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Showing 1 to 20 of 871 for “"abundances"”.
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Nitrogen Abundances in Early-Type Be Stars
… are analyzed for their photospheric nitrogen abundances in an effort to detect rotational mixing in the Be stars. Be stars are massive stars, between 3 and 20 times the mass of the Sun, that are surrounded by a thin, equatorial disk of gas that produces emission lines in their optical and …
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Dynamic Spatial Forecasting of Sea Lice Abundances
Sea lice, Lepeophtheirus salmonis, are a major challenge to both aquaculture and wild salmon populations. L. salmonis infect salmonids, feeding on mucous, skin and flesh of infected fish, reducing fitness and increasing morbidity. The management of sea lice is a key consideration for farm operators …
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Chemical abundances in planetary nebulae in NGG 6822
… in the XX37 - XX71 spectral ranges, the relative abundances of He, N, , Ne, S are calculated with respect to H (Log (H) = 12.) for each nebula. Electron densities are derived for the planetary nebulae from the ratio of the Cs IlU line intensities, I(6716)/I(6731), while their temperatures are …
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Trend Analyses of the Abundances of Atmospheric Molecules
… caused a dramatic increase in their atmospheric abundances. Although these HFCs do not contribute directly to the depletion of the ozone layer because they contain no chlorine, they are powerful greenhouse gases with large global warming potentials. In January 2019, the Kigali Amendment to the …
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Exploring the Enstatite Chondrites: Modal Abundances, Metamorphic History, and Volatile Challenges
… 1 presents a comparative analysis of mineral abundances using automated point counting, X-ray diffraction analysis, and XMapTools-based phase mapping. The results reveal significant variations in silicate and sulfide abundances across EC groups, challenging the conventional binary …
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Spectroscopic abundances of solar-type dwarfs in open cluster M34 (Ngc 1039)
Parameters and relative abundances of Fe, Ni, Ti, Cr, Ca, Si, Al, and Mg have been derived for nine M34 G and K dwarfs from high-resolution, modest S/N, Keck/HIRES spectra. Effective temperatures have been derived spectroscopically and fall in the range 4750 ≤ Teff ≤ 6130 K. Despite modest …
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The evolution of isotoipc abundances from high-redshift to the local universe
Recent observations of carbon, sulphur, and titanium isotopes at redshifts z-.1 and in the Galactic stellar disc and halo have opened a new window into the study of isotopic abundance patterns and the origin of the chemical elements. Using our Galactic chemical evolution code CEtool, we have …
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Photoionization of Se Ions for the Determination of Elemental Abundances in Astrophysical Nebulae
Absolute single photoionization cross section measurements are presented for Se+ ,Se2+, Se3+ and Se5+. These measurements were performed at undulator beamline 10.0.1 of the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory using the merged-beams technique. All ions except Se5+ …
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Natural variations in strontium isotope abundances in minerals: a possible geologic age method
Thesis. (Ph.D.) Massachusetts Institute of Technology. Dept. of Geology, 1952.
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Effects of prescribed fire on breeding forest songbird abundances in central and Southern Illinois
… frequency, time-since-fire) on breeding bird abundances and probabilities of occurrence. I also included landscape variables (i.e., proportion forest cover, distance to forest edge) in analyses, as well as data from points where no prescribed fire had occurred. I chose to focus on 10 …
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The abundances and distribution of some trace elements in some selected South African shales
This thesis is the study of a single farm, Klaver Valley in the Darling district, 1812 - 1898. Chapter One provides a physical view of Klaver Valley from 1812 to 1898 showing the changes in the landscape and production of grains, wine and wool over the period. It argues that these changes occurred …
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Sr87/Sr86 ratios, K/Rb ratios, and rare-earth element abundances in pyroxene granulites.
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Sciences, 1969.
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Multiple-Species Models for True Abundances Allowing for Heterogeneity of Capture Between and Within Species
… Previous research involving multiple species' abundances have largely ignored this fact. In this paper, we explore the use of finite mixture modeling to quantify species' true abundances within a population while allowing for unknown differences in the individuals' capture probabilities. This …
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Design and evaluation of a laser ion source for TITAN to measure 222Rn daughter product abundances
This research focuses on developing and implementing a Laser Ion Source (LIS) at TRIUMF’s Ion Trap for Atomic and Nuclear Science (TITAN) facility to achieve high-precision isotope abundance ratio mea-surements across diverse materials. The project aims to quantify long-lived daughter products of …
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Mass spectrometric determination of the relative isotope abundances of calcium and the determination of geologic age
Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Geology, 1956.
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Effects of ash from native and alien plants on phytoplankton biomass and mosquito abundances: A mesocosm experiment
… dynamics and (ii) post–colonization mosquito abundances using six plant species [i.e., three natives (apple leaf Philenoptera violacea, Transvaal milk plum Englerophytum magalismontanum, quinine tree Rauvolfia caffra) and three aliens (lantana Lantana camara, gum Eucalyptus camaldulensis, …
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