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Sample records for acidic oligotrophic fen

  1. Reconstruction of annual carbon dynamics and balance for an oligotrophic pine fen

    Energy Technology Data Exchange (ETDEWEB)

    Alm, J.; Silvola, J.; Aaltonen, H. [Joensuu Univ. (Finland). Dept. of Biology; Talanov, A.; Ikkonen, E. [Karelian Research Centre of Russian Academy of Sciences (Russian Federation). Inst. of Biology; Nykaenen, H.; Martikainen, P.J. [National Public Health Inst. Kuopio (Finland). Dept. of Environmental Microbiology

    1996-12-31

    Atmospheric carbon dioxide (CO{sub 2}) is bound by mire vegetation in photosynthesis during the growing season, and is re-released by respiration of plants, soil animals and microorganisms consuming dead organic matter. A small proportion of annual primary production may fall below the water table to anoxic conditions and thus escapes the oxidative decomposition. Also from anoxic peat, carbon is released with clear seasonal and spatial variation as methane (CH{sub 4}.). The rate of carbon accumulation in peat depends on the annual inbalance of plant production and litter decomposition. Exchange of CO{sub 2} and CH{sub 4} between peat, vegetation and the atmosphere thus reflects the dynamics of carbon flows in the ecosystem. Net ecosystem CO{sub 2} exchange (PN), total CO{sub 2} release (RTOT) and CH{sub 4} release (D) from different treeless surfaces of low-sedge Sphagnum papillosum pine fen was studied in eastern Finland. (8 refs.)

  2. Remotely sensed hydrological isolation : A key factor predicting plant species distribution in fens

    OpenAIRE

    Sanders, M.E.

    1999-01-01

    In fens the species composition, vegetation structure and succession rate are determined by vegetation management and water chemistry, particularly by the base status and nutrient status. Base-rich and nutrient-rich surface water causes fens to become eutrophied, which leads to an increased biomass production. When part of fens becomes isolated from this surface water (hydrological isolation), it acidifies due to acidic and oligotrophic rainwater dominance. One consequence of decreasing water...

  3. Drying-Rewetting and Flooding Impact Denitrifier Activity Rather than Community Structure in a Moderately Acidic Fen

    Science.gov (United States)

    Palmer, Katharina; Köpp, Julia; Gebauer, Gerhard; Horn, Marcus A.

    2016-01-01

    Wetlands represent sources or sinks of the greenhouse gas nitrous oxide (N2O). The acidic fen Schlöppnerbrunnen emits denitrification derived N2O and is also capable of N2O consumption. Global warming is predicted to cause more extreme weather events in future years, including prolonged drought periods as well as heavy rainfall events, which may result in flooding. Thus, the effects of prolonged drought and flooding events on the abundance, community composition, and activity of fen denitrifiers were investigated in manipulation experiments. The water table in the fen was experimentally lowered for 8 weeks in 2008 and raised for 5.5 months in 2009 on three treatment plots, while three plots were left untreated and served as controls. In situ N2O fluxes were rather unaffected by the drought treatment and were marginally increased by the flooding treatment. Samples were taken before and after treatment in both years. The structural gene markers narG and nosZ were used to assess possible changes in the nitrate reducer and denitrifier community in response to water table manipulations. Detected copy numbers of narG and nosZ were essentially unaffected by the experimental drought and flooding. Terminal restriction fragment length polymorphism (TRFLP) patterns of narG and nosZ were similar before and after experimental drought or experimental flooding, indicating a stable nitrate reducer and denitrifier community in the fen. However, certain TRFs of narG and nosZ transcripts responded to experimental drought or flooding. Nitrate-dependent Michaelis-Menten kinetics were assessed in anoxic microcosms with peat samples taken before and 6 months after the onset of experimental flooding. Maximal reaction velocities vmax were higher after than before flooding in samples from treament but not in those from control plots taken at the same time. The ratio of N2O to N2O + N2 was lower in soil from treatment plots after flooding than in soil from control plots, suggesting

  4. 结构特异性核酸酶FEN1对HBV复制的影响%Effect of structure-specific nucleic acid enzyme FEN1 on HBV replication

    Institute of Scientific and Technical Information of China (English)

    潘万龙; 方岩; 许舸; 单雪峰; 徐蕾; 陈可; 黄爱龙; 胡接力

    2012-01-01

    Objective To lay the foundation for working out new clinical treatment strategies by studying the effect of host factor FEN1 on HBV replication. Methods FEN1 overexpression lentiviral plasmid was constructed with its sequence identified by restriction enzyme digestion and transfected into 293 FT cells. FEN1 protein expression was detected by Western blotting. The plasmid was transfected into stable cell lines with HBV replication. The plasmid pLenti6/V5-D-TOPO was modified by lentivirus packaging and non-transfected plasmid cells served as controls. HBsAg in medium supernatant was detected by ELISA. HBV DNA was detected by RT-PCR and Southern blotting, respectively. Results The plasmid extracted from positive clones was digested by restriction endonuclease, and a bright band was observed in FEN1 and linear plasmid, respectively. The lentiviral plasmid sequencing showed that the sequence was inserted correctly. Western blot analysis displayed that the FEN1 protein expression level was 2-3 fold higher in transfected plasmid cells than in non-transfected plasmid cells. FENl-overexpressed plasmid could transfect stable cell lines with HBV replication. ELISA demonstrated positive HBsAg in medium supernatant with a D450 value of 1.982 ±0.032. RT-PCR revealed intracellular viral DNA with an absolutely-quantified copy number of 1. 18 × 109 . Southern blot analysis indicated that the HBV replication level was significantly up-regulated. Conclusion Structure-specific nuclease FEN1 can significantly promote HBV DNA replication and is thus one of the important regulatory factors for virus replication.%目的 探索宿主因子FEN1对HBV复制过程的影响.方法 构建FEN1过表达慢病毒质粒,酶切鉴定并测序,转染293FT细胞,Western blot检测FEN1蛋白表达.将该质粒转染HBV复制稳定细胞系,设立慢病毒包装改造质粒pLenti6/V5-D-TOPO和不转染质粒的细胞作为对照.ELISA检测细胞上清,Southern blot及Real-time PCR检测HBV DNA

  5. Key plant species and succession patterns associated to past fen-bog transitions - perspective to future

    Science.gov (United States)

    Väliranta, Minna; Luoto, Miska; Juutinen, Sari; Korhola, Atte; Tuittila, Eeva-stiina

    2016-04-01

    Minerotrophic fens and ombrotrophic bogs differ in their hydrology, vegetation and carbon dynamics and their geographical distribution seems to be linked to certain climate parameters, such as temperature and effective precipitation. Currently bogs dominate the southern boreal zone but the climate warming with altered temperature and effective precipitation may shift the distribution of bog zone northwards. In this study, we first used plant macrofossil method and radiocarbon analysis to identify and date past fen-bog transitions. These transitions were compared to major Holocene climate phases. Subsequently, palaeoecological data were associated to ecological and environmental data collected along the current fen-bog ecotone in Finland. We identified three successional phases 1) initial minerotrophic fen phase 2) Eriophorum vaginatum-dominated oligotrophic fen phase which was followed by 3) ombrorophic bog phase. Duration of these phases varied but late Holocene timing of fen-bog transition showed some consistency. Based on palaeoecological data 57 % of the modern ecotone peatlands were classified to be in a fen phase, 10 % were in an Eriophorum-dominated phase and 33 % were going through a transition from fen to bog. The study showed that regime shifts are driven by autogenic succession and climate but also fires may efficiently control succession pathways. Our results support the hypothesis that climate change can promote the ombrotrophication process in the southern border of the fen-bog ecotone due to changes in hydrology balance.

  6. Método para a Determinação de Ácidos Fenólicos na Parede Celular de Forragens Method for Phenolic Acid Determination in Forage Cell Wall

    Directory of Open Access Journals (Sweden)

    Francisco Carlos Deschamps

    2002-07-01

    Full Text Available Há fatores que limitam a digestão das forragens tropicais e estão associados à dinâmica dos ácidos fenólicos da parede celular. Os estudos destes compostos em forragens podem ser facilitados pela disponibilidade de métodos sensíveis que permitam o processamento de grande número de amostras. No presente trabalho, descreve-se um método para a determinação de ácidos fenólicos na parede celular de forragens, utilizando cromatografia líquida de alta eficiência (CLAE. Bagaço de cana, capim-elefante e folhas de mandioca foram utilizados como amostras experimentais. Para remover substâncias solúveis de baixa massa molecular, foram testados etanol 80% e o detergente neutro, determinando seus efeitos sobre a recuperação das moléculas e benefícios no perfil cromatográfico. Para a obtenção dos ácidos fenólicos livres, as amostras foram solubilizadas em NaOH 1 mol/L, 20ºC por 24 horas. O método proposto foi adequado para a determinação de ácidos fenólicos, apresentando grande sensibilidade e produtividade no laboratório. Para minimizar os efeitos negativos da formação de sal resultante da neutralização ácida do extrato alcalino, sugere-se a diluição da amostra ou a injeção de pequeno volume (5 uL no aparelho. O efeito da utilização de solventes como etanol 80% ou detergente neutro é distinto sobre as amostras das gramíneas e leguminosas. A quantidade de extrativos nas folhas de mandioca foi superior a do bagaço de cana e capim-elefante. A concentração de ácidos fenólicos foi pouco alterada pela ação dos solventes, sendo maior nas amostras de bagaço de cana e capim-elefante, em relação às folhas de mandioca. O método apresentado constitui-se em uma importante ferramenta para o estudo dos ácidos fenólicos na parede celular de forragens tropicais.Factors that limit the digestion of tropical forages are associated to the dynamic of cell wall phenolic acids. The study of these compounds in forages may

  7. Diatomáceas epilíticas de águas oligotróficas e ácidas do Sudeste do Brasil Epilithic diatoms from acidic and oligotrophic waters in Southeast Brazil

    Directory of Open Access Journals (Sweden)

    Luís Gustavo de Castro Canani

    2011-03-01

    Full Text Available Poucos estudos tem abordado a flora de diatomáceas de sistemas oligotróficos do Brasil. São apresentados os resultados da composição taxonômica e distribuição espacial e temporal de diatomáceas no rio do Salto, situado no Parque Estadual do Ibitipoca, Minas Gerais (21º40'-21º44'S e 43º52'-43º55'W. As águas desse rio possuem pH entre 4,2 e 5,5 e concentração de ortofosfato entre 1,37 e 10,98 µg.L-1. O estudo baseia-se na análise de 80 amostras coletadas em oito estações no leito rochoso do rio, em janeiro e julho de 2004, períodos de chuva e estiagem, respectivamente. Um total de 15 espécies e duas variedades taxonômicas, distribuídas em oito gêneros e oito famílias foram descritas e ilustradas, com destaque para o gênero Eunotia Ehrenberg. O estudo sobre diatomáceas bentônicas em ambientes lóticos é pioneiro no estado de Minas Gerais, sendo registradas 14 novas citações, das quais Fragilariforma stevensonii Metzeltin & Lange-Bertalot, Eunotia pirarucu Metzeltin & Lange Betalot, Nupela giluwensis Vyverman & Compère e Sellaphora blackfordensis Mann & Droop são primeiros registros para o Brasil.Few studies have been done on the diatom flora of acidic and oligotrophic environments from Brazil. We present the taxonomic composition and distribution of diatoms of Salto River, situated at Ibitipoca State Park, Minas Gerais (21º40'-21º44'S; 43º52'-43º55'W. The pH values ranged from 4.2 to 5.5 and orthophosphate was between 1.37 and 10.98 µg.L-1. The study is based on the analysis of 80 samples collected at eight stations in the rocky stream bed, in January and July 2004, rainy and dry seasons, respectively. A total of 15 species and two taxonomic varieties distributed in eight genera and eight families were described and illustrated, notably the Eunotia Ehrenberg genus. The study of benthic diatoms in lotic systems is pioneer in Minas Gerais state; 14 new records were recorded of which Fragilariforma stevensonii

  8. Calcareous Fens - Source Feature Points

    Data.gov (United States)

    Minnesota Department of Natural Resources — Pursuant to the provisions of Minnesota Statutes, section 103G.223, this database contains points that represent calcareous fens as defined in Minnesota Rules, part...

  9. Lowland Bogs, Fens and Reedswamps

    OpenAIRE

    Bracken, Fintan; Smiddy, Patrick

    2012-01-01

    This chapter reviews the current and historical studies of the bird communities of lowland bogs, fens and reedswamps in Ireland. The habitat types and bird communities described include raised bogs, cutover and cutaway peatlands and reedswamps.

  10. N and P addition inhibits growth of rich fen bryophytes

    DEFF Research Database (Denmark)

    Andersen, Dagmar Kappel; Ejrnæs, Rasmus; Riis, Tenna

    2016-01-01

    vernicosus and paludella squarrosa) rich fen bryophytes were grown in mixed culture and subjected to rainwater or groundwater and three levels of N (0, 1 and 3 mg N L-1) and P (0, 0.05 and 0.1 mg P NL-1). All species responded negatively to higher N-levels and three of four species responded negatively...... to rainwater and higher P-levels. C. cuspidata had highest relative growth rate in all treatments, and the infrequently occurringrare species had lower relative growth rate and were more negatively affected by high levels of N than the frequently occurringcommon species. A negative effect of rainwater seemed...... to be caused by higher background levels of N in rainwater compared to groundwater rather than a pH-effect per se. We found a negative effect of high initial bryophyte density in three of four species indicating density dependent inhibition between species.We suggest that maintenance of oligotrophic conditions...

  11. Actividad antioxidante de los compuestos fenólicos

    Directory of Open Access Journals (Sweden)

    Maestro Durán, R.

    1993-04-01

    Full Text Available This review deals with the oxidation processes induced by light and atmospheric oxygen, as well as the protective action on antioxidant compounds. The available data on the synthetic antioxidants and the problems associated to their use, together with the presence of natural phenolic antioxidants in plants, have been revised. These phenolic antioxidants have been classified in families: phenolic alcohols and acids, cinnamic acids, coumarins, favonoids (flavones and isoflavones, flavonols, flavanones and other phenolic compounds.

    Este trabajo recoge los estudios sobre los mecanismos de oxidación producida por la luz y el oxígeno del aire y sobre la protección de los compuestos antioxidantes contra esta oxidación. Se han revisado los datos existentes sobre los inconvenientes de los antioxidantes sintéticos, que aconsejan sustituirlos por otros naturales y sobre la presencia de antioxidantes naturales de carácter fenólico en las plantas. Los antioxidantes fenólicos se han agrupado por familias: alcoholes y ácidos fenólicos, ácidos cinámicos, cumarinas, flavonoides (flavonas e isoflavonas, flavonoles, flavanonas y otros compuestos fenólicos.

  12. Extração, análise e distribuição dos ácidos fenólicos em genótipos pigmentados e não pigmentados de arroz (Oryza sativa L. Extraction, analysis and distribution of phenolic acids in pigmented and non-pigmented genotypes of rice (Oryza sativa L.

    Directory of Open Access Journals (Sweden)

    Nádia Valéria Mussi de Mira

    2008-12-01

    Full Text Available Neste estudo, avaliaram-se a distribuição dos Compostos Fenólicos Totais (CFT e o perfil de ácidos fenólicos, presentes nas frações, solúvel e insolúvel de dez genótipos de arroz (Oryza sativa L. de pericarpo pigmentado e não pigmentado. Devido à sua elevada capacidade antioxidante, os compostos fenólicos vem sendo apontados como possíveis promotores da saúde. Grande parte corresponde aos ácidos fenólicos presentes no grão sob a forma solúvel (livre e conjugada e insolúvel (ligada. Na literatura há poucas informações sobre a contribuição dos compostos fenólicos ligados, cujos teores são costumeiramente subestimados. Os CFT foram quantificados pelo método de Folin-Ciocalteau, enquanto os ácidos fenólicos por RP-HPLC. Na fração solúvel dos genótipos pigmentados, os teores de CFT foram variáveis, mas, em média, 5,7 vezes maiores do que nos não pigmentados (média de 3468 e 602 µg eq. Ácido Ferúlico (AF/g arroz, respectivamente, principalmente devido à presença de antocianinas e proantocianidinas. Na fração insolúvel, os pigmentados apresentaram duas vezes mais CFT do que os não pigmentados (825 e 378 µg eq. AF/g arroz, respectivamente, provavelmente devido à retenção de antocianinas e proantocianidinas, mesmo após cinco extrações consecutivas. Dentre os ácidos fenólicos, o ácido ferúlico foi o principal componente em todos os genótipos estudados, exceto no arroz preto, no qual predominou o ácido protocatecóico.This study was conducted to evaluate the distribution of total phenolic compounds and phenolic acids in the soluble and insoluble fractions of 10 rice (Oryza sativa L. genotypes with pigmented or non-pigmented pericarp. These compounds were reported to exert beneficial effects on human health due to their high antioxidant activities. The total phenolic compounds (CFT in both fractions was determined by the Folin-Ciocalteau method and phenolic acids RP-HPLC with Diode-Array Detection

  13. Seasonal and inter-annual variation in ecosystem scale methane emission from a boreal fen

    Science.gov (United States)

    Rinne, Janne; Li, Xuefei; Raivonen, Maarit; Peltola, Olli; Sallantaus, Tapani; Haapanala, Sami; Smolander, Sampo; Alekseychik, Pavel; Aurela, Mika; Korrensalo, Aino; Mammarella, Ivan; Tuittila, Eeva-Stiina; Vesala, Timo

    2016-04-01

    Northern wetlands are one of the major sources of atmospheric methane. We have measured ecosystem scale methane emissions from a boreal fen continuously since 2005. The site is an oligotrophic fen in boreal vegetation zone situated in Siikaneva wetland complex in Southern Finland. The mean annual temperature in the area is 3.3°C and total annual precipitation 710 mm. We have conducted the methane emission measurements by the eddy covariance method. Additionally we have measured fluxes of carbon dioxide, water vapor, and sensible heat together with a suite of other environmental parameters. We have analyzed this data alongside with a model run with University of Helsinki methane model. The measured fluxes show generally highest methane emission in late summers coinciding with the highest temperatures in saturated peat zone. During winters the fluxes show small but detectable emission despite the snow and ice cover on the fen. More than 90% of the annual methane emission occurs in snow-free period. The methane emission and peat temperature are connected in exponential manner in seasonal scales, but methane emission does not show the expected behavior with water table. The lack of water table position dependence also contrasts with the spatial variation across microtopography. There is no systematic variation in sub-diurnal time scale. The general seasonal cycle in methane emission is captured well with the methane model. We will show how well the model reproduces the temperature and water table position dependencies observed. The annual methane emission is typically around 10 gC m-2. This is a significant part of the total carbon exchange between the fen and the atmosphere and about twice the estimated carbon loss by leaching from the fen area. The inter-annual variability in the methane emission is modest. The June-September methane emissions from different years, comprising most of the annual emission, correlates positively with peat temperature, but not with

  14. Caracterização da conversão metabólica de ácidos fenólicos em fenóis voláteis por Brettanomyces/Dekkera = Characterization of the metabolic conversion of phenolic acids to volatile phenols by Brettanomyces/Dekkera

    OpenAIRE

    Gomes, Joana Lousada

    2012-01-01

    A acumulação de fenóis voláteis em vinhos tem causado grande preocupação na enologia moderna, sendo considerado, nos dias de hoje, um ponto-chave no controlo da qualidade dos vinhos. Os vinilfenóis (4-vinilfenol e 4-vinilguaiacol) e etilfenóis (4- etilfenol e 4-etilguaiacol) podem ser produzidos nos vinhos na sequência de atividade microbiana dando origem a odores e sabores indesejados geralmente descritos como “couro”, “suor de cavalo”, “animal” e “medicinal”. A origem exata d...

  15. Hydrological landscape settings of base-rich fen mires and fen meadows : an overview

    NARCIS (Netherlands)

    Grootjans, A.P.; Adema, E.B.; Bleuten, W.; Joosten, H.; Madaras, M.; Janáková, M.; Middleton, B.

    2006-01-01

    Question: Why do similar fen meadow communities occur in different landscapes? How does the hydrological system sustain base-rich fen mires and fen meadows? Location: Interdunal wetlands and heathland pools in The Netherlands, percolation mires in Germany, Poland, and Siberia, and calcareous spring

  16. Effect of Groundwater Abstraction on Fen Ecosystems

    DEFF Research Database (Denmark)

    Johansen, Ole; Pedersen, Morten Lauge; Jensen, Jacob Birk

    2011-01-01

    and spring habitats. Continuous water level data from deep and shallow wells in the fens reflect the hydrological conditions. Large differences in water level drawdown during dry summer periods have been observed in the monitored fens and it is hypothesised, that these differences are directly related...... of the monitored ecosystems and the response towards groundwater abstraction and forms a solid foundation for hydrological modelling....

  17. Actividad antioxidante, compuestos fenólicos y ácido ascórbico de frutillas en dos sistemas de producción Antioxidant activity, phenolic compounds and ascorbic acid content in strawberries from two crop production systems

    Directory of Open Access Journals (Sweden)

    Rufino Fernando F Cantillano

    2012-12-01

    Full Text Available El objetivo de este trabajo fue determinar la influencia del sistema de producción y del período de almacenamiento de frutillas sobre la pérdida de masa, compuestos fenólicos totales, antocianinas totales, ácido ascórbico (vitamina C, actividad antioxidante y sus correlaciones. En este experimento fueron utilizadas frutillas 'Camarosa' y 'Camino Real' con madurez comercial, procedentes de cultivos en sistemas de producción orgánico y convencional, localizados en el municipio de Pelotas-RS. Los frutos fueron almacenados durante 0, 2, 5 y 8 días a 1ºC y 90-95% de HR. En general, el contenido de fenoles totales, de antocianinas totales y la actividad antioxidante aumentaron durante el almacenamiento refrigerado, mientras que los contenidos de ácido ascórbico y de masa fresca disminuyeron significativamente. Los contenidos de fenoles totales y de antocianinas totales presentaron correlación positiva con la actividad antioxidante, siendo la correlación con el contenido de ácido ascórbico negativa. Las frutillas producidas en sistema orgánico y conservadas durante cinco días, mostraron mayores valores de actividad antioxidante. Después de ocho días de almacenamiento a 1ºC, los frutos del sistema de producción orgánico presentaron menor degradación de antocianinas y de ácido ascórbico que los frutos del sistema de producción convencional.The aim of this study was to determine the influence of the crop production system and storage period on weight loss, total phenolic content, total anthocyanin content, ascorbic acid (vitamin C content, and antioxidant activity in strawberries, as well as their correlations. For this experiment, strawberry fruits of 'Camarosa' and 'Camino Real' at commercial maturity from both organic and conventional crop production systems located in Pelotas, Brazil, were used. The fruits were cold stored for 0, 2, 5, and 8 days at 1ºC and 90-95% RH. In general the total phenolic, total anthocyanin levels

  18. Avaliação da atividade antioxidante e identificação dos ácidos fenólicos presentes no bagaço de maçã cv. Gala Evaluation of antioxidant activity and identification of phenolic acids present in the pomace of Gala variety apples

    Directory of Open Access Journals (Sweden)

    Marcia Soares

    2008-09-01

    Full Text Available No processamento da maçã para obtenção do suco, ocorre a formação de uma elevada quantidade de resíduo, representado pelas cascas e sementes, no qual são encontradas diversas substâncias, como os compostos fenólicos, aos quais são atribuídas as propriedades antioxidantes. Este estudo teve como objetivo avaliar o conteúdo de compostos fenólicos totais e a atividade antioxidante in vitro de extratos e frações de ácidos fenólicos livres, esterificadas solúveis e esterificadas insolúveis, obtidos por diferentes solventes, a partir do resíduo da maçã cv. Gala pelos métodos DPPH (2,2-difenil-1-picrilhidrazilo e ABTS [2,2'-azino-bis (3-etilbenzotiazolin 6-ácido sulfônico], além da identificação dos ácidos fenólicos por cromatografia gasosa. O sistema acetona 75% (v/v em água foi mais eficaz na extração dos compostos fenólicos totais. A atividade antioxidante neste extrato foi 4,83 e 25,46 µmol TEAC.g-1 de amostra com o método ABTS e de 7,43 e 39,15 µmol TEAC.g-1 pelo método DPPH, expressos em base úmida e seca, respectivamente. O teor de flavanóis foi 11,05 e 58,20 mg.100 g-1 em base úmida e seca, respectivamente. Houve uma correlação positiva entre o conteúdo de fenólicos totais e atividade antioxidante (r² = 0,9283. Foram identificados os ácidos fenólicos salícilico, gálico, propilgalato e sináptico nas três frações avaliadas, o primeiro estando presente em maior concentração em todas as frações estudadas. Os resultados indicam o potencial antioxidante do bagaço de maçã.Apple processing to obtain juice produces a great amount of discarded material constituted by peel and seed. Several substances, including phenolic compounds, to which antioxidant activity is attributed, are found in these fractions. This work aimed at evaluating total phenolic compounds and in vitro antioxidant activity of extracts and phenolic fractions (free, soluble esterified and insoluble esterified of apple, cv. Gala

  19. Método para a Determinação de Ácidos Fenólicos na Parede Celular de Forragens Method for Phenolic Acid Determination in Forage Cell Wall

    OpenAIRE

    Francisco Carlos Deschamps; Luiz Pereira Ramos

    2002-01-01

    Há fatores que limitam a digestão das forragens tropicais e estão associados à dinâmica dos ácidos fenólicos da parede celular. Os estudos destes compostos em forragens podem ser facilitados pela disponibilidade de métodos sensíveis que permitam o processamento de grande número de amostras. No presente trabalho, descreve-se um método para a determinação de ácidos fenólicos na parede celular de forragens, utilizando cromatografia líquida de alta eficiência (CLAE). Bagaço de cana, capim-elefant...

  20. Emissions of biogenic sulfur gases from northern bogs and fens

    Science.gov (United States)

    Demello, William Zamboni; Hines, Mark E.; Bayley, Suzanne E.

    1992-01-01

    Sulfur gases are important components of the global cycle of S. They contribute to the acidity of precipitation and they influence global radiation balance and climate. The role of terrestrial sources of biogenic S and their effect on atmospheric chemistry remain as major unanswered questions in our understanding of the natural S cycle. The role of northern wetlands as sources and sinks of gaseous S by measuring rates of S gas exchange as a function of season, hydrologic conditions, and gradients in tropic status was investigated. Experiments were conducted in wetlands in New Hampshire, particularly a poor fen, and in Mire 239, a poor fen at the Experimental Lakes Area (ELA) in Ontario. Emissions were determined using Teflon enclosures, gas cryotrapping methods and gas chromatography (GC) with flame photometric detection. Dynamic (sweep flow) and static enclosures were employed which yielded similar results. Dissolved S gases and methane were determined by gas stripping followed by GC.

  1. Modelling hydrological management for the restoration of acidified floating fens

    Science.gov (United States)

    Dekker, Stefan C.; Barendregt, Aat; Bootsma, Margien C.; Schot, Paul P.

    2005-12-01

    Wetlands show a large decline in biodiversity. To protect and restore this biodiversity, many restoration projects are carried out. Hydrology in wetlands controls the chemical and biological processes and may be the most important factor regulating wetland function and development. Hydrological models may be used to simulate these processes and to evaluate management scenarios for restoration. HYDRUS2D, a combined saturated-unsaturated groundwater flow and transport model, is presented. This simulates near-surface hydrological processes in an acidified floating fen, with the aim to evaluate the effect of hydrological restoration in terms of conditions for biodiversity. In the acidified floating fen in the nature reserve Ilperveld (The Netherlands), a trench system was dug for the purpose of creating a runoff channel for acid rainwater in wet periods and to enable circum-neutral surface water to enter the fen in dry periods. The model is calibrated against measured conductivity values for a 5 year period. From the model simulations, it was found that lateral flow in the floating raft is limited. Furthermore, the model shows that the best management option is a combination of trenches and inundation, which gave the best soil water quality in the root zone. It is concluded that hydrological models can be used for the calculation of management scenarios in restoration projects. The combined saturated-unsaturated model concept used in this paper is able to incorporate the governing hydrological processes in the wetland root zones. Copyright

  2. Actividad antioxidante, compuestos fenólicos y ácido ascórbico de frutillas en dos sistemas de producción Antioxidant activity, phenolic compounds and ascorbic acid content in strawberries from two crop production systems

    OpenAIRE

    Rufino Fernando F Cantillano; Julia Maria M Ávila; Maria do Carmo R Peralba; Tânia Mara Pizzolato; Ricardo P Toralles

    2012-01-01

    El objetivo de este trabajo fue determinar la influencia del sistema de producción y del período de almacenamiento de frutillas sobre la pérdida de masa, compuestos fenólicos totales, antocianinas totales, ácido ascórbico (vitamina C), actividad antioxidante y sus correlaciones. En este experimento fueron utilizadas frutillas 'Camarosa' y 'Camino Real' con madurez comercial, procedentes de cultivos en sistemas de producción orgánico y convencional, localizados en el municipio de Pelotas-RS. L...

  3. Biodiversity management of fens and fen meadows by grazing, cutting and burning

    NARCIS (Netherlands)

    Middleton, Beth A.; Holsten, Bettina; van Diggelen, Rudy

    2006-01-01

    Question: Can the biodiversity of fens in Europe and North America be maintained through the use of grazing (especially cattle grazing), fire, and/or cutting? Location: European and North American fens. Methods: This paper is a review of the literature on the effects of grazing, fire and cutting on

  4. The complex logic of stringent response regulation in Caulobacter crescentus: starvation signalling in an oligotrophic environment.

    Science.gov (United States)

    Boutte, Cara C; Crosson, Sean

    2011-05-01

    Bacteria rapidly adapt to nutritional changes via the stringent response, which entails starvation-induced synthesis of the small molecule, ppGpp, by RelA/SpoT homologue (Rsh) enzymes. Binding of ppGpp to RNA polymerase modulates the transcription of hundreds of genes and remodels the physiology of the cell. Studies of the stringent response have primarily focused on copiotrophic bacteria such as Escherichia coli; little is known about how stringent signalling is regulated in species that live in consistently nutrient-limited (i.e. oligotrophic) environments. Here we define the input logic and transcriptional output of the stringent response in the oligotroph, Caulobacter crescentus. The sole Rsh protein, SpoT(CC), binds to and is regulated by the ribosome, and exhibits AND-type control logic in which amino acid starvation is a necessary but insufficient signal for activation of ppGpp synthesis. While both glucose and ammonium starvation upregulate the synthesis of ppGpp, SpoT(CC) detects these starvation signals by two independent mechanisms. Although the logic of stringent response control in C. crescentus differs from E. coli, the global transcriptional effects of elevated ppGpp are similar, with the exception of 16S rRNA transcription, which is controlled independently of spoT(CC). This study highlights how the regulatory logic controlling the stringent response may be adapted to the nutritional niche of a bacterial species.

  5. Plankton networks driving carbon export in the oligotrophic ocean.

    Science.gov (United States)

    Guidi, Lionel; Chaffron, Samuel; Bittner, Lucie; Eveillard, Damien; Larhlimi, Abdelhalim; Roux, Simon; Darzi, Youssef; Audic, Stephane; Berline, Léo; Brum, Jennifer R; Coelho, Luis Pedro; Espinoza, Julio Cesar Ignacio; Malviya, Shruti; Sunagawa, Shinichi; Dimier, Céline; Kandels-Lewis, Stefanie; Picheral, Marc; Poulain, Julie; Searson, Sarah; Stemmann, Lars; Not, Fabrice; Hingamp, Pascal; Speich, Sabrina; Follows, Mick; Karp-Boss, Lee; Boss, Emmanuel; Ogata, Hiroyuki; Pesant, Stephane; Weissenbach, Jean; Wincker, Patrick; Acinas, Silvia G; Bork, Peer; de Vargas, Colomban; Iudicone, Daniele; Sullivan, Matthew B; Raes, Jeroen; Karsenti, Eric; Bowler, Chris; Gorsky, Gabriel

    2016-04-28

    The biological carbon pump is the process by which CO2 is transformed to organic carbon via photosynthesis, exported through sinking particles, and finally sequestered in the deep ocean. While the intensity of the pump correlates with plankton community composition, the underlying ecosystem structure driving the process remains largely uncharacterized. Here we use environmental and metagenomic data gathered during the Tara Oceans expedition to improve our understanding of carbon export in the oligotrophic ocean. We show that specific plankton communities, from the surface and deep chlorophyll maximum, correlate with carbon export at 150 m and highlight unexpected taxa such as Radiolaria and alveolate parasites, as well as Synechococcus and their phages, as lineages most strongly associated with carbon export in the subtropical, nutrient-depleted, oligotrophic ocean. Additionally, we show that the relative abundance of a few bacterial and viral genes can predict a significant fraction of the variability in carbon export in these regions.

  6. Oligotrophic Bacteria Enhance Algal Growth under Iron-Deficient Conditions

    OpenAIRE

    Keshtacher-Liebso..., E.; Hadar, Y; Chen, Y.

    1995-01-01

    A Halomonas sp., a marine halophilic and oligotrophic bacterium, was grown on exudates of Dunaliella bardawil. The bacteria increased the solubility of Fe, thereby enhancing its availability to the algae. As a result, the algal growth rate increased. Because of these syntrophic relations, growth of the marine alga D. bardawil was facilitated at Fe levels that would otherwise induce Fe deficiency and inhibit algal growth.

  7. Picocyanobacteria success in oligotrophic lakes: fact or fiction?

    Directory of Open Access Journals (Sweden)

    Cristiana CALLIERI

    2000-02-01

    Full Text Available Two approaches may be utilized to explain the predominance of picocyanobacteria (Pcy in oligotrophic lakes: the analysis of their interannual evolution in one single lake and their relative importance in different lakes along a trophic gradient. Here we discuss results from field data on picocyanobacteria over several seasons from a deep oligotrophic subalpine lake - Lago Maggiore, and variables influencing their abundance. Comparing data from lakes along a trophic gradient, no simple relationship emerges between lake’s trophic state and picocyanobacteria abundance and contribution to total phytoplanktonic biomass. That is, trophic state alone cannot explain the success/absence of picocyanobacteria that appear to be favored under P limitation, but seem more sensitive to grazing pressure and light. In some oligotrophic lakes, if light climate, grazing, and competition are favorable, picocyanobacteria can grow rapidly, out-compete competitors and become very abundant, but there are a host of factors that can influence the outcome of this competition, and ultimately influence Pcy success in lakes of all trophic types.

  8. Conservation and Biodiversity of Rich Fens

    DEFF Research Database (Denmark)

    Andersen, Dagmar Kappel

    2014-01-01

    Rich fen is a habitat type dependent on a constant supply of nutrient poor, calcium rich groundwater. A high, stable groundwater table, relatively high pH combined with nutrient poor conditions support a special and very species rich vegetation including many rare and threatened plant species. In...

  9. Ammonia-Oligotrophic and Diazotrophic Heavy Metal-Resistant Serratia liquefaciens Strains from Pioneer Plants and Mine Tailings.

    Science.gov (United States)

    Zelaya-Molina, Lily X; Hernández-Soto, Luis M; Guerra-Camacho, Jairo E; Monterrubio-López, Ricardo; Patiño-Siciliano, Alfredo; Villa-Tanaca, Lourdes; Hernández-Rodríguez, César

    2016-08-01

    Mine tailings are man-made environments characterized by low levels of organic carbon and assimilable nitrogen, as well as moderate concentrations of heavy metals. For the introduction of nitrogen into these environments, a key role is played by ammonia-oligotrophic/diazotrophic heavy metal-resistant guilds. In mine tailings from Zacatecas, Mexico, Serratia liquefaciens was the dominant heterotrophic culturable species isolated in N-free media from bulk mine tailings as well as the rhizosphere, roots, and aerial parts of pioneer plants. S. liquefaciens strains proved to be a meta-population with high intraspecific genetic diversity and a potential to respond to these extreme conditions. The phenotypic and genotypic features of these strains reveal the potential adaptation of S. liquefaciens to oligotrophic and nitrogen-limited mine tailings with high concentrations of heavy metals. These features include ammonia-oligotrophic growth, nitrogen fixation, siderophore and indoleacetic acid production, phosphate solubilization, biofilm formation, moderate tolerance to heavy metals under conditions of diverse nitrogen availability, and the presence of zntA, amtB, and nifH genes. The acetylene reduction assay suggests low nitrogen-fixing activity. The nifH gene was harbored in a plasmid of ∼60 kb and probably was acquired by a horizontal gene transfer event from Klebsiella variicola. PMID:27138047

  10. Organic nutrient enrichment in the oligotrophic ocean: Impacts on remineralization, carbon sequestration, and community structure

    Science.gov (United States)

    Mackey, K. R.; Paytan, A.; Post, A. F.

    2007-12-01

    In oligotrophic seas where inorganic nitrogen (N) and phosphorus (P) are below the limits of detection, organic forms of these nutrients may constitute greater than 90% of the total N and P in the euphotic zone. The combined enzymatic activity of phytoplankton and heterotrophic bacteria determines the rate of nutrient remineralization, thereby influencing phytoplankton growth rates and carbon sequestration in these regions. In this study we investigated the effects of fertilization with ammonium (NH4), nitrate (NO3), nitrite (NO2), and phosphate (PO4) as well as various forms of organic N (urea, glycine) and P (deoxyribonucleic acid, 2- aminoethyl phosphonic acid, phytic acid) on the growth and taxonomic composition of the phytoplankton community in the Gulf of Aqaba, Red Sea. The impacts of these changes on nutrient cycling and biological assimilation were also assessed. Organic N additions led to phytoplankton growth when given together with PO4, yielding 2-3 fold increases in chlorophyll a (Chl a) and cell density relative to initial levels. Moreover, our results show that addition of NH4 or NO3 led to accumulation of extra-cellular NO2, suggesting that incomplete assimilatory reduction of NO3 by phytoplankton as well as chemoautotrophic oxidation of NH4 by ammonium oxidizing microbes contributed to NO2 formation. These findings conflict with earlier studies in the Gulf that attributed NO2 formation solely to the phytoplankton community. Organic P additions also led to 2-3 fold increases in Chl a and cell density relative to initial levels when given together with NH4 and NO3. Compared to other P additions, DNA led to the rapid accumulation of extra-cellular PO4, indicating substantial nucleotidase activity in excess of the amount needed to meet phytoplankton growth requirements. These results show the importance and interconnectivity of phytoplankton and heterotrophic bacteria communities in contributing to nutrient cycling and carbon sequestration in

  11. Characteristics and ontogeny of oligotrophic hardwater lakes in the Forsmark area, central Sweden

    International Nuclear Information System (INIS)

    colonise the littoral, and a mire is formed around the lake. In later stages of succession, Sphagnum becomes more and more dominant in the system, which successively turns acidic. The final stage of the ontogeny is likely to be a raised bog ecosystem with an autonomous hydrological functioning. A tentative model for a mature hardwater lake has been created, indicating how and where substances from the drainage area may be accumulated in the system. Depending on the (unknown) hydrology of the lake basin, accumulation of substances can either take place in the Sphagnum littoral, in the illuminated soft-bottom sediments or in both these habitats. Processes in the open water will be of less importance in the system, since production of organisms in that habitat is most likely low. However, fish may act as a pump for nutrients and organic matter between the soft-bottom and the open water habitats, thereby disturbing the accumulation of substances in the sediments. In conclusion, several pieces are lacking to complete the picture of the structure and functioning of the ecosystem in the oligotrophic hardwater lakes of the Forsmark area. Research directed towards the understanding of the lakes as a trap for contaminants should be focused on the hydrology of the basin and on the basal production in two of the key habitats; the mire/floating littoral system and the 'microbial mat' in the light exposed soft bottom areas

  12. Characteristics and ontogeny of oligotrophic hardwater lakes in the Forsmark area, central Sweden

    Energy Technology Data Exchange (ETDEWEB)

    Brunberg, A.K.; Blomqvist, P. [Uppsala Univ. (Sweden). Dept. of Limnology

    1999-12-01

    colonise the littoral, and a mire is formed around the lake. In later stages of succession, Sphagnum becomes more and more dominant in the system, which successively turns acidic. The final stage of the ontogeny is likely to be a raised bog ecosystem with an autonomous hydrological functioning. A tentative model for a mature hardwater lake has been created, indicating how and where substances from the drainage area may be accumulated in the system. Depending on the (unknown) hydrology of the lake basin, accumulation of substances can either take place in the Sphagnum littoral, in the illuminated soft-bottom sediments or in both these habitats. Processes in the open water will be of less importance in the system, since production of organisms in that habitat is most likely low. However, fish may act as a pump for nutrients and organic matter between the soft-bottom and the open water habitats, thereby disturbing the accumulation of substances in the sediments. In conclusion, several pieces are lacking to complete the picture of the structure and functioning of the ecosystem in the oligotrophic hardwater lakes of the Forsmark area. Research directed towards the understanding of the lakes as a trap for contaminants should be focused on the hydrology of the basin and on the basal production in two of the key habitats; the mire/floating littoral system and the 'microbial mat' in the light exposed soft bottom areas.

  13. Biosorption of Metallic Elements onto Fen Peat

    Science.gov (United States)

    Krumins, Janis; Robalds, Artis

    2014-12-01

    Industrial development and anthropogenic activity have a huge impact on the environment, forcing society to find new and cost-effective environment treatment technologies. One of the most effective and environmentally friendly methods is the use of biosorbents, for which peat is one of the most cost-effective materials. The adsorption capabilities of peat sediments are well known; however, mainly raised bog peat is used for environmental treatment, and thus the abilities of fen peat are underestimated. The aim of this research was to assess the fen peat suitability as an adsorbent for metallic elements. In this study we have determined the sorption characteristics of Ca, Mg, K, Na, Cu and Pb and results show that fen peat deposits have a huge variability as a biosorbent due to their variable botanical composition and complex properties, for instance, under equal conditions, wood-sedge peat can have higher lead adsorption capacity than wood peat. However, due to its natural content of metallic elements, the sorption capacity overall is lower than it is for raised bog peat, although the high pH reaction encourage a high mobility metals.

  14. Lake level fluctuations boost toxic cyanobacterial "oligotrophic blooms".

    Directory of Open Access Journals (Sweden)

    Cristiana Callieri

    Full Text Available Global warming has been shown to strongly influence inland water systems, producing noticeable increases in water temperatures. Rising temperatures, especially when combined with widespread nutrient pollution, directly favour the growth of toxic cyanobacteria. Climate changes have also altered natural water level fluctuations increasing the probability of extreme events as dry periods followed by heavy rains. The massive appearance of Dolichospermum lemmermannii ( = planktonic Anabaena, a toxic species absent from the pelagic zone of the subalpine oligotrophic Lake Maggiore before 2005, could be a consequence of the unusual fluctuations of lake level in recent years. We hypothesized that these fluctuations may favour the cyanobacterium as result of nutrient pulses from the biofilms formed in the littoral zone when the lake level is high. To help verify this, we exposed artificial substrates in the lake, and evaluated their nutrient enrichment and release after desiccation, together with measurements of fluctuations in lake level, precipitation and D. lemmermannii population. The highest percentage of P release and the lowest C:P molar ratio of released nutrients coincided with the summer appearance of the D. lemmermannii bloom. The P pulse indicates that fluctuations in level counteract nutrient limitation in this lake and it is suggested that this may apply more widely to other oligotrophic lakes. In view of the predicted increase in water level fluctuations due to climate change, it is important to try to minimize such fluctuations in order to mitigate the occurrence of cyanobacterial blooms.

  15. Exploring Microbial Life in Oxic Sediments Underlying Oligotrophic Ocean Gyres

    Science.gov (United States)

    Ziebis, W.; Orcutt, B.; Wankel, S. D.; D'Hondt, S.; Szubin, R.; Kim, J. N.; Zengler, K.

    2015-12-01

    Oxygen, carbon and nutrient availability are defining parameters for microbial life. In contrast to organic-rich sediments of the continental margins, where high respiration rates lead to a depletion of O2 within a thin layer at the sediment surface, it was discovered that O2 penetrates several tens of meters into organic-poor sediments underlying oligotrophic ocean gyres. In addition, nitrate, another important oxidant, which usually disappears rapidly with depth in anoxic sediments, tends to accumulate above seawater concentrations in the oxic subsurface, reflecting the importance of nitrogen cycling processes, including both nitrification and denitrification. Two IODP drilling expeditions were vital for exploring the nature of the deep subsurface beneath oligotrophic ocean gyres, expedition 329 to the South Pacific Gyre (SPG) and expedition 336 to North Pond, located on the western flank of the Mid-Atlantic ridge beneath the North Atlantic Gyre. Within the ultra-oligotrophic SPG O2 penetrates the entire sediment column from the sediment-water interface to the underlying basement to depths of > 75 m. At North Pond, a topographic depression filled with sediment and surrounded by steep basaltic outcrops, O2 penetrates deeply into the sediment (~ 30 m) until it eventually becomes depleted. O2 also diffuses upward into the sediment from seawater circulating within the young crust underlying the sediment, resulting in a deep oxic layer several meters above the basalt. Despite low organic carbon contents microbial cells persist throughout the entire sediment column within the SPG (> 75 m) and at North Pond, albeit at low abundances. We explored the nature of the subsurface microbial communities by extracting intact cells from large volumes of sediment obtained from drill cores of the two expeditions. By using CARD-FiSH, amplicon (16s rRNA) and metagenome sequencing we shed light on the phylogenetic and functional diversity of the elusive communities residing in the

  16. Molecular diversity of diazotrophs in oligotrophic tropical seagrass bed communities.

    Science.gov (United States)

    Bagwell, Christopher E; Rocque, Jeannine R; Smith, Garriett W; Polson, Shawn W; Friez, Michael J; Longshore, John W; Lovell, Charles R

    2002-02-01

    Denaturing gradient gel electrophoresis (DGGE) was employed to resolve PCR-amplified nifH sequences from vegetated and unvegetated sediments from two oligotrophic seagrass bed sites on San Salvador Island, Bahamas, in order to assess diazotroph species composition. All DGGE profiles from these sites showed the same prominent bands. These bands were sequenced, yielding 67 different nifH sequences, which were used in phylogenetic reconstructions. Most sequences were from anaerobes, but some were affiliated with the alpha- and (gamma-+beta-) Proteobacteria. Several NifH sequences were nearly identical to those from Azospirillum brasilense and Vibrio diazotrophicus. These seagrass bed sediments support a diverse diazotroph assemblage that is, at least superficially, similar to that associated with an intertidal grass (Spartina alterniflora).

  17. Efeito do tratamento térmico na concentração de carotenóides, compostos fenólicos, ácido ascórbico e capacidade antioxidante do suco de tangerina murcote Effect of thermal treatment on the carotenoid, phenolic compound and ascorbic acid concentrations, and the antioxidant capacity of murcott tangerine juice

    Directory of Open Access Journals (Sweden)

    André de Souza Dutra

    2012-09-01

    Full Text Available Neste estudo, avaliou-se o efeito do tratamento térmico do suco de tangerina murcote em relação ao teor de carotenóides totais, ao perfil de carotenóides (luteína, zeaxantina, β-criptoxantina e β-caroteno, aos compostos fenólicos totais, ao ácido ascórbico e à capacidade antioxidante. No processo, utilizou-se um trocador de calor tubular, sendo avaliados 11 tratamentos seguindo um ensaio fatorial completo 2² com três repetições no ponto central, com quatro pontos axiais e uma região de observação de 88 a 100 ºC e 16 a 44 s. O teor de caratenóides totais decresceu de forma significativa em quase todos os tratamentos aplicados, se comparado ao valor encontrado para o suco in natura. A maioria dos tratamentos não reduziu de forma significativa os teores dos caratenóides luteína, zeaxantina e β-criptoxantina. Além disso, o teor de β-caroteno não sofreu alterações significativas em todos os tratamentos avaliados. A análise de variância mostrou que, para os caratenóides, não ocorreram interações significativas entre as variáveis temperatura e tempo. Os teores de ácido ascórbico e compostos fenólicos totais apresentaram reduções em seis condições avaliadas, ao passo que, em quatro, observou-se um aumento dos teores de compostos fenólicos totais, causado provavelmente pela evaporação da água presente no suco. A maior redução do teor de ácido ascórbico e o maior aumento para compostos fenólicos totais foi observado para o binômio 100 ºC/30 s. O teor de ácido ascórbico sofreu de forma significativa a influência da temperatura e esse processo de degradação pode ser descrito por meio de um modelo quadrático. Todos os tratamentos utilizados reduziram a capacidade antioxidante do suco, sendo mais intensa para o binômio 100 ºC/30 s. As variações observadas não alteraram de maneira considerável as características nutricionais do suco e os tratamentos térmicos realizados a 94 ºC por 16 a 44 s

  18. Extração, análise e distribuição dos ácidos fenólicos em genótipos pigmentados e não pigmentados de arroz (Oryza sativa L.) Extraction, analysis and distribution of phenolic acids in pigmented and non-pigmented genotypes of rice (Oryza sativa L.)

    OpenAIRE

    Nádia Valéria Mussi de Mira; Rosa Maria Cerdeira Barros; Moacir Antonio Schiocchet; José Alberto Noldin; Ursula Maria Lanfer-Marquez

    2008-01-01

    Neste estudo, avaliaram-se a distribuição dos Compostos Fenólicos Totais (CFT) e o perfil de ácidos fenólicos, presentes nas frações, solúvel e insolúvel de dez genótipos de arroz (Oryza sativa L.) de pericarpo pigmentado e não pigmentado. Devido à sua elevada capacidade antioxidante, os compostos fenólicos vem sendo apontados como possíveis promotores da saúde. Grande parte corresponde aos ácidos fenólicos presentes no grão sob a forma solúvel (livre e conjugada) e insolúvel (ligada). Na lit...

  19. Deep silicon maxima in the stratified oligotrophic Mediterranean Sea

    Directory of Open Access Journals (Sweden)

    Y. Crombet

    2011-02-01

    Full Text Available The silicon biogeochemical cycle has been studied in the Mediterranean Sea during late summer/early autumn 1999 and summer 2008. The distribution of nutrients, particulate carbon and silicon, fucoxanthin (Fuco, and total chlorophyll-a (TChl-a were investigated along an eastward gradient of oligotrophy during two cruises (PROSOPE and BOUM encompassing the entire Mediterranean Sea during the stratified period. At both seasons, surface waters were depleted in nutrients and the nutriclines gradually deepened towards the East, the phosphacline being the deepest in the easternmost Levantine basin. Following the nutriclines, parallel deep maxima of biogenic silica (DSM, fucoxanthin (DFM and TChl-a (DCM were evidenced during both seasons with maximal concentrations of 0.45 μmol L−1 for BSi, 0.26 μg L−1 for Fuco, and 1.70 μg L−1 for TChl-a, all measured during summer. Contrary to the DCM which was a persistent feature in the Mediterranean Sea, the DSM and DFMs were observed in discrete areas of the Alboran Sea, the Algero-Provencal basin, the Ionian sea and the Levantine basin, indicating that diatoms were able to grow at depth and dominate the DCM under specific conditions. Diatom assemblages were dominated by Chaetoceros spp., Leptocylindrus spp., Pseudonitzschia spp. and the association between large centric diatoms (Hemiaulus hauckii and Rhizosolenia styliformis and the cyanobacterium Richelia intracellularis was observed at nearly all sites. The diatom's ability to grow at depth is commonly observed in other oligotrophic regions and could play a major role in ecosystem productivity and carbon export to depth. Contrary to the common view that Si and siliceous phytoplankton are not major components of the Mediterranean biogeochemistry, we suggest here that diatoms, by persisting at depth during the stratified period, could contribute to a

  20. Short-Term Summer Inundation as a Measure to Counteract Acidification in Rich Fens.

    Directory of Open Access Journals (Sweden)

    Ivan S Mettrop

    Full Text Available In regions with intensive agriculture, water level fluctuation in wetlands has generally become constricted within narrow limits. Water authorities are, however, considering the re-establishment of fluctuating water levels as a management tool in biodiverse, base-rich fens ('rich fens'. This includes temporary inundation with surface water from ditches, which may play an important role in counteracting acidification in order to conserve and restore biodiversity. Inundation may result in an increased acid neutralizing capacity (ANC for two reasons: infiltration of base-rich inundation water into peat soils, and microbial alkalinity generation under anaerobic conditions. The main objectives of this study were to test whether short-term (2 weeks summer inundation is more effective than short-term winter inundation to restore the ANC in the upper 10 cm of non-floating peat soils, and to explain potential differences. Large-scale field experiments were conducted for five years in base-rich fens and Sphagnum-dominated poor fens. Winter inundation did not result in increased porewater ANC, because infiltration was inhibited in the waterlogged peat and evapotranspiration rates were relatively low. Also, low temperatures limit microbial alkalinity generation. In summer, however, when temperature and evapotranspiration rates are higher, inundation resulted in increased porewater Ca and HCO3- concentrations, but only in areas with characteristic rich fen bryophytes. This increase was not only due to stronger infiltration into the soil, but also to higher microbial alkalinity generation under anaerobic conditions. In contrast, porewater ANC did not increase in Sphagnum-plots as a result of the ability of Sphagnum spp. to acidify their environment. In both rich and poor fens, flooding-induced P-mobilization remained sufficiently low to safeguard P-limited vegetation. NO3(- and NH4(+ dynamics showed no considerable changes either. In conclusion, short

  1. Short-Term Summer Inundation as a Measure to Counteract Acidification in Rich Fens.

    Science.gov (United States)

    Mettrop, Ivan S; Cusell, Casper; Kooijman, Annemieke M; Lamers, Leon P M

    2015-01-01

    In regions with intensive agriculture, water level fluctuation in wetlands has generally become constricted within narrow limits. Water authorities are, however, considering the re-establishment of fluctuating water levels as a management tool in biodiverse, base-rich fens ('rich fens'). This includes temporary inundation with surface water from ditches, which may play an important role in counteracting acidification in order to conserve and restore biodiversity. Inundation may result in an increased acid neutralizing capacity (ANC) for two reasons: infiltration of base-rich inundation water into peat soils, and microbial alkalinity generation under anaerobic conditions. The main objectives of this study were to test whether short-term (2 weeks) summer inundation is more effective than short-term winter inundation to restore the ANC in the upper 10 cm of non-floating peat soils, and to explain potential differences. Large-scale field experiments were conducted for five years in base-rich fens and Sphagnum-dominated poor fens. Winter inundation did not result in increased porewater ANC, because infiltration was inhibited in the waterlogged peat and evapotranspiration rates were relatively low. Also, low temperatures limit microbial alkalinity generation. In summer, however, when temperature and evapotranspiration rates are higher, inundation resulted in increased porewater Ca and HCO3- concentrations, but only in areas with characteristic rich fen bryophytes. This increase was not only due to stronger infiltration into the soil, but also to higher microbial alkalinity generation under anaerobic conditions. In contrast, porewater ANC did not increase in Sphagnum-plots as a result of the ability of Sphagnum spp. to acidify their environment. In both rich and poor fens, flooding-induced P-mobilization remained sufficiently low to safeguard P-limited vegetation. NO3(-) and NH4(+) dynamics showed no considerable changes either. In conclusion, short-term summer inundation

  2. Zooplankton biomass dynamics in oligotrophic versus eutrophic conditions : a test of the PEG model

    OpenAIRE

    Straile, Dietmar

    2015-01-01

    1. The model of the International Society of Limnology (SIL) Plankton Ecology working group (hereafter the PEG model) is a verbal model describing the patterns and driving factors of seasonal phytoplankton and zooplankton succession in oligotrophic and eutrophic lakes (Sommer et al., 1986). Despite being a citation classic, tests of the PEG model with respect to differences in zooplankton biomass dynamics between oligotrophic and eutrophic lakes are lacking.2. Here, I use the long-term data f...

  3. CO dissociation on magnetic Fen clusters

    KAUST Repository

    Jedidi, Abdesslem

    2014-01-01

    This work theoretically investigates the CO dissociation on Fen nanoparticles, for n in the range of 1-65, focusing on size dependence in the context of the initial step of the Fischer-Tropsch reaction. CO adsorbs molecularly through its C-end on a triangular facet of the nanoparticle. Dissociation becomes easier when the cluster size increases. Then, the C atom is bonded to a square facet that is generated as a result of the adsorption if it does not yet exist in the bare cluster, while the O atom is adsorbed on a triangular facet. In the most stable situation, the two adsorbed atoms remain close together, both having in common one shared first-neighbor iron atom. There is a partial spin quenching of the neighboring Fe atoms, which become more positively charged than the other Fe atoms. The shared surface iron atom resembles a metal-cation from a complex. Despite the small size of the iron cluster considered, fluctuations due to specific configurations do not influence properties for n > 25 and global trends seem significant.

  4. Electronic structure and magnetism of equiatomic FeN

    OpenAIRE

    Kong, Yong

    2000-01-01

    In order to investigate the phase stability of equiatomic FeN compounds and the structure-dependent magnetic properties, the electronic structure and total energy of FeN with NaCl, ZnS and CsCl structures and various magnetic configurations are calculated using the first-principles TB-LMTO-ASA method. Among all the FeN phases considered, the antiferromagnetic NaCl structure with q=(00pi) is found to have the lowest energy at the theoretical equilibrium volume. However, the FM NaCl phase lies ...

  5. From groundwater abstraction to vegetative response in fen ecosystems

    DEFF Research Database (Denmark)

    Johansen, Ole Munch; Jensen, Jacob Birk; Pedersen, Morten Lauge

    2014-01-01

    hydrology. Fens are rare and threatened worldwide due to pressures from agriculture, to lack of appropriate management and to altered catchment hydrology. A solid foundation for hydrological modelling was established based on intensive monitoring at the site, combined with full-scale pumping tests...... periods. The predicted change in water table conditions in the fen habitat is compared to the variability found in 35 Danish fens, and the ecological response is discussed based on statistical water-level vegetation relations. The results provide a rare quantitative foundation for decision making...

  6. Life histories and seasonal dynamics of common boreal pelagic copepods (Crustacea, Copepoda inhabiting an oligotrophic Fennoscandian lake

    Directory of Open Access Journals (Sweden)

    Svein Birger WÆRVÅGEN

    2010-08-01

    Full Text Available The annual seasonal abundance and spatial distribution of four widespread pelagic copepods, the Palaeartic calanoid Eudiaptomus gracilis, the cyclopoids Mesocyclops leuckarti and Thermocyclops oithonoides, and the Holartic Cyclops scutifer were investigated in Lake Gjerstadvann, an oligotrophic boreal lake. Important ecological traits such as life cycles, pelagic microhabitats and wintering strategies varied strongly between the investigated copepods, and influenced seasonal succession in the plankton community. Fish predation did not seem to affect copepod abundances, except perhaps the two lage-sized, less abundant species, the Palaeartic calanoid Heterocope saliens and the Holartic cyclopoid Cyclops abyssorum. Life cycles varied from one (C. scutifer to three (M. leuckarti and E. gracilis complete generations per year, primarily related to habitat temperatures. Wintering took place as late instars (C. scutifer, C. abyssorum or cop V and adults (E. gracilis in the plankton, late instars in profundal (T. oithonoides or littoral (M. leuckarti sediment diapause, and embryonic diapause in sediment egg bank (H. saliens. C. scutifer and C. abyssorum exhibited delayed development in the profundal waters during winter, which could be characterised as so-called "active diapause". C. scutifer, T. oithonoides, and C. abyssorum in Lake Gjerstadvann were probably negatively affected by acidified waters. M. leuckarti seemed to be the most acid-tolerant of these species being able to endure pH slightly below 5.0, whereas T. oithonoides was usually absent at such pH levels. The calanoid species H. saliens and E. gracilis were extremely tolerant towards acidic environments. The yearly differences in population abundance as indicated by the fluctuations in the diapausing populations were probably due to environmental variations in water chemistry occurring during the most vulnerable ontogenetic stages, i.e., eggs and nauplii. Even if the pelagic ecosystem in

  7. Light, nutrients, and herbivore growth in oligotrophic streams

    Energy Technology Data Exchange (ETDEWEB)

    Hill, Walter R [ORNL; Smith, John G [ORNL; Stewart, Arthur J [ORNL

    2010-02-01

    The light : nutrient hypothesis posits that herbivore growth is increasingly constrained by low food quality as the ratio of light to nutrients increases in aquatic ecosystems. We tested predictions of this hypothesis by examining the effects of large seasonal cycles in light and nutrients on the mineral content of periphyton and the growth rate of a dominant herbivore (the snail Elimia clavaeformis) in two oligotrophic streams. Streambed irradiances in White Oak Creek and Walker Branch (eastern Tennessee, USA) varied dramatically on a seasonal basis due to leaf phenology in the surrounding deciduous forests and seasonal changes in sun angle. Concentrations of dissolved nutrients varied inversely with light, causing light : nitrate and light : phosphate to range almost 100-fold over the course of any individual year. Periphyton nitrogen and phosphorus concentrations were much lower than the concentrations of these elements in snails, and they bottomed out in early spring when streambed irradiances were highest. Snail growth, however, peaked in early spring when light:nutrient ratios were highest and periphyton nutrient concentrations were lowest, Growth was linearly related to primary production (accounting for up to 85% of growth variance in individual years), which in turn was driven by seasonal variation in light. Conceptual models of herbivore growth indicate that growth should initially increase as increasing light levels stimulate primary production, but then level off, and then decrease as the negative effects of decreasing algal nutrient content override the positive effects of increased food production. Our results showed no evidence of an inflection point where increasing ratios of light to nutrients negatively affected growth. Snail growth in these intensively grazed streams is probably unaffected by periphyton nutrient content because exploitative competition for food reduces growth rates to levels where the demand for nitrogen and phosphorus is small

  8. Characterization of Fen-Daqu Through Multivariate Statistical Analysis of H-1 NMR Spectroscopic Data

    NARCIS (Netherlands)

    Van-Diep, L.; Zheng, X.; Ma, K.; Chen, J.Y.; Han, B.Z.; Nout, M.J.R.

    2011-01-01

    J. Inst. Brew. 117(4), 516-522, 2011 Fen liquor is typical of Chinese light-flavour liquor (alcoholic spirit), which is fermented from sorghum with Fen-Daqu powder. Fen-Daqu is a saccharifying agent and fermentation starter in this fermentation process and in Fen traditional vinegar. To investigate

  9. Response of Mytilus edulis to enhanced phytoplankton availability by controlled upwelling in an oligotrophic fjord

    OpenAIRE

    Strohmeier, Tore; Strand, Oivind; ALUNNO-BRUSCIA, Marianne; Duinker, Arne; Rosland, Rune; Aure, Jan; Erga, Svein R.; Naustvoll, Lars J.; Jansen, Henrice M.; Cranford, Peter J.

    2015-01-01

    The controlled upwelling of nutrient-rich deep water in oligotrophic coastal regions has been proposed as a means of increasing phytoplankton and, subsequently, bivalve aquaculture production. This was tested as part of a large-scale upwelling experiment in an oligotrophic environment (Lysefjord, Norway). The mean chlorophyll a concentration in the upwelling area was consistently higher than at the control site (mean ± SD: 3.3 ± 1.9 and 1.5 ± 0.6 mg Chl a m-3, respectively) during the 4 mo of...

  10. Causes of change in nitrophytic and oligotrophic lichen species in a Mediterranean climate: Impact of land cover and atmospheric pollutants

    International Nuclear Information System (INIS)

    With the aim of determining the main drivers of changes in nitrophytic and oligotrophic macro-lichen communities in an industrial region with a Mediterranean climate, we considered both land-cover types and atmospheric pollutants. We determined the relation between the abundance of nitrophytic and oligotrophic species with environmental factors considering the distance of influence of land-cover types. The results showed that oligotrophic species decreased in the proximity of artificial areas, barren land and agricultural areas, associated with higher concentrations of NO2 and Zn, and Ti, probably dust of industrial and agricultural origin. Nitrophytic species were positively related to all the mentioned land-cover types, and with higher concentrations of Fe and N. Magnesium, probably from ocean aerosols, was negatively related to oligotrophic species and positively to nitrophytic. - Causes of change in nitrophytic and oligotrophic lichen species

  11. Ácidos fenólicos como antioxidantes

    OpenAIRE

    SOARES Sergio Eduardo

    2002-01-01

    Os compostos fenólicos têm sido muito estudados devido a sua influência na qualidade dos alimentos. Englobam uma gama enorme de substâncias, entre elas os ácidos fenólicos, os quais, por sua constituição química, possuem propriedades antioxidantes. Assim, a presente revisão procura reunir diversos estudos que avaliaram o potencial antioxidante dos ácidos fenólicos na conservação de alimentos lipídicos. Além disso, são reunidos também estudos sobre a ação antioxidante destes compostos no siste...

  12. Fenólicos totais e capacidade antioxidante in vitro de polpas de frutos tropicais

    Directory of Open Access Journals (Sweden)

    Luanne Morais Vieira

    2011-09-01

    Full Text Available O consumo de frutos e suas polpas tem sido muito recomendado por seu valor nutricional, alto teor de fibras, vitamina C e carotenoides. Trabalhos recentes têm apontado esses alimentos como fontes de compostos fenólicos com ação antioxidante, portanto sequestradores de radicais livres, com ação protetora contra o surgimento e/ou desenvolvimento de processos degenerativos que conduzem a doenças crônicas não transmissíveis. Devido à crescente comercialização e consumo de polpas de frutas no Brasil, especialmente na cidade de Teresina-Piauí, este trabalho selecionou um grupo de polpas de frutos de elevado consumo local para avaliação do teor de fenólicos totais e da atividade antioxidante in vitro pelo método de captura de radicais livres: DPPH (radical 1,1-diphenil-2-picrilhydrazil e ABTS (radical 2,2'azinobis(3-ethylbenzthiazoline-6-sulfonic acid. Os frutos selecionados foram: Acerola (Malpighia emarginata DC., Bacuri (Platonia insignis Mart., Cajá (Spondias mombin L., Caju (Anacardium occidentale, Goiaba(Psidium guajava e Tamarindo (Tamarindus indica L.. Os teores de fenólicos totais encontrados nas polpascongeladas destes frutos exibiram quantidades relevantes de polifenóis, destacando-se a polpa de acerola com 835,25 ± 32,44 e 449,63 ± 10,24 mg /100g nos extratos aquosos e hidroalcoólicos, respectivamente, seguido pela polpa de caju com 201,61 ± 19,15 e 165,07 ± 4,10 mg /100g. As polpas de bacuri e tamarindo foram as que apresentaram os menores teores de fenólicos totais. Com relação à atividade antioxidante in vitro, os melhores resultados foram encontrados para os extratos aquosos e hidroalcoólicos das polpas de acerola, caju e goiaba. A capacidade antioxidante destas polpas (EC50 em µg/mL variou de 24,42 a 413,36 e de 1,74 a 259,18 para os extratos aquosos e hidroalcoólicos, respectivamente. Utilizando o radical ABTS, a atividade antioxidante para essas mesmas polpas de frutas apresentou valores TEAC que

  13. The hydrological balance of a groundwater discharge fen

    Science.gov (United States)

    Boeye, D.; Verheyen, R. F.

    1992-08-01

    Linear regression analysis and weekly water level measurements were used to study the hydrological balance of a groundwater discharge fen. The main water flows pertain to rainfall, evapotranspiration, and groundwater discharge. Owing to the high water table in depressions, rainfall is transformed partly to direct runoff. This process depends on the landform of the study area and on the daily distribution of rainfall and evapotranspiration. During very dry summers, evaporation causes a drop in the water table. Such events may be important for plant life in the fen. Protection of the regional groundwater flow and regulation of the ditches are potential measures for hydrological management of the site.

  14. Brevibacterium siliguriense sp nov., a facultatively oligotrophic bacterium isolated from river water

    NARCIS (Netherlands)

    Kumar, A.; Ince, I.A.; Kati, A.; Chakraborty, R.

    2013-01-01

    A Gram-positive-staining, rod-shaped, facultatively oligotrophic bacterial strain, designated MB18(T), was isolated from a water sample collected from the River Mahananda at Siliguri (26 degrees 44' 23.20' N, 88 degrees 25' 22.89' a West-Bengal, India. On the basis of 16S rRNA gene sequence similari

  15. What drives seasonal change in oligotrophic area in the subtropical North Atlantic?

    Science.gov (United States)

    Dave, Apurva C.; Barton, Andrew D.; Lozier, M. Susan; McKinley, Galen A.

    2015-06-01

    The oligotrophic regions of the subtropical gyres cover a significant portion of the global ocean, and exhibit considerable but poorly understood intraseasonal, interannual, and longer-term variations in spatial extent. Here using historical observations of surface ocean nitrate, wind, and currents, we have investigated how horizontal and vertical supplies of nitrate control seasonal changes in the size and shape of oligotrophic regions of the subtropical North Atlantic. In general, the oligotrophic region of the subtropical North Atlantic is associated with the region of weak vertical supply of nitrate. Though the total vertical supply of nitrate here is generally greater than the total horizontal supply, we find that seasonal expansion and contraction of the oligotrophic region is consistent with changes in horizontal supply of nitrate. In this dynamic periphery of the subtropical gyre, the seasonal variations in chlorophyll are linked to variations in horizontal nitrate supply that facilitate changes in intracellular pigment concentrations, and to a lesser extent, phytoplankton biomass. Our results suggest that horizontal transports of nutrient are crucial in setting seasonal cycles of chlorophyll in large expanses of the subtropical North Atlantic, and may play a key and underappreciated role in regulating interannual variations in these globally important marine ecosystems.

  16. Anotaciones spbre algunos fenómenos del sistema nervioso

    OpenAIRE

    Llinás, Pablo A.

    2011-01-01

    Con todo respeto y por su apreciado conducto, me permito solicitar de la docta corporación que usted dignamente preside, su valioso concepto sobre algunas anotaciones relativas a la fisiología y a la fisiopatología de ciertos fenómenos del sistema nervioso.

  17. Preliminary palaeomagnetic results from the Fen carbonatite complex, S. Norway

    NARCIS (Netherlands)

    Poorter, R.P.E.

    1972-01-01

    Samples from a hematite carbonate rock of the Eocambrian-Lower Cambrian Fen carbonatite-alkaline rock complex in southern Norway, yield a stable NRM with a direction after magnetic cleaning of D = 205°, I = −56° (N = 19, (k = 138, α95 = 3°). This corresponds with a palaeomagnetic pole position at 63

  18. Light as an environmental filter in fen vegetation

    NARCIS (Netherlands)

    Kotowski, W; van Diggelen, R

    2004-01-01

    Questions: 1. To what extent does light availability differ among fen plant communities? 2. To what extent does light coincide with productivity and moisture gradients? 3. Does light act as an important environmental filter in natural and transformed riparian landscapes? Location: Current data from

  19. Silica cycling in the ultra-oligotrophic Eastern Mediterranean Sea

    Directory of Open Access Journals (Sweden)

    M. D. Krom

    2014-03-01

    Full Text Available Although silica is a key plant nutrient there have been few studies aimed at understanding the Si cycle in the Eastern Mediterranean Sea (EMS. Here we use a combination of new measurements and literature values to explain the silicic acid distribution across the basin and to calculate a silica budget to identify the key controlling processes. The surface water concentration of ~ 1 μM, which is unchanging seasonally across the basin was due to the inflow of Western Mediterranean Sea (WMS water at the Straits of Sicily. It does not change seasonally because there is only a sparse population of diatoms due to the low nutrient (N and P supply to the photic zone in the EMS. The concentration of silicic acid in the deep water of the western Ionian Sea (6.3 μM close to the S. Adriatic area of formation was due to the preformed silicic acid (3 μM plus biogenic silica (BSi from the dissolution of diatoms from the winter phytoplankton bloom (3.2 μM. The increase of 4.4 μM across the deep water of the EMS was due to silicic acid formed from in-situ diagenetic weathering of alumina-silicate minerals fluxing out of the sediment. The major inputs to the EMS are silicic acid and BSi inflowing from the western Mediterranean (121 × 109 mol Si year−1 silicic acid and 16 × 109 mol Si year−1 BSi, silicic acid fluxing from the sediment (54 × 109 mol Si year−1, riverine (27 × 109 mol Si year−1 and subterranean ground water (9.7 × 109 mol Si year−1 inputs, with only a minor direct input from dissolution of dust in the water column (1 × 109 mol Si year−1. This budget shows the importance of rapidly dissolving BSi and in-situ weathering of alumino-silicate minerals as sources of silica to balance the net export of silicic acid at the Straits of Sicily. Future measurements to improve the accuracy of this preliminary budget have been identified.

  20. Impacts of short-term droughts and inundations in species-rich fens during summer and winter: Large-scale field manipulation experiments

    NARCIS (Netherlands)

    C. Cusell; I.S. Mettrop; E.E. van Loon; L.P.M. Lamers; M. Vorenhout; A.M. Kooijman

    2015-01-01

    For the conservation and restoration of biodiverse rich fens, base-rich and nutrient-poor conditions are vital. In wetlands with artificially stable surface water levels, the re-introduction of temporary water level fluctuations has been postulated to restore the acid neutralizing capacity (ANC) of

  1. Species trait shifts in vegetation and soil seed bank during fen degradation

    NARCIS (Netherlands)

    Klimkowska, A.; Bekker, R.M.; Diggelen, R.; Kotowski, W.

    2010-01-01

    Fens in Central Europe are characterised by waterlogged organic substrate and low productivity. Human-induced changes due to drainage and mowing lead to changes in plant species composition from natural fen communities to fen meadows and later to over-drained, degraded meadows. Moderate drainage lea

  2. Characterization of volatile compounds in Fen-Daqu - a traditional Chinese liquor fermentation starter

    NARCIS (Netherlands)

    Van-Diep, L.; Zheng, X.; Chen, J.Y.; Han, B.Z.

    2012-01-01

    Fen-Daqu is a saccharifying agent and fermentation starter for the production of Chinese liquor Fen (alcoholic spirit) and Fen traditional vinegar. The volatile compounds produced at seven incubation steps were analysed by HS-SPME-GC-MS. A total of 83 major volatile compounds were identified, includ

  3. Eddy-entrained Pearl River plume into the oligotrophic basin of the South China Sea

    Science.gov (United States)

    He, Xianqiang; Xu, Dongfeng; Bai, Yan; Pan, Delu; Chen, Chen-Tung Arthur; Chen, Xiaoyan; Gong, Fang

    2016-08-01

    The South China Sea (SCS) is the world's largest tropical marginal sea with an oligotrophic basin. In June 2015, a rare large phytoplankton bloom, which is ~500 km long, 100 km wide and lasting more than 19 days, was captured in the northern SCS basin by satellite daily chlorophyll images. Water within the bloom area had a feature of low salinity and high temperature measured by an accidental-passing cruise. Meanwhile, satellite sea level anomaly images and drifter trajectory proved there was a cyclonic eddy nearby. No typhoon and heavy rain happened in this period, so we believed the bloom was triggered by the injection of nutrient-rich Pearl River plume driven by eddy. This is the first report on eddy-entrained Pearl River plume into the SCS, which would raise a new view on irregular transportation of nutrient and carbon and its related biogeochemical influence on the oligotrophic ocean.

  4. Specific-activity and concentration model applied to cesium movement in an oligotrophic lake

    International Nuclear Information System (INIS)

    A linear systems-analysis model was derived to simulate the time-dependent dynamics of specific activity and concentration of radionuclides in aquatic systems. Transfer coefficients were determined for movement of 137Cs in the components of an oligotrophic lake. These coefficients were defined in terms of basic environmental and ecological data so that the model can be applied to a wide variety of sites. Simulations with a model that ignored sediment--water interactions predicted much higher 137Cs specific activities in the lake water and biota than did those with the complete model. Comparing 137Cs concentrations predicted by the model with concentrations reported for the biota of an experimentally contaminated oligotrophic lake indicated that the transfer coefficients derived for the biota are adequate

  5. Parallel Evolution and Horizontal Gene Transfer of the pst Operon in Firmicutes from Oligotrophic Environments

    Directory of Open Access Journals (Sweden)

    Alejandra Moreno-Letelier

    2011-01-01

    Full Text Available The high affinity phosphate transport system (pst is crucial for phosphate uptake in oligotrophic environments. Cuatro Cienegas Basin (CCB has extremely low P levels and its endemic Bacillus are closely related to oligotrophic marine Firmicutes. Thus, we expected the pst operon of CCB to share the same evolutionary history and protein similarity to marine Firmicutes. Orthologs of the pst operon were searched in 55 genomes of Firmicutes and 13 outgroups. Phylogenetic reconstructions were performed for the pst operon and 14 concatenated housekeeping genes using maximum likelihood methods. Conserved domains and 3D structures of the phosphate-binding protein (PstS were also analyzed. The pst operon of Firmicutes shows two highly divergent clades with no correlation to the type of habitat nor a phylogenetic congruence, suggesting horizontal gene transfer. Despite sequence divergence, the PstS protein had a similar 3D structure, which could be due to parallel evolution after horizontal gene transfer events.

  6. Investigating reasons for the growth and survival of the dinoflagellate genus Neoceratium in oligotrophic subtropical gyres

    OpenAIRE

    Aldridge, David

    2014-01-01

    The dinoflagellate Neoceratium is frequently observed in oligotrophic subtropical gyres (OSGs) where major inorganic nutrients such as nitrogen and phosphorus are depleted in the surface waters. In Chapter 2, continuous plankton recorder (CPR) data demonstrate that Neoceratium inhabit surface waters of the North Atlantic subtropical gyre (NAG) throughout the year. The presence of Neoceratium in surface waters contrasts with the fact that nutrients are severely depleted in the surface 100 to 1...

  7. Distribution and host diversity of Amoebophryidae parasites across oligotrophic waters of the Mediterranean Sea

    Directory of Open Access Journals (Sweden)

    L. Guillou

    2010-10-01

    Full Text Available Sequences affiliated to Syndiniales (Marine alveolate, MALV regularly dominate 18S rDNA genetic libraries of nearly all marine ecosystems investigated so far. Among them, Amoebophryidae (MALV group II is composed of numerous and genetically distant environmental sequences, where Amoebophrya is the only known and formally described genus. Amoebophrya species include virulent pathogens for a wide range of dinoflagellate species. Beside their regular occurrence in marine ecosystems, their quantitative distribution and the environmental factors triggering host infection have barely been studied in open oligotrophic waters. In order to understand the functional role of these parasites in natural environments, we studied the distribution and contribution to the eukaryotic community of the small free-living stage of Amoebophryidae (the dinospores along a transect in the Mediterranean Sea, as well as their host diversity at three oligotrophic stations. Dinospores were more abundant at a coastal station (max. 1.5 × 103 cells ml−1 than in oligotrophic waters (max. 51 ± 16.3 cells ml−1, where they represented 10.3 to 34.9% of the total eukaryotic community at 40 and 30 m depth, respectively and 21.2% on average along the water column. Positive correlation was found between dinospore occurrence and higher concentration of NO3 + NO2 at the coastal station. At selected stations, out of 38 different dinoflagellates taxa identified, 15 were infected, among which a majority were not recognized as Amoebophryidae host so far. Prevalences (percentage of infected cells generally varied between 2% and 10%, with a notable exception for Blepharocysta paulsenii for which 25% of cells were infected at the station C. The present study shows that dinospores are able to thrive, infects and most probably exert a control on host populations both in coastal and ultra-oligotrophic open waters. Our results emphasize the role of parasitism in microbial food web dynamics and

  8. Phylogenetic Characterization of Methanogenic Assemblages in Eutrophic and Oligotrophic Areas of the Florida Everglades†

    OpenAIRE

    Castro, Hector; Ogram, Andrew; Reddy, K. R.

    2004-01-01

    Agricultural activities have produced well-documented changes in the Florida Everglades, including establishment of a gradient in phosphorus concentrations in Water Conservation Area 2A (WCA-2A) of the northern Everglades. An effect of increased phosphorus concentrations is increased methanogenesis in the eutrophic regions compared to the oligotrophic regions of WCA-2A. The goal of this study was to identify relationships between eutrophication and composition and activity of methanogenic ass...

  9. The fate of fixed nitrogen in oligotrophic marine sediments: an in situ study

    OpenAIRE

    Bonaglia, Stefano; Hylén, Astrid; Rattray, Jayne E.; Kononets, Mikhail Y.; Ekeroth, Nils; Roos, Per; Thamdrup, Bo; Brüchert, Volker; Hall, Per O. J.

    2016-01-01

    Given the increasing impacts of human activities on global nitrogen (N) cycle, investigations on N transformation processes in the marine environment have drastically increased in the last years. Benthic N cycling has mainly been studied in anthropogenically impacted estuaries and coasts, while its understanding in oligotrophic systems is still scarce. Here we report on rates of denitrification, anammox and dissimilatory nitrate reduction to ammonium (DNRA) studied by in situ incubations with...

  10. Nitrogen cycling in the deep sedimentary biosphere: nitrate isotopes in porewaters underlying the oligotrophic North Atlantic

    OpenAIRE

    S. D. Wankel; Buchwald, C.; W. Ziebis; C. B. Wenk; M. F. Lehmann

    2015-01-01

    Nitrogen (N) is a key component of fundamental biomolecules. Hence, its cycling and availability are central factors governing the extent of ecosystems across the Earth. In the organic-lean sediment porewaters underlying the oligotrophic ocean, where low levels of microbial activity persist despite limited organic matter delivery from overlying water, the extent and modes of nitrogen transformations have not been widely investigated. Here we use the N and oxygen (O) isotopic co...

  11. Seasonal and vertical distribution of putative ammonia-oxidizing thaumarchaeotal communities in an oligotrophic lake

    OpenAIRE

    Vissers, E.W.; Blaga, C. I.; Bodelier, P.L.E.; Muyzer, G; Schleper, C.; Sinninghe Damsté, J.S.; Tourna, M.; Laanbroek, H. J.

    2013-01-01

    The discovery of Archaea carrying an amoA gene coding for the A-subunit of ammonia monooxygenase gave a boost to studies aimed at detecting this gene under diverse conditions. Despite numerous studies describing the archaeal amoA gene abundance and richness in different habitats, the understanding of the freshwater ecology of potentially archaeal ammonia oxidizers, recently positioned in the phylum Thaumarchaeota, is still lacking. In a seasonal and vertical study of deep oligotrophic Lake Lu...

  12. Enhanced Particulate Organic Carbon Export at Eddy Edges in the Oligotrophic Western North Pacific Ocean.

    Directory of Open Access Journals (Sweden)

    Yung-Yen Shih

    Full Text Available Mesoscale eddies in the subtropical oligotrophic ocean are ubiquitous and play an important role in nutrient supply and oceanic primary production. However, it is still unclear whether these mesoscale eddies can efficiently transfer CO2 from the atmosphere to deep waters via biological pump because of the sampling difficulty due to their transient nature. In 2007, particulate organic carbon (POC fluxes, measured below the euphotic zone at the edge of warm eddy were 136-194 mg-C m-2 d-1 which was greatly elevated over that (POC flux = 26-35 mg-C m-2 d-1 determined in the nutrient-depleted oligotrophic waters in the Western North Pacific (WNP. In 2010, higher POC fluxes (83-115 mg-C m-2 d-1 were also observed at the boundary of mesoscale eddies in the WNP. The enhanced POC flux at the edge of eddies was mainly attributed to both large denuded diatom frustules and zooplankton fecal pellets based on scanning electron microscopy (SEM examination. The result suggests that mesoscale eddies in the oligotrophic waters in the subtropical WNP can efficiently increase the oceanic carbon export flux and the eddy edge is a crucial conduit in carbon sequestration to deep waters.

  13. Effect of arsenate As (V) on the biomarkers of Myriophyllum alterniflorum in oligotrophic and eutrophic conditions.

    Science.gov (United States)

    Krayem, M; Deluchat, V; Rabiet, M; Cleries, K; Lenain, J F; Saad, Z; Kazpard, V; Labrousse, P

    2016-03-01

    Alternate watermilfoil, Myriophyllum alterniflorum is an aquatic macrophyte found in the Limousin rivers (France) whose potential for biomonitoring of metal pollution has been demonstrated. The objective of the present study carried out in vitro was to identify biomarkers for an early detection of the pollution by a metalloid As (V) in eutrophic and oligotrophic conditions. A synthetic medium of similar composition to the waters of the River Vienne was prepared. The morphological development of watermilfoil was monitored for 30 days, with or without contamination by 100 μg L(-1) As (V). In addition, the mineralization of plants and the analysis of biomarkers (chlorophylls, photosynthetic and respiratory intensities …) were investigated after 21 days. Our results indicated that eutrophic medium, induced a decrease in chlorophyll pigments, in growth and an increase in H2O2 compared to the oligotrophic medium. While, the presence of As (V), led to a decrease in the osmotic potential, pigment content, photosynthesis and respiration rates and an inhibition of shoot branching of plants in both conditions. However, a significant increase in H2O2 content was noted in the eutrophic medium. Finally, As (V) was found to be more accumulated in roots than shoots in both conditions but was more accumulated in oligotrophic one. Therefore, we can conclude that the water trophic level modifies the response of M. alterniflorum in presence of arsenate. Thus, M. alterniflorum shows a great promise in water-quality biomonitoring. PMID:26766024

  14. Effect of arsenate As (V) on the biomarkers of Myriophyllum alterniflorum in oligotrophic and eutrophic conditions.

    Science.gov (United States)

    Krayem, M; Deluchat, V; Rabiet, M; Cleries, K; Lenain, J F; Saad, Z; Kazpard, V; Labrousse, P

    2016-03-01

    Alternate watermilfoil, Myriophyllum alterniflorum is an aquatic macrophyte found in the Limousin rivers (France) whose potential for biomonitoring of metal pollution has been demonstrated. The objective of the present study carried out in vitro was to identify biomarkers for an early detection of the pollution by a metalloid As (V) in eutrophic and oligotrophic conditions. A synthetic medium of similar composition to the waters of the River Vienne was prepared. The morphological development of watermilfoil was monitored for 30 days, with or without contamination by 100 μg L(-1) As (V). In addition, the mineralization of plants and the analysis of biomarkers (chlorophylls, photosynthetic and respiratory intensities …) were investigated after 21 days. Our results indicated that eutrophic medium, induced a decrease in chlorophyll pigments, in growth and an increase in H2O2 compared to the oligotrophic medium. While, the presence of As (V), led to a decrease in the osmotic potential, pigment content, photosynthesis and respiration rates and an inhibition of shoot branching of plants in both conditions. However, a significant increase in H2O2 content was noted in the eutrophic medium. Finally, As (V) was found to be more accumulated in roots than shoots in both conditions but was more accumulated in oligotrophic one. Therefore, we can conclude that the water trophic level modifies the response of M. alterniflorum in presence of arsenate. Thus, M. alterniflorum shows a great promise in water-quality biomonitoring.

  15. Ácidos fenólicos como antioxidantes

    Directory of Open Access Journals (Sweden)

    SOARES Sergio Eduardo

    2002-01-01

    Full Text Available Os compostos fenólicos têm sido muito estudados devido a sua influência na qualidade dos alimentos. Englobam uma gama enorme de substâncias, entre elas os ácidos fenólicos, os quais, por sua constituição química, possuem propriedades antioxidantes. Assim, a presente revisão procura reunir diversos estudos que avaliaram o potencial antioxidante dos ácidos fenólicos na conservação de alimentos lipídicos. Além disso, são reunidos também estudos sobre a ação antioxidante destes compostos no sistema biológico através da neutralização dos radicais livres gerados no organismo, que estão associados a diversas doenças como câncer e doenças cardiovasculares.

  16. El fenómeno de bullying en Colombia

    Directory of Open Access Journals (Sweden)

    Ángela Paola Contreras Álvarez

    2013-01-01

    Full Text Available El presente artículo describe el nefasto fenómeno de violencia y hostigamiento en ambientes escolares denominado bullying o matoneo escolar, el cual, aunque ha sido analizado desde finales de los años setenta en los países escandinavos, tuvo auge en Colombia en el año 2000, adquiriendo fuerza y permanencia con el uso de redes sociales, evidenciando la falta de políticas nacionales educativas para la atención e intervención del problema, al igual que el olvido de educación en derechos humanos y resolución pacífica de conflictos en los colegios. Esta problemática se desarrolla a través del significado del bullying, la descripción de sus antecedentes, descripción general del fenómeno, relación de los deberes del Estado frente al tema, la concepción del fenómeno desde la perspectiva de la Corte Constitucional, concluyendo en algunas sugerencias para abordar la problemática escolar.

  17. Distribution and host diversity of Amoebophryidae parasites across oligotrophic waters of the Mediterranean Sea

    Directory of Open Access Journals (Sweden)

    R. Siano

    2011-02-01

    Full Text Available Sequences affiliated to Syndiniales (Marine alveolate, MALV regularly dominate 18S rDNA genetic libraries of nearly all marine ecosystems investigated so far. Among them, Amoebophryidae (MALV group II is composed of numerous and genetically distant environmental sequences, where Amoebophrya is the only known and formally described genus. Amoebophrya species include virulent pathogens for a wide range of dinoflagellate species. Beside their regular occurrence in marine ecosystems, their quantitative distribution and the environmental factors triggering host infection have barely been studied in open oligotrophic waters. In order to understand the functional role of these parasites in natural environments, we studied the distribution and contribution to the eukaryotic community of the small free-living stage of Amoebophryidae (the dinospores along a transect in the Mediterranean Sea, as well as their host diversity at three oligotrophic stations. Dinospores were more abundant at a coastal station (max. 1.5 × 103 cells ml−1 than in oligotrophic waters (max. 51 ± 16.3 cells ml−1, where they represented 10.3 to 34.9% of the total eukaryotic community at 40 and 30 m depth, respectively and 21.2% on average along the water column. Positive correlation was found between dinospore occurrence and higher concentration of NO3 + NO2 at the coastal station. At selected stations, out of 38 different dinoflagellates taxa identified, 15 were infected, among which a majority were not recognized as Amoebophryidae host so far. Prevalences (percentage of infected cells generally varied between 1% and 10%, with a notable exception for Blepharocysta paulsenii for which 25% of cells were infected at the most oligotrophic station. The present study shows that dinospores are able to thrive and infect dinoflagellates both in coastal and ultra-oligotrophic open waters. Our results emphasize

  18. Understanding the Groundwater Hydrology of a Geographically-Isolated Prairie Fen: Implications for Conservation.

    Directory of Open Access Journals (Sweden)

    Prasanna Venkatesh Sampath

    Full Text Available The sources of water and corresponding delivery mechanisms to groundwater-fed fens are not well understood due to the multi-scale geo-morphologic variability of the glacial landscape in which they occur. This lack of understanding limits the ability to effectively conserve these systems and the ecosystem services they provide, including biodiversity and water provisioning. While fens tend to occur in clusters around regional groundwater mounds, Ives Road Fen in southern Michigan is an example of a geographically-isolated fen. In this paper, we apply a multi-scale groundwater modeling approach to understand the groundwater sources for Ives Road fen. We apply Transition Probability geo-statistics on more than 3000 well logs from a state-wide water well database to characterize the complex geology using conditional simulations. We subsequently implement a 3-dimensional reverse particle tracking to delineate groundwater contribution areas to the fen. The fen receives water from multiple sources: local recharge, regional recharge from an extensive till plain, a regional groundwater mound, and a nearby pond. The regional sources deliver water through a tortuous, 3-dimensional "pipeline" consisting of a confined aquifer lying beneath an extensive clay layer. Water in this pipeline reaches the fen by upwelling through openings in the clay layer. The pipeline connects the geographically-isolated fen to the same regional mound that provides water to other fen clusters in southern Michigan. The major implication of these findings is that fen conservation efforts must be expanded from focusing on individual fens and their immediate surroundings, to studying the much larger and inter-connected hydrologic network that sustains multiple fens.

  19. Understanding the Groundwater Hydrology of a Geographically-Isolated Prairie Fen: Implications for Conservation.

    Science.gov (United States)

    Sampath, Prasanna Venkatesh; Liao, Hua-Sheng; Curtis, Zachary Kristopher; Doran, Patrick J; Herbert, Matthew E; May, Christopher A; Li, Shu-Guang

    2015-01-01

    The sources of water and corresponding delivery mechanisms to groundwater-fed fens are not well understood due to the multi-scale geo-morphologic variability of the glacial landscape in which they occur. This lack of understanding limits the ability to effectively conserve these systems and the ecosystem services they provide, including biodiversity and water provisioning. While fens tend to occur in clusters around regional groundwater mounds, Ives Road Fen in southern Michigan is an example of a geographically-isolated fen. In this paper, we apply a multi-scale groundwater modeling approach to understand the groundwater sources for Ives Road fen. We apply Transition Probability geo-statistics on more than 3000 well logs from a state-wide water well database to characterize the complex geology using conditional simulations. We subsequently implement a 3-dimensional reverse particle tracking to delineate groundwater contribution areas to the fen. The fen receives water from multiple sources: local recharge, regional recharge from an extensive till plain, a regional groundwater mound, and a nearby pond. The regional sources deliver water through a tortuous, 3-dimensional "pipeline" consisting of a confined aquifer lying beneath an extensive clay layer. Water in this pipeline reaches the fen by upwelling through openings in the clay layer. The pipeline connects the geographically-isolated fen to the same regional mound that provides water to other fen clusters in southern Michigan. The major implication of these findings is that fen conservation efforts must be expanded from focusing on individual fens and their immediate surroundings, to studying the much larger and inter-connected hydrologic network that sustains multiple fens. PMID:26452279

  20. Fenómenos de transporte : un curso introductorio

    OpenAIRE

    Betancourt Grajales, Ramiro

    1991-01-01

    Fenómenos de transporte, es el nombre colectivo que se da al estudio sistemático e integrado de tres áreas clásicas de la ciencia de la Ingeniería : 1) Transporte de Energía o Calor, 2) Transporte de Masa o Difusión, y 3) Transporte de Cantidad de Movimiento o Impulso (Momentum en Inglés), o Dinámica de Fluidos. Debido a que con frecuencia el transporte de masa y de calor ocurren en un fluido, algunos planes de estudio incluyen estos procesos en su tratamiento de la mecánica de fluidos....

  1. Fenótipos clínicos de asma grave Clinical phenotypes of severe asthma

    Directory of Open Access Journals (Sweden)

    Roseliane de Souza Araújo Alves

    2008-09-01

    Full Text Available OBJETIVO: Estabelecer os fenótipos clínicos em portadores de asma grave. MÉTODOS: Foram estudados, retrospectivamente, 111 pacientes em um ambulatório especializado. Os pacientes foram avaliados e acompanhados de maneira sistemática, estabelecendo-se ao final do acompanhamento a adesão e o controle ou não da doença por dados clínicos e funcionais. A resistência ao tratamento foi definida como o não preenchimento, ao final do acompanhamento, por pelo menos seis meses, dos critérios de controle de asma, apesar do uso correto e adesão à medicação. Os fenótipos foram determinados por análise fatorial e comparados por testes diversos. RESULTADOS: Ao final, 88 pacientes foram considerados aderentes e 23 não aderentes. Por análise fatorial do grupo aderente, quatro fenótipos foram determinados: o fenótipo 1 (28 pacientes, formado pelos pacientes resistentes ao tratamento, com maior freqüência de sintomas noturnos, maior número de exacerbações e uso mais freqüente de broncodilatador de resgate; o fenótipo 2 (48 pacientes, formado pelos pacientes com obstrução persistente, com menores valores de relação volume expiratório forçado no primeiro segundo/capacidade vital forçada na avaliação inicial, idade mais avançada e maior tempo de doença; o fenótipo 3 (42 pacientes, representa os pacientes com rinossinusite alérgica, sendo constituído de não fumantes com obstrução predominantemente reversível; e o fenótipo 4 (15 pacientes, formado por casos com história de intolerância à aspirina associado à asma quase fatal. CONCLUSÕES: Um número significativo de portadores de ama grave não adere ao tratamento. Muitos pacientes com asma grave têm obstrução irreversível, mas o fenótipo clínico mais relevante é constituído pelos pacientes resistentes ao tratamento habitual.OBJECTIVE: To characterize clinical phenotypes of severe asthma. METHODS: A total of 111 patients were retrospectively evaluated at a

  2. A novel cohabitation between two diazotrophic cyanobacteria in the oligotrophic ocean.

    Science.gov (United States)

    Momper, Lily M; Reese, Brandi Kiel; Carvalho, Gustavo; Lee, Patrick; Webb, Eric A

    2015-04-01

    The cyanobacterial genus Trichodesmium is biogeochemically significant because of its dual role in nitrogen and carbon fixation in the oligotrophic ocean. Trichodesmium species form colonies that can be easily enriched from the water column and used for shipboard rate measurements to estimate their contribution to oceanic carbon and nitrogen budgets. During a July 2010 cruise near the Hawaiian Islands in the oligotrophic North Pacific Subtropical Gyre, a specific morphology of Trichodesmium puff-form colonies were examined under epifluorescent microscopy and found to harbor a colonial endobiont, morphologically identified as the heterocystous diazotrophic cyanobacterium Calothrix. Using unialgal enrichments obtained from this cruise, we show that these Calothrix-like heterocystous cyanobionts (hetDA for 'Trichodesmium-associated heterocystous diazotroph') fix nitrogen on a diurnal cycle (maximally in the middle of the light cycle with a detectable minimum in the dark). Gene sequencing of nifH from the enrichments revealed that this genus was likely not quantified using currently described quantitative PCR (qPCR) primers. Guided by the sequence from the isolate, new hetDA-specific primers were designed and subsequent qPCR of environmental samples detected this diazotroph from surface water to a depth of 150 m, reaching densities up to ∼ 9 × 10(3) l(-1). Based on phylogenetic relatedness of nifH and 16S rRNA gene sequences, it is predicted that the distribution of this cyanobiont is not limited to subtropical North Pacific but likely reaches to the South Pacific and Atlantic Oceans. Therefore, this previously unrecognized cohabitation, if it reaches beyond the oligotrophic North Pacific, could potentially influence Trichodesmium-derived nitrogen fixation budgets in the world ocean.

  3. Dust deposition in an oligotrophic marine environment: impact on the carbon budget

    Directory of Open Access Journals (Sweden)

    C. Guieu

    2014-01-01

    Full Text Available By bringing new nutrients and particles to the surface ocean, atmospheric deposition impacts biogeochemical cycles. The extent to which those changes are modifying the carbon balance in oligotrophic environments such as the Mediterranean Sea that receives important Saharan dust fluxes is unknown. DUNE project provides the first attempt to evaluate the changes induced in the carbon budget of an oligotrophic system after simulated Saharan dust wet and dry deposition events. Here we report the results for the 3 distinct artificial dust seeding experiments in large mesocosms that were conducted in the oligotrophic waters of the Mediterranean Sea in summer 2008 and 2010. Simultaneous measurements of the metabolic rates (C fixation, C respiration in the water column have shown that the dust deposition did not change drastically the metabolic balance as the tested waters remained net heterotroph (i.e. net primary production to bacteria respiration ratio < 1 and in some cases the net heterotrophy was even enhanced by the dust deposition. Considering the different terms of the carbon budget, we estimate that it was balanced with a dissolved organic carbon (DOC consumption of at least 10% of the initial stock. This corresponds to a fraction of the DOC stock of the surface mixed layer that consequently will not be exported during the winter mixing. Although heterotrophic bacteria were found to be the key players in the response to dust deposition, net primary production increased about twice in case of simulated wet deposition (that includes anthropogenic nitrogen and a small fraction of particulate organic carbon was still exported. Our estimated carbon budgets are an important step forward in the way we understand dust deposition and associated impacts on the oceanic cycles. They are providing knowledge about the key processes (i.e. bacteria respiration, aggregation that need to be considered for an integration of atmospheric deposition in marine

  4. Blastodinium spp. infect copepods in the ultra-oligotrophic marine waters of the Mediterranean Sea

    Directory of Open Access Journals (Sweden)

    A. Skovgaard

    2011-03-01

    Full Text Available Blastodinium are chloroplast-containing dinoflagellates which infect a wide range of copepods. They develop inside the gut of their host, where they produce successive generations of sporocytes that are eventually expelled through the anus of the copepod. Here, we report on copepod infections in the oligotrophic to ultra-oligotrophic waters of the Mediterranean Sea sampled during the BOUM cruise. Based on a DNA-stain screening of gut contents, 16% of copepods were possibly infected in samples from the Eastern Mediterranean, with up to 51% of Corycaeidae, 33% of Calanoida, but less than 2% of Oithonidae and Oncaeidae. Parasites were classified into distinct morphotypes, with some tentatively assigned to species B. mangini, B. contortum, and B. cf. spinulosum. Based upon the SSU rDNA gene sequence analyses of 15 individuals, the genus Blastodinium was found to be polyphyletic, containing at least three independent clusters. The first cluster grouped all sequences retrieved from parasites of Corycaeidae and Oncaeidae during this study, and included sequences of Blastodinium mangini (the "mangini" cluster. Sequences from cells infecting Calanoida belonged to two different clusters, one including B. contortum (the "contortum" cluster, and the other uniting all B. spinulosum-like morphotypes (the "spinulosum" cluster. Cluster-specific oligonucleotidic probes were designed and tested by FISH in order to assess the distribution of dinospores, the Blastodinium dispersal and infecting stage. Probe-positive cells were all small thecate dinoflagellates, with lengths ranging from 7 to 18 μm. Maximal abundances of Blastodinium dinospores were detected at the Deep Chlorophyll Maximum (DCM or slightly below. This was in contrast to distributions of autotrophic pico- and nanoplankton, microplanktonic dinoflagellates, and nauplii which showed maximal concentrations above the DCM. The distinct distributions of dinospores and nauplii argues against infection

  5. A preliminary carbon budget for two oligotrophic hardwater lakes in the Forsmark area, Sweden

    Energy Technology Data Exchange (ETDEWEB)

    Nilsson, Eva [Uppsala Univ. (Sweden). Dept. of Limnology

    2001-06-01

    The Swedish Nuclear Fuel and Waste Management Co (SKB) is responsible for management and disposal of Swedish radioactive waste. The company is planning to construct repositories that will keep radioactive waste away from humans for hundreds of thousands of years. In a safety assessment of the repositories hypothetical releases are used to evaluate the robustness of the repositories. It is important to know how the radioactive nuclides would react if they were released and by which way they could enter the living biota. SFR are responsible for the disposal of low radioactive waste and close to the nuclear plant in Forsmark there is a storage for low radioactive waste. At the moment this storage is located in the bedrock far below the sea level but due to land-rise in the area it will in the future be located above sea level. Hence, it is of importance to know how the surface ecosystems in the area are functioning. A carbon budget for the aquatic ecosystem above SFR in Oeresundsgrepen exist, but it is also important to have a carbon budget for the surface systems in the Forsmark area since SFR in the future will be situated above sea level. Carbon budgets can be used to get a picture of how an ecosystem functions. The carbon flow shows how carbon is transported through a food web from lower trophic levels, e.g. plants and bacteria to higher trophic levels such as fish. Oligotrophic hardwater lakes are the most important lakes in the Forsmark area. This report aims to give a picture of a potential flow of carbon through the ecosystem in two oligotrophic hard-water lakes, Lake Haellefjaerd and Lake Eckarfjaerden. Macrophyte, mainly Chara, were calculated to make up the largest part of the biomass and production in both lakes. Benthic bacteria and microphytobenthos (benthic photosynthesising microorganisms) were other large contributors to the production. Benthic bacteria were found responsible for a major part of respiration and, hence, consumption of carbon in the

  6. Diversity of picoeukaryotes at an oligotrophic site off the Northeastern Red Sea Coast.

    KAUST Repository

    Acosta, Francisco

    2013-08-20

    Picoeukaryotes are protists ≤ 3 μm composed of a wide diversity of taxonomic groups. They are an important constituent of the ocean\\'s microbiota and perform essential ecological roles in marine nutrient and carbon cycles. Despite their importance, the true extent of their diversity has only recently been uncovered by molecular surveys that resulted in the discovery of a substantial number of previously unknown groups. No study on picoeukaryote diversity has been conducted so far in the main Red Sea basin-a unique marine environment characterized by oligotrophic conditions, high levels of irradiance, high salinity and increased water temperature.

  7. Landform design for a fen wetland on a tailings sand deposit in northern Alberta

    Energy Technology Data Exchange (ETDEWEB)

    McKenna, G.T.; Papini, A.G.; Scordo, E.B. [BGC Engineering Inc., Vancouver, BC (Canada); Wytrykush, C. [Syncrude Canada Ltd., Edmonton, AB (Canada)

    2010-07-01

    This paper discussed one of the first fens to be established in a post-mining area of the Athabasca oil sands region. The entire watershed is specifically designed to support a wetland, and it will be constructed on a soft tailings deposit. A fen is a peat-accumulating wetland with a water table that is at, or close to, the surface consisting of mineral-saturated water coming from either groundwater or surface water. In order to monitor and adjust the fen design for field conditions, a full hydrological site investigation was launched together with parallel research programs involving the creation of a conservative landform design with controls over surface water and groundwater seepage inputs. Controlling the salinity of fen waters from tailings consolidation and seepage over time is a critical component to fen design. There are a limited number of documented examples of large-scale constructed fen wetlands.

  8. Understanding toxicity at the watershed scale : design of the Syncrude Sandhill Fen watershed research project

    International Nuclear Information System (INIS)

    Fens are peat-accumulating wetlands with a water table consisting of mineral-rich ground or surface water. This study discussed the construction of a fen-type reclaimed wetland constructed in a post-mining oil sands landscape. Syncrude Canada's Sandhill fen watershed project represents the first attempt at constructing a fen wetland in the oil sands region. The wetland and its watershed will be constructed on a soft tailings deposit. The design basis for the fen and watershed was developed by a team of researchers and scientists. The aim of the fen design was to control the salinity caused by tailings consolidation and seepage over time. Methods of mitigating potentially toxic effects from salinity were discussed.

  9. Fenómeno de Koebner The Koebner phenomenon

    Directory of Open Access Journals (Sweden)

    R E Achenbach

    2011-09-01

    Full Text Available Descrito en 1871 por Heinrich Koebner, su fenómeno es uno de los más conocidos en la Dermatología. Koebner lo describe en un paciente con psoriasis que sufrió escoriaciones múltiples y una mordedura de caballo. Su figura fue una de las más destacadas en la Dermatología del siglo 19. Se revisa la lista de entidades con fenómeno Koebner y sus variantes, los tipos de injurias y su patogenia.First described in 1871, the Koebner phenomenon is one of the most well-known entities in dermatology. Heinrich Koebner is credited with the first adequate description of this peculiar disposition of psoriatic skin. He was one of the outstanding dermatologists of the 19th Century and reported the formation of psoriasiform lesions in uninvolved skin after excoriations and horse bites. Types of Koebner response, a list of injuries capable to produce it and a review of the pathogenesis are reviewed.

  10. Understanding the Groundwater Hydrology of a Geographically-Isolated Prairie Fen: Implications for Conservation

    OpenAIRE

    Sampath, Prasanna Venkatesh; Liao, Hua-Sheng; Curtis, Zachary Kristopher; Patrick J Doran; Matthew E Herbert; May, Christopher A.; Li, Shu-Guang

    2015-01-01

    The sources of water and corresponding delivery mechanisms to groundwater-fed fens are not well understood due to the multi-scale geo-morphologic variability of the glacial landscape in which they occur. This lack of understanding limits the ability to effectively conserve these systems and the ecosystem services they provide, including biodiversity and water provisioning. While fens tend to occur in clusters around regional groundwater mounds, Ives Road Fen in southern Michigan is an example...

  11. Impact of grazing on vegetation and on selected plant species of calcareous fens

    OpenAIRE

    Stammel, Barbara

    2005-01-01

    Calcareous fens are traditionally mown in autumn, which maintains species rich vegetation types (Caricion davallianae, Molinion caeruleae). Nowadays, abandonment due to changes in agriculture causes a decline of many characteristic plant species of fen meadows due to litter accumulation and dominance of few competitive species. The aim of this study is to evaluate grazing as an alternative management tool to mowing. The impact of grazing and mowing on the vegetation of calcareous fens in the ...

  12. Post-fire regeneration of vegetation on sandy oligotrophic soil, in Itabaiana, Sergipe, Brazil

    Directory of Open Access Journals (Sweden)

    Túlio Vinicius Paes Dantas

    2015-07-01

    Full Text Available Two models of post-disturbance regeneration of vegetation in areas of oligotrophic soils have been proposed for temperate regions. The first model is characterized by rapid recovery of the floristic composition, due to the fire resistance of plants; while in the second model, the fire causes extensive mortality and the recovery occurs by recruitment from the seed bank. Since these models have been rarely tested in tropical oligotrophic environments, we applied them in the analysis of floristic compositions in three areas with different post-fire regeneration times in Sergipe State, Brazil. The regeneration followed the seed bank recruitment model in places of bare ground, with a progressive increase in plant density and changes in the relative abundance and dominance of the populations along the successional process. The parameters that best allowed the succession evaluation were the floral similarity, plant height and density, which increased as regeneration progressed. The stem diameter and tillering were inconclusive as parameters for assessing the regeneration progress.

  13. Phytoplankton biovolume is independent from the slope of the size spectrum in the oligotrophic atlantic ocean

    KAUST Repository

    Moreno-Ostos, Enrique

    2015-08-06

    Modelling the size-abundance spectrum of phytoplankton has proven to be a very useful tool for the analysis of physical-biological coupling and the vertical flux of carbon in oceanic ecosystems at different scales. A frequent observation relates high phytoplankton biovolume in productive regions with flatter spectrum slope and the opposite in oligotrophic ecosystems. Rather than this, the relationship between high biovolume phytoplankton assemblages and flatter size-abundance spectra does not correspond with measurements of the phytoplankton community in the Atlantic Ocean open waters. As part of the Malaspina Circunnavegation Expedition, sixty seven sampling stations within the Atlantic Ocean covering six oceanographic provinces, at different seasons, produced a complete set of phytoplankton size-spectra whose slope and biovolume did not show any obvious interrelation. In these oligotrophic sites, small (procaryotes) and medium-size (nanoplankton) cells are responsible for the most part of biovolume, and their response to environmental conditions does not apply to changes in the size-abundance spectrum slope as expected in richer, large-cell dominated ecosystems.

  14. Water flow and solute transport in floating fen root mats

    Science.gov (United States)

    Stofberg, Sija F.; EATM van der Zee, Sjoerd

    2015-04-01

    Floating fens are valuable wetlands, found in North-Western Europe, that are formed by floating root mats when old turf ponds are colonized by plants. These terrestrialization ecosystems are known for their biodiversity and the presence of rare plant species, and the root mats reveal different vegetation zones at a small scale. The vegetation zones are a result of strong gradients in abiotic conditions, including groundwater dynamics, nutrients and pH. To prevent irreversible drought effects such as land subsidence and mineralization of peat, water management involves import of water from elsewhere to maintain constant surface water levels. Imported water may have elevated levels of salinity during dry summers, and salt exposure may threaten the vegetation. To assess the risk of exposure of the rare plant species to salinity, the hydrology of such root mats must be understood. Physical properties of root mats have scarcely been investigated. We have measured soil characteristics, hydraulic conductivity, vertical root mat movement and groundwater dynamics in a floating root mat in the nature reserve Nieuwkoopse Plassen, in the Netherlands. The root mat mostly consists of roots and organic material, in which the soil has a high saturated water content, and strongly varies in its stage of decomposition. We have found a distinct negative correlation between degree of decomposition and hydraulic conductivity, similar to observations for bogs in the literature. Our results show that the relatively young, thin edge of the root mat that colonizes the surface water has a high hydraulic conductivity and floats in the surface water, resulting in very small groundwater fluctuations within the root mat. The older part of the root mat, that is connected to the deeper peat layers is hydrologically more isolated and the material has a lower conductivity. Here, the groundwater fluctuates strongly with atmospheric forcing. The zones of hydraulic properties and vegetation, appear to

  15. Nuevos fenómenos en erupciones cometarias

    Science.gov (United States)

    Silva, A.

    Se discuten aquí tres procesos físicos novedosos encontrados en la actividad de cometas: 1) El rol de una distribución de granos de hielo como fuente extendida de H2O en la coma, 2) El efecto de una discontinuidad en el plasma cometario, llamada Cometopausa, sobre la excitación del radical OH , y 3) La actividad por erupciones a grandes distancias heliocéntricas (r > 5 AU). Con respecto a 1) y 2), se presentan modelos que ajustan bien con las observaciones. En cuanto a 3), se presentan explicaciones posibles al fenómeno, y se trata el interesante caso de Chirón 2060, basándose en observaciones propias tomadas desde el CASLEO y datos anteriores.

  16. Fenómenos de interfase en sistemas coloidales

    OpenAIRE

    Bregni, Carlos; Serrao, Rosa

    1988-01-01

    Uno de los aspectos más importantes en la formulación de dispersiones de aplicación farmacéutica, es el conocimiento de aquellas propiedades fisicoquímicas, que involucran fenómenos de superficie e interfase en sistemas de naturaleza coloidal. La medida de conductividad específica y de viscosidad aparente en función de la concentración de electrolitos presentes en el medio permitió determinar la concentración crítica en la que se logra la saturación de la superficie de la partícula coloidal d...

  17. Throughflow as a determining factor for habitat contiguity in a near-natural fen

    NARCIS (Netherlands)

    Loon, A.H. van; Schot, P.P.; Griffioen, J.; Bierkens, M.F.P.; Batelaan, O.; Wassen, M.J.

    2009-01-01

    Knowledge of the hydrological mechanisms that underlie stable plant communities within natural fens is essential for the improvement of current fen restoration and conservation strategies. In this study, steady-state groundwater modelling was performed to quantify the impact of throughflow mechanism

  18. Microbial activity and community structure in two drained fen soils in the Ljubljana Marsh

    NARCIS (Netherlands)

    Kraigher, Barbara; Stres, Blaz; Hacin, Janez; Ausec, Luka; Mahne, Ivan; van Elsas, Jan D.; Mandic-Mulec, Ines

    2006-01-01

    Fen peatlands are specific wetland ecosystems containing high soil organic carbon (SOC). There is a general lack of knowledge about the microbial communities that abound in these systems. We examined the microbial activity and community structure in two fen soils differing in SOC content sampled fro

  19. Nutrient imitations in an extant and drained poor fen : implications for restoration

    NARCIS (Netherlands)

    VanDuren, IC; Boeye, D; Grootjans, AP

    1997-01-01

    In a species-rich poor fen (Caricetum nigrae) and a species-poor drained fen, the difference in nutrient limitation of the vegetation was assessed in a full-factorial fertilization experiment with N, P and K. The results were compared to the nutrient ratios of plant material and to chemical analysis

  20. Comparison of nitrogen and phosphorus fluxes in some European fens and floodplains

    NARCIS (Netherlands)

    Wassen, M.J.; Olde Venterink, H.

    2006-01-01

    Question: How do nitrogen and phosphorus budgets and balances differ between eutrophic fens and floodplains in western Europe and fens and floodplains in Poland, where we expect less eutrophication to occur? Location: Wetlands along the rivers Dommel (The Netherlands), Zwarte Beek (Belgium) and Bieb

  1. Remotely sensed hydrological isolation : A key factor predicting plant species distribution in fens

    NARCIS (Netherlands)

    Sanders, M.E.

    1999-01-01

    In fens the species composition, vegetation structure and succession rate are determined by vegetation management and water chemistry, particularly by the base status and nutrient status. Base-rich and nutrient-rich surface water causes fens to become eutrophied, which leads to an increased biomass

  2. Effects of re-oligotrophication and climate warming on plankton richness and community stability in a deep mesotrophic lake

    NARCIS (Netherlands)

    Pomati, F.; Matthews, B.; Jokela, J.; Schildknecht, A.; Ibelings, B.W.

    2012-01-01

    We studied the effects of re-oligotrophication and climate warming on plankton richness and community stability over a period of 30 years in the deep mesotrophic Lake Zurich (Switzerland). We assembled monthly time-series of phytoplankton and zooplankton taxonomic richness, phytoplankton functional

  3. Faster growth of the major prokaryotic versus eukaryotic CO2 fixers in the oligotrophic ocean.

    Science.gov (United States)

    Zubkov, Mikhail V

    2014-01-01

    Because maintenance of non-scalable cellular components--membranes and chromosomes--requires an increasing fraction of energy as cell size decreases, miniaturization comes at a considerable energetic cost for a phytoplanktonic cell. Consequently, if eukaryotes can use their superior energetic resources to acquire nutrients with more or even similar efficiency compared with prokaryotes, larger unicellular eukaryotes should be able to achieve higher growth rates than smaller cyanobacteria. Here, to test this hypothesis, we directly compare the intrinsic growth rates of phototrophic prokaryotes and eukaryotes from the equatorial to temperate South Atlantic using an original flow cytometric (14)CO2-tracer approach. At the ocean basin scale, cyanobacteria double their biomass twice as frequently as the picoeukaryotes indicating that the prokaryotes are faster growing CO2 fixers, better adapted to phototrophic living in the oligotrophic open ocean-the most extensive biome on Earth.

  4. Laboratory experiment to determine phosphate release rates from sediments of a formerly oligotrophic lake (Silbersee, Cuxhaven)

    Science.gov (United States)

    Elmarami, Hatem; Greskowiak, Janek; Hamann, Enrico; Massmann, Gudrun

    2016-04-01

    The Silbersee is a small, formerly oligotrophic lake in northwestern Germany which still contains rare character species for oligotrophic lakes (Isoëtes lacustris, Littorella uniflora) threatened by eutrophication. It was suspected that the lake sediments and the redox conditions in the hypolimnon play an important role with regard to eutrophication, potentially releasing phosphorus (P) into the water column. This was the motivation to conduct experiments to estimate the release rate of phosphorus into the lake. It had been noted that the P concentrations in the bottom water were higher during summer in the stagnation phase, when conditions turned sulfidic. Eight sediment cores were taken with a Mondsee-corer (manufactured by UWITEC) at different sites of the lake. The thickness of the sediment within the cores ranged from 15cm to 35 cm and were overlying by approximately 40cm of lake water water. The headspace was approximately 10cm. The cores were stored in a fridge first under oxic, then under anoxic conditions as observed in the lake bottom water in the different seasons. Redox conditions were maintained by bubbling with oxygen and nitrogen gas during the respective time periods. During the experiment, the temperature was held constant to match the water temperature measured at the bottom of the lake (~ 7±1°C). Concentrations of total phosphorus (TP) and dissolved phosphorus (DP), iron (Fe) and dissolved oxygen (DO) as well as pH were measured under oxic and anoxic conditions in the water column. The results showed that TP, DP and Fe concentrations were higher under anoxic conditions than under oxic conditions. The observed increase of phosporous in the water column during the anoxic phase was presumably a result of (i) reductive Fe-oxides dissolution and the corresponding loss of sorption sites and (ii) desorption of phosphorous via surface complexation reactions due to pH changes during the experiment.

  5. Water level influences on body condition of Geophagus brasiliensis (Perciformes: Cichlidae in a Brazilian oligotrophic reservoir

    Directory of Open Access Journals (Sweden)

    Alejandra Filippo Gonzalez Neves dos Santos

    2004-09-01

    Full Text Available Effects of water level fluctuations on body condition of Geophagus brasiliensis were studied in a 30 km² Brazilian oligotrophic reservoir. Physiological condition (K and gonadosomatic index (GSI were compared according to water level (low and high. Females' best conditions were associated to higher resources availability during high water, since gonad development did not change between low and high water. Males' condition did not change between water levels, while the highest gonad development occurred in low water. Females presented higher reproductive investment than males, which allocated most of energy for somatic development. This strategy could be a mechanism to undergo the stress caused by oligotrophic characteristics of the reservoir enhanced during low water level.Efeitos do nível da água na condição de Geophagus brasiliensis foram analisados em um reservatório oligotrófico. A condição fisiológica (K e o índice gonadossomático (IGS foram comparados entre os níveis da água (baixo e alto. Melhores condições de fêmeas foram associadas a maiores disponibilidades de recursos no nível alto, já que o desenvolvimento gonadal não variou. Não foram registradas diferenças na condição de machos, contudo maiores valores de IGS ocorreram no nível baixo. Fêmeas apresentaram elevado investimento reprodutivo, enquanto machos investiram mais no desenvolvimento somático. Tal estratégia pode ser um mecanismo para suportar o estresse causado pelas características oligotróficas do reservatório, intensificadas durante o período de níveis baixos da água.

  6. A caveat regarding diatom-inferred nitrogen concentrations in oligotrophic lakes

    Science.gov (United States)

    Arnett, Heather A.; Saros, Jasmine E.; Mast, M. Alisa

    2012-01-01

    Atmospheric deposition of reactive nitrogen (Nr) has enriched oligotrophic lakes with nitrogen (N) in many regions of the world and elicited dramatic changes in diatom community structure. The lakewater concentrations of nitrate that cause these community changes remain unclear, raising interest in the development of diatom-based transfer functions to infer nitrate. We developed a diatom calibration set using surface sediment samples from 46 high-elevation lakes across the Rocky Mountains of the western US, a region spanning an N deposition gradient from very low to moderate levels (lakes, ordination analysis identified that nitrate, specific conductance, total phosphorus, and hypolimnetic water temperature were related to diatom distributions. A transfer function was developed for nitrate and applied to a sedimentary diatom profile from Heart Lake in the central Rockies. The model coefficient of determination (bootstrapping validation) of 0.61 suggested potential for diatom-inferred reconstructions of lakewater nitrate concentrations over time, but a comparison of observed versus diatom-inferred nitrate values revealed the poor performance of this model at low nitrate concentrations. Resource physiology experiments revealed that nitrogen requirements of two key taxa were opposite to nitrate optima defined in the transfer function. Our data set reveals two underlying ecological constraints that impede the development of nitrate transfer functions in oligotrophic lakes: (1) even in lakes with nitrate concentrations below quantification (lakes switch to P limitation after receiving only modest inputs of reactive N, shifting the controls on diatom species changes along the length of the nitrate gradient. These constraints suggest that quantitative inferences of nitrate from diatom assemblages will likely require experimental approaches.

  7. Comparisons of soil nitrogen mass balances for an ombrotrophic bog and a minerotrophic fen in northern Minnesota

    Science.gov (United States)

    We compared the N budgets of an ombrotrophic bog and a minerotrophic fen to quantify the importance of denitrification in peatlands and their watersheds. We also compared the watershed upland mineral soils to bog/fen peat; lagg and transition zone peat to central bog/fen peat; an...

  8. Computerbasiert prüfen [Computer-based Assessment

    Directory of Open Access Journals (Sweden)

    Frey, Peter

    2006-08-01

    Full Text Available [english] Computer-based testing in medical education offers new perspectives. Advantages are sequential or adaptive testing, integration of movies or sound, rapid feedback to candidates and management of web-based question banks. Computer-based testing can also be implemented in an OSCE examination. In e-learning environments formative self-assessment are often implemented and gives helpful feedbacks to learners. Disadvantages in high-stake exams are the high requirements as well for the quality of testing (e.g. standard setting as additionally for the information technology and especially for security. [german] Computerbasierte Prüfungen im Medizinstudium eröffnen neue Möglichkeiten. Vorteile solcher Prüfungen liegen im sequentiellen oder adaptiven Prüfen, in der Integration von Bewegtbildern oder Ton, der raschen Auswertung und zentraler Verwaltung der Prüfungsfragen via Internet. Ein Einsatzgebiet mit vertretbarem Aufwand sind Prüfungen mit mehreren Stationen wie beispielsweise die OSCE-Prüfung. Computerbasierte formative Selbsttests werden im Bereiche e-learning häufig angeboten. Das hilft den Lernenden ihren Wissensstand besser einzuschätzen oder sich mit den Leistungen anderer zu vergleichen. Grenzen zeigen sich bei den summativen Prüfungen beim Prüfungsort, da zuhause Betrug möglich ist. Höhere ärztliche Kompetenzen wie Untersuchungstechnik oder Kommunikation eigenen sich kaum für rechnergestützte Prüfungen.

  9. BOREAS TE-1 SSA-Fen Soil Profile Nutrient Data

    Science.gov (United States)

    Papagno, Andrea; Anderson, Darwin; Newcomer, Jeffrey A. (Editor); Hall, Forrest G. (Editor)

    2000-01-01

    The BOREAS TE-1 team collected various data to characterize the soil-plant systems in the BOREAS SSA. Particular emphasis was placed on nutrient biochemistry, the stores and transfers of organic carbon, and how the characteristics were related to measured methane fluxes. The overall traniect in the Prince Albert National Park (Saskatchewan, Canada) included the major plant communities and related soils that occurred in that section of the boreal forest. Soil physical, chemical, and biological measurements along the transect were used to characterize the static environment, which allowed them to be related to methane fluxes. Chamber techniques were used to provide a measure of methane production/uptake. Chamber measurements coupled with flask sampling were used to determine the seasonality of methane fluxes. This particular data set contains soil profile measurements of various nutrients at the SSA-Fen site. The data were collected from 23-May to 21-Oct- 1994. The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

  10. Facile fabrication of FeN nanoparticles/nitrogen-doped graphene core-shell hybrid and its use as a platform for NADH detection in human blood serum.

    Science.gov (United States)

    Balamurugan, Jayaraman; Thanh, Tran Duy; Kim, Nam Hoon; Lee, Joong Hee

    2016-09-15

    Herein, we present a novel strategy for the synthesis of an iron nitride nanoparticles-encapsulated nitrogen-doped graphene (FeN NPs/NG) core-shell hierarchical nanostructure to boost the electrochemical performance in a highly sensitive, selective, reproducible, and stable sensing platform for nicotinamide adenine dinucleotide (NADH). This core-shell hierarchical nanostructure provides an excellent conductive network for effective charge transfer and avoids the agglomeration and restacking of NG sheets, which provides better access to the electrode material for NADH oxidation. The FeN NPs/NG core-shell hierarchical nanostructure demonstrates direct and mediatorless responses to NADH oxidation at a low potential. This material displays a high sensitivity of 0.028μA/μMcm(2), a wide linear range from 0.4 to 718μM, and a detection limit of 25nM with a fast response time of less than 3s. The interferences from common interferents, such as glucose, uric acid, dopamine, and ascorbic acid, are negligible. The fabricated sensor was further tested for the determination of NADH in human blood serum. The resulting high sensitivity, excellent selectivity, outstanding stability, and good reproducibility make the proposed FeN NPs/NG core-shell hierarchical nanostructure as a promising candidate for biomedical applications. PMID:27104586

  11. Changes in Colorado Subalpine Fen Peat Stratigraphy and Humification During the Holocene

    Science.gov (United States)

    Sullivan, D. G.

    2013-12-01

    This project focuses on the record of peat stratigraphy and decomposition preserved in cores taken from minerotrophic peatlands in Colorado. Subalpine peatlands in the Colorado Rocky Mountains and in the Colorado Plateau cover only about 2% of the state's land area, yet these wetlands provide important wildlife habitat and ecosystem services. The peatlands in Colorado are fens, and, while summer precipitation contributes to the local hydrology, the fens are only found in locations where winter snowpack persists long enough into the summers to maintain sufficiently high water tables to preserve the peat. We hypothesized that changes in summer precipitation and winter snowpack through the Holocene would be evident in the degree of peat humification and stratigraphy. We were interested in determining how warmer summer conditions early in the Holocene influenced precipitation, particularly summer monsoons, and thus, groundwater. In addition, our research using lake sediment cores in the region indicates that sediment organic content may fluctuate with paleotemperature. We sought to determine whether fens likewise preserve evidence of relatively low magnitude temperature changes, including those associated with the Medieval Climate Anomaly (MCA) and the Little Ice Age (LIA). Since fens persist in the region only under marginal conditions, they are very sensitive to fluctuations in climate and consequent hydrological responses. Nine fens were sampled in the study. Fen stratigraphy was studied at all of the sites. Humification analysis and bulk density and organic content determinations were conducted at one-centimeter intervals on cores from four of the fens. Core chronology was established using radiocarbon dating. Our results suggest that warmer summers in the early Holocene led to earlier snowmelt at lower elevations. Fens located near the lower margins of the subalpine zone (<3100 m elevation) ceased to accumulate peat during this period, changing to alluvial

  12. Los compuestos fenólicos en la autodefensa de los vegetales

    Directory of Open Access Journals (Sweden)

    Maestro-Durán, R.

    1993-12-01

    Full Text Available This article covers the studies on phytoalexins activity of phenolic compounds (cinnamic acids, flavonoids, isoflavonoids, deoxianthocyanins, stilbenes, coumarins, chromones against fungi and bacteria. The relationship between hydrophilic-lipophilic balance activity is reported. Finally some reports on the preparation of synthetic phytoalexins sharing structural similarities with the natural ones (stilbenes, epi-catechin derivatives, of commercial interest as pesticides, insecticides and fungicides, are revised.

    En este trabajo se recogen los estudios sobre la actividad como fitoalexinas (compuestos post-infeccionales cuya formación implica o desrrepresión de genes o activación de un sistema enzimático que no operaba antes de la infección, tanto frente a hongos como frente a bacterias, de compuestos de tipo fenólico (ácidos cinámicos, flavonoides, isoflavonoides, deoxiantocianinas, estilbenos, cumarinas, cromonas. Se señala la relación entre el balance hidrófilo-lipófilo y la actividad como fitoalexinas. Finalmente se recogen trabajos sobre la obtención de fitoalexinas sintéticas de estructuras similares a las naturales (estilbenos, derivados de epicatequinas de interés comercial como pesticidas, insecticidas o fungicidas.

  13. Response of anaerobic carbon cycling to water table manipulation in an Alaskan rich fen

    Science.gov (United States)

    Kane, E.S.; Chivers, M.R.; Turetsky, M.R.; Treat, C.C.; Petersen, D.G.; Waldrop, M.; Harden, J.W.; McGuire, A.D.

    2013-01-01

    To test the effects of altered hydrology on organic soil decomposition, we investigated CO2 and CH4 production potential of rich-fen peat (mean surface pH = 6.3) collected from a field water table manipulation experiment including control, raised and lowered water table treatments. Mean anaerobic CO2 production potential at 10 cm depth (14.1 ± 0.9 μmol C g−1 d−1) was as high as aerobic CO2 production potential (10.6 ± 1.5 μmol C g−1 d−1), while CH4 production was low (mean of 7.8 ± 1.5 nmol C g−1 d−1). Denitrification enzyme activity indicated a very high denitrification potential (197 ± 23 μg N g−1 d−1), but net NO-3 reduction suggested this was a relatively minor pathway for anaerobic CO2 production. Abundances of denitrifier genes (nirK and nosZ) did not change across water table treatments. SO2-4 reduction also did not appear to be an important pathway for anaerobic CO2 production. The net accumulation of acetate and formate as decomposition end products in the raised water table treatment suggested that fermentation was a significant pathway for carbon mineralization, even in the presence of NO-3. Dissolved organic carbon (DOC) concentrations were the strongest predictors of potential anaerobic and aerobic CO2 production. Across all water table treatments, the CO2:CH4 ratio increased with initial DOC leachate concentrations. While the field water table treatment did not have a significant effect on mean CO2 or CH4 production potential, the CO2:CH4 ratio was highest in shallow peat incubations from the drained treatment. These data suggest that with continued drying or with a more variable water table, anaerobic CO2 production may be favored over CH4 production in this rich fen. Future research examining the potential for dissolved organic substances to facilitate anaerobic respiration, or alternative redox processes that limit the effectiveness of organic acids as substrates in anaerobic metabolism, would help explain additional

  14. Oxygen, carbon, and nutrients in the oligotrophic eastern subtropical North Atlantic

    Directory of Open Access Journals (Sweden)

    P. Kähler

    2010-03-01

    Full Text Available The Beta Triangle, a region of the oligotrophic subtropical eastern North Atlantic Ocean, is notorious for its enigmatic oxygen, carbon, and nitrogen balances, in which nutrient supply is said to explain only a fraction of production necessary for estimated carbon export. Rates of dissolved organic carbon accumulation and dissolved organic nitrogen utilization in surface water and an assessment of oxygen utilized, organic matter consumed, and nitrate and phosphate regenerated in subsurface water, show that conventional production estimates miss substantial shares of biotic production.

    The shallow export of total organic carbon, predominantly dissolved (DOC, by subduction is responsible for about 50–70% of apparent oxygen utilization in subsurface water between the base of the surface layer at ca. 140 m and ca. 195 m depth, but it is insignificant below. Additionally, there is an estimated accumulation of 1.0 to 1.75 mol DOC m−2 a−1 in surface water. Including DOC dynamics in its carbon balance reveals the surface of this ultra-oligotrophic part of the ocean to be net autotrophic.

    Increasing subsurface values of excess nitrogen (DINxs imply the export of nitrogen from surface water stemming from production not exclusively fuelled by new nitrate supplied from below. Total organic nitrogen (almost exclusively dissolved, DON is consumed in the surface layer at a rate estimated at 0.13 to 0.23 mol m−2 a−1. There is no variation in dissolved organic phosphorus (DOP in the same direction. DON utilization thus contributes to the pronounced subsurface DINxs signature.

    DOC export and accumulation are important in the carbon balance in surface and near-surface water. DON utilization and, probably, N2 fixation contribute significant amounts to the nitrogen supply of surface water. These processes can close part of the enigmatic carbon and nitrogen balances in the

  15. Oxygen, carbon, and nutrients in the oligotrophic eastern subtropical North Atlantic

    Directory of Open Access Journals (Sweden)

    P. Kähler

    2009-09-01

    Full Text Available The Beta Triangle, a region of the oligotrophic subtropical eastern North Atlantic Ocean, is notorious for its enigmatic oxygen, carbon, and nitrogen balances, in which nutrient supply is said to explain only a fraction of production necessary for estimated carbon export. Rates of dissolved organic carbon accumulation and dissolved organic nitrogen utilization in surface water and an assessment of oxygen utilized, organic matter consumed, and nitrate and phosphate regenerated in subsurface water, show that conventional production estimates miss substantial shares of biotic production.

    The shallow export of total organic carbon, predominantly dissolved (DOC, by subduction is responsible for about 50–70% of apparent oxygen utilization in subsurface water between the base of the surface layer at ca. 140 m and ca. 195 m depth, but it is insignificant below. Additionally, there is an estimated accumulation of 1.0 to 1.75 mol DOC m−2 a−1 in surface water. Including DOC dynamics in its carbon balance reveals the surface of this ultra-oligotrophic part of the ocean to be autotrophic.

    Subsurface excess nitrogen (DINxs regeneration implies the utilization of nitrogen in surface water in addition to new nitrate supplied from below. Total organic nitrogen (almost exclusively dissolved, DON is consumed in the surface layer at a rate estimated at 0.13 to 0.23 mol m−2 a−1. There is no variation in dissolved organic phosphorus (DOP in the same direction. DON utilization thus contributes to the pronounced subsurface DINxs signature.

    DOC export and accumulation are important in the carbon balance in surface and near-surface water. DON utilization and, probably, N2 fixation contribute significant amounts to the nitrogen supply of surface water. These processes can close part of the enigmatic carbon and nitrogen balances in the Beta Triangle. There are, however, no

  16. Predicting aquatic macrophyte occurrence in soft-water oligotrophic lakes (Pyrenees mountain range

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    Cristina Pulido

    2014-08-01

    Full Text Available Distribution of aquatic macrophytes in lakes is related to geographical, morphological, catchment and water chemistry variables as well as human impacts, which modify the original environment. Here, we aim at building statistical models to establish the ecological niches of 11 aquatic macrophytes (10 different phanerogams and the genus Nitella from oligotrophic soft-water lakes and infer their ecological requirements and environmental constraints at the southernmost limit of their distribution. Macrophyte occurrence and environmental variables were obtained from 86 non-exploited oligotrophic soft-water lakes from the Pyrenees (Southern Europe; 42º50´N, 1º00´E; macrophytes inhabited 55 of these lakes. Optimum ranges and macrophyte occurrence were predicted in relation to 18 geographical, morphological, catchment and water chemistry variables using univariate and multivariate logistic models. Lakes at low altitude, in vegetated catchments and with low water concentration of NO3- and SO4-2, were the most suitable to host macrophytes. In general, individual species of aquatic macrophytes showed clear patterns of segregation along conductivity and pH gradients, although the specific combination of variables selected in the best models explaining their occurrence differed among species.  Based on the species response to pH and conductivity, we found Isoetes lacustris have its optimum in waters with low conductivity and pH (i.e. negative monotonic response. In contrast, Callitriche palustris, Ranunculus aquatilis, Subularia aquatica, Nitella spp., and Myriophyllum alterniflorum showed an optimum at intermediate values (i.e. unimodal response, whereas Potamogeton berchtoldii, Potamogeton alpinus, and Ranunculus trichophyllus as species had their optimum at relatively high water pH and conductivity (i.e. positive monotonic response. This pattern has been observed in other regions for the same species, although with different optima and tolerance

  17. Atributos privativos e musicais do fenômeno noturno

    Directory of Open Access Journals (Sweden)

    Clovis Salgado Gontijo Oliveira Clovis Salgado Gontijo Oliveira

    2015-11-01

    Full Text Available Desde a sua análise como mero fenômeno, elaborada com pretensões de neutralidade, a noite é por nós concebida a partir de atributos predominantemente privativos. Estes se acentuam culturalmente na tradição ocidental, que tende a desvalorizá-los como signos de um vazio de ordem ontológica, epistemológica, ética e, até mesmo, estética. Associadas a uma esfera de negatividade, tais privações parecem impedir ou, pelo menos, dificultar o tratamento artístico da experiência noturna, sobretudo quando este pretende se realizar num modelo de arte em continuidade com uma proposta visual e iluminista. Tomando como base nossa tese de doutorado, intitulada XXX, pretendemos aqui analisar de que modo os atributos privativos referentes à noite não só dificultam a sua mímese quanto estão presentes, sob nova interpretação, em contextos que revalorizam positivamente a experiência noturna, potencializando-a, assim, como motivo. Dentre estes contextos, concederemos particular atenção à arte musical, que, coincidentemente, manifesta para o teórico e o ouvinte alguns dos mesmos atributos privativos identificados na análise primária do noturno. A fim de efetuar este estudo, recorreremos ao pensamento de Vladimir Jankélévitch, principal fundamentação teórica da tese cujo percurso será sintetizado neste artigo.

  18. Understanding Prairie Fen Hydrology - a Hierarchical Multi-Scale Groundwater Modeling Approach

    Science.gov (United States)

    Sampath, P.; Liao, H.; Abbas, H.; Ma, L.; Li, S.

    2012-12-01

    Prairie fens provide critical habitat to more than 50 rare species and significantly contribute to the biodiversity of the upper Great Lakes region. The sustainability of these globally unique ecosystems, however, requires that they be fed by a steady supply of pristine, calcareous groundwater. Understanding the hydrology that supports the existence of such fens is essential in preserving these valuable habitats. This research uses process-based multi-scale groundwater modeling for this purpose. Two fen-sites, MacCready Fen and Ives Road Fen, in Southern Michigan were systematically studied. A hierarchy of nested steady-state models was built for each fen-site to capture the system's dynamics at spatial scales ranging from the regional groundwater-shed to the local fens. The models utilize high-resolution Digital Elevation Models (DEM), National Hydrologic Datasets (NHD), a recently-assembled water-well database, and results from a state-wide groundwater mapping project to represent the complex hydro-geological and stress framework. The modeling system simulates both shallow glacial and deep bedrock aquifers as well as the interaction between surface water and groundwater. Aquifer heterogeneities were explicitly simulated with multi-scale transition probability geo-statistics. A two-way hydraulic head feedback mechanism was set up between the nested models, such that the parent models provided boundary conditions to the child models, and in turn the child models provided local information to the parent models. A hierarchical mass budget analysis was performed to estimate the seepage fluxes at the surface water/groundwater interfaces and to assess the relative importance of the processes at multiple scales that contribute water to the fens. The models were calibrated using observed base-flows at stream gauging stations and/or static water levels at wells. Three-dimensional particle tracking was used to predict the sources of water to the fens. We observed from the

  19. Differential responses of gut microbiota to the same prebiotic formula in oligotrophic and eutrophic batch fermentation systems

    OpenAIRE

    Wenmin Long; Zhengsheng Xue; Qianpeng Zhang; Zhou Feng; Laura Bridgewater; Linghua Wang; Liping Zhao; Xiaoyan Pang

    2015-01-01

    The same prebiotics have produced inconsistent effects on microbiota when evaluated in different batch fermentation studies. To understand the reasons behind these discrepancies, we compared impact of one prebiotic formula on the same inoculated fecal microbiota in two frequently used batch systems: phosphate-buffered saline (PBS, oligotrophic) and basal culture medium (BCM, eutrophic). The microbiota was monitored using 454 pyrosequencing. Negative controls (no prebiotic) of both systems sho...

  20. Cold-Active, Heterotrophic Bacteria from the Highly Oligotrophic Waters of Lake Vanda, Antarctica

    Directory of Open Access Journals (Sweden)

    Nicole A. Vander Schaaf

    2015-07-01

    Full Text Available The permanently ice-covered lakes of the McMurdo Dry Valleys, Antarctica are distinctive ecosystems that consist strictly of microbial communities. In this study, water samples were collected from Lake Vanda, a stratified Dry Valley lake whose upper waters (from just below the ice cover to nearly 60 m are highly oligotrophic, and used to establish enrichment cultures. Six strains of psychrotolerant, heterotrophic bacteria were isolated from lake water samples from a depth of 50 or 55 m. Phylogenetic analyses showed the Lake Vanda strains to be species of Nocardiaceae, Caulobacteraceae, Sphingomonadaceae, and Bradyrhizobiaceae. All Lake Vanda strains grew at temperatures near or below 0 °C, but optimal growth occurred from 18 to 24 °C. Some strains showed significant halotolerance, but no strains required NaCl for growth. The isolates described herein include cold-active species not previously reported from Dry Valley lakes, and their physiological and phylogenetic characterization broadens our understanding of these limnologically unique lakes.

  1. Polyextremotolerant black fungi: oligotrophism, adaptive potential and a link to lichen symbioses

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    Cene eGostinčar

    2012-11-01

    Full Text Available Black meristematic fungi can survive high doses of radiation and are resistant to desiccation. These adaptations help them to colonize harsh oligotrophic habitats, e.g. on the surface and subsurface of rocks. One of their most characteristic stress-resistance mechanisms is the accumulation of melanin in the cell walls. This, production of other protective molecules and a plastic morphology further contribute to ecological flexibility of black fungi. Increased growth rates of some species after exposure to ionizing radiation even suggest yet unknown mechanisms of energy production. Other unusual metabolic strategies may include harvesting UV or visible light or gaining energy by forming facultative lichen-like associations with algae or cyanobacteria. The latter is not entirely surprising, since certain black fungal lineages are phylogenetically related to clades of lichen-forming fungi. Similar to black fungi, lichen-forming fungi are adapted to growth on exposed surfaces with low availability of nutrients. They also efficiently use protective molecules to tolerate frequent periods of extreme stress. Traits shared by both groups of fungi may have been important in facilitating the evolution and radiation of lichen-symbioses.

  2. Deposition, burial and sequestration of carbon in an oligotrophic, tropical lake

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    Javier Alcocer

    2014-02-01

    Full Text Available The amount of biogenic carbon that may be deposited, buried and eventually preserved (sequestered in the sediments of a tropical, oligotrophic lake, was evaluated based on i the temporal variation of the particulate organic carbon (POC concentration in the superficial sediments in the deep zone of lake Alchichica, Puebla, Mexico; and ii the POC accumulation and preservation in a 210Pb-dated sediment core from the lake. In lake Alchichica the POC concentration in the surficial sediments ranged between 12 and 60 mg POC g-1 (25 ± 12 mg POC g-1 dry weight. The magnitude of the sedimented POC in Alchichica was high and mostly of autochthonous origin. The POC concentrations recorded in the sediment core (16.6 to 31.6 mg g-1 dry weight were comparable to the concentration range observed in the surface sediment samples collected during the study period, which signaled a high POC preservation capacity in the sedimentary column of lake Alchichica. The POC fluxes, estimated from the 210Pb-dated sediment core, varied between 14.9 and 35.3 g m-2 year-1 within the past century; and the maximum POC losses through diagenesis during this period were estimated to be lower than 25%. This study concludes that deep tropical lakes, exemplified by lake Alchichica, accumulate and preserve most of the POC deposited, playing an important role in regional carbon balances.

  3. Bio-optical characterization in an ultra-oligotrophic region: the North central Red Sea

    KAUST Repository

    Kheireddine, Malika

    2015-04-01

    Until recently, satellite-derived ocean color observations have been the only means of evaluating optical variability of the Red Sea. During a cruise in autumn 2014, we investigated the variability of Inherent Optical Properties (IOPs) in the North Central Red Sea (NCRS) with a particular focus on the particulate backscattering coefficient, bbp, and colored dissolved organic matter, CDOM, absorption. To our knowledge, these are some of the measurements of these properties in the Red Sea. The IOPs are derived from the concentration and physical properties of suspended particles in the ocean. They provide a simple description of the influence of these particles on the light within the water column. Bio-optical relationships found for ultra-oligotrophic waters of the six stations sampled significantly depart from the mean standard relationships provided for the global ocean, showing the peculiar character of the Red Sea. These optical anomalies relate to the specific biological and environmental conditions occurring in the Red Sea ecosystem. Specifically, the surface specific phytoplankton absorption coefficients are lower than the values predicted from the global relationships due to a high proportion of relatively large sized phytoplankton. Conversely, bbp values are much higher than the mean standard values for a given chlorophyll-a concentration, Chl a. This presumably results from the influence of highly refractive submicrometer particles of Saharan origin in the surface layer of the water column.

  4. The Biogeochemistry from the Oligotrophic to the Ultraoligotrophic Mediterranean (BOUM experiment

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    T. Moutin

    2011-08-01

    Full Text Available The overall goal of the BOUM (Biogeochemistry from the Oligotrophic to the Ultraoligotrophic Mediterranean experiment was to obtain a better representation of the interactions between planktonic organisms and the cycle of biogenic elements in the Mediterranean Sea (MS, in the context of global climate change and, more particularly, on the role of the ocean in carbon sequestration through biological processes. The BOUM experiment was organized around three main objectives which are: (1 to give a longitudinal description of the biogeochemistry and the biological diversity of the MS during the strongest stratified period, (2 to study processes at the centre of three anticyclonic eddies, and (3 to obtain a representation of the main biogeochemical fluxes and the dynamics of the planktonic trophic network. The international BOUM cruise took place between 16 June and 20 July 2008, involved 32 scientists on board, and covered around 3000 km in the MS from the South of Cyprus to Marseilles (France. This paper describes in detail the objectives of the BOUM experiment, the implementation plan of the cruise, the water masses and general biogeochemical trends encountered, and lays particular emphasis on description of the sections and the main physical characteristics of the three anticyclonic eddies studied, before concluding with first order biogeochemical budgets and a general overview of the 24 other papers published in this special issue.

  5. Introduction to the Biogeochemistry from the Oligotrophic to the Ultraoligotrophic Mediterranean (BOUM experiment

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    T. Moutin

    2012-10-01

    Full Text Available The overall goal of the BOUM (Biogeochemistry from the Oligotrophic to the Ultraoligotrophic Mediterranean experiment was to obtain a better representation of the interactions between planktonic organisms and the cycle of biogenic elements in the Mediterranean Sea (MS, in the context of global climate change and, more particularly, on the role of the ocean in carbon sequestration through biological processes. The BOUM experiment was organized around three main objectives: (1 to give a longitudinal description of the biogeochemistry and the biological diversity of the MS during the strongest stratified period, (2 to study processes at the centre of three anticyclonic eddies, and (3 to obtain a representation of the main biogeochemical fluxes and the dynamics of the planktonic trophic network. The international BOUM cruise took place between 16 June and 20 July 2008, involved 32 scientists on board, and covered around 3000 km in the MS from the south of Cyprus to Marseilles (France. This paper describes in detail the objectives of the BOUM experiment, the implementation plan of the cruise before giving an introduction of the 25 other papers published in this special issue.

  6. Determinants of Paracentrotus lividus sea urchin recruitment under oligotrophic conditions: Implications for conservation management.

    Science.gov (United States)

    Oliva, Silvia; Farina, Simone; Pinna, Stefania; Guala, Ivan; Agnetta, Davide; Ariotti, Pierre Antoine; Mura, Francesco; Ceccherelli, Giulia

    2016-06-01

    Sea urchins may deeply shape the structure of macrophyte-dominated communities and require the implementation of sustainable management strategies. In the Mediterranean, the identification of the major recruitment determinants of the keystone sea urchin species Paracentrotus lividus is required, so that source areas of the populations can be identified and exploitation or programmed harvesting can be spatially managed. In this study a collection of eight possible determinants, these encompassing both the biotic (larvae, adult sea urchins, fish, encrusting coralline algae, habitat type and spatial arrangement of habitats) and abiotic (substrate complexity and nutritional status) realms was considered at different spatial scales (site, area, transect and quadrat). Data from a survey including sites subject to different levels of human influence (i.e. from urbanized to protected areas), but all corresponding to an oligotrophic and low-populated region were fitted by means of a generalized linear mixed model. Despite the extensive sampling effort of benthic quadrats, an overall paucity of recruits was found, recruits being aggregated in a very small number of quadrats and in few areas. The analysis of data detected substrate complexity, and adult sea urchin and predatory fish abundances as the momentous determinants of Paracentrotus lividus recruitment. Possible mechanisms of influence are discussed beyond the implications of conservation management. PMID:27043483

  7. Benthic primary producers are promoted by groundwater-borne nutrient inputs to an oligotrophic lake

    Science.gov (United States)

    Périllon, Cécile; Pöschke, Franziska; Lewandowski, Jörg; Hupfer, Michael; Hilt, Sabine

    2015-04-01

    Nutrient-rich groundwater may contribute significantly to the nutrient influx to lakes. We hypothesized that benthic primary producers may benefit from these nutrients and store them at the sediment-water interface, thus potentially preventing eutrophication processes in the open water. To test this hypothesis, we performed measurements and experiments in the shallow littoral areas of the oligotrophic Lake Stechlin in Germany (4.25 km², maximum depth 70 m). Periphyton grown on artificial substrates for four weeks was sampled at three different locations with groundwater influx and three respective locations without groundwater influx in summer 2013. A comparison between these zones with and without seepage revealed that groundwater discharge increased periphyton dry weight by 56 % and its areal phosphorus accumulation by 41% in 2013. Phosphorus stored in periphyton and macrophytes accounted to up to 46% of the phosphorous present in the epilimnion in summer. In addition, we conducted experiments with flow-through chambers installed in the sediment of an area with intense groundwater influx. We measured seepage, sampled pore water and compared the biomass of periphyton grown on artificial substrate and of submerged macrophytes (Potamogeton pectinatus L.) planted in open and closed-bottom (control) chambers. In open chambers with groundwater influx, periphyton dry weight increased up to 27% and macrophyte growth rate up to 52 % in comparison to closed-bottom chambers.

  8. Can Asian Dust Trigger Phytoplankton Blooms in the Oligotrophic Northern South China Sea?

    Science.gov (United States)

    Wang, Sheng Hsiang; Hsu, Nai-Yung Christina; Tsay, Si-Chee; Lin, Neng-Huei; Sayer, Andrew M.; Huang, Shih-Jen; Lau, William K. M.

    2012-01-01

    Satellite data estimate a high dust deposition flux (approximately 18 g m(exp-2 a(exp-1) into the northern South China Sea (SCS). However, observational evidence concerning any biological response to dust fertilization is sparse. In this study, we combined long-term aerosol and chlorophyll-a (Chl-a) measurements from satellite sensors (MODIS and SeaWiFS) with a 16-year record of dust events from surface PM10 observations to investigate dust transport, flux, and the changes in Chl-a concentration over the northern SCS. Our result revealed that readily identifiable strong dust events over this region, although relatively rare (6 cases since 1994) and accounting for only a small proportion of the total dust deposition (approximately 0.28 g m(exp-2 a(exp-1), do occur and could significantly enhance phytoplankton blooms. Following such events, the Chl-a concentration increased up to 4-fold, and generally doubled the springtime background value (0.15 mg m(exp-3). We suggest these heavy dust events contain readily bioavailable iron and enhance the phytoplankton growth in the oligotrophic northern SCS.

  9. A study on an oligotrophic bacteria and its ecological characteristics in an arid desert area

    Institute of Scientific and Technical Information of China (English)

    PAN HuiXia; CHENG ZhengMing; ZHANG XueMei; MU ShuYong; QI XiaoLing; WANG Fang

    2007-01-01

    An oligotrophic bacterium was isolated from the biological soil crust underlayer in the Xinjiang Gurbantunggut Desert. It was numbered SGB-5, G+. Cell size is (0.328-0.746) μm×(0.171-0.240) μm.Raised colony is white, roundness and its diameter is 5 mm. The strain is a facultative aerobe. It was able to grow in conditions of 1 -15 mg·C·L-1 culture medium at 10-50℃. The strain's optimum growth temperature is 37℃. The range of its optimum growth pH is 8-9. A large amount of extracellular mucopolysaccharide was secreted during growth. The chemical composition of this mucopolysaccharide consists of arabinose, X sugar, glucose, galactose and mannitol. Mole ratio of these sugars is 1:14:19: 6:14. The viscosity of the mucopolysaccharide can reach 6300 mPa·s, when the strain is cultivated for 72 h. After the culture solution in which viscosity was 1500 mPa·s was sprinkled on the quicksand surface, 6 mm bacteria crust of conglutinating sand was formed. This crust could not only stabilize sand, but could also potentially slow the rate of the soil water evaporation.

  10. Fens as Whole-Ecosystem Gauges of Groundwater Recharge Under Climate Change

    Science.gov (United States)

    Drexler, J. Z.; Knifong, D. L.; Tuil, J.; Flint, L. E.; Flint, A. L.

    2011-12-01

    Over the past century, mean air temperature has increased approximately 1 C in California. Since the 1950s, there has been an earlier onset of snowmelt and reduced snowpack (measured as snow water equivalent) in California as well as in much of the western United States. Because the snowpack is the main source of groundwater recharge in the mountainous west, reduced snowpack could result in decreased groundwater recharge through time. This could have important ramifications because groundwater recharge maintains groundwater springs, soil moisture, river baseflows and cool water temperatures. Reductions in groundwater recharge could not only impact water availability for human populations, but could also threaten long-term viability of ecosystems reliant on groundwater flows. Groundwater-fed peatlands called fens are potentially ideal ecosystems for studying changes in groundwater recharge, because they are groundwater discharge sites that rely upon corresponding recharge sites for their sustenance. When the amount of groundwater flow to a fen is reduced, the elevation of the water table decreases leading to desiccation, compaction and increased microbial oxidation of the organic soil. In cases where groundwater flow is reduced over an extended period of time, conversion of fen into wet or mesic meadow or even pine forest can occur resulting in contraction of fen boundaries. The purpose of this study is to evaluate the usefulness of fens as whole-ecosystem gauges of groundwater recharge. We studied 7 fens distributed throughout the Sierra Nevada by tracking their areas over 70+ years with aerial photography. All photos were geo-registered using the 2005 National Agricultural Inventory Program orthophotography as the base. Images were projected to UTM zone 10, NAD 83 using ArcGIS 10.0. Fen vegetation was identified in the aerial photos predominantly by (1) dark brownish-green coloring (or various shades of gray and black in black and white imagery) and (2) mottling

  11. Complex microbiota of a Chinese "Fen" liquor fermentation starter (Fen-Daqu), revealed by culture-dependent and culture-independent methods

    NARCIS (Netherlands)

    Zheng, X.; Zheng, Y.; Han, B.; Zwietering, M.H.; Samson, R.A.; Boekhout, T.; Nout, M.J.R.

    2012-01-01

    Daqu is a traditional fermentation starter that is used for Chinese liquor production. Although partly mechanized, its manufacturing process has remained traditional. We investigated the microbial diversity of Fen-Daqu, a starter for light-flavour liquor, using combined culture-dependent and culture

  12. Complex microbiota of a Chinese "Fen" liquor fermentation starter (Fen-Daqu), revealed by culture-dependent and culture-independent methods

    NARCIS (Netherlands)

    Zheng, X.W.; Yan, Z.; Han, B.Z.; Zwietering, M.H.; Samson, R.A.; Boekhout, T.; Nout, M.J.R.

    2012-01-01

    Daqu is a traditional fermentation starter that is used for Chinese liquor production. Although partly mechanized, its manufacturing process has remained traditional. We investigated the microbial diversity of Fen- Daqu, a starter for light-flavour liquor, using combined culture-dependent and cultur

  13. Phase transformations in interstitial Fe-N alloys

    Energy Technology Data Exchange (ETDEWEB)

    Liapina, T.

    2005-04-15

    Nitriding is a prominent thermochemical heat-treatment procedure leading to various types of surface property improvements of the treated iron and steel. Many questions regarding even very basic properties of these compound layers and the relevant nitride phases are still open. Some of these open questions related with the behaviour of iron nitrides and, in particular, of iron nitride compound layers occurring below the usual process temperatures are addressed to in this thesis, as relevant e.g. for the cooling procedure after nitriding. The most important iron nitrides occurring in iron-nitride compound layers are the {gamma}'- and {epsilon}-phases in the Fe-N system. It is shown that for relatively low nitrogen contents of epsilon-iron nitrides (around Fe{sub 3}N) the cooling rate upon going down from an elevated annealing temperature to room temperature has a significant effect on the lattice parameters. X-ray and neutron diffraction analysis revealed that the lattice parameter values observed after fast cooling are affected by the higher degree of nitrogen disorder at elevated temperature, thus changing the c/a ratio. New relations between the lattice parameters of {epsilon}-iron nitrides and the nitrogen content are suggested for different types of cooling. The investigation by TEM of the decomposition upon annealing (633 K, 673 K) of initially homogeneous {epsilon}-Fe{sub 3}N powders revealed that the {gamma}'-formation occurs in only a few powder particles in a grain-like form. Moreover, diffraction line-profile analysis revealed N transport occurring from particle to particle, leading to inhomogeneities of N content in the epsilon-phase. It was shown that {gamma}'-iron nitride formation can occur by backwards growth of the existing {gamma}'-sublayer at the cost of the {epsilon}-sublayer increasing N concentration in the {epsilon}-layer. Another process, which may additionally occur in the compound layer upon annealing, is diffusion of N

  14. Modeling mountainous fens water regime using 18-O.

    Science.gov (United States)

    Anda, Martin Å.; Ípová, Dora Å.; Dohnal, Michal; Císlerová, Milena

    2010-05-01

    Mountainous fens are important hydrological component of the headwater catchments in Jizera Mountains, The Czech Republic. Experimental catchment Uhlířská (1.78 km2) is formed by paleozolic crystalline bedrock overlaid by shallow highly permeable Cambisol on the hillslopes, whereas the thick saturated glacial deposits in the valley are overlaid by Histosols. Standard meteorological and hydrological monitoring is supplemented by measurements of the soil moisture, soil pore water suction, water table fluctuation in the saturated riparian zone of Černá Nisa creek. Water sampling for the 18O and 2H isotopes is performed throughout the catchment. Numerical simulation was performed with S1D code for the period May 2007-September 2008. The model is based on Richards' equation for vertical soil water flow and the advection-dispersion equation for transport of stable oxygen isotope 18O. Hourly rainfall or daily snowmelt intensities are introduced as an upper boundary condition, the measured groundwater table fluctuation serves as a time variable prescribed head at the bottom boundary. The intensity of the root water uptake due to transpiration is assumed as a zone sink term. Daily values of δ18O in the rain and weekly δ18O values of the melting snow, together with the hourly interpolated monthly values of δ18O in the groundwater, serve as the transport boundary conditions. Measured soil hydraulic parameters were adjusted based on suction heads and δ18O variations in observation points representing the soil tensiometers and suction cups. Results of the model demonstrate a strong mixing of water in the root zone of the peat profile, where evapotranspiration takes place. Process of deeper percolation is limited by the high degree of saturation of the peat in combination with its low hydraulic conductivity. The seasonal water percolation is estimated according to the results of the isotope transport down to 70 cm below the surface. The S1D model with the use of

  15. Fenómeno de Raynaud Raynaud's Phenomenon

    Directory of Open Access Journals (Sweden)

    Ivone Silva

    2011-03-01

    Full Text Available O Fenómeno de Raynaud (FR é uma manifestação clínica comum, traduzida por vasoespasmos recorrentes dos dedos, na maioria das vezes provocados pela exposição ao frio ou estímulos emocionais. Pode ser primário (idiopática ou secundária a diversas doenças ou condições, incluindo doenças do tecido conjuntivo, como esclerose sistémica. A patogênese da FR é mal compreendido. Actualmente pensa-se que a lesão endotelial e a disfunção vascular associada podem ser as primeiras alteração patogénicas e responsável pelas complicações vasculares nos doentes com RP. As alterações funcionais (vasoconstrição e as mudanças estruturais (proliferação intimal e obstrução dos capilares e artérias, traduzem-se clinicamente como RP e úlceras digitais. O FR é em muitos casos a primeira manifestação da doença secundária associado e precede as outras manifestações clínicas em anos.Raynaud´s Phenomenon (RP is a common clinical disorder, manifested by recurrent vasospasm of fingers and toes, often triggered by exposure to cold temperatures or emotional stress. It can be primary (idiopathic or secondary to several diseases or conditions, including connective tissue diseases such as systemic sclerosis. The pathogenesis of RP is poorly understood. It is generally accepted that endothelial damage and vascular dysfunction may be the earliest pathogenetic alteration and ethological factor responsible for vascular complications in RP patients. Functional abnormalities (vasoconstriction and structural changes (intimal proliferation, obstruction are expressed clinically as RP and digital ulcers. RP is the first manifestation of the secondary associated disease and precedes other clinical manifestations by years.

  16. Fenômeno de Raynaud Raynaud's phenomenon

    Directory of Open Access Journals (Sweden)

    Cristiane Kayser

    2009-02-01

    Full Text Available O fenômeno de Raynaud (FRy caracteriza-se por episódios reversíveis de vasoespasmos de extremidades, associados a palidez, seguido por cianose e rubor de mãos e pés, que ocorrem usualmente após estresse ou exposição ao frio. O FRy primário é um evento funcional benigno e não está associado a nenhuma doença ou condição subjacente. Já o FRy secundário pode estar associado a uma série de condições, principalmente a doenças reumáticas autoimunes. Na esclerose sistêmica (ES, o FRy é a manifestação inicial mais frequente. No FRy secundário às doenças do espectro da ES, complicações como lesões isquêmicas de extremidades são frequentes. Nos últimos anos, avanços no estudo da fisiopatologia do FRy e da doença vascular na ES propiciaram o surgimento de opções terapêuticas bastante promissoras para essa manifestação. Nesta revisão pretendemos discorrer principalmente sobre a patogênese, a investigação clínica e o tratamento do FRy, com ênfase nos novos tratamentos disponíveis.Raynaud's phenomenon (RP is an episodic vasospasm of the peripheral arterioles, causing pallor followed by cyanosis and redness of the fingers and toes, usually in response to stress or cold exposure. Primary Raynaud's phenomenon is a benign event and occurs without an underlying disease. In contrast, secondary Raynaud's phenomenon can occur in association with several underlying diseases or conditions, mostly autoimmune rheumatic diseases. In systemic sclerosis (SSc, RP is the most frequent initial manifestation. In RP secondary to SSc-related diseases, digital ischemic lesions are a frequent problem. In recent years, advances in the understanding of the physiopathology of RP have favored the development of novel promising therapeutic alternatives for this clinical condition. This article presents a review of the pathogenesis, clinical investigation and treatment of RP, with special emphasis in novel therapeutic modalities.

  17. Viscosities of FenO-MgO-SiO2 and FenO-MgO-CaO-SiO2 slags

    Institute of Scientific and Technical Information of China (English)

    戴曦; 甘雪萍; 张传福

    2003-01-01

    The viscosities of molten Fen O-MgO-SiO2 and Fen O-MgO-CaO-SiO2 semi-synthetic slags for nickel flash smelting were mearured in the temperature range of 1 200-1 450℃ by use of a rotational viscometer.The mass ratio of Fe to SiO2 was fixed at 1.2,calcium oxide and magnesium oxide contents varied in the range of 2%-8% and 9%-12%(mass fraction),respectively.The results show that silicate anions become smaller by increasing CaO content,which results in the viscosity decrease of slag.In the case of addition of MgO the viscosity behaviour is complicated When MgO content is less than 11%,the viscosity increases with the increase of MgO at all temperatures tested .However,when the MgO content is more than 11%,the viscosity decreases slightly for Fen O-MgO-CaOSiO2 system.At higher MgO contents,low-viscosity slags can be obtained by adding CaO.As for a given composition,the viscosity decreased with increasing temperature.The higher the temperature,the more MgO can be added before saturation.The effect of Fe3 O4 on the viscosity is quite significant.The viscosity of slag increases to 300 mpa tions of temperature and composition.A comparison between Fen O-MgO-SiO2 and Fen O-MgO-CaO-SiO2 systems are also given.

  18. Actividad antioxidante de los compuestos fenólicos

    OpenAIRE

    Maestro Durán, R.; Borja Padilla, R.

    1993-01-01

    This review deals with the oxidation processes induced by light and atmospheric oxygen, as well as the protective action on antioxidant compounds. The available data on the synthetic antioxidants and the problems associated to their use, together with the presence of natural phenolic antioxidants in plants, have been revised. These phenolic antioxidants have been classified in families: phenolic alcohols and acids, cinnamic acids, coumarins, favonoids (flavones and isoflavones, flavonols, fla...

  19. Nitrogen cycling in the subsurface biosphere: nitrate isotopes in porewaters underlying the oligotrophic North Atlantic

    Directory of Open Access Journals (Sweden)

    S. D. Wankel

    2015-08-01

    Full Text Available Nitrogen (N is a key component of fundamental biomolecules. Hence, the cycling and availability of N is a central factor governing the extent of ecosystems across the Earth. In the organic-lean sediment porewaters underlying the oligotrophic ocean, where low levels of microbial activity persist despite limited organic matter delivery from overlying water, the extent and modes of nitrogen transformations have not been widely investigated. Here we use the N and oxygen (O isotopic composition of porewater nitrate (NO3− from a site in the oligotrophic North Atlantic (IODP to determine the extent and magnitude of microbial nitrate production (via nitrification and consumption (via denitrification. We find that NO3− accumulates far above bottom seawater concentrations (∼ 21 μM throughout the sediment column (up to ∼ 50 μM down to the oceanic basement as deep as 90 mbsf, reflecting the predominance of aerobic nitrification/remineralization within the deep marine sediments. Large changes in the δ15N and δ18O of nitrate, however, reveal variable influence of nitrate respiration across the three sites. We use an inverse porewater diffusion–reaction model, constrained by the N and O isotope systematics of nitrification and denitrification and the porewater NO3− isotopic composition, to estimate rates of nitrification and denitrification throughout the sediment column. Results indicate variability of reaction rates across and within the three boreholes that are generally consistent with the differential distribution of dissolved oxygen at this site, though not necessarily with the canonical view of how redox thresholds separate nitrate regeneration from dissimilative consumption spatially. That is, we provide isotope evidence for expanded zones of co-ocurring nitrification and denitrification. The isotope biogeochemical modeling also yielded estimates for the δ15N and δ18O of newly produced nitrate (δ15NNTR and δ18ONTR, as well as the

  20. Influence of anticyclonic eddies on the Biogeochemistry from the Oligotrophic to the Ultraoligotrophic Mediterranean (BOUM cruise

    Directory of Open Access Journals (Sweden)

    T. Moutin

    2012-10-01

    Full Text Available We studied a longitudinal transect in the Mediterranean Sea (MS and along this transect, the influence of anticyclonic eddies at three long duration (LD stations. The deep chlorophyll maximum depth, the euphotic layer depth and the top of the nitracline depth are clearly correlated outside of the eddies, and deepen from the oligotrophic western to the ultraoligotrophic eastern MS. We provide evidence that the locations of the three LD stations studied were near the axis of the eddies. Their diameters were close to 100 km and the studied areas were less than 10 km from the centre of the eddies. The positions of the LD stations are marked by an increase in the flux function and a decrease in apparent oxygen utilization (AOU and in excess density σ, as expected for anticyclonic eddies. Integrated mean primary production measured in situ inside the three studied eddies confirms the previous conclusion that integrated primary production (IPP about 150 mgC m−2 d−1 may appear as a lower limit for IPP during strong oligotrophic conditions. The mesoscale activity is strong enough to locally modify the very well-documented western-to-eastern gradient of trophic conditions in the MS. We proposed a new calculation for mixed layer depths (MLDs enabling the determination of MLD to take into consideration processes occurring with time scales ranging from a few hours to several days, and also the winter MLD. Studying the main physical, chemical and dynamical characteristics of the three eddies enables us to consider that the vorticity barrier prevents any strong mixing and advection of outer water inside the eddy and explains why the depth range of eddies starts from the surface. As a first approximation, the anticyclonic eddies could be considered as closed systems dating back to the previous winter, making possible to draw first-order budgets. The daily new N-input in the photic zone is virtually identical to the N-export measured

  1. Nitrogen cycling in the deep sedimentary biosphere: nitrate isotopes in porewaters underlying the oligotrophic North Atlantic

    Science.gov (United States)

    Wankel, S. D.; Buchwald, C.; Ziebis, W.; Wenk, C. B.; Lehmann, M. F.

    2015-12-01

    Nitrogen (N) is a key component of fundamental biomolecules. Hence, its cycling and availability are central factors governing the extent of ecosystems across the Earth. In the organic-lean sediment porewaters underlying the oligotrophic ocean, where low levels of microbial activity persist despite limited organic matter delivery from overlying water, the extent and modes of nitrogen transformations have not been widely investigated. Here we use the N and oxygen (O) isotopic composition of porewater nitrate (NO3-) from a site in the oligotrophic North Atlantic (Integrated Ocean Drilling Program - IODP) to determine the extent and magnitude of microbial nitrate production (via nitrification) and consumption (via denitrification). We find that NO3- accumulates far above bottom seawater concentrations (~ 21 μM) throughout the sediment column (up to ~ 50 μM) down to the oceanic basement as deep as 90 m b.s.f. (below sea floor), reflecting the predominance of aerobic nitrification/remineralization within the deep marine sediments. Large changes in the δ15N and δ18O of nitrate, however, reveal variable influence of nitrate respiration across the three sites. We use an inverse porewater diffusion-reaction model, constrained by the N and O isotope systematics of nitrification and denitrification and the porewater NO3- isotopic composition, to estimate rates of nitrification and denitrification throughout the sediment column. Results indicate variability of reaction rates across and within the three boreholes that are generally consistent with the differential distribution of dissolved oxygen at this site, though not necessarily with the canonical view of how redox thresholds separate nitrate regeneration from dissimilative consumption spatially. That is, we provide stable isotopic evidence for expanded zones of co-occurring nitrification and denitrification. The isotope biogeochemical modeling also yielded estimates for the δ15N and δ18O of newly produced nitrate (

  2. Nitrogen cycling in the subsurface biosphere: nitrate isotopes in porewaters underlying the oligotrophic North Atlantic

    Science.gov (United States)

    Wankel, S. D.; Buchwald, C.; Ziebis, W.; Wenk, C. B.; Lehmann, M. F.

    2015-08-01

    Nitrogen (N) is a key component of fundamental biomolecules. Hence, the cycling and availability of N is a central factor governing the extent of ecosystems across the Earth. In the organic-lean sediment porewaters underlying the oligotrophic ocean, where low levels of microbial activity persist despite limited organic matter delivery from overlying water, the extent and modes of nitrogen transformations have not been widely investigated. Here we use the N and oxygen (O) isotopic composition of porewater nitrate (NO3-) from a site in the oligotrophic North Atlantic (IODP) to determine the extent and magnitude of microbial nitrate production (via nitrification) and consumption (via denitrification). We find that NO3- accumulates far above bottom seawater concentrations (∼ 21 μM) throughout the sediment column (up to ∼ 50 μM) down to the oceanic basement as deep as 90 mbsf, reflecting the predominance of aerobic nitrification/remineralization within the deep marine sediments. Large changes in the δ15N and δ18O of nitrate, however, reveal variable influence of nitrate respiration across the three sites. We use an inverse porewater diffusion-reaction model, constrained by the N and O isotope systematics of nitrification and denitrification and the porewater NO3- isotopic composition, to estimate rates of nitrification and denitrification throughout the sediment column. Results indicate variability of reaction rates across and within the three boreholes that are generally consistent with the differential distribution of dissolved oxygen at this site, though not necessarily with the canonical view of how redox thresholds separate nitrate regeneration from dissimilative consumption spatially. That is, we provide isotope evidence for expanded zones of co-ocurring nitrification and denitrification. The isotope biogeochemical modeling also yielded estimates for the δ15N and δ18O of newly produced nitrate (δ15NNTR and δ18ONTR), as well as the isotope effect for

  3. Trichodesmium genome maintains abundant, widespread noncoding DNA in situ, despite oligotrophic lifestyle

    Energy Technology Data Exchange (ETDEWEB)

    Walworth, Nathan G.; Pfreundt, Ulrike; Nelson, William C.; Mincer, Tracy; Heidelberg, John F.; Fu, Feixue; Waterbury, John B.; Glavina del Rio, T.; Goodwin, Lynne A.; Kyrpides, Nikos; Land, Miriam L.; Woyke, Tanja; Hutchins, David A.; Hess, Wolfgang R.; Webb, Eric A.

    2015-04-07

    Understanding the evolution of the free-living, cyanobacterial, diazotroph Trichodesmium is of great importance due to its critical role in oceanic biogeochemistry and primary production. Unlike the other >150 available genomes of free-living cyanobacteria, only 63.8% of the Trichodesmium erythraeum (strain IMS101) genome is predicted to encode protein, which is 20-25% less than the average for other cyanobacteria and non-pathogenic, free-living bacteria. We use distinctive isolates and metagenomic data to show that low coding density observed in IMS101 is a common feature of the Trichodesmium genus both in culture and in situ. Transcriptome analysis indicates that 86% of the non-coding space is expressed, although the function of these transcripts is unclear. The density of noncoding, possible regulatory elements predicted in Trichodesmium, when normalized per intergenic kilobase, was comparable and two fold higher than that found in the gene dense genomes of the sympatric cyanobacterial genera Synechococcus and Prochlorococcus, respectively. Conserved Trichodesmium ncRNA secondary structures were predicted between most culture and metagenomic sequences lending support to the structural conservation. Conservation of these intergenic regions in spatiotemporally separated Trichodesmium populations suggests possible genus-wide selection for their maintenance. These large intergenic spacers may have developed during intervals of strong genetic drift caused by periodic blooms of a subset of genotypes, which may have reduced effective population size. Our data suggest that transposition of selfish DNA, low effective population size, and high fidelity replication allowed the unusual ‘inflation’ of noncoding sequence observed in Trichodesmium despite its oligotrophic lifestyle.

  4. Microbial methane production in oxygenated water column of an oligotrophic lake.

    Science.gov (United States)

    Grossart, Hans-Peter; Frindte, Katharina; Dziallas, Claudia; Eckert, Werner; Tang, Kam W

    2011-12-01

    The prevailing paradigm in aquatic science is that microbial methanogenesis happens primarily in anoxic environments. Here, we used multiple complementary approaches to show that microbial methane production could and did occur in the well-oxygenated water column of an oligotrophic lake (Lake Stechlin, Germany). Oversaturation of methane was repeatedly recorded in the well-oxygenated upper 10 m of the water column, and the methane maxima coincided with oxygen oversaturation at 6 m. Laboratory incubations of unamended epilimnetic lake water and inoculations of photoautotrophs with a lake-enrichment culture both led to methane production even in the presence of oxygen, and the production was not affected by the addition of inorganic phosphate or methylated compounds. Methane production was also detected by in-lake incubations of lake water, and the highest production rate was 1.8-2.4 nM⋅h(-1) at 6 m, which could explain 33-44% of the observed ambient methane accumulation in the same month. Temporal and spatial uncoupling between methanogenesis and methanotrophy was supported by field and laboratory measurements, which also helped explain the oversaturation of methane in the upper water column. Potentially methanogenic Archaea were detected in situ in the oxygenated, methane-rich epilimnion, and their attachment to photoautotrophs might allow for anaerobic growth and direct transfer of substrates for methane production. Specific PCR on mRNA of the methyl coenzyme M reductase A gene revealed active methanogenesis. Microbial methane production in oxygenated water represents a hitherto overlooked source of methane and can be important for carbon cycling in the aquatic environments and water to air methane flux.

  5. Groups without cultured representatives dominate eukaryotic picophytoplankton in the oligotrophic South East Pacific Ocean.

    Directory of Open Access Journals (Sweden)

    Xiao Li Shi

    Full Text Available BACKGROUND: Photosynthetic picoeukaryotes (PPE with a cell size less than 3 microm play a critical role in oceanic primary production. In recent years, the composition of marine picoeukaryote communities has been intensively investigated by molecular approaches, but their photosynthetic fraction remains poorly characterized. This is largely because the classical approach that relies on constructing 18S rRNA gene clone libraries from filtered seawater samples using universal eukaryotic primers is heavily biased toward heterotrophs, especially alveolates and stramenopiles, despite the fact that autotrophic cells in general outnumber heterotrophic ones in the euphotic zone. METHODOLOGY/PRINCIPAL FINDINGS: In order to better assess the composition of the eukaryotic picophytoplankton in the South East Pacific Ocean, encompassing the most oligotrophic oceanic regions on earth, we used a novel approach based on flow cytometry sorting followed by construction of 18S rRNA gene clone libraries. This strategy dramatically increased the recovery of sequences from putative autotrophic groups. The composition of the PPE community appeared highly variable both vertically down the water column and horizontally across the South East Pacific Ocean. In the central gyre, uncultivated lineages dominated: a recently discovered clade of Prasinophyceae (IX, clades of marine Chrysophyceae and Haptophyta, the latter division containing a potentially new class besides Prymnesiophyceae and Pavlophyceae. In contrast, on the edge of the gyre and in the coastal Chilean upwelling, groups with cultivated representatives (Prasinophyceae clade VII and Mamiellales dominated. CONCLUSIONS/SIGNIFICANCE: Our data demonstrate that a very large fraction of the eukaryotic picophytoplankton still escapes cultivation. The use of flow cytometry sorting should prove very useful to better characterize specific plankton populations by molecular approaches such as gene cloning or metagenomics

  6. Effects of oligotrophication on primary production in peri-alpine lakes

    Science.gov (United States)

    Finger, David; Wüest, Alfred; Bossard, Peter

    2013-08-01

    During the second half of the 20th century untreated sewage released from housing and industry into natural waters led to a degradation of many freshwater lakes and reservoirs worldwide. In order to mitigate eutrophication, wastewater treatment plants, including Fe-induced phosphorus precipitation, were implemented throughout the industrialized world, leading to reoligotrophication in many freshwater lakes. To understand and assess the effects of reoligotrophication on primary productivity, we analyzed 28 years of 14C assimilation rates, as well as other biotic and abiotic parameters, such as global radiation, nutrient concentrations and plankton densities in peri-alpine Lake Lucerne, Switzerland. Using a simple productivity-light relationship, we estimated continuous primary production and discussed the relation between productivity and observed limnological parameters. Furthermore, we assessed the uncertainty of our modeling approach based on monthly 14C assimilation measurements using Monte Carlo simulations. Results confirm that monthly sampling of productivity is sufficient for identifying long-term trends in productivity and that conservation management has successfully improved water quality during the past three decades via reducing nutrients and primary production in the lake. However, even though nutrient concentrations have remained constant in recent years, annual primary production varies significantly from year to year. Despite the fact that nutrient concentrations have decreased by more than an order of magnitude, primary production has decreased only slightly. These results suggest that primary production correlates well to nutrients availability but meteorological conditions lead to interannual variability regardless of the trophic status of the lake. Accordingly, in oligotrophic freshwaters meteorological forcing may reduce productivity impacting on the entire food chain of the ecosystem.

  7. Photochemical production of ammonium in the oligotrophic Cyprus Gyre (Eastern Mediterranean

    Directory of Open Access Journals (Sweden)

    V. Kitidis

    2006-06-01

    Full Text Available We investigated the photoproduction of ammonium (NH4+ in surface waters of the Cyprus gyre in the central Eastern Mediterranean in May 2002, in 8 on deck irradiations with freshly collected, filtered samples. NH4+ photoproduction (photoammonification increased with time-integrated irradiance during the course of irradiations. Photoammonification rates around local noon were 0.4–2.9 nmol L−1 h−1. Normalised to time integrated irradiance, these rates were 0.9–3.8 pmol L−1 h−1/(W m−2 and were significantly correlated with Chromophoric Dissolved Organic Matter (CDOM absorbance at 300 nm normalised to Dissolved Organic Carbon (DOC. These results are consistent with the notion that successive CDOM photobleaching in the surface mixed layer results in decreased DOC-normalised light absorbance concurrent with decreased dissolved organic matter reactivity with regard to photochemical NH4+ release. Combining our experimental data with estimates of annual solar irradiance and water column light attenuation yields an annual photoammonification rate for the Cyprus Gyre of 40±17 mmol m−2 a−1, equivalent to ~12±5% of the previously estimated annual nitrogen requirement of new production in this region. Based on this analysis, NH4+ photoproduction makes a small, but significant contribution to the nitrogen budget of the euphotic zone in the oligotrophic Cyprus Gyre.

  8. Enrichment experiment changes microbial interactions in an ultra-oligotrophic environment

    Directory of Open Access Journals (Sweden)

    Gabriel Yaxal Ponce-Soto

    2015-04-01

    Full Text Available The increase of nutrients in water bodies, in particular nitrogen (N and phosphorus (P due to the recent expansion of agricultural and other human activities is accelerating environmental degradation of these water bodies, elevating the risk of eutrophication and reducing biodiversity. To evaluate the ecological effects of the influx of nutrients in an oligotrophic and stoichiometrically imbalanced environment, we performed a replicated in situ mesocosm experiment. We analyzed the effects of a N- and P-enrichment on the bacterial interspecific interactions in an experiment conducted in the Cuatro Cienegas Basin (CCB in Mexico. This is a desert ecosystem comprised of several aquatic systems with a large number of microbial endemic species. The abundance of key nutrients in this basin exhibits strong stoichiometric imbalance (high N:P ratios, suggesting that species diversity is maintained mostly by competition for resources. We focused on the biofilm formation and antibiotic resistance of 960 strains of cultivated bacteria in two habitats, water and sediment, before and after three weeks of fertilization. The water habitat was dominated by Pseudomonas, while Halomonas dominated the sediment. Strong antibiotic resistance was found among the isolates at time zero in the nutrient-poor bacterial communities, but resistance declined in the bacteria isolated in the nutrient-rich environments, suggesting that in the nutrient-poor original environment, negative inter-specific interactions were important, while in the nutrient-rich environments, competitive interactions are not so important. In water, a significant increase in the percentage of biofilm-forming strains was observed for all treatments involving nutrient addition.

  9. Variations in ectoenzymatic hydrolytic activity in an oligotrophic environment (Southern Tyrrhenian Sea, W Mediterranean)

    Science.gov (United States)

    Misic, Cristina; Castellano, Michela; Ruggieri, Nicoletta; Harriague, Anabella Covazzi

    2008-09-01

    The variations in the expression of two hydrolytic ectoenzymes (leucine aminopeptidase - LA - and β glucosidase — BG) were studied in the southern Tyrrhenian Sea during spring 2004. This area is characterised by a complex morphology and hydrodynamism, which generate significant differences between different sectors, particularly in the 0-100 m layer. However, the area generally exhibits oligotrophic features such as low autotrophic pigment and organic matter concentrations and a higher bacterial biomass than the phytoplanktonic one. Despite this general bottom-up pressure, adaptations by the microbial consumers were indicated by the ectoenzymatic activities and by the relationships between the enzymes, their organic substrates and their producers (namely the bacteria). In particular, bacteria were able to exploit the inorganic N supply (nitrite + nitrate provided by irregular intrusions of intermediate waters) to escape the bottom-up limitation and produce enzymes such as BG devoted to the degradation of cellulose remnants and, therefore, also able to take advantage on this refractory organic matter. In the 200-800 m layer, where trophic limitation was strong due to the low values of potentially-labile organic matter (namely proteins), the peculiar hydrodynamism led to the formation of nepheloid layers rich in organic matter, which provided the bacteria with substrates and allowed the development of a significant correlation between LA activity and its own organic substrate. Furthermore, a reduction of the bottom-up pressure was also indicated by a higher mean bacteria cell size in the entire water column of the central and eastern sectors, and a significantly increased expression of BG related to the increase in the cell size. The ectoenzymatic activities, therefore, suggested that the southern Tyrrhenian Sea should be considered as a mosaic of subsystems, where the peculiar hydrological features stimulate bacterial adaptations and enhance the channelling of

  10. Enrichment experiment changes microbial interactions in an ultra-oligotrophic environment.

    Science.gov (United States)

    Ponce-Soto, Gabriel Y; Aguirre-von-Wobeser, Eneas; Eguiarte, Luis E; Elser, James J; Lee, Zarraz M-P; Souza, Valeria

    2015-01-01

    The increase of nutrients in water bodies, in particular nitrogen (N) and phosphorus (P) due to the recent expansion of agricultural and other human activities is accelerating environmental degradation of these water bodies, elevating the risk of eutrophication and reducing biodiversity. To evaluate the ecological effects of the influx of nutrients in an oligotrophic and stoichiometrically imbalanced environment, we performed a replicated in situ mesocosm experiment. We analyzed the effects of a N- and P-enrichment on the bacterial interspecific interactions in an experiment conducted in the Cuatro Cienegas Basin (CCB) in Mexico. This is a desert ecosystem comprised of several aquatic systems with a large number of microbial endemic species. The abundance of key nutrients in this basin exhibits strong stoichiometric imbalance (high N:P ratios), suggesting that species diversity is maintained mostly by competition for resources. We focused on the biofilm formation and antibiotic resistance of 960 strains of cultivated bacteria in two habitats, water and sediment, before and after 3 weeks of fertilization. The water habitat was dominated by Pseudomonas, while Halomonas dominated the sediment. Strong antibiotic resistance was found among the isolates at time zero in the nutrient-poor bacterial communities, but resistance declined in the bacteria isolated in the nutrient-rich environments, suggesting that in the nutrient-poor original environment, negative inter-specific interactions were important, while in the nutrient-rich environments, competitive interactions are not so important. In water, a significant increase in the percentage of biofilm-forming strains was observed for all treatments involving nutrient addition. PMID:25883593

  11. Diversity of Picoeukaryotes at an Oligotrophic Site off the Northern Red Sea Coast

    KAUST Repository

    Espinosa, Francisco Jose Acosta

    2012-05-01

    Picoeukaryotes are protist 3 µm belonging to a wide diversity of taxonomic groups, and they are an important constituent of the ocean microbiota, performing essential ecological roles in marine trophic chains and in nutrient and carbon budgets. Despite this, the true extent of their diversity is currently unknown, and in the last decade molecular surveys have uncovered a substantial number of previously unknown groups from all taxonomic levels. No studies on this group have been done so far on the Red Sea, a unique marine environment characterized by oligotrophic conditions and high irradiance, salinity and water temperature. We sampled the surface waters of a site near the northern Red Sea coast, and analyzed the picoeukaryotic diversity through the construction of PCR clone libraries using the 18S ribosomal gene. The community captured by our library is dominated by three main groups, the alveolates (32%), chlorophytes (32%) and Stramenopiles (20.55%). Members of Radiolaria, Cercozoans and Haptophyta were also found, although in low abundances. Photosynthetic organisms are especially diverse and abundant in the sample, with heterotrophic organism mostly composed by the mostly parasitic novel alveolates and bacterivorous stramenopiles. Novel clades were detected among the Novel Alveolates- II and the photosynthetic stramenopiles taxa, which suggests that they may be part of a number of groups unique to the basin and adapted to the high salinity and temperature conditions. This is the first study done on the Red Sea focusing on the diversity of the complete picoeukaryotic fraction, and provides a stepping stone in the characterization of the picoeukaryotic component of the microbial diversity of the basin.

  12. Sulfur and carbon isotope biogeochemistry of a rewetted brackish fen

    Science.gov (United States)

    Koebsch, Franziska; Gehre, Matthias; Winkel, Matthias; Koehler, Stefan; Koch, Marian; Jurasinski, Gerald; Spitzy, Alejandro; Liebner, Susanne; Sachs, Torsten; Schmiedinger, Iris; Kretzschmann, Lisett; Saborowski, Anke; Böttcher, Michael E.

    2015-04-01

    Coastal wetlands are at the interface between terrestrial freshwater and marine and exhibit very specific biogeochemical conditions. Intermittent sea water intrusion affects metabolic pathways, i. e. anaerobic carbon metabolism is progressively dominated by sulfate reduction with lower contribution of methanogenesis whilst methane production is increasingly shifted from acetoclastic to hydrogenotrophic. Due to expanding anthropogenic impact a large proportion of coastal ecosystems is degraded with severe implications for the biogeochemical processes. We use concentration patterns and stable isotope signatures of water, sulfate, dissolved carbonate, and methane (δ2H, δ13C, δ18O, δ34S) to investigate the S and C metabolic cycle in a rewetted fen close to the southern Baltic Sea border. Such studies are crucial to better predict dynamic ecosystem feedback to global change like organic matter (OM) decomposition or greenhouse gas emissions. Yet, little is known about the metabolic pathways in such environments. The study site is part of the TERENO Observatory "Northeastern German Lowlands' and measurements of methane emissions have run since 2009. High methane fluxes up to 800 mg m-2 hr-1 indicate that methanogenesis is the dominant C metabolism pathway despite of high sulfate concentrations (up to 37 mM). The presented data are part of a comprehensive biogeochemical investigation that we conducted in autumn 2014 and that comprises 4 pore water profiles and sediment samples within a transect of 300-1500 m distance to the Baltic Sea. Depth of organic layers ranged from 25 to 140 cm with high OM contents (up to 90 dwt.%). Sulfate/chloride ratios in the pore waters were lower than in the Baltic Sea for most sites and sediment depths indicated a substantial net sulfate loss. Sulfide concentrations were negligible at the top and increased parallel to the sulfate concentrations with depth to values of up to 0.3 mM. One pore water profiles situated 1150 m from the Baltic

  13. The identification and optimization of 2,4-diketobutyric acids as flap endonuclease 1 inhibitors.

    Science.gov (United States)

    Tumey, L Nathan; Huck, Bayard; Gleason, Elizabeth; Wang, Jianmin; Silver, Daniel; Brunden, Kurt; Boozer, Sherry; Rundlett, Stephen; Sherf, Bruce; Murphy, Steven; Bailey, Andrew; Dent, Tom; Leventhal, Christina; Harrington, John; Bennani, Youssef L

    2004-10-01

    There have been several recent reports of chemopotentiation via inhibition of DNA repair processes. Flap endonuclease 1 (FEN1) is a key enzyme involved in base excision repair (BER), a primary pathway utilized by mammalian cells to repair DNA damage. In this report, we describe the identification and SAR of a series of 2,4-diketobutyric acid FEN1 inhibitors. PMID:15341951

  14. Examining the peat-accumulating potential of fen vegetation in the context of fed restoration of harvested peatlands

    Energy Technology Data Exchange (ETDEWEB)

    Graf, M.; Rochefort, L. [Laval Univ., Quebec City, PQ (Canada). Dept. de Phytologie, Peatland Ecology and Research Group

    2009-07-01

    The return of peat-accumulating function is an important long-term goal in peatland restoration. However, researchers do not yet know which vegetation groups increase the ability of ecosystems to accumulate peat in fens. This study assessed the decomposition rates of 3 vegetation species typical to undisturbed fen regions, and 3 species that spontaneously colonize harvested fens. All species were incubated in a harvest fen restoration site as well as at an undisturbed fen in order to compare decomposition rates according to different environmental conditions. The study showed that the average exponential decay coefficient for all species was higher at the harvested fen site. The decay coefficient varied only slightly between undisturbed and harvested fens, despite wide variations in hydrological conditions. Litter type had the most significant impact on decomposition rates. Annual primary production of the species was also measured in order to estimate the peat accumulating capacity of each species. Results showed that Scirpus cyperinus primary annual production rates were 3 times higher than the other studied species. It was concluded that the harvested fen sites have a higher peat-accumulating potential than undisturbed fens. 60 refs., 2 tabs., 2 figs.

  15. FORMATION OF Fe-N COMPOUNDS BY LASER NITRIDATION IN AN ATMOSPHERIC AMBIENT

    Institute of Scientific and Technical Information of China (English)

    Y.L. Yang; F.J. Sun; D. Zhang

    2003-01-01

    The formation of Fe-N compounds by laser nitriding in an atmospheric ambient wasreported. By CW-CO2 laser irradiation on pure ferrite iron in the atmospheric am-bient, Fe-N compounds (including Fe2N, Fe3N and Fe4N) are formed as a result of alaser-enhanced and temperature-enhanced reactions. The samples were analyzed withX-ray diffraction. It is found that the laser power density, scanning speed and nitro-gen temperature are the main factors influencing the formation of Fe-N compounds.Nitrogen can be activated by pre-heating at some temperature. Nitrogen activationand sample surface melting by CW-CO2 laser greatly enhance the reaction betweenthe sample surface and nitrogen beam. After annealing at 500℃ for 3h, some Fe2Nand Fe3N converted into more stable Fe4N.

  16. Stream characteristics and their implications for the protection of riparian fens and meadows

    DEFF Research Database (Denmark)

    Baattrup-Pedersen, A.; Larsen, S.E.; Andersen, Peter Mejlhede;

    2011-01-01

    1. Running waters, including associated riparian areas, are embraced by international legal frameworks outlining targets for the preservation, protection and improvement of the quality of the environment. Interactions between stream and river processes and riparian habitats have not received much...... of riparian areas, affecting conditions needed to sustain protected fen and meadow communities. 4. We also found that water chemistry strongly influenced the occurrence of fen and meadow vegetation in riparian areas. The probability of finding fen and meadow vegetation was reduced when total phosphorus (TP...... attention in the management of stream ecosystems, and integrated measures that consider both the ecological status of streams and rivers (sensu EU Water Framework Directive, WFD) and the conservation status of riparian habitats and species (sensu EU Habitats Directive, HD) are rare. 2. Here, we analysed...

  17. Fen1 mutations that specifically disrupt its interaction with PCNA cause aneuploidy-associated cancer

    Institute of Scientific and Technical Information of China (English)

    Li Zheng; Sankar Mitra; Qin Huang; Kemp H Kernstine; Gerd P Pfeifer; Binghui Shen; Huifang Dai; Muralidhar L Hegde; Mian Zhou; Zhigang Guo; Xiwei Wu; Jun WU; Lei Su; Xueyan Zhong

    2011-01-01

    DNA replication and repair are critical processes for all living organisms to ensure faithful duplication and transmission of genetic information. Flap endonuclease 1 (Feni), a structure-specific nuclease, plays an important role in multiple DNA metabolic pathways and maintenance of genome stability. Human FEN1 mutations that impair its exonuclease activity have been linked to cancer development. FEN1 interacts with multiple proteins, including proliferation cell nuclear antigen (PCNA), to form various functional complexes. Interactions with these proteins are considered to be the key molecular mechanisms mediating FEN1's key biological functions. The current challenge is to experimentally demonstrate the biological consequence of a specific interaction without compromising other functions of a desired protein. To address this issue, we established a mutant mouse model harboring a FEN1 point mutation (F343A/F344A, FFAA), which specifically abolishes the FEN1/PCNA interaction. We show that the FFAA mutation causes defects in RNA primer removal and long-patch base excision repair, even in the heterozygous state, resulting in numerous DNA breaks. These breaks activate the G2/M checkpoint protein, Chk1, and induce neartetraploid aneuploidy, commonly observed in human cancer, consequently elevating the transformation frequency. Consistent with this, inhibition of aneupioidy formation by a Chk1 inhibitor significantly suppressed the cellular transformation. WT/FFAA FEN1 mutant mice develop aneuploidy-associated cancer at a high frequency. Thus, this study establishes an exemplary case for investigating the biological significance of protein-protein interactions by knock-in of a point mutation rather than knock-out of a whole gene.

  18. Key players of methane dynamics in alpine fens: interaction of vascular plants and microbial communities

    Science.gov (United States)

    Cheema, S.; Zeyer, J. A.; Henneberger, R.

    2014-12-01

    Natural wetlands are important emitters of the potent greenhouse gas methane (CH4), contributing an estimated 26 - 42% to the global emissions. In these habitats CH4 is generated by methanogenic archaea mediating the terminal steps of organic matter degradation under anoxic conditions. The produced CH4 is partly oxidized by methanotrophic bacteria in oxic zones, thereby mitigating CH4 release. Various factors can influence CH4 emissions from wetlands, including the presence of vascular plants, as their aerenchyma can serve as conduits for CH4 release to the atmosphere. In the present study, we investigated the CH4 dynamics in two Swiss alpine fens (1900 - 2300 m a.s.l), and sampling locations within these fens were characterized by distinct dominant vascular plants, namely Carex spp. and Eriophorum spp.. Analyses of the microbial communities present in the fen soils were complemented by in situ measurements of CH4 emissions and analyses of physico-chemical pore water properties. Methane emissions and pore water concentrations varied depending on fen and dominating plant species, with generally higher CH4 emissions observed from the Carex dominated locations. Active methanotrophic and methanogenic microorganisms (transcripts of specific marker genes) were detected at different depths, independent of O2 and CH4 pore water concentrations. The expected separation of oxic methanotrophic and anoxic methanogenic zones was not observed. Yet, composition analyses of the different communities showed a clear clustering according to fen and dominating plant species. Within each location, variation of composition with depth was only observed for the methanogenic communities. Detailed profiling of CH4 emissions with respect to changes in light and temperature is currently being carried out. Our results represent a comprehensive in situ study on factors affecting CH4 emissions from alpine fens, highlighting the influence of vascular plants on the microbial communities involved.

  19. Diversity of cultivated and metabolically active aerobic anoxygenic phototrophic bacteria along an oligotrophic gradient in the Mediterranean Sea

    Science.gov (United States)

    Jeanthon, C.; Boeuf, D.; Dahan, O.; Le Gall, F.; Garczarek, L.; Bendif, E. M.; Lehours, A.-C.

    2011-07-01

    Aerobic anoxygenic phototrophic (AAP) bacteria play significant roles in the bacterioplankton productivity and biogeochemical cycles of the surface ocean. In this study, we applied both cultivation and mRNA-based molecular methods to explore the diversity of AAP bacteria along an oligotrophic gradient in the Mediterranean Sea in early summer 2008. Colony-forming units obtained on three different agar media were screened for the production of bacteriochlorophyll-a (BChl-a), the light-harvesting pigment of AAP bacteria. BChl-a-containing colonies represented a low part of the cultivable fraction. In total, 54 AAP strains were isolated and the phylogenetic analyses based on their 16S rRNA and pufM genes showed that they were all affiliated to the Alphaproteobacteria. The most frequently isolated strains belonged to Citromicrobium bathyomarinum, and Erythrobacter and Roseovarius species. Most other isolates were related to species not reported to produce BChl-a and/or may represent novel taxa. Direct extraction of RNA from seawater samples enabled the analysis of the expression of pufM, the gene coding for the M subunit of the reaction centre complex of aerobic anoxygenic photosynthesis. Clone libraries of pufM gene transcripts revealed that most phylotypes were highly similar to sequences previously recovered from the Mediterranean Sea and a large majority (~94 %) was affiliated to the Gammaproteobacteria. The most abundantly detected phylotypes occurred in the western and eastern Mediterranean basins. However, some were exclusively detected in the eastern basin, reflecting the highest diversity of pufM transcripts observed in this ultra-oligotrophic region. To our knowledge, this is the first study to document extensively the diversity of AAP isolates and to unveil the active AAP community in an oligotrophic marine environment. By pointing out the discrepancies between culture-based and molecular methods, this study highlights the existing gaps in the understanding

  20. Bathypelagic particle flux signatures from a suboxic eddy in the oligotrophic tropical North Atlantic: production, sedimentation and preservation

    Directory of Open Access Journals (Sweden)

    G. Fischer

    2015-11-01

    Full Text Available Particle fluxes at the Cape Verde Ocean Observatory (CVOO in the eastern tropical North Atlantic for the period December 2009 until May 2011 are discussed based on bathypelagic sediment trap time series data collected at 1290 and 3439 m water depth. The typically oligotrophic particle flux pattern with weak seasonality is modified by the appearance of a highly productive and low oxygen anticyclonic modewater eddy (ACME in winter 2010. The eddy passage was accompanied by unusually high mass fluxes, lasting from December 2009 to May 2010. Distinct biogenic silica (BSi and organic carbon flux peaks were observed in February–March 2010 when the eddy approached CVOO. The flux of the lithogenic component, mostly mineral dust, was well correlated to that of organic carbon in particular in the deep trap samples, suggesting a close coupling. The lithogenic ballasting obviously resulted in high particle settling rates and, thus, a fast transfer of epi-/mesopelagic signatures to the bathypelagic traps. Molar C : N ratios of organic matter during the ACME passage were around 18 and 25 for the upper and lower trap samples, respectively. This suggests that some production under nutrient (nitrate limitation in the upper few tens of meters above the zone of suboxia might have occurred in the beginning of 2010. The δ15N record showed a decrease from January to March 2010 while the organic carbon and N fluxes increased. The causes of enhanced sedimentation from the eddy in February/March 2010 remain elusive but nutrient depletion and/or a high availability of dust as ballast mineral for organic-rich aggregates might have contributed to the elevated fluxes during the eddy passage. Remineralization of sinking organic-rich particles could have contributed to the formation of a suboxic zone at shallow depth. Although the eddy has been formed in the African coastal area in summer 2009, no indication of coastal flux signatures were found in the sediment traps

  1. O fenómeno subversivo na actualidade : contributos para o seu estudo

    OpenAIRE

    Garcia, Francisco Proença

    2006-01-01

    Neste estudo foi utilizada uma perspectiva holística e pluridisciplinar no sentido de alcançar a resposta a uma questão fundamental: “como pode este fenómeno ser caracterizado e apresentado?” tendo sido organizado em quatro partes. A primeira diz respeito ao fenómeno da subversão e às suas características no presente; a segunda parte foca as suas causas e a terceira tenta identificar algumas tipologias possíveis. Por fim, identifica-se e sistematiza- -se as premi...

  2. Fate and Transport of Road Salt During Snowmelt Through a Calcareous Fen: Kampoosa Bog, Stockbridge, Massachusetts

    Science.gov (United States)

    Rhodes, A. L.; Guswa, A. J.; Pufall, A.

    2007-12-01

    Kampoosa Bog is the largest and most ecologically diverse calcareous lake-basin fen in Massachusetts. Situated within a 4.7 km2 drainage basin, the open fen (approx. 20 acres) consists of a floating mat of sedges (incl. Carex aquatilis and Cladium mariscoides) that overlie peat and lake clay deposits. Mineral weathering of marble bedrock within the drainage basin supplies highly alkaline ground and surface waters to the fen basin. The natural chemistry has been greatly altered by road salt runoff from the Massaschusetts Turnpike, and in question is whether disturbance from the Turnpike and a gas pipline has facilitated aggressive growth by the invasive species Phragmites australis. Considered to be one of the most significant rare species habitats in the state, Massachusetts has designated Kampoosa Bog an Area of Critical Environmental Concern, and a committee representing several local, regional, and state agencies, organizations, and citizens manages the wetland. The purpose of this study is to characterize the hydrologic and chemical response of the wetland during snowmelt events to understand the fate and movement of road salt (NaCl). Concentrations of Na and Cl in the fen groundwater are greatest close to the Turnpike. Concentrations decrease with distance downstream but are still greatly elevated relative to sites upstream of the Turnpike. During snowmelt events, the fen's outlet shows a sharp rise in Na and Cl concentrations at the onset of melting that is soon diluted by the added meltwater. The Na and Cl flux, however, is greatest at peak discharge, suggesting that high-flow events are significant periods of export of dissolved salts from the fen. Pure dissolution of rock salt produces an equal molar ratio between Na and Cl, and sodium and chloride imbalances in stream and ground waters suggest that ~20% of the Na is stored on cation exchange sites within the peat. The largest imbalances between Na and Cl occur deeper within the peat, where the peat is

  3. Microbiología alimentaria y fenómenos "paranormales" en la historia

    Directory of Open Access Journals (Sweden)

    José Miguel Soriano del Castillo

    2014-12-01

    Full Text Available A lo largo de la historia han existido fenómenos aparentemente inexplicables cuyos resultados han originado muertes, milagros, juicios por brujería e incluso ganancias y pérdidas de batallas militares. En este artículo se realiza una inspección microbiológica-histórica en donde algunos microorganismos (Claviceps purpurea, Fusarium sporotrichioides, Serratia marcescens y Stachybotrys chartarum, pueden ser los hipotéticos causantes de algunos de estos fenómenos.

  4. Compostos fenólicos totais e taninos condensados em frutas nativas do cerrado

    Directory of Open Access Journals (Sweden)

    Wesley Silveira Rocha

    2011-12-01

    Full Text Available As frutas nativas do cerrado têm despertado ultimamente interesse crescente, devido às suas propriedades nutricionais e funcionais aliadas ao potencial para agregar valor e conservar a biodiversidade deste bioma. Muitos compostos fenólicos apresentam capacidade antioxidante de neutralizar a atividade de radicais livres gerados no organismo, que estão associados a diversas doenças crônico-degenerativas. O objetivo deste trabalho foi avaliar a eficiência de três soluções extratoras (acetona a 70 %, etanol a 95 % e metanol a 99,8 % e determinar os teores de compostos fenólicos em 10 espécies de frutas nativas do cerrado, utilizando o método de Folin-Ciocalteou para compostos fenólicos totais e o método da vanilina para taninos condensados. A acetona a 70 % mostrou-se como o melhor solvente extrator de compostos fenólicos totais e taninos condensados em frutos de Pouteria gardneriana, Eugenia dysenterica, E. klostzchiana, E. punicifolia, Plinia edulis, Campomanesia sp., fenólicos totais de Brosimium gaudichaudii e taninos condensados de Jaracatia spinosa. O etanol a 95 % foi mais eficiente na extração de fenólicos totais de Jaracatia spinosa e taninos condensados de Brosimium gaudichaudii; o metanol a 99,8 % foi mais eficiente na extração de taninos condensados de Eugenia dysenterica. Os teores de compostos fenólicos totais variaram entre 90 e 327 mg de ácido gálico equivalente por 100g de polpa para as espécies E. dysenterica e E. punicifolia, respectivamente. Os teores de taninos condensados variaram entre 4 e 291 mg de catequina equivalente por 100 g de polpa para as espécies E. dysenterica e E. calcyna, respectivamente. As espécies de frutas do cerrado, avaliadas neste estudo, podem ser consideradas boas fontes de compostos fenólicos totais, sendo que a natureza específica dos diferentes tipos deve ser avaliada em estudos futuros.

  5. Profundal benthic invertebrates in an oligotrophic tropical lake: different strategies for coping with anoxia

    Directory of Open Access Journals (Sweden)

    María del Carmen Hernández

    2014-05-01

    Full Text Available The deep benthic communities of tropical lakes are poorly understood with respect to their composition, abundance, biomass and regulatory factors. Whereas the hypolimnia of temperate oligotrophic lakes remain oxygenated, the higher temperatures in tropical lakes frequently lead to the rapid development of hypolimnetic anoxia independent of trophic status. The deep benthic communities of tropical lakes must therefore develop strategies to respond to anoxic conditions. The dynamics of the deep benthic community of Lake Alchichica were studied over 15 months. We hypothesized that the sedimentation of the winter diatom bloom constitutes an input of high-quality food that contributes to the establishment and development of the deep benthic community. However, the remineralization of this organic matter leads to the prompt development of hypolimnetic anoxia, thus limiting the establishment and/or persistence of the deep benthic community. In contrast with the diverse littoral benthic community (50 taxa in Lake Alchichica, only two species constitute its deep benthic community, the ostracod Candona cf. patzcuaro and the chironomid Chironomus cf. austini, which combined exhibit a low density (1197±1976 ind m-2 and biomass (16.13±30.81 mg C m-2. C. patzcuaro is dominant and is present throughout the year, whereas Ch. austini is recorded only when the bottom water of the lake is oxygenated. A comparison with the analogous but temperate Lake Mergozzo in Italy illustrates the role that anoxia plays in tropical lakes by diminishing not only taxonomic richness (13 versus 2 spp. in temperate versus tropical lakes, respectively but also abundance (1145 versus 287 ind m-2, respectively. C. patzcuaro is found throughout the annual cycle of the lake’s profundal zone, entering into diapause during the anoxic period and recovering as soon as the profundal zone reoxygenates. Ch. austini has adjusted its life cycle to use the habitat and available resources while

  6. Quantifying nitrate dynamics in an oligotrophic lake using Δ17O

    Directory of Open Access Journals (Sweden)

    A. Tanaka

    2011-03-01

    Full Text Available The stable isotopic compositions of nitrate, including the 17O anomalies (Δ17O, were determined twice in 1 yr (June and August 2007 in the oligotrophic water column of Lake Mashu, Japan. These data were then used to quantify the geochemical dynamics of nitrate in the lake, by using the deposition rate of the atmospheric nitrate onto the entire catchment area of the lake. The total amount of nitrate in the lake water decreased from 4.2 to 2.1 Mmol during the period between the observations, while the average Δ17O values remained uniform at +2.5‰. The Δ17O values corresponded to an small and uniform mixing ratio of atmospheric nitrate to total nitrate of 9.7 ± 0.8%. These results indicate that 0.52 ± 0.34 Mmol of the remineralized nitrate was fed into the water column through nitrification, while 2.6 ± 0.4 Mmol of nitrate was simultaneously removed from the water column by assimilation, during the period between the observations. The lake water dissolved nitrate was characterized by rapid removal through assimilation during summer until it was almost completely removed from the euphotic layer, as well as continuous feeding into the lake through nitrification (3.2 ± 0.3 Mmol a−1 and deposition (0.35 ± 0.2 Mmol a−1, regardless of the seasons. The 15N-depleted nitrogen isotopic compositions of nitrate were as low as −6.5‰ in June, which also indicates that in-lake nitrification is the major source of nitrate in the lake and suggests that there is low potential for denitrification in and around the lake. Atmospheric nitrate deposited into the lake will be assimilated quickly, having a mean residence time of 1.2 ± 0.1 yr. In addition, more than 90% of the assimilated nitrate will be remineralized to nitrate and re-assimilated via active nitrogen cycling in the lake.

  7. Plankton origin of particulate dimethylsulfoniopropionate in a Mediterranean oligotrophic coastal and shallow ecosystem

    Science.gov (United States)

    Jean, Natacha; Bogé, Gérard; Jamet, Jean-Louis; Jamet, Dominique; Richard, Simone

    2009-03-01

    We report here dimethylsulfide (DMS) and dimethylsulfoniopropionate (DMSP) levels as a function of plankton communities and abiotic factors over a 12-month cycle in the Mediterranean oligotrophic coastal and shallow ecosystem of Niel Bay (N.W. Mediterranean Sea, France). Total particulate DMSP (DMSP p) and DMS concentrations were highly seasonal, peaking during a spring (April) bloom at 8.9 nM and 73.9 nM, respectively. Significant positive correlations were found between total DMSP p concentration and the abundance or biomass of the dinoflagellate Prorocentrum compressum (Spearman's rank correlation test: r = 0.704; p = 0.011). Similarly, DMS concentrations peaked during the development of blooms of P. compressum and Gymnodinium sp. There seemed to be a positive relationship between the chlorophyll a to pheopigment ratio and DMS concentrations, suggesting that DMS was released during phytoplankton growth. High DMS levels recorded in the shallow Niel Bay may also result from the activity of benthic macroalgae, and/or macrophytes such as Posidonia spp., or the resuspension of sulfur species accumulating in sediments. The fractionation of particulate DMSP into three size classes (>90 μm, 5-90 μm and 0.2-5 μm) revealed that 5-90 μm DMSP-containing particles made the greatest contribution to the total DMSP p pool (annual mean contribution = 62%), with a maximal contribution in April (96%). This size class consisted mainly of dinoflagellates (annual mean contribution = 68%), with P. compressum and Gymnodinium sp. the predominant species, together accounting for up to 44% of the phytoplankton present. The positive correlation between DMSP concentration in the 5-90 μm size class and the abundance of P. compressum (Spearman's rank correlation test: r = 0.648; p = 0.023) suggests that this phytoplankton species would be the major DMSP producer in Niel Bay. The DMSP collected in the >90 μm fraction was principally associated with zooplankton organisms, dominated by

  8. Fens as whole-ecosystem gauges of groundwater recharge under climate change

    Science.gov (United States)

    Drexler, Judith Z.; Knifong, Donna; Tuil, JayLee; Flint, Lorraine E.; Flint, Alan L.

    2013-02-01

    SummaryCurrently, little is known about the impact of climate change on groundwater recharge in the Sierra Nevada and southern Cascade Range of California or other mountainous regions of the world. The purpose of this study was to determine whether small alpine peatlands called fens can be used as whole-ecosystem gauges of groundwater recharge through time. Fens are sustained by groundwater discharge and are highly sensitive to changes in groundwater flow due to hydrologic disturbance including climate change. Seven fens in the Sierra Nevada and southern Cascade Range were studied over a 50-80 year period using historic aerial photography. In each aerial photograph, fen areas were identified as open lawn and partially treed areas that exhibited (1) dark brownish-green coloring or various shades of gray and black in black and white imagery and (2) mottling of colors and clustering of vegetation, which signified a distinct moss canopy with overlying clumped sedge vegetation. In addition to the aerial photography study, a climate analysis for the study sites was carried out using both measured data (U.S. Department of Agriculture Natural Resources Conservation Service SNOwpack TELemetry system) and modeled data (a downscaled version of the Parameter-elevation Regressions on Independent Slopes Model) for the period from 1951 to 2010. Over the study period, the five fens in the Sierra Nevada were found to be decreasing between 10% and 16% in delineated area. The climate analysis revealed significant increases through time in annual mean minimum temperature (Tmin) between 1951-1980 and 1981-2010. In addition, April 1 snow water equivalent and snowpack longevity also decreased between 1951-1980 and 1981-2010. For the fens in the Cascade Range, there were no discernible changes in delineated area. At these sites, increases in Tmin occurred only within the past 20-25 years and decreases in snowpack longevity were more subtle. A conceptual model is presented, which

  9. Fens as whole-ecosystem gauges of groundwater recharge under climate change

    Science.gov (United States)

    Drexler, Judith Z.; Knifong, Donna L.; JayLee Tuil; Flint, Lorraine E.; Flint, Alan L.

    2013-01-01

    Currently, little is known about the impact of climate change on groundwater recharge in the Sierra Nevada and southern Cascade Range of California or other mountainous regions of the world. The purpose of this study was to determine whether small alpine peat lands called fens can be used as whole-ecosystem gauges of groundwater recharge through time. Fens are sustained by groundwater discharge and are highly sensitive to changes in groundwater flow due to hydrologic disturbance including climate change. Seven fens in the Sierra Nevada and southern Cascade Range were studied over a 50-80 year period using historic aerial photography. In each aerial photograph, fen areas were identified as open lawn and partially treed areas that exhibited (1) dark brownish-green coloring or various shades of gray and black in black and white imagery and (2) mottling of colors and clustering of vegetation, which signified a distinct moss canopy with overlying clumped sedge vegetation. In addition to the aerial photography study, a climate analysis for the study sites was carried out using both measured data (U.S. Department of Agriculture Natural Resources Conservation Service SNOwpack TELemetry system) and modeled data (a downscaled version of the Parameter-elevation Regressions on Independent Slopes Model) for the period from 1951 to 2010. Over the study period, the five fens in the Sierra Nevada were found to be decreasing between 10% and 16% in delineated area. The climate analysis revealed significant increases through time in annual mean minimum temperature (Tmin) between 1951-1980 and 1981-2010. In addition, April 1 snow water equivalent and snowpack longevity also decreased between 1951-1980 and 1981-2010. For the fens in the Cascade Range, there were no discernible changes in delineated area. At these sites, increases in Tmin occurred only within the past 20-25 years and decreases in snowpack longevity were more subtle. A conceptual model is presented, which illustrates

  10. Synergistic effects of UVR and simulated stratification on commensalistic algal-bacterial relationship in two optically contrasting oligotrophic Mediterranean lakes

    Science.gov (United States)

    Carrillo, P.; Medina-Sánchez, J. M.; Durán, C.; Herrera, G.; Villafañe, V. E.; Helbling, E. W.

    2014-08-01

    An indirect effect of global warming is the shallowing epilimnion, causing organisms to be exposed to higher levels of ultraviolet (UVR, 280-400 nm) and photosynthetically active radiation (PAR, 400-700 nm), which could affect primary and bacterial production as well as the commensalistic algal-bacterial relationship. The combined effects of UVR and reduction in the depth of the upper mixed layer (UML) were assessed on variables related to the metabolism of algae and bacteria, during in situ experiments performed with natural microplanktonic communities from two oligotrophic lakes with contrasting UVR-transparency (clear vs. opaque) of southern Spain. The negative UVR effects on epilimnetic primary production (PP) and on heterotrophic bacterial production (HBP), intensified by high mean irradiances, were higher in the UVR-opaque than in the UVR-clear lake, and stronger on the algae than on the heterotrophic bacterial communities. Under UVR and high mean irradiance, the algal-bacterial relationship was strengthened in the UVR-clear lake, where excreted organic carbon (EOC) rates exceeded the bacterial carbon demand (BCD). This did not occur in the UVR-opaque lake. The greater UVR damage to algae and bacteria and the weakening of their commensalistic interaction found in the UVR-opaque lake indicates that these ecosystems would be especially vulnerable to stressors related to global change. Thus, our findings may have important implications for the carbon cycle in oligotrophic lakes of the Mediterranean region.

  11. Synergistic effects of UVR and simulated stratification on commensalistic phytoplankton-bacteria relationship in two optically contrasting oligotrophic Mediterranean lakes

    Science.gov (United States)

    Carrillo, P.; Medina-Sánchez, J. M.; Durán, C.; Herrera, G.; Villafañe, V. E.; Helbling, E. W.

    2015-02-01

    An indirect effect of global warming is a reduction in the depth of the upper mixed layer (UML) causing organisms to be exposed to higher levels of ultraviolet (UVR, 280-400 nm) and photosynthetically active radiation (PAR, 400-700 nm). This can affect primary and bacterial production as well as the commensalistic phytoplankton-bacteria relationship. The combined effects of UVR and reduction in the depth of the UML were assessed on variables related to the metabolism of phytoplankton and bacteria, during in situ experiments performed with natural pico- and nanoplankton communities from two oligotrophic lakes with contrasting UVR transparency (high-UVR versus low-UVR waters) of southern Spain. The negative UVR effects on epilimnetic primary production (PP) and on heterotrophic bacterial production (HBP), intensified under increased stratification, were higher in the low-UVR than in the high-UVR lake, and stronger on the phytoplanktonic than on the heterotrophic bacterial communities. Under UVR and increased stratification, the commensalistic phytoplankton-bacteria relationship was strengthened in the high-UVR lake where excretion of organic carbon (EOC) rates exceeded the bacterial carbon demand (BCD; i.e., BCD : EOC(%) ratio 100). The greater UVR damage to phytoplankton and bacteria and the weakening of their commensalistic interaction found in the low-UVR lake indicates that these ecosystems would be especially vulnerable to UVR and increased stratification as stressors related to global climate change. Thus, our findings may have important implications for the carbon cycle in oligotrophic lakes of the Mediterranean region.

  12. Palaeolimnological assessment of environmental change over the last two centuries in oligotrophic Lake Nohipalu Valgjärv, southern Estonia

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    Heinsalu, Atko

    2009-06-01

    Full Text Available The main objectives of this study were to reconstruct the environmental conditions for a small oligotrophic lake during the last two centuries, to determine if the environment of the lake was anthropogenically mediated, and to assess the pre-impact reference conditions with palaeolimnological techniques. A short sediment core from Lake Nohipalu Valgjärv was analysed in detail for diatom assemblages as well as for loss-on-ignition measurements. Accurate chronology of the sediment core was established and evaluated by different independent approaches – 210Pb, 137Cs, and 241Am dating, and the distribution of spheroidal fly-ash particles in sediments. Quantitative inference models based on sedimentary diatoms were applied to reconstruct changes in past lake water pH. Before the mid-19th century, Nohipalu Valgjärv was an oligotrophic lake with clear water continuously transparent down to the bottom and with rich benthic diatom flora. Since the early second half of the 19th century, presumably as a result of forest logging around the lake, water transparency decreased and benthic diatom productivity diminished, and the lake did not recover any more to natural baseline conditions. Due to peat mining activities in the Meenikunno bog, the quality of lake water has changed during the last two decades. The lowered lake level, deteriorated light climate, and decreased pH are the most important environmental variables that have influenced the lake ecosystem.

  13. FEN1 participates in repair of the 5'-phosphotyrosyl terminus of DNA single-strand breaks.

    Science.gov (United States)

    Kametani, Yukiko; Takahata, Chiaki; Narita, Takashi; Tanaka, Kiyoji; Iwai, Shigenori; Kuraoka, Isao

    2016-01-01

    Etoposide is a widely used anticancer drug and a DNA topoisomerase II (Top2) inhibitor. Etoposide produces Top2-attached single-strand breaks (Top2-SSB complex) and double-strand breaks (Top2-DSB complex) that are thought to induce cell death in tumor cells. The Top2-SSB complex is more abundant than the Top2-DSB complex. Human tyrosyl-DNA phosphodiesterase 2 (TDP2) is required for efficient repair of Top2-DSB complexes. However, the identities of the proteins involved in the repair of Top2-SSB complexes are unknown, although yeast genetic data indicate that 5' to 3' structure-specific DNA endonuclease activity is required for alternative repair of Top2 DNA damage. In this study, we purified a flap endonuclease 1 (FEN1) and xeroderma pigmentosum group G protein (XPG) in the 5' to 3' structure-specific DNA endonuclease family and synthesized single-strand break DNA substrates containing a 5'-phoshotyrosyl bond, mimicking the Top2-SSB complex. We found that FEN1 and XPG did not remove the 5'-phoshotyrosyl bond-containing DSB substrates but removed the 5'-phoshotyrosyl bond-containing SSB substrates. Under DNA repair conditions, FEN1 efficiently repaired the 5'-phoshotyrosyl bond-containing SSB substrates in the presence of DNA ligase and DNA polymerase. Therefore, FEN1 may play an important role in the repair of Top2-SSB complexes in etoposide-treated cells. PMID:26581212

  14. Water level fluctuations in rich fens: an assessment of ecological benefits and drawbacks

    NARCIS (Netherlands)

    I.S. Mettrop

    2015-01-01

    For the proper functioning of endangered biodiverse rich fens, base-rich and nutrient-poor (mesotrophic) conditions are required to prevent succession towards Sphagnum-dominated peatlands. Unfortunately, water- and soil quality of many European wetlands are negatively affected by changes in hydrolog

  15. Prospects of fen restoration in relation to changing land use-An example from central Poland

    NARCIS (Netherlands)

    Klimkowska, Agata; Dzierża, Paulina; Grootjans, Ab P.; Kotowski, Wiktor; Diggelen, Rudy Van

    2010-01-01

    We carried out an eco-hydrological analysis to evaluate the most important effects of land use changes on the hydrological functioning of a fen system in Poland. We measured water levels (hydraulic heads) and water flow along a transect through the study area and also analysed land use changes using

  16. Prospects of fen restoration in relation to changing land use—An example from central Poland

    NARCIS (Netherlands)

    Klimkowska, A.; Dzierza, P.; Grootjans, A.P.; Kotowski, W.; Diggelen, R.

    2010-01-01

    We carried out an eco-hydrological analysis to evaluate the most important effects of land use changes on the hydrological functioning of a fen system in Poland. We measured water levels (hydraulic heads) and water flow along a transect through the study area and also analysed land use changes using

  17. The effect of habitat fragmentation and abiotic factors on fen plant occurrence

    NARCIS (Netherlands)

    Soomers, H.; Karssenberg, D.J.; Verhoeven, J.T.A.; Verweij, P.A.; Wassen, M.J.

    2013-01-01

    Human landscape modification has led to habitat fragmentation for many species. Habitat fragmentation, leading to isolation, decrease in patch size and increased edge effect, is observed in fen ecosystems that comprise many endangered plant species. However, until now it has remained unclear whether

  18. O duplo como fenômeno psíquico

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    Marta Regina de Leão D'Agord

    2013-09-01

    Full Text Available Neste trabalho, analisamos um fenômeno psíquico com o qual se ocupa a psicopatologia: o fenômeno do duplo (Doppelgänger, enquanto visão angustiante de si próprio como um outro. Na psicanálise, o duplo pode ser estudado através da concepção do estádio do espelho e do modelo óptico, tais como propostos por Lacan. Entre as elaborações literárias desse fenômeno universal, destacam-se "William Wilson", de E. A. Poe, e "O duplo" de F. Dostoiévski, que se situam no fantástico enquanto gênero literário. Em nossa análise do fenômeno do duplo, realizamos uma comparação entre modelos literários e psicanalíticos.

  19. Effects of root mat buoyancy and heterogeneity on floating fen hydrology

    NARCIS (Netherlands)

    Stofberg, S.F.; Engelen, van Joeri; Witte, J.Ph.M.; Zee, van der S.E.A.T.M.

    2016-01-01

    Floating fen ecosystems are home to several protected habitats and species. Their development and conservation require special
    attention regarding water management. Although they are known to be heterogeneous and partially buoyant, their root mats are
    simulated in hydrological models as homo

  20. Structure and Magnetic Properties of Fe-N Films Prepared by Dual Ion Beam Sputtering

    Institute of Scientific and Technical Information of China (English)

    诸葛兰剑; 吴雪梅; 汤乃云; 叶春兰; 姚伟国

    2001-01-01

    Fe-N films were prepared on Si substrate by dual ion beam sputtering (DIBS). It is of the films were investigated by a vibrating sample magnetometer (VSM). The structure of the films is insensitive to the ratios of N2/Ar in main ion source(MIS), and is mainly influenced by the substrate temperature (Ts).``

  1. Differentiation of fen bedrock in the Ełk Lakeland (NE Poland in relation to late Pleistocene terrain morphogenesis

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    Lemkowska Bożena

    2015-12-01

    Full Text Available The Ełk Lakeland (NE Poland with the area of 263 100 ha was formed during Vistulian glaciation. More than 66% of this region was shaped during the Leszno phase, 15% during the Poznań phase, and 19% during the Pomeranian phase. There are 1854 fens which cover the area of 7.3 % of the Ełk Lakeland mesoregion. Fens have an area of 10.3 ha on average. About 82.5% of the studied fens is located on gyttja deposits, which suggests post-lacustrine origin of the wetlands. Primary the lakes had covered 11% of the Ełk Lakeland, and 6.3% was transformed into fens. Most of them (60% was formed on organic gyttja, 16% on calcareous gyttja, and 6% on clay gyttja. About 17.5% of fens was formed as a result of paludification. The types of bedrock underlying peats differ depending on the phases of glaciation.

  2. Fenóis totais, flavonoides totais e atividade antioxidante de Selaginella convoluta (Arn. Spring (Selaginellaceae

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    Pedro Guilherme Sousa de Sá

    2012-12-01

    Full Text Available Selaginella convoluta é uma espécie conhecida no Nordeste do Brasil como “jericó”, e bastante utilizada na medicina popular para tratamento de doenças. Este estudo teve como objetivo determinar o teor de compostos fenólicos e avaliar a atividade antioxidante in vitro do extrato etanólico e das frações obtidas por partição de S. convoluta. O conteúdo de fenóis totais foi determinado pelo método de Folin-Ciocalteu. O teor de flavonoides totais também foi avaliado. A atividade antioxidante dos extratos foi avaliada usando o método do sequestro do radical DPPH e inibição da auto-oxidação do sistema β-caroteno-ácido linoleico e comparada com os compostos de referência ácido ascórbico, BHA, BHT, quercetina e pirogalol. O conteúdo fenólico total foi de 209,90 ± 19,84 e 61,13 ± 2,50 mg equivalente de ácido gálico/g para os extratos AcOEt e EEB, respectivamente. O conteúdo de flavonoides totais foi de 155,70 ± 6,21 e 62,13 ± 4,10 para os dois extratos, respectivamente. Os extratos AcOEt e EEB apresentaram boas atividades antioxidantes. BHA foi o antioxidante mais efetivo, com um valor de IC50 de 1,62 ± 0,69 µg/mL. Os resultados obtidos mostram que S. convoluta pode ser uma boa fonte de compostos fenólicos antioxidantes. Estudos posteriores serão realizados para se chegar ao isolamento e identificação dos principais constituintes fenólicos dos extratos.

  3. Dissolved organic carbon in a constructed and natural fens in the Athabasca oil sands region, Alberta, Canada.

    Science.gov (United States)

    Khadka, Bhupesh; Munir, Tariq M; Strack, Maria

    2016-07-01

    In the Athabasca oil sands region near Fort McMurray, Alberta, Canada, peatlands are disturbed extensively in order to recover bitumen below the surface. Hence, following oil sands mining, landscape reclamation is a part of the mine closure process in order to return functioning ecosystems, including peatlands, to the region. This study was conducted at a pilot fen reclamation project and three other diverse natural (poor, rich and saline) fens in the oil sands region during the growing seasons of 2013 and 2014, the first and second year post-construction. Ecosystem functioning of the constructed fen (CF) was evaluated with reference to natural fens based on pore water dissolved organic carbon (DOC) concentration and chemistry. Significant variation of DOC concentration among the reference fens was observed, varying from an average of 42.0mg/L at the rich fen (RF) to 70.8mg/L at the saline fen (SF). Dissolved organic carbon concentration at CF was significantly lower than at all reference fens, but increased significantly over the first two years. Seasonal variation of DOC concentration was also observed in each site with concentration increasing over the growing season. At CF, DOC was comprised of larger, more humic and complex aromatic compounds than reference fens in the first year post-construction based on its spectrophotometric properties; however, these differences were reduced in the second year. Initial DOC concentration and chemistry at CF was indicative of the source being largely the peat placed during fen construction. Changes in chemistry and increasing concentration of DOC in the second growing season likely resulted from increasing inputs from plants established on site. These results suggest that DOC concentration is likely to increase in future at CF as vascular plant productivity increases and in response to salinity sourced from tailing sand used to construct the catchment. PMID:27037879

  4. The Comparative Study of Element Accumulation in Wood Fen Peat (Latvia)

    Science.gov (United States)

    Krumins, Janis; Klavins, Maris; Kuske, Eliza; Seglins, Valdis; Kaup, Enn

    2013-04-01

    Mires belong to the most representative archives of past environmental conditions in large areas of temperate and subarctic zone. Moreover, mires keep evidence of ancient cultures and modern human activity. Consequently the research of mires is an integral part of global change studies. Fens are less studied than bogs; one of the reasons is the complexity of factors that impact peat formation. Bogs, due to dome-shaped structure, are affected by precipitation, while other external influences are negligible and simply separable. The aim of this research was the characterization of accumulation patterns of metallic elements in wood fen peat profiles and to assess their accumulation regularities in relation with peat properties. The general idea was to find out how admixtures of plant remains in different stages of decomposition change properties and the element accumulation character in a wood peat. In obtained profiles were separated five types of wood peat: wood, wood-sedge, wood-reed, wood-grass and wood- sphagnum peat. Peat was sampled in four Latvian fens: Elki, Viki, Svetupe and Sala. Similar environment, origin and development of sites suggest similar development of peat properties thus there is no reason to assume different impact on peat development among mires. Despite a slow decomposition rate, results point to a higher decomposition degree of wood peat, in comparison with other types of fen peat. In average, wood peat forms the thickest layers, but it must be taken into account that thickness depends on coating layers, presence of decomposed plant remains etc. The accumulation pattern of metallic elements in a wood fen peat slightly differs among sites, but the difference among wood peat types is clearly evident. For instance, the highest amount of iron is characteristic to wood-reed peat, while, the lowest, is in wood-sphagnum peat. At the same time, in wood-reed peat the lowest amounts of magnesium were found while the highest amount of Mg was in wood

  5. Diverse gene cassettes in class 1 integrons of facultative oligotrophic bacteria of River Mahananda,West Bengal, India.

    Directory of Open Access Journals (Sweden)

    Ranadhir Chakraborty

    Full Text Available BACKGROUND: In this study a large random collection (n=2188 of facultative oligotrophic bacteria, from 90 water samples gathered in three consecutive years (2007-2009 from three different sampling sites of River Mahananda in Siliguri, West Bengal, India, were investigated for the presence of class 1 integrons and sequences of the amplification products. METHODOLOGY/PRINCIPAL FINDINGS: Replica plating method was employed for determining the antibiotic resistance profile of the randomly assorted facultative oligotrophic isolates. Genomic DNA from each isolate was analyzed by PCR for the presence of class 1 integron. Amplicons were cloned and sequenced. Numerical taxonomy and 16S rRNA gene sequence analyses were done to ascertain putative genera of the class 1 integron bearing isolates. Out of 2188 isolates, 1667 (76.19% were antibiotic-resistant comprising of both single-antibiotic resistance (SAR and multiple-antibiotic resistant (MAR, and 521 (23.81% were sensitive to all twelve different antibiotics used in this study. Ninety out of 2188 isolates produced amplicon(s of varying sizes from 0.15 to 3.45 KB. Chi-square (χ(2 test revealed that the possession of class 1 integron in sensitive, SAR and MAR is not equally probable at the 1% level of significance. Diverse antibiotic-resistance gene cassettes, aadA1, aadA2, aadA4, aadA5, dfrA1, dfrA5, dfrA7, dfrA12, dfrA16, dfrA17, dfrA28, dfrA30, dfr-IIe, blaIMP-9, aacA4, Ac-6'-Ib, oxa1, oxa10 and arr2 were detected in 64 isolates. The novel cassettes encoding proteins unrelated to any known antibiotic resistance gene function were identified in 26 isolates. Antibiotic-sensitive isolates have a greater propensity to carry gene cassettes unrelated to known antibiotic-resistance genes. The integron-positive isolates under the class Betaproteobacteria comprised of only two genera, Comamonas and Acidovorax of family Comamonadaceae, while isolates under class Gammaproteobacteria fell under the families

  6. Diversity of cultivated and metabolically active aerobic anoxygenic phototrophic bacteria along an oligotrophic gradient in the Mediterranean Sea

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    C. Jeanthon

    2011-05-01

    Full Text Available Aerobic anoxygenic phototrophic (AAP bacteria play significant roles in the bacterioplankton productivity and biogeochemical cycles of the surface ocean. In this study, we applied both cultivation and mRNA-based molecular methods to explore the diversity of AAP bacteria along an oligotrophic gradient in the Mediterranean Sea in early summer 2008. Colony-forming units obtained on three different agar media were screened for the production of bacteriochlorophyll-a (BChl-a, the light-harvesting pigment of AAP bacteria. BChl-a-containing colonies represented a low part of the cultivable fraction. In total, 52 AAP strains were isolated and the phylogenetic analyses based on their 16S rRNA and pufM genes showed that they were all affiliated to the Alphaproteobacteria. The most frequently isolated strains belonged to Citromicrobium bathyomarinum, and Erythrobacter and Roseovarius species. Most other isolates were related to species not reported to produce BChl-a and/or may represent novel taxa. Direct extraction of RNA from seawater samples enabled the analysis of the expression of pufM, the gene coding for the M subunit of the reaction centre complex of aerobic anoxygenic photosynthesis. Clone libraries of pufM gene transcripts revealed that most phylotypes were highly similar to sequences previously recovered from the Mediterranean Sea and a large majority (~94% was affiliated with the Gammaproteobacteria. The most abundantly detected phylotypes occurred in the western and eastern Mediterranean basins. However, some were exclusively detected in the eastern basin, reflecting the highest diversity of pufM transcripts observed in this ultra-oligotrophic region. To our knowledge, this is the first study to document extensively the diversity of AAP isolates and to unveil the active AAP community in an oligotrophic marine environment. By pointing out the

  7. Diversity of cultivated and metabolically active aerobic anoxygenic phototrophic bacteria along an oligotrophic gradient in the Mediterranean Sea

    Directory of Open Access Journals (Sweden)

    C. Jeanthon

    2011-07-01

    Full Text Available Aerobic anoxygenic phototrophic (AAP bacteria play significant roles in the bacterioplankton productivity and biogeochemical cycles of the surface ocean. In this study, we applied both cultivation and mRNA-based molecular methods to explore the diversity of AAP bacteria along an oligotrophic gradient in the Mediterranean Sea in early summer 2008. Colony-forming units obtained on three different agar media were screened for the production of bacteriochlorophyll-a (BChl-a, the light-harvesting pigment of AAP bacteria. BChl-a-containing colonies represented a low part of the cultivable fraction. In total, 54 AAP strains were isolated and the phylogenetic analyses based on their 16S rRNA and pufM genes showed that they were all affiliated to the Alphaproteobacteria. The most frequently isolated strains belonged to Citromicrobium bathyomarinum, and Erythrobacter and Roseovarius species. Most other isolates were related to species not reported to produce BChl-a and/or may represent novel taxa. Direct extraction of RNA from seawater samples enabled the analysis of the expression of pufM, the gene coding for the M subunit of the reaction centre complex of aerobic anoxygenic photosynthesis. Clone libraries of pufM gene transcripts revealed that most phylotypes were highly similar to sequences previously recovered from the Mediterranean Sea and a large majority (~94 % was affiliated to the Gammaproteobacteria. The most abundantly detected phylotypes occurred in the western and eastern Mediterranean basins. However, some were exclusively detected in the eastern basin, reflecting the highest diversity of pufM transcripts observed in this ultra-oligotrophic region. To our knowledge, this is the first study to document extensively the diversity of AAP isolates and to unveil the active AAP community in an oligotrophic marine environment. By pointing out the discrepancies

  8. Specific growth rate plays a critical role in hydrogen peroxide resistance of the marine oligotrophic ultramicrobacterium Sphingomonas alaskensis strain RB2256

    NARCIS (Netherlands)

    Ostrowski, M; Cavicchioli, R; Gottschal, JC; Blaauw, Maarten

    2001-01-01

    The marine oligotrophic ultramicrobacterium Sphingomonas alaskensis RB2256 has a physiology that is distinctly different from that of typical copiotrophic marine bacteria, such as Vibrio angustum S14. This includes a high level of inherent stress resistance and the absence of starvation-induced stre

  9. Large clean mesocosms and simulated dust deposition: a new methodology to investigate responses of marine oligotrophic ecosystems to atmospheric inputs

    Directory of Open Access Journals (Sweden)

    C. Guieu

    2010-04-01

    Full Text Available Intense Saharan dust deposition occurs over large oligotrophic areas in the Mediterranean Sea and the Tropical Atlantic and its impact on the biogeochemical functioning of such oligotrophic ecosystems needs to be understood. However, due to the logistical difficulties to investigate in-situ natural dust events and due to the inherent limitations of microcosm laboratory experiments, new experimental approaches need to be developed. In this paper, we present a new experimental set up based on large clean mesocoms deployed in the frame of the DUNE (a DUst experiment in a low-Nutrient, low-chlorophyll Ecosystem project. We demonstrate that these tools are highly relevant and provide a powerful new strategy to in situ study the response of an oligotrophic ecosystem to chemical forcing by atmospheric deposition of African dust. First, we describe how to cope with the large amount of dust aerosol needed to conduct the seeding experiments, by producing an analogue from soil collection in a source area and performing subsequent appropriate physico-chemical treatment in the laboratory including an eventual processing by simulated cloud water. The comparison of physico-chemical characteristics of produced dust analogues with the literature confirms that our experimental simulations are representative of dust, ageing during atmospheric transport, and subsequent deposition to the Mediterranean. Second, we demonstrate the feasibility in coastal area to installing in situ, a series of large (6×52 m3 mesocosms without perturbing the local ecosystem. All the setup, containing no metallic part and with as less as possible induced perturbation during the sampling sequence, allows working with the required conditions for biogeochemical studies in oligotrophic environments where nutrient and micronutrients are at nano- or subnano-molar levels. Two distinct "seeding experiments" were conducted by deploying mesocosms in triplicates: three mesocosms serving

  10. The most oligotrophic subtropical zones of the global ocean: similarities and differences in terms of chlorophyll and yellow substance

    Directory of Open Access Journals (Sweden)

    A. Morel

    2010-10-01

    Full Text Available The cores of the subtropical anticyclonic gyres are characterized by their oligotrophic status and minimal chlorophyll concentration, compared to that of the whole ocean. These zones are unambiguously detected by space borne ocean color sensors thanks to their typical spectral reflectance, which is that of extremely clear and deep blue waters. Not only the low chlorophyll (denoted [Chl] level, but also a reduced amount of colored dissolved organic matter (CDOM or "yellow substance" account for this clarity. The oligotrophic waters of the North and South Pacific gyres, the North and South Atlantic gyres, and the South Indian gyre have been comparatively studied with respect to both [Chl] and CDOM contents, by using 10-year data (1998–2007 of the Sea-viewing Wide field-of-view Sensor (SeaWiFS, NASA. Albeit similar these oligotrophic zones are not identical regarding their [Chl] and CDOM contents, as well as their seasonal cycles. According to the zone, the averaged [Chl] value varies from 0.026 to 0.059 mg m−3, whereas the ay(443 average (the absorption coefficient due to CDOM at 443 nm is between 0.0033 and 0.0072 m−1. The CDOM-to-[Chl] relative proportions also differ between the zones. The clearest waters, corresponding to the lowest [Chl] and CDOM concentrations, are found near Easter Island and near Mariana Islands in the western part of the North Pacific Ocean. In spite of its low [Chl], the Sargasso Sea presents the highest CDOM content amongst the six zones studied. Except in the North Pacific gyre (near Mariana and south of Hawaii islands, a conspicuous seasonality appears to be the rule in the other 4 gyres and affects both [Chl] and CDOM; both quantities vary in a ratio of about 2 (maximum-to-minimum. Coinciding [Chl] and CDOM peaks occur just after the local winter solstice, which is also the period of the maximal mixed layer depth in these latitudes. It is hypothesized that the vertical

  11. The most oligotrophic subtropical zones of the global ocean: similarities and differences in terms of chlorophyll and yellow substance

    Directory of Open Access Journals (Sweden)

    A. Morel

    2010-07-01

    Full Text Available The cores of the subtropical anticyclonic gyres are characterized by their oligotrophic status and minimal chlorophyll concentration, compared to that of the whole ocean. These zones are unambiguously detected by space borne ocean color sensors thanks to their typical spectral reflectance, which is that of extremely clear and deep blue waters. Not only the low chlorophyll (denoted [Chl] level, but also a reduced amount of colored dissolved organic matter (CDOM or "yellow substance" account for this clarity. The oligotrophic waters of the North and South Pacific gyres, the North and South Atlantic gyres, and the South Indian gyre have been comparatively studied with respect to both [Chl] and CDOM contents, by using 10-year data (1998–2007 of the Sea-viewing Wide field-of-view Sensor (SeaWiFS, NASA. Albeit similar these oligotrophic zones are not identical regarding their [Chl] and CDOM contents, as well as their seasonal cycles. According to the zone, the averaged [Chl] value varies from 0.026 to 0.059 mg m−3, whereas the ay(443 average (the absorption coefficient due to CDOM at 443 nm is comprised between 0.0033 and 0.0072 m−1. The CDOM-to-[Chl] relative proportions also differ between the zones. The clearest waters, corresponding to the lowest [Chl] and CDOM concentrations, are found near Easter Island and near Mariana Islands in the western part of the North Pacific Ocean. In spite of its low [Chl], the Sargasso Sea presents the highest CDOM content amongst the six zones studied. Except in the North Pacific gyre (near Mariana and south of Hawaii islands, a conspicuous seasonality appears to be the rule in the other 4 gyres and affects both [Chl] and CDOM; both quantities vary in a ratio of about 2 (maximum-to-minimum. Coinciding [Chl] and CDOM peaks occur just after the local winter solstice, which is also the period of the maximal mixed layer depth in these latitudes. It is hypothesized

  12. Theoretical study on the interaction of pristine, defective and strained graphene with Fen and Nin (n = 13, 38, 55) clusters

    Science.gov (United States)

    Song, Wei; Jiao, Menggai; Li, Kai; Wang, Ying; Wu, Zhijian

    2013-11-01

    The structural and electronic properties of Fen and Nin (n = 13, 38, 55) clusters interacting with pristine, defective and strained graphene are investigated by means of self-consistent charge density-functional tight binding (SCC-DFTB) method. The cluster size dependence, defect influence, and strain effect are discussed. We found that the defects play an important role in stabilizing metal clusters by forming metal-carbon σ bonds. Large charge redistribution of Fen compared to Nin lead to stronger interaction in Fen@graphene. The results suggested that tuning the morphological level of the substrate defect and cluster size could affect the catalytic activity of the metal cluster.

  13. Land cover or climate? In search of dominant factors inducing groundwater recharge and fen hydrology in European scale

    Science.gov (United States)

    Grygoruk, Mateusz; Kotowski, Wiktor

    2016-04-01

    Groundwater recharge plays the crucial role in development and stability of fens. It was hypothesized that the mid- and late-Holocene acceleration of fens' development in Europe could have been induced by changes in land cover: decreasing areas of forests resulting from the expanding agriculture have enhanced groundwater recharge by decreasing evapotranspiration and interception and promoting infiltration. However, regardless human-related changes of the landscape, recorded climatic fluctuations could also be considered as drivers of changing groundwater recharge that affects fen stability and development. Nowadays, when up to 90% of European wetlands is considered degraded, assessing vulnerability of groundwater recharge to changing landscape and climate is of the crucial importance for setting fen restoration and management strategies. Main goal of our study was to assess the magnitude of changes in groundwater recharge estimation resulting from modelled changes of the landscape and climatic features in >300 fens located in Poland, Germany, The Netherlands, Sweden, UK and Norway. In our approach we (1) delineated the most probable extents of catchments of particular fens analysed, (2) assumed hypothetical and the most probable changes of land cover within these catchments, (3) assumed the most probable ranges of climatic changes in each of the catchments including historical reconstructions (Holocene) and future projections (A1B scenario, CSIRO:MK3 and UKMO:HADCM3 GCM-RCM ensembles), (4) developed, tested and calibrated automatic, GIS-based groundwater recharge calculation algorithm to be applied in the study, (5) calculated groundwater recharge in multiple probable combinations of landscape and climatic conditions and (6) performed statistical analysis in order to reveal whether the climate or landscape changes were the dominant factors that could have probably influenced groundwater recharge in catchments of fens analysed. We revealed that in the case of 80% of

  14. Efecto antioxidante y antihipertensivo de diferentes compuestos fenólicos del aceite de oliva virgen "in vitro"

    OpenAIRE

    González Gómez-Navarro, Cecilia

    2009-01-01

    Consta de 2 estudios in vitro:1. La valoración de la capacidad antioxidante de 19 compuestos fenólicos del AOV, mediante la Lag Phase de los dienos conjugados de la LDL inducida por Cu2+. Los compuestos fenólicos con mayor actividad antioxidante son, en orden decreciente: luteolina, rutina, hidroxitirosol, oleuropeína y 3,4-DHPEA-EDA. La mezcla de estos 5 compuestos incrementa en 1.8 veces la suma de la Lag Phase de cada uno de los compuestos fenólicos individualmente (p

  15. Dense microbial community on a ferromanganese nodule from the ultra-oligotrophic South Pacific Gyre: Implications for biogeochemical cycles

    Science.gov (United States)

    Shiraishi, Fumito; Mitsunobu, Satoshi; Suzuki, Katsuhiko; Hoshino, Tatsuhiko; Morono, Yuki; Inagaki, Fumio

    2016-08-01

    During Integrated Ocean Drilling Program (IODP) Expedition 329, a deep-sea ferromanganese nodule and surrounding sediment were collected from the South Pacific Gyre, the most oligotrophic oceanic environment on earth. Using a combination of cryo-sectioning and fluorescence-based cell counting techniques, we determined that the microbial cell density at the very surface of the nodule was ∼108 cells cm-3, three orders of magnitude higher than that in the surrounding sediment. Analysis of bacterial and archaeal 16S rRNA gene sequences (∼1400 bp) indicated that the taxonomic composition of the nodule-associated community differed markedly from that of the sediment-associated community. Members of Marine Group I (MGI) Thaumarchaeota are potentially crucial for sustaining the high cell density because both ammonia and Cu were available on the nodule surface, making it suitable for ammonia-oxidizing chemolithoautotrophy mediated by copper enzymes. Combined cryo-sectioning and synchrotron analysis of the nodule surface revealed both hexagonal birnessite resembling δ-MnO2 and triclinic birnessite, minerals characteristic of biogenic oxide and its secondary product, respectively. Regardless of these possible biogenic features, only one gene sequence exhibited some similarity to previously identified manganese-oxidizing bacteria. On the other hand, MGI Thaumarchaeota were assumed as potential candidate of manganese oxidizers because they have multi-copper oxidase that is utilized by most known manganese oxidizers. Therefore, this archaeal group is considered to play a significant ecological role as a primary producer in biogeochemical elemental cycles in the ultra-oligotrophic abyssal plain.

  16. Variable nutrient stoichiometry (carbon:nitrogen:phosphorus) across trophic levels determines community and ecosystem properties in an oligotrophic mangrove system.

    Science.gov (United States)

    Scharler, U M; Ulanowicz, R E; Fogel, M L; Wooller, M J; Jacobson-Meyers, M E; Lovelock, C E; Feller, I C; Frischer, M; Lee, R; McKee, K; Romero, I C; Schmit, J P; Shearer, C

    2015-11-01

    Our study investigated the carbon:nitrogen:phosphorus (C:N:P) stoichiometry of mangrove island of the Mesoamerican Barrier Reef (Twin Cays, Belize). The C:N:P of abiotic and biotic components of this oligotrophic ecosystem was measured and served to build networks of nutrient flows for three distinct mangrove forest zones (tall seaward fringing forest, inland dwarf forests and a transitional zone). Between forest zones, the stoichiometry of primary producers, heterotrophs and abiotic components did not change significantly, but there was a significant difference in C:N:P, and C, N, and P biomass, between the functional groups mangrove trees, other primary producers, heterotrophs, and abiotic components. C:N:P decreased with increasing trophic level. Nutrient recycling in the food webs was highest for P, and high transfer efficiencies between trophic levels of P and N also indicated an overall shortage of these nutrients when compared to C. Heterotrophs were sometimes, but not always, limited by the same nutrient as the primary producers. Mangrove trees and the primary tree consumers were P limited, whereas the invertebrates consuming leaf litter and detritus were N limited. Most compartments were limited by P or N (not by C), and the relative depletion rate of food sources was fastest for P. P transfers thus constituted a bottleneck of nutrient transfer on Twin Cays. This is the first comprehensive ecosystem study of nutrient transfers in a mangrove ecosystem, illustrating some mechanisms (e.g. recycling rates, transfer efficiencies) which oligotrophic systems use in order to build up biomass and food webs spanning various trophic levels. PMID:26183835

  17. Fenómenos que Organizan el Límite (Phenomena that Organize Limits)

    OpenAIRE

    María Teresa Sánchez; Francisco Javier Claros; Moisés Coriat

    2007-01-01

    En este artículo se pone de manifiesto la presencia de los fenómenos de aproximación organizados por una definición de límite en el caso de las sucesiones de números reales y de las funciones reales de una variable real. La exposición incluye la caracterización de tales fenómenos, una descripción del análisis comparativo desarrollado en base a ellos entre dos definiciones formales de límite de sucesión y función, y una síntesis del estudio llevado a cabo sobre una muestra intencional de libro...

  18. Fenómenos que organizan el límite

    OpenAIRE

    Claros, Francisco Javier; Sánchez, María Teresa; Coriat, Moisés

    2006-01-01

    En este artículo se pone de manifiesto la presencia de los fenómenos de aproximación organizados por una definición de límite en el caso de las sucesiones de números reales y de las funciones reales de una variable real. La exposición incluye la caracterización de tales fenómenos, una descripción del análisis comparativo desarrollado en base a ellos entre dos definiciones formales de límite de sucesión y función, y una síntesis del estudio llevado a cabo sobre una muestra intencional de libro...

  19. Effects of magnetic ions on optical properties: the case of (Ga, Fe)N

    Energy Technology Data Exchange (ETDEWEB)

    Wegscheider, M; Li Tian; Navarro-Quezada, A; Faina, B; Bonanni, A [Institute for Semiconductor and Solid State Physics, Johannes Kepler University, Altenbergerstrasse 69, A-4040, Linz (Austria); Pacuski, W [Institute of Experimental Physics, University of Warsaw, Hoza 69, PL-00-681 Warszawa (Poland); Jakiela, R; Dietl, T [Institute of Physics, Polish Academy of Sciences, aleja Lotnikow 32/46, PL 02-668 Warszawa (Poland)], E-mail: alberta.bonanni@jku.at, E-mail: dietl@ifpan.edu.pl

    2008-11-12

    Because of strong exchange interactions between localized spins and effective mass carriers, transition metal impurities in semiconductors lead to giant magneto-optical effects. Furthermore, band-gap levels derived from open d shells of magnetic impurities act as efficient recombination centers for photo-carriers. This paper reviews studies of excitonic magneto-reflectivity performed on (Ga, Fe)N epilayers, and shows how hybridization between d levels and band states, particularly strong in nitrides and oxides, renormalizes the exchange splitting of the valence band states in these systems. Photoluminescence measurements on the same structures demonstrate an increase of infrared Fe-related emission at the expense of ultraviolet near band-gap luminescence. This sensitivity of luminescence to the presence of Fe impurities is exploited to monitor the aggregation of Fe{sub x}N nanocrystals that account for the room temperature ferromagnetism of (Ga, Fe)N, but do not act as inhibitors of excitonic luminescence.

  20. Desempleo entre los jornaleros agrícolas, un fenómeno emergente

    Directory of Open Access Journals (Sweden)

    Antonieta Barrón

    2013-01-01

    Full Text Available Este artículo tiene como propósito presentar un fenómeno no planteado en el estudio de mercados de trabajo agrícolas y empleo rural, se cuestiona la definición de desem- pleo, y se plantea cómo esta definición, asumida por el inegi, se aplica en los mercados de trabajo formales pero no en los no formales, los agrícolas. Se hacen comparaciones entre los niveles nacional y rural para concluir con los estudios de caso que refuerzan la tesis inicial, el aumento del desempleo en los mercados de trabajo rurales. A lo largo del trabajo se resaltan las diferencias por sexo y se conlcuye que el desempleo rural afecta más a las mujeres que los hombres, fenómeno contrario al de nivel nacional.

  1. Formation dynamics of FeN thin films on Cu(100)

    KAUST Repository

    Heryadi, Dodi

    2012-01-01

    To investigate the structural and magnetic properties of thin films of FeN we have performed ab initio molecular dynamics simulations of their formation on Cu(100) substrates. The iron nitride layers exhibit a p4gm(2 × 2) reconstruction and order ferromagnetically in agreement with experiment. We establish the dynamics and time scale of the film formation as a function of the film thickness. The process is split in two phases: formation of almost flat FeN layers and optimization of the distance to the substrate. Our calculated magnetic moments are 1.67 μ B, 2.14 μ B, and 2.21 μ B for one, two, and three monolayers of iron nitride. © 2011 Elsevier B.V. All rights reserved.

  2. Ab initio investigation of the electronic structure and the magnetic trends within equiatomic FeN

    Science.gov (United States)

    Houari, A.; Matar, S. F.; Belkhir, M. A.

    2007-05-01

    The magnetic properties of equiatomic FeN nitride have been investigated within the density functional theory (DFT) using the augmented spherical wave method (ASW). Calculation of the energy versus volume in hypothetic rocksalt (RS), zinc-blende (ZB) and wurtzite (W) types structures show that the RS-type structure is preferred. At equilibrium, energy/volume spin polarized calculations indicate that the ground state of RS-FeN is ferromagnetic with a high moment, while ZB-FeN and W-FeN are non magnetic. The magnetovolume effects with respect to the Slater-Pauling-Friedel model are discussed. Analyses of the electronic structure (density of states and chemical bonding) are reported. A discussion of the structural and magnetic properties of FeN compound is given with respect to N local environment of Fe.

  3. Fe and N diffusion in nitrogen-rich FeN measured using neutron reflectometry

    Indian Academy of Sciences (India)

    Mukul Gupta; A Gupta; A Wildes; T Gutberlet

    2008-11-01

    Grazing incidence neutron reflectometry provides an opportunity to measure the depth profile of a thin film sample with a resolution <1 nm, in a non-destructive way. In this way the diffusion across the interfaces can also be measured. In addition, neutrons have contrast among the isotopes, making it feasible to measure the self-diffusion. In the present work, the isotope multilayers of [FeN/57 FeN]10 and [FeN/Fe15N]10 were prepared using magnetron sputtering and self-diffusion of Fe and N was investigated. It was found that N diffusion is slower compared to Fe and does not follow the atomic size dependence.

  4. Perfil fenólico de um extracto de tomilho limão

    OpenAIRE

    Olívia R. Pereira; Peres, António M.; Domingues, M. R. M.; Cardoso, Susana M.

    2011-01-01

    O tomilho limão é uma espécie do género Thymus cultivada na região mediterrânica e utilizada, desde há várias décadas, no tratamento de diversas afecções respiratórias e como agente antiséptico e antifúngico [1]. Este estudo pretende contribuir para um melhor conhecimento da espécie Thymus citriodorus, através da identificação e quantificação dos seus principais compostos fenólicos. O perfil fenólico do extracto etanólico de Thymus citriodorus foi obtido por análise de cromatografia líquida d...

  5. Phase Transformations and Phase Equilibria in the Fe-N System at Temperatures below 573 K

    DEFF Research Database (Denmark)

    Malinov, S.; Böttger, A.J.; Mittemeijer, E.J.;

    2001-01-01

    The phase transformations of homogeneous Fe-N alloys of nitrogen contents from 10 to 26 at. pct were investigated by means of X-ray diffraction analysis upon aging in the temperature range from 373 to 473 K. It was found that precipitation of alpha double prime-Fe16N2 below 443 K does not only oc...... occur upon aging of supersaturated alpha (ferrite) and alpha prime (martensite), but also upon transformation of gamma prime-Fe4N1-z and epsilon-Fe2N1-x (......The phase transformations of homogeneous Fe-N alloys of nitrogen contents from 10 to 26 at. pct were investigated by means of X-ray diffraction analysis upon aging in the temperature range from 373 to 473 K. It was found that precipitation of alpha double prime-Fe16N2 below 443 K does not only...

  6. Arrangements of Interstitial Atoms in fcc Fe-C and Fe-N Solid Solutions

    International Nuclear Information System (INIS)

    The distribution of C and N atoms in the octahedral interstitial sites of the face-centred-cubic austenite phase of the Fe-C and the Fe-N alloys is controversial. In this work, Moessbauer experiments, the quasichemical approximation, the hard-blocking excluded-sites model, the chemical activity data, electron charge calculations and Monte Carlo simulations have been combined to advance in its understanding. A database is developed, with analyses of Moessbauer spectra using models assuming either ordered or random distributions of the interstitial atoms in the interstices around an Fe atom. The data are compared as a function the fraction of occupied sites, and various striking differences between Fe-N and Fe-C alloys are discussed. The experimental trends are confronted with predictions of combined theoretical approaches.

  7. Methanotrophic and Methanogenic Communities in Swiss Alpine Fens Dominated by Carex rostrata and Eriophorum angustifolium

    OpenAIRE

    Cheema, Simrita; Zeyer, Josef; Henneberger, Ruth

    2015-01-01

    Vascular plants play a key role in controlling CH4 emissions from natural wetlands, because they influence CH4 production, oxidation, and transport to the atmosphere. Here we investigated differences in the abundance and composition of methanotrophic and methanogenic communities in three Swiss alpine fens dominated by different vascular plant species under natural conditions. The sampling locations either were situated at geographically distinct sites with different physicochemical properties...

  8. Modeling thermodynamics of Fe-N phases; characterisation of e-Fe2N1-z

    DEFF Research Database (Denmark)

    Pekelharing, M.I.; Böttger, A.; Somers, Marcel A.J.;

    1999-01-01

    In order to arrive at modeling the thermodynamics of Fe-N phases, including long-range (LRO) and short-range ordering (SRO) of the N atoms, it is important to understand the role of N interstitially dissolved in an Fe-host lattice. The crystal structure of -Fe2N1-z consists of an h.c.p. iron sub...

  9. Short-Term Summer Inundation as a Measure to Counteract Acidification in Rich Fens

    OpenAIRE

    Mettrop, Ivan S.; Cusell, Casper; Annemieke M Kooijman; Lamers, Leon P. M.

    2015-01-01

    In regions with intensive agriculture, water level fluctuation in wetlands has generally become constricted within narrow limits. Water authorities are, however, considering the re-establishment of fluctuating water levels as a management tool in biodiverse, base-rich fens (‘rich fens’). This includes temporary inundation with surface water from ditches, which may play an important role in counteracting acidification in order to conserve and restore biodiversity. Inundation may result in an i...

  10. Ácidos fenólicos en paja de trigo. ¿Son éstos los compuestos fenólicos más importantes en la inhibición del crecimiento de las plantas?

    OpenAIRE

    Fidel René Díaz Serrano; Luis Felipe Ramírez Santoyo; Marcos R. Soto Hernández; Prometeo Sánchez García; Manuel Sandoval Villa; Gabriel Alcántar González; Roberto Quintero Lizaola

    2010-01-01

    Se identificaron los principales ácidos fenólicos presentes en paja de trigo por cromatografía líquida de alta resolución (CLAR), coincidiendo en general con los ácidos fenólicos reportados en la literatura científica como los principales compuestos alelopáticos presentes en la paja de trigo. Las concentraciones de estos ácidos fenólicos, cuantificadas en los extractos metanólicos por CLAR, fueron muy bajas (entre 0.17 % y 3.06 %) en relación con la cuantificación de fenólicos solubles totale...

  11. Reclamation design for a fen wetland on a tailings sand deposit in northern Alberta

    Energy Technology Data Exchange (ETDEWEB)

    Wytrykush, C. [Syncrude Canada Ltd., Edmonton, AB (Canada); McKenna, G.T.; Papini, A.G.; Scordo, E.B. [BGC Engineering Inc., Vancouver, BC (Canada)

    2010-07-01

    This paper discussed the first attempt at designing and constructing a fen wetland and surrounding watershed on a soft tailings deposit in the Athabasca oil sands region. Among the main design components were upland hummocks, vegetated swales, a pond for water storage, a fen wetland, and 2 perched fens. For each component, reclamation prescriptions were developed using methods from Syncrude's regulatory approvals for upland forests, advice from technical experts on wetlands, and results from an analogous wetland research program. Prior to the reclamation, a long-term research program was started to appraise the response of wetland plants to different operation treatments, including placement depth, material type, compaction, and salinity. Operation techniques were developed to glean live in-situ peat material from the top layer of the boreal forest for use in wetland reclamation. Design topography and soil material types were taken into account in developing the prescriptions, which were used to test specific research hypotheses within the instrumented research watershed.

  12. Structural stability and magnetism of FeN from first principles

    Science.gov (United States)

    Houari, A.; Matar, S. F.; Belkhir, M. A.; Nakhl, M.

    2007-02-01

    In the framework of density-functional theory, the structural and magnetic properties of FeN mononitride have been investigated using the all-electron augmented spherical wave method with a generalized gradient approximation functional for treating the effects of exchange and correlation. Calculation of the energy versus volume in hypothetic rocksalt (RS-), zinc-blende (ZB-), and wurtzite (W)-type structures shows that the RS-type structure is more stable than the others. Spin-polarized calculation results at equilibrium volume indicate that the ground state of RS-FeN is ferromagnetic with a high moment, while ZB-FeN and W-FeN are nonmagnetic. The influence of distortions on the stability is taken into account by considering FeN in two different face-centered-tetragonal structures (fcts): fct rocksalt and fct zinc blende. The magnetovolume effects with respect to Slater-Pauling-Friedel model are discussed. The electronic structures analyzed from site- and spin-projected density of states are reported. A discussion of the structural and magnetic properties of FeN is given with respect to N local environment of Fe.

  13. EFFECTS OF TREATMENT TEMPERATURE ON THE MICROSTRUCTURE AND MAGNETIC PROPERTIES OF Fe-N THIN FILMS

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Fe-N thin films were fabricated on both 100Si and NaCl substrates by RF magnetron sputtering under low nitrogen partial pressure. The microstructure and magnetic properties of Fe-N thin films were investigated with the increase of the substrate temperature (Ts) and the annealing temperature (Ta). It is more difficult for nitrogen atoms to enter the Fe lattice under higher Ts above 150℃. The phase evolution is visible at higher Tα above 200℃. The phase transformation of α"-Fe16N2 occurred at 400℃. The change of crystal size with Ta was clearly visible from bright and dark field images.The clear high-resolution electron microscope (HREM) images of 110α, 111γ, 112α, and 200α,phases were observed. The interplanar distances from TEM (transmission electron microscope) and HREM match the calculated values very well. From the results of the vibrating sample magnetometer(VSM), the good magnetic properties of Fe-N films were obtained at 150℃ of Ts and 200℃ of Tα,respectively.

  14. High-frequency behavior of FeN thin films fabricated by using reactive sputtering

    Science.gov (United States)

    Hwang, Tae-Jong; Lee, Joonsik; Kim, Ki Hyeon; Kim, Dong Ho

    2016-08-01

    We used ferromagnetic resonance (FMR) and its relationship with the static magnetic properties to investigate the high-frequency behavior of FeN thin films prepared by using reactive sputtering. The FMR was observed in the frequency range from 2 to 18 GHz in the FeN films fabricated at a proper nitrogen flow rate (NFR). In those FeN thin films, a decrease in the saturation magnetization and a corresponding decrease of the FMR frequency were observed as the NFR was increased during the deposition. The external field dependences of the FMR frequencies fit the Kittel formula well, and the Landé g-factors determined from the fit were found to be very close to the free electron value. The high-field damping parameters were almost insensitive to the NFR. However, the lowfield damping parameters exhibited a high sensitivity to the NFR very similar to the dependence of the hard-axis coercivity on the NFR, suggesting that extrinsic material properties, such as impurities and defect structures, could be important in deciding the low-field damping behavior.

  15. Restoring sedges and mosses into frost heaving iron fens, San Juan Mountains, Colorado

    Directory of Open Access Journals (Sweden)

    R.A. Chimner

    2011-08-01

    Full Text Available Rare iron fens in the San Juan Mountains of Colorado are frequently in poor condition due to mining, roads and ditches, which have left much of the fen completely bare of vegetation. Natural revegetation is slow to occur in the bare areas because of severe frost heave in the cold mountain climate. Therefore, experimental revegetation plots were conducted in a factorial design with mulching and no mulching, crossed with moss diaspores, sedge transplants, and moss and sedge combined. Mulching influenced surface soil temperatures by reducing the midday highs and increasing the night-time lows, which decreased the frequency and amount of frost heave. Peat moisture also modified frost heave, with the greatest frost heaving occurring near 75 % peat moisture content (water table 10–20 cm below the surface and the least when soils were either wetter or drier. Moss survival was dependent on mulch, with no moss surviving in plots without mulch. Mulching also increased sedge transplant survival. In summary, mulching significantly increased the success of vegetation restoration efforts for frost heave areas in mountain fens.

  16. Wastewater contaminant transport and treatment in a nutrient limited ribbed fen

    Science.gov (United States)

    McCarter, C. P. R.; Price, J. S.; Branfireun, B. A.

    2015-12-01

    To minimize the discharge of wastewater contaminants from remote northern communities and mining operations, fen peatlands in sub-arctic regions are used for tertiary wastewater treatment to detain, transform, and remove these contaminants. However, there is a limited understanding of contaminant transport and treatment in fen peatlands, particularly in sub-arctic Canada. To better characterize wastewater contaminant transport and treatment in these systems, approximately 44 m3 day-1 of simulated wastewater, concentrated custom-blend fertilizer (NO3-, PO33-, and SO42-) and Cl- diluted with water, was pumped into a small 0.5 ha sub-arctic ribbed fen continuously for 47 days (July 15th -August 31st 2014). Contaminant concentration of 3 similar ribbed fens varied between 0.0-3.0 mg L-1 over the study period (May - September 2014). An exponential increase in transmissivity (2.4 to 16.8 m2 day-1) as the water table rose (~0.16 m) increased the average linear groundwater velocity (0.5 to 3.4 m day-1) and resulted in rapid SO42- (0.8 m day-1) and Cl- (1.9 m day-1) transport. Notwithstanding the rapid transport of Cl-, diffusion into inactive pores still retarded Cl- transport by a factor of 1.8. Contrary to the rapid transport of SO42- and Cl-, the other contaminants were rapidly removed from the pore water (likely through biological uptake or adsorption) and minimal transport was observed (0.29 and 0.04 m day-1 for PO33- and NO3-, respectively). Northern ribbed fens have a large capacity to detain certain wastewater contaminants (e.g., NO3- and PO33-), yet allow rapid transport of others (e.g., SO42- and Cl-). Thus, these peatlands have the potential to significantly decrease wastewater contamination in northern aquatic environment by both biogeochemical and physical processes but careful management of the hydrology is required to prevent the release of mobile contaminants.

  17. Dynamics of peat accumulation and marl flat formation in a calcareous fen, midwestern United States

    Science.gov (United States)

    Miner, J.J.; Ketterling, D.B.

    2003-01-01

    The age and sequence of peat accumulation were investigated at a calcareous fen in northeastern Illinois, USA. The purpose of this study was to identify the processes that form and sustain marl flats, which are areas of marl or tufa substrate within the fen that contain numerous rare plant species. Geomorphic, stratigraphic, and radiocarbon evidence was used to establish the processes and chronology of peat accumulation and erosion adjacent to each marl flat. The age of the base of the peat deposit varies greatly throughout the fen, ranging from 14,679 calibrated years before present (cal. years BP) to nearly modern, indicating that colonization of the sand and gravel substrate by peat occurred throughout the period from the Late Pleistocene to present. Adjacent to one marl flat, trends in basal peat age and thickness show that peat accumulation has progressed laterally inward from both sides, suggesting that the marl flat has been infilling with peat progressively by accumulation at the margins since at least 5,370 cal. years BP or longer. A second marl flat in the fen is surrounded by older, thick peat of differing ages on either edge and is bounded by fresh scarps, indicating that the marl flat currently is expanding laterally by erosion into the preexisting peat blanket. These two examples suggest a continuously repeating process, where erosion of the accumulated peat blanket forms a marl flat, which is later covered by peat accumulation. Trends in basal peat age elsewhere in the fen suggest that other marl flats may have existed in the past that have been completely infilled with peat. This study suggests that marl flat formation is a natural process that has been occurring for millennia, continuously creating habitat for the rare plant species that occupy marl flats. There is no evidence that the marl flats at this site are indicative of anthropogenic disturbance, so that management options for these areas are limited to maintaining the quality and quantity

  18. Could Poor Fens BE More Sensitive than Bogs to Elevated N Deposition in the Oil Sands Region of Northern Alberta?

    Science.gov (United States)

    Wieder, R. K.; Vile, M. A.; Scott, K. D.

    2015-12-01

    Bogs and fens cover 29% of the 140,000 km2 Oil Sands Administrative Area (OSAA) in northern Alberta, a region characterized by quite low background N deposition (1-2 kg/ha/yr). However, development of the oil sands resource has led to increasing emission of nitrogen oxides, which are then returned to regional ecosystems as elevated atmospheric N deposition. Given the nutrient deficient nature of bogs and poor fens, elevated N deposition from oil sands development could potentially affect peatland ecosystem structure and function. To evaluate the ecosystem-level effects of N deposition, since 2011, we have experimentally applied N to a bog and a poor fen near Mariana Lakes, Alberta, located far enough from the OSAA to be unaffected by oil sands emissions. Treatments include simulated rainfall equivalent to N deposition of 0, 5, 10, 15, 20, and 25 kg/ha/yr, plus control plots receiving no added water (3 replicate plots per site per N treatment). Concentrations of NH4+-N, NO3- N, and DON at the top of the peatland water table did not increase with increasing N deposition, averaging 0.61, 0.09, and 1.07 mg/L, respectively, in the bog, and 0.53, 0.10, and 0.81 mg/L, respectively, in the poor fen. Ericaceous shrub abundance increased with increasing N deposition in both the bog and the poor fen, although plot-scale greenness (hand-held spectral measurement of the Normalized Difference Red Edge (NDRE) index) increased with N deposition in the poor fen, but not in the bog. Segmented regression indicated that in the poor fen, at N deposition above 14-16 kg/ha/yr, total microbial, bacterial, and fungal biomass in the top 5 cm of peat increased with N deposition, with no effect at lower N deposition. No effect of N deposition on microbial, bacterial, or fungal biomass was observed at 5-10 cm in the poor fen, or at either 0-5 or 5-10 cm in the bog. In the poor fen, microbial, bacterial, and fungal biomass increased with NDRE, but the effect was not significant in the bog

  19. Application of protein-phenolic based coating on tomatoes (Lycopersicum esculentum Aplicação de coberturas proteicas e fenólicas em tomates (Lycopersicum esculentum

    Directory of Open Access Journals (Sweden)

    Eliane Pereira Cipolatti

    2012-09-01

    Full Text Available The aim of this study was to investigate the use of protein-phenolic based coating made from fermented rice bran on cherry tomatoes (Lycopersicum esculentum. Tests were performed with glycerol 3% (v/v, glycerol with protein-phenolic rice bran extract (5%, glycerol with protein-phenolic extract after 96 hours of fermentation (5%, and a control (without coating. The coated cherry tomatoes were kept at room temperature for 28 days. Mass loss, pH and acidity, total soluble solids, and carotenoids were determined every 96 hours. The coating made from the biomass extract reduced the carotenoid and acidity levels in the fruits studied by 17 and 21.1%, respectively, compared to the control. The coating proved an efficient barrier to water vapor with mass loss of 57% less than the control suggesting that it can be used as an alternative for vegetable tissue conservation.Este trabalho teve como objetivo estudar a utilização de películas, à base de compostos proteicos e fenólicos provenientes de farelo de arroz fermentado, em tomates (Lycopersicum esculentum. Foram realizados testes com: glicerol 3% (v/v; glicerol com extrato fenólico e proteico do farelo de arroz (5%; glicerol com extrato fenólico e proteico da biomassa gerada em 96 hours (5%, e um controle (sem a película. Os tomates revestidos foram mantidos à temperatura ambiente durante 28 dias, sendo determinados, a cada 96 horas, os seguintes aspectos: a perda de massa, o pH e a acidez, os sólidos solúveis totais e os carotenoides. A película elaborada com os extratos da biomassa reduziu os níveis de carotenoides e acidez dos frutos estudados em 17 e 21,1%, respectivamente, em relação ao controle. A película também foi eficiente como barreira ao vapor de água; assim, com perda de massa 57% inferior à do controle, sugere-se que esta poderá ser utilizada como alternativa para conservação desse tecido vegetal.

  20. CO2 and CH4 exchange from ditch networks in two floodplain fens.

    Science.gov (United States)

    Stanley, Kieran; Heppell, Catherine; Belyea, Lisa; Baird, Andrew

    2014-05-01

    Historically, many peatlands were drained using ditches. These ditches are now often used to control water levels in sites under conservation management, though they can be a significant atmospheric source of both CO2 and CH4. Studies have already been undertaken on ditches in ombrotrophic peatlands (bogs), but little work has been done on C exchanges in drainage ditches in floodplain fens. This study quantified C exchange in drainage ditches at two floodplain fens, Sutton Fen (52°45'N 001°30'E) and Strumpshaw Fen (52°36'N 001°27'E), in The Norfolk Broadlands of England. C exchange was quantified between 19th June 2012 and 2nd September 2013 using floating static chambers. Ecosystem respiration (Reco), net ecosystem exchange (NEE) and CH4 fluxes were measured and a seasonal pattern was observed in all three, with the highest fluxes in late summer. Both sites were sources of CO2 and CH4. The few previous studies of C fluxes from ditches in floodplain fens have suggested flux ranges of 69.6 to 199 mg CO2 m2 h-1 for both Reco and NEE, and 1.2 to 366 mg CH4 m2 h-1 (positive means a flux to the atmosphere). For Reco, NEE and CH4, our values were generally at the higher end of the reported values. Reco ranged from 3.66 to 420.18 mg CO2 m-2 h-1 and 28.35 to 257.07 mg CO2 m-2 h-1 for Sutton and Strumpshaw, respectively. The highest flux was observed in September 2013 at Strumpshaw (506.03 mg CO2 m-2 h-1). NEE ranged from -80.64 to 786.2 mg CO2 m-2 h-1 and -70.72 to 229.75 mg CO2 m-2 h-1 for Sutton and Strumpshaw, respectively. The majority of NEE fluxes were positive (a source), apart from April, June and July 2013, where a small uptake occurred. Sutton had significantly greater CH4 emissions than Strumpshaw, with values ranging from 0.46 to 733.72 and 0.05 to 89.11 mg CH4 m-2 h-1, respectively. This difference may have been related to ditch water SO42- concentrations, which were higher at Strumpshaw (23.11 ± 1.26 mg L-1) than at Sutton (17.78 ± 1.68 mg L-1

  1. Evaluation on the Efficiency of Subsurface Drainage in Chiu-Fen Landslide at Northern Taiwan

    Science.gov (United States)

    Ying, L. Y.; Lin, D. G.

    2015-12-01

    For administrative district, the Chiu-Fen landslide is situated at northern Taiwan and comes within the jurisdiction of Ruei-Fang district, New Taipei City Government. Chiu-Fen village is a famous spot for sightseeing and tourism in Southeast Asia. In the last decade, for economic purpose, a vast area of slope land in Chiu-Fen area was reclaimed into business and commercial districts. However, due to the complicated geological and hydrological conditions, improper reclamation, and lack of appropriate soil and water conservation facilities, large scale landslides are frequently triggered by typhoon rainfall and causes damages to the transportation and residential building in the community. As a consequence, the government initiated a comprehensive field investigations and remediation plans to stabilize the landslide from 1997 and the remediation works were concentrated on subsurface drainages, namely the application of drainage well (a vertical shaft with multi-level horizontal drainage boreholes). To investigate the efficiency of drainage wells on the landslide, the A1-profile in the landslide which covers the drainage wells W2 and W4 was selected for a series of rainfall seepage and slope stability analyses. In addition, a 48-hrs design rainfall with return period of 25, 50 and 100 years based on the local meteorological data bank was adopted for the analyses. The numerical results indicate the factor safety FS of the three potential sliding surfaces within A1-profile are constantly keeping greater than one (FS > 1.0) and without decreasing with the elapsed time during rainfall. This implies that the subsurface drainage works can drain off the infiltrated rainwater from a high intensity and long duration rainfall and preserve the slope stability of landslides from deterioration. Finally, the efficiency of the drainage wells can be evaluated quantitatively in terms of the time-dependent factor of safety and the pore water pressure distribution on several potential

  2. Atmospheric methane sources: Alaskan tundra bogs, an alpine fen, and a subarctic boreal marsh

    OpenAIRE

    Sebacher, Daniel I.; Harriss, Robert C.; Bartlett, Karen B.; Sebacher, Shirley M.; Grice, Shirley S.

    2011-01-01

    Methane (CH4) flux measurements from Alaskan tundra bogs, an alpine fen, and a subarctic boreal marsh were obtained at field sites ranging from Prudhoe Bay on the coast of the Arctic Ocean to the Alaskan Range south of Fairbanks during August 1984. In the tundra, average CH4 emission rates varied from 4.9 mg CH4 m-2 d-1 (moist tundra) to 119 mg CH4 m-2 d-1 (waterlogged tundra). Fluxes averaged 40 mg CH4 m-2 d-1 from wet tussock meadows in the Brooks Range and 289 mg CH4 m-2 d-1 from an alpine...

  3. Fenómenos ligados a la validación en álgebra

    OpenAIRE

    Panizza, Mabel

    2006-01-01

    El presente trabajo se inserta en una investigación sobre razonamiento matemático en el dominio del álgebra. En trabajos anteriores (Panizza, 2001; Panizza & Drouhard, 2002, 2003; Drouhard & Panizza, 2003) mostramos una tipología de generalizaciones espontáneas y diversos fenómenos ligados al control por conversión a distintos registros semióticos. En continuidad con estos trabajos, nos hemos dedicado a precisar aspectos relacionados con la capacidad de los alumnos para reconocer la necesidad...

  4. El fenómeno de crianza y sus efectos en el contexto escolar

    OpenAIRE

    Varela Nájera, Dr. Carlos; Universidad Autónoma de Sinaloa; Urtusuastegui Ibarra, Dr. Manuel Alfonso; Universidad Autónoma de Sinaloa; Santoyo Pereda, Lic. Pilar del Carmen; Universidad Autónoma de Sinaloa

    2014-01-01

    En el presente trabajo de investigación se intenta dar cuenta del vínculo entre el fenómeno de crianza y las dificultades escolares de 10 alumnos de sexto grado en una escuela primaria pública de Culiacán, Sinaloa, México. Tiene como objetivo analizar las condiciones de la crianza que inciden en las dificultades escolares de los estudiantes y que, por su carácter subjetivo, plantean limitantes a la labor educativa.  Para ello se utiliza el enfoque cualitativo y el método de estudio de casos. ...

  5. Compostos fenólicos totais e taninos condensados em frutas nativas do cerrado

    OpenAIRE

    Wesley Silveira Rocha; Renata Miranda Lopes; Dijalma Barbosa da Silva; Roberto Fontes Vieira; Joseane Padilha da Silva; Tânia da Silveira Agostini-Costa

    2011-01-01

    As frutas nativas do cerrado têm despertado ultimamente interesse crescente, devido às suas propriedades nutricionais e funcionais aliadas ao potencial para agregar valor e conservar a biodiversidade deste bioma. Muitos compostos fenólicos apresentam capacidade antioxidante de neutralizar a atividade de radicais livres gerados no organismo, que estão associados a diversas doenças crônico-degenerativas. O objetivo deste trabalho foi avaliar a eficiência de três soluções extratoras (acetona a 7...

  6. Fenómenos físicos de las nanopartículas de oro

    OpenAIRE

    Luna Criado, Carlos; Castañeda Rodríguez, Diana; Rosas Torres, Rafael Alberto; Sánchez Juárez, Blanca Patricia; Mendoza Reséndez, Raquel.

    2013-01-01

    El oro ha sido uno de los materiales más preciados por el hombre desde la antigüedad por sus excelentes propiedades, entre las que destaca su hermoso color y brillo, su maleabilidad y su estabilidad química. En las últimas décadas, el interés por este material se ha incrementado al encontrar que el oro en forma de nanopartículas presenta fenómenos físicos nuevos que incrementan su potencial tecnológico. En esta contribución presentamos una breve descripción de algunos de e...

  7. Compostos fenólicos a partir de subprodutos da indústria florestal

    OpenAIRE

    Santos, Sónia Andreia Oliveira

    2012-01-01

    Em Portugal, as indústrias corticeira e de pasta de papel constituem um importante sector económico, contudo, gerando elevadas quantidades de subprodutos. Estes subprodutos poderiam ser explorados em aplicações de alto valor acrescentado, como fonte de compostos fenólicos, por exemplo, em vez de serem apenas queimados para produção de energia. Estes compostos são conhecidos pelas suas inúmeras propriedades, entre as quais, antioxidante, anti-inflamatória e anti-trombótica. ...

  8. A multiple antibiotic and serum resistant oligotrophic strain, Klebsiella pneumoniae MB45 having novel dfrA30, is sensitive to ZnO QDs

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    Chakrabarti Pinak

    2011-05-01

    Full Text Available Abstract Background The aim of this study was to describe a novel trimethoprim resistance gene cassette, designated dfrA30, within a class 1 integron in a facultatively oligotrophic, multiple antibiotic and human serum resistant test strain, MB45, in a population of oligotrophic bacteria isolated from the river Mahananda; and to test the efficiency of surface bound acetate on zinc oxide quantum dots (ZnO QDs as bactericidal agent on MB45. Methods Diluted Luria broth/Agar (10-3 media was used to cultivate the oligotrophic bacteria from water sample. Multiple antibiotic resistant bacteria were selected by employing replica plate method. A rapid assay was performed to determine the sensitivity/resistance of the test strain to human serum. Variable region of class 1 integron was cloned, sequenced and the expression of gene coding for antibiotic resistance was done in Escherichia coli JM 109. Identity of culture was determined by biochemical phenotyping and 16S rRNA gene sequence analyses. A phylogenetic tree was constructed based on representative trimethoprim resistance-mediating DfrA proteins retrieved from GenBank. Growth kinetic studies for the strain MB45 were performed in presence of varied concentrations of ZnO QDs. Results and conclusions The facultatively oligotrophic strain, MB45, resistant to human serum and ten antibiotics trimethoprim, cotrimoxazole, ampicillin, gentamycin, netilmicin, tobramycin, chloramphenicol, cefotaxime, kanamycin and streptomycin, has been identified as a new strain of Klebsiella pneumoniae. A novel dfr gene, designated as dfrA30, found integrated in class 1 integron was responsible for resistance to trimethoprim in Klebsiella pneumoniae strain MB45. The growth of wild strain MB45 was 100% arrested at 500 mg/L concentration of ZnO QDs. To our knowledge this is the first report on application of ZnO quantum dots to kill multiple antibiotics and serum resistant K. pneumoniae strain.

  9. Multivariate and Phylogenetic Analyses Assessing the Response of Bacterial Mat Communities from an Ancient Oligotrophic Aquatic Ecosystem to Different Scenarios of Long-Term Environmental Disturbance

    OpenAIRE

    Silvia Pajares; Valeria Souza; Luis E. Eguiarte

    2015-01-01

    Understanding the response of bacterial communities to environmental change is extremely important in predicting the effect of biogeochemical modifications in ecosystem functioning. The Cuatro Cienegas Basin is an ancient oasis in the Mexican Chihuahuan desert that hosts a wide diversity of microbial mats and stromatolites that have survived in extremely oligotrophic pools with nearly constant conditions. However, thus far, the response of these unique microbial communities to long-term envir...

  10. Response of benthic opportunistic polychaetes and amphipods index to different perturbations in coastal oligotrophic areas (Canary archipelago, North East Atlantic Ocean)

    OpenAIRE

    Riera, Rodrigo; de-la-Ossa-Carretero, Jose Antonio

    2014-01-01

    Oligotrophic areas harbour low macrofaunal abundance and patchy distribution. In these areas it is necessary to test the reliability of biological indicators, especially those based on taxonomic sufficiency where the level of identification is balanced against the need for ecological information and could affect the efficiency of bioindicators. The BOPA (benthic opportunistic polychaetes and amphipods) index was applied in five coastal areas subjected to different perturbations (aquaculture, ...

  11. An experimental study on the effects of nutrient enrichment on organic carbon persistence in the western Pacific oligotrophic gyre

    Science.gov (United States)

    Liu, J.; Jiao, N.; Tang, K.

    2014-09-01

    Carbon sequestration in the ocean is of great concern with respect to the mitigation of global warming. How to hold the fixed organic carbon in the presence of tremendous numbers of heterotrophic microorganisms in marine environments is the central issue. We previously hypothesized that excessive nutrients would ultimately decrease the storage of organic carbon in marine environments. To test this, a series of in situ nutrient enrichment incubation experiments were conducted at a site (17.59° N, 127.00° E) within the western Pacific oligotrophic gyre. Five treatments were employed: glucose (Glu), algal exudation organic material (EOM), nitrate (N) and phosphate (P), N and P in combination with glucose and a control with no added nutrients. The results showed that the dissolved organic carbon consumption rates and bacterial community specific growth rates were enhanced by inorganic nutrient enrichment treatments during the initial 48 h incubation. At the end of 14 days of incubation, about one-third (average 3.3 μmol C kg-1) more organic carbon was respired in the glucose-enriched incubation with the addition of inorganic nutrients compared to that without. In contrast, when nutrients were limiting, glucose could not be efficiently used by the bacteria and thus it remained in the environment. These results suggest that repletion of inorganic nutrients could facilitate microbial consumption of organic carbon and thus has a significant impact on carbon cycling in the environment.

  12. High abundances of potentially active ammonia-oxidizing bacteria and archaea in oligotrophic, high-altitude lakes of the Sierra Nevada, California, USA.

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    Curtis J Hayden

    Full Text Available Nitrification plays a central role in the nitrogen cycle by determining the oxidation state of nitrogen and its subsequent bioavailability and cycling. However, relatively little is known about the underlying ecology of the microbial communities that carry out nitrification in freshwater ecosystems--and particularly within high-altitude oligotrophic lakes, where nitrogen is frequently a limiting nutrient. We quantified ammonia-oxidizing archaea (AOA and bacteria (AOB in 9 high-altitude lakes (2289-3160 m in the Sierra Nevada, California, USA, in relation to spatial and biogeochemical data. Based on their ammonia monooxygenase (amoA genes, AOB and AOA were frequently detected. AOB were present in 88% of samples and were more abundant than AOA in all samples. Both groups showed >100 fold variation in abundance between different lakes, and were also variable through time within individual lakes. Nutrient concentrations (ammonium, nitrite, nitrate, and phosphate were generally low but also varied across and within lakes, suggestive of active internal nutrient cycling; AOB abundance was significantly correlated with phosphate (r(2 = 0.32, p<0.1, whereas AOA abundance was inversely correlated with lake elevation (r(2 = 0.43, p<0.05. We also measured low rates of ammonia oxidation--indicating that AOB, AOA, or both, may be biogeochemically active in these oligotrophic ecosystems. Our data indicate that dynamic populations of AOB and AOA are found in oligotrophic, high-altitude, freshwater lakes.

  13. Microbial food web dynamics in response to a Saharan dust event: results from a mesocosm study in the oligotrophic Mediterranean Sea

    Science.gov (United States)

    Pulido-Villena, E.; Baudoux, A.-C.; Obernosterer, I.; Landa, M.; Caparros, J.; Catala, P.; Georges, C.; Harmand, J.; Guieu, C.

    2014-10-01

    The significant impact of dust deposition on heterotrophic bacterial dynamics in the surface oligotrophic ocean has recently been evidenced. Considering the central role of bacteria in the microbial loop, it is likely that dust deposition also affects the structure and the functioning of the whole microbial food web. In the frame of the DUNE project, aiming to estimate the impact of dust deposition on the oligotrophic Mediterranean Sea through mesocosm experiments, the main goal of the present paper was to assess how two successive dust deposition events affect the dynamics of the microbial food web. The first dust seeding delivered new P and N to the amended mesocosms and resulted in a pronounced stimulation of bacterial respiration. It also induced pronounced, but transient, changes in the bacterial community composition. No significant effects were observed on the abundances of viruses and heterotrophic nanoflagellates. The second dust seeding also delivered new P and N to the amended mesocosms, but the effect on the microbial food web was very different. Bacterial respiration remained constant and bacterial abundance decreased. Compositional changes following the second seeding were minor compared to the first one. The decrease in bacterial abundance coincided with an increase in virus abundance, resulting in higher virus:bacteria ratios throughout the second seeding period. Our study shows that dust deposition to the surface oligotrophic ocean may involve important modifications of the trophic links among the components of the microbial food web with presumed consequences on C and nutrient cycling.

  14. Fenómenos que Organizan el Límite (Phenomena that Organize Limits

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    María Teresa Sánchez

    2007-03-01

    Full Text Available En este artículo se pone de manifiesto la presencia de los fenómenos de aproximación organizados por una definición de límite en el caso de las sucesiones de números reales y de las funciones reales de una variable real. La exposición incluye la caracterización de tales fenómenos, una descripción del análisis comparativo desarrollado en base a ellos entre dos definiciones formales de límite de sucesión y función, y una síntesis del estudio llevado a cabo sobre una muestra intencional de libros de texto de matemáticas.In this paper we show the presence of the phenomena of approximation organized by a definition of limit in the cases of the successions of real numbers and the real functions of one real variable. The exposition includes the characterization of such phenomena, a description of the comparative analysis, developed using them, between two formal definitions of limit of succession and function, and a synthesis of the study carried out on an intentional sample of mathematics textbooks.

  15. A rainha sensual - uma análise do fenômeno Xuxa

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    Jupy Júnior

    2001-02-01

    Full Text Available

    Este artigo teve como origem a monografia de graduação do curso de Comunicação Social, habilitação jornalismo, da Universidade Federal Fluminense, orientada pelo professor doutor Luís Carlos Lopes,  tendo sido apresentada em abril de 2000. A intenção é criar uma discussão a respeito dos principais mecanismos sociais, econômicos, políticos e comunicacionais que tornam possíveis fenômenos de massa como a apresentadora Xuxa Meneghel. Este trabalho tenciona exibir uma persona midiática brasileira de forte apelo junto ao público por um ponto de vista analítico. Também tenciona levantar alguns aspectos que auxiliem em uma discussão mais profunda a respeito de outros fenômenos, bastante difundidos pela televisão – principalmente -, e de que maneira isto afeta a vida das pessoas e o imaginário coletivo brasileiro.

  16. Gravidez na adolescência: um olhar sobre um fenômeno complexo

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    Ana Cristina Garcia Dias

    2010-04-01

    Full Text Available O presente trabalho apresenta uma revisão seletiva e não sistemática da literatura a respeito do fenômeno da gestação na adolescência. Três eixos temáticos orientam a organização do trabalho: (a Riscos e problemas associados à gestação na adolescência; (b Fatores precursores relacionados à gravidez na adolescência; e (c Fatores sócio-culturais associados ao desejo de ser mãe na adolescência. Entre as conclusões, destaca-se que a gravidez na adolescência é uma experiência que pode ter consequências tanto negativas quanto positivas para os adolescentes. Além disso, o fenômeno evidencia a necessidade de intervenções voltadas à saúde sexual e reprodutiva dos adolescentes.

  17. O fenômeno psicossomático no rastro da letra

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    Roseane Freitas Nicolau

    2012-04-01

    Full Text Available Este artigo reflete uma preocupação clínica relativa à operação analítica junto aos fenômenos psicossomáticos. Fazendo-se um estudo das concepções lacanianas sobre o fenômeno psicossomático, nos detivemos nas proposições sobre a escrita, tomando-a na dimensão da escrita no corpo, a qual é uma dimensão distinta do registro do significante, para discutir a possibilidade de uma leitura nas entrelinhas da letra, na direção do tratamento. A relação entre letra e significante é destacada para pensar a passagem do gozo ao inconsciente, ou seja, do real ao simbólico, no manejo possível do gozo, segundo a lógica da quantificação, esperando que uma escrita do gozo possa operar. A ideia de que a escrita do corpo pressupõe efeito de sujeito, isto possibilita pensar o corpo marcado por cicatrizes, cuja operação é a leitura.

  18. Environmental factors controlling fluxes of dimethyl sulfide in a New Hampshire fen

    Science.gov (United States)

    Demello, William Zamboni; Hines, Mark E.

    1992-01-01

    The major environmental factors controlling fluxes of dimethyl sulfide (DMS) in a Sphagnum-dominated peatland were investigated in a poor fen in New Hampshire. DMS emissions from the surface of the peatland varied greatly over 24 hours and seasonally. Maximum DMS emissions occurred in summer with minima in the late fall. Temperature was the major environmental factor controlling these variabilities. There was also some evidence that the changes in water table height might have contributed to the seasonable variability in DMS emission. The influence of the water table was greater during periods of elevated temperature. DMS and MSH were the most abundant dissolved volatile sulfur compound (VSC) in the surface of the water table. Concentrations of dissolved VSC's varied with time and space throughout the fen. Dissolved MDS, MSH, and OCS in the surface of the water table were supersaturated with respect to their concentrations in the atmosphere suggesting that the peat surface was a source of VSC's in the peatland. VCS in peatlands seemed to be produced primarily by microbial processes in the anoxic surface layers of the peat rich in organic matter and inorganic sulfide. Sphagnum mosses were not a direct source of VSC's. However, they increased transport of DMS from the peat surface to the atmosphere.

  19. Measurement of 54Fe(n,2n)53Fe cross section near threshold

    International Nuclear Information System (INIS)

    A series of experiments were performed at the Princeton Plasma Physics Laboratory to measure the cross section of the 54Fe(n,2n)53Fe reaction near threshold. Measurements were made at 6 different neutron energies and cover the 1 MeV energy range from threshold (13.64 MeV) to 14.64 MeV. The 54Fe(n,2n) cross section was measured relative to the 27Al(n,p)27Mg cross section to an accuracy of a few percent. These accurate cross-section measurements will be useful in calculating damage caused by 14 MeV D-T plasma neutrons in Fe and calculating the production of the long-lived 53Mn nuclei that account for much of the buildup of long-lived radioactivity in steel structures and other ferrous materials used in the construction of fusion reactors. They will also play an important part in a new method for measuring the plasma ion temperature of a D-T plasma

  20. 原子簇FenB2(n=1~6)结构和性质的DFT研究%Density Functional Theory Study on Structures and Properties of Cluster FenB2 (n=1~6)

    Institute of Scientific and Technical Information of China (English)

    方志刚; 胡红智

    2006-01-01

    A hundred of clusters FenB2 (n=1~6) were designed to simulate Fe-B amorphous alloys. Clusters Fen(n=1~6) were also concerned to study the effect on the addition of metalloid element. After the clusters models were computed by density functional theory, the most stable structures of clusters were gained. Their geometric,catalytic and magnetic properties have been analyzed and discussed. From the results, it was found that the geometries of most stable clusters FenB2 (n=1~6) were isosceles triangle, diamond, triangle dipyramid, oblique triangular prism ,triangular prism with one hat, and triangular prism with two hats, respectively. Basing on the bond lengths and electronic properties, the clusters models in the present paper could reflect the local structures of FeB amorphous alloys perfectly to a certain extent. The interactions of bond Fe-B were stronger, and the bonds between metal atoms also took some action to the stability of system in clusters of rich iron content. Basing on the studies of thermodynamics, Fermi level and DOS, cluster Fe4B2 could appear more excellent catalytic properties in ammonia synthesis and nitrogen fixation process among the clusters FenB2 (n=1~6). After the study of average3d population of clusters, the average magnetic moments were gained. The calculated average magnetic moments of clusters FenB2 (n=1~6) were less than the relevant theory calculation results of clusters Fen (n=1~6) and the experimental value of pure metal Fe (5.7~6.0 B.M.), and totally appeared soft magnetism.%本文对上百个FenB2和Fen(n=1~6)原子簇模型进行密度泛函理论计算,用来模拟非晶态合金Fe-B体系的局域结构,并考察类金属元素硼的引入对体系性质的影响.将优化构型的键长和电荷分布与实验数值进行比较,发现本文所使用的原子簇模型在一定程度上可以真实、准确地反映非晶态合金Fe-B体系的局域结构.利用这些构型,我们对其键级、电子、催化以

  1. Primary marine aerosol emissions from the Mediterranean Sea during pre-bloom and oligotrophic conditions: correlations to seawater chlorophyll a from a mesocosm study

    Directory of Open Access Journals (Sweden)

    A. N. Schwier

    2014-10-01

    Full Text Available The effect of ocean acidification and changing water conditions on primary marine aerosol emissions is not well understood on a regional or a global scale. To investigate this effect as well as the indirect effect on aerosol that changing biogeochemical parameters can have, ~52 m3 pelagic mesocosms were deployed for several weeks in the Mediterranean Sea during both winter pre-bloom and summer oligotrophic conditions and were subjected to various levels of CO2 to simulate the conditions foreseen in this region for the coming decades. After seawater sampling, primary bubble-bursting aerosol experiments were performed using a plunging water jet system to test both chemical and physical aerosol parameters. Comparing results obtained during pre-bloom and oligotrophic conditions, we find the same four log-normal modal diameters (18.5, 37.5, 91.5, 260 nm describing the aerosol size distribution during both campaigns, yet pre-bloom conditions significantly increased the number fraction of the second (Aitken mode, with an amplitude correlated to virus-like particles, heterotrophic prokaryotes, TEPs, chlorophyll a and other pigments. Organic fractions determined from κ closure calculations for Dp ~50 nm were much larger during the pre-bloom period (64% than during the oligotrophic period (38%, and the organic fraction increased as the particle size decreased. Combining data from both campaigns together, strong positive correlations were found between the organic fraction of the aerosol and chlorophyll a concentrations, heterotrophic and autotrophic bacteria abundance, and dissolved organic carbon (DOC concentrations. As a consequence of the changes in the organic fraction and the size distributions between pre-bloom and oligotrophic periods, we find that the ratio of cloud condensation nuclei (CCN to condensation nuclei (CN slightly decreased during the pre-bloom period. The enrichment of the seawater samples with microlayer samples did not have any

  2. A maturação fenólica em uvas tintas: comparação de metodologias

    OpenAIRE

    Correia, Pedro Tiago Relvas

    2014-01-01

    A maturação fenólica em uvas tintas é uma importante ferramenta de ajuda na decisão de vindima. Com o presente trabalho pretende-se estudar uma nova metodologia de avaliação de parâmetros relacionados com a maturação fenólica das uvas tintas, em comparação com metodologias mais habituais. Neste contexto a maturação fenólica de uvas foi avaliada através de espectrofotometria de refletância difusa e através dos métodos de bancada e dos métodos baseados em espectrofotometria de infra vermelho...

  3. Structure and magnetic properties of columnar Fe-N thin films deposited by direct current magnetron sputtering

    Institute of Scientific and Technical Information of China (English)

    JIA Hui; WANG Xin; PANG Shao-ping; ZHENG Wei-tao; LONG Bei-hong; LI Bo

    2009-01-01

    Columnar Fe-N thin films with thickness ranging from 30 to 150 nm were deposited by direct current magnetron sputtering using an Ar/N2 gas mixture (V(N2)/V(N2+Ar)=5%) on corning glass substrates. The structure, surface morphology and magnetic properties were investigated using X-ray diffractometry(XRD), scanning electron microscopy, atomic force microscopy, transmission electron microscopy(TEM) and superconducting quantum interference magnetometry. XRD investigation shows that Fe-N films exhibit amorphous-like structures; however, TEM measurements indicate the synthesis of mixture phases of α-Fe+ζ-Fe2N+ε-Fe3N in these films. The magnetic anisotropy and coercivity of Fe-N thin films exhibit strong dependence on the film growth behavior and surface morphology. With increasing the height of Fe-N films with column structures, the coercivity increases from 7.96 kA/m to 22.28 kA/m in the direction parallel to the film surface. In perpendicular direction the coercivity only increases slightly from 39.79 kA/m to 43.77 kA/m. However, the values of anisotropy field increase from 0.79×106 to 1.44×106 A/m, which is mainly attributed to the shape anisotropy of elongated columns due to the fact that the difference of magneto-crystalline anisotropy among these Fe-N films is small. The saturation magnetizations of Fe-N films vary with increasing film thickness from 23.5 to 85.1 A-m2/kg.

  4. Peat characteristics and groundwater geochemistry of calcareous fens in the Minnesota River Basin, U.S.A

    Science.gov (United States)

    Almendinger, J.E.; Leete, J.H.

    1998-01-01

    . Calcareous fens in Minnesota are spring-seepage peatlands with a distinctive flora of rare calciphilic species. Peat characteristics and groundwater geochemistry were determined for six calcareous fens in the Minnesota River Basin to better understand the physical structure and chemical processes associated with stands of rare vegetation. Onset of peat accumulation in three of the fens ranged from about 4,700 to 11,000 14C yrs BP and probably resulted from a combination of climate change and local hydrogeologic conditions. Most peat cores had a carbonate-bearing surface zone with greater than 10% carbonates (average 27%, dry wt basis), an underlying carbonate-depleted zone with 10% or less carbonates (average 4%), and a carbonate-bearing lower zone again with greater than 10% carbonates (average 42%). This carbonate zonation was hypothesized to result from the effect of water-table level on carbonate equilibria: carbonate precipitation occurs when the water table is above a critical level, and carbonate dissolution occurs when the water table is lower. Other processes that changed the major ion concentrations in upwelling groundwater include dilution by rain water, sulfate reduction or sulfide oxidation, and ion adsorption or exchange. Geochemical modeling indicated that average shallow water in the calcareous fens during the study period was groundwater mixed with about 6 to 13% rain water. Carbonate precipitation in the surface zone of calcareous fens could be decreased by a number of human activities, especially those that lower the water table. Such changes in shallow water geochemistry could alter the growing conditions that apparently sustain rare fen vegetation.

  5. The response of soil organic carbon of a rich fen peatland in interior Alaska to projected climate change

    Science.gov (United States)

    Fan, Zhaosheng; McGuire, Anthony David; Turetsky, Merritt R.; Harden, Jennifer W.; Waddington, James Michael; Kane, Evan S.

    2013-01-01

    It is important to understand the fate of carbon in boreal peatland soils in response to climate change because a substantial change in release of this carbon as CO2 and CH4 could influence the climate system. The goal of this research was to synthesize the results of a field water table manipulation experiment conducted in a boreal rich fen into a process-based model to understand how soil organic carbon (SOC) of the rich fen might respond to projected climate change. This model, the peatland version of the dynamic organic soil Terrestrial Ecosystem Model (peatland DOS-TEM), was calibrated with data collected during 2005–2011 from the control treatment of a boreal rich fen in the Alaska Peatland Experiment (APEX). The performance of the model was validated with the experimental data measured from the raised and lowered water-table treatments of APEX during the same period. The model was then applied to simulate future SOC dynamics of the rich fen control site under various CO2 emission scenarios. The results across these emissions scenarios suggest that the rate of SOC sequestration in the rich fen will increase between year 2012 and 2061 because the effects of warming increase heterotrophic respiration less than they increase carbon inputs via production. However, after 2061, the rate of SOC sequestration will be weakened and, as a result, the rich fen will likely become a carbon source to the atmosphere between 2062 and 2099. During this period, the effects of projected warming increase respiration so that it is greater than carbon inputs via production. Although changes in precipitation alone had relatively little effect on the dynamics of SOC, changes in precipitation did interact with warming to influence SOC dynamics for some climate scenarios.

  6. Minor long-term effects of ultraviolet-B radiation on methane dynamics of a subarctic fen in Northern Finland

    DEFF Research Database (Denmark)

    Mörsky, Sami K.; Haapala, Jaana K.; Rinnan, Riikka;

    2012-01-01

    The effects of elevated ultraviolet-B (UVB) radiation on methane dynamics was studied in a natural fen in Northern Finland for three growing seasons (2003–2005). This is the first in situ study on the effects of elevated UV-B radiation on methane dynamics in a natural fen. The experimental setup....... The results emphasize the need for long-term field studies under moderately enhanced exposures to estimate whether the function and feedbacks of mire ecosystems change under increased UV-B radiation....

  7. Growth kinetics of thin oxide layers; oxidation of Fe and Fe-N phases at room temperature

    OpenAIRE

    Kooi, Bart J.; Somers, Marcel A. J.; Mittemeijer, Eric J.

    1996-01-01

    The evolution of iron-oxide layers at room temperature on pure polycrystalline α-Fe and on the Fe-N phases γ-Fe[N], γ'-Fe4N1-x and ε-Fe2N1-z was followed in situ with Auger-Electron Spectroscopy. The observed oxidation kinetics of the Fe and Fe-N phases were interpreted using a model considering coupled fluxes of cations and (tunnelling) electrons and an electrostatic potential difference over the oxide layer changing during oxidation. It was concluded that the oxidation kinetics are largely ...

  8. Effects of increasing temperatures on methane concentrations and methanogenesis during experimental incubation of sediments from oligotrophic and mesotrophic lakes

    Science.gov (United States)

    Fuchs, Andrea; Lyautey, Emilie; Montuelle, Bernard; Casper, Peter

    2016-05-01

    Global warming is expected to raise temperatures in freshwater lakes, which have been acknowledged to contribute up to 10% of the atmospheric methane concentrations. Increasing temperature enhances methane production and oxidation rates, but few studies have considered the balance between both processes at experimentally higher temperatures within lake sediments. The temperature dependence of methane concentrations, methane production rates, and methanogenic (mcrA) and methanotrophic (pmoA) community size was investigated in intact sediment cores incubated with aerobic hypolimnion water at 4, 8, and 12°C over 3 weeks. Sediment cores of 25 cm length were collected at two temperate lakes—Lake Stechlin (Germany; mesotrophic-oligotrophic, maximum depth 69.5 m) and Lake Geneva (France/Switzerland; mesotrophic, maximum depth 310 m). While methane production rates in Lake Stechlin sediments did not change with increasing temperatures, methane concentrations decreased significantly. In contrast, methane production rates increased in 20-25 cm in Lake Geneva sediments with increasing temperatures, but methane concentrations did not differ. Real-time PCR demonstrated the methanogenic and methanotrophic community size remained stable independently of the incubation temperature. Methane concentrations as well as community sizes were 1-2 orders of magnitude higher in Lake Stechlin than in Lake Geneva, while potential methane production rates after 24 h were similar in both lakes, with on average 2.5 and 1.9 nmol g-1 DW h-1, respectively. Our results suggest that at higher temperatures methane oxidation could balance, and even exceed, methane production. This suggests that anaerobic methane oxidation could be involved in the methane balance at a more important rate than previously anticipated.

  9. An experimental study on the effects of nutrient enrichment on organic carbon storage in western Pacific oligotrophic gyre

    Directory of Open Access Journals (Sweden)

    J. Liu

    2014-02-01

    Full Text Available Carbon sequestration in the ocean is of great concern with respect to the mitigation of global warming. How to hold the fixed organic carbon in the presence of tremendous heterotrophic microorganisms in marine environments is the central issue. We have previously hypothesized that excessive nutrients would ultimately decrease the storage of organic carbon in marine environments. To test it out, a series of in situ nutrient enrichment incubation experiments were conducted at a site (17.59° N, 127.00° E within the Western Pacific oligotrophic gyre. Five treatments were employed: glucose or algal exudation organic material (EOM and nitrate and phosphate were added alone or in combination to approximate final concentrations of 10 μmol C kg−1, 1 μmol N kg−1 and 0.11 μmol P kg−1 respectively. The results showed that the dissolved organic carbon (DOC consumption rates and bacterial community specific growth rates were enhanced by inorganic nutrients enrichment treatments during the initial 48 h incubation. At the end of 14 days incubation, about 1/3 (average 3.29 μmol C kg−1 more organic carbon was respired from the glucose enriched incubation with addition of inorganic nutrients compared to that without addition of inorganic nutrients. In the case no essential nutrients were available, even glucose could not be efficiently used by bacteria and thus remained in the environment. These results suggest that repletion of inorganic nutrients has negative impacts on carbon preservation, presumably due to elevated nutrient-stimulated bacterial metabolism and respiration, which is meaningful for potential coastal water management and worth for further studies.

  10. An experimental study on the effects of nutrient enrichment on organic carbon storage in western Pacific oligotrophic gyre

    Science.gov (United States)

    Liu, J.; Jiao, N.; Tang, K.

    2014-02-01

    Carbon sequestration in the ocean is of great concern with respect to the mitigation of global warming. How to hold the fixed organic carbon in the presence of tremendous heterotrophic microorganisms in marine environments is the central issue. We have previously hypothesized that excessive nutrients would ultimately decrease the storage of organic carbon in marine environments. To test it out, a series of in situ nutrient enrichment incubation experiments were conducted at a site (17.59° N, 127.00° E) within the Western Pacific oligotrophic gyre. Five treatments were employed: glucose or algal exudation organic material (EOM) and nitrate and phosphate were added alone or in combination to approximate final concentrations of 10 μmol C kg-1, 1 μmol N kg-1 and 0.11 μmol P kg-1 respectively. The results showed that the dissolved organic carbon (DOC) consumption rates and bacterial community specific growth rates were enhanced by inorganic nutrients enrichment treatments during the initial 48 h incubation. At the end of 14 days incubation, about 1/3 (average 3.29 μmol C kg-1) more organic carbon was respired from the glucose enriched incubation with addition of inorganic nutrients compared to that without addition of inorganic nutrients. In the case no essential nutrients were available, even glucose could not be efficiently used by bacteria and thus remained in the environment. These results suggest that repletion of inorganic nutrients has negative impacts on carbon preservation, presumably due to elevated nutrient-stimulated bacterial metabolism and respiration, which is meaningful for potential coastal water management and worth for further studies.

  11. Sources and sinks of nitrogen and phosphorus to a deep, oligotrophic lake, Lake Crescent, Olympic National Park, Washington

    Science.gov (United States)

    Moran, P.W.; Cox, S.E.; Embrey, S.S.; Huffman, R.L.; Olsen, T.D.; Fradkin, S.C.

    2012-01-01

    Lake Crescent, in Olympic National Park in the northwest corner of Washington State is a deep-water lake renowned for its pristine water quality and oligotrophic nature. To examine the major sources and sinks of nutrients (as total nitrogen, total phosphorus, and dissolved nitrate), a study was conducted in the Lake Crescent watershed. The study involved measuring five major inflow streams, the Lyre River as the major outflow, recording weather and climatic data, coring lake bed sediment, and analyzing nutrient chemistry in several relevant media over 14 months. Water samples for total nitrogen, total phosphorous, and dissolved nitrate from the five inflow streams, the outlet Lyre River, and two stations in the lake were collected monthly from May 2006 through May 2007. Periodic samples of shallow water from temporary sampling wells were collected at numerous locations around the lake. Concentrations of nutrients detected in Lake Crescent and tributaries were then applied to the water budget estimates to arrive at monthly and annual loads from various environmental components within the watershed. Other sources, such as leaf litter, pollen, or automobile exhaust were estimated from annual values obtained from various literature sources. This information then was used to construct a nutrient budget for total nitrogen and total phosphorus. The nitrogen budget generally highlights vehicle traffic-diesel trucks in particular-along U.S. Highway 101 as a potential major anthropogenic source of nitrogen compounds in the lake. In contrast, contribution of nitrogen compounds from onsite septic systems appears to be relatively minor related to the other sources identified.

  12. Fenômenos de transporte em sistemas gasosos quaternários reativos

    OpenAIRE

    Silva, Adriano Willian da

    2005-01-01

    Resumo: Este trabalho tem como finalidade apresentar uma análise sobre os efeitos que as reações químicas provocam nos fenômenos de transporte - como por exemplo de massa, momento linear e de energia - em sistemas gasosos quaternários. Para realizar esta análise as reações químicas foram consideradas como sendo processos rápidos, isto _e, processos cuja frequência das interações que resultam em reações químicas possui a mesma ordem de grandeza que a frequência das interações elásticas entre o...

  13. El fenómeno de la "edicionalización" y la prensa local

    Directory of Open Access Journals (Sweden)

    Dra. Antonia González Borjas

    2000-01-01

    Full Text Available El auge experimentado por la prensa local en los últimos años tiene como correlato el interés empresarial de los mass media por satisfacer demandas limitadas a zonas determinadas. Como consecuencia de ello, el periódico local se ha visto acompañado del fenómeno de la "edicionalización", proceso mediante el cual los medios de difusión nacional o regional han logrado un nuevo producto informativo para ciudades distintas con tan sólo cambiar parte de su paginación. Esta dialéctica lleva consigo un doble comportamiento mediático: el rol de contención por parte de las publicaciones locales, mientras que la prensa de ámbito mayor desarrolla el expansionismo informativo.

  14. El fenómeno del dopaje desde la perspectiva de las Ciencias Sociales Odile

    OpenAIRE

    Pardo García, Rodrigo; Gonzalez Aja, Teresa Maria; Irureta-Goyena Sánchez, Pilar; Belloni, Eleonora; Zanibelli, Giacomo; Bogunia-Borowska, Małgorzata; Dabrowski, Adam; Carlos COBO CORRALES; Doudou, Dimi Théodore; Angbo-Effie, Odile; Dibi, Trah Daniel; Kra Konan, Gérard Landy; Koffi, Konan Sosthène; Garcia, Carlos; García Arjona, Noemi

    2015-01-01

    En este libro se recoge una selección de las comunicaciones presentadas en el IV Congreso Internacional ‘Deporte, Dopaje y Sociedad’ que se celebró en Madrid del 26 de febrero al 1 de marzo de 2014 y que fue organizado conjuntamente por la Universidad Politécnica de Madrid y la Agencia Española de Protección de la Salud en el Deporte. Los textos están escritos en español, francés e inglés y abordan el estudio del fenómeno del dopaje desde el ámbito especifico de las Ciencias Humanas y Sociale...

  15. Climate change effects on lowland stream flood regimes and riparian rich fen vegetation communities in Denmark

    DEFF Research Database (Denmark)

    Thodsen, Hans; Baattrup-Pedersen, Annette; Andersen, Hans Estrup;

    2016-01-01

    There is growing awareness that an intensification of the hydrological cycle associated with climate change in many parts of the world will have profound implications for river ecosystem structure and functions. In the present study we link an ensemble of regional climate model projections...... to a hydrological model with the aim to predict climate driven changes in flooding regimes in lowland riparian areas. Our specific aims were to 1) predict effects of climate change on flood frequencies and magnitudes in riparian areas by using an ensemble of six climate models and 2) combine the obtained...... predictions with the distribution of rich fen communities to explore whether these are likely to be subjected to increased flooding by a climate change induced increase in river runoff. We found that all regional climate models in the ensemble showed increases in mean annual runoff and that the increase...

  16. Módulo expositivo e interactivo sobre fenómenos ópticos

    OpenAIRE

    Dionísio, Rogério

    2009-01-01

    As experiências interactivas são um veículo atractivo de disseminação do conhecimento, em particular no domínio da óptica e das suas aplicações. Este artigo descreve um módulo expositivo e interactivo, destinado a explicar os fenómenos físicos relacionados com a luz. O sistema assemelha-se a uma máquina de jogos, que tem no topo um conjunto de seis experiências e vem equipado com um sistema com informação visual e auditiva. Permite ao utilizador escolher qual a experiência que irá ...

  17. Fenômenos sociais, familiares e psicopatológicos associados ao bullying escolar

    OpenAIRE

    Pereira, Beatriz Oliveira; Lourenço, Lélio Moura; Vieira, Marcel; Senra, Luciana Xavier; Gomes, Daniel; Stephan, Francesca

    2012-01-01

    A violência e a violência familiar, assim como transtornos de ansiedade como a fobia/ansiedade social tem sido apontados como fenômenos que possuem algum tipo de associação seja pela semelhança nas características de manifestação, seja pelo impacto provocado nos âmbitos sociais e de saúde dos indivíduos envolvidos. No que concerne a violência e a violência familiar, vale salientar que os atos de omissão e negligência em detrimento do desenvolvimento pleno e da integridade física e psicológ...

  18. Fenómenos solares que afectan la atmósfera terrestre

    Science.gov (United States)

    Rovira, M.

    Se describen los principales fenómenos solares como fulguraciones, prominencias eruptivas, viento solar y eyecciones de masa coronal (CME) que tienen consecuencias en la atmósfera terrestre. En algunos casos el material es eyectado a velocidades superiores a los 900 km/seg y tarda menos de 48 horas en llegar a la Tierra. En general, estos CME no son peligrosos ya que el campo magnético terrestre actúa como protector siendo un aislante efectivo. Si el viento solar es muy intenso puede comprimir la magnetósfera y producir una tormenta geomagnética. En casos extremos, puede interferir la transmisión de potencia eléctrica, perturbar los satélites y producir auroras polares.

  19. Effects of peat-winning on the water environment at a sedge fen ecosystem

    International Nuclear Information System (INIS)

    Peatlands are used in agriculture and forestry for vegetational growth and in peat-winning for soil improvement, horticulture production and as fuel. A prerequisite in peatland use is drainage, with influences on water conditions in the peatland and its surroundings. Environmental effects from such peatland use have been investigated at a sedge fen in central Sweden. Groundwater, runoff, water chemistry and stream water biology were studied during almost 14 years. This period started with a virgin undrained peatland, later being drained for forest production and after a period of seven years intensively drained for peat-winning and with peat harvesting going on for another seven years period with hydrological investigations. Results show a lowered groundwater level, increased runoff and both higher concentrations of most elements and higher leaching from the drained peatland. Biomass and number of individuals of the benthic fauna in stream water also increased. 7 refs, 7 figs, 2 tabs

  20. Effects of peat-winning on the water environment at a sedge fen ecosystem

    International Nuclear Information System (INIS)

    Peatlands are used in agriculture and forestry for vegetational growth and in peat-winning for soil improvement, horticulture production and as fuel. A prerequisite in peatland use is drainage, with influences on water conditions in the peatland and in its surroundings. Environmental effects from such peatland use have been investigated at a sedge fen in central Sweden. Groundwater, runoff, water chemistry and streamwater biology were studied during almost 14 years. This period started with a virgin undrained peatland, later being drained for forest production and after a period of seven years intensively drained for peat-winning and with peat harvesting going on for another seven year period with hydrological investigations. Results show a lowered groundwater level, increased runoff and both higher concentrations of most elements and higher leaching from the drained peatland. Biomass and number of individuals of the benthic fauna in streamwater also increased. 7 refs

  1. The Wonderful World of Wetlands (WWW): Bogs, fens, marshes and swamps and their global environmental significance

    Science.gov (United States)

    Shotyk, W.

    2012-04-01

    Bogs, fens, marshes, and swamps are waterlogged ecosystems where organic soils form and peat accumulates. These are remarkably diverse ecosystems and represent an important component of the biodiversity found on Earth. Their geochemical function is dominated by their predominately anoxic condition which has some important consequences. Best known as reservoirs and reactors for a significant part of our surface freshwater resources, and impacting their chemical composition in remarkable ways, they also have a significant influence on the atmosphere, removing CO2 and adding CH4. The contemporary view during the past centuries was that these were wastelands in need of improving by drainage. Today, however, in some circles at least, the remaining wetlands are valued ecosystems, and the soils they contain archives of climate change, human history and atmospheric pollution.

  2. Innovative wetland reclamation design case studies : the Suncor fen and pond 1 marsh

    Energy Technology Data Exchange (ETDEWEB)

    Daly, C.A. [Suncor Energy, Fort McMurray, AB (Canada); Price, J.; Rezanezhad, F. [Waterloo Univ., ON (Canada); Rochefort, L.; Graf, M. [Laval Univ., Quebec City, PQ (Canada); Russell, B. [BGC Engineering Inc., Calgary, AB (Canada)

    2010-07-01

    Suncor Energy Inc. is an energy company strategically focused in Canada's Athabasca oil sands region. The company has more than 40 years of experience in pioneering commercial development. This presentation discussed reclamation requirements for Suncor Energy. Reclamation objectives that were addressed in this presentation included operating approvals, biodiversity and meeting stakeholder expectations. Several photographs of reclaimed forest areas were shown along with 5 freshwater wetland types and wetland values. Two innovative wetland reclamation design case studies were also presented, described and illustrated, with particular reference to the Suncor fen and pond 1 marsh. It was concluded that future work will involve finalizing site investigation and designs, as well as construction, vegetation, and monitoring. figs.

  3. Efectos ecológicos del fenómeno ENOS en Colombia

    OpenAIRE

    Yesid Carvajal; Henry Jiménez; Hernán Materón

    2014-01-01

    El fenómeno ENOS, tiene un sustancial efecto sobre las variaciones del clima a nivel mundial; por lo tanto, no sorprende que sus efectos tengan un impacto ecológico y socioeconómico fuerte, alterando la seguridad alimentaria de los países a nivel mundial. Ante este panorama, es comprensible que haya despertado el mayor interés mundial, no sólo en los especialistas en meteorología y oceanografía sino también entre biólogos, ecólogos, físicos, matemáticos, agrónomos, hidrólogos, economistas, so...

  4. Partitioning of habitat effects casts light on the decline of the fen orchid, Liparis loeselii

    DEFF Research Database (Denmark)

    Andersen, Dagmar Kappel; Ejrnæs, Rasmus; Minter, Martine Olesen;

    2015-01-01

    Liparis loeselii is a rare and declining orchid species restricted to rich fens in the northern hemisphere. Suggested reasons for the decline are habitat destruction, eutrophication, altered hydrology and scrub encroachment after termination of traditional management such as grazing and hay making....... However, which parameters are most important is not well understood. We use data on vegetation and environmental parameters from extant, potential and historical L. loeselii habitats in Denmark to i) identify a relevant spatial scale for studying L. loeselii; 0.01 m2, 0.25 m2 and 78.5 m2 was tested, ii......) develop a habitat suitability model based on either Ellenberg indicator values or directly measured variables such as tissue nutrient concentrations and vegetation height, and iii) identify the primary reasons for the species decline. We found the largest spatial scale, 78.5 m2 to be superior...

  5. Lignina em espumas fenólicas Lignin in phenolic foams 66

    OpenAIRE

    Gil de Carvalho; Elisabete Frollini

    1999-01-01

    A lignina extraída do bagaço de cana de açúcar pode substituir parcialmente o fenol na preparação de resinas fenólicas. Este trabalho aborda a aplicação de pré-polímero resólico, sendo que o fenol foi parcialmente substituído por lignina (25%, massa lignina/massa fenol ), visando a obtenção de material com características de plástico celular. No presente trabalho descreve-se a caracterização das espumas obtidas por microscopia eletrônica de varredura, conteúdo de células fechadas, densidade a...

  6. Análisis del fenómeno de la violencia contra los ancianos

    Directory of Open Access Journals (Sweden)

    Celín Pérez Nájera

    2010-12-01

    Full Text Available El artículo presenta una revisión bibliográfica sobre el impacto social de la violencia contra los ancianos, desde la óptica criminológica. En el trabajo se utilizó como método investigativo el enfoque dialéctico-materialista de la realidad, que facilitó el engranaje de toda la investigación en diferentes etapas. Las valoraciones generalizadoras y sistematizadoras se elaboraron desde los enfoques modelativo y sistémico-estructural. Luego de analizar la diversidad de conceptos de violencia, se estableció una definición desde una formación social e histórica; existen dos principios que distinguen sus características: uno que la concibe como un fenómeno de carácter social y el teórico-ecológico, que consiste en el empleo de la fuerza física, económica o política, e implica el abuso de poder cómo único método para resolver el conflicto. Así mismo, se examinó el comportamiento de la violencia contra los ancianos en diversos países: España, Estados Unidos, Perú, Brasil, Panamá, Argentina, Colombia, Chile y Cuba. En general, son alarmantes las cifras de incidencia del fenómeno. De igual forma, en Cuba crece la victimización sobre los ancianos. Se aprecia como manifestación fundamental la violencia psicológica o emocional. Aunque existen mecanismos de denuncia, falta de divulgación y sistematicidad de acciones, que permitan enfrentar la incidencia de este mal social, que afecta a dicho grupo de riesgo de la violencia.

  7. CO2 exchange of a temperate fen during the conversion from moderately rewetting to flooding

    Science.gov (United States)

    Koebsch, Franziska; Glatzel, Stephan; Hofmann, Joachim; Forbrich, Inke; Jurasinski, Gerald

    2013-06-01

    Year-round flooding provides a common land management practice to reestablish the natural carbon dioxide (CO2) sink function of drained peatlands. Here we present eddy covariance measurements of net CO2 exchange from a temperate fen during three consecutive growing seasons (May-October) that span a period of conversion from moderately rewetting to flooding. When we started our measurements in 2009, the hydrological conditions were representative for the preceding 20 years with a mean growing season water level (MWGL) of 0 cm but considerably lower water levels in summer. Flooding began in 2010 with an MWGL of 36 cm above the surface. The fen was a net CO2 sink throughout all growing seasons (2009: -333.3 ± 12.3, 2010: -294.1 ± 8.4, 2011: -352.4 ± 5.1 g C m-2), but magnitudes of canopy photosynthesis (CP) and ecosystem respiration (Reco) differed distinctively. Rates of CP and Reco were high before flooding, dropped by 46% and 61%, respectively, in 2010, but increased again during the beginning of growing season 2011 until the water level started to rise further due to strong rainfalls during June and July. We assume that flooding decreases not only the CO2 release due to inhibited Reco under anaerobic conditions but also CO2 sequestration rates are constricted due to decreased CP. We conclude that rewetting might act as a disturbance for a plant community that has adapted to drier conditions after decades of drainage. However, if the recent species are still abundant, a rise in CP and autotrophic Reco can be expected after plants have developed plastic response strategies to wetter conditions.

  8. Turismo religioso: fenómeno social y económico

    Directory of Open Access Journals (Sweden)

    Sandra Maribel Tobón Perilla

    2013-11-01

    Full Text Available El turismo religioso, como fenómeno social y económico, ha cobrado interés entre académicos y empresarios por las dinámicas que ha generado en las comunidades receptoras de visitantes. Para los primeros, el interés radica en el estudio de las motivaciones, intereses y necesidades espirituales o culturales que parecen haber despertado los centros religiosos; para los segundos, el impacto económico y las oportunidades de rentas adicionales que generan los visitantes, creando nuevas oportunidades de negocios y fuentes de ingresos y empleo para las comunidades aledañas. Este documento hace una revisión a la bibliografía sobre el tema de turismo religioso en el mundo, para lo cual se consultaron las bases de datos ScienceDirect, Jstor, Ebsco, ProQuest y Google Académico, a fin de rastrear las publicaciones más relevantes y estudios empíricos sobre el tema, haciendo un recorrido desde 1963 hasta 2013. Se concluye que el turismo religioso es un fenómeno que tiene su antecedente en el peregrinaje a centros religiosos, pero donde además de las motivaciones, netamente religiosas –ofrecer un sacrificio, obtener un beneficio divino o expiar pecados–, existe un interés cultural, en términos de conocer centros históricos o profundizar sobre las raíces de un credo religioso. Adicionalmente, se observa cómo el turismo religioso se ha convertido en un motor de desarrollo económico de las ciudades receptoras de viajeros a sitios religioso.

  9. Turismo religioso: fenómeno social y económico

    Directory of Open Access Journals (Sweden)

    Sandra Maribel Tobón Perilla

    2013-12-01

    Full Text Available El turismo religioso, como fenómeno social y económico, ha cobrado interés entre académicos y empresarios por las dinámicas que ha generado en las comunidades receptoras de visitantes. Para los primeros, el interés radica en el estudio de las motivaciones, intereses y necesidades espirituales o culturales que parecen haber despertado los centros religiosos; para los segundos, el impacto económico y las oportunidades de rentas adicionales que generan los visitantes, creando nuevas oportunidades de negocios y fuentes de ingresos y empleo para las comunidades aledañas. Este documento hace una revisión a la bibliografía sobre el tema de turismo religioso en el mundo, para lo cual se consultaron las bases de datos ScienceDirect, Jstor, Ebsco, ProQuest y Google Académico, a fin de rastrear las publicaciones más relevantes y estudios empíricos sobre el tema, haciendo un recorrido desde 1963 hasta 2013. Se concluye que el turismo religioso es un fenómeno que tiene su antecedente en el peregrinaje a centros religiosos, pero donde además de las motivaciones, netamente religiosas –ofrecer un sacrificio, obtener un beneficio divino o expiar pecados–, existe un interés cultural, en términos de conocer centros históricos o profundizar sobre las raíces de un credo religioso. Adicionalmente, se observa cómo el turismo religioso se ha convertido en un motor de desarrollo económico de las ciudades receptoras de viajeros a sitios religioso.

  10. Upper ocean mixing controls the seasonality of planktonic foraminifer fluxes and associated strength of the carbonate pump in the oligotrophic North Atlantic

    Science.gov (United States)

    Salmon, K. H.; Anand, P.; Sexton, P. F.; Conte, M.

    2015-01-01

    Oligotrophic regions represent up to 75% of Earth's open-ocean environments. They are thus areas of major importance in understanding the plankton community dynamics and biogeochemical fluxes. Here we present fluxes of total planktonic foraminifera and 11 planktonic foraminifer species measured at the Oceanic Flux Program (OFP) time series site in the oligotrophic Sargasso Sea, subtropical western North Atlantic Ocean. Foraminifera flux was measured at 1500 m water depth, over two ~ 2.5-year intervals: 1998-2000 and 2007-2010. We find that foraminifera flux was closely correlated with total mass flux, carbonate and organic carbon fluxes. We show that the planktonic foraminifera flux increases approximately 5-fold during the winter-spring, contributing up to ~ 40% of the total carbonate flux. This was primarily driven by increased fluxes of deeper-dwelling globorotaliid species, which contributed up to 90% of the foraminiferal-derived carbonate during late winter-early spring. Interannual variability in total foraminifera flux, and in particular fluxes of the deep-dwelling species (Globorotalia truncatulinoides, Globorotalia hirsuta and Globorotalia inflata), was related to differences in seasonal mixed layer dynamics affecting the strength of the spring phytoplankton bloom and export flux, and by the passage of mesoscale eddies. As these heavily calcified, dense carbonate tests of deeper-dwelling species (3 times denser than surface dwellers) have greater sinking rates, this implies a high seasonality of the biological carbonate pump in oligotrophic oceanic regions. Our data suggest that climate cycles, such as the North Atlantic Oscillation, which modulates nutrient supply into the euphotic zone and the strength of the spring bloom, may also in turn modulate the production and flux of these heavily calcified deep-dwelling foraminifera by increasing their food supply, thereby intensifying the biological carbonate pump.

  11. Nutrient limitation and nutrient-driven shifts in plant species composition in a species-rich fen meadow

    NARCIS (Netherlands)

    Hoek, D. van der; Mierlo, A. van; Groenendael, J.M. van

    2004-01-01

    Question: We studied the development and persistence of the effects of nutrient pulses on biomass production and species composition in a fen meadow. Location: Nature reserve, central Netherlands, 5 m a.s.l. Methods: Single pulse fertilization with N and P in a factorial design on an undrained centr

  12. El fenómeno recurrente de Tsingou, Fermi, Pasta, Ulam y el Déjà vu

    Directory of Open Access Journals (Sweden)

    Máximo Agüero

    2010-01-01

    Full Text Available Se proporciona una visión divulgativa de la investigación para comprobar el teorema ergódico sobre la equiparticion de la energía en un sistema de muchos grados de libertad. Tsingou, Fermi, Pasta y Ulam (tfpu, en Los Álamos, New Mexico, durante los años de la segunda postguerra, estudiando el fenómeno de trasmisión de calor en sólidos y con el fin de comprobar el teorema ergódico, se apoyaron en cálculos numéricos sobre un sistema discreto de masas unidas por fuerzas no lineales. Encontraron un fenómeno extraño que fue denominado como fenómeno recurrente de tfpu. Esta investigación puso la primera piedra angular en el rápido desarrollo de la física nolineal con estructuras de ondas solitarias y también en el nuevo método de investigación mediante la experimentación numérica. El fenómeno recurrente podría tener su análogo en la sensación repentina fisiológica llamado "Déjà vu".

  13. Using stable isotopes of water to re-evaluate the recharge/discharge functions of North American bogs and fens

    Science.gov (United States)

    Levy, Zeno; Siegel, Donald; Glaser, Paul; Dasgupta, Soumitri

    2014-05-01

    In North American mires hydrologists commonly find raised bog crests and low-lying fen water tracks to be focal points for groundwater recharge and discharge, respectively. To further test these observations we synoptically surveyed vertical profiles of peat pore water δ18O/δ2H and major mineral solutes from a range of bog and fen landforms across the Glacial Lake Agassiz Peatlands (GLAP) of northern Minnesota. We also sampled a detailed transect through a 150 km2 bog-fen complex in the Red Lake II peatland watershed of the GLAP. The molar ratios of Ca/Mg in the pore water beneath the Red Lake II bog crest are depleted in Mg with respect to the atmospheric average of 3.6, indicative of preferential flushing of Mg from the peat by meteoric recharge. Higher solute concentrations in the middle of the peat profile at an adjacent fen show focused groundwater discharge with Ca/Mg ratios of ~1.4, similar to that of water from local wells tapping underlying glacial till. However, contrary to expectations, we find evidence that modern recharge has penetrated throughout the peat column beneath both bog and fen landforms throughout the GLAP. Landform surface features control the isotopic recharge value. These landform-specific isotope signatures propagate through vertical pore water profiles. Pore waters deeper than 0.5 m partition into discrete ranges of δ18O according to three a priori landform classifications: 1) -11.9 ± 0.4 o for bog crests, 2) -10.6 ± 0.1 o for Sphagnum lawns, and 3) -8.8 ± 1.0 o for fen water tracks. The fen water tracks have standing water at their surface that is seasonally enriched by isotope fractionating evaporation and therefore fingerprints recharge to depths ≥3 m. Incongruities between isotope and solute mixing trends may be related to the dual porosity nature of peat and matrix diffusion, which could supply solutes to active pore spaces following flushing by meteoric recharge. This buffering of base solutes in the deep peat may

  14. Carbon and nitrogen stable isotope ratios of pelagic zooplankton elucidate ecohydrographic features in the oligotrophic Red Sea

    KAUST Repository

    Kürten, Benjamin

    2015-11-10

    Although zooplankton occupy key roles in aquatic biogeochemical cycles, little is known about the pelagic food web and trophodynamics of zooplankton in the Red Sea. Natural abundance stable isotope analysis (SIA) of carbon (δ13C) and N (δ15N) is one approach to elucidating pelagic food web structures and diet assimilation Integrating the combined effects of ecological processes and hydrography, ecohydrographic features often translate into geographic patterns in δ13C and δ15N values at the base of food webs. This is due, for example, to divergent 15N abundances in source end-members (deep water sources: high δ15N, diazotrophs: low δ15N). Such patterns in the spatial distributions of stable isotope values were coined isoscapes. Empirical data of atmospheric, oceanographic, and biological processes, which drive the ecohydrographic gradients of the oligotrophic Red Sea, are under-explored and some rather anticipated than proven. Specifically, five processes underpin Red Sea gradients: a) monsoon-related intrusions of nutrient-rich Indian Ocean water; b) basin scale thermohaline circulation; c) mesoscale eddy activity that causes up-welling of deep water nutrients into the upper layer; d) the biological fixation of atmospheric nitrogen (N2) by diazotrophs; and e) the deposition of aerosol-derived N. This study assessed relationships between environmental samples (nutrients, chlorophyll a), oceanographic data (temperature, salinity, current velocity [ADCP]), particulate organic matter (POM), and net-phytoplankton, with the δ13C and δ15N values of zooplankton collected in spring 2012 from 16°28’ to 26°57’N along the central axis of the Red Sea. The δ15N of bulk POM and most zooplankton taxa increased from North (Duba) to South (Farasan). The potential contribution of deep water nutrient-fueled phytoplankton, POM, and diazotrophs varied among sites. Estimates suggested higher diazotroph contributions in the North, a greater contribution of POM in the South

  15. Carbon and nitrogen stable isotope ratios of pelagic zooplankton elucidate ecohydrographic features in the oligotrophic Red Sea

    Science.gov (United States)

    Kürten, Benjamin; Al-Aidaroos, Ali M.; Kürten, Saskia; El-Sherbiny, Mohsen M.; Devassy, Reny P.; Struck, Ulrich; Zarokanellos, Nikolaos; Jones, Burton H.; Hansen, Thomas; Bruss, Gerd; Sommer, Ulrich

    2016-01-01

    Although zooplankton occupy key roles in aquatic biogeochemical cycles, little is known about the pelagic food web and trophodynamics of zooplankton in the Red Sea. Natural abundance stable isotope analysis (SIA) of carbon (δ13C) and N (δ15N) is one approach to elucidating pelagic food web structures and diet assimilation. Integrating the combined effects of ecological processes and hydrography, ecohydrographic features often translate into geographic patterns in δ13C and δ15N values at the base of food webs. This is due, for example, to divergent 15N abundances in source end-members (deep water sources: high δ15N, diazotrophs: low δ15N). Such patterns in the spatial distributions of stable isotope values were coined isoscapes. Empirical data of atmospheric, oceanographic, and biological processes, which drive the ecohydrographic gradients of the oligotrophic Red Sea, are under-explored and some rather anticipated than proven. Specifically, five processes underpin Red Sea gradients: (a) monsoon-related intrusions of nutrient-rich Indian Ocean water; (b) basin scale thermohaline circulation; (c) mesoscale eddy activity that causes up-welling of deep water nutrients into the upper layer; (d) the biological fixation of atmospheric nitrogen (N2) by diazotrophs; and (e) the deposition of dust and aerosol-derived N. This study assessed relationships between environmental samples (nutrients, chlorophyll a), oceanographic data (temperature, salinity, current velocity [ADCP]), particulate organic matter (POM), and net-phytoplankton, with the δ13C and δ15N values of zooplankton collected in spring 2012 from 16°28‧ to 26°57‧N along the central axis of the Red Sea. The δ15N of bulk POM and most zooplankton taxa increased from North (Duba) to South (Farasan). The potential contribution of deep water nutrient-fueled phytoplankton, POM, and diazotrophs varied among sites. Estimates suggested higher diazotroph contributions in the North, a greater contribution of

  16. The hydrological and geochemical isolation of a freshwater bog within a saline fen in north-eastern Alberta

    Directory of Open Access Journals (Sweden)

    S.J. Scarlett

    2013-10-01

    Full Text Available In the oil sands development region near Fort McMurray, Alberta, wetlands cover ~62 % of the landscape, and ~95 % of these wetlands are peatlands. A saline fen was studied as a reference site for peatland reclamation. Despite highly saline conditions, a freshwater bog was observed in the path of local saline groundwater flow. The purpose of this study was to identify the hydrological controls that have allowed the development and persistence of a bog in this setting. The presence of bog vegetation and its dilute water chemistry suggest that saline groundwater from the fen rarely enters the bog, which functions predominantly as a groundwater recharge system. Chloride (Cl– and sodium (Na+ were the dominant ions in fen water, with concentrations averaging 5394 and 2307 mg L-1, respectively, while the concentrations in bog water were 5 and 4 mg L-1, respectively. These concentrations were reflected by salinity and electrical conductivity measurements, which in the fen averaged 9.3 ppt, and 15.8 mS cm-1, respectively, and in the bog averaged 0.1 ppt and 0.3 mS cm-1, respectively. A small ridge in the mineral substratum was found at the fen–bog margin, which created a persistent groundwater mound. Under the dry conditions experienced in early summer, groundwater flow was directed away from the bog at a rate of 14.6 mm day-1. The convex water table at the fen-bog margin impeded flow of saline water into the bog and instead directed it around the bog margin. However, the groundwater mound was eliminated during flooding in autumn, when the horizontal hydraulic gradient across the margin became negligible, suggesting the possibility of saline water ingress into the bog under these conditions.

  17. Greenhouse gas emissions from fen soils used for forage production in northern Germany

    Science.gov (United States)

    Poyda, Arne; Reinsch, Thorsten; Kluß, Christof; Loges, Ralf; Taube, Friedhelm

    2016-09-01

    A large share of peatlands in northwestern Germany is drained for agricultural purposes, thereby emitting high amounts of greenhouse gases (GHGs). In order to quantify the climatic impact of fen soils in dairy farming systems of northern Germany, GHG exchange and forage yield were determined on four experimental sites which differed in terms of management and drainage intensity: (a) rewetted and unutilized grassland (UG), (b) intensive and wet grassland (GW), (c) intensive and moist grassland (GM) and (d) arable forage cropping (AR). Net ecosystem exchange (NEE) of CO2 and fluxes of CH4 and N2O were measured using closed manual chambers. CH4 fluxes were significantly affected by groundwater level (GWL) and soil temperature, whereas N2O fluxes showed a significant relation to the amount of nitrate in top soil. Annual balances of all three gases, as well as the global warming potential (GWP), were significantly correlated to mean annual GWL. A 2-year mean GWP, combined from CO2-C eq. of NEE, CH4 and N2O emissions, as well as C input (slurry) and C output (harvest), was 3.8, 11.7, 17.7 and 17.3 Mg CO2-C eq. ha-1 a-1 for sites UG, GW, GM and AR, respectively (standard error (SE) 2.8, 1.2, 1.8, 2.6). Yield-related emissions for the three agricultural sites were 201, 248 and 269 kg CO2-C eq. (GJ net energy lactation; NEL)-1 for sites GW, GM and AR, respectively (SE 17, 9, 19). The carbon footprint of agricultural commodities grown on fen soils depended on long-term drainage intensity rather than type of management, but management and climate strongly influenced interannual on-site variability. However, arable forage production revealed a high uncertainty of yield and therefore was an unsuitable land use option. Lowest yield-related GHG emissions were achieved by a three-cut system of productive grassland swards in combination with a high GWL (long-term mean ≤ 20 cm below the surface).

  18. Holocene methane flux reconstruction from peat macrofossils at Siikaneva bog and fen, Finland

    Science.gov (United States)

    Mathijssen, Paul; Korrensalo, Aino; Tuittila, Eeva-Stiina; Väliranta, Minna; Mellais, Annina

    2015-04-01

    Previous studies have shown that a correlation exists between methane flux and peatland plant species abundance. Furthermore, it has been demonstrated that the composition of plant species or functional groups of species can be used as indicator for methane fluxes in peatlands, using weighted averaging. This method has the potential to be very useful in palaeoecological studies of peatlands as well. This method offers the possibility to reconstruct past methane flux based on vegetation remains still present in the peat archive and together with reconstructions of carbon accumulation can give a more complete picture of peatlands' carbon dynamics during the Holocene. Furthermore, effects of changes in hydrology or temperature on methane fluxes can be studied over much longer time scales, compared to what experimental setups allow for. For four peat cores from Siikaneva peatland in southern Finland, we reconstructed the methane flux during the Holocene. Two cores represent a part of the peatland that has currently a fen type vegetation. The other two cores were taken from a part of the peatland that has transformed into a bog, around 3.5 - 5.5 cal. year before present. The development of methane flux during the fen to bog transition is especially of interest. We used vegetation data and methane flux data from chamber measurement from all microtopographies found on Siikaneva and from a few similar peatlands in southern and central Finland as a training set. The plant species were classified into functional groups. Firstly, because it has been shown that usage of functional groups leads to better predictions of methane flux when compared to e.g. species or dominant species. Secondly, the information from the peat cores used as input for the reconstruction is based on progressively decomposed plant remains in subsequent peat layers, for which identification to species level is not always possible (most notably for sedges). We compare the predictive performance of two

  19. Compuestos fenólicos del olivo (Olea europea

    Directory of Open Access Journals (Sweden)

    Maestro-Durán, R.

    1994-08-01

    Full Text Available Certain plant properties, such as the colour, the nutritional value, the resistance to microorganisms, the pharmacologic effects and the organoleptic character, are due to the phenolic compounds. It is interesting the study of phenolic compounds from olive because they:

    -Inhibit Gram+ microorganisms, such as Lactobacillus, which are involved in the fermentation of the olive fruit. -Inhibit the activity of cellulases and other enzymes. -Contribute to the stability and organoleptic character of virgin olive oil. -Inhibit the effect of microorganisms involved in the anaerobic depuration of vegetation water. Thus, the phenolic compounds are the major bothersome contaminants of these wastewater. -Have pharmacologic properties (to reduce blood pressure levels. -Are natural antioxidants.

    In the present review we describe the composition of the phenolic compounds from the olive fruit (pulp and seed, the olive oil and its by-products (vegetation water and rape and the olive leaves.

    Ciertas propiedades de las plantas, como el color, valor nutricional, autoprotección contra microorganismos, propiedades farmacológicas o caracteres organolépticos, son debidas a los compuestos fenólicos. Su estudio, en el caso del olivo, es de gran interés por diversas razones:

    -Por su carácter antibiótico, los fenoles de la aceituna inhiben los microorganismos Gram+, como Lactobacillus, necesarios para la fermentación de aceitunas de mesa. -Inhiben la acción de las celulasas y otras enzimas. -Son los responsables de la alta estabilidad de los aceites vírgenes de oliva, así como de alguno de sus caracteres organolépticos. -Inhiben la acción de los microorganismos responsables de la depuración anaerobia de los alpechines y son las sustancias contaminantes de estas aguas residuales cuya degradación para eliminar la DQO presenta más dificultades. -Tienen propiedades

  20. Oral tolerance El fenómeno de la tolerancia oral

    Directory of Open Access Journals (Sweden)

    Martín Correa

    1989-03-01

    Full Text Available

    The phenomenon of decreased systemic Immune response to orally administered antigens is known as oral tolerance (OT. Though It was anecdotically described many years ago, the mechanisms and potential applications of OT are still mostly speculative. Specificity and thymus-dependence are among its most remarkable features. OT is manifested by the absence of systemic antibodies, of delayed type hypersensitivity and of proliferate responses toward the specific antigen. Potential mechanisms of OT have been grouped in three types, namely: Immunologic, gastrointestinal and individual. The most Important of the immunologic mechanisms might be the existence of counter-suppressive cells but their intimate functioning has not been thoroughly elucidated. The study of OT opens a wide research field with Implications for the immunoprophylaxis and Immunotherapy of many diseases.

    Se da el nombre de tolerancia oral al estado de respuesta inmune sistémica disminuida a antígenos administrados por la vía oral. Si bien el fenómeno fue descrito anecdóticamente desde hace muchos años, sus mecanismos y posibles aplicaciones todavía son materia de especulación. Entre sus características notables se destacan la especificidad y la timodependencia. La tolerancia se manifiesta por ausencia de anticuerpos sistémicos, de hipersensibilidad de tipo retardado y de respuestas proliferativas al antígeno específico. Los posibles mecanismos responsables de la tolerancia oral se han agrupado en tres tipos: inmunológicos, gastrointestinales e individuales. En cuanto a los inmunológicos, el más importante podría ser la existencia de las células contrasupresoras, pero los mecanismos íntimos de funcionamiento de éstas no están completamente elaborados. El estudio del fenómeno de la tolerancia oral abre un amplio campo

  1. Water level, vegetation composition, and plant productivity explain greenhouse gas fluxes in temperate cutover fens after inundation

    Science.gov (United States)

    Minke, Merten; Augustin, Jürgen; Burlo, Andrei; Yarmashuk, Tatsiana; Chuvashova, Hanna; Thiele, Annett; Freibauer, Annette; Tikhonov, Vitalij; Hoffmann, Mathias

    2016-07-01

    Peat extraction leaves a land surface with a strong relief of deep cutover areas and higher ridges. Rewetting inundates the deep parts, while less deeply extracted zones remain at or above the water level. In temperate fens the flooded areas are colonized by helophytes such as Eriophorum angustifolium, Carex spp., Typha latifolia or Phragmites australis dependent on water depth. Reeds of Typha and Phragmites are reported as large sources of methane, but data on net CO2 uptake are contradictory for Typha and rare for Phragmites. Here, we analyze the effect of vegetation, water level and nutrient conditions on greenhouse gas (GHG) emissions for representative vegetation types along water level gradients at two rewetted cutover fens (mesotrophic and eutrophic) in Belarus. Greenhouse gas emissions were measured campaign-wise with manual chambers every 2 to 4 weeks for 2 years and interpolated by modelling. All sites had negligible nitrous oxide exchange rates. Most sites were carbon sinks and small GHG sources. Methane emissions generally increased with net ecosystem CO2 uptake. Mesotrophic small sedge reeds with water table around the land surface were small GHG sources in the range of 2.3 to 4.2 t CO2 eq. ha-1 yr-1. Eutrophic tall sedge - Typha latifolia reeds on newly formed floating mats were substantial net GHG emitters in the range of 25.1 to 39.1 t CO2 eq. ha-1 yr. They represent transient vegetation stages. Phragmites reeds ranged between -1.7 to 4.2 t CO2 eq. ha-1 yr-1 with an overall mean GHG emission of 1.3 t CO2 eq. ha-1 yr-1. The annual CO2 balance was best explained by vegetation biomass, which includes the role of vegetation composition and species. Methane emissions were obviously driven by biological activity of vegetation and soil organisms. Shallow flooding of cutover temperate fens is a suitable measure to arrive at low GHG emissions. Phragmites australis establishment should be promoted in deeper flooded areas and will lead to moderate, but

  2. El patrimonio como fenómeno socio-cultural y su contextualización

    Directory of Open Access Journals (Sweden)

    Nurys de los Angeles Valcárcel Leyva

    2011-01-01

    Full Text Available El humanista del presente requiere sólidas bases académicas, que le permitan desarrollar la práctica de enfrentamiento a la aculturación neoliberal. Se ofrecen análisis y valoraciones en torno al patrimonio, los cuales se consideran referentes que fundamentan científicamente la necesidad del sujeto cultural de defender su pertenencia identitaria. El patrimonio se aborda como fenómeno que se desarrolla a instancias del proceso de relaciones entre sociedad y cultura, como resultado de la contradicción conservaciónrenovación inherente al desarrollo humano. Las formulaciones conceptuales y de reconceptualización, se presentan desde la apoyatura científica que ofrecen ciencias particulares como la filosofía, antropología, sociología y otras, éstas contribuyen a la interpretación y análisis crítico-reflexivo de la relación patrimonioidentidad- contexto sociocultural, a partir del dimensionamiento ontológico, gnoseológico y axiológico de los valorespatrimoniales, todo lo cual aporta recursos cognoscitivos y axiológicos válidos para favorecer la formación y desarrollo de un sujeto cultural que refrende su pertenencia identitaria.

  3. El sesgo de subconfianza como fenómeno de dominio específico

    Directory of Open Access Journals (Sweden)

    Guillermo Macbeth

    2009-01-01

    Full Text Available Se define la calibración o confianza como la coincidencia o discrepancia entre el éxito subjetivo y el éxito objetivo que presenta una persona en la realización de una colecci ón de tareas. Las discrepancias entre uno y otro generan distorsiones conocidas como sesgos de la calibración. Cuando el éxito subjetivo predomina sobre el éxito objetivo se observa el sesgo de sobreconfianza. En el caso contrario, se observa el sesgo de subconfianza. Se presenta un estudio experimental que intenta decidir si el dominio es relevante para la disolución del sesgo de subconfianza. Los resultados indican que el domino es efectivamente relevante para reducir y eliminar esta distorsi ón del pensamiento humano. La exposición de los participantes a un modelo metacognitivo de calibración de domino específico logró disolver el sesgo. Cuando se empleó un modelo de dominio no específico, en cambio, el sesgo no se disolvió sino que se invirtió produciendo el sesgo de sobreconfianza. Se concluye que el sesgo de subconfianza es un fenómeno metacognitivo de dominio específico.

  4. As "propagandas do horror" e os fenômenos de massa contemporâneos

    Directory of Open Access Journals (Sweden)

    Ana Paula Avila Gomide

    2011-12-01

    Full Text Available Este trabalho teórico discute os fundamentos ligados a certas disposições psíquicas que subjazem aos fenômenos de massa contemporâneos, a partir da relação estabelecida entre o conto "Os Anões" e as propagandas antifumo, as denominadas "propagandas do terror", as quais são transmitidas por imagens que mostram o processo de definhamento e de decomposição do fumante. OS referenciais teóricos adotados são Theodor Adorno, Max Horkheimer e SigmundFreud. Pressupõe-se que, para a análise tanto do subtexto das mensagens quanto do conto, a tese sobre a história subterrânea do esclarecimento voltada à dominação do corpo e da natureza, e mais do "retorno do recalcado", lança luz sobre os elementos investigados.

  5. Carbonaceous thin film coating with Fe-N4 site for enhancement of dioxovanadium ion reduction

    Science.gov (United States)

    Maruyama, Jun; Hasegawa, Takahiro; Iwasaki, Satoshi; Fukuhara, Tomoko; Orikasa, Yuki; Uchimoto, Yoshiharu

    2016-08-01

    It has been found that carbonaceous materials containing a transition metal coordinated by 4 nitrogens in the square-planar configuration (metal-N4 site) on the surface possessed a catalytic activity for various electrochemical reactions related to energy conversion and storage; i.e., oxygen reduction, hydrogen evolution, and quite recently, the electrode reactions in vanadium redox flow batteries (VRFB). The catalyst for the VRFB positive electrode discharge reaction, i.e., the dioxovanadium ion reduction, was formed by coating the surface of cup-stack carbon nanotubes with a carbonaceous thin film with the Fe-N4 site generated by the sublimation, deposition, and pyrolysis of iron phthalocyanine. In this study, the influence of the physical properties of the catalyst on the electrochemical reactions was investigated to optimize the coating. With an increase in the coating, the specific surface area increased, whereas the pore size decreased. The surface Fe concentration was increased in spite of the Fe aggregation inside the carbon matrix. The catalytic activity enhancement was achieved due to the increase in the specific surface area and the surface Fe concentration, but was lowered due to the decrease in the pore size, which was disadvantageous for the penetration of the electrolyte and the mass transfer.

  6. El fenómeno del Greenwashing y su impacto sobre los consumidores

    Directory of Open Access Journals (Sweden)

    Moritz Hallama

    2011-07-01

    Full Text Available Hoy en día y mediante una publicidad sofisticada, las empresas tratan de proyectar una imagen respetuosa con el medio ambiente en la percepción de los consumidores. Esta imagen no refleja necesariamente la realidad. Se habla de “Greenwashing” cuando una empresa utiliza la ampliación selectiva de información medioambiental positiva con la finalidad de causar una imagen distorsionada donde los aspectos positivos predominan mas del debido. Este artículo pretende de abordar este fenómeno y avaluar su existencia, importancia y el efecto causado sobre los consumidores mediante el diseño de una metodología piloto para la investigación, aplicando ésta a una muestra de estudiantes. Los resultados indican que la imagen transmitida por la publicidad de cinco grandes empresas seleccionadas contrasta con ejemplos de mala gestión y que esta manipulación influye en la percepción que tiene la muestra encuestada. Los estudiantes de Ciencias Ambientales encuestados presentan ser ligeramente más resistentes contra el Greenwashing debido a su formación, pero también incorporan mayoritariamente el discurso oficial procedente de las relaciones públicas empresariales.

  7. Seasonal dynamics of methane emissions from a subarctic fen in the Hudson Bay Lowlands

    Directory of Open Access Journals (Sweden)

    K. L. Hanis

    2013-03-01

    Full Text Available Ecosystem-scale methane (CH4 flux (FCH4 over a subarctic fen at Churchill, Manitoba, Canada was measured to understand the magnitude of emissions during spring and fall shoulder seasons, and the growing season in relation to physical and biological conditions. FCH4 was measured using eddy covariance with a closed-path analyzer in four years (2008–2011. Cumulative measured annual FCH4 (shoulder plus growing seasons ranged from 3.0 to 9.6 g CH4 m−2 yr−1 among the four study years, with a mean of 6.5 to 7.1 g CH4 m−2 yr−1 depending upon gap-filling method. Soil temperatures to depths of 50 cm and air temperature were highly correlated with FCH4, with near surface soil temperature at 5 cm most correlated across spring, fall, and the whole season. The response of FCH4 to soil temperature at the 5 cm depth and air temperature was more than double in spring to that of fall. Emission episodes were generally not observed during spring thaw. Growing season emissions also depended upon soil and air temperatures but water table also exerted influence with FCH4 highest when water was 2–13 cm below and least when it was at or above the mean peat surface.

  8. Efectos ecológicos del fenómeno ENOS en Colombia

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    Yesid Carvajal

    2014-06-01

    Full Text Available El fenómeno ENOS, tiene un sustancial efecto sobre las variaciones del clima a nivel mundial; por lo tanto, no sorprende que sus efectos tengan un impacto ecológico y socioeconómico fuerte, alterando la seguridad alimentaria de los países a nivel mundial. Ante este panorama, es comprensible que haya despertado el mayor interés mundial, no sólo en los especialistas en meteorología y oceanografía sino también entre biólogos, ecólogos, físicos, matemáticos, agrónomos, hidrólogos, economistas, sociólogos y planificadores, entre otros. En el presente documento, se muestra algunos de los principales efectos ecológicos en Colombia durante las fases extremas cálida (El Niño y fría (La Niña, indicando que es una necesidad urgente, orientar la investigación en sus causas, consecuencias e impactos.

  9. Seasonal dynamics of methane emissions from a subarctic fen in the Hudson Bay Lowlands

    Science.gov (United States)

    Hanis, K. L.; Tenuta, M.; Amiro, B. D.; Papakyriakou, T. N.

    2013-07-01

    Ecosystem-scale methane (CH4) flux (FCH4) over a subarctic fen at Churchill, Manitoba, Canada was measured to understand the magnitude of emissions during spring and fall shoulder seasons, and the growing season in relation to physical and biological conditions. FCH4 was measured using eddy covariance with a closed-path analyser in four years (2008-2011). Cumulative measured annual FCH4 (shoulder plus growing seasons) ranged from 3.0 to 9.6 g CH4 m-2 yr-1 among the four study years, with a mean of 6.5 to 7.1 g CH4 m-2 yr-1 depending upon gap-filling method. Soil temperatures to depths of 50 cm and air temperature were highly correlated with FCH4, with near-surface soil temperature at 5 cm most correlated across spring, fall, and the shoulder and growing seasons. The response of FCH4 to soil temperature at the 5 cm depth and air temperature was more than double in spring to that of fall. Emission episodes were generally not observed during spring thaw. Growing season emissions also depended upon soil and air temperatures but the water table also exerted influence, with FCH4 highest when water was 2-13 cm below and lowest when it was at or above the mean peat surface.

  10. Seasonal dynamics of methane emissions from a subarctic fen in the Hudson Bay Lowlands

    Directory of Open Access Journals (Sweden)

    K. L. Hanis

    2013-07-01

    Full Text Available Ecosystem-scale methane (CH4 flux (FCH4 over a subarctic fen at Churchill, Manitoba, Canada was measured to understand the magnitude of emissions during spring and fall shoulder seasons, and the growing season in relation to physical and biological conditions. FCH4 was measured using eddy covariance with a closed-path analyser in four years (2008–2011. Cumulative measured annual FCH4 (shoulder plus growing seasons ranged from 3.0 to 9.6 g CH4 m−2 yr−1 among the four study years, with a mean of 6.5 to 7.1 g CH4 m−2 yr−1 depending upon gap-filling method. Soil temperatures to depths of 50 cm and air temperature were highly correlated with FCH4, with near-surface soil temperature at 5 cm most correlated across spring, fall, and the shoulder and growing seasons. The response of FCH4 to soil temperature at the 5 cm depth and air temperature was more than double in spring to that of fall. Emission episodes were generally not observed during spring thaw. Growing season emissions also depended upon soil and air temperatures but the water table also exerted influence, with FCH4 highest when water was 2–13 cm below and lowest when it was at or above the mean peat surface.

  11. Atividade antioxidante e teor de fenólicos totais em hortaliças orgânicas e convencionais Antioxidant activity and phenolic content in organic and conventional vegetables

    Directory of Open Access Journals (Sweden)

    Kettelin Aparecida Arbos

    2010-06-01

    Full Text Available Considerando que os consumidores estão mais conscientes com a sua saúde e mais preocupados com as condições ambientais, verifica-se uma crescente demanda por alimentos orgânicos. O objetivo deste estudo foi comparar a atividade antioxidante e o teor de fenólicos totais entre alface, rúcula e almeirão de cultivos orgânico e convencional, plantados em uma mesma horta. A atividade antioxidante dos extratos metanólicos das hortaliças foi determinada através do ensaio do DPPH. O teor de fenólicos totais foi obtido espectrofotometricamente de acordo com o método de Folin-Ciocalteu e calculado como equivalente de ácido gálico. A atividade antioxidante contra o radical livre DPPH foi: rúcula orgânica > almeirão orgânico > alface orgânica > rúcula convencional > almeirão convencional > alface convencional. O teor de fenólicos totais foi superior nos vegetais orgânicos. Os resultados deste estudo sugerem que as hortaliças orgânicas podem ser uma importante fonte de antioxidantes naturais e de compostos fenólicos e, portanto, seu consumo deve ser estimulado.Considering that consumers are becoming more conscious of their health and more concerned with environmental conditions, there has been an increasing demand for organic foods. The aim of this study was to compare the antioxidant activity and determine the total phenolic content of organic and conventional cultivations of lettuce, arugula, and chicory grown in the same vegetable garden. The antioxidant activity of the methanol extracts of these leaf vegetables wasdetermined using DPPH free radical scavenging assay. The total phenolic content in the extracts was determined spectrometrically according to the Folin-Ciocalteu method and calculated as equivalent of gallic acid. The antioxidant activity against the DPPH free radical was: organic arugula> organic chicory > organic lettuce > conventional arugula > conventional chicory > conventional lettuce. The total phenolic content

  12. Cambios en contenido de compuestos fenólicos y color de extractos de Jamaica (Hibiscus sabdariffa) sometidos a calentamiento con energía de microondas

    OpenAIRE

    Hid Cadena, Rebeca; Bautista Ortín, Ana Belén; Ortega Regules, Ana E.; Welti Chanes, Jorge S.; Lozada Ramírez, J. Daniel; Anaya de Parrodi, Cecilia

    2010-01-01

    En este trabajo se realizó la extracción acuosa de compuestos fenólicos, principalmente antocianinas, provenientes de cálices de jamaica (Hibiscus sabdariffa). El extracto fue calentado por microondas a diferentes temperaturas (30, 40, 50, 60, 70 y 80°C) durante 20 min, tomando una alícuota cada 5 min. En el extracto con y sin calentamiento se determinó el contenido de compuestos fenólicos y los parámetros colorimétricos. Para el contenido de compuestos fenólicos totales se observaron pérdida...

  13. Extracción de compuestos fenólicos de la uva al vino. Papel de los enzimas de maceración

    OpenAIRE

    Romero Cascales, María Inmaculada

    2008-01-01

    La extracción de los compuestos fenólicos, responsables de ciertas características de color de los vinos, va a depender entre otros, de la degradación de la pared celular, por lo que el uso de enzimas pectolíticos podría ser una técnica adecuada para obtener vinos con mayor carga polifenólica. Los resultados mostraron que la extracción de los compuestos fenólicos durante la maceración es incompleta. Además, estudiando la extractabilidad de los compuestos fenólicos en diferentes variedade...

  14. Fenólicos totais e atividade antioxidante do extrato aquoso de broto de feijão-mungo (Vigna radiata L. Total phenolics and antioxidant activity of the aqueous extract of mung bean sprout (Vigna radiata L.

    Directory of Open Access Journals (Sweden)

    Vera Lúcia Arroxelas Galvão de Lima

    2004-03-01

    Full Text Available OBJETIVO: Considerando a importância dos compostos fenólicos em alimentos e que o broto de feijão-mungo vem sendo incluído na culinária brasileira, este estudo teve como objetivo quantificar o teor de fenólicos totais deste vegetal e avaliar a ação antioxidante do seu extrato aquoso. MÉTODOS: Os compostos fenólicos foram extraídos por quatro sistemas de solventes e dois métodos de extração, os quais foram diferenciados no tempo (2 e 1h e número de extrações (2 e 3 extrações. Os fenólicos totais dos extratos foram quantificados por método espectrofotométrico. RESULTADOS: Os extratos obtidos com água à temperatura ambiente (28ºC, nos dois métodos de extração, foram os que apresentaram maior quantidade de fenólicos totais, sem contudo apresentar diferença significativa entre eles. O método II, que consistiu de três extrações em 1h, pode ser considerado o melhor por ter utilizado menor tempo de extração. O extrato aquoso em sistema modelo b-caroteno/ácido linoléico exibiu ação antioxidante (48,07% de inibição da oxidação, entretanto foi inferior ao padrão BHT. CONCLUSÃO: O broto de feijão-mungo possui considerável quantidade de fenólicos totais, compostos responsáveis por sua ação antioxidante, cujo consumo pode proporcionar efeitos benéficos à saúde.OBJECTIVE: Considering the importance of phenolic compounds in foods and the increasing consumption of mung bean sprouts in Brazil, this study had the objective of quantifying the total phenolic content in this vegetable and to assess the antioxidant activity of its aqueous extract. METHODS: The phenolic compounds were extracted by four solvent systems and two extraction methods, which were different in time (2 and 1h and in number of extractions (2 and 3 extractions. The total phenolic content of the extracts were quantified by the spectrophotometric method. RESULTS: The extracts obtained with water at room temperature (28ºC in both extraction

  15. Biodegradación de compuestos fenólicos del alpechín con Aspergillus terreus

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    García Paeja, María P.

    1992-04-01

    Full Text Available Olive mill wastewater degradation by Aspergillus terreus and under aerobic conditions at 28°C, was measured by the parameter of phenol content. We have explored the effect of different concentrations of olive mill wastewater upon the activity of Aspergillus terreus. Through HPLC, 10 phenol compounds (90% of the total phenolic content of the olive mill wastewater were identified.Se estudia la degradación de alpechines con Aspergillus terreus en condiciones de aerobiosis y temperatura de 28°C, utilizando como parámetro el contenido fenólico. Se analiza el efecto de la concentración de alpechín con Aspergillus terreus utilizando el mismo parámetro. Se han identificado por cromatografía líquida de alta eficacia (CLAE 10 compuestos fenólicos que suponen el 90% del total del alpechín.

  16. El fenómeno de la migración en aves: una mirada desde la Orinoquia

    OpenAIRE

    Ocampo-Peñuela, Natalia

    2010-01-01

    La migración es un fenómeno que ha llamado la atención de investigadores a lo largo del mundo y de la historia de la ciencia. Este proceso biológico ha sido bien estudiado en aves, sin embargo, en Colombia y, especialmente en la región de la Orinoquia, aún queda mucho por conocer sobre estas viajeras. Este artículo presenta el fenómeno de la migración Neotropical en aves; primero se evidencia una recopilación de bibliografía sobre la migración en aves y algunos de sus aspectos más...

  17. The hydrological and geochemical isolation of a freshwater bog within a saline fen in north-eastern Alberta

    OpenAIRE

    S.J. Scarlett; J.S. Price

    2013-01-01

    In the oil sands development region near Fort McMurray, Alberta, wetlands cover ~62 % of the landscape, and ~95 % of these wetlands are peatlands. A saline fen was studied as a reference site for peatland reclamation. Despite highly saline conditions, a freshwater bog was observed in the path of local saline groundwater flow. The purpose of this study was to identify the hydrological controls that have allowed the development and persistence of a bog in this setting. The presence of bog veget...

  18. Reclutamiento de niños y niñas: fenómeno invisibilizado, crimen manifiesto

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    Verónica Hinestroza-Arenas

    2008-11-01

    Full Text Available En los últimos 15 años la comunidad internacional ha dirigido esfuerzos importantes para llamar la atención sobre las dimensiones mundiales del fenómeno del reclutamiento de niños y niñas y su uso en hostilidades. Dichos esfuerzos se han materializado en convenciones, protocolos y principios para la protección de la infancia y la penalización de la

  19. Uso de compuestos fenólicos para el tratamiento de patologías causadas por Helicobacter pylori

    OpenAIRE

    Carrascosa, Alfonso V.; Martínez-Rodríguez, Adolfo J.; López-Brea, Manuel; Alarcón, Teresa; Rodrigo, Sandra

    2010-01-01

    La presente invención se refiere a una serie de compuestos fenólicos que pueden ser extraídos de la uva o del vino y que poseen capacidad bacericida contra Helicobacter pylori, por lo que dichos compuestos son útiles para la fabricación de un medicamento para el tratamiento y/o prevención de patologías causadas por esta bacteria o como aditivos en alimentos funcionales o productos alimentarios.

  20. Uso de compuestos fenólicos para el tratamiento de patologías causadas por helicobacter pylori

    OpenAIRE

    Carrascosa, Alfonso V.; Martínez-Rodríguez, Adolfo J.; López-Brea, Manuel; Alarcón, Teresa; Rodrigo, Sandra

    2010-01-01

    [ES] La presente invención se refiere a una serie de compuestos fenólicos que pueden ser extraídos de la uva o del vino y que poseen capacidad bactericida contra Helicobacter pylori, por lo que dichos compuestos son útiles para la fabricación de un medicamento para el tratamiento y/o prevención de patologías causadas por esta bacteria o como aditivos en alimentos funcionales o productos alimentarios.

  1. A cryptic targeting signal creates a mitochondrial FEN1 isoform with tailed R-Loop binding properties.

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    Lawrence Kazak

    Full Text Available A growing number of DNA transacting proteins is found in the nucleus and in mitochondria, including the DNA repair and replication protein Flap endonuclease 1, FEN1. Here we show a truncated FEN1 isoform is generated by alternative translation initiation, exposing a mitochondrial targeting signal. The shortened form of FEN1, which we term FENMIT, localizes to mitochondria, based on import into isolated organelles, immunocytochemistry and subcellular fractionation. In vitro FENMIT binds to flap structures containing a 5' RNA flap, and prefers such substrates to single-stranded RNA. FENMIT can also bind to R-loops, and to a lesser extent to D-loops. Exposing human cells to ethidium bromide results in the generation of RNA/DNA hybrids near the origin of mitochondrial DNA replication. FENMIT is recruited to the DNA under these conditions, and is released by RNase treatment. Moreover, high levels of recombinant FENMIT expression inhibit mtDNA replication, following ethidium bromide treatment. These findings suggest FENMIT interacts with RNA/DNA hybrids in mitochondrial DNA, such as those found at the origin of replication.

  2. In vitro anti-coxsackievirus B3 effect of ethyl acetate extract of Tian-hua-fen

    Institute of Scientific and Technical Information of China (English)

    Zhen-Hong Li; Bao-Ming Nie; Hong Chen; Shu-Yun Chen; Ping He; Yang Lu; Xiao-Kui Guo; Jing-Xing Liu

    2004-01-01

    AIM: To investigation the anti-coxsackievirus B3 (CVB3m)effect of the ethyl acetate extract of Tian-hua-fen on HeLa cells infected with CVB3m.METHODS: HeLa cells were infected with CVB3m and the cytopathic effects (CPE) were observed through light microscope and crystal violet staining on 96-well plate and A600 was detected using spectrophotometer. The protective effect of the extract to HeLa cells and the mechanism of the effect were also evaluated through the change of CPE and value of A600.RESULTS: The extract had some toxicity to HeLa cells at a higher concentration while had a marked inhibitory effect on cell pathological changes at a lower concentration.Consistent results were got through these two methods.We also investigated the mechanism of its anti-CVB3m effect and the results indicated that the extract represented an inhibitory effect through all the processes of CVB3m attachment, entry, biosynthesis and assemble in cells.CONCLUSION: The results demonstrate that the ethyl acetate extract of Tian-hua-fen has a significant protective effect on HeLa cells infected with CVB3m in a dose-dependent manner and this effect exists through the process of CVB3m attachment, entry, biosynthesis and assemble in cells,suggesting that the ethyl acetate extract of Tian-hua-fen can be developed as an anti-virus agent.

  3. Recent rates of carbon accumulation in montane fens ofYosemite National Park, California, U.S.A.

    Science.gov (United States)

    Drexler, Judith; Fuller, Christopher C.; Orlando, James; Moore, Peggy E.

    2016-01-01

    Little is known about recent rates of carbon storage in montane peatlands, particularly in the western United States. Here we report on recent rates of carbon accumulation (past 50 to 100 years) in montane groundwater-fed peatlands (fens) of Yosemite National Park in central California, U.S.A. Peat cores were collected at three sites ranging in elevation from 2070 to 2500 m. Core sections were analyzed for bulk density, % organic carbon, and 210Pb activities for dating purposes. Organic carbon densities ranged from 0.026 to 0.065 g C cm-3. Mean vertical accretion rates estimated using210Pb over the 50-year period from ∼1960 to 2011 and the 100-year period from ∼1910 to 2011 were 0.28 (standard deviation = ±0.09) and 0.18 (±-0.04) cm yr-1, respectively. Mean carbon accumulation rates over the 50- and 100-year periods were 95.4 (±25.4) and 74.7 (±17.2) g C m-2 yr-1, respectively. Such rates are similar to recent rates of carbon accumulation in rich fens in western Canada, but more studies are needed to definitively establish both the similarities and differences in peat formation between boreal and temperate montane fens.

  4. Variability of rRNA operon copy number and growth rate dynamics of Bacillus isolated from an extremely oligotrophic aquatic ecosystem

    Directory of Open Access Journals (Sweden)

    Jorge Antonio Valdivia-Anistro

    2016-01-01

    Full Text Available The ribosomal RNA (rrn operon is a key suite of genes related to the production of protein synthesis machinery and thus to bacterial growth physiology. Experimental evidence has suggested an intrinsic relationship between the number of copies of this operon and environmental resource availability, especially the availability of phosphorus (P, because bacteria that live in oligotrophic ecosystems usually have few rrn operons and a slow growth rate. The Cuatro Ciénegas Basin (CCB is a complex aquatic ecosystem that contains an unusually high microbial diversity that is able to persist under highly oligotrophic conditions. These environmental conditions impose a variety of strong selective pressures that shape the genome dynamics of their inhabitants. The genus Bacillus is one of the most abundant cultivable bacterial groups in the CCB and usually possesses a relatively large number of rrn operon copies (6-15 copies. The main goal of this study was to analyze the variation in the number of rrn operon copies of Bacillus in the CCB and to assess their growth-related properties as well as their stoichiometric balance (N and P content. We defined 18 phylogenetic groups within the Bacilli clade and documented a range of from six to 14 copies of the rrn operon. The growth dynamic of these Bacilli was heterogeneous and did not show a direct relation to the number of operon copies. Physiologically, our results were not consistent with the Growth Rate Hypothesis, since the copies of the rrn operon were decoupled from growth rate. However, we speculate that the diversity of the growth properties of these Bacilli as well as the low P content of their cells in an ample range of rrn copy number is an adaptive response to oligotrophy of the CCB and could represent an ecological mechanism that allows these taxa to coexist. These findings increase the knowledge of the variability in the number of copies of the rrn operon in the genus Bacillus and give insights

  5. Methanotrophic and Methanogenic Communities in Swiss Alpine Fens Dominated by Carex rostrata and Eriophorum angustifolium.

    Science.gov (United States)

    Cheema, Simrita; Zeyer, Josef; Henneberger, Ruth

    2015-09-01

    Vascular plants play a key role in controlling CH4 emissions from natural wetlands, because they influence CH4 production, oxidation, and transport to the atmosphere. Here we investigated differences in the abundance and composition of methanotrophic and methanogenic communities in three Swiss alpine fens dominated by different vascular plant species under natural conditions. The sampling locations either were situated at geographically distinct sites with different physicochemical properties but the same dominant plant species (Carex rostrata) or were located within the same site, showing comparable physicochemical pore water properties, but had different plant species (C. rostrata or Eriophorum angustifolium). All three locations were permanently submerged and showed high levels of CH4 emissions (80.3 to 184.4 mg CH4 m(-2) day(-1)). Soil samples were collected from three different depths with different pore water CH4 and O2 concentrations and were analyzed for pmoA and mcrA gene and transcript abundance and community composition, as well as soil structure. The dominant plant species appeared to have a significant influence on the composition of the active methanotrophic communities (transcript level), while the methanogenic communities differed significantly only at the gene level. Yet no plant species-specific microbial taxa were discerned. Moreover, for all communities, differences in composition were more pronounced with the site (i.e., with different physicochemical properties) than with the plant species. Moreover, depth significantly influenced the composition of the active methanotrophic communities. Differences in abundance were generally low, and active methanotrophs and methanogens coexisted at all three locations and depths independently of CH4 and O2 concentrations or plant species. PMID:26092454

  6. Carbon dioxide fluxes at an intensively cultivated temperate lowland peatland in the East Anglian Fens, UK

    Directory of Open Access Journals (Sweden)

    R. Morrison

    2013-03-01

    Full Text Available This study reports the first recorded CO2 flux measurements of a drained and intensively cultivated lowland peatland in the East Anglian Fens (UK using the eddy covariance technique. Measurements were made over a complete lettuce crop rotation and a subsequent fallow period. Maximum average daytime CO2 uptake and nocturnal loss rates were −10.39 and 7.63 μmol CO2 m−2 s−1, respectively. Daily CO2 budgets ranged from a net loss of 4.7 to a small net uptake of −1.23 g CO2-C m−2 d−1. Total vertical land/atmosphere CO2 losses were estimated at 227.11 ± 46.5 g CO2-C m−2 for a~120 day measurement period. Losses over a sixty day interval between field preparation and disking of the field at the end of the crop cycle were 74.22 ± 18.8 g CO2-C m−2. The site lost 152.89 ± 30.6 g CO2-C m−2 d−1 during a sixty day fallow period. Net ecosystem production was estimated at 117.72 ± 18.8 g CO2-C m−2 during the crop cycle and 270.61 ± 46.49 g CO2-C m−2 for the entire measurement period when harvested crop exports were accounted for. These results represent the first micrometeorological measurements obtained over degraded lowland peatland in Britain, and illustrate the scale of CO2 losses associated with agricultural production on temperate organic soils.

  7. Evaluating governance for sustainable development - Insights from experiences in the Dutch fen landscape.

    Science.gov (United States)

    den Uyl, Roos M; Driessen, Peter P J

    2015-11-01

    Prominent strands of discussion in the literature on governance for sustainable development debate how change can be induced to enhance sustainability, and how to evaluate the interventions aimed at prompting such change. Strikingly, there are few contributions about how prominent ideas of inducing change deal with multiple governance criteria for pursuing sustainable development. Moreover, the way ideas about inducing change relate to criteria of governance for sustainable development is not yet studied in an empirical context. This paper therefore comparatively analyses how three prominent modes of sustainable development governance - adaptive management, transition management and payments for environmental services - relate to a set of five prominent criteria reported in the literature, namely: equity, democracy, legitimacy, the handling of scale issues and the handling of uncertainty issues. It finds that the academic debates on these three modes address these criteria with varying attention and rather fragmented, while in the empirical setting of the Dutch fen landscape several aspects relating to the studied criteria were present and substantially influenced the functioning of the three modes of sustainable development. Together, the analysis of the literature debate and the empirical data are able to show that a narrow evaluation perspective may fail to diagnose and capture relevant struggles and complexities coming along with governance for sustainable development relevant issues. The study shows that in order to advance our understanding of governance for sustainable development, it is indeed important to include multiple criteria in studying these modes. Moreover, the study shows the importance of including empirical experiences which manifest when different modes for sustainable development are applied in real-world settings.

  8. Filtering fens: mechanisms explaining phosphorus-limited hotspots of biodiversity in wetlands adjacent to heavily fertilized areas.

    Science.gov (United States)

    Cusell, Casper; Kooijman, Annemieke; Fernandez, Filippo; van Wirdum, Geert; Geurts, Jeroen J M; van Loon, E Emiel; Kalbitz, Karsten; Lamers, Leon P M

    2014-05-15

    The conservation of biodiverse wetland vegetation, including that of rich fens, has a high priority at a global scale. Although P-eutrophication may strongly decrease biodiversity in rich fens, some well-developed habitats do still survive in highly fertilized regions due to nutrient filtering services of large wetlands. The occurrence of such nutrient gradients is well-known, but the biogeochemical mechanisms that determine these patterns are often unclear. We therefore analyzed chemical speciation and binding of relevant nutrients and minerals in surface waters, soils and plants along such gradients in the large Ramsar nature reserve Weerribben-Wieden in the Netherlands. P-availability was lowest in relatively isolated floating rich fens, where plant N:P ratios indicated P-limitation. P-limitation can persist here despite high P-concentrations in surface waters near the peripheral entry locations, because only a small part of the P-input reaches the more isolated waters and fens. This pattern in P-availability appears to be primarily due to precipitation of Fe-phosphates, which mainly occurs close to entry locations as indicated by decreasing concentrations of Fe- and Al-bound P in the sub-aquatic sediments along this gradient. A further decrease of P-availability is caused by biological sequestration, which occurs throughout the wetland as indicated by equal concentrations of organic P in all sub-aquatic sediments. Our results clearly show that the periphery of large wetlands does indeed act as an efficient P-filter, sustaining the necessary P-limitation in more isolated parts. However, this filtering function does harm the ecological quality of the peripheral parts of the reserve. The filtering mechanisms, such as precipitation of Fe-phosphates and biological uptake of P, are crucial for the conservation and restoration of biodiverse rich fens in wetlands that receive eutrophic water from their surroundings. This seems to implicate that biodiverse wetland

  9. Denitrification activity of a remarkably diverse fen denitrifier community in finnish lapland is N-oxide limited.

    Science.gov (United States)

    Palmer, Katharina; Horn, Marcus A

    2015-01-01

    Peatlands cover more than 30% of the Finnish land area and impact N2O fluxes. Denitrifiers release N2O as an intermediate or end product. In situ N2O emissions of a near pH neutral pristine fen soil in Finnish Lapland were marginal during gas chamber measurements. However, nitrate and ammonium fertilization significantly stimulated in situ N2O emissions. Stimulation with nitrate was stronger than with ammonium. N2O was produced and subsequently consumed in gas chambers. In unsupplemented anoxic microcosms, fen soil produced N2O only when acetylene was added to block nitrous oxide reductase, suggesting complete denitrification. Nitrate and nitrite stimulated denitrification in fen soil, and maximal reaction velocities (vmax) of nitrate or nitrite dependent denitrification where 18 and 52 nmol N2O h-1 gDW-1, respectively. N2O was below 30% of total produced N gases in fen soil when concentrations of nitrate and nitrite were N2O consumption was up to 36 nmol N2O h-1 gDW-1. Denitrifier diversity was assessed by analyses of narG, nirK/nirS, and nosZ (encoding nitrate-, nitrite-, and nitrous oxide reductases, respectively) by barcoded amplicon pyrosequencing. Analyses of ~14,000 quality filtered sequences indicated up to 25 species-level operational taxonomic units (OTUs), and up to 359 OTUs at 97% sequence similarity, suggesting diverse denitrifiers. Phylogenetic analyses revealed clusters distantly related to publicly available sequences, suggesting hitherto unknown denitrifiers. Representatives of species-level OTUs were affiliated with sequences of unknown soil bacteria and Actinobacterial, Alpha-, Beta-, Gamma-, and Delta-Proteobacterial sequences. Comparison of the 4 gene markers at 97% similarity indicated a higher diversity of narG than for the other gene markers based on Shannon indices and observed number of OTUs. The collective data indicate (i) a high denitrification and N2O consumption potential, and (ii) a highly diverse, nitrate limited denitrifier

  10. Denitrification activity of a remarkably diverse fen denitrifier community in finnish lapland is N-oxide limited.

    Directory of Open Access Journals (Sweden)

    Katharina Palmer

    Full Text Available Peatlands cover more than 30% of the Finnish land area and impact N2O fluxes. Denitrifiers release N2O as an intermediate or end product. In situ N2O emissions of a near pH neutral pristine fen soil in Finnish Lapland were marginal during gas chamber measurements. However, nitrate and ammonium fertilization significantly stimulated in situ N2O emissions. Stimulation with nitrate was stronger than with ammonium. N2O was produced and subsequently consumed in gas chambers. In unsupplemented anoxic microcosms, fen soil produced N2O only when acetylene was added to block nitrous oxide reductase, suggesting complete denitrification. Nitrate and nitrite stimulated denitrification in fen soil, and maximal reaction velocities (vmax of nitrate or nitrite dependent denitrification where 18 and 52 nmol N2O h-1 gDW-1, respectively. N2O was below 30% of total produced N gases in fen soil when concentrations of nitrate and nitrite were <500 μM. vmax for N2O consumption was up to 36 nmol N2O h-1 gDW-1. Denitrifier diversity was assessed by analyses of narG, nirK/nirS, and nosZ (encoding nitrate-, nitrite-, and nitrous oxide reductases, respectively by barcoded amplicon pyrosequencing. Analyses of ~14,000 quality filtered sequences indicated up to 25 species-level operational taxonomic units (OTUs, and up to 359 OTUs at 97% sequence similarity, suggesting diverse denitrifiers. Phylogenetic analyses revealed clusters distantly related to publicly available sequences, suggesting hitherto unknown denitrifiers. Representatives of species-level OTUs were affiliated with sequences of unknown soil bacteria and Actinobacterial, Alpha-, Beta-, Gamma-, and Delta-Proteobacterial sequences. Comparison of the 4 gene markers at 97% similarity indicated a higher diversity of narG than for the other gene markers based on Shannon indices and observed number of OTUs. The collective data indicate (i a high denitrification and N2O consumption potential, and (ii a highly diverse

  11. Rich fen development in SE Poland and its response to climate changes and human impacts in the late Holocene

    Science.gov (United States)

    Gałka, Mariusz; Apolinarska, Karina; Aunina, Liene; Feurdean, Angelica; Hutchinson, Simon; Kołaczek, Piotr

    2016-04-01

    Rich fens are one of the most important wetland ecosystems due to their high species-richness and unique species composition. They are occupied by endangered, vulnerable and protected plants, such as Cladium mariscus and Schoenus ferrugineus. For this reason knowledge of the history of rich fens is important for the development of effective management strategies to protect or restore these widely threatened habitats. Our palaeoecological study reconstructs the development of Bagno Serebryskie rich fen (ca. 376 ha), a site with the largest population of Cladium mariscus in CE Europe, and its response to climate changes and human impacts during the last 3500 years. For this we analyse two peat profiles at this site, at a high resolution (1 and 2 cm) using multi-aspect palaeoecological analyses (plant macrofossils, pollen, molluscs, geochemistry, charcoal and AMS 14C radiocarbon) to assess the impact of climate changes, human activity, and fires on local vegetation. Local plant succession in our two coring points followed parallel trajectories; after a lake stage, ca. 1800 cal yr BP (core I) and 3300 cal yr BP (core II), fen species e.g. Menyanthes trifoliata, Mentha aquatic, Carex lasiocarpa appeared, followed at ca. 500 cal. yr BP by Cladium mariscus, which is currently the dominant plant species in the Bagno Serebryskie peatland. In one peat profile (core II) we found abundant macrocharcoal particles at 1050, 700, 400 cal yr BP and the present, but fires had no significant impact on the development of the mire. In the other peat profile (core I) we noted four stages (at 2300, 1350, 400, 100 cal yr BP) with an increasing diversity of mollusc species typical of overgrown, but permanent water bodies. Their increased abundance and diversity can be linked to a rise in mire water table at these times. Our studies indicate that rich fens can provide reliable sites for palaeoecological reconstruction of the late Holocene providing valuable information that can be applied

  12. How a regional aquifer, a local aquifer and an oxbow lake impact on hydrological and biogeochemical processes in ariparian fen-meadow ecosystem

    OpenAIRE

    Hoffmann, Carl Christian; Pedersen, Morten Lauge; Rasmussen, K R

    2009-01-01

    The groundwater flow pattern through a riparian fen-meadow was investigated by use of piezometer transects, soil survey, measurements of piezometric heads and measurements of hydraulic conductivity. Groundwater was sampled from piezometers and analysed for nitrate-N. Water balances and nitrate-N mass balances were calculated. The groundwater flow pattern through a riparian fen-meadow was investigated by use of piezometer transects, soil survey, measurements of piezometric heads and measure...

  13. Análisis comparativo de compuestos fenólicos totales y actividad antioxidante de cuatro marcas de tisanas de Hibiscus sabdariffa (Malvaceae) comercializadas en Costa Rica

    OpenAIRE

    Melissa Agüero; Cindy Segura; Jonathan Parra

    2014-01-01

    Las tisanas de rosa de Jamaica (Hibiscus sabdariffa) son consumidas en Costa Rica por su conocido efecto cardioprotector asociado a la presencia de compuestos fenólicos, principalmente antocianinas. Este trabajo estableció diferencias en el perfil de compuestos fenólicos y su actividad anti-radical entre diferentes comercializadores de tisanas de Hibiscus sabdariffa en Costa Rica. Se identificaron cualitativamente taninos, flavonoides y antocianinas. Se cuantificó la cantidad total de compues...

  14. The use of the stable isotope, oxygen-18, as a tracer to measure gross primary production in coastal and oligotrophic waters and in monoclonal cultures of marine phytoplankton

    Energy Technology Data Exchange (ETDEWEB)

    Grande, K.D.

    1988-01-01

    A new technique was developed to measure the in vitro rates of gross oxygen production in planktonic communities, in which water is enriched with the stable isotope {sup 18}O, and photosynthetic evolution of {sup 18}O{sup 16}O is measured. In order to calculate gross oxygen production, they correct for the {sup 18}O fractionation due to respiration. The standard technique for measuring production in the oceans, {sup 14}C-bicarbonate uptake, has recently been questioned due to discrepancies with other estimates of water column production and suspected intrinsic problems with the {sup 14}C technique. They compared rates of {sup 18}O gross production and {sup 14}C production in oligotrophic and coastal sites. Samples were generally incubated under natural lighting with neutral density screening. Some oligotrophic bottles were incubated in situ at the depth of collection. Rates of {sup 14}C production were 60-100% of {sup 18}O gross production in both coastal and oceanic communities. Assuming a PQ of 1.0 to 1.5, these comparisons suggest that {sup 14}C production rates are not seriously underestimating actual in vitro rates of production. They also measured rates of light respiration in cultures and natural populations by the {sup 18}O technique. The rates of light respiration in algal cultures were generally greater than dark rates by a factor of two to ten. The increased respiration in the light could be due to increased rates of mitochondrial respiration, photorespiration or Mehler respiration. They measured the enhanced {sup 14}C production under reduced (O{sub 2}) conditions (the Warburg effect), as an estimate of the rate of photorespiration. In three clones, rates of photorespiration were a significant fraction of light respiration. In five other clones examined, photorespiration was not implicated as a source of light respiration.

  15. The influence of nanoflagellates on the spatial variety of picoplankton and the carbon flow of the microbial food web in the oligotrophic subtropical pelagic continental shelf ecosystem

    Science.gov (United States)

    Chiang, Kuo-Ping; Tsai, An-Yi; Tsai, Pei-Jung; Gong, Gwo-Ching; Huang, Bang-Qin; Tsai, Sheng-Fang

    2014-06-01

    To investigate the mechanism of the spatial dynamics of picoplankton community (bacteria and Synechococcus spp.) and to estimate the carbon flux of the microbial food web in the oligotrophic Taiwan Warm Current Water of the subtropical marine pelagic ecosystem, we conducted size-fractionation experiments during five cruises by the R/V Ocean Research II during the summers of 2010 and 2011 in the southern East China Sea. We carried out culture experiments using surface water, which according to a temperature-salinity (T-S) diagram, is characterized as oligotrophic Taiwan Current Warm Water. We found a negative correlation between bacteria growth rate and temperature, and another negative correlation between nitrate and temperature indicating that the active growth of heterotrophic bacteria might be induced by nutrients lifted from a deep layer by cold upwelling water. This finding suggests that the area we studied was a bottom-up control pelagic ecosystem. Upwelling brings nutrient-rich water to the euphotic zone and promotes bacterial growth, resulting in increased picoplankton biomass, which increases the consumption rate of nanoflagellates. The net growth rate (growth rate-grazing rate) becomes negative when the densities of bacteria and Synechococcus spp. are lower than the threshold values. The interaction between growth and grazing will limit the abundance of bacteria (105-106 cells ml-1) and Synechococcus spp. (104-105 cells ml-1) within a narrow range. Meanwhile, 61% of bacteria production and 54% of Synechococcus spp. production are transported to a higher trophic level (nanoflagellate), though the cascade effect might cause an underestimation of both percentages of transported carbon. Based on the successive size-fractionation experiments, we estimated that the predation values were underestimated and that the diet of nanoflagellates is composed of 64% bacteria and 36% Synechococcus spp.

  16. Análisis comparativo de compuestos fenólicos totales y actividad antioxidante de cuatro marcas de tisanas de Hibiscus sabdariffa (Malvaceae comercializadas en Costa Rica

    Directory of Open Access Journals (Sweden)

    Melissa Agüero

    2014-01-01

    Full Text Available Las tisanas de rosa de Jamaica (Hibiscus sabdariffa son consumidas en Costa Rica por su conocido efecto cardioprotector asociado a la presencia de compuestos fenólicos, principalmente antocianinas. Este trabajo estableció diferencias en el perfil de compuestos fenólicos y su actividad anti-radical entre diferentes comercializadores de tisanas de Hibiscus sabdariffa en Costa Rica. Se identificaron cualitativamente taninos, flavonoides y antocianinas. Se cuantificó la cantidad total de compuestos fenólicos por el método de Folin-Ciocalteu y se cuantificó la actividad antioxidante con el método de DPPH. Todas las marcas comerciales demostraron presencia de compuestos fenólicos, incluyendo antocianinas; sin embargo, se encontraron diferencias significativas en el contenido de compuestos fenólicos y actividad anti-radical, entre los diferentes productores de tisanas. Por ello, se concluye que en el mercado costarricense, el perfil en compuestos fenólicos de las tisanas en estudio varía de acuerdo con el productor.

  17. Una mirada al fenómeno de la violencia escolar en Costa Rica

    Directory of Open Access Journals (Sweden)

    Leonel Arias Sandoval

    2009-06-01

    Full Text Available

    Recibido 30 de julio de 2008 • Aprobado 23 de marzo de 2009 • Corregido 20 de abril de 2009

     

    Resumen. En el actual contexto educativo, padres de familia, estudiantes, docentes, medios de comunicación y demás sectores de la sociedad costarricense, manifiestan su preocupación ante el problema de la violencia escolar, fenómeno social que ha venido en aumento en los últimos años. Sus manifestaciones se perciben por medio de conductas de maltrato, intimidación, agresión verbal o física entre jóvenes, y que se construye por medio de prácticas culturales. De ahí que, para comprender este problema, se debe reflexionar acerca de las posibles causas, teniendo en cuenta el contexto en el cual se desarrolla la convivencia social en cada centro educativo. Algunas de las manifestaciones de violencia tienen su origen en la familia, en la comunidad, en la imitación de patrones de conducta y en la influencia de los medios de información de masa. Además, estos comportamientos son potenciados por el modelo curricular vigente, lo que genera resistencia a las normas institucionales.

     

    Abstract. In the current context of education, parents, students, teachers, media and other sectors of Costa Rican society, express concern about the problem of school violence, a social phenomenon that has been increasing in recent years. Its manifestations are perceived by means of abuse behavior, intimidation, verbal or physical abuse among youth, which are constructed through cultural practices. Therefore, to understand this problem, reflection about possible causes is in order, taking into account the context in

  18. Hipertemia durante el fenómeno de el niño, 1997-98

    Directory of Open Access Journals (Sweden)

    Jaime Miranda M

    2003-10-01

    Full Text Available Objetivo: Describir el cuadro clínico y la evolución de los casos de síndrome febril presentados durante el fenómeno de "El Niño" de 1997-98, y presentar una revisión de la fisiopatología del cuadro de hipertermia. Material y métodos: Se realizó un estudio descriptivo longitudinal en la ciudad de Chimbote, Ancash. Se definió como caso de síndrome febril: niños menores de 5 años con fiebre refractaria al uso de antipiréticos sin foco aparente de infección. En el análisis posterior se consideraron: apariencia no tóxica, previamente sano, sin foco de infección al examen físico y con examen de laboratorio negativo. Resultados: Fueron estudiados 25 casos (68% varones, 80% con edades entre 5 y 18 meses con un tiempo de enfermedad promedio de 15,17(13,52 días ± desviación stándar (±DS. La mediana de la temperatura fue 38,8ºC con un promedio de 38,84ºC (rango 38 - 40ºC. 68% tuvo un tiempo de enfermedad mayor de 15 días; 52% había visitado al menos una vez un centro médico anterior; 68% recibió antibióticos y antipiréticos; y, 52 % ingresó al hospital por emergencia. Todos los casos presentaron alza térmica, asociado a piel seca (72%, diarrea (64%, tos (52%, baja de peso (52%, irritabilidad (44%, náuseas o vómitos (40%, rinorrea (24% y convulsiones (20%. El tiempo de hospitalización promedio fue 4,7 días y el estado febril promedio fue 2,5 días. Ninguno tuvo examen de laboratorio compatible con causa infecciosa. Conclusiones: En situaciones ambientales adversas debe considerarse al calor ambiental como un factor importante en el desarrollo de la hipertermia, con el propósito de brindar un manejo más apropiado a los afectados en el menor tiempo posible.

  19. Modeling ecohydrological controls on net CO2 exchange of a boreal fen

    Science.gov (United States)

    Grant, R.; Mezbahuddin, S.; Flanagan, L.

    2012-04-01

    Hydrology is one of the key controls governing peatland carbon balance under current and future climatic conditions. Seasonal variations in soil water content and water table depths can alter the balance between peatland primary production and respiration and so cause a peatland to change between a sink and a source of carbon. Seasonal and interannual variation in peat hydrology can affect primary production and respiration through its influence on evapotranspiration, plant water and nutrient uptake and on microbial decomposition. Simulating ecohydrological controls on current and future net ecosystem productivity (NEP) of peatlands thus demands models with coupled soil-plant-atmosphere schemes for gases, water, energy, carbon and nutrients (N, P). We combined a 3-dimensional water transport scheme and prognostic water table dynamics with an existing ecosystem model ecosys in order to examine the hydrological controls on seasonal and interannual variability in NEP of a rich fen in Alberta, Canada. Simulated hourly ecosystem energy and CO2 fluxes along with hourly near surface soil water contents and daily water table depths correlated very well (R2 ~ 0.80) with measurements at the site from 2003 to 2009, during which the water table declined gradually. We compared modeled and measured fluxes at hourly and seasonal time scales in years with contrasting weather and water table depths in order to see how water table fluctuations altered the diurnal and seasonal patterns of NEP. In the model, shallow water tables limited root and soil aeration, slowing root and microbial growth, and hence nutrient uptake. This reduced gross primary productivity (GPP) but also ecosystem respiration (RE), so that the peatland remained a substantial net C sink. In the model, deeper water tables caused more rapid microbial and root growth, and hence more rapid mineralization and nutrient uptake, and hence greater GPP. Deeper water tables also caused near-surface drying which slightly

  20. Boko Haram: análisis del fenómeno terrorista en Nigeria

    Directory of Open Access Journals (Sweden)

    Francisco Javier Torregrosa López

    2016-04-01

    Full Text Available El terrorismo sufre cambios en la actualidad y evoluciona a la par que el resto del mundo. Boko Haram supone el ejemplo perfecto de un nuevo terrorismo emergente, alimentado por la globalización y la economía, pero fundamentado a su vez en pilares tan antiguos como el fanatismo religioso y los conflictos interculturales. En este artículo se trata de revisar las claves del nacimiento y desarrollo de este grupo terrorista: las características de su país de origen, los elementos que llevaron al surgimiento de este grupo terrorista, qué estrategias de asalto y financiación utiliza en la actualidad y cómo lleva a cabo Boko Haram: análisis del fenómeno terrorista en Nigeria Rafael López Pérez Doctor en Psicología. Presidente de la Fundación Universitaria Behavior & Law, Madrid, España. rlopez@behaviorandlaw.com Nahikari Sánchez Herrero Magíster en Seguridad. Especialidad en perfiles terroristas. Profesora de Crímina, Centro para el estudio y prevención de la delincuencia, Pamplona, España. nahikari.sanchez@crimina.es Ángel García Collantes Doctor en Derecho. Director de la Cátedra de Análisis de Conducta UDIMA - Fundación Universitaria Behavior & Law, Madrid, España. angel.garcia.c@udima.es Francisco Javier Torregrosa López Magíster en Criminología y Ciencias Forenses. Investigador en la Fundación Universitaria Behavior & Law, Alicante, España. javiertorregrosalopez@behaviorandlaw.com David Garriga Guitart Magíster en Mundo Árabe e Islámico. Analista de Terrorismo Yihadista, Fundación Universitaria Behavior & Law, Barcelona, España. dgarriga@behaviorandlaw.com su reclutamiento, así como su relación con otros grupos terroristas. Por último, con base en la teoría analizada, se realizará un análisis prospectivo sobre qué dirección es más probable que sigan sus acciones durante un futuro inmediato y a largo plazo. Las conclusiones alcanzadas por los autores indican que Boko Haram con probabilidad continuar

  1. Component analysis and quantitative structure-retention relationship study of aroma compounds in fen liquor%汾酒香味成分分析及定量结构-色谱保留相关研究

    Institute of Scientific and Technical Information of China (English)

    乔华; 李美萍; 马艳红; 费珊珊; 张生万

    2012-01-01

    以清香型汾酒为研究对象,采用气相色谱/质谱联用方法,分析了汾酒中的主要香味成分,利用btericandE1。ctronicDescriptors(SEDs)建立了预测香味成分的定量结构一色谱保留相关模型,发现汾酒中主要香味成分酯、醇、酸、醚、烃、醛、酮的保留时间分别与不同的SEDs参数有良好的相关性,建模相关系数分别为酯R=0.991、醇R=O.995、酸R=0.995、醚和烃R=0.995、醛酮R=0.969,留-法交互检验(Leave-one-out,Loo)相关系数分别为酯RLoo=0.986、醇R。=0.986、酸RLoo=0.991、醚和烃RLoo=0.944、醛酮RLoo=0.932。结果表明,所建模型具有良好的稳定性和预测能力.为白酒中香味成分的分离检测提供了有效的理论依据。%Fen liquor was selected as the objective and its aroma components were studied by gas chromatography/mass spectrometry. To predict the retention times of aroma components in Fen liquor, the quantitative structure-retention relationship models were generated by using Steric and Electronic Descriptors (SEDs).It was found that retention times of the aroma components in Fen liquor had good relationships with different selected SEDs parameters.The correlation coefficients(R)for the built models were. esters R = 0.991, alcohols R =0.995,acids R = 0.995, ethers and hydrocarbons R = 0.995, aldehydes and ketones R = 0.969, and the leave- one- out ( LOO ) cross- validation coefficients ( RLoo ) were: esters RLoo = 0.986, alcohols RLoo = 0.986, acids RLoo =0.991,ethers and hydrocarbons RLoo = 0.944, aldehydes and ketones RLoo = 0.932.Results showed that the models were of good stability and predictability, and they were useful to develop methods for identifying and separating aroma components in Chinese liquor.

  2. Microbial reduction of iron and porewater biogeochemistry in acidic peatlands

    Directory of Open Access Journals (Sweden)

    K. Küsel

    2008-11-01

    Full Text Available Temporal drying of upper soil layers of acidic methanogenic peatlands might divert the flow of reductants from CH4 formation to other electron-accepting processes due to a renewal of alternative electron acceptors. In this study, we evaluated the in situ relevance of Fe(III-reducing microbial activities in peatlands of a forested catchment that differed in their hydrology. Intermittent seeps reduced sequentially nitrate, Fe(III, and sulfate during periods of water saturation. Due to the acidic soil conditions, released Fe(II was transported with the groundwater flow and accumulated as Fe(III in upper soil layers of a lowland fen apparently due to oxidation. Microbial Fe(III reduction in the upper soil layer accounted for 26.7 and 71.6% of the anaerobic organic carbon mineralization in the intermittent seep and the lowland fen, respectively. In an upland fen not receiving exogenous Fe, Fe(III reduction contributed only to 6.7%. Fe(II and acetate accumulated in deeper porewater of the lowland fen with maximum concentrations of 7 and 3 mM, respectively. Both supplemental glucose and acetate stimulated the reduction of Fe(III indicating that fermentative, incomplete, and complete oxidizers were involved in Fe(II formation in the acidic fen. Amplification of DNA yielded PCR products specific for Acidiphilium-, Geobacter-, and Geothrix-, but not for Shewanella- or Anaeroromyxobacter-related sequences. Porewater biogeochemistry observed during a 3-year-period suggests that increased drought periods and subsequent intensive rainfalls due to global climate change will further favor Fe(III and sulfate as alternative electron acceptors due to the storage and enhanced re-oxidation of their reduced compounds in the soil.

  3. Microbial reduction of iron and porewater biogeochemistry in acidic peatlands

    Directory of Open Access Journals (Sweden)

    K. Küsel

    2008-05-01

    Full Text Available Temporal drying of upper soil layers of acidic methanogenic peatlands might divert the flow of reductants from CH4 formation to other electron-accepting processes due to a renewal of alternative electron acceptors. In this study, we evaluated the in situ relevance of Fe(III-reducing microbial activities in peatlands of a forested catchment that differed in their hydrology. Intermittent seeps reduced sequentially nitrate, Fe(III, and sulfate during periods of water saturation. Due to the acidic soil conditions, released Fe(II was transported with the groundwater flow and accumulated as Fe(III in upper soil layers of a lowland fen apparently due to oxidation. Microbial Fe(III reduction in the upper soil layer accounted for 26.7 and 71.6% of the anaerobic organic carbon mineralization in the intermittent seep and the lowland fen, respectively. In an upland fen not receiving exogenous Fe, Fe(III reduction contributed only to 6.7%. Fe(II and acetate accumulated in deeper porewater of the lowland fen with maximum concentrations of 7 and 3 mM, respectively. Both supplemental glucose and acetate stimulated the reduction of Fe(III indicating that fermentative, incomplete, and complete oxidizers were involved in Fe(II formation in the acidic fen. Amplification of DNA yielded PCR products specific for Acidiphilium-, Geobacter-, and Geothrix-, but not for Shewanella- or Anaeroromyxobacter-related sequences. Porewater biogeochemistry observed during a 3-year-period suggests that increased drought periods and subsequent intensive rainfalls due to global climate change will further favor Fe(III and sulfate as alternative electron acceptors due to the storage of their reduced compounds in the soil.

  4. Examination of mercury and organic carbon dynamics from a constructed fen in the Athabasca oil sands region, Alberta, Canada using in situ and laboratory fluorescence measurements

    Science.gov (United States)

    Oswald, C.; Carey, S. K.

    2013-12-01

    In the Athabasca oil sands region, mined landscapes must be reclaimed to a functioning natural ecosystem as part of the mine closure process. To test wetland construction techniques on oil sands tailings, 55 ha of mined landscape on the Syncrude Canada Ltd. property is being reclaimed to a watershed containing a graminoid fen. The 18 ha constructed fen consists of an approximately 50 cm thick peat-mineral soil layer separated from underlying tailings sand by a thin layer of clay till. The water table in the fen is maintained by pumping water into the fen from a nearby lake and controlling outflow with under-drains. The objective of this study was to assess total mercury (THg) and methyl mercury (MeHg) concentration dynamics in water exported from the fen in relation to organic carbon quantity and composition. Water quality data from summer 2012 when the fen pumps were first turned on show that dissolved organic carbon (DOC) concentrations are on average twice as high in water flowing through the underlying tailings sand aquifer (median: 42.0 mg/L) compared to DOC concentrations in water flowing through the fen peat package (median: 20.3 mg/L). Given these DOC concentrations, filtered THg concentrations are very low (median values are 0.81 ng/L and 0.17 ng/L for water flowing through the fen peat and sand tailings, respectively) compared to concentrations reported for other boreal wetlands. Although a relationship was identified between filtered THg and DOC (r2=0.60), its slope (0.06 ng Hg/mg C) is an order-of-magnitude smaller than the typical range of slopes found at other wetland sites potentially suggesting a small pool of mercury in the peat and/or limited partitioning of mercury into solution. Filtered MeHg concentrations in all water samples are near the limit of detection and suggest that biogeochemical conditions conducive to methylation did not exist in the fen peat or tailings sand at the time of sampling. In addition to these baseline THg and Me

  5. Violência como fenômeno intrínseco à cultura política brasileira

    Directory of Open Access Journals (Sweden)

    Antonio M. Soares

    2016-06-01

    Full Text Available Este artigo problematiza o conceito de violência e suas mutações através dos tempos. Como fenômeno cultural, a violência é construída na sociedade e se processa de forma a romper com os próprios códigos de ordens produzidos por ela. No caso do Brasil a violência se mostra intrínseca ao processo de formação da sociedade brasileira, estando presente nas lógicas autoritárias e na imposição cultural desde os tempos da colonização. A violência emerge como uma agressão ao indivíduo e ao coletivo, ela aniquila o sentido da política e desabilita o mundo comum. As interpretações presentes neste trabalho buscam aprofundar as análises sobre a violência enquanto fenômeno social e cultural, redimensionando os efeitos que ela produz para a condição humana e suas associações com as dimensões da civilidade, incivilidade e descivilidade. Neste contexto, destacaremos como o fenômeno da violência se afirmou como uma dimensão estrutural e cultural da formação da sociedade brasileira, como ele se revela na contemporaneidade, nos jogos de poder, nas relações de força e no movimento de fronteiras tênues entre o legal e o ilegal.

  6. Sentimentos do adolescente relacionados ao fenômeno BULLYING: possibilidades para a Assistência de Enfermagem nesse contexto

    OpenAIRE

    Agnes Schutz de Oliveira; Priscila da Silva Antonio

    2006-01-01

    O bullying é um fenômeno devastador podendo vir a afetar a auto-estima e a saúde mental dos adolescentes. Geralmente ocorre quando o adolescente é mais suscetível ou vulnerável às agressões verbais ou morais que lhes causam angústia e dor, principalmente quando ocorrido em ambiente escolar traduzindo-se como uma forma de exclusão social. Pode desencadear alguns problemas de saúde tais como a anorexia, bulimia, depressão, ansiedade e até mesmo o suicídio. A enfermagem, pautada com princípios d...

  7. Datos, fenómenos y representación: Sobre el estructuralismo empirista de van Fraassen

    Directory of Open Access Journals (Sweden)

    José Luis Rolleri

    2015-01-01

    Full Text Available Se analizan ciertos conceptos del estructuralismo empirista de Bas van Fraassen, en particular, el de representación, para intentar una crítica a su posición con respecto al vínculo entre los modelos de las teorías y, en última instancia, el mundo físico por medio de los modelos de datos, a los cuales van Fraassen les adjudica el papel de representantes de los fenómenos. Al final se delinea, a muy grandes rasgos, una alternativa conceptualista.

  8. CO2 exchange of a sedge fen in southern Finland—the impact of a drought period

    OpenAIRE

    Aurela, Mika; Riutta, Terhi; Laurila, Tuomas; Tuovinen, Juha-Pekka; Vesala , Timo; Tuittila, Eeva-Stiina; Rinne, Janne; Haapanala, Sami; Laine, Jukka

    2011-01-01

    Eddy covariance (EC) measurements of net ecosystem CO2 exchange (NEE) were conducted on a boreal sedge fen in southern Finland (61°50′N, 24°12′E) during a 1.5-yr period covering two summers in 2004–2005. The EC data were complemented by chamber measurements, which enabled the partition of the daytime NEE into respiration and photosynthesis. A special emphasis was put on the hydrometeorological responses of CO2 exchange during a drought period in July 2005. A mean CO2 efflux of 0.009 mgCO2 m-2...

  9. Estudio del fenómeno Social Media en la media empresa del sector TIC español

    OpenAIRE

    Muñoz Fernández, Víctor

    2014-01-01

    Con el paso de los años, el fenómeno Social Media ha adquirido una mayor importancia entre las empresas, gracias a las posibilidades que les ofrece. Este proyecto está basado en: - En primer lugar, elaborar un estudio teórico con el que se pretende entender el empleo que hace la empresa en general de la Web 2.0. - En segundo lugar, elaborar un estudio práctico con el que se pretende conocer el uso y consecuencias que están logrando las medianas empresas del sector TIC español, gracia...

  10. El abstencionismo como fenómeno político en la sociedad contemporánea

    Directory of Open Access Journals (Sweden)

    Rogelio López Sánchez

    2013-01-01

    Full Text Available El objetivo de la presente contribución es analizar el abstencionismo como fenómeno político. En este sentido, se examinan las distintas facetas del mismo con la finalidad de acercarnos hacia un modelo de participación cívica racional en el contexto mexicano. Igualmente, se lleva a cabo una crítica en contra del monopolio partidista que deja a los ciudadanos un pequeño margen de cuestiones políticas en las cuales puedan tomar parte.

  11. Denitrification Activity of a Remarkably Diverse Fen Denitrifier Community in Finnish Lapland Is N-Oxide Limited

    OpenAIRE

    Palmer, Katharina; Horn, Marcus A.

    2015-01-01

    Peatlands cover more than 30% of the Finnish land area and impact N2O fluxes. Denitrifiers release N2O as an intermediate or end product. In situ N2O emissions of a near pH neutral pristine fen soil in Finnish Lapland were marginal during gas chamber measurements. However, nitrate and ammonium fertilization significantly stimulated in situ N2O emissions. Stimulation with nitrate was stronger than with ammonium. N2O was produced and subsequently consumed in gas chambers. In unsupplemented anox...

  12. Influência dos compostos fenólicos de especiarias sobre a lipoperoxidação e o perfil lipídico de tecidos de ratos Influence of spices phenolic compounds on lipoperoxidation and lipid profile of rats tissues

    Directory of Open Access Journals (Sweden)

    Ana Vládia Bandeira Moreira

    2004-12-01

    Full Text Available OBJETIVO: Este trabalho avaliou o efeito antioxidante dos compostos fenólicos de uma mistura de especiarias (mostarda, canela e erva-doce sobre o metabolismo dos ácidos graxos das séries ômega3 e ômega6. MÉTODOS: Ratos Wistar recém desmamados receberam dieta rica em gorduras essenciais e um chá de especiarias. Após 45 dias, os animais foram sacrificados e tiveram seus tecidos coletados para análise das substâncias reativas ao ácido tiobarbitúrico e perfil lipídico. RESULTADOS: O chá fornecido aos animais apresentou atividade antioxidante equivalente ao hidroxitolueno butilado. Foram identificados no chá, os ácidos fenólicos catecol, salicílico e caféico; as enzimas cicloxigenase e lipoxigenase foram inibidas pelos extratos ricos nestes ácidos fenólicos. O perfil de ácidos graxos apresenta diferença entre os grupos teste e controles. Todos os tecidos dos grupos teste apresentaram menores valores em lipoperoxidação, em comparação aos controles. CONCLUSÃO: Estes dados sugerem, portanto, um efeito antioxidante das substâncias fenólicas identificadas na mistura das especiarias, sobre os ácidos graxos das séries ômega3 e ômega6.OBJECTIVE: This work analyzed the influence of the phenolic compounds from a blend of spices (mustard, cinnamon and anise on the omega3 and omega6 fatty acids metabolism. METHODS: Weaned Wistar rats received a diet rich in essencial lipids and an infusion of blended spices for 45 days. After that period, they were sacrificed their tissues were collected and analized for the TBARS and lipid profile by CGMS. RESULTS: The tea of spices showed an antioxidant activity equivalent to that of the butylated hydroxytoluene. The following phenolic acids were identified in the infusion, using mass chromatography: cathecol, salicilic and cafeic; Lipooxygenase and ciclooxigenase enzymes were inhbited by the phenolic acid extracts. It was observed that the total amount of the fatty acids found in the test

  13. Metódica: Articulación sistema teórico, fenómeno y procesos en el objeto de estudio. Una perspectiva desde el fenómeno pobreza

    Directory of Open Access Journals (Sweden)

    Yajaira Jiménez Zabala

    2011-10-01

    Full Text Available En este artículo discutimos la visión metódica que toma como apoyo el pivote entre lo cualitativo, lo cuantitativo y el orden de complejidad, en un enfoque plurimetódico, a través del cual se construyó la visión de la pobreza como objeto de estudio. Tal selección, está justificada en tanto se entiende la pobreza como un fenómeno social complejo, por las diversas aristas que le identifican. La combinación de los enfoques metodológicos permitió la aprehensión de los diferentes aspectos del fenómeno y de sus interrelaciones en las representaciones de los actores sociales vinculados con el estudio. Lo cualitativo, se entiende como la simbiosis de prácticas interpretativas, que no privilegia una metodología sobre otra. Lo cuantitativo estuvo referido al uso de indicadores derivados de los soportes referenciales del problema; el orden de complejidad, atendió a la manifestación de lo simple en tanto nodo tensional complejo, que requiere una mirada diferente para su comprensión e interpretación.

  14. THE CHEMICAL COMPOSITION OF TYPICAL PEAT-FORMING PLANTS LIPIDS OF WEST SIBERIA FOREST ZONE OLIGOTROPHIC BOGS

    Directory of Open Access Journals (Sweden)

    Ольга Викторовна Серебренникова

    2014-09-01

    Full Text Available The paper describes the molecular composition and distribution of hydrocarbons and oxygen-containing compounds in the main bog peat-forming plants – scheuchzeria, sedge, cotton grass and sphagnum moss. It is shown that all plants contain n-alkanes, arenes, sesquiterpenes, fatty acids, esters, aldehydes, alcohols and ketones. The most representative group of hydrocarbons (HC in all bog plants are n-alkanes. Arenas are presented by bi-, tri- and tetracyclic structures. Ketones include acyclic compounds with normal and isoprenoid structure and alicyclic compounds with two, four and five cycles. Alcohols are presented by aliphatic and monoaromatic structures, aldehydes, fatty acids and esters – by compounds with acyclic structure. Tetra- and pentacyclic oxygen-containing substances includes steroid and triterpenoid alcohols and ketones.

  15. El fenómeno del acoso laboral entre los trabajadores de la universidad O fenômeno mobbing entre os trabalhadores da universidade The phenomenon of mobbing among university employees

    Directory of Open Access Journals (Sweden)

    Fernando Justicia Justicia

    2007-12-01

    Full Text Available El objetivo del artículo es realizar una descripción del fenómemo mobbing -acoso laboral- en el contexto de la universidad. Los trabajos realizadossobre este problema no son muy prolíficos lo que puede explicar la gran dificultad para caracterizar el fenómeno en el ámbito universitario. En el presente trabajo presentamos los niveles de incidencia del acoso laboral entre la población universitaria, los tipos de acoso más frecuentes y los efectos producidos en las víctimas, con la finalidad de caracterizar y definir el problema. Al mismo tiempo, intentamos conocer la influencia de determinadas variables como la edad, género y tiempo de victimización. En este sentido, y de acuerdo con otros estudios realizados, encontramos diferencias estadísticas en función del género de las víctimas. Del mismo modo, los resultados apuntan que la frecuencia y duración del acoso laboral afectan negativamente a las víctimas provocando un empeoramiento de los efectos derivados del acoso.O objetivo deste artigo é realizar uma descrição do fenômeno mobbing -tormento e persecução no lugar do trabalho- no contexto da universidade. Há poucos trabalhos realizados sob este problema nos contextos de educação superior o que pode explicar a grande dificuldade para caracterizar o fenômeno no âmbito universitário. Neste artigo apresentamos os níveis de incidência entre a população universitária, os tipos de mobbing mais freqüentes e os efeitos produzidos nas vítimas com a finalidade de caracterizar e definir o problema. Ao mesmo tempo, tentamos conhecer a influência de determinadas variáveis tais como a idade, gênero ou o tempo de exposição ao fenômeno. Neste sentido, e em concordância com outros estudos realizados, encontramos diferenças estatísticas em função do gênero das vítimas. De igual forma, os dados apontam que a freqüência e duração da situação de persecução no trabalho afetam negativamente as vítimas provocando

  16. Comparison of phenol content and antioxidant capacity of nuts Comparação entre o conteúdo de fenólicos e capacidade antioxidante de sementes

    Directory of Open Access Journals (Sweden)

    Lucile Tiemi Abe

    2010-05-01

    Full Text Available Frequent nut intake is associated with protective effects against cardiovascular diseases. In addition to the generally high contents of unsaturated fatty acids, polyphenol compounds seem to be also implicated in health promoting effects of nuts due to their antioxidant properties. In this way, eleven different kinds of nuts, including pinhao seeds (Araucaria angustifolia and Brazil nuts (Bertholletia excelsa, typical of Brazil, were analyzed for the content of phenol compounds, including the potent anti-mutagenic and anti-cancer ellagic acid, and antioxidant capacity of methanolic extracts. The antioxidant capacity varied a hundred times among the different nuts, from 1.2 to 120 mg of Trolox equivalents.100 g-1 (FW. Total ellagic acid was determined after acid hydrolysis of ellagitannins and ellagic acid glycosides, and it was detected in only 3 of the 11 samples. The content of free and total ellagic acid in nuts varied from 0.37 to 41 and from 149 (chestnuts to 823 (walnuts mg.100 g-1 (FW, respectively. Among nuts, samples with the highest contents of ellagic acid (walnuts and pecans also presented the highest total phenol contents and DPPH radical scavenging capacities. Pinhao seeds and Brazil nuts did not present significant amounts of phenols nor antioxidant capacity.O consumo frequente de nozes está associado a efeitos protetores contra doenças cardiovasculares. Além do alto teor de ácidos graxos insaturados, os compostos polifenólicos também parecem implicados nos efeitos promotores da saúde devido a suas propriedades antioxidantes. Desta forma, onze tipos de nozes/sementes, incluindo pinhão (Araucaria angustifolia e castanha-do-pará (Bertholletia excelsa, típicos do Brasil, foram analisados em relação ao seu conteúdo de fenólicos, incluindo ácido elágico, tido como potente antimutagênico e anticancerígeno, e capacidade antioxidante dos extratos metanólicos. A capacidade antioxidante variou cem vezes entre as

  17. Cyberbullying: percepções acerca do fenômeno e das estratégias de enfrentamento

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    Sidclay Bezerra Souza

    2014-01-01

    Full Text Available O cyberbullying, caracterizado como um dos tipos de violência em contexto educativo, apresenta-se como uma das principais causas do mal-estar vivido por seus protagonistas. O estudo inserido no Projeto Cyberbullying - o diagnóstico da situação em Portugal pretendeu compreender o fenômeno a partir das vivências de 118 estudantes do primeiro ano do Ensino Superior público português, que responderam a um questionário. Pudemos perceber a percepção dos alunos sobre o fenômeno e a importância que pares, professores e pais apresentam no enfrentamento e prevenção do cyberbullying. Tais resultados orientam-se no sentido do desenvolvimento sistêmico de comunidades que se fortalecem internamente para que cada um se sinta autorizado a intervir e a cuidar dos que nelas são vítimas de violência.

  18. El fenómeno Fujimori y la crisis política en el Perú

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    Eduardo BUENO LEÓN

    2009-11-01

    Full Text Available RESUMEN: En el presente trabajo, se analizan las causas que determinan el fenómeno Fujimori en la coyuntura electoral de 1989- 90. Se plantea la tesis que la "Fujimorización" se produce al confluir tendencias sociales democratizadoras y políticamente excluídas con un generalizado rechazo popular al estamento político. El fenómeno "integra" estas variables y desarticula la escena electoral que se presentaba artificialmente definida. Se plantea de esta forma, la posibilidad de la relegitimación del escenario político peruano y la afirmación autónoma de nuevos actores sociales y políticos.ABSTRACT: In this article, the author studies the causes which determined the phenomenon "Fujimori" in Peru in the 1989-90 elections. The main thesis is that "Fujimorización" arised in a context where different social democratic and politically excluded tendencies gathered with a popular rejection to the political class. This phenomenon "integrated" these variables and it produced a desarticulation of the electoral scene which was presented as artificially defined. In the new context it is posible to relegitimate the Perurian political scene and the autonomous assert of the new social and political actors.

  19. Measurement of 55Fe(n ,p ) cross sections by the surrogate-reaction method for fusion technology applications

    Science.gov (United States)

    Pandey, Bhawna; Desai, V. V.; Suryanarayana, S. V.; Nayak, B. K.; Saxena, A.; Mirgule, E. T.; Santra, S.; Mahata, K.; Makawana, R.; Abhangi, M.; Basu, T. K.; Rao, C. V. S.; Jakhar, S.; Vala, S.; Sarkar, B.; Agrawal, H. M.; Kaur, G.; Prajapati, P. M.; Pal, Asim; Sarkar, D.; Kundu, A.

    2016-02-01

    We have measured the proton decay probabilities of the *56Fe and *47Ti compound systems which are populated by the transfer reactions 52Cr(6Li,d ) *56Fe (surrogate of n +55Fe→*56Fe→p +55Mn ) and 45Sc(6Li,α ) *47Ti (surrogate of n +46Ti→47Ti*→p +46Sc ) reactions, respectively. The 55Fe(n ,p ) cross sections were then obtained in the equivalent neutron energy range of 7.9 to 20.1 MeV within the framework of the surrogate-reaction method. The measured results were compared with predictions of the empire-3.2.3 statistical model code and various recent evaluated data libraries. The experimental cross-section data on 55Fe(n ,p ) are in reasonable agreement with EAF-2010, while the TENDL-2014 and ROSFOND-2010 data show some discrepancies. This study demonstrates the possibility of determining neutron-induced charged particle emission cross sections for unstable radionuclides relevant to fusion technology applications by the surrogate-reaction method.

  20. Algumas reflexões para estabelecer a cronologia do "fenômeno transexual" (1910-1995

    Directory of Open Access Journals (Sweden)

    Pierre-Henri Castel

    2001-01-01

    Full Text Available O "fenômeno transexual" (Benjamin é um indicador muito seguro das modificações históricas da percepção científica, mas também cultural e política da identidade sexual no século XX. Para apresentar uma cronologia e uma bibliografia escolhida desse fenômeno, este artigo propõe um fio condutor: a recusa sistemática das interpretações psicanalíticas do transexualismo pelos sexólogos, endocrinologistas e sociólogos que estudaram o problema.The "Transsexual Phenomenon" (Benjamin is a reliable index of the historical modifications of scientific, cultural and political perception of sexual identity in the 20th century. As an introduction to a chronology and selected bibliography of this phenomenon, I suggest a clue: the systematic denial of the relevance of psychoanalytic explanations of transsexualism by all the biologists, endocrinologists and sociologists who dealt with the problem.

  1. Microfungal oasis in an oligotrophic desert: diversity patterns and community structure in three freshwater systems of Cuatro Ciénegas, Mexico

    Science.gov (United States)

    Gasca-Pineda, Jaime; Rosique-Gil, Edmundo; Eguiarte, Luis E.; Espinosa-Asuar, Laura

    2016-01-01

    The Cuatro Ciénegas Basin (CCB) comprises several oligotrophic aquatic ecosystems limited by phosphorus. These aquatic systems are dominated by a high prokaryotic diversity, shaped by the stress of low nutrient supplies and interspecific competition. Although fungi constitute a diverse and important component of microbial diversity, the microfungal diversity in the CCB remains to be unveiled. With the aim to explore microfungal diversity and ecological patterns in this area, we present the first investigation analyzing cultivable taxa from sediment and water, as well as lignocellulolytic taxa obtained from incubated submerged plant debris, and wood panels in three contrasting freshwater systems in the CCB: Churince, Becerra and Pozas Rojas. We chose a culture-based approach to analyze sediment and water samples in order to obtain fungal cultures, providing opportunities for a posteriori studies, and the possibility of ex situ preservation of the diversity. We evaluated sequence data from the nuclear ribosomal internal transcribed spacer including the 5.8 rDNA region for 126 isolates, revealing 37 OTUs. These OTUs were phylogenetically affiliated to several genera in the fungal phyla: Zygomycota, Basidiomycota, and Ascomycota. We recorded two OTUs with saline affinity, agreeing with previous findings on the prokaryotic communities with ancestral marine resemblances. All the studied systems showed moderate diversity levels, however discrepancies among the diversity indexes were observed, due to the occurrence of abundant taxa in the samples. Our results indicated that lignocellulolytic microfungal communities are dominated by transient fungal taxa, as resident species were not recorded perhaps as a result of the long-term strong competition with the highly adapted prokaryotic community. Moreover, the obtained microfungal taxa occurred mostly on the resident plant debris, rather than submerged wood panels, perhaps as a result of the high adaptation to specific

  2. How do Bacteria Adapt to the Red Sea? Cultivation and Genomic and Physiological Characterization of Oligotrophic Bacteria of the PS1, OM43, and SAR11 Clades

    KAUST Repository

    Jimenez Infante, Francy M.

    2015-05-01

    Given the high salinity, prevailing annual high temperatures, and ultra-oligotrophic conditions in the Red Sea isolation and characterization of important microbial groups thriving in this environment is important in understanding the ecological significance and metabolic capabilities of these communities. By using a high-­throughput cultivation technique in natural seawater amended with minute amounts of nutrients, members of the rare biosphere (PS1), methylotrophic Betaproteobacteria (OM43), and the ubiquitous and abundant SAR11 group (Pelagibacterales), were isolated in pure culture. Phylogenetic analyses of Red Sea isolates along with comparative genomics with close representatives from disparate provinces revealed ecotypes and genomic differentiation among the groups. Firstly, the PS1 alphaproteobacterial clade was found to be present in very low abundance in several metagenomic datasets form divergent environments. While strain RS24 (Red Sea) harbored genomic islands involved in polymer degradation, IMCC14465 (East (Japan) Sea) contained unique genes for degradation of aromatic compounds. Secondly, methylotrophic OM43 bacteria from the Red Sea (F5, G12 and H7) showed higher similarities with KB13 isolate from Hawaii, forming a ‘H-­RS’ (Hawaii-­Red Sea) cluster separate from HTCC2181 (Oregon isolate). HTCC2181 members were shown to prevail in cold, productive coastal environments and had an nqrA-­F system for energy generation by sodium motive force. On the contrary, H-­RS cluster members may be better adapted to warm and oligotrophic environments, and seem to generate energy by using a proton-­translocating NADH:Quinone oxidoreductase (complex I; nuoA-­N subunits). Moreover, F5, G12, and H7 had unique proteins related to resistance to UV, temperature and salinity, in addition to a heavy metal ‘resistance island’ as adaptive traits to cope with the environmental conditions in the Red Sea. Finally, description of the Red Sea Pelagibacterales

  3. Spatial variations in microbial community composition in surface seawater from the ultra-oligotrophic center to rim of the South Pacific Gyre.

    Directory of Open Access Journals (Sweden)

    Qi Yin

    Full Text Available Surface seawater in the South Pacific Gyre (SPG is one of the cleanest oceanic environments on earth, and the photosynthetic primary production is extremely low. Despite the ecological significance of the largest aquatic desert on our planet, microbial community composition in the ultra-oligotrophic seawater remain largely unknown. In this study, we collected surface seawater along a southern transect of the SPG during the Integrated Ocean Drilling Program (IODP Expedition 329. Samples from four distinct sites (Sites U1368, U1369, U1370 and U1371 were examined, representing ~5400 kilometers of transect line from the gyre heart to the edge area. Real-time PCR analysis showed 16S rRNA gene abundance in the gyre seawater, ranging from 5.96×10(5 to 2.55×10(6 copies ml(-1 for Bacteria and 1.17×10(3 to 1.90×10(4 copies ml(-1 for Archaea. The results obtained by statistic analyses of 16S rRNA gene clone libraries revealed the community composition in the southern SPG area: diversity richness estimators in the gyre center (Sites U1368 & U1369 are generally lower than those at sites in the gyre edge (Sites U1370 & U1371 and their community structures are clearly distinguishable. Phylogenetic analysis showed the predominance of Proteobacteria (especially Alphaproteobacteria and Cyanobacteria in bacterial 16S rRNA gene clone libraries, whereas phylotypes of Betaproteobacteria were only detected in the central gyre. Archaeal 16S rRNA genes in the clone libraries were predominated by the sequences of Marine Group II within the Euryarchaeota, and the Crenarchaeota sequences were rarely detected, which is consistent with the real-time PCR data (only 9.9 to 22.1 copies ml(-1. We also performed cultivation of heterotrophic microbes onboard, resulting in 18.9% of phylogenetically distinct bacterial isolates at least at the species level. Our results suggest that the distribution and diversity of microbial communities in the SPG surface seawater are closely

  4. Fens, seasonal wetlands, and the unconfined pumice aquifer east of the Cascade Range, south-central Oregon

    Science.gov (United States)

    Cummings, M. L.; Large, A.; Mowbray, A.; Weatherford, J.; Webb, B.

    2013-12-01

    Fens and seasonal wetlands in the headwaters of the Klamath and Deschutes river basins in south-central Oregon are present in an area blanketed by 2 to 3 m of pumice during the Holocene eruption of Mount Mazama. The lower pumice unit, moderately sorted coarse pumice lapilli to blocks (0.3 to 0.7 cm), phenocrysts, and lithics is 1.5 to 2 m thick; the upper pumice unit, poorly sorted lapilli to blocks (0.2 to 6 cm), minor phenocrysts, and lithics is 1 m thick. Pumice is a perched, unconfined aquifer over low permeability bedrock or pre-eruption fine-grained sediment. Early landscape response included partial erosion of pumice from pre-eruption valleys followed by partial filling by alluvium: phenocryst- and lithic-rich sand grading upward to glassy silt with rounded pumice pebbles. Groundwater-fed wetlands, fens, associated with the unconfined pumice aquifer occur as areas of diffuse groundwater discharge through gently sloping, convex surfaces underlain by up to 1.4 m of peat. Locally, focused discharge through the confining peat layer feeds low discharge streams. Carnivorous plants (sundews and pitcher plants) may be present. The sharp contact between peat and underlying pumice is an erosion surface that cuts progressively deeper into the upper and lower pumice units downslope. At the base of the slope peat with fen discharge feeding surface flow, alluvium with no surface flow, or a subtle berm separating the slope underlain by peat from the valley bottom underlain by alluvium may be present. Distinct vegetation changes take place at this transition. The erosion surface that underlies the peat layer in the fen is at the surface on the opposing valley wall and progressively rises up through the lower and upper pumice units: iron staining and cementation of pumice is locally prominent. Up to 1.5 m difference in water table occurs between the fen and opposing valley wall. Water table in piezometers screened in peat is at the surface. Locally, water table screened in

  5. Compostos fenólicos e capacidade antioxidante de cultivares de uvas Vitis labrusca L. e Vitis vinifera L. Phenolic compounds and antioxidant activity of Vitis labrusca and Vitis vinifera cultivars

    Directory of Open Access Journals (Sweden)

    Lucile Tiemi Abe

    2007-06-01

    Full Text Available O conteúdo de compostos fenólicos, incluindo resveratrol, antocianinas e outros flavonóides, e a capacidade antioxidante de cinco cultivares de uvas produzidas em Minas Gerais foram determinados. O conteúdo de fenólicos totais, determinado através do método de Folin-Ciocalteau variou significativamente, entre 65 ± 1 e 390 ± 30 mg equivalentes de ácido gálico.100 g -1 de amostra base úmida (b.u.. O conteúdo de antocianinas totais quantificado por CLAE variou entre 6,7 ± 0,2 e 154 ± 4 mg equivalentes de cianidina.100 g -1 (b.u.. Outros flavonóides encontrados foram catequina, epicatequina, quercetina, caempferol além dos ácidos hidroxicinâmicos. O resveratrol foi encontrado em três cultivares, variando entre 0,022 ± 0,001 e 0,60 ± 0,03 mg.100 g -1 (b.u.. A capacidade antioxidante foi analisada usando o método de seqüestro de radicais livres do DPPH (2,2-difenil-1-picrilhidrazila, que variou entre 2,7 ± 0,1 e 19 ± 2 µmoles equivalentes de Trolox.g -1 de amostra (b.u., mostrando boa correlação com o conteúdo de fenólicos totais. As uvas tintas de coloração mais escura apresentaram maior conteúdo de antocianinas, e conseqüentemente maior teor de fenólicos totais e capacidade antioxidante.Phenolic compounds including resveratrol, anthocyanins and other flavonoids and antioxidant capacity were evaluated for five grape cultivars cultivated in Minas Gerais (Brazil. The content of total phenolic determined by the Folin Ciocalteau method varied significantly, from 65 ± 1 to 390 ± 30 mg gallic acid equivalents.100 g -1 of FW (Fresh Weight. The content of total anthocyanins quantified by HPLC varied from 6.7 ± 0.2 to 154 ± 4 mg of cyanidin equivalents.100 g -1 FW. Resveratrol was found in three cultivars, in contents from 0.022 ± 0.001 to 0.60 ± 0.03 mg.100 g¹ of FW. In addition to hydroxicynnamic acids, other flavonoids such as catechin, epicatechin, quercetin and kaempferol were also present. The antioxidant

  6. Compuestos fenólicos del grano de maíz y su relación con el oscurecimiento de masa y tortilla

    OpenAIRE

    Yolanda Salinas Moreno; José de J. López Reynoso; Guadalupe B. González Flores; Gricelda Vázquez Carrillo

    2007-01-01

    Algunos de los híbridos y variedades de maíz cultivados en el Estado de México producen masa y tortilla que se oscurecen. No se conoce la causa de este oscurecimiento, pero los compuestos fenólicos del grano podrían estar involucrados. Los objetivos del presente estudio fueron determinar si el contenido de compuestos fenólicos en el grano de maíz está relacionado con el oscurecimiento de masa y tortilla en los maíces evaluados, y obtener el perfil de ácidos fenólicos en muestras de maíz cuya ...

  7. Modeling plankton ecosystem functioning and nitrogen fluxes in the oligotrophic waters of the Beaufort Sea, Arctic Ocean: a focus on light-driven processes

    Directory of Open Access Journals (Sweden)

    V. Le Fouest

    2013-07-01

    Full Text Available The Arctic Ocean (AO undergoes profound changes of its physical and biotic environments due to climate change. In some areas of the Beaufort Sea, the stronger haline stratification observed in summer alters the plankton ecosystem structure, functioning and productivity, promoting oligotrophy. A one-dimension (1-D physical–biological coupled model based on the large multiparametric database of the Malina project in the Beaufort Sea was used (i to infer the plankton ecosystem functioning and related nitrogen fluxes and (ii to assess the model sensitivity to key light-driven processes involved in nutrient recycling and phytoplankton growth. The coupled model suggested that ammonium photochemically produced from photosensitive dissolved organic nitrogen (i.e., photoammonification process was a necessary nitrogen source to achieve the observed levels of microbial biomass and production. Photoammonification directly and indirectly (by stimulating the microbial food web activity contributed to 70% and 18.5% of the 0–10 m and whole water column, respectively, simulated primary production (respectively 66% and 16% for the bacterial production. The model also suggested that variable carbon to chlorophyll ratios were required to simulate the observed herbivorous versus microbial food web competition and realistic nitrogen fluxes in the Beaufort Sea oligotrophic waters. In face of accelerating Arctic warming, more attention should be paid in the future to the mechanistic processes involved in food webs and functional group competition, nutrient recycling and primary production in poorly productive waters of the AO, as they are expected to expand rapidly.

  8. Estimates of vertical turbulent mixing used to determine a vertical gradient in net and gross oxygen production in the oligotrophic South Pacific Gyre

    Science.gov (United States)

    Haskell, W. Z.; Prokopenko, M. G.; Stanley, R. H. R.; Knapp, A. N.

    2016-07-01

    Mixed layer (ML) gross (GOP) and net (NOP) oxygen production rates based on in situ mass balances of triple oxygen isotopes (TOI) and O2/Ar are influenced by vertical transport from below, a term traditionally difficult to constrain. Here we present a new approach to estimate vertical eddy diffusivity (Kz) based on density gradients in the upper thermocline and wind speed-based rates of turbulent shear at the ML depth. As an example, we use this Kz, verified by an independent 7Be-based estimate, in an O2/TOI budget at a site in the oligotrophic South Pacific Gyre. NOP equaled 0.31 ± 0.16 mmol m-2 d-1 in the ML (~55-65 m depth) and 1.2 ± 0.4 mmol m-2 d-1 (80%) beneath the ML, while GOP equaled 74 ± 27 mmol m-2 d-1 (86%) in the ML and 12 ± 4 mmol m-2 d-1 (14%) below, revealing a vertical gradient in production rates unquantifiable without the Kz estimate.

  9. Comparative metagenomics of two microbial mats at Cuatro Ciénegas Basin II: community structure and composition in oligotrophic environments.

    Science.gov (United States)

    Bonilla-Rosso, Germán; Peimbert, Mariana; Alcaraz, Luis David; Hernández, Ismael; Eguiarte, Luis E; Olmedo-Alvarez, Gabriela; Souza, Valeria

    2012-07-01

    Microbial mats are self-sustained, functionally complex ecosystems that make good models for the understanding of past and present microbial ecosystems as well as putative extraterrestrial ecosystems. Ecological theory suggests that the composition of these communities might be affected by nutrient availability and disturbance frequency. We characterized two microbial mats from two contrasting environments in the oligotrophic Cuatro Ciénegas Basin: a permanent green pool and a red desiccation pond. We analyzed their taxonomic structure and composition by means of 16S rRNA clone libraries and metagenomics and inferred their metabolic role by the analysis of functional traits in the most abundant organisms. Both mats showed a high diversity with metabolically diverse members and strongly differed in structure and composition. The green mat had a higher species richness and evenness than the red mat, which was dominated by a lineage of Pseudomonas. Autotrophs were abundant in the green mat, and heterotrophs were abundant in the red mat. When comparing with other mats and stromatolites, we found that taxonomic composition was not shared at species level but at order level, which suggests environmental filtering for phylogenetically conserved functional traits with random selection of particular organisms. The highest diversity and composition similarity was observed among systems from stable environments, which suggests that disturbance regimes might affect diversity more strongly than nutrient availability, since oligotrophy does not appear to prevent the establishment of complex and diverse microbial mat communities. These results are discussed in light of the search for extraterrestrial life. PMID:22920516

  10. Methane release from sediment seeps to the atmosphere is counteracted by highly active Methylococcaceae in the water column of deep oligotrophic Lake Constance.

    Science.gov (United States)

    Bornemann, Maren; Bussmann, Ingeborg; Tichy, Lucas; Deutzmann, Jörg; Schink, Bernhard; Pester, Michael

    2016-08-01

    Methane emissions from freshwater environments contribute substantially to global warming but are under strong control of aerobic methane-oxidizing bacteria. Recently discovered methane seeps (pockmarks) in freshwater lake sediments have the potential to bypass this control by their strong outgassing activity. Whether this is counteracted by pelagic methanotrophs is not well understood yet. We used a (3)H-CH4-radiotracer technique and pmoA-based molecular approaches to assess the activity, abundance and community structure of pelagic methanotrophs above active pockmarks in deep oligotrophic Lake Constance. Above profundal pockmarks, methane oxidation rates (up to 458 nmol CH4 l(-1) d(-1)) exceeded those of the surrounding water column by two orders of magnitude and coincided with maximum methanotroph abundances of 0.6% of the microbial community. Phylogenetic analysis indicated a dominance of members of the Methylococcaceae in the water column of both, pockmark and reference sites, with most of the retrieved sequences being associated with a water-column specific clade. Communities at pockmark and reference locations also differed in parts, which was likely caused by entrainment of sediment-hosted methanotrophs at pockmark sites. Our results show that the release of seep-derived methane to the atmosphere is counteracted by a distinct methanotrophic community with a pronounced activity throughout bottom waters. PMID:27267930

  11. Greenhouse gas emissions from a drained fen peatland cultivated with reed canary grass for biogas production

    Energy Technology Data Exchange (ETDEWEB)

    Kandel, T.P.

    2013-10-01

    Cultivated peatlands are significant sources of CO{sub 2} as the drainage and subsequent agricultural practices such as tillage and fertilization enhances the decomposition of soil organic carbon. However, use of the peatlands for perennial energy crop production could help to reduce the CO{sub 2} emissions as annual ploughing is avoided in perennial cropping systems and fertilizer requirements is also lower compared to annual arable crops. However, crop managements such as fertilization and harvesting of those energy crops are also important in respect to total GHG balance. Moreover, economical viability of energy crop production in peatland need to be considered which requires studies on best management practices to produce high biomass and energy per hectare of land with as little input of resources as possible. In the first study, annual net ecosystem balance of CO{sub 2} from a riparian fen peatland used for annual arable crop and perennial energy crop cultivation was compared. Fluxes of CO{sub 2} were measured with closed chambered methods which were later partitioned into light depended gross photosynthesis (GP) and light independent ecosystem respiration (R{sub E}). The annual flux of CO{sub 2} was estimated by modelling GP and R{sub E} separately and extrapolating the obtained parameters in relation to environmental and biomass measurements. Model performances of commonly used GP and R{sub E} models were enhanced by introducing ratio vegetation index (RVI) as proxy for active leaf area index. Both GP and R{sub E} showed strong seasonal pattern as expected. An expected higher annual GP was observed in the RCG cultivation system which was favored by a longer growth period, but R{sub E} was also higher which was mainly contributed by higher plant respiration. Annual net ecosystem exchange (NEE) of CO{sub 2} was close to zero for both cropping systems and thus no apparent advantage of the energy cropping system was observed during crop cultivation. Another

  12. Comprensión de fenómenos naturales desde la perspectiva científica desde el contexto ecosistemas

    OpenAIRE

    Zepeda Navarrete, José Alejandro; Zacarías Pérez, Patricia; Ramírez Ponce, Ramón; Martínez Díaz, Francisco René; Reyes Matias, Danilka

    2012-01-01

    • Información General • Evaluación Diagnóstica • Contenido o Tema 1 - ¿Qué significa la competencia comprensión de fenómenos y procesos naturales desde la perspectiva científica en el contexto de los ecosistemas?  Objetivos específicos del tema  Actividad inicial del tema  Desarrollo del tema  Actividad final del tema  Recursos adicionales o Tema 2 - ¿Por qué es relevante que adquiera la competencia comprensión de fenómenos y procesos naturales desde la perspec...

  13. La Interacción Mutua entre Fuentes y las Aparentes Anomalías en el Fenómeno de Interferencia

    OpenAIRE

    Reinaldo Welti

    2002-01-01

    En la mayoría de los textos de física del nivel básico universitario al tratar el fenómeno de interferencia suponen que las fuentes irradian de la misma forma cualquiera sea la distancia entre ellas. En algunas situaciones esta suposición puede llevar a aparentes anomalías en la conservación de la energía. En este trabajo se muestra que estas anomalías se resuelven solamente si el fenómeno de interferencia se presenta en un contexto que tenga en cuenta las interacciones entre las fuentes y el...

  14. Análisis preeliminar de carotenoides y compuestos fenólicos en frutos de zapote mamey (Pouteria sapota (Jacq.) H.E. Moore & Stearn)

    OpenAIRE

    R. M. Soto-Hernández; I. Alia-Tejacal; M. T. Colinas-León; M. T. Martínez-Damián

    2005-01-01

    La pulpa del fruto de zapote mamey contiene cantidades considerables de carotenoides y compuestos fenólicos, recientemente el consumo de estos metabolitos se han asociado con la disminución de enfermedades cardiovasculares y cáncer. Por otra parte, los fenoles están relacionados con el oscurecimiento de la pulpa lo cual disminuye la vida poscosecha del fruto. El presente estudio tuvo como objetivo realizar un análisis de los carotenoides y compuestos fenólicos presentes en la pulpa del fruto ...

  15. Estudio de la biodegrabilidad de mezclas de compuestos fenólicos alquil-sustituidos bajo condiciones de metanogénesis

    OpenAIRE

    Meza Vudoyra, Miguel Angel

    2013-01-01

    Con el objetivo de evaluar la biodegradabilidad de compuestos fenólicos, en sistemas continuos y en lotes, bajo condiciones de metanogénesis, utilizando diversas mezclas y determinar las velocidades específicas de biodegradación de los compuestos alquil-fenólicos, se investigó el efecto del orto y meta-cresol sobre la biodegradabilidad del fenol y para-cresol, utilizando lodo granular metano génico adaptado. Se utilizaron dos reactores continuos tipo UASB y botellas serológicas en las que se ...

  16. Síntese de derivados de ácidos fenólicos e estudo da sua actividade antioxidante

    OpenAIRE

    Reis, Bruno Miguel Macedo da Silva

    2008-01-01

    A peroxidação lipídica, além de causar sérios danos no corpo humano, é a principal causa da deterioração dos alimentos afectando a sua cor, aroma e valor nutricional, o que conduz a uma diminuição do seu ciclo de vida. O fenómeno de oxidação pode ser retardado com recurso a antioxidantes, de origem natural ou sintética, que inibam a formação de espécies reactivas, ou que reajam com estas, formando posteriormente radicais com menor grau de reactividade. Nesta dissertação proc...

  17. El fenómeno de las redes sociales y los cambios en la vigencia de los Derechos Fundamentales

    OpenAIRE

    Gil Antón, Ana María

    2012-01-01

    Este trabajo aborda, de manera sintética, uno de los problemas más relevantes con los que nos estamos encontrando en el Siglo XXI resultado del fenómeno de Internet, el de las redes sociales que constituyen vías consolidadas de relación e interacción cotidianas, no sólo de las nuevas generaciones de adolescentes y jóvenes, sino también de todo el conjunto de nuestra sociedad. Y pese a que la utilización de las nuevas Tecnologías de la Información y Comunicación ofrece gra...

  18. Greenhouse gas emissions of drained fen peatlands in Belarus are controlled by water table, land use, and annual weather conditions

    Science.gov (United States)

    Burlo, Andrei; Minke, Merten; Chuvashova, Hanna; Augustin, Jürgen; Hoffmann, Mathias; Narkevitch, Ivan

    2014-05-01

    Drainage of peatlands causes strong emission of the greenhouse gases (GHG) CO2 and N2O, sometimes combined with a weak CH4 uptake. In Belarus drained peatlands occupy about 1505000 ha or more than 7.2 % of the country area. Joosten (2009) estimates CO2 emission from degraded peatlands in Belarus as 41.3 Mt yr-1 what equals to 47 % of total anthropogenic greenhouse gases (GHGs) emission of country in 2011. However, it could not be checked if these numbers are correct since there are no GHG measurements on these sites up to now. Therefore we studied the GHG emissions with the closed chamber approach in four peatlands situated in central and southern Belarus over a period from August 2010 to August 2012. The measurements comprised eight site types representing different water level conditions, and ranging from grassland and arable land over abandoned fields and peat cuts to near-natural sedge fens. Fluxes of CH4 and N2O were determined using the close-chamber approach every second week in snow free periods and every fourth week during winter time. The annual emissions were calculated based on linear interpolation. Carbon dioxide exchange was measured with transparent and opaque chambers every 3-4 weeks and the annual net ecosystem exchange (NEE) was modeled according to Drösler (2005). Most of the drained sites were sources of CO2 in both years. NEE increased with lower mean annual water table level. The highest NEE value (1263.5 g CO2-C m-1yr-1) was observed at the driest site of the study; an abandoned fen formerly used for agriculture. In contrast, a former peat extraction site with moist peat and small Pinus sylvestris tress were sinks of CO2 with uptake to 389.6 g CO2-C m-1yr-1. The highest N2O emissions were recorded at a drained agricultural fen with mean annual rates of up to 2347 mg N2O-N m-2 yr-1. Significant fluxes of CH4 (15 g CH4C m-2 h-1) were observed only at the near-natural site in the first year of investigation when precipitation and the mean water

  19. El tratamiento de fenómenos físicos para aprender matemáticas

    OpenAIRE

    Cortés, Gildardo; Ramírez, Pericles

    2005-01-01

    La historia de la ciencia muestra la íntima relación entre la física y la matemática y cómo en nuestros días esta relación, en el ambiente escolar, se ha ido perdiendo. Nuestro planteamiento intenta recuperar el papel de la experimentación en el aula. Proponemos diseños de aprendizaje basados en prácticas de modelación de fenómenos físicos, para que alumnos construyan conocimientos con significado. En el documento damos evidencia de cómo este planteamiento puede ser posible. La investigación ...

  20. Mapeamento do fenômeno de pulsações não-radiais no DHR

    Science.gov (United States)

    Waelkens, A. H.; Janot Pacheco, E.

    2003-08-01

    Neste trabalho de IC, pretende-se estabelecer um mapa das características do fenômeno das pulsações não-radiais (PNR) no diagrama HR (DHR). Trata-se de oscilações que não mantém a homotecia radial. O fenômeno foi inicialmente descoberto no Sol nos anos 60 e hoje é detectado num grande número de objetos. Sua grande importância reside em que as pulsações descrevem a física da cavidade em que se propagam. As PNR são classificadas basicamente por suas frequências, amplitudes e certos números quânticos associados. Com o objetivo de descrever a variação desses parâmetros no DHR, procedeu-se a um extenso levantamento bibliográfico (artigos de revistas e outras fontes) cobrindo o tema. Compôs-se assim uma tabela, que será apresentada nesta comunicação, contendo os parâmetros físicos das estrelas (T, L, logg, M) e suas características de PNR, deduzidas a partir de observações fotométricas e/ou espectroscópicas. No momento, completamos os dados sobre as Anãs Brancas e Beta Cep. Apresentaremos no trabalho diagramas L-T com os últimos resultados obtidos, eventualmente com uma terceira dimensão que descreva características pulsacionais.

  1. Revictimización un fenómeno invisibilizado en las instituciones Revictimization an invisiblelized phenomena in institutions

    Directory of Open Access Journals (Sweden)

    Berenice Smith Bonilla

    2007-03-01

    Full Text Available El presente trabajo de investigación sobre la revictimiación institucional pone de manifiesto la existencia de dicho fenómeno dentro del sistema judicial. Se analizan las causas de esta situación la cual aparenta no tener la debida cobertura del sistema ni la de los propios funcionarios que laboran en tal situación. Se hace una exposición de motivos que explica el fenómeno que incluye las políticas existentes, las estrategias de capacitación, difusión y consistencia. Además se estudia la existencia de la Oficina de Atención a la Víctima del Delito desde su iniciativa, la cual catapulta la figura de la víctima a un lugar hasta entonces negado, sin que su actuar trascienda al ámbito requerido por razones que se analizan. En las conclusiones se brindan recomendaciones pertinentes para quienes están sufriendo como victimas por su labor.This investigation about institutional revictimization demonstrates the existence of this phenomenon within the judicial system. The causes of this situation are analyzed, that seems not to have the appropriate coverage from the system nor from the employees of the institutions. An exposition of the different motives is done to explain the phenomenon that includes current policies, capacitating strategies, diffusion and consistency. Also the existence of the Attention to Victim of Crime Office is studied from its initiative, which catapults the victim figure to a previously denied place. As conclusions, some recommendations are brought for those who are suffering as victims.

  2. La fibra óptica y el fenómeno no lineal mezcla de cuarta onda

    Directory of Open Access Journals (Sweden)

    Fabián Gómez López

    2015-12-01

    Full Text Available RESUMEN Para aprovechar de mejor manera el ancho de banda que tiene la fibra óptica, los sistemas de comunicaciones ópticos han tenido que aumentar la potencia de transmisión de las señales para poder transportar a grandes distancias la información. Debido a lo anterior, comienzan a producirse ciertos fenómenos ópticos no lineales como la mezcla de cuarta onda (Four Wave Mixing, FWM, que degradan la señal de información. En este documento se realiza un estado del arte de la fibra óptica y un estudio del fenómeno no lineal FWM, que se genera cuando dos o más señales ópticas se propagan en la fibra, lo cual conlleva a una mezcla de señales que puede generar nuevos componentes de interferencia de la señal óptica transmitida. ABSTRACT To make better use of the bandwidth that has the optical fiber, optical communications systems have had to increase the transmission power of signals to transport information over long distances. Because of this, certain nonlinear optical phenomena such as four wave mixing (Four Wave Mixing, FWM, which degrade the information signal begin to occur. Herein a state of the art of optical fiber and a study of the nonlinear FWM phenomenon, which is generated when two or more optical signals propagating in the fiber takes place, which leads to a mixture of signals that can generate new components interference of the transmitted optical signal.

  3. Effects of experimental water table and temperature manipulations on ecosystem CO2 fluxes in an Alaskan rich fen

    Science.gov (United States)

    Chivers, M.R.; Turetsky, M.R.; Waddington, J.M.; Harden, J.W.; McGuire, A.D.

    2009-01-01

    Peatlands store 30% of the world's terrestrial soil carbon (C) and those located at northern latitudes are expected to experience rapid climate warming. We monitored growing season carbon dioxide (CO2) fluxes across a factorial design of in situ water table (control, drought, and flooded plots) and soil warming (control vs. warming via open top chambers) treatments for 2 years in a rich fen located just outside the Bonanza Creek Experimental Forest in interior Alaska. The drought (lowered water table position) treatment was a weak sink or small source of atmospheric CO2 compared to the moderate atmospheric CO2 sink at our control. This change in net ecosystem exchange was due to lower gross primary production and light-saturated photosynthesis rather than increased ecosystem respiration. The flooded (raised water table position) treatment was a greater CO2 sink in 2006 due largely to increased early season gross primary production and higher light-saturated photosynthesis. Although flooding did not have substantial effects on rates of ecosystem respiration, this water table treatment had lower maximum respiration rates and a higher temperature sensitivity of ecosystem respiration than the control plot. Surface soil warming increased both ecosystem respiration and gross primary production by approximately 16% compared to control (ambient temperature) plots, with no net effect on net ecosystem exchange. Results from this rich fen manipulation suggest that fast responses to drought will include reduced ecosystem C storage driven by plant stress, whereas inundation will increase ecosystem C storage by stimulating plant growth. ?? 2009 Springer Science+Business Media, LLC.

  4. Carbon Dioxide and Methane Dynamics Trough Fen-Stream-Lake Continuum in North Boreal Zone, Finnish Lapland

    Science.gov (United States)

    Juutinen, S.; Kuutti, V.; Valiranta, M.; Seppä, H.; Weckstrom, J.; Tuittila, E.

    2006-12-01

    This study aims to determine spatial and temporal variation in carbon dioxide (CO2) and methane (CH4) dynamics through a fen-lake continuum. Study was carried out in a catchment dominated by aapa mire over the period from spring 2005 to autumn 2006 in north boreal zone in Finnish Lapland. The study region characteristically has very high lake and mire density. To cover spatial variability we set measurement plots to different plant communities along moisture gradient in the fen and to different positions in the stream and lake. Six different mire communities, stream input to lake marginal mire, a lower stream site, lake in- and output sites, and three littoral and one pelagial site were measured. We measured CO2 and CH4 gas fluxes using closed chamber technique, and dissolved CO2 and CH4 concentrations using headspace equilibration technique weekly to biweekly over the open water season. In association of gas sampling peat and water temperatures, water levels in mire and lake, and stream flow rate were measured. Catchment boundaries and proportions of mire, lake and mineral soil area were determined using topographic maps, aerial photograph and field survey. Precipitation data is achieved from nearby weather station. We will present results of spatial and temporal pattern and seasonal budget of wetland atmosphere exchange of CO2 and CH4. Our preliminary results indicate that there is input of dissolved CO2 and CH4 from mire to the lake. In addition, our observations indicate that there is spatial variation in gas flux dynamics in aquatic environments in relation to the differences in stream flow rate and sediment quality. Seasonally varying hydrology causes changes in gas flux dynamics in all studied wetland surfaces. Information from this study improve the knowledge of carbon transport and balances in northern aapa mire region, where mires are commonly affected by through flow from watershed, and where number of small lakes is great.

  5. Sentimentos do adolescente relacionados ao fenômeno BULLYING: possibilidades para a Assistência de Enfermagem nesse contexto

    Directory of Open Access Journals (Sweden)

    Agnes Schutz de Oliveira

    2006-04-01

    Full Text Available O bullying é um fenômeno devastador podendo vir a afetar a auto-estima e a saúde mental dos adolescentes. Geralmente ocorre quando o adolescente é mais suscetível ou vulnerável às agressões verbais ou morais que lhes causam angústia e dor, principalmente quando ocorrido em ambiente escolar traduzindo-se como uma forma de exclusão social. Pode desencadear alguns problemas de saúde tais como a anorexia, bulimia, depressão, ansiedade e até mesmo o suicídio. A enfermagem, pautada com princípios de prevenir agravos de diversos males, preocupa-se também com esta intercorrência traumática na adolescência. O objetivo deste estudo foi identificar sentimentos que possam estar relacionados com o bullying em adolescentes alunos de 5ª a 8ª séries. Tratou-se de uma pesquisa descritiva de abordagem qualitativa, realizada em uma escola de segmento religioso conveniada com o estado. A coleta de dados ocorreu auxiliada por entrevistas gravadas, posteriormente transcritas e submetidas à análise temática. Os resultados mostraram que os sentimentos relacionados ao fenômeno são múltiplos e variados, sendo categorizados como aspectos de caráter positivo, aspectos de caráter negativo e aspectos de caráter necessário.

  6. Changes of the CO2 and CH4 production potential of rewetted fens in the perspective of temporal vegetation shifts

    Directory of Open Access Journals (Sweden)

    D. Zak

    2014-10-01

    Full Text Available Rewetting of long-term drained fens often results in the formation of eutrophic shallow lakes with an average water depth of less than 1 m. This is accompanied by a fast vegetation shift from cultivated grasses via submerged hydrophytes to helophytes. As a result of rapid plant dying and decomposition, these systems are highly-dynamic wetlands characterised by a high mobilisation of nutrients and elevated emissions of CO2 and CH4. However, the impact of specific plant species on these phenomena is not clear. Therefore we investigated the CO2 and CH4 production due to the subaqueous decomposition of shoot biomass of five selected plant species which represent different rewetting stages (Phalaris arundinacea, Ceratophyllum demersum, Typha latifolia, Phragmites australis, and Carex riparia during a 154 day mesocosm study. Beside continuous gas flux measurements, we performed bulk chemical analysis of plant tissue, including carbon, nitrogen, phosphorus, and plant polymer dynamics. Plant specific mass losses after 154 days ranged from 25 (P. australis to 64% (C. demersum. Substantial differences were found for the CH4 production with highest values from decomposing C. demersum (0.4 g CH4 kg−1 dry mass day that were about 70 times higher than CH4 production from C. riparia. Thus, we found a strong divergence between mass loss of the litter and methane production during decomposition. If C. demersum as a hydrophyte is included in the statistical analysis solely nutrient contents (nitrogen and phosphorus explain varying GHG production of the different plant species while lignin and polyphenols demonstrate no significant impact at all. Taking data of annual biomass production as important carbon source for methanogens into account, high CH4 emissions can be expected to last several decades as long as inundated and nutrient-rich conditions prevail. Different restoration measures like water level control, biomass extraction and top soil removal are

  7. Comparación del contenido fenólico, capacidad antioxidante y actividad antiinflamatoria de infusiones herbales comerciales Comparison of phenolic content, antioxidant capacity and anti-inflamatory activity of commercial herbal infusions

    Directory of Open Access Journals (Sweden)

    Erika Elizabeth Muñoz-Velázquez

    2012-06-01

    Full Text Available En la actualidad, hay un incremento en el consumo de infusiones debido a sus propiedades benéficas, las cuales se atribuyen a la presencia de compuestos fenólicos. Por lo anterior, el objetivo de este estudio fue evaluar el contenido fenólico, la capacidad antioxidante y la actividad antiinflamatoria de infusiones comerciales de hierbabuena (Mentha piperita L., limón (Cymbopogon citratos, manzanilla (Matricaria chamomilla L., árnica (Heterotheca inuloides y boldo (Peumus boldus Molina obtenidas en un supermercado en 2009. El contenido de fenoles y la capacidad antioxidante se determinaron por técnicas espectrofotométricas. Adicionalmente, la identificación y cuantificación de compuestos fenólicos también se llevó a cabo por HPLC. La actividad antiinflamatoria se evaluó mediante la inhibición de la enzima ciclooxigenasa-2 (COX-2. La infusión de boldo presentó el mayor contenido de compuestos fenólicos y la mayor capacidad antioxidante medida por la técnicas ABT, seguida de las infusiones de hierbabuena por el m��todo de FRAP. En las infusiones evaluadas se identificaron diez diferentes compuestos, encontrándose en mayor concentración los compuestos catequina, epigalocatequina galato, ácido rosmarínico y eriocitrina. En cuanto a la capacidad inhibitoria sobre COX-2, las muestras de manzanilla y limón presentaron los mayores porcentajes de inhibición, seguida de la infusión de boldo. En general, los resultados sugieren que las infusiones comerciales de boldo y hierbabuena muestran propiedades biológicas con beneficios potenciales a la salud.Actually there is an increase on infusion consumption due their beneficial properties, which are attributable to the presence of phenolic compounds. By this reason, the aim of this study was to assess phenolic content, antioxidant capacity and anti-inflammatory capacity of commercial infusions of peppermint (Mentha piperita L., lemon grass (Cymbopogon citratos, chamomile (Matricaria

  8. Understanding the long term ecosystem stability of a fen mire by analyzing subsurface geology, eco-hydrology and nutrient stoichiometry - Case study of the Rospuda valley (NE Poland)

    NARCIS (Netherlands)

    Jabłońska, Ewa; Falkowski, Tomasz; Chormański, Jarosław; Jarzombkowski, Filip; Kłosowski, Stanisław; Okruszko, Tomasz; Pawlikowski, Paweł; Theuerkauf, Martin; Wassen, Martin J.; Kotowski, Wiktor

    2014-01-01

    We explored the background of differences in long-term stability between two parts in an undisturbed mire system (Rospuda fen, NE Poland). We re-constructed the Holocene history of the mire and compared it with current vegetation, water level dynamics, water chemistry and nutrient availability in tw

  9. Para Além do Estado e do Mercado: A Dádiva no Fenômeno dos Sem-Abrigo

    Directory of Open Access Journals (Sweden)

    João Aldeia

    2014-03-01

    Full Text Available Las reflexiones sobre el fenómeno de los sin techo tienden a reproducir las ausencias que el paradigma del don identifica en el pensamiento sobre las sociedades modernas occidentales. Recurrentemente, se considera al Estado y al mercado como las únicas esferas de regulación social y se los interpreta como los espacios de donde derivan las causas estructurales y las posibles soluciones para el fenómeno. Ello no permite una comprensión completa del tema y tampoco una reflexión consistente sobre los modos de minimizar las injusticias de la vida en la calle. Pensar sobre el fenómeno por medio del paradigma del don es relevante porque permite identificar la habitual invisibilización de las relaciones interpersonales no oficiales que caracterizan la vida en la calle, posibilitando, a su vez, la revalorización de estas interacciones en el debate sobre el fenómeno de los sin techo.

  10. Phosphate Release Upon Long- and Short -Term Flooding of Fen Meadows Depends on Land Use History and Soil pH

    NARCIS (Netherlands)

    Beltman, B.; Van Der Ven, P. J. M.; Verhoeven, J. T. A.; Sarneel, J. M.

    2014-01-01

    Flooding of acidified and desiccated fen meadows is a management approach for mitigating loss of plant species as well as a short-term measure to prevent flooding in urban areas. Studies have shown that flooding events can cause extreme P release from soils. We questioned whether the occurrence of t

  11. Phosphate release upon short- and long-term flooding of fen meadows depends on land use history and pH.

    NARCIS (Netherlands)

    Beltman, Boudewijn; van der Ven, P.J.M.; Verhoeven, Jos; Sarneel, J

    2014-01-01

    Flooding of acidified and desiccated fen meadows is a management approach for mitigating loss of plant species as well as a short-term measure to prevent flooding in urban areas. Studies have shown that flooding events can cause extreme P release from soils. We questioned whether the occurrence of t

  12. How a regional aquifer, a local aquifer and an oxbow lake impact on hydrological and biogeochemical processes in ariparian fen-meadow ecosystem

    DEFF Research Database (Denmark)

    Hoffmann, Carl Christian; Pedersen, Morten Lauge; Rasmussen, K. R.

    2009-01-01

    The groundwater flow pattern through a riparian fen-meadow was investigated by use of piezometer transects, soil survey, measurements of piezometric heads and measurements of hydraulic conductivity. Groundwater was sampled from piezometers and analysed for nitrate-N. Water balances and nitrate...

  13. Desarrollo de técnicas de extracción y análisis de antocianinas y compuestos fenólicos en Jaboticaba (Myrciaria Cauliflora)

    OpenAIRE

    Mera Morillo, Celia

    2015-01-01

    Desarrollo de técnicas de extracción mediante ultrasonidos y mediante fluidos presurizados para así, obtener las condiciones óptimas de extracción de las antocianinas mayoritarias y compuestos fenólicos totales presentes en la jaboticaba

  14. Compuestos fenólicos y flavonoides como marcadores bioquímicos de la respuesta a estrés abiótico en plantas tolerantes

    OpenAIRE

    CALATAYUD VAELLO, PAU

    2011-01-01

    Calatayud Vaello, P. (2010). Compuestos fenólicos y flavonoides como marcadores bioquímicos de la respuesta a estrés abiótico en plantas tolerantes. http://hdl.handle.net/10251/9179. Archivo delegado

  15. Fen1 does not control somatic hypermutability of the (CTG)(n)*(CAG)(n) repeat in a knock-in mouse model for DM1.

    NARCIS (Netherlands)

    Broek, W.J.A.A. van den; Nelen, M.R.; Heijden, G.W. van der; Wansink, D.G.; Wieringa, B.

    2006-01-01

    The mechanism of trinucleotide repeat expansion, an important cause of neuromuscular and neurodegenerative diseases, is poorly understood. We report here on the study of the role of flap endonuclease 1 (Fen1), a structure-specific nuclease with both 5' flap endonuclease and 5'-3' exonuclease activit

  16. Fenótipo cintura hipertrigliceridêmica: associação com alterações metabólicas em adolescentes

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    Maria Ester P. da Conceição-Machado

    2013-02-01

    Full Text Available OBJETIVO: O presente estudo objetivou identificar a prevalência do fenótipo cintura hipertrigliceridêmica (CHT e avaliar sua associação com alterações metabólicas em adolescentes de baixa condição econômica. MÉTODO: Estudo transversal com amostra probabilística de 1.076 adolescentes entre 11 e 17 anos, de ambos os sexos, estudantes de escolas públicas. Os participantes foram submetidos à avaliação antropométrica (peso, altura e circunferência da cintura e à dosagem dos níveis de colesterol total, LDL-C, HDL-C, colesterol não HDL, triglicérides (TG e glicemia de jejum. Foram obtidas informações referentes às condições econômicas das famílias dos participantes.O fenótipo CHT foi definido pela presença simultânea da circunferência da cintura aumentada (> percentil 90 por idade e sexo e dos níveis séricos de triglicérides elevados (> 100 mg/dL. A análise de regressão logística foi utilizada para avaliação das associações de interesse. RESULTADOS: A prevalência do fenótipo CHT foi de 7,2% entre os adolescentes, sendo mais elevada na presença de obesidade (63,4%, do colesterol não HDL (16,6% e do LDL-C (13,7% altos. A análise bivariada indicou que, das variáveis metabólicas, apenas a glicemia não se associou ao fenótipo CHT. A análise multivariada, ajustada por sexo e idade, indicou que o fenótipo CHT se associou positivamente com o colesterol não HDL alto (odds ratio, 7,0; IC 95% 3,9-12,6 e com o HDL-C baixo (odds ratio, 2,7; IC 95%, 1,5-4,8. CONCLUSÕES: Este estudo mostrou que o fenótipo CHT se associou com um perfil lipídico aterogênico e sugere esse fenótipo como uma ferramenta de screening que pode ser utilizada para identificar adolescentes com alterações metabólicas.

  17. Multivariate and phylogenetic analyses assessing the response of bacterial mat communities from an ancient oligotrophic aquatic ecosystem to different scenarios of long-term environmental disturbance.

    Science.gov (United States)

    Pajares, Silvia; Souza, Valeria; Eguiarte, Luis E

    2015-01-01

    Understanding the response of bacterial communities to environmental change is extremely important in predicting the effect of biogeochemical modifications in ecosystem functioning. The Cuatro Cienegas Basin is an ancient oasis in the Mexican Chihuahuan desert that hosts a wide diversity of microbial mats and stromatolites that have survived in extremely oligotrophic pools with nearly constant conditions. However, thus far, the response of these unique microbial communities to long-term environmental disturbances remains unexplored. We therefore studied the compositional stability of these bacterial mat communities by using a replicated (3x) mesocosm experiment: a) Control; b) Fluct: fluctuating temperature; c) 40C: increase to 40 ºC; d) UVplus: artificial increase in UV radiation; and f) UVmin: UV radiation protection. In order to observe the changes in biodiversity, we obtained 16S rRNA gene clone libraries from microbial mats at the end of the experiment (eight months) and analyzed them using multivariate and phylogenetic tools. Sequences were assigned to 13 major lineages, among which Cyanobacteria (38.8%) and Alphaproteobacteria (25.5%) were the most abundant. The less extreme treatments (Control and UVmin) had a more similar composition and distribution of the phylogenetic groups with the natural pools than the most extreme treatments (Fluct, 40C, and UVplus), which showed drastic changes in the community composition and structure, indicating a different community response to each environmental disturbance. An increase in bacterial diversity was found in the UVmin treatment, suggesting that protected environments promote the establishment of complex bacterial communities, while stressful environments reduce diversity and increase the dominance of a few Cyanobacterial OTUs (mainly Leptolyngbya sp) through environmental filtering. Mesocosm experiments using complex bacterial communities, along with multivariate and phylogenetic analyses of molecular data, can

  18. Multivariate and phylogenetic analyses assessing the response of bacterial mat communities from an ancient oligotrophic aquatic ecosystem to different scenarios of long-term environmental disturbance.

    Directory of Open Access Journals (Sweden)

    Silvia Pajares

    Full Text Available Understanding the response of bacterial communities to environmental change is extremely important in predicting the effect of biogeochemical modifications in ecosystem functioning. The Cuatro Cienegas Basin is an ancient oasis in the Mexican Chihuahuan desert that hosts a wide diversity of microbial mats and stromatolites that have survived in extremely oligotrophic pools with nearly constant conditions. However, thus far, the response of these unique microbial communities to long-term environmental disturbances remains unexplored. We therefore studied the compositional stability of these bacterial mat communities by using a replicated (3x mesocosm experiment: a Control; b Fluct: fluctuating temperature; c 40C: increase to 40 ºC; d UVplus: artificial increase in UV radiation; and f UVmin: UV radiation protection. In order to observe the changes in biodiversity, we obtained 16S rRNA gene clone libraries from microbial mats at the end of the experiment (eight months and analyzed them using multivariate and phylogenetic tools. Sequences were assigned to 13 major lineages, among which Cyanobacteria (38.8% and Alphaproteobacteria (25.5% were the most abundant. The less extreme treatments (Control and UVmin had a more similar composition and distribution of the phylogenetic groups with the natural pools than the most extreme treatments (Fluct, 40C, and UVplus, which showed drastic changes in the community composition and structure, indicating a different community response to each environmental disturbance. An increase in bacterial diversity was found in the UVmin treatment, suggesting that protected environments promote the establishment of complex bacterial communities, while stressful environments reduce diversity and increase the dominance of a few Cyanobacterial OTUs (mainly Leptolyngbya sp through environmental filtering. Mesocosm experiments using complex bacterial communities, along with multivariate and phylogenetic analyses of molecular

  19. The combined impact of land use change and aquaculture on sediment and water quality in oligotrophic Lake Rupanco (North Patagonia, Chile, 40.8°S).

    Science.gov (United States)

    León-Muñoz, Jorge; Echeverría, Cristian; Marcé, Rafael; Riss, Wolfgang; Sherman, Bradford; Iriarte, Jose Luis

    2013-10-15

    Water and sediment quality in North Patagonia's large, oligotrophic lakes are expected to suffer as native forest continues to be fragmented and degraded by its conversion to cropping and pasture land uses. These changes in land use are expected to increase diffuse nutrient loads to the region's lakes. In addition, these lakes are home to the world's second largest salmon aquaculture industry which provides additional point sources of nutrients within the lakes. We studied the combined influences of land use change and salmon farming on the nutrient concentrations in a North Patagonian lake (Lake Rupanco, 233 km(2) water surface, 163 m average depth) in four sub-watersheds ranging in disturbance from near-pristine forest to 53% converted to cropping and pasture. Nitrogen exports from the tributary sub-watersheds increased from 33 kg TN/km(2)/y to 621 kg TN/km(2)/y as the proportion of crop and pasture land increased. The combined nutrient load from land use change and salmon farming has led to significant differences in the nitrogen concentrations of the lake's water column and sediments in the near-shore zones across the lake. Total nitrogen concentrations in the sediments varied from 37 ± 18 mg/kg in near-pristine sub-watersheds without salmon farming to 6400 ± 698 mg/kg where the sub-watershed was dominated by crop and pasture lands combined with the presence of salmon farming. These results demonstrate the importance of considering the impacts of both salmon farming and land use on water and sediment quality for future environmental planning, management and decision making.

  20. Avaliação da influência de substâncias fenólicas e carotenoides na anomalia do epicarpo da goiaba, "anelamento"

    Directory of Open Access Journals (Sweden)

    Taiji Watanabe

    2011-03-01

    Full Text Available A anomalia do epicarpo da goiaba, comumente relatada por agricultores e técnicos como o "anelamento juvenil da goiaba", tem causado preocupação devido à desinformação sobre o assunto. O objetivo deste estudo foi analisar quimicamente as concentrações de substâncias fenólicas e carotenoides na região do epicarpo de goiabas afetadas pelo "anelamento", visando a caracterizar essa anomalia previamente relatada. Foram analisadas substâncias fenólicas (taninos, flavonas/flavonóis, antocianinas e fenóis totais e carotenoides em epicarpos de frutos verdes e maduros de goiabeiras cv. Paluma, com e sem anomalia. O delineamento experimental adotado foi o inteiramente casualizado, sendo estabelecidos seis tratamentos com o epicarpo dos frutos maduro sem anomalia na região inferior (FMSI; frutos maduros sem injuria na região superior (FMSS; frutos verdes sem anomalia na região inferior (FVSI; frutos verdes sem anomalia na região superior (FVSS; frutos verdes com anomalia na região inferior (FVCI; frutos verdes com anomalia na região superior (FVCS. Dentre as substâncias analisadas, os carotenoides, os taninos e os fenóis totais mostram indicativos para a caracterização do anelamento. Tanto substâncias fenólicas quanto carotenoides apresentam propriedades antioxidantes e, dessa forma, poderiam estar relacionadas à defesa antioxidante causada por um fator de estresse ainda desconhecido, que promove o "anelamento" característico apresentado pelas goiabas.

  1. Composição fenólica de ligninas dioxano determinadas pela reação oxidativa com o nitrobenzeno

    Directory of Open Access Journals (Sweden)

    Fukushima Romualdo Shigueo

    2003-01-01

    Full Text Available A correta quantificação da concentração de lignina em plantas forrageiras, pelo método espectrofotométrico, pressupõe a existência de um padrão de referência. Um padrão de referência deve ter composição fenólica semelhante à da lignina da parede celular. O objetivo deste trabalho foi verificar se ligninas extraídas com solução ácida de dioxano para serem utilizadas como padrão de referência, apresentariam variação na composição fenólica da mesma maneira que a lignina da parede celular. Amostras de parede celular de "bromegrass", milho e trevo-vermelho foram submetidas ao método para extração de ligninas com solução ácida de dioxano. A composição fenólica das ligninas foi analisada mediante oxidação alcalina pelo nitrobenzeno com posterior separação dos componentes monoméricos via HPLC. As ligninas extraídas confirmaram a existência de variação na composição fenólica da mesma maneira às ligninas intactas presentes na parede celular e de substancial presença de ácidos cinâmicos nas ligninas de gramíneas. No que diz respeito à composição fenólica, ligninas extraídas com solução ácida de dioxano podem ser consideradas potenciais padrões de referência paras as análises espectrofotométricas.

  2. Produção de mudas de cultivares de alface utilizando duas espumas fenólicas em Altamira, Pará

    Directory of Open Access Journals (Sweden)

    Alzirio Lino Couto

    2015-06-01

    Full Text Available O sucesso de qualquer produção comercial de hortaliças inicia-se com a produção de mudas. A espuma fenólica tem se mostrado um interessante e prático substrato para este processo. A utilização deste produto depende de uma lavagem precedente para reduzir a acidez. Porém, já é possível encontrar à venda espumas fenólicas com pH próximo. Por isso o objetivo deste trabalho foi avaliar a produção de mudas de cultivares de alface utilizando duas espumas fenólicas em Altamira, Pará. O delineamento constou de um esquema fatorial 2 (substratos x 6 (cultivares. Os dois substratos foram as espumas fenólicas Green Up®, com pH 6.0 (± 0.5., e a outra com pH 2.6 (± 0.5. As cultivares avaliadas foram: Alcione, Amanda, Lucy Brown, Caipira, Multiblond 3 e Solaris. Foi avaliada porcentagem de germinação, índice de velocidade de emergência, altura da planta e número de folhas. Houve diferença significativa para altura da planta em função dos substratos testados. A porcentagem de germinação mais elevada foi obtida com a espuma fenólica sem tratamento. A cultivar Caipira foi a que teve o menor desempenho na germinação. Para todas as variáveis analisadas, a cultivar Lucy Brown apresentou os melhores resultados em ambos os substratos.

  3. Avaliação da atividade antioxidante dos compostos fenólicos naturalmente presentes em subprodutos do pseudofruto de caju (Anacardium occidentale L. Evaluation of the Antioxidant Activity of Phenolic Compounds Naturally Contained in By-products of the Cashew Apple (Anacardium occidentale L.

    Directory of Open Access Journals (Sweden)

    Priscila Regina Bolelli Broinizi

    2007-12-01

    Full Text Available O presente trabalho teve como proposta avaliar a capacidade antioxidante do bagaço e do extrato bruto concentrado (EBC do pedúnculo de caju, tendo em vista o seu aproveitamento. O potencial antioxidante dos extratos aquoso (EAq e alcoólico (EAlc e das frações de ácidos fenólicos livres (AFL e esterificadas (solúvel AFS e insolúvel AFI desses subprodutos do pedúnculo de caju clone CCP-76 foi avaliado em sistema beta-caroteno/ácido linoléico, pelo teste de varredura de radical livre [2,2 difenil-1-pricril-hidrazil (DPPH•] e de Rancimat. Além do mais, o conteúdo de fenólicos totais e o perfil de ácidos fenólicos foram determinados usando-se o reagente de Folin-Ciocateau e por cromatografia gasosa, respectivamente. O EAq e a fração AFL dos subprodutos apresentaram o maior conteúdo de fenólicos. As frações de ácidos fenólicos exibiram expressiva atividade antioxidante, superior aos extratos estudados nos sistemas beta-caroteno e DPPH. Entretanto no teste Rancimat, os extratos apresentaram maior proteção à oxidação em relação às frações e ao BHT. Nas frações foram identificados os ácidos gálico, ferúlico, caféico, protocatecuico, quínico, cinâmico, gentíssico, p-cumárico e salicílico, os quais lhes conferem o potencial antioxidante. Estes resultados caracterizaram in vitro o potencial antioxidante do bagaço e do EBC do pedúnculo de caju clone CCP-76.This study aimed to determine the antioxidant capacity of cashew apple pulp and raw concentrated extract. The antioxidant potential of aqueous (EAq and alcoholic (EAlc extracts and of free phenolic acids (FPA and esterified (soluble - SPA and insoluble - IPA fractions of the by-products of the cashew apple clone CCP-76 were evaluated in a beta-carotene-linoleate system by the free radical [2,2-diphenyl-1-picrylhydrazyl (DPPH•] scavenging assay and the Rancimat test. In addition, the total phenolic content and phenolic acid profile were determined using

  4. La dictadura militar en Grecia (1967- 1974. ¿Cómo enfocar el fenómeno autoritario?

    Directory of Open Access Journals (Sweden)

    Georges D. CONTOGEORGIS

    2010-02-01

    Full Text Available RESUMEN: La Dictadura de los Coroneles es abordada como un fenómeno inherente al déficit democrático, no tanto de la sociedad griega, sino del sistema internacional. El hecho de que la Dictadura Griega se atribuya a valores geoestratégicos y al déficit democrático (p.e. la prohibición del acceso al poder de los partidos políticos no liberales de los líderes de la Guerra Fría está también en sintonía con la diferencia fundamental que lo distingue de las dictaduras de la Península Ibérica. Estas últimas están relacionadas con un mismo fenómeno anterior de la Europa anterior a la Segunda Guerra Mundial y como tales están clasificadas como una parte del proceso de transición que tuvo lugar en el Viejo Continente. Por el contrario, el fenómeno autoritario en el sistema político griego constituye un paréntesis porque la sociedad griega no experimentó la transición del feudalismo a la modernidad y su sistema político fue desde el comienzo (desde 1821 el primero entre los estados-nación con una base representativa asentada sobre el sufragio universal. Todo ello demuestra que las distinciones entre Norte y Sur, relativas a la democracia, están ideológicamente condicionadas y no derivan de conclusiones extraídas del desarrollo político de las sociedades. Palabras clave: Totalitarismo, Dictadura, Déficit democrático, Estado representativo, Guerra Fría, Protesta, Consenso político. ABSTRACT: The Dictatorship of the Colonels is approached as a phenomenon, which is inherent in the democratic deficit, not of Greek society, but of the international system. The fact that the Greek Dictatorship is attributed to geostrategic reasons and to the democratic deficit (e.g. the prohibition of access to power of non-liberal political parties of the leaders of the Cold War is also in line with the fundamental difference, which distinguishes it from dictatorships of the Iberian Peninsula. The latter are related to the same phenomena of

  5. Fenólicos e carotenóides totais em pitanga Total phenolics and carotenoids in surinam cherry

    Directory of Open Access Journals (Sweden)

    Vera Lúcia Arroxelas Galvão de Lima

    2002-09-01

    Full Text Available Em decorrência de uma ampla diversidade genética, a pitanga (Eugenia uniflora L. apresenta cor que varia do alaranjado até o vermelho escuro quase negro. Em Pernambuco, no entanto, é comum encontrá-la com coloração laranja-avermelhada. Como muitos fitoquímicos presentes em frutos exibem propriedades antioxidantes, com destaque para carotenóides e compostos fenólicos, e frente a escassez de informações sobre seus teores em pitanga, objetivou-se quantificá-los nas seleções cujos frutos apresentam coloração vermelha e roxa. Assim, foram determinados espectrofotometricamente os teores de carotenóides e fenólicos totais nos frutos destas seleções nos estádios maduro e semi-maduro. Na pitanga roxa madura e em sua película também foram determinados os teores de antocianinas, flavonóis e carotenóides totais. Os compostos fenólicos e os carotenóides totais na pitanga roxa madura encontram-se em maiores teores do que na pitanga vermelha no mesmo estádio de maturação. A seleção roxa exibiu quantidade significante de antocianinas, cujo teor foi mais elevado no fruto maduro do que no semi-maduro. Os carotenóides, antocianinas e flavonóis encontram-se mais concentrados na película do que na polpa deste fruto maduro. A presença de antocianinas, flavonóis e carotenóides totais na pitanga roxa fazem deste fruto uma fonte promissora de compostos antioxidantes cujo cultivo deveria ser estimulado.Because of the genetic diversity, fruits of Surinam cherry (Eugenia uniflora L. show colours that range from orange to deep, almost dark red. However, in Pernambuco, Brazil, it is common to find this fruit with an orange-red colour. Many phytochemicals in fruits have antioxidant properties with emphasis on phenolic compounds and carotenoids. Since the information on these phytochemicals in surinam cherry is scarce, the aim of this research was to analyse them in fruits which show red and purple colours. Half-mature and mature fruits

  6. Effects of N and P fertilisation on greenhouse gas (GHG) production in floodplain fen peat: A microcosm fertilisation experiment.

    Science.gov (United States)

    Stanley, Kieran; Heppell, Catherine; Belyea, Lisa; Baird, Andrew

    2016-04-01

    Biogeochemical and hydrological cycles are being significantly perturbed by anthropic activities altering atmospheric mole fractions of greenhouse gases (GHG) and increasing global temperatures. With the intensification of the hydrological cycle, lowland areas, such as floodplain fens, may be inundated more frequently. Rivers in agricultural catchments have the potential to pollute floodplain fens with significant amounts of nitrogen (N) and phosphorus (P); however, the effects of short-term (control, glucose (G), N+G, P+G, and N+P+G), fully-factorial microcosm experiment was designed and undertaken in Spring 2013 with peat from two floodplain fens under conservation management with similar vegetation (from Norfolk, United Kingdom). One site receives a higher nutrient load than the other and has a historical legacy of higher N and P contents within the peat. Results from the experiment showed no significant difference in CO2 production between the control and fertilised treatments from 0 to 96 hours, but a significant difference between treatments (ANCOVA, between factors: treatment and site; covariate: time; F4,419 = 11.844, p < 0.001) and site (F1,149 = 5.721, p = 0.017) from 96 hours to in the end of the experiment due to fermentation. N2O production only occurred in samples fertilised with N (N+G and N+P+G) due to denitrification. Rates of N2O production were significantly greater in samples from the lower-nutrient site in comparison to the nutrient-rich site (t12= 6.539, p < 0.001 and t12= 7.273, p < 0.001 for N+G and N+P+G fertilised samples, respectively). Fertilisation with N and P had different effects on CH4 production. Samples fertilised with P+G had the highest CH4 production (ANCOVA, between factors: treatment and site; covariate: time; F4,120= 15.026, p < 0.001). Samples fertilised with N (N+G and N+P+G) showed CH4 inhibition in comparison to G and P+G additions. CH4 production was significantly greater from the nutrient-rich peat than from the lower

  7. Uranium entrapment in wetlands: A case study at the Boston Peak fen, Colorado, U.S.A

    International Nuclear Information System (INIS)

    The Boston Peak fen, a 5-hectare, uranium-enriched wetland located northwest of Rocky Mountain National Park in northern Colorado, has been the subject of intensive study by U.S. Geological Survey scientists through surface mapping, drilling, and sampling of an extensive network of 59 auger and core holes. Uranium concentrations increased dramatically in the organic-rich gyttja (50-150 ppm) compared to the lower lakebeds (4-70 ppm). The uranium in the gyttja is stratabound, and variations in uranium content between sediment layers could be caused by differences in supply of dissolved uranium to the lake and differences in sediment redox conditions. Uranium concentrations in the gyttja drop before the transition to peat, except in lake sediment near spring or seep sources, despite the constant or increasing organic matter content of the gyttja. Dissolved uranium delivered by spring water was now locally fixed by peat adjacent to the spring pools, resulting in uranium concentrations of as much as 4,000 ppm (dry weight) whereas peat distant from spring pools may have only a few ppm of uranium. Water chemistry and uranium in peat are discussed. Studies of this wetland confirm the well-documented observation that wetlands serve as natural filters for uranium and many other potentially hazardous trace elements that may otherwise enter downstream surface waters. Inadvertent or deliberate destruction of metalbearing wetlands may diminish water quality and remove the potential for continued filtering activity. The processes affecting uranium transport, sorption, and ultimate fixation in the peat may have relevance for understanding uranium-organic associations in ore deposits in the major sandstone uranium districts of the San Juan Basin and elsewhere. Stratabound uranium in the gyttja may serve as an analogue of much older uranium- and organic-matter-rich systems such as the massive low-grade lacustrine uranium deposits of late Tertiary age in some western Arizona basins

  8. Işık ünitesinde similasyon yönteminin kullanılmasının öğrencilerin Fen başarısına ve Fen tutumlarına etkisi

    OpenAIRE

    Küçük, Taner

    2014-01-01

    Bu tez çalışmasında, bilgisayar ortamında gerçek durumların birebir oluşturulmasını sağlayan simülasyon yönteminin öğrenci başarısına ve tutumuna etkisi incelenmiştir. Çalışmanın evren ve örneklemi Çanakkale ili Kepez ilçesi Mehmet Akif Ersoy Ortaokulu 7.sınıfta öğrenim gören 98 öğrencidir. Deney grubu olarak 7/A ve 7/C sınıflarından toplam 52 öğrenci, kontrol grubu olaraksa 7/B ve 7/D sınıflarından toplam 46 öğrenci seçilmiştir. Öntest sontest kontrol gruplu desen kullanılan araştırmada, fen...

  9. Antioxidant activity and phenolic content of agricultural by-products from wine production/ Atividade antioxidante e conteúdo fenólico do resíduo agroindustrial da produção de vinho

    Directory of Open Access Journals (Sweden)

    Eugênia Marta Kuskoski

    2008-08-01

    Full Text Available The present work aimed to investigate the antioxidant properties of byproducts derived from wine production. The varieties of PINOT GRIS and COUDERC 13 grapes, collected in Videira-SC, were analyzed as natural sources of polyphenols and other prophylactic agents (antioxidants for application in food and phytochemical industries. The biomass used for extracts was ground and dried in different temperatures (45oC, 60oC e 80oC, using acetone 80% as solvent. The phenolic compounds were quantitatively evaluated by the Folin-Ciocalteu method and the results expressed in mg/100g of Gallic acid. For the flavonoids analysis, it was applied DMACA (p- Dimethylaminocinnamaldehye method and the results were expressed in equivalent mg of catechin/100g sample. The antioxidant activity was evaluated by spectrophotometric method through the discoloration of ABTS•+ radical (2,2'-azino-bis[3- ethylbenzthiazoline-6-sulfonic acid] with potassium persulphate and by DPPH method, which is based on the reduction of DPPH• radical absorbance by antioxidant substances; the results were expressed in TEAC (antioxidant activity equivalent to Trolox and VCEAC (antioxidant activity equivalent to vitamin C. It was observed a better antioxidant activity on extracts obtained from PINOT GRIS grapes, in which the 45 oC dried extracts presented a higher number of phenolic compounds and flavonoids, as well as a better antioxidant activity in both varieties. These information become useful for phenolic compounds identifying and for a possible using of these extracts as a secure additive in food industry.Este trabalho propõe uma investigação do potencial antioxidante do resíduo no processamento de uvas das variedades COUDERC 13 e PINOT GRIS, ambas coletadas em Videira-SC, como fonte natural de polifenóis e outros agentes profiláticos (antioxidantes para aplicação nas indústrias alimentícia e de fitoterápicos. A biomassa utilizada para obtenção dos extratos foi triturada

  10. Contribution and pathways of diazotroph-derived nitrogen to zooplankton during the VAHINE mesocosm experiment in the oligotrophic New Caledonia lagoon

    Science.gov (United States)

    Hunt, Brian P. V.; Bonnet, Sophie; Berthelot, Hugo; Conroy, Brandon J.; Foster, Rachel A.; Pagano, Marc

    2016-05-01

    In oligotrophic tropical and subtropical oceans, where strong stratification can limit the replenishment of surface nitrate, dinitrogen (N2) fixation by diazotrophs can represent a significant source of nitrogen (N) for primary production. The VAHINE (VAriability of vertical and tropHIc transfer of fixed N2 in the south-wEst Pacific) experiment was designed to examine the fate of diazotroph-derived nitrogen (DDN) in such ecosystems. In austral summer 2013, three large ( ˜ 50 m3) in situ mesocosms were deployed for 23 days in the New Caledonia lagoon, an ecosystem that typifies the low-nutrient, low-chlorophyll environment, to stimulate diazotroph production. The zooplankton component of the study aimed to measure the incorporation of DDN into zooplankton biomass, and assess the role of direct diazotroph grazing by zooplankton as a DDN uptake pathway. Inside the mesocosms, the diatom-diazotroph association (DDA) het-1 predominated during days 5-15 while the unicellular diazotrophic cyanobacteria UCYN-C predominated during days 15-23. A Trichodesmium bloom was observed in the lagoon (outside the mesocosms) towards the end of the experiment. The zooplankton community was dominated by copepods (63 % of total abundance) for the duration of the experiment. Using two-source N isotope mixing models we estimated a mean ˜ 28 % contribution of DDN to zooplankton nitrogen biomass at the start of the experiment, indicating that the natural summer peak of N2 fixation in the lagoon was already contributing significantly to the zooplankton. Stimulation of N2 fixation in the mesocosms corresponded with a generally low-level enhancement of DDN contribution to zooplankton nitrogen biomass, but with a peak of ˜ 73 % in mesocosm 1 following the UCYN-C bloom. qPCR analysis targeting four of the common diazotroph groups present in the mesocosms (Trichodesmium, het-1, het-2, UCYN-C) demonstrated that all four were ingested by copepod grazers, and that their abundance in copepod

  11. Complexity of diatom response to Lateglacial and Holocene climate and environmental change in ancient, deep, and oligotrophic Lake Ohrid (Macedonia/Albania)

    Science.gov (United States)

    Zhang, X. S.; Reed, J. M.; Lacey, J. H.; Francke, A.; Leng, M. J.; Levkov, Z.; Wagner, B.

    2015-09-01

    Lake Ohrid (Macedonia/Albania) is a rare example of a deep, ancient Mediterranean lake and is a key site for palaeoclimate research in the northeastern Mediterranean region. This study conducts the first high-resolution diatom analysis during the Lateglacial and Holocene in Lake Ohrid. It demonstrates a complex diatom response to temperature change, with a direct response to temperature-induced productivity and an indirect response to temperature-related stratification/mixing regime and epilimnetic nutrient availability. During the Lateglacial (ca. 12 300-11 800 cal yr BP), the low-diversity dominance of hypolimnetic Cyclotella fottii indicates low temperature-dependent lake productivity. During the earliest Holocene (ca. 11 800-10 600 cal yr BP), although the slight increase in small, epilimnetic C. minuscula suggests climate warming and enhanced thermal stratification, diatom concentration remains very low as during the Lateglacial, indicating that temperature increase was muted. The early Holocene (ca. 10 600-8200 cal yr BP) marked a sustained increase in epilimnetic taxa, with mesotrophic C. ocellata indicating high temperature-induced lake productivity between ca. 10 600-10 200 cal yr BP and between ca. 9500-8200 cal yr BP, and with C. minuscula in response to low nutrient availability in the epilimnion between ca. 10 200-9500 cal yr BP. During the mid Holocene (ca. 8200-2600 cal yr BP), when sedimentological and geochemical proxies provide evidence for high temperature, anomalously low C. ocellata abundance is probably a response to epilimnetic nutrient limitation, almost mimicking the Lateglacial flora apart from mesotrophic Stephanodiscus transylvanicus indicative of high temperature-induced productivity in the hypolimnion. During the late Holocene (ca. 2600-0 cal yr BP), high abundance and fluctuating composition of epilimnetic taxa is largely a response to enhanced anthropogenic nutrient input. In this deep, oligotrophic lake, this study demonstrates the

  12. Complexity of diatom response to Lateglacial and Holocene climate and environmental change in ancient, deep, and oligotrophic Lake Ohrid (Macedonia/Albania

    Directory of Open Access Journals (Sweden)

    X. S. Zhang

    2015-09-01

    Full Text Available Lake Ohrid (Macedonia/Albania is a rare example of a deep, ancient Mediterranean lake and is a key site for palaeoclimate research in the northeastern Mediterranean region. This study conducts the first high-resolution diatom analysis during the Lateglacial and Holocene in Lake Ohrid. It demonstrates a complex diatom response to temperature change, with a direct response to temperature-induced productivity and an indirect response to temperature-related stratification/mixing regime and epilimnetic nutrient availability. During the Lateglacial (ca. 12 300–11 800 cal yr BP, the low-diversity dominance of hypolimnetic Cyclotella fottii indicates low temperature-dependent lake productivity. During the earliest Holocene (ca. 11 800–10 600 cal yr BP, although the slight increase in small, epilimnetic C. minuscula suggests climate warming and enhanced thermal stratification, diatom concentration remains very low as during the Lateglacial, indicating that temperature increase was muted. The early Holocene (ca. 10 600–8200 cal yr BP marked a sustained increase in epilimnetic taxa, with mesotrophic C. ocellata indicating high temperature-induced lake productivity between ca. 10 600–10 200 cal yr BP and between ca. 9500–8200 cal yr BP, and with C. minuscula in response to low nutrient availability in the epilimnion between ca. 10 200–9500 cal yr BP. During the mid Holocene (ca. 8200–2600 cal yr BP, when sedimentological and geochemical proxies provide evidence for high temperature, anomalously low C. ocellata abundance is probably a response to epilimnetic nutrient limitation, almost mimicking the Lateglacial flora apart from mesotrophic Stephanodiscus transylvanicus indicative of high temperature-induced productivity in the hypolimnion. During the late Holocene (ca. 2600–0 cal yr BP, high abundance and fluctuating composition of epilimnetic taxa is largely a response to enhanced anthropogenic nutrient input. In this deep, oligotrophic lake

  13. Short-term dynamics of nutrients influenced by upwelling in a small oligotrophic coastal ecosystem,Gan Bay,in the northwest Philippines

    Institute of Scientific and Technical Information of China (English)

    Yanping Xu; Minhan Dai; Weidong Zhai; Dongxing Yuan; Jinwen Liu; Zhenyu Sun; Hua Lin; Jingyu Wi

    2009-01-01

    We present a time-series analysis of nutrient and pCO2 (partial pressure of CO2) levels in an oligotrophic coastal ecosystem (Gan Bay),which was likely to be influenced by upwelled subsurface water.Gan Bay is off Currimao Harbor,in the northwest Philippines and is located at the boundary of the South China Sea (SCS).This 42-h time-series observation was conducted in December 2006.In addition to continuous observations of dissolved oxygen (DO) and pCO2,discrete samples were collected at a depth of 5 m every 3 h for measurements of nutrients,including soluble reactive phosphorus (SRP) and inorganic nitrogen (NO3- + NO2-) in order to examine their dynamics and possible physical and biological controls.We observed remarkably large short-term variations in the surface water,spanning a 10-fold change for SRP (32-330 nM) and from <0.3 μM to 4.3 μM for NO3- + NO2-.DO also varied substantially from a lower end of 171 to 205 μM O2.Surface water pCO2 changed from an equilibrium stage with the atmosphere (~386 μatm) to a stage where it was a significant source for the atmospheric CO2 (seawater pCO2~469 μatm).We found that the variation of nutrients was driven neither by tidal mixing nor by biological activities,as was suggested by the variations in the total bacterial abundance and chlorophyll a.Instead,our inverse T-S relationship suggested a two end-member mixing process during the observation period.The N:P ratio throughout the observation period was ~13.2,which is characteristic of SCS subsurface and deep waters.Moreover,pCO2 was correlated inversely with the sea surface temperature.It is likely,therefore,that an upwelled subsurface cold water with high nutrients,low-temperature and high-pCO2 existed.It should be noted that this upwelled cold water did not appear to impact the entire observation period (approximately 35 h of 42 h),which might suggest an extremely dynamic nature for this upwelled cold water mass.(C) 2009 National Natural Science Foundation of

  14. Stability of toxin gene proportion in red-pigmented populations of the cyanobacterium Planktothrix during 29 years of re-oligotrophication of Lake Zürich

    Directory of Open Access Journals (Sweden)

    Ostermaier Veronika

    2012-12-01

    Full Text Available Abstract Background Harmful algal blooms deteriorate the services of aquatic ecosystems. They are often formed by cyanobacteria composed of genotypes able to produce a certain toxin, for example, the hepatotoxin microcystin (MC, but also of nontoxic genotypes that either carry mutations in the genes encoding toxin synthesis or that lost those genes during evolution. In general, cyanobacterial blooms are favored by eutrophication. Very little is known about the stability of the toxic/nontoxic genotype composition during trophic change. Results Archived samples of preserved phytoplankton on filters from aquatic ecosystems that underwent changes in the trophic state provide a so far unrealized possibility to analyze the response of toxic/nontoxic genotype composition to the environment. During a period of 29 years of re-oligotrophication of the deep, physically stratified Lake Zürich (1980 to 2008, the population of the stratifying cyanobacterium Planktothrix was at a minimum during the most eutrophic years (1980 to 1984, but increased and dominated the phytoplankton during the past two decades. Quantitative polymerase chain reaction revealed that during the whole observation period the proportion of the toxic genotype was strikingly stable, that is, close to 100%. Inactive MC genotypes carrying mutations within the MC synthesis genes never became abundant. Unexpectedly, a nontoxic genotype, which lost its MC genes during evolution, and which could be shown to be dominant under eutrophic conditions in shallow polymictic lakes, also co-occurred in Lake Zürich but was never abundant. As it is most likely that this nontoxic genotype contains relatively weak gas vesicles unable to withstand the high water pressure in deep lakes, it is concluded that regular deep mixing selectively reduced its abundance through the destruction of gas vesicles. Conclusions The stability in toxic genotype dominance gives evidence for the adaptation to deep mixing of a

  15. On-Orbit Geometric Calibration Approach for High-Resolution Geostationary Optical Satellite GaoFen-4

    Science.gov (United States)

    Wang, Mi; Cheng, Yufeng; Long, Xiaoxiang; Yang, Bo

    2016-06-01

    The GaoFen-4 (GF-4) remote sensing satellite is China's first civilian high-resolution geostationary optical satellite, which has been launched at the end of December 2015. To guarantee the geometric quality of imagery, this paper presents an on-orbit geometric calibration method for the area-array camera of GF-4. Firstly, we introduce the imaging features of area-array camera of GF-4 and construct a rigorous imaging model based on the analysis of the major error sources from three aspects: attitude measurement error, orbit measurement error and camera distortion. Secondly, we construct an on-orbit geometric calibration model by selecting and optimizing parameters of the rigorous geometric imaging model. On this basis, the calibration parameters are divided into two groups: external and internal calibration parameters. The external parameters are installation angles between the area-array camera and the star tracker, and we propose a two-dimensional direction angle model as internal parameters to describe the distortion of the areaarray camera. Thirdly, we propose a stepwise parameters estimation method that external parameters are estimated firstly, then internal parameters are estimated based on the generalized camera frame determined by external parameters. Experiments based on the real data of GF-4 shows that after on-orbit geometric calibration, the geometric accuracy of the images without ground control points is significantly improved.

  16. El análisis discursivo de fenómenos de violencia en un corpus de prensa digital

    Directory of Open Access Journals (Sweden)

    Carmen Ávila Martín

    2014-08-01

    Full Text Available Normal 0 21 false false false ES X-NONE X-NONE El análisis del discurso mediático dispone en la actualidad de herramientas que proporcionan análisis empíricos cuantitativamente más documentados que los análisis tradicionales. El análisis léxico de las coocurrencias discursivas aporta datos de interés para interpretar cómo se construyen los discursos. Nuestro interés se sitúa en el empleo de la Lingüística de Corpus como instrumento para el Análisis del Discurso, pues ambas disciplinas presentan en la actualidad metodología adecuada para la interpretación de discursos como auxiliares en el análisis e interpretación de determinados fenómenos significativos. Para ello utilizaremos corpus específicos que nos aportan datos sobre la utilización discursiva de las unidades analizadas. Nos detendremos en determinadas manifestaciones de violencia en textos periodísticos que tienen denominaciones específicas en inglés y en español, no siempre coincidentes.

  17. Methane dynamics in an alpine fen: a field-based study on methanogenic and methanotrophic microbial communities.

    Science.gov (United States)

    Franchini, Alessandro G; Henneberger, Ruth; Aeppli, Meret; Zeyer, Josef

    2015-03-01

    Wetlands are important sources of the greenhouse gas methane (CH4). We provide an in situ study of CH4 dynamics in the permanently submerged soil of a Swiss alpine fen. Physico-chemical pore water analyses were combined with structural and microbiological analyses of soil cores at high vertical resolution down to 50 cm depth. Methanotrophs and methanogens were active throughout the depth profile, and highest abundance of active methanotrophs and methanogens [6.1 × 10(5) and 1.1 × 10(7) pmoA and mcrA transcripts (g soil)(-1), respectively] was detected in the uppermost 2 cm of the soil. Active methanotrophic communities in the near-surface zone, dominated by viable mosses, varied from the communities in the deeper zones, but further changes with depth were not pronounced. Apart from a distinct active methanogenic community in the uppermost sample, a decrease of acetoclastic Methanosaetaceae with depth was observed in concomitance with decreasing root surface area. Overall, root surface area correlated with mcrA transcript abundance and CH4 pore water concentrations, which peaked (137.1 μM) at 10 to 15 cm depth. Our results suggest that stimulation of methanogenesis by root exudates of vascular plants had a stronger influence on CH4 dynamics than stimulation of CH4 oxidation by O2 input. PMID:25789997

  18. Annual balances of CH4 and N2O from a managed fen meadow using eddy covariance flux measurements

    International Nuclear Information System (INIS)

    Annual terrestrial balances of methane (CH4) and nitrous oxide (N2O) are presented for a managed fen meadow in the Netherlands for 2006, 2007 and 2008, using eddy covariance (EC) flux measurements. Annual emissions derived from different methods are compared. The most accurate annual CH4 flux is achieved by gap filling EC fluxes with an empirical multivariate regression model, with soil temperature and mean wind velocity as driving variables. This model explains about 60% of the variability in observed daily CH4 fluxes. Annual N2O emissions can be separated into background emissions and event emissions due to fertilization. The background emission is estimated using a multivariate regression model also based on EC flux data, with soil temperature and mean wind velocity as driving variables. The event emissions are estimated using emission factors. The minimum direct emission factor is derived for six fertilization events by subtracting the background emission, and the IPCC default emission factor of 1% is used for the other events. In addition, the maximum direct emission factors are determined for the six events without subtracting the background emission. The average direct emission factor ranges from 1.2 to 2.8%, which is larger than the IPCC default value. Finally, the total terrestrial greenhouse gas balance is estimated at 16 Mg ha-1 year-1 in CO2-equivalents with contributions of 30, 25 and 45% by CO2, CH4 and N2O, respectively.

  19. Acciones gubernamentales frente a los desastres provocados por fenómenos hidrometeorológicos en México

    Directory of Open Access Journals (Sweden)

    Gabriel Angelotti Pasteur

    2015-02-01

    Full Text Available Las acciones realizadas tras los desastres constituyen una oportunidad para el cambio social, en específico, para construir sociedades resilientes. Sin embargo, cuando en los procesos de reconstrucción se persiguen intereses exógenos (económicos, sociales o políticos y, preferentemente, ajenos a las necesidades de la sociedad afectada, se incrementan las condiciones de riesgo y la vulnerabilidad ante futuras amenazas. En el presente trabajo se analiza lo ocurrido en Yucatán (México cuando, tras el paso del huracán Isidoro (2002, se implementó un programa de reconstrucción con el fin de suplir aquellas viviendas que habían sido dañadas y destruidas por ese fenómeno hidrometeorológico. Mediante el mismo se esperaba dotar a las familias damnificadas de una vivienda digna, resistente, moderna y, de este modo, contribuir a forjar una sociedad más segura. Sin embargo, los resultados alcanzados ponen en duda esta meta del gobierno.

  20. Compostos fenólicos e atividade antioxidante de Leiothrix flavescens (Bong. Ruhland (Eriocaulaceae

    Directory of Open Access Journals (Sweden)

    M. A. SILVA

    2009-01-01

    Full Text Available

    O presente estudo químico foi realizado com extrato metanólico de Leiothrix flavescens (Bong. Ruhland (Eriocaulaceae por HSCCC. Fracionamento do extrato metanólico dos capítulos de L. flavescens por métodos cromatográficos preparativos e identificação das substâncias isoladas por (IV, UV, RMN forneceu as flavonas apigenina, luteolina e 6-metoxiluteolina e o 1,3-di-Oferuloilglicerol. O extrato metanólico de L. flavescens foi avaliado quanto à sua atividade antioxidante utilizando- se o reagente de DPPH, enquanto que a quantificação de fenóis totais foi determinada utilizando-se o reagente de Folin-Ciocalteau. Os resultados evidenciaram que o extrato metanólico dos capítulos L. flavescens possui uma significativa atividade antioxidante. Estes resultados permitiram aprofundar a discussão taxonômica da família Eriocaulaceae. Palavras-chave: Eriocaulaceae; Leiothrix; HSCCC; atividade antioxidante.

  1. Estudio exploratorio sobre el fenómeno del “Bullying” en la ciudad de Cali, Colombia

    Directory of Open Access Journals (Sweden)

    María Teresa Paredes

    2008-05-01

    Full Text Available Este es el primer estudio sobre el fenómeno del hostigamiento entre pares o “bullying” que se realiza en la ciudad de Cali, Colombia. Se efectuaron 2.542 encuestas a estudiantes de sexto, séptimo y octavo grados de catorce colegios de la ciudad, con el fin de identificar la presencia del problema y –en caso de existir– de establecer las formas específicas de manifestación, teniendo en cuenta edad, género y estrato socioeconómico.Los resultados demostraron la presencia de “bullying” en el 24.7% de los encuestados y encuestadas, expresado en comportamientos de intimidación o agresión verbal, física y psicológica en estudiantes de ambos géneros de todos los estratos socioeconómicos. Se estableció que la forma de agresión de mayor frecuencia es la verbal y que ésta sucede también en presencia de otros compañeros, compañeras, profesoras y profesores en el aula de clase.

  2. Water level, vegetation composition and plant productivity explain greenhouse gas fluxes in temperate cutover fens after inundation

    Directory of Open Access Journals (Sweden)

    M. Minke

    2015-10-01

    Full Text Available Rewetting of temperate continental cutover peatlands generally implies the creation of flooded areas, which are – dependent on water depth – colonized by helophytes such as Eriophorum angustifolium, Carex spp., Typha latifolia or Phragmites australis. Reeds of Typha and Phragmites are reported to be large sources of methane, but data on net CO2 uptake are contradictory for Typha and rare for Phragmites. This paper describes the effect of vegetation, water level and nutrient conditions on greenhouse gas (GHG emissions for representative vegetation types along water level gradients at two rewetted cutover fens (mesotrophic and eutrophic in Belarus. Greenhouse emissions were measured with manual chambers in weekly to few – weekly intervals over a two years period and interpolated by modelling. All sites had negligible nitrous oxide exchange rates. Most sites were carbon sinks and small GHG sources. Methane emissions were generally associated with net ecosystem CO2 uptake. Small sedges were minor methane emitters and net CO2 sinks, while Phragmites australis sites released large amounts of methane and sequestered very much CO2. Variability of both fluxes increased with site productivity. Floating mats composed of Carex tussocks and Typha latifolia were a source for both methane and CO2. We conclude that shallow, stable flooding is a better measure to arrive at low GHG emissions than deep flooding, and that the risk of high GHG emissions consequent on rewetting is larger for eutrophic than for mesotrophic peatlands.

  3. Hacia una caracterización psico-social del fenómeno de callejerización

    Directory of Open Access Journals (Sweden)

    Elvia Taracena Ruiz

    2010-01-01

    Full Text Available En este artículo realizo una reflexión crítica de mis investigaciones durante 20 años de trabajo con jóvenes y niños en situación de calle. Pongo el énfasis en la definición de la problemática en la articulación de tres registros: macro, medio y micro. Describo el marco teórico-metodológico en donde planteo la necesidad de construir un marco multireferencial y transdisciplinario.Cuestiono la relación del sujeto investigador con el problema estudiado y señalo la importancia del análisis de su implicación. Describo las condiciones sociales que propician la salida a la calle de los jóvenes y las jóvenes, y analizo las consecuencias en el sujeto joven en proceso de callejerización del desarrollo del mercado humanitario. Pongo el énfasis en la construcción de un marco teórico- metodológico buscando respetar tanto la singularidad como complejidad del fenómeno a través de una aproximación cualitativa.

  4. Fenómenos fisiopatológicos sistémicos asociados al bruxismo de sueño

    Directory of Open Access Journals (Sweden)

    V. Iturriaga

    2014-12-01

    Full Text Available El bruxismo de sueño (BS se define como un trastorno del movimiento estereotipado que se presenta durante el sueño, caracterizado por rechinamiento y/o apretamiento dentario. Se encuentra dentro de la clasificación internacional de desórdenes de sueño como un trastorno del movimiento asociado a una exagerada actividad muscular masticatoria rítmica. Se reporta una incidencia del 15% al 22% en la población general. Antiguamente se creía que la etiología del BS estaba relacionada con alteraciones oclusales; sin embargo actualmente se piensa que la causa principal está más bien relacionada con alteraciones de sueño, enfermedades del sistema nervioso central, drogas, dolor crónico, alteraciones emocionales, entre otros factores que participarían en su origen. Se ha identificado la presencia de diversos fenómenos fisiopatológicos sistémicos que acontecen durante un episodio de BS, entre los cuales encontramos los microdespertares corticales, alteraciones en el ritmo cardíaco, el tono simpático, la presión arterial, entre otros, sobre los cuales trata esta revisión.

  5. Response of plant community structure and primary productivity to experimental drought and flooding in an Alaskan fen

    Science.gov (United States)

    Churchill, A.C.; Turetsky, Merritt R.; McGuire, Anthony; Hollingsworth, Teresa N.

    2014-01-01

    Northern peatlands represent a long-term net sink for atmospheric CO2, but these ecosystems can shift from net carbon (C) sinks to sources based on changing climate and environmental conditions. In particular, changes in water availability associated with climate control peatland vegetation and carbon uptake processes. We examined the influence of changing hydrology on plant species abundance and ecosystem primary production in an Alaskan fen by manipulating the water table in field treatments to mimic either sustained flooding (raised water table) or drought (lowered water table) conditions for 6 years. We found that water table treatments altered plant species abundance by increasing sedge and grass cover in the raised water table treatment and reducing moss cover while increasing vascular green area in the lowered water table treatment. Gross primary productivity was lower in the lowered treatment than in the other plots, although there were no differences in total biomass or vascular net primary productivity among the treatments. Overall, our results indicate that vegetation abundance was more sensitive to variation in water table than total biomass and vascular biomass accrual. Finally, in our experimental peatland, drought had stronger consequences for change in vegetation abundance and ecosystem function than sustained flooding.

  6. Measurement and modelling of CO2 flux from a drained fen peatland cultivated with reed canary grass and spring barley

    DEFF Research Database (Denmark)

    Kandel, Tanka Prasad; Elsgaard, Lars; Lærke, Poul Erik

    2013-01-01

    peatland grown with reed canary grass (RCG) and spring barley (SB) in a plot experiment (n = 3 for each cropping system). The CO2flux was partitioned into gross photosynthesis (GP) and ecosystem respiration (RE). For the data analysis, simple yet useful GP and RE models were developed which introduce plot......Cultivation of bioenergy crops has been suggested as a promising option for reduction of greenhouse gas (GHG) emissions from arable organic soils (Histosols). Here, we report the annual net ecosystem exchange (NEE) fluxes of CO2 as measured with a dynamic closed chamber method at a drained fen......-scale ratio vegetation index as an active vegetation proxy. The GP model captures the effect of temperature and vegetation status, and the RE model estimates the proportion of foliar biomass dependent respiration (Rfb) in the total RE. Annual RE was 1887 ± 7 (mean ± standard error, n = 3) and 1288 ± 19 g CO2...

  7. The c/a Ratio in Quenched Fe-C and Fe-N steels - a Heuristic Story

    Energy Technology Data Exchange (ETDEWEB)

    Sherby, O; Wadsworth, J; Lesuer, D; Syn, C

    2006-01-31

    The body-centered tetragonal (BCT) structure in quenched Fe-C steels is usually illustrated to show a linear change in the c and a axes with an increase in carbon content from 0 to 1.4%C. The work of Campbell and Fink, however, shows that this continuous linear relationship is not correct. Rather, it was shown that the body-centered-cubic (BCC) structure is the stable structure from 0 to 0.6 wt%C with the c/a ratio equal to unity. An abrupt change in the c/a ratio to 1.02 occurs at 0.6 wt%C. The BCT structure forms, and the c/a ratio increases with further increase in carbon content. An identical observation is noted in quenched Fe-N steels. This discontinuity is explained by a change in the transformation process. It is proposed that a two-step transformation process occurs in the low carbon region, with the FCC first transforming to HCP and then from HCP to BCC. In the high carbon region, the FCC structure transforms to the BCT structure. The results are explained with the Engel-Brewer theory of valence and crystal structure of the elements. An understanding of the strength of quenched iron-carbon steels plays a key role in the proposed explanation of the c/a anomaly based on interstitial solutes and precipitates.

  8. Fen (n=1–6) clusters chemisorbed on vacancy defects in graphene: Stability, spin-dipole moment, and magnetic anisotropy

    KAUST Repository

    Haldar, Soumyajyoti

    2014-05-09

    In this work, we have studied the chemical and magnetic interactions of Fen (n=1–6) clusters with vacancy defects (monovacancy to correlated vacancies with six missing C atoms) in a graphene sheet by ab initio density functional calculations combined with Hubbard U corrections for correlated Fe-d electrons. It is found that the vacancy formation energies are lowered in the presence of Fe, indicating an easier destruction of the graphene sheet. Due to strong chemical interactions between Fe clusters and vacancies, a complex distribution of magnetic moments appear on the distorted Fe clusters which results in reduced averaged magnetic moments compared to the free clusters. In addition to that, we have calculated spin-dipole moments and magnetic anisotropy energies. The calculated spin-dipole moments arising from anisotropic spin density distributions vary between positive and negative values, yielding increased or decreased effective moments. Depending on the cluster geometry, the easy axis of magnetization of the Fe clusters shows in-plane or out-of-plane behavior.

  9. Atividade antimicrobiana de derivados fenólicos do líquen Ramalina sorediosa (B. de Lesd. Laundron Antimicrobian activity of phenols actives from the liquen Ramalina sorediosa (B. de Lesd. Laundron

    Directory of Open Access Journals (Sweden)

    Emerson P. da Silva Falcão

    2004-12-01

    Full Text Available A atividade antimicrobiana de extratos brutos de Ramalina sorediosa foi detectada pelo método de difusão em disco de papel. Dois metabólitos liquênicos de natureza fenólica foram identificados por meio de técnicas biocromatográficas. Uma dessas substâncias foi identificada por meio de cromatografia em camada delgada como sendo o ácido úsnico. A segunda substância, que se encontra presente em maior concentração em relação aos demais constituintes nos extratos, trata-se do ácido homossequicáico. As análises em cromatografia em camada delgada (CCD e cromatografia líquida de alta eficiência (CLAE revelaram ainda a presença do ácido salazínico. Os dados obtidos tornam possível atribuir a atividade antibiótica observada nesta espécie a uma provável associação sinérgica destas substâncias.The antimicrobian activity of crude extracts from Ramalina sorediosa was detected by the diffusion disc-paper method. Two phenolic compounds from the lichen considered active were detected by using biochromathograhyc technique. Two of those compounds were identified through thin layer chromatographic technique (TLC as been usnic acid and the second one, wich is present in higher concentration when compared with the other substances, was the homosekikaik acid. The TLC and high-pressure liquid chromatography (HPLC assays still detected the salazanic acid presence. The obtained data make it possible to attribute the antibiotic activity of this species to a synergic association of those two substances.

  10. Ritmos electrónicos y raves en la mitad del mundo. Etnografía del fenómeno tecno en Ecuador

    Directory of Open Access Journals (Sweden)

    Voirol , Jérémie

    2006-05-01

    Full Text Available El fenómeno tecno ecuatoriano se inicia en Montañita hacia 1992-1993 y se desarrolla principalmente en Quito y Guayaquil. El surgimiento y desarrollo de este fenómeno están marc a d o s por la influencia del movimiento tecno euro p e o - n o rteamericano y es dinamizado por extranjeros que llevan la música al país. Los jóvenes que escuchan tecno y participan en las fiestas provienen de clases altas, y lo utilizan como elemento distintivo y diferenciador con respecto a lo popular, lo cual rechazan. La fiesta tecno es un ritual de fin de semana que marca una ruptura con lo cotidiano (evacuar tensiones, sentimiento de bienestar, etc. y que arraiga a los participantes a lo local, pero a la vez gira en torno a los consumos de cultura europeo-norteamericana.

  11. The difference between the crystallization processes induced by mechanical milling and annealing under normal and high pressure in amorphous Fe-N alloy

    CERN Document Server

    LiuLi; Guo Xing Yuan; Zhao Xu Dong; Yao Bin; Su Wen Hui

    2002-01-01

    An amorphous Fe-N alloy was prepared by ball milling a mixture of Fe and h-BN. Its crystallization processes induced by mechanical milling (MM) and annealing under normal and high pressure were studied. The crystallization product of the amorphous Fe-N alloy induced by MM and annealing at temperatures between 690 and 800 K under pressures of 3-4 GPa is epsilon-Fe sub x N, while the thermal crystallization product under normal pressure is gamma'-Fe sub 4 N. The difference between the crystallization products produced by mechanical and thermal crystallization is attributed to the effects of local pressure and local temperature produced by ball collisions.

  12. La Interacción Mutua entre Fuentes y las Aparentes Anomalías en el Fenómeno de Interferencia

    Directory of Open Access Journals (Sweden)

    Reinaldo Welti

    2002-01-01

    Full Text Available En la mayoría de los textos de física del nivel básico universitario al tratar el fenómeno de interferencia suponen que las fuentes irradian de la misma forma cualquiera sea la distancia entre ellas. En algunas situaciones esta suposición puede llevar a aparentes anomalías en la conservación de la energía. En este trabajo se muestra que estas anomalías se resuelven solamente si el fenómeno de interferencia se presenta en un contexto que tenga en cuenta las interacciones entre las fuentes y el generador que suministra energía a las mismas.

  13. estudo exploratório sobre o fenómeno no Estabelecimento Prisional de Paços de Ferreira

    OpenAIRE

    Ferreira, Ana Cristina Oliveira

    2011-01-01

    O presente estudo aborda o fenómeno das saídas precárias (SP) enquanto licenças de saída do estabelecimento prisional (EP) que, à semelhança das visitas, correspondência, contactos telefónicos e outros meios de comunicação, constituem uma das formas que os reclusos têm de contactar com o exterior (Lei n.º 115/2009, de 12 de Outubro). Dada a escassez de estudo nesta área, considerou-se importante dar um contributo para a compreensão deste fenómeno, tendo-se estabelecido como principais obje...

  14. Effective field theory and Ab-initio calculation of p-type (Ga, Fe)N within LDA and SIC approximation

    Science.gov (United States)

    Salmani, E.; Mounkachi, O.; Ez-Zahraouy, H.; El Kenz, A.; Hamedoun, M.; Benyoussef, A.

    2013-03-01

    Based on first-principles spin-density functional calculations, using the Korringa-Kohn-Rostoker method combined with the coherent potential approximation, we investigated the half-metallic ferromagnetic behavior of (Ga, Fe)N co-doped with carbon within the self-interaction-corrected local density approximation. Mechanism of hybridization and interaction between magnetic ions in p-type (Ga, Fe)N is investigated. Stability energy of ferromagnetic and disorder local moment states was calculated for different carbon concentration. The local density and the self-interaction-corrected approximations have been used to explain the strong ferromagnetic interaction observed and the mechanism that stabilizes this state. The transition temperature to the ferromagnetic state has been calculated within the effective field theory, with a Honmura-Kaneyoshi differential operator technique.

  15. Variación en el contenido de L-dopa y compuestos fenólicos durante el desarrollo de semilla de Vicia faba L.

    OpenAIRE

    García Sánchez, Isabel

    2012-01-01

    Estudios recientes han demostrado que el haba además de su alto contenido de proteína, posee otras sustancias benéficas para la salud, como son los compuestos fenólicos que actúan como antioxidantes y la L-dopa, aminoácido que retrasa los síntomas severos del síndrome de Parkinson. Por lo que el presente trabajo tuvo como objetivo caracterizar la variación de componentes químicos como proteína soluble, compuestos fenólicos, L-dopa y L-tirosina de colectas de Vicia faba L. provenientes de la...

  16. Spring fen Scheuchzerio-Caricetea nigrae in the Polish Western Carpathians – vegetation diversity in relation to soil and feeding waters

    Directory of Open Access Journals (Sweden)

    Anna Koczur

    2013-05-01

    Full Text Available The species composition of vegetation associated with the Carpathian fens primarily depends on the type of water present and the hydrological feeding of the soils that occur there. These, in turn, shape the fertility of the fens. Those with typically formed Carici-Agrostietum caninae and Valeriano-Caricetum flavae fundamentally differ in the properties of their soils and feeding waters. These include differences in mineral content, pH, CaCO3 levels, degree of peat decomposition, electrical conductivity and oxygenation of the waters that feed the fens. Carici-Agrostietum caninae is a homogenous plant association adapted to extreme habitat conditions. It is characterized by a very narrow range of essential soil and feeding water parameters. Valeriano-Caricetum flavae is a highly diverse association. Considerable diversity both in terms of plant species and vegetation structure reflects very wide ranges in the properties of soil and feeding water. Vegetation patches of transitory character were also identified. These contained plant species characteristic of both associations. The character of the vegetation depends mainly on fen soil pH and the degree of mineralization of the feeding waters. It is only these parameters that allow intermediate patches to be clearly distinguished. The degree of peat decomposition, mineral content and water oxygenation all differ for Carici-Agrostietum caninae and Valeriano-Caricetum flavae, whereas the values for intermediate patches display a range of parameters typical of both investigated associations. Consequently, vegetation present in these patches reflects to a greater or lesser extent one of the two analyzed plant associations.

  17. Un modelo matemático para fenómenos de intercambio y difusión en pañales superabsorbentes

    OpenAIRE

    Estrada, Hernán; Mantilla, Ignacio; Roncancio, Weimar

    2013-01-01

    Se presenta un modelo matemático que permite estudiar dosde los fenómenos físicos que ocurren internamente en un pañal, como lo son el transporte de líquido en la celulosa y el intercambio de éste entre la celulosa y los gránulos. El desarrollo conduce a un sistema de ecuaciones diferenciales parciales, complementado con condiciones iniciales y de frontera.

  18. Slow-release carbohydrates: growing evidence on metabolic responses and public health interest. Summary of the symposium held at the 12th European Nutrition Conference (FENS 2015)

    OpenAIRE

    Vinoy, Sophie; Laville, Martine; Feskens, Edith

    2016-01-01

    To draw attention to the necessity of considering differences in the digestibility of carbohydrates, and more specifically of starch, a symposium was held at the 12th European Nutrition Conference (FENS), which took place in Berlin from October 20 to 23, 2015. The purpose of this session was to present the consolidated knowledge and recent advances regarding the relationship between slow-release carbohydrates, metabolic responses, and public health issues. Three main topics were presented: 1)...

  19. Conteúdo de fenólicos, flavonoides totais e atividade antioxidante de amostras de própolis comerciais

    Directory of Open Access Journals (Sweden)

    Elizângela Alves

    2013-01-01

    Full Text Available Neste trabalho foram determinadas algumas características físico-químicas de própolis de Santa Maria- RS. Foram analisadas seis amostras comerciais obtidas em farmácias e lojas de produtos naturais na cidade citada. A composição química, quanto aos fenólicos e flavonoides totais, assim como a atividade antioxidante, foi testada e comparada. A alta atividade antioxidante dos extratos puros (ou diluídos foi explicada pelo teor dos flavonoides e fenólicos totais, confirmando a relação desses compostos na ação preventiva contra radicais livres. As seis amostras comerciais analisadas possuíram de fenólicos 70,60 mg a 539,10 mg (expresso em mg de ácido gálico/g de extrato de própolis e de flavonoides 48,95 mg a 114,50 mg (expresso em mg de quercetina/g de extrato de própolis. A atividade antioxidante maior foi do extrato aquoso, tanto pela inibição do radical DPPH quanto pela atividade quelante. No extrato aquoso de própolis obteve-se resultados satisfatórios para uma futura aplicação em alimento.

  20. Ķīnas fen šui ģeomantikas iezīmes Heian perioda japāņu dārzos

    OpenAIRE

    Gribuste, Ieva

    2016-01-01

    Darbs - “Ķīnas Fen Šui Ģeomantikas Iezīmes Heian Perioda Japāņu Dārzos” apkopo fen šui pamatidejas un apskata kā tās ir ietekmējušas un izpaužas Heian perioda dārzniecībā un ainavu arhitektūrā Japānā. Mūsdienās, ātrās informācijas apmaiņas laikmetā, aizvien lielāku popularitāti Eiropā iegūst Āzijā radusies filozofija par personīgās harmonijas sasniegšanu ar apkārtējās vides sakārtošanas palīdzību, proti, fen šui prakse. Tā ir ieguvusi īpaši lielu atsauksmi mājas interjera plānošanas ziņā, ta...

  1. El Frente Estudiantil Nacional (FEN: juventud y estudiantado en el proceso contestatario de los años sesenta en Argentina

    Directory of Open Access Journals (Sweden)

    Alejandra Reta

    2009-12-01

    Full Text Available Este artículo forma parte de un proyecto más amplio que aborda el proceso de acercamiento al Peronismo por parte de un sector del movimiento estudiantil en Argentina durante los años sesentas, tomando el caso particular del Frente Estudiantil Nacional (FEN. El FEN fue una organización universitaria “de pasaje al peronismo”, que buscaba inserción “legítima” en el mismo, vinculándose a sectores del peronismo histórico y al trabajo barrial.Proponemos privilegiar el análisis de documentos, aunque incluimos también algunos testimonios que nos sirven de apoyo. A partir de allí pretendemos explorar algunos “componentes contestatarios”, ligados al clima de ideas de la época, y visualizar cómo este actor colectivo se posiciona dentro de las categorías de “juventud” y del “estudiantado”, que aparecen en el discurso, considerando que el FEN reivindicó constantemente su carácter de tendencia estudiantil universitaria y su militancia juvenil.

  2. Effective field theory and Ab-initio calculation of p-type (Ga, Fe)N within LDA and SIC approximation

    Energy Technology Data Exchange (ETDEWEB)

    Salmani, E. [LMPHE, associe au CNRST (URAC 12), Faculte des Sciences, Universite Mohammed V-Agdal, Rabat (Morocco); Mounkachi, O. [Institute of Nanomaterials and Nanotechnology, MAScIR, Rabat (Morocco); Ez-Zahraouy, H., E-mail: ezahamid@fsr.ac.ma [LMPHE, associe au CNRST (URAC 12), Faculte des Sciences, Universite Mohammed V-Agdal, Rabat (Morocco); El Kenz, A. [LMPHE, associe au CNRST (URAC 12), Faculte des Sciences, Universite Mohammed V-Agdal, Rabat (Morocco); Hamedoun, M. [Institute of Nanomaterials and Nanotechnology, MAScIR, Rabat (Morocco); Benyoussef, A. [LMPHE, associe au CNRST (URAC 12), Faculte des Sciences, Universite Mohammed V-Agdal, Rabat (Morocco); Institute of Nanomaterials and Nanotechnology, MAScIR, Rabat (Morocco); Hassan II Academy of Science and Technology, Rabat (Morocco)

    2013-03-15

    Based on first-principles spin-density functional calculations, using the Korringa-Kohn-Rostoker method combined with the coherent potential approximation, we investigated the half-metallic ferromagnetic behavior of (Ga, Fe)N co-doped with carbon within the self-interaction-corrected local density approximation. Mechanism of hybridization and interaction between magnetic ions in p-type (Ga, Fe)N is investigated. Stability energy of ferromagnetic and disorder local moment states was calculated for different carbon concentration. The local density and the self-interaction-corrected approximations have been used to explain the strong ferromagnetic interaction observed and the mechanism that stabilizes this state. The transition temperature to the ferromagnetic state has been calculated within the effective field theory, with a Honmura-Kaneyoshi differential operator technique. - Highlights: Black-Right-Pointing-Pointer The paper focus on the study the magnetic properties and electronic structure of p-type (Ga, Fe)N within LDA and SIC approximation. Black-Right-Pointing-Pointer These methods allow us to explain the strong ferromagnetic interaction observed and the mechanism for its stability and the mechanism of hybridization and interaction between magnetic ions in p-type (Ga, Fe). Black-Right-Pointing-Pointer The results obtained are interesting and can be serve as a reference in the field of dilute magnetic semi conductor.

  3. Turn on, fade out - methane exchange in a coastal fen over a period of six years after rewetting

    Science.gov (United States)

    Jurasinski, Gerald; Glatzel, Stephan; Hahn, Juliane; Koch, Stefan; Koch, Marian; Koebsch, Franziska

    2016-04-01

    The rewetting of drained peatlands is widely regarded as an adequate measure for the mitigation of greenhouse gas emissions. Therefore, especially in NE Germany, many peatlands are being rewetted. Our knowledge about greenhouse gas exchange associated with rewetting is mainly based on short-term experiments or space-for-time substitutions. These approaches do not consider the transient character of ecosystem acclimatization to flooding by rewetting. Moreover data in this regard on coastal peatland ecosystems are sparse. Here, we present 7 years of data on CH4-exchange in a coastal fen after rewetting by flooding. On the site „Rodewiese", which is located within the NSG "Hütelmoor und Heiligensee" in the Northeast of Rostock, NE Germany, we have established a long term research observatory addressing atmospheric C-exchange. The site is part of the TERENO network. Since summer 2009 we determine CH4 fluxes with closed chambers distributed widely across the study site and CO2-exchange with eddy covariance as well as ancillary data on vegetation, hydrology, and biogeochemistry. This talk addresses the CH4-exchange over time whereas CO2-exchange data are presented by Koebsch et al. in the same session. Rewetting turned the site from a summer dry fen with mean annual water levels of around -0.08m into a shallow lake with water levels up to 0.60m. In the first year after flooding, we observed a substantial die-back of vegetation, especially in stands of Carex acutiformis. Flooding increased methane release rates to extremely high levels of up to 4.3 t ha‑1 a‑1 for sedge stands and 2.7 t ha‑1 a‑1 on average, which amounts to 75.6 t ha‑1 a‑1 in CO2-equivalents. Thereafter, the averaged annual CH4 emissions decreased asymptotically and where at an average of 0.5 t ha‑1 a‑1 (14 t ha‑1 a‑1 in CO2-equivalents) in 2015. Factoring in the NEE of the growing season (from Eddy measurements) suggests that the system may be slightly above neutral with respect to

  4. CO{sub 2} exchange of a sedge fen in southern Finland - the impact of a drought period

    Energy Technology Data Exchange (ETDEWEB)

    Aurela, Mika; Laurila, Tuomas; Tuovinen, Juha-Pekka [Finnish Meteorological Inst., Helsinki(Finland)]. e-mail: mika.aurela@fmi.fi; Riutta, Terhi; Tuittila, Eeva- Stiina [Dept. of Forest Ecology, Univ. of Helsinki, Helsinki (Finland); Vesala, Timo; Rinne, Janne; Haapanala, Sami [Dept. of Physical Sciences, Univ. of Helsinki, Helsinki( FI); Laine, Jukka [Finnish Forest Research Inst., Parkano Research Unit, Parkan o (Finland)

    2007-11-15

    Eddy covariance (EC) measurements of net ecosystem CO{sub 2} exchange (NEE) were conducted on a boreal sedge fen in southern Finland (61 deg 50 N, 24 deg 12 E) during a 1.5-yr period covering two summers in 2004-2005. The EC data were complemented by chamber measurements, which enabled the partition of the daytime NEE into respiration and photosynthesis. A special emphasis was put on the hydrometeorological responses of CO{sub 2} exchange during a drought period in July 2005. A mean CO{sub 2} efflux of 0.009 mgCO{sub 2} /m{sup 2}/s was observed during mid-winter (January-February), while the night-time respiration during the two Julys averaged 0.09 mgCO{sub 2} /m{sup 2}/s. During both years the mean mid-day uptake in late July was about -0.16 mgCO{sub 2} /m{sup 2}/s. An annual CO{sub 2} balance of -188 gCO{sub 2}/m{sup 2} was observed in 2005. A slightly higher net sink of -219 gCO{sub 2}/m{sup 2} was estimated for 2004. The drought period experienced in July 2005 caused a clear depression in the daily NEE values. From the combined analysis of EC and chamber measurements it was concluded that this was mainly due to increased respiration, but evidence was also found of suppressed photosynthesis due to a high VPD.

  5. The hydrogeologic connectivity of a low-flow saline-spring fen peatland within the Athabasca oil sands region, Canada

    Science.gov (United States)

    Wells, Corey M.; Price, Jonathan S.

    2015-12-01

    Saline springs can provide clues as to the nature of groundwater flow, including how it relates to subsurface wastewater storage and the distribution of solutes in the landscape. A saline-spring peatland neighboring a proposed in-situ oil facility was examined near Fort McMurray, Alberta (Canada). The study area is situated just north of a saline groundwater discharge zone, which coincides with the erosional edge of the Cretaceous Grand Rapids Formation. Na+ (mean 6,949 mg L-1) and Cl- (mean 13,776 mg L-1) were the dominant salts within the peatland, which increased by an order of magnitude in the opposite direction to that of the local groundwater flow. Rivers and freshwater wetlands within the study area had anomalously high salinities, in some cases exceeding 10,000 mg L-1 total dissolved solids within deeper sediments. Saline-spring features were observed as far as 5 km from the study area. A low-permeability mineral layer underlying the peatland restricted vertical groundwater exchange (estimated to be less than several mm over the 4-month study period). Sand and gravel lenses underlying the fen's high-salinity zone may function as areas of enhanced discharge. High Cl/Br ratios point to halite as a potential source of salinity, while δ18O and δ2H signatures in groundwater were lower than modern-day precipitation or Quaternary aquifers. The complex connectivity of saline-spring wetlands within the landscape has implications for industry and land-use managers, and justifies incorporating them into monitoring networks to better gauge the magnitude and flow history of natural saline discharge in the oil sands region.

  6. Estudio sobre la peligrosidad del fenómeno de vientos fuertes en España

    Directory of Open Access Journals (Sweden)

    Piserra, María Teresa

    1994-04-01

    Full Text Available Generally speaking, the studies on the wind in Spain are carried out from the point of view of the feasibility of the exploitation of its energy. In order to achieve this aim it is necessary to observe and quantify the speed, direction and frequency of the winds predominant in each area, since these are the winds which, due to their constancy, allow the exploitation of their energy. Nevertheless, the following study takes a different approach. It tries to analyze the destruction capacity of the wind by means of a statistical treatment of a series of maximum gusts registered in the different climatological stations. The final result is the map of wind hazard by provinces, which represents an initial approximation to the knowledge of wind phenomenon intensity studied through its strongest manifestation.

    En general, los estudios sobre el viento en España se analizan desde la óptica de la viabilidad de su aprovechamiento energético. Para ello, es preciso observar y cuantificar la velocidad, dirección y frecuencia de los vientos predominantes en cada zona, ya que éstos son los que, por su constancia, hacen posible su explotación energética. Sin embargo, el estudio desarrollado a continuación se enfoca en un sentido diferente, ya que pretende analizarla capacidad destructiva del viento, mediante el tratamiento estadístico de las series de rachas máximas registradas en las diferentes estaciones climatológicas. El resultado final es un mapa de peligrosidad de viento por provincias, que constituye una primera aproximación al conocimiento de la intensidad del fenómeno del viento, desde la perspectiva de sus manifestaciones más extremas.

  7. Hydrological Controls on Ecosystem CO2 and CH4 Exchange in a MIXED Tundra and a FEN within an Arctic Landscape UNDER Current and Future Climates

    Science.gov (United States)

    Grant, R. F.; Humphreys, E.; Lafleur, P.

    2014-12-01

    Variation in CO2 and CH4 exchange in years with contrasting weather is strongly affected by hydrology in landscapes underlain by permafrost. Hypotheses for this variation were incorporated into the ecosystem model ecosys which simulated CO2 and CH4 fluxes along a topographic gradient within an arctic landscape at Daring Lake, NWT, Canada. Fluxes modelled at mixed tundra and fen sites within the gradient were compared with CO2 fluxes measured at eddy covariance towers from 2006 to 2009, and with CH4 fluxes measured with surface chambers in 2008. Slopes and correlation coefficients from regressions of modelled vs. measured CO2 fluxes were 1.0 ± 0.1 and 0.7 - 0.8 for both sites in all years. At the mixed tundra site, rises in net CO2 uptake in warmer years with earlier snowmelt were constrained by midafternoon declines in CO2 influxes when vapor pressure deficits (D) exceeded 1.5 kPa, and by rises in CO2 effluxes with greater active layer depth (ALD). Consequently annual net CO2 uptake at this site rose little with warming. At the fen site, CO2 influxes declined less with D and CO2 effluxes rose less with warming, so that rises in net CO2 uptake in warmer years were greater than those at the mixed tundra site. The greater declines in CO2 influxes with warming at the mixed tundra site were modelled from greater soil-plant-atmosphere water potential gradients that developed in drier soil, and the smaller rises in CO2 effluxes with warming at the fen site were modelled from O2 constraints to heterotrophic and below-ground autotrophic respiration that limited their responses to greater ALD. Modelled and measured CH4 exchange during July and August indicated very small influxes at the mixed tundra site, and larger emissions at the fen site. Emissions of CH4 modelled during soil freezing in October - November contributed about one-third of the annual total, and so should be included in estimates of annual emissions. These contrasting responses to warming under current

  8. Pyometra u fen

    OpenAIRE

    Klimešová, Vanda

    2012-01-01

    This bachelor thesis deals with female dogs' disorders of pyometra and its problems. The aim of this thesis is to provide comprehensive information on this serious disorder of the reproductive system. A part of the thesis is also a questionnaire survey that is concerned with the disease itself and also with the owners' knowledge of the female dog diseases. Pyometra is an inflammatory disease of the uterus. In most cases, the disease is caused by the persistent production of progesteron...

  9. Análisis de fenómenos de localización en materiales cohesivo-friccionales

    Directory of Open Access Journals (Sweden)

    Martínez Cutillas, Francisco J.

    1994-08-01

    Full Text Available The growth of the finite element method as a tool in structural analysis requires the use of concrete models capable of exhibiting responses beyond the elastic range. In recent years, considerable interest has arisen in the characterization and modeling of materials which include a softening phase in their mechanical behaviour. This softening is often related to the interaction between microstructural components of the material, which results in the generation of non-homogeneous strain states where deformations are localized in relatively thin bands. The object of this work is to contribute to the numerical analysis of the phenomenon of strain localization as it arises in cohesive frictional materials. Special attention is paid to the behaviour of mass concrete and, particularly, to its characterization and modeling during uniaxial compression.

    El creciente empleo del método de los elementos finitos como herramienta de cálculo estructural requiere la definición de modelos de hormigón capaces de reproducir respuestas más allá del rango eminentemente elástico. En los últimos años ha crecido fuertemente el interés en la caracterización y modelización de materiales cuyo comportamiento mecánico incluye una fase de reblandecimiento en las etapas próximas a la rotura. En muchos casos dicho reblandecimiento está asociado a la interacción entre los componentes microestructurales del material que genera estados de deformación no homogéneos con una localización de las deformaciones en bandas de pequeño espesor. El objeto del presente trabajo es contribuir al análisis por métodos numéricos del fenómeno de localización de deformaciones en materiales cohesivo fricciónales. Se dedica especial atención al hormigón en masa y, de manera particular, a la caracterización y modelización de su comportamiento en compresión uniaxial.

  10. Organic sediment formed during inundation of a degraded fen grassland emits large fluxes of CH4 and CO2

    Directory of Open Access Journals (Sweden)

    A. Freibauer

    2010-12-01

    Full Text Available Peatland restoration by inundation of drained areas can alter local greenhouse gas emissions by altering rates of CO2 and CH4 emissions. Factors that can influence these emissions include the quality and amount of substrates available for anaerobic degradation processes and the sources and availability of electron acceptors. In order to learn about possible sources of high CO2 and CH4 emissions from a rewetted degraded fen grassland, we performed incubation experiments that tested the effects of fresh plant litter in the flooded peats on pore water chemistry and CO2 and CH4 production and emission. The position in the soil profile of the pre-existing drained peat substrate affected initial rates of anaerobic CO2 production subsequent to flooding, with the uppermost peat layer producing the greatest specific rates of CO2 evolution. CH4 production rates depended on the availability of electron acceptors and was significant only when sulfate concentrations were reduced in the pore waters. Very high specific rates of both CO2 (maximum of 412 mg C d−1 kg−1 C and CH4 production (788 mg C d−1 kg−1 C were observed in a new sediment layer that accumulated over 2.5 years since the site was flooded. This new sediment layer was characterized by overall low C content, but represented a mixture of sand and relatively easily decomposable plant litter from reed canary grass killed by flooding. Samples that excluded this new sediment layer but included intact roots remaining from flooded grasses had specific rates of CO2 (max. 28 mg C d−1 kg−1 C and CH4 (max. 34 mg C d−1 kg−1 C production that were 10–20 times lower, and were comparable to those of newly flooded upper peat layer. Lowest rates of anaerobic CO2 and CH4 production (range of 4–8 mg C d−1 kg−1 C and −1 kg−1 C were observed when all fresh organic matter sources (plant litter and roots were excluded. In conclusion, the presence of fresh organic substrates such as plant and

  11. High net CO2 and CH4 release at a eutrophic shallow lake on a formerly drained fen

    Science.gov (United States)

    Franz, Daniela; Koebsch, Franziska; Larmanou, Eric; Augustin, Jürgen; Sachs, Torsten

    2016-05-01

    Drained peatlands often act as carbon dioxide (CO2) hotspots. Raising the groundwater table is expected to reduce their CO2 contribution to the atmosphere and revitalise their function as carbon (C) sink in the long term. Without strict water management rewetting often results in partial flooding and the formation of spatially heterogeneous, nutrient-rich shallow lakes. Uncertainties remain as to when the intended effect of rewetting is achieved, as this specific ecosystem type has hardly been investigated in terms of greenhouse gas (GHG) exchange. In most cases of rewetting, methane (CH4) emissions increase under anoxic conditions due to a higher water table and in terms of global warming potential (GWP) outperform the shift towards CO2 uptake, at least in the short term.Based on eddy covariance measurements we studied the ecosystem-atmosphere exchange of CH4 and CO2 at a shallow lake situated on a former fen grassland in northeastern Germany. The lake evolved shortly after flooding, 9 years previous to our investigation period. The ecosystem consists of two main surface types: open water (inhabited by submerged and floating vegetation) and emergent vegetation (particularly including the eulittoral zone of the lake, dominated by Typha latifolia). To determine the individual contribution of the two main surface types to the net CO2 and CH4 exchange of the whole lake ecosystem, we combined footprint analysis with CH4 modelling and net ecosystem exchange partitioning.The CH4 and CO2 dynamics were strikingly different between open water and emergent vegetation. Net CH4 emissions from the open water area were around 4-fold higher than from emergent vegetation stands, accounting for 53 and 13 g CH4 m-2 a-1 respectively. In addition, both surface types were net CO2 sources with 158 and 750 g CO2 m-2 a-1 respectively. Unusual meteorological conditions in terms of a warm and dry summer and a mild winter might have facilitated high respiration rates. In sum, even after 9

  12. Biodegradación de los compuestos fenólicos presentes en el alpechín

    Directory of Open Access Journals (Sweden)

    Maestro Durán, R.

    1991-08-01

    Full Text Available Oil-mill wastewater is the main responsible of the pollution in Andalusian due to high content of organic substances. Its depuration by methanization is difficult because of the antimicrobial activity of phenolic derivatives. These compounds can be drastically reduced by a previous aerobic treatment of the oil mill wastewater with specific microorganisms. After this pretreatment, anaerobic depuration takes place without inhibition, the velocity of the reaction being 5 times higher than before the pretreatment. In this paper a qualitative study of the phenols present in oil-mill wastewater by thin layer chromatography has been done. Beside that, quantitative determination of total phenols, ortoand meta-diphenols as well as Chemical Oxigen Demand (COD before the treatment, after the pretreatment and after biomethanization have been carried out. Finally, leucoanthocyanins that could originate polymerized phenols have not been found.

    Las aguas residuales de la obtención del aceite de oliva o alpechines son responsables de la mayor contaminación medioambiental de Andalucía por su elevada carga de materia orgánica. Su depuración por biometanización es difícil debido a la actividad antimicrobiana de los compuestos fenólicos. Este tipo de sustancias puede eliminarse en gran parte tratando previamente el alpechín por vía aerobia con microorganismos específicos, después de lo cual la depuración anaerobia tiene lugar sin inhibiciones, siendo la constante de velocidad cinco veces superior a la de antes del pretratamiento. En este trabajo se hace un estudio cualitativo de los fenoles por cromatografía en capa fina y cuantitativo de los fenoles totales, orto- y meta-difenoles, así como de la Demanda Química de Oxígeno del alpechín antes del tratamiento, después del pretratamiento y después de la biometanización. Se ha comprobado también la ausencia de leucoantocianinas que pudieran dar origen a fenoles polimerizados.

  13. Evaluación del efecto antioxidante y quimioprotector de extractos fenólicos de semillas de manzana

    Directory of Open Access Journals (Sweden)

    Rocha-Guzmán, N. E.

    2007-03-01

    Full Text Available Phenolic extracts from apple seeds (Malus domestica belonging to the Red delicious (Rd and Blanca de asturias (Ba varieties were studied. Two extraction sequences with organic solvents were performed to evaluate hydrophilic phytochemicals: one with hexane, ethyl acetate and 50% methanol and the other with hexane and 70% acetone. For both apple varieties, acetone extracts showed higher total phenolics and condensed tannin content than ethyl acetate or aqueous methanol extracts. The same trend was observed with acetone extracts, which showed the highest free radical scavenging activity (%RSA. Bidimensional thin later chromatography plates gave positive evidence for proanthocyanidins (condensed tannins. The effect of crude  extracts on transformed cells (HeLa was evaluated and found to be as strong as the positive control (catechin. Aqueous acetone extracts showed the highest inhibition to cell proliferation of all tested extracts and controls.Se estudiaron extractos fenólicos de semillas de manzana (Malus domestica de variedades Red delicious (Rd y Blanca de asturias (Ba. Se realizaron dos procedimientos de extracción sucesiva con solventes orgánicos para la evaluación de fitoquímicos con naturaleza hidrofílica, uno con hexano, acetato de etilo, metanol 50% y otro con hexano y acetona 70%. Los extractos acetónicos mostraron un mayor contenido de fenoles totales y de taninos condensados en comparación con los extractos de acetato de etilo y metanol acuoso en las dos variedades estudiadas. Independientemente de la variedad, los extractos acetónicos mostraron mayor capacidad atrapadora de radicales libre (%ARL, en comparación con los demás extractos. El análisis cromatográfico de los extractos mediante capa fina bidimensional fue positivo para proantocianidinas (taninos condensados. También se evaluó el efecto biológico de los extractos crudos sobre la proliferación de células transformadas (células HeLa, mismo que fue equivalente

  14. Ecosystem CO2 and CH4 exchange in a mixed tundra and a fen within a hydrologically diverse Arctic landscape: 1. Modeling versus measurements

    Science.gov (United States)

    Grant, R. F.; Humphreys, E. R.; Lafleur, P. M.

    2015-07-01

    CO2 and CH4 exchange are strongly affected by hydrology in landscapes underlain by permafrost. Hypotheses for these effects in the model ecosys were tested by comparing modeled CO2 and CH4 exchange with CO2 fluxes measured by eddy covariance from 2006 to 2009, and with CH4 fluxes measured with surface chambers in 2008, along a topographic gradient at Daring Lake, NWT. In an upland tundra, rises in net CO2 uptake in warmer years were constrained by declines in CO2 influxes when vapor pressure deficits (D) exceeded 1.5 kPa and by rises in CO2 effluxes with greater active layer depth. Consequently, net CO2 uptake rose little with warming. In a lowland fen, CO2 influxes declined less with D and CO2 effluxes rose less with warming, so that rises in net CO2 uptake were greater than those in the tundra. Greater declines in CO2 influxes with warming in the tundra were modeled from greater soil-plant-atmosphere water potential gradients that developed under higher D in drained upland soil, and smaller rises in CO2 effluxes with warming in the fen were modeled from O2 constraints to heterotrophic and belowground autotrophic respiration from a shallow water table in poorly drained lowland soil. CH4 exchange modeled during July and August indicated very small influxes in the tundra and larger effluxes characterized by afternoon emission events caused by degassing of warming soil in the fen. Emissions of CH4 modeled from degassing during soil freezing in October-November contributed about one third of the annual total.

  15. Atividade antimicrobiana, antioxidante e teor de compostos fenólicos em casca e amêndoa de frutos de manga

    Directory of Open Access Journals (Sweden)

    Kettelin Aparecida Arbos

    2013-04-01

    Full Text Available O processamento industrial de frutos de manga gera elevada quantidade de resíduos agroindustriais, representados pelas cascas e sementes (amêndoa, os quais, sem aplicação viável, acabam sendo descartados diretamente no meio ambiente. Esses resíduos são ricos em compostos bioativos, amplamente reconhecidos pelas suas propriedades promotoras da saúde e em aplicações tecnológicas. Os objetivos foram avaliar as atividades antimicrobiana e antioxidante e o teor de compostos fenólicos de dois extratos: um obtido da casca (FC e outro da amêndoa (FA de manga variedade 'Tommy Atkins'. O teor de compostos fenólicos totais variou de 3.123 a 6.644 mg de catequina/100 g. Os extratos FC e FA demonstraram relevante atividade antimicrobiana frente às cepas das bactérias Escherichia coli, Salmonella sp., Pseudomonas aeruginosa . Staphylococcus aureus, determinadas pelo método de difusão em disco. A ação antioxidante de FC e FA aumentou com o aumento das concentrações testadas, atingindo o valor máximo de 88% (FC. Em todas as concentrações testadas os extratos FC apresentaram ação antioxidante significativamente superior às respectivas concentrações dos extratos FA. Esses resultados sugerem potencial aplicação dos resíduos de manga como fonte de compostos fenólicos, substâncias antimicrobianas e antioxidantes, podendo ser explorados pelas indústrias de alimentos.

  16. Bíodegradación de los compuestos fenólícos presentes en el alpechín

    OpenAIRE

    Maestro Durán, R.; Borja Padilla, R.; Martín, Antonio; Fiestas Ros de Ursinos, J. A.; Alba Mendoza, J.

    1991-01-01

    Las aguas residuales de la obtención del aceite de oliva o alpechines son responsables de la mayor contaminación medioambiental de Andalucía por su elevada carga de materia orgánica. Su depuración por biometanización es difícil debido a la actividad antimicrobiana de los compuestos fenólícos. Este tipo de sustancias puede eliminarse en gran parte tratando previamente el alpechín por vía aerobia con microorganismos específicos, después de lo cual la depuración anaerobia ti...

  17. Relación entre compuestos fenólicos y calidad nutritiva en especies pratenses.

    OpenAIRE

    Vázquez de Aldana, Beatriz R.; García Ciudad, A.; García Criado, B.

    2009-01-01

    [ESP]Los compuestos fenólicos comprenden un grupo de compuestos que a menudo influyen de forma negativa en la calidad del pasto. El objetivo de este trabajo fue determinar el contenido de fenoles totales en varias especies frecuentes en pastos de dehesa de la provincia Salamanca y establecer su relación con otros parámetros de la calidad nutritiva (fibra ácido detergente, fibra neutro detergente, celulosa, lignina, proteína y digestibilidad). Se encontraron correlaciones negativas signific...

  18. El fenómeno delictivo juvenil de la mara: Un estudio regional en Chiapas/The mara youth criminal phenomenon: A regional study in Chiapas

    OpenAIRE

    Jorge Humberto Martínez Trejo; Verónica C. Castellanos León

    2013-01-01

    El objetivo de la presente investigación es comprender el fenómeno de la tropicalización de la organización delictiva juvenil de La Mara en la región de Chiapas. El desarrollo de la misma, es eminentemente de corte etnometodológico, y se encuentra actualmente en proceso de desarrollo. Sin embargo, se recogen evidencias parciales del perfil criminológico de los miembros de La Mara de Centroamérica y la de Chiapas. Dichos estudios se realizaron en el período de junio del 2011 a junio del 2012, ...

  19. El homeschooling en España : descripción y análisis del fenómeno

    OpenAIRE

    Cabo González, Carlos

    2012-01-01

    El contenido del presente trabajo de tesis se estructura en torno a cuatro grandes apartados o capítulos. En el primero de ellos, se fijan los objetivos del trabajo; se establece la metodología; se delimitan los conceptos más frecuentemente utilizados en el estudio (educación, enseñanza, formación e instrucción); se define el fenómeno de la no escolarización; se informa de las diferentes denominaciones de esta práctica educativa; y, finalmente se ofrece un panorama de la situación en la qu...

  20. Fenóis derivados da lignina, carboidratos e aminoaçúcares em serapilheira e solos cultivados com eucalipto em sistemas convencional e fertirrigado

    OpenAIRE

    Rodinei Facco Pegoraro; Ivo Ribeiro Silva; Roberto Ferreira Novais; Nairan Felix Barros; Sebastião Fonseca

    2013-01-01

    Este estudo teve por objetivo avaliar os teores de fenóis derivados de lignina, carboidratos e aminoaçúcares, bem como o estádio de decomposição e a contribuição de compostos de origens vegetal e microbiana para a matéria orgânica do solo (MOS) em sistemas de cultivo convencional e fertirrigado de eucalipto. Foram realizadas coletas de serapilheira e solo (Argissolo) em dois sistemas de cultivo de eucalipto (convencional e fertirrigado) em dois locais de coleta (linha e entrelinha), com três ...

  1. Estudio del fenómeno Social Media en la pequeña empresa del sector TIC español

    OpenAIRE

    Río Onrubia, María Rebeca del

    2014-01-01

    En un mundo en el que cada vez son más las personas que utilizan Internet para llevar a cabo sus comunicaciones y relaciones, tanto a nivel personal como profesional, las Redes Sociales se han convertido en una herramienta, para muchos imprescindible, de interacción social. A lo largo de este proyecto se realizará un análisis exhaustivo de las características del ya conocido como Fenómeno Social Media, para posteriormente centrar toda la atención en las ventajas y desventajas de dicha acti...

  2. Aprendizaje espacial en laberintos en una tarea de discriminación. Los fenómenos de la inhibición latente y del aprendizaje perceptivo.

    OpenAIRE

    Sansa i Aguilar, Joan

    1995-01-01

    [spa] La exposición previa a un estimulo que se usará como estímulo condicionado (EC) en un paradigma de condicionamiento clásico típicamente retrasa el condicionamiento posterior. Este es el fenómeno de la inhibición latente (IL) (Lubow, 1989). Sin embargo, en ocasiones esta exposición tiene el efecto opuesto. Así, en el aprendizaje latente, la exposición a un laberinto de múltiples unidades facilitará la elección del camino correcto cuando posteriormente se introduce e! reforzador (Tolman y...

  3. Analogías de redes eléctricas como herramienta educativa para el estudio de diversos fenómenos físicos

    OpenAIRE

    Gómez Lopera, Salvador Ángel; Cerro Velázquez, Francisco del; Alhama López, Francisco

    2005-01-01

    La resolución de problemas correspondientes a fenómenos físicos regidos por ecuaciones diferenciales en derivadas parciales, lineales o no, implica un conocimiento profundo de cálculo analítico o numérico por lo que, en general, estos problemas no se encuentran al alcance de los alumnos de facultades de ciencias o escuelas de ingeniería, desconocedores en su fase de formación de estas modernas y complejas técnicas matemáticas.A pesar de ello, es posible, en muchos casos, abordar la resolución...

  4. A fragmentação do eu na esquizofrenia e o fenômeno do transitivismo: um caso clínico

    Directory of Open Access Journals (Sweden)

    Luciane Loss Jardim

    2011-01-01

    Full Text Available En este artículo buscamos entender la fragmentación del yo en el cuadro clínico de la esquizofrenia desde una lectura psicoanalítica. Por lo tanto, se presenta una breve digresión histórica del concepto de esquizofrenia por Eugene Bleuler destacando su propuesta sobre la escisión del yo y su visión más complexa de la psicopatología que es consistente con la teoría de la disolución imaginaria de Jacques Lacan acerca del yo en la psicosis. Entonces, se presenta el caso de Julio, un paciente esquizofrénico, que es un caso paradigmático para la comprensión de los síntomas, desde el marco psicoanalítico que presupone la existencia de formaciones inconscientes en la organización de la psicopatología de la esquizofrenia. El caso clínico se analiza en dos segmentos, es decir, el momento de la aparición de la psicosis vinculada con la falta en la estructura simbólica en relación a la función paterna. La falta del padre simbólico desencadena una disolución del yo en la psicosis, entonces, muchos de los fenómenos encontrados en la esquizofrenia es la fragmentación del yo. Julio presenta una identificación imaginaria colmada al otro, una captación por la imagen del otro, sin exclusión recíproca inherente al fenómeno del transitivismo El fenómeno del transitivismo ocurre en el estadio del espejo y aparece en determinados momentos del desarrollo psíquico, que se caracteriza por este momento de báscula, donde las acciones del niño y su semejante son iguales. Por lo tanto, la articulación entre el fenómeno del transitivismo y los síntomas de la esquizofrenia nos permite hacer una lectura de la de la psicosis a partir de este operador.

  5. El Esoterismo y la adivinación como fenómeno comunicativo en la televisión española

    OpenAIRE

    Cid-Leal, Pilar; Recoder, Maria Josep; Cruz Palacios, Emilio

    2015-01-01

    En las parrillas nocturnas de los canales de Televisión Digital Terrestre (TDT) españoles abundan los programas de adivinación con consultas telefónicas. Pese a las transformaciones que ha experimentado el medio televisivo en los últimos años, estos programas, difícilmente clasificables dentro de los géneros televisivos clásicos, se mantienen. Porque son tanto un fenómeno comunicativo como un negocio para las televisiones, los consultorios privados de los vident...

  6. El fenómeno de la victimización en los centros penitenciarios de la Región de Murcia.

    OpenAIRE

    Caravaca Sánchez, Francisco

    2013-01-01

    Hechos delictivos como los robos, amenazas, agresiones físicas y verbales e incluso sexuales se presentan como un hecho cotidiano en la vida penitenciaria, ligado al consumo de sustancias estupefacientes. 2. Hipótesis del estudio El propósito general de esta investigación consiste en conocer y evaluar los diferentes factores sociales y penitenciarios, que se encuentran ligados a la aparición y mantenimiento del fenómeno de la victimización en el ámbito penitenciario. Y posteriormente d...

  7. A adolescência enquanto fenômeno social: possibilidades e necessidades de investigação científica em enfermagem

    Directory of Open Access Journals (Sweden)

    Maria Amélia de Campos Oliveira

    1993-03-01

    Full Text Available Recortando para além dos critérios crono-biológicos, ou seja, compreendendo-a enquanto um fenômeno social, as autoras discutem a redefinição deste objeto para investigação em enfermagem. Com isso, propõem a ampliação do leque de conhecimentos sobre a saúde do adolescente a fim de subsidiar a transformação do perfil de saúde-doença desse grupo populacional.

  8. Una aproximación conceptual y práctica al fenómeno del terrorismo suicida: El caso de Hezbollah

    OpenAIRE

    Alba Cuéllar, Angélica

    2014-01-01

    El terrorismo suicida de carácter islamista es un fenómeno difícilmente comprensible,principalmente en el contexto de las sociedades occidentales y secularizadas, en donde es comúnmente entendido como un acto desprovisto de cualquier forma de racionalidad y enmarcado en el fanatismo religioso. No obstante, se trata de acciones que requieren del marco de organizaciones, de unos objetivos claros y de una racionalidad que considera el costo y el beneficio de su uso. Este artículo presenta un aná...

  9. Utilización de Uvas en la Elaboración de Mermeladas: Estudio de Estabilidad de Compuestos Fenólicos

    OpenAIRE

    Olachea Arce, Angel

    2012-01-01

    Se recoge en la bibliografía consultada diversos trabajos dónde se ha comprobado la presencia de compuestos con actividad beneficiosa para la salud humana en los residuos y subproductos del cultivo de la uva y del proceso de vinificación, concretamente compuestos de tipo fenólicos, carbohidratos y restos proteicos. Los restos de la vinificación representan un volumen importante de residuos/subproductos en el entorno enológico. En concreto, según estadísticas y datos del 2011, en España se ...

  10. Nursing phenomena identified in family planning visits with ICNP - Beta Version 2 Fenómenos de enfermería identificados en consultas de planificación familiar según la ICNP, Versión Beta 2 Fenômenos de enfermagem identificados em consultas de planejamento familiar segundo a ICNP - Versão Beta 2

    Directory of Open Access Journals (Sweden)

    Gislaine Eiko Kuahara Camiá

    2006-10-01

    Full Text Available This descriptive, exploratory, retrospective survey, carried out at a family planning service, aimed to identify nursing phenomena during nursing visits according to the ICNP, Beta version 2. Data were collected based on 52 records of nursing visits, realized from October 2001 to December 2002. To conduct the cross-mapping process, all identified nursing phenomena were joined, organized and compared according to the ICNP's terms. Of the 51 identified nursing phenomena/diagnoses, 46 (90.2% showed exact and partial concordance. The identified nursing phenomena can be used to assist nurses to provide care for clients in family planning services. The ICNP showed to be a comprehensive program, although some terms need to be reviewed and others enhanced. However, considering that it is an international classification applicable to several countries, the mapping process and cross-references were very satisfactory.Esta investigación descriptiva, exploratoria, retrospectiva se llevó a cabo en un servicio de planeo familiar. El objetivo fue identificar los fenómenos de enfermería en consultas según la ICNP, versión Beta 2. La recolección de datos se realizó en 52 historias clínicas, en consultas de enfermería durante el período de octubre del 2001 a diciembre del 2002. Para el mapeo cruzado, todos los fenómenos de enfermería identificados fueron compilados, organizados y comparados con los términos de la ICNP. De los 51 fenómenos/diagnósticos de enfermería identificados, 46 (90,2% presentaron concordancia exacta y parcial. Los fenómenos de enfermería identificados podrán ayudar los enfermeros para el cuidado de clientes que procuran servicios de planificación familiar. La ICNP demostró ser extenso, aunque algunos términos necesitan ser revisados y/o aumentados. Sin embargo, llevando en consideración que se trata de una clasificación internacional aplicable a diversos países, el mapeo y el cruce de sus datos fueron satisfactorios

  11. La cultura física y el deporte: fenómenos sociales /Physical culture and sport: social phenomena

    Directory of Open Access Journals (Sweden)

    Diana A. Camargo R

    2013-08-01

    Full Text Available La cultura física y el deporte son categorías que se han relacionado con la actividad física y la educación física a lo largo del tiempo, retomando diferentes paradigmas de conocimiento; sin embargo, el paradigma imperante ha sido el empírico-analítico, que reduce la mirada a los fenómenos medibles y observables. Objetivo: identificar las concepciones y enfoques de la cultura física y el deporte en los diferentes momentos de la historia, planteados desde la lógica del modelo de la determinación social propio de la epidemiología crítica. Metodología: revisión sistemática que permite reconocer los conceptos, teorías y modelos planteados nacional e internacionalmente alrededor de las categorías cultura física y deporte, tomando como modelo de análisis la determinación social. Resultados: la cultura física es un concepto relacionado con el cuerpo, la cultura y el movimiento que no se reconoce en las bases de datos; por el contrario, se relaciona con términos de búsqueda como deporte, recreación y actividad física. No obstante, en algunos países la cultura física se considera como un conjunto de programas y acciones desarrollados desde las áreas del deporte, la recreación y la actividad física, la cual se incluye dentro de las políticas públicas y planes de gobierno. Discusión: en Colombia no hay claridad sobre el significado y la implementación de la cultura física, por esto, se hace necesario revisar este concepto, el cual se ha utilizado dentro los procesos de formación de los profesionales de cultura física, el deporte y la recreación. -- Physical culture and sport are categories that have been associated with physical activity and physical education throughout time while picking up different paradigms of knowledge. However, the prevailing paradigm has been the empirical and analytical view, which focuses only on measurable and observable phenomena. Objective: to identify the concepts and approaches

  12. Constituintes químicos, fenóis totais e atividade antioxidante de Sterculia striata St. Hil. et Naudin Chemical constituents, total phenolics and antioxidant activity of Sterculia striata St. Hil. et Naudin

    Directory of Open Access Journals (Sweden)

    Danielly Albuquerque Costa

    2010-03-01

    Full Text Available A investigação fitoquímica das cascas do caule de Sterculia striata St. Hil. et Naudin, através de métodos cromatográficos, conduziu ao isolamento dos esteróides sitosterol, estigmasterol e sitosterol-3-O-β-D-glicopiranosídeo, além de quatro triterpenóides pentacíclicos, o lupeol, 3-β-O-acil lupeol, lupenona e ácido betulínico. As estruturas desses compostos foram identificadas por análise dos espectros de RMN ¹H e 13C e comparações com dados da literatura. Para determinação do teor de fenóis totais do extrato etanólico de S. striata utilizou-se o reativo Folin Ciocalteu, enquanto na avaliação da atividade antioxidante empregou-se o radical livre DPPH. Este é o primeiro trabalho descrevendo o estudo químico com as cascas do caule desta espécie.The phytochemical investigation of the stem bark of Sterculia striata St. Hil. et Naudin by chromatographic methods led to the isolation of sitosterol, stigmasterol and sitosterol-3-O-β-D-glucopyranoside, besides pentacyclic triterpenoids, lupeol, 3-β-O-acyl-lupeol, lupenone and betulinic acid. The structures of these compounds were identified by ¹H and 13C NMR spectral data analysis and comparison with literature data. For determining of the phenolic content of the etanolic extract of Sterculia striata we used the Folin Ciocalteu reagent, and for the evaluation of antioxidant activity, we utilized the DPPH free radical. This is the first work reporting the chemical study with the stem bark of this species.

  13. On the molecular basis of the activity of the antimalarial drug chloroquine: EXAFS-assisted DFT evidence of a direct Fe-N bond with free heme in solution

    Science.gov (United States)

    Macetti, Giovanni; Rizzato, Silvia; Beghi, Fabio; Silvestrini, Lucia; Lo Presti, Leonardo

    2016-02-01

    4-aminoquinoline antiplasmodials interfere with the biocrystallization of the malaria pigment, a key step of the malaria parasite metabolism. It is commonly believed that these drugs set stacking π···π interactions with the Fe-protoporphyrin scaffold of the free heme, even though the details of the heme:drug recognition process remain elusive. In this work, the local coordination of Fe(III) ions in acidic solutions of hematin at room temperature was investigated by extended x-ray absorption fine structure (EXAFS) spectroscopy in the 4.0-5.5 pH range, both in the presence and in the absence of the antimalarial drug chloroquine. EXAFS results were complemented by DFT simulations in polarizable continuum media to model solvent effects. We found evidence that a complex where the drug quinoline nitrogen is coordinated with the iron center might coexist with formerly proposed adduct geometries, based on stacking interactions. Charge-assisted hydrogen bonds among lateral chains of the two molecules play a crucial role in stabilizing this complex, whose formation is favored by the presence of lipid micelles. The direct Fe-N bond could reversibly block the axial position in the Fe 1st coordination shell in free heme, acting as an inhibitor for the crystallization of the malaria pigment without permanently hampering the catalytic activity of the redox center. These findings are discussed in the light of possible implications on the engineering of drugs able to thwart the adaptability of the malaria parasite against classical aminoquinoline-based therapies.

  14. El fenómeno del pluralismo asistencial: una realidad por investigar The phenomenon of healthcare pluralism: a reality to be researched

    Directory of Open Access Journals (Sweden)

    Enrique Perdiguero

    2004-05-01

    Full Text Available El pluralismo asistencial y la utilización de las medicinas alternativas y complementarias (CAM son fenómenos de creciente interés en el ámbito internacional. El objetivo de este trabajo es aproximarnos a los estudios realizados sobre el pluralismo asistencial y las CAM en España. Tan sólo tenemos algunos estudios antropológicos, muy dispersos, y los datos que aportan las encuestas realizadas en Cataluña. Resulta urgente llevar a cabo estudios que nos permitan conocer la realidad de estos fenómenos en España y proponer políticas asistenciales que den seguridad a nuestra población en este ámbito.Medical pluralism and the uses of Complementary and Alternative Medicine (CAM are phenomena of increasing interest in the international arena. The aim of this chapter is to comment on Spanish studies dealing with medical pluralism and CAM. We have only a few scattered anthropological studies, and some data from surveys in Catalonia. There is an urgent need to carry out studies to ascertain the level of medical pluralism in Spain in order to develop care policies which provide assurance to the population in this area.

  15. Olvido de los fenómenos psicológicos en la relación médico-paciente anciano.

    Directory of Open Access Journals (Sweden)

    Carlos A. Reyes Ortiz

    2009-10-01

    Full Text Available Para evaluar las publicaciones sobre la relación médico-paciente anciano, se hizo una revisión sistemática de ese tema en el MEDLINE (1966-1995. Se buscaron los artículos de investigación que tenían que ver con los componentes de la relación médico-paciente anciano. De los 57 artículos que se incluyeron, 33% se enfocaban en las barreras actitudinales, 25% en los resultados, 23% en las capacidades de comunicación, 16% en asuntos éticos, y sólo 3% en los fenómenos psicológicos. Aspectos como la transferencia, la contratransferencia y la empatía son esenciales para entender la relación médico-paciente anciano. Se concluyó que los fenómenos psicológicos entre los médicos y sus pacientes ancianos a menudo no se incluyen en la investigación.

  16. La casa propia, un fenómeno en extinción. La “inquilinización” en la ciudad de Buenos Aires

    Directory of Open Access Journals (Sweden)

    María Carla Rodríguez

    2015-04-01

    Full Text Available En los últimos años, el alquiler formal e informal en la ciudad de Buenos Aires se ha convertido en una estrategia residencial empleada por los hogares de las capas medias y bajas para acceder a una vivienda. Este fenómeno se refleja en las estadísticas, pues en el año 2001 la población inquilina constituyó un 22,2% y hacia el 2010 aumentó a un 30%. Ante este escenario, el artículo propone abordar el proceso de “inquilinización” que toma fuerza durante la última década y toma en cuenta las características de la población involucrada y el rol del Estado y del mercado. Se utilizan datos estadísticos tomados del Censo Nacional de Población, Hogares y Vivienda 2001 y 2010 y la Encuesta Permanente de Hogares (Instituto Nacional de Estadísticas y Censos [Indec], 2010; 2012 como fuentes secundarias y primarias (datos testimoniales, con un enfoque de tipo cualitativo para interpretar los significados y las características que están detrás del fenómeno.

  17. Consumo e padronização de fármacos antihipertensivos na farmácia-ensino da Universidade Estadual de Maringá (FEN-UEM Distribution and standardization of antihypertensive medications in the pharmacy of State University of Maringá (FEN-UEM

    Directory of Open Access Journals (Sweden)

    Roberto Kenji Nakamura Cuman

    1999-07-01

    Full Text Available Com o objetivo de padronizar fármacos anti-hipertensivos na FEN-UEM, foram analisados a aquisição e o consumo desses fármacos. Os dados foram coletados a partir das notas fiscais de compra das especialidades farmacêuticas anti-hipertensivas (EAH pela referida farmácia. O estudo foi realizado no período de primeiro de janeiro de 1990 a trinta e um de dezembro de 1994. Foram analisados a quantidade de EAH adquirida, o princípio ativo e a classe farmacológica. A FEN - UEM adquiriu 4.751 EAH nesse período. Houve aumento na aquisição de inibidores da enzima conversora de angiotensina (63,6% e redução na de diuréticos (54,2%, bloqueadores beta-adrenérgicos (36,3%, agonistas alfa centrais (64,3% e associações (28,2%. A aquisição de bloqueadores de canais de cálcio foi constante nesse período. Os dados sugerem que a aquisição e a dispensação desses medicamentos estão correlacionadas com a terapêutica atual, permitindo avaliar o perfil de fármacos anti-hipertensivos na Farmácia-Ensino da UEM e padronizar as EAH a serem dispensadas pelas farmácias.With the objective of standardizing antihypertensive drugs in FEN-UEM, the acquisition and consumption of these drugs were analyzed. The data were collected starting from the invoices of purchase of the pharmaceutical antihypertensives specialties (EAH for the referred pharmacy. The study was carried out in the period of January 1st, 1990 trough December 31st 1994. The amount of acquired EAH, active substance and pharmacological class were analyzed. The FEN-UEM acquired 4,751 EAH in this period. There was increased in the acquisition of angiotensin-converting enzyme inhibitors (63,6% and reduction for diuretics (54,2%, beta-blockers (36,3%, alpha central agonists (64,3% and associations (28,2%. The acquisition of calcium antagonists was constant in this period. The data suggest that the acquisition and distribution of these medications are correlated with the current therapeutics

  18. O olhar dos psiquiatras brasileiros sobre os fenômenos de transe e possessão Brazilian psychiatrists’ approaches on trance and possession phenomena

    Directory of Open Access Journals (Sweden)

    Angélica A. Silva de Almeida

    2007-01-01

    Full Text Available CONTEXTO: Os fenômenos de transe e possessão despertaram o interesse da comunidade psiquiátrica brasileira, gerando posturas diversificadas. OBJETIVOS: Descrever e analisar como os fenômenos de transe e possessão foram tratados pelos psiquiatras brasileiros: seu impacto na teoria, na pesquisa e na prática clínica entre 1900 e 1950. MÉTODO: Análise de artigos científicos e leigos, teses e livros sobre transes e possessões produzidos pelos psiquiatras brasileiros entre 1900 e 1950. RESULTADOS: Identificam-se duas correntes de pensamento entre os psiquiatras. A primeira, vinculada às Faculdades de Medicina do Rio de Janeiro e São Paulo, sob forte influência de autores franceses, deteve-se mais na periculosidade do espiritismo para a saúde mental. Defendia a adoção de medidas repressivas com o poder público. O segundo grupo de psiquiatras, ligado às Faculdades de Medicina da Bahia e Pernambuco, embora não desconsiderasse o caráter patológico ou "primitivo" dos fenômenos de transe e possessão, apresentou uma visão mais antropológica e culturalista. Considerando tais fenômenos como manifestações étnicas ou culturais, alguns defenderam o controle médico e a educação do povo para o abandono dessas práticas "primitivas". Outros não consideravam os fenômenos mediúnicos como desencadeadores da loucura, mas manifestações não-patológicas de um universo cultural, além de não vinculá-los ao atraso cultural da população. CONCLUSÕES: As religiões mediúnicas foram objeto de estudo por longo período, resultando hipóteses e práticas diferenciadas por parte da comunidade psiquiátrica brasileira, constituindo-se oportunidade privilegiada para o estudo do impacto dos fatores socioculturais na atividade psiquiátrica.BACKGROUND: Trance and possession experiences have raised interest among Brazilian psychiatrists resulting in a variety of approaches. OBJECTIVES: To describe and analyze how Brazilian psychiatrists

  19. Long-term CO2 flux dynamics and soil C stock changes of a drained fen mire under different grassland management practices in Northeast Germany

    Science.gov (United States)

    Augustin, Juergen; Giebels, Michael; Albiac Borraz, Elisa; Hoffmann, Mathias; Sommer, Michael

    2014-05-01

    Fen mires, widely distributed in Germany and Northern Europe, contain extreme high amounts of carbon (up to 5000 t C per hectare). For this reason, they play an important role in the global cycle of the greenhouse gases carbon dioxide (CO2) and methane (CH4). Currently more than 95% of all fen mires in central Europe are drained. Therefore, they are assumed to represent extremely strong sources for CO2,accompanied by a fast reduction of the peat carbon stocks. For a number of reasons it is not possible to overcome this problem by restoration measures like flooding at the most drained fen sites. Moreover, there are till now just few and contradictory information about the contribution of alternative land use forms like grassland extensification on the reduction of the CO2 source function of these organic soils. As a contribution to clearing this deficit, we have ongoingly measured the CO2 and CH4 exchange as well as the changes in C stock on a deeply drained fen mire near the village of Paulinenaue from 2007 till 2012. The measurement sites is located within the so-called Rhin-Havelluch, an 80000 ha shallow paludification mire complex in the northwest of Berlin. The investigation included extensively and intensively used meadows (one cut vs. three cuts) on two soil types with different C stocks (Hemic Rheic Histosol vs. Mollic Gleysol). We used transparent chambers for measuring the CO2 flux net ecosystem exchange (difference between gross primary production and ecosystem respiration) and non-transparent chambers for measuring the CO2 flux ecosystem respiration and the CH4 exchange. Determined soil stock changes based on a C budget approach, including cumulated annual net ecosystem exchange, cumulated CH4 exchange, C export by harvest, and C import by fertilization. All current C fluxes were influenced in a complex way by ground-water level, plant development, land use intensity (cut frequency) and current weather conditions. Averaged over the whole investigation

  20. Microbiota dynamics related to environmental conditions during the fermentative production of Fen-Daqu, a Chinese industrial fermentation starter

    NARCIS (Netherlands)

    Zheng, Xiao-Wei; Yan, Zheng; Nout, M J Robert; Smid, Eddy J; Zwietering, Marcel H; Boekhout, Teun; Han, Jian-Shu; Han, Bei-Zhong

    2014-01-01

    Chinese Daqu is used as a starter for liquor and vinegar fermentations. It is produced by solid state fermentation of cereal-pulse mixtures. A succession of fungi, lactic acid bacteria and Bacillus spp. was observed during the production of Daqu. Mesophilic bacteria followed by fungi, dominated the

  1. Microbiota dynamics related to environmental conditions during the fermentative production of Fen-Daqu, a Chinese industrial fermentation starter

    NARCIS (Netherlands)

    Zheng, X.; Yan, Z.; Nout, M.J.R.; Smid, E.J.; Zwietering, M.H.; Boekhout, T.; Han, J.S.; Han, B.

    2014-01-01

    Chinese Daqu is used as a starter for liquor and vinegar fermentations. It is produced by solid state fermentation of cereal–pulse mixtures. A succession of fungi, lactic acid bacteria and Bacillus spp. was observed during the production of Daqu. Mesophilic bacteria followed by fungi, dominated the

  2. Degradation of pyrene and characterization of Saccharothrix sp. PYX-6 from the oligotrophic Tianchi Lake in Xinjiang Uygur Autonomous Region, China

    Institute of Scientific and Technical Information of China (English)

    HU Yuting; REN Fenghua; ZHOU Peijin; XIA Min; LIU Shuangjiang

    2003-01-01

    Bacterial strain PYX-6 that utilizes anthracene, phenanthrene, or pyrene for carbon and energy sources for growth was isolated from a non-polluted lake (Tianchi Lake) in Xinjiang Uygur Autonomons Region of China. Its morphology, physiological and biochemical properties, cell wall pattern and G+C mol% content of DNA molecules were characterized. The 16S rRNA gene of strain PYX-6 was sequenced and analyzed for similarities to related bacterial species. Results indicated that strain PYX-6 is a member of the Genus Saccharothrix, and the strain was named Saccharothrix sp. PYX-6. When pyrene was the sole carbon source in cultural medium, the strain PYX-6 assimilated pyrene for growth and 0.005% of yeast extract stimulated pyrene degradation and assimilation. The optimal pH of cultural medium and the optimal shaking frequency during cultivation were 6-8 and 200 r/m, respectively. It was found that the disappearance of pyrene in medium occurred before significant growth of strain PYX-6 took place. Phthalic acid, benzylacetic acid, and benzylpropenoic acid were detected as catabolic intermediates during pyrene degradation with mass spectroscopy and this result indicated that Saccharothrix sp. PYX-6 adopted a pathway that is different from the pathway of the previously reported pyrene-degrading Mycobacterium sp. PYR-1.

  3. Fenómeno miotónico orofacial en pacientes con distrofia miotónica de Steiner Orofacial myotonic phenomenon in Steiner´s myotonic dystrophy patients

    OpenAIRE

    Guimarães, A. S.; G.I. Suazo; S.K. Nagahashi Marie

    2010-01-01

    La distrofia miotónica de Steinert (DM1) es una enfermedad hereditaria, caracterizada por desórdenes multisistémicos asociados a disfunción muscular. Una de las manifestaciones clínicas más frecuentes es el fenómeno miotónico, en el cual se produce un enlentecimiento de la relajación muscular postisométrica. En este estudio analizamos la presencia del fenómeno miotónico (FM) en movimientos de apertura cierre oral, movimientos de la lengua y de otros músculos periorales, en 50 pacientes adulto...

  4. Panorama Epidemiológico de los Desastres Naturales. Ensayo a propósito del Fenómeno El Niño en el Perú (1998

    Directory of Open Access Journals (Sweden)

    Hernán Sanabria Rojas

    1998-01-01

    Full Text Available A manera de ensayo se hace una actualización de los conocimientos aceptados internacionalmente en relación a desastres. Se enfatiza en la última experiencia adquirida en el fenómeno El Niño en el Perú y su relación con las enfermedades infecciosas emergentes. Asimismo, se informa de algunas acciones y experiencias conexas al fenómeno realizadas por instituciones gubernamentales y no gubernamentales relacionadas con el sector salud.

  5. El multimétodo como estrategia fructífera para el abordaje de los fenómenos sociales: experiencias en la investigación de la pobreza

    OpenAIRE

    Elisa Sarrot; Graciela Mingo; César Sione

    2013-01-01

    Pretendemos valorizar la potencialidad de la estrategia multimétodo para el estudio de los fenómenos sociales, mediante la sistematización de las experiencias recogidas en la línea de investigación de la pobreza urbana. Sostenemos que el relato de las decisiones epistemológicas y metodológicas que nuestro equipo de investigación fue tomando para abordar la complejidad del fenómeno de la pobreza, resultará fructífero a otros investigadores. Por lo tanto, en este artículo asumen importancia ...

  6. El fenómeno del Palo de Hockey de las cadenas de suministro en empresas manufactureras: un análisis mediante dinámica de sistemas y experimentos de laboratorio

    OpenAIRE

    Mora Luna, Luz Adriana

    2013-01-01

    Resumen: Cuando es difícil alcanzar la utilidad mensual esperada, los minoristas suelen establecer un sistema de oferta de descuentos para incrementar la demanda del mercado, generándose una acumulación de pedidos al final del reporte mensual de ventas. Esta situación se conoce como el fenómeno del Palo de Hockey. A pesar que la generación de este fenómeno se ha descrito en la literatura desde hace varios años, hay poca investigación que estudie las posibles causas que generan su comportamien...

  7. Quantificação de compostos fenólicos e ácido ascórbico em frutos e polpas congeladas de acerola, caju, goiaba e morango

    OpenAIRE

    Juliana Mesquita Freire; Celeste Maria Patto de Abreu; Denise Alvarenga Rocha; Angelita Duarte Corrêa; Natália Rodrigues Marques

    2013-01-01

    O crescente interesse da população pela promoção da saúde vem despertando a atenção dos consumidores por alimentos ricos em antioxidantes, combinado com a praticidade do consumo de sucos de frutos processados. O presente trabalho objetivou quantificar e avaliar a capacidade antioxidante de compostos fenólicos e ácido ascórbico em frutas in natura e polpas congeladas. As frutas in natura e polpas congeladas obtidas na região de Lavras - MG foram submetidas à quantificação de compostos fenólico...

  8. Determinación de la composición fenólica en Vitis vinifera cv Albariño en la Denominación de Origen Rías Baixas

    OpenAIRE

    Zamuz Castro, Sol Ángel; Vilanova de la Torre, María del Mar; Masa Vázquez, Antón

    2009-01-01

    Durante tres años se ha estudiado (mediante HPLC-DAD) la composición fenólica de mostos de Albariño procedentes de tres subzonas de la D.O. Rías Baixas: O Condado do Tea, O Rosal y O Val do Salnés, pudiéndose separar y cuantificar 52 compuestos fenólicos que hemos agrupado en derivados hidroxibenzoicos, derivados hidroxicinámicos, estilbenos, flavan-3-oles, flavonoles y flavanoides. 44 de ellos han sido identificados. Se han encontrado diferencias significativas entre las tres subzonas geográ...

  9. Sobre los saberes culturales y el fenómeno "sentirse bien-sentirse mal" On cultural knowledge and the phenomenon "feel good-fell bad"

    Directory of Open Access Journals (Sweden)

    Virtudes Rodero Sánchez

    2010-09-01

    Full Text Available El objetivo del presente estudio es identificar los saberes culturales inmersos en el fenómeno "sentirse-bien, sentirse mal", en diferentes situaciones de cuidado. Se elaboró un estudio cualitativo con un enfoque fenomenológico interpretativo, mediante el análisis de 18 narrativas a partir de entrevistas en profundidad realizadas por alumnas del Máster en Ciencias de la Enfermería en diferentes contextos de cuidados. Las categorías identificadas fueron: (1 Cronicidad y concepto de sentirse bien-sentirse mal. En la cronicidad este concepto está íntimamente relacionado con la recuperación de las actividades de la vida diaria y es componente importante en la percepción individual del concepto "calidad de vida". (2 Momentos agudos de enfermedad y concepto de sentirse bien-sentirse mal. En el análisis de los relatos del paciente aparecieron aspectos esenciales del fenómeno "sentirse bien-sentirse mal" para aumentar la comprensión de aspectos universales de algunos de sus componentes. Destacar que el fenómeno está íntimamente relacionado con la recuperación de las actividades de la vida diaria, y es un mediador importante en la percepción individual del concepto "calidad de vida". El interés de cara al cuidado es distinguir sus componentes universales, contextualizarlos en la práctica, dentro de las singularidades que presenta cada persona, de modo que nos permita su potenciación. El resultado es un cambio en la experiencia sentida.The object of the present study is to identify cultural knowledges immersed in the feeling-well, feeling-bad phenomenon in different care settings. A qualitative study was undertaken using a phenomenological interpretation approach through a meta-analysis of 18 narratives of profound interviews undertaken by Nursing Science Master Degree Students in different care situations. The categories established were: (1 Chronicity and the concept of feeling well-feeling bad. In this category, this concept is

  10. Avaliação do teor de antioxidantes, flavonoides e compostos fenólicos em preparações condimentares

    Directory of Open Access Journals (Sweden)

    G.M. MENDES

    2015-06-01

    Full Text Available RESUMO:Plantas condimentares são amplamente utilizadas na culinária como alimento funcional. Pacientes hipertensos, que retiram o sal de cozinha (NaCl de sua alimentação, relatam que os alimentos "perdem" o sabor. Visando alternativas para substituir o sal e melhorar a palatabilidade das preparações alimentares de pacientes hipertensos, o objetivo deste estudo foi desenvolver temperos à base de plantas medicinais e analisar os teores de compostos fenólicos, flavonoides e atividade antioxidante destes. Plantas (coentro, salsa, orégano, alecrim, manjericão, alho, cebola cultivadas organicamente em Viçosa (MG foram processadas e os temperos foram desenvolvidos a partir de combinação destas espécies, de acordo com teste aceitabilidade sensorial afetivo por meio de escala hedônica. Foram definidos três temperos, dos quais foram feitos extratos metanólicos por remaceração até esgotamento. Nas dosagens utilizou-se DPPH na avaliação da atividade antioxidante; reagente de Folin-Ciocalteu para compostos fenólicos e vanilina clorídrica para flavonoides. As análises foram feitas com quatro repetições e os resultados submetidos à análise de variância e teste de média a 5% de significância. Na aceitação subjetiva dos temperos a nota média foi 7,07±1,09 e 8,0±0,93 na ação afetiva como alimento. O teor mais elevado de compostos fenólicos foi no tempero 2 (alho, salsa e manjericão (55,04±4,307 mg/mL, a maior ação antioxidante foi no tempero 1 (alho, cebola, coentro e orégano nos tempos 0 (48,72% e 30 minutos (78,37%. Os teores de flavonoides foram semelhantes nos 3 temperos. Todos os temperos tiveram boa aceitação por pacientes hipertensos e mostraram-se promissores na substituição dos condimentos convencionais.

  11. El fenómeno MOOC y la universalidad de la cultura: las nuevas fronteras de la educación superior

    Directory of Open Access Journals (Sweden)

    Jose Gómez Galán

    2014-01-01

    Full Text Available Este artículo tiene como principal objetivo ofrecer una explicación a la rápida extensión del fenómeno MOOC –y su verdadera relevancia y posición en la Educación Superior– en el contexto de las dinámicas postmodernas de universalidad de la cultura, la comunicación y el conocimiento. Analiza, por medio de una metodología crítico-teórica y ex post facto, cómo los cursos MOOC representan una parte de la integración del mundo universitario en los complejos procesos de globalización propiciados por la revolución de las TIC, pero concluye que en modo alguno significan la última frontera de la Educación Superior. Como resultados más importantes se determina que contribuyen en cierta media a [1] una universalidad de la cultura, ubicándose dentro del fenómeno de la globalización y lo que hoy ésta representa, [2] la universalidad de la comunicación, en el seno de la convergencia tecno-mediática, [3] la universalidad del conocimiento, con el empleo de pedagogías y metodologías didácticas extendidas de modo global y, en definitiva, [4] la universalidad de la propia Educación Superior, partícipes de los procesos de homogenización de los modelos de estudios universitarios y de adaptación a las características de una sociedad en red. Pero no suponen un fenómeno de tal envergadura que lleve a una transformación radical de este nivel educativo. Ni siquiera ofrecen innovaciones pedagógicas y didácticas significativas en relación con lo ya aportado previa y paralelamente por otros procesos de e-learning. Significan tan sólo una de las muchas respuestas –en absoluto la única– a las nuevas necesidades sociales, en un contexto de formación para todos y durante toda la vida, lo que explica su eclosión.

  12. Constituintes fenólicos e terpenóides isolados das raízes de Andira fraxinifolia (Fabaceae

    Directory of Open Access Journals (Sweden)

    Virginia Claudia da Silva

    2006-12-01

    Full Text Available Sitosterol, stigmasterol, betulinic acid, lupeol, 3-O-beta-D-glucopiranosylsitosterol, 3-O-alpha-L-rhamnopiranosylchromone, 5,7-dihydroxy-4'-methoxyisoflavone, 3',5,7-trihydroxy-4'-methoxyisoflavone and a mixture of two rel-2R,3S-3-O-alpha-L-rhamnopiranosilflavanonols were isolated from the roots of Andira fraxinifolia. Their structures were established by spectral data analysis.

  13. Folic Acid

    Science.gov (United States)

    Folic acid is a B vitamin. It helps the body make healthy new cells. Everyone needs folic acid. For women who may get pregnant, it is really important. Getting enough folic acid before and during pregnancy can prevent major birth ...

  14. Characterization of the bio-optical anomaly and diurnal variability of the particulate matter, as seen from the scattering and backscattering coefficients, in ultra-oligotrophic eddies of the Mediterranean Sea

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    H. Loisel

    2011-08-01

    Full Text Available The variability of the inherent optical properties is investigated in the ultra-oligotrophic waters of the Mediterranean Sea sampled during the BOUM experiment performed during the early summer 2008. Bio-optical relationships found for the ultra-oligotrophic waters of the three anticyclonic gyres sampled significantly depart from the mean standard relationships provided for the global ocean, confirming the particular character of these Mediterranean waters. These optical anomalies are diversely related to the specific biological and environmental conditions occurring in the studied ecosystem. Specifically, the surface specific phytoplankton absorption coefficient exhibits values lower than those expected from the general relationships mainly in relation with a high contribution of relatively large sized phytoplankton. Conversely, the particulate backscattering coefficient, bbp, values are much higher than the mean standard values for a given chlorophyll-a concentration, TChl-a. This feature can presumably be related to the relevant influence of highly refractive submicrometer particles of Saharan origin in the surface layer of the water column. The present measurements also show that the Mediterranean Sea is greener than TChl-a alone indicates, as already stressed in previous studies. This color anomaly is partly explained by the estimated colored dissolved organic matter and submicrometer particles absorption coefficients, and to a greater extent by the high bbp/TChl-a values assuming that these particles backscatter light similarly in the green and blue parts of the visible spectrum. The diel variation of both the particulate matter attenuation and backscattering coefficients were also investigated specifically. Despite some differences in the timing and the magnitude of the daily oscillations found for these optical parameters, potential for the backscattering coefficient daily

  15. Amino acids

    Science.gov (United States)

    ... amino acids are: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan , and valine. Nonessential amino acids "Nonessential" means that our bodies produce an amino ...

  16. Estudio de la maduración fenólica y antociánica en uvas tintas de bobal para diferentes condiciones agrológicas

    OpenAIRE

    Méndez Sánchez, José Vicente

    2008-01-01

    En este trabajo se ha estudiado el comportamiento agronómico de la variedad Bobal, a través del seguimiento de su maduración en diferentes condiciones agrológicas y con aportes hídricos diferenciados. También se han ensayado varios sistemas de evaluación del contenido antociánico y fenólico en uvas, y se han correlacionado los contenidos en las uvas con los contenidos finales de los vinos que se han elaborado. El máximo contenido antociánico se aprecia veinte días después del envero en t...

  17. Filtre à fenêtre glissante pour l'estimation de l'attitude et des vitesses d'un projectile

    OpenAIRE

    Grandvallet, Bertrand; Zemouche, Ali; Boutayeb, Mohamed; Changey, Sébastien

    2010-01-01

    National audience Ce papier traite du problème de guidage d'un projectile stabilisé par rotation. Nous apportons une contribution au niveau la navigation grâce à des capteurs ”bas-coût” de type accéléromètres et magnétomètres. Les fortes non-linéarités présentes dans les équations d'états (dynamique et sortie) du modèle nous restreignent à l'utilisation de peu de méthodes d'estimation. Nous proposons ici un Filtre de Kalman Etendu (FKE) utilisant une fenêtre glissante sur les mesures pour ...

  18. Fenóis derivados da lignina, carboidratos e aminoaçúcares em serapilheira e solos cultivados com eucalipto e pastagem

    OpenAIRE

    Rodinei Facco Pegoraro; Ivo Ribeiro da Silva; Roberto Ferreira Novais; Nairam Felix de Barros; Sebastião Fonseca

    2011-01-01

    O cultivo de espécies florestais como o eucalipto em solos ocupados por pastagens pode levar a alterações no processo de decomposição de resíduos vegetais e na formação da matéria orgânica do solo (MOS), principalmente por alterar a contribuição de diferentes compostos orgânicos e modificar a atividade e a diversidade microbiana. Neste sentido, o presente estudo teve o objetivo de avaliar alterações causadas pelo cultivo do eucalipto em compostos orgânicos, tais como: fenóis derivados de lign...

  19. El (neo)tango en París : Acerca de un fenómeno paradójico en su espaciamiento y temporalización

    OpenAIRE

    Kailuweit, Rolf

    2008-01-01

    Basándose en los conceptos derridianos del espaciamiento y temporalización, y en la actual discusión acerca del "giro espacial", la presentación se ocupará del renacimiento del tango en París en las últimas dos décadas. Se abordará, entre otros aspectos, la posición lemática del grupo Gotan Project y el desarrollo de la escena milonguera en la capital francesa tal como la describen Remi Hess y Christophe Apprill. Se planteará la pregunta hasta qué punto el tango se ha vuelto un fenómeno entró...

  20. Bibliotecas públicas e ciberviolência em tempos de uma sociedade em rede: Novos papéis diante de um novo fenômeno

    OpenAIRE

    Rubens da Silva Ferreira; Telma Socorro da Silva Sobrinho

    2012-01-01

    Reflete sobre o papel das bibliotecas públicas na educação de usuários para o conhecimento da ciberviolência. Tal fenômeno é expresso através das Tecnologias de Informação e Comunicação (TIC), as quais são utilizadas para causar danos às vítimas. O trabalho fundamenta-se em três casos de ciberviolência: um de homicídio; um de estelionato e um de pedofilia. Os casos dão sustentação à reflexão sobre a necessidade de intervenção das bibliotecas públicas. O quadro teórico que serve a análise cons...

  1. Bibliotecas públicas e ciberviolência em tempos de uma sociedade em rede: novos papéis diante de um novo fenômeno

    OpenAIRE

    Silva Ferreira, Rubens; Silva Sobrinho, Telma Socorro da

    2012-01-01

    Reflete sobre o papel das bibliotecas públicas na educação de usuários para o conhecimento da ciberviolência. Tal fenômeno é expresso através das Tecnologias de Informação e Comunicação (TIC), as quais são utilizadas para causar danos às vítimas. O trabalho fundamenta-se em três casos de ciberviolência: um de homicídio; um de estelionato e um de pedofilia. Os casos dão sustentação à reflexão sobre a necessidade de intervenção das bibliotecas públicas. O quadro teórico que serve a análise cons...

  2. Violência doméstica e enfermagem: da percepção do fenômeno à realidade cotidiana

    OpenAIRE

    Salcedo-Barrientos, Dora; Gonçalves, Luz; Oliveira Junior, Mauricio; Egry, Emi

    2012-01-01

    A violência decorre dos conflitos de autoridade, das lutas de poder, da vontade de domínio, do desejo de aniquilação dos outros e de seus bens. É importante considerar os impactos que os casos de violência têm na sociedade. O estudo teve como objetivo a identificação da percepção dos enfermeiros de Atenção Básica sobre o fenômeno da violência doméstica e sua relação com as famílias. Foi um estudo prospectivo, descritivo e exploratório, de abordagem qualitativa, e sustentada pela Teoria de Int...

  3. Contrastes epistemológicos del binomio de Newton y la serie de Taylor en dos variables en los fenómenos físicos

    OpenAIRE

    Hernández, Hipólito

    2005-01-01

    En esta investigación presentamos elementos de análisis a través de los contrastes epistemológicos desde diferentes planos, para lo cual revisamos textos vigentes de álgebra, cálculo, física, textos de difusión de antaño, revisión del origen del binomio de Newton y la serie de Taylor. En estos contrastes observamos que los contenidos y los fenómenos físicos están descontextualizados de las prácticas sociales. También, permite ver que la noción de variación y de predicción, en tanto a práctica...

  4. O fenômeno da mutação constitucional e sua repercussão no controle de constitucionalidade: abordagem a partir de caso concreto

    OpenAIRE

    Correa, Camila Barela

    2014-01-01

    A pesquisa tem como objetivo analisar o fenômeno da mutação constitucional e sua repercussão no processo de controle de constitucionalidade. Buscar-se--á apresentar de que modo as teorias hermenêuticas têm influenciado na definição e alcance das normas jurídicas, em especial na interpretação das normas infraconstitucionais, que devem guardar parâmetro com a Constituição de 1988. Destacar-se-á o papel exercido pelo Supremo Tribunal Federal, por ser este o “guardião” da Constituição e, legitima...

  5. 汾酒在贮存过程中酒体陈酿行为的研究%Research of Fen liquor aging behaviors during storage time

    Institute of Scientific and Technical Information of China (English)

    任宏彬; 魏瑞霞; 张燕飞; 李美萍; 胡永钢; 张生万

    2015-01-01

    Objective To study the Fen liquor aging behaviors during storage time.Methods The content of Fen liquor main aroma components of different storage time was analyzed by gas chromatography internal standard method. Part of chemical equilibrium relations among aroma compositions were analyzed in quantity ratio relationship and the pH values and conductivities were measured. The model was established by multiple linear regression and its stability was tested by partial least square.Results A model of Fen liquor aging behaviors and storage time was established,Y=-5.096+3.196X1+4.815X2+1.801X3-0.1X4+0.124X5. The correlation coefficients of multiple linear regression and partial least squares model were 0.998 and 0.994, and the standard deviations were 0.573 and 0.732.ConclusionThe model had a good stability and specific physical meanings. It expressed that “esterification hydrolysis, dissolved oxygen oxidation, aldol condensation, low boiling point substances volatilization and metal ions participation” were the aging behaviors of Fen liquor.%目的:研究汾酒在贮存过程中酒体的陈酿行为。方法采用气相色谱内标法测定不同贮存时间酒样的主体香气成分含量;对其中存在化学平衡关系的香气成分进行量比关系的分析;测定酒样的 pH 值和电导率;利用多元线性回归建立模型,偏最小二乘法对模型的稳定性进行检验。结果建立了能反映汾酒陈酿行为与贮存时间的相关模型, Y=-5.096+3.196X1+4.815X2+1.801X3-0.1X4+0.124X5。多元线性回归与偏最小二乘法建模相关系数分别为0.998和0.994,标准偏差分别为0.573和0.732。结论所建模型稳定性良好,物理意义明确,表现出“酯化水解,溶解氧氧化,醇醛缩合,低沸点物质挥发,金属离子参与”是汾酒的主要陈酿行为。

  6. O fenômeno das drogas e as macro-políticas – agências e tratados internacionais

    Directory of Open Access Journals (Sweden)

    Telma Elisa Carraro

    2004-01-01

    Full Text Available El artículo trata sobre la cuestión de las macro políticas relacionados al fenómeno de las drogas, procurando la inserción del tema en el escenário internacional. Registra los principales organismos internacionales que se envolucran con el problema, señalando sus historias y sus acciones. Destaca la actuación de la Organización de los Estados Americanos – OEA y la formación de la Comisión Interamericana para el Control del Abuso de Drogas – CICAD, integrada por los Estados miembros de la OEA.

  7. Full GHG balance of drained fen peatland cropped to spring barley and reed canary grass using comparative assessment of CO2 fluxes

    DEFF Research Database (Denmark)

    Karki, Sandhya; Elsgaard, Lars; Kandel, Tanka Prasad;

    2015-01-01

    Empirical greenhouse gas (GHG) flux estimates from diverse peatlands are required in order to derive emission factors for managed peatlands. This study on a drained fen peatland quantified the annual GHG balance (Carbon dioxide (CO2), nitrous oxide (N2O), methane (CH4), and C exported in crop yield......) from spring barley (SB) and reed canary grass (RCG) using static opaque chambers for GHG flux measurements and biomass yield for indirectly estimating gross primary production (GPP). Estimates of ecosystem respiration (ER) and GPP were compared with more advanced but costly and labor-intensive dynamic...... chamber studies. Annual GHG balance for the two cropping systems was 4.0 ± 0.7 and 8.1 ± 0.2 Mg CO2-Ceq ha−1 from SB and RCG, respectively (mean ± standard error, n = 3). Annual CH4 emissions were negligible (

  8. Teores de antocianinas, fenóis totais, taninos e ácido ascórbico em uva 'bordô' sobre diferentes porta-enxertos

    OpenAIRE

    Maria Suzana Vial Pozzan; Gilberto Costa Braga; Ariane Busch Salibe

    2012-01-01

    Este trabalho teve como objetivo avaliar o conteúdo de antocianinas, fenóis totais, taninos e ácido ascórbico, em variedade de uva 'Bordô', cultivada sobre os porta-enxertos '420A', 'IAC-766' e 'Ripária-do-Traviú', em três períodos de colheita distintos. O experimento foi realizado em vinhedo de uva 'Bordô', no município de Missal, no Oeste do Paraná, na safra 2007/2008. O efeito dos porta-enxertos foi avaliado em três períodos de colheita, a partir da época de floração: 90 dias, com bagas em...

  9. Sexismo y opinión pública: estudio del fenómeno de desindividualización en la Red

    Directory of Open Access Journals (Sweden)

    María Eugenia Sanz Aniceto

    2015-01-01

    Full Text Available Se considera, en la actualidad, que nuestra sociedad está a favor del principio de igualdad, habiéndose erradicado o al menos desparecido en su práctica totalidad estereotipos y prejuicios hacia las mujeres. Sin em- bargo, en el presente estudio realizado a través del análisis de los comen- tarios realizados en el perfil oficial de Twitter del movimiento feminista Femen España, se pondrá de manifiesto como por parte de la opinión pública, existe de forma latente sexismo hacia las mujeres, favorecido en parte por el proceso comunicativo en las plataformas sociales en la Red, caracterizado por fenómenos de anonimato y desindividualización.

  10. Reflexiones sobre la presencia de regularidades en los fenómenos sociales y sobre la posibilidad de investigarlas desde un monismo metodológico

    Directory of Open Access Journals (Sweden)

    Héctor Salas Harms

    2008-01-01

    Full Text Available La historia de la ciencia perfila un orden temporal en el que la evolución de las disciplinas y aun la de sus especialidades ha culminado en su maduración científica; también perfila un orden en el cual sus teorías han alcanzado precisión al explicar y predecir sus fenómenos. Tal orden corresponde a la complejidad de los eventos que estudian esos campos del conocimiento; actualmente, madurez y precisión son característicos solamente en las ciencias naturales Las disciplinas sociales están hoy aún en una etapa pre-paradigmática, pre-científica, con disensión en sus comunidades de investigación aun sobre la índole de los hechos sociales: el dualismo metodológico piensa que en la naturaleza hay uniformidad y leyes universales, pero que los eventos humanos deben sólo comprenderse e interpretarse casuísticamente; por su parte, el monismo metodológico busca discernir y explicar regularidades mediante pruebas de hipótesis, modelos causales, rigor metodológico y resultados generalizables y replicables. Este texto presenta algunos hechos y regularidades en administración y en economía que pueden establecerse como ciertos y válidos para todo investigador. Asimismo, se muestra cómo pueden definirse mediante análisis ex ante los determinantes de diversos fenómenos sociales, inclusive de aquéllos cuyas variables no son susceptibles de ser cuantificadas.

  11. Fluxes and 13C isotopic composition of dissolved carbon and pathways of methanogenesis in a fen soil exposed to experimental drought

    Directory of Open Access Journals (Sweden)

    C. Blodau

    2008-10-01

    Full Text Available Peatlands contain a carbon stock of global concern and significantly contribute to the global methane burden. The impact of drought and rewetting on carbon cycling in peatland ecosystems is thus currently debated. We studied the impact of experimental drought and rewetting on intact monoliths from a temperate fen over a period of ~300 days, using a permanently wet treatment and two treatments undergoing drought for 50 days. In one of the mesocosms, vegetation had been removed. Net production of CH4 was calculated from mass balances in the peat and emission using static chamber measurements. Results were compared to 13C isotope budgets of CO2 and CH4 and energy yields of acetoclastic and hydrogenotrophic methanogenesis. Drought retarded methane production after rewetting for days to weeks and promoted methanotrophic activity. Based on isotope and flux budgets, aerobic soil respiration contributed 32–96% in the wet treatment and 86–99% in the other treatments. Drying and rewetting did not shift methanogenic pathways according to δ13C ratios of CH4 and CO2. Although δ13C ratios indicated a prevalence of hydrogenotrophic methanogenesis, free energies of this process were small and often positive on the horizon scale. This suggests that methane was produced very locally. Fresh plant-derived carbon input apparently supported respiration in the rhizosphere and sustained methanogenesis in the unsaturated zone, according to a 13C-CO2 labelling experiment. The study documents that drying and rewetting in a rich fen soil may have little effect on methanogenic pathways, but result in rapid shifts between methanogenesis and methanotrophy. Such shifts may be promoted by roots and soil heterogeneity, as hydrogenotrophic methanogenesis occurred locally even when conditions were not conducive for this process in the bulk peat.

  12. Efecto de los componentes del agua de mar durante el fenómeno de corrosión por picaduras del cobre

    Directory of Open Access Journals (Sweden)

    García, E.

    1995-10-01

    Full Text Available Copper is the main component in Cu-Ni alloys recommended for sea water applications. This work presents the electrochemical behaviour of copper in presence of different sea water components and its influence on the corrosion attack. The combined action of chloride and sulphate ions are the main responsible factor for the localized corrosion attack in the form of pitting. A significant parabolic relation exists between the critical pitting potential (Ep and the weight ratio of chloride to sulphate (Cl-/SO42- ions. Therefore sulphate ions are an important component for pitting corrosion of copper.

    El cobre es el elemento principal de las aleaciones Cu-Ni recomendadas para aplicaciones marinas. En este trabajo se presenta el comportamiento electroquímico del cobre con los diferentes componentes del agua de mar y el efecto de estos sobre la forma de ataque del cobre. Se observó que los iones cloruro, en unión con los iones sulfato, son los principales causantes del fenómeno de corrosión por picaduras, existiendo, además, una relación significativa entre el potencial crítico de picado (Ep y la relación (Cl-/SO42- de tipo parabólico, lo cual pone de manifiesto la importancia del ion sulfato en el fenómeno de corrosión por picaduras como promotor de este tipo de mecanismo.

  13. Caracterización de los subproductos de la industria vitivinícola como fuente de fibra dietética y compuestos fenólicos. Uso de los ultrasonidos de potencia para la extracción de la fracción fenólica

    OpenAIRE

    González-Centeno, Mª Reyes

    2013-01-01

    El presente trabajo tiene como objetivo general evaluar el uso de los subproductos de vinificación, orujo y raspón, como fuentes de fibra dietética y compuestos fenólicos. Para ello se plantearon tres líneas de investigación, la primera de las cuales se centra en el estudio de las indicaciones vitivinícolas de las Islas Baleares en vistas a determinar sus características diferenciales consecuencia del entorno geográfico. Una vez reconocida dicha diferenciación y, consecuentemente, la diferenc...

  14. Control of brown spot pathogen of rice (Bipolaris oryzae using some phenolic antioxidants Controle da macha-parda do arroz (Bipolaris oryzae pelo emprego de antioxidantes fenólicos

    Directory of Open Access Journals (Sweden)

    Y.M. Shabana

    2008-09-01

    Full Text Available Bipolaris oryzae is the causal agent of rice brown spot disease and is responsible for significant economic losses. In order to control this disease, three phenolic antioxidants were tested (salicylic acid, benzoic acid and hydroquinone. The antifungal activity of the tested substances were investigated against B. oryzae at different concentrations in vitro, as well as the efficacy of their exogenous application in controlling rice brown spot disease under field conditions. In vitro, benzoic acid or salicylic acid at 9 mM completely inhibited the growth of B. oryzae. Under field conditions, spraying of benzoic acid at 20 mM led to a significant reduction in disease severity (DS and disease incidence (DI on the plant leaves, in addition to a significant increase in the grain yield and its components. Some biochemical responses were also detected, where the application of the previous treatment led to a significant increase in the total photosynthetic pigments (chlorophyll a and b and carotenoids in rice leaves and in the total carbohydrate and protein contents of the yielded grains.Bipolaris oryzae é o agente causador da doença mancha-parda do arroz e é responsável por significativas perdas econômicas. Três antioxidantes fenólicos (ácido salicílico, ácido benzóico e hidroquinona foram avaliados para o controle dessa doença do arroz. A atividade antifúngica destes compostos foi avaliada in vitro contra B. oryzae em diferentes concentrações e a eficiência de sua aplicação exógena no controle da mancha-parda foi avaliada em condições de campo. Nos ensaios in vitro, os ácidos benzóico e salicílico a 9 mM inibiram completamente a multiplicação de B. oryzae. Em condições de campo, a aspersão de ácido benzóico a 20 mM causou uma redução significativa na gravidade e incidência da doença na folhas da planta, além de aumentar significativamente o rendimento dos grãos e seus componentes. Algumas respostas bioqu

  15. Longimicrobium terrae gen. nov., sp. nov., an oligotrophic bacterium of the under-represented phylum Gemmatimonadetes isolated through a system of miniaturized diffusion chambers.

    Science.gov (United States)

    Pascual, Javier; García-López, Marina; Bills, Gerald F; Genilloud, Olga

    2016-05-01

    A novel chemo-organoheterotroph bacterium, strain CB-286315T, was isolated from a Mediterranean forest soil sampled at the Sierra de Tejeda, Almijara and Alhama Natural Park, Spain, by using the diffusion sandwich system, a device with 384 miniature diffusion chambers. 16S rRNA gene sequence analyses identified the isolate as a member of the under-represented phylum Gemmatimonadetes, where 'Gemmatirosa kalamazoonensis' KBS708, Gemmatimonas aurantiaca T-27T and Gemmatimonas phototrophica AP64T were the closest relatives, with respective similarities of 84.4, 83.6 and 83.3 %. Strain CB-286315T was characterized as a Gram-negative, non-motile, short to long rod-shaped bacterium. Occasionally, some cells attained an unusual length, up to 35-40 μm. The strain showed positive responses for catalase and cytochrome-c oxidase and division by binary fission, and exhibited an aerobic metabolism, showing optimal growth under normal atmospheric conditions. Strain CB-286315T was also able to grow under micro-oxic atmospheres, but not under anoxic conditions. The strain is a slowly growing bacterium able to grow under low nutrient concentrations. Major fatty acids included iso-C17 : 1ω9c, summed feature 3 (C16 : 1ω7c and/or iso-C15 : 0 2-OH), C16 : 0 and iso-C17 : 0. The major polar lipids were phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, two unidentified glycolipids and three phospholipids. The major isoprenoid quinone was MK-8 and the diagnostic diamino acid was meso-diaminopimelic acid. The DNA G+C content was 67.0 mol%. Based on a polyphasic taxonomic characterization, strain CB-286315T represents a novel genus and species, Longimicrobium terrae gen. nov., sp. nov., within the phylum Gemmatimonadetes. The type strain of Longimicrobium terrae is strain CB-286315T ( = DSM 29007T = CECT 8660T). In order to classify the novel taxon within the existing taxonomic framework, the family Longimicrobiaceae fam. nov., order

  16. Estudios de Criminología: Criminología y Derecho Penal ante los nuevos fenómenos delictivos. Primeras jornadas de criminología de las Universidades de Madrid

    OpenAIRE

    Ropero Carrasco, Julia

    2015-01-01

    I Jornadas de Criminología de las Universidades de Madrid, con el título "Criminología y Derecho Penal ante los nuevos fenómenos delictivos. Prevención y tratamiento". Celebradas en marzo de 2015 en la Universidad Rey Juan Carlos

  17. Fatores implicados no fenómeno de bullying em contexto escolar: revisão integrada da literatura Factores implicados en el fenómeno de acoso en contexto escolar: revisión integrada de la literatura Factors related to the bullying phenomenon in school context: integrative literature review

    Directory of Open Access Journals (Sweden)

    Rita Lopez

    2011-12-01

    Full Text Available As evidências científicas sugerem que o bullying é um fenómeno cada vez mais frequente no contexto escolar, ao qual está inerente um vasto número de consequências para a saúde, pelo que, a sua prevenção deve constituir uma área prioritária. Com o objetivo de identificar os fatores implicados no fenómeno do bullying em contexto escolar, efetuou-se uma revisão da literatura de forma sistematizada na Biblioteca do Conhecimento Online (b-on com as seguintes palavras-chave: “bullying/bullying school context”, considerando os seguintes critérios de inclusão: participantes (estudantes do 2º e 3º ciclo; variáveis em estudo (fatores implicados no fenómeno do bullying, sem restrições relativas ao desenho dos estudos. Foram identificados 351 artigos, dos quais não foi possível aceder a 132. Considerando os critérios de inclusão, foram eliminados 203 artigos, os restantes 16 foram analisados. Da análise dos resultados dos estudos que integram esta revisão da literatura, emergem quatro tipologias de fatores, os fatores relacionados com as variáveis sociodemográficas, os fatores relacionados com as variáveis pessoais, os relativos à dimensão familiar e ainda os relacionados com as variáveis escolares. Em função destas tipologias, identificaram-se diversos fatores protetores e fatores de risco implicados no fenómeno de bullying.Las evidencias científicas sugieren que el acoso es un fenómeno cada vez más frecuente en el contexto escolar, al cual está inherente un vasto número de consecuencias para la salud, por lo que su prevención debe constituir un área prioritaria. Con el objetivo de identificar a los factores implicados en el fenómeno del acoso en contexto escolar, se efectuó una revisión de la literatura de forma sistematizada en la “Biblioteca do Conhecimento Online” (b-on con las siguientes palabras clave: “bullying/bullying school context”, considerando los siguientes criterios de inclusi

  18. High School Student's Alternative Conceptions About the Phenomenon of the Formation of the Moon Phases. (Spanish Title: Concepciones Alternativas de Alumnos de Educación Media Sobre el Fenómeno de Formación de las Fases de La Luna.) Concepções Alternativas de Alunos do Ensino Médio Sobre o Fenômeno de Formação das Fases da Lua

    Science.gov (United States)

    Iachel, Gustavo; Langhi, Rodolfo; Fernandes Scalvi, Rosa Maria

    2008-07-01

    Forty students, at ages between 14 and 18 years old, from three schools in Bauru city, were questioned about their alternative conceptions concerning the phenomenon of formation of the Moon Phases. It was observed that some of the pupils confound the phenomenon of the formation of the Moon Phases with the phenomenon of the formation of the lunar eclipses, others are unaware of the reason of the phenomenon, they present incoherent alternative conceptions of the reality or incomplete conceptions. The results found here are aimed at the teachers of Elementary Education and can be used as a subsidy for future development of new pedagogical methods. Cuarenta estudiantes, con edad entre 14 y 18 años, pertenecientes a tres escuelas de la ciudad de Bauru, fueron cuestionados sobre sus concepciones alternativas acerca del fenómeno de la formación de las fases de la Luna. Fue observado que algunos alumnos confunden el fenómeno de formación de las fases de la Luna con el fenómeno de formación de los eclipses lunares, otros desconocen el motivo delfenómeno, presentan concepciones alternativas incoherentes con la realidad o bien presentan concepciones incompletas. Los resultados aquí encontrados son destinados a los profesores de la Enseñanza Básica y podrán ser usados como ayuda para el futuro desarrollo de nuevos métodos pedagógicos. Quarenta estudantes, com idades entre 14 e 18 anos, pertencentes a três escolas da cidade de Bauru, foram questionados sobre suas concepções alternativas acerca do fenômeno de formação das fases da Lua. Foi observado que alguns dos alunos confundem o fenômeno da formação das fases da Lua com o fenômeno da formação dos eclipses lunares, outros desconhecem o motivo do fenômeno, apresentam concepções alternativas incoerentes com a realidade ou então concepções incompletas. Os resultados aqui encontrados são destinados aos professores do Ensino Básico e poderão ser usados como subsídio parafuturo desenvolvimento de

  19. Viruses in a deep oligotrophic sea: Seasonal distribution of marine viruses in the epi-, meso- and bathypelagic waters of the Eastern Mediterranean Sea

    Science.gov (United States)

    Magiopoulos, Iordanis; Pitta, Paraskevi

    2012-08-01

    Marine viruses and their main hosts were studied in the Eastern Mediterranean Sea (Ionian, Libyan and Aegean Seas) during two sampling cruises (mixing and water column stratification periods). Samples were collected from the surface to 4000 m depth. Total abundance of viruses and prokaryotes was determined by Flow Cytometry (FCM). Viruses were separated into three groups according to their fluorescence signal. Viral abundance ranged from 1.2×105 viruses ml-1 to 2.7×107 viruses ml-1 and varied significantly between areas, depth zones and seasons. Prokaryotic cell abundance varied from 1.7×104 cells ml-1 to 1.5×106 cells ml-1 presenting a strong positive correlation with viral abundance. Stations and depths influenced by the Black Sea Water in the North Aegean Sea presented the highest values of viral abundance and Viruses to Prokaryotes Ratio (VPR). Vertical distributions of VPR were attributed to different water masses. The increased viral abundance and VPR values that were detected during the stratification period may be explained by the seasonal changes in prokaryotic cell characteristics (cell size, nucleic acid content). These significant seasonal distributions were also found below 1000 m indicating a possible viral activity in the bathypelagic ocean.

  20. Phenolic compounds, carotenoids and antioxidant activity in plant products / Compostos fenólicos, carotenóides e atividade antioxidante em produtos vegetais

    Directory of Open Access Journals (Sweden)

    Maria Gabriela Bello Koblitz

    2010-09-01

    variedade de doenças crônicas como aterosclerose e câncer, efeitos que têm sido particularmente atribuídos aos compostos que possuem atividade antioxidante nos vegetais: vitaminas C e E, os compostos fenólicos, especialmente os flavonóides, e os carotenóides. Compostos fenólicos agem como antioxidantes, não somente por sua habilidade em doar hidrogênio ou elétrons, mas também em virtude de seus radicais intermediários estáveis, que impedem a oxidação de vários ingredientes do alimento, particularmente de lipídios. Carotenóides são constituídos de cadeias de polienos, em um longo sistema de duplas ligações conjugadas, rico em elétrons, responsável pela atividade antioxidante desses compostos: tanto na absorção do oxigênio singlet quanto de radicais livres, para interromper as reações em cadeia onde eles estão envolvidos. Este trabalho teve por finalidade revisar as diferentes formas de avaliação qualitativa e quantitativa dos principais componentes não-nutrientes antioxidantes em alimentos de origem vegetal: compostos fenólicos e carotenóides.