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Sample records for early archean seafloor-hydrothermal

  1. Metamorphic fluid flow in the northeastern part of the 3.8-3.7 Ga Isua Greenstone Belt (SW Greenland): A re-evalution of fluid inclusion evidence for early Archean seafloor-hydrothermal systems

    DEFF Research Database (Denmark)

    Heijlen, Wouter; Appel, P. W. U.; Frezzotti, M. L.

    2006-01-01

    . In most quartz crystals, however, recrystallization obliterated such early fluid inclusion assemblages and left graphite and carbonate as solid inclusions in recrystallized grains. Intragranular fluid inclusion trails in the recrystallized grains of breccia cementing and crosscutting quartz veins have CO2...... density (ranging from 48.0 to > 105.3 cm(3)/Mol) and metastable H2O NaCl(-other salt?) brines (similar to 28 eq. wt% NaCl). Finally, the youngest fluid inclusion assemblages are found in non-luminescent secondary quartz and contain low-density CH4 (molar volume > 105.33 cm(3)/Mol) and low-salinity H2O.......5-2 kbar. The quartz globules in the pillow fragments only contain sporadic CH4(+H-2) and brine inclusions, corresponding with the late generations present in the cementing and crosscutting veins. We argue that due to the large extent of static recrystallization in quartz globules in the pillow breccia...

  2. Non-traditional Stable Isotope Systematics of Seafloor Hydrothermal Systems

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    Rouxel, O. J.

    2009-05-01

    Seafloor hydrothermal activity at mid-ocean ridges is one of the fundamental processes controlling the chemistry of the oceans and the altered oceanic crust. Past studies have demonstrated the complexity and diversity of seafloor hydrothermal systems and have highlighted the importance of subsurface environments in controlling the composition of hydrothermal fluids and mineralization types. Traditionally, the behavior of metals in seafloor hydrothermal systems have been investigated by integrating results from laboratory studies, theoretical models, mineralogy and fluid and mineral chemistry. Isotope ratios of various metals and metalloids, such as Fe, Cu, Zn, Se, Cd and Sb have recently provided new approaches for the study of seafloor hydrothermal systems. Despite these initial investigations, the cause of the isotopic variability of these elements remains poorly constrained. We have little understanding of the isotope variations between vent types (black or white smokers) as well as the influence of source rock composition (basalt, felsic or ultrabasic rocks) and alteration types. Here, I will review and present new results of metal isotope systematics of seafloor hydrothermal systems, in particular: (1) determination of empirical isotope fractionation factors for Zn, Fe and Cu-isotopes through isotopic analysis of mono-mineralic sulfide grains lining the internal chimney wall in contact with hydrothermal fluid; (2) comparison of Fe- and Cu-isotope signatures of vent fluids from mid- oceanic and back-arc hydrothermal fields, spanning wide ranges of pH, temperature, metal concentrations and contributions of magmatic fluids enriched in SO2. Ultimately, the use of complementary non-traditional stable isotope systems may help identify and constrain the complex interactions between fluids,minerals, and organisms in seafloor hydrothermal systems.

  3. On the photosynthetic potential in the very Early Archean oceans.

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    Avila, Daile; Cardenas, Rolando; Martin, Osmel

    2013-02-01

    In this work we apply a mathematical model of photosynthesis to quantify the potential for photosynthetic life in the very Early Archean oceans. We assume the presence of oceanic blockers of ultraviolet radiation, specifically ferrous ions. For this scenario, our results suggest a potential for photosynthetic life greater than or similar to that in later eras/eons, such as the Late Archean and the current Phanerozoic eon.

  4. Reconciling atmospheric temperatures in the early Archean

    DEFF Research Database (Denmark)

    Pope, Emily Catherine; Bird, Dennis K.; Rosing, Minik Thorleif

    rock record. The goal of this study is to compile and reconcile Archean geologic and geochemical features that are in some way controlled by surface temperature and/or atmospheric composition, so that at the very least paleoclimate models can be checked by physical limits. Data used to this end include...... weathering on climate). Selective alteration of δD in Isua rocks to values of -130 to -100‰ post-dates ca. 3.55Ga Ameralik dikes, but may be associated with a poorly defined 2.6-2.8Ga metamorphic event that is coincident with the amalgamation of the “Kenorland supercontinent.”...

  5. Archean komatiite volcanism controlled by the evolution of early continents.

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    Mole, David R; Fiorentini, Marco L; Thebaud, Nicolas; Cassidy, Kevin F; McCuaig, T Campbell; Kirkland, Christopher L; Romano, Sandra S; Doublier, Michael P; Belousova, Elena A; Barnes, Stephen J; Miller, John

    2014-07-15

    The generation and evolution of Earth's continental crust has played a fundamental role in the development of the planet. Its formation modified the composition of the mantle, contributed to the establishment of the atmosphere, and led to the creation of ecological niches important for early life. Here we show that in the Archean, the formation and stabilization of continents also controlled the location, geochemistry, and volcanology of the hottest preserved lavas on Earth: komatiites. These magmas typically represent 50-30% partial melting of the mantle and subsequently record important information on the thermal and chemical evolution of the Archean-Proterozoic Earth. As a result, it is vital to constrain and understand the processes that govern their localization and emplacement. Here, we combined Lu-Hf isotopes and U-Pb geochronology to map the four-dimensional evolution of the Yilgarn Craton, Western Australia, and reveal the progressive development of an Archean microcontinent. Our results show that in the early Earth, relatively small crustal blocks, analogous to modern microplates, progressively amalgamated to form larger continental masses, and eventually the first cratons. This cratonization process drove the hottest and most voluminous komatiite eruptions to the edge of established continental blocks. The dynamic evolution of the early continents thus directly influenced the addition of deep mantle material to the Archean crust, oceans, and atmosphere, while also providing a fundamental control on the distribution of major magmatic ore deposits.

  6. Early Archean serpentine mud volcanoes at Isua, Greenland, as a niche for early life.

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    Pons, Marie-Laure; Quitté, Ghylaine; Fujii, Toshiyuki; Rosing, Minik T; Reynard, Bruno; Moynier, Frederic; Douchet, Chantal; Albarède, Francis

    2011-10-25

    The Isua Supracrustal Belt, Greenland, of Early Archean age (3.81-3.70 Ga) represents the oldest crustal segment on Earth. Its complex lithology comprises an ophiolite-like unit and volcanic rocks reminiscent of boninites, which tie Isua supracrustals to an island arc environment. We here present zinc (Zn) isotope compositions measured on serpentinites and other rocks from the Isua supracrustal sequence and on serpentinites from modern ophiolites, midocean ridges, and the Mariana forearc. In stark contrast to modern midocean ridge and ophiolite serpentinites, Zn in Isua and Mariana serpentinites is markedly depleted in heavy isotopes with respect to the igneous average. Based on recent results of Zn isotope fractionation between coexisting species in solution, the Isua serpentinites were permeated by carbonate-rich, high-pH hydrothermal solutions at medium temperature (100-300 °C). Zinc isotopes therefore stand out as a pH meter for fossil hydrothermal solutions. The geochemical features of the Isua fluids resemble the interstitial fluids sampled in the mud volcano serpentinites of the Mariana forearc. The reduced character and the high pH inferred for these fluids make Archean serpentine mud volcanoes a particularly favorable setting for the early stabilization of amino acids.

  7. Albedo and heat transport in 3-D model simulations of the early Archean climate

    Directory of Open Access Journals (Sweden)

    H. Kienert

    2013-08-01

    Full Text Available At the beginning of the Archean eon (ca. 3.8 billion years ago, the Earth's climate state was significantly different from today due to the lower solar luminosity, smaller continental fraction, higher rotation rate and, presumably, significantly larger greenhouse gas concentrations. All these aspects play a role in solutions to the "faint young Sun paradox" which must explain why the ocean surface was not fully frozen at that time. Here, we present 3-D model simulations of climate states that are consistent with early Archean boundary conditions and have different CO2 concentrations, aiming at an understanding of the fundamental characteristics of the early Archean climate system. In order to do so, we have appropriately modified an intermediate complexity climate model that couples a statistical-dynamical atmosphere model (involving parameterizations of the dynamics to an ocean general circulation model and a thermodynamic-dynamic sea-ice model. We focus on three states: one of them is ice-free, one has the same mean surface air temperature of 288 K as today's Earth and the third one is the coldest stable state in which there is still an area with liquid surface water (i.e. the critical state at the transition to a "snowball Earth". We find a reduction in meridional heat transport compared to today, which leads to a steeper latitudinal temperature profile and has atmospheric as well as oceanic contributions. Ocean surface velocities are largely zonal, and the strength of the atmospheric meridional circulation is significantly reduced in all three states. These aspects contribute to the observed relation between global mean temperature and albedo, which we suggest as a parameterization of the ice-albedo feedback for 1-D model simulations of the early Archean and thus the faint young Sun problem.

  8. Mercury Anomaly in the Okinawa Trough Sediments—An Indicator of Modern Seafloor Hydrothermal Activity

    Institute of Scientific and Technical Information of China (English)

    赵一阳; 鄢明才

    1995-01-01

    The Okinawa Trough is located between the shelf-sea area of the East China Sea and the deep-sea area of western Pacific Ocean.More than 60 chemical elements in the sediments from the shelf area of the East China Sea,the Okinawa Trough and western Pacific Ocean were determined by advanced techniques including neutron acti-vation analysis,X-ray fluorescence spectrometry,atomic fluorescence spectrometry and atomic absorption spectrometry.Quantitative comparisons of the element abundances of the sediments were made in terms of the enrichment coefficients(K) of the elements.K>1.5 indicates enrichment (K=1.5-2, weak enrichment;K=2-4,strong enrichment) and K>4,anomalous enrichment.The results show that the Okinawa Trough sediments are characterized by Hg anomaly and the enrichment of such elements as Au,Ag,Se,Te,Sb,Cd,Mn,Mo,etc.Detailed studies show that the excess Hg comes from hydrothermal solutions rather than from the continent,sea water ,marine organisms,cosmic dust or vol-canic rocks.Attributed to modern hydrothermal activities on the sea floor ,Hg anomaly can be used as a geochemical indicator of modern seafloor hydrothermal activity.

  9. Key factors influencing rates of heterotrophic sulfate reduction in active seafloor hydrothermal massive sulfide deposits

    Directory of Open Access Journals (Sweden)

    Kiana Laieikawai Frank

    2015-12-01

    Full Text Available Hydrothermal vents are thermally and geochemically dynamic habitats, and the organisms therein are subject to steep gradients in temperature and chemistry. To date, the influence of these environmental dynamics on microbial sulfate reduction has not been well constrained. Here, via multivariate experiments, we evaluate the effects of key environmental variables (temperature, pH, H2S, SO42-, DOC on sulfate reduction rates and metabolic energy yields in material recovered from a hydrothermal flange from the Grotto edifice in the Main Endeavor Field, Juan de Fuca Ridge. Sulfate reduction was measured in batch reactions across a range of physico-chemical conditions. Temperature and pH were the strongest stimuli, and maximum sulfate reduction rates were observed at 50 °C and pH 6, suggesting that the in situ community of sulfate-reducing organisms in Grotto flanges may be most active in a slightly acidic and moderate thermal/chemical regime. At pH 4, sulfate reduction rates increased with sulfide concentrations most likely due to the mitigation of metal toxicity. While substrate concentrations also influenced sulfate reduction rates, energy-rich conditions muted the effect of metabolic energetics on sulfate reduction rates. We posit that variability in sulfate reduction rates reflect the response of the active microbial consortia to environmental constraints on in situ microbial physiology, toxicity, and the type and extent of energy limitation. These experiments help to constrain models of the spatial contribution of heterotrophic sulfate reduction within the complex gradients inherent to seafloor hydrothermal deposits.

  10. Petrochronology in constraining early Archean Earth processes and environments: Barberton greenstone belt, South Africa

    Science.gov (United States)

    Grosch, Eugene

    2017-04-01

    Analytical and petrological software developments over the past decade have seen rapid innovation in high-spatial resolution petrological techniques, for example, laser-ablation ICP-MS, secondary ion microprobe (SIMS, nano-SIMS), thermodynamic modelling and electron microprobe microscale mapping techniques (e.g. XMapTools). This presentation will focus on the application of petrochronology to ca. 3.55 to 3.33 billion-year-old metavolcanic and sedimentary rocks of the Onverwacht Group, shedding light on the earliest geologic evolution of the Paleoarchean Barberton greenstone belt (BGB) of South Africa. The field, scientific drilling and petrological research conducted over the past 8 years, aims to illustrate how: (a) LA-ICP-MS and SIMS U-Pb detrital zircon geochronology has helped identify the earliest tectono-sedimentary basin and sediment sources in the BGB, as well as reconstructing geodynamic processes as early as ca. 3.432 billion-years ago; (b) in-situ SIMS multiple sulphur isotope analysis of sulphides across various early Archean rock units help to reconstruct atmospheric, surface and subsurface environments on early Archean Earth and (c) the earliest candidate textural traces for subsurface microbial life can be investigated by in-situ LA-ICP-MS U-Pb dating of titanite, micro-XANES Fe-speciation analysis and metamorphic microscale mapping. Collectively, petrochronology combined with high-resolution field mapping studies, is a powerful multi-disciplinary approach towards deciphering petrogenetic and geodynamic processes preserved in the Paleoarchean Barberton greenstone belt of South Africa, with implications for early Archean Earth evolution.

  11. Evidence for and implications of an Early Archean terrestrial impact record

    International Nuclear Information System (INIS)

    Lowe, D.R.; Byerly, G.R.

    1988-01-01

    Early Archean, 3.5 to 3.2 Ga, greenstone sequences in South Africa and Western Australia contain a well-preserved record of early terrestrial meteorite impacts. The main impact-produced deposits are layers, 10 cm to over 1 m thick, composed largely of sand-sized spherules, 0.1 to 4 mm in diameter. The beds studied to date show an assemblage of features indicating formation by the fall of debris from impact-generated ejecta clouds. Some presented data effectively rule out normal magmatic or sedimentary processes in the origin of these units and provide substantial support for an origin by large impacts on the early earth. The presence of at least four, remarkably thick, nearly pure spherule layers suggests that smaller-scale impact deposits may be even more abundant in these sequences. The existence of a well-preserved Archean terrestrial impact record suggests that a direct source of evidence is available regarding a number of important aspects of early earth history

  12. Extreme Hf and light Fe isotopes in Archean komatiites - a remnant of very early mantle depletion?

    Science.gov (United States)

    Nebel, O.; Sossi, P.; Campbell, I. H.; Van Kranendonk, M. J.

    2014-12-01

    Hafnium isotope signatures in some Archean komatiites (ca. 3.5-3.0 billion years old) require a mantle source with a time-integrated Lu/Hf that exceeds average modern depleted mantle. Investigation of the timing and locus of parent-daughter fractionation in their mantle sources potentially constrains differentiation processes in the early Earth and their subsequent distribution and storage. In addition, they may help to constrain the Hf isotope evolution of the greater depleted mantle. In order to shed light on these processes, we discuss radiogenic Hf isotopes in conjunction with stable Fe isotope systematics in Archean komatiites from the Pilbara craton in Western Australia. Our findings indicate that, after careful evaluation of the effects of alteration, pristine samples are characterised by initial 176Hf/177Hf, which lie above the age-corrected depleted mantle, as a consequence of ancient melt extraction. Iron isotope systematics for these samples further point to a mantle source that is isotopically lighter than average modern depleted mantle, which is also consistent with melt-depletion. Taken together, these observations require a component of an old, super-depleted reservoir in the komatiite mantle source(s) that survived in the mantle for possibly hundreds of millions of years. The Lu/Hf of this refractory mantle appears to be complementary to, and therefore contemporaneous with, the first terrestrial crust, as preserved in Hadean (i.e., > 4 Ga) detrital zircon cores, which may indicate a causal relationship between them. We will discuss implications for very early mantle dynamics and the formation of very early mantle reservoirs.

  13. River Valley pluton, Ontario - A late-Archean/early-Proterozoic anorthositic intrusion in the Grenville Province

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    Ashwal, Lewis D.; Wooden, Joseph L.

    1989-01-01

    This paper presents Nd, Sr, and Pb isotopic data indicating a late-Archean/early-Proterozoic age for the River Valley anorthositic pluton of the southwestern Grenville Province of Sudbury, Ontario. Pb-Pb isotopic data on 10 whole-rock samples ranging in composition from anorthosite to gabbro yield an age of 2560 + or - 155 Ma. The River Valley pluton is thus the oldest anorthositic intrusive yet recognized within the Grenville Province. The Sm-Nd isotopic system records an age of 2377 + or - 68 Ma. High Pb-208/Pb-204 of deformed samples relative to igneous-textured rocks implies Th introduction and/or U loss during metamorphism in the River Valley area. Rb-Sr data from igneous-textured and deformed samples and from mineral separates give an age of 2185 + or - 105 Ma, indicating substantial disturbance of the Rb-Sr isotopic system.

  14. Archean greenstone-tonalite duality: Thermochemical mantle convection models or plate tectonics in the early Earth global dynamics?

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    Kerrich, Robert; Polat, Ali

    2006-03-01

    Mantle convection and plate tectonics are one system, because oceanic plates are cold upper thermal boundary layers of the convection cells. As a corollary, Phanerozoic-style of plate tectonics or more likely a different version of it (i.e. a larger number of slowly moving plates, or similar number of faster plates) is expected to have operated in the hotter, vigorously convecting early Earth. Despite the recent advances in understanding the origin of Archean greenstone-granitoid terranes, the question regarding the operation of plate tectonics in the early Earth remains still controversial. Numerical model outputs for the Archean Earth range from predominantly shallow to flat subduction between 4.0 and 2.5 Ga and well-established steep subduction since 2.5 Ga [Abbott, D., Drury, R., Smith, W.H.F., 1994. Flat to steep transition in subduction style. Geology 22, 937-940], to no plate tectonics but rather foundering of 1000 km sectors of basaltic crust, then "resurfaced" by upper asthenospheric mantle basaltic melts that generate the observed duality of basalts and tonalities [van Thienen, P., van den Berg, A.P., Vlaar, N.J., 2004a. Production and recycling of oceanic crust in the early earth. Tectonophysics 386, 41-65; van Thienen, P., Van den Berg, A.P., Vlaar, N.J., 2004b. On the formation of continental silicic melts in thermochemical mantle convection models: implications for early Earth. Tectonophysics 394, 111-124]. These model outputs can be tested against the geological record. Greenstone belt volcanics are composites of komatiite-basalt plateau sequences erupted from deep mantle plumes and bimodal basalt-dacite sequences having the geochemical signatures of convergent margins; i.e. horizontally imbricated plateau and island arc crust. Greenstone belts from 3.8 to 2.5 Ga include volcanic types reported from Cenozoic convergent margins including: boninites; arc picrites; and the association of adakites-Mg andesites- and Nb-enriched basalts. Archean cratons

  15. Deposition of talc - kerolite-smectite - smectite at seafloor hydrothermal vent fields: Evidence from mineralogical, geochemical and oxygen isotope studies

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    Dekov, V.M.; Cuadros, J.; Shanks, Wayne C.; Koski, R.A.

    2008-01-01

    Talc, kerolite-smectite, smectite, chlorite-smectite and chlorite samples from sediments, chimneys and massive sulfides from six seafloor hydrothermal areas have been analyzed for mineralogy, chemistry and oxygen isotopes. Samples are from both peridotite- and basalt-hosted hydrothermal systems, and basaltic systems include sediment-free and sediment-covered sites. Mg-phyllosilicates at seafloor hydrothermal sites have previously been described as talc, stevensite or saponite. In contrast, new data show tri-octahedral Mg-phyllosilicates ranging from pure talc and Fe-rich talc, through kerolite-rich kerolite-smectite to smectite-rich kerolite-smectite and tri-octahedral smectite. The most common occurrence is mixed-layer kerolite-smectite, which shows an almost complete interstratification series with 5 to 85% smectitic layers. The smectite interstratified with kerolite is mostly tri-octahedral. The degree of crystal perfection of the clay sequence decreases generally from talc to kerolite-smectite with lower crystalline perfection as the proportion of smectite layers in kerolite-smectite increases. Our studies do not support any dependence of the precipitated minerals on the type/subtype of hydrothermal system. Oxygen isotope geothermometry demonstrates that talc and kerolite-smectite precipitated in chimneys, massive sulfide mounds, at the sediment surface and in open cracks in the sediment near seafloor are high-temperature (> 250????C) phases that are most probably the result of focused fluid discharge. The other end-member of this tri-octahedral Mg-phyllosilicate sequence, smectite, is a moderate-temperature (200-250????C) phase forming deep within the sediment (??? 0.8??m). Chlorite and chlorite-smectite, which constitute the alteration sediment matrix around the hydrothermal mounds, are lower-temperature (150-200????C) phases produced by diffuse fluid discharge through the sediment around the hydrothermal conduits. In addition to temperature, other two

  16. Evaluation of early Archean volcaniclastic and volcanic flow rocks as possible sites for carbonaceous fossil microbes.

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    Walsh, Maud M

    2004-01-01

    Sedimentary rocks have traditionally been the focus of the search for Archean microfossils; the Earth's oldest fossil bacteria are associated with carbonaceous matter in sedimentary cherts in greenstone belts in the eastern Pilbara block of Western Australia and Barberton greenstone belt of South Africa. Reports of possible fossils in a martian meteorite composed of igneous rock and the discovery of modern bacteria associated with basalts have stimulated a new look at Archean volcanic rocks as possible sites for fossil microbes. This study examines silicified volcaniclastic rocks, near-surface altered volcanic flow rocks, and associated stromatolite- like structures from the Archean Barberton greenstone belt to evaluate their potential for the preservation of carbonaceous fossils. Detrital carbonaceous particles are widely admixed with current-deposited debris. Carbonaceous matter is also present in altered volcanic flow rocks as sparse particles in silica veins that appear to be fed by overlying carbonaceous chert layers. Neither microfossils nor mat-like material was identified in the altered volcanic rocks or adjacent stromatolite-like structures. Ancient volcanic flow and volcaniclastic rocks are not promising sites for carbonaceous fossil preservation.

  17. Organic compounds in fluid inclusions of Archean quartz-Analogues of prebiotic chemistry on early Earth.

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    Schreiber, Ulrich; Mayer, Christian; Schmitz, Oliver J; Rosendahl, Pia; Bronja, Amela; Greule, Markus; Keppler, Frank; Mulder, Ines; Sattler, Tobias; Schöler, Heinz F

    2017-01-01

    The origin of life is still an unsolved mystery in science. Hypothetically, prebiotic chemistry and the formation of protocells may have evolved in the hydrothermal environment of tectonic fault zones in the upper continental crust, an environment where sensitive molecules are protected against degradation induced e.g. by UV radiation. The composition of fluid inclusions in minerals such as quartz crystals which have grown in this environment during the Archean period might provide important information about the first organic molecules formed by hydrothermal synthesis. Here we present evidence for organic compounds which were preserved in fluid inclusions of Archean quartz minerals from Western Australia. We found a variety of organic compounds such as alkanes, halocarbons, alcohols and aldehydes which unambiguously show that simple and even more complex prebiotic organic molecules have been formed by hydrothermal processes. Stable-isotope analysis confirms that the methane found in the inclusions has most likely been formed from abiotic sources by hydrothermal chemistry. Obviously, the liquid phase in the continental Archean crust provided an interesting choice of functional organic molecules. We conclude that organic substances such as these could have made an important contribution to prebiotic chemistry which might eventually have led to the formation of living cells.

  18. Sulfur Isotope Trends in Archean Microbialite Facies Record Early Oxygen Production and Consumption

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    Zerkle, A.; Meyer, N.; Izon, G.; Poulton, S.; Farquhar, J.; Claire, M.

    2014-12-01

    The major and minor sulfur isotope composition (δ34S and Δ33S) of pyrites preserved in ~2.65-2.5 billion-year-old (Ga) microbialites record localized oxygen production and consumption near the mat surface. These trends are preserved in two separate drill cores (GKF01 and BH1-Sacha) transecting the Campbellrand-Malmani carbonate platform (Ghaap Group, Transvaal Supergroup, South Africa; Zerkle et al., 2012; Izon et al., in review). Microbialite pyrites possess positive Δ33S values, plotting parallel to typical Archean trends (with a Δ33S/δ34S slope of ~0.9) but enriched in 34S by ~3 to 7‰. We propose that these 34S-enriched pyrites were formed from a residual pool of sulfide that was partially oxidized via molecular oxygen produced by surface mat-dwelling cyanobacteria. Sulfide, carrying the range of Archean Δ33S values, could have been produced deeper within the microbial mat by the reduction of sulfate and elemental sulfur, then fractionated upon reaction with O2 produced by oxygenic photosynthesis. Preservation of this positive 34S offset requires that: 1) sulfide was only partially (50­­-80%) consumed by oxidation, meaning H2S was locally more abundant (or more rapidly produced) than O2, and 2) the majority of the sulfate produced via oxidation was not immediately reduced to sulfide, implying either that the sulfate pool was much larger than the sulfide pool, or that the sulfate formed near the mat surface was transported and reduced in another part of the system. Contrastingly, older microbialite facies (> 2.7 Ga; Thomazo et al., 2013) appear to lack these observed 34S enrichments. Consequently, the onset of 34S enrichments could mark a shift in mat ecology, from communities dominated by anoxygenic photosynthesizers to cyanobacteria. Here, we test these hypotheses with new spatially resolved mm-scale trends in sulfur isotope measurements from pyritized stromatolites of the Vryburg Formation, sampled in the lower part of the BH1-Sacha core. Millimeter

  19. Flow banding in basaltic pillow lavas from the Early Archean Hooggenoeg Formation, Barberton Greenstone Belt, South Africa

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    Robins, Brian; Sandstå, Nils Rune; Furnes, Harald; de Wit, Maarten

    2010-07-01

    Well-preserved pillow lavas in the uppermost part of the Early Archean volcanic sequence of the Hooggenoeg Formation in the Barberton Greenstone Belt exhibit pronounced flow banding. The banding is defined by mm to several cm thick alternations of pale green and a dark green, conspicuously variolitic variety of aphyric metabasalt. Concentrations of relatively immobile TiO2, Al2O3 and Cr in both varieties of lava are basaltic. Compositional differences between bands and variations in the lavas in general have been modified by alteration, but indicate mingling of two different basalts, one richer in TiO2, Al2O3, MgO, FeOt and probably Ni and Cr than the other, as the cause of the banding. The occurrence in certain pillows of blebs of dark metabasalt enclosed in pale green metabasalt, as well as cores of faintly banded or massive dark metabasalt, suggest that breakup into drops and slugs in the feeder channel to the lava flow initiated mingling. The inhomogeneous mixture was subsequently stretched and folded together during laminar shear flow through tubular pillows, while diffusion between bands led to partial homogenisation. The most common internal pattern defined by the flow banding in pillows is concentric. In some pillows the banding defines curious mushroom-like structures, commonly cored by dark, variolitic metabasalt, which we interpret as the result of secondary lateral flow due to counter-rotating, transverse (Dean) vortices induced by the axial flow of lava towards the flow front through bends, generally downward, in the tubular pillows. Other pillows exhibit weakly-banded or massive, dark, variolitic cores that are continuous with wedge-shaped apophyses and veins that intrude the flow banded carapace. These cores represent the flow of hotter and less viscous slugs of the dark lava type into cooled and stiffened pillows.

  20. Evidence for ancient atmospheric xenon in Archean rocks and implications for the early evolution of the atmosphere

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    Pujol, M.; Marty, B.; Burnard, P.; Hofmann, A.

    2012-12-01

    The initial atmospheric xenon isotopic composition has been much debated over the last 4 decades. A Non radiogenic Earth Atmospheric xenon (NEA-Xe) composition has been proposed to be the best estimate of the initial signature ([1]). NEA-Xe consists of modern atmospheric Xe without fission (131-136Xe) or radioactive decay (129Xe) products. However, the isotope composition of such non-radiogenic xenon is very different to that of potential cosmochemical precursors such as solar or meteoritic Xe, as it is mass-fractionated by up to 3-4 % per amu relative to the potential precursors, and it is also elementally depleted relative to other noble gases. Because the Xe isotopic composition of the Archean appears to be intermediate between that of these cosmochemical end-members and that of the modern atmosphere, we argued that isotopic fractionation of atmospheric xenon did not occur early in Earth's history by hydrodynamic escape, as postulated by all other models ([1], [2], [3]), but instead was a continuous, long term process that lasted during at least the Hadean and Archean eons. Taken at face value, the decrease of the Xe isotopic fractionation from 1.6-2.1 % amu-1 3.5 Ga ago ([4]) to 1 % amu-1 3.0 Ga ago (Ar-Ar age in fluid inclusions trapped in quartz from the same Dresser Formation, [5]) could reflect a secular variation of the atmospheric Xe signature. Nevertheless, up until now, all data showing an isotopic mass fractionation have been measured in rocks and fluids from the same formation (Dresser Formation, Western Australia, aged 3.5 Ga), and have yet to be confirmed in rocks from different locations. In order to better constrain xenon isotopic fractionation of the atmosphere through time, we decided to analyze barites from different ages, geological environments and metamorphism grade. We started this study with barite from the Fig Tree Formation (South Africa, aged 3.26 Ga). This barite was sampled in old mines so have negligible modern exposure time. It is

  1. Early mantle dynamics inferred from 142Nd variations in Archean rocks from southwest Greenland

    DEFF Research Database (Denmark)

    Rizo, Hanika; Boyet, Maud; Blichert-Toft, Janne

    2013-01-01

    of the Greenland samples from a source formed in the Hadean. This mantle source is the oldest yet identified on Earth and therefore provides key information about the nature and evolution of early-differentiated reservoirs. In contrast, modern mantle-derived rocks from around the world do not have Nd-142 anomalies......The composition and evolution of the silicate Earth during Hadean/Eoarchean times are widely debated and largely unknown due to the sparse geological record preserved from Earth's infancy. The short-lived Sm-146-Nd-142 chronometer applied to 3.8-3.7 Ga old mantle-derived amphibolites from the Isua...... Supracrustal Belt (ISB) in southwest Greenland has revealed ubiquitous Nd-142 excesses in these rocks compared to modern samples and terrestrial Nd standards. Because the parent isotope, Sm-146, was extant only during the first few hundred million years of Solar System history, this implies derivation...

  2. Transfer and partitioning of energy and mass through seafloor hydrothermal systems: comparative studies at the Ridge2000 Integrated Study Sites (ISS) (Invited)

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    Tivey, M. K.

    2010-12-01

    Seafloor hydrothermal systems are major players in the transfer of mass and energy from the mantle and crust to the ocean and biosphere. Over the past thirty years, much has been learned about this transfer to the ocean, but considerably less is known about the transfer to the biosphere. Study of hydrothermal systems in a diverse range of geologic settings has shown relationships between spreading rate and hydrothermal heat flux, substrate composition (including rock geochemistry, presence/absence of sediment) and hydrothermal fluid composition, and magmatic/tectonic events and temporal variability of fluid composition (e.g., German and Von Damm, Treatise On Geochemistry, 2004; Baker et al. AGU Monograph Series 91, 1995). Studies in arc and back-arc settings are documenting the effects of magmatic acid volatiles on fluid-rock reaction and fluid and vent deposit compositions (e.g., Ishibashi and Urabe, Backarc Basins: Tectonics and Magmatism, 1995). These comparative studies in a wide range of geologic settings, including at the three Ridge2000 ISS, have provided a fairly good understanding of the flux of heat and many elements to the ocean associated with high temperature seafloor hydrothermal systems. Considerably less is known, however, about the partitioning of heat and mass (particularly metals and sulfur) in hydrothermal systems. The deposits that form at vent sites are intimately linked within paths of energy and mass transport from the mantle and crust to the oceans. Transport differs greatly through different types of deposits (e.g., black smokers, white smokers/diffusers, flanges). Estimates of heat flux from measured temperatures of flow (unless integrated over and around an entire vent field) require an understanding of the partitioning of flow between focused black smokers and more diffuse flow from diffusers, flanges, and surfaces of deposits, and from the igneous substrate. Estimates of mass flux into the ocean require an understanding of the

  3. Evidence of early Archean crust in northwest Gondwana, from U-Pb and Hf isotope analysis of detrital zircon, in Ediacaran surpacrustal rocks of northern Spain

    Science.gov (United States)

    Naidoo, Thanusha; Zimmermann, Udo; Vervoort, Jeff; Tait, Jenny

    2018-03-01

    The Mora Formation (Narcea Group) is one of the oldest Precambrian supracrustal successions in northern Spain. Here, we use U-Pb and in situ Hf isotope analysis on detrital zircon to determine its age and provenance. The youngest U-Pb dates constrain the maximum depositional age of the Mora Formation at 565 ± 11 Ma. Results indicate: (1) a dominant Ediacaran zircon population (33%; 565-633 Ma, Cadomian) within a spectrum of Neoproterozoic ages (40%; 636-996 Ma); and (2) smaller Mesoproterozoic (5%; 1004-1240 Ma), Palaeoproterozoic (11%; 1890-2476 Ma) and Archean (11%; 2519-3550 Ma) populations. Results here do not point to one specific cratonic source area; instead, detritus may have been derived from the West African craton and Amazonia, or even the concealed Iberian basement. The lack of 1.3-1.8 Ga grains suggests exclusion of the Sahara Craton as a major source, but this is not certain. This mixed composition favours a complex source history with reworking of detritus across terrane/craton boundaries. Hafnium isotope compositions indicate a range of crustal and juvenile sources, with initial ɛHf values between -15.8 and 11.1, and Hf model ages from 0.8 to 3.7 Ga. For Neoproterozoic zircons (80%), juvenile components (ɛHf(i) +10) may be related to Rodinia fragmentation and the onset of an active margin setting leading to the Cadomian orogeny. Palaeoproterozoic to Paleoarchean grains (20%) all have negative ɛHf values and Meso- to Eoarchean Hf model ages. This indicates an early (Archean) sialic crustal component for northwestern Gondwana.

  4. Venus and the Archean Earth: Thermal considerations

    International Nuclear Information System (INIS)

    Sleep, N.H.

    1989-01-01

    The Archean Era of the Earth is not a direct analog of the present tectonics of Venus. In this regard, it is useful to review the state of the Archean Earth. Most significantly, the temperature of the adiabatic interior of the Earth was 200 to 300 C hotter than the current temperature. Preservation biases limit what can be learned from the Archean record. Archean oceanic crust, most of the planetary surface at any one time, has been nearly all subducted. More speculatively, the core of the Earth has probably cooled more slowly than the mantle. Thus the temperature contrast above the core-mantle boundary and the vigor of mantle plumes has increased with time on the Earth. The most obvious difference between Venus and the present Earth is the high surface temperature and hence a low effective viscosity of the lithosphere. In addition, the temperature contrast between the adiabatic interior and the surface, which drives convection, is less on Venus than on the Earth. It appears that the hot lithosphere enhanced tectonics on the early Venus significantly enough that its interior cooled faster than the Earth's. The best evidence for a cool interior of Venus comes from long wavelength gravity anomalies. The low interior temperatures retard seafloor spreading on Venus. The high surface temperatures on Venus enhance crustal deformation. That is, the lower crust may become ductile enough to permit significant flow between the upper crust and the mantle. There is thus some analogy to modern and ancient areas of high heat flow on the Earth. Archean crustal blocks typically remained stable for long intervals and thus overall are not good analogies to the deformation style on Venus

  5. High Ni in Archean tholeiites

    Science.gov (United States)

    Arndt, Nicholas T.

    1991-03-01

    Archean tholeiites generally have higher Ni, Co. Cr and Fe than most younger tholeiites with similar MgO contents. These characteristics cannot be attributed to high T or P batch melting in the Archean mantle, because, although such melts are enriched in siderophile elements, they have higher MgO than normal tholeiites. As primary melts fractionate to lower MgO, they lose Ni, Co and Cr. Nor can the differences between Archean and younger tholeiites be attributed to secular variation in mantle compositions because Archean komatiites have Ni, Co, Cr contents similar to modern (Gorgona) komatiites. It is suggested that the high siderophile element content of Archean tholeiites results from mixing of either komatiitic with basaltic magmas, as might occur in an ascending, melting mantle plume or column, or of komatiite and more evolved rocks, as may take place when komatiite encounters and assimilates crustal rocks.

  6. An Archean Biosphere Initiative

    Science.gov (United States)

    Anbar, A. D.; Boyd, E. S.; Buick, R.; Claire, M.; DesMarais, D.; Domagal-Goldman, D.; Eigenbrode, J.; Erwin, D.; Freeman, K.; Hazen, R.; hide

    2011-01-01

    The search for life on extrasolar planets will necessarily focus on the imprints of biolgy on the composition of planetary atmospheres. The most notable biological imprint on the modern terrestrial atmosphere is the presence of 21 % O2, However, during most of the past 4 billion years, life and the surface environments on Earth were profoundly different than they are today. It is therefore a major goal of the astrobiology community to ascertain how the O2 content of the atmosphere has varied with time. and to understand the causes of these variations. The NAI and NASA Exobiology program have played critical roles in developing our current understanding of the ancient Earth's atmosphere, supporting diverse observational, analytical, and computational research in geoscience, life science, and related fields. In the present incarnation of the NAI, ongoing work is investigating (i) variations in atmospheric O2 in the Archean to the Cambrian, (ii) characterization of the redox state of the oceans shortly before, during and after the Great Oxidation Event (GOE), and (iii) unraveling the complex connections between environmental oxygenation, global climate, and the evolution of life.

  7. Evolution of the Dharwar Craton: a terrain of early Archean crustal stability, long term orogenic cycles and large scale palaeobiological activity

    International Nuclear Information System (INIS)

    Srinivasan, R.; Naqvi, S.M.

    1988-01-01

    Traceable history of the Dharwar Craton goes back to approximately 3400 m.y. old tonalitic to trondhjemitic fundamental gneiss whose REE composition indicates its derivation from a preexisting basalt which apparently had very short time of crustal residence. The fundamental gneiss is preserved only as rare relicts in the vast gneissic complex of the Indian Peninsula (the Peninsular Gneiss), and as pebbles in the conglomerates of the Archean Dharwar sequence. Study of these relicts, shows evidence of a deformation episode prior to the deposition of the high- and low-grade Dharwar supracrustal sequence. The Dharwar supracrustal sequence is briefly described. Geochemistry of the volcanic and sedimentary rocks of the Dharwar supracrustal belts are examined

  8. A thermoelectric cap for seafloor hydrothermal vents

    International Nuclear Information System (INIS)

    Xie, Yu; Wu, Shi-jun; Yang, Can-jun

    2016-01-01

    Highlights: • We developed a thermoelectric cap (TC) to harvest hydrothermal energy. • The TC was deployed at a hydrothermal vent site near Kueishantao islet, Taiwan. • The TC monitored the temperature of the hydrothermal fluids during the field test. • The TC could make the thermal energy of hydrothermal fluids a viable power source. - Abstract: Long-term in situ monitoring is crucial to seafloor scientific investigations. One of the challenges of operating sensors in seabed is the lifespan of the sensors. Such sensors are commonly powered by batteries when other alternatives, such as tidal or solar energy, are unavailable. However, the batteries have a limited lifespan and must be recharged or replaced periodically, which is costly and impractical. A thermoelectric cap, which harvests the thermal energy of hydrothermal fluids through a conduction pipe and converts the heat to electrical energy by using thermoelectric generators, was developed to avoid these inconveniences. The thermoelectric cap was combined with a power and temperature measurement system that enables the thermoelectric cap to power a light-emitting diode lamp, an electronic load (60 Ω), and 16 thermocouples continuously. The thermoelectric cap was field tested at a shallow hydrothermal vent site near Kueishantao islet, which is located offshore of northeastern Taiwan. By using the thermal gradient between hydrothermal fluids and seawater, the thermoelectric cap obtained a sustained power of 0.2–0.5 W during the field test. The thermoelectric cap successfully powered the 16 thermocouples and recorded the temperature of the hydrothermal fluids during the entire field test. Our results show that the thermal energy of hydrothermal fluids can be an alternative renewable power source for oceanographic research.

  9. Anhydrite precipitation in seafloor hydrothermal systems

    Science.gov (United States)

    Theissen-Krah, Sonja; Rüpke, Lars H.

    2016-04-01

    The composition and metal concentration of hydrothermal fluids venting at the seafloor is strongly temperature-dependent and fluids above 300°C are required to transport metals to the seafloor (Hannington et al. 2010). Ore-forming hydrothermal systems and high temperature vents in general are often associated with faults and fracture zones, i.e. zones of enhanced permeabilities that act as channels for the uprising hydrothermal fluid (Heinrich & Candela, 2014). Previous numerical models (Jupp and Schultz, 2000; Andersen et al. 2015) however have shown that high permeabilities tend to decrease fluid flow temperatures due to mixing with cold seawater and the resulting high fluid fluxes that lead to short residence times of the fluid near the heat source. A possible mechanism to reduce the permeability and thereby to focus high temperature fluid flow are mineral precipitation reactions that clog the pore space. Anhydrite for example precipitates from seawater if it is heated to temperatures above ~150°C or due to mixing of seawater with hydrothermal fluids that usually have high Calcium concentrations. We have implemented anhydrite reactions (precipitation and dissolution) in our finite element numerical models of hydrothermal circulation. The initial results show that the precipitation of anhydrite efficiently alters the permeability field, which affects the hydrothermal flow field as well as the resulting vent temperatures. C. Andersen et al. (2015), Fault geometry and permeability contrast control vent temperatures at the Logatchev 1 hydrothermal field, Mid-Atlantic Ridge, Geology, 43(1), 51-54. M. D. Hannington et al. (2010), Modern Sea-Floor Massive Sulfides and Base Metal Resources: Toward an Estimate of Global Sea-Floor Massive Sulfide Potential, in The Challenge of Finding New Mineral Resources: Global Metallogeny, Innovative Exploration, and New Discoveries, edited by R. J. Goldfarb, E. E. Marsh and T. Monecke, pp. 317-338, Society of Economic Geologists. Heinrich, C. A., and P. A. Candela (2014), 13.1 - Fluids and Ore Formation in the Earth's Crust, in Treatise on Geochemistry (Second Edition), edited by H. D. Holland and K. K. Turekian, pp. 1-28, Elsevier, Oxford. Jupp, T., and A. Schultz (2000), A thermodynamic explanation for black smoker temperatures, Nature, 403(6772), 880-883.

  10. Multiple sources of selenium in ancient seafloor hydrothermal systems: Compositional and Se, S, and Pb isotopic evidence from volcanic-hosted and volcanic-sediment-hosted massive sulfide deposits of the Finlayson Lake District, Yukon, Canada

    Science.gov (United States)

    Layton-Matthews, Daniel; Leybourne, Matthew I.; Peter, Jan M.; Scott, Steven D.; Cousens, Brian; Eglington, Bruce M.

    2013-09-01

    Volcanic-hosted massive sulfide (VHMS) and volcanic-sediment-hosted massive sulfide (VSHMS; i.e., hosted by both volcanic and sedimentary rocks) deposits in the Finlayson Lake District, Yukon, Canada, provide a unique opportunity to study the influence of seafloor and sub-seafloor hydrothermal processes on the formation of Se-poor (GP4F VHMS deposit; 7 ppm Se average), intermediate (Kudz Ze Kayah—KZK VHMS deposit; 200 ppm Se average), and Se-enriched (Wolverine VSHMS deposit; 1100 ppm Se average) mineralization. All three deposits are hosted by mid-Paleozoic (˜360-346 Ma) felsic volcanic rocks, but only the Wolverine deposit has voluminous coeval carbonaceous argillites (black shales) in the host rock package. Here we report the first application of Se isotope analyses to ancient seafloor mineralization and use these data, in conjunction with Pb and S isotope analyses, to better understand the source(s) and depositional process(es) of Se within VHMS and VSHMS systems. The wide range of δ82Se (-10.2‰ to 1.3‰, relative to NIST 3149), δ34S (+2.0‰ to +12.8‰ CDT), and elevated Se contents (up to 5865 ppm) within the Wolverine deposit contrast with the narrower range of δ82Se (-3.8‰ to -0.5‰), δ34S (9.8‰ to 13.0‰), and lower Se contents (200 ppm average) of the KZK deposit. The Wolverine and KZK deposits have similar sulfide depositional histories (i.e., deposition at the seafloor, with concomitant zone refining). The Se in the KZK deposit is magmatic (leaching or degassing) in origin, whereas the Wolverine deposit requires an additional large isotopically negative Se source (i.e. ˜-15‰ δ82Se). The negative δ82Se values for the Wolverine deposit are at the extreme light end for measured terrestrial samples, and the lightest observed for hypogene sulfide minerals, but are within calculated equilibrium values of δ82Se relative to NIST 3149 (˜30‰ at 25 °C between SeO4 and Se2-). We propose that the most negative Se isotope values at the

  11. U Pb and Lu Hf isotope record of detrital zircon grains from the Limpopo Belt Evidence for crustal recycling at the Hadean to early-Archean transition

    Science.gov (United States)

    Zeh, Armin; Gerdes, Axel; Klemd, Reiner; Barton, J. M., Jr.

    2008-11-01

    Detrital zircon grains from Beit Bridge Group quartzite from the Central Zone of the Limpopo Belt near Musina yield mostly ages of 3.35-3.15 Ga, minor 3.15-2.51 Ga components, and numerous older grains grouped at approximately 3.4, 3.5 and 3.6 Ga. Two grains yielded concordant Late Hadean U-Pb ages of 3881 ± 11 Ma and 3909 ± 26 Ma, which are the oldest zircon grains so far found in Africa. The combined U-Pb and Lu-Hf datasets and field relationships provide evidence that the sedimentary protolith of the Beit Bridge Group quartzite was deposited after the emplacement of the Sand River Gneisses (3.35-3.15 Ga), but prior to the Neoarchean magmatic-metamorphic events at 2.65-2.60 Ga. The finding of abundant magmatic zircon detritus with concordant U-Pb ages of 3.35-3.15 Ga, and 176Hf/ 177Hf of 0.28066 ± 0.00004 indicate that the Sand River Gneiss-type rocks were a predominant source. In contrast, detrital zircon grains older than approximately 3.35 Ga were derived from the hinterland of the Limpopo Belt; either from a so far unknown crustal source in southern Africa, possibly from the Zimbabwe Craton and/or a source, which was similar but not necessarily identical to the one that supplied the Hadean zircons to Jack Hills, Western Australia. The Beit Bridge Group zircon population at >3.35 Ga shows a general ɛHf t increase with decreasing age from ɛHf 3.9Ga = -6.3 to ɛHf 3.3-3.1Ga = -0.2, indicating that Hadean crust older than 4.0 Ga ( TDM = 4.45-4.36 Ga) was rejuvenated during magmatic events between >3.9 and 3.1 Ga, due to a successive mixing of crustal rocks with mantle derived magmas. The existence of a depleted mantle reservoir in the Limpopo's hinterland is reflected by the ˜3.6 Ga zircon population, which shows ɛHf 3.6Ga between -4.6 and +3.2. In a global context, our data suggest that a long-lived, mafic Hadean protocrust with some tonalite-trondhjemite-granodiorite constituents was destroyed and partly recycled at the Hadean/Archean transition, perhaps

  12. Drilling for the Archean Roots of Life and Tectonic Earth in the Barberton Mountains

    Directory of Open Access Journals (Sweden)

    Nicola McLoughlin

    2009-09-01

    Full Text Available In the Barberton Scientific Drilling Program (BSDP we successfully completed three drill holes in 2008 across strategically selected rock formations in the early Archean Barberton Greenstone Belt, South Africa. This collaborative project’s goal is to advance understanding of geodynamic and biogeochemical processes of the young Earth. The program aims to better define and characterize Earth’s earliest preserved ocean crust shear zones and microbial borings in Archean basaltic glass, and to identify biogeochemical fingerprints of ancient ecological niches recorded in rocks. The state-of-the-art analytical and imaging work will address the question of earliest plate tectonics in the Archean, the δ18O composition, the redox state and temperature of Archean seawater, and the origin of life question.

  13. NanoSIMS analysis of Archean fossils and biomarkers

    International Nuclear Information System (INIS)

    Kilburn, M.R.; Wacey, D.

    2008-01-01

    The study of fossils and biomarkers from Archean rocks is of vital importance to reveal how life arose on Earth and what we might expect to find on other planets such as Mars. The Cameca NanoSIMS 50 has the unique ability to measure stable isotopes and map biologically relevant elements at the micron-scale, in situ. This makes it the perfect tool for testing the biogenicity of a range of putative biomarkers from early Archean rocks (∼3.50 billion-year-old). NanoSIMS has been used to investigate ambient inclusion trails (AITs) in a 3.43 Ga beach sand deposit from the Pilbara craton, Western Australia. Chemical maps of the light elements necessary for life (C, N and O) and several transition metals commonly associated with biological processing (Ni, Zn and Fe), coupled with 13 C/ 12 C isotope ratios from carbonaceous linings, strongly suggest a biological component in the formation of AITs

  14. Two distinct origins for Archean greenstone belts

    Science.gov (United States)

    Smithies, R. Hugh; Ivanic, Tim J.; Lowrey, Jack R.; Morris, Paul A.; Barnes, Stephen J.; Wyche, Stephen; Lu, Yong-Jun

    2018-04-01

    Applying the Th/Yb-Nb/Yb plot of Pearce (2008) to the well-studied Archean greenstone sequences of Western Australia shows that individual volcanic sequences evolved through one of two distinct processes reflecting different modes of crust-mantle interaction. In the Yilgarn Craton, the volcanic stratigraphy of the 2.99-2.71 Ga Youanmi Terrane mainly evolved through processes leading to Th/Yb-Nb/Yb trends with a narrow range of Th/Nb ('constant-Th/Nb' greenstones). In contrast, the 2.71-2.66 Ga volcanic stratigraphy of the Eastern Goldfields Superterrane evolved through processes leading to Th/Yb-Nb/Yb trends showing a continuous range in Th/Nb ('variable-Th/Nb' greenstones). Greenstone sequences of the Pilbara Craton show a similar evolution, with constant-Th/Nb greenstone evolution between 3.13 and 2.95 Ga and variable-Th/Nb greenstone evolution between 3.49 and 3.23 Ga and between 2.77 and 2.68 Ga. The variable-Th/Nb trends dominate greenstone sequences in Australia and worldwide, and are temporally associated with peaks in granite magmatism, which promoted crustal preservation. The increasing Th/Nb in basalts correlates with decreasing εNd, reflecting variable amounts of crustal assimilation during emplacement of mantle-derived magmas. These greenstones are typically accompanied in the early stages by komatiite, and can probably be linked to mantle plume activity. Thus, regions such as the Eastern Goldfields Superterrane simply developed as plume-related rifts over existing granite-greenstone crust - in this case the Youanmi Terrane. Their Th/Nb trends are difficult to reconcile with modern-style subduction processes. The constant-Th/Nb trends may reflect derivation from a mantle source already with a high and constant Th/Nb ratio. This, and a lithological association including boninite-like lavas, basalts, and calc-alkaline andesites, all within a narrow Th/Nb range, resembles compositions typical of modern-style subduction settings. These greenstones are very

  15. Assessing the effects of ultraviolet radiation on the photosynthetic potential in Archean marine environments

    Science.gov (United States)

    Avila-Alonso, Dailé; Baetens, Jan M.; Cardenas, Rolando; de Baets, Bernard

    2017-07-01

    In this work, the photosynthesis model presented by Avila et al. in 2013 is extended and more scenarios inhabited by ancient cyanobacteria are investigated to quantify the effects of ultraviolet (UV) radiation on their photosynthetic potential in marine environments of the Archean eon. We consider ferrous ions as blockers of UV during the Early Archean, while the absorption spectrum of chlorophyll a is used to quantify the fraction of photosynthetically active radiation absorbed by photosynthetic organisms. UV could have induced photoinhibition at the water surface, thereby strongly affecting the species with low light use efficiency. A higher photosynthetic potential in early marine environments was shown than in the Late Archean as a consequence of the attenuation of UVC and UVB by iron ions, which probably played an important role in the protection of ancient free-floating bacteria from high-intensity UV radiation. Photosynthetic organisms in Archean coastal and ocean environments were probably abundant in the first 5 and 25 m of the water column, respectively. However, species with a relatively high efficiency in the use of light could have inhabited ocean waters up to a depth of 200 m and show a Deep Chlorophyll Maximum near 60 m depth. We show that the electromagnetic radiation from the Sun, both UV and visible light, could have determined the vertical distribution of Archean marine photosynthetic organisms.

  16. Granite-hosted molybdenite mineralization from Archean ...

    Indian Academy of Sciences (India)

    2013). The Bundelk- hand Tectonic Zone has now been established as an Archean ... The molybdenite is only encountered in geochemical analysis. (f) Mo vein is ...... Collins W J, Beams S D, White A J R and Chappell B W. 1982 Nature and ...

  17. Constraining Δ33S signatures of Archean seawater sulfate with carbonate-associated sulfate

    Science.gov (United States)

    Peng, Y.; Bao, H.; Bekker, A.; Hofmann, A.

    2017-12-01

    Non-mass dependent sulfur isotope deviation of S-bearing phases in Archean sedimentary strata, and expressed as Δ33S, has a consistent pattern, i.e., sulfide (pyrite) predominantly bear positive Δ33S values, while Paleoarchean sulfate (barite) has negative Δ33S values. This pattern was later corroborated by observations of negative Δ33S values in Archean volcanogenic massive sulfide deposits and negative Δ33S values in early diagenetic nodular pyrite with a wide range of δ34S values, which is thought to be due to microbial sulfate reduction. These signatures have provided a set of initial conditions for a mechanistic interpretation at physical chemistry level. Unlike the younger geological times when large bodies of seawater evaporite deposits are common, to expand seawater sulfate records, carbonate-associated sulfate (CAS) was utilized as a proxy for ancient seawater sulfate. CAS extracted from the Archean carbonates carries positive Δ33S values. However, CAS could be derived from pyrite oxidation following exposure to modern oxidizing conditions and/or during laboratory extraction procedures. It is, therefore, important for us understanding context of the overall early earth atmospheric condition to empirically confirm whether Archean seawater sulfate was generally characterized by negative Δ33S signatures. Combined δ18O, Δ17O, δ34S, and Δ33S analyses of sequentially extracted water-leachable sulfate (WLS) and acid-leachable sulfate (ALS = CAS) and δ34S and Δ33S analyses of pyrite can help to identify the source of extracted sulfate. We studied drill-core samples of Archean carbonates from the 2.55 Ga Malmani and Campell Rand supgroups, South Africa. Our preliminary results show that 1) neither WLS nor ALS were extracted from samples with extremely low pyrite contents (less than 0.05 wt.%); 2) extractable WLS and ALS is present in samples with relatively high pyrite contents (more than 1 wt.%), and that δ34S and Δ33S values of WLS, ALS, and

  18. Zircon's Archean of the Ural

    International Nuclear Information System (INIS)

    Krasnobaev, A.A.; Cherednichenko, N.V.

    2005-01-01

    The age of zircons from metamorphic rocks of the Taratashsky complex located on the Western slope of the South Urals was determined by the methods of U-Pb isotope dating. The age values obtained suggest a two-stage model of the complex evolution at early stages of its existence. The age of 2913±133 mln. years identifies the age of granulite metamorphism, while the age 2127±65 mln. years indicates the period of the most intensive transformations of the rocks within the complex, which were accompanied by occurrence of high-temperature diaphthorites [ru

  19. Diversity in the Archean Biosphere: New Insights from NanoSIMS

    Science.gov (United States)

    Oehler, Dorothy Z.; Robert, François; Walter, Malcolm R.; Sugitani, Kenichiro; Meibom, Anders; Mostefaoui, Smail; Gibson, Everett K.

    2010-05-01

    The origin of organic microstructures in the ˜3 Ga Farrel Quartzite is controversial due to their relatively poor state of preservation, the Archean age of the cherts in which they occur, and the unusual spindle-like morphology of some of the forms. To provide more insight into the significance of these microstructures, nano-scale secondary ion mass spectrometry (NanoSIMS) maps of carbon, nitrogen, sulfur, silicon, and oxygen were obtained for spheroidal and spindle-shaped constituents of the Farrel Quartzite assemblage. Results suggest that the structures are all bona fide ˜3 Ga microfossils. The spindles demonstrate an architecture that is remarkable for 3 Ga organisms. They are relatively large, robust, and morphologically complex. The NanoSIMS element maps corroborate their complexity by demonstrating an intricate, internal network of organic material that fills many of the spindles and extends continuously from the body of these structures into their spearlike appendages. Results from this study combine with previous morphological and chemical analyses to argue that the microstructures in the Farrel Quartzite comprise a diverse assemblage of Archean microfossils. This conclusion adds to a growing body of geochemical, stromatolitic, and morphological evidence that indicates the Archean biosphere was varied and well established by at least ˜3 Ga. Together, the data paint a picture of Archean evolution that is one of early development of morphological and chemical complexity. The evidence for Archean evolutionary innovation may augur well for the possibility that primitive life on other planets could adapt to adverse conditions by ready development of diversity in form and biochemistry.

  20. Photosynthesis in the Archean era.

    Science.gov (United States)

    Olson, John M

    2006-05-01

    The earliest reductant for photosynthesis may have been H2. The carbon isotope composition measured in graphite from the 3.8-Ga Isua Supercrustal Belt in Greenland is attributed to H2-driven photosynthesis, rather than to oxygenic photosynthesis as there would have been no evolutionary pressure for oxygenic photosynthesis in the presence of H2. Anoxygenic photosynthesis may also be responsible for the filamentous mats found in the 3.4-Ga Buck Reef Chert in South Africa. Another early reductant was probably H2S. Eventually the supply of H2 in the atmosphere was likely to have been attenuated by the production of CH4 by methanogens, and the supply of H2S was likely to have been restricted to special environments near volcanos. Evaporites, possible stromatolites, and possible microfossils found in the 3.5-Ga Warrawoona Megasequence in Australia are attributed to sulfur-driven photosynthesis. Proteobacteria and protocyanobacteria are assumed to have evolved to use ferrous iron as reductant sometime around 3.0 Ga or earlier. This type of photosynthesis could have produced banded iron formations similar to those produced by oxygenic photosynthesis. Microfossils, stromatolites, and chemical biomarkers in Australia and South Africa show that cyanobacteria containing chlorophyll a and carrying out oxygenic photosynthesis appeared by 2.8 Ga, but the oxygen level in the atmosphere did not begin to increase until about 2.3 Ga.

  1. Cool seafloor hydrothermal springs reveal global geochemical fluxes

    Science.gov (United States)

    Wheat, C. Geoffrey; Fisher, Andrew T.; McManus, James; Hulme, Samuel M.; Orcutt, Beth N.

    2017-10-01

    We present geochemical data from the first samples of spring fluids from Dorado Outcrop, a basaltic edifice on 23 M.y. old seafloor of the Cocos Plate, eastern Pacific Ocean. These samples were collected from the discharge of a cool hydrothermal system (CHS) on a ridge flank, where typical reaction temperatures in the volcanic crust are low (2-20 °C) and fluid residence times are short. Ridge-flank hydrothermal systems extract 25% of Earth's lithospheric heat, with a global discharge rate equivalent to that of Earth's river discharge to the ocean; CHSs comprise a significant fraction of this global flow. Upper crustal temperatures around Dorado Outcrop are ∼15 °C, the calculated residence time is V, U, Mg, phosphate, Si and Li are different. Applying these observed differences to calculated global CHS fluxes results in chemical fluxes for these ions that are ≥15% of riverine fluxes. Fluxes of K and B also may be significant, but better analytical resolution is required to confirm this result. Spring fluids also have ∼50% less dissolved oxygen (DO) than bottom seawater. Calculations of an analytical model suggest that the loss of DO occurs primarily (>80%) within the upper basaltic crust by biotic and/or abiotic consumption. This calculation demonstrates that permeable pathways within the upper crust can support oxic water-rock interactions for millions of years.

  2. Sulfate was a trace constituent of Archean seawater

    DEFF Research Database (Denmark)

    Crowe, Sean Andrew; Paris, Guillaume; Katsev, Sergei

    2014-01-01

    In the low-oxygen Archean world (>2400 million years ago), seawater sulfate concentrations were much lower than today, yet open questions frustrate the translation of modern measurements of sulfur isotope fractionations into estimates of Archean seawater sulfate concentrations. In the water column...

  3. Diversification in the Archean Biosphere: Insight from NanoSIMS of Microstructures in the Farrel Quartzite of Australia

    Science.gov (United States)

    Oehler, D. Z.; Robert, F.; Walter, M. R.; Sugitani, K.; Meibom, A.; Mostefaoui, S.; Gibson, E. K.

    2010-01-01

    The nature of early life on Earth is difficult to assess because potential Early Archean biosignatures are commonly poorly preserved. Interpretations of such materials have been contested, and abiotic or epigenetic derivations have been proposed (summarized in [1]). Yet, an understanding of Archean life is of astrobiological importance, as knowledge of early evolutionary processes on Earth could provide insight to development of life on other planets. A recently-discovered assemblage of organic microstructures in approx.3 Ga charts of the Farrel Quartzite (FQ) of Australia [2-4] includes unusual spindle-like forms and a variety of spheroids. If biogenicity and syngeneity of these forms could be substantiated, the FQ assemblage would provide a new view of Archean life. Our work uses NanoSIMS to further assess the biogenicity and syngeneity of FQ microstructures. In prior NanoSIMS studies [5-6], we gained an understanding of nano-scale elemental distributions in undisputed microfossils from the Neoproterozoic Bitter Springs Formation of Australia. Those results provide a new tool with which to evaluate poorly preserved materials that we might find in Archean sediments and possibly in extraterrestrial materials. We have applied this tool to the FQ forms.

  4. Reconciling "Whiffs" of O2 with the Archean MIF S Record: Insights from Sulfide Oxidation Experiments

    Science.gov (United States)

    Johnson, A.; Reinhard, C. T.; Romaniello, S. J.; Greaney, A. T.; Garcia-Robledo, E.; Revsbech, N. P.; Canfield, D. E.; Lyons, T. W.; Anbar, A. D.

    2016-12-01

    The Archean-Proterozoic transition is marked by the first appreciable accumulation of O2 in Earth's oceans and atmosphere at 2.4 billion years ago (Ga). However, this Great Oxidation Event (GOE) is not the first evidence for O2 in Earth's surface environment. Paleoredox proxies preserved in ancient marine shales (Mo, Cr, Re, U) suggest transient episodes of oxidative weathering before the GOE, perhaps as early as 3.0 Ga. One marine shale in particular, the 2.5 Ga Mount McRae Shale of Western Australia, contains a euxinic interval with Mo enrichments up to 50 ppm. This enrichment is classically interpreted as the result of oxidative weathering of sulfides on the continental surface. However, prior weathering models based on experiments suggested that sulfides require large amounts of O2 [>10-4 present atmospheric level (PAL) pO2] to produce this weathering signature, in conflict with estimates of Archean pO2 from non-mass-dependent (NMD) sulfur isotope anomalies (molybdenite from 3 - 700 nM O2 (equivalent at equilibrium to 10-5 - 10-3 PAL) to measure oxidation kinetics as a function of the concentration of dissolved O2. We measured rates by injecting oxygenated water at a steady flow rate and monitoring dissolved O2 concentrations with LUMOS sensors. Our data extend the O2 range explored in pyrite oxidation experiments by three orders of magnitude and provide the first rates for molybdenite oxidation at O2 concentrations potentially analogous to those characteristic of the Archean atmosphere. Our results show that pyrite and molybdenite oxidize significantly more rapidly at lower O2 levels than previously thought. As a result, our revised weathering model demonstrates that the Mo enrichments observed in late Archean marine shales are potentially attainable at extremely low atmospheric pO2 values (e.g., <10-5 PAL), reconciling large sedimentary Mo enrichments with co-occurring NMD sulfur isotope anomalies.

  5. Geostable molecules and the Late Archean 'Whiff of Oxygen'

    Science.gov (United States)

    Summons, R. E.; Illing, C. J.; Oduro, H. D.; French, K. L.; Ono, S.; Hallmann, C.; Strauss, H.

    2012-12-01

    Geoscientists continue to debate the course of oxygenation of Earth's surface environment. The prevailing scenarios include the one articulated by Cloud, Holland and Walker which proposes an initially anoxic or very low O2 atmosphere but one where oxygen-releasing Photosystem II appeared early. A strong imbalance between sources & sinks kept the atmospheric pO2 low until the 'Great Oxidation Event' or GOE at c. 2.45 Ga. An alternative scenario is that the GOE marks the first appearance of oxygen-releasing photosynthesis (Kopp et al., 2005). However, there is a wealth of geochemical and paleontological data that is consistent with the presence of both cyanobacteria (e.g. Bosak et al., 2009) and traces of environmental oxygen (e.g. Anbar et al., 2007) several hundred million years prior to the GOE. Here we report new studies of 2.7-2.5 Ga sedimentary rocks from the Transvaal Supergroup of the Kaapvaal Craton and from the Mt. Bruce Supergroup of the Pilbara Craton. We used improved analytical techniques which identified and excluded minor sources of contaminating hydrocarbons. We also focused on mineral-occluded hydrocarbons that show distribution patterns that co-vary with lithology and replicated earlier identifications of molecular fossils that require oxygen for their biosynthesis (Waldbauer et al., 2008, 2011). Some sediment horizons in the studied sections contain diagenetic products of pigments characteristic of phototrophic green sulfur bacteria and their co-variance with inorganic proxies, each leading to similar paleoenvironmental reconstructions and confirming the authenticity of this signal. The carotenoid-derived biomarkers, although diagnostic for anoxygenic phototrophs, indicate that the seas of the Hamersley and Transvaal Basins provided an intermittent supply of hydrogen sulfide to the photic zone. Indirectly, this suggests replenishment of the marine sulfate pool from the oxidative weathering of metal sulfides. Organic sulfur in these same sediments

  6. Mobility of nutrients and trace metals during weathering in the late Archean

    Science.gov (United States)

    Hao, Jihua; Sverjensky, Dimitri A.; Hazen, Robert M.

    2017-08-01

    The evolution of the geosphere and biosphere depends on the availability of bio-essential nutrients and trace metals. Consequently, the chemical and isotopic variability of trace elements in the sedimentary record have been widely used to infer the existence of early life and fluctuations in the near-surface environment on the early Earth, particularly fluctuations in the redox state of the atmosphere. In this study, we applied late Archean weathering models (Hao et al., 2017), developed to estimate the behavior of major elements and the composition of late Archean world average river water, to explore the behavior of nutrient and trace metals and their potential for riverine transport. We focused on P, Mn, Cr, and Cu during the weathering of olivine basalt. In our standard late Archean weathering model (pCO2,g = 10-1.5 bars, pH2,g = 10-5.0 bars), crustal apatite was totally dissolved by the acidic rainwater during weathering. Our model quantitatively links the pCO2,g of the atmosphere to phosphate levels transported by rivers. The development of late Archean river water (pH = 6.4) resulted in riverine phosphate of at least 1.7 μmolar, much higher than at the present-day. At the end of the early Proterozoic snowball Earth event when pCO2,g could be 0.01-0.10 bars, river water may have transported up to 70 μmolar phosphate, depending on the availability of apatite, thereby stimulating high levels of oxygenic photosynthesis in the marine environment. Crustal levels of Mn in olivine dissolved completely during weathering, except at large extents of weathering where Mn was stored as a component of a secondary carbonate mineral. The corresponding Mn content of river water, about 1.2 μmolar, is higher than in modern river water. Whiffs of 10-5 mole O2 gas or HNO3 kg-1 H2O resulted in the formation of pyrolusite (MnO2) and abundant hematite and simultaneous dramatic decreases in the concentration of Mn(II) in the river water. Chromite dissolution resulted in negligible

  7. An investigation of the Archean climate using the NCAR CCm

    International Nuclear Information System (INIS)

    Jenkins, G.S.

    1991-01-01

    The Archean (2.5 to 3.8 billion years ago) is of interest climatically, because of the 'Faint-Young Sun Paradox', which can be characterized by the Sun's reduced energy output. This lower energy output leads to a frozen planet if the climate existed as it does today. But, the geologic record shows that water was flowing at the earth's surface 3.8 billion years ago. Energy Balance Models (EBMs) and one-dimensional radiative-convective (1DRC) models predict a frozen planet for this time period, unless large carbon dioxide (CO2) concentrations exist in the Archean atmosphere. The goal is to explore the Archean climate with the National Center for Atmospheric Research (NCAR), Community Climate Model (CCM). The search for negative feedbacks to explain the 'Faint-Young Sun Paradox' is the thrust of this study. This study undertakes a series of sensitivity simulations which first explores individual factors that may be important for the Archean. They include rotation rate, lower solar luminosity, and land fraction. Then, these climatic factors along with higher CO2 concentrations are combined into a set of experiments. A faster rotation rate may have existed in the Archean. The faster rotation rate simulations show warmer globally averaged surface temperatures that are caused by a 20 percent decrease in the total cloud fraction. The smaller cloud fraction is brought about by dynamical changes. A global ocean is a possibility for the Archean. A global ocean simulation predicts 4 K increase in global mean surface temperatures compared to the present-day climate control

  8. Evaluating the earliest traces of Archean sub-seafloor life by NanoSIMS

    Science.gov (United States)

    Mcloughlin, N.; Grosch, E. G.; Kilburn, M.; Wacey, D.

    2012-12-01

    The Paleoarchean sub-seafloor has been proposed as an environment for the emergence of life with titanite microtextures in pillow lavas argued to be the earliest traces of microbial micro-tunneling (Furnes et al. 2004). Here we use a nano-scale ion microprobe (NanoSIMS) to evaluate possible geochemical traces of life in 3.45 Ga pillow lavas of the Barberton Greenstone Belt, South Africa. We investigated both surface and drill core samples from the original "Biomarker" outcrop in the Hooggenoeg Fm. Pillow lava metavolcanic glass contain clusters of segmented microcrystalline titanite filaments, ~4μm across and sedimentary sulfides (δ34S = +8 to -23‰). We propose that the Hooggenoeg sulfides probably formed during early fluid-rock-microbe interaction involving sulfate-reducing microbes (c.f. Rouxel et al. 2008). The pillow lavas were then metamorphosed, the glass transformed to a greenschist facies assemblage and titanite growth encapsulated the microbial sulfides. In summary, the extreme sulfur isotope fractionations reported here independently point towards the potential involvement of microbes in the alteration of Archean volcanic glass. In situ sulfur isotope analysis of basalt-hosted sulfides may provide an alternative approach to investigating the existence of an Archean sub-seafloor biosphere that does not require the mineralization of early microbial microborings with organic linings.

  9. Decreasing µ142Nd Variation in the Archean Convecting Mantle from 4.0 to 2.5 Ga: Heterogeneous Domain Mixing or Crustal Recycling?

    Science.gov (United States)

    Brandon, A. D.; Debaille, V.

    2014-12-01

    The 146Sm-142Nd (t1/2=68 Ma) chronometer can be used to examine silicate differentiation in the first 400 Ma of Earth history. Early fractionation between Sm and Nd is recorded in cratonic Archean rocks in their 142Nd/144Nd ratios that that deviate up to ±20 ppm, or μ142Nd - ppm deviation relative to the present-day convecting mantle at 0. These values likely record early extraction of incompatible trace element (ITE) enriched material with -μ142Nd, either as crust or late stage residual melt from a magma ocean, and resulting in a complimentary ITE depleted residual mantle with +μ142Nd. If this early-formed ITE-enriched material was re-incorporated rapidly back into the convecting mantle, both ITE-enriched and ITE-depleted mantle domains would have been established in the Hadean. Alternatively, if it was early-formed crust that remained stable it could have slowly eroded and progressively remixed into the convecting mantle as subducted sediment during the Archean. Each of these scenarios could potentially explain the decrease in the maximum variation in µ142Nd from ±20 at 4.0 Ga to 0 at 2.5 Ga [1,2,3]. In the scenario where these variations reflect mixing of mantle domains, this implies long mantle mixing times of greater than 1 Ga in the Archean in order to preserve the early-formed heterogeneities. This can be achieved in a stagnant lid tectonic regime in the Archean with sporadic and short subduction cycles [2]. This scenario would also indicate that mixing times in the convecting mantle were much slower than the previously proposed 100 Ma in the Hadean and Archean. In the alternative scenario, sediment with -µ142Nd was progressively mixed into the mantle via subduction in the Archean [3]. This scenario doesn't require slow mantle mixing times or a stagnant-lid regime. It requires crustal resident times of up to 750 Ma to maintain a steady supply of ancient sediment recycling over the Archean. Each of these scenarios evoke very contrasting conditions for

  10. Where are uranium and thorium stored in the Archean basement

    Energy Technology Data Exchange (ETDEWEB)

    Schwinner, R

    1949-01-01

    The author advances a theory which makes it possible to predict where prospecting for new deposits of uranium and thorium should prove successful. According to this theory, such deposits occur chiefly where the equatorial and the meridional branches of the oldest primitive rock systems cross one another. An outline of the earth's Archean basement is included.

  11. Hydrothermal Processes in the Archean - New Insights from Imaging Spectroscopy

    NARCIS (Netherlands)

    Ruitenbeek, F.J.A. van

    2007-01-01

    The aim of this research was to gain new insights in fossil hydrothermal systems using airborne imaging spectroscopy. Fossil submarine hydrothermal systems in Archean greenstone belts and other geologic terranes are important because of their relationship with volcanic massive sulfide (VMS) mineral

  12. Geologic evolution of iron quadrangle on archean and early proterozoic

    International Nuclear Information System (INIS)

    Machado, N.; Noce, C.M.; Ladeira, E.A.

    1989-01-01

    The preliminary results of U-Pb geochronology of iron quadrangle. Brazil are presented, using the Davis linear regression program for determining of intersection concordance-discord and for estimation the associate mistakes. (C.G.C.)

  13. Late Archean Surface Ocean Oxygenation (Invited)

    Science.gov (United States)

    Kendall, B.; Reinhard, C.; Lyons, T. W.; Kaufman, A. J.; Anbar, A. D.

    2009-12-01

    Oxygenic photosynthesis must have evolved by 2.45-2.32 Ga, when atmospheric oxygen abundances first rose above 0.001% present atmospheric level (Great Oxidation Event; GOE). Biomarker evidence for a time lag between the evolution of cyanobacterial oxygenic photosynthesis and the GOE continues to be debated. Geochemical signatures from sedimentary rocks (redox-sensitive trace metal abundances, sedimentary Fe geochemistry, and S isotopes) represent an alternative tool for tracing the history of Earth surface oxygenation. Integrated high-resolution chemostratigraphic profiles through the 2.5 Ga Mt. McRae Shale (Pilbara Craton, Western Australia) suggest a ‘whiff’ of oxygen in the surface environment at least 50 M.y. prior to the GOE. However, the geochemical data from the Mt. McRae Shale does not uniquely constrain the presence or extent of Late Archean ocean oxygenation. Here, we present high-resolution chemostratigraphic profiles from 2.6-2.5 Ga black shales (upper Campbellrand Subgroup, Kaapvaal Craton, South Africa) that provide the earliest direct evidence for an oxygenated ocean water column. On the slope beneath the Campbellrand - Malmani carbonate platform (Nauga Formation), a mildly oxygenated water column (highly reactive iron to total iron ratios [FeHR/FeT] ≤ 0.4) was underlain by oxidizing sediments (low Re and Mo abundances) or mildly reducing sediments (high Re but low Mo abundances). After drowning of the carbonate platform (Klein Naute Formation), the local bottom waters became anoxic (FeHR/FeT > 0.4) and intermittently sulphidic (pyrite iron to highly reactive iron ratios [FePY/FeHR] > 0.8), conducive to enrichment of both Re and Mo in sediments, followed by anoxic and Fe2+-rich (ferruginous) conditions (high FeT, FePY/FeHR near 0). Widespread surface ocean oxygenation is suggested by Re enrichment in the broadly correlative Klein Naute Formation and Mt. McRae Shale, deposited ~1000 km apart in the Griqualand West and Hamersley basins

  14. Evolution of the Archean Mohorovičić discontinuity from a synaccretionary 4.5 Ga protocrust

    Science.gov (United States)

    Hamilton, Warren B.

    2013-12-01

    This review evaluates and rejects the currently dominant dogmas of geodynamics and geochemistry, which are based on 1950s-1970s assumptions of a slowly differentiating Earth. Evidence is presented for evolution of mantle, crust, and early Moho that began with fractionation of most crustal components, synchronously with planetary accretion, into mafic protocrust by ~ 4.5 Ga. We know little about Hadean crustal geology (> 3.9 Ga) except that felsic rocks were then forming, but analogy with Venus, and dating from the Moon, indicate great shallow disruption by large and small impact structures, including huge fractionated impact-melt constructs, throughout that era. The mantle sample and Archean (preserved Archean crust to its base, and of the thick mafic volcanic rocks erupted on that crust. Lower TTG crust, kept mobile by its high radioactivity and by insulating upper crust, rose diapirically into the upper crust as dense volcanic rocks sagged synformally. The mobile lower crust simultaneously flowed laterally to maintain subhorizontal base and surface, and dragged overlying brittler granite-and-greenstone upper crust. Petrologically required garnet-rich residual protocrust incrementally delaminated, sank through low-density high-mantle magnesian dunite, and progressively re-enriched upper mantle, mostly metasomatically. Archean and earliest Proterozoic craton stabilization and development of final Mohos followed regionally complete early delamination of residual protocrust, variously between ~ 2.9 and 2.2 Ga. Where some protocrust remained, Proterozoic basins, filled thickly by sedimentary and volcanic rocks, developed on Archean crust, beneath which delamination of later residual protocrust continued top-down enrichment of upper mantle. That reenrichment enabled modern-style plate tectonics after ~ 600 Ma, with a transition regime beginning ~ 850 Ma.

  15. Hazy Archean Earth as an Analog for Hazy Earthlike Exoplanets

    Science.gov (United States)

    Arney, Giada; Meadows, Victoria; Domagal-Goldman, Shawn; Claire, Mark; Schwieterman, Edward

    2015-01-01

    Hazy exoplanets may be common (Bean et al. 2010, Sing et al. 2011, Kreidberg et al 2014), and in our solar system, Venus and Titan have photochemically-produced hazes. There is evidence that Earth itself had a hydrocarbon haze in the Archean (Zerkle et al. 2012, Domagal-Goldman et al. 2008) with important climatic effects (Pavlov et al. 2001, Trainer et al. 2006, Haqq-Misra et al. 2008, Wolf and Toon 2012). We use a 1D coupled photochemical-climate model and a line-by-line radiative transfer model to investigate the climactic and spectral impacts of a fractal hydrocarbon haze on Archean Earth. The haze absorbs significantly at shorter wavelengths and can strongly suppress the Rayleigh scattering tail, a broadband effect that would be remotely detectable at low spectral resolution at wavelengths less than 0.5 μm. Hazes may have a more significant impact on transit transmission spectra. Using the transit transmission radiative transfer model developed by Misra et al. (2014) to generate hazy Archean spectra, we find that even a thin hydrocarbon haze masks the lower atmosphere from the visible into the near infrared where the haze optical depth exceeds unity. The transit transmission spectra we generate for hazy Archean Earth are steeply sloped like the Titan solar occultation spectrum observed by Robinson et al. (2014). Thick hazes can also cool the planet significantly: for example, the thick fractal haze generated around Archean Earth with 0.3% CH4, 1% CO2 and 1 ppm C2H6 cools the planet from roughly 290 K without the haze to below freezing with the haze. Finally, we investigate the impact of host star spectral type on haze formation, comparing the hazes generated around a solar-type star to those generated at an Earth analog planet around the M dwarf AD Leo. Our results indicate hazes around M dwarfs for the same initial atmospheric composition may be thinner due to decreased UV photolysis of methane and other hydrocarbons needed for haze formation. Earthlike

  16. Xenon Fractionation and Archean Hydrogen Escape

    Science.gov (United States)

    Zahnle, K. J.

    2015-01-01

    Xenon is the heaviest gas found in significant quantities in natural planetary atmospheres. It would seem the least likely to escape. Yet there is more evidence for xenon escape from Earth than for any element other than helium and perhaps neon. The most straightforward evidence is that most of the radiogenic Xe from the decay of (129)I (half-life 15.7 Myr) and (244)Pu (half-life 81 Myr) that is Earth's birthright is missing. The missing xenon is often attributed to the impact erosion of early atmospheres of Earth and its ancestors. It is obvious that if most of the radiogenic xenon were driven off by impacts, most of the rest of the atmophiles fared the same fate. The other line of evidence is in the nonradiogenic isotopes of xenon and its silent partner, krypton. Atmospheric xenon is strongly mass fractionated (at about 4% per amu) compared to any known solar system source (Figure 1). This is in stark contrast to krypton, which may not be fractionated at all: atmospheric Kr is slightly heavier than solar Kr (at about 0.5% per amu), but it is the same as in carbonaceous chondrites. Nonradiogenic xenon is also under abundant relative to krypton (the so-called "missing xenon" problem). Together these observations imply that xenon has been subject to fractionating escape and krypton not.

  17. Triassic rejuvenation of unexposed Archean-Paleoproterozoic deep crust beneath the western Cathaysia block, South China

    Science.gov (United States)

    Li, Xi-Yao; Zheng, Jian-Ping; Xiong, Qing; Zhou, Xiang; Xiang, Lu

    2018-01-01

    Jurassic (ca. 150 Ma) Daoxian basalts from the western Cathaysia block (South China) entrained a suite of deep-seated crustal xenoliths, including felsic schist, gneiss and granulite, and mafic two-pyroxene granulite and metagabbro. Zircon U-Pb-Hf isotopic, whole-rock elemental and Sr-Nd-Pb isotopic compositions have been determined for these valuable xenoliths to reveal the poorly-known, unexposed deep crust beneath South China. Detrital zircons from the garnet-biotite schists show several populations of ages at 0.65-0.5 Ga, 1.1-0.75 Ga, 1.6-1.4 Ga, 1.8-1.7 Ga, 2.5-2.4 Ga, 2.8 Ga, and 3.5 Ga, representing a multi-sourced, meta-sedimentary origin with deposition time at the early Cambrian. One mafic granulite contains zircons with concordant U-Pb ages of Neoarchean ( 2520 Ma), as well as Hf model ages of 2.8-2.6 Ga and positive εHf(t) values (up to 6.3), suggesting an accretion of juvenile crust in Neoarchean, probably as the main framework of the lower crust. Geochemical and geochronological evidence shows the mafic granulite and metagabbro were produced by underplating of magmas derived from the depleted asthenosphere and mixed with EM2-type materials during the Late Triassic (205-196 Ma). This magmatic underplating also resulted in the widespread metamorphism of the mafic lower crust and felsic middle crust (e.g., the felsic granulite and gneiss) at 202-201 Ma. We suggest the existence of a highly evolved Archean-Paleoproterozoic basement beneath the western Cathaysia block, which experienced episodic accretion and reworking and the strong rejuvenation during the Triassic. A three-layered structure of the lower crust could exist beneath the Daoxian area during the Jurassic time: its upper layer is an evolved Archean-Paleoproterozoic basement; the middle hybrid layer represents a mixture of Archean-Paleoproterozoic basement with newly accreted/reworked Proterozoic to Phanerozoic materials; and the deeper layer consists of mafic granulites derived from the

  18. Sulfur MIF, Organic Haze, and the Gaia Hypothesis in the Archean

    Science.gov (United States)

    Domagal-Goldman, S.; James, K. F.

    2006-05-01

    The presence of mass-independent fractionation (MIF) of sulfur isotopes in Archean sedimentary rocks provides evidence for a low-O2 atmosphere prior to 2.4 Ga. Recent data suggest that S-MIF vanished transiently between ~3.2 Ga and 2.8 Ga. The absence of S-MIF after 2.4 Ga is commonly attributed to the rise of O2 in the atmosphere, as the presence of free O2 would have oxidized all sulfur species, thereby erasing any MIF created by atmospheric photochemistry. However, if free O2 did not appear in the atmosphere until 2.4 Ga, then why did S-MIF disappear transiently much earlier? Could S-MIF have been eliminated from the rock record without the presence of free atmospheric O2? We used a 1-dimensional photochemical model to demonstrate how this might have happened. Increasing the CH4/CO2 ratio in the model atmosphere results in the formation of organic haze. If the haze was sufficiently thick, it would have blocked out much of the solar UV radiation shortward of 220 nm that dissociates SO2 and SO, and thereby causes MIF. The haze should also have caused anti-greenhouse cooling and may have triggered the (putative) 2.8-Ga glaciations. Speculatively, an increase in CH4 at 3.0 Ga could have been caused by the evolution of methanogens, while a CH4 decrease at 2.7 Ga could correspond to the evolution of cyanobacteria. The presence of an optically thin organic haze between 2.4 and 2.7 Ga may explain the larger S-MIF values seen at this time, as compared to the early Archean. If such an organic haze existed, it could have resulted in a biologically-mediated negative feedback loop that stabilized the Archean climate. This feedback loop would have operated as follows: an increase in the biological CH4 flux would have led to an increase in haze thickness and a stronger anti-greenhouse effect, cooling the surface. The surface cooling would have caused a reduction of methanogen productivity, thus offsetting the original increase in the CH4 flux. Such stabilizing feedbacks

  19. Oxidative Weathering of Archean Sulfides: Implications for the Great Oxidation Event

    Science.gov (United States)

    Johnson, A.; Romaniello, S. J.; Reinhard, C.; Garcia-Robledo, E.; Revsbech, N. P.; Canfield, D. E.; Lyons, T. W.; Anbar, A. D.

    2015-12-01

    The first widely accepted evidence for oxidation of Earth's atmosphere and oceans occurs ~2.45 Ga immediately prior to the Great Oxidation Event (GOE). A major line of evidence for this transition includes the abundances and isotopic variations of redox-sensitive transition metals in marine sediments (e.g., Fe, Mo, Re, Cr, and U). It is often assumed that oxidative weathering is required to liberate these redox-sensitive elements from sulfide minerals in the crust, and hence that their presence in early Archean marine sediments signifies that oxidative weathering was stimulated by small and/or transient "whiffs" of O2 in the environment.1 However, studies of crustal sulfide reactivity have not been conducted at O2 concentrations as low as those that would have prevailed when O2 began its rise during the late Archean (estimated at molybdenite oxidation kinetics at the nanomolar O2 concentrations that are relevant to late Archean environments. These measurements were made using recently developed, highly sensitive optical O2 sensors to monitor the rates at which the powdered minerals consumed dissolved O2 in a range of pH-buffered solutions.3Our data extend the range of experimental pyrite oxidation rates in the literature by three orders of magnitude from ~10-3 present atmospheric O2 to ~10-6. We find that molybdenite and pyrite oxidation continues to <1 nM O2 (4 x 10-6 present atmospheric O2). This implies that oxidative weathering of sulfides could occur under conditions which preserve MIF S fractionation. Furthermore, our results indicate that the rate law and reaction order of pyrite oxidation kinetics change significantly at nanomolar concentrations of O2 when compared to previous compilations.2 Our results provide new empirical data that should allow for more precise quantitative constraints on atmospheric pO2 based on the sedimentary rock record. 1Anbar, A.D. et al., 2007. Science, 317, i. 5846: 1903-1906. 2Williamson & Rimstidt, 1994. Geochim. et Cosmochim

  20. Multiple sulfur isotopes monitor fluid evolution of an Archean orogenic gold deposit

    Science.gov (United States)

    LaFlamme, Crystal; Sugiono, Dennis; Thébaud, Nicolas; Caruso, Stefano; Fiorentini, Marco; Selvaraja, Vikraman; Jeon, Heejin; Voute, François; Martin, Laure

    2018-02-01

    The evolution of a gold-bearing hydrothermal fluid from its source to the locus of gold deposition is complex as it experiences rapid changes in thermochemical conditions during ascent through the crust. Although it is well established that orogenic gold deposits are generated during time periods of abundant crustal growth and/or reworking, the source of fluid and the thermochemical processes that control gold precipitation remain poorly understood. In situ analyses of multiple sulfur isotopes offer a new window into the relationship between source reservoirs of Au-bearing fluids and the thermochemical processes that occur along their pathway to the final site of mineralisation. Whereas δ34S is able to track changes in the evolution of the thermodynamic conditions of ore-forming fluids, Δ33S is virtually indelible and can uniquely fingerprint an Archean sedimentary reservoir that has undergone mass independent fractionation of sulfur (MIF-S). We combine these two tracers (δ34S and Δ33S) to characterise a gold-bearing laminated quartz breccia ore zone and its sulfide-bearing alteration halo in the (+6 Moz Au) structurally-controlled Archean Waroonga deposit located in the Eastern Goldfields Superterrane of the Yilgarn Craton, Western Australia. Over 250 analyses of gold-associated sulfides yield a δ34S shift from what is interpreted as an early pre-mineralisation phase, with chalcopyrite-pyrrhotite (δ34S = +0.7‰ to +2.9‰) and arsenopyrite cores (δ34S = ∼-0.5‰), to a syn-mineralisation stage, reflected in Au-bearing arsenopyrite rims (δ34S = -7.6‰ to +1.5‰). This shift coincides with an unchanging Δ33S value (Δ33S = +0.3‰), both temporally throughout the Au-hosting hydrothermal sulfide paragenesis and spatially across the Au ore zone. These results indicate that sulfur is at least partially recycled from MIF-S-bearing Archean sediments. Further, the invariant nature of the observed MIF-S signature demonstrates that sulfur is derived from a

  1. Iron isotopes in ancient and modern komatiites: Evidence in support of an oxidised mantle from Archean to present

    Science.gov (United States)

    Hibbert, K. E. J.; Williams, H. M.; Kerr, A. C.; Puchtel, I. S.

    2012-03-01

    The mantle of the modern Earth is relatively oxidised compared to the initially reducing conditions inferred for core formation. The timing of the oxidation of the mantle is not conclusively resolved but has important implications for the timing of the development of the hydrosphere and atmosphere. In order to examine the timing of this oxidation event, we present iron isotope data from three exceptionally well preserved komatiite localities, Belingwe (2.7 Ga), Vetreny (2.4 Ga) and Gorgona (0.089 Ga). Measurements of Fe isotope compositions of whole-rock samples are complemented by the analysis of olivine, spinel and pyroxene separates. Bulk-rock and olivine Fe isotope compositions (δ57Fe) define clear linear correlations with indicators of magmatic differentiation (Mg#, Cr#). The mean Fe isotope compositions of the 2.7-2.4 Ga and 0.089 Ga samples are statistically distinct and this difference can be explained by greater extent of partial melting represented by the older samples and higher mantle ambient temperatures in the Archean and early Proterozoic relative to the present day. Significantly, samples of all ages define continuous positive linear correlations between bulk rock δ57Fe and V/Sc and δ57Fe and V, and between V/Sc and V with TiO2, providing evidence for the incompatible behaviour of V (relative to Sc) and of isotopically heavy Fe. Partial melting models calculated using partition coefficients for V at oxygen fugacities (fO2s) of 0 and + 1 relative to the fayalite-magnetite-quartz buffer (FMQ) best match the data arrays, which are defined by all samples, from late Archean to Tertiary. These data, therefore, provide evidence for komatiite generation under moderately oxidising conditions since the late Archean, and argue against a change in mantle fO2 concomitant with atmospheric oxygenation at ~ 2.4 Ga.

  2. The electrical lithosphere in Archean cratons: examples from Southern Africa

    Science.gov (United States)

    Khoza, D. T.; Jones, A. G.; Muller, M. R.; Webb, S. J.

    2011-12-01

    The southern African tectonic fabric is made up of a number Archean cratons flanked by Proterozoic and younger mobile belts, all with distinctly different but related geological evolutions. The cratonic margins and some intra-cratonic domain boundaries have played major roles in the tectonics of Africa by focusing ascending magmas and localising cycles of extension and rifting. Of these cratons the southern extent of the Congo craton is one of the least-constrained tectonic boundaries in the African tectonic architecture and knowledge of its geometry and in particular the LAB beneath is crucial for understanding geological process of formation and deformation prevailing in the Archean and later. In this work, which forms a component of the hugely successful Southern African MagnetoTelluric Experiment (SAMTEX), we present the lithospheric electrical resistivity image of the southern boundary of the enigmatic Congo craton and the Neoproterozoic Damara-Ghanzi-Chobe (DGC) orogenic belt on its flanks. Magnetotelluric data were collected along profiles crossing all three of these tectonic blocks. The two dimensional resistivity models resulting from inverting the distortion-corrected responses along the profiles all indicate significant lateral variations in the crust and upper mantle structure along and across strike from the younger DGC orogen to the older adjacent craton. The are significant lithospheric thickness variations from each terrane. The The Moho depth in the DGC is mapped at 40 km by active seismic methods, and is also well constrained by S-wave receiver function models. The Damara belt lithosphere, although generally more conductive and significantly thinner (approximately 150 km) than the adjacent Congo and Kalahari cratons, exhibits upper crustal resistive features interpreted to be caused by igneous intrusions emplaced during the Gondwanan Pan-African magmatic event. The thinned lithosphere is consistent with a 50 mW.m-2 steady-state conductive

  3. Geological and Chemical Factors that Impacted the Biological Utilization of Cobalt in the Archean Eon

    Science.gov (United States)

    Moore, Eli K.; Hao, Jihua; Prabhu, Anirudh; Zhong, Hao; Jelen, Ben I.; Meyer, Mike; Hazen, Robert M.; Falkowski, Paul G.

    2018-03-01

    The geosphere and biosphere coevolved and influenced Earth's biological and mineralogical diversity. Changing redox conditions influenced the availability of different transition metals, which are essential components in the active sites of oxidoreductases, proteins that catalyze electron transfer reactions across the tree of life. Despite its relatively low abundance in the environment, cobalt (Co) is a unique metal in biology due to its importance to a wide range of organisms as the metal center of vitamin B12 (aka cobalamin, Cbl). Cbl is vital to multiple methyltransferase enzymes involved in energetically favorable metabolic pathways. It is unclear how Co availability is linked to mineral evolution and weathering processes. Here we examine important biological functions of Co, as well as chemical and geological factors that may have influenced the utilization of Co early in the evolution of life. Only 66 natural minerals are known to contain Co as an essential element. However, Co is incorporated as a minor element in abundant rock-forming minerals, potentially representing a reliable source of Co as a trace element in marine systems due to weathering processes. We developed a mineral weathering model that indicates that dissolved Co was potentially more bioavailable in the Archean ocean under low S conditions than it is today. Mineral weathering, redox chemistry, Co complexation with nitrogen-containing organics, and hydrothermal environments were crucial in the incorporation of Co in primitive metabolic pathways. These chemical and geological characteristics of Co can inform the biological utilization of other trace metals in early forms of life.

  4. Decoding mass-independent fractionation of sulfur isotopes in modern atmosphere using cosmogenic 35S: A five-isotope approach and possible implications for Archean sulfur isotope records

    Science.gov (United States)

    Lin, M.; Thiemens, M. H.; Shen, Y.; Zhang, X.; Huang, X.; Chen, K.; Zhang, Z.; Tao, J.

    2017-12-01

    The signature of sulfur isotopic mass-independent fractionation (S-MIF) observed in Archean sediments have been interpreted as a proxy of the origins and evolution of atmospheric oxygen and early life on Earth [1]. Photochemistry of SOx in the short (negative Δ36S. After eliminating combustion impacts, the obtained Δ36S/Δ33S slope of -4.0 in the modern atmosphere is close to the Δ36S/Δ33S slope (-3.6) in some records from Paleoarchean [4], an era probably with active volcanism [5]. The significant role of volcanic OCS in the Archean atmosphere has been called for in terms of its ability to provide a continual SO2 high altitude source for photolysis [2]. The strong but previously underappreciated stratospheric signature of S-MIF in tropospheric sulfates suggests that a more careful investigation of wavelength-dependent sulfur isotopic fractionation at different altitudes are required. The combustion-induced negative Δ36S may be linked to recombination reactions of elemental sulfur [6], and relevant experiments are being conducted to test the isotope effect. Although combustion is unlikely in Archean, recombination reactions may occur in other previously unappreciated processes such as volcanism and may contribute in part to the heavily depleted 36S in some Paleoarchean records [5,7]. The roles of both photochemical and non-photochemical reactions in the variability of Archean S-MIF records require further analysis in the future. Refs: [1] Farquhar et al., Science 2000; [2] Shaheen et al., PNAS 2014; [3] Lin et al., PNAS 2016; [4] Wacey et al., Precambrian Res 2015; [5] Muller et al., PNAS 2016; [6] Babikov, PNAS 2017; [7] Shen et al., EPSL, 2009.

  5. Carbon, nitrogen, and sulfur geochemistry of Archean and Proterozoic shales from the Kaapvaal Craton, South Africa

    Science.gov (United States)

    Watanabe, Yumiko; Naraoka, Hiroshi; Wronkiewicz, David J.; Condie, Kent C.; Ohmoto, Hiroshi

    1997-08-01

    1.5 to less than 0.3. Based on the relationships among sulfide-S contents, organic-C contents, and δ 13C org values, four different types of depositional environments are identified for the Archean and early Proterozoic shales in the Kaapvaal Craton: (I) euxinic marine basins, characterized by normal marine organisms with δ 13C org= -33 ± 3%‰ (II) near-shore, oxic marine environment, characterized by normal marine organisms with δ 13C org = -31 ± 3%‰; (III) hypersaline, low-sulfate lakes, characterized by organisms with δ 13C org= -2 ± 3%‰; and (IV) euxinic, marine basins which supported the activity of methanogenic and methanotrophic bacteria and accumulated organic matter with δ 13C org= -43 ± 3%‰. In contrast to the currently popular model positing a global anoxic ocean prior to ˜2.2 Ga (e.g., Des Marais et al, 1992; Hayes, 1994; Logan et al., 1995), this study suggests that the development of anoxic basins, which accumulated Group II and IV sediments, occurred only regionally and episodically during the period between 3.0 Ga and 2.1 Ga. This further suggests that the normal ocean has been oxic since at least ˜3.0 Ga. Diversifications of environments, as well as of biological species, had already occurred ˜3.0 Ga. The carbon isotope mass balance calculation suggests that the removal rates of organic C and carbonate C from the ocean and the weathering rates of organic C and carbonate C on the continents during the 3.0-2.1 Ga period were basically the same as those in the Phanerozoic era. This would have been possible only if the atmospheric P O 2 level had been basically constant since at least 3.0 Ga. The results of this study, therefore, add to a growing list of evidence that the atmosphere has been oxic (i.e., P O 2 > 1%PAL) since at least 3.0 Ga. The list of evidence includes the sulfur isotope data on Archean sedimentary rocks ( Ohmoto and Felder, 1987; Ohmoto et al., 1993), the Fe 3+Ti ratios of paleosols ( Ohmoto, 1996), and the

  6. Alteration of submarine volcanic rocks in oxygenated Archean oceans

    Science.gov (United States)

    Ohmoto, H.; Bevacqua, D.; Watanabe, Y.

    2009-12-01

    Most submarine volcanic rocks, including basalts in diverging plate boundaries and andesites/dacites in converging plate boundaries, have been altered by low-temperature seawater and/or hydrothermal fluids (up to ~400°C) under deep oceans; the hydrothermal fluids evolved from shallow/deep circulations of seawater through the underlying hot igneous rocks. Volcanogenic massive sulfide deposits (VMSDs) and banded iron formations (BIFs) were formed by mixing of submarine hydrothermal fluids with local seawater. Therefore, the behaviors of various elements, especially of redox-sensitive elements, in altered submarine volcanic rocks, VMSDs and BIFs can be used to decipher the chemical evolution of the oceans and atmosphere. We have investigated the mineralogy and geochemistry of >500 samples of basalts from a 260m-long drill core section of Hole #1 of the Archean Biosphere Drilling Project (ABDP #1) in the Pilbara Craton, Western Australia. The core section is comprised of ~160 m thick Marble Bar Chert/Jasper Unit (3.46 Ga) and underlying, inter-bedded, and overlying submarine basalts. Losses/gains of 65 elements were quantitatively evaluated on the basis of their concentration ratios against the least mobile elements (Ti, Zr and Nb). We have recognized that mineralogical and geochemical characteristics of many of these samples are essentially the same as those of hydrothermally-altered modern submarine basalts and also those of altered volcanic rocks that underlie Phanerozoic VMSDs. The similarities include, but are not restricted to: (1) the alteration mineralogy (chlorite ± sericite ± pyrophyllite ± carbonates ± hematite ± pyrite ± rutile); (2) the characteristics of whole-rock δ18O and δ34S values; (3) the ranges of depletion and enrichment of Si, Al, Mg, Ca, K, Na, Fe, Mn, and P; (4) the enrichment of Ba (as sulfate); (5) the increases in Fe3+/Fe2+ ratios; (6) the enrichment of U; (7) the depletion of Cr; and (8) the negative Ce anomalies. Literature data

  7. Deep-Time drilling in the Australian Archean: the Agouron Institute geobiological drilling project. (Invited)

    Science.gov (United States)

    Buick, R.

    2010-12-01

    The Agouron Institute has sponsored deep-time drilling across the South African Archean-Proterozoic boundary, investigating the rise of oxygen over an onshore-offshore environmental transect. It is now supporting a drilling program in the Australian Archean of the Pilbara Craton, addressing a similar theme but with the added goal of resolving controversy over the age and origin of hydrocarbon biomarker molecules in ancient kerogenous shales. As these have been claimed to provide evidence for the evolution of oxygenic photosynthesis long before the rise of atmospheric oxygen to persistently high levels during the ~2.3 Ga “Great Oxidation Event”, their syngenesis with their host shales is thus of critical importance for the interpretation of Earth’s early oxygenation history. During the first drilling season, 3 holes were drilled using techniques and equipment to minimize organic geochemical contamination (new drill-string components cleaned before drilling potentially biomarker-bearing rocks, pre-contamination of drilling fluid with a synthetic organic compound of similar geochemical characteristics to biomarkers, sterile cutting and storage of samples immediately upon retrieval from the core-barrel). The initial hole was a blank control for organic geochemistry, drilled into rocks too metamorphosed to retain biomarker molecules. These rocks, cherts, carbonates and pelites of the 3.52 Ga Coucal Formation, Coonterunah Group, have been metamorphosed to upper greenschist facies at temperatures near 500°C and so should have had any ancient soluble hydrocarbons destroyed. However, because they contain both carbonate and organic carbon, these rocks can instead provide isotopic information about the earliest evolution of biological metabolism as they possess residues of both the reactant and product sides of the carbon-fixation reaction. The second hole sampled an on-shore section of carbonates and kerogenous shales in the ~2.65 Ga Carawine Dolomite and Lewin Shale

  8. Archean Earth Atmosphere Fractal Haze Aggregates: Light Scattering Calculations and the Faint Young Sun Paradox

    Science.gov (United States)

    Boness, D. A.; Terrell-Martinez, B.

    2010-12-01

    As part of an ongoing undergraduate research project of light scattering calculations involving fractal carbonaceous soot aggregates relevant to current anthropogenic and natural sources in Earth's atmosphere, we have read with interest a recent paper [E.T. Wolf and O.B Toon,Science 328, 1266 (2010)] claiming that the Faint Young Sun paradox discussed four decades ago by Carl Sagan and others can be resolved without invoking heavy CO2 concentrations as a greenhouse gas warming the early Earth enough to sustain liquid water and hence allow the origin of life. Wolf and Toon report that a Titan-like Archean Earth haze, with a fractal haze aggregate nature due to nitrogen-methane photochemistry at high altitudes, should block enough UV light to protect the warming greenhouse gas NH3 while allowing enough visible light to reach the surface of the Earth. To test this hypothesis, we have employed a rigorous T-Matrix arbitrary-particle light scattering technique, to avoid the simplifications inherent in Mie-sphere scattering, on haze fractal aggregates at UV and visible wavelenths of incident light. We generate these model aggregates using diffusion-limited cluster aggregation (DLCA) algorithms, which much more closely fit actual haze fractal aggregates than do diffusion-limited aggregation (DLA) algorithms.

  9. Gas bubble dimensions in Archean lava flows indicate low air pressure at 2.7 Ga

    Science.gov (United States)

    Som, S. M.; Buick, R.; Hagadorn, J.; Blake, T.; Perreault, J.; Harnmeijer, J.; Catling, D. C.

    2014-12-01

    Air pressure constrains atmospheric composition, which, in turn, is linked to the Earth system through biogeochemical cycles and fluxes of volatiles from and to the Earth's interior. Previous studies have only placed maximum levels on surface air pressure for the early Earth [1]. Here, we calculate an absolute value for Archean barometric pressure using gas bubble size (vesicle) distributions in uninflated basaltic lava flows that solidified at sea level 2.7 billion years ago in the Pilbara Craton, Western Australia. These vesicles have been filled in by secondary minerals deposited during metasomatism and so are now amydules, but thin sections show that infilling did not change vesicle dimensions. Amygdule dimensions are measured using high-resolution X-ray tomography from core samples obtained from the top and bottom of the lava flows. The modal size expressed at the top and at the bottom of an uninflated flow can be linked to atmospheric pressure using the ideal gas law. Such a technique has been verified as a paleoaltimeter using Hawaiian Quaternary lava flows [2]. We use statistical methods to estimate the mean and standard deviation of the volumetric size of the amygdules by applying 'bootstrap'resampling and the Central Limit Theorem. Our data indicate a surprisingly low atmospheric pressure. Greater nitrogen burial under anaerobic conditions likely explains lower pressure. Refs: [1] Som et al. (2012) Nature 484, 359-262. D. L. Sahagian et al. (2002) J. Geol., 110, 671-685.

  10. Elemental geochemical records of seafloor hydrothermal activities in the sediments from the Okinawa Trough

    Institute of Scientific and Technical Information of China (English)

    ZHAI Shikui; YU Zenghui; DU Tongjun

    2007-01-01

    The major and minor element contents in the sediment core H9 from the hydrothermal fields of the Okinawa Trough show a sharp change at the depth of 80 cm. The elements enriched in the upper 80 cm core are those enriched in the hydrothermal deposits and in the surface sediments recovered from the hydrothermal fields in the trough, which indicates the input of hydrothermal materials. Comparing with other hydrothermal sediments from Mid-ocean Ridges or the Lau Basin, the degree of the enrichment of elements iron, copper, cobalt, and nickel is relatively low. However, the enrichment of elements manganese, lead, arsenic, antimony and mercury is remarkable. The average contents of these elements in the upper 80 cm core sediments are three to six times those in the lower section, and 3 ~ 12 times those in the surface sediments which are not influenced by hydrothermal activities. Hydrothermal activities have contributed significant manganese, lead, arsenic, antimony and mercury to the sediments, and these elements are distinct indicators for the hydrothermal activity in the Okinawa Trough. The significant enrichment of these elements in Core H9 upward from the depth 80 cm indicates the start or the significant enhancing of the hydrothermal activity in this area at about 5 740 aB. P. The average accumulation rate of manganese during this period is about 40 461 μg/( cm2 · ka), which is similar to the hydrothermal sediments in the Lau Basin or the East Pacific Rise.

  11. 182W and HSE constraints from 2.7 Ga komatiites on the heterogeneous nature of the Archean mantle

    Science.gov (United States)

    Puchtel, Igor S.; Blichert-Toft, Janne; Touboul, Mathieu; Walker, Richard J.

    2018-05-01

    While the isotopically heterogeneous nature of the terrestrial mantle has long been established, the origin, scale, and longevity of the heterogeneities for different elements and isotopic systems are still debated. Here, we report Nd, Hf, W, and Os isotopic and highly siderophile element (HSE) abundance data for the Boston Creek komatiitic basalt lava flow (BCF) in the 2.7 Ga Abitibi greenstone belt, Canada. This lava flow is characterized by strong depletions in Al and heavy rare earth elements (REE), enrichments in light REE, and initial ε143Nd = +2.5 ± 0.2 and intial ε176Hf = +4.2 ± 0.9 indicative of derivation from a deep mantle source with time-integrated suprachondritic Sm/Nd and Lu/Hf ratios. The data plot on the terrestrial Nd-Hf array suggesting minimal involvement of early magma ocean processes in the fractionation of lithophile trace elements in the mantle source. This conclusion is supported by a mean μ142Nd = -3.8 ± 2.8 that is unresolvable from terrestrial standards. By contrast, the BCF exhibits a positive 182W anomaly (μ182W = +11.7 ± 4.5), yet is characterized by chondritic initial γ187Os = +0.1 ± 0.3 and low inferred source HSE abundances (35 ± 5% of those estimated for the present-day Bulk Silicate Earth, BSE). Collectively, these characteristics are unique among Archean komatiite systems studied so far. The deficit in the HSE, coupled with the chondritic Os isotopic composition, but a positive 182W anomaly, are best explained by derivation of the parental BCF magma from a mantle domain characterized by a predominance of HSE-deficient, differentiated late accreted material. According to the model presented here, the mantle domain that gave rise to the BCF received only ∼35% of the present-day HSE complement in the BSE before becoming isolated from the rest of the convecting mantle until the time of komatiite emplacement at 2.72 Ga. These new data provide strong evidence for a highly heterogeneous Archean mantle in terms of absolute

  12. Geological Sulfur Isotopes Indicate Elevated OCS in the Archean Atmosphere, Solving the Faint Young Sun Paradox

    DEFF Research Database (Denmark)

    Ueno, Yuichiro; Johnson, Matthew Stanley; Danielache, Sebastian Oscar

    2009-01-01

    Distributions of sulfur isotopes in geological samples would provide a record of atmospheric composition if the mechanism producing the isotope effects could be described quantitatively. We determined the UV absorption spectra of 32SO2, 33SO2, and 34SO2 and use them to interpret the geological re......-rich, reducing Archean atmosphere. The radiative forcing, due to this level of OCS, is able to resolve the faint young sun paradox. Further, the decline of atmospheric OCS may have caused the late Archean glaciation....

  13. Biosphere in 3.5 Ga submarine hydrothermal system

    Energy Technology Data Exchange (ETDEWEB)

    Ueno, Yuichiro [Tokyo Univ. (Japan). Dept. of Earth Science and Astronomy

    2003-04-01

    Abundant organic matter (kerogen) was identified in {approx}3.5 Ga hydrothermal silica dikes from the North Pole area in the Pilbara craton, Western Australia. The silica dikes developed in the uppermost 1000 m of the ancient oceanic crust. Thus, they would have been deposited in the 3.5 Ga sub-seafloor hydrothermal system. The carbon and nitrogen isotopic compositions of the kerogen were analyzed in this study. Their highly {sup 13}C-depleted isotopic compositions ({delta}{sup 13}C = -38 to -33 per mille) strongly suggest that they are originally derived from biologically produced organic matter. The remarkable similarity of the {delta}{sup 13}C values between the kerogen and modern hydrothermal vent organisms may suggest that the kerogen was derived from chemoautotrophic organisms. This idea is also consistent with their nitrogen isotopic compositions ({delta}{sup 15}N = -4 to +4 per mille). The silica dikes consist mainly of fine-grained silica with minor pyrite and sphalerite. These mineral assemblages indicate that the silica dike was deposited from relatively low-temperature (probably less than 150degC) reducing hydrothermal fluid. Thus, anaerobic thermophilic/hyperthermophilic organisms could have survived in the hydrothermal fluid, which formed the silica dikes. Therefore, it is plausible that a chemoautotrophic-based biosphere (possibly methanogenesis) probably existed in the Early Archean sub-seafloor hydrothermal system. (author)

  14. Magmatism and Tectonics in the Meso-Archean Pongola Supergroup, South Africa

    Science.gov (United States)

    Wilson, Allan

    2013-04-01

    vents is a feature of this uniquely preserved magmatic record. New precise zircon U-Pb ages give an indication that the entire basin formed in a remarkably short period of geological time between 2980 ±10 Ma and 2954 ±9 Ma, although complications arising from inherited zircons cannot be ruled out. While komatiites are not present in the Pongola a sequence of volcaniclastic rocks with well-preserved bombs of picrite composition and contained within a sandy matrix gives rise to a geochemical signature high in Cr and Ni which is the first evidence of an ultramafic component to this succession. Evidence of rapid deposition, a preponderance of intermediate lavas, discordance of bounding (earlier) crustal blocks and consistent structural trends in the area, are similar to features found in continental arc basins currently observed in the south-western USA, and may present an alternative model to those currently accepted for Archean terranes in early-formed cratons.

  15. Archean and proterozoic continental crust in South America: Main building events

    International Nuclear Information System (INIS)

    Fuck, R.A; Brito Neves, B.B; Pimentel, M.M

    2001-01-01

    Available geochronological data reveal that the first building blocks of the South American continental crust were set up in the early Paleoarchean, ca. 3.4-3.5 Ga ago, although the presence of components as old as 3.7 Ga is indicated by Nd TDM model ages. The oldest rocks so far recognized are exposed in northeast Brazil and Uruguay. In the Sao Jose do Campestre block, Rio Grande do Norte, 3.45 Ga old tonalite, migmatized and intruded by granitoids between 3.3 and 3.0 Ga, is part of the basement to the Borborema Province (Dantas et al. 1998). In Bahia 3.42 Ga old tonalitic grey gneisses of Sete Voltas, Boa Vista, and Mairi form the basement of the Gaviao block, within the core of the Sao Francisco Craton (Nutman and Cordani, 1993, Martin et al., 1997). The Paleoarchean TTG suites as well as greenstone remnants of unknown age were involved in crust accretion events between 3.1 and 3.3 Ga ago (Teixeira et al. 2000 and references therein), which are also recorded in Campo Belo and Uaua (Teixeira et al., 1998, Oliveira et al., 1999), as attested by TTG intrusions and the ca. 3.1 Ga Pium-hi greenstone belt of W Minas Gerais (Machado and Schrank 1989). Microcontinents then formed were involved in deformation, metamorphism, and migmatization around 2.8-3.0 Ga ago, probably during amalgamation events. Widespread granite-greenstone associations in the Quadrilatero Ferrifero and other areas represent new crust built during the very important Neoarchean Rio das Velhas cycle, ca. 2.7-2.8 Ga ago (Machado and Carneiro 1992, Machado et al. 1992). Layered mafic-ultramafic and granite intrusions ca. 2.5-2.7 Ga old are recorded all over the Sao Francisco Craton, including the high-grade terrain of southern Bahia, formed during the late Archean Jequie Cycle (Teixeira et al. 2000 and references therein). Similar intrusions are recorded in many basement areas within Neoproterozoic fold belts (au)

  16. Stages of material transformations of Archean-Proterozoic rocks (Central-Karelian domain)

    International Nuclear Information System (INIS)

    Vinogradov, V.I.; Buyakajte, M.I.; Kolodyazhnyj, S.Yu.; Leonov, M.G.; Orlov, S.Yu.

    2001-01-01

    The age of the Archean-Proterozoic rocks from the south-east part of the Central-Karelian domain was determined by the method of Rb-Sr dating. It was ascertained that the age of the least tectonized rocks of granite-greenstone Archean foundation makes up 2800±70 mln. years at initial strontium isotopic ratio of 0.7022±0.0007. Gneisses of mainly plagiogranite composition, their age 1930±118 mln. years and strontium isotopic ratio 0.7170±0.0026, constitute the second group of the rocks. It is shown that isotopic age defined for the two groups of rocks agrees well with major geological events on the Baltic shield and planet as a whole [ru

  17. The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth.

    Science.gov (United States)

    Arney, Giada; Domagal-Goldman, Shawn D; Meadows, Victoria S; Wolf, Eric T; Schwieterman, Edward; Charnay, Benjamin; Claire, Mark; Hébrard, Eric; Trainer, Melissa G

    2016-11-01

    Recognizing whether a planet can support life is a primary goal of future exoplanet spectral characterization missions, but past research on habitability assessment has largely ignored the vastly different conditions that have existed in our planet's long habitable history. This study presents simulations of a habitable yet dramatically different phase of Earth's history, when the atmosphere contained a Titan-like, organic-rich haze. Prior work has claimed a haze-rich Archean Earth (3.8-2.5 billion years ago) would be frozen due to the haze's cooling effects. However, no previous studies have self-consistently taken into account climate, photochemistry, and fractal hazes. Here, we demonstrate using coupled climate-photochemical-microphysical simulations that hazes can cool the planet's surface by about 20 K, but habitable conditions with liquid surface water could be maintained with a relatively thick haze layer (τ ∼ 5 at 200 nm) even with the fainter young Sun. We find that optically thicker hazes are self-limiting due to their self-shielding properties, preventing catastrophic cooling of the planet. Hazes may even enhance planetary habitability through UV shielding, reducing surface UV flux by about 97% compared to a haze-free planet and potentially allowing survival of land-based organisms 2.7-2.6 billion years ago. The broad UV absorption signature produced by this haze may be visible across interstellar distances, allowing characterization of similar hazy exoplanets. The haze in Archean Earth's atmosphere was strongly dependent on biologically produced methane, and we propose that hydrocarbon haze may be a novel type of spectral biosignature on planets with substantial levels of CO 2 . Hazy Archean Earth is the most alien world for which we have geochemical constraints on environmental conditions, providing a useful analogue for similar habitable, anoxic exoplanets. Key Words: Haze-Archean Earth-Exoplanets-Spectra-Biosignatures-Planetary habitability

  18. 2.9-1.9 Ga paleoalterations of Archean granitic basement of the Franceville basin (Gabon)

    Science.gov (United States)

    Mouélé, Idalina Moubiya; Dudoignon, Patrick; El Albani, Abderrazak; Meunier, Alain; Boulvais, Philippe; Gauthier-Lafaye, François; Paquette, Jean-Louis; Martin, Hervé; Cuney, Michel

    2014-09-01

    The Archean granitoids in the Kiéné area, Gabon, are overlained by the Paleoproterozoic sediments of the Franceville basin (2.1 Ga). The basin is known for its high-grade uranium deposits among which some have been forming natural nuclear fission reactors. Most of the studies were dedicated to the FA-FB Paleoproterozoic sediments hosting these uranium deposits. Little is known on the Archean basement itself and specifically on the hydrous alteration events it experienced before and after the sediment deposition. The present work is focused on their petrographical, mineralogical and geochemical characterization. Dating the successive alteration events has been attempted on altered monazite crystals. Rocks in different alteration states have been sampled from eight drill cores crosscutting the Archean - Paleoproterozoic unconformity. The Archean granitoids observed in the deepest levels exhibit typical petrographical features of a propylitic alteration while they are intensely illitized up to the unconformity. The propylitic alteration is mainly pervasive but the original texture of the granitoïds is conserved in spite of the formation of new minerals: Mg-chlorite, allanite and epidote forming a typical paragenesis. The illitic alteration is much more invasive near the unconformity. The illitization process leads to the replacement of feldspars and the corrosion of quartz crysals by an illitic matrix while the ferromagnesian minerals are pseudomorphosed by a Fe-chlorite + phengite + hematite assemblage. The final fluid-rock interaction step is marked by fissural deposits of calcite and anhydrite. The δ13C isotopic data show that the fissural carbonates precipitated from diagenetic fluids enriched carbon products deriving from the maturation of organic matter. The U-Pb isotopic analyzes performed on monazite crystals have dated three distinct events: 3.0-2.9 Ga (magmatic), 2.6 Ga (propylitic alteration) and 1.9 Ga (diagenetic illitization). The calculation of

  19. Controls on Atmospheric O2: The Anoxic Archean and the Suboxic Proterozoic

    Science.gov (United States)

    Kasting, J. F.

    2015-12-01

    Geochemists have now reached consensus that the Archean atmosphere was mostly anoxic, that a Great Oxidation Event (GOE) occurred at around 2.5 Ga, and that the ensuing Proterozoic atmosphere was consistently oxidized [1,2]. Evidence for this broad-scale change in atmospheric composition comes from a variety of sources, most importantly from multiple sulfur isotopes [3,4]. The details of both the Archean and Proterozoic environments remain controversial, however, as does the underlying cause of the GOE. Evidence of 'whiffs' of oxygen during the Archean [5] now extend back as far as 3.0 Ga, based on Cr isotopes [6]. This suggests that O2 was being produced by cyanobacteria well before the GOE and that the timing of this event may have been determined by secular changes in O2 sinks. Catling et al. [7] emphasized escape of hydrogen to space, coupled with progressive oxidation of the continents and a concomitant decrease in the flux of reduced gases from metamorphism. But hydrogen produced by serpentinization of seafloor could also have been a controlling factor [8]. Higher mantle temperatures during the Archean should have resulted in thicker, more mafic seafloor and higher H2 production; decreasing mantle temperatures during the Proterozoic should have led to seafloor more like that of today and a corresponding decrease in H2 production, perhaps by enough to trigger the GOE. Once the atmosphere became generally oxidizing, it apparently remained that way during the rest of Earth's history. But O2 levels in the mid-Proterozoic could have been as low at 10-3 times the Present Atmospheric Level (PAL) [9]. The evidence, once again, is based on Cr isotopes. Possible mechanisms for maintaining such a 'suboxic' Proterozoic atmosphere will be discussed. Refs: 1. H. D. Holland, Geochim. Cosmochim. Acta 66, 3811 (2002). 2. H. D. Holland, Philosophical Transactions of the Royal Society B-Biological Sciences 361, 903 (Jun 29, 2006). 3. J. Farquhar, H. Bao, M. Thiemans, Science

  20. An Archean Geomagnetic Reversal in the Kaap Valley Pluton, South Africa

    Science.gov (United States)

    Layer; Kroner; McWilliams

    1996-08-16

    The Kaap Valley pluton in South Africa is a tonalite intrusion associated with the Archean Barberton Greenstone Belt. Antipodal paleomagnetic directions determined from the central and marginal parts of the pluton record a geomagnetic reversal that occurred as the pluton cooled. The age of the reversal is constrained by an 40Ar/39Ar plateau age from hornblende at 3214 +/- 4 million years, making it the oldest known reversal. The data presented here suggest that Earth has had a reversing, perhaps dipolar, magnetic field since at least 3.2 billion years ago.

  1. Late Archean mineralised cyanobacterial mats and their modern analogs

    Science.gov (United States)

    Kazmierczak, J.; Altermann, W.; Kremer, B.; Kempe, S.; Eriksson, P. G.

    2008-09-01

    ,c) reminiscent of common sheaths (glycocalix), typical for coccoidal colonial (pseudoparenchymatous) entophysalidacean or pleurocapsalean cyanobacteria (Fig. 2d-f). The remains of the coccoid sheaths and capsules are visible as a system of rimmed subglobular or irregularly polygonal pits separated from adjacent pits by 2-3 μm thick walls. Microprobe analyses show that the interiors of the pits are composed of almost pure calcium carbonate whereas the rims and walls of calcium carbonate with high admixture of silicates (mostly Al-Fe clay-like silicates) and dolomite. High magnification images of rims and walls confirm the microprobe data indicating authigenic character of the minerals forming both the carbonate infilling the pits interiors (CaCO3) and their rims and walls (CaCO3 + Al-Fe silicates + dolomite). EPSC Abstracts, Vol. 3, EPSC2008-A-00493, 2008 European Planetary Science Congress, Author(s) 2008 It seems that carbonates were the first mineral phase filling the spaces remained after the plasmolysis of the cyanobacterial cell contents, whereas the formation of silicates within the exopolysaccharides forming the bulk of the sheaths and capsules was a later diagenetic process. Microprobe analyses of mineralised modern coccoid cyanobacterial mats forming tower-like structures in the highly alkaline Lake Van, Turkey [3,4] display a set of elements indicative for the presence of authigenic carbonate and silicate minerals which are almost identical with that occurring in the studied Neoarchean samples. Also the optical and SEM images of polished and etched platelets of permineralised Lake Van microbialites are strikingly similar (Fig. 2d-f). Similarly as in modern cyanobacterial and other microbial mats, the process of early post mortem mineralisation, in the case of the Nauga Formation, was most probably associated with the action of heterotrophic bacteria upon the dead cyanobacterial biomass. Heterotrophic bacteria occupying EPS layers of living and dead cyanobacterial

  2. Archean inheritance in zircon from late Paleozoic granites from the Avalon zone of southeastern New England: an African connection

    Science.gov (United States)

    Zartman, R.E.; Don, Hermes O.

    1987-01-01

    In southeastern New England the Narragansett Pier Granite locally intrudes Carboniferous metasedimentary rocks of the Narragansett basin, and yields a monazite UPb Permian emplacement age of 273 ?? 2 Ma. Zircon from the Narragansett Pier Granite contains a minor but detectable amount of an older, inherited component, and shows modern loss of lead. Zircon from the late-stage, aplitic Westerly Granite exhibits a more pronounced lead inheritance -permitting the inherited component to be identified as Late Archean. Such old relict zircon has not been previously recognized in Proterozoic to Paleozoic igneous rocks in New England, and may be restricted to late Paleozoic rocks of the Avalon zone. We suggest that the Archean crustal component reflects an African connection, in which old Archean crust was underplated to the Avalon zone microplate in the late Paleozoic during collision of Gondwanaland with Avalonia. ?? 1987.

  3. Archean Age Fossils from Northwestern Australia (Approximately 3.3 to 3.5 GA, Warrawoona Group, Towers Formation)

    Science.gov (United States)

    Smith, Penny A. Morris

    1999-01-01

    Archean aged rocks from the Pilbara Block area of western Australia (Warrawoona Group, Towers Formation, -3.3-3.5 Ga) contain microfossils that are composed of various sizes of spheres and filaments. The first descriptions of these microfossils were published in the late 1970's (Dunlop, 1978; Dunlop, et. al., 1978). The authenticity of the microfossils is well established. The small size of the microfossils prevents isotope dating, at least with the present technology. Microbiologists, however, have established guidelines to determine the authenticity of the Archean aged organic remains (Schopf, Walter, 1992).

  4. Geochemistry and geochronology of the Archean and palaeo-Proterozoic formations of southern Cameroon (Ntem group, Congo craton)

    International Nuclear Information System (INIS)

    Rchameni, R.

    1997-01-01

    The aim of this work is to understand the crustal evolution of the NW margin of the Congo craton using structural, petrography, isotopic, geochemical and geochronological studies of the Archean and palaeo-Proterozoic formations of the Ntem group of southern Cameroon. The synthesis of these studies allows to propose a diapir-type gravity model linked with the genesis of granitoids to explain the geodynamical evolution of this part of the craton during the Archean. A convergence model with the collision of the Congo and Sao-Francisco cratons and with crust thickening followed by a relaxation phase is proposed for the palaeo-Proterozoic. (J.S.)

  5. A Geological Model for the Evolution of Early Continents (Invited)

    Science.gov (United States)

    Rey, P. F.; Coltice, N.; Flament, N. E.; Thébaud, N.

    2013-12-01

    Geochemical probing of ancient sediments (REE in black shales, strontium composition of carbonates, oxygen isotopes in zircons...) suggests that continents were a late Archean addition at Earth's surface. Yet, geochemical probing of ancient basalts reveals that they were extracted from a mantle depleted of its crustal elements early in the Archean. Considerations on surface geology, the early Earth hypsometry and the rheology and density structure of Archean continents can help solve this paradox. Surface geology: The surface geology of Archean cratons is characterized by thick continental flood basalts (CFBs, including greenstones) emplaced on felsic crusts dominated by Trondhjemite-Tonalite-Granodiorite (TTG) granitoids. This simple geology is peculiar because i/ most CFBs were emplaced below sea level, ii/ after their emplacement, CFBs were deformed into relatively narrow, curviplanar belts (greenstone basins) wrapping around migmatitic TTG domes, and iii/ Archean greenstone belts are richly endowed with gold and other metals deposits. Flat Earth hypothesis: From considerations on early Earth continental geotherm and density structure, Rey and Coltice (2008) propose that, because of the increased ability of the lithosphere to flow laterally, orogenic processes in the Archean produced only subdued topography (Archean CFB were emplaced on flooded continents, Flament et al. (2008) proposed a theory for the hypsometry of the early Earth showing that, until the late Archean, most continents were flooded and Earth was largely a water world. From this, a model consistent with many of the peculiar attributes of Archean geology, can be proposed: 1/ Continents appeared at Earth's surface at an early stage during the Hadean/Archean. However, because they were i/ covered by continental flood basalts, ii/ below sea level, and iii/ deprived of modern-style mountain belts and orogenic plateaux, early felsic

  6. Geochemical Tracers of Processes Affecting the Formation of Seafloor Hydrothermal Fluids and Deposits in the Manus Back-Arc Basin

    Science.gov (United States)

    2009-02-01

    pp. 184-197. Grassle J. F. (1986) The ecology of deep-sea hydrothermal vent communities. Advances in Marine Biology 23, 301-362. Halbach P...Gesellschaft 82, 183-210. Tunnicliffe V. (1991) The biology of hydrothermal vents: Ecology and evolution. Oceanography and Marine Biology Annual Reviews 29...Evidence for Magmatic Contributions to Submarine and Subaerial Gold Mineralization: Conical Seamount and the Ladolam Gold Deposit, Papua New Guinea

  7. Geochemistry of seafloor hydrothermal vent fluids at EPR 9°50'N: Time series data from 2004-2016

    Science.gov (United States)

    Scheuermann, P.; Pester, N. J.; Tutolo, B. M.; Simmons, S. F.; Seyfried, W. E., Jr.

    2017-12-01

    Hydrothermal fluids were collected from vent sites along the East Pacific Rise (EPR) at 9°50'N in 2004, 2008 and 2016 in isobaric gas-tight titanium samplers. These dates bracket the seafloor eruption that occurred at EPR 9°50'N between 2005 and 2006. The reported data focus on P vent and Bio9, as these vents were active during all three sampling periods. The concentration of aqueous volatiles reached maxima at both vents in 2008. At P vent, CO2, H2, and H2S were 124 mM/kg, 0.55 mM/kg and 12.2 mM/kg, respectively. The concentrations at Bio9 in 2008 were, 106 mM/kg CO2, 1.1 mM/kg H2, and 12.6 mM/kg H2S. Fe and Mn concentrations were the highest at both vent sites in 2004, and then decreased in 2008 and again in 2016. The range at P vent was 1.5-6.3 mM/kg Fe and 315-1212 uM/kg Mn, while at Bio9 the concentrations were 1.6-3.7 mM/kg Fe and 301-650 uM/kg Mn. The trends in CO2, H2, and H2S at P vent (2008 and 2016) and Bio9 (all years) are consistent with changes in subsurface pressure and temperature as a result of the eruption that alter the conditions at which dissolved components partition between vapor and liquid phases in the NaCl-H2O system. The trend in Fe and Mn concentrations is surprising and highlights the complex partitioning behavior of these elements in systems in which the concentrations are controlled by fluid-mineral equilibria as well as phase separation. Between 2004 and 2008, fluids at P vent transitioned from single-phase (535 mM/kg Cl) to a low-density vapor (370 mM/kg). Upon phase separation, the concentrations of H2S and H2 increased, while Fe and Mn concentrations decreased considerably. These changes highlight the importance of phase separation on controlling mass transfer from the crust to overlying ocean. In contrast to the other aqueous volatiles, CH4 concentrations in 2008 (47 µM) were lower or equal to concentrations in 2004 or 2016, 50-100 µM. CH4 is decoupled from the effects of phase separation, and is likely extracted from fluid inclusions in the host rock by circulating fluids. Li and CH4 concentrations follow similar patterns over time, supporting a rock-based source for CH4. That CO2 concentrations are elevated (relative to pre-eruption and 2016 values) up to two years after the eruption informs our understanding of the rates of heat and mass transfer in MOR hydrothermal systems.

  8. Evidence for crustal recycling during the Archean: the parental magmas of the stillwater complex

    International Nuclear Information System (INIS)

    McCallum, I.S.

    1988-01-01

    The petrology and geochemistry of the Stillwater Complex, an Archean (2.7 Ga) layered mafic intrusion in the Beartooth Mountains of Montana, is discussed. Efforts to reconstruct the compositions of possible parental magmas and thereby place some constraints on the composition and history of their mantle source regions was studied. A high-Mg andesite or boninite magma best matches the crystallization sequences and mineral compositions of Stillwater cumulates, and represents either a primary magma composition or a secondary magma formed, for example, by assimilation of crustal material by a very Mg-rich melt such as komatiite. Isotopic data do not support the extensive amounts of assimilation required by the komatiite parent hypothesis, and it is argued that the Stillwater magma was generated from a mantle source that had been enriched by recycling and homogenization of older crustal material over a large area

  9. Empirical Records of Environmental Change across the Archean-Proterozoic Transition

    Science.gov (United States)

    Kaufman, A. J.

    2011-12-01

    Time-series geochemical analyses of scientific drill cores intersecting the Archean-Proterozoic transition suggest a coupling of environmental and biological change that culminated in the pervasive oxygenation of Earth's atmosphere and oceans. Elemental and multiple isotope measurements of sedimentary archives, including carbonate, shale, and banded iron-formation from Western Australia, South Africa, Brazil, and southern Canada, indicate important changes in the carbon, sulfur, and nitrogen cycles that monitor the redox state of the oceans and the cyanobacterial buildup of atmospheric oxygen and ozone. In response, continental weathering would have increased, resulting in the enhanced delivery of sulfate and nutrients to seawater, further stimulating photoautotrophic fluxes of oxygen to surface environments. The positive feedback may additionally be responsible for the decline of atmospheric methane and surface refrigeration, represented by a series of discrete ice ages beginning around 2.4 billion years ago, due to the loss of greenhouse capacity during a time of lower solar luminosity. While speculative, the linkage of surface oxidation with enhanced nutrient supply and development of stratospheric sunscreen soon after the Archean-Proterozoic boundary suggests that the earliest perturbation in the carbon cycle may be associated with the rapid expansion of single-celled eukaryotes. Both sterol synthesis in eukaryotes and aerobic respiration require significant levels of oxygen in the ambient environment. Hence, Earth's earliest ice age(s) and onset of a modern and far more energetic carbon cycle may have been directly related to the global expansion of cyanobacteria that released oxygen to the environment, and of eukaryotes that respired it.

  10. Characterizing the Purple Earth: Modeling the globally integrated spectral variability of the Archean Earth

    International Nuclear Information System (INIS)

    Sanromá, E.; Pallé, E.; López, R.; Montañés-Rodríguez, P.; Parenteau, M. N.; Kiang, N. Y.; Gutiérrez-Navarro, A. M.

    2014-01-01

    Ongoing searches for exoplanetary systems have revealed a wealth of planets with diverse physical properties. Planets even smaller than the Earth have already been detected and the efforts of future missions are aimed at the discovery, and perhaps characterization, of small rocky exoplanets within the habitable zone of their stars. Clearly, what we know about our planet will be our guideline for the characterization of such planets. However, the Earth has been inhabited for at least 3.8 Gyr and its appearance has changed with time. Here, we have studied the Earth during the Archean eon, 3.0 Gyr ago. At that time, one of the more widespread life forms on the planet was purple bacteria. These bacteria are photosynthetic microorganisms and can inhabit both aquatic and terrestrial environments. Here, we use a radiative transfer model to simulate the visible and near-infrared radiation reflected by our planet, taking into account several scenarios regarding the possible distribution of purple bacteria over continents and oceans. We find that purple bacteria have a reflectance spectrum that has a strong reflectivity increase, similar to the red edge of leafy plants, although shifted redward. This feature produces a detectable signal in the disk-averaged spectra of our planet, depending on cloud amount and purple bacteria concentration/distribution. We conclude that by using multi-color photometric observations, it is possible to distinguish between an Archean Earth in which purple bacteria inhabit vast extensions of the planet and a present-day Earth with continents covered by deserts, vegetation, or microbial mats.

  11. Awareness for natural radiation potential zones in Archean Terrain of Chhattisgarh State

    International Nuclear Information System (INIS)

    Diwan, H.D.; Pande, S.K.

    2015-01-01

    In the environment, the natural radiations emitted by rocks and soils containing radioactive minerals, largely affected the human being in various aspects. The Chhattisgarh region characterized by the mineral of natural radiations with their relative distribution found in Granitic rocks of Archean age. Adjacent to Cratonic margins, exposures of outer fringes became suitable sites for radiation spread. It constituting towards the emission of radiation by the intrinsic content of minerals present in the host rock i.e. the terrestrial sources of radiation. The Archean terrain covers the surrounding areas of oval cup shaped sedimentary basin and it lies in the S.O.I. toposheet no. 64 G. H.I.K.L. To locate the marked potential zone for natural radiation, the investigation nearby aquatic component of main river and tributaries of Mahanadi river system is important. The presence of Granitic/ Pegmatite rocks at the boundaries of shield areas became promising areas for radiation generating mineral components. Occurrence in the potential zones expressed as lense shaped deposits or strips in dimension of IX1/2 with few hundred long belt. Presence of weathering of Uraninite minerals content remain yellow orange coloured impressions on the surface. In urban areas the background radiation in form of ionic radiation by the residential dwelling units accredates radiations. It needs awareness for Natural Radiation of under zones (NRPZ) in the region. To ensure the effective awareness programme, the area under consideration of natural radiation should take care of socially sustainable activities and spatio-temporal spread to motivate and implement various safety provisions. The model experiments can be sued from R and D point of view, also to alert the people to provide 'Safety, health and welfare of society'. (author)

  12. Chemical and isotopic studies of granitic Archean rocks, Owl Creek Mountains, Wyoming: Geochronology of an Archean granite, Owl Creek Mountains, Wyoming

    International Nuclear Information System (INIS)

    Hedge, C.E.; Simmons, K.R.; Stuckless, J.S.

    1986-01-01

    Rubidium-strontium analyses of whole-rock samples of an Archean granite from the Owl Creek Mountains, Wyo., indicate an intrusive age of 2640 ± 125 Ma. Muscovite-bearing samples give results suggesting that these samples were altered about 2300 Ma. This event may have caused extensive strontium loss from the rocks as potassium feldspar was altered to muscovite. Alteration was highly localized in nature as evidence by unaffected rubidium-strontium mineral ages in the Owl Creek Mountains area. Furthermore, the event probably involved a small volume of fluid relative to the volume of rock because whole-rock δ 18 O values of altered rocks are not distinct from those of unaltered rocks. In contrast to the rubidium-strontium whole-rock system, zircons from the granite have been so severely affected by the alteration event, and possibly by a late-Precambrian uplift event, that the zircon system yields little usable age information. The average initial 87 Sr/ 86 Sr (0.7033 ± 0.0042) calculated from the isochron intercept varies significantly. Calculated initial 87 Sr/ 86 Sr ratios for nine apparently unaltered samples yield a range of 0.7025 to 0.7047. These calculated initial ratios correlate positively with whole-rock δ 18 O values; and, therefore, the granite was probably derived from an isotopically heterogeneous source. The highest initial 87 Sr/ 86 Sr ratio is lower than the lowest reported for the metamorphic rocks intruded by the granite as it would have existed at 2640 Ma. Thus, the metamorphic sequence, at its current level of exposure, can represent no more than a part of the protolith for the granite

  13. A summary of Rb-Sr isotope studies in the Archean Hopedale Block and the adjacent proterozoic Makkovik subprovince, Labrador

    International Nuclear Information System (INIS)

    Grant, N.K.; Hickman, M.H.; Marzano, M.S.; Ermanovics, I.F.

    1983-01-01

    Rb-Sr isotope study of thirteen whole-rock suites of Archean and Proterozoic rocks from Hopedale block and Makkovik Subprovince shows that the crustal history began about 3115 Ma ago. We tentatively recognize younger crustal segments that formed 2920 Ma ago, from which Kanairktok intrusives were derived at 2832 +- 178 Ma. In Makkovik Subprovince the Island Harbour granites range in age from 1843 +- 90 to 1794 +- 71 Ma. These ages overlap with the 1847 +-87 Ma age for Kanairktok shear zone mylonites. The Island Harbour granodiorites from inland localities to the southwest are contaminated with Archean rocks in Makkovik Subprovince and their initial 87 Sr/ 86 ratios imply a crustal contribution to their source. In contrast, the Island Harbour granites of Striped Island were derived from a mantle source. The sills of Striped Island are 1635 +- 47 Ma old. An undeformed northeast trending Kikkertavak dolerite dyke from Hopedale block is 1206 +- 120 Ma

  14. The chemical conditions of the late Archean Hamersley basin inferred from whole rock and pyrite geochemistry with Δ33S and δ34S isotope analyses

    Science.gov (United States)

    Gregory, Daniel D.; Large, Ross R.; Halpin, Jacqueline A.; Steadman, Jeffery A.; Hickman, Arthur H.; Ireland, Trevor R.; Holden, Peter

    2015-01-01

    The well-preserved late Archean sedimentary rocks of the Fortescue and Hamersley Basins in Western Australia offer fascinating insights into early earth ocean chemistry prior to the Great Oxidation Event (GOE). In this study, we use a combination of whole rock geochemistry, LA-ICPMS trace element analysis of sedimentary pyrite and pyrrhotite and SHRIMP-SI sulfur isotope analyses to elucidate the chemical changes in these sedimentary rocks. These proxies are used to examine chemical conditions of the ocean during the late Archean. Two to three periods of oxygen enrichment prior to the deposition of banded iron formations (BIF) can be identified. One minor stage of general increase in whole rock enrichment factors and trace element content of pyrite is observed up stratigraphy in the Jeerinah Formation, Fortescue Basin and a more substantial stage is present in the Paraburdoo and Bee Gorge Members of the Wittenoom Formation, Hamersley Basin. Some of the trace element enrichments indicate organic matter burial flux (Ni, Cr, Zn, Co and Cu) which suggests an increase in biological productivity. If the increased biological activity reflects an increase in cyanobacteria activity then an associated increase in oxygen is likely to have occurred during the deposition of the Bee Gorge Member. An increase in atmospheric oxygen would result in continental weathering of sulfide and other minerals, increasing the trace element content of the water column via erosion and avoiding excessive depletion of trace elements due to drawdown in seawater. Since some of these trace elements may also be limiting nutrients (such as Mo and Se) for the cyanobacteria, the degree of biological productivity may have further increased due to the increasing amount of trace elements introduced by oxygenation in a positive feedback loop. These periods of increased productivity and oxygen rise stopped prior to the onset of BIF deposition in the Hamersley Basin. This may be due to the ocean reaching an

  15. Coexistence of enriched and modern-like 142Nd signatures in Archean igneous rocks of the eastern Kaapvaal Craton, southern Africa

    Science.gov (United States)

    Schneider, Kathrin P.; Hoffmann, J. Elis; Boyet, Maud; Münker, Carsten; Kröner, Alfred

    2018-04-01

    The short-lived 146Sm-142Nd isotope system is an important tool for tracing Hadean crust-mantle differentiation processes and constraining their imprint on much younger rocks from Archean cratons. We report the first comprehensive set of high-precision 142Nd analyses for granitoids and amphibolites of the Ancient Gneiss Complex (AGC; Swaziland) and the oldest metavolcanic units of the Barberton Greenstone Belt (BGB; South Africa). The investigated samples span an age range from 3.66 Ga to 3.22 Ga and are representative of major geological units of the AGC and the lower Onverwacht Group of the BGB. Measured samples yielded μ142Nd values in the range from -8 ppm to +3 ppm relative to the JNdi-1 terrestrial standard, with typical errors smaller than 4.4 ppm. The distribution of the μ142Nd values for these 17 measured samples is bimodal with ten samples showing a tendency towards slightly negative μ142Nd anomalies, whereas seven samples have 142Nd similar to the terrestrial reference. The only confidently resolvable μ142Nd anomalies were found in a 3.44 Ga Ngwane Gneiss sample and in amphibolites of the ca. 3.45 Ga Dwalile Greenstone Remnant, revealing μ142Nd values ranging from - 7.9 ± 4.4 to - 6.1 ± 4.3 ppm. The μ142Nd deficits do not correlate with age, lithological unit, or sample locality. Instead, our results reveal that two distinct mantle domains were involved in the formation of the AGC crust. The two reservoirs can be distinguished by their μ142Nd signatures. Mantle-derived rocks tapped the enriched reservoir with negative μ142Nd at least until 3.46 Ga, whereas the granitoids preserved a negative μ142Nd signature that formed by incorporation of older AGC crust at least until 3.22 Ga. The oldest gneisses with no μ142Nd anomaly are up to 3.64 Ga in age, indicating that a modern terrestrial 142Nd reservoir was already present by early Archean times.

  16. Molybdenum isotopes in modern marine hydrothermal Fe/Mn deposits: Implications for Archean and Paleoproterozoic Mo cycles

    Science.gov (United States)

    Goto, K. T.; Hein, J. R.; Shimoda, G.; Aoki, S.; Ishikawa, A.; Suzuki, K.; Gordon, G. W.; Anbar, A. D.

    2016-12-01

    Molybdenum isotope (δ98/95Mo) variations recorded in Archean and Paleoproterozoic Fe/Mn-rich sediments have been used to constrain ocean redox conditions at the time of deposition (Canfield et al., 2013 PNAS; Planavsky et al., 2014 Nat. Geo.; Kurzweil et al., 2015 GCA). However, except for hydrogenous Fe-Mn crusts (Siebert et al., 2003), δ98/95Mo variation of modern Fe and Mn oxide deposits has been poorly investigated. Marine hydrothermal systems are thought to be the major source of Fe and Mn in Archean and Paleoproterozoic Fe- and Mn-rich sediments. Hence, to accurately interpret Mo isotope data of those ancient sedimentary rocks, it is important to evaluate the possible influence of hydrothermally derived Mo on δ98/95Mo of modern Fe- and Mn-rich sediments. In this study, we analyzed Mo isotopic compositions of one hydrothermal Fe oxide and 15 Mn oxides from five different hydrothermal systems in the modern ocean. The Fe oxide is composed mainly of goethite, and has a δ98/95Mo of 0.7‰, which is 1.4‰ lighter than that of present-day seawater. The observed offset is similar to isotope fractionation observed during adsorption experiments of Mo on goethite (Δ98/95Mogoethite-solution = -1.4 ± 0.5%; Goldberg et al., 2009 GCA). The 15 hydrothermal Mn oxides show large variations in δ98/95Mo ranging from -1.7 to 0.5‰. However, most of the values are similar to those of modern hydrogenous Fe-Mn crusts (Siebert et al., 2003 EPSL), and fall within the range of estimated δ98/95Mo of Mn oxides precipitated from present-day seawater using the isotope offset reported from adsorption experiments (Δ98/95Mo = -2.7 ± 0.3‰; Wasylenki et al., 2008 GCA). These findings indicate that seawater is the dominant source of Mo for modern hydrothermal Fe and Mn deposits. However, the observed large variation indicates that the contribution Mo from local hydrothermal systems is not negligible. The oceanic Mo inventory during the Archean and Paleoproterozoic is thought to be

  17. U enrichment and Th/U fractionation in Archean boninites: Implications for paleo-ocean oxygenation and U cycling at juvenile subduction zones

    Science.gov (United States)

    Manikyamba, C.; Said, Nuru; Santosh, M.; Saha, Abhishek; Ganguly, Sohini; Subramanyam, K. S. V.

    2018-05-01

    Phanerozoic boninites record enrichments of U over Th, giving Th/U: 0.5-1.6, relative to intraoceanic island arc tholeiites (IAT) where Th/U averages 2.6. Uranium enrichment is attributed to incorporation of shallow, oxidized fluids, U-rich but Th-poor, from the slab into the melt column of boninites which form in near-trench to forearc settings of suprasubduction zone ophiolites. Well preserved Archean komatiite-tholeiite, plume-derived, oceanic volcanic sequences have primary magmatic Th/U ratios of 4.4-3.6, and Archean convergent margin IAT volcanic sequences, having REE and HFSE compositions similar to Phanerozoic IAT equivalents, preserve primary Th/U of 4-3.6. The best preserved Archean boninites of the 3.0 Ga Olondo and 2.7 Ga Gadwal greenstone belts, hosted in convergent margin ophiolite sequences, also show relative enrichments of U over Th, with low average Th/U ∼3 relative to coeval IAT, and Phanerozoic counterparts which are devoid of crustal contamination and therefore erupted in an intraoceanic setting, with minimal contemporaneous submarine hydrothermal alteration. Later enrichment of U is unlikely as Th-U-Nb-LREE patterns are coherent in these boninites whereas secondary effects induce dispersion of Th/U ratios. The variation in Th/U ratios from Archean to Phanerozoic boninites of greenstone belts to ophiolitic sequences reflect on genesis of boninitic lavas at different tectono-thermal regimes. Consequently, if the explanation for U enrichment in Phanerozoic boninites also applies to Archean examples, the implication is that U was soluble in oxygenated Archean marine water up to 600 Ma before the proposed great oxygenation event (GOE) at ∼2.4 Ga. This interpretation is consistent with large Ce anomalies in some hydrothermally altered Archean volcanic sequences aged 3.0-2.7 Ga.

  18. Generation of TTG rocks in the Archean: insight from numerical simulations

    Science.gov (United States)

    Rozel, Antoine; Golabek, Gregor; Gerya, Taras; Jain, Charitra; Tackley, Paul

    2017-04-01

    We study the creation of primordial continental crust (TTG rocks) for the first time employing fully self-consistent numerical models of thermochemical convection on a global scale. Starting from a pyrolytic bulk composition and an initially hot core, we first generate oceanic crust and depleted mantle. In our model, the basaltic material is both erupted at the surface and intruded at the base of the crust following a predefined partitioning. Second, we track the pressure-temperature conditions of the newly formed hydrated basalt and check if it matches the conditions necessary for the formation of primordial continental crust. We show that the "heat-pipe" model (assuming 100% eruption and no intrusion) proposed to be the main heat loss mechanism during the Archean epoch (Moore & Webb 2013) is not able to produce continental crust since it forms a cold and thick lithosphere. We systematically test various mechanical properties of the brittle domain (friction coefficients). Using our parameter study, we are also able to show that an intrusion fraction close to 70% (in agreement with [Crisp 1984]) combined with a friction coefficient of 0.2 products the expected amount of the three main petrological TTG compositions previously reported (Moyen 2011). This study represents a major step towards the production of self-consistent convection models able to generate the continental crust of the Earth. REFERENCES Crisp, J. A. (1984), Rates of magma emplacement and volcanic output. Journal of Volcanology and Geothermal Research, 20(3-4), 177-211. Moore, W., and A. Webb (2013), Heat-pipe earth. Nature, 501, 501-505, doi:10.1038/nature12473. Moyen, J. (2011), The composite archaean grey gneisses: Petrological significance, and evidence for a non-unique tectonic setting for archaean crustal growth. Lithos, 123, 21-36, doi: 10.1016/j.lithos.2010.09.015.

  19. The Importance of Transition Metals in the Expanding Network of Microbial Metabolism in the Archean Eon

    Science.gov (United States)

    Moore, E. K.; Jelen, B. I.; Giovannelli, D.; Prabhu, A.; Raanan, H.; Falkowski, P. G.

    2017-12-01

    Deep time changes in Earth surface redox conditions, particularly due to global oxygenation, has impacted the availability of different metals and substrates that are central in biology. Oxidoreductase proteins are molecular nanomachines responsible for all biological electron transfer processes across the tree of life. These enzymes largely contain transition metals in their active sites. Microbial metabolic pathways form a global network of electron transfer, which expanded throughout the Archean eon. Older metabolisms (sulfur reduction, methanogenesis, anoxygenic photosynthesis) accessed negative redox potentials, while later evolving metabolisms (oxygenic photosynthesis, nitrification/denitrification, aerobic respiration) accessed positive redox potentials. The incorporation of different transition metals facilitated biological innovation and the expansion of the network of microbial metabolism. Network analysis was used to examine the connections between microbial taxa, metabolic pathways, crucial metallocofactors, and substrates in deep time by incorporating biosignatures preserved in the geologic record. Nitrogen fixation and aerobic respiration have the highest level of betweenness among metabolisms in the network, indicating that the oldest metabolisms are not the most central. Fe has by far the highest betweenness among metals. Clustering analysis largely separates High Metal Bacteria (HMB), Low Metal Bacteria (LMB), and Archaea showing that simple un-weighted links between taxa, metabolism, and metals have phylogenetic relevance. On average HMB have the highest betweenness among taxa, followed by Archaea and LMB. There is a correlation between the number of metallocofactors and metabolic pathways in representative bacterial taxa, but Archaea do not follow this trend. In many cases older and more recently evolved metabolisms were clustered together supporting previous findings that proliferation of metabolic pathways is not necessarily chronological.

  20. The extant shore platform stromatolite (SPS facies association: a glimpse into the Archean?

    Directory of Open Access Journals (Sweden)

    A. Smith

    2018-04-01

    Full Text Available Shore platform stromatolites (SPS were first noted at Cape Morgan on the south-east African seaboard. Since then they have been found growing discontinuously in rocky peritidal zones along the entire southern African seaboard. They have also been found on the southwest Australian coast, at Giant's Causeway in Northern Ireland, and more recently at Harris on the Scottish Hebridean Atlantic coast. In this paper SPS occurrence and SPS potential as analogues for Precambrian fossil stromatolites, as well as potential stromatolite occurrences in shore platform regions on Mars, are assessed. Sub-horizontal surfaces promote stromatolite development, while tufa develops on cliffs and steep rocky surfaces. Tufa and stromatolites are end members of a spectrum dictated by coastal topography. Extant SPS occur on well indurated shore platforms in high wave energy settings, often around or near headlands. They can be associated with boulder beaches, boulder ridges, storm swash terraces, coastal dunes, and peat bogs. In contrast to other extant stromatolites, SPS are produced primarily by mineral precipitation, although minor trapping and binding stromatolites do occur. From a geological perspective, SPS develop in mildly transgressive siliciclastic settings in various climatic and tidal regimes. We suggest that SPS could be preserved in the geological record as micritic lenses on palaeo-shore platform surfaces. SPS share many features with Precambrian stromatolites and are a valid modern analogue despite the widely different atmospheric and oceanic conditions of the Archean. We suggest that terraces associated with former oceanic or lacustrine flooding surfaces on Mars are potential targets in the search for palaeo-SPS on Mars.

  1. Reactions between olivine and CO2-rich seawater at 300 °C: Implications for H2 generation and CO2 sequestration on the early Earth

    Directory of Open Access Journals (Sweden)

    Hisahiro Ueda

    2017-03-01

    Full Text Available To understand the influence of fluid CO2 on ultramafic rock-hosted seafloor hydrothermal systems on the early Earth, we monitored the reaction between San Carlos olivine and a CO2-rich NaCl fluid at 300 °C and 500 bars. During the experiments, the total carbonic acid concentration (ΣCO2 in the fluid decreased from approximately 65 to 9 mmol/kg. Carbonate minerals, magnesite, and subordinate amount of dolomite were formed via the water-rock interaction. The H2 concentration in the fluid reached approximately 39 mmol/kg within 2736 h, which is relatively lower than the concentration generated by the reaction between olivine and a CO2-free NaCl solution at the same temperature. As seen in previous hydrothermal experiments using komatiite, ferrous iron incorporation into Mg-bearing carbonate minerals likely limited iron oxidation in the fluids and the resulting H2 generation during the olivine alteration. Considering carbonate mineralogy over the temperature range of natural hydrothermal fields, H2 generation is likely suppressed at temperatures below approximately 300 °C due to the formation of the Mg-bearing carbonates. Nevertheless, H2 concentration in fluid at 300 °C could be still high due to the temperature dependency of magnetite stability in ultramafic systems. Moreover, the Mg-bearing carbonates may play a key role in the ocean-atmosphere system on the early Earth. Recent studies suggest that the subduction of carbonated ultramafic rocks may transport surface CO2 species into the deep mantle. This process may have reduced the huge initial amount of CO2 on the surface of the early Earth. Our approximate calculations demonstrate that the subduction of the Mg-bearing carbonates formed in komatiite likely played a crucial role as one of the CO2 carriers from the surface to the deep mantle, even in hot subduction zones.

  2. Single-zircon dating by stepwise Pb-evaporation constrains the Archean history of detrital zircons from the Jack Hills, Western Australia

    International Nuclear Information System (INIS)

    Kober, B.; Lippolt, H.J.; Pidgeon, R.T.

    1989-01-01

    Pb isotope analyses have been carried out on 42 zircon grains from a Western Australian metaconglomerate using stepwise Pb-evaporation directly in the ion source of a thermal ionization mass spectrometer. The metaconglomerate is from the Archean Jack Hills Metasedimentary Belt, and is known from ion microprobe (''SHRIMP'') analyses to contain a complex zircon population with ages between 4.2 Ga and 3.1 Ga. The same complex pattern of ages is found by the Pb evaporation studies. Five grains yielded minimum crystallization ages from 4.17 Ga to 4.07 Ga. The main population appears significantly younger, having been generated at about 3.55-3.3 Ga. The agreement between the two analytical approaches confirms the SHRIMP results and demonstrates the value of the stepwise-evaporation technique in determining the age patterns of mixing zircon populations. In many of the evaporative Pb isotope records the 207/206 ratios remained constant for all evaporation steps, which we interpret as evaporation from concordant zircon phases. However, for the majority of zircons 207/206 ratios increased with increasing evaporation temperature, and usually approached constant values during evaporation at the highest temperatures. This can be attributed to mixing of different radiogenic Pb components from either crystalline zircon phases of different ages or from domains of isotopically disturbed metamict zircon. Present results confirm > 4 Ga zircon ages in the metaconglomerate from the Hack Hills and substantiate formation of crust at a very early stage in the evolution of the earth. Results also confirm a major crust-forming event 3.55-3.3 Ga ago. (orig.)

  3. Formation of the Archean crust of the ancient Vodlozero domain (Baltic shield)

    Science.gov (United States)

    Arestova, N. A.; Chekulaev, V. P.; Lobach-Zhuchenko, S. B.; Kucherovskii, G. A.

    2015-03-01

    The available geological, petrological, and isotopic data on Archean rocks of the Baltic shield are used to analyze the formation of the crust of the ancient Vodlozero domain. This made it possible to reveal the succession of endogenic processes in different parts of the domain and correlate them between each other. Several stages of magmatic processes reflecting changes in magma-generation environments are definable in the crust formation. The earliest stages of magmatism (3.24 and 3.13-3.15 Ga) are mostly represented by rocks of the tonalite-trondhjemite-granodiorite association. The next stage of endogenic activity (3020-2900 Ma) was marked by the formation of volcanics of the komatiite-basalt and andesite-dacite associations constituting greenstone belts in marginal parts of the Vodlozero domain and basic dikes accompanied by layered pyroxenite-norite-diorite intrusion in its central part. These basic bodies crossing earlier tonalities were formed in extension settings related to the formation of the mantle plume, which is confirmed by the rock composition. This stage culminated in the formation of trondhjemites at margins of greenstone structure. The next stage of endogenic activity commenced at 2890-2840 Ma by the emplacement of high-magnesian gabbro and diorite dikes in the western margin of the domain, where they cross rocks of the tonalitetrondhjemite association. This stage was marked by the formation of intermediate-acid subvolcanic bodies and dikes as well as basite intrusions including the layered and differentiated Semch intrusion, the largest one in the Vodlozero domain. The stage culminated at approximately 2850 Ma in the emplacement of tonalities of the limited distribution being represented by the Shilos massif in the north of the domain and Shal'skii massif on the eastern shore of Lake Onega. The important stage in the geological history of the Vodlozero domain is the formation of the intracratonic Matkalakhta greenstone belt at approximately 2

  4. 40Ar/39Ar incremental-release ages of biotite from a progressively remetamorphosed Archean basement terrane in southwestern Labrador

    International Nuclear Information System (INIS)

    Dallmeyer, R.D.

    1982-01-01

    Gneisses within Archean basement terrane adjacent to the southwestern portion of the Labrador Trough were variably retrograded during a regional metamorphism of Grenville age (ca. 1000 Ma). Bioties from non-retrograded segments of the gneiss terrane record 40 Ar/ 39 Ar plateau and isochron ages which date times of cooling following an episode of the Kenoran orogeny (2376-2391 Ma). A suite of gneiss samples displaying varying degrees of retrograde alteration was collected across the Grenville metamorphic gradient. Bioties in these samples show no petrographic evidence of retrograde alteration, however they do record internally discordant 40 Ar/ 39 Ar age spectra. Although the extent of internal discordance is variable, the overall character of the release patterns is similar with younger apparent ages recorded in intermediate-temperature gas fractions. The total-gas dates range from 2257+-27 Ma (northwest) to 1751+-23 Ma (southeast), suggesting that variable quantities of radiogenic argon were lost from the Archean biotites during Grenville metamorphism. The 'saddle-shaped' nature of the discordant spectra indicates that argon loss was not accomplished through single-stage, volume diffusion processes. (orig./ME)

  5. Controversial Pb-Pb and Sm-Nd isotope results in the early Archean Isua (West Greenland) oxide iron formation

    DEFF Research Database (Denmark)

    Frei, Robert; Rosing, Minik; Stecher, Ole

    1999-01-01

    Pb stepwise leaching (PbSL) determinations on two magnetite-enriched fractions of a BIF sample from the northeastern part of the Isua supracrustal belt (West Greenland) yield an isochron of 3691 ± 22 Ma (MSWD = 0.4). In combination with previously published geochronological constraints for a mini...

  6. SHRIMP-RG U-Pb isotopic systematics of zircon from the Angel Lake orthogneiss, East Humboldt Range, Nevada: Is this really archean crust?

    Science.gov (United States)

    Premo, Wayne R.; Castineiras, Pedro; Wooden, Joseph L.

    2008-01-01

    New SHRIMP-RG (sensitive high-resolution ion microprobe-reverse geometry) data confirm the existence of Archean components within zircon grains of a sample from the orthogneiss of Angel Lake, Nevada, United States, previously interpreted as a nappe of Archean crust. However, the combined evidence strongly suggests that this orthogneiss is a highly deformed, Late Cretaceous monzogranite derived from melting of a sedimentary source dominated by Archean detritus. Zircon grains from the same sample used previously for isotope dilution-thermal ionization mass spectrometry (ID-TIMS) isotopic work were analyzed using the SHRIMP-RG to better define the age and origin of the orthogneiss. Prior to analysis, imaging revealed a morphological variability and intragrain, polyphase nature of the zircon population. The SHRIMP-RG yielded 207Pb/206Pb ages between ca. 2430 and 2580 Ma (a best-fit mean 207Pb/206Pb age of 2531 ± 19 Ma; 95% confidence) from mostly rounded to subrounded zircons and zircon components (cores). In addition, several analyses from rounded to subrounded cores or grains yielded discordant 207Pb/206Pb ages between ca. 1460 and ca. 2170 Ma, consistent with known regional magmatic events. All cores of Proterozoic to latest Archean age were encased within clear, typically low Th/U (206Pb/238U ages between 72 and 91 Ma, consistent with magmatic ages from Lamoille Canyon to the south. An age of ca. 90 Ma is suggested, the younger 206Pb/238U ages resulting from Pb loss. The Cretaceous and Precambrian zircon components also have distinct trace element characteristics, indicating that these age groups are not related to the same igneous source. These results support recent geophysical interpretations and negate the contention that the Archean-Proterozoic boundary extends into the central Great Basin area. They further suggest that the world-class gold deposits along the Carlin Trend are not underlain by Archean cratonal crust, but rather by the Proterozoic Mojave

  7. Cyclic formation and stabilization of Archean lithosphere by accretionary orogenesis: Constraints from TTG and potassic granitoids, North China Craton

    Science.gov (United States)

    Wang, Wei; Cawood, Peter A.; Liu, Shuwen; Guo, Rongrong; Bai, Xiang; Wang, Kang

    2017-09-01

    Accretionary orogens are major sites of modern continental growth, yet their role in the development of Archean continental crust remains enigmatic. Diverse granitoid suites from tonalite-trondhjemite-granodiorite (TTG) to potassic granitoids appeared during late Archean, representing a period of major continental formation and stabilization. In this study, whole-rock geochemical and zircon U-Pb and Lu-Hf isotopic data are reported for Neoarchean granitoid gneisses from the Northern Liaoning Terrane, northeastern North China Craton (NCC). Older granitoid gneisses ( 2592-2537 Ma) define three magmatic zones migrating from southeast to northwest, each showing a common magmatic evolution from high-pressure TTGs to medium-/low-pressure TTGs and potassic granitoids. They have depleted zircon ƐHf(t) of +0.5 to +8.7. Younger 2529-2503 Ma potassic granitoids and TTGs occur throughout the terrane, which are marked by variable zircon ƐHf(t) of -4.7 to +8.1, and are coeval with regional high-grade metamorphism. Petrogenetic modeling and changing Sr/Y and (La/Yb)N of the granitoids suggest that the crust experienced episodic thickening and thinning and became progressively evolved through development of potassic granitoids and sedimentary successions. The metavolcanic basement to the granitoids display tholeiitic to calc-alkaline affinities, together with the top-to-the-northwest thrusting and associated volcanogenic massive sulfide-type Cu-Zn deposits, suggesting cyclic crustal formation of Northern Liaoning within an accretionary orogen with a SE-dipping subduction polarity. Cyclic crustal thickening and thinning is related to tectonic switching from advancing to retreating relations between the downgoing and overriding plate. After 2530 Ma, this accretionary system accreted to the ancient continental nucleus of NCC (Anshan-Benxi Terrane), signifying final lithosphere stabilization.

  8. Updating the Geologic Barcodes for South China: Discovery of Late Archean Banded Iron Formations in the Yangtze Craton.

    Science.gov (United States)

    Ye, Hui; Wu, Chang-Zhi; Yang, Tao; Santosh, M; Yao, Xi-Zhu; Gao, Bing-Fei; Wang, Xiao-Lei; Li, Weiqiang

    2017-11-08

    Banded iron formations (BIFs) in Archean cratons provide important "geologic barcodes" for the global correlation of Precambrian sedimentary records. Here we report the first finding of late Archean BIFs from the Yangtze Craton, one of largest Precambrian blocks in East Asia with an evolutionary history of over 3.3 Ga. The Yingshan iron deposit at the northeastern margin of the Yangtze Craton, displays typical features of BIF, including: (i) alternating Si-rich and Fe-rich bands at sub-mm to meter scales; (ii) high SiO 2  + Fe 2 O 3total contents (average 90.6 wt.%) and Fe/Ti ratios (average 489); (iii) relative enrichment of heavy rare earth elements and positive Eu anomalies (average 1.42); (iv) and sedimentary Fe isotope compositions (δ 56 Fe IRMM-014 as low as -0.36‰). The depositional age of the BIF is constrained at ~2464 ± 24 Ma based on U-Pb dating of zircon grains from a migmatite sample of a volcanic protolith that conformably overlied the Yingshan BIF. The BIF was intruded by Neoproterozoic (805.9 ± 4.7 Ma) granitoids that are unique in the Yangtze Craton but absent in the North China Craton to the north. The discovery of the Yingshan BIF provides new constraints for the tectonic evolution of the Yangtze Craton and has important implications in the reconstruction of Pre-Nuna/Columbia supercontinent configurations.

  9. Pb-Pb and U-Pb zircon ages of archean syntetocnic granites of the Carajas metallogenic province, northern Brazil

    International Nuclear Information System (INIS)

    Barros, Carlos Eduardo de Mesquita; Sardinha, Alex Souza; Barbosa, Jaime dos Passos de Oliveira; Krimski, Robert; Macambira, Moacir Jose Buenano

    2001-01-01

    The Carajas Metallogenic Province is located in the southeastern Amazonian Craton. It has been divided in two domains, the southernmost comprises the Rio Maria region and the northernmost corresponds to Caraj region (Souza et al. 1996). The former domain is made up of Archean greenstone sequences (2,97 Ga), TTG (2,9 Ga) and calc-alkaline granitoids (2,87 Ga) (Macambira and Lafon 1995, Leite et al. 1999, Althoff et al. 2000). The Carajas block is constituted of minor mafic granulites (3,00 Ga) and quartzofeldspathic gneisses (2,81 Ga), metavolcanosedimentary sequences (2,76 Ga) and granites (2,76 to 2,56 Ga) (Machado et al. 1991; Huhn et al. 1999, Pidgeon et al. 2000). Widespread anorogenic A-type granites are found in both areas (Docegeo 1988; Dall'Agnol et al. 1994). In the last two decades several authors (Lindenamyer et al. 1994, Barros and Barbey 1998, Huhn et al. 1999 and others) have emphasized the role of the Archean granite magmatism in the tectonicthermal evolution in the Carajas Province. In this paper we discuss the tectonic significance of the Pb- Pb and U-Pb ages obtained in some granitoids from the Carajas region. The Estrela Granite Complex and the granitoids located to the north of Parauapebas were dated by Pb- Pb evaporation zircon method (cf. Kober 1987). Data are presented considering 2σ ∼ . The Pb corrections have been done in the basis of the evolution model of Pb in double stage (cf. Stacey and Kramers 1975). U-Pb zircon method (cf. Krogh 1973, Stacey and Kramers 1975, Parrish 1987, Ludwuig 1999), recently put on routine in the Para-Iso laboratories, was employed to date the granite from the Serra do Rabo area. Analyses were carried on the Finnigan Mat 262 spectrometer (au)

  10. SHRIMP-RG U-Pb isotopic systematics of zircon from the Angel Lake orthogneiss, East Humboldt Range, Nevada: is this really Archean crust? REPLY

    Science.gov (United States)

    Premo, Wayne R.

    2010-01-01

    The comments from McGrew and Snoke are well received and their concerns for the interpretations in our paper (Premo et al., 2008), which questions the original contention that the Angel Lake orthogneiss is an Archean rock, are many and varied—all of which we will attempt to address. As they point out, this issue is an important one as this particular crustal exposure may delimit the southwestern extent of the Archean Wyoming province (Foster et al., 2006; Mueller and Frost, 2006), which has implications for the true crustal evolution of this region of the Great Basin and perhaps more importantly its relationship (if any) to the location of the world-class gold deposits of north-central Nevada (e.g., Howard, 2003).

  11. Archean crustal evolution of the Narryer Gneiss Terrane, Western Australia, as revealed by the U-Pb age and Hf-isotope compositions of zircon from the granitic gneisses

    Science.gov (United States)

    Sylvester, P.; Souders, K.; Crowley, J. L.; Myers, J.

    2011-12-01

    The Narryer Gneiss Terrane of the Yilgarn Craton, Western Australia, is an important area for studies of early crustal evolution because of the preservation of (1) detrital zircons of Hadean to Archean age in the Jack Hills and Mt. Narryer metasedimentary belts, and (2) several widespread units of granitic gneisses emplaced between ca. 3.7 and 2.6 Ga. We have analyzed the U-Pb geochronology and Hf-isotope geochemistry of magmatic zircons from 38 samples of the granitic gneisses using laser ablation - (multicollector) - ICPMS. The sample suite is dominated by the Meeberrie gneiss, a banded quartz-microcline-oligoclase-biotite gneiss of monzogranite to granodiorite composition, and the Dugel gneiss, a leucocratic, pegmatite-layered syenogranite gneiss, but gneisses of dioritic to tonalitic composition, as well as less deformed granite sheets, are also represented. Magmatic zircons were identified on the basis of the preservation of oscillatory zoning in BSE and CL images, igneous Th/U ratios (>0.2), and concordant U-Pb isotopic systematics with low common Pb contents. The results indicate many of the gneisses are composed of the products of multiple magmatic events, as has been reported previously for samples of the Meeberrie gneiss (Kinny & Nutman, 1996, Precambrian Res. 78, 165-178). Major ages of magmatism preserved in the gneisses occurred at ca. 3685-3665 Ma, 3620-3565 Ma, 3495-3440 Ma, 3375-3330 Ma, and 3300-3260 Ma. The late granite sheets crystallized at 2710-2645 Ma. Hf-isotope compositions of the zircons trend to less radiogenic values with decreasing age, with ɛHf values of ca. 0 to -5 for 3.7-3.4 Ga gneisses, ca. -1 to -9 for 3.4-3.2 Ga gneisses and ca. -5 to -20 for the late granite sheets. The array of the Hf isotopic compositions with time for the entire sample set are fit well by a regression indicating a source reservoir with a 176Lu/177Hf of 0.022 extracted from the depleted mantle at 3.9 Ga. This suggests that the Narryer gneisses and late granite

  12. Fine-scale heat flow, shallow heat sources, and decoupled circulation systems at two sea-floor hydrothermal sites, Middle Valley, northern Juan de Fuca Ridge

    Science.gov (United States)

    Stein, J. S.; Fisher, A. T.; Langseth, M.; Jin, W.; Iturrino, G.; Davis, E.

    1998-12-01

    Fine-scale heat-flow patterns at two areas of active venting in Middle Valley, a sedimented rift on the northern Juan de Fuca Ridge, provide thermal evidence of shallow hydrothermal reservoirs beneath the vent fields. The extreme variability of heat flow is explained by conductive heating immediately adjacent to vents and shallow circulation within sediments above the reservoir. This secondary circulation is hydrologically separated from the deeper system feeding the vents by a shallow conductive lid within the sediments. A similar separation of shallow and deep circulation may also occur at sediment-free ridge-crest hydrothermal environments.

  13. Subsurface deposition of Cu-rich massive sulphide underneath a Palaeoproterozoic seafloor hydrothermal system—the Red Bore prospect, Western Australia

    Science.gov (United States)

    Agangi, Andrea; Reddy, S. M.; Plavsa, D.; Vieru, C.; Selvaraja, V.; LaFlamme, C.; Jeon, H.; Martin, L.; Nozaki, T.; Takaya, Y.; Suzuki, K.

    2018-02-01

    The Proterozoic Bryah and Yerrida basins of Western Australia contain important base and precious metal deposits. Here we present microtextural data, trace element and S isotope analyses of massive sulphide mineralisation hosted in Palaeoproterozoic subvolcanic rocks (dolerite) recently discovered at Red Bore. The small-scale high-grade mineralisation, which extends from the sub-surface to at least 95 m down-hole, is dominated by massive chalcopyrite and contains minor pyrite and Bi-Te-(Se) phases. Massive sulphide mineralisation is surrounded by discontinuous brecciated massive magnetite, and a narrow (data are permissive of a genetic association of Red Bore mineralisation with VHMS deposits nearby, thus suggesting a direct connection between magmatism and mineralising fluids responsible for VHMS deposition at surface. Therefore, the Red Bore mineralisation may represent the magmatic roots of a VHMS system.

  14. Field and geochemical characterisitics of the Mesoarchean (~3075 ma) Ivisaartoq greenstone belt, southern West Greenland: Evidence for seafloor hydrothermal alteration in a supra-subduction oceanic crust

    DEFF Research Database (Denmark)

    Polat, A.; Appel, P.W.U.; Frei, Robert

    2006-01-01

    -enriched, near-flat HREE, and HFSE (especially Nb)-depleted trace element patterns, indicating a subduction zone geochemical signature. Ultramafic pillows and cumulates display large positive initial eNd values of + 1.3 to + 5.0, consistent with a strongly depleted mantle source. Given the geological...... similarities between the Ivisaartoq greenstone belt and Phanerozoic forearc ophiolites, we suggest that the Ivisaartoq greenstone belt represents Mesoarchean supra-subduction zone oceanic crust....... assemblage is interpreted as relict epidosite. The stage II metasomatic assemblage occurs as concordant discontinuous layered calc-silicate bodies to discordant calc-silicate veins commonly associated with shear zones. The stage II metasomatic assemblage consists mainly of diopside...

  15. The magmatic model for the origin of Archean Au-quartz vein ore systems: an assessment of the evidence

    International Nuclear Information System (INIS)

    Spooner, E.T.C.

    1991-01-01

    The magmatic model for the origin of Archean Au-quartz vein ore systems suggests that Au was derived by partition between silicate (± sulphide) melts of certain compositions and H 2 O-CO 2 -NaCl magmatic fluids. Supporting evidence includes partial/structural geological relationships, timing relationships, H and C isotope geochemistry, probable primary Au enrichment in the Lamaque stocks, and fluid inclusion volatile geochemistry. Evidence is currently negative with respect to various within- and sub-greenstone belt metamorphic/deep crustal fluid models for primary Au mineralization; however a U-Pb age for vein stage 3 sphene from the Camflo deposit, Quebec which is ∼ 55-60 Ma younger than the host stock at 2685-2680 Ma indicates dissolution/reprecipitation of Au by late, (?) upper crustal saline fluids. Evidence is accumulating that epithermal-meso thermal Au-Ag mineralization in island arc and cordilleran settings may also have been magmatically derived ± high level fluid mixing from calc-alkaline, shoshonitic and other igneous compositions. (author)

  16. Abiotic Earth - Establishing a Baseline for Earliest Life, Data from the Archean of Western Australia

    Science.gov (United States)

    Lindsay, J. F.; Brasier, M. D.; McLoughlin, N.; Green, O. R.; Fogel, M.; McNamara, K. M.; Steele, A.; Mertzman, S. A.

    2003-01-01

    Stromatolitic structures preserved at two stratigraphic levels within the 3.47-3.43 Ga Warrawoona Group of Western Australia have been interpreted as some of "the least controversial evidence of early life on earth" and "the oldest firmly established biogenic deposits now known from the geologic record". The structures were said to have formed in a shallow sub-tidal to intertidal setting as part of an evaporite succession. In an extensive field program we have re-evaluated exposures of the Strelley Pool Chert from which stromatolites have been described and carried out detailed mapping and sampling of the Strelley Pool West site 13.7 km west of the type locality. Data from our ongoing program cast considerable doubt on the biogenic origins of the stromatolitic structures and on the nature of their depositional setting.

  17. On the nature and origin of garnet in highly-refractory Archean lithosphere: implications for continent stabilisation

    Science.gov (United States)

    Gibson, Sally

    2014-05-01

    The nature and timescales of garnet formation in the Earth's subcontinental lithospheric mantle (SCLM) are important to our understanding of how this rigid outer shell has evolved and stabilised since the Archean. Nevertheless, the widespread occurrence of pyrope garnet in the sub-cratonic mantle remains one of the 'holy grails' of mantle petrology. The paradox is that garnet often occurs in mantle lithologies (dunites and harzburgites) which represent residues of major melting events (up to 40 %) whereas experimental studies on fertile peridotite suggest this phase should be exhausted by years. The garnets display systematic trends from ultra-depleted to enriched compositions that have not been recognised in peridotite suites from elsewhere (Gibson et al., 2013). Certain harzburgite members of the xenolith suite contain the first reported occurrence of pyrope garnets with rare-earth element (REE) patterns similar to hypothetical garnets proposed by Stachel et al. (2004) to have formed in the Earth's SCLM during the Archean, prior to metasomatism. These rare ultra-depleted low-Cr garnets occur in low temperature (~1050 oC) xenoliths derived from depths of ~120 km and coexist in chemical and textural equilibrium with highly-refractory olivine (Fo95.4) and orthopyroxene (Mg#=96.4). These phases are all more magnesian than generally encountered in global samples of depleted mantle, i.e. harzburgites and diamond inclusion suites. The Tanzanian ultra-depleted garnets form interconnecting networks ('necklaces') around grains of orthopyroxene, which is of key importance to their origin. This close spatial relationship of garnet and orthopyroxene together with the major, trace and REE contents of the ultra-depleted garnets, are consistent with an origin by isochemical exsolution. The significance of ultra-depleted low-Cr garnets has not previously been recognised in global suites of mantle xenoliths or diamond inclusions: they appear to have been overlooked, primarily

  18. Pb, Sr, and Nd isotopic compositions of a suite of Large Archean, igneous rocks, eastern Beartooth Mountains - Implications for crust-mantle evolution

    Science.gov (United States)

    Wooden, J. L.; Mueller, P. A.

    1988-01-01

    Compositionally diverse Late Archean rocks (2.74-2.79 Ga old) from the eastern Beartooth Mountains (Montana and Wyoming) were studied and shown to have the same initial Pb, Sr, and Nd isotopic ratios. Lead and Sr initial ratios are higher and Nd initial values lower than predicted for rocks derived from model mantle sources and strongly indicate the involvement of an older crustal reservoir in the genesis of these rocks. A model involving subduction of continental detritus and contamination of the overlying mantle is suggested.

  19. Variability in Rock Thermal Properties in the Late Archean Crust of the Kapuskasing Structural Zone and Implications for its Thermal Structure and Metamorphic History.

    Science.gov (United States)

    Merriman, J. D.; Whittington, A. G.; Hofmeister, A. M.

    2017-12-01

    The thermal properties of rocks such as internal heat production and thermal diffusivity (α) play a key role in determining the thermal structure of the lithosphere, and consequently, the rates and styles of metamorphism within the crust. Over the last decade, measurements of α using the method laser flash analysis have shown the ability of a rock to conduct heat can vary by as much as a factor of 5 between common rock types, and decrease by up to a factor of 10 for the same rock between 25-1000°C. Here we present a preliminary model for the variability in rock throughout the crust based on measurements of the α of a suite of 100 samples from late Archean crust exposed in and around the Kapuskasing Structural Zone in Ontario, Canada. Preliminary results suggest that α is controlled primarily by mineralogy, and can vary not only between different rock types as described above, but also within the same rock by a factor of 1.5 (or more). Thermal diffusivity results were combined with heat producing element concentrations measured with ICP-MS to create a thermal model of the Kapuskasing Structural Zone prior its uplift and exposure. To provide additional constraints for P-T conditions within the pre-uplift KSZ crust, a combination of trace-element and pseudosection thermobarometry was used to estimate metamorphic temperatures during an extended period of crustal stability at the end of the Archean. Preliminary results were compared to finite-difference numerical models of the steady-state geothermal gradient using heat production back-calculated to 2.6 Ga. Results suggest a minimum thickness of the continental lithosphere during the late Archean of at least 150 km. To test the response of the crust to the effects of large thermal events such as pluton emplacement, we also performed time-dependent models of the thermal structure of the pre-uplift KSZ crust. These models suggest that heat from thermal events in the upper and middle crust result in a more insulating

  20. Microfacies of mappable Archean biomats, Moodies Group, Barberton Greenstone Belt, South Africa

    Science.gov (United States)

    Gamper, Antonia; Heubeck, Christoph; Ohnemueller, Frank; Walsh, Maud

    2010-05-01

    coarse-grained sand and subordinate palm-sized planar (apparently brittle) biomat fragments mixed with granule and pebble lag at the channel base. Channel dimensions and erosivity may suggest a subaerial setting and imply that biomat growth either predated a temporary base-level drop or grew on land, presumably in a flat coastal setting. The micromorphology, large lateral extent, and depositional architecture of the biomats indicate a well-developed, adaptable, resistant microbial ecosystem along a medium-energy coast and offer a remarkable window in the conditions under which early life on Earth developed.

  1. Archean crustal growth of the Imataca complex, Amazonian craton: Evidence from U-Pb-Sm-Nd and Rb-Sr geochronology

    International Nuclear Information System (INIS)

    Tassinari, C.C.G.; Teixeira, W; Nutman, A.P; Szabo, G.; Mondin, M.; Sato, K; Santos, A.P; Siso, C.S

    2001-01-01

    The Archean Imataca Complex (IC), NW Amazonian Craton, forms a ENE-trending, fault-bounded block adjacent to the Paleoproterozoic Maroni-Itacai as magmatic arc (2.2 2.0 Ga) (Tassinari and Macambira, 1999). The IC rocks are complexely deformed, exhibiting elongated and symmetrical domes and thrusts combined with isoclinal folds. Transcurrent faults are also important, like the Guri Fault System - a zone of multiple faulting, shearing and mylonitization along the southeastern edge of the IC. In a pre-Pangean reconstruction using paleomagnetic data from rocks of the African counterpart, the Guri System is contiguous to the Sassandra (Ivory coast) and Zednes (Mauritaine) faults, in agreement also with the comparable geologic evolution between the NW Amazonian and the West Africa cratons, during the Archean and Late-Paleoproterozoic. The IC mainly composed of medium- to high grade quartz-feldspathic paragneiss, exhibits extensive mortar, augen, flaser and mylonitic textures. Calc-alkaline gneiss and granitoid rocks of igneous protolith are also present in the IC, as well as dolomitic marbles, orthopyroxene and magnetite quartzites, and BIFs that include huge ore deposits of Algoma type. Moreover, migmatite injections and anatexis (devoid of metasedimentary components) are widespread in the western part of Complex, the largest migmatite mass centered in Cerro La Ceiba. This paper reports zircon U-Pb SHRIMP, Sm-Nd and Rb-Sr isotopic data of different IC rocks in order to investigate their age and geological evolution within the tectonic framework of the Amazonian Craton (au)

  2. The Pale Orange Dot: Spectral Effects of a Hazy Early Earth

    Science.gov (United States)

    Arney, G. N.; Meadows, V. S.; Domagal-Goldman, S. D.; Claire, M.; Schwieterman, E.

    2014-12-01

    Increasing evidence suggests Archean Earth had a photochemical hydrocarbon haze similar to Titan's (Zerkle et al. 2012), with important climate implications (Pavlov et al. 2001, Trainer et al. 2006, Haqq-Misra et al. 2008, Domagal-Goldman et al. 2008, Wolf and Toon 2012). Observations also suggest hazy exoplanets are common (Sing et al. 2011, Kreidberg et al 2014), so hazy planet spectra will be relevant to future exoplanet spectral characterization missions. Here, we consider the implications of hydrocarbon aerosols on the spectrum of Archean Earth, examining the effect of a haze layer on the detectability of spectral features from putative biosignatures and the Rayleigh scattering slope. We also examine haze's impact on the spectral energy distribution at the planetary surface, which may be important to the co-evolution of life with its environment. Because the atmospheric pressure and haze particle composition of the Archean Earth are poorly constrained, we test the impact of atmospheric pressure and particle density on haze formation. Our study uses a modified version of the 1-D photochemical code developed originally by Kasting et al. (1979) to generate a fractal haze in the model Archean atmosphere. The 1-D line-by-line fully multiple scattering Spectral Mapping Atmospheric Radiative Transfer Model (SMART) (Meadows and Crisp 1996) is then used to generate synthetic spectra of early Earth with haze. We find (Fig 1) that haze scattering significantly depletes the radiation at short wavelengths, strongly affecting the spectral region of the Rayleigh slope, a broadband change in spectral shape detectable at low spectral resolution. At the surface, the spectral energy distribution is shifted towards longer wavelengths, which may be important to photosynthetic life. Thus, the haze may have significant effects on biology, which in turn produces the methane that leads to haze formation, creating feedback loops between biology and the planet.

  3. Recycled Archean sulfur in the mantle wedge of the Mariana Forearc and microbial sulfate reduction within an extremely alkaline serpentine seamount

    Science.gov (United States)

    Aoyama, Shinnosuke; Nishizawa, Manabu; Miyazaki, Junichi; Shibuya, Takazo; Ueno, Yuichiro; Takai, Ken

    2018-06-01

    The identification of microbial activity under extreme conditions is important to define potential boundaries of the habitable and uninhabitable zones of terrestrial and extraterrestrial living forms. The subseafloor regimes of serpentinite seamounts in the Mariana Forearc are among the most extreme environments for life on earth owing to the widespread presence of highly alkaline fluids with pH values greater than 12. The potential activity of sulfate-reducing microorganisms has been suggested within the South Chamorro serpentinite seamounts on the basis of depletion of sulfate and enrichment of dissolved sulfide in pore water. However, the vertical distribution of sulfate-reducing microorganisms and the origin of sulfate are still uncertain. To address these issues, we analyzed quadruple sulfur isotopes of sulfide minerals and pore water sulfate in the upper 56 m of sedimentary sequences at the summit of the S. Chamorro Seamount and those of dissolved sulfate in upwelling fluids collected as deep as 202 mbsf (meters below the seafloor) in a cased hole near the summit of the same seamount. The depth profiles of the concentrations and the δ34S and Δ33S‧ values of sulfide minerals and pore water sulfate indicate microbial sulfate reduction as deep as 30 mbsf. Further, apparent isotopic fractionations (34ε) and exponents of mass dependent relationships (33λ) during sulfate reduction are estimated to be 62 ± 14‰ and 0.512 ± 0.002, respectively. The upwelling fluids show both the chlorine depletion relative to seawater and the negative δ15N values of ammonia (-4‰). Although these signatures point to dehydration of the subducting oceanic plate, the negative Δ33S‧ values of sulfate (-0.16‰ to -0.26‰ with analytical errors of ±0.01‰) are unlikely to originate from surrounding modern crusts. Instead, sulfate in the upwelling fluid likely possess non-mass-dependent (NMD) sulfur. Because NMD sulfur was produced primarily in the Archean atmosphere, our

  4. New age (ca. 2970 Ma), mantle source composition and geodynamic constraints on the Archean Fiskenæsset anorthosite complex, SW Greenland

    DEFF Research Database (Denmark)

    Polat, A; Frei, Robert; Scherstén, Anders

    2010-01-01

    The Archean Fiskenæsset Complex, SW Greenland, consists of an association of ca. 550-meter-thick layered anorthosite, leucogabbro, gabbro, and ultramafic rocks (peridotite, pyroxenite, dunite, hornblendite). The complex was intruded by tonalite, trondhjemite, and granodiorite (TTG) sheets (now...... orthogneisses) during thrusting that was followed by several phases of isoclinal folding. The trace element systematics of the Fiskenæsset Complex and associated volcanic rocks are consistent with a supra-subduction zone geodynamic setting. The Fiskenæsset anorthosites, leucogabbros, gabbros and ultramafic...... rocks collectively yield an Sm–Nd errorchron age of 2973 ± 28 Ma (MSWD = 33), with an average initial eNd = + 3.3 ± 0.7, consistent with a long-term depleted mantle source. Regression of Pb isotope data define an age of 2945 ± 36 Ma (MSWD = 44); and the regression line intersects the average growth...

  5. Finding the Needles in the Haystacks: High-Fidelity Models of the Modern and Archean Solar System for Simulating Exoplanet Observations

    Science.gov (United States)

    Roberge, Aki; Rizzo, Maxime J.; Lincowski, Andrew P.; Arney, Giada N.; Stark, Christopher C.; Robinson, Tyler D.; Snyder, Gregory F.; Pueyo, Laurent; Zimmerman, Neil T.; Jansen, Tiffany; hide

    2017-01-01

    We present two state-of-the-art models of the solar system, one corresponding to the present day and one to the Archean Eon 3.5 billion years ago. Each model contains spatial and spectral information for the star, the planets, and the interplanetary dust, extending to 50 au from the Sun and covering the wavelength range 0.3-2.5 micron. In addition, we created a spectral image cube representative of the astronomical backgrounds that will be seen behind deep observations of extrasolar planetary systems, including galaxies and Milky Way stars. These models are intended as inputs to high-fidelity simulations of direct observations of exoplanetary systems using telescopes equipped with high-contrast capability. They will help improve the realism of observation and instrument parameters that are required inputs to statistical observatory yield calculations, as well as guide development of post-processing algorithms for telescopes capable of directly imaging Earth-like planets.

  6. New Sm/Nd and U/Pb geochronological constraints of the Archean to neoproterozoic evolution of the Amparo basement complex of the Central Ribeira Belt, Southeastern Brazil

    International Nuclear Information System (INIS)

    Fetter, A.H.; Hackspacher, P.C.; Ebbert, H.D; Dantas, E.L; Costa, A.C.D. da

    2001-01-01

    The Amparo Basement Complex is a distinctive collage of migmatitic tronjhemitetonalite- granodiorite (TTG) orthogneisses that represents the older basement exposures within the Central Ribeira Belt, a Late Neoproterozoic (ca. 600 Ma) collisional belt in southeastern Brazil. These basement gneisses are overlain by Mesoproterozoic to Neoproterozoic supracrustal sequences, and intruded by Neoproterozoic collisional granitoids. Pioneering Rb/Sr, Pb/Pb and K/Ar geochronological studies of the Amparo Complex, e.g. (Wernick et al., 1981; Wernick and Oliveira, 1986; Arthur, 1988; Tassinari, 1988; Campos Neto, 1991) provided some initial insights into the antiquity and geologic evolution of the complex, but little about the crustal evolution of the constituent gneisses. Furthermore, the susceptibility of these systems to partial isotopic resetting, left some doubt about the timing and true number of geologic events recorded by these polydeformed rocks. Recent Sm/Nd whole rock (Dantas et al., 2000) and new U/Pb single crystal zircon and monazite data obtained from the Amparo Complex, however, now furnish information on the crustal growth history of the basement and provide precise age constraints on the timing of events related to the geologic evolution of the complex. Based on these new data, it appears that the oldest rocks within the complex are polymigmatized tronjhemitic gneisses located near the town of Amparo. The oldest phase of this migmatite yields a U/Pb zircon age of 3,024 +/- 9 Ma. Sm/Nd data from this locale yields a Nd T(DM) model age of 3.28 Ga suggesting that the genesis of this crustal unit involved some input from yet older crust. Data from banded tonalitic gneisses collected ca. 50 km south of Amparo indicate that subsequent Archean crustal growth around the older core occurred around 2.77 Ga (U/Pb zircon age of 2,772 +/- 26 Ma. A Nd T(DM) model age of 3.02 Ga obtained from these tonalites also indicate enrichment from older crustal sources during their

  7. Archean and proterozoic in the West-European Hercynian chain: isotopic geochemistry (Sr-Nd-Pb) and U-Pb geochronology on zircons

    International Nuclear Information System (INIS)

    Guerrot, C.

    1989-01-01

    The first part of this research thesis reports the study of isotopic (Sr-Nd-Pb) geochemistry and U-Pb geochronology on zircons in the immersed granulites of the Bay of Biscay: U-Pb geochronology on zircons, Nd isotopic geochemistry, Sr isotopic geochemistry, common Pb, Rb-Sr, Sm-Nd and rare earth data on minerals, comparison with other European granulites, comparison with West-Africa, study of Archean and proterozoic in the Hercynian chain. The second part reports the study of the U-Pb geochronology on zircon in the Cadomian, and the third part addresses the Sr-Nd isotopic geochemistry of some Cadomian granitoid, and the crust contamination in different regions [fr

  8. The Archean komatiite-hosted, PGE-bearing Ni-Cu sulfide deposit at Vaara, eastern Finland: evidence for assimilation of external sulfur and post-depositional desulfurization

    Science.gov (United States)

    Konnunaho, J. P.; Hanski, E. J.; Bekker, A.; Halkoaho, T. A. A.; Hiebert, R. S.; Wing, B. A.

    2013-12-01

    Archean komatiites host important resources of Ni, Cu, Co, and PGE, particularly in Western Australia and Canada. In Finland, several small, low-grade sulfide deposits have been found in komatiites, including the ca. 2.8 Ga Vaara deposit in the Archean Suomussalmi greenstone belt. It occurs in the central part of the serpentinized olivine cumulate zone of a komatiitic extrusive body and is composed of disseminated interstitial sulfides consisting of pyrite, pentlandite, millerite, violarite, and chalcopyrite accompanied by abundant magnetite. Although currently subeconomic, the mineralization is interesting due to the very high chalcophile element contents of the sulfide fraction (38 wt% Ni, 3.4 wt% Cu, 0.7 wt% Co, 22.4 ppm Pd, and 9.5 ppm Pt). The sulfides occur in relatively Cr-poor olivine cumulates suggesting involvement of a chromite-undersaturated magma. The parental magma was an Al-undepleted komatiite with an estimated MgO content of at least 24 wt%. In contrast to the common komatiite types in the eastern Finland greenstone belts, the Vaara rocks are moderately enriched in LREE relative to MREE, suggesting that crustal contamination played an important role in the genesis of the Vaara deposit. Multiple sulfur isotope data reveal considerable mass-independent sulfur isotope fractionation both in country rock sedimentary sulfides (Δ33S ranges from -0.50 to +2.37 ‰) and in the Vaara mineralization (Δ33S ranges from +0.53 to +0.66 ‰), which provides strong evidence for incorporation of crustal sulfur. Extensive replacement of interstitial sulfides by magnetite and the presence of millerite- and violarite-bearing, pyrrhotite-free sulfide assemblages indicate significant post-magmatic, low-temperature hydrothermal oxidation of the primary magmatic pyrrhotite-pentlandite-chalcopyrite assemblages and associated sulfur loss that led to a significant upgrading of the original metal tenors of the Vaara deposit.

  9. Iron oxides, divalent cations, silica, and the early earth phosphorus crisis

    DEFF Research Database (Denmark)

    Jones, C.; Nomosatryo, S.; Crowe, S.A.

    2015-01-01

    As a nutrient required for growth, phosphorus regulates the activity of life in the oceans. Iron oxides sorb phosphorus from seawater, and through the Archean and early Proterozoic Eons, massive quantities of iron oxides precipitated from the oceans, producing a record of seawater chemistry...... that is preserved as banded iron formations (BIFs) today. Here we show that Ca2+, Mg2+, and silica in seawater control phosphorus sorption onto iron oxides, influencing the record of seawater phosphorus preserved in BIFs. Using a model for seawater cation chemistry through time, combined with the phosphorus...... waters shifted from phosphorus to iron limiting....

  10. Direct thermal effects of the Hadean bombardment did not limit early subsurface habitability

    Science.gov (United States)

    Grimm, R. E.; Marchi, S.

    2018-03-01

    Intense bombardment is considered characteristic of the Hadean and early Archean eons, yet some detrital zircons indicate that near-surface water was present and thus at least intervals of clement conditions may have existed. We investigate the habitability of the top few kilometers of the subsurface by updating a prior approach to thermal evolution of the crust due to impact heating, using a revised bombardment history, a more accurate thermal model, and treatment of melt sheets from large projectiles (>100 km diameter). We find that subsurface habitable volume grows nearly continuously throughout the Hadean and early Archean (4.5-3.5 Ga) because impact heat is dissipated rapidly compared to the total duration and waning strength of the bombardment. Global sterilization was only achieved using an order of magnitude more projectiles in 1/10 the time. Melt sheets from large projectiles can completely resurface the Earth several times prior to ∼4.2 Ga but at most once since then. Even in the Hadean, melt sheets have little effect on habitability because cooling times are short compared to resurfacing intervals, allowing subsurface biospheres to be locally re-established by groundwater infiltration between major impacts. Therefore the subsurface is always habitable somewhere, and production of global steam or silicate-vapor atmospheres are the only remaining avenues to early surface sterilization by bombardment.

  11. U/Pb (SHRIMP), 207Pb/206Pb, Rb/Sr, Sm/Nd e K/Ar geochronology of granite-greenstone terrains of Gaviao Block: implications for the Proterozoic and Archean evolution of Sao Francisco Craton, Brazil

    International Nuclear Information System (INIS)

    Leal, Luiz Rogerio Bastos

    1998-01-01

    The Gaviao Block (GB) in the northern portion of the Sao Francisco Craton-Northeast of Brazil, constitutes one of the oldest Archean fragments of the South American Platform Archean crust. GB underwent several events of juvenile accretion and reworking of continental crust along its evolutionary history, notably between the Archean and the Paleoproterozoic. 207 Pb/ 206 Pb isotopic analyses were carried out in two zircons populations from strongly migmatized TTG terranes found in the proximity of Brumado: the first population (7 crystals) is taken as representative of the crystallization period of the TTG terranes at 3300 ± 45 Ma; the second (2 crystals) represents the age of the first even of metamorphism/migmatization at 2910 ± 10 Ma. 207 Pb/ 206 Pb analyses in zircons from an outcrop of non-migmatized TTG in the area yielded a 3202 ± 15 Ma age (4 crystals), interpreted to be the crystallization period of the gneiss protolith. Sm/Nd analyses on the TTG rocks of the Brumado region yielded T DM model ages varying between 3.26 and 3.36 Ga and ε Nd (t) between -3.5 and +0.7. These data suggest the occurrence of juvenile accretions to the continental crust during the Archean, with differential involvement of crustal materials. The geochemical data of rare earth elements corresponding to the TTG terranes revealed moderate LRRE contents (La N =83,5), low HREE contents (La N =2,5) and a fairly fractionated pattern (La/Yb) N =34, besides lack of negative Eu anomaly, showing that these rocks have similar compositions to those TTG terranes of cratonic continents, as well as some Archean rocks from CSF (e.g. Sete Voltas, Boa Vista). Finally, the youngest ages present in GB rocks (ca. 1.2-0.45 Ga) represent the role played by tectono thermal events, which produced partial or total rejuvenation of the Rb/Sr and K/Ar isotopic systems during the Espinhaco and Brasiliano cycles. In particular, K/Ar ages illustrate the effect of younger regional cooling episodes related to the

  12. The complex systematics of zircons in migmatitic gneisses: An example from an Archean migmatite along the Patos Shear Zone, Borborema Province, NE Brazil

    International Nuclear Information System (INIS)

    Costa, A.C.D; Hackspacher, P.C; Dantas, E.L; Fetter, A.H.

    2001-01-01

    The Northem Tectonic Domain Borborema Province, in Northeast of Brazil records a complex history of tectonic activity ranging from 3.4 Ga to 0.6 Ga (Brito Neves, 1995 and Dantas, 1996). U-Pb systematics of zircons from a migmatitic gneiss just north of the Patos Shear Zone provide an excellent example of the difficulties encountered using conventional single-grain U/Pb zircon geochronology in polydeformed gneiss terranes. Our conventional single grain zircon analyses of a migmatite yielded Archean ages between ca. 3.3 at 2.8 a, as well as some highly discordant Paleoproterozoic ages. Subsequent cathodoluminescence images of these zircon grains showed complex internal structures that possibly record up to 4 separate stages of zircon growth. With such internal complexity, is impossible resolve primary crystallization ages as well as the ages of subsequent overgrowth events using conventional single grain analyses. Such resolution will require analyses of the individual grain domains using the SHRIMP method (au)

  13. Evidence for Microbial Activity in ~3.5 Ga Pillow Basalts From the Barberton Greenstone Belt, South Africa

    Science.gov (United States)

    Muehlenbachs, K.; Banerjee, N. R.; Furnes, H.; Staudigel, H.; de Wit, M.

    2004-05-01

    We have discovered biosignatures in the formerly glassy rims of pillow lavas from the Mesoarchean Barberton Greenstone Belt (BGB) in South Africa. Over the last decade, bioalteration of basaltic glass in pillow lavas and volcaniclastic rocks has been well documented from in-situ oceanic crust and well-preserved Phanerozoic ophiolites. Much of the debate regarding the biogenicity of purported microfossils of early life centers on the interpretation of the host rocks' protoliths. To date, most protoliths have been interpreted to be of sedimentary origin. Some workers have proposed alternate origins for these substrates, including hydrothermal and even volcanic derivation, to cast doubt on their putative biogenicity. Hence studies documenting evidence for early life have proven to be controversial. Here we document evidence for microbial activity in ~3.5 Ga subaqueous volcanic rocks that represent a new, unambiguous geological setting in the search for early life on Earth. The BGB magmatic sequence is dominated by mafic to ultramafic pillow lavas, sheet flows, and intrusions interpreted to represent 3480- to 3220-million-year-old oceanic crust and island arc assemblages. The BGB pillow lavas are exceptionally well-preserved and represent unequivocal evidence that these rocks were erupted in a subaqueous environment. The formerly glassy rims of the BGB pillow lavas contain micron-sized, microbially generated, tubular structures consisting of titanite. These structures are interpreted to have formed during microbial etching of the originally glassy pillow rims and were subsequently mineralized by titanite during greenschist facies seafloor hydrothermal alteration. Overlapping metamorphic and magmatic dates from the pillow lavas suggest this process occurred soon after eruption of the pillow lavas on the seafloor. X-ray mapping has revealed the presence of carbon along the margins of the tubular structures. Disseminated carbonates within the microbially altered BGB

  14. A petrological view of early Earth geodynamics

    Science.gov (United States)

    Herzberg, C.

    2003-04-01

    primary magmas contained 14 to 22% MgO, similar to Reykjanes MORB, Gorgona, Hawaii, and the early Icelandic plume in the model of Herzberg & O'Hara (2002). However, a few xenoliths record T_P as low as 1300oC. Two geodynamic interpretations follow: 1) Archean cratonic mantle formed as residues below ridges and hotspots similar to those of today, except the lithosphere was somewhat thinner in some cases, 2) Archean cratonic mantle formed as residues below hot ridges in most cases. Early Proterozoic sheeted dikes and eruptives from the Cape Smith Belt in Canada are consistent with the hot ridge interpretation. Ridge potential temperatures could have been 1520-1570oC, higher than modern ridges (1300-1450oC) but similar to those for the Gorgona and early Tertiary Icelandic plumes.

  15. Development of a mixed seawater-hydrothermal fluid geochemical signature during alteration of volcanic rocks in the Archean (∼2.7 Ga) Abitibi Greenstone Belt, Canada

    Science.gov (United States)

    Brengman, Latisha A.; Fedo, Christopher M.

    2018-04-01

    conclude that seafloor silicification in hydrothermal depositional settings is capable of producing rocks that resemble marine chemical precipitates such as banded iron formation, and could be a process that is widespread in the Archean. Consequently, because silicified volcanic rocks from the HMG possess mixed seawater and hydrothermal rare-earth element characteristics similar to Archean iron formations and cherts, we suggest caution must be exercised when interpreting the geochemical information preserved in metamorphosed rocks where original genesis is unknown.

  16. Re-Os ages for Archean molybdenite and pyrite, Kuittila-Kivisuo, Finland and Proterozoic molybdenite, Kabeliai, Lithuania: Testing the chronometer in a metamorphic and metasomatic setting

    Science.gov (United States)

    Stein, H.J.; Sundblad, K.; Markey, R.J.; Morgan, J.W.; Motuza, G.

    1998-01-01

    that the Re-Os isotopic system in pyrite has been reset on the millimeter scale and that the 21 ppt 187Os intercept reflects the in situ decay of 187Re during the ~160 to 170 m.y. interval from ~2778 Ma (time of molybdenite ± pyrite deposition) to ~2607 Ma (time of pyrite resetting). When the Re-Os data for molybdenites from the nearby Kivisuo prospect are plotted together with the Kuittila molybdenite and pyrite data, a well-constrained five-point isochron with an age of 2780 ± 8 Ma and a 187Os intercept (-2.4 ± 3.8 ppt) of essentially zero results (MSWD = 1.5). We suggest that the pyrite isochron age records a regional metamorphic and/or hydrothermal event, possibly the time of Au mineralization. A proposed Re-Os age of ~2607 Ma for Au mineralization is in good agreement with radiometric ages by other methods that address the timing of Archean Au mineralization in deposits worldwide (so-called 'late Au model'). Molybdenite, in contrast, provides a robust Re-Os chronometer, retaining its original formation age of ~2780 Ma, despite subsequent metamorphic disturbances in Archean and Proterozoic time.

  17. Oxidative release of chromium from Archean ultramafic rocks, its transport and environmental impact – A Cr isotope perspective on the Sukinda valley ore district (Orissa, India)

    International Nuclear Information System (INIS)

    Paulukat, Cora; Døssing, Lasse N.; Mondal, Sisir K.; Voegelin, Andrea R.; Frei, Robert

    2015-01-01

    Highlights: • Cr in lateritic soil profiles in Sukinda valley are partly highly negatively fractionated. • Oxidative weathering and mining operations affect the Cr isotope composition of the local surface water. • Isotopically heavy Cr from land is probably preserved during its transport to the sea. • The environmental impact of toxic Cr(VI) can potentially be diminished by microbial mats. - Abstract: This study investigates Cr isotope fractionation during soil formation from Archean (3.1–3.3 Ga) ultramafic rocks in a chromite mining area in the southern Singhbhum Craton (Orissa, India). The Cr-isotope signatures of two studied weathering profiles, range from non-fractionated mantle values to negatively fractionated values as low as δ 53 Cr = −1.29 ± 0.04‰. Local surface waters are isotopically heavy relative to the soils. This supports the hypothesis that during oxidative weathering isotopically heavy Cr(VI) is leached from the soils to runoff. The impact of mining pollution is observed downstream from the mine where surface water Cr concentrations are significantly increased, accompanied by a shift to less positive δ 53 Cr values relative to upstream unpolluted surface water. A microbial mat sample indicates that microbes have the potential to reduce and immobilize Cr(VI), which could be a factor in controlling the hazardous impact of Cr(VI) on health and environment. The positive Cr isotope signatures of the Brahmani estuary and coastal seawater collected from the Bay of Bengal further indicate that the positively fractionated Cr isotope signal from the catchment area is preserved during its transport to the sea. Isotopically lighter Cr(VI) downstream from the mine is probably back-reduced to Cr(III) during riverine transport leading to similar Cr-isotope values in the estuary as observed upstream from the mine

  18. Constraining the climate and ocean pH of the early Earth with a geological carbon cycle model.

    Science.gov (United States)

    Krissansen-Totton, Joshua; Arney, Giada N; Catling, David C

    2018-04-17

    The early Earth's environment is controversial. Climatic estimates range from hot to glacial, and inferred marine pH spans strongly alkaline to acidic. Better understanding of early climate and ocean chemistry would improve our knowledge of the origin of life and its coevolution with the environment. Here, we use a geological carbon cycle model with ocean chemistry to calculate self-consistent histories of climate and ocean pH. Our carbon cycle model includes an empirically justified temperature and pH dependence of seafloor weathering, allowing the relative importance of continental and seafloor weathering to be evaluated. We find that the Archean climate was likely temperate (0-50 °C) due to the combined negative feedbacks of continental and seafloor weathering. Ocean pH evolves monotonically from [Formula: see text] (2σ) at 4.0 Ga to [Formula: see text] (2σ) at the Archean-Proterozoic boundary, and to [Formula: see text] (2σ) at the Proterozoic-Phanerozoic boundary. This evolution is driven by the secular decline of pCO 2 , which in turn is a consequence of increasing solar luminosity, but is moderated by carbonate alkalinity delivered from continental and seafloor weathering. Archean seafloor weathering may have been a comparable carbon sink to continental weathering, but is less dominant than previously assumed, and would not have induced global glaciation. We show how these conclusions are robust to a wide range of scenarios for continental growth, internal heat flow evolution and outgassing history, greenhouse gas abundances, and changes in the biotic enhancement of weathering. Copyright © 2018 the Author(s). Published by PNAS.

  19. Photosynthetic microbial mats today, on early Earth, (and on early Mars?)

    Science.gov (United States)

    Des Marais, D. J.

    2008-05-01

    extensive, highly productive biosphere? Perhaps the substantial decline in geothermal activity during the Archean created a driver for the development of oxygenic photosynthesis. Can we further document the Archean biosphere? The pre-3.5 Ga crust of Mars records evidence of surface water and is far better preserved than the early crust of Earth. Perhaps Mars exploration will extend our understanding of emerging biospheres to even earlier periods.

  20. Identifying early Earth microfossils in unsilicified sediments

    Science.gov (United States)

    Javaux, Emmanuelle J.; Asael, Dan; Bekker, Andrey; Debaille, Vinciane; Derenne, Sylvie; Hofmann, Axel; Mattielli, Nadine; Poulton, Simon

    2013-04-01

    The search for life on the early Earth or beyond Earth requires the definition of biosignatures, or "indices of life". These traditionally include fossil molecules, isotopic fractionations, biosedimentary structures and morphological fossils interpreted as remnants of life preserved in rocks. This research focuses on traces of life preserved in unsilicified siliciclastic sediments. Indeed, these deposits preserve well sedimentary structures indicative of past aqueous environments and organic matter, including the original organic walls of microscopic organisms. They also do not form in hydrothermal conditions which may be source of abiotic organics. At our knowledge, the only reported occurrence of microfossils preserved in unsilicified Archean sediments is a population of large organic-walled vesicles discovered in shales and siltstones of the 3.2 Ga Moodies Group, South Africa. (Javaux et al, Nature 2010). These have been interpreted as microfossils based on petrographic and geochemical evidence for their endogenicity and syngeneity, their carbonaceous composition, cellular morphology and ultrastructure, occurrence in populations, taphonomic features of soft wall deformation, and the geological context plausible for life, as well as lack of abiotic explanation falsifying a biological origin. Demonstrating that carbonaceous objects from Archaean rocks are truly old and truly biological is the subject of considerable debate. Abiotic processes are known to produce organics and isotopic signatures similar to life. Spheroidal pseudofossils may form as self-assembling vesicles from abiotic CM, e.g. in prebiotic chemistry experiments (Shoztak et al, 2001), from meteoritic lipids (Deamer et al, 2006), or hydrothermal fluids (Akashi et al, 1996); by artifact of maceration; by migration of abiotic or biotic CM along microfractures (VanZuilen et al, 2007) or along mineral casts (Brasier et al, 2005), or around silica spheres formed in silica-saturated water (Jones and

  1. A new method of discriminating different types of post-Archean ophiolitic basalts and their tectonic significance using Th-Nb and Ce-Dy-Yb systematics

    Directory of Open Access Journals (Sweden)

    Emilio Saccani

    2015-07-01

    Full Text Available In this paper, a new discrimination diagram using absolute measures of Th and Nb is applied to post-Archean ophiolites to best discriminate a large number of different ophiolitic basalts. This diagram was obtained using >2000 known ophiolitic basalts and was tested using ∼560 modern rocks from known tectonic settings. Ten different basaltic varieties from worldwide ophiolitic complexes have been examined. They include two basaltic types that have never been considered before, which are: (1 medium-Ti basalts (MTB generated at nascent forearc settings; (2 a type of mid-ocean ridge basalts showing garnet signature (G-MORB that characterizes Alpine-type (i.e., non volcanic rifted margins and ocean-continent transition zones (OCTZ. In the Th-Nb diagram, basalts generated in oceanic subduction-unrelated settings, rifted margins, and OCTZ can be distinguished from subduction-related basalts with a misclassification rate <1%. This diagram highlights the chemical variation of oceanic, rifted margin, and OCTZ basalts from depleted compositions to progressively more enriched compositions reflecting, in turn, the variance of source composition and degree of melting within the MORB-OIB array. It also highlights the chemical contributions of enriched (OIB-type components to mantle sources. Enrichment of Th relative to Nb is particularly effective for highlighting crustal input via subduction or crustal contamination. Basalts formed at continental margin arcs and island arc with a complex polygenetic crust can be distinguished from those generated in intra-oceanic arcs in supra-subduction zones (SSZ with a misclassification rate <1%. Within the SSZ group, two sub-settings can be recognized with a misclassification rate <0.5%. They are: (1 SSZ influenced by chemical contribution from subduction-derived components (forearc and intra-arc sub-settings characterized by island arc tholeiitic (IAT and boninitic basalts; (2 SSZ with no contribution from subduction

  2. The role of impacts in the history of the early earth

    Science.gov (United States)

    French, Bevan M.

    1991-01-01

    The significant conclusions of a conference called 'Meteorite Impact and the Early Earth' are reported including data which support the notion that extraterrestrial impacts greatly influenced the development of the earth. The cratering of other planetary surfaces is discussed, and the energy added by meteorite impacts is characterized. The primary effects of large impacts are set forth in terms of atmospheric, oceanic, and biological considerations which suggest that the ramifications would have been significant. Contentious issues include the variation of impact rate with time in the early universe, the interpretation of the record of intense bombardment in the lunar highlands, and the effects related to alternative scenarios. Directions of future study are mentioned including the identification of terrestrial impact structures, conducting searches in the Archean, and assessing ancient impact rates.

  3. Stable isotope and fluid inclusion signatures of hydrothermal fluids in transcrustal fault zones: significance for orogenic, Archean lode-gold mineralization

    International Nuclear Information System (INIS)

    Neumayr, P.; Hagemann, S.G.; Groves, D.I.

    1999-01-01

    mil). Calculated d 18 O fluid compositions for quartz in the CTZ range from 8.0 to 10.3 per mil at 350 deg C (based on arsenopyrite and chlorite thermometry). Hydrogen isotopes from fluid inclusion waters trapped in quartz have a large variation from -62.5 per mil to -7.2 per mil in the CTZ fluids, whereas hydrogen in fluid inclusions in quartz in the second- and third-order shear zones shows a restricted range from -67.6 to -39.8 per mil. The oxygen isotope shift of about 2 per mil from the CTZ to the second- and third-order fault zones may be explained by two competing processes: 1) the hydrothermal fluids in the CTZ equilibrated, at least partially, with metasedimentary rocks in the footwall, and or 2) there was fractionation of oxygen isotopes during phase immiscibility of a combined H 2 O-CO 2 fluid. The preferential trapping of CO 2 -rich fluids in the CTZ, and H 2 O-rich fluids in the second- and third-order fault zones, therefore, could account for the shift in d 18 O. At present, the first process is preferred, because of the ubiquitous presence of the metasedimentary rocks in the footwall and the consistent d 18 O composition of the CTZ, even in hydrothermal quartz veins which contain significant H 2 O. The large variation in the hydrogen isotopes in fluid inclusions in quartz in the CTZ may be explained by late Archean and post-Archean reactivation of the CTZ and the introduction of fluids related to late-fractures fills, whereas apparently minor reactivation of the second- and third-order structures resulted in a restricted range of dD. Copyright (1999) Geological Society of Australia

  4. Phosphogenesis in the 2460 and 2728 million-year-old banded iron formations as evidence for biological cycling of phosphate in the early biosphere.

    Science.gov (United States)

    Li, Yi-Liang; Sun, Si; Chan, Lung S

    2012-01-01

    The banded iron formation deposited during the first 2 billion years of Earth's history holds the key to understanding the interplay between the geosphere and the early biosphere at large geological timescales. The earliest ore-scale phosphorite depositions formed almost at ∼2.0-2.2 billion years ago bear evidence for the earliest bloom of aerobic life. The cycling of nutrient phosphorus and how it constrained primary productivity in the anaerobic world of Archean-Palaeoproterozoic eons are still open questions. The controversy centers about whether the precipitation of ultrafine ferric oxyhydroxide due to the microbial Fe(II) oxidation in oceans earlier than 1.9 billion years substantially sequestrated phosphate, and whether this process significantly limited the primary productivity of the early biosphere. In this study, we report apatite radial flowers of a few micrometers in the 2728 million-year-old Abitibi banded iron formation and the 2460 million-year-old Kuruman banded iron formation and their similarities to those in the 535 million-year-old Lower Cambrian phosphorite. The lithology of the 535 Million-year-old phosphorite as a biosignature bears abundant biomarkers that reveal the possible similar biogeochemical cycling of phosphorus in the Later Archean and Palaeoproterozoic oceans. These apatite radial flowers represent the primary precipitation of phosphate derived from the phytoplankton blooms in the euphotic zones of Neoarchean and Palaoeproterozoic oceans. The unbiased distributions of the apatite radial flowers within sub-millimeter bands do not support the idea of an Archean Crisis of Phosphate. This is the first report of the microbial mediated mineralization of phosphorus before the Great Oxidation Event when the whole biosphere was still dominated by anaerobic microorganisms.

  5. Evolution of the Archean continental crust in the nucleus of the Yangtze block: Evidence from geochemistry of 3.0 Ga TTG gneisses in the Kongling high-grade metamorphic terrane, South China

    Science.gov (United States)

    Qiu, Xiao-Fei; Ling, Wen-Li; Liu, Xiao-Ming; Lu, Shan-Song; Jiang, Tuo; Wei, Yun-Xu; Peng, Lian-Hong; Tan, Juan-Juan

    2018-04-01

    Archean Tonalite-Trondhjemite-Granodiorite (TTG) rocks are scattered within the Kongling high-grade metamorphic terrane (KHMT) in the northern South China block. A comprehensive geochronological and geochemical study is carried out on the Taoyuan granitic gneisses, a newly recognized TTG suite in the northwestern KHMT. This suite has long been regarded as a Mesoproterozoic magmatic pluton, but U-Pb zircon ages of 2994 ± 22 Ma and 2970 ± 15 Ma are obtained by LA-ICP-MS method in this study. The Taoyuan gneiss suite is trondhjemitic in composition, and has high SiO2 (67.80-74.93 wt.%), Na2O (5.11-5.81 wt.%) contents with Na2O/K2O ratios greater than unity, and low Ni (2.56-7.61 ppm), Cr (1.26-7.67 ppm), Yb (0.32-0.82 ppm) and Y (4.48-11.5 ppm) contents. Plots show large variation in La/Yb and Sr/Y ratios and pronounced depletion in Nb, Ta and Ti in the primitive mantle-normalized spiderdiagram. The gneiss suite also displays two-stage Nd model ages close to its crystallization age with corresponding εNd(t) values of -2.5 to +3.5. It is thus suggested that the Taoyuan gneisses, in fact, is part of the Archean Kongling basement complex. Geochemical evidence implies that the TTG rocks may be derived from partial melting of subducted oceanic crust from a garnetiferous amphibolite source with residual assemblage of garnet + amphibole + plagioclase. Our study further indicates that the nucleus of the Yangtze block might experience a juvenile continental crustal growth during Mesoarchean. We also suggest that the Yangtze block may have its own crustal evolutionary history independent from the North China craton and the Tarim block before Paleoproterozoic.

  6. Origin of the Early Sial Crust and U-Pb Isotope-Geochemical Heterogeneity of the Earth's Mantle

    Science.gov (United States)

    Mishkin, M. A.; Nozhkin, A. D.; Vovna, G. M.; Sakhno, V. G.; Veldemar, A. A.

    2018-02-01

    It is shown that presence of the Early Precambrian sial crust in the Indo-Atlantic segment of the Earth and its absence in the Pacific has been caused by geochemical differences in the mantle underlying these segments. These differences were examined on the basis of Nd-Hf and U-Pb isotopes in modern basalts. The U-Pb isotope system is of particular interest, since uranium is a member of a group of heat-generating radioactive elements providing heat for plumes. It is shown that in the Indo-Atlantic segment, a distribution of areas of the modern HIMU type mantle is typical, while it is almost completely absent in the Pacific segment. In the Archean, in the upper HIMU type paleo-mantle areas, plume generation and formation of the primordial basic crust occurred; this was followed by its remelting resulting in the appearance of an early sial crust forming cratons of the Indo-Atlantic segment.

  7. Abiotic synthesis of porphyrins and other oligopyrroles on the early Earth and Earth-like planets

    Science.gov (United States)

    Fox, S.; Strasdeit, H.

    2013-09-01

    It is generally accepted that abiotically formed amino acids existed on Earth in the late Hadean and early Archean (four billion years ago). They were mainly dissolved in a salty primordial ocean. At that time, volcanic islands were much more abundant than today. It is therefore reasonable to assume that, at hot volcanic coasts, amino acids could have been thermally transformed into other organic molecules. Based on this scenario, we conducted laboratory experiments that simulated the interaction between amino acid-containing sea water and hot lava. In these experiments, a large number of different volatile products were formed, among them pyrroles. It was also possible to obtain porphyrins and other oligopyrroles from pyrroles under simulated conditions of primordial volcanic islands. All experiments were conducted under plausible prebiotic conditions. Our results reveal an abiotic pathway to possible precursors of oligopyrrole-type biomolecules, such as heme and chlorophylls.

  8. Early Neoarchaean A-type granitic magmatism by crustal reworking ...

    Indian Academy of Sciences (India)

    29

    marginal part of the Singhbhum craton whose origin and role in crustal evolution are poorly ...... Lu-Hf and Sm-Nd isotope systematics of Archean komatiites; Earth Planet. ..... Association Commission on New Minerals and Mineral Names; Can.

  9. Early discontinuation

    DEFF Research Database (Denmark)

    Hansen, Dorte Gilså; Felde, Lina; Gichangi, Anthony

    2007-01-01

    prevalence and rate of early discontinuation of different drugs consisting of, in this study, lipid-lowering drugs, antihypertensive drugs, antidepressants, antidiabetics and drugs against osteoporosis. Material and methods This was a register study based on prescription data covering a 4-year period...... and consisting of 470,000 citizens. For each practice and group of drug, a 1-year prevalence for 2002 and the rate of early discontinuation among new users in 2002-2003 were estimated. Early discontinuation was defined as no prescriptions during the second half-year following the first prescription....... There was a positive association between the prevalence of prescribing for the specific drugs studied (antidepressants, antidiabetics, drugs against osteoporosis and lipid-lowering drugs) and early discontinuation (r = 0.29 -0.44), but not for anti-hypertensive drugs. The analysis of the association between prevalence...

  10. Early literacy

    DEFF Research Database (Denmark)

    Jensen, Anders Skriver

    2012-01-01

    This paper discusses findings from the Danish contribution to the EASE project, a European research project running from 2008 to 2010 on early literacy in relation to the transition from childcare to school. It explores a holistic, inclusive approach to early literacy that resists a narrow...... and schools. The paper also draws on Gee’s (2001, 2003, 2004, 2008) sociocultural approach to literacy, and Honneth’s (2003, 2006) concept of recognition. Emphasizing participation and recognition as key elements, it claims that stakeholders in early liter- acy must pay attention to how diverse early literacy...... opportunities empower children, especially when these opportunities are employed in a project-based learning environ- ment in which each child is able to contribute to the shared literacy events....

  11. High-grade iron ore at Windarling, Yilgarn Craton: a product of syn-orogenic deformation, hypogene hydrothermal alteration and supergene modification in an Archean BIF-basalt lithostratigraphy

    Science.gov (United States)

    Angerer, Thomas; Hagemann, Steffen G.; Danyushevsky, Leonid

    2013-08-01

    Banded iron formation (BIF)-hosted iron ore deposits in the Windarling Range are located in the lower greenstone succession of the Marda-Diemals greenstone belt, Southern Cross domain, Yilgarn Craton and constitute a total hematite-martite-goethite ore resource of minimum 52 Mt at 60 wt.% Fe (0.07 P). Banded iron formation is interlayered with high-Mg basalts at Windarling and precipitated during episodes of volcanic quiescence. Trace element content and the rare earth element (REE) ratios Y/Ho (42 to 45), Sm/Yb (1.5), together with positive La and Gd anomalies in `least-altered' hematite-magnetite-metachert-BIF indicate the precipitation from Archean seawater that was fertilised by hydrothermal vent fluids with a basaltic HREE-Y signature. Hypogene iron ore in sub-greenschist facies metamorphosed BIF formed during three distinct stages: ore stage 1 was a syn- to post-metamorphic, syn-D1, Fe-Ca-Mg-Ni-Co-P-REE metasomatism that produced local Ni-REE-rich Fe-dolomite-magnetite alteration in BIF. Hydrothermal alteration was induced by hot fluid flow controlled by brittle-ductile reactivation of BIF-basalt margins and crosscutting D1 faults. The Ni-Co-rich content of dolomite and a shift in REE ratios in carbonate-altered BIF towards Archean mafic rock signature (Y/Ho to 31 to 40, Sm/Yb to 1 to 2 and Gd/Gd* to 1.2 to 1.4) suggest that high-Mg basalts in the Windarling Range were the primary source of introduced metals. During ore stage 2, a syn-deformational and likely acidic and oxidised fluid flow along BIF-basalt margins and within D1 faults leached carbonate and precipitated lepidoblastic and anhedral/granoblastic hematite. High-grade magnetite-hematite ore is formed during this stage. Ore stage 3 hydrothermal specular hematite (spcH)-Fe-dolomite-quartz alteration was controlled by a late-orogenic, brittle, compressional/transpressional stage (D4; the regional-scale shear-zone-related D3 is not preserved in Windarling). This minor event remobilised iron oxides

  12. Reactivation of the Archean-Proterozoic suture along the southern margin of Laurentia during the Mazatzal orogeny: Petrogenesis and tectonic implications of ca. 1.63 Ga granite in southeastern Wyoming

    Science.gov (United States)

    Jones, Daniel S.; Barnes, Calvin G.; Premo, Wayne R.; Snoke, Arthur W.

    2013-01-01

    The presence of ca. 1.63 Ga monzogranite (the “white quartz monzonite”) in the southern Sierra Madre, southeastern Wyoming, is anomalous given its distance from the nearest documented plutons of similar age (central Colorado) and the nearest contemporaneous tectonic margin (New Mexico). It is located immediately south of the Cheyenne belt—a ca. 1.75 Ga Archean-Proterozoic tectonic suture. New geochronological, isotopic, and geochemical data suggest that emplacement of the white quartz monzonite occurred between ca. 1645 and 1628 Ma (main pulse ca. 1628 Ma) and that the white quartz monzonite originated primarily by partial melting of the Big Creek Gneiss, a modified arc complex. There is no evidence that mafic magmas were involved. Open folds of the ca. 1750 Ma regional foliation are cut by undeformed white quartz monzonite. On a regional scale, rocks intruded by the white quartz monzonite have experienced higher pressure and temperature conditions and are migmatitic as compared to the surrounding rocks, suggesting a genetic relationship between the white quartz monzonite and tectonic exhumation. We propose that regional shortening imbricated the Big Creek Gneiss, uplifting the now-exposed high-grade rocks of the Big Creek Gneiss (hanging wall of the thrust and wall rock to the white quartz monzonite) and burying correlative rocks, which partially melted to form the white quartz monzonite. This tectonism is attributed to the ca. 1.65 Ga Mazatzal orogeny, as foreland shortening spread progressively into the Yavapai Province. Mazatzal foreland effects have also been described in the Great Lakes region and have been inferred in the Black Hills of South Dakota. We suggest that the crustal-scale rheologic contrast across the Archean-Proterozoic suture, originally developed along the southern margin of Laurentia, and including the Cheyenne belt, facilitated widespread reactivation of that boundary during the Mazatzal orogeny. This finding emphasizes the degree to

  13. Early Math.

    Science.gov (United States)

    Van Nuys, Ute Elisabeth

    1986-01-01

    Presents reviews of the following mathematics software designed to teach young children counting, number recognition, visual discrimination, matching, addition, and subtraction skills; Stickybear Numbers, Learning with Leeper, Getting Ready to Read and Add, Counting Parade, Early Games for Young Children, Charlie Brown's 1,2,3's, Let's Go Fishing,…

  14. Constraining the climate and ocean pH of the early Earth with a geological carbon cycle model

    Science.gov (United States)

    Krissansen-Totton, Joshua; Arney, Giada N.; Catling, David C.

    2018-04-01

    The early Earth’s environment is controversial. Climatic estimates range from hot to glacial, and inferred marine pH spans strongly alkaline to acidic. Better understanding of early climate and ocean chemistry would improve our knowledge of the origin of life and its coevolution with the environment. Here, we use a geological carbon cycle model with ocean chemistry to calculate self-consistent histories of climate and ocean pH. Our carbon cycle model includes an empirically justified temperature and pH dependence of seafloor weathering, allowing the relative importance of continental and seafloor weathering to be evaluated. We find that the Archean climate was likely temperate (0–50 °C) due to the combined negative feedbacks of continental and seafloor weathering. Ocean pH evolves monotonically from 6.6‑0.4+0.6 (2σ) at 4.0 Ga to 7.0‑0.5+0.7 (2σ) at the Archean–Proterozoic boundary, and to 7.9‑0.2+0.1 (2σ) at the Proterozoic–Phanerozoic boundary. This evolution is driven by the secular decline of pCO2, which in turn is a consequence of increasing solar luminosity, but is moderated by carbonate alkalinity delivered from continental and seafloor weathering. Archean seafloor weathering may have been a comparable carbon sink to continental weathering, but is less dominant than previously assumed, and would not have induced global glaciation. We show how these conclusions are robust to a wide range of scenarios for continental growth, internal heat flow evolution and outgassing history, greenhouse gas abundances, and changes in the biotic enhancement of weathering.

  15. Re-Os systematics of komatiites and komatiitic basalts at Dundonald Beach, Ontario, Canada: Evidence for a complex alteration history and implications of a late-Archean chondritic mantle source

    Science.gov (United States)

    Gangopadhyay, Amitava; Sproule, Rebecca A.; Walker, Richard J.; Lesher, C. Michael

    2005-11-01

    Osmium isotopic compositions, and Re and Os concentrations have been examined in one komatiite unit and two komatiitic basalt units at Dundonald Beach, part of the 2.7 Ga Kidd-Munro volcanic assemblage in the Abitibi greenstone belt, Ontario, Canada. The komatiitic rocks in this locality record at least three episodes of alteration of Re-Os elemental and isotope systematics. First, an average of 40% and as much as 75% Re may have been lost due to shallow degassing during eruption and/or hydrothermal leaching during or immediately after emplacement. Second, the Re-Os isotope systematics of whole rock samples with 187Re/ 188Os ratios >1 were reset at ˜2.5 Ga, possibly due to a regional metamorphic event. Third, there is evidence for relatively recent gain and loss of Re in some rocks. Despite the open-system behavior, some aspects of the Re-Os systematics of these rocks can be deciphered. The bulk distribution coefficient for Os (D Ossolid/liquid) for the Dundonald rocks is ˜3 ± 1 and is well within the estimated D values obtained for komatiites from the nearby Alexo area and stratigraphically-equivalent komatiites from Munro Township. This suggests that Os was moderately compatible during crystal-liquid fractionation of the magmas parental to the Kidd-Munro komatiitic rocks. Whole-rock samples and chromite separates with low 187Re/ 188Os ratios (Gorgona Island, arc-related rocks and present-day ocean island basalts. This suggests that the Kidd-Munro komatiites sampled a late-Archean mantle source region that was significantly more homogeneous with respect to Re/Os relative to most modern mantle-derived rocks.

  16. Early Evolution of Earth's Geochemical Cycle and Biosphere: Implications for Mars Exobiology

    Science.gov (United States)

    DesMarais, David J.; Chang, Sherwood (Technical Monitor)

    1997-01-01

    Carbon (C) has played multiple key roles for life and its environment. C has formed organics, greenhouse gases, aquatic pH buffers, redox buffers, and magmatic constituents affecting plutonism and volcanism. These roles interacted across a network of reservoirs and processes known as the biogeochemical C cycle. Changes in the cycle over geologic time were driven by increasing solar luminosity, declining planetary heat flow, and continental and biological evolution. The early Archean C cycle was dominated by hydrothermal alteration of crustal rocks and by thermal emanations of CO2 and reduced species (eg., H2, Fe(2+) and sulfides). Bioorganic synthesis was achieved by nonphotosynthetic CO2-fixing bacteria (chemoautotrophs) and, possibly, bacteria (organotrophs) utilizing any available nonbiological organic C. Responding both to abundant solar energy and to a longterm decline in thermal sources of chemical energy and reducing power, the blaspheme first developed anoxygenic photosynthesis, then, ultimately, oxygenic photosynthesis. O2-photosynthesis played a central role in transforming the ancient environment and blaspheme to the modem world. The geochemical C cycles of early Earth and Mars were quite similar. The principal differences between the modem C cycles of these planets arose during the later evolution of their heat flows, crusts, atmospheres and, perhaps, their blasphemes.

  17. The Early History of Life

    Science.gov (United States)

    Nisbet, E. G.; Fowler, C. M. R.

    2003-12-01

    The youth of the Earth is strange to us. Many of the most fundamental constraints on life may have been different, especially the oxidation state of the surface. Should we suddenly land on its Hadean or early Archean surface by some sci-fi accident, we would not recognize our home. Above, the sky may have been green or some other unworldly color, and above that the weak young Sun might have been unrecognizable to someone trying to identify it from its spectrum. Below, seismology would show a hot, comparatively low-viscosity interior, possibly with a magma ocean in the deeper part of the upper mantle (Drake and Righter, 2002; Nisbet and Walker, 1982), and a core that, though present, was perhaps rather smaller than today. The continents may have been small islands in an icy sea, mostly frozen with some leads of open water, ( Sleep et al., 2001). Into these icy oceans, huge protruding Hawaii-like volcanoes would have poured out vast far-spreading floods of komatiite lavas in immense eruptions that may have created sudden local hypercane storms to disrupt the nearby icebergs. And meteorites would rain down.Or perhaps it was not so strange, nor so violent. The child is father to the man; young Earth was mother to Old Earth. Earth had hydrogen, silicate rock below and on the surface abundant carbon, which her ancient self retains today. Moreover, Earth was oxygen-rich, as today. Today, a tiny part of the oxygen is free, as air; then the oxygen would have been in the mantle while the surface oxygen was used to handcuff the hydrogen as dihydrogen monoxide. Oxygen dihydride is dense, unlikely to fly off to space, and at the poles, rock-forming. Of all the geochemical features that make Earth unique, the initial degassing (Genesis 2 : b) and then the sustained presence of liquid water is the defining oddity of this planet. Early Earth probably also kept much of its carbon, nitrogen, and sulfur as oxide or hydride. And, after the most cataclysmic events had passed, ˜4.5 Ga

  18. Coupled Nd-142, Nd-143 and Hf-176 Isotopic Data from 3.6-3.9 Ga Rocks: New Constraints on the Timing of Early Terrestrial Chemical Reservoirs

    Science.gov (United States)

    Bennett, Vickie C.; Brandon, alan D.; Hiess, Joe; Nutman, Allen P.

    2007-01-01

    Increasingly precise data from a range of isotopic decay schemes, including now extinct parent isotopes, from samples of the Earth, Mars, Moon and meteorites are rapidly revising our views of early planetary differentiation. Recognising Nd-142 isotopic variations in terrestrial rocks (which can only arise from events occurring during the lifetime of now extinct Sm-146 [t(sub 1/2)=103 myr]) has been an on-going quest starting with Harper and Jacobsen. The significance of Nd-142 variations is that they unequivocally reflect early silicate differentiation processes operating in the first 500 myr of Earth history, the key time period between accretion and the beginning of the rock record. The recent establishment of the existence of Nd-142 variations in ancient Earth materials has opened a new range of questions including, how widespread is the evidence of early differentiation, how do Nd-142 compositions vary with time, rock type and geographic setting, and, combined with other types of isotopic and geochemical data, what can Nd-142 isotopic variations reveal about the timing and mechanisms of early terrestrial differentiation? To explore these questions we are determining high precision Nd-142, Nd-143 and Hf-176 isotopic compositions from the oldest well preserved (3.63- 3.87 Ga), rock suites from the extensive early Archean terranes of southwest Greenland and western Australia.

  19. Archean crust-mantle geochemical differentiation

    Science.gov (United States)

    Tilton, G. R.

    Isotope measurements on carbonatite complexes and komatiites can provide information on the geochemical character and geochemical evolution of the mantle, including the sub-continental mantle. Measurements on young samples establish the validity of the method. These are based on Sr, Nd and Pb data from the Tertiary-Mesozoic Gorgona komatiite and Sr and Pb data from the Cretaceous Oka carbonatite complex. In both cases the data describe a LIL element-depleted source similar to that observed presently in MORB. Carbonatite data have been used to study the mantle beneath the Superior Province of the Canadian Shield one billion years (1 AE) ago. The framework for this investigation was established by Bell et al., who showed that large areas of the province appear to be underlain by LIL element-depleted mantle (Sr-85/Sr-86=0.7028) at 1 AE ago. Additionally Bell et al. found four complexes to have higher initial Sr ratios (Sr-87/Sr-86=0.7038), which they correlated with less depleted (bulk earth?) mantle sources, or possibly crustal contamination. Pb isotope relationships in four of the complexes have been studied by Bell et al.

  20. Archean crust-mantle geochemical differentiation

    Science.gov (United States)

    Tilton, G. R.

    1983-01-01

    Isotope measurements on carbonatite complexes and komatiites can provide information on the geochemical character and geochemical evolution of the mantle, including the sub-continental mantle. Measurements on young samples establish the validity of the method. These are based on Sr, Nd and Pb data from the Tertiary-Mesozoic Gorgona komatiite and Sr and Pb data from the Cretaceous Oka carbonatite complex. In both cases the data describe a LIL element-depleted source similar to that observed presently in MORB. Carbonatite data have been used to study the mantle beneath the Superior Province of the Canadian Shield one billion years (1 AE) ago. The framework for this investigation was established by Bell et al., who showed that large areas of the province appear to be underlain by LIL element-depleted mantle (Sr-85/Sr-86=0.7028) at 1 AE ago. Additionally Bell et al. found four complexes to have higher initial Sr ratios (Sr-87/Sr-86=0.7038), which they correlated with less depleted (bulk earth?) mantle sources, or possibly crustal contamination. Pb isotope relationships in four of the complexes have been studied by Bell et al.

  1. Early or Premature Menopause

    Science.gov (United States)

    ... email updates Enter email Submit Early or premature menopause Menopause that happens before age 40 is called ... What is the difference between early and premature menopause? Early or premature menopause happens when ovaries stop ...

  2. Early hospital discharge and early puerperal complications.

    Science.gov (United States)

    Ramírez-Villalobos, Dolores; Hernández-Garduño, Adolfo; Salinas, Aarón; González, Dolores; Walker, Dilys; Rojo-Herrera, Guadalupe; Hernández-Prado, Bernardo

    2009-01-01

    To evaluate the association between time of postpartum discharge and symptoms indicative of complications during the first postpartum week. Women with vaginal delivery at a Mexico City public hospital, without complications before the hospital discharge, were interviewed seven days after delivery. Time of postpartum discharge was classified as early (25 hours). The dependent variable was defined as the occurrence and severity of puerperal complication symptoms. Out of 303 women, 208 (68%) were discharged early. However, women with early discharge and satisfactory prenatal care had lower odds of presenting symptoms in early puerperium than women without early discharge and inadequate prenatal care (OR 0.36; 95% confidence intervals = 0.17-0.76). There was no association between early discharge and symptoms of complications during the first postpartum week; the odds of complications were lower for mothers with early discharge and satisfactory prenatal care.

  3. Evolving Oxygen Landscape of the Early Atmosphere and Oceans

    Science.gov (United States)

    Lyons, T. W.; Reinhard, C. T.; Planavsky, N. J.

    2013-12-01

    The past decade has witnessed remarkable advances in our understanding of oxygen on the early Earth, and a new framework, the topic of this presentation, is now in place to address the controls on spatiotemporal distributions of oxygen and their potential relationships to deep-Earth processes. Recent challenges to the Archean biomarker record have put an added burden on inorganic geochemistry to fingerprint and quantify the early production, accumulation, and variation of biospheric oxygen. Fortunately, a wide variety of techniques now point convincingly to photosynthetic oxygen production and dynamic accumulation well before the canonical Great Oxidation Event (GOE). Recent modeling of sulfur recycling over this interval allows for transient oxygen accumulation in the atmosphere without the disappearance of non-mass-dependent (NMD) sulfur isotope anomalies from the stratigraphic record and further allows for persistent accumulation in the atmosphere well before the permanent disappearance of NMD signals. This recent work suggests that the initial rise of oxygen may have occurred in fits and starts rather than a single step, and that once permanently present in the atmosphere, oxygen likely rose to high levels and then plummeted, in phase with the Paleoproterozoic Lomagundi positive carbon isotope excursion. More than a billion years of oxygen-free conditions in the deep ocean followed and set a challenging course for life, including limited abundances and diversity of eukaryotic organisms. Despite this widespread anoxia, sulfidic (euxinic) conditions were likely limited to productive ocean margins. Nevertheless, euxinia was sufficiently widespread to impact redox-dependent nutrient relationships, particularly the availability of bioessential trace metals critical in the nitrogen cycle, which spawned feedbacks that likely maintained oxygen at very low levels in the ocean and atmosphere and delayed the arrival of animals. Then, in the mid, pre-glacial Neoproterozoic

  4. Petrogenesis of early cretaceous silicic volcanism in SE Uruguay. The role of mantle and crustal sources

    International Nuclear Information System (INIS)

    Lustrino, Michele; Morbidelli, Lucio; Marrazzo, Marianna; Melluso, Leone; Brotzu, Pietro; Tassinari, Colombo C.G.; Gomes, Celso B.; Ruberti, Excelso

    2010-01-01

    Early Cretaceous (∼129 Ma) silicic rocks crop out in SE Uruguay between the Laguna Merin and Santa Lucia basins in the Lascano, Sierra Sao Miguel, Salamanca and Minas areas. They are mostly rhyolites with minor quartz-trachytes and are nearly contemporaneous with the Parana-Etendeka igneous province and with the first stages of South Atlantic Ocean opening. A strong geochemical variability (particularly evident from Rb/Nb, Nb/Y trace element ratios) and a wide range of Sr-Nd isotopic ratios ( 143 Nd/ 144 Nd (129) =0.51178-0.51209; 87 Sr/ 86 Sr (129) =0.70840-0.72417) characterize these rocks. Geochemistry allows to distinguish two compositional groups, corresponding to the north-eastern (Lascano and Sierra Sao Miguel, emplaced on the Neo-Proterozoic southern sector of the Dom Feliciano mobile belt) and south-eastern localities (Salamanca, Minas, emplaced on the much older (Archean) Nico Perez terrane or on the boundary between the Dom Feliciano and Nico Perez terranes). These compositional differences between the two groups are explained by variable mantle source and crust contributions. The origin of the silicic magmas is best explained by complex processes involving assimilation and fractional crystallization and mixing of a basaltic magma with upper crustal lithologies, for Lascano and Sierra Sao Miguel rhyolites. In the Salamanca and Minas rocks genesis, a stronger contribution from lower crust is indicated. (author)

  5. A morphogram for silica-witherite biomorphs and its application to microfossil identification in the early earth rock record.

    Science.gov (United States)

    Rouillard, J; García-Ruiz, J-M; Gong, J; van Zuilen, M A

    2018-05-01

    Archean hydrothermal environments formed a likely site for the origin and early evolution of life. These are also the settings, however, were complex abiologic structures can form. Low-temperature serpentinization of ultramafic crust can generate alkaline, silica-saturated fluids in which carbonate-silica crystalline aggregates with life-like morphologies can self-assemble. These "biomorphs" could have adsorbed hydrocarbons from Fischer-Tropsch type synthesis processes, leading to metamorphosed structures that resemble carbonaceous microfossils. Although this abiogenic process has been extensively cited in the literature and has generated important controversy, so far only one specific biomorph type with a filamentous shape has been discussed for the interpretation of Archean microfossils. It is therefore critical to precisely determine the full distribution in morphology and size of these biomorphs, and to study the range of plausible geochemical conditions under which these microstructures can form. Here, a set of witherite-silica biomorph synthesis experiments in silica-saturated solutions is presented, for a range of pH values (from 9 to 11.5) and barium ion concentrations (from 0.6 to 40 mmol/L BaCl 2 ). Under these varying conditions, a wide range of life-like structures is found, from fractal dendrites to complex shapes with continuous curvature. The size, spatial concentration, and morphology of the biomorphs are strongly controlled by environmental parameters, among which pH is the most important. This potentially limits the diversity of environments in which the growth of biomorphs could have occurred on Early Earth. Given the variety of the observed biomorph morphologies, our results show that the morphology of an individual microstructure is a poor criterion for biogenicity. However, biomorphs may be distinguished from actual populations of cellular microfossils by their wide, unimodal size distribution. Biomorphs grown by diffusion in silica gel can

  6. Early Childhood Systems: Transforming Early Learning

    Science.gov (United States)

    Kagan, Sharon Lynn, Ed.; Kauertz, Kristie, Ed.

    2012-01-01

    In this seminal volume, leading authorities strategize about how to create early childhood systems that transcend politics and economics to serve the needs of all young children. The authors offer different interpretations of the nature of early childhood systems, discuss the elements necessary to support their development, and examine how…

  7. Microbes, Mineral Evolution, and the Rise of Microcontinents-Origin and Coevolution of Life with Early Earth.

    Science.gov (United States)

    Grosch, Eugene G; Hazen, Robert M

    2015-10-01

    Earth is the most mineralogically diverse planet in our solar system, the direct consequence of a coevolving geosphere and biosphere. We consider the possibility that a microbial biosphere originated and thrived in the early Hadean-Archean Earth subseafloor environment, with fundamental consequences for the complex evolution and habitability of our planet. In this hypothesis paper, we explore possible venues for the origin of life and the direct consequences of microbially mediated, low-temperature hydrothermal alteration of the early oceanic lithosphere. We hypothesize that subsurface fluid-rock-microbe interactions resulted in more efficient hydration of the early oceanic crust, which in turn promoted bulk melting to produce the first evolved fragments of felsic crust. These evolved magmas most likely included sialic or tonalitic sheets, felsic volcaniclastics, and minor rhyolitic intrusions emplaced in an Iceland-type extensional setting as the earliest microcontinents. With the further development of proto-tectonic processes, these buoyant felsic crustal fragments formed the nucleus of intra-oceanic tonalite-trondhjemite-granitoid (TTG) island arcs. Thus microbes, by facilitating extensive hydrothermal alteration of the earliest oceanic crust through bioalteration, promoted mineral diversification and may have been early architects of surface environments and microcontinents on young Earth. We explore how the possible onset of subseafloor fluid-rock-microbe interactions on early Earth accelerated metavolcanic clay mineral formation, crustal melting, and subsequent metamorphic mineral evolution. We also consider environmental factors supporting this earliest step in geosphere-biosphere coevolution and the implications for habitability and mineral evolution on other rocky planets, such as Mars.

  8. Early discharge following birth

    DEFF Research Database (Denmark)

    Nilsson, Ingrid M. S.; Kronborg, Hanne; Knight, Christopher H.

    2017-01-01

    .26–0.48) and primiparous compared to multiparous had an OR of 0.22 (CI 0.17–0.29) for early discharge. Other predictors for early discharge were: no induction of labour, no epidural painkiller, bleeding less than 500 ml during delivery, higher gestational age, early expected discharge and positive breastfeeding experience...

  9. Early Transcendental Analysis

    OpenAIRE

    Cowell, Simon; Poulin, Philippe

    2015-01-01

    In Early Transcendentals (The American Mathematical Monthly, Vol. 104, No 7) Steven Weintraub presents a rigorous justifcation of the "early transcendental" calculus textbook approach to the exponential and logarithmic functions. However, he uses tools such as term-by-term differentiation of infinite series. We present a rigorous treatment of the early transcendental approach suitable for a first course in analysis, using mainly the supremum property of the real numbers.

  10. Early Retirement Payoff

    Science.gov (United States)

    Fitzpatrick, Maria D.; Lovenheim, Michael F.

    2014-01-01

    As public budgets have grown tighter over the past decade, states and school districts have sought ways to control the growth of spending. One increasingly common strategy employed to rein in costs is to offer experienced teachers with high salaries financial incentives to retire early. Although early retirement incentive (ERI) programs have been…

  11. Early Modern Philosophical Systems

    NARCIS (Netherlands)

    L. van Bunge (Wiep)

    2014-01-01

    textabstractThe occurrence of an entry on early modern philosophical systems in an encyclopaedia of Neo-Latin studies is fraught with complications, if only on account of the gradual disappearance during the early modern period of Latin as the main vehicle of philosophical communication. What

  12. Early Intervention in Budapest.

    Science.gov (United States)

    Gallai, Maria; Katona, Ferenc; Balogh, Erzsebet; Schultheisz, Judit; Deveny, Anna; Borbely, Sjoukje

    2000-01-01

    This article presents five models of early intervention used in Budapest. Diagnostic and treatment methods used by the Pediatric Institute and the Conductive Education System are described, along with the Deveny Special Manual Technique and Gymnastic Method, the Gezenguz method and techniques used in the Early Developmental Center. (CR)

  13. The early universe

    International Nuclear Information System (INIS)

    Steigman, G.

    1989-01-01

    The author discusses the physics of the early universe: the production and survival of relics from the big bang. The author comments on relic WIMPs as the dark matter in the universe. The remainder of this discussion is devoted to a review of the status of the only predictions from the early evolution of the universe that are accessible to astronomical observation: primordial nucleosynthesis

  14. Early College High Schools

    Science.gov (United States)

    Dessoff, Alan

    2011-01-01

    For at-risk students who stand little chance of going to college, or even finishing high school, a growing number of districts have found a solution: Give them an early start in college while they still are in high school. The early college high school (ECHS) movement that began with funding from the Bill and Melinda Gates Foundation 10 years ago…

  15. U/Pb (SHRIMP), {sup 207}Pb/{sup 206}Pb, Rb/Sr, Sm/Nd e K/Ar geochronology of granite-greenstone terrains of Gaviao Block: implications for the Proterozoic and Archean evolution of Sao Francisco Craton, Brazil; Geocronologia U/Pb (SHRIMP), {sup 207}Pb/{sup 206}Pb, Rb/Sr, Sm/Nd e K/Ar dos terrenos granito-greenstone do Bloco do Gaviao: implicacoes para a evolucao arqueana e proterozoica do craton do Sao Francisco, Brasil

    Energy Technology Data Exchange (ETDEWEB)

    Leal, Luiz Rogerio Bastos

    1998-07-01

    The Gaviao Block (GB) in the northern portion of the Sao Francisco Craton-Northeast of Brazil, constitutes one of the oldest Archean fragments of the South American Platform Archean crust. GB underwent several events of juvenile accretion and reworking of continental crust along its evolutionary history, notably between the Archean and the Paleoproterozoic. {sup 207}Pb/{sup 206}Pb isotopic analyses were carried out in two zircons populations from strongly migmatized TTG terranes found in the proximity of Brumado: the first population (7 crystals) is taken as representative of the crystallization period of the TTG terranes at 3300 {+-} 45 Ma; the second (2 crystals) represents the age of the first even of metamorphism/migmatization at 2910 {+-} 10 Ma. {sup 207} Pb/{sup 206} Pb analyses in zircons from an outcrop of non-migmatized TTG in the area yielded a 3202 {+-} 15 Ma age (4 crystals), interpreted to be the crystallization period of the gneiss protolith. Sm/Nd analyses on the TTG rocks of the Brumado region yielded T{sub DM} model ages varying between 3.26 and 3.36 Ga and {epsilon}{sub Nd}{sup (t)} between -3.5 and +0.7. These data suggest the occurrence of juvenile accretions to the continental crust during the Archean, with differential involvement of crustal materials. The geochemical data of rare earth elements corresponding to the TTG terranes revealed moderate LRRE contents (La{sub N}=83,5), low HREE contents (La{sub N}=2,5) and a fairly fractionated pattern (La/Yb){sub N}=34, besides lack of negative Eu anomaly, showing that these rocks have similar compositions to those TTG terranes of cratonic continents, as well as some Archean rocks from CSF (e.g. Sete Voltas, Boa Vista). Finally, the youngest ages present in GB rocks (ca. 1.2-0.45 Ga) represent the role played by tectono thermal events, which produced partial or total rejuvenation of the Rb/Sr and K/Ar isotopic systems during the Espinhaco and Brasiliano cycles. In particular, K/Ar ages illustrate the

  16. Early Option Exercise

    DEFF Research Database (Denmark)

    Heje Pedersen, Lasse; Jensen, Mads Vestergaard

    A classic result by Merton (1973) is that, except just before expiration or dividend payments, one should never exercise a call option and never convert a convertible bond. We show theoretically that this result is overturned when investors face frictions. Early option exercise can be optimal when...... it reduces short-sale costs, transaction costs, or funding costs. We provide consistent empirical evidence, documenting billions of dollars of early exercise for options and convertible bonds using unique data on actual exercise decisions and frictions. Our model can explain as much as 98% of early exercises...

  17. Early Option Exercise

    DEFF Research Database (Denmark)

    Jensen, Mads Vestergaard; Heje Pedersen, Lasse

    2016-01-01

    A classic result by Merton (1973) is that, except just before expiration or dividend payments, one should never exercise a call option and never convert a convertible bond. We show theoretically that this result is overturned when investors face frictions. Early option exercise can be optimal when...... it reduces short-sale costs, transaction costs, or funding costs. We provide consistent empirical evidence, documenting billions of dollars of early exercise for options and convertible bonds using unique data on actual exercise decisions and frictions. Our model can explain as much as 98% of early exercises...

  18. Early detection of psychosis

    DEFF Research Database (Denmark)

    Larsen, Tor Ketil; Melle, Ingrid; Auestad, B.

    2011-01-01

    Background During the last decades we have seen a new focus on early treatment of psychosis. Several reviews have shown that duration of untreated psychosis (DUP) is correlated to better outcome. However, it is still unknown whether early treatment will lead to a better long-term outcome....... This study reports the effects of reducing DUP on 5-year course and outcome. Method During 1997–2000 a total of 281 consecutive patients aged >17 years with first episode non-affective psychosis were recruited, of which 192 participated in the 5-year follow-up. A comprehensive early detection (ED) programme...... and cognitive factors and for global assessment of functioning for social functioning at 5-year follow-up. The ED group also had more contacts with friends. Regression analysis did not find that these differences could be explained by confounders. Conclusions Early treatment had positive effects on clinical...

  19. Early Head Start Evaluation

    Data.gov (United States)

    U.S. Department of Health & Human Services — Longitudinal information from an evaluation where children were randomly assigned to Early Head Start or community services as usual;direct assessments and...

  20. Guideline for Early Interventions

    National Research Council Canada - National Science Library

    Vries, de, Maaike

    2006-01-01

    .... During the last years, the demand for early interventions has been increasing. International literature has shown that the psychosocial effects of disaster and military deployment may last for years...

  1. Early Life Stages

    Science.gov (United States)

    Childhood should be viewed as a sequence of lifestages, from birth through infancy and adolescence. When assessing early life risks, consideration is given to risks resulting from fetal exposure via the pregnant mother, as well as postnatal exposures.

  2. Cancer treatment - early menopause

    Science.gov (United States)

    Premature menopause; Ovarian insufficiency - cancer ... Cancer treatments that can cause early menopause include: Surgery. Having both ovaries removed causes menopause to happen right away. If you are age 50 or younger, your provider may ...

  3. Early intervention in psychosis

    DEFF Research Database (Denmark)

    Csillag, Claudio; Nordentoft, Merete; Mizuno, Masafumi

    2017-01-01

    AIM: Early intervention in psychosis (EIP) is a well-established approach with the intention of early detection and treatment of psychotic disorders. Its clinical and economic benefits are well documented. This paper presents basic aspects of EIP services, discusses challenges to their implementa......AIM: Early intervention in psychosis (EIP) is a well-established approach with the intention of early detection and treatment of psychotic disorders. Its clinical and economic benefits are well documented. This paper presents basic aspects of EIP services, discusses challenges...... benefits alone is not enough to promote implementation, as economic arguments and political and social pressure have shown to be important elements in efforts to achieve implementation. CONCLUSIONS: Users' narratives, close collaboration with community organizations and support from policy-makers and known...

  4. Earth's early biosphere

    Science.gov (United States)

    Des Marais, D. J.

    1998-01-01

    Understanding our own early biosphere is essential to our search for life elsewhere, because life arose on Earth very early and rocky planets shared similar early histories. The biosphere arose before 3.8 Ga ago, was exclusively unicellular and was dominated by hyperthermophiles that utilized chemical sources of energy and employed a range of metabolic pathways for CO2 assimilation. Photosynthesis also arose very early. Oxygenic photosynthesis arose later but still prior to 2.7 Ga. The transition toward the modern global environment was paced by a decline in volcanic and hydrothermal activity. These developments allowed atmospheric O2 levels to increase. The O2 increase created new niches for aerobic life, most notably the more advanced Eukarya that eventually spawned the megascopic fauna and flora of our modern biosphere.

  5. Mercury's Early Geologic History

    Science.gov (United States)

    Denevi, B. W.; Ernst, C. M.; Klima, R. L.; Robinson, M. S.

    2018-05-01

    A combination of geologic mapping, compositional information, and geochemical models are providing a better understanding of Mercury's early geologic history, and allow us to place it in the context of the Moon and the terrestrial planets.

  6. Embracing early literacy indicators

    DEFF Research Database (Denmark)

    Broström, Stig; Hansen, Ole Henrik; Jensen, Anders Skriver

    2010-01-01

    Abstract til paper om early literacy indikatorer. Det paper abstractet er knyttet til var en del af et inviteret, selvorganiseret symposium som afrapporterede EASE-projektet (www.ease-eu.com) på OMEP's 26. verdenskongres.......Abstract til paper om early literacy indikatorer. Det paper abstractet er knyttet til var en del af et inviteret, selvorganiseret symposium som afrapporterede EASE-projektet (www.ease-eu.com) på OMEP's 26. verdenskongres....

  7. Who Gets Early Tracheostomy?

    Science.gov (United States)

    Shaw, Joshua J.

    2015-01-01

    BACKGROUND: Although the benefits of early tracheostomy in patients dependent on ventilators are well established, the reasons for variation in time from intubation to tracheostomy remain unclear. We identified clinical and demographic disparities in time to tracheostomy. METHODS: We performed a level 3 retrospective prognostic study by querying the University HealthSystem Consortium (2007-2010) for adult patients receiving a tracheostomy after initial intubation. Time to tracheostomy was designated early ( 10 days). Cohorts were stratified by time to tracheostomy and compared using univariate tests of association and multivariable adjusted models. RESULTS: A total of 49,191 patients underwent tracheostomy after initial intubation: 42% early (n = 21,029) and 58% late (n = 28,162). On both univariate and multivariable analyses, women, blacks, Hispanics, and patients receiving Medicaid were less likely to receive an early tracheostomy. Patients in the early group also experienced lower rates of mortality (OR, 0.84; 95% CI, 0.79-0.88). CONCLUSIONS: Early tracheostomy was associated with increased survival. Yet, there were still significant disparities in time to tracheostomy according to sex, race, and type of insurance. Application of evidence-based algorithms for tracheostomy may reduce unequal treatment and improve overall mortality rates. Additional research into this apparent bias in referral/rendering of tracheostomy is needed. PMID:26313324

  8. Redefining early gastric cancer.

    Science.gov (United States)

    Barreto, Savio G; Windsor, John A

    2016-01-01

    The problem is that current definitions of early gastric cancer allow the inclusion of regional lymph node metastases. The increasing use of endoscopic submucosal dissection to treat early gastric cancer is a concern because regional lymph nodes are not addressed. The aim of the study was thus to critically evaluate current evidence with regard to tumour-specific factors associated with lymph node metastases in "early gastric cancer" to develop a more precise definition and improve clinical management. A systematic and comprehensive search of major reference databases (MEDLINE, EMBASE, PubMed and the Cochrane Library) was undertaken using a combination of text words "early gastric cancer", "lymph node metastasis", "factors", "endoscopy", "surgery", "lymphadenectomy" "mucosa", "submucosa", "lymphovascular invasion", "differentiated", "undifferentiated" and "ulcer". All available publications that described tumour-related factors associated with lymph node metastases in early gastric cancer were included. The initial search yielded 1494 studies, of which 42 studies were included in the final analysis. Over time, the definition of early gastric cancer has broadened and the indications for endoscopic treatment have widened. The mean frequency of lymph node metastases increased on the basis of depth of infiltration (mucosa 6% vs. submucosa 28%), presence of lymphovascular invasion (absence 9% vs. presence 53%), tumour differentiation (differentiated 13% vs. undifferentiated 34%) and macroscopic type (elevated 13% vs. flat 26%) and tumour diameter (≤2 cm 8% vs. >2 cm 25%). There is a need to re-examine the diagnosis and staging of early gastric cancer to ensure that patients with one or more identifiable risk factor for lymph node metastases are not denied appropriate chemotherapy and surgical resection.

  9. Early Dementia Screening

    Directory of Open Access Journals (Sweden)

    Peter K. Panegyres

    2016-01-01

    Full Text Available As the population of the world increases, there will be larger numbers of people with dementia and an emerging need for prompt diagnosis and treatment. Early dementia screening is the process by which a patient who might be in the prodromal phases of a dementing illness is determined as having, or not having, the hallmarks of a neurodegenerative condition. The concepts of mild cognitive impairment, or mild neurocognitive disorder, are useful in analyzing the patient in the prodromal phase of a dementing disease; however, the transformation to dementia may be as low as 10% per annum. The search for early dementia requires a comprehensive clinical evaluation, cognitive assessment, determination of functional status, corroborative history and imaging (including MRI, FDG-PET and maybe amyloid PET, cerebrospinal fluid (CSF examination assaying Aβ1–42, T-τ and P-τ might also be helpful. Primary care physicians are fundamental in the screening process and are vital in initiating specialist investigation and treatment. Early dementia screening is especially important in an age where there is a search for disease modifying therapies, where there is mounting evidence that treatment, if given early, might influence the natural history—hence the need for cost-effective screening measures for early dementia.

  10. Early cosmology constrained

    Energy Technology Data Exchange (ETDEWEB)

    Verde, Licia; Jimenez, Raul [Institute of Cosmos Sciences, University of Barcelona, IEEC-UB, Martí Franquès, 1, E08028 Barcelona (Spain); Bellini, Emilio [University of Oxford, Denys Wilkinson Building, Keble Road, Oxford, OX1 3RH (United Kingdom); Pigozzo, Cassio [Instituto de Física, Universidade Federal da Bahia, Salvador, BA (Brazil); Heavens, Alan F., E-mail: liciaverde@icc.ub.edu, E-mail: emilio.bellini@physics.ox.ac.uk, E-mail: cpigozzo@ufba.br, E-mail: a.heavens@imperial.ac.uk, E-mail: raul.jimenez@icc.ub.edu [Imperial Centre for Inference and Cosmology (ICIC), Imperial College, Blackett Laboratory, Prince Consort Road, London SW7 2AZ (United Kingdom)

    2017-04-01

    We investigate our knowledge of early universe cosmology by exploring how much additional energy density can be placed in different components beyond those in the ΛCDM model. To do this we use a method to separate early- and late-universe information enclosed in observational data, thus markedly reducing the model-dependency of the conclusions. We find that the 95% credibility regions for extra energy components of the early universe at recombination are: non-accelerating additional fluid density parameter Ω{sub MR} < 0.006 and extra radiation parameterised as extra effective neutrino species 2.3 < N {sub eff} < 3.2 when imposing flatness. Our constraints thus show that even when analyzing the data in this largely model-independent way, the possibility of hiding extra energy components beyond ΛCDM in the early universe is seriously constrained by current observations. We also find that the standard ruler, the sound horizon at radiation drag, can be well determined in a way that does not depend on late-time Universe assumptions, but depends strongly on early-time physics and in particular on additional components that behave like radiation. We find that the standard ruler length determined in this way is r {sub s} = 147.4 ± 0.7 Mpc if the radiation and neutrino components are standard, but the uncertainty increases by an order of magnitude when non-standard dark radiation components are allowed, to r {sub s} = 150 ± 5 Mpc.

  11. Early Islamic Syria

    DEFF Research Database (Denmark)

    Walmsley, Alan

    After more than a century of neglect, a profound revolution is occurring in the way archaeology addresses and interprets developments in the social history of early Islamic Syria-Palestine. This concise book offers an innovative assessment of social and economic developments in Syria-Palestine sh......After more than a century of neglect, a profound revolution is occurring in the way archaeology addresses and interprets developments in the social history of early Islamic Syria-Palestine. This concise book offers an innovative assessment of social and economic developments in Syria......-Palestine shortly before, and in the two centuries after, the Islamic expansion (the later sixth to the early ninth century AD), drawing on a wide range of new evidence from recent archaeological work. Alan Walmsley challenges conventional explanations for social change with the arrival of Islam, arguing...

  12. Early breastfeeding problems

    DEFF Research Database (Denmark)

    Feenstra, Maria Monberg; Kirkeby, Mette Jørgine; Thygesen, Marianne

    2018-01-01

    Objectives Breastfeeding problems are common and associated with early cessation. Stilllength of postpartum hospital stay has been reduced. This leaves new mothers to establish breastfeeding at home with less support from health care professionals. The objective was to explore mothers’ perspectives...... on when breastfeeding problems were the most challenging and prominent early postnatal. The aim was also toidentify possible factors associated with the breastfeeding problems. Methods In a cross-sectional study, a mixed method approach was used to analyse postal survey data from 1437 mothers with full...... term singleton infants. Content analysis was used to analyse mothers’ open text descriptions of their most challenging breastfeeding problem. Multiple logistic regression was used to calculate odds ratios for early breastfeeding problems according to sociodemographic- and psychosocial factors. Results...

  13. Early Intervention in Psychosis

    Science.gov (United States)

    McGorry, Patrick D.

    2015-01-01

    Abstract Early intervention for potentially serious disorder is a fundamental feature of healthcare across the spectrum of physical illness. It has been a major factor in the reductions in morbidity and mortality that have been achieved in some of the non-communicable diseases, notably cancer and cardiovascular disease. Over the past two decades, an international collaborative effort has been mounted to build the evidence and the capacity for early intervention in the psychotic disorders, notably schizophrenia, where for so long deep pessimism had reigned. The origins and rapid development of early intervention in psychosis are described from a personal and Australian perspective. This uniquely evidence-informed, evidence-building and cost-effective reform provides a blueprint and launch pad to radically change the wider landscape of mental health care and dissolve many of the barriers that have constrained progress for so long. PMID:25919380

  14. Early life vaccination

    DEFF Research Database (Denmark)

    Nazerai, Loulieta; Bassi, Maria Rosaria; Uddbäck, Ida Elin Maria

    2016-01-01

    Intracellular pathogens represent a serious threat during early life. Importantly, even though the immune system of newborns may be characterized as developmentally immature, with a propensity to develop Th2 immunity, significant CD8+ T-cell responses may still be elicited in the context of optimal...... the first period of life and provide a pertinent alternative in infant vaccinology. To address this, infant mice were vaccinated with three different adenoviral vectors and the CD8+ T-cell response after early life vaccination was explored. We assessed the frequency, polyfunctionality and in vivo...... cytotoxicity of the elicited memory CD8+ T cells, as well as the potential of these cells to respond to secondary infections and confer protection. We further tested the impact of maternal immunity against our replication-deficient adenoviral vector during early life vaccination. Overall, our results indicate...

  15. Early anaerobic metabolisms

    DEFF Research Database (Denmark)

    Canfield, Donald Eugene; Rosing, Minik T; Bjerrum, Christian

    2006-01-01

    probably driven by the cycling of H2 and Fe2+ through primary production conducted by anoxygenic phototrophs. Interesting and dynamic ecosystems would have also been driven by the microbial cycling of sulphur and nitrogen species, but their activity levels were probably not so great. Despite the diversity......Before the advent of oxygenic photosynthesis, the biosphere was driven by anaerobic metabolisms. We catalogue and quantify the source strengths of the most probable electron donors and electron acceptors that would have been available to fuel early-Earth ecosystems. The most active ecosystems were...... of potential early ecosystems, rates of primary production in the early-Earth anaerobic biosphere were probably well below those rates observed in the marine environment. We shift our attention to the Earth environment at 3.8Gyr ago, where the earliest marine sediments are preserved. We calculate, consistent...

  16. Late Cambrian - Early Ordovician turbidites of Gorny Altai (Russia): Compositions, sources, deposition settings, and tectonic implications

    Science.gov (United States)

    Kruk, Nikolai N.; Kuibida, Yana V.; Shokalsky, Sergey P.; Kiselev, Vladimir I.; Gusev, Nikolay I.

    2018-06-01

    The Cambrian-Ordovician transition was the time of several key events in the history of Central Asia. They were the accretion of Mariana-type island arc systems to the Siberian continent, the related large-scale orogeny and intrusions of basaltic and granitic magma and the formation of a huge turbidite basin commensurate with the Bengal Gulf basin in the western part of the Central Asian orogenic belt (CAOB). The structure of the basin, as well as the sources and environments of deposition remain open to discussion. This paper presents new major- and trace-element data on Late-Cambrian-Early Ordovician turbidites from different parts of the Russian Altai and a synthesis of Nd isotope composition and ages of detrital zircons. The turbidites share chemical similarity with material shed from weathered continental arcs. Broad variations of CIA (39-73) and ICV (0.63-1.66) signatures in sandstones suggest origin from diverse sources and absence of significant sorting. Trace elements vary considerably and have generally similar patterns in rocks from different terranes. On the other hand, there are at least two provinces according to Nd isotope composition and age of detrital zircons. Samples from eastern Russian Altai contain only Phanerozoic zircons and have Nd isotope ratios similar to those in Early Cambrian island arcs (εNdt + 4.4… + 5.4; TNd(DM)-2-st = 0.8-0.9 Ga). Samples from central, western, and southern parts of Russian Altai contain Precambrian zircons (some as old as Late Archean) and have a less radiogenic Nd composition (εNdt up to -3.6; TNd(DM)-2-st up to 1.5 Ga). The chemical signatures of Late Cambrian to Early Ordovician turbidites indicate a provenance chemically more mature than the island arc rocks, and the presence of zircons with 510-490 Ma ages disproves their genetic relation with island arcs. The turbidite basin formed simultaneously with peaks of granitic and alkali-basaltic magmatism in the western Central Asian orogen and resulted from

  17. The Janus face of iron on anoxic worlds: iron oxides are both protective and destructive to life on the early Earth and present-day Mars.

    Science.gov (United States)

    Wadsworth, Jennifer; Cockell, Charles S

    2017-05-01

    The surface of the early Earth was probably subjected to a higher flux of ultraviolet (UV) radiation than today. UV radiation is known to severely damage DNA and other key molecules of life. Using a liquid culture and a rock analogue system, we investigated the interplay of protective and deleterious effects of iron oxides under UV radiation on the viability of the model organism, Bacillus subtilis. In the presence of hydrogen peroxide, there exists a fine balance between iron oxide's protective effects against this radiation and its deleterious effects caused by Photo-Fenton reactions. The maximum damage was caused by a concentration of hematite of ∼1 mg/mL. Concentrations above this confer increasing protection by physical blockage of the UV radiation, concentrations below this cause less effective UV radiation blockage, but also a correspondingly less effective Photo-Fenton reaction, providing an overall advantage. These results show that on anoxic worlds, surface habitability under a high UV flux leaves life precariously poised between the beneficial and deleterious effects of iron oxides. These results have relevance to the Archean Earth, but also the habitability of the Martian surface, where high levels of UV radiation in combination with iron oxides and hydrogen peroxide can be found. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  18. Planetary biology and microbial ecology. Biochemistry of carbon and early life

    Science.gov (United States)

    Margulis, L. (Editor); Nealson, K. H. (Editor); Taylor, I. (Editor)

    1983-01-01

    Experiments made with cyanobacteria, phototrophic bacteria, and methanogenic bacteria are detailed. Significant carbon isotope fractionation data is included. Taken from well documented extant microbial communities, this data provides a basis of comparison for isotope fractionation values measured in Archean and Proterozoic (preCambrian) rocks. Media, methods, and techniques used to acquire data are also described.

  19. 75 FR 20830 - Early Learning

    Science.gov (United States)

    2010-04-21

    ... DEPARTMENT OF EDUCATION Early Learning AGENCY: Office of the Secretary, Department of Education... meetings and written submissions, is seeking input from State agencies responsible for early learning and... assistance providers, researchers of early learning, stakeholders who work with early learning and...

  20. Cognitive Development in Early Readers.

    Science.gov (United States)

    Briggs, Chari; Elkind, David

    Some studies of early readers are discussed. It is pointed out that study of early readers has relevance for practical and theoretical issues in psychology and education. Of interest in this document are the following questions: (1) Are there any special talents or traits distinguishing early from non-early readers? (2) Do children who read early…

  1. Introduction to "Early psychosis

    DEFF Research Database (Denmark)

    McGorry, Patrick; Nordentoft, Merete; Simonsen, Erik

    2005-01-01

    warrants careful analysis. The Third International Early Psychosis Conference proved to be a watershed and was the largest and most vibrant meeting to that point. This preface aims to set the scene for a selection of contributions, derived from the array of new evidence reported in Copenhagen, and recently...

  2. Early Functional Abilities

    DEFF Research Database (Denmark)

    Lorentzen, Jakob; Poulsen, Ingrid

    2005-01-01

    Early Functional Abilities (EFA), - en skala til evaluering af behandlingsforløb af svært hjerneskadede patienter i forbindelse med tidlig rehabilitering. Formål At monitorere og dokumentere rehabiliteringsforløbet for svært hjerneskadede patienter, hvor funktionsniveauet endnu ikke kan registreres...

  3. Early Islamic Syria

    DEFF Research Database (Denmark)

    Walmsley, Alan George

    This book presents a new interpretation of social and economic developments in Syria-Palestine in the decades before and during the two centuries after the Islamic expansion into the region (roughly the later 6th to the early 9th century AD). Drawing on a wide range of evidence from recent...

  4. Teaching polymorphism early

    DEFF Research Database (Denmark)

    2005-01-01

    Is it possible to teach dynamic polymorphism early? What techniques could facilitate teaching it in Java. This panel will bring together people who have considered this question and attempted to implement it in various ways, some more completely than others. It will also give participants...

  5. Early childhood aggression

    NARCIS (Netherlands)

    Alink, Lenneke Rosalie Agnes

    2006-01-01

    In this thesis the development, stability, and correlates of early childhood aggression were investigated. The normative development was examined in a general population sample using questionnaires completed by the parents of 12-, 24-, and 36-month-old children and again one year later. Results

  6. Characteristics of early psychosis

    NARCIS (Netherlands)

    Schothorst, P.F.; Emck, C.; van Engeland, H.

    2006-01-01

    There is little research on characteristics related to course and prognosis of early-onset psychosis. The present article aims to advance our knowledge of this disorder for the purpose of proper diagnosis and treatment. It focuses on premorbid and prodromal characteristics, treatment history,

  7. Early practice: neurotology.

    Science.gov (United States)

    Breen, Joseph T; Vrabec, Jeffrey T

    2015-04-01

    Besides technical and surgical proficiency, some of the most important skills for a young Neurotologist to refine include communication and critical thinking abilities. This Early Practice article provides perspectives on common challenges and career development from a current Neurotology fellow and his mentor. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. Early Building Design

    DEFF Research Database (Denmark)

    Østergård, Torben; Jensen, Rasmus Lund; Maagaard, Steffen

    2017-01-01

    Highlights •Development of a design methodology that can handle the vast design space in early building design. •A global design space is modelled from extensive Monte Carlo simulations. •Sensitivity analysis methods applied to guide decision-makers. •Interactive visualizations help the multi-act...

  9. Early Childhood Trauma

    Science.gov (United States)

    National Child Traumatic Stress Network, 2010

    2010-01-01

    Early childhood trauma generally refers to the traumatic experiences that occur to children aged 0-6. Because infants' and young children's reactions may be different from older children's, and because they may not be able to verbalize their reactions to threatening or dangerous events, many people assume that young age protects children from the…

  10. Early prenatal syphilis

    Directory of Open Access Journals (Sweden)

    Santosh Rathod

    2010-01-01

    Full Text Available Syphilis in pregnancy still remains a challenge despite the availability of adequate diagnostic tests for serological screening and penicillin therapy. We report a case of 2 month old female infant who presented with runny nose, papulosquamous lesions over both palms and soles and perianal erosions since 1 month after birth. Cutaneous examination revealed moist eroded areas in the perianal region and fine scaly lesions over palms and soles. Radiograph of both upper limbs and limbs revealed early periosteal changes in lower end of humerus and lower end of tibia. Diagnosis of early pre-natal syphilis was confirmed by Child′s Serum Rapid Plasma Reagin Antibody test [S.RPR] being positive with 1:64 dilution while that of mother was 1:8.

  11. Early Childhood Caries

    Directory of Open Access Journals (Sweden)

    Yumiko Kawashita

    2011-01-01

    Full Text Available Dental caries is one of the most common childhood diseases, and people continue to be susceptible to it throughout their lives. Although dental caries can be arrested and potentially even reversed in its early stages, it is often not self-limiting and progresses without proper care until the tooth is destroyed. Early childhood caries (ECC is often complicated by inappropriate feeding practices and heavy infection with mutans streptococci. Such children should be targeted with a professional preventive program that includes oral hygiene instructions for mothers or caregivers, along with fluoride and diet counseling. However, these strategies alone are not sufficient to prevent dental caries in high-risk children; prevention of ECC also requires addressing the socioeconomic factors that face many families in which ECC is endemic. The aim of this paper is to systematically review information about ECC and to describe why many children are suffering from dental caries.

  12. Mapping the early Universe

    International Nuclear Information System (INIS)

    Anon.

    1991-01-01

    From its unique vantage point 900 kilometres above the earth's surface, NASA's Cosmic Background Explorer (COBE) satellite has a privileged view of cosmic background radiation - the remnants of the early (radiation-dominated) Universe which followed the Big Bang some ten Gigayears ago, and possibly some subsequent history. In this way astroparticle physicists get a first peek at the quantum cosmology which moulded the infant Universe

  13. Earthquake Early Warning Systems

    OpenAIRE

    Pei-Yang Lin

    2011-01-01

    Because of Taiwan’s unique geographical environment, earthquake disasters occur frequently in Taiwan. The Central Weather Bureau collated earthquake data from between 1901 and 2006 (Central Weather Bureau, 2007) and found that 97 earthquakes had occurred, of which, 52 resulted in casualties. The 921 Chichi Earthquake had the most profound impact. Because earthquakes have instant destructive power and current scientific technologies cannot provide precise early warnings in advance, earthquake ...

  14. Coaching in Early Mathematics.

    Science.gov (United States)

    Germeroth, Carrie; Sarama, Julie

    2017-01-01

    Falling scores in math have prompted a renewed interest in math instruction at early ages. By their own admission, early childhood educators are generally underprepared and not always comfortable teaching math. Professional development (PD) in early mathematics is widely considered a main way to increase teachers' skills and efficacy (e.g., Guskey, 2000; Hyson & Woods, 2014; Munby, Russell, & Martin, 2001; Piasta, Logan, Pelatti, Capps, & Petrill, 2015; Richardson & Placier, 2001; Sarama, Clements, Wolfe, & Spitler, 2016; Sarama & DiBiase, 2004; Zaslow, 2014). However, it has been documented that stand-alone PD is not as effective in changing practice (e.g., Biancarosa & Bryk, 2011; Garet et al., 2008; Guskey, 2000; Hyson & Woods, 2014; Institute of Medicine and National Research Council, 2015; Joyce & Showers, 2002; Zaslow, 2014). Site-embedded ongoing support in the form of coaching or mentoring has been shown to be critical for successful implementation (Neuman & Cunningham, 2009; Powell, Diamond, Burchinal, & Koehler, 2010). In this chapter, we describe coaching models and abstract characteristics of effective coaching from the research. With this background, we provide an in-depth view of the coaching aspect of two large empirical studies in early mathematics. We introduce the theoretical framework from which the coaching models for these projects were developed and describe the research on which they were based. We then summarize how the planned models were instantiated and challenges to their implementation within each project. In the final section, we summarize what we have learned and described implications and challenges for the field. © 2017 Elsevier Inc. All rights reserved.

  15. Early prevention of obesity

    OpenAIRE

    Claudio Maffeis

    2014-01-01

    Childhood obesity is the metabolic disorder with the highest prevalence in both children and adults. Urgency to treat and prevent childhood obesity is based on the clear evidence that obesity tends to track from childhood to adulthood, is associated to morbidity also in childhood and to long-term mortality. Early life, i.e., intrauterine life and the first two years, is a sensitive window for prevention. Anatomical and functional maturation of the hypothalamic structures devoted to regulating...

  16. Hands of early primates.

    Science.gov (United States)

    Boyer, Doug M; Yapuncich, Gabriel S; Chester, Stephen G B; Bloch, Jonathan I; Godinot, Marc

    2013-12-01

    Questions surrounding the origin and early evolution of primates continue to be the subject of debate. Though anatomy of the skull and inferred dietary shifts are often the focus, detailed studies of postcrania and inferred locomotor capabilities can also provide crucial data that advance understanding of transitions in early primate evolution. In particular, the hand skeleton includes characteristics thought to reflect foraging, locomotion, and posture. Here we review what is known about the early evolution of primate hands from a comparative perspective that incorporates data from the fossil record. Additionally, we provide new comparative data and documentation of skeletal morphology for Paleogene plesiadapiforms, notharctines, cercamoniines, adapines, and omomyiforms. Finally, we discuss implications of these data for understanding locomotor transitions during the origin and early evolutionary history of primates. Known plesiadapiform species cannot be differentiated from extant primates based on either intrinsic hand proportions or hand-to-body size proportions. Nonetheless, the presence of claws and a different metacarpophalangeal [corrected] joint form in plesiadapiforms indicate different grasping mechanics. Notharctines and cercamoniines have intrinsic hand proportions with extremely elongated proximal phalanges and digit rays relative to metacarpals, resembling tarsiers and galagos. But their hand-to-body size proportions are typical of many extant primates (unlike those of tarsiers, and possibly Teilhardina, which have extremely large hands). Non-adapine adapiforms and omomyids exhibit additional carpal features suggesting more limited dorsiflexion, greater ulnar deviation, and a more habitually divergent pollex than observed plesiadapiforms. Together, features differentiating adapiforms and omomyiforms from plesiadapiforms indicate increased reliance on vertical prehensile-clinging and grasp-leaping, possibly in combination with predatory behaviors in

  17. Early Detection Of Cancer

    Directory of Open Access Journals (Sweden)

    V B Bhatnagar

    1987-04-01

    Full Text Available Farly detection of cancer is based upon three fundamental assumptions, firstly that the trea'ment of benign and precancerous lesions reduces the incidence of cancer, secondly, that the treatment of in situ cancers is conducive to total cure and thirdly that early diagnosis and management of invasive cancer ensures be.ter survival. When patient seeks medical advice for vague symptoms, which could however be due to a possible malignant tumour at a particular site, the alert clinician should investigate the patient immediately to exclude cancer. At this stage cancer is usually not significantly advanced. Currently the U. I. C. C. (International Union for Cancer Control} is studying the epidemiology of cancers in various countries The importance of this is two folds : Firstly by focussing attention on a section of population vulnerable to a particular cancer an early detection is facilitated Secondly by changing the causative factors responsible to a particular cancer, the incidence of that cancer can be reduced e. g. reduction in lung cancer following campaigns against ciguette smoking and reductioi in breast cancer after campaigns for advocating breast feeding of infants, lowering fat consumption and encouraging self palpation of breast regularly. Indeed early diagnosis of cancer implies diagnosis of cancer in almost a symptomatic stage It involves motiva’ion of the population towards acquisitio : of knowledge, attitude and practice.. Epidemiologies and clinicians should be able to recognise high risk cases exposed to particular neoplasia and knowledge of alarming symptoms should be pro- pogated for wide publicity through common available media and means. Probable cases should have regular clhrcal examination periodically and relevant investigations including radiological, imaging techniques and Bio-Chemical examination should be undertaken as and when desired Suspicious lesions should be investigated by specific tests including smear cytology

  18. PHOBOS, the Early Years

    Science.gov (United States)

    Stephans, George S. F.; Back, B. B.; Baker, M. D.; Barton, D. S.; Betts, R. R.; Ballintijn, M.; Bickley, A. A.; Bindel, R.; Budzanowski, A.; Busza, W.; Carroll, A.; Decowski, M. P.; Garcia, E.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Heintzelman, G. A.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Holynski, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Katzy, J.; Khan, N.; Kucewicz, W.; Kulinich, P.; Kuo, C. M.; Lin, W. T.; Manly, S.; McLeod, D.; Michalowski, J.; Mignerey, A. C.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Remsberg, L. P.; Reuter, M.; Roland, C.; Roland, G.; Rosenberg, L.; Sagerer, J.; Sarin, P.; Sawicki, P.; Skulski, W.; Steadman, S. G.; Steinberg, P.; Stephans, G. S. F.; Stodulski, M.; Sukhanov, A.; Tang, J.-L.; Teng, R.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Verdier, R.; Wadsworth, B.; Wolfs, F. L. H.; Wosiek, B.; Wozniak, K.; Wuosmaa, A. H.; Wyslouch, B.

    2002-06-01

    The PHOBOS detector, one of the two small experiments at RHIC, focuses on measurements of charged particle multiplicity over almost the full phase space and identified particles near mid-rapidity. Results will be presented from the early RHIC gold--gold runs at nucleon--nucleon center of mass energies of 56 and 130 GeV as well as the recently concluded run at the full RHIC energy of 200 GeV.

  19. Mapping the early Universe

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1991-06-15

    From its unique vantage point 900 kilometres above the earth's surface, NASA's Cosmic Background Explorer (COBE) satellite has a privileged view of cosmic background radiation - the remnants of the early (radiation-dominated) Universe which followed the Big Bang some ten Gigayears ago, and possibly some subsequent history. In this way astroparticle physicists get a first peek at the quantum cosmology which moulded the infant Universe.

  20. Early breast cancer

    International Nuclear Information System (INIS)

    Dongen, J.A. van

    1989-01-01

    The therapy of early breast cancer has been changing during the last decennium. It requires a multi-disciplinary approach and in each of these disciplines improvements have been implemented. The result is that treatment schedules can now be adapted to specific subgroups. In this review early breast cancer is defined as operable disease, using the criteria set out by Haagensen. Emphasis is given to describing the new developments in prognostic criteria, since these form the basis for creating subgroups for specific treatment schedules. Distinction is made between the factors relating to growth rate and those relating to metastatic potential. Data on screening promises a beneficial effect of the implementation of screening in national health care programs. Important shifts are seen in treatment schedules; the place of postoperative radiotherapy after classic ablative treatment is being challenged, whereas it plays a major role in the new breast conserving therapy schedules. The data mentioned in the review suggest that a large proportion of 'operable' cases can be treated with breast conservation but details in the technique of breast conserving therapy are still under investigation. They form a major part of the coming prospective studies in breast cancer. Improvements in reconstruction techniques, creating better cosmetic results, make reconstruction more competitive with breast conserving therapy. The use of chemotherapy and endocrine manipulation in early breast cancer has now been clearly confirmed by the overview technique by the Peto-group, thanks to all efforts of individual trialists together. (orig.)

  1. Early intervention as a catalyst for effective early childhood ...

    African Journals Online (AJOL)

    ... of positive attitudes towards children with disabilities in a country like Ghana. ... As Ghana strides towards mainstreaming early childhood education in the quest ... an integrated, inclusive and effective early intervention programme becomes ...

  2. Infusing Early Childhood Mental Health into Early Intervention Services

    Science.gov (United States)

    Grabert, John C.

    2009-01-01

    This article describes the process of enhancing early childhood mental health awareness and skills in non-mental health staff. The author describes a pilot training model, conducted the U.S. Army's Early Intervention Services, that involved: (a) increasing early childhood mental health knowledge through reflective readings, (b) enhancing…

  3. Early Life Exposures and Cancer

    Science.gov (United States)

    Early-life events and exposures have important consequences for cancer development later in life, however, epidemiological studies of early-life factors and cancer development later in life have had significant methodological challenges.

  4. History of early atomic clocks

    International Nuclear Information System (INIS)

    Ramsey, N.F.

    2005-01-01

    This review of the history of early atomic clocks includes early atomic beam magnetic resonance, methods of separated and successive oscillatory fields, microwave absorption, optical pumping and atomic masers. (author)

  5. Early prevention of obesity

    Directory of Open Access Journals (Sweden)

    Claudio Maffeis

    2014-06-01

    Full Text Available Childhood obesity is the metabolic disorder with the highest prevalence in both children and adults. Urgency to treat and prevent childhood obesity is based on the clear evidence that obesity tends to track from childhood to adulthood, is associated to morbidity also in childhood and to long-term mortality. Early life, i.e., intrauterine life and the first two years, is a sensitive window for prevention. Anatomical and functional maturation of the hypothalamic structures devoted to regulating energy intake and expenditure and body size mainly occurs in the first 1,000 days of life. Therefore, factors affecting the foetal exposition to maternal metabolic environment and early postnatal nutrition are crucial in modulating the definition of the metabolic programming processes in the brain. Maternal diseases, mainly malnutrition for defect or excess, obesity and diabetes, placental disorders and dysfunctions, maternal use of alcohol and drugs, smoking, affect long term metabolic programming of the foetus with lifelong consequences. Similarly, early nutrition contributes to complete the long-term metabolic regulating framework initiated in the uterus. Breastfeeding, adequate weaning, attention to portion size and diet composition are potential tools for reducing the obesity risk later in childhood. Longitudinal randomized controlled studies are needed for exploring the efficacy of obesity prevention strategies initiated after conception.Proceedings of the 10th International Workshop on Neonatology · Cagliari (Italy · October 22nd-25th, 2014 · The last ten years, the next ten years in Neonatology Guest Editors: Vassilios Fanos, Michele Mussap, Gavino Faa, Apostolos Papageorgiou

  6. Crowdsourced earthquake early warning

    Science.gov (United States)

    Minson, Sarah E.; Brooks, Benjamin A.; Glennie, Craig L.; Murray, Jessica R.; Langbein, John O.; Owen, Susan E.; Heaton, Thomas H.; Iannucci, Robert A.; Hauser, Darren L.

    2015-01-01

    Earthquake early warning (EEW) can reduce harm to people and infrastructure from earthquakes and tsunamis, but it has not been implemented in most high earthquake-risk regions because of prohibitive cost. Common consumer devices such as smartphones contain low-cost versions of the sensors used in EEW. Although less accurate than scientific-grade instruments, these sensors are globally ubiquitous. Through controlled tests of consumer devices, simulation of an Mw (moment magnitude) 7 earthquake on California’s Hayward fault, and real data from the Mw 9 Tohoku-oki earthquake, we demonstrate that EEW could be achieved via crowdsourcing.

  7. Why Recruits Separate Early

    Science.gov (United States)

    1991-01-01

    our sample were reportedly unable to adjust to the military environment due to social or emotional immaturity. This problem was especially prevalent...Table 9. Table 9 REASONS FOR EARLY SEPARATION 1. Mental health. Phobias , suicide threats and attempts, emotional immaturity, and personality and...hliurfl’lutf t’ htrtiuug tht .’ plinittol piioL’m.9 evIn’ thfll I b’ r i’lli. vre’.Ilv ifao~ , ýI ll.tv ill it](- rv ’: 111nil tln1 (i~..󈧏 4 P A W4.11

  8. Early modern mathematical instruments.

    Science.gov (United States)

    Bennett, Jim

    2011-12-01

    In considering the appropriate use of the terms "science" and "scientific instrument," tracing the history of "mathematical instruments" in the early modern period is offered as an illuminating alternative to the historian's natural instinct to follow the guiding lights of originality and innovation, even if the trail transgresses contemporary boundaries. The mathematical instrument was a well-defined category, shared across the academic, artisanal, and commercial aspects of instrumentation, and its narrative from the sixteenth to the eighteenth century was largely independent from other classes of device, in a period when a "scientific" instrument was unheard of.

  9. Early solar physics

    CERN Document Server

    Meadows, A J

    1970-01-01

    Early Solar Physics reviews developments in solar physics, particularly the advent of solar spectroscopy and the discovery of relationships between the various layers of the solar atmosphere and between the different forms of solar activity. Topics covered include solar observations during 1843; chemical analysis of the solar atmosphere; the spectrum of a solar prominence; and the solar eclipse of December 12, 1871. Spectroscopic observations of the sun are also presented. This book is comprised of 30 chapters and begins with an overview of ideas about the sun in the mid-nineteenth century, fo

  10. Early and late motherhood

    DEFF Research Database (Denmark)

    Christoffersen, Mogens; Lausten, Mette

    2009-01-01

    The study investigates parental child rearing methods, structural factors relating to the family during adolescence geographic segregation, individual resource deficits and social background of first time late live births among 32 to 37 years old women and compare to teenagers before becoming...... economic and social gradient for first-time teenage mothers. Teenagers who had experienced family separation or who were formerly in out-of-home care in particular had an increased risk of early childbearing. Results showed that teenage mothers were in every respect in a more disadvantaged position than...

  11. Early Reading and Concrete Operations.

    Science.gov (United States)

    Polk, Cindy L. Howes; Goldstein, David

    1980-01-01

    Indicated that early readers are more likely to be advanced in cognitive development than are nonearly-reading peers. After one year of formal reading instruction, early readers maintained their advantage in reading achievement. Measures of concrete operations were found to predict reading achievement for early and nonearly readers. (Author/DB)

  12. Early Childhood Workforce Index, 2016

    Science.gov (United States)

    Whitebook, Marcy; McLean, Caitlin; Austin, Lea J. E.

    2016-01-01

    The State of the Early Childhood Workforce (SECW) Initiative is a groundbreaking multi-year project to shine a steady spotlight on the nation's early childhood workforce. The SECW Initiative is designed to challenge entrenched ideas and policies that maintain an inequitable and inadequate status quo for early educators and for the children and…

  13. Radiation early warning system

    International Nuclear Information System (INIS)

    Schmitzer, C.; Kloesch, W.; Stadtmann, H.

    1993-01-01

    A prototype station for a Radiation Early Warning Network has been designed and set up at the Austrian Research Centre Seibersdorf. This unit was developed to measure all relevant parameters necessary to detect and track radioactive contamination at an early stage. The station consists of the following components: Radiation measuring channel for ambient gamma dose rate. Meteorological measurement channels for air temperature and humidity, wind direction and wind speed, and precipitation. Data processing and storage unit. The system is capable of unattended operation and data acquisition even under adverse environmental conditions. Connection to a central processing platform may be achieved via leased line, dial up over public switched telephone network (PSTN), or radio-frequency transmission. The remote station will continue acquiring and storing data for at least a month, even if the communications link is broken. Multiple stations can be combined to form a network, providing detailed information about radiological and meteorological data at each site. Thus increased ambient radiation levels may be discovered, tracked, and forecasted based on calculations using current and local weather data

  14. Sonority and early words

    DEFF Research Database (Denmark)

    Kjærbæk, Laila; Boeg Thomsen, Ditte; Lambertsen, Claus

    2015-01-01

    Syllables play an important role in children’s early language acquisition, and children appear to rely on clear syllabic structures as a key to word acquisition (Vihman 1996; Oller 2000). However, not all languages present children with equally clear cues to syllabic structure, and since the spec......Syllables play an important role in children’s early language acquisition, and children appear to rely on clear syllabic structures as a key to word acquisition (Vihman 1996; Oller 2000). However, not all languages present children with equally clear cues to syllabic structure, and since...... acquisition therefore presents us with the opportunity to examine how children respond to the task of word learning when the input language offers less clear cues to syllabic structure than usually seen. To investigate the sound structure in Danish children’s lexical development, we need a model of syllable......-29 months. For the two children, the phonetic structure of the first ten words to occur is compared with that of the last ten words to occur before 30 months of age, and with that of ten words in between. Measures related to the sonority envelope, viz. sonority types and in particular sonority rises...

  15. Early-Onset Dementia

    DEFF Research Database (Denmark)

    Konijnenberg, Elles; Fereshtehnejad, Seyed-Mohammad; Kate, Mara Ten

    2017-01-01

    BACKGROUND: Early-onset dementia (EOD) is a rare condition, with an often atypical clinical presentation, and it may therefore be challenging to diagnose. Specialized memory clinics vary in the type of patients seen, diagnostic procedures applied, and the pharmacological treatment given. The aim...... of this study was to investigate quality-of-care indicators in subjects with EOD from 3 tertiary memory clinics in 3 European countries. METHODS: We included 1325 newly diagnosed EOD patients, ages 65 years or younger, between January 1, 2007 and December 31, 2013, from the Danish Dementia Registry...... (Rigshospitalet, Copenhagen), the Swedish Dementia Registry ("SveDem", Karolinska University Hospital, Stockholm), and the Amsterdam Dementia Cohort (VU University Medical Center). RESULTS: The frequency of EOD among all dementia patients was significantly lower in Copenhagen (410, 20%) and Stockholm (284, 21...

  16. Manipulating early pig embryos.

    Science.gov (United States)

    Niemann, H; Reichelt, B

    1993-01-01

    On the basis of established surgical procedures for embryo recovery and transfer, the early pig embryo can be subjected to various manipulations aimed at a long-term preservation of genetic material, the generation of identical multiplets, the early determination of sex or the alteration of the genetic make-up. Most of these procedures are still at an experimental stage and despite recent considerable progress are far from practical application. Normal piglets have been obtained after cryopreservation of pig blastocysts hatched in vitro, whereas all attempts to freeze embryos with intact zona pellucida have been unsuccessful. Pig embryos at the morula and blastocyst stage can be bisected microsurgically and the resulting demi-embryos possess a high developmental potential in vitro, whereas their development in vivo is impaired. Pregnancy rates are similar (80%) but litter size is reduced compared with intact embryos and twinning rate is approximately 2%. Pig blastomeres isolated from embryos up to the 16-cell stage can be grown in culture and result in normal blastocysts. Normal piglets have been born upon transfer of blastocysts derived from isolated eight-cell blastomeres, clearly underlining the totipotency of this developmental stage. Upon nuclear transfer the developmental capacity of reconstituted pig embryos is low and culture. Sex determination can be achieved either by separation of X and Y chromosome bearing spermatozoa by flow cytometry or by analysing the expression of the HY antigen in pig embryos from the eight-cell to morula stage. Microinjection of foreign DNA has been successfully used to alter growth and development of transgenic pigs, and to produce foreign proteins in the mammary gland or in the bloodstream, indicating that pigs can be used as donors for valuable human pharmaceutical proteins. Another promising area of gene transfer is the increase of disease resistance in transgenic lines of pigs. Approximately 30% of pig spermatozoa bind

  17. Subduction on Venus and Implications for Volatile Cycling, Early Earth and Exoplanets

    Science.gov (United States)

    Smrekar, S. E.; Davaille, A.; Mueller, N. T.; Dyar, M. D.; Helbert, J.; Barnes, H.

    2017-12-01

    it a good analog of Earth's Archean. There is increasing evidence that Venus is a dynamic planet with possible active and/or recent volcanism and subduction. Studying these processes on Venus provides a window into both early Earth and offers constraints on the conditions needed to initiate plate tectonics on exoplanets.

  18. EARLY ENTRANCE COPRODUCTION PLANT

    Energy Technology Data Exchange (ETDEWEB)

    John S. Abughazaleh; Mushtaq Ahmed; Ashok Anand; John H. Anderson; Charles Benham; Fred D. Brent; Thomas E. Chance; William K. Davis; Raymond F. Drnevich; Larry Hall; Ming He; Stephen A. Lang; David Mintner; Wendy Moore; Jimmy O. Ong; George Potoczniak; Adela G. Sanchez; Charles H. Schrader; Lalit S. Shah; Kalapi D. Sheth; Phil J. Shires; Rae Song

    2001-05-17

    The overall objective of this project is the three-phase development of an Early Entrance Coproduction Plant (EECP) that produces at least one product from at least two of the following three categories: Electric power (or heat); Fuels; and Chemicals. The objective is to have these products produced by technologies capable of using synthesis gas derived from coal and/or some other carbonaceous feedstock, such as petroleum coke. The objective of Phase I was to determine the feasibility and define the concept for the EECP located at a specific site and to develop a Research, Development, and Testing (RD and T) Plan for implementation in Phase II. This objective has now been accomplished. A specific site, Motiva Refinery in Port Arthur, Texas, has been selected as the location best suited for the EECP. The accomplishments of Phase I are discussed in detail in this Phase I Concept Report. A RD and T Plan and a preliminary project financing plan have been developed and are submitted separately from this report.

  19. The Early Experiments

    Science.gov (United States)

    Garvey, Gerald

    2013-04-01

    Stuart Freedman obtained his PhD at Berkley with an experimental thesis providing very strong evidence against theories requiring local hidden variables. He then came to Princeton in 1972 and began collaboration on a search for second-class currents. These measurements are quite difficult as the effects are the order of 1%, demonstrating Freedman's drive to take on hard but important experiments. After carrying out some relatively standard nuclear physics measurements he moved on to Stanford in 1976. There, Freedman was involved in identifying measurements sensitive to the existence of light axions. He also carried out searches for various exotica that might be produced from cosmic rays or the SLAC beam stop. During this time he was collaborating with us at Argonne investigating nuclear parity violation and time-like axial beta decay. In 1982 Freedman came to Argonne where he worked on fundamental issues in neutron beta decay. He also initiated what was to become one of his trademarks, demonstrating that surprising peaks in the e^+-e^- spectrum observed in very heavy ion collisions were spurious. He further launched his first neutrino oscillation experiment. This period of early research was marked by a remarkable diversity of subject matter and approach.

  20. Early diagnosis of leptospirosis

    Directory of Open Access Journals (Sweden)

    Andrea Babic-Erceg

    2014-06-01

    Full Text Available A 25-years old man from Zagreb, Croatia, was admitted to the University Hospital for Infectious Diseases four days after the onset of symptoms such as fever, intense pain in the calves and anuria. The patient owned a rabbit and, before the onset of the disease, repaired some rubber pipes damaged by rodents. At admission, he had a severe clinical picture with fever, hypotension, jaundice, immobility, and pain in leg muscles. Treatment with ceftriaxone was initiated in combination with volume restitution. Renal failure soon ensued. Consequently continuous venovenous hemodiaphiltration therapy was performed. Due to acute respiratory distress syndrome, the patient was mechanically ventilated. The patient’s condition gradually improved and he recovered fully from multi-organ failure. Diagnosis was confirmed by a microscopic agglutination test (MAT covering 15 leptospira serovars and real-time polymerase-chain reaction (PCR. The first serum sample taken on day 6 tested negative for leptospira, while PCR showed positive results for leptospiral DNA. The second serum sample taken on day 13 tested positive for serovar Canicola serogroup Canicola, serovar Patoc, serovar Grippotyphosa serogroup Grippotyphosa and serovar Tarassovi serogroup Tarassovi (titre 4000, 4000, 1000 and 2000, respectively, while PCR was negative. This report highlights the benefits of combining MAT and PCR methods in early diagnosis of leptospirosis.

  1. EARLY ENTRANCE COPRODUCTION PLANT

    International Nuclear Information System (INIS)

    William K. Davis

    2001-01-01

    The overall objective of this project is the three phase development of an Early Entrance Coproduction Plant (EECP) which produces at least one product from at least two of the following three categories: (1) electric power (or heat), (2) fuels, and (3) chemicals. The objective is to have these products produced by technologies capable of using synthesis gas derived from coal and/or other carbonaceous feedstocks. The objective of Phase I is to determine the feasibility and define the concept for the EECP located at a specific site; develop a Research, Development, and Testing (RD and T) Plan for implementation in Phase II; and prepare a Preliminary Project Financing Plan. The objective of Phase II is to implement the work as outlined in the Phase I RD and T Plan to enhance the development and commercial acceptance of coproduction technology that produces high-value products, particularly those that are critical to our domestic fuel and power requirements. The project will resolve critical knowledge and technology gaps on the integration of gasification and downstream processing to coproduce some combination of power, fuels, and chemicals from coal and/or other carbonaceous feedstocks. The objective of Phase III is to develop an engineering design package and a financing plan for an EECP located at a specific site. The project's intended result is to provide the necessary technical, economic, and environmental information needed by industry to move the EECP forward to detailed design, construction, and operation

  2. Archean crustal evolution in the central Minto block, northern Quebec

    International Nuclear Information System (INIS)

    Skulski, T.; Percival, J.A.; Stern, R.A.

    1996-01-01

    The central Minto block contains three volcano-sedimentary successions. Near Lake Qalluviartuuq, an isotopically primitive ( 2.83 Ga ε Nd +3.8 to +2.3) 2.83 Ga volcano-plutonic sequence comprises depleted tholeiitic basalts, anorthositic gabbro, and diorite-granodiorite that is unconformably overlain by 2.76 Ga ε Nd +1.8) calc-alkaline sequence of pillow basalts, andesites, and peridotite cut by 2.73 Ga diorite. To the west, and in inferred tectonic contact, the sediment-dominated Kogaluc sequence includes both isotopically evolved calc-alkaline rocks ( 2.76 Ga ε Nd +1.6 to -0.1) including 2.78Ga ε Nd Nd 2.725Ga ε Nd - 1. 6). (author). 19 refs., 4 tabs., 5 figs

  3. Archean crustal evolution in the central Minto block, northern Quebec

    Energy Technology Data Exchange (ETDEWEB)

    Skulski, T; Percival, J A; Stern, R A [Geological Survey of Canada, Ottawa, ON (Canada)

    1997-12-31

    The central Minto block contains three volcano-sedimentary successions. Near Lake Qalluviartuuq, an isotopically primitive ({sup 2.83} {sup Ga}{epsilon}{sub Nd} +3.8 to +2.3) 2.83 Ga volcano-plutonic sequence comprises depleted tholeiitic basalts, anorthositic gabbro, and diorite-granodiorite that is unconformably overlain by <2.77 Ga conglomerates. Overlying the conglomerate is a more evolved ({sup 2.76} {sup Ga}{epsilon}{sub Nd} +1.8) calc-alkaline sequence of pillow basalts, andesites, and peridotite cut by 2.73 Ga diorite. To the west, and in inferred tectonic contact, the sediment-dominated Kogaluc sequence includes both isotopically evolved calc-alkaline rocks ({sup 2.76} {sup Ga}{epsilon}{sub Nd} +1.6 to -0.1) including <2.76 Ga rhyolitic tuff, pillowed andesites, and 2.76 Ga quartz-feldspar porphyry, and less abundant, depleted tholeiitic basalts (2.76 GaF-Nd +2.4). These are interlain with sedimentary rocks including banded iron-formation, quartzite, and metagreywacke. Calc-alkaline batholiths include 2.78 Ga pyroxene-bearing intermediate and felsic plutons ({sup 2.78Ga}{epsilon}{sub Nd} <+2.7) and younger, peraluminous tonalites ({epsilon}{sub Nd} <+1.3). Late, 2.73 Ga peraluminous granitoids are isotopically evolved ({sup 2.725Ga}{epsilon}{sub Nd} - 1. 6). (author). 19 refs., 4 tabs., 5 figs.

  4. Geochemistry of some banded iron-formations of the archean ...

    Indian Academy of Sciences (India)

    Diagenetic fluids from the sea floor sediments and river water might have played .... (in wt%) of the banded iron-formations of Archaean supracrustal belts (Iron Ore Group) of Jharkhand–Orissa region. Gandhamardan. Deo river section. H/1/1 H/1/2 H/1/3 H/1/4 H/1/5 .... indicate that contamination by pyroclastic debris.

  5. carbonaceous phyllite/graphitic schist in the Archean Kundarkocha

    Indian Academy of Sciences (India)

    rocks of noble metals (Meyers et al. 1990). Such complexes host gold deposits in North–East. Russia (Natalka, Mayskoe ..... carbonic phases using Laser Raman Spectrometry ... Graphite was formed by the reaction between CH4 and CO2.

  6. REE Geochemistry of ore zones in the Archean auriferous schist ...

    Indian Academy of Sciences (India)

    R. Narasimhan, Krishtel eMaging Solutions

    the fluids could be of higher temperature origin. The initial Nd ... of mantle CO2 along shear zones in the lower crust led to the ..... tors such as permeability and composition of pro- ...... Shenberger D M and Barnes H L 1989 Solubility of gold in ...

  7. Is credit for early action credible early action?

    International Nuclear Information System (INIS)

    Rolfe, C.; Michaelowa, A.; Dutschke, M.

    1999-12-01

    Credit for early action as a tool for greenhouse gas emissions reduction is compared with various market instruments as a means of narrowing the gap between projected emissions and those of the Kyoto Protocol. Market instruments work by creating a market price for emissions and use the market to encourage reductions at the lowest price, which is done by placing limits on greenhouse gas emissions and allowing the market to decide where reductions occur, or by imposing a carbon tax or emissions charge. While they can be applied within a sector, they are usually used to encourage reductions throughout the economy or across large sectors. Credit for early action also creates an incentive for emissions reductions throughout the economy or at least across many sectors. Credit for early action tools do not work by either imposing a carbon tax or emissions charge or placing limits on emissions, rather they promise that entities that take action against greenhouse gases prior to the imposition of a carbon tax or emissions limits will receive a credit against future taxes or limits. An overview is provided of the Kyoto Protocol and the rationale for taking early action, and a review is included of the theory and specific proposals for market instruments and credit for early action. A comparative analysis is provided of these approaches by examining their relative efficiency, environmental effectiveness, and impacts on the redistribution of wealth. Credit for early action is viewed as problematic on a number of counts and is seen as an interim strategy for imposition while political support for market instruments develop. The environmental effectiveness of credit for early action is very difficult to predict, and credit for early action programs do not yield the lowest cost emissions reductions. Credit for early action programs will not achieve compliance with the Kyoto Protocol at the lowest cost, and credits for early action will increase the compliance costs for those who

  8. Earth's earliest biosphere: Its origin and evolution

    International Nuclear Information System (INIS)

    Schopf, J.W.

    1983-01-01

    Some of the subjects discussed are related to the early biogeologic history, the nature of the earth prior to the oldest known rock record, the early earth and the Archean rock record, the prebiotic organic syntheses and the origin of life, Precambrian organic geochemistry, the biochemical evolution of anaerobic energy conversion, the isotopic inferences of ancient biochemistries, Archean stromatolites providing evidence of the earth's earliest benthos, Archean microfossils, the geologic evolution of the Archean-Early Proterozoic earth, and the environmental evolution of the Archean-Early Proterozoic earth. Other topics examined are concerned with geochemical evidence bearing on the origin of aerobiosis, biological and biochemical effects of the development of an aerobic environment, Early Proterozoic microfossils, the evolution of earth's earliest ecosystems, and geographic and geologic data for processed rock samples. Attention is given to a processing procedure for abiotic samples and calculation of model atmospheric compositions, and procedures of organic geochemical analysis

  9. Early tetrapod relationships revisited.

    Science.gov (United States)

    Ruta, Marcello; Coates, Michael I; Quicke, Donald L J

    2003-05-01

    In an attempt to investigate differences between the most widely discussed hypotheses of early tetrapod relationships, we assembled a new data matrix including 90 taxa coded for 319 cranial and postcranial characters. We have incorporated, where possible, original observations of numerous taxa spread throughout the major tetrapod clades. A stem-based (total-group) definition of Tetrapoda is preferred over apomorphy- and node-based (crown-group) definitions. This definition is operational, since it is based on a formal character analysis. A PAUP* search using a recently implemented version of the parsimony ratchet method yields 64 shortest trees. Differences between these trees concern: (1) the internal relationships of aïstopods, the three selected species of which form a trichotomy; (2) the internal relationships of embolomeres, with Archeria crassidisca and Pholiderpeton scut collapsed in a trichotomy with a clade formed by Anthracosaurus russelli and Pholiderpeton attheyi; (3) the internal relationships of derived dissorophoids, with four amphibamid species forming an unresolved node with a clade consisting of micromelerpetontids and branchiosaurids and a clade consisting of albanerpetontids plus basal crown-group lissamphibians; (4) the position of albenerpetontids and Eocaecilia micropoda, which form an unresolved node with a trichotomy subtending Karaurus sharovi, Valdotriton gracilis and Triadobatrachus massinoti; (5) the branching pattern of derived diplocaulid nectrideans, with Batrachiderpeton reticulatum and Diceratosaurus brevirostris collapsed in a trichotomy with a clade formed by Diplocaulus magnicornis and Diploceraspis burkei. The results of the original parsimony run--as well as those retrieved from several other treatments of the data set (e.g. exclusion of postcranial and lower jaw data; character reweighting; reverse weighting)--indicate a deep split of early tetrapods between lissamphibian- and amniote-related taxa. Colosteids, Crassigyrinus

  10. Early onset sebaceous carcinoma

    Directory of Open Access Journals (Sweden)

    Kaltreider Sara A

    2011-09-01

    Full Text Available Abstract Background Ocular sebaceous carcinoma can masquerade as benign lesions resulting in delay of diagnosis. Early recognition is even more difficult in young patients where the disease rarely occurs. Here, we provide a clinicopathological correlation of ocular sebaceous carcinoma in a young individual lacking history of hereditary cancer or immunosuppression. Findings A detailed histopathological study including p53 DNA sequencing was performed on an aggressive sebaceous carcinoma presenting in a healthy 32 year-old Caucasian woman. She had no history of retinoblastoma, evidence for a hereditary cancer syndrome, or radiation therapy. However, she potentially was at risk for excessive UV light exposure. A detailed review of the literature is also provided. A moderately well differentiated sebaceous carcinoma was established histopathologically arising from the meibomian gland of the upper eyelid. In most areas, the cytoplasm contained small but distinct Oil-red-O positive vacuoles. Direct sequencing of p53 identified a G:C→A:T mutation at a dipyrimidine site. The mutation results in substitution of arginine for the highly conserved glycine at residue 199 located at the p53 dimer-dimer interface. Energy minimization structural modeling predicts that G199R will neutralize negative charges contributed by nearby inter- and intramonomeric glutamate residues. Discussion This study points to the importance of recognizing that sebaceous carcinoma can occur in young patients with no evidence for hereditary cancer risk or radiation therapy. The G199R substitution is anticipated to alter the stability of the p53 tetrameric complex. The role of UV light in the etiology of sebaceous carcinoma deserves further study. Our findings, taken together with those of others, suggest that different environmental factors could lead to the development of sebaceous carcinoma in different patients.

  11. Late Jurassic-Early Cretaceous episodic development of the Bangong Meso-Tethyan subduction: Evidence from elemental and Sr-Nd isotopic geochemistry of arc magmatic rocks, Gaize region, central Tibet, China

    Science.gov (United States)

    Zhang, Yu-Xiu; Li, Zhi-Wu; Yang, Wen-Guang; Zhu, Li-Dong; Jin, Xin; Zhou, Xiao-Yao; Tao, Gang; Zhang, Kai-Jun

    2017-03-01

    The Bangong Meso-Tethys plays a critical role in the development of the Tethyan realm and the initial elevation of the Tibetan Plateau. However, its precise subduction polarity, and history still remain unclear. In this study, we synthesize a report for the Late Jurassic-Early Cretaceous two-phase magmatic rocks in the Gaize region at the southern margin of the Qiangtang block located in central Tibet. These rocks formed during the Late Jurassic-earliest Cretaceous (161-142 Ma) and Early Cretaceous (128-106 Ma), peaking at 146 Ma and 118 Ma, respectively. The presence of inherited zircons indicates that an Archean component exists in sediments in the shallow Qiangtang crust, and has a complex tectonomagmatic history. Geochemical and Sr-Nd isotopic data show that the two-phase magmatic rocks exhibit characteristics of arc magmatism, which are rich in large-ion incompatible elements (LIIEs), but are strongly depleted in high field strength elements (HFSEs). The Late Jurassic-earliest Cretaceous magmatic rocks mixed and mingled among mantle-derived mafic magmas, subduction-related sediments, or crustally-derived felsic melts and fluids, formed by a northward and steep subduction of the Bangong Meso-Tethys ocean crust. The magmatic gap at 142-128 Ma marks a flat subduction of the Meso-Tethys. The Early Cretaceous magmatism experienced a magma MASH (melting, assimilation, storage, and homogenization) process among mantle-derived mafic magmas, or crustally-derived felsic melts and fluids, as a result of the Meso-Tethys oceanic slab roll-back, which triggered simultaneous back-arc rifting along the southern Qiangtang block margin.

  12. Early determinants of mental health

    NARCIS (Netherlands)

    Räikkönen, Katri; Pesonen, Anu-Katriina; Roseboom, Tessa J.; Eriksson, Johan G.

    2012-01-01

    Environmental adversities in pre- and early postnatal life may have life-long consequences. Based upon a series of epidemiological and clinical studies and natural experiments, this review describes how the early life environment may affect psychological functions and mental disorders later in life.

  13. Early Childhood Education in Taiwan.

    Science.gov (United States)

    Barclay, Lisa K.

    1989-01-01

    Describes early childhood education in Taiwan, focusing on living patterns and child care arrangements, the position of the individual within the family and community, and the application of cultural norms to early childhood education. Compares the behavior of Chinese preschool children to that of American preschool children. (RJC)

  14. Cell Analysis and Early Diagnostics

    NARCIS (Netherlands)

    Subramaniam, Vinod; Jones, Val

    2006-01-01

    In an era of aging populations and rising health-care costs, the shift of medical paradigms towards rapid, accurate, early diagnoses of diseases is inevitable. In addition to further development of ultrasensitive in vitro tests, the focus of attention in both diagnostics and the early drug discovery

  15. Early Childhood Inclusion in Spain

    Science.gov (United States)

    Giné, Climent; Balcells-Balcells, Anna; Cañadas, Margarita; Paniagua, Gema

    2016-01-01

    This article describes early childhood inclusion in educational settings in Spain. First, we address the legislative framework of preschool education in Spain and offer a brief analysis of some relevant issues, including the current situation of early childhood education and inclusion at this stage. Second, current policies and practices relating…

  16. Excess hafnium-176 in meteorites and the early Earth zircon record

    DEFF Research Database (Denmark)

    Bizzarro, Martin; Connelly, James; Thrane, Kristine

    2012-01-01

    The long-lived Lu-to- Hf decay system is a powerful tool to understand ancient chemical fractionation events associated with planetary differentiation. Detrital Hadean zircons (>3.8 Gyr) from the Jack Hills metasedimentary belt of Western Australia record extremely enriched Hf-isotope signals sug...... crust prior to ~4.4 Gyr. This new view suggests continuous juvenile crustal growth and recycling throughout the Hadean and Archean eras, perhaps analogous to modern plate tectonics....

  17. Early diagnosis and early intervention in cerebral palsy

    Directory of Open Access Journals (Sweden)

    Mijna eHadders-Algra

    2014-09-01

    Full Text Available This paper reviews the opportunities and challenges for early diagnosis and early intervention in cerebral palsy (CP. CP describes a group of disorders of the development of movement and posture, causing activity limitation, that are attributed to disturbances that occurred in the fetal or infant brain. Therefore the paper starts with a summary of relevant information from developmental neuroscience. Most lesions underlying CP occur in the second half of gestation, when developmental activity in the brain reaches its summit. Variations in timing of the damage not only result in different lesions, but also in different neuroplastic reactions and different associated neuropathologies. This turns CP into a heterogeneous entity. This may mean that the best early diagnostics and the best intervention methods may differ for various subgroups of children with CP. Next, the paper addresses possibilities for early diagnosis. It discusses the predictive value of neuromotor and neurological exams, neuro-imaging techniques and neurophysiological assessments. Prediction is best when complementary techniques are used in longitudinal series. Possibilities for early prediction of CP differ for infants admitted to neonatal intensive care and other infants. In the former group best prediction is achieved with the combination of neuro-imaging and the assessment of general movements, in the latter group best prediction is based on carefully documented milestones and neurological assessment. The last part reviews early intervention in infants developing CP. Most knowledge on early intervention is based on studies in high risk infants without CP. In these infants early intervention programs promote cognitive development until preschool age; motor development profits less. The few studies on early intervention in infants developing CP suggest that programs that stimulate all aspects of infant development by means of family coaching are most promising. More research is

  18. Massive Hydrothermal Flows of Fluids and Heat: Earth Constraints and Ocean World Considerations

    Science.gov (United States)

    Fisher, A. T.

    2018-05-01

    This presentation reviews the hydrogeologic nature of Earth's ocean crust and evidence for massive flows of low-temperature (≤70°C), seafloor hydrothermal circulation through ridge flanks, including the influence of crustal relief and crustal faults.

  19. Early Maternal Time Investment and Early Child Outcomes

    OpenAIRE

    Del Bono, Emilia; Francesconi, Marco; Kelly, Yvonne; Sacker, Amanda

    2014-01-01

    Using large longitudinal survey data from the UK Millennium Cohort Study, this paper estimates the relationship between maternal time inputs and early child development. We find that maternal time is a quantitatively important determinant of skill formation and that its effect declines with child age. There is evidence of long-term effects of early maternal time inputs on later outcomes, especially in the case of cognitive skill development. In the case of non-cognitive development, the evide...

  20. EARLY ENTRANCE COPRODUCTION PLANT

    Energy Technology Data Exchange (ETDEWEB)

    Fred D. Brent; Lalit Shah; Earl Berry; Charles H. Schrader; John Anderson; Ming He; James F. Stevens; Centha A. Davis; Michael Henley; Jerome Mayer; Harry Tsang; Jimell Erwin; Jennifer Adams; Michael Tillman; Chris Taylor; Marjan J. Roos; Robert F. Earhart

    2004-01-27

    The overall objective of this project is the three phase development of an Early Entrance Coproduction Plant (EECP) which uses petroleum coke to produce at least one product from at least two of the following three categories: (1) electric power (or heat), (2) fuels, and (3) chemicals using ChevronTexaco's proprietary gasification technology. The objective of Phase I is to determine the feasibility and define the concept for the EECP located at a specific site; develop a Research, Development, and Testing (RD&T) Plan to mitigate technical risks and barriers; and prepare a Preliminary Project Financing Plan. The objective of Phase II is to implement the work as outlined in the Phase I RD&T Plan to enhance the development and commercial acceptance of coproduction technology. The objective of Phase III is to develop an engineering design package and a financing and testing plan for an EECP located at a specific site. The project's intended result is to provide the necessary technical, economic, and environmental information needed by industry to move the EECP forward to detailed design, construction, and operation. The partners in this project are Texaco Energy Systems LLC or TES (a subsidiary of ChevronTexaco), General Electric (GE), Praxair, and Kellogg Brown & Root (KBR) in addition to the U.S. Department of Energy (DOE). TES is providing gasification technology and Fischer-Tropsch (F-T) technology developed by Rentech, GE is providing combustion turbine technology, Praxair is providing air separation technology, and KBR is providing engineering. Each of the EECP subsystems was assessed for technical risks and barriers. A plan was developed to mitigate the identified risks (Phase II RD&T Plan, October 2000). The potential technical and economic risks to the EECP from Task 2.5 can be mitigated by demonstrating that the end-use products derived from the upgrading of the F-T synthesis total liquid product can meet or exceed current specifications for the

  1. Early vision and visual attention

    Directory of Open Access Journals (Sweden)

    Gvozdenović Vasilije P.

    2003-01-01

    Full Text Available The question whether visual perception is spontaneous, sudden or is running through several phases, mediated by higher cognitive processes, was raised ever since the early work of Gestalt psychologists. In the early 1980s, Treisman proposed the feature integration theory of attention (FIT, based on the findings of neuroscience. Soon after publishing her theory a new scientific approach appeared investigating several visual perception phenomena. The most widely researched were the key constructs of FIT, like types of visual search and the role of the attention. The following review describes the main studies of early vision and visual attention.

  2. A preserved early Ediacaran magmatic arc at the northernmost portion of the Transversal Zone central subprovince of the Borborema Province, Northeastern South America

    Directory of Open Access Journals (Sweden)

    Benjamim Bley de Brito Neves

    Full Text Available ABSTRACT: Magmatic arcs are an essential part of crust-forming events in planet Earth evolution. The aim of this work was to describe an early Ediacaran magmatic arc (ca. 635-580 Ma exposed in the northernmost portion of the Transversal Zone, central subprovince of Borborema Province, northeast Brazil. Our research took advantage of several syntheses by different authors, including theses and dissertations, carried out on magmatic rocks of the study area for the last 30 years. The ca. 750 km long and up to 140 km wide arc, trending ENE-WSW, is preserved to the south of the Patos Lineament, between 35º15' and 42º30'W and 7º15' and 8ºS. About 90 different stocks and batholiths of I-type granitic rocks were mapped along this orogenic zone, preferentially intruding low-grade schists of the Cryogenian-Ediacaran Piancó-Alto Brígida (SPAB belt. Three igneous supersuites are recognized: a epidote-bearing granodiorites and tonalites ("Conceição" type; b high-K calc-alkaline granites ("Itaporanga" type; c biotite granodiorites of trondhjemite affinity ("Serrita" type. A fourth group of peralkalic and shoshonitic rocks occurs to the south of the previous ones, reflecting special tectonic conditions. NNE-SSW trending Paleoproterozoic fold belts, surrounding Archean nuclei, characterize the continental part of the northern lower plate. The oceanic fraction of this lower plate was recycled by subduction and scarce remnants of which may be seen either within the enclosing low-grade schists or as xenoliths within the arc intrusions. The upper continental plate presents WSW-ENE structural trends and is composed of Neoproterozoic fold belts and Paleoproterozoic reworked basement inliers. Available data bear clear evidence of an Ediacaran magmatic arc built at the northern portion of the Transversal Zone in the Borborema Province, northeast Brazil.

  3. Environmental Consequences of Big Nasty Impacts on the Early Earth

    Science.gov (United States)

    Zahnle, Kevin

    2015-01-01

    The geological record of the Archean Earth is spattered with impact spherules from a dozen or so major cosmic collisions involving Earth and asteroids or comets (Lowe, Byerly 1986, 2015). Extrapolation of the documented deposits suggests that most of these impacts were as big or bigger than the Chicxulub event that famously ended the reign of the thunder lizards. As the Archean impacts were greater, the environmental effects were also greater. The number and magnitude of the impacts is bounded by the lunar record. There are no lunar craters bigger than Chicxulub that date to Earth's mid-to-late Archean. Chance dictates that Earth experienced no more than approximately 10 impacts bigger than Chicxulub between 2.5 billion years and 3.5 2.5 billion years, the biggest of which were approximately30-100 times more energetic, comparable to the Orientale impact on the Moon (1x10 (sup 26) joules). To quantify the thermal consequences of big impacts on old Earth, we model the global flow of energy from the impact into the environment. The model presumes that a significant fraction of the impact energy goes into ejecta that interact with the atmosphere. Much of this energy is initially in rock vapor, melt, and high speed particles. (i) The upper atmosphere is heated by ejecta as they reenter the atmosphere. The mix of hot air, rock vapor, and hot silicates cools by thermal radiation. Rock raindrops fall out as the upper atmosphere cools. (ii) The energy balance of the lower atmosphere is set by radiative exchange with the upper atmosphere and with the surface, and by evaporation of seawater. Susequent cooling is governed by condensation of water vapor. (iii) The oceans are heated by thermal radiation and rock rain and cooled by evaporation. Surface waters become hot and salty; if a deep ocean remains it is relatively cool. Subsequently water vapor condenses to replenish the oceans with hot fresh water (how fresh depending on continental weathering, which might be rather rapid

  4. FAA Loran early implementation project

    Science.gov (United States)

    1990-03-01

    The Early Implementation Project (EIP), established by FAA Administrator Admiral : Donald C. Engen, was the initial step in the process of Loran integration into the : National Airsace System (NAS). The EIP was designed to give the FAA and the Loran ...

  5. Hypertension presenting early in pregnancy

    OpenAIRE

    Melvin, Audrey; Kinsley, Brendan

    2015-01-01

    Key Clinical Message Paraganglioma in pregnancy is an exceedingly rare and potentially life?threatening diagnosis. It is important that the clinicians consider secondary causes when women present with hypertension in early pregnancy.

  6. Early onset type 2 diabetes

    DEFF Research Database (Denmark)

    Bo, A; Thomsen, R W; Nielsen, J S

    2018-01-01

    was more frequent and meeting physical activity recommendations less likely in persons with early-onset type 2 DM. CONCLUSIONS: We found a clear age-gradient, with increasing prevalence of clinical and behavioural risk factors the younger the onset age of type 2 DM. Younger persons with early-onset type 2......AIM: To examine the association between early onset of type 2 diabetes (DM) and clinical and behavioural risk factors for later diabetes complications. METHODS: We conducted a cross-sectional study of 5115 persons with incident type 2 DM enrolled during 2010-2015 in the Danish Centre for Strategic...... Research in Type 2 Diabetes-cohort. We compared risk factors at time of diagnosis among those diagnosed at ≤45 years (early-onset) with diagnosis age 46-55, 56-65 (average-onset = reference), 66-75, and >75 years (late-onset). Prevalence ratios (PRs) were computed using Poisson regression. RESULTS: Poor...

  7. [Early management of cerebrovascular accidents].

    Science.gov (United States)

    Libot, Jérômie; Guillon, Benoit

    2013-01-01

    A cerebrovascular accident requires urgent diagnosis and treatment.The management of a stroke must be early and adapted in order to improve the overall clinical outcome and lower the risk of mortality.

  8. Early Identification of Reading Difficulties

    DEFF Research Database (Denmark)

    Poulsen, Mads; Nielsen, Anne-Mette Veber; Juul, Holger

    2017-01-01

    Early screening for reading difficulties before the onset of instruction is desirable because it allows intervention that is targeted at prevention rather than remediation of reading difficulties. However, early screening may be too inaccurate to effectively allocate resources to those who need...... them. The present study compared the accuracy of early screening before the onset of formal reading instruction with late screening six months into the first year of instruction. The study followed 164 Danish students from the end of Grade 0 to the end of Grade 2. Early screening included measures...... of phonemic awareness, rapid naming, letter knowledge, paired associate learning, and reading. Late screening included only reading. Results indicated that reading measures improved substantially as predictors over the first six months of Grade 1, to the point where late reading measures alone provided...

  9. Early Retiree Reinsurance Program Reports

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Early Retiree Reinsurance Program (ERRP) was established by section 1102 of the Patient Protection and Affordable Care Act (the Affordable Care Act) enacted on...

  10. EARLY ENTRANCE COPRODUCTION PLANT

    Energy Technology Data Exchange (ETDEWEB)

    Fred D. Brent; Lalit Shah; Earl Berry; Charles H. Schrader; John Anderson; J. Erwin; Matthew G. Banks; Terry L. Ullman

    2004-01-12

    The overall objective of this project is the three phase development of an Early Entrance Coproduction Plant (EECP) which uses petroleum coke to produce at least one product from at least two of the following three categories: (1) electric power (or heat), (2) fuels, and (3) chemicals using ChevronTexaco's proprietary gasification technology. The objective of Phase I is to determine the feasibility and define the concept for the EECP located at a specific site; develop a Research, Development, and Testing (RD&T) Plan to mitigate technical risks and barriers; and prepare a Preliminary Project Financing Plan. The objective of Phase II is to implement the work as outlined in the Phase I RD&T Plan to enhance the development and commercial acceptance of coproduction technology. The objective of Phase III is to develop an engineering design package and a financing and testing plan for an EECP located at a specific site. The project's intended result is to provide the necessary technical, economic, and environmental information needed by industry to move the EECP forward to detailed design, construction, and operation. The partners in this project are Texaco Energy Systems LLC or TES (a subsidiary of ChevronTexaco), General Electric (GE), Praxair, and Kellogg Brown & Root (KBR) in addition to the U.S. Department of Energy (DOE). TES is providing gasification technology and Fischer-Tropsch (F-T) technology developed by Rentech, GE is providing combustion turbine technology, Praxair is providing air separation technology, and KBR is providing engineering. Each of the EECP subsystems was assessed for technical risks and barriers. A plan was developed to mitigate the identified risks (Phase II RD&T Plan, October 2000). Phase II RD&T Task 2.6 identified as potential technical risks to the EECP the fuel/engine performance and emissions of the F-T diesel fuel products. Hydrotreating the neat F-T diesel product reduces potentially reactive olefins, oxygenates, and acids

  11. Early Intervention in Bipolar Disorder.

    Science.gov (United States)

    Vieta, Eduard; Salagre, Estela; Grande, Iria; Carvalho, André F; Fernandes, Brisa S; Berk, Michael; Birmaher, Boris; Tohen, Mauricio; Suppes, Trisha

    2018-05-01

    Bipolar disorder is a recurrent disorder that affects more than 1% of the world population and usually has its onset during youth. Its chronic course is associated with high rates of morbidity and mortality, making bipolar disorder one of the main causes of disability among young and working-age people. The implementation of early intervention strategies may help to change the outcome of the illness and avert potentially irreversible harm to patients with bipolar disorder, as early phases may be more responsive to treatment and may need less aggressive therapies. Early intervention in bipolar disorder is gaining momentum. Current evidence emerging from longitudinal studies indicates that parental early-onset bipolar disorder is the most consistent risk factor for bipolar disorder. Longitudinal studies also indicate that a full-blown manic episode is often preceded by a variety of prodromal symptoms, particularly subsyndromal manic symptoms, therefore supporting the existence of an at-risk state in bipolar disorder that could be targeted through early intervention. There are also identifiable risk factors that influence the course of bipolar disorder, some of them potentially modifiable. Valid biomarkers or diagnosis tools to help clinicians identify individuals at high risk of conversion to bipolar disorder are still lacking, although there are some promising early results. Pending more solid evidence on the best treatment strategy in early phases of bipolar disorder, physicians should carefully weigh the risks and benefits of each intervention. Further studies will provide the evidence needed to finish shaping the concept of early intervention. AJP AT 175 Remembering Our Past As We Envision Our Future April 1925: Interpretations of Manic-Depressive Phases Earl Bond and G.E. Partridge reviewed a number of patients with manic-depressive illness in search of a unifying endo-psychic conflict. They concluded that understanding either phase of illness was "elusive" and

  12. Early vision and visual attention

    OpenAIRE

    Gvozdenović Vasilije P.

    2003-01-01

    The question whether visual perception is spontaneous, sudden or is running through several phases, mediated by higher cognitive processes, was raised ever since the early work of Gestalt psychologists. In the early 1980s, Treisman proposed the feature integration theory of attention (FIT), based on the findings of neuroscience. Soon after publishing her theory a new scientific approach appeared investigating several visual perception phenomena. The most widely researched were the key constru...

  13. Early diagnosis of breast cancer

    International Nuclear Information System (INIS)

    Semiglazov, V.F.

    1989-01-01

    Modern data are presentd on epidemology etiopathogensis and statistics of breast cancer. Home and international clinical and histological classifications is given. Much attention is paid to the methods for early diagnosis of pretumor diseases and breast cancer: clinical roentgenomammography, thrmography and computerized tomomammography. The role of self-examination in cancer early detection has been analyzed. Special attention is paid to system of detection of minimal and unpalpable form of breast cancer, screening of these tumors. 113 refs.; 60 figs.; 6 tabs

  14. Early presentation of primary glioblastoma.

    Science.gov (United States)

    Faguer, R; Tanguy, J-Y; Rousseau, A; Clavreul, A; Menei, P

    2014-08-01

    Clinical and neuroimaging findings of glioblastomas (GBM) at an early stage have rarely been described and those tumors are most probably under-diagnosed. Furthermore, their genetic alterations, to our knowledge, have never been previously reported. We report the clinical as well as neuroimaging findings of four early cases of patients with GBM. In our series, early stage GBM occurred at a mean age of 57 years. All patients had seizures as their first symptom. In all early stages, MRI showed a hyperintense signal on T2-weighted sequences and an enhancement on GdE-T1WI sequences. A hyperintense signal on diffusion sequences with a low ADC value was also found. These early observed occurrences of GBM developed rapidly and presented the MRI characteristics of classic GBM within a few weeks. The GBM size was multiplied by 32 in one month. Immunohistochemical analysis indicated the de novo nature of these tumors, i.e. absence of mutant IDH1 R132H protein expression, which is a diagnostic marker of low-grade diffuse glioma and secondary GBM. A better knowledge of early GBM presentation would allow a more suitable management of the patients and may improve their prognosis. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  15. [Autism: An early neurodevelopmental disorder].

    Science.gov (United States)

    Bonnet-Brilhault, F

    2017-04-01

    With approximately 67 million individuals affected worldwide, autism spectrum disorder (ASD) is the fastest growing neurodevelopmental disorder (United Nations, 2011), with a prevalence estimated to be 1/100. In France ASD affects approximately 600,000 individuals (from childhood to adulthood, half of whom are also mentally retarded), who thus have a major handicap in communication and in adapting to daily life, which leads autism to be recognized as a national public health priority. ASD is a neurodevelopmental disorder that affects several domains (i.e., socio-emotional, language, sensori-motor, executive functioning). These disorders are expressed early in life with an age of onset around 18 months. Despite evidence suggesting a strong genetic link with ASD, the genetic determinant remains unclear. The clinical picture is characterized by impairments in social interaction and communication and the presence of restrictive and repetitive behaviors (DSM-5, ICD-10). However, in addition to these two main dimensions there is significant comorbidity between ASD and other neurodevelopmental disorders such as attention deficit hyperactivity disorder or with genetic and medical conditions. One of the diagnostic features of ASD is its early emergence: symptoms must begin in early childhood for a diagnosis to be given. Due to brain plasticity, early interventions are essential to facilitate clinical improvement. Therefore, general practitioners and pediatricians are on the front line to detect early signs of ASD and to guide both medical explorations and early rehabilitation. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  16. Early Learner Engagement in the Clinical Workplace

    NARCIS (Netherlands)

    Chen, H.C.

    2015-01-01

    Introduction Recent calls for medical education reform advocate for the integration of knowledge with clinical experience through early clinical immersion. Yet, early learners rarely are invited to participate in workplace activities and early clinical experiences remain largely observational.

  17. Telomere lengthening early in development.

    Science.gov (United States)

    Liu, Lin; Bailey, Susan M; Okuka, Maja; Muñoz, Purificación; Li, Chao; Zhou, Lingjun; Wu, Chao; Czerwiec, Eva; Sandler, Laurel; Seyfang, Andreas; Blasco, Maria A; Keefe, David L

    2007-12-01

    Stem cells and cancer cells maintain telomere length mostly through telomerase. Telomerase activity is high in male germ line and stem cells, but is low or absent in mature oocytes and cleavage stage embryos, and then high again in blastocysts. How early embryos reset telomere length remains poorly understood. Here, we show that oocytes actually have shorter telomeres than somatic cells, but their telomeres lengthen remarkably during early cleavage development. Moreover, parthenogenetically activated oocytes also lengthen their telomeres, thus the capacity to elongate telomeres must reside within oocytes themselves. Notably, telomeres also elongate in the early cleavage embryos of telomerase-null mice, demonstrating that telomerase is unlikely to be responsible for the abrupt lengthening of telomeres in these cells. Coincident with telomere lengthening, extensive telomere sister-chromatid exchange (T-SCE) and colocalization of the DNA recombination proteins Rad50 and TRF1 were observed in early cleavage embryos. Both T-SCE and DNA recombination proteins decrease in blastocyst stage embryos, whereas telomerase activity increases and telomeres elongate only slowly. We suggest that telomeres lengthen during the early cleavage cycles following fertilization through a recombination-based mechanism, and that from the blastocyst stage onwards, telomerase only maintains the telomere length established by this alternative mechanism.

  18. Routine Early Angioplasty after Fibrinolysis

    DEFF Research Database (Denmark)

    Wang, Zhipeng; Liang, Bo; Mei, Qibing

    2009-01-01

    patients in the group that underwent routine early PCI than in the group that received standard treatment received clopidogrel (Ppatients who undergo PCI, as well as in those who do not, is well established,1...... with early beta-blocker therapy is taken into consideration.3 The overall benefit of clopidogrel and beta-blocker therapy could have influenced the outcome in patients who underwent early PCI. These facts leave the conclusion of the TRANSFER-AMI trial still highly uncertain.......To the Editor: Cantor et al. report that there is a significantly reduced rate of ischemic complications among patients with myocardial infarction with ST-segment elevation who are transferred for PCI within 6 hours after fibrinolysis. However, Table 2 of the article shows that significantly more...

  19. Evolution of Earth-like Extrasolar Planetary Atmospheres: Assessing the Atmospheres and Biospheres of Early Earth Analog Planets with a Coupled Atmosphere Biogeochemical Model.

    Science.gov (United States)

    Gebauer, S; Grenfell, J L; Stock, J W; Lehmann, R; Godolt, M; von Paris, P; Rauer, H

    2017-01-01

    remove O 2 that masks its biosphere over a wide range of conditions). Key Words: Early Earth-Proterozoic-Archean-Oxygen-Atmosphere-Biogeochemistry-Photochemistry-Biosignatures-Earth-like planets. Astrobiology 16, 27-54.

  20. Brachytherapy in early prostate cancer--early experience.

    Science.gov (United States)

    Jose, B O; Bailen, J L; Albrink, F H; Steinbock, G S; Cornett, M S; Benson, D C; Schmied, W K; Medley, R N; Spanos, W J; Paris, K J; Koerner, P D; Gatenby, R A; Wilson, D L; Meyer, R

    1999-01-01

    Use of brachytherapy with radioactive seeds in the management of early prostate cancer is commonly used in the United States. The early experience has been reported from the prostate treatment centers in Seattle for the last 10 years. In this manuscript we are reporting our early experience of 150 radioactive seed implantations in early stage prostate cancer using either Iodine 125 or Palladium 103 seeds. The average age of the patient is 66 years and the median Gleason score is 5.4 with a median PSA of 6. A brief description of the evolution of the treatment of prostate cancer as well as the preparation for the seed implantation using the volume study with ultrasound of the prostate, pubic arch study using CT scan of the pelvis and the complete planning using the treatment planning computers are discussed. We also have described the current technique which is used in our experience based on the Seattle guidelines. We plan a follow-up report with the results of the studies with longer follow-up.

  1. Early diagnosis of lung cancer

    International Nuclear Information System (INIS)

    Scherrer, M.

    1982-01-01

    Unanimity does not exist about the utility and organisation of screening procedures for early diagnosis of lung cancer. We describe a low cost structue of screening, requiring only a minimum of compliance from the elderly smoker and ex-smoker. At 4 months interval, radiographs, sputum cytologies and eventual fiberbronchoscopies are realized in all that elderly smokers and ex-smokers which begin to present one of the first early lung cancer signs or symptoms (loss of weight, hemoptoe, thoracic pain and others). (orig.) [de

  2. Shocks in the Early Universe.

    Science.gov (United States)

    Pen, Ue-Li; Turok, Neil

    2016-09-23

    We point out a surprising consequence of the usually assumed initial conditions for cosmological perturbations. Namely, a spectrum of Gaussian, linear, adiabatic, scalar, growing mode perturbations not only creates acoustic oscillations of the kind observed on very large scales today, it also leads to the production of shocks in the radiation fluid of the very early Universe. Shocks cause departures from local thermal equilibrium as well as create vorticity and gravitational waves. For a scale-invariant spectrum and standard model physics, shocks form for temperatures 1  GeVUniverse as early as 10^{-30}  sec after the big bang.

  3. Early-delayed radiation rhombencephalopathy

    International Nuclear Information System (INIS)

    Nightingale, S.; Dawes, P.J.D.K.; Cartlidge, N.E.F.; Newcastle upon Tyne Univ.

    1982-01-01

    A 37-year-old woman developed an early-delayed rhombencephalopathy 7 weeks after completing a course of radiotherapy to a glomus jugulare tumour. The clinical features, comprising nystagmus, skew strabismus, unilateral facial weakness, dysarthria and ataxia, are compared with four previously reported patients with this syndrome. (author)

  4. Early stage fuel cell funding

    International Nuclear Information System (INIS)

    Bergeron, C.

    2004-01-01

    'Full text:' Early stage venture funding requires an in depth understanding of both current and future markets as well as the key technical hurdles that need to be overcome for new technology to commercialize into successful products for mass markets. As the leading fuel cell and hydrogen investor, Chrysalix continuously reviews global trends and new technologies, evaluates them with industry leaders worldwide and tries to match them up with the best possible management teams when selecting its early stage investments. Chrysalix Energy Limited Partnership is an early-stage venture capital firm focusing on fuel cell and related fueling technology companies and is a private equity joint venture between Ballard Power Systems, BASF Venture Capital, The BOC Group, The Boeing Company, Duke Energy, Mitsubishi Corporation and Shell Hydrogen. Operating independently, Chrysalix offers a unique value proposition to its clients throughout the business planning, start-up and operations phases of development. Chrysalix provides early-stage funding to new companies as well as management assistance, technological knowledge, organized networking with industry players and experience in the management of intellectual property. (author)

  5. Early Childhood Intervention in China

    Science.gov (United States)

    Zheng, Yuzhu; Maude, Susan P.; Brotherson, Mary Jane

    2015-01-01

    With rapid economic development and increasing awareness of the importance of early childhood intervention (ECI), China is re-examining its social and educational practices for young children with disabilities. This re-examination may have a significant impact on young children with disabilities in China. It may also set an example for other…

  6. Uganda Early Generation Seed Study

    NARCIS (Netherlands)

    Mastenbroek, A.; Ntare, Bonny

    2016-01-01

    One of the major bottlenecks limiting farmers’ access to good quality seed for food crops in Uganda is the shortage of early generation seed (EGS - breeder and foundation) to produce sufficient quantities of certified and/or quality declared) to satisfy the needs of farmers. A national study was

  7. Early and Late Retirement Exits

    Science.gov (United States)

    Brougham, Ruby R.; Walsh, David A.

    2009-01-01

    The current study proposes that personal need fulfillment (relatedness, generativity, identity, growth, and finances) predicts early and late retirement intentions. The personal needs of 160 full-time older employees were measured by personal goals, job satisfactions, job characteristics, and intrinsic motivation. Results suggest that the personal…

  8. Defeating cancer with early detection

    CERN Document Server

    2003-01-01

    A meeting of scientists and industry experts will hold an open review of the Three Dimension Complete Body Screening System (3D-CBS) on the 1st of July 2003. This new imaging technlogy is potentially powerful and safe enough to offer routine screening of healthy patients for early signs of cancer (1 page).

  9. Boys' Bodies in Early Childhood

    Science.gov (United States)

    Drummond, Murray

    2012-01-01

    This paper is based on qualitative research data from a project investigating early childhood boys' constructions of masculinities in relation to sport, health and the body. The focus group data, with 33 boys, has been collected in each of the boys' first three years at school. It is part of the data that will be collected over eight years with…

  10. Early Childhood Inclusion in Croatia

    Science.gov (United States)

    Ljubešic, Marta; Šimleša, Sanja

    2016-01-01

    This article explains early childhood inclusion in Croatia from its beginnings up to challenges in current policy and practice. The first preschool education for children with disabilities dates back to the 1980s and was provided in special institutions. In the last 10 years, mainstream kindergartens have been enrolling children with disabilities…

  11. Early Childhood Education in Scandinavia.

    Science.gov (United States)

    Austin, Gilbert R.; Dittman, Laura

    This article discusses the move toward greater equality of educational opportunity in Scandinavia with particular emphasis on early childhood education. The increasing demand for preschool education in Denmark, Finland, Norway and Sweden is related to low birth rates together with increased employment of women and the general demand for equality…

  12. Galaxies in the Early Universe

    DEFF Research Database (Denmark)

    Krogager, Jens-Kristian

    Understanding how galaxies evolved from the early Universe through cosmic time is a fundamental part of modern astrophysics. In order to study this evolution it is important to sample the galaxies at various times in a consistent way through time. In regular luminosity selected samples, our...

  13. Glucocorticoids in early rheumatoid arthritis

    NARCIS (Netherlands)

    Everdingen, Amalia A. van

    2002-01-01

    For 50 years, glucocorticoids (GC) are used for symptomatic treatment of rheumatoid arthritis (RA). In the last decade, results from clinical studies of treatment with GC as additional therapy to long-acting antirheumatic drugs in patients with early RA suggested also disease-modifying properties of

  14. Internationalism in Early Adult Education.

    Science.gov (United States)

    Keane, Patrick

    1985-01-01

    Explores the nature and scope of internationalism in early 19th century adult education, using as a context the lyceums and mechanics' institutes of Britain and North America. The contacts involved newspaper and journal accounts, the personal advocacy of former members, written advice from promoters and administrators, and the contributions of…

  15. Management of early pregnancy loss

    NARCIS (Netherlands)

    Graziosi, G. C. M.; Mol, B. W.; Ankum, W. M.; Bruinse, H. W.

    2004-01-01

    Objectives: In order to assess the available evidence on the management of early pregnancy loss, we performed a meta-analysis on the subject. Methods: MEDLINE and EMBASE were searched for randomized studies reporting on the effectiveness of expectant management, misoprostol treatment or curettage.

  16. Physics of the early universe

    International Nuclear Information System (INIS)

    Klinkhamer, F.R.

    1983-01-01

    In this thesis, the author has assembled his papers on elementary particle physics which are of importance for studying cosmology viz. the physics of the early universe. A rather detailed introduction reviewing basic principles and current trends in the relation particle physics/cosmology precedes the papers. (Auth.)

  17. Electromigration early resistance increase measurements

    NARCIS (Netherlands)

    Niehof, J.; Flinn, P.A.; Maloney, T.J.

    1993-01-01

    An early resistance change measurement set-up, using an AC bridge technique, has been developed, and measurements have been performed. Large sample-to-sample variations occur. The characteristic time for the resistance change curve is shorter for resistance increase (under current stress) than for

  18. Early Learning Theories Made Visible

    Science.gov (United States)

    Beloglovsky, Miriam; Daly, Lisa

    2015-01-01

    Go beyond reading about early learning theories and see what they look like in action in modern programs and teacher practices. With classroom vignettes and colorful photographs, this book makes the works of Jean Piaget, Erik Erikson, Lev Vygotsky, Abraham Maslow, John Dewey, Howard Gardner, and Louise Derman-Sparks visible, accessible, and easier…

  19. Early Diagnosis of Breast Cancer.

    Science.gov (United States)

    Wang, Lulu

    2017-07-05

    Early-stage cancer detection could reduce breast cancer death rates significantly in the long-term. The most critical point for best prognosis is to identify early-stage cancer cells. Investigators have studied many breast diagnostic approaches, including mammography, magnetic resonance imaging, ultrasound, computerized tomography, positron emission tomography and biopsy. However, these techniques have some limitations such as being expensive, time consuming and not suitable for young women. Developing a high-sensitive and rapid early-stage breast cancer diagnostic method is urgent. In recent years, investigators have paid their attention in the development of biosensors to detect breast cancer using different biomarkers. Apart from biosensors and biomarkers, microwave imaging techniques have also been intensely studied as a promising diagnostic tool for rapid and cost-effective early-stage breast cancer detection. This paper aims to provide an overview on recent important achievements in breast screening methods (particularly on microwave imaging) and breast biomarkers along with biosensors for rapidly diagnosing breast cancer.

  20. Early Signs of Entrepreneurial Giftedness

    Science.gov (United States)

    Shavinina, Larisa V.

    2008-01-01

    Although successful entrepreneurship is important for the economic prosperity of any society, one should acknowledge that entrepreneurial giftedness is terra incognita from a research viewpoint. This article analyzes early manifestations of entrepreneurial giftedness in the cases of Richard Branson, Michael Dell, and Bill Gates and thus opens a…

  1. FUNdamental Movement in Early Childhood.

    Science.gov (United States)

    Campbell, Linley

    2001-01-01

    Noting that the development of fundamental movement skills is basic to children's motor development, this booklet provides a guide for early childhood educators in planning movement experiences for children between 4 and 8 years. The booklet introduces a wide variety of appropriate practices to promote movement skill acquisition and increased…

  2. IDEA and Early Childhood Inclusion.

    Science.gov (United States)

    Smith, Barbara J.; Rapport, Mary Jane K.

    This paper discusses 1997 amendments to the Individuals with Disabilities Education Act (IDEA) that promote the inclusion of children with disabilities in general early childhood education settings. The evolution of inclusion policy is explored and changes in disability terminology are described. Amended provisions are then explained and include:…

  3. Melanoma early detection and awareness

    DEFF Research Database (Denmark)

    Wainstein, Alberto; Algarra, Salvador Martin; Bastholt, Lars

    2014-01-01

    to increase public awareness and favor early diagnosis. Awareness campaigns, doctor education, and screening of high-risk subjects have all contributed to improve disease outcome in developed countries. The role of primary care physicians is particularly relevant in this regard. Developing countries...

  4. Early Childhood Inclusion in Israel

    Science.gov (United States)

    Al-Yagon, Michal; Aram, Dorit; Margalit, Malka

    2016-01-01

    This article describes conceptual aspects, current policies and practices, and research representing the Israeli perspective regarding early childhood inclusion (ECI) at preschool ages (3-6 years). We review legislative, historical, attitudinal, philosophical, practical, empirical, and cultural issues regarding ECI in Israel. Finally, we focus on…

  5. Reduplication Facilitates Early Word Segmentation

    Science.gov (United States)

    Ota, Mitsuhiko; Skarabela, Barbora

    2018-01-01

    This study explores the possibility that early word segmentation is aided by infants' tendency to segment words with repeated syllables ("reduplication"). Twenty-four nine-month-olds were familiarized with passages containing one novel reduplicated word and one novel non-reduplicated word. Their central fixation times in response to…

  6. Early Childhood Inclusion in Australia

    Science.gov (United States)

    Kemp, Coral R.

    2016-01-01

    From the introduction of early intervention services in Australian in the mid-1970s, the families of children with intellectual and multiple disabilities have been encouraged to enroll their children in local preschools and childcare centers. Children with disabilities have also accessed a range of alternatives to full inclusion, such as reverse…

  7. HPLC: Early and Recent Perspectives.

    Science.gov (United States)

    Karger, Barry L.

    1997-01-01

    Provides a perspective on what it was like in the early days of high-performance liquid chromatography (HPLC) and several of the key developments. Focuses on the advances in HPLC generally, and more specifically for the biological sciences, that were necessary for the method to reach the preeminent stage of today. Contains 20 references. (JRH)

  8. Early Children's Literature and Aging

    Science.gov (United States)

    McGuire, Sandra L.

    2016-01-01

    Increased longevity is a worldwide phenomenon placing emphasis on the need for preparation for life's later years. Today's children will be the older adults of tomorrow. A resource that can help to educate them about aging and prepare them for the long life ahead is early children's literature (Preschool-Primary). This literature can provide…

  9. Vantage point - Early warning flaws.

    Science.gov (United States)

    Swinden, Donna

    2014-08-28

    USING AN EARLY warning score (EWS) system should improve the detection of acutely deteriorating patients. Under such a system, a score is allocated to each of six physiological measurements including respiratory rate and oxygen saturations, which are aggregated to produce an overall score. An aggregated score of seven or higher prompts nursing staff to refer a patient for emergency assessment.

  10. The Integrated Early Childhood Curriculum.

    Science.gov (United States)

    Krogh, Suzanne

    This textbook provides an outline of an integrated curriculum for early childhood education. Part 1 discusses the human element in school: the child and the teacher and child development. Part 2 contains the curriculum itself and covers the subjects of language, mathematics, science, social studies, art, music, and movement. Guidelines provide…

  11. Natural course of early COPD

    Directory of Open Access Journals (Sweden)

    Rhee CK

    2017-02-01

    Full Text Available Chin Kook Rhee,1 Kyungjoo Kim,1 Hyoung Kyu Yoon,2 Jee-Ae Kim,3 Sang Hyun Kim,4 Sang Haak Lee,5 Yong Bum Park,6 Ki-Suck Jung,7 Kwang Ha Yoo,8 Yong Il Hwang7 1Division of Pulmonary, Allergy and Critical Care Medicine, Department of Internal Medicine, Seoul St Mary’s Hospital, 2Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Yeouido St Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul, 3Pharmaceutical Policy Evaluation Research Team, Research Institution, 4Big Data Division, Health Insurance Review and Assessment Service, Wonju, 5Division of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, St Paul’s Hospital, College of Medicine, The Catholic University of Korea, 6Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Internal Medicine, Hallym University Kangdong Sacred Heart Hospital, Seoul, 7Division of Pulmonary, Allergy and Critical Care Medicine, Department of Internal Medicine, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, Anyang, 8Division of Pulmonary, Allergy and Critical Care Medicine, Department of Internal Medicine, Konkuk University School of Medicine, Seoul, Republic of Korea Background and objective: Few studies have examined the natural course of early COPD. The aim of this study was to observe the natural course of early COPD patients. We also aimed to analyze medical utilization and costs for early COPD during a 6-year period. Methods: Patients with early COPD were selected from Korean National Health and Nutrition Examination Survey (KNHANES data. We linked the KNHANES data of patients with early COPD to National Health Insurance data. Results: A total of 2,397 patients were enrolled between 2007 and 2012. The mean forced expiratory volume in 1 second (FEV1 was 78.6%, and the EuroQol five dimensions questionnaire (EQ-5D index value was 0.9. In total, 110 patients utilized health

  12. Famines in Africa: is early warning early enough?

    Directory of Open Access Journals (Sweden)

    Jeeyon Janet Kim

    2012-06-01

    Full Text Available Following the second Sahelian famine in 1984–1985, major investments were made to establish Early Warning Systems. These systems help to ensure that timely warnings and vulnerability information are available to decision makers to anticipate and avert food crises. In the recent crisis in the Horn of Africa, alarming levels of acute malnutrition were documented from March 2010, and by August 2010, an impending food crisis was forecast. Despite these measures, the situation remained unrecognised, and further deteriorated causing malnutrition levels to grow in severity and scope. By the time the United Nations officially declared famine on 20 July 2011, and the humanitarian community sluggishly went into response mode, levels of malnutrition and mortality exceeded catastrophic levels. At this time, an estimated 11 million people were in desperate and immediate need for food. With warnings of food crises in the Sahel, South Sudan, and forecast of the drought returning to the Horn, there is an immediate need to institutionalize change in the health response during humanitarian emergencies. Early warning systems are only effective if they trigger an early response.

  13. Pompe Disease: Early Diagnosis and Early Treatment Make a Difference

    Directory of Open Access Journals (Sweden)

    Yin-Hsiu Chien

    2013-08-01

    Full Text Available Pompe disease (glycogen storage disease type II or acid maltase deficiency is a lysosomal disorder in which acid α-glucosidase (GAA deficiencies lead to intralysosomal accumulation of glycogen in all tissues; most notably in skeletal muscles. Both the patient's age at the onset of Pompe disease symptoms and the rate of deterioration caused by the disease can vary considerably. In classical infant-onset Pompe disease (IOPD, symptoms start very early in life, and death occurs soon afterward if the disease remains untreated. In later-onset Pompe disease, symptoms are slower to appear, and patients often progress to wheelchair confinement and eventual respiratory failure. A diagnosis can be made by screening for GAA in dried blood samples, followed either by GAA assessment in lymphocytes or in fibroblasts or by the genetic analysis of mutations. Treatment by enzyme replacement therapy (ERT with alglucosidase alfa was approved for human use in 2006. In classical IOPD, treatment significantly lengthens survival and improves motor development and cardiac function. The sooner ERT begins, the better are the results. Newborn screening aims to take advantage of different technologies for diagnosing and treating newborns early on and it yields better outcomes. However, newborns diagnosed early and other long-term survivors may encounter fresh problems, making up a new phenotype of IOPD patients. Further modifications of the treatment, such as a decrease in immune responses to ERT, a higher dosage, a better uptake formulation, and gene therapy delivered locally or systemically are being explored.

  14. Abnormal early cleavage events predict early embryo demise: sperm oxidative stress and early abnormal cleavage.

    Science.gov (United States)

    Burruel, Victoria; Klooster, Katie; Barker, Christopher M; Pera, Renee Reijo; Meyers, Stuart

    2014-10-13

    Human embryos resulting from abnormal early cleavage can result in aneuploidy and failure to develop normally to the blastocyst stage. The nature of paternal influence on early embryo development has not been directly demonstrated although many studies have suggested effects from spermatozoal chromatin packaging, DNA damage, centriolar and mitotic spindle integrity, and plasma membrane integrity. The goal of this study was to determine whether early developmental events were affected by oxidative damage to the fertilizing sperm. Survival analysis was used to compare patterns of blastocyst formation based on P2 duration. Kaplan-Meier survival curves demonstrate that relatively few embryos with short (P2 times reached blastocysts, and the two curves diverged beginning on day 4, with nearly all of the embryos with longer P2 times reaching blastocysts by day 6 (p < .01). We determined that duration of the 2nd to 3rd mitoses were sensitive periods in the presence of spermatozoal oxidative stress. Embryos that displayed either too long or too short cytokineses demonstrated an increased failure to reach blastocyst stage and therefore survive for further development. Although paternal-derived gene expression occurs later in development, this study suggests a specific role in early mitosis that is highly influenced by paternal factors.

  15. Do schizophrenia patients age early?

    Science.gov (United States)

    Shivakumar, Venkataram; Kalmady, Sunil V; Venkatasubramanian, Ganesan; Ravi, Vasanthapuram; Gangadhar, Bangalore N

    2014-08-01

    The etiopathogenesis of schizophrenia is poorly understood. Within the proposed "neurodegeneration paradigm", observations have been put forth for "accelerated aging" in this disorder. This proposition is largely based on the neuroscience research that demonstrates progressive changes in brain as well as other systemic abnormalities supportive of faster aging process in patients with this disorder. In this review, we have summarized the literature related to the concept of early aging in schizophrenia. These studies include P300 abnormalities & visual motion discrimination, neuroimaging findings, telomere dynamics as well as neuropathology of related brain regions. We also propose a role of vitamin D, neuroimmunological changes and elevated oxidative stress as well as mitochondrial dysfunction in addition to the above factors with 'vitamin-D deficiency' as the central paradox. Put together, the evidence supporting early aging in schizophrenia is compelling and this requires further systematic studies. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Nanotechnology for Early Cancer Detection

    Directory of Open Access Journals (Sweden)

    Joon Won Park

    2010-01-01

    Full Text Available Vast numbers of studies and developments in the nanotechnology area have been conducted and many nanomaterials have been utilized to detect cancers at early stages. Nanomaterials have unique physical, optical and electrical properties that have proven to be very useful in sensing. Quantum dots, gold nanoparticles, magnetic nanoparticles, carbon nanotubes, gold nanowires and many other materials have been developed over the years, alongside the discovery of a wide range of biomarkers to lower the detection limit of cancer biomarkers. Proteins, antibody fragments, DNA fragments, and RNA fragments are the base of cancer biomarkers and have been used as targets in cancer detection and monitoring. It is highly anticipated that in the near future, we might be able to detect cancer at a very early stage, providing a much higher chance of treatment.

  17. Early intervention services in psychosis

    DEFF Research Database (Denmark)

    Csillag, Claudio; Nordentoft, Merete; Mizuno, Masafumi

    2016-01-01

    AIM: Early intervention (EI) in psychosis is a comprehensive and evidence-based approach aimed at detection and treatment of psychotic symptoms in their early stages. This paper presents core features and noteworthy aspects of the evidence basis and limitations of EI, the importance of programme ....... Wider dissemination of EI services will probably benefit from better integration of potential funders, promotion of joint targets and shared financial or budgetary incentives....... overcome these difficulties. CONCLUSIONS: Funding for mental health in general and for EI services appears low relative to need. One key argument for better funding for EI can be found in its favourable cost-effectiveness, but not all stakeholders beyond mental health administrators are aware of this...

  18. Cosmology and the early universe

    CERN Document Server

    Di Bari, Pasquale

    2018-01-01

    This book discusses cosmology from both an observational and a strong theoretical perspective. The first part focuses on gravitation, notably the expansion of the universe and determination of cosmological parameters, before moving onto the main emphasis of the book, the physics of the early universe, and the connections between cosmological models and particle physics. Readers will gain a comprehensive account of cosmology and the latest observational results, without requiring prior knowledge of relativistic theories, making the text ideal for students.

  19. Early laparotomy after lung transplantation

    DEFF Research Database (Denmark)

    Bredahl, Pia; Zemtsovski, Mikhail; Perch, Michael

    2014-01-01

    BACKGROUND: Gastrointestinal complications after lung transplantation have been reported with incidence rates ranging from 3% to 51%, but the reasons are poorly understood. We aimed to investigate the correlations between pulmonary diseases leading to lung transplantation and early gastrointestinal...... for time on mechanical ventilation. Among pulmonary diseases and demographics of the patients, no other risk factors were identified for laparotomy. CONCLUSIONS: A1AD was the only significant risk factor identified for gastrointestinal complications that required laparotomy within 3 months after lung...

  20. The early days of incineration

    Energy Technology Data Exchange (ETDEWEB)

    Valenti, M.

    1995-05-01

    Landfills reaching capacity, beaches fouled with trash, neighborhood residents protesting waste disposal sites in their backyards, and municipalities forced to recycle. Sound familiar? These issues might have been taken from today`s headlines, but they were also problems facing mechanical engineers a century ago. Conditions such as these were what led engineers to design the first incinerators for reducing the volume of municipal garbage, as well as for producing heat and electricity. The paper discusses these early days.

  1. Interpersonal relationships in early adulthood

    OpenAIRE

    Kočevar, Zala

    2014-01-01

    Interpersonal relationships in early adulthood, in people aged 25 to 30 vary considerably among individuals. Some place emphasis on partnership, and others on relations with friends. Even the relationship with parents and siblings are experienced by young adults in a variety of ways. Some have frequent and regular contact with their parents while some no longer have any relationship with their parents. These are two frequent situations hiding much more in between. Relationships are complex an...

  2. Petrogenesis of 3.15 Ga old Banasandra komatiites from the Dharwar craton, India: Implications for early mantle heterogeneity

    Directory of Open Access Journals (Sweden)

    J.M. Maya

    2017-05-01

    Full Text Available Spinifex-textured, magnesian (MgO >25 wt.% komatiites from Mesoarchean Banasandra greenstone belt of the Sargur Group in the Dharwar craton, India were analysed for major and trace elements and 147,146Sm-143,142Nd systematics to constrain age, petrogenesis and to understand the evolution of Archean mantle. Major and trace element ratios such as CaO/Al2O3, Al2O3/TiO2, Gd/Yb, La/Nb and Nb/Y suggest aluminium undepleted to enriched compositional range for these komatiites. The depth of melting is estimated to be varying from 120 to 240 km and trace-element modelling indicates that the mantle source would have undergone multiple episodes of melting prior to the generation of magmas parental to these komatiites. Ten samples of these komatiites together with the published results of four samples from the same belt yield 147Sm-143Nd isochron age of ca. 3.14 Ga with an initial ɛNd(t value of +3.5. High precision measurements of 142Nd/144Nd ratios were carried out for six komatiite samples along with standards AMES and La Jolla. All results are within uncertainties of the terrestrial samples. The absence of 142Nd/144Nd anomaly indicates that the source of these komatiites formed after the extinction of 146Sm, i.e. 4.3 Ga ago. In order to evolve to the high ɛNd(t value of +3.5 by 3.14 Ga the time-integrated ratio of 147Sm/144Nd should be 0.2178 at the minimum. This is higher than the ratios estimated, so far, for mantle during that time. These results indicate at least two events of mantle differentiation starting with the chondritic composition of the mantle. The first event occurred very early at ∼4.53 Ga to create a global early depleted reservoir with superchondritic Sm/Nd ratio. The source of Isua greenstone rocks with positive 142Nd anomaly was depleted during a second differentiation within the life time of 146Sm, i.e. prior to 4.46 Ga. The source mantle of the Banasandra komatiite was a result of a differentiation event that occurred

  3. Supporting Families through Early Intervention

    Directory of Open Access Journals (Sweden)

    Roy McConkey

    2003-09-01

    Full Text Available Internationally early intervention programmes for infants and preschoolers with disabilities have proved to be remarkably successful. In many countries, they began with teachers for visually impaired or hearing impaired children visiting the family home to teach parents how they could overcome the child's impairments. The logic of early intervention was inequitable. For example, the sooner children with visual impairments learnt to be independently mobile, then the greater their potential to learn and to kad an ordinary life. In time, this philosophy was extended to children with neurological and developmental delays, such as mental retardation, although success could be variable. In part, many different factors contributed to this variability: the form the interventions took, the extent of family involvement in the intervention and the lack of sensitivity of the measures used to assess a child's progress, to name but three. Perhaps the most extensive and intensive Early intervention schemes have been in the United States with their Head Start programmes. They were aimed at promoting the educational potential of preschoolers from deprived socio - economic backgrounds. Although the first phase of programmes had varying success, those in the second phase yielded impressive results which were mainly attributed to a greater focus on parental participation and links forged with the school system. Recently in developing countries, priority has been given to establishing early intervention as a means of creating new styles of family-based and community-based service in these countries in contrast to the hospital or institutional-services that were a legacy from a previous generation. Although formal evaluations are largely lacking, informal reports have been broadly enthusiastic. In sum, early intervention is no longer a new approach to developmental disabilities. It is an approach of proven effectiveness with children who have different impairments

  4. Early detection of first-episode psychosis

    DEFF Research Database (Denmark)

    Larsen, Tor K; Melle, Ingrid; Auestad, Bjørn

    2006-01-01

    Early intervention is assumed to improve outcome in first-episode psychosis, but this has not been proven.......Early intervention is assumed to improve outcome in first-episode psychosis, but this has not been proven....

  5. Early Identification of Psychosis: A Primer

    OpenAIRE

    Early Psychosis Initiative of British Columbia

    2000-01-01

    This document is an educational resource concerning the early identification of psychosis. Primary topics addressed include: an outline of the importance of early intervention; signs and symptoms of psychosis; and strategies for recognizing psychosis.  

  6. Peering Into an Early Galaxy

    Science.gov (United States)

    Kohler, Susanna

    2018-04-01

    Thirteen billion years ago, early galaxies ionized the gas around them, producing some of the first light that brought our universe out of its dark ages. Now the Atacama Large Millimeter/submillimeter Array (ALMA) has provided one of the first detailed looks into the interior of one of these early, distant galaxies.Sources of LightArtists illustration of the reionization of the universe (time progresses left to right), in which ionized bubbles that form around the first sources of light eventually overlap to form the fully ionized universe we observe today. [Avi Loeb/Scientific American]For the first roughly hundred million years of its existence, our universe expanded in relative darkness there were no sources of light at that time besides the cosmic microwave background. But as mass started to condense to form the first objects, these objects eventually shone as the earliest luminous sources, contributing to the reionization of the universe.To learn about the early production of light in the universe, our best bet is to study in detail the earliest luminous sources stars, galaxies, or quasars that we can hunt down. One ideal target is the galaxy COSMOS Redshift 7, known as CR7 for short.Targeting CR7CR7 is one of the oldest, most distant galaxies known, lying at a redshift of z 6.6. Its discovery in 2015 and subsequent observations of bright, ultraviolet-emitting clumps within it have led to broad speculation about the source of its emission. Does this galaxy host an active nucleus? Or could it perhaps contain the long-theorized first generation of stars, metal-free Population III stars?To determine the nature of CR7 and the other early galaxies that contributed to reionization, we need to explore their gas and dust in detail a daunting task for such distant sources! Conveniently, this is a challenge that is now made possible by ALMAs incredible capabilities. In a new publication led by Jorryt Matthee (Leiden University, the Netherlands), a team of scientists now

  7. THE IMPORTANCE OF INVESTMENTS IN EARLY EDUCATION

    OpenAIRE

    DUMITRESCU Alexandra; CONSTANTINESCU Adrian; TACHE Ileana

    2012-01-01

    The early education is analyzed as being the most profitable investment in education (R. Cuhna). early education supports later learning opportunities. The economic dimension of early education takes into account the fact that the necessary investment for a child to benefit from early education services is rather low when looking at the cost (both economic and social) generated by a child who misses this education level, not necessarily because of the late education start but because of the l...

  8. Early diagnosis of the Spondyloarthropathies

    International Nuclear Information System (INIS)

    Gonzalez Naranjo, Luis Alonso; Londono, John D; Valle, Rafael Raul

    2005-01-01

    Spondyloarthropathies are a cluster of chronic inflammatory diseases that primarily include ankylosing spondylitis, reactive arthritis, psoriatic arthritis; arthritis associated with inflammatory bowel diseases and undifferentiated spondyloarthropathies. The most common subgroups of spondyloarthropathies are ankylosing spondylitis and undifferentiated spondyloarthropathy. The diagnosis of ankylosing spondylitis is mainly based on unequivocal radiographic sacroiliitis of at least grade 2 bilaterally or grade 3 unilaterally. How ever, in the early phase of disease, conventional radiographs are often too insensitive to show sacroiliitis and it usually takes several years for definite radiographic sacroiliitis to evolve. Thus, the diagnosis of ankylosing spondylitis is a commonly delayed by 8 to 11 years after the onset of symptoms. As a result, diagnosing axial spondyloarthropathy in the absence of radiographic sacroiliitis is very difficult to rheumatologists. In the early phase of disease, HLA B27 test and magnetic resonance imaging of sacroiliac joints may be helpful to the early diagnosis. In the presence of chronic low back pain the probability of axial spondyloarthropathy is about 5% and is about 14% if the back pain is inflammatory. The presence of = 3 features of spondyloarthropathy (heel pain, uveitis, dactylitis, positive family history, alternating buttock pain, psoriasis, inflammatory bowel disease, asymmetrical arthritis, positive response to anti-inflammatory drugs) increase the probability of axial spondyloarthropathy to 90%. Both, the positive HLA B27 and magnetic resonance imaging with signs of sacroiliitis increase the probability of spondyloarthropathy, particularly in patients without spondyloarthropathies features or with only 1 or 2 features. Since ankylosing spondylitis in association with psoriasis and inflammatory bowel disease is often HLA B27 negative, this test is of limited value under theses circumstances. Is important to consider that

  9. Observations of Early Optical Afterglows

    OpenAIRE

    Roming, Peter W. A.; Mason, Keith O.

    2006-01-01

    The Swift Ultra-Violet/Optical Telescope (UVOT) has performed extensive follow-up on 71 Swift Burst Alert Telescope triggered gamma-ray bursts (GRBs) in its first ten months of operations. In this paper, we discuss some of the UV and optical properties of UVOT detected afterglows such as XRF 050406, the bright GRB 050525A, the high redshift GRB 050730, the early flaring GRB 050801, and others. We also discuss some of the implications of why 75% of GRB afterglows observed by UVOT in less than ...

  10. Early discharge hospital at home.

    Science.gov (United States)

    Gonçalves-Bradley, Daniela C; Iliffe, Steve; Doll, Helen A; Broad, Joanna; Gladman, John; Langhorne, Peter; Richards, Suzanne H; Shepperd, Sasha

    2017-06-26

    Early discharge hospital at home is a service that provides active treatment by healthcare professionals in the patient's home for a condition that otherwise would require acute hospital inpatient care. This is an update of a Cochrane review. To determine the effectiveness and cost of managing patients with early discharge hospital at home compared with inpatient hospital care. We searched the following databases to 9 January 2017: the Cochrane Effective Practice and Organisation of Care Group (EPOC) register, Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, CINAHL, and EconLit. We searched clinical trials registries. Randomised trials comparing early discharge hospital at home with acute hospital inpatient care for adults. We excluded obstetric, paediatric and mental health hospital at home schemes.   DATA COLLECTION AND ANALYSIS: We followed the standard methodological procedures expected by Cochrane and EPOC. We used the GRADE approach to assess the certainty of the body of evidence for the most important outcomes. We included 32 trials (N = 4746), six of them new for this update, mainly conducted in high-income countries. We judged most of the studies to have a low or unclear risk of bias. The intervention was delivered by hospital outreach services (17 trials), community-based services (11 trials), and was co-ordinated by a hospital-based stroke team or physician in conjunction with community-based services in four trials.Studies recruiting people recovering from strokeEarly discharge hospital at home probably makes little or no difference to mortality at three to six months (risk ratio (RR) 0.92, 95% confidence interval (CI) 0.57 to 1.48, N = 1114, 11 trials, moderate-certainty evidence) and may make little or no difference to the risk of hospital readmission (RR 1.09, 95% CI 0.71 to 1.66, N = 345, 5 trials, low-certainty evidence). Hospital at home may lower the risk of living in institutional setting at six months (RR 0.63, 96% CI

  11. Early detection of congenital syphilis

    Directory of Open Access Journals (Sweden)

    Nagalakshmi Chowdhary

    2014-01-01

    Full Text Available Late congenital syphilis is a very rare clinical entity, and its early diagnosis and treatment is essential. Dental findings often provide valuable evidence for the diagnosis of late congenital syphilis. It occurs due to the transmission of the disease from an infected mother to her fetus through placenta. This long forgotten disease continues to effect pregnant women resulting in perinatal morbidity and mortality. Congenital syphilis is a preventable disease, and its presence reflects a failure of prenatal care delivery system, as well as syphilis control programs. We are reporting a case of late congenital syphilis with only Hutchinson′s teeth.

  12. Early history of military radiology

    International Nuclear Information System (INIS)

    Eisenberg, R.L.

    1991-01-01

    This paper reports that soon after Roentgen's discovery, physicians in the armed services of the major powers grasped the importance of x-ray sin military surgery. By May of 1896, radiographic examinations were being performed on Italian soldiers returning from the ill-fated Ethiopian campaign. Initially, radiographs were used for foreign body localization and the detection of fractures; later, a full range of diagnostic services was offered. The early challenges of obtaining x-ray examinations in the field - fragility of tubes and plates, mobility of machines and patients, and unpredictability of radiation dosage - became the basis for innovations that would fundamentally alter the daily practice of radiology in civilian life

  13. Examining Text Complexity in the Early Grades

    Science.gov (United States)

    Fitzgerald, Jill; Elmore, Jeff; Hiebert, Elfrieda H.; Koons, Heather H.; Bowen, Kimberly; Sanford-Moore, Eleanor E.; Stenner, A. Jackson

    2016-01-01

    The Common Core raises the stature of texts to new heights, creating a hubbub. The fuss is especially messy at the early grades, where children are expected to read more complex texts than in the past. But early-grades teachers have been given little actionable guidance about text complexity. The authors recently examined early-grades texts to…

  14. Ethics dilemmas of early detection of obesity

    DEFF Research Database (Denmark)

    Vallgårda, Signild

    2016-01-01

    Aim: To discuss the ethics dilemmas of the early detection of overweight and obesity. Methods: Analysis of the ethical aspects of early detection. Results: The early detection of overweight and obesity entails a number of ethical dilemmas because it may both be helpful and harmful. It may help...

  15. Early identification and intervention in cerebral palsy

    DEFF Research Database (Denmark)

    Herskind, Anna; Greisen, Gorm; Nielsen, Jens Bo

    2015-01-01

    Infants with possible cerebral palsy (CP) are commonly assumed to benefit from early diagnosis and early intervention, but substantial evidence for this is lacking. There is no consensus in the literature on a definition of 'early', but this review focuses on interventions initiated within...

  16. Early Childhood Inclusion in the United Kingdom

    Science.gov (United States)

    Blackburn, Carolyn

    2016-01-01

    A policy-to-practice paper is presented of early childhood inclusion in England. The article aims to report the benefits of early intervention services and early childhood inclusion for children with special educational needs and disabilities (SEND), document the chronology of policy development, and discuss research evidence about…

  17. Early Learning and Educational Technology Policy Brief

    Science.gov (United States)

    Lee, Joan

    2016-01-01

    Recognizing the growth of technology use in early learning settings, the U.S. Department of Education and U.S. Department of Health and Human Services collaborated in the development of the "Early Learning and Educational Technology Policy Brief" to promote developmentally appropriate use of technology in homes and early learning…

  18. Early infection and prognosis after acute stroke

    DEFF Research Database (Denmark)

    Kammersgaard, L P; Jørgensen, H S; Reith, J

    2001-01-01

    Infection is a frequent complication in the early course of acute stroke and may adversely affect stroke outcome. In the present study, we investigate early infection developing in patients within 3 days of admission to the hospital and its independent relation to recovery and stroke outcome....... In addition, we identify predictors for early infections, infection subtypes, and their relation to initial stroke severity....

  19. Early Smoking, Education, and Labor Market Performance

    NARCIS (Netherlands)

    Palali, Ali

    2015-01-01

    This study investigates the effects of early smoking on educational attainment and labor market performance. The results show that early smoking adversely affects educational attainment and initial labor market performance, but only for males. The effect of early smoking on initial labor market

  20. Early Archaean collapse basins, a habitat for early bacterial life.

    Science.gov (United States)

    Nijman, W.

    For a better definition of the sedimentary environment in which early life may have flourished during the early Archaean, understanding of the basin geometry in terms of shape, depth, and fill is a prerequisite. The basin fill is the easiest to approach, namely from the well exposed, low-grade metamorphic 3.4 - 3.5 Ga rock successions in the greenstone belts of the east Pilbara (Coppin Gap Greenstone Belt and North Pole Dome) in West Australia and of the Barberton Greenstone Belt (Buck Ridge volcano-sedimentary complex) in South Africa. They consist of mafic to ultramafic volcanic rocks, largely pillow basalts, with distinct intercalations of intermediate to felsic intrusive and volcanic rocks and of silicious sediments. The, partly volcaniclastic, silicious sediments of the Buck Ridge and North Pole volcano-sedimentary complexes form a regressive-transgressive sequence. They were deposited close to base level, and experienced occasional emersion. Both North Pole Chert and the chert of the Kittys Gap volcano-sedimentary complex in the Coppin Gap Greenstone Belt preserve the flat-and-channel architecture of a shallow tidal environment. Thickness and facies distribution appear to be genetically linked to systems, i.e. arrays, of syn-depositionally active, extensional faults. Structures at the rear, front and bottoms of these fault arrays, and the fault vergence from the basin margin towards the centre characterize the basins as due to surficial crustal collapse. Observations in the Pilbara craton point to a non-linear plan view and persistence for the basin-defining fault patterns over up to 50 Ma, during which several of these fault arrays became superposed. The faults linked high-crustal level felsic intrusions within the overall mafic rock suite via porphyry pipes, black chert veins and inferred hydrothermal circulations with the overlying felsic lavas, and more importantly, with the cherty sediments. Where such veins surfaced, high-energy breccias, and in the

  1. Early occurring and continuing effects

    International Nuclear Information System (INIS)

    Scott, B.R.; Hahn, F.F.

    1985-01-01

    This chapter deals with health-risk estimates for early and continuing effects of exposure to ionizing radiations that could be associated with light water nuclear power plants accidents. Early and continuing effects considered are nonneoplastic diseases and symptoms that normally occur soon after radiation exposure, but may also occur after years have passed. They are generally associated with relatively high (greater than 1 Gy) doses. For most of the effects considered, there is a practical dose threshold. Organs of primary interest, because of their high sensitivity or the likelihood of receiving a large radiation dose, are bone marrow, gastrointestinal tract, thyroid glands, lungs, skin, gonads, and eyes. In utero exposure of the fetus is also considered. New data and modeling techniques available since publication of the Reactor Safety Study (WASH 1400, 1975) were used along with data cited in the Study to develop improved health-risk models for morbidity and mortality. The new models are applicable to a broader range of accident scenarios, provide a more detailed treatment of dose protraction effects, and include morbidity effects not considered in the Reactor Safety Study. 115 references, 20 figures, 19 tables

  2. Cerebrovascular Diseases and Early Seizure

    Directory of Open Access Journals (Sweden)

    Ayşegül Gündüz

    2006-08-01

    Full Text Available OBJECTIVE: Cerebrovascular disease is one of the important causes of seizures and epilepsy among the advanced age group. Seziures are found to be associated with lesion localization and size in previous studies. METHODS: Here, we aimed to detect prevelance of seizure, relation of seizure and lesion localization, and observed seizure types. RESULTS: Three hundred seventy eight patients with ischemic cerebrovascular disease or intraparenchymal hemorrhage who were followed in Cerrahpasa IVIedical School clinic were studied retrospectively and probability of seizure occurence within 1 month after stroke was evaluated. CONCLUSION: Among 378 patients hospitalized by acute stroke, 339 were diagnosed as ischemic cerebrovascular disease and 39 (10.3% had primary intraparenchymal hematoma. Seizures were observed in 16 patients (4.2%, 2 (%5.1 in intraparenchymal hematoma group and 14 (%4.1 in ischemic cerebrovascular disease. Early seizures were detected in 33% of patients with anterior cerebral artery, in 6.8% of posterior cerebral artery and in 3.3% of middle cerebral artery infarcts and in three patients out of 12 who were known to have epilepsy. Seizure types were secondarily generalised tonic-clonic seizure in nine cases (57%. Among whole group status epilepticus was observed in four patients (1.1%. Conclusion: Early seizure rates are found to be high among patients with anterior cerebral artery infarct and known epilepsy

  3. EGU's Early Career Scientists Network

    Science.gov (United States)

    Roberts Artal, L.; Rietbroek, R.

    2017-12-01

    The EGU encourages early career scientists (ECS) to become involved in interdisciplinary research in the Earth, planetary and space sciences, through sessions, social events and short courses at the annual General Assembly in April and throughout the year. Through division-level representatives, all ECS members can have direct input into matters of the division. A Union-wide representative, who sits on the EGU Council, ensures that ECS are heard at a higher level in the Union too. After a brief introduction as to how the network is organised and structured, this presentation will discuss how EGU ECS activities have been tailored to the needs of ECS members and how those needs have been identified. Reaching and communicating opportunities to ECS remains an ongoing challenge; they will be discussed in this presentation too, as well as some thoughts on how to make them more effective. Finally, the service offered to EGU ECS members would certainly benefit from building links and collaboration with other early career networks in the geosciences. This presentation will outline some of our efforts in that direction and the challenges that remain.

  4. Overview of Play: Its Uses and Importance in Early Intervention/Early Childhood Special Education

    Science.gov (United States)

    Lifter, Karin; Foster-Sanda, Suzanne; Arzamarski, Caley; Briesch, Jacquelyn; McClure, Ellen

    2011-01-01

    Play is a natural activity of early childhood, which has great relevance to the fields of early intervention, early childhood special education, and early childhood education. Within these fields, ongoing tensions persist in how play is described and used. These tensions compromise activities of assessment, intervention, and curriculum development…

  5. Recent Coverage of Early Childhood Education Approaches in Open Access Early Childhood Journals

    Science.gov (United States)

    Keskin, Burhanettin

    2016-01-01

    A content analysis of the coverage of the major approaches to early childhood education in the early childhood research journals, published between 2010 and 2014, that are early childhood research oriented and have free online access were investigated. Among 21 journals in early childhood education, two journals were selected for the content…

  6. Ultrasonographic findings of early abortion: suggested predictors

    International Nuclear Information System (INIS)

    Jun, Soon Ae; Ahn, Myoung Ock; Cha, Kwang Yul; Lee, Young Doo

    1992-01-01

    To investigate predictable ultrasonographic findings of early abortion. To investigate objective rules for the screening of abortion. Ultrasonographic examination of 111 early pregnancies between the sixth and ninth week in women who had regular 28 day menstrual cycles was performed. Ultrasonographic measurements of the gestational sac, crown rump length and fetal heart rate were performed using a linear array real time transducer with doppler ultrasonogram. All measurements of 17 early abortions were compared to those of 94 normal pregnancies. Most of early aborted pregnancies were classified correctly by discriminant analysis with G-SAC and CRL (G-SAC=0.5 CRL + 15, sensitivity 76.5%, specificity 96.8%). With the addition of FHR, 94.1% of early abortions could be predicted. In conclusion, ultrasonographic findings of early intrauterine growth retardation, small gestational sac and bradycardia can be predictable signs suggestive of poor prognosis of early pregnancies

  7. Early School Leaving in Scandinavia

    DEFF Research Database (Denmark)

    Jakobsen, Vibeke; Bäckman, Olof; Lorentzen, Thomas

    2015-01-01

    countries and find the highest vocational track dropout rates in Norway and the lowest in Finland. The results indicate that the relative labour market effect of dropping out from a vocational track is most detrimental in Norway. It is also in Norway that we find the greatest gender differences......The article explores the extent to which the organization of vocational tracks in upper secondary school affects the labour market risks associated with early school exit. The Nordic countries share many features, but the upper secondary school systems differ significantly in how their vocational...... tracks are organized. Denmark and Norway have dual vocational tracks, that is, they combine school-based education and workplace apprenticeships, whereas in Finland and Sweden they are primarily school based. We analyse administrative longitudinal data from the mid-1990s to the mid-2000s in the four...

  8. Excess Early Mortality in Schizophrenia

    DEFF Research Database (Denmark)

    Laursen, Thomas Munk; Nordentoft, Merete; Mortensen, Preben Bo

    2014-01-01

    Schizophrenia is often referred to as one of the most severe mental disorders, primarily because of the very high mortality rates of those with the disorder. This article reviews the literature on excess early mortality in persons with schizophrenia and suggests reasons for the high mortality...... as well as possible ways to reduce it. Persons with schizophrenia have an exceptionally short life expectancy. High mortality is found in all age groups, resulting in a life expectancy of approximately 20 years below that of the general population. Evidence suggests that persons with schizophrenia may...... not have seen the same improvement in life expectancy as the general population during the past decades. Thus, the mortality gap not only persists but may actually have increased. The most urgent research agenda concerns primary candidates for modifiable risk factors contributing to this excess mortality...

  9. LEP vacuum chamber, early prototype

    CERN Multimedia

    CERN PhotoLab

    1978-01-01

    The structure of LEP, with long bending magnets and little access to the vacuum chamber between them, required distributed pumping. This is an early prototype for the LEP vacuum chamber, made from extruded aluminium. The main opening is for the beam. The small channel to the right is for cooling water, to carry away the heat deposited by the synchroton radiation from the beam. The 4 slots in the channel to the left house the strip-shaped ion-getter pumps (see 7810255). The ion-getter pumps depended on the magnetic field of the bending magnets, too low at injection energy for the pumps to function well. Also, a different design was required outside the bending magnets. This design was therefore abandoned, in favour of a thermal getter pump (see 8301153 and 8305170).

  10. How early and how long?

    Directory of Open Access Journals (Sweden)

    Mette Løvgren

    2012-01-01

    Full Text Available Abstract: Day care centres have become a normal part of Norwegian childhood, even among quite small children. In 1970 less than 3 per cent of Norwegian children of pre-school were enrolled. At the end of 2009 as much as 70 per cent of children aged 12 to 24 months were enrolled and for 90 per cent of them a full day stay had been arranged. Norwegian children with small children opt for an early start at a day care centre. However, the day care centre employees do not share the same views as the users of the services they provide. Only one third of them express the opinion that children may start at the age of one and have a full day stay at this age. The article discusses this discrepancy between the users and providers of public financed day care.

  11. LHCb Early Career Scientist Awards

    CERN Multimedia

    Patrick Koppenburg for the LHCb Collaboration

    2016-01-01

    On 15 September 2016, the LHCb collaboration awarded the first set of prizes for outstanding contributions of early career scientists.   From left to right: Guy Wilkinson (LHCb spokesperson), Sascha Stahl, Kevin Dungs, Tim Head, Roel Aaij, Conor Fitzpatrick, Claire Prouvé, Patrick Koppenburg (chair of committee) and Sean Benson. Twenty-five nominations were submitted and considered by the committee, and 5 prizes were awarded to teams or individuals for works that had a significant impact within the last year. The awardees are: Roel Aaij, Sean Benson, Conor Fitzpatrick, Rosen Matev and Sascha Stahl for having implemented and commissioned the revolutionary changes to the LHC Run-2 high-level-trigger, including the first widespread deployment of real-time analysis techniques in High Energy Physics;   Kevin Dungs and Tim Head for having launched the Starterkit initiative, a new style of software tutorials based on modern programming methods. “Starterkit is a group of ph...

  12. Chandra Early Type Galaxy Atals

    Science.gov (United States)

    Kim, Dong-Woo; Anderson, Craig; Burke, Douglas J.; Fabbiano, Giuseppina; Fruscione, Antonella; Lauer, Jennifer; McCollough, Michael; Morgan, Douglas; Mossman, Amy; O'Sullivan, Ewan; Paggi, Alessandro; Vrtilek, Saeqa Dil; Trinchieri, Ginevra

    2017-08-01

    The hot gas in early type galaxies (ETGs) plays a crucial role in understanding their formation and evolution. As the hot gas is often extended to the outskirts beyond the optical size, the large scale structural features identified by Chandra (including jets, cavities, cold fronts, filaments and tails) point to key evolutionary mechanisms, e.g., AGN feedback, merging history, accretion, stripping and star formation and its quenching. We have systematically analyzed the archival Chandra data of ~100 ETGs to study the hot ISM. We produce the uniformly derived data products with spatially resolved spectral information and will make them accessible via a public web site. With 2D spectral infomation, we further discuss gas morphology, scaling relations, X-ray based mass profiles and their implications related to various physical mechanisms (e.g., stellar and AGN feedback).

  13. Atypical manifestations of early syphilis

    Directory of Open Access Journals (Sweden)

    R V Koranne

    1990-01-01

    Full Text Available A study of 36 untreated patients with early syphilis revealed atypical variations namely; long incubation period of 101 days in I patient, more than 3 chancres in 1, undermined margin of the chancre along with tenderness in 1 and moderate to severe tenderness of the ulcers in 2 cases. In 3 patients there was no indurations of the ulcers. Three patients with primary syphilis had unilateral lymphadenitis, and in I case the lymph nodes were not only tender but showed tendency towardsmatingawell. Insecondarysyphilis, 11 out of 16 patients having condylomata lata had no other muco-cutaneous lesions. Concomitant presence of other venereal disease to account for the atypical manifestations was discounted- by appropriate laboratory tests, response to therapeutic agents and follow up.

  14. Women, motherhood and early childhood

    DEFF Research Database (Denmark)

    Ravnbøl, Camilla Ida

    This paper explores the question of how Roma women’s situation influences Roma children’s survival, growth and development in the early years. It focuses specifically on the barriers and opportunities for action that Roma women experience and how these influence their possibilities to engage...... in efforts for their young children. The paper adopts the perspective that in poor and socially excluded Roma communities, young children’s survival, growth and development cannot be addressed effectively if the rights of women are overlooked. Roma women navigate in contexts where they, as women, experience...... an assessment of the mothers’ capacity to internalize and act upon advice. It is argued that supporting Roma women’s access to human rights is likely to have positive outcomes for the women and their families, especially the young children...

  15. Physics of the early universe

    International Nuclear Information System (INIS)

    Brandenberger, R.H.

    1987-01-01

    When studying the evolution of the very early universe it is necessary to use a description of matter which is appropriate at very high energies, namely in terms of quantum fields. In such models there may be a period during which the ratio of pressure and energy density is - 1, an equation of state which leads to an exponential expansion of the universe (inflation). There may also arise stable topological defects similar to vortex lines in condensed matter physics. These defects (cosmic strings) form seeds about which gas can accrete to form galaxies and clusters of galaxies. The author reviews inflation and cosmic strings, emphasizing their role in generating the energy density perturbations which are required in order to explain the existence of structures in the universe

  16. Fossil Microorganisms in Archaean

    Science.gov (United States)

    Astafleva, Marina; Hoover, Richard; Rozanov, Alexei; Vrevskiy, A.

    2006-01-01

    Ancient Archean and Proterozoic rocks are the model objects for investigation of rocks comprising astromaterials. The first of Archean fossil microorganisms from Baltic shield have been reported at the last SPIE Conference in 2005. Since this confeence biomorphic structures have been revealed in Archean rocks of Karelia. It was determined that there are 3 types of such bion structures: 1. structures found in situ, in other words microorganisms even-aged with rock matrix, that is real Archean fossils biomorphic structures, that is to say forms inhabited early formed rocks, and 3. younger than Archean-Protherozoic minerali microorganisms, that is later contamination. We made attempt to differentiate these 3 types of findings and tried to understand of burial of microorganisms. The structures belongs (from our point of view) to the first type, or real Archean, forms were under examination. Practical investigation of ancient microorganisms from Green-Stone-Belt of Northern Karelia turns to be very perspective. It shows that even in such ancient time as Archean ancient diverse world existed. Moreover probably such relatively highly organized cyanobacteria and perhaps eukaryotic formes existed in Archean world.

  17. Acute leukemia in early childhood

    Directory of Open Access Journals (Sweden)

    M. Emerenciano

    2007-06-01

    Full Text Available Acute leukemia in early childhood is biologically and clinically distinct. The particular characteristics of this malignancy diagnosed during the first months of life have provided remarkable insights into the etiology of the disease. The pro-B, CD10 negative immunophenotype is typically found in infant acute leukemia, and the most common genetic alterations are the rearrangements of the MLL gene. In addition, the TEL/AML1 fusion gene is most frequently found in children older than 24 months. A molecular study on a Brazilian cohort (age range 0-23 months has detected TEL/AML1+ve (N = 9, E2A/PBX1+ve (N = 4, PML/RARA+ve (N = 4, and AML1/ETO+ve (N = 2 cases. Undoubtedly, the great majority of genetic events occurring in these patients arise prenatally. The environmental exposure to damaging agents that give rise to genetic changes prenatally may be accurately determined in infants since the window of exposure is limited and known. Several studies have shown maternal exposures that may give rise to leukemogenic changes. The Brazilian Collaborative Study Group of Infant Acute Leukemia has found that mothers exposed to dipyrone, pesticides and hormones had an increased chance to give birth to babies with infant acute leukemia [OR = 1.48 (95%CI = 1.05-2.07, OR = 2.27 (95%CI = 1.56-3.31 and OR = 9.08 (95%CI = 2.95-27.96], respectively. This review aims to summarize recent clues that have facilitated the elucidation of the biology of early childhood leukemias, with emphasis on infant acute leukemia in the Brazilian population.

  18. The early Earth atmosphere and early life catalysts.

    Science.gov (United States)

    Ramírez Jiménez, Sandra Ignacia

    2014-01-01

    Homochirality is a property of living systems on Earth. The time, the place, and the way in which it appeared are uncertain. In a prebiotic scenario two situations are of interest: either an initial small bias for handedness of some biomolecules arouse and progressed with life, or an initial slight excess led to the actual complete dominance of the known chiral molecules. A definitive answer can probably never be given, neither from the fields of physics and chemistry nor biology. Some arguments can be advanced to understand if homochirality is necessary for the initiation of a prebiotic homochiral polymer chemistry, if this homochirality is suggesting a unique origin of life, or if a chiral template such as a mineral surface is always required to result in an enantiomeric excess. A general description of the early Earth scenario will be presented in this chapter, followed by a general description of some clays, and their role as substrates to allow the concentration and amplification of some of the building blocks of life.

  19. EARLY POSTOPERATIVE COMPLICATIONS AFTER RADICAL CYSTECTOMY

    Directory of Open Access Journals (Sweden)

    V. O. Mager

    2014-08-01

    Full Text Available Radical cystectomy (RCE is associated with a considerable number of early postoperative complications as before. Based on 10 years’ experience, this paper demonstrates the frequency (33.9 % and types of early complications following RCE, as well as postoperative mortality (5.5 % and its resulting causes. Although postoperative mortality is relatively low today, the frequency of early postoperative complications remains high as before.

  20. Early rehabilitation and participation in focus

    DEFF Research Database (Denmark)

    Pallesen, Hanne; Buhl, Inge; Roenn-Smidt, Helle

    2016-01-01

    Early neurorehabilitation is an interdisciplinary field. Thus, in order to eliminate unnecessary barriers for individuals with severe acquired brain injury in early rehabilitation, we need rehabilitation science that supports both quantitative and qualitative research methods. Participation can...... be studied directly and indirectly. This commentary proposes that active participation and the ‘‘lived body’’ are essential terms in early rehabilitation of severe ABI patients, and a description of how these terms are interpreted and handled in the practice is needed....

  1. Genetics of Severe Early Onset Epilepsies

    Science.gov (United States)

    2017-08-24

    Epilepsy; Epileptic Encephalopathy; Ohtahara Syndrome; Infantile Spasms; Dravet Syndrome; Malignant Migrating Partial Epilepsy of Infancy; Early Myoclonic Epileptic Encephalopathy; PCDH19-related Epilepsy and Related Conditions

  2. Positioning and early mobilisation in stroke.

    Science.gov (United States)

    Keating, Moira; Penney, Maree; Russell, Petra; Bailey, Emma

    Stroke unit care, providing early rehabilitation, improves long-term outcomes for patients following a stroke. Early mobilisation and good positioning are recognised as key aspects of care in stroke units. Nurses working on stroke units have an important role because they are able to implement positioning and early mobilisation strategies 24 hours a day, reducing the risk of complications and improving functional recovery. Patients benefit if nurses work effectively with the therapy team in positioning and early mobilisation. Nurses also need appropriate training and expertise to make best use of specialist equipment.

  3. Scientific spirit in early childhood

    Directory of Open Access Journals (Sweden)

    Isabel Samacá Bohórquez

    2016-01-01

    Full Text Available Play and fun are key elements in the pedagogical work with five-year school children, since the teacher is required to carry out a hermeneutical and phenomenological exercise coming from the interaction among the different languages used by children to communicate their thoughts, emotions and ideas. In order to reflect about the scientific spirit in early childhood, it is necessary firstly to think about how its logic develops and operates and about the need to recognize in the sociocultural environment the possibilities to stimulate talents or the limitations demarcating their development, secondly, teaching practice must be thought in order to establish dialogue forums with students to know their needs and interests and guide their searches. To meet other is possible for children to the extent that the dialogical principle of knowledge interaction is recognized and the discovery of tensions and meeting points around the educational praxis, as an approach to infant’s rationality and his/her ways of learning, towards the social construction of boy and girl gender identity in our society.

  4. Early vision and focal attention

    Science.gov (United States)

    Julesz, Bela

    1991-07-01

    At the thirty-year anniversary of the introduction of the technique of computer-generated random-dot stereograms and random-dot cinematograms into psychology, the impact of the technique on brain research and on the study of artificial intelligence is reviewed. The main finding-that stereoscopic depth perception (stereopsis), motion perception, and preattentive texture discrimination are basically bottom-up processes, which occur without the help of the top-down processes of cognition and semantic memory-greatly simplifies the study of these processes of early vision and permits the linking of human perception with monkey neurophysiology. Particularly interesting are the unexpected findings that stereopsis (assumed to be local) is a global process, while texture discrimination (assumed to be a global process, governed by statistics) is local, based on some conspicuous local features (textons). It is shown that the top-down process of "shape (depth) from shading" does not affect stereopsis, and some of the models of machine vision are evaluated. The asymmetry effect of human texture discrimination is discussed, together with recent nonlinear spatial filter models and a novel extension of the texton theory that can cope with the asymmetry problem. This didactic review attempts to introduce the physicist to the field of psychobiology and its problems-including metascientific problems of brain research, problems of scientific creativity, the state of artificial intelligence research (including connectionist neural networks) aimed at modeling brain activity, and the fundamental role of focal attention in mental events.

  5. Early detection of materials degradation

    Science.gov (United States)

    Meyendorf, Norbert

    2017-02-01

    Lightweight components for transportation and aerospace applications are designed for an estimated lifecycle, taking expected mechanical and environmental loads into account. The main reason for catastrophic failure of components within the expected lifecycle are material inhomogeneities, like pores and inclusions as origin for fatigue cracks, that have not been detected by NDE. However, material degradation by designed or unexpected loading conditions or environmental impacts can accelerate the crack initiation or growth. Conventional NDE methods are usually able to detect cracks that are formed at the end of the degradation process, but methods for early detection of fatigue, creep, and corrosion are still a matter of research. For conventional materials ultrasonic, electromagnetic, or thermographic methods have been demonstrated as promising. Other approaches are focused to surface damage by using optical methods or characterization of the residual surface stresses that can significantly affect the creation of fatigue cracks. For conventional metallic materials, material models for nucleation and propagation of damage have been successfully applied for several years. Material microstructure/property relations are well established and the effect of loading conditions on the component life can be simulated. For advanced materials, for example carbon matrix composites or ceramic matrix composites, the processes of nucleation and propagation of damage is still not fully understood. For these materials NDE methods can not only be used for the periodic inspections, but can significantly contribute to the material scientific knowledge to understand and model the behavior of composite materials.

  6. Casebooks in Early Modern England:

    Science.gov (United States)

    Kassell, Lauren

    2014-01-01

    summary Casebooks are the richest sources that we have for encounters between early modern medical practitioners and their patients. This article compares astrological and medical records across two centuries, focused on England, and charts developments in the ways in which practitioners kept records and reflected on their practices. Astrologers had a long history of working from particular moments, stellar configurations, and events to general rules. These practices required systematic notation. Physicians increasingly modeled themselves on Hippocrates, recording details of cases as the basis for reasoned expositions of the histories of disease. Medical records, as other scholars have demonstrated, shaped the production of medical knowledge. Instead, this article focuses on the nature of casebooks as artifacts of the medical encounter. It establishes that casebooks were serial records of practice, akin to diaries, testimonials, and registers; identifies extant English casebooks and the practices that led to their production and preservation; and concludes that the processes of writing, ordering, and preserving medical records are as important for understanding the medical encounter as the records themselves. PMID:25557513

  7. Cosmology and the early universe

    Science.gov (United States)

    Joshi, Abhigna

    2017-01-01

    In the beginning the universe was in a hot dense state nearly 13.8 billion years ago. The thermal history of the universe was traced back to an era when the temperature was about 1012K. At this early time, the universe was filled with particles-mostly photons and leptons- whose interactions are hopefully weak enough to allow this medium to be treated as a more or less ideal gas. However, if we look back a little further, into the first 0.0001 second of cosmic history when the temperature was above 1012K. At such temperatures, there will be present in thermal equilibrium copious numbers of strongly interacting particles-mostly masons and baryons-with a mean interparticle distance less than a Compton wavelength. These particles will be in a state of continual mutual interaction, and cannot reasonably be expected to obey any simple equation of state. The inflationary epoch lasted from 10-36seconds after the Big Bang to sometime between 10-33and 10-32seconds. Matter and energy created in this time. Right after that space expanded exponentially with enormous rate of 74.3 +/-2.1Km per second per Mpc. Undergraduate student and researcher of the string theory, quantum gravity, cosmology and quantum biology.

  8. Cerebellar ataxia of early onset

    International Nuclear Information System (INIS)

    Yamashita, Sumimasa; Miyake, Shota; Yamada, Michiko; Iwamoto, Hiroko; Yamada, Kazuhiko.

    1989-01-01

    Eight cases of childhood cerebellar ataxia were reported. All these cases showed chronic cerebellar ataxia with early onset, and the other diseases of cerebellum such as infections, neoplasms and storage diseases were excluded by clinical symptoms and laboratory findings including blood counts, blood chemistry, lactate, pyruvate, ceruloplasmine, urinalysis, serum immunoglobulins, amino acid analysis in blood and urine, CSF analysis, leukocyte lysosomal enzymes, MCV, EMG, EEG and brain X-CT. Two pairs of siblings were included in this study. The clinical diagnosis were cerebellar type (5), spinocerebellar type (1), one Marinesco-Sjoegren syndrome and undetermined type (1). The age of onset was 1 to 5 years. The chief complaint was motor developmental delay in 6 cases; among them 5 patients could walk alone at the ages of 2 to 3 years'. Mental retardation was observed in 7 cases and epilepsy in 2. TRH was effective in 5 cases. The MRI study revealed that the area of medial sagittal slice of the cerebellum was reduced significantly in all cases and also that of pons was reduced in 5 cases. Different from typical adult onset spinocerebellar degenerations, most of the present cases have achieved slow developmental milestones and the clinical course was not progressive. Genetic factors are suspected in the pathogenesis of this disease in some cases. (author)

  9. Early Byzantine steelyard from Belgrade

    Directory of Open Access Journals (Sweden)

    Vujović Miroslav

    2014-01-01

    Full Text Available The initial aim of this paper was to present scholarly circles with a detailed report about the insufficiently known Early Byzantine steelyard beam (Figs. 2-5; Pl. I/1 treasured in Belgrade City Museum (further in the text BCM together with a small counterweight (Fig. 6; Pl. I/2 which, judging by its dimensions and weight, does not belong to it. However, after inspecting the documentation of BCM and the National Museum in Belgrade (further in the text NMB, the supposition that the steelyard beam from BCM represents a part of the same hoard with the well known counterweight (Fig. 7 in the form of a bust of a Byzantine empress, and the unpublished chain system with hooks for hanging loads (Fig. 8; Pl. IV, which are kept in NMB, was confirmed. The detailed examination of the museum inventory records shed light on the set of circumstances which led to the separation of the parts of the Belgrade steelyard. [Projekat Ministarstva nauke Republike Srbije, br. 177007: Romanizacija, urbanizacija i transformacija urbanih centara civilnog,vojnog i rezidencijalnog karaktera u rimskim provincijama na tlu Srbije

  10. On a chaotic early universe

    International Nuclear Information System (INIS)

    Tomita, Kenji.

    1974-11-01

    The theories regarding the origin of galaxies and elements are reviewed in this paper, and the assumptions made for these theories are discussed. It has been assumed that the universe has always been isotropic and homogeneous from the beginning of cosmic expansion. At the stage of very high density that any local irregularities such as galaxies cannot exist, the admissible deviation in this case from the mean value is only the statistical or quantum fluctuation of matter density, spatial curvature or their growth. It should be considered that the chemical composition of matters at the earliest stage consisted of most fundamental particles. However, if the fluctuation of matter density is statistical, the present values are too small. As for the origin of elements, it depends strongly on the period when cosmic radiation appeared. The final mass ratios of elements are given from the present baryon mass density, and are in agreement with observed values. The assumption of hot universe seems good. However, the time-independent ratio of photon number to baryon number is hardly understood. It is reasonable to assume for the early universe an inhomogeneous model whose space-time curvature is of turbulent character, according to weak cosmological principle. The inhomogeneous models to be considered are weakly non-linear perturbation theory, anti-Newtonian approximation and post anti-Newtonian approximation. Smoothing-out process, the origin of cosmic microwave radiation, the origin of galaxies and the origin of chemical elements are discussed. (Kato, T.)

  11. Multiplicity in Early Stellar Evolution

    Science.gov (United States)

    Reipurth, B.; Clarke, C. J.; Boss, A. P.; Goodwin, S. P.; Rodríguez, L. F.; Stassun, K. G.; Tokovinin, A.; Zinnecker, H.

    Observations from optical to centimeter wavelengths have demonstrated that multiple systems of two or more bodies is the norm at all stellar evolutionary stages. Multiple systems are widely agreed to result from the collapse and fragmentation of cloud cores, despite the inhibiting influence of magnetic fields. Surveys of class 0 protostars with millimeter interferometers have revealed a very high multiplicity frequency of about 2/3, even though there are observational difficulties in resolving close protobinaries, thus supporting the possibility that all stars could be born in multiple systems. Near-infrared adaptive optics observations of class I protostars show a lower binary frequency relative to the class 0 phase, a declining trend that continues through the class II/III stages to the field population. This loss of companions is a natural consequence of dynamical interplay in small multiple systems, leading to ejection of members. We discuss observational consequences of this dynamical evolution, and its influence on circumstellar disks, and we review the evolution of circumbinary disks and their role in defining binary mass ratios. Special attention is paid to eclipsing PMS binaries, which allow for observational tests of evolutionary models of early stellar evolution. Many stars are born in clusters and small groups, and we discuss how interactions in dense stellar environments can significantly alter the distribution of binary separations through dissolution of wider binaries. The binaries and multiples we find in the field are the survivors of these internal and external destructive processes, and we provide a detailed overview of the multiplicity statistics of the field, which form a boundary condition for all models of binary evolution. Finally, we discuss various formation mechanisms for massive binaries, and the properties of massive trapezia.

  12. Near Heterophoria in Early Childhood

    Science.gov (United States)

    Babinsky, Erin; Sreenivasan, Vidhyapriya; Candy, T. Rowan

    2015-01-01

    Purpose. The purpose of this study was to measure near heterophoria in young children to determine the impact of early growth and development on the alignment of the eyes. Methods. Fifty young children (≥2 and accommodation responses, in the absence of optical correction, were measured using simultaneous Purkinje image tracking and photorefraction technology (MCS PowerRefractor, PR). The resulting heterophorias, and both accommodative convergence/accommodation (AC/A) and convergence accommodation/convergence (CA/C) ratios were then computed as a function of age, refractive error, and an alternating cover test. Results. The mean heterophoria after approximately 60 seconds of dissociation at a 33-cm viewing distance was 5.0 prism diopters (pd) of exophoria (SD ± 3.7) in the children (78% of children > 2 pd exophoric) and 5.6 pd of exophoria (SD ± 4.7) in adults (69% of adults > 2pd exophoric; a nonsignificant difference), with no effect of age between 2 and 6 years. In these children, heterophoria was not significantly correlated with AC/A (r = 0.25), CA/C (r = 0.12), or refractive error (r = 0.21). The mean difference between heterophoria measurements from the PR and the clinical cover test was −2.4 pd (SD = ±3.4), with an exophoric bias in the PR measurements. Conclusions. Despite developmental maturation of interpupillary distance, refractive error, and AC/A, in a typical sample of young children the predominant dissociated position is one of exophoria. PMID:25634983

  13. From early wireless to Everest.

    Science.gov (United States)

    Allen, A

    1998-01-01

    Medical information has been transmitted using wireless technologies for almost 80 years. A "wired wireless" electronic stethoscope was developed by the U.S. Army Signal Corps in the early 1920's, for potential use in ship-to-shore transmission of cardiac sounds. [Winters SR. Diagnosis by wireless. Scientific American June 11, 1921, p. 465] Today, wireless is used in a wide range of medical applications and at sites from transoceanic air flights to offshore oil platforms to Mt. Everest. 'Wireless LANs' are often used in medical environments. Typically, nurses and physicians in a hospital or clinic use hand-held "wireless thin client" pen computers that exchange patient information and images with the hospital server. Numerous companies, such as Fujitsu (article below) and Cruise Technologies (www.cruisetech.com) manufacture handheld pen-entry computers. One company, LXE, integrates radio-frequency (RF) enhanced hand-held computers specifically designed for production use within a wireless LAN (www.lxe.com). Other companies (Proxim, Symbol, and others) supply the wireless RF LAN infrastructure for the enterprise. Unfortunately, there have been problems with widespread deployment of wireless LANs. Perhaps the biggest impediment has been the lack of standards. Although an international standard (IEEE 802.11) was adopted in 1997, most wireless LAN products still are not compatible with the equipment of competing companies. A problem with the current standard for LAN adapters is that throughput is limited to 3 Mbps--compared to at least 10 Mbps, and often 100 Mbps, in a hard-wired Ethernet LAN. An II Mbps standard is due out in the next year or so, but it will be at least 2 years before standards-compliant products are available. This story profiles some of the ways that wireless is being used to overcome gaps in terrestrial and within-enterprise communication.

  14. REVIEW ARTICLE Conjugated Hyperbilirubinaemia in Early Infancy ...

    African Journals Online (AJOL)

    REVIEW ARTICLE Conjugated Hyperbilirubinaemia in Early Infancy. AOK Johnson. Abstract. Conjugated hyperbilirubinaemia exists when the conjugated serum bilirubin level is more than 2 mg/dl or more than 20 per cent of the total serum bilirubin. It is always pathological in early infancy. The causes are many and diverse ...

  15. Early detection of COPD in general practice

    DEFF Research Database (Denmark)

    Dahl, Ronald; Ulrik, Charlotte Suppli; Løkke, Anders

    2011-01-01

    Early detection enables the possibility for interventions to reduce the future burden of COPD. The Danish National Board of Health recommends that individuals >35 years with tobacco/occupational exposure, and at least 1 respiratory symptom should be offered a spirometry to facilitate early detect...

  16. Problem Solving in the Early Years

    Science.gov (United States)

    Diamond, Lindsay Lile

    2018-01-01

    Problem solving is recognized as a critical component to becoming a self-determined individual. The development of this skill should be fostered in the early years through the use of age-appropriate direct and embedded activities. However, many early childhood teachers may not be providing adequate instruction in this area. This column provides a…

  17. Early Adolescent Sexual Activity: A Developmental Study.

    Science.gov (United States)

    Whitbeck, Les B.; Yoder, Kevin A.; Hoyt, Dan R.; Conger, Rand D.

    1999-01-01

    Examines predictors of early sexual intercourse for a sample of 457 adolescents in grades 8 through 10, from two-parent and single-mother families. Significant decreases were noted in the effect of mother monitoring by 10th grade. The primary predictors of early intercourse were age, opportunity (steady relationship), sexually permissive attitude,…

  18. Early Stuttering, Temperament and Anxiety: Two Hypotheses

    Science.gov (United States)

    Kefalianos, Elaina; Onslow, Mark; Block, Susan; Menzies, Ross; Reilly, Sheena

    2012-01-01

    Purpose: The topic of temperament and early stuttering and the extent to which it involves anxiety is theoretically and clinically relevant. The topic can contribute to theory development and clinical practices with early stuttering. Method: We present a review of the empirical literature for this area with a view to determining which of two…

  19. 37 CFR 1.219 - Early publication.

    Science.gov (United States)

    2010-07-01

    ... 37 Patents, Trademarks, and Copyrights 1 2010-07-01 2010-07-01 false Early publication. 1.219... COMMERCE GENERAL RULES OF PRACTICE IN PATENT CASES National Processing Provisions Publication of Applications § 1.219 Early publication. Applications that will be published under § 1.211 may be published...

  20. Early Parental Depression and Child Language Development

    Science.gov (United States)

    Paulson, James F.; Keefe, Heather A.; Leiferman, Jenn A.

    2009-01-01

    Objective: To examine the effects of early maternal and paternal depression on child expressive language at age 24 months and the role that parent-to-child reading may play in this pathway. Participants and methods: The 9-month and 24-month waves from a national prospective study of children and their families, the Early Childhood Longitudinal…

  1. The transcriptome landscape of early maize meiosis

    Science.gov (United States)

    Meiosis, particularly meiotic recombination, is a major factor affecting yield and breeding of plants. To gain insight into the transcriptome landscape during early initiation steps of meiotic recombination, we profiled early prophase I meiocytes from maize using RNA-seq. Our analyses of genes prefe...

  2. Early Care in Children with Neurodevelopmental Disorders

    Science.gov (United States)

    Ponce-Meza, Jacqueline

    2017-01-01

    The article analyzes the importance of early care in child development, guiding a neuropsychological perspective of development. The early care model seeks to refer to the set of interventions aimed at children and their work in conjunction with a multidisciplinary team. It presents recommendations for the implementation of programs that allow…

  3. Gender and Boys' Singing in Early Childhood

    Science.gov (United States)

    Hall, Clare

    2005-01-01

    This article derives from a research project investigating the singing behaviour of a group of Australian boys in their first year of school. The project showed that the genesis of the "missing male" trend in singing at school may be occurring in early childhood. The impact of hegemonic masculinity in early childhood is explored here by…

  4. Pretend Play in the Early Childhood Classroom

    Science.gov (United States)

    McEntire, Nancy

    2009-01-01

    This article presents and summarizes recent resources related to pretend play in the early childhood classroom. These include "Contemporary Perspectives on Play in Early Childhood Education" by Olivia N. Sarachoe and Bernard Spodek; "Dramatic Play: Bring It Back" by Tammy Benson; and "The Importance of Being Playful" by Elena Bodrova and Deborah…

  5. Transforming early childhood education for sustainable development

    African Journals Online (AJOL)

    This paper examined the ways in which early childhood education needs to be transformed for sustainable development. These ways include teaching children environmental security through play, personal hygiene, appropriate waste use and disposal, and nature awareness. It was recommended that early childhood ...

  6. Early detection of ecosystem regime shifts

    DEFF Research Database (Denmark)

    Lindegren, Martin; Dakos, Vasilis; Groeger, Joachim P.

    2012-01-01

    methods may have limited utility in ecosystem-based management as they show no or weak potential for early-warning. We therefore propose a multiple method approach for early detection of ecosystem regime shifts in monitoring data that may be useful in informing timely management actions in the face...

  7. Legitimacy and the Value of Early Customers

    NARCIS (Netherlands)

    Wang, Tang; Song, Michael; Zhao, Y. Lisa

    2014-01-01

    To overcome resource constraints and achieve exponential growth, a new venture must rely on early customers of its products to communicate value and commitment to others. For this reason, founders of new ventures focus more on early customers as a key element of their founding strategy than on other

  8. Early-stage mantle cell lymphoma

    DEFF Research Database (Denmark)

    Dabaja, B S; Zelenetz, A D; Ng, A K

    2017-01-01

    Background: Mantle cell lymphoma (MCL) rarely presents as early-stage disease, but clinical observations suggest that patients who present with early-stage disease may have better outcomes than those with advanced-stage disease. Patients and methods: In this 13-institution study, we examined...

  9. Early Childhood Math: Make It Manipulative!

    Science.gov (United States)

    Stone, Janet I.

    1987-01-01

    Maintains that early childhood teachers should provide young children with creative, stimulating, and manipulative (hands-on) experiences rather than workbook pages in early mathematics programs. Presents reasons and corresponding counterpositions for using workbooks and suggests sample activities which teachers can use to make mathematics more…

  10. Early Years Students' Relationships with Mathematics

    Science.gov (United States)

    Takeuchi, Miwa Aoki; Towers, Jo; Plosz, Jennifer

    2016-01-01

    Early years mathematics experiences have been shown to be a significant predictor for students' school readiness and future mathematics achievement. Previous research also indicates an important connection between emotion and mathematics learning. How do students in early years education in Alberta describe their emotional relationship with…

  11. New treatment of early fetal chylothorax

    DEFF Research Database (Denmark)

    Nygaard, Ulrikka; Sundberg, Karin; Nielsen, Henriette Svarre

    2007-01-01

    OBJECTIVE: To evaluate OK-432, a preparation of Streptococcus pyogenes, in the treatment of early fetal chylothorax. METHODS: A prospective study of all fetuses (n=7) with persistent early chylothorax (gestational ages 16-21 weeks) referred to the tertiary center of fetal medicine in Denmark in 2...

  12. Radical surgery for early stage cervical cancer

    NARCIS (Netherlands)

    Derks, M.

    2017-01-01

    Cervical cancer is one of the most common malignancies in women worldwide. Due to an effective screening programme, in the Netherlands cervical cancer is often detected in early stages of disease. For early stage (International Federation of Gynaecology and Obstetrics (FIGO) stage IB/IIA) cervical

  13. Early adolescent music preferences and minor delinquency

    NARCIS (Netherlands)

    ter Bogt, T.F.M.; Keijsers, L.G.M.T.; Meeus, W.H.J.

    2013-01-01

    Objectives: To test Music Marker Theory (MMT) positing that early adolescents’ preferences for nonmainstream types of popular music indicate concurrent and later minor delinquency. Methods: MMT was tested in a 4-year longitudinal study (n = 309). Results: The results showed that early fans of

  14. The EHDI and Early Intervention Connection

    Science.gov (United States)

    Nelson, Lauri; Bradham, Tamala S.; Houston, K. Todd

    2011-01-01

    State coordinators of early hearing detection and intervention (EHDI) programs completed a strengths, weaknesses, opportunities, and threats, or SWOT, analysis that examined 12 areas within state EHDI programs. For the early intervention focus question, 48 coordinators listed 273 items, and themes were identified within each SWOT category. A…

  15. Challenges and limitations in early intervention

    NARCIS (Netherlands)

    Hadders-Algra, Mijna

    Research over the past three decades has shown that early intervention in infants biologically at risk of developmental disorders, irrespective of the presence of a brain lesion, is associated with improved cognitive development in early childhood without affecting motor development. However, at

  16. Early Childhood Education: History, Theory, and Practice

    Science.gov (United States)

    Morgan, Harry

    2006-01-01

    In this book, the author covers the history, theory, and practices that influence early childhood education along with an emphasis on infant and toddler care and education. He also presents a comparison of the conflict between education planners who support early childhood studies and state school systems whose cost-saving measures are dismantling…

  17. Transforming the Early Care and Education Workforce

    Science.gov (United States)

    Vecchiotti, Sara

    2018-01-01

    There is ample opportunity for state boards to improve outcomes for children by strengthening the early care and education workforce and thereby improving the quality of early care and education. Ensuring that ECE professionals have the knowledge, supports, and resources they need to support children's learning is one avenue to improving the…

  18. Early Sport Specialization: A Psychological Perspective

    Science.gov (United States)

    Gould, Daniel

    2010-01-01

    Specializing too early in life can lead to emotional stress, loss of motivation, and burnout, but the research is inadequate to resolve the question of whether early specialization or diversification is more beneficial from a psychological perspective. Nevertheless, some best practices are recommended based on the known benefits and detriments.…

  19. Gene expression in early stage cervical cancer

    NARCIS (Netherlands)

    Biewenga, Petra; Buist, Marrije R.; Moerland, Perry D.; van Thernaat, Emiel Ver Loren; van Kampen, Antoine H. C.; ten Kate, Fiebo J. W.; Baas, Frank

    2008-01-01

    Objective. Pelvic lymph node metastases are the main prognostic factor for survival in early stage cervical cancer, yet accurate detection methods before surgery are lacking. In this study, we examined whether gene expression profiling can predict the presence of lymph node metastasis in early stage

  20. Understanding the Early Years (UEY) Initiative

    Science.gov (United States)

    Human Resources and Social Development Canada, 2007

    2007-01-01

    Internal Audit Services conducted an Early Implementation Review of the Understanding the Early Years (UEY) Initiative in 2006-07. This review is intended to provide assurance to senior management that program delivery has been established appropriately in order to meet its objectives and highlight any areas that require focused management…

  1. Early dissemination seeds metastasis in breast cancer

    Science.gov (United States)

    Hosseini, Hedayatollah; Obradović, Milan M.S.; Hoffmann, Martin; Harper, Kathryn; Sosa, Maria Soledad; Werner-Klein, Melanie; Nanduri, Lahiri Kanth; Werno, Christian; Ehrl, Carolin; Maneck, Matthias; Patwary, Nina; Haunschild, Gundula; Gužvić, Miodrag; Reimelt, Christian; Grauvogl, Michael; Eichner, Norbert; Weber, Florian; Hartkopf, Andreas; Taran, Florin-Andrei; Brucker, Sara Y.; Fehm, Tanja; Rack, Brigitte; Buchholz, Stefan; Spang, Rainer; Meister, Gunter; Aguirre-Ghiso, Julio A.; Klein, Christoph A.

    2016-01-01

    Accumulating data suggest that metastatic dissemination often occurs early during tumour formation but the mechanisms of early metastatic spread have not yet been addressed. Here, we studied metastasis in a HER2-driven mouse breast cancer model and found that progesterone-induced signalling triggered migration of cancer cells from early lesions shortly after HER2 activation, but promoted proliferation in advanced primary tumour cells. The switch from migration to proliferation was regulated by elevated HER2 expression and increased tumour cell density involving miRNA-mediated progesterone receptor (PGR) down-regulation and was reversible. Cells from early, low-density lesions displayed more stemness features than cells from dense, advanced tumours, migrated more and founded more metastases. Strikingly, we found that at least 80% of metastases were derived from early disseminated cancer cells (DCC). Karyotypic and phenotypic analysis of human disseminated cancer cells and primary tumours corroborated the relevance of these findings for human metastatic dissemination. PMID:27974799

  2. Validation of the Early Functional Abilities scale

    DEFF Research Database (Denmark)

    Poulsen, Ingrid; Kreiner, Svend; Engberg, Aase W

    2018-01-01

    model item analysis. A secondary objective was to examine the relationship between the Early Functional Abilities scale and the Functional Independence Measurement™, in order to establish the criterion validity of the Early Functional Abilities scale and to compare the sensitivity of measurements using......), facio-oral, sensorimotor and communicative/cognitive functions. Removal of one item from the sensorimotor scale confirmed unidimensionality for each of the 4 subscales, but not for the entire scale. The Early Functional Abilities subscales are sensitive to differences between patients in ranges in which......OBJECTIVE: The Early Functional Abilities scale assesses the restoration of brain function after brain injury, based on 4 dimensions. The primary objective of this study was to evaluate the validity, objectivity, reliability and measurement precision of the Early Functional Abilities scale by Rasch...

  3. Bolatu's pharmacy theriac in early modern China.

    Science.gov (United States)

    Nappi, Carla

    2009-01-01

    In early modem China, natural history and medicine were shifting along with the boundaries of the empire. Naturalists struggled to cope with a pharmacy's worth of new and unfamiliar substances, texts, and terms, as plants, animals, and the drugs made from them travelled into China across land and sea. One crucial aspect of this phenomenon was the early modern exchange between Islamic and Chinese medicine. The history of theriac illustrates the importance of the recipe for the naturalization of foreign objects in early modem Chinese medicine. Theriac was a widely sought-after and hotly debated product in early modern European pharmacology and arrived into the Chinese medical canon via Arabic and Persian texts. The dialogue between language and material objects was critical to the Silk Road drug trade, and transliteration was ultimately a crucial technology used to translate drugs and texts about them in the early modern world.

  4. Screening of colorectal early cancer by radiology

    International Nuclear Information System (INIS)

    Matsukawa, M.; Usui, Y.; Kobayashi, S.

    1988-01-01

    The incidence of colorectal cancer has been gradually increasing in Japan, and if the present rate of increase is maintained it has been estimated that it will become the most common of all malignant neoplasms by the year 2000. It has been proved that colorectal cancer can be completely cured, if it is treated in its early phase. Early cancer of the large bowel is defined as a cancer which is limited to the mucosal membrane or submucosal layer, regardless of lymph node and distant metastases. Detection of early cancer improves the overall curability of colorectal cancer. The greatest number of early cancers of the large bowel are polypoid lesions in their macroscopic form, and depressed lesions are rarely encountered. Accordingly, the first step in the detection of early cancer starts with the screening of polypoid lesion by radiology and endoscopy. This paper is concerned with diagnostic accuracy of radiology in the screening of colorectal cancer with endoscopic correlation

  5. Sophisticated digestive systems in early arthropods.

    Science.gov (United States)

    Vannier, Jean; Liu, Jianni; Lerosey-Aubril, Rudy; Vinther, Jakob; Daley, Allison C

    2014-05-02

    Understanding the way in which animals diversified and radiated during their early evolutionary history remains one of the most captivating of scientific challenges. Integral to this is the 'Cambrian explosion', which records the rapid emergence of most animal phyla, and for which the triggering and accelerating factors, whether environmental or biological, are still unclear. Here we describe exceptionally well-preserved complex digestive organs in early arthropods from the early Cambrian of China and Greenland with functional similarities to certain modern crustaceans and trace these structures through the early evolutionary lineage of fossil arthropods. These digestive structures are assumed to have allowed for more efficient digestion and metabolism, promoting carnivory and macrophagy in early arthropods via predation or scavenging. This key innovation may have been of critical importance in the radiation and ecological success of Arthropoda, which has been the most diverse and abundant invertebrate phylum since the Cambrian.

  6. Long-term Consequences of Early Parenthood

    DEFF Research Database (Denmark)

    Johansen, Eva Rye; Nielsen, Helena Skyt; Verner, Mette

    (and to lesser extent employment), as fathers appear to support the family, especially when early parenthood is combined with cohabitation with the mother and the child. Heterogeneous effects reveal that individuals with a more favorable socioeconomic background are affected more severely than......Having children at an early age is known to be associated with unfavorable economic outcomes, such as lower education, employment and earnings. In this paper, we study the long-term consequences of early parenthood for mothers and fathers. Our study is based on rich register-based data that......, importantly, merges all childbirths to the children’s mothers and fathers, allowing us to study the consequences of early parenthood for both parents. We perform a sibling fixed effects analysis in order to account for unobserved family attributes that are possibly correlated with early parenthood...

  7. Diastolic and autonomic dysfunction in early cirrhosis

    DEFF Research Database (Denmark)

    Dahl, Emilie Kristine; Møller, Søren; Kjær, Andreas

    2014-01-01

    OBJECTIVE. Presence of cardiac dysfunction in patients with advanced cirrhosis is widely accepted, but data in early stages of cirrhosis are limited. Systolic and diastolic functions, dynamics of QT-interval, and pro-atrial natriuretic peptide (pro-ANP) are investigated in patients with early stage...... cirrhosis during maximal β-adrenergic drive. MATERIAL AND METHODS. Nineteen patients with Child A (n = 12) and Child B cirrhosis (n = 7) and seven matched controls were studied during cardiac stress induced by increasing dosages of dobutamine and atropine. RESULTS. Pharmacological responsiveness was similar...... indicate that patients with early stage cirrhosis exhibit early diastolic and autonomic dysfunction as well as elevated pro-ANP. However, the cardiac chronotropic and inotropic responses to dobutamine stress were normal. The dynamics of ventricular repolarization appears normal in patients with early stage...

  8. The Association between Early Conduct Problems and Early Marijuana Use in College Students

    Science.gov (United States)

    Falls, Benjamin J.; Wish, Eric D.; Garnier, Laura M.; Caldeira, Kimberly M.; O'Grady, Kevin E.; Vincent, Kathryn B.; Arria, Amelia M.

    2011-01-01

    Early conduct problems have been linked to early marijuana use in adolescence. The present study examines this association in a sample of 1,076 college students that was divided into three groups: (1) early marijuana users (began marijuana use prior to age 15; N = 126), (2) late marijuana users (began marijuana use at or after age 15; N = 607),…

  9. Early Childhood Educators' Perceived and Actual Metalinguistic Knowledge, Beliefs and Enacted Practice about Teaching Early Reading

    Science.gov (United States)

    Hammond, Lorraine

    2015-01-01

    Results of influential reports on early literacy have drawn attention to the need for early childhood educators to take up a more explicit, teacher-directed approach to beginning reading. Positive classroom results however are in part dependent upon teacher knowledge and this study investigated the relationship between early childhood educators'…

  10. Early onset depression: the relevance of anxiety.

    Science.gov (United States)

    Parker, G; Wilhelm, K; Asghari, A

    1997-01-01

    The aim of this study was to determine risk factors that may differentiate early onset from late onset depression. A non-clinical cohort that had been assessed from 1978 to 1993 at 5 yearly intervals and that had a high prevalence rate of lifetime depression took part in the study. We established an appropriate age cut-off to distinguish early onset (i.e. before 26 years) of major and of minor depression, and examined the relevance of a number of possible determinants of early onset depression assessed over the life of the study. Despite several dimensional measures of depression, self-esteem and personality being considered, they generally failed (when assessed early in the study) to discriminate subsequent early onset depression, with the exception of low masculinity scores being a weak predictor of major and/or minor depression. Early onset depression was strongly predicted, however, by a lifetime episode of a major anxiety disorder, with generalised anxiety being a somewhat stronger and more consistent predictor than panic disorder, agoraphobia and minor anxiety disorders (ie social phobia, simple phobia). The possibility that anxiety may act as a key predispositional factor to early onset depression and to a greater number of depressive episodes is important in that clinical assessment and treatment of any existing anxiety disorder may be a more efficient and useful strategy than focussing primarily on the depressive disorder.

  11. [Treatment of early stage Hodgkin disease

    DEFF Research Database (Denmark)

    Specht, Lena; Carde, P.; Mauch, P.

    1993-01-01

    indicate that we still do not definitively know whether or not the early addition of prophylactic chemotherapy improves survival. Arguments in favour of early chemotherapy are: that laparotomy may be avoided, that radiation fields and doses may perhaps be reduced, and that the stress of experiencing...... a relapse is avoided in many patients. The major argument against early chemotherapy is: that by careful staging and selection of patients and by careful radiotherapy techniques the number of patients exposed to potentially toxic chemotherapy may be kept at a minimum. Recently, trials have been carried out...

  12. The determinants of early retirement in Switzerland

    OpenAIRE

    Dorn, David; Sousa-Poza, Alfonso

    2005-01-01

    In the past decade, Switzerland has experienced a large increase in the number of individuals going into early retirement. This paper examines the determinants of such early retirement using data from the newly implemented social-security module of the 2002 Swiss Labor Force Survey. In the sixteen-month period from January 2001 to April 2002, more than 36,000 older individuals, representing 8% of all workers within nine years of legal retirement age, became early retirees. One of the most imp...

  13. Diagnosis of early stomach cancer (Lecture)

    International Nuclear Information System (INIS)

    Vinner, M.G.

    1989-01-01

    Problems concerning diagnosis of early stomach cancer using X-ray and endoscopic investigation techniques are stated. Classification of early stomach cancer suggested by the Japan Endoscopy Society and division system of early stomach cancer into two main foms: depth (erosive-ulcerous) one and elevated (polypoid) one-is presented X-ray and endoscopic investigation techniques are shown to be high efficiency concerning revealingation of stomach mucous variations using biopsy, which allow to determine for certain whother the process is benign or malignant one

  14. A major 2.1 Ga event of mafic magmatism in west Africa: An Early stage of crustal accretion

    Science.gov (United States)

    Abouchami, Wafa; Boher, Muriel; Michard, Annie; Albarede, Francis

    1990-10-01

    environments. Back-arc or low-Ti continental flood basalts provide a marginally good agreement but still face some difficulties. Oceanic flood basalts similar to those which form oceanic plateaus (e.g. in the Nauru basin) and later accreted to continents as allochtonous terranes represent the most acceptable modern analogue of many Proterozoic basalts. It is suggested that deep plumes piercing young lithosphere can generate huge amounts of tholeiites in a short time. Birimian basalts, like many Early Proterozoic basalts, may also be viewed as recent equivalents of the Archean greenstone belts. The modern komatiite of Gorgona Island is suggested to fit this model of intraplate volcanism. Although the 2.1 Ga magmatic event in West Africa has gone virtually unnoticed in the literature, it extends over several thousand kilometers and compares with the distribution of mantle-derived magmatic activity in other major orogenic provinces (e.g. Superior). It shows that the growth rate of continents cannot be extrapolated from the data obtained solely from the best studied continents (North America, Europe, Australia). If such large crustal segments were overlooked, a spurious pattern of episodic activity of the mantle could arise.

  15. Selective phosphorylation during early macrophage differentiation

    KAUST Repository

    Zhang, Huoming; Qian, Pei-Yuan; Ravasi, Timothy

    2015-01-01

    -regulated phosphoproteins in the early stages of differentiation. Further analysis of the PMA-regulated phosphoproteins revealed that transcriptional suppression, cytoskeletal reorganization and cell adhesion were among the most significantly activated pathways. Some key

  16. Subcortical functional reorganization due to early blindness.

    Science.gov (United States)

    Coullon, Gaelle S L; Jiang, Fang; Fine, Ione; Watkins, Kate E; Bridge, Holly

    2015-04-01

    Lack of visual input early in life results in occipital cortical responses to auditory and tactile stimuli. However, it remains unclear whether cross-modal plasticity also occurs in subcortical pathways. With the use of functional magnetic resonance imaging, auditory responses were compared across individuals with congenital anophthalmia (absence of eyes), those with early onset (in the first few years of life) blindness, and normally sighted individuals. We find that the superior colliculus, a "visual" subcortical structure, is recruited by the auditory system in congenital and early onset blindness. Additionally, auditory subcortical responses to monaural stimuli were altered as a result of blindness. Specifically, responses in the auditory thalamus were equally strong to contralateral and ipsilateral stimulation in both groups of blind subjects, whereas sighted controls showed stronger responses to contralateral stimulation. These findings suggest that early blindness results in substantial reorganization of subcortical auditory responses. Copyright © 2015 the American Physiological Society.

  17. Early ontogeny of Labeo capensis (pisces: Cyprinidae)

    African Journals Online (AJOL)

    the early development of Indian Labeo species (e.g. Khan. 1925; Ahmad 1944 ...... ber, size or intensity, was helpful in grouping North American cyprinid larvae. .... impregnated eggs of common freshwater fishes of Bengal. Curro Sci. 26: 125 ...

  18. PREVALENCE OF EARLY WARNINNG SIGNS AND SYMPTOMS ...

    African Journals Online (AJOL)

    FOBUR

    Mental illness is a psychological, emotional and mental health problems that affects .... review of the field of child psychiatric epidemiology ... occurs at early adolescent and mood disorders tend .... types of hospitals, and primary health clinics.

  19. Diagnosis and early management of acute hyperammonaemia

    Directory of Open Access Journals (Sweden)

    Mojca Žerjav Tanšek

    2010-02-01

    Elevated ammonia concentration is neurotoxic and causes irreversible glial and neuronal damage resulting in cerebral oedema with poor outcome. Early diagnosis and prompt treatment are crucial and may considerably improve the clinical course.

  20. Genetics Home Reference: early-onset glaucoma

    Science.gov (United States)

    ... called a syndrome. If glaucoma appears before the age of 5 without other associated abnormalities, it is called primary congenital glaucoma. Other individuals experience early onset of primary open-angle glaucoma, the most ...

  1. Colorectal Cancer: The Importance of Early Detection

    Science.gov (United States)

    ... of this page please turn JavaScript on. Feature: Colorectal Cancer The Importance of Early Detection Past Issues / Summer ... Cancer of the colon or rectum is called colorectal cancer. The colon and the rectum are part of ...

  2. Early Education for Asian American Children.

    Science.gov (United States)

    Kitano, Margie K.

    1980-01-01

    A review of early education for Asian American children (Japanese, Chinese, Filipinos, Vietnamese, Koreans, Hawaiians, and Samoans) focuses on the 1975 Asian American Education Project, a study of the learning characteristics of preschool age children and its educational implications. (CM)

  3. Exploring Equity in Early Postsecondary Education

    Science.gov (United States)

    Fox, Heather L.; Zamani-Gallaher, Eboni M.

    2018-01-01

    This chapter examines how postsecondary practitioners are encouraged to work collaboratively with child welfare agencies and other community-based organizations to identify and implement culturally responsive supports for former foster youth to promote early academic achievement.

  4. Early and Periodic Screening, Diagnosis and Treatment

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Early and Periodic Screening, Diagnostic and Treatment (EPSDT) benefit provides comprehensive and preventive health care services for children under age 21 who...

  5. EARLY CHILDHOOD CARE & EDUCATION: AN ICT PERSPECTIVE

    Directory of Open Access Journals (Sweden)

    Pradeep Kumar Mishra

    2012-03-01

    Full Text Available In the 21st century, technology serves to reinforce the educational bedrock of any country. Technology has revolutionized the teaching learning process by integrating different source of knowledge - clearly visible from primary to post-tertiary level. This paper examines the introduction of ICT in early childhood years centred on the relationship of ICT with the cognitive, emotional and social development of children. The paper discusses various aspects of the ongoing debate around ICT usage in the early years and tries to answer some of the relevant issues namely, the rationale for early introduction of ICT, the perceived risks and benefits involved in its usage, the role of the parents, and fostering appropriate application of ICT in the early childhood classrooms.

  6. Business Case for Early Childhood Investments

    Science.gov (United States)

    America's Promise Alliance (NJ1), 2011

    2011-01-01

    America's Promise's ReadyNation initiative has released this brief, which "makes the case" to business leaders on why investing in early childhood should be important to them. The brief includes "how-to" tips, helpful statistics and more.

  7. Early- versus Late-Onset Dysthymia

    Science.gov (United States)

    Sansone, Lori A.

    2009-01-01

    In the current Diagnostic and Statistical Manual of Mental Disorders, dysthymic disorder is categorized as either early-onset or late-onset, based upon the emergence of symptoms before or after the age of 21, respectively. Does this diagnostic distinction have any meaningful clinical implications? In this edition of The Interface, we present empirical studies that have, within a single study, compared individuals with early-versus late-onset dysthymia. In this review, we found that, compared to those with late-onset dysthymia, early-onset patients are more likely to harbor psychiatric comorbidity both on Axis I and II, exhibit less psychological resilience, and have more prominent family loadings for mood disorders. These findings suggest that this distinction is meaningful and that the early-onset subtype of dysthymia is more difficult to effectively treat. PMID:20049145

  8. Early Childhood Physical Education. The Essential Elements.

    Science.gov (United States)

    Gabbard, Carl

    1988-01-01

    Details are presented regarding the essential elements of an effective early childhood physical education curriculum. Components include movement awareness, fundamental locomotor skills, fundamental nonlocomotor skills, fundamental manipulative skills, and health-related fitness. (CB)

  9. Early medieval touchstones from Sowinki, Greater Poland

    Czech Academy of Sciences Publication Activity Database

    Ježek, Martin; Krzyszowski, A.; Zavřel, J.

    2013-01-01

    Roč. 91, 1-2 (2013), s. 177-186 ISSN 0016-8874 Institutional support: RVO:67985912 Keywords : Early Middle Ages * graveyards * touchstones * metals * electron microscopy * social structure Subject RIV: AC - Archeology, Anthropology, Ethnology

  10. AOSSM Early Sport Specialization Consensus Statement

    Science.gov (United States)

    LaPrade, Robert F.; Agel, Julie; Baker, Joseph; Brenner, Joel S.; Cordasco, Frank A.; Côté, Jean; Engebretsen, Lars; Feeley, Brian T.; Gould, Daniel; Hainline, Brian; Hewett, Timothy E.; Jayanthi, Neeru; Kocher, Mininder S.; Myer, Gregory D.; Nissen, Carl W.; Philippon, Marc J.; Provencher, Matthew T.

    2016-01-01

    Background: Early sport specialization is not a requirement for success at the highest levels of competition and is believed to be unhealthy physically and mentally for young athletes. It also discourages unstructured free play, which has many benefits. Purpose: To review the available evidence on early sports specialization and identify areas where scientific data are lacking. Study Design: Think tank, roundtable discussion. Results: The primary outcome of this think tank was that there is no evidence that young children will benefit from early sport specialization in the majority of sports. They are subject to overuse injury and burnout from concentrated activity. Early multisport participation will not deter young athletes from long-term competitive athletic success. Conclusion: Youth advocates, parents, clinicians, and coaches need to work together with the sport governing bodies to ensure healthy environments for play and competition that do not create long-term health issues yet support athletic competition at the highest level desired. PMID:27169132

  11. Early adolescent music preferences and minor delinquency.

    Science.gov (United States)

    Ter Bogt, Tom F M; Keijsers, Loes; Meeus, Wim H J

    2013-02-01

    To test Music Marker Theory (MMT) positing that early adolescents' preferences for nonmainstream types of popular music indicate concurrent and later minor delinquency. MMT was tested in a 4-year longitudinal study (n = 309). The results showed that early fans of different types of rock (eg, rock, heavy metal, gothic, punk), African American music (rhythm and blues, hip-hop), and electronic dance music (trance, techno/hardhouse) showed elevated minor delinquency concurrently and longitudinally. Preferring conventional pop (chart pop) or highbrow music (classic music, jazz), in contrast, was not related to or was negatively related to minor delinquency. Early music preferences emerged as more powerful indicators of later delinquency rather than early delinquency, indicating that music choice is a strong marker of later problem behavior. The mechanisms through which music preferences are linked to minor delinquency are discussed within the framework of MMT.

  12. Kidney Disease: Early Detection and Treatment

    Science.gov (United States)

    ... Bar Home Current Issue Past Issues Special Section Kidney Disease: Early Detection and Treatment Past Issues / Winter ... called a "urine albumin-to-creatinine ratio." Treating Kidney Disease Kidney disease is usually a progressive disease, ...

  13. Early development of the aplacophoran mollusc Chaetoderma

    DEFF Research Database (Denmark)

    Nielsen, Claus; Haszprunar, Gerhard; Ruthensteiner, Bernhard

    2007-01-01

    The early development of the trochophore larva of the aplacophoran Chaetoderma nitidulum (Mollusca: Caudofoveata = Chaetodermomorpha) is described using scanning and transmission electron microscopy and using fluorescence staining and confocal laser scanning microscopy of the muscle system...

  14. Timely Healthcare Checkup Catches Melanoma Early

    Science.gov (United States)

    ... please turn Javascript on. Feature: Skin Cancer Timely Healthcare Checkup Catches Melanoma Early Past Issues / Summer 2013 ... left the Congress and starting working as a healthcare consultant, when I finally decided to have a ...

  15. AOSSM Early Sport Specialization Consensus Statement.

    Science.gov (United States)

    LaPrade, Robert F; Agel, Julie; Baker, Joseph; Brenner, Joel S; Cordasco, Frank A; Côté, Jean; Engebretsen, Lars; Feeley, Brian T; Gould, Daniel; Hainline, Brian; Hewett, Timothy; Jayanthi, Neeru; Kocher, Mininder S; Myer, Gregory D; Nissen, Carl W; Philippon, Marc J; Provencher, Matthew T

    2016-04-01

    Early sport specialization is not a requirement for success at the highest levels of competition and is believed to be unhealthy physically and mentally for young athletes. It also discourages unstructured free play, which has many benefits. To review the available evidence on early sports specialization and identify areas where scientific data are lacking. Think tank, roundtable discussion. The primary outcome of this think tank was that there is no evidence that young children will benefit from early sport specialization in the majority of sports. They are subject to overuse injury and burnout from concentrated activity. Early multisport participation will not deter young athletes from long-term competitive athletic success. Youth advocates, parents, clinicians, and coaches need to work together with the sport governing bodies to ensure healthy environments for play and competition that do not create long-term health issues yet support athletic competition at the highest level desired.

  16. Early psychosis workforce development: Core competencies for mental health professionals working in the early psychosis field.

    Science.gov (United States)

    Osman, Helen; Jorm, Anthony F; Killackey, Eoin; Francey, Shona; Mulcahy, Dianne

    2017-08-09

    The aim of this study was to identify the core competencies required of mental health professionals working in the early psychosis field, which could function as an evidence-based tool to support the early psychosis workforce and in turn assist early psychosis service implementation and strengthen early psychosis model fidelity. The Delphi method was used to establish expert consensus on the core competencies. In the first stage, a systematic literature search was conducted to generate competency items. In the second stage, a panel consisting of expert early psychosis clinicians from around the world was formed. Panel members then rated each of the competency items on how essential they are to the clinical practice of all early psychosis clinicians. In total, 1023 pieces of literature including textbooks, journal articles and grey literature were reviewed. A final 542 competency items were identified for inclusion in the questionnaire. A total of 63 early psychosis experts participated in 3 rating rounds. Of the 542 competency items, 242 were endorsed as the required core competencies. There were 29 competency items that were endorsed by 62 or more experts, and these may be considered the foundational competencies for early psychosis practice. The study generated a set of core competencies that provide a common language for early psychosis clinicians across professional disciplines and country of practice, and potentially are a useful professional resource to support early psychosis workforce development and service reform. © 2017 John Wiley & Sons Australia, Ltd.

  17. Supersymmetry: Early Roots That Did Not Grow

    Directory of Open Access Journals (Sweden)

    Cecilia Jarlskog

    2015-01-01

    Full Text Available This paper is about early roots of supersymmetry, as found in the literature from 1940s and early 1950s. There were models where the power of “partners” in alleviating divergences in quantum field theory was recognized. However, other currently known remarkable features of supersymmetry, such as its role in the extension of the Poincaré group, were not known. There were, of course, no supersymmetric nonabelian quantum field theories in those days.

  18. Sprites and Early ionospheric VLF perturbations

    Science.gov (United States)

    Haldoupis, Christos; Amvrosiadi, Nino; Cotts, Ben; van der Velde, Oscar; Chanrion, Olivier; Neubert, Torsten

    2010-05-01

    Past studies have shown a correlation between sprites and early VLF perturbations, but the reported correlation varies widely from ~ 50% to 100%. The present study resolves these large discrepancies by analyzing several case studies of sprite and narrowband VLF observations, in which multiple transmitter-receiver VLF links with great circle paths (GCPs) passing near a sprite-producing thunderstorm were available. In this setup, the multiple links act in a complementary way that makes the detection of early VLF perturbations much more probable compared to a single VLF link that can miss several of them, a fact that was overlooked in past studies. The evidence shows that sprites are accompanied by early VLF perturbations in a one-to-one correspondence. This implies that the sprite generation mechanism may cause also sub-ionospheric conductivity disturbances that produce early VLF events. However, the one-to-one "sprite to early" event relationship, if viewed conversely as "early to sprite", appears not to be always reciprocal. This is because the number of early events detected in some cases was considerably larger than the number of sprites. Since the great majority of the early events not accompanied by sprites was caused by positive cloud to ground (+CG) lightning discharges, it is possible that sprites or sprite halos were concurrently present in these events as well but were missed by the sprite-watch detection system. In order for this option to be resolved we need more studies using highly sensitive optical systems capable of detecting weaker sprites, sprite halos and elves.

  19. Early X-ray diagnosis of coxarthrosis

    International Nuclear Information System (INIS)

    Lingg, G.; Nebel, G.

    1982-01-01

    Radiological and pathological comparisons on specimen of femurhead and neck at autopsy have shown a statistical relationship between osteophytosis of the femoral head and ulcerations of the joint cartilage. Especially there are highly significant relationships between the length of osteophytes and the diameter of the ulcera. The 'plaque'-sign shows to be a very sensitive indicator of early arthrosis. So there exist semiquantitative parameters for the X-ray diagnosis of early coxarthrosis. (orig.) [de

  20. Spotlight on daytime napping during early childhood.

    Science.gov (United States)

    Horváth, Klára; Plunkett, Kim

    2018-01-01

    Daytime napping undergoes a remarkable change in early childhood, and research regarding its relationship to cognitive development has recently accelerated. In this review, we summarize our current understanding of this relationship focusing on children aged napping status of children may modulate the relationship between learning and napping. Third, the possible role of sleep spindles, ie, specific electroencephalographic components during sleep, in cognitive development is explored. We conclude that daytime napping is crucial in early memory development.

  1. AOSSM Early Sport Specialization Consensus Statement

    OpenAIRE

    LaPrade, Robert F.; Agel, Julie; Baker, Joseph; Brenner, Joel S.; Cordasco, Frank A.; Côté, Jean; Engebretsen, Lars; Feeley, Brian T.; Gould, Daniel; Hainline, Brian; Hewett, Timothy E.; Jayanthi, Neeru; Kocher, Mininder S.; Myer, Gregory D.; Nissen, Carl W.

    2016-01-01

    © 2016 The Author(s). This is an Open Access article. Background: Early sport specialization is not a requirement for success at the highest levels of competition and is believed to be unhealthy physically and mentally for young athletes. It also discourages unstructured free play, which has many benefits. Purpose: To review the available evidence on early sports specialization and identify areas where scientific data are lacking. Study Design: Think tank, roundtable discussion...

  2. Early x-ray diagnosis of coxarthrosis

    Energy Technology Data Exchange (ETDEWEB)

    Lingg, G.; Nebel, G.

    Radiological and pathological comparisons on specimen of femur head and neck at autopsy have shown a statistical relationship between osteophytosis of the femoral head and ulcerations of the joint cartilage. Especially, there are highly significant relationships between the length of osteophytes and the diameter of the ulcera. The 'plaque'-sign is shown to be a very sensitive indicator of early arthrosis. So there exist semiquantitative parameters for the X-ray diagnosis of early coxarthrosis.

  3. Sterile neutrinos in the early universe

    Energy Technology Data Exchange (ETDEWEB)

    Malaney, R.A. (Lawrence Livermore National Lab., CA (USA)); Fuller, G.M. (California Univ., San Diego, La Jolla, CA (USA). Dept. of Physics)

    1990-11-14

    We discuss the role played by right-handed sterile neutrinos in the early universe. We show how well known {sup 4}He constraint on the number of relativistic degrees of freedom at early times limits the equilibration of the right handed neutrino sea with the background plasma. We discuss how this allows interesting constraints to be placed on neutrino properties. In particular, a new limit on the Dirac mass of the neutrino is presented. 12 refs.

  4. Early stages of technology intensive companies

    OpenAIRE

    Muhos, M. (Matti)

    2011-01-01

    Abstract This study aims to clarify the early development stages of technology intensive companies. The current literature does not offer an extensive review of stage perspectives for company growth – the overall picture of the field is somewhat vague. The evolution of this field remains unclear as well as the current state. Further, recent empirical stage models focusing on technology intensive companies have not been delineated. As companies move through their early stages, they face ev...

  5. Early detection of COPD in general practice

    DEFF Research Database (Denmark)

    Ulrik, Charlotte Suppli; Løkke, Anders; Dahl, Ronald

    2011-01-01

    Early detection enables the possibility for interventions to reduce the future burden of COPD. The Danish National Board of Health recommends that individuals >35 years with tobacco/occupational exposure, and at least 1 respiratory symptom should be offered a spirometry to facilitate early...... detection of COPD. The aim, therefore, was to provide evidence for the feasibility and impact of doing spirometry in this target population....

  6. Fluorescence photodiagnosis of early stage lung cancer

    International Nuclear Information System (INIS)

    Kato, H.; Sakai, H.; Konaka, C.; Okunaka, T.; Furukawa, K.; Saito, Y.; Aizawa, K.; Hayata, Y.

    1992-01-01

    Sputum cytology examination is the most effective method to detect early stage central type squamous cell carcinoma. As sputum-positive early stage lung cancer usually does not show any abnormal findings on chest X-ray film, fiberoptic bronchoscopy is subsequently performed for localization. However, sometimes cases do not show any abnormal findings of cancer endoscopically because they are very early stage cases. For the purpose of localization of invisible lesions the photodynamic reaction was employed in this study. Photodynamic reaction is achieved by transfer of energy of an excited photo-sensitizer induced by photoradiation of light. This phenomenon was already recognized in the beginning of this century. Study of tumor localization of the bronchial tree using hematoporphyrin derivative (HpD) and a mercury arc lamp was first performed in the Mayo Clinic in 1960s. In 1978, krypton laser was used first as a light source by Profio and Doiron. Authors have been doing research on early localization of such endoscopically occult early lung cancer since 1978. They recently developed an image processing system using an excimer dye laser for early localization of lung cancer. (author). 5 refs., 4 figs., 1 tab

  7. Designing a Free Academic Early Alert System

    Directory of Open Access Journals (Sweden)

    Adam C Welch

    2016-10-01

    Full Text Available This manuscript describes the development and implementation of a cloud-based, academic early alert system using Google Sheets. It was written for a non-computer savvy person to be able to develop the early alert system. By creating a Master Sheet and using the syntax from the share function of Google Sheets, a unique sheet can be created for each advisor that limits information sharing of their specific advisees. By adding a Google Form to the sheet, advisor interventions can be captured that reflect interventions made as a result of the early alert sheet. Approximately 52% of students were identified on the early alert sheet by having at least one non-passing score on an exam. There were 35-50% of faculty advisors who documented their interventions in the sheet. The template and coding used to develop this academic early alert sheet may be applied to other central documentation needs, such as professionalism early alert. Conflict of Interest Dr. Welch reports owning stock in Alphabet, Inc, however, was not involved in the selection of Google as the preferred platform at this institution.   Type: Note

  8. CT findings of early acute cerebral infarction

    International Nuclear Information System (INIS)

    Kim, Tae Hoon; Choi, Woo Suk; Ryu, Kyung Nam

    1992-01-01

    The CT findings of the acute cerebral infarction are well known. However the CT findings of early stroke within 24 hours of the onset have not been sufficiently reported. The purpose of this study is to evaluate early acute cerebral infarction on CT within 24 hours after ictus. The early and accurate CT diagnosis could lead to the appropriate therapy and improved outcome of the patients. Authors retrospectively analyzed 16 patients with early acute cerebral infarction. Acute cerebral infarction was confirmed by follow-up CT in 11 patients, SPECT in 4 patients, and MRI in 1 patient. The CT findings of early acute cerebral infarction include effacement of cortical sulci or cistern (n = 16, 100%), hyperattenuation of MCA (n = 3), obscuration of lentiform nucleus (n = 6), loss of insular ribbon (n = 6) and subtle low density in hemisphere (n = 5). The most frequent finding was effacement of cortical sulci in our study, and it was thought to be the most important sign of early acute cerebral infarction

  9. New Early Cycladic Figurine At Nea Styra

    Science.gov (United States)

    Kosma, M.

    The existence of an Early Bronze Age coastal site in the district of Nea Styra has been known since the end of the 19th century when three marble figurines of early Cycladic type had been found in the area. During the 20th century survey investigations conducted by Greek and foreign archaeologists offered new evidence which demonstrated the significance of the site during the Early and Middle Helladic periods. A new figurine of early Cycladic type, which recently came to light at Nea Styra due to the control of building permits by the 11th Ephorate of Prehistoric and Classical Antiquities, reaffirms the identification of the area as one of the three most important sites on Euboea during the Early Helladic II period. This paper focuses on a newly discovered figurine and its typological character. The new find is compared to the figurines that had been found in the 19th century at Nea Styra. We hope that the scheduled excavations on the private land plot where the new figurine was found will offer new data leading to a better understanding of the character of the Early Helladic settlement in this part of southern Euboea.

  10. CT findings of early acute cerebral infarction

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Tae Hoon; Choi, Woo Suk; Ryu, Kyung Nam [Kyung Hee University Hospital, Seoul (Korea, Republic of)

    1992-11-15

    The CT findings of the acute cerebral infarction are well known. However the CT findings of early stroke within 24 hours of the onset have not been sufficiently reported. The purpose of this study is to evaluate early acute cerebral infarction on CT within 24 hours after ictus. The early and accurate CT diagnosis could lead to the appropriate therapy and improved outcome of the patients. Authors retrospectively analyzed 16 patients with early acute cerebral infarction. Acute cerebral infarction was confirmed by follow-up CT in 11 patients, SPECT in 4 patients, and MRI in 1 patient. The CT findings of early acute cerebral infarction include effacement of cortical sulci or cistern (n = 16, 100%), hyperattenuation of MCA (n = 3), obscuration of lentiform nucleus (n = 6), loss of insular ribbon (n = 6) and subtle low density in hemisphere (n = 5). The most frequent finding was effacement of cortical sulci in our study, and it was thought to be the most important sign of early acute cerebral infarction.

  11. Music as therapy in early history.

    Science.gov (United States)

    Thaut, Michael H

    2015-01-01

    The notion of music as therapy is based on ancient cross-cultural beliefs that music can have a "healing" effect on mind and body. Explanations for the therapeutic mechanisms in music have almost always included cultural and social science-based causalities about the uses and functions of music in society. However, it is also important to note that the view of music as "therapy" was also always strongly influenced by the view and understanding of the concepts and causes of disease. Magical/mystical concepts of illness and "rational" medicine probably lived side by side for thousands of years. Not until the late-nineteenth and early-twentieth centuries were the scientific foundations of medicine established, which allowed the foundations of music in therapy to progress from no science to soft science and most recently to actual brain science. Evidence for "early music therapy" will be discussed in four broad historical-cultural divisions: preliterate cultures; early civilizations in Mesopotamia, Egypt, Israel; Greek Antiquity; Middle Ages, Renaissance, and Baroque. In reviewing "early music therapy" practice, from mostly unknown periods of early history (using preliterate cultures as a window) to increasingly better documented times, including preserved notation samples of actual "healing" music, five theories and applications of early music therapy can be differentiated. © 2015 Elsevier B.V. All rights reserved.

  12. Predictive factors for early menarche in Taiwan.

    Science.gov (United States)

    Chie, W C; Liu, Y H; Chi, J; Wu, V; Chen, A

    1997-06-01

    The rapid increase of breast cancer in Taiwan has prompted the authors to evaluate the predictive factors of early menarche among contemporary Taiwanese girls. A total of 895 four-grade girls from eight elementary schools in Taipei City and County were identified as a closed cohort from the first semester of 1993. Data were collected from self-administered questionnaires and school records. A total of 799 girls who had not menstruated in the first year remained in the group through 1994. The effects of potential predictive factors were assessed by logistic regression. Among the 799 girls followed, 69 (8.6%) had first menstruation between the fourth and fifth grades. Height, weight, body mass index and maternal early onset of menarche were positively related to the onset of menarche within the preceding year. Energy consumption during exercise showed only moderate association after being adjusted for age and weight. Calorie intake from junk food was not associated with early menarche within the preceding year. Poor interpersonal family relationships and stressful life events also showed a moderate association with early menarche. The data obtained supported the hypothesis that height, weight, body mass index and maternal early menarche are positive predictive factors of early menarche. The effects of exercise and childhood stress are less prominent.

  13. Early Detection of Sporadic Pancreatic Cancer

    Science.gov (United States)

    Chari, Suresh T.; Kelly, Kimberly; Hollingsworth, Michael A.; Thayer, Sarah P.; Ahlquist, David A.; Andersen, Dana K.; Batra, Surinder K.; Brentnall, Teresa A.; Canto, Marcia; Cleeter, Deborah F.; Firpo, Matthew A.; Gambhir, Sanjiv Sam; Go, Vay Liang W.; Hines, O. Joe; Kenner, Barbara J.; Klimstra, David S.; Lerch, Markus M.; Levy, Michael J.; Maitra, Anirban; Mulvihill, Sean J.; Petersen, Gloria M.; Rhim, Andrew D.; Simeone, Diane M.; Srivastava, Sudhir; Tanaka, Masao; Vinik, Aaron I.; Wong, David

    2015-01-01

    Abstract Pancreatic cancer (PC) is estimated to become the second leading cause of cancer death in the United States by 2020. Early detection is the key to improving survival in PC. Addressing this urgent need, the Kenner Family Research Fund conducted the inaugural Early Detection of Sporadic Pancreatic Cancer Summit Conference in 2014 in conjunction with the 45th Anniversary Meeting of the American Pancreatic Association and Japan Pancreas Society. This seminal convening of international representatives from science, practice, and clinical research was designed to facilitate challenging interdisciplinary conversations to generate innovative ideas leading to the creation of a defined collaborative strategic pathway for the future of the field. An in-depth summary of current efforts in the field, analysis of gaps in specific areas of expertise, and challenges that exist in early detection is presented within distinct areas of inquiry: Case for Early Detection: Definitions, Detection, Survival, and Challenges; Biomarkers for Early Detection; Imaging; and Collaborative Studies. In addition, an overview of efforts in familial PC is presented in an addendum to this article. It is clear from the summit deliberations that only strategically designed collaboration among investigators, institutions, and funders will lead to significant progress in early detection of sporadic PC. PMID:25931254

  14. Early Educational Intervention, Early Cumulative Risk, and the Early Home Environment as Predictors of Young Adult Outcomes within a High-Risk Sample

    Science.gov (United States)

    Pungello, Elizabeth P.; Kainz, Kirsten; Burchinal, Margaret; Wasik, Barbara H.; Sparling, Joseph J.; Ramey, Craig T.; Campbell, Frances A.

    2010-01-01

    The extent to which early educational intervention, early cumulative risk, and the early home environment were associated with young adult outcomes was investigated in a sample of 139 young adults (age 21) from high-risk families enrolled in randomized trials of early intervention. Positive effects of treatment were found for education attainment,…

  15. Precursors of adolescent substance use from early childhood and early adolescence: testing a developmental cascade model.

    Science.gov (United States)

    Sitnick, Stephanie L; Shaw, Daniel S; Hyde, Luke W

    2014-02-01

    This study examined developmentally salient risk and protective factors of adolescent substance use assessed during early childhood and early adolescence using a sample of 310 low-income boys. Child problem behavior and proximal family risk and protective factors (i.e., parenting and maternal depression) during early childhood, as well as child and family factors and peer deviant behavior during adolescence, were explored as potential precursors to later substance use during adolescence using structural equation modeling. Results revealed that early childhood risk and protective factors (i.e., child externalizing problems, mothers' depressive symptomatology, and nurturant parenting) were indirectly related to substance use at the age of 17 via risk and protective factors during early and middle adolescence (i.e., parental knowledge and externalizing problems). The implications of these findings for early prevention and intervention are discussed.

  16. Early Start DENVER Model: A Meta - analysis

    Directory of Open Access Journals (Sweden)

    Jane P. Canoy

    2015-11-01

    Full Text Available Each child with Autism Spectrum Disorder has different symptoms, skills and types of impairment or disorder with other children. This is why the word “spectrum” is included in this disorder. Eapen, Crncec, and Walter, 2013 claimed that there was an emerging evidence that early interventions gives the greatest capacity of child’s development during their first years of life as “brain plasticity” are high during this period. With this, the only intervention program model for children as young as 18 months that has been validated in a randomized clinical trial is “Early Start Denver Model” (ESDM. This study aimed to determine the effectiveness of the outcome of “Early Start Denver Model” (ESDM towards young children with Autism Spectrum Disorders. This study made use of meta-analysis method. In this study, the researcher utilized studies related to “Early Start Denver Model (ESDM” which is published in a refereed journal which are all available online. There were five studies included which totals 149 children exposed to ESDM. To examine the “pooled effects” of ESDM in a variety of outcomes, a meta-analytic procedure was performed after the extraction of data of the concrete outcomes. Comprehensive Meta Analysis Version 3.3.070 was used to analyze the data.  The effectiveness of the outcome of “Early Start Denver Model” towards young children with Autism Spectrum Disorders (ASD highly depends on the intensity of intervention and the younger child age. This study would provide the basis in effectively implementing an early intervention to children with autism such as the “Early Start Denver Model” (ESDM that would show great outcome effects to those children that has “Autism Spectrum Disorder”.

  17. Observations on early and delayed colostomy closure.

    Science.gov (United States)

    Tade, A O; Salami, B A; Ayoade, B A

    2011-06-01

    Traditional treatment of a variety of colorectal pathologies had included a diverting colostomy that was closed eight or more weeks later during a readmission. The aim of this retrospective study was to determine the outcomes of early colostomy closure and delayed colostomy closure in patients with temporary colostomies following traumatic and non-traumatic colorectal pathologies. In this study early colostomy closure was the closure of a colostomy within three weeks of its construction, while delayed colostomy closure referred to closure after 3 weeks. Complete records of the 37 adult patients who had temporary colostomy constructed and closed between Jan. 1997 December 2003 for various colorectal pathologies were studied. Fourteen patients had early colostomy closure while 23 had delayed closure. In the early colostomy closure group there were 10 men and 4 women. The mean age of the patients was 28yr with a range of 18-65yr. Colostomies were closed 9-18 days after initial colostomy construction. There was no mortality. Morbidity rate 28.6% (4 out of 14). There were two faecal fistulas (14.3%). Twenty-three patients had delayed colostomy closure 8 weeks to 18 months after initial colostomy construction. These were patients unfit for early surgery after initial colostomy construction because of carcinoma, significant weight loss, or sepsis. There was no mortality. Morbidity rate was 26.1%. There were 3 faecal fistulas (13.2%). Outcomes following early colostomy closure and delayed closure were comparable. Patients fit for surgery should have early closure whilst patients who may have compromised health should have delayed closure.

  18. Bipolar Disorder and Early Affective Trauma.

    Science.gov (United States)

    de Codt, Aloise; Monhonval, Pauline; Bongaerts, Xavier; Belkacemi, Ikram; Tecco, Juan Martin

    2016-09-01

    Bipolar disorder is a chronic psychiatric disease with a high prevalence and is a major psychosocial and medical burden. The exact etiological pathways of bipolar disorder are not fully understood. Genetic factors are known to play an important role in the etiology of bipolar disorder. However, high rates of discordance among identical twins and a growing body of evidence that environmental factors such as early stress can influence the onset and course of psychiatric diseases underline the importance of additional etiological mechanisms of bipolar disorders. There has been little investigation about early trauma in bipolar disorder. The aim of this study was to review the literature on the association between early traumatic interactions like child neglect, mistreatment, abuse or early parental separation and the occurrence of bipolar disorder in adulthood or impact on the course of the disease. Studies investigating associations between child neglect, mistreatment, abuse or early parental separation and occurrence of bipolar disorder in adulthood or impact on the course of the disease were searched in the Pubmed database. More than 700 articles were sorted independently by two of the authors using predefined criteria. Only research articles, reviews and meta-analyses were selected for this review. 53 articles met the inclusion criteria. To date, four systematic reviews partially addressed our research question. Early trauma is more frequently found in the past of bipolar patients than in the general population. Studies support a harmful effect of childhood trauma on the course of bipolar disease, with more anxious, depressive or psychotic symptoms, an early age of onset and a worse prognosis. Early trauma is more often found in the past of bipolar adult patients than the general population and studies support a harmful effect of childhood trauma on the course of bipolar disease, with more anxious, depressive or psychotic symptoms, an early age of onset and a

  19. Design Application Early Childhood Education Based Mobile

    Directory of Open Access Journals (Sweden)

    Annah

    2016-02-01

    Full Text Available This study aims to make learning media for Early Childhood Education in the form especially its mobile applications for Android-based smartphones. In the process of teaching and learning for Early Childhood Education is still often found constraints experienced teaching force is limited props so that learners are less eager to learn. In addition, parents also have difficulty returning to guide or teach the learning materials at home because it has no alternative instructional media. In compiling this research report author uses the Android-based Mobile Devices Applications created using the Java programming language through the Eclipse editor. Based on the results of the research, concluded that these applications can be applied in the latest version of the Android platform to its current platform version of Jellybean. Application of Learning can be used as an alternative way of learning for Early Childhood Education so as to overcome the lack of props in institutions of Early Childhood Education, can be used to be taught at home, and provide new teaching methods to early childhood so that a form of learning that is obtained is not the monotony of one form of learning how.

  20. Exemestane in early breast cancer: a review

    Directory of Open Access Journals (Sweden)

    Michael Untch

    2008-12-01

    Full Text Available Michael Untch1, Christian Jackisch21Interdisciplinary Breast Centre, Helios Klinikum Berlin-Buch, University Charité, Berlin, Germany; 2Department of Gynecology/Obstetrics, Klinikum Offenbach GmbH, Offenbach, GermanyAbstract: The adjuvant treatment of women with endocrine-sensitive early breast cancer has been dominated for the last 40 years by tamoxifen. However, the side-effects associated with this therapy have prompted a search for safer and biochemically more selective endocrine agents and led to the development of the third-generation aromatase inhibitors (AIs anastrozole, letrozole and exemestane. Promising results in advanced disease have paved the way for treating early breast cancer, and AIs are increasingly replacing tamoxifen in the adjuvant setting. Several large, randomized trials with AIs have been completed or are ongoing in women with early-stage breast cancer, documenting the significant impact that these drugs are making on the risk for recurrence of breast cancer. As a result, there is increasing and widespread use of AI therapy for the treatment of early-stage endocrine-responsive breast cancer. This review summarizes the data for exemestane in the adjuvant setting, showing that a switch to exemestane after 2 to 3 years of tamoxifen therapy is associated with a statistically significant survival benefit and is regarded as being sensitive by international and national experts.Keywords: early breast cancer, adjuvant setting, endocrine-sensitive, tamoxifen, aromatase inhibitor, exemestane, switch, IES 31, NSABP B-33, TEAM

  1. Organic and Isotopic Signatures of Life: Lessons from the Early Earth

    Science.gov (United States)

    Freeman, K. H.; Eigenbrode, J. L.; House, C. H.

    2002-12-01

    In the study of life on earth, isotopic analyses of organic biomarkers provide essential insight to their biological and environmental provenance. Isotopic analyses of organic materials on other planets present a number of challenges, both analytical and interpretive. Prebiotic planetary organic materials can derive from condensation reactions and by delivery through meteorites or interplanetary dust, with the relative importance of each influenced by the oxidation state of the atmosphere. Material delivered to planets can have an interstellar origin, although it is dominated by compounds influenced by the formation of the solar system. Each of these processes impact molecular isotopic signatures and must be considered in life-detection strategies. Pronounced effects are observed for hydrogen isotopes, with smaller fractionations observed for other elements. Theoretical, laboratory and observational studies of non-terrean materials are essential to further understand molecular isotopic heterogeneity associated with these exclusively abiotic processes. Studies of Archean-aged samples provide an important resource for interpreting molecular isotopic patterns as signatures of life processes. Carbon assimilation and biomass synthesis from simple precursor compounds typically discriminate against 13C. This generality, however, is complicated by the observations of a wide range of fractionation factors associated with important microbial carbon-uptake processes. Metabolic processes further distribute isotopic signatures, such that wide isotopic heterogeneity is observed among cellular biochemical constituents. In addition, preservation/contamination concerns dominate studies of very ancient organic matter, as they likely will in life-detection studies. However, both biochemical heterogeneity and sample integrity can be addressed by considering patterns from different paleoenvironments. Molecular results demonstrate that Late Archean microbial life on this planet was

  2. Early diagnosis and screening for colorectal cancer

    International Nuclear Information System (INIS)

    Laufer, I.

    1986-01-01

    The barium enema has been a neglected tool in the diagnosis of early colon cancer. With appropriate attention to technical detail, the double contrast enema is capable of detecting the smallest malignant and pre-malignant lesions. Many of these early colon cancers are found in asymptomatic patients and these lesions are curable. The goal of a screening program should be to identify by history or by fecal occult blood testing patients at high risk for the development of colon cancer. These patients should be examined by high-quality double contrast enema in the search for these potentially lethal but curable lesions. In addition, we believe that any patient undergoing radiologic examination of the colon for whatever reason, should receive an examination of adequate quality to rule out an early colon cancer. (Author)

  3. The radiology of early esophageal cancer

    International Nuclear Information System (INIS)

    Uematsu, S.

    1988-01-01

    The radiographic diagnosis of early esophageal cancer is described based on 25 cases in which depth of invasion was limited to not more than the submucosal layer. It is emphasized that double contrast radiography should be designed to delineate the subtle abnormalities of the esophageal mucosa and margins of lesions which are characteristic of early cancer, and that further investigation should be directed to improving the method of examination so that the detection of ep- and mm-cancer which has a better prognosis than sm cancer can be detected more readily. A macroscopic classification of early esophageal cancer (elevated, flat, depressed and mixed type) which is useful for both endoscopic and radiographic diagnosis is proposed. The 5-year survival rate of esophageal cancer which was limited to the submucosal layer or less (ep-, mm- and sm-cancer) was 50%

  4. Early executive function predicts reasoning development.

    Science.gov (United States)

    Richland, Lindsey E; Burchinal, Margaret R

    2013-01-01

    Analogical reasoning is a core cognitive skill that distinguishes humans from all other species and contributes to general fluid intelligence, creativity, and adaptive learning capacities. Yet its origins are not well understood. In the study reported here, we analyzed large-scale longitudinal data from the Study of Early Child Care and Youth Development to test predictors of growth in analogical-reasoning skill from third grade to adolescence. Our results suggest an integrative resolution to the theoretical debate regarding contributory factors arising from smaller-scale, cross-sectional experiments on analogy development. Children with greater executive-function skills (both composite and inhibitory control) and vocabulary knowledge in early elementary school displayed higher scores on a verbal analogies task at age 15 years, even after adjusting for key covariates. We posit that knowledge is a prerequisite to analogy performance, but strong executive-functioning resources during early childhood are related to long-term gains in fundamental reasoning skills.

  5. International Orders in the Early Modern World

    DEFF Research Database (Denmark)

    This book challenges the Eurocentric foundations of modern International Relations scholarship. Its primary empirical focus is the early modern era, when European primacy had yet to develop in many parts of the globe. It presents a series of regional case studies from experts on East Asia, the Mi...... and scholars of international relations, international relations theory, international history, early modern history and sociology.......This book challenges the Eurocentric foundations of modern International Relations scholarship. Its primary empirical focus is the early modern era, when European primacy had yet to develop in many parts of the globe. It presents a series of regional case studies from experts on East Asia......, the Middle East, Africa and Latin America, and Russia to explore patterns of cross-cultural exchange and civilizational encounters. The authors analyze a series of regional international orders which were primarily defined by local interests, agendas and institutions, with European interlopers often playing...

  6. Bursts from the very early universe

    International Nuclear Information System (INIS)

    Silk, J.; Stodolsky, L.

    2006-01-01

    Bursts of weakly interacting particles such as neutrinos or even more weakly interacting particles such as wimps and gravitons from the very early universe would offer a much deeper 'look back time' to early epochs than is possible with photons. We consider some of the issues related to the existence of such bursts and their detectability. Characterizing the burst rate by a probability P per Hubble four-volume we find, for events in the radiation-dominated era, that the natural unit of description is the present intensity of the CMB times P. The existence of such bursts would make the observation of phenomena associated with very early times in cosmology at least conceptually possible. One might even hope to probe the transplanckian epoch if complexes more weakly interacting than the graviton can exist. Other conceivable applications include the potential detectability of the formation of 'pocket universes' in a multiverse

  7. Bursts from the very early universe

    Energy Technology Data Exchange (ETDEWEB)

    Silk, J. [Department of Physics, University of Oxford, Oxford OX1 3RH (United Kingdom); Stodolsky, L. [Max-Planck-Institut fuer Physik, Foehringer Ring 6, 80805 Munich (Germany)]. E-mail: les@mppmu.mpg.de

    2006-07-27

    Bursts of weakly interacting particles such as neutrinos or even more weakly interacting particles such as wimps and gravitons from the very early universe would offer a much deeper 'look back time' to early epochs than is possible with photons. We consider some of the issues related to the existence of such bursts and their detectability. Characterizing the burst rate by a probability P per Hubble four-volume we find, for events in the radiation-dominated era, that the natural unit of description is the present intensity of the CMB times P. The existence of such bursts would make the observation of pheno associated with very early times in cosmology at least conceptually possible. One might even hope to probe the transplanckian epoch if complexes more weakly interacting than the graviton can exist. Other conceivable applications include the potential detectability of the formation of 'pocket universes' in a multiverse.

  8. Hormone patterns in early human gestation

    International Nuclear Information System (INIS)

    Mishell, D.R. Jr.; Thorneycroft, I.H.; Nagata, Y.; Murata, T.; Nakamura, R.M.

    1974-01-01

    Accurate measurement of the low concentration of gonadotropins and steroid hormones present in human serum has been made possible by the development of sensitive radioimmunoassay (RIA) techniques. With the use of RIA FSH and LH, progesterone and 17OH-progesterone have been previously measured in early normal pregnancy. In order to determine the daily pattern of hormone levels in early normal pregnancy, gonadotropins as well as steroid hormone levels were measured in serum samples obtained daily from three women from the time of the last menstrual period prior to conception throughout the first few months of gestation. To further identify the steroid hormone pattern in early normal pregnancy, concentrations of estradiol, progesterone, and 17OH-progesterone were measured in individual serum samples obtained from a group of 158 women with apparently normal gestations who subsequently had therapeutic abortions. (auth)

  9. Autism: cause factors, early diagnosis and therapies.

    Science.gov (United States)

    Bhat, Shreya; Acharya, U Rajendra; Adeli, Hojjat; Bairy, G Muralidhar; Adeli, Amir

    2014-01-01

    Autism spectrum disorder (ASD) is a complex neurobiological disorder characterized by neuropsychological and behavioral deficits. Cognitive impairment, lack of social skills, and stereotyped behavior are the major autistic symptoms, visible after a certain age. It is one of the fastest growing disabilities. Its current prevalence rate in the U.S. estimated by the Centers for Disease Control and Prevention is 1 in 68 births. The genetic and physiological structure of the brain is studied to determine the pathology of autism, but diagnosis of autism at an early age is challenging due to the existing phenotypic and etiological heterogeneity among ASD individuals. Volumetric and neuroimaging techniques are explored to elucidate the neuroanatomy of the ASD brain. Nuroanatomical, neurochemical, and neuroimaging biomarkers can help in the early diagnosis and treatment of ASD. This paper presents a review of the types of autism, etiologies, early detection, and treatment of ASD.

  10. Tracing Early Interventions on Childhood Overweight

    DEFF Research Database (Denmark)

    Ditlevsen, Kia

    This thesis presents results from a qualitative research project on early interventions to counter childhood obesity in Denmark. Overall, it was found that these interventions in families with preschool children were rarely performed. One barrier to the interventions is the structural setting...... in families with a non-western ethnic minority background and with low socioeconomic status. In families who participated in interventions, other social problems and a sense of insecurity caused by precarious living conditions of different kinds influenced the parents’ readiness to restrict children in order...... in the Danish health care system, which was found to be insufficient to initiate and facilitate early interventions. In addition, cultural stereotypes were found to affect the health care practitioners who are performing early interventions, and this can create reluctance to address overweight problems...

  11. Synthesis of IES Research on Early Intervention and Early Childhood Education. NCSER 2013-3001

    Science.gov (United States)

    Diamond, Karen E.; Justice, Laura M.; Siegler, Robert S.; Snyder, Patricia A.

    2013-01-01

    A primary purpose of early childhood education and interventions is to promote children's acquisition of knowledge and skills linked to later social competence and academic success. In this report, special attention is given to summarizing what has been learned about early childhood classrooms as contexts for development and learning, the kinds of…

  12. Early Childhood Development and E-Learning in Africa: The Early Childhood Development Virtual University Programme

    Science.gov (United States)

    Pence, Alan

    2007-01-01

    This article explores the development and evaluation of the graduate-level Early Childhood Development Virtual University (ECDVU) programme in Sub-Saharan Africa from 2001 through to 2004. It outlines the history of the ECDVU and the establishing of a Sub-Saharan programme for future leaders in the early childhood field guided by the key principle…

  13. Explaining Why Early-Maturing Girls Are More Exposed to Sexual Harassment in Early Adolescence

    Science.gov (United States)

    Skoog, Therése; Bayram Özdemir, Sevgi

    2016-01-01

    In this study, we tested two competing explanations of the previously established link between early female puberty and sexual harassment in early adolescence. The sample included 680 seventh-grade Swedish girls (M[subscript age] = 13.40, SD = 0.53). Findings revealed that looking more sexually mature and being sexually active mediated the link…

  14. Early College for All: Efforts to Scale up Early Colleges in Multiple Settings

    Science.gov (United States)

    Edmunds, Julie A.

    2016-01-01

    Given the positive impacts of the small, stand-alone early college model and the desire to provide those benefits to more students, organizations have begun efforts to scale up the early college model in a variety of settings. These efforts have been supported by the federal government, particularly by the Investing in Innovation (i3) program.…

  15. Clarifying Parent-Child Reciprocities during Early Childhood: The Early Childhood Coercion Model

    Science.gov (United States)

    Scaramella, Laura V.; Leve, Leslie D.

    2004-01-01

    Consistent with existing theory, the quality of parent-child interactions during early childhood affects children's social relationships and behavioral adjustment during middle childhood and adolescence. Harsh parenting and a propensity toward emotional overarousal interact very early in life to affect risk for later conduct problems. Less…

  16. Family Income Dynamics, Early Childhood Education and Care, and Early Child Behavior Problems in Norway

    Science.gov (United States)

    Zachrisson, Henrik D.; Dearing, Eric

    2015-01-01

    The sociopolitical context of Norway includes low poverty rates and universal access to subsidized and regulated Early Childhood Education and Care (ECEC). In this context, the association between family income dynamics and changes in early child behavior problems was investigated, as well as whether high-quality ECEC buffers children from the…

  17. Early Rehabilitation After Stroke: a Narrative Review.

    Science.gov (United States)

    Coleman, Elisheva R; Moudgal, Rohitha; Lang, Kathryn; Hyacinth, Hyacinth I; Awosika, Oluwole O; Kissela, Brett M; Feng, Wuwei

    2017-11-07

    Despite current rehabilitative strategies, stroke remains a leading cause of disability in the USA. There is a window of enhanced neuroplasticity early after stroke, during which the brain's dynamic response to injury is heightened and rehabilitation might be particularly effective. This review summarizes the evidence of the existence of this plastic window, and the evidence regarding safety and efficacy of early rehabilitative strategies for several stroke domain-specific deficits. Overall, trials of rehabilitation in the first 2 weeks after stroke are scarce. In the realm of very early mobilization, one large and one small trial found potential harm from mobilizing patients within the first 24 h after stroke, and only one small trial found benefit in doing so. For the upper extremity, constraint-induced movement therapy appears to have benefit when started within 2 weeks of stroke. Evidence for non-invasive brain stimulation in the acute period remains scant and inconclusive. For aphasia, the evidence is mixed, but intensive early therapy might be of benefit for patients with severe aphasia. Mirror therapy begun early after stroke shows promise for the alleviation of neglect. Novel approaches to treating dysphagia early after stroke appear promising, but the high rate of spontaneous improvement makes their benefit difficult to gauge. The optimal time to begin rehabilitation after a stroke remains unsettled, though the evidence is mounting that for at least some deficits, initiation of rehabilitative strategies within the first 2 weeks of stroke is beneficial. Commencing intensive therapy in the first 24 h may be harmful.

  18. Roentgenographic diagnosis of early stomach cancer

    International Nuclear Information System (INIS)

    Suh, Jung Ho; Choi, Byung Sook; Choi, Heung Jai

    1970-01-01

    The most significant feature of early carcinoma, be defined as the gastric carcinoma confined in mucosa and submucosal regardless of its size and shape, is its excellent prognosis; 5 year survival rate after operation in early stomach carcinoma amounts to 93 percent in comparison with around 25 percent in advanced carcinoma, and so the detection of this early stomach carcinoma is most important subject to minimize the mortality from stomach carcinoma at the present time. For the diagnosis of the early stomach carcinoma the radiographic study, cytology and gastroscopic examination are practised, and of those the radiographic study has been revealed commonly best results, but by usual method of upper G-I study it is often difficult to diagnose accurately. Therefore, we have been employed the barium and air double contrast method by insertion of the gastric tube. This method is simple and by this method, the adequate amount of air may introduced into the stomach for the best visualization of the mucosal pattern and gastric juice may also aspirated in a case of which the stomach wall could not be coated by barium because of excessive gastric juice. Summary of the results of this studies of early carcinoma detection at the department of radiology, Severance Hospital during 6 months since May 1969 are as followings; of 1407 cases taken upper G-I study with double contrast method, 17 cases were diagnosed as possible early stomach carcinoma radiographically, and then only 6 cases had surgical resection of stomach. Of these 2 cases were confirmed pathologically and one was considered as precancerots lesion

  19. Roentgenographic diagnosis of early stomach cancer

    Energy Technology Data Exchange (ETDEWEB)

    Suh, Jung Ho; Choi, Byung Sook; Choi, Heung Jai [Yonsei University College of Medicine, Seoul (Korea, Republic of)

    1970-10-15

    The most significant feature of early carcinoma, be defined as the gastric carcinoma confined in mucosa and submucosal regardless of its size and shape, is its excellent prognosis; 5 year survival rate after operation in early stomach carcinoma amounts to 93 percent in comparison with around 25 percent in advanced carcinoma, and so the detection of this early stomach carcinoma is most important subject to minimize the mortality from stomach carcinoma at the present time. For the diagnosis of the early stomach carcinoma the radiographic study, cytology and gastroscopic examination are practised, and of those the radiographic study has been revealed commonly best results, but by usual method of upper G-I study it is often difficult to diagnose accurately. Therefore, we have been employed the barium and air double contrast method by insertion of the gastric tube. This method is simple and by this method, the adequate amount of air may introduced into the stomach for the best visualization of the mucosal pattern and gastric juice may also aspirated in a case of which the stomach wall could not be coated by barium because of excessive gastric juice. Summary of the results of this studies of early carcinoma detection at the department of radiology, Severance Hospital during 6 months since May 1969 are as followings; of 1407 cases taken upper G-I study with double contrast method, 17 cases were diagnosed as possible early stomach carcinoma radiographically, and then only 6 cases had surgical resection of stomach. Of these 2 cases were confirmed pathologically and one was considered as precancerots lesion.

  20. THE LONG REACH OF EDUCATION: EARLY RETIREMENT.

    Science.gov (United States)

    Venti, Steven; Wise, David A

    2015-12-01

    The goal of this paper is to draw attention to the long lasting effect of education on economic outcomes. We use the relationship between education and two routes to early retirement - the receipt of Social Security Disability Insurance (DI) and the early claiming of Social Security retirement benefits - to illustrate the long-lasting influence of education. We find that for both men and women with less than a high school degree the median DI participation rate is 6.6 times the participation rate for those with a college degree or more. Similarly, men and women with less than a high school education are over 25 percentage points more likely to claim Social Security benefits early than those with a college degree or more. We focus on four critical "pathways" through which education may indirectly influence early retirement - health, employment, earnings, and the accumulation of assets. We find that for women health is the dominant pathway through which education influences DI participation. For men, the health, earnings, and wealth pathways are of roughly equal magnitude. For both men and women the principal channel through which education influences early Social Security claiming decisions is the earnings pathway. We also consider the direct effect of education that does not operate through these pathways. The direct effect of education is much greater for early claiming of Social Security benefits than for DI participation, accounting for 72 percent of the effect of education for men and 67 percent for women. For women the direct effect of education on DI participation is not statistically significant, suggesting that the total effect may be through the four pathways.

  1. Challenges of Early Years Leadership Preparation: A Comparison between Early and Experienced Early Years Practitioners in England

    Science.gov (United States)

    Mistry, Malini; Sood, Krishan

    2012-01-01

    Leadership has been under-researched in the Early Years (EY) sector of primary schools in England, especially in leading change for professional development. The aim of this paper is to theorise what the leadership culture for EY practitioners looks like, and how Initial Teacher Training providers and schools are preparing practitioners for…

  2. Salivary cytokine levels in early gingival inflammation

    DEFF Research Database (Denmark)

    Belstrøm, Daniel; Damgaard, Christian; Könönen, Eija

    2017-01-01

    Salivary protein levels have been studied in periodontitis. However, there is lack of information on salivary cytokine levels in early gingival inflammation. The aim of this study was to determine salivary levels of vascular endothelial growth factor (VEGF), interleukin (IL)-8, monocyte chemoattr......Salivary protein levels have been studied in periodontitis. However, there is lack of information on salivary cytokine levels in early gingival inflammation. The aim of this study was to determine salivary levels of vascular endothelial growth factor (VEGF), interleukin (IL)-8, monocyte...

  3. [Early diagnosis of autism: Phenotype-endophenotype].

    Science.gov (United States)

    Kotsopoulos, S

    2015-01-01

    Autism Spectrum Disorders have for some time been the focus of intense interest for clinicians and researchers because of the high prevalence of the disorders among children in the community (approximately 1%), their severity and pervasiveness. Particular attention has been paid to the early diagnosis of the disorder and to the intensive therapeutic intervention. Currently the best prognosis for autism lays in the early diagnosis and intervention. Postponing the diagnosis and the intervention beyond infancy is considered loss of precious time. The diagnosis of autism, which begins early in life, was until recently considered that could be reliability made at the age of 3 years. Recent follow up studies however on children at risk for autism (children who had an older sibling with autism) have shown that the clinical signs of autism emerge at the end of the first year and become distinct by the end of the second year when the diagnosis can reliably be made. From a clinical perspective it is noted that the early clinical signs of risk for autism are related to social communication (e.g. limited or absent response when calling his/her name and to joint attention), stereotype behaviours and body movements or unusual handling of objects (e.g. intensive observation of objects and stereotype movements of hands and tapping or spinning), incongruent regulation of emotions (reduced positive and increased negative emotion). There is also delay in developmental characteristics such as the language (both receptive and expressive) and motor (particularly in postural control - characteristic is the drop of the head backwards when the infant is held in horizontal position). Studies on various aspects of the endophenotype of certain clinical signs among infants at risk for Autism Spectrum Disorders, such as avoidance of eye contact, delay in verbal communication and increase of the head circumference, may provide useful information and may assist the clinician on follow up in the

  4. The Effect of Early Entrepreneurship Education

    DEFF Research Database (Denmark)

    Huber, Laura Rosendahl; Sloof, Randolph; Van Praag, Mirjam

    2014-01-01

    The aim of this study is to analyze the effectiveness of early entrepreneurship education. To this end, we conduct a randomized field experiment to evaluate a leading entrepreneurship education program that is taught worldwide in the final grade of primary school. We focus on pupils׳ development...... or negative effects. Because these earlier studies all pertain to entrepreneurship education for adolescents, our result tentatively suggests that non-cognitive entrepreneurial skills are best developed at an early age. As the entrepreneurship program has various features besides its entrepreneurship content...

  5. ENDOSCOPIC TECHNOLOGIES IN EARLY RECTAL CANCER TREATMENT

    Directory of Open Access Journals (Sweden)

    D. V. Samsonov

    2015-01-01

    Full Text Available Total mesorectal excision is the “golden standard” of surgical treatment for rectal cancer. Development of endoscopic technologies allowed to implement the benefits of minimally invasive surgery in early rectal cancer treatment, decrease morbidity and mortality, improve functional outcome and quality of life. Oncological safety of this method is still a subject for discussion due to lack of lymph node harvest. Endoscopic operations for early rectal cancer are being actively implemented in daily practice, but lack of experience does not allow to include this method in national clinical prac-tice guidelines.

  6. Sensors Provide Early Warning of Biological Threats

    Science.gov (United States)

    2009-01-01

    Early Warning Inc. of Troy, New York, licensed powerful biosensor technology from Ames Research Center. Incorporating carbon nanotubes tipped with single strands of nucleic acid from waterborne pathogens, the sensor can detect even minute amounts of targeted, disease causing bacteria, viruses, and parasites. Early Warning features the NASA biosensor in its water analyzer, which can provide advance alert of potential biological hazards in water used for agriculture, food and beverages, showers, and at beaches and lakes -- within hours instead of the days required by conventional laboratory methods.

  7. The Toy model: Understanding the early universe

    Science.gov (United States)

    Fisher, Peter H.; Price, Richard H.

    2018-04-01

    In many branches of science, progress is being made by taking advantage of insights from other branches of science. Cosmology, the structure and evolution of the universe, is certainly an area that is currently beset by problems in understanding. We show here that the scientific insights from the studies of early childhood development, in particular, those of Piaget, give a new way of looking at the early universe. This new approach can not only be invaluable in undergraduate teaching, but can even be the basis of semi-quantitative predictions.

  8. Designing a Free Academic Early Alert System

    OpenAIRE

    Adam C Welch; Adam Greever; Carmen Linne

    2016-01-01

    This manuscript describes the development and implementation of a cloud-based, academic early alert system using Google Sheets. It was written for a non-computer savvy person to be able to develop the early alert system. By creating a Master Sheet and using the syntax from the share function of Google Sheets, a unique sheet can be created for each advisor that limits information sharing of their specific advisees. By adding a Google Form to the sheet, advisor interventions can be captured tha...

  9. Genomes of early onset prostate cancer

    DEFF Research Database (Denmark)

    Weischenfeldt, Joachim; Korbel, Jan O.

    2017-01-01

    Purpose of review Prostate cancer is a disease of the elderly but a clinically relevant subset occurs early in life. In the current review, we discuss recent findings and the current understanding of the molecular underpinnings associated with early-onset prostate cancer (PCa) and the evidence...... supporting age-specific differences in the cancer genomes. Recent findings Recent surveys of PCa patient cohorts have provided novel age-dependent links between germline and somatic aberrations which points to differences in the molecular cause and treatment options. Summary Identifying the earliest...... receptor pathway....

  10. The early use of radiotracers in chemistry

    International Nuclear Information System (INIS)

    Grabowski, K.F.M.

    1986-01-01

    This article describes the historical background to the use of radiotracers, pioneered by de Hevesy and Paneth before World War I. It traces their early use in ion and metal interchange in electrolysis, self-diffusion rates, early biochemical experiments on lead uptake in plants, phosphorus metabolism in rats, through to their wider use with the production of artificial radioisotopes after World War II. Photosynthesis experiments using carbon-11 and carbon-14 are described and their present-day widespread use in kinetics, metabolic pathway studies and therapeutics is discussed. (UK)

  11. Use of red ochre by early Neanderthals

    DEFF Research Database (Denmark)

    Nielsen, Trine Kellberg

    2012-01-01

    The use of manganese and iron oxides by late Neandertals is well documented in Europe, especially for the period 60–40 kya. Such finds often have been interpreted as pigments even though their exact function is largely unknown. Here we report significantly older iron oxide finds that constitute t...... dozens of kilometers. Identification of the Maastricht-Belvédère finds as hematite pushes the use of red ochre by (early) Neandertals back in time significantly, to minimally 200–250 kya (i.e., to the same time range as the early ochre use in the African record)....

  12. Complex Foot Injury: Early and Definite Management.

    Science.gov (United States)

    Schepers, Tim; Rammelt, Stefan

    2017-03-01

    Complex foot injuries occur infrequently, but are life-changing events. They often present with other injuries as the result of a high-energy trauma. After initial stabilization, early assessment should be regarding salvagability. All treatment strategies are intensive. The initial treatment includes prevention of progression ischemia/necrosis, prevention of infection, and considering salvage or amputation. Definitive treatment for salvage includes anatomic reconstruction with stable internal fixation and early soft tissue coverage followed by aggressive rehabilitation. Prognosis after complex injuries is hard to predict. The various stages of the treatment are reviewed and recommendations are made. Copyright © 2016 Elsevier Inc. All rights reserved.

  13. Early Labour Market Returns to College Subject

    DEFF Research Database (Denmark)

    Buonanno, Paolo; Pozzoli, Dario

    2009-01-01

    We estimate early labour market outcomes of Italian university  graduates across college subjects. We devote great attention to endogenous selection issues using alternative methods to control for potential self-selection associated with the choice of the degree subject in order to unravel...... the causal link between college major and subsequent outcomes in the labour market. Our results suggest that 'quantitative' fields (i.e. Sciences, Engineering, and Economics) increase not only the speed of transition into the first job and employment probability but also early earnings, conditional...

  14. Early labour market returns to college subjects

    DEFF Research Database (Denmark)

    Buonanno, Paolo; Pozzoli, Dario

    This paper aims at estimating early labour market outcomes  of Italian university graduates across college subjects. We devote great attention to endogenous selection issues using alternative methods to control for potential self-selection associated with the choice of the degree subject in order...... to unravel the causal link between college major and subsequent outcomes in the labour market.  Our results suggest that "quantitative" fields (i.e. Sciences, Engineering and Economics) increase not only the speed of transition into the first job and employment probability but also early earnings...

  15. Pathologic features of early inflammatory bowel disease.

    Science.gov (United States)

    Finkelstein, Sydney D; Sasatomi, Eizaburo; Regueiro, Miguel

    2002-03-01

    Often the pathologic changes of IBD are subtle and may not be present in a proportion of biopsy specimens. In cases of early disease, the changes may be missed, and additional specimens should be taken after a period of time. Modifying factors, such as prebiopsy treatment and coexisting disease, should be considered. A forum to review cases and allow for communication between gastroenterologists and pathologists is especially useful for clinicopathologic correlation and assignment of a working diagnosis to each case. Careful attention to the pathologic features of early UC and CD would be most useful when evaluating new therapies for IBD.

  16. Early-type semidetached system LY Aurigae

    International Nuclear Information System (INIS)

    Li, Y.F.; Leung, K.C.

    1985-01-01

    In an effort to resolve a controversy regarding the configuration, mass ratio, and evolutionary status of the early-type close binary system LY Aur, the six bandpass OAO 2 observations of Heap and the ground-based observations combined by Eaton were analyzed. The Wilson and Devinney approach was used. The system is found to be semidetached, with the cooler and less massive component filling its Roche lobe, while the hotter component is close to its Roche surface. The system is not an early-type zero-age contact, as was suspected earlier. 20 references

  17. PROBLEM OF DIAGNOSIS OF EARLY CONGENITAL SYPHILIS

    Directory of Open Access Journals (Sweden)

    G. P. Martynova

    2013-01-01

    Full Text Available The paper presents a case of delayed diagnosis of early congenital syphilis in a child whose mother was observed in prenatal clinic starting from the 14th week of pregnancy. The child had specific skin rash already in maternity. The child was discharged home without examination in the hospital. Only manifestations of nephritis lead to admission of the child into an inpatient hospital. Only at the age of 1 month and 23 days the child was suspected of early congenital syphilis with severe polisimptomnym, and the patient was transferred to specialized hospital. 

  18. WMAP - A Glimpse of the Early Universe

    Science.gov (United States)

    Wollack, Edward

    2009-01-01

    The early Universe was incredibly hot, dense, and homogeneous. A powerful probe of this time is provided by the relic radiation which we refer to today as the Cosmic Microwave Background (CMB). Images produced from this light contain the earliest glimpse of the Universe after the "Big Bang" and the signature of the evolution of its contents. By exploiting these clues, precise constraints on the age, mass density, and geometry of the early Universe can be derived. The history of this intriguing cosmological detective story will be reviewed. Recent results from NASA's Wilkinson Microwave Anisotropy Probe (WMAP) will be presented.

  19. Supersymmetry in the very early universe

    International Nuclear Information System (INIS)

    Thomas, S.

    1995-06-01

    Supersymmetric flat directions can have a number of important consequences in the very early universe. Depending on the form of the SUSY breaking potential arising from the finite energy density at early times, coherent production of scalar condensates can result along such directions. This leads a cosmological disaster for Polonyi type flat directions with only Planck suppressed couplings, but can give rise to the baryon asymmetry for standard model flat directions. Flat directions are also natural candidates to act as inflatons. Achieving density fluctuations of the correct magnitude generally requires an additional hidden SUSY breaking sector

  20. The challenge of early surgery for cryptorchidism

    DEFF Research Database (Denmark)

    Thorup, Jørgen Mogens; Jensen, C.L.; Langballe, O

    2011-01-01

    Objective. In congenital cryptorchidism, a recent Nordic Consensus report recommends surgical correction at 6–12 months of age to prevent male infertility. In published series of orchiopexies the median age at surgery is often 3 years or more. The aim of this study was to evaluate whether early...... centres is important when treating cryptorchidism with early surgery, otherwise the positive beneficial biological impact on fertility potential may be lost due to treatment failure. Read More: http://informahealthcare.com/doi/abs/10.3109/00365599.2010.549091...