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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. PMID:26975005

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

    PubMed

    Lee, Byong-Gweon; Lee, Jung-Suk; Luoma, Samuel N

    2006-07-01

    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 degrees 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. PMID:16833157

  5. 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.

  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 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

  9. Bioavailability and oxidative stress of cadmium to Corbicula fluminea.

    PubMed

    Ren, Jinghua; Luo, Jun; Ma, Hongrui; Wang, Xiaorong; Ma, Lena Q

    2013-04-01

    This work set out to study the effects of cadmium (Cd) in sediments on the antioxidant enzyme activities in the digestive gland of Asian clam Corbicula fluminea and to explore the potential for applying these responses to evaluate the Cd-contaminated sediment. Additionally, diffusive gradients in thin-films (DGT) technique was used to predict the response of its antioxidant defense system. The sediments, collected from Taihu Lake, were spiked with Cd at different concentrations (0.72, 0.91, 1.62, 2.59, 11.2, 20.4 and 40.6 mg kg(-1), dry weight). Asian clam was cultivated for 28 days. Concentrations of Cd in the body of Asian clam had a good relationship with concentrations of Cd in overlying water and sediments, as measured by DGT. Cd affected these biochemical parameters significantly, especially for superoxide (SOD), peroxidase (POD) and glutathione (GSH), which began to show higher sensitivity and have a significant difference in low dosage (0.91 mg Cd kg(-1)) compared with blank. Contents of MDA and MT, which were induced by Cd, increased with the increasing Cd concentration in sediments and reached peak values at 11.2 and 20.4 mg kg(-1), respectively, after 28 days exposure. All of these results suggested that biochemical responses cooperated in detoxifying and maintaining cellular metabolic homeostasis. The R(2) of regression analysis between the contents of MT and the concentrations of Cd measured by DGT, in sediments and soft body were 0.71, 0.94 and 0.88 after 28 days exposure. This suggested that DGT measurement could predict the response of MT. Cd accumulation, GSH and MT were indispensable biomarkers and the MDA content and DGT appeared to be promising biomarkers. The results clearly indicated that Cd could induce oxidative stress in the digestive gland of Asian clam. The combination of biomonitors with DGT can obtain different information about Cd bioavailability and confirm the significance of applying a suite of biomarkers rather than a selective

  10. In Vitro Interactions of Asian Freshwater Clam (Corbicula fluminea) Hemocytes and Cryptosporidium parvum Oocysts

    PubMed Central

    Graczyk, T. K.; Fayer, R.; Cranfield, M. R.; Conn, D. B.

    1997-01-01

    Corbicula fluminea hemocytes phagocytosed infectious oocysts of Cryptosporidium parvum in vitro. After 15, 30, 60, 90, and 120 min of incubation, averages of 35.8, 58.0, 69.7, 77.7, and 81.6% of the oocysts were phagocytosed by 24.3, 70.0, 78.5, 87.3, and 93.0% of the hemocytes, respectively. A single clam can retain by phagocytosis an average of 1.84 x 10(sup6) oocysts per ml of hemolymph. C. fluminea bivalves can serve as biological indicators of contamination of wastewaters and agricultural drainages with Cryptosporidium. PMID:16535656

  11. Effects of the invasive clam Corbicula fluminea (Müller, 1774) on an estuarine microbial community.

    PubMed

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

    2016-10-01

    The Asian clam Corbicula fluminea (Müller, 1774) is well recognized for its invasive behavior and high ecological and economic impacts, being classified as one of the 100 worst invasive alien species (IAS) in Europe. In this study, we performed a manipulative experiment under natural conditions to assess the effects of C. fluminea on sediments biochemistry and on the structure of an estuarine microbial (fungi and bacteria) community. We placed 5 treatments (control, rock, closed, live and open) for 2months in the Minho estuary (NW Iberian Peninsula). No differences were detected between treatments regarding the values of carbon (C), nitrite (NO2(-)), ammonium (NH4(+)), phosphate (PO4(3-)) and calcium (Ca) in the sediments; however, potassium (K) had higher values in the open treatment. Furthermore, we found that the presence of live C. fluminea stimulated fungal biomass (but not diversity) and bacterial diversity. Bioturbation activities by C. fluminea are possibly the main mechanism explaining these results; however, other factors such as the presence of other macroinvertebrate species and/or production of feces and pseudofeces by C. fluminea cannot be excluded. To our knowledge, this is the first manipulative experiment under natural conditions that clearly shows the effects of C. fluminea on an estuarine microbial community. Given the widespread distribution of this IAS and the paucity of quantitative assessments of invasive bivalves' effects on microbial communities, it will be important that future studies further investigate these processes. PMID:27265734

  12. Online detection of waterborne bioavailable copper by valve daily rhythms in freshwater clam Corbicula fluminea.

    PubMed

    Jou, L J; Chen, W Y; Liao, C M

    2009-08-01

    Freshwater clam Corbicula fluminea, a surrogate species in metal toxicity testing, is a promising bioindicator of impairment in aquatic ecosystems. Little is known, however, about the relationship between clam valve daily rhythmic response and metal bioavailability related to a metal biological early warning system (BEWS) design. The purpose of this study was to link biotic ligand model (BLM)-based bioavailability and valve daily rhythm in C. fluminea to design a biomonitoring system for online in situ detection of waterborne copper (Cu). We integrated the Hill-based dose-time-response function and the fitted daily rhythm function of valve closure into a constructed programmatic mechanism. The functional presentation of the present dynamic system was completely demonstrated by employing a LabVIEW graphic control program in a personal computer. We used site-specific effect concentration causing 10% of total valve closure response (EC10) as the detection threshold to implement the proposed C. fluminea-based Cu BEWS. Here our results show that the proposed C. fluminea-based BEWS could be deliberately synthesized to online in situ transmit rapidly the information on waterborne bioavailable Cu levels under various aquatic environmental conditions through monitoring the valve daily rhythmic changes. We suggested that the developed C. fluminea-based dynamic biomonitoring system could assist in developing technically defensible site-specific water quality criteria to promote more efficient uses in water resources for protection of species health in aquatic environments. PMID:18607762

  13. 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.

  14. The impact of paracetamol on selected biomarkers of the mollusc species Corbicula fluminea.

    PubMed

    Brandão, Fátima Pinto; Pereira, Joana Luísa; Gonçalves, Fernando; Nunes, Bruno

    2014-01-01

    The Asian clam Corbicula fluminea is an invasive bivalve that has recently spread in Europe and currently represents a large portion of the aquatic biomass in specific areas. Because of the impacts that the species may have in invaded ecosystems, increased knowledge on the physiologic features of the species life-cycle under different environmental scenarios (e.g., contamination events) is critical to understand the dynamics of the invasion and resulting ecosystem imbalance. The presence of pharmaceutical residues in the aquatic environment has recently received great attention since high levels of contamination have been found, not only in sewage treatment plant effluents, but also in open waters. The present article reports toxicological biochemical effects of paracetamol to Corbicula fluminea following short- and long-term exposures. Oxidative stress parameters were specially focused namely catalase (CAT), glutathione S-transferases (GSTs), and glutathione reductase (GRed). The effect of tested substances on lipid peroxidation was also investigated. Paracetamol did not induce alterations on CAT activity, caused a significant decrease of GSTs activity following short- and long-term exposure (LOEC values of 532.78 mg L(-1) and 30.98 μg L(-1) , respectively), and was responsible for a significant and dose-dependent decrease of GRed activity in short- and long-term exposures. These results indicate that exposure to paracetamol can provoke significant alterations on the cellular redox status of C. fluminea. PMID:21956867

  15. 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.

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

    USGS Publications Warehouse

    French, John R. P., III; 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.

  17. 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...

  18. Detection and analysis of the microdistribution of uranium in the gills of freshwater Corbicula fluminea by SIMS technique

    NASA Astrophysics Data System (ADS)

    Tessier, C.; Suhard, D.; Simon, O.; Floriani, M.; Rebière, F.; Jourdain, J.-R.

    2009-06-01

    The microdistribution of uranium in the gills of freshwater bivalve Corbicula fluminea following chronic direct exposure to this radioelement has been investigated using the SIMS technique. Different exposure levels and exposure durations have been studied. The SIMS mass spectra and 238U + ion images produced with a SIMS CAMECA 4F-E7 show an U accumulation with the lower aqueous U concentration (20 μg/L) and the influence of the exposure levels on the bioaccumulation capacities. Furthermore, the ionic images display a heterogeneous distribution of uranium within the gill structure whatever the exposure conditions are. This study, in keeping with the ENVIRHOM French research program, was led to the conclusion that ion microscopy is an appropriate analytical method for trace elements and can give elemental cartography in a biological tissue section.

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

    PubMed

    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

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

    PubMed

    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. PMID:20567799

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

    USGS Publications Warehouse

    French, John R. P., III; 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.

  4. 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. PMID:23771443

  5. [Effects of Corbicula fluminea bioturbation on the community composition and abundance of ammonia-oxidizing archaea and bacteria in surface sediments].

    PubMed

    Wang, Xue; Zhao, Da-Yong; Zeng, Jin; Yu, Duo-Wei; Wu, Qing-Long

    2014-06-01

    To better understand the effects of Corbicula fluminea bioturbation on the ammonia-oxidizing microorganisms in the surface sediment, sediment-water microcosms with different densities of Corbicula fluminea were constructed. Clone libraries and real-time qPCR were applied to analyze the community composition and abundance of ammonia-oxidizing archaea (AOA) and bacteria (AOB) in the surface sediments. The results obtained indicated that the bioturbation of Corbicula fluminea accelerated the release of nitrogen from the surface sediment. In the amoA gene clone libraries, the identified AOA amoA gene sequences affiliated with the two known clusters (marine and soil clusters). The identified AOB amoA gene sequences mostly belonged to the Nitrosomonas of beta-Proteobacteria. The abundance of the bacterial amoA gene was higher than that of the archaeal amoA gene in all treatments. With increasing density of Corbicula fluminea, decreased abundances of the bacterial amoA gene were observed. At the same time, the diversity of AOA and AOB reduced in the Corbicula fluminea containing microcosms. In conclusion, the bioturbation of Corbicula fluminea could affected the community composition and abundance of ammonia-oxidizing microorganisms in surface sediments. PMID:25158512

  6. 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).

  7. 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. PMID:27090524

  8. 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

  9. Sodium sulfate impacts feeding, specific dynamic action, and growth rate in the freshwater bivalve Corbicula fluminea.

    PubMed

    Soucek, David John

    2007-08-01

    Sodium sulfate is a ubiquitous salt that reaches toxic concentrations due to mining and other industrial activities, yet is currently unregulated at the Federal level in the United States. Previous studies have documented reduced growth of clams downstream of sulfate-dominated effluents, altered bioenergetics in filter-feeding invertebrates, and interactions between sulfate and other toxicants. Therefore, the purpose of this study was to determine if sodium sulfate affects the bioenergetics of the filter-feeding, freshwater bivalve, Corbicula fluminea, and the mechanism by which the effects are elicited. In addition to measuring effects on feeding, respiration and growth rates, I evaluated the relative sensitivity of a green algae consumed by clams to determine if top-down or bottom-up effects might be exhibited under field conditions. This study demonstrated that sodium sulfate had no effect on basal metabolic rates, but significantly reduced the feeding, post-feeding metabolic, and growth rates of C. fluminea. The proposed mechanism for these impacts is that filtering rates are reduced upon exposure, resulting in reduced food consumption and therefore, preventing increased metabolic rates normally associated with post-feeding specific dynamic action (SDA). In the field, these effects may cause changes in whole stream respiration rates and organic matter dynamics, as well as alter uptake rates of other food-associated contaminants like selenium, the toxicity of which is known to be antagonized by sulfate, in filter-feeding bivalves. PMID:17590452

  10. Abortive second meiosis detected in cytochalasin-treated eggs in androgenetic diploid Corbicula fluminea.

    PubMed

    Ishibashi, Ryo; Komaru, Akira

    2006-05-01

    The hermaphroditic diploid clam Corbicula fluminea reproduces by androgenesis. In the control (androgenetic development), all maternal chromosomes and maternal centrosomes at the meiotic poles were extruded as two first polar bodies and subsequently second meiosis did not occur. In eggs treated with cytochalasin D (CD) to inhibit the polar body extrusion, the second meiosis was abortive. After the first meiosis, two centrosomes at the spindle poles remained in the cytoplasm because of the effect of CD. The chromosomes divided into two groups at anaphase-I as observed in the control eggs. Two centrosomes divided into four just after the first meiosis but did not separate completely. The microtubules from the centrosomes were rather short. So at the second meiosis, two monoasters or tetrapolar spindles were formed. The fluorescence signal from microtubules of the monoaster or tetrapolar spindle was weak compared with the spindle at the first meiosis. The maternal chromosomes on the monoaster or tetrapolar spindle did not move, and became large female pronuclei. The pronuclei became the metaphase chromosomes on the spindle for the first cleavage. The present study suggests that second meiosis regulating factors may be abortive in androgenetic diploid C. fluminea. PMID:16681653

  11. A dynamic artificial clam (Corbicula fluminea) allows parsimony on-line measurement of waterborne metals.

    PubMed

    Jou, Li-John; Liao, Chung-Min

    2006-11-01

    We introduce a novel on-line biomonitoring system based on a valvometric conversion technique for clam Corbicula fluminea, allowing for rapid, continuous, and ecological relevant water quality control. Our model builds upon the basic principles of biological early warning system model in two ways. We first adopted a risk-based methodology to build a dynamic artificial clam for simulating how the bivalve closure rhythm in response to waterborne copper (Cu) and cadmium (Cd). Secondly, we integrated a probabilistic model associated with the time-varying dose-response relationships of valve closing behavior into the mechanisms of a dynamic artificial clam, allowing estimation of the time-varying waterborne Cu/Cd concentrations for on-line providing the outcomes of the toxicity detection technique. Measurements with Cu/Cd were performed and the calculated EC50 values were compared with published data for the valve movement test with C. fluminea. This proposed dynamic artificial clam provides a better quantitative understanding of on-line biomonitoring measurements of waterborne metals and may foster applications in clam farm management strategy and ecotoxicological risk assessment. PMID:16515830

  12. Proteomic changes in Corbicula fluminea exposed to wastewater from a psychiatric hospital.

    PubMed

    Bebianno, M J; Sroda, S; Gomes, T; Chan, P; Bonnafe, E; Budzinski, H; Geret, F

    2016-03-01

    The increase use of pharmaceutical compounds in veterinary practice and human population results in the ubiquitous presence of these compounds in aquatic ecosystems. Because pharmaceuticals are highly bioactive, there is concern about their toxicological effects in aquatic organisms. Therefore, the aim of this study was to assess the effects of an effluent from a psychiatric hospital (containing a complex mixture of 25 pharmaceutical compounds from eleven therapeutic classes) on the freshwater clam Corbicula fluminea using a proteomic approach. The exposure of C. fluminea to this complex effluent containing anxiolytics, analgesics, lipid regulators, beta blockers, antidepressants, antiepileptics, antihistamines, antihypertensives, antiplatelets and antiarrhythmics induced protein changes after 1 day of exposure in clam gills and digestive gland more evident in the digestive gland. These changes included increase in the abundance of proteins associated with structural (actin and tubulin), cellular functions (calreticulin, proliferating cell nuclear antigen (PCNA), T complex protein 1 (TCP1)) and metabolism (aldehyde dehydrogenase (ALDH), alcohol dehydrogenase, 6 phosphogluconate dehydrogenase). Results from this study indicate that calreticulin, PCNA, ALDH and alcohol dehydrogenase in the digestive gland and T complex protein 1 (TCP1)) and 6 phosphogluconate dehydrogenase in the gills represent useful biomarkers for the ecotoxicological characterization of psychiatric hospital effluents in this species. PMID:26423280

  13. 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.

  14. Biomarkers in the freshwater bivalve Corbicula fluminea confined downstream a domestic landfill leachate discharge.

    PubMed

    de Oliveira, Luciana Fernandes; Santos, Caroline; Dos Reis Martinez, Claudia Bueno

    2016-07-01

    Landfills represent a severe environmental problem mainly due to the generation of leachates, and this study aimed to evaluate sublethal effects of a domestic landfill leachate in the freshwater bivalve Corbicula fluminea. Clams were submitted to in situ tests along a stream, at three sites, representing increasing distances from the leachate discharge (Pq1, Pq2, and Pq3), for 1, 5, and 15 days. The following biomarkers were analyzed in the gills and digestive glands: 7-ethoxyresorufin-O-deethylase (EROD) and glutathione S-transferase (GST) activities, multixenobiotic resistance mechanism (MXR), total antioxidant capacity (TAC), reactive oxygen species (ROS), and lipid peroxidation (LPO). Metallothionein (MT) content was determined in the gills and DNA damage in hemocytes. The mortality rate of animals during in situ tests was reduced as the distance from the leachate discharge source increased. On the other hand, biomarker results showed sublethal effects on C. fluminea confined at all sites of PqS. GST, TAC, ROS, and DNA damage were the most significant biomarkers for this species and should be considered for future monitoring and assessment of freshwater environments located in landfill areas. PMID:27040540

  15. 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. PMID:27097092

  16. Accumulation and risk assessment of heavy metals in sediments and zoobenthos (Bellamya aeruginosa and Corbicula fluminea) from Lake Taihu.

    PubMed

    Kong, Ming; Hang, Xiaoshuai; Wang, Longmian; Yin, Hongbin; Zhang, Yimin

    2016-01-01

    Accumulation and risk assessment of metals in sediments and zoobenthos (Bellamya aeruginosa and Corbicula fluminea) from Lake Taihu were studied. Results showed that metal (Cr, Cd, Cu, Zn, Pb and Ni) concentrations in Lake Taihu varied greatly, and Cd in the Zhushan Bay showed higher bioavailability compared to the other metals studied. The spatial distribution of metals in B. aeruginosa and C. fluminea was similar to that in sediments. Zn and Cu exhibited the higher mean concentration in B. aeruginosa and C. fluminea, which was in good accordance with its higher content in surrounding sediment. Labile fractions (i.e., acid-soluble (F1), reducible (F2) and F1+F2) of Cu and Zn in sediments showed a significant positive correlation with them in B. aeruginosa (P<0.01); no correlation relationship was found for metals (Cd, Cr, Cu, Zn, Pb and Ni) between in the tissue of C. fluminea and in sediments. The results of ecological risk assessment showed that Zhushan Bay was seriously contaminated by metal Cd, as it made the main contribution of all the metals. Total target hazard quotients indicated that adults and children both had potential health risk through consuming C. fluminea. Hazard index values suggested that adults and children might experience adverse health effects through consuming B. aeruginosa and C. fluminea. PMID:26744952

  17. 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.

  18. 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. PMID:22476670

  19. Experimental research on the impact of Corbicula fluminea on DIN exchange at a tidal flat sediment-water interface

    NASA Astrophysics Data System (ADS)

    Liu, Jie; Chen, Zhenlou; Xu, Shiyuan; Zheng, Xiangmin

    2007-10-01

    Based on a simulative experiment and a comparison analysis, the effect of bivalve Corbicula fluminea activity on sediment-water exchange of dissolved inorganic nitrogen (DIN) is studied. The areas included three intertidal flat sites of the Changjiang (Yangtze) River estuary in China. The interface exchange flux of ammonium, nitrate and nitrite in the short experiment (6 h) was -46.4-40, -74.8-929.1 and 2.5-14.6 µmol/(m2·h), respectively. It was found that the burrowing activities of C. fluminea increased NH{4/+} and NO{3/-} release from sediments to overlying water in the short-term experiment. During long-term incubation, NH{4/+} and NO{3/-} released in turn from the sediments. At the beginning of incubation, bioturbation by C. fluminea could accelerate NH{4/+} release from sediments 2-17 times in different sites, resulting in stronger nitrification and increased NO{3/-} concentrations in the overlying water. Sediment profile analysis post-incubation shows that organic matter mineralization and sediment-water NH{4/+} exchange had been stimulated by C. fluminea bioturbation and bioirrigation during the experiment. Therefore, C. fluminea activities such as excretion, burrowing, irrigation and turbation can effectively alter nitrogen dynamics and accelerate and stimulate nitrogen exchange and cycling at the sediment-water interface.

  20. Genetic damage in the bivalve mollusk Corbicula fluminea induced by the water-soluble fraction of gasoline.

    PubMed

    Fedato, R P; Simonato, J D; Martinez, C B R; Sofia, S H

    2010-07-19

    Although gasoline is an important contaminant of aquatic ecosystems, information concerning the potential effects of this petroleum derivative on the DNA of aquatic biota is lacking. The present study aimed to evaluate the genotoxic and mutagenic effects of acute exposures (6, 24, and 96h) to gasoline water-soluble fraction (GWSF), diluted to 5%, on the Asian clam Corbicula fluminea. The comet assay and the micronucleus (MN) test were performed on hemocytes and gill cells of C. fluminea. For the three different times tested, the comet assay indicated DNA damage in hemocytes and gill cells of C. fluminea exposed to GWSF. The MN test detected significant damage in the genetic material of the hemocytes only after 96h of exposure to GWSF. The recovery capacity of organisms previously exposed for 6h to GWSF was also evaluated with the comet assay. The results revealed a great capacity of this species to repair DNA damage; following 6h of recovery, the comet score returned to that of the control groups. Overall, our findings indicate that GWSF has genotoxic and mutagenic effects on C. fluminea. In addition, the present results confirm the sensitivity of C. fluminea to damage caused by exposure to environmental contaminants, and, therefore, its suitability for use in environmental monitoring studies. PMID:20510386

  1. Recovery of Waterborne Cryptosporidium parvum Oocysts by Freshwater Benthic Clams (Corbicula fluminea)

    PubMed Central

    Graczyk, Thaddeus K.; Fayer, Ronald; Cranfield, Michael R.; Conn, David Bruce

    1998-01-01

    Asian freshwater clams, Corbicula fluminea, exposed for 24 h to 38 liters of water contaminated with infectious Cryptosporidium parvum oocysts (1.00 × 106 oocysts/liter; approximately 1.9 × 105 oocysts/clam) were examined (hemolymph, gills, gastrointestinal [GI] tract, and feces) on days 1, 2, 3, 7, and 14 postexposure (PE). No oocysts were detected in the water 24 h after the contamination event. The percentage of oocyst-containing clams varied from 20 to 100%, depending on the type of tissue examined and the technique used—acid-fast stain (AFS) or immunofluorescent antibody (IFA). The oocysts were found in clam tissues and feces on days 1 through 14 PE; the oocysts extracted from the tissues on day 7 PE were infectious for neonatal BALB/c mice. Overall, the highest number of positive samples was obtained when gills and GI tracts were processed with IFA (prevalence, 97.5%). A comparison of the relative oocyst numbers indicated that overall, 58.3% of the oocysts were found in clam tissues and 41.7% were found in feces when IFA was used; when AFS was used, the values were 51.9 and 48.1%, respectively. Clam-released oocysts were always surrounded by feces; no free oocysts or oocysts disassociated from fecal matter were observed. The results indicate that these benthic freshwater clams are capable of recovery and sedimentation of waterborne C. parvum oocysts. To optimize the detection of C. parvum oocysts in C. fluminea tissue, it is recommended that gill and GI tract samples be screened with IFA (such as that in the commercially available MERIFLUOR test kit). PMID:9464376

  2. Biomonitoring of tin and arsenic in different compartments of a limnic ecosystem with emphasis on Corbicula fluminea and Dikerogammarus villosus.

    PubMed

    Sebesvari, Zita; Ettwig, Katharina Friederike; Emons, Hendrik

    2005-03-01

    Asian clam Corbicula fluminea, the amphipod Dikerogammarus villosus and the macrophyte Nuphar lutea were tested for investigating spatial and temporal variability in the bioavailability of tin and arsenic in the River Lippe, Germany. Samples were collected from September 2002 to May 2003 at a tin polluted site (source pollution) and a reference site. Additional screening sampling was carried out twice in April 2003 to test the extent of As and Sn concentration in periphyton (aufwuchs) samples. Accumulated Sn and As concentrations were measured with ICP-MS after sample processing (dissection, cryo-milling) and digestion. Quality control was performed by parallel analysis of three certified reference materials. Measurable As and Sn contents in plant tissues were only detectable in roots (below 30 microg kg(-1) and 20 microg kg(-1) for As and Sn, respectively). Homogenates from C. fluminea and D. villosus tissues showed site-dependent trace metal contents. Elevated bioavailability of Sn is present downstream of the sewage discharge of the world's biggest producer of tributyltin (TBT) at Luenen (northern Ruhr region). In comparison to C. fluminea, D. villosus shows higher concentrations of tin in samples from both sites. Arsenic concentrations in C. fluminea remain constant with increasing shell size, whereas tin shows a size-dependent accumulation. The results indicate that Corbicula fluminea and Dikerogammarus villosus are suitable passive biomonitoring organisms for Sn, but As levels might be actively regulated. The concentration of tin in the periphyton (aufwuchs) samples was found to be much higher in samples from a contaminated site (428 +/- 63 vs. 1949 +/- 226 microg kg(-1)). PMID:15735779

  3. 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.

  4. 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.

  5. 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. PMID:25017714

  6. 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.

  7. 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.

  8. Sequencing and De Novo Assembly of the Asian Clam (Corbicula fluminea) Transcriptome Using the Illumina GAIIx Method

    PubMed Central

    Chen, Huihui; Zha, Jinmiao; Liang, Xuefang; Bu, Jihong; Wang, Miao; Wang, Zijian

    2013-01-01

    Background The Asian clam (Corbicula fluminea) is currently one of the most economically important aquatic species in China and has been used as a test organism in many environmental studies. However, the lack of genomic resources, such as sequenced genome, expressed sequence tags (ESTs) and transcriptome sequences has hindered the research on C. fluminea. Recent advances in large-scale RNA-Seq enable generation of genomic resources in a short time, and provide large expression datasets for functional genomic analysis. Methodology/Principal Findings We used a next-generation high-throughput DNA sequencing technique with an Illumina GAIIx method to analyze the transcriptome from the whole bodies of C. fluminea. More than 62,250,336 high-quality reads were generated based on the raw data, and 134,684 unigenes with a mean length of 791 bp were assembled using the Velvet and Oases software. All of the assembly unigenes were annotated by running BLASTx and BLASTn similarity searches on the Nt, Nr, Swiss-Prot, COG and KEGG databases. In addition, the Clusters of Orthologous Groups (COGs), Gene Ontology (GO) terms and Kyoto Encyclopedia of Gene and Genome (KEGG) annotations were also assigned to each unigene transcript. To provide a preliminary verification of the assembly and annotation results, and search for potential environmental pollution biomarkers, 15 functional genes (five antioxidase genes, two cytochrome P450 genes, three GABA receptor-related genes and five heat shock protein genes) were cloned and identified. Expressions of the 15 selected genes following fluoxetine exposure confirmed that the genes are indeed linked to environmental stress. Conclusions/Significance The C. fluminea transcriptome advances the underlying molecular understanding of this freshwater clam, provides a basis for further exploration of C. fluminea as an environmental test organism and promotes further studies on other bivalve organisms. PMID:24244519

  9. 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. PMID:18284151

  10. 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

  11. Size-dependent effects of low level cadmium and zinc exposure on the metabolome of the Asian clam, Corbicula fluminea.

    PubMed

    Spann, Nicole; Aldridge, David C; Griffin, Julian L; Jones, Oliver A H

    2011-10-01

    The toxic effects of low level metal contamination in sediments are currently poorly understood. We exposed different sized Asian clams, Corbicula fluminea, to sediment spiked with environmentally relevant concentrations of either zinc, cadmium or a zinc-cadmium mixture for one week. This freshwater bivalve is well suited for sediment toxicity tests as it lives partly buried in the sediment and utilises sediment particles as a food resource. After one week, the whole tissue composition of low molecular weight metabolites was analysed by nuclear magnetic resonance spectroscopy (NMR) and gas chromatography-mass spectrometry (GC-MS). The condition index (ratio of tissue dry weight to volume inside the shell valves) was also measured. Small and large clams were clearly differentiated by their metabolic composition and the two size classes showed opposite responses to the mixture spiked sediment. No effects of zinc alone on the metabolome were found and cadmium only influenced the smaller size class. The main perturbations were seen in amino acid and energy metabolism, with small clams using amino acids as an energy resource and larger clams primarily drawing on their larger storage reserves of carbohydrates. Our study demonstrates that metabolomics is a useful technique to test for low level toxicity which does not manifest in mortality or condition index changes. The differing effects between the two size classes stress that it is important to consider age/size when conducting metabolomic and ecotoxicology assessments, since testing for the effects on only one size class makes it more difficult to extrapolate laboratory results to the natural environment. PMID:21946168

  12. 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.

  13. 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.

  14. 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. PMID:26774961

  15. 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

  16. 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

    2014-01-01

    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

  17. Metallothionein response to cadmium and zinc exposures compared in two freshwater bivalves, Dreissena polymorpha and Corbicula fluminea.

    PubMed

    Marie, Véronique; Gonzalez, Patrice; Baudrimont, Magalie; Bourdineaud, Jean-Paul; Boudou, Alain

    2006-08-01

    Metallothionein (MT) response to cadmium (Cd) and zinc (Zn) bioaccumulation after single or combined direct exposure was compared in two freshwater bivalves, Dreissena polymorpha (zebra mussel) and Corbicula fluminea (Asiatic clam). Bivalves were exposed to 0.133 microM Cd and/or 15.3 microM Zn, with metal and MT concentrations analysed in the whole soft body after 1, 3, 10 and 24 days of exposure and compared with controls. Results showed significant increase in MT concentrations in both species exposed to Cd and Cd+Zn with a higher accumulation of the protein compared to the control in D. polymorpha for nevertheless similar Cd levels accumulated with time. Exposure to Zn alone led to a significant increase in MT concentrations only in C. fluminea, whereas there was a lack of MT gene induction in the zebra mussels which was confirmed by MT mRNA quantification in gills (RT-PCR). Mussel mortality after 10 days of exposure to Zn and Cd + Zn is discussed with regard to detoxification mechanisms, which include metallothioneins. PMID:16841249

  18. A real-time biomonitoring system to detect arsenic toxicity by valve movement in freshwater clam Corbicula fluminea.

    PubMed

    Chen, Wei-Yu; Jou, Li-John; Chen, Suz-Hsin; Liao, Chung-Min

    2012-05-01

    Arsenic (As) is the element of greatest ecotoxicological concern in aquatic environments. Effective monitoring and diagnosis of As pollution via a biological early warning system is a great challenge for As-affected regions. The purpose of this study was to synthesize water chemistry-based bioavailability and valve daily rhythm in Corbicula fluminea to design a biomonitoring system for detecting waterborne As. We integrated valve daily rhythm dynamic patterns and water chemistry-based Hill dose-response model to build into a programmatic mechanism of inductance-based valvometry technique for providing a rapid and cost-effective dynamic detection system. A LabVIEW graphic control program in a personal computer was employed to demonstrate completely the functional presentation of the present dynamic system. We verified the simulated dissolved As concentrations based on the valve daily rhythm behavior with published experimental data. Generally, the performance of this proposed biomonitoring system demonstrates fairly good applicability to detect waterborne As concentrations when the field As concentrations are less than 1 mg L(-1). We also revealed that the detection times were dependent on As exposure concentrations. This biomonitoring system could particularly provide real-time transmitted information on the waterborne As activity under various aquatic environments. This parsimonious C. fluminea valve rhythm behavior-based real-time biomonitoring system presents a valuable effort to promote the automated biomonitoring and offers early warnings on potential ecotoxicological risks in regions with elevated As exposure concentrations. PMID:22359017

  19. 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)

  20. 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.

  1. 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

  2. A freshwater bioprobe: Periostracum of the Asian Clam, Corbicula fluminea (Müller) combined with laser microprobe mass spectrometer.

    PubMed

    Hutchinson, P J; Rollins, H; Sharkey, A G; Prezant, R S; Kim, Y; Hercules, D M

    1993-01-01

    A freshwater bioprobe, combining the Asiatic Clam, Corbicula fluminea (Müller) and the laser microprobe mass spectrometer (LAMMA), can determine anthropogenic chemical contamination of freshwater systems. Laser generated mass spectra from the periostracal layers of clams contaminated with either a salt, potassium bromide, or an aromatic compound, phenol, produce distinctive mass spectral signatures that are different from uncontaminated clams. Uncontaminated clams have characteristic signatures with distinctive spectral peaks less than m/z 41; while exposed clams have many strong peaks well above this m/z. This freshwater bioprobe, using LAMMA to analyze the surface of clams, can be used as a screening tool for monitoring the water-treatment systems, for determining the source of contaminated baseflow and return flow discharge to streams, and for monitoring the water chemistry of a body of water. This system exploits the facility of using the shell instead of soft tissue with the LAMMA and has potential to detect anthropogenically-derived chemical stress. PMID:15091918

  3. 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.

  4. Sensitivity of the invasive bivalve Corbicula fluminea to candidate control chemicals: The role of dissolved oxygen conditions.

    PubMed

    Rosa, Inês C; Garrido, Rita; Ré, Ana; Gomes, João; Pereira, Joana L; Gonçalves, Fernando; Costa, Raquel

    2015-12-01

    The freshwater Corbicula fluminea is a major aquatic nuisance worldwide. Current pest control methods raise cost-effectiveness and environmental concerns, which motivate research into improved mitigation approaches. In this context, the susceptibility of the clams to chemicals under reduced oxygen conditions was examined. Biocides with different mechanisms of toxicity (niclosamide, polyDADMAC, ammonium nitrate, potassium chloride and dimethoate) were tested under normoxic (>7 mg L(-1) dissolved O2) and hypoxic (<2 mg L(-1) dissolved O2) conditions. Hypoxia was observed to potentiate chemical treatment, particularly when combined with non-overwhelming doses that would produce only intermediate responses by themselves. For niclosamide, ammonium nitrate and dimethoate, clam mortality enhancements up to 400% were observed under hypoxia as compared to dosing upon normal dissolved oxygen conditions. For polyDADMAC and potassium chloride, substantially lower mortality enhancements were found. The differences in the clams' sensitivity to the chemicals under hypoxia could be linked to the expected mechanisms of action. This suggests that judicious selection of the biocide is essential if optimized combined control treatments are to be designed and provides an insight into the interference of frequent hypoxia events in the response of natural clam populations to contaminant loads. PMID:26254082

  5. 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.

  6. Induction of a multixenobiotic resistance protein (MXR) in the Asiatic clam Corbicula fluminea after heavy metals exposure.

    PubMed

    Achard, M; Baudrimont, M; Boudou, A; Bourdineaud, J P

    2004-05-12

    Multixenobiotic resistance mechanisms (MXR) related to the mammalian P-glycoprotein multidrug transporter protein (P-gp) are known to occur in several marine invertebrates. In the present work, we report on the induction of an MXR protein by various heavy metals in the gills of the freshwater clam Corbicula fluminea. The evaluation of the MXR protein level was assessed by Western blot using a specific monoclonal antibody raised against the human P-gp (C219). A field transplantation experiment, where clams were caged in a gradient relative to an industrial site, demonstrated a positive relationship between MXR levels and (a) metal pollution (Cd and Zn) in the environment and (b) metal bioaccumulation in the gills. To establish this correlative relationship, clams were exposed to different levels of cadmium (15-60 microg l(-1)) for up to 15 days in a controlled laboratory experiment. MXR protein levels increased in time for all treatments (including the control). However, the highest levels of MXR protein titer were expressed in clams that had been exposed to the lowest dose of cadmium. The causes for this observed inverse relationship between the exposure dose and the MXR induction is discussed. MXR protein titer was also shown to be induced by other heavy metals (zinc, inorganic mercury, and copper). PMID:15084411

  7. A freshwater clam (Corbicula fluminea) extract improves cholesterol metabolism in rats fed on a high-cholesterol diet.

    PubMed

    Chijimatsu, Takeshi; Tatsuguchi, Iwao; Abe, Kazuaki; Oda, Hiroaki; Mochizuki, Satoshi

    2008-10-01

    The effect of a freshwater clam (Corbicula fluminea) extract (FCE) on cholesterol metabolism in rats fed on a high-cholesterol diet was investigated. When rats were fed various amounts of FCE in addition to the high-cholesterol diet for 2 wk, the serum and hepatic cholesterol levels were gradually reduced in a dose-dependent manner, as compared with the control group. The excretion of neutral sterols and bile acids into the feces was increased by feeding FCE. Several phytosterols were detected in the feces of rats fed on the FCE-containing diet. In addition, substantial amounts of phytosterols were found in FCE. Cholesterol 7alpha-hydroxylase (CYP7A1) mRNA in the liver of the rats fed on the FCE-containing diets was higher than that of rats fed on the high-cholesterol diets without FCE. These results may suggest that enhanced cholesterol degradation and the excretion of neutral sterols and bile acids contributed to the hypocholesterolemic effect of FCE observed in the hypercholesterolemic rats fed on the high-cholesterol diet. PMID:18838816

  8. 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. PMID:21333740

  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. 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.

  11. 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.

  12. 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. PMID:25499240

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

    NASA Astrophysics Data System (ADS)

    Franco, J. N.; Ceia, F. R.; Patrício, J.; Modesto, V.; Thompson, J.; Marques, J. C.; Neto, J. M.

    2012-10-01

    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.

  14. 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.

  15. 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. PMID:19463028

  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

    2015-03-01

    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. PMID:25463214

  17. 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.

  18. 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.

  19. What are the outcomes of an industrial remediation on a metal-impacted hydrosystem? A 2-year field biomonitoring of the filter-feeding bivalve Corbicula fluminea.

    PubMed

    Arini, A; Daffe, G; Gonzalez, P; Feurtet-Mazel, A; Baudrimont, M

    2014-08-01

    The Riou-Mort watershed (southwest France) exhibits high metal contaminations (Cd and Zn) related to an important mining past. In this context, a remediation process has been implemented in 2007 to reduce the watershed contamination. The aim of this study was to assess the early effectiveness of the remediation process on the hydrosystem contamination state. A biomonitoring was realized over two years (2008-2010) with the filter-feeding bivalve Corbicula fluminea, exposed along a contamination gradient. Several biological parameters were monitored: (1) Cd and Zn bioaccumulation, (2) Metallothionein (MT) production as detoxification mechanism, (3) differential gene expression (cat, sod, gst, 12S, cox1, mt). The physicochemical data highlighted strong metal contamination persistence in the river water and failed to demonstrate a significant decrease of metal contamination during the 2-year monitoring. The bioaccumulation results confirmed the persistence of a water contamination despite remediation works, with maximum values measured downstream from the industrial site (Joany). The bioaccumulation increased in 2010, reaching 69.3±5.3 μg Cd g(-1) DW at Joany in July 2010, whereas it did not exceed 1.4±0.2 μg Cd g(-1) DW at the reference site throughout the biomonitoring. MT concentrations were closely related to the contamination gradient, especially at Joany, demonstrating their strong involvement in the detoxification processes. The mt gene induction was strongly correlated to the MT and metal concentrations. The gene inductions of cat, sod, gst and 12S were correlated to both the metal concentrations and the seasonal variations, especially temperatures. This suggests that environmental factors require serious consideration for the interpretation of bioaccumulation kinetics and thus for the assessment of the remediation effectiveness. Consequently, the whole results did not yet highlight strong beneficial effects of remediation work on the hydrosystem

  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. PMID:26151653

  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

    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.

  5. 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

  6. 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...

  7. 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 ...

  8. 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. PMID:15862580

  9. 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.

  10. 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

  11. 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

  12. 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. PMID:25704646

  13. 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.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  15. 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.

  16. 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.

  17. 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.

  18. Rapid evolution of sessility in an endemic species flock of the freshwater bivalve Corbicula from ancient lakes on Sulawesi, Indonesia

    PubMed Central

    von Rintelen, Thomas; Glaubrecht, Matthias

    2005-01-01

    The fauna of ancient lakes frequently contains taxa with highly derived morphologies that resulted from in situ radiation of lacustrine lineages with high antiquity. We employed a molecular mtDNA phylogeny to investigate this claim for corbiculid freshwater bivalves in two ancient lake systems on the Indonesian island Sulawesi. Among the otherwise mobile corbiculid species flock, only one taxon, Posostrea anomioides, in the ancient Lake Poso exhibits a unique habit, i.e. cementing one valve to the substrate. Our data show that Corbicula on Sulawesi is polyphyletic, with the endemic riverine taxa in terminal position, and the lacustrine species flock being paraphyletic. Surprisingly, Posostrea is not confirmed as a genus distinct from Corbicula and genetic distances suggest a rather recent origin from the only other corbiculid species endemic to Lake Poso, the non-cementing Corbicula possoensis. While the cementing anomioides, despite its unique behavioural and morphological characteristics, clusters together with non-sessile Corbicula species, the latter exhibit strong genetic distances in the absence of morphological disparity and fall into several genetically rather distinct clades. These findings suggest that developmental plasticity of animals in ancient lakes rather than the antiquity of lineages might account for the unique morphology of some species. PMID:17148330

  19. 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...

  20. 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.

  1. 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.

  2. 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., Jr.

    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.

  3. 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.

  4. 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.

  5. 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. PMID:25455471

  6. 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.

  7. 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. PMID:27238016

  8. 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

  9. 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

  10. 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.

  11. 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. PMID:26327634

  12. 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. PMID:24507146

  13. 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. PMID:22398861

  14. 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.

  15. 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. PMID:20567812

  16. 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

  17. 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.

  18. 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.

  19. Sensory determinants of valve rhythm dynamics provide in situ biodetection of copper in aquatic environments.

    PubMed

    Jou, Li-John; Chen, Bo-Ching; Chen, Wei-Yu; Liao, Chung-Min

    2016-03-01

    This study successfully applied an improved valvometry technique to measure waterborne copper (Cu), based on valve activity dynamics of the freshwater clam Corbicula fluminea. The improved valvometry technique allows the use of free-range bivalves and avoids causing stresses from experimental artifacts. The proposed daily valve rhythm models and a toxicodynamics-based Hill model were linked to predict valve dynamic responses under different Cu exposures with a circadian valve rhythm endpoint. Cu-specific detection threshold was 5.6 (95 % CI 2.1-9.3) and 19.5 (14.6-24.3) μg L(-1) for C. fluminea, based on response times of 300 and 30 min, respectively. Upon exposure to Cu concentrations in excess of 50 μg L(-1), the alteration of valve rhythm behavior was correlated with Cu concentration within 30 min, indicating notable sensing ability. This study outlines the feasibility of an in situ early warning dynamic biomonitoring system for detection of waterborne Cu based on circadian valve activities of C. fluminea. PMID:26564192

  20. 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.

  1. Accumulation of selenium in benthic bivalves and fine-grained sediments of San Francisco Bay, the Sacramento-San Joaquin Delta, and selected tributaries, 1984-1986

    USGS Publications Warehouse

    Johns, C.; Luoma, S.N.

    1987-01-01

    Fine-grained, oxidized, surface sediments and two benthic bivalves (Corbicula sp., a suspension-feeding freshwater clam, and Macoma balthica, a deposit-feeding brackish water clam) were used to examine spatial distributions of selenium within San Francisco Bay and the Sacramento/San Joaquin River Delta and to compare riverine with local inputs of biologically available selenium to this large, complex, urbanized estuary. Selenium concentrations in Corbicula were elevated in the western Delta and northern reach of San Francisco Bay compared to concentrations in Corbicula from river systems not enriched in selenium. Biologically available selenium did not appear to enter the southern Delta or northern reach of the Bay from the San Joaquin River, a possible source, in levels that could measurably influence bioaccumulation by Corbicula. Selenium concentrations in Macoma balthica also were elevated in southern South San Francisco Bay and near the western edge of Suisun Bay.

  2. 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.

  3. [Macrobenthic community structure and bioassessment for water quality of Banqiao Reservoir in Huaihe River basin].

    PubMed

    Sun, Wei-sheng; Gu, Qian-hong; Dong, Jing; Cheng, Qing-qing; Li, Xue-jun; Zhang, Man

    2015-09-01

    In order to demonstrate macrobenthic community structure dynamics and conduct a biological evaluation of water quality in Banqiao Reservoir, we collected seasonal samples from January to November 2014 across 15 sampling sites. A total of 17 species belonging to five families, four classes, and 3 phyla were identified, including 8 chironomidae, 4 oligochaeta and 5 mollusc. Bellamya aeruginosa, Corbicula fluminea, Branchiura sowerbyi, Pelopia sp. and Glyptotendipes sp. were the important species in Banqiao Reservoir. The total density, biomass and biodiversity of marobenthos showed significant spatial and temporal differences. ANOSIM analysis indicated that the macrobenthic community structure also differed significantly among regions and seasons, and the main contributing species were Glyptotendipes sp., Pelopia sp. and B. sowerbyi. The abundance-biomass comparison curves (ABC curves) indicated that the current macrobenthic community in Banqiao Reservoir was stable. Combined with the biodiversity index, biological pollution index (BPI) and Hilsenhoff biotic index (BI), it was suggested that Banqiao Reservoir suffered slight pollution. PMID:26785570

  4. A diagnostic molecular marker for zebra mussels (Dreissena polymorpha) and potentially co-occurring bivalves: mitochondrial COI.

    PubMed

    Baldwin, B S; Black, M; Sanjur, O; Gustafson, R; Lutz, R A; Vrijenhoek, R C

    1996-03-01

    We report diagnostic differences in the nucleotide sequences of a 710-bp fragment of the mitochondrial cytochrome c oxidase subunit I gene (COI) from the zebra mussel (Dreissena polymorpha) and potentially co-occurring bivalves: the quagga mussel (Dreissena bugensis); the Asiatic clam (Corbicula fluminea), the dark false mussel (Mytilopsis leucophaeata), and the wedge clam (Rangia cuneata). The COI sequence of the deep-water "profunda" phenotype of the quagga mussel was nearly identical to that of shallow-water quagga mussels. Restriction fragment length polymorphisms (RFLPs) in this portion of COI produced species-specific differences in fragment numbers and sizes that could be used as diagnostic markers to distinguish the free-living larvae produced by these bivalves. PMID:8869514

  5. 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.

  6. 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.

  7. 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.

  8. 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. PMID:20369380

  9. 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

  10. 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

  11. 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

  12. Effects of benthic macrofauna bioturbation on the bacterial community composition in lake sediments.

    PubMed

    Zeng, Jin; Zhao, Da-Yong; Liu, Peng; Yu, Zhong-Bo; Huang, Rui; Wu, Qinglong L

    2014-08-01

    Benthic macrofauna are considered to be an important part of the lacustrine ecosystem, and bioturbation may greatly affect the biogeochemical processes and microbial activities in sediments. In the present study, the bacterial community composition in sediments inhabited by 3 different types of benthic macrofauna (Corbicula fluminea, Chironomidae larvae, and tubificid worms) in the shallow and eutrophic Lake Taihu was studied to investigate the different effects of bioturbation on the composition of these communities. Microcosms were constructed, and culture-independent methods, including terminal restriction fragment length polymorphism (T-RFLP) and clone library analysis, were performed to evaluate the bacterial communities. Analysis of similarities (ANOSIM) and multidimensional scaling (MDS) analysis of T-RFLP patterns demonstrated that differences in the bacterial community composition between the control and the macrofauna-inhabited sediments were not as great as expected, although the chemical properties of the sediments changed remarkably. Nevertheless, the dominant bacterial group in each type of macrofauna-inhabited sediment was different. Acidobacteria, Betaproteobacteria, and Deltaproteobacteria were the dominant bacterial groups in sediments inhabited by C. fluminea, tubificid worms, and Chironomidae larvae, respectively. The data obtained in this study are helpful for understanding the effects of bioturbation in a shallow, eutrophic lake. PMID:25070418

  13. 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. PMID:27227330

  14. 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.

  15. Field and laboratory assessment of a coal processing effluent in the Leading Creek Watershed, Meigs County, Ohio.

    PubMed

    Kennedy, A J; Cherry, D S; Currie, R J

    2003-04-01

    The U.S. Environmental Protection Agency has not recommended water quality criteria (WQC) to protect aquatic life from elevated sodium and sulfate concentrations, such as those associated with the coal-processing effluent of Meigs County Mine #31. This discharge, received by a tributary of the Leading Creek Watershed (SE Ohio), had a mean specific conductivity (SC) of 8,109 (7,750-8,750) microS/cm and total metal concentrations below acute WQC. The mean 48-h LC(50) for Ceriodaphnia dubia in the effluent was 6,713 +/- 99 microS/cm; mean 48-h survival was 44% for study sites downstream of the effluent. The best indicators of impairment used in this study were Ceriodaphnia fecundity, in situ Corbicula fluminea growth, EPT minus Hydropsychidae (richness and relative abundance), and relative Ephemeroptera abundance. Mayflies, reduced by more than 99% below the effluent, were absent from all but the furthest downstream study site. SC was strongly correlated with Corbicula growth (r = -0.9755, p = 0.0009) and EPT minus Hydropsychidae richness (r = -0.8756, p < 0.0001), suggesting the effluent was primarily responsible for biotic impairment. Our results indicated that SC levels, a measure of dissolved solids, in the Leading Creek Watershed that exceeded approximately 3,700 microS/cm impaired sensitive aquatic fauna. PMID:12712291

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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…

  2. Motivational Influences on Transfer

    ERIC Educational Resources Information Center

    Pugh, Kevin J.; Bergin, David A.

    2006-01-01

    Both transfer and motivation are important constructs accompanied by extensive bodies of literature. However, there is a lack of integration of the 2 constructs. This article analyzes the potential indirect influence of motivational factors on transfer by reviewing studies that examine the influence of motivation on cognitive processes related to…

  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. Can Television Influence People?

    ERIC Educational Resources Information Center

    Comstock, George

    1985-01-01

    Discusses simultaneous airing by three commercial networks and influence on viewers' attitudes of The Great American Values Test, a 30-minute informational program designed to affect viewers' values about environmental issues, racial equality, and sexual equality. The program's effectiveness at influencing behavior was proven by a field…

  5. 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. PMID:25666736

  6. Influences in Curriculum Change.

    ERIC Educational Resources Information Center

    Unruh, Glenys G., Ed.; Leeper, Robert R., Ed.

    This report contains conference addresses that (1) deal with social and psychological forces influencing curriculum change and (2) discuss actual changes now taking place in a number of subject fields. Insights into the forces acting on the curriculum are presented by the authors of Part I. Arthur W. Foshay challenges educators to recognize the…

  7. 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…

  8. 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. PMID:20952043

  9. 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. PMID:27262191

  10. 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. PMID:26943904

  11. 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.

  12. Amendments for the in situ remediation of contaminated sediments: evaluation of potential environmental impacts.

    PubMed

    Paller, Michael H; Knox, Anna S

    2010-09-15

    Active sediment caps represent a comparatively new technology for remediating contaminated sediments. They are made by applying chemically active amendments that reduce contaminant mobility and bioavailability to the sediment surface. The objective of this study was to determine if active cap amendments including organoclay, apatite, and biopolymers have the potential to harm benthic organisms. Methods included laboratory bioassays of amendment toxicity and field evaluations of amendment impacts on organisms held in cages placed within pilot-scale active caps located in Steel Creek, a South Carolina (USA) stream. Test organisms included Hyalella azteca, Leptocheirus plumulosus, Lumbriculus variegatus, and Corbicula fluminea to represent a range of feeding modes, burrowing behaviors, and both fresh and saltwater organisms. In addition to the laboratory and field assays, chemical extractions were performed to determine if the amendments contained harmful impurities that could leach into the ambient environment. Laboratory bioassays indicated that 100% apatite had minimal effects on Hyalella in freshwater and up to 25% organoclay was nontoxic to Leptocheirus in brackish water. Field evaluations indicated that pilot-scale caps composed of up to 50% apatite and 25% organoclay did not harm Hyalella, Lumbriculus, or Corbicula. In contrast, organisms in caps containing biopolymers died because of physical entrapment and/or suffocation by the viscous biopolymers. The extractions showed that the amendments did not release harmful concentrations of metals. These studies indicated that apatite and organoclay are nontoxic at concentrations (up to 50% and 25% by weight, respectively) needed for the construction of active caps that are useful for the remediation of metals and organic contaminants in sediments. PMID:20655093

  13. Family Influences and Unconscious Drives.

    ERIC Educational Resources Information Center

    English, Fanita

    2001-01-01

    Drives for survival, expression, and quiescence influence early human development and continue to influence career development throughout life. Turmoil may arise when a drive conflicts with others or is suppressed by other drives. (SK)

  14. Nutritional influences on folliculogenesis.

    PubMed

    Hernandez-Medrano, J H; Campbell, B K; Webb, R

    2012-08-01

    Folliculogenesis is an intricate process that involves the proliferation and differentiation of both somatic and germ cells. This process depends on complex interactions between systemic factors such as both pituitary gonadotrophins and metabolic hormones and/or local factors produced by the ovarian somatic and germ cells, such as the IGF system and TGF-β superfamily members. In domestic ruminants, follicular development begins during foetal life with formation of primordial follicles from the association of germ cells and pre-granulosa cells. After follicular formation, folliculogenesis begins with a primordial follicle progressing into more developed stages (i.e. primary, secondary, pre-antral and antral) in a continuous, progressive process to either ovulation or, as in most cases, to atresia. Even early stages of follicular formation and subsequent development are influenced by both internal (e.g. genotype) and/or external environmental (e.g. nutrition and season) factors. Among these external factors, nutrition is one of the most important affecting reproductive function, and this is the focus of this review, because other reviews in this issue discuss other environmental factors. A number of studies have now shown that nutrition can have both positive and negative effects on follicular growth, oestrous activity, oocyte quality, blastocyst development and pregnancy outcome. Therefore, understanding the intricate processes involved during folliculogenesis and the ways in which factors, such as nutrition, affect them is leading to new opportunities to improve pregnancy rates by influencing follicle development and oocyte quality. This review will focus on follicular development from foetal to adult stages and the influences that nutrition has during some of these developmental stages. PMID:22827381

  15. Microbiologically influenced corrosion testing

    SciTech Connect

    Kearns, J.R.; Little, B.J.

    1994-01-01

    This symposium was held November 16--17, 1992 in Miami, Florida. The purpose of the symposium was to provide a forum for state-of-the-art information on the effects of microorganisms on the corrosion of metals. Many industrial needs in the area of microbial influenced corrosion testing are identified in the presentations along with latest laboratory and field testing techniques. Strategies to monitor and control corrosion and biofouling in water distribution systems, underground pipelines, buildings, and marine vessels are discussed. Individual papers have been processed separately for inclusion in the appropriate data bases.

  16. 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.…

  17. Influencing the legislative process

    SciTech Connect

    Martin, H.

    1994-12-31

    This basic premise--that environmental policy results from a multitude of responses to a variety of problems--explains to some extent the general lack of coordination between major environmental protection programs. It also suggests why there has been so much new legislation and regulation in the last decade and a half. Solutions have been proposed and adopted to address a myriad of problems, from leaking underground storage tanks to catastrophic releases of toxic materials. In the absence of broader environmental goals or policy, these individual solutions often gain a life of their own and their passage becomes a high priority for their sponsors. Given this situation, the best way an individual can influence environmental policy is to become involved in solving a problem--in making one`s voice heard in the decision-making process. But influencing the outcome of a decision-making process can be difficult at best, and is impossible without an understanding of the process itself.In addition to knowing the process, it is also important to understand the role played by the professionals involved in the process, the way in which decision makers view the world, and the ways in which a position or opinion on a particular issue can be best brought to the attention of decision makers.

  18. The levers of influence.

    PubMed

    Martin, W

    1999-01-01

    Physicians often determine the demand for health care services, as well as control the clinical processes aimed at improving health outcomes at the individual and population level. Given their important role in enhancing health status and improving the health care delivery system, it is critical that physician executives master the tools necessary to positively influence physician behavior. But changing behavior is far more complex than "doing it or not doing it." The Nike slogan "just do it" is motivating, but over-simplified. The roots of human change include: consciousness-raising, emotional arousal, commitment, helping relationships, self-reevaluation, reward, and environmental control. A model to effectively influence behavior is presented and includes setting clear expectations, measuring and monitoring performance, providing feedback, and rewarding and recognizing improvement. If all else fails, try discipline. This five-step approach is based on the science of human behavior and working with physicians in diverse settings, ranging from academic medical centers to small practices. PMID:10788108

  19. Orientation on understanding interpersonal influence.

    PubMed

    Strickland, B; Arnn, J

    1977-09-01

    Everyone influences and is influenced by others. Are you satisfied with the impact your influence has on others? If not, it can be changed by examining and working on the dimensions of your "style of influence," such as activity, visibility, involvement, and productivity. The author analyzes some of the opposites on a spectrum or "wheel of influence," showing how they may be melded by moderation to achieve the kind of impact you may wish. For instance, there is the analyzer vs. the performer, the leader vs. the follower, the experimenter vs. the organizer, and the asserter vs. the listener. As modes of influence, extremes in any dimension are self-defeating, but by balancing aspects of both sides, desirable "compromises" can be developed. Should you wish to change your style of influence, helfpful procedures to follow are suggested, which, hopefully, will result in satisfying interpersonal relationships and understanding. PMID:886127

  20. 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. PMID:24730171

  1. Corporate influences on epidemiology.

    PubMed

    Pearce, Neil

    2008-02-01

    Corporate influences on epidemiology have become stronger and more pervasive in the last few decades, particularly in the contentious fields of pharmacoepidemiology and occupational epidemiology. For every independent epidemiologist studying the side effects of medicines and the hazardous effects of industrial chemicals, there are several other epidemiologists hired by industry to attack the research and to debunk it as 'junk science'. In some instances these activities have gone as far as efforts to block publication. In many instances, academics have accepted industry funding which has not been acknowledged, and only the academic affiliations of the company-funded consultants have been listed. These activities are major threats to the integrity of the field, and its survival as a scientific discipline. There is no simple solution to these problems. However, for the last two decades there has been substantial discussion on ethics in epidemiology, partly in response to the unethical conduct of many industry-funded consultants. Professional organizations, such as the International Epidemiological Association, can play a major role in encouraging and supporting epidemiologists to assert positive principles of how science should work, and how it should be applied to public policy decisions, rather than simply having a list of what not to do. PMID:18245050

  2. 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…

  3. 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.

  4. [Macrobenthos community structure and its relations with environmental factors in Taihu River basin].

    PubMed

    Gao, Xin; Niu, Cui-Juan; Hu, Zhong-Jun

    2011-12-01

    An investigation was conducted on the macrobenthos at 37 sampling sites in the Taihu River basin in August 2009 and May 2010. A total of 69 macrobenthos species were collected, of which, 15 species (21.7% of the total) were oligochaetas, 16 species (23.2%) were mollusks, 5 species (7.2%) were crustaceans, 27 species (39.1%) were aquatic insects, and 6 species (8.7%) were polychaetes. Based on the species composition and relative abundance, and by using two-way indicators species analysis (TWINSPAN) and detrended correspondence analysis (DCA), the 37 sampling sites were divided into four groups. In the first group, polychaetes and mollusks such as Nephthys sp. and Corbicula fluminea were the indicator species; in the second group, polychaetes and mollusks such as Grandidierella aihuensis and Semisulcospira libertina were the indicator species; in the third and fourth groups, the indicator species were the annelids such as Limnodrilus hoffmeisteri and the Tubifex tubifex and chironomidae larvae, respectively. The canonical correspondence analysis (CCA) indicated that water conductivity and total nitrogen were the main environmental factors affecting the distribution of macrobenthos, and the factors water depth, diaphaneity, COD(Cr), ammonium nitrogen, nitrate nitrogen, and chlorophyll a also had definite effects. PMID:22384605

  5. Effect of cage design on growth of transplanted Asian clams: implications for assessing bivalve responses in streams.

    PubMed

    Hull, Matthew S; Cherry, Donald S; Merricks, Timothy C

    2004-01-01

    This study was designed to determine whether survivorship and growth of Asian clams (Corbicula fluminea [Müller]) differed significantly between two types of field enclosures. Enclosures were either flexible mesh bags or rigid cages (hereto after referred as bioboxes) designed to homogenize substrate among study sites and accommodate Asian clam feeding mechanisms. For 96d, cages remained at 12 Clinch River (CR), Hurricane Fork (HF), and Dump's Creek (DC) sites upstream and downstream of a coal-fired power plant discharge, coal mining effluent, and coal combustion-related disposal facilities in Carbo, Virginia. Although survivorship was not significantly different between cage types, mean growth of clams in bioboxes was significantly greater overall (p = 0.0157). Despite the difference in growth between the two cage types, both confirmed significant reductions of survivorship and growth directly below the power plant discharge. Additionally, coefficient of variance values for biobox growth data were reduced at most study sites (averages of 16% for bioboxes versus 19% for mesh bags). Our results have implications toward strengthening weight-of-evidence approaches used to link impairment of transplanted bivalves to environmental contaminants. More importantly, these results suggest that ecotoxicological impairment of bivalves transplanted downstream of the coal-fired power plant discharge functioned independently of site-specific substrate provisions. PMID:15327146

  6. Effects of freshwater clam extract supplementation on time to exhaustion, muscle damage, pro/anti-inflammatory cytokines, and liver injury in rats after exhaustive exercise.

    PubMed

    Huang, Kuo-Chin; Wu, Wen-Tien; Yang, Fwu-Lin; Chiu, Yi-Han; Peng, Tai-Chu; Hsu, Bang-Gee; Liao, Kuang-Wen; Lee, Ru-Ping

    2013-01-01

    The potent anti-inflammatory activities and tissue-protective effects of freshwater clams (Corbicula fluminea) have been well reported. The aim of this study was to determine the effects of freshwater clam extract (FCE) supplementation on time to exhaustion, muscle damage, pro- and anti-inflammatory cytokines, and liver injury in rats after exhaustive exercise. Thirty-two rats were divided into four groups: sedentary control (SC); SC group with FCE supplementation (SC+FCE); exhaustive exercise (E); and E group with FCE supplementation (E+FCE). The SC+FCE and E+FCE groups were treated with gavage administration of 20 mg/kg for seven consecutive days. Blood samples were collected for the evaluation of biochemical parameters. The cytokine levels of TNF-α and IL-10 were also examined. Twenty-four hours after exhaustive exercise, the rat livers were removed for H & E staining. The FCE supplementation could extend the time to exhaustion in exercised rats. The levels of CPK, LDH, AST, ALT, lactate, TNF-α and H & E stains of the liver injury were significantly decreased in the E+FCE group, but the blood glucose and IL-10 were significantly higher in comparison with the E group. This study suggests that FCE supplementation may improve endurance performance and reduce exercise-induced muscle damage, inflammatory stress and liver injury. PMID:23531600

  7. Comparison of streambed sediment and aquatic biota as media for characterizing trace elements and organochlorine compounds in the Willamette Basin, Oregon

    USGS Publications Warehouse

    Wentz, D.A.; Waite, I.R.; Rinella, F.A.

    1998-01-01

    During 1992-93, 27 organochlorine compounds (pesticides plus total PCB) and 17 trace elements were analyzed in bed sediment and aquatic biota from 20 stream sites in the Willamette Basin as part of the U.S. Geological Survey's National Water-Quality Assessment Program. Data from each medium were compared to evaluate their relative effectiveness for assessing occurrence (broadly defined as documentation of important concentrations) of these constituents. Except for Cd, Hg, Se, and Ag, trace element concentrations generally were higher in bed sediment than in biota. Conversely, although frequencies of detection for organochlorine compounds in biota were only slightly greater than in bed sediment, actual concentrations in biota (normalized to lipid) were as much as 19 times those in sediment (normalized to organic carbon). Sculpin (Cottus spp.) and Asiatic clams (Corbicula fluminea), found at 14 and 7 sites, respectively, were the most widespread taxa collected during the study. Concentrations of trace elements, particularly As and Cu, were typically greater in Asiatic clams than in sculpin. In contrast, almost half of the organochlorine compounds analyzed were found in sculpin, but only DDT and its degradation products were detected in Asiatic clams; this may be related to the lipid content of sculpin, which was about three times higher than for clams. Thus, the medium of choice for assessing occurrence depends largely on the constituent(s) of interest.

  8. 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. PMID:26042840

  9. 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. PMID:25108183

  10. 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

  11. 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.

  12. Effects of flow reduction and spillways on the composition and structure of benthic macroinvertebrate communities in a Brazilian river reach.

    PubMed

    Maroneze, D M; Tupinambás, T H; França, J S; Callisto, M

    2011-08-01

    Dams are a major threat to aquatic biological diversity. By altering the natural flow of rivers, dams modify fluvial habitats, making them unsuitable for the growth and reproduction of many aquatic species. The aim of this study was to evaluate the effects of a reduced flow reach (RFR) on benthic macroinvertebrate communities. Benthic macroinvertebrates were collected at six sites downstream of the Amador Aguiar Power Plant I before (lotic phase) and after (semi-lentic phase) Araguari River mean flow was reduced from 346 to 7 m³.s⁻¹. Changes in macroinvertebrates richness, diversity and total biomass were not observed. Ablabesmyia, Tanytarsus (Chironomidae, Diptera), Leptoceridae and Polycentropodidae (Trichoptera) densities significantly increased the first year after flow reduction and the construction of spillways (t-test; p < 0.05). An analysis of similarity (ANOSIM) showed statistical differences in taxonomical composition despite considerable overlap in communities between the lotic and semi-lentic phases (R = 0.3; p < 0.01). In both phases, the macroinvertebrates were characterised by the dominance of groups tolerant to human disturbance (e.g., Chironomidae, Ceratopogonidae and Oligochaeta) and by the presence of the alien bivalve species Corbicula fluminea (Veneroidae), suggesting that the river was already degraded before the hydraulic modifications. Since the 1980s, the Araguari River has been continuously subjected to human pressures (e.g., cascade dams, urbanization and replacement of native vegetation by pasture and crops). These activities have led to impoverishment of biological communities and have consequently altered the ecosystem. PMID:21881787

  13. 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.

  14. 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.

  15. 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. PMID:21713480

  16. 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

  17. 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

  18. 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.

  19. Polycyclic aromatic hydrocarbons in bivalves from the San Francisco estuary: Spatial distributions, temporal trends, and sources (1993-2001).

    PubMed

    Oros, Daniel R; Ross, John R M

    2005-10-01

    Bivalve tissue samples were examined over a range of spatial and temporal scales (1993-2001) to determine PAH distributions, trends, and possible sources. Mussels (Mytilus californianus), oysters (Crassostrea gigas), and clams (Corbicula fluminea) were deployed for three months in the estuary at stations remote from known point source discharges. The range of summation operatorPAH detected in bivalves was oysters 184-6899 microg/kg dry wt (mean 678 microg/kg dry wt), mussels 21-1093 microg/kg dry wt (mean 175 microg/kg dry wt), and clams 78-720 microg/kg dry wt (mean 323 microg/kg dry wt). Linear regression analysis showed no statistically significant (p>0.05) temporal trends in clam and mussel summation operatorPAH at any of the deployment stations or estuary segments. On the other hand, a statistically significant (p<0.05) decreasing trend was found in summation operatorPAH in oysters at the Petaluma River station, and in the North Estuary segment. PAH isomer pair ratios applied as diagnostic indicators suggested that the bioaccumulated PAH were derived primarily from petroleum combustion, with lesser amounts derived from biomass and coal combustion, and unburned petroleum. PMID:15924995

  20. Toxicity of a traditional molluscicide to asian clam veligers

    USGS Publications Warehouse

    Layhee, Megan J.; Miho Yoshioka; Miho Yoshioka; Bahram Farokhkish; 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.

  1. 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.

  2. Residues of organochlorine insecticides, polychlorinated biphenyls, and heavy metals in biota from Apalachicola River, Florida, 1978.

    PubMed

    Winger, P V; Sieckman, C; May, T W; Johnson, W W

    1984-01-01

    Seventy-seven composite samples composed of largemouth bass ( Micropterus salmoides ), channel catfish ( Ictaluras punctatus), threadfin shad ( Dorosoma petenense ), Asiatic clam (Corbicula fluminea ), burrowing mayfly ( Hexagenia sp.), water snake ( Natrix spp.), and little green heron ( Butorides virescens ) were collected from upper and lower reaches of the Apalachicola River, Florida, in 1978 for residue analysis of organochlorine insecticides, PCBs (polychlorinated biphenyls), and metals. Compared with data from the National Pesticide Monitoring Program and criteria recommended for the protection of aquatic life, residue concentrations were moderately high in the Apalachicola River. Biota from the upper river generally had higher organic and lower metal residues than those from the lower river. Highest residues in the biota were total DDT, total PCBs, and toxaphene. Although individual mean concentrations were below 2 micrograms/g and total organic contaminant residues never exceeded 5 micrograms/g, residue concentrations of DDT, PCBs, and toxaphene (particularly from the upper river) exceeded recommended permissible levels for the protection of aquatic life. Metal residues were generally below 1 microgram/g. Exceptions were arsenic residues in threadfin shad (1.07 micrograms/g) and Asiatic clams (1.75 micrograms/g), and selenium in eggs of channel catfish (1.39 micrograms/g). The residues observed in the biota, particularly from the upper station, indicated moderate contamination of the Apalachicola River system at the time samples were collected. PMID:6427177

  3. Family Structure and Social Influence.

    ERIC Educational Resources Information Center

    Olson, Dawn R.

    Regardless of family form, there is a universal belief that one's family is the most powerful agent of socialization. A sample of 38 junior high school students from single parent and nuclear families completed a questionnaire in order to examine the relative effects of peer influence and family influence in single parent and nuclear families.…

  4. 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…

  5. 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...

  6. 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…

  7. 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)

  8. Conceptual Dimensions of Interpersonal Influence.

    ERIC Educational Resources Information Center

    McCallum, Debra Moehle; And Others

    Interpersonal power has been defined as the ability of an agent to alter the behavior of a target through means-control, attractiveness, and credibility. To identify and delineate situations of influence in personal relationships, undergraduate students either wrote influence descriptions (N=96), made similarity judgments on the original 96…

  9. 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)

  10. Influence of Mercury

    NASA Astrophysics Data System (ADS)

    Tackley, P. J.; Aurnou, J. M.; Aubert, J.

    2009-04-01

    Due to the absence of an atmosphere and proximity to the Sun, Mercury's surface temperature varies laterally by several 100s K, even when averaged over long time periods. The dominant variation in time-averaged surface T occurs from pole to equator (~225 K) [1]. The resonant relationship between Mercury's orbit and rotation results in a smaller longitudinal variation (~100 K) [1]. Here we demonstrate, using models of mantle convection in a 3-D spherical shell, that this stationary lateral variation in surface temperature has a small but significant influence on mantle convection and on the lateral variation of heat flux across the core-mantle boundary (CMB). We evaluate the possible observational signature of this laterally-varying convection in terms of boundary topography, stress distribution, gravity and moment of inertia tensor. We furthermore test whether the lateral variation in CMB flux is capable of driving a thermal wind dynamo, i.e., weak dynamo action with no internally-driven core convective motions. For Mercury's mantle we assume a dry olivine rheology including both diffusion creep and disclocation creep with rheological parameters such as activation energy and volume taken from the synthesis of [2]. We assume decaying radiogenic heat sources with the same concentration as in the bulk silicate Earth, and a parameterised model of core cooling. The models are run for 4.5 Ga from a relatively hot initial state with random initial perturbations. We use the code StagYY, which uses a finite-volume discretization on a spherical yin-yang grid and a multigrid solver [3]. Results in spherical axisymmetric geometry, compare a case with constant surface temperature to one with a latitude-dependent surface temperature. The system forms about 3 convection cells from pole to equator. Although the results look similar to first order, in the latitude-dependent case the convection is noticably more sluggish and colder towards the pole. In CMB flux, both cases display

  11. 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. PMID:26582997

  12. 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.

  13. 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

  14. 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. PMID:27540501

  15. 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

  16. 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…

  17. 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/).

  18. 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…

  19. Factors influencing dental decision making.

    PubMed

    Grembowski, D; Milgrom, P; Fiset, L

    1988-01-01

    In clinical decision making, dentists routinely choose between alternative treatments such as crown vs amalgam/composite buildup, root canal vs extraction, fixed bridge vs removable partial denture, and prophylaxis vs subgingival curettage or periodontal scaling. A number of technical and patient factors can influence dentists' choice of treatment in these situations; however, little is known about their relative importance. To address this issue, a list of technical (e.g., periodontal status and caries rate) and patient (e.g., cost and patient preference) factors possibly influencing choice of treatment was developed for each pair of services. Responding to a mail questionnaire, 156 general dentists in Washington State listed the top three factors influencing their choice of service in each pair. Results revealed that dentists took different factors into account in choosing among alternative treatments. Technical factors dominated over patient concerns; only about 33 percent of the dentists considered patient factors important in choosing alternative therapies. The latter group was less preventively oriented, were solo practitioners, worked longer hours, and had lower prices. Results suggest patients may have little influence on prescriptions of therapy among experienced general dentists. PMID:3045303

  20. 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.…

  1. FORCES INFLUENCING THE COUNSELOR'S ROLE.

    ERIC Educational Resources Information Center

    MOLER, DONALD

    DEFINING THE ROLE OF A COUNSELOR IS A TASK WHICH IS COMPLICATED BY THE CHANGING WORLD, THE CHANGING SOCIAL STRUCTURE, AND THE INFLUENCES OF GOVERNMENT. THE ROLE IS FURTHER COMPLICATED BY THE FACT THAT COUNSELING HAS ORIGINATED FROM A VARIETY OF DISCIPLINES, BORROWING FROM THE JOB OF THE TEACHER, THE ADMINISTRATOR, THE SOCIAL WORKER, AND THE…

  2. 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 throughout the…

  3. Gender Influences in Classroom Interaction.

    ERIC Educational Resources Information Center

    Wilkinson, Louise Cherry, Ed.; Marrett, Cora B., Ed.

    The 11 chapters comprising this work focus on the interactional influences that may be related to differential classroom experiences for males and females. The effects of contextual factors, teacher characteristics, and student characteristics are investigated. Addressed primarily to researchers, this information should prove useful to teachers,…

  4. 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.

  5. 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 Study," a…

  6. Community Influences on Cognitive Ability.

    ERIC Educational Resources Information Center

    Coon, Hilary; And Others

    1992-01-01

    Associations between community environment and cognitive ability were studied in 167 adoptive and 175 nonadoptive Colorado families. Seven families were omitted. A proposed model, tested by census measures, finds several aspects of communities showing environmental relationships with child IQ over parental influences. Rural communities have a…

  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. Attractiveness and Influence in Counseling

    ERIC Educational Resources Information Center

    Schmidt, Lyle D.; Strong, Stanley R.

    1971-01-01

    The results showed that in spite of violently different feelings about (or descriptions of) the roles, the subjects were equally influenced by them. This suggests that social attractiveness may not be important when the client's problems require expert opinion and knowledge. (Author/CG(

  10. Physical Attractiveness and Interpersonal Influence

    ERIC Educational Resources Information Center

    Dion, Karen K.; Stein, Steven

    1978-01-01

    Examines the hypothesis that attractive individuals should be more successful with opposite-sex peers but less successful with same-sex peers than unattractive individuals. Also investigates the influence strategies employed by persons differing in attractiveness since nothing is currently known about the actual behavior exhibited by attractive…

  11. 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…

  12. 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 and the…

  13. The Influences of Rudolf Laban.

    ERIC Educational Resources Information Center

    Foster, John

    Rudolf Laban has influenced the introduction and development of modern educational dance as well as general education. Much of the available material concerning Laban is arts oriented; it is concerned with dance as an art form and is not focused towards the educational uses of Laban's ideas. This volume attempts to present materials relevant to…

  14. Genetic factors influencing alcohol dependence

    PubMed Central

    Mayfield, R D; Harris, R A; Schuckit, M A

    2008-01-01

    Plentiful data from both animal and human studies support the importance of genetic influences in substance abuse and dependence (Bierut et al., 1998; Tsuang et al., 1998; Kendler et al., 2003). This review summarizes the evidence supporting such genetic influences, places them into perspective regarding animal and human studies, discusses the importance of both genes and environment, and highlights some specific genes of interest regarding the vulnerabilities for problems associated with alcohol use disorders. A long history of repetitive heavy use of alcohol exists across generations as well as the high prevalence of alcohol-related problems in Western societies. Moreover, the information offered here addresses the importance of more general issues regarding genetics and gene expression related to alcohol abuse and dependence. PMID:18362899

  15. Vestibular influence on tongue activity.

    PubMed

    Elmund, J; Bowman, J P; Morgan, R J

    1983-07-01

    The vestibular system was electrically stimulated in cats anesthetized with ketamine. Peripheral stimulation by an electrode positioned in the vestibule evoked torsional contralateral eye deviations and an electromyogram (EMG) response in a contralateral dorsal neck extensor. Consistently associated with this well documented vestibular pattern was an EMG response in tongue protrusive muscles, at a latency of 13 +/- 5 (means +/- SD) ms. Stimulation in a specific part of the rostroventral lateral vestibular nucleus elicited the same combination of responses: torsional contralateral eye deviations, dorsal neck EMG, and tongue EMG at a latency of 14 +/- 3 ms. Possible tongue activation by current spread to peripheral and central neural structures was examined in detail. Cerebellar, V, VII, cochlear, IX, X, and XII nerve influences were considered. On the basis of combined evidence, it was concluded that the vestibular system does influence tongue activity. PMID:6602714

  16. Genetic influences on brain structure.

    PubMed

    Thompson, P M; Cannon, T D; Narr, K L; van Erp, T; Poutanen, V P; Huttunen, M; Lönnqvist, J; Standertskjöld-Nordenstam, C G; Kaprio, J; Khaledy, M; Dail, R; Zoumalan, C I; Toga, A W

    2001-12-01

    Here we report on detailed three-dimensional maps revealing how brain structure is influenced by individual genetic differences. A genetic continuum was detected in which brain structure was increasingly similar in subjects with increasing genetic affinity. Genetic factors significantly influenced cortical structure in Broca's and Wernicke's language areas, as well as frontal brain regions (r2(MZ) > 0.8, p < 0.05). Preliminary correlations were performed suggesting that frontal gray matter differences may be linked to Spearman's g, which measures successful test performance across multiple cognitive domains (p < 0.05). These genetic brain maps reveal how genes determine individual differences, and may shed light on the heritability of cognitive and linguistic skills, as well as genetic liability for diseases that affect the human cortex. PMID:11694885

  17. 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

  18. Influence of confinement on thermodiffusion

    NASA Astrophysics Data System (ADS)

    Hannaoui, Rachid; Galliero, Guillaume; Hoang, Hai; Boned, Christian

    2013-09-01

    This work focuses on a possible influence of a nanoporous medium on the thermodiffusion of a fluid "isotopic" mixture. To do so, we performed molecular dynamics simulations of confined Lennard-Jones binary equimolar mixtures using grand-canonical like and non-equilibrium approaches in sub- and super-critical conditions. The study was conducted in atomistic slit pore of three adsorbent natures for various widths (from 5 to 35 times the size of a molecule). The simulation results indicate that for all thermodynamic conditions and whatever the pore characteristics, the confinement has a negligible effect on the thermal diffusion factor/Soret coefficient. However, when considered separately, the mass diffusion and thermodiffusion coefficients have been found to be largely influenced by the pore characteristics. These two coefficients decrease noticeably when adsorption is stronger and pore width smaller, a behavior that is consistent with a simple hydrodynamic explanation.

  19. 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

  20. 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. PMID:21289535

  1. 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.

  2. 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

  3. 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.

  4. "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.

  5. 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.)

  6. 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…

  7. Circadian influences on myocardial infarction.

    PubMed

    Virag, Jitka A I; Lust, Robert M

    2014-01-01

    Components of circadian rhythm maintenance, or "clock genes," are endogenous entrainable oscillations of about 24 h that regulate biological processes and are found in the suprachaismatic nucleus (SCN) and many peripheral tissues, including the heart. They are influenced by external cues, or Zeitgebers, such as light and heat, and can influence such diverse phenomena as cytokine expression immune cells, metabolic activity of cardiac myocytes, and vasodilator regulation by vascular endothelial cells. While it is known that the central master clock in the SCN synchronizes peripheral physiologic rhythms, the mechanisms by which the information is transmitted are complex and may include hormonal, metabolic, and neuronal inputs. Whether circadian patterns are causally related to the observed periodicity of events, or whether they are simply epi-phenomena is not well established, but a few studies suggest that the circadian effects likely are real in their impact on myocardial infarct incidence. Cycle disturbances may be harbingers of predisposition and subsequent response to acute and chronic cardiac injury, and identifying the complex interactions of circadian rhythms and myocardial infarction may provide insights into possible preventative and therapeutic strategies for susceptible populations. PMID:25400588

  8. 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. PMID:20610173

  9. 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.

  10. Circadian influences on myocardial infarction

    PubMed Central

    Virag, Jitka A. I.; Lust, Robert M.

    2014-01-01

    Components of circadian rhythm maintenance, or “clock genes,” are endogenous entrainable oscillations of about 24 h that regulate biological processes and are found in the suprachaismatic nucleus (SCN) and many peripheral tissues, including the heart. They are influenced by external cues, or Zeitgebers, such as light and heat, and can influence such diverse phenomena as cytokine expression immune cells, metabolic activity of cardiac myocytes, and vasodilator regulation by vascular endothelial cells. While it is known that the central master clock in the SCN synchronizes peripheral physiologic rhythms, the mechanisms by which the information is transmitted are complex and may include hormonal, metabolic, and neuronal inputs. Whether circadian patterns are causally related to the observed periodicity of events, or whether they are simply epi-phenomena is not well established, but a few studies suggest that the circadian effects likely are real in their impact on myocardial infarct incidence. Cycle disturbances may be harbingers of predisposition and subsequent response to acute and chronic cardiac injury, and identifying the complex interactions of circadian rhythms and myocardial infarction may provide insights into possible preventative and therapeutic strategies for susceptible populations. PMID:25400588

  11. [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. PMID:18624229

  12. Predator identity influences metacommunity assembly.

    PubMed

    Johnston, Nicole K; Pu, Zhichao; Jiang, Lin

    2016-09-01

    Predation is among the most important biotic factors influencing natural communities, yet we have a rather rudimentary understanding of its role in modulating metacommunity assembly. We experimentally examined the effects of two different predators (a generalist and a specialist) on metacommunity assembly, using protist microcosm metacommunities that varied in predator identity, dispersal among local communities and the history of species colonization into local communities. Generalist predation resulted in reduced α diversity and increased β diversity irrespective of dispersal, likely due to predation-induced stochastic extinction of different prey species in different local communities. Dispersal, however, induced source-sink dynamics in the presence of specialist predators, resulting in higher α diversity and marginally lower β diversity. These results demonstrate the distinct effects of different predators on prey metacommunity assembly, emphasizing the need to explore the role of predator diet breadth in structuring metacommunities. PMID:27349796

  13. 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.

  14. 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. PMID:25749702

  15. Human diffusion and city influence.

    PubMed

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

    2015-08-01

    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

  16. 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

  17. Plasma Influence on Tungsten Powder

    NASA Astrophysics Data System (ADS)

    Zakharov, A.; Begrambekova, S.; Grunin, A.

    Modifications of tungsten powder comprised of micro particles with dimensions: 1 ± 0.2 μm and 5 ± 1.5 μm ("small" and «large" particles) under the influence of heating, electric field and hydrogen- and argon ion irradiation are investigated in this work. The processes in irradiated powder are described and discussed. Among them there are powder outgassing, particle emission from the powder surface in the electric field, pasting of small particles all over the large ones, integration of the adhered small particles and formation of the uniform layer around the groups of large particles, cone growth on uniform layers, formation of volumetric chains of sticking together tungsten particles and their transformations. Driving forces and processes providing different types of powder modifications and the role of each of them in the specific phenomena are discussed.

  18. Target animacy influences gorilla handedness.

    PubMed

    Forrester, Gillian S; Leavens, David A; Quaresmini, Caterina; Vallortigara, Giorgio

    2011-11-01

    We investigated the unimanual actions of a biological family group of twelve western lowland gorillas (Gorilla gorilla gorilla) using a methodological approach designed to assess behavior within social context from a bottom-up perspective. Measures of both the lateralization of unimanual actions (left, right) and the target of the action (animate, inanimate) were assessed during dual, synchronized video observations of naturalistic behavior. This paper demonstrates a corelationship between handedness and the animate quality of the target object. Analyses demonstrated a significant interaction between lateralized unimanual actions and target animacy and a right-hand bias for actions directed toward inanimate targets. We suggest that lateralized motor preference reflects the different processing capabilities of the left and right hemispheres, as influenced by the emotive (animate) and/or functional (inanimate) characteristics of the target, respectively. PMID:21562817

  19. Environmental Influences on Genomic Imprinting

    PubMed Central

    Kappil, Maya; Lambertini, Luca; Chen, Jia

    2015-01-01

    Genomic imprinting refers to the epigenetic mechanism that results in the mono-allelic expression of a subset of genes in a parent-of-origin manner. These haploid genes are highly active in the placenta and are functionally implicated in the appropriate development of the fetus. Furthermore, the epigenetic marks regulating imprinted expression patterns are established early in development. These characteristics make genomic imprinting a potentially useful biomarker for environmental insults, especially during the in utero or early development stages, and for health outcomes later in life. Herein, we critically review the current literature regarding environmental influences on imprinted genes and summarize findings that suggest that imprinted loci are sensitive to known teratogenic agents, such as alcohol and tobacco, as well as less established factors with the potential to manipulate the in utero environment, including assisted reproductive technology. Finally, we discuss the potential of genomic imprinting to serve as an environmental sensor during early development. PMID:26029493

  20. 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. PMID:26203050

  1. 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.

  2. Trends in the Genetic Influences on Smoking

    PubMed Central

    Boardman, Jason D.; Blalock, Casey L.; Pampel, Fred C.

    2011-01-01

    Using twin pairs from the National Survey of Midlife Development in the United States, we estimate that 35 percent of the variance in regular smoking is due to additive genetic influences. When we disaggregate the sample by birth cohort we witness strong genetic influences on smoking for those born in the 1920s, 1930s, and 1950s, but negligible influences for those born in the 1940s and 1960s. We show that the timing of the first Surgeon General’s Report coincides with an increase in the genetic influences on regular smoking, but subsequent legislation prohibiting smoking in public places has significantly reduced these influences. These results are in line with existing gene-environment interaction theory, and we argue that variation in genetic influences across cohorts makes it difficult and potentially misleading to estimate genetic effects on health behaviors from data obtained from a single point in time. PMID:20420298

  3. Factors influencing boar sperm cryosurvival.

    PubMed

    Roca, J; Hernández, M; Carvajal, G; Vázquez, J M; Martínez, E A

    2006-10-01

    Optimal sperm cryopreservation is a prerequisite for the sustainable commercial application of frozen-thawed boar semen for AI. Three experiments were performed to identify factors influencing variability of postthaw sperm survival among 464 boar ejaculates. Sperm-rich ejaculate fractions were cryopre-served using a standard freezing-thawing procedure for 0.5-mL plastic straws and computer-controlled freezing equipment. Postthaw sperm motility (assessed with a computer-assisted semen analysis system) and viability (simultaneously probed by flow cytometry analysis after triple-fluorescent stain), evaluated 30 and 150 min postthaw, were used to estimate the success of cryopreservation. In the first experiment, 168 unselected ejaculates (1 ejaculate/boar), from boars of 6 breeds with a wide age range (8 to 48 mo), were cryopreserved over a 12-mo period to evaluate the predictive value of boar (breed and age), semen collection, transport variables (season of ejaculate collection, interval between collections, and ejaculate temperature exposure), initial semen traits, and sperm quality before freezing on sperm survival after freezing-thawing. In Exp. 2, 4 ejaculates from each of 29 boars, preselected according to their initial semen traits and sperm quality before freezing, were collected and frozen over a 6-mo period to evaluate the influence of interboar and intraboar ejaculate variability in the survival of sperm after cryopreservation. In Exp. 3, 12 ejaculates preselected as for Exp. 2, from each of 15 boars with known good sperm cryosurvival, were collected and frozen over a 12-mo period to estimate the sustainability of sperm cryosurvival between ejaculates over time. Boar and semen collection and transport variables were not predictive of sperm cryosurvival among ejaculates. Initial semen traits and sperm quality variables observed before freezing explained 23.2 and 10.9%, respectively, of the variation in postthaw sperm motility and viability. However, more that

  4. [Endocrine factors influencing melanoma progression].

    PubMed

    Dobos, Judit

    2009-03-01

    According to recent findings that beside cancers traditionally considered as hormone-dependent, several other tumor types show different behavior in the two sexes, indicating the possible role of endocrine factors in the course of these diseases. The possibility that endocrine factors may influence the clinical course of human malignant melanoma is suggested by the higher survival rate in premenopausal vs. postmenopausal women or men of any ages. However, investigations on the sex hormone receptor status of human cutaneous melanomas and experiments attempting to support the epidemiological results yielded conflicting results. In our human melanoma cell lines we failed to detect steroid receptors at protein level, while quantitative PCR demonstrated that their mRNA expression level was orders of magnitude lower compared to the positive control cell lines. Sex hormones did not influence the in vitro features of the human melanoma cells considerably. On the other hand, glucocorticoid receptor was present both at mRNA and protein level, although dexamethasone was effective in vitro only at high doses. Our previous experiments showed that intrasplenic injection of human melanoma cells resulted in a significantly higher number of liver colonies in male than in female SCID mice. We now show that this difference evolves during the first day. After injection into the tail vein we did not observe gender-dependent difference in the efficiency of pulmonary colonization. Examining the pattern of metastasis formation after intracardiac injection, we have found differences between the two sexes in the incidence or number of colonies only in the case of the liver but not in other organs. We concluded that the observed phenomenon is specific to the liver; therefore we investigated the effects of 2-methoxyestradiol, an endogenous metabolite of estradiol produced mainly in the liver, with an estrogen receptor-independent antitumor activity. 2ME2 effectively inhibited melanoma cell

  5. Drift of dislocation tripoles under ultrasound influence.

    PubMed

    Murzaev, R T; Bachurin, D V; Nazarov, A A

    2016-01-01

    Numerical simulations of dynamics of different stable dislocation tripoles under influence of monochromatic standing sound wave were performed. The basic conditions necessary for the drift and mutual rearrangements between dislocation structures were investigated. The dependence of the drift velocity of the dislocation tripoles as a function of the frequency and amplitude of the external influence was obtained. The results of the work can be useful in analysis of motion and self-organization of dislocation structure under ultrasound influence. PMID:26278625

  6. Bioimpedance in medicine: Measuring hydration influence

    NASA Astrophysics Data System (ADS)

    Hlubik, J.; Hlubik, P.; Lhotska, L.

    2010-04-01

    The aim of the paper is to present results of our ongoing research focused on the influence of body hydration on the body impedance measurements and also on the influence of the frequency used for the measurement. The question is why to measure human body composition and if these values have beneficial results. First goal of the work deals with a question of measuring human body composition. The performed measurements showed certain influence which must be verified by repeated experiments.

  7. 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

  8. 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.

  9. Structural influences on intensity interferometry

    NASA Astrophysics Data System (ADS)

    Maji, Arup; Harris, Mark

    2016-01-01

    Intensity interferometry (II) is an alternate form of creating images of distant objects. It is significantly less sensitive to atmospheric distortions and aberrations of telescope surfaces than conventional amplitude-based imaging. The deficiencies of II can be overcome as photodetectors' read-out rates are becoming faster and computers more powerful. In recognition of the possibility of very large space-based imaging systems, this paper investigates how the deformation of a large, thin optical surface would influence the accuracy of II. Based on the theoretical foundation of II, an optical ray-tracing algorithm was used to examine how the statistics of a photon stream changes from the source to the detector. Ray-tracing and finite element analyses of the structure were thereafter integrated to quantify how the correlation of the intensity field changes as the reflective structure deforms. Varying the positions of the detector from the focal plane and the surface profile of the mirror provided an understanding and quantification of how the various scenarios affect the statistics of the detected light and the correlation measurement. This research and analysis provide the means to quantify how structural perturbations of focal mirrors affect the statistics of photon stream detections inherent in II instrumentation.

  10. The influence of matrix microstructure

    NASA Astrophysics Data System (ADS)

    Vyletel, G. M.; Allison, J. E.; Aken, D. C.

    1993-11-01

    The low-cycle and high-cycle fatigue behavior and cyclic response of naturally aged and artificially aged 2219/TiC/15p and unreinforced 2219 Al were investigated utilizing plastic strain-controlled and stress-controlled testing. The cyclic response of both the reinforced and un-reinforced materials was similar for all plastic strain amplitudes tested except that the saturation stress level for the composite was always greater than that of the unreinforced material. The cyclic response of the naturally aged materials exhibited cyclic hardening and, in some cases, cyclic softening, while the cyclic response for the artificially aged materials showed no evidence of either cyclic hardening or softening. The higher ductility of the unreinforced material made it more resistant to fatigue failure at high strains, and thus, at a given plastic strain, it had longer fatigue life. It should be noted that the tensile ductilities of the 2219/TiC/15p were significantly higher than those previously reported for 2XXX-series composites. During stress-controlled test-ing at stresses below 220 MPa, the presence of TiC particles lead to an improvement in fatigue life. Above 220 MPa, no influence of TiC reinforcement on fatigue life could be detected. In both the composite and unreinforced materials, the low-cycle and high-cycle fatigue lives were found to be virtually independent of matrix microstructure.

  11. 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.

  12. Can research influence clinical practice?

    PubMed

    Jiménez, Juan Pablo

    2007-06-01

    After briefly reviewing the unfavourable reception accorded empirical research by parts of the psychoanalytic community, as well as some of the benefits to clinical practice of analysts being involved in research activities, the author examines whether the findings of process and outcome research in psychotherapy and psychoanalysis can help identify the most appropriate forms of intervention for producing therapeutic change, given the specific condition of the patient and the relationship that the individual establishes with the analyst. He argues that research findings can influence clinical practice on various levels and in different areas, and goes on to examine a number of related issues: the specificity of therapeutic interventions versus the relevance of common curative factors; the dyadic conception of technique and ways of understanding the therapeutic action of the treatment alliance; and the strategic or heuristic conception in psychoanalytic therapy. Finally, the author presents clinical material with the aim of illustrating how the knowledge acquired through research can be applied to psychoanalytic treatment. PMID:17537698

  13. 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).

  14. Environmental factors influencing blackfly populations

    PubMed Central

    Carlsson, G.

    1967-01-01

    Much more information is required on the distribution of blackflies in various parts of the world, and in many cases an adequate methodology for obtaining such information still has to be worked out. A detailed methodology for the collection of information about blackflies is given, which was developed for investigations mainly in the Holarctic regions but is basically applicable to other parts of the world. A brief survey of the population dynamics of various species of blackflies in various parts of the Holarctic regions is given, and the main factors influencing the population dynamics are discussed. Interspecific and intraspecific fluctuations in natural blackfly populations are attributed chiefly to abiotic environmental factors rather than to competition. Larval competition in a given microhabitat is mainly individual, though specimens belonging to a given species may have a slightly more favourable position than others. The use of parasites and in particular the replacement of one species by another are promising methods of blackfly control. Predators are not generally likely to prove useful for this purpose. PMID:5300046

  15. 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.

  16. 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

  17. 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.

  18. Situating social influence processes: dynamic, multidirectional flows of influence within social networks.

    PubMed

    Mason, Winter A; Conrey, Frederica R; Smith, Eliot R

    2007-08-01

    Social psychologists have studied the psychological processes involved in persuasion, conformity, and other forms of social influence, but they have rarely modeled the ways influence processes play out when multiple sources and multiple targets of influence interact over time. However, workers in other fields from sociology and economics to cognitive science and physics have recognized the importance of social influence and have developed models of influence flow in populations and groups-generally without relying on detailed social psychological findings. This article reviews models of social influence from a number of fields, categorizing them using four conceptual dimensions to delineate the universe of possible models. The goal is to encourage interdisciplinary collaborations to build models that incorporate the detailed, microlevel understanding of influence processes derived from focused laboratory studies but contextualized in ways that recognize how multidirectional, dynamic influences are situated in people's social networks and relationships. PMID:18453465

  19. Environmental Influences on Hurricane Intensification

    NASA Astrophysics Data System (ADS)

    Merrill, Robert T.

    Though qualitatively similar in structure, different hurricanes can attain different peak intensities during their lifetimes. Forecasters and empiricists relate the intensity to the sea surface temperature and the "effectiveness" of the upper tropospheric outflow, but offer no clear explanation of how the latter operates. Numerical modelers usually ignore the surrounding flow and emphasize interaction between the convective and vortex scales exclusively. This dissertation examines more closely the observed upper-tropospheric environmental flow differences between hurricanes which intensify and those which fail to do so, and combines them with previously published empirical and modeling results into a general conceptual model of environmental influences on hurricane intensification. Upper tropospheric wind observations (from satellite cloud tracking, aircraft reports, and rawinsondes) are composited for 28 hurricanes according to intensity tendency. A rotated coordinate system based on the outflow jet location is used so that the asymmetric flow structure is preserved. Little difference is observed in total outflow on the synoptic scale. However, intensifying hurricanes have a less constricted outflow with evidence of lateral connections with the surrounding flow. The asymmetric flow consists of a wave thought to be associated with barotropic instability of the anticyclonic flow above the hurricane and the juxtaposition of surrounding flow features. A quasi-equilibrium balance between hurricane convection and the upper tropospheric environment is proposed. The moist-neutral stratification of the vortex core is a balance between the convection which acts to increase stability and the outflow which acts to reduce it. Reduce the outflow layer cooling and the core stabilizes convective buoyancy is reduced, and a new balance with less vigorous convection is established. If vertically sheared, the environmental flow can also regulate intensity by inducing asymmetric

  20. Influence of antidepressants on hemostasis.

    PubMed

    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. PMID

  1. Fermionic influence on inflationary fluctuations

    NASA Astrophysics Data System (ADS)

    Boyanovsky, Daniel

    2016-04-01

    Motivated by apparent persistent large scale anomalies in the cosmic microwave background we study the influence of fermionic degrees of freedom on the dynamics of inflaton fluctuations as a possible source of violations of (nearly) scale invariance on cosmological scales. We obtain the nonequilibrium effective action of an inflaton-like scalar field with Yukawa interactions (YD ,M) to light fermionic degrees of freedom both for Dirac and Majorana fields in de Sitter space-time. The effective action leads to Langevin equations of motion for the fluctuations of the inflaton-like field, with self-energy corrections and a stochastic Gaussian noise. We solve the Langevin equation in the super-Hubble limit implementing a dynamical renormalization group resummation. For a nearly massless inflaton its power spectrum of super-Hubble fluctuations is enhanced, P (k ;η )=(H/2 π )2eγt[-k η ] with γt[-k η ]=1/6 π2 [∑i =1 NDYi,D 2+2 ∑j =1 NMYj,M 2]{ln2[-k η ]-2 ln [-k η ]ln [-k η0]} for ND Dirac and NM Majorana fermions, and η0 is the renormalization scale at which the inflaton mass vanishes. The full power spectrum is shown to be renormalization group invariant. These corrections to the super-Hubble power spectrum entail a violation of scale invariance as a consequence of the coupling to the fermionic fields. The effective action is argued to be exact in the limit of a large number of fermionic fields. A cancellation between the enhancement from fermionic degrees of freedom and suppression from light scalar degrees of freedom conformally coupled to gravity suggests the possibility of a finely tuned supersymmetry among these fields.

  2. 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…

  3. 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…

  4. Explaining Sibling Similarities: Perceptions of Sibling Influences

    ERIC Educational Resources Information Center

    Whiteman, Shawn D.; McHale, Susan M.; Crouter, Ann C.

    2007-01-01

    This study examined older siblings' influence on their younger brothers and sisters by assessing the connections between youth's perceptions of sibling influence and sibling similarities in four domains: Risky behavior, peer competence, sports interests, and art interests. Participants included two adolescent-age siblings (firstborn age M=17.34;…

  5. 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

  6. Parental Influence and Involvement on Reading Achievement.

    ERIC Educational Resources Information Center

    Nebor, Jon N.

    A review of the research on the effects of parental influence and parental involvement on children's reading achievement indicates that when parents take an active and positive part in their child's education the results often turn out well for the student. Parental influence is defined as any opinion, attitude, or action (other than direct…

  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 Momentary Goal Structures

    ERIC Educational Resources Information Center

    Zaleski, Diana Janet

    2010-01-01

    Adolescents' cognition is influenced by a dynamic educational environment. Studies examining the influence of schools, classrooms, and teachers often overlook the momentary variation found in these environments and the effect this variation has on student cognition. Using an achievement goal theory framework, this study examined the momentary…

  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. Influencing State Policy: Information, Access and Timing

    ERIC Educational Resources Information Center

    Jackson-Elmoore, Cynthia

    2006-01-01

    Increasingly, public health promotion is about more than influencing individual behavior. Rather, it is equally important to undertake efforts to impact social, environmental, and political factors. Having a clear understanding of the inner workings of the legislative process enhances one's ability to effectively influence policy. It is important…

  11. Influence: The Organizer in Communication Systems

    ERIC Educational Resources Information Center

    Browning, Larry; And Others

    1976-01-01

    This paper outlines an array of categories that denote kinds of influence variables operative in organizational systems--including structures, relationships, and technology. This allows us to synthesize literature from a variety of system levels and sources by addressing the question: What variables influence a communicator's behavior at any given…

  12. 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…

  13. 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…

  14. The Influence of Culture on Teacher Commitment

    ERIC Educational Resources Information Center

    Abd Razak, Nordin; Darmawan, I. Gusti Ngurah; Keeves, John P.

    2010-01-01

    Culture is believed to be an important factor that influences various aspects of human life, such as behaviour, thinking, perceptions and attitudes. This article examines the similarities and differences in the influence of culture on teacher commitment in three types of Malaysian primary schools. Since commitment to teaching has rarely been…

  15. 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…

  16. 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…

  17. 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. PMID:26207791

  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. Do Reading Habits Influence Aesthetic Preferences?

    ERIC Educational Resources Information Center

    Treiman, Rebecca; Allaith, Zainab

    2013-01-01

    We tested the idea that the directionality of a person's primary writing system has influences outside the domain of reading and writing, specifically influences on aesthetic preferences. The results of several previous studies suggest that people whose primary writing system goes from left to right prefer pictures of moving and static…

  20. 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.

  1. 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

  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. The Influence of Confucian Philosophy on Adult Learners Who Come from Confucian- Influenced Societies

    ERIC Educational Resources Information Center

    Chuang, Szu-Fang

    2007-01-01

    This paper reviews the literature on Confucian philosophy in general and explores its influences on adult learners who come from Confucian-influenced societies. The Confucian philosophy is reviewed to four principles and found to have a strong influence on Confucian adults in learning. The implication of findings and recommendations are discussed.…

  4. 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. PMID:20821462

  5. 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

  6. 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.

  7. 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.

  8. Diagnostic genetic markers and evolutionary relationships among invasive dreissenoid and corbiculoid bivalves in North America: phylogenetic signal from mitochondrial 16S rDNA.

    PubMed

    Stepien, C A; Hubers, A N; Skidmore, J L

    1999-10-01

    Diagnostic genetic markers from 486 aligned nucleotide sequences of mitochondrial 16S ribosomal DNA were developed for the four closely related species of dreissenoid and corbiculoid bivalves that have invaded North America; the zebra mussel Dreissena polymorpha, the quagga mussel D. bugensis, and the dark false mussel Mytilopsis leucophaeata of the superfamily Dreissenoidea, and the Asian clam Corbicula fluminea of the sister superfamily Corbiculoidea. Evolutionary relationships were examined among the four genera and comparisons were made with native Eurasian populations of D. polymorpha and D. bugensis. Tests were conducted for gender-specific mitochondrial lineages, which occur in some other bivalves. Genetic variability and divergence rates were tested between stem (paired) and loop (unpaired) regions of secondary structure. There were 251 variable nucleotide sites, of which 99 were phylogenetically informative. Overall transition to transversion ratio was 0.76:1.00 and both accumulated linearly in stem and loop regions, suggesting appropriate phylogenetic signal. Genetic distance calibration with the fossil record estimated the pairwise sequence divergence as 0. 0057 +/- 0.0004 per million years. Mytilopsis and Dreissena appear to have diverged about 20.7 +/- 2.7 million years ago. D. bugensis and D. polymorpha appear separated by about 13.2 +/- 2.2 million years. No intraspecific variation was found, including between Eurasian and North American populations, among shallow and deep morphotypes of D. bugensis and between the sexes. Restriction endonuclease markers were developed to distinguish among the species at all life history stages, allowing rapid identification in areas of sympatric distribution. PMID:10508537

  9. Comparing laboratory- and field-measured biota-sediment accumulation factors.

    PubMed

    Burkhard, Lawrence P; Arnot, Jon A; Embry, Michelle R; Farley, Kevin J; Hoke, Robert A; Kitano, Masaru; Leslie, Heather A; Lotufo, Guilherme R; Parkerton, Thomas F; Sappington, Keith G; Tomy, Gregg T; Woodburn, Kent B

    2012-01-01

    Standardized laboratory protocols for measuring the accumulation of chemicals from sediments are used in assessing new and existing chemicals, evaluating navigational dredging materials, and establishing site-specific biota-sediment accumulation factors (BSAFs) for contaminated sediment sites. The BSAFs resulting from the testing protocols provide insight into the behavior and risks associated with individual chemicals. In addition to laboratory measurement, BSAFs can also be calculated from field data, including samples from studies using in situ exposure chambers and caging studies. The objective of this report is to compare and evaluate paired laboratory and field measurement of BSAFs and to evaluate the extent of their agreement. The peer-reviewed literature was searched for studies that conducted laboratory and field measurements of chemical bioaccumulation using the same or taxonomically related organisms. In addition, numerous Superfund and contaminated sediment site study reports were examined for relevant data. A limited number of studies were identified with paired laboratory and field measurements of BSAFs. BSAF comparisons were made between field-collected oligochaetes and the laboratory test organism Lumbriculus variegatus and field-collected bivalves and the laboratory test organisms Macoma nasuta and Corbicula fluminea. Our analysis suggests that laboratory BSAFs for the oligochaete L. variegatus are typically within a factor of 2 of the BSAFs for field-collected oligochaetes. Bivalve study results also suggest that laboratory BSAFs can provide reasonable estimates of field BSAF values if certain precautions are taken, such as ensuring that steady-state values are compared and that extrapolation among bivalve species is conducted with caution. PMID:21538837

  10. 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.

  11. 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. PMID:27381875

  12. 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. PMID:27472029

  13. 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

  14. 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. PMID:26018906

  15. Factors influencing wetland use by Canada geese

    USGS Publications Warehouse

    Naugle, D.E.; Gleason, J.S.; Jenks, J.A.; Higgins, K.F.; Mammenga, P.W.; Nusser, S.M.

    1997-01-01

    Seasonal and semi-permanent wetlands in eastern South Dakota were surveyed in 1995 and 1996 to identify habitat characteristics influencing wetland use by Canada geese (Branta canadensis maxima). Position of a wetland within the landscape and its area were important landscape-scale features influencing wetland use by geese. Our delineation of potential Canada goose habitat using a wetland geographic information system indicated that distribution and area of semi-permanent wetlands likely limit Canada goose occurrence in regions outside the Prairie Coteau. Periodicity in hydrologic cycles within landscapes also may influence goose use of wetlands in eastern South Dakota.

  16. 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)

  17. Region effects influence local tree species diversity

    PubMed Central

    Ricklefs, Robert E.; He, Fangliang

    2016-01-01

    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. PMID:26733680

  18. 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. PMID:26733680

  19. 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 ...

  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. Latina mothers' influences on child appetite regulation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  2. 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

  3. Squirt flow influence on sonic log parameters

    NASA Astrophysics Data System (ADS)

    Markova, I.; Ronquillo Jarillo, G.; Markov, M.; Gurevich, B.

    2014-02-01

    Most sedimentary rocks contain movable fluid in the pores. Hydrodynamic effects due to wave-induced oscillatory fluid flow can lead to significant changes of velocities and attenuations of elastic waves in these rocks. In this paper, we consider the influence of a squirt flow (local flow between the pores of different compressibility) on the sonic log response. The calculations are performed using a unified model describing the joint influence of squirt flow and Biot's global flow. The results show that the influence of the squirt flow increases with increase of a signal frequency. This influence is relatively small in the case of the Stoneley wave but it is significant in the case of P and S waves.

  4. [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. PMID:24502184

  5. Simulated Convectively Influenced vs. Lightning Influenced Air: Methods for Calculation and Associated Uncertainties

    NASA Astrophysics Data System (ADS)

    Heath, N.; Freeman, S.; Fuelberg, H. E.

    2014-12-01

    Some atmospheric chemical processes are influenced by the presence of convection and/or lightning. Therefore, it is often important to determine whether a sampled air parcel previously has encountered these influences. This paper describes procedures for making these determinations and provides uncertainties associated with the procedures. Prior locations of the sampled air are obtained by calculating backward trajectories based on 1 h WRF output with 3 domains (horizontal grid spacing of 36, 12, and 4 km). Back trajectories are released along every DC-8 flight track from the recent NASA SEAC4RS campaign (~22,000 trajectories total). If lightning influence is sought, locations of the flashes usually are obtained from ground-based networks such as the National Lightning Detection Network (NLDN). Results show that the user-defined spatial and temporal separation between a trajectory and the flash location greatly influences whether the trajectory is considered lightning influenced. For example, a spatial threshold of 0.5 (0.25) deg lat/lon leads to 69% (60%) of the trajectories being lightning influenced. If model-derived convective influence is sought, a vertical displacement threshold corresponding to w≥1 m s-1 is used to identify convectively influenced parcels. Remarkably, the model-derived method using the 4 km WRF output leads to only 5% (compared to ~60% from lightning) of the trajectories being convectively influenced. Additionally, the horizontal grid spacing (36 km vs. 4 km) exerts a major influence on the paths of the trajectories. The overriding conclusion is that very different results are obtained depending on whether simulated convectively influenced or lightning influenced air is being sought. Also, once this choice is made, the resolution of the model and the time/space thresholds that are chosen will have a major impact on the number of trajectories that are determined to be influenced. This paper will provide guidance on these choices.

  6. [Gastrointestinal motility and possibilities of influencing it].

    PubMed

    Duris, I; Payer, J; Huorka, M; Randus, V; Ondrejka, P

    1994-06-01

    The authors discuss factors which influence the motility of the smooth muscles in the pancreatobiliary region. They investigated some clinical and laboratory parameters after administration of the selective antagonist of calcium influx-Pineverium bromide-Dicetel. The drug influenced significantly in a positive way nausea, flatulence, pain and chronically elevated amylases. The authors mention a cycle of possible neurohumoral changes with which specific calcium channel antagonists could interfere. PMID:8073641

  7. [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. PMID:8137381

  8. 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.

  9. Cooperative networks overcoming defectors by social influence

    NASA Astrophysics Data System (ADS)

    Gomez Portillo, Ignacio

    2014-01-01

    We address the cooperation problem in structured populations by considering the prisoner’s dilemma game as a metaphor of the social interactions between individuals with imitation capacity. We present a new strategy update rule called democratic weighted update where the individual’s behavior is socially influenced by each one of their neighbors. In particular, the capacity of an individual to socially influence other ones is proportional to its accumulated payoff. When in a neighborhood there are cooperators and defectors, the focal player is contradictorily influenced by them and, therefore, the effective social influence is given by the difference of the accumulated payoff of each strategy in its neighborhood. First, by considering the growing process of the network and neglecting mutations, we show the evolution of highly cooperative systems. Then, we broadly show that the social influence allows to overcome the emergence of defectors into highly cooperative systems. In this way, we conclude that in a structured system formed by a growing process, the cooperation evolves if the individuals have an imitation capacity socially influenced by each one of their neighbors. Therefore, here we present a theoretical solution of the cooperation problem among genetically unrelated individuals.

  10. Hereditary and Environmental Influences on Preschool Twins' Language Skills.

    ERIC Educational Resources Information Center

    Mather, Patricia L.; Black, Kathryn N.

    1984-01-01

    Examines genetic influences on language by assessing 158 preschool twins on vocabulary comprehension, semantic knowledge, morphology, syntax, and articulation. Vocabulary comprehension was significantly influenced by heredity, whereas performance skills were influenced by between-family environmental factors. (Author/AS)

  11. Influence Strategies for Systems of Systems

    NASA Astrophysics Data System (ADS)

    Shah, Nirav Bharat

    Distributed decision making has been identified as a source of managerial complexity for leaders of systems of systems (SoS). A new framework, AIR (Anticipation-Influence-Reaction), is proposed to capture the feedback relationships between the decisions made by constituents and those made by the managers of the SoS. AIR is then used to develop a five-member set of basic influences that can bring about changes in constituent behavior thus modifying the SoS. These influences, the 5 Is, are Incentives, Information, Infrastructure, Integration, and Institutions. AIR and the influences are demonstrated through qualitative application to real-world SoSs and quantitatively through simulation of an inter-modal freight transport network. It is found that cooperation between competing constituents, i.e., rail and truck carriers, can be quite fragile and sensitive to the SoS context. Careful, dynamic planning of influence strategies is needed to maintain SoS behavior in the face of constituents who are driven by self-interest and a limited, local perspective of the SoS. (Copies available exclusively from MIT Libraries, libraries.mit.edu/docs - docs mit.edu)

  12. 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 PMID:26727019

  13. Factors potentially influencing aminoglycoside use and expenditure

    SciTech Connect

    DiPiro, J.T.; Kilsdonk, G.F.; Amerson, A.B.; Record, K.E.

    1982-07-01

    Factors that may have influenced aminoglycoside use and expenditure in one hospital were examined. Factors that were evaluated as to their influence on aminoglycoside-use patterns were: (1) formulary status; (2) bacterial susceptibility patterns; (3) identified or perceived differences in toxicity; (4) changes in patient population; (5) price paid by the hospital for aminoglycosides; (6) distribution of newsletters or memoranda; (7) advertising and detailing; and (8) pharmacy policies. For FY 1976-77 to 1979-80, the largest proportion of aminoglycoside expense was for gentamicin. During FY 1980-81, the expenditure for gentamicin decreased and tobramycin accounted for the largest proportion of total expenditure. Monthly gentamicin use decreased 20% during FY 1980-81 from the previous year. Tobramycin use increased from January 1979 to November 1980 and decreased from December 1980 to June 1981. Kanamycin use and amikacin use were fairly constant during the study period. Based on temporal relationships, the following factors appeared to influence aminoglycoside use and expenditure: (1) a study conducted at the institution from June 1977 to June 1979 comparing gentamicin and tobramycin nephrotoxicity; (2) a comparative nephrotoxicity study published in a widely circulated medical journal in May 1980; and (3) an intramural newsletter and memorandum distributed in March 1981 encouraging selective aminoglycoside use. The identification of factors that potentially influenced aminoglycoside use can be used to anticipate the future impact of similar events and to devise strategies to influence antimicrobial use.

  14. Sensorimotor influences on speech perception in infancy.

    PubMed

    Bruderer, Alison G; Danielson, D Kyle; Kandhadai, Padmapriya; Werker, Janet F

    2015-11-01

    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. PMID:26460030

  15. 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.

  16. Using Network Dynamical Influence to Drive Consensus.

    PubMed

    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

  17. Role of collective influence in promoting cooperation

    NASA Astrophysics Data System (ADS)

    Huang, Z.-G.; Wu, Z.-X.; Wu, A.-C.; Yang, L.; Wang, Y.-H.

    2008-12-01

    The collective influence on the individuals' behavior have attracted much attention, and interesting phenomena such as social facilitation and social loafing have been studied. In this paper, we consider how the collective influence affects the evolution of cooperation in a structured population of individuals who nourish and benefit from public goods in groups. Individuals are supposed to distribute endowments to different groups to nourish the corresponding public goods. The collective influence is indicated by a tunable parameter α, with larger α corresponding to the players' higher preference to contribute more to the larger groups, which is similar to the social-facilitation effect in the real world, whereas, with smaller α corresponding to individuals' contrary preference, i.e., the social-loafing effect. Interestingly, we find that the heterogeneity of public-goods setting favors cooperation. Furthermore, the system where social loafing occurs performs better than that with social facilitation, in the case of heterogeneous formation.

  18. [The influence of face on person perception].

    PubMed

    Kawanishi, C

    1993-10-01

    The purpose is to examine the influence of three factors on person perception, (a) the degree of facial attractiveness, (b) the order of presentation of the faces and the verbal information of the same stimulus person and (c) the sex of the perceivers. Seventy-one male undergraduates and 89 female undergraduates were asked to rate the personalities of the two positive and two negative stimulus persons of the opposite sex, who were selected by each subject in preliminary experiment, and asked to choose what kind of relation they would have with them. Positive or negative face was presented either before or after verbal information. The main results were as follows. (a) Generally, positive faces exerted greater influence than negative faces. (b) Faces presented after verbal information were more influential than those presented before it (recency effect). (c) The influence of face on male subjects was greater than that on female subjects. PMID:8301890

  19. 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. PMID:25651572

  20. 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

  1. Top consumer abundance influences lake methane efflux.

    PubMed

    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

  2. Semantic information influences race categorization from faces.

    PubMed

    Tskhay, Konstantin O; Rule, Nicholas O

    2015-06-01

    It is well established that low-level visual features affect person categorization in a bottom-up fashion. Few studies have examined top-down influences, however, and have largely focused on how information recalled from memory or from motivation influences categorization. Here, we investigated how race categorizations are affected by the context in which targets are perceived by manipulating semantic information associated with the faces being categorized. We found that presenting faces that systematically varied in racial ambiguity with race-congruent (vs. incongruent) semantic labels shifted the threshold at which perceivers distinguished between racial groups. The semantic information offered by the labels therefore appeared to influence the categorization of race. These findings suggest that semantic information creates a context for the interpretation of perceptual cues during social categorization, highlighting an active role of top-down information in race perception. PMID:25810414

  3. 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

  4. 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

  5. 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…

  6. 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.

  7. 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. PMID:8324609

  8. 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

  9. 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. PMID:22654483

  10. 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. PMID:26110855

  11. Parasympathetic tonic dilatory influences on cerebral vessels.

    PubMed

    Boysen, Nicholas C; Dragon, Deidre Nitschke; Talman, William T

    2009-05-11

    Parasympathetic nerves from the pterygopalatine ganglia may participate in development of cluster headaches, in vascular responses to hypertension and in modulation of damage due to stroke. Stimulation of the nerves elicits cerebral vasodilatation, but it is not known if the nerves tonically influence cerebrovascular tone. We hypothesized that parasympathetics provide a tonic vasodilator influence and tested that hypothesis by measuring cerebral blood flow in anesthetized rats before and after removal of a pterygopalatine ganglion. Ganglion removal led to reduced cerebral blood flow without changing blood pressure. Thus, parasympathetic nerves provide tonic vasodilatory input to cerebral blood vessels. PMID:19195933

  12. Influence of essential elements on manganese intoxication

    SciTech Connect

    Khandelwal, S.; Ashquin, M.; Tandon, S.K.

    1984-01-01

    With a view to explore the influence of essential metals in manganese intoxication, the effect of calcium, iron or zinc supplementation on the uptake of manganese and on the activity of manganese sensitive enzymes, succinic dehydrogenase and cytochrome oxidase in brain and liver of rat was investigated. The choice of the two mitochondrial enzymes was based on the fact that the mitochondria are the chief site of manganese accumulation and their activity in brain, liver and blood of rats is significantly influenced by manganese.

  13. The Process of Social Influence: Readings in Persuasion.

    ERIC Educational Resources Information Center

    Beisecker, Thomas D., Ed.; Parson, Donn W., Ed.

    An attempt to synthesize primarily experimental studies of the process of social influence is presented. The point is made that each of us is involved in the process of social influence, both because we often attempt to influence someone else, and because we are constantly targets for attempts at social influence. This book is divided into four…

  14. 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…

  15. Peer Influences on Adolescent Cigarette Smoking: A Prospective Sibling Analysis.

    ERIC Educational Resources Information Center

    Rose, Jennifer S.; Chassin, Laurie; Presson, Clark C.; Sherman, Steven J.

    1999-01-01

    Studied role of nonshared parent and peer influences on siblings as predictors of adolescent cigarette smoking onset. Found peer influences were predictors of smoking onset when shared influences were controlled. Nonshared peer influences on siblings were stronger in educated families. Findings highlight utility of controlling for shared…

  16. Characteristics of Principal Leadership Influencing School Culture

    ERIC Educational Resources Information Center

    Hudson, Norma J.

    2012-01-01

    The primary purpose of this study is to examine characteristics of principal leadership influencing school culture as viewed by stakeholders involved in the International Schools Group (ISG) in Saudi Arabia. A secondary purpose of this study is to inform ISG educational leaders about the perspectives of their respective stakeholder groups…

  17. Power of Persuasion: Becoming the Influencer

    ERIC Educational Resources Information Center

    Johnson, William C.; Young, Norman

    2012-01-01

    The ability to effectively communicate an idea is as important as the idea itself. Facility managers are called on to perform an incredible variety of tasks taking into account a diverse group of stakeholders and multiple competing priorities. Becoming a powerful influencer and sharpening one's skills of persuasion will prove to be a fundamental…

  18. Values, Influences, and Peers (VIP) Program Review.

    ERIC Educational Resources Information Center

    Fine, Judith

    This report reviews the Values, Influences, and Peers (VIP) program in the Peel, Ontario schools. Originally developed as a joint initiative of the Ministry of Education and the Ministry of the Solicitor General, the VIP program was first introduced in Peel in 1983 as a pilot initiative in one school. Launched as a response to an increase in…

  19. 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…

  20. Classroom Instruction: The Influences of Marie Clay

    ERIC Educational Resources Information Center

    McNaughton, Stuart

    2014-01-01

    Marie Clay's body of work has influenced classroom instruction in direct and indirect ways, through large overarching themes in our pedagogical content knowledge as well as specific smart practices. This paper focuses on her the contributions to our thinking about instruction which come from two broad theoretical concepts; emergent literacy…

  1. Peer Group Influences on Adolescent Dating Aggression

    ERIC Educational Resources Information Center

    Connolly, Jennifer; Friedlander, Laura

    2009-01-01

    The peer group is a critical social context for dating and romantic relationships. Peer groups provide opportunities to meet potential dating partners and set norms for acceptable dating behaviors. This article explores how peer groups influence dating and dating aggression, as well as how they can be used in prevention efforts. It also reviews…

  2. Speed Variance and Its Influence on Accidents.

    ERIC Educational Resources Information Center

    Garber, Nicholas J.; Gadirau, Ravi

    A study was conducted to investigate the traffic engineering factors that influence speed variance and to determine to what extent speed variance affects accident rates. Detailed analyses were carried out to relate speed variance with posted speed limit, design speeds, and other traffic variables. The major factor identified was the difference…

  3. Influences on Community College Students' Educational Plans.

    ERIC Educational Resources Information Center

    Pascarella, Ernest T.; Wolniak, Gregory C.; Pierson, Christopher T.

    2003-01-01

    Identified the institutional and college experience variables influencing end-of-first-year educational degree plans of community college students. Found that the average precollege degree plans at a community college had a significant effect on students' end-of-first-year degree plans. In the prediction of end-of-first-year degree plans, there…

  4. Collective influence in evolutionary social dilemmas

    NASA Astrophysics Data System (ADS)

    Szolnoki, Attila; Perc, Matjaž

    2016-03-01

    When evolutionary games are contested in structured populations, the degree of each player in the network plays an important role. If they exist, hubs often determine the fate of the population in remarkable ways. Recent research based on optimal percolation in random networks has shown, however, that the degree is neither the sole nor the best predictor of influence in complex networks. Low-degree nodes may also be optimal influencers if they are hierarchically linked to hubs. Taking this into account leads to the formalism of collective influence in complex networks, which as we show here, has far-reaching implications for the favorable resolution of social dilemmas. In particular, there exists an optimal hierarchical depth for the determination of collective influence that we use to describe the potency of players for passing their strategies, which depends on the strength of the social dilemma. Interestingly, the degree, which corresponds to the baseline depth zero, is optimal only when the temptation to defect is small. Our research reveals that evolutionary success stories are related to spreading processes which are rooted in favorable hierarchical structures that extend beyond local neighborhoods.

  5. Influences of Mood on Academic Course Evaluations

    ERIC Educational Resources Information Center

    Zumbach, Joerg; Funke, Joachim

    2014-01-01

    In two subsequent experiments, the influence of mood on academic course evaluation is examined. By means of facial feedback, either a positive or a negative mood was induced while students were completing a course evaluation questionnaire during lectures. Results from both studies reveal that a positive mood leads to better ratings of different…

  6. 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…

  7. The Influence of Attitudes about Weight

    ERIC Educational Resources Information Center

    Journal of Physical Education, Recreation & Dance (JOPERD), 2005

    2005-01-01

    Obesity stereotypes and anti fat attitudes influence the social behavior of middle school students according to a study presented last June at the annual meeting of the American College of Sports Medicine (ACSM). Using a series of questionnaires and fat and thin silhouette figures, the researchers quizzed 176 boys and 141 girls between the ages of…

  8. Influencing Database Use in Public Libraries.

    ERIC Educational Resources Information Center

    Tenopir, Carol

    1999-01-01

    Discusses results of a survey of factors influencing database use in public libraries. Highlights the importance of content; ease of use; and importance of instruction. Tabulates importance indications for number and location of workstations, library hours, availability of remote login, usefulness and quality of content, lack of other databases,…

  9. When can attention influence binocular rivalry?

    PubMed

    Dieter, Kevin C; Melnick, Michael D; Tadin, Duje

    2015-08-01

    Attentional influence over perception is particularly pronounced when sensory stimulation is ambiguous, where attention can reduce stimulus uncertainty and promote a stable interpretation of the world. However, binocular rivalry, an extensively studied visual ambiguity, has proved to be comparatively resistant to attentional modulation. We hypothesize that this apparent inconsistency reflects fluctuations in the degree of unresolved competition during binocular rivalry. Namely, attentional influence over rivalry dynamics should be limited to phases of relatively unresolved stimulus competition, such as ends of individual dominance periods. We found that transient, feature-based cues congruent with the dominant stimulus prolonged dominance durations, while cues matching the suppressed stimulus hastened its return to dominance. Notably, the effect of cues depended on when the cues are presented. Cues presented late, but not early, during a given episode of perceptual dominance influenced rivalry dynamics. This temporal pattern mirrors known changes in the relative competitive dynamics of rival stimuli, revealing that selective effects occur only during temporal windows containing weak resolution of visual competition. In conclusion, these findings reveal that unresolved competition, which gates attention across a variety of domains, is also crucial in determining the susceptibility of binocular rivalry to selective influences. PMID:25898898

  10. Ion Exchange Membrane Influence on Ohmic Resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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 ...

  11. Positioning Mathematics Education Researchers to Influence Storylines

    ERIC Educational Resources Information Center

    Herbel-Eisenmann, Beth; Sinclair, Nathalie; Chval, Kathryn B.; Clements, Douglas H.; Civil, Marta; Pape, Stephen J.; Stephan, Michelle; Wanko, Jeffrey J.; Wilkerson, Trena L.

    2016-01-01

    The NCTM Research Committee identifies key influences on mathematics education that are largely outside the domain of the academic world in which most mathematics education researchers live. The groups that are identified--including the media, companies and foundations, and other academic domains--affect the public's perception of mathematics and…

  12. Value Perceptions as Influences upon Engagement

    ERIC Educational Resources Information Center

    Swanson, Lee A.

    2009-01-01

    This study was designed to assess whether changes in stakeholders' perceptions about the value generated by an institution might influence the nature of their engagement with it. Quantitative and qualitative analysis of research data revealed a positive correlation between stakeholders who believed an institution generated social or economic value…

  13. Factors Influencing High School Students' Career Aspirations

    ERIC Educational Resources Information Center

    Tang, Mei; Pan, Wei; Newmeyer, Mark D.

    2008-01-01

    This article explores the factors influencing high school students' career aspirations with a study analyzing 141 high school students. The Social Cognitive Career Development Model was utilized to examine the interactive relationships among learning experiences, career self-efficacy, outcome expectations, career interests, and career choices. The…

  14. 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…

  15. Disciplinary Exclusion: The Influence of School Ethos

    ERIC Educational Resources Information Center

    Hatton, Lucy Ann

    2013-01-01

    Disciplinary exclusion is a strategy used by some schools in response to challenging behaviour. While some studies have explored interventions that can be implemented to reduce the exclusion of "at risk" pupils, others have considered how the underlying school ethos influences how challenging behaviour is understood and managed. The current study…

  16. 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…

  17. Motivational Influences on School-Prompted Interest

    ERIC Educational Resources Information Center

    Ciani, Keith; Ferguson, Yuna; Bergin, David; Hilpert, Jonathan

    2010-01-01

    Some argue that the goal of education is to influence out-of-school learning activity, yet little research exists on how teachers can help students develop an interest in a topic and continue to pursue that interest outside of school. The current study tested classroom context variables from self-determination theory (teachers' autonomy support)…

  18. Jungian Influenced Therapists and Buddhists in Dialogue

    ERIC Educational Resources Information Center

    West, William; Goss, Phil

    2016-01-01

    This paper presents the findings from the second of an ongoing series of focus group encounters between spiritually minded counsellors and those engaged in pastoral care within a religious tradition. For this study we recruited five Jungian influenced therapists and three pastoral care workers two of whom were explicitly Buddhists. The data was…

  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. Production Decline Analysis Using Influence Functions

    SciTech Connect

    Zais, Elliot J.

    1980-12-16

    We previously reported (Zais, 1979) that Arps's exponential equation works quite well on geothermal production data. The hyperbolic equation should probably not be used. In this paper we show the progress made i n using influence functions t o describe reservoir production behavior.

  1. Simmel's Influence on American Sociology. II

    ERIC Educational Resources Information Center

    Levine, Donald N.; And Others

    1976-01-01

    This article constitutes the second part of a discussion of the diffusion of Georg Simmel's thought within the American sociological community first initiated in the January issue of this journal (See SO 504 694). His influence is traced with respect to metropolitan mentality, small groups, interpersonal knowledge, conflict, and exchange. (Author)

  2. 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

  3. 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…

  4. Node influence identification via resource allocation dynamics

    NASA Astrophysics Data System (ADS)

    Ma, Shu-Jiao; Ren, Zhuo-Ming; Ye, Chun-Ming; Guo, Qiang; Liu, Jian-Guo

    2014-07-01

    Identifying the node influence in complex networks is an important task to optimally use the network structure and ensure the more efficient spreading in information. In this paper, by taking into account the resource allocation dynamics (RAD) and the k-shell decomposition method, we present an improved method namely RAD to generate the ranking list to evaluate the node influence. First, comparing with the epidemic process results for four real networks, the RAD method could identify the node influence more accurate than the ones generated by the topology-based measures including the degree, k-shell, closeness and the betweenness. Then, a growing scale-free network model with tunable assortative coefficient is introduced to analyze the effect of the assortative coefficient on the accuracy of the RAD method. Finally, the positive correlation is found between the RAD method and the k-shell values which display an exponential form. This work would be helpful for deeply understanding the node influence of a network.

  5. Practitioners Influence Curriculum Theory: Autobiographical Reflections.

    ERIC Educational Resources Information Center

    Schubert, William H.

    1992-01-01

    Examines dimensions of theoretical perspective on curriculum, noting influences of teachers who were the author's graduate students. The article covers curriculum theorizing, synoptic and historical portrayals, comparative orientations, ideological considerations, teacher/student lore, outside curriculum, preservice/inservice teacher education…

  6. 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…

  7. Factors Influencing Learning at a Community College.

    ERIC Educational Resources Information Center

    Johnson, Marvin L.

    The Walberg Educational Productivity Model theorizes that learning in its affective, behavioral, and cognitive aspects is causally influenced by factors in the areas of individual aptitude (i.e., prior achievement, age or stage of maturation, and motivation), instructional treatment (i.e., quantity of time spent in learning situations and…

  8. Factors Influencing the Successful Introduction of Portfolios

    ERIC Educational Resources Information Center

    Van Tartwijk, Jan; Driessen, Erik; Van Der Vleuten, Cees; Stokking, Karel

    2007-01-01

    Factors influencing the successful introduction of portfolios are described. A portfolio is a purposeful collection of all kinds of documents and other artefacts that together give an impression of how tasks were fulfilled and how competence has developed. A portfolio can also contain reflections and plans for future development. Although…

  9. How Physical Design Can Influence Copyright Compliance

    ERIC Educational Resources Information Center

    Harper, Meghan

    2007-01-01

    Most school librarians do not think of copyright compliance and facilities planning in the same breath. Yet the design of space--physical and virtual--can discourage or promote compliance, or even help police it. Placement of and access to equipment, traffic patterns, signage, and student workspace all may influence copyright-compliance behavior…

  10. Friend Influence on Achievement during Middle Childhood

    ERIC Educational Resources Information Center

    DeLay, Dawn

    2013-01-01

    This study was designed to investigate friend influence on academic achievement and task avoidance during middle childhood in a sample of 794 participants in 397 stable same-sex friendship dyads (205 girl dyads and 192 boy dyads) from four municipalities in Finland: two in Central Finland, one in Western Finland, and one in Eastern Finland.…

  11. 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…

  12. Factors Influencing L2 Gender Processing

    ERIC Educational Resources Information Center

    Bordag, Denisa; Pechmann, Thomas

    2007-01-01

    In four experiments we explored processes underlying L2 gender retrieval. We focused on L1 interference and on the influence of the L2 noun's termination. In Experiments 1 and 2 we tried to manipulate the intensity of L1 interference. We found that L2 speakers cannot eliminate or substantially reduce the interlingual interference neither when they…

  13. Influence of characteristics on combined sewer performance.

    PubMed

    Möderl, M; Kleidorfer, M; Rauch, W

    2012-01-01

    Elements of combined sewer systems are among others sub-catchments, junctions, conduits and weirs with or without storage units. The spatial distribution and attributes of all these elements influence both system characteristics and sewer performance. Until today, little work has been done to analyse the influence of such characteristics in a case unspecific approach. In this study, 250 virtual combined sewer systems are analysed by defining groups of systems, which are representative for their different characteristics. The set was created with a further development of the case study generator (CSG), a tool for automatic generation of branched sewer systems. Combined sewer overflow and flooding is evaluated using performance indicators based on hydrodynamic simulations. The analysis of system characteristics, like those presented in this paper, helps researchers to understand coherences and aids practitioners in designing combined sewers. For instance, it was found that characteristics that have a positive influence on emission reduction frequently have a negative influence on flooding avoidance and vice versa. PMID:22797234

  14. The Influence of CASE on Scientific Creativity.

    ERIC Educational Resources Information Center

    Lin, Chongde; Hu, Weiping; Adey, Philip; Shen, Jiliang

    2003-01-01

    Describes a study of the influence of the Cognitive Acceleration through Science Education (CASE) program on the scientific creativity of secondary school students. Scientific creativity is measured by the Scientific Creativity Test for Secondary School Students. Results indicate that the program did promote the overall development of scientific…

  15. 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…

  16. 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…

  17. Perceiving Virtual Geographical Slant: Action Influences Perception

    ERIC Educational Resources Information Center

    Creem-Regehr, Sarah H.; Gooch, Amy A.; Sahm, Cynthia S.; Thompson, William B.

    2004-01-01

    In 4 experiments, the authors varied the extent and nature of participant movement in a virtual environment to examine the influence of action on estimates of geographical slant. Previous studies showed that people consciously overestimate hill slant but can still accurately guide an action toward the hill (D. R. Proffitt, M. Bhalla, R.…

  18. 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…

  19. Older Siblings Influence Younger Siblings' Motor Development

    ERIC Educational Resources Information Center

    Berger, Sarah E.; Nuzzo, Katie

    2008-01-01

    Evidence exists for two competing theories about the effects of having an older sibling on development. Previous research has found that having an older sibling has both advantages and disadvantages for younger siblings' development. This study examined whether and how older siblings influenced the onset of their own younger siblings' motor…

  20. Educational Expertise, Advocacy, and Media Influence

    ERIC Educational Resources Information Center

    Malin, Joel R.; Lubienski, Christopher

    2015-01-01

    The efforts of many advocacy organizations to advance their preferred policies despite conflicting evidence of the effectiveness of these policies raise questions about factors that shape successful policy promotion. While many may like to think that expertise on an issue in question is an essential prerequisite for influence in public policy…

  1. Immunological Influences on the Vestibular System

    NASA Technical Reports Server (NTRS)

    Warchol, Mark E.

    2003-01-01

    The goals of this project were to examine the influence of immune signaling molecules on the survival and replacement of sensory hair cells in the vestibular organs. We have made considerable progress toward that goal, particularly in the characterization of mechanisms that underlie hair cell death.

  2. Introduction: Influences on College Student Learning.

    ERIC Educational Resources Information Center

    Braxton, John M.

    2002-01-01

    Introduces a collection of articles that reflect on the complexity of college teaching and learning by acknowledging that teaching and learning at the collegiate level occur within a system of both external and internal influences that are political, organizational, social, and psychological in nature. (SM)

  3. 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…

  4. Influence of metabolic pathways on dam longevity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Metabolism is an ever-changing dynamic system that can influence various physiological conditions including reproductive performance. It has been established that use of caloric restriction can enhance lifespan. But, it is also a well known fact that high energy demands in tandem with moderate to ...

  5. Technology Education Graduate Education: Factors Influencing Participation.

    ERIC Educational Resources Information Center

    Cardon, Phillip L.; Rogers, George E.

    A modified Delphi technique was used to identify the factors that positively influence technology education teachers' decision to enroll in graduate education programs and the barriers to their enrollment in advanced degree programs. Two pairs of Delphi panels were established. The doctoral panels consisted of 15 recent doctoral graduates and 30…

  6. 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…

  7. 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

  8. The Influence of Palatoplasty on Eating Function.

    PubMed

    Fujikawa, Heishiro; Wakami, Satoki; Motomura, Hisashi

    2016-08-01

    Postoperative dietary control and surgical procedures are important for minimizing complications after a palatoplasty because the palate is always exposed to stresses by various movements associated with eating. Currently, we provide fluid foods (food paste, liquid food, and soft food) to postpalatoplasty patients. However, nutritional inadequacies associated with fluid food necessitate the need to develop a new food specifically for postpalatoplasty patients. Although evaluating the influence of a palatoplasty on eating function is important for the development of a new diet, no data have been published on this topic. Thus, to evaluate the influence of a palatoplasty on eating function, we analyzed postoperative changes in the eating condition of cleft palate patients. We performed a retrospective study. All participants had undergone surgery for a cleft palate at our hospital. Nurses recorded the amount of food that patients consumed as a ratio of the whole meal, and we extracted data on the food type and the amount consumed at each meal from their medical records. After the ratio was expressed as a percentage of the whole meal (eating rate), we calculated the mean value of the percentage of the subject group and examined chronological changes. The eating rate was very low on postoperative day 1, it improved over time and was constant on postoperative day 7. From this result, we concluded that palatoplasty greatly influences the eating function of patients, and the influence lasts for at least a week after surgery. PMID:27622108

  9. The Influence of Palatoplasty on Eating Function

    PubMed Central

    Wakami, Satoki; Motomura, Hisashi

    2016-01-01

    Summary: Postoperative dietary control and surgical procedures are important for minimizing complications after a palatoplasty because the palate is always exposed to stresses by various movements associated with eating. Currently, we provide fluid foods (food paste, liquid food, and soft food) to postpalatoplasty patients. However, nutritional inadequacies associated with fluid food necessitate the need to develop a new food specifically for postpalatoplasty patients. Although evaluating the influence of a palatoplasty on eating function is important for the development of a new diet, no data have been published on this topic. Thus, to evaluate the influence of a palatoplasty on eating function, we analyzed postoperative changes in the eating condition of cleft palate patients. We performed a retrospective study. All participants had undergone surgery for a cleft palate at our hospital. Nurses recorded the amount of food that patients consumed as a ratio of the whole meal, and we extracted data on the food type and the amount consumed at each meal from their medical records. After the ratio was expressed as a percentage of the whole meal (eating rate), we calculated the mean value of the percentage of the subject group and examined chronological changes. The eating rate was very low on postoperative day 1, it improved over time and was constant on postoperative day 7. From this result, we concluded that palatoplasty greatly influences the eating function of patients, and the influence lasts for at least a week after surgery.

  10. How to Influence the IDEA Regulations

    ERIC Educational Resources Information Center

    Dale, Richard E.

    2011-01-01

    Teachers of children with disabilities know how greatly the Individuals With Disabilities Education Act (IDEA) regulations influence their daily practices; and they no doubt have strong opinions about regulations that go too far or not far enough to allow them to help their students succeed. This article offers practical, nuts-and-bolts help for…

  11. Factors Influencing Curricular Reform; An Irish Perspective

    ERIC Educational Resources Information Center

    Ferris, Helena; Joyce, Pauline

    2015-01-01

    There are various influences and obstacles when planning an educational curriculum. The imprint of globalisation on the landscape of Irish medicine highlights the importance of delivering a diverse curriculum with international dimensions so that knowledge and skills can transfer across borders. It is also clear that medical emigration has a…

  12. Screening for Multiple Genes Influencing Dyslexia.

    ERIC Educational Resources Information Center

    Smith, Shelley D.; And Others

    1991-01-01

    Examines the "sib pair" method of linkage analysis designed to locate genes influencing dyslexia, which has several advantages over the "LOD" score method. Notes that the sib pair analysis was able to detect the same linkages as the LOD method, plus a possible third region. Confirms that the sib pair method is an effective means of screening. (RS)

  13. Factors Influencing Teaching Choice in Turkey

    ERIC Educational Resources Information Center

    Kilinc, Ahmet; Watt, Helen M. G.; Richardson, Paul W.

    2012-01-01

    Why choose to become a teacher in Turkey? The authors examined motivations and perceptions among preservice teachers (N = 1577) encompassing early childhood, primary and secondary education. The Factors Influencing Teaching Choice (FIT-Choice) instrument was translated into Turkish and its construct validity and reliability assessed. Altruistic…

  14. Wind influence on a coastal buoyant outflow

    NASA Astrophysics Data System (ADS)

    Whitney, Michael M.; Garvine, Richard W.

    2005-03-01

    This paper investigates the interplay between river discharge and winds in forcing coastal buoyant outflows. During light winds a plume influenced by the Earth's rotation will flow down shelf (in the direction of Kelvin wave propagation) as a slender buoyancy-driven coastal current. Downwelling favorable winds augment this down-shelf flow, narrow the plume, and mix the water column. Upwelling favorable winds drive currents that counter the buoyancy-driven flow, spread plume waters offshore, and rapidly mix buoyant waters. Two criteria are developed to assess the wind influence on a buoyant outflow. The wind strength index (Ws) determines whether a plume's along-shelf flow is in a wind-driven or buoyancy-driven state. Ws is the ratio of the wind-driven and buoyancy-driven along-shelf velocities. Wind influence on across-shelf plume structure is rated with a timescale (ttilt) for the isopycnal tilting caused by wind-driven Ekman circulation. These criteria are used to characterize wind influence on the Delaware Coastal Current and can be applied to other coastal buoyant outflows. The Delaware buoyant outflow is simulated for springtime high-river discharge conditions. Simulation results and Ws values reveal that the coastal current is buoyancy-driven most of the time (∣Ws∣ < 1 on average). Wind events, however, overwhelm the buoyancy-driven flow (∣Ws∣ > 1) several times during the high-discharge period. Strong upwelling events reverse the buoyant outflow; they constitute an important mechanism for transporting fresh water up shelf. Across-shelf plume structure is more sensitive to wind influence than the along-shelf flow. Values of ttilt indicate that moderate or strong winds persisting throughout a day can modify plume width significantly. Plume widening during upwelling events is accompanied by mixing that can erase the buoyant outflow.

  15. Sensorimotor influences on speech perception in infancy

    PubMed Central

    Bruderer, Alison G.; Danielson, D. Kyle; Kandhadai, Padmapriya; Werker, Janet F.

    2015-01-01

    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. PMID:26460030

  16. Arsenic in benthic bivalves of San Francisco Bay and the Sacramento/San Joaquin River Delta

    USGS Publications Warehouse

    Johns, C.; Luoma, S.N.

    1990-01-01

    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.

  17. Having influence: faculty of color having influence in schools of nursing.

    PubMed

    Hassouneh, Dena; Lutz, Kristin F

    2013-01-01

    Faculty of color (FOC) play an important role in mentoring students and other FOC in schools of nursing. However, the unique nature of mentoring that FOC provide, which includes transmission of expert knowledge of the operations of racism in nursing academe, is not well understood. Furthermore, the influence FOC have on school cultures has not been well documented. To address this gap in knowledge we conducted a critical grounded theory study with 23 FOC in predominately Euro-American schools of nursing. Findings indicate that FOC Having Influence is a key process that explicates the influence FOC wield, exposing their work, which is often taken for granted, hidden, and, unacknowledged. FOC Having Influence occurred in two areas: 1) the survival and success of students and FOC and 2) shaping practices in schools of nursing and impacting health in communities. Implications for educational practice and future research are presented, based on study findings. PMID:23158848

  18. Influence of Lift Offset on Rotorcraft Performance

    NASA Technical Reports Server (NTRS)

    Johnson, Wayne

    2009-01-01

    The influence of lift offset on the performance of several rotorcraft configurations is explored. A lift-offset rotor, or advancing blade concept, is a hingeless rotor that can attain good efficiency at high speed by operating with more lift on the advancing side than on the retreating side of the rotor disk. The calculated performance capability of modern-technology coaxial rotors utilizing a lift offset is examined, including rotor performance optimized for hover and high-speed cruise. The ideal induced power loss of coaxial rotors in hover and twin rotors in forward flight is presented. The aerodynamic modeling requirements for performance calculations are evaluated, including wake and drag models for the high-speed flight condition. The influence of configuration on the performance of rotorcraft with lift-offset rotors is explored, considering tandem and side-by-side rotorcraft as well as wing-rotor lift share.

  19. Learning Delayed Influences of Biological Systems

    PubMed Central

    Ribeiro, Tony; Magnin, Morgan; Inoue, Katsumi; Sakama, Chiaki

    2015-01-01

    Boolean networks are widely used model to represent gene interactions and global dynamical behavior of gene regulatory networks. To understand the memory effect involved in some interactions between biological components, it is necessary to include delayed influences in the model. In this paper, we present a logical method to learn such models from sequences of gene expression data. This method analyzes each sequence one by one to iteratively construct a Boolean network that captures the dynamics of these observations. To illustrate the merits of this approach, we apply it to learning real data from bioinformatic literature. Using data from the yeast cell cycle, we give experimental results and show the scalability of the method. We show empirically that using this method we can handle millions of observations and successfully capture delayed influences of Boolean networks. PMID:25642421

  20. Octopamine influences honey bee foraging preference.

    PubMed

    Giray, Tugrul; Galindo-Cardona, Alberto; Oskay, Devrim

    2007-07-01

    Colony condition and differences in individual preferences influence forage type collected by bees. Physiological bases for the changing preferences of individual foragers are just beginning to be examined. Recently, for honey bees octopamine is shown to influence age at onset of foraging and probability of dance for rewards. However, octopamine has not been causally linked with foraging preference in the field. We tested the hypothesis that changes in octopamine may alter forage type (preference hypothesis). We treated identified foragers orally with octopamine or its immediate precursor, tyramine, or sucrose syrup (control). Octopamine-treated foragers switched type of material collected; control bees did not. Tyramine group results were not different from the control group. In addition, sugar concentrations of nectar collected by foragers after octopamine treatment were lower than before treatment, indicating change in preference. In contrast, before and after nectar concentrations for bees in the control group were similar. These results, taken together, support the preference hypothesis. PMID:17574568

  1. How does ecological disturbance influence genetic diversity?

    PubMed

    Banks, Sam C; Cary, Geoffrey J; Smith, Annabel L; Davies, Ian D; Driscoll, Don A; Gill, A Malcolm; Lindenmayer, David B; Peakall, Rod

    2013-11-01

    Environmental disturbance underpins the dynamics and diversity of many of the ecosystems of the world, yet its influence on the patterns and distribution of genetic diversity is poorly appreciated. We argue here that disturbance history may be the major driver that shapes patterns of genetic diversity in many natural populations. We outline how disturbance influences genetic diversity through changes in both selective processes and demographically driven, selectively neutral processes. Our review highlights the opportunities and challenges presented by genetic approaches, such as landscape genomics, for better understanding and predicting the demographic and evolutionary responses of natural populations to disturbance. Developing this understanding is now critical because disturbance regimes are changing rapidly in a human-modified world. PMID:24054910

  2. Octopamine influences honey bee foraging preference

    PubMed Central

    Giray, Tugrul; Galindo, Alberto; Oskay, Devrim

    2010-01-01

    Colony condition and differences in individual preferences influence forage type collected by bees. Physiological bases for the changing preferences of individual foragers are just beginning to be examined. Recently, for honey bees octopamine is shown to influence age at onset of foraging and probability of dance for rewards. However, octopamine has not been causally linked with foraging preference in the field. We tested the hypothesis that changes in octopamine may alter forage type (preference hypothesis). We treated identified foragers orally with octopamine or its immediate precursor, tyramine, or sucrose syrup (control). Octopamine treated foragers switched type of material collected, control bees did not. Tyramine group results were not different from the control group. In addition, sugar concentrations of nectar collected by foragers after octopamine treatment were lower than before treatment, indicating change in preference. In contrast, before and after nectar concentrations for bees in the control group were similar. These results, taken together, support the preference hypothesis. PMID:17574568

  3. Tide-influenced sedimentary environments and facies

    SciTech Connect

    De Boer, P.L.; Van Gelder, A.; Nio, S.D.

    1988-01-01

    This volume contains examples of recent as well as fossil tide-influenced sedimentary facies. Studies of recent tidal processes and sediments provide an insight into the way in which tidal facies and sequences develop, and into the processes which are active. The studies performed on fossil rocks give information on one-to-one scale model experiments that have been executed by nature both relatively recently and in the distant past. In this work, the parallel presentation of papers on recent and fossil examples of tide-influenced sedimentary facies and environments follows the philosophy of comparative sedimentology, aiming at an understanding of both the past and the present, with the aim also, of forecasting future developments.

  4. How expert advice influences decision making.

    PubMed

    Meshi, Dar; Biele, Guido; Korn, Christoph W; Heekeren, Hauke R

    2012-01-01

    People often use expert advice when making decisions in our society, but how we are influenced by this advice has yet to be understood. To address this, using functional magnetic resonance imaging, we provided expert and novice advice to participants during an estimation task. Participants reported that they valued expert advice more than novice advice, and activity in the ventral striatum correlated with this valuation, even before decisions with the advice were made. When using advice, participants compared their initial opinion to their advisor's opinion. This comparison, termed the "opinion difference", influenced advice utilization and was represented in reward-sensitive brain regions. Finally, the left lateral orbitofrontal cortex integrated both the size of the opinion difference and the advisor's level of expertise, and average activity in this area correlated with mean advice utilization across participants. Taken together, these findings provide neural evidence for how advice engenders behavioral change during the decision-making process. PMID:23185425

  5. The ripple effect: patients influencing others.

    PubMed

    Paniagua, Cecilio

    2012-10-01

    This paper deals with what seems an insufficiently explored aspect of psychoanalytic practice: the ripple effect of a patient's evolution on the present and future of his or her significant others. Clinical vignettes are provided to illustrate patients' influence on relatives; patients acting as therapists; psychoanalysis by proxy; the ripple effect in psychotherapy; and some countertransference problems. The psychic lives of individuals not in treatment may be considerably affected by their interactions with our patients; seemingly, extraclinical character adjustments may ensue. Sociological findings and plausible psychodynamic explanations are discussed. A psychoanalytic perspective may not only help the analyst understand how therapeutic influence extends beyond the identified patient, but may also help guide interventions that are ripple-effective, even when they depart from classical analytic technique. PMID:23327000

  6. How Expert Advice Influences Decision Making

    PubMed Central

    Meshi, Dar; Biele, Guido; Korn, Christoph W.; Heekeren, Hauke R.

    2012-01-01

    People often use expert advice when making decisions in our society, but how we are influenced by this advice has yet to be understood. To address this, using functional magnetic resonance imaging, we provided expert and novice advice to participants during an estimation task. Participants reported that they valued expert advice more than novice advice, and activity in the ventral striatum correlated with this valuation, even before decisions with the advice were made. When using advice, participants compared their initial opinion to their advisor’s opinion. This comparison, termed the “opinion difference”, influenced advice utilization and was represented in reward-sensitive brain regions. Finally, the left lateral orbitofrontal cortex integrated both the size of the opinion difference and the advisor’s level of expertise, and average activity in this area correlated with mean advice utilization across participants. Taken together, these findings provide neural evidence for how advice engenders behavioral change during the decision-making process. PMID:23185425

  7. New parameters influencing hydraulic runner lifetime

    NASA Astrophysics Data System (ADS)

    Sabourin, M.; Thibault, D.; Bouffard, D. A.; Lévesque, M.

    2010-08-01

    Traditionally, hydraulic runner mechanical design is based on calculation of static stresses. Today, validation of hydraulic runner design in terms of reliability requires taking into account the fatigue effect of dynamics loads. A damage tolerant approach based on fracture mechanics is the method chosen by Alstom and Hydro-Québec to study fatigue damage in runners. This requires a careful examination of all factors influencing material fatigue behavior. Such material behavior depends mainly on the chemical composition, microstructure and thermal history of the component, and on the resulting residual stresses. Measurement of fracture mechanics properties of various steels have demonstrated that runner lifetime can be significantly altered by differences in the manufacturing process, although remaining in accordance with agreed practices and standards such as ASTM. Carbon content and heat treatment are suspected to influence fatigue lifetime. This will have to be investigated by continuing the current research.

  8. Influence of Lift Offset on Rotorcraft Performance

    NASA Technical Reports Server (NTRS)

    Johnson, Wayne

    2008-01-01

    The influence of lift offset on the performance of several rotorcraft configurations is explored. A lift-offset rotor, or advancing blade concept, is a hingeless rotor that can attain good efficiency at high speed, by operating with more lift on the advancing side than on the retreating side of the rotor disk. The calculated performance capability of modern-technology coaxial rotors utilizing a lift offset is examined, including rotor performance optimized for hover and high-speed cruise. The ideal induced power loss of coaxial rotors in hover and twin rotors in forward flight is presented. The aerodynamic modeling requirements for performance calculations are evaluated, including wake and drag models for the high speed flight condition. The influence of configuration on the performance of rotorcraft with lift-offset rotors is explored, considering tandem and side-by-side rotorcraft as well as wing-rotor lift share.

  9. Social influence effects on automatic racial prejudice.

    PubMed

    Lowery, B S; Hardin, C D; Sinclair, S

    2001-11-01

    Although most research on the control of automatic prejudice has focused on the efficacy of deliberate attempts to suppress or correct for stereotyping, the reported experiments tested the hypothesis that automatic racial prejudice is subject to common social influence. In experiments involving actual interethnic contact, both tacit and expressed social influence reduced the expression of automatic prejudice, as assessed by two different measures of automatic attitudes. Moreover, the automatic social tuning effect depended on participant ethnicity. European Americans (but not Asian Americans) exhibited less automatic prejudice in the presence of a Black experimenter than a White experimenter (Experiments 2 and 4), although both groups exhibited reduced automatic prejudice when instructed to avoid prejudice (Experiment 3). Results are consistent with shared reality theory, which postulates that social regulation is central to social cognition. PMID:11708561

  10. Commensal microbiota influence systemic autoimmune responses

    PubMed Central

    Van Praet, Jens T; Donovan, Erin; Vanassche, Inge; Drennan, Michael B; Windels, Fien; Dendooven, Amélie; Allais, Liesbeth; Cuvelier, Claude A; van de Loo, Fons; Norris, Paula S; Kruglov, Andrey A; Nedospasov, Sergei A; Rabot, Sylvie; Tito, Raul; Raes, Jeroen; Gaboriau-Routhiau, Valerie; Cerf-Bensussan, Nadine; Van de Wiele, Tom; Eberl, Gérard; Ware, Carl F; Elewaut, Dirk

    2015-01-01

    Antinuclear antibodies are a hallmark feature of generalized autoimmune diseases, including systemic lupus erythematosus and systemic sclerosis. However, the processes underlying the loss of tolerance against nuclear self-constituents remain largely unresolved. Using mice deficient in lymphotoxin and Hox11, we report that approximately 25% of mice lacking secondary lymphoid organs spontaneously develop specific antinuclear antibodies. Interestingly, we find this phenotype is not caused by a defect in central tolerance. Rather, cell-specific deletion and in vivo lymphotoxin blockade link these systemic autoimmune responses to the formation of gut-associated lymphoid tissue in the neonatal period of life. We further demonstrate antinuclear antibody production is influenced by the presence of commensal gut flora, in particular increased colonization with segmented filamentous bacteria, and IL-17 receptor signaling. Together, these data indicate that neonatal colonization of gut microbiota influences generalized autoimmunity in adult life. PMID:25599993

  11. Arieti and Bowlby: convergence and direct influence.

    PubMed

    Bacciagaluppi, Marco

    2015-09-01

    Arieti was a great specialist of schizophrenia and Bowlby was the initiator of attachment theory. Working independently on the two sides of the Atlantic, they converged on a range of topics, such as evolutionary theory, mourning, trauma, violence, and therapy as art and science. Later, Bowlby exerted a direct influence on Arieti, which Arieti acknowledged in his Love Can Be Found. Finally, the two authors cooperated in the second edition of the American Handbook of Psychiatry. PMID:26356777

  12. Influencing factor on the prognosis of arthrocentesis

    PubMed Central

    Kim, Yoon Ho; Jeong, Tae Min; Pang, Kang Mi

    2014-01-01

    Objectives The purpose of this article is to evaluate factors influencing prognosis of arthrocentesis in patients with temporomandibular joint (TMJ) disorder. Materials and Methods The subjects included 145 patients treated with arthrocentesis at the Dental Center of Ajou University Hospital from 2011 to 2013 for the purpose of recovering mouth opening limitation (MOL) and pain relief. Prognosis of arthrocentesis was evaluated 1 month after the operation. Improvement on MOL was defined as an increase from below 30 mm (MOL ≤30 mm) to above 40 mm (MOL ≥40 mm), and pain relief was defined as when a group with TMJ pain with a visual analog scale (VAS) score of 4 or more (VAS ≥4) decreased to a score of 3 or more. The success of arthrocentesis was determined when either mouth opening improved or pain relief was fulfilled. To determine the factors influencing the success of arthrocentesis, the patients were classified by age, gender, diagnosis group (the anterior disc displacement without reduction group, the anterior disc displacement with reduction group, or other TMJ disorders group), time of onset and oral habits (clenching, bruxism) to investigate the correlations between these factors and prognosis. Results One hundred twenty out of 145 patients who underwent arthrocentesis (83.4%) were found to be successful. Among the influencing factors mentioned above, age, diagnosis and time of onset had no statistically significant correlation with the success of arthrocentesis. However, a group of patients in their fifties showed a lower success rate (ANOVA P=0.053) and the success rate of the group with oral habits was 71% (Pearson's chi-square test P=0.035). Conclusion From this study, we find that factors influencing the success of arthrocentesis include age and oral habits. We also conclude that arthrocentesis is effective in treating mouth opening symptoms and for pain relief. PMID:25247144

  13. Social Factors Influencing Child Health in Ghana

    PubMed Central

    Quansah, Emmanuel; Ohene, Lilian Akorfa; Norman, Linda; Mireku, Michael Osei; Karikari, Thomas K.

    2016-01-01

    Objectives Social factors have profound effects on health. Children are especially vulnerable to social influences, particularly in their early years. Adverse social exposures in childhood can lead to chronic disorders later in life. Here, we sought to identify and evaluate the impact of social factors on child health in Ghana. As Ghana is unlikely to achieve the Millennium Development Goals’ target of reducing child mortality by two-thirds between 1990 and 2015, we deemed it necessary to identify social determinants that might have contributed to the non-realisation of this goal. Methods ScienceDirect, PubMed, MEDLINE via EBSCO and Google Scholar were searched for published articles reporting on the influence of social factors on child health in Ghana. After screening the 98 articles identified, 34 of them that met our inclusion criteria were selected for qualitative review. Results Major social factors influencing child health in the country include maternal education, rural-urban disparities (place of residence), family income (wealth/poverty) and high dependency (multiparousity). These factors are associated with child mortality, nutritional status of children, completion of immunisation programmes, health-seeking behaviour and hygiene practices. Conclusions Several social factors influence child health outcomes in Ghana. Developing more effective responses to these social determinants would require sustainable efforts from all stakeholders including the Government, healthcare providers and families. We recommend the development of interventions that would support families through direct social support initiatives aimed at alleviating poverty and inequality, and indirect approaches targeted at eliminating the dependence of poor health outcomes on social factors. Importantly, the expansion of quality free education interventions to improve would-be-mother’s health knowledge is emphasised. PMID:26745277

  14. Structure and Environment Influence in DNA Conduction

    NASA Technical Reports Server (NTRS)

    Adessi, C.; Walch, S.; Anantram, M. P.; Biegel, Bryan A. (Technical Monitor)

    2002-01-01

    Results for transmission through a poly(G) DNA molecule are presented. We show that a modification of the rise of a B-DNA form can induce a shift of the conduction channel toward the valence one. We clearly prove that deformation of the backbone of the molecule has a significant influence on hole transport. Finally, we observe that the presence of ionic species, such Na, near the molecule can create new conduction channels.

  15. Magnetic field influence on paramecium motility

    SciTech Connect

    Rosen, M.F.; Rosen, A.D. )

    1990-01-01

    The influence of a moderately intense static magnetic field on movement patterns of free swimming Paramecium was studied. When exposed to fields of 0.126 T, these ciliated protozoa exhibited significant reduction in velocity as well as a disorganization of movement pattern. It is suggested that these findings may be explained on the basis of alteration in function of ion specific channels within the cell membrane.

  16. Factors Influencing the Fatigue Strength of Materials

    NASA Technical Reports Server (NTRS)

    Bollenrath, F

    1941-01-01

    A number of factors are considered which influence the static and fatigue strength of materials under practical operating conditions as contrasted with the relations obtaining under conditions of the usual testing procedure. Such factors are interruptions in operation, periodically fluctuating stress limits and mean stresses with periodic succession of several groups and stress states, statistical changes and succession of stress limits and mean stresses, frictional corrosion at junctures, and notch effects.

  17. Providers influence reporting policies, improve financial disclosure.

    PubMed

    Covaleski, M A; Dirsmith, M W

    1985-10-01

    Because of the healthcare provider's increased financial accountability to the public, it is important that healthcare organizations take a more active interest in improving the disclosure policies of their financial activities. To do so, these providers must understand existing reporting requirements, become more actively involved in influencing financial reporting policies, and develop relevant, forward looking information to be communicated to internal groups such as the board of directors and the finance committee. PMID:10273775

  18. Influence of religious belief on Mongolian medicine.

    PubMed

    Caijilahu, C

    1999-04-01

    Religious belief exerts certain influence on early development of Mongolian medicine. Up to early 20th century, some aspects of Mongolian medicine, including diagnostic methods and therapeutic remedies were all dyed with religion. Hence, the study of Mongolian medical history involves culture, philosophy and religious belief, especially culture in its broad sense, and micro - religion, such as the witchery culture of remote ancient time, totem in primitive religion and all kinds of worshipping and beliefs. PMID:11623862

  19. Modeling of Internet Influence on Group Emotion

    NASA Astrophysics Data System (ADS)

    Czaplicka, Agnieszka; Hołyst, Janusz A.

    Long-range interactions are introduced to a two-dimensional model of agents with time-dependent internal variables ei = 0, ±1 corresponding to valencies of agent emotions. Effects of spontaneous emotion emergence and emotional relaxation processes are taken into account. The valence of agent i depends on valencies of its four nearest neighbors but it is also influenced by long-range interactions corresponding to social relations developed for example by Internet contacts to a randomly chosen community. Two types of such interactions are considered. In the first model the community emotional influence depends only on the sign of its temporary emotion. When the coupling parameter approaches a critical value a phase transition takes place and as result for larger coupling constants the mean group emotion of all agents is nonzero over long time periods. In the second model the community influence is proportional to magnitude of community average emotion. The ordered emotional phase was here observed for a narrow set of system parameters.

  20. Natural polyphenols: Influence on membrane transporters

    PubMed Central

    Hussain, Saad Abdulrahman; Sulaiman, Amal Ajaweed; Alhaddad, Hasan; Alhadidi, Qasim

    2016-01-01

    Accumulated evidence has focused on the use of natural polyphenolic compounds as nutraceuticals since they showed a wide range of bioactivities and exhibited protection against variety of age-related disorders. Polyphenols have variable potencies to interact, and hence alter the activities of various transporter proteins, many of them classified as anion transporting polypeptide-binding cassette transporters like multidrug resistance protein and p-glycoprotein. Some of the efflux transporters are, generally, linked with anticancer and antiviral drug resistance; in this context, polyphenols may be beneficial in modulating drug resistance by increasing the efficacy of anticancer and antiviral drugs. In addition, these effects were implicated to explain the influence of dietary polyphenols on drug efficacy as result of food-drug interactions. However, limited data are available about the influence of these components on uptake transporters. Therefore, the objective of this article is to review the potential efficacies of polyphenols in modulating the functional integrity of uptake transporter proteins, including those terminated the effect of neurotransmitters, and their possible influence in neuropharmacology. PMID:27069731

  1. Socially guided attention influences infants' communicative behavior.

    PubMed

    Miller, Jennifer L; Gros-Louis, Julie

    2013-12-01

    For effective prelinguistic communication, infants must be able to direct their attention, vocalizations, and nonverbal gestures in social interactions. The purpose of our study was to examine how different styles of caregiver responses influenced infant attentional and communicative behavior in social interactions, based on prior studies that have shown influences of responsiveness on attention, language and cognitive outcomes. Infants were exposed to redirective and sensitive behavior systematically using an ABA design to examine real-time changes in infants' behavior as a function of caregiver responses. During the two baseline "A" periods, caregivers were instructed to play as they would at home. During the social response "B" period, caregivers were instructed to respond sensitively to infants' behavior on one visit and redirectively on the other visit. Results demonstrated that when caregivers behaved redirectively, infants shifted their attention more frequently and decreased the duration of their visual attention. Caregiver responses also resulted in changes in vocal and gesture production. Infants decreased their production of caregiver-directed vocalizations, gestures, and gesture-vocal combinations during in the redirective condition. Results suggest that caregiver sensitive responding to infants' attentional focus may be one influence on infants' attentional and prelinguistic communicative behavior. PMID:23906941

  2. Understanding How Grammatical Aspect Influences Legal Judgment.

    PubMed

    Sherrill, Andrew M; Eerland, Anita; Zwaan, Rolf A; Magliano, Joseph P

    2015-01-01

    Recent evidence suggests that grammatical aspect can bias how individuals perceive criminal intentionality during discourse comprehension. Given that criminal intentionality is a common criterion for legal definitions (e.g., first-degree murder), the present study explored whether grammatical aspect may also impact legal judgments. In a series of four experiments participants were provided with a legal definition and a description of a crime in which the grammatical aspect of provocation and murder events were manipulated. Participants were asked to make a decision (first- vs. second-degree murder) and then indicate factors that impacted their decision. Findings suggest that legal judgments can be affected by grammatical aspect but the most robust effects were limited to temporal dynamics (i.e., imperfective aspect results in more murder actions than perfective aspect), which may in turn influence other representational systems (i.e., number of murder actions positively predicts perceived intentionality). In addition, findings demonstrate that the influence of grammatical aspect on situation model construction and evaluation is dependent upon the larger linguistic and semantic context. Together, the results suggest grammatical aspect has indirect influences on legal judgments to the extent that variability in aspect changes the features of the situation model that align with criteria for making legal judgments. PMID:26496364

  3. Heavy metals influence on ascorbic acid level

    NASA Astrophysics Data System (ADS)

    Kamaldinov, E. V.; Patrashkov, S. A.; Batenyeva, E. V.; Korotkevich, O. S.

    2003-05-01

    It is well known that heavy metals (HM) are extremely dangerous pollutants influencing to metabolism in animals' organisms. The vitamin C is one of the most important metabolites taking part in many biochemical processes. We studied the influence of main essential HM-Zn and Cu as well as the based supertoxical elements - Cd and Pd on ascorbic acid level in serum. The studies were carried out in Tulinskoe farm of Novosibirsk region. The objects of investigations were piglets (2 month after weaning) and 6-month pigs of Early Ripe Meat breed. The levels of HM in bristle were found by stripping voltammetric analysis using the TA-2 analyzer. Vitamin C content was determined by I.P. Kondrakhin (1985) method using 2,2-dipyridyl. The significant negative correlations between Pb, Cd content and vitamin C (-0.46 ± 0.18, -0.47 ± 0.19) in 6-month pigs were determined. The tendencies of negative correlation between all HM levels in hair and ascorbic acid level in plasma of piglets were revealed. Thus, the obtained correlations let us to suppose that all studied HM influence on 1-gulono-gamma-lactone oxidase and other vitamin C metabolism enzymes activity.

  4. Factors that influence engagement in collaborative practice

    PubMed Central

    Herbert, Carol P.; Bainbridge, Lesley; Bickford, Julia; Baptiste, Susan; Brajtman, Susan; Dryden, Trish; Hall, Pippa; Risdon, Cathy; Solomon, Patricia

    2007-01-01

    OBJECTIVE To generate hypotheses regarding factors that might influence engagement in collaborative practice. DESIGN Qualitative study using in-depth interviews. SETTING Participants interviewed each other in dyads. The pairing was based upon geographical location and proximity to each other. PARTICIPANTS Eight professionals from the disciplines of medicine, nursing, occupational therapy, physical therapy, and massage therapy. METHOD Semistructured interviews, lasting 30 to 45 minutes each, were recorded and transcribed verbatim. The transcripts were read by all research team members using independent content analysis for common words, phrases, statements, or units of text for key themes. At a subsequent face-to-face meeting, the team used an iterative process of comparing and contrasting key themes until consensus was reached. The transcripts were then analyzed further for subthemes using NVivo software. MAIN FINDINGS Initial findings suggest that some common characteristics grounded in family history, school experiences, social interactions, and professional training might influence collaborative practice choices. The narrative form of the interview broke down interpersonal and interprofessional barriers, creating a new level of trust and respect that could improve professional collaboration. CONCLUSION This study suggests that life experiences from childhood into later adulthood can and do influence professional choices. PMID:17872847

  5. Affective and motivational influences in person perception.

    PubMed

    Kuzmanovic, Bojana; Jefferson, Anneli; Bente, Gary; Vogeley, Kai

    2013-01-01

    Interpersonal impression formation is highly consequential for social interactions in private and public domains. These perceptions of others rely on different sources of information and processing mechanisms, all of which have been investigated in independent research fields. In social psychology, inferences about states and traits of others as well as activations of semantic categories and corresponding stereotypes have attracted great interest. On the other hand, research on emotion and reward demonstrated affective and motivational influences of social cues on the observer, which in turn modulate attention, categorization, evaluation, and decision processes. While inferential and categorical social processes have been shown to recruit a network of cortical brain regions associated with mentalizing and evaluation, the affective influence of social cues has been linked to subcortical areas that play a central role in detection of salient sensory input and reward processing. In order to extend existing integrative approaches to person perception, both the inferential-categorical processing of information about others, and affective and motivational influences of this information on the beholder should be taken into account. PMID:23781188

  6. Influences on Neighborhood Walking in Older Adults

    PubMed Central

    Gallagher, Nancy Ambrose; Clarke, Philippa J.; Ronis, David L.; Cherry, Carol Loveland; Nyquist, Linda; Gretebeck, Kimberlee A.

    2014-01-01

    The purpose of this cross-sectional survey study was to examine the influence of self-efficacy, outcome expectations and environment on neighborhood walking in older adults with (n=163, mean age=78.7, SD=7.96 years) and without (n=163, mean age=73.6, SD=7.93 years) mobility limitations (controlling for demographic characteristics). Measures included: Neighborhood Physical Activity Questionnaire, Multidimensional Outcome Expectations for Exercise Scale, Neighborhood Environment Walkability Scale, and self-efficacy scales. Multiple regression revealed that in mobility-limited older adults, demographic characteristics, self-efficacy, and outcome expectations explained 17.4% of variance in neighborhood walking, while environment (neighborhood destinations and design) explained 9.5%. Destinations, self-efficacy, gender, and outcome expectations influenced walking. In those without mobility limitations, demographic characteristics, self-efficacy, and outcome expectations explained 15.6% of the variance, while environment explained 5.7%. Self-efficacy, gender, and design influenced walking. Neighborhood walking interventions for older adults should include self-efficacy strategies tailored to mobility status and neighborhood characteristics. PMID:22998660

  7. Influences on meat consumption in Australia.

    PubMed

    Lea, E; Worsley, A

    2001-04-01

    In a study of influences on meat consumption, over 700 South Australians answered questions on frequency of meat consumption, beliefs about meat and nutrition, perceived difficulties with and benefits of vegetarian diets, personal values, number of vegetarian significant others, use in and trust of health/nutrition/food information sources, and demography. Perceived difficulties with vegetarian diets, the number of vegetarian significant others and beliefs about meat were important predictors of meat consumption. There were differences between men and women and members of different age groups, which should be taken into account when attempts are made to influence meat consumption. For example, health promotion campaigns that focus on whether or not meat is necessary in the diet may influence meat consumption, but would be most successful if directed predominantly at older people and men. In contrast, the meat consumption of women and younger people was strongly associated with more specific concerns about lack of iron and protein in the vegetarian diet. Some of the difficulties people find with vegetarian diets will also apply to plant-based diets generally, and such diets are becoming more widely acknowledged as providing health benefits. Therefore, the findings have important implications for public health. PMID:11237348

  8. Modeling social influences on human health.

    PubMed

    Karelina, Kate; DeVries, A Courtney

    2011-01-01

    Social interactions have long-term physiological, psychological, and behavioral consequences. Social isolation is a well-recognized but little understood risk factor and prognostic marker of disease; it can have profoundly detrimental effects on both mental and physical well-being, particularly during states of compromised health. In contrast, the health benefits associated with social support (both reduced risk and improved recovery) are evident in a variety of illnesses and injury states; however, the mechanisms by which social interactions influence disease pathogenesis remain largely unidentified. The substantial health impact of the psychosocial environment can occur independently of traditional disease risk factors and is not accounted for solely by peer-encouraged development of health behaviors. Instead, social interactions are capable of altering shared pathophysiological mechanisms of multiple disease states in distinct measurable ways. Converging evidence from animal models of injury and disease recapitulates the physiological benefits of affiliative social interactions and establishes several endogenous mechanisms (inflammatory signals, glucocorticoids, and oxytocin) by which social interactions influence health outcomes. Taken together, both clinical and animal research are undoubtedly necessary to develop a complete mechanistic understanding of social influences on health. PMID:21097660

  9. Early environment influences later performance in fishes.

    PubMed

    Jonsson, B; Jonsson, N

    2014-08-01

    Conditions fish encounter during embryogenesis and early life history can leave lasting effects not only on morphology, but also on growth rate, life-history and behavioural traits. The ecology of offspring can be affected by conditions experienced by their parents and mother in particular. This review summarizes such early impacts and their ecological influences for a variety of teleost species, but with special reference to salmonids. Growth and adult body size, sex ratio, egg size, lifespan and tendency to migrate can all be affected by early influences. Mechanisms behind such phenotypically plastic impacts are not well known, but epigenetic change appears to be one central mechanism. The thermal regime during development and incubation is particularly important, but also early food consumption and intraspecific density can all be responsible for later life-history variation. For behavioural traits, early experiences with effects on brain, sensory development and cognition appear essential. This may also influence boldness and other social behaviours such as mate choice. At the end of the review, several issues and questions for future studies are given. PMID:24961386

  10. Natural polyphenols: Influence on membrane transporters.

    PubMed

    Hussain, Saad Abdulrahman; Sulaiman, Amal Ajaweed; Alhaddad, Hasan; Alhadidi, Qasim

    2016-01-01

    Accumulated evidence has focused on the use of natural polyphenolic compounds as nutraceuticals since they showed a wide range of bioactivities and exhibited protection against variety of age-related disorders. Polyphenols have variable potencies to interact, and hence alter the activities of various transporter proteins, many of them classified as anion transporting polypeptide-binding cassette transporters like multidrug resistance protein and p-glycoprotein. Some of the efflux transporters are, generally, linked with anticancer and antiviral drug resistance; in this context, polyphenols may be beneficial in modulating drug resistance by increasing the efficacy of anticancer and antiviral drugs. In addition, these effects were implicated to explain the influence of dietary polyphenols on drug efficacy as result of food-drug interactions. However, limited data are available about the influence of these components on uptake transporters. Therefore, the objective of this article is to review the potential efficacies of polyphenols in modulating the functional integrity of uptake transporter proteins, including those terminated the effect of neurotransmitters, and their possible influence in neuropharmacology. PMID:27069731

  11. Influence of blood coagulability after spinal surgeries

    PubMed Central

    Matsumoto, Marcelo Hide; Rodrigues, Luiz Claudio Lacerda; Batalini, Luiz Gustavo da silva; Fonteles, Thales Arcanjo; Bortoletto, Adalberto

    2014-01-01

    Objective: To verify whether spinal surgery causes relevant changes in the blood clotting process and define which factors have the greatest influence on changes found. Method: This is a not randomized, cross-sectional study, Forty seven patients were evaluated between August 2011 and February 2013, whose clinical, surgical, laboratory and image daata were collected. The data obtained were crossed with the epidemiological data of each patient in a moment prior to and another after surgery searching which variables have been directly influenced. Result: Our analysis showed that the most important changes occurred in patients with BMI classified, according to the World Health Organization (WHO) as out of healthy range. Other smaller correlations were also found. Another important consideration was the tendency to observe hypercoagulability in smoker patients, a fact that is not influenced by spinal procedures. Conclusion: We concluded that spinal surgeries cause few relevant changes in the blood clotting process and that among the factors studied, BMI (when out of the healthy range, according to the WHO classification) showed closer relationship with changes in laboratory coagulation tests. Level of Evidence III, Cross-Sectional Study. PMID:25328429

  12. Understanding How Grammatical Aspect Influences Legal Judgment

    PubMed Central

    Sherrill, Andrew M.; Eerland, Anita; Zwaan, Rolf A.; Magliano, Joseph P.

    2015-01-01

    Recent evidence suggests that grammatical aspect can bias how individuals perceive criminal intentionality during discourse comprehension. Given that criminal intentionality is a common criterion for legal definitions (e.g., first-degree murder), the present study explored whether grammatical aspect may also impact legal judgments. In a series of four experiments participants were provided with a legal definition and a description of a crime in which the grammatical aspect of provocation and murder events were manipulated. Participants were asked to make a decision (first- vs. second-degree murder) and then indicate factors that impacted their decision. Findings suggest that legal judgments can be affected by grammatical aspect but the most robust effects were limited to temporal dynamics (i.e., imperfective aspect results in more murder actions than perfective aspect), which may in turn influence other representational systems (i.e., number of murder actions positively predicts perceived intentionality). In addition, findings demonstrate that the influence of grammatical aspect on situation model construction and evaluation is dependent upon the larger linguistic and semantic context. Together, the results suggest grammatical aspect has indirect influences on legal judgments to the extent that variability in aspect changes the features of the situation model that align with criteria for making legal judgments. PMID:26496364

  13. Factors influencing internal color of cooked meats.

    PubMed

    Suman, Surendranath P; Nair, Mahesh N; Joseph, Poulson; Hunt, Melvin C

    2016-10-01

    This manuscript overviews the pertinent research on internal color of uncured cooked meats, biochemical processes involved in meat cookery, and fundamental mechanisms governing myoglobin thermal stability. Heat-induced denaturation of myoglobin, responsible for the characteristic dull-brown color of cooked meats, is influenced by a multitude of endogenous (i.e., pH, muscle source, species, redox state) and exogenous (i.e., packaging, ingredients, storage) factors. The interactions between these factors critically influence the internal cooked color and can confuse the consumers, who often perceive cooked color to be a reliable indicator for doneness and safety. While certain phenomena in cooked meat color are cosmetic in nature, others can mislead consumers and result in foodborne illnesses. Research in meat color suggests that processing technologies and cooking practices in industry as well as households influence the internal cooked color. Additionally, the guidelines of many international public health and regulatory authorities recommend using meat thermometers to determine safe cooking endpoint temperature and to ensure product safety. PMID:27131513

  14. Understanding Influence within the Context of Nursing: Development of the Adams Influence Model Using Practice, Research, and Theory.

    PubMed

    Adams, Jeffrey M; Natarajan, Sudha

    2016-01-01

    Acquiring influence, and knowing how to use it, is a required competency for nurse leaders, yet the concept of influence and how it works is not well described in the nursing literature. In this article, the authors examine what is known about influence and present an influence model specific to nurse leaders. The Adams Influence Model was developed through an iterative process and is based on a comprehensive review of the influence literature, expert commentary, multiple pilot studies, evaluation of nursing theories, and validation by an external data source. Rather than defining "how to" influence, the model serves as a guide for personal reflection, helping nurse leaders understand and reflect on the influence process and factors, tactics, and strategies they can use when seeking to influence others. PMID:27490886

  15. Nutrient environment influences competition among Aspergillus flavus genotypes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Structures of Aspergillus flavus populations, shaped by intraspecific competition, influence the incidences and severities of crop aflatoxin contamination. Competition for nutrients may be one factor modulating intraspecific interactions, but influences of specific types and concentrations of nutrie...

  16. Meteorological influences on mass accountability of aerially applied sprays

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The deposition and drift of aerially applied crop protection materials is influenced by a number of factors including equpment setup and operational parameters, spray material characteristics, and meteorological effects. This work examines the meteorological influences that effect the ultimate fate...

  17. INFLUENCE OF PROTOZOAN GRAZING ON CONTAMINANT BIODEGRADATION. (R825418)

    EPA Science Inventory

    The influence of protozoan grazing on biodegradation rates in samples from contaminated aquifer sediment was evaluated under aerobic and anaerobic conditions. Predator¯prey biomass ratios suggested that protozoan grazing might be influencing bacterial populations....

  18. A Survey of Models and Algorithms for Social Influence Analysis

    NASA Astrophysics Data System (ADS)

    Sun, Jimeng; Tang, Jie

    Social influence is the behavioral change of a person because of the perceived relationship with other people, organizations and society in general. Social influence has been a widely accepted phenomenon in social networks for decades. Many applications have been built based around the implicit notation of social influence between people, such as marketing, advertisement and recommendations. With the exponential growth of online social network services such as Facebook and Twitter, social influence can for the first time be measured over a large population. In this chapter, we survey the research on social influence analysis with a focus on the computational aspects. First, we present statistical measurements related to social influence. Second, we describe the literature on social similarity and influences. Third, we present the research on social influence maximization which has many practical applications including marketing and advertisement.

  19. Influence diagrams as oil spill decision science tools

    EPA Science Inventory

    Making inferences on risks to ecosystem services (ES) from ecological crises can be more reliably handled using decision science tools. Influence diagrams (IDs) are probabilistic networks that explicitly represent the decisions related to a problem and evidence of their influence...

  20. 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. PMID:26412096

  1. Microsphere size influences the foreign body reaction.

    PubMed

    Zandstra, J; Hiemstra, C; Petersen, A H; Zuidema, J; van Beuge, M M; Rodriguez, S; Lathuile, A A; Veldhuis, G J; Steendam, R; Bank, R A; Popa, E R

    2014-01-01

    Biodegradable poly-(DL-lactide-co-glycolide) (PLGA) microspheres (MSP) are attractive candidate vehicles for site-specific or systemic sustained release of therapeutic compounds. This release may be altered by the host's foreign body reaction (FBR), which is dependent on the characteristics of the implant, e.g. chemistry, shape or size. In this study, we focused on the characterisation of the influence of MSP size on the FBR. To this end we injected monodisperse MSP of defined size (small 5.8 µm, coefficient of variance (CV) 14 % and large 29.8 µm, CV 4 %) and polydisperse MSP (average diameter 34.1 µm, CV 51 %) under the skin of rats. MSP implants were retrieved at day 7, 14 and 28 after transplantation. The FBR was studied in terms of macrophage infiltration, implant encapsulation, vascularisation and extracellular matrix deposition. Although PLGA MSP of all different sizes demonstrated excellent in vitro and in vivo biocompatibility, significant differences were found in the characteristics of the FBR. Small MSP were phagocytosed, while large MSP were not. Large MSP occasionally elicited giant cell formation, which was not observed after implantation of small MSP. Cellular and macrophage influx and collagen deposition were increased in small MSP implants compared to large MSP. We conclude that the MSP size influences the FBR and thus might influence clinical outcome when using MSP as a drug delivery device. We propose that a rational choice of MSP size can aid in optimising the therapeutic efficacy of microsphere-based therapies in vivo. PMID:25350249

  2. Dynamic influences of changing gear tooth stiffness

    SciTech Connect

    Morguel, O.K.; Esat, I.

    1997-07-01

    One of the principal sources of vibratory excitation of gear a system is due to the angular speed fluctuation of meshing gears due to non-linearities and profile errors and tooth and supporting bearings flexibility. The transmission error is also influenced by the varying force at the contact point of the meshing gear teeth. The varying contact force itself is influenced by the varying tooth stiffness due to change of orientation of teeth relative to each other, during the contact phase of each pair. This paper presents a simplified single degree of freedom gear system. It is assumed that one member of the gear pair is rigid and flexibility of the gear tooth is attributed only to one section of the gear system. This enables the equation to be simplified to a single degree of freedom system. The resulting non-linear equation is solved iteratively by employing a method which combines piecewise linearization for the stiffness and resulting contact orientation shift due to shaft and tooth flexibility. The contact shift will be referred as the phase shift in this report. The early finding indicates that there are significant differences between the response of the system incorporating three different tooth stiffness, namely, constant tooth stiffness, rectangular wave tooth stiffness and sinusoidal tooth stiffness. The results also implies that any design specification associated with gears has to include gear tooth influences, especially if the excitation is of a major concern. The rectangular stiffness variation which most accurately describes the tooth stiffness gives a response fluctuation, studied in the frequency domain shows that the effective natural frequencies fluctuates between certain upper and lower limits. Thus the paper suggest that any design study should consider these limits.

  3. Influence of plasticizer on soft polymer gelation.

    PubMed

    Jones, D W; Sutow, E J; Graham, B S; Milne, E L; Johnston, D E

    1986-05-01

    An evaluation has been made of the soft polymer gel systems of the type used as prosthodontic short-term denture-lining materials. The purpose of the study was to determine the effect upon gel strength and gelation time produced by variations in the composition of the plasticizer liquids. Poly(ethylmethacrylate) co-polymers were mixed with combinations of ethyl alcohol and the esters dibutyl phthalate (DBP), butylphthalyl butylglycolate (BPBG), and benzyl salicylate (BS). The relative rate of gelation of plasticizer polymer compositions was obtained by means of a reciprocating rheometer. The gelation rate was found to increase rapidly with an increase in the ethyl alcohol content. Significantly shorter gelation times were also found with liquids containing the lower-molecular-weight esters. A linear relationship was found between the ethyl alcohol content and the log of the gelation time. The higher-molecular-weight esters produced the strongest gel. A linear relationship was found between the gelation (log) times and the seven-day puncture strength. The ratio of polymer to plasticizer liquid was found to have a very significant influence upon the puncture strength and gelation time. Molecular weight or molecular volume of the ester plasticizers was found to have a greater influence on gel formation than the cohesive energy parameter. The strong polar bonding of ethyl alcohol was found to have a significant influence on both the rate of gel formation and the subsequent gel strength. The data indicate that controlled variations in the characteristics of plasticity and gel strength of dental soft polymer systems can be made to suit different clinical prosthodontic requirements. PMID:3457816

  4. Influence of ENSO on coastal flood hazard

    NASA Astrophysics Data System (ADS)

    Muis, Sanne; Haigh, Ivan; Veldkamp, Ted; Aerts, Jeroen; Ward, Philip

    2016-04-01

    ENSO is the most dominant interannual signal of climate variability. While ENSO-induced climate anomalies may result in changed probabilities of coastal flooding, little is known about how interannual variability affects the occurrence of extreme sea levels, and the probability of coastal flooding around the world. With this contribution, we will show in which areas El Niño or La Niña can result in significantly higher/lower extreme sea levels than during neutral years, and how this influences flood hazard. To assess this, we developed a model framework to assess the influences of the El Niño Southern Oscillation (ENSO) on coastal flood hazard at the global-scale. This approach is based on a new dynamically-derived global dataset that contains sea levels along the entire world's coastline for 1979-2014 (GTSR dataset). However, the modelled sea level variations in GTSR are strictly due to gravitational tides and barotropic changes (changes in wind and pressure): baroclinic effects (density differences) are not considered. Subsequently, we used satellite altimetry data and ocean reanalysis data to reconstruct the interannual signal in mean sea level, and combined this with the GTSR sea level timeseries. Using this timeseries we calculated the anomalies in sea level extremes during El Niño years and La Niña years (compared to all years) and we assess the correlation between the sea level extremes and ENSO driven variability. In this contribution, we show our first results on the influence of ENSO on coastal flood hazard around the world, and we discuss potential applications in, for example, disaster planning.

  5. Does climate directly influence NPP globally?

    PubMed

    Chu, Chengjin; Bartlett, Megan; Wang, Youshi; He, Fangliang; Weiner, Jacob; Chave, Jérôme; Sack, Lawren

    2016-01-01

    The need for rigorous analyses of climate impacts has never been more crucial. Current textbooks state that climate directly influences ecosystem annual net primary productivity (NPP), emphasizing the urgent need to monitor the impacts of climate change. A recent paper challenged this consensus, arguing, based on an analysis of NPP for 1247 woody plant communities across global climate gradients, that temperature and precipitation have negligible direct effects on NPP and only perhaps have indirect effects by constraining total stand biomass (Mtot ) and stand age (a). The authors of that study concluded that the length of the growing season (lgs ) might have a minor influence on NPP, an effect they considered not to be directly related to climate. In this article, we describe flaws that affected that study's conclusions and present novel analyses to disentangle the effects of stand variables and climate in determining NPP. We re-analyzed the same database to partition the direct and indirect effects of climate on NPP, using three approaches: maximum-likelihood model selection, independent-effects analysis, and structural equation modeling. These new analyses showed that about half of the global variation in NPP could be explained by Mtot combined with climate variables and supported strong and direct influences of climate independently of Mtot , both for NPP and for net biomass change averaged across the known lifetime of the stands (ABC = average biomass change). We show that lgs is an important climate variable, intrinsically correlated with, and contributing to mean annual temperature and precipitation (Tann and Pann ), all important climatic drivers of NPP. Our analyses provide guidance for statistical and mechanistic analyses of climate drivers of ecosystem processes for predictive modeling and provide novel evidence supporting the strong, direct role of climate in determining vegetation productivity at the global scale. PMID:26442433

  6. Factors influencing variation in dentist service rates.

    PubMed

    Grembowski, D; Milgrom, P; Fiset, L

    1990-01-01

    In the previous article, we calculated dentist service rates for 200 general dentists based on a homogeneous, well-educated, upper-middle-class population of patients. Wide variations in the rates were detected. In this analysis, factors influencing variation in the rates were identified. Variation in rates for categories of dental services was explained by practice characteristics, patient exposure to fluoridated water supplies, and non-price competition in the dental market. Rates were greatest in large, busy practices in markets with high fees. Older practices consistently had lower rates across services. As a whole, these variables explained between 5 and 30 percent of the variation in the rates. PMID:2118182

  7. The uses (and abuses) of influence.

    PubMed

    Cialdini, Robert; Cliffe, Sarah

    2013-01-01

    The ability to persuade others to contribute to your efforts is a key skill for managers, for team members--for anyone who wants to elevate the probability of success. Research by leading social scientist Robert Cialdini has found that persuasion works by appealing to certain deeply rooted human responses: liking, reciprocity, social proof, commitment and consistency, authority, and scarcity. In this edited interview with HBR's executive editor, Cialdini expands on the six principles of persuasion and how leaders can make effective, authentic use of them in everyday business situations. He also previews findings from new research on the ethics of influence and how dishonesty affects individuals and the organization. PMID:24730172

  8. Detection and control of microbiologically influenced corrosion

    SciTech Connect

    Licina, G.J. )

    1990-01-01

    The Sourcebook for Microbiologically Influenced Corrosion in Nuclear Power Plants (EPRI NP-5580) introduced many nuclear plant personnel to the mechanisms of MIC, provided a glossary of pertinent terms and a listing of organisms that have been associated with MIC, and gave examples of MIC from nuclear plant systems via fifteen case histories. Methods for the diagnosis, prevention, and control of existing MIC conditions were also provided. This report expands upon the background given in EPRI NP-5580 and provides updated information on field experience with various prevention, mitigation, repair, and replacement methods. Guidelines for replacement are also provided in the event that a MCI condition cannot been prevented or controlled.

  9. Dust density influence on complex plasma decay

    SciTech Connect

    Coueedel, L.; Mikikian, M.; Boufendi, L.

    2008-09-07

    In this paper, the influence of dust particles on the plasma losses in a complex plasma afterglow is studied. It is shown that the dust particles can drastically shorten the plasma loss time by absorption-recombination onto their surfaces. The dust particle absorption frequency increases with the dust density but the dependence is not linear for high dust density. Finally, the possible use of dust absorption frequency measurements as a diagnostics for complex plasmas is mentioned and supported by comparison to existing experimental data.

  10. The Influence of Microgravity on Plants

    NASA Technical Reports Server (NTRS)

    Levine, Howard G.

    2010-01-01

    This slide presentation reviews the studies and the use of plants in various space exploration scenarios. The current state of research on plant growth in microgravity is reviewed, with several questions that require research for answers to assist in our fundamental understanding of the influence of microgravity and the space environment on plant growth. These questions are posed to future Principal Investigators and Payload Developers, attending the meeting, in part, to inform them of NASA's interest in proposals for research on the International Space Station.

  11. Social Influence and the Autism Epidemic1

    PubMed Central

    Liu, Ka-Yuet; King, Marissa; Bearman, Peter S.

    2010-01-01

    Despite a plethora of studies, we do not know why autism incidence has increased rapidly over the past two decades. Using California data, this study shows that children living very close to a child previously diagnosed with autism are more likely to be diagnosed with autism. An underlying social influence mechanism involving information diffusion drives this result, contributing to 16% of the increase in prevalence over 2000–2005. We eliminate competing explanations (i.e., residential sorting, environmental toxicants, and viral transmission) through seven tests and show that information diffusion simultaneously contributed to the increased prevalence, spatial clustering, and decreasing age of diagnosis. PMID:20503647

  12. Recognizing dynamic scenes: influence of processing orientation.

    PubMed

    Huff, Markus; Schwan, Stephan; Garsoffky, Bärbel

    2011-04-01

    From face recognition studies, it is known that instructions are able to change processing orientation of stimuli, leading to an impairment of recognition performance. The present study examined instructional influences on the visual recognition of dynamic scenes. A global processing orientation without any instruction was assumed to lead to highest recognition performance, whereas instructions focusing participants' attention on certain characteristics of the event should lead to a local processing orientation with an impairment of visual recognition performance as a direct consequence. Since the pattern of results provided evidence for this hypothesis, theoretical contributions were discussed. PMID:21667754

  13. Influence of corrosion layers on quantitative analysis

    NASA Astrophysics Data System (ADS)

    Denker, A.; Bohne, W.; Opitz-Coutureau, J.; Rauschenberg, J.; Röhrich, J.; Strub, E.

    2005-09-01

    Art historians and restorers in charge of ancient metal objects are often reluctant to remove the corrosion layer evolved over time, as this would change the appearance of the artefact dramatically. Therefore, when an elemental analysis of the objects is required, this has to be done by penetrating the corrosion layer. In this work the influence of corrosion was studied on Chinese and Roman coins, where removal of oxidized material was possible. Measurements on spots with and without corrosion are presented and the results discussed.

  14. Task motivation influences alpha suppression following errors.

    PubMed

    Compton, Rebecca J; Bissey, Bryn; Worby-Selim, Sharoda

    2014-07-01

    The goal of the present research is to examine the influence of motivation on a novel error-related neural marker, error-related alpha suppression (ERAS). Participants completed an attentionally demanding flanker task under conditions that emphasized either speed or accuracy or under conditions that manipulated the monetary value of errors. Conditions in which errors had greater motivational value produced greater ERAS, that is, greater alpha suppression following errors compared to correct trials. A second study found that a manipulation of task difficulty did not affect ERAS. Together, the results confirm that ERAS is both a robust phenomenon and one that is sensitive to motivational factors. PMID:24673621

  15. Factors influencing aircraft ground handling performance

    NASA Technical Reports Server (NTRS)

    Yager, T. J.

    1983-01-01

    Problems associated with aircraft ground handling operations on wet runways are discussed and major factors which influence tire/runway braking and cornering traction capability are identified including runway characteristics, tire hydroplaning, brake system anomalies, and pilot inputs. Research results from tests with instrumented ground vehicles and aircraft, and aircraft wet runway accident investigation are summarized to indicate the effects of different aircraft, tire, and runway parameters. Several promising means are described for improving tire/runway water drainage capability, brake system efficiency, and pilot training to help optimize aircraft traction performance on wet runways.

  16. Being influenced: a Cherokee way of mentoring.

    PubMed

    Lowe, John

    2005-01-01

    This article reports research findings related to how the Cherokee male achieves self-reliance and how health care professionals can facilitate and incorporate the Cherokee concept of self-reliance into heath care of the Cherokee. Self-reliance to the Cherokee has been defined as a cultural domain with a composite of the three categories: (a) being responsible, (b) being disciplined, and (c) being confident (Lowe, 2002, 2003). Two sample groups of 12 to 14 Cherokee adults were interviewed and observed. The results reveal that mentor-type relationships influenced the participants in the development of Cherokee self-reliance. PMID:16028448

  17. Atmospheric chemistry - Response to human influence

    NASA Technical Reports Server (NTRS)

    Logan, J. A.; Prather, M. J.; Wofsy, S. G.; Mcelroy, M. B.

    1978-01-01

    Global atmospheric chemistry is surveyed, and the agreement of models with observed distribution of gases is considered. The influence of human perturbations due to combustion, agriculture, and chloro-carbon releases is examined with emphasis on ozone. Effects of combustion-related releases of CO on the abundances of other gases as well as possible effects of CO on tropospheric ozone are discussed. Other topics include the contribution of the chlorocarbon industry to stratospheric chloride and the recombination of nitrogen fixed by agriculture and combustion.

  18. Influence of Disorder on DNA Conductance

    NASA Technical Reports Server (NTRS)

    Adessi, Christophe; Anantram, M. P.; Biegel, Bryan A. (Technical Monitor)

    2003-01-01

    Disorder along a DNA strand due to non uniformity associated with the counter ion type and location, and in rise and twist are investigated using density functional theory. We then model the conductance through a poly(G) DNA strand by including the influence of disorder. We show that the conductance drops by a few orders of magnitude between typical lengths of 10 and 100 nm. Such a decrease occurs with on-site potential disorder that is larger than 100 meV.

  19. Psychopathic Traits Moderate Peer Influence on Adolescent Delinquency

    ERIC Educational Resources Information Center

    Kerr, Margaret; Van Zalk, Maarten; Stattin, Hakan

    2012-01-01

    Background: Peer influence on adolescent delinquency is well established, but little is known about moderators of peer influence. In this study, we examined adolescents' (targets) and their peers' psychopathic personality traits as moderators of peer influence on delinquency in peer networks. We used three separate dimensions of the psychopathic…

  20. Development and Validation of the Family Influence Scale

    ERIC Educational Resources Information Center

    Fouad, Nadya A.; Cotter, Elizabeth W.; Fitzpatrick, Mary E.; Kantamneni, Neeta; Carter, Laura; Bernfeld, Steve

    2010-01-01

    This article describes the development and validation of the Family Influence Scale (FIS). The FIS is designed to assess perceptions of how one's family of origin influences career and work choices. The purpose of Study 1 was to identify the domains of family influence. A 57-item scale was completed by a sample of 205 college students. Results…

  1. Perceived Symbols of Authority and Their Influence on Conformity.

    ERIC Educational Resources Information Center

    Bushman, Brad J.

    Although there are many variables that influence conformity, Bickman (1974) found that the apparel of the person making a request had a significant influence on conformity. To evaluate other factorswhicn may influence conformity (gender, age, status of the conforming subject, and altruism in conforming), 150 adult pedestrians (45% female, 71%…

  2. FAMILY ENVIRONMENTAL INFLUENCES ON CHILDREN’S EATING BEHAVIOR

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Parents can influence children’s dietary behaviors within the home family environment. This presentation will review current research identifying family environmental influences on eating, and how these influences can be used in targeted interventions. For example, the foods available in both home a...

  3. Factors and Influences on High School Student's Career Choices.

    ERIC Educational Resources Information Center

    Dick, Thomas P.; Rallis, Sharon F.

    1991-01-01

    A survey (n=2213) of high school seniors from nine Rhode Island schools studied their academic and career choices related to science and engineering and the perceived influences on those choices. Gender differences are discussed for the influences of parents, pay, interest, and teachers, with the latter potentially influencing career choices of…

  4. The Influence of Alcohol Advertising on Students' Drinking Behaviors.

    ERIC Educational Resources Information Center

    Pedersen, Peggy J.

    2002-01-01

    Examines the perceived influence of alcohol advertising in a daily campus newspaper on the drinking behaviors of students. Findings indicated that college students do perceive that their drinking patterns are influenced by alcohol promotions in the campus newspaper and, furthermore, that self-identified binge drinkers were influenced significantly…

  5. Tracing the Pathways of Evaluation Influence: From Theory to Practice

    ERIC Educational Resources Information Center

    Banuelos, Noelle Vargas

    2012-01-01

    This study sought to explore the ways that evaluation influenced changes in attitudes and actions at the individual and interpersonal levels and the pathways through which this influence occurred, all in a real-world evaluation context. Specifically, Mark & Henry's (2004) proposed model of evaluation influence was used as the framework…

  6. Peer Group Influence on Educational Outcomes: A Quantitative Synthesis.

    ERIC Educational Resources Information Center

    Ide, Judith K.; And Others

    1981-01-01

    A research synthesis of the influence of peer groups on elementary and high school students' achievement and educational/occupational aspirations is presented. Strength of the peer influence-outcome relationship was higher in urban settings and when peer influence was determined by individuals reporting achievement levels of their best friends.…

  7. Friends: The Role of Peer Influence across Adolescent Risk Behaviors.

    ERIC Educational Resources Information Center

    Maxwell, Kimberly A.

    2002-01-01

    Examined peer influence for 1,969 adolescents across 5 risk behaviors: smoking, alcohol consumption, marijuana use, tobacco chewing, and sexual debut. Results show that a random same-sex peer predicts a teen's risk behavior initiation through influence to initiate cigarette and marijuana use, and influence to initiate and stop alcohol and chewing…

  8. Perceived District-Level Leadership Influences upon Student Achievement

    ERIC Educational Resources Information Center

    Mart, Daniel T.

    2011-01-01

    The purpose of this study was to understand district-level leadership's perceived influences on and barriers to improved student achievement. The following research questions were addressed: (a) How do superintendents view their influence on student achievement? (b) How do school board presidents view their influence on student achievement? (c)…

  9. Gratitude to an Unknown Mentor: Bostrom's Influence on Janusik

    ERIC Educational Resources Information Center

    Janusik, Laura A.

    2013-01-01

    Many people influence us throughout our lives, and sometimes we are fortunate enough to have the opportunity to reflect upon the influence. Often, this is more challenging than it sounds, as some people become a part of our DNA, inextricably linked to who we are, what we believe, and how we work. Such is the case of the influence of Robert (Bob)…

  10. Climate Influence on Deep Sea Populations

    PubMed Central

    Company, Joan B.; Puig, Pere; Sardà, Francesc; Palanques, Albert; Latasa, Mikel; Scharek, Renate

    2008-01-01

    Dynamics of biological processes on the deep-sea floor are traditionally thought to be controlled by vertical sinking of particles from the euphotic zone at a seasonal scale. However, little is known about the influence of lateral particle transport from continental margins to deep-sea ecosystems. To address this question, we report here how the formation of dense shelf waters and their subsequent downslope cascade, a climate induced phenomenon, affects the population of the deep-sea shrimp Aristeus antennatus. We found evidence that strong currents associated with intense cascading events correlates with the disappearance of this species from its fishing grounds, producing a temporary fishery collapse. Despite this initial negative effect, landings increase between 3 and 5 years after these major events, preceded by an increase of juveniles. The transport of particulate organic matter associated with cascading appears to enhance the recruitment of this deep-sea living resource, apparently mitigating the general trend of overexploitation. Because cascade of dense water from continental shelves is a global phenomenon, we anticipate that its influence on deep-sea ecosystems and fisheries worldwide should be larger than previously thought. PMID:18197243

  11. Metacognition influences item-method directed forgetting.

    PubMed

    Foster, Nathaniel L; Sahakyan, Lili

    2012-09-01

    In 4 experiments, we examined whether metacognitive beliefs about item memorability influence item-method directed forgetting. In Experiment 1, participants studied loud and quiet items, which were subsequently cued as to-be-remembered (TBR) or to-be-forgotten (TBF). Typically, the volume of stimuli does not influence recall, although loud items are judged as more memorable than quiet items (Rhodes & Castel, 2009). In contrast, we found a recall advantage for loud items in directed forgetting, although this was observed for TBR items but not TBF items. The loud item advantage disappeared in Experiment 2, when we eliminated all TBF trials and instead inserted additional trials during which participants could engage in extra rehearsal of earlier presented items. In Experiments 3 and 4, a recall advantage for loud items was observed again when items were assigned a mixture of positive and negative values, but it did not emerge when items were assigned graded positive values. Overall, the results showed that the recall advantage for loud items emerges only in response to the need to forget some items. We propose 2 mechanisms to account for these results-either participants select to rehearse loud items as a controlled strategy that allows them to forget some items, or they have an unconscious preference for loud items that emerges only in response to the need to forget. PMID:22468801

  12. Geometrical influences on neoclassical magnetohydrodynamic tearing modes

    NASA Astrophysics Data System (ADS)

    Kruger, S. E.; Hegna, C. C.; Callen, J. D.

    1998-02-01

    The influence of geometry on the pressure drives of nonideal magnetohydrodynamic tearing modes is presented. In order to study the effects of elongation, triangularity, and aspect ratio, three different machines are considered to provide a range of tokamak configurations: Tokamak Fusion Test Reactor (circular) [Fusion Technol. 21, 1324 (1992)], DIII-D (D-shaped) [Plasma Physics and Controlled Nuclear Fusion Research 1986 (International Atomic Energy Agency, Vienna, 1987), Vol. 1, p. 159], and Pegasus (extremely low aspect ratio) [Fonck et al., Bull. Am. Phys. Soc. 41, 1400 (1996)]. For large aspect ratio tokamaks, shaping does very little to influence the pressure gradient drives, while at low aspect ratios, a very strong sensitivity to the profiles is found. In particular, this sensitivity is connected to the strong dependence on the magnetic shear. This suggests that at low aspect ratio it may be possible to stabilize neoclassical tearing modes by a flattening the q profile near low order rational surfaces (e.g., q=2/1) using a combination of shaping and localized current drive, whereas at large aspect ratio it is more difficult.

  13. Age Differences in Resistance to Peer Influence

    PubMed Central

    Steinberg, Laurence; Monahan, Kathryn C.

    2009-01-01

    Prior research describes the development of susceptibility to peer pressure in adolescence as following an inverted U-shaped curve, increasing during early adolescence, peaking around age 14, and declining thereafter. This pattern, however, is derived mainly from studies that specifically examined peer pressure to engage in antisocial behavior. In the present study, age differences and developmental change in resistance to peer influence were assessed using a new self-report instrument that separates susceptibility to peer pressure from willingness to engage in antisocial activity. Data from four ethnically and socioeconomically diverse samples comprising more than 3,600 males and females between the ages of 10 and 30 were pooled from one longitudinal and two cross-sectional studies. Results show that across all demographic groups, resistance to peer influences increases linearly between ages 14 and 18. In contrast, there is little evidence for growth in this capacity between ages 10 and 14 or between 18 and 30. Middle adolescence is an especially significant period for the development of the capacity to stand up for what one believes and resist the pressures of one’s peers to do otherwise. PMID:18020830

  14. Acetaminophen (paracetamol) oral absorption and clinical influences.

    PubMed

    Raffa, Robert B; Pergolizzi, Joseph V; Taylor, Robert; Decker, John F; Patrick, Jeffrey T

    2014-09-01

    Acetaminophen (paracetamol) is a widely used nonopioid, non-NSAID analgesic that is effective against a variety of pain types, but the consequences of overdose can be severe. Because acetaminophen is so widely available as a single agent and is increasingly being formulated in fixed-ratio combination analgesic products for the potential additive or synergistic analgesic effect and/or reduced adverse effects, accidental cumulative overdose is an emergent concern. This has rekindled interest in the sites, processes, and pharmacokinetics of acetaminophen oral absorption and the clinical factors that can influence these. The absorption of oral acetaminophen occurs primarily along the small intestine by passive diffusion. Therefore, the rate-limiting step is the rate of gastric emptying into the intestines. Several clinical factors can affect absorption per se or the rate of gastric emptying, such as diet, concomitant medication, surgery, pregnancy, and others. Although acetaminophen does not have the abuse potential of opioids or the gastrointestinal bleeding or organ adverse effects of NSAIDs, excess amounts can produce serious hepatic injury. Thus, an understanding of the sites and features of acetaminophen absorption--and how they might be influenced by factors encountered in clinical practice--is important for pain management using this agent. It can also provide insight for design of formulations that would be less susceptible to clinical variables. PMID:26013309

  15. Deformation twinning: Influence of strain rate

    SciTech Connect

    Gray, G.T. III

    1993-11-01

    Twins in most crystal structures, including advanced materials such as intermetallics, form more readily as the temperature of deformation is decreased or the rate of deformation is increased. Both parameters lead to the suppression of thermally-activated dislocation processes which can result in stresses high enough to nucleate and grow deformation twins. Under high-strain rate or shock-loading/impact conditions deformation twinning is observed to be promoted even in high stacking fault energy FCC metals and alloys, composites, and ordered intermetallics which normally do not readily deform via twinning. Under such conditions and in particular under the extreme loading rates typical of shock wave deformation the competition between slip and deformation twinning can be examined in detail. In this paper, examples of deformation twinning in the intermetallics TiAl, Ti-48Al-lV and Ni{sub 3}A as well in the cermet Al-B{sub 4}C as a function of strain rate will be presented. Discussion includes: (1) the microstructural and experimental variables influencing twin formation in these systems and twinning topics related to high-strain-rate loading, (2) the high velocity of twin formation, and (3) the influence of deformation twinning on the constitutive response of advanced materials.

  16. Influence of sea ice on Arctic precipitation

    PubMed Central

    Kopec, Ben G.; Feng, Xiahong; Michel, Fred A.; Posmentier, Eric S.

    2016-01-01

    Global climate is influenced by the Arctic hydrologic cycle, which is, in part, regulated by sea ice through its control on evaporation and precipitation. However, the quantitative link between precipitation and sea ice extent is poorly constrained. Here we present observational evidence for the response of precipitation to sea ice reduction and assess the sensitivity of the response. Changes in the proportion of moisture sourced from the Arctic with sea ice change in the Canadian Arctic and Greenland Sea regions over the past two decades are inferred from annually averaged deuterium excess (d-excess) measurements from six sites. Other influences on the Arctic hydrologic cycle, such as the strength of meridional transport, are assessed using the North Atlantic Oscillation index. We find that the independent, direct effect of sea ice on the increase of the percentage of Arctic sourced moisture (or Arctic moisture proportion, AMP) is 18.2 ± 4.6% and 10.8 ± 3.6%/100,000 km2 sea ice lost for each region, respectively, corresponding to increases of 10.9 ± 2.8% and 2.7 ± 1.1%/1 °C of warming in the vapor source regions. The moisture source changes likely result in increases of precipitation and changes in energy balance, creating significant uncertainty for climate predictions. PMID:26699509

  17. Motivational influences on response inhibition measures

    PubMed Central

    Leotti, Lauren A.; Wager, Tor D.

    2014-01-01

    Psychological research has placed great emphasis on inhibitory control due to its integral role in normal cognition and clinical disorders. The stop-signal task, in conjunction with the stop-signal reaction time (SSRT) measure, provides a well-established paradigm for measuring motor response inhibition. However, the influence of motivation and strategic decision-making on stop-signal performance and SSRT has not been examined. In the present study, we conceptualize the stop-signal paradigm as a decision-making task involving the tradeoff between fast responding and accurate inhibition. In four experiments, we demonstrate that this performance tradeoff is influenced by inherent motivational biases as well as explicit strategic control, resulting in systematic differences in conventional measures of inhibitory ability, such as SSRT. Within subjects, we found that SSRT was lower when participants favored correct stopping over fast responding, and was higher when participants favored fast responding over correct stopping. We present a novel variant of the stop-signal task that uses a monetary incentive structure to manipulate motivated speed-accuracy tradeoffs. By sampling performance at multiple tradeoff settings, we obtain a measure of inhibitory ability that is not confounded with motivational or strategic bias, and thus, more easily interpretable when comparing across participants. We present a working theoretical model to explain the effects of motivational context on response inhibition. PMID:20364928

  18. Policy influences on community trail development.

    PubMed

    Eyler, Amy A; Brownson, Ross C; Evenson, Kelly R; Levinger, David; Maddock, Jay E; Pluto, Delores; Troped, Philip J; Schmid, Thomas L; Carnoske, Cheryl; Richards, Katherine L; Steinman, Lesley E

    2008-06-01

    This study explores processes and policies that facilitate the development of community trails. With funding from Active Living Research and the research framework of the Physical Activity Policy Research Network (PAPRN), we conducted a multiple-site case study. A total of six trails in Hawaii, Massachusetts, Missouri, North Carolina, South Carolina, and Washington were chosen for study. The goals of this case study were to identify the policy influences on trail development, explore the roles of key players in trail development, and compare and contrast findings from the different trails. Trail development can be a long process. Some of the trails took over a decade to complete because of funding, opposition, and roadblocks in the form of design standard policies. Work in trail development requires a team of many players, and it is necessary to balance their varied motives to accomplish a shared overall goal. Foresight through the master planning process is also a vital component of successful trail development. Finally, community involvement is key. Communities contemplating trail development should explore the effects of policy on the trail projects reported here to proactively identify potential influence. PMID:18469168

  19. HOW MATE AVAILABILITY INFLUENCES FILIAL CANNIBALISM.

    PubMed

    Deal, Nicholas D S; Wong, Bob B M

    2016-03-01

    Parents sometimes eat their young to reduce the consequences of brood overcrowding, for nutritional gain, and/or to redirect investment toward future reproduction. It has been predicted that filial cannibalism should be more prevalent when mate availability is high as parents can more easily replace consumed young. Reviewing the available evidence--which comes almost exclusively from studies of paternal caring fish--we find support in some species, but not others. To explain this, we hypothesize that sexual selection against filial cannibalism and/or the tendency to acquire larger broods under conditions of high mate availability discourages filial cannibalism. Additionally, filial cannibalism might occur when mate availability is low to facilitate survival until access to mates improves. Since attractiveness can also influence remating opportunities, we review its effect on filial cannibalism, finding that attractive parents engage in less filial cannibalism. More research is needed to determine if this relationship is a result of individuals showing adaptive plasticity in filial cannibalism based on self-perceived attractiveness, or if the attractiveness of individuals is reduced by their propensity to commit filial cannibalism. More generally, to advance our understanding of how mate availability influences filial cannibalism, future studies should also focus on a wider range of taxa. PMID:27192779

  20. Speaker sex influences processing of grammatical gender.

    PubMed

    Vitevitch, Michael S; Sereno, Joan; Jongman, Allard; Goldstein, Rutherford

    2013-01-01

    Spoken words carry linguistic and indexical information to listeners. Abstractionist models of spoken word recognition suggest that indexical information is stripped away in a process called normalization to allow processing of the linguistic message to proceed. In contrast, exemplar models of the lexicon suggest that indexical information is retained in memory, and influences the process of spoken word recognition. In the present study native Spanish listeners heard Spanish words that varied in grammatical gender (masculine, ending in -o, or feminine, ending in -a) produced by either a male or a female speaker. When asked to indicate the grammatical gender of the words, listeners were faster and more accurate when the sex of the speaker "matched" the grammatical gender than when the sex of the speaker and the grammatical gender "mismatched." No such interference was observed when listeners heard the same stimuli, but identified whether the speaker was male or female. This finding suggests that indexical information, in this case the sex of the speaker, influences not just processes associated with word recognition, but also higher-level processes associated with grammatical processing. This result also raises questions regarding the widespread assumption about the cognitive independence and automatic nature of grammatical processes. PMID:24236155

  1. Speaker Sex Influences Processing of Grammatical Gender

    PubMed Central

    Vitevitch, Michael S.; Sereno, Joan; Jongman, Allard; Goldstein, Rutherford

    2013-01-01

    Spoken words carry linguistic and indexical information to listeners. Abstractionist models of spoken word recognition suggest that indexical information is stripped away in a process called normalization to allow processing of the linguistic message to proceed. In contrast, exemplar models of the lexicon suggest that indexical information is retained in memory, and influences the process of spoken word recognition. In the present study native Spanish listeners heard Spanish words that varied in grammatical gender (masculine, ending in -o, or feminine, ending in -a) produced by either a male or a female speaker. When asked to indicate the grammatical gender of the words, listeners were faster and more accurate when the sex of the speaker “matched” the grammatical gender than when the sex of the speaker and the grammatical gender “mismatched.” No such interference was observed when listeners heard the same stimuli, but identified whether the speaker was male or female. This finding suggests that indexical information, in this case the sex of the speaker, influences not just processes associated with word recognition, but also higher-level processes associated with grammatical processing. This result also raises questions regarding the widespread assumption about the cognitive independence and automatic nature of grammatical processes. PMID:24236155

  2. Do lipids influence the allergic sensitization process?

    PubMed Central

    Bublin, Merima; Eiwegger, Thomas; Breiteneder, Heimo

    2014-01-01

    Allergic sensitization is a multifactorial process that is not only influenced by the allergen and its biological function per se but also by other small molecular compounds, such as lipids, that are directly bound as ligands by the allergen or are present in the allergen source. Several members of major allergen families bind lipid ligands through hydrophobic cavities or electrostatic or hydrophobic interactions. These allergens include certain seed storage proteins, Bet v 1–like and nonspecific lipid transfer proteins from pollens and fruits, certain inhalant allergens from house dust mites and cockroaches, and lipocalins. Lipids from the pollen coat and furry animals and the so-called pollen-associated lipid mediators are codelivered with the allergens and can modulate the immune responses of predisposed subjects by interacting with the innate immune system and invariant natural killer T cells. In addition, lipids originating from bacterial members of the pollen microbiome contribute to the outcome of the sensitization process. Dietary lipids act as adjuvants and might skew the immune response toward a TH2-dominated phenotype. In addition, the association with lipids protects food allergens from gastrointestinal degradation and facilitates their uptake by intestinal cells. These findings will have a major influence on how allergic sensitization will be viewed and studied in the future. PMID:24880633

  3. Game Theory, Conditional Preferences, and Social Influence

    PubMed Central

    Stirling, Wynn C.; Felin, Teppo

    2013-01-01

    Neoclassical noncooperative game theory is based on a simple, yet powerful synthesis of mathematical and logical concepts: unconditional and immutable preference orderings and individual rationality. Although this structure has proven useful for characterizing competitive multi-player behavior, its applicability to scenarios involving complex social relationships is problematic. In this paper we directly address this limitation by the introduction of a conditional preference structure that permits players to modulate their preference orderings as functions of the preferences of other players. Embedding this expanded preference structure in a formal and graphical framework provides a systematic approach for characterizing a complex society. The result is an influence network that allows conditional preferences to propagate through the community, resulting in an emergent social model which characterizes all of the social relationships that exist and which leads to solution concepts that account for both group and individual interests. The Ultimatum game is presented as an example of how social influence can be modeled with conditional preferences. PMID:23451078

  4. Estimating the noise influence on recovering reflectances

    NASA Astrophysics Data System (ADS)

    Hironaga, Mikiya; Shimano, Noriyuki

    2010-01-01

    The evaluation of the noise present in the image acquisition system and the influence of the noise is essential to image acquisition. However the mean square errors (MSE) is not divided into two terms, i.e., the noise independent MSE (MSEfree) and noise dependent MSE (MSEnoise) were not discussed separately before. The MSEfree depends on the spectral characteristics of a set of sensors, illuminations and reflectances of imaged objects and the MSEfree arises in the noise free case, however MSEnoise originates from the noise present image acquisition system. One of the authors (N.S.) already proposed a model to separate the MSE into the two factors and also proposed a model to estimate noise variance present in image acquisition systems. By the use of this model, we succeeded in the expression of the MSEnoise as a function of the noise variance and showed that the experimental results agreed fairly well with the expression when the Wiener estimation was used for the recovery. The present paper shows the extended expression for the influence of the system noise on the MSEnoise and the experimental results to show the trustworthiness of the expression for the regression model, Imai-Berns model and finite dimensional linear model.

  5. Authigenic minerals: Biologically influenced and induced organomineralization

    NASA Astrophysics Data System (ADS)

    Dupraz, Christophe

    2016-04-01

    Organominerals are minerals precipitated by interactions with organic matter without enzymatic control. Organomineralization of authigenic carbonate minerals depends on two key components: (1) the "carbonate alkalinity engine" impacting the calcium carbonate saturation index and (2) the organic matrix comprised of extracellular organic matter (EOM), which provides a template for carbonate nucleation. The alkalinity engine can be "intrinsic" when microbial metabolisms increase supersaturation or lower the kinetic barrier of precipitation, or "extrinsic" when the physicochemical environment creates the conditions for mineral formation. The organic matrix produced by various communities within the microbial mats is known to influence nucleation, morphology and mineralogy of minerals through binding of cations. By playing with these two key components, three types of authigenic minerals can be formed: (1) a purely physicochemical precipitation on an abiotic substrate, (2) a precipitation "influenced" by the presence of an organic matrix but resulting from a physicochemical forcing (environmentally driven), or (3) a "microbially-induced" precipitation, in which both supersaturation and organic matrix are resulting from microbial activity. In this keynote, we will review important processes involved in the precipitation of authigenic carbonate minerals in modern microbial mats and open the discussion on the potential use of authigenic carbonate minerals as biosignatures in the fossil record.

  6. Urban tree influences on ultraviolet irradiance

    NASA Astrophysics Data System (ADS)

    Heisler, Gordon M.; Grant, Richard H.; Gao, Wei

    2002-01-01

    Many of the effects of ultraviolet radiation (UVR) on people and their environment--damage to various materials, survival of insects and microbial pathogens, growth of vegetation, and adverse or beneficial effects on human health--are modified by the presence of trees. Human epidemiological investigations generally consider exposure as given by indices of UVR irradiance on horizontal surfaces in the open. Though many people are exposed to UVR while reclining at a beach or swimming pool, thus experiencing irradiance on essentially horizontal surfaces in the open, exposure to UVR during daily routines in urban areas may also be important in affecting human health. Tree influences on UVR irradiance, particularly in the UVB, can differ substantially from influences on the visible portion of the solar spectrum. Trees greatly reduce UVB irradiance in their shade when they obscure both the sun and sky. Where trees obscure the sun but leave much of the sky in view, UVB irradiance will be greater than suggested by the visible shadow. In small sunny areas near trees that block much of the sky from view, UVB irradiance is reduced substantially, whereas visible irradiance may be nearly as great or slightly greater than in the open.

  7. Do social utility judgments influence attentional processing?

    PubMed

    Shore, Danielle M; Heerey, Erin A

    2013-10-01

    Research shows that social judgments influence decision-making in social environments. For example, judgments about an interaction partners' trustworthiness affect a variety of social behaviors and decisions. One mechanism by which social judgments may influence social decisions is by biasing the automatic allocation of attention toward certain social partners, thereby shaping the information people acquire. Using an attentional blink paradigm, we investigate how trustworthiness judgments alter the allocation of attention to social stimuli in a set of two experiments. The first experiment investigates trustworthiness judgments based solely on a social partner's facial appearance. The second experiment examines the effect of trustworthiness judgments based on experienced behavior. In the first, strong appearance-based judgments (positive and negative) enhanced stimulus recognizability but did not alter the size of the attentional blink, suggesting that appearance-based social judgments enhance face memory but do not affect pre-attentive processing. However, in the second experiment, in which judgments were based on behavioral experience rather than appearance, positive judgments enhanced pre-attentive processing of trustworthy faces. This suggests that a stimulus's potential benefits, rather than its disadvantages, shape the automatic distribution of attentional resources. These results have implications for understanding how appearance- and behavior-based social cues shape attention distribution in social environments. PMID:23887150

  8. Sleep quality influences subsequent motor skill acquisition.

    PubMed

    Appleman, Erica R; Albouy, Genevieve; Doyon, Julien; Cronin-Golomb, Alice; King, Bradley R

    2016-06-01

    While the influence of sleep on motor memory consolidation has been extensively investigated, its relation to initial skill acquisition is less well understood. The purpose of the present study was to investigate the influence of sleep quality and quantity on subsequent motor skill acquisition in young adults without sleep disorders. Fifty-five healthy adults (mean age = 23.8 years; 34 women) wore actigraph wristbands for 4 nights, which provided data on sleep patterns before the experiment, and then returned to the laboratory to engage in a motor sequence learning task (explicit 5-item finger sequence tapping task). Indicators of sleep quality and quantity were then regressed on a measure of motor skill acquisition (Gains Within Training, GWT). Wake After Sleep Onset (WASO; i.e., the total amount of time the participants spent awake after falling asleep) was significantly and negatively related to GWT. This effect was not because of general arousal level, which was measured immediately before the motor task. Conversely, there was no relationship between GWT and sleep duration or self-reported sleep quality. These results indicate that sleep quality, as assessed by WASO and objectively measured with actigraphy before the motor task, significantly impacts motor skill acquisition in young healthy adults without sleep disorders. (PsycINFO Database Record PMID:26881313

  9. Occupational influences on retirement, disability, and death.

    PubMed

    Hayward, M D; Grady, W R; Hardy, M A; Sommers, D

    1989-08-01

    This research examines the alternative mechanisms by which occupations influence the nature and timing of older men's labor force withdrawal. We specifically assess the extent to which occupational factors operate directly and indirectly on exiting events and whether occupations constrain traditional determinants of labor force participation. Based on a discrete-time hazard modeling approach, the results substantiate that the occupational task activities--substantive complexity and physical demands--are key elements of the work environment that are evaluated against nonwork alternatives. In the case of retirement, these aspects of occupational attractiveness function as a dominant and direct force in retirement decision making. With regard to disability, the occupational attribute of substantive complexity operates as an indirect advantage (through higher wages) by reducing the risk of disability. Indicators of career continuity also influence retirement among older workers. Finally, the results suggest that financial characteristics and health problems are central to the distribution of older workers across the alternative destination statuses of retirement, disability, and death. PMID:2529146

  10. Remindings influence the interpretation of ambiguous stimuli.

    PubMed

    Tullis, Jonathan G; Braverman, Michael; Ross, Brian H; Benjamin, Aaron S

    2014-02-01

    Remindings-stimulus-guided retrievals of prior events-may help us interpret ambiguous events by linking the current situation to relevant prior experiences. Evidence suggests that remindings play an important role in interpreting complex ambiguous stimuli (Ross & Bradshaw Memory & Cognition, 22, 591-605, 1994); here, we evaluate whether remindings will influence word interpretation and memory in a new paradigm. Learners studied words on distinct visual backgrounds and generated a sentence for each word. Homographs were preceded by a biasing cue on the same background three items earlier, preceded by a biasing cue on a different background three items earlier, or followed by a biasing cue on the same background three items later. When biasing cues preceded the homographs on the same backgrounds as the homographs, the meanings of the homographs in learner-generated sentences were consistent with the biasing cues more often than in the other two conditions. These results show that remindings can influence word interpretation. In addition, later memory for the homographs and cues was greater when the meaning of the homograph in the sentence was consistent with the earlier biasing cue, suggesting that remindings enhanced mnemonic performance. Remindings play an important role in how we interpret ambiguous stimuli and enhance memory for the involved material. PMID:23835617

  11. Influence of organizational factors on safety

    SciTech Connect

    Haber, S.B.; Metlay, D.S.; Crouch, D.A.

    1990-01-01

    There is a need for a better understanding of exactly how organizational management factors at a nuclear power plant (NPP) affect plant safety performance, either directly or indirectly, and how these factors might be observed, measured, and evaluated. The purpose of this research project is to respond to that need by developing a general methodology for characterizing these organizational and management factors, systematically collecting information on their status and integrating that information into various types of evaluative activities. Research to date has included the development of the Nuclear Organization and Management Analysis Concept (NOMAC) of a NPP, the identification of key organizational and management factors, and the identification of the methods for systematically measuring and analyzing the influence of these factors on performance. Most recently, two field studies, one at a fossil fuel plant and the other at a NPP, were conducted using the developed methodology. Results are presented from both studies highlighting the acceptability, practicality, and usefulness of the methods used to assess the influence of various organizational and management factors including culture, communication, decision-making, standardization, and oversight. 6 refs., 3 figs., 1 tab.

  12. The influence of industry on dental education.

    PubMed

    Gillis, Martin R; McNally, Mary E

    2010-10-01

    Academic dental institutions face the growing challenge of securing the resources needed to develop a curriculum that incorporates current innovation and technology to ensure that students' learning experiences are relevant to current dental practice. As a result, university-industry relationships are becoming increasingly common in academe. While these relationships facilitate curriculum relevance, they also expose students to external market forces. The purpose of this study was to explore the influence of industry on dental education using a qualitative research study design. Analysis of semistructured interviews with thirteen Dalhousie University dental faculty members revealed two primary themes that suggest a tension between the traditional hierarchical organizational structures guiding curriculum (i.e., authoritarianism) and industry's quest for profit (i.e., entrepreneurialism). Additional themes demonstrate a belief that industry directly influences students' knowledge and understanding of evidence as well as their experience with both the formal and informal curricula. Industry's presence in academe is a concern. Dental educators, as stewards of the profession, must be nimble in brokering industry's presence without compromising the integrity of both the educational program and the teaching institution as a whole. PMID:20930240

  13. Influence of aberrations in microholographic recording

    NASA Astrophysics Data System (ADS)

    Katayama, Ryuichi

    2015-11-01

    The influence of various types of aberrations (spherical, coma, and astigmatic) of recording and readout beams on the readout signal in a microholographic recording was investigated through a numerical simulation. The simulation conditions were that the wavelength of the laser was 405 nm and the numerical aperture of the objective lenses was 0.85. The tolerance of the root-mean-square (RMS) wavefront aberrations was defined as the aberration when the normalized signal level decreased to 0.8. Among the three types of aberrations, the influence of the spherical aberration was the most significant. When both the recording and readout beams were aberrated and the signs of the aberrations were in the worst case, the tolerance of the RMS wavefront aberrations was less than half of the Maréchal's criterion. Moreover, when the RMS wavefront aberrations of the recording and readout beams were within the above tolerance, the bit intervals of 0.13 and 0.65 μm in the inplane and vertical directions, respectively, which correspond to the recording density of 91 bit/μm3 (recording capacity of 16 TB for a 120-mm-diameter optical disk having a 300-μm-thick recording layer), were shown to be feasible for confocal detection with an allowable signal-to-noise ratio.

  14. Genetic correlates influencing immunopathogenesis of HIV infection

    PubMed Central

    Sharma, Gaurav; Kaur, Gurvinder; Mehra, Narinder

    2011-01-01

    Variability to HIV infection, its progression as well as responsiveness to antiretroviral therapy (ART) is observed among individuals including viraemia controllers or exposed uninfected, rapid versus slow progressors and ART responders compared to non responders. This differential responsiveness/vulnerability to HIV-1 is governed by multiple host genetic factors that include HLA, cytokines, chemokines, their receptors and others. This review highlights the influence of these genetic factors on HIV/AIDS outcome; however, in India, the information in this area is very limited and most of these genetic studies have been conducted in Caucasian and South African populations. Considering, the population specific differences in the frequencies of protective or susceptibility favouring alleles and their influence on the disease outcome, it is of utmost importance to strengthen ongoing efforts towards defining largely unknown genetic propensity in Indian population, particularly by recruitment of large cohorts of well categorized exposed uninfected individuals, rapid, long term non progressors and elite viraemic controllers. Multi-parametric analysis of these potentially interactive immunogenetic variables in these cohorts may help to define potential targets for diagnostics and therapy in a population specific manner. PMID:22310811

  15. Quit interest influences smoking cue-reactivity.

    PubMed

    Veilleux, Jennifer C; Skinner, Kayla D; Pollert, Garrett A

    2016-12-01

    Interest in quitting smoking is important to model in cue-reactivity studies, because the craving elicited by cue exposure likely requires different self-regulation efforts for smokers who are interested in quitting compared to those without any quit interest. The objective of the current study was to evaluate the role of quit interest in how cigarette cue exposure influences self-control efforts. Smokers interested in quitting (n=37) and smokers with no interest in quitting (n=53) were randomly assigned to a cigarette or neutral cue exposure task. Following the cue exposure, all participants completed two self-control tasks, a measure of risky gambling (the Iowa Gambling Task) and a cold pressor tolerance task. Results indicated that smokers interested in quitting had worse performance on the gambling task when exposed to a cigarette cue compared to neutral cue exposure. We also found that people interested in quitting tolerated the cold pressor task for a shorter amount of time than people not interested in quitting. Finally, we found that for people interested in quitting, exposure to a cigarette cue was associated with increased motivation to take steps toward decreasing use. Overall these results suggest that including quit interest in studies of cue reactivity is valuable, as quit interest influenced smoking cue-reactivity responses. PMID:27487082

  16. Social appraisal influences recognition of emotions.

    PubMed

    Mumenthaler, Christian; Sander, David

    2012-06-01

    The notion of social appraisal emphasizes the importance of a social dimension in appraisal theories of emotion by proposing that the way an individual appraises an event is influenced by the way other individuals appraise and feel about the same event. This study directly tested this proposal by asking participants to recognize dynamic facial expressions of emotion (fear, happiness, or anger in Experiment 1; fear, happiness, anger, or neutral in Experiment 2) in a target face presented at the center of a screen while a contextual face, which appeared simultaneously in the periphery of the screen, expressed an emotion (fear, happiness, anger) or not (neutral) and either looked at the target face or not. We manipulated gaze direction to be able to distinguish between a mere contextual effect (gaze away from both the target face and the participant) and a specific social appraisal effect (gaze toward the target face). Results of both experiments provided evidence for a social appraisal effect in emotion recognition, which differed from the mere effect of contextual information: Whereas facial expressions were identical in both conditions, the direction of the gaze of the contextual face influenced emotion recognition. Social appraisal facilitated the recognition of anger, happiness, and fear when the contextual face expressed the same emotion. This facilitation was stronger than the mere contextual effect. Social appraisal also allowed better recognition of fear when the contextual face expressed anger and better recognition of anger when the contextual face expressed fear. PMID:22288528

  17. Environmental and genetic influences on early attachment

    PubMed Central

    Gervai, Judit

    2009-01-01

    Attachment theory predicts and subsequent empirical research has amply demonstrated that individual variations in patterns of early attachment behaviour are primarily influenced by differences in sensitive responsiveness of caregivers. However, meta-analyses have shown that parenting behaviour accounts for about one third of the variance in attachment security or disorganisation. The exclusively environmental explanation has been challenged by results demonstrating some, albeit inconclusive, evidence of the effect of infant temperament. In this paper, after reviewing briefly the well-demonstrated familial and wider environmental influences, the evidence is reviewed for genetic and gene-environment interaction effects on developing early attachment relationships. Studies investigating the interaction of genes of monoamine neurotransmission with parenting environment in the course of early relationship development suggest that children's differential susceptibility to the rearing environment depends partly on genetic differences. In addition to the overview of environmental and genetic contributions to infant attachment, and especially to disorganised attachment relevant to mental health issues, the few existing studies of gene-attachment interaction effects on development of childhood behavioural problems are also reviewed. A short account of the most important methodological problems to be overcome in molecular genetic studies of psychological and psychiatric phenotypes is also given. Finally, animal research focusing on brain-structural aspects related to early care and the new, conceptually important direction of studying environmental programming of early development through epigenetic modification of gene functioning is examined in brief. PMID:19732441

  18. Influence of electric field on cellular migration

    NASA Astrophysics Data System (ADS)

    Guido, Isabella; Bodenschatz, Eberhard

    Cells have the ability to detect continuous current electric fields (EFs) and respond to them with a directed migratory movement. Dictyostelium discoideum (D.d.) cells, a key model organism for the study of eukaryotic chemotaxis, orient and migrate toward the cathode under the influence of an EF. The underlying sensing mechanism and whether it is shared by the chemotactic response pathway remains unknown. Whereas genes and proteins that mediate the electric sensing as well as that define the migration direction have been previously investigated in D.d. cells, a deeper knowledge about the cellular kinematic effects caused by the EF is still lacking. Here we show that besides triggering a directional bias the electric field influences the cellular kinematics by accelerating the movement of cells along their path. We found that the migratory velocity of the cells in an EF increases linearly with the exposure time. Through the analysis of the PI3K and Phg2 distribution in the cytosol and of the cellular adherence to the substrate we aim at elucidating whereas this speed up effect in the electric field is due to either a molecular signalling or the interaction with the substrate. This work is part of the MaxSynBio Consortium which is jointly funded by the Federal Ministry of Education and Research of Germany and the Max Planck Society.

  19. Influence of fiber packing structure on permeability

    NASA Technical Reports Server (NTRS)

    Cai, Zhong; Berdichevsky, Alexander L.

    1993-01-01

    The study on the permeability of an aligned fiber bundle is the key building block in modeling the permeability of advanced woven and braided preforms. Available results on the permeability of fiber bundles in the literature show that a substantial difference exists between numerical and analytical calculations on idealized fiber packing structures, such as square and hexagonal packing, and experimental measurements on practical fiber bundles. The present study focuses on the variation of the permeability of a fiber bundle under practical process conditions. Fiber bundles are considered as containing openings and fiber clusters within the bundle. Numerical simulations on the influence of various openings on the permeability were conducted. Idealized packing structures are used, but with introduced openings distributed in different patterns. Both longitudinal and transverse flow are considered. The results show that openings within the fiber bundle have substantial effect on the permeability. In the longitudinal flow case, the openings become the dominant flow path. In the transverse flow case, the fiber clusters reduce the gap sizes among fibers. Therefore the permeability is greatly influenced by these openings and clusters, respectively. In addition to the porosity or fiber volume fraction, which is commonly used in the permeability expression, another fiber bundle status parameter, the ultimate fiber volume fraction, is introduced to capture the disturbance within a fiber bundle.

  20. Influence of sea ice on Arctic precipitation.

    PubMed

    Kopec, Ben G; Feng, Xiahong; Michel, Fred A; Posmentier, Eric S

    2016-01-01

    Global climate is influenced by the Arctic hydrologic cycle, which is, in part, regulated by sea ice through its control on evaporation and precipitation. However, the quantitative link between precipitation and sea ice extent is poorly constrained. Here we present observational evidence for the response of precipitation to sea ice reduction and assess the sensitivity of the response. Changes in the proportion of moisture sourced from the Arctic with sea ice change in the Canadian Arctic and Greenland Sea regions over the past two decades are inferred from annually averaged deuterium excess (d-excess) measurements from six sites. Other influences on the Arctic hydrologic cycle, such as the strength of meridional transport, are assessed using the North Atlantic Oscillation index. We find that the independent, direct effect of sea ice on the increase of the percentage of Arctic sourced moisture (or Arctic moisture proportion, AMP) is 18.2 ± 4.6% and 10.8 ± 3.6%/100,000 km(2) sea ice lost for each region, respectively, corresponding to increases of 10.9 ± 2.8% and 2.7 ± 1.1%/1 °C of warming in the vapor source regions. The moisture source changes likely result in increases of precipitation and changes in energy balance, creating significant uncertainty for climate predictions. PMID:26699509