974 resultados para Helmes-Hayes, Rick: The Vertical mosaic revisited


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Connectivity between the terrestrial and marine environment in the Artic is changing as a result of climate change, influencing both freshwater budgets and the supply of carbon to the sea. This study characterizes the optical properties of dissolved organic matter (DOM) within the Lena Delta region and evaluates the behavior of DOM across the fresh water-marine gradient. Six fluorescent components (four humic-like; one marine humic-like; one protein-like) were identified by Parallel Factor Analysis (PARAFAC) with a clear dominance of allochthonous humic-like signals. Colored DOM (CDOM) and dissolved organic carbon (DOC) were highly correlated and had their distribution coupled with hydrographical conditions. Higher DOM concentration and degree of humification were associated with the low salinity waters of the Lena River. Values decreased towards the higher salinity Laptev Sea shelf waters. Results demonstrate different responses of DOM mixing in relation to the vertical structure of the water column, as reflecting the hydrographical dynamics in the region. Two mixing curves for DOM were apparent. In surface waters above the pycnocline there was a sharper decrease in DOM concentration in relation to salinity indicating removal. In the bottom water layer the DOM decrease within salinity was less. We propose there is a removal of DOM occurring primarily at the surface layer, which is likely driven by photodegradation and flocculation.

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The HCMR_SES_LAGRANGIAN_GR2_ MICROBIAL PARAMETERS dataset is based on samples collected in the framework of the project SESAME, in the North Aegean Sea during October 2008. The objectives were to measure the standing stocks and calculate the production of the microbial compartment of the food web, describe the vertical distribution pattern and characterize its structure and function through the water column as influenced by the BSW. Bacterial production was estimated by the 3H-leucine method (Kirchman et al. 1986, Kirchman 1993). At each depth, duplicate samples and a control were incubated with 20 nM L-[4,5 3H]-leucine. Samples were incubated in the dark, at in situ temperature.

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The dataset is based on samples collected in the framework of the project SESAME, in the Ionian, Libyan and Aegean Sea during March- April 2008. The objectives were to measure the standing stocks and calculate the production of the microbial compartment of the food web, describe the vertical distribution pattern and characterize its structure and function through the water column. Heterotrophic bacteria, Synechococcus, Prochlorococcus and Virus abundance: Subsamples for virus, heterotrophic bacteria and cyanobacteria (Synechococcus spp. and Prochlorococcus spp.) counting were analyzed using a FACSCalibur (Becton Dickinson) flow cytometer equipped with a standard laser (488 nm) and filter set and using deionized water as sheath fluid. Fluorescent beads with a diameter of 0.97 µm (Polysciences) were added to each sample as an internal standard, and all parameters were normalized to the beads and expressed as relative units. SYBRGreen I stain (Molecular Probe) was used to stain viral and heterotrophic bacterial DNA. Viruses were counted according to (Brussaard 1984). In order to avoid bulk consentrations of viruses samples we dilluted to Tris-EDTA (pH=8,0) buffer to a final sollution of 1/5 to 1/100. Total abundance and nucleid content classes were calculated using the Paint-A-Gate software (Becton Dickinson).

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The dataset is based on samples collected in the framework of the project SESAME, in the Ionian, Libyan and Aegean Sea during March- April 2008. The objectives were to measure the standing stocks and calculate the production of the microbial compartment of the food web, describe the vertical distribution pattern and characterize its structure and function through the water column. Bacterial production was estimated by the 3H-leucine method (Kirchman et al. 1986, Kirchman 1993). At each depth, duplicate samples and a control were incubated with 20 nM L-[4,5 3H]-leucine. Samples were incubated in the dark, at in situ temperature.

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Sediments from the western and southern part of the Arabian Sea were collected periodically in the spring intermonsoon between March and May 1997 and additionally at the end of the Northeast Monsoon in February 1998. Assemblages of Rose Bengal stained, living deep-sea benthic foraminifera, their densities, vertical distribution pattern, and diversity were analysed after the Northeast Monsoon and short-time changes were recorded. In the western Arabian Sea, foraminiferal numbers increased steadily between March and the beginning of May, especially in the smaller size classes (30-63 µm, 63-125 µm). At the same time, the deepening of the foraminiferal living horizon, variable diversity and rapid variations between dominant foraminiferal communities were observed. We interpret these observations as the time-dependent response of benthic foraminifera to enhanced organic carbon fluxes during and after the Northeast Monsoon. In the southern Arabian Sea, constant low foraminiferal abundances during time, no distinctive change in the vertical distribution, reduced diversity, and more stable foraminiferal communities were noticed, which indicates no or little influence of the Northeast Monsoon to benthic foraminifera in this region.

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Five holes were drilled at two sites in the Sea of Japan during Ocean Drilling Program (ODP) Leg 128. Site 798 is located on Oki Ridge at a depth of about 900 m. Sediment age at Site 798 ranges from Pliocene to Holocene. Site 799 is located in the Kita-Yamato Trough at depth of 2000 m and below the present calcite compensation depth (CCD); the sediment ranges from Miocene to Holocene in age. Samples from all holes contain benthic foraminifers. Faunal evidence of downslope displacement is frequent in Holes 799A and 799B. The vertical frequency distribution of some dominant species shows that significant faunal changes occur in Holes 798A-C on Oki Ridge. Based on the faunal change and the thickness of sediments, it appears that the Oki Ridge was uplifted more than 1,000 m during last 4 m.y. Benthic foraminifers also demonstrate that the water depth of Site 799 rapidly changed from upper bathyal to lower bathyal during middle Miocene time. The appearance of benthic foraminifer species common to anaerobic environments suggests that the dysaerobic to anaerobic bottom conditions existed during the evolution of the Sea of Japan. Faunal distributions also suggest that the 'Tertiary-type' species recognized in the Neogene strata of the Japan Sea coastal regions disappeared sequentially from the Sea of Japan during Pliocene to late Pleistocene.

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En el presente artículo se describen los factores que provocaron Ias rivalidades y tensiones internas en el Peronismo Mendocino, lo que causó la caída del gobierno de Alberto Martínez Baca - Carlos Mendoza. En este proceso se interrelacionan diferentes actores: la ofensiva extrapartidaria, el movimiento obrero, los jóvenes revolucionarios, los políticos verticalistas, etc. Para ello se comienza presentando el mosaico partidario mendocino en el proceso que desemboca en la transición democrática de 1973. Básicamente, se pone de manifiesto, la interacción entre el Partido Demócrata y el régimen militar, el sesgo moderado de la UCR local, y la conflictiva heterogeneidad del peronismo. Con grandes dificultades para solucionar sus diferencias a través de canales institucionales, pero al mismo tiempo con una dinámica de intensa politización. Por eso, se plantean algunas observaciones sobre las características de la radicalización juvenil, y, se ofrece una breve reconstrucción historiográfica del movimiento obrero mendocino desde una perspectiva de análisis que tiene en cuenta centralmente, dos aspectos: su relación con el liderazgo carismático de Perón, y su relación -ambivalente- con los gobiernos de la "Revolución Argentina". La búsqueda de la desperonización del país, la puja por tratar de captar los votos otrora peronistas, las ansias individuales al abrirse eI mercado eIectoral, la división de posiciones u opiniones frente a Ios gobiernos autoritarios, y la radicalización social, trajo aparejado una profundización de la crisis interna. Crisis que se vio reflejada en el proceso que condujo a la elección de Alberto Martínez Baca y Carlos Mendoza como candidatos a la gobernación, poniendo de manifiesto la influencia de los sectores identificados con el "peronismo revolucionario" y la ofensiva de la "derecha peronista". Su corolario: la intervención a los tres poderes de la provincia.

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El artículo examina una dimensión vertical de la historia diferente del desarrollo horizontal de los sucesos. Primero, analiza el trasfondo ofrecido por los fundadores de la fenomenología. E. Husserl, M. Scheler y M. Heidegger se refieren de diversas maneras a un desarrollo recíproco de Dios y hombre. Luego, se ocupa de la noción de la naturaleza como matriz de la historia según M. Merleau-Ponty. En tercer lugar, la atención recae en la concepción de E. Levinas sobre una cultura ética, que, sin comienzo histórico, se encuentra más allá de las culturas del saber y del arte. El cuarto apartado considera las raíces de la historia en el “yo puedo" individual tal como se funda, según M. Henry, en la Vida Absoluta. El apartado final del artículo se refiere a un reino inmemorial vinculado a la dimensión vertical y desarrollado en las tres esferas de la naturaleza, la intersubjetividad y la interioridad.

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We use a multiproxy approach to monitor changes in the vertical profile of the Indonesian Throughflow as well as monsoonal wind and precipitation patterns in the Timor Sea on glacial-interglacial, precessional, and suborbital timescales. We focus on an interval of extreme climate change and sea level variation: marine isotope (MIS) 6 to MIS 5e. Paleoproductivity fluctuations in the Timor Sea follow a precessional beat related to the intensity of the Australian (NW) monsoon. Paired Mg/Ca and d18O measurements of surface- and thermocline-dwelling planktonic foraminifers (G. ruber and P. obliquiloculata) indicate an increase of >4°C in both surface and thermocline water temperatures during Termination II. Tropical sea surface temperature changed synchronously with ice volume (benthic d18O) during deglaciation, implying a direct coupling of high- and low-latitude climate via atmospheric and/or upper ocean circulation. Substantial cooling and freshening of thermocline waters occurred toward the end of Termination II and during MIS 5e, indicating a change in the vertical profile of the Indonesian Throughflow from surface- to thermocline-dominated flow.

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We measured oxygen isotopes and Mg/Ca ratios in the surface-dwelling planktonic foraminifer Globigerinoides ruber (white s.s.) and the thermocline dweller Pulleniatina obliquiloculata to investigate upper ocean spatial variability in the Indo-Pacific Warm Pool (IPWP). We focused on three critical time intervals: the Last Glacial Maximum (LGM; 18-21.5 ka), the early Holocene (8-9 ka), and the late Holocene (0-2 ka). Our records from 24 stations in the South China Sea, Timor Sea, Indonesian seas, and western Pacific indicate overall dry and cool conditions in the IPWP during the LGM with a low thermal gradient between surface and thermocline waters. During the early Holocene, sea surface temperatures increased by ~3°C over the entire region, indicating intensification of the IPWP. However, in the eastern Indian Ocean (Timor Sea), the thermocline gradually shoaled from the LGM to early Holocene, reflecting intensification of the subsurface Indonesian Throughflow (ITF). Increased surface salinity in the South China Sea during the Holocene appears related to northward displacement of the monsoonal rain belt over the Asian continent together with enhanced influx of saltier Pacific surface water through the Luzon Strait and freshwater export through the Java Sea. Opening of the freshwater portal through the Java Sea in the early Holocene led to a change in the vertical structure of the ITF from surface- to thermocline-dominated flow and to substantial freshening of Timor Sea thermocline waters.

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Based on samples with a 140-liter bottles in the upwelling region of the equatorial Pacific, an analysis was made of vertical distribution of various members of the plankton community of organisms (small and large phytoplankton, bacteria, different groups of protozoans, small and large, mainly herbivorous and predatory, animals). There is a distinct vertical divergence between layers of dominance of groups with similar feeding habits against the background of uneven quantitative distribution. Contrariwise, there are masses of consumers in the layers of high concentration of their potential prey.

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46 hydropolyp species of 28 genera and 10 families were sampled during the "Meteor" passage 1964/65 (IIOE) through the Red Sea and its northern and southern exits and on the occasion of several ecological investigations of 29 selected coral reef sections of the central Red Sea and the Gulf of Aqaba. These collections comprise 128 single records of hydropolyp species. Three species and two genera each with one species are doubtful. 25 species, seven genera, one family and one subfamily, together from 49 records have not previously been found in the Red Sea and its exits. Including these newly reported species, the total list increases from 64 species and 112 records to 89 species and 240 single records and 51 additional ones. Scanning microscopical photos, made for the first time for the illustration of the hydropolyps, have been shown to be suitable for a better characterization and diagnosis of the species. Qualified results on the reasons for the horizontal distribution of the species known from the Red Sea area cannot be given because of the low number of samples sporadically distributed through the whole area. In contrast with this fact, the vertical spread of the species sampled seems primarily to be regulated by water exchange and light intensity. For example, four species of hydropolyps are excellent indicators of certain abiotic factors or combinations of them: Gymnangium eximium reacts extremely stenophote-photophobe-rheophil, Eudendrium ramosum moderately stenophote-photophobe-rheophobe, Lytocarpus philippinus moderately stenophote-photophil-rheophil, and Halocordyle disticha var. australis extremely stenophote-photophil but moderately rheophil. Other species have been found throughout all the light zones. Combined with the small size of their colonies their euryphotic behaviour does not allow their use as indicator species.

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Metamorphic rocks of the Khavyven Highland in eastern Kamchatka were determined to comprise two complexes of metavolcanic rocks that have different ages and are associated with subordinate amounts of metasediments. The complex composing the lower part of the visible vertical section of the highland is dominated by leucocratic amphibole-mica (+/-garnet) and epidote-mica (+/-garnet) crystalline schists, whose protoliths were andesites and dacites and their high-K varieties of island-arc calc-alkaline series. The other complex composing the upper part of the vertical section consists of spilitized basaltoids transformed into epidote-amphibole and phengite-epidote-amphibole green schists, which form (together with quartzites, serpentinized peridotites, serpentinites, and gabbroids) a sea-margin ophiolitic association. High LILE concentrations, high K/La, Ba/Th, Th/Ta, and La/Nb ratios, deep Ta-Nb minima, and low (La/Yb)_N and high 87Sr/86Sr ratios of the crystalline schists of the lower unit are demonstrated to testify to their subduction nature and suggest that their protolithic volcanics were produced in the suprasubduction environment of the Ozernoi-Valaginskii (Achaivayam-Valaginskii) island volcanic arc of Campanian-Paleogene age. The green schists of the upper unit show features of depleted MOR tholeiitic melts and subduction melts, which cause the deep Ta-Nb minima, and low K/La and 87Sr/86Sr ratios suggesting that the green schists formed in a marginal basin in front of the Ozernoi-Valaginskaya island arc. Recently obtained K-Ar ages in the Khavyven Highland vary from 32.4 to 39.3 Ma and indicate that metamorphism of the protolithic rocks occurred in Eocene under effect of collision and accretion processes of the arc complexes of the Ozernoi-Valaginskii and Kronotskii island arcs with the Asian continent and the closure of forearc oceanic basins in front of them. The modern position of the collision suture that marks the fossil subduction zone of the Ozernoi-Valaginskii arc and is spatially restricted to the buried Khavyven uplift in the Central Kamchatka Depression characterized by well-pronounced linear gravity anomalies.

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Concentrations of total organic carbon (TOC) were determined on samples collected during six cruises in the northern Arabian Sea during the 1995 US JGOFS Arabian Sea Process Study. Total organic carbon concentrations and integrated stocks in the upper ocean varied both spatially and seasonally. Highest mixed-layer TOC concentrations (80-100 µM C) were observed near the coast when upwelling was not active, while upwelling tended to reduce local concentrations. In the open ocean, highest mixed-layer TOC concentrations (80-95 µM C) developed in winter (period of the NE Monsoon) and remained through mid summer (early to mid-SW Monsoon). Lowest open ocean mixed-layer concentrations (65-75 µM C) occurred late in the summer (late SW Monsoon) and during the Fall Intermonsoon period. The changes in TOC concentrations resulted in seasonal variations in mean TOC stocks (upper 150 m) of 1.5-2 mole C/m**2, with the lowest stocks found late in the summer during the SW Monsoon-Fall Intermonsoon transition. The seasonal accumulation of TOC north of 15°N was 31-41 x 10**12 g C, mostly taking place over the period of the NE Monsoon, and equivalent to 6-8% of annual primary production estimated for that region in the mid-1970s. A net TOC production rate of 12 mmole C/m**2/d over the period of the NE Monsoon represented ~80% of net community production. Net TOC production was nil during the SW Monsoon, so vertical export would have dominated the export terms over that period. Total organic carbon concentrations varied in vertical profiles with the vertical layering of the water masses, with the Persian Gulf Water TOC concentrations showing a clear signal. Deep water (>2000 m) TOC concentrations were uniform across the basin and over the period of the cruises, averaging 42.3±1.4 µM C.