2,477 research outputs found

    Links of the significant wave height distribution in the Mediterranean sea with the Northern Hemisphere teleconnection patterns

    Get PDF
    This study analyzes the link between the SWH (Significant Wave Height) distribution in the Mediterranean Sea during the second half of the 20th century and the Northern Hemisphere SLP (Sea Level Pressure) teleconnection patterns. <br></br> The SWH distribution is computed using the WAM (WAve Model) forced by the surface wind fields provided by the ERA-40 reanalysis for the period 1958–2001. The time series of mid-latitude teleconnection patterns are downloaded from the NOAA web site. This study shows that several mid-latitude patterns are linked to the SWH field in the Mediterranean, especially in its western part during the cold season: East Atlantic Pattern (EA), Scandinavian Pattern (SCA), North Atlantic Oscillation (NAO), East Atlantic/West Russia Pattern (EA/WR) and East Pacific/ North Pacific Pattern (EP/NP). Though the East Atlantic pattern exerts the largest influence, it is not sufficient to characterize the dominant variability. NAO, though relevant, has an effect smaller than EA and comparable to other patterns. Some link results from possibly spurious structures. Patterns which have a very different global structure are associated to similar spatial features of the wave variability in the Mediterranean Sea. These two problems are, admittedly, shortcomings of this analysis, which shows the complexity of the response of the Mediterranean SWH to global scale SLP teleconnection patterns

    Links of the significant wave height distribution in the Mediterranean sea with the Northern Hemisphere teleconnection patterns

    Get PDF
    Abstract. This study analyzes the link between the SWH (Significant Wave Height) distribution in the Mediterranean Sea during the second half of the 20th century and the Northern Hemisphere SLP (Sea Level Pressure) teleconnection patterns. The SWH distribution is computed using the WAM (WAve Model) forced by the surface wind fields provided by the ERA-40 reanalysis for the period 1958&amp;ndash;2001. The time series of mid-latitude teleconnection patterns are downloaded from the NOAA web site. This study shows that several mid-latitude patterns are linked to the SWH field in the Mediterranean, especially in its western part during the cold season: East Atlantic Pattern (EA), Scandinavian Pattern (SCA), North Atlantic Oscillation (NAO), East Atlantic/West Russia Pattern (EA/WR) and East Pacific/ North Pacific Pattern (EP/NP). Though the East Atlantic pattern exerts the largest influence, it is not sufficient to characterize the dominant variability. NAO, though relevant, has an effect smaller than EA and comparable to other patterns. Some link results from possibly spurious structures. Patterns which have a very different global structure are associated to similar spatial features of the wave variability in the Mediterranean Sea. These two problems are, admittedly, shortcomings of this analysis, which shows the complexity of the response of the Mediterranean SWH to global scale SLP teleconnection patterns.</p

    Pollen, Tapetum, and Orbicule Development in Colletia paradoxa

    Get PDF
    Tapetum, orbicule, and pollen grain ontogeny in Colletia paradoxa and Discaria americana were studied with transmission electron microscopy (TEM). The ultrastructural changes observed during the different stages of development in the tapetal cells and related to orbicule and pollen grain formation are described. The proorbicules have the appearance of lipid globule, and their formation is related to the endoplasmic reticulum of rough type (ERr). This is the first report on the presence of orbicules in the family Rhamnaceae. Pollen grains are shed at the bicellular stage

    Kinetics of growth of Leishmania (Leishmania) chagasi cycle in McCoy cell culture

    Get PDF
    Cinéticas de crescimento de Leishmania realizadas in vitro após a internalização da forma promastigota na célula e a ocorrência da transformação do parasito na forma amastigota foram descritas por vários autores, seja com a utilização de explantes de macrófagos em células de baço de hamster ou atualmente da célula de linhagem de macrófago humano U937. Aliando a microscopia à descrição das inter-relações morfológicas e à síntese de moléculas específicas foi possível esclarecer pontos sobre a biologia do parasito. O presente estudo mostra o acompanhamento do ciclo de crescimento da Leishmania chagasi em uma cinética realizada com células de linhagem McCoy, no período de 144 horas. Durante o processo, as transformações morfológicas foram reveladas pela reação de imunofluorescência indireta (RIFI) e as moléculas liberadas no meio extracelular foram observadas pelo método de SDS-PAGE, em intervalos de 24 horas no período de 144 horas. Observou-se que nas primeiras 72 horas, a forma promastigota da L. chagasi fica aderida à membrana das células com aspecto arredondado (amastigota-like). Em 96 horas as células infectadas apresentaram alterações morfológicas; em 120 horas, as células liberaram, para o meio extracelular, antígenos fluorescentes solúveis; e em 144 horas foram observadas novas formas alongadas dos parasitos como se fossem promastigotas. No SDS-PAGE, proteínas com pesos moleculares específicos são observadas em cada ponto da cinética, mostrando que a célula McCoy parece mimetizar o macrófago e que pode ser um modelo útil para o estudo da infecção do binômio leishmânia/célula.The kinetics of growth of Leishmania performed in vitro after internalization of the promastigote form in the cell and the occurrence of the transformation of the parasite into the amastigote form have been described by several authors. They used explants of macrophages in hamster spleen cell culture or in a human macrophage lineage cell, the U937. Using microscopy, the description of morphologic inter-relationship and the analysis of the production of specific molecules, it has been possible to define some of the peculiarities of the biology of the parasite. The present study shows the growth cycle of Leishmania chagasi during the observation of kinetic analysis undertaken with a McCoy cell lineage that lasted for a period of 144 hours. During the process, the morphologic transformation was revealed by indirect immunofluorescence (IF) and the molecules liberated in the extra cellular medium were observed by SDS-PAGE at 24-hour intervals during the whole 144-hour period. It was observed that in the first 72 hours the promastigote form of L. chagasi adhered to the cell membranes and assumed a rounded (amastigote-like) form. At 96 hours the infected cells showed morphologic alterations; at 120 hours the cells had liberated soluble fluorescent antigens into the extra cellular medium. At 144 hours, new elongated forms of the parasites, similar to promastigotes, were observed. In the SDS-PAGE, specific molecular weight proteins were observed at each point of the kinetic analysis showing that the McCoy cell imitates the macrophage and may be considered a useful model for the study of the infection of the Leishmania/cell binomial

    Statistical trend analysis and extreme distribution of significant wave height from 1958 to 1999 – an application to the Italian Seas

    Get PDF
    The study is a statistical analysis of sea states timeseries derived using the wave model WAM forced by the ERA-40 dataset in selected areas near the Italian coasts. For the period 1 January 1958 to 31 December 1999 the analysis yields: (i) the existence of a negative trend in the annual- and winter-averaged sea state heights; (ii) the existence of a turning-point in late 80's in the annual-averaged trend of sea state heights at a site in the Northern Adriatic Sea; (iii) the overall absence of a significant trend in the annual-averaged mean durations of sea states over thresholds; (iv) the assessment of the extreme values on a time-scale of thousand years. The analysis uses two methods to obtain samples of extremes from the independent sea states: the &lt;i&gt;r-largest annual maxima&lt;/i&gt; and the &lt;i&gt;peak-over-threshold&lt;/i&gt;. The two methods show statistical differences in retrieving the return values and more generally in describing the significant wave field. The &lt;i&gt;r-largest annual maxima&lt;/i&gt; method provides more reliable predictions of the extreme values especially for small return periods (&amp;lt;100 years). Finally, the study statistically proves the existence of decadal negative trends in the significant wave heights and by this it conveys useful information on the wave climatology of the Italian seas during the second half of the 20th century

    Diversidad de orbículas en poaceae

    Get PDF
    87-96Anthers of ten species of Poaceae from the province of Buenos Aires (Argentina) were investigated with scanning and transmission electron microscopes. The orbicules can be defined as corpuscles of variable size that show the same electron-density, reaction to the dyes, autofluorescence and resistance to acetolysis as pollen exine does. The orbicules are randomly dispersed on the inner anther locule and they are often attached to a tapetal membrane. In this study, four different types and four subtypes of orbicules were identified. We conclude that the different orbicules types described in this work are representative of the studied tribes, and we suggest that the orbicules morphology may be a useful character in systematic studies

    Inhibitory Activity of Leaves Extracts of Citrullus colocynthis Schrad. on HT29 Human Colon Cancer Cells

    Get PDF
    Aims: Citrullus colocynthis is a plant endemic in Asia, Africa and in the Mediterranean basin. It is used in folk medicine against infections, inflammations and cardiovascular and immune-related diseases. There are further evidences of the use of Citrullus colocynthis Schrad in the treatment of cancer in traditional practices. The present study aimed to determine the potential antiproliferative effects of different Citrullus colocynthis leaf extracts on human cancer cells. Methodology: Antiproliferative and antioxidant effects on HT-29 human colon cancer cells were detected by MTS assay and a modified protocol of the alkaline Comet assay. In vitro antioxidant activities of different leaf extracts were evaluated through DPPH, \u3b2-carotene/linoleic acid and reducing power assays. Results: The leaf chloroform extract exhibited the higher cell growth inhibitory activity without induction of DNA damage; it showed to be able to significantly decrease DNA damage induced by H2O2 (100 M). This antioxidant activity seems to be comparable to that of vitamin C (1 mM). Ethyl acetate, acetone and methanol leaf extracts showed to be the most effective in reducing the stable free DPPH radical (IC50 =113 g/ml), in transforming the Fe3+ to Fe2+ (IC50 = 134 \ub5g/ml) and in inducing linoleic acid oxidation with an inhibition of 31.9 %. Conclusion: Our results confirm the antiproliferative potential of Citrullus colocynthis Schrad. on human cancer cells

    Flebotomíneos de várzea do rio Aguapeí, região noroeste do Estado de São Paulo, Brasil

    Get PDF
    OBJETIVO: Investigar a sazonalidade de flebotomíneos de acordo com sua ocorrência e densidade. MÉTODOS: A pesquisa for realizada em área de várzea do rio Aguapeí, do município de Mirandópolis, Estado de São Paulo. Os flebotomíneos foram capturados mensalmente com armadilhas automáticas luminosas, instaladas das 18:00 às 7:00 horas, durante um ano (2004-2005), em dois locais: varanda de um rancho de pesca e mata. Utilizou-se a média de Williams para o cálculo da sazonalidade dos flebotomíneos e teste de qui-quadrado para comparação. RESULTADOS: Foram capturados 35.995 flebotomíneos. Cinco espécimes eram Brumptomyia avellari, um Psathyromyia (Xiphomyia) hermanlenti e os demais Nyssomyia neivai, que apresentou freqüência mais elevada no inverno. É o primeiro registro de Ps. hermanlenti no Estado. CONCLUSÕES: A alta densidade de Nyssomyia neivai, um dos vetores suspeitos de transmitir a leishmaniose tegumentar americana, aponta o risco de transmissão dessa doença no local, principalmente nos períodos mais secos do ano.OBJECTIVE: To investigate the seasonal variation of sand flies regarding their occurrences and densities. METHODS: The study was conducted in the Aguapeí river floodplain in the state of São Paulo, southeastern Brazil. Sand flies were monthly captured with automatic light traps set up between 18:00 and 7:00 hours, over a period of one year (2004-2005), at two sites: veranda of a domicile and in a forest on the banks of Aguapeí River. The Williams' average was used for estimating the seasonal variation and the Chi-square test for comparison. RESULTS: A total of 35,995 specimens were captured: five Brumptomyia avellari, one Psathyromyia (Xiphomyia) hermanlenti and the rest Nyssomyia neivai, which had the highest frequency during the winter. Ps. hermanlenti is first recorded in state of São Paulo. CONCLUSIONS: The high density of Nyssomyia neivai, a suspected vector of cutaneous leishmaniasis, points out to the risk of transmission of this disease in this setting, especially during drier periods of the year
    corecore