NEON AND OXYGEN ABUNDANCES AND ABUNDANCE RATIO IN THE SOLAR CORONA
DOE Office of Scientific and Technical Information (OSTI.GOV)
Landi, E.; Testa, P., E-mail: elandi@umich.edu
2015-02-20
In this work we determine the Ne/O abundance ratio from Solar and Heliospheric Observatory (SOHO)/Solar Ultraviolet Measurement of Emitted Radiation (SUMER) off-disk observations of quiescent streamers over the 1996-2008 period. We find that the Ne/O ratio is approximately constant over solar cycle 23 from 1996 to 2005, at a value of 0.099 ± 0.017; this value is lower than the transition region determinations from the quiet Sun used to infer the neon photospheric abundance from the oxygen photospheric abundance. Also, the Ne/O ratio we determined from SUMER is in excellent agreement with in situ determinations from ACE/SWICS. In 2005-2008, the Ne/O abundancemore » ratio increased with time and reached 0.25 ± 0.05, following the same trend found in the slowest wind analyzed by ACE/SWICS. Further, we measure the absolute abundance in the corona for both oxygen and neon from the data set of 1996 November 22, obtaining A {sub o} = 8.99 ± 0.04 and A {sub Ne} = 7.92 ± 0.03, and we find that both elements are affected by the first ionization potential (FIP) effect, with oxygen being enhanced by a factor of 1.4-2.1 over its photospheric abundance, and neon being changed by a factor of 0.75-1.20. We conclude that the Ne/O ratio is not constant in the solar atmosphere, both in time and at different heights, and that it cannot be reliably used to infer the neon abundance in the photosphere. Also, we argue that the FIP effect was less effective during the minimum of solar cycle 24, and that the Ne/O = 0.25 ± 0.05 value measured at that time is closer to the true photospheric value, leading to a neon photospheric abundance larger than assumed by ≈40%. We discuss the implications of these results for the solar abundance problem, for the FIP effect, and for the identification of the source regions of the solar wind.« less
Abundance ratios in dwarf elliptical galaxies
NASA Astrophysics Data System (ADS)
Şen, Ş.; Peletier, R. F.; Boselli, A.; den Brok, M.; Falcón-Barroso, J.; Hensler, G.; Janz, J.; Laurikainen, E.; Lisker, T.; Mentz, J. J.; Paudel, S.; Salo, H.; Sybilska, A.; Toloba, E.; van de Ven, G.; Vazdekis, A.; Yesilyaprak, C.
2018-04-01
We determine abundance ratios of 37 dwarf ellipticals (dEs) in the nearby Virgo cluster. This sample is representative of the early-type population of galaxies in the absolute magnitude range -19.0 < Mr < -16.0. We analyse their absorption line-strength indices by means of index-index diagrams and scaling relations and use the stellar population models to interpret them. We present ages, metallicities, and abundance ratios obtained from these dEs within an aperture size of Re/8. We calculate [Na/Fe] from NaD, [Ca/Fe] from Ca4227, and [Mg/Fe] from Mgb. We find that [Na/Fe] is underabundant with respect to solar, whereas [Mg/Fe] is around solar. This is exactly opposite to what is found for giant ellipticals, but follows the trend with metallicity found previously for the Fornax dwarf NGC 1396. We discuss possible formation scenarios that can result in such elemental abundance patterns, and we speculate that dEs have disc-like star formation history (SFH) favouring them to originate from late-type dwarfs or small spirals. Na-yields appear to be very metal-dependent, in agreement with studies of giant ellipticals, probably due to the large dependence on the neutron-excess in stars. We conclude that dEs have undergone a considerable amount of chemical evolution, they are therefore not uniformly old, but have extended SFH, similar to many of the Local Group galaxies.
RELATIVE ABUNDANCE MEASUREMENTS IN PLUMES AND INTERPLUMES
DOE Office of Scientific and Technical Information (OSTI.GOV)
Guennou, C.; Hahn, M.; Savin, D. W., E-mail: cguennou@iac.es
2015-07-10
We present measurements of relative elemental abundances in plumes and interplumes. Plumes are bright, narrow structures in coronal holes that extend along open magnetic field lines far out into the corona. Previous work has found that in some coronal structures the abundances of elements with a low first ionization potential (FIP) <10 eV are enhanced relative to their photospheric abundances. This coronal-to-photospheric abundance ratio, commonly called the FIP bias, is typically 1 for elements with a high-FIP (>10 eV). We have used Extreme Ultraviolet Imaging Spectrometer observations made on 2007 March 13 and 14 over a ≈24 hr period tomore » characterize abundance variations in plumes and interplumes. To assess their elemental composition, we used a differential emission measure analysis, which accounts for the thermal structure of the observed plasma. We used lines from ions of iron, silicon, and sulfur. From these we estimated the ratio of the iron and silicon FIP bias relative to that for sulfur. From the results, we have created FIP-bias-ratio maps. We find that the FIP-bias ratio is sometimes higher in plumes than in interplumes and that this enhancement can be time dependent. These results may help to identify whether plumes or interplumes contribute to the fast solar wind observed in situ and may also provide constraints on the formation and heating mechanisms of plumes.« less
Abundance ratios of oxygen, neon, and magnesium in solar active regions and flares: The FIP effect
NASA Technical Reports Server (NTRS)
Widing, K. G.; Feldman, U.
1995-01-01
Relative abundances of oxygen, neon, and magnesium have been derived for a sample of nine solar active regions, flares, and an erupting prominance by combining plots of the ion differential emission measures. The observations were photographed in the 300-600 A range by the Naval Research Laboratory (NRL) spectroheliograph on Skylab. Methods for deriving the Mg/Ne abundance ratio-which measures the separation between the low- first ionization potential (FIP) and high-FIP abundnace plateaus-have been described in previous papers. In this paper we describe the spectroscopic methods for deriving the O/Ne abundance ratio, which gives the ratio between two high-FIP elements. The plot of the O/Ne ratio versus the Mg/Ne ratio in the sample of nine Skylab events is shown. The variation in the Mg/Ne ratio by a factor of 6 is associated with a much smaller range in the O/Ne ratio. This is broadly consistent with the presence of the standard FIP pattern of abundances in the outer atmosphere of the Sun. However, a real change in the relative abundances of oxygen and neon by a factor of 1.5 cannot be excluded.
Element Abundance Ratios in the Quiet Sun Transition Region
NASA Astrophysics Data System (ADS)
Young, P. R.
2018-03-01
Element abundance ratios of magnesium to neon (Mg/Ne) and neon to oxygen (Ne/O) in the transition region of the quiet Sun have been derived by re-assessing previously published data from the Coronal Diagnostic Spectrometer on board the Solar and Heliospheric Observatory in the light of new atomic data. The quiet Sun Mg/Ne ratio is important for assessing the effect of magnetic activity on the mechanism of the first ionization potential (FIP) effect, while the Ne/O ratio can be used to infer the solar photospheric abundance of neon, which cannot be measured directly. The average Mg/Ne ratio is found to be 0.52 ± 0.11, which applies over the temperature region 0.2–0.7 MK, and is consistent with the earlier study. The Ne/O ratio is, however, about 40% larger, taking the value 0.24 ± 0.05 that applies to the temperature range 0.08–0.40 MK. The increase is mostly due to changes in ionization and recombination rates that affect the equilibrium ionization balance. If the Ne/O ratio is interpreted as reflecting the photospheric ratio, then the photospheric neon abundance is 8.08 ± 0.09 or 8.15 ± 0.10 (on a logarithmic scale for which hydrogen is 12), according to whether the oxygen abundances of M. Asplund et al. or E. Caffau et al. are used. The updated photospheric neon abundance implies a Mg/Ne FIP bias for the quiet Sun of 1.6 ± 0.6.
STATISTICAL CHARACTERISTICS OF ELEMENTAL ABUNDANCE RATIOS: OBSERVATIONS FROM THE ACE SPACECRAFT
DOE Office of Scientific and Technical Information (OSTI.GOV)
Zhao, L.-L.; Zhang, H.
We statistically analyze the elemental galactic cosmic ray (GCR) composition measurements of elements 5 ≤ Z ≤ 28 within the energy range 30–500 MeV/nucleon from the CRIS instrument on board the ACE spacecraft in orbit about the L1 Lagrange point during the period from 1997 to 2014. Similarly to the last unusual solar minimum, the elevated elemental intensities of all heavy nuclei during the current weak solar maximum in 2014 are ∼40% higher than that of the previous solar maximum in 2002, which has been attributed to the weak modulation associated with low solar activity levels during the ongoing weakestmore » solar maximum since the dawn of space age. In addition, the abundance ratios of heavy nuclei with respect to elemental oxygen are generally independent of kinetic energy per nucleon in the energy region 60–200 MeV/nuc, in good agreement with previous experiments. Furthermore, the abundance ratios of most relatively abundant species, except carbon, exhibit considerable solar-cycle variation, which are obviously positively correlated with the sunspot numbers with about one-year time lag. We also find that the percentage variation of abundance ratios for most elements are approximately identical. These preliminary results provide valuable insights into the characteristics of elemental heavy nuclei composition and place new and significant constraints on future GCR heavy nuclei propagation and modulation models.« less
Exploring the 13CO/C18O abundance ratio towards Galactic young stellar objects and HII regions
NASA Astrophysics Data System (ADS)
Areal, M. B.; Paron, S.; Celis Peña, M.; Ortega, M. E.
2018-05-01
Aims: Determining molecular abundance ratios is important not only for the study of Galactic chemistry, but also because they are useful to estimate physical parameters in a large variety of interstellar medium environments. One of the most important molecules for tracing the molecular gas in the interstellar medium is CO, and the 13CO/C18O abundance ratio is usually used to estimate molecular masses and densities of regions with moderate to high densities. Nowadays isotope ratios are in general indirectly derived from elemental abundances ratios. We present the first 13CO/C18O abundance ratio study performed from CO isotope observations towards a large sample of Galactic sources of different natures at different locations. Methods: To study the 13CO/C18O abundance ratio, we used 12CO J = 3 - 2 data obtained from the CO High-Resolution Survey, 13CO and C18O J = 3 - 2 data from the 13CO/C18O (J = 3 - 2) Heterodyne Inner Milky Way Plane Survey, and some complementary data extracted from the James Clerk Maxwell Telescope database. We analyzed a sample of 198 sources composed of young stellar objects (YSOs), and HII and diffuse HII regions as catalogued in the Red MSX Source Survey in 27.°5 ≤ l ≤ 46.°5 and |b|0.°5. Results: Most of the analyzed sources are located in the galactocentric distance range 4.0-6.5 kpc. We found that YSOs have, on average, lower 13CO/C18O abundance ratios than HII and diffuse HII regions. Taking into account that the gas associated with YSOs should be less affected by the radiation than in the case of the others sources, selective far-UV photodissociation of C18O is confirmed. The 13CO/C18O abundance ratios obtained in this work are systematically lower than those predicted from the known elemental abundance relations. These results will be useful in future studies of molecular gas related to YSOs and HII regions based on the observation of these isotopes.
The relative abundance of neon and magnesium in the solar corona
NASA Technical Reports Server (NTRS)
Rugge, H. R.; Walker, A. B. C., Jr.
1976-01-01
A technique is proposed for specifically determining the relative solar coronal abundance of neon and magnesium. The relative abundance is calculated directly from the relative intensity of the resonance lines of Ne X (12.134A) and Mg XI (9.169A) without the need for the development of a detailed model of the thermal structure of the corona. Moderate resolution Bragg crystal spectrometer results from the OVI-10 satellite were used to determine a coronal neon to magnesium relative abundance of 1.47 + or - 0.38. The application of this technique to a recent higher resolution rocket observation gave an abundance ratio of approximately 0.93 + or - 0.15.
Molecular abundances and C/O ratios in chemically evolving planet-forming disk midplanes
NASA Astrophysics Data System (ADS)
Eistrup, Christian; Walsh, Catherine; van Dishoeck, Ewine F.
2018-05-01
Context. Exoplanet atmospheres are thought be built up from accretion of gas as well as pebbles and planetesimals in the midplanes of planet-forming disks. The chemical composition of this material is usually assumed to be unchanged during the disk lifetime. However, chemistry can alter the relative abundances of molecules in this planet-building material. Aims: We aim to assess the impact of disk chemistry during the era of planet formation. This is done by investigating the chemical changes to volatile gases and ices in a protoplanetary disk midplane out to 30 AU for up to 7 Myr, considering a variety of different conditions, including a physical midplane structure that is evolving in time, and also considering two disks with different masses. Methods: An extensive kinetic chemistry gas-grain reaction network was utilised to evolve the abundances of chemical species over time. Two disk midplane ionisation levels (low and high) were explored, as well as two different makeups of the initial abundances ("inheritance" or "reset"). Results: Given a high level of ionisation, chemical evolution in protoplanetary disk midplanes becomes significant after a few times 105 yr, and is still ongoing by 7 Myr between the H2O and the O2 icelines. Inside the H2O iceline, and in the outer, colder regions of the disk midplane outside the O2 iceline, the relative abundances of the species reach (close to) steady state by 7 Myr. Importantly, the changes in the abundances of the major elemental carbon and oxygen-bearing molecules imply that the traditional "stepfunction" for the C/O ratios in gas and ice in the disk midplane (as defined by sharp changes at icelines of H2O, CO2 and CO) evolves over time, and cannot be assumed fixed, with the C/O ratio in the gas even becoming smaller than the C/O ratio in the ice. In addition, at lower temperatures (<29 K), gaseous CO colliding with the grains gets converted into CO2 and other more complex ices, lowering the CO gas abundance between
NASA Astrophysics Data System (ADS)
Yamagishi, M.; Kaneda, H.; Ishihara, D.; Oyabu, S.; Onaka, T.; Shimonishi, T.; Suzuki, T.
2015-07-01
We report CO2/H2O ice abundance ratios in seven nearby star-forming galaxies based on the AKARI near-infrared (2.5-5.0 μm) spectra. The CO2/H2O ice abundance ratios show clear variations between 0.05 and 0.2 with the averaged value of 0.14 ± 0.01. The previous study on M82 revealed that the CO2/H2O ice abundance ratios strongly correlate with the intensity ratios of the hydrogen recombination Brα line to the polycyclic aromatic hydrocarbon (PAH) 3.3 μm feature. In the present study, however, we find no correlation for the seven galaxies as a whole due to systematic differences in the relation between CO2/H2O ice abundance and Brα/PAH 3.3 μm intensity ratios from galaxy to galaxy. This result suggests that there is another parameter that determines the CO2/H2O ice abundance ratios in a galaxy in addition to the Brα/PAH 3.3 μm ratios. We find that the CO2/H2O ice abundance ratios positively correlate with the specific star formation rates of the galaxies. From these results, we conclude that CO2/H2O ice abundance ratios tend to be high in young star-forming galaxies.
Raman scattering method and apparatus for measuring isotope ratios and isotopic abundances
Harney, Robert C.; Bloom, Stewart D.
1978-01-01
Raman scattering is used to measure isotope ratios and/or isotopic abundances. A beam of quasi-monochromatic photons is directed onto the sample to be analyzed, and the resulting Raman-scattered photons are detected and counted for each isotopic species of interest. These photon counts are treated mathematically to yield the desired isotope ratios or isotopic abundances.
On the Measurement of Elemental Abundance Ratios in Inner Galaxy H II Regions
NASA Technical Reports Server (NTRS)
Simpson, Janet P.; Rubin, Robert H.; Colgan, Sean W. J.; Erickson, Edwin F.; Haas, Michael R.
2004-01-01
unseen ionization states. We find, with large uncertainties, that oxygen does not, have a high abundance, with the result that the N/O ratio is as high (approx. 0.35) as previously reported. The reasons for the uncertainty in the ionization corrections for oxygen are both the non-uniqueness of the H II region models and the sensitivity of these models to different input atomic data and stellar atmosphere models. We discuss these predictions and conclude that only a few of the latest models adequately reproduce H II region observations, including the well-known, relatively-large observed Ne++/O++ ratios in low- and moderate-excitation H II regions.
Determination of nitrogen to carbon abundance ratios from transition layer emission lines
NASA Technical Reports Server (NTRS)
Boehm-Vitense, Erika
1992-01-01
We have finished studying the nitrogen to carbon abundance ratios for stars with different effective temperatures T(sub eff) and luminosities using transition layer emission lines and using spectra available in the IUE archives. The N/C abundance ratio determinations using transition layer emission lines are as accurate as the photospheric abundance determinations as found by comparison of results obtained by both methods for the same stars. Our measurements confirm photospheric abundance determinations in regions of the HR diagram where they can be obtained. Our studies have extended the temperature range to higher temperatures. They have shown the exact positions in the HR diagram where the mixing due to the outer convection zones reaches deep enough to bring nuclear processed material to the surface. This occurs at effective temperatures which are higher by delta log T(sub eff) approximately 0.04 or roughly 400 K than expected theoretically. Since the depth of the convection zone increases rapidly with decreasing T(sub eff) this may indicate considerable overshoot beyond the lower boundary of the convection zone. Our N/C abundance ratio determinations from transition layer emission lines have confirmed that the actual enrichment observed for some cool giants is larger than expected theoretically, again indicating a larger degree of mixing in several stars either from below or from above. For the supergiants it probably indicates overshoot above the convective core in the progenitor main sequence stars. For the more massive giants this may also be the case, though we did not find a correlation between delta log N/C and the absolute magnitudes, but these are rather uncertain. As byproducts of these studies we also found anomalies in Si/C and N/C abundance ratios for F giants which can be understood as the relict of surface abundance changes for their main sequence progenitors due to diffusion. This anomaly disappears for G giants, for which the depths of the
DOE Office of Scientific and Technical Information (OSTI.GOV)
Yamagishi, M.; Kaneda, H.; Ishihara, D.
2015-07-01
We report CO{sub 2}/H{sub 2}O ice abundance ratios in seven nearby star-forming galaxies based on the AKARI near-infrared (2.5–5.0 μm) spectra. The CO{sub 2}/H{sub 2}O ice abundance ratios show clear variations between 0.05 and 0.2 with the averaged value of 0.14 ± 0.01. The previous study on M82 revealed that the CO{sub 2}/H{sub 2}O ice abundance ratios strongly correlate with the intensity ratios of the hydrogen recombination Brα line to the polycyclic aromatic hydrocarbon (PAH) 3.3 μm feature. In the present study, however, we find no correlation for the seven galaxies as a whole due to systematic differences in themore » relation between CO{sub 2}/H{sub 2}O ice abundance and Brα/PAH 3.3 μm intensity ratios from galaxy to galaxy. This result suggests that there is another parameter that determines the CO{sub 2}/H{sub 2}O ice abundance ratios in a galaxy in addition to the Brα/PAH 3.3 μm ratios. We find that the CO{sub 2}/H{sub 2}O ice abundance ratios positively correlate with the specific star formation rates of the galaxies. From these results, we conclude that CO{sub 2}/H{sub 2}O ice abundance ratios tend to be high in young star-forming galaxies.« less
Alejo-Plata, Carmen; Gómez, José Luis; Serrano-Guzmán, Saúl J
2014-06-01
Variability in the relative abundance, size structure and sex ratio of the dolphinfish Coryphaena hippurus (Pisces: Coryphaenidae) in the Gulf of Tehuantepec, México. The dolphinfish (Coryphaena hippurus), is an oceanic epipelagic fish found worldwide in tropical and subtropical waters, with a high dispersal capability via large-scale migrations. This fast-swimming top-level predator is abundant in the Gulf of Tehuantepec, where it is caught incidentally by artisanal fisheries, and represents a target species for both recreational and commercial fisheries in Mexico, Ecuador, Peru and Central America. Nowadays, local fishery information on this species is scarce, thus our objective was to analyze the size structure by sex and the catch-per-unit-effort (CPUE) tendency of dolphinfish caught in the Gulf of Tehuantepec, from 2000 to 2007. For this, fishery catches information was obtained from the artisanal fleet, at six landing sites in the Gulf, and the sex ratio, fork length (FL) and the catch per unit effort (CPUE) were estimated. From all sampling sites, a total of 3 494 females, and 3 877 males were obtained, and dolphinfish size as fork length (FL) ranged from 20.5 to 152cm. Fish size ranged from 25.5 to 148cm furcal length (FL) in males, and 20.5 to 129cm FL in females. The sex ratio (males:females) was 1:1, except in April-May (1:1.5, p < 0.05) and November (1:0.5, p < 0.05). The sex ratio at different size classes showed a significant bias towards females at smaller sizes (< 75cm FL), whereas the males were predominant in larger size classes (> 100cm FL). The size structure was bimodal, with a variation in the size average; the modes were defined as the small group (FL = 50-55cm) and the large size group (FL = 100-110cm). The CPUE showed seasonal changes: values were high for the November-December period, and values were lower for July-August. The seasonal and inter annual variation in the abundance of dolphinfish is probably related to a pre
Casula, P.; Nichols, J.D.
2003-01-01
When capturing and marking of individuals is possible, the application of newly developed capture-recapture models can remove several sources of bias in the estimation of population parameters such as local abundance and sex ratio. For example, observation of distorted sex ratios in counts or captures can reflect either different abundances of the sexes or different sex-specific capture probabilities, and capture-recapture models can help distinguish between these two possibilities. Robust design models and a model selection procedure based on information-theoretic methods were applied to study the local population structure of the endemic Sardinian chalk hill blue butterfly, Polyommatus coridon gennargenti. Seasonal variations of abundance, plus daily and weather-related variations of active populations of males and females were investigated. Evidence was found of protandry and male pioneering of the breeding space. Temporary emigration probability, which describes the proportion of the population not exposed to capture (e.g. absent from the study area) during the sampling process, was estimated, differed between sexes, and was related to temperature, a factor known to influence animal activity. The correlation between temporary emigration and average daily temperature suggested interpreting temporary emigration as inactivity of animals. Robust design models were used successfully to provide a detailed description of the population structure and activity in this butterfly and are recommended for studies of local abundance and animal activity in the field.
What is Neptune's D/H ratio really telling us about its water abundance?
NASA Astrophysics Data System (ADS)
Ali-Dib, Mohamad; Lakhlani, Gunjan
2018-05-01
We investigate the deep-water abundance of Neptune using a simple two-component (core + envelope) toy model. The free parameters of the model are the total mass of heavy elements in the planet (Z), the mass fraction of Z in the envelope (fenv), and the D/H ratio of the accreted building blocks (D/Hbuild).We systematically search the allowed parameter space on a grid and constrain it using Neptune's bulk carbon abundance, D/H ratio, and interior structure models. Assuming solar C/O ratio and cometary D/H for the accreted building blocks are forming the planet, we can fit all of the constraints if less than ˜15 per cent of Z is in the envelope (f_{env}^{median} ˜ 7 per cent), and the rest is locked in a solid core. This model predicts a maximum bulk oxygen abundance in Neptune of 65× solar value. If we assume a C/O of 0.17, corresponding to clathrate-hydrates building blocks, we predict a maximum oxygen abundance of 200× solar value with a median value of ˜140. Thus, both cases lead to oxygen abundance significantly lower than the preferred value of Cavalié et al. (˜540× solar), inferred from model-dependent deep CO observations. Such high-water abundances are excluded by our simple but robust model. We attribute this discrepancy to our imperfect understanding of either the interior structure of Neptune or the chemistry of the primordial protosolar nebula.
THE HCN/HNC ABUNDANCE RATIO TOWARD DIFFERENT EVOLUTIONARY PHASES OF MASSIVE STAR FORMATION
DOE Office of Scientific and Technical Information (OSTI.GOV)
Jin, Mihwa; Lee, Jeong-Eun; Kim, Kee-Tae, E-mail: mihwajin.sf@gmail.com, E-mail: jeongeun.lee@khu.ac.kr, E-mail: ktkim@kasi.re.kr
2015-07-20
Using the H{sup 13}CN and HN{sup 13}C J = 1–0 line observations, the abundance ratio of HCN/HNC has been estimated for different evolutionary stages of massive star formation: infrared dark clouds (IRDCs), high-mass protostellar objects (HMPOs), and ultracompact H ii regions (UCH iis). IRDCs were divided into “quiescent IRDC cores (qIRDCc)” and “active IRDC cores (aIRDCc),” depending on star formation activity. The HCN/HNC ratio is known to be higher at active and high temperature regions related to ongoing star formation, compared to cold and quiescent regions. Our observations toward 8 qIRDCc, 16 aIRDCc, 23 HMPOs, and 31 UCH iis showmore » consistent results; the ratio is 0.97 (±0.10), 2.65 (±0.88), 4.17 (±1.03), and 8.96 (±3.32) in these respective evolutionary stages, increasing from qIRDCc to UCH iis. The change of the HCN/HNC abundance ratio, therefore, seems directly associated with the evolutionary stages of star formation, which have different temperatures. One suggested explanation for this trend is the conversion of HNC to HCN, which occurs effectively at higher temperatures. To test the explanation, we performed a simple chemical model calculation. In order to fit the observed results, the energy barrier of the conversion must be much lower than the value provided by theoretical calculations.« less
DOE Office of Scientific and Technical Information (OSTI.GOV)
Doschek, G. A.; Warren, H. P.; Feldman, U.
2015-07-20
In determining the element abundance of argon (a high first ionization potential; FIP element) relative to calcium (a low FIP element) in flares, unexpectedly high intensities of two Ar xiv lines (194.40, 187.96 Å) relative to a Ca xiv line (193.87 Å) intensity were found in small (a few arcseconds) regions near sunspots in flare spectra recorded by the Extreme-ultraviolet Imaging Spectrometer on the Hinode spacecraft. In the most extreme case the Ar xiv line intensity relative to the Ca xiv intensity was 7 times the value expected from the photospheric abundance ratio, which is about 30 times the abundancemore » of argon relative to calcium in active regions, i.e., the measured Ar/Ca abundance ratio is about 10 instead of 0.37 as in active regions. The Ar xiv and Ca xiv lines are formed near 3.4 MK and have very similar contribution functions. This is the first observation of the inverse FIP effect in the Sun. Other regions show increases of 2–3 over photospheric abundances, or just photospheric abundances. This phenomenon appears to occur rarely and only over small areas of flares away from the regions containing multi-million degree plasma, but more work is needed to quantify the occurrences and their locations. In the bright hot regions of flares the Ar/Ca abundance ratio is coronal, i.e., the same as in active regions. In this Letter we show three examples of the inverse FIP effect.« less
H2CS abundances and ortho-to-para ratios in interstellar clouds
NASA Technical Reports Server (NTRS)
Minh, Y. C.; Irvine, W. M.; Brewer, M. K.
1991-01-01
Several H2CS ortho and para transitions have been observed toward interstellar molecular clouds, including cold, dark clouds and star-forming regions. H2CS fractional abundances f(H2CS) about 1-2 10 to the -9th relative to molecular hydrogen toward TMC-1, Orion A, and NGC 7538, and about 5 10 to the -10th for L134N are derived. The H2CS ortho-to-para ratios in TMC-1 are about 1.8 toward the cyanopolyyne peak and the ammonia peak, which may indicate the thermalization of H2CS on 10 K grains. A ratio of about 3, the statistical value, for Orion (3N, 1E) and NGC 7538 is derived, while a value of about 2 for Orion (KL) is found.
Calculations concerning the HCO(+)/HOC(+) abundance ratio in dense interstellar clouds
NASA Technical Reports Server (NTRS)
Defrees, D. J.; Mclean, A. D.; Herbst, E.
1984-01-01
Calculations have been performed to determine the rate coefficients of several reactions involved in both the formation and depletion of interstellar HCO(+) and HOC(+). The abundance of HOC(+) deduced from these calculations is consistent with the tentative identification of HOC(+) in Sgr B2 by Woods et al. (1983). The large HCO(+)/HOC(+) abundance ratio observed by Woods et al. is due at least in part to a more rapid formation rate for HCO(+) and probably due as well to a more rapid depletion rate for HOC(+).
Ionization ratios and elemental abundances in the atmosphere of 68 Tauri
NASA Astrophysics Data System (ADS)
Aouina, A.; Monier, R.
2017-12-01
We have derived the ionization ratios of twelve elements in the atmosphere of the star 68 Tauri (HD 27962) using an ATLAS9 model atmosphere with 72 layers computed for the effective temperature and surface gravity of the star. We then computed a grid of synthetic spectra generated by SYNSPEC49 based on an ATLAS9 model atmosphere in order to model one high resolution spectrum secured by one of us (RM) with the échelle spectrograph SOPHIE at Observatoire de Haute Provence. We could determine the abundances of several elements in their dominant ionization stage, including those defining the Am phenomenon. We thus provide new abundance determinations for 68 Tauri using updated accurate atomic data retrieved from the NIST database which extend previous abundance works.
Ion-molecule calculation of the abundance ratio of CCD to CCH in dense interstellar clouds
NASA Technical Reports Server (NTRS)
Herbst, Eric; Adams, Nigel G.; Smith, David; Defrees, D. J.
1987-01-01
Laboratory measurements and calculations have been performed to determine the abundance ratio of the deuterated ethynyl radical (CCD) to the normal radical (CCH) which can be achieved in dense interstellar clouds via isotopic fractionation in the C2H2(+) (HD)=C2HD(+)(H2) system of reactions. According to this limited treatment, the CCD/CCH abundance ratio which can be attained is in the range 0.02-0.03 for the Orion molecular cloud and 0.0l-0.02 for TMC-1. These ranges of numbers are in reasonable agreement with the observed values in Orion and TMC-1. However, the analysis of the CCD/CCH abundance ratio is complicated via the presence of competing fractionation mechanisms, especially in the low-temperature source TMC-1.
NASA Technical Reports Server (NTRS)
Falconer, David A.
1994-01-01
Intensities of EUV spectral lines were measured as a function of radius off the solar limb by two flights of Goddard's Solar EUV Rocket Telescope and Spectrograph (SERTS) for three quiet sun regions. The density scale height, line-ratio densities, line-ratio temperatures, and emission measures were determined. The line-ratio temperature determined from the ionization balances of Arnaud and Rothenflug (1985) were more self-consistent than the line-ratio temperatures obtained from the values of Arnaud and Raymond (1992). Limits on the filling factor were determined from the emission measure and the line-ratio densities for all three regions. The relative abundances of silicon, aluminum, and chromium to iron were determined. Results did agree with standard coronal relative elemental abundances for one observation, but did not agree for another. Aluminum was overabundant while silicon was underabundant. Heating was required above 1.15 solar radii for all three regions studied. For two regions, local nonconductive heating is needed for any filling factor, and in all three regions for filling factor of 0.1.
NASA Astrophysics Data System (ADS)
Mernier, F.; de Plaa, J.; Pinto, C.; Kaastra, J. S.; Kosec, P.; Zhang, Y.-Y.; Mao, J.; Werner, N.
2016-08-01
The hot intra-cluster medium (ICM) is rich in metals, which are synthesised by supernovae (SNe) explosions and accumulate over time into the deep gravitational potential well of clusters of galaxies. Since most of the elements visible in X-rays are formed by type Ia (SNIa) and/or core-collapse (SNcc) supernovae, measuring their abundances gives us direct information on the nucleosynthesis products of billions of SNe since the epoch of the star formation peak (z ~ 2-3). In this study, we use the EPIC and RGS instruments on board XMM-Newton to measure the abundances of nine elements (O, Ne, Mg, Si, S, Ar, Ca, Fe, and Ni) from a sample of 44 nearby cool-core galaxy clusters, groups, and elliptical galaxies. We find that the Fe abundance shows a large scatter (~20-40%) over the sample, within 0.2r500 and especially 0.05r500. Unlike the absolute Fe abundance, the abundance ratios (X/Fe) are uniform over the considered temperature range (~0.6-8 keV) and with a limited scatter. In addition to an unprecedented treatment of systematic uncertainties, we provide the most accurate abundance ratios measured so far in the ICM, including Cr/Fe and Mn/Fe which we firmly detected (>4σ with MOS and pn independently). We find that Cr/Fe, Mn/Fe, and Ni/Fe differ significantly from the proto-solar values. However, the large uncertainties in the proto-solar abundances prevent us from making a robust comparison between the local and the intra-cluster chemical enrichments. We also note that, interestingly, and despite the large net exposure time (~4.5 Ms) of our dataset, no line emission feature is seen around ~3.5 keV.
A reanalysis of the HCO(+)/HOC(+) abundance ratio in dense interstellar clouds
NASA Technical Reports Server (NTRS)
Jarrold, M. F.; Bowers, M. T.; Defrees, D. J.; Mclean, A. D.; Herbst, E.
1986-01-01
New theoretical and experimental results have prompted a reinvestigation of the HCO(+)/HOC(+) abundance ratio in dense interstellar clouds. These results pertain principally but not exclusively to the reaction between HOC(+) and H2, which was previously calculated by DeFrees et al. (1984) to possess a large activation energy barrier. New calculations, reported here, indicate that this activation energy barrier is quite small and may well be zero. In addition, experimental results at higher energy and temperature indicate strongly that the reaction proceeds efficiently at interstellar temperatures. If HOC(+) does indeed react efficiently with H2 in interstellar clouds, the calculated HCO(+)/HOC(+) abundance ratio rises to a substantially greater value under standard dense cloud conditions than is deduced via the tentative observation of HOC(+) in Sgr B2.
Solar abundance ratios of the iron-peak elements in the Perseus cluster.
2017-11-23
The metal abundance of the hot plasma that permeates galaxy clusters represents the accumulation of heavy elements produced by billions of supernovae. Therefore, X-ray spectroscopy of the intracluster medium provides an opportunity to investigate the nature of supernova explosions integrated over cosmic time. In particular, the abundance of the iron-peak elements (chromium, manganese, iron and nickel) is key to understanding how the progenitors of typical type Ia supernovae evolve and explode. Recent X-ray studies of the intracluster medium found that the abundance ratios of these elements differ substantially from those seen in the Sun, suggesting differences between the nature of type Ia supernovae in the clusters and in the Milky Way. However, because the K-shell transition lines of chromium and manganese are weak and those of iron and nickel are very close in photon energy, high-resolution spectroscopy is required for an accurate determination of the abundances of these elements. Here we report observations of the Perseus cluster, with statistically significant detections of the resonance emission from chromium, manganese and nickel. Our measurements, combined with the latest atomic models, reveal that these elements have near-solar abundance ratios with respect to iron, in contrast to previous claims. Comparison between our results and modern nucleosynthesis calculations disfavours the hypothesis that type Ia supernova progenitors are exclusively white dwarfs with masses well below the Chandrasekhar limit (about 1.4 times the mass of the Sun). The observed abundance pattern of the iron-peak elements can be explained by taking into account a combination of near- and sub-Chandrasekhar-mass type Ia supernova systems, adding to the mounting evidence that both progenitor types make a substantial contribution to cosmic chemical enrichment.
Solar abundance ratios of the iron-peak elements in the Perseus cluster
Aharonian, Felix; Akamatsu, Hiroki; Akimoto, Fumie; ...
2017-11-13
The metal abundance of the hot plasma that permeates galaxy clusters represents the accumulation of heavy elements produced by billions of supernovae1. Therefore, X-ray spectroscopy of the intracluster medium provides an opportunity to investigate the nature of supernova explosions integrated over cosmic time. In particular, the abundance of the iron-peak elements (chromium, manganese, iron and nickel) is key to understanding how the progenitors of typical type Ia supernovae evolve and explode2–6. Recent X-ray studies of the intracluster medium found that the abundance ratios of these elements differ substantially from those seen in the Sun, suggesting differences between the nature ofmore » type Ia supernovae in the clusters and in the Milky Way. However, because the K-shell transition lines of chromium and manganese are weak and those of iron and nickel are very close in photon energy, highresolution spectroscopy is required for an accurate determination of the abundances of these elements. Here in this paper we report observations of the Perseus cluster, with statistically significant detections of the resonance emission from chromium, manganese and nickel. Our measurements, combined with the latest atomic models, reveal that these elements have near-solar abundance ratios with respect to iron, in contrast to previous claims. Comparison between our results and modern nucleosynthesis calculations disfavours the hypothesis that type Ia supernova progenitors are exclusively white dwarfs with masses well below the Chandrasekhar limit (about 1.4 times the mass of the Sun). The observed abundance pattern of the iron-peak elements can be explained by taking into account a combination of near- and sub-Chandrasekhar-mass type Ia supernova systems, adding to the mounting evidence that both progenitor types make a substantial contribution to cosmic chemical enrichment.« less
Solar abundance ratios of the iron-peak elements in the Perseus cluster
DOE Office of Scientific and Technical Information (OSTI.GOV)
Aharonian, Felix; Akamatsu, Hiroki; Akimoto, Fumie
The metal abundance of the hot plasma that permeates galaxy clusters represents the accumulation of heavy elements produced by billions of supernovae1. Therefore, X-ray spectroscopy of the intracluster medium provides an opportunity to investigate the nature of supernova explosions integrated over cosmic time. In particular, the abundance of the iron-peak elements (chromium, manganese, iron and nickel) is key to understanding how the progenitors of typical type Ia supernovae evolve and explode2–6. Recent X-ray studies of the intracluster medium found that the abundance ratios of these elements differ substantially from those seen in the Sun, suggesting differences between the nature ofmore » type Ia supernovae in the clusters and in the Milky Way. However, because the K-shell transition lines of chromium and manganese are weak and those of iron and nickel are very close in photon energy, highresolution spectroscopy is required for an accurate determination of the abundances of these elements. Here in this paper we report observations of the Perseus cluster, with statistically significant detections of the resonance emission from chromium, manganese and nickel. Our measurements, combined with the latest atomic models, reveal that these elements have near-solar abundance ratios with respect to iron, in contrast to previous claims. Comparison between our results and modern nucleosynthesis calculations disfavours the hypothesis that type Ia supernova progenitors are exclusively white dwarfs with masses well below the Chandrasekhar limit (about 1.4 times the mass of the Sun). The observed abundance pattern of the iron-peak elements can be explained by taking into account a combination of near- and sub-Chandrasekhar-mass type Ia supernova systems, adding to the mounting evidence that both progenitor types make a substantial contribution to cosmic chemical enrichment.« less
Central Elemental Abundance Ratios In the Perseus Cluster: Resonant Scattering or SN Ia Enrichment?
NASA Technical Reports Server (NTRS)
Dupke, Renato A.; Arnaud, Keith; White, Nicholas E. (Technical Monitor)
2001-01-01
We have determined abundance ratios in the core of the Perseus Cluster for several elements. These ratios indicate a central dominance of Type 1a supernova (SN Ia) ejects similar to that found for A496, A2199 and A3571. Simultaneous analysis of ASCA spectra from SIS1, GIS2, and GIS3 shows that the ratio of Ni to Fe abundances is approx. 3.4 +/- 1.1 times solar within the central 4'. This ratio is consistent with (and more precise than) that observed in other clusters whose central regions are dominated by SN Ia ejecta. Such a large Ni overabundance is predicted by "convective deflagration" explosion models for SNe Ia such as W7 but is inconsistent with delayed detonation models. We note that with current instrumentation the Ni K(alpha) line is confused with Fe K(beta) and that the Ni overabundance we observe has been interpreted by others as an anomalously large ratio of Fe K(beta) to Fe K(alpha) caused by resonant scattering in the Fe K(alpha) line. We argue that a central enhancement of SN Ia ejecta and hence a high ratio of Ni to Fe abundances are naturally explained by scenarios that include the generation of chemical gradients by suppressed SN Ia winds or ram pressure stripping of cluster galaxies. It is not necessary to suppose that the intracluster gas is optically thick to resonant scattering of the Fe K(alpha) line.
Histogrammatic Method for Determining Relative Abundance of Input Gas Pulse
NASA Technical Reports Server (NTRS)
Mandrake, Lukas; Bornstein, Benjamin J.; Madzunkov, Stojan; MacAskill, John A.
2012-01-01
To satisfy the Major Constituents Analysis (MCA) requirements for the Vehicle Cabin Atmosphere Monitor (VCAM), this software analyzes the relative abundance ratios for N2, O2, Ar, and CO2 as a function of time and constructs their best-estimate mean. A histogram is first built of all abundance ratios for each of the species vs time. The abundance peaks corresponding to the intended measurement and any obfuscating background are then separated via standard peak-finding techniques in histogram space. A voting scheme is then used to include/exclude this particular time sample in the final average based on its membership to the intended measurement or the background population. This results in a robust and reasonable estimate of the abundance of trace components such as CO2 and Ar even in the presence of obfuscating backgrounds internal to the VCAM device. VCAM can provide a means for monitoring the air within the enclosed environments, such as the ISS (International Space Station), Crew Exploration Vehicle (CEV), a Lunar Habitat, or another vehicle traveling to Mars. Its miniature pre-concentrator, gas chromatograph (GC), and mass spectrometer can provide unbiased detection of a large number of organic species as well as MCA analysis. VCAM s software can identify the concentration of trace chemicals and whether the chemicals are on a targeted list of hazardous compounds. This innovation s performance and reliability on orbit, along with the ground team s assessment of its raw data and analysis results, will validate its technology for future use and development.
NASA Astrophysics Data System (ADS)
King, Jeremy R.
1997-06-01
Elemental abundances are presented for the metal-poor ([Fe/H] =-1.50) common proper motion pair HD 134439 and HD 134440. The abundances for the two stars are in very good agreement, with the neutral species showing only a small difference (˜0.05 dex) which is well within the statistical and Teff uncertainties. The essentially identical abundances, kinematics, and parallaxes of the two stars indicate that they share a common history. This history, however, appears to be different than other metal-poor stars. Suggestions, based on kinematic evidence, that these two-stars are representative of a distinct accretion event are corroborated by our abundance ratios, which indicate [Mg/Fe], [Si/Fe], and [Ca/Fe] are consistently some ˜0.3 dex lower than the vast majority of metal-poor field stars. Such underabundances have been predicted in environments like dwarf Spheroidals and the Magellanic Clouds. Moreover, our abundance ratio deficiencies are consistent with those recently observed in the the anomalously young globular clusters Rup 106 and Pal 12, which have been alleged to have been accreted from the Magellanic Clouds. The [Fe/H] and retrograde motion of the common proper motion pair are characteristic of the subset of Galactic globular clusters suggested by Rodgers & Paltoglou [ApJ, 283, L5 (1984)] to have been coalesced from satellite galaxies. We also call attention to the metal-poor subgiant BD+03 740 as another possible representative of an accreted or chaotically formed member of the halo field. If recent Fe analyses of this star are correct, then [Mg/Fe] and [0/Fe] are 0.5 dex lower than in other metal-poor field stars. This star also has a relatively low photometrically inferred age; relative youth has been noted as a possible characteristic of accreted field populations, and is qualitatively consistent with the young ages of the purportedly accreted globular clusters Rup 106, Pal 12, Ter 7, and Arp 2. Additionally, the revised [O/Fe] ratio for BD+03 740
Abundance Ratios in a Large Sample of Emps with VLT+UVES
NASA Astrophysics Data System (ADS)
Hill, Vanessa; Cayrel, Roger; Spite, Monique; Bonifacio, Piercarlo; Eric, Depagne; Patrick, François; Timothy, Beers C.; Johannes, Andersen; Beatriz, Barbuy; Birgitta, Nordström
Constraints on Early Galactic Enrichement from a large sample of Extremely Metal Poor Stars I will present the overall results from an large effort conducted at ESO-VLT+UVES to measure abundances in a sample of extremely metal-poor stars (EMPS) from high-resolution and high signal to noise spectra. More than 70 EMPS with [Fe/H]<-2.7 were observed equally distributed between turnoff and giants stars and very precise abundance ratios could be derived thanks to the high quality of the data. Among the results those of specific interest are lithium measurements in unevolved EMPS the much debated abundance of oxygen in the early galaxy (we present [OI] line measurements down to [O/Fe]=-3.5) and the trends of alpha elements iron group elements and Zinc. The scatter around these trends will also be discussed taking advantage of the small observationnal error-bars of this dataset. The implications on the early Galactic enrichement will be rewiewed while more specific topics covered by this large effort (and large team) will be adressed in devoted posters.
NASA Astrophysics Data System (ADS)
Lee, Duane M.; Johnston, Kathryn V.; Sen, Bodhisattva; Jessop, Will
2016-08-01
In this study we tested the prospects of using 2D chemical abundance ratio distributions (CARDs) found in stars of the stellar halo to determine its formation history. First, we used simulated data from eleven ``MW-like'' halos to generate satellite template sets of 2D CARDs of accreted dwarf satellites which are comprised of accreted dwarfs from various mass regimes and epochs of accretion. Next, we randomly drew samples of ~ 103-4 mock observations of stellar chemical abundance ratios ([α/Fe], [Fe/H]) from those eleven halos to generate samples of the underlying densities for our CARDs to be compared to our templates in our analysis. Finally, we used the expectation-maximization algorithm to derive accretion histories in relation to the satellite template set (STS) used and the sample size. For certain STS used we typically can identify the relative mass contributions of all accreted satellites to within a factor of 2. We also find that this method is particularly sensitive to older accretion events involving low-luminous dwarfs e.g. ultra-faint dwarfs - precisely those events that are too ancient to be seen by phase-space studies of stars and too faint to be seen by high-z studies of the early Universe. Since our results only exploit two chemical dimensions and near-future surveys promise to provide ~ 6-9 dimensions, we conclude that these new high-resolution spectroscopic surveys of the stellar halo will allow us (given the development of new CARD-generating dwarf models) to recover the luminosity function of infalling dwarf galaxies - and the detailed accretion history of the halo - across cosmic time.
NASA Astrophysics Data System (ADS)
Lee, Duane Morris; Johnston, Kathryn V.; Sen, Bodhisattva; Jessop, Will
2015-08-01
In this study we tested the prospects of using 2D chemical abundance ratio distributions (CARDs) found in stars of the stellar halo to determine its formation history. First, we used simulated data from eleven ``MW-like'' halos to generate satellite template sets of 2D CARDs of accreted dwarf satellites which are comprised of accreted dwarfs from various mass regimes and epochs of accretion. Next, we randomly drew samples of ~103-4 mock observations of stellar chemical abundance ratios ([α/Fe], [Fe/H]) from those eleven halos to generate samples of the underlying densities for our CARDs to be compared to our templates in our analysis. Finally, we used the expectation-maximization algorithm to derive accretion histories in relation to the satellite template set (STS) used and the sample size. For certain STS used we typically can identify the relative mass contributions of all accreted satellites to within a factor of 2. We also find that this method is particularly sensitive to older accretion events involving low-luminous dwarfs e.g. ultra-faint dwarfs --- precisely those events that are too ancient to be seen by phase-space studies of stars and too faint to be seen by high-z studies of the early Universe. Since our results only exploit two chemical dimensions and near-future surveys promise to provide ~6-9 dimensions, we conclude that these new high-resolution spectroscopic surveys of the stellar halo will allow us (given the development of new CARD-generating dwarf models) to recover the luminosity function of infalling dwarf galaxies --- and the detailed accretion history of the halo --- across cosmic time.
NASA Astrophysics Data System (ADS)
Lee, Duane M.; Johnston, Kathryn V.; Sen, Bodhisattva; Jessop, Will
2015-03-01
Observational studies of halo stars during the past two decades have placed some limits on the quantity and nature of accreted dwarf galaxy contributions to the Milky Way (MW) stellar halo by typically utilizing stellar phase-space information to identify the most recent halo accretion events. In this study we tested the prospects of using 2D chemical abundance ratio distributions (CARDs) found in stars of the stellar halo to determine its formation history. First, we used simulated data from 11 “MW-like” halos to generate satellite template sets (STSs) of 2D CARDs of accreted dwarf satellites, which are composed of accreted dwarfs from various mass regimes and epochs of accretion. Next, we randomly drew samples of ˜103-4 mock observations of stellar chemical abundance ratios ([α/Fe], [Fe/H]) from those 11 halos to generate samples of the underlying densities for our CARDs to be compared to our templates in our analysis. Finally, we used the expectation-maximization algorithm to derive accretion histories in relation to the STS used and the sample size. For certain STSs used we typically can identify the relative mass contributions of all accreted satellites to within a factor of two. We also find that this method is particularly sensitive to older accretion events involving low-luminosity dwarfs, e.g., ultra-faint dwarfs—precisely those events that are too ancient to be seen by phase-space studies of stars and too faint to be seen by high-z studies of the early universe. Since our results only exploit two chemical dimensions and near-future surveys promise to provide ˜6-9 dimensions, we conclude that these new high-resolution spectroscopic surveys of the stellar halo will allow us to recover its accretion history—and the luminosity function of infalling dwarf galaxies—across cosmic time.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Lee, Duane M.; Johnston, Kathryn V.; Sen, Bodhisattva
Observational studies of halo stars during the past two decades have placed some limits on the quantity and nature of accreted dwarf galaxy contributions to the Milky Way (MW) stellar halo by typically utilizing stellar phase-space information to identify the most recent halo accretion events. In this study we tested the prospects of using 2D chemical abundance ratio distributions (CARDs) found in stars of the stellar halo to determine its formation history. First, we used simulated data from 11 “MW-like” halos to generate satellite template sets (STSs) of 2D CARDs of accreted dwarf satellites, which are composed of accreted dwarfsmore » from various mass regimes and epochs of accretion. Next, we randomly drew samples of ∼10{sup 3–4} mock observations of stellar chemical abundance ratios ([α/Fe], [Fe/H]) from those 11 halos to generate samples of the underlying densities for our CARDs to be compared to our templates in our analysis. Finally, we used the expectation-maximization algorithm to derive accretion histories in relation to the STS used and the sample size. For certain STSs used we typically can identify the relative mass contributions of all accreted satellites to within a factor of two. We also find that this method is particularly sensitive to older accretion events involving low-luminosity dwarfs, e.g., ultra-faint dwarfs—precisely those events that are too ancient to be seen by phase-space studies of stars and too faint to be seen by high-z studies of the early universe. Since our results only exploit two chemical dimensions and near-future surveys promise to provide ∼6–9 dimensions, we conclude that these new high-resolution spectroscopic surveys of the stellar halo will allow us to recover its accretion history—and the luminosity function of infalling dwarf galaxies—across cosmic time.« less
Actinide abundances in ordinary chondrites
NASA Technical Reports Server (NTRS)
Hagee, B.; Bernatowicz, T. J.; Podosek, F. A.; Johnson, M. L.; Burnett, D. S.
1990-01-01
Measurements of actinide and light REE (LREE) abundances and of phosphate abundances in equilibrated ordinary chondrites were obtained and were used to define the Pu abundance in the solar system and to determine the degree of variation of actinide and LREE abundances. The results were also used to compare directly the Pu/U ratio with the earlier obtained ratio determined indirectly, as (Pu/Nd)x(Nd/U), assuming that Pu behaves chemically as a LREE. The data, combined with high-accuracy isotope-dilution data from the literature, show that the degree of gram-scale variability of the Th, U, and LREE abundances for equilibrated ordinary chondrites is a factor of 2-3 for absolute abundances and up to 50 percent for relative abundances. The observed variations are interpreted as reflecting the differences in the compositions and/or proportions of solar nebula components accreted to ordinary chondrite parent bodies.
CO/H2 Abundance Ratio ≈ 10-4 in a Protoplanetary Disk
NASA Astrophysics Data System (ADS)
France, Kevin; Herczeg, Gregory J.; McJunkin, Matthew; Penton, Steven V.
2014-10-01
The relative abundances of atomic and molecular species in planet-forming disks around young stars provide important constraints on photochemical disk models and provide a baseline for calculating disk masses from measurements of trace species. A knowledge of absolute abundances, those relative to molecular hydrogen (H2), are challenging because of the weak rovibrational transition ladder of H2 and the inability to spatially resolve different emission components within the circumstellar environment. To address both of these issues, we present new contemporaneous measurements of CO and H2 absorption through the "warm molecular layer" of the protoplanetary disk around the Classical T Tauri Star RW Aurigae A. We use a newly commissioned observing mode of the Hubble Space Telescope Cosmic Origins Spectrograph to detect warm H2 absorption in this region for the first time. An analysis of the emission and absorption spectrum of RW Aur shows components from the accretion region near the stellar photosphere, the molecular disk, and several outflow components. The warm H2 and CO absorption lines are consistent with a disk origin. We model the 1092-1117 Å spectrum of RW Aur to derive log10 N(H2) = 19.90+0.33-0.22 cm-2 at T rot(H2) = 440 ± 39 K. The CO A - X bands observed from 1410 to 1520 Å are best fit by log10 N(CO) = 16.1 +0.3-0.5 cm-2 at T rot(CO) = 200+650-125 K. Combining direct measurements of the H I, H2, and CO column densities, we find a molecular fraction in the warm disk surface of f H2 >= 0.47 and derive a molecular abundance ratio of CO/H2 = 1.6+4.7-1.3 × 10-4, both consistent with canonical interstellar dense cloud values. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555.
Kirkpatrick, C.; Conway, C.J.; Jones, P.B.
2006-01-01
The frequency of wild and prescribed fires in montane forests of the southwestern United States has increased after a century of fire suppression and subsequent fuels accumulation. To assess the effects of recent fires (median time since fire = 6 yr) on the montane forest bird community, we surveyed birds in 8 Sky Island mountain ranges in southeastern Arizona, USA, and examined how the distribution (i.e., presence-absence) of 65 species and relative abundance of 16 species correlated with evidence of severe and less severe fire at >1,500 survey points. We detected associations between fire and bird presence-absence for 17% of the 65 species analyzed and between fire and bird relative abundance for 25% of the 16 species analyzed. Most species (73%) were positively associated with burned areas and displayed stronger associations (i.e., more extreme odds ratios) with survey points that had evidence of severe as opposed to less severe fire. Positive associations with severe fire were strong (>3 to 1 odds) for western wood-pewee (Contopus sordidulus) and house wren (Troglodytes aedon), and negative associations with severe fire were strong for warbling vireo (Vireo gilvus) and red-breasted nuthatch (Sitta canadensis). Although recent fires appear to have had a positive effect on the distribution and relative abundance of several montane forest bird species in the region, these species are not the open-woodland birds that we would have expected to have benefited from fire based on previous research. Nevertheless, our results confirm associations between fire and bird presence-absence and relative abundance reported previously for 7 species of birds. Our results also provide new information for Grace's warbler (Dendroica graciae) and greater pewee (C. pertinax), 2 species for which fire data were formerly lacking. Managers can use these data to make and test predictions about the effects of future fires, both severe and less severe, on montane forest birds in the
Penguin tissue as a proxy for relative krill abundance in East Antarctica during the Holocene.
Huang, Tao; Sun, Liguang; Long, Nanye; Wang, Yuhong; Huang, Wen
2013-09-30
Antarctic krill (Euphausia superba) is a key component of the Southern Ocean food web. It supports a large number of upper trophic-level predators, and is also a major fishery resource. Understanding changes in krill abundance has long been a priority for research and conservation in the Southern Ocean. In this study, we performed stable isotope analyses on ancient Adélie penguin tissues and inferred relative krill abundance during the Holocene epoch from paleodiets of Adélie penguin (Pygoscelis adeliae), using inverse of δ¹⁵N (ratio of ¹⁵N/¹⁴N) value as a proxy. We find that variations in krill abundance during the Holocene are in accord with episodes of regional climate changes, showing greater krill abundance in cold periods. Moreover, the low δ¹⁵N values found in modern Adélie penguins indicate relatively high krill availability, which supports the hypothesis of krill surplus in modern ages due to recent hunt for krill-eating seals and whales by humans.
NASA Astrophysics Data System (ADS)
Nichols, J. E.; Jackson, S. T.; Booth, R. K.; Pendall, E. G.; Huang, Y.
2005-12-01
Sediment cores from ombrotrophic peat bogs provide sensitive records of changes in precipitation/evaporation (P/E) balance. Various proxies have been developed to reconstruct surface moisture conditions in peat bogs, including testate amoebae, plant macrofossils, and peat humification. Studying species composition of testate amoeba assemblages is time consuming and requires specialized training. Humification index can be influenced by environmental factors other than moisture balance. The plant macrofossil proxy is less quantitative and cannot be performed on highly decomposed samples. We demonstrate that the ratio of C23 alkane to C29 alkane abundance may provide a simple alternative or complementary means of tracking peatland water-table depth. Data for this proxy can be collected quickly using a small sample (100 mg dry). Water-table depth decreases during drought, and abundance of Sphagnum, the dominant peat-forming genus, decreases as vascular plants increase. Sphagnum moss produces mainly medium chain-length alkanes (C21-C25) while vascular plants (grasses and shrubs) produce primarily longer chain-length alkanes (C27-C31). Therefore, C23:C29 n-alkane ratios quantitatively track the water table depth fluctuations in peat bogs. We compared C23:C29 n-alkane ratios in a core from Minden Bog (southeastern Michigan) with water table depth reconstructions based on testate-amoeba assemblages and humification. The 184-cm core spans the past ~3kyr of continuous peat deposition in the bog. Our results indicate that the alkane ratios closely track the water table depth variations, with C29 most abundant during droughts. We also explored the use of D/H ratios in Sphagnum biomarkers as a water-table depth proxy. Compound-specific hydrogen isotope ratio analyses were performed on Sphagnum biomarkers: C23 and C25 alkane and C24 acid. Dry periods are represented in these records by an enrichment of deuterium in these Sphagnum-specific compounds. These events also correlate
Actinide abundances in ordinary chondrites
Hagee, B.; Bernatowicz, T.J.; Podosek, F.A.; Johnson, M.L.; Burnett, D.S.; Tatsumoto, M.
1990-01-01
Measurements of 244Pu fission Xe, U, Th, and light REE (LREE) abundances, along with modal petrographic determinations of phosphate abundances, were carried out on equilibrated ordinary chondrites in order to define better the solar system Pu abundance and to determine the degree of variation of actinide and LREE abundances. Our data permit comparison of the directly measured Pu/ U ratio with that determined indirectly as (Pu/Nd) ?? (Nd/U) assuming that Pu behaves chemically as a LREE. Except for Guaren??a, and perhaps H chondrites in general, Pu concentrations are similar to that determined previously for St. Se??verin, although less precise because of higher trapped Xe contents. Trapped 130Xe 136Xe ratios appear to vary from meteorite to meteorite, but, relative to AVCC, all are similar in the sense of having less of the interstellar heavy Xe found in carbonaceous chondrite acid residues. The Pu/U and Pu/Nd ratios are consistent with previous data for St. Se??verin, but both tend to be slightly higher than those inferred from previous data on Angra dos Reis. Although significant variations exist, the distribution of our Th/U ratios, along with other precise isotope dilution data for ordinary chondrites, is rather symmetric about the CI chondrite value; however, actinide/(LREE) ratios are systematically lower than the CI value. Variations in actinide or LREE absolute and relative abundances are interpreted as reflecting differences in the proportions and/or compositions of more primitive components (chondrules and CAI materials?) incorporated into different regions of the ordinary chondrite parent bodies. The observed variations of Th/U, Nd/U, or Ce/U suggest that measurements of Pu/U on any single equilibrated ordinary chondrite specimen, such as St. Se??verin, should statistically be within ??20-30% of the average solar system value, although it is also clear that anomalous samples exist. ?? 1990.
Crimmins, Shawn M.; Walleser, Liza R.; Hertel, Dan R.; McKann, Patrick C.; Rohweder, Jason J.; Thogmartin, Wayne E.
2016-01-01
There is growing need to develop models of spatial patterns in animal abundance, yet comparatively few examples of such models exist. This is especially true in situations where the abundance of one species may inhibit that of another, such as the intensively-farmed landscape of the Prairie Pothole Region (PPR) of the central United States, where waterfowl production is largely constrained by mesocarnivore nest predation. We used a hierarchical Bayesian approach to relate the distribution of various land-cover types to the relative abundances of four mesocarnivores in the PPR: coyote Canis latrans, raccoon Procyon lotor, red fox Vulpes vulpes, and striped skunk Mephitis mephitis. We developed models for each species at multiple spatial resolutions (41.4 km2, 10.4 km2, and 2.6 km2) to address different ecological and management-related questions. Model results for each species were similar irrespective of resolution. We found that the amount of row-crop agriculture was nearly ubiquitous in our best models, exhibiting a positive relationship with relative abundance for each species. The amount of native grassland land-cover was positively associated with coyote and raccoon relative abundance, but generally absent from models for red fox and skunk. Red fox and skunk were positively associated with each other, suggesting potential niche overlap. We found no evidence that coyote abundance limited that of other mesocarnivore species, as might be expected under a hypothesis of mesopredator release. The relationships between relative abundance and land-cover types were similar across spatial resolutions. Our results indicated that mesocarnivores in the PPR are most likely to occur in portions of the landscape with large amounts of agricultural land-cover. Further, our results indicated that track-survey data can be used in a hierarchical framework to gain inferences regarding spatial patterns in animal relative abundance.
Everyone knows what abundant and rare species are, but quantifying the concept proves elusive. As part of an EPA/USGS project to assess near-coastal species vulnerability to climate change affects, we designed a hybrid approach to determine species relative abundance at an ecoreg...
Carbon and nitrogen abundances determined from transition layer lines
NASA Technical Reports Server (NTRS)
Boehm-Vitense, Erika; Mena-Werth, Jose
1992-01-01
The possibility of determining relative carbon, nitrogen, and silicon abundances from the emission-line fluxes in the lower transition layers between stellar chromospheres and coronae is explored. Observations for main-sequence and luminosity class IV stars with presumably solar element abundances show that for the lower transition layers Em = BT sup -gamma. For a given carbon abundance the constants gamma and B in this relation can be determined from the C II and C IV emission-line fluxes. From the N V and S IV lines, the abundances of these elements relative to carbon can be determined from their surface emission-line fluxes. Ratios of N/C abundances determined in this way for some giants and supergiants agree within the limits of errors with those determined from molecular bands. For giants, an increase in the ratio of N/C at B-V of about 0.8 is found, as expected theoretically.
Stellar oxygen abundances. I - A resolution to the 7774 A O I abundance discrepancy
NASA Astrophysics Data System (ADS)
King, Jeremy R.
1993-09-01
We investigate the discrepancy between O/Fe abundance ratios of metal-poor stars derived from the 7774 A O I triplet and O/Fe ratios determined from other oxygen lines. We propose a possible resolution to this discrepancy which also eliminates the correlation of O/Fe and T(eff) found in a recent 7774 A O I analysis. The equivalent widths of Abia & Rebolo (1989) are found to be systematically too high by 25 percent. Arguments are presented that current temperature estimates for halo stars are 150-200 K too low. Using the guidance of both model atmospheres and other empirical color-T(eff) relations, we construct new color temperature relations for metal-poor stars. These relations are tied to the temperature scale of Saxner & Hammarback (1985) for metal-rich stars. We use (b-y) and (V-K) indices to redetermine values of T(eff) for a handful of halo stars. (B-V)-T(eff) relations which do not take into account the effects of metallicity are found to be inadequate. Revised O/Fe ratios are determined using the new temperature scale. The mean abundance ratio of the reanalyzed halo dwarfs is about +0.52. There is no trend of O/Fe with Fe/H or T(eff).
DOE Office of Scientific and Technical Information (OSTI.GOV)
Emprechtinger, M.; Lis, D. C.; Monje, R. R.
2013-03-01
We present Herschel/HIFI observations of 30 transitions of water isotopologues toward the high-mass star-forming region NGC 6334 I. The line profiles of H{sup 16} {sub 2}O, H{sup 17} {sub 2}O, H{sup 18} {sub 2}O, and HDO show a complex pattern of emission and absorption components associated with the embedded hot cores, a lower-density envelope, two outflow components, and several foreground clouds, some associated with the NGC 6334 complex, others seen in projection against the strong continuum background of the source. Our analysis reveals an H{sub 2}O ortho/para ratio of 3 {+-} 0.5 in the foreground clouds, as well as themore » outflow. The water abundance varies from {approx}10{sup -8} in the foreground clouds and the outer envelope to {approx}10{sup -6} in the hot core. The hot core abundance is two orders of magnitude below the chemical model predictions for dense, warm gas, but within the range of values found in other Herschel/HIFI studies of hot cores and hot corinos. This may be related to the relatively low gas and dust temperature ({approx}100 K), or time-dependent effects, resulting in a significant fraction of water molecules still locked up in dust grain mantles. The HDO/H{sub 2}O ratio in NGC 6334 I, {approx}2 Multiplication-Sign 10{sup -4}, is also relatively low, but within the range found in other high-mass star-forming regions.« less
The Faber–Jackson relation and Fundamental Plane from halo abundance matching
Desmond, Harry; Wechsler, Risa H.
2016-11-02
The Fundamental Plane (FP) describes the relation between the stellar mass, size, and velocity dispersion of elliptical galaxies; the Faber–Jackson relation (FJR) is its projection on to {mass, velocity} space. In this work, we re-deploy and expand the framework of Desmond & Wechsler to ask whether abundance matching-based Λ-cold dark matter models which have shown success in matching the spatial distribution of galaxies are also capable of explaining key properties of the FJR and FP, including their scatter. Within our framework, agreement with the normalization of the FJR requires haloes to expand in response to disc formation. We find thatmore » the tilt of the FP may be explained by a combination of the observed non-homology in galaxy structure and the variation in mass-to-light ratio produced by abundance matching with a universal initial mass function, provided that the anisotropy of stellar motions is taken into account. However, the predicted scatter around the FP is considerably increased by situating galaxies in cosmologically motivated haloes due to the variations in halo properties at fixed stellar mass and appears to exceed that of the data. Finally, this implies that additional correlations between galaxy and halo variables may be required to fully reconcile these models with elliptical galaxy scaling relations.« less
Mulieri, P R; Olea, M S; Patitucci, L D; Battán-Horenstein, M
2018-06-07
Abundance of sarcosaprophagous Calyptratae species was monitored by using baited traps and active captures with hand net. Analysis of field data collected in three protected areas in the Valdivian temperate forest of South America (Lanín National Park, Lago Puelo National Park, and Los Alerces National Park) indicated that bottle traps baited with putrescine is a reliable method to estimate local abundance of sarcosaprophagous species by comparison to the active capture method. Also, we describe and compare general patterns of sex bias for four dominant species: Sarconesia magellanica (Le Guillou), Calliphora vicina Robineau-Desvoidy, Microcerella spinigena (Rondani), and Oxysarcodexia varia (Walker). From these analyses, it can be concluded that abundance fluctuations of flies showed significant relationship between the sampling methods. This study showed that besides the expected interspecific differences in trapping efficiency, there are acute intraspecific differences of sex ratios between sampling methods.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Wunschel, David S.; Kreuzer-Martin, Helen W.; Antolick, Kathryn C.
2009-12-01
This report describes method development and preliminary evaluation for analyzing castor samples for signatures of purifying ricin. Ricin purification from the source castor seeds is essentially a problem of protein purification using common biochemical methods. Indications of protein purification will likely manifest themselves as removal of the non-protein fractions of the seed. Two major, non-protein, types of biochemical constituents in the seed are the castor oil and various carbohydrates. The oil comprises roughly half the seed weight while the carbohydrate component comprises roughly half of the remaining “mash” left after oil and hull removal. Different castor oil and carbohydrate componentsmore » can serve as indicators of specific toxin processing steps. Ricinoleic acid is a relatively unique fatty acid in nature and is the most abundant component of castor oil. The loss of ricinoleic acid indicates a step to remove oil from the seeds. The relative amounts of carbohydrates and carbohydrate-like compounds, including arabinose, xylose, myo-inositol fucose, rhamnose, glucosamine and mannose detected in the sample can also indicate specific processing steps. For instance, the differential loss of arabinose relative to mannose and N-acetyl glucosamine indicates enrichment for the protein fraction of the seed using protein precipitation. The methods developed in this project center on fatty acid and carbohydrate extraction from castor samples followed by derivatization to permit analysis by gas chromatography-mass spectrometry (GC-MS). Method descriptions herein include: the source and preparation of castor materials used for method evaluation, the equipment and description of procedure required for chemical derivatization, and the instrument parameters used in the analysis. Two types of derivatization methods describe analysis of carbohydrates and one procedure for analysis of fatty acids. Two types of GC-MS analysis is included in the method development
DOE Office of Scientific and Technical Information (OSTI.GOV)
Conroy, Charlie; Graves, Genevieve J.; Van Dokkum, Pieter G.
2014-01-01
The stellar populations of galaxies hold vital clues to their formation histories. In this paper we present results based on modeling stacked spectra of early-type galaxies drawn from the Sloan Digital Sky Survey as a function of velocity dispersion, σ, from 90 km s{sup –1} to 300 km s{sup –1}. The spectra are of extremely high quality, with typical signal-to-noise ratio of 1000 Å{sup –1}, and a wavelength coverage of 4000 Å –8800 Å. Our population synthesis model includes variation in 16 elements from C to Ba, a two-component star formation history, the shift in effective temperature, Δ T {submore » eff}, of the stars with respect to a solar metallicity isochrone, and the stellar initial mass function, among other parameters. In our approach we fit the full optical spectra rather than a select number of spectral indices and are able to, for the first time, measure the abundances of the elements V, Cr, Mn, Co, and Ni from the integrated light of distant galaxies. Our main results are as follows: (1) light-weighted stellar ages range from 6-12 Gyr from low to high σ; (2) [Fe/H] varies by less than 0.1 dex across the entire sample; (3) Mg closely tracks O, and both increase from ≈0.0 at low σ to ∼0.25 at high σ; Si and Ti show a shallower rise with σ, and Ca tracks Fe rather than O; (4) the iron peak elements V, Cr, Mn, and Ni track Fe, while Co tracks O, suggesting that Co forms primarily in massive stars; (5) C and N track O over the full sample and [C/Fe] and [N/Fe] exceed 0.2 at high σ; and (6) the variation in Δ T {sub eff} with total metallicity closely follows theoretical predictions based on stellar evolution theory. This last result is significant because it implies that we are robustly solving not only for the detailed abundance patterns but also the detailed temperature distributions (i.e., isochrones) of the stars in these galaxies. A variety of tests reveal that the systematic uncertainties in our measurements are probably 0
Everyone knows what abundant and rare species are, but quantifying the concept proves elusive. As part of an EPA/USGS project to assess near-coastal species vulnerability to climate change affects, we designed a hybrid approach to determine species relative abundance at an ecoreg...
Effect of Game Management on Wild Red-Legged Partridge Abundance
Díaz-Fernández, Silvia; Arroyo, Beatriz; Casas, Fabián; Martinez-Haro, Monica; Viñuela, Javier
2013-01-01
The reduction of game and fish populations has increased investment in management practices. Hunting and fishing managers use several tools to maximize harvest. Managers need to know the impact their management has on wild populations. This issue is especially important to improve management efficacy and biodiversity conservation. We used questionnaires and field bird surveys in 48 hunting estates to assess whether red-legged partridge Alectoris rufa young/adult ratio and summer abundance were related to the intensity of management (provision of supplementary food and water, predator control and releases of farm-bred partridges), harvest intensity or habitat in Central Spain. We hypothesized that partridge abundance would be higher where management practices were applied more intensively. Variation in young/adult ratio among estates was best explained by habitat, year and some management practices. Density of feeders and water points had a positive relationship with this ratio, while the density of partridges released and magpies controlled were negatively related to it. The variables with greatest relative importance were feeders, releases and year. Variations in post-breeding red-legged partridge abundance among estates were best explained by habitat, year, the same management variables that influenced young/adult ratio, and harvest intensity. Harvest intensity was negatively related to partridge abundance. The other management variables had the same type of relationship with abundance as with young/adult ratio, except magpie control. Variables with greatest relative importance were habitat, feeders, water points, releases and harvest intensity. Our study suggests that management had an overall important effect on post-breeding partridge abundance. However, this effect varied among tools, as some had the desired effect (increase in partridge abundance), whereas others did not or even had a negative relationship (such as release of farm-reared birds) and can be
Element abundances at high redshift
NASA Technical Reports Server (NTRS)
Meyer, David M.; Welty, D. E.; York, D. G.
1989-01-01
Abundances of Si(+), S(+), Cr(+), Mn(+), Fe(_), and Zn(+) are considered for two absorption-line systems in the spectrum of the QSO PKS 0528 - 250. Zinc and sulfur are underabundant, relative to H, by a factor of 10 compared to their solar and Galactic interstellar abundances. The silicon-, chromium-, iron-, and nickel-to-hydrogen ratios are less than the solar values and comparable to the local interstellar ratios. A straightforward interpretation is that nucleosynthesis in these high-redshift systems has led to only about one-tenth as much heavy production as in the gas clouds around the sun, and that the amount of the observed underabundances attributable to grain depletion is small. The dust-to-gas ratio in these clouds is less than 8 percent of the Galactic value.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Isselhardt, Brett H.
2011-09-01
Resonance Ionization Mass Spectrometry (RIMS) has been developed as a method to measure relative uranium isotope abundances. In this approach, RIMS is used as an element-selective ionization process to provide a distinction between uranium atoms and potential isobars without the aid of chemical purification and separation. We explore the laser parameters critical to the ionization process and their effects on the measured isotope ratio. Specifically, the use of broad bandwidth lasers with automated feedback control of wavelength was applied to the measurement of 235U/ 238U ratios to decrease laser-induced isotopic fractionation. By broadening the bandwidth of the first laser inmore » a 3-color, 3-photon ionization process from a bandwidth of 1.8 GHz to about 10 GHz, the variation in sequential relative isotope abundance measurements decreased from >10% to less than 0.5%. This procedure was demonstrated for the direct interrogation of uranium oxide targets with essentially no sample preparation. A rate equation model for predicting the relative ionization probability has been developed to study the effect of variation in laser parameters on the measured isotope ratio. This work demonstrates that RIMS can be used for the robust measurement of uranium isotope ratios.« less
DOE Office of Scientific and Technical Information (OSTI.GOV)
Shinnaka, Yoshiharu; Kawakita, Hideyo; Kobayashi, Hitomi
2012-04-20
The ortho-to-para abundance ratio (OPR) of cometary molecules is considered to be one of the primordial characteristics of cometary ices, and contains information concerning their formation. Water is the most abundant species in cometary ices, and OPRs of water in comets have been determined from infrared spectroscopic observations of H{sub 2}O rovibrational transitions so far. In this paper, we present a new method to derive OPR of water in comets from the high-dispersion spectrum of the rovibronic emission of H{sub 2}O{sup +} in the optical wavelength region. The rovibronic emission lines of H{sub 2}O{sup +} are sometimes contaminated by othermore » molecular emission lines but they are not affected seriously by telluric absorption compared with near-infrared observations. Since H{sub 2}O{sup +} ions are mainly produced from H{sub 2}O by photoionization in the coma, the OPR of H{sub 2}O{sup +} is considered to be equal to that of water based on the nuclear spin conservation through the reaction. We have developed a fluorescence excitation model of H{sub 2}O{sup +} and applied it to the spectrum of comet C/2001 Q4 (NEAT). The derived OPR of water is 2.54{sup +0.32}{sub -0.25}, which corresponds to a nuclear spin temperature (T{sub spin}) of 30{sup +10}{sub -4} K. This is consistent with the previous value determined in the near-infrared for the same comet (OPR = 2.6 {+-} 0.3, T{sub spin} = 31{sup +11}{sub -5} K).« less
Temperature relations and abundance determinations in H II regions
NASA Astrophysics Data System (ADS)
Arellano-Córdova, K. Z.; Rodríguez, M.; Delgado-Inglada, G.
2017-11-01
Most abundance determinations in H II regions, especially for extragalactic regions, are based on the use of temperature relations, usually between Te[N II] and Te[O III]. The calibration of strong-line methods also generally rely on the use of these relations. We explore here the reliability of old and new Te[N II]-Te[O III] relations, their dispersions, and their effects on the calculation of chemical abundances. In order to do so, we have compiled and analyzed in a homogeneous way a sample of 155 H II regions that have measurements of both temperatures. We find that some of the largest departures from the temperature relation are probably due to shocks affecting Te[N II]. We consider the effects of recombination in Te[N II] and of line blending in Te[O III], and find a residual dependence of the temperature relation on the degree of ionization. We provide new robust fits of the relation and show that our fits lead to better abundance determinations. Our fits are very similar to the most used temperature relation, based on a grid of photoionization models by Stasińska (1982), and variously cited as Campbell et al. (1986) or Garnett (1992).
Variations in iron and calcium abundances during solar flares
NASA Astrophysics Data System (ADS)
Antonucci, E.; Martin, R.
1995-07-01
Evidence for variations in iron and calcium abundances during the impulsive phase of solar flares has been obtained by analyzing the Ca XIX and Fe XXV spectra, detected with the Bent Crystal Spectrometer of the Solar Maximum Mission. The plasma thermal conditions have been investigated by considering different temperature indicators: namely, the temperatures TCa and TFe, derived from the intensity ratios of the dielectronic recombination satellites to the resonance line, and the temperature TCaFe, calculated from the ratio of the resonance lines of Ca XIX and Fe XXV, which is also depending on the Fe/Ca abundance ratio. The observed values of TCa and TFe can be ascribed to the specific characteristics of the plasma therma distribution, the corresponding values of TCaFe can be explained by allowing also for variations in the Fe/Ca abundance ratio relative to the photospheric ratio by a factor within 0.2 and 2.4. According to the observed abundance variations, the events analyzed can be divided in Ca-rich and Fe-rich flares.
NASA Astrophysics Data System (ADS)
King, Jeremy
1994-04-01
This dissertation addresses several issues concerning stellar oxygen abundances. The 7774 {\\AA} O I triplet equivalent widths of Abia & Rebolo [1989, AJ, 347, 186] for metal-poor dwarfs are found to be systematically too high. I also argue that current effective temperatures used in halo star abundance studies may be ~150 K too low. New color-Teff relations are derived for metal-poor stars. Using the revised Teff values and improved equivalent widths for the 7774A O I triplet, the mean [O/Fe] ratio for a handful of halo stars is found to be +0.52 with no dependence on Teff or [Fe/H]. Possible cosmological implications of the hotter Teff scale are discussed along with additional evidence supporting the need for a higher temperature scale for metal-poor stars. Our Teff scale leads to a Spite Li plateau value of N(Li)=2.28 +/- 0.09. A conservative minimal primordial value of N(Li)=2.35 is inferred. If errors in the observations and models are considered, consistency with standard models of Big Bang nucleosynthesis is still achieved with this larger Li abundance. The revised Teff scale raises the observed B/Be ratio of HD 140283 from 10 to 12, making its value more comfortably consistent with the production of the observed B and Be by ordinary spallation. Our Teff values are found to be in good agreement with values predicted from both the Victoria and Yale isochrone color-Teff relations. Thus, it appears likely that no changes in globular cluster ages would result. Next, we examine the location of the break in the [O/Fe] versus [Fe/H] plane in a quantitative fashion. Analysis of a relatively homogeneous data set does not favor any unique break point in the range -1.7 = [Fe/H] = -1.0. The red giant O dataset (from the literature) used in this analysis also indicates that [O/Fe] is constant in the halo (at least for [Fe/H] >/= -3), in agreement with the new results for halo dwarfs. We find that the gap in the observed [O/H] distribution, noted by Wheeler et al
Atmospheric Trace Gas Abundances and Stable Isotope Ratios via IR-LIF
NASA Technical Reports Server (NTRS)
Blake, Geoffrey A.
2004-01-01
We propose to develop new technologies with support provided by PIDDP that will enable the in situ measurements of abundances and stable isotope ratios in important radiatively and biogenically active gases such as carbon dioxide, carbon monoxide, water, methane, nitrous oxide, and hydrogen sulfide to very high precision (0.1 per mil or better for the isotopic ratios, for example). Such measurements, impossible at present, could provide pivotal new constraints on the global (bio)geochemical budgets of these critical species, and could also be used to examine the dynamics of atmospheric transport on Mars, Titan, and other solar system bodies. We believe the combination of solid state light sources with imaging of the IR laser induced fluorescence (IR-LIF) via newly available detector arrays will make such in situ measurements possible for the first time. Even under ambient terrestrial conditions, the LIF yield from vibrational excitation of species such as water and carbon dioxide should produce emission measures well in excess of ten billion photons/sec from samples volumes of order 1 c.c. These count rates can, in principle, yield detection limits into the sub-ppt range that are required for the in situ isotopic study of atmospheric trace gases. While promising, such technologies are relatively immature, but developing rapidly, and there are a great many uncertainties regarding their applicability to in situ IR-LIF planetary studies. We therefore feel PIDDP support will be critical to developing these new tools, and propose a three-year program to combine microchip near-IR lasers with low background detection axes and state-of-the-art HgCdTe detectors developed for astronomical spectroscopy to investigate the sensitivity of IR-LIF under realistic planetary conditions, to optimize the optical pumping and filtering schemes for important species, and to apply the spectrometer to the non-destructive measurement of stable isotopes in a variety of test samples. These
Modeled distribution and abundance of a pelagic seabird reveal trends in relation to fisheries
Renner, Martin; Parrish, Julia K.; Piatt, John F.; Kuletz, Kathy J.; Edwards, Ann E.; Hunt, George L.
2013-01-01
The northern fulmar Fulmarus glacialis is one of the most visible and widespread seabirds in the eastern Bering Sea and Aleutian Islands. However, relatively little is known about its abundance, trends, or the factors that shape its distribution. We used a long-term pelagic dataset to model changes in fulmar at-sea distribution and abundance since the mid-1970s. We used an ensemble model, based on a weighted average of generalized additive model (GAM), multivariate adaptive regression splines (MARS), and random forest models to estimate the pelagic distribution and density of fulmars in the waters of the Aleutian Archipelago and Bering Sea. The most important predictor variables were colony effect, sea surface temperature, distribution of fisheries, location, and primary productivity. We calculated a time series from the ratio of observed to predicted values and found that fulmar at-sea abundance declined from the 1970s to the 2000s at a rate of 0.83% (± 0.39% SE) per annum. Interpolating fulmar densities on a spatial grid through time, we found that the center of fulmar distribution in the Bering Sea has shifted north, coinciding with a northward shift in fish catches and a warming ocean. Our study shows that fisheries are an important, but not the only factor, shaping fulmar distribution and abundance trends in the eastern Bering Sea and Aleutian Islands.
Ortho-to-para abundance ratios of NH2 in 26 comets: implications for the real meaning of OPRs
NASA Astrophysics Data System (ADS)
Shinnaka, Yoshiharu; Kawakita, Hideyo; Jehin, Emmanuël; Decock, Alice; Hutsemékers, Damien; Manfroid, Jean
2016-11-01
Abundance ratios of nuclear-spin isomers for cometary molecules having identical protons, such as water and ammonia, have been measured and discussed from the viewpoint that they are primordial characters in comet. In the case of ammonia, its ortho-to-para abundance ratio (OPR) is usually estimated from OPRs of NH2 because of difficulty in measuring OPR of ammonia directly. We report our survey for OPRs of NH2 in 26 comets. A weighted mean of ammonia OPRs for the comets is 1.12 ± 0.01 and no significant difference is found between the Oort Cloud comets and the Jupiter-family comets. These values correspond to ˜30 K as nuclear-spin temperatures. The OPRs of ammonia in comets probably reflect the physicochemical conditions in coma, rather than the conditions for the molecular formation or condensation in the pre-solar molecular cloud/the solar nebula, based on comparison of OPRs (and nuclear-spin temperatures) of ammonia with those of water, 14N/15N ratios in ammonia, and D/H ratios in water. The OPRs could be reset to a nuclear-spin weights ratio in solid phase and modified by interactions with protonated ions like H3O+, water clusters (H2O)n, ice grains, and paramagnetic impurities (such as O2 molecules and grains) in the inner coma gas. Relationship between the OPRs of ammonia and water is a clue to understanding the real meaning of the OPRs.
NASA Astrophysics Data System (ADS)
Nissen, P. E.
2016-09-01
Aims: A previous study of correlations between element abundances and ages of solar twin stars in the solar neighborhood is extended to include Sc, Mn, Cu, and Ba to obtain new information on the nucleosynthetic history of these elements. Methods: HARPS spectra with S/N ≳ 600 are used to derive very precise (σ ~ 0.01 dex) differential abundances of Sc, Mn, Cu, and Ba for 21 solar twins and the Sun. The analysis is based on MARCS model atmospheres with parameters determined from the excitation and ionization balance of Fe lines. Stellar ages with internal errors less than 1 Gyr are obtained by interpolation in the log g - Teff diagram between isochrones based on the Aarhus Stellar Evolution Code. Results: For stars younger than 6 Gyr, [Sc/Fe], [Mn/Fe], [Cu/Fe], and [Ba/Fe] are tightly correlated with stellar age, which is also the case for the other elements previously studied; linear relations between [X/Fe] and age have χ^2red ˜ 1, and for most stars the residuals do not depend on elemental condensation temperature. For ages between 6 and 9 Gyr, the [X/Fe] - age correlations break down and the stars split up into two groups having respectively high and low [X/Fe] for the odd-Z elements Na, Al, Sc, and Cu. Conclusions: While stars in the solar neighborhood younger than ~ 6 Gyr were formed from interstellar gas with a smooth chemical evolution, older stars seem to have originated from regions enriched by supernovae with different neutron excesses. Correlations between abundance ratios and stellar age suggest that: (I) Sc is made in Type II supernovae along with the α-capture elements; (II) the Type II to Ia yield ratio is about the same for Mn and Fe; (III) Cu is mainly made by the weak s-process in massive stars; (iv) the Ba/Y yield ratio for asymptotic giant branch stars increases with decreasing stellar mass; (v) [Y/Mg] and [Y/Al] can be used as chemical clocks when determining ages of solar metallicity stars. Based on data products from observations made
DOE Office of Scientific and Technical Information (OSTI.GOV)
Teske, Johanna K.; Cunha, Katia; Schuler, Simon C.
2013-12-01
The super-Earth exoplanet 55 Cnc e, the smallest member of a five-planet system, has recently been observed to transit its host star. The radius estimates from transit observations, coupled with spectroscopic determinations of mass, provide constraints on its interior composition. The composition of exoplanetary interiors and atmospheres are particularly sensitive to elemental C/O ratio, which to first order can be estimated from the host stars. Results from a recent spectroscopic study analyzing the 6300 Å [O I] line and two C I lines suggest that 55 Cnc has a carbon-rich composition (C/O = 1.12 ± 0.09). However, oxygen abundances derivedmore » using the 6300 Å [O I] line are highly sensitive to a Ni I blend, particularly in metal-rich stars such as 55 Cnc ([Fe/H] =0.34 ± 0.18). Here, we further investigate 55 Cnc's composition by deriving the carbon and oxygen abundances from these and additional C and O absorption features. We find that the measured C/O ratio depends on the oxygen lines used. The C/O ratio that we derive based on the 6300 Å [O I] line alone is consistent with the previous value. Yet, our investigation of additional abundance indicators results in a mean C/O ratio of 0.78 ± 0.08. The lower C/O ratio of 55 Cnc determined here may place this system at the sensitive boundary between protoplanetary disk compositions giving rise to planets with high (>0.8) versus low (<0.8) C/O ratios. This study illustrates the caution that must applied when determining planet host star C/O ratios, particularly in cool, metal-rich stars.« less
Report on carbon and nitrogen abundance studies
NASA Technical Reports Server (NTRS)
Boehm-Vitense, Erika
1991-01-01
The aim of the proposal was to determine the nitrogen to carbon abundance ratios from transition layer lines in stars with different T(sub eff) and luminosities. The equations which give the surface emission line fluxes and the measured ratio of the NV to CIV emission line fluxes are presented and explained. The abundance results are compared with those of photospheric abundance studies for stars in common with the photospheric investigations. The results show that the analyses are at least as accurate as the photospheric determinations. These studies can be extended to F and early G stars for which photospheric abundance determinations for giants are hard to do because molecular bands become too weak. The abundance determination in the context of stellar evolution is addressed. The N/C abundance ratio increases steeply at the point of evolution for which the convection zone reaches deepest. Looking at the evolution of the rotation velocities v sin i, a steep decrease in v sin i is related to the increasing depth of the convection zone. It is concluded that the decrease in v sin i for T(sub eff) less than or approximately = 5800 K is most probably due to the rearrangement of the angular momentum in the stars due to deep convective mixing. It appears that the convection zone is rotating with nearly depth independent angular momentum. Other research results and ongoing projects are discussed.
Space-based measurements of elemental abundances and their relation to solar abundances
NASA Technical Reports Server (NTRS)
Coplan, M. A.; Ogilvie, K. W.; Bochsler, P.; Geiss, J.
1990-01-01
The Ion Composition Instrument (ICI) aboard the ISEE-3/ICE spacecraft was in the solar wind continuously from August 1978 to December 1982. The results made it possible to establish long-term average solar wind abundance values for helium, oxygen, neon, silicon, and iron. The Charge-Energy-Mass instrument aboard the CCE spacecraft of the AMPTE mission has measured the abundance of these elements in the magnetosheath and has also added carbon, nitrogen, magnesium, and sulfur to the list. There is strong evidence that these magnetosheath abundances are representative of the solar wind. Other sources of solar wind abundances are Solar Energetic Particle experiments and Apollo lunar foils. When comparing the abundances from all of these sources with photospheric abundances, it is clear that helium is depleted in the solar wind while silicon and iron are enhanced. Solar wind abundances for carbon, nitrogen, oxygen, and neon correlate well with the photospheric values. The incorporation of minor ions into the solar wind appears to depend upon both the ionization times for the elements and the Coulomb drag exerted by the outflowing proton flux.
Inácio, Caio T; Magalhães, Alberto M T; Souza, Paulo O; Chalk, Phillip M; Urquiaga, Segundo
2018-05-01
Variations in the relative isotopic abundance of C and N (δ 13 C and δ 15 N) were measured during the composting of different agricultural wastes using bench-scale bioreactors. Different mixtures of agricultural wastes (horse bedding manure + legume residues; dairy manure + jatropha mill cake; dairy manure + sugarcane residues; dairy manure alone) were used for aerobic-thermophilic composting. No significant differences were found between the δ 13 C values of the feedstock and the final compost, except for dairy manure + sugarcane residues (from initial ratio of -13.6 ± 0.2 ‰ to final ratio of -14.4 ± 0.2 ‰). δ 15 N values increased significantly in composts of horse bedding manure + legumes residues (from initial ratio of +5.9 ± 0.1 ‰ to final ratio of +8.2 ± 0.5 ‰) and dairy manure + jatropha mill cake (from initial ratio of +9.5 ± 0.2 ‰ to final ratio of +12.8 ± 0.7 ‰) and was related to the total N loss (mass balance). δ 13 C can be used to differentiate composts from different feedstock (e.g. C 3 or C 4 sources). The quantitative relationship between N loss and δ 15 N variation should be determined.
[Mammals' camera-trapping in Sierra Nanchititla, Mexico: relative abundance and activity patterns].
Monroy-Vilchis, Octavio; Zarco-González, Martha M; Rodríguez-Soto, Clarita; Soria-Díaz, Leroy; Urios, Vicente
2011-03-01
Species conservation and their management depend on the availability of their population behavior and changes in time. This way, population studies include aspects such as species abundance and activity pattern, among others, with the advantage that nowadays new technologies can be applied, in addition to common methods. In this study, we used camera-traps to obtain the index of relative abundance and to establish activity pattern of medium and large mammals in Sierra Nanchititla, Mexico. The study was conducted from December 2003 to May 2006, with a total sampling effort of 4 305 trap-days. We obtained 897 photographs of 19 different species. Nasua narica, Sylvilagus floridanus and Urocyon cinereoargenteus were the most abundant, in agreement with the relative abundance index (RAI, number of independent records/100 trap-days), and according to previous studies with indirect methods in the area. The activity patterns of the species showed that 67% of them are nocturnal, except Odocoileus virginianus, Nasua narica and others. Some species showed differences with previously reported patterns, which are related with seasonality, resources availability, organism sex, principally. The applied method contributed with reliable data about relative abundance and activity patterns.
NASA Astrophysics Data System (ADS)
Ding, T.; Valkiers, S.; Kipphardt, H.; De Bièvre, P.; Taylor, P. D. P.; Gonfiantini, R.; Krouse, R.
2001-08-01
Calibrated values have been obtained for sulfur isotope abundance ratios of sulfur isotope reference materials distributed by the IAEA (Vienna). For the calibration of the measurements, a set of synthetic isotope mixtures were prepared gravimetrically from high purity Ag2S materials enriched in32S, 33S, and 34S. All materials were converted into SF6 gas and subsequently, their sulfur isotope ratios were measured on the SF5+ species using a special gas source mass spectrometer equipped with a molecular flow inlet system (IRMM's Avogadro II amount comparator). Values for the 32S/34S abundance ratios are 22.650 4(20), 22.142 4(20), and 23.393 3(17) for IAEA-S-1, IAEA-S-2, and IAEA-S-3, respectively. The calculated 32S/34S abundance ratio for V-CDT is 22.643 6(20), which is very close to the calibrated ratio obtained by Ding et al. (1999). In this way, the zero point of the VCDT scale is anchored firmly to the international system of units SI. The 32S/33S abundance ratios are 126.942(47), 125.473(55), 129.072(32), and 126.948(47) for IAEA-S-1, IAEA-S-2, IAEA-S-3, and V-CDT, respectively. In this way, the linearity of the V-CDT scale is improved over this range. The values of the sulfur molar mass for IAEA-S-1 and V-CDT were calculated to be 32.063 877(56) and 32.063 911(56), respectively, the values with the smallest combined uncertainty ever reported for the sulfur molar masses (atomic weights).
DOE Office of Scientific and Technical Information (OSTI.GOV)
Holweger, H.
1973-07-01
An analysis of 19 photospheric Si I lines whose oscillator strengths have recently been detertmined by Garz (1973) leads to a solar abundance of silicon, log epsilon /sub Si/ = 7.65 plus or minus 0.07, on the scale where log epsilon /sub H/ = 12. Together with the sodium abundance determained earlier by the same method, a solar abundance ratio /sup epsilon /Na//sup epsilon /Si = 0.045 ( plus or minus 10%) results. Within the error limits this a grees wtth the meteoritic ratio found in carbonaceous chondrites. Results concerning line-broadening by hydrogen are discussed. (auth)
NASA Technical Reports Server (NTRS)
Walker, A. B. C., Jr.; Rugge, H. R.; Weiss, K.
1974-01-01
Permitted lines in the optically thin coronal X-ray spectrum were analyzed to find the distribution of coronal material, as a function of temperature, without special assumptions concerning coronal conditions. The resonance lines of N, O, Ne, Na, Mg, Al, Si, S, and Ar which dominate the quiet coronal spectrum below 25A were observed. Coronal models were constructed and the relative abundances of these elements were determined. The intensity in the lines of the 2p-3d transitions near 15A was used in conjunction with these coronal models, with the assumption of coronal excitation, to determine the Fe XVII abundance. The relative intensities of the 2p-3d Fe XVII lines observed in the corona agreed with theoretical prediction. Using a more complete theoretical model, and higher resolution observations, a revised calculation of iron abundance relative to hydrogen of 0.000026 was made.
On the variability of alligator sex ratios
Nichols, J.D.; Chabreck, R.H.
1980-01-01
Samples of alligators from wild and 'farm' populations exhibited disproportionate sex ratios. Males predominated among young alligators from wild populations, whereas females were much more abundant than males in the farm population, where resources were superabundant. These results and other considerations lead us to hypothesize that environmental factors influence sex determination in alligators. During favorable environmental conditions natural selection is expected to favor a preponderance of the sex whose individuals exhibit the greater environmentally associated variation in relative fitness. We hypothesize that environmentally associated variation in age at sexual maturity of females produces sufficient variation in relative fitness of females to result in selection for low sex ratios during periods of resource abundance.
Lanés, L E K; Godoy, R S; Maltchik, L; Polačik, M; Blažek, R; Vrtílek, M; Reichard, M
2016-11-01
Seven ephemeral pools on the coastal plain of southern Brazil were found to be inhabited by three annual and 22 non-annual fish species. Two common annual species (Austrolebias minuano and Cynopoecilus fulgens) exhibited clear seasonal dynamics, with the appearance of young fishes in the austral autumn (May to June) and a decline in abundance over the seasonal cycle. The third annual species, Austrolebias wolterstorffii, was rare. No seasonal dynamics were observed in non-annual fishes. The relative abundance of non-annual fishes compared with annual fishes increased over the seasonal cycle, but they coexisted widely. The size structure of annual fishes suggested the presence of a single age cohort in most pools though a second age cohort was registered in one pool in August, coinciding with a large flooding. Strong sexual dimorphism in body size was found in C. fulgens throughout the seasonal cycle, while no sexual dimorphism in body size was found in A. minuano. Female-biased sex ratios were recorded in both common annual fish species in the last three sampling dates (in spring), but not during the first two sampling dates (in winter). The natural lifespan of annual fishes was <8 months. Annual fishes disappeared before habitat desiccation in half of the pools, while non-annual fishes were still present. © 2016 The Fisheries Society of the British Isles.
Muniesa, Maite; Lucena, Francisco; Blanch, Anicet R; Payán, Andrey; Jofre, Juan
2012-12-01
Water contaminated with human faeces is a risk to human health and management of water bodies can be improved by determining the sources of faecal pollution. Field studies show that existing methods are insufficient and that different markers are required. This study proposes the combined use of two microbial indicators, the concentrations of which are presented as ratios. This provides a more reliable approach to identifying faecal sources as it avoids variation due to treatment or ageing of the contamination. Among other indicators, bacteriophages have been proposed as rapid and cheap indicators of faecal pollution. Samples analysed in this study were derived from wastewater treatment plants (raw sewage, secondary and tertiary effluents and raw sewage sludge) river water, seawater and animal related wastewater. The abundance ratios of faecal coliforms and Bacteroides phages, either strain RYC2056 (non-specific for faecal origin) or strain GA17 (specific for human pollution), and among somatic coliphages and phages infecting both Bacteroides strains, were evaluated. The results indicate that the ratio of somatic coliphages and phages infecting Bacteroides strain GA17, which is specific to human faecal sources, provides a robust method for discriminating samples, even those presenting different levels and ages of pollution, and allows samples polluted with human faeces to be distinguished from those containing animal faecal pollution. This method allows the generation of numerical data that can be further applied to numerical methods for faecal pollution discrimination. Copyright © 2012 Elsevier Ltd. All rights reserved.
Solar Flare Abundances of Potassium, Argon, and Sulphur
NASA Technical Reports Server (NTRS)
Oegerle, William (Technical Monitor); Phillips, K. J. H.; Sylwester, J.; Sylwester, B.; Landi, E.
2003-01-01
The absolute coronal abundances of potassium has been determined for the first time from X-ray solar flare line and continuous spectra together with absolute and relative abundances of Ar and S. Potassium is of importance in the continuing debate concerning the nature of the coronal/photospheric element abundance ratios which are widely considered to depend on first ionization potential since it has the lowest FIP of any common element in the Sun. The measurements were obtained with the RESIK crystal spectrometer on the Coronas-F spacecraft. A differential emission measure DEM = const. x exp (-(beta)T(sub e) was found to be the most consistent with the data out of three models considered. We find that the coronal ratio [K/H] = 3.7 x 10(exp - 7), a factor 3 times photospheric, in agreement with other observations using line-to-line ratios. Our measured value for the coronal ratio [Ar/H] = 1.5 x 10(exp -6) is significantly less than photospheric, indicating that there is a slight depletion of this high-FIP element in the corona. For S (an intermediate-FIP element) we obtained [S/H] = 2.2 x 10(exp - 5), approximately the same as in previous work.
THE MYSTERIOUS CASE OF THE SOLAR ARGON ABUNDANCE NEAR SUNSPOTS IN FLARES
DOE Office of Scientific and Technical Information (OSTI.GOV)
Doschek, G. A.; Warren, H. P.
Recently we discussed an enhancement of the abundance of Ar xiv relative to Ca xiv near a sunspot during a flare, observed in spectra recorded by the Extreme-ultraviolet Imaging Spectrometer (EIS) on the Hinode spacecraft. The observed Ar xiv/Ca xiv ratio yields an argon/calcium abundance ratio seven times greater than expected from the photospheric abundance. Such a large abundance anomaly is unprecedented in the solar atmosphere. We interpreted this result as being due to an inverse first ionization potential (FIP) effect. In the published work, two lines of Ar xiv were observed, and one line was tentatively identified as anmore » Ar xi line. In this paper, we report observing a similar enhancement in a full-CCD EIS flare spectrum in 13 argon lines that lie within the EIS wavelength ranges. The observed lines include two Ar xi lines, four Ar xiii lines, six Ar xiv lines, and one Ar xv line. The enhancement is far less than reported in Doschek et al. but exhibits similar morphology. The argon abundance is close to a photospheric abundance in the enhanced area, and the abundance could be photospheric. This enhancement occurs in association with a sunspot in a small area only a few arcseconds (1″ = about 700 km) in size. There is no enhancement effect observed in the normally high-FIP sulfur and oxygen line ratios relative to lines of low-FIP elements available to EIS. Calculations of path lengths in the strongest enhanced area in Doschek et al. indicate a depletion of low-FIP elements.« less
A Comparison of Observed Abundances in Five Well-Studied Planetary Nebulae
NASA Astrophysics Data System (ADS)
Tanner, Jolene; Balick, B.; Kwitter, K. B.
2013-01-01
We have assembled data and derived abundances in several recent careful studies for five bright planetary nebulae (PNe) of low, moderate, and high ionization and relatively simple morphology. Each of the studies employ different apertures, aperture placement, and facilities for the observations. Various methods were used to derive total abundances. All used spectral windows that included [OII]3727 in the UV through Argon lines in the red. Our ultimate goal is to determine the extent to which the derived abundances are consistent. We show that the reddening-corrected line ratios are surprisingly similar despite the different modes of observation and that the various abundance analysis methods yield generally consistent results for He/H, N/H, O/H, and Ne/H (within 50% with a few larger deviations). In addition we processed the line ratios from the different sources using a common abundance derivation method (ELSA) to search for clues of systematic methodological inconsistencies. None were uncovered.
NASA Astrophysics Data System (ADS)
Lei, Zhenxin; Zhao, Gang; Zeng, Aihua; Shen, Lihua; Lan, Zhongjian; Jiang, Dengkai; Han, Zhanwen
2016-12-01
Employing tidally enhanced stellar wind, we studied in binaries the effects of metallicity, mass ratio of primary to secondary, tidal enhancement efficiency and helium abundance on the formation of blue hook (BHk) stars in globular clusters (GCs). A total of 28 sets of binary models combined with different input parameters are studied. For each set of binary model, we presented a range of initial orbital periods that is needed to produce BHk stars in binaries. All the binary models could produce BHk stars within different range of initial orbital periods. We also compared our results with the observation in the Teff-logg diagram of GC NGC 2808 and ω Cen. Most of the BHk stars in these two GCs locate well in the region predicted by our theoretical models, especially when C/N-enhanced model atmospheres are considered. We found that mass ratio of primary to secondary and tidal enhancement efficiency have little effects on the formation of BHk stars in binaries, while metallicity and helium abundance would play important roles, especially for helium abundance. Specifically, with helium abundance increasing in binary models, the space range of initial orbital periods needed to produce BHk stars becomes obviously wider, regardless of other input parameters adopted. Our results were discussed with recent observations and other theoretical models.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Pilyugin, L. S.; Grebel, E. K.; Zinchenko, I. A.
2014-12-01
The relations between oxygen abundance and disk surface brightness (OH–SB relation) in the infrared W1 band are examined for nearby late-type galaxies. The oxygen abundances were presented in Paper I. The photometric characteristics of the disks are inferred here using photometric maps from the literature through bulge-disk decomposition. We find evidence that the OH–SB relation is not unique but depends on the galactocentric distance r (taken as a fraction of the optical radius R{sub 25}) and on the properties of a galaxy: the disk scale length h and the morphological T-type. We suggest a general, four-dimensional OH–SB relation with themore » values r, h, and T as parameters. The parametric OH–SB relation reproduces the observed data better than a simple, one-parameter relation; the deviations resulting when using our parametric relation are smaller by a factor of ∼1.4 than that of the simple relation. The influence of the parameters on the OH–SB relation varies with galactocentric distance. The influence of the T-type on the OH–SB relation is negligible at the centers of galaxies and increases with galactocentric distance. In contrast, the influence of the disk scale length on the OH–SB relation is at a maximum at the centers of galaxies and decreases with galactocentric distance, disappearing at the optical edges of galaxies. Two-dimensional relations can be used to reproduce the observed data at the optical edges of the disks and at the centers of the disks. The disk scale length should be used as a second parameter in the OH–SB relation at the center of the disk while the morphological T-type should be used as a second parameter in the relation at optical edge of the disk. The relations between oxygen abundance and disk surface brightness in the optical B and infrared K bands at the center of the disk and at optical edge of the disk are also considered. The general properties of the abundance–surface brightness relations are similar for
Study on strontium isotope abundance-ratio measurements by using a 13-MeV proton beam
NASA Astrophysics Data System (ADS)
Jeong, Cheol-Ki; Jang, Han; Lee, Goung-Jin
2016-09-01
The Rb-Sr dating method is used in dating Paleozoic and Precambrian rocks. This method measures the 87Rb and the 87Sr concentrations by using thermal ionization mass spectrometry (TIMS) [J. Hefne et al., Inter. J. Phys. Sci. 3(1), 28 (2008)]. In addition, it calculates the initial 87Sr/86Sr ratio to increase the reliability of Rb-Sr dating. In this study, the 87Sr/86Sr ratio was measured by using a 13-MeV proton accelerator. Proton kinetic energies are in the range of tens of megaelectronvolts, and protons have large absorption cross-sections for ( p, n) reactions with most substances. After absorbing a proton with such a high kinetic energy, an element is converted into a nuclide with its atomic number increased by one via nuclear transmutation. These nuclides usually have short half-lives and return to the original state through radioactive decay. When a strontium sample is irradiated with protons, nuclear transmutation occurs; thus, the strontium isotope present in the sample changes to a yttrium isotope, which is an activated radioisotope. Based on this, the 87Sr/86Sr ratio was calculated by analyzing the gamma-rays emitted by each yttrium isotope. The KIRAMS-13 cyclotron at the Cyclotron Center of Chosun University, where 13-MeV protons can be extracted, was utilized in our experiment. The 87Sr/86Sr isotope ratio was computed for samples irradiated with these protons, and the result was similar to the isotope ratio for the Standard Reference Material, i.e., 98.2 ± 3.4%. As part of the analysis, proton activation analyses were performed using 13-MeV protons, and the experimental results of this research suggest a possible approach for measuring the strontium-isotope abundance ratio of samples.
Relative abundance of mesopredators and size of oak patches in the cross-timbers ecoregion
Disney, M.R.; Hellgren, E.C.; Davis, C.A.; Leslie, David M.; Engle, David M.
2008-01-01
Mesopredators (e.g., raccoon Procyon lotor, Virginia opossum Didelphis virginiana, striped skunk Mephitis mephitis) have received considerable attention because of links to population declines in birds via increased nest predation, especially in landscapes fragmented by anthropogenic forces. Relationships of abundance of mesopredators to size of habitat patches have received less attention than relationships to other metrics of fragmentation, particularly edge characteristics. We tested the hypothesis that relative abundance of mesopredators (e.g., raccoons and Virginia opossums) was related negatively to size of forest patch. We delineated 15 patches of oak (Quercus) forest ranging from 0.2 to 55.3 ha within a grassland-woodland mosaic in the cross-timbers ecoregion of Oklahoma. Scent stations and live traps within these patches were used to index relative abundance of mesopredators in summers 2003 and 2004. Both indices of relative abundance were related weakly and negatively to area of forest patch. However, rate of capture and visitation to scent station were not correlated consistently throughout the study. Our results suggested that the two methods to index abundance provided separate information on functional and numerical responses to size of patch. Our evidence that mesopredators within the cross timbers were more likely to be in smaller patches of oak forest may have implications to success of avian nesting in these patches.
Evolution of N/O ratios in galaxies from cosmological hydrodynamical simulations
NASA Astrophysics Data System (ADS)
Vincenzo, Fiorenzo; Kobayashi, Chiaki
2018-04-01
We study the redshift evolution of the gas-phase O/H and N/O abundances, both (i) for individual ISM regions within single spatially-resolved galaxies and (ii) when dealing with average abundances in the whole ISM of many unresolved galaxies. We make use of a cosmological hydrodynamical simulation including detailed chemical enrichment, which properly takes into account the variety of different stellar nucleosynthetic sources of O and N in galaxies. We identify 33 galaxies in the simulation, lying within dark matter halos with virial mass in the range 1011 ≤ MDM ≤ 1013 M⊙ and reconstruct how they evolved with redshift. For the local and global measurements, the observed increasing trend of N/O at high O/H can be explained, respectively, (i) as the consequence of metallicity gradients which have settled in the galaxy interstellar medium, where the innermost galactic regions have the highest O/H abundances and the highest N/O ratios, and (ii) as the consequence of an underlying average mass-metallicity relation that galaxies obey as they evolve across cosmic epochs, where - at any redshift - less massive galaxies have lower average O/H and N/O ratios than the more massive ones. We do not find a strong dependence on the environment. For both local and global relations, the predicted N/O-O/H relation is due to the mostly secondary origin of N in stars. We also predict that the O/H and N/O gradients in the galaxy interstellar medium gradually flatten as functions of redshift, with the average N/O ratios being strictly coupled with the galaxy star formation history. Because N production strongly depends on O abundances, we obtain a universal relation for the N/O-O/H abundance diagram whether we consider average abundances of many unresolved galaxies put together or many abundance measurements within a single spatially-resolved galaxy.
Evolution of N/O ratios in galaxies from cosmological hydrodynamical simulations
NASA Astrophysics Data System (ADS)
Vincenzo, Fiorenzo; Kobayashi, Chiaki
2018-07-01
We study the redshift evolution of the gas-phase O/H and N/O abundances, both (i) for individual interstellar medium (ISM) regions within single spatially resolved galaxies and (ii) when dealing with average abundances in the whole ISM of many unresolved galaxies. We make use of a cosmological hydrodynamical simulation including detailed chemical enrichment, which properly takes into account the variety of different stellar nucleosynthetic sources of O and N in galaxies. We identify 33 galaxies in the simulation, lying within dark matter haloes with virial mass in the range 1011 ≤ MDM ≤ 1013 M⊙ and reconstruct how they evolved with redshift. For the local and global measurements, the observed increasing trend of N/O at high O/H can be explained, respectively, (i) as the consequence of metallicity gradients that have settled in the galaxy ISM, where the innermost galactic regions have the highest O/H abundances and the highest N/O ratios, and (ii) as the consequence of an underlying average mass-metallicity relation that galaxies obey as they evolve across cosmic epochs, where - at any redshift - less massive galaxies have lower average O/H and N/O ratios than the more massive ones. We do not find a strong dependence on the environment. For both local and global relations, the predicted N/O-O/H relation is due to the mostly secondary origin of N in stars. We also predict that the O/H and N/O gradients in the galaxy ISM gradually flatten as functions of redshift, with the average N/O ratios being strictly coupled with the galaxy star formation history. Because N production strongly depends on O abundances, we obtain a universal relation for the N/O-O/H abundance diagram whether we consider average abundances of many unresolved galaxies put together or many abundance measurements within a single spatially resolved galaxy.
The solar flare iron line to continuum ratio and the coronal abundances of iron and helium
NASA Technical Reports Server (NTRS)
Mckenzie, D. L.
1975-01-01
Narrow band Ross filter measurements of the Fe 25 line flux around 0.185 nm and simultaneous broadband measurements during a solar flare were used to determine the relationship between the solar coronal abundances of iron and helium. The Fe 25 ion population was also determined as a function of time. The proportional counter and the Ross filter on OSO-7 were utilized. The data were analyzed under the separate assumptions that (1) the electron density was high enough that a single temperature could characterize the continuum spectrum and the ionization equilibrium, and that (2) the electron density was low so that the ion populations trailed the electron temperature in time. It was found that the density was at least 5x10 to the 9th power, and that the high density assumption was valid. It was also found that the iron abundance is 0.000011 for a helium abundance of 0.2, relative to hydrogen.
Cyanide and isocyanide abundances in the cold, dark cloud TMC-1
NASA Technical Reports Server (NTRS)
Irvine, W. M.; Schloerb, F. P.
1984-01-01
Cold, dark molecular clouds are particularly useful for the study of interstellar chemistry because their physical parameters are better understood than those of heterogeneous, complex giant molecular clouds. Another advantage is their relatively small distance from the solar system. The present investigaation has the objective to provide accurate abundance ratios for several cyanides and isocyanides in order to constrain models of dark cloud chemistry. The relative abundances of such related species can be particularly useful for the study of chemical processes. The cloud TMC-1 considered in the current study has a remarkably high abundance of acetylene and polyacetylene derivatives. Data at 3 mm, corresponding to the J = 1 to 0 transitions of HCN, H(C-13)N, HN(C-13), HC(N-15), and H(N-15)C were obtained.
Martin, Julien; Chamaille-Jammes, Simon; Nichols, James D.; Fritz, Herve; Hines, James E.; Fonnesbeck, Christopher J.; MacKenzie, Darryl I.; Bailey, Larissa L.
2010-01-01
The recent development of statistical models such as dynamic site occupancy models provides the opportunity to address fairly complex management and conservation problems with relatively simple models. However, surprisingly few empirical studies have simultaneously modeled habitat suitability and occupancy status of organisms over large landscapes for management purposes. Joint modeling of these components is particularly important in the context of management of wild populations, as it provides a more coherent framework to investigate the population dynamics of organisms in space and time for the application of management decision tools. We applied such an approach to the study of water hole use by African elephants in Hwange National Park, Zimbabwe. Here we show how such methodology may be implemented and derive estimates of annual transition probabilities among three dry-season states for water holes: (1) unsuitable state (dry water holes with no elephants); (2) suitable state (water hole with water) with low abundance of elephants; and (3) suitable state with high abundance of elephants. We found that annual rainfall and the number of neighboring water holes influenced the transition probabilities among these three states. Because of an increase in elephant densities in the park during the study period, we also found that transition probabilities from low abundance to high abundance states increased over time. The application of the joint habitat–occupancy models provides a coherent framework to examine how habitat suitability and factors that affect habitat suitability influence the distribution and abundance of organisms. We discuss how these simple models can further be used to apply structured decision-making tools in order to derive decisions that are optimal relative to specified management objectives. The modeling framework presented in this paper should be applicable to a wide range of existing data sets and should help to address important ecological
NASA Astrophysics Data System (ADS)
Caputo, Riccardo
2010-09-01
It is a commonplace field observation that extension fractures are more abundant than shear fractures. The questions of how much more abundant, and why, are posed in this paper and qualitative estimates of their ratio within a rock volume are made on the basis of field observations and mechanical considerations. A conceptual model is also proposed to explain the common range of ratios between extension and shear fractures, here called the j/ f ratio. The model considers three major genetic stress components originated from overburden, pore-fluid pressure and tectonics and assumes that some of the remote genetic stress components vary with time ( i.e. stress-rates are included). Other important assumptions of the numerical model are that: i) the strength of the sub-volumes is randomly attributed following a Weibull probabilistic distribution, ii) all fractures heal after a given time, thus simulating the cementation process, and therefore iii) both extensional jointing and shear fracturing could be recurrent events within the same sub-volume. As a direct consequence of these assumptions, the stress tensor at any point varies continuously in time and these variations are caused by both remote stresses and local stress drops associated with in-situ and neighbouring fracturing events. The conceptual model is implemented in a computer program to simulate layered carbonate rock bodies undergoing brittle deformation. The numerical results are obtained by varying the principal parameters, like depth ( viz. confining pressure), tensile strength, pore-fluid pressure and shape of the Weibull distribution function, in a wide range of values, therefore simulating a broad spectrum of possible mechanical and lithological conditions. The quantitative estimates of the j/ f ratio confirm the general predominance of extensional failure events during brittle deformation in shallow crustal rocks and provide useful insights for better understanding the role played by the different
Abundances in very metal-poor stars
NASA Astrophysics Data System (ADS)
Johnson, Jennifer Anne
We measured the abundances of 35 elements in 22 field red giants and a red giant in the globular cluster M92. We found the [Zn/Fe] ratio increases with decreasing [Fe/H], reaching ~0.3 at [Fe/H] = -3.0. While this is a larger [Zn/Fe] than found by previous investigators, it is not sufficient to account for the [Zn/Fe] observed in the damped Lyα systems. We test different models for the production of the s-process elements by comparing our [Y/Zr] values, which have been produced by the r- process, to predictions of what the s-process does not produce. We find that the models of Arlandini et al. (1999), which calculate s-process production in a model AGB star, agree the best. We then look at the r-process abundances across a wide range in mass. The [Y/Ba] values for most of our stars cluster around -0.30, but there are three outliers with [Y/Ba] values up to 1 dex higher. Thus the heavy element abundances do not show the same pattern from Z = 39 to Z = 56. However, our abundances ratios from Pd (Z = 46) to Yb (Z = 70) are consistent with a scaled solar system r- process pattern, arguing that at least the heavy r- process elements are made in a universal pattern. If we assume that this same pattern hold through thorium, we can determine the ages of our stars from the present abundance of radioactive thorium and an initial thorium abundance based on the abundance of stable heavy elements. Our results for five stars are consistent with those stars being the same age. Our mean age is 10.8 +/- 2 Gyr. However that result depends critically on the assumed Th/stable ratio, which we adopt from models of the r-process. For an average age of 15 Gyrs, the initial Th/Eu ratio we would need is 0.590. Finally, the [element/Fe] ratios for elements in the iron group and lower do not show any dispersion, unlike for the r- process elements such as Y and Ba. Therefore the individual contributions of supernovae have been erased for the lighter elements.
NASA Astrophysics Data System (ADS)
Ivory, J.; Steinberg, D. K.; Latour, R. J.
2016-02-01
Temporal changes in mesozooplankton community structure affect planktonic food web interactions and biogeochemical cycling. Epipelagic mesozooplankton biomass in the Sargasso Sea has increased over the last two decades, with a related increase in zooplankton-mediated carbon export. Unknown, however, is what are the patterns and variability at different temporal scales (diel, seasonal, and interannual) in abundance of each major zooplankton taxon, and how do these patterns relate to physical and other environmental changes? We enumerated major taxa of mesozooplankton collected from monthly day and night net tows in the epipelagic zone at the Bermuda Atlantic Time-series Study (BATS) site in the Sargasso Sea from 1999 to 2010. Abundances of each taxon were determined using a ZooScan optical imaging system and microscopy. Generalized Linear Models (GLMs) were used to determine what environmental parameters best explain abundance of major taxa. We used annual averages to consider broader patterns. Zooplankton taxa with the most pronounced diel vertical migration (i.e., night:day ratio, N:D, >>1) included Limacina spp. pteropods (N:D=2.02), euphausiids (1.93), calanoid copepods (1.34), and heteropods (1.34). Taxa with a pronounced spring abundance peak included chaetognaths, larvaceans, and Limacina spp. pteropods, while harpacticoid copepods peaked in late summer, and calanoid copepods in both spring and summer. Environmental variables affecting abundance differed amongst taxa. For example, calanoid copepod density was highly influenced by the abundance of a major predator- chaetognaths. Multi-year densities of calanoid copepods and ostracods both increased with increasing Water Column Stratification Index and the Atlantic Multidecadal Oscillation (AMO) index, indicating warmer sea surface temperatures are favorable for these taxa. We discuss how these temporal patterns at different scales help predict effects of global climate change on the zooplankton community.
NASA Astrophysics Data System (ADS)
Shingledecker, Christopher N.; Bergner, Jennifer B.; Le Gal, Romane; Öberg, Karin I.; Hincelin, Ugo; Herbst, Eric
2016-10-01
The chemistry of dense interstellar regions was analyzed using a time-dependent gas-grain astrochemical simulation and a new chemical network that incorporates deuterated chemistry, taking into account nuclear spin states for the hydrogen chemistry and its deuterated isotopologues. With this new network, the utility of the [HCO+]/[DCO+] abundance ratio as a probe of the cosmic-ray ionization rate has been re-examined, with special attention paid to the effect of the initial value of the ortho-to-para ratio (OPR) of molecular hydrogen. After discussing the use of the probe for cold cores, we compare our results with previous theoretical and observational results for a molecular cloud close to the supernova remnant W51C, which is thought to have an enhanced cosmic-ray ionization rate ζ caused by the nearby γ-ray source. In addition, we attempt to use our approach to estimate the cosmic-ray ionization rate for L1174, a dense core with an embedded star. Beyond the previously known sensitivity of [HCO+]/[DCO+] to ζ, we demonstrate its additional dependence on the initial OPR and, secondarily, on the age of the source, its temperature, and its density. We conclude that the usefulness of the [HCO+]/[DCO+] abundance ratio in constraining the cosmic-ray ionization rate in dense regions increases with the age of the source and the ionization rate as the ratio becomes far less sensitive to the initial value of the OPR.
Greco, Nancy M; Sánchez, Norma E; Liljesthröm, Gerardo G
2005-01-01
Neoseiulus californicus (McGregor) is a promising agent for successful Tetranychus urticae Koch control through conservation techniques, in strawberry crops in La Plata (Buenos Aires, Argentina). In prey-predator interaction, initial relative densities have an important effect on system dynamics. The economic threshold level (ETL) used for this pest in the present study was 50 active mites per leaflet. In our laboratory experiments, initial T. urticae to N. californicus ratio had a significant effect on the population abundance of T. urticae at a 7-day period. When pest/predator ratio was 5/1 (at initial pest densities from 5 to 15 females/leaflet) the final number of active T. urticae/leaflet was significantly lower than the ETL, while at 20 females/leaflet this number did not differ from the ETL. At 7.5/1 ratio, the final number of active T. urticae/leaflet, at initial pest densities from 5 to 15 females/leaflet, reached the ETL without surpassing it. At 10/1 and 15/1 ratios, pest densities exceeded the ETL only at 15 initial T. urticae/leaflet. Most greenhouse and field observations were consistent with the predictions of a graphical model based on experimental results. This predator was very effective in limiting pest densities at a 7-day period and within the range of pest-predator ratios and absolute densities used in this study. Conservation of N. californicus promoting favorable pest/predator ratios may result in early control of T. urticae.
Hyperfine Induced Transitions as Diagnostics of Low Density Plasmas and Isotopic Abundance ratios.
NASA Astrophysics Data System (ADS)
Brage, T.; Judge, P. G.; Aboussaid, A.; Godefroid, M. R.; Jonsson, P.; Leckrone, D. S.
1996-05-01
We propose a new diagnostics of isotope abundance ratios and electron densities for low density plasmas, in the form of J = 0 -> J(') = 0 radiative transitions. These are usually viewed as being allowed only through two-photon decay, but they may also be induced by the hyperfine (HPF) interaction in atomic ions. This predicts a companion line to the E1] and M2 lines in the UV0.01 multiplet of ions isoelectronic to beryllium (e.g. C III, N IV, O V and Fe XXII) or magnesium (e.g. Si II, Ca IX, Fe XV and Ni XVII). As an example the companion line to the well known lambda lambda 1906.7,1908.7 lines in C III will be at 1909.597 Angstroms, but only present in the (13) C isotope (which has nuclear spin different from zero). We present new and accurate decay rates for the nsnp (3P^oJ) -> ns(2) (1S_{J('}=0)) transitions in ions of the Be (n=2) and Mg (n=3) isoelectronic sequences. We show that the HPF induced decay rates for the J = 0 -> J(') = 0 transitions are many orders of magnitude larger than those for the competing two-photon processes and, when present, are typically one or two orders of magnitude smaller than the decay rates of the magnetic quadrupole ( J = 2-> J(') = 0) transitions for these ions. We show that several of these HPF-induced transitions are of potential astrophysical interest, in ions of C, N, Na, Mg, Al, Si, K, Cr, Fe and Ni. We highlight those cases that may be of particular diagnostic value for determining isotopic abundance ratios and/or electron densities from UV or EUV emission line data. We present our atomic data in the form of scaling laws so that, given the isotopic nuclear spin and magnetic moment, a simple expression yields estimates for HPF induced decay rates. We examine some UV solar and nebular data in the light of these new results and suggest possible cases for future study. We could not find evidence for the existence of HPF induced lines in the spectra we examined, but we demonstrate that existing data have come close to providing
NASA Astrophysics Data System (ADS)
Naafs, B. D. A.; McCormick, D.; Inglis, G. N.; Pancost, R. D.; T-GRES Peat Database Collaborators
2018-04-01
Glycerol monoalkyl glycerol tetraether lipids (GMGTs; also called 'H-GDGTs') differ from the more commonly studied glycerol dialkyl glycerol tetraether (GDGTs) in that they have an additional covalent bond that links the two alkyl chains. Six different archaeal isoprenoidal H-GDGTs (H-isoGDGTs) and one branched H-GDGT (H-brGDGT), presumably produced by bacteria, have previously been found. However, the function of H-GDGTs in both domains of life is unknown. It is thought that the formation of this additional covalent bond results in enhanced membrane stability, accounting for the high abundance of H-GDGTs in extreme environments such as geothermal settings, but so far there has been little evidence to support this hypothesis. Here we report the distribution of H-GDGTs in a global peat database (n = 471) with a broad range in mean annual air temperature (MAAT) and pH. This is the first finding of H-GDGTs in soils (specifically, peat), highlighting that H-GDGTs are widespread in mesophilic settings. In addition, we report the presence of two new H-brGDGTs with one (H-1034) and two (H-1048) additional methyl groups, respectively. Our results suggest that the relative abundance of both bacterial and archaeal H-GDGTs compared to regular GDGTs is related to temperature with the highest relative abundance of H-GDGTs in tropical peats. Although other factors besides temperature likely also play a role, these results do support the hypothesis that H-GDGTs are an adaptation to temperature to maintain membrane stability. The observation that both bacterial and archaeal membrane lipids respond to temperature indicates the same adaption across the lipid divide between these two domains of life, suggesting parallel or convergent evolution (potentially facilitated by lateral gene transfer).
Radio Bursts as Diagnostics of Relative Abundances in Solar Particles
NASA Astrophysics Data System (ADS)
Cane, H. V.; Richardson, I. G.; von Rosenvinge, T. T.
2008-05-01
Based solely on the presence of associated low frequency type III radio bursts with specific characteristics, Cane et al. (2002) suggested that large solar energetic particle events are likely to include contributions from particles accelerated in the associated flares. Studies using ACE/SIS observations of O and Fe intensity-time profiles have supported this suggestion. Nevertheless, some researchers have argued that particles cannot be flare accelerated if the relative abundances differ from those in the small particle events that are widely accepted to be composed of flare particles. However, based on the radio data, the flare particles in large events are not released at the time of the flare soft X-ray onset but are delayed, either because they are accelerated later or released later. These changed conditions are expected to alter the relative abundances (electrons to protons, heavy to light ions) compared to those associated with small flares. From a comprehensive analysis of the characteristics of the coronal mass ejections (CMEs), flares and radio bursts (at metric and longer wavelengths) associated with the ~340 proton events at >25 MeV that occurred during solar cycle 23, we confirm earlier results (Cane et al. 1986) that the timing of the type III bursts is a reasonable discriminator for the relative abundances at the start of solar particle events. In contrast, the speeds of the associated CMEs do not discriminate events, nor does the presence of meter wavelength type II bursts. Cane, H. V., R. E. McGuire, and T. T. von Rosenvinge (1986), Two classes of solar energetic particle events associated with impulsive and long-duration soft X-ray flares, Astrophys. J., 301, 448. Cane, H. V., W. C. Erickson, and N. P. Prestage (2002), Solar flares, type III radio bursts, coronal mass ejections, and energetic particles, J. Geophys. Res., 107(A10), 1315, doi:10.1029/2001JA000320.
Decline in relative abundance of bottlenose dolphins exposed to long-term disturbance.
Bejder, Lars; Samuels, Amy; Whitehead, Hal; Gales, Nick; Mann, Janet; Connor, Richard; Heithaus, Mike; Watson-Capps, Jana; Flaherty, Cindy; Krützen, Michael
2006-12-01
Studies evaluating effects of human activity on wildlife typically emphasize short-term behavioral responses from which it is difficult to infer biological significance or formulate plans to mitigate harmful impacts. Based on decades of detailed behavioral records, we evaluated long-term impacts of vessel activity on bottlenose dolphins (Tursiops sp.) in Shark Bay, Australia. We compared dolphin abundance within adjacent 36-km2 tourism and control sites, over three consecutive 4.5-year periods wherein research activity was relatively constant but tourism levels increased from zero, to one, to two dolphin-watching operators. A nonlinear logistic model demonstrated that there was no difference in dolphin abundance between periods with no tourism and periods in which one operator offered tours. As the number of tour operators increased to two, there was a significant average decline in dolphin abundance (14.9%; 95% CI=-20.8 to -8.23), approximating a decline of one per seven individuals. Concurrently, within the control site, the average increase in dolphin abundance was not significant (8.5%; 95% CI=-4.0 to +16.7). Given the substantially greater presence and proximity of tour vessels to dolphins relative to research vessels, tour-vessel activity contributed more to declining dolphin numbers within the tourism site than research vessels. Although this trend may not jeopardize the large, genetically diverse dolphin population of Shark Bay, the decline is unlikely to be sustainable for local dolphin tourism. A similar decline would be devastating for small, closed, resident, or endangered cetacean populations. The substantial effect of tour vessels on dolphin abundance in a region of low-level tourism calls into question the presumption that dolphin-watching tourism is benign.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Shields, G.A.
1976-03-01
Models of photoionized QSO emission-line regions show that measurements of O iii/N iv/C iv or N iii/C iii can yield the C/N/O ratios to an accuracy of a factor 2 or better. The N iii/C iii intensity ratios observed for the QSO PKS 1756+237 (z=1.72) implies a N/C abundance ratio 5 times larger than the solar value. This is comparable with the nitrogen overabundance in the nuclei of nearby galaxies, and it points to advanced chemical evolution in this QSO, with Zapproximately-greater-thanZ/sub sun/. Such a large abundance of nitrogen appears to be exceptional; composite spectra indicate that most QSOs havemore » (N/O) approximately one-fourth to one-half the solar value. (AIP)« less
Abundance ratios and IMF slopes in the dwarf elliptical galaxy NGC 1396 with MUSE
NASA Astrophysics Data System (ADS)
Mentz, J. J.; La Barbera, F.; Peletier, R. F.; Falcón-Barroso, J.; Lisker, T.; van de Ven, G.; Loubser, S. I.; Hilker, M.; Sánchez-Janssen, R.; Napolitano, N.; Cantiello, M.; Capaccioli, M.; Norris, M.; Paolillo, M.; Smith, R.; Beasley, M. A.; Lyubenova, M.; Munoz, R.; Puzia, T.
2016-12-01
Deep observations of the dwarf elliptical (dE) galaxy NGC 1396 (MV = -16.60, Mass ˜4 × 108 M⊙), located in the Fornax cluster, have been performed with the Very Large Telescope/Multi Unit Spectroscopic Explorer spectrograph in the wavelength region from 4750 to 9350 Å. In this paper, we present a stellar population analysis studying chemical abundances, the star formation history (SFH) and the stellar initial mass function (IMF) as a function of galactocentric distance. Different, independent ways to analyse the stellar populations result in a luminosity-weighted age of ˜6 Gyr and a metallicity [Fe/H]˜ -0.4, similar to other dEs of similar mass. We find unusually overabundant values of [Ca/Fe] ˜+ 0.1, and underabundant Sodium, with [Na/Fe] values around -0.1, while [Mg/Fe] is overabundant at all radii, increasing from ˜+ 0.1 in the centre to ˜+ 0.2 dex. We notice a significant metallicity and age gradient within this dwarf galaxy. To constrain the stellar IMF of NGC 1396, we find that the IMF of NGC 1396 is consistent with either a Kroupa-like or a top-heavy distribution, while a bottom-heavy IMF is firmly ruled out. An analysis of the abundance ratios, and a comparison with galaxies in the Local Group, shows that the chemical enrichment history of NGC 1396 is similar to the Galactic disc, with an extended SFH. This would be the case if the galaxy originated from a Large Magellanic Cloud-sized dwarf galaxy progenitor, which would lose its gas while falling into the Fornax cluster.
NASA Astrophysics Data System (ADS)
Ding, Junyan; Johnson, Edward A.; Martin, Yvonne E.
2018-03-01
The diffusive and advective erosion-created landscapes have similar structure (hillslopes and channels) across different scales regardless of variations in drivers and controls. The relative magnitude of diffusive erosion to advective erosion (D/K ratio) in a landscape development model controls hillslope length, shape, and drainage density, which regulate soil moisture variation, one of the critical resources of plants, through the contributing area (A) and local slope (S) represented by a topographic index (TI). Here we explore the theoretical relation between geomorphic processes, TI, and the abundance and distribution of plants. We derived an analytical model that expresses the TI with D, K, and A. This gives us the relation between soil moisture variation and geomorphic processes. Plant tolerance curves are used to link plant performance to soil moisture. Using the hypothetical tolerance curves of three plants, we show that the abundance and distribution of xeric, mesic, and hydric plants on the landscape are regulated by the D/K ratio. Where diffusive erosion is the major erosion process (large D/K ratio), mesic plants have higher abundance relative to xeric and hydric plants and the landscape has longer and convex-upward hillslope and low channel density. Increasing the dominance of advective erosion increases relative abundance of xeric and hydric plants dominance, and the landscape has short and concave hillslope and high channel density.
Genetic diversity in aspen and its relation to arthropod abundance
Zhang, Chunxia; Vornam, Barbara; Volmer, Katharina; Prinz, Kathleen; Kleemann, Frauke; Köhler, Lars; Polle, Andrea; Finkeldey, Reiner
2015-01-01
The ecological consequences of biodiversity have become a prominent public issue. Little is known on the effect of genetic diversity on ecosystem services. Here, a diversity experiment was established with European and North American aspen (Populus tremula, P. tremuloides) planted in plots representing either a single deme only or combinations of two, four and eight demes. The goals of this study were to explore the complex inter- and intraspecific genetic diversity of aspen and to then relate three measures for diversity (deme diversity, genetic diversity determined as Shannon index or as expected heterozygosity) to arthropod abundance. Microsatellite and AFLP markers were used to analyze the genetic variation patterns within and between the aspen demes and deme mixtures. Large differences were observed regarding the genetic diversity within demes. An analysis of molecular variance revealed that most of the total genetic diversity was found within demes, but the genetic differentiation among demes was also high. The complex patterns of genetic diversity and differentiation resulted in large differences of the genetic variation within plots. The average diversity increased from plots with only one deme to plots with two, four, and eight demes, respectively and separated plots with and without American aspen. To test whether intra- and interspecific diversity impacts on ecosystem services, arthropod abundance was determined. Increasing genetic diversity of aspen was related to increasing abundance of arthropods. However, the relationship was mainly driven by the presence of American aspen suggesting that species identity overrode the effect of intraspecific variation of European aspen. PMID:25674097
Ricotta, Carlo
2003-01-01
Traditional diversity measures such as the Shannon entropy are generally computed from the species' relative abundance vector of a given community to the exclusion of species' absolute abundances. In this paper, I first mention some examples where the total information content associated with a given community may be more adequate than Shannon's average information content for a better understanding of ecosystem functioning. Next, I propose a parametric measure of statistical information that contains both Shannon's entropy and total information content as special cases of this more general function.
Coplen, Tyler B.
2011-01-01
To minimize confusion in the expression of measurement results of stable isotope and gas-ratio measurements, recommendations based on publications of the Commission on Isotopic Abundances and Atomic Weights of the International Union of Pure and Applied Chemistry (IUPAC) are presented. Whenever feasible, entries are consistent with the Système International d'Unités, the SI (known in English as the International System of Units), and the third edition of the International Vocabulary of Basic and General Terms in Metrology (VIM, 3rd edition). The recommendations presented herein are approved by the Commission on Isotopic Abundances and Atomic Weights and are designed to clarify expression of quantities related to measurement of isotope and gas ratios to ensure that quantity equations instead of numerical value equations are used for quantity definitions. Examples of column headings consistent with quantity calculus (also called the algebra of quantities) and examples of various deprecated usages connected with the terms recommended are presented.
Lee, Won Dong; Fong, Jonathan J; Eimes, John A; Lim, Young Woon
2017-09-01
Pathogenic fungi are a growing health concern worldwide, particularly in large, densely populated cities. The dramatic upsurge of pigeon populations in cities has been implicated in the increased incidence of invasive fungal infections. In this study, we used a culture-independent, high-throughput sequencing approach to describe the diversity of clinically relevant fungi (CRF) associated with pigeon faeces and map the relative abundance of CRF across Seoul, Korea. In addition, we tested whether certain geographical, sociological and meteorological factors were significantly associated with the diversity and relative abundance of CRF. Finally, we compared the CRF diversity of fresh and old pigeon faeces to identify the source of the fungi and the role of pigeons in dispersal. Our results demonstrated that both the composition and relative abundance of CRF are unevenly distributed across Seoul. The green area ratio and the number of multiplex houses were positively correlated with species diversity, whereas wind speed and number of households were negatively correlated. The number of workers and green area ratio were positively correlated with the relative abundance of CRF, whereas wind speed was negatively correlated. Because many CRF were absent in fresh faeces, we inferred that most species cannot survive the gastrointestinal tract of pigeons and instead are likely transmitted through soil or air and use pigeon faeces as a substrate for proliferation. © 2017 John Wiley & Sons Ltd.
Abundance profiling of extremely metal-poor stars and supernova properties in the early universe
DOE Office of Scientific and Technical Information (OSTI.GOV)
Tominaga, Nozomu; Iwamoto, Nobuyuki; Nomoto, Ken'ichi, E-mail: tominaga@konan-u.ac.jp, E-mail: iwamoto.nobuyuki@jaea.go.jp, E-mail: nomoto@astron.s.u-tokyo.ac.jp
2014-04-20
After the big bang nucleosynthesis, the first heavy element enrichment in the universe was made by a supernova (SN) explosion of a population (Pop) III star (Pop III SN). The abundance ratios of elements produced from Pop III SNe are recorded in abundance patterns of extremely metal-poor (EMP) stars. The observations of the increasing number of EMP stars have made it possible to statistically constrain the explosion properties of Pop III SNe. We present Pop III SN models whose nucleosynthesis yields well reproduce, individually, the abundance patterns of 48 such metal-poor stars as [Fe/H] ≲ – 3.5. We then derivemore » relations between the abundance ratios of EMP stars and certain explosion properties of Pop III SNe: the higher [(C + N)/Fe] and [(C + N)/Mg] ratios correspond to the smaller ejected Fe mass and the larger compact remnant mass, respectively. Using these relations, the distributions of the abundance ratios of EMP stars are converted to those of the explosion properties of Pop III SNe. Such distributions are compared with those of the explosion properties of present day SNe: the distribution of the ejected Fe mass of Pop III SNe has the same peak as that of the present day SNe but shows an extended tail down to ∼10{sup –2}-10{sup –5} M {sub ☉}, and the distribution of the mass of the compact remnant of Pop III SNe is as wide as that of the present-day, stellar-mass black holes. Our results demonstrate the importance of large samples of EMP stars obtained by ongoing and future EMP star surveys and subsequent high-dispersion spectroscopic observations in clarifying the nature of Pop III SNe in the early universe.« less
Long-Term Changes in Species Composition and Relative Abundances of Sharks at a Provisioning Site
Brunnschweiler, Juerg M.; Abrantes, Kátya G.; Barnett, Adam
2014-01-01
Diving with sharks, often in combination with food baiting/provisioning, has become an important product of today’s recreational dive industry. Whereas the effects baiting/provisioning has on the behaviour and abundance of individual shark species are starting to become known, there is an almost complete lack of equivalent data from multi-species shark diving sites. In this study, changes in species composition and relative abundances were determined at the Shark Reef Marine Reserve, a multi-species shark feeding site in Fiji. Using direct observation sampling methods, eight species of sharks (bull shark Carcharhinus leucas, grey reef shark Carcharhinus amblyrhynchos, whitetip reef shark Triaenodon obesus, blacktip reef shark Carcharhinus melanopterus, tawny nurse shark Nebrius ferrugineus, silvertip shark Carcharhinus albimarginatus, sicklefin lemon shark Negaprion acutidens, and tiger shark Galeocerdo cuvier) displayed inter-annual site fidelity between 2003 and 2012. Encounter rates and/or relative abundances of some species changed over time, overall resulting in more individuals (mostly C. leucas) of fewer species being encountered on average on shark feeding dives at the end of the study period. Differences in shark community composition between the years 2004–2006 and 2007–2012 were evident, mostly because N. ferrugineus, C. albimarginatus and N. acutidens were much more abundant in 2004–2006 and very rare in the period of 2007–2012. Two explanations are offered for the observed changes in relative abundances over time, namely inter-specific interactions and operator-specific feeding protocols. Both, possibly in combination, are suggested to be important determinants of species composition and encounter rates, and relative abundances at this shark provisioning site in Fiji. This study, which includes the most species from a spatially confined shark provisioning site to date, suggests that long-term provisioning may result in competitive exclusion
Long-term changes in species composition and relative abundances of sharks at a provisioning site.
Brunnschweiler, Juerg M; Abrantes, Kátya G; Barnett, Adam
2014-01-01
Diving with sharks, often in combination with food baiting/provisioning, has become an important product of today's recreational dive industry. Whereas the effects baiting/provisioning has on the behaviour and abundance of individual shark species are starting to become known, there is an almost complete lack of equivalent data from multi-species shark diving sites. In this study, changes in species composition and relative abundances were determined at the Shark Reef Marine Reserve, a multi-species shark feeding site in Fiji. Using direct observation sampling methods, eight species of sharks (bull shark Carcharhinus leucas, grey reef shark Carcharhinus amblyrhynchos, whitetip reef shark Triaenodon obesus, blacktip reef shark Carcharhinus melanopterus, tawny nurse shark Nebrius ferrugineus, silvertip shark Carcharhinus albimarginatus, sicklefin lemon shark Negaprion acutidens, and tiger shark Galeocerdo cuvier) displayed inter-annual site fidelity between 2003 and 2012. Encounter rates and/or relative abundances of some species changed over time, overall resulting in more individuals (mostly C. leucas) of fewer species being encountered on average on shark feeding dives at the end of the study period. Differences in shark community composition between the years 2004-2006 and 2007-2012 were evident, mostly because N. ferrugineus, C. albimarginatus and N. acutidens were much more abundant in 2004-2006 and very rare in the period of 2007-2012. Two explanations are offered for the observed changes in relative abundances over time, namely inter-specific interactions and operator-specific feeding protocols. Both, possibly in combination, are suggested to be important determinants of species composition and encounter rates, and relative abundances at this shark provisioning site in Fiji. This study, which includes the most species from a spatially confined shark provisioning site to date, suggests that long-term provisioning may result in competitive exclusion among shark
Gadomski, Dena M.; Venditti, David A.; Robinson, T. Craig; Beeman, John W.; Maule, Alec G.
2004-01-01
We surveyed fish assemblages in littoral areas of Chief Joseph Reservoir of the upper Columbia River to aid in understanding this ecosystem. Fish distributions and abundances were examined during April-July 1999 in relation to environmental conditions in the reservoir. We also compared the fish assemblages in Chief Joseph reservoir in 1999 to a past study conducted during 1974-1975, and to assemblages in other areas of the Columbia River. During 67 hr of electrofishing and 78 beach seine hauls in Chief Joseph Reservoir, 7460 fishes representing 8 families were collected. The majority of the catch was native – northern pikeminnow; redside shiners; longnose, bridgelip, and largescale suckers; and sculpins. The most abundant introduced species was walleye, and one species, rainbow trout, was mostly of net-pen origin. Larger sizes of suckers and northern pikeminnow were most abundant in the upper reservoir, likely due to upstream spawning migrations. The lower reservoir contained greater abundances of smaller fishes, and this area had lower flows, smaller substrates, and more complex shorelines that offered these fishes refugia. Only adult suckers displayed significant differences in abundances related to substrate. The relative abundances of species appeared to have changed since the 1970s, when the dominant fishes were northern pikeminnow, peamouth, largescale suckers, and walleye. Fish assemblage differences between Chief Joseph Reservoir and lower Columbia River reservoirs were also evident due to the morphology of the reservoir, its more northerly location, and the lack of fish passage facilities at Chief Joseph Dam. Our study is one of the few descriptions of fishes in the upper Columbia Rivers.
A TiO2 abundance map for the northern maria
NASA Technical Reports Server (NTRS)
Johnson, T. V.; Saunders, R. S.; Matson, D. L.; Mosher, J. A.
1977-01-01
A map of TiO2 abundance for most of the northern maria is presented. The telescopic data base used is the 0.38/0.56-micron ratio mosaic from Johnson et at. (1977). The titanium content has been estimated using the correlation established by Charette et al. (1974). The combination of observational, processing, and calibration errors indicates that the TiO2 map is accurate to + or - 2% (wt% TiO2) for high TiO2 content (more than 5%) and + or - 1% for low values of TiO2. Analysis of the lunar sample and telescopic data suggests strongly that the spectral parameter mapped is sensitive primarily to TiO2 abundance in the range 3-9% and does not correlate directly with iron content. It is suggested, however, that for the low TiO2 mare regions (less than 2-3% TiO2) there may be a relation between the spectral ratio and iron content and that some of the reddest mare areas in the Imbrium region may have low iron contents as well as low titanium abundances.
System and method for high precision isotope ratio destructive analysis
Bushaw, Bruce A; Anheier, Norman C; Phillips, Jon R
2013-07-02
A system and process are disclosed that provide high accuracy and high precision destructive analysis measurements for isotope ratio determination of relative isotope abundance distributions in liquids, solids, and particulate samples. The invention utilizes a collinear probe beam to interrogate a laser ablated plume. This invention provides enhanced single-shot detection sensitivity approaching the femtogram range, and isotope ratios that can be determined at approximately 1% or better precision and accuracy (relative standard deviation).
Ellis, Vincenzo A; Medeiros, Matthew C I; Collins, Michael D; Sari, Eloisa H R; Coffey, Elyse D; Dickerson, Rebecca C; Lugarini, Camile; Stratford, Jeffrey A; Henry, Donata R; Merrill, Loren; Matthews, Alix E; Hanson, Alison A; Roberts, Jackson R; Joyce, Michael; Kunkel, Melanie R; Ricklefs, Robert E
2017-01-01
Parasite prevalence is thought to be positively related to host population density owing to enhanced contagion. However, the relationship between prevalence and local abundance of multiple host species is underexplored. We surveyed birds and their haemosporidian parasites (genera Plasmodium and Haemoproteus) at multiple sites across eastern North America to test whether the prevalence of these parasites in a host species at a particular site is related to that host's local abundance. Prevalence was positively related to host abundance within most sites, although the effect was stronger and more consistent for Plasmodium than for Haemoproteus. In contrast, prevalence was not related to variation in the abundance of most individual host species among sites across the region. These results suggest that parasite prevalence partly reflects the relative abundances of host species in local assemblages. However, three nonnative host species had low prevalence despite being relatively abundant at one site, as predicted by the enemy release hypothesis.
NASA Technical Reports Server (NTRS)
Newsom, H. E.; White, W. M.; Jochum, K. P.; Hofmann, A. W.
1986-01-01
The hypothesis that the mantle Pb isotope ratios reflect continued extraction of Pb into the earth's core over geologic time is evaluated by studying the depeletion of chalcophile and siderophile elements in the mantle. Oceanic basalt samples are analyzed in order to determine the Pb, Sr, and Nd isotropic compositions and the abundances of siderophile and chalcophile elements and incompatible lithophile elements. The data reveal that there is no systematic variation of siderophile or chalcophile element abundances relative to abundances of lithophile elements and the Pb/Ce ratio of the mantle is constant. It is suggested that the crust formation involves nonmagmatic and magmatic processes.
Huber, Edith; Bell, Tina L; Adams, Mark A
2013-11-01
This before-and-after-impact study uses the natural abundance N isotope ratio (δ(15)N) to investigate the effects of a wildfire on sub-alpine ecosystem properties and processes. We measured the (15)N signatures of soil, charred organic material, ash and foliage in three sub-alpine plant communities (grassland, heathland and woodland) in south-eastern Australia. Surface bulk soil was temporarily enriched in (15)N immediately after wildfire compared to charred organic material and ash in all plant communities. We associated the enrichment of bulk soil with fractionation of N during combustion and volatilization of N, a process that also explains the sequential enrichment of (15)N of unburnt leaves > ash > charred organic material in relation to duration and intensity of heating. The rapid decline in (15)N of bulk soil to pre-fire values indicates that depleted ash, containing considerable amounts of total N, was readily incorporated into the soil. Foliar δ(15)N also increased with values peaking 1 year post-fire. Foliar enrichment was foremost coupled with the release of enriched NH4(+) into the soil owing to isotopic discrimination during volatilization of soluble N and combustion of organic material. The mode of post-fire regeneration influenced foliar (15)N enrichment in two species indicating use of different sources of N following fire. The use of natural abundance of (15)N in soil, ash and foliage as a means of tracing transformation of N during wildfire has established the importance of combustion products as an important, albeit temporary source of inorganic N for plants regenerating after wildfire.
Lunar phase function effects on spectral ratios used for resource assessment
NASA Technical Reports Server (NTRS)
Larson, S. M.; Collins, J.; Singer, R. B.; Johnson, J. R.; Melendrez, D. E.
1993-01-01
Groundbased telescopic CCD images of 36 selected locations on the moon were obtained in five 'standard' bandpasses at 12 phase angles ranging from -78 deg to +75 deg to measure phase function effects on the ratio values used to quantify the abundance of TiO2 and qualitatively indicate soil maturity. Consistent with previous studies, we find that the moon is 'bluer' at small phase angles, but that the effect on the ratio values for TiO2 abundance for the phase angles of our data is on the order of the measurement uncertainties throughout the range of abundances found in the mare. The effect is more significant as seen from orbiting spacecraft over a range of selenographic latitude. Spectral ratio images (400/560 and 400/730 nm) were used to map the abundance of TiO2 using the empirical relation found by Charlette et al from analysis of returned lunar soils. Additionally, the 950/560 and 950/730 nm image ratios were used to define the regions of mature mare soil in which the relation is valid. Although the phase function dependence on wavelength was investigated and quantified for small areas and the integrated disc, the effect specifically on TiO2 mapping was not rigorously determined. For consistency and convenience in observing the whole lunar front side, our mapping utilized images taken -15 deg less than alpha less than 15 deg when the moon was fully illuminated from earth; however, this includes the strong opposition peak.
Guo, Guangyu; Li, Ning
2011-07-01
In the quantitative proteomic studies, numerous in vitro and in vivo peptide labeling strategies have been successfully applied to measure differentially regulated protein and peptide abundance. These approaches have been proven to be versatile and repeatable in biological discoveries. (15)N metabolic labeling is one of these widely adopted and economical methods. However, due to the differential incorporation rates of (15)N or (14)N, the labeling results produce imperfectly matched isotopic envelopes between the heavy and light nitrogen-labeled peptides. In the present study, we have modified the solid Arabidopsis growth medium to standardize the (15)N supply, which led to a uniform incorporation of (15)N into the whole plant protein complement. The incorporation rate (97.43±0.11%) of (15)N into (15)N-coded peptides was determined by correlating the intensities of peptide ions with the labeling efficiencies according to Gaussian distribution. The resulting actual incorporation rate (97.44%) and natural abundance of (15)N/(14)N-coded peptides are used to re-calculate the intensities of isotopic envelopes of differentially labeled peptides, respectively. A modified (15)N/(14)N stable isotope labeling strategy, SILIA, is assessed and the results demonstrate that this approach is able to differentiate the fold change in protein abundance down to 10%. The machine dynamic range limitation and purification step will make the precursor ion ratio deriving from the actual ratio fold change. It is suggested that the differentially mixed (15)N-coded and (14)N-coded plant protein samples that are used to establish the protein abundance standard curve should be prepared following a similar protein isolation protocol used to isolate the proteins to be quantitated. Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.
DIRECT DETERMINATION OF THE HF/H{sub 2} ABUNDANCE RATIO IN INTERSTELLAR GAS
DOE Office of Scientific and Technical Information (OSTI.GOV)
Indriolo, Nick; Neufeld, D. A.; Seifahrt, A.
2013-02-20
We report the first detection of the v = 1-0, R(0) ro-vibrational transition of HF at 2.499385 {mu}m arising from interstellar gas. The line is seen in absorption toward three background sources-HD 154368, Elias 29, and AFGL 2136 IRS 1-all of which have reported H{sub 2} column densities determined from observations of H{sub 2}. This allows for the first direct determination of the HF/H{sub 2} abundance ratio. We find values of N(HF)/N(H{sub 2}) = 1.15 Multiplication-Sign 10{sup -8} and 0.69 Multiplication-Sign 10{sup -8} for HD 154368 and Elias 29, respectively. The sight line toward AFGL 2136 IRS 1 also showsmore » absorption from the v = 1-0, R(1) transition of HF, indicating warm, dense (n {sub H} {approx}> 10{sup 9} cm{sup -3}) gas, likely very close to the central protostar. Ascribing portions of the HF absorption to warm and cold gas, we find N(HF)/N(H{sub 2}) = (1.7-2.9) Multiplication-Sign 10{sup -8} and (0.33-0.58) Multiplication-Sign 10{sup -8} for the two components, respectively. Except for the warm component toward AFGL 2136 IRS 1, all observed HF/H{sub 2} ratios are well below N(HF)/N(H{sub 2}) = 3.6 Multiplication-Sign 10{sup -8}, the value predicted if nearly all gas phase fluorine is in the form of HF. Models of fluorine chemistry that account for depletion onto grains are able to reproduce the results toward HD 154368, but not in the cold, dense gas toward AFGL 2136 IRS 1 and Elias 29. Most likely, some combinations of simplifying assumptions made in the chemical models are responsible for these discrepancies.« less
Bolduc, F.; Afton, A.D.
2008-01-01
Wetland use by waterbirds is highly dependent on water depth, and depth requirements generally vary among species. Furthermore, water depth within wetlands often varies greatly over time due to unpredictable hydrological events, making comparisons of waterbird abundance among wetlands difficult as effects of habitat variables and water depth are confounded. Species-specific relationships between bird abundance and water depth necessarily are non-linear; thus, we developed a methodology to correct waterbird abundance for variation in water depth, based on the non-parametric regression of these two variables. Accordingly, we used the difference between observed and predicted abundances from non-parametric regression (analogous to parametric residuals) as an estimate of bird abundance at equivalent water depths. We scaled this difference to levels of observed and predicted abundances using the formula: ((observed - predicted abundance)/(observed + predicted abundance)) ?? 100. This estimate also corresponds to the observed:predicted abundance ratio, which allows easy interpretation of results. We illustrated this methodology using two hypothetical species that differed in water depth and wetland preferences. Comparisons of wetlands, using both observed and relative corrected abundances, indicated that relative corrected abundance adequately separates the effect of water depth from the effect of wetlands. ?? 2008 Elsevier B.V.
Fear or food - abundance of red fox in relation to occurrence of lynx and wolf.
Wikenros, Camilla; Aronsson, Malin; Liberg, Olof; Jarnemo, Anders; Hansson, Jessica; Wallgren, Märtha; Sand, Håkan; Bergström, Roger
2017-08-22
Apex predators may affect mesopredators through intraguild predation and/or supply of carrion from their prey, causing a trade-off between avoidance and attractiveness. We used wildlife triangle snow-tracking data to investigate the abundance of red fox (Vulpes vulpes) in relation to lynx (Lynx lynx) and wolf (Canis lupus) occurrence as well as land composition and vole (Microtus spp.) density. Data from the Swedish wolf-monitoring system and VHF/GPS-collared wolves were used to study the effect of wolf pack size and time since wolf territory establishment on fox abundance. Bottom-up processes were more influential than top-down effects as the proportion of arable land was the key indicator of fox abundance at the landscape level. At this spatial scale, there was no effect of wolf abundance on fox abundance, whereas lynx abundance had a positive effect. In contrast, at the wolf territory level there was a negative effect of wolves on fox abundance when including detailed information of pack size and time since territory establishment, whereas there was no effect of lynx abundance. This study shows that different apex predator species may affect mesopredator abundance in different ways and that the results may be dependent on the spatiotemporal scale and resolution of the data.
Ngonyoka, Anibariki; Gwakisa, Paul S; Estes, Anna B; Nnko, Happiness J; Hudson, Peter J; Cattadori, Isabella M
2017-06-01
Human activities modify ecosystem structure and function and can also alter the vital rates of vectors and thus the risk of infection with vector-borne diseases. In the Maasai Steppe ecosystem of northern Tanzania, local communities depend on livestock and suitable pasture that is shared with wildlife, which can increase tsetse abundance and the risk of trypanosomiasis. We monitored the monthly tsetse fly abundance adjacent to Tarangire National Park in 2014-2015 using geo-referenced, baited epsilon traps. We examined the effect of habitat types and vegetation greenness (NDVI) on the relative abundance of tsetse fly species. Host availability (livestock and wildlife) was also recorded within 100×100 m of each trap site. The highest tsetse abundance was found in the ecotone between Acacia-Commiphora woodland and grassland, and the lowest in riverine woodland. Glossina swynnertoni was the most abundant species (68%) trapped throughout the entire study, while G. pallidipes was the least common (4%). Relative species abundance was negatively associated with NDVI, with greatest abundance observed in the dry season. The relationship with the abundance of wildlife and livestock was more complex, as we found positive and negative associations depending on the host and fly species. While habitat is important for tsetse distribution, hosts also play a critical role in affecting fly abundance and, potentially, trypanosomiasis risk. © 2017 The Society for Vector Ecology.
Negative plant-soil feedback predicts tree-species relative abundance in a tropical forest.
Mangan, Scott A; Schnitzer, Stefan A; Herre, Edward A; Mack, Keenan M L; Valencia, Mariana C; Sanchez, Evelyn I; Bever, James D
2010-08-05
The accumulation of species-specific enemies around adults is hypothesized to maintain plant diversity by limiting the recruitment of conspecific seedlings relative to heterospecific seedlings. Although previous studies in forested ecosystems have documented patterns consistent with the process of negative feedback, these studies are unable to address which classes of enemies (for example, pathogens, invertebrates, mammals) exhibit species-specific effects strong enough to generate negative feedback, and whether negative feedback at the level of the individual tree is sufficient to influence community-wide forest composition. Here we use fully reciprocal shade-house and field experiments to test whether the performance of conspecific tree seedlings (relative to heterospecific seedlings) is reduced when grown in the presence of enemies associated with adult trees. Both experiments provide strong evidence for negative plant-soil feedback mediated by soil biota. In contrast, above-ground enemies (mammals, foliar herbivores and foliar pathogens) contributed little to negative feedback observed in the field. In both experiments, we found that tree species that showed stronger negative feedback were less common as adults in the forest community, indicating that susceptibility to soil biota may determine species relative abundance in these tropical forests. Finally, our simulation models confirm that the strength of local negative feedback that we measured is sufficient to produce the observed community-wide patterns in tree-species relative abundance. Our findings indicate that plant-soil feedback is an important mechanism that can maintain species diversity and explain patterns of tree-species relative abundance in tropical forests.
The relative contribution of climate to changes in lesser prairie-chicken abundance
Ross, Beth E.; Haukos, David A.; Hagen, Christian A.; Pitman, James
2016-01-01
Managing for species using current weather patterns fails to incorporate the uncertainty associated with future climatic conditions; without incorporating potential changes in climate into conservation strategies, management and conservation efforts may fall short or waste valuable resources. Understanding the effects of climate change on species in the Great Plains of North America is especially important, as this region is projected to experience an increased magnitude of climate change. Of particular ecological and conservation interest is the lesser prairie-chicken (Tympanuchus pallidicinctus), which was listed as “threatened” under the U.S. Endangered Species Act in May 2014. We used Bayesian hierarchical models to quantify the effects of extreme climatic events (extreme values of the Palmer Drought Severity Index [PDSI]) relative to intermediate (changes in El Niño Southern Oscillation) and long-term climate variability (changes in the Pacific Decadal Oscillation) on trends in lesser prairie-chicken abundance from 1981 to 2014. Our results indicate that lesser prairie-chicken abundance on leks responded to environmental conditions of the year previous by positively responding to wet springs (high PDSI) and negatively to years with hot, dry summers (low PDSI), but had little response to variation in the El Niño Southern Oscillation and the Pacific Decadal Oscillation. Additionally, greater variation in abundance on leks was explained by variation in site relative to broad-scale climatic indices. Consequently, lesser prairie-chicken abundance on leks in Kansas is more strongly influenced by extreme drought events during summer than other climatic conditions, which may have negative consequences for the population as drought conditions intensify throughout the Great Plains.
C/O ratios of stars with transiting hot Jupiter exoplanets ,
DOE Office of Scientific and Technical Information (OSTI.GOV)
Teske, Johanna K.; Cunha, Katia; Smith, Verne V.
The relative abundances of carbon and oxygen have long been recognized as fundamental diagnostics of stellar chemical evolution. Now, the growing number of exoplanet observations enable estimation of these elements in exoplanetary atmospheres. In hot Jupiters, the C/O ratio affects the partitioning of carbon in the major observable molecules, making these elements diagnostic of temperature structure and composition. Here we present measurements of carbon and oxygen abundances in 16 stars that host transiting hot Jupiter exoplanets, and we compare our C/O ratios to those measured in larger samples of host stars, as well as those estimated for the corresponding exoplanetmore » atmospheres. With standard stellar abundance analysis we derive stellar parameters as well as [C/H] and [O/H] from multiple abundance indicators, including synthesis fitting of the [O I] λ6300 line and non-LTE corrections for the O I triplet. Our results, in agreement with recent suggestions, indicate that previously measured exoplanet host star C/O ratios may have been overestimated. The mean transiting exoplanet host star C/O ratio from this sample is 0.54 (C/O{sub ☉} = 0.54), versus previously measured C/O{sub host} {sub star} means of ∼0.65-0.75. We also observe the increase in C/O with [Fe/H] expected for all stars based on Galactic chemical evolution; a linear fit to our results falls slightly below that of other exoplanet host star studies but has a similar slope. Though the C/O ratios of even the most-observed exoplanets are still uncertain, the more precise abundance analysis possible right now for their host stars can help constrain these planets' formation environments and current compositions.« less
NASA Technical Reports Server (NTRS)
Webster, Christopher R.; Mahaffy, Paul R.
2011-01-01
Understanding the origin of Martian methane will require numerous complementary measurements from both in situ and remote sensing investigations and laboratory work to correlate planetary surface geophysics with atmospheric dynamics and chemistry. Three instruments (Quadrupole Mass Spectrometer (QMS), Gas Chromatograph (GC) and Tunable Laser Spectrometer (TLS)) with sophisticated sample handling and processing capability make up the Sample Analysis at Mars (SAM) analytical chemistry suite on NASA s 2011 Mars Science Laboratory (MSL) Mission. Leveraging off the SAM sample and gas processing capability that includes methane enrichment, TLS has unprecedented sensitivity for measuring absolute methane (parts-per-trillion), water, and carbon dioxide abundances in both the Martian atmosphere and evolved from heated soil samples. In concert with a wide variety of associated trace gases (e.g. SO2, H2S, NH3, higher hydrocarbons, organics, etc.) and other isotope ratios measured by SAM, TLS will focus on determining the absolute abundances of methane, water and carbon dioxide, and their isotope ratios: 13C/12C and D/H in methane; 13C/12C and 18O/17O/16O in carbon dioxide; and 18O/17O/16O and D/H in water. Measurements near the MSL landing site will be correlated with satellite (Mars Express, Mars 2016) and ground-based observations.
Huang, Qiongyu; Sauer, John R; Dubayah, Ralph O
2017-09-01
Shifts in species distributions are major fingerprint of climate change. Examining changes in species abundance structures at a continental scale enables robust evaluation of climate change influences, but few studies have conducted these evaluations due to limited data and methodological constraints. In this study, we estimate temporal changes in abundance from North American Breeding Bird Survey data at the scale of physiographic strata to examine the relative influence of different components of climatic factors and evaluate the hypothesis that shifting species distributions are multidirectional in resident bird species in North America. We quantify the direction and velocity of the abundance shifts of 57 permanent resident birds over 44 years using a centroid analysis. For species with significant abundance shifts in the centroid analysis, we conduct a more intensive correlative analysis to identify climate components most strongly associated with composite change of abundance within strata. Our analysis focus on two contrasts: the relative importance of climate extremes vs. averages, and of temperature vs. precipitation in strength of association with abundance change. Our study shows that 36 species had significant abundance shifts over the study period. The average velocity of the centroid is 5.89 km·yr -1 . The shifted distance on average covers 259 km, 9% of range extent. Our results strongly suggest that the climate change fingerprint in studied avian distributions is multidirectional. Among 6 directions with significant abundance shifts, the northwestward shift was observed in the largest number of species (n = 13). The temperature/average climate model consistently has greater predictive ability than the precipitation/extreme climate model in explaining strata-level abundance change. Our study shows heterogeneous avian responses to recent environmental changes. It highlights needs for more species-specific approaches to examine contributing
Begon, Mike; Diggle, Peter J.; Serrano, Soledad; Reis, Mitermayer G.; Childs, James E.; Ko, Albert I.; Costa, Federico
2016-01-01
Norway rats (Rattus norvegicus) living in urban environments are a critical public health and economic problem, particularly in urban slums where residents are at a higher risk for rat borne diseases, yet convenient methods to quantitatively assess population sizes are lacking. We evaluated track plates as a method to determine rat distribution and relative abundance in a complex urban slum environment by correlating the presence and intensity of rat-specific marks on track plates with findings from rat infestation surveys and trapping of rats to population exhaustion. To integrate the zero-inflated track plate data we developed a two-component mixture model with one binary and one censored continuous component. Track plate mark-intensity was highly correlated with signs of rodent infestation (all coefficients between 0.61 and 0.79 and all p-values < 0.05). Moreover, the mean level of pre-trapping rat-mark intensity on plates was significantly associated with the number of rats captured subsequently (Odds ratio1.38; 95% CI 1.19-1.61) and declined significantly following trapping (Odds ratio 0.86; 95% CI 0.78-0.95). Track plates provided robust proxy measurements of rat abundance and distribution and detected rat presence even when populations appeared ‘trapped out’. Tracking plates are relatively easy and inexpensive methods that can be used to intensively sample settings such as urban slums, where traditional trapping or mark-recapture studies are impossible to implement, and therefore the results can inform and assess the impact of targeted urban rodent control campaigns. PMID:27453682
Weed management practices affect the diversity and relative abundance of physic nut mites.
Saraiva, Althiéris de Sousa; Sarmento, Renato A; Erasmo, Eduardo A L; Pedro-Neto, Marçal; de Souza, Danival José; Teodoro, Adenir V; Silva, Daniella G
2015-03-01
Crop management practices determine weed community, which in turn may influence patterns of diversity and abundance of associated arthropods. This study aimed to evaluate whether local weed management practices influence the diversity and relative abundance of phytophagous and predatory mites, as well as mites with undefined feeding habits--of the families Oribatidae and Acaridae--in a physic nut (Jatropha curcas L.) plantation subjected to (1) within-row herbicide spraying and between-row mowing; (2) within-row herbicide spraying and no between-row mowing; (3) within-row weeding and between-row mowing; (4) within-row weeding and no between-row mowing; and (5) unmanaged (control). The herbicide used was glyphosate. Herbicide treatments resulted in higher diversity and relative abundance of predatory mites and mites with undefined feeding habit on physic nut shrubs. This was probably due to the toxic effects of the herbicide on mites or to removal of weeds. Within-row herbicide spraying combined with between-row mowing was the treatment that most contributed to this effect. Our results show that within-row weeds harbor important species of predatory mites and mites with undefined feeding habit. However, the dynamics of such mites in the system can be changed according to the weed management practice applied. Among the predatory mites of the family Phytoseiidae Amblydromalus sp. was the most abundant, whereas Brevipalpus phoenicis was the most frequent phytophagous mite and an unidentified oribatid species was the most frequent mite with undefined feeding habit.
Energetic-particle abundances in impulsive solar flares
NASA Technical Reports Server (NTRS)
Reames, D. V.; Cane, H. V.; Von Rosenvinge, T. T.
1990-01-01
The abundances of elements and of He-3 in 90 solar electron events have been examined. It is found that the events fall into two distinct groups based upon their F/C ratio. Events in the F-rich group frequently have high He-3/He-4 ratios and are associated with type III and type V radio bursts in the parent flare. The F-poor events are associated with type IV bursts. These results on individual events support the conclusions of earlier work done with daily-averaged abundances.
Chemical Abundance Analysis of Moving Group W11450 (Latham 1)
NASA Astrophysics Data System (ADS)
O'Connell, Julia E.; Martens, Kylee; Frinchaboy, Peter M.
2016-12-01
We present elemental abundances for all seven stars in Moving Group W11450 (Latham 1) to determine if they may be chemically related. These stars appear to be both spatially and kinematically related, but no spectroscopic abundance analysis exists in literature. Abundances for eight elements were derived via equivalent width analyses of high-resolution (R ˜ 60,000), high-signal-to-noise ratio (< {{S}}/{{N}}> ˜ 100) spectra obtained with the Otto Struve 2.1 m telescope and the Sandiford Echelle Spectrograph at McDonald Observatory. The large star-to-star scatter in metallicity, -0.55 ≤ [Fe/H] ≤slant 0.06 dex (σ = 0.25), implies these stars were not produced from the same chemically homogeneous molecular cloud, and are therefore not part of a remnant or open cluster as previously proposed. Prior to this analysis, it was suggested that two stars in the group, W11449 and W11450, are possible wide binaries. The candidate wide binary pair show similar chemical abundance patterns with not only iron but with other elements analyzed in this study, suggesting the proposed connection between these two stars may be real.
Elemental abundance differences between nuclei acclerated in CIR shocks and solar flares
NASA Technical Reports Server (NTRS)
Dietrich, W. F.; Simpson, J. A.
1985-01-01
Measurement of the ratios of nuclear abundances H/He, CNO/Fe-group and the Fe-group/HE for 51 passages of Corotating Interaction Regions (CIRs) at 1 AU, and measurement of these ratios from 620 solar flares in the energy range 0.6 to 4 MeV per nucleon, show that CIR shock acceleration alone does not change significantly these ratios from the values they have for solar system abundances or the solar wind. The solar flare ratios continue to reflect strong biases in the abundances, consistent with requirements for multistage acceleration rpocesses at the Sun.
Traffic-Related Air Pollution, Blood Pressure, and Adaptive Response of Mitochondrial Abundance.
Zhong, Jia; Cayir, Akin; Trevisi, Letizia; Sanchez-Guerra, Marco; Lin, Xinyi; Peng, Cheng; Bind, Marie-Abèle; Prada, Diddier; Laue, Hannah; Brennan, Kasey J M; Dereix, Alexandra; Sparrow, David; Vokonas, Pantel; Schwartz, Joel; Baccarelli, Andrea A
2016-01-26
Exposure to black carbon (BC), a tracer of vehicular-traffic pollution, is associated with increased blood pressure (BP). Identifying biological factors that attenuate BC effects on BP can inform prevention. We evaluated the role of mitochondrial abundance, an adaptive mechanism compensating for cellular-redox imbalance, in the BC-BP relationship. At ≥ 1 visits among 675 older men from the Normative Aging Study (observations=1252), we assessed daily BP and ambient BC levels from a stationary monitor. To determine blood mitochondrial abundance, we used whole blood to analyze mitochondrial-to-nuclear DNA ratio (mtDNA/nDNA) using quantitative polymerase chain reaction. Every standard deviation increase in the 28-day BC moving average was associated with 1.97 mm Hg (95% confidence interval [CI], 1.23-2.72; P<0.0001) and 3.46 mm Hg (95% CI, 2.06-4.87; P<0.0001) higher diastolic and systolic BP, respectively. Positive BC-BP associations existed throughout all time windows. BC moving averages (5-day to 28-day) were associated with increased mtDNA/nDNA; every standard deviation increase in 28-day BC moving average was associated with 0.12 standard deviation (95% CI, 0.03-0.20; P=0.007) higher mtDNA/nDNA. High mtDNA/nDNA significantly attenuated the BC-systolic BP association throughout all time windows. The estimated effect of 28-day BC moving average on systolic BP was 1.95-fold larger for individuals at the lowest mtDNA/nDNA quartile midpoint (4.68 mm Hg; 95% CI, 3.03-6.33; P<0.0001), in comparison with the top quartile midpoint (2.40 mm Hg; 95% CI, 0.81-3.99; P=0.003). In older adults, short-term to moderate-term ambient BC levels were associated with increased BP and blood mitochondrial abundance. Our findings indicate that increased blood mitochondrial abundance is a compensatory response and attenuates the cardiac effects of BC. © 2015 American Heart Association, Inc.
Interstellar Abundances Toward X Per, Revisited
NASA Technical Reports Server (NTRS)
Valencic, Lynne A.; Smith, Randall K.
2014-01-01
The nearby X-ray binary X Per (HD 24534) provides a useful beacon with which to measure elemental abundances in the local ISM. We examine absorption features of 0, Mg, and Si along this line of sight using spectra from the Chandra Observatory's LETG/ ACIS-S and XMM-Newton's RGS instruments. In general, we find that the abundances and their ratios are similar to those of young F and G stars and the most recent solar values. We compare our results with abundances required by dust grain models.
Interstellar Abundances Toward X Per, Revisited
NASA Technical Reports Server (NTRS)
Valencic, Lynne A.; Smith, Randall K.
2012-01-01
The nearby X-ray binary X Per (HD 24534) provides a useful beacon with which to measure elemental abundances in the local ISM. We examine absorption features of O, Mg, and Si along this line of sight using spectra from the Chandra Observatory's LETG/ACIS-S and XMM-Newton's RGS instruments. In general, we find that the abundances and their ratios are similar to those of young F and G stars and the most recent solar values. We compare our results with abundances required by dust grain models.
Loziuk, Philip L.; Sederoff, Ronald R.; Chiang, Vincent L.; Muddiman, David C.
2014-01-01
Quantitative mass spectrometry has become central to the field of proteomics and metabolomics. Selected reaction monitoring is a widely used method for the absolute quantification of proteins and metabolites. This method renders high specificity using several product ions measured simultaneously. With growing interest in quantification of molecular species in complex biological samples, confident identification and quantitation has been of particular concern. A method to confirm purity or contamination of product ion spectra has become necessary for achieving accurate and precise quantification. Ion abundance ratio assessments were introduced to alleviate some of these issues. Ion abundance ratios are based on the consistent relative abundance (RA) of specific product ions with respect to the total abundance of all product ions. To date, no standardized method of implementing ion abundance ratios has been established. Thresholds by which product ion contamination is confirmed vary widely and are often arbitrary. This study sought to establish criteria by which the relative abundance of product ions can be evaluated in an absolute quantification experiment. These findings suggest that evaluation of the absolute ion abundance for any given transition is necessary in order to effectively implement RA thresholds. Overall, the variation of the RA value was observed to be relatively constant beyond an absolute threshold ion abundance. Finally, these RA values were observed to fluctuate significantly over a 3 year period, suggesting that these values should be assessed as close as possible to the time at which data is collected for quantification. PMID:25154770
Zaccone, R; Boldrin, A; Caruso, G; La Ferla, R; Maimone, G; Santinelli, C; Turchetto, M
2012-07-01
The distribution of extracellular enzymatic activities (EEA) [leucine aminopeptidase (LAP), ß-glucosidase (GLU), alkaline phosphatase (AP)], as well as that of prokaryotic abundance (PA) and biomass (PB), dissolved organic carbon (DOC), particulate organic carbon and particulate total nitrogen (POC, PTN), was determined in the epi-, meso-, and bathypelagic waters of the Mediterranean Sea along a West-East transect and at one Atlantic station located outside the Strait of Gibraltar. This study represents a synoptical evaluation of the microbial metabolism during early summer. Decreasing trends with depth were observed for most of the parameters (PA, PB, AP, DOC, POC, PTN). Significant differences between the western and eastern basins of the Mediterranean Sea were found, displaying higher rates of LAP and GLU and lower C/N ratios more in the eastern than in the western areas. Conversely, in the epipelagic layer, PA and PB were found to be higher in the western than in the eastern basins. PB was significantly related to DOC concentration (all data, n = 145, r = 0.53, P < 0.01), while significant correlations of EEA with POC and PTN were found in the epipelagic layer, indicating an active response of microbial metabolism to organic substrates. Specific enzyme activities normalized to cell abundance pointed out high values of LAP and GLU in the bathypelagic layer, especially in the eastern basin, while cell-specific AP was high in the epi- and bathypelagic zone of the eastern basin indicating a rapid regeneration of inorganic P for both prokaryotes and phytoplankton needs. Low activity and abundance characterized the Atlantic station, while opposite trends of these parameters were observed along the Mediterranean transect, showing the uncoupling between abundance and activity data. In the east Mediterranean Sea, decomposition processes increased probably in response to mesoscale structures which lead to organic matter downwelling.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Shingledecker, Christopher N.; Le Gal, Romane; Hincelin, Ugo
2016-10-20
The chemistry of dense interstellar regions was analyzed using a time-dependent gas–grain astrochemical simulation and a new chemical network that incorporates deuterated chemistry, taking into account nuclear spin states for the hydrogen chemistry and its deuterated isotopologues. With this new network, the utility of the [HCO{sup +}]/[DCO{sup +}] abundance ratio as a probe of the cosmic-ray ionization rate has been re-examined, with special attention paid to the effect of the initial value of the ortho-to-para ratio (OPR) of molecular hydrogen. After discussing the use of the probe for cold cores, we compare our results with previous theoretical and observational resultsmore » for a molecular cloud close to the supernova remnant W51C, which is thought to have an enhanced cosmic-ray ionization rate ζ caused by the nearby γ -ray source. In addition, we attempt to use our approach to estimate the cosmic-ray ionization rate for L1174, a dense core with an embedded star. Beyond the previously known sensitivity of [HCO{sup +}]/[DCO{sup +}] to ζ , we demonstrate its additional dependence on the initial OPR and, secondarily, on the age of the source, its temperature, and its density. We conclude that the usefulness of the [HCO{sup +}]/[DCO{sup +}] abundance ratio in constraining the cosmic-ray ionization rate in dense regions increases with the age of the source and the ionization rate as the ratio becomes far less sensitive to the initial value of the OPR.« less
NASA Astrophysics Data System (ADS)
Stone, Myra; Veilleux, Sylvain; González-Alfonso, Eduardo; Spoon, Henrik; Sturm, Eckhard
2018-02-01
We analyze Spitzer/InfraRed Spectrograph (IRS) observations of the OH 35 μm feature in 15 nearby (z ≲ 0.06) (ultra-)luminous infrared galaxies (U/LIRGs). All objects exhibit OH 35 μm purely in absorption, as expected. The small optical depth of this transition makes the strength of this feature a good indicator of the true OH column density. The measured OH 35 μm equivalent widths imply an average OH column density and a 1-σ standard deviation to the mean of {N}{OH}=1.31+/- 0.22× {10}17 cm‑2. This number is then compared with the hydrogen column density for a typical optical depth at 35 μm of ∼0.5 and gas-to-dust ratio of 125 to derive an OH-to-H abundance ratio of {X}{OH}=1.01+/- 0.15× {10}-6. This abundance ratio is formally a lower limit. It is consistent with the values generally assumed in the literature. The OH 35 μm line profiles predicted from published radiative transfer models constrained by observations of OH 65, 79, 84, and 119 μm in 5 objects (Mrk 231, Mrk 273, IRAS F05189-2524, IRAS F08572+3915, and IRAS F20551-4250) are also found to be consistent with the IRS OH 35 μm spectra.
Absolute quantification of microbial taxon abundances.
Props, Ruben; Kerckhof, Frederiek-Maarten; Rubbens, Peter; De Vrieze, Jo; Hernandez Sanabria, Emma; Waegeman, Willem; Monsieurs, Pieter; Hammes, Frederik; Boon, Nico
2017-02-01
High-throughput amplicon sequencing has become a well-established approach for microbial community profiling. Correlating shifts in the relative abundances of bacterial taxa with environmental gradients is the goal of many microbiome surveys. As the abundances generated by this technology are semi-quantitative by definition, the observed dynamics may not accurately reflect those of the actual taxon densities. We combined the sequencing approach (16S rRNA gene) with robust single-cell enumeration technologies (flow cytometry) to quantify the absolute taxon abundances. A detailed longitudinal analysis of the absolute abundances resulted in distinct abundance profiles that were less ambiguous and expressed in units that can be directly compared across studies. We further provide evidence that the enrichment of taxa (increase in relative abundance) does not necessarily relate to the outgrowth of taxa (increase in absolute abundance). Our results highlight that both relative and absolute abundances should be considered for a comprehensive biological interpretation of microbiome surveys.
Murrell, Ebony G.; Damal, Kavitha; Lounibos, L. P.; Juliano, Steven A.
2012-01-01
Coexistence of competitors may result if resources are sufficiently abundant to render competition unimportant, or if species differ in resource requirements. Detritus type has been shown to affect interspecific competitive outcomes between Aedes albopictus (Skuse) and Aedes aegypti (L.) larvae under controlled conditions. We assessed the relationships among spatial distributions of detritus types, nutrients, and aquatic larvae of these species in nature. We collected mosquitoes, water, and detritus from artificial containers across 24 Florida cemeteries that varied in relative abundances of Ae. aegypti and Ae. albopictus.We measured nutrient content of fine particulate organic matter in water samples as total N, P, and C and ratios of these nutrients. We quantified food availability via a bioassay, raising individual Aedes larvae in the laboratory in standard volumes of field-collected, particulate-containing water from each cemetery. Quantities of detritus types collected in standard containers were significant predictors of nutrients and nutrient ratios. Nutrient abundances were significant predictors of relative abundance of Ae. aegypti, and of larval survival and development by both species in the bioassay. Survival and development of larvae reared in particulate-containing water from sites decreased with decreasing relative abundance of Ae. aegypti. These data suggest that N, P, and C availabilities are determined by detritus inputs to containers and that these nutrients in turn determine the feeding environment encountered by larvae, the intensity of interspecific competition among larvae, and subsequent relative abundances of species at sites. Detritus inputs, nutrients, and food availability thus seem to contribute to distributions of Ae. aegypti and Ae. albopictus in cemetery containers throughout Florida. PMID:22707761
The Abundance of Iron-Peak Elements and the Dust Composition in eta Carinae: Manganese
NASA Technical Reports Server (NTRS)
Bautista, M. A.; Melendez, M.; Hartman, H.; Gull, T. R.; Lodders, K.
2010-01-01
We study the chemical abundances of the Strontium Filament found in the ejecta of (eta) Carinae. In particular, we derive the abundances of iron-peak elements front spectra of their singly ionized ions present in the optical/IR spectra. In this paper we analyze the spectrum of Mn II using a new non-LTE model for this system. In constructing this models we carried out theoretical calculations of radiative transition rates and electron impact excitation rate coefficients. We find that relative to Ni the gas phase abundance ratio of Mn is roughly solar, similar to the Cr abundance but in contrast to the large enhancements in the abundances of Sc and Ti. NVe interpret this result as an indication of non-equilibrium condensation in the ejecta of (eta) Carinae.
The relation of sediment texture to macro- and microplastic abundance in intertidal zone
NASA Astrophysics Data System (ADS)
Wahyuningsih, H.; Bangun, A. P.; Muhtadi, A.
2018-02-01
The intertidal zone is a waters area directly affected by the contamination of plastic debris from land and sea. The aim of this research were to analyze the relation of sediment texture to macro- and micro plastic abundance and also to determine appropriate management strategy. This research was conducted in intertidal zone Jaring Halus Village Langkat Regency North Sumatera Province on February-April 2017. Plastic debris was collected using quadrat transect. Sediment was collected with correct, up to a depth of least 30 cm. Abundance of micro plastic in Station 1 were positively tolerated with clay (0.509), and silt (0.787) and negatively correlations with sand (0.709) Station 2 were positively correlations with sand (0.645) and negatively correlations with clay (0.575), and silt (0.626) Station 3 were positively correlations with clay (0.435), and silt (0.466) and negatively correlations with sand (0.599). The abundance of microplastic was positively correlations with the abundance of microplastic (0.765). Microplastic density is directly proportional to the content of clay and dust. The higher the clay and dust content the higher the micro plastic density.
Improved Yttrium and Zirconium Abundances in Metal-Poor Stars
NASA Astrophysics Data System (ADS)
Violante, Renata; Biemont, E.; Cowan, J. J.; Sneden, C.
2012-01-01
Abstract We present new abundances of the lighter n-capture elements, Yttrium (Z=39) and Zirconium (Z=40) in the very metal poor, r-process rich stars BD+17 3248 and HD 221170. Very accurate abundances were obtained by use of the new transition probabilities for Y II published by Biémont et al. 2011, and Zr II by Malcheva et al. 2006, and by expanding the number of transitions employed for each element. For example, in BD+17 3248, we find log ɛπσιλον=-0.03 +/- 0.03 (σιγμα=0.15, from 23 lines) for Y II. As for Zr II, log ɛπσιλον = 0.65 +/- 0.03 (σɛγμα = 0.1, from 13 lines). The resulting abundance ratio is log ɛπσιλον [Y/Zr] = -0.68 +/- 0.05. The results for HD 221170 are in accord with those of BD+17 3248. The quantity of lines used to form the abundance means has increased significantly since the original studies of these stars, resulting in more trustworthy abundances. These observed abundance ratios are in agreement with an r-process-only value predicted from stellar models, but is under-abundant compared to an empirical model derived from direct analyses of meteoritic material. This ambiguity should stimulate further nucleosynthetic analysis to explain this abundance ratio. We would like to extend our gratitude to NSF grant AST-0908978 and the University of Texas Astronomy Department Rex G. Baker, Jr. Endowment for their financial support in this project.
APOGEE Chemical Abundances of the Sagittarius Dwarf Galaxy
NASA Astrophysics Data System (ADS)
Hasselquist, Sten; Shetrone, Matthew; Smith, Verne; Holtzman, Jon; McWilliam, Andrew; Fernández-Trincado, J. G.; Beers, Timothy C.; Majewski, Steven R.; Nidever, David L.; Tang, Baitian; Tissera, Patricia B.; Fernández Alvar, Emma; Allende Prieto, Carlos; Almeida, Andres; Anguiano, Borja; Battaglia, Giuseppina; Carigi, Leticia; Delgado Inglada, Gloria; Frinchaboy, Peter; García-Hernández, D. A.; Geisler, Doug; Minniti, Dante; Placco, Vinicius M.; Schultheis, Mathias; Sobeck, Jennifer; Villanova, Sandro
2017-08-01
The Apache Point Observatory Galactic Evolution Experiment provides the opportunity of measuring elemental abundances for C, N, O, Na, Mg, Al, Si, P, K, Ca, V, Cr, Mn, Fe, Co, and Ni in vast numbers of stars. We analyze thechemical-abundance patterns of these elements for 158 red giant stars belonging to the Sagittarius dwarf galaxy (Sgr). This is the largest sample of Sgr stars with detailed chemical abundances, and it is the first time that C, N, P, K, V, Cr, Co, and Ni have been studied at high resolution in this galaxy. We find that the Sgr stars with [Fe/H] ≳ -0.8 are deficient in all elemental abundance ratios (expressed as [X/Fe]) relative to the Milky Way, suggesting that the Sgr stars observed today were formed from gas that was less enriched by Type II SNe than stars formed in the Milky Way. By examining the relative deficiencies of the hydrostatic (O, Na, Mg, and Al) and explosive (Si, P, K, and Mn) elements, our analysis supports the argument that previous generations of Sgr stars were formed with a top-light initial mass function, one lacking the most massive stars that would normally pollute the interstellar medium with the hydrostatic elements. We use a simple chemical-evolution model, flexCE, to further support our claim and conclude that recent stellar generations of Fornax and the Large Magellanic Cloud could also have formed according to a top-light initial mass function.
Cha, YoonKyung; Cho, Kyung Hwa; Lee, Hyuk; Kang, Taegu; Kim, Joon Ha
2017-11-01
Despite a growing awareness of the problems associated with cyanobacterial blooms in rivers, and particularly in regulated rivers, the drivers of bloom formation and abundance in rivers are not well understood. We developed a Bayesian hierarchical model to assess the relative importance of predictors of summer cyanobacteria abundance, and to test whether the relative importance of each predictor varies by site, using monitoring data from 16 sites in the four major rivers of South Korea. The results suggested that temperature and residence time, but not nutrient levels, are important predictors of summer cyanobacteria abundance in rivers. Although the two predictors were of similar significance across the sites, the residence time was marginally better in accounting for the variation in cyanobacteria abundance. The model with spatial hierarchy demonstrated that temperature played a consistently significant role at all sites, and showed no effect from site-specific factors. In contrast, the importance of residence time varied significantly from site to site. This variation was shown to depend on the trophic state, indicated by the chlorophyll-a and total phosphorus levels. Our results also suggested that the magnitude of weir inflow is a key factor determining the cyanobacteria abundance under baseline conditions. Copyright © 2017 Elsevier Ltd. All rights reserved.
Carlson, J K; Hale, L F; Morgan, A; Burgess, G
2012-04-01
In the north-west Atlantic Ocean, stock assessments conducted for some commercially harvested coastal sharks indicate declines from 64 to 80% with respect to virgin population levels. While the status of commercially important species is available, abundance trend information for other coastal shark species in the north-west Atlantic Ocean are unavailable. Using a generalized linear modelling (GLM) approach, a relative abundance index was derived from 1994 to 2009 using observer data collected in a commercial bottom longline fishery. Trends in abundance and average size were estimated for bull shark Carcharhinus leucas, spinner shark Carcharhinus brevipinna, tiger shark Galeocerdo cuvier and lemon shark Negaprion brevirostris. Increases in relative abundance for all shark species ranged from 14% for C. brevipinna, 12% for C. leucas, 6% for N. brevirostris and 3% for G. cuvier. There was no significant change in the size at capture over the time period considered for all species. While the status of shark populations should not be based exclusively on abundance trend information, but ultimately on stock assessment models, results from this study provide some cause for optimism on the status of these coastal shark species. Published 2012. This article is a U.S. Government work and is in the public domain in the USA.
4He abundances: Optical versus radio recombination line measurements
NASA Astrophysics Data System (ADS)
Balser, Dana S.; Rood, Robert T.; Bania, T. M.
2010-04-01
Accurate measurements of the 4He/H abundance ratio are important in constraining Big Bang nucleosynthesis, models of stellar and Galactic evolution, and H ii region physics. We discuss observations of radio recombination lines using the Green Bank Telescope toward a small sample of H ii regions and planetary nebulae. We report 4He/H abundance ratio differences as high as 15-20% between optical and ratio data that are difficult to reconcile. Using the H ii regions S206 and M17 we determine 4He production in the Galaxy to be dY/dZ = 1.71 ± 0.86.
Effect of Gynosaponin on Rumen In vitro Methanogenesis under Different Forage-Concentrate Ratios
Manatbay, Bakhetgul; Cheng, Yanfen; Mao, Shengyong; Zhu, Weiyun
2014-01-01
The study aimed to investigate the effects of gynosaponin on in vitro methanogenesis under different forage-concentrate ratios (F:C ratios). Experiment was conducted with two kinds of F:C ratios (F:C = 7:3 and F:C = 3:7) and gynosaponin addition (0 mg and 16 mg) in a 2×2 double factorial design. In the presence of gynosaponin, methane production and acetate concentration were significantly decreased, whereas concentration of propionate tended to be increased resulting in a significant reduction (p<0.05) of acetate:propionate ratio (A:P ratio), in high-forage substrate. Gynosaponin treatment increased (p<0.05) the butyrate concentration in both F:C ratios. Denaturing gradient gel electrophoresis (DGGE) analysis showed there was no apparent shift in the composition of total bacteria, protozoa and methanogens after treated by gynosaponin under both F:C ratios. The real-time polymerase chain reaction (PCR) analysis indicated that variable F:C ratios significantly affected the abundances of Fibrobacter succinogenes, Rumninococcus flavefaciens, total fungi and counts of protozoa (p<0.05), but did not affect the mcrA gene copies of methanogens and abundance of total bacteria. Counts of protozoa and abundance of F.succinogenes were decreased significantly (p<0.05), whereas mcrA gene copies of methanogens were decreased slightly (p<0.10) in high-forage substrate after treated by gynosaponin. However, gynosaponin treatment under high-concentrate level did not affect the methanogenesis, fermentation characteristics and tested microbes. Accordingly, overall results suggested that gynosaponin supplementation reduced the in vitro methanogenesis and improved rumen fermentation under high-forage condition by changing the abundances of related rumen microbes. PMID:25083102
Spectroscopic abundance analyses of the 3He stars HD 185330 and 3 Cen A
NASA Astrophysics Data System (ADS)
Sadakane, Kozo; Nishimura, Masayoshi
2018-04-01
Abundances of 21 elements in two 3He stars, HD 185330 and 3 Cen A, have been analysed relative to the well-studied sharp-lined B3 V star ι Her. Six elements (P, Ti, Mn, Fe, Ni, and Br) are over-abundant in these two peculiar stars, while six elements (C, O, Mg, Al, S, and Cl) are under-abundant. Absorption lines of the two rarely observed heavy elements Br II and Kr II are detected in both stars and these elements are both over-abundant. The centroid wavelengths of the Ca II infrared triplet lines in these stars are redshifted relative to those lines in ι Her and the presence of heavy isotopes of Ca (mass number 44-46) in these two stars is confirmed. In spite of these similarities, there are several remarkable differences in abundance pattern between these two stars. N is under-abundant in HD 185330, as in many Hg-Mn stars, while it is significantly over-abundant in 3 Cen A. P and Ga are both over-abundant in 3 Cen A, while only P is over-abundant and no trace of absorption line of Ga II can be found in HD 185330. Large over-abundances of Kr and Xe are found in both stars, while the abundance ratio Kr/Xe is significantly different between them (-1.4 dex in HD 185330 and +1.2 dex in 3 Cen A). Some physical explanations are needed to account for these qualitative differences.
Spectroscopic abundance analyses of the 3He stars HD 185330 and 3 Cen A
NASA Astrophysics Data System (ADS)
Sadakane, Kozo; Nishimura, Masayoshi
2018-06-01
Abundances of 21 elements in two 3He stars, HD 185330 and 3 Cen A, have been analysed relative to the well-studied sharp-lined B3 V star ι Her. Six elements (P, Ti, Mn, Fe, Ni, and Br) are over-abundant in these two peculiar stars, while six elements (C, O, Mg, Al, S, and Cl) are under-abundant. Absorption lines of the two rarely observed heavy elements Br II and Kr II are detected in both stars and these elements are both over-abundant. The centroid wavelengths of the Ca II infrared triplet lines in these stars are redshifted relative to those lines in ι Her and the presence of heavy isotopes of Ca (mass number 44-46) in these two stars is confirmed. In spite of these similarities, there are several remarkable differences in abundance pattern between these two stars. N is under-abundant in HD 185330, as in many Hg-Mn stars, while it is significantly over-abundant in 3 Cen A. P and Ga are both over-abundant in 3 Cen A, while only P is over-abundant and no trace of absorption line of Ga II can be found in HD 185330. Large over-abundances of Kr and Xe are found in both stars, while the abundance ratio Kr/Xe is significantly different between them (-1.4 dex in HD 185330 and +1.2 dex in 3 Cen A). Some physical explanations are needed to account for these qualitative differences.
The abundances of hydrogen, helium, oxygen, and iron accelerated in large solar particle events
NASA Technical Reports Server (NTRS)
Mazur, J. E.; Mason, G. M.; Klecker, B.; Mcguire, R. E.
1993-01-01
Energy spectra measured in 10 large flares with the University of Maryland/Max-Planck-Institut sensors on ISEE I and Goddard Space Flight Center sensors on IMP 8 allowed us to determine the average H, He, O, and Fe abundances as functions of energy in the range of about 0.3-80 MeV/nucleon. Model fits to the spectra of individual events using the predictions of a steady state stochastic acceleration model with rigidity-dependent diffusion provided a means of interpolating small portions of the energy spectra not measured with the instrumentation. Particles with larger mass-to-charge ratios were relatively less abundant at higher energies in the flare-averaged composition. The Fe/O enhancement at low SEP energies was less than the Fe/O ratios observed in He-3-rich flares. Unlike the SEP composition averaged above 5 MeV/nucleon, the average SEP abundances above 0.3 MeV/nucleon were similar to the average solar wind.
C/O Ratios of Stars with Transiting Hot Jupiter Exoplanets
NASA Astrophysics Data System (ADS)
Teske, Johanna K.; Cunha, Katia; Smith, Verne V.; Schuler, Simon C.; Griffith, Caitlin A.
2014-06-01
The relative abundances of carbon and oxygen have long been recognized as fundamental diagnostics of stellar chemical evolution. Now, the growing number of exoplanet observations enable estimation of these elements in exoplanetary atmospheres. In hot Jupiters, the C/O ratio affects the partitioning of carbon in the major observable molecules, making these elements diagnostic of temperature structure and composition. Here we present measurements of carbon and oxygen abundances in 16 stars that host transiting hot Jupiter exoplanets, and we compare our C/O ratios to those measured in larger samples of host stars, as well as those estimated for the corresponding exoplanet atmospheres. With standard stellar abundance analysis we derive stellar parameters as well as [C/H] and [O/H] from multiple abundance indicators, including synthesis fitting of the [O I] λ6300 line and non-LTE corrections for the O I triplet. Our results, in agreement with recent suggestions, indicate that previously measured exoplanet host star C/O ratios may have been overestimated. The mean transiting exoplanet host star C/O ratio from this sample is 0.54 (C/O⊙ = 0.54), versus previously measured C/Ohost star means of ~0.65-0.75. We also observe the increase in C/O with [Fe/H] expected for all stars based on Galactic chemical evolution; a linear fit to our results falls slightly below that of other exoplanet host star studies but has a similar slope. Though the C/O ratios of even the most-observed exoplanets are still uncertain, the more precise abundance analysis possible right now for their host stars can help constrain these planets' formation environments and current compositions. Based on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California
Nature's starships. I. Observed abundances and relative frequencies of amino acids in meteorites
DOE Office of Scientific and Technical Information (OSTI.GOV)
Cobb, Alyssa K.; Pudritz, Ralph E., E-mail: cobbak@mcmaster.ca, E-mail: pudritz@physics.mcmaster.ca
The class of meteorites called carbonaceous chondrites are examples of material from the solar system which have been relatively unchanged from the time of their initial formation. These meteorites have been classified according to the temperatures and physical conditions of their parent planetesimals. We collate available data on amino acid abundance in these meteorites and plot the concentrations of different amino acids for each meteorite within various meteorite subclasses. We plot average concentrations for various amino acids across meteorites separated by subclass and petrologic type. We see a predominance in the abundance and variety of amino acids in CM2 andmore » CR2 meteorites. The range in temperature corresponding to these subclasses indicates high degrees of aqueous alteration, suggesting aqueous synthesis of amino acids. Within the CM2 and CR2 subclasses, we identify trends in relative frequencies of amino acids to investigate how common amino acids are as a function of their chemical complexity. These two trends (total abundance and relative frequencies) can be used to constrain formation parameters of amino acids within planetesimals. Our organization of the data supports an onion shell model for the temperature structure of planetesimals. The least altered meteorites (type 3) and their amino acids originated near cooler surface regions. The most active amino acid synthesis likely took place at intermediate depths (type 2). The most altered materials (type 1) originated furthest toward parent body cores. This region is likely too hot to either favor amino acid synthesis or for amino acids to be retained after synthesis.« less
Coronal thermal structure and abundances of supermetal-rich solar-type stars
NASA Technical Reports Server (NTRS)
Brickhouse, Nancy S. (Principal Investigator); Mushotzky, Richard F. (Technical Monitor)
2005-01-01
This observation is for grating spectroscopy of Tau Boo, a late-type star with very high metallicity (about twice solar). Despite the extreme condition of high metallicity in the photosphere, the abundance ratios of the corona appear consistent with the general picture of a coronal abundance/activity relation. The target was obtained by XMM-Newton on 24 June 2003 for 71900 sec. The European PI Antonio Maggio is responsible for data reduction. Members of our team presented at the Cool Stars Workshop 13 held in Hamburg, Germany in July 2004 and conferred at that time on the publication of results. This project is complete except for the final publication.
Stronger warming effects on microbial abundances in colder regions
Chen, Ji; Luo, Yiqi; Xia, Jianyang; Jiang, Lifen; Zhou, Xuhui; Lu, Meng; Liang, Junyi; Shi, Zheng; Shelton, Shelby; Cao, Junji
2015-01-01
Soil microbes play critical roles in regulating terrestrial carbon (C) cycle and its feedback to climate change. However, it is still unclear how the soil microbial community and abundance respond to future climate change scenarios. In this meta-analysis, we synthesized the responses of microbial community and abundance to experimental warming from 64 published field studies. Our results showed that warming significantly increased soil microbial abundance by 7.6% on average. When grouped by vegetation or soil types, tundras and histosols had the strongest microbial responses to warming with increased microbial, fungal, and bacterial abundances by 15.0%, 9.5% and 37.0% in tundra, and 16.5%, 13.2% and 13.3% in histosols, respectively. We found significant negative relationships of the response ratios of microbial, fungal and bacterial abundances with the mean annual temperature, indicating that warming had stronger effects in colder than warmer regions. Moreover, the response ratios of microbial abundance to warming were positively correlated with those of soil respiration. Our findings therefore indicate that the large quantities of C stored in colder regions are likely to be more vulnerable to climate warming than the soil C stored in other warmer regions. PMID:26658882
DOE Office of Scientific and Technical Information (OSTI.GOV)
Berg, Danielle A.; Skillman, Evan D.; Marble, Andrew R., E-mail: berg@astro.umn.edu, E-mail: skillman@astro.umn.edu, E-mail: amarble@nso.edu
We present new MMT spectroscopic observations of four dwarf galaxies representative of a larger sample observed by the Sloan Digital Sky Survey and identified by Peeples et al. as low-mass, high oxygen abundance outliers from the mass-metallicity relation. Peeples showed that these four objects (with metallicity estimates of 8.5 {<=} 12 + log(O/H) {<=} 8.8) have oxygen abundance offsets of 0.4-0.6 dex from the M{sub B} luminosity-metallicity relation. Our new observations extend the wavelength coverage to include the [O II] {lambda}{lambda}3726, 3729 doublet, which adds leverage in oxygen abundance estimates and allows measurements of N/O ratios. All four spectra aremore » low excitation, with relatively high N/O ratios (N/O {approx}> 0.10), each of which tend to bias estimates based on strong emission lines toward high oxygen abundances. These spectra all fall in a regime where the 'standard' strong-line methods for metallicity determinations are not well calibrated either empirically or by photoionization modeling. By comparing our spectra directly to photoionization models, we estimate oxygen abundances in the range of 7.9 {<=} 12 + log (O/H) {<=} 8.4, consistent with the scatter of the mass-metallicity relation. We discuss the physical nature of these galaxies that leads to their unusual spectra (and previous classification as outliers), finding their low excitation, elevated N/O, and strong Balmer absorption are consistent with the properties expected from galaxies evolving past the 'Wolf-Rayet galaxy' phase. We compare our results to the 'main' sample of Peeples and conclude that they are outliers primarily due to enrichment of nitrogen relative to oxygen and not due to unusually high oxygen abundances for their masses or luminosities.« less
Assessing relative abundance and reproductive success of shrubsteppe raptors
Lehman, Robert N.; Carpenter, L.B.; Steenhof, Karen; Kochert, Michael N.
1998-01-01
From 1991-1994, we quantified relative abundance and reproductive success of the Ferruginous Hawk (Buteo regalis), Northern Harrier (Circus cyaneus), Burrowing Owl (Speotytoc unicularia), and Short-eared Owl (Asio flammeus) on the shrubsteppe plateaus (benchlands) in and near the Snake River Birds of Prey National Conservation Area in southwestern Idaho. To assess relative abundance, we searched randomly selected plots using four sampling methods: point counts, line transects, and quadrats of two sizes. On a persampling-effort basis, transects were slightly more effective than point counts and quadrats for locating raptor nests (3.4 pairs detected/100 h of effort vs. 2.2-3.1 pairs). Random sampling using quadrats failed to detect a Short-eared Owl population increase from 1993 to 1994. To evaluate nesting success, we tried to determine reproductive outcome for all nesting attempts located during random, historical, and incidental nest searches. We compared nesting success estimates based on all nesting attempts, on attempts found during incubation, and the Mayfield model. Most pairs used to evaluate success were pairs found incidentally. Visits to historical nesting areas yielded the highest number of pairs per sampling effort (14.6/100 h), but reoccupancy rates for most species decreased through time. Estimates based on all attempts had the highest sample sizes but probably overestimated success for all species except the Ferruginous Hawk. Estimates of success based on nesting attempts found during incubation had the lowest sample sizes. All three methods yielded biased nesting snccess estimates for the Northern Harrier and Short-eared Owl. The estimate based on pairs found during incubation probably provided the least biased estimate for the Burrowing Owl. Assessments of nesting success were hindered by difficulties in confirming egg laying and nesting success for all species except the Ferruginous hawk.
NASA Astrophysics Data System (ADS)
Shakir, Muhammad Mussadiq; Ahmed, Sohail
2015-05-01
Soil arthropods are an important component of agroecosystems, contributing significantly to their biodiversity and functioning. However, seasonal patterns, population dynamics, and significant roles of these soil arthropods in improvement of soil structures and functions are influenced by many factors. The objective of the current study was to investigate soil arthropod abundance in relation to a blend of meteorological and edaphic factors and to find out the difference in abundance among various crops (sugarcane, cotton, wheat, alfalfa fodder, and citrus orchards). The arthropod sampling was done by pitfall traps and Tullgren extractions on fortnightly intervals. Soil temperature and relative humidity were noted on the field sites while analysis for soil pH, organic matter, and soil moisture contents were done in the laboratory. The rainfall data was obtained from an observatory. Results showed that significant differences were found in soil arthropod abundance across different sampling months and crops. Out of total 13,673 soil arthropods sampled, 38 % belonged to Collembola, followed by 15 % Hymenoptera, 15 % Acarina, 11 % Myriapods, 6 % Coleoptera, 5 % Orthoptera, and 5 % Araneae. Mean abundance per sample was highest in summer months as compared to winter. Overall abundance per sample was significantly different between all crops ( p < 0.05). Cluster analysis revealed four categories of soil arthropods according to abundance, i.e., highly abundant (Collembola, Acarina, Myripoda, Hymenoptera), moderately abundant (Orthoptera, Aranae, Coleoptera), least abundant (Dermaptera, Hemiptera, Diptera), and rare (Blattaria, Isoptera, Diplura, Lepidoptera). Soil temperature and soil organic matter showed significant positive correlation with abundance, while relative humidity was significantly negatively correlated. Soil moisture and soil pH showed no significant correlations while no correlation was found with total rainfall. PCA analysis revealed that soil surface
Sex ratio variation shapes the ecological effects of a globally introduced freshwater fish
Fryxell, David C.; Arnett, Heather A.; Apgar, Travis M.; Kinnison, Michael T.; Palkovacs, Eric P.
2015-01-01
Sex ratio and sexual dimorphism have long been of interest in population and evolutionary ecology, but consequences for communities and ecosystems remain untested. Sex ratio could influence ecological conditions whenever sexual dimorphism is associated with ecological dimorphism in species with strong ecological interactions. We tested for ecological implications of sex ratio variation in the sexually dimorphic western mosquitofish, Gambusia affinis. This species causes strong pelagic trophic cascades and exhibits substantial variation in adult sex ratios. We found that female-biased populations induced stronger pelagic trophic cascades compared with male-biased populations, causing larger changes to key community and ecosystem responses, including zooplankton abundance, phytoplankton abundance, productivity, pH and temperature. The magnitude of such effects indicates that sex ratio is important for mediating the ecological role of mosquitofish. Because both sex ratio variation and sexual dimorphism are common features of natural populations, our findings should encourage broader consideration of the ecological significance of sex ratio variation in nature, including the relative contributions of various sexually dimorphic traits to these effects. PMID:26490793
USDA-ARS?s Scientific Manuscript database
The ratios of regioisomers of 72 molecular species of triacylglycerols (TAG) in lesquerella oil were estimated using the electrospray ionization mass spectrometry of the lithium adducts of TAG in the HPLC fractions of lesquerella oil. The ratios of ion signal intensities (or relative abundances) of ...
Landbird species composition and relative abundance during migration along the Rio Grande
Wang Yong; Deborah M. Finch
1996-01-01
In this paper, we report species composition and relative abundances of stopover migrants during spring and fall migration along the middle Rio Grande in 1994. We recorded 157 landbird species using mist-netting and survey methods at two sites on the Rio Grande, the Bosque del Apache and the Rio Grande Nature Center. A total of 6,509 birds was captured during spring...
A Candidate Tidal Disruption Event in a Quasar at z = 2.359 from Abundance Ratio Variability
NASA Astrophysics Data System (ADS)
Liu, Xin; Dittmann, Alexander; Shen, Yue; Jiang, Linhua
2018-05-01
A small fraction of quasars show an unusually high nitrogen-to-carbon ratio (N/C) in their spectra. These “nitrogen-rich” (N-rich) quasars are a long-standing puzzle because their interstellar medium implies stellar populations with abnormally high metallicities. It has recently been proposed that N-rich quasars may result from tidal disruption events (TDEs) of stars by supermassive black holes. The rapid enhancement of nitrogen and the depletion of carbon due to the carbon–nitrogen–oxygen cycle in supersolar mass stars could naturally produce high N/C. However, the TDE hypothesis predicts that the N/C should change with time, which has never hitherto been observed. Here we report the discovery of the first N-rich quasar with rapid N/C variability that could be caused by a TDE. Two spectra separated by 1.7 years (rest-frame) show that the N III] λ1750/C III] λ1909 intensity ratio decayed by ∼86% ± 14% (1σ). Optical (rest-frame UV) light-curve and X-ray observations are qualitatively consistent with the TDE hypothesis; though, the time baseline falls short of a definitive proof. Putting the single-object discovery into context, statistical analyses of the ∼80 known N-rich quasars with high-quality archival spectra show evidence (at a 5σ significance level) of a decrease in N/C on timescales of >1 year (rest-frame) and a constant level of ionization (indicated by the C III] λ1909/C IV λ1549 intensity ratio). If confirmed, our results demonstrate the method of identifying TDE candidates in quasars via abundance ratio variability, opening a new window of TDE observations at high redshift (z > 2) with upcoming large-scale time-domain spectroscopic surveys.
Relating river geomorphology to the abundance of periphyton in New Zealand rivers
NASA Astrophysics Data System (ADS)
Hoyle, Jo; Hicks, Murray; Kilroy, Cathy
2013-04-01
Aquatic plants (including both periphyton and macrophytes) are a natural component of stream and river systems. However, abundant growth of instream plants can have detrimental impacts on the values of rivers. For example, periphyton in rivers provides basal resources for food webs and provides an important ecological service by removing dissolved nutrients and contaminants from the water column. However, high abundance of periphyton can have negative effects on habitat quality, water chemistry and biodiversity, and can reduce recreation and aesthetic values. The abundance of periphyton in rivers is influenced by a number of factors, but two key factors can be directly influenced by human activities: flow regimes and nutrient concentrations. Establishing quantitative relationships between periphyton abundance and these factors has proven to be difficult but remains an urgent priority due to the need to manage the ecological impacts of water abstraction and eutrophication of rivers worldwide. This need is particularly strong in New Zealand, where there is increasing demand for water for industry, power generation and agriculture. However, we currently have limited ability to predict the effects of changes in the mid-range flow regime on the presence/absence, abundance and composition of aquatic plants. Current water allocation limits are based on simple flow statistics, such as multiples of the median flow, but these are regional averages and can be quite unreliable on a site-specific basis. This stems largely from our limited ability to transform flow data into ecologically meaningful physical processes that directly affect plants (e.g., drag, abrasion, bed movement). The research we will present examines whether geomorphic variables, such as frequency of bed movement, are useful co-predictors in periphyton abundance-flow relationships. We collected topographic survey data and bed sediment data for 20 study reaches in the Manawatu-Wanganui region of New Zealand
APOGEE Chemical Abundances of the Sagittarius Dwarf Galaxy
DOE Office of Scientific and Technical Information (OSTI.GOV)
Hasselquist, Sten; Holtzman, Jon; Shetrone, Matthew
The Apache Point Observatory Galactic Evolution Experiment provides the opportunity of measuring elemental abundances for C, N, O, Na, Mg, Al, Si, P, K, Ca, V, Cr, Mn, Fe, Co, and Ni in vast numbers of stars. We analyze thechemical-abundance patterns of these elements for 158 red giant stars belonging to the Sagittarius dwarf galaxy (Sgr). This is the largest sample of Sgr stars with detailed chemical abundances, and it is the first time that C, N, P, K, V, Cr, Co, and Ni have been studied at high resolution in this galaxy. We find that the Sgr stars withmore » [Fe/H] ≳ −0.8 are deficient in all elemental abundance ratios (expressed as [X/Fe]) relative to the Milky Way, suggesting that the Sgr stars observed today were formed from gas that was less enriched by Type II SNe than stars formed in the Milky Way. By examining the relative deficiencies of the hydrostatic (O, Na, Mg, and Al) and explosive (Si, P, K, and Mn) elements, our analysis supports the argument that previous generations of Sgr stars were formed with a top-light initial mass function, one lacking the most massive stars that would normally pollute the interstellar medium with the hydrostatic elements. We use a simple chemical-evolution model, flexCE, to further support our claim and conclude that recent stellar generations of Fornax and the Large Magellanic Cloud could also have formed according to a top-light initial mass function.« less
Leaf Selection by Two Bornean Colobine Monkeys in Relation to Plant Chemistry and Abundance
Matsuda, Ikki; Tuuga, Augustine; Bernard, Henry; Sugau, John; Hanya, Goro
2013-01-01
Focusing on the chemical basis of dietary selection while investigating the nutritional ecology of animals helps understand their feeding biology. It is also important to consider food abundance/biomass while studying the mechanism of animal food selection. We studied leaf selection in two Bornean folivorous primates in relation to plant chemistry and abundance: proboscis monkeys inhabiting a secondary riverine forest and red leaf monkeys inhabiting a primary forest. Both species tended to prefer leaves containing higher protein levels, although more abundant plant species were chosen within the preferred species, probably to maximise energy gain per unit time. However, the two species showed clear differences in their detailed feeding strategy. Red leaf monkeys strictly chose to consume young leaves to adapt to the poor nutritional environment of the primary forest, whereas proboscis monkeys were not highly selective because of the better quality of its common food in the riverine forest. PMID:23695180
Weather-related indices of autumn–winter Dabbling Duck abundance in Middle North America
Michael L. Schummer; Richard Kaminski; Andrew H. Raedeke; David A. Graber
2010-01-01
Research on effects of key weather stimuli influencing waterfowl migration during autumn and winter is limited. We investigated relationships between changes in relative abundances of mallard (Anas platyrhynchos) and other dabbling ducks (Anas spp.) and weather variables at midlatitude locations in North America. We used waterfowl survey data from Missouri Conservation...
Lee, Sang-im; Lee, Hyunna; Jablonski, Piotr G.; Choe, Jae Chun
2017-01-01
Urban environments present novel and challenging habitats to wildlife. In addition to well-known difference in abiotic factors between rural and urban environments, the biotic environment, including microbial fauna, may also differ significantly. In this study, we aimed to compare the change in microbial abundance on eggshells during incubation between urban and rural populations of a passerine bird, the Eurasian Magpie (Pica pica), and examine the consequences of any differences in microbial abundances in terms of hatching success and nestling survival. Using real-time PCR, we quantified the abundances of total bacteria, Escherichia coli/Shigella spp., surfactin-producing Bacillus spp. and Candida albicans on the eggshells of magpies. We found that urban magpie eggs harboured greater abundances of E. coli/Shigella spp. and C. albicans before incubation than rural magpie eggs. During incubation, there was an increase in the total bacterial load, but a decrease in C. albicans on urban eggs relative to rural eggs. Rural eggs showed a greater increase in E. coli/Shigella spp. relative to their urban counterpart. Hatching success of the brood was generally lower in urban than rural population. Nestling survival was differentially related with the eggshell microbial abundance between urban and rural populations, which was speculated to be the result of the difference in the strength of the interaction among the microbes. This is the first demonstration that avian clutches in urban and rural populations differ in eggshell microbial abundance, which can be further related to the difference in hatching success and nestling survival in these two types of environments. We suggest that future studies on the eggshell microbes should investigate the interaction among the microbes, because the incubation and/or environmental factors such as urbanization or climate condition can influence the dynamic interactions among the microbes on the eggshells which can further determine the
Lee, Sang-Im; Lee, Hyunna; Jablonski, Piotr G; Choe, Jae Chun; Husby, Magne
2017-01-01
Urban environments present novel and challenging habitats to wildlife. In addition to well-known difference in abiotic factors between rural and urban environments, the biotic environment, including microbial fauna, may also differ significantly. In this study, we aimed to compare the change in microbial abundance on eggshells during incubation between urban and rural populations of a passerine bird, the Eurasian Magpie (Pica pica), and examine the consequences of any differences in microbial abundances in terms of hatching success and nestling survival. Using real-time PCR, we quantified the abundances of total bacteria, Escherichia coli/Shigella spp., surfactin-producing Bacillus spp. and Candida albicans on the eggshells of magpies. We found that urban magpie eggs harboured greater abundances of E. coli/Shigella spp. and C. albicans before incubation than rural magpie eggs. During incubation, there was an increase in the total bacterial load, but a decrease in C. albicans on urban eggs relative to rural eggs. Rural eggs showed a greater increase in E. coli/Shigella spp. relative to their urban counterpart. Hatching success of the brood was generally lower in urban than rural population. Nestling survival was differentially related with the eggshell microbial abundance between urban and rural populations, which was speculated to be the result of the difference in the strength of the interaction among the microbes. This is the first demonstration that avian clutches in urban and rural populations differ in eggshell microbial abundance, which can be further related to the difference in hatching success and nestling survival in these two types of environments. We suggest that future studies on the eggshell microbes should investigate the interaction among the microbes, because the incubation and/or environmental factors such as urbanization or climate condition can influence the dynamic interactions among the microbes on the eggshells which can further determine the
The abundance of boron in three halo stars
NASA Technical Reports Server (NTRS)
Duncan, Douglas K.; Lambert, David L.; Lemke, Michael
1992-01-01
B abundances for three halo stars: HD 140283, HD 19445, and HD 201891 are presented. Using recent determinations of the Be abundance in HD 140283, B/Be of 10 +5/-4 is found for this star, and similar ratios are inferred for HD 19445 and HD 201891. This ratio is equal to the minimum value of 10 expected from a synthesis of B and Be by high-energy cosmic-ray spallation reactions in the interstellar medium. It is shown that the accompanying synthesis of Li by alpha on alpha fusion reactions is probably a minor contributor to the observed 'primordial' Li of halo stars. The observed constant ratios of B/O and Be/O are expected if the principal channel of synthesis involves cosmic-ray CNO nuclei from the supernovae colliding with interstellar protons.
Galactic Abundance Patterns via Peimbert Types I & II Planetary Nebulae
NASA Astrophysics Data System (ADS)
Milingo, J. B.; Barnes, K. L.; Kwitter, K. B.; Souza, S. P.; Henry, R. B. C.; Skinner, J. N.
2005-12-01
Planetary Nebulae (PNe) are well known fonts of information about both stellar evolution and galactic chemical evolution. Abundance patterns in PNe are used to note signatures and constraints of nuclear processing, and as tracers of the distribution of metals throughout galaxies. In this poster abundance gradients and heavy element ratios are presented based upon newly acquired spectrophotometry of a sample of Galactic Peimbert Type I PNe. This new data set is extracted from spectra that extend from λ 3600 - 9600Å allowing the use of [S III] features at λ 9069 and 9532Å. Since a significant portion of S in PNe resides in S+2 and higher ionization stages, including these features improves the extrapolation from observed ion abundances to total element abundance. An alternate metallicity tracer, Sulfur is precluded from enhancement and depletion across the range of PNe progenitor masses. Its stability in intermediate mass stars makes it a useful tool to probe the natal conditions as well as the evolution of PNe progenitors. This is a continuation of our Type II PNe work, the impetus being to compile a relatively large set of line strengths and abundances with internally consistent observation, reduction, calibration, and abundance determination, minimizing systematic affects that come from compiling various data sets. This research is supported by the AAS Small Research Grants program, the Franklin & Marshall Committee on Grants, and NSF grant AST-0307118.
Re-examination of the relationship between marine virus and microbial cell abundances.
Wigington, Charles H; Sonderegger, Derek; Brussaard, Corina P D; Buchan, Alison; Finke, Jan F; Fuhrman, Jed A; Lennon, Jay T; Middelboe, Mathias; Suttle, Curtis A; Stock, Charles; Wilson, William H; Wommack, K Eric; Wilhelm, Steven W; Weitz, Joshua S
2016-01-25
Marine viruses are critical drivers of ocean biogeochemistry, and their abundances vary spatiotemporally in the global oceans, with upper estimates exceeding 10(8) per ml. Over many years, a consensus has emerged that virus abundances are typically tenfold higher than microbial cell abundances. However, the true explanatory power of a linear relationship and its robustness across diverse ocean environments is unclear. Here, we compile 5,671 microbial cell and virus abundance estimates from 25 distinct marine surveys and find substantial variation in the virus-to-microbial cell ratio, in which a 10:1 model has either limited or no explanatory power. Instead, virus abundances are better described as nonlinear, power-law functions of microbial cell abundances. The fitted scaling exponents are typically less than 1, implying that the virus-to-microbial cell ratio decreases with microbial cell density, rather than remaining fixed. The observed scaling also implies that viral effect sizes derived from 'representative' abundances require substantial refinement to be extrapolated to regional or global scales.
Lipchock, Sarah V.; Spielman, Andrew I.; Mennella, Julie A.; Mansfield, Corrine J.; Hwang, Liang-Dar; Douglas, Jennifer E.; Reed, Danielle R.
2018-01-01
We investigated whether the abundance of bitter receptor mRNA expression from human taste papillae is related to an individual’s perceptual ratings of bitter intensity and habitual intake of bitter drinks. Ratings of the bitterness of caffeine and quinine and three other bitter stimuli (urea, propylthiouracil, and denatonium benzoate) were compared with relative taste papilla mRNA abundance of bitter receptors that respond to the corresponding bitter stimuli in cell-based assays (TAS2R4, TAS2R10, TAS2R38, TAS2R43, and TAS2R46). We calculated caffeine and quinine intake from a food frequency questionnaire. The bitterness of caffeine was related to the abundance of the combined mRNA expression of these known receptors, r = 0.47, p = .05, and self-reported daily caffeine intake, t(18) = 2.78, p = .012. The results of linear modeling indicated that 47% of the variance among subjects in the rating of caffeine bitterness was accounted for by these two factors (habitual caffeine intake and taste receptor mRNA abundance). We observed no such relationships for quinine but consumption of its primary dietary form (tonic water) was uncommon. Overall, diet and TAS2R gene expression in taste papillae are related to individual differences in caffeine perception. PMID:28118781
Determination of lunar ilmenite abundances from remotely sensed data
NASA Technical Reports Server (NTRS)
Larson, Stephen M.; Johnson, Jeffrey R.; Singer, Robert B.
1991-01-01
The mineral ilmenite (FeTiO3) was found in abundance in lunar mare soils returned during the Apollo project. Lunar ilmenite often contains greater than 50 weight-percent titanium dioxide (TiO2), and is a primary potential resource for oxygen and other raw materials to supply future lunar bases. Chemical and spectroscopic analysis of the returned lunar soils produced an empirical function that relates the spectral reflectance ratio at 400 and 560 nm to the weight percent abundance of TiO2. This allowed mapping of the lunar TiO2 distribution using telescopic vidicon multispectral imaging from the ground; however, the time variant photometric response of the vidicon detectors produced abundance uncertainties of at least 2 to 5 percent. Since that time, solid-state charge-coupled device (CCD) detector technology capable of much improved photometric response has become available. An investigation of the lunar TiO2 distribution was carried out utilizing groundbased telescopic CCD multispectral imagery and spectroscopy. The work was approached in phases to develop optimum technique based upon initial results. The goal is to achieve the best possible TiO2 abundance maps from the ground as a precursor to lunar orbiter and robotic sample return missions, and to produce a better idea of the peak abundances of TiO2 for benefaction studies. These phases and the results are summarized.
Mesa, Laura A.; Howlett, Bradley G.; Grant, Jan E.; Didham, Raphael K.
2013-01-01
The potential movement of transgenes from genetically modified crops to non-genetically modified crops via insect-mediated pollen dispersal has been highlighted as one of the areas of greatest concern in regards to genetically modified crops. Pollen movement depends sensitively on spatial and temporal variation in the movement of insect pollinators between crop fields. This study tested the degree of variation in the diversity and relative abundance of flower-visiting insects entering versus leaving pak choi, Brassica rapa var. chinensis L. (Brassicales: Brassicaceae), crops throughout different stages of the flowering cycle. The relative abundance of flower-visiting insects varied significantly with Brassica crop phenology. Greater numbers of flower-visiting insects were captured inside rather than outside the crop fields, with the highest capture rates of flower-visitors coinciding with the peak of flowering in both spring-flowering and summer-flowering crops. Moreover, the ratio of flower-visiting insects entering versus leaving crop fields also varied considerably with changing crop phenology. Despite high variation in relative capture rates, the data strongly indicate non-random patterns of variation in insect movement in relation to crop phenology, with early-season aggregation of flower-visiting insects entering and remaining in the crop, and then mass emigration of flower-visiting insects leaving the crop late in the flowering season. Although pollen movement late in the flowering cycle might contribute relatively little to total seed set (and hence crop production), the findings here suggest that extensive late-season pollinator redistribution in the landscape could contribute disproportionately to long-distance gene movement between crops. PMID:23937538
Oxygen abundance in metal-poor dwarfs, derived from the forbidden line
NASA Astrophysics Data System (ADS)
Spite, M.; Spite, F.
1991-12-01
The oxygen abundance is redetermined in a few metal-poor dwarfs, using the oxygen forbidden line at 630 nm rather than the oxygen triplet at 777 nm previously used by Abia and Rebolo (1989). The ratios form O/Fe are clearly lower than the previous ones and are in agreement with the ratios found in the metal-poor red giants, suggesting that no real difference exists between dwarfs and giants. Finally, it can be argued that, pending the acquisition of additional information, the oxygen abundances derived from the forbidden line are more reliable than the abundances found from the triplet.
Stronger warming effects on microbial abundances in colder regions
Chen, Ji; Luo, Yiqi; Xia, Jianyang; ...
2015-12-10
Soil microbes play critical roles in regulating terrestrial carbon (C) cycle and its feedback to climate change. However, it is still unclear how the soil microbial community and abundance respond to future climate change scenarios. In this meta-analysis, we synthesized the responses of microbial community and abundance to experimental warming from 64 published field studies. Our results showed that warming significantly increased soil microbial abundance by 7.6% on average. When grouped by vegetation or soil types, tundras and histosols had the strongest microbial responses to warming with increased microbial, fungal, and bacterial abundances by 15.0%, 9.5% and 37.0% in tundra,more » and 16.5%, 13.2% and 13.3% in histosols, respectively. We found significant negative relationships of the response ratios of microbial, fungal and bacterial abundances with the mean annual temperature, indicating that warming had stronger effects in colder than warmer regions. Moreover, the response ratios of microbial abundance to warming were positively correlated with those of soil respiration. Our results therefore indicate that the large quantities of C stored in colder regions are likely to be more vulnerable to climate warming than the soil C stored in other warmer regions.« less
APOGEE Chemical Abundances of the Sagittarius Dwarf Galaxy System
NASA Astrophysics Data System (ADS)
Hasselquist, Sten; Shetrone, Matthew D.; Smith, Verne V.; Holtzman, Jon A.; McWilliam, Andrew; APOGEE Team
2018-06-01
The Apache Point Observatory Galactic Evolution Experiment provides the opportunity of measuring elemental abundances for C, N, O, Na, Mg, Al, Si, P, K, Ca, V, Cr, Mn, Fe, Co, and Ni in vast numbers of stars. We analyze the chemical-abundance patterns of these elements for 158 red giant stars belonging to the Sagittarius dwarf galaxy (Sgr). This is the largest sample of Sgr stars with detailed chemical abundances, and it is the first time that C, N, P, K, V, Cr, Co, and Ni have been studied at high resolution in this galaxy. We find that the Sgr stars with [Fe/H] > -0.8 are deficient in all elemental abundance ratios (expressed as [X/Fe]) relative to the Milky Way, suggesting that the Sgr stars observed today were formed from gas that was less enriched by Type II SNe than stars formed in the Milky Way. By examining the relative deficiencies of the hydrostatic (O, Na, Mg, and Al) and explosive (Si, P, K, and Mn) elements, our analysis supports the argument that previous generations of Sgr stars were formed with a top-light initial mass function, one lacking the most massive stars that would normally pollute the interstellar medium with the hydrostatic elements. We use a simple chemical-evolution model, flexCE, to further support our claim and conclude that recent stellar generations of Fornax and the Large Magellanic Cloud could also have formed according to a top-light initial mass function. We then exploit the unique chemical abundance patters of the Sgr core to trace stars belonging to the Sgr tidal streams elsewhere in the Milky Way.
Abundance Analysis of 17 Planetary Nebulae from High-Resolution Optical Spectroscopy
NASA Astrophysics Data System (ADS)
Sherrard, Cameroun G.; Sterling, Nicholas C.; Dinerstein, Harriet L.; Madonna, Simone; Mashburn, Amanda
2017-06-01
We present an abundance analysis of 17 planetary nebulae (PNe) observed with the 2D-coudé echelle spectrograph on the 2.7-m Harlan J. Smith telescope at McDonald Observatory. The spectra cover the wavelength range 3600--10,400 Å at a resolution R = 36,700, and are the first high-resolution optical spectra for many objects in our sample. The number of emission lines detected in individual nebulae range from ~125 to over 600. We derive temperatures, densities, and abundances from collisionally-excited lines using the PyNeb package (Luridiana et al. 2015, A&A, 573, A42) and the ionization correction factor scheme of Delgado-Inglada et al. (2014, MNRAS, 440, 536). The abundances of light elements agree with previous estimates for most of the PNe. Several objects exhibit emission lines of refractory elements such as K and Fe, and neutron-capture elements that can be enriched by the s-process. We find that K and Fe are depleted relative to solar by ~0.3--0.7~dex and 1-2 dex, respectively, and find evidence for s-process enrichments in 10 objects. Several objects in our sample exhibit C, N, and O recombination lines that are useful for abundance determinations. These transitions are used to compute abundance discrepancy factors (ADFs), the ratio of ionic abundances derived from permitted lines to those from collisionally-excited transitions. We explore relations among depletion factors, ADFs, s-process enrichment factors, and other nebular stellar and nebular properties. We acknowledge support from NSF awards AST-901432 and AST-0708429.
ISOTOPIC RATIOS OF {sup 18}O/{sup 17}O IN THE GALACTIC CENTRAL REGION
DOE Office of Scientific and Technical Information (OSTI.GOV)
Zhang, J. S.; Sun, L. L.; Riquelme, D.
The {sup 18}O/{sup 17}O isotopic ratio of oxygen is a crucial measure of the secular enrichment of the interstellar medium by ejecta from high-mass versus intermediate-mass stars. So far, however, there is a lack of data, particularly from the Galactic center (GC) region. Therefore, we have mapped typical molecular clouds in this region in the J = 1–0 lines of C{sup 18}O and C{sup 17}O with the Delingha 13.7 m telescope (DLH). Complementary pointed observations toward selected positions throughout the GC region were obtained with the IRAM 30 m and Mopra 22 m telescopes. C{sup 18}O/C{sup 17}O abundance ratios reflectingmore » the {sup 18}O/{sup 17}O isotope ratios were obtained from integrated intensity ratios of C{sup 18}O and C{sup 17}O. For the first time, C{sup 18}O/C{sup 17}O abundance ratios are determined for Sgr C (V ∼ −58 km s{sup −1}), Sgr D (V ∼ 80 km s{sup −1}), and the 1.°3 complex (V ∼ 80 km s{sup −1}). Through our mapping observations, abundance ratios are also obtained for Sgr A (∼0 and ∼50 km s{sup −1} component) and Sgr B2 (∼60 km s{sup −1}), which are consistent with the results from previous single-point observations. Our frequency-corrected abundance ratios of the GC clouds range from 2.58 ± 0.07 (Sgr D, V ∼ 80 km s{sup −1}, DLH) to 3.54 ± 0.12 (Sgr A, ∼50 km s{sup −1}). In addition, strong narrow components (line width less than 5 km s{sup −1}) from the foreground clouds are detected toward Sgr D (−18 km s{sup −1}), the 1.°3 complex (−18 km s{sup −1}), and M+5.3−0.3 (22 km s{sup −1}), with a larger abundance ratio around 4.0. Our results show a clear trend of lower C{sup 18}O/C{sup 17}O abundance ratios toward the GC region relative to molecular clouds in the Galactic disk. Furthermore, even inside the GC region, ratios appear not to be uniform. The low GC values are consistent with an inside-out formation scenario for our Galaxy.« less
Calcium ionization balance and argon/calcium abundance in solar flares
NASA Astrophysics Data System (ADS)
Antonucci, E.; Marocchi, D.; Gabriel, A. H.; Doschek, G. A.
1987-12-01
An earlier analysis of solar flare calcium spectra from XRP and P78-1 aimed at measuring the calcium ionization balance resulted in an ambiguity due to a line blend between the calcium q line and an Ar XVII line. In the present work the calcium line 'r' is included in the analysis in order to resolve this problem. It is shown that the correct calcium ionization balance is that indicated in the earlier paper as corresponding to an argon/calcium abundance ratio of 0.2. The argon/calcium abundance ratio in the group of solar flares studied is shown to be 0.2 + or - 0.2. It is further argued that while the abundance of heavy elements may be enhanced in energetic flare events, this enhancement is less for argon than for calcium, leading to an argon/calcium ratio smaller than that present in the quiet sun.
McCann, Robert S; Messina, Joseph P; MacFarlane, David W; Bayoh, M Nabie; Gimnig, John E; Giorgi, Emanuele; Walker, Edward D
2017-07-17
Spatial determinants of malaria risk within communities are associated with heterogeneity of exposure to vector mosquitoes. The abundance of adult malaria vectors inside people's houses, where most transmission takes place, should be associated with several factors: proximity of houses to larval habitats, structural characteristics of houses, indoor use of vector control tools containing insecticides, and human behavioural and environmental factors in and near houses. While most previous studies have assessed the association of larval habitat proximity in landscapes with relatively low densities of larval habitats, in this study these relationships were analysed in a region of rural, lowland western Kenya with high larval habitat density. 525 houses were sampled for indoor-resting mosquitoes across an 8 by 8 km study area using the pyrethrum spray catch method. A predictive model of larval habitat location in this landscape, previously verified, provided derivations of indices of larval habitat proximity to houses. Using geostatistical regression models, the association of larval habitat proximity, long-lasting insecticidal nets (LLIN) use, house structural characteristics (wall type, roof type), and peridomestic variables (cooking in the house, cattle near the house, number of people sleeping in the house) with mosquito abundance in houses was quantified. Vector abundance was low (mean, 1.1 adult Anopheles per house). Proximity of larval habitats was a strong predictor of Anopheles abundance. Houses without an LLIN had more female Anopheles gambiae s.s., Anopheles arabiensis and Anopheles funestus than houses where some people used an LLIN (rate ratios, 95% CI 0.87, 0.85-0.89; 0.84, 0.82-0.86; 0.38, 0.37-0.40) and houses where everyone used an LLIN (RR, 95% CI 0.49, 0.48-0.50; 0.39, 0.39-0.40; 0.60, 0.58-0.61). Cooking in the house also reduced Anopheles abundance across all species. The number of people sleeping in the house, presence of cattle near the house
NASA Astrophysics Data System (ADS)
Mott, A.; Steffen, M.; Caffau, E.; Spada, F.; Strassmeier, K. G.
2017-08-01
Context. Current three-dimensional (3D) hydrodynamical model atmospheres together with detailed spectrum synthesis, accounting for departures from local thermodynamic equilibrium (LTE), permit to derive reliable atomic and isotopic chemical abundances from high-resolution stellar spectra. Not much is known about the presence of the fragile 6Li isotope in evolved solar-metallicity red giant branch (RGB) stars, not to mention its production in magnetically active targets like HD 123351. Aims: A detailed spectroscopic investigation of the lithium resonance doublet in HD 123351 in terms of both abundance and isotopic ratio is presented. From fits of the observed spectrum, taken at the Canada-France-Hawaii telescope, with synthetic line profiles based on 1D and 3D model atmospheres, we seek to estimate the abundance of the 6Li isotope and to place constraints on its origin. Methods: We derive the lithium abundance A(Li) and the 6Li/7Li isotopic ratio by fitting different synthetic spectra to the Li-line region of a high-resolution CFHT spectrum (R = 120 000, S/N = 400). The synthetic spectra are computed with four different line lists, using in parallel 3D hydrodynamical CO5BOLD and 1D LHD model atmospheres and treating the line formation of the lithium components in non-LTE (NLTE). The fitting procedure is repeated with different assumptions and wavelength ranges to obtain a reasonable estimate of the involved uncertainties. Results: We find A(Li) = 1.69 ± 0.11 dex and 6Li/7Li = 8.0 ± 4.4% in 3D-NLTE, using the line list of Meléndez et al. (2012, A&A, 543, A29), updated with new atomic data for V I, which results in the best fit of the lithium line profile of HD 123351. Two other line lists lead to similar results but with inferior fit qualities. Conclusions: Our 2σ detection of the 6Li isotope is the result of a careful statistical analysis and the visual inspection of each achieved fit. Since the presence of a significant amount of 6Li in the atmosphere of a cool
The Cosmic Abundance of 3He: Green Bank Telescope Observations
NASA Astrophysics Data System (ADS)
Balser, Dana; Bania, Thomas
2018-01-01
The Big Bang theory for the origin of the Universe predicts that during the first ~1,000 seconds significant amounts of the light elements (2H, 3He, 4He, and 7Li) were produced. Many generations of stellar evolution in the Galaxy modifies these primordial abundances. Observations of the 3He+ hyperfine transition in Galactic HII regions reveals a 3He/H abundance ratio that is constant with Galactocentric radius to within the uncertainties, and is consistent with the primordial value as determined from cosmic microwave background experiments (e.g., WMAP). This "3He Plateau" indicates that the net production and destruction of 3He in stars is approximately zero. Recent stellar evolution models that include thermohaline mixing, however, predict that 3He/H abundance ratios should slightly decrease with Galactocentric radius, or in places in the Galaxy with lower star formation rates. Here we discuss sensitive Green Bank Telescope (GBT) observations of 3He+ at 3.46 cm in a subset of our HII region sample. We develop HII region models and derive accurate 3He/H abundance ratios to better constrain these new stellar evolution models.
Messages from the Reversing Layer: Clues to Planet Formation in Spectral Abundances
NASA Astrophysics Data System (ADS)
Brewer, John Michael; Fischer, Debra; Basu, Sarbani
2017-01-01
The abundances of elements in the protoplanetary disk evolve over time, but stellar abundances will reflect the initial chemical composition of the disk and this can provide constraints on the range of possible outcomes for planet interiors. Rocky planet habitability depends not just on the availability of liquid water, but also on volcansim and plate tectonics that can stabilize the climate on long timescales. The slow evolution of abundances in stellar photospheres, particularly abundance ratios between elements, makes them ideal laboratories to study primordial disk compositions.In my thesis work, I developed a new spectroscopic analysis procedure that derives gravities consistent with asteroseismology to within 0.05 dex as well as abundances for 15 elements. Using this procedure, we analyzed and published a catalog of accurate stellar parameters and precise abundances for more than 1600 stars and used those to investigate questions of planet formation. The C/O and Mg/Si ratios in the solar neighborhood could affect rocky planet habitability. For lucky cases where planet atmosphereic abundances can be measured, the stellar host C/O and [O/H] ratios carry information about the formation site and migration of hot Jupiters. I will present results on both rocky planet compositions and hot Jupiter migration and discuss how they can help us identify potentially habitable systems and discriminate between different planet formation models.
NASA Astrophysics Data System (ADS)
Hirschauer, Alec S.; Salzer, John J.; Janowiecki, Steven; Wegner, Gary A.
2018-02-01
We present updated metallicity relations for the spectral database of star-forming galaxies (SFGs) found in the KPNO International Spectroscopic Survey (KISS). New spectral observations of emission-line galaxies obtained from a variety of telescope facilities provide oxygen abundance information. A nearly fourfold increase in the number of KISS objects with robust metallicities relative to our previous analysis provides for an empirical abundance calibration to compute self-consistent metallicity estimates for all SFGs in the sample with adequate spectral data. In addition, a sophisticated spectral energy distribution fitting routine has provided robust calculations of stellar mass. With these new and/or improved galaxy characteristics, we have developed luminosity–metallicity (L–Z) relations, mass–metallicity (M *–Z) relations, and the so-called fundamental metallicity relation (FMR) for over 1450 galaxies from the KISS sample. This KISS M *–Z relation is presented for the first time and demonstrates markedly lower scatter than the KISS L–Z relation. We find that our relations agree reasonably well with previous publications, modulo modest offsets due to differences in the strong emission line metallicity calibrations used. We illustrate an important bias present in previous L–Z and M *–Z studies involving direct-method (T e ) abundances that may result in systematically lower slopes in these relations. Our KISS FMR shows consistency with those found in the literature, albeit with a larger scatter. This is likely a consequence of the KISS sample being biased toward galaxies with high levels of activity.
NASA Astrophysics Data System (ADS)
Aguado, Alfredo; Roncero, Octavio; Zanchet, Alexandre; Agúndez, Marcelino; Cernicharo, José
2017-03-01
The impact of the photodissociation of HCN and HNC isomers is analyzed in different astrophysical environments. For this purpose, the individual photodissociation cross sections of HCN and HNC isomers have been calculated in the 7-13.6 eV photon energy range for a temperature of 10 K. These calculations are based on the ab initio calculation of three-dimensional adiabatic potential energy surfaces of the 21 lower electronic states. The cross sections are then obtained using a quantum wave packet calculation of the rotational transitions needed to simulate a rotational temperature of 10 K. The cross section calculated for HCN shows significant differences with respect to the experimental one, and this is attributed to the need to consider non-adiabatic transitions. Ratios between the photodissociation rates of HCN and HNC under different ultraviolet radiation fields have been computed by renormalizing the rates to the experimental value. It is found that HNC is photodissociated faster than HCN by a factor of 2.2 for the local interstellar radiation field and 9.2 for the solar radiation field, at 1 au. We conclude that to properly describe the HNC/HCN abundance ratio in astronomical environments illuminated by an intense ultraviolet radiation field, it is necessary to use different photodissociation rates for each of the two isomers, which are obtained by integrating the product of the photodissociation cross sections and ultraviolet radiation field over the relevant wavelength range.
Fauteux, Lisa; Cottrell, Matthew T.; Kirchman, David L.; Borrego, Carles M.; Garcia-Chaves, Maria Carolina; del Giorgio, Paul A.
2015-01-01
There is now evidence that aerobic anoxygenic phototrophic (AAP) bacteria are widespread across aquatic systems, yet the factors that determine their abundance and activity are still not well understood, particularly in freshwaters. Here we describe the patterns in AAP abundance, cell size and pigment content across wide environmental gradients in 43 temperate and boreal lakes of Québec. AAP bacterial abundance varied from 1.51 to 5.49 x 105 cells mL-1, representing <1 to 37% of total bacterial abundance. AAP bacteria were present year-round, including the ice-cover period, but their abundance relative to total bacterial abundance was significantly lower in winter than in summer (2.6% and 7.7%, respectively). AAP bacterial cells were on average two-fold larger than the average bacterial cell size, thus AAP cells made a greater relative contribution to biomass than to abundance. Bacteriochlorophyll a (BChla) concentration varied widely across lakes, and was not related to AAP bacterial abundance, suggesting a large intrinsic variability in the cellular pigment content. Absolute and relative AAP bacterial abundance increased with dissolved organic carbon (DOC), whereas cell-specific BChla content was negatively related to chlorophyll a (Chla). As a result, both the contribution of AAP bacteria to total prokaryotic abundance, and the cell-specific BChla pigment content were positively correlated with the DOC:Chla ratio, both peaking in highly colored, low-chlorophyll lakes. Our results suggest that photoheterotrophy might represent a significant ecological advantage in highly colored, low-chlorophyll lakes, where DOC pool is chemically and structurally more complex. PMID:25927833
Fauteux, Lisa; Cottrell, Matthew T; Kirchman, David L; Borrego, Carles M; Garcia-Chaves, Maria Carolina; Del Giorgio, Paul A
2015-01-01
There is now evidence that aerobic anoxygenic phototrophic (AAP) bacteria are widespread across aquatic systems, yet the factors that determine their abundance and activity are still not well understood, particularly in freshwaters. Here we describe the patterns in AAP abundance, cell size and pigment content across wide environmental gradients in 43 temperate and boreal lakes of Québec. AAP bacterial abundance varied from 1.51 to 5.49 x 105 cells mL-1, representing <1 to 37% of total bacterial abundance. AAP bacteria were present year-round, including the ice-cover period, but their abundance relative to total bacterial abundance was significantly lower in winter than in summer (2.6% and 7.7%, respectively). AAP bacterial cells were on average two-fold larger than the average bacterial cell size, thus AAP cells made a greater relative contribution to biomass than to abundance. Bacteriochlorophyll a (BChla) concentration varied widely across lakes, and was not related to AAP bacterial abundance, suggesting a large intrinsic variability in the cellular pigment content. Absolute and relative AAP bacterial abundance increased with dissolved organic carbon (DOC), whereas cell-specific BChla content was negatively related to chlorophyll a (Chla). As a result, both the contribution of AAP bacteria to total prokaryotic abundance, and the cell-specific BChla pigment content were positively correlated with the DOC:Chla ratio, both peaking in highly colored, low-chlorophyll lakes. Our results suggest that photoheterotrophy might represent a significant ecological advantage in highly colored, low-chlorophyll lakes, where DOC pool is chemically and structurally more complex.
Linking phytoplankton community composition to seasonal changes in f-ratio
Ward, Bess B; Rees, Andrew P; Somerfield, Paul J; Joint, Ian
2011-01-01
Seasonal changes in nitrogen assimilation have been studied in the western English Channel by sampling at approximately weekly intervals for 12 months. Nitrate concentrations showed strong seasonal variations. Available nitrogen in the winter was dominated by nitrate but this was close to limit of detection from May to September, after the spring phytoplankton bloom. The 15N uptake experiments showed that nitrate was the nitrogen source for the spring phytoplankton bloom but regenerated nitrogen supported phytoplankton productivity throughout the summer. The average annual f-ratio was 0.35, which demonstrated the importance of ammonia regeneration in this dynamic temperate region. Nitrogen uptake rate measurements were related to the phytoplankton responsible by assessing the relative abundance of nitrate reductase (NR) genes and the expression of NR among eukaryotic phytoplankton. Strong signals were detected from NR sequences that are not associated with known phylotypes or cultures. NR sequences from the diatom Phaeodactylum tricornutum were highly represented in gene abundance and expression, and were significantly correlated with f-ratio. The results demonstrate that analysis of functional genes provides additional information, and may be able to give better indications of which phytoplankton species are responsible for the observed seasonal changes in f-ratio than microscopic phytoplankton identification. PMID:21544101
Reese, Katlynd M; Philpott, Stacy M
2012-10-01
Phoridae (Diptera) have widespread impacts on insect communities by limiting host ant behavior. However, phorid-ant interactions may vary with habitat or environmental conditions. Three Pseudacteon species parasitize Azteca instabilis Fr. Smith, a common ant in coffee agroecosystems, and limit A. instabilis foraging, indirectly benefiting other insects. However, little is known about how phorid abundance, behavior, and effects change with environmental conditions. In shaded coffee systems, coffee (Coffea arabica L.) grows under a range of shade conditions and management changes affect species interactions. For example, Pseudacteon spp. more strongly limit A. instabilis foraging in low-shade coffee habitats. We sampled relative abundance of three phorid species around A. instabilis nests in three coffee habitats varying in shade management during dry and wet seasons. We measured canopy cover, tree richness, tree density, leaf litter depth, and number of nearby trees with A. instabilis to determine whether these habitat factors correlate with phorid abundance. P. laciniosus Brown was the most abundant phorid in both seasons. Phorid relative abundance did not differ by habitat, but did differ by season. P. laciniosus accounted for a higher proportion of phorids in the wet season (91.4%) than in the dry season (78.9%), and P. planidorsalis Brown accounted for a larger percent in the dry season (21.1%) than in the wet season (7.3%). Phorid composition did not differ with habitat type, and none of the measured environmental variables correlated with changes in phorid composition. Thus, phorids in coffee agroecosystems respond to large seasonal differences, but not differences between coffee habitats.
A Metastable Equilibrium Model for the Relative Abundances of Microbial Phyla in a Hot Spring
Dick, Jeffrey M.; Shock, Everett L.
2013-01-01
Many studies link the compositions of microbial communities to their environments, but the energetics of organism-specific biomass synthesis as a function of geochemical variables have rarely been assessed. We describe a thermodynamic model that integrates geochemical and metagenomic data for biofilms sampled at five sites along a thermal and chemical gradient in the outflow channel of the hot spring known as “Bison Pool” in Yellowstone National Park. The relative abundances of major phyla in individual communities sampled along the outflow channel are modeled by computing metastable equilibrium among model proteins with amino acid compositions derived from metagenomic sequences. Geochemical conditions are represented by temperature and activities of basis species, including pH and oxidation-reduction potential quantified as the activity of dissolved hydrogen. By adjusting the activity of hydrogen, the model can be tuned to closely approximate the relative abundances of the phyla observed in the community profiles generated from BLAST assignments. The findings reveal an inverse relationship between the energy demand to form the proteins at equal thermodynamic activities and the abundance of phyla in the community. The distance from metastable equilibrium of the communities, assessed using an equation derived from energetic considerations that is also consistent with the information-theoretic entropy change, decreases along the outflow channel. Specific divergences from metastable equilibrium, such as an underprediction of the relative abundances of phototrophic organisms at lower temperatures, can be explained by considering additional sources of energy and/or differences in growth efficiency. Although the metabolisms used by many members of these communities are driven by chemical disequilibria, the results support the possibility that higher-level patterns of chemotrophic microbial ecosystems are shaped by metastable equilibrium states that depend on both the
Mack, Keenan M L; Bever, James D
2014-09-01
1. Negative plant-soil feedback occurs when the presence of an individual of a particular species at a particular site decreases the relative success of individuals of the same species compared to those other species at that site. This effect favors heterospecifics thereby facilitating coexistence and maintaining diversity. Empirical work has demonstrated that the average strengths of these feedbacks correlate with the relative abundance of species within a community, suggesting that feedbacks are an important driver of plant community composition. Understanding what factors contribute to the generation of this relationship is necessary for diagnosing the dynamic forces that maintain diversity in plant communities. 2. We used a spatially explicit, individual-based computer simulation to test the effects of dispersal distance, the size of feedback neighbourhoods, the strength of pairwise feedbacks and community wide variation of feedbacks, community richness, as well as life-history differences on the dependence of relative abundance on strength of feedback. 3. We found a positive dependence of relative abundance of a species on its average feedback for local scale dispersal and feedback. However, we found that the strength of this dependence decreased as either the spatial scale of dispersal and/or the spatial scale of feedback increased. We also found that for spatially local (i.e. relatively small) scale interaction and dispersal, as the mean strength of feedbacks in the community becomes less negative, the greater the increase in abundance produced by a comparable increase in species-specific average feedback. We found that life-history differences such as mortality rate did not generate a pattern with abundance, nor did they affect the relationship between abundance and average feedback. 4. Synthesis . Our results support the claim that empirical observations of a positive correlation between relative abundance and strength of average feedback serves as
ABUNDANCES IN THE LOCAL REGION. I. G AND K GIANTS
DOE Office of Scientific and Technical Information (OSTI.GOV)
Luck, R. Earle, E-mail: rel2@case.edu
2015-09-15
Parameters and abundances for 1133 stars of spectral types F, G, and K of luminosity class III have been derived. In terms of stellar parameters, the primary point of interest is the disagreement between gravities derived with masses determined from isochrones, and gravities determined from an ionization balance. This is not a new result per se, but the size of this sample emphasizes the severity of the problem. A variety of arguments led to the selection of the ionization-balance gravity as the working value. The derived abundances indicate that the giants in the solar region have Sun-like total abundances andmore » abundance ratios. Stellar evolution indicators have also been investigated with the Li abundances and the [C/Fe] and C/O ratios, indicating that standard processing has been operating in these stars. The more salient result for stellar evolution is that the [C/Fe] data across the red-giant clump indicates the presence of mass-dependent mixing in accord with standard stellar evolution predictions.« less
Galactic interstellar abundance surveys with IUE and IRAS
DOE Office of Scientific and Technical Information (OSTI.GOV)
Van Steenberg, M.E.
1987-01-01
This thesis is a survey of interstellar densities, abundances, and cloud structure in the Galaxy, using two NASA satellites: the International Ultraviolet Explorer (IUE) and Infrared Astronomical Satellite (IRAS). From IUE high-resolution spectra, the author measured equivalent widths of 18 ultraviolet resonance transitions and derived column densities for Si/sup +/, Mn/sup +/, Fe/sup +/, S/sup +/, and Zn/sup +/ toward 261 early-type stars. From the IRAS all-sky survey he also measured the infrared cirrus flux. He examined the variations of the measured parameters with spectral type, E(B-V), galactic longitude and latitude, distance from the Sun, and mean density. The hydrogen-columnmore » densities, metal-column densities, and gas-to-dust ratio are in good agreement with Copernicus surveys. The derived interstellar abundances yield mean logarithmic depletions. These depletions correlate with mean density but not with the physical density derived from Copernicus H/sub 2/ rotational states. Abundance ratios indicate a larger Fe halo abundance compared to Si, Mn, S, or Zn, which may result from selective grain processing in shocks or from Type I supernovae.« less
NASA Astrophysics Data System (ADS)
Lutz, B. L.; Womack, M.; Wagner, R. M.
1993-04-01
The Ohio State University Image Dissector Scanner on the Perkins 1.8-m telescope at the Lowell Observatory was used to record spectra of the plasma tails of Comets P/Halley (1986 III) and P/Bradfield (1987 XXIX, also 1987s). The ionic species CO(+), N2(+), CH(+), and H2O(+) were identified in these spectra, and column densities for them were calculated from measured fluxes. The observed N2(+)/H2O(+) ratios are at least an order of magnitude lower and the observed CH(+)/H2O(+) ratios are a factor of 100 higher than theoretical results. The abundance ratio N2/CO was derived in the plasma tail of Bradfield from N2(+) and CO(+) data, and found to be an order of magnitude higher than a value measured in Halley. The relative ion abundances of CH(+), N2(+), CO(+), and H2O(+) in Halley are consistent with in situ measurements obtained from the Giotto spacecraft.
Solar Coronal and photospheric abundances from solar energetic particle measurements
NASA Technical Reports Server (NTRS)
Breneman, H.; Stone, E. C.
1985-01-01
Solar energetic particle (SEP) elemental abundance data from the cosmic ray subsystem (CRS) aboard the Voyager 1 and 2 spacecraft are used to derive unfractionated coronal and photospheric abundances for elements with 3 Z or = 30. It is found that the ionic charge-to-mass ratio (Q/M) is the principal organizing parameter for the fractionation of SEPs by acceleration and propagation processes and for flare-to-flare variability, making possible a single-parameter Q/M-dependent correction to the average SEP abundances to obtain unfractionated coronal abundances. A further correction based on first ionization potential allows the determination of unfractionated photospheric abundances.
Solar coronal and photospheric abundances from solar energetic particle measurements
NASA Technical Reports Server (NTRS)
Breneman, H. H.; Stone, E. C.
1985-01-01
Solar energetic particle (SEP) elemental abundance data from the cosmic ray subsystem (CRS) aboard the Voyager 1 and 2 spacecraft are used to derive unfractionated coronal and photospheric abundances for elements with Z = 6-30. It is found that the ionic charge-to-mass ratio (Q/M) is the principal organizing parameter for the fractionation of SEPs by acceleration and propagation processes and for flare-to-flare variability, making possible a single-parameter Q/M-dependent correction to the average SEP abundances to obtain unfractionated coronal abundances. A further correction based on first ionization potential allows the determination of unfractionated photospheric abundances.
Solar coronal and photospheric abundances from solar energetic particle measurements
NASA Technical Reports Server (NTRS)
Breneman, H.; Stone, E. C.
1985-01-01
Solar energetic particle (SEP) elemental abundance data from the Cosmic Ray Subsystem (CRS) aboard the Voyager 1 and 2 spacecraft are used to derive unfractionated coronal and photospheric abundances for elements with 3 = or Z or = 30. The ionic charge-to-mass ratio (Q/M) is the principal organizing parameter for the fractionation of SEPs by acceleration and propagation processes and for flare-to-flare variability, making possible a single-parameter Q/M-dependent correction to the average SEP abundances to obtain unfractionated coronal abundances. A further correction based on first ionization potential allows the determination of unfractionated photospheric abundances.
Size matters: abundance matching, galaxy sizes, and the Tully-Fisher relation in EAGLE
NASA Astrophysics Data System (ADS)
Ferrero, Ismael; Navarro, Julio F.; Abadi, Mario G.; Sales, Laura V.; Bower, Richard G.; Crain, Robert A.; Frenk, Carlos S.; Schaller, Matthieu; Schaye, Joop; Theuns, Tom
2017-02-01
The Tully-Fisher relation (TFR) links the stellar mass of a disc galaxy, Mstr, to its rotation speed: it is well approximated by a power law, shows little scatter, and evolves weakly with redshift. The relation has been interpreted as reflecting the mass-velocity scaling (M ∝ V3) of dark matter haloes, but this interpretation has been called into question by abundance-matching (AM) models, which predict the galaxy-halo mass relation to deviate substantially from a single power law and to evolve rapidly with redshift. We study the TFR of luminous spirals and its relation to AM using the EAGLE set of Λ cold dark matter (ΛCDM) cosmological simulations. Matching both relations requires disc sizes to satisfy constraints given by the concentration of haloes and their response to galaxy assembly. EAGLE galaxies approximately match these constraints and show a tight mass-velocity scaling that compares favourably with the observed TFR. The TFR is degenerate to changes in galaxy formation efficiency and the mass-size relation; simulations that fail to match the galaxy stellar mass function may fit the observed TFR if galaxies follow a different mass-size relation. The small scatter in the simulated TFR results because, at fixed halo mass, galaxy mass and rotation speed correlate strongly, scattering galaxies along the main relation. EAGLE galaxies evolve with lookback time following approximately the prescriptions of AM models and the observed mass-size relation of bright spirals, leading to a weak TFR evolution consistent with observation out to z = 1. ΛCDM models that match both the abundance and size of galaxies as a function of stellar mass have no difficulty reproducing the observed TFR and its evolution.
Climate-related variability in abundance of mesozooplankton in the northern Gulf of Alaska 1998-2009
NASA Astrophysics Data System (ADS)
Sousa, Leandra; Coyle, Kenneth O.; Barry, Ronald P.; Weingartner, Thomas J.; Hopcroft, Russell R.
2016-10-01
Significant changes in fisheries resources have occurred in the Gulf of Alaska (GOA) in the mid 1970s, with an increase in groundfish and a decrease in crab and shrimp populations. Increased fishing pressure and such events suggest that the GOA is susceptible to climate variation; however the mechanistic links between ecosystem change and climate remain unclear. At-sea surveys were undertaken during the month of May from 1998 to 2009 to collect data on zooplankton abundance and water mass properties in the northern GOA. Significant changes in temperature, salinity and zooplankton abundance were identified during this period. The euphausiid Thysanoessa inermis and the copepod Calanus marshallae had increased abundances in years when there was a strong phytoplankton spring bloom preceded by anomalously cold winters. The euphausiid Euphausia pacifica and the copepods Pseudocalanus spp., Neocalanus plumchrus/flemingeri, and Oithona spp. were more resilient to relatively high mean water temperatures. High zooplankton abundances in years of substantial cross-shelf mixing suggest that iron and nutrient transport between the shelf and oceanic domains are essential for sustaining high zooplankton populations via phytoplankton blooms. The abundance of zooplankton in the northern GOA is highly influenced by advective processes and changes in temperature. Further understanding of biological and physical mechanisms that control the GOA ecosystem are of major importance to predict the response of zooplankton communities to environmental changes.
Stien, A; Voutilainen, L; Haukisalmi, V; Fuglei, E; Mørk, T; Yoccoz, N G; Ims, R A; Henttonen, H
2010-01-01
The intestinal parasite community of Arctic foxes (Vulpes lagopus) on the Svalbard archipelago in the High Arctic was investigated in relation to the abundance and distribution of intermediate hosts. Five species of cestodes (Echinococcus multilocularis, Taenia crassiceps, Taenia polyacantha, Taenia krabbei and Diphyllobothrium sp.), ascaridoid nematodes and one unidentified acanthocephalan species were found. The cestodes E. multilocularis, T. crassiceps and T. polyacantha all showed a decreasing prevalence in the fox population with increasing distance from their spatially restricted intermediate host population of sibling voles (Microtus levis). In addition, the prevalence of E. multilocularis in a sample from the vole population was directly related to the local vole abundance. The cestode T. krabbei uses reindeer as intermediate host, and its prevalence in female foxes was positively related to the density of reindeer (Rangifer tarandus platyrhyncus). Finally, the prevalence of the ascaridoid nematodes also decreased with increasing distance from the vole population, a finding that is consistent with the idea that voles are involved in transmission, most likely as paratenic hosts. The prevalence of the remaining species (Diphyllobothrium sp. and an unidentified acanthocephalan) was very low. We conclude that the distribution and abundance of intermediate host structure the gastrointestinal parasite community of the Arctic fox on the Svalbard archipelago.
THE CONTENT AND RELATIVE BASE RATIOS OF RIBONUCLEIC ACID IN AMOEBA
Iverson, Ray M.
1964-01-01
The amount and relative base ratios of ribonucleic acid (RNA) in the nucleus and cytoplasm of Amoeba proteus and A. dubia, and of homospecies cells obtained by nuclear transfer with A. proteus, have been determined by microelectrophoresis. In A. proteus the average amounts of RNA in the nucleus and the cytoplasm were 134. micromicrograms and 2520. micromicrograms; in A. dubia the averages for the nucleus and cytoplasm were 67. micromicrograms and 1427. micromicrograms. The relative base ratio of RNA of the nucleus is similar to that of the RNA of the cytoplasm within a species, but the two species differed in this respect. Homospecies nuclear transfer did not affect the relative base ratio or amount of RNA. PMID:14105213
The Abundance of Helium in the Source Plasma of Solar Energetic Particles
NASA Astrophysics Data System (ADS)
Reames, Donald V.
2017-11-01
Studies of patterns of abundance enhancements of elements, relative to solar coronal abundances, in large solar energetic-particle (SEP) events, and of their power-law dependence on the mass-to-charge ratio, A/Q, of the ions, have been used to determine the effective source-plasma temperature, T, that defines the Q-values of the ions. We find that a single assumed value for the coronal reference He/O ratio in all SEP events is often inconsistent with the transport-induced power-law trend of the other elements. In fact, the coronal He/O varies rather widely from one SEP event to another. In the large Fe-rich SEP events with T ≈ 3 MK, where shock waves, driven out by coronal mass ejections (CMEs), have reaccelerated residual ions from impulsive suprathermal events that occur earlier in solar active regions, He/O ≈ 90, a ratio similar to that in the slow solar wind, which may also originate from active regions. Ions in the large SEP events with T < 2 MK may be accelerated outside active regions, and have values of 40 ≤ He/O ≤ 60. Mechanisms that determine coronal abundances, including variations of He/O, are likely to occur near the base of the corona (at ≈ 1.1 RS) and thus to affect both SEPs (at 2 - 3 RS) and the solar wind. Other than He, reference coronal abundances for heavier elements show little temperature dependence or systematic difference between SEP events; He, the element with the highest first-ionization potential, is unique. The CME-driven shock waves probe the same regions of space, at ≈ 2 RS near active regions, which are also likely sources of the slow solar wind, providing complementary information on conditions in those regions.
Kageyama, Shinya; Takeshita, Toru; Asakawa, Mikari; Shibata, Yukie; Takeuchi, Kenji; Yamanaka, Wataru; Yamashita, Yoshihisa
2017-01-01
Increasing attention is being focused on evaluating the salivary microbiota as a promising method for monitoring oral health; however, its bacterial composition greatly differs from that of dental plaque microbiota, which is a dominant etiologic factor of oral diseases. This study evaluated the relative abundance of subgingival plaque-specific bacteria in the salivary microbiota and examined a relationship between the abundance and severity of periodontal condition in patients with periodontitis. Four samples (subgingival and supragingival plaques, saliva, and tongue coating) per each subject were collected from 14 patients with a broad range of severity of periodontitis before periodontal therapy. The bacterial composition was analyzed by 16S rRNA gene amplicon sequencing using Ion PGM. Of the 66 species-level operational taxonomic units (OTUs) representing the mean relative abundance of ≥ 1% in any of the four niches, 12 OTUs corresponding to known periodontal pathogens, including Porphyromonas gingivalis, were characteristically predominant in the subgingival plaque and constituted 37.3 ± 22.9% of the microbiota. The total relative abundance of these OTUs occupied only 1.6 ± 1.2% of the salivary microbiota, but significantly correlated with the percentage of diseased sites (periodontal pocket depth ≥ 4 mm; r = 0.78, P < 0.001), in addition to the abundance of subgingival plaque microbiota (r = 0.61, P = 0.02). After periodontal therapy, the total relative abundance of these 12 OTUs was evaluated as well as before periodontal therapy and reductions of the abundance through periodontal therapy were strongly correlated in saliva and subgingival plaque (r = 0.81, P < 0.001). Based on these results, salivary microbiota might be a promising target for the evaluation of subgingival plaque-derived bacteria representing the present condition of periodontal health.
Kageyama, Shinya; Takeshita, Toru; Asakawa, Mikari; Shibata, Yukie; Takeuchi, Kenji; Yamanaka, Wataru
2017-01-01
Increasing attention is being focused on evaluating the salivary microbiota as a promising method for monitoring oral health; however, its bacterial composition greatly differs from that of dental plaque microbiota, which is a dominant etiologic factor of oral diseases. This study evaluated the relative abundance of subgingival plaque-specific bacteria in the salivary microbiota and examined a relationship between the abundance and severity of periodontal condition in patients with periodontitis. Four samples (subgingival and supragingival plaques, saliva, and tongue coating) per each subject were collected from 14 patients with a broad range of severity of periodontitis before periodontal therapy. The bacterial composition was analyzed by 16S rRNA gene amplicon sequencing using Ion PGM. Of the 66 species-level operational taxonomic units (OTUs) representing the mean relative abundance of ≥ 1% in any of the four niches, 12 OTUs corresponding to known periodontal pathogens, including Porphyromonas gingivalis, were characteristically predominant in the subgingival plaque and constituted 37.3 ± 22.9% of the microbiota. The total relative abundance of these OTUs occupied only 1.6 ± 1.2% of the salivary microbiota, but significantly correlated with the percentage of diseased sites (periodontal pocket depth ≥ 4 mm; r = 0.78, P < 0.001), in addition to the abundance of subgingival plaque microbiota (r = 0.61, P = 0.02). After periodontal therapy, the total relative abundance of these 12 OTUs was evaluated as well as before periodontal therapy and reductions of the abundance through periodontal therapy were strongly correlated in saliva and subgingival plaque (r = 0.81, P < 0.001). Based on these results, salivary microbiota might be a promising target for the evaluation of subgingival plaque-derived bacteria representing the present condition of periodontal health. PMID:28369125
NASA Astrophysics Data System (ADS)
Zaitsev, Vladimir Y.; Radostin, Andrey V.; Pasternak, Elena; Dyskin, Arcady
2017-09-01
Results of examination of experimental data on non-linear elasticity of rocks using experimentally determined pressure dependences of P- and S-wave velocities from various literature sources are presented. Overall, over 90 rock samples are considered. Interpretation of the data is performed using an effective-medium description in which cracks are considered as compliant defects with explicitly introduced shear and normal compliances without specifying a particular crack model with an a priori given ratio of the compliances. Comparison with the experimental data indicated abundance (˜ 80 %) of cracks with the normal-to-shear compliance ratios that significantly exceed the values typical of conventionally used crack models (such as penny-shaped cuts or thin ellipsoidal cracks). Correspondingly, rocks with such cracks demonstrate a strongly decreased Poisson ratio including a significant (˜ 45 %) portion of rocks exhibiting negative Poisson ratios at lower pressures, for which the concentration of not yet closed cracks is maximal. The obtained results indicate the necessity for further development of crack models to account for the revealed numerous examples of cracks with strong domination of normal compliance. Discovering such a significant number of naturally auxetic rocks is in contrast to the conventional viewpoint that occurrence of a negative Poisson ratio is an exotic fact that is mostly discussed for artificial structures.
The Mysterious Case of the Solar Argon Abundance Near Sunspots in Flares
NASA Astrophysics Data System (ADS)
Doschek, George A.; Warren, Harry
2016-05-01
Recently Doschek et al. (2015, ApJL, 808, L7) reported on an observation of an enhancement of the abundance of Ar XIV relative to Ca XIV of about a factor of 30 near a sunspot during a flare, observed in spectra recorded by the Extreme-ultraviolet Imaging Spectrometer (EIS) on the Hinode spacecraft. This enhancement yields an argon/calcium abundance ratio 7 times greater than expected from the photospheric abundances. Such a large abundance anomaly is unprecedented in the solar atmosphere. We interpreted this result as due to an inverse First Ionization Potential (FIP) effect. Argon is a high-FIP element and calcium is a low-FIP element. In the published work two lines of Ar XIV were observed and one line was tentatively identified as an Ar XI line. The number of argon lines was limited by the limitations of the flare study that was executed. In this paper we report observing a similar enhancement in a full-CCD EIS flare spectrum in argon lines with reasonable statistics and lack of blending that lie within the EIS wavelength ranges. The observed lines include two Ar XI lines, four Ar XIII lines, six Ar XIV lines, and one Ar XV line. The enhancement is far less than reported in Doschek et al. (2015) but exhibits similar morphology. The argon abundance is close to a photospheric abundance in the enhanced area, and is only marginally an inverse FIP effect. However, as for the published cases, this newly discovered enhancement occurs in association with a sunspot in a small area only a few arcsec in size and therefore we feel it is produced by the same physics that produced the strong inverse FIP case. There is no enhancement effect observed in the normally high-FIP sulfur and oxygen line ratios relative to lines of low-FIP elements available to EIS. Calculations of path lengths in the strongest enhanced area in Doschek et al. (2015) indicate that the argon/calcium enhancement is due to a depletion of low-FIP elements. This work is supported by a NASA Hinode grant.
Counihan, T.D.; Miller, Allen I.; Parsley, M.J.
1999-01-01
The development of recruitment monitoring programs for age-0 white sturgeons Acipenser transmontanus is complicated by the statistical properties of catch-per-unit-effort (CPUE) data. We found that age-0 CPUE distributions from bottom trawl surveys violated assumptions of statistical procedures based on normal probability theory. Further, no single data transformation uniformly satisfied these assumptions because CPUE distribution properties varied with the sample mean (??(CPUE)). Given these analytic problems, we propose that an additional index of age-0 white sturgeon relative abundance, the proportion of positive tows (Ep), be used to estimate sample sizes before conducting age-0 recruitment surveys and to evaluate statistical hypothesis tests comparing the relative abundance of age-0 white sturgeons among years. Monte Carlo simulations indicated that Ep was consistently more precise than ??(CPUE), and because Ep is binomially rather than normally distributed, surveys can be planned and analyzed without violating the assumptions of procedures based on normal probability theory. However, we show that Ep may underestimate changes in relative abundance at high levels and confound our ability to quantify responses to management actions if relative abundance is consistently high. If data suggest that most samples will contain age-0 white sturgeons, estimators of relative abundance other than Ep should be considered. Because Ep may also obscure correlations to climatic and hydrologic variables if high abundance levels are present in time series data, we recommend ??(CPUE) be used to describe relations to environmental variables. The use of both Ep and ??(CPUE) will facilitate the evaluation of hypothesis tests comparing relative abundance levels and correlations to variables affecting age-0 recruitment. Estimated sample sizes for surveys should therefore be based on detecting predetermined differences in Ep, but data necessary to calculate ??(CPUE) should also be
Predicting network modules of cell cycle regulators using relative protein abundance statistics.
Oguz, Cihan; Watson, Layne T; Baumann, William T; Tyson, John J
2017-02-28
Parameter estimation in systems biology is typically done by enforcing experimental observations through an objective function as the parameter space of a model is explored by numerical simulations. Past studies have shown that one usually finds a set of "feasible" parameter vectors that fit the available experimental data equally well, and that these alternative vectors can make different predictions under novel experimental conditions. In this study, we characterize the feasible region of a complex model of the budding yeast cell cycle under a large set of discrete experimental constraints in order to test whether the statistical features of relative protein abundance predictions are influenced by the topology of the cell cycle regulatory network. Using differential evolution, we generate an ensemble of feasible parameter vectors that reproduce the phenotypes (viable or inviable) of wild-type yeast cells and 110 mutant strains. We use this ensemble to predict the phenotypes of 129 mutant strains for which experimental data is not available. We identify 86 novel mutants that are predicted to be viable and then rank the cell cycle proteins in terms of their contributions to cumulative variability of relative protein abundance predictions. Proteins involved in "regulation of cell size" and "regulation of G1/S transition" contribute most to predictive variability, whereas proteins involved in "positive regulation of transcription involved in exit from mitosis," "mitotic spindle assembly checkpoint" and "negative regulation of cyclin-dependent protein kinase by cyclin degradation" contribute the least. These results suggest that the statistics of these predictions may be generating patterns specific to individual network modules (START, S/G2/M, and EXIT). To test this hypothesis, we develop random forest models for predicting the network modules of cell cycle regulators using relative abundance statistics as model inputs. Predictive performance is assessed by the
USDA-ARS?s Scientific Manuscript database
The ratios of regioisomers of 74 molecular species of triacylglycerols (TAG) in lesquerella oil were estimated using HPLC and the electrospray ionization mass spectrometry of the lithium adducts of TAG in the HPLC fractions of lequerella oil. The ratios of relative abundances of the fragment ions fr...
Site-selective nitrogen isotopic ratio measurement of nitrous oxide using 2 microm diode lasers.
Uehara, K; Yamamoto, K; Kikugawa, T; Yoshida, N
2003-03-15
We demonstrate a high-precision measurement of the isotopomer abundance ratio 14N(15)N(16)O/15N(14)N(16)O/14N(14)N(16)O (approximately 0.37/0.37/100) using three wavelength-modulated 2 microm diode lasers combined with a multipass cell which provides different optical pathlengths of 100 and 1 m to compensate the large abundance difference. A set of absorption lines for which the absorbances have almost the same temperature dependence are selected so that the effect of a change in gas temperature is minimized. The test experiment using pure nearly natural-abundance N(2)O samples showed that the site-selective 15N/14N ratios can be measured relative to a reference material with a precision of +/-3 x 10(-4) (+/-0.3 per thousand) in approximately 2 h. Copyright 2002 Elsevier Science B.V.
C/O Ratio as a Dimension for Characterizing Exoplanetary Atmospheres
NASA Astrophysics Data System (ADS)
Madhusudhan, Nikku
2012-10-01
Until recently, infrared observations of exoplanetary atmospheres have typically been interpreted using models that assumed solar elemental abundances. With the chemical composition fixed, attempts have been made to classify hot Jupiter atmospheres on the basis of stellar irradiation. However, recent observations have revealed deviations from predictions based on such classification schemes, and chemical compositions retrieved from some data sets have also indicated non-solar abundances. The data require a two-dimensional (2D) characterization scheme with dependence on both irradiation and chemistry. In this work, we suggest the carbon-to-oxygen (C/O) ratio as an important second dimension for characterizing exoplanetary atmospheres. In hot-hydrogen-dominated atmospheres, the C/O ratio critically influences the relative concentrations of several spectroscopically dominant species. Between a C/O of 0.5 (solar value) and 2, the H2O and CH4 abundances can vary by several orders of magnitude in the observable atmosphere, and new hydrocarbon species such as HCN and C2H2 become prominent for C/O >= 1, while the CO abundance remains almost unchanged. Furthermore, a C/O >= 1 can preclude a strong thermal inversion due to TiO and VO in a hot Jupiter atmosphere, since TiO and VO are naturally underabundant for C/O >= 1. We, therefore, suggest a new 2D classification scheme for hydrogen-dominated exoplanetary atmospheres with irradiation (or temperature) and C/O ratio as the two dimensions. We define four classes in this 2D space (O1, O2, C1, and C2) with distinct chemical, thermal, and spectral properties. Based on the most recent observations, we characterize the thermal structure and C/O ratios of six hot Jupiters (XO-1b, CoRoT-2b, WASP-14b, WASP-19b, WASP-33b, and WASP-12b) in the framework of our proposed 2D classification scheme. While the data for several systems in our sample are consistent with C-rich atmospheres, new observations are required to conclusively
Gangwar, Manali; Sood, Hemant; Chauhan, Rajinder Singh
2016-04-01
Jatropha curcas, has been projected as a major source of biodiesel due to high seed oil content (42 %). A major roadblock for commercialization of Jatropha-based biodiesel is low seed yield per inflorescence, which is affected by low female to male flower ratio (1:25-30). Molecular dissection of female flower development by analyzing genes involved in phase transitions and floral organ development is, therefore, crucial for increasing seed yield. Expression analysis of 42 genes implicated in floral organ development and sex determination was done at six floral developmental stages of a J. curcas genotype (IC561235) with inherently higher female to male flower ratio (1:8-10). Relative expression analysis of these genes was done on low ratio genotype. Genes TFL1, SUP, AP1, CRY2, CUC2, CKX1, TAA1 and PIN1 were associated with reproductive phase transition. Further, genes CUC2, TAA1, CKX1 and PIN1 were associated with female flowering while SUP and CRY2 in female flower transition. Relative expression of these genes with respect to low female flower ratio genotype showed up to ~7 folds increase in transcript abundance of SUP, TAA1, CRY2 and CKX1 genes in intermediate buds but not a significant increase (~1.25 folds) in female flowers, thereby suggesting that these genes possibly play a significant role in increased transition towards female flowering by promoting abortion of male flower primordia. The outcome of study has implications in feedstock improvement of J. curcas through functional validation and eventual utilization of key genes associated with female flowering.
The relative importance of disturbance and exotic-plant abundance in California coastal sage scrub
Fleming, G.M.; Diffendorfer, J.E.; Zedler, P.H.
2009-01-01
Many ecosystems of conservation concern require some level of disturbance to sustain their species composition and ecological function. However, inappropriate disturbance regimes could favor invasion or expansion of exotic species. In southern California coastal sage scrub (CSS) fire is a natural disturbance, but because of human influence, frequencies may now be unnaturally high. Other anthropogenic disturbances such as grazing also occur in reserve areas. Managers charged with imposing or tolerating fire or other disturbance within their reserves are concerned that habitat quality may be degraded by an increasing abundance of exotic plants. We used vegetation monitoring data from Camp Pendleton, California, USA, to assess the correlation between past disturbances (frequent fire, agriculture, or grazing and mechanical disturbances) and current exotic species abundance in CSS. We found that disturbance history was only modestly related to exotic abundance overall, but fire frequency showed the strongest association. We also examined whether cover and richness of various native plant life forms (woody species, perennial herbs, and annual herbs) were more strongly influenced by disturbance history or by exotic-plant abundance. Native plant responses varied among life forms, but woody species and annual herbs were generally more strongly and negatively associated with exotic abundance than with disturbance. Effective CSS conservation will require developing means to curb the negative impacts of exotic plants, which may abound with or without severe or recent disturbance. Additionally, more focus should be given to understory herbs showing sensitivity to invasion. Though understudied, native herbs comprise the greatest portion of plant diversity in CSS and are critical to preservation of the community as a whole. ?? 2009 by the Ecological Society of America.
Relative foraminiferan abundance as an indicator of seagrass sediment health:
NASA Astrophysics Data System (ADS)
Cajandig, P.; Quiros, A.; Nolan, H.; Tallman, R.; Cooper, N.; Ayala, J.; Courtier, C.
2013-12-01
Authors: Patrick Cajandig*, Jose Ayala**, Nathaniel Cooper**, Catherine Courtier**, Hannah Nolan**, Rachelle Tallman**, T.E. Angela L. Quiros** * Davis High-School CA, **University of California Santa Cruz, Ecology and Evolutionary Biology Department Seagrasses are a key component in coastal ecosystems. Found in shallow marine environments, they make a large contribution to coastal ecosystem health by sustaining water quality, stabilizing the sea bottom, and providing habitat as well as food for other organisms. Seagrasses accumulate tiny grains of sediment, increasing water clarity. Just like barren hills are prone to erosion compared to vegetated, rooted down hills, we find a similar situation in the ocean. Seagrasses have broad roots that extend vertically and horizontally to help stabilize the seabed. Seagrasses support a whole ecosystem, because some organisms feed off of the seagrass alone, while others feed off the inhabitants of the seagrass. The quality of sediment is a vital part of seagrass health, just like nutrient rich soils are important to land plants. But what in seagrass sediment is a good indication of health? We hypothesize that seagrass health measures such as percent cover and seagrass species diversity are related to the abundance of foraminiferans relative to other seagrass sediment components. My mentor, T. E. Angela L. Quiros, from the University of California, Santa Cruz (UCSC), collected the sediment samples from seagrass beds in the Philippines. Samples were dried and brought to UCSC for sediment sieving. We used different sized sieves to sort the sediment. These sieves ranged from coarse to very fine sieves (Phi -2.0 (coarse) through +3.0 (fine) going in 0.5 intervals on a log scale). We weighed the sediment that was caught in each tray and separated them into bags of different size classes. To analyze each sample, we subsampled four size classes (Phi's -2.0, -1.5,-1.0, 0.0), and used a dissecting scope to identify and then weigh the
Mantle rare gas relative abundances in a steady-state mass transport model
NASA Technical Reports Server (NTRS)
Porcelli, D.; Wasserburg, G. J.
1994-01-01
A model for He and Xe was presented previously which incorporates mass transfer of rare gases from an undegassed lower mantle (P) and the atmosphere into a degassed upper mantle (D). We extend the model to include Ne and Ar. Model constraints on rare gas relative abundances within P are derived. Discussions of terrestrial volatile acquisition have focused on the rare gas abundance pattern of the atmosphere relative to meteoritic components, and the pattern of rare gases still trapped in the Ear,th is important in identifying volatile capture and loss processes operating during Earth formation. The assumptions and principles of the model are discussed in Wasserburg and Porcelli (this volume). For P, the concentrations in P of the decay/nuclear products 4 He, 21 Ne, 40 Ar, and 136 Xe can be calculated from the concentrations of the parent elements U, Th, K, and Pu. The total concentration of the daughter element in P is proportional to the isotopic shifts in P. For Ar, ((40)Ar/(36)Ar)p - ((40)Ar/(36)Ar)o =Delta (exp 40) p= 40 Cp/(exp 36)C where(i)C(sub j) the concentration of isotope i in j. In D, isotope compositions are the result of mixing rare gases from P, decay/nuclear products generated in the upper mantle, and subducted rare gases (for Ar and Xe).
Martin, B.A.; Saiki, M.K.
2005-01-01
We assessed the relation between abundance of desert pupfish, Cyprinodon macularius, and selected biological and physicochemical variables in natural and manmade habitats within the Salton Sea Basin. Field sampling in a natural tributary, Salt Creek, and three agricultural drains captured eight species including pupfish (1.1% of the total catch), the only native species encountered. According to Bray-Curtis resemblance functions, fish species assemblages differed mostly between Salt Creek and the drains (i.e., the three drains had relatively similar species assemblages). Pupfish numbers and environmental variables varied among sites and sample periods. Canonical correlation showed that pupfish abundance was positively correlated with abundance of western mosquitofish, Gambusia affinis, and negatively correlated with abundance of porthole livebearers, Poeciliopsis gracilis, tilapias (Sarotherodon mossambica and Tilapia zillii), longjaw mudsuckers, Gillichthys mirabilis, and mollies (Poecilia latipinnaandPoecilia mexicana). In addition, pupfish abundance was positively correlated with cover, pH, and salinity, and negatively correlated with sediment factor (a measure of sediment grain size) and dissolved oxygen. Pupfish abundance was generally highest in habitats where water quality extremes (especially high pH and salinity, and low dissolved oxygen) seemingly limited the occurrence of nonnative fishes. This study also documented evidence of predation by mudsuckers on pupfish. These findings support the contention of many resource managers that pupfish populations are adversely influenced by ecological interactions with nonnative fishes. ?? Springer 2005.
Paukert, C.P.; Makinster, A.S.
2009-01-01
We investigated the spatial variation of flathead catfish (Pylodictis olivaris) relative abundance and growth in the 274 km long Kansas River to determine if population dynamics of catfish are related to urbanization. Electrofishing was conducted at 462 random sites throughout the river in summer, 2005-2006 to collect fish. Relative abundance of age 1 fish (???200mm), subadult (>200-400mm) and adult fish (>400 mm) ranged from 0.34 to 14.67 fish h-1, mean length at age 1 was 165 (range: 128-195) mm total length (TL) and mean length at age 3 was 376 mm TL (range: 293-419mm TL). The proportion of land use within 200 m of the river edge was between 0 and 0.54 urban. River reaches with high relative abundance of age 1 flathead catfish had high relative abundance of subadult and adult catfish. River reaches with fast flathead catfish growth to age 1 had fast growth to age 3. High urban land use and riprap in the riparian area were evident in river reaches near the heavily populated Kansas City and Topeka, Kansas, USA. Reaches with increased number of log jams and islands had decreased riparian agriculture. Areas of low urbanization had faster flathead catfish growth (r = 0.67, p = 0.005). Relative abundance of flathead catfish was higher in more agricultural areas (r = -0.57, p = 0.02). Changes in land use in riverine environments may alter population dynamics of a fish species within a river. Spatial differences in population dynamics need to be considered when evaluating riverine fish populations. Published in 2008 by John Wiley & Sons Ltd.
Wang, C; Liu, Q; Guo, G; Huo, W J; Pei, C X; Zhang, S L; Wang, H
2018-05-01
This study evaluated the effects of dietary concentrate levels and 2-methylbutyrate (2MB) supplementation on performance, ruminal fermentation, bacteria abundance, microbial enzyme activity and urinary excretion of purine derivatives (PD) in steers. Eight ruminally cannulated Simmental steers (12 months of age; 389 ± 3.7 kg of body weight) were used in a replicated 4 × 4 Latin square design with a 2 × 2 factorial arrangement. Moderate-concentrate (400 g/kg diet [MC]) or high-concentrate (600 g/kg diet [HC]) diets were fed with or without 2MB (0 g/day [2MB-] or 15.0 g/day [2MB+]). Dry matter intake and average daily gain increased, but feed conversion ratio decreased with the HC diet or 2MB supplementation. Ruminal pH decreased, but total volatile fatty acid increased with the HC diet or 2MB supplementation. Molar proportion of acetate and acetate-to-propionate ratio decreased with the HC diet, but increased with 2MB supplementation. Propionate molar proportion and ruminal NH 3 -N content increased with the HC diet, but decreased with 2MB supplementation. Neutral detergent fibre degradability decreased with the HC diet, but increased with 2MB supplementation. Crude protein degradability increased with the HC diet or 2MB supplementation. Abundance of Ruminococcus albus, Ruminococcus flavefaciens, Fibrobacter succinogenes and Bufyrivibrio fibrisolvens as well as activities of carboxymethyl cellulase, cellobiase, xylanase and pectinase decreased with the HC diet, but increased with 2MB supplementation. However, abundance of Prevotella ruminicola and Ruminobacter amylophilus as well as activities of α-amylase and protease increased with the HC diet or 2MB supplementation. Total PD excretion also increased with the HC diet or 2MB supplementation. The results suggested that growth performance, ruminal fermentation, CP degradability and total PD excretion increased with increasing dietary concentrate level from 40% to 60% or 2MB supplementation. The
Merriman, J.W.; Boal, C.W.; Bashore, T.L.; Zwank, P.J.; Wester, D.B.
2007-01-01
Some diurnal raptors are frequently observed at prairie dog (Cynomys sp.) colonies. As a result, some military installations have conducted prairie dog control activities to reduce the bird-aircraft strike hazard (BASH) potential of low-flying aircraft. To evaluate the validity of this management strategy, we assessed raptor associations with prairie dog colonies at 2 short-grass prairie study areas: southern Lubbock County, Texas, USA, and Melrose Bombing and Gunnery Range in east-central New Mexico, USA. We quantified diurnal raptors (i.e., Falconiformes) at plots occupied (colony plots) and unoccupied (noncolony plots) by black-tailed prairie dogs (Cynomys ludovicianus) at both sites throughout 2002. We compared the number of individual birds of a given species at colony and noncolony plots within each study area by season. Ferruginous hawks (Buteo regalis) and northern harriers (Circus cyaneus) were more abundant at colony plots, whereas Swainson's hawks (B. swainsoni) and American kestrels (Falco sparverius) were more abundant at noncolony plots. Red-tailed hawk (B. jamaicensis) abundance did not differ between the 2 plot types. Our results suggest prairie dog control as a method of reducing BASH potential may be effective at some sites but may be ineffective or even increase the BASH potential at others. Thus, bird-avoidance models assessing the BASH potential should be conducted on a site-specific basis using information on relative and seasonal abundances of individual raptor species and the relative strike risks they pose to aircraft.
Magnesium Isotope Ratios in ω Centauri Red Giants
NASA Astrophysics Data System (ADS)
Da Costa, G. S.; Norris, John E.; Yong, David
2013-05-01
We have used the high-resolution observations obtained at the Anglo-Australian Telescope with Ultra-High Resolution Facility (R ~ 100,000) and at Gemini-S with b-HROS (R ~ 150,000) to determine magnesium isotope ratios for seven ω Cen red giants that cover a range in iron abundance from [Fe/H] = -1.78 to -0.78 dex, and for two red giants in M4 (NGC 6121). The ω Cen stars sample both the "primordial" (i.e., O-rich, Na- and Al-poor) and the "extreme" (O-depleted, Na- and Al-rich) populations in the cluster. The primordial population stars in both ω Cen and M4 show (25Mg, 26Mg)/24Mg isotopic ratios that are consistent with those found for the primordial population in other globular clusters with similar [Fe/H] values. The isotopic ratios for the ω Cen extreme stars are also consistent with those for extreme population stars in other clusters. The results for the extreme population stars studied indicate that the 26Mg/24Mg ratio is highest at intermediate metallicities ([Fe/H] < -1.4 dex), and for the highest [Al/Fe] values. Further, the relative abundance of 26Mg in the extreme population stars is notably higher than that of 25Mg, in contrast to model predictions. The 25Mg/24Mg isotopic ratio in fact does not show any obvious dependence on either [Fe/H] or [Al/Fe] nor, intriguingly, any obvious difference between the primordial and extreme population stars.
Piazza, Bryan P.; LaPeyre, Megan K.; Keim, B.D.
2010-01-01
Climate creates environmental constraints (filters) that affect the abundance and distribution of species. In estuaries, these constraints often result from variability in water flow properties and environmental conditions (i.e. water flow, salinity, water temperature) and can have significant effects on the abundance and distribution of commercially important nekton species. We investigated links between large-scale climate variability and juvenile brown shrimp Farfantepenaeus aztecus abundance in Breton Sound estuary, Louisiana (USA). Our goals were to (1) determine if a teleconnection exists between local juvenile brown shrimp abundance and the El Niño Southern Oscillation (ENSO) and (2) relate that linkage to environmental constraints that may affect juvenile brown shrimp recruitment to, and survival in, the estuary. Our results identified a teleconnection between winter ENSO conditions and juvenile brown shrimp abundance in Breton Sound estuary the following spring. The physical connection results from the impact of ENSO on winter weather conditions in Breton Sound (air pressure, temperature, and precipitation). Juvenile brown shrimp abundance effects lagged ENSO by 3 mo: lower than average abundances of juvenile brown shrimp were caught in springs following winter El Niño events, and higher than average abundances of brown shrimp were caught in springs following La Niña winters. Salinity was the dominant ENSO-forced environmental filter for juvenile brown shrimp. Spring salinity was cumulatively forced by winter river discharge, winter wind forcing, and spring precipitation. Thus, predicting brown shrimp abundance requires incorporating climate variability into models.
Lemay, Matthew A; Russello, Michael A
2014-11-04
Understanding the distribution and abundance of pathogens can provide insight into the evolution and ecology of their host species. Previous research in kokanee, the freshwater form of sockeye salmon (Oncorhynchus nerka), found evidence that populations spawning in streams may experience a greater pathogen load compared with populations that spawn on beaches. In this study we tested for differences in the abundance and diversity of the gram-negative bacteria, Flavobacterium spp., infecting tissues of kokanee in both of these spawning habitats (streams and beaches). Molecular assays were carried out using primers designed to amplify a ~200 nucleotide region of the gene encoding the ATP synthase alpha subunit (AtpA) within the genus Flavobacterium. Using a combination of DNA sequencing and quantitative PCR (qPCR) we compared the diversity and relative abundance of Flavobacterium AtpA amplicons present in DNA extracted from tissue samples of kokanee collected from each spawning habitat. We identified 10 Flavobacterium AtpA haplotypes among the tissues of stream-spawning kokanee and seven haplotypes among the tissues of beach-spawning kokanee, with only two haplotypes shared between spawning habitats. Haplotypes occurring in the same clade as F. psychrophilum were the most prevalent (92% of all reads, 60% of all haplotypes), and occurred in kokanee from both spawning habitats (streams and beaches). Subsequent qPCR assays did not find any significant difference in the relative abundance of Flavobacterium AtpA amplicons between samples from the different spawning habitats. We confirmed the presence of Flavobacterium spp. in both spawning habitats and found weak evidence for increased Flavobacterium diversity in kokanee sampled from stream-spawning sites. However, the quantity of Flavobacterium DNA did not differ between spawning habitats. We recommend further study aimed at quantifying pathogen diversity and abundance in population-level samples of kokanee combined with
Determination of the calcium elemental abundance for 43 flares from SMM-XRP solar X-ray spectra
NASA Astrophysics Data System (ADS)
Lemen, J. R.; Sylwester, J.; Bentley, R. D.
The helium and lithium-like X-ray transitions of Ca XVIII-XIX have been used to make an absolute measurement of the coronal calcium elemental abundance relative to hydrogen (ACa) in solar flares. Cooling phase spectra of 43 flares obtained in channel 1 of the Bent Crystal Spectrometer on the Solar Maximum Mission have been analyzed. The abundance is determined from the intensity ratio of the Ca XIX resonance line (1S0 - 1P1) and nearby continuum. Attempts to correlate the ACa measurements with other observable features are discussed.
NASA Astrophysics Data System (ADS)
Ge, Tida; Wei, Xiaomeng; Wu, Jinshui
2017-04-01
The addition of phosphorus to P-limited soils has been shown to cause a marked increase in the loss of gaseous N. The reasons for this remain unclear but linked nutrient cycling in the rhizosphere (C:N:P) leading to enhanced nitrification and denitrification have been proposed. We investigated the impact of adding P to P-limited soils on the dynamics of soil N-cycle functional genes. Rice seedlings were planted in P poor soils and incubated under different water conditions with or without P application. The abundance of ammonia-oxidizing bacteria and archaea in the rhizosphere and bulk soil were quantified by Real Time PCR (qPCR) using amoA gene abundance. Results showed that P addition resulted in a decrease in soil NH4+ content and a reduction in the the abundance of ammonia-oxidizing bacteria (AOB). There was little measurable effect on ammonia-oxidizing archaea (AOA). As expected from the marked increase in gaseous N loss, the relative abundances of the four functional genes (narG nirK, nirS, nosZ) increased following P application. This is thought to be a consequence of reducing the impact of P limitation on denitrifying bacteria in the bulk soil. The experimental design used allowed us to deteremine whether the gene responses to P addition in the rhizosphere (where the molar ratios of C:N:P were expected to differ) were different from those of the bulk soil. This 'rhizosphere effect' was weakened for ammonia oxidizing functional genes and enhanced for denitrifying funcational genes by P application, resulted in a greater abundance of AOB (amoA gene) and lower amounts of nirK, nirS and nosZ in rhizosphere soil. The work reported here shows the impact of available P in regulating gaseous N loss from soil and demonstrates the importance of stoichiometry and balanced nutrient availability on the fertilization and management of agricultural soils.
NASA Astrophysics Data System (ADS)
McNeil, W. J.
1997-09-01
Metals in the Earth's atmosphere are of interest and importance for several reasons. Emission lines from the sodium layer are used for wave front corrections in imaging space objects. The ionospheric metals present background contamination for remote sensing and tracking of space- born objects. Ionization during meteor showers may also interfere with communications. Although it is generally accepted that extraterrestrial material is the source of metals in the atmospheric, the relative abundances of mesospheric metals and ions present us with a conundrum. Lidar observations have consistently shown that the abundances of neutral metals in the atmospheric and the abundances of these metals in the meteoric material that falls to earth are significantly disproportionate. For example, the column density of neutral sodium is perhaps two orders of magnitude larger than that of calcium, while the abundances in meteorites are approximately equal. To complicate matters further, ion mass spectroscopy has shown that the abundances of the meteoric ions match reasonably well those in the meteorites. We present here a model that attempts to address these discrepancies. At the heart of the model is the concept of differential ablation, which suggests that more volatile metals sublimate earlier in the descent of a cosmic dust particle than do the less volatile components. The modeling is carried out comprehensively, beginning with the heating and vaporization of the dust particles. The vaporization rate is computed as a function of altitude from an ensemble of particles to give a deposition function which is then injected into a fully time-dependent kinetic code which allows for vertical diffusion and includes diurnal dependence through both the models of the major atmospheric components and through transport of the ions due to electric fields.
IUE/IRAS studies of metal abundances and infrared cirrus
NASA Technical Reports Server (NTRS)
Vansteenberg, M. E.; Shull, J. M.
1986-01-01
A survey is reported of interstellar densities, abundances, and cloud structure in the Galaxy, using the IUE and IRAS satellites. Heavy element depletions are discussed along with their correlations with mean density, reddening, and galactic location. Interesting correlations between the Fe/Si abundance ratio and the infrared diffuse cirrus is also reported, which may provide information on the history and formation of grains in the galactic halo.
Quantifying the relative risk of sex offenders: risk ratios for static-99R.
Hanson, R Karl; Babchishin, Kelly M; Helmus, Leslie; Thornton, David
2013-10-01
Given the widespread use of empirical actuarial risk tools in corrections and forensic mental health, it is important that evaluators and decision makers understand how scores relate to recidivism risk. In the current study, we found strong evidence for a relative risk interpretation of Static-99R scores using 8 samples from Canada, United Kingdom, and Western Europe (N = 4,037 sex offenders). Each increase in Static-99R score was associated with a stable and consistent increase in relative risk (as measured by an odds ratio or hazard ratio of approximately 1.4). Hazard ratios from Cox regression were used to calculate risk ratios that can be reported for Static-99R. We recommend that evaluators consider risk ratios as a useful, nonarbitrary metric for quantifying and communicating risk information. To avoid misinterpretation, however, risk ratios should be presented with recidivism base rates.
Elemental and Molecular Relative Abundances in the Ejecta of Eta Carinae
NASA Technical Reports Server (NTRS)
Kober, G. V.; Gull, T. R.; Nielsen, K.; Bruhweiler, F.; Verner, K.; Stahl, O.; Weis, K.; Bomans, D.
2006-01-01
We are measuring relative elemental abundances for the ejecta in the line of sight from Eta Carinae using high dispersion spectroscopy with the HST/STIS and the VLT/UVES. While multiple velocity components have been identified, we focus on the -513 and -146 km/s components originating from the Homunculus and the Little Homunculus. Complicating factors are the complex nebular structures in the immediate vicinity of the bright, massive star: the very bright emission structures, Weigelt blobs B, C and D, the broad, clumpy structures of the extended wind apparently not photoionized by Eta Car B, and general scattered starlight from the extended wind and the dusty core of the circumstellar material. We have used the 3050 to 3160A region of overlap between STIS and UVES to intercompare equivalent widths of absorption lines to estimate the 'contributing factor', namely the amount of light originating from the star compared to nebular structures. While the extracted STIS spectra are from 0.1" wide aperture, the UVES spectra are limited by the 1" seeing conditions. Curiously we find that the scattering contribution in the UVES spectra changes with time, apparently with orbital phase of the 5.54-year period. This indicates that the dust may be modified by changes in the central source with phase. The noticeable drop in scattered light appears to occur about 1.7 years (phase 0.35) after the spectroscopic minimum. Relative abundances of iron peak elements and some molecules will be estimated. Observations in this study were accomplished with HST through STSci and with VLT through ESO and funded under STIS GTO resources.
Use of motor abundance in old adults in the regulation of a narrow-based stance.
Hsu, Wei-Li; Lin, Kwan-Hwa; Yang, Rong-Sen; Cheng, Chih-Hsiu
2014-02-01
The ability to maintain stable balance while standing decreases with age. The body must coordinate multiple joints using "freeze" or "free" strategy, or a combination of both to ensure balance stability. The purpose of this study was to examine age-related changes in the use of motor abundance during upright stance on a narrow base without visual input. Uncontrolled manifold (UCM) analysis was used to decompose the movement variability of joints into goal-equivalent variability (GEV) and non-goal-equivalent variability (NGEV). The ratio between GEV and NGEV (UCM(ratio)) quantifies the joint coordination related to postural stability, and a high UCM(ratio) value indicates flexible control of joints. To perform balance tests, participants in this study (healthy young and old adults, 20 each) were asked to stand on a flat platform and on narrow wooden blocks with their eyes open and then eyes closed. In upright balance tests, both old and young adults maintained postural stability. GEV was greater than NGEV across all participants and conditions. However, GEV was higher in the young adults than in the old adults, whereas NGEV was higher in the old adults than in the young adults. Therefore, the old adults exhibited a lower UCM(ratio) than the young adults. The old adults were unable to exploit motor abundance and used a less flexible multi-joint coordination pattern to achieve stable balance. The UCM(ratio) value reflects the quality of postural control and can be used for assessing joint coordination in balance disorders.
Lantry, Brian F.; Adams, Jean; Christie, Gavin; Schaner, Teodore; Bowlby, James; Keir, Michael; Lantry, Jana; Sullivan, Paul; Bishop, Daniel; Treska, Ted; Morrison, Bruce
2015-01-01
We examined how attack frequency by sea lampreys on fishes in Lake Ontario varied in response to sea lamprey abundance and preferred host abundance (lake trout > 433 mm). For this analysis we used two gill net assessment surveys, one angler creel survey, three salmonid spawning run datasets, one adult sea lamprey assessment, and a bottom trawl assessment of dead lake trout. The frequency of fresh sea lamprey marks observed on lake trout from assessment surveys was strongly related to the frequency of sea lamprey attacks observed on salmon and trout from the creel survey and spawning migrations. Attack frequencies on all salmonids examined were related to the ratio between the abundances of adult sea lampreys and lake trout. Reanalysis of the susceptibility to sea lamprey attack for lake trout strains stocked into Lake Ontario reaffirmed that Lake Superior strain lake trout were among the most and Seneca Lake strain among the least susceptible and that Lewis Lake strain lake trout were even more susceptible than the Superior strain. Seasonal attack frequencies indicated that as the number of observed sea lamprey attacks decreased during June–September, the ratio of healing to fresh marks also decreased. Simulation of the ratios of healing to fresh marks indicated that increased lethality of attacks by growing sea lampreys contributed to the decline in the ratios and supported laboratory studies about wound healing duration.
Oxygen abundances in halo stars
NASA Astrophysics Data System (ADS)
Bessell, Michael S.; Sutherland, Ralph S.; Ruan, Kui
1991-12-01
The present study determines the oxygen abundance for a sample of metal-poor G dwarfs by analysis of OH lines between 3080 and 3200 A and the permitted high-excitation far-red O I triple. The oxygen abundances determined from the low-excitation OH lines are up to 0.55 dex lower than those measured from the high-excitation O I lines. The abundances for the far-red O I triplet lines agree with those rederived from Abia and Rebolo (1989), and the abundances from the OH lines in dwarfs and giants are in agreement with the rederived O abundances of Barbuy (1988) and others from the forbidden resonance O I line. Because the chi = 0.1.7 eV OH lines are formed in the same layers as the majority of Fe, Ti, and other neutral metal lines used for abundance analyses, it is argued that the OH lines and the forbidden O I line yield the true oxygen abundances relative to the metals.
Climatic effects on mosquito abundance in Mediterranean wetlands
2014-01-01
Background The impact of climate change on vector-borne diseases is highly controversial. One of the principal points of debate is whether or not climate influences mosquito abundance, a key factor in disease transmission. Methods To test this hypothesis, we analysed ten years of data (2003–2012) from biweekly surveys to assess inter-annual and seasonal relationships between the abundance of seven mosquito species known to be pathogen vectors (West Nile virus, Usutu virus, dirofilariasis and Plasmodium sp.) and several climatic variables in two wetlands in SW Spain. Results Within-season abundance patterns were related to climatic variables (i.e. temperature, rainfall, tide heights, relative humidity and photoperiod) that varied according to the mosquito species in question. Rainfall during winter months was positively related to Culex pipiens and Ochlerotatus detritus annual abundances. Annual maximum temperatures were non-linearly related to annual Cx. pipiens abundance, while annual mean temperatures were positively related to annual Ochlerotatus caspius abundance. Finally, we modelled shifts in mosquito abundances using the A2 and B2 temperature and rainfall climate change scenarios for the period 2011–2100. While Oc. caspius, an important anthropophilic species, may increase in abundance, no changes are expected for Cx. pipiens or the salt-marsh mosquito Oc. detritus. Conclusions Our results highlight that the effects of climate are species-specific, place-specific and non-linear and that linear approaches will therefore overestimate the effect of climate change on mosquito abundances at high temperatures. Climate warming does not necessarily lead to an increase in mosquito abundance in natural Mediterranean wetlands and will affect, above all, species such as Oc. caspius whose numbers are not closely linked to rainfall and are influenced, rather, by local tidal patterns and temperatures. The final impact of changes in vector abundance on disease frequency
Chemical Abundances of Hydrostatic and Explosive Alpha-elements in Sagittarius Stream Stars
NASA Astrophysics Data System (ADS)
Carlin, Jeffrey L.; Sheffield, Allyson A.; Cunha, Katia; Smith, Verne V.
2018-05-01
We analyze chemical abundances of stars in the Sagittarius (Sgr) tidal stream using high-resolution Gemini+GRACES spectra of 42 members of the highest surface-brightness portions of both the trailing and leading arms. Targets were chosen using a 2MASS+WISE color–color selection, combined with the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) radial velocities. In this Letter, we analyze [Fe/H] and α-elements produced by both hydrostatic (O, Mg) and explosive (Si, Ca, Ti) nucleosynthetic processes. The average [Fe/H] for our Sgr stream stars is lower than that for stars in the Sgr core, and stars in the trailing and leading arms show systematic differences in [Fe/H]. Both hydrostatic and explosive elements are depleted relative to Milky Way (MW) disk and halo stars, with a larger gap between the MW trend and Sgr stars for the hydrostatic elements. Chemical abundances of Sgr stream stars show similar patterns to those measured in the core of the Sgr dSph. We explore the ratio of hydrostatic to explosive α-elements [α h/ex] (which we refer to as the “HEx ratio”). Our observed HEx ratio trends for Sgr debris are deficient relative to MW stars. Via simple chemical evolution modeling, we show that these HEx ratio patterns are consistent with a Sgr IMF that lacks the most massive stars. This study provides a link between the chemical properties in the intact Sgr core and the significant portion of the Sgr system’s luminosity that is estimated to currently reside in the streams.
Are the Formation and Abundances of Metal-poor Stars the Result of Dust Dynamics?
DOE Office of Scientific and Technical Information (OSTI.GOV)
Hopkins, Philip F.; Conroy, Charlie, E-mail: phopkins@caltech.edu
Large dust grains can fluctuate dramatically in their local density, relative to the gas, in neutral turbulent disks. Small, high-redshift galaxies (before reionization) represent ideal environments for this process. We show via simple arguments and simulations that order-of-magnitude fluctuations are expected in local abundances of large grains (>100 Å) under these conditions. This can have important consequences for star formation and stellar metal abundances in extremely metal-poor stars. Low-mass stars can form in dust-enhanced regions almost immediately after some dust forms even if the galaxy-average metallicity is too low for fragmentation to occur. We argue that the metal abundances ofmore » these “promoted” stars may contain interesting signatures as the CNO abundances (concentrated in large carbonaceous grains and ices) and Mg and Si (in large silicate grains) can be enhanced and/or fluctuate almost independently. Remarkably, the otherwise puzzling abundance patterns of some metal-poor stars can be well fit by standard IMF-averaged core-collapse SNe yields if we allow for fluctuating local dust-to-gas ratios. We also show that the observed log-normal distribution of enhancements in pure SNe yields, shows very large enhancements and variations up to factors of ≳100 as expected in the dust-promoted model, preferentially in the [C/Fe]-enhanced metal-poor stars. Together, this suggests that (1) dust exists in second-generation star formation, (2) local dust-to-gas ratio fluctuations occur in protogalaxies and can be important for star formation, and (3) the light element abundances of these stars may be affected by the local chemistry of dust where they formed, rather than directly tracing nucleosynthesis from earlier populations.« less
The UCSD HIRES/Keck I Damped Lyα Abundance Database. II. The Implications
NASA Astrophysics Data System (ADS)
Prochaska, Jason X.; Wolfe, Arthur M.
2002-02-01
We present a comprehensive analysis of the damped Lyα (DLA) abundance database presented in the first paper of this series. This database provides a homogeneous set of abundance measurements for many elements including Si, Cr, Ni, Zn, Fe, Al, S, Co, O, and Ar from 38 DLA systems with zabs>1.5. With little exception, these DLA systems exhibit very similar relative abundances. There is no significant correlation in X/Fe with [Fe/H] metallicity, and the dispersion in X/Fe is small at all metallicity. We search the database for trends indicative of dust depletion and in a few cases find strong evidence. Specifically, we identify a correlation between [Si/Ti] and [Zn/Fe] which is unambiguous evidence for depletion. Following Hou and colleagues, we present [X/Si] abundances against [Si/H]+logN(HI) and note trends of decreasing X/Si with increasing [Si/H]+logN(HI) which argue for dust depletion. Similarly, comparisons of [Si/Fe] and [Si/Cr] against [Si/H] indicate significant depletion at [Si/H]>-1 but suggest essentially dust-free damped systems at [Si/H]<-1.5 dex. We present a discussion on the nucleosynthetic history of the DLA systems by focusing on abundance patterns which are minimally affected by dust depletion. We find [Si/Fe]-->0.25 dex as [Zn/Fe]-->0 and that the [Si/Fe] values exhibit a plateau of ~0.3 dex at [Si/H]<-1.5 dex. Together these trends indicate significant α-enrichment in the DLA systems at low metallicity, an interpretation further supported by the observed O/Fe, S/Fe, and Ar/Fe ratios. Comparing the relative abundances of the Fe peak elements, we identify important offsets from solar relative abundances for Cr, Ni, and Fe which suggest variations in nucleosynthesis along the Fe peak. Finally, the DLA systems exhibit a modest odd-even effect revealed by Si/Al, [Si/Al]~0.4 dex, which is significantly smaller than values observed in Galactic halo stars of comparable metallicity. These observations present strong evidence that the DLA systems and
MAGNESIUM ISOTOPE RATIOS IN {omega} CENTAURI RED GIANTS
DOE Office of Scientific and Technical Information (OSTI.GOV)
Da Costa, G. S.; Norris, John E.; Yong, David
2013-05-20
We have used the high-resolution observations obtained at the Anglo-Australian Telescope with Ultra-High Resolution Facility (R {approx} 100,000) and at Gemini-S with b-HROS (R {approx} 150,000) to determine magnesium isotope ratios for seven {omega} Cen red giants that cover a range in iron abundance from [Fe/H] = -1.78 to -0.78 dex, and for two red giants in M4 (NGC 6121). The {omega} Cen stars sample both the ''primordial'' (i.e., O-rich, Na- and Al-poor) and the ''extreme'' (O-depleted, Na- and Al-rich) populations in the cluster. The primordial population stars in both {omega} Cen and M4 show ({sup 25}Mg, {sup 26}Mg)/{sup 24}Mgmore » isotopic ratios that are consistent with those found for the primordial population in other globular clusters with similar [Fe/H] values. The isotopic ratios for the {omega} Cen extreme stars are also consistent with those for extreme population stars in other clusters. The results for the extreme population stars studied indicate that the {sup 26}Mg/{sup 24}Mg ratio is highest at intermediate metallicities ([Fe/H] < -1.4 dex), and for the highest [Al/Fe] values. Further, the relative abundance of {sup 26}Mg in the extreme population stars is notably higher than that of {sup 25}Mg, in contrast to model predictions. The {sup 25}Mg/{sup 24}Mg isotopic ratio in fact does not show any obvious dependence on either [Fe/H] or [Al/Fe] nor, intriguingly, any obvious difference between the primordial and extreme population stars.« less
CARBON-TO-OXYGEN RATIOS IN M DWARFS AND SOLAR-TYPE STARS
DOE Office of Scientific and Technical Information (OSTI.GOV)
Nakajima, Tadashi; Sorahana, Satoko, E-mail: tadashi.nakajima@nao.ac.jp, E-mail: sorahana@astron.s.u-tokyo.ac.jp
It has been suggested that high C/O ratios (>0.8) in circumstellar disks lead to the formation of carbon-dominated planets. Based on the expectation that elemental abundances in the stellar photospheres give the initial abundances in the circumstellar disks, the frequency distributions of C/O ratios of solar-type stars have been obtained by several groups. The results of these investigations are mixed. Some find C/O > 0.8 in more than 20% of stars, and C/O > 1.0 in more than 6%. Others find C/O > 0.8 in none of the sample stars. These works on solar-type stars are all differential abundance analysesmore » with respect to the Sun and depend on the adopted C/O ratio in the Sun. Recently, a method of molecular line spectroscopy of M dwarfs, in which carbon and oxygen abundances are derived respectively from CO and H{sub 2}O lines in the K band, has been developed. The resolution of the K- band spectrum is 20,000. Carbon and oxygen abundances of 46 M dwarfs have been obtained by this nondifferential abundance analysis. Carbon-to-oxygen ratios in M dwarfs derived by this method are more robust than those in solar-type stars derived from neutral carbon and oxygen lines in the visible spectra because of the difficulty in the treatment of oxygen lines. We have compared the frequency distribution of C/O distributions in M dwarfs with those of solar-type stars and have found that the low frequency of high-C/O ratios is preferred.« less
Iron Abundance in the Prototype PG 1159 Star, GW Vir Pulsator PG 1159-035, and Related Objects
NASA Technical Reports Server (NTRS)
Werner, K.; Rauch, T.; Kruk, J. W.; Kurucz, R. L.
2011-01-01
We performed an iron abundance determination of the hot, hydrogen deficient post-AGB star PG 1159-035. which is the prototype of the PG 1159 spectral class and the GW Vir pulsators, and of two related objects (PG 1520+525, PG 1144+005), based on the first detection of Fe VIII lines in stellar photospheres. In another PG 1159 star. PG 1424+535. we detect Fe VII lines. In all four stars, each within T(sub eff) = 110,000-150,000 K, we find a solar iron abundance. This result agrees with our recent abundance analysis of the hottest PG 1159 stars (T(sub eff) = 150,000-200,000 K) that exhibit Fe x lines. On the whole, we find that the PG 1159 stars are not significantly iron deficient, in contrast to previous notions.
Absolute Isotopic Abundance Ratios and the Accuracy of Δ47 Measurements
NASA Astrophysics Data System (ADS)
Daeron, M.; Blamart, D.; Peral, M.; Affek, H. P.
2016-12-01
Conversion from raw IRMS data to clumped isotope anomalies in CO2 (Δ47) relies on four external parameters: the (13C/12C) ratio of VPDB, the (17O/16O) and (18O/16O) ratios of VSMOW (or VPDB-CO2), and the slope of the triple oxygen isotope line (λ). Here we investigate the influence that these isotopic parameters exert on measured Δ47 values, using real-world data corresponding to 7 months of measurements; simulations based on randomly generated data; precise comparisons between water-equilibrated CO2 samples and between carbonate standards believed to share quasi-identical Δ47 values; reprocessing of two carbonate calibration data sets with different slopes of Δ47 versus T. Using different sets of isotopic parameters generally produces systematic offsets as large as 0.04 ‰ in final Δ47 values. What's more, even using a single set of isotopic parameters can produce intra- and inter-laboratory discrepancies in final Δ47 values, if some of these parameters are inaccurate. Depending on the isotopic compositions of the standards used for conversion to "absolute" values, these errors should correlate strongly with either δ13C or δ18O, or more weakly with both. Based on measurements of samples expected to display identical Δ47 values, such as 25°C water-equilibrated CO2 with different carbon and oxygen isotope compositions, or high-temperature standards ETH-1 and ETH-2, we conclude that the isotopic parameters used so far in most clumped isotope studies produces large, systematic errors controlled by the relative bulk isotopic compositions of samples and standards, which should be one of the key factors responsible for current inter-laboratory discrepancies. By contrast, the isotopic parameters of Brand et al. [2010] appear to yield accurate Δ47 values regardless of bulk isotopic composition. References:Brand, Assonov and Coplen [2010] http://dx.doi.org/10.1351/PAC-REP-09-01-05
C/O RATIO AS A DIMENSION FOR CHARACTERIZING EXOPLANETARY ATMOSPHERES
DOE Office of Scientific and Technical Information (OSTI.GOV)
Madhusudhan, Nikku, E-mail: Nikku.Madhusudhan@yale.edu; Department of Astronomy, Yale University, New Haven, CT 06511
2012-10-10
Until recently, infrared observations of exoplanetary atmospheres have typically been interpreted using models that assumed solar elemental abundances. With the chemical composition fixed, attempts have been made to classify hot Jupiter atmospheres on the basis of stellar irradiation. However, recent observations have revealed deviations from predictions based on such classification schemes, and chemical compositions retrieved from some data sets have also indicated non-solar abundances. The data require a two-dimensional (2D) characterization scheme with dependence on both irradiation and chemistry. In this work, we suggest the carbon-to-oxygen (C/O) ratio as an important second dimension for characterizing exoplanetary atmospheres. In hot-hydrogen-dominated atmospheres,more » the C/O ratio critically influences the relative concentrations of several spectroscopically dominant species. Between a C/O of 0.5 (solar value) and 2, the H{sub 2}O and CH{sub 4} abundances can vary by several orders of magnitude in the observable atmosphere, and new hydrocarbon species such as HCN and C{sub 2}H{sub 2} become prominent for C/O {>=} 1, while the CO abundance remains almost unchanged. Furthermore, a C/O {>=} 1 can preclude a strong thermal inversion due to TiO and VO in a hot Jupiter atmosphere, since TiO and VO are naturally underabundant for C/O {>=} 1. We, therefore, suggest a new 2D classification scheme for hydrogen-dominated exoplanetary atmospheres with irradiation (or temperature) and C/O ratio as the two dimensions. We define four classes in this 2D space (O1, O2, C1, and C2) with distinct chemical, thermal, and spectral properties. Based on the most recent observations, we characterize the thermal structure and C/O ratios of six hot Jupiters (XO-1b, CoRoT-2b, WASP-14b, WASP-19b, WASP-33b, and WASP-12b) in the framework of our proposed 2D classification scheme. While the data for several systems in our sample are consistent with C-rich atmospheres, new
Global abundance of planktonic heterotrophic protists in the deep ocean
Pernice, Massimo C; Forn, Irene; Gomes, Ana; Lara, Elena; Alonso-Sáez, Laura; Arrieta, Jesus M; del Carmen Garcia, Francisca; Hernando-Morales, Victor; MacKenzie, Roy; Mestre, Mireia; Sintes, Eva; Teira, Eva; Valencia, Joaquin; Varela, Marta M; Vaqué, Dolors; Duarte, Carlos M; Gasol, Josep M; Massana, Ramon
2015-01-01
The dark ocean is one of the largest biomes on Earth, with critical roles in organic matter remineralization and global carbon sequestration. Despite its recognized importance, little is known about some key microbial players, such as the community of heterotrophic protists (HP), which are likely the main consumers of prokaryotic biomass. To investigate this microbial component at a global scale, we determined their abundance and biomass in deepwater column samples from the Malaspina 2010 circumnavigation using a combination of epifluorescence microscopy and flow cytometry. HP were ubiquitously found at all depths investigated down to 4000 m. HP abundances decreased with depth, from an average of 72±19 cells ml−1 in mesopelagic waters down to 11±1 cells ml−1 in bathypelagic waters, whereas their total biomass decreased from 280±46 to 50±14 pg C ml−1. The parameters that better explained the variance of HP abundance were depth and prokaryote abundance, and to lesser extent oxygen concentration. The generally good correlation with prokaryotic abundance suggested active grazing of HP on prokaryotes. On a finer scale, the prokaryote:HP abundance ratio varied at a regional scale, and sites with the highest ratios exhibited a larger contribution of fungi molecular signal. Our study is a step forward towards determining the relationship between HP and their environment, unveiling their importance as players in the dark ocean's microbial food web. PMID:25290506
Global abundance of planktonic heterotrophic protists in the deep ocean.
Pernice, Massimo C; Forn, Irene; Gomes, Ana; Lara, Elena; Alonso-Sáez, Laura; Arrieta, Jesus M; del Carmen Garcia, Francisca; Hernando-Morales, Victor; MacKenzie, Roy; Mestre, Mireia; Sintes, Eva; Teira, Eva; Valencia, Joaquin; Varela, Marta M; Vaqué, Dolors; Duarte, Carlos M; Gasol, Josep M; Massana, Ramon
2015-03-01
The dark ocean is one of the largest biomes on Earth, with critical roles in organic matter remineralization and global carbon sequestration. Despite its recognized importance, little is known about some key microbial players, such as the community of heterotrophic protists (HP), which are likely the main consumers of prokaryotic biomass. To investigate this microbial component at a global scale, we determined their abundance and biomass in deepwater column samples from the Malaspina 2010 circumnavigation using a combination of epifluorescence microscopy and flow cytometry. HP were ubiquitously found at all depths investigated down to 4000 m. HP abundances decreased with depth, from an average of 72±19 cells ml(-1) in mesopelagic waters down to 11±1 cells ml(-1) in bathypelagic waters, whereas their total biomass decreased from 280±46 to 50±14 pg C ml(-1). The parameters that better explained the variance of HP abundance were depth and prokaryote abundance, and to lesser extent oxygen concentration. The generally good correlation with prokaryotic abundance suggested active grazing of HP on prokaryotes. On a finer scale, the prokaryote:HP abundance ratio varied at a regional scale, and sites with the highest ratios exhibited a larger contribution of fungi molecular signal. Our study is a step forward towards determining the relationship between HP and their environment, unveiling their importance as players in the dark ocean's microbial food web.
Chemical Abundances of Planetary Nebulae in the Substructures of M31
NASA Astrophysics Data System (ADS)
Fang, Xuan; García-Benito, Rubén; Guerrero, Martín A.; Liu, Xiaowei; Yuan, Haibo; Zhang, Yong; Zhang, Bing
2015-12-01
We present deep spectroscopy of planetary nebulae (PNe) that are associated with the substructures of the Andromeda Galaxy (M31). The spectra were obtained with the Optical System for Imaging and low-intermediate-Resolution Integrated Spectroscopy spectrograph on the 10.4 m Gran Telescopio Canarias. Seven targets were selected for the observations, three in the Northern Spur and four associated with the Giant Stream. The most distant target in our sample, with a rectified galactocentric distance ≥slant 100 kpc, was the first PN discovered in the outer streams of M31. The [O iii] λ4363 auroral line is well detected in the spectra of all targets, enabling electron temperature determination. Ionic abundances are derived based on the [O iii] temperatures, and elemental abundances of helium, nitrogen, oxygen, neon, sulfur, and argon are estimated. The relatively low N/O and He/H ratios, as well as abundance ratios of α-elements, indicate that our target PNe might belong to populations as old as ∼2 Gyr. Our PN sample, including the current seven and the previous three observed by Fang et al., have rather homogeneous oxygen abundances. The study of abundances and the spatial and kinematical properties of our sample leads to the tempting conclusion that their progenitors might belong to the same stellar population, which hints at a possibility that the Northern Spur and the Giant Stream have the same origin. This may be explained by the stellar orbit proposed by Merrett et al. Judging from the position and kinematics, we emphasize that M32 might be responsible for the two substructures. Deep spectroscopy of PNe in M32 will help to assess this hypothesis. Based on observations made with the Gran Telescopio Canarias, installed at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias, in the island of La Palma. These observations are associated with program No. GTC55-14B.
The Carbon Isotope Ratio in Local Molecular Clouds
NASA Astrophysics Data System (ADS)
Goto, Miwa; Usuda, Tomonori; Takato, Naruhisa; Masahiko, Hayashi; Sakamoto, Seiichi; Mitchell, George
We report the carbon isotope ratio in nearby molecular clouds LkHα 101, AFGL 490, and Mon R2 IRS 3. The vibrational transition bands of 12CO ν = 2 ← 0 and 13CO ν = 1 ← 0 were observed with high resolution near-infrared spectroscopy (R = 23,000) to measure the relative abundance of 13CO to 12CO. The isotopic ratios are 12CO/13CO = 1379 (LkHα 101), 8649 (AFGL 490), and 158 (Mon R2 IRS 3), which is twice higher than in the solar neighborhood. The molecular clouds are with high visible extinction (AV = 10 70 mag), well shielded from destructive FUV field. It is questionable that the selective photo-destruction of 13CO plays a major role in biasing isotope ratio. Uncertainty in the Doppler parameters of the unresolved absorption lines, and possible emission filling of fundamental transitions are suspected to account for the high 12CO/13CO ratio. Higher resolution spectroscopy (R ~ 100,000) is the key to go for the accurate measurement of isotope ratio.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Hooper, Cornelia M.; Stevens, Tim J.; Saukkonen, Anna
Measuring changes in protein or organelle abundance in the cell is an essential, but challenging aspect of cell biology. Frequently-used methods for determining organelle abundance typically rely on detection of a very few marker proteins, so are unsatisfactory. In silico estimates of protein abundances from publicly available protein spectra can provide useful standard abundance values but contain only data from tissue proteomes, and are not coupled to organelle localization data. A new protein abundance score, the normalized protein abundance scale (NPAS), expands on the number of scored proteins and the scoring accuracy of lower-abundance proteins in Arabidopsis. NPAS was combinedmore » with subcellular protein localization data, facilitating quantitative estimations of organelle abundance during routine experimental procedures. A suite of targeted proteomics markers for subcellular compartment markers was developed, enabling independent verification of in silico estimates for relative organelle abundance. Estimation of relative organelle abundance was found to be reproducible and consistent over a range of tissues and growth conditions. In silico abundance estimations and localization data have been combined into an online tool, multiple marker abundance profiling, available in the SUBA4 toolbox (http://suba.live).« less
Hooper, Cornelia M.; Stevens, Tim J.; Saukkonen, Anna; ...
2017-10-12
Measuring changes in protein or organelle abundance in the cell is an essential, but challenging aspect of cell biology. Frequently-used methods for determining organelle abundance typically rely on detection of a very few marker proteins, so are unsatisfactory. In silico estimates of protein abundances from publicly available protein spectra can provide useful standard abundance values but contain only data from tissue proteomes, and are not coupled to organelle localization data. A new protein abundance score, the normalized protein abundance scale (NPAS), expands on the number of scored proteins and the scoring accuracy of lower-abundance proteins in Arabidopsis. NPAS was combinedmore » with subcellular protein localization data, facilitating quantitative estimations of organelle abundance during routine experimental procedures. A suite of targeted proteomics markers for subcellular compartment markers was developed, enabling independent verification of in silico estimates for relative organelle abundance. Estimation of relative organelle abundance was found to be reproducible and consistent over a range of tissues and growth conditions. In silico abundance estimations and localization data have been combined into an online tool, multiple marker abundance profiling, available in the SUBA4 toolbox (http://suba.live).« less
Gravett, Michael G.; Jin, Ling; Pavlova, Sylvia I.; Tao, Lin
2012-01-01
Background The rhesus monkey is an important animal model to study human vaginal health to which lactic acid bacteria play a significant role. However, the vaginal lactic acid bacterial species richness and relative abundance in rhesus monkeys is largely unknown. Methods Vaginal swab samples were aseptically obtained from 200 reproductive aged female rhesus monkeys. Following Rogosa agar plating, single bacterial colonies representing different morphotypes were isolated and analyzed for whole-cell protein profile, species-specifc PCR, and 16S rRNA gene sequence. Results A total of 510 Lactobacillus strains of 17 species and one Pediococcus acidilactici were identified. The most abundant species was L. reuteri, which colonized the vaginas of 86% monkeys. L. johnsonii was the second most abundant species, which colonized 36% of monkeys. The majority of monkeys were colonized by multiple Lactobacillus species. Conclusions The vaginas of rhesus monkeys are frequently colonized by multiple Lactobacillus species, dominated by L. reuteri. PMID:22429090
Heavy Element Abundances in Planetary Nebulae from Deep Optical Echelle Spectroscopy
NASA Astrophysics Data System (ADS)
Mashburn, Amanda; Sterling, Nicholas C.; Dinerstein, Harriet L.; Garofali, Kristen; Jensema, Rachael; Turbyfill, Amanda; Wieser, Hannah-Marie N.; Reed, Evan C.; Redfield, Seth
2016-01-01
We present the abundances of neutron(n)-capture elements (atomic number Z > 30) and iron determined from deep optical echelle spectroscopy of 14 Galactic planetary nebulae (PNe). The spectra were obtained with the 2D-coudé spectrograph on the 2.7-m Harlan J. Smith telescope at McDonald Observatory. The abundances of n-capture elements can be enhanced in PNe due to slow n-capture nucleosynthesis in the progenitor asymptotic giant branch (AGB) stars. The high spectral resolution of these data (R = 36,700) allow most n-capture element emission lines to be resolved from other nebular and telluric features. We detect Kr in all of the observed PNe (with multiple ions detected in several objects), while Br, Rb, and Xe were each detected in 4--5 objects. Using the new Kr ionization correction factors (ICFs) of Sterling et al. (2015, ApJS, 218, 25), we find [Kr/O] abundances ranging from 0.05 to 1.1 dex. We utilize approximate ICFs for the other n-capture elements, and find slightly lower enrichments for Br and Rb (-0.1 to 0.7 dex), while Xe is enhanced relative to solar by factors of two to 30. The [Xe/Kr] ratios range from -0.3 to 1.4 dex, indicating a significant range in neutron exposures in PN progenitor stars. Interestingly, the largest [Xe/Kr] ratio is found in the thick-disk PN NGC 6644, which has a lower metallicity than the other observed PNe. We detect iron emission lines in all but one target. Fe can be depleted into dust grains in ionized nebulae, and its abundance thus provides key information regarding dust-to-gas ratios and grain destruction processes. We find that [Fe/O] ranges from -1.3 to -0.7 dex in the observed PNe, a smaller spread of depletion factors than found in recent studies (Delgado-Inglada & Rodriguez 2014, ApJ, 784, 173) though this may be due in part to our smaller sample. These data are part of a larger study of heavy elements in PNe, which will provide more accurate determinations of n-capture element abundances than previous estimates in
Yanagawa, Katsunori; Morono, Yuki; Yoshida-Takashima, Yukari; Eitoku, Masamitsu; Sunamura, Michinari; Inagaki, Fumio; Imachi, Hiroyuki; Takai, Ken; Nunoura, Takuro
2014-04-01
We studied the relationship between viral particle and microbial cell abundances in marine subsurface sediments from three geographically distinct locations in the continental margins (offshore of the Shimokita Peninsula of Japan, the Cascadia Margin off Oregon, and the Gulf of Mexico) and found depth variations in viral abundances among these sites. Viruses in sediments obtained offshore of the Shimokita and in the Cascadia Margin generally decreased with increasing depth, whereas those in sediments from the Gulf of Mexico were relatively constant throughout the investigated depths. In addition, the abundance ratios of viruses to microbial cells notably varied among the sites, ranging between 10(-3) and 10(1) . The subseafloor viral abundance offshore of the Shimokita showed a positive relationship with the microbial cell abundance and the sediment porosity. In contrast, no statistically significant relationship was observed in the Cascadia Margin and the Gulf of Mexico sites, presumably due to the long-term preservation of viruses from enzymatic degradation within the low-porosity sediments. Our observations indicate that viral abundance in the marine subsurface sedimentary environment is regulated not only by in situ production but also by the balance of preservation and decay, which is associated with the regional sedimentation processes in the geological settings. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.
Abundances of carbon-enhanced metal-poor stars as constraints on their formation
NASA Astrophysics Data System (ADS)
Hansen, C. J.; Nordström, B.; Hansen, T. T.; Kennedy, C. R.; Placco, V. M.; Beers, T. C.; Andersen, J.; Cescutti, G.; Chiappini, C.
2016-04-01
Context. An increasing fraction of carbon-enhanced metal-poor (CEMP) stars is found as their iron abundance, [Fe/H], decreases below [Fe/H] =-2.0. The CEMP-s stars have the highest absolute carbon abundances, [C/H], and are thought to owe their enrichment in carbon and the slow neutron-capture (s-process) elements to mass transfer from a former asymptotic giant branch (AGB) binary companion. The most Fe-poor CEMP stars are normally single, exhibit somewhat lower [C/H] than CEMP-s stars, but show no s-process element enhancement (CEMP-no stars). Abundance determinations of CNO offer clues to their formation sites. Aims: Our aim is to use the medium-resolution spectrograph X-Shooter/VLT to determine stellar parameters and abundances for C, N, Sr, and Ba in several classes of CEMP stars in order to further classify and constrain the astrophysical formation sites of these stars. Methods: Atmospheric parameters for our programme stars were estimated from a combination of V-K photometry, model isochrone fits, and estimates from a modified version of the SDSS/SEGUE spectroscopic pipeline. We then used X-Shooter spectra in conjunction with the 1D local thermodynamic equilibrium spectrum synthesis code MOOG, 1D ATLAS9 atmosphere models to derive stellar abundances, and, where possible, isotopic 12C/13C ratios. Results: Abundances (or limits) of C, N, Sr, and Ba are derived for a sample of 27 faint metal-poor stars for which the X-Shooter spectra have sufficient signal-to-noise ratios (S/N). These moderate resolution, low S/N (~10-40) spectra prove sufficient to perform limited chemical tagging and enable assignment of these stars into the CEMP subclasses (CEMP-s and CEMP-no). According to the derived abundances, 17 of our sample stars are CEMP-s and 3 are CEMP-no, while the remaining 7 are carbon-normal. For four CEMP stars, the subclassification remains uncertain, and two of them may be pulsating AGB stars. Conclusions: The derived stellar abundances trace the formation
DAVE CURRIE; JOSEPH M. WUNDERLE JR.; DAVID N. EWERT; ANCILLENO DAVIS; ZEKO MCKENZIE
2005-01-01
We studied winter avian distribution and relative abundance in six common terrestrial broadleaf habitats, selected on a continuum of disturbance from recently disturbed (abandoned plantation) to mature vegetation (tall coppice), on the island of Eleuthera, The Bahamas. During 158-point counts conducted 22 Januaryâ10 March 2003, 1357 individuals were detected,...
Atmospheric 21Ne abundance determined by the Helix-MC Plus mass spectrometer
NASA Astrophysics Data System (ADS)
Honda, M.; Zhang, X.; Phillips, D.; Hamilton, D.; Deerberg, M.; Schwieters, J. B.
2014-12-01
Analyses of noble gas isotopes by multi-collector, high resolution mass spectrometry have the potential to revolutionise applications in the cosmo-geo-sciences. The Helix-MC Plus noble gas mass spectrometer installed at the Australian National University (ANU) is equipped with unique high mass resolution collectors [mass resolution (MR): ~1,800 and mass resolving power (MRP): ~8,000], including fixed axial (Ax), adjustable high mass (H2) and adjustable low mass (L2) detectors. The high mass resolution of the L2, Ax and H2 collectors permits complete separation of 20Ne (measured on L2 detector) from doubly charged interfering 40Ar (required MR of 1,777), 1H19F (MR = 1450), 1H218O (MR = 894) and partial separation of the 21Ne peak (on Ax detector) from interfering 20Ne1H (MR = 3,271), and 22Ne (on H2 detector) from interfering doubly charged CO2 (MR = 6,231). Because of the high MRP of ~8,000, 21Ne can be measured, essentially without interference from 20Ne1H, by setting the magnet position on a 20Ne1H interference-free position. This capability provides an important opportunity to re-evaluate the 21Ne abundance in the atmosphere. Our analyses demonstrate that 20Ne1H contributes ~4% to atmospheric 21Ne measurements, with the corresponding production ratio of 20Ne1H to 20Ne being ~1E-4. We calculate a new atmospheric 21Ne/20Ne ratio of 0.00287 relative to an atmospheric 22Ne/20Ne ratio of 0.102; this new value is distinctly lower than the current IUPAC recommended 21Ne/20Ne value of 0.00298. There are several significant implications ensuing from the newly determined atmospheric 21Ne abundance. For example, in the area of Earth sciences the most critical issue relates to cosmogenic 21Ne surface exposure ages, which involve the calculation of 21Ne concentrations from excess 21Ne, relative to the atmospheric 21Ne/20Ne ratio. For young samples, where cosmogenic 21Ne contents are small and the 21Ne/20Ne ratio is close to the atmospheric value, the revised value could
DOE Office of Scientific and Technical Information (OSTI.GOV)
Johnson, Christian I.; Rich, R. Michael; Kobayashi, Chiaki
2012-04-20
We report chemical abundances of Na, Al, Zr, La, Nd, and Eu for 39 red giant branch (RGB) stars and 23 potential inner disk red clump stars located in Plaut's low-extinction window. We also measure lithium for a super Li-rich RGB star. The abundances were determined by spectrum synthesis of high-resolution (R Almost-Equal-To 25,000), high signal-to-noise (S/N {approx} 50-100 pixel{sup -1}) spectra obtained with the Blanco 4 m telescope and Hydra multifiber spectrograph. For the bulge RGB stars, we find a general increase in the [Na/Fe] and [Na/Al] ratios with increasing metallicity, and a similar decrease in [La/Fe] and [Nd/Fe].more » Additionally, the [Al/Fe] and [Eu/Fe] abundance trends almost identically follow those of the {alpha}-elements, and the [Zr/Fe] ratios exhibit relatively little change with [Fe/H]. The consistently low [La/Eu] ratios of the RGB stars indicate that at least a majority of bulge stars formed rapidly ({approx}<1 Gyr) and before the main s-process could become a significant pollution source. In contrast, we find that the potential inner disk clump stars exhibit abundance patterns more similar to those of the thin and thick disks. Comparisons between the abundance trends at different bulge locations suggest that the inner and outer bulges formed on similar timescales. However, we find evidence of some abundance differences between the most metal-poor and metal-rich stars in various bulge fields. The data also indicate that the halo may have had a more significant impact on the outer bulge initial composition than the inner bulge composition. The [Na/Fe], and to a lesser extent [La/Fe], abundances further indicate that the metal-poor bulge, at least at {approx}1 kpc from the Galactic center, and thick disk may not share an identical chemistry.« less
Origin and abundance of water in carbonaceous asteroids
NASA Astrophysics Data System (ADS)
Marrocchi, Yves; Bekaert, David V.; Piani, Laurette
2018-01-01
The origin and abundance of water accreted by carbonaceous asteroids remains underconstrained, but would provide important information on the dynamic of the protoplanetary disk. Here we report the in situ oxygen isotopic compositions of aqueously formed fayalite grains in the Kaba and Mokoia CV chondrites. CV chondrite bulk, matrix and fayalite O-isotopic compositions define the mass-independent continuous trend (δ17O = 0.84 ± 0.03 × δ18O - 4.25 ± 0.1), which shows that the main process controlling the O-isotopic composition of the CV chondrite parent body is related to isotopic exchange between 16O-rich anhydrous silicates and 17O- and 18O-rich fluid. Similar isotopic behaviors observed in CM, CR and CO chondrites demonstrate the ubiquitous nature of O-isotopic exchange as the main physical process in establishing the O-isotopic features of carbonaceous chondrites, regardless of their alteration degree. Based on these results, we developed a new approach to estimate the abundance of water accreted by carbonaceous chondrites (quantified by the water/rock ratio) with CM (0.3-0.4) ≥ CR (0.1-0.4) ≥ CV (0.1-0.2) > CO (0.01-0.10). The low water/rock ratios and the O-isotopic characteristics of secondary minerals in carbonaceous chondrites indicate they (i) formed in the main asteroid belt and (ii) accreted a locally derived (inner Solar System) water formed near the snowline by condensation from the gas phase. Such results imply low influx of D- and 17O- and 18O-rich water ice grains from the outer part of the Solar System. The latter is likely due to the presence of a Jupiter-induced gap in the protoplanetary disk that limited the inward drift of outer Solar System material at the exception of particles with size lower than 150 μm such as presolar grains. Among carbonaceous chondrites, CV chondrites show O-isotopic features suggesting potential contribution of 17-18O-rich water that may be related to their older accretion relative to other hydrated
Monitoring Butterfly Abundance: Beyond Pollard Walks
Pellet, Jérôme; Bried, Jason T.; Parietti, David; Gander, Antoine; Heer, Patrick O.; Cherix, Daniel; Arlettaz, Raphaël
2012-01-01
Most butterfly monitoring protocols rely on counts along transects (Pollard walks) to generate species abundance indices and track population trends. It is still too often ignored that a population count results from two processes: the biological process (true abundance) and the statistical process (our ability to properly quantify abundance). Because individual detectability tends to vary in space (e.g., among sites) and time (e.g., among years), it remains unclear whether index counts truly reflect population sizes and trends. This study compares capture-mark-recapture (absolute abundance) and count-index (relative abundance) monitoring methods in three species (Maculinea nausithous and Iolana iolas: Lycaenidae; Minois dryas: Satyridae) in contrasted habitat types. We demonstrate that intraspecific variability in individual detectability under standard monitoring conditions is probably the rule rather than the exception, which questions the reliability of count-based indices to estimate and compare specific population abundance. Our results suggest that the accuracy of count-based methods depends heavily on the ecology and behavior of the target species, as well as on the type of habitat in which surveys take place. Monitoring programs designed to assess the abundance and trends in butterfly populations should incorporate a measure of detectability. We discuss the relative advantages and inconveniences of current monitoring methods and analytical approaches with respect to the characteristics of the species under scrutiny and resources availability. PMID:22859980
Exo-geneology: Stellar Abundances in Solar-like Stars with Planets
NASA Astrophysics Data System (ADS)
Teske, Johanna; SDSS-IV APOGEE-2
2018-01-01
Through the process of star and planet formation, we think that the chemical abundances, or ``genes’’, of host stars are passed on to their orbiting planets. One prominent example of this is the giant planet-metallicity (iron abundance) correlation, but could other stellar ``genes’’ help explain the growing menagerie of exoplanets? Particularly interesting is the relative importance of C, O, Mg, and Si – for instance, are giant planet cores dominated by ice-forming or rock-forming elements? The ratios of these elements in terrestrial planets also control their interior structure and mineralogy, and can thus affect their similarity (or not) to Earth. In this talk I will discuss how high resolution spectroscopic studies of host stars have been and are being used to investigate how/to what extent planet properties are dependent on host star properties, focusing on solar-like (FGK) stars. I will also highlight the role that upcoming facilities can play in understanding the diversity of planets in the Galaxy.
Vyavhare, Suhas S; Way, Michael O; Medina, Raul F
2014-12-01
Stink bugs are the primary arthropod soybean pests in the southern United States. Historically, important stink bug species damaging soybeans in the southern United States included the southern green stink bug Nezara viridula (L.), the green stink bug Chinavia hilaris (Say), and the brown stink bug Euschistus servus (Say) (Hemiptera: Pentatomidae). The redbanded stink bug, Piezodorus guildinii (Westwood), has recently become an economic pest of soybean in the southern region of the United States, especially in Louisiana and Texas. Little is known about current stink bug species composition and relative abundance in Texan soybean agro-ecosystems. To fill this gap, commercial soybean fields in the Upper Gulf Coast of Texas were sampled weekly during the growing season using a sweep net throughout R2 (full flowering) to R7 (beginning maturity) from 2011 to 2013. Adults and nymphs (third, fourth, and fifth instars) of redbanded stink bug, southern green stink bug, green stink bug, and brown stink bug were counted per 25 sweeps. The relative abundance of redbanded stink bug was significantly higher than any other stink bug species throughout 2011-2013. Over 65% of the total population of major stink bugs collected during this period were redbanded stink bugs and ≍19% were southern green stink bugs. The highest redbanded stink bug densities and the highest ratio of redbanded stink bug nymphs to adults were recorded at R7. Results from this study show that redbanded stink bug has become the predominant stink bug species in soybean in the Upper Gulf Coast of Texas.
Cathryn H. Greenberg; Arlene McGrane
1996-01-01
Habitat structural characteristics and relative abundance and biomass of ground-dwelling arthropods were compared among four replicated stand treatments: intense burning and salvage logging; clearcutting followed by roller-chopping (100% soil surface disturbance): clearcutting followed by bracke seeding (30% soil surface disturbance); and naturally regenerated mature...
Optimal integrated abundances for chemical tagging of extragalactic globular clusters
NASA Astrophysics Data System (ADS)
Sakari, Charli M.; Venn, Kim; Shetrone, Matthew; Dotter, Aaron; Mackey, Dougal
2014-09-01
High-resolution integrated light (IL) spectroscopy provides detailed abundances of distant globular clusters whose stars cannot be resolved. Abundance comparisons with other systems (e.g. for chemical tagging) require understanding the systematic offsets that can occur between clusters, such as those due to uncertainties in the underlying stellar population. This paper analyses high-resolution IL spectra of the Galactic globular clusters 47 Tuc, M3, M13, NGC 7006, and M15 to (1) quantify potential systematic uncertainties in Fe, Ca, Ti, Ni, Ba, and Eu and (2) identify the most stable abundance ratios that will be useful in future analyses of unresolved targets. When stellar populations are well modelled, uncertainties are ˜0.1-0.2 dex based on sensitivities to the atmospheric parameters alone; in the worst-case scenarios, uncertainties can rise to 0.2-0.4 dex. The [Ca I/Fe I] ratio is identified as the optimal integrated [α/Fe] indicator (with offsets ≲ 0.1 dex), while [Ni I/Fe I] is also extremely stable to within ≲ 0.1 dex. The [Ba II/Eu II] ratios are also stable when the underlying populations are well modelled and may also be useful for chemical tagging.
NASA Astrophysics Data System (ADS)
Durgaprasad, N.; Yadav, J. S.; Biswas, S.
1985-08-01
A Lexan polycarbonate detector exposed on the exterior of Skylab-3 for 73 days during a solar quiet period was used to study the relative abundances of calcium to nickel ions in low energy cosmic rays of 50 to 250 MeV/N. The method of charge identification is based on the measurement of conelength (L) and residual range (R) of these particles in various Lexan sheets. Since more than one cone (sometimes as many as five) is observed and is measured, the charge accuracy becomes precise and accurate. The ratio of (calcium to manganese) to (iron and cobalt) obtained at three energy intervals of 50 to 80, 80 to 150, 150 to 250 and 50 to 250 MeV/N are 7.6 plus or minus 3.8, 2.7 plus or minus 0.8, 1.4 plus or minus 0.6 and 3.3 plus or minus 0.7 respectively. These data thus indicate a large increase of this ratio with decreasing energy. The origin of this strong energy dependence is not understood at present.
viral abundance distribution in deep waters of the Northern of South China Sea
NASA Astrophysics Data System (ADS)
He, Lei; Yin, Kedong
2017-04-01
Little is known about the vertical distribution and interaction of viruses and bacteria in the deep ocean water column. The vertical distribution of viral-like particles and bacterial abundance was investigated in the deep water column in the South China Sea during September 2005 along with salinity, temperature and dissolved oxygen. There were double maxima in the ratio of viral to bacterial abundance (VBR) in the water column: the subsurface maximum located at 50-100 m near the pycnocline layer, and the deep maximum at 800-1000 m. At the subsurface maximum of VBR, both viral and bacterial abundance were maximal in the water column, and at the deep maximum of VBR, both viral and bacterial abundance were low, but bacterial abundance was relatively lower than viral abundance. The subsurface VBR maximum coincided with the subsurface chlorophyll maximum while the deep VBR maximum coincided with the minimum in dissolved oxygen (2.91mg L-1). Therefore, we hypothesize that the two maxima were formed by different mechanisms. The subsurface VBR maximum was formed due to an increase in bacterial abundance resulting from the stimulation of abundant organic supply at the subsurface chlorophyll maximum, whereas the deep VBR maximum was formed due to a decrease in bacterial abundance caused by more limitation of organic matter at the oxygen minimum. The evidence suggests that viruses play an important role in controlling bacterial abundance in the deep water column due to the limitation of organic matter supply. In turn, this slows down the formation of the oxygen minimum in which oxygen may be otherwise lower. The mechanism has a great implication that viruses could control bacterial decomposition of organic matter, oxygen consumption and nutrient remineralization in the deep oceans.
NASA Astrophysics Data System (ADS)
Pauly, Tyler; Garrod, Robin T.
2018-02-01
Massive young stellar objects (MYSOs) in the Magellanic Clouds show infrared absorption features corresponding to significant abundances of CO, CO2, and H2O ice along the line of sight, with the relative abundances of these ices differing between the Magellanic Clouds and the Milky Way. CO ice is not detected toward sources in the Small Magellanic Cloud, and upper limits put its relative abundance well below sources in the Large Magellanic Cloud and the Milky Way. We use our gas-grain chemical code MAGICKAL, with multiple grain sizes and grain temperatures, and further expand it with a treatment for increased interstellar radiation field intensity to model the elevated dust temperatures observed in the MCs. We also adjust the elemental abundances used in the chemical models, guided by observations of H II regions in these metal-poor satellite galaxies. With a grid of models, we are able to reproduce the relative ice fractions observed in MC MYSOs, indicating that metal depletion and elevated grain temperature are important drivers of the MYSO envelope ice composition. Magellanic Cloud elemental abundances have a subgalactic C/O ratio, increasing H2O ice abundances relative to the other ices; elevated grain temperatures favor CO2 production over H2O and CO. The observed shortfall in CO in the Small Magellanic Cloud can be explained by a combination of reduced carbon abundance and increased grain temperatures. The models indicate that a large variation in radiation field strength is required to match the range of observed LMC abundances. CH3OH abundance is found to be enhanced in low-metallicity models, providing seed material for complex organic molecule formation in the Magellanic Clouds.
Heavy-Element Abundances in Blue Compact Galaxies
NASA Astrophysics Data System (ADS)
Izotov, Yuri I.; Thuan, Trinh X.
1999-02-01
We present high-quality ground-based spectroscopic observations of 54 supergiant H II regions in 50 low-metallicity blue compact galaxies with oxygen abundances 12+logO/H between 7.1 and 8.3. We use the data to determine abundances for the elements N, O, Ne, S, Ar, and Fe. We also analyze Hubble Space Telescope (HST) Faint Object Spectrograph archival spectra of 10 supergiant H II regions to derive C and Si abundances in a subsample of seven BCGs. The main result of the present study is that none of the heavy element-to-oxygen abundance ratios studied here (C/O, N/O, Ne/O, Si/O, S/O, Ar/O, Fe/O) depend on oxygen abundance for BCGs with 12+logO/H<=7.6 (Z<=Zsolar/20). This constancy implies that all of these heavy elements have a primary origin and are produced by the same massive (M>=10 Msolar) stars responsible for O production. The dispersion of the ratios C/O and N/O in these galaxies is found to be remarkably small, being only +/-0.03 and +/-0.02 dex, respectively. This very small dispersion is strong evidence against any time-delayed production of C and primary N in the lowest metallicity BCGs (secondary N production is negligible at these low metallicities). The absence of a time-delayed production of C and N is consistent with the scenario that galaxies with 12+logO/H<=7.6 are now undergoing their first burst of star formation, and that they are therefore young, with ages not exceeding 40 Myr. If very low metallicity BCGs are indeed young, this would argue against the commonly held belief that C and N are produced by intermediate-mass (3 Msolar<=M<=9 Msolar) stars at very low metallicities, as these stars would not have yet completed their evolution in these lowest metallicity galaxies. In higher metallicity BCGs (7.6<12+logO/H<8.2), the abundance ratios Ne/O, Si/O, S/O, Ar/O, and Fe/O retain the same constant value they had at lower metallicities. By contrast, there is an increase of C/O and N/O along with their dispersions at a given O. We interpret this
Relative abundance of heavy ions in the inner zone of the radiation belts of the earth
DOE Office of Scientific and Technical Information (OSTI.GOV)
Panasyuk, M.I.
1986-03-01
The energy dependences of the relative abundances of energetic (E > 1 MeV/nucleon) H, He, and O ions in the radiation belts are analyzed on the basis of experimental results obtained from measurement of their spectral characteristics on several satellites: Molniya-2, Kosmos-900, Prognoz-5, Explorer-45, ISEE-1, and OV1-19. It is shown that the formation of the energy dependence of He/H and O/H can be explained with a model providing for ion diffusion into the interior of the radiation belts with Coulomb losses taken into account under thecondition that the total-energy spectra at the boundary are more rigid for the heavy ionsmore » and are determined by such parameters of the quiet solar wind as the relative concentrations of the individual ion components and their charge states. It is shown that the fluxes of O and Fe ions with E > 1 MeV/nucleon measured on the orbital stations Salyut-6 and Skylab have an energy dependence of the relative abundances not inconsistent with above-noted mechanism for the formation of energetic ions of the inner radiation belt.« less
Yeatman, Georgina J; Wayne, Adrian F; Mills, Harriet R; Prince, Jane
2016-01-01
The aim of this study was to investigate how landscape disturbance associated with roads, agriculture and forestry influenced temporal patterns in woylie (Bettongia penicillata) abundance before, during and after periods of rapid population change. Data were collected from an area of approximately 140,000 ha of forest within the Upper Warren region in south-western Australia. Woylie abundance was measured using cage trapping at 22 grid and five transect locations with varying degrees of landscape disturbance between 1994 and 2012. We found evidence that the distribution and abundance of woylies over time appears to be related to the degree of fragmentation by roads and proximity to agriculture. Sites furthest from agriculture supported a greater abundance of woylies and had slower rates of population decline. Sites with fewer roads had a greater abundance of woylies generally and a greater rate of increase in abundance after the implementation of invasive predator control. The results of this study suggest that landscape disturbance is less important at peak population densities, but during times of environmental and population change, sites less dissected by roads and agriculture better support woylie populations. This may be due to the role these factors play in increasing the vulnerability of woylies to introduced predators, population fragmentation, weed species invasion, mortality from road collisions or a reduction in available habitat. Strategies that reduce the impact of disturbance on woylie populations could include the rationalisation of forest tracks and consolidation of contiguous habitat through the acquisition of private property. Reducing the impact of disturbance in the Upper Warren region could improve the resilience of this critically important woylie population during future environmental change.
Yeatman, Georgina J.; Wayne, Adrian F.; Mills, Harriet R.; Prince, Jane
2016-01-01
The aim of this study was to investigate how landscape disturbance associated with roads, agriculture and forestry influenced temporal patterns in woylie (Bettongia penicillata) abundance before, during and after periods of rapid population change. Data were collected from an area of approximately 140,000 ha of forest within the Upper Warren region in south-western Australia. Woylie abundance was measured using cage trapping at 22 grid and five transect locations with varying degrees of landscape disturbance between 1994 and 2012. We found evidence that the distribution and abundance of woylies over time appears to be related to the degree of fragmentation by roads and proximity to agriculture. Sites furthest from agriculture supported a greater abundance of woylies and had slower rates of population decline. Sites with fewer roads had a greater abundance of woylies generally and a greater rate of increase in abundance after the implementation of invasive predator control. The results of this study suggest that landscape disturbance is less important at peak population densities, but during times of environmental and population change, sites less dissected by roads and agriculture better support woylie populations. This may be due to the role these factors play in increasing the vulnerability of woylies to introduced predators, population fragmentation, weed species invasion, mortality from road collisions or a reduction in available habitat. Strategies that reduce the impact of disturbance on woylie populations could include the rationalisation of forest tracks and consolidation of contiguous habitat through the acquisition of private property. Reducing the impact of disturbance in the Upper Warren region could improve the resilience of this critically important woylie population during future environmental change. PMID:27501320
Deciphering the Measured Ratios of Iodine-131 to Cesium-137 at the Fukushima Reactors
NASA Astrophysics Data System (ADS)
Matsui, T.
2011-12-01
We calculate the relative abundance of the radioactive isotopes Iodine-131 and Cesium-137 produced by nuclear fission in reactors and compare it with data taken at the troubled Fukushima Dai-ichi nuclear power plant. The ratio of radioactivities of these two isotopes can be used to obtain information about when the nuclear reactions terminated.
NASA Astrophysics Data System (ADS)
Colucci, Janet E.; Bernstein, Rebecca A.; Cameron, Scott A.; McWilliam, Andrew
2012-02-01
We present detailed chemical abundances in eight clusters in the Large Magellanic Cloud (LMC). We measure abundances of 22 elements for clusters spanning a range in age of 0.05-12 Gyr, providing a comprehensive picture of the chemical enrichment and star formation history of the LMC. The abundances were obtained from individual absorption lines using a new method for analysis of high-resolution (R ~ 25,000), integrated-light (IL) spectra of star clusters. This method was developed and presented in Papers I, II, and III of this series. In this paper, we develop an additional IL χ2-minimization spectral synthesis technique to facilitate measurement of weak (~15 mÅ) spectral lines and abundances in low signal-to-noise ratio data (S/N ~ 30). Additionally, we supplement the IL abundance measurements with detailed abundances that we measure for individual stars in the youngest clusters (age < 2 Gyr) in our sample. In both the IL and stellar abundances we find evolution of [α/Fe] with [Fe/H] and age. Fe-peak abundance ratios are similar to those in the Milky Way (MW), with the exception of [Cu/Fe] and [Mn/Fe], which are sub-solar at high metallicities. The heavy elements Ba, La, Nd, Sm, and Eu are significantly enhanced in the youngest clusters. Also, the heavy to light s-process ratio is elevated relative to the MW ([Ba/Y] >+0.5) and increases with decreasing age, indicating a strong contribution of low-metallicity asymptotic giant branch star ejecta to the interstellar medium throughout the later history of the LMC. We also find a correlation of IL Na and Al abundances with cluster mass in the sense that more massive, older clusters are enriched in the light elements Na and Al with respect to Fe, which implies that these clusters harbor star-to-star abundance variations as is common in the MW. Lower mass, intermediate-age, and young clusters have Na and Al abundances that are lower and more consistent with LMC field stars. Our results can be used to constrain both
NASA Astrophysics Data System (ADS)
Shafer, J. T.; Neal, C. R.
2003-12-01
Picritic and high-MgO (7.7-24 wt.%) basalt samples from Detroit (/sim81-76 Ma) and Koko (/sim48 Ma) Seamounts along the ESC have been analyzed for PGEs (Ru, Rh, Pd, Ir, and Pt) allowing an examination of how the PGEs in lavas from the Hawaiian plume have changed over time. Major and trace element (including the PGEs) concentrations were quantified by ICP methods at the University of Notre Dame. See Ely et al. (1999, Chem. Geol. 157:219) for the PGE analytical method. Bennett et al. (2000) analyzed Hawaiian picrites and found PGE abundances slightly greater than average MORB and comparable to the low-PGE basaltic komatiites. These authors modeled the PGE abundances of these picrites by using variable amounts of residual sulfide during melting, such that Koolau (low PGE contents) formed from a relatively sulfide-rich source and Loihi (high PGEs) from a sulfide-poor source. Our PGE data from Detroit Seamount show slightly higher PGE abundances than Loihi and Kilauea, suggesting these picrites formed from a source lacking residual sulfide. These results suggest that, if the model of Bennett et al. (2000) is correct, the dilution of plume lava with MORB source, as hypothesized on the basis of depleted isotope ratios and lower trace element abundances than modern Hawaii (Keller et al., 2000, Nature 405:603; Kinman & Neal, 2002, Eos 83:F1282; Regelous et al., 2003, JPet 44:113), was not the controlling factor in PGE abundances. However, since MORB PGE concentrations are not substantially different than low-PGE Hawaiian picrites, incorporation of MORB material within the Hawaiian plume at Detroit Seamount would not have drastically reduced the PGE abundances. Koko Seamount has relatively high PGE concentrations (/sim3-12 times greater than those from Detroit lavas). This may be the result of a lack of residual sulfide facilitated by higher degrees of partial melting. Although our initial data are consistent with variable degrees of partial melting and/or source
Abundances of Local Group Globular Clusters Using High Resolution Integrated Light Spectroscopy
NASA Astrophysics Data System (ADS)
Sakari, Charli; McWilliam, A.; Venn, K.; Shetrone, M. D.; Dotter, A. L.; Mackey, D.
2014-01-01
Abundances and kinematics of extragalactic globular clusters provide valuable clues about galaxy and globular cluster formation in a wide variety of environments. In order to obtain such information about distant, unresolved systems, specific observational techniques are required. An Integrated Light Spectrum (ILS) provides a single spectrum from an entire stellar population, and can therefore be used to determine integrated cluster abundances. This dissertation investigates the accuracy of high resolution ILS analysis methods, using ILS (taken with the Hobby-Eberly Telescope) of globular clusters associated with the Milky Way (47 Tuc, M3, M13, NGC 7006, and M15) and then applies the method to globular clusters in the outer halo of M31 (from the Pan-Andromeda Archaeological Survey, or PAndAS). Results show that: a) as expected, the high resolution method reproduces individual stellar abundances for elements that do not vary within a cluster; b) the presence of multiple populations does affect the abundances of elements that vary within the cluster; c) certain abundance ratios are very sensitive to systematic effects, while others are not; and d) certain abundance ratios (e.g. [Ca/Fe]) can be accurately obtained from unresolved systems. Applications of ILABUNDS to the PAndAS clusters reveal that accretion may have played an important role in the formation of M31's outer halo.
Carbon and nitrogen abundances in F- and G-type stars
NASA Technical Reports Server (NTRS)
Clegg, R. E. S.
1977-01-01
Carbon and nitrogen abundances have been obtained for a sample of 11-F- and G-type dwarfs covering a range in Fe/H abundance ratio from -0.8 to +0.3. Model atmospheres, which included the effects of convection and line blanketing, were used to calculate synthetic spectra of the CH, CN, and NH molecular bands. Effective oscillator strengths for the bands studied were found by matching synthetic spectra calculated from a model solar atmosphere with the observed solar bands. Many of the metal-poor stars, and particularly the high-velocity stars, were found to have substantial nitrogen over-deficiencies, suggesting that N is manufactured mostly in a secondary manner. The carbon-to-iron ratios were similar to the solar ratio, although there may be slight C over-deficiencies in metal-poor stars. However, the variation in C/Fe is not as marked as that found recently by Hearnshaw (1974). A comprehensive discussion of the theoretical errors is given, and some applications to Galactic evolution are noted.
The abundances of the elements in sharp-lined early type stars
NASA Technical Reports Server (NTRS)
Adelman, Saul J.
1992-01-01
An International Ultraviolet Explorer (IUE) observing strategy that has yielded co-added spectra with enhanced S/N ratios for several A and B stars was established. New observations by Roby and Adelman using the same technique were added two new Hg-Mn stars into this sample. A long-term study of elemental abundances in this uniform, high-quality set of IUE spectra for 13 stars was begun. The first stages of this project are reported: abundances for N, Cr, Mn, Fe, Co, and Ni. The study of the Fe-peak elements show that our data set can provide accurate abundances and that abundances obtained from UV and optical spectra often are in good agreement. The groundwork for selfconsistent abundance analyses of more exotic elements in our long term project was provided.
ON THE OXYGEN AND NITROGEN CHEMICAL ABUNDANCES AND THE EVOLUTION OF THE 'GREEN PEA' GALAXIES
DOE Office of Scientific and Technical Information (OSTI.GOV)
Amorin, Ricardo O.; Perez-Montero, Enrique; Vilchez, J. M., E-mail: amorin@iaa.e, E-mail: epm@iaa.e, E-mail: jvm@iaa.e
2010-06-01
We have investigated the oxygen and nitrogen chemical abundances in extremely compact star-forming galaxies (SFGs) with redshifts between {approx}0.11 and 0.35, popularly referred to as 'green peas'. Direct and strong-line methods sensitive to the N/O ratio applied to their Sloan Digital Sky Survey (SDSS) spectra reveal that these systems are genuine metal-poor galaxies, with mean oxygen abundances {approx}20% solar. At a given metallicity these galaxies display systematically large N/O ratios compared to normal galaxies, which can explain the strong difference between our metallicities measurements and previous ones. While their N/O ratios follow the relation with stellar mass of local SFGsmore » in the SDSS, we find that the mass-metallicity relation of the 'green peas' is offset {approx_gt}0.3 dex to lower metallicities. We argue that recent interaction-induced inflow of gas, possibly coupled with a selective metal-rich gas loss, driven by supernova winds, may explain our findings and the known galaxy properties, namely high specific star formation rates, extreme compactness, and disturbed optical morphologies. The 'green pea' galaxy properties seem to be uncommon in the nearby universe, suggesting a short and extreme stage of their evolution. Therefore, these galaxies may allow us to study in great detail many processes, such as starburst activity and chemical enrichment, under physical conditions approaching those in galaxies at higher redshifts.« less
Egge, Elianne; Bittner, Lucie; Andersen, Tom; Audic, Stéphane; de Vargas, Colomban; Edvardsen, Bente
2013-01-01
Next generation sequencing of ribosomal DNA is increasingly used to assess the diversity and structure of microbial communities. Here we test the ability of 454 pyrosequencing to detect the number of species present, and assess the relative abundance in terms of cell numbers and biomass of protists in the phylum Haptophyta. We used a mock community consisting of equal number of cells of 11 haptophyte species and compared targeting DNA and RNA/cDNA, and two different V4 SSU rDNA haptophyte-biased primer pairs. Further, we tested four different bioinformatic filtering methods to reduce errors in the resulting sequence dataset. With sequencing depth of 11000–20000 reads and targeting cDNA with Haptophyta specific primers Hap454 we detected all 11 species. A rarefaction analysis of expected number of species recovered as a function of sampling depth suggested that minimum 1400 reads were required here to recover all species in the mock community. Relative read abundance did not correlate to relative cell numbers. Although the species represented with the largest biomass was also proportionally most abundant among the reads, there was generally a weak correlation between proportional read abundance and proportional biomass of the different species, both with DNA and cDNA as template. The 454 sequencing generated considerable spurious diversity, and more with cDNA than DNA as template. With initial filtering based only on match with barcode and primer we observed 100-fold more operational taxonomic units (OTUs) at 99% similarity than the number of species present in the mock community. Filtering based on quality scores, or denoising with PyroNoise resulted in ten times more OTU99% than the number of species. Denoising with AmpliconNoise reduced the number of OTU99% to match the number of species present in the mock community. Based on our analyses, we propose a strategy to more accurately depict haptophyte diversity using 454 pyrosequencing. PMID:24069303
Temporal patterns in capture rate and sex ratio of forest bats in Arkansas
Roger W. Perry; S. Andrew Carter; Ronald E. Thill
2010-01-01
We quantified changes in capture rates and sex ratios from May to Sept. for eight species of bats, derived from 8 y of extensive mist netting in forests of the Ouachita Mountains, Arkansas. Our primary goal was to determine patterns of relative abundance for each species of bat captured over forest streams and to determine if these patterns were similar to patterns of...
Determining the Stellar Initial Mass by Means of the 17O/18O Ratio on the AGB
NASA Astrophysics Data System (ADS)
De Nutte, Rutger; Decin, Leen; Olofsson, Hans; de Koter, Alex; Karakas, Amanda; Lombaert, Robin; Milam, Stefanie; Ramstedt, Sofia; Stancliffe, Richard; Homan, Ward; Van de Sande, Marie
2016-07-01
This poster presentsnewly obtainedcircumstellar 12C17O and 12C18O line observations, from which theline intensity are then related directly tothe 17O/18O surface abundance ratiofor a sample of nine AGB stars covering the three spectral types ().These ratios are evaluated in relation to a fundamental stellar evolution parameters: the stellar initial mass. The17O/18O ratio is shown to function as an effective method of determining the initial stellar mass. Through comparison with predictions bystellar evolution models, accurate initial mass estimates are calculated for all nine sources.
A predictive relationship between population and genetic sex ratios in clonal species
NASA Astrophysics Data System (ADS)
McLetchie, D. Nicholas; García-Ramos, Gisela
2017-04-01
Sexual reproduction depends on mate availability that is reflected by local sex ratios. In species where both sexes can clonally expand, the population sex ratio describes the proportion of males, including clonally derived individuals (ramets) in addition to sexually produced individuals (genets). In contrast to population sex ratio that accounts for the overall abundance of the sexes, the genetic sex ratio reflects the relative abundance of genetically unique mates, which is critical in predicting effective population size but is difficult to estimate in the field. While an intuitive positive relationship between population (ramet) sex ratio and genetic (genet) sex ratio is expected, an explicit relationship is unknown. In this study, we determined a mathematical expression in the form of a hyperbola that encompasses a linear to a nonlinear positive relationship between ramet and genet sex ratios. As expected when both sexes clonally have equal number of ramets per genet both sex ratios are identical, and thus ramet sex ratio becomes a linear function of genet sex ratio. Conversely, if sex differences in ramet number occur, this mathematical relationship becomes nonlinear and a discrepancy between the sex ratios amplifies from extreme sex ratios values towards intermediate values. We evaluated our predictions with empirical data that simultaneously quantified ramet and genet sex ratios in populations of several species. We found that the data support the predicted positive nonlinear relationship, indicating sex differences in ramet number across populations. However, some data may also fit the null model, which suggests that sex differences in ramet number were not extensive, or the number of populations was too small to capture the curvature of the nonlinear relationship. Data with lack of fit suggest the presence of factors capable of weakening the positive relationship between the sex ratios. Advantages of this model include predicting genet sex ratio using
Rudney, Joel D; Jagtap, Pratik D; Reilly, Cavan S; Chen, Ruoqiong; Markowski, Todd W; Higgins, LeeAnn; Johnson, James E; Griffin, Timothy J
2015-12-19
The etiology of dental caries is multifactorial, but frequent consumption of free sugars, notably sucrose, appears to be a major factor driving the supragingival microbiota in the direction of dysbiosis. Recent 16S rRNA-based studies indicated that caries-associated communities were less diverse than healthy supragingival plaque but still displayed considerable taxonomic diversity between individuals. Metagenomic studies likewise have found that healthy oral sites from different people were broadly similar with respect to gene function, even though there was an extensive individual variation in their taxonomic profiles. That pattern may also extend to dysbiotic communities. In that case, shifts in community-wide protein relative abundance might provide better biomarkers of dysbiosis that can be achieved through taxonomy alone. In this study, we used a paired oral microcosm biofilm model of dental caries to investigate differences in community composition and protein relative abundance in the presence and absence of sucrose. This approach provided large quantities of protein, which facilitated deep metaproteomic analysis. Community composition was evaluated using 16S rRNA sequencing and metaproteomic approaches. Although taxonomic diversity was reduced by sucrose pulsing, considerable inter-subject variation in community composition remained. By contrast, functional analysis using the SEED ontology found that sucrose induced changes in protein relative abundance patterns for pathways involving glycolysis, lactate production, aciduricity, and ammonia/glutamate metabolism that were conserved across taxonomically diverse dysbiotic oral microcosm biofilm communities. Our findings support the concept of using function-based changes in protein relative abundance as indicators of dysbiosis. Our microcosm model cannot replicate all aspects of the oral environment, but the deep level of metaproteomic analysis it allows makes it suitable for discovering which proteins are
Brewer, S.K.; Rabeni, C.F.; Sowa, S.P.; Annis, G.
2007-01-01
Protecting and restoring fish populations on a regional basis are most effective if the multiscale factors responsible for the relative quality of a fishery are known. We spatially linked Missouri's statewide historical fish collections to environmental features in a geographic information system, which was used as a basis for modeling the importance of landscape and stream segment features in supporting a population of smallmouth bass Micropterus dolomieu. Decision tree analyses were used to develop probability-based models to predict statewide occurrence and within-range relative abundances. We were able to identify the range of smallmouth bass throughout Missouri and the probability of occurrence within that range by using a few broad landscape variables: the percentage of coarse-textured soils in the watershed, watershed relief, and the percentage of soils with low permeability in the watershed. The within-range relative abundance model included both landscape and stream segment variables. As with the statewide probability of occurrence model, soil permeability was particularly significant. The predicted relative abundance of smallmouth bass in stream segments containing low percentages of permeable soils was further influenced by channel gradient, stream size, spring-flow volume, and local slope. Assessment of model accuracy with an independent data set showed good concordance. A conceptual framework involving naturally occurring factors that affect smallmouth bass potential is presented as a comparative model for assessing transferability to other geographic areas and for studying potential land use and biotic effects. We also identify the benefits, caveats, and data requirements necessary to improve predictions and promote ecological understanding. ?? Copyright by the American Fisheries Society 2007.
Cosmological and astrophysical consequences of a high primordial deuterium abundance
NASA Astrophysics Data System (ADS)
Vangioni-Flam, Elisabeth; Casse, Michel
1995-03-01
We explore the consequences of the first detection of deuterium in a high-redshift, very metal-poor absorbing cloud complex, D/H = (1.9-2.5) x 10-4, by Songaila et al. and Carswell et al., obtained with the Keck telescope. This value reflects closely the primordial abundance ratio provided that the observed spectral features are not due to the corruption of the signal by an errant hydrogen cloud of misfortunate velocity. Assuming that the measured D abundance is free from contamination, the baryon/photon ratio is now confined to the range 1.3-2 (instead of 3-4 and more), in both the classical and inhomogeneous big bangs. Other light elements (He-3, He-4 and Li-7) are consistent with these figures. The low baryonic density of the universe that ensues leaves no room for baryonic matter in the extended halos of elliptical galaxies, especially if the Hubble parameter is close to 100 km/s/Mpc. Nonbaryonic matter clearly dominates the gravitating mass of clusters of galaxies. The upper limit of the gas density at high redshift (before bulk galaxy formation) is now consistent with the baryonic one. A massive destruction of deuterium, in the course of the evolution of the galaxy (say, by a factor of 10-25) is required to match the D/H ratio observed in the local interstellar medium. The higher D destruction proposed up to now corresponds to galactic evolutionary models devised by Vangioni-Flam & Audouze (1988) and Vangioni-Flam, Olive, & Prantzos (1994). We discuss the virtues and the limits of this class of models and propose an alternative based on mass related to a galactic wind.
Ferro, C; Morrison, A C; Torres, M; Pardo, R; Wilson, M L; Tesh, R B
1995-07-01
Ecological studies on the sand fly Lutzomyia longipalpis (Lutz & Neiva) were conducted during 1990-1993 at a small rural community in Colombia where American visceral leishmaniasis is endemic. Weekly sand fly collections were made from pigpens, houses, and natural resting sites, using hand-held aspirators, sticky (oiled) paper traps, and opossum-baited Disney traps. In total, 263,094 sand flies were collected; L. longipalpis predominated (86.1%), followed by L. trinidadensis (11.0%), L. cayennensis (2.7%), and 8 other Lutzomyia species. The species composition and sex ratio of these sand flies varied among sites and by collection method. L. longipalpis were captured most efficiently by direct aspiration from animal bait. Conversely, sticky paper traps, especially inside houses and at rock resting sites, collected a greater diversity of species, but a lower relative abundance of L. longipalpis.
Bi-Abundance Ionisation Structure of the Wolf-Rayet Planetary Nebula PB 8
NASA Astrophysics Data System (ADS)
Danehkar, A.
2018-01-01
The planetary nebula PB 8 around a [WN/WC]-hybrid central star is one of planetary nebulae with moderate abundance discrepancy factors (ADFs 2-3), which could be an indication of a tiny fraction of metal-rich inclusions embedded in the nebula (bi-abundance). In this work, we have constructed photoionisation models to reproduce the optical and infrared observations of the planetary nebula PB 8 using a non-LTE stellar model atmosphere ionising source. A chemically homogeneous model initially used cannot predict the optical recombination lines. However, a bi-abundance model provides a better fit to most of the observed optical recombination lines from N and O ions. The metal-rich inclusions in the bi-abundance model occupy 5.6% of the total volume of the nebula, and are roughly 1.7 times cooler and denser than the mean values of the surrounding nebula. The N/H and O/H abundance ratios in the metal-rich inclusions are 1.0 and 1.7 dex larger than the diffuse warm nebula, respectively. To reproduce the Spitzer spectral energy distribution of PB 8, dust grains with a dust-to-gas ratio of 0.01 (by mass) were also included. It is found that the presence of metal-rich inclusions can explain the heavy element optical recombination lines, while a dual-dust chemistry with different grain species and discrete grain sizes likely produces the infrared continuum of this planetary nebula. This study demonstrates that the bi-abundance hypothesis, which was examined in a few planetary nebulae with large abundance discrepancies (ADFs > 10), could also be applied to those typical planetary nebulae with moderate abundance discrepancies.
Monthly analysis of PM ratio characteristics and its relation to AOD.
Sorek-Hamer, Meytar; Broday, David M; Chatfield, Robert; Esswein, Robert; Stafoggia, Massimo; Lepeule, Johanna; Lyapustin, Alexei; Kloog, Itai
2017-01-01
Airborne particulate matter (PM) is derived from diverse sources-natural and anthropogenic. Climate change processes and remote sensing measurements are affected by the PM properties, which are often lumped into homogeneous size fractions that show spatiotemporal variation. Since different sources are attributed to different geographic locations and show specific spatial and temporal PM patterns, we explored the spatiotemporal characteristics of the PM 2.5 /PM 10 ratio in different areas. Furthermore, we examined the statistical relationships between AERONET aerosol optical depth (AOD) products, satellite-based AOD, and the PM ratio, as well as the specific PM size fractions. PM data from the northeastern United States, from San Joaquin Valley, CA, and from Italy, Israel, and France were analyzed, as well as the spatial and temporal co-measured AOD products obtained from the MultiAngle Implementation of Atmospheric Correction (MAIAC) algorithm. Our results suggest that when both the AERONET AOD and the AERONET fine-mode AOD are available, the AERONET AOD ratio can be a fair proxy for the ground PM ratio. Therefore, we recommend incorporating the fine-mode AERONET AOD in the calibration of MAIAC. Along with a relatively large variation in the observed PM ratio (especially in the northeastern United States), this shows the need to revisit MAIAC assumptions on aerosol microphysical properties, and perhaps their seasonal variability, which are used to generate the look-up tables and conduct aerosol retrievals. Our results call for further scrutiny of satellite-borne AOD, in particular its errors, limitations, and relation to the vertical aerosol profile and the particle size, shape, and composition distribution. This work is one step of the required analyses to gain better understanding of what the satellite-based AOD represents. The analysis results recommend incorporating the fine-mode AERONET AOD in MAIAC calibration. Specifically, they indicate the need to revisit
Financial development and oil resource abundance-growth relations: evidence from panel data.
Law, Siong Hook; Moradbeigi, Maryam
2017-10-01
This study investigates whether financial development dampens the negative impact of oil resource abundance on economic growth. Because of substantial cross-sectional dependence in our data, which contain a core sample of 63 oil-producing countries from 1980 through 2010, we use the common correlated effect mean group (CCEMG) estimator to account for the high degree of heterogeneity and drop the outlier countries. The empirical results reveal that oil resource abundance affects the growth rate in output contingent on the degree of development in financial markets. More developed financial markets can channel the revenues from oil into more productive activities and thus offset the negative effects of oil resource abundance on economic growth. Thus, better financial development can reverse resource curse or enhance resource blessing in oil-rich economies.
NASA Astrophysics Data System (ADS)
Vukajlovich, D. J.; Hilton, D. R.; Castillo, P. R.; Hawkins, J. W.
2005-12-01
The Lau Basin has multiple mantle source components including contributions from the Indian and Pacific MORB sources, Tonga-Kermadec Arc and Samoan plume. In order to characterize the volatile systematics of these various sources and to map their spatial distribution, we have sampled basaltic glasses from over 50 dredge sites covering all known spreading centers in the basin as well as many off-axis seamounts. Here, we report He abundance and isotope results obtained by crushing, in addition to CO2 released through stepped heating, from sites at the Mangatolu Triple Junction (MTJ), Rochambeau Bank (RB), Peggy Ridge, and the Northern, Eastern and Central Lau Spreading Centers. High 3He/4He ratios from RB (up to 23 RA, where RA = air 3He/4He) confirm the presence of a plume component in the northwestern Lau Basin (Poreda, EPSL, 1985). Central and Eastern Lau Spreading Center basalts have 3He/4He ratios between 8.3 and 9.4 RA, consistent with a depleted, MORB-like mantle source with little influence from slab or crustal helium. In contrast, the large range in helium isotope ratios of MTJ samples (0.85 to 7.9 RA) and the correlation between low He abundances (~2 - 3 × 10-9 cm3/g) and low helium isotope ratios suggests the volatiles in this region have been severely affected by degassing and additions of radiogenic (crustal) He. CO2 abundances and carbon isotopes for samples from RB vary from 70 to 119 ppm ([CO2]total) with δ13Cvesicle falling between -12.3 to -14.8 ‰ and δ13Cdissolved lying between -9.3 to -10.7 ‰. In the MTJ, low helium concentration samples have δ13C as low as -27.4 ‰ and [CO2]total as low as 7.6ppm; interestingly, this region also has samples with the highest measured values (up to -6.3 ‰ and 132ppm total C). Combining the carbon and helium data, CO2/3He ratios in the MTJ range from arc-like values (~1010) to sediment or crustal values (~1013) showing the superimposition of degassing and/or contamination effects on a predominant slab
NASA Astrophysics Data System (ADS)
Kawakita, Hideyo; Shinnaka, Yoshiharu; Jehin, Emmanuel; Decock, Alice; Hutsemekers, Damien; Manfroid, Jean
2016-10-01
Since molecules having identical protons can be classified into nuclear-spin isomers (e.g., ortho-H2O and para-H2O for water) and their inter-conversions by radiative and non-destructive collisional processes are believed to be very slow, the ortho-to-para abundance ratios (OPRs) of cometary volatiles such as H2O, NH3 and CH4 in coma have been considered as primordial characters of cometary molecules [1]. Those ratios are usually interpreted as nuclear-spin temperatures although the real meaning of OPRs is in strong debate. Recent progress in laboratory studies about nuclear-spin conversion in gas- and solid-phases [2,3] revealed short-time nuclear-spin conversions for water, and we have to reconsider the interpretation for observed OPRs of cometary volatiles. We have already performed the survey for OPRs of NH2 in more than 20 comets by large aperture telescopes with high-resolution spectrographs (UVES/VLT, HDS/Subaru, etc.) in the optical wavelength region [4]. The observed OPRs of ammonia estimated from OPRs of NH2, cluster around ~1.1 (cf. 1.0 as a high-temperature limit), indicative of ~30 K as nuclear-spin temperatures. We present our latest results for OPRs of cometary NH2 and discuss about the real meaning of OPRs of cometary ammonia, in relation to OPRs of water in cometary coma. Chemical processes in the inner coma may play an important role to achieve un-equilibrated OPRs of cometary volatiles in coma.This work was financially supported by MEXT Supported Program for the Strategic Research Foundation at Private Universities, 2014-2018 (No. S1411028) (HK) and by Graint-in-Aid for JSPS Fellows, 15J10864 (YS).References:[1] Mumma & Charnley, 2011, Annu. Rev. Astro. Astrophys. 49, 471.[2] Hama & Watanabe, 2013, Chem. Rev. 113, 8783.[3] Hama et al., 2008, Science 351, 6268.[4] Shinnaka et al., 2011, ApJ 729, 81.
The HNC/HCN ratio in star-forming regions
DOE Office of Scientific and Technical Information (OSTI.GOV)
Graninger, Dawn M.; Öberg, Karin I.; Herbst, Eric
2014-05-20
HNC and HCN, typically used as dense gas tracers in molecular clouds, are a pair of isomers that have great potential as a temperature probe because of temperature dependent, isomer-specific formation and destruction pathways. Previous observations of the HNC/HCN abundance ratio show that the ratio decreases with increasing temperature, something that standard astrochemical models cannot reproduce. We have undertaken a detailed parameter study on which environmental characteristics and chemical reactions affect the HNC/HCN ratio and can thus contribute to the observed dependence. Using existing gas and gas-grain models updated with new reactions and reaction barriers, we find that in staticmore » models the H + HNC gas-phase reaction regulates the HNC/HCN ratio under all conditions, except for very early times. We quantitatively constrain the combinations of H abundance and H + HNC reaction barrier that can explain the observed HNC/HCN temperature dependence and discuss the implications in light of new quantum chemical calculations. In warm-up models, gas-grain chemistry contributes significantly to the predicted HNC/HCN ratio and understanding the dynamics of star formation is therefore key to model the HNC/HCN system.« less
The dependence of oxygen and nitrogen abundances on stellar mass from the CALIFA survey
NASA Astrophysics Data System (ADS)
Pérez-Montero, E.; García-Benito, R.; Vílchez, J. M.; Sánchez, S. F.; Kehrig, C.; Husemann, B.; Duarte Puertas, S.; Iglesias-Páramo, J.; Galbany, L.; Mollá, M.; Walcher, C. J.; Ascasíbar, Y.; González Delgado, R. M.; Marino, R. A.; Masegosa, J.; Pérez, E.; Rosales-Ortega, F. F.; Sánchez-Blázquez, P.; Bland-Hawthorn, J.; Bomans, D.; López-Sánchez, Á. R.; Ziegler, B.; Califa Collaboration
2016-10-01
Context. The study of the integrated properties of star-forming galaxies is central to understand their formation and evolution. Some of these properties are extensive and therefore their analysis require totally covering and spatially resolved observations. Among these properties, metallicity can be defined in spiral discs by means of integral field spectroscopy (IFS) of individual H II regions. The simultaneous analysis of the abundances of primary elements, as oxygen, and secondary, as nitrogen, also provides clues about the star formation history and the processes that shape the build-up of spiral discs. Aims: Our main aim is to analyse simultaneously O/H and N/O abundance ratios in H II regions in different radial positions of the discs in a large sample of spiral galaxies to obtain the slopes and the characteristic abundance ratios that can be related to their integrated properties. Methods: We analysed the optical spectra of individual selected H II regions extracted from a sample of 350 spiral galaxies of the CALIFA survey. We calculated total O/H abundances and, for the first time, N/O ratios using the semi-empirical routine Hii-Chi-mistry, which, according to Pérez-Montero (2014, MNRAS, 441, 2663), is consistent with the direct method and reduces the uncertainty in the O/H derivation using [N II] lines owing to the dispersion in the O/H-N/O relation. Then we performed linear fittings to the abundances as a function of the de-projected galactocentric distances. Results: The analysis of the radial distribution both for O/H and N/O in the non-interacting galaxies reveals that both average slopes are negative, but a non-negligible fraction of objects have a flat or even a positive gradient (at least 10% for O/H and 4% for N/O). The slopes normalised to the effective radius appear to have a slight dependence on the total stellar mass and the morphological type, as late low-mass objects tend to have flatter slopes. No clear relation is found, however, to
Validity of abundances derived from spaxel spectra of the MaNGA survey
NASA Astrophysics Data System (ADS)
Pilyugin, L. S.; Grebel, E. K.; Zinchenko, I. A.; Nefedyev, Y. A.; Shulga, V. M.; Wei, H.; Berczik, P. P.
2018-05-01
We measured the emission lines in the spaxel spectra of Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) galaxies in order to determine the abundance distributions therein. It has been suggested that the strength of the low-ionization lines, R2, N2, and S2, may be increased (relative to Balmer lines) in (some) spaxel spectra of the MaNGA survey due to a contribution of the radiation of the diffuse ionized gas. Consequently, the abundances derived from the spaxel spectra through strong-line methods may suffer from large errors. We examined this expectation by comparing the behaviour of the line intensities and the abundances estimated through different calibrations for slit spectra of H II regions in nearby galaxies, for fibre spectra from the Sloan Digital Sky Survey, and for spaxel spectra of the MaNGA survey. We found that the S2 strength is increased significantly in the fibre and spaxel spectra. The mean enhancement changes with metallicity and can be as large as a factor of 2. The mean distortion of R2 and N2 is less than a factor of 1.3. This suggests that Kaufmann et al.'s (2003, MNRAS, 346, 1055) demarcation line between active galactic nuclei and H II regions in the Baldwin, Phillips, & Terlevich (BPT, 1981, PASP, 93, 5) diagram is a useful criterion to reject spectra with significantly distorted strengths of the N2 and R2 lines. We find that the three-dimensional R calibration, which uses the N2 and R2 lines, produces reliable abundances in the MaNGA galaxies. The one-dimensional N2 calibration produces either reliable or wrong abundances depending on whether excitation and N/O abundance ratio in the target region (spaxel) are close to or differ from those parameters in the calibrating points located close to the calibration relation. We then determined abundance distributions within the optical radii in the discs of 47 MaNGA galaxies. The optical radii of the galaxies were estimated from the surface brightness profiles constructed based on the
Chlorine Isotope Ratios in M Giants and S Stars
NASA Astrophysics Data System (ADS)
Maas, Zachary; Pilachowski, C. A.
2018-01-01
Chlorine is an odd-Z, light element that has been poorly studied in stars. Recently, the first stellar abundance measurements of the isotopologue 35Cl were made and the 35Cl/37Cl ratio was derived in RZ Ari (Maas et al. 2016). Additional abundance measurements are necessary to understand the Galactic chemical evolution and complex nucleosynthesis of Cl. The Cl isotope ratio in particular is important in distinguishing contributions from different nucleosynthesis sites to the surface abundances of stars. For example, current nucloesynthesis models predict that both isotopes of Cl are produced primarily during core collapse supernovae (CCSNe) with the energy and progenitor mass impacting the isotopic ratio of the ejected material. In addition to CCSNe, 37Cl is formed by the s-process both in massive stars and in AGB stars, and 35Cl may be produced from neutrino spallation. Understanding the formation of the Cl isotopes is also important to studies of the interstellar medium (ISM). A range of Cl isotope ratios mainly between 2 - 3.5 have been measured in star forming regions, in the circumstellar envelopes of evolved stars, and in proto-stellar cores using Cl bearing molecules. Additional measurements of the Cl isotope ratio in nearby stars will test nucleosynthesis models and allow comparisons with the range of isotope ratios observed in the ISM.We build on the results of Maas et al. (2016) by measuring the Cl isotope ratio in six M giants and four S stars using R~50,000 resolution spectra from Phoenix on Gemini South. We find no significant difference between the average Cl isotope ratios in the M stars and S stars and our measurements are consistent with the range of values seen in the ISM. We also find the average Cl ratio to be larger than the predicted isotope ratio of 1.8 for the solar neighborhood. Finally, two S stars, GG Pup and WY Pyx, show anomalously strong HCl features with equivalent widths ~3-5 times larger than the HCl features of other stars of
The Roles of Flares and Shocks in determining SEP Abundances
NASA Technical Reports Server (NTRS)
Cane, H. V.; Mewaldt, R. A.; Cohen, C. M. S.; vonRosenvinge, T. T.
2007-01-01
We examine solar energetic particle (SEP) event-averaged abundances of Fe relative to O and intensity versus time profiles at energies above 25 MeV/nucleon using the SIS instrument on ACE. These data are compared with solar wind conditions during each event and with estimates of the strength of the associated shock based on average travel times to 1 AU. We find that the majority of events with an Fe to 0 abundance ratio greater than two times the average 5-12 MeV/nuc value for large SEP events (0.134) occur in the western hemisphere. Furthermore, in most of these Fe-rich events the profiles peak within 12 hours of the associated flare, suggesting that some of the observed interplanetary particles are accelerated in these flares. The vast majority of events with Fe/O below 0.134 are influenced by interplanetary shock acceleration. We suggest that variations in elemental composition in SEP events mainly arise from the combination of flare particles and shock acceleration of these particles and/or the ambient medium.
Quantitative Determination of Isotope Ratios from Experimental Isotopic Distributions
Kaur, Parminder; O’Connor, Peter B.
2008-01-01
Isotope variability due to natural processes provides important information for studying a variety of complex natural phenomena from the origins of a particular sample to the traces of biochemical reaction mechanisms. These measurements require high-precision determination of isotope ratios of a particular element involved. Isotope Ratio Mass Spectrometers (IRMS) are widely employed tools for such a high-precision analysis, which have some limitations. This work aims at overcoming the limitations inherent to IRMS by estimating the elemental isotopic abundance from the experimental isotopic distribution. In particular, a computational method has been derived which allows the calculation of 13C/12C ratios from the whole isotopic distributions, given certain caveats, and these calculations are applied to several cases to demonstrate their utility. The limitations of the method in terms of the required number of ions and S/N ratio are discussed. For high-precision estimates of the isotope ratios, this method requires very precise measurement of the experimental isotopic distribution abundances, free from any artifacts introduced by noise, sample heterogeneity, or other experimental sources. PMID:17263354
Solar abundances as derived from solar energetic particles
NASA Technical Reports Server (NTRS)
Stone, E. C.
1989-01-01
Recent studies have shown that there are well defined average abundances of heavy (Z above 2) solar energetic particles (SEPs), with variations in the acceleration and propagation producing a systematic flare-to-flare fractionation that depends on the charge per unit mass of the ion. Correcting the average SEP abundances for this fractionation yields SEP-derived coronal abundances for 20 elements. High-resolution SEP studies have also provided isotopic abundances for five elements. SEP-derived abundances indicate that elements with high first ionization potentials (greater than 10 eV) are depleted in the corona relative to the photosphere and provide new information on the solar abundance of C and Ne-22.
Brand, Willi A.; Coplen, T.B.
2001-01-01
An interlaboratory comparison of forty isotope-ratio mass spectrometers of different ages from several vendors has been performed to test 2H/1H performance with hydrogen gases of three different isotopic compositions. The isotope-ratio results (unsufficiently corrected for H3+ contribution to the m/z = 3 collector, uncorrected for valve leakage in the change-over valves, etc.) expressed relative to one of these three gases covered a wide range of values: -630??? to -790??? for the second gas and -368??? to -462??? for the third gas. After normalizing the isotopic abundances of these test gases (linearly adjusting the ?? values so that the gases with the lowest and highest 2H content were identical for all laboratories), the standard deviation of the 40 measurements of the intermediate gas was a remarkably low 0.85???. It is concluded that the use of scaling factors is mandatory for providing accurate internationally comparable isotope-abundance values. Linear scaling for the isotope-ratio scales of gaseous hydrogen mass spectrometers is completely adequate. ?? Springer-Verlag 2001.
Hierarchical spatial models for predicting pygmy rabbit distribution and relative abundance
Wilson, T.L.; Odei, J.B.; Hooten, M.B.; Edwards, T.C.
2010-01-01
Conservationists routinely use species distribution models to plan conservation, restoration and development actions, while ecologists use them to infer process from pattern. These models tend to work well for common or easily observable species, but are of limited utility for rare and cryptic species. This may be because honest accounting of known observation bias and spatial autocorrelation are rarely included, thereby limiting statistical inference of resulting distribution maps. We specified and implemented a spatially explicit Bayesian hierarchical model for a cryptic mammal species (pygmy rabbit Brachylagus idahoensis). Our approach used two levels of indirect sign that are naturally hierarchical (burrows and faecal pellets) to build a model that allows for inference on regression coefficients as well as spatially explicit model parameters. We also produced maps of rabbit distribution (occupied burrows) and relative abundance (number of burrows expected to be occupied by pygmy rabbits). The model demonstrated statistically rigorous spatial prediction by including spatial autocorrelation and measurement uncertainty. We demonstrated flexibility of our modelling framework by depicting probabilistic distribution predictions using different assumptions of pygmy rabbit habitat requirements. Spatial representations of the variance of posterior predictive distributions were obtained to evaluate heterogeneity in model fit across the spatial domain. Leave-one-out cross-validation was conducted to evaluate the overall model fit. Synthesis and applications. Our method draws on the strengths of previous work, thereby bridging and extending two active areas of ecological research: species distribution models and multi-state occupancy modelling. Our framework can be extended to encompass both larger extents and other species for which direct estimation of abundance is difficult. ?? 2010 The Authors. Journal compilation ?? 2010 British Ecological Society.
Quantifying the abundance of co-occurring conifers along Inland Northwest (USA) climate gradients.
Rehfeldt, Gerald E; Ferguson, Dennis E; Crookston, Nicholas L
2008-08-01
The occurrence and abundance of conifers along climate gradients in the Inland Northwest (USA) was assessed using data from 5082 field plots, 81% of which were forested. Analyses using the Random Forests classification tree revealed that the sequential distribution of species along an altitudinal gradient could be predicted with reasonable accuracy from a single climate variable, a growing-season dryness index, calculated from the ratio of degree-days >5 degrees C that accumulate in the frost-free season to the summer precipitation. While the appearance and departure of species in an ascending altitudinal sequence were closely related to the dryness index, the departure was most easily visualized in relation to negative degree-days (degree-days < 0 degrees C). The results were in close agreement with the works of descriptive ecologists. A Weibull response function was used to predict from climate variables the abundance and occurrence probabilities of each species, using binned data. The fit of the models was excellent, generally accounting for >90% of the variance among 100 classes.
Israël, Natascha M.D.; VanLandeghem, Matthew M.; Denny, Shawn; Ingle, John; Patino, Reynaldo
2014-01-01
Prymnesium parvum (golden alga, GA) is a toxigenic harmful alga native to marine ecosystems that has also affected brackish inland waters. The first toxic bloom of GA in the western hemisphere occurred in the Pecos River, one of the saltiest rivers in North America. Environmental factors (water quality) associated with GA occurrence in this basin, however, have not been examined. Water quality and GA presence and abundance were determined at eight sites in the Pecos River basin with or without prior history of toxic blooms. Sampling was conducted monthly from January 2012 to July 2013. Specific conductance (salinity) varied spatiotemporally between 4408 and 73,786 mS/cm. Results of graphical, principal component (PCA), and zero-inflated Poisson (ZIP) regression analyses indicated that the incidence and abundance of GA are reduced as salinity increases spatiotemporally. LOWESS regression and correlation analyses of archived data for specific conductance and GA abundance at one of the study sites retrospectively confirmed the negative association between these variables. Results of PCA also suggested that at <15,000 mS/cm, GA was present at a relatively wide range of nutrient (nitrogen and phosphorus) concentrations whereas at higher salinity, GA was observed only at mid-to-high nutrient levels. Generally consistent with earlier studies, results of ZIP regression indicated that GA presence is positively associated with organic phosphorus and in samples where GA is present, GA abundance is positively associated with organic nitrogen and negatively associated with inorganic nitrogen. This is the first report of an inverse relation between salinity and GA presence and abundance in riverine waters and of interaction effects of salinity and nutrients in the field. These observations contribute to a more complete understanding of environmental conditions that influence GA distribution in inland waters.
NASA Astrophysics Data System (ADS)
McConnochie, Timothy H.; Smith, Michael D.; Wolff, Michael J.; Bender, Steve; Lemmon, Mark; Wiens, Roger C.; Maurice, Sylvestre; Gasnault, Olivier; Lasue, Jeremie; Meslin, Pierre-Yves; Harri, Ari-Matti; Genzer, Maria; Kemppinen, Osku; Martínez, Germán M.; DeFlores, Lauren; Blaney, Diana; Johnson, Jeffrey R.; Bell, James F.
2018-06-01
We derive water vapor column abundances and aerosol properties from Mars Science Laboratory (MSL) ChemCam passive mode observations of scattered sky light. This paper covers the methodology and initial results for water vapor and also provides preliminary results for aerosols. The data set presented here includes the results of 113 observations spanning from Mars Year 31 Ls = 291° (March 30, 2013) to Mars Year 33 Ls= 127° (March 24, 2016). Each ChemCam passive sky observation acquires spectra at two different elevation angles. We fit these spectra with a discrete-ordinates multiple scattering radiative transfer model, using the correlated-k approximation for gas absorption bands. The retrieval proceeds by first fitting the continuum of the ratio of the two elevation angles to solve for aerosol properties, and then fitting the continuum-removed ratio to solve for gas abundances. The final step of the retrieval makes use of the observed CO2 absorptions and the known CO2 abundance to correct the retrieved water vapor abundance for the effects of the vertical distribution of scattering aerosols and to derive an aerosol scale height parameter. Our water vapor results give water vapor column abundance with a precision of ±0.6 precipitable microns and systematic errors no larger than ±0.3 precipitable microns, assuming uniform vertical mixing. The ChemCam-retrieved water abundances show, with only a few exceptions, the same seasonal behavior and the same timing of seasonal minima and maxima as the TES, CRISM, and REMS-H data sets that we compare them to. However ChemCam-retrieved water abundances are generally lower than zonal and regional scale from-orbit water vapor data, while at the same time being significantly larger than pre-dawn REMS-H abundances. Pending further analysis of REMS-H volume mixing ratio uncertainties, the differences between ChemCam and REMS-H pre-dawn mixing ratios appear to be much too large to be explained by large scale circulations and thus
NASA Astrophysics Data System (ADS)
van der Burg, Remco F. J.; Hoekstra, Henk; Muzzin, Adam; Sifón, Cristóbal; Viola, Massimo; Bremer, Malcolm N.; Brough, Sarah; Driver, Simon P.; Erben, Thomas; Heymans, Catherine; Hildebrandt, Hendrik; Holwerda, Benne W.; Klaes, Dominik; Kuijken, Konrad; McGee, Sean; Nakajima, Reiko; Napolitano, Nicola; Norberg, Peder; Taylor, Edward N.; Valentijn, Edwin
2017-11-01
In recent years, many studies have reported substantial populations of large galaxies with low surface brightness in local galaxy clusters. Various theories that aim to explain the presence of such ultra-diffuse galaxies (UDGs) have since been proposed. A key question that will help to distinguish between models is whether UDGs have counterparts in host haloes with lower masses, and if so, what their abundance as a function of halo mass is. We here extend our previous study of UDGs in galaxy clusters to galaxy groups. We measure the abundance of UDGs in 325 spectroscopically selected groups from the Galaxy And Mass Assembly (GAMA) survey. We make use of the overlapping imaging from the ESO Kilo-Degree Survey (KiDS), from which we can identify galaxies with mean surface brightnesses within their effective radii down to 25.5 mag arcsec-2 in the r band. We are able to measure a significant overdensity of UDGs (with sizes reff ≥ 1.5 kpc) in galaxy groups down to M200 = 1012 M⊙, a regime where approximately only one in ten groups contains a UDG that we can detect. We combine measurements of the abundance of UDGs in haloes that cover three orders of magnitude in halo mass, finding that their numbers scale quite steeply with halo mass: NUDG(R < R200) ∝ M2001.11±0.07. To better interpret this, we also measure the mass-richness relation for brighter galaxies down to Mr* + 2.5 in the same GAMA groups, and find a much shallower relation of NBright(R < R200) ∝ M2000.78±0.05. This shows that compared to bright galaxies, UDGs are relatively more abundant in massive clusters than in groups. We discuss the implications, but it is still unclear whether this difference is related to a higher destruction rate of UDGs in groups or if massive haloes have a positive effect on UDG formation.
Weber, Carolyn F.; King, Gary M.; Aho, Ken
2015-01-01
Nonnative Bromus tectorum (cheatgrass) is decimating sagebrush steppe, one of the largest ecosystems in the Western United States, and is causing regional-scale shifts in the predominant plant-fungal interactions. Sagebrush, a native perennial, hosts arbuscular mycorrhizal fungi (AMF), whereas cheatgrass, a winter annual, is a relatively poor host of AMF. This shift is likely intertwined with decreased carbon (C)-sequestration in cheatgrass-invaded soils and alterations in overall soil fungal community composition and structure, but the latter remain unresolved. We examined soil fungal communities using high throughput amplicon sequencing (ribosomal large subunit gene) in the 0–4 cm and 4–8 cm depth intervals of six cores from cheatgrass- and six cores from sagebrush-dominated soils. Sagebrush core surfaces (0–4 cm) contained higher nitrogen and total C than cheatgrass core surfaces; these differences mirrored the presence of glomalin related soil proteins (GRSP), which has been associated with AMF activity and increased C-sequestration. Fungal richness was not significantly affected by vegetation type, depth or an interaction of the two factors. However, the relative abundance of seven taxonomic orders was significantly affected by vegetation type or the interaction between vegetation type and depth. Teloschistales, Spizellomycetales, Pezizales and Cantharellales were more abundant in sagebrush libraries and contain mycorrhizal, lichenized and basal lineages of fungi. Only two orders (Coniochaetales and Sordariales), which contain numerous economically important pathogens and opportunistic saprotrophs, were more abundant in cheatgrass libraries. Pleosporales, Agaricales, Helotiales and Hypocreales were most abundant across all libraries, but the number of genera detected within these orders was as much as 29 times lower in cheatgrass relative to sagebrush libraries. These compositional differences between fungal communities associated with cheatgrass- and
Coyote abundance in relation to habitat characteristics in Sierra San Luis, Sonora, Mexico
Eduardo Ponce Guevara; Karla Pelz Serrano; Carlos A. Lopez Gonzalez
2005-01-01
Coyotes have expanded their historical distribution range because of anthropogenic activities and habitat transformation, where forests have been considered marginal habitat. We tested the relationship between vegetation structure and coyote abundance in different habitat types. We expected to find a higher abundance in open lands than in thicker areas. We used scent...
Miletto, Marzia; Lindow, Steven E
2015-12-10
The study of the microbial communities in the built environment is of critical importance as humans spend the majority of their time indoors. While the microorganisms in living spaces, especially those in the air, can impact health and well-being, little is known of their identity and the processes that determine their assembly. We investigated the source-sink relationships of airborne bacteria in 29 homes in the San Francisco Bay Area. Samples taken in the sites expected to be source habitats for indoor air microbes were analyzed by 16S rRNA-based pyrosequencing and quantitative PCR. The community composition was related to the characteristics of the household collected at the time of sampling, including the number of residents and pets, activity levels, frequency of cooking and vacuum cleaning, extent of natural ventilation, and abundance and type of vegetation surrounding the building. Indoor air harbored a diverse bacterial community dominated by Diaphorobacter sp., Propionibacterium sp., Sphingomonas sp., and Alicyclobacillus sp. Source-sink analysis suggested that outdoor air was the primary source of indoor air microbes in most homes. Bacterial phylogenetic diversity and relative abundance in indoor air did not differ statistically from that in outdoor air. Moreover, the abundance of bacteria in outdoor air was positively correlated with that in indoor air, as would be expected if outdoor air was the main contributor to the bacterial community in indoor bioaerosols. The number of residents, presence of pets, and local tap water also influenced the diversity and size of indoor air microbes. The bacterial load in air increased with the number of residents, activity, and frequency of natural ventilation, and the proportion of bacteria putatively derived from skin increased with the number of residents. Vacuum cleaning increased the signature of pet- and floor-derived bacteria in indoor air, while the frequency of natural ventilation decreased the relative
Activity and the Li abundances in the FGK dwarfs⋆
NASA Astrophysics Data System (ADS)
Mishenina, T. V.; Soubiran, C.; Kovtyukh, V. V.; Katsova, M. M.; Livshits, M. A.
2012-11-01
Aims: The aim of the present study is to determine the Li abundances for a large set of the FGK dwarfs and to analyse the connections between the Li content, stellar parameters, and activity. Methods: The atmospheric parameters, rotational velocities and the Li abundances were determined from a homogeneous collection of the echelle spectra with high resolution and a high signal-to-noise ratio. The rotational velocities vsini were determined by calibrating the cross-correlation function. The effective temperatures Teff were estimated by the line-depth ratio method. The surface gravities log g were computed by two methods: the iron ionization balance and the parallax. The LTE Li abundances were computed using synthetic spectra method. The behaviour of the Li abundance was examined in correlation with Teff, [Fe/H] , as well as with vsini and the level of activity in three stellar groups of the different temperature range. Results: The stellar parameters and the Li abundances are presented for 150 slow rotating stars of the lower part of the main sequence. The studied stars show a decline in the Li abundance with decreasing temperature Teff and a significant spread, which should be due to the difference of age of stars. The correlations between the Li abundances, rotational velocities vsini, and the level of the chromospheric activity were discovered for the stars with 6000 > Teff > 5700 K, and it is tighter for the stars with 5700 > Teff > 5200 K. The target stars with Teff < 5200 K do not show any correlation between log A(Li) and vsini. The relationship between the chromospheric and coronal fluxes in active with detected Li as well as in less active stars gives a hint that there exist different conditions in the action of the dynamo mechanism in those stars. Conclusions: We found that the Li-activity correlation is evident only in a restricted temperature range and the Li abundance spread seems to be present in a group of low chromospheric activity stars that also
Evidence for the equality of the solar photospheric and coronal abundance of iron
NASA Technical Reports Server (NTRS)
Phillips, K. J. H.; Pike, C. D.; Lang, J.; Zarro, D. M.; Fludra, A.; Watanabe, T.; Takahashi, M.
1995-01-01
The Fe K-alpha and K-beta X-ray lines (wavelengths 1.94 and 1.76 A) in the solar X-ray spectrum are formed by fluoroescence of photospheric iron atoms, and the ratio of the intensity of either to the He-like iron (Fe XXV) resonance line at 1.85 A is a function of the photospheric-to-coronal abundance of iron. The temperature dependence of this ratio is weak as long as the flare temperature T(sub e) greater than or approximately equal to 15 x 10(exp 6)K. Comparison of the theoretical value of this intensity ratio with observations from crystal spectrometers on Yohkoh, Solar Maximum Mission (SMM) and P78-1 are consistent with the photospheric abundance of Fe being equal to the coronal.
Echelle Spectroscopy and Abundances in Ruprecht 106 and ARP 2
NASA Astrophysics Data System (ADS)
Brown, Jeffery A.; Wallerstein, George; Zucker, Daniel
1996-04-01
This is a preliminary report on abundances for two red giants each in the young globular clusters Ruprecht 106 and Pal 12. For Rup 106, we find [Fe/H] = -1.50 but almost all other elements are more deficient than iron, in reverse of the pattern in most metal-poor stars; the exception is oxygen, with [O/Fe] =~ 0.0. Pal 12 is less depleted, with [Fe/H] = -1.0, and has more nearly solar abundance ratios; we have no data on oxygen in Pal 12.
Composition and abundance of tree regeneration
Todd F. Hutchinson; Elaine Kennedy Sutherland; Charles T. Scott
2003-01-01
The composition and abundance of tree seedlings and saplings in the four study areas in southern Ohio were related to soil moisture via a GIS-derived integrated moisture index and to soil texture and fertility. For seedlings, the total abundance of small stems (less than 30 cm tall) was significantly greater on xeric plots (81,987/ha) than on intermediate (54,531/ha)...
Methven, David A.; Piatt, John F.
1991-01-01
The seasonal abundance and vertical distribution of capelin in relation to water temperature have been investigated by conducting repeated hydroacoustic surveys at a coastal site off eastern Newfoundland. Water temperatures were warmer in 1983 than in 1984 as indicated by the earlier appearance and greater depth of the seasonal thermocline. Correspondingly, schools of capelin appeared earlier, were more abundant, and extended deeper in the water column in 1983 than in 1984. Most capelin were found between the surface and the 5°C isotherm. In both years, initial peaks of capelin abundance occurred when nearshore water temperatures increased from about 0-1°C to above 6°C and, at or near, periods of maximum tidal oscillation. Short-term variations in the depth of the 5°C isotherm were related to nearshore wind-induced upwelling events. Annual variations corresponded to the volume of cold (>0°C) water and sea-ice transported south by the Labrador Current.
Primordial nucleosynthesis and the abundances of beryllium and boron
NASA Technical Reports Server (NTRS)
Thomas, David; Schramm, David N.; Olive, Keith A.; Fields, Brian D.
1993-01-01
The recently attained ability to make measurements of Be and B as well as to put constraints on Li-6 abundances in metal-poor stars has led to a detailed reexamination of big bang nucleosynthesis in the A is greater than about 6 regime. The nuclear reaction network has been significantly expanded, with many new rates added. It is demonstrated that although a number of A is greater than 7 reaction rates are poorly determined, even with extreme values chosen, the standard homogeneous model is unable to produce significant yields above A = 7, and the (Li-7)/(Li-6) ratio always exceeds 500. We also preliminarily explore inhomogeneous models, such as those inspired by a first-order quark-hadron phase transition, where regions with high neutron/proton ratios can allow some leakage up to A is greater than 7. However, models that fit the A is not greater than 7 abundances still seem to have difficulty in obtaining significant A is greater than 7 yields.
Abundance patterns of evolved stars with Hipparcos parallaxes and ages based on the APOGEE data base
NASA Astrophysics Data System (ADS)
Jia, Y. P.; Chen, Y. Q.; Zhao, G.; Bari, M. A.; Zhao, J. K.; Tan, K. F.
2018-01-01
We investigate the abundance patterns for four groups of stars at evolutionary phases from sub-giant to red clump (RC) and trace the chemical evolution of the disc by taking 21 individual elemental abundances from APOGEE and ages from evolutionary models with the aid of Hipparcos distances. We find that the abundances of six elements (Si, S, K, Ca, Mn and Ni) are similar from the sub-giant phase to the RC phase. In particular, we find that a group of stars with low [C/N] ratios, mainly from the second sequence of RC stars, show that there is a difference in the transfer efficiency of the C-N-O cycle between the main and the secondary RC sequences. We also compare the abundance patterns of C-N, Mg-Al and Na-O with giant stars in globular clusters from APOGEE and find that field stars follow similar patterns as M107, a metal-rich globular cluster with [M/H] ∼- 1.0, which shows that the self-enrichment mechanism represented by strong C-N, Mg-Al and Na-O anti-correlations may not be important as the metallicity reaches [M/H] > -1.0 dex. Based on the abundances of above-mentioned six elements and [Fe/H], we investigate age versus abundance relations and find some old super-metal-rich stars in our sample. Their properties of old age and being rich in metal are evidence for stellar migration. The age versus metallicity relations in low-[α/M] bins show unexpectedly positive slopes. We propose that the fresh metal-poor gas infalling on to the Galactic disc may be the precursor for this unexpected finding.
Source abundances of ultra heavy elements derived from UHCRE measurements.
Domingo, C; Font, J; Baixeras, C; Fernandez, F
1996-11-01
A total of 205 tracks have been located, measured, and positively identified as originating from Ultra Heavy (Z > or = 65) cosmic ray ions with energies over 2 GeV/amu in the 10 UHCRE plastic track detector (mainly Lexan polycarbonate) stacks studied by our Group. About 40 values of reduced etch rate S have been obtained along each of these tracks. A method based on determining the gradient of S, together with calibration in accelerators, is used to determine the charge of each ion resulting in one of such tracks to obtain the charge spectrum of the recorded Ultra Heavy ions. The abundance ratio of ions with 87 < or = Z < or = 100 to those with 74 < or = Z < or = 86 as well as that of ions with 81 < or = Z < or = 86 to those with 74 < or = Z < or = 80 are calculated at 0.016 and 0.32, respectively, which agree with the values obtained from measurements in the HEAO-3 and Ariel-6 experiments. The abundance ratio of ions with 70 < or = Z < or = 73 to those with 74 < or = Z < or = 86 is also calculated, but its value (0.074) did not seem to be significant because of our detectors' low registration efficiency in the charge range 70 < or = Z < or = 73. A computer program developed by our Group, based on the Leaky Box cosmic ray propagation model, has been used to determine the source abundances of cosmic ray nuclei with Z > or = 65 inferred from the abundances measured in the UHCRE. It appeared that r-process synthesized elements were overabundant compared to the Solar System abundances, as predicted by other authors.
NASA Astrophysics Data System (ADS)
Oseji, Ozuem F.; Chigbu, Paulinus; Oghenekaro, Efeturi; Waguespack, Yan; Chen, Nianhong
2018-07-01
The spatial and temporal variations in phytoplankton abundance and community structure in the northern and southern parts of the Maryland Coastal Bays (MCBs) that differ in anthropogenic activities and hydrological characteristics were studied in 2012 and 2013 using photosynthetic pigments as biomarkers. Phytoplankton pigment biomass and diversity were generally higher in the northern bays that receive high nutrient input from St. Martin River, than in the southern bays where nutrient levels were comparatively low. Sites close to the mouths of tributaries in northern and southern bays had higher nutrient levels, which favored the development of dinoflagellates, and nano- and picophytoplankton, than sites closer to the inlets. The microplankton dominated the phytoplankton community in spring (>90%) and decreased in relative abundance into fall (<60%) whereas nanoplankton peaked in summer or fall. Picoplankton relative abundance increased from late spring (<10%, March 2012 & 2013) to summer (40%, July 2012 and August 2013) and was correlated positively with NH4+ and negatively with salinity. The observed spatial and seasonal patterns of phytoplankton relative abundance and diversity are likely due to changes in nutrient concentrations and ratios, driven by variations in freshwater discharge, and selective grazing of phytoplankton. Water quality management in the MCBs should continue to focus on reducing nutrient inputs into the bays.
Effects of shock and Martian alteration on Tissint hydrogen isotope ratios and water content
NASA Astrophysics Data System (ADS)
Hallis, L. J.; Huss, G. R.; Nagashima, K.; Taylor, G. J.; Stöffler, D.; Smith, C. L.; Lee, M. R.
2017-03-01
The Tissint meteorite, a picritic shergottite, fell to Earth in Morocco on the 18th of July 2011, and is only the fifth Martian meteorite witnessed to fall. Hydrogen isotope ratios and water contents are variable within different minerals in Tissint. Ringwoodite and shock melt pockets contain elevated D/H ratios relative to terrestrial values (δD = 761-4224‰). These high ratios in recrystallized phases indicate significant implantation of hydrogen from the D-rich Martian atmosphere during shock. In contrast, although olivine has detectable water abundances (230-485 ppm), it exhibits much lower D/H ratios (δD = +88 to -150‰), suggesting this water was not implanted from the Martian atmosphere. The minimal terrestrial weathering experienced by Tissint gives confidence that the olivine-hosted water has a Martian origin, but its high concentration indicates direct inheritance from the parental melt is improbable, especially given the low pressure of olivine crystallisation. Incorporation of a low δD crustal fluid, or deuteric alteration during crystallisation, could explain the relatively high water contents and low D/H ratios in Tissint olivine.
An elemental abundance analysis of the superficially normal A star Vega
NASA Technical Reports Server (NTRS)
Adelman, Saul J.; Gulliver, Austin F.
1990-01-01
An elemental abundance analysis of Vega has been performed using high-signal-to-noise 2.4 A/mm Reticon observations of the region 4313-4809 A. Vega is found to be a metal-poor star with a mean underabundance of 0.60 dex. The He/H ratio of 0.03 as derived from He I 4472 A suggests that the superficial helium convection zone has disappeared and that radiative diffusion is producing the photospheric abundance anomalies.
High Precision 40K/39K Ratio Determination
NASA Astrophysics Data System (ADS)
Naumenko, M. O.; Mezger, K.; Nagler, T. F.; Villa, I. M.
2012-12-01
Potassium is one of the eight most abundant chemical elements in the Earth's crust and a major element in many rock-forming minerals. The isotope 40K is radioactive and undergoes β- decay to 40Ca (ca. 89.3%) and electron capture to 40Ar (ca. 10.7%). Both decays can potentially be used as dating systems. The most commonly used branch is the decay of 40K to 40Ar because it can yield highly precise ages. Both decay schemes rely on the knowledge of the 40K branching ratio and the natural 40K abundance. A 40K abundance of 0.011672±41 % was measured on terrestrial material [1]. The relative uncertainty of 0.35 % has not been improved since. Recent improvements in the precision of mass spectrometric measurements have led to the situation that the uncertainties on the K decay constant and the abundance of 40K are a major source of uncertainty on the measured ages. A more precise definition of the 40K decay constant was attempted by different research groups within the last decade [2-9] but the goal of obtaining 0.1 % relative uncertainty on K-Ar ages for geological materials, as requested by the EARTHtime initiative, has not been achieved yet. In order to improve on this situation we studied the abundances of the K isotopes in terrestrial standards. A ThermoFischer Triton+ thermal ionisation mass spectrometer was used for K isotope ratio measurements of the NIST SRM 918b K standard loaded on Ta filaments with 0.1M phosphoric acid. Three techniques were applied: (A) dynamic measurement with in-run normalisation to the IUPAC value 41K/39K=0.072168; (B) a simple total evaporation procedure; (C) the "NBL-modified" total evaporation [10]. The 40K ion beam was measured in a Faraday cup with a 1E12 Ω resistor; 39K and 41K were collected in Faraday cups with 1E11 Ω resistors. Amplifier gains were intercalibrated by supplying fixed voltages off-line. Different measurement techniques were combined with different loading procedures. We also tested ionisation yields for the
COMPLETE ELEMENT ABUNDANCES OF NINE STARS IN THE r -PROCESS GALAXY RETICULUM II
DOE Office of Scientific and Technical Information (OSTI.GOV)
Ji, Alexander P.; Frebel, Anna; Chiti, Anirudh
We present chemical abundances derived from high-resolution Magellan /Magellan Inamori Kyocera Echelle spectra of the nine brightest known red giant members of the ultra-faint dwarf galaxy Reticulum II (Ret II). These stars span the full metallicity range of Ret II (−3.5 < [Fe/H] < −2). Seven of the nine stars have extremely high levels of r -process material ([Eu/Fe] ∼ 1.7), in contrast to the extremely low neutron-capture element abundances found in every other ultra-faint dwarf galaxy studied to date. The other two stars are the most metal-poor stars in the system ([Fe/H] < −3), and they have neutron-capture elementmore » abundance limits similar to those in other ultra-faint dwarf galaxies. We confirm that the relative abundances of Sr, Y, and Zr in these stars are similar to those found in r -process halo stars, but they are ∼0.5 dex lower than the solar r -process pattern. If the universal r -process pattern extends to those elements, the stars in Ret II display the least contaminated known r -process pattern. The abundances of lighter elements up to the iron peak are otherwise similar to abundances of stars in the halo and in other ultra-faint dwarf galaxies. However, the scatter in abundance ratios is large enough to suggest that inhomogeneous metal mixing is required to explain the chemical evolution of this galaxy. The presence of low amounts of neutron-capture elements in other ultra-faint dwarf galaxies may imply the existence of additional r -process sites besides the source of r -process elements in Ret II. Galaxies like Ret II may be the original birth sites of r -process enhanced stars now found in the halo.« less
Koch, Robert L; Pahs, Tiffany
2014-08-01
Stink bugs (Hemiptera: Pentatomidae) have historically not been pests of soybean in Minnesota. In response to the invasion of Halyomorpha halys (Stål) and reports of increasing abundance of species native to North America, a state-wide survey of soybean was conducted over 3 yr in Minnesota to determine species composition, abundance, and seasonal dynamics of Pentatomidae associated with soybean. Fourteen species of Pentatomidae (12 herbivorous and two predatory) were collected from soybean. H. halys was not detected in this survey. Among the herbivorous species found, adults of Euschistus variolarius (Palisot de Beauvois) had the greatest relative abundance (60.51%) and frequency of detection (18.44%), followed by Euschistus servus euschistoides (Say) (19.37 and 3.04%, respectively) and Chinavia hilaris (Say) (5.50 and 1.69%, respectively). Abundance of herbivorous nymphs and adults exceeded an economic threshold (20 nymphs and adults per 100 sweeps) in 0.82% of fields in 2012 but not in 2011 or 2013. The frequency of detection of herbivorous species and ratio of nymphs to adults increased with increasing reproductive growth stage of soybean. In two of three years, herbivorous adults were more abundant in the edge compared with interior of fields. Two predatory Pentatomidae, Podisus maculiventris (Say) and Podisus placidus Uhler, comprised 5.95 and 1.62% of the pentatomid adults. Though the species composition of Pentatomidae in Minnesota soybean differs from that in eastern and southern states, the spatial (i.e., greater abundance near field edge) and seasonal dynamics (i.e., increasing abundance and reproduction with increasing reproductive maturity of soybean) in soybean appear similar.
Abundance models improve spatial and temporal prioritization of conservation resources.
Johnston, Alison; Fink, Daniel; Reynolds, Mark D; Hochachka, Wesley M; Sullivan, Brian L; Bruns, Nicholas E; Hallstein, Eric; Merrifield, Matt S; Matsumoto, Sandi; Kelling, Steve
2015-10-01
Conservation prioritization requires knowledge about organism distribution and density. This information is often inferred from models that estimate the probability of species occurrence rather than from models that estimate species abundance, because abundance data are harder to obtain and model. However, occurrence and abundance may not display similar patterns and therefore development of robust, scalable, abundance models is critical to ensuring that scarce conservation resources are applied where they can have the greatest benefits. Motivated by a dynamic land conservation program, we develop and assess a general method for modeling relative abundance using citizen science monitoring data. Weekly estimates of relative abundance and occurrence were compared for prioritizing times and locations of conservation actions for migratory waterbird species in California, USA. We found that abundance estimates consistently provided better rankings of observed counts than occurrence estimates. Additionally, the relationship between abundance and occurrence was nonlinear and varied by species and season. Across species, locations prioritized by occurrence models had only 10-58% overlap with locations prioritized by abundance models, highlighting that occurrence models will not typically identify the locations of highest abundance that are vital for conservation of populations.
Fluorine Abundances of AGB Stars in Stellar Clusters
NASA Astrophysics Data System (ADS)
Hren, A.; Lebzelter, T.; Aringer, B.; Hinkle, K. H.; Nowotny, W.
2015-08-01
We have measured the abundance of fluorine, [F/Fe], in a number of AGB stars in stellar clusters have correlated the results with their C/O ratios. This allows us to investigate the change in the fluorine abundance along the evolution on the giant branch. The target list includes primarily O-rich stars in three LMC globular clusters - NGC 1806, NGC 1846 and NGC 1978 - as well as Rup 106 and 47 Tuc in our Galaxy. The observational data were obtained with the PHOENIX spectrograph, and the COMA code was used for modelling the synthetic spectra. Within individual clusters, we find consistent [F/Fe] values at similar C/O for most of our target stars.
NASA Astrophysics Data System (ADS)
Ilieva-Makulec, K.; Bjarnadottir, B.; Sigurdsson, B. D.
2014-10-01
The soil nematode fauna can give important insights into soil development and other habitat changes that occur during primary succession. We investigated the generic composition, density, distribution and community structure of nematodes 50 years after the formation of a pristine volcanic island, Surtsey, Iceland. Part of the island has received additional nutrient inputs from seagulls breeding there since 1985, while the reminder has been much less affected and is at present found at a different successional sere. In total, 25 genera of nematodes were identified, of which 14 were reported on Surtsey for the first time. Nematode communities were more diverse in the more infertile area outside the gull colony, where 24 genera were found, compared to 18 inside. The trophic structure of the nematode communities showed relatively higher abundance of fungal feeders in the infertile areas, but relatively more bacterial- and plant-feeders inside the colony. Nematode abundance in surface soil was, however, significantly higher within the gull colony, with 16.7 ind. cm-2 compared to 3.6 ind. cm-2 outside. A multivariate analysis indicated that the nematode abundance and distribution on Surtsey were most strongly related to the soil C : N ratio, soil acidity, plant cover and biomass, soil temperature and soil depth.
High-resolution mapping of elemental abundances of the lunar regolith
NASA Astrophysics Data System (ADS)
Wöhler, Christian; Berezhnoy, Alexey; Evans, Richard
Many attempts have been made to derive elemental abundances of the lunar surface from mul-tispectral images (cf. e.g. [1]). The gamma ray spectrometer on board the Lunar Prospector spacecraft (LP GRS) provided the first "direct" global measurements of lunar elemental abun-dances including Fe, Th (15 km surface resolution), Ti, K, Sm (60 km), Al, O, Si, Mg, Ca, and U (150 km). In this study we rely on the elemental abundance estimation method intro-duced in [2], which is based on spectral features derived from the Clementine UVVIS+NIR data set and estimates the abundances of Ca, Al, Fe, Mg, Ti, and O by applying a second order polynomial regression model with the corresponding LP GRS abundances as "ground truth". The regarded spectral features are the continuum slope, the FWHM of the ferrous absorption trough near 1000 nm after continuum division, and the absorption wavelengths and relative absorption depths (cf. [2,3] for details). A petrographic analysis is performed based on the abundances of the key elements Al, Fe, and Mg [4]. The relative abundances of the endmem-bers mare basalt, Mg-rich rock, and ferroan anorthosite are estimated using Fe-Mg and Al-Mg diagrams, where the endmember compositions are determined based on the three-endmember plane fitted in Al-Fe-Mg space to the elemental abundances at 150 km resolution obtained with the regression model. The root-mean-square deviation from the three-endmember plane is only 0.3 wt percent. Our petrographic map shows Mg-rich rocks in the Mare Frigoris region, on the edges of large maria, in the South Pole Aitken basin, and in some cryptomaria such as the Schiller-Schickard basin. The presence of Mg-rich rocks in Mare Frigoris explains the Fe and Ti depletion discussed in [5]. Furthermore, our analysis confirms that the basalts of eastern mare Frigoris have an atypically high Al content [6]. The region south of Lichtenberg and around Seleucus and Briggs in northwestern Oceanus Procellarum is characterised by
Yong Wang; Deborah M. Finch
2002-01-01
We compared consistency of species richness and relative abundance data collected concurrently using mist netting and point counts during migration in riparian habitats along the middle Rio Grande of central New Mexico. Mist netting detected 74% and point counts detected 82% of the 197 species encountered during the study. Species that mist netting failed to capture...
Merten, Eric C.; Hemstad, Nathaniel A.; Eggert, L.S.; Johnson, L.B.; Kolka, R.K.; Newman, Raymond M.; Vondracek, Bruce C.
2015-01-01
Short-term effects of forest harvest on fish habitat have been well documented, including sediment inputs, leaf litter reductions, and stream warming. However, few studies have considered changes in local climate when examining postlogging changes in fish communities. To address this need, we examined fish abundances between 1997 and 2007 in a basin in a northern hardwood forest. Streams in the basin were subjected to experimental riparian forest harvest in fall 1997. We noted a significant decrease for fish index of biotic integrity and abundance of Salvelinus fontinalis and Phoxinus eos over the study period. However, for P. eos and Culaea inconstans, the temporal patterns in abundances were related more to summer air temperatures than to fine sediment or spring precipitation when examined using multiple regressions. Univariate regressions suggested that summer air temperatures influenced temporal patterns in fish communities more than fine sediment or spring precipitation.
Transition Element Abundances in MORB Basalts
NASA Astrophysics Data System (ADS)
Yang, S.; Humayun, M.; Salters, V. J.; Fields, D.; Jefferson, G.; Perfit, M. R.
2012-12-01
The mineralogy of the mantle sources of basalts is an important, but hard to constrain parameter, especially with the basalts as chemical probes of major element mantle composition. Geophysical models imply that the deep mantle may have significant variations in Fe and Si relative to the ambient mantle sampled by MORB. Some petrological models of sub-ridge melting involve both pyroxenite and peridotite, implying that basalts preferentially sample a pyroxenite endmember. The First-Row Transition Elements (FRTE), Ga and Ge are compatible to moderately incompatible during partial melting, and are sensitive to mineralogical variability in the mantle and thus can provide constraints on mantle source mineralogy for MORB. We have analyzed major elements, FRTE, Ga and Ge on 231 basaltic glasses from the Middle Atlantic Ridge (MAR between -23°S to 36.44°N), 30 Mid-Cayman Rise basaltic glasses, 12 glasses from the Siqueiros Fracture Zone (EPR), 9 glasses from the Blanco Trough, Juan de Fuca ridge, and Galapagos Spreading Centers (EPR), and 4 Indian Ocean MORB. Large spots (150 μm) were precisely (±1%) analyzed by a New Wave UP193FX excimer (193 nm) laser ablation system coupled to a high-resolution ICP-MS at the National High Magnetic Field Laboratory using a high ablation rate (50 Hz) to yield blank contributions <1% for all elements, particularly Ge. The data demonstrate that the Ge/Si (6.96 x 10E-6 ± 3%, 1σ) and Fe/Mn (55 ± 2%) ratios for MORB are insensitive to fractional crystallization within the MgO range 6%-10%. MORB have Zn/Fe (9.9 x 10E-4 ± 7%), Ga/Sc (0.37-0.50), Ga/Al (2.2 x 10E-4 ± 11%) ratios, with the variations mostly due to the effects of fractional crystallization. Recent experimental determination of FRTE, Ga and Ge partition coefficients provide a framework within which to interpret these data [1]. Using these new partition coefficients, we have modeled the sensitivity of each element to mineralogical variations in the mantle source. Olivine
NASA Astrophysics Data System (ADS)
Henderson, Peter A.
2017-09-01
Changes in temporal and spatial composition of the British inshore North Sea fish community are reviewed. Sampling from the cooling water filter screens of power stations bordering the North Sea commenced in the early 1960s. To date, a total of 112 marine fish species have been recorded, a high proportion of the total inshore fish species complement of shallow North Sea British waters. The unrecorded top predators, such as large sharks, swordfish and tuna are not regularly observed in waters < 20 m deep. The greatest species number (92) is reported from fully marine waters in East Anglia. A group of 18 ubiquitous, high abundance, taxa form a core inshore community throughout the region in both estuarine and marine waters. They show a high level of concordance in relative abundance along the British east coast from the 1970s to the present. A second group of 20 species are abundant, but more restricted in habitat. Where they do occur, this group are usually always present and form together with the ubiquitous taxa the local core community. The third group of 67 species, are never abundant and are restricted in occurrence both spatially and temporally. Total species richness declines between 50 and 56°N, probably because high summer temperatures allow the southern North Sea to support summer migrants entering via the English Channel. Since the 1960s there has been a notable recovery in fish diversity and abundance in large industrialised estuaries such as the Thames and the Firth of Forth. Linked to spawning and nursery habitat gain, smelt, Osmerus eperlangus, and bass, Dicentrarchus labrax, have greatly increased in abundance. There is no evidence for a decline in species richness since the 1970s. However, elasmobranch species number has declined while two species Raja clavata and Scyliorhinus canicula have remained abundant and one, Mustelus asterias, has increased in abundance. It is argued that overexploitation and habitat destruction remain, as they have been
Abundances and energy spectra of high energy heavy cosmic-ray nuclei
DOE Office of Scientific and Technical Information (OSTI.GOV)
Barthelmy, S.D.
1985-01-01
We have measured the relative abundances of the cosmic rays in the iron group region at energies from a few GeV/amu to approximately 70 GeV/amu. This is done using a balloon-borne instrument consisting of gas ionization chambers, a plastic scintillator, a plastic Cherenkov counter, and a CO/sub 2/ gas Cherenkov counter. The instrument was flown from Palestine, Texas in the fall of 1982 for a total exposure of 62 m/sup 2/-ster-hr at an average atmospheric depth of 4 g/cm/sup 2/. The elemental charge was determined for a combination of the scintillator and plastic Cherenkov detector. Results are reported on themore » /sub 22/Ti//sub 26/Fe, /sub 24/Cr//sub 26/Fe, /sub 20/Ca//sub 26/Fe, and /sub 28/Ni//sub 28/Fe abundance ratios from 2 to 70 GeV/amu. Within this work results on the previously unused method of relativistic rise in gas ionization chambers is detailed as well as results on the return to nonsaturation of plastic scintillators.« less
NASA Technical Reports Server (NTRS)
Millar, T. J.; Defrees, D. J.; Mclean, A. D.; Herbst, E.
1988-01-01
The approach of Bates to the determination of neutral product branching ratios in ion-electron dissociative recombination reactions has been utilized in conjunction with quantum chemical techniques to redetermine branching ratios for a wide variety of important reactions of this class in dense interstellar clouds. The branching ratios have then been used in a pseudo time-dependent model calculation of the gas phase chemistry of a dark cloud resembling TMC-1 and the results compared with an analogous model containing previously used branching ratios. In general, the changes in branching ratios lead to stronger effects on calculated molecular abundances at steady state than at earlier times and often lead to reductions in the calculated abundances of complex molecules. However, at the so-called 'early time' when complex molecule synthesis is most efficient, the abundances of complex molecules are hardly affected by the newly used branching ratios.
Reduction of the K* meson abundance in heavy ion collisions
NASA Astrophysics Data System (ADS)
Cho, Sungtae; Lee, Su Houng
2018-03-01
We study the K* meson reduction in heavy-ion collisions by focusing on the hadronic effects on the K* meson abundance. We evaluate the absorption cross sections of the K* and K meson by light mesons in the hadronic matter, and further investigate the variation in the meson abundances for both particles during the hadronic stage of heavy-ion collisions. We show how the interplay between the interaction of the K* meson and kaon with light mesons in the hadronic medium determines the final yield difference of the statistical hadronization model to the experimental measurements. For the central Au+Au collision at √{sN N}=200 GeV, we find that the K*/K yield ratio at chemical freeze-out decreases by 37 % during the expansion of the hadronic matter, resulting in the final ratio comparable to STAR measurements of 0.23 ±0.05 .
VizieR Online Data Catalog: Barred & unbarred galaxies N, O abundance ratio (Florido+, 2015)
NASA Astrophysics Data System (ADS)
Florido, E.; Zurita, A.; Perez, I.; Perez-Montero, E.; Coelho, P. R. T.; Gadotti, D. A.
2015-11-01
The tables contain nebular emission line fluxes for the central region of 251 barred and 324 unbarred galaxies. The sample contains all spiral face-on galaxies (axial ratio b/a>=0.9) in the SDSS DR-2, with stellar masses larger than 1010 the solar mass, redshift 0.02
Smith, Griffin W; Debinski, Diane M; Scavo, Nicole A; Lange, Corey J; Delaney, John T; Moranz, Raymond A; Miller, James R; Engle, David M; Toth, Amy L
2016-04-01
Grasslands provide important resources for pollinators in agricultural landscapes. Managing grasslands with fire and grazing has the potential to benefit plant and pollinator communities, though there is uncertainty about the ideal approach. We examined the relationships among burning and grazing regimes, plant communities, and Bombus species and Apis mellifera L. abundance and nutritional indicators at the Grand River Grasslands in southern Iowa and northern Missouri. Treatment regimes included burn-only, grazed-and-burned, and patch-burn graze (pastures subdivided into three temporally distinct fire patches with free access by cattle). The premise of the experimental design was that patch-burn grazing would increase habitat heterogeneity, thereby providing more diverse and abundant floral resources for pollinators. We predicted that both bee abundance and individual bee nutritional indicators (bee size and lipid content) would be positively correlated with floral resource abundance. There were no significant differences among treatments with respect to bee abundance. However, some of the specific characteristics of the plant community showed significant relationships with bee response variables. Pastures with greater abundance of floral resources had greater bee abundance but lower bee nutritional indicators. Bee nutritional variables were positively correlated with vegetation height, but, in some cases, negatively correlated with stocking rate. These results suggest grassland site characteristics such as floral resource abundance and stocking rate are of potential importance to bee pollinators and suggest avenues for further research to untangle the complex interactions between grassland management, plant responses, and bee health. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
Coronal Abundances and Their Variation
NASA Technical Reports Server (NTRS)
Saba, Julia L. R.
1996-01-01
This contract supported the investigation of elemental abundances in the solar corona, principally through analysis of high-resolution soft X-ray spectra from the Flat Crystal Spectrometer on NASA's Solar Maximum Mission. The goals of the study were a characterization of the mean values of relative abundances of elements accessible in the FCS data, and information on the extent and circumstances of their variability. This is the Final Report, summarizing the data analysis and reporting activities which occurred during the period of performance, June 1993 - December 1996.
The relative abundances of Sn, Te, Xe, Ba and Ce. Ph.D. Thesis
NASA Technical Reports Server (NTRS)
Krombel, K. E.
1983-01-01
Elements with even atomic number (Z) in the interval 50 or = Z or = 58 were resolved in the cosmic radiation using the Heavy Nuclei Experiment on the HEAO-3 satellite. Their relative abundances were compared with the results expected from pure r-process material, pure s-process material, and solar system material, both with and without a modification due to possible first ionization potential effects. Such effects may be the result of the preferential acceleration, and hence enhancement in the cosmic rays, of those elements having low first ionization potentials. Measurements were found to be inconsistent with pure r-process material at the greater than 98% confidence level whether or not the first ionization potential adjustments are made.
XMM-Newton Observations of NGC 507: Supersolar Metal Abundances in the Hot Interstellar Medium
NASA Astrophysics Data System (ADS)
Kim, Dong-Woo; Fabbiano, Giuseppina
2004-10-01
We present the results of the X-ray XMM-Newton observations of NGC 507, a dominant elliptical galaxy in a small group of galaxies, and report supersolar metal abundances of both Fe and α-elements in the hot interstellar medium (ISM) of this galaxy. These results are robust in that we considered all possible systematic effects in our analysis. We find ZFe=2-3 times solar inside the D25 ellipse of NGC 507. This is the highest ZFe reported so far for the hot halo of an elliptical galaxy; this high iron abundance is fully consistent with the predictions of stellar evolution models, which include the yield of both Type II and Type Ia supernovae (SNe). Our analysis shows that abundance measurements are critically dependent on the selection of the proper emission model. The spatially resolved, high-quality XMM-Newton spectra provide enough statistics to formally require at least three emission components in each of four circumnuclear concentric shells (within 5' or 100 kpc): two soft thermal components indicating a range of temperatures in the hot ISM plus a harder component, consistent with the integrated output of low-mass X-ray binaries (LMXBs) in NGC 507. The two-component (thermal+LMXB) model customarily used in past studies yields a much lower ZFe, consistent with previous reports of subsolar metal abundances. This model, however, gives a significantly worse fit to the data (F-test probability<0.0001). The abundance of α-elements (most accurately determined by Si) is also found to be supersolar. The α-element-to-Fe abundance ratio is close to the solar ratio, suggesting that ~70% of the iron mass in the hot ISM originated from Type Ia SNe. The α-element-to-Fe abundance ratio remains constant out to at least 100 kpc, indicating that Types II and Ia SN ejecta are well mixed on a scale much larger than the extent of the stellar body.
Stellar Abundance Observations and Heavy Element Formation
NASA Astrophysics Data System (ADS)
Cowan, J. J.
2005-05-01
Abundance observations indicate the presence of rapid-neutron capture (i.e., r-process) elements in old Galactic halo and globular cluster stars. These observations provide insight into the nature of the earliest generations of stars in the Galaxy -- the progenitors of the halo stars -- responsible for neutron-capture synthesis of the heavy elements. Abundance comparisons among the r-process-rich halo stars show that the heaviest neutron-capture elements (i.e., Ba and above) are consistent with a scaled solar system r-process abundance distribution, while the lighter neutron-capture elements do not conform to the solar pattern. These comparisons suggest the possibility of two r-process sites in stars. The large star-to-star scatter observed in the abundances of neutron-capture element/iron ratios at low metallicities -- which disappears with increasing metallicity or [Fe/H] -- suggests the formation of these heavy elements (presumably from certain types of supernovae) was rare in the early Galaxy. The stellar abundances also indicate a change from the r-process to the slow neutron capture (i.e., s-) process at higher metallicities in the Galaxy and provide insight into Galactic chemical evolution. Finally, the detection of thorium and uranium in halo and globular cluster stars offers an independent age-dating technique that can put lower limits on the age of the Galaxy, and hence the Universe. This work has been supported in part by NSF grant AST 03-07279 (J.J.C.) and by STScI grants GO-8111, GO-8342 and GO-9359.
NASA Astrophysics Data System (ADS)
Sobocinski, Kathryn L.; Ciannelli, Lorenzo; Wakefield, W. Waldo; Yergey, Matthew E.; Johnson-Colegrove, Angela
2018-05-01
The juvenile demersal fish assemblage along the Pacific Northwest coast has received little attention relative to adult life history stages since pioneering work in the 1970s. Increasing severity of hypoxia along the Oregon coast in recent years has prompted investigations into the response of biota in this region. We used summer data (2008-2013) from a beam trawl survey targeting juvenile demersal fishes in soft-bottom habitats along the Oregon coast to describe patterns of distribution and abundance at fixed sampling stations (from 30 m to 100 m depth). We relate the assemblage and abundance of the common species to environmental variables and analyze condition of recently settled fish (<50 mm SL). Most of the captured fishes were young-of-the-year flatfishes, dominated by Butter Sole (Isopsetta isolepis), English Sole (Parophrys vetulus), Speckled Sanddab (Citharichthys stigmaeus), and Pacific Sanddab (Citharichthys sordidus). Community analysis of the full dataset showed some variation in species richness among years and high evenness across all sampling sites and years. Depth was a structuring variable for the community, indicated by multivariate nonmetric multidimensional scaling analysis. Generalized additive models for common flatfish species abundances during the summer months indicated depth preferences, with Butter Sole, English Sole, and Speckled Sanddab at shallower locations and Pacific Sanddab occurring at deeper locations farther offshore. Additionally, while most common species were collected in high abundances in hypoxic conditions, dissolved oxygen was a significant factor in determining flatfish abundance. Condition factor was weakly negatively impacted by low dissolved oxygen for the species assessed, but the strength of the relationship varied by species. Increased sampling frequency and spatial coverage would improve our understanding of this community, especially in light of changing environmental drivers such as decreasing pH, warming water
Meng, Jia; Li, Jiuling; Li, Jianzheng; Astals, Sergi; Nan, Jun; Deng, Kaiwen; Antwi, Philip; Xu, Pianpian
2018-07-01
This study investigated the role of COD/N ratio on the start-up and performance of an upflow microaerobic sludge reactor (UMSR) treating piggery wastewater at 0.5 mgO 2 /L. At high COD/N ratio (6.24 and 4.52), results showed that the competition for oxygen between ammonia-oxidizing bacteria, nitrite-oxidizing bacteria and heterotrophic bacteria limited the removal of nitrogen. Nitrogen removal efficiency was below 40% in both scenarios. Decreasing the influent COD/N ratio to 0.88 allowed achieving high removal efficiencies for COD (∼75%) and nitrogen (∼85%) due to the lower oxygen consumption for COD mineralization. Molecular biology techniques showed that nitrogen conversion at a COD/N ratio 0.88 was dominated by the anammox pathway and that Candidatus Brocadia sp. was the most important anammox bacteria in the reactor with a relative abundance of 58.5% among the anammox bacteria. Molecular techniques also showed that Nitrosomonas spp. was the major ammonia-oxidiser bacteria (relative abundance of 86.3%) and that denitrification via NO 3 - and NO 2 - also contributed to remove nitrogen from the system. Copyright © 2018 Elsevier Ltd. All rights reserved.
Interstellar abundances - Gas and dust
NASA Technical Reports Server (NTRS)
Field, G. B.
1974-01-01
Data on abundances of interstellar atoms, ions and molecules in front of zeta Oph are assembled and analyzed. The gas-phase abundances of at least 11 heavy elements are significantly lower, relative to hydrogen, than in the solar system. The abundance deficiencies of certain elements correlate with the temperatures derived theoretically for particle condensation in stellar atmospheres or nebulae, suggesting that these elements have condensed into dust grains near stars. There is evidence that other elements have accreted onto such grains after their arrival in interstellar space. The extinction spectrum of zeta Oph can be explained qualitatively and, to a degree, quantitatively by dust grains composed of silicates, graphite, silicon carbide, and iron, with mantles composed of complex molecules of H, C, N, and O. This composition is consistent with the observed gas-phase deficiencies.
NASA Technical Reports Server (NTRS)
Roth, Nathan X.; Gibb, Erika; Bonev, Boncho P.; Disanti, Michael A.; Mumma, Michael J.; Villanueva, Geronimo L.; Paganini, Lucas
2017-01-01
On 2014 May 22 and 24 we characterized the volatile composition of the dynamically new Oort cloud comet C2012 K1 (PanSTARRS) using the long-slit, high resolution ( lambda/delta lambda is approximately or equal to 25,000) near-infrared echelle spectrograph (NIRSPEC) at the 10 m Keck II telescope on Maunakea, Hawaii. We detected fluorescent emission from six primary volatiles (H2O, HCN, CH4, C2H6, CH3OH, and CO). Upper limits were derived for C2H2, NH3, and H2CO. We report rotational temperatures, production rates, and mixing ratios (relative to water). Compared with median abundance ratios for primary volatiles in other sampled Oort cloud comets, trace gas abundance ratios in C2012 K1 (PanSTARRS) for CO and HCN are consistent, but CH3OH and C2H6 are enriched while H2CO, CH4, and possibly C2H2 are depleted. When placed in context with comets observed in the near- infrared to date, the data suggest a continuous distribution of abundances of some organic volatiles (HCN, C2H6, CH3OH, CH4) among the comet population. The level of enrichment or depletion in a given comet does not necessarily correlate across all molecules sampled, suggesting that chemical diversity among comets may be more complex than the simple organics-enriched, organics-normal, and organics-depleted framework.
Nislow, K.H.; Hudy, M.; Letcher, B.H.; Smith, E.P.
2011-01-01
1.Barriers to immigration, all else being equal, should in principle depress local abundance and reduce local species richness. These issues are particularly relevant to stream-dwelling species when improperly designed road crossings act as barriers to migration with potential impacts on the viability of upstream populations. However, because abundance and richness are highly spatially and temporally heterogeneous and the relative importance of immigration on demography is uncertain, population- and community-level effects can be difficult to detect. 2.In this study, we tested the effects of potential barriers to upstream movements on the local abundance and species richness of a diverse assemblage of resident stream fishes in the Monongahela National Forest, West Virginia, U.S.A. Fishes were sampled using simple standard techniques above- and below road crossings that were either likely or unlikely to be barriers to upstream fish movements (based on physical dimensions of the crossing). We predicted that abundance of resident fishes would be lower in the upstream sections of streams with predicted impassable barriers, that the strength of the effect would vary among species and that variable effects on abundance would translate into lower species richness. 3.Supporting these predictions, the statistical model that best accounted for variation in abundance and species richness included a significant interaction between location (upstream or downstream of crossing) and type (passable or impassable crossing). Stream sections located above predicated impassable culverts had fewer than half the number of species and less than half the total fish abundance, while stream sections above and below passable culverts had essentially equivalent richness and abundance. 4.Our results are consistent with the importance of immigration and population connectivity to local abundance and species richness of stream fishes. In turn, these results suggest that when measured at
McConnochie, Timothy H.; Smith, Michael D.; Wolff, Michael J.; ...
2017-11-03
In this work, we derive water vapor column abundances and aerosol properties from Mars Science Laboratory (MSL) ChemCam passive mode observations of scattered sky light. This paper covers the methodology and initial results for water vapor and also provides preliminary results for aerosols. The data set presented here includes the results of 113 observations spanning from Mars Year 31 L s = 291° (March 30, 2013) to Mars Year 33 L s= 127° (March 24, 2016). Each ChemCam passive sky observation acquires spectra at two different elevation angles. We fit these spectra with a discrete-ordinates multiple scattering radiative transfer model,more » using the correlated-k approximation for gas absorption bands. The retrieval proceeds by first fitting the continuum of the ratio of the two elevation angles to solve for aerosol properties, and then fitting the continuum-removed ratio to solve for gas abundances. The final step of the retrieval makes use of the observed CO 2 absorptions and the known CO 2 abundance to correct the retrieved water vapor abundance for the effects of the vertical distribution of scattering aerosols and to derive an aerosol scale height parameter. Our water vapor results give water vapor column abundance with a precision of ±0.6 precipitable microns and systematic errors no larger than ±0.3 precipitable microns, assuming uniform vertical mixing. The ChemCam-retrieved water abundances show, with only a few exceptions, the same seasonal behavior and the same timing of seasonal minima and maxima as the TES, CRISM, and REMS-H data sets that we compare them to. However ChemCam-retrieved water abundances are generally lower than zonal and regional scale from-orbit water vapor data, while at the same time being significantly larger than pre-dawn REMS-H abundances. Pending further analysis of REMS-H volume mixing ratio uncertainties, the differences between ChemCam and REMS-H pre-dawn mixing ratios appear to be much too large to be explained by large
DOE Office of Scientific and Technical Information (OSTI.GOV)
McConnochie, Timothy H.; Smith, Michael D.; Wolff, Michael J.
In this work, we derive water vapor column abundances and aerosol properties from Mars Science Laboratory (MSL) ChemCam passive mode observations of scattered sky light. This paper covers the methodology and initial results for water vapor and also provides preliminary results for aerosols. The data set presented here includes the results of 113 observations spanning from Mars Year 31 L s = 291° (March 30, 2013) to Mars Year 33 L s= 127° (March 24, 2016). Each ChemCam passive sky observation acquires spectra at two different elevation angles. We fit these spectra with a discrete-ordinates multiple scattering radiative transfer model,more » using the correlated-k approximation for gas absorption bands. The retrieval proceeds by first fitting the continuum of the ratio of the two elevation angles to solve for aerosol properties, and then fitting the continuum-removed ratio to solve for gas abundances. The final step of the retrieval makes use of the observed CO 2 absorptions and the known CO 2 abundance to correct the retrieved water vapor abundance for the effects of the vertical distribution of scattering aerosols and to derive an aerosol scale height parameter. Our water vapor results give water vapor column abundance with a precision of ±0.6 precipitable microns and systematic errors no larger than ±0.3 precipitable microns, assuming uniform vertical mixing. The ChemCam-retrieved water abundances show, with only a few exceptions, the same seasonal behavior and the same timing of seasonal minima and maxima as the TES, CRISM, and REMS-H data sets that we compare them to. However ChemCam-retrieved water abundances are generally lower than zonal and regional scale from-orbit water vapor data, while at the same time being significantly larger than pre-dawn REMS-H abundances. Pending further analysis of REMS-H volume mixing ratio uncertainties, the differences between ChemCam and REMS-H pre-dawn mixing ratios appear to be much too large to be explained by large
DOE Office of Scientific and Technical Information (OSTI.GOV)
Nagasawa, D. Q.; Marshall, J. L.; Li, T. S.
We present chemical abundance measurements of three stars in the ultrafaint dwarf galaxy Horologium I, a Milky Way satellite discovered by the Dark Energy Survey. Using high-resolution spectroscopic observations, we measure the metallicity of the three stars, as well as abundance ratios of several α-elements, iron-peak elements, and neutron-capture elements. The abundance pattern is relatively consistent among all three stars, which have a low average metallicity of [Fe/H] ~ –2.6 and are not α-enhanced ([α/Fe] ~ 0.0). This result is unexpected when compared to other low-metallicity stars in the Galactic halo and other ultrafaint dwarfs and suggests the possibility ofmore » a different mechanism for the enrichment of Hor I compared to other satellites. Here, we discuss possible scenarios that could lead to this observed nucleosynthetic signature, including extended star formation, enrichment by a Population III supernova, and or an association with the Large Magellanic Cloud.« less
Nagasawa, D. Q.; Marshall, J. L.; Li, T. S.; ...
2018-01-11
We present chemical abundance measurements of three stars in the ultrafaint dwarf galaxy Horologium I, a Milky Way satellite discovered by the Dark Energy Survey. Using high-resolution spectroscopic observations, we measure the metallicity of the three stars, as well as abundance ratios of several α-elements, iron-peak elements, and neutron-capture elements. The abundance pattern is relatively consistent among all three stars, which have a low average metallicity of [Fe/H] ~ –2.6 and are not α-enhanced ([α/Fe] ~ 0.0). This result is unexpected when compared to other low-metallicity stars in the Galactic halo and other ultrafaint dwarfs and suggests the possibility ofmore » a different mechanism for the enrichment of Hor I compared to other satellites. Here, we discuss possible scenarios that could lead to this observed nucleosynthetic signature, including extended star formation, enrichment by a Population III supernova, and or an association with the Large Magellanic Cloud.« less
Merten, Eric C.; Hemstad, Nathaniel A.; Eggert, S.L.; Johnson, L.B.; Kolka, Randall K.; Newman, Raymond M.; Vondracek, Bruce C.
2010-01-01
Short-term effects of forest harvest on fish habitat have been well documented, including sediment inputs, leaf litter reductions, and stream warming. However, few studies have considered changes in local climate when examining postlogging changes in fish communities. To address this need, we examined fish abundances between 1997 and 2007 in a basin in a northern hardwood forest. Streams in the basin were subjected to experimental riparian forest harvest in fall 1997. We noted a significant decrease for fish index of biotic integrity and abundance of Salvelinus fontinalis and Phoxinus eos over the study period. However, for P. eos and Culaea inconstans, the temporal patterns in abundances were related more to summer air temperatures than to fine sediment or spring precipitation when examined using multiple regressions. Univariate regressions suggested that summer air temperatures influenced temporal patterns in fish communities more than fine sediment or spring precipitation.
Calculation of primordial abundances of light nuclei including a heavy sterile neutrino
DOE Office of Scientific and Technical Information (OSTI.GOV)
Mosquera, M.E.; Civitarese, O., E-mail: mmosquera@fcaglp.unlp.edu.ar, E-mail: osvaldo.civitarese@fisica.unlp.edu.ar
2015-08-01
We include the coupling of a heavy sterile neutrino with active neutrinos in the calculation of primordial abundances of light-nuclei. We calculate neutrino distribution functions and primordial abundances, as functions depending on a renormalization of the sterile neutrino distribution function (a), the sterile neutrino mass (m{sub s}) and the mixing angle (φ). Using the observable data, we set constrains on these parameters, which have the values 0a < 0.4, sin{sup 2} φ ≈ 0.12−0.39 and 0m{sub s} < 7 keV at 1σ level, for a fixed value of the baryon to photon ratio. When the baryon to photon ratio is allowed to vary, its extracted value ismore » in agreement with the values constrained by Planck observations and by the Wilkinson Microwave Anisotropy Probe (WMAP). It is found that the anomaly in the abundance of {sup 7}Li persists, in spite of the inclusion of a heavy sterile neutrino.« less
Newell, P.; King, S.
2009-01-01
Partial cutting techniques are increasingly advocated and used to create habitat for priority wildlife. However, partial cutting may or may not benefit species dependent on deadwood; harvesting can supplement coarse woody debris in the form of logging slash, but standing dead trees may be targeted for removal. We sampled cerambycid beetles during the spring and summer of 2006 and 2007 with canopy malaise traps in 1- and 2-year-old partial cut and uncut bottomland hardwood forests of Louisiana. We captured a total of 4195 cerambycid beetles representing 65 species. Relative abundance was higher in recent partial cuts than in uncut controls and with more dead trees in a plot. Total species richness and species composition were not different between treatments. The results suggest partial cuts with logging slash left on site increase the abundance of cerambycid beetles in the first few years after partial cutting and that both partial cuts and uncut forest should be included in the bottomland hardwood forest landscape.
Stable isotope ratio mass spectrometry of nanogram quantities of boron and sulfur
NASA Astrophysics Data System (ADS)
Wieser, Michael Eugene
1998-09-01
Instrumentation and analytical techniques were developed to measure isotope abundances from nanograms of sulfur and boron. Sulfur isotope compositions were determined employing continuous flow isotope ratio mass spectroscopy (CF-IRMS) procedures and AsS+ thermal ionization mass spectrometry techniques (AsS+-TIMS). Boron isotope abundances were determined by BO2/sp--TIMS. CF-IRMS measurements realized δ34S values from 10 μg sulfur with precisions of ±0.3/perthous. To extend sulfur isotope measurements to much smaller samples, a TIMS procedure was developed to measure 75As32S+ and 75As34S+ at masses 108 and 109 from 200 ng S on a Finnigan MAT 262 with an ion counter. This is possibly the smallest amount of sulfur which has been successfully analyzed isotopically. The internal precision of 32S/34S ratios measured by AsS+-TIMS was better than ±0.15 percent. δ34S-values calculated relative to the measured 32S/34S value of an IAEA AG2S standard (S-1) agreed with those determined by CF-IRMS to within ±3/perthous. The increasing sensitivity of S-isotope analyses permits hiterto impossible investigations e.g. sulfur in tree rings and ice cores. Boron isotope abundances were measured as BO2/sp- from 50 ng B using an older thermal ionization mass spectrometer which had been extensively upgraded including the addition of computer control electronics, sensitive ion current amplification and fiber optic data bus. The internal precisions of the measured 11B/10B ratios were ±0.15 percent and the precisions of δ11B values calculated relative to the accepted international standard (SRM-951) were ±3/perthous. Two applications of boron isotope abundance variations were initiated (1) ground waters of Northern Alberta and (2) coffee beans in different regions of the world. In the first it was demonstrated that boron isotopes could be used to trace boron released during steam injection of oil sands into the surrounding environment. Data from the second study suggest that boron
C/N Ratio Drives Soil Actinobacterial Cellobiohydrolase Gene Diversity
Prendergast-Miller, Miranda T.; Poonpatana, Pabhon; Farrell, Mark; Bissett, Andrew; Macdonald, Lynne M.; Toscas, Peter; Richardson, Alan E.; Thrall, Peter H.
2015-01-01
Cellulose accounts for approximately half of photosynthesis-fixed carbon; however, the ecology of its degradation in soil is still relatively poorly understood. The role of actinobacteria in cellulose degradation has not been extensively investigated despite their abundance in soil and known cellulose degradation capability. Here, the diversity and abundance of the actinobacterial glycoside hydrolase family 48 (cellobiohydrolase) gene in soils from three paired pasture-woodland sites were determined by using terminal restriction fragment length polymorphism (T-RFLP) analysis and clone libraries with gene-specific primers. For comparison, the diversity and abundance of general bacteria and fungi were also assessed. Phylogenetic analysis of the nucleotide sequences of 80 clones revealed significant new diversity of actinobacterial GH48 genes, and analysis of translated protein sequences showed that these enzymes are likely to represent functional cellobiohydrolases. The soil C/N ratio was the primary environmental driver of GH48 community compositions across sites and land uses, demonstrating the importance of substrate quality in their ecology. Furthermore, mid-infrared (MIR) spectrometry-predicted humic organic carbon was distinctly more important to GH48 diversity than to total bacterial and fungal diversity. This suggests a link between the actinobacterial GH48 community and soil organic carbon dynamics and highlights the potential importance of actinobacteria in the terrestrial carbon cycle. PMID:25710367
Freeman, Christopher J; Thacker, Robert W; Baker, David M; Fogel, Marilyn L
2013-06-01
By forming symbiotic interactions with microbes, many animals and plants gain access to the products of novel metabolic pathways. We investigated the transfer of symbiont-derived carbon and nitrogen to the sponges Aplysina cauliformis, Aplysina fulva, Chondrilla caribensis, Neopetrosia subtriangularis and Xestospongia bocatorensis, all of which host abundant microbial populations, and Niphates erecta, which hosts a sparse symbiont community. We incubated sponges in light and dark bottles containing seawater spiked with (13)C- and (15)N-enriched inorganic compounds and then measured (13)C and (15)N enrichment in the microbial (nutrient assimilation) and sponge (nutrient transfer) fractions. Surprisingly, although most sponges hosting abundant microbial communities were more enriched in (13)C than N. erecta, only N. subtriangularis was more enriched in (15)N than N. erecta. Although photosymbiont abundance varied substantially across species, (13)C and (15)N enrichment was not significantly correlated with photosymbiont abundance. Enrichment was significantly correlated with the ratio of gross productivity to respiration (P:R), which varied across host species and symbiont phylotype. Because irradiance impacts P:R ratios, we also incubated A. cauliformis in (13)C-enriched seawater under different irradiances to determine whether symbiont carbon fixation and transfer are dependent on irradiance. Carbon fixation and transfer to the sponge host occurred in all treatments, but was greatest at higher irradiances and was significantly correlated with P:R ratios. Taken together, these results demonstrate that nutrient transfer from microbial symbionts to host sponges is influenced more by host-symbiont identities and P:R ratios than by symbiont abundance.
Relation between self-organized criticality and grain aspect ratio in granular piles
NASA Astrophysics Data System (ADS)
Denisov, D. V.; Villanueva, Y. Y.; Lőrincz, K. A.; May, S.; Wijngaarden, R. J.
2012-05-01
We investigate experimentally whether self-organized criticality (SOC) occurs in granular piles composed of different grains, namely, rice, lentils, quinoa, and mung beans. These four grains were selected to have different aspect ratios, from oblong to oblate. As a function of aspect ratio, we determined the growth (β) and roughness (α) exponents, the avalanche fractal dimension (D), the avalanche size distribution exponent (τ), the critical angle (γ), and its fluctuation. At superficial inspection, three types of grains seem to have power-law-distributed avalanches with a well-defined τ. However, only rice is truly SOC if we take three criteria into account: a power-law-shaped avalanche size distribution, finite size scaling, and a universal scaling relation relating characteristic exponents. We study SOC as a spatiotemporal fractal; in particular, we study the spatial structure of criticality from local observation of the slope angle. From the fluctuation of the slope angle we conclude that greater fluctuation (and thus bigger avalanches) happen in piles consisting of grains with larger aspect ratio.
Gas-phase abundances of refractory elements in planetary nebulae - A hot-wind model
DOE Office of Scientific and Technical Information (OSTI.GOV)
Shields, G.A.
Planetary nebulae (PN) characteristically show large gas-phase depletions of some refractory elements, with Fe/H and Ca/H concentration ratios approximately equal to -1.5. In contrast, the gas-phase abundance of carbon is large, with a C/H concentration ratio greater than approximately +0.3. This pattern is difficult to understand in terms of grain formation and destruction during PN formation. However, these abundances are consistent with a model (Kwok, Purton, and FitzGerald, 1978) in which the PN shell consists of material expelled as a wind during the red-giant phase and subsequently compressed and accelerated by the impact of a hot stellar wind from themore » central star.« less
NASA Astrophysics Data System (ADS)
Feltzing, S.; Eriksson, K.; Kleyna, J.; Wilkinson, M. I.
2009-12-01
Aims. We establish the mean metallicity from high-resolution spectroscopy for the recently found dwarf spheroidal galaxy Boötes I and test whether it is a common feature for ultra-faint dwarf spheroidal galaxies to show signs of inhomogeneous chemical evolution (e.g. as found in the Hercules dwarf spheroidal galaxy). Methods: We analyse high-resolution, moderate signal-to-noise spectra for seven red giant stars in the Boötes I dSph galaxy using standard abundance analysis techniques. In particular, we assume local thermodynamic equilibrium and employ spherical model atmospheres and codes that take the sphericity of the star into account when calculating the elemental abundances. Results: We confirm previous determinations of the mean metallicity of the Boötes I dwarf spheroidal galaxy to be -2.3 dex. Whilst five stars are clustered around this metallicity, one is significantly more metal-poor, at -2.9 dex, and one is more metal-rich at, -1.9 dex. Additionally, we find that one of the stars, Boo-127, shows an atypically high [Mg/Ca] ratio, indicative of stochastic enrichment processes within the dSph galaxy. Similar results have previously only been found in the Hercules and Draco dSph galaxies and appear, so far, to be unique to this type of galaxy. The data presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation.
Bernath-Plaisted, Jacy; Nenninger, Heather; Koper, Nicola
2017-07-01
The rapid expansion of oil and natural gas development across the Northern Great Plains has contributed to habitat fragmentation, which may facilitate brood parasitism of ground-nesting grassland songbird nests by brown-headed cowbirds ( Molothrus ater ), an obligate brood parasite, through the introduction of perches and anthropogenic edges. We tested this hypothesis by measuring brown-headed cowbird relative abundance and brood parasitism rates of Savannah sparrow ( Passerculus sandwichensis ) nests in relation to the presence of infrastructure features and proximity to potential perches and edge habitat. The presence of oil and natural gas infrastructure increased brown-headed cowbird relative abundance by a magnitude of four times, which resulted in four times greater brood parasitism rates at infrastructure sites. While the presence of infrastructure and the proximity to roads were influential in predicting brood parasitism rates, the proximity of perch sites was not. This suggests that brood parasitism associated with oil and natural gas infrastructure may result in additional pressures that reduce productivity of this declining grassland songbird.
Kasimanickam, R K; Kasimanickam, V R; Arangasamy, A; Kastelic, J P
2017-02-01
Mammalian sperm are exposed to a natural hypoosmotic environment during male-to-female reproductive tract transition; although this activates sperm motility in vivo, excessive swelling can harm sperm structure and function. Aquaporins (AQPs) is a family of membrane-channel proteins implicated in sperm osmoregulation. The objective was to determine associations among relative sperm volume shift, hypoosmotic swelling test (HOST), sperm aquaporin (AQP) 7 mRNA abundances, and sire conception rate (SCR; fertility estimate) in Holstein bulls at a commercial artificial insemination center. Three or four sires for each full point SCR score from -4 to +4 were included. Each SCR estimate for study bulls (N = 30) was based on > 500 services (mean ± SEM) of 725 ± 13 services/sire). Sperm from a single collection day (two ejaculates) from these commercial Holstein bulls were used. Relative mRNA expression of AQP7 in sperm was determined by polymerase chain reaction. Mean relative sperm volume shift and percentage of sperm reacted in a HOST (% HOST) were determined (400 sperm per bull) after incubating in isoosmotic (300 mOsm/kg) and hypoosmotic (100 mOsm/kg) solutions for 30 min. There was no correlation between %HOST and SCR (r = 0.28 P > 0.1). However, there was a positive correlation between relative sperm volume shift and SCR (r = 0.65, P < 0.05). Furthermore, AQP7 mRNA abundance was positively correlated to both relative volume shift (r = 0.73; P < 0.05) and to SCR (r = 0.67; P < 0.05). The mRNA expressions of AQP7 and relative sperm volume shift differed (P < 0.05) among low- (<2 SCR), average- (-2 to +2) and high- (>2) fertility sire groups. In conclusion, bulls with higher SCR had significantly greater AQP7 mRNA abundance in frozen-thawed sperm. This plausibly contributed to greater regulation of sperm volume shift, which apparently conferred protection from detrimental swelling and impaired functions. Copyright © 2016 Elsevier Inc. All
Galaiduk, Ronen; Radford, Ben T; Harvey, Euan S
2018-06-21
Many fishes undergo ontogenetic habitat shifts to meet their energy and resource needs as they grow. Habitat resource partitioning and patterns of habitat connectivity between conspecific fishes at different life-history stages is a significant knowledge gap. Species distribution models were used to examine patterns in the relative abundance, individual biomass estimates and environmental niche associations of different life stages of three iconic West Australian fishes. Continuous predictive maps describing the spatial distribution of abundance and individual biomass of the study species were created as well predictive hotspot maps that identify possible areas for aggregation of individuals of similar life stages of multiple species (i.e. spawning grounds, fisheries refugia or nursery areas). The models and maps indicate that processes driving the abundance patterns could be different from the body size associated demographic processes throughout an individual's life cycle. Incorporating life-history in the spatially explicit management plans can ensure that critical habitat of the vulnerable stages (e.g. juvenile fish, spawning stock) is included within proposed protected areas and can enhance connectivity between various functional areas (e.g. nursery areas and adult populations) which, in turn, can improve the abundance of targeted species as well as other fish species relying on healthy ecosystem functioning.
Mineral abundances of comet 17P/Holmes derived from the mid-infrared spectrum
NASA Astrophysics Data System (ADS)
Shinnaka, Yoshiharu; Yamaguchi, MItsuru; Ootsubo, Takafumi; Kawakita, Hideyo; Sakon, Itsuki; Honda, Mitsuhiko; Watanabe, Jun-ichi
2017-10-01
Dust grains of crystalline silicate, which is rarely presented in an interstellar space, were found in cometary nuclei (Messenger et al. 1996, LPI, 27, 867; Wooden et al. 1999, ApJ, 517, 1058, references therein). It is thought that these crystalline silicates had formed by annealing or condensations of amorphous grains near the Sun in the solar nebula, and incorporated into a cometary nucleus in a cold region (farther than formation regions of the crystalline silicates) by radial transportation in the solar nebula. It is considered that transportation mechanisms to outside of the solar nebula were turbulent and/or X-wind. An abundance of the crystalline dust grains was therefore expected to be smaller as far from the Sun (Gail, 2001, A&A, 378, 192; Bockelée-Morvan et al. 2002, A&A, 384, 1107). Namely, the abundance ratio of the crystalline silicate in cometary dust grains relates a degree of mass transportation and a distance from the Sun when cometary nucleus formed in the Solar nebula. The mass ratio of crystalline silicates of dust grains is determined from by Si-O stretching vibrational bands of silicate grains around 10 μm using difference of spectral band features between crystalline and amorphous grains. We present the crystalline-to-amorphous mass ratio of silicate grains in the comet 17P/Holmes by using the thermal emission mode of the dust grains (Ootsubo et al. 2007, P&SS, 55, 1044) applied to the mid-infrared spectra of the comet. These spectra were taken by the COMICS mounted on the Subaru Telescope on 2007 October 25, 26, 27 and 28 immediately after the great outburst of the comet (started on October 23). We discuss about formation conditions of the nucleus of the comet based on the derived mass ratio of silicate grains of the comet.
Nucleosynthesis: Stellar and Solar Abundances and Atomic Data
NASA Technical Reports Server (NTRS)
Cowan, John J.; Lawler, James E.; Sneden, Christopher; DenHartog, E. A.; Collier, Jason; Dodge, Homer L.
2006-01-01
Abundance observations indicate the presence of often surprisingly large amounts of neutron capture (i.e., s- and r-process) elements in old Galactic halo and globular cluster stars. These observations provide insight into the nature of the earliest generations of stars in the Galaxy the progenitors of the halo stars responsible for neutron-capture synthesis. Comparisons of abundance trends can be used to understand the chemical evolution of the Galaxy and the nature of heavy element nucleosynthesis. In addition age determinations, based upon long-lived radioactive nuclei abundances, can now be obtained. These stellar abundance determinations depend critically upon atomic data. Improved laboratory transition probabilities have been recently obtained for a number of elements. These new gf values have been used to greatly refine the abundances of neutron-capture elemental abundances in the solar photosphere and in very metal-poor Galactic halo stars. The newly determined stellar abundances are surprisingly consistent with a (relative) Solar System r-process pattern, and are also consistent with abundance predictions expected from such neutron-capture nucleosynthesis.
Abundance estimation and conservation biology
Nichols, J.D.; MacKenzie, D.I.
2004-01-01
should be focused on relationships between demographic processes such as survival and recruitment, the two quantities responsible for changes in abundance, rather than simply on the magnitudes of these quantities. They describe a type of Jolly–Seber capture–recapture model that permits inference about the underlying relationship between per capita recruitment rates and survival rates (Link & Barker, this volume). Implementation used Bayesian Markov Chain Monte Carlo methods and appeared to work well, yielding inferences about the relationship between recruitment and survival that were robust to selection of prior distribution. We believe that readers will find their arguments compelling, and we expect to see increased use of hierarchical modeling approaches in capture–recapture and related fields. Otto (presentation without paper) also recommended use of hierarchical models in analysis of multiple data sources dealing with population dynamics of North American mallards. He integrated survival inferences from ringing data, abundance information from aerial survey data, and recruitment information based on age ratios from a harvest survey. He used a Leslie matrix population projection model as an integrating framework and obtained estimates of breeding population size using all data.Otto’s approach also permitted inference about biases in estimated quantities. As with the work of Link & Barker (2004), we find Otto’s recommendation to use hierarchical models to integrate data from multiple sources to be very compelling. Alisauskas et al. (2004) report results of an analysis of capture–recapture data for a askatchewan population of white–winged scoters. They used the approach of Pradel (1996) to estimate population growth rate (See the PDF) directly. Estimates for 1975–1985 were quite low, but estimates for the recent period, 2000–2003,increased to values > 1. Parameter estimates for seniority, survival and per capita recruitment (Pradel, 1996) led to the
Jiang, Zhou; Li, Ping; Jiang, Dawei; Wu, Geng; Dong, Hailiang; Wang, Yanhong; Li, Bing; Wang, Yanxin; Guo, Qinghai
2014-01-01
A total of 12 samples were collected from the Tengchong geothermal areas of Yunnan, China, with the goal to assess the arsenite (AsIII) oxidation potential of the extant microbial communities as inferred by the abundance and diversity of the AsIII oxidase large subunit gene aioA relative to geochemical context. Arsenic concentrations were higher (on average 251.68 μg/L) in neutral or alkaline springs than in acidic springs (on average 30.88 μg/L). aioA abundance ranged from 1.63 × 10(1) to 7.08 × 10(3) per ng of DNA and positively correlated with sulfide and the ratios of arsenate (AsV):total dissolved arsenic (AsTot). Based on qPCR estimates of bacterial and archaeal 16S rRNA gene abundance, aioA-harboring organisms comprised as much as ~15% of the total community. Phylogenetically, the major aioA sequences (270 total) in the acidic hot springs (pH 3.3-4.4) were affiliated with Aquificales and Rhizobiales, while those in neutral or alkaline springs (pH 6.6-9.1) were inferred to be primarily bacteria related to Thermales and Burkholderiales. Interestingly, aioA abundance at one site greatly exceeded bacterial 16S rRNA gene abundance, suggesting these aioA genes were archaeal even though phylogenetically these aioA sequences were most similar to the Aquificales. In summary, this study described novel aioA sequences in geothermal features geographically far removed from those in the heavily studied Yellowstone geothermal complex.
Bond, Mark E.; Babcock, Elizabeth A.; Pikitch, Ellen K.; Abercrombie, Debra L.; Lamb, Norlan F.; Chapman, Demian D.
2012-01-01
Carcharhinid sharks can make up a large fraction of the top predators inhabiting tropical marine ecosystems and have declined in many regions due to intense fishing pressure. There is some support for the hypothesis that carcharhinid species that complete their life-cycle within coral reef ecosystems, hereafter referred to as “reef sharks”, are more abundant inside no-take marine reserves due to a reduction in fishing pressure (i.e., they benefit from marine reserves). Key predictions of this hypothesis are that (a) individual reef sharks exhibit high site-fidelity to these protected areas and (b) their relative abundance will generally be higher in these areas compared to fished reefs. To test this hypothesis for the first time in Caribbean coral reef ecosystems we combined acoustic monitoring and baited remote underwater video (BRUV) surveys to measure reef shark site-fidelity and relative abundance, respectively. We focused on the Caribbean reef shark (Carcharhinus perezi), the most common reef shark in the Western Atlantic, at Glover's Reef Marine Reserve (GRMR), Belize. Acoustically tagged sharks (N = 34) were detected throughout the year at this location and exhibited strong site-fidelity. Shark presence or absence on 200 BRUVs deployed at GRMR and three other sites (another reserve site and two fished reefs) showed that the factor “marine reserve” had a significant positive effect on reef shark presence. We rejected environmental factors or site-environment interactions as predominant drivers of this pattern. These results are consistent with the hypothesis that marine reserves can benefit reef shark populations and we suggest new hypotheses to determine the underlying mechanism(s) involved: reduced fishing mortality or enhanced prey availability. PMID:22412965
BOND: A quantum of solace for nebular abundance determinations
NASA Astrophysics Data System (ADS)
Vale Asari, N.; Stasińska, G.; Morisset, C.; Cid Fernandes, R.
2017-11-01
The abundances of chemical elements other than hydrogen and helium in a galaxy are the fossil record of its star formation history. Empirical relations such as mass-metallicity relation are thus seen as guides for studies on the history and chemical evolution of galaxies. Those relations usually rely on nebular metallicities measured with strong-line methods, which assume that H II regions are a one- (or at most two-) parameter family where the oxygen abundance is the driving quantity. Nature is however much more complex than that, and metallicities from strong lines may be strongly biased. We have developed the method BOND (Bayesian Oxygen and Nitrogen abundance Determinations) to simultaneously derive oxygen and nitrogen abundances in giant H II regions by comparing strong and semi-strong observed emission lines to a carefully-defined, finely-meshed grid of photoionization models. Our code and results are public and available at http://bond.ufsc.br.
Adverse moisture events predict seasonal abundance of Lyme disease vector ticks (Ixodes scapularis)
Berger, Kathryn A.; Ginsberg, Howard S.; Dugas, Katherine D.; Hamel, Lutz H.; Mather, Thomas N.
2014-01-01
Background: Lyme borreliosis (LB) is the most commonly reported vector-borne disease in north temperate regions worldwide, affecting an estimated 300,000 people annually in the United States alone. The incidence of LB is correlated with human exposure to its vector, the blacklegged tick (Ixodes scapularis). To date, attempts to model tick encounter risk based on environmental parameters have been equivocal. Previous studies have not considered (1) the differences between relative humidity (RH) in leaf litter and at weather stations, (2) the RH threshold that affects nymphal blacklegged tick survival, and (3) the time required below the threshold to induce mortality. We clarify the association between environmental moisture and tick survival by presenting a significant relationship between the total number of tick adverse moisture events (TAMEs - calculated as microclimatic periods below a RH threshold) and tick abundance each year.Methods: We used a 14-year continuous statewide tick surveillance database and corresponding weather data from Rhode Island (RI), USA, to assess the effects of TAMEs on nymphal populations of I. scapularis. These TAMEs were defined as extended periods of time (>8 h below 82% RH in leaf litter). We fit a sigmoid curve comparing weather station data to those collected by loggers placed in tick habitats to estimate RH experienced by nymphal ticks, and compiled the number of historical TAMEs during the 14-year record.Results: The total number of TAMEs in June of each year was negatively related to total seasonal nymphal tick densities, suggesting that sub-threshold humidity episodes >8 h in duration naturally lowered nymphal blacklegged tick abundance. Furthermore, TAMEs were positively related to the ratio of tick abundance early in the season when compared to late season, suggesting that lower than average tick abundance for a given year resulted from tick mortality and not from other factors.Conclusions: Our results clarify the mechanism
Niobium in R And (S6, 6e) and HR 1105 (S5, 3). [S star abundance
NASA Technical Reports Server (NTRS)
Davis, D. N.
1985-01-01
Lines of the first multiplet of niobium are strong in R And and HR 1105. These lines are also present in other S stars: HR 8714, R Cam, V Cnc, R CMi, and T Sgr. They are also visible in the M stars, Beta-Peg and Mu-UMa. An approximation to the abundance ratio, Nb/Fe, has been deduced from pairs of lines having nearly equal intensity. In R And, the ratio is about 200 times the solar value. It is hoped that good plates will soon be obtained for the near infrared region, so that the significant Nb/Rb abundance ratio may be determined.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Palmerini, S.; Busso, M.; Maiorca, E.
2011-11-01
We reanalyze the problem of Li abundances in red giants of nearly solar metallicity. After outlining the problems affecting our knowledge of the Li content in low-mass stars (M {<=} 3 M{sub sun}), we discuss deep-mixing models for the red giant branch stages suitable to account for the observed trends and for the correlated variations of the carbon isotope ratio; we find that Li destruction in these phases is limited to masses below about 2.3 M{sub sun}. Subsequently, we concentrate on the final stages of evolution for both O-rich and C-rich asymptotic giant branch (AGB) stars. Here, the constraints onmore » extra-mixing phenomena previously derived from heavier nuclei (from C to Al), coupled to recent updates in stellar structure models (including both the input physics and the set of reaction rates used), are suitable to account for the observations of Li abundances below A(Li) {identical_to} log {epsilon}(Li) {approx_equal} 1.5 (and sometimes more). Also, their relations with other nucleosynthesis signatures of AGB phases (like the abundance of F, and the C/O and {sup 12}C/{sup 13}C ratios) can be explained. This requires generally moderate efficiencies (M-dot < or approx. 0.3-0.5 x 10{sup -6} M{sub sun} yr{sup -1}) for non-convective mass transport. At such rates, slow extra mixing does not remarkably modify Li abundances in early AGB phases; on the other hand, faster mixing encounters a physical limit in destroying Li, set by the mixing velocity. Beyond this limit, Li starts to be produced; therefore, its destruction on the AGB is modest. Li is then significantly produced by the third dredge up. We also show that effective circulation episodes, while not destroying Li, would easily bring the {sup 12}C/{sup 13}C ratios to equilibrium, contrary to the evidence in most AGB stars, and would burn F beyond the limits shown by C(N) giants. Hence, we do not confirm the common idea that efficient extra mixing drastically reduces the Li content of C stars with respect
Effects of Cluster Environment on Chemical Abundances in Virgo Cluster Spirals
NASA Astrophysics Data System (ADS)
Kennicutt, R. C.; Skillman, E. D.; Shields, G. A.; Zaritsky, D.
1995-12-01
We have obtained new chemical abundance measurements of HII regions in Virgo cluster spiral galaxies, in order to test whether the cluster environment has significantly influenced the gas-phase abundances and chemical evolution of spiral disks. The sample of 9 Virgo spirals covers a narrow range of morphological type (Sbc - Sc) but shows broad ranges in HI deficiencies and radii in the cluster. This allows us to compare the Virgo sample as a whole to field spirals, using a large sample from Zaritsky, Kennicutt, & Huchra, and to test for systematic trends with HI content and location within the cluster. The Virgo spirals show a wide dispersion in mean disk abundances and abundance gradients. Strongly HI deficient spirals closest to the cluster core show anomalously high oxygen abundances (by 0.3 to 0.5 dex), while outlying spirals with normal HI content show abundances similar to those of field spirals. The most HI depleted spirals also show weaker abundance gradients on average, but the formal significance of this trend is marginal. We find a strong correlation between mean abundance and HI/optical diameter ratio that is quite distinct from the behavior seen in field galaxies. This suggests that dynamical processes associated with the cluster environment are more important than cluster membership in determining the evolution of chemical abundances and stellar populations in spiral galaxies. Simple chemical evolution models are calculated to predict the magnitude of the abundance enhancement expected if ram-pressure stripping or curtailment of infall is responsible for the gas deficiencies. The increased abundances of the spirals in the cluster core may have significant effects on their use as cosmological standard candles.
Terrestrial salamander abundance on reclaimed mountaintop removal mines
Wood, Petra Bohall; Williams, Jennifer M.
2013-01-01
Mountaintop removal mining, a large-scale disturbance affecting vegetation, soil structure, and topography, converts landscapes from mature forests to extensive grassland and shrubland habitats. We sampled salamanders using drift-fence arrays and coverboard transects on and near mountaintop removal mines in southern West Virginia, USA, during 2000–2002. We compared terrestrial salamander relative abundance and species richness of un-mined, intact forest with habitats on reclaimed mountaintop removal mines (reclaimed grassland, reclaimed shrubland, and fragmented forest). Salamanders within forests increased in relative abundance with increasing distance from reclaimed mine edge. Reclaimed grassland and shrubland habitats had lower relative abundance and species richness than forests. Characteristics of reclaimed habitats that likely contributed to lower salamander abundance included poor soils (dry, compacted, little organic matter, high rock content), reduced vertical structure of vegetation and little tree cover, and low litter and woody debris cover. Past research has shown that salamander populations reduced by clearcutting may rebound in 15–24 years. Time since disturbance was 7–28 years in reclaimed habitats on our study areas and salamander populations had not reached levels found in adjacent mature forests.
DETAILED ABUNDANCES OF THE SOLAR TWINS 16 CYGNI A AND B: CONSTRAINING PLANET FORMATION MODELS
DOE Office of Scientific and Technical Information (OSTI.GOV)
Schuler, Simon C.; Cunha, Katia; Smith, Verne V.
2011-08-20
Results of a detailed abundance analysis of the solar twins 16 Cyg A and 16 Cyg B based on high-resolution, high signal-to-noise ratio echelle spectroscopy are presented. 16 Cyg B is known to host a giant planet while no planets have yet been detected around 16 Cyg A. Stellar parameters are derived directly from our high-quality spectra, and the stars are found to be physically similar, with {Delta}T{sub eff} = +43 K, {Delta}log g = -0.02 dex, and {Delta}{xi} = +0.10 km s{sup -1} (in the sense of A - B), consistent with previous findings. Abundances of 15 elements aremore » derived and are found to be indistinguishable between the two stars. The abundances of each element differ by {<=}0.026 dex, and the mean difference is +0.003 {+-} 0.015 ({sigma}) dex. Aside from Li, which has been previously shown to be depleted by a factor of at least 4.5 in 16 Cyg B relative to 16 Cyg A, the two stars appear to be chemically identical. The abundances of each star demonstrate a positive correlation with the condensation temperature of the elements (T{sub c}); the slopes of the trends are also indistinguishable. In accordance with recent suggestions, the positive slopes of the [m/H]-T{sub c} relations may imply that terrestrial planets have not formed around either 16 Cyg A or 16 Cyg B. The physical characteristics of the 16 Cyg system are discussed in terms of planet formation models, and plausible mechanisms that can account for the lack of detected planets around 16 Cyg A, the disparate Li abundances of 16 Cyg A and B, and the eccentricity of the planet 16 Cyg B b are suggested.« less
Synthetic isotope mixtures for the calibration of isotope amount ratio measurements of carbon
NASA Astrophysics Data System (ADS)
Russe, K.; Valkiers, S.; Taylor, P. D. P.
2004-07-01
Synthetic isotope mixtures for the calibration of carbon isotope amount ratio measurements have been prepared by mixing carbon tetrafluoride highly enriched in 13C with carbon tetrafluoride depleted in 13C. Mixing procedures based on volumetry and gravimetry are described. The mixtures served as primary measurement standards for the calibration of isotope amount ratio measurements of the Isotopic Reference Materials PEF1, NBS22 and USGS24. Thus SI-traceable measurements of absolute carbon isotope amount ratios have been performed for the first time without any hypothesis needed for a correction of oxygen isotope abundances, such as is the case for measurements on carbon dioxide. As a result, "absolute" carbon isotope amount ratios determined via carbon tetrafluoride have smaller uncertainties than those published for carbon dioxide. From the measurements of the Reference Materials concerned, the absolute carbon isotope amount ratio of Vienna Pee Dee Belemnite (VPDB)--the hypothetical material upon which the scale for relative carbon isotope ratio measurements is based--was calculated to be R13(VPDB) = (11 101 +/- 16) × 10-6.
Samant, Suvidha; Huo, Tian; Dawson, Jeffrey O; Hahn, Dittmar
2016-02-01
Quantitative polymerase chain reaction (qPCR) was used to assess the abundance and relative distribution of host infection groups of the root-nodule forming, nitrogen-fixing actinomycete Frankia in four soils with similar physicochemical characteristics, two of which were vegetated with a host plant, Alnus glutinosa, and two with a non-host plant, Betula nigra. Analyses of DAPI-stained cells at three locations, i.e., at a distance of less than 1 m (near stem), 2.5 m (middle crown), and 3-5 m (crown edge) from the stems of both tree species revealed no statistically significant differences in abundance. Frankiae generally accounted for 0.01 to 0.04 % of these cells, with values between 4 and 36 × 10(5) cells (g soil)(-1). In three out of four soils, abundance of frankiae was significantly higher at locations "near stem" and/or "middle crown" compared to "crown edge," while numbers at these locations were not different in the fourth soil. Frankiae of the Alnus host infection group were dominant in all samples accounting for about 75 % and more of the cells, with no obvious differences with distance to stem. In three of the soils, all of these cells were represented by strain Ag45/Mut15. In the fourth soil that was vegetated with older A. glutinosa trees, about half of these cells belonged to a different subgroup represented by strain ArI3. In all soils, the remaining cells belonged to the Elaeagnus host infection group represented by strain EAN1pec. Casuarina-infective frankiae were not found. Abundance and relative distribution of Frankia host infection groups were similar in soils under the host plant A. glutinosa and the non-host plant B. nigra. Results did thus not reveal any specific effects of plant species on soil Frankia populations.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Hema, B. P.; Pandey, Gajendra; Lambert, David L., E-mail: hema@iiap.res.in, E-mail: pandey@iiap.res.in, E-mail: dll@astro.as.utexas.edu
2012-03-10
Observed spectra of R Coronae Borealis (RCB) and hydrogen-deficient carbon (HdC) stars are analyzed by synthesizing the C{sub 2} Swan bands (1, 0), (0, 0), and (0, 1) using our detailed line list and the Uppsala model atmospheres. The (0, 1) and (0, 0) C{sub 2} bands are used to derive the {sup 12}C abundance, and the (1, 0) {sup 12}C{sup 13}C band to determine the {sup 12}C/{sup 13}C ratios. The carbon abundance derived from the C{sub 2} Swan bands is about the same for the adopted models constructed with different carbon abundances over the range 8.5 (C/He = 0.1%)more » to 10.5 (C/He = 10%). Carbon abundances derived from C I lines are about a factor of four lower than the carbon abundance of the adopted model atmosphere over the same C/He interval, as reported by Asplund et al., who dubbed the mismatch between adopted and derived C abundance as the 'carbon problem'. In principle, the carbon abundances obtained from C{sub 2} Swan bands and that assumed for the model atmosphere can be equated for a particular choice of C/He that varies from star to star. Then, the carbon problem for C{sub 2} bands is eliminated. However, such C/He ratios are in general less than those of the extreme helium stars, the seemingly natural relatives to the RCB and HdC stars. A more likely solution to the C{sub 2} carbon problem may lie in a modification of the model atmosphere's temperature structure. The derived carbon abundances and the {sup 12}C/{sup 13}C ratios are discussed in light of the double degenerate and the final flash scenarios.« less
Abundances, Ionization States, Temperatures, and FIP in Solar Energetic Particles
NASA Astrophysics Data System (ADS)
Reames, Donald V.
2018-04-01
The relative abundances of chemical elements and isotopes have been our most effective tool in identifying and understanding the physical processes that control populations of energetic particles. The early surprise in solar energetic particles (SEPs) was 1000-fold enhancements in {}3He/{}4He from resonant wave-particle interactions in the small "impulsive" SEP events that emit electron beams that produce type III radio bursts. Further studies found enhancements in Fe/O, then extreme enhancements in element abundances that increase with mass-to-charge ratio A/Q, rising by a factor of 1000 from He to Au or Pb arising in magnetic reconnection regions on open field lines in solar jets. In contrast, in the largest SEP events, the "gradual" events, acceleration occurs at shock waves driven out from the Sun by fast, wide coronal mass ejections (CMEs). Averaging many events provides a measure of solar coronal abundances, but A/Q-dependent scattering during transport causes variations with time; thus if Fe scatters less than O, Fe/O is enhanced early and depleted later. To complicate matters, shock waves often reaccelerate impulsive suprathermal ions left over or trapped above active regions that have spawned many impulsive events. Direct measurements of ionization states Q show coronal temperatures of 1-2 MK for most gradual events, but impulsive events often show stripping by matter traversal after acceleration. Direct measurements of Q are difficult and often unavailable. Since both impulsive and gradual SEP events have abundance enhancements that vary as powers of A/Q, we can use abundances to deduce the probable Q-values and the source plasma temperatures during acceleration, ≈3 MK for impulsive SEPs. This new technique also allows multiple spacecraft to measure temperature variations across the face of a shock wave, measurements otherwise unavailable and provides a new understanding of abundance variations in the element He. Comparing coronal abundances from SEPs
Influence of culture medium composition on relative mRNA abundances in domestic cat embryos.
Hribal, R; Jewgenow, K; Braun, B C; Comizzoli, P
2013-04-01
Different culture conditions have been used to produce domestic cat embryos. As part of the in vitro procedures, the medium composition significantly affects the quality of the embryo development also. Quality assessments based on cleavage kinetics and blastomere symmetry are useful, but embryos also can differ in their relative gene expression patterns despite similar morphological characteristics. The aim of this study was to compare cat embryos produced with two different in vitro culture systems routinely used in two different laboratories [Smithsonian Conservation Biology Institute, Washington D.C., USA (SCBI) and Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany (IZW)]. Specifically, relative mRNA expression patterns of critical genes for pre-implantation embryo development were assessed in both conditions. Embryos were produced in parallel in both culture systems by IVF using frozen-thawed ejaculated semen in the United States and fresh epididymal sperm in Germany. Success of embryo development in vitro was recorded as well as relative mRNA abundances [DNA methyltransferases 1 and 3A (DNMT1, DNMT3A), gap junction protein alpha 1 (GJA1), octamer-binding transcription factor 4 [OCT4], insulin-like growth factors 1 and 2 receptors (IGF1R, IGF2R), beta-actin (ACTB)] in pools of days 4-5 morulae by semi-quantitative RT-PCR assay. Percentages of cleaved embryos were similar (p > 0.05) between both culture systems, regardless of the location. OCT4 mRNA abundance was higher (p < 0.05) in embryos derived in the SCBI culture system compared with those from the IZW system when epididymal sperm was used for IVF. No clear correlation between the expression pattern and the culture system could be found for all other genes. It is suggested that OCT4 expression might be affected by the media composition in some conditions and can be the indicator of a better embryo quality. © 2012 Blackwell Verlag GmbH.
Towards a framework for testing general relativity with extreme-mass-ratio-inspiral observations
NASA Astrophysics Data System (ADS)
Chua, A. J. K.; Hee, S.; Handley, W. J.; Higson, E.; Moore, C. J.; Gair, J. R.; Hobson, M. P.; Lasenby, A. N.
2018-07-01
Extreme-mass-ratio-inspiral observations from future space-based gravitational-wave detectors such as LISA will enable strong-field tests of general relativity with unprecedented precision, but at prohibitive computational cost if existing statistical techniques are used. In one such test that is currently employed for LIGO black hole binary mergers, generic deviations from relativity are represented by N deformation parameters in a generalized waveform model; the Bayesian evidence for each of its 2N combinatorial submodels is then combined into a posterior odds ratio for modified gravity over relativity in a null-hypothesis test. We adapt and apply this test to a generalized model for extreme-mass-ratio inspirals constructed on deformed black hole spacetimes, and focus our investigation on how computational efficiency can be increased through an evidence-free method of model selection. This method is akin to the algorithm known as product-space Markov chain Monte Carlo, but uses nested sampling and improved error estimates from a rethreading technique. We perform benchmarking and robustness checks for the method, and find order-of-magnitude computational gains over regular nested sampling in the case of synthetic data generated from the null model.
Towards a framework for testing general relativity with extreme-mass-ratio-inspiral observations
NASA Astrophysics Data System (ADS)
Chua, A. J. K.; Hee, S.; Handley, W. J.; Higson, E.; Moore, C. J.; Gair, J. R.; Hobson, M. P.; Lasenby, A. N.
2018-04-01
Extreme-mass-ratio-inspiral observations from future space-based gravitational-wave detectors such as LISA will enable strong-field tests of general relativity with unprecedented precision, but at prohibitive computational cost if existing statistical techniques are used. In one such test that is currently employed for LIGO black-hole binary mergers, generic deviations from relativity are represented by N deformation parameters in a generalised waveform model; the Bayesian evidence for each of its 2N combinatorial submodels is then combined into a posterior odds ratio for modified gravity over relativity in a null-hypothesis test. We adapt and apply this test to a generalised model for extreme-mass-ratio inspirals constructed on deformed black-hole spacetimes, and focus our investigation on how computational efficiency can be increased through an evidence-free method of model selection. This method is akin to the algorithm known as product-space Markov chain Monte Carlo, but uses nested sampling and improved error estimates from a rethreading technique. We perform benchmarking and robustness checks for the method, and find order-of-magnitude computational gains over regular nested sampling in the case of synthetic data generated from the null model.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Klein, B.; Jura, M.; Zuckerman, B.
2010-02-01
We present Keck/High Resolution Echelle Spectrometer data with model atmosphere analysis of the helium-dominated polluted white dwarf GD 40, in which we measure atmospheric abundances relative to helium of nine elements: H, O, Mg, Si, Ca, Ti, Cr, Mn, and Fe. Apart from hydrogen, whose association with the other contaminants is uncertain, this material most likely accreted from GD 40's circumstellar dust disk whose existence is demonstrated by excess infrared emission. The data are best explained by accretion of rocky planetary material, in which heavy elements are largely contained within oxides, derived from a tidally disrupted minor planet at leastmore » the mass of Juno, and probably as massive as Vesta. The relatively low hydrogen abundance sets an upper limit of 10% water by mass in the inferred parent body, and the relatively high abundances of refractory elements, Ca and Ti, may indicate high-temperature processing. While the overall constitution of the parent body is similar to the bulk Earth being over 85% by mass composed of oxygen, magnesium, silicon, and iron, we find n(Si)/n(Mg) = 0.30 +- 0.11, significantly smaller than the ratio near unity for the bulk Earth, chondrites, the Sun, and nearby stars. This result suggests that differentiation occurred within the parent body.« less
Detailed abundances from integrated-light spectroscopy: Milky Way globular clusters
NASA Astrophysics Data System (ADS)
Larsen, S. S.; Brodie, J. P.; Strader, J.
2017-05-01
Context. Integrated-light spectroscopy at high spectral resolution is rapidly maturing as a powerful way to measure detailed chemical abundances for extragalactic globular clusters (GCs). Aims: We test the performance of our analysis technique for integrated-light spectra by applying it to seven well-studied Galactic GCs that span a wide range of metallicities. Methods: Integrated-light spectra were obtained by scanning the slit of the UVES spectrograph on the ESO Very Large Telescope across the half-light diameters of the clusters. We modelled the spectra using resolved Hubble Space Telescope colour-magnitude diagrams (CMDs), as well as theoretical isochrones, in combination with standard stellar atmosphere and spectral synthesis codes. The abundances of Fe, Na, Mg, Ca, Ti, Cr, and Ba were compared with literature data for individual stars in the clusters. Results: The typical differences between iron abundances derived from our integrated-light spectra and those compiled from the literature are less than 0.1 dex. A larger difference is found for one cluster (NGC 6752), and is most likely caused primarily by stochastic fluctuations in the numbers of bright red giants within the scanned area. As expected, the α-elements (Ca, Ti) are enhanced by about 0.3 dex compared to the Solar-scaled composition, while the [Cr/Fe] ratios are close to Solar. When using up-to-date line lists, our [Mg/Fe] ratios also agree well with literature data. Our [Na/Fe] ratios are, on average, 0.08-0.14 dex lower than average values quoted in the literature, and our [Ba/Fe] ratios may be overestimated by 0.20-0.35 dex at the lowest metallicities. We find that analyses based on theoretical isochrones give very similar results to those based on resolved CMDs. Conclusions: Overall, the agreement between our integrated-light abundance measurements and the literature data is satisfactory. Refinements of the modelling procedure, such as corrections for stellar evolutionary and non-LTE effects
Koch, Robert L; Pahs, Tiffany
2015-04-01
In response to concerns of increasing significance of stink bugs (Hemiptera: Heteroptera: Pentatomidae) in northern states, a survey was conducted over 2 yr in Minnesota to characterize the Pentatomidae associated with field corn, Zea mays L. Halyomorpha halys (Stål), an exotic species, was not detected in this survey, despite continued detection of this species as an invader of human-made structures in Minnesota. Five species of Pentatomidae (four herbivorous; one predatory) were collected from corn. Across years, Euschistus variolarius (Palisot de Beauvois) and Euschistus servus euschistoides (Vollenhoven) had the greatest relative abundances and frequencies of detection. In 2012, the abundance of herbivorous species exceeded 25 nymphs and adults per 100 plants (i.e., an economic threshold) in 0.48% of fields. However, the abundance of herbivorous species did not reach economic levels in any fields sampled in 2013. The frequency of detection of herbivorous species and ratio of nymphs to adults was highest during reproductive growth stages of corn. The predator species, Podisus maculiventris (Say), was detected in 0 to 0.32% of fields. These results provide baseline information on the species composition and abundance of Pentatomidae in Minnesota field corn, which will be necessary for documentation of changes to this fauna as a result of the invasion of H. halys and to determine if some native species continue to increase in abundance in field crops. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
CO abundance variations in the Orion Molecular Cloud
NASA Astrophysics Data System (ADS)
Ripple, F.; Heyer, M. H.; Gutermuth, R.; Snell, R. L.; Brunt, C. M.
2013-05-01
Infrared stellar photometry from the Two Micron All-Sky Survey (2MASS) and spectral line imaging observations of 12CO and 13CO J = 1-0 line emission from the Five College Radio Astronomy Observatory (FCRAO) 14-m telescope are analysed to assess the variation of the CO abundance with physical conditions throughout the Orion A and Orion B molecular clouds. Three distinct Av regimes are identified in which the ratio between the 13CO column density and visual extinction changes corresponding to the photon-dominated envelope, the strongly self-shielded interior, and the cold, dense volumes of the clouds. Within the strongly self-shielded interior of the Orion A cloud, the 13CO abundance varies by 100 per cent with a peak value located near regions of enhanced star formation activity. The effect of CO depletion on to the ice mantles of dust grains is limited to regions with Av > 10 mag and gas temperatures less than ˜20 K as predicted by chemical models that consider thermal evaporation to desorb molecules from grain surfaces. Values of the molecular mass of each cloud are independently derived from the distributions of Av and 13CO column densities with a constant 13CO-to-H2 abundance over various extinction ranges. Within the strongly self-shielded interior of the cloud (Av> 3 mag), 13CO provides a reliable tracer of H2 mass with the exception of the cold, dense volumes where depletion is important. However, owing to its reduced abundance, 13CO does not trace the H2 mass that resides in the extended cloud envelope, which comprises 40-50 per cent of the molecular mass of each cloud. The implied CO luminosity to mass ratios, M/LCO, are 3.2 and 2.9 for Orion A and Orion B, respectively, which are comparable to the value (2.9), derived from γ-ray observations of the Orion region. Our results emphasize the need to consider local conditions when applying CO observations to derive H2 column densities.
Ramey, Andrew M.; Poulson, Rebecca L.; González-Reiche, Ana S.; Wilcox, Benjamin R.; Walther, Patrick; Link, Paul; Carter, Deborah L.; Newsome, George M.; Müller, Maria L.; Berghaus, Roy D.; Perez, Daniel R.; Hall, Jeffrey S.; Stallknecht, David E.
2014-01-01
Seasonal dynamics of influenza A viruses (IAVs) are driven by host density and population immunity. Through an analysis of subtypic data for IAVs isolated from Blue-winged Teal (Anas discors), we present evidence for seasonal patterns in the relative abundance of viral subtypes in spring and summer/autumn.
Abundance of introduced species at home predicts abundance away in herbaceous communities
Firn, Jennifer; Moore, Joslin L.; MacDougall, Andrew S.; Borer, Elizabeth T.; Seabloom, Eric W.; HilleRisLambers, Janneke; Harpole, W. Stanley; Cleland, Elsa E.; Brown, Cynthia S.; Knops, Johannes M.H.; Prober, Suzanne M.; Pyke, David A.; Farrell, Kelly A.; Bakker, John D.; O'Halloran, Lydia R.; Adler, Peter B.; Collins, Scott L.; D'Antonio, Carla M.; Crawley, Michael J.; Wolkovich, Elizabeth M.; La Pierre, Kimberly J.; Melbourne, Brett A.; Hautier, Yann; Morgan, John W.; Leakey, Andrew D.B.; Kay, Adam; McCulley, Rebecca; Davies, Kendi F.; Stevens, Carly J.; Chu, Cheng-Jin; Holl, Karen D.; Klein, Julia A.; Fay, Phillip A.; Hagenah, Nicole; Kirkman, Kevin P.; Buckley, Yvonne M.
2011-01-01
Many ecosystems worldwide are dominated by introduced plant species, leading to loss of biodiversity and ecosystem function. A common but rarely tested assumption is that these plants are more abundant in introduced vs. native communities, because ecological or evolutionary-based shifts in populations underlie invasion success. Here, data for 26 herbaceous species at 39 sites, within eight countries, revealed that species abundances were similar at native (home) and introduced (away) sites - grass species were generally abundant home and away, while forbs were low in abundance, but more abundant at home. Sites with six or more of these species had similar community abundance hierarchies, suggesting that suites of introduced species are assembling similarly on different continents. Overall, we found that substantial changes to populations are not necessarily a pre-condition for invasion success and that increases in species abundance are unusual. Instead, abundance at home predicts abundance away, a potentially useful additional criterion for biosecurity programmes.
Relative abundance of the southern pine beetle associates in East Texas
John C. Moser; R. C. Thatcher; L. S. Pickard
1971-01-01
More than 90 species of insects were identified in bolts taken from east Texas loblolly pines infested by the southern pine beetle, Dendroctonus frontalis Zimmermann and by Ips engraver beetles (Coleoptera: scolytidae). Seasonal abundance of the associates generally paralleled that of the southern pine beetle.
The abundances of ethane and acetylene in the atmospheres of Jupiter and Saturn
NASA Technical Reports Server (NTRS)
Noll, K. S.; Knacke, R. F.; Tokunaga, A. T.; Lacy, J. H.; Beck, S.
1986-01-01
The present determination of the stratospheric abundances of ethane and acetylene on Jupiter and Saturn on the basis of IR spectra near 780/cm uses atmospheric models whose thermal and density profiles have constant mixing ratios. The ratio of ethane to acetylene is noted to be insensitive to model atmosphere assumptions; it is 55 + or - 31 for Jupiter and 23 + or - 12 where model mixing ratios are uniform. Atmospheric model density profiles adapted from theoretical photochemical models are noted to also yield a higher ethane/acetylene ratios for Jupiter.
The abundances of ethane to acetylene in the atmospheres of Jupiter and Saturn
NASA Technical Reports Server (NTRS)
Noll, K. S.; Knacke, R. F.; Tokunaga, A. T.; Lacy, J. H.; Beck, S.; Serabyn, E.
1986-01-01
The present determination of the stratospheric abundances of ethane and acetylene on Jupiter and Saturn on the basis of IR spectra near 780/cm uses atmospheric models whose thermal and density profiles have constant mixing ratios. The ratio of ethane to acetylene is noted to be insensitive to model atmosphere assumptions; it is 55 + or - 31 for Jupiter and 23 + or - 12 where model mixing ratios are uniform. Atmospheric model density profiles adapted from theoretical photochemical models are noted to also yield a higher ethane/acetylene ratios for Jupiter.
The Th and U abundances in chondritic meteorites
NASA Technical Reports Server (NTRS)
Chen, J. H.; Wasserburg, G. J.; Papanastassiou, D. A.
1993-01-01
We present new analyses of Th-232/U-238 in CI and CM meteorites. The relative abundance of these nuclides is important in estimates of the age of r-process elements. The cosmochronology based upon the Th-232/U-238 ratio (kappa) depends on the precise determinations of these two different elements in meteorites and on the production ratios. Both parameters are subject to substantial errors. Recent recalculations of this chronology have used selected values from compilations but do not adequately address the errors in terms of a reliable data base. Morgan and Lovering provided extensive neutron activation analyses for ordinary chondrites which yield an average kappa of 3.6 +/- 0.4. Their work on carbonaceous chondrites showed a wide range in kappa from 2 to 6. More recent investigations by isotopic dilution have established the following: (1) highly variable kappa from 2.7 to 11 in Allende Ca-Al-rich inclusions and a value of 3.6 in the Orgueil CI1 chondrite; (2) a range from 2.71 to 6.63 for 7 L-type chondrites and a range from 2.7 to 4.4 for 6 L, H, and LL chondrites. A further investigation of this subject matter is presented.
Carmo, A.M.; Stankiewicz, B.A.; Mastalerz, Maria; Pratt, L.M.
1997-01-01
The molecular and elemental composition of immature kerogens isolated from Upper Cretaceous marine carbonates from Sergipe Basin, Brazil were investigated using combined pyrolysis-gas chromatography/mass spectrometry and organic petrographic techniques. The kerogens are predominantly composed of reddish-fluorescing amorphous organic matter (AOM) and variable amounts of yellow-fluorescing alginite and liptodetrinite. The abundance of organic sulfur in the kerogens inferred from the ratio 2-ethyl-5-methylthiophene/(1,2-dimethylbenzene + dec-1-ene) in the pyrolyzates is variable and may be related to changes in the type of primary organic input and/or to variations in rates of bacterial sulfate reduction. A concomitant increase in S/C and O/C ratios determined in situ using the electron microprobe is observed in AOM and alginites and may be related to a progressive oxidation of the organic matter during sulfurization. The S/C ratio of the AOM is systematically higher than the S C ratio of the alginites. Combined with a thiophene distribution characteristic of pyrolyzates of Type II organic matter, the higher S/C of AOM in Sergipe kerogens suggests that sulfurization and incorporation of low-molecular weight lipids derived from normal marine organic matter into the kerogen structure predominated over direct sulfurization of highly aliphatic algal biomacromolecules.The molecular and elemental composition of immature kerogens isolated from Upper Cretaceous marine carbonates from Sergipe Basin, Brazil were investigated using combined pyrolysis-gas chromatography/mass spectrometry and organic petrographic techniques. The kerogens are predominantly composed of reddish-fluorescing amorphous organic matter (AOM) and variable amounts of yellow-fluorescing alginite and liptodetrinite. The abundance of organic sulfur in the kerogens inferred from the ratio 2-ethyl-5-methylthiophene/(1,2-dimethylbenzene+dec-1-ene) in the pyrolyzates is variable and may be related to changes in
Normalization and microbial differential abundance strategies depend upon data characteristics.
Weiss, Sophie; Xu, Zhenjiang Zech; Peddada, Shyamal; Amir, Amnon; Bittinger, Kyle; Gonzalez, Antonio; Lozupone, Catherine; Zaneveld, Jesse R; Vázquez-Baeza, Yoshiki; Birmingham, Amanda; Hyde, Embriette R; Knight, Rob
2017-03-03
Data from 16S ribosomal RNA (rRNA) amplicon sequencing present challenges to ecological and statistical interpretation. In particular, library sizes often vary over several ranges of magnitude, and the data contains many zeros. Although we are typically interested in comparing relative abundance of taxa in the ecosystem of two or more groups, we can only measure the taxon relative abundance in specimens obtained from the ecosystems. Because the comparison of taxon relative abundance in the specimen is not equivalent to the comparison of taxon relative abundance in the ecosystems, this presents a special challenge. Second, because the relative abundance of taxa in the specimen (as well as in the ecosystem) sum to 1, these are compositional data. Because the compositional data are constrained by the simplex (sum to 1) and are not unconstrained in the Euclidean space, many standard methods of analysis are not applicable. Here, we evaluate how these challenges impact the performance of existing normalization methods and differential abundance analyses. Effects on normalization: Most normalization methods enable successful clustering of samples according to biological origin when the groups differ substantially in their overall microbial composition. Rarefying more clearly clusters samples according to biological origin than other normalization techniques do for ordination metrics based on presence or absence. Alternate normalization measures are potentially vulnerable to artifacts due to library size. Effects on differential abundance testing: We build on a previous work to evaluate seven proposed statistical methods using rarefied as well as raw data. Our simulation studies suggest that the false discovery rates of many differential abundance-testing methods are not increased by rarefying itself, although of course rarefying results in a loss of sensitivity due to elimination of a portion of available data. For groups with large (~10×) differences in the average
Mars and Earth: origin and abundance of volatiles.
Anders, E; Owen, T
1977-11-04
Mars, like Earth, may have received its volatiles in the final stages of accretion, as a veneer of volatile-rich material similar to C3V carbonaceous chondrites. The high (40)Ar/(36)Ar ratio and low (36)Ar abundance on Mars, compared to data for other differentiated planets, suggest that Mars is depleted in volatiles relative to Earth-by a factor of 1.7 for K and 14 other moderately volatile elements and by a factor of 35 for (36)Ar and 15 other highly volatile elements. Using these two scaling factors, we have predicted martian abundances of 31 elements from terrestrial abundances. Comparison with the observed (36)Ar abundance suggests that outgassing on Mars has been about four times less complete than on Earth. Various predictions of the model can be checked against observation. The initial abundance of N, prior to escape, was about ten times the present value of 0.62 ppb, in good agreement with an independent estimate based on the observed enhancement in the martian (15)N/(14)N ratio (78,79). The initial water content corresponds to a 9-m layer, close to the value of >/=13 m inferred from the lack of an (18)O/(16)O fractionation (75). The predicted crustal Cl/S ratio of 0.23 agrees exactly with the value measured for martian dust (67); we estimate the thickness of this dust layer to be about 70 m. The predicted surface abundance of carbon, 290 g/cm(2), is 70 times greater than the atmospheric CO(2) value, but the CaCO(3) content inferred for martian dust (67) could account for at least one-quarter of the predicted value. The past atmospheric pressure, prior to formation of carbonates, could have been as high as 140 mbar, and possibly even 500 mbar. Finally, the predicted (129)Xe/(132)Xe ratio of 2.96 agrees fairly well with the observed value of 2.5(+2)(-1) (85). From the limited data available thus far, a curious dichotomy seems to be emerging among differentiated planets in the inner solar system. Two large planets (Earth and Venus) are fairly rich in
Rubidium and Lead Abundances in Giant Stars of the Globular Clusters M13 and NGC 6752
NASA Astrophysics Data System (ADS)
Yong, David; Aoki, Wako; Lambert, David L.; Paulson, Diane B.
2006-03-01
We present measurements of the neutron-capture elements Rb and Pb in five giant stars of the globular cluster NGC 6752 and Pb measurements in four giants of the globular cluster M13. The abundances were derived by comparing synthetic spectra with high-resolution, high signal-to-noise ratio spectra obtained using HDS on the Subaru telescope and MIKE on the Magellan telescope. The program stars span the range of the O-Al abundance variation. In NGC 6752, the mean abundances are [Rb/Fe]=-0.17+/-0.06 (σ=0.14), [Rb/Zr]=-0.12+/-0.06 (σ=0.13), and [Pb/Fe]=-0.17+/-0.04 (σ=0.08). In M13 the mean abundance is [Pb/Fe]=-0.28+/-0.03 (σ=0.06). Within the measurement uncertainties, we find no evidence for star-to-star variation for either Rb or Pb within these clusters. None of the abundance ratios [Rb/Fe], [Rb/Zr], or [Pb/Fe] are correlated with the Al abundance. NGC 6752 may have slightly lower abundances of [Rb/Fe] and [Rb/Zr] compared to the small sample of field stars at the same metallicity. For M13 and NGC 6752 the Pb abundances are in accord with predictions from a Galactic chemical evolution model. If metal-poor intermediate-mass asymptotic giant branch stars did produce the globular cluster abundance anomalies, then such stars do not synthesize significant quantities of Rb or Pb. Alternatively, if such stars do synthesize large amounts of Rb or Pb, then they are not responsible for the abundance anomalies seen in globular clusters. Based in part on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan, and on observations made with the Magellan Clay Telescope at Las Campanas Observatory.
NASA Technical Reports Server (NTRS)
Wiedenbeck, M. E.
1977-01-01
An instrument, the Caltech High Energy Isotope Spectrometer Telescope was developed to measure isotopic abundances of cosmic ray nuclei by employing an energy loss - residual energy technique. A detailed analysis was made of the mass resolution capabilities of this instrument. A formalism, based on the leaky box model of cosmic ray propagation, was developed for obtaining isotopic abundance ratios at the cosmic ray sources from abundances measured in local interstellar space for elements having three or more stable isotopes, one of which is believed to be absent at the cosmic ray sources. It was shown that the dominant sources of uncertainty in the derived source ratios are uncorrelated errors in the fragmentation cross sections and statistical uncertainties in measuring local interstellar abundances. These results were applied to estimate the extent to which uncertainties must be reduced in order to distinguish between cosmic ray production in a solar-like environment and in various environments with greater neutron enrichments.
Nenninger, Heather; Koper, Nicola
2017-01-01
The rapid expansion of oil and natural gas development across the Northern Great Plains has contributed to habitat fragmentation, which may facilitate brood parasitism of ground-nesting grassland songbird nests by brown-headed cowbirds (Molothrus ater), an obligate brood parasite, through the introduction of perches and anthropogenic edges. We tested this hypothesis by measuring brown-headed cowbird relative abundance and brood parasitism rates of Savannah sparrow (Passerculus sandwichensis) nests in relation to the presence of infrastructure features and proximity to potential perches and edge habitat. The presence of oil and natural gas infrastructure increased brown-headed cowbird relative abundance by a magnitude of four times, which resulted in four times greater brood parasitism rates at infrastructure sites. While the presence of infrastructure and the proximity to roads were influential in predicting brood parasitism rates, the proximity of perch sites was not. This suggests that brood parasitism associated with oil and natural gas infrastructure may result in additional pressures that reduce productivity of this declining grassland songbird. PMID:28791134
Extreme possible variations of the deuterium abundance within the Galaxy
NASA Astrophysics Data System (ADS)
Delbourgo-Salvador, P.; Audouze, J.; Vidal-Madjar, A.
1987-03-01
In order to reconcile the present baryonic densities deduced respectively from the primordial abundances of D and 4He, some recent chemical evolution models imply that D could have been destroyed more thoroughly during the Galaxy evolution than what was previously predicted. Under the conditions outlined by these models, the present abundance of D may vary by factors as large as 50 in different parts of the Galaxy. If such variations are not observed, this implies that the ratio X(D)prim/X(D)present is not large (2 - 3): the simplest Big Bang models may then be unable to reconcile the baryonic densities predicted by D and 4He respectively.
Empirical relationships between gas abundances and UV selective extinction
NASA Technical Reports Server (NTRS)
Joseph, Charles L.
1990-01-01
Several studies of gas-phase abundances in lines of sight through the outer edges of dense clouds are summarized. These lines of sight have 0.4 less than E(B-V) less than 1.1 and have inferred spatial densities of a few hundred cm(-3). The primary thrust of these studies has been to compare gaseous abundances in interstellar clouds that have various types of peculiar selective extinction. To date, the most notable result has been an empirical relationship between the CN/Fe I abundance ratio and the depth of the 2200 A extinction bump. It is not clear at the present time, however, whether these two parameters are linearly correlated or the data are organized into two discrete ensembles. Based on 19 samples and assuming the clouds form discrete ensembles, lines of sight that have a CN/Fe I abundance ratio greater than 0.3 (dex) appear to have a shallow 2.57 plus or minus 0.55 bump compared to 3.60 plus or minus 0.36 for other dense clouds and compared to the 3.6 Seaton (1979) average. The difference in the strength of the extinction bump between these two ensembles is 1.03 plus or minus 0.23. Although a high-resolution IUE survey of dense clouds is far from complete, the few lines of sight with shallow extinction bumps all show preferential depletion of certain elements, while those lines of sight with normal 2200 A bumps do not. Ca II, Cr II, and Mn II appear to exhibit the strongest preferential depletion compared to S II, P II, and Mg II. Fe II and Si II depletions also appear to be enhanced somewhat in the shallow-bump lines of sight. It should be noted that Copernicus data suggest all elements, including the so-called nondepletors, deplete in diffuse clouds (Snow and Jenkins 1980, Joseph 1988). Those lines of sight through dense clouds that have normal 2200 A extinction bumps appear to be extensions of the depletions found in the diffuse interstellar medium. That is, the overall level of depletion is enhanced, but the element-to-element abundances are similar to
Sutherland, Chris; Royle, Andy
2016-01-01
This chapter provides a non-technical overview of ‘closed population capture–recapture’ models, a class of well-established models that are widely applied in ecology, such as removal sampling, covariate models, and distance sampling. These methods are regularly adopted for studies of reptiles, in order to estimate abundance from counts of marked individuals while accounting for imperfect detection. Thus, the chapter describes some classic closed population models for estimating abundance, with considerations for some recent extensions that provide a spatial context for the estimation of abundance, and therefore density. Finally, the chapter suggests some software for use in data analysis, such as the Windows-based program MARK, and provides an example of estimating abundance and density of reptiles using an artificial cover object survey of Slow Worms (Anguis fragilis).
A nondestructive technique to monitor the relative abundance of terrestrial salamanders
Richard M. DeGraaf; Mariko Yamasaki
1992-01-01
Salamanders are abundant vertebrates in many forest ecosystems, and their annual biomass production can be important in forest food webs (Pough et al. 1987). Population densities of eastern redback salamanders (Plethodon cinereus) can exceed 2 individuals/m2 in deciduous forests of the United States (Heatwole 1962, Jaeger 1980...
VizieR Online Data Catalog: Abundance ratio for 5 local stellar associations (Reddy+, 2015)
NASA Astrophysics Data System (ADS)
Reddy, A. B. S.; Lambert, D. L.
2018-01-01
In this paper, we have performed a homogeneous and a comprehensive abundance analysis using high-resolution spectroscopy. High-resolution and high signal-to-noise (S/N) spectra of the program stars were obtained during the nights of 2015 February 10-11 with the Robert G. Tull coude cross-dispersed echelle spectrograph (Tull et al. 1995PASP..107..251T) of the 2.7 m Harlan J. Smith reflector at the McDonald Observatory. We employed a Tektronix 2048x2048 24 μm pixel, backside illuminated and anti-reflection coated CCD as a detector and an R2 echelle grating with 52.67 grooves/mm with exposures centred at 5060 Å. (7 data files).
Abundances of sulfur in the Milky Way Disk from Peimbert Type II planetary nebulae
NASA Astrophysics Data System (ADS)
Milingo, Jacquelynne Brenda
2000-08-01
Sulfur abundance gradients and heavy element ratios for the Milky Way Disk are constructed based upon newly acquired spectrophotometry of Type II planetary nebulae (PN). These spectra extend from 3600-9600 angstroms allowing us to use the [SIII] 9069 and 9532 angstrom lines to improve upon earlier sulfur abundance estimates. Considering a significant portion of sulfur in PN exists in the S(+2) ionization stage (and higher) this method should allow us to extrapolate more reliable total element abundance from ionic abundances. Given the progenitor mass and location of Type II PN (close to the Galactic disk), this sample of objects is free of nucleosynthetic self-contamination and thus their S abundances in particular are expected to reflect levels of these elements in the interstellar medium at the time of PN progenitor formation. These sulfur abundances provide constraints for studying various aspects of GCE such as massive star yields and the distribution of S across the Milky Way disk.
Han, Minqi; Liu, Fang; Zhang, Fengli; Li, Zhiyong; Lin, Houwen
2012-12-01
Many biologically active natural products have been isolated from Phakellia fusca, an indigenous sponge in the South China Sea; however, the microbial symbionts of Phakellia fusca remain unknown. The present investigations on sponge microbial community are mainly based on qualitative analysis, while quantitative analysis, e.g., relative abundance, is rarely carried out, and little is known about the roles of microbial symbionts. In this study, the community structure and relative abundance of bacteria, actinobacteria, and archaea associated with Phakellia fusca were revealed by 16S rRNA gene library-based sequencing and quantitative real time PCR (qRT-PCR). The ammonia-oxidizing populations were investigated based on amoA gene and anammox-specific 16S rRNA gene libraries. As a result, it was found that bacterial symbionts of sponge Phakellia fusca consist of Proteobacteria including Gamma-, Alpha-, and Delta-proteobacteria, Cyanobacteria with Gamma-proteobacteria as the predominant components. In particular, the diversity of actinobacterial symbionts in Phakellia fusca is high, which is composed of Corynebacterineae, Acidimicrobidae, Frankineae, Micrococcineae, and Streptosporangineae. All the observed archaea in sponge Phakellia fusca belong to Crenarchaeota, and the detected ammonia-oxidizing populations are ammonia-oxidizing archaea, suggesting the nitrification function of sponge archaeal symbionts. According to qRT-PCR analysis, bacterial symbionts dominated the microbial community, while archaea represented the second predominant symbionts, followed by actinobacteria. The revealed diverse prokaryotic symbionts of Phakellia fusca are valuable for the understanding and in-depth utilization of Phakellia fusca microbial symbionts. This study extends our knowledge of the community, especially the relative abundance of microbial symbionts in sponges.
Planetary Nebula Abundances and Morphology: Probing the Chemical Evolution of the Milky Way
NASA Astrophysics Data System (ADS)
Stanghellini, Letizia; Guerrero, Martín Antonio; Cunha, Katia; Manchado, Arturo; Villaver, Eva
2006-11-01
This paper presents a homogeneous study of abundances in a sample of 79 northern Galactic planetary nebulae (PNe) whose morphological classes have been uniformly determined. Ionic abundances and plasma diagnostics were derived from selected optical line strengths in the literature, and elemental abundances were estimated with the ionization correction factor developed by Kingsbourgh & Barlow in 1994. We compare the elemental abundances to the final yields obtained from stellar evolution models of low- and intermediate-mass stars, and we confirm that most bipolar PNe have high nitrogen and helium abundance and are the likely progeny of stars with main-sequence mass greater than 3 Msolar. We derive =0.27 and discuss the implication of such a high ratio in connection with the solar neon abundance. We determine the Galactic gradients of oxygen and neon and found Δlog(O/H)/ΔR=-0.01 dex kpc-1 and Δlog(Ne/H)/ΔR=-0.01 dex kpc-1. These flat PN gradients are irreconcilable with Galactic metallicity gradients flattening with time.
Rare-earth abundances in chondritic meteorites
NASA Technical Reports Server (NTRS)
Evensen, N. M.; Hamilton, P. J.; Onions, R. K.
1978-01-01
Fifteen chondrites, including eight carbonaceous chondrites, were analyzed for rare earth element abundances by isotope dilution. Examination of REE for a large number of individual chondrites shows that only a small proportion of the analyses have flat unfractionated REE patterns within experimental error. While some of the remaining analyses are consistent with magmatic fractionation, many patterns, in particular those with positive Ce anomalies, can not be explained by known magmatic processes. Elemental abundance anomalies are found in all major chondrite classes. The persistence of anomalies in chondritic materials relatively removed from direct condensational processes implies that anomalous components are resistant to equilibrium or were introduced at a late stage of chondrite formation. Large-scale segregation of gas and condensate is implied, and bulk variations in REE abundances between planetary bodies is possible.
NASA Astrophysics Data System (ADS)
Sakari, Charli; Venn, Kim; Mackey, Dougal; Shetrone, Matthew D.; Dotter, Aaron L.; Wallerstein, George
2015-01-01
Detailed chemical abundances of globular clusters provide insight into the formation and evolution of galaxies and their globular cluster systems. This talk presents detailed chemical abundances for seven M31 outer halo globular clusters (with projected radii greater than 30 kpc), as derived from high resolution integrated light spectra. Five of these clusters were recently discovered in the Pan-Andromeda Archaeological Survey (PAndAS). The integrated abundances show that 4 of these clusters are metal-poor ([Fe/H] < -1.5) while the other 3 are more metal-rich. The most metal-poor globular clusters are α-enhanced, though 3 of the 4 are possibly less α-enhanced than MW stars (at the 1σ level). Other chemical abundance ratios ([Ba/Eu], [Eu/Ca], and [Ni/Fe]) are consistent with origins in low mass dwarf galaxies (similar to Fornax). The most metal-rich cluster ([Fe/H] ~ -1) stands out as being chemically distinct from Milky Way field stars of the same metallicity---its chemical abundance ratios agree best with the stars and clusters in the Large Magellanic Cloud (LMC) and the Sagittarius dwarf spheroidal (Sgr) than with the Milky Way field stars. The other metal-rich clusters, H10 and H23, look similar to the LMC and Milky Way field stars in all abundance ratios. These results indicate that M31's outer halo is being at least partially built up by the accretion of dwarf satellites, in agreement with previous observations.
The 12C/13C Isotopic Ratio in Planetary Nebulae as Deduced from IUE Data
NASA Astrophysics Data System (ADS)
Miskey, C. L.; Feibelman, W. A.; Bruhweiler, F. C.
2000-05-01
The relative abundances of C, N, and O and the isotopic ratio of 12C/13C represent tracers of nucleosynthesis in intermediate stars with main-sequence masses between 0.6 and 8.0 solar masses in our Galaxy. Determining these abundances and the isotopic 12C/13C ratio in planetary nebulae (PNe) represent perhaps the best means to discern exactly how the ISM is enriched by CNO stellar nucleosynthesis. Walsh et al. (1996) and Clegg et al. (1997), using the Hubble Space Telescope, have derived the isotopic 12C/13C abundance ratio in the galactic carbon-rich PN, NGC 3918, and placed marginal constraints on it for the Magellanic PNe, N2 (SMC) and N122 (LMC). This was done using the well-known 12C 3P-1S (J=1-0 and J=2-0) transitions of C+2 at 1906.68 Angstroms and 1908.77 Angstroms and a J=0-0 transition at 1909.6 Angstroms, which is strictly forbidden in 12C. The finite nuclear spin of 13C (I=1/2) permits a corresponding F=1/2-1/2 electric dipole transition not seen in 12C. Since the 1909.6 Angstroms line is well separated from the other two 12C transitions, it provides an important means of determining 12C/13C in planetary nebulae. We have just completed a search of archival International Ultraviolet Explorer (IUE) high-dispersion spectra of approximately three dozen PNe, and derived 12C/13C ratios of 39 and 23 for the galactic PNe, NGC 2440 and NGC 6302, respectively. These are values much lower than the solar value of 89. In the other objects, the limited S/N of the IUE data indicate 12C/13C ratio upper limits much higher than 50. The implications of these results and their pertinence to stellar evolution are discussed.
NASA Astrophysics Data System (ADS)
Cazorla, Constantin; Nazé, Yaël; Morel, Thierry; Georgy, Cyril; Godart, Mélanie; Langer, Norbert
2017-08-01
Aims: Past observations of fast-rotating massive stars exhibiting normal nitrogen abundances at their surface have raised questions about the rotational mixing paradigm. We revisit this question thanks to a spectroscopic analysis of a sample of bright fast-rotating OB stars, with the goal of quantifying the efficiency of rotational mixing at high rotation rates. Methods: Our sample consists of 40 fast rotators on the main sequence, with spectral types comprised between B0.5 and O4. We compare the abundances of some key element indicators of mixing (He, CNO) with the predictions of evolutionary models for single objects and for stars in interacting binary systems. Results: The properties of half of the sample stars can be reproduced by single evolutionary models, even in the case of probable or confirmed binaries that can therefore be true single stars in a pre-interaction configuration. The main problem for the rest of the sample is a mismatch for the [N/O] abundance ratio (we confirm the existence of fast rotators with a lack of nitrogen enrichment) and/or a high helium abundance that cannot be accounted for by models. Modifying the diffusion coefficient implemented in single-star models does not solve the problem as it cannot simultaneously reproduce the helium abundances and [N/O] abundance ratios of our targets. Since part of them actually are binaries, we also compared their chemical properties with predictions for post-mass transfer systems. We found that these models can explain the abundances measured for a majority of our targets, including some of the most helium-enriched, but fail to reproduce them in other cases. Our study thus reveals that some physical ingredients are still missing in current models.
Jami E. MacNeil; Rod N. Williams
2013-01-01
Terrestrial salamanders are ideal indicators of forest ecosystem integrity due to their abundance, their role in nutrient cycling, and their sensitivity to environmental change. To understand better how terrestrial salamanders are affected by forest management practices, we monitored species diversity and abundance before implementation of timber harvests within the...
NASA Astrophysics Data System (ADS)
Dello Russo, Neil; DiSanti, Michael A.; Kawakita, Hideyo; Shinnaka, Yoshiharu; Vervack, Ronald J.; Bonev, Boncho P.; Gibb, Erika L.; Roth, Nathan; McKay, Adam J.; Weaver, Harold A.; Cochran, Anita L.
2017-10-01
Two major shortcomings in chemically classifying comets at infrared wavelengths are a lack of hypervolatile (CO and CH4) detections in Jupiter-family comets and incomplete temporal coverage of comet chemistry, particularly at small heliocentric distances (Rh). We report post-perihelion volatile abundances in comet 45P/Honda-Mrkos-Pajdusakova with the high-resolution infrared spectrometer iSHELL at the NASA/IRTF on UT 6 - 8 January when Rh = 0.55 AU (DiSanti et al. 2017, Astron. J., in press), and with NIRSPEC at the Keck Observatory on UT 13 and 19 February when Rh = 1.0 and 1.1 AU, respectively. Favorable comet geocentric velocities enabled the detection of CO and CH4 in early January and 19 February. The relative abundance of CO is severely depleted whereas CH4 is typical to enriched in 45P when compared to comets from the Oort cloud. Significant differences are seen in relative abundances of species between January and February, notably in the ratio of C2H2/HCN. We explore whether the heliocentric distances of the measurements or seasonal changes primarily cause these differences by comparing to observations of C/2012 S1 ISON obtained over a similar range of heliocentric distances. NASA and NSF research grants support this work. We also acknowledge the expert support of the IRTF and Keck support staffs during these observations.
The Mean Life Squared Relationship for Abundances of Extinct Radioactivities
NASA Technical Reports Server (NTRS)
Lodders, K.; Cameron, A. G. W.
2004-01-01
We discovered that the abundances of now extinct radioactivities (relative to stable reference isotopes) in meteorites vary as a function of their mean lifetimes squared. This relationship applies to chondrites, achondrites, and irons but to calcium-aluminum inclusions (CAIs). Certain meteorites contain excesses in isotopic abundances from the decay of radioactive isotopes with half-lives much less than the age of the solar system. These short-lived radioactivities are now extinct, but they were alive when meteorites assembled in the early solar system. The origin of these radioactivities and the processes which control their abundances in the solar nebula are still not well understood. Some clues may come from our finding that the meteoritic abundances of now extinct radioactivities (relative to stable reference isotopes) vary as a function of their mean lifetimes squared. This relationship applies to chondrites, achondrites, and irons, but not to CAIs. This points to at least two different processes establishing the abundances of short-lived isotopes found in the meteoritic record.
NASA Astrophysics Data System (ADS)
Brower, Amelia A.; Ferguson, Megan C.; Schonberg, Susan V.; Jewett, Stephen C.; Clarke, Janet T.
2017-10-01
The shallow continental shelf waters of the Bering and Chukchi seas are the northernmost foraging grounds of North Pacific gray whales (Eschrichtius robustus). Benthic amphipods are considered the primary prey of gray whales in these waters, although no comprehensive quantitative analysis has been performed to support this assumption. Gray whale relative abundance, distribution, and behavior in the northeastern Chukchi Sea (69°-72°N, 155-169°W) were documented during aerial surveys in June-October 2009-2012. Concurrently, vessel-based benthic infaunal sampling was conducted in the area in July-August 2009-10, September 2011, and August 2012. Gray whales were seen in the study area each month that surveys were conducted, with the majority of whales feeding. Statistical analyses confirm that the highest densities of feeding gray whales were associated with high benthic amphipod abundance, primarily within 70 km of shore from Point Barrow to Icy Cape, in water <50 m deep. Conversely, gray whales were not seen in 40-km×40-km cells containing benthic sampling stations with 85 m-2 or fewer amphipods. Continuing broad-scale aerial surveys in the Chukchi Sea and prey sampling near feeding gray whales will be an important means to monitor and document ongoing and predicted ecosystem changes.
Silicon to iron abundances in solar cosmic rays and in the sun
NASA Technical Reports Server (NTRS)
Vahia, M. N.; Biswas, S.; Durgaprasad, N.
1985-01-01
Differential spectra of even charged nuclei between Si and Fe in the August 4, 1972 event were made in the energy region of 10 to 40 MeV/n-1 using rocket borne plastic detectors. The resulting relative abundances of elements and low energy enhancements are obtained and compared with spectroscopically determined photospheric abundances. The implications of the relative abundances on the acceleration mechanisms is discussed.
Clustering in the stellar abundance space
NASA Astrophysics Data System (ADS)
Boesso, R.; Rocha-Pinto, H. J.
2018-03-01
We have studied the chemical enrichment history of the interstellar medium through an analysis of the n-dimensional stellar abundance space. This work is a non-parametric analysis of the stellar chemical abundance space. The main goal is to study the stars from their organization within this abundance space. Within this space, we seek to find clusters (in a statistical sense), that is, stars likely to share similar chemo-evolutionary history, using two methods: the hierarchical clustering and the principal component analysis. We analysed some selected abundance surveys available in the literature. For each sample, we labelled the group of stars according to its average abundance curve. In all samples, we identify the existence of a main enrichment pattern of the stars, which we call chemical enrichment flow. This flow is set by the structured and well-defined mean rate at which the abundances of the interstellar medium increase, resulting from the mixture of the material ejected from the stars and stellar mass-loss and interstellar medium gas. One of the main results of our analysis is the identification of subgroups of stars with peculiar chemistry. These stars are situated in regions outside of the enrichment flow in the abundance space. These peculiar stars show a mismatch in the enrichment rate of a few elements, such as Mg, Si, Sc and V, when compared to the mean enrichment rate of the other elements of the same stars. We believe that the existence of these groups of stars with peculiar chemistry may be related to the accretion of planetary material on to stellar surfaces or may be due to production of the same chemical element by different nucleosynthetic sites.
Rapid processing of 85Kr/Kr ratios using Atom Trap Trace Analysis
DOE Office of Scientific and Technical Information (OSTI.GOV)
Zappala, J. C.; Bailey, K.; Mueller, P.
In this paper, we report a methodology for measuring 85Kr/Kr isotopic abundances using Atom Trap Trace Analysis (ATTA) that increases sample measurement throughput by over an order of magnitude to six samples per 24 h. The noble gas isotope 85Kr (half-life = 10.7 years) is a useful tracer for young groundwater in the age range of 5–50 years. ATTA, an efficient and selective laser-based atom counting method, has recently been applied to 85Kr/Kr isotopic abundance measurements, requiring 5–10 μL of krypton gas at STP extracted from 50 to 100 L of water. Previously, a single such measurement required 48 h.more » In conclusion, our new method demonstrates that we can measure 85Kr/Kr ratios with 3–5% relative uncertainty every 4 h, on average, with the same sample requirements.« less
Rapid processing of 85Kr/Kr ratios using Atom Trap Trace Analysis
Zappala, J. C.; Bailey, K.; Mueller, P.; ...
2017-03-11
In this paper, we report a methodology for measuring 85Kr/Kr isotopic abundances using Atom Trap Trace Analysis (ATTA) that increases sample measurement throughput by over an order of magnitude to six samples per 24 h. The noble gas isotope 85Kr (half-life = 10.7 years) is a useful tracer for young groundwater in the age range of 5–50 years. ATTA, an efficient and selective laser-based atom counting method, has recently been applied to 85Kr/Kr isotopic abundance measurements, requiring 5–10 μL of krypton gas at STP extracted from 50 to 100 L of water. Previously, a single such measurement required 48 h.more » In conclusion, our new method demonstrates that we can measure 85Kr/Kr ratios with 3–5% relative uncertainty every 4 h, on average, with the same sample requirements.« less
Sodium-to-Potassium Ratio and Blood Pressure, Hypertension, and Related Factors12
Perez, Vanessa; Chang, Ellen T.
2014-01-01
The potential cost-effectiveness and feasibility of dietary interventions aimed at reducing hypertension risk are of considerable interest and significance in public health. In particular, the effectiveness of restricted sodium or increased potassium intake on mitigating hypertension risk has been demonstrated in clinical and observational research. The role that modified sodium or potassium intake plays in influencing the renin-angiotensin system, arterial stiffness, and endothelial dysfunction remains of interest in current research. Up to the present date, no known systematic review has examined whether the sodium-to-potassium ratio or either sodium or potassium alone is more strongly associated with blood pressure and related factors, including the renin-angiotensin system, arterial stiffness, the augmentation index, and endothelial dysfunction, in humans. This article presents a systematic review and synthesis of the randomized controlled trials and observational research related to this issue. The main findings show that, among the randomized controlled trials reviewed, the sodium-to-potassium ratio appears to be more strongly associated with blood pressure outcomes than either sodium or potassium alone in hypertensive adult populations. Recent data from the observational studies reviewed provide additional support for the sodium-to-potassium ratio as a superior metric to either sodium or potassium alone in the evaluation of blood pressure outcomes and incident hypertension. It remains unclear whether this is true in normotensive populations and in children and for related outcomes including the renin-angiotensin system, arterial stiffness, the augmentation index, and endothelial dysfunction. Future study in these populations is warranted. PMID:25398734
Spatial patterns in the abundance of the coastal horned lizard
Fisher, Robert N.; Suarez, Andrew V.; Case, Ted J.
2002-01-01
Coastal horned lizards ( Phrynosoma coronatum) have undergone severe declines in southern California and are a candidate species for state and federal listing under the Endangered Species Act. Quantitative data on their habitat use, abundance, and distribution are lacking, however. We investigated the determinants of abundance for coastal horned lizards at multiple spatial scales throughout southern California. Specifically, we estimated lizard distribution and abundance by establishing 256 pitfall trap arrays clustered within 21 sites across four counties. These arrays were sampled bimonthly for 2–3 years. At each array we measured 26 “local” site descriptors and averaged these values with other “regional” measures to determine site characteristics. Our analyses were successful at identifying factors within and among sites correlated with the presence and abundance of coastal horned lizards. These factors included the absence of the invasive Argentine ant ( Linepithema humile) (and presence of native ant species eaten by the lizards), the presence of chaparral community plants, and the presence of sandy substrates. At a regional scale the relative abundance of Argentine ants was correlated with the relative amount of developed edge around a site. There was no evidence for spatial autocorrelation, even at the scale of the arrays within sites, suggesting that the determinants of the presence or absence and abundance of horned lizard can vary over relatively small spatial scales ( hundreds of meters). Our results suggest that a gap-type approach may miss some of the fine-scale determinants of species abundance in fragmented habitats.
Takayasu, Lena; Suda, Wataru; Watanabe, Eiichiro; Fukuda, Shinji; Takanashi, Kageyasu; Ohno, Hiroshi; Takayasu, Misako; Takayasu, Hideki; Hattori, Masahira
2017-01-01
The gut microbiome is highly variable among individuals, largely due to differences in host lifestyle and physiology. However, little is known about the underlying processes or rules that shape the complex microbial community. In this paper, we show that the cumulative relative abundance distribution (CRAD) of microbial species can be approximated by a power law function, and found that the power exponent of CRADs generated from 16S rRNA gene and metagenomic data for normal gut microbiomes of humans and mice was similar consistently with ∼0.9. A similarly robust power exponent was observed in CRADs of gut microbiomes during dietary interventions and several diseases. However, the power exponent was found to be ∼0.6 in CRADs from gut microbiomes characterized by lower species richness, such as those of human infants and the small intestine of mice. In addition, the CRAD of gut microbiomes of mice treated with antibiotics differed slightly from those of infants and the small intestines of mice. Based on these observations, in addition to data on the spatial distribution of microbes in the digestive tract, we developed a 3-dimensional mathematical model of microbial proliferation that reproduced the experimentally observed CRAD patterns. Our model indicated that the CRAD may be determined by the ratio of emerging to pre-existing species during non-uniform spatially competitive proliferation, independent of species composition. PMID:28792501
Chemical Abundances of Metal-poor RR Lyrae Stars in the Magellanic Clouds
NASA Astrophysics Data System (ADS)
Haschke, Raoul; Grebel, Eva K.; Frebel, Anna; Duffau, Sonia; Hansen, Camilla J.; Koch, Andreas
2012-09-01
We present for the first time a detailed spectroscopic study of chemical element abundances of metal-poor RR Lyrae stars in the Large and Small Magellanic Cloud (LMC and SMC). Using the MagE echelle spectrograph at the 6.5 m Magellan telescopes, we obtain medium resolution (R ~ 2000-6000) spectra of six RR Lyrae stars in the LMC and three RR Lyrae stars in the SMC. These stars were chosen because their previously determined photometric metallicities were among the lowest metallicities found for stars belonging to the old populations in the Magellanic Clouds. We find the spectroscopic metallicities of these stars to be as low as [Fe/H]spec = -2.7 dex, the lowest metallicity yet measured for any star in the Magellanic Clouds. We confirm that for metal-poor stars, the photometric metallicities from the Fourier decomposition of the light curves are systematically too high compared to their spectroscopic counterparts. However, for even more metal-poor stars below [Fe/H]phot < -2.8 dex this trend is reversed and the spectroscopic metallicities are systematically higher than the photometric estimates. We are able to determine abundance ratios for 10 chemical elements (Fe, Na, Mg, Al, Ca, Sc, Ti, Cr, Sr, and Ba), which extend the abundance measurements of chemical elements for RR Lyrae stars in the Clouds beyond [Fe/H] for the first time. For the overall [α/Fe] ratio, we obtain an overabundance of 0.36 dex, which is in very good agreement with results from metal-poor stars in the Milky Way halo as well as from the metal-poor tail in dwarf spheroidal galaxies. Comparing the abundances with those of the stars in the Milky Way halo we find that the abundance ratios of stars of both populations are consistent with another. Therefore, we conclude that from a chemical point of view early contributions from Magellanic-type galaxies to the formation of the Galactic halo as claimed in cosmological models are plausible. This paper includes data gathered with the 6.5 meter Magellan
VizieR Online Data Catalog: C and O isotopic ratios in Arcturus and Aldebaran (Abia+ 2012)
NASA Astrophysics Data System (ADS)
Abia, C.; Palmerini, S.; Busso, M.; Cristallo, S.
2012-10-01
CNO abundances, C and O isotopic ratios and equivalent diffusive coefficients (D) are given for the calculated extra-mixing models. For Arcturus we used the electronic version of the Infrared Atlas Spectrum by Hinkle et al. (1995, Cat. J/PASP/107/1042; resolution 0.01cm-1), and for Aldebaran we used a spectrum obtained on February 6, 1980 at the KPNO 4m Coude telescope using a Fourier transform spectrometer, kindly provided by K. Hinkle (resolution 0.016cm-1) The first 2 rows of table4 report the CNO abundances and isotopic ratios resulting from the observations. The other rows give the CNO abundances and isotopic ratios accounted for by the FDU in the three stellar models considered of 1.3Mo, 1.2Mo and 1.08Mo (see the paper for more details). (1 data file).
Reverchon, Frédérique; Bai, Shahla H.; Liu, Xian; Blumfield, Timothy J.
2015-01-01
Tree mono-plantations are susceptible to soil nutrient impoverishment and mixed species plantations have been proposed as a way of maintaining soil fertility while enhancing biodiversity. In the Solomon Islands, mixed species plantations where teak (Tectona grandis) is inter-planted with a local tree species (Flueggea flexuosa) have been used as an alternative to teak mono-plantations and are expected to increase soil microbial diversity and modify microbial biogeochemical processes. In this study, we quantified the abundance of microbial functional genes involved in the nitrogen (N) cycle from soil samples collected in teak, flueggea, and mixed species plantations. Furthermore, we measured soil properties such as pH, total carbon (C) and total N, stable N isotope composition (δ15N), and inorganic N pools. Soil pH and δ15N were higher under teak than under flueggea, which indicates that intercropping teak with flueggea may decrease bacterial activities and potential N losses. Higher C:N ratios were found under mixed species plantations than those under teak, suggesting an enhancement of N immobilization that would help preventing fast N losses. However, inorganic N pools remained unaffected by plant cover. Inter-planting teak with flueggea in mixed species plantations generally increased the relative abundance of denitrification genes and promoted the enrichment of nosZ-harboring denitrifiers. However, it reduced the abundance of bacterial amoA (ammonia monooxygenase) genes compared to teak mono-plantations. The abundance of most denitrification genes correlated with soil total N and C:N ratio, while bacterial and archeal nitrification genes correlated positively with soil NH4+ concentrations. Altogether, these results show that the abundance of bacterial N-cycling functional guilds vary under teak and under mixed species plantations, and that inter-planting teak with flueggea may potentially alleviate N losses associated with nitrification and denitrification
The Abundance and Isotopic Composition of Water in Howardite-Eucrite-Diogenite Meteorites
NASA Astrophysics Data System (ADS)
Barrett, T. J.; Tartèse, R.; Anand, M.; Franchi, I. A.; Grady, M. M.; Greenwood, R. C.; Charlier, B. L. A.
2014-09-01
Using SIMs techniques we measure OH abundances and D/H ratios in apatite grains from two Eucrites (DaG 945, DaG 844).The average δD values of these two samples are also similar to carbonaceous chondrites, the Earth and the Moon.
Relative Abundance in Bacterial and Fungal Gut Microbes in Obese Children: A Case Control Study.
Borgo, Francesca; Verduci, Elvira; Riva, Alessandra; Lassandro, Carlotta; Riva, Enrica; Morace, Giulia; Borghi, Elisa
2017-02-01
Differences in relative proportions of gut microbial communities in adults have been correlated with intestinal diseases and obesity. In this study we evaluated the gut microbiota biodiversity, both bacterial and fungal, in obese and normal-weight school-aged children. We studied 28 obese (mean age 10.03 ± 0.68) and 33 age- and sex-matched normal-weight children. BMI z-scores were calculated, and the obesity condition was defined according to the WHO criteria. Fecal samples were analyzed by 16S rRNA amplification followed by denaturing gradient gel electrophoresis (DGGE) analysis and sequencing. Real-time polymerase chain reaction (PCR) was performed to quantify the most representative microbial species and genera. DGGE profiles showed high bacterial biodiversity without significant correlations with BMI z-score groups. Compared to bacterial profiles, we observed lower richness in yeast species. Sequence of the most representative bands gave back Eubacterium rectale, Saccharomyces cerevisiae, Candida albicans, and C. glabrata as present in all samples. Debaryomyces hansenii was present only in two obese children. Obese children revealed a significantly lower abundance in Akkermansia muciniphyla, Faecalibacterium prausnitzii, Bacteroides/Prevotella group, Candida spp., and Saccharomyces spp. (P = 0.031, P = 0.044, P = 0.003, P = 0.047, and P = 0.034, respectively). Taking into account the complexity of obesity, our data suggest that differences in relative abundance of some core microbial species, preexisting or diet driven, could actively be part of its etiology. This study improved our knowledge about the fungal population in the pediatric school-age population and highlighted the need to consider the influence of cross-kingdom relationships.
New Constraints on the Abundance of 60Fe in the Early Solar System
NASA Astrophysics Data System (ADS)
Trappitsch, Reto; Boehnke, Patrick; Stephan, Thomas; Telus, Myriam; Savina, Michael R.; Pardo, Olivia; Davis, Andrew M.; Dauphas, Nicolas; Pellin, Michael J.; Huss, Gary R.
2018-04-01
Establishing the abundance of the extinct radionuclide 60Fe (half-life 2.62 Ma) in the early solar system is important for understanding the astrophysical context of solar system formation. While bulk measurements of early solar system phases show a low abundance consistent with galactic background, some in situ measurements by secondary ion mass spectrometry (SIMS) imply a higher abundance, which would require injection from a nearby supernova (SN). Here we present in situ nickel isotopic analyses by resonance ionization mass spectrometry (RIMS) in a chondrule from the primitive meteorite Semarkona (LL3.00). The same chondrule had been previously analyzed by SIMS. Despite improved precision compared to SIMS, the RIMS nickel isotopic data do not reveal any resolved excesses of 60Ni that could be unambiguously ascribed to in situ 60Fe decay. Linear regression of 60Ni/58Ni versus 56Fe/58Ni yields an initial 60Fe/56Fe ratio for this chondrule of (3.8 ± 6.9) × 10‑8, which is consistent with both the low initial value found by bulk measurements and the low end of the range of initial ratios inferred from some in situ work. The same regression also gives a solar initial 60Ni/58Ni ratio, which shows that this sample was not disturbed by nickel mobilization, thus agreeing with a low initial 60Fe/56Fe ratio. These findings agree with a re-evaluation of previous SIMS measurements of the same sample. Supernova injection of 60Fe into the solar system or its parental cloud material is therefore not necessary to account for the measured solar system’s initial amount of 60Fe.
Container surveys were conducted in 5 communities on the Cherokee Indian Reservation, an area of western North Carolina endemic for transmission of La Crosse (LAC) virus, to determine the potential for peridomestic mosquito breeding, the relative abundance of mosquito species, an...
Steenhof, Karen; Kochert, Michael N.; Carpenter, L.B.; Lehman, Robert N.
1999-01-01
We studied a nesting population of Prairie Falcons (Falco mexicanus) in the Snake River Birds of Prey National Conservation Area (NCA) from 1974-1997 to identify factors that influence abundance and reproduction. Our sampling period included two major droughts and associated crashes in Townsend's ground squirrel (Spermophilus townsendii) populations. The number of Prairie Falcon pairs found on long-term survey segments declined significantly from 1976-1997. Early declines were most severe at the eastern end of the NCA, where fires and agriculture have changed native shrubsteppe habitat. More recent declines occurred in the portion of canyon near the Orchard Training Area (OTA), where the Idaho Army National Guard conducts artillery firing and tank maneuvers. Overall Prairie Falcon reproductive rates were tied closely to annual indexes of ground squirrel abundance, but precipitation before and during the breeding season was related inversely to some measures of reproduction. Most reproductive parameters showed no significant trends over time, but during the 1990s, nesting success and productivity were lower in the stretch of canyon near the OTA than in adjacent areas. Extensive shrub loss, by itself, did not explain the pattern of declines in abundance and reproduction that we observed. Recent military training activities likely have interacted with fire and livestock grazing to create less than favorable foraging opportunities for Prairie Falcons in a large part of the NCA. To maintain Prairie Falcon populations in the NCA, managers should suppress wildfires, restore native plant communities, and regulate potentially incompatible land uses.
Changes in transcript abundance relating to colony collapse disorder in honey bees (Apis mellifera).
Johnson, Reed M; Evans, Jay D; Robinson, Gene E; Berenbaum, May R
2009-09-01
Colony collapse disorder (CCD) is a mysterious disappearance of honey bees that has beset beekeepers in the United States since late 2006. Pathogens and other environmental stresses, including pesticides, have been linked to CCD, but a causal relationship has not yet been demonstrated. Because the gut acts as a primary interface between the honey bee and its environment as a site of entry for pathogens and toxins, we used whole-genome microarrays to compare gene expression between guts of bees from CCD colonies originating on both the east and west coasts of the United States and guts of bees from healthy colonies sampled before the emergence of CCD. Considerable variation in gene expression was associated with the geographical origin of bees, but a consensus list of 65 transcripts was identified as potential markers for CCD status. Overall, elevated expression of pesticide response genes was not observed. Genes involved in immune response showed no clear trend in expression pattern despite the increased prevalence of viruses and other pathogens in CCD colonies. Microarray analysis revealed unusual ribosomal RNA fragments that were conspicuously more abundant in the guts of CCD bees. The presence of these fragments may be a possible consequence of picorna-like viral infection, including deformed wing virus and Israeli acute paralysis virus, and may be related to arrested translation. Ribosomal fragment abundance and presence of multiple viruses may prove to be useful diagnostic markers for colonies afflicted with CCD.
Changes in transcript abundance relating to colony collapse disorder in honey bees (Apis mellifera)
Johnson, Reed M.; Evans, Jay D.; Robinson, Gene E.; Berenbaum, May R.
2009-01-01
Colony collapse disorder (CCD) is a mysterious disappearance of honey bees that has beset beekeepers in the United States since late 2006. Pathogens and other environmental stresses, including pesticides, have been linked to CCD, but a causal relationship has not yet been demonstrated. Because the gut acts as a primary interface between the honey bee and its environment as a site of entry for pathogens and toxins, we used whole-genome microarrays to compare gene expression between guts of bees from CCD colonies originating on both the east and west coasts of the United States and guts of bees from healthy colonies sampled before the emergence of CCD. Considerable variation in gene expression was associated with the geographical origin of bees, but a consensus list of 65 transcripts was identified as potential markers for CCD status. Overall, elevated expression of pesticide response genes was not observed. Genes involved in immune response showed no clear trend in expression pattern despite the increased prevalence of viruses and other pathogens in CCD colonies. Microarray analysis revealed unusual ribosomal RNA fragments that were conspicuously more abundant in the guts of CCD bees. The presence of these fragments may be a possible consequence of picorna-like viral infection, including deformed wing virus and Israeli acute paralysis virus, and may be related to arrested translation. Ribosomal fragment abundance and presence of multiple viruses may prove to be useful diagnostic markers for colonies afflicted with CCD. PMID:19706391
Carbon and nitrogen abundance determinations from transition layer lines. [giant stars
NASA Technical Reports Server (NTRS)
Boehm-Vitense, Erika; Mena-Werth, Jose
1988-01-01
For red giants a smooth increase in the nitrogen to carbon abundance ratio for increasing B-V as is expected for the first dredge up phase when the outer convection zone deepens is found. An average increase in the nitrogen to silicon ratio for B-V = 0.6 which goes back to almost solar values for cool giants with B - V approximately 1.0 is reported. It looks as if Si would be enriched for deeper mixing contrary to expectations from standard evolution theory.
Cadmium and Cadmium/Zinc Ratios and Tobacco-Related Morbidities
Richter, Patricia; Faroon, Obaid; Pappas, R. Steven
2017-01-01
Metals are one of five major categories of carcinogenic or toxic constituents in tobacco and tobacco smoke. Cadmium is highly volatile and a higher percentage of the total tobacco cadmium content is efficiently transferred to mainstream tobacco smoke than many other toxic metals in tobacco. Inhaled cadmium bioaccumulates in the lungs and is distributed beyond the lungs to other tissues, with a total body biological half-life of one to two decades. Chronic cadmium exposure through tobacco use elevates blood and urine cadmium concentrations. Cadmium is a carcinogen, and an inducer of proinflammatory immune responses. Elevated exposure to cadmium is associated with reduced pulmonary function, obstructive lung disease, bronchogenic carcinoma, cardiovascular diseases including myocardial infarction, peripheral arterial disease, prostate cancer, cervical cancer, pancreatic cancer, and various oral pathologies. Cadmium and zinc have a toxicologically inverse relationship. Zinc is an essential element and is reportedly antagonistic to some manifestations of cadmium toxicity. This review summarizes associations between blood, urine, and tissue cadmium concentrations with emphasis on cadmium exposure due to tobacco use and several disease states. Available data about zinc and cadmium/zinc ratios and tobacco-related diseases is summarized from studies reporting smoking status. Collectively, data suggest that blood, urine, and tissue cadmium and cadmium/zinc ratios are often significantly different between smokers and nonsmokers and they are also different in smokers for several diseases and cancers. Additional biomonitoring data such as blood or serum and urine zinc and cadmium levels and cadmium/zinc ratios in smokers may provide further insight into the development and progression of diseases of the lung, cardiovascular system, and possibly other organs. PMID:28961214
Cadmium and Cadmium/Zinc Ratios and Tobacco-Related Morbidities.
Richter, Patricia; Faroon, Obaid; Pappas, R Steven
2017-09-29
Metals are one of five major categories of carcinogenic or toxic constituents in tobacco and tobacco smoke. Cadmium is highly volatile and a higher percentage of the total tobacco cadmium content is efficiently transferred to mainstream tobacco smoke than many other toxic metals in tobacco. Inhaled cadmium bioaccumulates in the lungs and is distributed beyond the lungs to other tissues, with a total body biological half-life of one to two decades. Chronic cadmium exposure through tobacco use elevates blood and urine cadmium concentrations. Cadmium is a carcinogen, and an inducer of proinflammatory immune responses. Elevated exposure to cadmium is associated with reduced pulmonary function, obstructive lung disease, bronchogenic carcinoma, cardiovascular diseases including myocardial infarction, peripheral arterial disease, prostate cancer, cervical cancer, pancreatic cancer, and various oral pathologies. Cadmium and zinc have a toxicologically inverse relationship. Zinc is an essential element and is reportedly antagonistic to some manifestations of cadmium toxicity. This review summarizes associations between blood, urine, and tissue cadmium concentrations with emphasis on cadmium exposure due to tobacco use and several disease states. Available data about zinc and cadmium/zinc ratios and tobacco-related diseases is summarized from studies reporting smoking status. Collectively, data suggest that blood, urine, and tissue cadmium and cadmium/zinc ratios are often significantly different between smokers and nonsmokers and they are also different in smokers for several diseases and cancers. Additional biomonitoring data such as blood or serum and urine zinc and cadmium levels and cadmium/zinc ratios in smokers may provide further insight into the development and progression of diseases of the lung, cardiovascular system, and possibly other organs.
NASA Technical Reports Server (NTRS)
Chaffee, F. H., Jr.; White, R. E.
1982-01-01
Observations of interstellar absorption in the resonance doublet 7664, 7698 A of neutral potassium toward 188 early-type stars at a spectral resolution of 8 km/s are reported. The 7664 A line is successfully separated from nearly coincident telluric O2 absorption for all but a few of the 165 stars for which K I absorption is detected, making possible an abundance analysis by the doublet ratio method. The relationships between the potassium abundances and other atomic abundances, the abundance of molecular hydrogen, and interstellar reddening are investigated.
Photospheric carbon and oxygen abundances of F-G type stars in the Pleiades cluster*
NASA Astrophysics Data System (ADS)
Takeda, Yoichi; Hashimoto, Osamu; Honda, Satoshi
2017-02-01
In order to investigate the carbon-to-oxygen ratio of the young open cluster M 45 (Pleiades), the C and O abundances of 32 selected F-G type dwarfs (in the effective temperature range of Teff ˜ 5800-7600 K and projected rotational velocity range of vesin i ˜ 10-110 km s-1) belonging to this cluster were determined by applying the synthetic spectrum-fitting technique to C i 5380 and O i 6156-8 lines. The non-local thermodynamical equilibrium corrections for these C i and O i lines were found to be practically negligible (less than a few hundredths dex).The resulting C and O abundances (along with the Fe abundance) turned out nearly uniform without any systematic dependence upon Teff or vesin i. We found, however, in spite of almost solar Fe abundance ([Fe/H] ˜ 0), carbon turned out to be slightly subsolar ([C/H] ˜ -0.1) while that of oxygen was slightly supersolar ([O/H] ˜ +0.1). This leads to a conclusion that the [C/O] ratio was moderately subsolar (˜ -0.2) in the primordial gas from which these Pleiades stars were formed ˜ 120-130 Myr ago. Interestingly, similarly young B-type stars are reported to show just the same result ([C/O] ˜ -0.2), while rather aged (˜ 1-10 Gyr) field F-G stars of near-solar metallicity yield almost the solar value ([C/O] ˜ 0) on average. Such a difference in the C/O ratio between two star groups of distinctly different ages may be explained as a consequence of the orbit migration mechanism which Galactic stars may undergo over a long time.
CHEMICAL ABUNDANCES OF MEMBER STARS IN THE OPEN CLUSTER NGC 2632 (PRAESEPE)
DOE Office of Scientific and Technical Information (OSTI.GOV)
Yang, X. L.; Chen, Y. Q.; Zhao, G.
2015-11-15
Based on high-resolution, high signal-to-noise ratio spectra, we present abundances of 17 elements (Fe, O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Co, Ni, Y, Zr, Ba, La) for six stars (one Am star, one F dwarf star, and four GK giant stars) and radial velocities for 18 proper-motion selected member stars in the open cluster NGC 2632. In the Am star, s-process elements Y and Ba are clearly overabundant, which may be considered as an indicator of a peculiar Am star. The average [Fe/H] is 0.16 ± 0.06 from four GK giant member stars, which is similarmore » to that of solar-type stars in the literature. As compared with dwarf stars, significant overabundances are found for Na, Mg, and Ba elements in our giant stars, which can be explained by the evolutionary effect. We also detect a star-to-star scatter of [Na/Fe] ratios among four giants which locate approximately at the same position in the CMD. Finally, we perform an analysis on the possible connection between the abundance and spatial structure of NGC 2632, but we find no inhomogeneous abundance among different clumps of stars in this cluster based on our limited sample.« less
Relative ratios of collagen composition of periarticular tissue of joints of the upper limb.
Cheah, A; Harris, A; Le, W; Huang, Y; Yao, J
2017-07-01
We investigated the relative ratios of collagen composition of periarticular tissue of the elbow, wrist, metacarpophalangeal, proximal and distal interphalangeal joints. Periarticulat tissue, which we defined as the ligaments, palmar plate and capsule, was harvested from ten fresh-frozen cadaveric upper limbs, yielding 50 samples. The mean paired differences (95% confidence interval) of the relative ratios of collagen between the five different joints were estimated using mRNA expression of collagen in the periarticular tissue. We found that the relative collagen composition of the elbow was not significantly different to that of the proximal interphalangeal joint, nor between the proximal interphalangeal joint and distal interphalangeal joint, whereas the differences in collagen composition between all the other paired comparisons of the joints had confidence intervals that did not include zero.
Herpetofaunal species composition and relative abundance among three New England forest types
Richard M. DeGraaf; Deborah D. Rudis
1990-01-01
Drift fences and pitfall traps captured > 2000 reptiles and amphibians during 2 years; the most common species were wood frog (Rana sylvatica), American toad (Bufo americanus), and redback salamander (Plethodon cinereus). There were differences in species abundances among streamside and upland...
NASA Astrophysics Data System (ADS)
Sneden, Christopher; Kraft, Robert P.; Guhathakurta, Puragra; Peterson, Ruth C.; Fulbright, Jon P.
2004-04-01
relative contribution of rare to abundant isotopes of Mg. This points to a scenario in which these abundance ratios arose in the ejected material of 3-6 Msolar cluster stars, material that was then used to form the atmospheres of the presently evolving low-mass cluster stars. It also suggests that the low oxygen abundance seen among the most evolved M13 giants arose in hot bottom O-to-N processing in these same intermediate-mass cluster stars. Thus, mixing is required by the dependence of some abundance ratios on luminosity, but an earlier nucleosynthesis process in a hotter environment than giants or main-sequence stars is required by the variations previously seen in stars near the main sequence. The nature and the site of the earlier process is constrained but not pinpointed by the observed Mg isotopic ratio. Based on data obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.
NASA Astrophysics Data System (ADS)
Youngbluth, M.; Sørnes, T.; Hosia, A.; Stemmann, L.
2008-01-01
Fourteen dives were conducted with the ROVs Aglantha and Bathysaurus to depths of 2335 m along the Mid-Atlantic Ridge (42∘52'- 53∘17'N). The most frequently observed gelatinous fauna in order of overall abundance included medusae, ctenophores, siphonophores, appendicularians, and tunicates. All of these animals, except the tunicates, occurred throughout the water column. Their relative abundances differed with depth and location. Identification to species was limited to easily recognized fauna because relatively few gelatinous animals were collected. Each group of gelatinous zooplankton tended to be most numerous in a region just south of the Charlie-Gibbs Fracture Zone. Medusae (mainly Aeginura grimaldii) were the most frequently encountered animals (up to 25 individuals per 100m3). On a vertical scale their abundance peaked from 550 to 800 m and these maxima were consistently within the SAIW and NACWe. In the NACW their densities were notably lower (up 2 individuals per 100m3) and the majority of the population was deeper, ranging from 800 to 1050 m. Ctenophores (mainly Bathocyroe fosteri) were most prominent (as many as 27 individuals per 100m3) in a zone from 300 to 600 m in the NACWe. Appendicularians (primarily oikopleurids) had a broader vertical distribution in all water masses, mainly from 450 to 1000 m. Up to 12 houses per 100m3 were noted in the NACWe, and these estimates are considered to be very conservative. Sorties near the sea floor (as deep as 2100 m) indicated these detritivores were a prominent component (up to 5 houses per 100m3) of the epibenthic macrozooplankton. Siphonophores (mostly calycophorans) reached densities of about 14 colonies per 100m3 in the NACWe and occurred mainly from 300 to 600 m, at most locations. Tunicates (salps and doliolids) were patchy in their distribution and infrequently observed. Salps were numerous (up to 3 solitary individuals per 100m3) at only one location (sta. 50) near the surface. Deep-living doliolids
Comparison of meiofaunal abundance in two mangrove wetlands in Tong'an Bay, Xiamen, China
NASA Astrophysics Data System (ADS)
Zhou, Xiping; Cai, Lizhe; Fu, Sujing
2015-10-01
To compare meiofaunal community in the two mangrove wetlands in Tong'an Bay, Xiamen, China, and probe the response of meiofauna to high organic matter, sampling was carried out in Fenglin and Xiang'an mangrove wetlands in the bay. The results showed that the Ne/Co ratio (nematode to benthic copepod) and organic matter in Fenglin mangrove wetland were higher than those in Xiang'an mangrove wetland. The meiofaunal abundance in Fenglin mangrove was all lower than that in Xiang'an mangrove wetland in summer, autumn and spring, while the meiofaunal abundance in Fenglin mangrove was higher than that in Xiang'an mangrove wetland in winter. Two-way ANOVA results showed that the meiofaunal abundance and nematode abundance were significantly different between regions, seasons and region×season. With all the results in the present study, we confirmed that the positive response of meiofaunal and nematode abundance were only detected for medium organic matter contents according to the Xiang'an wetland's level, and that the distribution of meiofaunal abundance would be influenced by sand content. Higher copepod abundance and lower N/C value usually suggest better environmental quality.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Balatsoukas, Ioannis; Kourkoumelis, Nikolaos; Tzaphlidou, Margaret
The Ca/P ratio of normal cortical and trabecular rat bone was measured by Auger electron spectroscopy (AES). Semiquantitative analysis was carried out using ratio techniques to draw conclusions on how age, sex and bone site affect the relative composition of calcium and phosphorus. Results show that Ca/P ratio is not sex dependent; quite the opposite, bone sites exhibit variations in elemental stoichiometry where femoral sections demonstrate higher Ca/P ratio than rear and front tibias. Age-related changes are more distinct for cortical bone in comparison with the trabecular bone. The latter's Ca/P ratio remains unaffected from all the parameters under study.more » This study confirms that AES is able to successfully quantify bone mineral main elements when certain critical points, related to the experimental conditions, are addressed effectively.« less
Mangudo, C; Aparicio, J P; Rossi, G C; Gleiser, R M
2018-04-01
Water-holding tree holes are main larval habitats for many pathogen vectors, especially mosquitoes (Diptera: Culicidae). Along 3 years, the diversity and composition of mosquito species in tree holes of two neighbouring but completely different environments, a city and its adjacent forest, were compared using generalized linear mixed models, PERMANOVA, SIMPER and species association indexes. The city area (Northwest Argentina) is highly relevant epidemiologically due to the presence of Aedes aegypti L. (main dengue vector) and occurrence of dengue outbreaks; the Yungas rainforests are highly biologically diverse. In total seven mosquito species were recorded, in descending order of abundance: Ae. aegypti, Haemagogus spegazzinii Brèthes, Sabethes purpureus (Theobald), Toxorhynchites guadeloupensis Dyar and Knab, Aedes terrens Walker, Haemagogus leucocelaenus Dyar & Shannon and Sabethes petrocchiae (Shannon and Del Ponte). The seven mosquito species were recorded in both city sites and forested areas; however, their mosquito communities significantly diverged because of marked differences in the frequency and relative abundance of some species: Tx. guadeloupensis and Ae. aegypti were significantly more abundant in forest and urban areas, respectively. Positive significant associations were detected between Ae. aegypti, Hg. spegazzinii and Hg. leucocelaenus. The combined presence of Ae. aegypti, Haemagogus and Sabethes in the area also highlight a potential risk of yellow fever epidemics. Overall results show an impoverished tree hole mosquito fauna in urban environments, reflecting negative effects of urbanization on mosquito diversity.
Complexity on Small Scales. III. Iron and α Element Abundances in the Carina Dwarf Spheroidal Galaxy
NASA Astrophysics Data System (ADS)
Koch, Andreas; Grebel, Eva K.; Gilmore, Gerard F.; Wyse, Rosemary F. G.; Kleyna, Jan T.; Harbeck, Daniel R.; Wilkinson, Mark I.; Wyn Evans, N.
2008-04-01
We have obtained high-resolution spectroscopy of ten red giants in the Carina dwarf spheroidal (dSph) galaxy with the ultraviolet and visual echelle spectrograph at the European Southern Observatory Very Large Telescope in order to study the detailed chemical evolution of this Galactic satellite. Here we present the abundances of O, Na, Mg, Si, Ca, Ti, and Fe. By comparison of the derived iron abundances [Fe/H] with metallicities based on the well-established calcium triplet (CaT) calibration, [Fe/H]CaT, we show that the empirical CaT technique yields good agreement with the high-resolution data for [Fe/H] gsim 2 dex, but tends to deviate from these data at lower metallicities. With [Fe/H] ~ 1.7 dex the mean iron abundance of our targets is fully consistent with the peak metallicity of Carina as derived from medium-resolution spectroscopy and previous photometric studies, all calibrated onto iron via Galactic globular cluster scales. We identify two metal-poor stars with iron abundances of 2.72 and 2.50 dex. These stars are found to have enhanced [α/Fe] ratios similar to the elemental ratios of stars in the Milky Way halo. In this context, it is conceivable that the moderately metal-poor halo stars may originate from an early dSph accretion event. The bulk of the Carina red giants exhibit a depletion in the [α/Fe] abundance ratios with respect to the Galactic halo at a given metallicity. One of our targets with a moderately low [Fe/H] of 1.5 dex is considerably depleted in almost all of the α-elements by ~0.5 dex compared to the solar values. Such low values of the ratio of α-elements to iron can be produced by stochastical fluctuations in terms of an incomplete mixing of single type Ia and type II supernova (SN) events into the interstellar medium. Moreover, the system's slow star-formation (SF) rate grants sufficient time for SNe I to occur. Our derived chemical element ratios are consistent with the episodic and extended SF in Carina previously derived from
Peng, Chu; Wang, He; Jiang, Yingying; Yang, Jinhua; Lai, Hangxian; Wei, Xiaomin
2018-05-10
Thus far, no studies have investigated the soil microbial diversity over an elevational gradient in Taibai Mountain, the central massif of the Qinling Mountain Range. Here, we used Illumina sequencing and quantitative PCR of the 16S rRNA gene to assess the diversity and abundance of bacterial communities along an elevational gradient in representative vegetation soils in Taibai Mountain. We identified the soil, climate, and vegetation factors driving the variations in soil bacterial community structure by Pearson correlation and redundancy analysis. We also evaluated the potential for antibiotic discovery by quantitative PCR of the PKS-I, PKS-II, and NRPS genes from Actinobacteria. The results showed that soil bacterial alpha diversity increased first and then decreased with an elevational rise in both the northern and southern slopes of Taibai Mountain. The bacterial abundance was significantly correlated with soil organic matter and nitrate nitrogen. The average relative abundance of Actinobacteria in Taibai Mountain was markedly higher than those in other mountain forest soils. The absolute abundance of PKS and NPRS gene was significantly higher in the tested soils compared with the gene copy numbers reported in tropical urban soils. Taibai Mountain is rich in actinomycete resources and has great potential for antibiotic excavation.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Sameshima, H.; Yoshii, Y.; Kawara, K., E-mail: sameshima@cc.kyoto-su.ac.jp
2017-01-10
We present an analysis of Mg ii λ 2798 and Fe ii UV emission lines for archival Sloan Digital Sky Survey (SDSS) quasars to explore the diagnostics of the magnesium-to-iron abundance ratio in a broad-line region cloud. Our sample consists of 17,432 quasars selected from the SDSS Data Release 7 with a redshift range of 0.72 < z < 1.63. A strong anticorrelation between the Mg ii equivalent width (EW) and the Eddington ratio is found, while only a weak positive correlation is found between the Fe ii EW and the Eddington ratio. To investigate the origin of these differing behaviors ofmore » Mg ii and Fe ii emission lines, we perform photoionization calculations using the Cloudy code, where constraints from recent reverberation mapping studies are considered. We find from calculations that (1) Mg ii and Fe ii emission lines are created at different regions in a photoionized cloud, and (2) their EW correlations with the Eddington ratio can be explained by just changing the cloud gas density. These results indicate that the Mg ii/Fe ii flux ratio, which has been used as a first-order proxy for the Mg/Fe abundance ratio in chemical evolution studies with quasar emission lines, depends largely on the cloud gas density. By correcting this density dependence, we propose new diagnostics of the Mg/Fe abundance ratio for a broad-line region cloud. In comparing the derived Mg/Fe abundance ratios with chemical evolution models, we suggest that α -enrichment by mass loss from metal-poor intermediate-mass stars occurred at z ∼ 2 or earlier.« less
NASA Astrophysics Data System (ADS)
Nelson, D. M.; Hu, F.; Pearson, A.
2007-12-01
C3 and C4 grasses have distinct influences on major biogeochemical processes and unique responses to important environmental controls. Difficulties in distinguishing between these two functional groups of grasses have hindered paleoecological studies of grass-dominated ecosystems. We recently developed a technique to analyze the stable carbon isotope composition of individual grass-pollen grains using a spooling- wire microcombustion device interfaced with an isotope-ratio mass spectrometer (Nelson et al. 2007). This technique holds promise for improving C3 and C4 grass reconstructions. It requires ~90% fewer grains than typical methods and avoids assumptions associated with mixing models. However, our previous work was based on known C3 and C4 grasses from herbarium specimens and field collections and the technique had not been test using geological samples. To test the ability of this technique to reproduce the abundance of C3 and C4 grasses on the landscape, we measured δ13C values of >1500 individual grains of grass pollen isolated from the surface sediments of 10 North American lakes that span a large gradient of C3 and C4 grass abundance. Results indicate a strong positive correlation (r=0.94) between % C4-grass pollen (derived from classifying δ13C values from single grains as C3 and C4) and the literature-reported abundance of C4 grasses on the landscape. However, the measured % C4-grass pollen shows some deviation from the actual abundance at sites with high proportions of C4 grasses. This is likely caused by uncertainty in the magnitude, composition, and variability of the analytical blank associated with these measurements. Correcting for this deviation using regression analysis improves the estimation of the abundance of C4 grasses on the landscape. Comparison of the % C4-grass pollen with C/N and δ13C measurements of total organic matter in the same lake-sediment samples illustrates the distinct advantage of grass-pollen δ13C as a proxy for
When should we expect microbial phenotypic traits to predict microbial abundances?
Fox, Jeremy W
2012-01-01
Species' phenotypic traits may predict their relative abundances. Intuitively, this is because locally abundant species have traits making them well-adapted to local abiotic and biotic conditions, while locally rare species are not as well-adapted. But this intuition may not be valid. If competing species vary in how well-adapted they are to local conditions, why doesn't the best-adapted species simply exclude the others entirely? But conversely, if species exhibit niche differences that allow them to coexist, then by definition there is no single best adapted species. Rather, demographic rates depend on species' relative abundances, so that phenotypic traits conferring high adaptedness do not necessarily confer high abundance. I illustrate these points using a simple theoretical model incorporating adjustable levels of "adaptedness" and "niche differences." Even very small niche differences can weaken or even reverse the expected correlation between adaptive traits and abundance. Conversely, adaptive traits confer high abundance when niche differences are very strong. Future work should be directed toward understanding the link between phenotypic traits and frequency-dependence of demographic rates.
Delgado, Dolores; Alonso-Blanco, Carlos; Fenoll, Carmen; Mena, Montaña
2011-01-01
Background and Aims Current understanding of stomatal development in Arabidopsis thaliana is based on mutations producing aberrant, often lethal phenotypes. The aim was to discover if naturally occurring viable phenotypes would be useful for studying stomatal development in a species that enables further molecular analysis. Methods Natural variation in stomatal abundance of A. thaliana was explored in two collections comprising 62 wild accessions by surveying adaxial epidermal cell-type proportion (stomatal index) and density (stomatal and pavement cell density) traits in cotyledons and first leaves. Organ size variation was studied in a subset of accessions. For all traits, maternal effects derived from different laboratory environments were evaluated. In four selected accessions, distinct stomatal initiation processes were quantitatively analysed. Key Results and Conclusions Substantial genetic variation was found for all six stomatal abundance-related traits, which were weakly or not affected by laboratory maternal environments. Correlation analyses revealed overall relationships among all traits. Within each organ, stomatal density highly correlated with the other traits, suggesting common genetic bases. Each trait correlated between organs, supporting supra-organ control of stomatal abundance. Clustering analyses identified accessions with uncommon phenotypic patterns, suggesting differences among genetic programmes controlling the various traits. Variation was also found in organ size, which negatively correlated with cell densities in both organs and with stomatal index in the cotyledon. Relative proportions of primary and satellite lineages varied among the accessions analysed, indicating that distinct developmental components contribute to natural diversity in stomatal abundance. Accessions with similar stomatal indices showed different lineage class ratios, revealing hidden developmental phenotypes and showing that genetic determinants of primary and
ISM abundances and history: a 3D, solar neighborhood view
NASA Astrophysics Data System (ADS)
Lallement, R.; Vergely, J.-L.; Puspitarini, L.
For observational reasons, the solar neighborhood is particularly suitable for the study of the multi-phase interstellar (IS) medium and the search for traces of its temporal evolution. On the other hand, by a number of aspects it seems to be a peculiar region. We use recent 3D maps of the IS dust based on color excess data as well as former maps of the gas to illustrate how such maps can be used to shed additional light on the specificity of the local medium, its history and abundance pattern. 3D maps reveal a gigantic cavity located in the third quadrant and connected to the Local Bubble, the latter itself running into an elongated cavity toward l≃ 70°. Most nearby cloud complexes of the so-called Gould belt but also more distant clouds seem to border a large fraction of this entire structure. The IS medium with the large cavity appears ionized and dust-poor, as deduced from ionized calcium and neutral sodium to dust ratios. The geometry favors the proposed scenario of Gould belt-Local Arm formation through the braking of a supercloud by interaction with a spiral density wave \\citep{olano01}. The highly variable D/H ratio in the nearby IS gas may also be spatially related to the global structure. We speculate about potential consequences of the supercloud encounter and dust-gas decoupling during its braking, in particular the formation of strong inhomogeneities in both the dust to gas abundance ratio and the dust characteristics: (i) during the ≃ 500 Myrs prior to the collision, dust within the supercloud may have been gradually, strongly enriched in D due to an absence of strong stellar formation and preferential adsorption of D \\citep{jura82,draine03} ; (ii) during its interaction with the Plane and the braking dust-rich and dust-poor regions may have formed due to differential gas drag, the dust being more concentrated in the dense areas; strong radiation pressure from OB associations at the boundary of the left-behind giant cavity may have also helped
Isotopic Ratios in Nitrile Species on Titan using ALMA
NASA Astrophysics Data System (ADS)
Molter, Edward; Nixon, Conor; Cordiner, Martin; Serigano, Joseph; Irwin, Patrick; Teanby, Nicholas; Charnley, Steven; Lindeberg, Johan
2016-06-01
The atmosphere of Titan is primarily composed of molecular nitrogen (N2, ˜98%) and methane (CH4, ˜2%), but also hosts a myriad of trace organic species. Two of the simplest and most abundant of these are hydrogen cyanide (HCN) and cyanoacetylene (HC3N). The advent of ALMA provides the opportunity to observe rotational transitions in these molecules and their isotopologues with unprecendented sensitivity and spatial resolution. We searched through the ALMA archive for publicly available high-resolution observations of Titan as a flux calibrator source taken between April and July 2014; each integration lasted around 160 seconds. Using spectra of HCN and HC3N isotopologues found in these data, we derive vertical abundance profiles and determine the isotopic ratios 14N/15N and 12C/13C in these molecules. We also report the detection of a new HCN isotopologue on Titan, H13C6 15N, and use a high signal-to-noise spectrum of DCN to determine the D/H ratio in HCN on Titan for the first time. These isotopic ratios are leveraged to constrain the physical and chemical processes occurring in Titan's atmosphere.
Moreno, J E; Rubio-Palis, Y; Páez, E; Pérez, E; Sánchez, V
2007-12-01
A longitudinal entomological and epidemiological study was conducted in five localities of southern Venezuela between January 1999 and April 2000 to determine the abundance, biting behaviour and parity of anopheline mosquitoes (Diptera: Culicidae) in relation to climate variables and malaria incidence. A total of 3685 female anopheline mosquitoes, representing six species, were collected. The most abundant species were Anopheles marajoara Galvão & Damasceno (60.7%) and Anopheles darlingi Root (35.1%), which together represented 95.8% of the total anophelines collected. Abundance and species distribution varied by locality. Malaria prevalence varied from 12.5 to 21.4 cases per 1000 population. Transmission occurred throughout the year; the annual parasite index (API) for the study period was 813.0 cases per 1000 population, with a range of 71.6-2492 per 1000 population, depending on locality. Plasmodium vivax (Grassi & Feletti) (Coccidia: Plasmodiidae) accounted for 78.6% of cases, Plasmodium falciparum (Welch) for 21.4% and mixed infections (Pv+Pf) for < 0.1%. Anopheles marajoara and An. darlingi were more abundant during the rainy season (April-September). There was no significant correlation (P > 0.05) between mosquito abundance and rainfall. Correlations between malaria incidence by parasite species and mosquito abundance were not significant (P > 0.05). Monthly parous rates were similar for An. marajoara and An. darlingi throughout the year, with two peaks that coincided with the dry-rainy transition period and the period of less rain. Peaks in the incidence of malaria cases were observed 1 month after major peaks in biting rates of parous anophelines. Anopheles darlingi engages in biting activity throughout the night, with two minor peaks at 23.00-00.00 hours and 03.00-04.00 hours. Anopheles marajoara has a different pattern, with a biting peak at 19.00-21.00 hours and 76.6% of biting occurring before midnight. Although both vectors bite indoors and outdoors
Abundance and Distribution of Microbial Cells and Viruses in an Alluvial Aquifer
DOE Office of Scientific and Technical Information (OSTI.GOV)
Pan, Donald; Nolan, Jason; Williams, Kenneth H.
Viruses are the most abundant biological entity on Earth and their interactions with microbial communities are recognized to influence microbial ecology and impact biogeochemical cycling in various ecosystems. While the factors that control the distribution of viruses in surface aquatic environments are well-characterized, the abundance and distribution of continental subsurface viruses with respect to microbial abundance and biogeochemical parameters have not yet been established. In order to begin to understand the factors governing virus distribution in subsurface environments, we assessed microbial cell and virus abundance in groundwater concurrent with groundwater chemistry in a uranium impacted alluvial aquifer adjoining the Coloradomore » River near Rifle, CO. Virus abundance ranged from 8.0 × 10 4 to 1.0 × 10 6 mL -1 and exceeded cell abundance in all samples (cell abundance ranged from 5.8 × 10 4 to 6.1 × 10 5 mL -1). The virus to microbial cell ratio ranged from 1.1 to 8.1 and averaged 3.0 ± 1.6 with virus abundance most strongly correlated to cell abundance (Spearman's ρ = 0.73, p < 0.001). Both viruses and cells were positively correlated to dissolved organic carbon (DOC) with cells having a slightly stronger correlation (Spearman's ρ = 0.46, p < 0.05 and ρ = 0.54, p < 0.05; respectively). Groundwater uranium was also strongly correlated with DOC and virus and cell abundance (Spearman's ρ = 0.62, p < 0.05; ρ = 0.46, p < 0.05; and ρ = 0.50, p < 0.05; respectively). Together the data indicate that microbial cell and virus abundance are correlated to the geochemical conditions in the aquifer. As such local geochemical conditions likely control microbial host cell abundance which in turn controls viral abundance. Given the potential impacts of viral-mediated cell lysis such as liberation of labile organic matter from lysed cells and changes in microbial community structure, viral interactions with the microbiota should be considered in an
Abundance and Distribution of Microbial Cells and Viruses in an Alluvial Aquifer
Pan, Donald; Nolan, Jason; Williams, Kenneth H.; ...
2017-07-11
Viruses are the most abundant biological entity on Earth and their interactions with microbial communities are recognized to influence microbial ecology and impact biogeochemical cycling in various ecosystems. While the factors that control the distribution of viruses in surface aquatic environments are well-characterized, the abundance and distribution of continental subsurface viruses with respect to microbial abundance and biogeochemical parameters have not yet been established. In order to begin to understand the factors governing virus distribution in subsurface environments, we assessed microbial cell and virus abundance in groundwater concurrent with groundwater chemistry in a uranium impacted alluvial aquifer adjoining the Coloradomore » River near Rifle, CO. Virus abundance ranged from 8.0 × 10 4 to 1.0 × 10 6 mL -1 and exceeded cell abundance in all samples (cell abundance ranged from 5.8 × 10 4 to 6.1 × 10 5 mL -1). The virus to microbial cell ratio ranged from 1.1 to 8.1 and averaged 3.0 ± 1.6 with virus abundance most strongly correlated to cell abundance (Spearman's ρ = 0.73, p < 0.001). Both viruses and cells were positively correlated to dissolved organic carbon (DOC) with cells having a slightly stronger correlation (Spearman's ρ = 0.46, p < 0.05 and ρ = 0.54, p < 0.05; respectively). Groundwater uranium was also strongly correlated with DOC and virus and cell abundance (Spearman's ρ = 0.62, p < 0.05; ρ = 0.46, p < 0.05; and ρ = 0.50, p < 0.05; respectively). Together the data indicate that microbial cell and virus abundance are correlated to the geochemical conditions in the aquifer. As such local geochemical conditions likely control microbial host cell abundance which in turn controls viral abundance. Given the potential impacts of viral-mediated cell lysis such as liberation of labile organic matter from lysed cells and changes in microbial community structure, viral interactions with the microbiota should be considered in an
Kharitonov, S P; Volkov, A E; Willems, F; van Kleef, H; Klaassen, R H G; Nowak, D J; Nowak, A I; Bublichenko, A G
2008-01-01
Brant goose colonies around snowy owl nests have been studied near Meduza Bay (73 degrees 21' N, 80 degrees 32' E) and in the lower reaches of the Uboinaya River (73 degrees 37' N, 82 degrees 10' E), the northwestern Taimyr Peninsula, from 1999 to 2006. All brant nests within 680 m from an owl nest have been regarded as an individual colony. The results show that the area of the colony is always larger than the guarded area around the owl nest. In years of high abundance of lemmings, brant geese nest generally closer to the owl nest than in years of high abundance. When arctic foxes are abundant, however, brant geese nest significantly closer to owls than when the foxes are scarce, irrespective of lemming abundance. The mechanism of brant colony formation around owl nests is based on a number of stimuli.
Abundance and productivity of birds over an elevational gradient
Kathryn L. Purcell
2002-01-01
This study is investigating the abundance and productivity of birds breeding in four forest types over an elevational gradient in conifer forests of the southern Sierra Nevada of California to identify the most productive habitats for each species, and to examine elevational shifts in abundance, especially as they relate to temperature and precipitation. Species...
Cooper, W. Rodney; Garczynski, Stephen F.; Horton, David R.
2015-01-01
Carsonella ruddii (Gamma Proteobacterium) is an obligate bacterial endosymbiont of psyllids that produces essential amino acids that are lacking in the insect’s diet. Accurate estimations of Carsonella populations are important to studies of Carsonella-psyllid interactions and to developing ways to target Carsonella for control of psyllid pests including pear psylla, Cacopsylla pyricola (Förster) (Hemiptera: Psyllidae) and potato psyllid, Bactericera cockerelli (Šulc) (Hemiptera: Triozidae). We used two methods, namely fluorescence in situ hybridization and quantitative polymerase chain reaction (qPCR), to estimate relative abundance of Carsonella in bacteriocytes and whole bodies of psyllids, respectively. Using these two methods, we compared Carsonella populations between female and male insects. Estimations using fluorescence in situ hybridization indicated that Carsonella was more abundant in bacteriocytes of female C. pyricola than in those of males, but Carsonella abundance in bacteriocytes did not differ between sexes of B. cockerelli. Analyses by qPCR using whole-body specimens indicated Carsonella was more abundant in females than in males of both psyllids. Neither fluorescence in situ hybridization nor qPCR indicated that Carsonella populations differed in abundance among adults of different ages (0–3 wk after adult eclosion). Using fluorescence in situ hybridization, Carsonella was observed in ovarioles of newly emerged females and formed an aggregation in the posterior end of mature oocytes. Results of our study indicate that female psyllids harbor greater populations of Carsonella than do males and that sex should be controlled for in studies which require estimations of Carsonella populations. PMID:26056318
Coronal abundances and their variation
NASA Technical Reports Server (NTRS)
Saba, Julia L. R.
1994-01-01
This contract supports the investigation of elemental abundances in the solar corona, principally through analysis of high-resolution software X-ray spectra from the Flat Crystal Spectrometer on NASA's Solar Maximum Mission. The goals of the study are a characterization of the mean values of relative abundances of elements accessible in the FCS data, and information on the extent and circumstances of their variability. This report is a summation of the data analysis and reporting activities which occurred since the last report, submitted two months early, in April 1994, to facilitate evaluation of the first year's progress for contract renewal. Hence this report covers the period 15 April 1994 - 15 December 1994. A list of publications resulting from this research is included.
New Constraints on the Abundance of 60Fe in the Early Solar System
DOE Office of Scientific and Technical Information (OSTI.GOV)
Trappitsch, Reto; Boehnke, Patrick; Stephan, Thomas
Establishing the abundance of the extinct radionuclide 60Fe (half-life 2.62 Ma) in the early solar system is important for understanding the astrophysical context of solar system formation. While bulk measurements of early solar system phases show a low abundance consistent with galactic background, some in situ measurements by secondary ion mass spectrometry (SIMS) imply a higher abundance, which would require injection from a nearby supernova (SN). In this paper, we present in situ nickel isotopic analyses by resonance ionization mass spectrometry (RIMS) in a chondrule from the primitive meteorite Semarkona (LL3.00). The same chondrule had been previously analyzed by SIMS.more » Despite improved precision compared to SIMS, the RIMS nickel isotopic data do not reveal any resolved excesses of 60Ni that could be unambiguously ascribed to in situ 60Fe decay. Linear regression of 60Ni/ 58Ni versus 56Fe/ 58Ni yields an initial 60Fe/ 56Fe ratio for this chondrule of (3.8 ± 6.9) × 10 -8, which is consistent with both the low initial value found by bulk measurements and the low end of the range of initial ratios inferred from some in situ work. The same regression also gives a solar initial 60Ni/ 58Ni ratio, which shows that this sample was not disturbed by nickel mobilization, thus agreeing with a low initial 60Fe/ 56Fe ratio. These findings agree with a re-evaluation of previous SIMS measurements of the same sample. Finally, supernova injection of 60Fe into the solar system or its parental cloud material is therefore not necessary to account for the measured solar system's initial amount of 60Fe.« less
New Constraints on the Abundance of 60Fe in the Early Solar System
Trappitsch, Reto; Boehnke, Patrick; Stephan, Thomas; ...
2018-04-19
Establishing the abundance of the extinct radionuclide 60Fe (half-life 2.62 Ma) in the early solar system is important for understanding the astrophysical context of solar system formation. While bulk measurements of early solar system phases show a low abundance consistent with galactic background, some in situ measurements by secondary ion mass spectrometry (SIMS) imply a higher abundance, which would require injection from a nearby supernova (SN). In this paper, we present in situ nickel isotopic analyses by resonance ionization mass spectrometry (RIMS) in a chondrule from the primitive meteorite Semarkona (LL3.00). The same chondrule had been previously analyzed by SIMS.more » Despite improved precision compared to SIMS, the RIMS nickel isotopic data do not reveal any resolved excesses of 60Ni that could be unambiguously ascribed to in situ 60Fe decay. Linear regression of 60Ni/ 58Ni versus 56Fe/ 58Ni yields an initial 60Fe/ 56Fe ratio for this chondrule of (3.8 ± 6.9) × 10 -8, which is consistent with both the low initial value found by bulk measurements and the low end of the range of initial ratios inferred from some in situ work. The same regression also gives a solar initial 60Ni/ 58Ni ratio, which shows that this sample was not disturbed by nickel mobilization, thus agreeing with a low initial 60Fe/ 56Fe ratio. These findings agree with a re-evaluation of previous SIMS measurements of the same sample. Finally, supernova injection of 60Fe into the solar system or its parental cloud material is therefore not necessary to account for the measured solar system's initial amount of 60Fe.« less
NASA Astrophysics Data System (ADS)
King, Jeremy R.; Hiltgen, Daniel D.
1996-12-01
We present observations of the 6300 Å [O I] spectral region in two cool Hyades dwarfs, vB 79 and vB 25. We derive a mean iron abundance, [Fe/H]˜+0.11, in good agreement with recent analyses of F and G Hyades dwarfs. The O abundance derived from spectrum synthesis, [O/H]˜+0.15, is between the values deduced by Garcia Lopez et al. (1993, ApJ, 412, 173; [O/H]=-0.05 to -0.10) and King (1993, Ph. D. Dissertation, University of Hawaii; [O/H]=+0.26), who employed the 7774 Å O I triplet in hotter Hyades dwarfs. An accounting of differences between these two 7774 Å analyses is given. Our [O I]-based determination suggests the Hyades O abundance itself is super-solar, though [O/Fe]˜0.0; however, systematic errors as large as 0.10-0.15 dex cannot be ruled out. The Hyades giants show an unexpected ˜0.23 dex O deficit relative to our dwarf value. While some suggestive evidence for non-standard nuclear processing and mixing in the Hyades giants may exist, we find it unconvincing. Rather, model atmosphere deficiencies or [O I] -region blending features that are still unrecognized by laboratory and theoretical efforts may contribute to the giant-dwarf O discrepancy. Finally, our high O abundance is marginally consistent with values claimed to provide a solution to the Hyades Li problem from standard stellar models. However, it is not clear that these models do in fact reproduce the extant Li data. Our Li abundance upper limit for vB 25 is at least 0.5 dex lower than the abundances of two tidally locked binaries of similar Teff. Standard stellar models of uniform composition and age are not able to reproduce such scatter in Li.
Yao, Huaiying; Gao, Yangmei; Nicol, Graeme W.; Campbell, Colin D.; Prosser, James I.; Zhang, Limei; Han, Wenyan; Singh, Brajesh K.
2011-01-01
Ammonia oxidation is the first and rate-limiting step of nitrification and is performed by both ammonia-oxidizing archaea (AOA) and bacteria (AOB). However, the environmental drivers controlling the abundance, composition, and activity of AOA and AOB communities are not well characterized, and the relative importance of these two groups in soil nitrification is still debated. Chinese tea orchard soils provide an excellent system for investigating the long-term effects of low pH and nitrogen fertilization strategies. AOA and AOB abundance and community composition were therefore investigated in tea soils and adjacent pine forest soils, using quantitative PCR (qPCR), terminal restriction fragment length polymorphism (T-RFLP) and sequence analysis of respective ammonia monooxygenase (amoA) genes. There was strong evidence that soil pH was an important factor controlling AOB but not AOA abundance, and the ratio of AOA to AOB amoA gene abundance increased with decreasing soil pH in the tea orchard soils. In contrast, T-RFLP analysis suggested that soil pH was a key explanatory variable for both AOA and AOB community structure, but a significant relationship between community abundance and nitrification potential was observed only for AOA. High potential nitrification rates indicated that nitrification was mainly driven by AOA in these acidic soils. Dominant AOA amoA sequences in the highly acidic tea soils were all placed within a specific clade, and one AOA genotype appears to be well adapted to growth in highly acidic soils. Specific AOA and AOB populations dominated in soils at particular pH values and N content, suggesting adaptation to specific niches. PMID:21571885
Sunspots, Starspots, and Elemental Abundances
NASA Astrophysics Data System (ADS)
Doschek, George A.; Warren, Harry P.
2017-08-01
The composition of plasma in solar and stellar atmospheres is not fixed, but varies from feature to feature. These variations are organized by the First Ionization Potential (FIP) of the element. Solar measurements often indicate that low FIP elements (< 10eV, such as Fe, Si, Mg) are enriched by factors of 3-4 in the corona relative to high FIP elements (>10 eV, such as C, N, O, Ar, He) compared to abundances in the photosphere. Stellar observations have also shown similar enrichments. An inverse FIP effect, where the low FIP elements are depleted, has been observed in stellar coronae of stars believed to have large starspots in their photospheres. The abundances are important for determining radiative loss rates in models, tracing the origin of the slow solar wind, and for understanding wave propagation in the chromosphere and corona. Recently, inverse FIP effects have been discovered in the Sun (Doschek, Warren, & Feldman 2015, ApJ, 808, L7) from spectra obtained by the Extreme-ultraviolet Imaging Spectrometer (EIS) on the Hinode spacecraft. The inverse FIP regions seem always to be near sunspots and cover only a very small area (characteristic length = a few arcseconds). However, in pursuing the search for inverse FIP regions, we have found that in some sunspot groups the coronal abundance at a temperature of 3-4 MK can be near photospheric over much larger areas of the sun near the sunspots (e.g., 6,000 arcsec2). Also, sometimes the abundances at 3-4 MK are in between coronal and photospheric values. This can occur in small areas of an active region. It is predicted (Laming 2015, Sol. Phys., 12, 2) that the FIP effect should be highly variable in the corona. Several examples of coronal abundance variations are presented. Our work indicates that a comprehensive re-investigation of solar abundances is highly desirable. This work is supported by a NASA Hinode grant.
Gylling, Björn; Myte, Robin; Ulvik, Arve; Ueland, Per M; Midttun, Øivind; Schneede, Jörn; Hallmans, Göran; Häggström, Jenny; Johansson, Ingegerd; Van Guelpen, Bethany; Palmqvist, Richard
2018-05-22
One-carbon metabolism biomarkers are easily measured in plasma, but analyzing them one at a time in relation to disease does not take into account the interdependence of the many factors involved. The relative dynamics of major one-carbon metabolism branches can be assessed by relating the functional B-vitamin marker total homocysteine (tHcy) to transsulfuration (total cysteine) and methylation (creatinine) outputs. We validated the ratios of tHcy to total cysteine (Hcy:Cys), tHcy to creatinine (Hcy:Cre), and tHcy to cysteine to creatinine (Hcy:Cys:Cre) as functional markers of B-vitamin status. We also calculated the associations of these ratios to colorectal cancer (CRC) risk. Furthermore, the relative contribution of potential confounders to the variance of the ratio-based B-vitamin markers was calculated by linear regression in a nested case-control study of 613 CRC cases and 1190 matched controls. Total B-vitamin status was represented by a summary score comprising Z-standardized plasma concentrations of folate, cobalamin, betaine, pyridoxal 5'-phosphate, and riboflavin. Associations with CRC risk were estimated using conditional logistic regression. We found that the ratio-based B-vitamin markers all outperformed tHcy as markers of total B-vitamin status, in both CRC cases and controls. Additionally, associations with CRC risk were similar for the ratio-based B-vitamin markers and total B-vitamin status (approximately 25% lower risk for high versus low B-vitamin status). In conclusion, ratio-based B-vitamin markers were good predictors of total B-vitamin status and displayed similar associations as total B-vitamin status with CRC risk. Since tHcy and creatinine are routinely clinically analyzed, Hcy:Cre could be easily implemented in clinical practice. This article is protected by copyright. All rights reserved. © 2018 UICC.
Menichetti, Lorenzo; Houot, Sabine; van Oort, Folkert; Kätterer, Thomas; Christensen, Bent T; Chenu, Claire; Barré, Pierre; Vasilyeva, Nadezda A; Ekblad, Alf
2015-03-01
Changes in the (12)C/(13)C ratio (expressed as δ(13)C) of soil organic C (SOC) has been observed over long time scales and with depth in soil profiles. The changes are ascribed to the different reaction kinetics of (12)C and (13)C isotopes and the different isotopic composition of various SOC pool components. However, experimental verification of the subtle isotopic shifts associated with SOC turnover under field conditions is scarce. We determined δ(13)C and SOC in soil sampled during 1929-2009 in the Ap-horizon of five European long-term bare fallow experiments kept without C inputs for 27-80 years and covering a latitudinal range of 11°. The bare fallow soils lost 33-65% of their initial SOC content and showed a mean annual δ(13)C increase of 0.008-0.024‰. The (13)C enrichment could be related empirically to SOC losses by a Rayleigh distillation equation. A more complex mechanistic relationship was also examined. The overall estimate of the fractionation coefficient (ε) was -1.2 ± 0.3‰. This coefficient represents an important input to studies of long-term SOC dynamics in agricultural soils that are based on variations in (13)C natural abundance. The variance of ε may be ascribed to site characteristics not disclosed in our study, but the very similar kinetics measured across our five experimental sites suggest that overall site-specific factors (including climate) had a marginal influence and that it may be possible to isolate a general mechanism causing the enrichment, although pre-fallow land use may have some impact on isotope abundance and fractionation.
Measurement of isotope ratio of Ca{sup +} ions in a linear Paul Trap
DOE Office of Scientific and Technical Information (OSTI.GOV)
Hashimoto, Y.; Minamino, K.; Nagamoto, D.
2009-03-17
Measurement of isotope ratios of Calcium is very useful in many fields. So we demonstrated the measurement of isotope ratios of {sup 40}Ca{sup +}(abundance 96.4%) to {sup 44}Ca{sup +}(2.09%) ions in a linear Paul trap with several laser lights tuning to the isotope shifts. And we found that the experimental parameters had large influences on the measurement of the isotope ratios.
NASA Astrophysics Data System (ADS)
Cescutti, G.; Chiappini, C.
2014-05-01
Context. Thanks to the heroic observational campaigns carried out in recent years we now have large samples of metal-poor stars for which measurements of detailed abundances exist. In particular, large samples of stars with metallicities -5 < [Fe/H] <-1 and measured abundances of Sr, Ba, Y, and Eu are now available. These data hold important clues on the nature of the contribution of the first stellar generations to the enrichment of our Galaxy. Aims: We aim to explain the scatter in Sr, Ba, Y, and Eu abundance ratio diagrams unveiled by the metal-poor halo stars. Methods: We computed inhomogeneous chemical evolution models for the Galactic halo assuming different scenarios for the r-process site: the electron-capture (EC) supernovae and the magnetorotationally driven (MRD) supernovae scenarios. We also considered models with and without the contribution of fast-rotating massive stars (spinstars) to an early enrichment by the s-process. A detailed comparison with the now large sample of stars with measured abundances of Sr, Ba, Y, Eu, and Fe is provided (both in terms of scatter plots and number distributions for several abundance ratios). Results: The scatter observed in these abundance ratios of the very metal-poor stars (with [Fe/H] <-2.5) can be explained by combining the s-process production in spinstars, and the r-process contribution coming from massive stars. For the r-process we have developed models for both the EC and the MRD scenarios that match the observations. Conclusions: With the present observational and theoretical constraints we cannot distinguish between the EC and the MRD scenarios in the Galactic halo. Independently of the r-process scenarios adopted, the production of elements by an s-process in spinstars is needed to reproduce the spread in abundances of the light neutron capture elements (Sr and Y) over heavy neutron capture elements (Ba and Eu). We provide a way to test our suggestions by means of the distribution of the Ba isotopic
Sheng, R; Yan, S M; Qi, L Z; Zhao, Y L
2015-04-01
The objective of this study was to evaluate the effects of the different ratios of unsaturated fatty acids (UFAs) (oleic acid, linoleic acid, and linolenic acid) on the cell viability and triacylglycerol (TAG) content, as well as the mRNA expression of the genes related to lipid and protein synthesis in bovine mammary epithelial cells (BMECs). Primary cells were isolated from the mammary glands of Holstein dairy cows and were passaged twice. Afterward, the cells were randomly allocated to six treatments, five UFA-treated groups, and one control group. For all of the treatments, the the fetal bovine serum in the culture solution was replaced with fatty acid-free BSA (1 g/L), and the cells were treated with different ratios of oleic, linoleic, and linolenic acids (0.75:4:1, 1.5:10:1, 2:13.3:1, 3:20:1, and 4:26.7:1) for 48 h, which were group 1 to group 5. The control culture solution contained only fatty acid-free BSA without UFAs (0 μM). The results indicated that the cell viability was not affected by adding different ratios of UFAs, but the accumulation of TAG was significantly influenced by supplementing with different ratios of UFAs. Adding different ratios of UFAs suppressed the expression of ACACA and FASN but had the opposite effect on the abundances of FABP3 and CD36 mRNA. The expression levels of PPARG, SPEBF1, CSN1S1, and CSN3 mRNA in the BMECs were affected significantly after adding different ratios of UFAs. Our results suggested that groups 1, 2, and 3 (0.75:4:1, 1.5:10:1, and 2:13.3:1) had stronger auxo-action on fat synthesis in the BMECs, where group 3 (2:13.3:1) was the best, followed by group 4 (3:20:1). However, group 5 (4:26.7:1) was the worst. Genes related to protein synthesis in the BMECs were better promoted in groups 2 and 3, and group 3 had the strongest auxo-action, whereas the present study only partly examined the regulation of protein synthesis at the transcriptional level; more studies on translation level are needed in the future
Exploring the CO/CN line ratio in nearby galaxies with the ALMA archive
NASA Astrophysics Data System (ADS)
Wilson, Christine D.
2018-07-01
We describe an archival project using Cycle 0 data from the Atacama Large Millimeter/submillimeter Array to survey the CO/CN line ratio in 17 nearby galaxies. CN is an interesting molecule that traces dense gas exposed to ultraviolet radiation and its N = 1 - 0 lines can be observed simultaneously with the CO J = 1 - 0 line. We identify eight galaxies with distances <200 Mpc for which both lines are detected. Signal-to-noise ratio matched CO/CN ratios range from as low as 7 to as high as 65, while ratios using the total detected flux range from 20 to 140. Spatial variations greater than a factor of 3 are seen in several galaxies. These line ratio changes are likely due to changes in the [CN]/[H2] abundance ratio and/or the CN excitation. Additional measurements of the warm gas pressure and the CN excitation should help to distinguish between these two possibilities. Three of the four active galactic nuclei in our sample show CO/CN line ratios that are roughly a factor of 2-3 larger than those seen in starburst-dominated regions, which may be in conflict with models of molecular abundances in X-ray-dominated regions.
Methven, David A.; Piatt, John F.
1989-01-01
The importance of capelin as prey for cod has long been known (Thompson, 1943; and see Lilly (1987) for a review); however, no studies have been conducted on how the highly dynamic seasonal and yearly variations in capelin abundance affect cod diet. We studied the occurrence of capelin in cod stomachs in relation to the relative abundance of capelin at Witless Bay, Newfoundland (47°15’N 52°46’W), during June, July and August, 1982-1984. The mean number of capelin per stomach and the per cent occurrence of stomachs containing capelin were determined for each collection of stomachs. A total of 680 stomachs were examined. Cod were sampled from those caught in gillnets by fishermen and averaged 66 cm ± 8 (s.d.) in 1983 and 62 cm ± 8 (s.d.) in 1984. Relative abundance of capelin in the local habitat was determined by conducting hydroacoustic surveys around Gull Island in Witless Bay, the same area where cod were collected for stomach content analysis. Only hydroacoustic surveys conducted within three days of cod stomach collections were analyzed. Further details of hydroacoustic surveys including quantifications of acoustic echograms are described in Piatt (1989).
Microsatellite abundance across the Anthozoa and Hydrozoa in the phylum Cnidaria.
Ruiz-Ramos, Dannise V; Baums, Iliana B
2014-10-27
Microsatellite loci have high mutation rates and thus are indicative of mutational processes within the genome. By concentrating on the symbiotic and aposymbiotic cnidarians, we investigated if microsatellite abundances follow a phylogenetic or ecological pattern. Individuals from eight species were shotgun sequenced using 454 GS-FLX Titanium technology. Sequences from the three available cnidarian genomes (Nematostella vectensis, Hydra magnipapillata and Acropora digitifera) were added to the analysis for a total of eleven species representing two classes, three subclasses and eight orders within the phylum Cnidaria. Trinucleotide and tetranucleotide repeats were the most abundant motifs, followed by hexa- and dinucleotides. Pentanucleotides were the least abundant motif in the data set. Hierarchical clustering and log likelihood ratio tests revealed a weak relationship between phylogeny and microsatellite content. Further, comparisons between cnidaria harboring intracellular dinoflagellates and those that do not, show microsatellite coverage is higher in the latter group. Our results support previous studies that found tri- and tetranucleotides to be the most abundant motifs in invertebrates. Differences in microsatellite coverage and composition between symbiotic and non-symbiotic cnidaria suggest the presence/absence of dinoflagellates might place restrictions on the host genome.
Campbell Grant, Evan H.; Jung, Robin E.; Rice, Karen C.
2005-01-01
Stream salamanders are sensitive to acid mine drainage and may be sensitive to acidification and low acid neutralizing capacity (ANC) of a watershed. Streams in Shenandoah National Park, Virginia, are subject to episodic acidification from precipitation events. We surveyed 25 m by 2 m transects located on the stream bank adjacent to the water channel in Shenandoah National Park for salamanders using a stratified random sampling design based on elevation, aspect and bedrock geology. We investigated the relationships of four species (Eurycea bislineata, Desmognathus fuscus, D. monticola and Gyrinophilus porphyriticus) to habitat and water quality variables. We did not find overwhelming evidence that stream salamanders are affected by the acid-base status of streams in Shenandoah National Park. Desmognathus fuscus and D. monticola abundance was greater both in streams that had a higher potential to neutralize acidification, and in higher elevation (>700 m) streams. Neither abundance of E. bislineata nor species richness were related to any of the habitat variables. Our sampling method preferentially detected the adult age class of the study species and did not allow us to estimate population sizes. We suggest that continued monitoring of stream salamander populations in SNP will determine the effects of stream acidification on these taxa.
Sterngren, Anna E.; Rousk, Johannes
2012-01-01
Soil pH is one of the most influential factors for the composition of bacterial and fungal communities, but the influence of soil pH on the distribution and composition of soil archaeal communities has yet to be systematically addressed. The primary aim of this study was to determine how total archaeal abundance (quantitative PCR [qPCR]-based estimates of 16S rRNA gene copy numbers) is related to soil pH across a pH gradient (pH 4.0 to 8.3). Secondarily, we wanted to assess how archaeal abundance related to bacterial and fungal growth rates across the same pH gradient. We identified two distinct and opposite effects of pH on the archaeal abundance. In the lowest pH range (pH 4.0 to 4.7), the abundance of archaea did not seem to correspond to pH. Above this pH range, there was a sharp, almost 4-fold decrease in archaeal abundance, reaching a minimum at pH 5.1 to 5.2. The low abundance of archaeal 16S rRNA gene copy numbers at this pH range then sharply increased almost 150-fold with pH, resulting in an increase in the ratio between archaeal and bacterial copy numbers from a minimum of 0.002 to more than 0.07 at pH 8. The nonuniform archaeal response to pH could reflect variation in the archaeal community composition along the gradient, with some archaea adapted to acidic conditions and others to neutral to slightly alkaline conditions. This suggestion is reinforced by observations of contrasting outcomes of the (competitive) interactions between archaea, bacteria, and fungi toward the lower and higher ends of the examined pH gradient. PMID:22706045
Bengtson, Per; Sterngren, Anna E; Rousk, Johannes
2012-08-01
Soil pH is one of the most influential factors for the composition of bacterial and fungal communities, but the influence of soil pH on the distribution and composition of soil archaeal communities has yet to be systematically addressed. The primary aim of this study was to determine how total archaeal abundance (quantitative PCR [qPCR]-based estimates of 16S rRNA gene copy numbers) is related to soil pH across a pH gradient (pH 4.0 to 8.3). Secondarily, we wanted to assess how archaeal abundance related to bacterial and fungal growth rates across the same pH gradient. We identified two distinct and opposite effects of pH on the archaeal abundance. In the lowest pH range (pH 4.0 to 4.7), the abundance of archaea did not seem to correspond to pH. Above this pH range, there was a sharp, almost 4-fold decrease in archaeal abundance, reaching a minimum at pH 5.1 to 5.2. The low abundance of archaeal 16S rRNA gene copy numbers at this pH range then sharply increased almost 150-fold with pH, resulting in an increase in the ratio between archaeal and bacterial copy numbers from a minimum of 0.002 to more than 0.07 at pH 8. The nonuniform archaeal response to pH could reflect variation in the archaeal community composition along the gradient, with some archaea adapted to acidic conditions and others to neutral to slightly alkaline conditions. This suggestion is reinforced by observations of contrasting outcomes of the (competitive) interactions between archaea, bacteria, and fungi toward the lower and higher ends of the examined pH gradient.
Environmental DNA (eDNA) detects the invasive rusty crayfish Orconectes rusticus at low abundances.
Dougherty, Matthew M; Larson, Eric R; Renshaw, Mark A; Gantz, Crysta A; Egan, Scott P; Erickson, Daniel M; Lodge, David M
2016-06-01
Early detection is invaluable for the cost-effective control and eradication of invasive species, yet many traditional sampling techniques are ineffective at the low population abundances found at the onset of the invasion process. Environmental DNA (eDNA) is a promising and sensitive tool for early detection of some invasive species, but its efficacy has not yet been evaluated for many taxonomic groups and habitat types.We evaluated the ability of eDNA to detect the invasive rusty crayfish Orconectes rusticus and to reflect patterns of its relative abundance, in upper Midwest, USA, inland lakes. We paired conventional baited trapping as a measure of crayfish relative abundance with water samples for eDNA, which were analysed in the laboratory with a qPCR assay. We modelled detection probability for O. rusticus eDNA using relative abundance and site characteristics as covariates and also tested the relationship between eDNA copy number and O. rusticus relative abundance.We detected O. rusticus eDNA in all lakes where this species was collected by trapping, down to low relative abundances, as well as in two lakes where trap catch was zero. Detection probability of O. rusticus eDNA was well predicted by relative abundance of this species and lake water clarity. However, there was poor correspondence between eDNA copy number and O. rusticus relative abundance estimated by trap catches. Synthesis and applications . Our study demonstrates a field and laboratory protocol for eDNA monitoring of crayfish invasions, with results of statistical models that provide guidance of sampling effort and detection probabilities for researchers in other regions and systems. We propose eDNA be included as a tool in surveillance for invasive or imperilled crayfishes and other benthic arthropods.
NASA Astrophysics Data System (ADS)
Bockelée-Morvan, Dominique; Crovisier, J.; Erard, S.; Capaccioni, F.; Leyrat, C.; Filacchione, G.; Drossart, P.; Encrenaz, T.; Biver, N.; de Sanctis, M.-C.; Schmitt, B.; Kührt, E.; Capria, M.-T.; Combes, M.; Combi, M.; Fougere, N.; Arnold, G.; Fink, U.; Ip, W.; Migliorini, A.; Piccioni, G.; Tozzi, G.
2016-11-01
Infrared observations of the coma of 67P/Churyumov-Gerasimenko were carried out from 2015 July to September, I.e. around perihelion (2015 August 13), with the high-resolution channel of the Visible and Infrared Thermal Imaging Spectrometer instrument onboard Rosetta. We present the analysis of fluorescence emission lines of H2O, CO2, 13CO2, OCS, and CH4 detected in limb sounding with the field of view at 2.7-5 km from the comet centre. Measurements are sampling outgassing from the illuminated Southern hemisphere, as revealed by H2O and CO2 raster maps, which show anisotropic distributions, aligned along the projected rotation axis. An abrupt increase of water production is observed 6 d after perihelion. In the meantime, CO2, CH4, and OCS abundances relative to water increased by a factor of 2 to reach mean values of 32, 0.47, and 0.18 per cent, respectively, averaging post-perihelion data. We interpret these changes as resulting from the erosion of volatile-poor surface layers. Sustained dust ablation due to the sublimation of water ice maintained volatile-rich layers near the surface until at least the end of the considered period, as expected for low thermal inertia surface layers. The large abundance measured for CO2 should be representative of the 67P nucleus original composition, and indicates that 67P is a CO2-rich comet. Comparison with abundance ratios measured in the Northern hemisphere shows that seasons play an important role in comet outgassing. The low CO2/H2O values measured above the illuminated Northern hemisphere are not original, but the result of the devolatilization of the uppermost layers.
Gaultier, Alban; Simon, Gabriel; Niessen, Sherry; Dix, Melissa; Takimoto, Shinako; Cravatt, Benjamin F; Gonias, Steven L
2010-12-03
LDL receptor-related protein 1 (LRP1) is an endocytic receptor, reported to regulate the abundance of other receptors in the plasma membrane, including uPAR and tissue factor. The goal of this study was to identify novel plasma membrane proteins, involved in cell-signaling, that are regulated by LRP1. Membrane protein ectodomains were prepared from RAW 264.7 cells in which LRP1 was silenced and control cells using protease K. Peptides were identified by LC-MS/MS. By analysis of spectral counts, 31 transmembrane and secreted proteins were regulated in abundance at least 2-fold when LRP1 was silenced. Validation studies confirmed that semaphorin4D (Sema4D), plexin domain-containing protein-1 (Plxdc1), and neuropilin-1 were more abundant in the membranes of LRP1 gene-silenced cells. Regulation of Plxdc1 by LRP1 was confirmed in CHO cells, as a second model system. Plxdc1 coimmunoprecipitated with LRP1 from extracts of RAW 264.7 cells and mouse liver. Although Sema4D did not coimmunoprecipitate with LRP1, the cell-surface level of Sema4D was increased by RAP, which binds to LRP1 and inhibits binding of other ligands. These studies identify Plxdc1, Sema4D, and neuropilin-1 as novel LRP1-regulated cell-signaling proteins. Overall, LRP1 emerges as a generalized regulator of the plasma membrane proteome.
NASA Astrophysics Data System (ADS)
Moscati, R. J.; Marshall, B. D.
2005-12-01
X-ray microfluorescence (XRMF) spectrometry is a rapid, accurate technique to map element abundances of rock surfaces (such as thin-section billets, the block remaining when a thin section is prepared). Scanning a specimen with a collimated primary X-ray beam (100 μm diameter) generates characteristic secondary X-rays that yield the relative chemical abundances for the major rock-/mineral-forming analytes (such as Si, Al, K, Ca, and Fe). When Cu-rich epoxy is used to impregnate billets, XRMF also can determine porosity from the Cu abundance. Common billet scan size is 30 x 15 mm and the typical mapping time rarely exceeds 2.5 hrs (much faster than traditional point-counting). No polishing or coating is required for the billets, although removing coarse striations or gross irregularities on billet surfaces should improve the spatial accuracy of the maps. Background counts, spectral artifacts, and diffraction peaks typically are inconsequential for maps of major elements. An operational check is performed after every 10 analyses on a standard that contains precisely measured areas of Mn and Mo. Reproducibility of the calculated area ratio of Mn:Mo is consistently within 5% of the known value. For each billet, the single element maps (TIFF files) generated by XRMF are imported into MultiSpec© (a program developed at Purdue University for analysis of multispectral image data, available from http://dynamo.ecn.purdue.edu/~biehl/MultiSpec/) where mineral phases can be spectrally identified and their relative abundances quantified. The element maps for each billet are layered to produce a multi-element file for mineral classification and statistical processing, including modal estimates of mineral abundance. Although mineral identification is possible even if the mineralogy is unknown, prior petrographic examination of the corresponding thin section yields more accurate maps because the software can be set to identify all similar pixels. Caution is needed when using
NASA Astrophysics Data System (ADS)
Shimizu, M. S.; Felix, J. D. D.; Casas, M.; Avery, G. B., Jr.; Kieber, R. J.; Mead, R. N.; Willey, J. D.; Lane, C.
2017-12-01
Ethanol biofuel production and consumption have increased exponentially over the last two decades to help reduce greenhouse gas emissions. Currently, 85% of global ethanol production and consumption occurs in the US and Brazil. Increasing biofuel ethanol usage in these two countries enhances emissions of uncombusted ethanol to the atmosphere contributing to poor air quality. Although measurements of ethanol in the air and the precipitation reveal elevated ethanol concentrations in densely populated cities, other sources such as natural vegetation can contribute to emission to the atmosphere. Previous modeling studies indicated up to 12% of atmospheric ethanol is from anthropogenic emissions. Only one gas phase study in southern Florida attempted to constrain the two sources through direct isotopic measurements. The current study used a stable carbon isotope method to constrain sources of ethanol in rainwater from the US and Brazil. A method was developed using solid phase microextraction (SPME) with subsequent analysis by gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). Stable carbon isotope signatures (δ13C) of vehicle ethanol emission sources for both the US (-9.8‰) and Brazil (-12.7‰) represented C4 plants as feedstock (corn and sugarcane) for biofuel production. An isotope mixing model using biofuel from vehicles (C4 plants) and biogenic (C3 plants) end-members was implemented to estimate ethanol source apportionment in the rain. We found that stable carbon isotope ratio of ethanol in the rain ranged between -22.6‰ and -12.7‰. Our results suggest that the contribution of biofuel to atmospheric ethanol can be higher than previously estimated. As biofuel usage increasing globally, it is essential to determine the relative abundance of anthropogenic ethanol in other areas of the world.
NASA Astrophysics Data System (ADS)
Trujillo-Gomez, Sebastian; Klypin, Anatoly; Primack, Joel; Romanowsky, Aaron J.
2011-11-01
It has long been regarded as difficult if not impossible for a cosmological model to account simultaneously for the galaxy luminosity, mass, and velocity distributions. We revisit this issue using a modern compilation of observational data along with the best available large-scale cosmological simulation of dark matter (DM). We find that the standard cosmological model, used in conjunction with halo abundance matching (HAM) and simple dynamical corrections, fits—at least on average—all basic statistics of galaxies with circular velocities V circ > 80 km s-1 calculated at a radius of ~10 kpc. Our primary observational constraint is the luminosity-velocity (LV) relation—which generalizes the Tully-Fisher and Faber-Jackson relations in allowing all types of galaxies to be included, and provides a fundamental benchmark to be reproduced by any theory of galaxy formation. We have compiled data for a variety of galaxies ranging from dwarf irregulars to giant ellipticals. The data present a clear monotonic LV relation from ~50 km s-1 to ~500 km s-1, with a bend below ~80 km s-1 and a systematic offset between late- and early-type galaxies. For comparison to theory, we employ our new ΛCDM "Bolshoi" simulation of DM, which has unprecedented mass and force resolution over a large cosmological volume, while using an up-to-date set of cosmological parameters. We use HAM to assign rank-ordered galaxy luminosities to the DM halos, a procedure that automatically fits the empirical luminosity function and provides a predicted LV relation that can be checked against observations. The adiabatic contraction of DM halos in response to the infall of the baryons is included as an optional model ingredient. The resulting predictions for the LV relation are in excellent agreement with the available data on both early-type and late-type galaxies for the luminosity range from Mr = -14 to Mr = -22. We also compare our predictions for the "cold" baryon mass (i.e., stars and cold gas) of
NASA Astrophysics Data System (ADS)
Yu, Jing; Cheng, Siwei; Xu, Bin
Recently there are many literatures studying the effect of factors such as size or book-market ratio on fluctuation of accounting earnings, stock price or earnings respectively, but so far their affection on accounting information value relativity has been scarcely addressed. This paper presents the detail analyses of their effect of the two factors to the relativity of accounting information value respectively by taking Shanghai and Shenzhen stock markets as sample. And the analyses supports the following two hypotheses, (1) The relativity of accounting information value of big size corporation is more than that of small size corporation. (2) The relativity of accounting information value of low B/M ratio corporation is more than that of low B/M ratio corporation.
Matlack, R.S.; Gipson, P.S.; Kaufman, D.W.
2000-01-01
We assessed suitability of cropland and shortgrass rangeland for swift foxes (Vulpes velox) in western Kansas. Relative abundance and survival were similar for foxes in rangeland and cropland. Mortality resulting from non-traumatic causes, coyotes, and motor vehicles differed significantly between habitats. Predation by coyotes, motor vehicles, and non-traumatic causes were responsible for 45%, 36%, and 18%, respectively, of 11 deaths in rangeland and 20%, 10%, and 70%, respectively, of 10 deaths in cropland. Swift foxes in rangeland were larger and in better condition than those in cropland. Males were larger than females based on mass, standardized mass (mass/body length), body length, hindfoot length, and ear length.
Manganese Abundances in the Stars with Metallicities -1 <[Fe/H]< +0.3
NASA Astrophysics Data System (ADS)
Mishenina, T.; Gorbaneva, T.; Pignatari, M.; Thielemann, F.-K.; Korotin, S.
2018-01-01
We estimate the Mn abundances in the atmospheres of 247 F-G-K-type dwarf stars belonging to the thin and thick disk populations in the metallicity range -1 < [Fe/H] < +0.3. The observations were conducted using the 1.93 m telescope at Observatoire de Haute-Provence (OHP, France) equipped with the echelle type spectrographs ELODIE and SOPHIE. The abundances were derived under the LTE approximation; the synthetic spectrum for the Mn lines was computed accounting for the hyperfine structure. Starting from the results obtained, we discuss the evolution of the [Mn/Fe] ratio with respect to [Fe/H] in the galactic disk.
NASA Technical Reports Server (NTRS)
Irvine, W. M.; Dickens, J. E.; Lovell, A. J.; Schloerb, F. P.; Senay, M.; Bergin, E. A.; Jewitt, D.; Matthews, H. E.; Ferris, J. P. (Principal Investigator)
1997-01-01
The abundance ratio of the isomers HCN and HNC has been investigated in comet Hale-Bopp (C/1995 O1) through observations of the J = 4-3 rotational transitions of both species for heliocentric distances 0.93 < r < 3 AU, both pre- and post-perihelion. After correcting for the optical depth of the stronger HCN line, we find that the column density ratio of HNC/HCN in our telescope beam increases significantly as the comet approaches the Sun. We compare this behavior to that predicted from an ion-molecule chemical model and conclude that the HNC is produced in significant measure by chemical processes in the coma; i.e., for comet Hale-Bopp, HNC is not a parent molecule sublimating from the nucleus.
Can Occupancy–Abundance Models Be Used to Monitor Wolf Abundance?
Latham, M. Cecilia; Latham, A. David M.; Webb, Nathan F.; Mccutchen, Nicole A.; Boutin, Stan
2014-01-01
Estimating the abundance of wild carnivores is of foremost importance for conservation and management. However, given their elusive habits, direct observations of these animals are difficult to obtain, so abundance is more commonly estimated from sign surveys or radio-marked individuals. These methods can be costly and difficult, particularly in large areas with heavy forest cover. As an alternative, recent research has suggested that wolf abundance can be estimated from occupancy–abundance curves derived from “virtual” surveys of simulated wolf track networks. Although potentially more cost-effective, the utility of this approach hinges on its robustness to violations of its assumptions. We assessed the sensitivity of the occupancy–abundance approach to four assumptions: variation in wolf movement rates, changes in pack cohesion, presence of lone wolves, and size of survey units. Our simulations showed that occupancy rates and wolf pack abundances were biased high if track surveys were conducted when wolves made long compared to short movements, wolf packs were moving as multiple hunting units as opposed to a cohesive pack, and lone wolves were moving throughout the surveyed landscape. We also found that larger survey units (400 and 576 km2) were more robust to changes in these factors than smaller survey units (36 and 144 km2). However, occupancy rates derived from large survey units rapidly reached an asymptote at 100% occupancy, suggesting that these large units are inappropriate for areas with moderate to high wolf densities (>15 wolves/1,000 km2). Virtually-derived occupancy–abundance relationships can be a useful method for monitoring wolves and other elusive wildlife if applied within certain constraints, in particular biological knowledge of the surveyed species needs to be incorporated into the design of the occupancy surveys. Further, we suggest that the applicability of this method could be extended by directly incorporating some of its
WASP (Write a Scientific Paper) using Excel - 12: Odds ratio and relative risk.
Grech, Victor
2018-07-01
The calculation of odds ratios and relative risks may be required as part of a data analysis exercise. This paper explains how to set up these calculations in Microsoft Excel from a two by two contingency table. Copyright © 2018 Elsevier B.V. All rights reserved.
Measuring molecular abundances in comet C/2014 Q2 (Lovejoy) using the APEX telescope
NASA Astrophysics Data System (ADS)
de Val-Borro, M.; Milam, S. N.; Cordiner, M. A.; Charnley, S. B.; Coulson, I. M.; Remijan, A. J.; Villanueva, G. L.
2018-02-01
Comet composition provides critical information on the chemical and physical processes that took place during the formation of the Solar system. We report here on millimetre spectroscopic observations of the long-period bright comet C/2014 Q2 (Lovejoy) using the Atacama Pathfinder Experiment (APEX) band 1 receiver between 2015 January UT 16.948 and 18.120, when the comet was at heliocentric distance of 1.30 au and geocentric distance of 0.53 au. Bright comets allow for sensitive observations of gaseous volatiles that sublimate in their coma. These observations allowed us to detect HCN, CH3OH (multiple transitions), H2CO and CO, and to measure precise molecular production rates. Additionally, sensitive upper limits were derived on the complex molecules acetaldehyde (CH3CHO) and formamide (NH2CHO) based on the average of the strongest lines in the targeted spectral range to improve the signal-to-noise ratio. Gas production rates are derived using a non-LTE molecular excitation calculation involving collisions with H2O and radiative pumping that becomes important in the outer coma due to solar radiation. We find a depletion of CO in C/2014 Q2 (Lovejoy) with a production rate relative to water of 2.0 per cent, and relatively low abundances of Q(HCN)/Q(H2O), 0.1 per cent, and Q(H2CO)/Q(H2O), 0.2 per cent. In contrast, the CH3OH relative abundance Q(CH3OH)/Q(H2O), 2.2 per cent, is close to the mean value observed in other comets. The measured production rates are consistent with values derived for this object from other facilities at similar wavelengths taking into account the difference in the fields of view. Based on the observed mixing ratios of organic molecules in four bright comets including C/2014 Q2, we find some support for atom addition reactions on cold dust being the origin of some of the molecules.
Multi-scale models of grassland passerine abundance in a fragmented system in Wisconsin
Renfrew, R.B.; Ribic, C.A.
2008-01-01
Fragmentation of grasslands has been implicated in grassland bird population declines. Multi-scale models are being increasingly used to assess potential factors that influence grassland bird presence, abundance, and productivity. However, studies rarely assess fragmentation metrics, and seldom evaluate more than two scales or interactions among scales. We evaluated the relative importance of characteristics at multiple scales to patterns in relative abundance of Savannah Sparrow (Passerculus sandwichensis), Grasshopper Sparrow (Ammodramus savannarum), Eastern Meadowlark (Sturnella magna), and Bobolink (Dolichonyx oryzivorus). We surveyed birds in 74 southwestern Wisconsin pastures from 1997 to 1999 and compared models with explanatory variables from multiple scales: within-patch vegetation structure (microhabitat), patch (macrohabitat), and three landscape extents. We also examined interactions between macrohabitat and landscape factors. Core area of pastures was an important predictor of relative abundance, and composition of the landscape was more important than configuration. Relative abundance was frequently higher in pastures with more core area and in landscapes with more grassland and less wooded area. The direction and strength of the effect of core pasture size on relative abundance changed depending on amount of wooded area in the landscape. Relative abundance of grassland birds was associated with landscape variables more frequently at the 1200-m scale than at smaller scales. To develop better predictive models, parameters at multiple scales and their interactive effects should be included, and results should be evaluated in the context of microhabitat variability, landscape composition, and fragmentation in the study area. ?? 2007 Springer Science+Business Media B.V.
Natural abundant (17) O NMR in a 1.5-T Halbach magnet.
Sørensen, Morten K; Bakharev, Oleg N; Jensen, Ole; Nielsen, Niels Chr
2016-06-01
We present mobile, low-field (17) O NMR as a means for monitoring oxygen in liquids. Whereas oxygen is one of the most important elements, oxygen NMR is limited by a poor sensitivity related to low natural abundance and gyro-magnetic ratio of the NMR active (17) O isotope. Here, we demonstrate (17) O NMR detection at a Larmor frequency of 8.74 MHz in a 1.5-T Halbach neodymium magnet with a home-built digital NMR instrument suitable for large-scale production and in-line monitoring applications. The proposed (17) O NMR sensor may be applied for direct, noninvasive measurements of water content in, for example, oil, manure, or food in automated quality or process control. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.
Litzow, Michael A.; Piatt, John F.; Abookire, Alisa A.; Robards, Martin D.
2004-01-01
1. The quality-variability trade-off hypothesis predicts that (i) energy density (kJ g-1) and spatial-temporal variability in abundance are positively correlated in nearshore marine fishes; and (ii) prey selection by a nearshore piscivore, the pigeon guillemot (Cepphus columba Pallas), is negatively affected by variability in abundance. 2. We tested these predictions with data from a 4-year study that measured fish abundance with beach seines and pigeon guillemot prey utilization with visual identification of chick meals. 3. The first prediction was supported. Pearson's correlation showed that fishes with higher energy density were more variable on seasonal (r = 0.71) and annual (r = 0.66) time scales. Higher energy density fishes were also more abundant overall (r = 0.85) and more patchy at a scale of 10s of km (r = 0.77). 4. Prey utilization by pigeon guillemots was strongly non-random. Relative preference, defined as the difference between log-ratio transformed proportions of individual prey taxa in chick diets and beach seine catches, was significantly different from zero for seven of the eight main prey categories. 5. The second prediction was also supported. We used principal component analysis (PCA) to summarize variability in correlated prey characteristics (energy density, availability and variability in abundance). Two PCA scores explained 32% of observed variability in pigeon guillemot prey utilization. Seasonal variability in abundance was negatively weighted by these PCA scores, providing evidence of risk-averse selection. Prey availability, energy density and km-scale variability in abundance were positively weighted. 6. Trophic interactions are known to create variability in resource distribution in other systems. We propose that links between resource quality and the strength of trophic interactions may produce resource quality-variability trade-offs.
NASA Astrophysics Data System (ADS)
Vennes, S.; Kawka, A.; Németh, P.
2011-06-01
We present a detailed model atmosphere analysis of high-dispersion and high signal-to-noise ratio spectra of the heavily polluted DAZ white dwarf GALEX J1931+0117. The spectra obtained with the Very Large Telescope (VLT)-Kueyen/UV-Visual Echelle Spectrograph show several well-resolved Si II spectral lines enabling a study of pressure effects on line profiles. We observed large Stark shifts in silicon lines in agreement with theoretical predictions and laboratory measurements. Taking into account Stark shifts in the calculation of synthetic spectra, we reduced the scatter in individual line radial velocity measurements from ˜3 to ≲1 km s-1. We present revised abundances of O, Mg, Si, Ca and Fe based on a critical review of line-broadening parameters and oscillator strengths. The new measurements are generally in agreement with our previous analysis with the exception of magnesium with a revised abundance of a factor of 2 lower than previously estimated. The magnesium, silicon and iron abundances exceed solar abundances, but the oxygen and calcium abundances are below solar. Also, we compared the observed line profiles to synthetic spectra computed with variable accretion rates and vertical abundance distributions assuming diffusive steady state. The inferred accretion rates vary from ? for calcium to 2 × 109 g s-1 for oxygen. We find that the accretion flow must be oxygen rich while being deficient in calcium relative to solar abundances. The lack of radial velocity variations between two measurement epochs suggests that GALEX J1931+0117 is probably not in a close binary and that the source of the accreted material resides in a debris disc. Based on observations made with European Southern Observatory (ESO) telescopes at the La Silla Paranal Observatory under programme 283.D-5060.
Implications of Abundant Gas and Oil for Climate Forcing
NASA Astrophysics Data System (ADS)
Edmonds, J.
2015-12-01
Perhaps the most important development in the field of energy over the past decade has been the advent of technologies that enable the production of larger volumes of natural gas and oil at lower cost. The availability of more abundant gas and oil is reshaping the global energy system, with implications for both evolving emissions of CO2 and other climate forcers. More abundant gas and oil will also transform the character of greenhouse gas emissions mitigation. We review recent findings regarding the impact of abundant gas and oil for climate forcing and the challenge of emissions mitigation. We find strong evidence that, absent policies to limits its penetration against renewable energy, abundant gas has little observable impact on CO2 emissions, and tends to increase overall climate forcing, though the latter finding is subject to substantial uncertainty. The presence of abundant gas also affects emissions mitigation. There is relatively little literature exploring the implication of expanded gas availability on the difficulty in meeting emissions mitigation goals. However, preliminary results indicate that on global scales abundant gas does not substantially affect the cost of emissions mitigation, even though natural gas could have an expanded role in emissions mitigation scenarios as compared with scenarios in which natural gas is less abundant.
Disk Evolution, Element Abundances and Cloud Properties of Young Gas Giant Planets
Helling, Christiane; Woitke, Peter; Rimmer, Paul B.; Kamp, Inga; Thi, Wing-Fai; Meijerink, Rowin
2014-01-01
We discuss the chemical pre-conditions for planet formation, in terms of gas and ice abundances in a protoplanetary disk, as function of time and position, and the resulting chemical composition and cloud properties in the atmosphere when young gas giant planets form, in particular discussing the effects of unusual, non-solar carbon and oxygen abundances. Large deviations between the abundances of the host star and its gas giants seem likely to occur if the planet formation follows the core-accretion scenario. These deviations stem from the separate evolution of gas and dust in the disk, where the dust forms the planet cores, followed by the final run-away accretion of the left-over gas. This gas will contain only traces of elements like C, N and O, because those elements have frozen out as ices. ProDiMo protoplanetary disk models are used to predict the chemical evolution of gas and ice in the midplane. We find that cosmic rays play a crucial role in slowly un-blocking the CO, where the liberated oxygen forms water, which then freezes out quickly. Therefore, the C/O ratio in the gas phase is found to gradually increase with time, in a region bracketed by the water and CO ice-lines. In this regions, C/O is found to approach unity after about 5 Myrs, scaling with the cosmic ray ionization rate assumed. We then explore how the atmospheric chemistry and cloud properties in young gas giants are affected when the non-solar C/O ratios predicted by the disk models are assumed. The Drift cloud formation model is applied to study the formation of atmospheric clouds under the influence of varying premordial element abundances and its feedback onto the local gas. We demonstrate that element depletion by cloud formation plays a crucial role in converting an oxygen-rich atmosphere gas into carbon-rich gas when non-solar, premordial element abundances are considered as suggested by disk models. PMID:25370190
Disk evolution, element abundances and cloud properties of young gas giant planets.
Helling, Christiane; Woitke, Peter; Rimmer, Paul B; Kamp, Inga; Thi, Wing-Fai; Meijerink, Rowin
2014-04-14
We discuss the chemical pre-conditions for planet formation, in terms of gas and ice abundances in a protoplanetary disk, as function of time and position, and the resulting chemical composition and cloud properties in the atmosphere when young gas giant planets form, in particular discussing the effects of unusual, non-solar carbon and oxygen abundances. Large deviations between the abundances of the host star and its gas giants seem likely to occur if the planet formation follows the core-accretion scenario. These deviations stem from the separate evolution of gas and dust in the disk, where the dust forms the planet cores, followed by the final run-away accretion of the left-over gas. This gas will contain only traces of elements like C, N and O, because those elements have frozen out as ices. PRODIMO protoplanetary disk models are used to predict the chemical evolution of gas and ice in the midplane. We find that cosmic rays play a crucial role in slowly un-blocking the CO, where the liberated oxygen forms water, which then freezes out quickly. Therefore, the C/O ratio in the gas phase is found to gradually increase with time, in a region bracketed by the water and CO ice-lines. In this regions, C/O is found to approach unity after about 5 Myrs, scaling with the cosmic ray ionization rate assumed. We then explore how the atmospheric chemistry and cloud properties in young gas giants are affected when the non-solar C/O ratios predicted by the disk models are assumed. The DRIFT cloud formation model is applied to study the formation of atmospheric clouds under the influence of varying premordial element abundances and its feedback onto the local gas. We demonstrate that element depletion by cloud formation plays a crucial role in converting an oxygen-rich atmosphere gas into carbon-rich gas when non-solar, premordial element abundances are considered as suggested by disk models.
Direct uranium isotope ratio analysis of single micrometer-sized glass particles
Kappel, Stefanie; Boulyga, Sergei F.; Prohaska, Thomas
2012-01-01
We present the application of nanosecond laser ablation (LA) coupled to a ‘Nu Plasma HR’ multi collector inductively coupled plasma mass spectrometer (MC-ICP-MS) for the direct analysis of U isotope ratios in single, 10–20 μm-sized, U-doped glass particles. Method development included studies with respect to (1) external correction of the measured U isotope ratios in glass particles, (2) the applied laser ablation carrier gas (i.e. Ar versus He) and (3) the accurate determination of lower abundant 236U/238U isotope ratios (i.e. 10−5). In addition, a data processing procedure was developed for evaluation of transient signals, which is of potential use for routine application of the developed method. We demonstrate that the developed method is reliable and well suited for determining U isotope ratios of individual particles. Analyses of twenty-eight S1 glass particles, measured under optimized conditions, yielded average biases of less than 0.6% from the certified values for 234U/238U and 235U/238U ratios. Experimental results obtained for 236U/238U isotope ratios deviated by less than −2.5% from the certified values. Expanded relative total combined standard uncertainties Uc (k = 2) of 2.6%, 1.4% and 5.8% were calculated for 234U/238U, 235U/238U and 236U/238U, respectively. PMID:22595724
Direct uranium isotope ratio analysis of single micrometer-sized glass particles.
Kappel, Stefanie; Boulyga, Sergei F; Prohaska, Thomas
2012-11-01
We present the application of nanosecond laser ablation (LA) coupled to a 'Nu Plasma HR' multi collector inductively coupled plasma mass spectrometer (MC-ICP-MS) for the direct analysis of U isotope ratios in single, 10-20 μm-sized, U-doped glass particles. Method development included studies with respect to (1) external correction of the measured U isotope ratios in glass particles, (2) the applied laser ablation carrier gas (i.e. Ar versus He) and (3) the accurate determination of lower abundant (236)U/(238)U isotope ratios (i.e. 10(-5)). In addition, a data processing procedure was developed for evaluation of transient signals, which is of potential use for routine application of the developed method. We demonstrate that the developed method is reliable and well suited for determining U isotope ratios of individual particles. Analyses of twenty-eight S1 glass particles, measured under optimized conditions, yielded average biases of less than 0.6% from the certified values for (234)U/(238)U and (235)U/(238)U ratios. Experimental results obtained for (236)U/(238)U isotope ratios deviated by less than -2.5% from the certified values. Expanded relative total combined standard uncertainties U(c) (k = 2) of 2.6%, 1.4% and 5.8% were calculated for (234)U/(238)U, (235)U/(238)U and (236)U/(238)U, respectively. Copyright © 2012 Elsevier Ltd. All rights reserved.
NASA Astrophysics Data System (ADS)
Marshall, B. D.; Moscati, R. J.
2005-12-01
Yucca Mountain, a ridge of shallowly dipping, Miocene-age volcanic rocks in southwest Nevada, is the proposed site for a nuclear waste repository to be constructed in the 500- to 700-m-thick unsaturated zone (UZ). At the proposed repository, the 300-m-thick Topopah Spring Tuff welded unit (TSw) is overlain by approximately 30 m of nonwelded tuffs (PTn); the Tiva Canyon Tuff welded unit (TCw) overlies the PTn with a range in thickness from 0 to approximately 130 m at the site. The amount of water percolation through the UZ is low and difficult to measure directly, but local seepage into mined tunnels has been observed in the TCw. Past water seepage in the welded tuffs is recorded by widespread, thin (0.3 cm) coatings of calcite and silica on fracture surfaces and within cavities. Abundances of calcite and silica in the coatings were determined by X-ray microfluorescence mapping and subsequent multispectral image analysis of over 200 samples. The images were classified into constituent phases including opal-chalcedony-quartz (secondary silica) and calcite. In the TCw samples, the median calcite/silica ratio is 8; in the TSw samples within 35 m below the PTn, median calcite/silica falls to 2, perhaps reflecting an increase in soluble silica from the presence of glass in the nonwelded tuffs. In the deeper parts of the TSw, median calcite/silica reaches 100 and many samples contain no detectable secondary silica phase. Evaporation and changing pCO2 control precipitation of calcite from water percolating downward in the UZ, but precipitation of opal requires only evaporation. Calcite/silica ratios, therefore, can constrain the relative importance of evaporation in the UZ. Although calcite/silica values scatter widely within the TSw, reflecting the spatial variability of gas and water flow, average calcite/silica ratios increase with stratigraphic depth, indicating less evaporation at the deeper levels of the UZ. Coupled with the much smaller calcite/silica ratios
DOE Office of Scientific and Technical Information (OSTI.GOV)
Beck, Markus H.; Inman, Ross B.; Strand, Michael R.
2007-03-01
Polydnaviruses (PDVs) are distinguished by their unique association with parasitoid wasps and their segmented, double-stranded (ds) DNA genomes that are non-equimolar in abundance. Relatively little is actually known, however, about genome packaging or segment abundance of these viruses. Here, we conducted electron microscopy (EM) and real-time polymerase chain reaction (PCR) studies to characterize packaging and segment abundance of Microplitis demolitor bracovirus (MdBV). Like other PDVs, MdBV replicates in the ovaries of females where virions accumulate to form a suspension called calyx fluid. Wasps then inject a quantity of calyx fluid when ovipositing into hosts. The MdBV genome consists of 15more » segments that range from 3.6 (segment A) to 34.3 kb (segment O). EM analysis indicated that MdBV virions contain a single nucleocapsid that encapsidates one circular DNA of variable size. We developed a semi-quantitative real-time PCR assay using SYBR Green I. This assay indicated that five (J, O, H, N and B) segments of the MdBV genome accounted for more than 60% of the viral DNAs in calyx fluid. Estimates of relative segment abundance using our real-time PCR assay were also very similar to DNA size distributions determined from micrographs. Analysis of parasitized Pseudoplusia includens larvae indicated that copy number of MdBV segments C, B and J varied between hosts but their relative abundance within a host was virtually identical to their abundance in calyx fluid. Among-tissue assays indicated that each viral segment was most abundant in hemocytes and least abundant in salivary glands. However, the relative abundance of each segment to one another was similar in all tissues. We also found no clear relationship between MdBV segment and transcript abundance in hemocytes and fat body.« less
NASA Astrophysics Data System (ADS)
Mashonkina, Lyudmila; Jablonka, Pascale; Sitnova, Tatyana; Pakhomov, Yuri; North, Pierre
2018-06-01
We review recent abundance results for very metal-poor (VMP, -4 ≤ [Fe/H] ≤ -2) stars in seven dwarf spheroidal galaxies (dSphs) and in the Milky Way (MW) halo comparison sample that were obtained based on high-resolution spectroscopic datasets, homogeneous and accurate atmospheric parameters, and the non-local thermodynamic equilibrium (NLTE) line formation for 10 chemical species. A remarkable gain of using such an approach is the reduction, compared to a simple compilation of the literature data, of the spread in abundance ratios at given metallicity within each galaxy and from one to the other. We show that all massive galaxies in our sample, that is, the MW halo and the classical dSphs Sculptor, Ursa Minor, Sextans, and Fornax, reveal a similar plateau at [α/Fe] \\simeq 0.3 for each of the α-process elements: Mg, Ca, and Ti. We put on a firm ground the evidence for a decline in α/Fe with increasing metallicity in the Boötes I ultra-faint dwarf galaxy (UFD), that is most probably due to the ejecta of type Ia supernovae. In our classical dSphs, we observe the dichotomy in the [Sr/Ba] versus [Ba/H] diagram, similarly to the MW halo, calling for two different nucleosynthesis channels for Sr at the earliest evolution stages of these galaxies. Our three UFDs, that is Boötes I, UMa II, and Leo IV, are depleted in Sr and Ba relative to Fe and Mg, with very similar ratios of [Sr/Mg] ≈ -1.3 and [Ba/Mg] ≈ -1 on the entire range of their Mg abundances. The subsolar Sr/Ba ratios of Boötes I and UMa II indicate a common r-process origin of their neutron-capture elements. For Na/Fe, Na/Mg, and Al/Mg, the MW halo and all dSphs reveal indistinguishable trends with metallicity, suggesting that the processes of Na and Al synthesis are identical in all systems, independent of their mass. Sculptor remains the classical dSph, in which the evidence for inhomogeneous mixing in the early evolution stage, at [Fe/H] < -2, is the strongest.
Precise and accurate isotope ratio measurements by ICP-MS.
Becker, J S; Dietze, H J
2000-09-01
The precise and accurate determination of isotope ratios by inductively coupled plasma mass spectrometry (ICP-MS) and laser ablation ICP-MS (LA-ICP-MS) is important for quite different application fields (e.g. for isotope ratio measurements of stable isotopes in nature, especially for the investigation of isotope variation in nature or age dating, for determining isotope ratios of radiogenic elements in the nuclear industry, quality assurance of fuel material, for reprocessing plants, nuclear material accounting and radioactive waste control, for tracer experiments using stable isotopes or long-lived radionuclides in biological or medical studies). Thermal ionization mass spectrometry (TIMS), which used to be the dominant analytical technique for precise isotope ratio measurements, is being increasingly replaced for isotope ratio measurements by ICP-MS due to its excellent sensitivity, precision and good accuracy. Instrumental progress in ICP-MS was achieved by the introduction of the collision cell interface in order to dissociate many disturbing argon-based molecular ions, thermalize the ions and neutralize the disturbing argon ions of plasma gas (Ar+). The application of the collision cell in ICP-QMS results in a higher ion transmission, improved sensitivity and better precision of isotope ratio measurements compared to quadrupole ICP-MS without the collision cell [e.g., for 235U/238U approximately 1 (10 microg x L(-1) uranium) 0.07% relative standard deviation (RSD) vs. 0.2% RSD in short-term measurements (n = 5)]. A significant instrumental improvement for ICP-MS is the multicollector device (MC-ICP-MS) in order to obtain a better precision of isotope ratio measurements (with a precision of up to 0.002%, RSD). CE- and HPLC-ICP-MS are used for the separation of isobaric interferences of long-lived radionuclides and stable isotopes by determination of spallation nuclide abundances in an irradiated tantalum target.
TRACING THE EVOLUTION OF HIGH-REDSHIFT GALAXIES USING STELLAR ABUNDANCES
DOE Office of Scientific and Technical Information (OSTI.GOV)
Crosby, Brian D.; O’Shea, Brian W.; Beers, Timothy C.
2016-03-20
This paper presents the first results from a model for chemical evolution that can be applied to N-body cosmological simulations and quantitatively compared to measured stellar abundances from large astronomical surveys. This model convolves the chemical yield sets from a range of stellar nucleosynthesis calculations (including asymptotic giant branch stars, Type Ia and II supernovae, and stellar wind models) with a user-specified stellar initial mass function (IMF) and metallicity to calculate the time-dependent chemical evolution model for a “simple stellar population” (SSP) of uniform metallicity and formation time. These SSP models are combined with a semianalytic model for galaxy formation andmore » evolution that uses merger trees from N-body cosmological simulations to track several α- and iron-peak elements for the stellar and multiphase interstellar medium components of several thousand galaxies in the early (z ≥ 6) universe. The simulated galaxy population is then quantitatively compared to two complementary data sets of abundances in the Milky Way stellar halo and is capable of reproducing many of the observed abundance trends. The observed abundance ratio distributions are best reproduced with a Chabrier IMF, a chemically enriched star formation efficiency of 0.2, and a redshift of reionization of 7. Many abundances are qualitatively well matched by our model, but our model consistently overpredicts the carbon-enhanced fraction of stars at low metallicities, likely owing to incomplete coverage of Population III stellar yields and supernova models and the lack of dust as a component of our model.« less
Ito, Tadashi; Sakai, Yoshihito; Nakamura, Eishi; Yamazaki, Kazunori; Yamada, Ayaka; Sato, Noritaka; Morita, Yoshifumi
2015-07-01
[Purpose] The purpose of this study was to examine the relationship between the paraspinal muscle cross-sectional area and the relative proprioceptive weighting ratio during local vibratory stimulation of older persons with lumbar spondylosis in an upright position. [Subjects] In all, 74 older persons hospitalized for lumbar spondylosis were included. [Methods] We measured the relative proprioceptive weighting ratio of postural sway using a Wii board while vibratory stimulations of 30, 60, or 240 Hz were applied to the subjects' paraspinal or gastrocnemius muscles. Back strength, abdominal muscle strength, and erector spinae muscle (L1/L2, L4/L5) and lumbar multifidus (L1/L2, L4/L5) cross-sectional areas were evaluated. [Results] The erector spinae muscle (L1/L2) cross-sectional area was associated with the relative proprioceptive weighting ratio during 60Hz stimulation. [Conclusion] These findings show that the relative proprioceptive weighting ratio compared to the erector spinae muscle (L1/L2) cross-sectional area under 60Hz proprioceptive stimulation might be a good indicator of trunk proprioceptive sensitivity.
IASI-derived NH3 enhancement ratios relative to CO for the tropical biomass burning regions
NASA Astrophysics Data System (ADS)
Whitburn, Simon; Van Damme, Martin; Clarisse, Lieven; Hurtmans, Daniel; Clerbaux, Cathy; Coheur, Pierre-François
2017-10-01
Vegetation fires are a major source of ammonia (NH3) in the atmosphere. Their emissions are mainly estimated using bottom-up approaches that rely on uncertain emission factors. In this study, we derive new biome-specific NH3 enhancement ratios relative to carbon monoxide (CO), ERNH3 / CO (directly related to the emission factors), from the measurements of the IASI sounder onboard the Metop-A satellite. This is achieved for large tropical regions and for an 8-year period (2008-2015). We find substantial differences in the ERNH3 / CO ratios between the biomes studied, with calculated values ranging from 7 × 10-3 to 23 × 10-3. For evergreen broadleaf forest these are typically 50-75 % higher than for woody savanna and savanna biomes. This variability is attributed to differences in fuel types and size and is in line with previous studies. The analysis of the spatial and temporal distribution of the ERNH3 / CO ratio also reveals a (sometimes large) within-biome variability. On a regional level, woody savanna shows, for example, a mean ERNH3 / CO ratio for the region of Africa south of the Equator that is 40-75 % lower than in the other five regions studied, probably reflecting regional differences in fuel type and burning conditions. The same variability is also observed on a yearly basis, with a peak in the ERNH3 / CO ratio observed for the year 2010 for all biomes. These results highlight the need for the development of dynamic emission factors that take into better account local variations in fuel type and fire conditions. We also compare the IASI-derived ERNH3 / CO ratio with values reported in the literature, usually calculated from ground-based or airborne measurements. We find general good agreement in the referenced ERNH3 / CO ratio except for cropland, for which the ERNH3 / CO ratio shows an underestimation of about 2-2.5 times.
NASA Astrophysics Data System (ADS)
Shi, Wei-Bin; Liang, Yan-Chun; Shao, Xu; Liu, Xiao-Wei; Zhao, Gang; Hammer, Francois; Zhang, Yong; Flores, Hector; Ruan, Gui-Ping; Zhou, Li
2014-07-01
We select 947 star-forming galaxies from SDSS-DR7 with [O III]λ4363 emission lines detected at a signal-to-noise ratio larger than 5σ. Their electron temperatures and direct oxygen abundances are then determined. We compare the results from different methods. t2, the electron temperature in the low ionization region, estimated from t3, that in the high ionization region, is compared using three analysis relations between t2 - t3. These show obvious differences, which result in some different ionic oxygen abundances. The results of t3, t2, O++/H+ and O+/H+ derived by using methods from IRAF and literature are also compared. The ionic abundances O++/H+ are higher than O+/H+ for most cases. The different oxygen abundances derived from Te and the strong-line ratios show a clear discrepancy, which is more obvious following increasing stellar mass and strong-line ratio R23. The sample of galaxies from SDSS with detected [O III]λ4363 have lower metallicites and higher star formation rates, so they may not be typical representatives of the whole population of galaxies. Adopting data objects from Andrews & Martini, Liang et al. and Lee et al. data, we derive new relations of stellar mass and metallicity for star-forming galaxies in a much wider stellar mass range: from 106 Msolar to 1011 Msolar.
AGB Sodium Abundances in the Globular Cluster 47 Tucanae (NGC 104)
NASA Astrophysics Data System (ADS)
Johnson, Christian I.; McDonald, Iain; Pilachowski, Catherine A.; Mateo, Mario; Bailey, John I., III; Cordero, Maria J.; Zijlstra, Albert A.; Crane, Jeffrey D.; Olszewski, Edward; Shectman, Stephen A.; Thompson, Ian
2015-02-01
A recent analysis comparing the [Na/Fe] distributions of red giant branch (RGB) and asymptotic giant branch (AGB) stars in the Galactic globular cluster NGC 6752 found that the ratio of Na-poor to Na-rich stars changes from 30:70 on the RGB to 100:0 on the AGB. The surprising paucity of Na-rich stars on the AGB in NGC 6752 warrants additional investigations to determine if the failure of a significant fraction of stars to ascend the AGB is an attribute common to all globular clusters. Therefore, we present radial velocities, [Fe/H], and [Na/Fe] abundances for 35 AGB stars in the Galactic globular cluster 47 Tucanae (47 Tuc; NGC 104), and compare the AGB [Na/Fe] distribution with a similar RGB sample published previously. The abundances and velocities were derived from high-resolution spectra obtained with the Michigan/Magellan Fiber System and MSpec spectrograph on the Magellan-Clay 6.5 m telescope. We find the average heliocentric radial velocity and [Fe/H] values to be < R{{V}helio.}> = -18.56 km s-1 (σ = 10.21 km s-1) and < [Fe/H]> = -0.68 (σ = 0.08), respectively, in agreement with previous literature estimates. The average [Na/Fe] abundance is 0.12 dex lower in the 47 Tuc AGB sample compared to the RGB sample, and the ratio of Na-poor to Na-rich stars is 63:37 on the AGB and 45:55 on the RGB. However, in contrast to NGC 6752, the two 47 Tuc populations have nearly identical [Na/Fe] dispersion and interquartile range values. The data presented here suggest that only a small fraction (≲20%) of Na-rich stars in 47 Tuc may fail to ascend the AGB, which is a similar result to that observed in M13. Regardless of the cause for the lower average [Na/Fe] abundance in AGB stars, we find that Na-poor stars and at least some Na-rich stars in 47 Tuc evolve through the early AGB phase. The contrasting behavior of Na-rich stars in 47 Tuc and NGC 6752 suggests that the RGB [Na/Fe] abundance alone is insufficient for predicting if a star will ascend the AGB.
Age ratios and their possible use in determining autumn routes of passerine migrants
C. John Ralph
1981-01-01
Age ratios and abundance of 61 migrant passerine species comprising more than 42,000 birds were analyzed in an attempt to determine patterns of migration. The data were collected at 10 stations from coastal Massachusetts to inland Pennsylvania. Age ratios are thought to be useful in determining routes of migration. The principal criteria for the edge of a species...
Chu, Jinyu; Zhang, Jinping; Zhou, Xiaohong; Liu, Biao; Li, Yimin
2015-09-01
Quantitative polymerase chain reaction (qPCR) assays and 16S rRNA gene clone libraries were used to document the abundance, diversity and community structure of anaerobic ammonia-oxidising (anammox) bacteria in the rhizosphere and non-rhizosphere sediments of three emergent macrophyte species (Iris pseudacorus, Thalia dealbata and Typha orientalis). The qPCR results confirmed the existence of anammox bacteria (AMX) with observed log number of gene copies per dry gram sediment ranging from 5.00 to 6.78. AMX was more abundant in T. orientalis-associated sediments than in the other two plant species. The I. pseudacorus- and T. orientalis-associated sediments had higher Shannon diversity values, indicating higher AMX diversity in these sediments. Based on the 16S rRNA gene, Candidatus 'Brocadia', Candidatus 'Kuenenia', Candidatus 'Jettenia' and new clusters were observed with the predominant Candidatus 'Kuenenia' cluster. The I. pseudacorus-associated sediments contained all the sequences of the C. 'Jettenia' cluster. Sequences obtained from T. orientalis-associated sediments contributed more than 90 % sequences in the new cluster, whereas none was found from I. pseudacorus. The new cluster was distantly related to known sequences; thus, this cluster was grouped outside the known clusters, indicating that the new cluster may be a new Planctomycetales genus. Further studies should be undertaken to confirm this finding.
Feng, Xiuyan; Zhang, Yiqian; Shao, Ningjun; Wang, Yanhui; Zhuang, Zhizhi; Wu, Ping; Lee, Matthew J; Liu, Yingli; Wang, Xiaonan; Zhuang, Jieqiu; Delpire, Eric; Gu, Dingying; Cai, Hui
2015-05-15
Thiazide-sensitive sodium chloride cotransporter (NCC) plays an important role in maintaining blood pressure. Aldosterone is known to modulate NCC abundance. Previous studies reported that dietary salts modulated NCC abundance through either WNK4 [with no lysine (k) kinase 4]-SPAK (Ste20-related proline alanine-rich kinase) or WNK4-extracellular signal-regulated kinase-1 and -2 (ERK1/2) signaling pathways. To exclude the influence of SPAK signaling pathway on the role of the aldosterone-mediated ERK1/2 pathway in NCC regulation, we investigated the effects of dietary salt changes and aldosterone on NCC abundance in SPAK knockout (KO) mice. We found that in SPAK KO mice low-salt diet significantly increased total NCC abundance while reducing ERK1/2 phosphorylation, whereas high-salt diet decreased total NCC while increasing ERK1/2 phosphorylation. Importantly, exogenous aldosterone administration increased total NCC abundance in SPAK KO mice while increasing DUSP6 expression, an ERK1/2-specific phosphatase, and led to decreasing ERK1/2 phosphorylation without changing the ratio of phospho-T53-NCC/total NCC. In mouse distal convoluted tubule (mDCT) cells, aldosterone increased DUSP6 expression while reducing ERK1/2 phosphorylation. DUSP6 Knockdown increased ERK1/2 phosphorylation while reducing total NCC expression. Inhibition of DUSP6 by (E)-2-benzylidene-3-(cyclohexylamino)-2,3-dihydro-1H-inden-1-one increased ERK1/2 phosphorylation and reversed the aldosterone-mediated increments of NCC partly by increasing NCC ubiquitination. Therefore, these data suggest that aldosterone modulates NCC abundance via altering NCC ubiquitination through a DUSP6-dependent ERK1/2 signal pathway in SPAK KO mice and part of the effects of dietary salt changes may be mediated by aldosterone in the DCTs.
Feng, Xiuyan; Zhang, Yiqian; Shao, Ningjun; Wang, Yanhui; Zhuang, Zhizhi; Wu, Ping; Lee, Matthew J.; Liu, Yingli; Wang, Xiaonan; Zhuang, Jieqiu; Delpire, Eric; Gu, Dingying
2015-01-01
Thiazide-sensitive sodium chloride cotransporter (NCC) plays an important role in maintaining blood pressure. Aldosterone is known to modulate NCC abundance. Previous studies reported that dietary salts modulated NCC abundance through either WNK4 [with no lysine (k) kinase 4]-SPAK (Ste20-related proline alanine-rich kinase) or WNK4-extracellular signal-regulated kinase-1 and -2 (ERK1/2) signaling pathways. To exclude the influence of SPAK signaling pathway on the role of the aldosterone-mediated ERK1/2 pathway in NCC regulation, we investigated the effects of dietary salt changes and aldosterone on NCC abundance in SPAK knockout (KO) mice. We found that in SPAK KO mice low-salt diet significantly increased total NCC abundance while reducing ERK1/2 phosphorylation, whereas high-salt diet decreased total NCC while increasing ERK1/2 phosphorylation. Importantly, exogenous aldosterone administration increased total NCC abundance in SPAK KO mice while increasing DUSP6 expression, an ERK1/2-specific phosphatase, and led to decreasing ERK1/2 phosphorylation without changing the ratio of phospho-T53-NCC/total NCC. In mouse distal convoluted tubule (mDCT) cells, aldosterone increased DUSP6 expression while reducing ERK1/2 phosphorylation. DUSP6 Knockdown increased ERK1/2 phosphorylation while reducing total NCC expression. Inhibition of DUSP6 by (E)-2-benzylidene-3-(cyclohexylamino)-2,3-dihydro-1H-inden-1-one increased ERK1/2 phosphorylation and reversed the aldosterone-mediated increments of NCC partly by increasing NCC ubiquitination. Therefore, these data suggest that aldosterone modulates NCC abundance via altering NCC ubiquitination through a DUSP6-dependent ERK1/2 signal pathway in SPAK KO mice and part of the effects of dietary salt changes may be mediated by aldosterone in the DCTs. PMID:25761881
The abundance of interstellar oxygen toward Orion: Evidence for recent infall?
NASA Technical Reports Server (NTRS)
Meyer, David M.; Jura, M.; Hawkins, Isabel; Cardelli, Jason A.
1994-01-01
We present high S/N (greater than 800) Goddard High-Resolution Spectrograph (GHRS) observations of the weak interstellar O I lambda 1356 absorption in the low-density sight lines toward iota Ori and kappa Ori. By comparing these data with observations toward more reddened stars, we find no evidence of density-dependent depletion from the gas phase for oxygen. The derived total oxygen abundance (gas plus grains) towards iota Ori and kappa Ori is consistent with stellar and nebular determinations in Orion at a level that is one-half the solar value. We speculate that the O/H abundance ratio is lower in Orion compared to the Sun because the local Milky Way has suffered a recent infall of metal-poor material, perhaps from the Magellanic Stream.