22,973 research outputs found

    Extreme ultraviolet emission lines of Ni XII in laboratory and solar spectra

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    Wavelengths for emission lines arising from 3s23p5-3s3p6 and 3s23p5-3s23p43d transitions in Ni XII have been measured in extreme ultraviolet spectra of the Joint European Torus(JET) tokamak. The 3s23p5 2P1/2-3s23p4(3P)3d 2D3/2 line is found to lie at 152.90 ± 0.02 A, a significant improvement over the previous experimental determination of 152.95 ± 0.5 A. This new wavelength is in good agreement with a solar identification at 152.84 ± 0.06 A, confirming the presence of this line in the solar spectrum. The Ni XII feature at 152.15 A may be a result only of the 3s23p5 2P3/2-3s23p4(3P)3d 2D5/2 transition, rather than a blend of this line with 3s23p5 2P3/2-3s23p (3P)3d 2P1/2, as previously suggested. Unidentified emission lines at 295.32 and 317.61 A in solar flare spectra from the Skylab mission are tentatively identified as the 3s23p5 2P3/2-3s3p6 2S1/2 and 3s23p5 2P1/2-3s3p6 2S1/2 transitions in Ni XII, which have laboratory wavelengths of 295.33 and 317.50 A, respectively. Additional support for these identifications is provided by the line intensity ratio for the solar features, which shows good agreement between theory and observation

    Scaling graphs of heart rate time series in athletes demonstrate the VLF, LF and HF regions

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    Scaling analysis of heart rate time series has emerged as an useful tool for assessment of autonomic cardiac control. We investigate the heart rate time series of ten athletes (five males and five females), by applying detrended fluctuation analysis (DFA). High resolution ECGs are recorded under standardized resting conditions over 30 minutes and subsequently heart rate time series are extracted and artefacts filtered. We find three distinct regions of scale-invariance, which correspond to the well-known VLF, LF, and HF bands in the power spectra of heart rate variability. The scaling exponents alpha are alphaHF: 1.15 [0.96-1.22], alphaLF: 0.68 [0.57-0.84], alphaVLF: 0.83[0.82-0.99]; p<10^-5). In conclusion, DFA scaling exponents of heart rate time series should be fitted to the VLF, LF, and HF ranges, respectively

    AJAE Appendix: Challenges to the Development of a Dedicated Energy Crop

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    The material contained herein is supplementary to the article named in the title and published in the American Journal of Agricultural Economics, Volume 89, Number 5, December 2007.Crop Production/Industries, Research and Development/Tech Change/Emerging Technologies,

    Adaptive Significance of Natural Variations in Maternal Care in Rats: A Translational Perspective

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    A wealth of data from the last fifty years documents the potency of early life experiences including maternal care on developing offspring. A majority of this research has focused on the developing stress axis and stress-sensitive behaviors in hopes of identifying factors impacting resilience and risk-sensitivity. The power of early life experience to shape later development is profound and has the potential to increase fitness of individuals for their environments. Current findings in a rat maternal care paradigm highlight the complex and dynamic relation between early experiences and a variety of outcomes. In this review we propose adaptive hypotheses for alternate maternal strategies and resulting offspring phenotypes, and ways to distinguish between these hypotheses. We also provide evidence underscoring the critical role of context in interpreting the adaptive significance of early experiences. If our goal is to identify risk-factors relevant to humans, we must better explore the role of the social and physical environment in our basic animal models

    A continental rift model for the La Grande greenstone belt

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    Stratigraphic relationships and the geochemistry of volcanic rocks contrain the nature and timing of the tectonic and magmatic processes in the pre-deformational history of the La Grande greenstone belt in the Superior Province of north-central Quebec. The lowermost supracrustals in this belt are obscured by syntectonic granitoid intrusives. The supracrustal succession in the western part of the belt consists of a lower sequence of immature clastic sediments and mafic volcanoclastics, overlain by pillowed and massive basalts. Further east, along tectonic strike, a lower sequence of mafic volcanoclastics and immature clastic sediments is overlain by a thick sequence of pillowed and massive basalts, and resedimented coarse clastic sediments and banded iron formation. These are overlain by assive basaltic andesites, andesites and intermediate volcanoclastics intercalated with immature clastic sediments. In contrast, in the eastern part of the belt lenses of felsic volcanics and volcanoclastics occur at the base of the succession and pillowed and massive basalts are overlain by komatiites at the top. The La Grande greenstone belt can be explained as the product of continental rifting. The restricted occurence of komatiites, and eastwardly directed paleocurrents in clastic sediments in the central part of the belt are consistent with rifting commencing in the east and propagating westward with time. The increase in depth of emplacement and deposition with time of the lower three units in the central part of the belt reflects deposition in a subsiding basin. These supracrustal rocks are believed to represent the initial rift succession

    A comparison of theoretical line intensity ratios for Ni XII with extreme ultraviolet observations from the JET tokamak

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    Recent R-matrix calculations of electron impact excitation rates in Ni XII are used to derive the emission line ratios R1 = I (154.17 Å)/I (152.15 Å), R2 = I (152.95 Å)/I (152.15 Å) and R3 = I (160.55 Å)/I (152.15 Å). This is the first time (to our knowledge) that theoretical emission line ratios have been calculated for this ion. The ratios are found to be insensitive to changes in the adopted electron density (Ne) when Ne >= 5 × 10^11 cm−3, typical of laboratory plasmas. However, they do vary with electron temperature (Te), with for example R1 and R3 changing by factors of 1.3 and 1.8, respectively, between Te = 10^5 and 10^6 K. A comparison of the theoretical line ratios with measurements from the Joint European Torus (JET) tokamak reveals very good agreement between theory and observation for R1, with an average discrepancy of only 7%. Agreement between the calculated and experimental ratios for R2 and R3 is less satisfactory, with average differences of 30 and 33%, respectively. These probably arise from errors in the JET instrument calibration curve. However, the discrepancies are smaller than the uncertainties in the R2 and R3 measurements. Our results, in particular for R1, provide experimental support for the accuracy of the Ni XII line ratio calculations, and hence for the atomic data adopted in their derivation

    The effect of organic management on soil quality indicators

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    This report was presented at the UK Organic Research 2002 Conference. A range of physical, biological and chemical parameters were measured in organic soil that had been managed in different ways and in a conventional control. Factors were identified that could be used to construct an index of soil quality

    LCDG4 and DigiSim - Simulation activities at NICADD/NIU

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    We present two software packages developed to support detector R&D studies for the International Linear Collider. LCDG4 is a full-detector simulator that provides energy deposits from particles traversing the sensitive volumes of the detector. It has been extensively used within the American ILC community, providing data for algorithm development and detector optimization studies. DigiSim models real-life digitization effects, converting the idealized response into simulated detector readout. It has many useful features to improve the realism in modeling detector response. The main characteristics of these two complementary packages are discussed.Comment: 8 pages, 7 figures, submitted to LCWS05 conference proceedings. Uses slac_one.rt

    Heavy Metals Accumulation by Indigenous Plants Growing in Contaminated Soil in a Gold Mining Area in Ghana

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    Phytoremediation is an environmentally friendly, low cost biotechnological process that is fast gaining prominence in the cleaning of contaminated soils in the tropics. The accumulative potential of indigenous or native plants for heavy metals in mine tailings at the Storage Facility of the Chirano Gold Mine Limited, Ghana was investigated. Plant species were sampled in five plots, each 32 m2. Samples of plants were harvested and separated into roots and shoots and the corresponding rhizospheric soil samples collected. They were analysed for the total concentrations of heavy metals; Arsenic (As), Cadmium (Cd) and Zinc (Zn) using Atomic Absorption Spectrophotometer. Bioavailable fractions of studied metals in the soil samples were determined with the formation of metal complex with Ethylenediaminetetraacetic acid and ammonium acetate reagents. The hyper-accumulation potential and mobility of heavy metals within the plants were determined from the bioaccumulation and translocation factors. Differences in mean concentrations of heavy metals in the plants (shoot, root and whole) were separated using Tukey B Analysis of Variance, SPSS version 20, at significant level of p &lt; 0.05. The mean concentrations of total and bioavailable As, Cd, and Zn in the soil samples varied with Zinc being most predominant (13.20 mg/kg). However, As was the most available with 39% bioavailability. The soil elemental concentrations of As (3.0 mg/kg), Cd (0.29 mg/kg) and Zn (13.20 mg/kg) were below the WHO recommended standards of 12 mg/kg, 1.4 mg/kg and 200 mg/kg for As, Cd and Zn respectively. The concentrations of all metals in the plant organs varied between species. In all plant species Zinc was the most accumulated heavy metal, recording the highest level of accumulation (135.76 mg/kg) in the root of Euphorbia heterophylla. Bioaccumulation factor as expressed by total and bioavailable metal concentrations in soil indicate that all the plant species demonstrate good hyperaccumulation and phytostabilisation potential for Zn and Cd whilst 13 and 8 plant species demonstrate good phytoextraction potential for As. The translocation factor indicate that 8 plant species are good phytostabilisers for Zn, 7 plant species for Cd and 10 plant species for As. The accumulative and phytostabilisation potential of these plant species provide useful information about their selective exploitation for effective phytoremediation of the tailings dam at Chirano Gold Mine. Keywords: phytoremediation, heavy metal, hyperaccumulation, phytostabilisation, indigenous plants, bioavailable
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