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Sample records for corbicula fluminea influence

  1. Influence of the invasive Asian clam Corbicula fluminea (Bivalvia: Corbiculidae) on estuarine epibenthic assemblages

    NASA Astrophysics Data System (ADS)

    Ilarri, M. I.; Souza, A. T.; Antunes, C.; Guilhermino, L.; Sousa, R.

    2014-04-01

    One of the most widespread invasive alien species (IAS) in aquatic ecosystems is the Asian clam Corbicula fluminea. Several studies have shown that C. fluminea can cause large-scale changes in macrozoobenthic assemblages; however, very few attempted to investigate the effects of this IAS on mobile epibenthic species, such as fishes and crustaceans. In this context, the influence of C. fluminea on epibenthic species was investigated during one year by comparing the associated epibenthic fauna in three nearby sites of the Minho estuary (NW of the Iberian Peninsula), wherein the abiotic conditions are similar but the density of the Asian clam is highly different. From a total of 13 species, six were significantly influenced by C. fluminea; five responded positively, namely the brown shrimp Crangon crangon, the European eel Anguilla anguilla, the common goby Pomatoschistus microps, the brown trout Salmo trutta fario and the great pipefish Syngnathus acus, whereas the shore crab Carcinus maenas was negatively influenced. However, stomach contents analysis revealed that fish and crustacean species do not feed on C. fluminea, suggesting that this IAS is still not a large component of the diet of higher trophic levels in this estuarine ecosystem. Our results suggest that the structure provided by C. fluminea shells is likely to be one of the main factors responsible for the differences observed. C. fluminea physical structure seems to influence the epibenthic associated fauna, when found in densities higher than 1000 ind./m2, with sedentary small-bodied crustaceans and fishes being mainly attracted by the increasing in habitat complexity and consequent enhancement of heterogeneity and shelter availability.

  2. Distribution of Corbicula fluminea at nuclear facilities

    SciTech Connect

    Counts, C.L. III

    1985-11-01

    A review of the zoogeographic records for the exotic Asian clam, Corbicula fluminea (Muller, 1774), reveals its presence in 27 states where nuclear powered electric generating plants are either operating or under construction. Nineteen plant sites reported infestation of varying severity in facilities, or source water bodies immediately adjacent to the facility, by C. fluminea. Thirteen plant sites are located within the zoogeographic limits of C. fluminea but have a low risk of infestation due to either salt water cooling systems or locations a great distance from known populations. Eighteen plant sites are located wholly outside of the known zoogeographic range of C. fluminea. Thirty plant sites are located in close proximity to known populations of C. fluminea and therefore should maintain surveillance of the source water body and within plant water systems for possible infestations by these bivalves. 27 figs.

  3. Mechanisms of cadmium accumulation (adsorption and absorption) by the freshwater bivalve Corbicula fluminea under hydrodynamic conditions.

    PubMed

    Nan, Geng; Peifang, Wang; Chao, Wang; Jun, Hou; Jin, Qian; Lingzhan, Miao

    2016-05-01

    Many heavy metals in sediments and water have potential adverse effects on aquatic organisms such as Corbicula fluminea (O.F. Müller, 1774), a bivalve species frequently used as a biomonitor for metal pollution. Studies over the past decades examining the heavy metal uptake by C. fluminea, very few has investigated the effect of hydrodynamic conditions on accumulation of heavy metal by C. fluminea. Therefore, in this study, to investigate the mechanism of intracellular and extracellular accumulation of metal, individuals of C. fluminea were exposed to cadmium (Cd)-treated water under three different hydrodynamic conditions. These included exposures in two set ups: three rates of rotation (500, 350, 200 r/min) in beakers for 10 days, and then exposure to Cd-treated sediment under two naturally turbulent water conditions (14 cm/s and 3.2 cm/s) in experimental flumes for 23 days. Hydrodynamic force increased the burrowing rate but decreased the activity of C. fluminea. After 10 days of exposure, the extracellular concentrations of Cd in the tissues of C. fluminea in the sand group were significantly higher than that in the gravel groups. The intracellular and extracellular concentrations of Cd in the tissues of C. fluminea dramatically increased in the Cd-treated sediment test. Moreover, the concentration of the extracellular Cd adsorbed on the tissues of C. fluminea in the 14 cm/s and 3.2 cm/s groups was significantly higher than that in the control group, whereas the effect of hydrodynamic force on absorption of Cd by C. fluminea was not obvious. These results suggest that hydrodynamic condition plays an important role in extracellular accumulation of Cd by C. fluminea. In future study, when using C. fluminea to assess Cd pollution in aquatic environment, extracellular Cd adsorbed on the tissue should be removed to avoid the influence of hydrodynamics. Copyright © 2016. Published by Elsevier Ltd.

  4. Comparison of selenium bioaccumulation in the clams Corbicula fluminea and Potamocorbula amurensis: A bioenergetic modeling approach

    USGS Publications Warehouse

    Lee, B.-G.; Lee, J.-S.; Luoma, S.N.

    2006-01-01

    Selenium uptake from food (assimilation efficiency) and dissolved phase (influx rate) as well as loss kinetics (efflux rate) were compared between two bivalves, Corbicula fluminea and Potamocorbula amurensis. The effects of salinity and temperature on these kinetic parameters for both clam species also were evaluated. The Asiatic clam, C. fluminea, more efficiently assimilated Se associated with algae (66-87%) than Se associated with oxic sediments (20-37%). However, no consistent difference was found between Se assimilation efficiencies from both food types (19-60%) for P. amurensis. The temperature and salinity had a minor influence on the Se assimilation from ingested food. However, the effects of temperature and salinity were more evident in the uptake from dissolved sources. The influx rate of Se(IV) increased by threefold with the increase of temperature from 5 to 21??C for C. fluminea. The increase of salinity from 4 to 20 psu decreased the uptake rate constant (ku) of Se in P. amurensis from 0.011 to 0.005 L/g/h, whereas salinity change (0-8 psu) had a negligible effect on the Se influx rate of C. fluminea. The Se influx rate of P. amurensis decreased by half with the 3.5-fold increase in tissue dry weight. The rate constant of loss was greater for P. amurensis (0.029/d at 8 psu) than for C. fluminea (0.014/d at 0 psu and 0.01/d at 8 psu). A bioenergetic model suggests that dietary uptake is the dominant pathway for Se bioaccumulation in the two clams in San Francisco Bay and that interspecies differences in Se bioaccumulation can be explained by differences in food ingestion rates. ?? 2006 SETAC.

  5. When gourmet is not enough: Organic matter sources supporting the production of Corbicula fluminea in an invaded estuary

    EPA Science Inventory

    The Asian clam Corbicula fluminea is one of the most pervasive species in freshwater ecosystems. Our objective was to characterize the food sources fuelling C. fluminea in the Minho river estuary (NW-Iberian Peninsula, Europe), an estuarine ecosystem in which C. fluminea presentl...

  6. When gourmet is not enough: Organic matter sources supporting the production of Corbicula fluminea in an invaded estuary

    EPA Science Inventory

    The Asian clam Corbicula fluminea is one of the most pervasive species in freshwater ecosystems. Our objective was to characterize the food sources fuelling C. fluminea in the Minho river estuary (NW-Iberian Peninsula, Europe), an estuarine ecosystem in which C. fluminea presentl...

  7. Effects of Upper-Limit Water Temperatures on the Dispersal of the Asian Clam Corbicula fluminea

    PubMed Central

    Rosa, Inês Correia; Pereira, Joana Luísa; Costa, Raquel; Gonçalves, Fernando; Prezant, Robert

    2012-01-01

    Temperature is a determinant environmental variable in metabolic rates of organisms ultimately influencing important physiological and behavioural features. Stressful conditions such as increasing temperature, particularly within high ranges occurring in the summer, have been suggested to induce flotation behaviour in Corbicula fluminea which may be important in dispersal of this invasive species. However, there has been no experimental evidence supporting this hypothesis. It was already proven that C. fluminea drift is supported by a mucilaginous drogue line produced by mucocytes present in the ctenidia. Detailed microscopic examination of changes in these cells and quantification of clam flotation following one, two and three weeks of exposure to 22, 25 and 30°C was carried out so that the effects of increasing water temperatures in dispersal patterns could be discussed. Results show that changes in temperature triggered an acceleration of the mucocytes production and stimulated flotation behaviour, especially following one week of exposure. Dilution of these effects occurred following longer exposure periods. It is possible that these bivalves perceive changing temperature as a stress and respond accordingly in the short-term, and then acclimate to the new environmental conditions. The response patterns suggest that increasing water temperatures could stimulate C. fluminea population expansion. PMID:23056377

  8. Purification and characterization of hemagglutinating proteins from Poker-chip Venus (Meretrix lusoria) and Corbicula clam (Corbicula fluminea).

    PubMed

    Cheng, Chin-Fu; Hung, Shao-Wen; Chang, Yung-Chung; Chen, Ming-Hui; Chang, Chen-Hsuan; Tsou, Li-Tse; Tu, Ching-Yu; Lin, Yu-Hsing; Liu, Pan-Chen; Lin, Shiun-Long; Wang, Way-Shyan

    2012-01-01

    Hemagglutinating proteins (HAPs) were purified from Poker-chip Venus (Meretrix lusoria) and Corbicula clam (Corbicula fluminea) using gel-filtration chromatography on a Sephacryl S-300 column. The molecular weights of the HAPs obtained from Poker-chip Venus and Corbicula clam were 358 kDa and 380 kDa, respectively. Purified HAP from Poker-chip Venus yielded two subunits with molecular weights of 26 kDa and 29 kDa. However, only one HAP subunit was purified from Corbicula clam, and its molecular weight was 32 kDa. The two Poker-chip Venus HAPs possessed hemagglutinating ability (HAA) for erythrocytes of some vertebrate animal species, especially tilapia. Moreover, HAA of the HAP purified from Poker-chip Venus was higher than that of the HAP of Corbicula clam. Furthermore, Poker-chip Venus HAPs possessed better HAA at a pH higher than 7.0. When the temperature was at 4°C-10°C or the salinity was less than 0.5‰, the two Poker-chip Venus HAPs possessed better HAA compared with that of Corbicula clam.

  9. Purification and Characterization of Hemagglutinating Proteins from Poker-Chip Venus (Meretrix lusoria) and Corbicula Clam (Corbicula fluminea)

    PubMed Central

    Cheng, Chin-Fu; Hung, Shao-Wen; Chang, Yung-Chung; Chen, Ming-Hui; Chang, Chen-Hsuan; Tsou, Li-Tse; Tu, Ching-Yu; Lin, Yu-Hsing; Liu, Pan-Chen; Lin, Shiun-Long; Wang, Way-Shyan

    2012-01-01

    Hemagglutinating proteins (HAPs) were purified from Poker-chip Venus (Meretrix lusoria) and Corbicula clam (Corbicula fluminea) using gel-filtration chromatography on a Sephacryl S-300 column. The molecular weights of the HAPs obtained from Poker-chip Venus and Corbicula clam were 358 kDa and 380 kDa, respectively. Purified HAP from Poker-chip Venus yielded two subunits with molecular weights of 26 kDa and 29 kDa. However, only one HAP subunit was purified from Corbicula clam, and its molecular weight was 32 kDa. The two Poker-chip Venus HAPs possessed hemagglutinating ability (HAA) for erythrocytes of some vertebrate animal species, especially tilapia. Moreover, HAA of the HAP purified from Poker-chip Venus was higher than that of the HAP of Corbicula clam. Furthermore, Poker-chip Venus HAPs possessed better HAA at a pH higher than 7.0. When the temperature was at 4°C–10°C or the salinity was less than 0.5‰, the two Poker-chip Venus HAPs possessed better HAA compared with that of Corbicula clam. PMID:22666167

  10. Stable oxygen and carbon isotope profiles in an invasive bivalve ( Corbicula fluminea) in North Carolina watersheds

    NASA Astrophysics Data System (ADS)

    Bucci, John P.; Showers, William J.; Genna, Bernie; Levine, Jay F.

    2009-06-01

    The modern invasive bivalve Corbicula fluminea was collected in 2006 from three sites with different land uses located in a North Carolina River Basin. The primary objective was to describe the δ 18O and δ 13C profiles of C. fluminea shells under various land use conditions. An additional aim was to evaluate whether growth patterns of C. fluminea form seasonally. Annual shell growth patterns were measured from the umbo to the margin and co-varied with estimates of ambient water temperature, corresponding to seasonal variation. The C. fluminea growth patterns as translucent bands (slower growth) appeared to form during winter months and opaque bands (rapid growth) formed during summer. A mixed model analysis (ANOVA) showed a significant site level effect of δ 18O and δ 13C profiles examined among sites ( F = 17.1; p = 0.003). A second model showed a borderline significant site effect among profiles with variability more pronounced at the urban site, Crabtree Creek ( p = 0.085). Previous habitat assessment ratings and water chemistry measurements suggested that the urban site was more impacted by storm water runoff. Understanding δ 18O and δ 13C SHELL profiles and shell growth patterns of the invasive bivalve ( C. fluminea) may help establish a framework for using these animals as biomonitors to record water temperature and nutrient pollution.

  11. The role of calcium concentration in the invasive capacity of Corbicula fluminea in crystalline basins.

    PubMed

    Ferreira-Rodríguez, Noé; Fernández, Ignacio; Varandas, Simone; Cortes, Rui; Cancela, M Leonor; Pardo, Isabel

    2017-02-15

    The natural variation of environmental factors in freshwater basins determines their biodiversity. Among them, calcium is a key physiological compound for freshwater invertebrates. It is required for shell formation, muscle contraction, it mediates gene expression and allows counteracting acidosis during stress periods, among other functions. Although the distribution of different freshwater species has been suggested to be linked with the environmental calcium concentration, as yet, no research studies have confirmed this. Identifying whether environmental calcium concentrations might determine the invasion success of alien species would be critical in developing and implementing effective management strategies to control them. Here, a multidisciplinary approach integrating field surveys, analytical chemistry techniques, molecular biology analyses and a lab-scale experiment was taken to decipher whether the environmental calcium concentration might hamper the establishment of Corbicula fluminea in northwestern Iberian rivers. A Principal Component Analysis on water chemistry variables from 13 water bodies identified environmental calcium concentration, among others, as one key factor that best characterized the distribution area of C. fluminea. The calcium content in animals' bodies from two representative rivers was dependent on the environmental calcium concentration of freshwater basins; the lower the concentration, the lower the body's content. The expression of stress- and calcium homeostasis-related genes was higher in C. fluminea from low calcium concentration environments than in those from calcium-rich freshwater basins. Finally, under experimental conditions, lower water calcium concentrations decreased C. fluminea growth rates. The present data suggest, for the first time, that environmental calcium concentration may act as a determinant factor on the invasion success of C. fluminea in freshwater environments. Our results provide new clues for the

  12. Veligers of the invasive Asian clam Corbicula fluminea in the Columbia River Basin: Broadscale distribution, abundance, and ecological associations

    USGS Publications Warehouse

    Hassett, Whitney; Bollens, Stephen M.; Counihan, Timothy D.; Rollwagen-Bollens, Gretchen; Zimmerman, Julie; Emerson, Joshua E.

    2017-01-01

    The invasive Asian clam Corbicula fluminea was introduced to North America in the 1930s and now inhabits most regions of the conterminous United States; however, the distribution and ecology of C. fluminea in the Columbia River Basin is poorly understood. During 2013 and 2014, 5 Columbia-Snake River reservoirs were sampled monthly from May through September, along with 23 additional lakes and reservoirs sampled once each summer. Associations among C. fluminea veligers, other components of the plankton, and environmental variables were analyzed using non-metric multidimensional scaling and canonical correspondence analysis. Corbicula fluminea veligers were found in high abundances in all mainstem Columbia-Snake River reservoirs, with an annual mean abundance of 71.2 individuals per cubic meter (inds./m3). Only 3 of 23 lakes and (non-mainstem) reservoirs contained C. fluminea, with abundances considerably lower (maximum = 21.2 inds./m3) than in the mainstem reservoirs. A diatom-dominated community preceded the spawning of C. fluminea in early summer at all sites. Corbicula fluminea veligers characterized the plankton community in late summer and were associated with cyanobacteria and high water temperatures. A third community, characterized by cyanobacteria, was apparent in non-mainstem sites in July and August. Our analyses describe the relationship of C. fluminea to the plankton community and environment, which contributes to our understanding of the possible effects of C. fluminea infestations and which waterbodies in the Columbia River Basin are at risk for infestation. Understanding the effects and environmental determinants of invasive mollusks will be increasingly important in the future with the possible arrival of zebra (Dreissena polymorpha) or quagga (D. bugensis) mussels to the region.

  13. The asiatic clam, Corbicula fluminea (Müller), in the tidal Potomac River, Maryland

    USGS Publications Warehouse

    Dresler, Paul V.; Cory, Robert L.

    1980-01-01

    The Asiatic clam,Corbicula fluminea (Müller), has extended its range to include the tidal fresh-water portion of the Potomac River, Maryland. Though patchily distributed, the clams have attained densities of 665 m−2. Size-class distributions indicate that the clams first appeared in 1975. About 90% of the population belong to year-class I and were less than 12 mm in length. Elsewhere, this species has created severe water quality problems; it should be closely watched in the Potomac.

  14. Distribution and winter survival health of Asian clams, Corbicula fluminea, in the St. Clair River, Michigan

    USGS Publications Warehouse

    French, John R. P.; Schloesser, Don W.

    1996-01-01

    We studied the distribution and winter survival of the Asian clam, Corbicula fluminea, in the St. Clair River from the fall of 1988 to the spring of 1990. Between fall of 1988 and spring of 1989, distribution of Corbicula was extended from 5.5 to 11.5 km downstream from an electric power plant. However, total abundance of clams decreased during the winter. By fall of 1989, Corbicula was found 14.5 km from the power plant, and the mean density of clams was 27 individuals/m2. Between fall of 1989 and spring of 1990, distribution was reduced to 7.5 km from the power plant and abundance decreased 97%. During the winter of 1988-1989, we collected clams monthly from one station 2.2 km from the power plant, and we observed that clams survived the harsh winter for two months after the water temperature dropped about 1.5°C below the reported lethal level for Corbicula in midwinter. During the winer of 1989-1990, we held clams at the sediment-water interface in enclosures, and we observed that condition indices (dry body weight; dry shell weight) of clams remained stable (mean = 0.05 ± 0.01) in December and January and then declined significantly (p < 0.05) to 0.04 ± 0.01 in February. All clams perished by late March. The deteriorating physiological state of clams, as indicated by declining condition index, seemingly is a factor in late winter mortalities of Corbicula in the St. Clair River. In contrast to the rapid geographic spread and population increases in the southern United States, Corbicula likely will not spread rapidly throughout the Great Lakes beyond shoreline thermal refugia of heated-water discharge plumes from power plants.

  15. Allochthonous Organic Matter Subsidize the High Secondary Production of the Invasive Bivalve Corbicula fluminea in Minho Estuary (N-Portugal)

    EPA Science Inventory

    The Asian clam Corbicula fluminea is one of the most invasive species in freshwater ecosystems. In Minho estuary, this species colonize all the middle and upper part of the estuary, dominating the abundance, biomass and secondary production in River Minho tidal freshwater area (T...

  16. Allochthonous Organic Matter Subsidize the High Secondary Production of the Invasive Bivalve Corbicula fluminea in Minho Estuary (N-Portugal)

    EPA Science Inventory

    The Asian clam Corbicula fluminea is one of the most invasive species in freshwater ecosystems. In Minho estuary, this species colonize all the middle and upper part of the estuary, dominating the abundance, biomass and secondary production in River Minho tidal freshwater area (T...

  17. Accumulation and Growth Responses in Corbicula fluminea Along a Longitudinal Gradient of Metal Exposure

    NASA Astrophysics Data System (ADS)

    Peltier, G. L.; Wright, M. S.; Hopkins, W. A.; Meyer, J. L.

    2005-05-01

    In a previous study, we investigated the concentrations of arsenic, selenium, cadmium, and mercury associated with different land uses in a large river system using an indicator species Corbicula fluminea (Asiatic clam). We found that Corbicula fluminea collected from sites downstream of discharges from coal-fired power plants (CFPP) had significantly higher tissue concentrations of selenium and cadmium than all other land use types. In order to quantify the bioavailability of metals associated with CFPP discharges in a lotic system, we designed a three month experiment in which clams were deployed in cages at four sites along a 3.5 km reach of stream at the Savannah River Site. We assessed metal accumulation in the clam tissue and shell growth over the entire reach. After 84 days, clams at the upstream, most contaminated site had the highest growth rate and highest mean concentrations of arsenic (7.85 ppm), selenium (17.05 ppm), and cadmium (7.28 ppm). Tissue concentrations decreased rapidly over the first 400 m rather than gradually along the entire reach.

  18. Valve movement response of the freshwater clam Corbicula fluminea following exposure to waterborne arsenic.

    PubMed

    Liao, Chung-Min; Jau, Sheng-Feng; Lin, Chieh-Ming; Jou, Li-John; Liu, Chen-Wuing; Liao, Vivian Hsiu-Chuan; Chang, Fi-John

    2009-07-01

    We developed an inductance-based valvometry technique as a detection system to measure the valve daily activity in freshwater clam Corbicula fluminea in response to waterborne arsenic. Our findings reveal that C. fluminea experiences a valve opening in the absence of arsenic predominantly in the morning hours (03:00-08:00) with a mean daily opening/closing period of 21.32 (95% CI: 20.58-22.05) h. Amplification of daily activity occurred in the presence of arsenic. Behavioral toxicity assays revealed arsenic detection thresholds of 0.60 (95% CI: 0.53-0.66) mg l(-1) and 0.35 (95% CI: 0.30-0.40) mg l(-1) for response times of 60 and 300 min, respectively. The proposed valve daily activity model was linked with response time-specific Hill dose-response functions to predict valve opening/closing behavior in response to arsenic. The predictive capabilities were verified satisfactory with the measurements. Our results implicate a biomonitoring system by valve daily activity in C. fluminea to identify safe water uses in areas with elevated arsenic.

  19. Low Genetic Diversity and High Invasion Success of Corbicula fluminea (Bivalvia, Corbiculidae) (Müller, 1774) in Portugal

    PubMed Central

    Gomes, Cidália; Sousa, Ronaldo; Mendes, Tito; Borges, Rui; Vilares, Pedro; Vasconcelos, Vitor; Guilhermino, Lúcia; Antunes, Agostinho

    2016-01-01

    The Asian clam, Corbicula fluminea, is an invasive alien species (IAS) originally from Asia that has spread worldwide causing major ecological and economic impacts in aquatic ecosystems. Here, we evaluated C. fluminea genetic (using COI mtDNA, CYTb mtDNA and 18S rDNA gene markers), morphometric and sperm morphology variation in Portuguese freshwater ecosystems. The COI marker revealed a single haplotype, which belongs to the Asian FW5 invasive lineage, suggesting a common origin for all the 13 Portuguese C. fluminea populations analysed. Morphometric analyses showed differences between the populations colonizing the North (with the exception of the Lima River) and the Centre/South ecosystems. The sperm morphology examination revealed the presence of biflagellate sperm, a distinctive character of the invasive androgenetic lineages. The low genetic variability of the Portuguese C. fluminea populations and the pattern of sperm morphology have been illuminating for understanding the demographic history of this invasive species. We hypothesize that these populations were derived from a unique introductory event of a Corbicula fluminea FW5 invasive androgenic lineage in the Tejo River, which subsequently dispersed to other Portuguese freshwater ecosystems. The C. fluminea asexual reproductive mode may have assisted these populations to become highly invasive despite the low genetic diversity. PMID:27391333

  20. Growth and overwinter survival of the Asiatic clam, Corbicula fluminea, in the St. Clair River, Michigan

    USGS Publications Warehouse

    French, John R. P.; Schloesser, Donald W.

    1991-01-01

    We report the discovery in April 1986 of the first population of Asiatic clam, Corbicula fluminea, known to occupy a lotic environment in the Laurentian Great Lakes system. This population occupied a 3.8 km long sandy shoal in the discharge plume of a steam-electric power plant on the St. Clair River (Michigan), the outflow of Lake Huron. Samples collected April 1986 to April 1987 revealed the growth of one-year-old Corbicula (1985 cohort) began after mid-May and ended by mid-November, while water temperatures were higher than 9°C. Maximum growth (0.78 mm wk-1) occurred between mid-August and mid-September, while water temperatures were about 16-23°C. We recorded a substantial overwinter mortality of the 1986 cohort, but not the 1985 cohort; this was particularly evident at sampling locations more remote from the heated discharge of the power plant, suggesting low water temperature wast the major mortality agent. The available information suggests low water temperature in the St. Clair River may limit the success of Corbicula in the river, including portions of populations inhabiting thermal plumes, by reducing growth, delaying the onset of sexual maturity and reproduction, and causing heavy overwinter mortality in the first year of life.

  1. The unusual mineral vaterite in shells of the freshwater bivalve Corbicula fluminea from the UK

    NASA Astrophysics Data System (ADS)

    Spann, Nicole; Harper, Elizabeth M.; Aldridge, David C.

    2010-08-01

    Asian clams ( Corbicula fluminea) with abnormally thickened shell valves were found in four rivers in the UK (Rivers Yare, Waveney, Thames and New Bedford River). The material making up these malformations was the rare calcium carbonate polymorph vaterite. Vaterite is seldom found in the natural environment because it is less stable than the other calcium carbonate polymorphs (aragonite and calcite). In the few reported cases of vaterite formation in molluscs, it is usually related to unusual biomineralisation events such as shell regeneration, pearls and initial stages of shell formation. We compared two populations from the Rivers Yare and Waveney in the Norfolk Broads, UK, one (River Waveney) displaying dominantly the normal Corbicula shell form with aragonitic shells. In the River Yare population, all individuals sampled had shell deformations to different extents. These deformations were apparent as bulges on the inside of the ventral shell margin. X-ray diffraction confirmed that the shell material in the bulges of recently collected clams was vaterite. Other parts of the deformed shells were aragonitic. The shell deformations alter the shell morphology, leading to higher and wider shells. The shell microstructure is fibrous in the vateritic parts and crossed-lamellar in the aragonitic parts of deformed or non-deformed shells. The cause for the malformations is probably a disrupted biomineralisation process in the bivalves. Fossil Corbicula specimens from the late Pleistocene had similar deformations, suggesting that this is not a response to anthropogenic causes, such as pollution.

  2. Dynamic behaviour of Cd2+ adsorption in equilibrium batch studies by CaCO3(-)-rich Corbicula fluminea shell.

    PubMed

    Ismail, Farhah Amalya; Aris, Ahmad Zaharin; Latif, Puziah Abdul

    2014-01-01

    This work presents the structural and adsorption properties of the CaCO3(-)-rich Corbicula fluminea shell as a natural and economic adsorbent to remove Cd ions from aqueous solutions under batch studies. Experiments were conducted with different contact times, various initial concentrations, initial solution pH and serial biosorbent dosage to examine the dynamic characterization of the adsorption and its influence on Cd uptake capacity. The characterization of the C. fluminea shell using SEM/EDX revealed that the adsorbent surface is mostly impregnated by small particles of potentially calcium salts. The dominant Cd adsorption mechanism is strongly pH and concentration dependent. A maximum Cd removal efficiency of 96.20% was obtained at pH 7 while the optimum adsorbent dosage was observed as 5 g/L. The Langmuir isotherm was discovered to be more suitable to represent the experimental equilibrium isotherm results with higher correlation coefficients (R(2) > 0.98) than Freundlich (R(2) < 0.97).The correlation coefficient values (p < 0.01) indicated the superiority of the Langmuir isotherm over the Freundlich isotherm.

  3. NA{sup +}, K{sup +}-ATPase, histopathological, and genetic responses of Corbicula fluminea to sediment-associated copper

    SciTech Connect

    Brown, S.

    1995-12-31

    Time-dependent responses to sediment-associated copper were studies at hierarchical levels of biological organization along an extreme concentration gradient (40 to 40,000 mg/kg total Cu). Laboratory and in situ estimates of molecular to tissue-level responses (Na/K-ATPase activity, DNA content, histopathology) were monitored in Corbicula fluminea (Asiatic clam), and compared with laboratory and field based survival of Corbicula and Elimia teres (an indigenous Gastropoda). Mollusc survival was, in turn, compared with effects on macrobenthic community composition along the stream/[Cu] gradient. Relationships between selected sediment characteristics and the bioavailability and toxicity of sediment associated copper were also investigated. Sediment-associated copper depressed Na/K-ATPase activity and led to histopathological damage of renal and gill epithelia (vacuolization, degeneration), indicating that impaired ion regulation was an important mechanism of toxicity. Concurrent reductions in DNA content were believed to be secondary effects due to cell death, not an indication of genotoxicity. Sublethal responses were significantly correlated with survival in both species; however, while survival in situ was indicative of differences in community structure, laboratory-based survival was not. Copper levels in tissues were indicative of exposure, but were not significantly correlated with adverse effects. Copper levels in sediments, interstitial water, and overlying water varied independently of sediment characteristics except pH. Cu/AVS ratios were predictive of Corbicula and Elimia survival, but were not significantly related to differences in community structure. Instead, macrobenthic community structure was influenced by other sediment factors (grain size, Eh, pH).

  4. Internal distribution of uranium and associated genotoxic damages in the chronically exposed bivalve Corbicula fluminea.

    PubMed

    Simon, Olivier; Floriani, Magali; Cavalie, Isabelle; Camilleri, Virginie; Adam, Christelle; Gilbin, Rodolphe; Garnier-Laplace, Jacqueline

    2011-08-01

    Uranium (U) internal distribution and involved effects in the bivalve Corbicula fluminea have been studied after direct chronic exposure (90 d, 10 μg.L-1). U distribution was assessed at the subcellular level (Metal Rich Granules -MRG-, pellets and cytosol fractions) in two main organs of the bivalve (gills and visceral mass). Micro-localisation was investigated by TEM-EDX analysis in the gills epithelium. DNA damage in gill and hemolymph samples was measured by the Comet assay. The 90-d exposure period led to a significant increase of U concentration in gills over time (× 5) and a large U quantity in subcellular granules in gills. Finally, a significant increase (× 2) in DNA damage was noted in exposed gills and haemocytes. This study shows that the accumulation levels and consequently the potential toxicity cannot be successfully predicted only on the basis of concentration in water or in tissues and subcellular fractions after chronic exposure.

  5. Multiple Biomarker Responses in Corbicula fluminea Exposed to Copper in Laboratory Toxicity Tests.

    PubMed

    Bonnail, Estefanía; Buruaem, Lucas M; Araujo, Giuliana S; Abessa, Denis M S; DelValls, T Ángel

    2016-08-01

    This study evaluated the alteration of the enzymatic system of the freshwater Asian clam exposed to different copper concentrations. Individuals of Corbicula fluminea were exposed to different concentrations of dissolved Cu (0.5, 1, and 2 mg L(-1)) for 7 days, then, biomarkers of oxidative stress (GST, GPx, GR), exposure (MTs), effect (AChE), and damage (LPO, DNA strand breaks) were quantified. Results showed positive correlations between dissolved metal concentrations and GPx, MTs, and DNA damage, and negative correlation with GST and AChE. In contrast, no clear trend was found for GR and LPO. In general, the established mechanisms of protection might have a beneficial effect on the decreasing ROS attack on membrane and the activation of the metallothioneins. Integrated biomarker analysis revealed that the measured alterations are well correlated with the levels of increasing dissolved copper concentrations in water, demonstrating the effectiveness of this organism for biomonitoring approach purposes.

  6. Comparative sensitivity of European native (Anodonta anatina) and exotic (Corbicula fluminea) bivalves to mercury

    NASA Astrophysics Data System (ADS)

    Oliveira, Patrícia; Lopes-Lima, Manuel; Machado, Jorge; Guilhermino, Lúcia

    2015-12-01

    Pollution is believed to be an important factor modulating the competition between exotic invasive bivalves and their native competitors. Thus, the objective of the present study was to compare the sensitivity of the European native Anodonta anatina and the exotic invasive species Corbicula fluminea to mercury, a ubiquitous environmental contaminant of high concern. In laboratory acute bioassays, adult organisms of both species were exposed independently to mercury for 96 h (31-500 μg/L). The criteria indicative of toxicity were mortality and biomarkers of oxidative stress and damage, neurotoxicity, and energy production changes. Mercury induced mortality in A. anatina (72 h-LC10 and 72 h-LC50 of 14.0 μg/L and 49.6 μg/L, respectively) but not in C. fluminea. The ability of C. fluminea to maintaining the shell closed for considerable periods of time when exposed to high concentrations of mercury and the effective activation (up to 63 μg/L) of mechanisms against the oxidative stress caused by mercury may have contributed to its relatively low sensitivity. In the range of concentrations tested, mercury had no significant effects on the other parameters analysed in C. fluminea. Overall, the findings of the present study, suggest that in real scenarios of competition between C. fluminea and A. anatina populations, the presence of mercury may modulate the process, acting in favour of the exotic species because it is less sensitive to this environmental contaminant than the native bivalve. The results of the present study highlight the need of further investigation on the effects of mercury on the competition between exotic invasive species and their native competitors, especially the effects potentially induced by long-term exposure to low concentrations of this metal, the mechanisms involved in the tolerance to mercury-induced stress, and the potential post-exposure recovery of both exotic invasive and native bivalves. This knowledge is most important for

  7. Modeling habitat suitability of the invasive clam Corbicula fluminea in a Neotropical shallow lagoon, southern Brazil.

    PubMed

    Silveira, T C L; Gama, A M S; Alves, T P; Fontoura, N F

    2016-04-19

    This study aimed to model the habitat suitability for an invasive clam Corbicula fluminea in a coastal shallow lagoon in the southern Neotropical region (-30.22, -50.55). The lagoon (19km2, maximum deep 2.5m) was sampled with an Ekman dredge in an orthogonal matrix comprising 84 points. At each sampling point, were obtained environmental descriptors as depth, organic matter content (OMC), average granulometry (Avgran), and the percentage of sand (Pcsand). Prediction performance of Generalized Linear Models (GLM), Generalized Additive Models (GAM) and Boosted Regression Tree (BRT) were compared. Also, niche overlapping with other native clam species (Castalia martensi, Neocorbicula limosa and Anodontites trapesialis) was examined. A BRT model with 1400 trees was selected as the best model, with cross-validated correlation of 0.82. The relative contributions of predictors were Pcsand-42.6%, OMC-35.8%, Avgran-10.9% and Depth-10.8%. Were identified that C. fluminea occur mainly in sandy sediments with few organic matter, in shallow areas nor by the shore. The PCA showed a wide niche overlap with the native clam species C. martensi, N. limosa and A. trapesialis.

  8. Laboratory and field evaluation of a biological monitoring system using Corbicula fluminea and Mulinia lateralis

    SciTech Connect

    Waller, W.T.; Allen, H.J.; Schwalm, F.U.; Acevedo, M.F.; Ammann, L.P.; Dickson, K.L.; Kennedy, J.H.; Morgan, E.L.

    1995-12-31

    Laboratory and field experiments have been performed to evaluate a non-invasive biomonitoring system using the Asiatic clam Corbicula fluminea and Mulinia lateralis. C. fluminea was exposed to simulated episodic toxicity events in the laboratory using copper, diazinon, and regulated flow rates. Group behavior during these simulated events was compared to behavior during unstressed periods to develop a statistical model and an alarm criteria. Bayou Chico, Pensacola Bay, FL, was the site for field experiments in which M. lateralis was placed in situ to evaluate the performance of the biomonitoring system. The biomonitoring system consists of proximity sensors which detect an aluminum foil target attached to the valve of an organism. Valve movements of the clams are then digitally recorded using a personal computer. Data collected from remote sites are telemetered to the lab using short wave radio. In its final form, the authors envision an in situ biological monitoring system using bivalves deployed in aquatic systems in conjunction with automated monitoring systems like those found at USGS gauging stations. A tool such as this could be used as a warning system to increase the probability of detecting toxic events as they occur.

  9. The Control of an Invasive Bivalve, Corbicula fluminea, Using Gas Impermeable Benthic Barriers in a Large Natural Lake

    NASA Astrophysics Data System (ADS)

    Wittmann, Marion E.; Chandra, Sudeep; Reuter, John E.; Schladow, S. Geoffrey; Allen, Brant C.; Webb, Katie J.

    2012-06-01

    Anoxia can restrict species establishment in aquatic systems and the artificial promotion of these conditions can provide an effective control strategy for invasive molluscs. Low abundances (2-20 m-2) of the nonnative bivalve, Asian clam ( Corbicula fluminea), were first recorded in Lake Tahoe, CA-NV in 2002 and by 2010 nuisance-level population densities (>10,000 m-2) were observed. A non-chemical control method using gas impermeable benthic barriers to reduce dissolved oxygen (DO) concentrations available to C. fluminea was tested in this ultra-oligotrophic natural lake. In 2009, the impact of ethylene propylene diene monomer (EPDM) sheets (9 m2, n = 6) on C. fluminea beds was tested on 1-7 day intervals over a 56 day period (August-September). At an average water temperature of 18 °C, DO concentrations under these small barriers were reduced to zero after 72 h resulting in 100 % C. fluminea mortality after 28 days. In 2010, a large EPDM barrier (1,950 m2) was applied to C. fluminea populations for 120 days (July-November). C. fluminea abundances were reduced over 98 % after barrier removal, and remained significantly reduced (>90 %) 1 year later. Non-target benthic macroinvertebrate abundances were also reduced, with variable taxon-specific recolonization rates. High C. fluminea abundance under anoxic conditions increased the release of ammonium and soluble reactive phosphorus from the sediment substrate; but levels of unionized ammonia were low at 0.004-0.005 mg L-1. Prolonged exposure to anoxia using benthic barriers can provide an effective short term control strategy for C. fluminea.

  10. The control of an invasive bivalve, Corbicula fluminea, using gas impermeable benthic barriers in a large natural lake.

    PubMed

    Wittmann, Marion E; Chandra, Sudeep; Reuter, John E; Schladow, S Geoffrey; Allen, Brant C; Webb, Katie J

    2012-06-01

    Anoxia can restrict species establishment in aquatic systems and the artificial promotion of these conditions can provide an effective control strategy for invasive molluscs. Low abundances (2-20 m(-2)) of the nonnative bivalve, Asian clam (Corbicula fluminea), were first recorded in Lake Tahoe, CA-NV in 2002 and by 2010 nuisance-level population densities (>10,000 m(-2)) were observed. A non-chemical control method using gas impermeable benthic barriers to reduce dissolved oxygen (DO) concentrations available to C. fluminea was tested in this ultra-oligotrophic natural lake. In 2009, the impact of ethylene propylene diene monomer (EPDM) sheets (9 m(2), n = 6) on C. fluminea beds was tested on 1-7 day intervals over a 56 day period (August-September). At an average water temperature of 18 °C, DO concentrations under these small barriers were reduced to zero after 72 h resulting in 100 % C. fluminea mortality after 28 days. In 2010, a large EPDM barrier (1,950 m(2)) was applied to C. fluminea populations for 120 days (July-November). C. fluminea abundances were reduced over 98 % after barrier removal, and remained significantly reduced (>90 %) 1 year later. Non-target benthic macroinvertebrate abundances were also reduced, with variable taxon-specific recolonization rates. High C. fluminea abundance under anoxic conditions increased the release of ammonium and soluble reactive phosphorus from the sediment substrate; but levels of unionized ammonia were low at 0.004-0.005 mg L(-1). Prolonged exposure to anoxia using benthic barriers can provide an effective short term control strategy for C. fluminea.

  11. Assessment of domestic landfill leachate toxicity to the Asian clam Corbicula fluminea via biomarkers.

    PubMed

    Oliveira, Luciana F; Silva, Sandra M C P; Martinez, Claudia B R

    2014-05-01

    In order to evaluate the effects of domestic landfill leachate to bivalves Corbicula fluminea, clams were exposed to different leachate concentrations (v/v): 2, 3, 6 and 10 percent, corresponding to dilutions observed along a stream that receives this effluent, or only to clean water for comparisons. After 5 and 15 days of exposure the activity of the biotransformation enzymes 7-ethoxyresorufin-O-deethylase (EROD) and glutathione S-transferase (GST), the multixenobiotic resistance mechanism (MXR) and lipid peroxidation (LPO) in gills and digestive gland and metallothionein (MT) content in gills were evaluated. Differences in biomarkers responses were observed between gills and digestive gland, except for MXR that decreased in both tissues of clams exposed to 6 percent for 5 days. EROD activity in gills was reduced in all leachate concentrations after 5 days and only in 2 percent after 15 days exposure, while an EROD increase was observed in digestive gland after 15 days exposure to 6 percent. GST activity increased only in the gills of clams exposed to 10 percent for 5 days. LPO varied between tissues and different conditions. A significant increase in LPO was observed in the gills, after 5 days exposure to 2 and 6 percent, and in digestive gland after 5 and 15 days exposure to 2 and 3 percent. MT content in the gills increased after 15 days exposure to 2 percent. In conclusion, different leachate concentrations tested here caused biochemical changes in C. fluminea, but due to the observed variability in biomarkers responses among leachate concentrations, it was difficult to determine patterns or thresholds concentrations.

  12. Nanostructure and crystallography of aberrant columnar vaterite in Corbicula fluminea (Mollusca).

    PubMed

    Frenzel, Max; Harrison, Richard J; Harper, Elizabeth M

    2012-04-01

    Both the crystallographic and nanostructural organisation of aberrant columnar vaterite occurring in Corbicula fluminea were characterised in detail for the first time using electron microscopic and X-ray powder diffraction techniques. At the millimetre scale, only a confinement of the otherwise randomly oriented c-axis to the growth surface is observed. Domains of 100 or more individual vaterite columns with common c-axis orientation exist within this disordered material. Each column behaves as a single crystal on the scale of EBSD measurements, but is internally composed of smaller irregularly shaped and slightly misaligned crystalline units (0.3-1.3μm in dimension). These are in turn partitioned by porous boundaries into rounded nanodomains, up to 600nm in size. The geometry of the nanodomains and their respective boundaries might suggest formation by the accretion of vesicles. In addition to crystallographic textures, this observation indicates formation under significant biological control with wider implications for possible causes of the condition.

  13. Evaluating sublethal indicators of stress in Asiatic clams (Corbicula fluminea) caged in an urban stream

    SciTech Connect

    Black, M.C.; Belin, J.I.

    1998-12-31

    Freshwater bivalves have been used extensively to monitor chemical accumulation in field exposures, although little information is available on the use of biomarker measurements in field exposures with bivalves. DNA strand breakage, growth rate, condition index and percentage tissue water were measured in freshwater Asiatic clams (Corbicula fluminea) exposed in-situ in a stream that receives urban and industrial stormwater runoff and in a non-impacted reference stream. After 4 weeks exposure, DNA strand lengths in foot tissue from Trail Creek-exposed clams were significantly shorter than DNA from reference clams. These results suggest a reduction in DNA integrity in Trail Creek-exposed clams, possibly indicating exposure to genotoxic chemicals. No significant differences were observed in the growth rates of clams. However, a significant inverse relationship was detected between condition index and % tissue water for all clams. Furthermore, site-specific differences in percentage tissue water and condition indices were observed after 2 and 10 weeks exposure. For this study DNA strand breakage, condition indices, and tissue hydration appear to be more sensitive indicators of sublethal toxicity than growth.

  14. Uptake of contaminants of emerging concern by the bivalves Anodonta californiensis and Corbicula fluminea.

    PubMed

    Ismail, Niveen S; Müller, Claudia E; Morgan, Rachel R; Luthy, Richard G

    2014-08-19

    Uptake of seven contaminants regularly detected in surface waters and spanning a range of hydrophobicities (log D(ow) -1 to 5) was studied for two species of freshwater bivalves, the native mussel Anodonta californiensis and the invasive clam Corbicula fluminea. Batch systems were utilized to determine compound partitioning, and flow-through systems, comparable to environmental conditions in effluent dominated surface waters, were used to determine uptake and depuration kinetics. Uptake of compounds was independent of bivalve type. Log bioconcentration factor (BCF) values were correlated with log D(ow) for nonionized compounds with the highest BCF value obtained for triclocarban (TCC). TCC concentrations were reduced in the water column due to bivalve activity. Anionic compounds with low D(ow) values, i.e., clofibric acid and ibuprofen, were not removed from water, while the organic cation propranolol showed biouptake similar to that of TCC. Batch experiments supported compound uptake patterns observed in flow-through experiments. Contaminant removal from water was observed through accumulation in tissue or settling as excreted pseudofeces or feces. The outcomes of this study indicate the potential utility of bivalve augmentation to improve water quality by removing hydrophobic trace organic compounds found in natural systems.

  15. Filter-feeding, food utilization, and nutrient remineralization by Corbicula fluminea (bivalvia) and its contribution to nutrient cycling in a North Carolina River

    SciTech Connect

    Lauritsen, D.D.

    1985-01-01

    The introduced Asiatic clam Corbicula fluminea is quite prolific, and since it is a filter-feeder, it can be expected to influence the cycling of nutrients within its habitat as a result of its feeding and excretory activities. Factors affecting filtration rates, food utilization, and excretion of metabolic wastes (ammonia and phosphate) were determined by laboratory experiments, and these physiological processes were then extrapolated to field estimates of Corbicula found in the upper Chowan River, N.C., to obtain an estimate of the potential impact the clams can have on nutrient cycling in the river. Clam filtration rates of four different /sup 14/C-labeled algae species (two greens, a blue-green, and a diatom) were similar, although partitioning of the ingested isotope showed significant differences between the algal foods. The diatom species was the most efficiently utilized by the clams, with more than 80% of the isotope ingested recovered in clam tissues. Corbicula freshly collected from the Chowan River excreted substantially more ammonia than phosphate, and rates of excretion of both nutrients were highest in summer. Clam excretion rates were much higher than sediment fluxes, and as a source of recycled nutrients, these clams could provide about one third of the nitrogen and phosphate requirements of the phytoplankton in the upper Chowan.

  16. Population density, biomass, and age-class structure of the invasive clam Corbicula fluminea in rivers of the lower San Joaquin River watershed, California

    USGS Publications Warehouse

    Brown, L.R.; Thompson, J.K.; Higgins, K.; Lucas, L.V.

    2007-01-01

    Corbicula fluminea is well known as an invasive filter-feeding freshwater bivalve with a variety of effects on ecosystem processes. However. C. fluminea has been relatively unstudied in the rivers of the western United States. In June 2003, we sampled C. fluminea at 16 sites in the San Joaquin River watershed of California, which was invaded by C. fluminea in the 1940s. Corbicula fluminea was common in 2 tributaries to the San Joaquin River, reaching densities of 200 clams??m-2, but was rare in the San Joaquin River. Biomass followed a similar pattern. Clams of the same age were shorter in the San Joaquin River than in the tributaries. Distribution of clams was different in the 2 tributaries, but the causes of the difference are unknown. The low density and biomass of clams in the San Joaquin River was likely due to stressful habitat or to water quality, because food was abundant. The success of C. fluminea invasions and subsequent effects on trophic processes likely depends on multiple factors. As C. fluminea continues to expand its range around the world, questions regarding invasion success and effects on ecosystems will become important in a wide array of environmental settings.

  17. Biodynamic modeling of PCB uptake by Macoma balthica and Corbicula fluminea from sediment amended with activated carbon.

    PubMed

    McLeod, Pamela B; Luoma, Samuel N; Luthy, Richard G

    2008-01-15

    Activated carbon amendment was assessed in the laboratory as a remediation strategy for freshwater sediment contaminated with polychlorinated biphenyls (PCBs) from the Grasse River (near Massena, NY). Three end points were evaluated: aqueous equilibrium PCB concentration, uptake into semipermeable membrane devices (SPMDs), and 28-day bioaccumulation in the clam Corbicula fluminea. PCB uptake by water, SPMDs, and clams followed similar trends, with reductions increasing as a function of carbon dose. Average percent reductions in clam tissue PCBs were 67, 86, and 95% for activated carbon doses of 0.7, 1.3, and 2.5% dry wt, respectively. A biodynamic model that incorporates sediment geochemistry and dietary and aqueous uptake routes was found to agree well with observed uptake by C. fluminea in our laboratory test systems. Results from this study were compared to 28-day bioaccumulation experiments involving PCB-contaminated sediment from Hunters Point Naval Shipyard (San Francisco Bay, CA) and the clam Macoma balthica. Due to differences in feeding strategy, M. balthica deposit-feeds whereas C. fluminea filter-feeds, the relative importance of the aqueous uptake route is predicted to be much higher for C. fluminea than for M. balthica. Whereas M. balthica takes up approximately 90% of its body burden through sediment ingestion, C. fluminea only accumulates approximately 45% via this route. In both cases, results strongly suggest that it is the mass transfer of PCBs from native sediment to added carbon particles, not merely reductions in aqueous PCB concentrations, that effectively reduces PCB bioavailability and uptake by sediment-dwelling organisms.

  18. Biodynamic modeling of PCB uptake by Macoma balthica and Corbicula fluminea from sediment amended with activated carbon

    USGS Publications Warehouse

    McLeod, Pamela B.; Luoma, S.N.; Luthy, R.G.

    2008-01-01

    Activated carbon amendment was assessed in the laboratory as a remediation strategy for freshwater sediment contaminated with polychlorinated biphenyls (PCBs) from the Grasse River (near Massena, NY). Three end points were evaluated: aqueous equilibrium PCB concentration, uptake into semipermeable membrane devices (SPMDs), and 28-day bioaccumulation in the clam Corbicula fluminea. PCB uptake by water, SPMDs, and clams followed similar trends, with reductions increasing as a function of carbon dose. Average percent reductions in clam tissue PCBs were 67, 86, and 95% for activated carbon doses of 0.7, 1.3, and 2.5% dry wt, respectively. A biodynamic model that incorporates sediment geochemistry and dietary and aqueous uptake routes was found to agree well with observed uptake by C. fluminea in our laboratory test systems. Results from this study were compared to 28-day bioaccumulation experiments involving PCB-contaminated sediment from Hunters Point Naval Shipyard (San Francisco Bay, CA) and the clam Macoma balthica. Due to differences in feeding strategy, M. balthica deposit-feeds whereas C. fluminea filter-feeds, the relative importance of the aqueous uptake route is predicted to be much higher for C. fluminea than for M. balthica. Whereas M. balthica takes up approximately 90% of its body burden through sediment ingestion, C. fluminea only accumulates approximately 45% via this route. In both cases, results strongly suggest that it is the mass transfer of PCBs from native sediment to added carbon particles, not merely reductions in aqueous PCB concentrations, that effectively reduces PCB bioavailability and uptake by sediment-dwelling organisms. ?? 2008 American Chemical Society.

  19. Corbicula fluminea (Bivalvia: Corbiculidae): a possible second molluscan intermediate host of Echinostoma cinetorchis (Trematoda: Echinostomatidae) in Korea

    PubMed Central

    Jung, Younghun; Park, Yun-Kyu; Hwang, Myung-Gi; Soh, Chin-Thack

    2001-01-01

    More than 1,500 clams of Corbicula fluminea, the most favorable food source of freshwater bivalves in Korea, were collected from 5 localities to examine cercarial and metacercarial infection with Echinostoma cinetorchis. Although 3 clams infected with suspicious E. cinetorchis metacercariae out of 200 specimens collected at Kangjin, Chollanam-do were detected, no cercarial and metacercarial infections with E. cinetorchis were observed in field-collected Corbicula specimens. In the susceptibility experiments with laboratory-reared clams, those infected with miracidia of E. cinetorchis did not release their cercariae up to 60 days after infection. To confirm the identity of second intermediate host of E. cinetorchis experimentally, a total of 30 clams were exposed to the cercariae from Segmentina hemisphaerula that had been infected with miracidia of E. cinetorchis. The clams were susceptible to cercariae of E. cinetorchis with an infection rate of 93.3%. Metacercariae from clams taken more than 7 days after cercarial exposure were fed to rats (S/D strain), and adult worms of E. cinetorchis, characterized by 37-38 collar spines on the head crown, were recovered from the ileocecal regions. This is the first report of C. fluminea as a possible second intermediate host of E. cinetorchis. PMID:11775336

  20. An experimental approach to assess Corbicula fluminea (Müller, 1774) resistance to osmotic stress in estuarine habitats

    NASA Astrophysics Data System (ADS)

    Ferreira-Rodríguez, Noé; Pardo, Isabel

    2016-07-01

    Corbicula fluminea arrived in the Miño Estuary in 1989 and, from there, colonized more than 150 km upstream. Our aim was to test the capacity of C. fluminea to cope with osmotic stress conditions previously to invade new freshwater habitats through estuaries. Based on previously collected information, the experiment aims to study the response of the species to marine osmotic stress, evaluated by survival and behaviour. Experiments determined the resistance by the species to various levels of osmotic stress, and recovery time after exposure to high salinity levels, representative of the temporal and spatial salinity variation existing in the estuary. Under osmotic stress the semi-maximum response was reached after 19 days exposure. The species tolerance range, measured by individual maintained activity, was at salinity ∼20 when exposed to winter temperatures, while when animals were exposed to summer ones its tolerance was reduced to salinity lower than 15. C. fluminea show a large physiological flexibility to cope with salinity variations in estuaries. In summer, the temperature increases the metabolic rate thus making the species more vulnerable to osmotic stress exposure. These findings are relevant to preventing new invasions through ship ballast waters ensuring complete mortality if individuals are retained for >26 days.

  1. Sodium Gill Potential as a Tool to Monitor Valve Closure Behavior in Freshwater Clam Corbicula fluminea in Response to Copper

    PubMed Central

    Liao, Chung-Min; Lin, Chieh-Ming; Jou, Li-John; Chen, Wei-Yu

    2008-01-01

    Valve closure behavior in freshwater clam Corbicula fluminea is a biologically sensitive endpoint. The purpose of this paper was to derive an electrophysiological response model of C. fluminea to assess copper (Cu)–sodium (Na) interactions in gill membrane, whereby valve closure behavior and Cu toxicity could be monitored. The proposed model was based on the integration of Cu bioavailability, Na and Cu internalizations, and electrochemically-based gill potentials. Based on Na active transport under non-equilibrium conditions, predicted gill potential of −8.2 mV agreed reasonably well with published the measured transepithelial potential of −7 mV in C. fluminea. Our proposed framework captured the general features observed in model applications including: (i) 50% inhibitory Cu2+ activities for Na membrane potential (ENa) and uptake rate (JNa) were estimated to be 0.072 and 0.043 μM, respectively, with a stoichiometry of 3Cu2+: 1ENa and 1JNa; (ii) the external Cu2+–dependent internal Na concentration could be parsimoniously estimated, and (iii) the site-specific clam gill potentials could be monitored. Here we provided a new approach to monitor waterborne metal toxicity to reduce the nationwide economic losses due to bans on harvesting of contaminated clam and the potential risks to the health of clams. PMID:27873813

  2. Effects of salinity, temperature and food type on the uptake and elimination rates of cd, cr, and zn in the asiatic clam corbicula fluminea

    NASA Astrophysics Data System (ADS)

    Lee, Jung-Suk; Lee, Byeong-Gweon

    2005-06-01

    Laboratory radiotracer experiments were conducted to determine assimilation efficiencies (AE) from ingested algal food and oxic sediment particles, uptake rates from the dissolved phase, and the efflux rates of Cd, Cr and Zn in the Asiatic clam Corbicula fluminea. Among three elements, AE from both algal and sediment food was greatest for Cd, followed by Zn and Cr. The AEs of tested elements from algal food (Phaeodactylum tricornutum) were consistently higher than those from sediments at a given salinity and temperature. The influence of salinity (0, 4 and 8 psu) and temperature (5, 13 and 21¼) on the metal AEs was not evident for most tested elements, except Cd AEs from sediment. The rate constant of metal uptake from the dissolved phase ( k u was greatest for Cd, followed by Zn and Cr in freshwater media. However, in saline water, the k u of Zn were greater than those of Cd. The influx rate of all tested metals increased with temperature. The efflux rate constant was greatest for Cr (0.02 d-1), followed by Zn (0.010~0.017 d-1) and Cd (0.006 d-1). The efflux rate constant for Zn in clam tissues depurated in 0 psu (0.017 d-1) was faster than that in 8 psu (0.010 d-1). Overall results showed that the variation of salinity and temperature in estuarine systems can considerably influence the metal bioaccumulation potential in the estuarine clam C. fluminea. The relatively high Cd accumulation capacity of C. fluminea characterized by the high AE, high dissolved influx rate and low efflux rate, suggested that this clam species can be used as an efficient biomonitor for the Cd contamination in freshwater and estuarine environments.

  3. A comparison of heavy metal concentrations and health assessment in Asian clams Corbicula fluminea from Florida and North Carolina.

    PubMed

    Lewbart, Gregory A; Christian, Larry S; Harms, Craig A; Van Wettere, Arnaud J

    2010-06-01

    The Asian clam Corbicula fluminea was introduced into the United States in 1938 and has since become established in much of the country. This invasive species can compete with native bivalves and compromise industrial water supply systems and power plants. Numerous studies have examined bivalves as bioindicators. The purpose of this study was to compare the heavy metal concentrations of the hard and soft tissues of specimens from Florida and North Carolina and to assess the clams' health by microscopic examination of their soft tissues. Although the sample size was small, this study suggests that the Asian clams from the watersheds examined are healthy and that they accumulate lower levels of heavy metals than have been reported for clams from other, more polluted aquatic environments.

  4. Acetylcholinesterase activity in Corbicula fluminea Mull., as a biomarker of organophosphate pesticide pollution in Pinacanauan River, Philippines.

    PubMed

    Beltran, Kimberly S; Pocsidio, Glorina N

    2010-06-01

    Organophosphates are known to inhibit the enzyme acetylcholinesterase. In this study, the AChE activity from the total soft tissues of Corbicula fluminea Mull. was used as a biomarker of organophosphate pollution in Pinacanauan River. Clams were collected from two different sites and at different seasons of the year. A colorimetric assay on the total soft tissues of the clams showed a directly proportional relationship between enzyme activity and condition of the riverine system. In vitro experiments on the total soft tissue, adductor muscles, digestive glands, and gills were conducted to assess the degree of localization of AChE as well as the sensitivity and tolerance of the enzymes in these tissues to varying concentrations of malathion. The degree of enzyme localization from highest to lowest is as follows: adductor muscle > gills > digestive gland whereas sensitivity to OP from greatest to least is: gills > adductor muscles > digestive gland.

  5. Long-Term Acclimation to Different Thermal Regimes Affects Molecular Responses to Heat Stress in a Freshwater Clam Corbicula Fluminea

    PubMed Central

    Falfushynska, Halina I.; Phan, Tuan; Sokolova, Inna M.

    2016-01-01

    Global climate change (GCC) can negatively affect freshwater ecosystems. However, the degree to which freshwater populations can acclimate to long-term warming and the underlying molecular mechanisms are not yet fully understood. We used the cooling water discharge (CWD) area of a power plant as a model for long-term warming. Survival and molecular stress responses (expression of molecular chaperones, antioxidants, bioenergetic and protein synthesis biomarkers) to experimental warming (20–41 °C, +1.5 °C per day) were assessed in invasive clams Corbicula fluminea from two pristine populations and a CWD population. CWD clams had considerably higher (by ~8–12 °C) lethal temperature thresholds than clams from the pristine areas. High thermal tolerance of CWD clams was associated with overexpression of heat shock proteins HSP70, HSP90 and HSP60 and activation of protein synthesis at 38 °C. Heat shock response was prioritized over the oxidative stress response resulting in accumulation of oxidative lesions and ubiquitinated proteins during heat stress in CWD clams. Future studies should determine whether the increase in thermal tolerance in CWD clams are due to genetic adaptation and/or phenotypic plasticity. Overall, our findings indicate that C. fluminea has potential to survive and increase its invasive range during warming such as expected during GCC. PMID:27995990

  6. Genetic diversity analysis of Asian clam Corbicula fluminea in the Hongze Lake based on mitochondrial cytochrome b gene.

    PubMed

    Zhu, Chuankun; Li, Jin; Xie, Songguang; Ding, Huaiyu; Pan, Zhengjun; Wang, Hui; Chang, Guoliang

    2017-03-24

    The Asian clam Corbicula fluminea is a small bivalve with high nutritional and medical values. However, natural resources of C. fluminea have declined in many areas of China including the Hongze Lake. In this study, 119 individuals from 10 sites of this lake and 2 outgroups were analyzed using a 456 bp mitochondrial cytochrome b (cytb) gene segment. Totally, 19 polymorphic sites were detected, which defined 16 haplotypes. Polymorphism varied among the 10 populations with those at the water inlet being more polymorphic. Most FST values among these populations were below 0.15 with the overall value of 0.060 (p < .05), meanwhile, the overall gene flow was 7.67, both of which indicated the low level of population differentiation in this lake. Neutrality test and mismatch analyses indicated that population explosion may have occurred in this lake. The results obtained in this study will provide useful information for artificial breeding and resource protection of this species in the Hongze Lake.

  7. Yes, caffeine, ibuprofen, carbamazepine, novobiocin and tamoxifen have an effect on Corbicula fluminea (Müller, 1774).

    PubMed

    Aguirre-Martínez, Gabriela V; DelValls, Angel T; Laura Martín-Díaz, M

    2015-10-01

    Reports indicating the presence of pharmaceutical in fresh water environment in the ngL(-1) to µgL(-1) range are occurring with increasing frequency. It is also a fact that pharmaceuticals may produce adverse effects on aquatic organisms. Nevertheless, there is still a lack of knowledge regarding how these emergent contaminants may affect aquatic biota. The goal of this research was to evaluate the sublethal responses in Corbicula fluminea such as, general stress (lysosomal membrane stability [LMS]), biomarkers of phase I and II (etoxyresorufin O-deethylase [EROD], dibenzylfluorescein dealkylase [DBF], gluthathione-S-transferase [GST]), oxidative stress (gluthathione reductase [GR], gluthathione peroxidase [GPX], lipid peroxidation [LPO]), and biomarkers of effect (DNA damage) after 21 days of exposure to caffeine, ibuprofen, carbamazepine, novobiocin and tamoxifen at 0.1, 1, 5, 10, 15, 50µgL(-1). Environmental concentrations tested in this study caused general stress and produced changes on biomarkers tested. LMS, responses from phase I and II enzymatic activity, oxidative stress, and biomarker of effect represent important ecotoxicological information, and will provide a useful reference for the assessment of selected drugs and the effects which these compounds may have on aquatic invertebrates, using C. fluminea as a bioindicator species. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. Proteomic profiling of cytosolic glutathione transferases from three bivalve species: Corbicula fluminea, Mytilus galloprovincialis and Anodonta cygnea.

    PubMed

    Martins, José Carlos; Campos, Alexandre; Osório, Hugo; da Fonseca, Rute; Vasconcelos, Vítor

    2014-01-27

    Suspension-feeding bivalves are considered efficient toxin vectors with a relative insensitivity to toxicants compared to other aquatic organisms. This fact highlights the potential role of detoxification enzymes, such as glutathione transferases (GSTs), in this bivalve resistance. Nevertheless, the GST system has not been extensively described in these organisms. In the present study, cytosolic GSTs isoforms (cGST) were surveyed in three bivalves with different habitats and life strategies: Corbicula fluminea, Anodonta cygnea and Mytilus galloprovincialis. GSTs were purified by glutathione-agarose affinity chromatography, and the collection of expressed cGST classes of each bivalve were identified using a proteomic approach. All the purified extracts were also characterized kinetically. Results reveal variations in cGST subunits collection (diversity and properties) between the three tested bivalves. Using proteomics, four pi-class and two sigma-class GST subunits were identified in M. galloprovincialis. C. fluminea also yielded four pi-class and one sigma-class GST subunits. For A. cygnea, two mu-class and one pi-class GST subunits were identified, these being the first record of GSTs from these freshwater mussels. The affinity purified extracts also show differences regarding enzymatic behavior among species. The variations found in cGST collection and kinetics might justify diverse selective advantages for each bivalve organism.

  9. Assessment of metal contamination, bioavailability, toxicity and bioaccumulation in extreme metallic environments (Iberian Pyrite Belt) using Corbicula fluminea.

    PubMed

    Bonnail, E; Sarmiento, A M; DelValls, T A; Nieto, J M; Riba, I

    2016-02-15

    The Iberian Pyrite Belt (SW Iberian Peninsula) has intense mining activity. Currently, its fluvial networks receive extremely acid lixiviate residue discharges that are rich in sulphates and metals in solution (acid mine drainage, AMD) from abandoned mines. In the current study, the sediment and water quality were analysed in three different areas of the Odiel River to assess the risk associated with the metal content and its speciation and bioavailability. Furthermore, sediment contact bioassays were performed using the freshwater clam Corbicula fluminea to determine its adequacy as a biomonitoring tool in relation to theoretical risk indexes and regulatory thresholds. Reburial activity and mortality were used as the toxic responses of clams when exposed to contaminated sediment. The results showed coherence between the water and sediment chemical contamination for most of the metals. The reburial activity was correlated with the metal toxicity, but no clam mortality was registered. The bioaccumulation of the studied metals in the clam did not have a significant correlation with the bioavailable fraction of the metal content in the environment, which could be related to a potential different speciation in this singular environment. The bioaccumulation responses were negative for As, Cd and Zn in highly contaminated environments and were characterized as severe, considerable and low potential environmental risks, respectively. The results show that C. fluminea is a good biomonitor of Cu and Pb.

  10. Modelling the risk of mortality of Corbicula fluminea (Müller, 1774) (Bivalvia: Corbiculidae) exposed to different turbidity conditions.

    PubMed

    Avelar, W E P; Neves, F F; Lavrador, M A S

    2014-05-01

    The provision of sediment in rivers, due to erosion processes that occur in the environment, consists of a major source of pollution and alteration of the physicochemical conditions of water resources. In addition, the increase in water turbidity may cause siltation, dramatically impacting aquatic communities. Specifically considering the bivalve Corbicula fluminea (Müller, 1774), the aim of this study was to analyse the effect of exposure to different turbidity conditions of sediments, as a risk factor for the animals. For this purpose, a docking device was designed to ensure water circulation in a closed system and to maintain the desired levels of turbidity. Although C. fluminea can generally tolerate environmental changes in aquatic systems, an intolerance to high turbidity levels was experimentally observed, expressed by the mortality rate of the animals when exposed to conditions above 150 nephelometric turbidity units (NTU). This value was similar to the one recorded at study sites in the rivers Pardo (Serrana-SP-Brazil) and Mogi Guaçu (Porto Ferreira-SP-Brazil) during the rainy season. Using a logistic regression model, the experimental results were analysed and the observed mortality rates indicate that the exposure of the animals to turbidity levels above 150 nephelometric turbidity units (NTU), for periods longer than 120 hours, may be considered a probable cause of mortality for the species.

  11. Long-Term Acclimation to Different Thermal Regimes Affects Molecular Responses to Heat Stress in a Freshwater Clam Corbicula Fluminea.

    PubMed

    Falfushynska, Halina I; Phan, Tuan; Sokolova, Inna M

    2016-12-20

    Global climate change (GCC) can negatively affect freshwater ecosystems. However, the degree to which freshwater populations can acclimate to long-term warming and the underlying molecular mechanisms are not yet fully understood. We used the cooling water discharge (CWD) area of a power plant as a model for long-term warming. Survival and molecular stress responses (expression of molecular chaperones, antioxidants, bioenergetic and protein synthesis biomarkers) to experimental warming (20-41 °C, +1.5 °C per day) were assessed in invasive clams Corbicula fluminea from two pristine populations and a CWD population. CWD clams had considerably higher (by ~8-12 °C) lethal temperature thresholds than clams from the pristine areas. High thermal tolerance of CWD clams was associated with overexpression of heat shock proteins HSP70, HSP90 and HSP60 and activation of protein synthesis at 38 °C. Heat shock response was prioritized over the oxidative stress response resulting in accumulation of oxidative lesions and ubiquitinated proteins during heat stress in CWD clams. Future studies should determine whether the increase in thermal tolerance in CWD clams are due to genetic adaptation and/or phenotypic plasticity. Overall, our findings indicate that C. fluminea has potential to survive and increase its invasive range during warming such as expected during GCC.

  12. Long-Term Acclimation to Different Thermal Regimes Affects Molecular Responses to Heat Stress in a Freshwater Clam Corbicula Fluminea

    NASA Astrophysics Data System (ADS)

    Falfushynska, Halina I.; Phan, Tuan; Sokolova, Inna M.

    2016-12-01

    Global climate change (GCC) can negatively affect freshwater ecosystems. However, the degree to which freshwater populations can acclimate to long-term warming and the underlying molecular mechanisms are not yet fully understood. We used the cooling water discharge (CWD) area of a power plant as a model for long-term warming. Survival and molecular stress responses (expression of molecular chaperones, antioxidants, bioenergetic and protein synthesis biomarkers) to experimental warming (20–41 °C, +1.5 °C per day) were assessed in invasive clams Corbicula fluminea from two pristine populations and a CWD population. CWD clams had considerably higher (by ~8–12 °C) lethal temperature thresholds than clams from the pristine areas. High thermal tolerance of CWD clams was associated with overexpression of heat shock proteins HSP70, HSP90 and HSP60 and activation of protein synthesis at 38 °C. Heat shock response was prioritized over the oxidative stress response resulting in accumulation of oxidative lesions and ubiquitinated proteins during heat stress in CWD clams. Future studies should determine whether the increase in thermal tolerance in CWD clams are due to genetic adaptation and/or phenotypic plasticity. Overall, our findings indicate that C. fluminea has potential to survive and increase its invasive range during warming such as expected during GCC.

  13. Proteomic Profiling of Cytosolic Glutathione Transferases from Three Bivalve Species: Corbicula fluminea, Mytilus galloprovincialis and Anodonta cygnea

    PubMed Central

    Martins, José Carlos; Campos, Alexandre; Osório, Hugo; da Fonseca, Rute; Vasconcelos, Vítor

    2014-01-01

    Suspension-feeding bivalves are considered efficient toxin vectors with a relative insensitivity to toxicants compared to other aquatic organisms. This fact highlights the potential role of detoxification enzymes, such as glutathione transferases (GSTs), in this bivalve resistance. Nevertheless, the GST system has not been extensively described in these organisms. In the present study, cytosolic GSTs isoforms (cGST) were surveyed in three bivalves with different habitats and life strategies: Corbicula fluminea, Anodonta cygnea and Mytilus galloprovincialis. GSTs were purified by glutathione-agarose affinity chromatography, and the collection of expressed cGST classes of each bivalve were identified using a proteomic approach. All the purified extracts were also characterized kinetically. Results reveal variations in cGST subunits collection (diversity and properties) between the three tested bivalves. Using proteomics, four pi-class and two sigma-class GST subunits were identified in M. galloprovincialis. C. fluminea also yielded four pi-class and one sigma-class GST subunits. For A. cygnea, two mu-class and one pi-class GST subunits were identified, these being the first record of GSTs from these freshwater mussels. The affinity purified extracts also show differences regarding enzymatic behavior among species. The variations found in cGST collection and kinetics might justify diverse selective advantages for each bivalve organism. PMID:24473139

  14. Evaluation of short-term exposure to heated water and chlorine for control of the Asiatic clam (Corbicula fluminea)

    SciTech Connect

    Mattice, J.S.; McLean, R.B.; Burch, M.B.

    1982-01-01

    Based on the need for development of efficient procedures for prevention or control of fouling by the Asiatic clam, Corbicula fluminea, the response of these clams to chlorine in combination with rapid increases in water temperature was examined. Small clams were acclimated to 10 and 25/sup 0/C, and large clams were acclimated to 25/sup 0/C. Experiments with each of these acclimation groups consisted of variables of total residual chlorine concentration (0, 5, 7.5, and 10 mg/L) and test temperature (ambient and 3 test temperatures ranging from 35 to 46/sup 0/C). The periods of exposure to increased temperature and chlorine were 40 and 30 min respectively. Clam mortalities were related to water temperature but not to chlorine exposure. At high temperatures at least 50% of the clams remained open through the entire chlorine exposure period. At higher temperatures all of the clams remained open. Even when clams remained open for the entire 30-min chlorine exposure period, all clams were not killed. However, virtually all clams exposed to 41 to 43/sup 0/C water temperatures were killed whether open or closed during the exposure period. Death due to temperature shock is the logical conclusion from these data. Combined application of heated water and chlorine at the concentrations used is not more effective in killing Corbicula than is heated water alone. Current regulations on the concentration of chlorine in power plant effluents indicate that further studies of control of Corbicula using chlorine offer little likelihood for success. (ERB)

  15. Sources and accumulation of trace metals in sediments and the asiatic clam, corbicula fluminea in two South Carolina watersheds. Final report

    SciTech Connect

    Pickett, J.R.

    1992-01-01

    A survey of trace element concentrations in the benthic bivalve, Corbicula fluminea, was conducted on the Santee-Cooper River Basin, S.C. from 1989-1991 as part of a nonpoint source water quality assessment. Trace metal concentrations in clam tissues were examined in relation to temporal and spatial variations in river water and sediment. It was found that C. fluminea was a suitable bio-indicator for monitoring trace metal inputs within the basin. Solute concentrations of Cd, Cu and Zn underwent appreciable accumulation as demonstrated by strong solute vs. tissue correlations and high bioconcentration factors. Conversely, the bioavailability of trace elements to C. fluminea was not necessarily related to sediment concentrations, as correlations were not observed between trace elements in sediment and clam tissue. The differences in the bioavailability of metals observed between the watersheds was likely a function of physicochemical factors affecting the partitioning of metals between the water and sediment compartments.

  16. How the fluctuations of water levels affect populations of invasive bivalve Corbicula fluminea (Müller, 1774) in a Neotropical reservoir?

    PubMed

    Paschoal, L R P; Andrade, D P; Darrigran, G

    2015-01-01

    Corbicula fluminea is an invasive bivalve responsible for several environmental and financial problems around the globe. Despite the invasive potential of this species, it suffers certain restrictions in lentic environments due to natural phenomena that significantly affect its population structure (e.g. water column fluctuation and sunlight exposure). The present study addresses how temporal decline of the water level in a Neotropical reservoir and exposure to sunlight affect the population structure of C. fluminea. Samplings were carried out twice in the reservoir of Furnas Hydroelectric Power Station (HPS) (Minas Gerais, Brazil), in 2011 and 2012. Population density, spatial distribution and mean shell length of C. fluminea were estimated for each year after sampling in 51 quadrats (0.0625m2) placed on three transects at different distances along the reservoir margins (0, 10 and 20 m from a fixed-point). We observed a predominance of C. fluminea in both years, with a simultaneous gradual decrease in density and richness of native species in the sampling area. Significant differences in density of C. fluminea were registered at different distances from the margin, and are related to the temporal variability of physical conditions of the sediment and water in these environments. We also registered a trend toward an increase in the density and aggregation of C. fluminea as we moved away from the margin, due to the greater stability of these areas (>10 m). The mean shell length of C. fluminea showed significant difference between the distinct distances from the margin and during the years, as well as the interaction of these factors (Distances vs.Years). These results were associated with the reproductive and invasive capacity of this species. This study reveals that these temporal events (especially water column fluctuation) may cause alterations in density, spatial distribution and mean shell length of C. fluminea and the composition of the native malacofauna in

  17. Bioavailability of cadmium and biochemical responses on the freshwater bivalve Corbicula fluminea--the role of TiO₂ nanoparticles.

    PubMed

    Vale, Gonçalo; Franco, Cristiana; Diniz, Mário S; dos Santos, Margarida M C; Domingos, Rute F

    2014-11-01

    The increasing and widespread applications of TiO2 engineered nanoparticles (nTiO2) led to the release of these materials into aquatic environments and consequently a change on the assessment of the environmental risk of trace metals. In this work, the role of two commercial nTiO2 with distinct crystalline phases and sizes (nTiO2-P25: 80% anatase+20% rutile, d=20nm; nTiO2-NA: 100% anatase, d=5 nm; 0.1 and 1.0 mg L(-1)) on Cd (112 μg L(-1)) speciation, biouptake and toxicity for the freshwater bivalve Corbicula fluminea was evaluated. The electroanalytical technique 'absence of gradients and Nernstian equilibrium stripping (AGNES)' was used to quantify the free Cd concentrations in the exposure medium in presence of both particles. Despite ca. 30-40% decrease of free Cd in the medium in presence of nTiO2, Cd uptake by C. fluminea was similar in the absence and presence of either of the particles. Superoxide dismutase and glutathione-S-transferase activities remained unchanged for Cd in absence and presence of nTiO2, whereas a significant increase of the catalase activity was obtained at the third day for Cd in presence of both nTiO2. Despite lipid peroxidation data shows that the presence of both nTiO2 seems to exert cells damage, a more quantitative description is not possible with the obtained data. The lack of clear-cut responses by the studied biomarkers, even when only in presence of Cd, do not allow insights into the effect of the presence of nTiO2 on the Cd toxicity to the bivalves. Notwithstanding, morphological changes in the digestive gland were clearly obtained in the presence of Cd, nTiO2 and Cd+nTiO2 indicating an inflammatory response.

  18. In situ accumulation of HBCD, PBDEs, and several alternative flame-retardants in the bivalve (Corbicula fluminea) and gastropod (Elimia proxima).

    PubMed

    La Guardia, Mark J; Hale, Robert C; Harvey, Ellen; Mainor, T Matteson; Ciparis, Serena

    2012-06-05

    Alternative brominated flame-retardants (BFRs), 2-ethylhexyl 2,3,4,5-tetrabromobenzoate (TBB), 2-ethylhexyl 2,3,4,5-tetrabromophthalate (TBPH), 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE) and decabromodiphenyl ethane (DBDPE), are now being detected in the environment. However, contaminant bioavailability is influenced by the organisms' ecology (i.e., route of uptake) and in situ environmental factors. We observed that the filter-feeding bivalve (Corbicula fluminea) and grazing gastropod (Elimia proxima), collected downstream from a textile manufacturing outfall, exhibited TBB, TBPH, and BTBPE concentrations from 152 to 2230 ng g(-1) lipid weight (lw). These species also contained additional BFRs. Maximum levels of total hexabromocyclododecane diastereomers (∑HBCDs) in these species were 363,000 and 151,000 ng g(-1) lw, and those of polybrominated diphenyl ethers (∑PBDEs) were 64,900 and 47,200 ng g(-1) lw, respectively. These concentrations are among the highest reported to date worldwide. While BDE-209 was once thought to be nonbioavailable and resistant to degradation, it was the dominant BFR present and likely debromination products were detected. Contributions of α- and β-HBCD were higher in tissues than sediments, consistent with γ-HBCD bioisomerization. Mollusk bioaccumulation factors were similar between HBCD and PBDEs with 4 to 6 bromines, but factors for TBB, TBPH, and BTBPE were lower. Despite different feeding strategies, the bivalves and gastropods exhibited similar BFR water and sediment accumulation factors.

  19. Micro-structure and chemical composition of vateritic deformities occurring in the bivalve Corbicula fluminea (Müller, 1774).

    PubMed

    Frenzel, Max; Harper, Elizabeth M

    2011-05-01

    Vateritic deformities occurring in the invasive heterodont bivalve Corbicula fluminea from several locations in the UK were characterised in detail for the first time using scanning electron microscopy, X-ray diffraction and different geochemical techniques (electron microprobe, ICP-AES, and mass spectrometry). Large volumes of vaterite are produced abnormally in the animals' shells in the form of yellow-green bulges. These are distinguished from the aragonitic parts of the shell by their characteristic micro-structures, content of organic material, trace elemental composition and carbon stable isotope signatures. The most commonly observed micro-structures include columnar vaterite, lamellar vaterite and different irregular structures occurring in all parts of the shell. There are indications that organic material is present largely as intracrystalline impurities or nano-scale phases and not as envelopes around microstructural units. These micro-structures are novel, nothing equivalent having yet been described for other vateritic systems. Euhedral vaterite crystals also occur occasionally. The vaterite has generally higher Mg/Ca and lower Na/Ca, K/Ca than the aragonite. In addition, δ¹³C is also always lower. Microstructural characteristics would suggest loss of biological control probably due to physiological stress(es) inducing the switch to vaterite production. The vaterite might be stabilised by its higher content of organic material and magnesium.

  20. A novel approach for acid mine drainage pollution biomonitoring using rare earth elements bioaccumulated in the freshwater clam Corbicula fluminea.

    PubMed

    Bonnail, Estefanía; Pérez-López, Rafael; Sarmiento, Aguasanta M; Nieto, José Miguel; DelValls, T Ángel

    2017-09-15

    Lanthanide series have been used as a record of the water-rock interaction and work as a tool for identifying impacts of acid mine drainage (lixiviate residue derived from sulphide oxidation). The application of North-American Shale Composite-normalized rare earth elements patterns to these minority elements allows determining the origin of the contamination. In the current study, geochemical patterns were applied to rare earth elements bioaccumulated in the soft tissue of the freshwater clam Corbicula fluminea after exposure to different acid mine drainage contaminated environments. Results show significant bioaccumulation of rare earth elements in soft tissue of the clam after 14 days of exposure to acid mine drainage contaminated sediment (ΣREE=1.3-8μg/gdw). Furthermore, it was possible to biomonitor different degrees of contamination based on rare earth elements in tissue. The pattern of this type of contamination describes a particular curve characterized by an enrichment in the middle rare earth elements; a homologous pattern (EMREE=0.90) has also been observed when applied NASC normalization in clam tissues. Results of lanthanides found in clams were contrasted with the paucity of toxicity studies, determining risk caused by light rare earth elements in the Odiel River close to the Estuary. The current study purposes the use of clam as an innovative "bio-tool" for the biogeochemical monitoring of pollution inputs that determines the acid mine drainage networks affection. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Early defense responses in the freshwater bivalve Corbicula fluminea exposed to copper and cadmium: Transcriptional and histochemical studies.

    PubMed

    Bigot, Aurélie; Minguez, Laëtitia; Giambérini, Laure; Rodius, François

    2011-11-01

    The aim of the present study was to measure the early effects of copper (10 and 50 μg L(-1)), cadmium (2, 10, and 50 μg L(-1)) and mixtures of these metals in the freshwater bivalve Corbicula fluminea exposed for 12 h in laboratory. Transcription levels of superoxide dismutase (SOD), catalase (CAT), selenium-dependent glutathione peroxidase (Se-GPx), pi-class glutathione S-transferase (pi-GST), metallothionein (MT) in digestive gland and gills, and response of lysosomal system and neutral lipids in digestive gland were determined after the exposure period. Results showed that lysosomal system, neutral lipids content, and mRNA levels were modified, suggesting their early response against oxidative stress and their important role in cell integrity. The integrated biomarker response was calculated and showed that the effects of the combinations of Cu and Cd on the biomarker responses are additive. MT and pi-GST mRNA expression correspond to the largest ranges of response. As efficient biomarkers should have an early warning capacity, SOD, CAT, Se-GPx, pi-GST, MT transcripts levels, lysosomal system, and neutral lipids could be used as biomarkers of metal contamination in the aquatic environment.

  2. Invasive zebra mussels (Driessena polymorpha) and Asian clams (Corbicula fluminea) survive gut passage of migratory fish species: implications for dispersal

    USGS Publications Warehouse

    Gatlin, Michael R.; Shoup, Daniel E.; Long, James M.

    2013-01-01

    The introduction and spread of invasive species is of great concern to natural resource managers in the United States. To effectively control the spread of these species, managers must be aware of the multitude of dispersal methods used by the organisms. We investigated the potential for survival through the gut of a migrating fish (blue catfish, Ictalurus furcatus) as a dispersal mechanism for two invasive bivalves: zebra mussel (Driessena polymorpha) and Asian clam (Corbicula fluminea). Blue catfish (N = 62) were sampled over several months from Sooner Lake, Oklahoma, transported to a laboratory and held in individual tanks for 48 h. All fecal material was collected and inspected for live mussels. Survival was significantly related to water temperature in the lake at the time of collection, with no mussels surviving above 21.1 C°, whereas 12 % of zebra mussels (N = 939) and 39 % of Asian clams (N = 408) consumed in cooler water survived gut passage. This research demonstrates the potential for blue catfish to serve as a dispersal vector for invasive bivalves at low water temperatures.

  3. Accumulation of trace elements and growth responses in Corbicula fluminea downstream of a coal-fired power plant.

    PubMed

    Peltier, Gretchen Loeffler; Wright, Meredith S; Hopkins, William A; Meyer, Judy L

    2009-07-01

    Lentic organisms exposed to coal-fired power plant (CFPP) discharges can have elevated trace element concentrations in their tissues, but this relationship and its potential consequences are unclear for lotic organisms. To explore these patterns in a lotic environment, we transplanted Corbicula fluminea from a reference stream to a stream receiving CFPP discharge. We assessed trace element accumulation and glutathione concentration in clam tissue, shell growth, and condition index at five sites along a contamination gradient. Clams at the most upstream and contaminated site had the highest growth rate, condition index, glutathione concentrations, and concentrations of arsenic (7.85+/-0.25 microg/g [dry mass]), selenium (17.75+/-0.80 microg/g), and cadmium (7.28+/-0.34 microg/g). Mercury concentrations declined from 4.33+/-0.83 to 0.81+/-0.11 microg/g [dry mass] in clams transplanted into the selenium-rich environment nearest the power plant, but this effect was not as evident at less impacted, downstream sites. Even though dilution of trace elements within modest distances from the power plant reduced bioaccumulation potential in clams, long-term loading of trace elements to downstream depositional regions (e.g., slow moving, silty areas) is likely significant.

  4. Accumulation of trace elements and growth responses in Corbicula fluminea downstream of a coal-fired power plant

    SciTech Connect

    Peltier, G.L.; Wright, M.S.; Hopkins, W.A.; Meyer, J.L.

    2009-07-15

    Lentic organisms exposed to coal-fired power plant (CFPP) discharges can have elevated trace element concentrations in their tissues, but this relationship and its potential consequences are unclear for lotic organisms. To explore these patterns in a lotic environment, we transplanted Corbicula fluminea from a reference stream to a stream receiving CFPP discharge. We assessed trace element accumulation and glutathione concentration in clam tissue, shell growth, and condition index at five sites along a contamination gradient. Clams at the most upstream and contaminated site had the highest growth rate, condition index, glutathione concentrations, and concentrations of arsenic (7.85 {+-} 0.25 {mu} g/g (dry mass)), selenium (17.75 {+-} 0.80 {mu} g/g), and cadmium (7.28 {+-} 0.34 {mu} g/g). Mercury concentrations declined from 4.33 {+-} 0.83 to 0.81 {+-} 0.11 {mu} g/g (dry mass) in clams transplanted into the selenium-rich environment nearest the power plant, but this effect was not as evident at less impacted, downstream sites. Even though dilution of trace elements within modest distances from the power plant reduced bioaccumulation potential in clams, long-term loading of trace elements to downstream depositional regions (e.g., slow moving, silty areas) is likely significant.

  5. Responses of cytochrome P450, GST, and MXR in the mollusk Corbicula fluminea to the exposure to hospital wastewater effluents.

    PubMed

    Bonnafé, Elsa; Sroda, Sophie; Budzinski, Hélène; Valière, Amélie; Pedelluc, Julie; Marty, Pierre; Geret, Florence

    2015-07-01

    Pharmaceutical products are a major group of chemical compounds that are continuously released into the environment. The primary pathway of pharmaceuticals to the aquatic environment is the discharge of wastewater effluents. The Psychiatric hospital of Montpon (Dordogne, France) operates with its wastewater treatment plant. We first evaluated the presence and concentrations of 27 pharmaceuticals compounds in these effluents. All of the 27 compounds were detected in these wastewater effluents at concentrations ranging between 37,500 ng L(-1) (paracetamol) and 150 ng L(-1) (citalopram). The aim of the study was then to evaluate the exposure effects of the effluents on cytochrome P450, GST, and MXR responses in Corbicula fluminea gills and digestive glands. Experiments on clams exposed during 1, 3, 7 14, and 21 days revealed a strong and continuous overexpression of mdr1 (multidrug resistant 1) gene expression in gills and transitory variations in pi-gst expression and GST activity. EROD activity increased also transitory after 1 day in the digestive gland of exposed clams. These results indicated that in the effluent, some molecules have undergone metabolism of phase 1 and/or phase 2.

  6. Effects of the human antiepileptic drug carbamazepine on the behavior, biomarkers, and heat shock proteins in the Asian clam Corbicula fluminea.

    PubMed

    Chen, Huihui; Zha, Jinmiao; Liang, Xuefang; Li, Jiasu; Wang, Zijian

    2014-10-01

    Carbamazepine (CBZ), an anticonvulsant and mood-stabilizing pharmaceutical, is a widespread contaminant in aquatic environments. In this study, the effects of chronic exposure to environmentally relevant CBZ concentrations were investigated in freshwater clams Corbicula fluminea. Adult C. fluminea were exposed to 0.5, 5, and 50 μg/L of CBZ for 30 days, after which siphoning behavior (filtration rates), biomarker levels, and heat shock protein expression were measured. The filtration rates were significantly decreased (p<0.05) by 50 μg/L CBZ treatment, indicating a negative impact on C. fluminea health. Superoxide dismutase (SOD) and glutathione reductase (GR) activities were decreased, and catalase (CAT) activity and malondialdehyde (MDA) content were increased in the gills and digestive gland, suggesting that CBZ induced an oxidative effect. The levels of Hsp22, Hsp40, and Hsp70 mRNAs were also markedly induced after 5 or 50 μg/L CBZ treatment (p<0.05), whereas Hsp60 and Hsp90 mRNAs in gills and Hsp60 mRNA in digestive gland were significantly repressed (p<0.05). Finally, the expression of Hsp70 protein was significantly increased (p<0.05) by 5 and 50 μg/L exposure. In aggregate, these results confirm that environmentally relevant concentrations of CBZ can exert a negative effect on C. fluminea tissue at the molecular and protein level.

  7. Effect of fluctuating low-level chlorine concentrations on valve-movement behavior of the asiatic clam (corbicula fluminea)

    SciTech Connect

    Ham, K.D. . Graduate Program in Ecology); Peterson, M.J. )

    1994-03-01

    Asiatic clams (Corbicula fluminea) exposed to water from the upstream section of East Fork Popular Creek (Oak Ridge, TN), a stream receiving chlorine-containing industrial discharges, were monitored for changes in valve movement patterns. Individual clams were attached to an automated valve-movement monitoring apparatus and suspended in flow-through tanks located streamside. Valve-closure behavior of two clams exposed to untreated water was compared to that of two clams exposed to dechlorinated water for two 18-d periods. Chlorine concentrations in untreated water exhibited a pronounced diurnal cycle, fluctuating between a mean daily minimum of 0.02 mg/L total residual chlorine (TRC) during the day and a mean daily maximum of 0.07 mg/L TRC at night during the second monitoring period. In over 2,300 fifteen-minute intervals, clams closed for 0.70 of the intervals while exposed to untreated water, but closed for only 0.22 of the intervals while exposed to dechlorinated water. Treatment differences in valve closure were tested by repeated-measures ANOVA. A significant treatment effect on valve closure was found in the first monitoring period. Graphical analysis of valve-closure records revealed duel cycles that differed between treatments. Clams in untreated water usually opened only near midday, when TRC concentrations were lowest. Clams in dechlorinated water opened more often, for longer periods, and appeared to respond to dawn and dusk changes in light. The valve-closure behavior of clams in untreated water effectively minimized tissue exposure to waterborne TRC, presumably reducing toxic effects. Valve-closure monitoring in conjunction with other studies may help estimate the effect of tissue isolation on the toxicity or bioaccumulation of waterborne chemicals. Such estimates could improve prediction of toxicological or ecological consequences of stressful conditions on bivalves.

  8. Bioaccumulation and metallothionein response in the Asiatic clam (Corbicula fluminea) after experimental exposure to cadmium and inorganic mercury

    SciTech Connect

    Baudrimont, M.; Metivaud, J.; Maury-Brachet, R.; Ribeyre, F.; Boudou, A.

    1997-10-01

    The involvement of metallothioneins (MTs) in cadmium (Cd) and inorganic mercury (Hg[II]) bioaccumulation by the freshwater bivalve Corbicula fluminea was experimentally investigated after 0, 15, 30 and 45 d of exposure from the water column source. Three levels of contamination were studied for each metal: 0, 5, and 35 {micro}g Cd/L and 0, 1.45, and 5 {micro}g Hg/L, with two replicates per condition. Forty eight experimental units (EUs) were conducted simultaneously. The mollusks were fed twice a week by additions of phytoplanktonic algae. Quantification of MTs was done by Hg-saturation assay, using cold Hg(II). A partial purification of these proteins was conducted by gel-filtration chromatography, followed by Cd determinations in the different eluted fractions. Results at the whole organism (soft tissues) and organ or tissue group (gills, mantle, foot, visceral mass) levels show high metal concentrations, with a fourfold greater accumulation of inorganic Hg than Cd after 30 d exposure at the same concentration of 5 {micro}g/L. Gills and visceral mass were the principal storage compartments. A significant increase in MT concentrations was revealed in these two organs after exposure to Cd: ratios between the MT concentrations in contaminated and control mollusks were 2.4 and 2.8, respectively, for 5 and 35 {micro}g Cd/L. Cd burdens in the cytosol and in {le}18-kDa protein fractions, similar to purified mammal MTs, correspond to 30 and 14% of the total Cd accumulated in the whole organisms. No significant increase in MT biosynthesis was observed after exposure to inorganic Hg, despite the high metal concentrations in the organs.

  9. Identification of larvae: The zebra mussel (Dreissena polymorpha), quagga mussel (Dreissena rosteriformis bugensis), and Asian clam (Corbicula fluminea)

    USGS Publications Warehouse

    Nichols, S. Jerrine; Black, M.G.

    1994-01-01

    There are presently four freshwater bivalves in the United States that produce larvae or veligers commonly found in the water column: two forms of Asian clams and two species of dreissenids. Portions of the geographic range of three of these bivalves, one species of Asian clam (Corbicula fluminea), zebra mussels (Dreissena polymorpha), and quagga mussels (Dreissena rosteriformis bugensis), overlap, causing problems with larval identification. To determine which characteristics can be used to separate larval forms, adult Asian clams, quaggas, and zebra mussels were brought into the laboratory and induced to spawn, and the resulting larvae were reared. Hybrids between quaggas and zebra mussels were also produced, but not reared to maturity. Characteristics allowing for the most rapid and accurate separation of larvae were hinge length, shell length/height, shell shape, shell size, and the presence or absence of a foot and velum. These characteristics were observed in laboratory-reared larvae of known parentage and field-caught larvae of unknown parentage. In most cases, larvae of the Asian clam can be readily separated from those produced by either type of dreissenid on the basis of shell size and presence of a foot. Separating the gametes and embryos of the two types of dreissenids is not possible, but after shell formation, most of the larval stages can be distinguished. Hinge length, shell length/height, and the similarity in size of the shell valves can be used to separate straight-hinged, umbonal, pediveliger, and plantigrade larvae. Quagga × zebra mussel hybrids show characteristics of both parents and are difficult to identify.

  10. Integrated biomarker responses of the invasive species Corbicula fluminea in relation to environmental abiotic conditions: a potential indicator of the likelihood of clam's summer mortality syndrome.

    PubMed

    Oliveira, Cristiana; Vilares, Pedro; Guilhermino, Lúcia

    2015-04-01

    The aim of this study was to investigate the variation of several biomarkers in wild populations of Corbicula fluminea in relation to abiotic condition changes to identify environmental factors associated with increased stress in this species potentially leading to massive mortality events. The study was carried out from July to October in the freshwater tidal areas of the estuaries of Minho and Lima Rivers (NW Iberian Peninsula). Monthly, 7 biomarkers (biotransformation, energy production, anti-oxidant defenses and lipid peroxidation damages) were determined in C. fluminea and 17 abiotic parameters were determined in water or sediments in 4 sampling sites: M1, M2 and M3 in Minho (up=> downstream); and L in Lima estuaries. The results of biomarkers were integrated using the Integrated Biomarker Response (IBR), Index and also analysed in relation to environmental parameters by Redundancy Analysis (RDA). Overall, the findings of the present study indicate that July and August are particularly stressful months for the studied C. fluminea populations, especially at downstream sites; the increase of nutrients and ammonium water concentrations, water temperature and conductivity are major contributors for this increased stress; the biomarkers indicated that in July/August C. fluminea is exposed to oxidative stress inducers, environmental chemical contaminants biotransformed by esterases and glutathione S-transferase enzymes, and that organisms need additional energy to cope with the chemical and/or thermally-induced stress. The findings of the present study stress the importance of biomonitoring the health condition of C. fluminea because it may allow determining the likelihood of summer/post summer mortality syndrome in this species.

  11. Population dynamics of Corbicula fluminea (Müller, 1774) in mesohaline and oligohaline habitats: Invasion success in a Southern Europe estuary

    USGS Publications Warehouse

    Franco, J.N.; Ceia, F.R.; Patricio, J.; Thompson, John; Marques, J.C.; Neto, J.M.

    2012-01-01

    Due to its range expansion and potential ecological effects, Corbicula fluminea is considered one of the most important non-indigenous species (NIS) in aquatic ecosystems. Its presence since 2003 in the upstream area of Mondego estuary (oligohaline and mesohaline sectors) was studied during thirteen months, from December 2007 to December 2008. Monthly mean abundance and biomass ranged from 542 to 11142 individuals m-2 and 13.1–20.4 g Ash Free Dry Weight m-2, respectively. Populations of C.fluminea were composed mostly of juveniles, always present in extremely high densities compared to other estuarine ecosystems (e.g. Minho estuary) suggesting a continuous recruitment pattern. The hydraulic regime of the River Mondego favours the downstream colonization of the upper Mondego estuary by recruits produced upstream. However, salinity in these sectors of the estuary apparently neither favours growth nor the establishment of structured populations of this species. Other factors like contaminants and predation, which were not studied, could also contribute to the community structure observed.

  12. Bioavailability and toxicity of metals from a contaminated sediment by acid mine drainage: linking exposure-response relationships of the freshwater bivalve Corbicula fluminea to contaminated sediment.

    PubMed

    Sarmiento, Aguasanta M; Bonnail, Estefanía; Nieto, José Miguel; DelValls, Ángel

    2016-11-01

    Streams and rivers strongly affected by acid mine drainage (AMD) have legal vacuum in terms of assessing the water toxicity, since the use of conventional environmental quality biomarkers is not possible due to the absence of macroinvertebrate organisms. The Asian clam Corbicula fluminea has been widely used as a biomonitor of metal contamination by AMD in freshwater systems. However, these clams are considered an invasive species in Spain and the transplantation in the field study is not allowed by the Environmental Protection Agency. To evaluate the use of the freshwater bivalve C. fluminea as a potential biomonitor for sediments contaminated by AMD, the metal bioavailability and toxicity were investigated in laboratory by exposure of clams to polluted sediments for 14 days. The studied sediments were classified as slightly contaminated with As, Cr, and Ni; moderately contaminated with Co; considerably contaminated with Pb; and heavily contaminated with Cd, Zn, and specially Cu, being reported as very toxic to Microtox. On the fourth day of the exposure, the clams exhibited an increase in concentration of Ga, Ba, Sb, and Bi (more than 100 %), followed by Co, Ni, and Pb (more than 60 %). After the fourth day, a decrease in concentration was observed for almost all metals studied except Ni. An allometric function was used to determine the relationship between the increases in metal concentration in soft tissue and the increasing bioavailable metal concentrations in sediments.

  13. [Effects of eutrophication on distribution and population density of Corbicula fluminea and Bellamya sp. in Chaohu Lake].

    PubMed

    Deng, Daogui; Li, Hongyuan; Hu, Wanming; Zhou, Qiong; Guo, Longgen

    2005-08-01

    The investigation on the distribution an d population density of C. fluminea and Bellamya sp. in Chaohu Lake during September 2001 and September 2002 showed that in the west region of the lake where was seriously eutrophic, the density and biomass of C. fluminea were 5.1 ind. x m(-2) and 17.87 g x m(-2) in 2001, and 8.8 ind. x m(-2) and 47.29 g x m(-2) in 2002, while those of Bellamya sp. were 13.3 ind. x m(-2) and 45.45 g x m(-2) in 2001, and 3.8 ind. x m(-2) and 12.56 g x m(-2) in 2002, respectively. In the east region of the lake where was eutrophic, the density and biomass of C. fluminea were 23.8 ind. x m(-2) and 67.86 g x m(-2) in 2001, and 29.2 ind. x m(-2) and 96.18 g x m(-2) in 2002, while those of Bellamya sp. were 10.1 ind. x m(-2) and 32.00 g x m(-2) in 2001, and 9.4 ind. x m(-2) and 31.21 g x m(-2) in 2002, respectively. The density and biomass of C. fluminea and Bellamya sp. were declined with increasing eutrophication. In hypertrophic region, C. fluminea and Bellamya sp. were absent. The density and biomass of the two species were obviously higher in littoral than in pelagic region. The distribution type of C. fluminea was core-model, while that of Bellamya sp. was random. The correlation between the density and biomass of C. fluminea and Bellamya sp. and water depth was not significant (P > 0.05). The biomass of Bellamya sp. was negatively correlated with water TN (P < 0.01), NO3-N (P < 0.05), TP(P < 0.01) and PO4-P (P < 0.05), while that of C. fluminea only had a significantly negative correlation with PO4-P(P < 0.05). Compared with 1981, there was fewer C. fluminea in the lake nowadays. The effects of other environmental factors on the population distribution and growth of C. fluminea and Bellamya sp. were also discussed.

  14. Protein-Bound Polysaccharide from Corbicula fluminea Inhibits Cell Growth in MCF-7 and MDA-MB-231 Human Breast Cancer Cells

    PubMed Central

    Liao, Ningbo; Zhong, Jianjun; Zhang, Ronghua; Ye, Xingqian; Zhang, Yanjun; Wang, Wenjun; Wang, Yuexia; Chen, Shiguo; Liu, Donghong; Liu, Ruihai

    2016-01-01

    A novel protein-bound polysaccharide, CFPS-1, isolated from Corbicula fluminea, is composed predominantly of mannose (Man) and glucose (Glc) in a molar ratio of 3.1:12.7. The polysaccharide, with an average molecular weight of about 283 kDa, also contains 10.8% protein. Atomic force microscopy, high-performance liquid chromatography, Fourier transform infrared spectroscopy, gas chromatography/mass spectrometry, and nuclear magnetic resonance spectroscopy analyses revealed that CFPS-1 has a backbone of 1,6-linked and 1,4,6-linked-α-D-Glc, which is terminated with a 1-linked-α-D-Man residue at the O-4 position of 1,4,6-linked-α-D-Glc, in a molar ratio of 3:1:1. Preliminary in vitro bioactivity tests revealed that CFPS-1 effectively and dose-dependently inhibits human breast cancer MCF-7 and MDA-MB-231 cell growth, with an IC50 of 243 ± 6.79 and 1142 ± 14.84 μg/mL, respectively. In MCF-7, CFPS-1 produced a significant up-regulation of p53, p21, Bax and cleaved caspase-7 and down-regulation of Cdk4, cyclin D1, Bcl-2 and caspase-7. These effects resulted in cell cycle blockade at the S-phase and apoptosis induction. In contrast, in MDA-MB-231, with limited degree of change in cell cycle distribution, CFPS-1 increases the proportion of cells in apoptotic sub-G1 phase executed by down-regulation of Bcl-2 and caspase-7 and up-regulation of Bax and cleaved caspase-7. This study extends our understanding of the anticancer mechanism of C. fluminea protein-bound polysaccharide. PMID:27959954

  15. The Asian clam Corbicula fluminea as a biomonitor of trace element contamination: Accounting for different sources of variation using an hierarchical linear model

    USGS Publications Warehouse

    Shoults-Wilson, W. A.; Peterson, J.T.; Unrine, J.M.; Rickard, J.; Black, M.C.

    2009-01-01

    In the present study, specimens of the invasive clam, Corbicula fluminea, were collected above and below possible sources of potentially toxic trace elements (As, Cd, Cr, Cu, Hg, Pb, and Zn) in the Altamaha River system (Georgia, USA). Bioaccumulation of these elements was quantified, along with environmental (water and sediment) concentrations. Hierarchical linear models were used to account for variability in tissue concentrations related to environmental (site water chemistry and sediment characteristics) and individual (growth metrics) variables while identifying the strongest relations between these variables and trace element accumulation. The present study found significantly elevated concentrations of Cd, Cu, and Hg downstream of the outfall of kaolin-processing facilities, Zn downstream of a tire cording facility, and Cr downstream of both a nuclear power plant and a paper pulp mill. Models of the present study indicated that variation in trace element accumulation was linked to distance upstream from the estuary, dissolved oxygen, percentage of silt and clay in the sediment, elemental concentrations in sediment, shell length, and bivalve condition index. By explicitly modeling environmental variability, the Hierarchical linear modeling procedure allowed the identification of sites showing increased accumulation of trace elements that may have been caused by human activity. Hierarchical linear modeling is a useful tool for accounting for environmental and individual sources of variation in bioaccumulation studies. ?? 2009 SETAC.

  16. Oxidative stress and histological changes following exposure to diamond nanoparticles in the freshwater Asian clam Corbicula fluminea (Müller, 1774).

    PubMed

    Cid, Antonio; Picado, Ana; Correia, José Brito; Chaves, Rúben; Silva, Héber; Caldeira, Jorge; de Matos, António P Alves; Diniz, Mário S

    2015-03-02

    Recently, the scientific community became aware of the potential ability of nanoparticles to cause toxicity in living organisms. Therefore, many of the implications for aquatic ecosystems and its effects on living organisms are still to be evaluated and fully understood. In this study, the toxicity of nanodiamonds (NDs) was assessed in the freshwater bivalve (Corbicula fluminea) following exposure to different nominal concentrations of NDs (0.01, 0.1, 1, and 10 mg l(-1)) throughout 14 days. The NDs were characterized (gravimetry, pH, zeta potential, electron microscopy, and atomic force microscopy) confirming manufacturer information and showing NDs with a size of 4-6 nm. Oxidative stress enzymes activities (glutathione-S-transferase, catalase) and lipid peroxidation were determined. The results show a trend to increase in GST activities after seven days of exposure in bivalves exposed to NDs concentrations (>0.1 mg l(-1)), while for catalase a significant increase was found in bivalves exposed from 0.01 to 1.0 mg l(-1) following an exposure of 14 days. The histological analysis revealed alterations in digestive gland cells, such as vacuolization and thickening. The lipid peroxidation showed a trend to increase for the different tested NDs concentrations which is compatible with the observed cellular damage.

  17. Field transplantation of the freshwater bivalve Corbicula fluminea along a polymetallic contamination gradient (River Lot, France): 2. Metallothionein response to metal exposure

    SciTech Connect

    Baudrimont, M.; Andres, S.; Metivaud, J.; Lapaquellerie, Y.; Ribeyre, F.; Maillet, N.; Latouche, C.; Boudou, A.

    1999-11-01

    Specimens of the Asiatic clam Corbicula fluminea were transplanted from a clean lacustrine site to four stations along a polymetallic pollution gradient in the river Lot, France, downstream from an old Zn ore treatment facility (see Part 1). From April to September 1996, the authors studied Cd and Zn bioaccumulation and the metallothionein-like metal-binding protein (MT) concentrations by subsampling the ages at t = 0, 21, 49, 85, 120, and 150 d. Marked differences were observed among the four stations. At the most polluted station Riou-Mort, MT concentrations did not increase despite very rapid metal accumulation; all mollusks died between days 49 and 85, suggesting that the metal detoxification mechanisms were overwhelmed at this station. At the next station downstream, the final levels of bioaccumulated metal after 150 d were as high as those at the Riou-Mort station, but in this case the MT concentrations also increased progressively with positive correlations between MT and metal concentrations; no mortality was observed, but a significant growth inhibition was revealed in comparison to the reference site, with a lack of correlation between MT and reduced growth. Subcellular metal partitioning, as determined by size-exclusion chromatography, revealed that most of the Cd was sequestered by MT. In contrast, most of the Zn was bound to low molecular weight proteins, the MT fraction representing only 12% of cytosolic zn. These data show the marked role of MT toward Cd bioaccumulation and toxic effects on this freshwater bivalve species.

  18. The Asian clam Corbicula fluminea as a biomonitor of trace element contamination: accounting for different sources of variation using an hierarchical linear model.

    PubMed

    Shoults-Wilson, W Aaron; Peterson, James T; Unrine, Jason M; Rickard, James; Black, Marsha C

    2009-10-01

    In the present study, specimens of the invasive clam, Corbicula fluminea, were collected above and below possible sources of potentially toxic trace elements (As, Cd, Cr, Cu, Hg, Pb, and Zn) in the Altamaha River system (Georgia, U.S.A.). Bioaccumulation of these elements was quantified, along with environmental (water and sediment) concentrations. Hierarchical linear models were used to account for variability in tissue concentrations related to environmental (site water chemistry and sediment characteristics) and individual (growth metrics) variables while identifying the strongest relations between these variables and trace element accumulation. The present study found significantly elevated concentrations of Cd, Cu, and Hg downstream of the outfall of kaolin-processing facilities, Zn downstream of a tire cording facility, and Cr downstream of both a nuclear power plant and a paper pulp mill. Models of the present study indicated that variation in trace element accumulation was linked to distance upstream from the estuary, dissolved oxygen, percentage of silt and clay in the sediment, elemental concentrations in sediment, shell length, and bivalve condition index. By explicitly modeling environmental variability, the Hierarchical linear modeling procedure allowed the identification of sites showing increased accumulation of trace elements that may have been caused by human activity. Hierarchical linear modeling is a useful tool for accounting for environmental and individual sources of variation in bioaccumulation studies.

  19. Halogen-free organophosphorus flame retardants caused oxidative stress and multixenobiotic resistance in Asian freshwater clams (Corbicula fluminea).

    PubMed

    Yan, Saihong; Wu, Huimin; Qin, Jianhui; Zha, Jinmiao; Wang, Zijian

    2017-03-16

    Halogen-free organophosphorus flame retardants are widespread in aquatic environments. Although it has been documented that they affect the behavior and reproduction of aquatic species, researches investigating cellular detoxification and the defense system in bivalves are scarce. In this study, adult Asian clams (C. fluminea) were exposed to tris (2-butoxyethyl) phosphate (TBEP) and tributyl phosphate (TBP) at 20, 200, and 2000 μg/L for 28 d. The results showed no noticeable difference in siphoning behavior. However, the siphoning behavior displayed a trend toward a slight decrease in the treatment groups. GR activity was markedly reduced compared with the control groups, whereas the levels of cyp4 significantly increased following the 2000 μg/L TBP treatments (p < 0.05). Moreover, the levels of gsts1 and gstm1 significantly decreased following all TBEP treatments and were significantly inhibited by 20 μg/L TBP (p < 0.05). The adverse effects on antioxidant enzymes suggested that C. fluminea mainly relies on the antioxidant system to reduce damage without an increase in MDA levels following exposure to a low concentration. Moreover, mRNA expression levels of heat shock proteins (hsp 22, 40, 60, 70, and 90) were significantly down-regulated with TBEP and TBP treatments lower than 200 μg/L (p < 0.05), whereas significant up-regulations were observed for hsp 22 and hsp 70 in response to 2000 μg/L TBP treatment (p < 0.05). Up-regulation of ATP-binding cassette (ABC) transporter genes (abcb1 and abcc1) showed that TBEP and TBP could activate the multixenobiotic resistance (MXR) system to discharge xenobiotics in C. fluminea, which kept its shell closed at high concentrations to prevent xenobiotic entry. Our results provide a new insight into the different mechanisms of cellular detoxification and the MXR system of C. fluminea in response to low and high concentrations of TBEP and TBP.

  20. Rare earth elements in the aragonitic shell of freshwater mussel Corbicula fluminea and the bioavailability of anthropogenic lanthanum, samarium and gadolinium in river water.

    PubMed

    Merschel, Gila; Bau, Michael

    2015-11-15

    High-technology metals - such as the rare earth elements (REE) - have become emerging contaminants in the hydrosphere, yet little is known about their bioavailability. The Rhine River and the Weser River in Germany are two prime examples of rivers that are subjected to anthropogenic REE input. While both rivers carry significant loads of anthropogenic Gd, originating from contrast agents used for magnetic resonance imaging, the Rhine River also carries large amounts of anthropogenic La and lately Sm which are discharged into the river from an industrial point source. Here, we assess the bioavailability of these anthropogenic microcontaminants in these rivers by analyzing the aragonitic shells of the freshwater bivalve Corbicula fluminea. Concentrations of purely geogenic REE in shells of comparable size cover a wide range of about one order of magnitude between different sampling sites. At a given sampling site, geogenic REE concentrations depend on shell size, i.e. mussel age. Although both rivers show large positive Gd anomalies in their dissolved loads, no anomalous enrichment of Gd relative to the geogenic REE can be observed in any of the analyzed shells. This indicates that the speciations of geogenic and anthropogenic Gd in the river water differ from each other and that the geogenic, but not the anthropogenic Gd is incorporated into the shells. In contrast, all shells sampled at sites downstream of the industrial point source of anthropogenic La and Sm in the Rhine River show positive La and Sm anomalies, revealing that these anthropogenic REE are bioavailable. Only little is known about the effects of long-term exposure to dissolved REE and their general ecotoxicity, but considering that anthropogenic Gd and even La have already been identified in German tap water and that anthropogenic La and Sm are bioavailable, this should be monitored and investigated further. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Water-quality assessment of the Albemarle-Pamlico Drainage Basin, North Carolina and Virginia; organochlorine compounds in Asiatic clam (Corbicula fluminea) soft tissues and whole redbrest sunfish (Lepomis auritus) 1992-93

    USGS Publications Warehouse

    Smith, K.E.; Ruhl, P.M.

    1996-01-01

    The analysis of potential contaminants in biological tissues is an important part of many water-quality assessment programs, including the National Water-Quality Assessment (NAWQA) Program. Tissue analyses often are used to provide information about (1) direct threats to ecosystem integrity, and (2) the occurrence and distribution of potential contaminants in the environment. During 1992-93, Asiatic clam (Corbicula fluminea) soft tissues and whole redbreast sunfish (Lepomis auritus) samples were collected and analyzed to obtain information about the occurrence and distribution of organochlorine compounds in the Albemarle-Pamlico drainage Basin of North Carolina and Virginia. The investigation was conducted as part of the NAWQA Program. Relatively few organochlorine compounds were detected and of the compounds detected, all were detected in relatively low concentrations. The organochlorine compounds detected were p,p'-DDD, p,p'-DDE, p,p'-DDT, dieldrin, trans-nonachlor, PCB's, and toxaphene. Multiple compounds were detected at 16 of 19 sites sampled. Compared to Asiatic clams, redbreast sunfish appear to be better bioindicators of organochlorine contamination in aquatic systems. Except for one detection of toxaphene, pesticide concentrations are well below the National Academy of Sciences and National Academy of Engineering (NAS/NAE) guidelines for the protection of fish-eating wildlife.

  2. Water-quality assessment of the Albemarle-Pamlico drainage basin, North Carolina and Virginia; trace elements in Asiatic clam (Corbicula fluminea) soft tissues and redbreast sunfish (Lepomis auritus) livers, 1992-93

    USGS Publications Warehouse

    Ruhl, P.M.; Smith, K.E.

    1996-01-01

    The analysis of potential contaminants in biological tissues is an important part of many water-quality assessment programs, including the National Water-Quality Assessment (NAWQA) Program. Tissue analyses often are used to provide information about (1) direct threats to ecosystem integrity, and (2) the occurrence and distribution of potential contaminants in the environment. During 1992-93, trace elements in Asiatic clam (Corbicula fluminea) soft tissues and redbreast sunfish (Lepomis auritus) livers were analyzed to obtain information about the occurrence and distribution of trace element contaminants in the Albemarle-Pamlico Drainage Basin of North Carolina and Virginia. The investigation was conducted as part of the NAWQA Program. All but 3 of the 22 trace elements that were analyzed were detected. Although all 10 of the U.S. Environmental Protection Agency (U.S. EPA) priority pollutants were detected in the tissues sampled, they were present in relatively low concentrations. Concentrations of U.S. EPA priority pollutants in Asiatic clams collected in the Albemarle-Pamlico Drainage Basin are similar to concentrations observed in other NAWQA study units in the southeastern United States. Mercury (a U.S. EPA priority pollutant) was widely detected, being present in 29 of 30 tissue samples, but concentrations did not exceed the FDA action level for mercury of a risk-based screening value for the general public. Mercury concentrations in Asiatic clams were similar to concentrations in other NAWQA study areas in the Southeast.

  3. Field transplantation of the freshwater bivalve Corbicula fluminea along a polymetallic contamination gradient (River Lot, France): 1. Geochemical characteristics of the sampling sites and cadmium and zinc bioccumulation kinetics

    SciTech Connect

    Andres, S.; Baudrimont, M.; Lapaquellerie, Y.; Ribeyre, F.; Maillet, N.; Latouche, C.; Boudou, A.

    1999-11-01

    Specimens of the Asiatic clam Corbicula fluminea were transplanted from a clean lacustrine site to four stations along a polymetallic gradient in the river Lot (France), downstream from an old Zn ore treatment facility. The bivalves were held in benthic cages for a 5-month exposure period, April to September 1996; mollusk growth and metal bioaccumulation kinetics (Cd, Zn) were followed by subsampling the cages at t = 0, 21, 49, 85, 120, and 150 d. Rates of Cd bioaccumulation in the whole soft bodies and in individual organs were greater at the upstream stations located close to the pollution source, but there was no direct proportionality between Cd in the bivalves and in the unfiltered or filtered river water samples. Unlike the case for Cd, rates of Zn bioaccumulation did not reflect the contamination gradient. Marked growth differences were measured among the four stations, reflecting both nutritional differences and changes in the degree of metal contamination; these growth differences produced markedly different trends when metal bioaccumulation was expressed in terms of burdens rather than concentrations.

  4. Delineating copper accumulation pathways for the freshwater bivalve Corbicula using stable copper isotopes.

    PubMed

    Croteau, Marie-Noële; Luoma, Samuel N

    2005-11-01

    Delineation of metal uptake routes in aquatic invertebrates is critical for characterizing bioaccumulation dynamics and assessing risks associated with metal exposure. Here we demonstrate that Cu stable isotopic ratios can be manipulated in both exposure media and algae to determine the efflux rate constant (ke) and to estimate Cu assimilation efficiency (AE) from ingested food in a freshwater bivalve (Corbicula fluminea). The Cu AE in Corbicula fed 65Cu-spiked Cryptomonas ozolini was 38%. Copper uptake routes had no significant influence on efflux; ke of 0.004 per day characterized the slowest component of efflux following short-term exposures to 65Cu in water or in both food and water. Incorporation of the physiological parameters for dietary and dissolved uptake as well as rate constants of loss into a bioaccumulation model allowed for assessing the relative contribution of water and food as Cu sources. At [65Cu2+] of 6.7 microg/L, Corbicula accumulated twice as much Cu from diet as from water. In most freshwater systems, the dietary pathway is likely to act as the major Cu uptake route for Corbicula. Extrapolation of our laboratory results to the San Francisco Bay-Delta (California, USA) indicated that our biodynamic model and the laboratory-derived parameters for dietary 65Cu uptake provided a realistic representation of the processes involved in Cu accumulation by the bivalve Corbicula.

  5. Delineating copper accumulation pathways for the freshwater bivalve Corbicula using stable copper isotopes

    USGS Publications Warehouse

    Croteau, M.-N.; Luoma, S.N.

    2005-01-01

    Delineation of metal uptake routes in aquatic invertebrates is critical for characterizing bioaccumulation dynamics and assessing risks associated with metal exposure. Here we demonstrate that Cu stable isotopic ratios can be manipulated in both exposure media and algae to determine the efflux rate constant (ke) and to estimate Cu assimilation efficiency (AE) from ingested food in a freshwater bivalve (Corbicula fluminea). The Cu AE in Corhicula fed 65Cu-spiked Cryptomonas ozolini was 38%. Copper uptake routes had no significant influence on efflux; ke, of 0.004 per day characterized the slowest component of efflux following short-term exposures to 65Cu in water or in both food and water. Incorporation of the physiological parameters for dietary and dissolved uptake as well as rate constants of loss into a bioaccumulation model allowed for assessing the relative contribution of water and food as Cu sources. At [65Cu 2+] of 6.7 ??g/L, Corbicula accumulated twice as much Cu from diet as from water. In most freshwater systems, the dietary pathway is likely to act as the major Cu uptake route for Corbicula. Extrapolation of our laboratory results to the San Francisco Bay-Delta (California, USA) indicated that our biodynamic model and the laboratory-derived parameters for dietary 65Cu uptake provided a realistic representation of the processes involved in Cu accumulation by the bivalve Corbicula. ?? 2005 SETAC.

  6. Engineering factors influencing Corbicula fouling in nuclear-service water systems

    SciTech Connect

    Henager, C.H.; Johnson, K.I.; Page, T.L.

    1983-06-01

    Corbicula fouling is a continuing problem in nuclear-service water systems. More knowledge of biological and engineering factors is needed to develop effective detection and control methods. A data base on Corbicula fouling was compiled from nuclear and non-nuclear power stations and industries using raw water. This data base was used in an analysis to identify systems and components which are conducive to fouling by Corbicula. Bounds on several engineering parameters such as velocity and temperature which support Corbicula growth are given. Service water systems found in BWR and PWR reactors are listed and those that show fouling are identified. Possible safety implications of Corbicula fouling are discussed for specific service water systems. Several effective control methods in current use include backflushing with heated water, centrifugal strainers, and continuous chlorination during spawning seasons.

  7. Mercury accumulation in caged Corbicula: rate of uptake and seasonal variation.

    PubMed

    Neufeld, Douglas S G

    2010-09-01

    The uptake and seasonal fluctuations of total mercury were followed in caged and uncaged Asiatic clams, Corbicula fluminea, over a 1-year period in South River, Virginia. Mercury was rapidly accumulated in clams transplanted from a nominally uncontaminated site into cages on the contaminated South River, reaching 0.99 microg g(-1) dry mass within the first month. Resident clams moved to cages had higher mercury contents after the first month (2.04 microg g(-1) dry mass) and at all subsequent times in the study. Large monthly fluctuations in mercury were noted for both resident caged and transplant caged clams with a notable peak occurring in early spring (4.31 microg g(-1) dry mass in resident caged clams). Tissue mass of caged clams steadily increased through the winter and early spring. Adjustment of mercury concentrations for tissue mass changes indicated that the changes in mercury contents were primarily due to uptake/release rather than changes in tissue mass (concentration/dilution). The present study demonstrates the utility of using caged Corbicula as mercury biomonitors and illustrates the importance of accounting for large, short-term changes of mercury content in Corbicula when designing long-term biomonitoring studies.

  8. Phylogeny and androgenesis in the invasive Corbicula clams (Bivalvia, Corbiculidae) in Western Europe

    PubMed Central

    2011-01-01

    Background The genus Corbicula is one of the most invasive groups of molluscs. It includes both sexual and androgenetic lineages. The present study re-assessed the different morphotypes and haplotypes of West European Corbicula in order to clarify their taxonomic identification and phylogenetic relationships with American and Asian Corbicula clams. We studied several populations from West European river basins (Meuse, Seine, Rhine and Rhône) through an "integrative taxonomy" approach. We combined morphology, partial mitochondrial COI and cyt b sequences and eleven microsatellite loci. Furthermore, we looked for discrepancies between mtDNA and nrDNA/morphology, indicative of androgenesis between lineages. Results There are three Corbicula morphotypes in Western Europe associated to three mitochondrial lineages and three genotypes. Form R shares the same COI haplotype as the American form A and the Japanese C. leana. Form S and the American form C have the same haplotype, although their morphologies seem divergent. The European form Rlc belongs to the same mitochondrial lineage as both the American form B and the Asian C. fluminea. Interestingly, within each haplotype/genotype or lineage, no genetic diversity was found although their invasive success is high. Moreover, we detected rare mismatches between mtDNA and nrDNA/morphology, indicative of androgenesis and mitochondrial capture between form R and form S and therefore challenging the phylogenetic relatedness and the species status within this genus. The global phylogenetic analysis revealed that the sexual Corbicula lineages seem restricted to the native areas while their androgenetic relatives are widespread and highly invasive. Conclusions We clarified the discrepancies and incongruent results found in the literature about the European morphotypes of Corbicula and associated mitochondrial lineages. The three West European morphotypes belong to three distinct nuclear and mitochondrial lineages. However

  9. The influence of fish cage culture on δ13C and δ15N of filter-feeding Bivalvia (Mollusca).

    PubMed

    Benedito, E; Figueroa, L; Takeda, A M; Manetta, G I

    2013-11-01

    The objective of this study was to evaluate the effect of Oreochromis niloticus cage culture promoted variations in the δ13C and δ15N in Corbicula fluminea (Mollusca; Bivalvia) and in the sediment of an aquatic food web. Samples were taken before and after net cage installation in the Rosana Reservoir (Paranapanema River, PR-SP). Samples of specimens of the bivalve filterer C. fluminea and samples of sediment were collected using a modified Petersen grab. All samples were dried in an oven (60 °C) for 72 hours, macerated to obtain homogenous fine powders and sent for carbon (δ13C) and nitrogen (δ15N) isotopic value analysis in a mass spectrometer. There were significant differences in the δ13C and δ15N values of the invertebrate C. fluminea between the beginning and the end of the experiment. There were no differences between the δ13C and δ15N values of sediment. These results indicate that the installation of fish cage culture promoted impacts in the isotopic composition of the aquatic food web organisms, which could exert influence over the native species and the ecosystem.

  10. Corbicula fluminea as a Bioaccumulation Indicator Species: A Case Study at the Columbia and Willamette Rivers

    DTIC Science & Technology

    2009-06-01

    Station 19, which had the highest mercury concentrations ( 171 ng/g). A second subgroup consisting of Stations 1 and 20A had moderate to high levels...method 1668. Chemosphere 46:1457–1459. Livingstone, D.R., M.A. Kirchin, and A. Wiseman. 1989. Cytochrome p-450 and oxidative metabolism in molluscs...passive integrative sampling approach for assessing the presence and potential impacts of waterborne environmental contaminants. Chemosphere 54:695

  11. BEHAVIORAL AND PHYSIOLOGICAL RESPONSES OF DAPHNIA MAGNA, CHLORELLA VULGARIS, CORBICULA FLUMINEA, LEPOMIS MACROCHIRUS, AND VIBRO FISCHERI

    EPA Science Inventory

    The research presented here is a continuation of work designed to further the science of available and developing continuous, automated water quality monitors and how they may be most effectively deployed in a watershed management plan and/or water quality early warning system (W...

  12. BEHAVIORAL AND PHYSIOLOGICAL RESPONSES OF DAPHNIA MAGNA, CHLORELLA VULGARIS, CORBICULA FLUMINEA, LEPOMIS MACROCHIRUS, AND VIBRO FISCHERI

    EPA Science Inventory

    The research presented here is a continuation of work designed to further the science of available and developing continuous, automated water quality monitors and how they may be most effectively deployed in a watershed management plan and/or water quality early warning system (W...

  13. Laboratory and field assessment of uranium trophic transfer efficiency in the crayfish Orconectes limosus fed the bivalve C. fluminea.

    PubMed

    Simon, Olivier; Garnier-Laplace, Jacqueline

    2005-09-30

    At present, ecotoxicological information regarding the impact of natural uranium (U) on freshwater ecosystems via the trophic contamination route is scarce. We generated an experimental trophic food chain involving the prey species, Corbicula fluminea, and a predator, Orconectes limosus, for a 10-day and a 30-day feeding periods (food ration: one whole soft body/day/crayfish). We studied the efficiency of U trophic transfer and the distribution of U in the predator. During the test, we varied the quantity of dietary U (from beforehand contaminated bivalves at concentrations ranging from 0.9+/-0.1 to 20.2+/-9 microg/g fw provided to each crayfish over the 10 days) applying a daily feeding rate equal to 3.9+/-0.8% fw. The efficiency of U trophic transfer from clams to crayfish varied between 1 and 13% depending on the prey exposure modalities. Accumulation of U was observed in the digestive gland but also in gills, in the muscle, and in the molt of the crayfish after trophic exposure treatments. Under high-level exposure conditions, the digestive gland was the main target-organ, however a significant accumulation was also observed in the stomach. With regard to low levels of trophic exposure, accumulation of U in gills, in the stomach, and in the digestive gland was of the same order of magnitude. Longer exposure period which incorporated a crayfish molt, resulted in a decrease of trophic transfer ratio and a modified U tissue distribution.

  14. BEHAVIORAL AND PHYSIOLOGICAL RESPONSES OF DAPHNIA MAGNA, CHLORELLA VULGARIS, CORBICULA FLUMINEA, AND LEPOMIS MACROCHIRUS TO COPPER AND CYANIDE

    EPA Science Inventory

    The research presented here was designed to further the science of available and developing continuous, automated water quality monitors and how they may be most effectively deployed in a watershed management plan and/or water quality early warning system (WQEWS). Source waters ...

  15. Effects of elevated carbon dioxide concentrations on survivorship in zebra mussels (Dreissena polymorpha) and Asian clams (Corbicula fluminea)

    SciTech Connect

    McMahon, R.F.; Matthews, M.A.; Shaffer, L.R.; Johnson, P.D.

    1995-06-01

    In order to determine their tolerance to elevated concentrations of carbon dioxide, Asian clams and zebra mussels were collected. Subsamples of both species were acclimated to 25{degrees}C>14 days and then exposed in water at 25{degrees}C to various concentrations of CO{sub 2} and survivorship recorded. Zebra mussels were allowed to byssally attach prior to testing. Media CO{sub 2} concentrations were maintained by continuous bubbling with appropriate gas mixtures. Gas treatment included: (1) anoxia; (2) hypercapnic anoxia; and (3) hypercapnic normoxia. Deaths were recorded in subsamples of both species every 12-24 h until 100% mortality was achieved. No significant mortality occurred among specimens of either species in air bubbled control media in any experiment. Mortality time of zebra mussels exposed to anoxia under 100% N{sub 2} was 103.7 h and of Asian clams, 349.7 h. Mortality was more rapid among samples of both species exposed to anoxia under 100% CO{sub 2}, mean time to death being 43.6 h for zebra mussels and 46.3 h for Asian clams. There was no difference in the survivorship of samples of either species under atmospheres of either 5% CO{sub 2} and 95% N{sub 2} or 100% N{sub 2}, however, Asian clams survived anoxia under either atmosphere 4 to 5 times longer than did zebra mussels. There was no significant mortality among Asian clam or zebra mussel samples after a 39 day exposure to hypercapnic normoxia. While exposure to hypercapnic normoxia under an atmosphere of 5% CO{sub 2}:19% O{sub 2}:76% N{sub 2} did not induce mortality in zebra mussel samples, it completely suppressed all byssal thread production after 7 days of exposure and induced all sampled individuals to release from their byssal attachments within 10 days of exposure. These results indicate that CO{sub 2} injection may be an easily applied, cost-effective, environmentally acceptable molluscicide for mitigation and control of raw water system macrofouling by Asian clams and zebra mussels.

  16. Clams (Corbicula fluminea) as bioindicators of fecal contamination with Cryptosporidium and Giardia spp. in freshwater ecosystems in California.

    PubMed

    Miller, Woutrina A; Atwill, Edward R; Gardner, Ian A; Miller, Melissa A; Fritz, Heather M; Hedrick, Ronald P; Melli, Ann C; Barnes, Nicole M; Conrad, Patricia A

    2005-05-01

    This study evaluated clams as bioindicators of fecal protozoan contamination using three approaches: (i) clam tissue spiking experiments to compare several detection techniques; (ii) clam tank exposure experiments to evaluate clams that had filtered Cryptosporidium oocysts from inoculated water under a range of simulated environmental conditions; (iii) sentinel clam outplanting to assess the distribution and magnitude of fecal contamination in three riverine systems in California. Our spiking and tank experiments showed that direct fluorescent antibody (DFA), immunomagnetic separation (IMS) in combination with DFA, and PCR techniques could be used to detect Cryptosporidium in clam tissues. The most analytically sensitive technique was IMS concentration with DFA detection of oocysts in clam digestive gland tissues, which detected 10 oocysts spiked into a clam digestive gland 83% of the time. In the tank experiment, oocyst dose and clam collection time were significant predictors for detecting Cryptosporidium parvum oocysts in clams. In the wild clam study, Cryptosporidium and Giardia were detected in clams from all three study regions by IMS-DFA analysis of clam digestive glands, with significant variation by sampling year and season. The presence of C. parvum DNA in clams from riverine ecosystems was confirmed with PCR and DNA sequence analysis.

  17. BEHAVIORAL AND PHYSIOLOGICAL RESPONSES OF DAPHNIA MAGNA, CHLORELLA VULGARIS, CORBICULA FLUMINEA, AND LEPOMIS MACROCHIRUS TO COPPER AND CYANIDE

    EPA Science Inventory

    The research presented here was designed to further the science of available and developing continuous, automated water quality monitors and how they may be most effectively deployed in a watershed management plan and/or water quality early warning system (WQEWS). Source waters ...

  18. Active biomonitoring with Corbicula for USEPA priority pollutant and metal sources in the Anacostia River (DC, Maryland, USA).

    PubMed

    Phelps, Harriette L

    2016-07-01

    The freshwater Anacostia River watershed (Maryland, DC, USA) was surveyed for the sources of bioavailable US Environmental Protection Agency (USEPA) Priority Pollutants and toxic metals by active biomontoring (ABM) using the freshwater Asiatic clam Corbicula fluminea. The Anacostia River is a 456 km(2) tributary of the tidal freshwater Potomac River that includes the city of Washington, DC where edible fish are highly contaminated with PCBs and chlordane. From 1999 to 2011, Corbicula were collected for ABM from a Potomac reference site and translocated in cages placed at 45 sites in the tidal and nontidal Anacostia watershed. Minimum clam mortality and maximum contaminant bioaccumulation was with 2-week translocation. The clam tissues (28-50) were combined at sites and analyzed by TestAmerica for 66 USEPA Priority Pollutants plus technical chlordane, benz(e) pyrene, and 6 metals (As, Cd, Cr, Cu, Fe, Pb). Tissue contaminants reflected water, not sediment, levels. To compare sites, all contaminant data above detection or reference were grouped as total metals (TMET), total polycyclic aromatic hydrocarbons (TPAH), total PCB congeners (TPCB), total pesticides (TPEST), and total technical chlordane (TCHL). Tidal Anacostia ABM found highest TPAH and TCHL upstream at Bladensburg Marina (MD) except for TCHL at site PP near the confluence. Five nontidal MD subtributaries (94% of flow) had 17 sites with bioavailable TPAH, TPCB, or TCHL 2 to 3 times higher than found at the toxic-sediment "hotspots" near Washington. The only TMET noted was Fe at 1 site. TPAH in MD subtributaries was highest near industrial parks and Metro stations. A naphthalene spill was detected in Watts Branch. TPCB (low molecular weight) originated upstream at 1 industrial park. Total technical chlordane (80% of TPEST) was 2 to 5 times the US Food and Drug Administration action in 4 nontidal tributaries where heptachlor indicated legacy chlordane dumpsites. Total technical chlordane fell to reference

  19. Androgenesis: a review through the study of the selfish shellfish Corbicula spp.

    PubMed Central

    Pigneur, L-M; Hedtke, S M; Etoundi, E; Van Doninck, K

    2012-01-01

    Among the asexual reproductive modes, androgenesis is probably one of the most astonishing and least studied mechanisms. In this ‘paternal monopolization', the maternal nuclear genome fails to participate in zygote development and offspring are paternal nuclear clones. Obligate androgenesis is known in only a few organisms, including multiple species of clam in the genus Corbicula. Corbicula is a good system to review the evolutionary consequences of this ‘all-male asexuality' because the cytological mechanisms of androgenetic reproduction have been described. In Corbicula, sperm are unreduced and, after fertilization, the maternal nuclear chromosomes are extruded as two polar bodies. Hermaphroditic lineages of Corbicula have a worldwide distribution and seem to reproduce through androgenesis, whereas their sexual relatives have restricted ranges. The invasive success of these androgenetic Corbicula lineages may be linked to their asexual mode of reproduction. We review the phenomenon of androgenesis, focusing on evolutionary perspectives, using the genus Corbicula as an exemplar system. PMID:22473310

  20. Dietary freshwater clam (Corbicula fluminea) extract suppresses accumulation of hepatic lipids and increases in serum cholesterol and aminotransferase activities induced by dietary chloretone in rats.

    PubMed

    Chijimatsu, Takeshi; Umeki, Miki; Kobayashi, Satoru; Kataoka, Yutaro; Yamada, Koji; Oda, Hiroaki; Mochizuki, Satoshi

    2015-01-01

    We investigated the ameliorative effect of freshwater clam extract (FCE) on fatty liver, hypercholesterolemia, and liver injury in rats exposed to chloretone. Furthermore, we examined the effects of major FCE components (fat and protein fractions) to determine the active components in FCE. Chloretone increased serum aminotransferase activities and led to hepatic lipid accumulation. Serum aminotransferase activities and hepatic lipid content were lower in rats fed total FCE or fat/protein fractions of FCE. Expression of fatty acid synthase and fatty acid desaturase genes was upregulated by chloretone. Total FCE and fat/protein fractions of FCE suppressed the increase in gene expression involved in fatty acid synthesis. Serum cholesterol levels increased twofold upon chloretone exposure. Total FCE or fat/protein fractions of FCE showed hypocholesterolemic effects in rats with hypercholesterolemia induced by chloretone. These suggest that FCE contains at least two active components against fatty liver, hypercholesterolemia, and liver injury in rats exposed to chloretone.

  1. Arsenic (V) bioconcentration kinetics in freshwater macroinvertebrates and periphyton is influenced by pH.

    PubMed

    Lopez, Adeline R; Funk, David H; Buchwalter, David B

    2017-05-01

    Arsenic is an important environmental pollutant whose speciation and mobility in freshwater food webs is complex. Few studies have characterized uptake and efflux rates of arsenic in aquatic benthic invertebrates. Further, we lack a fundamental understanding of how pH influences uptake kinetics in these organisms or how this key environmental variable could alter dietary exposure for primary consumers. Here we used a radiotracer approach to characterize arsenate accumulation dynamics in benthic invertebrates, the influence of pH on uptake in a subset of these organisms, and the influence of pH on uptake of arsenate by periphyton - an important food source at the base of aquatic food webs. Uptake rate constants (Ku) from aqueous exposure were modest, ranging from ∼0.001 L g(-1)d(-1) in three species of mayfly to 0.06 L g(-1)d(-1)in Psephenus herricki. Efflux rate constants ranged from ∼0.03 d(-1) in Corbicula fluminea to ∼0.3 d(-1) in the mayfly Isonychia sp, and were generally high. Arsenate uptake decreased with increasing pH, which may be a function of increased adsorption at lower pHs. A similar but much stronger correlation was observed for periphyton where Ku decreased from ∼3.0 L g(-1)d(-1) at 6.5 pH to ∼0.7 L g(-1)d(-1) at 8.5 pH, suggesting that site specific pH could significantly alter arsenic exposure, particularly for primary consumers. Together, these findings shed light on the complexity of arsenic bioavailability and help explain observed differences reported in the literature. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Toxicity of fishery chemicals to the asiatic clam, Corbicula manilensis

    USGS Publications Warehouse

    Chandler, Jack H.; Marking, L.L.

    1979-01-01

    The Asiatic clam (Corbicula manilensis), a species introduced into U. S. waters, has spread rapidly, and its ability to survive, reproduce, and spread has caused concern. Aquatic biologists suspect that the clams may crowd out indigenous mollusks, and the animals sometimes plug water intakes and leave shell deposits that interfere with sand and gravel operations. The toxicity of 20 commonly used fishery chemicals to the Asiatic clam was determined to evaluate hazards to a nontarget aquatic invertebrate and to assess the potential of the chemicals for controlling clam populations. Among six piscicides and two lampricides tested, antimycin was most toxic to the clam; the 96-h LC50 was 0.065 mg/L. Among three therapeutants and two disinfectants tested, nifurpirinol was the most toxic; the 96-h LC50 was 7.60 mg/L. All of the compounds were less toxic to the clam than to fish. As a nontarget organism, this clam would be safe in water treated with any of the tested fishery chemicals at recommended use pattern concentrations. None of the chemicals have potential for controlling unwanted populations of these clams.

  3. Comparison of periphytic biofilm and filter-feeding bivalve metal bioaccumulation (Cd and Zn) to monitor hydrosystem restoration after industrial remediation: a year of biomonitoring.

    PubMed

    Arini, Adeline; Baudrimont, Magalie; Feurtet-Mazel, Agnès; Coynel, Alexandra; Blanc, Gérard; Coste, Michel; Delmas, François

    2011-12-01

    Despite a significant decrease in the metallic waste emissions from an industrial site and a remediation process initiated in 2007, the Riou-Mort watershed (southwest France) still exhibits high Cd and Zn concentrations. Metal wastes have long been proven to significantly disturb aquatic communities. In this study, bioaccumulation capacities and responses to the chemical improvement of the hydrosystem were assessed for a year along the contamination gradient through the comparison of two biological models: Corbicula fluminea and periphytic biofilms, both considered as good bioindicators. Bioaccumulation results confirmed the persistence of water contamination in Corbicula fluminea and biofilms with, respectively, maximum Cd concentrations reaching 80.6 and 861.2 μg gDW(-1), and Zn concentrations 2.0 and 21.3 mg gDW(-1). Biofilms exhibited bioaccumulation in close correlation with water contamination, while Corbicula fluminea presented Cd bioaccumulation clearly regulated by water temperature and metal concentrations, affecting the ventilatory activity, as revealed by condition indices measurements. Also, a linear regression using Cd bioaccumulation and temperature () showed that below approximately 6 °C Corbicula fluminea did not appear to accumulate metals. Bioconcentration factors (BCFs) were higher in biofilms in comparison with Corbicula fluminea and showed the great accumulation capacity of suspended particulate matter in biofilms. However, bioaccumulation capacities are known to be influenced by many factors other than metal concentrations, such as temperature, water oxygenation or plankton and nutrient concentrations. Thus, this study demonstrates the power of a combined assessment using both Corbicula fluminea and biofilms as bioindicators to give a more integrated view of water quality assessment. Finally, when comparing our results with previous studies, the start of hydrosystem restoration could be shown by decreasing bioaccumulation in organisms.

  4. Filter-feeding bivalves can remove avian influenza viruses from water and reduce infectivity

    USDA-ARS?s Scientific Manuscript database

    Avian influenza (AI) viruses are transmitted within wild aquatic bird populations through an indirect fecal-oral route involving fecal-contaminated water. In this study, the influence of filter-feeding bivalves, Corbicula fluminea, on the infectivity of AI virus in water was examined. A single cla...

  5. Detection system of Cryptosporidium parvum oocysts by brackish water benthic shellfish (Corbicula japonica) as a biological indicator in river water.

    PubMed

    Izumi, T; Yagita, K; Endo, T; Ohyama, T

    2006-11-01

    The brackish water benthic shellfish, Corbicula japonica, was experimentally exposed to Cryptosporidium parvum oocysts at 1.51x10(4)oocysts/clam/day for 7 or 14 days. Oocysts were predominantly eliminated through the feces of Corbicula japonica in both cases by microscopic and PCR methods. The fecal excretion rates of oocysts within 4 days after the last exposure to Corbicula japonica were 87.6% for the 7-day exposure group and 86.0% for the 14-day exposure group. The tissue residue level of oocysts in the gastrointestinal tract 3 days after the last exposure was 2.7% of total exposed oocysts and that of 7 days was 1.1% for the 7-day exposure case and 1.6 and 0.5% for the 14-day exposure case, respectively, maintaining infectivity to cultured cells (HCT-8) in vitro. At the same time, field tests of Corbicula japonica for collecting oocysts showed that this clam could certainly collect Cryptosporidium parvum oocysts in the natural river and, furthermore, the gene type of C. parvum could be also identified proving its effectiveness as a biological indicator. The present study showed that the brackish water benthic shellfish Corbicula japonica may be capable of gathering and preserving Cryptosporidium parvum oocysts to a considerable extent under the natural ecological conditions, and further suggests the effectiveness of Corbicula japonica as a practical and general bioindicator for estimates of river water contamination by oocysts of Cryptosporidium parvum.

  6. Small subunit ribosomal DNA suggests that the xenophyophorean Syringammina corbicula is a foraminiferan.

    PubMed

    Pawlowski, Jan; Holzmann, Maria; Fahrni, Jose; Richardson, Susan L

    2003-01-01

    Xenophyophorea are giant deep-sea rhizopodial protists of enigmatic origins. Although species were described as Foraminifera or sponges in the early literature, the xenophyophoreans are currently classified either as a class of Rhizopoda or an independent phylum. To establish the phylogenetic position of Xenophyophorea, we analysed the small subunit (SSU) rRNA gene sequence of Syringammina corbicula Richardson, a newly described xenophyophorean species from the Cape Verde Plateau. The SSUrDNA analyses showed that S. corbicula is closely related to Rhizammina algaeformis, a tubular deep-sea foraminiferan. Both species branch within a group of monothalamous (single-chambered) Foraminifera, which include also such agglutinated genera as Toxisarcon, Rhabdammina, and Saccammina, and the organic-walled genera Gloiogullmia and Cylindrogullmia. Our results are congruent with observations of similar cytoplasmic organisation in Rhizammina and Syringammina. Thus, the Xenophyophorea appear to be a highly specialised group of deep-sea Foraminifera.

  7. Climate controls the distribution of a widespread invasive species: Implications for future range expansion

    USGS Publications Warehouse

    McDowell, W.G.; Benson, A.J.; Byers, J.E.

    2014-01-01

    1. Two dominant drivers of species distributions are climate and habitat, both of which are changing rapidly. Understanding the relative importance of variables that can control distributions is critical, especially for invasive species that may spread rapidly and have strong effects on ecosystems. 2. Here, we examine the relative importance of climate and habitat variables in controlling the distribution of the widespread invasive freshwater clam Corbicula fluminea, and we model its future distribution under a suite of climate scenarios using logistic regression and maximum entropy modelling (MaxEnt). 3. Logistic regression identified climate variables as more important than habitat variables in controlling Corbicula distribution. MaxEnt modelling predicted Corbicula's range expansion westward and northward to occupy half of the contiguous United States. By 2080, Corbicula's potential range will expand 25–32%, with more than half of the continental United States being climatically suitable. 4. Our combination of multiple approaches has revealed the importance of climate over habitat in controlling Corbicula's distribution and validates the climate-only MaxEnt model, which can readily examine the consequences of future climate projections. 5. Given the strong influence of climate variables on Corbicula's distribution, as well as Corbicula's ability to disperse quickly and over long distances, Corbicula is poised to expand into New England and the northern Midwest of the United States. Thus, the direct effects of climate change will probably be compounded by the addition of Corbicula and its own influences on ecosystem function.

  8. Asiatic clam (Corbicula manilensis) and other foods used by waterfowl in the James River, Virginia

    USGS Publications Warehouse

    Perry, M.C.; Uhler, F.M.

    1981-01-01

    Corbicula manilensis was found in the gizzards of 24 ducks of 5 species taken from the James River, Virginia, between 1973 and 1976. Percent average volume in these species ranged from trace to 6%. This is the first known occurrence of this exotic clam in the food of duck in Chesapeake Bay. A total of 135 other food items was identified from the 116 gizzards of 9 species that were examined. Food that predominated included Cyperus spp., Leersia oryzoides, Polygonum spp., and Zea mays. The great diversity of food consumed in this fresh tidal section of the James River indicates the high value of these wetlands to waterfowl.

  9. Annual harvests of Corbicula populations prevent clogging of nuclear reactor heat exchangers

    SciTech Connect

    Harvey, R.S.

    1983-01-01

    An annual program for removal of millions of Corbicula from upstream cooling water basins has prevented reclogging of nuclear reactor heat exchanger distributor plates at the Savannah River Plant during the past seven years. There are nine 32-megaliter basins in the three operating reactor areas where some settling of particulates occurs before cooling water is passed through screens in route to heat exchangers. Annual cleanings keep silt/clam substrate levels low and clam sizes small. Data are presented on the size/age distribution for clams recolonizing basins between cleanings.

  10. Influence of Methylmercury from Tributary Streams on Mercury Levels in Savannah River Asiatic Clams

    SciTech Connect

    Paller, M.H.

    2004-03-01

    Average methylmercury levels in five Savannah River tributary streams sampled 11 times over two years were nearly twice as high as in the Savannah River. Total mercury levels in the tributaries did not differ significantly from the river. All of the tributaries drained extensive wetlands that would be expected to support comparatively high rates of methylation. Mercury concentrations in Asiatic clams (Corbicula fluminea) collected from the discharge plumes of Savannah River tributaries were significantly higher than in Asiatic clams collected from the Savannah River upstream from the tributary mouths . These results indicate that streams draining wetlands into coastal plain rivers can create localized areas of elevated methylmercury with resulting increases in the mercury levels of river biota.

  11. Distribution of platinum and other traffic related metals in sediments and clams (Corbicula sp.).

    PubMed

    Ruchter, Nadine; Sures, Bernd

    2015-03-01

    Platinum is part of traffic-emitted metals since the introduction of automotive catalyst converters. Still, automobile emissions are one of the major sources for metals in European river systems. However, field data on Pt is scarce and there is a lack of knowledge concerning the distribution and biological availability of Pt. Therefore, the distribution of traffic related metals (Cd, Cr, Cu, Ni, Pb, Pt, and Zn) was analyzed in sediment samples and in the Asian clam Corbicula sp. Samples were taken from three transects following road runoff inlets. Pt was introduced into the river by road runoff. The highest Pt concentrations in sediments were analyzed in the silt/clay fraction (45 ng/g), while the highest total Pt burden was obtained for the sand fraction, that makes up more than 60% of the sediment. Metal concentrations were related to the area of the drained street section as well as to their distance from the discharge point, and to grain size distribution within the sediment. Pt and other traffic related metals were accumulated by clams. Due to the feeding behavior of the freshwater mussel Corbicula sp. Pt concentrations in the soft tissue remain relatively low (max Pt concentration: 1.3 ng/g freeze dried soft tissue) and acute lethal or toxic effects therefore appear to be unlikely. Nonetheless, chronic exposure effects still have to be examined.

  12. Remobilization and bioavailability of cadmium from historically contaminated sediments: influence of bioturbation by tubificids.

    PubMed

    Ciutat, Aurélie; Gerino, Magali; Boudou, Alain

    2007-09-01

    The effects of bioturbation by tubificids on cadmium (Cd) remobilization and bioavailability from sediment were studied throughout two experiments. With bioturbation, particulate Cd was transitorily released into the overlying water, in correlation with sediment resuspension (maximum of 6.1+/-0.1 microg L(-1) after 6 days). Cd bioaccumulation by the bivalve Corbicula fluminea was very limited (maximum of 1.73+/-0.34 microg g(-1), dw), and independent of the algae diet. In contrast, without bioturbation, the release of dissolved Cd increased with the duration of the experiments (maximum of 9.9+/-0.8 microg L(-1) after 36 days). Cd bioaccumulation by C. fluminea varied according to their diet: low bioaccumulation when no algae were added (2.18+/-0.29 microg g(-1), dw), higher bioaccumulation when algae were added throughout the experiment (8.52+/-1.61 microg g(-1), dw), and the highest bioaccumulation when algae were added only during the last 10 days of the experiment (19.66+/-4.63 microg g(-1), dw).

  13. Bioconcentration and biotransformation of [¹⁴C]methoxychlor in the brackish water bivalve Corbicula japonica.

    PubMed

    Masuda, Minoru; Ohyama, Kazutoshi; Hayashi, Osamu; Satsuma, Koji; Sato, Kiyoshi

    2011-09-01

    To obtain basic information on the metabolic fate of xenobiotics in the brackish water, bivalve Corbicula japonica, bioconcentration and biotransformation experiments were performed using methoxychlor (MXC) as a model compound. Bivalves were exposed to [ring-U-¹⁴C]MXC (10 µg L⁻¹) for 28 days under semi-static conditions followed by a 14-day depuration phase. The ¹⁴C concentration in the bivalves rapidly increased and reached a steady state after exposure for 7 days (BCFss = 2010); however, it rapidly decreased with a half-life of 2.2 days in the depuration phase. Mono- and bis-demethylated MXC, and their corresponding sulphate conjugates, were identified as minor metabolites. No glycoside conjugates (including glucuronide and glucoside) were detected. Despite this biotransformation system, bivalves were found to excrete retained MXC mostly unchanged although its relatively hydrophobic nature.

  14. Detection of tdh and trh genes in Vibrio parahaemolyticus isolated from Corbicula moltkiana prime in West Sumatera, Indonesia.

    PubMed

    Marlina; Radu, Son; Kqueen, Cheah Yoke; Napis, Suhaimi; Zakaria, Zunita; Mutalib, Sahilah Abd; Nishibuchi, Mitsuaki

    2007-03-01

    The occurrence of Vibrio parahaemolyticus in raw Corbicula moltkiana Prime from Lake Singkarak and Pasar Raya Padang market and in cooked samples in West Sumatera, Indonesia, was studied. Thirteen raw and seven cooked bivalve samples were positive using CHROMAgar Vibrio medium. All 47 V parahaemolyticus isolates were positive for toxR gene but negative for trh. However, 36% (17/47) of V parahaemolyticus strains were positive for tdh gene. Antibiotic profiling showed that 76% and 38% of isolates from raw and cooked bivalves respectively were resistant to ampicillin. Using RAPD-PCR analysis, most of the strains were clustered according to their source of isolation but some of the strains from raw and cooked samples were clustered together. These results indicate that pathogenic V parahaemolyticus isolates are present in Corbicula moltkiana Prime in West Sumatera, Indonesia, suggesting that V parahaemolyticus may also be present in seafood in other regions of Indonesia.

  15. Linking terrestrial and estuarine ecosystems: Organic matter sources supporting the high secondary production of a non-indigenous bivalve

    EPA Science Inventory

    The Asian clam Corbicula fluminea is one of the most pervasive species in freshwater ecosystems. Our objective was to characterize the trophic interactions of C. fluminea in the Minho river estuary (NW-Iberian Peninsula, Europe), an estuarine ecosystem in which C. fluminea presen...

  16. Linking terrestrial and estuarine ecosystems: Organic matter sources supporting the high secondary production of a non-indigenous bivalve

    EPA Science Inventory

    The Asian clam Corbicula fluminea is one of the most pervasive species in freshwater ecosystems. Our objective was to characterize the trophic interactions of C. fluminea in the Minho river estuary (NW-Iberian Peninsula, Europe), an estuarine ecosystem in which C. fluminea presen...

  17. Molecular cloning of glycoside hydrolase family 45 cellulase genes from brackish water clam Corbicula japonica.

    PubMed

    Sakamoto, Kentaro; Toyohara, Haruhiko

    2009-04-01

    We previously reported endogenous Glycoside Hydrolase Family (GHF) 9 beta-1,4-glucanase gene, CjCel9A, from common Japanese freshwater clam Corbicula japonica. Here we identified another endogenous beta-1,4-glucanase genes which belong to GHF45 (CjCel45A, CjCel45B). Both genes encode ORF of 627 bp corresponding to 208 amino acids. CjCel45A and CjCel45B are different in 5' and 3'-untranslated regions and six nucleotides in the ORF. CjCEL45 has only one GHF45 catalytic domain without any carbohydrate binding modules as is the case with other molluskan GHF45 enzymes. Phylogenetic analysis and genomic structure of CjCel45 gene implies that this gene is likely to be acquired from fungi by common ancestor of mollusks. Reverse transcription (RT)-PCR analysis and in situ hybridization revealed that CjCel45A is likely to be expressed in the secretory cells in the digestive gland, suggesting that this cellulase is produced in the same site as CjCEL9A. CjCEL45A was successfully expressed in E. coli cells and zymographic analysis of the recombinant CjCEL45A showed that CjCEL45A is a functional beta-1,4-glucanase. The finding of multiple cellulase genes in C. japonica strongly supports our hypothesis that this species function as a cellulose decomposer in estuarine environments.

  18. Factors affecting growth and survival of the asiatic clam Corbicula sp. under controlled laboratory conditions

    SciTech Connect

    Double, D.D.; Daly, D.S.; Abernethy, C.S.

    1983-04-01

    Growth of Corbicula sp. was determined in relation to food supply, water temperature, and clam size as an aid to researchers conducting chronic effects toxicity studies. Water temperatures for the two 84-day test series were 10, 20, and 30/sup 0/C. Linear models provided good relationships (r/sup 2/ > 0.90) between clam shell length (SL), total weight (TW), and wet/dry tissue weights. Clam growth was minimal during low phytoplankton densities (approx. 300 cells/ml), and all three size groups lost weight at 20 and 30/sup 0/C. Mortality of small clams at 30/sup 0/C was 100% after 71 days. At phytoplankton densities > 1000 cells/ml, overall differences in growth with respect to clam size and temperature were detectable at p < 0.01; growth of all clam groups was greatest at 30/sup 0/C. Small clams exhibited the greatest absolute increase in mean shell length at all test temperatures, and weight gains were similar to those of medium and large clams.

  19. Effects of copper on adult and early life stages of the freshwater clam, Corbicula manilensis

    SciTech Connect

    Harrison, F.L.; Knezovich, J.P.; Rice, D.W. Jr.

    1981-09-01

    The copper sensitivity of adult and larval stages of the freshwater clam Corbicula manilensis was evaluated. In addition, copper concentrations in adult clams exposed for 4 to 10 wks to copper in a high-volume, flow-through bioassay are determined. The response of these clams to copper depended on life stage. Copper sensitivity of larvae decreased markedly in successive developmental stages. The LC50/sub 24/s of veliger and juvenile larve were 28 and 600 ..mu..g Cu/L, respectively. The mortality of trochophore larvae exposed to 10 ..mu..g Cu/L for 1 h was 91.5%. The sensitivity to copper decreased with the amount of larval shell deposition. Adult clams were resistant to copper; the LC50/sub 96/ was greater than 2600 ..mu..g Cu/L. By comparison the incipient concentration (ILC) was low - less than 10 ..mu..g Cu/L. Adult clams accumulated more copper as copper concentrations in the water increased. Evidence for copper loss near or at death was obtained.

  20. Accumulation of trace elements, pesticides, and polychlorinated biphenyls in sediments and the clam Corbicula manilensis of the Apalachicola River, Florida

    USGS Publications Warehouse

    Elder, J.F.; Mattraw, H.C.

    1984-01-01

    A survey of trace element and synthetic organic compound concentrations in botton materials was conducted on the Apalachichola River in northwest Florida in 1979-80 as part of the Apalachicola River Quality Assessment. Substances analyzed included trace elements (predominantly heavy metals), organochlorine insecticides, organophosphorus insecticides, chlorinated phenoxy-acid herbicides, and polychlorinated biphenyls (PCBs). Three kinds of materials were surveyed: fine-grained sediments, whole-body tissue of the Asiatic clam Corbicula manilensis, and bottom-load organic detritus. No hazardous levels of any of the substances were found. Concentrations in the fine-grained sediments and clams were generally at least ten times lower than maximum limits considered safe for biota of aquatic systems. A comparison of trace-substance data from the Apalachicola River with data from Lake Seminole (upstream) and Apalachicola Bay (downstream) showed lower concentrations in riverine clams. Sediment concentrations in all parts of the system were comparable. Most trace substances in the Apalachicola River enter the river from the upstream part of the basin (the Chattahoochee and Flint Rivers in Georgia and Alabama) and from nonpoint sources throughout the basin. There are no major point discharges along the Apalachicola. Trend analysis was limited by the scope of the study, but did not reveal any spatial or temporal trends in concentrations of any of the substances analyzed. Concentrations of organic compounds and most metals in Corbicula manilensis did not correlate with those in sediments.

  1. Accumulation and tissue distribution of radioiodine ( sup 131 I) from algal phytoplankton by the freshwater clam Corbicula manilensis

    SciTech Connect

    Cuvin-Aralar, Ma.L.A. ); Umaly, R.C. )

    1991-12-01

    Radioactive wastes discharged from establishments involved in the use of radioisotopes such as nuclear-powered industries, tracer research and nuclear medicine are a potential public health hazard. Such wastes contain radionuclides, particularly Iodine-131 ({sup 131}I), produced in fission with a yield of about 3%. Radionuclides in waste waters are known to be taken up by molluscs such as mussels, oysters, and clams. This study aims to determine the uptake of {sup 131}I from algal phytoplankton (Chroococcus dispersus) fed to the freshwater clam Corbicula manilensis as well as the organ/tissue distribution. The results will be compared with a previous study on {sup 131}I uptake from water by the same clams.

  2. Assimilation of terrigenous organic matter via bacterial biomass as a food source for a brackish clam, Corbicula japonica (Mollusca: Bivalva)

    NASA Astrophysics Data System (ADS)

    Yamanaka, Toshiro; Mizota, Chitoshi; Maki, Yonosuke; Matsumasa, Masatoshi

    2013-07-01

    Corbicula japonica collected from the Kitakami River estuary, northeastern Japan, showed lower δ34S values in soft-body parts (+1.7 to +11.0‰) than the ambient seawater sulfate sulfur (+21‰), and this value gradually decreased at successive sites up to 15.8 km upstream from the river mouth. Previous study using carbon and nitrogen isotopes suggests that the bivalve nonselectively assimilates particulate organic matter of marine and terrestrial origin by filter feeding. This pattern in δ34S values may indicate a considerable contribution of a food source derived from terrigenous organic matter, which has low δ34S values close to 0‰, and the bivalve has been reported to have cellulase and hemicellulase activities. Unique fatty acids (iso 17:0 and anteiso 17:0 acids), both characteristic of sulfate-reducing bacteria, were observed in the salt-free, soft-body parts of the bivalve. The concentration of monounsaturated fatty acids, possibly derived from bacteria, was also high. Trace amounts of a polyunsaturated fatty acid (20:5ω3) specific to dinoflagellates were detected. In Corbicula habitats, reductive sandy layers with ample sulfides that were sporadically intercalated into the oxidative sandy sediment were often observed. The stable isotopic signatures of sediment sulfides (acid-volatile sulfide) and associated pore-water sulfates were -8.9 to +8.6‰ and +22.4 to +26.3‰, respectively, indicating the existence of bacterial sulfate-reducing activity and thiobios biomass. These isotopic signatures of the sediment, with the fatty acid composition of the bivalve, confirm the importance of a food source derived from bacteria belonging to the thiobios in the substrate sediments via pedal feeding, rather than direct digestion of terrigenous organic matter, in this estuarine ecosystem.

  3. Dynamic changes in the accumulation of metabolites in brackish water clam Corbicula japonica associated with alternation of salinity.

    PubMed

    Koyama, Hiroki; Okamoto, Seiji; Watanabe, Naoki; Hoshino, Naoshige; Jimbo, Mitsuru; Yasumoto, Ko; Watabe, Shugo

    2015-03-01

    The brackish water clam Corbicula japonica inhabits rivers and brackish waters throughout Japan where the major fishing grounds in the Ibaraki Prefecture, Japan, are located at the Hinuma Lake and Hinuma River. Water salinity in the Lake Hinuma is low and stable due to the long distance from the Pacific Ocean, whereas that in the downstream of the river varies daily due to a strong effect of tidal waters. In the present study, we dissected the gill and foot muscle of brackish water clam collected from these areas, and subjected them to metabolome analysis by capillary electrophoresis-time-of-flight mass spectrometry. More than 200 metabolites including free amino acids, peptides and organic acids were identified, and their amounts from the foot muscle tend to be higher than those from the gill. The principal component analysis revealed that the amount of each metabolite was different among sampling areas and between the gill and foot muscle, whereas no apparent differences were observed between male and female specimens. When the metabolites in the female clam at high salinity were compared with those at low salinity, concentrations of β-alanine, choline, γ-aminobutyric acid, ornithine and glycine betaine were found to be changed in association with salinity. We also compared various metabolites in relation to metabolic pathways, suggesting that many enzymes were involved in their changes depending on salinity. Copyright © 2014 Elsevier Inc. All rights reserved.

  4. Accumulative characteristics of pesticide residues in organs of bivalves (Anodonta woodiana and Corbicula leana) under natural conditions.

    PubMed

    Uno, S; Shiraishi, H; Hatakeyama, S; Otsuki, A; Koyama, J

    2001-01-01

    Accumulative characteristics of pesticide residues in the gill, midgut gland, gonad, and the remaining tissues of the bivalve mollusks Anodonta woodiana and Corbicula leana were examined during the rice planting seasons of 1992 and 1994. Although seven pesticides, except thiobencarb, were accumulated all at ppb levels in the midgut gland (liver) and gonad of both bivalves during their application period, thiobencarb was accumulated in C. leana at extremely high levels of 15.70 microg g(-1) in 1992 and 12.45 microg g(-1) in 1994 in the midgut gland and 15.80 microg g(-1) in 1992 and 16.40 microg g(-1) in 1994 in the gonad, respectively. These levels were about 100 times higher than those in A. woodiana. Thiobencarb and molinate in A. woodiana and chlornitrofen (CNP) and molinate in C. leana remained in the gonad and midgut gland longer than in the gill and remaining tissues, while thiobencarb in organs of C. leana remained at ppm levels until the end of the experiments. The present study suggests that these interspecies differences can be attributed to differences between the two species in their ability to eliminate pesticides.

  5. Closeout of IE Bulletin 81-03: flow blockage of cooling water to safety system components by Corbicula sp. (Asiatic clam) and Mytilus sp. (mussel)

    SciTech Connect

    Rains, J.H.; Foley, W.J.; Hennick, A.

    1984-06-01

    On April 10, 1981, the Office of Inspection and Enforcement (IE) of the U.S. Nuclear Regulatory Commission (NRC) issued Bulletin 81-03 requiring all nuclear generating unit licensees to assess the potential for biofouling of safety-related system components as a result of Asiatic clams (Corbicula sp.) and marine mussels (Mytilus sp.). An assessment of the areal extent of Asiatic clam and marine mussel infestation has been made along with an evaluation of detection and control procedures currently in use by licensees. Recommendations are provided with regard to adequacy of detection, inspection and prevention practices currently in use, biocidal treatment programs, and additional areas of concern. Safety implications and licensee responsibilities are discussed. Of 79 facilities licensed to operate, 17 have reported biofouling problems, 21 are judged to have high biofouling potential, 17 are judged to have low or future potential, and 24 are judged to have little or no potential. For 49 facilities under construction, the number of units for matching conditions of biofouling are 3, 25, 15, and 6 in the same decreasing order of severity.

  6. Microcystin uptake and biochemical responses in the freshwater clam Corbicula leana P. exposed to toxic and non-toxic Microcystis aeruginosa: Evidence of tolerance to cyanotoxins.

    PubMed

    Pham, Thanh-Luu; Shimizu, Kazuya; Dao, Thanh-Son; Hong-Do, Lan-Chi; Utsumi, Motoo

    2015-01-01

    We investigated the accumulation and adverse effects of toxic and non-toxic Microcystis in the edible clam Corbicula leana. Treated clams were exposed to toxic Microcystis at 100 μg of MC (microcystin)-LReq L(-1) for 10 days. The experimental organism was then placed in toxin-free water and fed on non-toxic Microcystis for the following 10 days for depuration. Filtering rates (FRs) by C. leana of toxic and non-toxic Microcystis and of the green alga Chlorella vulgaris as a control were estimated. Adverse effects were evaluated though the activity of catalase (CAT), superoxide dismutase (SOD) and glutathione S-transferase (GST). Clam accumulated MCs (up to 12.7 ± 2.5 μg g(-1) dry weight (DW) of free MC and 4.2 ± 0.6 μg g(-1) DW of covalently bound MC). Our results suggest that although both toxic and non-toxic cyanobacteria caused adverse effects by inducing the detoxification and antioxidant defense system, the clam was quite resistant to cyanotoxins. The estimated MC concentration in C. leana was far beyond the World Health Organization's (WHO) provisional tolerable daily intake (0.04 μg kg(-1) day(-1)), suggesting that consuming clams harvested during cyanobacterial blooms carries a high health risk.

  7. Preliminary results from a shallow water benthic grazing study

    USGS Publications Warehouse

    Jones, N.L.; Monismith, Stephen G.; Thompson, Janet K.

    2005-01-01

    Despite great improvements in our knowledge on the effects of benthic grazers on seston concentrations in water columns, the effects of different hydrodynamic conditions on grazing rates has not been formulated. This makes it difficult to assess the system-wide effect of the benthic ecosystem on phytoplankton concentrations. Furthermore, it affects our ability to predict the potential success of a benthic species, such as the invasive clams Corbicula fluminea and Potamocorbula amurensis. This paper presents the preliminary results of a control volume approach to elucidate the effect of different hydrodynamic conditions on the grazing rates of Corbicula fluminea.

  8. Application of Fenton oxidation to reduce the toxicity of mixed parabens.

    PubMed

    Martins, Rui C; Gmurek, Marta; Rossi, André F; Corceiro, Vanessa; Costa, Raquel; Quinta-Ferreira, M Emília; Ledakowicz, Stanislaw; Quinta-Ferreira, Rosa M

    2016-10-01

    The aims of the present work were to assess the application of a chemical process to degrade a mixture of parabens and determine the influence of a natural river water matrix on toxicity. Model effluents containing either a single compound, namely methylparaben, ethylparaben, propylparaben, butylparaben, benzylparaben or p-hydroxybenzoic acid, or to mimic realistic conditions a mixture of the six compounds was used. Fenton process was applied to reduce the organic charge and toxic properties of the model effluents. The efficiency of the decontamination has been investigated using a chemical as well as a toxicological approach. The potential reduction of the effluents' toxicity after Fenton treatment was evaluated by assessing (i) Vibrio fischeri luminescence inhibition, (ii) lethal effects amongst freshwater Asian clams (Corbicula fluminea), and (iii) the impact on mammalian neuronal activity using brain slices. From the environmental point of view such a broad toxicity analysis has been performed for the first time. The results indicate that Fenton reaction is an effective method for the reduction of chemical oxygen demand of a mixture of parabens and their toxicity to V. fischeri and C. fluminea. However, no important differences were found between raw and treated samples in regard to mammalian neuronal activity.

  9. Structure and spatial patterns of macrobenthic community in Tai Lake, a large shallow lake, China

    USGS Publications Warehouse

    Di Li,; Erickson, Richard A.; Song Tang,; Xuwen Li,; Niu, Zhichun; Xia Wang,; Hongling Liu,; Hongxia Yu,

    2016-01-01

    Tai Lake (Chinese: Taihu), the third-largest freshwater lake in China, suffers from harmful cyanobacteria blooms that are caused by economic development and population growth near the lake. Several studies have focused on phytoplankton in Tai Lake after a drinking water crisis in 2007; however, these studies primarily focused on microcystin bioaccumulation and toxicity to individual species without examining the effects of microcystin on macrobenthic community diversity. In this study, we conducted a survey of the lake to examine the effects of microcystine and other pollutants on marcobenthic community diversity. A totally of forty-nine species of macroinvertebrates were found in Tai Lake. Limnodrilus hoffmeisteri and Corbicula fluminea were the most abundant species. Cluster-analysis and one-way analysis of similarity (ANOSIM) identified three significantly different macrobenthic communities among the sample sites. More specifically, sites in the eastern bays, where aquatic macrophytes were abundant, had the highest diversity of macrobenthic communities, which were dominated by Bellamya aeruginosa, Bellamya purificata, L. hoffmeisteri, and Alocinma longicornis. Sites in Zhushan Bay contained relatively diverse communities, mainly composed of L. hoffmeisteri, C. fluminea, L. claparederanus, R. sinicus, and Cythura sp. Sites in the western region, Meiliang Bay and Wuli Bay had the lowest diversity, mainly composed ofL. hoffmeisteri, C. fluminea, Branchiura sowerbyi, and Rhyacodrilus sinicus. In addition, the relationships between macrobenthic metrics (Shannon–Wiener, Margalef, and Pielou) and environmental variables showed that community structure and spatial patterns of macrobenthos in Tai Lake were significantly influenced by chemical oxygen demand (CODCr), biochemical oxygen demand (BOD5), lead (Pb), and microcystin-LR (L for leucine and R for arginine). Our findings provide critical information that could help managers and policymakers

  10. Assessing the potential of the European Atlantic sturgeon Acipenser sturio to control bivalve invasions in Europe.

    PubMed

    Ferreira-Rodriguez, N; Gessner, J; Pardo, I

    2016-08-01

    This pilot study explored the potential of juvenile European Atlantic sturgeon Acipenser sturio to feed on two invasive bivalve species, the Asian clam Corbicula fluminea and the Eurasian zebra mussel Dreissena polymorpha. Preliminary results indicate that native A. sturio were feeding on D. polymorpha at a very limited rate and their potential to prevent the establishment of invasive bivalve species, in new and previously invaded areas, is considered limited. © 2016 The Fisheries Society of the British Isles.

  11. Field Testing of Activated Carbon Mixing and In Situ Stabilization of PCBs in Sediment at Hunters Point Shipyard Parcel F, San Francisco Bay, California

    DTIC Science & Technology

    2008-08-01

    Luthy. Biodynamic Modeling of PCB Uptake by Macoma balthica and Corbicula fluminea from Sediment Amended with Activated Carbon . Environmental...Activated Carbon Mixing and In Situ Stabilization of PCBs in Sediment at Hunters Point Shipyard Parcel F, San Francisco Bay, California August 2008...2008 2. REPORT TYPE N/A 3. DATES COVERED - 4. TITLE AND SUBTITLE Field Testing of Activated Carbon Mixing and In Situ Stabilization of PCBs in

  12. In vitro test systems supporting the development of improved pest control methods: a case study with chemical mixtures and bivalve biofoulers.

    PubMed

    Silva, Carlos; Nunes, Bruno; Nogueira, António Ja; Gonçalves, Fernando; Pereira, Joana L

    2016-11-01

    Using the bivalve macrofouler Corbicula fluminea, the suitability of in vitro testing as a stepping stone towards the improvement of control methods based on chemical mixtures was addressed in this study. In vitro cholinesterase (ChE) activity inhibition following single exposure of C. fluminea tissue to four model chemicals (the organophosphates dimethoate and dichlorvos, copper and sodium dodecyl phosphate [SDS]) was first assessed. Consequently, mixtures of dimethoate with copper and dichlorvos with SDS were tested and modelled; mixtures with ChE revealed synergistic interactions for both chemical pairs. These synergic combinations were subsequently validated in vivo and the increased control potential of these selected combinations was verified, with gains of up to 50% in C. fluminea mortality relative to corresponding single chemical treatments. Such consistency supports the suitability of using time- and cost-effective surrogate testing platforms to assist the development of biofouling control strategies incorporating mixtures.

  13. Filter-feeding bivalves can remove avian influenza viruses from water and reduce infectivity

    PubMed Central

    Faust, Christina; Stallknecht, David; Swayne, David; Brown, Justin

    2009-01-01

    Avian influenza (AI) viruses are believed to be transmitted within wild aquatic bird populations through an indirect faecal–oral route involving contaminated water. This study examined the influence of filter-feeding bivalves, Corbicula fluminea, on the infectivity of AI virus in water. Clams were placed into individual flasks with distilled water inoculated 1:100 with a low pathogenic (LP) AI virus (A/Mallard/MN/190/99 (H3N8)). Viral titres in water with clams were significantly lower at 24 and 48 h post-inoculation compared to LPAI-infected water without clams. To determine whether clams affected the infectivity of AI viruses, 18 wood ducks (Aix sponsa) were divided into test groups and inoculated with a variety of treatments of clam supernatants, whole clams and water exposed to a high pathogenic (HP) AI (A/whooper swan/Mongolia/244/05 (H5N1)). None of the wood ducks inoculated with HPAI-infected water that was filtered by clams or that was inoculated with or fed tissue from these clams exhibited morbidity or mortality. All wood ducks exposed to either HPAI-infected water without clams or the original viral inoculum died. These results indicate that filter-feeding bivalves can remove and reduce the infectivity of AI viruses in water and demonstrate the need to examine biotic environmental factors that can influence AI virus transmission. PMID:19656788

  14. Filter-feeding bivalves can remove avian influenza viruses from water and reduce infectivity.

    PubMed

    Faust, Christina; Stallknecht, David; Swayne, David; Brown, Justin

    2009-10-22

    Avian influenza (AI) viruses are believed to be transmitted within wild aquatic bird populations through an indirect faecal-oral route involving contaminated water. This study examined the influence of filter-feeding bivalves, Corbicula fluminea, on the infectivity of AI virus in water. Clams were placed into individual flasks with distilled water inoculated 1:100 with a low pathogenic (LP) AI virus (A/Mallard/MN/190/99 (H3N8)). Viral titres in water with clams were significantly lower at 24 and 48 h post-inoculation compared to LPAI-infected water without clams. To determine whether clams affected the infectivity of AI viruses, 18 wood ducks (Aix sponsa) were divided into test groups and inoculated with a variety of treatments of clam supernatants, whole clams and water exposed to a high pathogenic (HP) AI (A/whooper swan/Mongolia/244/05 (H5N1)). None of the wood ducks inoculated with HPAI-infected water that was filtered by clams or that was inoculated with or fed tissue from these clams exhibited morbidity or mortality. All wood ducks exposed to either HPAI-infected water without clams or the original viral inoculum died. These results indicate that filter-feeding bivalves can remove and reduce the infectivity of AI viruses in water and demonstrate the need to examine biotic environmental factors that can influence AI virus transmission.

  15. Tracing Cadmium in the Environment: an Evolving Stable Isotope Approach

    NASA Astrophysics Data System (ADS)

    Bullen, T. D.; Bouse, R. M.; Brown, C. L.; Croteau, M.; Luoma, S. N.; Topping, B. R.

    2005-05-01

    Cadmium (Cd) is a trace constituent in rocks and waters, and like many transition metals is an essential dietary nutrient at low levels but highly toxic in elevated doses. In many respects, cadmium behaves chemically like calcium (Ca) and thus substitutes for Ca in liquid-solid partitioning reactions and generally follows Ca through biogeochemical cycles and metabolic processes. Cd is comprised of 8 stable isotopes, and given the isotopic systematics of environmental Ca it is likely that variations in the stable isotope composition of Cd in natural materials will result from both inorganic and biologic processes. In order to assess the potential of Cd isotope variations to reveal information about sources, metabolic and biogeochemical pathways and fates of environmental Cd, we have initiated a broad study of the stable isotope composition of Cd in a variety of natural and anthropogenically-influenced systems. As an example, here we report the results of the first systematic study of the stable isotope composition of Cd in biologic materials. We focused on the isotopic variability of Cd in tissues of two species of clam collected from the San Francisco Bay estuary, Potamocorbula amurensis which resides in brackish water and Corbicula fluminea which resides in fresh and slightly brackish water. Both clam species concentrate Cd in their soft and hard tissues. During both low-flow conditions in August and high-flow conditions in April, δ116Cd of soft tissues of Potamocorbula was consistently negative and increased down-estuary with increasing salinity (δ116Cd is defined as the per mil difference of the 116Cd/110Cd ratio between a sample and our standard, igneous rock BIR-1). Samples collected in August were systematically displaced to higher δ116Cd than those collected in April. Soft tissues of Corbicula collected in both August and April from upstream, fully fresh-water sampling sites had identical δ116Cd, while soft tissues of Corbicula collected from our site at

  16. Stable metal isotopes reveal copper accumulation and loss dynamics in the freshwater bivalve Corbucula

    USGS Publications Warehouse

    Croteau, M.-N.; Luoma, S.N.; Topping, B.R.; Lopez, C.B.

    2004-01-01

    Characterization of uptake and loss dynamics is critical to understanding risks associated with contaminant exposure in aquatic animals. Dynamics are especially important in addressing questions such as why coexisting species in nature accumulate different levels of a contaminant. Here we manipulated copper (Cu) stable isotopic ratios (as an alternative to radioisotopes) to describe for the first time Cu dynamics in a freshwater invertebrate, the bivalve Corbicula fluminea. In the laboratory, Corbicula uptake and loss rate constants were determined from an environmentally realistic waterborne exposure to 65Cu (5.7 ??g L-1). That is, we spiked deionized water with Cu that was 99.4% 65Cu. Net tracer uptake was detectable after 1 day and strongly evident after 4 days. Thus, short-term exposures necessary to determine uptake dynamics are feasible with stable isotopes of Cu. In Corbicula, 65Cu depuration was biphasic. An unusually low rate constant of loss (0.0038 d-1) characterized the slow component of efflux, explaining why Corbicula strongly accumulates copper in nature. We incorporated our estimates of rate constants for dissolved 65Cu uptake and physiological efflux into a bioaccumulation model and showed that dietary exposure to Cu is likely an important bioaccumulation pathway for Corbicula.

  17. From water to land: How an invasive clam may function as a resource pulse to terrestrial invertebrates.

    PubMed

    Novais, Adriana; Souza, Allan T; Ilarri, Martina; Pascoal, Cláudia; Sousa, Ronaldo

    2015-12-15

    Resource pulses are episodes of low frequency, large magnitude and short duration that result in increased resource availability in space and time, with consequences for food web dynamics. Studies assessing the importance of resource pulses by invasive alien species in the interface between terrestrial and aquatic ecosystems are rare, especially those in the direction from water to land. This study assessed the importance of massive die-offs of the Asian clam Corbicula fluminea (Müller, 1774) as a resource pulse to the terrestrial invertebrate community after an extreme climatic event using a manipulative experiment. We used 5 levels of C. fluminea density (0, 100, 500, 1000 and 2000ind·m(-2)), with terrestrial invertebrates being censused 7, 30 and 90days after C. fluminea addition. We also assessed the possible effect of plots position, where plots that delimited the experiment were assigned as edge plots and the remaining as core plots. Clear differences were detected in abundance, biomass, richness and diversity of terrestrial invertebrates depending on the C. fluminea density, time and position. Interestingly, the highest abundance of adult Diptera was observed 7days after C. fluminea addition, whereas that of the other terrestrial invertebrates was on day 30, both with C. fluminea densities higher than 500ind·m(-2) located on the edge of the experimental design. This study highlights the importance of major resource pulses after massive die-offs of invasive bivalves, contributing with remarkable amounts of carrion for adjacent terrestrial systems. Part of this carrion can be consumed directly by a great number of invertebrate species while the remainder can enter the detrital food web. Given the high density and biomass attained by several invasive bivalves worldwide and the predicted increase in the number, intensity and magnitude of extreme climatic events, the ecological importance of this phenomenon should be further investigated. Copyright © 2015

  18. Absence of sterols constrains food quality of cyanobacteria for an invasive freshwater bivalve.

    PubMed

    Basen, Timo; Rothhaupt, Karl-Otto; Martin-Creuzburg, Dominik

    2012-09-01

    The accumulation of cyanobacterial biomass may severely affect the performance of aquatic consumers. Here, we investigated the role of sterols in determining the food quality of cyanobacteria for the invasive clam Corbicula fluminea, which has become a common benthic invertebrate in many freshwater ecosystems throughout the world. In standardized growth experiments, juvenile clams were fed mixtures of different cyanobacteria (Anabaena variabilis, Aphanothece clathrata, Synechococcus elongatus) or sterol-containing eukaryotic algae (Cryptomonas sp., Nannochloropsis limnetica, Scenedesmus obliquus). In addition, the cyanobacterial food was supplemented with different sterols. We provide evidence that somatic growth of C. fluminea on cyanobacterial diets is constrained by the absence of sterols, as indicated by a growth-enhancing effect of sterol supplementation. Thus, our findings contribute to our understanding of the consequences of cyanobacterial mass developments for benthic consumers and highlight the importance of considering sterols as potentially limiting nutrients in aquatic food webs.

  19. Bivalve fouling of nuclear power plant service-water systems. Volume 1. Correlation of bivalve biological characteristics and raw-water system design

    SciTech Connect

    Neitzel, D.A.; Johnson, K.I.; Page, T.L.; Young, J.S.; Daling, P.M.

    1984-12-01

    Fouling of raw-water systems in nuclear power plants in the US can affect the safe operation of a power plant. This report describes correlations between the biology of bivalve organisms and the design and operation of power plants that allow bivalves to enter and reside in nuclear power plants. Discussions are focused on safety-related raw-water systems subject to fouling by the Asiatic clam (Corbicula fluminea), the blue mussel (Mytilus edulis), and the American oyster (Crassostrea virginica). Score sheets to rate fouling potential of power plant systems and components are provided.

  20. Mercury bioaccumulation and biomagnification in Ozark stream ecosystems.

    PubMed

    Schmitt, Christopher J; Stricker, Craig A; Brumbaugh, William G

    2011-11-01

    Crayfish (Orconectes spp.), Asian clam (Corbicula fluminea), northern hog sucker (hog sucker; Hypentelium nigricans), and smallmouth bass (smallmouth; Micropterus dolomieu) from streams in southeastern Missouri (USA) were analyzed for total mercury (HgT) and for stable isotopes of carbon (δ¹³C), nitrogen (δ¹⁵N), and sulfur (δ³⁴S) to discern Hg transfer pathways. HgT concentrations were generally lowest in crayfish (0.005-0.112 μg/g dw) and highest in smallmouth (0.093-4.041 μg/g dw), as was δ¹⁵N. HgT was also lower and δ¹⁵N was higher in all biota from a stream draining a more heavily populated historical lead-zinc mining area than from similar sites with mostly undeveloped forested watersheds. δ¹³C in biota was lowest at spring-influenced sites, reflecting CO₂ inputs and temperature influences, and δ³⁴S increased from south to north in all taxa. However, HgT was not strongly correlated with either δ¹³C or δ³⁴S in biota. Trophic position (TP) computed from crayfish δ¹⁵N was lower in hog suckers (mean=2.8) than in smallmouth (mean=3.2), but not at all sites. HgT, δ¹³C, δ³⁴S, and TP in hog suckers increased with total length (length) at some sites, indicating site-specific ontogenetic diet shifts. Changes with length were less evident in smallmouth. Length-adjusted HgT site means in both species were strongly correlated with HgT in crayfish (r²=0.97, P<0.01), but not with HgT in Corbicula (r²=0.02, P>0.05). ANCOVA and regression models incorporating only TP and, for hog suckers, length, accurately and precisely predicted HgT concentrations in both fish species from all locations. Although low compared to many areas of the USA, HgT (and therefore methylmercury) concentrations in smallmouth and hog suckers are sufficiently high to represent a threat to human health and wildlife. Our data indicate that in Ozark streams, Hg concentrations in crayfish are at least partly determined by their diet, with concentrations in hog

  1. Mercury bioaccumulation and biomagnification in Ozark stream ecosystems

    USGS Publications Warehouse

    Schmitt, Christopher J.; Stricker, Craig A.; Brumbaugh, William G.

    2011-01-01

    Crayfish (Orconectes spp.), Asian clam (Corbicula fluminea), northern hog sucker (hog sucker; Hypentelium nigricans), and smallmouth bass (smallmouth; Micropterus dolomieu) from streams in southeastern Missouri (USA) were analyzed for total mercury (HgT) and for stable isotopes of carbon (δ13C), nitrogen (δ15N), and sulfur (δ34S) to discern Hg transfer pathways. HgT concentrations were generally lowest in crayfish (0.005–0.112 μg/g dw) and highest in smallmouth (0.093–4.041 μg/g dw), as was δ15N. HgT was also lower and δ15N was higher in all biota from a stream draining a more heavily populated historical lead–zinc mining area than from similar sites with mostly undeveloped forested watersheds. δ13C in biota was lowest at spring-influenced sites, reflecting CO2 inputs and temperature influences, and δ34S increased from south to north in all taxa. However, HgT was not strongly correlated with either δ13C or δ34S in biota. Trophic position (TP) computed from crayfish δ15N was lower in hog suckers (mean=2.8) than in smallmouth (mean=3.2), but not at all sites. HgT, δ13C, δ34S, and TP in hog suckers increased with total length (length) at some sites, indicating site-specific ontogenetic diet shifts. Changes with length were less evident in smallmouth. Length-adjusted HgT site means in both species were strongly correlated with HgT in crayfish (r2=0.97, P<0.01), but not with HgT in Corbicula (r2=0.02, P>0.05). ANCOVA and regression models incorporating only TP and, for hog suckers, length, accurately and precisely predicted HgT concentrations in both fish species from all locations. Although low compared to many areas of the USA, HgT (and therefore methylmercury) concentrations in smallmouth and hog suckers are sufficiently high to represent a threat to human health and wildlife. Our data indicate that in Ozark streams, Hg concentrations in crayfish are at least partly determined by their diet, with concentrations in hog suckers, smallmouth, and

  2. Assessment of ametryn contamination in river water, river sediment, and mollusk bivalves in São Paulo state, Brazil.

    PubMed

    Jacomini, Analu Egydio; de Camargo, Plínio Barbosa; Avelar, Wagner Eustáquio Paiva; Bonato, Pierina Sueli

    2011-04-01

    São Paulo state, Brazil, is one of the main areas of sugar cane agriculture in the world. Herbicides, in particular, ametryn, are extensively used in this extensive area, which implies that this herbicide is present in the environment and can contaminate the surface water by running off. Thereby, residues of ametryn were analyzed in samples of river water an river sediment and in freshwater bivalves obtained from the rivers Sapucaí, Pardo and Mogi-Guaçu in São Paulo State, Brazil. Samples were taken in the winter of 2003 and 2004 in two locations in each river. The specimens of freshwater bivalves collected and analyzed were Corbicula fluminea, an exotic species, and Diplodon fontaineanus, a native species. Additionally, the evaluation of the ability of bioconcentration and depuration of ametryn by the freshwater bivalve Corbicula fluminea was also performed. Ametryn concentrations in the samples were measured by liquid chromatography coupled to mass spectrometry. Residues of ametryn in water (50 ng/L) and in freshwater bivalves (2-7 ng/g) were found in the Mogi-Guaçu River in 2004, and residues in river sediments were found in all rivers in 2003 and 2004 (0.5-2 ng/g). The observation of the aquatic environment through the analysis of these matrixes, water, sediment, and bivalves, revealed the importance of the river sediment in the accumulation of the herbicide ametryn, which can contaminate the biota. © Springer Science+Business Media, LLC 2010

  3. Strontium and barium incorporation into freshwater bivalve shells

    NASA Astrophysics Data System (ADS)

    Zhao, Liqiang; Schöne, Bernd R.

    2015-04-01

    Despite strong vital control, trace elements of bivalve shells can potentially serve as proxies of environmental change. However, to reconstruct past environments with the geochemical properties of the shells and determine the degree to which the element levels are biologically influenced, it is essential to experimentally determine the relationship between environmental variables and the element composition of the shells. In particular, the trace element geochemistry of freshwater bivalve shells has so far received little attention. Here, we present a controlled laboratory experiment that aimed at providing a better understanding of the influence of changing environmental variables on the incorporation of trace elements into freshwater bivalve shells. Under controlled conditions, Asian clams Corbicula fluminea were reared for 5 weeks in three sets of experiments: (1) different water temperature (10, 16, and 22° C) and different food levels (an equally mixed Scenedesmu quadricanda and Chlorella vulgaris at rations of 0.4, 2, 4, and 8 × 104 cells ml-1 d-1); (2) different water temperature (10, 16, and 22° C) and different element levels (Sr, Ba); (3) five sediment types (sand, slightly muddy sand, muddy sand, slightly sandy mud and mud). In the first set of experiments, shell Sr/Ca showed a significantly negative correlation with temperature, where Sr/Ca decreased linearly by about 1.6 to 2.1% per 1° C, but responded far more weakly to food availability. On the other hand, temperature and food availability affected shell Ba/Ca ratios, which potentially confounds the interpretation of Ba/Ca variations. Moreover, shell Sr/Ca and Ba/Ca exhibited a clearly negative dependence on shells growth rate that varied significantly among combinations of temperature and food availability. In the second set of experiments, shell Sr/Ca and Ba/Ca were positively and linearly related to water Sr/Ca and Ba/Ca for all temperatures. However, significantly negative effects of

  4. Freshwater clam extract supplementation improves wound healing by decreasing the tumor necrosis factor α level in blood.

    PubMed

    Peng, Yi-Chi; Fwu-LinYang; Subeq, Yi-Maun; Tien, Chin-Chieh; Lee, Ru-Ping

    2017-03-01

    The freshwater clam (Corbicula fluminea) is a widely consumed functional food in Asia and is traditionally used to improve health and either prevent or treat inflammation-related diseases. Numerous studies have proposed that freshwater clams act to prevent and attenuate inflammatory responses, and also serve as a possible inhibitor to systemic inflammation. However, there is limited information available about the effects of freshwater clams on wound healing. The present study investigated the influence of freshwater clam extract (FCE) on wound healing and inflammatory responses in a cutaneous incision model. Sixteen rats were used and divided into two groups: the FCE group and the normal saline (NS) group. The rats underwent dorsal full-thickness skin excisional wounds (diameter 20 × 10 mm). FCE or NS was administered for oral feeding twice daily for 14 days after wounding. Blood samples were taken and analyzed, and wound areas were measured at several time points during the 2 weeks after excision. On day 14 after wounding, skin biopsies from the wound sites were sent for histological examination. Treatment with FCE (71.63 ± 9.51 pg mL(-1) ) decreased tumor necrosis factor-α levels compared to the NS group (109.86 ± 12.55 pg mL(-1) ) after wounding at 3 h (P < 0.05). There were no significant differences in the levels of white blood cells, interleukin (IL)-6, or IL-10. The wound areas of the NS group (23.9%) were larger than those in the FCE group (8.26%) on day 14 (P < 0.05). Numerous fibroblasts and collagen fiber organization were observed in the FCE group. FCE supplementation improves the wound healing process. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  5. Zooplankton variability and larval striped bass foraging: Evaluating potential match/mismatch regulation

    USGS Publications Warehouse

    Chick, J.H.; Van Den Avyle, M.J.

    1999-01-01

    We quantified temporal and spatial variability of zooplankton in three potential nursery sites (river, transition zone, lake) for larval striped bass (Morone saxatilis) in Lake Marion, South Carolina, during April and May 1993-1995. In two of three years, microzooplankton (rotifers and copepod nauplii) density was significantly greater in the lake site than in the river or transition zone. Macrozooplankton (>200 ??m) composition varied among the three sites in all years with adult copepods and cladocerans dominant at the lake, and juvenile Corbicula fluminea dominant at the river and transition zone. Laboratory feeding experiments, simulating both among-site (site treatments) and within-site (density treatments) variability, were conducted in 1995 to quantify the effects of the observed zooplankton variability on foraging success of larval striped bass. A greater proportion of larvae fed in the lake than in the river or transition-zone treatments across all density treatments: mean (x), 10x and 100x. Larvae also ingested significantly more dry mass of prey in the lake treatment in both the mean and 10x density treatments. Field zooplankton and laboratory feeding data suggest that both spatial and temporal variability of zooplankton influence larval striped bass foraging. Prey density levels that supported successful foraging in our feeding experiments occurred in the lake during late April and May in 1994 and 1995 but were never observed in the river or transition zone. Because the rivers flowing into Lake Marion are regulated, it may be possible to devise flow management schemes that facilitate larval transport to the lake and thereby increase the proportion of larvae matched to suitable prey resources.

  6. Predator prey interactions of Procambarus clarkii with aquatic macroinvertebrates in single and multiple prey systems

    NASA Astrophysics Data System (ADS)

    Correia, Alexandra Marçal; Bandeira, Nuno; Anastácio, Pedro Manuel

    2005-11-01

    Understanding the interspecific interactions of Procambarus clarkii with other aquatic macroinvertebrates will help to unveil the mechanisms and processes underlying biological invasiveness. The purpose of this study was to investigate predator-prey interactions of two ontogenic phases of P. clarkii with native and exotic species of aquatic macroinvertebrates at a single and multiple prey level. We performed laboratory experiments to determine the consumption and the behavioral responses of Chironomus riparius, Physa acuta and Corbicula fluminea to P. clarkii. The presence of P. clarkii significantly affected the abundance of C. riparius and P. acuta, but not of C. fluminea whether prey species were provided singly or simultaneously. The consumption of C. riparius by P. clarkii was higher than P. acuta for both crayfish sizes and situations (single/multiple prey systems) and C. fluminea was never consumed. Physa acuta was the only species that exhibited an anti-predator behavior to P. clarkii. Our results show that P. clarkii can have strong consumptive and trait effects on aquatic macroinvertebrate prey at a single and multiple prey level, resulting in differential impacts on different prey species. This study clarifies some aspects of the predator-prey interactions between P. clarkii and native as well as other exotic macroinvertebrate species that have invaded freshwater biocenosis worldwide.

  7. Suspended material availability and filtration-biodeposition processes performed by a native and invasive bivalve species in streams

    USGS Publications Warehouse

    Atkinson, C.L.; First, M.R.; Covich, A.P.; Opsahl, S.P.; Golladay, S.W.

    2011-01-01

    Unionid mussels are among the most threatened group of freshwater organisms globally. They are known for their ability to filter food particles from flowing and standing waters. However, invasive bivalve species, such as the Asian clam (Corbicula fluminea) in North America, have the potential to overlap in feeding and potentially out-compete the native species. Yet, the feeding preferences of unionid mussels and C. fluminea are incompletely understood. We hypothesized that Elliptio crassidens (native) and C. fluminea (invasive) would select for specific organic components present within seston. We examined changes in seston (dry mass and ash-free dry mass) resulting from bivalve feeding activity for three size classes of material that were isolated using gravimetric filtration. The treatments were also sub-sampled for flow cytometry (FC) which separated the suspended materials in the stream water into five categories: detritus, heterotrophic bacteria, picoautotrophs, nanoautotrophs, and heterotrophic nanoeukaryotes. Our results indicated that both species of bivalve showed preferences for organic and living materials. E. crassidens preferentially filtered nanoeukaryotes, whose decreases were associated with an increase in bacteria. In contrast, C. fluminea preferred smaller materials through selective filtration of picoautotrophs. In addition, both species increased the concentration of large materials toward the end of the experiment because of the suspension of their pseudofeces biodeposits. To our knowledge, this study is the first to examine grazing by bivalve species on natural stream particulate matter using FC. Our results suggest that native and non-native mussels have different functional roles, which has important implications for organic matter processing and food webs in streams. ?? 2011 Springer Science+Business Media B.V.

  8. Using biochemical and isotope geochemistry to understand the environmental and public health implications of lead pollution in the lower Guadiana River, Iberia: a freshwater bivalve study.

    PubMed

    Company, R; Serafim, A; Lopes, B; Cravo, A; Shepherd, T J; Pearson, G; Bebianno, M J

    2008-11-01

    Lead is a natural component of aquatic ecosystems with no known biological role and is highly toxic. Its toxicity stems from its ability to mimic biologically important metals and to produce membrane damage through lipid peroxidation (LPO). Most lead poisoning symptoms are thought to occur by interfering with an essential enzyme, delta-aminolevulinic acid dehydratase (ALAD), the activity of which is markedly inhibited by lead. The purpose of this work was to study the levels and effects of lead pollution (responses of ALAD and oxidative stress biomarker LPO) in the freshwater bivalve Corbicula fluminea along the lower Guadiana River (Portugal and Spain); a major river system impacted by historic mining pollution and more recent anthropogenic inputs. The results show that the enzymatic activity of ALAD is negatively correlated with the total Pb concentration of the whole tissue suggesting that ALAD has considerable potential as a biomarker of lead exposure in C. fluminea. To identify the sources of lead to which bivalves have been exposed, high precision (206)Pb/(204)Pb, (207)Pb/(204)Pb, (208)Pb/(204)/Pb ratios for C. fluminea confirm that historical mining activities in the Iberian Pyrite Belt are the dominant source of lead pollution in the lower Guadiana River. The isotope patterns however exhibit marked seasonal and geographic variation in response to rainfall and river water management. Locally, other anthropogenic sources of lead have been detected in C. fluminea close to population centres, thus adding to its versatility as a freshwater bio-indicator. Overall, the study highlights the value of natural ecosystems as monitors of water quality and their importance for public health assessment and surveillance.

  9. Identifying major pesticides affecting bivalve species exposed to agricultural pollution using multi-biomarker and multivariate methods.

    PubMed

    Damásio, Joana; Navarro-Ortega, Alícia; Tauler, Romà; Lacorte, Silvia; Barceló, Damià; Soares, Amadeu M V M; López, Miguel Angel; Riva, Mari Carmen; Barata, Carlos

    2010-08-01

    The aim of this investigation was to identify major pesticides that may cause detrimental effects in bivalve species affected by agricultural pollution. Investigations were carried out using freshwater clams (Corbicula fluminea) transplanted in the main drainage channels that collect the effluents coming from agriculture fields in the Ebro Delta (NE Spain) during the main growing season of rice (from May to August). Environmental hazards were assessed by measuring simultaneous up 46 contaminant levels and 9 biomarker responses. Measured biological responses showed marked differences across sites and months. Antioxidant and esterase enzyme responses were in most cases inhibited. Lipid peroxidation levels increased steadily from May in upstream stations to August in drainage channels. Principal Component (PCA) and Partial Least Squares to Latent Structure regression (PLS) analyses allowed the identification of endosulfan, propanil, and phenylureas as being the chemical contaminants causing the most adverse effects in the studied species.

  10. Occurrence and concentrations of polycyclic aromatic hydrocarbons in semipermeable membrane devices and clams in three urban streams of the Dallas-Fort Worth Metropolitan Area, Texas

    USGS Publications Warehouse

    Moring, J.B.; Rose, D.R.

    1997-01-01

    Semipermeable membrane devices (SPMDs) and Asiatic clams, Corbicula fluminea (MuLLER), were deployed at stream sites in the Dallas-Fort Worth Metropolitan Area to assess the presence of bioavailable, dissolved polycyclic aromatic hydrocarbons (PAHs). Twenty-four PAHs were detected in SPMDs, 20 of which occurred at all sites. Only three PAHs were detected in the co-deployed clams. Throughout all sites, non-alkylated PAHs were found at greater levels in SPMDs than alkylated forms. Nine of 16 Priority Pollutant PAHs were detected in SPMDs. Estimated concentrations of PAHs in water were generally two to three orders of magnitude less than standard minimum analytical reporting levels; however, for bent (a) anthracene, benzo (a) pyrene, and chrysene, estimated concentrations in water exceeded the U.S. Environmental Protection Agency's human health criteria for these carcinogens in water and aquatic organisms.

  11. Effects of cationic surfactant exposure to a bivalve mollusc in stream mesocosms

    SciTech Connect

    Belanger, S.E.; Davidson, D.H.; Cherry, D.S. . Environmental Science Dept.); Farris, J.L.; Reed, D. . Univ. Center for Environmental and Hazardous Materials Studies and Biology Dept.)

    1993-10-01

    Effects of the cationic surfactant lauryl trimethyl ammonium chloride (C[sub 12]-TMAC) on growth, reproduction, cellulolytic enzyme activity, and larval colonization of Asiatic clams (Corbicula fluminea) were investigated in experimental stream mesocosms. Clams from three different populations and of two known morphotypes were evaluated for growth in two 8-week experiments in fall 1989 and spring 1990. Growth was impaired at 185 [mu]g/L. It is not known at this time to what extent the effects on pediveligers would be manifested relative to recruitment to later life stages. These findings were compared to a published safety assessment for mono-alkyl quanternaries, of which TMAC is a member. The findings reported here do not substantially alter conclusions from previous studies; however, clams appear to be among the more sensitive taxa studied thus far.

  12. Effects of millimeter wave carbon fibers on filter-feeding freshwater invertebrates.

    PubMed

    Soucek, David J; Dickinson, Amy; Cropek, Donald M

    2010-05-01

    The purpose of our study was to investigate the sub-lethal effects of millimeter wave carbon fibers (MWCF), a military obscurant, on filter-feeding freshwater invertebrates. We observed decreased survival, reproduction, and oxygen consumption in Daphnia magna at realistic loading rates. In experiments with the Asiatic clam (Corbicula fluminea), soft tissue dry weight and tissue condition index were not significantly different among control and MWCF exposed treatments; however, using a (15)N labeled alga as food, we observed decreased nitrogen turnover in tissues of clams exposed to MWCF, suggesting lower filtering or ingestion rates. Our findings combined with previous demonstrations of MWCF toxicity to green algae suggest that over a period of several months, bivalve growth may be inhibited, and cladoceran populations may be even more strongly affected by MWCF. Given that these fibers are persistent, further experiments should be conducted to determine the longer-term effects of contamination of water bodies with MWCF.

  13. Mercury in freshwater fish and clams from the Cerro Prieto geothermal field of Baja California, Mexico

    SciTech Connect

    Gutierrez-Galindo, E.A.; Munoz, G.F.; Flores, A.A.

    1988-08-01

    Several reports have expressed concern about the potential toxicity hazards and environmental contamination of mercury emissions from geothermal fields in Hawaii, New Zealand, Iceland, California and Mexico. Inorganic mercury discharged from the sources may accumulate in the sediments of rivers or lakes and, after microbiological methylation may become concentrated in the edible tissue of fish. This study involves assessment of geothermal mercury pollution arising from Cerro Prieto. For this purpose the fish Tilapia mossambica and the clam Corbicula fluminea were collected from the freshwater courses of the Mexicali Valley. Reports indicated that in 1982, 13 t of T. mossambica were destinated for human consumption. A further aim was to provide base line data and information relevant to the level of mercury contamination for the Mexicali Valley.

  14. Lead in clams and fish of dietary importance from Coatzacoalcos estuary (Gulf of Mexico), an industrialized tropical region.

    PubMed

    Ruelas-Inzunza, J; Gárate-Viera, Y; Páez-Osuna, F

    2007-11-01

    With the aim of knowing seasonal variability of lead in fish and bivalve species from Coatzacoalcos estuary, biota collected during three seasons was examined. In muscle tissue of fish, the highest level (5.4 microg g(-1)) was found in the longnose gar Lepisosteus osseus from San Francisco stream (a highly impacted site); the lowest value (0.2 microg g(-1)) was registered in yellowfin mojarra Gerres cinereus from Ostión lagoon (control site). In bivalves, concentrations in soft tissue ranged from 1.5 microg g(-1) in Polymesoda caroliniana from Calzadas river, to 0.1 microg g(-1) in Corbicula fluminea from Hidalgotitlán (control site).

  15. Evaluation of Using Caged Clams to Monitor Contaminated Groundwater Exposure in the Near-Shore Environment of the Hanford Site 300 Area

    SciTech Connect

    Larson, Kyle B.; Poston, Ted M.; Tiller, Brett L.

    2008-01-31

    The Asiatic clam (Corbicula fluminea) has been identified as an indicator species for locating and monitoring contaminated groundwater in the Columbia River. Pacific Northwest National Laboratory conducted a field study to explore the use of caged Asiatic clams to monitor contaminated groundwater upwelling in the 300 Area near-shore environment and assess seasonal differences in uranium uptake in relation to seasonal flow regimes of the Columbia River. Additional objectives included examining the potential effects of uranium accumulation on growth, survival, and tissue condition of the clams. This report documents the field conditions and procedures, laboratory procedures, and statistical analyses used in collecting samples and processing the data. Detailed results are presented and illustrated, followed by a discussion comparing uranium concentrations in Asiatic clams collected at the 300 Area and describing the relationship between river discharge, groundwater indicators, and uranium in clams. Growth and survival, histology, and other sources of environmental variation also are discussed.

  16. Mercury bioaccumulation and biomagnification in Ozark stream ecosystems

    USGS Publications Warehouse

    Schmitt, Christopher J.; Stricker, Craig A.; Brumbaugh, William G.

    2011-01-01

    Crayfish (Orconectes spp.), Asian clam (Corbicula fluminea), northern hog sucker (hog sucker; Hypentelium nigricans), and smallmouth bass (smallmouth; Micropterus dolomieu) from streams in southeastern Missouri (USA) were analyzed for total mercury (HgT) and for stable isotopes of carbon (δ13C), nitrogen (δ15N), and sulfur (δ34S) to discern Hg transfer pathways. HgT concentrations were generally lowest in crayfish (0.005-0.112 μg/g dw) and highest in smallmouth (0.093-4.041 μg/g dw), as was δ15N. HgT was also lower and δ15N was higher in all biota from a stream draining a more heavily populated historical lead-zinc mining area than from similar sites with mostly undeveloped forested watersheds. δ13C in biota was lowest at spring-influenced sites, reflecting CO2 inputs and temperature influences, and δ34S increased from south to north in all taxa. However, HgT was not strongly correlated with either δ13C or δ34S in biota. Trophic position (TP) computed from crayfish δ15N was lower in hog suckers (mean=2.8) than in smallmouth (mean=3.2), but not at all sites. HgT, δ13C, δ34S, and TP in hog suckers increased with total length (length) at some sites, indicating site-specific ontogenetic diet shifts. Changes with length were less evident in smallmouth. Length-adjusted HgT site means in both species were strongly correlated with HgT in crayfish (r2=0.97, Pr2=0.02, P>0.05). NCOVA and regression models incorporating only TP and, for hog suckers, length, accurately and precisely predicted HgT concentrations in both fish species from all locations. Although low compared to many areas of the USA, HgT (and therefore methylmercury) concentrations in smallmouth and hog suckers are sufficiently high to represent a threat to human health and wildlife. Our data indicate that in Ozark streams, Hg concentrations in crayfish are at least partly determined by their diet, with concentrations in hog suckers, smallmouth, and possibly other higher-level consumers largely

  17. Mercury bioaccumulation and biomagnification in Ozarkstream ecosystems

    USGS Publications Warehouse

    Schmitt, C.J.; Stricker, C.A.; Brumbaugh, W.G.

    2011-01-01

    Crayfish (Orconectes spp.), Asian clam (Corbicula fluminea), northern hog sucker (hog sucker; Hypentelium nigricans), and smallmouth bass (smallmouth; Micropterus dolomieu) from streams in southeastern Missouri (USA) were analyzed for total mercury (HgT) and for stable isotopes of carbon (δ¹³C), nitrogen (δ¹⁵N), and sulfur (δ³⁴S) to discern Hg transfer pathways. HgT concentrations were generally lowest in crayfish (0.005-0.112 μg/g dw) and highest in smallmouth (0.093-4.041 μg/g dw), as was δ¹⁵N. HgT was also lower and δ¹⁵N was higher in all biota from a stream draining a more heavily populated historical lead-zinc mining area than from similar sites with mostly undeveloped forested watersheds. δ¹³C in biota was lowest at spring-influenced sites, reflecting CO₂ inputs and temperature influences, and δ³⁴S increased from south to north in all taxa. However, HgT was not strongly correlated with either δ¹³C or δ³⁴S in biota. Trophic position (TP) computed from crayfish δ¹⁵N was lower in hog suckers (mean=2.8) than in smallmouth (mean=3.2), but not at all sites. HgT, δ¹³C, δ³⁴,/sup>S, and TP in hog suckers increased with total length (length) at some sites, indicating site-specific ontogenetic diet shifts. Changes with length were less evident in smallmouth. Length-adjusted HgT site means in both species were strongly correlated with HgT in crayfish (r²=0.97, P²=0.02, P>0.05). ANCOVA and regression models incorporating only TP and, for hog suckers, length, accurately and precisely predicted HgT concentrations in both fish species from all locations. Although low compared to many areas of the USA, HgT (and therefore methylmercury) concentrations in smallmouth and hog suckers are sufficiently high to represent a threat to human health and wildlife. Our data indicate that in Ozark streams, Hg concentrations in crayfish are at least partly determined by their diet, with concentrations in hog suckers, smallmouth, and possibly

  18. An Early Instance of Upper Palaeolithic Personal Ornamentation from China: The Freshwater Shell Bead from Shuidonggou 2

    PubMed Central

    Wei, Yi; d’Errico, Francesco; Vanhaeren, Marian; Li, Feng; Gao, Xing

    2016-01-01

    We report the discovery and present a detailed analysis of a freshwater bivalve from Shuidonggou Locality 2, layer CL3. This layer is located c. 40 cm below layer CL2, which has yielded numerous ostrich eggshell beads. The shell is identified as the valve of a Corbicula fluminea. Data on the occurrence of this species in the Shuidonggou region during Marine Isotope Stage 3 and taphonomic analysis, conducted in the framework of this study, of a modern biocoenosis and thanatocoenosis suggest that the archeological specimen was collected at one of the numerous fossil or sub-fossil outcrops where valves of this species were available at the time of occupation of level CL3. Experimental grinding and microscopic analysis of modern shells of the same species indicate that the Shuidonggou shell was most probably ground on coarse sandstone to open a hole on its umbo, attach a thread, and use the valve as a personal ornament. Experimental engraving of freshwater shells and microscopic analysis identify an incision crossing the archaeological valve outer surface as possible deliberate engraving. Reappraisal of the site chronology in the light of available radiocarbon evidence suggests an age of at least 34–33 cal kyr BP for layer CL3. Such estimate makes the C. fluminea recovered from CL3 one of the earliest instances of personal ornamentation and the earliest example of a shell bead from China. PMID:27227330

  19. An Early Instance of Upper Palaeolithic Personal Ornamentation from China: The Freshwater Shell Bead from Shuidonggou 2.

    PubMed

    Wei, Yi; d'Errico, Francesco; Vanhaeren, Marian; Li, Feng; Gao, Xing

    2016-01-01

    We report the discovery and present a detailed analysis of a freshwater bivalve from Shuidonggou Locality 2, layer CL3. This layer is located c. 40 cm below layer CL2, which has yielded numerous ostrich eggshell beads. The shell is identified as the valve of a Corbicula fluminea. Data on the occurrence of this species in the Shuidonggou region during Marine Isotope Stage 3 and taphonomic analysis, conducted in the framework of this study, of a modern biocoenosis and thanatocoenosis suggest that the archeological specimen was collected at one of the numerous fossil or sub-fossil outcrops where valves of this species were available at the time of occupation of level CL3. Experimental grinding and microscopic analysis of modern shells of the same species indicate that the Shuidonggou shell was most probably ground on coarse sandstone to open a hole on its umbo, attach a thread, and use the valve as a personal ornament. Experimental engraving of freshwater shells and microscopic analysis identify an incision crossing the archaeological valve outer surface as possible deliberate engraving. Reappraisal of the site chronology in the light of available radiocarbon evidence suggests an age of at least 34-33 cal kyr BP for layer CL3. Such estimate makes the C. fluminea recovered from CL3 one of the earliest instances of personal ornamentation and the earliest example of a shell bead from China.

  20. Spatial and taxonomic variation in trace element bioaccumulation in two herbivores from a coal combustion waste contaminated stream.

    PubMed

    Fletcher, Dean E; Lindell, Angela H; Stillings, Garrett K; Mills, Gary L; Blas, Susan A; Vaun McArthur, J

    2014-03-01

    Dissimilarities in habitat use, feeding habits, life histories, and physiology can result in syntopic aquatic taxa of similar trophic position bioaccumulating trace elements in vastly different patterns. We compared bioaccumulation in a clam, Corbicula fluminea and mayfly nymph Maccaffertium modestum from a coal combustion waste contaminated stream. Collection sites differed in distance to contaminant sources, incision, floodplain activity, and sources of flood event water and organic matter. Contaminants variably accumulated in both sediment and biofilm. Bioaccumulation differed between species and sites with C. fluminea accumulating higher concentrations of Hg, Cs, Sr, Se, As, Be, and Cu, but M. modestum higher Pb and V. Stable isotope analyses suggested both spatial and taxonomic differences in resource use with greater variability and overlap between species in the more physically disturbed site. The complex but essential interactions between organismal biology, divergence in resource use, and bioaccumulation as related to stream habitat requires further studies essential to understand impacts of metal pollution on stream systems. Copyright © 2014 Elsevier Inc. All rights reserved.

  1. Indirect Selection for Antibiotic Resistance in Multiple Stream Microhabitats

    NASA Astrophysics Data System (ADS)

    Wright, M. S.; Peltier, G. L.; McArthur, J.

    2005-05-01

    One aspect challenging public health efforts to minimize the spread of antibiotic resistance (AR) is the prevalence of resistant bacteria in the environment. Anthropogenic-derived sources of selection are typically implicated as mechanisms for maintaining AR in the environment. Here we report an additional mechanism for maintaining AR in the environment through co- or cross-resistance to heavy metals. Using culture-independent techniques, bacteria isolated from heavy-metal contaminated sites were more tolerant of antibiotics and metals compared to those bacteria from a reference site. This evidence supports our hypothesis that metal contamination directly selects for metal tolerant bacteria while indirectly selecting for antibiotic tolerant bacteria. Additionally, to assess how antibiotic- and metal-tolerance may be transported through a stream network, we studied antibiotic and metal-tolerance patterns over four months in bacteria collected from multiple stream microhabitats including water column, biofilm, sediment, and Corbicula fluminea (Asiatic clam) digestive tracts. Sediment bacteria were the most tolerant to antibiotics and metals, while bacteria from Corbicula were the least tolerant. Differences between these microhabitats may be important for predicting antibiotic resistance transfer and transport in stream environments. Further, temporal dynamics suggest that tolerance patterns within microhabitats are linked to physico-chemical characteristics of the stream.

  2. Phytoplankton dynamics of the fresh, tidal Potomac River, Maryland, for the summers of 1979 to 1981

    USGS Publications Warehouse

    Cohen, Ronald R.H.

    1988-01-01

    The distribution and abundance of phytoplankton in the fresh, tidal Potomac River, Md., was different during 1979-81 from that observed in the 1960's and 1970's. Concentrations of phytoplankton in the 1960's and 1970's reached maximum attainable levels that were limited only by self-shading. A sag in phytoplankton abundance, apparent during the summers of 1980 and 1981 between Rosier Bluff and Marshall Hall, appears to have been caused by the Asiatic clam, Corbicula fluminea. Reduced abundance of phytoplankton throughout the entire fresh, tidal river during the summers of 1980 and 1981 may have been due to grazing by Corbicula, high discharge, and perhaps phosphorus limitation in late August at and downstream of Hallowing Point. Phytoplankton growth rates and chlorophyll-to-cell ratios were highest at Hatton Point and Marshall Hall (the sag reach). A model was constructed that predicted phytoplankton growth rates by varying only chlorophyll a concentration and light penetration. Nutrient concentrations were not required to make the model fit the data. Primary productivity was highest for the year during August 1980 and August 1981. Productivity-per-unit chlorophyll was highest at Hatton Point, where reduced concentrations of phytoplankton permitted the deepest light penetration in the fresh, tidal river.

  3. Bacterial tolerances to metals and antibiotics in metal-contaminated and reference streams.

    PubMed

    Wright, Meredith S; Loeffler Peltier, Gretchen; Stepanauskas, Ramunas; McArthur, J Vaun

    2006-11-01

    Anthropogenic-derived sources of selection are typically implicated as mechanisms for maintaining antibiotic resistance in the environment. Here we report an additional mechanism for maintaining antibiotic resistance in the environment through bacterial exposure to metals. Using a culture-independent approach, bacteria sampled along a gradient of metal contamination were more tolerant of antibiotics and metals compared to bacteria from a reference site. This evidence supports the hypothesis that metal contamination directly selects for metal tolerant bacteria while co-selecting for antibiotic tolerant bacteria. Additionally, to assess how antibiotic and metal tolerance may be transported through a stream network, we studied antibiotic and metal tolerance patterns over three months in bacteria collected from multiple stream microhabitats including the water column, biofilm, sediment and Corbicula fluminea (Asiatic clam) digestive tracts. Sediment bacteria were the most tolerant to antibiotics and metals, while bacteria from Corbicula were the least tolerant. Differences between microhabitats may be important for identifying reservoirs of resistance and for predicting how these genes are transferred and transported in metal-contaminated streams. Temporal dynamics were not directly correlated to a suite of physicochemical parameters, suggesting that tolerance patterns within microhabitats are linked to a complex interaction of the physicochemical characteristics of the stream.

  4. A malacological survey in the Manso Power Plant, State of Mato Grosso, Brazil: new records of freshwater snails, including transmitters of schistosomiasis and exotic species.

    PubMed

    Fernandez, Monica Ammon; Mattos, Aline Carvalho de; Silva, Elizangela Feitosa da; Santos, Sonia Barbosa Dos; Thiengo, Silvana Carvalho

    2014-07-01

    Schistosomiasis is a parasitic disease of public health concern in Brazil, and the construction of hydroelectric dams, in addition to increasing permanent human settlement and tourism, has created conditions suitable for the establishment of mollusks that can transmit schistosomiasis. Such areas require a number of actions to prevent the establishment of schistosomiasis. This paper reports on a freshwater malacological survey carried out in the geographical area of the Manso Power Plant. Mollusks were collected in 18 municipalities in the State of Mato Grosso between February 2002 and February 2004 (qualitative study) and from April 2009 to February 2011 (quantitative study). Thirty-one species of mollusks were collected, including newly recorded species (Antillorbis nordestensis and Burnupia ingae). In addition, the geographic distributions of known species, including Biomphalaria straminea, a snail vector of Schistosoma mansoni, were expanded. A total of 4,507 specimens were collected in the APM Manso reservoir (Usina Hidrelétrica de Aproveitamento Múltiplo de Manso) during the quantitative study, and Biomphalaria amazonica was found in six of the 10 localities analyzed. The Afroasiatic species Melanoides tuberculata, introduced after February 2009, was the dominant species (relative abundance 94.96%). The study area is epidemiologically important due to the occurrence of B. straminea and B. amazonica, which are vectors of schistosomiasis, and M. tuberculata, a snail host of Centrocestus formosanus, which is responsible for centrocestiasis transmission. Observations of M. tuberculata and the exotic freshwater clams Corbicula fluminea and Corbicula largillierti raise concerns about biodiversity.

  5. Occurrence and accumulation of pesticides and organic contaminants in river sediment, water and clam tissues from the San Joaquin River and tributaries, California

    USGS Publications Warehouse

    Pereira, W.E.; Domagalski, J.L.; Hostettler, F.D.; Brown, L.R.; Rapp, J.B.

    1996-01-01

    A study was conducted in 1992 to assess the effects of anthropogenic activities and land use on the water quality of the San Joaquin River and its major tributaries. This study focused on pesticides and organic contaminants, looking at distributions of contaminants in water, bed and suspended sediment, and the bivalve Corbicula fluminea. Results indicated that this river system is affected by agricultural practices and urban runoff. Sediments from Dry Creek contained elevated concentrations of polycyclic aromatic hydrocarbons (PAHs), possibly derived from urban runoff from the city of Modesto; suspended sediments contained elevated amounts of chlordane. Trace levels of triazine herbicides atrazine and simazine were present in water at most sites. Sediments, water, and bivalves from Orestimba Creek, a westside tributary draining agricultural areas, contained the greatest levels of DDT (1,1,1-trichloro-2-2-bis[p-chlorophenyl]ethane), and its degradates DDD (1,1-dichloro-2,2-bis[p-chlorophenyl]ethane), and DDE (1,1-dichloro-2,2- bis[p-chlorophenyl]ethylene). Sediment adsorption co efficients (K(oc)), and bioconcentration factors (BCF) in Corbicula of DDT, DDD, and DDE at Orestimba Creek were greater than predicted values. Streams of the western San Joaquin Valley can potentially transport significant amounts of chlorinated pesticides to the San Joaquin River, the delta, and San Francisco Bay. Organochlorine compounds accumulate in bivalves and sediment and may pose a problem to other biotic species in this watershed.

  6. Dynamics and control of the Asiatic clam in the New River, Virginia. Research report

    SciTech Connect

    Cherry, D.S.; Rodgers, J.H. Jr.; Graney, R.L.; Cairns, J. Jr.

    1980-01-01

    The Asiatic clam, Corbicula fluminea, has invaded the New River at the rate of 9 miles a year from the Kanawha River, which enters downstream from the Glen Lyn coal-powered generating plant in Virginia. During the period of investigation, October 1976-September 1978, clams were more numerous in the vicinity of the thermal discharge of the plant than they were in unheated waters, and their population fell sharply during the winter months, when the water temperature dropped to approximately 2C. The temperature (35C) of the heated discharge water in late summer did not adversely affect the clam. High mortality occurred at temperatures greater or equal to 36C in laboratory thermal tolerance studies. The clam proved to be highly resistant to the conventional biocidal practice of intermittent chlorination and to exposure to heavy metals in both static and artificial stream bioassays. Copper was more toxic than either zinc or a combination of zinc and copper. Potassium was not an effective biocidal agent at low concentrations (less than 100 mg/l). Measurements of 42 elements in water, sediment, clam shell, and visceral tissue revealed that Corbicula was an efficient accumulator of many elements.

  7. Stress detection in bivalve mollusk using non-invasive bioelectric monitoring of myoneural behavior

    SciTech Connect

    Morgan, E.L.; Hardison, B.S.; Dawson, V.K.; Waller, D.; Waller, W.T.; Dickson, K.L.; Allen, H.J.

    1995-12-31

    Few studies have demonstrated cause-and-effect linkages between extrinsic environmental factors and intrinsic bioelectric action potentials of bivalve mollusk using non-invasive, non-destructive approaches. A non-invasive, external probe configuration and detection system, similar to one used previously with native unionids, was developed for continuously monitoring bioelectric activities of clams and mussels. Using remote probes and differential amplifiers, bioelectric activities were recorded for cardiac, adductor, siphon and foot responses using a computer equipped with integrating software. To test if remote, non-invasive probes would detect similar information to that recorded by invasive needle electrodes, two individuals of zebra mussel (Dreissenia polymorpha), and Asiatic clam (Corbicula fluminea) were each configured with two sets of probes. One set was inserted between the valves and along the inside surface of the shelf; the other set was positioned remotely about the outside margins of the valves. Signal validation was made by simultaneously recording bioelectric responses for the same animal from both sets of probes. In preliminary stress tests monitored bivalves were subjected to changes in temperatures over 2 to 3 hr intervals from ambient to potentially lethal levels (20 to 30 C for zebra, 25 C to 40 C for corbicula). Dramatic increases resulted in both number and amplitude of cardiac events as temperature increased. Planned studies will use this approach to evaluate bivalve myoneural behavior patterns in response to chemical and non-chemical stimuli.

  8. Field Validation of Toxicity Tests to Evaluate the Potential for Beneficial Use of Produced Water

    SciTech Connect

    Joseph Bidwell; Jonathan Fisher; Naomi Cooper

    2008-03-31

    This study investigated potential biological effects of produced water contamination derived from occasional surface overflow and possible subsurface intrusion at an oil production site along the shore of Skiatook Lake, Oklahoma. We monitored basic chemistry and acute toxicity to a suite of standard aquatic test species (fathead minnow-Pimephales promelas, Daphnia pulex, Daphnia magna, and Ceriodaphnia dubia) in produced water and in samples taken from shallow groundwater wells on the site. Toxicity identification evaluations and ion toxicity modeling were used to identify toxic constituents in the samples. Lake sediment at the oil production site and at a reference site were also analyzed for brine intrusion chemically and by testing sediment toxicity using the benthic invertebrates, Chironomus dilutus, and Hyallela azteca. Sediment quality was also assessed with in situ survival and growth studies with H. azteca and the Asian clam, Corbicula fluminea, and by benthic macroinvertebrate community sampling. The produced water was acutely toxic to the aquatic test organisms at concentrations ranging from 1% to 10% of the whole produced water sample. Toxicity identification evaluation and ion toxicity modeling indicated major ion salts and hydrocarbons were the primary mixture toxicants. The standardized test species used in the laboratory bioassays exhibited differences in sensitivity to these two general classes of contaminants, which underscores the importance of using multiple species when evaluating produced water toxicity. Toxicity of groundwater was greater in samples from wells near a produced water injection well and an evaporation pond. Principle component analyses (PCA) of chemical data derived from the groundwater wells indicated dilution by lake water and possible biogeochemical reactions as factors that ameliorated groundwater toxicity. Elevated concentrations of major ions were found in pore water from lake sediments, but toxicity from these ions was

  9. Residual effects of lead and zinc mining on freshwater mussels in the Spring River Basin (Kansas, Missouri, and Oklahoma, USA).

    PubMed

    Angelo, Robert T; Cringan, M Steve; Chamberlain, Diana L; Stahl, Anthony J; Haslouer, Stephen G; Goodrich, Clint A

    2007-10-01

    Concentrations of selected trace elements in surface water and fluvial sediment were investigated as possible factors limiting the distribution and abundance of freshwater mussels in the Spring River Basin, a 6600 km(2) watershed overlapping a former Pb and Zn mining and ore processing district in the central USA. Mussel taxa richness surveys and supporting physical habitat assessments were performed in 23 stream reaches dispersed throughout the basin and above and below former mining sites. Quantitative mussel density surveys were performed in the Spring River at one upstream reference location and one downstream location. Concentrations of 16 trace elements in the soft tissues of mussels and Asian clams (Corbicula fluminea) were determined at most survey sites. Comparable analyses were performed on surface water samples collected during base flow and peak flow synoptic surveys and sediment samples collected during base flow periods. Sites on the Spring River immediately upstream of heavily mined areas supported at least 21-25 species of mussels, whereas sites near the lower terminus of the river yielded evidence of 6-8 extant species. Between the upper and lower quantitative survey sites, mean mussel and clam densities declined by 89% and 97%, respectively. Tributary reaches below heavily mined areas lacked evident bivalve communities and contained concentrations of Cd, Pb, and Zn that continually or sporadically exceeded hardness-dependent water quality criteria and consensus-based sediment quality guidelines (probable effect concentrations). In less contaminated stream reaches supporting bivalves, concentrations of Cd, Pb, and Zn in mussels and clams were correlated spatially with the levels occurring in surficial sediment (0.50 < or = tau < or = 0.64, p < or = 0.03). In non-headwater perennial stream reaches, sediment Cd, Pb, and Zn levels were related inversely to mussel taxa richness (-0.80 < or = tau < or = -0.64, p < or = 0.004). Metal contaminant burdens

  10. Selenium accumulation in benthic bivalves and fine sediments of San Francisco Bay, the Sacramento-San Joaquin Delta, and selected tributaries

    USGS Publications Warehouse

    Johns, Carolyn; Luoma, Samuel N.; Elrod, Virginia

    1988-01-01

    Spatial distributions of selenium were determined in fine-grained, oxidized, surface sediments and in two benthic bivalves (Corbicula sp., a suspension-feeding freshwater clam, and Macoma balthica, a deposit-feeding brackish-water clam) within San Francisco Bay, the San Joaquin River and three river systems unlikely to be subject to selenium inputs. Biologically available selenium enters the middle reaches of the San Joaquin River from agricultural runoff. However, selenium concentrations in sediments and Corbicula in the lower San Joaquin, upstream from San Francisco Bay, were not significantly different from concentrations in rivers with no known selenium inputs. Biologically available selenium did not appear to enter the northernmost reach of San Francisco Bay from the San Joaquin River in levels which could measurably influence bioaccumulation by Corbicula. Selenium concentrations in Corbicula were enriched in the northernmost reach of San Francisco Bay compared with the rivers, but several lines of evidence suggested that local inputs (perhaps from urban/industrial waste discharges) were the most important sources. Selenium concentrations in Macoma balthica were also elevated at one station in the northern reach of the Bay and at one station in the extreme South Bay. However, no enrichment was evident at two other stations, suggesting a lack of bay-wide contamination. No significant correlation between selenium and mercury concentrations in Corbicula tissues was observed.

  11. Assessing arsenic bioavailability through the use of bioassays

    NASA Astrophysics Data System (ADS)

    Diesel, E.; Nadimpalli, M.; Hull, M.; Schreiber, M. E.; Vikesland, P.

    2009-12-01

    Various methods have been used to characterize the bioavailability of a contaminant, including chemical extractions from soils, toxicity tests, bioaccumulation measurements, estimation from soil properties, in vitro/in vivo tests, and microbial biossays. Unfortunately, these tests are all unique (i.e. they measure bioavailability through different mechanisms) and it is difficult to compare measurements collected using one method to those collected from another. Additionally, there are fundamental aspects of bioavailability research that require further study. In particular, changes in bioavailability over time are not well understood, as well as what the geochemical controls are on changes in bioavailability. In addition, there are no studies aimed at the integration of bioavailability measurements and potential geochemical controls. This research project seeks to find a standard set of assays and sensors that can be used to assess arsenic bioavailability at any field site, as well as to use these tools and techniques to better understand changes in, and controls on, arsenic bioavailability. The bioassays to be utilized in this research are a bioluminescent E. coli assay and a Corbicula fluminea (Asian clam) assay. Preliminary experiments to determine the suitability of the E. coli and C. fluminea assays have been completed. The E. coli assay can be utilized to analyze As(III) and As(V) with a linear standard curve between 5 and 200 ppb for As(III) and 100 ppb and 5 ppm for As(V); no bioluminescent response above background was elicited in the presence of Roxarsone, an organoarsenical. The C. fluminea assay is capable of bioaccumulating As(III), As(V), Roxarsone, and MSMA, with As(III) being the most readily accumulated, followed by As(V), Roxarsone and MSMA, respectively. Additional research will include assessing bioavailability of various arsenic species adsorbed to natural colloidal materials (i.e. clays, iron oxides, NOM) to the E. coli and C. fluminea assays

  12. The Peer Influence Process.

    ERIC Educational Resources Information Center

    Hallinan, Maureen T.

    1981-01-01

    Outlining a conceptual scheme specifying how peer influences mediate the effects of organizational characteristics of schools on student outcomes, with social psychological theories of interpersonal attraction and influence as the basis for the outline, is the aim of this paper. Selection of peers and influence of peers is outlined. (CE)

  13. Peer Influence and Recovery

    ERIC Educational Resources Information Center

    Collier, Crystal; Simpson, Shelly; Najera, John; Weiner, Lauren

    2012-01-01

    Research has shown that peer influence can be negative, by increasing the likelihood that a youth will engage in high-risk behaviors and make risky decisions. However, peer influence can also be positive and protect a youth from these same high-risk activities. This article examines the extent of peer influence and then describes the Alternative…

  14. Peer Influence and Recovery

    ERIC Educational Resources Information Center

    Collier, Crystal; Simpson, Shelly; Najera, John; Weiner, Lauren

    2012-01-01

    Research has shown that peer influence can be negative, by increasing the likelihood that a youth will engage in high-risk behaviors and make risky decisions. However, peer influence can also be positive and protect a youth from these same high-risk activities. This article examines the extent of peer influence and then describes the Alternative…

  15. Improving Influence Operations by Defining Influence and Influence Operations

    DTIC Science & Technology

    2013-12-10

    given behavior .” Martin Fishbein and Icek Ajzen , Belief, Attitude, Intention, and Behavior : an Introduction to Theory and Research (Reading, Mass...deliberately planned and synchronized series of actions designed to produce desired behaviors within adversaries and affected populations through the...They are deliberately intended and planned to influence behavior , as opposed to achieving a purely military objective, such as the destruction of

  16. Influence Operations in Afghanistan

    DTIC Science & Technology

    2006-10-06

    strong central government and marginalizing the influence of radical religious groups who either engage in or support attacks on central government...decision makers are, who they trust, how resolute or tenacious a group is and how open to change a group is. Any Influence Operation must take these...as well as how each group perceives and interacts with other groups is pertinent to developing an effective Influence Operations plan. Pashtun

  17. Derivation of predicted no effect concentrations (PNEC) for 2,4,6-trichlorophenol based on Chinese resident species.

    PubMed

    Jin, Xiaowei; Zha, Jinmiao; Xu, Yiping; Giesy, John P; Richardson, Kristine L; Wang, Zijian

    2012-01-01

    2,4,6-Trichlorophenol (2,4,6-TCP) is a common chemical intermediate and a by-product of water chlorination and combustion processes, and is a priority pollutant of the aquatic environment in many countries. Although information on the toxicity of 2,4,6-TCP is available, there is a lack of information on the predicted no-effect concentration (PNEC) of 2,4,6-TCP, mainly due to the shortage of chronic and site-specific toxicity data. In the present study, acute and sub-chronic toxicity of 2,4,6-TCP on six different resident Chinese aquatic species were determined. PNEC values were calculated and compared by use of two approaches: assessment factor (AF) and species sensitivity distribution (SSD). Values for acute toxicity ranged from 1.1 mg L(-1) (Plagiognathops microlepis) to 42 mg L(-1) (Corbicula fluminea) and the sub-chronic no observed effect concentrations (NOECs) ranged from 0.05 mg L(-1) (Mylopharyngodon piceus) to 2.0 mg L(-1) (C. fluminea). PNECs obtained by the assessment factor approach with acute (AF=1000, 0.001 mg L(-1)) or chronic (AF=10, 0.005 mg L(-1)) toxicity data were one order of magnitude less than those from SSD methods (0.057 mg L(-1)). PNEC values calculated using SSD methods with a 50% certainty for 2,4,6-TCP was less than those obtained by use of the USEPA recommend final chronic value (FCV) method (0.097 mg L(-1)) and the one obtained by use of the USEPA recommend acute-to-chronic (ACR) methods (0.073 mg L(-1)). PNECs derived using AF methods were more protective and conservative than that derived using SSD methods.

  18. Occurrence, distribution and bioaccumulation of endocrine disrupting compounds in water, sediment and biota samples from a European river basin.

    PubMed

    Salgueiro-González, N; Turnes-Carou, I; Besada, V; Muniategui-Lorenzo, S; López-Mahía, P; Prada-Rodríguez, D

    2015-10-01

    The occurrence, distribution and bioaccumulation of five endocrine disrupting compounds (4-tert-octylphenol, 4-n-octylphenol, 4-n-nonylphenol, nonylphenol and bisphenol A) in water, sediment and biota (Corbicula fluminea) collected along the Minho River estuary (NW Iberian Peninsula) were examined. Samples were collected in two campaigns (May and November, 2012) and analyzed by different extraction procedures followed by liquid chromatography tandem mass spectrometry determination. The presence of linear isomers (4-n-octylphenol and 4-n-nonylphenol) was scarcely observed whereas branched isomers (4-tert-octylphenol and nonylphenol) were measured in almost all samples. Wastewater treatment plant effluents and nautical, fishing and agricultural activities are considered the primary source of pollution of the river by alkylphenols. The presence of bisphenol A in the river could be mainly associated to punctual sources of contamination from industrial discharges. A decrease in the total concentration of phenolic compounds in water was observed from spring to autumn (from 0.888 μg L(-1) in May to 0.05 μg L(-1) in November), while similar values were shown in C. fluminea samples from the two campaigns (1388 and 1228 ng g(-1) dw in spring and autumn, respectively). In sediments, the total concentration of the target compounds varied between 13 and 4536 ng g(-1) dw (average of 1041 ng g(-1) dw). Sediment-water partition coefficient (Kd), bioaccumulation factor (BAF) and biota-sediment accumulation factor (BSAF) were estimated and highest values were obtained for nonylphenol. Calculated risk quotients showed low and moderate risk for the aquatic environment from the presence of the target compounds at all sampling points. The estimation of the daily intake of the studied compounds via water and biota ingestion indicated no risk for human health. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Age-Related Changes in Antioxidant and Glutathione S-Transferase Enzyme Activities in the Asian Clam.

    PubMed

    Vranković, J

    2016-03-01

    Aging is accompanied by increased production of free oxygen radicals and impairment of normal cellular functions. The aim of this work was to provide preliminary data on age-related differences in the activities of antioxidant enzymes and phase II biotransformation enzyme glutathione S-transferase (GST) in a wild population of the Asian clam Corbicula fluminea. The antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), glutathione reductase (GR), and GST were assessed in visceral mass of four age classes (0+-, 1+-, 2+-, and 3+-year-old) of C. fluminea clams. Age-related changes were seen in antioxidant enzyme status: levels of total SOD (totSOD) (P < 0.05), MnSOD, and CuZnSOD (P < 0.05) activities increased progressively during aging from younger to older clams. Changes in CAT and GR activities with advancing age were found, the levels being the highest in age class II, then being lower in age classes III and IV (P < 0.05). Activities of GPX and GST were lower in the senescent individuals (2+- and 3+-year-old clams) compared with young individuals (0+- and 1+-year-old clams). Overall, the decline of glutathione-dependent enzyme activities, coupled with higher and lower activities of totSOD and CAT, respectively, as the individual grows older, may render the older animals more susceptible to oxidative stress. Data reported here are not intended to be exhaustive since they concern only age/size structure of the population at one locality, so more detailed studies on both the developmental stages and levels of antioxidant enzymes of this new alien species in Serbian rivers are required.

  20. Are native naiads more tolerant to pollution than exotic freshwater bivalve species? An hypothesis tested using physiological responses of three species transplanted to mercury contaminated sites in the Ebro River (NE, Spain).

    PubMed

    Faria, Melissa; López, Miguel Angel; Díez, Sergi; Barata, Carlos

    2010-11-01

    In the lower Ebro River exist the paradoxical convergence of relatively well preserved river dynamics with the historical presence of a chloralkali plant with a long history of mercury discharges and the recent invasion of foreign bivalves species. Here we performed a comparative study on two alien bivalves, the Zebra mussel and the Asian clam (Dreissena polymorpha and Corbicula fluminea), and one protected species of naiads (Psilunio littoralis), which is the most common species of the freshwater mussel assemblages in this river. Individuals of the three species were transplanted to three sites that included a clean unpolluted upstream site, a contaminated location next to the mercury source and a downstream one. The study focused on digestive gland antioxidant and oxidative stress responses such as antioxidant enzymes, glutathione S transferase, glutathione levels, metallothionein proteins, DNA strand breaks and lipid peroxidation levels. Results evidenced interspecies differences on accumulation levels of mercury, antioxidant defensive systems and oxidative tissue damage. The naiad species, despite of accumulating more mercury showed the greatest antioxidant defensive potential, which was characterized by having high constitutive activities of glutathione S transferase and inducible activities and levels of key antioxidant enzymes and glutathione. Exposed individuals of C. fluminea had moderate levels of metal accumulation, the highest activities of antioxidant enzymes but also high levels of lipid peroxidation. D. polymorpha mussels showed the lowest levels of mercury but the lowest antioxidant responses and consequently the highest levels of oxidative injuries in the DNA and of mortality. Our results support the hypothesis that naiad species might be more tolerant to pollution than exotic species.

  1. Integrative assessment of sediment quality in lower basin affected by former mining in Brazil.

    PubMed

    Bonnail, Estefanía; Buruaem, Lucas M; Morais, Lucas G; Araujo, Giuliana S; Abessa, Denis M S; Sarmiento, Aguasanta M; Ángel DelValls, T

    2017-06-13

    The Ribeira de Iguape River (Southeast Brazil) is metal contaminated by mining activities. Despite it has been cataloged as "in via of restoration" by the literature, this basin is still a sink of pollution in some segments of the fluvial system. This study aimed to assess the sediment quality in the lower part of the RIR basin. The employed approach was based on biological responses of the freshwater clam Corbicula fluminea after 7-day exposure bioassays using as the reference site the Perequê Ecological Park. Toxic responses (burial activity and lethality) and biochemical biomarkers (GST, GR, GPx, LPO, MTs, AChE and DNA damage) were evaluated and then integrated with metal bioavailability and chemical concentrations to address the sediment quality in the area through the weight-of-evidence approach. A multivariate analysis identified linkages between biological responses and contamination. Results pointed that, despite being below the benchmarks of the US Environmental Protection Agency, there is slight metal contamination in the lower part of the basin which induces oxidative stress in C. fluminea; other toxic responses were sometimes attributed to As and Cr bioaccumulation. The sediment quality values (TEL-PEL values in mg/kg) were calculated for the current study for As (0.63-1.31), Cr (3.5-11.05), Cs (1.0-1.17), Cu (6.32-7.32), Ni (6.78-7.46), Ti (42.0-215), V (1.77-8.00). By comparison with other international guidelines, the sediment quality of the lower basin of the Vale de Ribeira does not identify a significant environmental risk.

  2. Subconscious Influence Across Cultures

    DTIC Science & Technology

    2010-01-01

    American‟s must be good for their word in order to influence others while still developing positive relationships. In low-context society , receiving...as Cooperative Negotiation Strategies are very seldom studied by leaders in hierarchical organizations , social influence techniques are also rarely

  3. Influencing Your Colleagues.

    ERIC Educational Resources Information Center

    Walker, Alice D.

    1993-01-01

    This fifteenth article in a series on the principles of the AECT (Association for Educational Communications and Technology) Code of Professional Ethics focuses on members using coercive means to influence decisions of colleagues, using an example of a professor trying to influence a colleague to include his name on a research proposal. (LRW)

  4. Link Influence Entropy

    NASA Astrophysics Data System (ADS)

    Singh, Priti; Chakraborty, Abhishek; Manoj, B. S.

    2017-01-01

    In this paper we propose a new metric, Link Influence Entropy (LInE), which describes importance of each node based on the influence of each link present in a network. Influence of a link can neither be effectively estimated using betweenness centrality nor using degree based probability measures. The proposed LInE metric which provides an effective way to estimate the influence of a link in the network and incorporates this influence to identify nodal characteristics, performs better compared to degree based entropy. We found that LInE can differentiate various network types which degree-based or betweenness centrality based node influence metrics cannot. Our findings show that spatial wireless networks and regular grid networks, respectively, have lowest and highest LInE values. Finally, performance analysis of LInE is carried out on a real-world network as well as on a wireless mesh network testbed to study the influence of our metric as well as influence stability of nodes in dynamic networks.

  5. Water and sediment toxicity of freshwater mussels from population crashes of Asiatic clams

    SciTech Connect

    Scheller, J.L.; Cherry, D.S.; Yeager, M.M.; Lynde, S.R.; Shepard, N.D.

    1994-12-31

    The Clinch River watershed in Virginia contains one of the most diverse communities of freshwater bivalves or unionids in North America. These communities are becoming depleted over the past few decades due to various point (industrial, municipal) and nonpoint (roadside and agricultural runoff) discharges. By the latter 1980`s, the Asiatic clam (Corbicula fluminea) had invaded most reaches of this system and may be becoming a contributing factor to the demise of native mussels by the natural release of toxic ammonia from dense population crashes during late summer, low flow conditions. When densities surpassed 1,500 clams/m{sup 2}, crashes resulting in >99% mortality have been observed in various areas of the river. Total ammonia release from dying clams reached and sustained 70 mg/L for several days in laboratory artificial stream experiments. These ammonia levels resulted in acute toxicity and reproductive chronic impairment to Daphnia magna in 10-day sediment toxicity tests. Pediveliger larvae of Corbicula were acutely sensitive (48 hr LC{sub 50}) to 1.72 mg/L total ammonia (O.05 mg/L unionized), mortality was 100% to juvenile and adult clams in 9 to 13 days at 16.1 mg/L total (0.74 mg/L unionized ammonia). Mussel glochidia were sensitive to 24-hr ammonia exposures (LC{sub 50} = 3.29 and 0.11 mg/L as total and unionized ammonia, respectively). Juvenile and adult mussels are predicted to be less sensitive members of the unionid life cycle as observed from earlier studies involving copper toxicity in the Clinch River.

  6. [Natural factors influencing sleep].

    PubMed

    Jurkowski, Marek K; Bobek-Billewicz, Barbara

    2007-01-01

    Sleep is a universal phenomenon of human and animal lives, although the importance of sleep for homeo-stasis is still unknown. Sleep disturbances influence many behavioral and physiologic processes, leading to health complications including death. On the other hand, sleep improvement can beneficially influence the course of healing of many disorders and can be a prognostic of health recovery. The factors influencing sleep have different biological and chemical origins. They are classical hormones, hypothalamic releasing and inhibitory hormones, neuropeptides, peptides and others as cytokines, prostaglandins, oleamid, adenosine, nitric oxide. These factors regulate most physiologic processes and are likely elements integrating sleep with physiology and physiology with sleep in health and disorders.

  7. Factors Influencing Army Maintenance

    DTIC Science & Technology

    1989-01-01

    ARI Research Note 89-11 (N 00 Factors Influencing Army Maintenance LOloD Debra C. Evans and J. Thomas Roth Applied Science Associates, Inc. for...1.2.7 .2.7.C.1 11. TITLE (Include Security ClassifIcarIon) Factors Influencing Army Maintenance i2. FERSONAL AuTtiOR(S) Evans, Debra C., and Roth, J...y • ’ Factors and variables that influence maintenance for systems and related manpower, per- sonnel, and training (MPT) characteristics were

  8. Influencing choice without awareness.

    PubMed

    Olson, Jay A; Amlani, Alym A; Raz, Amir; Rensink, Ronald A

    2015-12-01

    Forcing occurs when a magician influences the audience's decisions without their awareness. To investigate the mechanisms behind this effect, we examined several stimulus and personality predictors. In Study 1, a magician flipped through a deck of playing cards while participants were asked to choose one. Although the magician could influence the choice almost every time (98%), relatively few (9%) noticed this influence. In Study 2, participants observed rapid series of cards on a computer, with one target card shown longer than the rest. We expected people would tend to choose this card without noticing that it was shown longest. Both stimulus and personality factors predicted the choice of card, depending on whether the influence was noticed. These results show that combining real-world and laboratory research can be a powerful way to study magic and can provide new methods to study the feeling of free will. Copyright © 2015 Elsevier Inc. All rights reserved.

  9. Sex Differences in Influenceability

    ERIC Educational Resources Information Center

    Eagly, Alice H.

    1978-01-01

    Examines the hypothesis that women are more easily influenced than men by reviewing the literature on persuasion and conformity research. Persuasion research and conformity studies not involving group pressure show scant empirical support for sex differences. For group pressure conformity research, a substantial minority of studies support the…

  10. Tactics of Social Influence.

    ERIC Educational Resources Information Center

    Mehrabian, Albert

    In this book, the principles of behavior modification are presented as a set of guidelines for identifying recurrent behavior patterns and are then applied as techniques to change various undesirable behaviors. Progressively more complex steps toward behavior modification and its social influence are cited and illustrated in chapters which deal…

  11. Status, Numbers and Influence

    ERIC Educational Resources Information Center

    Melamed, David; Savage, Scott V.

    2013-01-01

    We develop a theoretical model of social influence in n-person groups. We argue that disagreement between group members introduces uncertainty into the social situation, and this uncertainty motivates people to use status characteristics to evaluate the merits of a particular opinion. Our model takes the numerical distribution of opinions and the…

  12. Status, Numbers and Influence

    ERIC Educational Resources Information Center

    Melamed, David; Savage, Scott V.

    2013-01-01

    We develop a theoretical model of social influence in n-person groups. We argue that disagreement between group members introduces uncertainty into the social situation, and this uncertainty motivates people to use status characteristics to evaluate the merits of a particular opinion. Our model takes the numerical distribution of opinions and the…

  13. Factors influencing plant invasiveness

    Treesearch

    Yvette Ortega; Dean Pearson

    2009-01-01

    Invasiveness of spotted knapweed and biological control agents. Dean and Yvette are examining the influence of drought on the invasiveness of spotted knapweed (Centaurea maculosa) and its susceptibility to herbivory by biological control agents. In collaboration with the University of Montana and Forest Health Protection, researchers have constructed 150...

  14. TANTRIK INFLUENCE ON SARNGADHARA

    PubMed Central

    Sharma, P. V.

    1984-01-01

    Tantra and Ayurveda are interrelated, particularly during medieval period, Tantra had great impact on the theory and practice of Ayurveda. Hitherto this aspect of history is not sufficiently explored. In this paper, influence of Tantra on Sarngadhara, a representative author of the medieval period, has been vividly brought out. PMID:22557393

  15. The Drive to Influence

    ERIC Educational Resources Information Center

    Rodriguez, Diego

    2017-01-01

    At the heart of the educational vocation is a drive to influence, to meaningfully affect the learning and development of others. For adult educators working in higher education, daily activities--from teaching classes to supervising student research to attending faculty meetings to sitting on advisory boards--are full of opportunities to…

  16. Ecological values of shallow-water habitats: Implications for the restoration of disturbed ecosystems

    USGS Publications Warehouse

    Lopez, C.B.; Cloern, J.E.; Schraga, T.S.; Little, A.J.; Lucas, L.V.; Thompson, J.K.; Burau, J.R.

    2006-01-01

    A presumed value of shallow-habitat enhanced pelagic productivity derives from the principle that in nutrient-rich aquatic systems phytoplankton growth rate is controlled by light availability, which varies inversely with habitat depth. We measured a set of biological indicators across the gradient of habitat depth within the Sacramento-San Joaquin River Delta (California) to test the hypothesis that plankton biomass, production, and pelagic energy flow also vary systematically with habitat depth. Results showed that phytoplankton biomass and production were only weakly related to phytoplankton growth rates whereas other processes (transport, consumption) were important controls. Distribution of the invasive clam Corbicula fluminea was patchy, and heavily colonized habitats all supported low phytoplankton biomass and production and functioned as food sinks. Surplus primary production in shallow, uncolonized habitats provided potential subsidies to neighboring recipient habitats. Zooplankton in deeper habitats, where grazing exceeded phytoplankton production, were likely supported by significant fluxes of phytoplankton biomass from connected donor habitats. Our results provide three important lessons for ecosystem science: (a) in the absence of process measurements, derived indices provide valuable information to improve our mechanistic understanding of ecosystem function and to benefit adaptive management strategies; (b) the benefits of some ecosystem functions are displaced by water movements, so the value of individual habitat types can only be revealed through a regional perspective that includes connectedness among habitats; and (c) invasive species can act as overriding controls of habitat function, adding to the uncertainty of management outcomes. ?? 2006 Springer Science+Business Media, Inc.

  17. Macrofouling control in nuclear power plants

    SciTech Connect

    Ekis, E.W. Jr.; Keoplin-Gall, S.M.; McCarthy, R.E.

    1991-11-01

    Macrofouling of cooling-water systems is one of the more significant and costly problems encountered in the nuclear power industry. Both marine and freshwater macroinvertebrates can be responsible for losses in plant availability because of plugged intakes and heat transfer equipment. There is a greater diversity of macrofouling organisms in marine waters than in fresh waters. Marine macrofouling organisms include barnacles, mollusks, bryozoans, and hydroids. Barnacles are crustaceans with feathery appendages, which allow them to attach to a variety of surfaces. They are a major cause of severe macrofouling because they can remain attached even after death. The major freshwater macrofouling organisms include the Asiatic Clam (Corbicula fluminea) and the newest freshwater macrofouler, the Zebra Mussel (Dreissena polymorpha). The introduction of the Zebra Mussel into the Great Lakes has created economic and ecological problems that will not easily be solved. The threat of intercontinental dispersal of the Zebra Mussel in America is serious. Research programs have been initiated around the country to develop control methods for this macrofouling problem. The various control methodologies can be classified in the following categories: biological, chemical, physical, and mechanical. Laboratory experiments were performed to evaluate the efficacy of Actibrom against mature Zebra Mussels.

  18. Survival, growth and condition of freshwater mussels: effects of municipal wastewater effluent.

    PubMed

    Nobles, Trey; Zhang, Yixin

    2015-01-01

    Freshwater mussels (Family Unionidae) are among the most imperiled group of organisms in the world, with nearly 65% of North American species considered endangered. Anthropogenic disturbances, including altered flow regimes, habitat alteration, and pollution, are the major driver of this group's decline. We investigated the effects of tertiary treated municipal wastewater effluent on survivorship, growth, and condition of freshwater mussels in experimental cages in a small Central Texas stream. We tested the effluent effects by measuring basic physical parameters of native three ridge mussels (Amblema plicata) and of non-native Asian clams (Corbicula fluminea), before and after 72-day exposure at four sites above and below a municipal wastewater treatment plant outfall. Survivorship and growth of the non-native Asian clams and growth and condition indices of the native three ridge mussels were significantly higher at the reference site above the outfall than in downstream sites. We attribute this reduction in fitness below the outfall to elevated nutrient and heavy metal concentrations, and the potential presence of other untested-for compounds commonly found in municipal effluent. These results, along with an absence of native mussels below the discharge, indicate a significant negative impact of wastewater effluent on both native and non-native mussels in the stream.

  19. Escherichia coli Reduction by Bivalves in an Impaired River Impacted by Agricultural Land Use.

    PubMed

    Ismail, Niveen S; Tommerdahl, Jake P; Boehm, Alexandria B; Luthy, Richard G

    2016-10-18

    Fecal indicator bacteria (FIB) are leading causes of impaired surface waters. Innovative and environmentally appropriate best management practices are needed to reduce FIB concentrations and associated risk. This study examines the ability of the native freshwater mussel Anodonta californiensis and an invasive freshwater clam Corbicula fluminea to reduce concentrations of the FIB Escherichia coli in natural waters. Laboratory batch experiments were used to show bivalve species-specific E. coli removal capabilities and to develop a relationship between bivalve size and clearance rates. A field survey within an impaired coastal river containing both species of bivalves in an agricultural- and grazing-dominated area of the central coast of California showed a significant inverse correlation between E. coli concentration and bivalve density. An in situ field spiking and sampling study showed filtration by freshwater bivalves resulting in 1-1.5 log10 reduction of E. coli over 24 h, and calculated clearance rates ranged from 1.2 to 7.4 L hr(-1) bivalve(-1). Results of this study show the importance of freshwater bivalves for improving water quality through the removal of E. coli. While both native and invasive bivalves can reduce E. coli levels, the use of native bivalves through integration into best management practices is recommended as a way to improve water quality and protect and encourage re-establishment of native bivalve species that are in decline.

  20. Photocatalytic ozonation using doped TiO2 catalysts for the removal of parabens in water.

    PubMed

    Gomes, João F; Leal, Inês; Bednarczyk, Katarzyna; Gmurek, Marta; Stelmachowski, Marek; Diak, Magdalena; Emília Quinta-Ferreira, M; Costa, Raquel; Quinta-Ferreira, Rosa M; Martins, Rui C

    2017-12-31

    Conventional wastewater treatments are inefficient for the removal of parabens. The aim of this study was finding a suitable solution using ozone and UVA irradiation combined with TiO2 catalysts doped with different noble metals (Ag, Pt, Pd, Au). Photocatalytic ozonation required lower amounts of ozone for higher efficiency on the removal of parabens, chemical oxygen demand (COD) and total organic carbon (TOC). The best catalyst for the initial contaminants degradation was 0.5% Ag-TiO2 leading to total parabens removal using 46mgO3/L. Due to the relative low mineralization achieved, the toxicity of the treated solutions was still compared with the initial one over several species (Vibrio fischeri, Lepidium sativum and Corbicula fluminea). All the treatments applied led to a clear decrease on the toxicity compared with initial mixture of parabens. From an economical point of view, it was concluded that the presence of UVA irradiation increased the energy consumption compared with catalytic ozonation with these catalysts but it can decrease the time of reaction. From the by-products analysis, it was concluded that hydroxylation appears to be the most significant reaction pathway and the main responsible for parabens degradation. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Derivation of aquatic predicted no-effect concentration (PNEC) for 2,4-dichlorophenol: comparing native species data with non-native species data.

    PubMed

    Jin, Xiaowei; Zha, Jinmiao; Xu, Yiping; Wang, Zijian; Kumaran, Satyanarayanan Senthil

    2011-09-01

    2,4-Dichlorophenol (2,4-DCP) is known as an important chemical intermediate and an environmental endocrine disruptor. There is no paper dealing with the predicted no-effect concentration (PNEC) of 2,4-DCP, mainly due to shortage of chronic and site-specific toxicity data. In the present study, toxicity data was obtained from the tests using six Chinese native aquatic species. The HC(5) (hazardous concentration for 5% of species) was derived based on the constructed species sensitivity distribution (SSD), which was compared with that derived from literature toxicity data of non-native species. For invertebrates, the survival no-observed effect concentrations (NOECs) were 0.05 and 1.00 mg L(-1) for Macrobrachium superbum and Corbicula fluminea, respectively. NOECs based on fishes' growth were 0.10, 0.20 and 0.40 mg L(-1) for Mylopharyngodon piceus, Plagiognathops microlepis and Erythroculter ilishaeformis, respectively. For aquatic plant Soirodela polyrhiza, NOEC based on concentration of chlorophyll was 1.00 mg L(-1). A final PNEC calculated using the SSD approach with a 50% certainty based on different taxa ranged between 0.008 and 0.045 mg L(-1). There is no significant difference between HC(5) derived from native and that from non-native taxa.

  2. Occurrence and Distribution of Organochlorine Compounds in Biological Tissue and Bed Sediment From Streams in the Trinity River Basin, Texas, 1992-93

    USGS Publications Warehouse

    Moring, J. Bruce

    1997-01-01

    This report describes the occurrence and distribution of organochlorine compounds in biological tissue and bed sediment from the Trinity River Basin study area of the National Water-Quality Assessment Program. Concentrations of organochlorine pesticides, polychlorinated biphenyls (PCBs), and other organochlorine compounds were determined in biological tissue and surficial bed sediment from 16 stream sites in the Trinity River Basin of east-central Texas. Asiatic clams (Corbicula fluminea) were collected at 10 sites, and fish, including blue catfish (Ictalurus furcatus), common carp (Cyprinus carpio), bluegill (Lepomis cyanellus), and yellow bullhead (Ameiurus natalis) were collected at all mainstem and two tributary sites. Thirty of the 36 compounds analyzed in biological tissue or surficial bed sediment were detected in one or both media. Overall, more organochlorine compounds were detected in bed sediment than in biological tissue; however, various chlordane isomers, DDT metabolites, and PCBs were detected more frequently in tissue than in sediment. The chlordane isomers and PCBs that were detected more frequently in biological tissue also were detected more frequently at urban sites than at agricultural sites. Organochlorine compound concentrations generally were highest in fish tissue from Trinity River mainstem sites. Fish tissue from the mainstem sites contained a higher percentage of lipids than did fish- and clam-tissue samples from the tributary sites.

  3. A 3D individual-based aquatic transport model for the assessment of the potential dispersal of planktonic larvae of an invasive bivalve.

    PubMed

    Hoyer, Andrea B; Wittmann, Marion E; Chandra, Sudeep; Schladow, S Geoffrey; Rueda, Francisco J

    2014-12-01

    The unwanted impacts of non-indigenous species have become one of the major ecological and economic threats to aquatic ecosystems worldwide. Assessing the potential dispersal and colonization of non-indigenous species is necessary to prevent or reduce deleterious effects that may lead to ecosystem degradation and a range of economic impacts. A three dimensional (3D) numerical model has been developed to evaluate the local dispersal of the planktonic larvae of an invasive bivalve, Asian clam (Corbicula fluminea), by passive hydraulic transport in Lake Tahoe, USA. The probability of dispersal of Asian clam larvae from the existing high density populations to novel habitats is determined by the magnitude and timing of strong wind events. The probability of colonization of new near-shore areas outside the existing beds is low, but sensitive to the larvae settling velocity ws. High larvae mortality was observed due to settling in unsuitable deep habitats. The impact of UV-radiation during the pelagic stages, on the Asian clam mortality was low. This work provides a quantification of the number of propagules that may be successfully transported as a result of natural processes and in function of population size. The knowledge and understanding of the relative contribution of different dispersal pathways, may directly inform decision-making and resource allocation associated with invasive species management.

  4. Fauna Europaea: Mollusca – Bivalvia

    PubMed Central

    2015-01-01

    Abstract Fauna Europaea provides a public web-service with an index of scientific names (including important synonyms) of all living European land and freshwater animals, their geographical distribution at country level (up to the Urals, excluding the Caucasus region), and some additional information. The Fauna Europaea project covers about 230,000 taxonomic names, including 130,000 accepted species and 14,000 accepted subspecies, which is much more than the originally projected number of 100,000 species. This represents a huge effort by more than 400 contributing specialists throughout Europe and is a unique (standard) reference suitable for many users in science, government, industry, nature conservation and education. For the Mollusca-Bivalvia, data from 5 families (Margaritiferidae, Unionidae, Sphaeriidae, Cyrenidae, Dreissenidae) containing 55 species are included in this paper. European freshwater bivalves belong to the Orders Unionoida and Cardiida. All the European unionoids are included in the superfamily Unionoidea, the freshwater mussels or naiads. The European cardiids belong to the following three superfamilies: Cardioidea, Cyrenoidea and Dreissenoidea. Among the Unionoidea there are the most imperilled animal groups on the planet while the Cardioidea includes the cosmopolitan genus Pisidium, the Cyrenoidea the Asiatic clam (Corbicula fluminea) and the Dreissenoidea the famous invasive zebra mussel (Dreissena polymorpha). Basic information is summarized on their taxonomy and biology. Tabulations include a complete list of the current estimated families, genera and species. PMID:26311403

  5. Levels and distribution of polybrominated diphenyl ethers in water, surface sediments, and bivalves from the San Francisco Estuary.

    PubMed

    Oros, Daniel R; Hoover, Dale; Rodigari, Francois; Crane, David; Sericano, Jose

    2005-01-01

    Polybrominated diphenyl ethers (PBDEs) were found in water, surface sediments, and bivalve samples that were collected from the San Francisco Estuary in 2002. sigmaPBDE concentrations in water samples ranged from 3 to 513 pg/ L, with the highest concentrations found in the Lower South Bay (range 103-513 pg/L) region, which receives approximately 26% of the Estuary's wastewater treatment plant effluents. The sigmaPBDEs in sediments ranged from below detection limits to 212 ng/g dry wt, with the highest concentration found at a South Bay station (212 ng/g dry wt), which was up to 3 orders of magnitude higher than other stations. The sigmaPBDE concentrations ranged from 9 to 64 ng/g dry wt in oysters (Crassostrea gigas), from 13 to 47 ng/g dry wt in mussels (Mytilus californianus), and from 85 to 106 ng/g dry wt in clams (Corbicula fluminea). Only three PBDE congeners were detected in bivalves, BDE-47, BDE-99, and BOE-100; these are the most bioaccumulative congeners from the commercial Penta-BDE mixture.

  6. Survival, Growth and Condition of Freshwater Mussels: Effects of Municipal Wastewater Effluent

    PubMed Central

    Nobles, Trey; Zhang, Yixin

    2015-01-01

    Freshwater mussels (Family Unionidae) are among the most imperiled group of organisms in the world, with nearly 65% of North American species considered endangered. Anthropogenic disturbances, including altered flow regimes, habitat alteration, and pollution, are the major driver of this group's decline. We investigated the effects of tertiary treated municipal wastewater effluent on survivorship, growth, and condition of freshwater mussels in experimental cages in a small Central Texas stream. We tested the effluent effects by measuring basic physical parameters of native three ridge mussels (Amblema plicata) and of non-native Asian clams (Corbicula fluminea), before and after 72-day exposure at four sites above and below a municipal wastewater treatment plant outfall. Survivorship and growth of the non-native Asian clams and growth and condition indices of the native three ridge mussels were significantly higher at the reference site above the outfall than in downstream sites. We attribute this reduction in fitness below the outfall to elevated nutrient and heavy metal concentrations, and the potential presence of other untested-for compounds commonly found in municipal effluent. These results, along with an absence of native mussels below the discharge, indicate a significant negative impact of wastewater effluent on both native and non-native mussels in the stream. PMID:26042840

  7. The effects of acrylamide polyelectrolytes on aquatic organisms: relating toxicity to chain architecture.

    PubMed

    Costa, R; Pereira, J L; Gomes, J; Gonçalves, F; Hunkeler, D; Rasteiro, M G

    2014-10-01

    Understanding the inherent toxicity of water-soluble synthetic polyelectrolytes is critical for adequate risk management as well as enhancing product design when biological activity is a key performance index (e.g. for application in biofouling bivalves' control). The toxicity of two cationic acrylamide copolymers with different chain branching degree was evaluated. Standard ecotoxicity tests were conducted with microalgae and daphnids. The susceptibility of Corbicula fluminea, as a biofouling bivalve, was also evaluated. The effect of polyelectrolyte on the test media viscosity and the polymer chain size distributions under the experimental conditions were also examined. The susceptibility of the microalgae to both polymers was similar. As the complexity and size of the test organisms increased, differences in toxicity due to different chain architecture were noticeable. The more branched polymer was significantly less toxic to both daphnids and the bivalves, which could be linked to the distinctive features of its bimodal size chain distribution. This architecture resulted in both more compact globular molecules and the formation of aggregates, which reduce the polymer interaction with the biological surfaces. The results of this study promote the incorporation of environmental considerations in polyelectrolyte development and contribute to the design of improved solutions for controlling biofouling bivalves. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Effects of calcium on the uptake and elimination of cadmium and zinc in Asiatic clams.

    PubMed

    Qiu, J-W; Xie, Z-C; Wang, W-X

    2005-02-01

    We examined the effects of Ca, one of the major ions contributing to water hardness, on the uptake and elimination of Cd and Zn in the Asiatic clam Corbicula fluminea, a common bivalve species in the rivers and streams of Southern China. Over the wide range of dissolved Cd (4.5 to 446 nM) and Zn (15.3 to 1529 nM) concentrations, uptake of both metals increased with increasing dissolved metal concentration, showing Michaelis-Menten-type saturation kinetics. At each tested metal concentration, increased Ca concentration led to a significantly lower metal uptake. When the Ca, Cd, Zn concentrations were expressed as free-ion activities, Cd and Zn uptake data fitted the Michaelis-Menten inhibition model well. We also quantified the effects of the two Ca blockers on metal uptake by the clams. Verapamil significantly inhibited the uptake Cd and Zn, but the inhibitive effect of lanthanum on metal uptake was more evident for Cd than for Zn. Ca did not significantly affect the assimilation efficiency of either metal from ingested phytoplankton, nor did it affect the elimination of the two metals during a 1-month depuration period. Our study has shown that Ca inhibited the uptake of metals from water; such an effect could be predicted based on the free-metal ion activities. Ca did not seem to have a direct effect on metal assimilation from food or metal elimination from the bivalve.

  9. Cd, Cu, Pb and Zn in clams and sediments from an impacted estuary by the oil industry in the southwestern Gulf of Mexico: concentrations and bioaccumulation factors.

    PubMed

    Ruelas-Inzunza, J; Spanopoulos-Zarco, P; Páez-Osuna, F

    2009-12-01

    With the objective of estimating the temporal variation and bioavailability of Cd, Cu, Pb and Zn in Coatzacoalcos estuary, the biota-sediment accumulation factors (BSAF) were calculated. For this purpose, surficial sediments and clams from 14 selected sites were collected during three climatic seasons. In surficial sediments, highest levels of Cd and Cu were measured during the rainy season near to the industrial area of Minatitlan, while highest concentrations of Pb and Zn were registered during the windy season in sediments collected near to the industrial area of Coatzacoalcos. Considering all the sampling seasons and bivalve species, average metal concentrations followed the order Zn > Cu > Cd > Pb. BSAF ranged from 0.01 (Pb) in Corbicula fluminea during the hot season to 25.1 (Cd) in Polymesoda caroliniana during the windy season. BSAF of Cd, Cu and Zn were higher during the windy season; in the case of Pb, the dry season was the time when such figure was more elevated. It can be stated that Polymesoda caroliniana is a net accumulator of Cd and Zn and a weak accumulator of Pb for the studied estuary.

  10. Using watershed characteristics, sediment, and tissue of resident mollusks to identify potential sources of trace elements to streams in a complex agricultural landscape.

    PubMed

    Ciparis, Serena; Schreiber, Madeline E; Voshell, J Reese

    2012-05-01

    Trace elements used in animal feed additives can be introduced to aquatic environments through application of manures from animal feeding operations to agricultural land as fertilizer. The use of poultry feed additives containing arsenic (As) is of particular concern in the Shenandoah River watershed (Virginia, USA), an agricultural landscape with a high density of poultry operations. This study investigated the relationship between watershed characteristics of Shenandoah River tributaries and trace element concentrations in streambed sediment and tissue of resident mollusks, including: Asian clams (Corbicula fluminea), which are commonly used biomonitors, and pleurocerid snails (Leptoxis carinata), which are generally understudied. Results failed to support the primary hypothesis of a predictive relationship between watershed densities of poultry operations and As concentrations in sediment and mollusk tissue. However, there were statistical relationships between land use in tributary watersheds and other trace elements in sediment (Cu, Mn, Pb, Zn) and tissue (Cd, Hg, Pb). Principal components analysis of the sediment data suggested a possible geologic source of As at some sites. Tissue concentrations of As were significantly higher in snails than in clams, but clams accumulated higher concentrations of other trace elements (Cd, Cr, Hg, Pb, Se). Snails may be useful biomonitors of environmental As, but appear to be less suitable than clams for studies of landscape sources of other trace elements.

  11. Development of biological indices for identifying and evaluating impacts of pollutants on freshwater ecosystems. Final report, June 1975-October 1980

    SciTech Connect

    Cairns, J. Jr.; Cherry, D.S.

    1980-09-30

    The ten Research Areas reported included: (1) the development of functional indices for identifying and evaluating impacts of pollutants on Aufwuchs communities, (2) relationship of protozoan colonization rates to the eutrophication process, (3) testing of methods to determine the functioning of zooplankton communities subjected to entrainment stress, (4) the use of the first steps of detritus processing (microbial decomposition) as a technique for assessing pollutional stress on aquatic communities in a river system, (5) relationship of protozoan invasion and extinction rate to the eutrophication process, (6) extension of present early colonization studies to the simultaneous evaluation of natural environmental parameters and power plant effluents and application of the early colonization approach to microbial communities in streams of the New River drainage, (7) testing of single species-community responses of protozoans from selected heavy metals, (8) the effects of selected power plant pollutants on grazer utilization of Aufwuchs, (9) investigation of bioconcentration and bioaccumulation mechanisms of the Asiatic clam (Corbicula fluminea) populations in field artificial streams and laboratory microcosms with reference to physical chemistry and diet alterations, and (10) investigation of the homeostatic regulation in bluegill sunfish following acute hypothermal shock and to other power plant related effluents.

  12. Zebra mussels (Dreissena polymorpha) as a biomonitor of trace elements along the southern shoreline of Lake Michigan.

    PubMed

    Shoults-Wilson, W Aaron; Elsayed, Norhan; Leckrone, Kristen; Unrine, Jason

    2015-02-01

    The invasive zebra mussel (Dreissena polymorpha) has become an accepted biomonitor organism for trace elements, but it has yet to be studied along the Lake Michigan shoreline. Likewise, the relationships between tissue concentrations of elements, organism size, and sediment concentrations of elements have not been fully explained. The present study found that a variety of allometric variables such as length, dry tissue mass, shell mass, organism condition indices, and shell thickness index were useful in explaining intrasite variability in elemental concentrations. The flesh condition index (grams of tissue dry mass per gram of shell mass) explained variability at the most sites for most elements. Once allometric intrasite variability was taken into account, additional significant differences were found between sites, although the net effect was small. Significant positive relationships between sediment and tissue concentrations were found for Pb and Zn, with a significant negative relationship for Cd. It was also found that Cu and Zn concentrations in tissues increased significantly along the shoreline in the southeasterly direction, whereas Hg increased in a northwesterly direction. Opportunistic sampling found that zebra mussels accumulate significantly higher concentrations of nearly all elements analyzed compared to Asian clams (Corbicula fluminea) at the same site. The present study demonstrates the need to fully explain natural sources of variability before using biomonitors to explain spatial distributions of trace elements.

  13. Fluidized bed ash and passive treatment reduce the adverse effects of acid mine drainage on aquatic organisms.

    PubMed

    Porter, Clint M; Nairn, Robert W

    2010-10-15

    Elevated concentrations of acidity and metals in acid mine drainage (AMD) may be effectively addressed by active and passive treatment technologies. However, typical evaluations consider only chemical water quality with little if any regard for biological metrics. Robust evaluations including both chemical and biological indicators of water quality improvement are needed. In this study, injection of alkaline fluidized bed ash (FBA) into a flooded underground coal mine was coupled with a five-cell passive treatment system to ameliorate an abandoned AMD discharge in eastern Oklahoma. The passive system included process units promoting both aerobic and anaerobic treatment mechanisms. Resulting water quality changes and biological responses were evaluated. Organisms of two distinct functional groups (the filter-feeding mollusk Corbicula fluminea and the wide-spectrum feeding fish Lepomis macrochirus) were exposed to mine waters in several treatment cells. The combination of treatment technologies was hypothesized to limit potential negative effects on these aquatic organisms. Tissues were harvested and analyzed for concentrations of several metals (Al, Fe, Mn, Mg, Ca, Ni, Cu and Zn) of interest. Organismal responses, such as hepatosomatic index, condition factor, and condition index, did not vary significantly among organisms exposed within different treatment cells when compared to non-AMD impaired waters. Metal tissue accumulation trends, compared to aqueous concentrations, were observed for Fe, Ni and Zn. Exposure experiments with these two organisms indicated that FBA introductions coupled with passive treatment decreased the potential adverse effects of AMD to biological systems. Copyright © 2010 Elsevier B.V. All rights reserved.

  14. Mollusk Survey in the Snake River, Hells Canyon, USA

    NASA Astrophysics Data System (ADS)

    Lester, G. T.; Falter, C. M.; Myers, R.; Richards, D. C.

    2005-05-01

    We conducted surveys and several experiments on mollusks, focusing on listed, rare, or sensitive species, in reservoirs, tributaries and main stem of the Snake River in Hells Canyon Idaho and Oregon, USA. The most important result of this study was documentation of the undescribed Taylorconcha sp. throughout the Snake River in Hells Canyon, although we did not find Taylorconcha sp. within 12 miles downstream of HCD, most likely due to river armoring. Additional results include: 1) the mollusk community was similar throughout the Snake River, except where the Salmon River entered the Snake River; 2) Taylorconcha sp. abundance was directly related to the abundance of Potamopyrgus antipodarum, a highly invasive snail, and with moderate abundance of detritus; 3) hand picking cobbles was more efficient than suction dredging for snails and limpets but not for bivalves, 4) the most abundant mollusks were two invasive species, P. antipodarum and Corbicula fluminea and; 5) only one live small colony of native Gonidea angulata (Unionidae) and no live Anodonta californiensis (Unionidae) were found in the survey.

  15. Protocol for Monitoring Metals in Ozark National Scenic Riverways, Missouri: Version 1.0

    USGS Publications Warehouse

    Schmitt, Christopher J.; Brumbaugh, William G.; Besser, John M.; Hinck, Jo Ellen; Bowles, David E.; Morrison, Lloyd W.; Williams, Michael H.

    2008-01-01

    The National Park Service is developing a monitoring plan for the Ozark National Scenic Riverways in southeastern Missouri. Because of concerns about the release of lead, zinc, and other metals from lead-zinc mining to streams, the monitoring plan will include mining-related metals. After considering a variety of alternatives, the plan will consist of measuring the concentrations of cadmium, cobalt, lead, nickel, and zinc in composite samples of crayfish (Orconectes luteus or alternate species) and Asian clam (Corbicula fluminea) collected periodically from selected sites. This document, which comprises a protocol narrative and supporting standard operating procedures, describes the methods to be employed prior to, during, and after collection of the organisms, along with procedures for their chemical analysis and quality assurance; statistical analysis, interpretation, and reporting of the data; and for modifying the protocol narrative and supporting standard operating procedures. A list of supplies and equipment, data forms, and sample labels are also included. An example based on data from a pilot study is presented.

  16. Toxicity of a traditional molluscicide to asian clam veligers

    USGS Publications Warehouse

    Layhee, Megan J.; ,; Miho Yoshioka,; Bahram Farokhkish,; ,; Gross, Jackson A.; Sepulveda, Adam J.

    2014-01-01

    Aquaculture and hatchery industries are in need of effective control methods to reduce the risk of spreading aquatic invasive species, such as the Asian clam Corbicula fluminea, through aquaculture and hatchery activities. The planktonic nature of Asian clam veligers enables this life stage to enter water-based infrastructure undetected, including hatchery trucks used to stock fish. Once in hatchery trucks, veligers can disperse overland and establish in previously uninvaded habitats. As a result, there is a need to develop techniques that result in veliger mortality but do not harm fish. In September 2012, we conducted laboratory trials to determine if a molluscicide (750 mg/L potassium chloride and 25 mg/L formalin) commonly used to kill zebra mussel (Dreissena polymorpha) veligers in hatchery trucks can also effectively kill Asian clam veligers. We exposed Asian clam veligers to this molluscicide for 1, 3, and 5 h in each of two water types: deionized water and filtered lake water. We found ,20% mortality at the 1-h exposure period and 100% mortality at both the 3-h and 5-h exposure periods, regardless of water type. This laboratory study represents an important step toward reducing the spread of Asian clams by aquaculture facilities.

  17. Protocol for monitoring metals in Ozark National Scenic Riverways, Missouri: Version 1.0

    USGS Publications Warehouse

    Schmitt, Christopher J.; Brumbaugh, William G.; Besser, John M.; Hinck, Jo Ellen; Bowles, David E.; Morrison, Lloyd W.; Williams, Michael H.

    2008-01-01

    The National Park Service is developing a monitoring plan for the Ozark National Scenic Riverways in southeastern Missouri. Because of concerns about the release of lead, zinc, and other metals from lead-zinc mining to streams, the monitoring plan will include mining-related metals. After considering a variety of alternatives, the plan will consist of measuring the concentrations of cadmium, cobalt, lead, nickel, and zinc in composite samples of crayfish (Orconectes luteus or alternate species) and Asian clam (Corbicula fluminea) collected periodically from selected sites. This document, which comprises a protocol narrative and supporting standard operating procedures, describes the methods to be employed prior to, during, and after collection of the organisms, along with procedures for their chemical analysis and quality assurance; statistical analysis, interpretation, and reporting of the data; and for modifying the protocol narrative and supporting standard operating procedures. A list of supplies and equipment, data forms, and sample labels are also included. An example based on data from a pilot study is presented.

  18. Diet and population metrics of the introduced blue catfish population in the Altamaha, River, GA

    USGS Publications Warehouse

    Bonvechio, Timothy F.; Jennings, Cecil A.

    2011-01-01

    Blue catfish (Ictalurus furcatus) were first detected in the Altamaha River, Georgia, during an access creel survey in 2005 and subsequently in 2006 during annual ictalurid sampling. Introduction of this species in the Altamaha River is believed to have occurred via escape from normal upstream reservoir releases from Lake Sinclair and Lake Oconee. Relative abundance, as indexed by electrofishing catch rate (fish per hour), has increased from 2.9±1.0 SE in 2006 to 38.8±8.2 SE in 2011. The size of blue catfish captured ranged from 56 to 820 mm total length and 0.001 to 7.7 kg. Using otoliths obtained in 2010 (n=214), age of fish ranged from 0 to 6 yrs, which indicated a relatively young population. The catch-curve analysis resulted in an instantaneous mortality rate (Z) of 0.75. Despite concerns of blue catfish predation on native fishes and mussels, a diet analysis of blue catfish (n=257) obtained in 2010 revealed that diets of fish in all size groups were dominated by the introduced Asiatic clam (Corbicula fluminea). This study describes a recently introduced blue catfish population in an Atlantic coastal plain river and provides insight on possible ecological effects during the early phases of establishment. These results offer an early status assessment of the invasion dynamics before the system has had time to reach a new equilibrium state.

  19. Range expansion of an exotic Siberian prawn to the Lower Snake River

    USGS Publications Warehouse

    Haskell, Craig A.; Baxter, Rex D.; Tiffan, Kenneth F.

    2006-01-01

    The introduction of non-native plant and animal species in aquatic systems is of increasing concern because of their potentially negative ecological and economic impacts (Sytsma et al. 2004). There are many examples of food web repercussions resulting from non-native invertebrate introductions. For example, in Flathead Lake, Montana, the kokanee salmon (Oncorhynchus nerka) population crashed after the introduction of a planktivorous mysid, My-sis relicta caused restructuring of the zooplankton community (Spencer et al. 1991) and the introduc-tion of the spiny water flea (Bythotrephes spp.) to the Great Lakes also restructured zooplankton communities (Barbiero and Tuchman 2004). The zebra mussel (Dreissena polymorpha) has nearly extirpated some native unionid clams through competition for food and shell fouling (Strayer 1999). In San Francisco Bay, California, one of the most highly invaded estuaries in the world (Cohen and Carlton 1998), the benthic fauna has been highly modified by the introduction of hundreds of exotic invertebrates including the Chinese mitten crab (Eriocheir sinensis) and the Asian clam, Potamocorbula amurensis. Non-native invertebrate species, including the New Zealand mud snail (Potamopyrgus antipodarum) and an-other Asian clam, Corbicula fluminea, have also been introduced to the Columbia River (Sytsma et al. 2004), but the ecological effects to Columbia River species are largely unknown.

  20. Bioaccumulation and trophic dilution of human pharmaceuticals across trophic positions of an effluent-dependent wadeable stream

    PubMed Central

    Du, Bowen; Haddad, Samuel P.; Luek, Andreas; Scott, W. Casan; Saari, Gavin N.; Kristofco, Lauren A.; Connors, Kristin A.; Rash, Christopher; Rasmussen, Joseph B.; Chambliss, C. Kevin; Brooks, Bryan W.

    2014-01-01

    Though pharmaceuticals are increasingly observed in a variety of organisms from coastal and inland aquatic systems, trophic transfer of pharmaceuticals in aquatic food webs have not been reported. In this study, bioaccumulation of select pharmaceuticals was investigated in a lower order effluent-dependent stream in central Texas, USA, using isotope dilution liquid chromatography–tandem mass spectrometry (MS). A fish plasma model, initially developed from laboratory studies, was tested to examine observed versus predicted internal dose of select pharmaceuticals. Pharmaceuticals accumulated to higher concentrations in invertebrates relative to fish; elevated concentrations of the antidepressant sertraline and its primary metabolite desmethylsertraline were observed in the Asian clam, Corbicula fluminea, and two unionid mussel species. Trophic positions were determined from stable isotopes (δ15N and δ13C) collected by isotope ratio-MS; a Bayesian mixing model was then used to estimate diet contributions towards top fish predators. Because diphenhydramine and carbamazepine were the only target compounds detected in all species examined, trophic magnification factors (TMFs) were derived to evaluate potential trophic transfer of both compounds. TMFs for diphenhydramine (0.38) and carbamazepine (1.17) indicated neither compound experienced trophic magnification, which suggests that inhalational and not dietary exposure represented the primary route of uptake by fish in this effluent-dependent stream. PMID:25313153

  1. Influence plots for LASSO

    SciTech Connect

    Jang, Dae -Heung; Anderson-Cook, Christine Michaela

    2016-11-22

    With many predictors in regression, fitting the full model can induce multicollinearity problems. Least Absolute Shrinkage and Selection Operation (LASSO) is useful when the effects of many explanatory variables are sparse in a high-dimensional dataset. Influential points can have a disproportionate impact on the estimated values of model parameters. Here, this paper describes a new influence plot that can be used to increase understanding of the contributions of individual observations and the robustness of results. This can serve as a complement to other regression diagnostics techniques in the LASSO regression setting. Using this influence plot, we can find influential points and their impact on shrinkage of model parameters and model selection. Lastly, we provide two examples to illustrate the methods.

  2. Influence plots for LASSO

    DOE PAGES

    Jang, Dae -Heung; Anderson-Cook, Christine Michaela

    2016-11-22

    With many predictors in regression, fitting the full model can induce multicollinearity problems. Least Absolute Shrinkage and Selection Operation (LASSO) is useful when the effects of many explanatory variables are sparse in a high-dimensional dataset. Influential points can have a disproportionate impact on the estimated values of model parameters. Here, this paper describes a new influence plot that can be used to increase understanding of the contributions of individual observations and the robustness of results. This can serve as a complement to other regression diagnostics techniques in the LASSO regression setting. Using this influence plot, we can find influential pointsmore » and their impact on shrinkage of model parameters and model selection. Lastly, we provide two examples to illustrate the methods.« less

  3. Trust and Influence

    DTIC Science & Technology

    2013-03-06

    how humans establish, maintain, and repair trust of humans and technological systems) and the science of influence (i.e., understanding how to shape...factors that shape reliance in complex human -machine interactions • Cross-Cultural Trust – identify the antecedents of trust in different cultures...actions of others with little ability to monitor their actions (Mayer et al., 1995) Assumptions: •Trust as a human phenomenon •Trust

  4. Comment: Respecifying Emotional Influence

    PubMed Central

    Parkinson, Brian

    2017-01-01

    To what extent does the level of overlap between social appraisal and social referencing depend upon the particular definitions adopted when following different research agendas? I argue that processes of both kinds fall under the more inclusive heading of relation alignment. Relation alignment also covers emotional influence that is not mediated by the communication of appraisal. Similarities, interdependences, and distinctions between these various relation-alignment processes warrant further investigation. PMID:28804511

  5. Comment: Respecifying Emotional Influence.

    PubMed

    Parkinson, Brian

    2017-07-01

    To what extent does the level of overlap between social appraisal and social referencing depend upon the particular definitions adopted when following different research agendas? I argue that processes of both kinds fall under the more inclusive heading of relation alignment. Relation alignment also covers emotional influence that is not mediated by the communication of appraisal. Similarities, interdependences, and distinctions between these various relation-alignment processes warrant further investigation.

  6. American Influence on Korean Education.

    ERIC Educational Resources Information Center

    Kim, Hyung-chan

    1982-01-01

    Discusses American influences on Korean education, considering the influence of American Protestant missionaries (1886-1945), relationship between American military government and Korean education, and educational cooperation between Korea and America since 1948. (JN)

  7. Variables influencing cardiovascular function.

    PubMed

    Fitzsimmons, L; Shively, M; Verderber, A

    1991-07-01

    Two studies are reviewed, one regarding the effects of music therapy on psychophysiologic stress in coronary care unit patients and one regarding the effects of age and gender on cardiovascular autonomic reactivity in healthy adults. Music therapy is determined to be safe for coronary care unit patients and effective in modulating the psychophysiologic manifestations of stress. The second study suggests that age--gender interactions may influence autonomic cardiovascular responsiveness. It is suggested that older adults be taught methods to reduce straining, so that rapid transient changes in blood pressure are avoided.

  8. Superintendents: The Key Influence Agents.

    ERIC Educational Resources Information Center

    Powell, Randy

    1990-01-01

    By the nature of their positions in schools, administrators are either influence agents or targets. Based on personal interviews with 140 Oregon administrators and a survey of 319 administrators around the state, this article highlights administrators' comments about their administrative influence and about constraints on their influence.…

  9. Multiple detectors "Influence Method".

    PubMed

    Rios, I J; Mayer, R E

    2016-05-01

    The "Influence Method" is conceived for the absolute determination of a nuclear particle flux in the absence of known detector efficiency and without the need to register coincidences of any kind. This method exploits the influence of the presence of one detector in the count rate of another detector, when they are placed one behind the other and define statistical estimators for the absolute number of incident particles and for the efficiency (Rios and Mayer, 2015a). Its detailed mathematical description was recently published (Rios and Mayer, 2015b) and its practical implementation in the measurement of a moderated neutron flux arising from an isotopic neutron source was exemplified in (Rios and Mayer, 2016). With the objective of further reducing the measurement uncertainties, in this article we extend the method for the case of multiple detectors placed one behind the other. The new estimators for the number of particles and the detection efficiency are herein derived. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Markov Influence Diagrams.

    PubMed

    Díez, Francisco J; Yebra, Mar; Bermejo, Iñigo; Palacios-Alonso, Miguel A; Calleja, Manuel Arias; Luque, Manuel; Pérez-Martín, Jorge

    2017-02-01

    Markov influence diagrams (MIDs) are a new type of probabilistic graphical model that extends influence diagrams in the same way that Markov decision trees extend decision trees. They have been designed to build state-transition models, mainly in medicine, and perform cost-effectiveness analyses. Using a causal graph that may contain several variables per cycle, MIDs can model various patient characteristics without multiplying the number of states; in particular, they can represent the history of the patient without using tunnel states. OpenMarkov, an open-source tool, allows the decision analyst to build and evaluate MIDs-including cost-effectiveness analysis and several types of deterministic and probabilistic sensitivity analysis-with a graphical user interface, without writing any code. This way, MIDs can be used to easily build and evaluate complex models whose implementation as spreadsheets or decision trees would be cumbersome or unfeasible in practice. Furthermore, many problems that previously required discrete event simulation can be solved with MIDs; i.e., within the paradigm of state-transition models, in which many health economists feel more comfortable.

  11. Vehicular road influence areas

    NASA Astrophysics Data System (ADS)

    Huertas, María E.; Huertas, José I.; Valencia, Alexander

    2017-02-01

    Vehicle operation over paved and unpaved roads is an emission source that significantly contributes to air pollution. Emissions are derived from vehicle exhaust pipes and re-suspension of particulate matter generated by wind erosion and tire to road surface interactions. Environmental authorities require a methodology to evaluate road impact areas, which enable managers to initiate counter-measures, particularly under circumstances where historic meteorological and/or air quality data is unavailable. The present study describes an analytical and experimental work developed to establish a simplified methodology to estimate the area influenced by vehicular roads. AERMOD was chosen to model pollutant dispersion generated by two roads of common attributes (straight road over flat terrain) under the effects of several arbitrary chosen weather conditions. The resulting pollutant concentration vs. Distance curves collapsed into a single curve when concentration and distance were expressed as dimensionless numbers and this curve can be described by a beta distribution function. This result implied that average concentration at a given distance was proportional to emission intensity and that it showed minor sensitivity to meteorological conditions. Therefore, road influence was defined by the area adjacent to the road limited by distance at which the beta distribution function equaled the limiting value specified by the national air quality standard for the pollutant under consideration.

  12. Diffusion Influenced Adsorption Kinetics.

    PubMed

    Miura, Toshiaki; Seki, Kazuhiko

    2015-08-27

    When the kinetics of adsorption is influenced by the diffusive flow of solutes, the solute concentration at the surface is influenced by the surface coverage of solutes, which is given by the Langmuir-Hinshelwood adsorption equation. The diffusion equation with the boundary condition given by the Langmuir-Hinshelwood adsorption equation leads to the nonlinear integro-differential equation for the surface coverage. In this paper, we solved the nonlinear integro-differential equation using the Grünwald-Letnikov formula developed to solve fractional kinetics. Guided by the numerical results, analytical expressions for the upper and lower bounds of the exact numerical results were obtained. The upper and lower bounds were close to the exact numerical results in the diffusion- and reaction-controlled limits, respectively. We examined the validity of the two simple analytical expressions obtained in the diffusion-controlled limit. The results were generalized to include the effect of dispersive diffusion. We also investigated the effect of molecular rearrangement of anisotropic molecules on surface coverage.

  13. Influence of External Fields

    NASA Astrophysics Data System (ADS)

    Wagner, M. R.; Hoffmann, A.

    The application of external fields provides a powerful tool to investigate a large variety of properties of excitons and exciton related processes. Within this chapter, we focus on the fundamental effects of static magnetic and strain fields on the optical properties of excitons in ZnO. The description is complemented by relevant examples. A general review of this topic can be found for constant fields in [Cho, Excitons, Topics in Current Physics, vol. 14 (Springer, Heidelberg, 1979)] and Hönerlage et al. [Phys. Rep. 124:161, 1985] and for modulation techniques in [Cardona, Modulation Spectroscopy (Academic, New York, 1969); Seraphin, Modulation Spectroscopy (North Holland, Amsterdam, 1973); Goldsmith, NATO Science Series II, Frontiers of Optical Spectroscopy, vol. 168 (Springer Netherlands, 2005)]. Not much has been published on the influence of static electric fields on excitons. A few references are given at the end of Sect. 8.2.

  14. Influences on assortative mating.

    PubMed

    Schmidt, H D; Glavce, C; Hartog, J

    1987-09-01

    Age plays a considerable role in assortative mating. As regards this criterion we can distinguish a "rural, more traditional model" with high values of the coefficients of correlation, and an "urban model" with significantly lower values. Concerning eye and hair colour we find both these models as well as transitional forms. In contrast to this there are no important differences in assortative mating between the rural and urban populations regarding the physical traits. Size of population and length of marriage can strongly influence the values of these correlations. They decrease as the size of the population decreases, in which a person chooses his/her partner. Increasing age of the couples also results in a decrease of these correlations.

  15. Developing Global Nurse Influencers.

    PubMed

    Spies, Lori A

    2016-01-01

    How can universities create engaged citizens and global leaders? Each year, a select group of advanced practice nursing students at Baylor University Louise Herrington School of Nursing travel to Africa for a month-long clinical mission experience. Students work alongside local and missionary healthcare providers in a comprehensive Christian outreach to the community at a high-volume clinic. Creating rich learning experiences in a global setting in significant and sustainable ways is difficult, but intentionally focusing on what we are called to do and who we serve provides ballast for faculty and students. The success of the trip in preparing students to be global influencers is evident by the work graduates elect to do around the world, following graduation.

  16. MEMS electrostatic influence machines

    NASA Astrophysics Data System (ADS)

    Phu Le, Cuong; Halvorsen, Einar

    2016-11-01

    This paper analyses the possibility of MEMS electrostatic influence machines using electromechanical switches like the historical predecessors did two centuries ago. We find that a generator design relying entirely on standard silicon-on-insulator(SOI) micromachining is conceivable and analyze its performance by simulations. The concept appears preferable over comparable diode circuits due to its higher maximum energy, faster charging and low precharging voltage. A full electromechanical lumped-model including parasitic capacitances of the switches is built to capture the dynamic of the generator. Simulation results show that the output voltage can be exponentially bootstrapped from a very low precharging voltage so that otherwise inadequately small voltage differences or charge imbalances can be made useful.

  17. Assessing Undue Influence.

    PubMed

    Plotkin, Daniel A; Spar, James E; Horwitz, Howard L

    2016-09-01

    A claim of undue influence (UI) often figures prominently in will and trust contests and in other legal matters. Mental health professionals (MHPs) are frequently asked to provide expert opinions on UI, but the task is challenging, because of the lack of a clear definition of UI, and conflicting and contradictory recommendations in the literature on the specific conduct of the MHP in rendering opinions on UI. Recently, however, a California statutory scheme on UI applicable in will, trust, conservatorship, and financial elder abuse cases was adopted, bringing greater clarity to the meaning of the construct. The clarification provides an opportunity to review the concern, and to recommend a set of principles to guide MHPs in the role of expert in such litigation. © 2016 American Academy of Psychiatry and the Law.

  18. TIPS geometry influences patency.

    PubMed

    Klasen-Sansone, J; Bode, J; Lanzman, R S; Kubitz, R; Immig, S; Heusch, P; Antoch, G; Häussinger, D; Blondin, D

    2015-01-01

    The purpose of this study was to evaluate potential causes of Transjugular intrahepatic portosystemic shunt (TIPS) dysfunction. We retrospectively evaluated 26 patients who required TIPS revision (group I) and 24 patients who did not require any further intervention (group II) within the first two years following TIPS implantation. The distance of the distal end of the stent to the hepatocaval junction was measured. Furthermore, the angle between the stent and the portal vein (inflow) and the angle between the stent and the hepatic vein (outflow) were measured. Furthermore, the following data were evaluated: pre- and postinterventional portal pressure gradients, maximal postinterventional flow and blood values [C-reactive protein (CRP), bilirubin, glutamic-oxaloacetic transaminase (GOT), glutamic-pyruvic transaminase (GPT)]. Compared with control subjects, patients who required TIPS revision showed a significantly longer distance from the distal end of the stent to the hepatocaval junction (I: 17.3 ± 10 mm, II: 6.7 ± 5.7 mm, p < 0.001). There was a statistically significant correlation between the above named distance and the time to revision (Pearson's correlation coefficient, r = 0.5, p = 0.01). In addition, patients with TIPS revision had a significantly larger angle of portalvenous inflow (alpha angle) than the control group (I: 100.5 ± 31.5°, II: 64.5 ± 31.6°, p < 0.001). Our results show that the distance from the end of the stent to the hepatocaval junction and the angle of portalvenous inflow are technical factors that may influence the shunt's patency rate. Of these two, the distance to the hepatocaval junction can be influenced easily by the interventionalist. © Georg Thieme Verlag KG Stuttgart · New York.

  19. Social Influence as Reinforcement Learning

    DTIC Science & Technology

    2016-01-13

    SECURITY CLASSIFICATION OF: This project examined a reinforcement learning model of conformity and social influence. Under this model, individuals...Oct-2015 Approved for Public Release; Distribution Unlimited Final Report: Social Influence as Reinforcement Learning The views, opinions and/or...Research Triangle Park, NC 27709-2211 W911NF-14-1-0001 - Final Report - Social Influence as Reinforcement Learning REPORT DOCUMENTATION PAGE 11. SPONSOR

  20. Genetic influences on sarcoidosis.

    PubMed

    Ishihara, M; Ohno, S

    1997-01-01

    To investigate the genetic influences underlying the development of sarcoidosis, HLA class II genotyping was performed in Japanese patients with sarcoidosis and healthy controls using the PCR-RFLP method. The frequencies of both DR52 group antigen-associated alleles (HLA-DRB1*11, -DRB1*12 and -DRB1*14) and DRB1*08 alleles were higher in the patient group, suggesting that the common, specific amino acid residue on the DRB1 molecule of these alleles may determine susceptibility to sarcoidosis. Alternatively, it is possible that another susceptibility gene, linked to these DRB1 alleles, exists within the MHC region. We screened the TNFA, TNFB, HSP70-1 and Hum70t genes around the class III region, as well as the HLA-DMA and -DMB genes in the class II region, for genetic polymorphism in sarcoidosis. None of these genes suggested a susceptibility to sarcoidosis. These studies support the thesis that one of the major genetic factors controlling the development of sarcoidosis is located within the DRB1 locus in the HLA class II region.

  1. Microstructural influences on the

    NASA Astrophysics Data System (ADS)

    Ramesh, K. T.; Coates, R. S.

    1992-09-01

    The influence of tungsten content, swaging, and grain size on the dynamic behavior of commercially available tungsten-nickel-iron (W-Ni-Fe) alloys has been examined using the compression Kolsky bar. The observed flow stresses increase with increasing tungsten content and with degree of swaging but are essentially independent of grain size for these compressive deformations. Further, the flow stresses sustained by these materials have a distinct dependence on strain rate, in that the flow stress increases by at least 20 pct over a range from 10-4 s-1 to 7 × 103 s-1. The rate sensitivity itself increases with increasing tungsten content. The rate sensitivity of the alloy with the highest tungsten content (97 pct W) appears to be essentially the same as that of pure polycrystalline tungsten. In addition to showing greater strain hardening, the unswaged alloy also shows a much higher rate dependence than the swaged alloys, with the flow stress almost doubling when the rate of deformation increases from quasistatic to 5 X 103 s-1. The rate-hardening mechanism within the composite appears to be essentially that as- sociated with the tungsten grains; however, the matrix contribution is significant in the case of an unswaged alloy.

  2. How experts gain influence.

    PubMed

    Mikes, Anette; Hall, Matthew; Millo, Yuval

    2013-01-01

    In theory, the risk management groups of two British banks--Saxon and Anglo--had the same influence in their organizations. But in practice, they did not: Saxon's was engaged in critical work throughout the bank, while Anglo's had little visibility outside its areas of expertise. In their study of these two financial institutions, the authors identified four competencies--trailblazing, toolmaking, teamwork, and translation--that help functional leaders or groups compete for top management's limited attention and increase their impact. Anglo's risk managers were strong in only some of the competencies, but Saxon's were strong in all four. They consistently scanned the internal and external environment for important issues to which they could apply a risk management perspective (trailblazing) and then developed tools--such as quarterly risk reports--that spread their expertise (toolmaking). While controlling the tools' design and implementation, the risk managers incorporated business managers' insights (teamwork) and made sure everyone could understand the findings (translation). Ultimately, experts' roles must fit the organization's strategy and structural needs. In some situations, functional experts can raise their profile by cultivating just two of the competencies. But those who are strong in all four are likely to be the most influential.

  3. Power, Influence Tactics, and Influence Processes in Virtual Teams

    ERIC Educational Resources Information Center

    Boughton, Marla

    2011-01-01

    Current studies of power, influence tactics, and influence processes in virtual teams assume that these constructs operate in a similar manner as they do in the face-to-face (FtF) environment. However, the virtual context differs from the FtF environment on a variety of dimensions, such as the availability of status cues. The differences between…

  4. Power, Influence Tactics, and Influence Processes in Virtual Teams

    ERIC Educational Resources Information Center

    Boughton, Marla

    2011-01-01

    Current studies of power, influence tactics, and influence processes in virtual teams assume that these constructs operate in a similar manner as they do in the face-to-face (FtF) environment. However, the virtual context differs from the FtF environment on a variety of dimensions, such as the availability of status cues. The differences between…

  5. Microbiologically Influenced Corrosion: an Update

    DTIC Science & Technology

    2014-01-01

    microbial/metal interactions. Microbiologically influenced corrosion, Sulphate reducing bacteria , Electrogenic bacteria , Electron acceptors, Microbial...Keywords: Microbiologically influenced corrosion, Sulphate reducing bacteria , Electrogenic bacteria , Electron acceptors, Microbial fuel cell Introduction...causative microorganisms are from all three main branches of evolutionary descent, i.e., bacteria , archaea (methanogens), and eukaryota (fungi

  6. Wetland Research Can Influence Policy

    EPA Science Inventory

    An objective of ecological research is to have a positive influence on the way natural resources are managed. The ability to influence policy with science depends on collaboration with the appropriate audience, identification of a relevant question, and awareness of the framewor...

  7. Text Signals Influence Team Artifacts

    ERIC Educational Resources Information Center

    Clariana, Roy B.; Rysavy, Monica D.; Taricani, Ellen

    2015-01-01

    This exploratory quasi-experimental investigation describes the influence of text signals on team visual map artifacts. In two course sections, four-member teams were given one of two print-based text passage versions on the course-related topic "Social influence in groups" downloaded from Wikipedia; this text had two paragraphs, each…

  8. Interdependent Sampling and Social Influence

    ERIC Educational Resources Information Center

    Denrell, Jerker; Le Mens, Gael

    2007-01-01

    Most explanations of social influence focus on why individuals might want to agree with the opinions or attitudes of others. The authors propose a different explanation that assumes the attitudes of others influence only the activities and objects individuals are exposed to. For example, individuals are likely to be exposed to activities that…

  9. Student Influence and Higher Education.

    ERIC Educational Resources Information Center

    Juola, Arvo E.

    Since 1965, student views and feelings have influenced great changes in higher education, sometimes to the detriment of long-term interests in academic institutions and colleges. One conspicuous recent trend is the desire of college students for more influence, impact, or power. Other prevalent attitudes may be characterized as a desire to be…

  10. Text Signals Influence Team Artifacts

    ERIC Educational Resources Information Center

    Clariana, Roy B.; Rysavy, Monica D.; Taricani, Ellen

    2015-01-01

    This exploratory quasi-experimental investigation describes the influence of text signals on team visual map artifacts. In two course sections, four-member teams were given one of two print-based text passage versions on the course-related topic "Social influence in groups" downloaded from Wikipedia; this text had two paragraphs, each…

  11. Lunar Influences on Human Aggression.

    ERIC Educational Resources Information Center

    Russell, Gordon W.; Dua, Manjula

    1983-01-01

    Used league records of all Canadian hockey games (N=426) played during a season to test a lunar-aggression hypothesis. Despite the use of multiple measures of lunar phase and interpersonal aggression, support for lunar influence was not forthcoming. Supplemental data revealed that beliefs in lunar influence are fairly common. (JAC)

  12. Student Influence and Higher Education.

    ERIC Educational Resources Information Center

    Juola, Arvo E.

    Since 1965, student views and feelings have influenced great changes in higher education, sometimes to the detriment of long-term interests in academic institutions and colleges. One conspicuous recent trend is the desire of college students for more influence, impact, or power. Other prevalent attitudes may be characterized as a desire to be…

  13. Wetland Research Can Influence Policy

    EPA Science Inventory

    An objective of ecological research is to have a positive influence on the way natural resources are managed. The ability to influence policy with science depends on collaboration with the appropriate audience, identification of a relevant question, and awareness of the framewor...

  14. Sibling influences on prosocial behavior.

    PubMed

    Hughes, Claire; McHarg, Gabrielle; White, Naomi

    2017-08-12

    Sibling relationships are characterized by familiarity and emotional intensity. Alongside frequent shared play, sibling interactions feature complementary interactions (e.g. teaching, caregiving) reflecting age-related asymmetries in socio-cognitive skills. These aspects may underpin sibling influences on prosocial behavior: theoretical accounts of social influences on prosocial behavior highlight emotion sharing, goal alignment, the intrinsically rewarding nature of social interaction, and scaffolding of social norms. Taking a fine-grained approach to prosocial behavior, we examine these processes in relation to sibling influences on children's comforting, sharing, and helping. Emergent themes include: developmental change in the nature of sibling influences on prosocial behavior, the need to consider sibling influences in the wider family context, and the importance of individual differences in the quality of sibling relationships. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Lunar Influences On Climate

    NASA Astrophysics Data System (ADS)

    Camuffo, Dario

    still open. In practice, lunar and solar influences can be found and have been demonstrated with more or less the same level of confidence. Both have the same order of magnitude, and are generally weak, interacting, and being often masked by local effects.

  16. Social influence: compliance and conformity.

    PubMed

    Cialdini, Robert B; Goldstein, Noah J

    2004-01-01

    This review covers recent developments in the social influence literature, focusing primarily on compliance and conformity research published between 1997 and 2002. The principles and processes underlying a target's susceptibility to outside influences are considered in light of three goals fundamental to rewarding human functioning. Specifically, targets are motivated to form accurate perceptions of reality and react accordingly, to develop and preserve meaningful social relationships, and to maintain a favorable self-concept. Consistent with the current movement in compliance and conformity research, this review emphasizes the ways in which these goals interact with external forces to engender social influence processes that are subtle, indirect, and outside of awareness.

  17. Normative social influence is underdetected.

    PubMed

    Nolan, Jessica M; Schultz, P Wesley; Cialdini, Robert B; Goldstein, Noah J; Griskevicius, Vladas

    2008-07-01

    The present research investigated the persuasive impact and detectability of normative social influence. The first study surveyed 810 Californians about energy conservation and found that descriptive normative beliefs were more predictive of behavior than were other relevant beliefs, even though respondents rated such norms as least important in their conservation decisions. Study 2, a field experiment, showed that normative social influence produced the greatest change in behavior compared to information highlighting other reasons to conserve, even though respondents rated the normative information as least motivating. Results show that normative messages can be a powerful lever of persuasion but that their influence is underdetected.

  18. Influence Analysis of Ranking Data.

    ERIC Educational Resources Information Center

    Poon, Wai-Yin; Chan, Wai

    2002-01-01

    Developed diagnostic measures to identify observations in Thurstonian models for ranking data that unduly influence parameter estimates obtained by the partition maximum likelihood approach of W. Chan and P. Bender (1998). (SLD)

  19. Influence Analysis of Ranking Data.

    ERIC Educational Resources Information Center

    Poon, Wai-Yin; Chan, Wai

    2002-01-01

    Developed diagnostic measures to identify observations in Thurstonian models for ranking data that unduly influence parameter estimates obtained by the partition maximum likelihood approach of W. Chan and P. Bender (1998). (SLD)

  20. How Technology Influences Interior Design.

    ERIC Educational Resources Information Center

    McDavitt, Tish

    1999-01-01

    Examines telecommunication technology's influences on interior school design and effective learning, and discusses how to implement this technology into the school. Building the infrastructure to support telecommunications in an educational setting and the importance of effective lighting are discussed. (GR)

  1. Influence of arthropods on ecosystems

    SciTech Connect

    Seastedt, T.R.; Crossley, D.A. Jr.

    1984-03-01

    Arthropod interactions with plants and microbes influence the amounts of living and dead organic matter and transfers of nutrients in terrestrial ecosystems. Arthropods in the canopy have their greatest effect on mobile elements such as potassium, whereas soil detritivores influence mineralization rates of less mobile elements such as nitrogen, phosphorus, and calcium. Nominal (baseline) herbivory and detritivory combine to speed nutrient cycling and reduce standing crops of decaying plant materials. 49 references, 1 figure, 3 tables.

  2. Tidal influence within Pennsylvanian sandstones

    SciTech Connect

    Archer, A.W. )

    1991-08-01

    Within Pennsylvanian-age strata of the Illinois basin, large-scale linear sand bodies have been previously interpreted as fluvial and deltaic in origin. Nonetheless, analyses of fine-scale sedimentology and bed forms within such sandstones and the associated shales indicate that tidal processes greatly influenced the depositional environments within such lithofacies. Recent work on Mid-Continent Pennsylvanian-age sandstones indicates the occurrence of similar depositional environments. Based upon the pervasive tidal influence observed within such strata, environmental analogs other than fluvial and deltaic bear consideration. In general, tidally influenced estuarine models seem particularly appropriate. Within such settings, the changeover from a fluvially dominated deposystem to tidally influenced estuary occurs during transgressive phases. Despite the tidal influence that can be interpreted from the sedimentology, the strata contain few, if any, marine indicators because of the low salinities that occurred during deposition. Ongoing work in the Mid-Continent indicates that Morrowan, Atokan, Desmoinesian, Missourian, and Virgilian sands share a number of similarities with the tidally influenced environments delineated in the Illinois basin studies. Thus a tidal/estuarine interpretation might be a generalizable model for many Pennsylvanian sandstones. In addition, enhanced understanding of the siliciclastic parts of Mid-Continent cyclothems provides a more useful framework for documentation of carbonate/siliciclastic interrelationships. Oscillations of carbonate/siliciclastic environments may be more readily explainable by climatic cycles rather than by traditionally popular depth-related facies models.

  3. Language may indeed influence thought.

    PubMed

    Zlatev, Jordan; Blomberg, Johan

    2015-01-01

    We discuss four interconnected issues that we believe have hindered investigations into how language may affect thinking. These have had a tendency to reappear in the debate concerning linguistic relativity over the past decades, despite numerous empirical findings. The first is the claim that it is impossible to disentangle language from thought, making the question concerning "influence" pointless. The second is the argument that it is impossible to disentangle language from culture in general, and from social interaction in particular, so it is impossible to attribute any differences in the thought patterns of the members of different cultures to language per se. The third issue is the objection that methodological and empirical problems defeat all but the most trivial version of the thesis of linguistic influence: that language gives new factual information. The fourth is the assumption that since language can potentially influence thought from "not at all" to "completely," the possible forms of linguistic influence can be placed on a cline, and competing theories can be seen as debating the actual position on this cline. We analyze these claims and show that the first three do not constitute in-principle objections against the validity of the project of investigating linguistic influence on thought, and that the last one is not the best way to frame the empirical challenges at hand. While we do not argue for any specific theory or mechanism for linguistic influence on thought, our discussion and the reviewed literature show that such influence is clearly possible, and hence in need of further investigations.

  4. Individual influence on model selection.

    PubMed

    Sterba, Sonya K; Pek, Jolynn

    2012-12-01

    Researchers in psychology are increasingly using model selection strategies to decide among competing models, rather than evaluating the fit of a given model in isolation. However, such interest in model selection outpaces an awareness that one or a few cases can have disproportionate impact on the model ranking. Though case influence on the fit of a single model in isolation has been often studied, case influence on model selection results is greatly underappreciated in psychology. This article introduces the issue of case influence on model selection and proposes 3 influence diagnostics for commonly used selection indices: the chi-square difference test, Bayesian information criterion, and Akaike's information criterion. These 3 diagnostics can be obtained simply from the byproducts of full information maximum likelihood estimation without heavy computational burden. We provide practical information on the interpretation and behavior of these diagnostics for applied researchers and provide software code to facilitate their use. Simulated and empirical examples involving different kinds of model comparison scenarios encountered in cross-sectional, longitudinal, and multilevel research as well as involving different kinds of outcome distributions illustrate the generality of the proposed diagnostics. An awareness of how cases influence model selection results is shown to aid researchers in understanding how representative their sample level results are at the case level.

  5. Genetic influences on adolescent behavior.

    PubMed

    Dick, Danielle M; Adkins, Amy E; Kuo, Sally I-Chun

    2016-11-01

    Adolescence is a transitional, developmental phase with marked shifts in behavior, particularly as related to risk-taking and experimentation. Genetic influences on adolescent behavior also show marked changes across this developmental period; in fact, adolescence showcases the dynamic nature of genetic influences on human behavior. Using the twin studies literature on alcohol use and misuse, we highlight several principles of genetic influence on adolescent behavior. We illustrate how genetic influences change (increase) across adolescence, as individuals have more freedom to express their predispositions and to shape their social worlds. We show how there are multiple genetic pathways to risk, and how the environment can moderate the importance of genetic predispositions. Finally, we review the literature aimed at identifying specific genes involved in adolescent behavior and understanding how identified genes impact adolescent outcomes. Ultimately, understanding how genetic predispositions combine with environmental influences to impact pathways of risk and resilience should be translated into improved prevention and intervention efforts; this remains a rich area for future research.

  6. Thinking aloud influences perceived time.

    PubMed

    Hertzum, Morten; Holmegaard, Kristin Due

    2015-02-01

    We investigate whether thinking aloud influences perceived time. Thinking aloud is widely used in usability evaluation, yet it is debated whether thinking aloud influences thought and behavior. If thinking aloud is restricted to the verbalization of information to which a person is already attending, there is evidence that thinking aloud does not influence thought and behavior. In an experiment, 16 thinking-aloud participants and 16 control participants solved a code-breaking task 24 times each. Participants estimated task duration. The 24 trials involved two levels of time constraint (timed, untimed) and resulted in two levels of success (solved, unsolved). The ratio of perceived time to clock time was lower for thinking-aloud than control participants. Participants overestimated time by an average of 47% (thinking aloud) and 94% (control). The effect of thinking aloud on time perception also held separately for timed, untimed, solved, and unsolved trials. Thinking aloud (verbalization at Levels 1 and 2) influences perceived time. Possible explanations of this effect include that thinking aloud may require attention, cause a processing shift that overshadows the perception of time, or increase mental workload. For usability evaluation, this study implies that time estimates made while thinking aloud cannot be compared with time estimates made while not thinking aloud, that ratings of systems experienced while thinking aloud may be inaccurate (because the experience of time influences other experiences), and that it may therefore be considered to replace concurrent thinking aloud with retrospective thinking aloud when evaluations involve time estimation.

  7. [Latin American malacology. Freshwater mollusks from Argentina].

    PubMed

    Rumi, Alejandra; Gregoric, Diego E Gutiérrez; Núñez, Verónica; Darrigran, Gustavo A

    2008-03-01

    . Species of sanitary interest are the propagators of: schistosomiasis -Biomphalaria peregrina, B. straminea y B. tenagophila, Planorbidae-, fasciolasis -Lymnaea viatrix and L. columnella, Lymnaeidae- and dermatitis -Chilina gibbosa and C. fluminea, Chilinidae. Invasive species are: Corbicula fluminea (Corbiculidae) and Limnoperna fortunei (Mytilidae). The construction of new areas for the protection and conservation of the high risk endemic species of freshwater molluscs is a priority. It is necessary to give special attention to the species of the patagonic mountain range and of the mesopotamic area of the Del Plata Basin.

  8. Greek influence on Babylonian astronomy?

    NASA Astrophysics Data System (ADS)

    Steele, J. M.

    Astronomy in Babylonia during the first millennium BC developed out of a long tradition of observing and interpreting the sky into a science that was both observational and theoretical. It is well established that these developments influenced the practice of astronomy in neighbouring cultures in the Indus valley, Egypt and the Greco-Roman world. However, it is less clear whether there was any significant input from foreign cultures into the development of Babylonian astronomy. In this paper I examine the evidence for possible traces of Greek influence on Babylonian astronomy during the late first millennium BC. In particular, I discuss two possible cases of Greek influence that have been proposed in recent years: the naming of certain zodiacal signs and a value for the length of the year found on a Babylonian text that may be based upon Greek observations of summer solstices.

  9. Executive control influences linguistic representations.

    PubMed

    Lev-Ari, Shiri; Keysar, Boaz

    2014-02-01

    Although it is known that words acquire their meanings partly from the contexts in which they are used, we proposed that the way in which words are processed can also influence their representation. We further propose that individual differences in the way that words are processed can consequently lead to individual differences in the way that they are represented. Specifically, we showed that executive control influences linguistic representations by influencing the coactivation of competing and reinforcing terms. Consequently, people with poorer executive control perceive the meanings of homonymous terms as being more similar to one another, and those of polysemous terms as being less similar to one another, than do people with better executive control. We also showed that bilinguals with poorer executive control experience greater cross-linguistic interference than do bilinguals with better executive control. These results have implications for theories of linguistic representation and language organization.

  10. Influence analysis of Github repositories.

    PubMed

    Hu, Yan; Zhang, Jun; Bai, Xiaomei; Yu, Shuo; Yang, Zhuo

    2016-01-01

    With the support of cloud computing techniques, social coding platforms have changed the style of software development. Github is now the most popular social coding platform and project hosting service. Software developers of various levels keep entering Github, and use Github to save their public and private software projects. The large amounts of software developers and software repositories on Github are posing new challenges to the world of software engineering. This paper tries to tackle one of the important problems: analyzing the importance and influence of Github repositories. We proposed a HITS based influence analysis on graphs that represent the star relationship between Github users and repositories. A weighted version of HITS is applied to the overall star graph, and generates a different set of top influential repositories other than the results from standard version of HITS algorithm. We also conduct the influential analysis on per-month star graph, and study the monthly influence ranking of top repositories.

  11. Antecedent influences on behavior disorders.

    PubMed Central

    Smith, R G; Iwata, B A

    1997-01-01

    The influence of antecedent events on behavior disorders has been relatively understudied by applied behavior analysts. This lack of research may be due to a focus on consequences as determinants of behavior and a historical disagreement on a conceptual framework for describing and interpreting antecedent variables. We suggest that antecedent influences can be described using terms derived from basic behavioral principles and that their functional properties can be adequately interpreted as discriminative and establishing operations. A set of studies on assessment and treatment of behavior disorders was selected for review based on their relevance to the topic of antecedent events. These studies were categorized as focusing on assessment of antecedent events, antecedent treatments for behavior disorders maintained by either positive or negative reinforcement, and special cases of antecedent events in behavior disorders. Some directions for future research on antecedent influences in the analysis and treatment of behavior disorders are discussed. PMID:9210312

  12. Language may indeed influence thought

    PubMed Central

    Zlatev, Jordan; Blomberg, Johan

    2015-01-01

    We discuss four interconnected issues that we believe have hindered investigations into how language may affect thinking. These have had a tendency to reappear in the debate concerning linguistic relativity over the past decades, despite numerous empirical findings. The first is the claim that it is impossible to disentangle language from thought, making the question concerning “influence” pointless. The second is the argument that it is impossible to disentangle language from culture in general, and from social interaction in particular, so it is impossible to attribute any differences in the thought patterns of the members of different cultures to language per se. The third issue is the objection that methodological and empirical problems defeat all but the most trivial version of the thesis of linguistic influence: that language gives new factual information. The fourth is the assumption that since language can potentially influence thought from “not at all” to “completely,” the possible forms of linguistic influence can be placed on a cline, and competing theories can be seen as debating the actual position on this cline. We analyze these claims and show that the first three do not constitute in-principle objections against the validity of the project of investigating linguistic influence on thought, and that the last one is not the best way to frame the empirical challenges at hand. While we do not argue for any specific theory or mechanism for linguistic influence on thought, our discussion and the reviewed literature show that such influence is clearly possible, and hence in need of further investigations. PMID:26582997

  13. The Anxiety of Influence and the Influence of Anxiety.

    ERIC Educational Resources Information Center

    Kountz, Carol

    A composition researcher collected stories from students with writing anxiety, using qualitative research tools of interview and interpretation. In literary theory it is not unusual to speak of anxiety of influence when referring to the torment of proving one is equal to a revered author. The critic Harold Bloom presented it as his theory of the…

  14. Advertising influences on young children's food choices and parental influence.

    PubMed

    Ferguson, Christopher J; Muñoz, Monica E; Medrano, Maria R

    2012-03-01

    To evaluate whether advertising for food influences choices made by children, the strength of these influences, and whether they might be easily undone by parental influences. Children between 3 and 8 years of age (n=75) were randomized to watch a series of programs with embedded commercials. Some children watched a commercial for a relatively healthy food item, the other children watched a commercial for a less healthy item, both from the same fast-food company. Children were also randomized either to receive parental encouragement to choose the healthy item or to choose whichever item they preferred. Results indicated that children were more likely to choose the advertised item, despite parental input. Parental input only slightly moderated this influence. Although advertising impact on children's food choices is moderate in size, it appears resilient to parental efforts to intervene. Food advertisements directed at children may have a small but meaningful effect on their healthy food choices. Copyright © 2012 Mosby, Inc. All rights reserved.

  15. Influencing the future of AGU

    NASA Astrophysics Data System (ADS)

    McPhaden, Michael; Finn, Carol; McEntee, Chris

    2012-01-01

    Steve Jobs, visionary cofounder of Apple, Inc., once said, “Everyone here has the sense that right now is one of those moments when we are influencing the future.” This statement aptly describes AGU at this time as the Board of Directors and the Council continue to influence the future in exciting ways by advancing our strategic plan (http://www.agu.org/about/mission.shtml). Both governing bodies held meetings in San Francisco immediately preceding the 2011 AGU Fall Meeting. The agendas for both meetings, along with the key outcomes, are posted on AGU's Web site (http://www.agu.org/about/governance/).

  16. Factors Influencing College Science Success

    ERIC Educational Resources Information Center

    Tai, Robert H.; Sadler, Philip M.; Mintzes, Joel J.

    2006-01-01

    In this paper, the authors report some of the salient findings of a large-scale, four-year national study, conducted at the Harvard-Smithsonian Center for Astrophysics, entitled "Factors Influencing College Science Success" (FICSS), which surveyed college students who enrolled in first-year biology, chemistry, and physics courses…

  17. Soft Factors Influence College Enrollment

    ERIC Educational Resources Information Center

    Fogg, Neeta P.; Harrington, Paul E.

    2010-01-01

    Evidence about the role that "soft factors" like student engagement and school environment play in influencing whether high school students go on to enroll in college is hard to come by. Over the past two years, the Center for Labor Market Studies (CLMS) of Northeastern University, with support from the Nellie Mae Education Foundation…

  18. Influences on Garifuna Youth's Education.

    ERIC Educational Resources Information Center

    Lewis, Karla

    This paper examines the influences on Garifuna (also known as Caribs) youth education through the voices of Garifuna educators and youths. The paper emphasizes, in both its content and methodology, that discussion of education in the Caribbean and specifically Belize cannot be separated from the educators' experiences and the adolescents'…

  19. Influence of convection on microstructure

    NASA Technical Reports Server (NTRS)

    Wilcox, William R.; Caram, Rubens; Mohanty, A. P.; Seth, Jayshree

    1990-01-01

    The mechanism responsible for the difference in microstructure caused by solidifying the MnBi-Bi eutectic in space is sought. The objectives for the three year period are as follows: (1) completion of the following theoretical analyses - determination of the influence of the Soret effect on the average solid composition versus distance of off-eutectic mixtures directionally solidified in the absence of convection, determination of the influence of convection on the microstructure of off-eutectic mixtures using a linear velocity profile in the adjacent melt, determination of the influence of volumetric changes during solidification on microconvection near the freezing interface and on microstructure, and determination of the influence of convection on microstructure when the MnBi fibers project out in front of the bismuth matrix; (2) search for patterns in the effect of microgravity on different eutectics (for example, eutectic composition, eutectic temperature, usual microstructure, densities of pure constituents, and density changes upon solidification); and (3) determination of the Soret coefficient and the diffusion coefficient for Mn-Bi melts near the eutectic composition, both through laboratory experiements to be performed here and from data from Shuttle experiments.

  20. The Influence of Marketing Education.

    ERIC Educational Resources Information Center

    Leventhal, Jerome I.

    2002-01-01

    A look at the history of marketing education shows how it has influenced the education of students and how its concepts are still being used in education today. Marketing educators were pioneers in educational opportunities for women, performance-based education, cooperative education, and leadership development. (JOW)

  1. Soft Factors Influence College Enrollment

    ERIC Educational Resources Information Center

    Fogg, Neeta P.; Harrington, Paul E.

    2010-01-01

    Evidence about the role that "soft factors" like student engagement and school environment play in influencing whether high school students go on to enroll in college is hard to come by. Over the past two years, the Center for Labor Market Studies (CLMS) of Northeastern University, with support from the Nellie Mae Education Foundation…

  2. Machiavellian Beliefs and Social Influence.

    ERIC Educational Resources Information Center

    O'Hair, Dan; Cody, Michael J.

    1987-01-01

    Replicates previous findings of separate Machiavellian belief constructs (Deceit, Flatter, Immorality, and Cynicism). Indicates that different constructs predict selection of compliance-gaining strategies; for example, actors who scored high on Immorality used more referent influence on superiors. Discusses implications of this study concerning a…

  3. Factors That Influence Teacher Attrition.

    ERIC Educational Resources Information Center

    Gonzalez, Patricia

    1995-01-01

    External, employment, and personal factors which influence teacher decisions to stay, leave, or transfer from teaching assignments are discussed, with emphasis on special education teachers. Factors attributed to teacher attrition in urban and rural environments also are briefly reviewed, along with attrition of related services professionals.…

  4. Surface Organization Influences Bistable Vision

    ERIC Educational Resources Information Center

    Graf, Erich W.; Adams, Wendy J.

    2008-01-01

    A priority for the visual system is to construct 3-dimensional surfaces from visual primitives. Information is combined across individual cues to form a robust representation of the external world. Here, it is shown that surface completion relying on multiple visual cues influences relative dominance during binocular rivalry. The shape of a…

  5. Family Influences on Early Development.

    ERIC Educational Resources Information Center

    Silber, Sharon

    1989-01-01

    The article reviews the literature concerning family influences on early childhood development. Implications of this literature for intervention planning with high risk children and families are suggested. Topics covered include the early parent-child relationship, disciplinary strategies, stimulation, parental instruction and expectations, the…

  6. Young Children's Influence in Preschool

    ERIC Educational Resources Information Center

    Emilson, Anette

    2007-01-01

    The purpose of this study was to investigate how very young children can influence their daily life in preschool, in relation to teacher control. The specific questions studied were: What opportunities do the children have to make their own choices and take the initiative? How does teacher control manifest itself? What form do permanent…

  7. Phonological Awareness: Factors of Influence

    ERIC Educational Resources Information Center

    Frohlich, Linda Paulina; Petermann, Franz; Metz, Dorothee

    2013-01-01

    Early child development is influenced by various genetic and environmental factors. This study aims to identify factors that affect the phonological awareness of preschool and first grade children. Based on a sample of 330 German-speaking children (mean age = 6.2 years) the following domains were evaluated: Parent factors, birth and pregnancy,…

  8. Surface Organization Influences Bistable Vision

    ERIC Educational Resources Information Center

    Graf, Erich W.; Adams, Wendy J.

    2008-01-01

    A priority for the visual system is to construct 3-dimensional surfaces from visual primitives. Information is combined across individual cues to form a robust representation of the external world. Here, it is shown that surface completion relying on multiple visual cues influences relative dominance during binocular rivalry. The shape of a…

  9. Phonological Awareness: Factors of Influence

    ERIC Educational Resources Information Center

    Frohlich, Linda Paulina; Petermann, Franz; Metz, Dorothee

    2013-01-01

    Early child development is influenced by various genetic and environmental factors. This study aims to identify factors that affect the phonological awareness of preschool and first grade children. Based on a sample of 330 German-speaking children (mean age = 6.2 years) the following domains were evaluated: Parent factors, birth and pregnancy,…

  10. Factors Influencing College Science Success

    ERIC Educational Resources Information Center

    Tai, Robert H.; Sadler, Philip M.; Mintzes, Joel J.

    2006-01-01

    In this paper, the authors report some of the salient findings of a large-scale, four-year national study, conducted at the Harvard-Smithsonian Center for Astrophysics, entitled "Factors Influencing College Science Success" (FICSS), which surveyed college students who enrolled in first-year biology, chemistry, and physics courses…

  11. Soil Wetness Influences Log Skidding

    Treesearch

    William N. Darwin

    1960-01-01

    One of the least explored variables in timber harvesting is the effect of ground conditions on log production . The Southern Hardwoods Laboratory is studying this variable and its influence on performance of skidding vehicles in Southern bottom lands. The test reported here was designed to evaluate the effects of bark features on skidding coefficients, but it also...

  12. Factors influencing children's food choice.

    PubMed

    Hursti, Ulla-Kaisa Koivisto

    1999-01-01

    Although food habits arc not stable and unchanging during a person's lifetime, a base for healthy food habits can be created in early childhood. Children's food habits can be assumed to be influenced by their parents' food habits and choices. The aim of this article is to review factors influencing food choice in children as well as in adults. The results demonstrate that the development of children's food habits is influenced by a multitude of factors. Parents play an important role in the formation of food habits and preferences of young children. They can influence their children's food choice by making specific foods available, by acting as models for their children and by their behaviour in specific situations. Children tend to be afraid of new foods and do not readily accept them. However, experience is known to enhance preference, and earlier experiences of a particular food are the major determinants of the development of children's food acceptance patterns. Thus, parents should be encouraged to make healthy foods easily available to the child and serve these foods in positive mealtime situations in order to help their child to develop healthy food habits.

  13. Factors influencing children's food choice.

    PubMed

    Koivisto Hursti, U K

    1999-04-01

    Although food habits are not stable and unchanging during a person's lifetime, a base for healthy food habits can be created in early childhood. Children's food habits can be assumed to be influenced by their parents' food habits and choices. The aim of this article is to review factors influencing food choice in children as well as in adults. The results demonstrate that the development of children's food habits is influenced by a multitude of factors. Parents play an important role in the formation of food habits and preferences of young children. They can influence their children's food choice by making specific foods available, by acting as models for their children and by their behaviour in specific situations. Children tend to be afraid of new foods and do not readily accept them. However, experience is known to enhance preference, and earlier experiences of a particular food are the major determinants of the development of children's food acceptance patterns. Thus, parents should be encouraged to make healthy foods easily available to the child and serve these foods in positive mealtime situations in order to help their child to develop healthy food habits.

  14. Individual Influence on Model Selection

    ERIC Educational Resources Information Center

    Sterba, Sonya K.; Pek, Jolynn

    2012-01-01

    Researchers in psychology are increasingly using model selection strategies to decide among competing models, rather than evaluating the fit of a given model in isolation. However, such interest in model selection outpaces an awareness that one or a few cases can have disproportionate impact on the model ranking. Though case influence on the fit…

  15. Influences on Adolescents' Vocational Development.

    ERIC Educational Resources Information Center

    Mortimer, Jeylan T.; And Others

    A study charted family, school, workplace, and community experiences that are relevant to the vocational development of high school students, focusing on five areas of influence: allowance practices within the family, economic status, paid work experience, volunteerism, and gender differences. The data were from the "Youth Development…

  16. Intelligence: Genetic and Environmental Influences.

    ERIC Educational Resources Information Center

    Cancro, Robert, Ed.

    This book on the genetic and environmental influences on intelligence is comprised of the following papers: "The Structure of Intelligence in Relation to the Nature-Nurture Controversy," R. B. Cattell; "Theory of Intelligence," L. G. Humphreys; "Using Measured Intelligence Intelligently," P. R. Merrifield; "Intelligence: Definition, Theory, and…

  17. Cultural Influences on Technical Manuals.

    ERIC Educational Resources Information Center

    Warren, Thomas L.

    2002-01-01

    Discusses the cultural elements in developing a technical manual. Shows, through a comparison of two mythical cultures, how the manual will differ when organized for those two cultures. Considers the influences of culture on developing technical documents, specifically manuals. Concludes that the attitudes of a culture are significant factors in…

  18. Influence

    NASA Astrophysics Data System (ADS)

    Jassim, Salah Abdul-Jabbar; Zumaila, Abubaker A. Rashid Ali; Al Waly, Gassan Abdella Ali

    CdS thin films were deposited onto glass substrates at three different temperatures (20, 100 and 200 °C) by vacuum thermal evaporation at 10-5 Torr using pure crystal as evaporated targets. The effects of substrate temperature on structural, electrical and optical properties were studied. Structural analysis using X-ray diffraction (XRD) and scanning electronic microscope (SEM) revealed that the films are polycrystalline in nature with a hexagonal wurtzite structure having (0 0 2) plane as the preferred orientation. The crystalline size (D), dislocation density (δ), strain (ε) and texture coefficient TC(hkl) were calculated. All the films have high optical transmittance (>80%) in the visible range. The optical band gap values are found to be in the range of (2.3-2.43 eV) and found to decrease with increase in substrate temperature. DC electrical conductivity was carried out at room temperature indicating a very low electrical conductivity.

  19. Bacterial Influences on Animal Origins

    PubMed Central

    Alegado, Rosanna A.; King, Nicole

    2014-01-01

    Animals evolved in seas teeming with bacteria, yet the influences of bacteria on animal origins are poorly understood. Comparisons among modern animals and their closest living relatives, the choanoflagellates, suggest that the first animals used flagellated collar cells to capture bacterial prey. The cell biology of prey capture, such as cell adhesion between predator and prey, involves mechanisms that may have been co-opted to mediate intercellular interactions during the evolution of animal multicellularity. Moreover, a history of bacterivory may have influenced the evolution of animal genomes by driving the evolution of genetic pathways for immunity and facilitating lateral gene transfer. Understanding the interactions between bacteria and the progenitors of animals may help to explain the myriad ways in which bacteria shape the biology of modern animals, including ourselves. PMID:25280764

  20. Factors influencing susceptibility to metals.

    PubMed Central

    Gochfeld, M

    1997-01-01

    Although the long-neglected field of human susceptibility to environmental toxicants is currently receiving renewed attention, there is only scant literature on factors influencing susceptibility to heavy metals. Genetic factors may influence the availability of sulfhydryl-containing compounds such as glutathione and metallothionein, which modify the distribution and toxicity of certain metals. Age and gender play a role in modifying uptake and distribution, although the mechanisms are often obscure. Concurrent exposure to divalent cations may enhance or reduce the toxicity of certain metals through competition for receptor-mediated transport or targets. Increasing use of biomarkers of exposure should greatly increase our understanding of the underlying distribution of susceptibility to various environmental agents. PMID:9255566

  1. Informational influences on physician referrals.

    PubMed

    Beltramini, R F; Sirsi, A K

    1992-01-01

    Today's health care marketers are devoting significant resources to increase physician referrals, an area vital to their continued survival. The goal of this investigation was to integrate the findings of previous research on physician referrals, and to provide an up-to-date assessment of those influences underlying physician referral behavior. A questionnaire was mailed to 1,800 physicians differing in specialty and years in practice. Three informational influences were found to affect physician referrals: Program Information, Patient Input, and Location. The results suggest a need for specialists and other organizations interested in managing physician referrals to (a) establish and maintain a network of relationships among those physicians referring patients and specialists being referred to through personal communication, (b) maintain a pool of knowledgeable professionals willing to supply relevant and current information to physicians, and (c) provide complete and prompt feedback information to the referring physician. Managerial implications and directions for future research are also discussed.

  2. Factors influencing pacing in triathlon

    PubMed Central

    Wu, Sam SX; Peiffer, Jeremiah J; Brisswalter, Jeanick; Nosaka, Kazunori; Abbiss, Chris R

    2014-01-01

    Triathlon is a multisport event consisting of sequential swim, cycle, and run disciplines performed over a variety of distances. This complex and unique sport requires athletes to appropriately distribute their speed or energy expenditure (ie, pacing) within each discipline as well as over the entire event. As with most physical activity, the regulation of pacing in triathlon may be influenced by a multitude of intrinsic and extrinsic factors. The majority of current research focuses mainly on the Olympic distance, whilst much less literature is available on other triathlon distances such as the sprint, half-Ironman, and Ironman distances. Furthermore, little is understood regarding the specific physiological, environmental, and interdisciplinary effects on pacing. Therefore, this article discusses the pacing strategies observed in triathlon across different distances, and elucidates the possible factors influencing pacing within the three specific disciplines of a triathlon. PMID:25258562

  3. Factors influencing pacing in triathlon.

    PubMed

    Wu, Sam Sx; Peiffer, Jeremiah J; Brisswalter, Jeanick; Nosaka, Kazunori; Abbiss, Chris R

    2014-01-01

    Triathlon is a multisport event consisting of sequential swim, cycle, and run disciplines performed over a variety of distances. This complex and unique sport requires athletes to appropriately distribute their speed or energy expenditure (ie, pacing) within each discipline as well as over the entire event. As with most physical activity, the regulation of pacing in triathlon may be influenced by a multitude of intrinsic and extrinsic factors. The majority of current research focuses mainly on the Olympic distance, whilst much less literature is available on other triathlon distances such as the sprint, half-Ironman, and Ironman distances. Furthermore, little is understood regarding the specific physiological, environmental, and interdisciplinary effects on pacing. Therefore, this article discusses the pacing strategies observed in triathlon across different distances, and elucidates the possible factors influencing pacing within the three specific disciplines of a triathlon.

  4. The influence of Peter Ladefoged

    NASA Astrophysics Data System (ADS)

    Stevens, Kenneth N.

    2005-09-01

    The research and publications of Peter Ladefoged and his students have been a strong influence in elevating the field of phonetics to a science, and in bringing together phonetics and phonology. I will cite some examples of how Peter's work and that of his colleagues has influenced the research of many of us at MIT and around the world, where attempts to develop unifying theories often need to undergo continuous revision based on the meticulous articulatory and acoustic data that he reports in his books and other publications. These include his descriptions of the involvement of the tongue root in vowel systems, the fricatives of Mandarin Chinese, the inventory of places of articulation he catalogs in the languages of the world, and the many uses of laryngeal states in providing phonological contrasts. [Supported in part by grants from NIDCD.

  5. Reynolds number influences in aeronautics

    NASA Technical Reports Server (NTRS)

    Bushnell, Dennis M.; Yip, Long P.; Yao, Chung-Sheng; Lin, John C.; Lawing, Pierce L.; Batina, John T.; Hardin, Jay C.; Horvath, Thomas J.; Fenbert, James W.; Domack, Christopher S.

    1993-01-01

    Reynolds number, a measure of the ratio of inertia to viscous forces, is a fundamental similarity parameter for fluid flows and therefore, would be expected to have a major influence in aerodynamics and aeronautics. Reynolds number influences are generally large, but monatomic, for attached laminar (continuum) flow; however, laminar flows are easily separated, inducing even stronger, non-monatomic, Reynolds number sensitivities. Probably the strongest Reynolds number influences occur in connection with transitional flow behavior. Transition can take place over a tremendous Reynolds number range, from the order of 20 x 10(exp 3) for 2-D free shear layers up to the order of 100 x 10(exp 6) for hypersonic boundary layers. This variability in transition behavior is especially important for complex configurations where various vehicle and flow field elements can undergo transition at various Reynolds numbers, causing often surprising changes in aerodynamics characteristics over wide ranges in Reynolds number. This is further compounded by the vast parameterization associated with transition, in that any parameter which influences mean viscous flow development (e.g., pressure gradient, flow curvature, wall temperature, Mach number, sweep, roughness, flow chemistry, shock interactions, etc.), and incident disturbance fields (acoustics, vorticity, particulates, temperature spottiness, even electro static discharges) can alter transition locations to first order. The usual method of dealing with the transition problem is to trip the flow in the generally lower Reynolds number wind tunnel to simulate the flight turbulent behavior. However, this is not wholly satisfactory as it results in incorrectly scaled viscous region thicknesses and cannot be utilized at all for applications such as turbine blades and helicopter rotors, nacelles, leading edge and nose regions, and High Altitude Long Endurance and hypersonic airbreathers where the transitional flow is an innately critical

  6. Influence of convection on microstructure

    NASA Technical Reports Server (NTRS)

    Wilcox, William R.; Regel, Liya L.

    1994-01-01

    The primary motivation for this research was to determine the cause for space processing altering the microstructure of some eutectics, especially the MnBi-Bi eutectic. Four primary hypotheses were to be tested under this current grant: (1) A fibrous microstructure is much more sensitive to convection than a lamellar microstructure, which was assumed in our prior theoretical treatment. (2) An interface with one phase projecting out into the melt is much more sensitive to convection than a planar interface, which was assumed in our prior theoretical treatment. (3) The Soret effect is much more important in the absence of convection and has a sufficiently large influence on microstructure that its action can explain the flight results. (4) The microstructure is much more sensitive to convection when the composition of the bulk melt is off eutectic. These hypotheses were tested. It was concluded that none of these can explain the Grumman flight results. Experiments also were performed on the influence of current pulses on MnBi-Bi microstructure. A thorough review was made of all experimental results on the influence of convection on the fiber spacing in rod eutectics, including results from solidification in space or at high gravity, and use of mechanical stirring or a magnetic field. Contradictory results were noted. The predictions of models for convective influences were compared with the experimental results. Vigorous mechanical stirring appears to coarsen the microstructure by altering the concentration field in front of the freezing interface. Gentle convection is believed to alter the microstructure of a fibrous eutectic only when it causes a fluctuating freezing rate with a system for which the kinetics of fiber branching differs from that for fiber termination. These fluctuations may cause the microstructure to coarsen or to become finer, depending on the relative kinetics of these processes. The microstructure of lamellar eutectics is less sensitive to

  7. Executive presence for strategic influence.

    PubMed

    Shirey, Maria R

    2013-01-01

    This department highlights change management strategies that may be successful in strategically planning and executing organizational change initiatives. With the goal of presenting practical approaches helpful to nurse leaders advancing organizational change, content includes evidence-based projects, tools, and resources that mobilize and sustain organizational change initiatives. In this article, the author discusses cultivating executive presence, a crucial component of great leadership, needed for strategic influence and to drive change.

  8. Government influence on patient organizations.

    PubMed

    Van de Bovenkamp, Hester M; Trappenburg, Margo J

    2011-12-01

    Patient organizations increasingly play an important role in health care decision-making in Western countries. The Netherlands is one of the countries where this trend has gone furthest. In the literature some problems are identified, such as instrumental use of patient organizations by care providers, health insurers and the pharmaceutical industry. To strengthen the position of patient organizations government funding is often recommended as a solution. In this paper we analyze the ties between Dutch government and Dutch patient organizations to learn more about the effects of such a relationship between government and this part of civil society. Our study is based on official government documents and existing empirical research on patient organizations. We found that government influence on patient organizations has become quite substantial with government influencing the organizational structure of patient organizations, the activities these organizations perform and even their ideology. Financing patient organizations offers the government an important means to hold them accountable. Although the ties between patient organizations and the government enable the former to play a role that can be valued as positive by both parties, we argue that they raise problems as well which warrant a discussion on how much government influence on civil society is acceptable.

  9. Benchmarking Measures of Network Influence

    NASA Astrophysics Data System (ADS)

    Bramson, Aaron; Vandermarliere, Benjamin

    2016-09-01

    Identifying key agents for the transmission of diseases (ideas, technology, etc.) across social networks has predominantly relied on measures of centrality on a static base network or a temporally flattened graph of agent interactions. Various measures have been proposed as the best trackers of influence, such as degree centrality, betweenness, and k-shell, depending on the structure of the connectivity. We consider SIR and SIS propagation dynamics on a temporally-extruded network of observed interactions and measure the conditional marginal spread as the change in the magnitude of the infection given the removal of each agent at each time: its temporal knockout (TKO) score. We argue that this TKO score is an effective benchmark measure for evaluating the accuracy of other, often more practical, measures of influence. We find that none of the network measures applied to the induced flat graphs are accurate predictors of network propagation influence on the systems studied; however, temporal networks and the TKO measure provide the requisite targets for the search for effective predictive measures.

  10. Benchmarking Measures of Network Influence

    PubMed Central

    Bramson, Aaron; Vandermarliere, Benjamin

    2016-01-01

    Identifying key agents for the transmission of diseases (ideas, technology, etc.) across social networks has predominantly relied on measures of centrality on a static base network or a temporally flattened graph of agent interactions. Various measures have been proposed as the best trackers of influence, such as degree centrality, betweenness, and k-shell, depending on the structure of the connectivity. We consider SIR and SIS propagation dynamics on a temporally-extruded network of observed interactions and measure the conditional marginal spread as the change in the magnitude of the infection given the removal of each agent at each time: its temporal knockout (TKO) score. We argue that this TKO score is an effective benchmark measure for evaluating the accuracy of other, often more practical, measures of influence. We find that none of the network measures applied to the induced flat graphs are accurate predictors of network propagation influence on the systems studied; however, temporal networks and the TKO measure provide the requisite targets for the search for effective predictive measures. PMID:27670635

  11. Genetic influences on social cognition.

    PubMed

    Skuse, David H; Gallagher, Louise

    2011-05-01

    Human social behavior develops under the influence of genetic, environmental, and cultural factors. Social cognition comprises our ability to understand and respond appropriately to other people's social approaches or responses. The concept embraces self-knowledge and theory of mind, or the ability to think about emotions and behavior from the perspective of another person. The neuropeptides oxytocin (OT) and vasopressin (AVP) are now known to play an important role, affecting individual differences in parenting behavior, social recognition, and affiliative behaviors. The processes of social cognition are also supported by reward circuitry, underpinned by the dopaminergic neurotransmitter system. Reward processes build social relationships, in parenting and pair-bonding, and influence social interactions that require trust, or display altruism. The impact of emotional regulation upon social behavior, including mood and anxiety, is also mediated through the serotonergic system. Variation in activity of serotonergic networks in the brain influences emotional responsivity, including subjective feelings, physiological responses, emotional expressions, and the tendency to become engaged in action as a consequence of a feeling state. Genetic variation in the receptors associated with OT, AVP, dopamine, and serotonin has been intensively studied in humans and animal models. Recent findings are building an increasingly coherent picture of regulatory mechanisms.

  12. Mercury bioaccumulation along food webs in temperate aquatic ecosystems colonized by aquatic macrophytes in south western France.

    PubMed

    Gentès, Sophie; Maury-Brachet, Régine; Guyoneaud, Rémy; Monperrus, Mathilde; André, Jean-Marc; Davail, Stéphane; Legeay, Alexia

    2013-05-01

    Mercury (Hg) is considered as an important pollutant for aquatic systems as its organic form, methylmercury (MeHg), is easily bioaccumulated and bioamplified along food webs. In various ecosystems, aquatic periphyton associated with macrophyte was identified as an important place for Hg storage and methylation by microorganisms. Our study concerns temperate aquatic ecosystems (South Western France) colonized by invasive macrophytes and characterized by high mercury methylation potentials. This work establishes original data concerning Hg bioaccumulation in organisms (plants, crustaceans, molluscs and fish) from five contrasting ecosystems. For low trophic level species, total Hg (THg) concentrations were low (from 27±2ngTHgg(-1)dw in asiatic clam Corbicula fluminea to 418±114ngTHgg(-1)dw in crayfish Procambarus clarkii). THg concentrations in some carnivorous fish (high trophic level) were close to or exceeded the International Marketing Level (IML) with values ranging from 1049±220ngTHgg(-1)dw in pike perch muscle (Sander lucioperca) to 3910±1307ngTHgg(-1)dw in eel muscle (Anguilla Anguilla). Trophic levels for the individuals were also evaluated through stable isotope analysis, and linked to Hg concentrations of organisms. A significant Hg biomagnification (r(2)= 0.9) was observed in the Aureilhan lake, despite the absence of top predator fish. For this site, Ludwigia sp. periphyton, as an entry point of Hg into food webs, is a serious hypothesis which remains to be confirmed. This study provides a first investigation of Hg transfer in the ecosystems of south western France and allows the assessment of the risk associated with the presence of Hg in aquatic food webs.

  13. The use of a Weight-of-Evidence approach to address sediment quality in the Odiel River basin (SW, Spain).

    PubMed

    Bonnail, Estefanía; Sarmiento, Aguasanta M; DelValls, T Ángel

    2016-11-01

    The fluvial systems of the Iberian Pyrite Belt (SW Iberian Peninsula) are affected by acid mine drainage (a lixiviate residue product of mining activities derived from sulfide oxidation). The high acidity and high concentrations of sulfates and metal(loid)s are the main causes of the environmental degradation of the Odiel River basin. The use of weight of evidence approach in areas of the Odiel River basin implies the integration of different lines of evidence (chemistry, toxicity and bioaccumulation) using the freshwater clam Corbicula fluminea as target species. The integration of the results from the application of the different lines of evidence showed that the index of pollution was higher downvalley (Ptriad=12,312), moderate after mining effluent discharges (Ptriad=13.9) and very low where the Odiel River sources (Ptriad=6.31). The multivariate analysis indicated that variables and chemicals were associated with geochemical matrix and background levels (% of fines and toxic metal(loid) concentrations), toxic effects, and metal(loid) bioaccumulation reflecting the geographical distribution of the contamination towards the estuary. Metal(loid) thresholds were calculated for the study area as site-specific values of interim freshwater sediment quality values: As≥171; Cd≥0.48; Co≥8.82; Cr≥38.4; Cu≥451; Ni≥18.4; Pb≥377; Sb≥17.7; Zn≥221mg/kg of freshwater fluvial dry sediment. These results revealed the possibility of using the TEL values proposed by the USEPA and the NOAA for sediments from this site, and proposed lower PEL values for the Iberian Pyrite Belt as result of toxicity effects found in the Asian clam due to the combination of extreme acidity and high metal(loid) concentrations.

  14. Trace elements and organic compounds in streambed sediment and aquatic biota from the Sacramento River Basin, California, October and November 1995

    USGS Publications Warehouse

    MacCoy, Dorene E.; Domagalski, Joseph L.

    1999-01-01

    Elevated levels of trace elements and hydrophobic organic compounds were detected in streambed sediments and aquatic biota [Asiatic clam (Corbicula fluminea) or bottom-feeding fish] of the Sacramento River Basin, California, during October and November 1995. Trace elements detected included cadmium, copper, mercury, lead, and zinc. Elevated levels of cadmium, copper, and zinc in the upper Sacramento River are attributed to a mining land use, and elevated levels of zinc and lead in an urban stream, and possibly in the lower Sacramento River, are attributed to urban runoff processes. Elevated levels of mercury in streambed sediment are attributed to either past mercury mining or to the use of mercury in past gold mining operations. Mercury mining was an important land use within the Coast Ranges in the past and gold mining was an important land use of the Sierra Nevada in the past. Mercury was the only trace element found in elevated levels in the tissue of aquatic biota, and those levels also could be attributed to either mining or urban runoff. Hydrophobic organic compounds also were detected in streambed sediments and aquatic biota. The most frequently detected compounds were DDT and its breakdown products, dieldrin, oxychlordane, and toxaphene. Differences were found in the types of compounds detected at agricultural sites and the urban site. Although both types of sites had measurable concentrations of DDT or its breakdown products, the urban site also had measurable concentrations of pesticides used for household pest control. Few semivolatile compounds were detected in the streambed sediments of any site. The semivolatile compound p-cresol, a coal-tar derivative associated with road maintenance, was found in the highest concentration.

  15. Chemosensitizers of the multixenobiotic resistance in amorphous aggregates (marine snow): etiology of mass killing on the benthos in the Northern Adriatic?

    PubMed

    Müller, W E; Riemer, S; Kurelec, B; Smodlaka, N; Puskaric, S; Jagic, B; Müller-Niklas, G; Queric, N V

    1998-12-01

    Periodically appearing amorphous aggregates, `marine snow', are formed in the sea and if settled as mats on the sea bottom cause death of benthic metazoans. Especially those animals are killed which are sessile filter feeders, e.g. sponges, mussels, or Anthozoa. The etiology of the toxic principle(s) is not yet well understood. Gel-like marine snow aggregates occurred in the Northern Adriatic during summer 1997. Samples of these aggregates were collected during the period July to September and the outer as well as the inner zones were analyzed for (i) cell toxicity, and (ii) chemosensitizing activity of the multixenobiotic resistance (MXR) mechanism. Organic extracts were prepared and cell toxicity was determined using mouse lymphoma cells. The experiments revealed that the major activity is seen in the center of the mats of the gel-like aggregates; a growth inhibitory activity of up to 54% (correlated to 5 ml of snow sample) was determined. The same extracts were used to determine the inhibition of the P-glycoprotein (Pgp) extrusion pump which confers the multixenobiotic resistance. The analyses were performed with cells from the sponge Suberites domuncula and with gills from the clam Corbicula fluminea in situ. Both systems have been shown to express the Pgp extrusion pump. The data show that extracts from the outer zone of the gel-like aggregate samples display pronounced inhibitory activity on the MXR extrusion pump and hence act as chemosensitizers by reversing the MXP property. These findings indicate that gel-like aggregates contain compounds in the outer zone, chemosensitizer of the Pgp extrusion pump, which lower the level of protection of metazoan animals towards dissolved compounds in their surrounding milieu, and in the center toxic compounds which are-very likely-even in the absence of chemosensitizers hazardous for the invertebrates.

  16. Microplastics in Taihu Lake, China.

    PubMed

    Su, Lei; Xue, Yingang; Li, Lingyun; Yang, Dongqi; Kolandhasamy, Prabhu; Li, Daoji; Shi, Huahong

    2016-09-01

    In comparison with marine environments, the occurrence of microplastics in freshwater environments is less understood. In the present study, we investigated microplastic pollution levels during 2015 in Taihu Lake, the third largest Chinese lake located in one of the most developed areas of China. The abundance of microplastics reached 0.01 × 10(6)-6.8 × 10(6) items/km(2) in plankton net samples, 3.4-25.8 items/L in surface water, 11.0-234.6 items/kg dw in sediments and 0.2-12.5 items/g ww in Asian clams (Corbicula fluminea). The average abundance of microplastics was the highest in plankton net samples from the southeast area of the lake and in the sediments from the northwest area of the lake. The northwest area of the lake was the most heavily contaminated area of the lake, as indicated by chlorophyll-α and total phosphorus. The microplastics were dominated by fiber, 100-1000 μm in size and cellophane in composition. To our best knowledge, the microplastic levels measured in plankton net samples collected from Taihu Lake were the highest found in freshwater lakes worldwide. The ratio of the microplastics in clams to each sediment sample ranged from 38 to 3810 and was negatively correlated to the microplastic level in sediments. In brief, our results strongly suggest that high levels of microplastics occurred not only in water but also in organisms in Taihu Lake.

  17. Effects of deposit-feeding tubificid worms and filter-feeding bivalves on benthic-pelagic coupling: implications for the restoration of eutrophic shallow lakes.

    PubMed

    Zhang, Xiufeng; Liu, Zhengwen; Jeppesen, Erik; Taylor, William D

    2014-03-01

    Benthic-pelagic coupling is a key factor in the dynamics of shallow lakes. A 12-week mesocosm experiment tested the hypothesis that deposit-feeding tubificid worms stimulate the growth of pelagic algae while filter-feeding bivalves promote the growth of benthic algae, using the deposit-feeding tubificid Limnodrilus hoffmeisteri and the filter-feeding bivalve Anodonta woodiana. A tube-microcosm experiment using a (32)P radiotracer tested for differential effects of tubificids and bivalves on the release of sediment phosphorus (P). In this experiment A. woodiana was replaced by Corbicula fluminea, a smaller bivalve from the same functional group whose size was more appropriate to the experimental tubes needed for the tracer study. The first experiment recorded greater nutrient concentrations in the overlying water, higher biomass of pelagic algae as measured by chlorophyll a (Chl a), lower light intensity at the sediment and lower biomass of benthic algae in the worm treatments than in the controls, while nutrients and Chl a of pelagic algae were lower and the light intensity and Chl a of benthic algae were higher in the bivalve treatments than in the controls. In the second experiment, (32)P activity in the overlying water was higher in both treatments than in the controls, but highest in the worm treatment indicating that both animals accelerated P release from the sediment, with the biggest effect associated with the presence of worms. Our study demonstrates that worms promote pelagic algal growth by enhancing the release of sediment nutrients, while bivalves, likely through their grazing on pelagic algae increasing available light levels, stimulate benthic algal growth despite enhanced P release from the sediment and thus aid the establishment of clear water states. The rehabilitation of native bivalve populations may therefore enhance the recovery of eutrophic shallow lakes. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. Chlordane, DDT, PCB's, and other selected organic compounds in Asiatic clams and yellow bullhead in the Potomac River Basin, 1992

    USGS Publications Warehouse

    Zappia, Humbert

    1996-01-01

    Chlordane, DDT (dichlor-diphenyl-trichloroethane), and PCB's (polychlorinated biphenyls) were the most widespread organic contaminants detected during a 1992 survey of aquatic biological tissues in the Potomac River Basin. On the basis of existing U.S. Food and Drug Administration criteria, no new threats to human health were discovered, although chlordane concentrations may pose a threat to fish-eating wildlife. Chlordane exceeded the National Academy of Science and National Academy of Engineering recommended maximum concentration for the protection of fish-eating wildlife at two sites. The survey, conducted by the U.S. Geological Survey's National Water-Quality Assessment Program, sampled Asiatic clams (Corbicula fluminea) and yellow bullhead (Ameiurus natalis) at 16 sites to determine the occurrence and distribution of 29 hydrophobic organic compounds. Thirteen of these organic compounds were detected in the survey. Sites with the greatest number of compounds detected include the Potomac River near Alexandria, Va., with 6 compounds detected in Asiatic clam tissue, and Accotink Creek near Annandale, Va., with 11 compounds in yellow bullhead tissue. Chlordane was detected at six sites, with maximum concentrations of 31.1 ?g/kg (micrograms per kilograms) in Asiatic clam tissue and 127 ?g/kg in yellow bullhead whole-fish tissue. DDT was detected at five sites, with maximum concentrations of 12.9 ?g/kg in Asiatic clam tissue and 7.6 ?g/kg in yellow bullhead whole-fish tissue. PCB's were detected at nine sites, with maximum concentrations of 162 ?g/kg in Asiatic clam tissue and 146 mg/ kg in yellow bullhead whole-fish tissue.

  19. Is the Ghost of Waste Management's Past Coming Back to Haunt Us In Our Seafood?

    NASA Astrophysics Data System (ADS)

    Rochman, C. M.; Tahir, A.; Serrato, S.; Williams, S.; Baxa, D.; Lam, R.; Teh, C.; Miller, J.; Werorilangi, S.; Teh, S.

    2016-02-01

    Plastic debris is recognized globally as a persistent contaminant, littered across multiple habitats worldwide. Most striking is its occurrence in wildlife. Plastic has been recovered from hundreds of species across multiple trophic levels and in animals we consider seafood. This has led policy-makers to ask about the extent that our seafood is contaminated with plastic debris and associated contaminants. To help address these policy-relevant and emerging scientific questions, we first measured the simple presence of anthropogenic debris in many different species of fish and one species of shellfish sold as seafood at local fish markets in Half Moon Bay, California, USA and Makassar, Sulawesi, Indonesia. We found anthropogenic debris in roughly 25% of all animals purchased, demonstrating that some seafood items are contaminated with plastic debris, including some that we consume whole (e.g., anchovies and oysters). Next, to understand if plastic debris can act as a vector for organic pollutants to move through the food chain and indirectly into the meat of fish at higher trophic levels, we designed a laboratory dietary exposure to measure the bioaccumulation of sorbed PCBs in Asian clams (Corbicula fluminea) and the biomagnifications in white sturgeon (Acipenser transmontanus). Asian clams were exposed for 30 days to separate treatments of microplastic (polyethylene terephthalate, polyethylene, polyvinyl chloride and polystyrene) with and without sorbed PCBs. Next, diets were formulated using purified ingredients and clams from the first exposure and fed to their predators (sturgeon) for 30 days. Chemical analyses, allowing us to understand how chemical contaminants from plastics move through food chains, will be presented. Combined, this work demonstrates the presence of plastic debris in seafood and will help us understand whether plastic acts as a vector for chemicals to transfer through aquatic foodwebs, including our own.

  20. Toxicokinetics/toxicodynamics links bioavailability for assessing arsenic uptake and toxicity in three aquaculture species.

    PubMed

    Chen, Wei-Yu; Liao, Chung-Min

    2012-11-01

    The purpose of this study was to link toxicokinetics/toxicodynamics (TK/TD) and bioavailability-based metal uptake kinetics to assess arsenic (As) uptake and bioaccumulation in three common farmed species of tilapia (Oreochromis mossambicus), milkfish (Chanos chanos), and freshwater clam (Corbicula fluminea). We developed a mechanistic framework by linking damage assessment model (DAM) and bioavailability-based Michaelis-Menten model for describing TK/TD and As uptake mechanisms. The proposed model was verified with published acute toxicity data. The estimated TK/TD parameters were used to simulate the relationship between bioavailable As uptake and susceptibility probability. The As toxicity was also evaluated based on a constructed elimination-recovery scheme. Absorption rate constants were estimated to be 0.025, 0.016, and 0.175 mL g(-1) h(-1) and As uptake rate constant estimates were 22.875, 63.125, and 788.318 ng g(-1) h(-1) for tilapia, milkfish, and freshwater clam, respectively. Here we showed that a potential trade-off between capacities of As elimination and damage recovery was found among three farmed species. Moreover, the susceptibility probability can also be estimated by the elimination-recovery relations. This study suggested that bioavailability-based uptake kinetics and TK/TD-based DAM could be integrated for assessing metal uptake and toxicity in aquatic organisms. This study is useful to quantitatively assess the complex environmental behavior of metal uptake and implicate to risk assessment of metals in aquaculture systems.

  1. Sediment toxicity and bioaccumulation of nano and micron-sized aluminum oxide.

    PubMed

    Stanley, Jacob K; Coleman, Jessica G; Weiss, Charles A; Steevens, Jeffery A

    2010-02-01

    Nano-aluminum oxide (Al(2)O(3)) is used commercially in coatings and abrasives. Nano-Al(2)O(3) can also be generated through the oxidation of nano-aluminum in military propellants and energetics. The purpose of the present study was to assess toxicity and bioaccumulation of nano-Al(2)O(3) to a variety of sediment organisms (Tubifex tubifex, Hyalella azteca, Lumbriculus variegatus, and Corbicula fluminea). The bioaccumulation and toxicity of nano-Al(2)O(3) was compared with that of micron-sized Al(2)O(3) to investigate potential size-related effects. Results of the present study show species-specific differences in relative bioaccumulation of nano and micron-sized Al(2)O(3). Significant toxic effects (survival and growth) were observed in H. azteca testing, but only at high concentrations unlikely to be found in the environment. Nano-Al(2)O(3) was found to be more toxic than micron-sized Al(2)O(3) to H. azteca survival in a 14-d study in which organisms were in direct contact with a thin layer of 625 or 2,500 mg of Al(2)O(3) dispersed on the surface of either sediment or sand. A significant growth effect was also observed for nano but not micron-sized Al(2)O(3) at the highest treatment level tested (100 g/kg Al(2)O(3)) in a 10-d H. azteca bioassay in which Al(2)O(3) was homogenized with sediment. However, differences in measured sediment Al concentrations (micron-sized = 55.1 [+/-0.6] g/kg Al; nano-sized = 66.2 [+/-0.6] g/kg Al) in the nano and micron-sized Al(2)O(3) preclude direct comparison of the toxicity of these two treatments based on particle size.

  2. Predation on exotic zebra mussels by native fishes: Effects on predator and prey

    USGS Publications Warehouse

    Magoulick, D.D.; Lewis, L.C.

    2002-01-01

    1. Exotic zebra mussels, Dreissena polymorpha, occur in southern U.S. waterways in high densities, but little is known about the interaction between native fish predators and zebra mussels. Previous studies have suggested that exotic zebra mussels are low profitability prey items and native vertebrate predators are unlikely to reduce zebra mussel densities. We tested these hypotheses by observing prey use of fishes, determining energy content of primary prey species of fishes, and conducting predator exclusion experiments in Lake Dardanelle, Arkansas. 2. Zebra mussels were the primary prey eaten by 52.9% of blue catfish, Ictalurus furcatus; 48.2% of freshwater drum, Aplodinotus grunniens; and 100% of adult redear sunfish, Lepomis microlophus. Blue catfish showed distinct seasonal prey shifts, feeding on zebra mussels in summer and shad, Dorosoma spp., during winter. Energy content (joules g-1) of blue catfish prey (threadfin shad, Dorosoma petenense; gizzard shad, D. cepedianum; zebra mussels; and asiatic clams, Corbicula fluminea) showed a significant species by season interaction, but shad were always significantly greater in energy content than bivalves examined as either ash-free dry mass or whole organism dry mass. Fish predators significantly reduced densities of large zebra mussels (>5 mm length) colonising clay tiles in the summers of 1997 and 1998, but predation effects on small zebra mussels (???5 mm length) were less clear. 3. Freshwater drum and redear sunfish process bivalve prey by crushing shells and obtain low amounts of higher-energy food (only the flesh), whereas blue catfish lack a shell-crushing apparatus and ingest large amounts of low-energy food per unit time (bivalves with their shells). Blue catfish appeared to select the abundant zebra mussel over the more energetically rich shad during summer, then shifted to shad during winter when shad experienced temperature-dependent stress and mortality. Native fish predators can suppress adult zebra

  3. Concentrations of metals in aquatic invertebrates from the Ozark National Scenic Riverways, Missouri

    USGS Publications Warehouse

    Schmitt, Christopher J.; Brumbaugh, William G.; Besser, John M.; May, Thomas W.

    2007-01-01

    This report summarizes the findings of a study conducted as a pilot for part of a park-wide monitoring program being developed for the Ozark National Scenic Riverways (ONSR) of southeastern Missouri. The objective was to evaluate using crayfish (Orconectes spp.) and Asian clam (Corbicula fluminea) for monitoring concentrations of metals associated with lead-zinc mining. Lead-zinc mining presently (2007) occurs near the ONSR and additional mining has been proposed. Three composite samples of each type (crayfish and Asian clam), each comprising ten animals of approximately the same size, were collected during late summer and early fall of 2005 from five sites on the Current River and Jacks Fork within the ONSR and from one site on the Eleven Point River and the Big River, which are outside the ONSR. The Big River has been contaminated by mine tailings from historical leadzinc mining. Samples were analyzed by inductively coupled plasma mass spectrometry for lead, zinc, cadmium, cobalt, and nickel concentrations. All five metals were detected in all samples; concentrations were greatest in samples of both types from the Big River, and lowest in samples from sites within the ONSR. Concentrations of zinc and cadmium typically were greater in Asian clams than in crayfish, but differences were less evident for the other metals. In addition, differences among sites were small for cobalt in Asian clams and for zinc in crayfish, indicating that these metals are internally regulated to some extent. Consequently, both sample types are recommended for monitoring. Concentrations of metals in crayfish and Asian clams were consistent with those reported by other studies and programs that sampled streams in southeast Missouri.

  4. Trace elements in bed sediments and aquatic invertebrates from three streams in Nevada

    SciTech Connect

    Lawrence, S.

    1995-12-31

    In September 1992, the US Geological Survey, as part of the National Water Quality Assessment Program, collected crayfish (Pacifastacus Ieniusculus and Procambarus clarkii), asiatic clam (Corbicula fluminea), caddis-fly larvae (Hydropsyche spp.) and bed-sediment samples from the Truckee and Carson Rivers, and Las Vegas Wash in Nevada and analyzed them for selected trace elements. This report describes and compares the concentrations of arsenic, copper, manganese, mercury, silver, and zinc in those samples. In the Truckee and Carson Rivers, concentrations of the six trace elements in aquatic invertebrate samples are similar to concentrations measured in bed sediments. In the Truckee River, concentrations of these elements in crayfish and bed-sediment samples were highest in the Reno-Sparks urban area. In the Carson River, arsenic and copper are highest in bed-sediment samples upstream of Carson City due to geothermal springs and acid-mine drainage from an abandoned sulfur mine; concentrations of manganese, mercury, silver, and zinc were highest in bed-sediment samples collected downstream of the Carson City urban area due to historic gold and silver mining, and urban runoff. The highest mercury concentration in crayfish tissue, 48 {micro}g/g dry weight, was measured in a sample from the lower Carson River. In Las Vegas Wash, bed-sediment concentrations were lower than those in the Truckee and Carson Rivers; but, trace-element concentrations in crayfish tissue tended to be higher than those in bed sediment. Samples collected during this study show that trace elements are enriched in the bed sediments of all three rivers and are bioavailable. Trace-element concentrations among samples of crayfish, asiatic clam, and caddis-fly larvae showed little similarity.

  5. Mercury in bottom sediment and aquatic invertebrates, Carson and Truckee River Basins, Nevada and California

    SciTech Connect

    Lawrence, S.J.; Bevans, H.E.

    1994-12-31

    Bottom sediment and aquatic invertebrates were sampled for trace-element analyses at 11 sites in the Carson and Truckee River Basins during September 1 992 as part of the US Geological Survey`s National Water-Quality Assessment Program. Composite bottom-sediment samples from inundated depositional areas were wet-sieved through a 63-micrometer nylon mesh and composite aquatic invertebrate samples were allowed to depurate prior to analyses. In the Carson River Basin, mercury concentrations increased downstream from 0.24 microgram per gram, dry weight ({mu}g/g), in both bottom sediment and western crayfish (Pacifastacus leniusculus) samples from the East Fork Carson River near Markleeville, Calif., to 5.9 {mu}g/g in bottom sediment in the Carson River near Fallon, Nev., and to 48 {mu}g/g in western crayfish in the river near Fort Churchill, Nev. Asiatic clams (Corbicula fluminea) from the Carson River at Fort Churchill and near Fallon had 6.1 and 1.4 {mu}g/g of mercury, respectively. In the Truckee River Basin, mercury concentrations increased downstream from 0.02 {mu}g/g in bottom sediment and 0.17--0.21 {mu}g/g in western crayfish at sites upstream of Reno, Nev., to 0.58 {mu}g/g in bottom sediment and 0.49 {mu}g/g in western crayfish at Clark, Nev. Downstream patterns of mercury concentration in bottom sediment and western crayfish are similar. Possible sources of mercury include historical gold and silver ore-milling activities, acid mine drainage, mineral deposits, and urban activities.

  6. Solar influences on global change

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Monitoring of the Sun and the Earth has yielded new knowledge essential to this debate. There is now no doubt that the total radiative energy from the Sun that heats the Earth's surface changes over decadal time scales as a consequence of solar activity. Observations indicate as well that changes in ultraviolet radiation and energetic particles from the Sun, also connected with the solar activity, modulate the layer of ozone that protects the biosphere from the solar ultraviolet radiation. This report reassesses solar influences on global change in the light of this new knowledge of solar and atmospheric variability. Moreover, the report considers climate change to be encompassed within the broader concept of global change; thus the biosphere is recognized to be part of a larger, coupled Earth system. Implementing a program to continuously monitor solar irradiance over the next several decades will provide the opportunity to estimate solar influences on global change, assuming continued maintenance of observations of climate and other potential forcing mechanisms. In the lower atmosphere, an increase in solar radiation is expected to cause global warming. In the stratosphere, however, the two effects produce temperature changes of opposite sign. A monitoring program that would augment long term observations of tropospheric parameters with similar observations of stratospheric parameters could separate these diverse climate perturbations and perhaps isolate a greenhouse footprint of climate change. Monitoring global change in the troposphere is a key element of all facets of the United States Global Change Research Program (USGCRP), not just of the study of solar influences on global change. The need for monitoring the stratosphere is also important for global change research in its own right because of the stratospheric ozone layer.

  7. Saltwater upconing zone of influence

    NASA Astrophysics Data System (ADS)

    Jakovovic, Danica; Werner, Adrian D.; de Louw, Perry G. B.; Post, Vincent E. A.; Morgan, Leanne K.

    2016-08-01

    In this study, we define and characterize the saltwater upconing zone of influence (SUZI). The SUZI is the region around a pumping well within which significant rise in the saltwater-freshwater interface occurs. While the zone of influence of a pumping well can be clearly defined in terms of hydraulics (e.g., drawdown), the SUZI has not been recognised and characterised, despite its importance for groundwater decision-making in coastal regions. We explore the SUZI under various conditions and compare common methods of investigation using both axisymmetric (1D and 2D vertical cross-section) and 3D simulations of saltwater upconing at the field scale, based on a combination of numerical and analytical approaches. The SUZI was found to be dependent on the relative magnitudes of pumping, regional flow, distance of the well from the coast, and position of the well above the interface, as expected. The three-dimensional coastal setting simulations revealed an asymmetric shape of the lateral extent of the SUZI, which is largest in the direction parallel to the coast. This occurs because the ocean and the inland extent of the seawater wedge limit the propagation of the SUZI perpendicular to the coast. Predictions of the SUZI using the Ghyben-Herzberg approximation, including cases where sloping interfaces occur (i.e., in contrast to the artificiality of horizontal interfaces used in axisymmetric approaches), provide reasonable first approximations of the SUZI. Numerical modelling of dispersive upconing in the 3D inclined interface case is influenced by practical limits to the model domain size and grid resolution. For example, the no-flow boundary condition at 1500 m from the pumping well elongates the SUZI in the direction parallel to the coast. This study extends previous concepts of well interference, which have previously been based on hydraulics only, by introducing the SUZI and characterising its extent, with consideration given to differences in commonly adopted

  8. Visual influences on primate encephalization.

    PubMed

    Kirk, E Christopher

    2006-07-01

    Primates differ from most other mammals in having relatively large brains. As a result, numerous comparative studies have attempted to identify the selective variables influencing primate encephalization. However, none have examined the effect of the total amount of visual input on relative brain size. According to Jerison's principle of proper mass, functional areas of the brain devoted primarily to processing visual information should exhibit increases in size when the amount of visual input to those areas increases. As a result, the total amount of visual input to the brain could exert a large influence on encephalization because visual areas comprise a large proportion of total brain mass in primates. The goal of this analysis is to test the expectation of a direct relationship between visual input and encephalization using optic foramen size and optic nerve size as proxies for total visual input. Data were collected for a large comparative sample of primates and carnivorans, and three primary analyses were undertaken. First, the relationship between relative proxies for visual input and relative endocranial volume were examined using partial correlations and phylogenetic comparative methods. Second, to examine the generality of the results derived for extant primates, a parallel series of partial correlation and comparative analyses were undertaken using data for carnivorans. Third, data for various Eocene and Oligocene primates were compared with those for living primates in order to determine whether the fossil taxa demonstrate a similar relationship between relative brain size and visual input. All three analyses confirm the expectations of proper mass and favor the conclusion that the amount of visual input has been a major influence on the evolution of relative brain size in both primates and carnivorans. Furthermore, this study suggests that differences in visual input may partly explain (1) the high encephalization of primates relative to the primitive

  9. Captain's and first officers' spheres of influence.

    PubMed

    Law, J R; Wilhelm, J A

    1994-01-01

    Although the "crew is increasingly the unit of focus for technical and CRM Training, a recent study documented that individual crew members exert influence over the crew in unique ways. The actions of captains and first officers influenced the overall performance of the "crew" both positively and negatively. Captains most often used briefings and leadership behaviors to influence crews. First Officers, on the other hand, influenced crew performance by their use of Inquiry / Assertion / Advocacy, Preparation / Planning / Vigilance activities, and Technical Proficiency.

  10. Gravitational influence on eutectic solidification

    NASA Technical Reports Server (NTRS)

    Sokolowski, Robert S.; Glicksman, Martin E.

    1992-01-01

    The effect of gravity on eutectic solidification was investigated experimentally for Pb-Sn binary eutectic alloys. It is found that the separation of the primary crystals of the binary system from the coupled eutectic occurs over a wide range of cooling rates and gravitational fields (100-100,000 g). The separation is strongly influenced by the nucleation behavior of the particular alloy system. A mechanism for the strong phase separation is postulated on the basis of cloud convection models in atmospheric convection.

  11. "Influence Method". Detailed mathematical description

    NASA Astrophysics Data System (ADS)

    Rios, I. J.; Mayer, R. E.

    2015-07-01

    A new method for the absolute determination of nuclear particle flux in the absence of known detector efficiency, the "Influence Method", was recently published (I.J. Rios and R.E. Mayer, Nuclear Instruments & Methods in Physics Research A 775 (2015) 99-104). The method defines an estimator for the population and another estimator for the efficiency. In this article we present a detailed mathematical description which yields the conditions for its application, the probability distributions of the estimators and their characteristic parameters. An analysis of the different cases leads to expressions of the estimators and their uncertainties.

  12. Peptides that influence membrane topology

    NASA Astrophysics Data System (ADS)

    Wong, Gerard C. L.

    2014-03-01

    We examine the mechanism of a range of polypeptides that influence membrane topology, including antimicrobial peptides, cell penetrating peptides, viral fusion peptides, and apoptosis proteins, and show how a combination of geometry, coordination chemistry, and soft matter physics can be used to approach a unified understanding. We will also show how such peptides can impact biomedical problems such as auto-immune diseases (psoriasis, lupus), infectious diseases (viral and bacterial infections), and mitochondrial pathologies (under-regulated apoptosis leads to neurodegenerative diseases whereas over-regulated apoptosis leads to cancer.)

  13. Paradoxical communication as interpersonal influence.

    PubMed

    Bogdan, J L

    1982-12-01

    This paper is concerned with the strategic uses of paradoxical communication in therapy. Eight more or less distinct uses of paradoxical communication are described, and the proposition is put forward that the paradoxical interventions associated with the Milan group differ from those described by Haley and the Palo Alto group only in that they appear to be designed to influence simultaneously the behavior of several family members. The currently popular idea that such interventions should, or even can, be based on a systemic hypothesis, if "hypothesis" is understood in its usual sense as a statement amenable to empirical testing, is explicitly questioned.

  14. Culture and Influence in Multisite Evaluation

    ERIC Educational Resources Information Center

    Kirkhart, Karen E.

    2011-01-01

    Understanding the influence of multisite evaluation requires careful consideration of cultural context. The author illustrates dimensions of influence and culture with excerpts from four National Science Foundation evaluation case studies and summarizes what influence teaches everyone about culture and what culture teaches everyone about…

  15. Interpersonal Influence Styles of Adult Cohorts.

    ERIC Educational Resources Information Center

    Hoffman, Stephanie B.

    Generational differences in the balance of power contribute to varying patterns of influence strategy use within cohorts of young, middle-aged, and older adults. The self-report Likelihood of Influence Tactic Use Scale was administered to 10 males and 10 females in each of three cohort groups to investigate the influence tactics used at different…

  16. Lexical Influences on Auditory Streaming

    PubMed Central

    Billig, Alexander J.; Davis, Matthew H.; Deeks, John M.; Monstrey, Jolijn; Carlyon, Robert P.

    2013-01-01

    Summary Biologically salient sounds, including speech, are rarely heard in isolation. Our brains must therefore organize the input arising from multiple sources into separate “streams” and, in the case of speech, map the acoustic components of the target signal onto meaning. These auditory and linguistic processes have traditionally been considered to occur sequentially and are typically studied independently [1, 2]. However, evidence that streaming is modified or reset by attention [3], and that lexical knowledge can affect reports of speech sound identity [4, 5], suggests that higher-level factors may influence perceptual organization. In two experiments, listeners heard sequences of repeated words or acoustically matched nonwords. After several presentations, they reported that the initial /s/ sound in each syllable formed a separate stream; the percept then fluctuated between the streamed and fused states in a bistable manner. In addition to measuring these verbal transformations, we assessed streaming objectively by requiring listeners to detect occasional targets—syllables containing a gap after the initial /s/. Performance was better when streaming caused the syllables preceding the target to transform from words into nonwords, rather than from nonwords into words. Our results show that auditory stream formation is influenced not only by the acoustic properties of speech sounds, but also by higher-level processes involved in recognizing familiar words. PMID:23891107

  17. Familial influences on adolescent smoking.

    PubMed

    Avenevoli, Shelli; Merikangas, Kathleen Ries

    2003-05-01

    The family unit is the primary source of transmission of basic social, cultural, genetic, and biological factors that may underlie individual differences in smoking. Existing information on the role of familial factors in tobacco use is characterized by two separate, but somewhat overlapping, lines of research: genetic epidemiological studies and risk-factor research. The present paper summarizes and evaluates studies assessing the association between adolescent smoking and parent and sibling smoking behaviors. A review of 87 studies reveals that methods are limited by a lack of standardized instruments, failure to measure important confounding and mediating factors, reliance on cross-sectional designs and the use of inconsistent definitions of tobacco-related behavior and assessment procedures. Moreover, there are no systematic family studies of the acquisition and continuation of smoking that have employed contemporary methodological standards for examining familial aggregation of tobacco behaviors among adolescents. Findings across studies show weak and inconsistent associations between parent and adolescent smoking; inconsistent findings may be attributed to methodological issues or associated factors that may complicate the relation between parent and adolescent smoking. Sibling and peer smoking show greater associations with adolescent smoking. Suggestions for future research include contemporary family studies that delineate meaningful phenotypes of tobacco use and prospective work on the later stages of tobacco use and the timing of the influence and valence of parent and family factors. Integration of the risk factor approach within the family study design may enrich both approaches to elucidate familial influences on smoking.

  18. Influence of convection on microstructure

    NASA Technical Reports Server (NTRS)

    Wilcox, William R.; Eisa, Gaber Faheem; Chandrasekhar, S.; Larrousse, Mark; Banan, Mohsen

    1988-01-01

    The influence was studied of convection during directional solidification on the resulting microstructure of eutectics, specifically lead/tin and manganese/bismuth. A theory was developed for the influence of convection on the microstructure of lamellar and fibrous eutectics, through the effect of convection on the concentration field in the melt in front of the growing eutectic. While the theory agrees with the experimental spin-up spin-down results, it predicts that the weak convection expected due to buoyancy will not produce a measurable change in eutectic microstructure. Thus, this theory does not explain the two fold decrease in MnBi fiber size and spacing observed when MnBi-Bi is solidified in space or on Earth with a magnetic field applied. Attention was turned to the morphology of the MnBi-Bi interface and to the generation of freezing rate fluctuations by convection. Decanting the melt during solidification of MnBi-Bi eutectic showed that the MnBi phase projects into the melt ahead of the Bi matrix. Temperature measurements in a Bi melt in the vertical Bridgman-Stockbarger configuration showed temperature variations of up to 25 C. Conclusions are drawn and discussed.

  19. Corona Discharge Influence on Moulds

    NASA Astrophysics Data System (ADS)

    Scholtz, Vladimir

    2004-09-01

    It is known that the electric discharge has bacteriocid effect. We are interesting on influence of corona discharge on moulds and searching for it's fungicide effect. In this work we study the mould penicillium digitatum by using an easy apparatus, where may be situated two measured samples. One in the burning corona discharge and one in the area with ozone generated by this corona only. We expose the spores of penicillium digitatum on a metal plate and on a cultivating medium on cca 0.01mA, 5kV corona discharge and on generated ozone only for time cca two days. It is the time needed for sprouting of spores and growing of they to a visible size. The pilot results show, that the ozone generated by the corona discharge has none or very low influence on the sprouting and growing of the spores. Direct corona discharge inhibit the sprouting only, but does not kill the spores. In next experiments we will try to find some minimum inhibit and killing concentration of ozone and try to expose the sprout inhibition.

  20. [Factors influencing vitality among nurses].

    PubMed

    Lee, Ji-Soon; Oh, Won-Oak

    2007-08-01

    This study was conducted to understand the degree of vitality, meaning in life and self-efficacy and to elucidate the factors influencing this vitality in the nurses of Korea. A cross-sectional survey of nurses from 4 hospitals was conducted by convenience sampling. Data collection was conducted through the use of questionnaires which were constructed to include a Vitality Self Test, Purpose in Life Test and Self-efficacy Scale. The degree of vitality in nurses was in the middle range. The nurses of this study had few goals towards meaning in life, and an existential vacuum state. A positive relationship was found between vitality and the research variables. The significant predictors influencing vitality in nurses were meaning in life, self-efficacy, and clinical career, and these variables accounted for 28.7% of the variance in vitality. This results support that vitality is an important link with meaning in life and self-efficacy. There should be a comprehensive study in the future for in-depth understanding of the vitality of nurses.

  1. Pesticides' influence on wine fermentation.

    PubMed

    Caboni, Pierluigi; Cabras, Paolo

    2010-01-01

    Wine quality strongly depends on the grape quality. To obtain high-quality wines, it is necessary to process healthy grapes at the correct ripeness stage and for this reason the farmer has to be especially careful in the prevention of parasite attacks on the grapevine. The most common fungal diseases affecting grape quality are downy and powdery mildew (Plasmopara viticola and Uncinula necator), and gray mold (Botrytis cinerea). On the other hand, the most dangerous insects are the grape moth (Lobesia botrana), vine mealybug (Planococcus ficus), and the citrus mealybug (Planococcus citri). Farmers fight grape diseases and insects applying pesticides that can be found at harvest time on grapes. The persistence of pesticides depends on the chemical characteristic of the active ingredients as well as on photodegradation, thermodegradation, codistillation, and enzymatic degradation. The pesticide residues on grapes can be transferred to the must and this can influence the selection and development of yeast strains. Moreover, yeasts can also influence the levels of the pesticides in the wine by reducing or adsorbing them on lees. During the fermentative process, yeasts can cause the disappearance of pesticide residues by degradation or absorption at the end of the fermentation when yeasts are deposited as lees. In this chapter, we reviewed the effect of commonly used herbicides, insecticides, and fungicides on yeasts. We also studied the effect of alcoholic and malolactic fermentation on pesticide residues.

  2. Atmospheric composition - Influence of biology

    NASA Technical Reports Server (NTRS)

    Mcelroy, M. B.

    1983-01-01

    The variability of atmospheric constituents influenced by biological organisms over various time scales is examined, together with the human contribution to atmospheric sulfur. The biogeochemistry of nitrogen is discussed, with an emphasis on N2O, NO, and microbially mediated reactions in soil and water. Carbon species are bound up mainly in sediments and the deep ocean, but human activities involving combustion may cause a doubling of the atmospheric levels of CO2 in the near future, which could produce a general low-level atmospheric warming. Longer term measurements are required to assess the effects of CH4 augmentation in the atmosphere through fuel combustion. Coal burning effectively doubles the amount of SO2 produced by natural sources, and reduces the pH of rainwater, thus posing hazards to fish, plankton, and mollusc life.

  3. Grasp observation influences speech production.

    PubMed

    Gentilucci, Maurizio

    2003-01-01

    Subjects pronounced either the syllable 'BA' or 'GA' while observing motor acts of hand grasp directed to objects of two sizes (experiment 1). Kinematics of lip aperture and amplitude spectrum of voice were influenced by the observation of the different grasp kinematics depending on the size of the target objects. Specifically, both lip aperture and voice peak amplitude were greater when the observed hand grasp was directed to the large object. Two control experiments ruled out that the different arm velocity when reaching objects varying in size (experiment 2), and overt visual analysis of the target-object (experiment 3), affected lip movement and voice emission. Results provide behavioural evidence in favour of the hypothesis that the system involved in observation (and preparation) of grasp movements partially shares the cortical areas involved in speech production.

  4. Atmospheric composition - Influence of biology

    NASA Technical Reports Server (NTRS)

    Mcelroy, M. B.

    1983-01-01

    The variability of atmospheric constituents influenced by biological organisms over various time scales is examined, together with the human contribution to atmospheric sulfur. The biogeochemistry of nitrogen is discussed, with an emphasis on N2O, NO, and microbially mediated reactions in soil and water. Carbon species are bound up mainly in sediments and the deep ocean, but human activities involving combustion may cause a doubling of the atmospheric levels of CO2 in the near future, which could produce a general low-level atmospheric warming. Longer term measurements are required to assess the effects of CH4 augmentation in the atmosphere through fuel combustion. Coal burning effectively doubles the amount of SO2 produced by natural sources, and reduces the pH of rainwater, thus posing hazards to fish, plankton, and mollusc life.

  5. [Proteins influencing the blood coagulation].

    PubMed

    Alberio, Lorenzo

    2011-11-01

    This review describes some natural proteins, which can be employed, either as factor concentrates derived from human plasma or as recombinant drug, to modulate the coagulation system. I will address some biochemical characteristics and the physiological role of von Willebrand factor, the coagulation factors of the extrinsic and intrinsic pathways, and the physiological anticoagulant protein C. In addition, I will detail the pharmacological compounds, which are available for influencing or substituting the coagulation proteins: desmopressin (DDAVP), single coagulation factor concentrates, prothrombin complex concentrates, and protein C concentrate. In particular, I will address some treatment topics of general medical interest, such as the treatment of massive bleeding, the correction of the coagulopathy induced by vitamin K-antagonists in patients with cerebral haemorrhage, and of the coagulopathy of meningococcemia. Finally, I will describe some properties and practical clinical applications of the recombinant anticoagulans lepirudin and bivalirudin, which are derived from hirudin, the natural anticoagulant of the medical leech.

  6. [Do antioxidant vitamins influence carcinogenesis?].

    PubMed

    Guz, Jolanta; Dziaman, Tomasz; Szpila, Anna

    2007-01-01

    Free radicals can affect the genetic material of cells, causing its gradual impairment and mutation. An accumulation of mutations in certain genes might lead to neoplasmic transformations of the cells and to cancer development. The deteriorative effects of free radicals are counteracted by the antioxidant vitamins A, C, and E that quench free radical reactions. Fruits and vegetables are excellent sources of antioxidant vitamins. The following article attempts a short review of the current knowledge about the influence of vitamins A, C, and E on oxidative damage to DNA, the activity of some transcription factors, and the expressions of certain genes. The aim of this review is to answer the question whether a diet rich in vitamins can protect against cancer.

  7. Human diffusion and city influence

    PubMed Central

    Lenormand, Maxime; Gonçalves, Bruno; Tugores, Antònia; Ramasco, José J.

    2015-01-01

    Cities are characterized by concentrating population, economic activity and services. However, not all cities are equal and a natural hierarchy at local, regional or global scales spontaneously emerges. In this work, we introduce a method to quantify city influence using geolocated tweets to characterize human mobility. Rome and Paris appear consistently as the cities attracting most diverse visitors. The ratio between locals and non-local visitors turns out to be fundamental for a city to truly be global. Focusing only on urban residents' mobility flows, a city-to-city network can be constructed. This network allows us to analyse centrality measures at different scales. New York and London play a central role on the global scale, while urban rankings suffer substantial changes if the focus is set at a regional level. PMID:26179991

  8. How do stereotypes influence choice?

    PubMed

    Chaxel, Anne-Sophie

    2015-05-01

    In the study reported here, I tracked one process through which stereotypes affect choice. The Implicit Association Test (IAT) and a measurement of predecisional information distortion were used to assess the influence of the association between male gender and career on the evaluation of information related to the job performance of stereotypical targets (male) and nonstereotypical targets (female). When the IAT revealed a strong association between male gender and career and the installed leader in the choice process was a stereotypical target, decision makers supported the leader with more proleader distortion; when the IAT revealed a strong association between male gender and career and the installed leader in the choice process was a nonstereotypical target, decision makers supported the trailer with less antitrailer distortion. A stronger association between male gender and career therefore resulted in an upward shift of the evaluation related to the stereotypical target (both as a trailer and a leader), which subsequently biased choice.

  9. Serpentinization processes: Influence of silica

    NASA Astrophysics Data System (ADS)

    Huang, R.; Sun, W.; Ding, X.; Song, M.; Zhan, W.

    2016-12-01

    Serpentinization systems are highly enriched in molecular hydrogen (H2) and hydrocarbons (e.g. methane, ethane and propane). The production of hydrocarbons results from reactions between H2 and oxidized carbon (carbon dioxide and carbon monoxide), which possibly contribute to climate changes during early history of the Earth. However, the influence of silica on the production of H2 and hydrocarbons was poorly constrained. We performed experiments at 311-500 °C and 3.0 kbar using mechanical mixtures of silica and olivine in ratios ranging from 0 to 40%. Molecular hydrogen (H2), methane, ethane and propane were formed, which were analyzed by gas chromatography. It was found that silica largely decreased H2 production. Without any silica, olivine serpentinization produced 94.5 mmol/kg H2 after 20 days of reaction time. By contrast, with the presence of 20% silica, H2 concentrations decreased largely, 8.5 mmol/kg. However, the influence of silica on the production of hydrocarbons is negligible. Moreover, with the addition of 20%-40% silica, the major hydrous minerals are talc, which was quantified according to an established standard curve calibrated by infrared spectroscopy analyses. It shows that silica greatly enhances olivine hydration, especially at 500 °C. Without any addition of silica, reaction extents were <5% at 17 days during olivine serpentinization at 500 °C and 3.0 kbar. By contrast, with the presence of 50% silica, olivine was completely transformed to talc within 9 days. This study indicates that silica impedes the oxidation of ferrous iron into ferric iron, and that rates of olivine hydration in natural geological settings are much faster with silica supply.

  10. Influence diagnostics in meta-regression model.

    PubMed

    Shi, Lei; Zuo, ShanShan; Yu, Dalei; Zhou, Xiaohua

    2017-07-18

    This paper studies the influence diagnostics in meta-regression model including case deletion diagnostic and local influence analysis. We derive the subset deletion formulae for the estimation of regression coefficient and heterogeneity variance and obtain the corresponding influence measures. The DerSimonian and Laird estimation and maximum likelihood estimation methods in meta-regression are considered, respectively, to derive the results. Internal and external residual and leverage measure are defined. The local influence analysis based on case-weights perturbation scheme, responses perturbation scheme, covariate perturbation scheme, and within-variance perturbation scheme are explored. We introduce a method by simultaneous perturbing responses, covariate, and within-variance to obtain the local influence measure, which has an advantage of capable to compare the influence magnitude of influential studies from different perturbations. An example is used to illustrate the proposed methodology. Copyright © 2017 John Wiley & Sons, Ltd.

  11. Information-based physics, influence, and forces

    SciTech Connect

    Walsh, James Lyons; Knuth, Kevin H.

    2015-01-13

    In recent works, Knuth and Bahreyni have demonstrated that the concepts of space and time are emergent in a coarse-grained model of direct particle-particle influence. In addition, Knuth demonstrated that observer-made inferences regarding the free particle, which is defined as a particle that influences others, but is not itself influenced, result in a situation identical to the Feynman checkerboard model of the Dirac equation. This suggests that the same theoretical framework that gives rise to an emergent spacetime is consistent with quantum mechanics. In this paper, we begin to explore the effect of influence on the emergent properties of a particle. This initial study suggests that when a particle is influenced, it is interpreted as accelerating in a manner consistent with special relativity implying that, at least in this situation, influence can be conceived of as a force.

  12. Information-based physics, influence, and forces

    NASA Astrophysics Data System (ADS)

    Walsh, James Lyons; Knuth, Kevin H.

    2015-01-01

    In recent works, Knuth and Bahreyni have demonstrated that the concepts of space and time are emergent in a coarse-grained model of direct particle-particle influence. In addition, Knuth demonstrated that observer-made inferences regarding the free particle, which is defined as a particle that influences others, but is not itself influenced, result in a situation identical to the Feynman checkerboard model of the Dirac equation. This suggests that the same theoretical framework that gives rise to an emergent spacetime is consistent with quantum mechanics. In this paper, we begin to explore the effect of influence on the emergent properties of a particle. This initial study suggests that when a particle is influenced, it is interpreted as accelerating in a manner consistent with special relativity implying that, at least in this situation, influence can be conceived of as a force.

  13. Influence of convection on microstructure

    NASA Technical Reports Server (NTRS)

    Wilcox, William R.; Regel, Liya L.

    1992-01-01

    The primary motivation for this research has been to determine the cause for space processing altering the microstructure of some eutectics, especially the MnBi-Bi eutectic. Prior experimental research at Grumman and here showed that the microstructure of MnBi-Bi eutectic is twice as fine when solidified in space or in a magnetic field, is uninfluenced by interfacial temperature gradient, adjusts very quickly to changes in freezing rate, and becomes coarser when spin-up/spin-down (accelerated crucible rotation technique) is used during solidification. Theoretical work at Clarkson predicted that buoyancy driven convection on earth could not account for the two fold change in fiber spacing caused by solidification in space. However, a lamellar structure with a planar interface was assumed, and the Soret effect was not included in the analysis. Experimental work at Clarkson showed that the interface is not planar, and that MnBi fibers project out in front of the Bi matrix on the order of one fiber diameter. Originally four primary hypotheses were to be tested under this current grant: (1) a fibrous microstructure is much more sensitive to convection than a lamellar microstructure, which was assumed in our prior theoretical treatment; (2) an interface with one phase projecting out into the melt is much more sensitive to convection than a planar interface, which was assumed in our prior theoretical treatment; (3) the Soret effect is much more important in the absence of convection and has a sufficiently large influence on microstructure that its action can explain the flight results; and (4) the microstructure is much more sensitive to convection when the composition of the bulk melt is off eutectic. As reported previously, we have learned that while a fibrous microstructure and a non-planar interface are more sensitive to convection than a lamellar microstructure with a planar interface, the influence of convection remains too small to explain the flight and magnetic

  14. Sociocultural Influences on Psychosocial Adjustment in Antarctica

    DTIC Science & Technology

    1985-12-01

    stage, the group is open, consisting of individuals who are removed from the direct influence of their accustomed sociocultural framework and are forced... groups , the harsh environment, and the prolonged isola- tion from outside contact. The degree of stress, however, is influenced by different...interaction of these influences . In parti- cular, as the heterogeneity of social group increases so does the potential for interper- sonal as well as

  15. Influence Diagrams: Automated Analysis with Dynamic Programming

    DTIC Science & Technology

    1988-12-01

    demonstrating both the efficiency of the dynamic programming features and the limitations of influence diagrams in modeling problems with significant...Introduction 1.1 General Background Influence diagrams are a -eccntly developed graphical modeling tool for repre- senting both the conceptual elements and the...the model [9:10]. The types of node included in basic influence diagrams are (see Figure 1): Chance Node The chance node represents a random variable

  16. Spouse Influence in Army Organizational Change

    DTIC Science & Technology

    2008-01-01

    important family life is to employees and soldiers, there is little research into how spouses influence the organization . Similarly, there is far less...communicating the change message to potential influencers who are outside the organization , such as family members. There is a growing field of research on...1947 field theory in which he asserts that 4 organizations are constantly influenced by forces that both require and resist change.9 When these

  17. Factors Influencing Odor Sensitivity in the Dog

    DTIC Science & Technology

    1975-10-01

    U.S. DEPARTMENT OF COMMERCE Natsual Techuical Imfwmatmi Suuwie AD-A024 267 FACTORS INFLUENCING ODOR SENSITIVITY IN THE DOG PENNSYLVANIA UNIVERSITY...PREPARED FOR AIR FORCE OFFICE OF SCIENTIFIC RESEARCH OCTOBER 1975 138097 FACTORS INFLUENCING ODOR SENSITIVITY IN THE DOG Final report - October, 1975...Subtitle) S. TYPE OF REPORT 6 PERIOD COVERED FACTORS INFLUENCING ODOR SENSITIVITY IN FIP.1 Scientific Report TlE DOG "Ś. PERFORMING ORG. REPORT NUMBER 7

  18. Social influence on risk perception during adolescence.

    PubMed

    Knoll, Lisa J; Magis-Weinberg, Lucía; Speekenbrink, Maarten; Blakemore, Sarah-Jayne

    2015-05-01

    Adolescence is a period of life in which peer relationships become increasingly important. Adolescents have a greater likelihood of taking risks when they are with peers rather than alone. In this study, we investigated the development of social influence on risk perception from late childhood through adulthood. Five hundred and sixty-three participants rated the riskiness of everyday situations and were then informed about the ratings of a social-influence group (teenagers or adults) before rating each situation again. All age groups showed a significant social-influence effect, changing their risk ratings in the direction of the provided ratings; this social-influence effect decreased with age. Most age groups adjusted their ratings more to conform to the ratings of the adult social-influence group than to the ratings of the teenager social-influence group. Only young adolescents were more strongly influenced by the teenager social-influence group than they were by the adult social-influence group, which suggests that to early adolescents, the opinions of other teenagers about risk matter more than the opinions of adults. © The Author(s) 2015.

  19. Social Influence on Risk Perception During Adolescence

    PubMed Central

    Magis-Weinberg, Lucía; Speekenbrink, Maarten; Blakemore, Sarah-Jayne

    2015-01-01

    Adolescence is a period of life in which peer relationships become increasingly important. Adolescents have a greater likelihood of taking risks when they are with peers rather than alone. In this study, we investigated the development of social influence on risk perception from late childhood through adulthood. Five hundred and sixty-three participants rated the riskiness of everyday situations and were then informed about the ratings of a social-influence group (teenagers or adults) before rating each situation again. All age groups showed a significant social-influence effect, changing their risk ratings in the direction of the provided ratings; this social-influence effect decreased with age. Most age groups adjusted their ratings more to conform to the ratings of the adult social-influence group than to the ratings of the teenager social-influence group. Only young adolescents were more strongly influenced by the teenager social-influence group than they were by the adult social-influence group, which suggests that to early adolescents, the opinions of other teenagers about risk matter more than the opinions of adults. PMID:25810453

  20. Influence of convection on microstructure

    NASA Technical Reports Server (NTRS)

    Wilcox, William R.; Caram, Rubens; Mohanty, A. P.; Seth, Jayshree

    1990-01-01

    In eutectic growth, as the solid phases grow they reject atoms to the liquid. This results in a variation of melt composition along the solid/liquid interface. In the past, mass transfer in eutectic solidification, in the absence of convection, was considered to be governed only by the diffusion induced by compositional gradients. However, mass transfer can also be generated by a temperature gradient. This is called thermotransport, thermomigration, thermal diffusion or the Soret effect. A theoretical model of the influence of the Soret effect on the growth of eutectic alloys is presented. A differential equation describing the compositional field near the interface during unidirectional solidification of a binary eutectic alloy was formulated by including the contributions of both compositional and thermal gradients in the liquid. A steady-state solution of the differential equation was obtained by applying appropriate boundary conditions and accounting for heat flow in the melt. Following that, the average interfacial composition was converted to a variation of undercooling at the interface, and consequently to microstructural parameters. The results obtained show that thermotransport can, under certain circumstances, be a parameter of paramount importance.

  1. Prenatal meditation influences infant behaviors.

    PubMed

    Chan, Ka Po

    2014-11-01

    Meditation is important in facilitating health. Pregnancy health has been shown to have significant consequences for infant behaviors. In view of limited studies on meditation and infant temperament, this study aims to explore the effects of prenatal meditation on these aspects. The conceptual framework was based on the postulation of positive relationships between prenatal meditation and infant health. A randomized control quantitative study was carried out at Obstetric Unit, Queen Elizabeth Hospital in Hong Kong. 64 pregnant Chinese women were recruited for intervention and 59 were for control. Outcome measures were cord blood cortisol, infant salivary cortisol, and Carey Infant Temperament Questionnaire. Cord blood cortisol level of babies was higher in the intervention group (p<0.01) indicates positive health status of the newborns verifies that prenatal meditation can influence fetal health. Carey Infant Temperament Questionnaire showed that the infants of intervention group have better temperament (p<0.05) at fifth month reflects the importance of prenatal meditation in relation to child health. Present study concludes the positive effects of prenatal meditation on infant behaviors and recommends that pregnancy care providers should provide prenatal meditation to pregnant women.

  2. Deformation parameters influencing prepreg tack

    SciTech Connect

    Ahn, K.J.; Seferis, J.C. ); Pelton, T.; Wilhelm, M. )

    1992-01-01

    A compression to tension apparatus and a methodology capable of measuring prepreg tack have been analyzed in detail in order to establish fundamental material and operating characteristics. Both intrinsic and extrinsic parameters influencing prepreg tack were identified and analyzed using commercially available carbon fiber/epoxy prepregs and mechanical testing equipment. Two different factors, (1) contact (or wetting) area of adjacent prepreg plies and (2) viscoelastic properties of the prepreg, were found to control prepreg tack. At low temperatures, contact area was the main deformation controlling step, while at high temperatures, the viscoelastic property of the prepreg was found to be dominant. Both interlaminar and intralaminar deformations were observed depending on the prepreg systems examined as well as the operating conditions of the test. In addition, hold time, hold pressure, loading rate, resin content, and out-time were also found to affect prepreg tack. Energy of separation, which may be viewed as a descriptor of prepreg tack, was observed to increase with increasing hold time, hold pressure, and loading rate. Energy of separation also showed a maximum value at a specific resin content for a specific prepreg system, while it decreased with increasing prepreg out-time due to prepreg surface characteristic change rather than bulk physical aging. Conclusively, it was observed that prepreg tack must be viewed as an extrinsic, bulk, but surface-sensitive, viscoelastic property which depends on material as well as operating conditions.

  3. SURFACE CHEMISTRY INFLUENCE IMPLANT BIOCOMPATIBILITY

    PubMed Central

    Thevenot, Paul; Hu, Wenjing; Tang, Liping

    2011-01-01

    Implantable medical devices are increasingly important in the practice of modern medicine. Unfortunately, almost all medical devices suffer to a different extent from adverse reactions, including inflammation, fibrosis, thrombosis and infection. To improve the safety and function of many types of medical implants, a major need exists for development of materials that evoked desired tissue responses. Because implant-associated protein adsorption and conformational changes thereafter have been shown to promote immune reactions, rigorous research efforts have been emphasized on the engineering of surface property (physical and chemical characteristics) to reduce protein adsorption and cell interactions and subsequently improve implant biocompatibility. This brief review is aimed to summarize the past efforts and our recent knowledge about the influence of surface functionality on protein:cell:biomaterial interactions. It is our belief that detailed understandings of bioactivity of surface functionality provide an easy, economic, and specific approach for the future rational design of implantable medical devices with desired tissue reactivity and, hopefully, wound healing capability. PMID:18393890

  4. Influence of weather on osteoarthritics.

    PubMed

    Laborde, J M; Dando, W A; Powers, M J

    1986-01-01

    This exploratory study examined the effects of selected weather variables on pain and pain-related stress in osteoarthritic subjects. Urban and rural dwelling arthritics who perceived that weather made their symptoms worse and those who did not were surveyed. Some persons with osteoarthritis in urban Chicago were more weather sensitive than their rural counterparts in Grand Forks, North Dakota. Multiple regression analysis showed that precipitation affected degree of pain for urban subjects who identified weather as a pain-generating factor; barometric pressure, relative humidity and sunshine were significant factors influencing pain-related stress. Wind speed correlated with pain and pain-related stress; relative humidity and precipitation correlated with pain-related stress for urban subjects who did not perceive weather as a problem. Specific weather variables were not identified as affecting rural subjects' pain. However, temperature and barometric pressure affected degree of pain-related stress in rural subjects who perceived weather as a problem. Subtle differences between Chicago urban and Grand Forks rural climates are reflected in arthritic subjects' degree of pain and their perception of pain-related stress.

  5. Factors influencing breath ammonia determination.

    PubMed

    Solga, Steven F; Mudalel, Matthew; Spacek, Lisa A; Lewicki, Rafal; Tittel, Frank; Loccioni, Claudio; Russo, Adolfo; Risby, Terence H

    2013-09-01

    Amongst volatile compounds (VCs) present in exhaled breath, ammonia has held great promise and yet it has confounded researchers due to its inherent reactivity. Herein we have evaluated various factors in both breath instrumentation and the breath collection process in an effort to reduce variability. We found that the temperature of breath sampler and breath sensor, mouth rinse pH, and mode of breathing to be important factors. The influence of the rinses is heavily dependent upon the pH of the rinse. The basic rinse (pH 8.0) caused a mean increase of the ammonia concentration by 410 ± 221 ppb. The neutral rinse (pH 7.0), slightly acidic rinse (pH 5.8), and acidic rinse (pH 2.5) caused a mean decrease of the ammonia concentration by 498 ± 355 ppb, 527 ± 198 ppb, and 596 ± 385 ppb, respectively. Mode of breathing (mouth-open versus mouth-closed) demonstrated itself to have a large impact on the rate of recovery of breath ammonia after a water rinse. Within 30 min, breath ammonia returned to 98 ± 16% that of the baseline with mouth open breathing, while mouth closed breathing allowed breath ammonia to return to 53 ± 14% of baseline. These results contribute to a growing body of literature that will improve reproducibly in ammonia and other VCs.

  6. Wind-influenced projectile motion

    NASA Astrophysics Data System (ADS)

    Bernardo, Reginald Christian; Perico Esguerra, Jose; Day Vallejos, Jazmine; Jerard Canda, Jeff

    2015-03-01

    We solved the wind-influenced projectile motion problem with the same initial and final heights and obtained exact analytical expressions for the shape of the trajectory, range, maximum height, time of flight, time of ascent, and time of descent with the help of the Lambert W function. It turns out that the range and maximum horizontal displacement are not always equal. When launched at a critical angle, the projectile will return to its starting position. It turns out that a launch angle of 90° maximizes the time of flight, time of ascent, time of descent, and maximum height and that the launch angle corresponding to maximum range can be obtained by solving a transcendental equation. Finally, we expressed in a parametric equation the locus of points corresponding to maximum heights for projectiles launched from the ground with the same initial speed in all directions. We used the results to estimate how much a moderate wind can modify a golf ball’s range and suggested other possible applications.

  7. Solar Influence on Future Climate

    NASA Astrophysics Data System (ADS)

    Arsenovic, Pavle; Stenke, Andrea; Rozanov, Eugene; Peter, Thomas

    2015-04-01

    Global warming is one of the main threats to mankind. There is growing evidence that anthropogenic greenhouse gases have become the dominant factor, however natural factors such as solar variability cannot be neglected. Sun is a variable star; its activity varies in regular 11-years solar cycles. Longer periods of decreased solar activity are called Grand Solar Minima, which have stronger impact on terrestrial climate. Another natural factor related with solar activity are energetic particles. They can ionize neutral molecules in upper atmosphere and produce NOx and HOx which deplete ozone. We investigate the effect of proposed Grand Solar Minimum in 21st and 22nd century on terrestrial climate and ozone layer. The simulations are performed with different solar forcing scenarios for period of 200 years (2000-2200) using global chemistry-climate model coupled with ocean model (SOCOL-MPIOM). We also deal with problem of representation of middle range energy electrons (30-300 keV) in the model and investigation of their influence on climate.

  8. [Erasmian influences among renaissance physicians].

    PubMed

    de Micheli, Alfredo

    2002-01-01

    The fundamental aspects of Erasmus's ethic humanism consisted of ideals of universal peace and tolerance. These ideals are exposed in the great works of his maturity Colloquia and Adagia read and meditated on by renaissance physicians in England, Spain, Germany, Italy, and also in the New Spain. Erasmus's readers were learned and numerous. Among his pupils and supporters in Spain were humanist physicians of Madrid such as Doctors Suárez and Juan de Jarava. Other supporters were in the group of the Sevillian physicians and naturalists. Among the Erasmist physicians, residing in other regions was doctor Andrés Laguna, who translated into Spanish the Dioscorides treatise on medical botany. Many physicians living in New Spain owned copies of Erasmian works, such as Doctors Pedro López (the second) and Juan de la Fuente, who was in charge of the first medical chair at the University of Mexico. The protophysician Francisco Hernández, in response to a petition of Archbishop Pedro Moya de Contreras, wrote a Christian catechism of Erasmian influence, destined for humanists in NewSpain. As asserted by Johan Huizinga, Erasmus was the sole humanist who really wrote for everyone, i.e. for all cultured people.

  9. Factors influencing perceived angular velocity

    NASA Technical Reports Server (NTRS)

    Kaiser, Mary K.; Calderone, Jack B.

    1991-01-01

    Angular velocity perception is examined for rotations both in depth and in the image plane and the influence of several object properties on this motion parameter is explored. Two major object properties are considered, namely, texture density which determines the rate of edge transitions for rotations in depth, i.e., the number of texture elements that pass an object's boundary per unit of time, and object size which determines the tangential linear velocities and 2D image velocities of texture elements for a given angular velocity. Results of experiments show that edge-transition rate biased angular velocity estimates only when edges were highly salient. Element velocities had an impact on perceived angular velocity; this bias was associated with 2D image velocity rather than 3D tangential velocity. Despite these biases judgements were most strongly determined by the true angular velocity. Sensitivity to this higher order motion parameter appeared to be good for rotations both in depth (y-axis) and parallel to the line of sight (z-axis).

  10. Factors influencing healthcare service quality

    PubMed Central

    Mosadeghrad, Ali Mohammad

    2014-01-01

    Background: The main purpose of this study was to identify factors that influence healthcare quality in the Iranian context. Methods: Exploratory in-depth individual and focus group interviews were conducted with 222 healthcare stakeholders including healthcare providers, managers, policy-makers, and payers to identify factors affecting the quality of healthcare services provided in Iranian healthcare organisations. Results: Quality in healthcare is a production of cooperation between the patient and the healthcare provider in a supportive environment. Personal factors of the provider and the patient, and factors pertaining to the healthcare organisation, healthcare system, and the broader environment affect healthcare service quality. Healthcare quality can be improved by supportive visionary leadership, proper planning, education and training, availability of resources, effective management of resources, employees and processes, and collaboration and cooperation among providers. Conclusion: This article contributes to healthcare theory and practice by developing a conceptual framework that provides policy-makers and managers a practical understanding of factors that affect healthcare service quality. PMID:25114946

  11. Physiological factors influencing capillary growth.

    PubMed

    Egginton, S

    2011-07-01

    (1) Angiogenesis (growth of new capillaries from an existing capillary bed) may result from a mismatch in microvascular supply and metabolic demand (metabolic error signal). Krogh examined the distribution and number of capillaries to explore the correlation between O(2) delivery and O(2) consumption. Subsequently, the heterogeneity in angiogenic response within a muscle has been shown to reflect either differences in fibre type composition or mechanical load. However, local control leads to targetted angiogenesis in the vicinity of glycolytic fibre types following muscle stimulation, or oxidative fibres following endurance training, while heterogeneity of capillary spacing is maintained during ontogenetic growth. (2) Despite limited microscopy resolution and lack of specific markers, Krogh's interest in the structure of the capillary wall paved the way for understanding the mechanisms of capillary growth. Angiogenesis may be influenced by the response of perivascular or stromal cells (fibroblasts, macrophages and pericytes) to altered activity, likely acting as a source for chemical signals modulating capillary growth such as vascular endothelial growth factor. In addition, haemodynamic factors such as shear stress and muscle stretch play a significant role in adaptive remodelling of the microcirculation. (3) Most indices of capillarity are highly dependent on fibre size, resulting in possible bias because of scaling. To examine the consequences of capillary distribution, it is therefore helpful to quantify the area of tissue supplied by individual capillaries. This allows the spatial limitations inherent in most models of tissue oxygenation to be overcome generating an alternative approach to Krogh's tissue cylinder, the capillary domain, to improve descriptions of intracellular oxygen diffusion. © 2010 The Author. Acta Physiologica © 2010 Scandinavian Physiological Society.

  12. Influence of antidepressants on hemostasis

    PubMed Central

    Halperin, Demian; Reber, Guido

    2007-01-01

    Antidepressants, particularly selective serotonin reuptake inhibitors (SSRIs), are widely used for the treatment of depression and anxious disorders. The observation that depression is an independent risk factor for cardiovascular mortality and morbidity in patients with ischemic heart disease, the assessment of the central role of serotonin in pathophysiological mechanisms of depression, and reports of cases of abnormal bleeding associated with antidepressant therapy have led to investigations of the influence of antidepressants on hemostasis markers. In this review, we summarize data regarding modifications of these markers, drawn from clinical studies and case reports. We observed an association between the type of antidepressant drug and the number of abnormal bleeding case reports, with or without modifications of hemostasis markers. Drugs with the highest degree of serotonin reuptake inhibition - fluoxetine, paroxetine, and sertraline - are more frequently associated with abnormal bleeding and modifications of hemostasis markers. The most frequent hemostatic abnormalities are decreased platelet aggregability and activity, and prolongation of bleeding time. Patients with a history of coagulation disorders, especially suspected or documented thrombocytopenia or platelet disorder, should be monitored in case of prescription of any serotonin reuptake inhibitor (SRI). Platelet dysfunction, coagulation disorder, and von Willebrand disease should be sought in any case of abnormal bleeding occurring during treatment with an SRI. Also, a non-SSRI antidepressant should be favored over an SSRI or an SRI in such a context. Considering the difficulty in performing platelet aggregation tests, which are the most sensitive in SRI-associated bleeding, and the low sensitivity of hemostasis tests when performed in case of uncomplicated bleeding in the general population, establishing guidelines for the assessment of SRI-associated bleeding complications remains a challenge

  13. Can tides influence volcanic eruptions?

    NASA Astrophysics Data System (ADS)

    Girona, T.; Huber, C.

    2015-12-01

    The possibility that the Moon-Sun gravitational force can affect terrestrial volcanoes and trigger eruptions is a controversial issue that has been proposed since ancient times, and that has been widely debated during the last century. The controversy arises mainly from two reasons. First, the days of initiation of eruptions are not well known for many volcanoes, and thus a robust statistical comparison with tidal cycles cannot be performed for many of them. Second, the stress changes induced by tides in the upper crust are very small (10-3 MPa) compared to the tensile strength of rocks (~ 10-1-10 MPa), and hence the mechanism by which tidal stresses might trigger eruptions is unclear. In this study, we address these issues for persistently degassing volcanoes, as they erupt frequently and thus the initiation time of a significant number of eruptions (>30) is well known in several cases (9). In particular, we find that the occurrence of eruptions within ±2 days from neap tides (first and third quarter moon) is lower than 34% (e.g., 29% for Etna, Italy; 28% for Merapi, Indonesia), which is the value expected if eruptions occur randomly with no external influence. To understand this preference for erupting far away from neap tides, we have developed a new lumped-parameter model that accounts for the deformation of magma reservoirs, a partially open conduit, and a gas layer where bubbles accumulate beneath volcanic craters before being released. We demonstrate that this system reservoir-conduit-gas layer acts as an amplifier of the tidal stresses, such that, when a volcano approaches to a critical state, the gas overpressure beneath the crater can reach up to several MPa more during a spring tide (full and new moon) than during a neap tide. This amplification mechanism can explain why active volcanoes are sensitive to the moon cycles.

  14. Relative Influence of Professional Counseling Journals

    ERIC Educational Resources Information Center

    Fernando, Delini M.; Barrio Minton, Casey A.

    2011-01-01

    The authors used social network analysis of citation data to study the flow of information and relative influence of 17 professional counseling journals. Although the "Journal of Counseling & Development" ranked very highly in all measures of journal influence, several division journals emerged as key players in the flow of information within the…

  15. Nurses' policy influence: A concept analysis.

    PubMed

    Arabi, Akram; Rafii, Forough; Cheraghi, Mohammad Ali; Ghiyasvandian, Shahrzad

    2014-05-01

    Nurses' influence on health policy protects the quality of care by access to required recourses and opportunities. This is a new and important concept for nursing; however, research studies on policy influence of nurses in health care sector are lacking a basic conceptual understanding of what this concept represents. The aim of this paper is to clarify the concept of nurses' policy influence and to propose the definition of this concept, considering the context of Iran. The eight stages of Walker and Avant approach was used to guide this concept analysis. Various databases and internet engines were searched to find all related information about the concept. Textbooks were also searched manually. English language literature reports published between 1990 and 2012 were reviewed. Based on the analysis undertaken, nurses' policy influence is nurses' ability in influencing decisions and affairs related to health through political knowledge, effective communication, and collaboration with other members of the health team, which results in the improvement of nurses' job environment and increases patient outcomes. This is a dynamic process situated on a spectrum and is accompanied with nurses' knowledge, competency, power, and advocacy, and also their ability to change. Nurses have individual views on health care issues and influence health care policies in different ways. With a common understanding of nurses' policy influence as a concept, nurses will recognize the importance of policy making in the health sector and their influence on this process and also on patients' outcomes.

  16. Perceptions of Advertising Influence on Broadcast News.

    ERIC Educational Resources Information Center

    Brown, Hubert W.; Barnes, Beth E.

    2001-01-01

    Finds that while students (studying broadcast journalism or advertising) and practitioners (station news directors and agency media directors) were in agreement on the majority of opinion statements discussing advertising's influence on broadcast news content, except students were less bothered by advertising's influence on news content than were…

  17. The Influence of Notches Under Static Stress

    NASA Technical Reports Server (NTRS)

    Matthaes, K

    1938-01-01

    From the described experiments it is seen that notches are a potential source of strength decrease even under static stress, which the designer must take into consideration. Section I is a general treatment of notch influence under the various types of stresses. Section II treats the influence of notches in thin sheet as is used in airplane construction.

  18. Factors that Influence Participation in Online Learning

    ERIC Educational Resources Information Center

    Vonderwell, Selma; Zachariah, Sajit

    2005-01-01

    This study explored what factors influenced learner participation in two sections of a graduate online course at a Midwestern university. Findings indicated that online learner participation and patterns of participation are influenced by the following factors: technology and interface characteristics, content area experience, student roles and…

  19. The Influence of Poverty on Achievement

    ERIC Educational Resources Information Center

    Tienken, Christopher H.

    2012-01-01

    Without a doubt, poverty has a negative influence on student achievement, especially when achievement is measured by state-mandated standardized tests. However, some bureaucrats, such as state commissioners of education and even state governors, continue to downplay the influence of poverty on student achievement. New Jersey's Governor Chris…

  20. Genetic and Environmental Influences on Adolescent Attachment

    ERIC Educational Resources Information Center

    Fearon, Pasco; Shmueli-Goetz, Yael; Viding, Essi; Fonagy, Peter; Plomin, Robert

    2014-01-01

    Background: Twin studies consistently point to limited genetic influence on attachment security in the infancy period, but no study has examined whether this remains the case in later development. This study presents the findings from a twin study examining the relative importance of genetic and environmental influences on attachment in…

  1. How Friends Influence Adolescents' Adjustment to School.

    ERIC Educational Resources Information Center

    Berndt, Thomas J.; Keefe, Keunho

    A short-term longitudinal study investigated theoretical perspectives on friends' influences and compared the influence of a student's closest friend with that of several close friends. Participants were 297 seventh and eighth graders in junior high schools in small towns or rural areas adjacent to a medium-sized city. Measures obtained in the…

  2. Relative Influence of Professional Counseling Journals

    ERIC Educational Resources Information Center

    Fernando, Delini M.; Barrio Minton, Casey A.

    2011-01-01

    The authors used social network analysis of citation data to study the flow of information and relative influence of 17 professional counseling journals. Although the "Journal of Counseling & Development" ranked very highly in all measures of journal influence, several division journals emerged as key players in the flow of information within the…

  3. Natal Influences and Twin Differences: Draft.

    ERIC Educational Resources Information Center

    Van den Daele, Leland D.

    1972-01-01

    A classification of natal influences is proposed with a model of their operation. Natal influences affect maternal capacity, maternal load, and maternal efficiency. Since maternal load is increased in twin pregnancy, results of twin studies must be generalized with caution. The method of co-twin control is exemplified by examination of a small…

  4. 16 CFR 1107.24 - Undue influence.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 16 Commercial Practices 2 2014-01-01 2014-01-01 false Undue influence. 1107.24 Section 1107.24 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION CONSUMER PRODUCT SAFETY ACT REGULATIONS TESTING AND LABELING PERTAINING TO PRODUCT CERTIFICATION Certification of Children's Products § 1107.24 Undue influence...

  5. 16 CFR 1107.24 - Undue influence.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 16 Commercial Practices 2 2013-01-01 2013-01-01 false Undue influence. 1107.24 Section 1107.24 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION CONSUMER PRODUCT SAFETY ACT REGULATIONS TESTING AND LABELING PERTAINING TO PRODUCT CERTIFICATION Certification of Children's Products § 1107.24 Undue influence...

  6. 16 CFR 1107.24 - Undue influence.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 16 Commercial Practices 2 2012-01-01 2012-01-01 false Undue influence. 1107.24 Section 1107.24 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION CONSUMER PRODUCT SAFETY ACT REGULATIONS TESTING AND LABELING PERTAINING TO PRODUCT CERTIFICATION Certification of Children's Products § 1107.24 Undue influence...

  7. Sociocultural Influences on Brazilian Children's Drawings.

    ERIC Educational Resources Information Center

    Stokrocki, Mary

    2000-01-01

    Reports on insights about sociocultural influences on Brazilian children's drawings, using visual anthropology to examine children's drawings that depicted what they like to do. Discusses visual anthropology, provides information on Brazilian educational influences, and presents the context and findings of the study. (CMK)

  8. The Influence of Poverty on Achievement

    ERIC Educational Resources Information Center

    Tienken, Christopher H.

    2012-01-01

    Without a doubt, poverty has a negative influence on student achievement, especially when achievement is measured by state-mandated standardized tests. However, some bureaucrats, such as state commissioners of education and even state governors, continue to downplay the influence of poverty on student achievement. New Jersey's Governor Chris…

  9. American Influence on Okinawan Culture before 1972.

    ERIC Educational Resources Information Center

    Trafton, Terry

    The Ryukyu Islands form a chain stretching from the southernmost point of mainland Japan to the northern tip of Taiwan. The largest and most important of these islands is Okinawa. This paper documents the influence of other nations and cultures upon the Okinawan culture, and focuses upon U.S. cultural influence. In the mid-nineteenth century,…

  10. Nonmetropolitan Migration: The Influence of Neglected Variables.

    ERIC Educational Resources Information Center

    Cook, Annabel Kirschner

    1987-01-01

    Compares influence of employment growth/diversity, commuting, retirement migration, income, unemployment, age structure, and adjacency with influence of nonfarm self-employment and percentage of labor force that is female on recent declines in nonmetropolitan growth rates. Suggests last two variables are more important determinants of…

  11. Influence of Educational Attainment on Consumption

    ERIC Educational Resources Information Center

    Zhang, Xuemin; He, Youning

    2007-01-01

    In market economy, man is both the essential productive factor and the consuming subject. Education promotes the two aspects. As shown by investigations on the influence of educational attainment on consumption, education has great influences on people's consumption level, consumption structure, consumption modes and consumption concepts. The…

  12. Hannelore Wass: Professional Influences and Legacies.

    PubMed

    Corr, Charles A

    2015-01-01

    This article offers a reflection on the professional influence of Dr. Hannelore Wass on the author's introduction to and work in the field of death, dying, and bereavement. At the same time, it also offers comments on her broader influence on and legacies left to others who work in this field.

  13. Geodesics and Acceleration in Influence Theory

    NASA Astrophysics Data System (ADS)

    Walsh, James; Knuth, Kevin

    Influence theory is concerned with a foundational approach where it is assumed that particles influence one another in a discrete one-to-one fashion. This results in a partially ordered set of influence events, called the influence network, where particles are represented by totally ordered chains of events. Information physics considers physical laws to result from consistent quantification of physical phenomena. Knuth and Bahreyni (2014) demonstrated that the mathematics of spacetime emerges from consistent quantification of influence events by embedded coordinated observers. Knuth (2014) showed that in 1 +1 dimensions observer-based predictions about a free (uninfluenced) particle result in the Dirac equation. Here, we show that when a particle in 1 +1 dimensions is influenced, it is uniquely and consistently described in terms of relativistic acceleration for constant rate of influence and in general obeys equations of the form of the geodesic equations of general relativity. This suggests that Influence Theory can also account for forces (like gravity), which give rise to well-known relativistic effects such as time dilation.

  14. Sociocultural Influences on Brazilian Children's Drawings.

    ERIC Educational Resources Information Center

    Stokrocki, Mary

    2000-01-01

    Reports on insights about sociocultural influences on Brazilian children's drawings, using visual anthropology to examine children's drawings that depicted what they like to do. Discusses visual anthropology, provides information on Brazilian educational influences, and presents the context and findings of the study. (CMK)

  15. Perceptions of Advertising Influence on Broadcast News.

    ERIC Educational Resources Information Center

    Brown, Hubert W.; Barnes, Beth E.

    2001-01-01

    Finds that while students (studying broadcast journalism or advertising) and practitioners (station news directors and agency media directors) were in agreement on the majority of opinion statements discussing advertising's influence on broadcast news content, except students were less bothered by advertising's influence on news content than were…

  16. Substitute or Complement?: Spousal Influence on Volunteering

    ERIC Educational Resources Information Center

    Rotolo, Thomas; Wilson, John

    2006-01-01

    Social scientists have documented the influence of family statuses on volunteering, ignoring intrafamily effects. Using newly issued data from the Current Population Survey on the volunteer behavior of 19,626 American couples, we test two competing theories concerning spousal influences on volunteering. Substitution theory predicts that spouses…

  17. Genetic and Environmental Influences on Adolescent Attachment

    ERIC Educational Resources Information Center

    Fearon, Pasco; Shmueli-Goetz, Yael; Viding, Essi; Fonagy, Peter; Plomin, Robert

    2014-01-01

    Background: Twin studies consistently point to limited genetic influence on attachment security in the infancy period, but no study has examined whether this remains the case in later development. This study presents the findings from a twin study examining the relative importance of genetic and environmental influences on attachment in…

  18. Nurses’ policy influence: A concept analysis

    PubMed Central

    Arabi, Akram; Rafii, Forough; Cheraghi, Mohammad Ali; Ghiyasvandian, Shahrzad

    2014-01-01

    Background: Nurses’ influence on health policy protects the quality of care by access to required recourses and opportunities. This is a new and important concept for nursing; however, research studies on policy influence of nurses in health care sector are lacking a basic conceptual understanding of what this concept represents. The aim of this paper is to clarify the concept of nurses’ policy influence and to propose the definition of this concept, considering the context of Iran. Materials and Methods: The eight stages of Walker and Avant approach was used to guide this concept analysis. Various databases and internet engines were searched to find all related information about the concept. Textbooks were also searched manually. English language literature reports published between 1990 and 2012 were reviewed. Results: Based on the analysis undertaken, nurses’ policy influence is nurses’ ability in influencing decisions and affairs related to health through political knowledge, effective communication, and collaboration with other members of the health team, which results in the improvement of nurses’ job environment and increases patient outcomes. This is a dynamic process situated on a spectrum and is accompanied with nurses’ knowledge, competency, power, and advocacy, and also their ability to change. Conclusions: Nurses have individual views on health care issues and influence health care policies in different ways. With a common understanding of nurses’ policy influence as a concept, nurses will recognize the importance of policy making in the health sector and their influence on this process and also on patients’ outcomes. PMID:24949073

  19. Brain Substrates of Recovery from Misleading Influence

    PubMed Central

    Dudai, Yadin; Dolan, Raymond J.; Sharot, Tali

    2014-01-01

    Humans are strongly influenced by their environment, a dependence that can lead to errors in judgment. Although a rich literature describes how people are influenced by others, little is known regarding the factors that predict subsequent rectification of misleading influence. Using a mediation model in combination with brain imaging, we propose a model for the correction of misinformation. Specifically, our data suggest that amygdala modulation of hippocampal mnemonic representations, during the time of misleading social influence, is associated with reduced subsequent anterior–lateral prefrontal cortex activity that reflects correction. These findings illuminate the process by which erroneous beliefs are, or fail to be, rectified and highlight how past influence constrains subsequent correction. PMID:24899698

  20. Influence analysis in quantitative trait loci detection

    PubMed Central

    Dou, Xiaoling; Kuriki, Satoshi; Maeno, Akiteru; Takada, Toyoyuki; Shiroishi, Toshihiko

    2014-01-01

    This paper presents systematic methods for the detection of influential individuals that affect the log odds (LOD) score curve. We derive general formulas of influence functions for profile likelihoods and introduce them into two standard quantitative trait locus detection methods—the interval mapping method and single marker analysis. Besides influence analysis on specific LOD scores, we also develop influence analysis methods on the shape of the LOD score curves. A simulation-based method is proposed to assess the significance of the influence of the individuals. These methods are shown useful in the influence analysis of a real dataset of an experimental population from an F2 mouse cross. By receiver operating characteristic analysis, we confirm that the proposed methods show better performance than existing diagnostics. PMID:24740424

  1. Influence analysis in quantitative trait loci detection.

    PubMed

    Dou, Xiaoling; Kuriki, Satoshi; Maeno, Akiteru; Takada, Toyoyuki; Shiroishi, Toshihiko

    2014-07-01

    This paper presents systematic methods for the detection of influential individuals that affect the log odds (LOD) score curve. We derive general formulas of influence functions for profile likelihoods and introduce them into two standard quantitative trait locus detection methods-the interval mapping method and single marker analysis. Besides influence analysis on specific LOD scores, we also develop influence analysis methods on the shape of the LOD score curves. A simulation-based method is proposed to assess the significance of the influence of the individuals. These methods are shown useful in the influence analysis of a real dataset of an experimental population from an F2 mouse cross. By receiver operating characteristic analysis, we confirm that the proposed methods show better performance than existing diagnostics. © 2014 The Author. Biometrical Journal published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Open to Influence: What Counts as Academic Influence in Scholarly Networked "Twitter" Participation

    ERIC Educational Resources Information Center

    Stewart, Bonnie

    2015-01-01

    Within the academy, signals of a scholar's academic influence are made manifest in indices like the "h"-index, which rank output. In open scholarly networks, however, signals of influence are less codified, and the ways in which they are enacted and understood have yet to be articulated. Yet the influence scholars cultivate in open…

  3. Open to Influence: What Counts as Academic Influence in Scholarly Networked "Twitter" Participation

    ERIC Educational Resources Information Center

    Stewart, Bonnie

    2015-01-01

    Within the academy, signals of a scholar's academic influence are made manifest in indices like the "h"-index, which rank output. In open scholarly networks, however, signals of influence are less codified, and the ways in which they are enacted and understood have yet to be articulated. Yet the influence scholars cultivate in open…

  4. FINAL REPORT ON THE AQUATIC MERCURY ASSESSMENT STUDY

    SciTech Connect

    Halverson, N

    2008-09-30

    showed that determination of representative BAFs for large rivers requires the collection of large numbers of fish and aqueous methylmercury samples over at least one complete seasonal cycle from the entire area and all habitats to be represented by the TMDL. The third study concerned the use of clams as an indicator of the influence of SRS discharges on mercury levels in Savannah River biota. Mercury levels were compared in Asiatic clams (Corbicula fluminea) collected from the discharge plumes and just upstream of the mouths of SRS creeks and two creeks located downstream from the SRS. Asiatic clams were selected for study because their relatively sedentary behavior made them a better indicator of local mercury exposure than mobile organisms.

  5. Influencing Safety in Australian Agriculture and Fisheries.

    PubMed

    McBain-Rigg, Kristin E; Franklin, Richard C; King, Jemma C; Lower, Tony

    2017-01-01

    Improving the health and safety of those working in Australian agriculture and fishery industries is a recognized priority area for preventative activities. With Australian agricultural industries being among the nation's most dangerous workplaces, there is a need for action. While there are currently known solutions, their implementation is limited. Influential agents, i.e., people who can influence others, are important for helping engender action to enact solutions into practice. This study examines agents that influence safety behavior either negatively (barriers) or positively (facilitators), in the Australian agriculture and fishery industries. Focus groups were conducted with producers and industry representatives. Thematic analysis identified barriers and facilitators to improve health and safety. These were assessed against the Socioecological Model, which considers the various, and often intersecting, human (intrapersonal, i.e. values and attitudes, peers, familial, and cultural) factors influencing safety behavior. Seven categories of human influences were identified: self, peers, family, intergenerational change, industry agents, government agents, and other. Peers (including direct managers) and family were seen to be direct influencers. Individuals signal to others that safety is valued and important. This is reinforced by experience, skill, attitudes, and behavior. Safety practice knowledge acquisition occurred via the family unit, specific training, industry, or knowledge transfer between industries. Government influence predominately focused on legislation and while the source of this influence is distant, it does influence behavior. There is a need to support comprehensive programs. These should include strengthening relationships via peer-to-peer networking, sharing information about safety initiatives, appropriate legislation, and enhancing leadership of all influencers with regard to safety.

  6. Ranked Levels of Influence Model: Selecting Influence Techniques to Minimize IT Resistance

    PubMed Central

    Bartos, Christa E.; Butler, Brian S.; Crowley, Rebecca S.

    2010-01-01

    Implementation of electronic health records (EHR), particularly computerized physician/provider order entry systems (CPOE), is often met with resistance. Influence presented at the right time, in the right manner, may minimize resistance or at least limit the risk of complete system failure. Combining established theories on power, influence tactics, and resistance, we developed the Ranked Levels of Influence model. Applying it to documented examples of EHR/CPOE failures at Cedars-Sinai and Kaiser Permanente in Hawaii, we evaluated the influence applied, the resistance encountered, and the resulting risk to the system implementation. Using the Ranked Levels of Influence model as a guideline, we demonstrate that these system failures were associated with the use of hard influence tactics that resulted in higher levels of resistance. We suggest that when influence tactics remain at the soft tactics level, the level of resistance stabilizes or de-escalates and the system can be saved. PMID:20176135

  7. The Power of Influence: School Nurse Stories.

    PubMed

    Mazyck, Donna; Cellucci, Margaret; Largent, Piper

    2015-07-01

    School nurses have influence, and this influence is ignited with school nurse stories. School nurses must tell school staff, leaders, families, and students what they do to help students access their education. School boards, city councils, and legislators need to know the knowledge, skills, and judgment school nurses use daily. NASN understands that school nurses benefit from a "how to" kit and has developed tools to empower school nurses in advocating for their important role in supporting the health and learning of students. This article provides an overview this newly developed electronic toolkit while at the same time reinforcing the power of influence when sharing your stories. © 2015 The Author(s).

  8. Arsenic in benthic bivalves of San Francisco Bay and the Sacramento/San Joaquin River Delta.

    PubMed

    Johns, C; Luoma, S N

    1990-11-01

    Arsenic concentrations were determined in fine-grained, oxidized, surface sediments and in two benthic bivalves, Corbicula sp. and Macoma balthica, within San Francisco Bay, the Sacramento/San Joaquin River Delta, and selected rivers not influenced by urban or industrial activity. Arsenic concentrations in all samples were characteristic of values reported for uncontaminated estuaries. Small temporal fluctuations and low arsenic concentrations in bivalves and sediments suggest that most inputs of arsenic are likely to be minor and arsenic contamination is not widespread in the Bay.

  9. [Distant mental influence on living organisms].

    PubMed

    Bonilla, Ernesto

    2013-12-01

    This article reviews studies of distant mental influence on living organisms, including mental suggestions of sleeping and awakening, mental influence at long distances, mental interactions with remote biological systems, mental effects on physiological activity and the sense of being stared at. Significant effects of distant mental influence have been shown in several randomized controlled trials in humans, animals, plants, bacteria and cells in the laboratory. Although distant mental influence on living organisms appears to contradict our ordinary sense of reality and the laws defined by conventional science, several hypotheses have been proposed to explain the observed effects; they include skeptical, signal transfer, field, multidimensional space/time and quantum mechanics hypotheses. In conclusion, as the progress of physics continues to expand our comprehension of reality, a rational explanation for distant mind-matter interaction will emerge and, as history has shown repeatedly, the supernatural events will evolve into paranormal and then, into normal ones, as the scientific frontiers expand.

  10. Follow your heart: Emotion adaptively influences perception

    PubMed Central

    Stefanucci, Jeanine K.; Gagnon, Kyle T.; Lessard, David A.

    2011-01-01

    The current review introduces a new program of research that suggests the perception of spatial layout is influenced by emotions. Though perceptual systems are often described as closed and insulated, this review presents research suggesting that a variety of induced emotions (e.g., fear, disgust, sadness) can produce changes in vision and audition. Thus, the perceptual system may be highly interconnected, allowing emotional information to influence perceptions that, in turn, influence cognition. The body of work presented here also suggests that emotion-based changes in perception help us solve particular adaptive problems because emotion does not change all perceptions of the world. Taking the adaptive significance of emotion into account allows us to make predictions about when and how emotion influences perception. PMID:21731579

  11. Estrogen May Influence Women's Depression Risk

    MedlinePlus

    ... news/fullstory_167353.html Estrogen May Influence Women's Depression Risk Early menstruation, more frequent periods seem to ... reproductive years may have a lower risk of depression, a new study finds. Previous research has suggested ...

  12. Hotel Housekeeping Work Influences on Hypertension Management

    PubMed Central

    Sanon, Marie-Anne

    2013-01-01

    Background Characteristics of hotel housekeeping work increase the risk for hypertension development. Little is known about the influences of such work on hypertension management. Methods For this qualitative study, 27 Haitian immigrant hotel housekeepers from Miami-Dade County, FL were interviewed. Interview transcripts were analyzed with the assistance of the Atlas. ti software for code and theme identification. Results Influences of hotel housekeeping work on hypertension management arose both at the individual and system levels. Factors at the individual level included co-worker dynamics and maintenance of transmigrant life. Factors at the system level included supervisory support, workload, work pace, and work hiring practices. No positive influences were reported for workload and hiring practices. Conclusions Workplace interventions may be beneficial for effective hypertension management among hotel housekeepers. These work influences must be considered when determining effective methods for hypertension management among hotel housekeepers. PMID:23775918

  13. Hotel housekeeping work influences on hypertension management.

    PubMed

    Sanon, Marie-Anne

    2013-12-01

    Characteristics of hotel housekeeping work increase the risk for hypertension development. Little is known about the influences of such work on hypertension management. For this qualitative study, 27 Haitian immigrant hotel housekeepers from Miami-Dade County, FL were interviewed. Interview transcripts were analyzed with the assistance of the Atlas.ti software for code and theme identification. Influences of hotel housekeeping work on hypertension management arose both at the individual and system levels. Factors at the individual level included co-worker dynamics and maintenance of transmigrant life. Factors at the system level included supervisory support, workload, work pace, and work hiring practices. No positive influences were reported for workload and hiring practices. Workplace interventions may be beneficial for effective hypertension management among hotel housekeepers. These work influences must be considered when determining effective methods for hypertension management among hotel housekeepers. © 2013 Wiley Periodicals, Inc.

  14. Parental Influence on Young People's Career Development.

    ERIC Educational Resources Information Center

    Otto, Luther B.; Call, Vaughn R. A.

    1985-01-01

    Describes theory and research on parental influence on young people's career development and highlights an important implication of this relationship for career counseling. The authors discuss a seminar that helps parents help their children choose careers. (CT)

  15. Cultural and Technological Influences: An Introduction.

    ERIC Educational Resources Information Center

    Shank, Russell

    1992-01-01

    Discusses cultural and technological influences in the management of human resources in the research library and their impact on individual rights and responsibilities, division of labor, supervision, educational requirements, and job stress. (23 references) (EA)

  16. Latina mothers' influences on child appetite regulation

    USDA-ARS?s Scientific Manuscript database

    Parents influence child weight through interactions that shape the development of child eating behaviors. In this study we examined the association between maternal autonomy promoting serving practices and child appetite regulation. We predicted that maternal autonomy promoting serving practices wou...

  17. Diseases and Conditions That Influence Fertility

    MedlinePlus

    ... and Conditions That Influence Fertility Skip sharing on social media links Share this: Page Content Many different health issues can affect a woman's ability to get pregnant. Some of the more common ...

  18. Factors that Influence Adolescents to Smoke.

    ERIC Educational Resources Information Center

    Smith, Karen H.; Stutts, Mary Ann

    1999-01-01

    A survey of the factors that influence adolescents (n=246) to smoke found that family smoking behavior, peer pressure, and prior beliefs were more important in predicting smoking level than were advertising and antismoking information. (Author/JOW)

  19. Region effects influence local tree species diversity.

    PubMed

    Ricklefs, Robert E; He, Fangliang

    2016-01-19

    Global patterns of biodiversity reflect both regional and local processes, but the relative importance of local ecological limits to species coexistence, as influenced by the physical environment, in contrast to regional processes including species production, dispersal, and extinction, is poorly understood. Failure to distinguish regional influences from local effects has been due, in part, to sampling limitations at small scales, environmental heterogeneity within local or regional samples, and incomplete geographic sampling of species. Here, we use a global dataset comprising 47 forest plots to demonstrate significant region effects on diversity, beyond the influence of local climate, which together explain more than 92% of the global variation in local forest tree species richness. Significant region effects imply that large-scale processes shaping the regional diversity of forest trees exert influence down to the local scale, where they interact with local processes to determine the number of coexisting species.

  20. Factors that influence women's dispositions toward science

    NASA Astrophysics Data System (ADS)

    Atria, Catherine Graczyk

    Females have been underrepresented in the study of science and science careers for decades although advancements have been made in closing this gender gap, the gap persists particularly in the physical sciences. Variables which influence a woman's desire to pursue and maintain a science course of study and career must be discovered. The United States lags behind other industrialized countries in the fields of science, math, and engineering. Females comprise an estimated half of the population; their potential contributions cannot be ignored or overlooked. This retrospective research study explores the personal experiences of ten women enrolled in science majors, with science related career plans. The goal of this study is to describe the factors that influence the participants' interest in science. The findings, the effect of science coursework, science teachers' personality and manner, other influential educational personnel, role models and mentors, external influences exclusive of school, parental influence, locus of control and positive attitudes toward science confirm what other researchers have found.

  1. Cultural and Technological Influences: An Introduction.

    ERIC Educational Resources Information Center

    Shank, Russell

    1992-01-01

    Discusses cultural and technological influences in the management of human resources in the research library and their impact on individual rights and responsibilities, division of labor, supervision, educational requirements, and job stress. (23 references) (EA)

  2. INFLUENCE OF MACROMOLECULES ON CHEMICAL TRANSPORT

    EPA Science Inventory

    Macromolecules in the pore fluid influence the mobility of hydrophobic compounds through soils. his study evaluated the significance of macromolecules in facilitating chemical transport under laboratory conditions. Partition coefficients between 14C-labeled hexachlorobenzene and ...

  3. INFLUENCE OF MACROMOLECULES ON CHEMICAL TRANSPORT

    EPA Science Inventory

    Macromolecules in the pore fluid influence the mobility of hydrophobic compounds through soils. his study evaluated the significance of macromolecules in facilitating chemical transport under laboratory conditions. Partition coefficients between 14C-labeled hexachlorobenzene and ...

  4. Acts of God, human influence and litigation

    NASA Astrophysics Data System (ADS)

    Marjanac, Sophie; Patton, Lindene; Thornton, James

    2017-09-01

    Developments in attribution science are improving our ability to detect human influence on extreme weather events. By implication, the legal duties of government, business and others to manage foreseeable harms are broadening, and may lead to more climate change litigation.

  5. Avenues of Influence: Cross-Cultural Implications

    DTIC Science & Technology

    2014-04-01

    will be helpful to future NSO collaborations for researchers to have a general understanding of the proposed research . 3.1. Data Collection...Human Research certification for herself and several research associates in her organization. 3.1.3. Proposed Procedure Three manipulations were...1: Proposed Behavioral Model 3.2. Social Influence Social influence is a burgeoning area of research , though one with a paucity of empirical

  6. Factors influencing job satisfaction and organizational commitment.

    PubMed

    Watson, Liana M

    2008-01-01

    To assess the relationship between intrinsic and extrinsic motivational factors influencing job satisfaction and the perspective of frontline medical imaging staff in acute care health care facilities in the United States. The sample consisted of 359 registered radiologic technologists who were working as staff technologists in acute care health care facilities in the United States. The results of the study suggest that satisfaction with intrinsic and extrinsic motivators influences overall satisfaction with the work environment and job and commitment to the employer.

  7. The Influence of law on Strategy

    DTIC Science & Technology

    2016-05-26

    Approved for public release; distribution is unlimited The Influence of Law on Strategy A Monograph by Kevin G. Rousseau School of Advanced...Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law , no person shall be subject...2016 4. TITLE AND SUBTITLE The Influence of Law on Strategy 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S

  8. Acid depositions and concrete attack: Main influences

    SciTech Connect

    Sersale, R.; Frigione, G.; Bonavita, L.

    1998-01-01

    The results of an experimental research on the factors responsible to a greater extent for the action of simulated acid precipitations on cement concrete works, both in static and in dynamic conditions, are discussed. The influence of the cement type, the role of calcium hydroxide, the influence of water-cement ratio, and the retard effect on assault, owing to a surface treatment with a water repellent agent, are emphasized.

  9. Career Satisfaction as a Factor Influencing Retention

    DTIC Science & Technology

    1976-05-14

    the influence of job satisfaction on first-term nt behavi ntent to reenlist as a criterion. Factors found to I related included not liking the work...benefits have been curtailed, largely due to the recent recession . When the economy brightens and civilian jobs become more plentiful, dissatisfactions...Satisfaction also his exchange power in the market place. Because economic value is influenced by consumer tastes and preferences, individual motivations

  10. Influence network in the Chinese stock market

    NASA Astrophysics Data System (ADS)

    Gao, Ya-Chun; Zeng, Yong; Cai, Shi-Min

    2015-03-01

    In a stock market, the price fluctuations are interactive, that is, one listed company can influence others. In this paper, we seek to study the influence relationships among listed companies by constructing a directed network on the basis of the Chinese stock market. This influence network shows distinct topological properties. In particular, a few large companies that can lead the tendency of the stock market are recognized. Furthermore, by analyzing the subnetworks of listed companies distributed in several significant economic sectors, it is found that the influence relationships are totally different from one economic sector to another, of which three types of connectivity as well as hub-like listed companies are identified. In addition, the rankings of listed companies obtained from the centrality metrics of the influence network are compared with those according to the assets, which gives inspiration to uncover and understand the importance of listed companies on the stock market. These empirical results are meaningful in providing these topological properties of the Chinese stock market and economic sectors as well as revealing the interactive influence relationships among listed companies.

  11. Neural mechanisms of social influence in adolescence

    PubMed Central

    Welborn, B. Locke; Lieberman, Matthew D.; Goldenberg, Diane; Fuligni, Andrew J.; Galván, Adriana

    2016-01-01

    During the transformative period of adolescence, social influence plays a prominent role in shaping young people’s emerging social identities, and can impact their propensity to engage in prosocial or risky behaviors. In this study, we examine the neural correlates of social influence from both parents and peers, two important sources of influence. Nineteen adolescents (age 16–18 years) completed a social influence task during a functional magnetic resonance imaging (fMRI) scan. Social influence from both sources evoked activity in brain regions implicated in mentalizing (medial prefrontal cortex, left temporoparietal junction, right temporoparietal junction), reward (ventromedial prefrontal cortex), and self-control (right ventrolateral prefrontal cortex). These results suggest that mental state reasoning, social reward and self-control processes may help adolescents to evaluate others’ perspectives and overcome the prepotent force of their own antecedent attitudes to shift their attitudes toward those of others. Findings suggest common neural networks involved in social influence from both parents and peers. PMID:26203050

  12. Neural mechanisms of social influence in adolescence.

    PubMed

    Welborn, B Locke; Lieberman, Matthew D; Goldenberg, Diane; Fuligni, Andrew J; Galván, Adriana; Telzer, Eva H

    2016-01-01

    During the transformative period of adolescence, social influence plays a prominent role in shaping young people's emerging social identities, and can impact their propensity to engage in prosocial or risky behaviors. In this study, we examine the neural correlates of social influence from both parents and peers, two important sources of influence. Nineteen adolescents (age 16-18 years) completed a social influence task during a functional magnetic resonance imaging (fMRI) scan. Social influence from both sources evoked activity in brain regions implicated in mentalizing (medial prefrontal cortex, left temporoparietal junction, right temporoparietal junction), reward (ventromedial prefrontal cortex), and self-control (right ventrolateral prefrontal cortex). These results suggest that mental state reasoning, social reward and self-control processes may help adolescents to evaluate others' perspectives and overcome the prepotent force of their own antecedent attitudes to shift their attitudes toward those of others. Findings suggest common neural networks involved in social influence from both parents and peers. © The Author (2015). Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.

  13. [Extraterrestrial influences on health and disease].

    PubMed

    Sitar, J

    1994-02-14

    As to extraterrestrial influences on man in health and disease so far only the effect of the sun and moon are known. This concerns the effect of solar radiation of different wavelengths and the effect of corpuscular solar radiation which has an impact on the condition of the terrestrial magnetic field and electric conditions in the atmosphere. Moreover there is also a question of important influences of gravitation (tides). Here the influence of the position of the moon in relation to the connecting line between sun and earth is involved. In the course of the synodic month (from new moon to the next new moon) a semilunar periodicity of different medical and geomagnetic indicators as well as meteorological ones plays a part. Based on his own research and that of others the author reaches the conclusion that extraterrestrial and terrestrial influences are interrelated and exert a mutual influence on each other and that it is not sensible to separate them strictly. Investigation of all the mentioned influences is important not only for biomedical prognosis but also for basic geophysical and meteorological research. Perspectively it would be useful to plan model experiments. The author feels it is his duty to refuse publication of different horoscopes in the mass media, whatever the intention. In the lay public this may lead to popularization of astrology which has nothing in common with serious research.

  14. Investigation of Social Influence Theory's Conception of Client Resistance.

    ERIC Educational Resources Information Center

    Ruppel, George; Kaul, Theodore J.

    1982-01-01

    Investigated the predictions of social influence theory with respect to client resistance to counselor influence. Data offered support for the social influence theory in that subjects' expectations of others' instrumental behavior were lower for those who viewed illegitimate counselors. (Author)

  15. Age-related differences in social influence on risk perception depend on the direction of influence.

    PubMed

    Knoll, Lisa J; Leung, Jovita T; Foulkes, Lucy; Blakemore, Sarah-Jayne

    2017-10-01

    Adolescents are particularly susceptible to social influence. Here, we investigated the effect of social influence on risk perception in 590 participants aged eight to fifty-nine-years tested in the United Kingdom. Participants rated the riskiness of everyday situations, were then informed about the rating of these situations from a (fictitious) social-influence group consisting of teenagers or adults, and then re-evaluated the situation. Our first aim was to attempt to replicate our previous finding that young adolescents are influenced more by teenagers than by adults. Second, we investigated the social-influence effect when the social-influence group's rating was more, or less, risky than the participants' own risk rating. Younger participants were more strongly influenced by teenagers than by adults, but only when teenagers rated a situation as more risky than did participants. This suggests that stereotypical characteristics of the social-influence group - risk-prone teenagers - interact with social influence on risk perception. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  16. Informational and Normative Influences in Conformity from a Neurocomputational Perspective.

    PubMed

    Toelch, Ulf; Dolan, Raymond J

    2015-10-01

    We consider two distinct influences that drive conformity behaviour. Whereas informational influences facilitate adaptive and accurate responses, normative influences bias decisions to enhance social acceptance. We explore these influences from a perspective of perceptual and value-based decision-making models and apply these models to classical works on conformity. We argue that an informational account predicts a surprising tendency to conform. Moreover, we detail how normative influences fit into this framework and interact with social influences. Finally, we explore potential neuronal substrates for informational and normative influences based on a consideration of the neurobiological literature, highlighting conceptual shortcomings particularly with regard to a failure to segregate informational and normative influences.

  17. Influence of musical groove on postural sway.

    PubMed

    Ross, Jessica M; Warlaumont, Anne S; Abney, Drew H; Rigoli, Lillian M; Balasubramaniam, Ramesh

    2016-03-01

    Timescales of postural fluctuation reflect underlying neuromuscular processes in balance control that are influenced by sensory information and the performance of concurrent cognitive and motor tasks. An open question is how postural fluctuations entrain to complex environmental rhythms, such as in music, which also vary on multiple timescales. Musical groove describes the property of music that encourages auditory-motor synchronization and is used to study voluntary motor entrainment to rhythmic sounds. The influence of groove on balance control mechanisms remains unexplored. We recorded fluctuations in center of pressure (CoP) of standing participants (N = 40) listening to low and high groove music and during quiet stance. We found an effect of musical groove on radial sway variability, with the least amount of variability in the high groove condition. In addition, we observed that groove influenced postural sway entrainment at various temporal scales. For example, with increasing levels of groove, we observed more entrainment to shorter, local timescale rhythmic musical occurrences. In contrast, we observed more entrainment to longer, global timescale features of the music, such as periodicity, with decreasing levels of groove. Finally, musical experience influenced the amount of postural variability and entrainment at local and global timescales. We conclude that groove in music and musical experience can influence the neural mechanisms that govern balance control, and discuss implications of our findings in terms of multiscale sensorimotor coupling. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

  18. Functional influences on orienting a reference frame.

    PubMed

    Carlson-Radvansky, L A; Tang, Z

    2000-07-01

    Spatial relational terms like above are defined with respect to a reference frame. Reference frames are imposed on reference objects and define the space in which to search for a located object. Reference frames have a number of parameters that must be set during spatial term assignment, including origin, scale, and orientation. Previous research has shown that a functional relationship between objects in the scene influences the selection of a reference frame (Carlson-Radvansky & Radvansky, 1996). However, because this work operated at the level of the reference frame, generalizing across various spatial terms, it is unclear how function had its influence. One possibility is that function influences how the parameters of a reference frame are set. Consistent with this idea, Carlson-Radvansky, Covey, and Lattanzi (1999) showed an influence of function on where the origin of a reference frame was imposed. The present paper demonstrates that function also influences how the orientation of the axes of a reference frame is set. The implications for setting multiple parameters of a reference frame are discussed.

  19. Sensorimotor influences on speech perception in infancy.

    PubMed

    Bruderer, Alison G; Danielson, D Kyle; Kandhadai, Padmapriya; Werker, Janet F

    2015-11-03

    The influence of speech production on speech perception is well established in adults. However, because adults have a long history of both perceiving and producing speech, the extent to which the perception-production linkage is due to experience is unknown. We addressed this issue by asking whether articulatory configurations can influence infants' speech perception performance. To eliminate influences from specific linguistic experience, we studied preverbal, 6-mo-old infants and tested the discrimination of a nonnative, and hence never-before-experienced, speech sound distinction. In three experimental studies, we used teething toys to control the position and movement of the tongue tip while the infants listened to the speech sounds. Using ultrasound imaging technology, we verified that the teething toys consistently and effectively constrained the movement and positioning of infants' tongues. With a looking-time procedure, we found that temporarily restraining infants' articulators impeded their discrimination of a nonnative consonant contrast but only when the relevant articulator was selectively restrained to prevent the movements associated with producing those sounds. Our results provide striking evidence that even before infants speak their first words and without specific listening experience, sensorimotor information from the articulators influences speech perception. These results transform theories of speech perception by suggesting that even at the initial stages of development, oral-motor movements influence speech sound discrimination. Moreover, an experimentally induced "impairment" in articulator movement can compromise speech perception performance, raising the question of whether long-term oral-motor impairments may impact perceptual development.

  20. Influence of interfaces on microbial activity.

    PubMed Central

    van Loosdrecht, M C; Lyklema, J; Norde, W; Zehnder, A J

    1990-01-01

    Bacterial adhesion in natural and artificial systems has been critically reviewed to investigate the influences exerted by the presence of interfaces. Numerous investigations have demonstrated that, in the presence of a solid phase, the activity of bacterial cultures is changed. Reviewing relevant literature, two problems were encountered. One is of an experimental nature. Due to lack of similarity in experimental conditions, disparate experiments often cannot be compared; their results may even appear conflicting. The other problem is of an interpretational nature: several hypothetical theories exist which try to explain the effect of surfaces on microbial activity. These theories often confuse changes in the medium and limitations in mass transfer which are due to the presence of solid surfaces (indirect influences) with changes in cell properties (direct influences). Whenever a surface is reported to influence the metabolism of bacteria, the action is found almost exclusively to be due to changes in the medium or environment and is therefore indirect. Based on data reported in the literature, and by using thermodynamic and kinetic considerations, it is concluded that so far neither experimental nor theoretical evidence exists for a direct influence of interfaces on microbial activity. PMID:2181260

  1. Impact of external influences on food packaging.

    PubMed

    Brody, A L

    1977-09-01

    Since the food supply is dependent upon an effective packaging system, threats to packaging represent implied threats to food processing and distribution. Enacted and potential legislation and regulation are retarding technological and commercial progress in food packaging and have already restricted some food packaging/processins systems. The results of these external influences is not simply the sum of the individual acts, but is a cascading self-imposed arresting of food packaging/processing advancement. The technological bases for the enacted and proposed legislation and regulation are presented in the enumeration of the external influences on food packaging. Economic and sociological arguments and facts surrounding the issues are also presented. Among the external influences on food packaging detailed are indirect additives, nutritional labeling, benefit:risk, solid waste and litter, environmental pollution, universal product code, and food industry productivity. The magnitude of the total impact of these external influences upon the food supply is so large that assertive action must be taken to channel these influences into more productive awareness. An objective and comprehensive public communications program supported by the technological community appears mandatory.

  2. Cenozoic climate change influences mammalian evolutionary dynamics

    PubMed Central

    Figueirido, Borja; Janis, Christine M.; Pérez-Claros, Juan A.; De Renzi, Miquel; Palmqvist, Paul

    2012-01-01

    Global climate change is having profound impacts on the natural world. However, climate influence on faunal dynamics at macroevolutionary scales remains poorly understood. In this paper we investigate the influence of climate over deep time on the diversity patterns of Cenozoic North American mammals. We use factor analysis to identify temporally correlated assemblages of taxa, or major evolutionary faunas that we can then study in relation to climatic change over the past 65 million years. These taxa can be grouped into six consecutive faunal associations that show some correspondence with the qualitative mammalian chronofaunas of previous workers. We also show that the diversity pattern of most of these chronofaunas can be correlated with the stacked deep-sea benthic foraminiferal oxygen isotope (δ18O) curve, which strongly suggests climatic forcing of faunal dynamics over a large macroevolutionary timescale. This study demonstrates the profound influence of climate on the diversity patterns of North American terrestrial mammals over the Cenozoic. PMID:22203974

  3. Influence of chemical elements on mammalian spermatozoa.

    PubMed

    Marzec-Wróblewska, U; Kamiński, P; Lakota, P

    2012-01-01

    Exposure to heavy metals is the most important risk factor in the assessment of spermatogenesis. About 30-40 % cases of infertility are caused by the male factor, and most of them are due to the small quantity of spermatozoa or to inferior spermatozoa quality. The negative impact on sperm motility, morphology and concentration of such chemical elements as Al, Cr, Cd, Pb or Fe was observed, while positive influence was noticed for Zn, Mg, and Ca. The influence of Mn, Cu, Ni or Se on spermatozoa is ambiguous. Chemical elements known as necessary for capacitation and acrosome reaction are Zn, Mg and Ca, while Cd and Pb disturb initiation and progress of the acrosome reaction. The positive effect of chemical elements Al, Cd, Cr, Cu, Ni, Pb, Se, and Zn, lies in their protection against oxidative stress. On the other hand, Al, Cu and Ni induce structural changes in the testes and epididymis or influence interactions with other chemical elements.

  4. Quantifying the effects of social influence

    PubMed Central

    Mavrodiev, Pavlin; Tessone, Claudio J.; Schweitzer, Frank

    2013-01-01

    How do humans respond to indirect social influence when making decisions? We analysed an experiment where subjects had to guess the answer to factual questions, having only aggregated information about the answers of others. While the response of humans to aggregated information is a widely observed phenomenon, it has not been investigated quantitatively, in a controlled setting. We found that the adjustment of individual guesses depends linearly on the distance to the mean of all guesses. This is a remarkable, and yet surprisingly simple regularity. It holds across all questions analysed, even though the correct answers differ by several orders of magnitude. Our finding supports the assumption that individual diversity does not affect the response to indirect social influence. We argue that the nature of the response crucially changes with the level of information aggregation. This insight contributes to the empirical foundation of models for collective decisions under social influence. PMID:23449043

  5. Cenozoic climate change influences mammalian evolutionary dynamics.

    PubMed

    Figueirido, Borja; Janis, Christine M; Pérez-Claros, Juan A; De Renzi, Miquel; Palmqvist, Paul

    2012-01-17

    Global climate change is having profound impacts on the natural world. However, climate influence on faunal dynamics at macroevolutionary scales remains poorly understood. In this paper we investigate the influence of climate over deep time on the diversity patterns of Cenozoic North American mammals. We use factor analysis to identify temporally correlated assemblages of taxa, or major evolutionary faunas that we can then study in relation to climatic change over the past 65 million years. These taxa can be grouped into six consecutive faunal associations that show some correspondence with the qualitative mammalian chronofaunas of previous workers. We also show that the diversity pattern of most of these chronofaunas can be correlated with the stacked deep-sea benthic foraminiferal oxygen isotope (δ(18)O) curve, which strongly suggests climatic forcing of faunal dynamics over a large macroevolutionary timescale. This study demonstrates the profound influence of climate on the diversity patterns of North American terrestrial mammals over the Cenozoic.

  6. Do hormones influence melanoma? Facts and controversies.

    PubMed

    Gupta, Amie; Driscoll, Marcia S

    2010-01-01

    The issue of whether hormones influence malignant melanoma (MM) has been controversial for many years. Although early case reports demonstrated a negative effect of hormones, recent evidence has not supported a potential role for hormones in MM. We address whether exogenous and endogenous hormones influence a woman's risk for MM or affect her prognosis if diagnosed with MM. Multiple epidemiologic studies show the use of oral contraceptives or hormone replacement therapy does not appear to increase a woman's risk for MM. Pregnancy does not appear to influence a woman's risk of MM, nor does pregnancy appear to affect prognosis in the woman diagnosed with MM. When counseling the woman who is diagnosed with MM during pregnancy or during the childbearing years, future use of oral contraceptives or hormone replacement therapy is not contraindicated; counseling concerning future pregnancies should be done on a case-by-case basis, with emphasis placed on established prognostic factors for MM.

  7. Using Network Dynamical Influence to Drive Consensus

    PubMed Central

    Punzo, Giuliano; Young, George F.; Macdonald, Malcolm; Leonard, Naomi E.

    2016-01-01

    Consensus and decision-making are often analysed in the context of networks, with many studies focusing attention on ranking the nodes of a network depending on their relative importance to information routing. Dynamical influence ranks the nodes with respect to their ability to influence the evolution of the associated network dynamical system. In this study it is shown that dynamical influence not only ranks the nodes, but also provides a naturally optimised distribution of effort to steer a network from one state to another. An example is provided where the “steering” refers to the physical change in velocity of self-propelled agents interacting through a network. Distinct from other works on this subject, this study looks at directed and hence more general graphs. The findings are presented with a theoretical angle, without targeting particular applications or networked systems; however, the framework and results offer parallels with biological flocks and swarms and opportunities for design of technological networks. PMID:27210291

  8. Influences that affect Maori women breastfeeding.

    PubMed

    Glover, Marewa; Manaena-Biddle, Harangi; Waldon, John

    2007-07-01

    This project aimed to identify the factors that influence Maori women's decision to breastfeed or not. During 2004-2005, a diverse demographic of Maori women and family members was selectively recruited from within a major urban area, small towns, and rural areas. Thirty women who had cared for a newborn within the previous three years were interviewed, alone or together with other family members. All participants self-identified as Maori and were over 16. Women who had artificially fed their babies were underrepresented. Most of the participants had breastfed and their determination to breastfeed was strong. This research proposes a new model for understanding how Maori women are diverted from breastfeeding. Five influences were identified: interruption to a breastfeeding culture; difficulty establishing breastfeeding within the first six weeks; poor or insufficient professional support; perception of inadequate milk supply; and returning to work. These influences occur in a temporal sequence and highlight opportunities for intervention. Factors that encourage breastfeeding are also discussed.

  9. Top consumer abundance influences lake methane efflux

    PubMed Central

    Devlin, Shawn P.; Saarenheimo, Jatta; Syväranta, Jari; Jones, Roger I.

    2015-01-01

    Lakes are important habitats for biogeochemical cycling of carbon. The organization and structure of aquatic communities influences the biogeochemical interactions between lakes and the atmosphere. Understanding how trophic structure regulates ecosystem functions and influences greenhouse gas efflux from lakes is critical to understanding global carbon cycling and climate change. With a whole-lake experiment in which a previously fishless lake was divided into two treatment basins where fish abundance was manipulated, we show how a trophic cascade from fish to microbes affects methane efflux to the atmosphere. Here, fish exert high grazing pressure and remove nearly all zooplankton. This reduction in zooplankton density increases the abundance of methanotrophic bacteria, which in turn reduce CH4 efflux rates by roughly 10 times. Given that globally there are millions of lakes emitting methane, an important greenhouse gas, our findings that aquatic trophic interactions significantly influence the biogeochemical cycle of methane has important implications. PMID:26531291

  10. Using Network Dynamical Influence to Drive Consensus

    NASA Astrophysics Data System (ADS)

    Punzo, Giuliano; Young, George F.; MacDonald, Malcolm; Leonard, Naomi E.

    2016-05-01

    Consensus and decision-making are often analysed in the context of networks, with many studies focusing attention on ranking the nodes of a network depending on their relative importance to information routing. Dynamical influence ranks the nodes with respect to their ability to influence the evolution of the associated network dynamical system. In this study it is shown that dynamical influence not only ranks the nodes, but also provides a naturally optimised distribution of effort to steer a network from one state to another. An example is provided where the “steering” refers to the physical change in velocity of self-propelled agents interacting through a network. Distinct from other works on this subject, this study looks at directed and hence more general graphs. The findings are presented with a theoretical angle, without targeting particular applications or networked systems; however, the framework and results offer parallels with biological flocks and swarms and opportunities for design of technological networks.

  11. Did the Great Recession influence retirement plans?

    PubMed

    Szinovacz, Maximiliane E; Davey, Adam; Martin, Lauren

    2015-04-01

    The recent recession constitutes one of the macro forces that may have influenced workers' retirement plans. We evaluate a multilevel model that addresses the influence of macro-, meso-, and micro-level factors on retirement plans, changes in these plans, and expected retirement age. Using data from Waves 8 and 9 of the Health and Retirement Study (N=2,618), we find that individuals with defined benefit plans are more prone to change toward plans to stop work before the stock market declined, whereas the opposite trend holds for those without pensions. Debts, ability to reduce work hours, and firm unionization also influenced retirement plans. Findings suggest retirement planning education may be particularly important for workers without defined pensions, especially in times of economic volatility.

  12. Influences of Microwave Irradiation on Environment

    NASA Astrophysics Data System (ADS)

    Murakami, H.; Abe, Y.; Iwata, T.; Kudo, I.; Saito, K.; Okuda, T.

    2004-12-01

    An experimental facility to evaluate the long-duration influence of microwave to environment, a so-called long duration microwave exposure facility (LDMEF), was constructed in Tsukuba in 1994, and so far irradiation tests on plants accumulated over 40,000 hours have been conducted with the aid of 2.45 GHz magnetron. The LDMEF consists of a pair of outdoor electromagnetically isolated areas, one under the influence of microwave irradiation with a 500 W magnetron and one without microwave irradiation. The growth rates of plants in both areas were compared and evaluated with the experimental data for the temperature distribution in the soil and power distribution of microwave. Although any appreciable influence of microwave was not noticed in the power density less than 10 mW/cm2 , the experimental results showed a significant growth rate enhancement when the power density became over 10 mW/cm2 . However, the growth was rather depressed when the power density increased over 15 mW/cm2 . These effects are well explained by the temperature and moisture in the soil which are also under an appreciable influence of microwave irradiation [1,2]. In this context, we newly constructed an indoor irradiation facility, in which the growth conditions of plants under a constant soil temperature can be maintained. In addition, irradiation with a 5.8 GHz magnetron will be conducted in the new facility. In parallel to a series of indoor and outdoor irradiation tests on plants, the influence of microwave irradiation on the growth pattern of albino mouse will be conducted. This experiment will be the first experimental evaluation for the influence of microwave irradiation on animals.

  13. Students' Dependence on Smart Phones: The Influence of Social Needs, Social Influences and Convenience

    ERIC Educational Resources Information Center

    Suki, Norazah Mohd

    2013-01-01

    Purpose: The purpose of this paper is to assess whether social needs, social influences and convenience of smart phones affects students' dependence on them. This research also examines whether students' dependence on smart phones influences their purchase behaviour. This investigation is conducted among the students in a public university in the…

  14. Students' Dependence on Smart Phones: The Influence of Social Needs, Social Influences and Convenience

    ERIC Educational Resources Information Center

    Suki, Norazah Mohd

    2013-01-01

    Purpose: The purpose of this paper is to assess whether social needs, social influences and convenience of smart phones affects students' dependence on them. This research also examines whether students' dependence on smart phones influences their purchase behaviour. This investigation is conducted among the students in a public university in the…

  15. Influence of skin diseases on fingerprint recognition.

    PubMed

    Drahansky, Martin; Dolezel, Michal; Urbanek, Jaroslav; Brezinova, Eva; Kim, Tai-hoon

    2012-01-01

    There are many people who suffer from some of the skin diseases. These diseases have a strong influence on the process of fingerprint recognition. People with fingerprint diseases are unable to use fingerprint scanners, which is discriminating for them, since they are not allowed to use their fingerprints for the authentication purposes. First in this paper the various diseases, which might influence functionality of the fingerprint-based systems, are introduced, mainly from the medical point of view. This overview is followed by some examples of diseased finger fingerprints, acquired both from dactyloscopic card and electronic sensors. At the end of this paper the proposed fingerprint image enhancement algorithm is described.

  16. Political and economic factors influencing contraceptive uptake.

    PubMed

    Sai, F T

    1993-01-01

    International, national and local level politics influence the uptake of contraception through consensuses, laws, financial and moral support or the creation of an enabling atmosphere. Opposition to contraception generally comes from some churches and groups opposed to particular technologies. Socio-economic factors, particularly education, the health care system and the perceived or actual cost of fertility regulation as compared to benefits expected from children also powerfully influence contraceptive use. For many poor women in developing countries their powerlessness in relation to their male partners is an important obstacle.

  17. Factors influencing households' participation in recycling.

    PubMed

    Vicente, Paula; Reis, Elizabeth

    2008-04-01

    The success of a recycling programme depends on the active and sustained participation of citizens in the correct separation and collection of recyclable waste. An effective study of strategies aimed at augmenting people's involvement in recycling involves understanding which factors influence the decision to co-operate with a recycling programme. This research investigates the influence of attitudes, incentives, presence of children in household and information through direct media, on households' participation in recycling. The results suggest that positive attitudes toward recycling and information are important factors in explaining recycling participation. Some guidelines that may be considered in future communication and intervention strategies designed to promote recycling participation are discussed.

  18. Influencing organisational culture: a leadership challenge.

    PubMed

    Muls, Ann; Dougherty, Lisa; Doyle, Natalie; Shaw, Clare; Soanes, Louise; Stevens, Anna-Marie

    In the wake of the Francis report, the need for NHS trusts and hospitals to adopt a culture of learning, safety and transparency has been highlighted. This article considers different aspects of culture in health care, and hones in on the link between culture and safety for patients in putting the patient first, embedding the 6Cs and considering the options to measure and influence organisational culture. The article reflects more deeply on how leadership across all levels can influence and inspire change in organisational culture, ensuring that the patient remains the focus of any changes in care delivery.

  19. Caffeine's Influence on Nicotine's Effects in Nonsmokers

    PubMed Central

    Blank, Melissa D.; Kleykamp, Bethea A.; Jennings, Janine M.; Eissenberg, Thomas

    2011-01-01

    Objective To determine if nicotine's effects are influenced by caffeine in nonsmoking, moderate-caffeine consuming individuals (N=20). Methods The first 3 sessions included one of 3 randomly ordered, double-blind caffeine doses (0, 75, or 150 mg, oral [po]) and 2 single-blind nicotine gum doses (2 and 4 mg) in ascending order. The fourth session (single blind) repeated the 0 mg caffeine condition. Results Nicotine increased heart rate and subjective ratings indicative of aversive effects, and decreased reaction times. These effects were independent of caffeine dose and reliable across sessions. Conclusions In nonsmokers, nicotine effects are not influenced by moderate caffeine doses. PMID:17555378

  20. Influencing factors in MMR immunisation decision making.

    PubMed

    Hill, Marie C; Cox, Carol L

    Immunisation decision making is not a straightforward process for parents. Many factors influence parental decision making on whether they immunise their child with the measles, mumps and rubella (MMR) vaccine. The feasibility study described in this article provides insight into influencing factors associated with decisions regarding the immunisation of children by parents. The study findings suggest that the practice nurse is a credible source of information for parents seeking informed decision making. At a time when the incidence of measles and mumps is rising in the UK, the provision of appropriate information by the practice nurse has the potential to increase uptake of the MMR vaccine.

  1. Financial planning. Influencing the decision makers.

    PubMed

    Isaac, E K

    1985-11-01

    Decision makers are most influenced by the impact on the whole, while budget preparers often concentrate on the upcoming fiscal year or on daily operations. This difference in approach becomes obvious in the budget process. Remember that your budget proposal is only one segment of the overall financial plan. Be aware of the goals of the governing body and of your CEO in projecting outcomes. Look to other disciplines to understand how they influence decision makers for funds. Resistance to this approach will neither enhance nor promote our competitive skills. We must think as financial planners to achieve our financial goals.

  2. Nerval influences on liver cytochrome P450.

    PubMed

    Klinger, W; Karge, E; Danz, M; Krug, M

    1995-09-01

    In male young adult Wistar rats the influences of nucleus raphe electrocoagulation, spinal cord dissection (cordotomy between C7 and Th1), vagotomy and denervation of liver hilus by phenol on liver cytochrome P450-system (cytochrome P450 concentration, ethylmorphine N-demethylation and ethoxycoumarin O-deethylation activities, hexobarbitone sleeping time) were investigated. In general the influences were small or negligible when compared with sham operated controls, only after vagotomy the depressing effect of sham operation was abolished. In all cases sham operation had a depressing effect until up to five weeks after operation.

  3. The influence of complexes on implicit learning.

    PubMed

    Shin, Yong-Wook; Lee, Joong-Sun; Han, Oh-Su; Rhi, Bou-Yong

    2005-04-01

    A century ago, Jung looked into the unconscious through complexes by using word association tests. Jung wrote, 'modern psychology with its investigation of complexes has opened up a psychic taboo area riddled with hopes and fears', and complexes remain an unexplored taboo area of research. In the present study, we have investigated the influence of complexes on unconscious cognitive processing, in particular on implicit learning. We have found that complexes shown to disturb conscious cognitive processing in fact enhanced the attention of the subjects and their performance on an implicit learning task. These results suggest that complexes are not just abstractions, but have various actual influences on both conscious and unconscious processing.

  4. Community influences on contraceptive use in Mozambique.

    PubMed

    Cau, Boaventura Manuel

    2015-01-01

    Fertility in sub-Saharan Africa remains the highest in the world. Yet, the average contraceptive prevalence in Africa is the lowest in major world regions and there is limited understanding of the mechanisms through which community context shapes contraceptive use in the region. Using data from the 2011 Mozambique Demographic and Health Survey, we examine the mechanisms through which community context influences women's use of modern methods of contraception in Mozambique. We find that community context influences the use of modern methods of contraception by shaping the environment in which women live. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. Detection of volcanic influence on global precipitation

    NASA Astrophysics Data System (ADS)

    Gillett, N. P.; Weaver, A. J.; Zwiers, F. W.; Wehner, M. F.

    2004-06-01

    Observations of terrestrial precipitation from the latter half of the 20th century are compared with precipitation simulated by the Parallel Climate Model to determine which external forcings have had a detectable influence on precipitation. Consistent with a previous study using another model, we found that the global mean response to all forcings combined was significantly correlated with that observed. A detection and attribution analysis applied to the simulated and observed precipitation indicated that the volcanic signal is detectable both on its own and in a multiple regression with other forcings. These results are consistent with the hypothesis that shortwave forcings exert a larger influence on precipitation than longwave forcings.

  6. Influence of Skin Diseases on Fingerprint Recognition

    PubMed Central

    Drahansky, Martin; Dolezel, Michal; Urbanek, Jaroslav; Brezinova, Eva; Kim, Tai-hoon

    2012-01-01

    There are many people who suffer from some of the skin diseases. These diseases have a strong influence on the process of fingerprint recognition. People with fingerprint diseases are unable to use fingerprint scanners, which is discriminating for them, since they are not allowed to use their fingerprints for the authentication purposes. First in this paper the various diseases, which might influence functionality of the fingerprint-based systems, are introduced, mainly from the medical point of view. This overview is followed by some examples of diseased finger fingerprints, acquired both from dactyloscopic card and electronic sensors. At the end of this paper the proposed fingerprint image enhancement algorithm is described. PMID:22654483

  7. The impact of social influence on adolescent intention to smoke: combining types and referents of influence.

    PubMed

    Vitória, Paulo D; Salgueiro, M Fátima; Silva, Sílvia A; De Vries, H

    2009-11-01

    Theory and research suggest that the intention to smoke is the main determinant of smoking initiation and emphasizes the role of cognitive and social factors on the prediction of the intention to smoke. However, extended models such as the I-Change and results from published studies reveal inconsistencies regarding the impact of social influence on the intention to smoke. Possible explanations for this may be the definition and measurement of the constructs that have been used. The current study was designed with two main goals: (i) to test a measurement model for social influence, combining different types of social influence (subjective norms, perceived behaviour, and direct pressure) with various referents of influence (parents, siblings, peers, and teachers); (ii) to investigate the impact of social influence on adolescent intention to smoke, controlling for smoking behaviour. LISREL was used to test these models. The sample includes 3,064 Portuguese adolescents, with a mean age of 13.5 years, at the beginning of the seventh school grade. The hypothesized measurement model of social influence was supported by results and explained 29% of the variance of the intention to smoke. A more extended model, including attitude and self-efficacy, explained 55% of the variance of the intention to smoke. Perceived behaviour of peers, parental norms, and perceived behaviour of parents were the social influence factors with impact on adolescent intention to smoke. Results suggest that different referents exert their influence through distinct types of social influence and recommend further work on the definition and measurement of social influence.

  8. A Review of Primary and Secondary Influences on Sport Expertise

    ERIC Educational Resources Information Center

    Baker, Joseph; Horton, Sean

    2004-01-01

    Sport scientists have examined numerous factors influencing the acquisition and manifestation of high levels of performance. These factors can be divided into variables having a primary influence on expertise and variables that have a secondary influence through their interaction with other variables. Primary influences on expertise include…

  9. Ion Exchange Membrane Influence on Ohmic Resistance

    USDA-ARS?s Scientific Manuscript database

    Selection of the proper ion exchange membrane can have a significant influence on bioelectrochemical system (BES) power densities. Because ions move across the membrane to achieve electroneutrality, the ion transport resistance (ohmic loss) needs to be minimized to increase power densities. Ohmic ...

  10. Factors Influencing Employee Learning in Small Businesses

    ERIC Educational Resources Information Center

    Coetzer, Alan; Perry, Martin

    2008-01-01

    Purpose: The purpose of this research is to identify key factors influencing employee learning from the perspective of owners/managers. Design/methodology/research: Data were gathered from owners/managers in a total of 27 small manufacturing and services firms through interviews and analysed using content analytic procedures. Findings: The…

  11. College Student Video Gaming and Parental Influence

    ERIC Educational Resources Information Center

    Chue, Maechi

    2011-01-01

    Video gaming is prevalent among college students, and researchers have documented negative consequences from some students' excessive video gaming, but the study of past and current parental influence on college student video gaming is limited. This study collected data from college students from several Midwestern U.S. universities using an…

  12. Motivational Influences on Response Inhibition Measures

    ERIC Educational Resources Information Center

    Leotti, Lauren A.; Wager, Tor D.

    2010-01-01

    Psychological research has placed great emphasis on inhibitory control due to its integral role in normal cognition and clinical disorders. The stop-signal task and associated measure--stop-signal reaction time (SSRT)--provides a well-established paradigm for measuring response inhibition. However, motivational influences on stop-signal…

  13. Social Influences on Interest. Presidential Address

    ERIC Educational Resources Information Center

    Bergin, David A.

    2016-01-01

    Where does enduring individual interest come from? One answer is, through social experience that derives from a need for belongingness. Because of this need, students seek social links that influence the development of individual interest. This may occur through experiences with parents, friends, passionate affinity groups, competition, public…

  14. Technology Adoption: Influence of Availability and Accessibility

    ERIC Educational Resources Information Center

    McConnell, William Stewart

    2009-01-01

    Farmers are small business leaders using available technology to remain competitive. The availability of technology is dependent on the suppliers' use of the marketing mix 4Ps theory--product, price, placement, and promotion. The purpose of this study was to determine how the relation between availability and accessibility influences the adoption…

  15. Investigation of radiation influence on LED

    NASA Astrophysics Data System (ADS)

    Rabinovich, O. I.; Legotin, S. A.; Didenko, S. I.; Krasnov, A. A.; Kovalev, A. N.; Podgornaya, S. V.

    2017-01-01

    In this paper the investigation goal was to study the radiation effect (irradiation by fast electrons) on detectors, LEDs electro-physical parameters as they are widely used in space shuttles, satellites and airplanes on which space radiation influence. It was detected the critical value of irradiation for the irreversible changes in LED. The way for reducing characteristics degradation is suggested.

  16. Factors influencing laser cutting of wood

    Treesearch

    V.G. Barnekov; C.W. McMillin; H.A. Huber

    1986-01-01

    Factors influencing the ability of lasers to cut wood may be generally classified into these three areas: 1) characteristics of the laser beam; 2) equipment and processing variables; and 3) properties of the workpiece. Effects of beam power, mode, polarization, and stability are discussed as are aspects of optics, location of focal point, feed speed, gas-jet assist...

  17. Social Influences in Sequential Decision Making

    PubMed Central

    Schöbel, Markus; Rieskamp, Jörg; Huber, Rafael

    2016-01-01

    People often make decisions in a social environment. The present work examines social influence on people’s decisions in a sequential decision-making situation. In the first experimental study, we implemented an information cascade paradigm, illustrating that people infer information from decisions of others and use this information to make their own decisions. We followed a cognitive modeling approach to elicit the weight people give to social as compared to private individual information. The proposed social influence model shows that participants overweight their own private information relative to social information, contrary to the normative Bayesian account. In our second study, we embedded the abstract decision problem of Study 1 in a medical decision-making problem. We examined whether in a medical situation people also take others’ authority into account in addition to the information that their decisions convey. The social influence model illustrates that people weight social information differentially according to the authority of other decision makers. The influence of authority was strongest when an authority's decision contrasted with private information. Both studies illustrate how the social environment provides sources of information that people integrate differently for their decisions. PMID:26784448

  18. Factors influencing woodlands of southwestern North Dakota

    Treesearch

    Michele M. Girard; Harold Goetz; Ardell J. Bjugstad

    1987-01-01

    Literature pertaining to woodlands of southwestern North Dakota is reviewed. Woodland species composition and distribution, and factors influencing woodland ecosystems such as climate, logging, fire, and grazing are described. Potential management and improvement techniques using vegetation and livestock manipulation have been suggested.

  19. Origin of Peer Influence in Social Networks

    NASA Astrophysics Data System (ADS)

    Pinheiro, Flávio L.; Santos, Marta D.; Santos, Francisco C.; Pacheco, Jorge M.

    2014-03-01

    Social networks pervade our everyday lives: we interact, influence, and are influenced by our friends and acquaintances. With the advent of the World Wide Web, large amounts of data on social networks have become available, allowing the quantitative analysis of the distribution of information on them, including behavioral traits and fads. Recent studies of correlations among members of a social network, who exhibit the same trait, have shown that individuals influence not only their direct contacts but also friends' friends, up to a network distance extending beyond their closest peers. Here, we show how such patterns of correlations between peers emerge in networked populations. We use standard models (yet reflecting intrinsically different mechanisms) of information spreading to argue that empirically observed patterns of correlation among peers emerge naturally from a wide range of dynamics, being essentially independent of the type of information, on how it spreads, and even on the class of underlying network that interconnects individuals. Finally, we show that the sparser and clustered the network, the more far reaching the influence of each individual will be.

  20. Sibling effects, environmental influences, and school dropout.

    PubMed

    Marjoribanks, Kevin

    2002-12-01

    Relations were examined between sibling variables, environmental influences, and the likelihood of dropping out of school. Data were collected from Australian adolescents (4,096 boys, 4,570 girls). Findings indicated that, after taking into account measures of distal contexts and proximal learning settings, sibling variables continued to have small but significant associations with adolescents' school dropout behavior.

  1. Culture Influences on English Language Teaching

    ERIC Educational Resources Information Center

    Zhang, Xue-wei; Yan, Ying-jun

    2006-01-01

    It's obvious that the teaching situation and teaching methods used in English Language Teaching (ELT) in China need to be changed to involve culture instead of language knowledge only. To further explain the importance of culture teaching, teachers need to know to what extent cultural background knowledge influences language learning and teaching,…

  2. Technology Adoption: Influence of Availability and Accessibility

    ERIC Educational Resources Information Center

    McConnell, William Stewart

    2009-01-01

    Farmers are small business leaders using available technology to remain competitive. The availability of technology is dependent on the suppliers' use of the marketing mix 4Ps theory--product, price, placement, and promotion. The purpose of this study was to determine how the relation between availability and accessibility influences the adoption…

  3. Crown ratio influences allometric scaling in trees

    Treesearch

    Annikki Makela; Harry T. Valentine

    2006-01-01

    Allometric theories suggest that the size and shape of organisms follow universal rules, with a tendency toward quarter-power scaling. In woody plants, however, structure is influenced by branch death and shedding, which leads to decreasing crown ratios, accumulation of heartwood, and stem and branch tapering. This paper examines the impacts on allometric scaling of...

  4. Hydrologic processes influencing meadow ecosystems [chapter 4

    Treesearch

    Mark L. Lord; David G. Jewett; Jerry R. Miller; Dru Germanoski; Jeanne C. Chambers

    2011-01-01

    The hydrologic regime exerts primary control on riparian meadow complexes and is strongly influenced by past and present geomorphic processes; biotic processes; and, in some cases, anthropogenic activities. Thus, it is essential to understand not only the hydrologic processes that operate within meadow complexes but also the interactions of meadow hydrology with other...

  5. Understanding Peer Influence in Children and Adolescents

    ERIC Educational Resources Information Center

    Prinstein, Mitchell J., Ed.; Dodge, Kenneth A., Ed.

    2008-01-01

    Scientists, educators, and parents of teens have long recognized the potency of peer influences on children and youth, but until recently, questions of how and why adolescents emulate their peers were largely overlooked. This book presents a framework for understanding the processes by which peers shape each other's attitudes and behavior, and…

  6. Influence of the Internet on Studying English

    ERIC Educational Resources Information Center

    Molchanova, Irma Igorevna

    2015-01-01

    The article considers theoretical aspects of influence of the Internet on studying English, including on the opportunities of listening and increase of motivation for studying English. The characteristic of blended learning technology in studying the foreign languages is given. The practical justification of the efficiency of studying English…

  7. Career Influences of Music Education Audition Candidates

    ERIC Educational Resources Information Center

    Rickels, David A.; Brewer, Wesley D.; Councill, Kimberly H.; Fredrickson, William E.; Hairston, Michelle; Perry, David L.; Porter, Ann M.; Schmidt, Margaret

    2013-01-01

    In this descriptive study, we examined the influences and experiences motivating students to enter college-level music schools as reported by a population of precollegiate students auditioning (but not yet accepted) to music education degree programs. As a follow-up to a published pilot study, this research was designed to quantify the various…

  8. Mathematical Competence: Personal and Social Influences.

    ERIC Educational Resources Information Center

    Randhawa, Bikkar S.; And Others

    In mathematics, Canadian students perform poorly, and enrollment in Canadian postsecondary institutions is low, particularly for women. Clearly, there is a need to understand the personal and social factors that influence mathematics achievement and academic choices. A. Bandura's self-efficacy theory (1977, 1982) implies that academic choices are…

  9. Influence of Television Commercials on Young Children.

    ERIC Educational Resources Information Center

    Lam, Pamela Y. Y.

    This study investigated the influence of television commercials for toys and cereals on young children. Forty-four children, ranging in age from 4 to 7 years, were interviewed regarding their television viewing habits, their attitudes toward television commercials, their demands for their mothers to buy cereals and toys, and their interpretation…

  10. Social Influences on Interest. Presidential Address

    ERIC Educational Resources Information Center

    Bergin, David A.

    2016-01-01

    Where does enduring individual interest come from? One answer is, through social experience that derives from a need for belongingness. Because of this need, students seek social links that influence the development of individual interest. This may occur through experiences with parents, friends, passionate affinity groups, competition, public…

  11. Exploring Influences on Later Life Learning

    ERIC Educational Resources Information Center

    Withnall, Alexandra

    2006-01-01

    Academic debate about education and ageing issues has hitherto been based largely on provider and practitioner concerns. Here, the first stage of a two-year research project that aimed to move the focus to older learners themselves is discussed. The aim in this initial stage was to construct a conceptual model of life course influences on older…

  12. Influencing Motivation in the Foreign Language Classroom

    ERIC Educational Resources Information Center

    Nicholson, Simon James

    2013-01-01

    Motivation is one of the main determining factors of success in developing a second or foreign language. However, motivation is a complex phenomenon and the more its constructs are understood the better we are able to understand the extent to which we can influence it. Teachers can cultivate student motivation to varying degrees and play a central…

  13. Influence Function Learning in Information Diffusion Networks

    PubMed Central

    Du, Nan; Liang, Yingyu; Balcan, Maria-Florina; Song, Le

    2015-01-01

    Can we learn the influence of a set of people in a social network from cascades of information diffusion? This question is often addressed by a two-stage approach: first learn a diffusion model, and then calculate the influence based on the learned model. Thus, the success of this approach relies heavily on the correctness of the diffusion model which is hard to verify for real world data. In this paper, we exploit the insight that the influence functions in many diffusion models are coverage functions, and propose a novel parameterization of such functions using a convex combination of random basis functions. Moreover, we propose an efficient maximum likelihood based algorithm to learn such functions directly from cascade data, and hence bypass the need to specify a particular diffusion model in advance. We provide both theoretical and empirical analysis for our approach, showing that the proposed approach can provably learn the influence function with low sample complexity, be robust to the unknown diffusion models, and significantly outperform existing approaches in both synthetic and real world data. PMID:25973445

  14. SOCIO-CULTURAL INFLUENCES AND LEARNING CHANNELS.

    ERIC Educational Resources Information Center

    DEUTSCH, CYNTHIA P.

    THE HYPOTHESIS THAT ENVIRONMENTAL CIRCUMSTANCES INFLUENCE THE PROCESS OF KNOWLEDGE ACQUISITION IS DISCUSSED. THE ROLE OF PARTIAL AND FULL SENSORY ISOLATION AND DEPRIVATION AND ITS NEGATIVE EFFECT ON LEARNING IS SHOWN TO BE SUPPORTED BY RESEARCH. THE INSTITUTE FOR DEVELOPMENTAL STUDIES AT NEW YORK UNIVERSITY IS ENGAGED IN RESEARCH DEALING WITH THE…

  15. Influencing Motivation in the Foreign Language Classroom

    ERIC Educational Resources Information Center

    Nicholson, Simon James

    2013-01-01

    Motivation is one of the main determining factors of success in developing a second or foreign language. However, motivation is a complex phenomenon and the more its constructs are understood the better we are able to understand the extent to which we can influence it. Teachers can cultivate student motivation to varying degrees and play a central…

  16. Experimental Influence Coefficients and Vibration Modes

    NASA Technical Reports Server (NTRS)

    Weidman, Deene J.; Kordes, Eldon E.

    1959-01-01

    Test results are presented for both symmetrical and antisymmetrical static loading of a wing model mounted on a three-point support system. The first six free-free vibration modes were determined experimentally. A comparison is made of the symmetrical nodal patterns and frequencies with the symmetrical nodal patterns and frequencies calculated from the experimental influence coefficients.

  17. Factors Influencing Employee Learning in Small Businesses

    ERIC Educational Resources Information Center

    Coetzer, Alan; Perry, Martin

    2008-01-01

    Purpose: The purpose of this research is to identify key factors influencing employee learning from the perspective of owners/managers. Design/methodology/research: Data were gathered from owners/managers in a total of 27 small manufacturing and services firms through interviews and analysed using content analytic procedures. Findings: The…

  18. Successful Aging: Early Influences and Contemporary Characteristics

    ERIC Educational Resources Information Center

    Pruchno, Rachel A.; Wilson-Genderson, Maureen; Rose, Miriam; Cartwright, Francine

    2010-01-01

    Purpose: Positing that successful aging has independent, yet related, dimensions that are both objective and subjective, we examine how early influences and contemporary characteristics define 4 groups of people. Design and Methods: Data were gathered from 5,688 persons aged 50-74 years living in New Jersey who participated in telephone…

  19. How Boards and Presidents Influence Credit Ratings

    ERIC Educational Resources Information Center

    Kedem, Karen

    2011-01-01

    Moody's Investors Service provides credit ratings for hundreds of private and public colleges and universities--ratings that can strongly influence the interest rates higher-education institutions can obtain when they want to borrow money. How colleges are governed and managed are key determinants of those credit ratings, especially in an…

  20. School Influences on Child and Youth Development

    ERIC Educational Resources Information Center

    Osher, David; Kendziora, Kimberly; Spier, Elizabeth; Garibaldi, Mark L.

    2014-01-01

    Schools play a key role in child and youth development as both social microcosms of the broader society and reciprocally influencing people and communities. As such, schools can function as a protective factor that promotes safety, motivation, relationships, and support for positive student outcomes. However, schools may also function as a risk…