anaesthetic Station Vacuuming (EASV), since UVC is known to underestimate the diversity and density of the ‘hard to spot’ CB fish. We found that both taxonomic diversity and total density of NB and CB fish were highest in Cystoseira forests and lowest in barrens, while turfs, that could be sampled only at Menorca, showed intermediate values. Conversely, total biomass of NB and CB fish did not differ between habitats because the larger average size of fish in barrens (and turfs) compensated for their lower densities. The NB families Labridae and Serranidae, and the CB families Blenniidae, Cliniidae, Gobiidae, Trypterigiidae and Scorpaenidae, were more abundant in forests. The NB taxa Diplodus spp. and Thalassoma pavo were more abundant in barrens. Our study highlights the importance of using EASV for sampling CB fish, and shows that Cystoseira forests support rich and diversified fish assemblages. This evidence suggests that the ongoing loss of Cystoseira forests may impair coastal fish assemblages and related goods and services to humans, and stresses the need to implement strategies for the successful conservation and/or recovery

  5. A realistic age structured transmission model for dengue hemorrhagic fever in Thailand.

    PubMed

    Pongsumpun, P; Tang, I M

    2001-06-01

    The influence of age structure in the susceptible class of the Susceptible-Infected Recovered (SIR) model used to describe the transmission of dengue hemorrhagic fever (DHF) was studied. This was done by first dividing all of the population classes into cohorts and then writing a set of coupled SIR equations for each cohort. The consequences of assuming different behavior of the transmission rates on the age structure in the DHF incidence rates were determined. In order for the predicted incidence rates to be similar to the DHF incidence patterns observed in several provinces in Thailand during the DHF epidemic in 1998, the transmission rates should be age dependent.

  6. Abundance coefficients, a new method for measuring microorganism relative abundance

    USGS Publications Warehouse

    Forester, R.M.

    1977-01-01

    A new method of measuring the relative abundance of microorganisms by using a set of interrelated coefficients, termed 'abundance coefficients' or 'AC', is proposed. These coefficients provide a means of recording abundance for geometric density categories, and each density measurement represents an approximation of the Poisson parameter ??t. The AC is the natural logarithm of a 'characteristic value,' which is a particular number for each geometric density category. The 'characteristic values' are based upon a probabilistic error statement derived from the Poisson formula, and they present evidence for separation of the geometric category boundaries by e = 2.71828. The proposed AC provide a means for recording species abundance in a manner suitable for arithmetic manipulation, for population structure studies, and for the determination of practical limits for defining the presence or absence of a species. Further, these coefficients provide for both intrasample and intersample abundance comparisons. ?? 1977 Plenum Publishing Corporation.

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

    NASA Astrophysics Data System (ADS)

    Graciani Rodrigues, C. C.; Espíndola, Aquino L.; Penna, T. J. P.

    2015-06-01

    In this work we present an agent-based computational model to study the spreading of the tuberculosis (TB) disease on age-structured populations. The model proposed is a merge of two previous models: an agent-based computational model for the spreading of tuberculosis and a bit-string model for biological aging. The combination of TB with the population aging, reproduces the coexistence of health states, as seen in real populations. In addition, the universal exponential behavior of mortalities curves is still preserved. Finally, the population distribution as function of age shows the prevalence of TB mostly in elders, for high efficacy treatments.

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

    PubMed Central

    Agusto, Folashade B.; Easley, Shamise; Freeman, Kenneth; Thomas, Madison

    2016-01-01

    We developed a new age-structured deterministic model for the transmission dynamics of chikungunya virus. The model is analyzed to gain insights into the qualitative features of its associated equilibria. Some of the theoretical and epidemiological findings indicate that the stable disease-free equilibrium is globally asymptotically stable when the associated reproduction number is less than unity. Furthermore, the model undergoes, in the presence of disease induced mortality, the phenomenon of backward bifurcation, where the stable disease-free equilibrium of the model coexists with a stable endemic equilibrium when the associated reproduction number is less than unity. Further analysis of the model indicates that the qualitative dynamics of the model are not altered by the inclusion of age structure. This is further emphasized by the sensitivity analysis results, which shows that the dominant parameters of the model are not altered by the inclusion of age structure. However, the numerical simulations show the flaw of the exclusion of age in the transmission dynamics of chikungunya with regard to control implementations. The exclusion of age structure fails to show the age distribution needed for an effective age based control strategy, leading to a one size fits all blanket control for the entire population. PMID:27190548

  9. [Variability in the relative abundance, size structure and sex ratio of the dolphinfish Coryphaena hippurus (Pisces: Coryphaenidae) in the Gulf of Tehuantepec, México].

    PubMed

    Alejo-Plata, Carmen; Gómez, José Luis; Serrano-Guzmán, Saúl J

    2014-06-01

    Variability in the relative abundance, size structure and sex ratio of the dolphinfish Coryphaena hippurus (Pisces: Coryphaenidae) in the Gulf of Tehuantepec, México. The dolphinfish (Coryphaena hippurus), is an oceanic epipelagic fish found worldwide in tropical and subtropical waters, with a high dispersal capability via large-scale migrations. This fast-swimming top-level predator is abundant in the Gulf of Tehuantepec, where it is caught incidentally by artisanal fisheries, and represents a target species for both recreational and commercial fisheries in Mexico, Ecuador, Peru and Central America. Nowadays, local fishery information on this species is scarce, thus our objective was to analyze the size structure by sex and the catch-per-unit-effort (CPUE) tendency of dolphinfish caught in the Gulf of Tehuantepec, from 2000 to 2007. For this, fishery catches information was obtained from the artisanal fleet, at six landing sites in the Gulf, and the sex ratio, fork length (FL) and the catch per unit effort (CPUE) were estimated. From all sampling sites, a total of 3 494 females, and 3 877 males were obtained, and dolphinfish size as fork length (FL) ranged from 20.5 to 152cm. Fish size ranged from 25.5 to 148cm furcal length (FL) in males, and 20.5 to 129cm FL in females. The sex ratio (males:females) was 1:1, except in April-May (1:1.5, p < 0.05) and November (1:0.5, p < 0.05). The sex ratio at different size classes showed a significant bias towards females at smaller sizes (< 75cm FL), whereas the males were predominant in larger size classes (> 100cm FL). The size structure was bimodal, with a variation in the size average; the modes were defined as the small group (FL = 50-55cm) and the large size group (FL = 100-110cm). The CPUE showed seasonal changes: values were high for the November-December period, and values were lower for July-August. The seasonal and inter annual variation in the abundance of dolphinfish is probably related to a pre

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

    PubMed

    Campbell, Stuart A; Stastny, Michael

    2015-03-01

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

  11. IMPROVED V II log(gf) VALUES, HYPERFINE STRUCTURE CONSTANTS, AND ABUNDANCE DETERMINATIONS IN THE PHOTOSPHERES OF THE SUN AND METAL-POOR STAR HD 84937

    SciTech Connect

    Wood, M. P.; Lawler, J. E.; Den Hartog, E. A.; Sneden, C.; Cowan, J. J. E-mail: jelawler@wisc.edu E-mail: chris@verdi.as.utexas.edu

    2014-10-01

    New experimental absolute atomic transition probabilities are reported for 203 lines of V II. Branching fractions are measured from spectra recorded using a Fourier transform spectrometer and an echelle spectrometer. The branching fractions are normalized with radiative lifetime measurements to determine the new transition probabilities. Generally good agreement is found between this work and previously reported V II transition probabilities. Two spectrometers, independent radiometric calibration methods, and independent data analysis routines enable a reduction in systematic uncertainties, in particular those due to optical depth errors. In addition, new hyperfine structure constants are measured for selected levels by least squares fitting line profiles in the FTS spectra. The new V II data are applied to high resolution visible and UV spectra of the Sun and metal-poor star HD 84937 to determine new, more accurate V abundances. Lines covering a range of wavelength and excitation potential are used to search for non-LTE effects. Very good agreement is found between our new solar photospheric V abundance, log ε(V) = 3.95 from 15 V II lines, and the solar-system meteoritic value. In HD 84937, we derive [V/H] = –2.08 from 68 lines, leading to a value of [V/Fe] = 0.24.

  12. Genome-wide identification, structural analysis and new insights into late embryogenesis abundant (LEA) gene family formation pattern in Brassica napus

    PubMed Central

    Liang, Yu; Xiong, Ziyi; Zheng, Jianxiao; Xu, Dongyang; Zhu, Zeyang; Xiang, Jun; Gan, Jianping; Raboanatahiry, Nadia; Yin, Yongtai; Li, Maoteng

    2016-01-01

    Late embryogenesis abundant (LEA) proteins are a diverse and large group of polypeptides that play important roles in desiccation and freezing tolerance in plants. The LEA family has been systematically characterized in some plants but not Brassica napus. In this study, 108 BnLEA genes were identified in the B. napus genome and classified into eight families based on their conserved domains. Protein sequence alignments revealed an abundance of alanine, lysine and glutamic acid residues in BnLEA proteins. The BnLEA gene structure has few introns (<3), and they are distributed unevenly across all 19 chromosomes in B. napus, occurring as gene clusters in chromosomes A9, C2, C4 and C5. More than two-thirds of the BnLEA genes are associated with segmental duplication. Synteny analysis revealed that most LEA genes are conserved, although gene losses or gains were also identified. These results suggest that segmental duplication and whole-genome duplication played a major role in the expansion of the BnLEA gene family. Expression profiles analysis indicated that expression of most BnLEAs was increased in leaves and late stage seeds. This study presents a comprehensive overview of the LEA gene family in B. napus and provides new insights into the formation of this family. PMID:27072743

  13. Genome-wide identification, structural analysis and new insights into late embryogenesis abundant (LEA) gene family formation pattern in Brassica napus.

    PubMed

    Liang, Yu; Xiong, Ziyi; Zheng, Jianxiao; Xu, Dongyang; Zhu, Zeyang; Xiang, Jun; Gan, Jianping; Raboanatahiry, Nadia; Yin, Yongtai; Li, Maoteng

    2016-01-01

    Late embryogenesis abundant (LEA) proteins are a diverse and large group of polypeptides that play important roles in desiccation and freezing tolerance in plants. The LEA family has been systematically characterized in some plants but not Brassica napus. In this study, 108 BnLEA genes were identified in the B. napus genome and classified into eight families based on their conserved domains. Protein sequence alignments revealed an abundance of alanine, lysine and glutamic acid residues in BnLEA proteins. The BnLEA gene structure has few introns (<3), and they are distributed unevenly across all 19 chromosomes in B. napus, occurring as gene clusters in chromosomes A9, C2, C4 and C5. More than two-thirds of the BnLEA genes are associated with segmental duplication. Synteny analysis revealed that most LEA genes are conserved, although gene losses or gains were also identified. These results suggest that segmental duplication and whole-genome duplication played a major role in the expansion of the BnLEA gene family. Expression profiles analysis indicated that expression of most BnLEAs was increased in leaves and late stage seeds. This study presents a comprehensive overview of the LEA gene family in B. napus and provides new insights into the formation of this family. PMID:27072743

  14. Quota implementation of the maximum sustainable yield for age-structured fisheries.

    PubMed

    Kanik, Zafer; Kucuksenel, Serkan

    2016-06-01

    One of the main goals stated in the proposals for the Common Fisheries Policy (CFP) reform was achieving maximum sustainable yield (MSY) for all European fisheries. In this paper, we propose a fishing rights allocation mechanism or management system, which specifies catch limits for individual fishing fleets to implement MSY harvesting conditions in an age-structured bioeconomic model. An age-structured model in a single species fishery with two fleets having perfect or imperfect fishing selectivity is studied. If fishing technology or gear selectivity depends on the relative age composition of the mature fish stock, fixed harvest proportions, derived from catchability and bycatch coefficients, is not valid anymore. As a result, not only the age-structure and fishing technology but also the estimated level of MSY is steering the allocation of quota shares. The results also show that allocation of quota shares based on historical catches or auctioning may not provide viable solutions to achieve MSY. PMID:27018447

  15. Quota implementation of the maximum sustainable yield for age-structured fisheries.

    PubMed

    Kanik, Zafer; Kucuksenel, Serkan

    2016-06-01

    One of the main goals stated in the proposals for the Common Fisheries Policy (CFP) reform was achieving maximum sustainable yield (MSY) for all European fisheries. In this paper, we propose a fishing rights allocation mechanism or management system, which specifies catch limits for individual fishing fleets to implement MSY harvesting conditions in an age-structured bioeconomic model. An age-structured model in a single species fishery with two fleets having perfect or imperfect fishing selectivity is studied. If fishing technology or gear selectivity depends on the relative age composition of the mature fish stock, fixed harvest proportions, derived from catchability and bycatch coefficients, is not valid anymore. As a result, not only the age-structure and fishing technology but also the estimated level of MSY is steering the allocation of quota shares. The results also show that allocation of quota shares based on historical catches or auctioning may not provide viable solutions to achieve MSY.

  16. Effects of age and sex on the structural, chemical and technological characteristics of mule duck meat.

    PubMed

    Baeza, E; Salichon, M R; Marche, G; Wacrenier, N; Dominguez, B; Culioli, J

    2000-07-01

    1. The aim of the study was to analyse the effect of age and sex on the chemical, structural and technological characteristics of mule duck meat. 2. Ten males and 10 females were weighed and slaughtered at 8, 10, 11, 12 and 13 weeks of age. Weight, pH value, colour, tenderness and juice loss of breast muscle were determined. 3. The activities of 3 enzymes (citrate synthase, beta-hydroxyacyl CoA dehydrogenase, lactate dehydrogenase) which indicate muscular metabolic activity were assayed. 4. Chemical composition (moisture, lipids, proteins, minerals, lipid and phospholipid classes, fatty acid composition) of breast muscle was analysed. 5. Fibre type, fibre type percentage and cross-sectional areas were determined using histochemistry and an image analysis system. 6. For growth performance and muscular structure, the ideal slaughter age of mule ducks is 10 weeks of age. Chemical and technological analysis indicated that muscular maturity in Pectoralis major was reached at 11 weeks of age, but, at this age, breast lipid content is high. Moreover, after 10 weeks of age, food costs rapidly increased. 7. Lastly, sexual dimorphism for body weight is minor. In this study, at any given age, no significant differences between males and females were shown. Thus, it is possible to rear both sexes together and to slaughter them at the same age.

  17. Structural Validity of the Movement ABC-2 Test: Factor Structure Comparisons across Three Age Groups

    ERIC Educational Resources Information Center

    Schulz, Joerg; Henderson, Sheila E.; Sugden, David A.; Barnett, Anna L.

    2011-01-01

    Background: The Movement ABC test is one of the most widely used assessments in the field of Developmental Coordination Disorder (DCD). Improvements to the 2nd edition of the test (M-ABC-2) include an extension of the age range and reduction in the number of age bands as well as revision of tasks. The total test score provides a measure of motor…

  18. Structural Validity of the Professional Development Profile of the LoTi Digital-Age Survey

    ERIC Educational Resources Information Center

    Mehta, Vandhana; Hull, Darrell M.

    2013-01-01

    The present study was used to examine the structural construct validity of the Professional Development Profile of the LoTi Digital-Age Survey, a measure of teacher instructional practices with technology in the classroom. Teacher responses ("N" = 2,840) from across the United States were used to assess factor structure of the instrument using…

  19. Planting increases the abundance and structure complexity of soil core functional genes relevant to carbon and nitrogen cycling

    PubMed Central

    Wang, Feng; Liang, Yuting; Jiang, Yuji; Yang, Yunfeng; Xue, Kai; Xiong, Jinbo; Zhou, Jizhong; Sun, Bo

    2015-01-01

    Plants have an important impact on soil microbial communities and their functions. However, how plants determine the microbial composition and network interactions is still poorly understood. During a four-year field experiment, we investigated the functional gene composition of three types of soils (Phaeozem, Cambisols and Acrisol) under maize planting and bare fallow regimes located in cold temperate, warm temperate and subtropical regions, respectively. The core genes were identified using high-throughput functional gene microarray (GeoChip 3.0), and functional molecular ecological networks (fMENs) were subsequently developed with the random matrix theory (RMT)-based conceptual framework. Our results demonstrated that planting significantly (P < 0.05) increased the gene alpha-diversity in terms of richness and Shannon – Simpson’s indexes for all three types of soils and 83.5% of microbial alpha-diversity can be explained by the plant factor. Moreover, planting had significant impacts on the microbial community structure and the network interactions of the microbial communities. The calculated network complexity was higher under maize planting than under bare fallow regimes. The increase of the functional genes led to an increase in both soil respiration and nitrification potential with maize planting, indicating that changes in the soil microbial communities and network interactions influenced ecological functioning. PMID:26396042

  20. Planting increases the abundance and structure complexity of soil core functional genes relevant to carbon and nitrogen cycling.

    PubMed

    Wang, Feng; Liang, Yuting; Jiang, Yuji; Yang, Yunfeng; Xue, Kai; Xiong, Jinbo; Zhou, Jizhong; Sun, Bo

    2015-09-23

    Plants have an important impact on soil microbial communities and their functions. However, how plants determine the microbial composition and network interactions is still poorly understood. During a four-year field experiment, we investigated the functional gene composition of three types of soils (Phaeozem, Cambisols and Acrisol) under maize planting and bare fallow regimes located in cold temperate, warm temperate and subtropical regions, respectively. The core genes were identified using high-throughput functional gene microarray (GeoChip 3.0), and functional molecular ecological networks (fMENs) were subsequently developed with the random matrix theory (RMT)-based conceptual framework. Our results demonstrated that planting significantly (P < 0.05) increased the gene alpha-diversity in terms of richness and Shannon - Simpson's indexes for all three types of soils and 83.5% of microbial alpha-diversity can be explained by the plant factor. Moreover, planting had significant impacts on the microbial community structure and the network interactions of the microbial communities. The calculated network complexity was higher under maize planting than under bare fallow regimes. The increase of the functional genes led to an increase in both soil respiration and nitrification potential with maize planting, indicating that changes in the soil microbial communities and network interactions influenced ecological functioning.

  1. Planting increases the abundance and structure complexity of soil core functional genes relevant to carbon and nitrogen cycling

    NASA Astrophysics Data System (ADS)

    Wang, Feng; Liang, Yuting; Jiang, Yuji; Yang, Yunfeng; Xue, Kai; Xiong, Jinbo; Zhou, Jizhong; Sun, Bo

    2015-09-01

    Plants have an important impact on soil microbial communities and their functions. However, how plants determine the microbial composition and network interactions is still poorly understood. During a four-year field experiment, we investigated the functional gene composition of three types of soils (Phaeozem, Cambisols and Acrisol) under maize planting and bare fallow regimes located in cold temperate, warm temperate and subtropical regions, respectively. The core genes were identified using high-throughput functional gene microarray (GeoChip 3.0), and functional molecular ecological networks (fMENs) were subsequently developed with the random matrix theory (RMT)-based conceptual framework. Our results demonstrated that planting significantly (P < 0.05) increased the gene alpha-diversity in terms of richness and Shannon - Simpson’s indexes for all three types of soils and 83.5% of microbial alpha-diversity can be explained by the plant factor. Moreover, planting had significant impacts on the microbial community structure and the network interactions of the microbial communities. The calculated network complexity was higher under maize planting than under bare fallow regimes. The increase of the functional genes led to an increase in both soil respiration and nitrification potential with maize planting, indicating that changes in the soil microbial communities and network interactions influenced ecological functioning.

  2. Spatial and temporal variations in the age structure of Arctic sea ice

    USGS Publications Warehouse

    Belchansky, G.I.; Douglas, D.C.; Platonov, N.G.

    2005-01-01

    Spatial and temporal variations in the age structure of Arctic sea ice are investigated using a new reverse chronology algorithm that tracks ice-covered pixels to their location and date of origin based on ice motion and concentration data. The Beaufort Gyre tends to harbor the oldest (>10 years old) sea ice in the western Arctic while direct ice advection pathways toward the Transpolar Drift Stream maintain relatively young (10 years old (10+ year age class) were observed during 1989-2003. Since the mid-1990s, losses to the 10+ year age class lacked compensation by recruitment due to a prior depletion of all mature (6-10 year) age classes. Survival of the 1994 and 1996-1998 sea ice generations reestablished most mature age classes, and thereby the potential to increase extent of the 10+ year age class during the mid-2000s.

  3. Protection of rubbers against aging with the use of structural, diffusion and kinetic effects

    SciTech Connect

    Kablov, V. F.; Zaikov, G. E.

    2014-05-15

    Processes of rubber aging in the different kinetic modes and mathematical models of the processes including aging and destruction processes under extreme conditions have been studied. The aging process for rubbers as thermodynamically open nonlinear systems has also been considered in the paper. It has been revealed that the aging process can be controlled by the internal physical-chemical processes organization and by creation of external influences (by organization of thermodynamic forces and flows). According to the Onsager principle, in certain conditions of aging the conjugation of thermodynamic forces and flows is possible. The diffusion and structural aspects of aging in elastomeric rubbers and articles thereof have been considered. The composite antiaging systems of prolonged action based on the use of microparticles with a saturated solution of the antiagers migrating into an elastomeric matrix at the exploitation have been proposed.

  4. Protection of rubbers against aging with the use of structural, diffusion and kinetic effects

    NASA Astrophysics Data System (ADS)

    Kablov, V. F.; Zaikov, G. E.

    2014-05-01

    Processes of rubber aging in the different kinetic modes and mathematical models of the processes including aging and destruction processes under extreme conditions have been studied. The aging process for rubbers as thermodynamically open nonlinear systems has also been considered in the paper. It has been revealed that the aging process can be controlled by the internal physical-chemical processes organization and by creation of external influences (by organization of thermodynamic forces and flows). According to the Onsager principle, in certain conditions of aging the conjugation of thermodynamic forces and flows is possible. The diffusion and structural aspects of aging in elastomeric rubbers and articles thereof have been considered. The composite antiaging systems of prolonged action based on the use of microparticles with a saturated solution of the antiagers migrating into an elastomeric matrix at the exploitation have been proposed.

  5. Extended Aging Theories for Predictions of Safe Operational Life of Critical Airborne Structural Components

    NASA Technical Reports Server (NTRS)

    Ko, William L.; Chen, Tony

    2006-01-01

    The previously developed Ko closed-form aging theory has been reformulated into a more compact mathematical form for easier application. A new equivalent loading theory and empirical loading theories have also been developed and incorporated into the revised Ko aging theory for the prediction of a safe operational life of airborne failure-critical structural components. The new set of aging and loading theories were applied to predict the safe number of flights for the B-52B aircraft to carry a launch vehicle, the structural life of critical components consumed by load excursion to proof load value, and the ground-sitting life of B-52B pylon failure-critical structural components. A special life prediction method was developed for the preflight predictions of operational life of failure-critical structural components of the B-52H pylon system, for which no flight data are available.

  6. Ground-based near-infrared observations of the Venus nightside: The thermal structure and water abundance near the surface

    NASA Astrophysics Data System (ADS)

    Meadows, V. S.; Crisp, D.

    We used ground-based near-infrared (NIR) observations of thermal emission from the Venus nightside to determine the temperature structure and water vapor distribution between the surface and the 6-km level. We show that emission from spectral windows near 1.0, 1.1, and 1.18 μm originates primarily from the surface and lowest scale height (~16 km). These windows include absorption by weak H2O and CO2 lines and by the far wings of lines in strong nearby CO2 bands. Rayleigh scattering by the 90-bar CO2 atmosphere and Mie scattering by the H2SO4 clouds attenuate this emission, but add little to its spectral dependence. Surface topography also modulates this NIR thermal emission because high-elevation regions are substantially cooler and emit less thermal radiation than the surrounding plains. These contributions to the emission are clearly resolved in moderate-resolution (λ/Δλ~400) spectral image cubes of the Venus nightside acquired with the infrared imaging spectrometer (IRIS) on the Anglo-Australian Telescope (AAT) in 1991. To analyze these observations, we used a radiative transfer model that includes all of the radiative processes listed above. Synthetic spectra for several topographic elevations were combined with Pioneer Venus altimetry data to generate spatially resolved maps of the NIR thermal emission. Comparisons between these synthetic radiance maps and the IRIS observations indicate no near-infrared signature of the surface emissivity differences seen at microwave wavelengths by the Magellan orbiter. Assuming constant surface emissivity in the near-infrared, we derive nightside averaged temperature lapse rates of -7 to -7.5 K/km in the lowest 6 km. These lapse rates are smaller and indicate much greater static stability than those inferred from earlier measurements and greenhouse models (-8 to -8.5 K/km) [Seiff, 1983]. An acceptable fit to the data was obtained with an H2O mixing ratio profile which increases from 20 ppmv at the cloud base to 45 ppmv

  7. Probing the age and structure of the nearby very young open clusters NGC2244 and 2239

    NASA Astrophysics Data System (ADS)

    Bonatto, C.; Bica, E.

    2009-04-01

    The very young open cluster (OC) NGC2244 in the Rosette Nebula was studied with field-star-decontaminated Two-Micron All-Sky Survey (2MASS) photometry, which shows the main-sequence (MS) stars and an abundant pre-MS (PMS) population. Fundamental and structural parameters were derived with colour-magnitude diagrams (CMDs), stellar radial density profiles (RDPs) and mass functions (MFs). Most previous studies centred NGC2244 close to the bright K0V star 12Monocerotis, which is not a cluster member. Instead, the near-infrared RDP indicates a pronounced core near the O5 star HD46150. We derive an age within 1-6Myr, an absorption AV = 1.7 +/- 0.2, a distance from the Sun dsolar = 1.6 +/- 0.2kpc (~1.5kpc outside the solar circle), an MF slope χ = 0.91 +/- 0.13 and a total (MS+PMS) stellar mass of ~625Msolar. Its RDP is characterized by the core and cluster radii Rc ~ 5.6arcmin (~2.6pc) and RRDP ~ 10arcmin (~4.7pc), respectively. Departure from dynamical equilibrium is suggested by the abnormally large core radius and the marked central stellar excess. We also investigate the elusive neighbouring OC NGC2239, which is low mass (mMS+PMS ~ 301Msolar), young (5 +/- 4Myr) rather absorbed (AV = 3.4 +/- 0.2), and located in the background of NGC2244 at dsolar = 3.9 +/- 0.4kpc. Its RDP follows a King-like function of Rc ~ 0.5arcmin ~ 0.5pc and RRDP ~ 5.0arcmin ~ 5.6pc. The MF slope, χ = 1.24 +/- 0.06, is essentially Salpeter's initial mass function. NGC2244 is probably doomed to dissolution in a few 107yr. Wide-field extractions and field-star decontamination increase the stellar statistics and enhance both CMDs and RDPs, which is essential for faint and bright star clusters.

  8. Evolution of a plastic quantitative trait in an age-structured population in a fluctuating environment.

    PubMed

    Engen, Steinar; Lande, Russell; Saether, Bernt-Erik

    2011-10-01

    We analyze weak fluctuating selection on a quantitative character in an age-structured population not subject to density regulation. We assume that early in the first year of life before selection, during a critical state of development, environments exert a plastic effect on the phenotype, which remains constant throughout the life of an individual. Age-specific selection on the character affects survival and fecundity, which have intermediate optima subject to temporal environmental fluctuations with directional selection in some age classes as special cases. Weighting individuals by their reproductive value, as suggested by Fisher, we show that the expected response per year in the weighted mean character has the same form as for models with no age structure. Environmental stochasticity generates stochastic fluctuations in the weighted mean character following a first-order autoregressive model with a temporally autocorrelated noise term and stationary variance depending on the amount of phenotypic plasticity. The parameters of the process are simple weighted averages of parameters used to describe age-specific survival and fecundity. The "age-specific selective weights" are related to the stable distribution of reproductive values among age classes. This allows partitioning of the change in the weighted mean character into age-specific components.

  9. Late embryogenesis abundant proteins

    PubMed Central

    Olvera-Carrillo, Yadira; Reyes, José Luis

    2011-01-01

    Late Embryogenesis Abundant (LEA) proteins accumulate at the onset of seed desiccation and in response to water deficit in vegetative plant tissues. The typical LEA proteins are highly hydrophilic and intrinsically unstructured. They have been classified in different families, each one showing distinctive conserved motifs. In this manuscript we present and discuss some of the recent findings regarding their role in plant adaptation to water deficit, as well as those concerning to their possible function, and how it can be related to their intrinsic structural flexibility. PMID:21447997

  10. Lithium Abundance in Planet Search Stars

    NASA Astrophysics Data System (ADS)

    Myles, Justin; Yale Exoplanets

    2016-01-01

    Since most lithium in the universe is primordial and is destroyed in stars, lithium abundance can be used as a stellar age indicator. Some research seems to show that planet formation may also affect lithium abundance in exoplanet host stars (EHS). However, small and heterogenous samples have made both of these phenomena unclear. Further study of lithium abundance in EHS is needed to better understand possible physical roles of lithium in planet formation theory. We use a large homogenous sample with accurate stellar parameters on which we will use equivalent width analysis to determine precise lithium abundances. From these abundance values we determine an age vs. abundance relation. Additionally, we aim to explore correlation between lithium abundance and planet formation.

  11. Conformation of a Group 2 Late Embryogenesis Abundant Protein from Soybean. Evidence of Poly (l-Proline)-type II Structure1

    PubMed Central

    Soulages, Jose L.; Kim, Kangmin; Arrese, Estela L.; Walters, Christina; Cushman, John C.

    2003-01-01

    Late embryogenesis abundant (LEA) proteins are members of a large group of hydrophilic, glycine-rich proteins found in plants, algae, fungi, and bacteria known collectively as hydrophilins that are preferentially expressed in response to dehydration or hyperosmotic stress. Group 2 LEA (dehydrins or responsive to abscisic acid) proteins are postulated to stabilize macromolecules against damage by freezing, dehydration, ionic, or osmotic stress. However, the structural and physicochemical properties of group 2 LEA proteins that account for such functions remain unknown. We have analyzed the structural properties of a recombinant form of a soybean (Glycine max) group 2 LEA (rGmDHN1). Differential scanning calorimetry of purified rGmDHN1 demonstrated that the protein does not display a cooperative unfolding transition upon heating. Ultraviolet absorption and circular dichroism spectroscopy revealed that the protein is in a largely hydrated and unstructured conformation in solution. However, ultraviolet absorption and circular dichroism measurements collected at different temperatures showed that the protein exists in equilibrium between two extended conformational states: unordered and left-handed extended helical or poly (l-proline)-type II structures. It is estimated that 27% of the residues of rGmDHN1 adopt or poly (l-proline)-type II-like helical conformation at 12°C. The content of extended helix gradually decreases to 15% as the temperature is increased to 80°C. Studies of the conformation of the protein in solution in the presence of liposomes, trifluoroethanol, and sodium dodecyl sulfate indicated that rGmDHN1 has a very low intrinsic ability to adopt α-helical structure and to interact with phospholipid bilayers through amphipathic α-helices. The ability of the protein to remain in a highly extended conformation at low temperatures could constitute the basis of the functional role of GmDHN1 in the prevention of freezing, desiccation, ionic, or osmotic

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

    NASA Technical Reports Server (NTRS)

    Ko, William L.

    2003-01-01

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

  13. Arterial structure and function in vascular ageing: are you as old as your arteries?

    PubMed

    Thijssen, Dick H J; Carter, Sophie E; Green, Daniel J

    2016-04-15

    Advancing age may be the most potent independent predictor of future cardiovascular events, a relationship that is not fully explained by time-related changes in traditional cardiovascular risk factors. Since some arteries exhibit differential susceptibility to atherosclerosis, generalisations regarding the impact of ageing in humans may be overly simplistic, whereas in vivo assessment of arterial function and health provide direct insight. Coronary and peripheral (conduit, resistance and skin) arteries demonstrate a gradual, age-related impairment in vascular function that is likely to be related to a reduction in endothelium-derived nitric oxide bioavailability and/or increased production of vasoconstrictors (e.g. endothelin-1). Increased exposure and impaired ability for defence mechanisms to resist oxidative stress and inflammation, but also cellular senescence processes, may contribute to age-related changes in vascular function and health. Arteries also undergo structural changes as they age. Gradual thickening of the arterial wall, changes in wall content (i.e. less elastin, advanced glycation end-products) and increase in conduit artery diameter are observed with older age and occur similarly in central and peripheral arteries. These changes in structure have important interactive effects on artery function, with increases in small and large arterial stiffness representing a characteristic change with older age. Importantly, direct measures of arterial function and structure predict future cardiovascular events, independent of age or other cardiovascular risk factors. Taken together, and given the differential susceptibility of arteries to atherosclerosis in humans, direct measurement of arterial function and health may help to distinguish between biological and chronological age-related change in arterial health in humans.

  14. The age and genesis of the structures in the Amerasian basin

    NASA Astrophysics Data System (ADS)

    Verzhbitsky, E. V.; Lobkovsky, L. I.; Kononov, M. V.; Byakov, A. F.

    2012-11-01

    An insufficient number of dated native samples and indistinct magnetic anomalies in the Amerasian Basin prevent geophysicists from identifying the exact age of most of its structural elements. Due to this, it is impossible to gain an insight into the evolution of this vast region, which is highly promising in terms of its hydrocarbon potential. Therefore, the geological time of the formation of the structural elements composing the Amerasian Basin is determined either hypothetically or very loosely (for example, Late Cretaceous-Cenozoic). In order to more precisely estimate the time of formation of the structural elements within the Amerasian Basin, we applied the geothermal method, which is highly informative in terms of the age of the lithosphere, its thickness, and the evolution of the basin structures. Besides, this method provides far narrower time constraints for the formation of the structures compared to the geological data. Based on the thermal flow data, we have numerically calculated the age of the structural elements composing the Amerasian Basin: Podvodnikov Basin (97-79 Ma), Makarov Basin (75-61 Ma), Alpha-Mendeleev Ridge (97-79 Ma), and Lomonosov Ridge (69-57 Ma). The age of these structures derived from the geothermal data agrees with the estimates determined from the geological, geomagnetic, seismic, and radiometric data. Based on the age of the structures estimated from the thermal flow data and the analysis of the geological and geophysical evidence, conclusions are made concerning the genesis and character of formation of the Podvodnikov and Makarov basins and the Alpha-Mendeleev and Lomonosov ridges within the Amerasian Basin.

  15. Relationship of decrease in fecundity with advancing age to structural changes in mouse endometrium

    PubMed Central

    SHIMIZU, KIYOSHI; YAMADA, JINZO

    2000-01-01

    The aim of this study was to determine whether a relationship exists between decrease in fecundity and structural changes in the antimesometrial endometrium of the mouse. Fecundity was calculated as the number of animals showing a placental sign/number of copulated animals ×100 (%). Structural changes in the endometrium were examined by electron microscopy. A negative correlation between age and fecundity was found. Fecundity was 50% at 7 mo of age. At this age, amorphous material appeared in the region between the basement membrane deep to the luminal epithelium and the subepithelial cells. This material was sometimes attached to the basement membrane. It increased in amount with advancing age, as fecundity decreased. The structure of the uterine luminal epithelial cells did not alter with age. The results indicated that decrease in fecundity with advancing age is correlated with the appearance of amorphous material beneath the basal lamina of the endometrial epithelium. It is suggested that this could impair communication between the luminal epithelium and the endometrial stroma, which plays an important role in implantation. PMID:10697293

  16. A kinetic theory for age-structured stochastic birth-death processes

    NASA Astrophysics Data System (ADS)

    Chou, Tom; Greenman, Chris

    Classical age-structured mass-action models such as the McKendrick-von Foerster equation have been extensively studied but they are structurally unable to describe stochastic fluctuations or population-size-dependent birth and death rates. Conversely, current theories that include size-dependent population dynamics (e.g., carrying capacity) cannot be easily extended to take into account age-dependent birth and death rates. In this paper, we present a systematic derivation of a new fully stochastic kinetic theory for interacting age-structured populations. By defining multiparticle probability density functions, we derive a hierarchy of kinetic equations for the stochastic evolution of an aging population undergoing birth and death. We show that the fully stochastic age-dependent birth-death process precludes factorization of the corresponding probability densities, which then must be solved by using a BBGKY-like hierarchy. Our results generalize both deterministic models and existing master equation approaches by providing an intuitive and efficient way to simultaneously model age- and population-dependent stochastic dynamics applicable to the study of demography, stem cell dynamics, and disease evolution. NSF.

  17. Disentangling normal aging from Alzheimer's disease in structural magnetic resonance images.

    PubMed

    Lorenzi, Marco; Pennec, Xavier; Frisoni, Giovanni B; Ayache, Nicholas

    2015-01-01

    The morphology observed in the brains of patients affected by Alzheimer's disease (AD) is a combination of different biological processes, such as normal aging and the pathological matter loss specific to AD. The ability to differentiate between these biological factors is fundamental to reliably evaluate pathological AD-related structural changes, especially in the earliest phase of the disease, at prodromal and preclinical stages. Here we propose a method based on non-linear image registration to estimate and analyze from observed brain morphologies the relative contributions from aging and pathology. In particular, we first define a longitudinal model of the brain's normal aging process from serial T1-weight magnetic resonance imaging scans of 65 healthy participants. The longitudinal model is then used as a reference for the cross-sectional analysis. Given a new brain image, we then estimate its anatomical age relative to the aging model; this is defined as a morphological age shift with respect to the average age of the healthy population at baseline. Finally, we define the specific morphological process as the remainder of the observed anatomy after the removal of the estimated normal aging process. Experimental results from 105 healthy participants, 110 subjects with mild cognitive impairment (MCI), 86 with MCI converted to AD, and 134 AD patients provide a novel description of the anatomical changes observed across the AD time span: normal aging, normal aging at risk, conversion to MCI, and the latest stages of AD. More advanced AD stages are associated with an increased morphological age shift in the brain and with strong disease-specific morphological changes affecting mainly ventricles, temporal poles, the entorhinal cortex, and hippocampi. Our model shows that AD is characterized by localized disease-specific brain changes as well as by an accelerated global aging process. This method may thus represent a more precise instrument to identify potential

  18. The relationship between health expenditures and the age structure of the population in OECD countries.

    PubMed

    O'Connell, J M

    1996-01-01

    The purpose of this study was to analyse national health expenditures of OECD countries relative to their age structures. Using econometric techniques designed to analyse cross-sectional time series data, the ageing of the population was found to affect health spending in several countries while having no effect in others. In addition, the effect of income on health spending was lower than that generally reported in the literature. These findings suggest that unobserved country-specific factors play a major role in determining the amount of resources allocated to health services in a country. Such factors also determine if the ageing of the population with increased health spending.

  19. The abundance of functional genes, cbbL, nifH, amoA and apsA, and bacterial community structure of intertidal soil from Arabian Sea.

    PubMed

    Keshri, Jitendra; Yousuf, Basit; Mishra, Avinash; Jha, Bhavanath

    2015-06-01

    The Gulf of Cambay is a trumpet-shaped inlet of the Arabian Sea, located along the west coast of India and confronts a high tidal range with strong water currents. The region belongs to a semi-arid zone and saline alkaline intertidal soils are considered biologically extreme. The selected four soil types (S1-S4) were affected by salinity, alkalinity and sodicity. Soil salinity ranged from 20 to 126 dS/m, soil pH 8.6-10.0 with high sodium adsorption ratio (SAR) and exchangeable sodium percentage (ESP). Abundance of the key functional genes like cbbL, nifH, amoA and apsA involved in biogeochemical cycling were targeted using qPCR, which varied from (2.36 ± 0.03) × 10(4) to (2.87 ± 0.26) × 10(8), (1.18 ± 0.28) × 10(6) to (1.01 ± 0.26) × 10(9), (1.41 ± 0.21) × 10(6) to (1.29 ± 0.05) × 10(8) and (8.47 ± 0.23) × 10(4) to (1.73 ± 0.01) × 10(6) per gram dry weight, respectively. The microbial community structure revealed that soils S1 and S3 were dominated by phylum Firmicutes whereas S4 and S2 showed an abundance of Proteobacterial clones. These soils also represented Bacteroidetes, Chloroflexi, Actinobacteria, Planctomycetes and Acidobacteria clones. Molecular phylogeny showed a significant variation in the bacterial community distribution among the intertidal soil types. A high number of novel taxonomic units were observed which makes the intertidal zone a unique reservoir of unidentified bacterial taxa that may be explored further.

  20. The abundance of functional genes, cbbL, nifH, amoA and apsA, and bacterial community structure of intertidal soil from Arabian Sea.

    PubMed

    Keshri, Jitendra; Yousuf, Basit; Mishra, Avinash; Jha, Bhavanath

    2015-06-01

    The Gulf of Cambay is a trumpet-shaped inlet of the Arabian Sea, located along the west coast of India and confronts a high tidal range with strong water currents. The region belongs to a semi-arid zone and saline alkaline intertidal soils are considered biologically extreme. The selected four soil types (S1-S4) were affected by salinity, alkalinity and sodicity. Soil salinity ranged from 20 to 126 dS/m, soil pH 8.6-10.0 with high sodium adsorption ratio (SAR) and exchangeable sodium percentage (ESP). Abundance of the key functional genes like cbbL, nifH, amoA and apsA involved in biogeochemical cycling were targeted using qPCR, which varied from (2.36 ± 0.03) × 10(4) to (2.87 ± 0.26) × 10(8), (1.18 ± 0.28) × 10(6) to (1.01 ± 0.26) × 10(9), (1.41 ± 0.21) × 10(6) to (1.29 ± 0.05) × 10(8) and (8.47 ± 0.23) × 10(4) to (1.73 ± 0.01) × 10(6) per gram dry weight, respectively. The microbial community structure revealed that soils S1 and S3 were dominated by phylum Firmicutes whereas S4 and S2 showed an abundance of Proteobacterial clones. These soils also represented Bacteroidetes, Chloroflexi, Actinobacteria, Planctomycetes and Acidobacteria clones. Molecular phylogeny showed a significant variation in the bacterial community distribution among the intertidal soil types. A high number of novel taxonomic units were observed which makes the intertidal zone a unique reservoir of unidentified bacterial taxa that may be explored further. PMID:25862282

  1. Effects of winter burning and structural marsh management on vegetation and winter bird abundance in the Gulf Coast Chenier Plain, USA

    USGS Publications Warehouse

    Gabrey, S.W.; Afton, A.D.; Wilson, B.C.

    1999-01-01

    Marshes in the Gulf Coast Chenier Plain provide important winter habitats for many species of birds. Many of these marshes are managed intensively through a combination of fall/winter burning and construction of impoundments to improve wintering waterfowl habitat, reduce wetland loss, and create emergent wetlands. Little information is available on effects of this management on wintering birds, particularly passerines. We conducted experimental burns in impounded and unimpounded marshes on Rockefeller State Wildlife Refuge in southwest Louisiana and recorded species composition and abundance of birds during the 1996 and 1997 winters. We found that burning and impoundment influenced vegetation structure, which in turn influenced bird abundance and species composition. Blackbirds (Icteridae) preferred recently burned plots. Sparrows (Emberizidae) and wrens (Troglodytidae) avoided recently burned plots but recolonized these plots after one year of vegetation recovery. Sparrows and wrens present in burned plots during the first winter following burning generally were observed in scattered patches of unburned vegetation. Suitability of Chenier Plain marshes as winter habitat for several bird species was reduced during the winter in which burning was conducted, particularly if a high proportion of the plot was burned. We recommend that patchy burns be used, at both the landscape level and within specific burned areas, to achieve management objectives and still provide suitable winter habitat for non-target species. Although many groups of birds depend on Chenier Plain marshes for winter habitat, these groups differ in their specific habitat requirements. We recommend that a diverse wetland complex (e.g., impoundments managed for waterfowl foraging habitat interpersed with those managed for passerine winter cover) be maintained.

  2. Key Plant Structural and Allocation Traits Depend on Relative Age in the Perennial Herb Pimpinella saxifraga

    PubMed Central

    NIINEMETS, ÜLO

    2005-01-01

    • Background and Aims Perennial plant formations always include a mixture of various-aged individuals of community-creating species, but the physiological and competitive potentials of plants of differing age and the importance on whole community functioning are still not entirely known. The current study tested the hypothesis that ontogenetically old plants have limited biomass investments in leaves and enhanced foliage support costs. • Methods Leaf structure, size and biomass allocation were studied in the perennial herb Pimpinella saxifraga during plant ontogeny from seedling to senile phases to determine age-dependent controls on key plant structural traits. The average duration of the full ontogenetic cycle is approx. 5–10 years in this species. Plants were sampled from shaded and open habitats. • Key Results Leaflet dry mass per unit area (MA) increased, and the fraction of plant biomass in leaflets (FL) decreased with increasing age, leading to a 5- to 11-fold decrease in leaf area ratio (LAR = FL/MA) between seedlings and senescent plants. In contrast, the fraction of below-ground biomass increased with increasing age. Leaflet size and number per leaf increased with increasing age. This was not associated with enhanced support cost in older plants as age-dependent changes in leaf shape and increased foliage packing along the rachis compensated for an overall increase in leaf size. Age-dependent trends were the same in habitats with various irradiance, but the LAR of plants of varying age was approx. 1·5-fold larger in the shade due to lower MA and larger FL. • Conclusions As plant light interception per unit total plant mass scales with LAR, these data demonstrate major age-dependent differences in plant light-harvesting efficiency that are further modified by site light availability. These ontogenetic changes reduce the differences among co-existing species in perennial communities, and therefore need consideration in our understanding of how

  3. Structural architecture supports functional organization in the human aging brain at a regionwise and network level.

    PubMed

    Zimmermann, Joelle; Ritter, Petra; Shen, Kelly; Rothmeier, Simon; Schirner, Michael; McIntosh, Anthony R

    2016-07-01

    Functional interactions in the brain are constrained by the underlying anatomical architecture, and structural and functional networks share network features such as modularity. Accordingly, age-related changes of structural connectivity (SC) may be paralleled by changes in functional connectivity (FC). We provide a detailed qualitative and quantitative characterization of the SC-FC coupling in human aging as inferred from resting-state blood oxygen-level dependent functional magnetic resonance imaging and diffusion-weighted imaging in a sample of 47 adults with an age range of 18-82. We revealed that SC and FC decrease with age across most parts of the brain and there is a distinct age-dependency of regionwise SC-FC coupling and network-level SC-FC relations. A specific pattern of SC-FC coupling predicts age more reliably than does regionwise SC or FC alone (r = 0.73, 95% CI = [0.7093, 0.8522]). Hence, our data propose that regionwise SC-FC coupling can be used to characterize brain changes in aging. Hum Brain Mapp 37:2645-2661, 2016. © 2016 Wiley Periodicals, Inc. PMID:27041212

  4. Structural transition in sputter-deposited amorphous germanium films by aging at ambient temperature

    NASA Astrophysics Data System (ADS)

    Okugawa, M.; Nakamura, R.; Ishimaru, M.; Watanabe, K.; Yasuda, H.; Numakura, H.

    2016-06-01

    The structure of amorphous Ge (a-Ge) films prepared by sputter-deposition and the effects of aging at ambient temperature and pressure were studied by pair-distribution-function (PDF) analysis from electron scattering and molecular dynamics simulations. The PDFs of the as-deposited and aged samples for 3-13 months showed that the major peaks for Ge-Ge bonds decrease in intensity and broaden with aging for up to 7 months. In the PDFs of a-Ge of molecular dynamics simulation obtained by quenching liquid at different rates, the major peak intensities of a slowly cooled model are higher than those of a rapidly cooled model. Analyses on short- and medium-range configurations show that the slowly cooled model includes a certain amount of medium-range ordered (MRO) clusters, while the rapidly cooled model includes liquid-like configurations rather than MRO clusters. The similarity between experimental and computational PDFs implies that as-deposited films are similar in structure to the slowly cooled model, whereas the fully aged films are similar to the rapidly cooled model. It is assumed that as they undergo room-temperature aging, the MRO clusters disintegrate and transform into liquid-like regions in the same matrix. This transition in local configurations is discussed in terms of instability and the non-equilibrium of nanoclusters produced by a vapor-deposition process.

  5. A Group 6 Late Embryogenesis Abundant Protein from Common Bean Is a Disordered Protein with Extended Helical Structure and Oligomer-forming Properties*

    PubMed Central

    Rivera-Najera, Lucero Y.; Saab-Rincón, Gloria; Battaglia, Marina; Amero, Carlos; Pulido, Nancy O.; García-Hernández, Enrique; Solórzano, Rosa M.; Reyes, José L.; Covarrubias, Alejandra A.

    2014-01-01

    Late embryogenesis-abundant proteins accumulate to high levels in dry seeds. Some of them also accumulate in response to water deficit in vegetative tissues, which leads to a remarkable association between their presence and low water availability conditions. A major sub-group of these proteins, also known as typical LEA proteins, shows high hydrophilicity and a high percentage of glycine and other small amino acid residues, distinctive physicochemical properties that predict a high content of structural disorder. Although all typical LEA proteins share these characteristics, seven groups can be distinguished by sequence similarity, indicating structural and functional diversity among them. Some of these groups have been extensively studied; however, others require a more detailed analysis to advance in their functional understanding. In this work, we report the structural characterization of a group 6 LEA protein from a common bean (Phaseolus vulgaris L.) (PvLEA6) by circular dichroism and nuclear magnetic resonance showing that it is a disordered protein in aqueous solution. Using the same techniques, we show that despite its unstructured nature, the addition of trifluoroethanol exhibited an intrinsic potential in this protein to gain helicity. This property was also promoted by high osmotic potentials or molecular crowding. Furthermore, we demonstrate that PvLEA6 protein is able to form soluble homo-oligomeric complexes that also show high levels of structural disorder. The association between PvLEA6 monomers to form dimers was shown to occur in plant cells by bimolecular fluorescence complementation, pointing to the in vivo functional relevance of this association. PMID:25271167

  6. A group 6 late embryogenesis abundant protein from common bean is a disordered protein with extended helical structure and oligomer-forming properties.

    PubMed

    Rivera-Najera, Lucero Y; Saab-Rincón, Gloria; Battaglia, Marina; Amero, Carlos; Pulido, Nancy O; García-Hernández, Enrique; Solórzano, Rosa M; Reyes, José L; Covarrubias, Alejandra A

    2014-11-14

    Late embryogenesis-abundant proteins accumulate to high levels in dry seeds. Some of them also accumulate in response to water deficit in vegetative tissues, which leads to a remarkable association between their presence and low water availability conditions. A major sub-group of these proteins, also known as typical LEA proteins, shows high hydrophilicity and a high percentage of glycine and other small amino acid residues, distinctive physicochemical properties that predict a high content of structural disorder. Although all typical LEA proteins share these characteristics, seven groups can be distinguished by sequence similarity, indicating structural and functional diversity among them. Some of these groups have been extensively studied; however, others require a more detailed analysis to advance in their functional understanding. In this work, we report the structural characterization of a group 6 LEA protein from a common bean (Phaseolus vulgaris L.) (PvLEA6) by circular dichroism and nuclear magnetic resonance showing that it is a disordered protein in aqueous solution. Using the same techniques, we show that despite its unstructured nature, the addition of trifluoroethanol exhibited an intrinsic potential in this protein to gain helicity. This property was also promoted by high osmotic potentials or molecular crowding. Furthermore, we demonstrate that PvLEA6 protein is able to form soluble homo-oligomeric complexes that also show high levels of structural disorder. The association between PvLEA6 monomers to form dimers was shown to occur in plant cells by bimolecular fluorescence complementation, pointing to the in vivo functional relevance of this association. PMID:25271167

  7. Structure and composition of arytenoid cartilage of the bullfrog (Lithobates catesbeianus) during maturation and aging.

    PubMed

    Laureano, Priscila Eliane dos Santos; Oliveira, Kris Daiana Silva; de Aro, Andrea Aparecida; Gomes, Laurecir; Pimentel, Edson Rosa; Esquisatto, Marcelo Augusto Marretto

    2015-10-01

    The aging process induces progressive and irreversible changes in the structural and functional organization of animals. The objective of this study was to evaluate the effects of aging on the structure and composition of the extracellular matrix of the arytenoid cartilage found in the larynx of male bullfrogs (Lithobates catesbeianus) kept in captivity for commercial purposes. Animals at 7, 180 and 1080 days post-metamorphosis (n=10/age) were euthanized and the cartilage was removed and processed for structural and biochemical analysis. For the structural analyses, cartilage sections were stained with picrosirius, toluidine blue, Weigert's resorcin-fuchsin and Von Kossa stain. The sections were also submitted to immunohistochemistry for detection of collagen types I and II. Other samples were processed for the ultrastructural and cytochemical analysis of proteoglycans. Histological sections were used to chondrocyte count. The number of positive stainings for proteoglycans was quantified by ultrastructural analysis. For quantification and analysis of glycosaminoglycans were used the dimethyl methylene blue and agarose gel electrophoresis methods. The chloramine T method was used for hydroxyproline quantification. At 7 days, basophilia was observed in the pericellular and territorial matrix, which decreased in the latter over the period studied. Collagen fibers were arranged perpendicular to the major axis of the cartilaginous plate and were thicker in older animals. Few calcification areas were observed at the periphery of the cartilage specimens in 1080-day-old animals. Type II collagen was present throughout the stroma at the different ages. Elastic fibers were found in the stroma and perichondrium and increased with age in the two regions. Proteoglycan staining significantly increased from 7 to 180 days and reduced at 1080 days. The amount of total glycosaminoglycans was higher in 180-day-old animals compared to the other ages, with marked presence of

  8. Interactive effects of stress and aging on structural plasticity in the prefrontal cortex

    PubMed Central

    Bloss, Erik B.; Janssen, William G.; McEwen, Bruce S.; Morrison, John H.

    2010-01-01

    Neuronal networks in the prefrontal cortex mediate the highest levels of cognitive processing and decision making, and the capacity to perform these functions is among the cognitive features most vulnerable to aging. Despite much research, the neurobiological basis of age-related compromised prefrontal function remains elusive. Many investigators have hypothesized that exposure to stress may accelerate cognitive aging, though few studies have directly tested this hypothesis and even fewer have investigated a neuronal basis for such effects. It is known that in young animals, stress causes morphological remodeling of prefrontal pyramidal neurons that is reversible. The present studies sought to determine whether age influences the reversibility of stress-induced morphological plasticity in rat prefrontal neurons. We hypothesized that neocortical structural resilience is compromised in normal aging. To directly test this hypothesis we utilized a well-characterized chronic restraint stress paradigm, with an additional group allowed to recover from the stress paradigm, in 3, 12 and 20-month old male rats. In young animals, stress induced reductions of apical dendritic length and branch number, which were reversed with recovery; in contrast, middle-aged and aged rats failed to show reversible morphological remodeling when subjected to the same stress and recovery paradigm. The data presented here provide evidence that aging is accompanied by selective impairments in long-term neocortical morphological plasticity. PMID:20463234

  9. Aging Optimization of Aluminum-Lithium Alloy L277 for Application to Cryotank Structures

    NASA Technical Reports Server (NTRS)

    Sova, B. J.; Sankaran, K. K.; Babel, H.; Farahmand, B.; Cho, A.

    2003-01-01

    Compared with aluminum alloys such as 2219, which is widely used in space vehicle for cryogenic tanks and unpressurized structures, aluminum-lithium alloys possess attractive combinations of lower density and higher modulus along with comparable mechanical properties and improved damage tolerance. These characteristics have resulted in the successful use of the aluminum-lithium alloy 2195 for the Space Shuttle External Tank, and the consideration of newer U.S. aluminum-lithium alloys such as L277 and C458 for future space vehicles. A design of experiments aging study was conducted for plate and a limited study on extrusions. To achieve the T8 temper, Alloy L277 is typically aged at 290 F for 40 hours. In the study for plate, a two-step aging treatment was developed through a design of experiments study and the one step aging used as a control. Based on the earlier NASA studies on 2195, the first step aging temperature was varied between 220 F and 260 F. The second step aging temperatures was varied between 290 F and 310 F, which is in the range of the single-step aging temperature. For extrusions, two, single-step, and one two-step aging condition were evaluated. The results of the design of experiments used for the T8 temper as well as a smaller set of experiments for the T6 temper for plate and the results for extrusions will be presented.

  10. 11β-Hydroxysteroid dehydrogenase blockade prevents age-induced skin structure and function defects.

    PubMed

    Tiganescu, Ana; Tahrani, Abd A; Morgan, Stuart A; Otranto, Marcela; Desmoulière, Alexis; Abrahams, Lianne; Hassan-Smith, Zaki; Walker, Elizabeth A; Rabbitt, Elizabeth H; Cooper, Mark S; Amrein, Kurt; Lavery, Gareth G; Stewart, Paul M

    2013-07-01

    Glucocorticoid (GC) excess adversely affects skin integrity, inducing thinning and impaired wound healing. Aged skin, particularly that which has been photo-exposed, shares a similar phenotype. Previously, we demonstrated age-induced expression of the GC-activating enzyme 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) in cultured human dermal fibroblasts (HDFs). Here, we determined 11β-HSD1 levels in human skin biopsies from young and older volunteers and examined the aged 11β-HSD1 KO mouse skin phenotype. 11β-HSD1 activity was elevated in aged human and mouse skin and in PE compared with donor-matched photo-protected human biopsies. Age-induced dermal atrophy with deranged collagen structural organization was prevented in 11β-HSD1 KO mice, which also exhibited increased collagen density. We found that treatment of HDFs with physiological concentrations of cortisol inhibited rate-limiting steps in collagen biosynthesis and processing. Furthermore, topical 11β-HSD1 inhibitor treatment accelerated healing of full-thickness mouse dorsal wounds, with improved healing also observed in aged 11β-HSD1 KO mice. These findings suggest that elevated 11β-HSD1 activity in aging skin leads to increased local GC generation, which may account for adverse changes occurring in the elderly, and 11β-HSD1 inhibitors may be useful in the treatment of age-associated impairments in dermal integrity and wound healing.

  11. Kinetic theory of age-structured stochastic birth-death processes.

    PubMed

    Greenman, Chris D; Chou, Tom

    2016-01-01

    Classical age-structured mass-action models such as the McKendrick-von Foerster equation have been extensively studied but are unable to describe stochastic fluctuations or population-size-dependent birth and death rates. Stochastic theories that treat semi-Markov age-dependent processes using, e.g., the Bellman-Harris equation do not resolve a population's age structure and are unable to quantify population-size dependencies. Conversely, current theories that include size-dependent population dynamics (e.g., mathematical models that include carrying capacity such as the logistic equation) cannot be easily extended to take into account age-dependent birth and death rates. In this paper, we present a systematic derivation of a new, fully stochastic kinetic theory for interacting age-structured populations. By defining multiparticle probability density functions, we derive a hierarchy of kinetic equations for the stochastic evolution of an aging population undergoing birth and death. We show that the fully stochastic age-dependent birth-death process precludes factorization of the corresponding probability densities, which then must be solved by using a Bogoliubov--Born--Green--Kirkwood--Yvon-like hierarchy. Explicit solutions are derived in three limits: no birth, no death, and steady state. These are then compared with their corresponding mean-field results. Our results generalize both deterministic models and existing master equation approaches by providing an intuitive and efficient way to simultaneously model age- and population-dependent stochastic dynamics applicable to the study of demography, stem cell dynamics, and disease evolution.

  12. Kinetic theory of age-structured stochastic birth-death processes

    NASA Astrophysics Data System (ADS)

    Greenman, Chris D.; Chou, Tom

    2016-01-01

    Classical age-structured mass-action models such as the McKendrick-von Foerster equation have been extensively studied but are unable to describe stochastic fluctuations or population-size-dependent birth and death rates. Stochastic theories that treat semi-Markov age-dependent processes using, e.g., the Bellman-Harris equation do not resolve a population's age structure and are unable to quantify population-size dependencies. Conversely, current theories that include size-dependent population dynamics (e.g., mathematical models that include carrying capacity such as the logistic equation) cannot be easily extended to take into account age-dependent birth and death rates. In this paper, we present a systematic derivation of a new, fully stochastic kinetic theory for interacting age-structured populations. By defining multiparticle probability density functions, we derive a hierarchy of kinetic equations for the stochastic evolution of an aging population undergoing birth and death. We show that the fully stochastic age-dependent birth-death process precludes factorization of the corresponding probability densities, which then must be solved by using a Bogoliubov--Born--Green--Kirkwood--Yvon-like hierarchy. Explicit solutions are derived in three limits: no birth, no death, and steady state. These are then compared with their corresponding mean-field results. Our results generalize both deterministic models and existing master equation approaches by providing an intuitive and efficient way to simultaneously model age- and population-dependent stochastic dynamics applicable to the study of demography, stem cell dynamics, and disease evolution.

  13. Kinetic theory of age-structured stochastic birth-death processes.

    PubMed

    Greenman, Chris D; Chou, Tom

    2016-01-01

    Classical age-structured mass-action models such as the McKendrick-von Foerster equation have been extensively studied but are unable to describe stochastic fluctuations or population-size-dependent birth and death rates. Stochastic theories that treat semi-Markov age-dependent processes using, e.g., the Bellman-Harris equation do not resolve a population's age structure and are unable to quantify population-size dependencies. Conversely, current theories that include size-dependent population dynamics (e.g., mathematical models that include carrying capacity such as the logistic equation) cannot be easily extended to take into account age-dependent birth and death rates. In this paper, we present a systematic derivation of a new, fully stochastic kinetic theory for interacting age-structured populations. By defining multiparticle probability density functions, we derive a hierarchy of kinetic equations for the stochastic evolution of an aging population undergoing birth and death. We show that the fully stochastic age-dependent birth-death process precludes factorization of the corresponding probability densities, which then must be solved by using a Bogoliubov--Born--Green--Kirkwood--Yvon-like hierarchy. Explicit solutions are derived in three limits: no birth, no death, and steady state. These are then compared with their corresponding mean-field results. Our results generalize both deterministic models and existing master equation approaches by providing an intuitive and efficient way to simultaneously model age- and population-dependent stochastic dynamics applicable to the study of demography, stem cell dynamics, and disease evolution. PMID:26871029

  14. Influence of manure age and sunlight on the community structure of cattle fecal bacteria as revealed by Illumina sequencing

    NASA Astrophysics Data System (ADS)

    Wong, K.; Shaw, T. I.; Oladeinde, A.; Molina, M.

    2013-12-01

    Fecal pollution of environmental waters is a major concern for the general public because exposure to fecal-associated pathogens can have severe impacts on human health. Stream and river impairment due to fecal pollution is largely the result of agricultural activities in the United States. In the last few years, numerous metagenomic studies utilized next generation sequencing to develop microbial community profiles by massively sequencing the 16sRNA hypervariable region. This technology supports the application of water quality assessment such as pathogen detection and fecal source tracking. The bacteria communities of samples in these studies were determined when they were freshly collected; therefore, little is known about how feces age or how environmental stress influences the microbial ecology of fecal materials. In this study we monitored bacteria community changes in cattle feces for 57 days after excretion (day 0, 2, 4 8, 15, 22, 29, 43, 57) by sequencing the 16s variable region 4, using Illumnia MiSeq. Twelve cattle feces were studied; half of the samples were directly exposed to sunlight (unshaded) and half were shaded. Results indicate that the relative abundance (RA) profile in both shaded and unshaded samples rapidly changed from day 0 to 15, but stabilized from day 22 to 57. Firmcutes were the most abundant phylum (~40%) at day 0, but were reduced to <10% by day 57. The RA of Proteobacteria was only 1% at day 0, but increased to ~50% by day 57in both shaded and unshaded samples. By the end of the study, shaded and unshaded samples had a similar RA of Firmcutes and Proteobacteria but the RA of Bacteroidetes and Actinobacteria was, respectively, about 7% lower and 10% higher for unshaded samples. UV intensity, moisture, and temperature were significantly different between shaded and unshaded plots, indicating that these environmental stresses could influence the structure of fecal bacteria community in the natural environment. According to the

  15. An age-structured population model for horseshoe crabs in the Delaware Bay area to assess harvest and egg availability for shorebirds

    USGS Publications Warehouse

    Sweka, J.A.; Smith, D.R.; Millard, M.J.

    2007-01-01

    The objective of this simulation study was to create an age-structured population model for horseshoe crabs (Limulus polyphenols) in the Delaware Bay region using best available estimates of age-specific mortality and recent harvest levels. Density dependence was incorporated using a spatial model relating egg mortality with abundance of spawning females. Combinations of annual female harvest (0, 50, 100, and 200 thousand), timing of female harvest (before or after spawning), and three levels of density-dependent egg mortality were simulated. The probability of the population increasing was high (> 80%) with low and medium egg mortality and harvest less than 200 thousand females per year. Under the high egg mortality case, the probability of the population increasing was < 50% regardless of harvest. Harvest occurring after spawning increased the probability of population growth. The number of eggs available to shorebirds was highest when egg mortality was lowest and female abundance was at its highest levels. Although harvest and egg mortality influenced population growth and food availability to shorebirds, sensitivity and elasticity analyses showed that early-life stage mortality, age 0 mortality in particular, was the most important parameter for population growth. Our modeling results indicate areas where further research is needed and suggest effective management will involve a combination of harvest management and actions to increase early juvenile survival. ?? 2007 Estuarine Research Federation.

  16. Age-related changes in pial arterial structure and blood flow in mice.

    PubMed

    Kang, Hye-Min; Sohn, Inkyung; Jung, Junyang; Jeong, Joo-Won; Park, Chan

    2016-01-01

    Age-related cerebral blood flow decreases are thought to deteriorate cognition and cause senescence, although the related mechanism is unclear. To investigate the relationships between aging and changes in cerebral blood flow and vasculature, we obtained fluorescence images of young (2-month-old) and old (12-month-old) mice using indocyanine green (ICG). First, we found that the blood flow in old mice's brains is lower than that in young mice and that old mice had more curved pial arteries and fewer pial artery junctions than young mice. Second, using Western blotting, we determined that the ratio of collagen to elastin (related to cerebral vascular wall distensibility) increased with age. Finally, we found that the peak ICG intensity and blood flow index decreased, whereas the mean transit time increased, with age in the middle cerebral artery and superior sagittal sinus. Age-related changes in pial arterial structure and composition, concurrent with the observed changes in the blood flow parameters, suggest that age-related changes in the cerebral vasculature structure and distensibility may induce altered brain blood flow.

  17. [Population structure of soil arthropod in different age Pinus massoniana plantations].

    PubMed

    Tan, Bo; Wu, Fu-zhong; Yang, Wan-qin; Zhang, Jian; Xu, Zhen-feng; Liu, Yang; Gou, Xiao-lin

    2013-04-01

    An investigation was conducted on the population structure of soil arthropod community in the 3-, 8-, 14-, 31-, and 40-years old Pinus massoniana plantations in the upper reaches of the Yangtze River in spring (May) and autumn (October), 2011, aimed to search for the scientific management of the plantation. A total of 4045 soil arthropods were collected, belonging to 57 families. Both the individual density and the taxonomic group number of the soil arthropod community decreased obviously with increasing soil depth, and this trend increased with increasing stand age. The dominant groups and ordinary groups of the soil arthropod community varied greatly with the stand age of P. massoniana plantation, and a significant difference (P<0.05) was observed in the individual density and taxonomic group number among different age P. massoniana plantations. In comparison with other stand age P. massoniana plantations, 3years old P. massoniana plantation had a significant difference in the structure and diversity of soil arthropod community, and the similarity index of the soil arthropod community was lower. The individual density, taxonomic group number, and diversity of soil arthropod community were the highest in 8-years old P. massoniana plantation, and then, decreased obviously with increasing stand age. It was suggested that the land fertility of the P. massoniana plantations could be degraded with increasing stand age, and it would be appropriate to make artificial regulation and restoration in 8-years old P. massoniana plantation.

  18. The relation between structural and functional connectivity depends on age and on task goals

    PubMed Central

    Ford, Jaclyn H.; Kensinger, Elizabeth A.

    2014-01-01

    The last decade has seen an increase in neuroimaging studies examining structural (i.e., structural integrity of white matter tracts) and functional connectivity (e.g., correlations in neural activity throughout the brain). Although structural and functional connectivity changes have often been measured independently, examining the relation between these two measures is critical to understanding the specific function of neural networks and the ways they may differ across tasks and individuals. The current study addressed this question by examining the effect of age (treated as a continuous variable) and emotional valence on the relation between functional and structural connectivity. As prior studies have suggested that prefrontal regions may guide and regulate emotional memory search via functional connections with the amygdala, the current analysis focused on functional connectivity between the left amygdala and the left prefrontal cortex, and structural integrity of the uncinate fasciculus, a white matter tract connecting prefrontal and temporal regions. Participants took part in a scanned retrieval task in which they recalled positive, negative, and neutral images associated with neutral titles. Aging was associated with a significant increase in the relation between measures of structural integrity (specifically, fractional anisotropy, or FA) along the uncinate fasciculus and functional connectivity between the left ventral prefrontal cortex and amygdala during positive event retrieval, but not negative or neutral retrieval. Notably, during negative event retrieval, age was linked to stronger structure-function relations between the amygdala and the dorsal anterior cingulate cortex, such that increased structural integrity predicted stronger negative functional connectivity in older adults only. These findings suggest that young and older adults may utilize a structural pathway to engage different retrieval and regulatory strategies, even when structural

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

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  20. Structural and vibrational relaxations during aging of an ultralow-expansion glass

    NASA Astrophysics Data System (ADS)

    Kobayashi, Hiroshi; Ohtake, Yurie; Hirata, Shu; Morinaga, Atsuo

    2016-05-01

    We accurately measured the aging of an ultralow-expansion (ULE) glass for 1250 days using a diode laser resonated in the glass cavity at -3.3 °C, where the glass has zero thermal expansion coefficient. We observed that the glass shows exponential and linear decreases in length In addition, it is theoretically shown that glass aging is a nonlinear irreversible process with the spontaneous relaxations of a linear contraction and a dissipated heat. The origin for the linear contraction is an osmotic pressure which is spontaneously generated during glass aging, and the origin for the dissipated heat is the irreversibility on thermal vibrations of molecules. The result obtained is a verification of the Glansdorff-Prigogine evolutional criterion, which is first applied to a structural relaxation phenomenon in this paper. We conclude that a glass reaches a steady nonequilibrium state, which has the dissipative structure both in a steady configurational state and in steady irreversible processes.

  1. Unveiling the structural arrangements responsible for the atomic dynamics in metallic glasses during physical aging

    PubMed Central

    Giordano, V. M.; Ruta, B

    2016-01-01

    Understanding and controlling physical aging, that is, the spontaneous temporal evolution of out-of-equilibrium systems, represents one of the greatest tasks in material science. Recent studies have revealed the existence of a complex atomic motion in metallic glasses, with different aging regimes in contrast with the typical continuous aging observed in macroscopic quantities. By combining dynamical and structural synchrotron techniques, here for the first time we directly connect previously identified microscopic structural mechanisms with the peculiar atomic motion, providing a broader unique view of their complexity. We show that the atomic scale is dominated by the interplay between two processes: rearrangements releasing residual stresses related to a cascade mechanism of relaxation, and medium range ordering processes, which do not affect the local density, likely due to localized relaxations of liquid-like regions. As temperature increases, a surprising additional secondary relaxation process sets in, together with a faster medium range ordering, likely precursors of crystallization. PMID:26787443

  2. A Hierarchical Kinetic Theory of Birth, Death and Fission in Age-Structured Interacting Populations

    NASA Astrophysics Data System (ADS)

    Chou, Tom; Greenman, Chris D.

    2016-07-01

    We develop mathematical models describing the evolution of stochastic age-structured populations. After reviewing existing approaches, we formulate a complete kinetic framework for age-structured interacting populations undergoing birth, death and fission processes in spatially dependent environments. We define the full probability density for the population-size age chart and find results under specific conditions. Connections with more classical models are also explicitly derived. In particular, we show that factorial moments for non-interacting processes are described by a natural generalization of the McKendrick-von Foerster equation, which describes mean-field deterministic behavior. Our approach utilizes mixed-type, multidimensional probability distributions similar to those employed in the study of gas kinetics and with terms that satisfy BBGKY-like equation hierarchies.

  3. [Age structure and dynamics of Quercus wutaishanica population in Lingkong Mountain of Shanxi Province, China].

    PubMed

    Zhang, Jie; Shangguan, Tie-Liang; Duan, Yi-Hao; Guo, Wei; Liu, Wei-Hua; Guo, Dong-Gang

    2014-11-01

    Using the plant survivorship theory, the age structure, and the relationship between tree height and diameter (DBH) of Quercus wutaishanica population in Lingkong Mountain were analyzed, and the static life table was compiled and the survival curve plotted. The shuttle shape in age structure of Q. wutaishanica population suggested its temporal stability. The linear regression significantly fitted the positive correlation between tree height and DBH. The maximal life expectancy was observed among the trees beyond the age of the highest mortality and coincided with the lowest point of mortality density, suggesting the strong vitality of the seedlings and young trees that survived in the natural selection and intraspecific competition. The population stability of the Q. wutaishanica population was characterized by the Deevey-II of the survival curve. The dynamic pattern was characterized by the recession in the early phase, growth in the intermediate phase, and stability in the latter phase. PMID:25898607

  4. Unveiling the structural arrangements responsible for the atomic dynamics in metallic glasses during physical aging

    NASA Astrophysics Data System (ADS)

    Giordano, V. M.; Ruta, B.

    2016-01-01

    Understanding and controlling physical aging, that is, the spontaneous temporal evolution of out-of-equilibrium systems, represents one of the greatest tasks in material science. Recent studies have revealed the existence of a complex atomic motion in metallic glasses, with different aging regimes in contrast with the typical continuous aging observed in macroscopic quantities. By combining dynamical and structural synchrotron techniques, here for the first time we directly connect previously identified microscopic structural mechanisms with the peculiar atomic motion, providing a broader unique view of their complexity. We show that the atomic scale is dominated by the interplay between two processes: rearrangements releasing residual stresses related to a cascade mechanism of relaxation, and medium range ordering processes, which do not affect the local density, likely due to localized relaxations of liquid-like regions. As temperature increases, a surprising additional secondary relaxation process sets in, together with a faster medium range ordering, likely precursors of crystallization.

  5. 76 FR 69292 - Aging Management of Stainless Steel Structures and Components in Treated Borated Water

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-08

    ... COMMISSION Aging Management of Stainless Steel Structures and Components in Treated Borated Water AGENCY... Components in Treated Borated Water.'' This LR-ISG revises the guidance in the Standard Review Plan for... treated borated water. DATES: Submit comments by December 8, 2011. Comments received after this date...

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

    ERIC Educational Resources Information Center

    Crenshaw, Edward; Robison, Kristopher

    2010-01-01

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

  7. Developmental Trajectories of Structural and Pragmatic Language Skills in School-Aged Children with Williams Syndrome

    ERIC Educational Resources Information Center

    Van Den Heuvel, E.; Manders, E.; Swillen, A.; Zink, I.

    2016-01-01

    Background: This study aimed to compare developmental courses of structural and pragmatic language skills in school-aged children with Williams syndrome (WS) and children with idiopathic intellectual disability (IID). Comparison of these language trajectories could highlight syndrome-specific developmental features. Method: Twelve monolingual…

  8. The influence of the C+N+O abundances on the determination of the relative ages of globular clusters: the case of NGC1851 and NGC6121 (M4)†

    NASA Astrophysics Data System (ADS)

    D'Antona, F.; Stetson, P. B.; Ventura, P.; Milone, A. P.; Piotto, G.; Caloi, V.

    2009-10-01

    The colour-magnitude diagram (CMD) of NGC1851 presents two subgiant branches (SGBs), probably due to the presence of two populations differing in total C+N+O (carbon+nitrogen+oxygen) content. We test the idea that a difference in total C+N+O may simulate an age difference when comparing the CMD of clusters to derive relative ages. We compare NGC1851 with NGC6121 (M4), a cluster of very similar [Fe/H]. We find that, with a suitable shift of the CMDs that brings the two red horizontal branches at the same magnitude level, the unevolved main sequence and red giant branch match, but the SGB of NGC6121 and its red giant branch `bump' are fainter than in NGC1851. In particular, the SGB of NGC6121 is even slightly fainter than the faint SGB in NGC1851. Both these features can be explained if the total C+N+O in NGC6121 is larger than that in NGC1851, even if the two clusters are coeval. We conclude by warning that different initial C+N+O abundances between two clusters, otherwise similar in metallicity and age, may lead to differences in the turnoff morphology that can be easily attributed to an age difference. Based in part on observations made with the European Southern Observatory (ESO) telescopes obtained from the ESO/ST-ECF Science Archive Facility. This paper makes use of data obtained from the Isaac Newton Group Archive which is maintained as part of the CASU Astronomical Data Centre at the Institute of Astronomy, Cambridge. ‡ E-mail: dantona@oa-roma.inaf.it (FD); peter.stetson@nrc-cnrc.gc.ca (PBS); ventura@oa-roma.inaf.it (PV); antonino.milone@unipd.it (APM); giampaolo.piotto@unipd.it (GP); vittoria.caloi@iasf-roma.inaf.it (VC)

  9. Decreased Default Mode Network connectivity correlates with age-associated structural and cognitive changes

    PubMed Central

    Vidal-Piñeiro, Didac; Valls-Pedret, Cinta; Fernández-Cabello, Sara; Arenaza-Urquijo, Eider M.; Sala-Llonch, Roser; Solana, Elisabeth; Bargalló, Núria; Junqué, Carme; Ros, Emilio; Bartrés-Faz, David

    2014-01-01

    Ageing entails cognitive and motor decline as well as brain changes such as loss of gray (GM) and white matter (WM) integrity, neurovascular and functional connectivity alterations. Regarding connectivity, reduced resting-state fMRI connectivity between anterior and posterior nodes of the Default Mode Network (DMN) relates to cognitive function and has been postulated to be a hallmark of ageing. However, the relationship between age-related connectivity changes and other neuroimaging-based measures in ageing is fragmentarily investigated. In a sample of 116 healthy elders we aimed to study the relationship between antero-posterior DMN connectivity and measures of WM integrity, GM integrity and cerebral blood flow (CBF), assessed with an arterial spin labeling sequence. First, we replicated previous findings demonstrating DMN connectivity decreases in ageing and an association between antero-posterior DMN connectivity and memory scores. The results showed that the functional connectivity between posterior midline structures and the medial prefrontal cortex was related to measures of WM and GM integrity but not to CBF. Gray and WM correlates of anterio-posterior DMN connectivity included, but were not limited to, DMN areas and cingulum bundle. These results resembled patterns of age-related vulnerability which was studied by comparing the correlates of antero-posterior DMN with age-effect maps. These age-effect maps were obtained after performing an independent analysis with a second sample including both young and old subjects. We argue that antero-posterior connectivity might be a sensitive measure of brain ageing over the brain. By using a comprehensive approach, the results provide valuable knowledge that may shed further light on DMN connectivity dysfunctions in ageing. PMID:25309433

  10. Decreased Default Mode Network connectivity correlates with age-associated structural and cognitive changes.

    PubMed

    Vidal-Piñeiro, Didac; Valls-Pedret, Cinta; Fernández-Cabello, Sara; Arenaza-Urquijo, Eider M; Sala-Llonch, Roser; Solana, Elisabeth; Bargalló, Núria; Junqué, Carme; Ros, Emilio; Bartrés-Faz, David

    2014-01-01

    Ageing entails cognitive and motor decline as well as brain changes such as loss of gray (GM) and white matter (WM) integrity, neurovascular and functional connectivity alterations. Regarding connectivity, reduced resting-state fMRI connectivity between anterior and posterior nodes of the Default Mode Network (DMN) relates to cognitive function and has been postulated to be a hallmark of ageing. However, the relationship between age-related connectivity changes and other neuroimaging-based measures in ageing is fragmentarily investigated. In a sample of 116 healthy elders we aimed to study the relationship between antero-posterior DMN connectivity and measures of WM integrity, GM integrity and cerebral blood flow (CBF), assessed with an arterial spin labeling sequence. First, we replicated previous findings demonstrating DMN connectivity decreases in ageing and an association between antero-posterior DMN connectivity and memory scores. The results showed that the functional connectivity between posterior midline structures and the medial prefrontal cortex was related to measures of WM and GM integrity but not to CBF. Gray and WM correlates of anterio-posterior DMN connectivity included, but were not limited to, DMN areas and cingulum bundle. These results resembled patterns of age-related vulnerability which was studied by comparing the correlates of antero-posterior DMN with age-effect maps. These age-effect maps were obtained after performing an independent analysis with a second sample including both young and old subjects. We argue that antero-posterior connectivity might be a sensitive measure of brain ageing over the brain. By using a comprehensive approach, the results provide valuable knowledge that may shed further light on DMN connectivity dysfunctions in ageing.

  11. Age at First Episode Modulates Diagnosis-Related Structural Brain Abnormalities in Psychosis.

    PubMed

    Pina-Camacho, Laura; Del Rey-Mejías, Ángel; Janssen, Joost; Bioque, Miquel; González-Pinto, Ana; Arango, Celso; Lobo, Antonio; Sarró, Salvador; Desco, Manuel; Sanjuan, Julio; Lacalle-Aurioles, Maria; Cuesta, Manuel J; Saiz-Ruiz, Jerónimo; Bernardo, Miguel; Parellada, Mara

    2016-03-01

    Brain volume and thickness abnormalities have been reported in first-episode psychosis (FEP). However, it is unclear if and how they are modulated by brain developmental stage (and, therefore, by age at FEP as a proxy). This is a multicenter cross-sectional case-control brain magnetic resonance imaging (MRI) study. Patients with FEP (n = 196), 65.3% males, with a wide age at FEP span (12-35 y), and healthy controls (HC) (n = 157), matched for age, sex, and handedness, were scanned at 6 sites. Gray matter volume and thickness measurements were generated for several brain regions using FreeSurfer software. The nonlinear relationship between age at scan (a proxy for age at FEP in patients) and volume and thickness measurements was explored in patients with schizophrenia spectrum disorders (SSD), affective psychoses (AFP), and HC. Earlier SSD cases (ie, FEP before 15-20 y) showed significant volume and thickness deficits in frontal lobe, volume deficits in temporal lobe, and volume enlargements in ventricular system and basal ganglia. First-episode AFP patients had smaller cingulate cortex volume and thicker temporal cortex only at early age at FEP (before 18-20 y). The AFP group also had age-constant (12-35-y age span) volume enlargements in the frontal and parietal lobe. Our study suggests that age at first episode modulates the structural brain abnormalities found in FEP patients in a nonlinear and diagnosis-dependent manner. Future MRI studies should take these results into account when interpreting samples with different ages at onset and diagnosis. PMID:26371339

  12. Age at First Episode Modulates Diagnosis-Related Structural Brain Abnormalities in Psychosis.

    PubMed

    Pina-Camacho, Laura; Del Rey-Mejías, Ángel; Janssen, Joost; Bioque, Miquel; González-Pinto, Ana; Arango, Celso; Lobo, Antonio; Sarró, Salvador; Desco, Manuel; Sanjuan, Julio; Lacalle-Aurioles, Maria; Cuesta, Manuel J; Saiz-Ruiz, Jerónimo; Bernardo, Miguel; Parellada, Mara

    2016-03-01

    Brain volume and thickness abnormalities have been reported in first-episode psychosis (FEP). However, it is unclear if and how they are modulated by brain developmental stage (and, therefore, by age at FEP as a proxy). This is a multicenter cross-sectional case-control brain magnetic resonance imaging (MRI) study. Patients with FEP (n = 196), 65.3% males, with a wide age at FEP span (12-35 y), and healthy controls (HC) (n = 157), matched for age, sex, and handedness, were scanned at 6 sites. Gray matter volume and thickness measurements were generated for several brain regions using FreeSurfer software. The nonlinear relationship between age at scan (a proxy for age at FEP in patients) and volume and thickness measurements was explored in patients with schizophrenia spectrum disorders (SSD), affective psychoses (AFP), and HC. Earlier SSD cases (ie, FEP before 15-20 y) showed significant volume and thickness deficits in frontal lobe, volume deficits in temporal lobe, and volume enlargements in ventricular system and basal ganglia. First-episode AFP patients had smaller cingulate cortex volume and thicker temporal cortex only at early age at FEP (before 18-20 y). The AFP group also had age-constant (12-35-y age span) volume enlargements in the frontal and parietal lobe. Our study suggests that age at first episode modulates the structural brain abnormalities found in FEP patients in a nonlinear and diagnosis-dependent manner. Future MRI studies should take these results into account when interpreting samples with different ages at onset and diagnosis.

  13. The Knowledge of Memory Aging Questionnaire: Factor Structure and Correlates in a Lifespan Sample

    PubMed Central

    Calamia, Matthew; Reese-Melancon, Celinda; Cherry, Katie E.; Hawley, Karri S.; Jazwinski, S. Michal

    2016-01-01

    The authors examined the factor structure of the Knowledge of Memory Aging Questionnaire (KMAQ) [1] using confirmatory factor analysis in a lifespan sample of 933 individuals who ranged in age from 18 to 101. Participants were college students at Louisiana State University and adults from the community enrolled in the Louisiana Healthy Aging Study (LHAS). A two-factor solution was expected, consistent with the normal and pathological memory aging dimensions that comprise the KMAQ. A bi-factor solution with items loading on a general response bias factor and either a normal or pathological knowledge-specific factor showed good model fit. Knowledge scores were correlated with demographic and cognitive performance variables. Implications of these data for clinical settings and research are considered. PMID:27505021

  14. The role of age structure in the persistence of a chronic pathogen in a fluctuating population.

    PubMed

    Laverty, Sean M; Adler, Frederick R

    2009-03-01

    Small mammal populations exhibit large fluctuations, potentially leading to local extinction of specialist pathogens after bottlenecks. Pathogen persistence in recovering populations depends on the epidemiological characteristics of the hosts that survive the bottlenecks. Sin Nombre virus is a largely asymptomatic infection of deer mice, which creates a chronic lifelong infection. Earlier work on this virus has shown that males play a key role in pathogen persistence through a combination of longer lifespan and higher seroprevalence. Other evidence indicates that mouse age could play an equally important role, as older mice may have higher survivorship and higher contact rates. We use age structured models to examine the relationships among prevalence, age-dependent demographics, and age-dependent epidemiology.

  15. The Knowledge of Memory Aging Questionnaire: Factor Structure and Correlates in a Lifespan Sample.

    PubMed

    Calamia, Matthew; Reese-Melancon, Celinda; Cherry, Katie E; Hawley, Karri S; Jazwinski, S Michal

    2016-03-01

    The authors examined the factor structure of the Knowledge of Memory Aging Questionnaire (KMAQ) [1] using confirmatory factor analysis in a lifespan sample of 933 individuals who ranged in age from 18 to 101. Participants were college students at Louisiana State University and adults from the community enrolled in the Louisiana Healthy Aging Study (LHAS). A two-factor solution was expected, consistent with the normal and pathological memory aging dimensions that comprise the KMAQ. A bi-factor solution with items loading on a general response bias factor and either a normal or pathological knowledge-specific factor showed good model fit. Knowledge scores were correlated with demographic and cognitive performance variables. Implications of these data for clinical settings and research are considered. PMID:27505021

  16. Short interspersed nuclear elements (SINEs) are abundant in Solanaceae and have a family-specific impact on gene structure and genome organization.

    PubMed

    Seibt, Kathrin M; Wenke, Torsten; Muders, Katja; Truberg, Bernd; Schmidt, Thomas

    2016-05-01

    Short interspersed nuclear elements (SINEs) are highly abundant non-autonomous retrotransposons that are widespread in plants. They are short in size, non-coding, show high sequence diversity, and are therefore mostly not or not correctly annotated in plant genome sequences. Hence, comparative studies on genomic SINE populations are rare. To explore the structural organization and impact of SINEs, we comparatively investigated the genome sequences of the Solanaceae species potato (Solanum tuberosum), tomato (Solanum lycopersicum), wild tomato (Solanum pennellii), and two pepper cultivars (Capsicum annuum). Based on 8.5 Gbp sequence data, we annotated 82 983 SINE copies belonging to 10 families and subfamilies on a base pair level. Solanaceae SINEs are dispersed over all chromosomes with enrichments in distal regions. Depending on the genome assemblies and gene predictions, 30% of all SINE copies are associated with genes, particularly frequent in introns and untranslated regions (UTRs). The close association with genes is family specific. More than 10% of all genes annotated in the Solanaceae species investigated contain at least one SINE insertion, and we found genes harbouring up to 16 SINE copies. We demonstrate the involvement of SINEs in gene and genome evolution including the donation of splice sites, start and stop codons and exons to genes, enlargement of introns and UTRs, generation of tandem-like duplications and transduction of adjacent sequence regions.

  17. Phytoplankton abundance and structure as indicator of water quality in the drainage system of the Burullus Lagoon, southern Mediterranean coast, Egypt.

    PubMed

    El-Kassas, Hala Yassin; Gharib, Samiha Mahmoud

    2016-09-01

    This study represents the first detailed account of phytoplankton community structure and seasonal succession in eight drain sites and the Brimbal Canal influx into the Burullus Lagoon. The phytoplankton characteristics were studied based on the data collected seasonally over 4 years, from summer 2012 to spring 2016. Various indices such as Palmer's and Shannon's biotic indices were used for the assessment of the water quality of the different drains. There were a total of 194 species belonging to 65 genera and 6 groups: Bacillariophyceae (76 species), Chlorophyceae (59 species), Cyanophyceae (30 species), Euglenophyceae (25 species), Dinophyceae (3 species), and Xanthophyceae (1 species). The phytoplankton community was dominated with diatoms, green algae, and euglenoids such as Cyclotella, Scenedesmus, Navicula, Nitzschia, Ankistrodesmus, Chlorella, and Euglena. Maximum and minimum phytoplankton abundance was recorded at the Brimbal Canal and Hooks Drain. Maximum and minimum species diversities (H') were found at the Hooks Drain (2.564) and Burullus Drain (2.055). Species evenness fluctuated between 0.595 (Burullus Drain) and 0.750 (West Burullus Drain). The total score of algal genus pollution index and the algal species pollution index at the different drains showed that Drain 7 and the West Burullus Drain had moderate pollution, and the total score of the other drains were greater than 20 indicating the confirmed high organic pollution. Thus, the present investigation can be considered an attempt to use the phytoplankton community as a bioindicator of organic pollution.

  18. Phytoplankton abundance and structure as indicator of water quality in the drainage system of the Burullus Lagoon, southern Mediterranean coast, Egypt.

    PubMed

    El-Kassas, Hala Yassin; Gharib, Samiha Mahmoud

    2016-09-01

    This study represents the first detailed account of phytoplankton community structure and seasonal succession in eight drain sites and the Brimbal Canal influx into the Burullus Lagoon. The phytoplankton characteristics were studied based on the data collected seasonally over 4 years, from summer 2012 to spring 2016. Various indices such as Palmer's and Shannon's biotic indices were used for the assessment of the water quality of the different drains. There were a total of 194 species belonging to 65 genera and 6 groups: Bacillariophyceae (76 species), Chlorophyceae (59 species), Cyanophyceae (30 species), Euglenophyceae (25 species), Dinophyceae (3 species), and Xanthophyceae (1 species). The phytoplankton community was dominated with diatoms, green algae, and euglenoids such as Cyclotella, Scenedesmus, Navicula, Nitzschia, Ankistrodesmus, Chlorella, and Euglena. Maximum and minimum phytoplankton abundance was recorded at the Brimbal Canal and Hooks Drain. Maximum and minimum species diversities (H') were found at the Hooks Drain (2.564) and Burullus Drain (2.055). Species evenness fluctuated between 0.595 (Burullus Drain) and 0.750 (West Burullus Drain). The total score of algal genus pollution index and the algal species pollution index at the different drains showed that Drain 7 and the West Burullus Drain had moderate pollution, and the total score of the other drains were greater than 20 indicating the confirmed high organic pollution. Thus, the present investigation can be considered an attempt to use the phytoplankton community as a bioindicator of organic pollution. PMID:27553944

  19. Chemical abundance of comets

    NASA Technical Reports Server (NTRS)

    Wyckoff, Susan; Wehinger, Peter

    1988-01-01

    Observations of NH2, (OI) and molecular ion spectra in comets represent virtually all of the volatile fraction of a comet nucleus. Their study leads to the N2, NH3, H2O, CO2, CO content of the nucleus, and thus to important constraints on models of comet formation and chemical processing in the primitive solar nebula. The observations of Comet Halley provide the opportunity for the first comprehensive determination of the abundances in a comet nucleus. The carbon isotope abundance ratio 12 C/13 C = 65 plus or minus 8 has been determined for Comet Halley from resolved rotational line structure in the CN B-X (0,0) band. The ratio is approximately 30 pct lower than the solar system value, 89, indicating either an enhancement of 13CN or a depletion of 12CN in the comet. Scenarios consistent with the observed carbon isotope ratio are: (1) formation of the comet at the periphery of the solar nebula in a fractionation-enriched 13CN region, or hidden from 12CN enrichment sources, and (2) capture of an interestellar comet. Long-slit charge coupled device (CCD) spectra obtained at the time of the spacecraft encounter of Comet Halley have also been analyzed. Scale lengths, production rates and column densities of CH, CN, C2 and NH2 were determined.

  20. An artificial intelligence-based structural health monitoring system for aging aircraft

    NASA Technical Reports Server (NTRS)

    Grady, Joseph E.; Tang, Stanley S.; Chen, K. L.

    1993-01-01

    To reduce operating expenses, airlines are now using the existing fleets of commercial aircraft well beyond their originally anticipated service lives. The repair and maintenance of these 'aging aircraft' has therefore become a critical safety issue, both to the airlines and the Federal Aviation Administration. This paper presents the results of an innovative research program to develop a structural monitoring system that will be used to evaluate the integrity of in-service aerospace structural components. Currently in the final phase of its development, this monitoring system will indicate when repair or maintenance of a damaged structural component is necessary.

  1. Electromechanical and structural alterations in the aging rabbit heart and aorta

    PubMed Central

    Cooper, Leroy L.; Odening, Katja E.; Hwang, Min-Sig; Chaves, Leonard; Schofield, Lorraine; Taylor, Chantel A.; Gemignani, Anthony S.; Mitchell, Gary F.; Forder, John R.; Choi, Bum-Rak

    2012-01-01

    Aging increases the risk for arrhythmias and sudden cardiac death (SCD). We aimed at elucidating aging-related electrical, functional, and structural changes in the heart and vasculature that account for this heightened arrhythmogenic risk. Young (5–9 mo) and old (3.5–6 yr) female New Zealand White (NZW) rabbits were subjected to in vivo hemodynamic, electrophysiological, and echocardiographic studies as well as ex vivo optical mapping, high-field magnetic resonance imaging (MRI), and histochemical experiments. Aging increased aortic stiffness (baseline pulse wave velocity: young, 3.54 ± 0.36 vs. old, 4.35 ± 0.28 m/s, P < 0.002) and diastolic (end diastolic pressure-volume relations: 3.28 ± 0.5 vs. 4.95 ± 1.5 mmHg/ml, P < 0.05) and systolic (end systolic pressure-volume relations: 20.56 ± 4.2 vs. 33.14 ± 8.4 mmHg/ml, P < 0.01) myocardial elastances in old rabbits. Electrophysiological and optical mapping studies revealed age-related slowing of ventricular and His-Purkinje conduction (His-to-ventricle interval: 23 ± 2.5 vs. 31.9 ± 2.9 ms, P < 0.0001), altered conduction anisotropy, and a greater inducibility of ventricular fibrillation (VF, 3/12 vs. 7/9, P < 0.05) in old rabbits. Histochemical studies confirmed an aging-related increased fibrosis in the ventricles. MRI showed a deterioration of the free-running Purkinje fiber network in ventricular and septal walls in old hearts as well as aging-related alterations of the myofibrillar orientation and myocardial sheet structure that may account for this slowed conduction velocity. Aging leads to parallel stiffening of the aorta and the heart, including an increase in systolic stiffness and contractility and diastolic stiffness. Increasingly, anisotropic conduction velocity due to fibrosis and altered myofibrillar orientation and myocardial sheet structure may contribute to the pathogenesis of VF in old hearts. The aging rabbit model represents a useful tool for elucidating age-related changes that

  2. Population Genetic Structure, Abundance, and Health Status of Two Dominant Benthic Species in the Saba Bank National Park, Caribbean Netherlands: Montastraea cavernosa and Xestospongia muta.

    PubMed

    de Bakker, Didier M; Meesters, Erik H W G; van Bleijswijk, Judith D L; Luttikhuizen, Pieternella C; Breeuwer, Hans J A J; Becking, Leontine E

    2016-01-01

    Saba Bank, a submerged atoll in the Caribbean Sea with an area of 2,200 km2, has attained international conservation status due to the rich diversity of species that reside on the bank. In order to assess the role of Saba Bank as a potential reservoir of diversity for the surrounding reefs, we examined the population genetic structure, abundance and health status of two prominent benthic species, the coral Montastraea cavernosa and the sponge Xestospongia muta. Sequence data were collected from 34 colonies of M. cavernosa (nDNA ITS1-5.8S-ITS2; 892 bp) and 68 X. muta sponges (mtDNA I3-M11 partition of COI; 544 bp) on Saba Bank and around Saba Island, and compared with published data across the wider Caribbean. Our data indicate that there is genetic connectivity between populations on Saba Bank and the nearby Saba Island as well as multiple locations in the wider Caribbean, ranging in distance from 100s-1000s km. The genetic diversity of Saba Bank populations of M. cavernosa (π = 0.055) and X. muta (π = 0.0010) was comparable to those in other regions in the western Atlantic. Densities and health status were determined along 11 transects of 50 m2 along the south-eastern rim of Saba Bank. The densities of M. cavernosa (0.27 ind. m-2, 95% CI: 0.12-0.52) were average, while the densities of X. muta (0.09 ind. m-2, 95% CI: 0.02-0.32) were generally higher with respect to other Caribbean locations. No disease or bleaching was present in any of the specimens of the coral M. cavernosa, however, we did observe partial tissue loss (77.9% of samples) as well as overgrowth (48.1%), predominantly by cyanobacteria. In contrast, the majority of observed X. muta (83.5%) showed signs of presumed bleaching. The combined results of apparent gene flow among populations on Saba Bank and surrounding reefs, the high abundance and unique genetic diversity, indicate that Saba Bank could function as an important buffer for the region. Either as a natural source of larvae to replenish

  3. Population Genetic Structure, Abundance, and Health Status of Two Dominant Benthic Species in the Saba Bank National Park, Caribbean Netherlands: Montastraea cavernosa and Xestospongia muta

    PubMed Central

    de Bakker, Didier M.; Meesters, Erik H. W. G.; van Bleijswijk, Judith D. L.; Luttikhuizen, Pieternella C.; Breeuwer, Hans J. A. J.; Becking, Leontine E.

    2016-01-01

    Saba Bank, a submerged atoll in the Caribbean Sea with an area of 2,200 km2, has attained international conservation status due to the rich diversity of species that reside on the bank. In order to assess the role of Saba Bank as a potential reservoir of diversity for the surrounding reefs, we examined the population genetic structure, abundance and health status of two prominent benthic species, the coral Montastraea cavernosa and the sponge Xestospongia muta. Sequence data were collected from 34 colonies of M. cavernosa (nDNA ITS1-5.8S-ITS2; 892 bp) and 68 X. muta sponges (mtDNA I3-M11 partition of COI; 544 bp) on Saba Bank and around Saba Island, and compared with published data across the wider Caribbean. Our data indicate that there is genetic connectivity between populations on Saba Bank and the nearby Saba Island as well as multiple locations in the wider Caribbean, ranging in distance from 100s–1000s km. The genetic diversity of Saba Bank populations of M. cavernosa (π = 0.055) and X. muta (π = 0.0010) was comparable to those in other regions in the western Atlantic. Densities and health status were determined along 11 transects of 50 m2 along the south-eastern rim of Saba Bank. The densities of M. cavernosa (0.27 ind. m-2, 95% CI: 0.12–0.52) were average, while the densities of X. muta (0.09 ind. m-2, 95% CI: 0.02–0.32) were generally higher with respect to other Caribbean locations. No disease or bleaching was present in any of the specimens of the coral M. cavernosa, however, we did observe partial tissue loss (77.9% of samples) as well as overgrowth (48.1%), predominantly by cyanobacteria. In contrast, the majority of observed X. muta (83.5%) showed signs of presumed bleaching. The combined results of apparent gene flow among populations on Saba Bank and surrounding reefs, the high abundance and unique genetic diversity, indicate that Saba Bank could function as an important buffer for the region. Either as a natural source of larvae to

  4. Population Genetic Structure, Abundance, and Health Status of Two Dominant Benthic Species in the Saba Bank National Park, Caribbean Netherlands: Montastraea cavernosa and Xestospongia muta.

    PubMed

    de Bakker, Didier M; Meesters, Erik H W G; van Bleijswijk, Judith D L; Luttikhuizen, Pieternella C; Breeuwer, Hans J A J; Becking, Leontine E

    2016-01-01

    Saba Bank, a submerged atoll in the Caribbean Sea with an area of 2,200 km2, has attained international conservation status due to the rich diversity of species that reside on the bank. In order to assess the role of Saba Bank as a potential reservoir of diversity for the surrounding reefs, we examined the population genetic structure, abundance and health status of two prominent benthic species, the coral Montastraea cavernosa and the sponge Xestospongia muta. Sequence data were collected from 34 colonies of M. cavernosa (nDNA ITS1-5.8S-ITS2; 892 bp) and 68 X. muta sponges (mtDNA I3-M11 partition of COI; 544 bp) on Saba Bank and around Saba Island, and compared with published data across the wider Caribbean. Our data indicate that there is genetic connectivity between populations on Saba Bank and the nearby Saba Island as well as multiple locations in the wider Caribbean, ranging in distance from 100s-1000s km. The genetic diversity of Saba Bank populations of M. cavernosa (π = 0.055) and X. muta (π = 0.0010) was comparable to those in other regions in the western Atlantic. Densities and health status were determined along 11 transects of 50 m2 along the south-eastern rim of Saba Bank. The densities of M. cavernosa (0.27 ind. m-2, 95% CI: 0.12-0.52) were average, while the densities of X. muta (0.09 ind. m-2, 95% CI: 0.02-0.32) were generally higher with respect to other Caribbean locations. No disease or bleaching was present in any of the specimens of the coral M. cavernosa, however, we did observe partial tissue loss (77.9% of samples) as well as overgrowth (48.1%), predominantly by cyanobacteria. In contrast, the majority of observed X. muta (83.5%) showed signs of presumed bleaching. The combined results of apparent gene flow among populations on Saba Bank and surrounding reefs, the high abundance and unique genetic diversity, indicate that Saba Bank could function as an important buffer for the region. Either as a natural source of larvae to replenish

  5. VizieR Online Data Catalog: High-precision abundances for stars with planets (Ramirez+, 2014)

    NASA Astrophysics Data System (ADS)

    Ramirez, I.; Melendez, J.; Asplund, M.

    2013-11-01

    High-precision stellar parameters and chemical abundances are presented for 111 stars; 52 of them are late-F type dwarfs and 59 are metal-rich solar analogs. The atomic linelist employed in the derivation of chemical abundances is also given. This linelist includes hyperfine structure parameters for some species. The stars' isochrone masses and ages are also reported, along with estimates of chromospheric activity. (5 data files).

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

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  7. Age structure of owned dogs under compulsory culling in a visceral leishmaniasis endemic area.

    PubMed

    Bortoletto, Danielly Vieira; Utsunomiya, Yuri Tani; Perri, Silvia Helena Venturoli; Ferreira, Fernando; Nunes, Cáris Maroni

    2016-01-01

    The age structure of the dog population is essential for planning and evaluating control programs for zoonotic diseases. We analyzed data of an owned-dog census in order to characterize, for the first time, the structure of a dog population under compulsory culling in a visceral leishmaniasis endemic area (Panorama, São Paulo State, Brazil) that recorded a dog-culling rate of 28% in the year of the study. Data on 1,329 households and 1,671 owned dogs revealed an owned dog:human ratio of 1:7. The mean age of dogs was estimated at 1.73 years; the age pyramid indicated high birth and mortality rates at the first year of age with an estimated cumulative mortality of 78% at the third year of age and expected life span of 2.75 years. In spite of the high mortality, a growth projection simulation suggested that the population has potential to grow in a logarithmic scale over the years. The estimated parameters can be further applied in models to maximize the impact and minimize financial inputs of visceral leishmaniasis control measures. PMID:27598014

  8. The effect of gender and age structure on municipal waste generation in Poland

    SciTech Connect

    Talalaj, Izabela Anna Walery, Maria

    2015-06-15

    Highlights: • An effect of gender and age structure on municipal waste generation was presented. • The waste accumulation index is influenced by a number of unemployed women. • Greater share of women in society contributes to greater waste production. • A model describing the analyzed dependences was determined. - Abstract: In this study the effect of gender and age structure on municipal waste generation was investigated. The data from 10-year period, from 2001 to 2010 year, were taken into consideration. The following parameters of gender and age structure were analyzed: men and woman quantity, female to male ratio, number of working, pre-working and post-working age men/women, number of unemployed men/women. The results have showed a strong correlation of annual per capita waste generation rate with number of unemployed women (r = 0.70) and female to male ratio (r = 0.81). This indicates that waste generation rate is more depended on ratio of men and women that on quantitative size of each group. Using the regression analysis a model describing the dependence between female to male ratio, number of unemployed woman and waste quantity was determined. The model explains 70% of waste quantity variation. Obtained results can be used both to improve waste management and to a fuller understanding of gender behavior.

  9. Structural degradation of acrylic bone cements due to in vivo and simulated aging.

    PubMed

    Hughes, Kerry F; Ries, Michael D; Pruitt, Lisa A

    2003-05-01

    Acrylic bone cement is the primary load-bearing material used for the attachment of orthopedic devices to adjoining bone. Degradation of acrylic-based cements in vivo results in a loss of structural integrity of the bone-cement-prosthesis interface and limits the longevity of cemented orthopedic implants. The purpose of this study is to investigate the effect of in vivo aging on the structure of the acrylic bone cement and to develop an in vitro artificial aging protocol that mimics the observed degradation. Three sets of retrievals are examined in this study: Palacos brand cement retrieved from hip replacements, and Simplex brand cement retrieved from both hip and knee replacement surgeries. In vitro aging is performed using oxidative and acidic environments on three acrylic-based cements: Palacos, Simplex, and CORE. Gel permeation chromatography (GPC) and Fourier transform infrared spectroscopy (FTIR) are used to examine the evolution of molecular weight and chemical species within the acrylic cements due to both in vivo and simulated aging. GPC analysis indicates that molecular weight is degraded in the hip retrievals but not in the knee retrievals. Artificial aging in an oxidative environment best reproduces this degradation mechanism. FTIR analysis indicates that there exists a chemical evolution within the cement due to in vivo and in vitro aging. These findings are consistent with scission-based degradation schemes in the cement. Based on the results of this study, a pathway for structural degradation of acrylic bone cement is proposed. The findings from this investigation have broad applicability to acrylic-based cements and may provide guidance for the development of new bone cements that resist degradation in the body.

  10. Motor structures in female volleyball players aged 14-17 according to technique quality and performance.

    PubMed

    Katić, Ratko; Grgantov, Zoran; Jurko, Damir

    2006-03-01

    The aim of the study was to identify motor structures in elite female volleyball players aged 14-17, and to assess the effect of these motor structures on their technical and situation efficiency. For this purpose, a battery of 12 motor tests as predictor variables, and a set of six technical elements and evaluation of performance quality as criterion variables were applied in a sample of 147 female volleyballers aged 14-15 and a sample of 50 female volleyballers aged 16-17. Analysis of variance between subgroups within the groups of volleyballers aged 14-15 and those aged 16-17 showed the results on all motor tests to improve with the increase in situation performance, which was especially pronounced in the tests assessing explosive strength and agility. The same held true for the results on all tests assessing volleyball techniques, spike and block in particular. In both samples, factor analysis of motor tests isolated two factors underlain by the generation and regulation of strength, and the mechanism of speed regulation. Canonical correlation analysis between the motor regulatory mechanisms and technical elements revealed determination of the mechanisms of strength and technical efficiency in both samples. Regression correlation analysis showed the mechanisms of strength regulation and speed to be good predictors of game performance in female volleyballers aged 14-15 and 16-17, whereby the mechanism of strength regulation had greater effect on the game performance than the mechanism of speed regulation. Regression correlation analysis also revealed the set of 6 techniques evaluated to be a good predictor of situation efficiency in both groups of female volleyballers aged 14-15 and 16-17. The block and spike techniques were found to be the best predictors of game performance quality in the former, and the techniques of spike and block in the latter. Based on the results obtained, a possible model of selection for supreme score achievement in female volleyball

  11. Age and decision strategies in running memory for speech: effects of prosody and linguistic structure.

    PubMed

    Wingfield, A; Lahar, C J; Stine, E A

    1989-07-01

    Young and elderly adults heard recorded passages of English prose spoken with and without normal prosody, and passages that were devoid of either linguistic or prosodic structure. Subjects were instructed to interrupt the speech input at points of their choosing for immediate recall on a segment-by-segment basis. For both age groups segmentation strategies varied with type of speech materials as did their levels of recall accuracy. Age differences in recall performance were diminished by the presence of normal prosody, an effect only partially attributable to the use of prosody to detect linguistic boundaries at the surface level.

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

    PubMed

    Lessard, Sabin; Soares, Cintia

    2016-02-21

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

  13. Age-associated differences on structural brain MRI in nondemented individuals from 71 to 103 years.

    PubMed

    Yang, Zixuan; Wen, Wei; Jiang, Jiyang; Crawford, John D; Reppermund, Simone; Levitan, Charlene; Slavin, Melissa J; Kochan, Nicole A; Richmond, Robyn L; Brodaty, Henry; Trollor, Julian N; Sachdev, Perminder S

    2016-04-01

    Successful brain aging in the oldest old (≥90 years) is underexplored. This study examined cross-sectional brain morphological differences from 8th to 11th decades of life in nondemented individuals by high-resolution magnetic resonance imaging. Two hundred seventy-seven nondemented community-dwelling participants (71-103 years) from Sydney Memory and Ageing Study and Sydney Centenarian Study comprised the sample, including a subsample of 160 cognitively high-functioning elders. Relationships between age and magnetic resonance imaging-derived measurements were studied using general linear models; and structural profiles of the ≥90 years were delineated. In full sample and the subsample, significant linear negative relationship of gray matter with age was found, with the greatest age effects in the medial temporal lobe and parietal and occipital cortices. This pattern was further confirmed by comparing directly the ≥90 years to the 71-89 years groups. Significant quadratic age effects on total white matter and white matter hyperintensities were observed. Our study demonstrated heterogeneous differences across brain regions between the oldest old and young old, with an emphasis on hippocampus, temporoposterior cortex, and white matter hyperintensities. PMID:26973107

  14. Age and disease-related structural changes in the retinal pigment epithelium

    PubMed Central

    Bonilha, Vera L

    2008-01-01

    As the retinal pigment epithelium (RPE) ages, a number of structural changes occur, including loss of melanin granules, increase in the density of residual bodies, accumulation of lipofuscin, accumulation of basal deposits on or within Bruch’s membrane, formation of drusen (between the basal lamina of the RPE and the inner collagenous layer of Bruch’s membrane), thickening of Bruch’s membrane, microvilli atrophy and disorganization of the basal infoldings. Although these changes are well known, the basic mechanisms involved in them are frequently poorly understood. These age-related changes progress slowly and vary in severity in different individuals. These changes are also found in age-related macular degeneration (AMD), a late onset disease that severely impacts the RPE, but they are much more pronounced than during normal aging. However, the changes in AMD lead to severe loss of vision. Given the many supporting functions which the RPE serves for the retina, it is important to decipher the age-related changes in this epithelium in order to understand age-related changes in vision. PMID:19668732

  15. [Intergenerational communication by age-integrating structures? Remarks on on gerontologic utopia].

    PubMed

    Amrhein, L

    2002-08-01

    In their "aging and society" paradigm Riley and collaborators conceptualize the ideal type of an age-integrated society in which the social segregation of different age groups is removed. They claim that in the future the life-world areas of education, work and leisure will no longer exclusively follow the triple division of the life course but will be visited repeatedly in different phases of life. Therefore, they argue, age barriers would be dissolved in many areas, which would lead to more contact and cooperation and to a greater solidarity between the generations. This conception shall be rejected as an utopia because it contradicts central functional mechanisms of modern societies; at best it might be imagined as a "reflexive modernization" of age-segregated structures. A certain distance and alienation between the generations remains a direct, though unintended product of the modernization process and cannot be reversed without welfare losses. A dialogue of generations as a societal project, therefore, implies that the functional differentiation into age groups and life stages will be accepted without referring to pre-modern idealizations of generational relationships.

  16. ALPS: The Age-Layered Population Structure for Reducing the Problem of Premature Convergence

    NASA Technical Reports Server (NTRS)

    Hornby, Gregory S.

    2006-01-01

    To reduce the problem of premature convergence we define a new attribute of an individual, its age, and propose the Age-Layered Population Structure (ALPS), in which age is used to restrict competition and breeding between members of the population. ALPS differs from a typical EA by segregating individuals into different age-layers by their age - a measure of how long the genetic material has been in the population - and by regularly replacing all individuals in the bottom layer with randomly generated ones. The introduction of new, randomly generated individuals at regular intervals results in an EA that is never completely converged and is always looking at new parts of the fitness landscape. By using age to restrict competition and breeding search is able to develop promising young individuals without them being dominated by older ones. We demonstrate the effectiveness of the ALPS algorithm on an antenna design problem in which evolution with ALPS produces antennas more than twice as good as does evolution with two other types of EAs. Further analysis shows that the ALPS model does allow the offspring of newly generated individuals to move the population out of mediocre local-optima to better parts of the fitness landscape.

  17. Gonotrophic development and survival in field populations of Musca domestica (Diptera: Muscidae) at dairies in California, Minnesota, and Georgia, and the relationship of fly age to relative abundance of (Z)-9-tricosene (muscalure).

    PubMed

    Butler, S M; Moon, R D; Hinkle, N C; Millar, J G; McElfresh, J S; Mullens, B A

    2013-07-01

    Adult female Musca domestica L. were collected in 2004 and 2005 from dairies in California, Minnesota, and Georgia. Relative abundance of (Z)-9-tricosene (muscalure) among the dominant eight hydrocarbons was determined. Fly heads then were removed to quantify pterin levels and estimate fly age, abdomens were dissected to score gonotrophic development and parity (follicular relics), and spermathecae were examined for sperm. Daily survival was assessed using two estimates of time required to become gravid: laboratory-based degree-day (DD) estimates and estimates based on pterin values in field-collected flies matched to their stages of gonotrophic development. Among newly emerged females (oocyte stage 1) with detectable muscalure, it comprised < approximately 1.5% of cuticular hydrocarbons. In muscalure-positive flies, muscalure comprised a higher proportion of cuticular hydrocarbons in older flies from California and Minnesota (6-9% when gravid) versus flies from Georgia (<2% when gravid). Females mated in early-intermediate stages of egg development. Life expectancy, using laboratory-derived estimates of time needed to become gravid, ranged from 3.6 to 10.6 d. Using equivalent pterin-based time estimates, life expectancy ranged from 4.0 to 19.5 d. Mean DD ages (12 degrees C threshold) of gravid flies varied widely (53-95 DD) and were congruent with laboratory-based estimates (52-57 DD) in only 7 of 12 farm-year combinations. Thus, house flies under natural conditions often required more time to develop eggs than laboratory models would predict, extending daily survival estimates based on gonotrophic age by 11-74%.

  18. Aged nano-structured platinum based catalyst: effect of chemical treatment on adsorption and catalytic activity.

    PubMed

    Shim, Wang Geun; Nahm, Seung Won; Park, Hyuk Ryeol; Yun, Hyung Sun; Seo, Seong Gyu; Kim, Sang Chai

    2011-02-01

    To examine the effect of chemical treatment on the adsorption and catalytic activity of nanostructured platinum based catalyst, the aged commercial Pt/AC catalyst was pretreated with sulfuric acid (H2SO4) and a cleaning agent (Hexane). Several reliable methods such as nitrogen adsorption, X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and inductively coupled plasma (ICP) were employed to characterize the aged Pt/AC catalyst and its chemically pretreated Pt/AC catalysts. The catalytic and adsorption activities of nano-structured heterogeneous Pt/AC catalyst were investigated on the basis of toluene oxidation and adsorption isotherm data. In addition, the adsorption isotherms of toluene were used to calculate the adsorption energy distribution functions for the parent catalyst and its pre-treated nano-structured Pt/AC catalysts. It was found that sulfuric acid aqueous treatment can enhance the catalytic performance of aged Pt/AC catalyst toward catalytic oxidation of toluene. It was also shown that a comparative analysis of the energy distribution functions for nano-structured Pt/AC catalysts as well as the pore size distribution provides valuable information about their structural and energetic heterogeneity.

  19. Genus age, provincial area and the taxonomic structure of marine faunas

    PubMed Central

    Harnik, Paul G.; Jablonski, David; Krug, Andrew Z.; Valentine, James W.

    2010-01-01

    Species are unevenly distributed among genera within clades and regions, with most genera species-poor and few species-rich. At regional scales, this structure to taxonomic diversity is generated via speciation, extinction and geographical range dynamics. Here, we use a global database of extant marine bivalves to characterize the taxonomic structure of climate zones and provinces. Our analyses reveal a general, Zipf–Mandelbrot form to the distribution of species among genera, with faunas from similar climate zones exhibiting similar taxonomic structure. Provinces that contain older taxa and/or encompass larger areas are expected to be more species-rich. Although both median genus age and provincial area correlate with measures of taxonomic structure, these relationships are interdependent, nonlinear and driven primarily by contrasts between tropical and extra-tropical faunas. Provincial area and taxonomic structure are largely decoupled within climate zones. Counter to the expectation that genus age and species richness should positively covary, diverse and highly structured provincial faunas are dominated by young genera. The marked differences between tropical and temperate faunas suggest strong spatial variation in evolutionary rates and invasion frequencies. Such variation contradicts biogeographic models that scale taxonomic diversity to geographical area. PMID:20534619

  20. Genus age, provincial area and the taxonomic structure of marine faunas.

    PubMed

    Harnik, Paul G; Jablonski, David; Krug, Andrew Z; Valentine, James W

    2010-11-22

    Species are unevenly distributed among genera within clades and regions, with most genera species-poor and few species-rich. At regional scales, this structure to taxonomic diversity is generated via speciation, extinction and geographical range dynamics. Here, we use a global database of extant marine bivalves to characterize the taxonomic structure of climate zones and provinces. Our analyses reveal a general, Zipf-Mandelbrot form to the distribution of species among genera, with faunas from similar climate zones exhibiting similar taxonomic structure. Provinces that contain older taxa and/or encompass larger areas are expected to be more species-rich. Although both median genus age and provincial area correlate with measures of taxonomic structure, these relationships are interdependent, nonlinear and driven primarily by contrasts between tropical and extra-tropical faunas. Provincial area and taxonomic structure are largely decoupled within climate zones. Counter to the expectation that genus age and species richness should positively covary, diverse and highly structured provincial faunas are dominated by young genera. The marked differences between tropical and temperate faunas suggest strong spatial variation in evolutionary rates and invasion frequencies. Such variation contradicts biogeographic models that scale taxonomic diversity to geographical area. PMID:20534619

  1. Effects of Age and Hearing Loss on the Processing of Auditory Temporal Fine Structure.

    PubMed

    Moore, Brian C J

    2016-01-01

    Within the cochlea, broadband sounds like speech and music are filtered into a series of narrowband signals, each of which can be considered as a relatively slowly varying envelope (ENV) imposed on a rapidly oscillating carrier (the temporal fine structure, TFS). Information about ENV and TFS is conveyed in the timing and short-term rate of nerve spikes in the auditory nerve. There is evidence that both hearing loss and increasing age adversely affect the ability to use TFS information, but in many studies the effects of hearing loss and age have been confounded. This paper summarises evidence from studies that allow some separation of the effects of hearing loss and age. The results suggest that the monaural processing of TFS information, which is important for the perception of pitch and for segregating speech from background sounds, is adversely affected by both hearing loss and increasing age, the former being more important. The monaural processing of ENV information is hardly affected by hearing loss or by increasing age. The binaural processing of TFS information, which is important for sound localisation and the binaural masking level difference, is also adversely affected by both hearing loss and increasing age, but here the latter seems more important. The deterioration of binaural TFS processing with increasing age appears to start relatively early in life. The binaural processing of ENV information also deteriorates somewhat with increasing age. The reduced binaural processing abilities found for older/hearing-impaired listeners may partially account for the difficulties that such listeners experience in situations where the target speech and interfering sounds come from different directions in space, as is common in everyday life. PMID:27080640

  2. Mineral vs. Organic Amendments: Microbial Community Structure, Activity and Abundance of Agriculturally Relevant Microbes Are Driven by Long-Term Fertilization Strategies.

    PubMed

    Francioli, Davide; Schulz, Elke; Lentendu, Guillaume; Wubet, Tesfaye; Buscot, François; Reitz, Thomas

    2016-01-01

    Soil management is fundamental to all agricultural systems and fertilization practices have contributed substantially to the impressive increases in food production. Despite the pivotal role of soil microorganisms in agro-ecosystems, we still have a limited understanding of the complex response of the soil microbiota to organic and mineral fertilization in the very long-term. Here, we report the effects of different fertilization regimes (mineral, organic and combined mineral and organic fertilization), carried out for more than a century, on the structure and activity of the soil microbiome. Organic matter content, nutrient concentrations, and microbial biomass carbon were significantly increased by mineral, and even more strongly by organic fertilization. Pyrosequencing revealed significant differences between the structures of bacterial and fungal soil communities associated to each fertilization regime. Organic fertilization increased bacterial diversity, and stimulated microbial groups (Firmicutes, Proteobacteria, and Zygomycota) that are known to prefer nutrient-rich environments, and that are involved in the degradation of complex organic compounds. In contrast, soils not receiving manure harbored distinct microbial communities enriched in oligotrophic organisms adapted to nutrient-limited environments, as Acidobacteria. The fertilization regime also affected the relative abundances of plant beneficial and detrimental microbial taxa, which may influence productivity and stability of the agroecosystem. As expected, the activity of microbial exoenzymes involved in carbon, nitrogen, and phosphorous mineralization were enhanced by both types of fertilization. However, in contrast to comparable studies, the highest chitinase and phosphatase activities were observed in the solely mineral fertilized soil. Interestingly, these two enzymes showed also a particular high biomass-specific activities and a strong negative relation with soil pH. As many soil parameters

  3. Mineral vs. Organic Amendments: Microbial Community Structure, Activity and Abundance of Agriculturally Relevant Microbes Are Driven by Long-Term Fertilization Strategies

    PubMed Central

    Francioli, Davide; Schulz, Elke; Lentendu, Guillaume; Wubet, Tesfaye; Buscot, François; Reitz, Thomas

    2016-01-01

    Soil management is fundamental to all agricultural systems and fertilization practices have contributed substantially to the impressive increases in food production. Despite the pivotal role of soil microorganisms in agro-ecosystems, we still have a limited understanding of the complex response of the soil microbiota to organic and mineral fertilization in the very long-term. Here, we report the effects of different fertilization regimes (mineral, organic and combined mineral and organic fertilization), carried out for more than a century, on the structure and activity of the soil microbiome. Organic matter content, nutrient concentrations, and microbial biomass carbon were significantly increased by mineral, and even more strongly by organic fertilization. Pyrosequencing revealed significant differences between the structures of bacterial and fungal soil communities associated to each fertilization regime. Organic fertilization increased bacterial diversity, and stimulated microbial groups (Firmicutes, Proteobacteria, and Zygomycota) that are known to prefer nutrient-rich environments, and that are involved in the degradation of complex organic compounds. In contrast, soils not receiving manure harbored distinct microbial communities enriched in oligotrophic organisms adapted to nutrient-limited environments, as Acidobacteria. The fertilization regime also affected the relative abundances of plant beneficial and detrimental microbial taxa, which may influence productivity and stability of the agroecosystem. As expected, the activity of microbial exoenzymes involved in carbon, nitrogen, and phosphorous mineralization were enhanced by both types of fertilization. However, in contrast to comparable studies, the highest chitinase and phosphatase activities were observed in the solely mineral fertilized soil. Interestingly, these two enzymes showed also a particular high biomass-specific activities and a strong negative relation with soil pH. As many soil parameters

  4. Mineral vs. Organic Amendments: Microbial Community Structure, Activity and Abundance of Agriculturally Relevant Microbes Are Driven by Long-Term Fertilization Strategies.

    PubMed

    Francioli, Davide; Schulz, Elke; Lentendu, Guillaume; Wubet, Tesfaye; Buscot, François; Reitz, Thomas

    2016-01-01

    Soil management is fundamental to all agricultural systems and fertilization practices have contributed substantially to the impressive increases in food production. Despite the pivotal role of soil microorganisms in agro-ecosystems, we still have a limited understanding of the complex response of the soil microbiota to organic and mineral fertilization in the very long-term. Here, we report the effects of different fertilization regimes (mineral, organic and combined mineral and organic fertilization), carried out for more than a century, on the structure and activity of the soil microbiome. Organic matter content, nutrient concentrations, and microbial biomass carbon were significantly increased by mineral, and even more strongly by organic fertilization. Pyrosequencing revealed significant differences between the structures of bacterial and fungal soil communities associated to each fertilization regime. Organic fertilization increased bacterial diversity, and stimulated microbial groups (Firmicutes, Proteobacteria, and Zygomycota) that are known to prefer nutrient-rich environments, and that are involved in the degradation of complex organic compounds. In contrast, soils not receiving manure harbored distinct microbial communities enriched in oligotrophic organisms adapted to nutrient-limited environments, as Acidobacteria. The fertilization regime also affected the relative abundances of plant beneficial and detrimental microbial taxa, which may influence productivity and stability of the agroecosystem. As expected, the activity of microbial exoenzymes involved in carbon, nitrogen, and phosphorous mineralization were enhanced by both types of fertilization. However, in contrast to comparable studies, the highest chitinase and phosphatase activities were observed in the solely mineral fertilized soil. Interestingly, these two enzymes showed also a particular high biomass-specific activities and a strong negative relation with soil pH. As many soil parameters

  5. Mineral vs. Organic Amendments: Microbial Community Structure, Activity and Abundance of Agriculturally Relevant Microbes Are Driven by Long-Term Fertilization Strategies

    PubMed Central

    Francioli, Davide; Schulz, Elke; Lentendu, Guillaume; Wubet, Tesfaye; Buscot, François; Reitz, Thomas

    2016-01-01

    Soil management is fundamental to all agricultural systems and fertilization practices have contributed substantially to the impressive increases in food production. Despite the pivotal role of soil microorganisms in agro-ecosystems, we still have a limited understanding of the complex response of the soil microbiota to organic and mineral fertilization in the very long-term. Here, we report the effects of different fertilization regimes (mineral, organic and combined mineral and organic fertilization), carried out for more than a century, on the structure and activity of the soil microbiome. Organic matter content, nutrient concentrations, and microbial biomass carbon were significantly increased by mineral, and even more strongly by organic fertilization. Pyrosequencing revealed significant differences between the structures of bacterial and fungal soil communities associated to each fertilization regime. Organic fertilization increased bacterial diversity, and stimulated microbial groups (Firmicutes, Proteobacteria, and Zygomycota) that are known to prefer nutrient-rich environments, and that are involved in the degradation of complex organic compounds. In contrast, soils not receiving manure harbored distinct microbial communities enriched in oligotrophic organisms adapted to nutrient-limited environments, as Acidobacteria. The fertilization regime also affected the relative abundances of plant beneficial and detrimental microbial taxa, which may influence productivity and stability of the agroecosystem. As expected, the activity of microbial exoenzymes involved in carbon, nitrogen, and phosphorous mineralization were enhanced by both types of fertilization. However, in contrast to comparable studies, the highest chitinase and phosphatase activities were observed in the solely mineral fertilized soil. Interestingly, these two enzymes showed also a particular high biomass-specific activities and a strong negative relation with soil pH. As many soil parameters

  6. Structural and functional rejuvenation of the aged brain by an approved anti-asthmatic drug.

    PubMed

    Marschallinger, Julia; Schäffner, Iris; Klein, Barbara; Gelfert, Renate; Rivera, Francisco J; Illes, Sebastian; Grassner, Lukas; Janssen, Maximilian; Rotheneichner, Peter; Schmuckermair, Claudia; Coras, Roland; Boccazzi, Marta; Chishty, Mansoor; Lagler, Florian B; Renic, Marija; Bauer, Hans-Christian; Singewald, Nicolas; Blümcke, Ingmar; Bogdahn, Ulrich; Couillard-Despres, Sebastien; Lie, D Chichung; Abbracchio, Maria P; Aigner, Ludwig

    2015-10-27

    As human life expectancy has improved rapidly in industrialized societies, age-related cognitive impairment presents an increasing challenge. Targeting histopathological processes that correlate with age-related cognitive declines, such as neuroinflammation, low levels of neurogenesis, disrupted blood-brain barrier and altered neuronal activity, might lead to structural and functional rejuvenation of the aged brain. Here we show that a 6-week treatment of young (4 months) and old (20 months) rats with montelukast, a marketed anti-asthmatic drug antagonizing leukotriene receptors, reduces neuroinflammation, elevates hippocampal neurogenesis and improves learning and memory in old animals. By using gene knockdown and knockout approaches, we demonstrate that the effect is mediated through inhibition of the GPR17 receptor. This work illustrates that inhibition of leukotriene receptor signalling might represent a safe and druggable target to restore cognitive functions in old individuals and paves the way for future clinical translation of leukotriene receptor inhibition for the treatment of dementias.

  7. Structural and functional rejuvenation of the aged brain by an approved anti-asthmatic drug

    PubMed Central

    Marschallinger, Julia; Schäffner, Iris; Klein, Barbara; Gelfert, Renate; Rivera, Francisco J.; Illes, Sebastian; Grassner, Lukas; Janssen, Maximilian; Rotheneichner, Peter; Schmuckermair, Claudia; Coras, Roland; Boccazzi, Marta; Chishty, Mansoor; Lagler, Florian B.; Renic, Marija; Bauer, Hans-Christian; Singewald, Nicolas; Blümcke, Ingmar; Bogdahn, Ulrich; Couillard-Despres, Sebastien; Lie, D. Chichung; Abbracchio, Maria P.; Aigner, Ludwig

    2015-01-01

    As human life expectancy has improved rapidly in industrialized societies, age-related cognitive impairment presents an increasing challenge. Targeting histopathological processes that correlate with age-related cognitive declines, such as neuroinflammation, low levels of neurogenesis, disrupted blood–brain barrier and altered neuronal activity, might lead to structural and functional rejuvenation of the aged brain. Here we show that a 6-week treatment of young (4 months) and old (20 months) rats with montelukast, a marketed anti-asthmatic drug antagonizing leukotriene receptors, reduces neuroinflammation, elevates hippocampal neurogenesis and improves learning and memory in old animals. By using gene knockdown and knockout approaches, we demonstrate that the effect is mediated through inhibition of the GPR17 receptor. This work illustrates that inhibition of leukotriene receptor signalling might represent a safe and druggable target to restore cognitive functions in old individuals and paves the way for future clinical translation of leukotriene receptor inhibition for the treatment of dementias. PMID:26506265

  8. Accelerating aging of zirconia femoral head implants: change of surface structure and mechanical properties.

    PubMed

    Chowdhury, S; Vohra, Yogesh K; Lemons, Jack E; Ueno, Masaru; Ikeda, Junji

    2007-05-01

    Recently, alternations of zirconia ceramic femoral heads of total hip prostheses during in vivo conditions have caused concern in the medical disciplines regarding phase transformation of zirconia prosthetic components. In this paper, we have investigated the mechanical and structural properties of different laboratory aged zirconia femoral heads and correlated changes in mechanical properties with the phase compositions of the sample. From laser microscope observation, cross-sectional Scanning electron microscopy imaging, and X-ray diffraction analysis on the surface of the zirconia femoral heads, we found monoclinic to tetragonal phase transformation in zirconia prostheses over time during the aging process in the laboratory. Mechanical properties, mainly hardness (H) and Young's modulus (E) values, were measured by nanoindentation technique on the surface of these implants. The results showed that both H and E values decreased with increased monoclinic phase in zirconia, thus confirming a phase transformation over time during aging.

  9. Structural and functional rejuvenation of the aged brain by an approved anti-asthmatic drug.

    PubMed

    Marschallinger, Julia; Schäffner, Iris; Klein, Barbara; Gelfert, Renate; Rivera, Francisco J; Illes, Sebastian; Grassner, Lukas; Janssen, Maximilian; Rotheneichner, Peter; Schmuckermair, Claudia; Coras, Roland; Boccazzi, Marta; Chishty, Mansoor; Lagler, Florian B; Renic, Marija; Bauer, Hans-Christian; Singewald, Nicolas; Blümcke, Ingmar; Bogdahn, Ulrich; Couillard-Despres, Sebastien; Lie, D Chichung; Abbracchio, Maria P; Aigner, Ludwig

    2015-01-01

    As human life expectancy has improved rapidly in industrialized societies, age-related cognitive impairment presents an increasing challenge. Targeting histopathological processes that correlate with age-related cognitive declines, such as neuroinflammation, low levels of neurogenesis, disrupted blood-brain barrier and altered neuronal activity, might lead to structural and functional rejuvenation of the aged brain. Here we show that a 6-week treatment of young (4 months) and old (20 months) rats with montelukast, a marketed anti-asthmatic drug antagonizing leukotriene receptors, reduces neuroinflammation, elevates hippocampal neurogenesis and improves learning and memory in old animals. By using gene knockdown and knockout approaches, we demonstrate that the effect is mediated through inhibition of the GPR17 receptor. This work illustrates that inhibition of leukotriene receptor signalling might represent a safe and druggable target to restore cognitive functions in old individuals and paves the way for future clinical translation of leukotriene receptor inhibition for the treatment of dementias. PMID:26506265

  10. Fine structural changes in the lateral vestibular nucleus of aging rats

    NASA Technical Reports Server (NTRS)

    Johnson, J. E., Jr.; Miquel, J.

    1974-01-01

    The fine structure of the lateral vestibular nucleus was investigated in Sprague-Dawley rats, that were sacrified at 4 weeks, 6-8 weeks, 6-8 months, and 18-20 months of age. In the neuronal perikaria, the following age-associated changes were seen with increasing frequency with advancing age: rodlike nuclear inclusions and nuclear membrane invaginations; cytoplasmic dense bodies with the characteristics of lipofuscin; and moderate disorganization of the granular endoplasmic reticulum. Dense bodies were also seen in glial cells. Rats 18 to 20 months old showed dendritic swellings, axonal degeneration, and an apparent increase in the number of axosomatic synaptic terminals containing flattened vesicles (presumed to be inhibitory in function).

  11. The Canalicular Structure of Compact Bone in the Rat at Different Ages

    NASA Astrophysics Data System (ADS)

    Okada, Shigenori; Yoshida, Shigemitsu; Ashrafi, Shahid H.; Schraufnagel, Dean E.

    2002-04-01

    Osteocytes communicate through a canalicular system that maintains the vitality and mineral metabolism of bone. Casting the vascular canals and canaliculi of compact bone with methacrylate and viewing them with scanning electron microscopy shows their extent and relationships. Confocal laser scanning microscopy of the same specimen before corrosion establishes the degree of calcification of the different tissue components. These methods were used to compare basal with alveolar compact bone in the rat mandible at different ages. Sections of the mandibular molar region were placed in a methacrylate resin. After polymerization and study with confocal microscopy, the organic matrix was removed. Juvenile rats had large irregular central vascular canals and lacunae that were more concentric in the basal than the alveolar bone. Cast lacunae were round, and the canaliculi from these lacunae were short and thick in both bones. Adult rats had regular concentrically arranged lacunae in the basal bone. Cast lacunae were ellipsoid and flatter in the basal bone than in the alveolar bone. The intercommunicating canaliculi were increased and canaliculi had more branching than the juvenile rats. The aged rats had fewer vascular canals, lacunae, and canaliculi and had osteoporotic changes. The cast lacunae were slender and flat especially in the basal bone. The porosity of the mandible became more pronounced in the alveolar than in the basal bone with aging. The canaliculi of mandibular compact bone thinned and developed extensive branching with adulthood but decreased in size and number with advanced age. Lacunae proceed from the large circular structures of youth to the flat forms of the aged. These studies show that the internal structure of compact bone changes with age and mirrors its functional state.

  12. Surface structural changes of naturally aged silicone and EPDM composite insulators

    SciTech Connect

    Vlastos, A.E. ); Gubanski, S.M. )

    1991-04-01

    In a long-term outdoor test with high direct and alternating voltages, silicone and EPDM rubber composite insulators have, at the beginning, shown a superior performance to that of glass and porcelain insulators. In the long-term test, however, the silicone rubber composite insulator has, in spite of the ageing of both insulator types, kept its good performance, while the performance of the EPDM rubber composite insulator was drastically deteriorated. In order to get a better insight into results obtained, the wettability and the surface structural changes of the insulators were studied by the drop deposition method (using a goniometer) and by advanced techniques such as SEM, ESCA, FTIR and SIMS respectively. The results show that the differences in performance have to be found in the differences in the surface structural changes and in the dynamic ability of the surface to compensate the ageing.

  13. DETERMINING THE EFFECTS OF RADIATION ON AGING CONCRETE STRUCTURES OF NUCLEAR REACTORS

    SciTech Connect

    Serrato, M.

    2010-01-29

    The U.S. Department of Energy Office of Environmental Management (DOE-EM) is responsible for the Decontamination and Decommissioning (D&D) of nuclear facilities throughout the DOE Complex. Some of these facilities will be completely dismantled, while others will be partially dismantled and the remaining structure will be stabilized with cementitious fill materials. The latter is a process known as In-Situ Decommissioning (ISD). The ISD decision process requires a detailed understanding of the existing facility conditions, and operational history. System information and material properties are need for aged nuclear facilities. This literature review investigated the properties of aged concrete structures affected by radiation. In particular, this review addresses the Savannah River Site (SRS) isotope production nuclear reactors. The concrete in the reactors at SRS was not seriously damaged by the levels of radiation exposure. Loss of composite compressive strength was the most common effect of radiation induced damage documented at nuclear power plants.

  14. Structural patterns of the proximal femur in relation to age and hip fracture risk in women.

    PubMed

    Carballido-Gamio, Julio; Harnish, Roy; Saeed, Isra; Streeper, Timothy; Sigurdsson, Sigurdur; Amin, Shreyasee; Atkinson, Elizabeth J; Therneau, Terry M; Siggeirsdottir, Kristin; Cheng, Xiaoguang; Melton, L Joseph; Keyak, Joyce H; Gudnason, Vilmundur; Khosla, Sundeep; Harris, Tamara B; Lang, Thomas F

    2013-11-01

    Fractures of the proximal femur are the most devastating outcome of osteoporosis. It is generally understood that age-related changes in hip structure confer increased risk, but there have been few explicit comparisons of such changes in healthy subjects to those with hip fracture. In this study, we used quantitative computed tomography and tensor-based morphometry (TBM) to identify three-dimensional internal structural patterns of the proximal femur associated with age and with incident hip fracture. A population-based cohort of 349 women representing a broad age range (21-97years) was included in this study, along with a cohort of 222 older women (mean age 79±7years) with (n=74) and without (n=148) incident hip fracture. Images were spatially normalized to a standardized space, and age- and fracture-specific morphometric features were identified based on statistical maps of shape features described as local changes of bone volume. Morphometric features were visualized as maps of local contractions and expansions, and significance was displayed as Student's t-test statistical maps. Significant age-related changes included local expansions of regions low in volumetric bone mineral density (vBMD) and local contractions of regions high in vBMD. Some significant fracture-related features resembled an accentuated aging process, including local expansion of the superior aspect of the trabecular bone compartment in the femoral neck, with contraction of the adjoining cortical bone. However, other features were observed only in the comparison of hip fracture subjects with age-matched controls including focal contractions of the cortical bone at the superior aspect of the femoral neck, the lateral cortical bone just inferior to the greater trochanter, and the anterior intertrochanteric region. Results of this study support the idea that the spatial distribution of morphometric features is relevant to age-related changes in bone and independent to fracture risk. In women

  15. Estimating the age of stone structures using OSL: the potential of entrapped sediment

    NASA Astrophysics Data System (ADS)

    Baran, J.; Murray, A. S.; Häggström, L.

    2003-05-01

    We report on the potential of using optically stimulated luminescence (OSL) to determine the construction age of various stone structures at an archaeological site at Öggestorp, near Jönköping in southern Sweden. The sediment filling the interstices between stones in a wall and a clearance cairn is assumed to have been light exposed during or before construction, and we anticipated that these fill samples were likely to be incompletely bleached, so that the smallest doses would be the most relevant. However, any reworking of the structures, or even later aeolian events, could emplace a small fraction of younger materials, and so there were also likely to be some grains with substantially smaller doses. The dose distributions from such fill samples have been studied using both small aliquots and individual grains of quartz. We present preliminary construction ages for a stone wall and cairn based on these dose distributions, and compare these with independent age constraints derived from OSL ages of associated heated stones and aeolian sand, and from the other archaeological evidence.

  16. Optimal Harvesting in an Age-Structured Predator-Prey Model

    SciTech Connect

    Fister, K. Renee Lenhart, Suzanne

    2006-06-15

    We investigate optimal harvesting control in a predator-prey model in which the prey population is represented by a first-order partial differential equation with age-structure and the predator population is represented by an ordinary differential equation in time. The controls are the proportions of the populations to be harvested, and the objective functional represents the profit from harvesting. The existence and uniqueness of the optimal control pair are established.

  17. Nuclei of aged myofibres undergo structural and functional changes suggesting impairment in RNA processing

    PubMed Central

    Malatesta, M.; Perdoni, F.; Muller, S.; Zancanaro, C.; Pellicciari, C.

    2009-01-01

    Advancing adult age is associated with a progressive decrease in skeletal muscle mass, strength and quality known as sarcopenia. The mechanisms underlying age-related skeletal muscle wasting and weakness are manifold and still remain to be fully elucidated. Despite the increasing evidence that the progress of muscle diseases leading to muscle atrophy/dystrophy may be related to defective RNA processing, no data on the morpho-functional features of skeletal muscle nuclei in sarcopenia are available at present. In this view, we have investigated, by combining morphometry and immunocytochemistry at light and electron microscopy, the fine structure of myonuclei as well as the distribution and amount of RNA processing factors in skeletal myofibres of biceps brachii and quadriceps femoris from adult and old rats. Results demonstrate that the myonuclei of aged type II fibres show an increased amount of condensed chromatin and lower amounts of phosphorylated polymerase II and DNA/RNA hybrid molecules, clearly indicating a decrease in pre-mRNA transcription rate compared to adult animals. In addition, myonuclei of aged fibres show decreased amounts of nucleoplasmic splicing factors and an accumulation of cleavage factors, polyadenilated RNA and perichromatin granules, suggesting a reduction in the processing and transport rate of pre-mRNA. During ageing, it seems therefore that in rat myonuclei the entire production chain of mRNA, from synthesis to cytoplasmic export, is less efficient. This failure likely contributes to the reduced responsiveness of muscle cells to anabolic stimuli in the elderly.

  18. Ageing increases reliance on sensorimotor prediction through structural and functional differences in frontostriatal circuits

    PubMed Central

    Wolpe, Noham; Ingram, James N.; Tsvetanov, Kamen A.; Geerligs, Linda; Kievit, Rogier A.; Henson, Richard N.; Wolpert, Daniel M.; Tyler, Lorraine K.; Brayne, Carol; Bullmore, Edward; Calder, Andrew; Cusack, Rhodri; Dalgleish, Tim; Duncan, John; Matthews, Fiona E.; Marslen-Wilson, William; Shafto, Meredith A.; Campbell, Karen; Cheung, Teresa; Davis, Simon; McCarrey, Anna; Mustafa, Abdur; Price, Darren; Samu, David; Taylor, Jason R.; Treder, Matthias; van Belle, Janna; Williams, Nitin; Bates, Lauren; Emery, Tina; Erzinçlioglu, Sharon; Gadie, Andrew; Gerbase, Sofia; Georgieva, Stanimira; Hanley, Claire; Parkin, Beth; Troy, David; Auer, Tibor; Correia, Marta; Gao, Lu; Green, Emma; Henriques, Rafael; Allen, Jodie; Amery, Gillian; Amunts, Liana; Barcroft, Anne; Castle, Amanda; Dias, Cheryl; Dowrick, Jonathan; Fair, Melissa; Fisher, Hayley; Goulding, Anna; Grewal, Adarsh; Hale, Geoff; Hilton, Andrew; Johnson, Frances; Johnston, Patricia; Kavanagh-Williamson, Thea; Kwasniewska, Magdalena; McMinn, Alison; Norman, Kim; Penrose, Jessica; Roby, Fiona; Rowland, Diane; Sargeant, John; Squire, Maggie; Stevens, Beth; Stoddart, Aldabra; Stone, Cheryl; Thompson, Tracy; Yazlik, Ozlem; Barnes, Dan; Dixon, Marie; Hillman, Jaya; Mitchell, Joanne; Villis, Laura; Rowe, James B.

    2016-01-01

    The control of voluntary movement changes markedly with age. A critical component of motor control is the integration of sensory information with predictions of the consequences of action, arising from internal models of movement. This leads to sensorimotor attenuation—a reduction in the perceived intensity of sensations from self-generated compared with external actions. Here we show that sensorimotor attenuation occurs in 98% of adults in a population-based cohort (n=325; 18–88 years; the Cambridge Centre for Ageing and Neuroscience). Importantly, attenuation increases with age, in proportion to reduced sensory sensitivity. This effect is associated with differences in the structure and functional connectivity of the pre-supplementary motor area (pre-SMA), assessed with magnetic resonance imaging. The results suggest that ageing alters the balance between the sensorium and predictive models, mediated by the pre-SMA and its connectivity in frontostriatal circuits. This shift may contribute to the motor and cognitive changes observed with age. PMID:27694879

  19. Damage from periorbital ageing to the multilayered structures and resilience of the skin in Chinese population

    PubMed Central

    Liao, Chuh-Kai; Tsai, Feng-Chou; Fong, Tsorng-Harn; Hu, Chien-Ming; Wei, Po-Li; Su, Ching-Hua

    2013-01-01

    Ageing dynamically disrupts the multilayered supporting components of the skin that are held together by cell adhesion molecules (CAMs). Skin specimens from 33 female Chinese patients undergoing lower blepharoplasty were divided into three age groups and examined by haematoxylin and eosin (H&E) staining, immunohistochemistry (IHC) and Elastica-van Gieson (EVG) stains, western blotting, surface electron microscopy (SEM) and biomechanical tension analysis. The SEM density (skin surface topology) showed a negative linear relationship with age. The triangular pattern of the skin surface in the younger group gradually broke down into quadrangular and irregular patterns in the older group. Collagens and elastic fibres in the dermis showed anisotropy and decreased density in the older groups compared with the younger group, especially in the papillary dermis. Anisotropy means that physical properties differ according to the direction of measurement. E-cadherin and integrin αv (whose functions are to bind epidermal and dermal elements respectively) increased and decreased, respectively, in the oldest group. Skin resilience decreased significantly in this group under repetitive stress. In conclusion, a loss of skin surface textures, integrin αv expressions, epidermal-dermal connections and dermal compactness led to the multilayered structure of the skin becoming separated. This in turn decreased resilience during ageing. These findings may therefore explain why aged skins cannot tolerate repetitive facial expressions, and why this action produces further dynamic wrinkles. PMID:23441675

  20. Graphical and Demographic Synopsis of the Captive Cohort Method for Estimating Population Age Structure in the Wild

    PubMed Central

    Carey, James R.; Müller, Hans-Georg; Wang, Jane-Ling; Papadopoulos, Nikos; Diamantidis, Alexis; Kouloussis, Nikos

    2014-01-01

    The purpose of this paper is to complement the literature concerned with the captive cohort method for estimating age structure including (1) graphic techniques to visualize and thus better understand the underlying life table identity in which the age structure of a stationary population equals the time-to-death distribution of the individuals within it; (2) re-derive the basic model for estimating age structure in non-stationary population in demographic rather than statistical notation; and (3) describe a simplified method for estimating changes in the mean age of a wild population. PMID:22776134

  1. Structural response of phyllomanganates to wet aging and aqueous Mn(II)

    NASA Astrophysics Data System (ADS)

    Hinkle, Margaret A. G.; Flynn, Elaine D.; Catalano, Jeffrey G.

    2016-11-01

    Naturally occurring Mn(IV/III) oxides are often formed through microbial Mn(II) oxidation, resulting in reactive phyllomanganates with varying Mn(IV), Mn(III), and vacancy contents. Residual aqueous Mn(II) may adsorb in the interlayer of phyllomanganates above vacancies in their octahedral sheets. The potential for interlayer Mn(II)-layer Mn(IV) comproportionation reactions and subsequent formation of structural Mn(III) suggests that aqueous Mn(II) may cause phyllomanganate structural changes that alters mineral reactivity or trace metal scavenging. Here we examine the effects of aging phyllomanganates with varying initial vacancy and Mn(III) content in the presence and absence of dissolved Mn(II) at pH 4 and 7. Three phyllomanganates were studied: two exhibiting turbostratic layer stacking (δ-MnO2 with high vacancy content and hexagonal birnessite with both vacancies and Mn(III) substitutions) and one with rotationally ordered layer stacking (triclinic birnessite containing predominantly Mn(III) substitutions). Structural analyses suggest that during aging at pH 4, Mn(II) adsorbs above vacancies and promotes the formation of phyllomanganates with rotationally ordered sheets and mixed symmetries arranged into supercells, while structural Mn(III) undergoes disproportionation. These structural changes at pH 4 correlate with reduced Mn(II) uptake onto triclinic and hexagonal birnessite after 25 days relative to 48 h of reaction, indicating that phyllomanganate reactivity decreases upon aging with Mn(II), or that recrystallization processes involving Mn(II) uptake occur over 25 days. At pH 7, Mn(II) adsorbs and causes limited structural effects, primarily increasing sheet stacking in δ-MnO2. These results show that aging-induced structural changes in phyllomanganates are affected by aqueous Mn(II), pH, and initial solid-phase Mn(III) content. Such restructuring likely alters manganese oxide reactions with other constituents in environmental and geologic systems

  2. The effect of age on the structural properties of human ribs.

    PubMed

    Agnew, Amanda M; Schafman, Michelle; Moorhouse, Kevin; White, Susan E; Kang, Yun-Seok

    2015-01-01

    Traumatic injury from motor vehicle crashes is a major cause of morbidity and mortality in the United States. The thorax is particularly at risk in motor vehicle crashes and is studied extensively by the injury biomechanics community. Unfortunately, most samples used in such research generally do not include children or the very elderly, despite the common occurrence of thorax injuries at both ends of the age spectrum. Rib fractures in particular, are one of the most common injuries, especially in the elderly, and can greatly affect morbidity, mortality, and quality of life. As the proportion of older adults in the population increases, such age-related fragility fractures will continually grow as a worldwide problem. Additionally, the risk of rib fracture significantly increases with age with confounding deleterious effects. Studies on elderly ribs are not uncommon, however very few studies exist which explore the mechanical properties and behavior of immature human bone, especially of ribs. Previous research identifying rib properties has provided useful information for numerous applications. However, no study has included a comprehensive sample of all ages (pediatric through elderly) in which ribs are tested in the same repeatable set-up. The goal of this study is to characterize differences in rib structural response across the age spectrum. One-hundred forty excised ribs from 70 individuals were experimentally tested in a custom-built pendulum fixture simulating a dynamic frontal impact. The sample includes individuals of ages ranging from six to 99 years old and includes 58 males and 12 females. Reported data include fracture location, displacement in the X and Y directions at fracture (δX, δY), force at fracture (FX), and linear structural stiffness (K). δX and K exhibit a statistically significant linear decrease with age (p<0.0001). FX reveals a trend in which a peak is reached in the young adult years (25-40). Detailed mechanical property data, as

  3. Assessing Defense Structure in School-Age Children Using the Response Evaluation Measure-71-Youth Version (REM-Y-71)

    ERIC Educational Resources Information Center

    Araujo, Katy B.; Medic, Sanja; Yasnovsky, Jessica; Steiner, Hans

    2006-01-01

    This study used the Response Evaluation Measure-Youth (REM-Y-71), a self-report measure of 21 defense reactions, among school-age children. Participants were elementary and middle school students (n=290; grades 3-8; age range: 8-15; mean=11.73). Factor analysis revealed a 2-factor defense structure consistent with structure among high school and…

  4. Influence of aging temperature on the structure and mechanical properties of titanium alloy VT22 subjected to helical rolling

    NASA Astrophysics Data System (ADS)

    Mishin, I. P.; Naydenkin, E. V.; Ratochka, I. V.; Lykova, O. N.; Balushkina, M. A.

    2015-10-01

    The structure and mechanical properties of titanium alloy VT22 after helical rolling and subsequent aging was investigated. It is shown that the treatment leads to the formation of ultra-fine grain/subgrain structure in the alloy. The subsequent aging increases the ultimate strength and yield strength to 1640 and 1590 MPa respectively, while saving satisfactory plasticity (δ > 5%).

  5. Solar abundance of osmium

    PubMed Central

    Jacoby, George; Aller, Lawrence H.

    1976-01-01

    The abundance parameter, log gfA, where g is the statistical weight of the lower level, f is the oscillator strength, and A is the abundance (by numbers of atoms with respect to hydrogen), has been derived for three lines of osmium by a method of spectrum synthesis. An apparent discordance of the derived abundance with that found from the carbonaceous chondrites is probably to be attributed primarily to errors in the f-values, and blending with unknown contributors. PMID:16592314

  6. Social Structural Influences on Healthy Aging: Community-Level Socioeconomic Conditions and Survival Probability of Becoming a Centenarian for Those Aged 65 to 69 in South Korea.

    PubMed

    Kim, Jong In; Kim, Gukbin

    2015-10-01

    This study estimated the associations between community-level socioeconomic conditions and survival probability of becoming a centenarian (SPBC) for those aged 65 to 69 in South Korea to determine the social structural influences on healthy aging. The indicators of socioeconomic and data of centenarians were obtained from Statistics Korea database 2014: population census and social survey. Significant positive correlations were found between SPBC and community-level socioeconomic conditions (minimum cost of living and economically active population, water supply and sewerage, pave a road with asphalt, and urbanization). SPBC male and female predictors had higher economic level and base facilities (R2)=0.578, p<.001). The study provides evidence that community-level socioeconomic conditions are important correlates of SPBC for those aged 65 to 69 in South Korea. These strategies should include social structural influences on successful aging in the overall socioeconomic conditions. PMID:26769915

  7. Social Structural Influences on Healthy Aging: Community-Level Socioeconomic Conditions and Survival Probability of Becoming a Centenarian for Those Aged 65 to 69 in South Korea.

    PubMed

    Kim, Jong In; Kim, Gukbin

    2015-10-01

    This study estimated the associations between community-level socioeconomic conditions and survival probability of becoming a centenarian (SPBC) for those aged 65 to 69 in South Korea to determine the social structural influences on healthy aging. The indicators of socioeconomic and data of centenarians were obtained from Statistics Korea database 2014: population census and social survey. Significant positive correlations were found between SPBC and community-level socioeconomic conditions (minimum cost of living and economically active population, water supply and sewerage, pave a road with asphalt, and urbanization). SPBC male and female predictors had higher economic level and base facilities (R2)=0.578, p<.001). The study provides evidence that community-level socioeconomic conditions are important correlates of SPBC for those aged 65 to 69 in South Korea. These strategies should include social structural influences on successful aging in the overall socioeconomic conditions.

  8. The Formation, Structure, and Ageing of As-Rich Hydrous Ferric Oxide at the Abandoned Sb Deposit Pezinok (Slovakia)

    SciTech Connect

    Majzlan,J.; Lalinska, B.; Chovan, M.; Jurkovic, L.; Milovska, S.; Gottlicher, J.

    2007-01-01

    The abandoned Sb deposit Pezinok in Slovakia is a significant source of As and Sb pollution that can be traced in the upper horizons of soils kilometers downstream. The source of the metalloids are two tailing impoundments which hold {approx}380,000 m{sup 3} of mining waste. The tailings and the discharged water have circumneutral pH values (7.0 {+-} 0.6) because the acidity generated by the decomposition of the primary sulfides (pyrite, FeS{sub 2}; arsenopyrite, FeAsS; berthierite, FeSb{sub 2}S{sub 4}) is rapidly neutralized by the abundant carbonates. The weathering rims on the primary sulfides are iron oxides which act as very efficient scavengers of As and Sb (with up to 19.2 wt% As and 23.7 wt% Sb). In-situ {mu}-XANES experiments indicate that As in the weathering rims is fully oxidized (As{sup 5+}). The pore solutions in the impoundment body contain up to 81 ppm As and 2.5 ppm Sb. Once these solutions are discharged from the impoundments, they precipitate or deposit masses of As-rich hydrous ferric oxide (As-HFO) with up to 28.3 wt% As{sub 2}O{sub 5} and 2.7 wt% Sb. All As-HFO samples are amorphous to X-rays. They contain Fe and As in their highest oxidation state and in octahedral and tetrahedral coordination, respectively, as suggested by XANES and EXAFS studies on Fe K and As K edges. The iron octahedra in the As-HFO share edges to form short single chains and the chains polymerize by sharing edges or corners with the adjacent units. The arsenate ions attach to the chains in a bidentate-binuclear and monodentate fashion. In addition, hydrogen-bonded complexes may exist to satisfy the bonding requirements of all oxygen atoms in the first coordination sphere of As{sup 5+}. Structural changes in the As-HFO samples were traced by chemical analyses and Fe EXAFS spectroscopy during an ageing experiment. As the samples age, As becomes more easily leachable. EXAFS spectra show a discernible trend of increasing number of Fe-Fe pairs at a distance of 3

  9. [Physicians and surgeons in Saragossa during the modern age. Number, social and family structure].

    PubMed

    Fernandez Doctor, A

    1997-01-01

    Documentation at the College of Physicians and Surgeons of Saragossa, scattered throughout many archives, made it possible to trace the evolution of the number of physicians and surgeons in the city of Saragossa in the Modern Age with regard to the number of inhabitants of this city. Also studied are the possible causes of increases or decreases in their numbers, and the proportions of physicians and surgeons to inhabitants are compared with figures from other Spanish regions. By studying a 1723 census, the social and family structures of the different health professions in Saragossa are analyzed. Comparisons of these figures to the structures of other professions made it possible to determine the different social level of each structure. The social level of physicians was the same as that of apothecaries, whereas it was higher than that of surgeons and veterinarians and lower than that of legal professionals, notaries and jurists.

  10. Mössbauer study of two different aged rock types in the Vredefort structure, South Africa

    NASA Astrophysics Data System (ADS)

    Waanders, F. B.; Brink, M. C.; Bisschoff, A. A.

    2005-11-01

    The Vredefort Structure in South Africa was recently inscribed into the list of World Heritage sites as the oldest and largest recognised impact structure on earth. Due to upliftment of more than 30 km of the Archaean basement core and subsequent exposure of the deeply eroded central portion of the crater a unique opportunity exists to study rocks of the crust, especially those that have undergone recrystallization due to various thermal metamorphic events over time. Two rock types occurring in the central uplifted part of the impact structure were studied. One was a typical Archaean iron formation of sedimentary origin. The other rock studied, adjacent to this much older rock, is a homogeneous, medium grained recrystallized norite of immediately pre- or post-impact age, indicating a possible mafic igneous activity related to impact. Microscopy, XRD and Mössbauer analyses were performed on both samples.

  11. Abundance and Distribution of Dimethylsulfoniopropionate Degradation Genes and the Corresponding Bacterial Community Structure at Dimethyl Sulfide Hot Spots in the Tropical and Subtropical Pacific Ocean

    PubMed Central

    Suzuki, Shotaro; Omori, Yuko; Wong, Shu-Kuan; Ijichi, Minoru; Kaneko, Ryo; Kameyama, Sohiko; Tanimoto, Hiroshi; Hamasaki, Koji

    2015-01-01

    Dimethylsulfoniopropionate (DMSP) is mainly produced by marine phytoplankton but is released into the microbial food web and degraded by marine bacteria to dimethyl sulfide (DMS) and other products. To reveal the abundance and distribution of bacterial DMSP degradation genes and the corresponding bacterial communities in relation to DMS and DMSP concentrations in seawater, we collected surface seawater samples from DMS hot spot sites during a cruise across the Pacific Ocean. We analyzed the genes encoding DMSP lyase (dddP) and DMSP demethylase (dmdA), which are responsible for the transformation of DMSP to DMS and DMSP assimilation, respectively. The averaged abundance (±standard deviation) of these DMSP degradation genes relative to that of the 16S rRNA genes was 33% ± 12%. The abundances of these genes showed large spatial variations. dddP genes showed more variation in abundances than dmdA genes. Multidimensional analysis based on the abundances of DMSP degradation genes and environmental factors revealed that the distribution pattern of these genes was influenced by chlorophyll a concentrations and temperatures. dddP genes, dmdA subclade C/2 genes, and dmdA subclade D genes exhibited significant correlations with the marine Roseobacter clade, SAR11 subgroup Ib, and SAR11 subgroup Ia, respectively. SAR11 subgroups Ia and Ib, which possessed dmdA genes, were suggested to be the main potential DMSP consumers. The Roseobacter clade members possessing dddP genes in oligotrophic subtropical regions were possible DMS producers. These results suggest that DMSP degradation genes are abundant and widely distributed in the surface seawater and that the marine bacteria possessing these genes influence the degradation of DMSP and regulate the emissions of DMS in subtropical gyres of the Pacific Ocean. PMID:25862229

  12. Abundance and distribution of dimethylsulfoniopropionate degradation genes and the corresponding bacterial community structure at dimethyl sulfide hot spots in the tropical and subtropical pacific ocean.

    PubMed

    Cui, Yingshun; Suzuki, Shotaro; Omori, Yuko; Wong, Shu-Kuan; Ijichi, Minoru; Kaneko, Ryo; Kameyama, Sohiko; Tanimoto, Hiroshi; Hamasaki, Koji

    2015-06-15

    Dimethylsulfoniopropionate (DMSP) is mainly produced by marine phytoplankton but is released into the microbial food web and degraded by marine bacteria to dimethyl sulfide (DMS) and other products. To reveal the abundance and distribution of bacterial DMSP degradation genes and the corresponding bacterial communities in relation to DMS and DMSP concentrations in seawater, we collected surface seawater samples from DMS hot spot sites during a cruise across the Pacific Ocean. We analyzed the genes encoding DMSP lyase (dddP) and DMSP demethylase (dmdA), which are responsible for the transformation of DMSP to DMS and DMSP assimilation, respectively. The averaged abundance (±standard deviation) of these DMSP degradation genes relative to that of the 16S rRNA genes was 33% ± 12%. The abundances of these genes showed large spatial variations. dddP genes showed more variation in abundances than dmdA genes. Multidimensional analysis based on the abundances of DMSP degradation genes and environmental factors revealed that the distribution pattern of these genes was influenced by chlorophyll a concentrations and temperatures. dddP genes, dmdA subclade C/2 genes, and dmdA subclade D genes exhibited significant correlations with the marine Roseobacter clade, SAR11 subgroup Ib, and SAR11 subgroup Ia, respectively. SAR11 subgroups Ia and Ib, which possessed dmdA genes, were suggested to be the main potential DMSP consumers. The Roseobacter clade members possessing dddP genes in oligotrophic subtropical regions were possible DMS producers. These results suggest that DMSP degradation genes are abundant and widely distributed in the surface seawater and that the marine bacteria possessing these genes influence the degradation of DMSP and regulate the emissions of DMS in subtropical gyres of the Pacific Ocean.

  13. Age of language learning shapes brain structure: a cortical thickness study of bilingual and monolingual individuals.

    PubMed

    Klein, Denise; Mok, Kelvin; Chen, Jen-Kai; Watkins, Kate E

    2014-04-01

    We examined the effects of learning a second language (L2) on brain structure. Cortical thickness was measured in the MRI datasets of 22 monolinguals and 66 bilinguals. Some bilingual subjects had learned both languages simultaneously (0-3 years) while some had learned their L2 after achieving proficiency in their first language during either early (4-7 years) or late childhood (8-13 years). Later acquisition of L2 was associated with significantly thicker cortex in the left inferior frontal gyrus (IFG) and thinner cortex in the right IFG. These effects were seen in the group comparisons of monolinguals, simultaneous bilinguals and early and late bilinguals. Within the bilingual group, significant correlations between age of acquisition of L2 and cortical thickness were seen in the same regions: cortical thickness correlated with age of acquisition positively in the left IFG and negatively in the right IFG. Interestingly, the monolinguals and simultaneous bilinguals did not differ in cortical thickness in any region. Our results show that learning a second language after gaining proficiency in the first language modifies brain structure in an age-dependent manner whereas simultaneous acquisition of two languages has no additional effect on brain development. PMID:23819901

  14. Gene-drive into insect populations with age and spatial structure: a theoretical assessment.

    PubMed

    Huang, Yunxin; Lloyd, Alun L; Legros, Mathieu; Gould, Fred

    2011-05-01

    The potential benefits and risks of genetically engineered gene-drive systems for replacing wild pest strains with more benign strains must be assessed prior to any field releases. We develop a computer simulation model to assess the feasibility of using engineered underdominance constructs to drive transgenes into age- and spatially structured mosquito populations. Our practical criterion for success is the achievement of a transgene frequency of at least 0.80 within 3 years of release. The impacts of a number of parameters that may affect the success of gene-drive, such as the release area, release age, density-dependent larval survival, fitness cost of the engineered genes, and migration probability of adults, are examined. Results show that patchy release generally requires the release of fewer engineered insects to achieve success than central release. When the fitness cost is very low, central release covering 25% of the total area can be more effective than a completely uniform release over the whole area. This study demonstrates that to determine the best method of spatial release, and the total number of engineered insects that must be released, it is important to take into account the age and sex of the released insects and spatial structure of the population.

  15. Fine resolution mapping of population age-structures for health and development applications

    PubMed Central

    Alegana, V. A.; Atkinson, P. M.; Pezzulo, C.; Sorichetta, A.; Weiss, D.; Bird, T.; Erbach-Schoenberg, E.; Tatem, A. J.

    2015-01-01

    The age-group composition of populations varies considerably across the world, and obtaining accurate, spatially detailed estimates of numbers of children under 5 years is important in designing vaccination strategies, educational planning or maternal healthcare delivery. Traditionally, such estimates are derived from population censuses, but these can often be unreliable, outdated and of coarse resolution for resource-poor settings. Focusing on Nigeria, we use nationally representative household surveys and their cluster locations to predict the proportion of the under-five population in 1 × 1 km using a Bayesian hierarchical spatio-temporal model. Results showed that land cover, travel time to major settlements, night-time lights and vegetation index were good predictors and that accounting for fine-scale variation, rather than assuming a uniform proportion of under 5 year olds can result in significant differences in health metrics. The largest gaps in estimated bednet and vaccination coverage were in Kano, Katsina and Jigawa. Geolocated household surveys are a valuable resource for providing detailed, contemporary and regularly updated population age-structure data in the absence of recent census data. By combining these with covariate layers, age-structure maps of unprecedented detail can be produced to guide the targeting of interventions in resource-poor settings. PMID:25788540

  16. Age of language learning shapes brain structure: a cortical thickness study of bilingual and monolingual individuals.

    PubMed

    Klein, Denise; Mok, Kelvin; Chen, Jen-Kai; Watkins, Kate E

    2014-04-01

    We examined the effects of learning a second language (L2) on brain structure. Cortical thickness was measured in the MRI datasets of 22 monolinguals and 66 bilinguals. Some bilingual subjects had learned both languages simultaneously (0-3 years) while some had learned their L2 after achieving proficiency in their first language during either early (4-7 years) or late childhood (8-13 years). Later acquisition of L2 was associated with significantly thicker cortex in the left inferior frontal gyrus (IFG) and thinner cortex in the right IFG. These effects were seen in the group comparisons of monolinguals, simultaneous bilinguals and early and late bilinguals. Within the bilingual group, significant correlations between age of acquisition of L2 and cortical thickness were seen in the same regions: cortical thickness correlated with age of acquisition positively in the left IFG and negatively in the right IFG. Interestingly, the monolinguals and simultaneous bilinguals did not differ in cortical thickness in any region. Our results show that learning a second language after gaining proficiency in the first language modifies brain structure in an age-dependent manner whereas simultaneous acquisition of two languages has no additional effect on brain development.

  17. Atomic structure of Cu-10. 9 at % Be alloys in the early stages of aging

    SciTech Connect

    Koo, Y.M.

    1987-01-01

    Diffuse x-ray scattering was employed to investigate the local atomic structure and static strains in a single crystal of a Cu-10.9 at. % Be alloy in the early stages of aging. In addition to these experiments, neutron elastic and inelastic scattering were obtained to investigate the phonon properties in the as-quenched state of this alloy. In the as-quenched state, there is a nearly regular array of small ellipsoidal Be clusters aligned along <100> directions (This produces the tweed contrast seen in TEM). The density of these clusters is 7.5 x 10/sup 26//m/sup 3/. The diffuse streaks seen in electron diffraction patterns are due largely to thermal diffuse scattering. Phonon-dispersion curves show no large differences from those of pure copper, except at (xi xi xi)/sub T/ zone boundary, where there is softening. This difference may be due to a Kohn anomaly. The elastic anisotropy of this alloy increases considerably with alloying, which probably leads to the plate-like GP zone morphology in subsequent aging treatments. The structure of the GP zones is a mixture of Be-rich single- and multi-layered zones. As aging proceeds, the zones grow in thickness.

  18. All together now? Sensitivity, dynamics, and predictability of planktonic foraminiferal species abundance versus community structure across Plio-Pleistocene glacial-interglacial cycles

    NASA Astrophysics Data System (ADS)

    Hull, P. M.; Norris, R. D.; Sexton, P.

    2012-12-01

    Most studies to date of biospheric sensitivity to global change have focused on understanding the sensitivity of modern species and communities to recent or experimental environmental change. However, it is unclear how to scale these results towards predicting the response of the biosphere to ongoing global change given that i) similar species often respond individualistically the same perturbation, ii) biotic response often scales nonlinearly with the size and/or duration of environmental change, and iii) many terrestrial and marine community types known from the recent past lack modern analogs. In this context, marine microfossils from deep sea sediments hold enormous promise for furthering our understanding of biotic sensitivity as they capture temporally expanded records of paleoceanographic and biotic response across a range climatic regimes (e.g., icehouse versus greenhouse climates), disturbance types (e.g., from background climate oscillations to mass extinctions), and habitats (e.g., low vs. high latitudes, upwelling vs. gyre ecosystems, etc). Here we use the repeated glacial-interglacial cycles and longer term trend of intensifying Northern Hemisphere glaciation from the Pliocene-Pleistocene to examine issues related to the sensitivity of planktonic foraminiferal species and communities to global change in an icehouse world. More specifically, we quantify the sensitivity and predictability of changes in planktonic foraminiferal species abundance (species specific mass accumulation rates) and community structure (dissimilarity indices and community classification) to glacial-interglacial cycles in the Plio-Pleistocene in two Atlantic sites (ODP Sites 999 and 662). We first examine whether the sensitivity of species and communities to glacial-interglacial cycles in the early Pliocene (~5-3 million years ago) is predictive of i) their sensitivity to the intensification of Northern Hemisphere glaciation (~3-2 million years ago), or ii) their sensitivity to

  19. The secondary history of Sutter's Mill CM carbonaceous chondrite based on water abundance and the structure of its organic matter from two clasts

    NASA Astrophysics Data System (ADS)

    Beck, P.; Quirico, E.; Garenne, A.; Yin, Q.-Z.; Bonal, L.; Schmitt, B.; Montes-Hernandez, G.; Montagnac, G.; Chiriac, R.; Toche, F.

    2014-11-01

    Sutter's Mill is a regolith breccia composed of both heavily altered clasts and more reduced xenoliths. Here, we present a detailed investigation of fragments of SM18 and SM51. We have characterized the water content and the mineralogy by infrared (IR) and thermogravimetric analysis (TGA) and the structure of the organic compounds by Raman spectroscopy, to characterize the secondary history of the clasts, including aqueous alteration and thermal metamorphism. The three methods used in this study suggest that SM18 was significantly heated. The amount of water contained in phyllosilicates derived by TGA is estimated to be approximately 3.2 wt%. This value is quite low compared with other CM chondrites that typically range from 6 to 12 wt%. The infrared transmission spectra of SM18 show that the mineralogy of the sample is dominated by a mixture of phyllosilicate and olivine. SM18 shows an intense peak at 11.2 μm indicative of olivine (Fig. 1). If we compare SM18 with other CM and metamorphosed CM chondrites, it shows one of the most intense olivine signatures, and therefore a lower proportion of phyllosilicate minerals. The Raman results tend to support a short-duration heating hypothesis. In the ID/IG versus FWHM-D diagram, SM18 appears to be unusual compared to most CM samples, and close to the metamorphosed CM chondrites Pecora Escarpment (PCA) 91008 and PCA 02012. In the case of SM51, infrared spectroscopy reveals that olivine is less abundant than in SM18 and the 10 μm silicate feature is more similar to that of moderately altered CM chondrites (like Murchison or Queen Alexandra Range [QUE] 97990). Raman spectroscopy does not clearly point to a heating event for SM51 in the ID/IG versus FWHM-D diagram. However, TGA analysis suggests that SM51 was slightly dehydrated as the amount of water contained in phyllosilicates is approximately 3.7 wt%, which is higher than SM18, but still lower than phyllosilicate water contents in weakly altered CM chondrites

  20. Late-summer zooplankton community structure, abundance, and distribution in the Hudson Bay system (Canada) and their relationships with environmental conditions, 2003-2006

    NASA Astrophysics Data System (ADS)

    Estrada, Rafael; Harvey, Michel; Gosselin, Michel; Starr, Michel; Galbraith, Peter S.; Straneo, Fiammetta

    2012-08-01

    Zooplankton communities were examined for the first time in three different hydrographic regions of the Hudson Bay system (HBS) in early August to early September from 2003 to 2006. Sampling was conducted at 50 stations distributed along different transects located in Hudson Bay (HB), Hudson Strait (HS), and Foxe Basin (FB). Variations in zooplankton biomass, abundance, taxonomic composition, and diversity in relation to environmental variables were studied using multivariate techniques. During all sampling years, the total zooplankton biomass was on average four times lower in HB than in HS and FB. Clustering samples by their relative species compositions revealed no interannual variation in zooplankton community but showed a marked interregional variability between the three regions. Water column stratification explained the greatest proportion (25%) of this spatial variability. According to redundancy analysis (RDA), the zooplankton taxa that contribute most to the separation of the three regions are Microcalanus spp., Oithona similis, Oncaea borealis, Aeginopsis laurentii, Sagitta elegans, Fritillaria sp., and larvae of cnidaria, chaetognatha, and pteropoda in HB; hyperiid amphipods in FB; and Pseudocalanus spp. CI-CV, Calanus glacialis CI-CVI, Calanus finmarchicus CI-CVI, Calanus hyperboreus CV-CVI, Acartia longiremis CI-CV, Metridia longa N3-N6 CI-CIII CVIf, Eukrohnia hamata, larvae of echinodermata, mollusca, cirripedia, appendicularia, and polychaeta in the northwestern and southeastern HS transects. For the HB transect, the RDA analyzed allowed us to distinguish three regions (HB west, central, and east) with different environmental gradients and zooplankton assemblages, in particular higher concentration of Pseudocalanus spp. nauplii and CI-CVI, as well as benthic macrozooplankton and meroplankton larvae in western HB. In HS, Calanoid species (mainly C. finmarchicus and C. glacialis) were mostly observed at the north shore stations associated with the

  1. Age-Based Comparison of Human Dendritic Spine Structure Using Complete Three-Dimensional Reconstructions

    PubMed Central

    Benavides-Piccione, Ruth; Fernaud-Espinosa, Isabel; Robles, Victor; Yuste, Rafael; DeFelipe, Javier

    2013-01-01

    Dendritic spines of pyramidal neurons are targets of most excitatory synapses in the cerebral cortex. Recent evidence suggests that the morphology of the dendritic spine could determine its synaptic strength and learning rules. However, unfortunately, there are scant data available regarding the detailed morphology of these structures for the human cerebral cortex. In the present study, we analyzed over 8900 individual dendritic spines that were completely 3D reconstructed along the length of apical and basal dendrites of layer III pyramidal neurons in the cingulate cortex of 2 male humans (aged 40 and 85 years old), using intracellular injections of Lucifer Yellow in fixed tissue. We assembled a large, quantitative database, which revealed a major reduction in spine densities in the aged case. Specifically, small and short spines of basal dendrites and long spines of apical dendrites were lost, regardless of the distance from the soma. Given the age difference between the cases, our results suggest selective alterations in spines with aging in humans and indicate that the spine volume and length are regulated by different biological mechanisms. PMID:22710613

  2. Impact of hygrothermal aging on structure/function relationship of perfluorosulfonic-acid membrane

    DOE PAGES

    Shi, Shouwen; Dursch, Thomas J.; Blake, Colin; Mukundan, Rangachary; Borup, Rodney L.; Weber, Adam Z.; Kusoglu, Ahmet

    2015-10-20

    Perfluorosulfonic-acid (PFSA) membranes are widely used as the solid electrolyte in electrochemical devices where their main functionalities are ion (proton) conduction and gas separation in a thermomechanically stable matrix. Due to prolonged operational requirements in these devices, PFSA membranes’ properties change with time due to hygrothermal aging. This paper studies the evolution of PFSA structure/property relationship changes during hygrothermal aging, including chemical changes leading to changes in ion-exchange capacity (IEC), nanostructure, water-uptake behavior, conductivity, and mechanical properties. Our findings demonstrate that with hygrothermal aging, the storage modulus increases, while IEC and water content decrease, consistent with the changes in nanostructure,more » that is, water- and crystalline-domain spacings inferred from small- and wide-angle X-ray scattering (SAXS/WAXS) experiments. In addition, the impact of aging is found to depend on the membrane's thermal prehistory and post-treatments, although universal correlations exist between nanostructural changes and water uptake. Lastly, the findings have impact on understanding lifetime, durability, and use of these and related polymers in various technologies.« less

  3. Impact of hygrothermal aging on structure/function relationship of perfluorosulfonic-acid membrane

    SciTech Connect

    Shi, Shouwen; Dursch, Thomas J.; Blake, Colin; Mukundan, Rangachary; Borup, Rodney L.; Weber, Adam Z.; Kusoglu, Ahmet

    2015-10-20

    Perfluorosulfonic-acid (PFSA) membranes are widely used as the solid electrolyte in electrochemical devices where their main functionalities are ion (proton) conduction and gas separation in a thermomechanically stable matrix. Due to prolonged operational requirements in these devices, PFSA membranes’ properties change with time due to hygrothermal aging. This paper studies the evolution of PFSA structure/property relationship changes during hygrothermal aging, including chemical changes leading to changes in ion-exchange capacity (IEC), nanostructure, water-uptake behavior, conductivity, and mechanical properties. Our findings demonstrate that with hygrothermal aging, the storage modulus increases, while IEC and water content decrease, consistent with the changes in nanostructure, that is, water- and crystalline-domain spacings inferred from small- and wide-angle X-ray scattering (SAXS/WAXS) experiments. In addition, the impact of aging is found to depend on the membrane's thermal prehistory and post-treatments, although universal correlations exist between nanostructural changes and water uptake. Lastly, the findings have impact on understanding lifetime, durability, and use of these and related polymers in various technologies.

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

    NASA Astrophysics Data System (ADS)

    Hanafiah, Hazlenah; Jemain, Abdul Aziz

    2013-11-01

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

  5. Macro- and micro-structural white matter differences correlate with cognitive performance in healthy aging.

    PubMed

    Marques, Paulo César Gonçalves; Soares, José Miguel Montenegro; Magalhães, Ricardo José da Silva; Santos, Nadine Correia; Sousa, Nuno Jorge Carvalho

    2016-03-01

    Studies have shown that white matter (WM) volumetric reductions and overall degradation occur with aging. Nonetheless little is known about the WM alterations that may underlie different cognitive status in older individuals. The main goal of the present work was to identify and characterize possible macro and microstructural WM alterations that could distinguish between older healthy individuals with contrasting cognitive profiles (i.e., "poor" vs "good" cognitive performers). Structural and diffusion magnetic resonance imaging was performed in order to quantify local WM volumes, white matter signal abnormalities (WMSA) volume (a measure of lesion burden) and diffusion tensor imaging scalar maps known to probe WM microstructure. A battery of neurocognitive/psychological tests was administered to assess the cognitive performance. Poor performers showed a higher slope for the positive association between WMSA volume and age compared to good performers. Even when controlling for WMSA volume, poor performers also evidenced lower fractional anisotropy, as well as positive associations with age with higher slopes of regression parameters in radial and axial diffusivity. Altogether results suggest that cognitive performance is related to differences in WM, with poor cognitive performers displaying signs of faster aging in WM.

  6. Aging of Iron Nanoparticles in Aqueous Solution: Effects on Structure and Reactivity

    SciTech Connect

    Sarathy, Vaishnavi; Tratnyek, Paul G.; Nurmi, James; Baer, Donald R.; Amonette, James E.; Chun, Chan Lan; Penn, Ryland L.; Reardon, Eric J.

    2008-02-21

    Aging (or longevity) is one of the most important and potentially limiting factors in the use of nano-Fe0 to reduce groundwater contaminants. We investigated the aging of FeH2 (Toda RNIP-10DS) in water with a focus on changes in (i) the composition and structure of the particles (by XPS, XRD, TEM, and bulk Fe0 content), and (ii) the reactivity of the particles (by carbon tetrachloride reaction kinetics and electrochemical corrosion potentials). Our results show that the FeH2 becomes more reactive between 0 and ~2 days aging, and then gradually loses reactivity over the next few hundred days. These changes in reactivity correlate with evidence for rapid destruction of the original Fe(III) oxide film on FeH2 during immersion and the subsequent formation of a new passivating mixed-valence Fe(II)-Fe(III) oxide shell. The behavior of “unaged” nano-Fe0 in the laboratory may be similar to that in field-scale applications for source-zone treatment due to the short reaction times involved. Long-term aged FeH2 acquires properties that are relatively stable over weeks or even months.

  7. The effects of low dose rate irradiation and thermal aging on reactor structural alloys

    NASA Astrophysics Data System (ADS)

    Allen, T. R.; Trybus, C. L.; Cole, J. I.

    As part of the EBR-II reactor materials surveillance program, test samples of fifteen different alloys were placed into EBR-II in 1965. The surveillance (SURV) program was intended to determine property changes in reactor structural materials caused by irradiation and thermal aging. In this work, the effect of low dose rate (approximately 2 × 10 -8 dpa/s) irradiation at 380-410°C and long term thermal aging at 371°C on the properties of 20% cold worked 304 stainless steel, 420 stainless steel, Inconel X750, 304/308 stainless weld material, and 17-4 PH steel are evaluated. Doses of up to 6.8 dpa and thermal aging to 2994 days did not significantly affect the density of these alloys. The strength of 304 SS, X750, 17-4 PH, and 304/308 weld material increased with irradiation. In contrast, the strength of 420 stainless steel decreased with irradiation. Irradiation decreased the impact energy in both Inconel X750 and 17-4 PH steel. Thermal aging decreased the impact energy in 17-4 PH steel and increased the impact energy in Inconel X750. Tensile property comparisons of 304 SURV samples with 304 samples irradiated in EBR-II at a higher dose rate show that the higher dose rate samples had greater increases in strength and greater losses in ductility.

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

    PubMed

    Blanchet, D

    1988-01-01

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

  9. Differences in cognitive aging: typology based on a community structure detection approach

    PubMed Central

    Saliasi, Emi; Geerligs, Linda; Dalenberg, Jelle R.; Lorist, Monicque M.; Maurits, Natasha M.

    2015-01-01

    The current study investigated the extent and patterns of cognitive variability in younger and older adults. An important novelty of this study is the use of graph-based community structure detection analysis to map performance in a mixed population of 79 young and 76 older adults, without separating the age groups a-priori. We identified six subgroups, with distinct patterns of neuropsychological performance. The stability of the identified subgroups was confirmed by employing a cross-validation support vector machine based analysis. The majority of these subgroups comprised either young or older adults, confirming the expected role of aging in cognitive performance. In addition, we identified a subgroup of young and older adults who performed at a similar cognitive level of overall good cognitive performance with slightly decreased processing speed. This result showed that older age is not necessarily associated with general lower cognitive performance and that being young is not necessarily associated with superior cognitive performance. Moreover, cognitively better performing elderly had a significantly higher level of education attainment and higher crystallized intelligence than the other elderly, which suggests that older adults with higher cognitive reserve may be able to cope better with age-related neurobiological change. PMID:25852549

  10. Differences in cognitive aging: typology based on a community structure detection approach.

    PubMed

    Saliasi, Emi; Geerligs, Linda; Dalenberg, Jelle R; Lorist, Monicque M; Maurits, Natasha M

    2015-01-01

    The current study investigated the extent and patterns of cognitive variability in younger and older adults. An important novelty of this study is the use of graph-based community structure detection analysis to map performance in a mixed population of 79 young and 76 older adults, without separating the age groups a-priori. We identified six subgroups, with distinct patterns of neuropsychological performance. The stability of the identified subgroups was confirmed by employing a cross-validation support vector machine based analysis. The majority of these subgroups comprised either young or older adults, confirming the expected role of aging in cognitive performance. In addition, we identified a subgroup of young and older adults who performed at a similar cognitive level of overall good cognitive performance with slightly decreased processing speed. This result showed that older age is not necessarily associated with general lower cognitive performance and that being young is not necessarily associated with superior cognitive performance. Moreover, cognitively better performing elderly had a significantly higher level of education attainment and higher crystallized intelligence than the other elderly, which suggests that older adults with higher cognitive reserve may be able to cope better with age-related neurobiological change.

  11. Structural conformation and leaching from in vitro aged and retrieved Invisalign appliances.

    PubMed

    Schuster, Susan; Eliades, George; Zinelis, Spiros; Eliades, Theodore; Bradley, T Gerard

    2004-12-01

    The objectives of this study were to investigate the structure of Invisalign appliances (Align Technology, Santa Clara, Calif) after intraoral exposure, and to qualitatively and quantitatively characterize the substances leached from the aligners after accelerated in vitro aging. Samples of Invisalign appliances were randomly selected from 10 patients before intraoral placement and after retrieval, and the prepared specimens were subjected to (1) bright-field optical reflection microscopy to study the surface morphology; (2) Fourier transform infrared microspectroscopy to characterize the in vivo changes in molecular composition induced on appliance surfaces, (3) scanning electron microscopy and energy dispersive X-ray microanalysis to identify the elemental composition of integuments formed on the surface, and (4) Vickers hardness (HV 200) testing. Another set of reference and retrieved appliances was subjected to artificial aging for 2 weeks, and the extracts were subjected to gas chromatography-mass spectroscopy. The retrieved appliances demonstrated substantial morphological variation relative to the as-received specimens involving abrasion at the cusp tips, adsorption of integuments, and localized calcification of the precipitated biofilm at stagnation sites. Buccal segments of retrieved appliances showed an increase in hardness, which might be attributed to mastication-induced cold work; however, the clinical implication of this effect on mechanotherapy is unknown. In vitro aged and retrieved appliances were found to leach no traceable amount of substances in an ethanol aging solution.

  12. Normalization of Reverse Transcription Quantitative PCR Data During Ageing in Distinct Cerebral Structures.

    PubMed

    Bruckert, G; Vivien, D; Docagne, F; Roussel, B D

    2016-04-01

    Reverse transcription quantitative-polymerase chain reaction (RT-qPCR) has become a routine method in many laboratories. Normalization of data from experimental conditions is critical for data processing and is usually achieved by the use of a single reference gene. Nevertheless, as pointed by the Minimum Information for Publication of Quantitative Real-Time PCR Experiments (MIQE) guidelines, several reference genes should be used for reliable normalization. Ageing is a physiological process that results in a decline of many expressed genes. Reliable normalization of RT-qPCR data becomes crucial when studying ageing. Here, we propose a RT-qPCR study from four mouse brain regions (cortex, hippocampus, striatum and cerebellum) at different ages (from 8 weeks to 22 months) in which we studied the expression of nine commonly used reference genes. With the use of two different algorithms, we found that all brain structures need at least two genes for a good normalization step. We propose specific pairs of gene for efficient data normalization in the four brain regions studied. These results underline the importance of reliable reference genes for specific brain regions in ageing.

  13. Relationships between brain metabolism decrease in normal aging and changes in structural and functional connectivity.

    PubMed

    Chételat, Gaël; Landeau, Brigitte; Salmon, Eric; Yakushev, Igor; Bahri, Mohamed Ali; Mézenge, Florence; Perrotin, Audrey; Bastin, Christine; Manrique, Alain; Scheurich, Armin; Scheckenberger, Mathias; Desgranges, Béatrice; Eustache, Francis; Fellgiebel, Andreas

    2013-08-01

    Normal aging is characterized by brain glucose metabolism decline predominantly in the prefrontal cortex. The goal of the present study was to assess whether this change was associated with age-related alteration of white matter (WM) structural integrity and/or functional connectivity. FDG-PET data from 40 young and 57 elderly healthy participants from two research centers (n=49/48 in Center 1/2) were analyzed. WM volume from T1-weighted MRI (Center 1), fractional anisotropy from diffusion-tensor imaging (Center 2), and resting-state fMRI data (Center 1) were also obtained. Group comparisons were performed within each imaging modality. Then, positive correlations were assessed, within the elderly, between metabolism in the most affected region and the other neuroimaging modalities. Metabolism decline in the elderly predominated in the left inferior frontal junction (LIFJ). LIFJ hypometabolism was significantly associated with macrostructural and microstructural WM disturbances in long association fronto-temporo-occipital fibers, while no relationship was found with functional connectivity. The findings offer new perspectives to understand normal aging processes and open avenues for future studies to explore causality between age-related metabolism and connectivity changes. PMID:23518010

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

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  15. Can artificial reefs mimic natural reef communities? The roles of structural features and age.

    PubMed

    Perkol-Finkel, S; Shashar, N; Benayahu, Y

    2006-03-01

    In light of the deteriorating state of coral reefs worldwide, the need to rehabilitate marine environments has greatly increased. Artificial reefs (ARs) have been suggested as a tool for reef conservation and rehabilitation. Although successions of AR communities have been thoroughly studied, current understanding of the interactions between artificial and natural reefs (NRs) is poor and a fundamental question still to be answered is that of whether AR communities can mimic adjacent NR communities. We suggest three alternative hypotheses: Neighboring ARs and NRs will (1) achieve a similar community structure given sufficient time; (2) be similar only if they possess similar structural features; (3) always differ, regardless of age or structural features. We examined these hypotheses by comparing the community structure on a 119-year old shipwreck to a neighboring NR. Fouling organisms, including stony and soft corals, sponges, tunicates, sea anemones and hydrozoans were recorded and measured along belt transects. The ahermatypic stony coral Tubastrea micrantha dominated vertical AR regions while the soft corals Nephthea sp. and Xenia sp. dominated both artificial and natural horizontal surfaces. Our results support the second hypothesis, indicating that even after a century an AR will mimic its adjacent NR communities only if it possesses structural features similar to those of the natural surroundings. However, if the two differ structurally, their communities will remain distinct.

  16. Can artificial reefs mimic natural reef communities? The roles of structural features and age.

    PubMed

    Perkol-Finkel, S; Shashar, N; Benayahu, Y

    2006-03-01

    In light of the deteriorating state of coral reefs worldwide, the need to rehabilitate marine environments has greatly increased. Artificial reefs (ARs) have been suggested as a tool for reef conservation and rehabilitation. Although successions of AR communities have been thoroughly studied, current understanding of the interactions between artificial and natural reefs (NRs) is poor and a fundamental question still to be answered is that of whether AR communities can mimic adjacent NR communities. We suggest three alternative hypotheses: Neighboring ARs and NRs will (1) achieve a similar community structure given sufficient time; (2) be similar only if they possess similar structural features; (3) always differ, regardless of age or structural features. We examined these hypotheses by comparing the community structure on a 119-year old shipwreck to a neighboring NR. Fouling organisms, including stony and soft corals, sponges, tunicates, sea anemones and hydrozoans were recorded and measured along belt transects. The ahermatypic stony coral Tubastrea micrantha dominated vertical AR regions while the soft corals Nephthea sp. and Xenia sp. dominated both artificial and natural horizontal surfaces. Our results support the second hypothesis, indicating that even after a century an AR will mimic its adjacent NR communities only if it possesses structural features similar to those of the natural surroundings. However, if the two differ structurally, their communities will remain distinct. PMID:16198411

  17. Age and thermochronology of K-feldspars from the Manson Impact Structure

    NASA Technical Reports Server (NTRS)

    Zeitler, P. K.; Kunk, M. J.

    1993-01-01

    As a contribution to the effort to obtain a precise age for the Manson Impact Structure, we are approaching the problem from a thermo chronological perspective, with the goal of extracting an age from Ar-40/Ar-39 age-spectrum analysis of partially overprinted K-feldspars taken from granitoid clasts. We find that shocked feldspars from Manson generally show a strong overprint in their age spectra, with more than 50 percent of each spectrum being reset. The reset portions of the age spectra correspond to gas lost from very small diffusion domains, and a characteristic of the Manson samples is the very large range in apparent diffusion dimensions that they display, with the smallest domains being some 400 times smaller than the largest domains. It is also noteworthy that the small domains comprise a substantial portion of the volume of the feldspars (50 percent or more). These observations are consistent with the extreme shock experienced by these samples. In detail, the spectra we have measured to date are saddle-shaped and show minimum ages of between 67 and 72 Ma, which we interpret to be maximum estimates for the age of the impact. In the case of one sample (M1-678.3; K-feldspar from a large syenite block located well below the apparent melt-matrix breccia in the M1 borehole), isotope correlation analysis suggests the presence of a non-atmospheric trapped Ar component (Ar-40/Ar-36 of 660 plus or minus 40), and an age of about 65.3 plus or minus 0.5 Ma (2 sigma). Our interpretation of our results is that the shock of impact greatly reduced the diffusion-domain sizes of our samples, making them susceptible to significant Ar loss during heating associated with impact. It appears that while our feldspars were partially open to Ar loss, they equilibrated with a non-atmospheric Ar component, probably related to impact-related degassing of old basement around the impact site.

  18. Living-floors and structures from the Lower Paleolithic to the Bronze Age in Italy.

    PubMed

    Peretto, Carlo; Biagi, Paolo; Boschian, Giovanni; Broglio, Alberto; De Stefani, Mirco; Fasani, Leone; Fontana, Federica; Grifoni, Renata; Guerreschi, Antonio; Iacopini, Andrea; Minelli, Antonella; Pala, Rosalia; Peresani, Marco; Radis, Giovanna; Ronchitelli, Annamaria; Sarti, Lucia; Hohenstein, Ursula Thun; Tozzi, Carlo

    2004-06-01

    New researches have been performed on the analysis of some Italian dwelling structures dating from the Lower Paleolithic to Bronze Age. Different methods have been applied to each study according to the extensions of the areas explored. The following sites have been analyzed: Isernia La Pineta (Molise), Visogliano (Trieste) - Lower Paleolithic; Grotta del Cavallo (Lecce), Grotta Grande and Riparo del Molare (Salerno) - Middle Paleolithic; Grotta di Fumane (Verona), Riparo Tagliente (Verona), Grotta Continenza (Fucino L'Aquila), San Bartolomeo (Maiella Mountain, Abruzzo) - Upper Paleolithic; Mondeval de Sora (Belluno), Alpe Veglia (Verbania) and Grotta Edera (Aurisina, Trieste) -Mesolithic; Cala Giovanna Piano (Pianosa Island, Livorno), Contraguda (Perfugas, Sassari), Colle Santo Stefano (Fucino, L'Aquila), Catignano (Pescara), Settefonti (L'Aquila) - Neolithic; Castellaro Lagusello (Monzambano, Mantua) - Bronze Age. PMID:15636066

  19. Impact of Ice Ages on the genetic structure of trees and shrubs.

    PubMed Central

    Lascoux, Martin; Palmé, Anna E; Cheddadi, Rachid; Latta, Robert G

    2004-01-01

    Data on the genetic structure of tree and shrub populations on the continental scale have accumulated dramatically over the past decade. However, our ability to make inferences on the impact of the last ice age still depends crucially on the availability of informative palaeoecological data. This is well illustrated by the results from a recent project, during which new pollen fossil maps were established and the variation in chloroplast DNA was studied in 22 European species of trees and shrubs. Species exhibit very different levels of genetic variation between and within populations, and obviously went through very different histories after Ice Ages. However, when palaeoecological data are non-informative, inferences on past history are difficult to draw from entirely genetic data. On the other hand, as illustrated by a study in ponderosa pine, when we can infer the species' history with some certainty, coalescent simulations can be used and new hypotheses can be tested. PMID:15101576

  20. Age differences and structural validity for the Greek version of the Body Cathexis Scale.

    PubMed

    Theodorakis, Y; Doganis, G; Bagiatis, K

    1991-02-01

    To examine age differences and the internal structure of the Greek version of the Body Cathexis Scale, 152 women 18 to 45 yr. of age and participating in physical fitness programs took the scale. High internal consistency was evident: in item analysis rs ranged from .29 to .68, split-half r was .89, and Cronbach alpha .92. Factor analysis yielded six factors: (1) Physical Fitness, (2) Total Appearance, (3) Health and Skills, (4) Face, (5) Ears and Chin, and (6) Extremities. These explained 52.5% of the total variance. The higher body satisfaction was observed on the factors, Health and Skills, Ears and Chin, and Extremities. Multivariate analysis of variance of body satisfaction across factors indicated no differences. PMID:2034776

  1. Stability of ultrafine lamellar structures during aging in two-phase {gamma}-TiAl alloys

    SciTech Connect

    Maziasz, P.J.; Liu, C.T.; Wright, J.L.

    1997-08-01

    Two-phase {gamma}-tail alloys such as PM Ti-47Al-2Cr-2Nb or Ti-47Al- 2Cr-1Nb-Ta hot extruded above the {alpha}-transus temperature have unique refined-colony/ultrafine lamellar structures. These lamellar microstructures consist of very fine laths of the {gamma} and {alpha}{sub 2} phases, with average interlamellar spacings of 100 nm and {alpha}{sub 2}-{alpha}{sub 2} spacings of 200 nm, and are dominated by {gamma}/{alpha}{sub 2} interfaces. This ultrafine lamellar structure remains stable during 900 C heat treatment for 2 h, but becomes unstable after 4 h at 982 C. This structure remains stable in both alloys after aging for >5000 h at 800 C but disappears completely at 1000 C. Continuous coarsening begins with dissolution of fine {alpha}{sub 2} lamellea. The