Observed and theoretical variations of atmospheric ozone

NASA Technical Reports Server (NTRS)

London, J.

1976-01-01

Results are summarized from three areas of ozone research: (1) continued analysis of the global distribution of total ozone to extend the global ozone atlas to summarize 15 years (1957-72) of ground based observations; (2) analysis of balloon borne ozonesonde observations for Arosa, Switzerland, and Hohenpeissenberg, Germany (GFR); (3) contined processing of the (Orbiting Geophysical Observatory-4) satellite data to complete the analysis of the stratospheric ozone distribution from the available OGO-4 data. Results of the analysis of the total ozone observations indicated that the long term ozone variation have marked regional patterns and tend to alternate with season and hemisphere. It is becoming increasingly clear that these long period changes are associated with large scale variations in the general upper atmosphere circulation patterns.

Dust variations in the diffuse interstellar medium: constraints on Milky Way dust from Planck-HFI observations

NASA Astrophysics Data System (ADS)

Ysard, N.; Köhler, M.; Jones, A.; Miville-Deschênes, M.-A.; Abergel, A.; Fanciullo, L.

2015-05-01

could explain part of the variations in dust observations. Finally, we show that varying the composition of metallic nano-inclusions in the silicates cannot account for the variations, at the same time showing that the amount of FeS they contain cannot be > 50% by volume. Conclusions: With small variations in the dust properties, we are able to explain most of the variations in the dust emission observed by Planck-HFI in the diffuse ISM. We also find that the small realistic changes in the dust properties that we consider almost perfectly match the anti-correlation and scatter in the observed β - T relation.

Sensitivity of grassland plant community composition to spatial vs. temporal variation in precipitation

USDA-ARS?s Scientific Manuscript database

Climate gradients shape spatial variation in the richness and composition of plant communities. Given future predicted changes in climate means and variability, and likely regional variation in the magnitudes of these changes, it is important to determine how temporal variation in climate influences...

Variation in age composition among colony sizes in Cliff Swallows.

PubMed

Brown, Charles R; Roche, Erin A; Brown, Mary Bomberger

2014-09-01

Variation in group size is characteristic of most social species. The extent to which individuals sort among group sizes based on age may yield insight into why groups vary in size and the age-specific costs and benefits of different social environments. We investigated the age composition of Cliff Swallow ( Petrochelidon pyrrhonota ) colonies of different sizes over 18 years at a long-term study site in western Nebraska, USA. Using years elapsed since banding as a relative measure of age for over 194,000 birds, we found that the proportion of age-class-1 swallows (birds banded as nestlings or juveniles or adults in the year of banding) of both sexes increased in larger colonies and at colony sites becoming active later in the summer. Age composition was unrelated to how often a particular colony site was used. The effect of colony size most likely reflected the fact that older birds return to the same colony site in successive years even when the colony size there decreases, and that yearlings and immigrants benefit more from larger colonies than do older, more experienced individuals. The date effect probably resulted in part from later spring arrival by younger and/or immigrant swallows. At fumigated sites where ectoparasitic swallow bugs ( Oeciacus vicarius ) had been removed, age composition did not vary with either colony size or colony initiation date. The patterns reported here appear to be driven partially by the presence of ectoparasites and suggest that the hematophagous bugs influence variation in Cliff Swallow group composition. Our results are consistent with the hypothesis that variation in colony size reflects, in part, age-based sorting of individuals among groups.

Long-term variations of the upper atmosphere parameters on Rome ionosonde observations and their interpretation

NASA Astrophysics Data System (ADS)

Perrone, Loredana; Mikhailov, Andrey; Cesaroni, Claudio; Alfonsi, Lucilla; Santis, Angelo De; Pezzopane, Michael; Scotto, Carlo

2017-09-01

A recently proposed self-consistent approach to the analysis of thermospheric and ionospheric long-term trends has been applied to Rome ionosonde summer noontime observations for the (1957-2015) period. This approach includes: (i) a method to extract ionospheric parameter long-term variations; (ii) a method to retrieve from observed foF1 neutral composition (O, O2, N2), exospheric temperature, Tex and the total solar EUV flux with λ < 1050 Å; and (iii) a combined analysis of the ionospheric and thermospheric parameter long-term variations using the theory of ionospheric F-layer formation. Atomic oxygen, [O] and [O]/[N2] ratio control foF1 and foF2 while neutral temperature, Tex controls hmF2 long-term variations. Noontime foF2 and foF1 long-term variations demonstrate a negative linear trend estimated over the (1962-2010) period which is mainly due to atomic oxygen decrease after ˜1990. A linear trend in (δhmF2)11y estimated over the (1962-2010) period is very small and insignificant reflecting the absence of any significant trend in neutral temperature. The retrieved neutral gas density, ρ atomic oxygen, [O] and exospheric temperature, Tex long-term variations are controlled by solar and geomagnetic activity, i.e. they have a natural origin. The residual trends estimated over the period of ˜5 solar cycles (1957-2015) are very small (<0.5% per decade) and statistically insignificant.

Spatiotemporal variation of bacterial community composition and possible controlling factors in tropical shallow lagoons.

PubMed

Laque, Thaís; Farjalla, Vinicius F; Rosado, Alexandre S; Esteves, Francisco A

2010-05-01

Bacterial community composition (BCC) has been extensively related to specific environmental conditions. Tropical coastal lagoons present great temporal and spatial variation in their limnological conditions, which, in turn, should influence the BCC. Here, we sought for the limnological factors that influence, in space and time, the BCC in tropical coastal lagoons (Rio de Janeiro State, Brazil). The Visgueiro lagoon was sampled monthly for 1 year and eight lagoons were sampled once for temporal and spatial analysis, respectively. BCC was evaluated by bacteria-specific PCR-DGGE methods. Great variations were observed in limnological conditions and BCC on both temporal and spatial scales. Changes in the BCC of Visgueiro lagoon throughout the year were best related to salinity and concentrations of NO (3) (-) , dissolved phosphorus and chlorophyll-a, while changes in BCC between lagoons were best related to salinity and dissolved phosphorus concentration. Salinity has a direct impact on the integrity of the bacterial cell, and it was previously observed that phosphorus is the main limiting nutrient to bacterial growth in these lagoons. Therefore, we conclude that great variations in limnological conditions of coastal lagoons throughout time and space resulted in different BCCs and salinity and nutrient concentration, particularly dissolved phosphorus, are the main limnological factors influencing BCC in these tropical coastal lagoons.

Copernicus observations of Iota Herculis velocity variations

NASA Technical Reports Server (NTRS)

Rogerson, J. B., Jr.

1984-01-01

Observations of Iota Her at 109.61-109.67 nm obtained with the U1 channel of the Copernicus spectrophotometer at resolution 5 pm during 3.6 days in May, 1979, are reported. Radial-velocity variations are detected and analyzed as the sum of two sinusoids with frequencies 0.660 and 0.618 cycles/day and amplitudes 9.18 and 8.11 km/s, respectively. Weak evidence supporting the 13.9-h periodicity seen in line-profile variations by Smith (1978) is found.

Cassini UVIS Observations of the Io Plasma Torus. 3; Observations of Temporal and Azimuthal Variability

NASA Technical Reports Server (NTRS)

Steffl, A. J.; Delamere, P. A.; Bagenal, F.

2006-01-01

In this third paper in a series presenting observations by the Cassini Ultraviolet Imaging Spectrometer (UVIS) of the Io plasma torus, we show remarkable, though subtle, spatio-temporal variations in torus properties. The Io torus is found to exhibit significant, near sinusoidal variations in ion composition as a functions of azimuthal position. The azimuthal variation in composition is such that the mixing ratio of S II us strongly correlated with the mixing ratio of S III and the equatorial electron density and strongly anti-correlated with the mixing ratios of both S IV and O II and the equatorial electron temperature. Surprisingly, the azimuthal variation in ion composition is observed to have a period of 10.07 h -- 1.5% longer than the System III rotation period of Jupiter, yet 1.3% shorter than the System UV period defined by [Brown, M. E., 1995. J. Geophys. Res. 100, 21683-21696]. Although the amplitude of the azimuthal variation of S III and O II remained in the range of 2-5%, the amplitude of the S II and S IV compositional variation ranged between 5 and 25% during the UVIS observations. Furthermore, the amplitude of the azimuthal variations of S II and S IV appears to be modulated by its location in System III longitude, such that when the region of maximum S II mixing ration (minimum S IV mixing ratio) is aligned with a System III longitude of 200 deg +/-, the amplitude is a factor of 4 greater than when the variation is anti-aligned. This behavior can explain numerous, often apparently contradictory, observations of variations in the properties of the Io plasma torus with the System III and System IV coordinate systems.

Geography, Ethnicity or Subsistence-Specific Variations in Human Microbiome Composition and Diversity

PubMed Central

Gupta, Vinod K.; Paul, Sandip; Dutta, Chitra

2017-01-01

One of the fundamental issues in the microbiome research is characterization of the healthy human microbiota. Recent studies have elucidated substantial divergences in the microbiome structure between healthy individuals from different race and ethnicity. This review provides a comprehensive account of such geography, ethnicity or life-style-specific variations in healthy microbiome at five major body habitats—Gut, Oral-cavity, Respiratory Tract, Skin, and Urogenital Tract (UGT). The review focuses on the general trend in the human microbiome evolution—a gradual transition in the gross compositional structure along with a continual decrease in diversity of the microbiome, especially of the gut microbiome, as the human populations passed through three stages of subsistence like foraging, rural farming and industrialized urban western life. In general, gut microbiome of the hunter-gatherer populations is highly abundant with Prevotella, Proteobacteria, Spirochaetes, Clostridiales, Ruminobacter etc., while those of the urban communities are often enriched in Bacteroides, Bifidobacterium, and Firmicutes. The oral and skin microbiome are the next most diverse among different populations, while respiratory tract and UGT microbiome show lesser variations. Higher microbiome diversity is observed for oral-cavity in hunter-gatherer group with higher prevalence of Haemophilus than agricultural group. In case of skin microbiome, rural and urban Chinese populations show variation in abundance of Trabulsiella and Propionibacterium. On the basis of published data, we have characterized the core microbiota—the set of genera commonly found in all populations, irrespective of their geographic locations, ethnicity or mode of subsistence. We have also identified the major factors responsible for geography-based alterations in microbiota; though it is not yet clear which factor plays a dominant role in shaping the microbiome—nature or nurture, host genetics or his environment

Effects of temperature variations on guided waves propagating in composite structures

NASA Astrophysics Data System (ADS)

Shoja, Siavash; Berbyuk, Viktor; Boström, Anders

2016-04-01

Effects of temperature on guided waves propagating in composite materials is a well-known problem which has been investigated in many studies. The majority of the studies is focused on effects of high temperature. Understanding the effects of low temperature has major importance in composite structures and components which are operating in cold climate conditions such as e.g. wind turbines operating in cold climate regions. In this study first the effects of temperature variations on guided waves propagating in a composite plate is investigated experimentally in a cold climate chamber. The material is a common material used to manufacture rotor blades of wind turbines. The temperature range is 25°C to -25°C and effects of temperature variations on amplitude and phase shift of the received signal are investigated. In order to apply the effects of lowering the temperature on the received signal, the Baseline Signal Stretch (BSS) method is modified and used. The modification is based on decomposing the signal into symmetric and asymmetric modes and applying two different stretch factors on each of them. Finally the results obtained based on the new method is compared with the results of application of BSS with one stretch factor and experimental measurements. Comparisons show that an improvement is obtained using the BSS with the mode decomposition method at temperature variations of more than 25°C.

Regional Variations in Aleutian Magma Composition

NASA Astrophysics Data System (ADS)

Nye, C. J.

2008-12-01

This study is based on sample data spanning 20 years from USGS, UAF, and DGGS geologists too numerous to list here. The 2900-km long Aleutian arc contains more than 50 active and over 90 Holocene volcanoes. The arc is built on oceanic Bering-sea floor west of 166W and quasi-continental crust east of 166W. Over the past twenty years the Alaska Volcano Observatory has conducted baseline geologic mapping (or remapping) and volcanic-hazards studies of selected volcanoes - generally those targeted for geophysical monitoring. This marks the largest sustained effort to study Aleutian volcanoes in half a century; AVO scientists have logged as many as 700 person-days per field season. Geologic studies have resulted in comprehensive suites of stratigraphically constrained samples and more than 3500 new whole-rock analyses by XRF and ICP/MS from more than 30 centers, more than doubling the number of previously published analyses. Examination of the data for regional and inter-volcano variations yields a number of first-order observations. (1) The arc can be broadly divided into an eastern segment (east of 158W) of calcalkaline andesite stratocones; a central segment dominated by large, mafic, tholeiitic shield volcanoes and stratocones; and a western segment (west of 175W) of smaller volcanoes with variable morphologies and generally more andesitic compositions. (2) There are NO significant first-order compositional signals that coincide with the transition from oceanic to continental basement. (3) Individual volcanoes are often subtly distinct from neighbors, and those distinctions persist for the lifetime of the centers. (4) All centers, notably including the large basaltic centers of the central arc, are strongly affected by open-system processes significantly more complicated than mixing among sibling-fractionates of parental mafic magmas. (5) Petrogenetic pathways are long-lived; individual batches of magma are (generally) not. (6) Calcalkaline andesites have

Aerosol chemical composition at Cabauw, The Netherlands as observed in two intensive periods in May 2008 and March 2009

NASA Astrophysics Data System (ADS)

Mensah, A. A.; Holzinger, R.; Otjes, R.; Trimborn, A.; Mentel, Th. F.; ten Brink, H.; Henzing, B.; Kiendler-Scharr, A.

2012-05-01

Observations of aerosol chemical composition in Cabauw, the Netherlands, are presented for two intensive measurement periods in May 2008 and March 2009. Sub-micron aerosol chemical composition was measured by an Aerodyne Aerosol Mass Spectrometer (AMS) and is compared to observations from aerosol size distribution measurements as well as composition measurements with a Monitor for AeRosol and GAses (MARGA) based instrument and a Thermal-Desorption Proton-Transfer-Reaction Mass-Spectrometer (TD-PTR-MS). An overview of the data is presented and the data quality is discussed. In May 2008 enhanced pollution was observed with organics contributing 40% to the PM1 mass. In contrast the observed average mass loading was lower in March 2009 and a dominance of ammonium nitrate (42%) was observed. The semi-volatile nature of ammonium nitrate is evident in the diurnal cycles with maximum concentrations observed in the morning hours in May 2008 and little diurnal variation observed in March 2009. Size dependent composition data from AMS measurements are presented and show a dominance of organics in the size range below 200 nm. A higher O:C ratio of the organics is observed for May 2008 than for March 2009. Together with the time series of individual tracer ions this shows the dominance of OOA over HOA in May 2008.

Solar Energetic Particle Composition over Two Solar Cycles as Observed by the Ulysses/HISCALE and ACE/EPAM Pulse Height Analyzers.

NASA Astrophysics Data System (ADS)

Patterson, J. D.; Madanian, H.; Manweiler, J. W.; Lanzerotti, L. J.

2017-12-01

We present the compositional variation in the Solar Energetic Particle (SEP) population in the inner heliosphere over two solar cycles using data from the Ulysses Heliospheric Instrument for Spectra, Composition, and Anisotropy at Low Energies (HISCALE) and Advanced Composition Explorer (ACE) Electron Proton Alpha Monitor (EPAM). The Ulysses mission was active from late 1990 to mid-2009 in a heliopolar orbit inclined by 80° with a perihelion of 1.3 AU and an aphelion of 5.4 AU. The ACE mission has been active since its launch in late 1997 and is in a halo orbit about L1. These two missions provide a total of 27 years of continuous observation in the inner heliosphere with twelve years of simultaneous observation. HISCALE and EPAM data provide species-resolved differential flux and density of SEP between 0.5-5 MeV/nuc. Several ion species (He, C, O, Ne, Si, Fe) are identified using the Pulse Height Analyzer (PHA) system of the Composition Aperture for both instruments. The He density shows a noticeable increase at high solar activity followed by a moderate drop at the quiet time of the solar minimum between cycles 23 and 24. The density of heavier ions (i.e. O and Fe) change minimally with respect to the F10.7 index variations however, certain energy-specific count rates decrease during solar minimum. With Ulysses and ACE observing in different regions of the inner heliosphere, there are significant latitudinal differences in how the O/He ratios vary with the solar cycle. At solar minimum, there is reasonable agreement between the observations from both instruments. At solar max 23, the differences in composition over the course of the solar cycle, and as observed at different heliospheric locations can provide insight to the origins of and acceleration processes differentially affecting solar energetic ions.

Spatio-temporal variation of fish taxonomic composition in a South-East Asian flood-pulse system.

PubMed

Kong, Heng; Chevalier, Mathieu; Laffaille, Pascal; Lek, Sovan

2017-01-01

The Tonle Sap Lake (TSL) is a flood-pulse system. It is the largest natural lake in South-East Asia and constitutes one of the largest fisheries over the world, supporting the livelihood of million peoples. Nonetheless, the Mekong River Basin is changing rapidly due to accelerating water infrastructure development (hydropower, irrigation, flood control, and water supply) and climate change, bringing considerable modifications to the annual flood-pulse of the TSL. Such modifications are expected to have strong impacts on fish biodiversity and abundance. This paper aims to characterize the spatio-temporal variations of fish taxonomic composition and to highlights the underlying determinants of these variations. For this purpose, we used data collected from a community catch monitoring program conducted at six sites during 141 weeks, covering two full hydrological cycles. For each week, we estimated beta diversity as the total variance of the site-by-species community matrix and partitioned it into Local Contribution to Beta Diversity (LCBD) and Species Contribution to Beta Diversity (SCBD). We then performed multiple linear regressions to determine whether species richness, species abundances and water level explained the temporal variation in the contribution of site and species to beta diversity. Our results indicate strong temporal variation of beta diversity due to differential contributions of sites and species to the spatial variation of fish taxonomic composition. We further found that the direction, the shape and the relative effect of species richness, abundances and water level on temporal variation in LCBD and SCBD values greatly varied among sites, thus suggesting spatial variation in the processes leading to temporal variation in community composition. Overall, our results suggest that fish taxonomic composition is not homogeneously distributed over space and time and is likely to be impacted in the future if the flood-pulse dynamic of the system is

Compositional Variations of Titan's Impact Craters Indicates Active Surface Erosion

NASA Astrophysics Data System (ADS)

Werynski, Alyssa; Neish, Catherine; Le Gall, Alice; Janssen, Michael A.

2017-10-01

Titan’s crust is assumed to be mostly water-ice. However, the surface composition is not well constrained due to its thick atmosphere. Based on infrared and radiometry data, the surface appears enriched in organics, with only few areas showing evidence of exposed water-ice. Regions of water-ice enrichment include the rims and ejecta blankets of impact craters. This study utilizes these geologic features to examine compositional variations across Titan’s surface, and their subsequent modification due to erosional processes.Sixteen craters and their ejecta blankets were mapped on a Cassini RADAR mosaic. These features were selected because they are some of the best preserved craters on Titan. Composition was inferred from Cassini’s Visual and Infrared Mapping Spectrometer (VIMS) and 2-cm emissivity data from the Cassini radiometer. With VIMS, different compositional units were inferred from their reflectivity at specific wavelengths. With the emissivity data, high values suggest more organic-rich material, while lower values indicate strong volume scattering. Areas with low emissivity have been interpreted to be water-ice rich, as water-ice is a favorable medium for volume scattering.Results show fresher, well-preserved craters in the dunes regions have a low emissivity indicative of water-ice, and a VIMS spectrum consistent with an unknown material, possibly a mixture of water-ice and organics. As these craters erode over time, the VIMS spectra remain the same but the emissivity increases. Well-preserved craters in the mid-latitude plains show VIMS spectra and emissivity values consistent with water-ice. As these plain craters degrade, the VIMS spectra remain the same, but the emissivity increases. The differing VIMS signatures suggest more mixing with organics during the cratering event in the organic-rich dunes than the plains. The changes in emissivity over time are consistent with organic infilling of subsurface fractures in both regions, with limited

Tensile Properties and Deflection Temperature of Polypropylene/Sumberejo Kenaf Fiber Composites with Fiber Content Variation

NASA Astrophysics Data System (ADS)

Ollivia, S. L.; Juwono, A. L.; Roseno, Seto

2017-05-01

The use of synthetic fibers as reinforcement in composites has disadvantage which are unsustainable and an adverse impact on the environment. An alternative reinforcement for composites is natural fiber. Polypropylene and Sumberejo kenaf fibers were used respectively as the matrix and reinforcement. The aim of this research was to obtain the optimum tensile properties and deflection temperature with the variation of kenaf fiber fractions. Polypropylene/kenaf fiber composites were fabricated by hot press method. The kenaf fiber was soaked in NaOH solution before being used as the reinforcement and polypropylene was extruded before being used as the matrix. The weight fractions were varied to produce composites and pristine polypropylene samples were also prepared for comparison. The optimum tensile strength, modulus and deflection temperature were found in the composites with the 40 wt% kenaf fiber fraction with an increase up to 80% and 170% compared to the pristine polypropylene with the values of (60.3 ± 4,3) MPa and (159.1 ± 1,8) °C respectively. The Scanning Electron Microscope observation results in the fracture surface of the composites with the 40 wt% fiber fraction showed a relatively good bonding interface between fibers and the matrix and the failure modes were fiber breakage and matrix failures.

Observationally Constraining Gas Giant Composition via Their Host Star Abundances

NASA Astrophysics Data System (ADS)

Teske, Johanna; Thorngren, Daniel; Fortney, Jonathan

2018-01-01

While the photospheric abundances of the Sun match many rock-forming elemental abundances in the Earth to within 10 mol%, as well as in Mars, the Moon, and meteorites, the Solar System giant planets are of distinctly non-stellar composition — Jupiter's bulk metallicity (inferred from its bulk density, measured from spacecraft data) is ∼ x5-10 solar, and Saturn is ∼ x10-20 solar. This knowledge has led to dramatic advances in understanding models of core accretion, which now match the heavy element enrichment of each of the Solar System's giant planets. However, we have thus far lacked similar data for exoplanets to use as a check for formation and composition models over a much larger parameter space. Here we present a study of the host stars of a sample of cool transiting gas giants with measured bulk metal fractions (as in Thorngren et al. 2016) to better constrain the relation Zplanet/Zstar — giant exoplanet metal enrichment relative to the host star. We add a new dimension of chemical variation, measuring C, O, Mg, Si, Ni, and well as Fe (on which previous Zplanet/Zstar calculations were based). Our analysis provides the best constraints to date on giant exoplanet interior composition and how this relates to formation environment, and make testable predictions for JWST observations of exoplanet atmospheres.

Variation in the isotopic composition of striped weakfish Cynoscion guatucupa of the Southwest Atlantic Ocean in response to dietary shifts.

PubMed

Viola, M N Paso; Riccialdelli, L; Jaureguizar, A; Panarello, H O; Cappozzo, H L

2018-05-01

The aim of this study was to analyze the isotopic composition in muscle of striped weakfish Cynoscion guatucupa from Southwest Atlantic Ocean in order to evaluate a possible variation in δ13C and δ15N in response to dietary shifts that occur as animals grow. We also explored for isotopic evidence of differences between sample locations. The results showed an agreement between isotope analysis and previous conventional studies. Differences in the isotope composition between sampling location were not observed. A positive relation exists between isotope values and total body length of the animals. The Cluster analysis defined three groups of size classes, validated by the MDS. Differences in the relative consumption of prey species in each size class were also observed performing isotope mixing models (SIAR). Variation in δ15N among size classes would be associated with the consumption of a different type of prey as animals grow. Small striped weakfish feed on small crustaceans and progressively increase their consumption of fish (anchovy, Engraulis anchoita), increasing by this way their isotope values. On the other hand, differences in δ13C values seemed to be related to age-class specific spatial distribution patterns. Therefore, large and small striped weakfish remain specialized but feeding on different prey at different trophic levels. These results contribute to the study of the diet of striped weakfish, improve the isotopic ecology models and highlight on the importance of accounting for variation in the isotopic composition in response to dietary shifts with the size of one of the most important fishery resources in the region.

Controls over spatial and seasonal variations on isotopic composition of the precipitation along the central and eastern portion of Brazil.

PubMed

Gastmans, Didier; Santos, Vinícius; Galhardi, Juliana Aparecida; Gromboni, João Felipe; Batista, Ludmila Vianna; Miotlinski, Konrad; Chang, Hung Kiang; Govone, José Silvio

2017-10-01

Based on Global Network Isotopes in Precipitation (GNIP) isotopic data set, a review of the spatial and temporal variability of δ 18 O and δ 2 H in precipitation was conducted throughout central and eastern Brazil, indicating that dynamic interactions between Intertropical and South Atlantic Convergence Zones, Amazon rainforest, and Atlantic Ocean determine the variations on the isotopic composition of precipitation over this area. Despite the seasonality and latitude effects observed, a fair correlation with precipitation amount was found. In addition, Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) air mass back trajectories were used to quantify the factors controlling daily variability in stable isotopes in precipitation. Through a linear multiple regression analysis, it was observed that temporal variations were consistent with the meteorological parameters derived from HYSPLIT, particularly precipitation amount along the trajectory and mix depth, but are not dependent on vapour residence time in the atmosphere. These findings also indicate the importance of convective systems to control the isotopic composition of precipitation in tropical and subtropical regions.

Variations in the abundance of iron on Mercury's surface from MESSENGER X-Ray Spectrometer observations

NASA Astrophysics Data System (ADS)

Weider, Shoshana Z.; Nittler, Larry R.; Starr, Richard D.; McCoy, Timothy J.; Solomon, Sean C.

2014-06-01

We present measurements of Mercury's surface composition from the analysis of MESSENGER X-Ray Spectrometer data acquired during 55 large solar flares, which each provide a statistically significant detection of Fe X-ray fluorescence. The Fe/Si data display a clear dependence on phase angle, for which the results are empirically corrected. Mercury's surface has a low total abundance of Fe, with a mean Fe/Si ratio of ˜0.06 (equivalent to ˜1.5 wt% Fe). The absolute Fe/Si values are subject to a number of systematic uncertainties, including the phase-angle correction and possible mineral mixing effects. Individual Fe/Si measurements have an intrinsic error of ˜10%. Observed Fe/Si values display small variations (significant at two standard deviations) from the planetary average value across large regions in Mercury's southern hemisphere. Larger differences are observed between measured Fe/Si values from more spatially resolved footprints on volcanic smooth plains deposits in the northern hemisphere and from those in surrounding terrains. Fe is most likely contained as a minor component in sulfide phases (e.g., troilite, niningerite, daubréelite) and as Fe metal, rather than within mafic silicates. Variations in surface reflectance (i.e., differences in overall reflectance and spectral slope) across Mercury are unlikely to be caused by variations in the abundance of Fe.

Global variations in abyssal peridotite compositions

NASA Astrophysics Data System (ADS)

Warren, Jessica M.

2016-04-01

Abyssal peridotites are ultramafic rocks collected from mid-ocean ridges that are the residues of adiabatic decompression melting. Their compositions provide information on the degree of melting and melt-rock interaction involved in the formation of oceanic lithosphere, as well as providing constraints on pre-existing mantle heterogeneities. This review presents a compilation of abyssal peridotite geochemical data (modes, mineral major elements, and clinopyroxene trace elements) for > 1200 samples from 53 localities on 6 major ridge systems. On the basis of composition and petrography, peridotites are classified into one of five lithological groups: (1) residual peridotite, (2) dunite, (3) gabbro-veined and/or plagioclase-bearing peridotite, (4) pyroxenite-veined peridotite, and (5) other types of melt-added peridotite. Almost a third of abyssal peridotites are veined, indicating that the oceanic lithospheric mantle is more fertile, on average, than estimates based on residual peridotites alone imply. All veins appear to have formed recently during melt transport beneath the ridge, though some pyroxenites may be derived from melting of recycled oceanic crust. A limited number of samples are available at intermediate and fast spreading rates, with samples from the East Pacific Rise indicating high degrees of melting. At slow and ultra-slow spreading rates, residual abyssal peridotites define a large (0-15% modal clinopyroxene and spinel Cr# = 0.1-0.6) compositional range. These variations do not match the prediction for how degree of melting should vary as a function of spreading rate. Instead, the compositional ranges of residual peridotites are derived from a combination of melting, melt-rock interaction and pre-existing compositional variability, where melt-rock interaction is used here as a general term to refer to the wide range of processes that can occur during melt transport in the mantle. Globally, 10% of abyssal peridotites are refractory (0% clinopyroxene

Growth and Characterization of Chalcogenide Alloy Nanowires with Controlled Spatial Composition Variation for Optoelectronic Applications

NASA Astrophysics Data System (ADS)

Nichols, Patricia

The energy band gap of a semiconductor material critically influences the operating wavelength of an optoelectronic device. Realization of any desired band gap, or even spatially graded band gaps, is important for applications such as lasers, light-emitting diodes (LEDs), solar cells, and detectors. Compared to thin films, nanowires offer greater flexibility for achieving a variety of alloy compositions. Furthermore, the nanowire geometry permits simultaneous incorporation of a wide range of compositions on a single substrate. Such controllable alloy composition variation can be realized either within an individual nanowire or between distinct nanowires across a substrate. This dissertation explores the control of spatial composition variation in ternary alloy nanowires. Nanowires were grown by the vapor-liquid-solid (VLS) mechanism using chemical vapor deposition (CVD). The gas-phase supersaturation was considered in order to optimize the deposition morphology. Composition and structure were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy (EDS), and x-ray diffraction (XRD). Optical properties were investigated through photoluminescence (PL) measurements. The chalcogenides selected as alloy endpoints were lead sulfide (PbS), cadmium sulfide (CdS), and cadmium selenide (CdSe). Three growth modes of PbS were identified, which included contributions from spontaneously generated catalyst. The resulting wires were found capable of lasing with wavelengths over 4000 nm, representing the longest known wavelength from a sub-wavelength wire. For CdxPb1-xS nanowires, it was established that the cooling process significantly affects the alloy composition and structure. Quenching was critical to retain metastable alloys with x up to 0.14, representing a new composition in nanowire form. Alternatively, gradual cooling caused phase segregation, which created heterostructures with light emission in

The Composition of M-type Asteroids: Synthesis of Spectroscopic and Radar Observations.

NASA Astrophysics Data System (ADS)

Bell, Maureen; Clark, B. E.; Shepard, M. K.; Issacs, R. A.; Cloutis, E. A.; Fornasier, S.; Bus, S. J.

2010-10-01

We have conducted a radar-driven observational campaign of 22 main-belt asteroids (MBAs) focused on Bus-DeMeo Xc- and Xk-type objects (Tholen X and M class asteroids) using the Arecibo radar and NASA Infrared Telescope Facilities (IRTF). Sixteen of our targets were near-simultaneously observed with radar. We find that most of the highest metal-content asteroids, as suggested by radar, tend to exhibit silicate absorption features at both 0.9 and 1.9 microns, and the lowest metal-content asteroids tend to exhibit either no bands or only the 0.9 microns band. Eleven of the asteroids were observed at several rotational longitudes in the near-infrared and significant variations in continuum slope were found for nine in the spectral regions 1.1-1.45 microns and 1.6-2.3 microns. Compositional evidence is derived from our target asteroid spectra using two different methods: 1) a Chi-squared search for spectral matches in the RELAB database, and 2) parametric comparisons with meteorites. We find that for four of the seven asteroids with the highest iron abundances, our spectral results are consistent with each other and with the radar evidence pointing to an iron meteorite composition (16 Psyche, 216 Kleopatra, 347 Pariana, and 779 Nina). Four asteroids have radar analogs consistent with either our parametric comparison or our RELAB analog type (21 Lutetia, 135 Hertha, 497 Iva, and 758 Mancunia ). The remaining eight asteroids (22 Kalliope, 97 Klotho, 110 Lydia, 129 Antigone, 224 Oceana, 678 Fredegundis, 771 Libera, and 785 Zwetana) have ambiguous compositional interpretations when comparing the spectral analogs to the radar analogs.

Variation in the Composition and In Vitro Proinflammatory Effect of Urban Particulate Matter from Different Sites

PubMed Central

Manzano-León, Natalia; Quintana, Raúl; Sánchez, Brisa; Serrano, Jesús; Vega, Elizabeth; Vázquez-López, Inés; Rojas-Bracho, Leonora; López-Villegas, Tania; O’Neill, Marie S.; Vadillo-Ortega, Felipe; De Vizcaya-Ruiz, Andrea; Rosas, Irma

2015-01-01

Spatial variation in particulate matter–related health and toxicological outcomes is partly due to its composition. We studied spatial variability in particle composition and induced cellular responses in Mexico City to complement an ongoing epidemiologic study. We measured elements, endotoxins, and polycyclic aromatic hydrocarbons in two particle size fractions collected in five sites. We compared the in vitro proinflammatory response of J774A.1 and THP-1 cells after exposure to particles, measuring subsequent TNFα and IL-6 secretion. Particle composition varied by site and size. Particle constituents were subjected to principal component analysis, identifying three components: C1 (Si, Sr, Mg, Ca, Al, Fe, Mn, endotoxin), C2 (polycyclic aromatic hydrocarbons), and C3 (Zn, S, Sb, Ni, Cu, Pb). Induced TNFα levels were higher and more heterogeneous than IL-6 levels. Cytokines produced by both cell lines only correlated with C1, suggesting that constituents associated with soil induced the inflammatory response and explain observed spatial differences. PMID:23335408

Variation in the terrestrial isotopic composition and atomic weight of argon

USGS Publications Warehouse

Böhlke, John Karl

2014-01-01

The isotopic composition and atomic weight of argon (Ar) are variable in terrestrial materials. Those variations are a source of uncertainty in the assignment of standard properties for Ar, but they provide useful information in many areas of science. Variations in the stable isotopic composition and atomic weight of Ar are caused by several different processes, including (1) isotope production from other elements by radioactive decay (radiogenic isotopes) or other nuclear transformations (e.g., nucleogenic isotopes), and (2) isotopic fractionation by physical-chemical processes such as diffusion or phase equilibria. Physical-chemical processes cause correlated mass-dependent variations in the Ar isotope-amount ratios (40Ar/36Ar, 38Ar/36Ar), whereas nuclear transformation processes cause non-mass-dependent variations. While atmospheric Ar can serve as an abundant and homogeneous isotopic reference, deviations from the atmospheric isotopic ratios in other Ar occurrences limit the precision with which a standard atomic weight can be given for Ar. Published data indicate variation of Ar atomic weights in normal terrestrial materials between about 39.7931 and 39.9624. The upper bound of this interval is given by the atomic mass of 40Ar, as some samples contain almost pure radiogenic 40Ar. The lower bound is derived from analyses of pitchblende (uranium mineral) containing large amounts of nucleogenic 36Ar and 38Ar. Within this interval, measurements of different isotope ratios (40Ar/36Ar or 38Ar/36Ar) at various levels of precision are widely used for studies in geochronology, water–rock interaction, atmospheric evolution, and other fields.

Study of variation in surface morphology, chemical composition, crystallinity and hardness of laser irradiated silver in dry and wet environments

NASA Astrophysics Data System (ADS)

Ali, Nisar; Bashir, Shazia; Umm-i-Kalsoom; Begum, Narjis; Hussain, Tousif

2017-07-01

Variation in surface morphology, chemical composition, crystallinity and hardness of laser irradiated silver in dry and wet ambient environments has been investigated. For this purpose, the silver targets were exposed for various number of laser pulses in ambient environment of air, ethanol and de-ionized water for various number of laser pulses i.e. 500, 1000, 1500 and 2000. Scanning Electron Microscope (SEM) was employed to investigate the surface morphology of irradiated silver. SEM analysis reveals significant surface variations for both dry and wet ambient environments. For lower number of pulses, in air environment significant mass removal is observed but in case of ethanol no significant change in surface morphology is observed. In case of de-ionized water small sized cavities are observed with formation of protrusions with spherical top ends. For higher number of laser pulses, refilling of cavities by shock liquefied material, globules and protrusions are observed in case of dry ablation. For ablation in ethanol porous and coarse periodic ripples are observed whereas, for de-ionized water increasing density of protrusions is observed for higher number of pulses. EDS analysis exhibits the variation in chemical composition along with an enhanced diffusion of oxygen under both ambient conditions. The crystal structure of the exposed targets were explored by X-ray Diffraction (XRD) technique. XRD results support the EDS results. Formation of Ag2O in case of air and ethanol whereas, Ag2O and Ag3O in case of de-ionized water confirms the diffusion of oxygen into the silver surface after irradiation. Vickers Hardness tester was employed to measure the hardness of laser treated targets. Enhanced hardness is observed after irradiation in both dry and wet ambient environments. Initial decrease and then increase in hardness is observed with increase in number of laser pulses in air environment. In case of ethanol, increase in number of laser pulses results in

Variation in coastal Antarctic microbial community composition at sub-mesoscale: spatial distance or environmental filtering?

PubMed

Moreno-Pino, Mario; De la Iglesia, Rodrigo; Valdivia, Nelson; Henríquez-Castilo, Carlos; Galán, Alexander; Díez, Beatriz; Trefault, Nicole

2016-07-01

Spatial environmental heterogeneity influences diversity of organisms at different scales. Environmental filtering suggests that local environmental conditions provide habitat-specific scenarios for niche requirements, ultimately determining the composition of local communities. In this work, we analyze the spatial variation of microbial communities across environmental gradients of sea surface temperature, salinity and photosynthetically active radiation and spatial distance in Fildes Bay, King George Island, Antarctica. We hypothesize that environmental filters are the main control of the spatial variation of these communities. Thus, strong relationships between community composition and environmental variation and weak relationships between community composition and spatial distance are expected. Combining physical characterization of the water column, cell counts by flow cytometry, small ribosomal subunit genes fingerprinting and next generation sequencing, we contrast the abundance and composition of photosynthetic eukaryotes and heterotrophic bacterial local communities at a submesoscale. Our results indicate that the strength of the environmental controls differed markedly between eukaryotes and bacterial communities. Whereas eukaryotic photosynthetic assemblages responded weakly to environmental variability, bacteria respond promptly to fine-scale environmental changes in this polar marine system. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Seasonal variations of Mercury's magnesium dayside exosphere from MESSENGER observations

NASA Astrophysics Data System (ADS)

Merkel, Aimee W.; Cassidy, Timothy A.; Vervack, Ronald J.; McClintock, William E.; Sarantos, Menelaos; Burger, Matthew H.; Killen, Rosemary M.

2017-01-01

The Ultraviolet and Visible Spectrometer channel of the Mercury Atmospheric and Surface Composition Spectrometer instrument aboard the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft made near-daily observations of solar-scattered resonant emission from magnesium in Mercury's exosphere during the mission's orbital phase (March 2011-April 2015, ∼17 Mercury years). In this paper, a subset of these data (March 2013-April 2015) is described and analyzed to illustrate Mg's spatial and temporal variations. Dayside altitude profiles of emission are used to make estimates of the Mg density and temperature. The main characteristics of the Mg exosphere are (a) a predominant enhancement of emission in the morning (6 am-10 am) near perihelion, (b) a bulk temperature of ∼6000 K, consistent with impact vaporization as the predominant ejection process, (c) a near-surface density that varies from 5 cm-3 to 50 cm-3 and (d) a production rate that is strongest in the morning on the inbound leg of Mercury's orbit with rates ranging from 1 × 105 cm-2 s-1 to 8 × 105 cm-2 s-1.

Variation in photosynthetic and nonphotosynthetic vegetation along edaphic and compositional gradients in northwestern Amazonia

NASA Astrophysics Data System (ADS)

Higgins, M. A.; Asner, G. P.; Perez, E.; Elespuru, N.; Alonso, A.

2014-03-01

Tropical forests vary substantially in aboveground properties such as canopy height, canopy structure, and plant species composition, corresponding to underlying variations in soils and geology. Forest properties are often difficult to detect and map in the field, however, due to the remoteness and inaccessibility of these forests. Spectral mixture analysis of Landsat imagery allows mapping of photosynthetic and nonphotosynthetic vegetation quantities (PV and NPV), corresponding to biophysical properties such as canopy openness, forest productivity, and disturbance. Spectral unmixing has been used for applications ranging from deforestation monitoring to identifying burn scars from past fires, but little is known about variations in PV and NPV in intact rainforest. Here we use spectral unmixing of Landsat imagery to map PV and NPV in northern Amazonia, and to test their relationship to soils and plant species composition. To do this we sampled 117 sites crossing a geological boundary in northwestern Amazonia for soil cation concentrations and plant species composition. We then used the Carnegie Landsat Analysis System to map PV and NPV for these sites from multiple dates of Landsat imagery. We found that soil cation concentrations and plant species composition consistently explain a majority of the variation in remotely sensed PV and NPV values. After combining PV and NPV into a single variable (PV-NPV), we determined that the influence of soil properties on canopy properties was inseparable from the influence of plant species composition. In all cases, patterns in PV and NPV corresponded to underlying geological patterns. Our findings suggest that geology and soils regulate canopy PV and NPV values in intact tropical forest, possibly through changes in plant species composition.

Variation in photosynthetic and nonphotosynthetic vegetation along edaphic and compositional gradients in northwestern Amazonia

NASA Astrophysics Data System (ADS)

Higgins, M. A.; Asner, G. P.; Perez, E.; Elespuru, N.; Alonso, A.

2014-07-01

Tropical forests vary substantially in aboveground properties such as canopy height, canopy structure, and plant species composition, corresponding to underlying variations in soils and geology. Forest properties are often difficult to detect and map in the field, however, due to the remoteness and inaccessibility of these forests. Spectral mixture analysis of Landsat imagery allows mapping of photosynthetic and nonphotosynthetic vegetation quantities (PV and NPV), corresponding to biophysical properties such as canopy openness, forest productivity, and disturbance. Spectral unmixing has been used for applications ranging from deforestation monitoring to identifying burn scars from past fires, but little is known about variations in PV and NPV in intact rainforests. Here we use spectral unmixing of Landsat imagery to map PV and NPV in northern Amazonia, and to test their relationship to soils and plant species composition. To do this we sampled 117 sites crossing a geological boundary in northwestern Amazonia for soil cation concentrations and plant species composition. We then used the Carnegie Landsat Analysis System to map PV and NPV for these sites from multiple dates of Landsat imagery. We found that soil cation concentrations and plant species composition consistently explain a majority of the variation in remotely sensed PV and NPV values. After combining PV and NPV into a single variable (PV-NPV), we determined that the influence of soil properties on canopy properties was inseparable from the influence of plant species composition. In all cases, patterns in PV and NPV corresponded to underlying geological patterns. Our findings suggest that geology and soils regulate canopy PV and NPV values in intact tropical forests, possibly through changes in plant species composition.

Variation in amino acid and lipid composition of latent fingerprints.

PubMed

Croxton, Ruth S; Baron, Mark G; Butler, David; Kent, Terry; Sears, Vaughn G

2010-06-15

The enhancement of latent fingerprints, both at the crime scene and in the laboratory using an array of chemical, physical and optical techniques, permits their use for identification. Despite the plethora of techniques available, there are occasions when latent fingerprints are not successfully enhanced. An understanding of latent fingerprint chemistry and behaviour will aid the improvement of current techniques and the development of novel ones. In this study the amino acid and fatty acid content of 'real' latent fingerprints collected on a non-porous surface was analysed by gas chromatography-mass spectrometry. Squalene was also quantified in addition. Hexadecanoic acid, octadecanoic acid and cis-9-octadecenoic acid were the most abundant fatty acids in all samples. There was, however, wide variation in the relative amounts of each fatty acid in each sample. It was clearly demonstrated that touching sebum-rich areas of the face immediately prior to fingerprint deposition resulted in a significant increase in the amount of fatty acids and squalene deposited in the resulting 'groomed' fingerprints. Serine was the most abundant amino acid identified followed by glycine, alanine and aspartic acid. The significant quantitative differences between the 'natural' and 'groomed' fingerprint samples seen for fatty acids were not observed in the case of the amino acids. This study demonstrates the variation in latent fingerprint composition between individuals and the impact of the sampling protocol on the quantitative analysis of fingerprints. (c) 2010 Elsevier Ireland Ltd. All rights reserved.

Applications of Satellite Observations of Tropospheric Composition

NASA Astrophysics Data System (ADS)

Monks, Paul S.; Beirle, Steffen

A striking feature of the field of tropospheric composition is the sheer number of chemical species that have been detected and measured with satellite instruments. The measurements have found application both in atmospheric chemistry itself, providing evidence, for example, of unexpected cryochemistry in the Arctic regions, and also in environmental monitoring with, for example, the observed growth in NO2 emissions over eastern Asia. Chapter 8 gives an overview of the utility of satellite observations for measuring tropospheric composition, dealing with each of the many compounds seen in detail. A comprehensive compound by compound table of the many studies performed is a most useful feature.

Elemental stoichiometry and compositions of weevil larvae and two acorn hosts under natural phosphorus variation

NASA Astrophysics Data System (ADS)

Ji, Huawei; Du, Baoming; Liu, Chunjiang

2017-04-01

To understand how different trophic organisms in a parasite food chain adapt to the differences in soil nutrient conditions, we investigated stoichiometric variation and homeostasis of multiple elements in two acorn trees, Quercus variabilis and Quercus acutissima, and their parasite weevil larvae (Curculio davidi Fairmaire) at phosphorus (P)-deficient and P-rich sites in subtropical China where P-rich ores are scattered among dominant P-deficient soils. Results showed that elemental stoichiometry and compositions of both acorns and weevil larvae differed significantly between P-deficient and P-rich sites (p < 0.05), with the largest contribution of acorn and weevil larva P in distinguishing the stoichiometric compositions between the two site types. The two acorn species were statistically separated by their acorn elemental stoichiometry and compositions (p < 0.05), but no difference was observed on weevil larvae between the two acorn species. P was one of the few elements that were non strict homeostasis in both acorns and weevil larvae. These findings highlight the importance of both environmental influence in elemental stoichiometry and composition and physiological regulations of nutritional needs in organisms and provide possible stoichiometric responses of both plants and animals to P loading, a worldwide issue from excess release of P into the environment.

Observing the variation of asteroid thermal inertia with heliocentric distance

NASA Astrophysics Data System (ADS)

Rozitis, B.; Green, S. F.; MacLennan, E.; Emery, J. P.

2018-06-01

Thermal inertia is a useful property to characterize a planetary surface, since it can be used as a qualitative measure of the regolith grain size. It is expected to vary with heliocentric distance because of its dependence on temperature. However, no previous investigation has conclusively observed a change in thermal inertia for any given planetary body. We have addressed this by using NEOWISE data and the Advanced Thermophysical Model to study the thermophysical properties of the near-Earth asteroids (1036) Ganymed, (1580) Betulia, and (276 049) 2002 CE26 as they moved around their highly eccentric orbits. We confirm that the thermal inertia values of Ganymed and 2002 CE26 do vary with heliocentric distance, although the degree of variation observed depends on the spectral emissivity assumed in the thermophysical modelling. We also confirm that the thermal inertia of Betulia did not change for three different observations obtained at the same heliocentric distance. Depending on the spectral emissivity, the variations for Ganymed and 2002 CE26 are potentially more extreme than that implied by theoretical models of heat transfer within asteroidal regoliths, which might be explained by asteroids having thermal properties that also vary with depth. Accounting for this variation reduces a previously observed trend of decreasing asteroid thermal inertia with increasing size, and suggests that the surfaces of small and large asteroids could be much more similar than previously thought. Furthermore, this variation can affect Yarkovsky orbital drift predictions by a few tens of per cent.

Intra-plant Variation in Nectar Sugar Composition in Two Aquilegia Species (Ranunculaceae): Contrasting Patterns under Field and Glasshouse Conditions

PubMed Central

Canto, Azucena; Pérez, Ricardo; Medrano, Mónica; Castellanos, María Clara; Herrera, Carlos M.

2007-01-01

Background and Aims Intra-specific variation in nectar chemistry under natural conditions has been only rarely explored, yet it is an essential aspect of our understanding of how pollinator-mediated selection might act on nectar traits. This paper examines intra-specific variation in nectar sugar composition in field and glasshouse plants of the bumblebee-pollinated perennial herbs Aquilegia vulgaris subsp. vulgaris and Aquilegia pyrenaica subsp. cazorlensis (Ranunculaceae). The aims of the study are to assess the generality of extreme intra-plant variation in nectar sugar composition recently reported for other species in the field, and gaining insight on the possible mechanisms involved. Methods The proportions of glucose, fructose and sucrose in single-nectary nectar samples collected from field and glasshouse plants were determined using high performance liquid chromatography. A hierarchical variance partition was used to dissect total variance into components due to variation among plants, flowers within plants, and nectaries within flowers. Key Results Nectar of the two species was mostly sucrose-dominated, but composition varied widely in the field, ranging from sucrose-only to fructose-dominated. Most intra-specific variance was due to differences among nectaries of the same flower, and flowers of the same plant. The high intra-plant variation in sugar composition exhibited by field plants vanished in the glasshouse, where nectar composition emerged as a remarkably constant feature across plants, flowers and nectaries. Conclusions In addition to corroborating the results of previous studies documenting extreme intra-plant variation in nectar sugar composition in the field, this study suggests that such variation may ultimately be caused by biotic factors operating on the nectar in the field but not in the glasshouse. Pollinator visitation and pollinator-borne yeasts are suggested as likely causal agents. PMID:17259227

Extracting Compositional Variation from THEMIS Data for Features with Large Topography on Mars Via Atmospheric Equalization

NASA Technical Reports Server (NTRS)

Anderson, F. S.; Drake, J. S.; Hamilton, V. E.

2005-01-01

We have developed a means of equalizing the atmospheric signature in Mars Odyssey Thermal Emission Imaging System (THEMIS) infrared data over regions with large topography such as the Valles Marineris (VM). This equalization allows for the analysis of compositional variations in regions that previously have been difficult to study because of the large differences in atmospheric path length that result from large changes in surface elevation. Specifically, our motivation for this study is to examine deposits that are small at the scales observable by the Thermal Emission Spectrometer (TES) onboard Mars Global Surveyor, but which are more readily resolved with THEMIS.

Titan's Surface Composition from Cassini VIMS Solar Occultation Observations

NASA Astrophysics Data System (ADS)

McCord, Thomas; Hayne, Paul; Sotin, Christophe

2013-04-01

Titan's surface is obscured by a thick absorbing and scattering atmosphere, allowing direct observation of the surface within only a few spectral win-dows in the near-infrared, complicating efforts to identify and map geologi-cally important materials using remote sensing IR spectroscopy. We there-fore investigate the atmosphere's infrared transmission with direct measure-ments using Titan's occultation of the Sun as well as Titan's reflectance measured at differing illumination and observation angles observed by Cas-sini's Visual and Infrared Mapping Spectrometer (VIMS). We use two im-portant spectral windows: the 2.7-2.8-mm "double window" and the broad 5-mm window. By estimating atmospheric attenuation within these windows, we seek an empirical correction factor that can be applied to VIMS meas-urements to estimate the true surface reflectance and map inferred composi-tional variations. Applying the empirical corrections, we correct the VIMS data for the viewing geometry-dependent atmospheric effects to derive the 5-µm reflectance and 2.8/2.7-µm reflectance ratio. We then compare the cor-rected reflectances to compounds proposed to exist on Titan's surface. We propose a simple correction to VIMS Titan data to account for atmospheric attenuation and diffuse scattering in the 5-mm and 2.7-2.8 mm windows, generally applicable for airmass < 3.0. We propose a simple correction to VIMS Titan data to account for atmospheric attenuation and diffuse scatter-ing in the 5-mm and 2.7-2.8 mm windows, generally applicable for airmass < 3.0. The narrow 2.75-mm absorption feature, dividing the window into two sub-windows, present in all on-planet measurements is not present in the occultation data, and its strength is reduced at the cloud tops, suggesting the responsible molecule is concentrated in the lower troposphere or on the sur-face. Our empirical correction to Titan's surface reflectance yields properties shifted closer to water ice for the majority of the low

Seasonal variations of Saanen goat milk composition and the impact of climatic conditions.

PubMed

Kljajevic, Nemanja V; Tomasevic, Igor B; Miloradovic, Zorana N; Nedeljkovic, Aleksandar; Miocinovic, Jelena B; Jovanovic, Snezana T

2018-01-01

The aim of this research was to investigate the effect of climatic conditions and their impact on seasonal variations of physico-chemical characteristics of Saanen goat milk produced over a period of 4 years. Lactation period (early, mid and late) and year were considered as factors that influence physico-chemical composition of milk. Pearson's coefficient of correlation was calculated between the physico-chemical characteristics of milk (fat, proteins, lactose, non-fat dry matter, density, freezing point, pH, titrable acidity) and climatic condition parameters (air temperature, temperature humidity index-THI, solar radiation duration, relative humidity). Results showed that all physico-chemical characteristics of Saanen goat milk varied significantly throughout the lactation period and years. The decrease of fat, protein, non-fat dry matter and lactose content in goat milk during the mid-lactation period was more pronounced than was previously reported in the literature. The highest values for these characteristics were recorded in the late lactation period. Observed variations were explained by negative correlation between THI and the physico-chemical characteristics of Saanen goat milk. This indicated that Saanen goats were very prone to heat stress, which implied the decrease of physico-chemical characteristics during hot summers.

Compositional variations on Mercury: Results from the Victoria quadrangle

NASA Astrophysics Data System (ADS)

Zambon, Francesca; Carli, Cristian; Galluzzi, Valentina; Capaccioni, Fabrizio; Giacomini, Lorenza; Massironi, Matteo; Palumbo, Pasquale; Cremonese, Gabriele

2017-04-01

Mercury was recently explored by the MESSENGER mission that orbited around the planet from March 2011 until April 2015 allowing a complete coverage of its surface. The Mercury Dual Imaging System (MDIS), mapped the Hermean surface at different spatial resolutions, due to variable altitude of the spacecraft from the surface. MDIS consists of two instruments: a Narrow Angle Camera (NAC) centered at 747nm, which acquired high-resolution images for the geological analysis, and the Wide Angle Camera (WAC), provided with 11 filters dedicated to the compositional analysis, operating in a range of wavelengths between 395 and 1040 nm. Mercury's surface has been divided into 15 quadrangles for mapping purposes. Here, we analyze the results obtained by the color composite mosaic of the quadrangle Victoria (H02) located at longitudes 270 ° - 360 ° E, and latitudes 22.5 ° N - 65 ° N. We produced a color mosaic, by using the images relative to the filters with the best spatial coverage. To obtain the 8-color mosaic of the Victoria quadrangle, we calibrated and georefenced the WAC raw images. Afterwards, we applied the Hapke photometric correction by using the parameters derived by Domingue et al. (2015). We projected and coregistered the data, and finally, we produced the mosaic. To analyze the compositional variations of the Victoria quadrangle, we consider different techniques of analysis, such as specific RGB color combinations and band ratios, which emphasize the different compositional characteristics of the surface. Furthermore, the use of clustering and classification methods allows for recognizing various terrain units, in terms of reflectance and spectral characteristics. In the H02 quadrangle, we observed a dichotomy in the RGB mosaic (R: second principal component (PC2), G: first principal component (PC1), B: 430/1000 nm; see Denevi et al. 2009) between the northern region of the quadrangle, dominated by smooth plains, and the southern part, characterized by

Seasonal Variations of Mercury's Magnesium Dayside Exosphere from MESSENGER Observations

NASA Technical Reports Server (NTRS)

Merkel, Aimee W.; Cassidy, Timothy A.; Vervack, Ronald J., Jr.; McClintock, William E.; Sarantos, Menelaos; Burger, Matthew H.; Killen, Rosemary M.

2017-01-01

The Ultraviolet and Visible Spectrometer channel of the Mercury Atmospheric and Surface Composition Spectrometer instrument aboard the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft made near-daily observations of solar-scattered resonant emission from magnesium in Mercury's exosphere during the mission's orbital phase (March 2011-April 2015, approx.17 Mercury years). In this paper, a subset of these data (March 2013-April 2015) is described and analyzed to illustrate Mg's spatial and temporal variations. Dayside altitude profiles of emission are used to make estimates of the Mg density and temperature. The main characteristics of the Mg exosphere are (a) a predominant enhancement of emission in the morning (6 am-10 am) near perihelion, (b) a bulk temperature of approx. 6000 K, consistent with impact vaporization as the predominant ejection process, (c) a near-surface density that varies from 5/cu cm to 50/cu cm and (d) a production rate that is strongest in the morning on the inbound leg of Mercury's orbit with rates ranging from 1×10(exp 5)/sq cm/s to 8×10(exp 5)/sq cm/s.

Nitrogen Isotopic Ratio in Jupiter's Atmosphere from Observations by Composite Infrared Spectrometer (CIRS) on the Cassini Spacecraft

NASA Technical Reports Server (NTRS)

Abbas, M. M.; LeClair, A.; Owen, T.; Conrath, B. J.; Flasar, F. M.; Kunde, V. G.; Nixon, C. A..; Achterberg, R. K.; Bjoraker, G.; Jennings, D. J.

2003-01-01

The Composite Infrared Spectrometer (CIRS) on the Cassini spacecraft made infrared observations of Jupiter's atmosphere during the flyby in December 2000 to January 2001. The unique database in the 600-1400/cm region with 0.53 and 2.8/cm spectral resolutions obtained from the observations permits retrieval of global maps of the thermal structure and composition of Jupiter's atmosphere including the distributions of (14)NH3 and (15)NH3. Analysis of Jupiter's ammonia distributions from three isolated (15)NH3 spectral lines in eight latitudes is presented for evaluation of the nitrogen isotopic ratio. The nitrogen isotopic ratio (14)N/(15)N (or (15)N/(14)N) in Jupiter's atmosphere in this analysis is calculated to be: 448 +/- 62 ((2.23 +/- 0.31) x 10(exp -3)). This value of the ratio determined from CIRS data is found to be in very close agreement with the value previously obtained from the measurements by the Galileo Probe Mass Spectrometer. Some possible mechanisms to account for the variation of Jupiter's observed isotopic ratio relative to various astrophysical environments are discussed.

Spectroscopic observations of spatial and temporal variations on Venus

NASA Technical Reports Server (NTRS)

Young, A. T.; Young, L. G.; Woszczyk, A.

1974-01-01

Details of the Table Mountain spectroscopic patrol of Venus in September-October 1972 are given. The data indicate systematic variation over the disc, with more CO2 absorption near the terminator than at the limb, and slightly more in the southern than in the northern hemisphere. The semiregular four-day variation, reported to occur simultaneously over the disk at 8689 A by Young et al. (1973), is confirmed by observations of the 7820 A and 7883 A CO2 bands.

Matrix cracking with irregular fracture fronts as observed in fiber reinforced ceramic composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, K.X.; Yeh, C.P.; Wyatt, K.W.

1998-01-01

As a result of matrix cracking in fiber reinforced composites, fracture planforms assume a wide variation of profiles due to the fact that fiber bridging strongly affects the behavior of local crack fronts. This observation raises the question on the legitimacy of commonly used penny-shaped crack solutions when applied to fiber reinforced composites. Accordingly, investigation of the effects of fracture front profiles on mechanical responses is the thrust of this paper. The authors start with the solution of a penny-shaped crack in a unidirectional, fiber reinforced composite, which demonstrates necessity of considering wavy fracture fronts in fiber reinforced composites. Amore » theoretical framework for fiber reinforced composites with irregular fracture fronts due to matrix cracking is then established via a micromechanics model. The difference between small crack-size matrix cracking and large crack-size matrix cracking is investigated in detail. It is shown that the bridging effect is insignificant when matrix crack size is small and solution of effective property are obtained using Mori-Tanaka`s method by treating cracks and reinforcing fibers as distinct, but interacting phases. When the crack size becomes large, the bridging effects has to be taken into consideration. With bridging tractions obtained in consistency with the micromechanics solution, and corresponding crack energy backed out, the effective properties are obtained through a modification of standard Mori-Tanaka`s treatment of multiphase composites. Analytical solutions show that the generalization of a crack density of a penny-shaped planform is insufficient in describing the effective responses of fiber-reinforced composites with matrix cracking. Approximate solutions that account for the effects of the irregularity of crack planforms are given in closed forms for several irregular crack planforms, including cracks of cross rectangle, polygon and rhombus.« less

Impact of the material composition on proton range variation - A Monte Carlo study

NASA Astrophysics Data System (ADS)

Wu, S. W.; Tung, C. J.; Lee, C. C.; Fan, K. H.; Huang, H. C.; Chao, T. C.

2015-11-01

In this study, we used the Geant4 toolkit to demonstrate the impacts of the material composition of tissues on proton range variation. Bragg curves of different materials subjected to a 250 MeV mono-energy proton beam were simulated and compared. These simulated materials included adipose, heart, brain, cartilage, cortical bone and water. The results showed that there was significant proton range deviation between Bragg curves, especially for cortical bone. The R50 values for a 250 MeV proton beam were approximately 39.55 cm, 35.52 cm, 37.00 cm, 36.51 cm, 36.72 cm, 22.53 cm, and 38.52 cm in the phantoms that were composed completely of adipose, cartilage, tissue, heart, brain, cortical bone, and water, respectively. Mass density and electron density were used to scale the proton range for each material; electron density provided better range scaling. In addition, a similar comparison was performed by artificially setting all material density to 1.0 g/cm3 to evaluate the range deviation due to chemical components alone. Tissue heterogeneity effects due to density variation were more significant, and less significant for chemical composition variation unless the Z/A was very different.

Joint inversion of shear wave travel time residuals and geoid and depth anomalies for long-wavelength variations in upper mantle temperature and composition along the Mid-Atlantic Ridge

NASA Technical Reports Server (NTRS)

Sheehan, Anne F.; Solomon, Sean C.

1991-01-01

Measurements were carried out for SS-S differential travel time residuals for nearly 500 paths crossing the northern Mid-Atlantic Ridge, assuming that the residuals are dominated by contributions from the upper mantle near the surface bounce point of the reflected phase SS. Results indicate that the SS-S travel time residuals decrease linearly with square root of age, to an age of 80-100 Ma, in general agreement with the plate cooling model. A joint inversion was formulated of travel time residuals and geoid and bathymetric anomalies for lateral variation in the upper mantle temperature and composition. The preferred inversion solutions were found to have variations in upper mantle temperature along the Mid-Atlantic Ridge of about 100 K. It was calculated that, for a constant bulk composition, such a temperature variation would produce about a 7-km variation in crustal thickness, larger than is generally observed.

The composition of M-type asteroids: Synthesis of spectroscopic and radar observations

NASA Astrophysics Data System (ADS)

Ockert-Bell, M. E.; Clark, B. E.; Shepard, M. K.; Isaacs, R. A.; Cloutis, E. A.; Fornasier, S.; Bus, S. J.

2010-12-01

We have conducted a radar-driven observational campaign of 22 main-belt asteroids (MBAs) focused on Bus-DeMeo Xc- and Xk-type objects (Tholen X and M class asteroids) using the Arecibo radar and NASA Infrared Telescope Facilities (IRTF). Sixteen of our targets were near-simultaneously observed with radar and those observations are described in a companion paper (Shepard, M.K., and 19 colleagues [2010]. Icarus, in press). We find that most of the highest metal-content asteroids, as suggested by radar, tend to exhibit silicate absorption features at both 0.9 and 1.9 μm, and the lowest metal-content asteroids tend to exhibit either no bands or only the 0.9 μm band. Eleven of the asteroids were observed at several rotational longitudes in the near-infrared and significant variations in continuum slope were found for nine in the spectral regions 1.1-1.45 μm and 1.6-2.3 μm. We utilized visible wavelength data (Bus, S.J., Binzel, R.P. [2002b]. Icarus 158, 146-177; Fornasier, S., Clark, B.E., Dotto, E., Migliorini, A., Ockert-Bell, M., Barucci, M.A. [2010]. Icarus 210, 655-673.) for a more complete compositional analysis of our targets. Compositional evidence is derived from our target asteroid spectra using two different methods: (1) a χ2 search for spectral matches in the RELAB database, and (2) parametric comparisons with meteorites. This paper synthesizes the results of the RELAB search and the parametric comparisons with compositional suggestions based on radar observations. We find that for six of the seven asteroids with the highest iron abundances, our spectral results are consistent with the radar evidence (16 Psyche, 216 Kleopatra, 347 Pariana, 758 Mancunia, 779 Nina, and 785 Zwetana). Three of the seven asteroids with the lowest metal abundances, our spectral results are consistent with the radar evidence (21 Lutetia, 135 Hertha, 497 Iva). The remaining seven asteroids (22 Kalliope, 97 Klotho, 110 Lydia, 129 Antigone, 224 Oceana, 678 Fredegundis, and 771

Using MLT Composition Observations to Evaluate Transport in a Comprehensive High Top Model

NASA Astrophysics Data System (ADS)

Smith, A. K.

2016-12-01

Gravity waves play an outsized role in the MLT: driving the mean meridional circulation, exerting a large degree of control over the mean winds and seasonal variations in temperature, and leading to diffusive vertical transport of heat and trace species. These waves are represented using a parameterization in the NCAR Whole Atmosphere Community Climate Model (WACCM), as in many other GCMs. To evaluate their impact, we need to consider not just the mean temperature and wind but the distributions of trace species that are affected by advection due to resolved winds and waves and diffusion associated with gravity wave dissipation. The responses of chemical species to changes in the gravity wave forcing are complex and sometimes unexpected. Transport and diffusion simultaneously affect all species and the heat and momentum budgets; subsequent interactions, and the strong dependence of reaction rates on temperature, affect the net impact of transport on the composition. In evaluating the model, we evaluate the simulations using a range of available observations of composition, including O, O3, CO, CO2, NO, NO2, OH, and H2O.

Linking variations in sea spray aerosol particle hygroscopicity to composition during two microcosm experiments

NASA Astrophysics Data System (ADS)

Forestieri, Sara D.; Cornwell, Gavin C.; Helgestad, Taylor M.; Moore, Kathryn A.; Lee, Christopher; Novak, Gordon A.; Sultana, Camille M.; Wang, Xiaofei; Bertram, Timothy H.; Prather, Kimberly A.; Cappa, Christopher D.

2016-07-01

correlation with the SSA NR-OM volume fractions after the peak of the blooms (i.e., Chl a maxima); i.e., the GF(85 %) values generally decreased when the NR-OM volume fractions increased. The GF(85 %) vs. NR-OM volume fraction relationship was interpreted using the Zdanovskii-Stokes-Robinson (ZSR) mixing rule and used to estimate the GF(85 %) of the organic matter in the nascent SSA. The estimated pure NR-OM GF(85 %) values were 1.16 ± 0.09 and 1.23 ± 0.10 for the indoor and outdoor MARTS, respectively. These measurements demonstrate a clear relationship between SSA particle composition and the sensitivity of light scattering to variations in relative humidity. The implications of these observations to the direct climate effects of SSA particles are discussed.

Variation of oil composition in vicinity of Arbuckle Mountains, Oklahoma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zemmels, I.; Walters, C.C.

1987-08-01

Fifteen oils in an 8-county area in the vicinity of the Arbuckle Mountains were classified into 6 oil types: stable platform type, Mill Creek syncline type, Joiner City field type, Gloeocapsamorpha type, Hoover field A-type; and Fitts field type. The stable platform, Mill Creek syncline, and Joiner City field types have a common element (diminished C/sub 32/ hopane) and are thought to be derived from distinctly different facies of the Woodford Formation. The Viola Limestone oil is typical of oil generated from Ordovician rocks. The Hoover field A-type has an element of Ordovician composition and is thought to have beenmore » derived from an Arbuckle Group shale. The Fitts field oil has a unique composition and has not been assigned to a source. The variation of oil composition in the vicinity of the Arbuckle Mountains is attributed to (1) the large number of potential source rocks, (2) the variety of facies going from the stable platform into the southern Oklahoma aulacogen, and (3) biodegradation of oils in shallow reservoirs.« less

A small variation in diet influences the Lactobacillus strain composition in the crop of broiler chickens.

PubMed

Hammons, Susan; Oh, Phaik Lyn; Martínez, Inés; Clark, Kenzi; Schlegel, Vicki L; Sitorius, Emily; Scheideler, Sheila E; Walter, Jens

2010-08-01

Feed composition has the potential to influence the activities of bacteria that colonize the digestive tract of broiler chickens with important consequences for animal health, well being, and food safety. In this study, the gut microbiota of two groups of broiler chickens raised in immediate vicinity but fed either a standard corn/soybean meal ration (corn-soy, CS) or a ration high in wheat middlings (high wheat, HW) was characterized. The findings revealed that this small variation in feed composition did not influence the distribution of microbial species present in the microbial community throughout the digestive tract. However, diet variation markedly influenced the Lactobacillus strain composition in the crop. Most striking, the dominant type in birds on the CS diet (Lactobacillus agilis type R5), which comprised 25% of the isolates, was not detected in birds fed the HW diet. The latter birds harbored a different strain of L. agilis (type R1) in a significantly higher ratio than birds on the CS diet. Several other strains were also specific to the particular diet. In conclusion, this study showed that a small variation in the composition of chicken feed that does not result in detectable differences in species composition can still have an impact on which microbial strains become dominant in the digestive tract. This finding has relevance in the application of probiotics and other direct-fed microbials in poultry husbandry. Copyright 2010 Elsevier GmbH. All rights reserved.

Telescope Array UHECR composition measurement via stereoscopic fluorescence observation

NASA Astrophysics Data System (ADS)

Stroman, Thomas; Bergman, Douglas; Telescope Array Collaboration

2016-03-01

When entering Earth's atmosphere at ultra-high energies, cosmic rays (UHECRs) produce extensive air showers whose longitudinal development is influenced by the incident primary particle's mass. Each longitudinal shower profile reaches its maximum particle count at an atmospheric slant depth Xmax, and the distributions of observed Xmax values can be compared to those predicted by detailed simulations of the air-shower physics and the detector; accurately simulated compositions that most closely resemble that found in nature will produce the best agreement between predicted and observed Xmax distributions. This is the basis of composition measurement at the Telescope Array experiment, the largest and most sensitive UHECR detector in the northern hemisphere. At the perimeter of a large surface-detector array are three fluorescence telescope stations, whose overlapping apertures enable high-precision reconstruction of Xmax from stereoscopic observation of air-shower longitudinal profiles. We present the distribution of Xmax observed during eight years of operation, and from comparisons with several simulated combinations of composition and high-energy hadronic physics, we show that a low primary mass is favored at E >10 18 . 2 eV.

A model for the temperature and composition effects in the semiannual variations of the thermospheric density

NASA Technical Reports Server (NTRS)

Mayr, H. G.; Volland, H.

1971-01-01

A model is proposed in which latitudinal variations in composition and temperature are used to interpret the semiannual effect in the thermospheric density. Two heat sources are postulated for the semiannual circulation: one at high latitudes associated with the semiannual component in the occurance of magnetic storms and a second weaker one that peaks at the equator associated with the semiannual migration between both hemispheres. Depending on the relative magnitude of these sources, the latitude regions in which composition and temperature effects dominate vary. The temperature effects however should be expected weakest at low to mid latitudes where the relative concentration of atomic oxygen is enriched during equinox. At high latitudes the semiannual temperature component would peak, associated with an oxygen depletion in the lower thermosphere during equinox. In combining these features it is shown that the total atmospheric density could still exhibit a relatively small latitude dependence in the semiannual component with the tendency to decrease at high latitudes, in agreement with observations.

Groundwater storage variations in the North China Plain using multiple space geodetic observations

NASA Astrophysics Data System (ADS)

Feng, W.; Longuevergne, L.; Kusche, J.; Liang, S.; Zhang, Y.; Scanlon, B. R.; Shum, C. K.; Yeh, P. J. F.; Long, D.; Cao, G.; Zhong, M.; Xu, H.; Xia, J.

2017-12-01

Water storage and pressure variations in the subsurface generate measurable gravity changes and surface displacements. This study presents the joint interpretation of GRACE and GPS/InSAR observations to better understand shallow and deep groundwater storage (GWS) variations associated with unsustainable pumping and impact of climate variability in the North China Plain (NCP). On seasonal timescales, GRACE-derived GWS variations are well explained by the combined effect of groundwater abstraction due to anthropogenic irrigation activities and groundwater recharge from natural precipitation. Interannual GWS variations in the NCP detected by GRACE is consistent with precipitation anomalies. During the drought years (e.g., 2002 and 2014), significant GWS depletion is detected by GRACE satellites. The GRACE-derived GWS variation rate is -8.0 ± 1.5 km3/yr during 2002-2014, which is significantly larger than the estimate from phreatic monitoring well observations. The difference between them indicates the significant GWS depletion in the confined deep aquifers of the NCP, generating large subsidence rates, which has been largely underestimated up to now. The GWS variation rate in deep aquifers estimated from GPS/InSAR observations can explain the difference between the GWS depletion rate from GRACE and that from well observations. Both GRACE and surface displacement offer significant potential to better understand water redistribution in shallow and deep aquifer systems of the NCP.

How well do satellite observations and models capture diurnal variation in aerosols over the Korean Peninsula?

NASA Astrophysics Data System (ADS)

Hyer, E. J.; Xian, P.; Campbell, J. R.

2016-12-01

Aerosol sources, sinks, and transport processes have important variations over the diurnal cycle. Advances in geostationary satellite observation have made it possible to retrieve aerosol properties over a larger fraction of the diurnal cycle in many areas. However, the conditions for retrieval of aerosol from space also have systematic diurnal variation, which must be considered when interpreting satellite data. We used surface PM2.5 observations from the Korean National Institute for Environmental Research, together with the dense network of AERONET sun photometers deployed in Korea for the KORUS-AQ mission in spring 2016, to examine diurnal variations in aerosol conditions and quantify the effect of systematic diurnal processes on daily integrated aerosol quantities of forcing and PM2.5 24-hour exposure. Time-resolved observations of aerosols from in situ data were compared to polar and geostationary satellite observations to evaluate these questions: 1) How well is diurnal variation observed in situ captured by satellite products? 2) Do the satellite products show evidence of systematic biases related to diurnally varying observing conditions? 3) What is the implication of diurnal variation for aerosol forcing estimates based on observations near solar noon? The diurnal variation diagnosed from observations was also compared to the output of the Navy Aerosol Analysis and Prediction System (NAAPS), to examine the ability of this model to capture aerosol diurnal variation. Finally, we discuss the implications of the observed diurnal variation for assimilation of aerosol observations into forecast models.

Using Space Lidar Observations to Decompose Longwave Cloud Radiative Effect Variations Over the Last Decade

NASA Astrophysics Data System (ADS)

Vaillant de Guélis, Thibault; Chepfer, Hélène; Noel, Vincent; Guzman, Rodrigo; Winker, David M.; Plougonven, Riwal

2017-12-01

Measurements of the longwave cloud radiative effect (LWCRE) at the top of the atmosphere assess the contribution of clouds to the Earth warming but do not quantify the cloud property variations that are responsible for the LWCRE variations. The CALIPSO space lidar observes directly the detailed profile of cloud, cloud opacity, and cloud cover. Here we use these observations to quantify the influence of cloud properties on the variations of the LWCRE observed between 2008 and 2015 in the tropics and at global scale. At global scale, the method proposed here gives good results except over the Southern Ocean. We find that the global LWCRE variations observed over ocean are mostly due to variations in the opaque cloud properties (82%); transparent cloud columns contributed 18%. Variation of opaque cloud cover is the first contributor to the LWCRE evolution (58%); opaque cloud temperature is the second contributor (28%).

Evaluation of indoor air composition time variation in air-tight occupied spaces during night periods

NASA Astrophysics Data System (ADS)

Markov, Detelin

2012-11-01

This paper presents an easy-to-understand procedure for prediction of indoor air composition time variation in air-tight occupied spaces during the night periods. The mathematical model is based on the assumptions for homogeneity and perfect mixing of the indoor air, the ideal gas model for non-reacting gas mixtures, mass conservation equations for the entire system and for each species, a model for prediction of basal metabolic rate of humans as well as a model for prediction of O2 consumption rate and both CO2 and H2O generation rates by breathing. Time variation of indoor air composition is predicted at constant indoor air temperature for three scenarios based on the analytical solution of the mathematical model. The results achieved reveal both the most probable scenario for indoor air time variation in air-tight occupied spaces as well as the cause for morning tiredness after having a sleep in a modern energy efficient space.

Direct estimation of tidally induced Earth rotation variations observed by VLBI

NASA Astrophysics Data System (ADS)

Englich, S.; Heinkelmann, R.; BOHM, J.; Schuh, H.

2009-09-01

The subject of our study is the investigation of periodical variations induced by solid Earth tides and ocean tides in Earth rotation parameters (ERP: polar motion, UT1)observed by VLBI. There are two strategies to determine the amplitudes and phases of Earth rotation variations from observations of space geodetic techniques. The common way is to derive time series of Earth rotation parameters first and to estimate amplitudes and phases in a second step. Results obtained by this means were shown in previous studies for zonal tidal variations (Englich et al.; 2008a) and variations caused by ocean tides (Englich et al.; 2008b). The alternative method is to estimate the tidal parameters directly within the VLBI data analysis procedure together with other parameters such as station coordinates, tropospheric delays, clocks etc. The purpose of this work was the application of this direct method to a combined VLBI data analysis using the software packages OCCAM (Version 6.1, Gauss-Markov-Model) and DOGSCS (Gerstl et al.; 2001). The theoretical basis and the preparatory steps for the implementation of this approach are presented here.

Variations in elemental composition of several MEV/nucleon ions observed in interplanetary space

NASA Technical Reports Server (NTRS)

Mcguire, R. E.; Vonrosenvinge, T. T.; Reames, D. V.

1985-01-01

Six years of accumulated ISEE-3 and IMP-8 data to study variations in elemental relative abundances among the different populations of energetic ions seen in interplanetary space are surveyed. Evidence suggesting that heavy ion enrichments may be organized by a rigidity scaling factor A/Z over the range H to Fe is presented. Data to support the hypothesis that shock-associated particles are probably accelerated from ambient energetic fluxes are shown.

Relationship between climatic variables and the variation in bulk tank milk composition using canonical correlation analysis.

PubMed

Stürmer, Morgana; Busanello, Marcos; Velho, João Pedro; Heck, Vanessa Isabel; Haygert-Velho, Ione Maria Pereira

2018-06-04

A number of studies have addressed the relations between climatic variables and milk composition, but these works used univariate statistical approaches. In our study, we used a multivariate approach (canonical correlation) to study the impact of climatic variables on milk composition, price, and monthly milk production at a dairy farm using bulk tank milk data. Data on milk composition, price, and monthly milk production were obtained from a dairy company that purchased the milk from the farm, while climatic variable data were obtained from the National Institute of Meteorology (INMET). The data are from January 2014 to December 2016. Univariate correlation analysis and canonical correlation analysis were performed. Few correlations between the climatic variables and milk composition were found using a univariate approach. However, using canonical correlation analysis, we found a strong and significant correlation (r c  = 0.95, p value = 0.0029). Lactose, ambient temperature measures (mean, minimum, and maximum), and temperature-humidity index (THI) were found to be the most important variables for the canonical correlation. Our study indicated that 10.2% of the variation in milk composition, pricing, and monthly milk production can be explained by climatic variables. Ambient temperature variables, together with THI, seem to have the most influence on variation in milk composition.

Relationship between climatic variables and the variation in bulk tank milk composition using canonical correlation analysis

NASA Astrophysics Data System (ADS)

Stürmer, Morgana; Busanello, Marcos; Velho, João Pedro; Heck, Vanessa Isabel; Haygert-Velho, Ione Maria Pereira

2018-06-01

A number of studies have addressed the relations between climatic variables and milk composition, but these works used univariate statistical approaches. In our study, we used a multivariate approach (canonical correlation) to study the impact of climatic variables on milk composition, price, and monthly milk production at a dairy farm using bulk tank milk data. Data on milk composition, price, and monthly milk production were obtained from a dairy company that purchased the milk from the farm, while climatic variable data were obtained from the National Institute of Meteorology (INMET). The data are from January 2014 to December 2016. Univariate correlation analysis and canonical correlation analysis were performed. Few correlations between the climatic variables and milk composition were found using a univariate approach. However, using canonical correlation analysis, we found a strong and significant correlation (r c = 0.95, p value = 0.0029). Lactose, ambient temperature measures (mean, minimum, and maximum), and temperature-humidity index (THI) were found to be the most important variables for the canonical correlation. Our study indicated that 10.2% of the variation in milk composition, pricing, and monthly milk production can be explained by climatic variables. Ambient temperature variables, together with THI, seem to have the most influence on variation in milk composition.

Compositional variation in the chevkinite group: New data from igneous and metamorphic rocks

USGS Publications Warehouse

Macdonald, R.; Belkin, H.E.; Wall, F.; Baginski, B.

2009-01-01

Electron microprobe analyses are presented of chevkinite-group minerals from Canada, USA, Guatemala, Norway, Scotland, Italy and India. The host rocks are metacarbonates, alkaline and subalkaline granitoids, quartz-bearing pegmatites, carbonatite and an inferred K-rich tuff. The analyses extend slightly the range of compositions in the chevkinite group, e.g. the most MgO-rich phases yet recorded, and we report two further examples where La is the dominant cation in the A site. Patchilyzoned crystals from Virginia and Guatemala contain both perrierite and chevkinite compositions. The new and published analyses are used to review compositional variation in minerals of the perrierite subgroup, which can form in a wide range of host rock compositions and over a substantial pressure-temperature range. The dominant substitutions in the various cation sites and a generalized substitution scheme are described. ?? 2009 The Mineralogical Society.

Compositional variation in the chevkinite group: new data from igneous and metamorphic rocks

USGS Publications Warehouse

Belkin, Harvey E.; MacDonald, R.; Wall, F.; Baginski, B.

2009-01-01

Electron microprobe analyses are presented of chevkinite-group minerals from Canada, USA, Guatemala, Norway, Scotland, Italy and India. The host rocks are metacarbonates, alkaline and subalkaline granitoids, quartz-bearing pegmatites, carbonatite and an inferred K-rich tuff. The analyses extend slightly the range of compositions in the chevkinite group, e.g. the most MgO-rich phases yet recorded, and we report two further examples where La is the dominant cation in the A site. Patchily- zoned crystals from Virginia and Guatemala contain both perrierite and chevkinite compositions. The new and published analyses are used to review compositional variation in minerals of the perrierite subgroup, which can form in a wide range of host rock compositions and over a substantial pressure- temperature range. The dominant substitutions in the various cation sites and a generalized substitution scheme are described.

Intraspecific variation in egg size and egg composition in birds: effects on offspring fitness.

PubMed

Williams, T D

1994-02-01

1. There is little unequivocal evidence to date in support of a positive relationship between egg size and offspring fitness in birds. Although 40 studies (of 34 species) have considered the effect of variation in egg size on chick growth and/or survival up to fledgling only 12 studies have controlled for other characters potentially correlated both with egg size and offspring fitness. Of these only two have reported a significant residual effect of egg size on chick growth (in the roseate tern and European blackbird) and three a residual effect on chick survival (all in seabirds: common tern, lesser black-backed gull and kittiwake). 2. More consistent evidence exists, though from fewer studies, for a positive relationship between egg size and offspring fitness early in the chick-rearing period; chick growth and chick survival being dependent on egg size in 8 of 10 studies and 4 of 5 studies respectively. It is suggested that the most important effect of variation in egg size might be in determining the probability of offspring survival in the first few days after hatching. 3. Egg size explains on average 66% of the variation in chick mass at hatching (n = 35 studies) but only 30% of the variation in chick body size (n = 18). When effects of hatching body size are controlled for chick mass remains significantly correlated with egg size, though the reverse is not true. This supports the hypothesis that large eggs give rise to heavier chicks at hatching, i.e., chicks with more nutrient (yolk) reserves, rather than structurally larger chicks. 4. Egg composition increased isometrically with increasing egg size in about half the studies so far reported (n equals approximately 20). However, in seabirds, and some passerines, larger eggs contain disproportionately more albumen, whilst in some waterfowl percentage yolk content increases with increasing egg size. Changes in albumen content largely reflect variation in the water content of eggs, but changes in yolk content

CCE plasma wave observations during the storm of September 4, 5, 1984. [Charge Composition Explorer

NASA Technical Reports Server (NTRS)

Scarf, F. L.

1985-01-01

Near 0700 on September 4, 1984 a series of interplanetary discontinuities arrived at earth when the AMPTE Charge Composition Explorer (CCE) was near apogee. During the next few hours the spacecraft passed in and out of the magnetosheath. At the magnetopause boundary, the CCE wave instrument detected strong electron plasma oscillations, weaker electromagnetic waves at the electron plasma frequency, and broadband electrostatic waves. During the subsequent perigee passes on September 4 and 5, the wave observations of upper hybrid resonance emissions, continuum radiation, electrostatic noise bands and unusual low latitude auroral kilometic radiation were used to monitor significant variations in the magnetospheric characteristics as the main storm phases developed.

Seasonal variations in dissolved neodymium isotope composition in the Bay of Bengal

NASA Astrophysics Data System (ADS)

Yu, Zhaojie; Colin, Christophe; Meynadier, Laure; Douville, Eric; Dapoigny, Arnaud; Reverdin, Gilles; Wu, Qiong; Wan, Shiming; Song, Lina; Xu, Zhaokai; Bassinot, Frank

2017-12-01

Constraining the dissolved neodymium (Nd) cycle in the ocean is paramount for using Nd isotopic composition (εNd) as a tracer to reconstruct deep-sea paleocirculations or continental weathering on different time scales. Dissolved εNd has been measured in seawater samples from six hydrological stations collected along ∼89°E North-South transect in the Bay of Bengal (BoB) in order to assess the impact of seasonal freshwater and sediment discharges from the continental river systems. Seawater samples collected in this study during June 2012 reveal more radiogenic εNd (a difference of ∼2 Epsilon units for the upper 2000 m, and ∼0.5 Epsilon unit below 2000 m) and ∼3-8 pmol/kg lower Nd concentrations than the reported values of nearby seawater samples collected in November 2008. These observations are most plausibly explained by a seasonal variations in dissolved Nd concentrations and εNd in the BoB, induced by seasonal variations in the freshwater and sediment discharges from the Ganges-Brahmaputra (G-B) river system. However, we cannot entirely exclude the possibility of spatial differences given that the water stations collected in this study are not exactly the same positions collected in November 2008. A two-box model suggests, (1) the particulate Nd inputs from the G-B river system mainly control the seasonal shift of εNd observed in the BoB seawater, and (2) a very rapid Nd exchange exists between lithogenic particles and seawater (at least on the scale of a few months). Seasonal changes in seawater εNd may also occur in other marginal seas and in the outflows of major rivers, and these need to be taken into account when using the εNd proxy in the ocean.

Spectral variations of LMC X-3 observed with Ginga

NASA Technical Reports Server (NTRS)

Ebisawa, Ken; Makino, Fumiyoshi; Mitsuda, Kazuhisa; Belloni, Tomaso; Cowley, Anne P.; Schmidtke, Paul C.; Treves, Aldo

1993-01-01

The prime black hole candidate LMC X-3 was observed over three years with the Ginga satellite, and a characteristic spectral variation was found accompanying the periodic intensity variation of about 198 (or possibly about 99) days (Cowley et al., 1991). The energy spectrum of LMC X-3 consists of the soft, thermal component and the hard, power-law component, which are respectively dominant below and above about 9 keV. The soft component, which carries most of the X-ray intensity, shows a clear correlation between the intensity and the hardness, while the hard component varies independently of the soft component. It was found that the spectral variation of the soft component is well described by an optically thick accretion disk model with a remarkably constant innermost radius and variable mass accretion rate. The constancy of the innermost radius suggests it is related to the mass of the central object.

Localized Temperature Variations in Laser-Irradiated Composites with Embedded Fiber Bragg Grating Sensors.

PubMed

Jenkins, R Brian; Joyce, Peter; Mechtel, Deborah

2017-01-27

Fiber Bragg grating (FBG) temperature sensors are embedded in composites to detect localized temperature gradients resulting from high energy infrared laser radiation. The goal is to detect the presence of radiation on a composite structure as rapidly as possible and to identify its location, much the same way human skin senses heat. A secondary goal is to determine how a network of sensors can be optimized to detect thermal damage in laser-irradiated composite materials or structures. Initial tests are conducted on polymer matrix composites reinforced with either carbon or glass fiber with a single optical fiber embedded into each specimen. As many as three sensors in each optical fiber measure the temporal and spatial thermal response of the composite to high energy radiation incident on the surface. Additional tests use a 2 × 2 × 3 array of 12 sensors embedded in a carbon fiber/epoxy composite to simultaneously measure temperature variations at locations on the composite surface and through the thickness. Results indicate that FBGs can be used to rapidly detect temperature gradients in a composite and their location, even for a direct strike of laser radiation on a sensor, when high temperatures can cause a non-uniform thermal response and FBG decay.

Localized Temperature Variations in Laser-Irradiated Composites with Embedded Fiber Bragg Grating Sensors

PubMed Central

Jenkins, R. Brian; Joyce, Peter; Mechtel, Deborah

2017-01-01

Fiber Bragg grating (FBG) temperature sensors are embedded in composites to detect localized temperature gradients resulting from high energy infrared laser radiation. The goal is to detect the presence of radiation on a composite structure as rapidly as possible and to identify its location, much the same way human skin senses heat. A secondary goal is to determine how a network of sensors can be optimized to detect thermal damage in laser-irradiated composite materials or structures. Initial tests are conducted on polymer matrix composites reinforced with either carbon or glass fiber with a single optical fiber embedded into each specimen. As many as three sensors in each optical fiber measure the temporal and spatial thermal response of the composite to high energy radiation incident on the surface. Additional tests use a 2 × 2 × 3 array of 12 sensors embedded in a carbon fiber/epoxy composite to simultaneously measure temperature variations at locations on the composite surface and through the thickness. Results indicate that FBGs can be used to rapidly detect temperature gradients in a composite and their location, even for a direct strike of laser radiation on a sensor, when high temperatures can cause a non-uniform thermal response and FBG decay. PMID:28134815

Impact-induced compositional variations on Mercury

NASA Astrophysics Data System (ADS)

Rivera-Valentin, E. G.; Barr, A. C.

2013-12-01

The surface of Mercury shows unexpected spectral variations spatially associated with crater and basin ejecta (the so-called 'low-reflectance material' or LRM; [1]). The low reflectance is suggested to be caused by a native darkening agent at depth that has been excavated and redeposited onto the surface [1]. Although LRM is generally associated with crater ejecta, it is not found within the ejecta blankets of many large impact craters, perhaps suggesting that the subsurface source is heterogeneous [2]. We have developed a 3-D Monte Carlo model of impact cratering, excavation, and ejecta blanket deposition. Our simulations of the effect of early impacts onto Mercury show that if the LRM originates from depth to cover ~15% of Mercury's surface [2], its source is ~30 km deep. Considering the estimated mercurian crustal thickness of 50 km [3] this implies the darkening agent is most probably located within a chemically distinct lower crust. Simulations show that repeated and overlapping impacts redistribute the darkening agent away from the basin source and create a weak association between crater size and LRM abundance. Thus subsurface heterogeneity is not required to produce the weak association between crater size and LRM abundance within crater ejecta; this is a natural consequence of overlapping impacts. Our results can elucidate the new high-resolution compositional mapping of Mercury's heavily cratered terrain and provide insight into subsurface composition. Acknowledgements: This work is supported by the Center for Lunar Origin and Evolution through the NASA Lunar Science Institute NNA09DB32A. References: [1] Denevi and Robinson, 2008, Icarus 197, 239-246. [2] Denevi et al., 2009, Science 324, 613-618. [3] Smith et al., 2012, Science 336, 214-217.

Ethnic variation in melanin content and composition in photoexposed and photoprotected human skin.

PubMed

Alaluf, Simon; Atkins, Derek; Barrett, Karen; Blount, Margaret; Carter, Nik; Heath, Alan

2002-04-01

We have examined the quantity and composition of melanin in both photoprotected (volar upper arm) and chronically photoexposed (dorsal forearm) skin from a range of different ethnic skin types including African, Indian, Mexican, Chinese and European. The most lightly pigmented (European, Chinese and Mexican) skin types have approximately half as much epidermal melanin as the most darkly pigmented (African and Indian) skin types. However, the composition of melanin in these lighter skin types is comparatively more enriched with lightly coloured, alkali-soluble melanin components (up to three-fold). Regardless of ethnicity, epidermal melanin content is significantly greater in chronically photoexposed skin than it is in corresponding photoprotected skin (up to two-fold). However, by comparison there is only a modest enrichment of lightly coloured, alkali soluble melanin components in photoprotected skin (up to 1.3-fold). Analysis of melanosomes extracted from the epidermis in these subjects indicates that the proportion of spheroidal melanosomes is low in all skin types examined (<10%). This suggests that in human skin, pheomelanin is a very minor component of epidermal melanin, even in the lightest (European) skin types. Analysis of melanosome size revealed a significant and progressive variation in size with ethnicity: African skin having the largest melanosomes followed in turn by Indian, Mexican, Chinese and European. On the basis of these findings, we propose that variation in skin pigmentation is strongly influenced by both the amount and the composition (or colour) of the melanin in the epidermis. Variation in melanosome size may also play a significant role. However, the data also suggest that in human skin there are subtle differences in the mechanisms associated with the maintenance of constitutive pigmentation and facultative hyperpigmentation, respectively.

A regional study of the seasonal variation in the molecular composition of rainwater

NASA Astrophysics Data System (ADS)

Cottrell, Barbara A.; Gonsior, Michael; Isabelle, Lorne M.; Luo, W.; Perraud, Véronique; McIntire, Theresa M.; Pankow, James F.; Schmitt-Kopplin, Philippe; Cooper, William J.; Simpson, André J.

2013-10-01

Rainwater is not only a critical source of drinking and agricultural water but it plays a key role in the fate and transport of contaminants through their removal by wet deposition. Rainwater is a complex mixture of organic compounds yet despite its importance its spatial and temporal variability are not well understood and less than 50% of the organic matter has been characterized. In-depth analytical approaches were used in this study to characterize the seasonal variation in rainwater composition. Rainwater samples were collected over a one-year period in Scarborough, Ontario, Canada. The seasonal variation of atmospheric organic carbon (AOC) in rainwater was analyzed by excitation-emission matrix spectroscopy (EEMs), 1D and 2D NMR with compound identification by spectral database matching, GC-MS, FT-ICR-MS, and GC × GC-TOFMS. This combination of techniques provided four complementary datasets, with less than 10% overlap, of anthropogenic and biogenic AOC. NMR with database matching identified over 100 compounds, primarily carboxylic acids, carbohydrates, and nitrogen-containing compounds. GC × GC-TOFMS analysis identified 344 compounds in two rain events with 33% of the compounds common to both events. FT-ICR-MS generated a seasonally dependent profile of 1226-1575 molecular ions of CHO, CHOS, and CHON elemental composition. FT-ICR-MS and GC × GC-TOFMS datasets were compared using van Krevelen diagrams (H/C vs. O/C), the H/C ratio vs. mass/charge (m/z), and the carbon oxidation state/carbon number matrix. Fluorescence patterns were correlated with NMR results resulting in the identification one seasonally-dependent component of chromophoric dissolved organic matter (CDOM). This study demonstrated the importance of using of an integrated analytical approach to monitor the compositional variation of AOC.

Variational finite-difference methods in linear and nonlinear problems of the deformation of metallic and composite shells (review)

NASA Astrophysics Data System (ADS)

Maksimyuk, V. A.; Storozhuk, E. A.; Chernyshenko, I. S.

2012-11-01

Variational finite-difference methods of solving linear and nonlinear problems for thin and nonthin shells (plates) made of homogeneous isotropic (metallic) and orthotropic (composite) materials are analyzed and their classification principles and structure are discussed. Scalar and vector variational finite-difference methods that implement the Kirchhoff-Love hypotheses analytically or algorithmically using Lagrange multipliers are outlined. The Timoshenko hypotheses are implemented in a traditional way, i.e., analytically. The stress-strain state of metallic and composite shells of complex geometry is analyzed numerically. The numerical results are presented in the form of graphs and tables and used to assess the efficiency of using the variational finite-difference methods to solve linear and nonlinear problems of the statics of shells (plates)

Longitudinal Changes and Seasonal Variation in Body Composition in Professional Australian Football Players.

PubMed

Bilsborough, Johann C; Kempton, Thomas; Greenway, Kate; Cordy, Justin; Coutts, Aaron J

2017-01-01

To compare development and variations in body composition of early-, mid-, and late-career professional Australian Football (AF) players over 3 successive seasons. Regional and total-body composition (body mass [BM], fat mass [FM], fat-free soft-tissue mass [FFSTM], and bone mineral content [BMC]) were assessed 4 times, at the same time of each season-start preseason (SP), end preseason (EP), midseason (MS), and end season (ES)-from 22 professional AF players using pencil-beam dual-energy X-ray absorptiometry. Nutritional intake for each player was evaluated concomitantly using 3-d food diaries. Players were classified according to their age at the beginning of the observational period as either early- (<21 y, n = 8), mid- (21 to 25 y, n = 9), or late- (>25 y, n = 5) career athletes. Early-career players had lower FFSTM, BMC, and BM than mid- and late-career throughout. FM and %FM had greatest variability, particularly in the early-career players. FM reduced and FFSTM increased from SP to EP, while FM and FFSTM decreased from EP to MS. FM increased and FFSTM decreased from MS to ES, while FM and FFSTM increased during the off-season. Early-career players may benefit from greater emphasis on specific nutrition and resistance-training strategies aimed at increasing FFSTM, while all players should balance training and diet toward the end of season to minimize increases in FM.

Energy-dependent intensity variation of the persistent X-ray emission of magnetars observed with Suzaku

NASA Astrophysics Data System (ADS)

Nakagawa, Yujin; Ebisawa, Ken; Enoto, Teruaki

2018-03-01

The emission mechanism of magnetars is still controversial even though various observational and theoretical studies have been made. In order to investigate mechanisms of both the persistent X-ray emission and the burst emission of the magnetars, we propose a model in which the persistent X-ray emission consists of numerous micro-bursts of various sizes. If this model is correct, root mean square (rms) intensity variations of the persistent emission would exceed the values expected from the Poisson distribution. Using Suzaku archive data of 11 magnetars (22 observations), the rms intensity variations were calculated from 0.2 keV to 70 keV. As a result, we found significant excess rms intensity variations from all 11 magnetars. We suppose that numerous micro-bursts constituting the persistent X-ray emission cause the observed variations, suggesting that the persistent X-ray emission and the burst emission have identical emission mechanisms. In addition, we found that the rms intensity variations clearly increase toward higher energy bands for four magnetars (six observations). The energy-dependent rms intensity variations imply that the soft thermal component and the hard X-ray component are emitted from different regions far apart from each other.

Reservoirs for Comets: Compositional Differences Based on Infrared Observations

NASA Astrophysics Data System (ADS)

Disanti, Michael A.; Mumma, Michael J.

Tracing measured compositions of comets to their origins continues to be of keen interest to cometary scientists and to dynamical modelers of Solar System formation and evolution. This requires building a taxonomy of comets from both present-day dynamical reservoirs: the Kuiper Belt (hereafter KB), sampled through observation of ecliptic comets (primarily Jupiter Family comets, or JFCs), and the Oort cloud (OC), represented observationally by the long-period comets and by Halley Family comets (HFCs). Because of their short orbital periods, JFCs are subjected to more frequent exposure to solar radiation compared with OC comets. The recent apparitions of the JFCs 9P/Tempel 1 and 73P/Schwassmann-Wachmann 3 permitted detailed observations of material issuing from below their surfaces—these comets added significantly to the compositional database on this dynamical class, which is under-represented in studies of cometary parent volatiles. This chapter reviews the latest techniques developed for analysis of high-resolution spectral observations from ˜2-5 μm, and compares measured abundances of native ices among comets. While no clear compositional delineation can be drawn along dynamical lines, interesting comparisons can be made. The sub-surface composition of comet 9P, as revealed by the Deep Impact ejecta, was similar to the majority of OC comets studied. Meanwhile, 73P was depleted in all native ices except HCN, similar to the disintegrated OC comet C/1999 S4 (LINEAR). These results suggest that 73P may have formed in the inner giant planets' region while 9P formed farther out or, alternatively, that both JFCs formed farther from the Sun but with 73P forming later in time.

Reservoirs for Comets: Compositional Differences Based on Infrared Observations

NASA Astrophysics Data System (ADS)

Disanti, Michael A.; Mumma, Michael J.

2008-07-01

Tracing measured compositions of comets to their origins continues to be of keen interest to cometary scientists and to dynamical modelers of Solar System formation and evolution. This requires building a taxonomy of comets from both present-day dynamical reservoirs: the Kuiper Belt (hereafter KB), sampled through observation of ecliptic comets (primarily Jupiter Family comets, or JFCs), and the Oort cloud (OC), represented observationally by the long-period comets and by Halley Family comets (HFCs). Because of their short orbital periods, JFCs are subjected to more frequent exposure to solar radiation compared with OC comets. The recent apparitions of the JFCs 9P/Tempel 1 and 73P/Schwassmann-Wachmann 3 permitted detailed observations of material issuing from below their surfaces—these comets added significantly to the compositional database on this dynamical class, which is under-represented in studies of cometary parent volatiles. This chapter reviews the latest techniques developed for analysis of high-resolution spectral observations from ˜2 5 μm, and compares measured abundances of native ices among comets. While no clear compositional delineation can be drawn along dynamical lines, interesting comparisons can be made. The sub-surface composition of comet 9P, as revealed by the Deep Impact ejecta, was similar to the majority of OC comets studied. Meanwhile, 73P was depleted in all native ices except HCN, similar to the disintegrated OC comet C/1999 S4 (LINEAR). These results suggest that 73P may have formed in the inner giant planets’ region while 9P formed farther out or, alternatively, that both JFCs formed farther from the Sun but with 73P forming later in time.

Inter-specific variation in headspace scent volatiles composition of four commercially cultivated jasmine flowers.

PubMed

Bera, Paramita; Kotamreddy, Jhansi Narmada Reddy; Samanta, Tanmoy; Maiti, Saborni; Mitra, Adinpunya

2015-01-01

Jasmines are commercially grown for their fragrant flowers and essential oil production. The flowers of jasmine emit sweet-smelling fragrance from evening till midnight. This study was designed to study the composition and inter-specific variation of the emitted scent volatiles from flowers of four commercially cultivated Jasminum species namely, Jasminum sambac, Jasminum auriculatum, Jasminum grandiflorum and Jasminum multiflorum. Gas chromatography-mass spectrometry analysis revealed that the scent volatiles composition of these flowers was predominantly enriched with both terpenoid and benzenoid compounds. Linalool and (3E,6E)-α-farnesene were identified as the major monoterpene and sesquiterpene in all the four species, respectively. The most abundant benzenoid detected in all flowers was benzyl acetate. Comparison of volatile profiles indicated a variation in fragrance contents and types emitted from these four jasmine flowers. The outcome of this study shall help in elucidating the enzymes and genes of fragrance biosynthesis in jasmines and in aiming to create flowers with improved scent quality.

A Search for Variation in the Surface Mineralogical Composition of J VI Himalia

NASA Astrophysics Data System (ADS)

Jarvis, K. S.; Vilas, F.; Larson, S. M.; Gaffey, M. J.

1996-09-01

Diverse spectral data exist for Jupiter's moon J VI Himalia. The overall spectral shape suggests that it has the same mineralogical composition as a C-class asteroid, lending credibility to the theory that Himalia was a C-class asteroid that formed in or near the main asteroid belt and was ejected and captured into orbit around Jupiter. Using an algorithm developed earlier, ECAS photometry (Tholen and Zellner, 1984) of Himalia taken on one date only have tested positively for the presence of a 0.7- mu m feature attributed to an Fe(2+) -> Fe(3+) charge transfer transition in oxidized iron in phyllosilicates. The presence of this feature was confirmed by narrowband spectrophotometry obtained on one date in April, 1995. Narrowband spectrophotometry of Luu (1991) does not cover the full spectral range defined by the 0.7-mu m absorption feature, but is in good agreement with the ECAS photometry. However, no 3.0-mu m water of hydration absorption feature was observed in IR radiometry (A. S., Rivkin, per. comm.). Correlation between the 0.7-mu m feature and the 3.0-mu m feature has been demonstrated in spectra of low-albedo asteroids, and suggests that it should be present. A rough rotational period for Himalia of 9.2 - 9.8 hrs is known. Himalia could represent the junction of two different compositional units, produced when an impact fragmented Himalia's parent body. The presence of iron-bearing phyllosilicates on part of Himalia's surface supports the hypothesis that Himalia is a captured C-class asteroid. Rotationally-resolved spectra of Himalia could confirm a variation in composition; we have started a program to collect these data.

Observations of Co-variation in Cloud Properties and their Relationships with Atmospheric State

NASA Astrophysics Data System (ADS)

Sinclair, K.; van Diedenhoven, B.; Fridlind, A. M.; Arnold, T. G.; Yorks, J. E.; Heymsfield, G. M.; McFarquhar, G. M.; Um, J.

2017-12-01

Radiative properties of upper tropospheric ice clouds are generally not well represented in global and cloud models. Cloud top height, cloud thermodynamic phase, cloud optical thickness, cloud water path, particle size and ice crystal shape all serve as observational targets for models to constrain cloud properties. Trends or biases in these cloud properties could have profound effects on the climate since they affect cloud radiative properties. Better understanding of co-variation between these cloud properties and linkages with atmospheric state variables can lead to better representation of clouds in models by reducing biases in their micro- and macro-physical properties as well as their radiative properties. This will also enhance our general understanding of cloud processes. In this analysis we look at remote sensing, in situ and reanalysis data from the MODIS Airborne Simulator (MAS), Cloud Physics Lidar (CPL), Cloud Radar System (CRS), GEOS-5 reanalysis data and GOES imagery obtained during the Tropical Composition, Cloud and Climate Coupling (TC4) airborne campaign. The MAS, CPL and CRS were mounted on the ER-2 high-altitude aircraft during this campaign. In situ observations of ice size and shape were made aboard the DC8 and WB57 aircrafts. We explore how thermodynamic phase, ice effective radius, particle shape and radar reflectivity vary with altitude and also investigate how these observed cloud properties vary with cloud type, cloud top temperature, relative humidity and wind profiles. Observed systematic relationships are supported by physical interpretations of cloud processes and any unexpected differences are examined.

Variations of Solar Radius Observed with RHESSI

NASA Astrophysics Data System (ADS)

Fivian, M. D.; Hudson, H. S.; Lin, R. P.

2003-12-01

The Solar Aspect System (SAS) of the rotating (at 15 rpm) RHESSI spacecraft has three subsystems. Each of these measures the position of the limb by sampling the full solar chord profile with a linear CCD using a narrow bandwidth filter at 670 nm. With a resolution of each CCD of 1.7 arcsec/pixel, the accuracy of each of the 6 limb positions is theoretically better than 50 mas using 4 pixels at each limb. Since the launch of RHESSI early 2002, solar limbs are sampled with at least 100 Hz. That provides a database of currently 4 x 109 single radius measurements. The main function of SAS is to determine the RHESSI pointing relative to Sun center. The observed precision of this determination has a typical instantaneous (16 Hz) value of about 200 mas (rms). We show and discuss first results of variations of solar radius observed with RHESSI.

Variations in the milk yield and milk composition of dairy cows during lactation.

PubMed

Bedö, S; Nikodémusz, E; Percsich, K; Bárdos, L

1995-01-01

Variations in the milk yield and milk composition of a dairy cow colony (n = 23) were analyzed during 11 months of lactation. Milk yield followed a characteristic decreasing pattern in negative correlations with solid components (milk protein, lactose, total solids, milk fat). Titrable acidity (degree SH) was significantly (p < 0.1) higher in the milk of fresh-milking cows and it correlated negatively with lactose and positively with milk protein, milk fat and total solids. The concentrations of Zn, Fe and Cu tended to decrease, while Mn showed insignificant variation during lactation. Milk vitamin A showed a significant positive whilst milk vitamin E had a negative correlation with milk fat.

Compositional Variation in Large-Diameter Low-Albedo asteroids

NASA Astrophysics Data System (ADS)

Vilas, F.; Jarvis, K. S.; Thibault, C. A.; Sawyer, S. R.

2000-12-01

Age dating of meteorites indicates that the Solar System was subjected to a major heating event 4.5 Gyr ago. Models of the effects of heating by electromagnetic induction or decay of short-lived radionuclides combined with models of the early collisional history of the Solar System after Jupiter's formation indicate that asteroids observed today can be divided into two groups by diameter. Those asteroids having diameters greater than 100 km were mixed by multiple collisions but remain as gravitationally bound rubble piles. Asteroids with diameters less than 100 km should show more compositional diversity. Vilas and Sykes (1996, Icarus, 124) have shown using ECAS photometry that this compositional difference exists. The larger diameter group should be individually homogenous, with spectral differences showing the combined effects of a primordial compositional gradient in the asteroid belt with thermal metamorphism. We address the significance of 36 rotationally-resolved spectra of larger-diameter low-albedo asteroids of the C class (and subclasses B, F, G) and P class in the visible and Near-IR spectral regions. This work was supported by the NASA Planetary Astronomy program.

Atmospheric diurnal and semi-diurnal variations observed with GPS radio occultation soundings

NASA Astrophysics Data System (ADS)

Xie, F.; Wu, D. L.; Ao, C. O.; Mannucci, A. J.

2009-11-01

Diurnal and semi-diurnal variations, driven by solar forcing, are two fundamental modes in the Earth's weather and climate system. Radio occultation (RO) measurements from the six COSMIC satellites (Constellation Observing System for Meteorology Ionosphere and Climate) provide rather uniform global coverage with high vertical resolution, all-weather and diurnal sampling capability. This paper analyzes the diurnal and semi-diurnal variations of both temperature and refractivity from two-year (2007-2008) COSMIC RO measurements in the troposphere and stratosphere. The RO observations reveal both propagating and trapped vertical structures of diurnal and semi-diurnal variations, including transition regions near the tropopause where data with high vertical resolution are critical. In the tropics the diurnal amplitude in refractivity decreases with altitude from a local maximum in the planetary boundary layer and reaches the minimum around 14 km and then further increase amplitude in the stratosphere. The upward propagating component of the migrating diurnal tides in the tropics is clearly captured by the GPS RO measurements, which show a downward progression in phase from upper troposphere to the stratopause with a vertical wavelength of about 25 km. Below 500 hPa (~5.5 km), seasonal variations of the peak diurnal amplitude in the tropics follow the solor forcing change in latitude, while at 30 km the seasonal pattern reverses with the diurnal amplitude peaking at the opposite side of the equator relative to the solar forcing. Polar regions shows large diurnal variations in the stratosphere with strong seasonal variations and the cause(s) of these variations require further investigations.

Chemical variations observed on Aeolis Mons in Gale Crater, Mars

NASA Astrophysics Data System (ADS)

Frydenvang, Jens; Gasda, Patrick J.; Thompson, Lucy; Hurowitz, Joel; Grotzinger, John P.; Blaney, Diana L.; Gellert, Ralf; Wiens, Roger; Vasavada, Ashwin R.; MSL Science Team

2016-10-01

The extraordinarily extensive exposure of hematite-, clay-, sulfate-bearing stratigraphic layers in the lower part of Aeolis Mons was the primary reason Gale Crater was selected as the landing site for the Mars Science Laboratory rover, Curiosity. 753 martian solar days (sols) after the Curiosity rover landed in Gale Crater in August 2012, and after driving more than 9 km, the Curiosity rover arrived at the first exposure of the Murray formation, the basal layer of Aeolis Mons. The Murray formation is a thinly laminated lacustrine mudstone showing stratification down to the millimeter scale. This supports the idea that the stratigraphic layers of Aeolis Mons are sedimentary, and likely deposited in a series of long-lived lakes extending into the early Hesperian time, as recently described by Grotzinger et al. (Science, vol. 350, 2015). The chemical variations observed throughout the Murray formation by the ChemCam and APXS instruments in the 600+ sols since first arriving at Aeolis Mons will be presented. While Murray remains thinly laminated throughout the 30+ vertical meters of stratigraphy explored, large chemical variations are observed. The most extreme variations arise from likely co-located detrital and diagenetic silica enrichments in Murray. Remarkably, an associated diagenetic silica enrichment is also observed in the unconformably overlying eolian sandstone of the Stimson formation in that location. The detrital enrichment provides evidence of how the source region chemistry varied as the sedimentary layers of Aeolis Mons were deposited. Conversely, the diagenetic enrichment observed across both the Murray and Stimson formations provides compelling evidence for the presence of subsurface fluids in Gale Crater, thousands to millions of years after the crater lakes disappeared. This evidence of liquid water greatly extends the timescale in which Gale Crater might have been habitable.

Differences in glycosyltransferase family 61 accompany variation in seed coat mucilage composition in Plantago spp.

PubMed

Phan, Jana L; Tucker, Matthew R; Khor, Shi Fang; Shirley, Neil; Lahnstein, Jelle; Beahan, Cherie; Bacic, Antony; Burton, Rachel A

2016-12-01

Xylans are the most abundant non-cellulosic polysaccharide found in plant cell walls. A diverse range of xylan structures influence tissue function during growth and development. Despite the abundance of xylans in nature, details of the genes and biochemical pathways controlling their biosynthesis are lacking. In this study we have utilized natural variation within the Plantago genus to examine variation in heteroxylan composition and structure in seed coat mucilage. Compositional assays were combined with analysis of the glycosyltransferase family 61 (GT61) family during seed coat development, with the aim of identifying GT61 sequences participating in xylan backbone substitution. The results reveal natural variation in heteroxylan content and structure, particularly in P. ovata and P. cunninghamii, species which show a similar amount of heteroxylan but different backbone substitution profiles. Analysis of the GT61 family identified specific sequences co-expressed with IRREGULAR XYLEM 10 genes, which encode putative xylan synthases, revealing a close temporal association between xylan synthesis and substitution. Moreover, in P. ovata, several abundant GT61 sequences appear to lack orthologues in P. cunninghamii. Our results indicate that natural variation in Plantago species can be exploited to reveal novel details of seed coat development and polysaccharide biosynthetic pathways. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Long-term tropospheric and lower stratospheric ozone variations from ozonesonde observations

NASA Technical Reports Server (NTRS)

London, J.; Liu, S. C.

1992-01-01

An analysis is presented of the long-term mean pressure-latitude seasonal distribution of tropospheric and lower stratospheric ozone for the four seasons covering, in part, over 20 years of ozonesonde data. The observed patterns show minimum ozone mixing ratios in the equatorial and tropical troposphere except in regions where net photochemical production is dominant. In the middle and upper troposphere, and low stratosphere to 50 mb, ozone increases from the tropics to subpolar latitudes of both hemispheres. In mid stratosphere, the ozone mixing ratio is a maximum over the tropics. The observed vertical ozone gradient is small in the troposphere but increases rapidly above the tropopause. The amplitude of the annual variation increases from a minimum in the tropics to a maximum in polar regions. Also, the amplitude increases with height at all latitudes up to about 30 mb where the phase of the annual variation changes abruptly. The phase of the annual variation is during spring in the boundary layer, summer in mid troposphere, and spring in the upper troposhere and lower stratosphere.

Simultaneous Observations of Atmospheric Tides from Combined in Situ and Remote Observations at Mars from the MAVEN Spacecraft

NASA Technical Reports Server (NTRS)

England, Scott L.; Liu, Guiping; Withers, Paul; Yigit, Erdal; Lo, Daniel; Jain, Sonal; Schneider, Nicholas M. (Inventor); Deighan, Justin; McClintock, William E.; Mahaffy, Paul R.;

High Frequency Variations in Earth Orientation Derived From GNSS Observations

NASA Astrophysics Data System (ADS)

Weber, R.; Englich, S.; Snajdrova, K.; Boehm, J.

2006-12-01

Current observations gained by the space geodetic techniques, especially VLBI, GPS and SLR, allow for the determination of Earth Orientation Parameters (EOPs - polar motion, UT1/LOD, nutation offsets) with unprecedented accuracy and temporal resolution. This presentation focuses on contributions to the EOP recovery provided by satellite navigation systems (primarily GPS). The IGS (International GNSS Service), for example, currently provides daily polar motion with an accuracy of less than 0.1mas and LOD estimates with an accuracy of a few microseconds. To study more rapid variations in polar motion and LOD we established in a first step a high resolution (hourly resolution) ERP-time series from GPS observation data of the IGS network covering the period from begin of 2005 till March 2006. The calculations were carried out by means of the Bernese GPS Software V5.0 considering observations from a subset of 79 fairly stable stations out of the IGb00 reference frame sites. From these ERP time series the amplitudes of the major diurnal and semidiurnal variations caused by ocean tides are estimated. After correcting the series for ocean tides the remaining geodetic observed excitation is compared with variations of atmospheric excitation (AAM). To study the sensitivity of the estimates with respect to the applied mapping function we applied both the widely used NMF (Niell Mapping Function) and the VMF1 (Vienna Mapping Function 1). In addition, based on computations covering two months in 2005, the potential improvement due to the use of additional GLONASS data will be discussed. Finally, satellite techniques are also able to provide nutation offset rates with respect to the most recent nutation model. Based on GPS observations from 2005 we established nutation rate time series and subsequently derived the amplitudes of several nutation waves with periods less than 30 days. The results are compared to VLBI estimates processed by means of the OCCAM 6.1 software.

Physical observations of comets: Their composition, origin and evolution

NASA Technical Reports Server (NTRS)

Cochran, Anita L.; Barker, Edwin S.; Cochran, William D.

1991-01-01

The composition, origins, and evolution of comets were studied. The composition was studied using spectroscopic observations of primarily brighter comets at moderate and high resolution for the distribution of certain gases in the coma. The origins was addressed through an imaging search for the Kuiper belt of comets. The evolution was addressed by searching for a link between comets and asteroids using an imaging approach to search for an OH coma.

Dielectric studies on PEG-LTMS based polymer composites

NASA Astrophysics Data System (ADS)

Patil, Ravikumar V.; Praveen, D.; Damle, R.

2018-02-01

PEG LTMS based polymer composites were prepared and studied for dielectric constant variation with frequency and temperature as a potential candidate with better dielectric properties. Solution cast technique is used for the preparation of polymer composite with five different compositions. Samples show variation in dielectric constant with frequency and temperature. Dielectric constant is large at low frequencies and higher temperatures. Samples with larger space charges have shown larger dielectric constant. The highest dielectric constant observed was about 29244 for PEG25LTMS sample at 100Hz and 312 K.

Diurnal and seasonal variations of gas emissions in the inner coma of comet 67P/Churyumov-Gerasimenko observed with OSIRIS/Rosetta

NASA Astrophysics Data System (ADS)

La Forgia, F.; Lazzarin, M.; Bodewits, D.; A'Hearn, M. F.; Bertini, I.; Penasa, L.; Naletto, G.; Cremonese, G.; Massironi, M.; Ferri, F.; Frattin, E.; Lucchetti, A.; Ferrari, S.; Barbieri, C.

2017-09-01

The gas filters of OSIRIS/Wide Angle Camera (WAC) on board Rosetta spacecraft allowed to study the gaseous emissions of the inner coma of comet 67P/Churyumov-Gerasimenko. OH, NH, CN, NH2 and OI gas species have been monitored between January and September 2015, i.e. from 2.47 AU pre-perihelion, to 1.37 AU post-perihelion, allowing the study of seasonal variations. Each gas sequence covers slightly more than one comet rotation period allowing also the study of diurnal changes. We measured the gas column density between 1 and 3 km from the nucleus limb in the sunward direction. Results will be presented on the gas diurnal light curves and on the long-term variations such as the dependence and correlation with time, heliocentric distance, range, phase angle and sub-solar point. Gas ratios are studied searching for evidence of any compositional change with time and orbital evolution. We searched for connections between particular "active zones" on the nucleus surface. This study will be helpful in connecting ground based observations of 67P with Rosetta in situ observations.

DGAT1 underlies large genetic variation in milk-fat composition of dairy cows.

PubMed

Schennink, A; Stoop, W M; Visker, M H P W; Heck, J M L; Bovenhuis, H; van der Poel, J J; van Valenberg, H J F; van Arendonk, J A M

2007-10-01

Dietary fat may play a role in the aetiology of many chronic diseases. Milk and milk-derived foods contribute substantially to dietary fat, but have a fat composition that is not optimal for human health. We measured the fat composition of milk samples in 1918 Dutch Holstein Friesian cows in their first lactation and estimated genetic parameters for fatty acids. Substantial genetic variation in milk-fat composition was found: heritabilities were high for short- and medium-chain fatty acids (C4:0-C16:0) and moderate for long-chain fatty acids (saturated and unsaturated C18). We genotyped 1762 cows for the DGAT1 K232A polymorphism, which is known to affect milk-fat percentage, to study the effect of the polymorphism on milk-fat composition. We found that the DGAT1 K232A polymorphism has a clear influence on milk-fat composition. The DGAT1 allele that encodes lysine (K) at position 232 (232K) is associated with more saturated fat; a larger fraction of C16:0; and smaller fractions of C14:0, unsaturated C18 and conjugated linoleic acid (P < 0.001). We conclude that selective breeding can make a significant contribution to change the fat composition of cow's milk.

Diurnal variation climatology of short-lived at atmospheric compositions (ClO, BrO, HO2 and HOCl) derived from SMILES NICT data

NASA Astrophysics Data System (ADS)

Kreyling, Daniel; Sagawa, Hideo; Kasai, Yasuko

2013-04-01

We present a diurnal variation climatology for short-lived at atmospheric compositions, such as ClO, BrO, HO2 and HOCl, as well as for longer life time species, like O3 and HCl from observations of unprecedented sensitivity with the Superconducting SubMIllimeter wave Limb-Emission Sounder (SMILES), which is installed on the Japanese Experiment Module (JEM) at the International Space Station (ISS). With its non sun synchronous orbit, SMILES measurements comprise observations at all local times. The target altitude range is between lower stratosphere and mesopause. Differences in diurnal variation chemistry of strato-, and mesospheric BrO and ClO of the diurnal climatology are presented. The data employed is produced by the SMILES level 2 retrieval algorithm version 2.1.5 at the National Institute of Information and Communications Technology (NICT). The SMILES climatology data sets are available via the SMILES data distribution homepage in NICT at https://smiles-p6.nict.go.jp/products/research_latitude-longitude.jsf

Carbon Monoxide Data Assimilation for Atmospheric Composition and Climate Science: Evaluating Performance with Current and Future Observations

NASA Astrophysics Data System (ADS)

Barre, J.; Edwards, D. P.; Gaubert, B.; Worden, H. M.; Arellano, A. F.; Anderson, J. L.

2015-12-01

Current satellite observations of tropospheric composition made from low Earth orbit provide at best one or two measurements each day at any given location. Comparisons of Terra/MOPITT carbon monoxide (CO) and IASI/Metop CO observation assimilations will be presented. We use the DART Ensemble Adjustment Kalman Filter to assimilate observations in the CAM-Chem global chemistry-climate model. Data assimilation impacts due to both different instrument capabilities (i.e. vertical sensitivity and global coverage) will be discussed. Coverage is global but sparse, often with large uncertainties in individual measurements that limit examination of local and regional atmospheric composition over short time periods. This has hindered the operational uptake of these data for monitoring air quality and population exposure, and for initializing and evaluating chemical weather forecasts. By the end of the current decade there are planned geostationary Earth orbit (GEO) satellite missions for atmospheric composition over North America, East Asia and Europe with additional missions proposed. Together, these present the possibility of a constellation of geostationary platforms to achieve continuous time-resolved high-density observations of continental domains for mapping pollutant sources and variability on diurnal and local scales. We describe Observing System Simulation Experiments (OSSEs) to evaluate the contributions of these GEO missions to improve knowledge of near-surface air pollution due to intercontinental long-range transport and quantify chemical precursor emissions. Our approach uses an efficient computational method to sample a high-resolution global GEOS-5 chemistry Nature Run over each geographical region of the GEO constellation. The demonstration carbon monoxide (CO) observation simulator, which will be expanded to other chemical pollutants, currently produces multispectral retrievals (MOPITT-like) and captures realistic scene-dependent variation in measurement

Clasp/SJ Observation of Time Variations of Lyman-Alpha Emissions in a Solar Active Region

NASA Technical Reports Server (NTRS)

Ishikawa, S.; Kubo, M.; Katsukawa, Y.; Kano, R.; Narukage, N.; Ishikawa, R.; Bando, T.; Winebarger, A.; Kobayashi, K.; Trujillo Bueno, J.;

Age, gender, and skeletal variation in bone marrow composition: a preliminary study at 3.0 Tesla.

PubMed

Liney, Gary P; Bernard, Clare P; Manton, David J; Turnbull, Lindsay W; Langton, Chris M

2007-09-01

To evaluate the efficacy of MR Spectroscopy (MRS) at 3.0 Tesla for the assessment of normal bone marrow composition and assess the variation in terms of age, gender, and skeletal site. A total of 16 normal subjects (aged between eight and 57 years) were investigated on a 3.0 Tesla GE Signa system. To investigate axial and peripheral skeleton differences, non-water-suppressed spectra were acquired from single voxels in the calcaneus and lumbar spine. In addition, spectra were acquired at multiple vertebral bodies to assess variation within the lumbar spine. Data was also correlated with bone mineral density (BMD) measured in six subjects using dual-energy X-ray absorptiometry (DXA). Fat content was an order of magnitude greater in the heel compared to the spine. An age-related increase was demonstrated in the spine with values greater in men compared to female subjects. Significant trends in vertebral bodies within the same subjects were also shown, with fat content increasing L5 > L1. Population coefficient of variation (CV) was greater for fat fraction (FF) compared to BMD. Significant normal variations of marrow composition have been demonstrated, which provide important data for the future interpretation of patient investigations. (c) 2007 Wiley-Liss, Inc.

Observed variations of methane on Mars unexplained by known atmospheric chemistry and physics.

PubMed

Lefèvre, Franck; Forget, François

2009-08-06

The detection of methane on Mars has revived the possibility of past or extant life on this planet, despite the fact that an abiogenic origin is thought to be equally plausible. An intriguing aspect of the recent observations of methane on Mars is that methane concentrations appear to be locally enhanced and change with the seasons. However, methane has a photochemical lifetime of several centuries, and is therefore expected to have a spatially uniform distribution on the planet. Here we use a global climate model of Mars with coupled chemistry to examine the implications of the recently observed variations of Martian methane for our understanding of the chemistry of methane. We find that photochemistry as currently understood does not produce measurable variations in methane concentrations, even in the case of a current, local and episodic methane release. In contrast, we find that the condensation-sublimation cycle of Mars' carbon dioxide atmosphere can generate large-scale methane variations differing from those observed. In order to reproduce local methane enhancements similar to those recently reported, we show that an atmospheric lifetime of less than 200 days is necessary, even if a local source of methane is only active around the time of the observation itself. This implies an unidentified methane loss process that is 600 times faster than predicted by standard photochemistry. The existence of such a fast loss in the Martian atmosphere is difficult to reconcile with the observed distribution of other trace gas species. In the case of a destruction mechanism only active at the surface of Mars, destruction of methane must occur with an even shorter timescale of the order of approximately 1 hour to explain the observations. If recent observations of spatial and temporal variations of methane are confirmed, this would suggest an extraordinarily harsh environment for the survival of organics on the planet.

Inversion of gravity and bathymetry in oceanic regions for long-wavelength variations in upper mantle temperature and composition

NASA Technical Reports Server (NTRS)

Solomon, Sean C.; Jordan, Thomas H.

1993-01-01

Long-wavelength variations in geoid height, bathymetry, and SS-S travel times are all relatable to lateral variations in the characteristic temperature and bulk composition of the upper mantle. The temperature and composition are in turn relatable to mantle convection and the degree of melt extraction from the upper mantle residuum. Thus the combined inversion of the geoid or gravity field, residual bathymetry, and seismic velocity information offers the promise of resolving fundamental aspects of the pattern of mantle dynamics. The use of differential body wave travel times as a measure of seismic velocity information, in particular, permits resolution of lateral variations at scales not resolvable by conventional global or regional-scale seismic tomography with long-period surface waves. These intermediate scale lengths, well resolved in global gravity field models, are crucial for understanding the details of any chemical or physical layering in the mantle and of the characteristics of so-called 'small-scale' convection beneath oceanic lithosphere. In 1991 a three-year project to the NASA Geophysics Program was proposed to carry out a systematic inversion of long-wavelength geoid anomalies, residual bathymetric anomalies, and differential SS-S travel time delays for the lateral variation in characteristic temperature and bulk composition of the oceanic upper mantle. The project was funded as a three-year award, beginning on 1 Jan. 1992.

Overlap in genomic variation associated with milk fat composition in Holstein Friesian and Dutch native dual-purpose breeds.

PubMed

Maurice-Van Eijndhoven, M H T; Bovenhuis, H; Veerkamp, R F; Calus, M P L

2015-09-01

The aim of this study was to identify if genomic variations associated with fatty acid (FA) composition are similar between the Holstein-Friesian (HF) and native dual-purpose breeds used in the Dutch dairy industry. Phenotypic and genotypic information were available for the breeds Meuse-Rhine-Yssel (MRY), Dutch Friesian (DF), Groningen White Headed (GWH), and HF. First, the reliability of genomic breeding values of the native Dutch dual-purpose cattle breeds MRY, DF, and GWH was evaluated using single nucleotide polymorphism (SNP) effects estimated in HF, including all SNP or subsets with stronger associations in HF. Second, the genomic variation of the regions associated with FA composition in HF (regions on Bos taurus autosome 5, 14, and 26), were studied in the different breeds. Finally, similarities in genotype and allele frequencies between MRY, DF, GWH, and HF breeds were assessed for specific regions associated with FA composition. On average across the traits, the highest reliabilities of genomic prediction were estimated for GWH (0.158) and DF (0.116) when the 8 to 22 SNP with the strongest association in HF were included. With the same set of SNP, GEBV for MRY were the least reliable (0.022). This indicates that on average only 2 (MRY) to 16% (GWH) of the genomic variation in HF is shared with the native Dutch dual-purpose breeds. The comparison of predicted variances of different regions associated with milk and milk fat composition showed that breeds clearly differed in genomic variation within these regions. Finally, the correlations of allele frequencies between breeds across the 8 to 22 SNP with the strongest association in HF were around 0.8 between the Dutch native dual-purpose breeds, whereas the correlations between the native breeds and HF were clearly lower and around 0.5. There was no consistent relationship between the reliabilities of genomic prediction for a specific breed and the correlation between the allele frequencies of this breed

Ionosphere of venus: first observations of the effects of dynamics on the dayside ion composition.

PubMed

Taylor, H A; Brinton, H C; Bauer, S J; Hartle, R E; Cloutier, P A; Michel, F C; Daniell, R E; Donahue, T M; Maehl, R C

1979-02-23

Bennett radio-frequency ion mass spectrometers have returned the first in situ measurements of the Venus dayside ion composition, including evidence of pronounced structural variability resulting from a dynamic interaction with the solar wind. The ionospheric envelope, dominated above 200 kilometers by O(+), responds dramatically to variations in the solar wind pressure, Which is observed to compress the thermal ion distributions from heights as great as 1800 kilometers inward to 280 kilometers. At the thermal ion boundary, or ionopause, the ambient ions are swept away by the solar wind, such that a zone of accelerated suprathermnal plasma is encountered. At higher altitudes, extending outward on some orbits for thousands of kilometers to the bows shock, energetic ion currents are detected, apparently originating from the shocked solar wind plasma. Within the ionosphere, observations of pass-to-pass differences in the ion scale heights are indicative of the effects of ion convection stimlulated by the solar wind interaction.

ISEE-3 measurements of solar energetic particle composition

NASA Technical Reports Server (NTRS)

Von Rosenvinge, T. T.; Reames, D. V.

1980-01-01

Preliminary observations of energetic particles from solar flares beginning on September 23 and November 10, 1978 are reported. The measurements were made from the ISEE-3 spacecraft using very thin, large area solid-state detectors. Charge composition was measured for all elements from Z = 2 to Z = 26 above approximately 2 MeV/nucleon. More than 100,000 nuclei with Z greater than 2 were pulse-height analyzed during the course of the first event, while the second was substantially smaller. These good statistics enable the observation of variations in composition at low energies as a function of time. For example, the Fe/O ratio (2.0-3.1 MeV/n) was observed in the September event to decrease by a factor of approximately 5. By contrast, this same ratio increased by a factor of approximately 1.5 during the November 10 event. Similar variations have been reported earlier by Scholer et al. (1978). These authors, however were unable to observe the He/O ratio which has now been observed also to show significant variation.

Observation of subsecond variations in auroral region total electron content using 100 Hz sampling of GPS observables

NASA Astrophysics Data System (ADS)

McCaffrey, A. M.; Jayachandran, P. T.

2017-06-01

First ever auroral region total electron content (TEC) measurements at 100 Hz using a Septentrio PolaRxS Pro receiver are analyzed to discover ionospheric signatures which would otherwise be unobtainable with the frequently used lower sampling rates. Two types of variations are observed: small-magnitude (amplitude) variations, which are present consistently throughout the data set, and larger-magnitude (amplitude) variations, which are less frequent. Small-amplitude TEC fluctuations are accounted for by the receiver phase jitter. However, estimated secondary ionospheric effects in the calculation of TEC and the receiver phase jitter were unable to account for the larger-amplitude TEC fluctuations. These variations are also accompanied by fluctuations in the magnetic field, which seems to indicate that these fluctuations are real and of geophysical significance. This paper presents a technique and the capability of high-rate TEC measurements in the study of auroral dynamics. Further detailed study is needed to identify the cause of these subsecond TEC fluctuations and associated magnetic field fluctuations.

Spatial and temporal variation in dissolved organic carbon composition in a peaty catchment draining a windfarm

NASA Astrophysics Data System (ADS)

Zheng, Ying; Waldron, Susan; Flowers, Hugh

2015-04-01

Peatlands are an important terrestrial carbon reserve and a principal source of dissolved organic carbon (DOC) to the fluvial environment (Wallage et al. 2006). Recently it has been observed that DOC concentrations [DOC] in surface waters have increased in Europe and North America (Monteith et al. 2007). This has been attributed primarily to reduced acid deposition. However, land use change can also release C from peat soils. A significant land use change in Scotland is hosting windfarms. Whether windfarm construction causes such impacts has been a research focus, particularly considering fluvial losses, but usually assessing if there are changes in DOC concentration rather than composition. Our study area is a peaty catchment that hosts wind turbines, has peat restoration activities and forest felling and is drained by two streams. We are using UV-visible and fluorescence spectrophotometry to assess if there are differences between the two steams or temporal changes in DOC composition. We will present data from samples collected since February 2014. The parameters we are focusing on are SUVA254, E4/E6 and E2/E4 ratios as these are indicators of DOC aromaticity, humic acid (HA): fulvic acid (FA) ratio and the proportion of humic substances in DOC (Weishaar, 2003; Spencer et al. 2007; Graham et al. 2012). To assess these we have measured UV-visible absorbance spectra from 200 nm to 800 nm. Meanwhile sample fluorescence emission and excitation matrix (EEM) will be applied with the PARAFAC model to obtain more information about the variations in humic substances in this catchment. Our current analysis indicates spatial differences not only in DOC concentration but also in composition. For example, the mainstem draining the windfarm area had a smaller [DOC] but higher E4/E6 and lower E2/E4 ratio values than the tributary draining an area of felled forestry. This may be indicative of more HAs in the mainstem DOC. Seasonal variations have also been observed. Both streams

The Magmatic Structure of Mid-ocean Ridges: Integrating Geophysical and Petrological Observations

NASA Astrophysics Data System (ADS)

Maclennan, J.; Singh, S.

Geophysical surveys, petrological observations and numerical models have all played an important role in the study of magmatic processes at mid-ocean ridges. However, few studies have attempted to integrate the constraints from both geophysical and geochemical observations in order to develop models of mid-ocean ridges. Composi- tional variation within the oceanic crust must be considered when geophysical models are interpreted in terms of variation in temperature or fluid fraction. Modellers com- monly assume that the crust is compositionally homogeneous and that the relationship between temperature and melt fraction does not vary within the crust. However, the compositions of oceanic crustal rocks collected from the Oman ophiolite vary widely and their predicted solidus temperatures vary from 990­1240C and their liquidus temperatures from 1250­1700C. Compositional variation within the solid part of the oceanic crust causes variation in seismic velocities. At fixed temperature and pressure the compositional variation present in crustal rocks can give P-wave velocity variation of 1 km s-1 or more. This has the same effect as a temperature variation of 1500C in the solid or of a variation of 20% in the melt fraction. The importance of this petrolog- ical framework for the interpretation of the seismic structure of mid-ocean ridges and for the development of thermal models of oceanic crustal accretion is demonstrated using an example from the East Pacific Rise near 9N.

Compositional variability of the Martian surface

NASA Technical Reports Server (NTRS)

Adams, John B.; Smith, Milton O.

1991-01-01

Spectral reflectance data from Viking Landers and Orbiters and from telescopic observations were analyzed with the objective of isolating compositional information about the Martian surface and assessing compositional variability. Two approaches were used to calibrate the data to reflectance to permit direct comparisons with laboratory reference spectra of well characterized materials. In Viking Lander multispectral images (six spectral bands) most of the spectral variation is caused by changes in lighting geometry within individual scenes, from scene to scene, and over time. Lighting variations are both wavelength independent and wavelength dependent. By calibrating lander image radiance values to reflectance using spectral mixture analysis, the possible range of compositions was assessed with reference to a collection of laboratory samples, also resampled to the lander spectral bands. All spectra from the lander images studied plot (in six-space) within a planar triangle having at the apexes the respective spectra of tan basaltic palagonite, gray basalt, and shale. Within this plane all lander spectra fit as mixtures of these three endmembers. Reference spectra that plot outside of the triangle are unable to account for the spectral variation observed in the images.

Are Observed Variations of Topography of The '660' Influenced By Lateral Variations of An Underlying Interface ?

NASA Astrophysics Data System (ADS)

Castillo, J.; Mocquet, A.; Vacher, P.; Sotin, C.

Most global studies of lateral variations of topography of the '660' have been per- formed so far with long-period data. This presentation assess the seismic signature of this region when studied with broadband data in the frequency range 0.1-1 Hz. When sampled with P-to-s converted phases, this region shows a complex pattern, associat- ing 3 interfaces at the average depths of 600, 650 and 715 km. First results indicate that lateral topography variations of the '650' fit previous observations by long-period data (Gu et al., 1998), except in some subduction zones, especially in East Asia, where vari- ation trends appear to behave in an opposite way. In such regions, better correlations are found with the behaviour of the '715'. We propose that the seismic signature of long-period waves generated at the bottom of the transition zone may be influenced by both interfaces. Because of the lateral variations of their thickness and velocity jump as a function of thermal context, the signature of one interface could prevail against the other. The transformation of garnet into perovskite, and dissociation of ringwood- ite are tested as possible candidates for the '715' and '650', respectively (Vacher et al., 1998), using available thermoelastic data. Synthetic modelling of converted phases on the velocity profiles computed in different thermal contexts can explain our broadband observations. References : Gu et al., EPSL, 157, 57-67, 1998 ; Vacher et al., PEPI, 106, 275-298, 1998.

Compositional differences in simulated root exudates elicit a limited functional and compositional response in soil microbial communities.

PubMed

Strickland, Michael S; McCulley, Rebecca L; Nelson, Jim A; Bradford, Mark A

2015-01-01

Inputs of low molecular weight carbon (LMW-C) to soil - primarily via root exudates- are expected to be a major driver of microbial activity and source of stable soil organic carbon. It is expected that variation in the type and composition of LMW-C entering soil will influence microbial community composition and function. If this is the case then short-term changes in LMW-C inputs may alter processes regulated by these communities. To determine if change in the composition of LMW-C inputs influences microbial community function and composition, we conducted a 90 day microcosm experiment whereby soils sourced from three different land covers (meadows, deciduous forests, and white pine stands) were amended, at low concentrations, with one of eight simulated root exudate treatments. Treatments included no addition of LMW-C, and the full factorial combination of glucose, glycine, and oxalic acid. After 90 days, we conducted a functional response assay and determined microbial composition via phospholipid fatty acid analysis. Whereas we noted a statistically significant effect of exudate treatments, this only accounted for ∼3% of the variation observed in function. In comparison, land cover and site explained ∼46 and ∼41% of the variation, respectively. This suggests that exudate composition has little influence on function compared to site/land cover specific factors. Supporting the finding that exudate effects were minor, we found that an absence of LMW-C elicited the greatest difference in function compared to those treatments receiving any LMW-C. Additionally, exudate treatments did not alter microbial community composition and observable differences were instead due to land cover. These results confirm the strong effects of land cover/site legacies on soil microbial communities. In contrast, short-term changes in exudate composition, at meaningful concentrations, may have little impact on microbial function and composition.

Intrinsic Charge Trapping Observed as Surface Potential Variations in diF-TES-ADT Films.

PubMed

Hoffman, Benjamin C; McAfee, Terry; Conrad, Brad R; Loth, Marsha A; Anthony, John E; Ade, Harald W; Dougherty, Daniel B

2016-08-24

Spatial variations in surface potential are measured with Kelvin probe force microscopy for thin films of 2,8-difluoro-5,11-bis(triethylsilylethynyl)anthradithiophenes (diF-TES-ADT) grown on SiO2 and silane-treated SiO2 substrates by organic molecular beam deposition. The variations are observed both between and within grains of the polycrystalline organic film and are quantitatively different than electrostatic variations on the substrate surfaces. The skewness of surface potential distributions is larger on SiO2 than on HMDS-treated substrates. This observation is attributed to the impact of substrate functionalization on minimizing intrinsic crystallographic defects in the organic film that can trap charge.

A mechanism of midlatitude noontime foE long-term variations inferred from European observations

NASA Astrophysics Data System (ADS)

Mikhailov, A. V.; Perrone, L.; Nusinov, A. A.

2017-04-01

Manually scaled June noontime monthly median foE values at three European stations Rome, Juliusruh, and Slough/Chilton were used to understand the mechanism of foE long-term variations. The 11 year running mean smoothed foE manifests long-term (for some solar cycles) variations with the rising phase at the end of 1960-1985 and the falling phase after 1985. A close relationship (even in details) between (foEave)11y and (R12)11y variations with the correlation coefficient of 0.996 (absolutely significant according to Fisher F criterion) suggests that the Sun is the source of these (foEave)11y long-term variations. After removing solar activity long-term variations the residual (foEave)11y trend is very small ( 0.029% per decade) being absolutely insignificant. This means that all (foEave)11y variations are removed with one solar activity index, (R12)11y, i.e., this means that long-term variations are fully controlled by solar activity. Theory of midlatitude daytime E region tells us that long-term variations of solar EUV in two lines λ = 977 Å (CIII) and λ = 1025.7 Å (HLyβ) and X-ray radiation with λ < 100 Å (both manifesting the same long-term variations with the rising phase at the end of 1960-1985 and the falling phase after 1985) are responsible for the observed (foEave)11y variations. Therefore, the observed daytime midlatitude foE long-term variations have a natural (not anthropogenic) origin related to long-term variations of solar activity. No peculiarities in relation with the last deep solar minimum in 2008-2009 have been revealed.

Variation in Content Coverage by Classroom Composition: An Analysis of Advanced Math Course Content

ERIC Educational Resources Information Center

Covay, Elizabeth

2011-01-01

Everyone knows that there is racial inequality in achievement returns from advanced math; however, they do not know why black students and white students taking the same level of math courses are not leaving with the same or comparable skill levels. To find out, the author examines variation in course coverage by the racial composition of the…

Crack healing in cross-ply composites observed by dynamic mechanical analysis

NASA Astrophysics Data System (ADS)

Nielsen, Christian; Nemat-Nasser, Sia

2015-03-01

Cross-ply composites with healable polymer matrices are characterized using dynamic mechanical analysis (DMA). The [90,0]s samples are prepared by embedding layers of unidirectional glass or carbon fibers in 2MEP4FS, a polymer with thermally reversible covalent cross-links, which has been shown to be capable of healing internal cracks and fully recovering fracture toughness when the crack surfaces are kept in contact. After fabrication, cracks in the composites' transverse plies are observed due to residual thermal stresses introduced during processing. Single cantilever bending DMA measurements show the samples exhibit periods of increasing storage moduli with increasing temperature. These results are accurately modeled as a one-dimensional composite, which captures the underlying physics of the phenomenon. The effect of cracks on the stiffness is accounted for by a shear-lag model. The predicted crack density of the glass fiber composite is shown to fall within a range observed from microscopy images. Crack healing occurs as a function of temperature, with chemistry and mechanics-based rationales given for the onset and conclusion of healing. The model captures the essential physics of the phenomenon and yields results in accord with experimental observations.

Compositional variations at ultra-structure length scales in coral skeleton

NASA Astrophysics Data System (ADS)

Meibom, Anders; Cuif, Jean-Pierre; Houlbreque, Fanny; Mostefaoui, Smail; Dauphin, Yannicke; Meibom, Karin L.; Dunbar, Robert

2008-03-01

Distributions of Mg and Sr in the skeletons of a deep-sea coral ( Caryophyllia ambrosia) and a shallow-water, reef-building coral ( Pavona clavus) have been obtained with a spatial resolution of 150 nm, using the NanoSIMS ion microprobe at the Muséum National d'Histoire Naturelle in Paris. These trace element analyses focus on the two primary ultra-structural components in the skeleton: centers of calcification (COC) and fibrous aragonite. In fibrous aragonite, the trace element variations are typically on the order of 10% or more, on length scales on the order of 1-10 μm. Sr/Ca and Mg/Ca variations are not correlated. However, Mg/Ca variations in Pavona are strongly correlated with the layered organization of the skeleton. These data allow for a direct comparison of trace element variations in zooxanthellate and non-zooxanthellate corals. In both corals, all trace elements show variations far beyond what can be attributed to variations in the marine environment. Furthermore, the observed trace element variations in the fibrous (bulk) part of the skeletons are not related to the activity of zooxanthellae, but result from other biological activity in the coral organism. To a large degree, this biological forcing is independent of the ambient marine environment, which is essentially constant on the growth timescales considered here. Finally, we discuss the possible detection of a new high-Mg calcium carbonate phase, which appears to be present in both deep-sea and reef-building corals and is neither aragonite nor calcite.

Wave Effects Related to Altitude Variations in the Ion Composition of the Ionosphere

NASA Astrophysics Data System (ADS)

Vavilov, D. I.; Shklyar, D. R.

2016-12-01

Properties of the waves, which can propagate in a magnetized plasma in the frequency range below the proton gyrofrequency, depend strongly on the ion composition of the plasma. Addition of a new sort of ions leads to the appearance of a new resonance frequency, at which the refractive index becomes infinite, and a new cutoff frequency, at which the refractive index becomes zero. In this case, the topology of frequency dependence of the squared refractive index changes. Specifically, a new oscillation branch appears, which is located above the cutoff frequency. A question arises whether these oscillations are excited if radiation with the corresponding frequency, which propagates in a different mode, is present in the plasma. A linear transformation of the waves is another important effect, which is related to variations in the ion plasma composition. These two issues, which are directly related to the theory of formation of proton whistlers in the ionosphere, where the ion composition varies with altitude, are considered in this work.

Seasonal variations in the composition of the essential oils of Lavandula angustifolia (Lamiacae).

PubMed

Lakusić, Branislava; Lakusić, Dmitar; Ristić, Mihailo; Marcetić, Mirjana; Slavkovska, Violeta

2014-06-01

Seasonal variations in the composition of the essential oils obtained from the same individual (of the same genotype) of Lavandula angustifolia cultivated in Belgrade were determined by GC and GC/MS. The main constituents were 1,8-cineole (7.1-48.4%), linalool (0.1-38.7%), bomeol (10.9-27.7%), beta-phellandrene (0.5-21.2%) and camphor (1.5-15.8%). Cluster analysis showed that the 21 samples collected each month during the vegetation cycle were separable into three main clades with different compositions of essential oils. In the shoots with flowers, inflorescences and fruits of clade I, linalool is dominant, in the young leaves before flowering and old leaves of clade II, 1,8-cineole is dominant. In the young and incompletely developed leaves of clade III, beta-phellandrene is dominant. The composition of the essential oils of lavender depended on the plant part and the stage of development.

Temporal and local variations in biochemical composition of Crassostrea gigas shells

NASA Astrophysics Data System (ADS)

Almeida, Maria J.; Machado, Jorge; Moura, Gabriela; Azevedo, Manuela; Coimbra, João

1998-12-01

The objective of this work was to find relations between organic and inorganic shell components. Crassostrea gigas shells were analysed from live specimens collected at five different stations: the Lima estuary (1), the Ria de Aveiro (2, 3), and the Mondego estuary (4, 5), Portugal. About 30% of the oysters, from stations 1, 2 and 3 had shell-thickness-index values ≤10, indicating a severe thickening. Oysters from the Mondego estuary contained mud blisters due to Polydora infestations. Oysters from station 3 had thicker shells and showed a higher Pb content in shell and tissues than oysters from the other stations. Amino-acid composition changed mainly according to the modified protein (jelly-like substance) probably produced by the presence of TBT (tributyltin) in the water; in particular, we observed an increase in glutamic acid and threonine and a decrease in major amino acids such as aspartic acid, serine and glycine. Elemental shell composition was mainly associated with environmental conditions: shells from stations in open areas had higher Li, Cd, Cr and Ca and lower Mn levels than those from semi-enclosed areas (fish farms). Discriminant analyses against the three kinds of shell observed (normal, thick and infested), using chemical elements and amino acids as discriminant variables, showed the infested group to have the biggest differences. There was no correlation between amino-acid and chemical-element patterns in shell composition. Observed changes in amino-acid pattern, probably due to TBT, did not imply a simultaneous change of elemental composition.

Extensive Natural Intraspecific Variation in Stoichiometric (C:N:P) Composition in Two Terrestrial Insect Species

PubMed Central

Bertram, S. M.; Bowen, M.; Kyle, M.; Schade, J. D.

2008-01-01

Heterotrophic organisms must obtain essential elements in sufficient quantities from their food. Because plants naturally exhibit extensive variation in their elemental content, it is important to quantify the within-species stoichiometric variation of consumers. If extensive stoichiometric variation exists, it may help explain consumer variation in life-history strategy and fitness. To date, however, research on stoichiometric variation has focused on interspecific differences and assumed minimal intraspecific differences. Here this assumption is tested. Natural variation is quantified in body stoichiometry of two terrestrial insects: the generalist field cricket, Gryllus texensis Cade and Otte (Orthoptera: Gryllidae) and a specialist curculionid weevil, Sabinia setosa (Le Conte) (Coleoptera: Curculionidae). Both species exhibited extensive intraspecific stoichiometric variation. Cricket body nitrogen content ranged from 8–12% and there was a four-fold difference in body phosphorus content, ranging from 0.32–1.27%. Body size explained half this stoichiometric variation, with larger individuals containing less nitrogen and phosphorus. Weevils exhibited an almost three-fold difference in body phosphorus content, ranging from 0.38–0.97%. Overall, the variation observed within each of these species is comparable to the variation previously observed across almost all terrestrial insect species. PMID:20298114

Bayesian Analysis Of HMI Solar Image Observables And Comparison To TSI Variations And MWO Image Observables

NASA Astrophysics Data System (ADS)

Parker, D. G.; Ulrich, R. K.; Beck, J.

2014-12-01

We have previously applied the Bayesian automatic classification system AutoClass to solar magnetogram and intensity images from the 150 Foot Solar Tower at Mount Wilson to identify classes of solar surface features associated with variations in total solar irradiance (TSI) and, using those identifications, modeled TSI time series with improved accuracy (r > 0.96). (Ulrich, et al, 2010) AutoClass identifies classes by a two-step process in which it: (1) finds, without human supervision, a set of class definitions based on specified attributes of a sample of the image data pixels, such as magnetic field and intensity in the case of MWO images, and (2) applies the class definitions thus found to new data sets to identify automatically in them the classes found in the sample set. HMI high resolution images capture four observables-magnetic field, continuum intensity, line depth and line width-in contrast to MWO's two observables-magnetic field and intensity. In this study, we apply AutoClass to the HMI observables for images from May, 2010 to June, 2014 to identify solar surface feature classes. We use contemporaneous TSI measurements to determine whether and how variations in the HMI classes are related to TSI variations and compare the characteristic statistics of the HMI classes to those found from MWO images. We also attempt to derive scale factors between the HMI and MWO magnetic and intensity observables. The ability to categorize automatically surface features in the HMI images holds out the promise of consistent, relatively quick and manageable analysis of the large quantity of data available in these images. Given that the classes found in MWO images using AutoClass have been found to improve modeling of TSI, application of AutoClass to the more complex HMI images should enhance understanding of the physical processes at work in solar surface features and their implications for the solar-terrestrial environment. Ulrich, R.K., Parker, D, Bertello, L. and

Variations in the Geometry of the Sun Observed with HMI/SDO during Cycle 24

NASA Astrophysics Data System (ADS)

Irbah, Abdenour; Damé, Luc

2016-10-01

Geometry of the Sun and its temporal variations observed with ground-based instruments are still subject to questioning. The geometry, which inform us on the interior of the Sun, is achieved by high resolution measurements of the radius, oblateness and gravitational moments c2 and c4. Several space missions were developed these last decades to validate or refute its observed variations with ground experiments and the link with solar activity. High angular resolution of solar radius measurements and its long term trend is however a challenge in Space. The first attempts with MDI (Soho) then SODISM (PICARD) and HMI (SDO) revealed the difficulties of such measures due to hostile environment which introduces thermal variations of the instruments along the satellite orbit. These variations have non negligible impacts on optical properties of onboard telescopes and therefore on images and parameters extracted, such as the solar radius. We need to take into account the thermal behavior (housekeeping data) recorded together with the science data to correct them. Solar oblateness and gravitational moments ask for both special spacecraft operations and appropriate processing methods to obtain the needed accuracy for their measurements. We present here some results on the solar radius and oblateness obtained with HMI data. Images analysed cover six years since May 1, 2010 (beginning of Cycle 24), until now. Results show that the geometry of the Sun presents some temporal variations related to solar activity. In particular we evidence a Quasi-Biennale Oscillation (QBO) correlated with the solar cycle, as was observed with ground observations.

Observations of Transient ISS Floating Potential Variations During High Voltage Solar Array Operations

NASA Technical Reports Server (NTRS)

Willis, Emily M.; Minow, Joseph I.; Parker, Linda N.; Pour, Maria Z. A.; Swenson, Charles; Nishikawa, Ken-ichi; Krause, Linda Habash

2016-01-01

The International Space Station (ISS) continues to be a world-class space research laboratory after over 15 years of operations, and it has proven to be a fantastic resource for observing spacecraft floating potential variations related to high voltage solar array operations in Low Earth Orbit (LEO). Measurements of the ionospheric electron density and temperature along the ISS orbit and variations in the ISS floating potential are obtained from the Floating Potential Measurement Unit (FPMU). In particular, rapid variations in ISS floating potential during solar array operations on time scales of tens of milliseconds can be recorded due to the 128 Hz sample rate of the Floating Potential Probe (FPP) pro- viding interesting insight into high voltage solar array interaction with the space plasma environment. Comparing the FPMU data with the ISS operations timeline and solar array data provides a means for correlating some of the more complex and interesting transient floating potential variations with mission operations. These complex variations are not reproduced by current models and require further study to understand the underlying physical processes. In this paper we present some of the floating potential transients observed over the past few years along with the relevant space environment parameters and solar array operations data.

Variations in body weight, food intake and body composition after long-term high-fat diet feeding in C57BL/6J Mice

PubMed Central

Yang, Yongbin; Smith, Daniel L.; Keating, Karen D.; Allison, David B.; Nagy, Tim R.

2014-01-01

Objective To investigate the variations in body weight, food intake and body composition of both male and female C57BL/6J mice during a diet-induced obesity (DIO) model with high-fat diet (HFD) feeding. Design and Methods Mice were individually housed and fed ad libitum either a low-fat diet (LFD, 10% calories from fat; n=15 male, n=15 female) or high-fat diet (HFD, 45% calories from fat; n=277 male, n=278 female) from 8 to 43 weeks of age. Body weight, food intake and body composition were routinely measured. Results Body weight was significantly increased with HFD (vs. LFD) in males from week 14 (p=0.0221) and in females from week 27 (P=0.0076). Fat mass and fat-free mass of all groups were significantly increased over time (all p<0.0001), with a large variation observed in fat mass. Baseline fat mass, fat-free mass and daily energy intake were significant predictors of future body weight for both sexes (p<0.0001). Baseline fat mass was a significant predictor of future body fat (p<0.0001). Conclusions Both males and females have large variations in fat mass, and this variability increases over time, while that of fat-free mass remains relatively stable. Sex differences exist in HFD responses and multivariate predicting models of body weight. PMID:24942674

Spatial Evolution of the Thickness Variations over a CFRP Laminated Structure

NASA Astrophysics Data System (ADS)

Davila, Yves; Crouzeix, Laurent; Douchin, Bernard; Collombet, Francis; Grunevald, Yves-Henri

2017-10-01

Ply thickness is one of the main drivers of the structural performance of a composite part. For stress analysis calculations (e.g., finite element analysis), composite plies are commonly considered to have a constant thickness compared to the reality (coefficients of variation up to 9% of the mean ply thickness). Unless this variability is taken into account reliable property predictions cannot be made. A modelling approach of such variations is proposed using parameters obtained from a 16-ply quasi-isotropic CFRP plate cured in an autoclave. A discrete Fourier transform algorithm is used to analyse the frequency response of the observed ply and plate thickness profiles. The model inputs, obtained by a mathematical representation of the ply thickness profiles, permit the generation of a representative stratification considering the spatial continuity of the thickness variations that are in good agreement with the real ply profiles spread over the composite part. A residual deformation FE model of the composite plate is used to illustrate the feasibility of the approach.

Observed diurnal variations in Mars Science Laboratory Dynamic Albedo of Neutrons passive mode data

NASA Astrophysics Data System (ADS)

Tate, C. G.; Moersch, J.; Jun, I.; Mitrofanov, I.; Litvak, M.; Boynton, W. V.; Drake, D.; Fedosov, F.; Golovin, D.; Hardgrove, C.; Harshman, K.; Kozyrev, A. S.; Kuzmin, R.; Lisov, D.; Maclennan, E.; Malakhov, A.; Mischna, M.; Mokrousov, M.; Nikiforov, S.; Sanin, A. B.; Starr, R.; Vostrukhin, A.

2018-06-01

The Mars Science Laboratory Dynamic Albedo of Neutrons (DAN) experiment measures the martian neutron leakage flux in order to estimate the amount of water equivalent hydrogen present in the shallow regolith. When DAN is operating in passive mode, it is sensitive to neutrons produced through the interactions of galactic cosmic rays (GCR) with the regolith and atmosphere and neutrons produced by the rover's Multi-Mission Radioisotope Thermoelectric Generator (MMRTG). During the mission, DAN passive mode data were collected over the full diurnal cycle at the locations known as Rocknest (sols 60-100) and John Klein (sols 166-272). A weak, but unexpected, diurnal variation was observed in the neutron count rates reported at these locations. We investigate different hypotheses that could be causing these observed variations. These hypotheses are variations in subsurface temperature, atmospheric pressure, the exchange of water vapor between the atmosphere and regolith, and instrumental effects on the neutron count rates. Our investigation suggests the most likely factors contributing to the observed diurnal variations in DAN passive data are instrumental effects and time-variable preferential shielding of alpha particles, with other environmental effects only having small contributions.

Variations of the aerosol concentration and chemical composition over the arid steppe zone of Southern Russia in summer

NASA Astrophysics Data System (ADS)

Artamonova, M. S.; Gubanova, D. P.; Iordanskii, M. A.; Lebedev, V. A.; Maksimenkov, L. O.; Minashkin, V. M.; Obvintsev, Y. I.; Chketiani, O. G.

2016-12-01

Variations in the surface aerosol over the arid steppe zone of Southern Russia have been measured. The parameters of atmospheric aerosol (mass concentration, both dispersed and elemental compositions) and meteorological parameters were measured in Tsimlaynsk raion (Rostov oblast). The chemical composition of aerosol particles in the atmospheric surface layer has been determined, and the coefficients of enrichment of elements with respect to clarkes in the Earth's crust have been calculated. It is shown that, in summer, arid aerosols are transported from both alkaline and sandy soils of Kalmykia to the air basin over the observation zone. Aerosol particles in the surface air layer over this region have been found to contain the products of combustion of oil, coal, and ethylized fuel. These combustion products make a small contribution to the total mass concentration of atmospheric aerosol; however, they are most hazardous to the health of people because of their sizes and heavy-metal contents. A high concentration of submicron sulfur-containing aerosol particles of chemocondensation nature has been recorded. Sources of aerosol of both natural and anthropogenic origins in southern Russia are discussed.

Genome-wide association study of Arabidopsis thaliana identifies determinants of natural variation in seed oil composition

USDA-ARS?s Scientific Manuscript database

The renewable source of highly reduced carbon provided by plant triacylglycerols fills an ever increasing demand for food, biodiesel and industrial chemicals. Each of these uses requires different compositions of fatty acid proportions in seed oils. Identifying the genes responsible for variation in...

Semiannual variations in the neutral composition.

NASA Technical Reports Server (NTRS)

Mayr, H. G.; Volland, H.

1971-01-01

Meteor trail observations of the meridional mesospheric wind field are analyzed in terms of spherical harmonics, showing a predominance in the P3 term for the semiannual component. This suggests two heat sources for the semiannual variations. One that peaks at the equator is associated with the semiannual migration of the sun between the two hemispheres. A second heat input of greater magnitude that peaks at high latitudes is presumably related to auroral heating associated with the semiannual component in the occurrence of magnetic storms. The wind circulation, consistent with these sources, is shown to cause a semiannual redistribution of the minor constituent O in the lower thermosphere with the effects of decreasing the ratios of O/N2 and O/O2 at high latitudes and of enhancing these ratios at mid to low latitudes during equinox.

Compositional Variation in Magmas Supplied to the Southern East Pacific Rise, 17°-19° S: Implications for Magma Reservoir Dynamics

NASA Astrophysics Data System (ADS)

Bergmanis, E. C.; Sinton, J. M.; Rubin, K. H.; Gregg, T. K.; Cormier, M.

2002-12-01

Fine-scale observation and sampling of lavas from the southern EPR 17°-19° S reveal both short- and long-term compositional heterogeneity of flows produced in single eruptive episodes. Located between 17° 24' and 17° 36'S, the 140 x 106 m2 Aldo-Kihi flow reaches a maximum width of 2.2 km between 17° 26' and 17° 28'S; the presence of sheet flows, lava channels, and summit collapse troughs imply that the eruption was centered in this area of broad axial morphology. Some lava channels and collapsed lava tubes extend beyond the margins of the recently erupted Aldo-Kihi flow, indicating that lava distribution systems can persist over at least several hundreds of years and multiple separate eruptions were apparently centered in this region. Extensive glass analyses of the Aldo-Kihi flow show that MgO contents range from 7.7-8.4 wt %; all the samples with greater than 8.0 wt % MgO occur south of 17° 30'S. This result is hard to reconcile with along-axis propagation of a single dike, and suggests vertical eruption from a magma chamber that is compositionally zoned along-axis. Twenty-three other samples older than Aldo-Kihi contain > 8.0 wt % MgO; all but two occur south of 17° 28.4'S suggesting that the displacement of eruptive centers from the location of hottest subaxial magma is a long-lived feature of this region. Lack of compositional variation across some contacts indicates that this length of ridge has erupted compositionally similar lavas in separate volcanic episodes. Elsewhere distinctly different lava compositions include the several-hundred-year-old Rehu-Marka Fe-Ti basalt, and local occurrences of incompatible element-enriched T-MORB. The distribution of rock types in this area requires a complex history of mantle melting, recharge, cooling, and eruption that has been spatially systematic over time scales encompassing several eruptive episodes. Between 18° 31.5' and 18° 34.5'S the South Hump lava is distinctly bimodal with highly evolved ferrobasalts

Observation of CO2 in Comet C/2012 K5 LINEAR

NASA Astrophysics Data System (ADS)

McKay, Adam; Kelley, Michael; DiSanti, Michael; Chanover, Nancy

2012-12-01

The study of cometary composition is important to understanding the formation and evolution of our solar system. Comets have undergone very little thermal evolution in their lifetimes, which results in their near pristine composition. The nucleus of a comet is very rarely detected directly. Instead, we observe the coma that surrounds the nucleus. Physical and chemical processes in the coma affect its composition, and therefore coma composition is not a direct representation of nuclear composition. An important trend is the observed variation of coma composition with heliocentric distance, most likely influenced by the volatility of the main surface ices, H2O, CO2, and CO. Infrared studies of these molecules are complicated by telluric features, so often daughter molecules of these species such as OH are observed instead. A potentially effective tracer for these primary ices is atomic oxygen in the coma. However, the relationship between these ices and atomic oxygen is only understood at a qualitative level. We propose to use Spitzer observations in IRAC's 4.5 micron band pass to observe the CO2 v3 band at 4.26 microns in comet C/2012 K5 LINEAR. These observations will be coordinated with observations of atomic oxygen obtained at Apache Point Observatory and observations of H2O at Keck. These near simultaneous observations of H2O, CO2, and atomic oxygen in a cometary coma will increase our understanding of the link between these primary ices and atomic oxygen. With a complete understanding of the relationship between atomic oxygen and the primary ices on the nucleus, observations of atomic oxygen can serve as a powerful proxy for the production of these primary volatiles and aid our understanding of the variation in coma composition as a function of heliocentric distance, and therefore the composition of the nucleus and how our solar system was formed.

Seasonal Variations in Maternal Provisioning of Crepidula fornicata (Gastropoda): Fatty Acid Composition of Females, Embryos and Larvae

PubMed Central

Leroy, Fanny; Meziane, Tarik; Riera, Pascal; Comtet, Thierry

2013-01-01

Recruitment success of marine invertebrate populations not only depends on the number of recruits but also on their quality which affects their survival. In species characterized by a mixed development (encapsulated embryonic development and release of planktotrophic larvae), the offspring quality depends on both maternal provisioning and larval feeding. Here, we investigated potential changes of maternal provisioning over the whole reproductive period in a gastropod with a mixed development: Crepidula fornicata . In its introduction area, C . fornicata reproduces from February to October, which implies that both adults and larvae are exposed to different food availabilities. Maternal provisioning was assessed by measuring the fatty acid (FA) composition of females, encapsulated embryos and larvae, in February, May, July and September 2009. FA are essential resources for the development of embryos and larvae, and are key biomarkers of offspring quality. Our results showed differences in FA composition between muscles, visceral masses, and encapsulated embryos. In particular, FA composition of embryos was similar to that of the visceral mass. Seasonal variations in FA composition were observed: in the middle of the reproductive season (May and July), female tissues and embryos showed a higher proportion of polyunsaturated fatty acids and especially ω3, as compared to the beginning and end of the reproductive season (February and September). This showed that through maternal provisioning the quality of C . fornicata offspring was higher in the middle of the reproductive season. Whether this would result in an increase of recruitment success and juvenile performance would require further investigations. PMID:24086505

Seasonal variations in maternal provisioning of Crepidula fornicata (Gastropoda): fatty acid composition of females, embryos and larvae.

PubMed

Leroy, Fanny; Meziane, Tarik; Riera, Pascal; Comtet, Thierry

2013-01-01

Recruitment success of marine invertebrate populations not only depends on the number of recruits but also on their quality which affects their survival. In species characterized by a mixed development (encapsulated embryonic development and release of planktotrophic larvae), the offspring quality depends on both maternal provisioning and larval feeding. Here, we investigated potential changes of maternal provisioning over the whole reproductive period in a gastropod with a mixed development: Crepidula fornicata. In its introduction area, C. fornicata reproduces from February to October, which implies that both adults and larvae are exposed to different food availabilities. Maternal provisioning was assessed by measuring the fatty acid (FA) composition of females, encapsulated embryos and larvae, in February, May, July and September 2009. FA are essential resources for the development of embryos and larvae, and are key biomarkers of offspring quality. Our results showed differences in FA composition between muscles, visceral masses, and encapsulated embryos. In particular, FA composition of embryos was similar to that of the visceral mass. Seasonal variations in FA composition were observed: in the middle of the reproductive season (May and July), female tissues and embryos showed a higher proportion of polyunsaturated fatty acids and especially ω3, as compared to the beginning and end of the reproductive season (February and September). This showed that through maternal provisioning the quality of C. fornicata offspring was higher in the middle of the reproductive season. Whether this would result in an increase of recruitment success and juvenile performance would require further investigations.

Diurnal Variations of Titan's Surface Temperatures From Cassini -CIRS Observations

NASA Astrophysics Data System (ADS)

Cottini, Valeria; Nixon, Conor; Jennings, Don; Anderson, Carrie; Samuelson, Robert; Irwin, Patrick; Flasar, F. Michael

The Cassini Composite Infrared Spectrometer (CIRS) observations of Saturn's largest moon, Titan, are providing us with the ability to detect the surface temperature of the planet by studying its outgoing radiance through a spectral window in the thermal infrared at 19 m (530 cm-1) characterized by low opacity. Since the first acquisitions of CIRS Titan data the in-strument has gathered a large amount of spectra covering a wide range of latitudes, longitudes and local times. We retrieve the surface temperature and the atmospheric temperature pro-file by modeling proper zonally averaged spectra of nadir observations with radiative transfer computations. Our forward model uses the correlated-k approximation for spectral opacity to calculate the emitted radiance, including contributions from collision induced pairs of CH4, N2 and H2, haze, and gaseous emission lines (Irwin et al. 2008). The retrieval method uses a non-linear least-squares optimal estimation technique to iteratively adjust the model parameters to achieve a spectral fit (Rodgers 2000). We show an accurate selection of the wide amount of data available in terms of footprint diameter on the planet and observational conditions, together with the retrieved results. Our results represent formal retrievals of surface brightness temperatures from the Cassini CIRS dataset using a full radiative transfer treatment, and we compare to the earlier findings of Jennings et al. (2009). The application of our methodology over wide areas has increased the planet coverage and accuracy of our knowledge of Titan's surface brightness temperature. In particular we had the chance to look for diurnal variations in surface temperature around the equator: a trend with slowly increasing temperature toward the late afternoon reveals that diurnal temperature changes are present on Titan surface. References: Irwin, P.G.J., et al.: "The NEMESIS planetary atmosphere radiative transfer and retrieval tool" (2008). JQSRT, Vol. 109, pp

Structure and Composition of the Distant Lunar Exosphere: Constraints from ARTEMIS Observations of Ion Acceleration in Time-Varying Fields

NASA Technical Reports Server (NTRS)

Halekas, J. S.; Poppe, A. R.; Farrell, W. M.; McFadden, J. P.

2016-01-01

By analyzing the trajectories of ionized constituents of the lunar exosphere in time-varying electromagnetic fields, we can place constraints on the composition, structure, and dynamics of the lunar exosphere. Heavy ions travel slower than light ions in the same fields, so by observing the lag between field rotations and the response of ions from the lunar exosphere, we can place constraints on the composition of the ions. Acceleration, Reconnection, Turbulence, and Electrodynamics of Moon's Interaction with the Sun (ARTEMIS) provides an ideal platform to utilize such an analysis, since its two-probe vantage allows precise timing of the propagation of field discontinuities in the solar wind, and its sensitive plasma instruments can detect the ion response. We demonstrate the utility of this technique by using fully time-dependent charged particle tracing to analyze several minutes of ion observations taken by the two ARTEMIS probes 3000-5000 km above the dusk terminator on 25 January 2014. The observations from this time period allow us to reach several interesting conclusions. The ion production at altitudes of a few hundred kilometers above the sunlit surface of the Moon has an unexpectedly significant contribution from species with masses of 40 amu or greater. The inferred distribution of the neutral source population has a large scale height, suggesting that micrometeorite impact vaporization and/or sputtering play an important role in the production of neutrals from the surface. Our observations also suggest an asymmetry in ion production, consistent with either a compositional variation in neutral vapor production or a local reduction in solar wind sputtering in magnetic regions of the surface.

Ecosystem composition changes over the past millennium: model simulations and comparison with paleoecological observations

NASA Astrophysics Data System (ADS)

Liu, Y.; Rollinson, C.; Dietze, M.; McLachlan, J. S.; Poulter, B.; Quaife, T. L.; Raiho, A.; Ricciuto, D. M.; Schaefer, K. M.; Steinkamp, J.; Moore, D. J.

2015-12-01

Over multi-decadal to multi-centennial timescales, ecosystem function and carbon storage is largely influenced by vegetation composition. The predictability of ecosystem responses to climate change thus depends on the understanding of long-term community dynamics. Our study aims to quantify the influence of the most relevant ecological factors that control plant distribution and abundance, in contemporary terrestrial biosphere models and in paleo-records, and constrain the model processes and parameters with paleoecological data. We simulated vegetation changes at 6 sites in the northeastern United States over the past 1160 years using 7 terrestrial biosphere models and variations (CLM4.5-CN, ED2, ED2-LU, JULES-TRIFFID, LINKAGES, LPJ-GUESS, LPJ-wsl) driven by common paleoclimatic drivers. We examined plant growth, recruitment, and mortality (including other carbon turnover) of the plant functional types (PFTs) in the models, attributed the responses to three major factors (climate, competition, and disturbance), and estimated the relative effect of each factor. We assessed the model responses against plant-community theories (bioclimatic limits, niche difference, temporal variation and storage effect, and disturbance). We found that vegetation composition were sensitive to realized niche differences (e.g. differential growth response) among PFTs. Because many models assume unlimited dispersal and sometimes recruitment, the "storage effect" constantly affects community composition. Fire was important in determining the ecosystem composition, yet the vegetation to fire feedback was weak in the models. We also found that vegetation-composition changes in the simulations were driven to a much greater degree by growth as opposed to by turnover/mortality, when compared with those in paleoecological records. Our work suggest that 1) for forecasting slow changes in vegetation composition, we can use paleo-data to better quantify the realized niches of PFTs and associated

Variation of atmospheric CO, δ13C, and δ18O at high northern latitude during 2004-2009: Observations and model simulations

NASA Astrophysics Data System (ADS)

Park, Keyhong; Wang, Zhihui; Emmons, Louisa K.; Mak, John E.

2015-10-01

Atmospheric CO mixing ratios and stable isotope ratios (δ13C and δ18O) were measured at a high northern latitude site (Westman Islands, Iceland) from January 2004 to March 2010 in order to investigate recent multiyear trends of the sources of atmospheric carbon monoxide in the extratropical Northern Hemisphere. During this period, we observed a decrease of about 2% per year in CO mixing ratios with little significant interannual variability. The seasonal cycles for δ13C and δ18O in CO are similar to that in the CO mixing ratio, and there is a pronounced interannual variation in their seasonal extremes occurring in summer and fall, which is driven by changes in the relative contribution of different sources. Some of the sources of CO are anthropogenic in character (e.g., fossil fuel and biofuel combustion and agricultural waste burning), and some are primarily natural (e.g., oxidation atmospheric methane and other hydrocarbons and wildfires), and distinction among the various major sources can, more or less, be distinguished by the stable isotopic composition of CO. We compare our observations with simulations from a 3-D global chemical transport model (MOZART-4, Model for Ozone and Related Chemical Tracers, version 4). Our results indicate the observed trend of anthropogenic CO emissions is mostly responsible for the observed variation in δ13C and δ18O of CO during 2004-2009. Especially, the δ18O enriched sources such as fossil fuel and biofuel sources are controlling the variation. The modeling results indicate decreasing trends in the fossil fuel and biofuel source contributions at Iceland of -0.61 ± 0.26 ppbv/yr and -0.38 ± 0.10 ppbv/yr, respectively, during the observation period.

Age and seasonal-dependent variations in the biochemical composition of boar semen.

PubMed

Fraser, L; Strzeżek, J; Filipowicz, K; Mogielnicka-Brzozowska, M; Zasiadczyk, L

2016-08-01

This study investigated the effect of age- and seasonal-related variations in the composition of boar semen over a 3-year period. At the onset of 8 months of age, ejaculates were collected from four boars and allocated into three groups: 8 to 18, 19 to 30, and 31 to 42 months and were divided into two seasonal periods: autumn-winter and spring-summer. Boar variability had a significant effect on most of the analyzed semen parameters. Significantly, higher ejaculate volumes were observed in the boars older than 18 months of age during the autumn-winter period. Sperm concentration was higher in boars less than the age of 18 months of age, whereas the total sperm numbers were significantly higher during the autumn-winter period, regardless of the age group. Seasonal effects in sperm motility were more marked in boars at the age of 19 to 30 months, being significantly higher during the autumn-winter period. The proportions of spermatozoa with intact, normal apical ridge acrosome, and osmotically tolerant acrosomal membranes were markedly higher in boars at the age of 19 to 30 months during the autumn-winter period. Spermatozoa harvested during the spring-summer period were more susceptible to lipid peroxidation, irrespective of the age group. Significantly, higher levels of protein content and concentrations of nonthiol-containing antioxidant components of the seminal plasma (SP) were detected in boars less than 18 months of age during the autumn-winter period. Seasonal effects on the pH and proteinase inhibitory activity in the SP were more marked in boars less than 18 months of age, whereas alkaline phosphatase activity was greater in boars at the age of 19 to 30 months during the autumn-winter period. Substantial amounts of the thiol-containing antioxidants of the SP were detected in boars older than 18 months of age during the spring-summer period. Neither osmolality nor total antioxidant status was affected by differences in the seasonal periods or age

Aerobic fitness does not modify the effect of FTO variation on body composition traits.

PubMed

Huuskonen, Antti; Lappalainen, Jani; Oksala, Niku; Santtila, Matti; Häkkinen, Keijo; Kyröläinen, Heikki; Atalay, Mustafa

2012-01-01

Poor physical fitness and obesity are risk factors for all cause morbidity and mortality. We aimed to clarify whether common genetic variants of key energy intake determinants in leptin (LEP), leptin receptor (LEPR), and fat mass and obesity-associated (FTO) are associated with aerobic and neuromuscular performance, and whether aerobic fitness can alter the effect of these genotypes on body composition. 846 healthy Finnish males of Caucasian origin were genotyped for FTO (rs8050136), LEP (rs7799039) and LEPR (rs8179183 and rs1137101) single nucleotide polymorphisms (SNPs), and studied for associations with maximal oxygen consumption, body fat percent, serum leptin levels, waist circumference and maximal force of leg extensor muscles. Genotype AA of the FTO SNP rs8050136 associated with higher BMI and greater waist circumference compared to the genotype CC. In general linear model, no significant interaction for FTO genotype-relative VO(2)max (mL·kg(-1)·min(-1)) or FTO genotype-absolute VO(2)max (L·min(-1)) on BMI or waist circumference was found. Main effects of aerobic performance on body composition traits were significant (p<0.001). Logistic regression modelling found no significant interaction between aerobic fitness and FTO genotype. LEP SNP rs7799039, LEPR SNPs rs8179183 and rs1137101 did not associate with any of the measured variables, and no significant interactions of LEP or LEPR genotype with aerobic fitness were observed. In addition, none of the studied SNPs associated with aerobic or neuromuscular performance. Aerobic fitness may not modify the effect of FTO variation on body composition traits. However, relative aerobic capacity associates with lower BMI and waist circumference regardless of the FTO genotype. FTO, LEP and LEPR genotypes unlikely associate with physical performance.

[Diet composition and ontogenetic variation in feeding habits of Cleithenes herzensteini in central Yellow Sea].

PubMed

Zhang, Bo

2007-08-01

In the bottom trawl surveys in central Yellow Sea from January 2004 to October 2005, 622 samples of plaice Cleithenes herzensteini were collected, and their stomach contents were analyzed. The results indicated that the prey items of the plaice included 11 groups or 38 prey species, but only Crustacea and Lamellibranchia were the most important prey groups, accounting for 99% of the total food composition by percentage of index of relative importance. Euphausia pacific, Crangon affinis and Tellinidae were the dominant prey species. Comparing with the 1980s, the feeding activity of plaice declined significantly, and the diet composition changed. Fishes were no longer the dominant prey, and the proportion of anchovy in the diet decreased. Cluster analysis and two-way contingency table analysis were used to study the ontogenetic variations in the feeding habits of plaice, and the results showed that the feeding activity of plaice did not vary significantly among 7 size classes within the size between 51 mm and 370 mm, but ontogenetic variations were found in the diet composition. In the size class < 119 mm, the diet mainly included Euphausiacea and Decapoda. In the diets of fish with the size between 120 mm and 199 mm, the proportion of Lamellibranchia and fishes increased markedly. In the size class > 200 mm, plaice mainly fed on Decapoda and fishes.

Voyager Observations of the Color of Saturn's Ring

NASA Technical Reports Server (NTRS)

Estrada, Paul R.; Cuzzi, Jeffrey N.; Morrison, David (Technical Monitor)

1994-01-01

Previously unreduced high resolution Voyager 2 images of Saturn's main rings are used to generate reflectivity (I/F) profiles as a function of radius. Ratios of profiles taken from green, violet, orange, and UV filter images are then produced. The I/F ratios are diagnostic of composition, and provide us with information on the rings' present state of compositional evolution. The rings are extremely reddish in color which suggests that they could not be pure water ice. The most likely candidates for the non-icy components are silicates and organics. The sources of these pollutants are of extreme importance in determining the compositional history of the rings. The radial profiles of ring color ratio exhibit several very interesting properties: (a) broad-scale, fairly smooth, color variations which are only weakly correlated with underlying ring structure (optical depth variations) across the outer C ring and inner B ring as well as the Cassini division region. These variations are probably consistent with ballistic transport; (b) fine-scale, noise-Like (but unquestionably real) color variations across at least the outer two-thirds of the B ring. Not only the "redness" but the spectral shape varies. These variations are currently unexplained. Groundbased spectroscopic observations should be pursued to study the implied compositional heterogeneities on at least the larger scales. This data set will be used for modeling of the color and composition of the main rings using ballistic transport and radiative transfer theories.

Variation of brine compositions resulting from flow from matrix or fracture permeability, investigated by high pressure laboratory experiments

NASA Astrophysics Data System (ADS)

Poszwa, A. C.; Coleman, M. L.; Pouya, A.; Ader, M.; Bounenni, A.

2003-04-01

Planning oil production from a chalk reservoir oilfield is difficult because the matrix usually has low permeability despite its high porosity. Most oil is thought to come from fracture porosity but the matrix contribution should increase as compaction occurs during production. To better understand the respective contributions from matrix and fracture, we studied the geochemical characteristics of fluids using high-pressure brine flow experiments on chalk cores. During the experiment axial load was changed relative to confining pressure to induce fractures and to close them again. We used chlorine stable isotope variations to study fluid pathway, because chlorine is a chemically conservative element in sedimentary systems and its isotopes fractionate only with physical processes like diffusion or adsorption that could occur mainly in the chalk matrix. A first experiment was performed on a very porous chalk from Henley (on-shore UK) and using a low-salinity brine. Large variations of brine Cl isotope composition were observed (from -0.56 to +0.08 per mil). The variations were correlated positively with the brine flux through the chalk and the permeability of the rock, both parameters controlled by the rock fracturing. A second experiment used brine with salinity similar to that of seawater. In this case, chemical and isotopic variations were not significant. From the beginning, the chalk structure seems to have been destroyed very quickly (induced fracture porosity collapsed) possibly because of the fluid nature, so that whatever pressure was applied, the permeability did not change significantly. Using Valhall reservoir chalk (offshore Norwegian North Sea) and fluid half the salinity of seawater in a third experiment, we obtained a large range of permeabilities. Brine isotopic trends were very similar on average to those of the first experiment even though variations were smaller (Cl isotopes from -0.09 to +0.29 per mil) and not significantly correlated simply to

Titan's Atmospheric Composition from Observations by the Cassini Infrared Spectrometer

NASA Technical Reports Server (NTRS)

Abbas, M. M.; LeClair, A.; Flasar, F. M.; Kunde, V. G.; Conrath, B. J.; Coustenis, A.; Jennings, D. J.; Nixon, C. A.; Brasunas, J.; Achterberg, R. K.

2006-01-01

The Composite Infrared Spectrometer (CIRS) aboard the Cassini spacecraft has been making observations during the fly-bys of Titan since the Saturn-Orbit-Insertion in July 2004. The observations provide infrared them1 emission spectra of Titan s atmosphere in three spectral channels covering the 10/cm to 1400/cm spectral region, with variable spectral resolutions of 0.53/cm and 2.8/cm. The uniquely observed spectra exhibit rotational and vibrational-rotational spectral lines of the molecular constituents of Titan s atmosphere that may be analyzed to retrieve information about the composition, thermal structure, and physical and dynamical processes in the remotely sensed atmosphere. We present an analysis of Titan's infrared spectra observed during July 2004 (TO), December 2004 (Tb) and February 2005 (T3), for retrieval of the stratospheric thermal structure, distribution of the hydrocarbons, nitriles, and oxygen bearing constituents, such as C2H2, C2H4, C2H6, C3H8, HCN, HC3N, CO, and CO2 . Preliminary results on the distribution and opacity of haze in Titan s atmosphere are discussed.

Regional variation in shea butter lipid and triterpene composition in four African countries.

PubMed

Di Vincenzo, Daria; Maranz, Steve; Serraiocco, Arnaldo; Vito, Raffaella; Wiesman, Zeev; Bianchi, Giorgio

2005-09-21

The triacylglycerol, fatty acid, and polycyclic triterpene compositions of shea butter were determined for 150 samples from the sub-Saharan countries of Mali, Burkina Faso, Nigeria, and Uganda. The compositional profiles showed high variability in all three classes of compounds. Shea butter is made up mainly of four triglycerides (TAG) differing in carbon number (CN) by two, starting from CN 50 to CN 56. The greatest source of variation was in the CN 54 TAG. Shea butter is characterized by 16 saturated and unsaturated fatty acids in greatly varying proportion, the major ones being the even homologues in the range of C(16)-C(20). Oleic acid is dominant in Ugandan provenances, whereas stearic acid is dominant in West African shea butter. Acetyl and cinnamyl polycyclic triterpene means for countries ranged from 3.69 to 12.57%, with the highest values found in Nigerian provenances. Statistical comparisons of fat composition show that the geographic distance between shea populations is reflected in the degree of separation of their chemical profiles.

Spacecraft observations of the solar wind composition

NASA Technical Reports Server (NTRS)

Bame, S. J.

1972-01-01

Solar wind composition studies by means of plasma analyzers carried on various spacecraft are reviewed. The average ratio of helium to hydrogen over the solar cycle is close to 0.045; values as low as 0.0025 and as high as 0.25 have been observed. High values have been observed following solar flares and interplanetary shock waves when the flare gas driving the shock arrives at the spacecraft. Ions of He-3(+2), O-16(+6), and O-16(+7) have been observed with Vela 3 electrostatic analyzers. Further measurements with Vela 5 analyzers have shown the presence of N-14(+6), Si-28(+7) to Si-28(+9) and Fe-56(+7) to Fe-56(+12) ions. The relative abundance of oxygen, silicon, and iron in the solar wind of July 6, 1969, was 1.00, 0.21, and 0.17, which is very similar to reported values for the corona. The ratio of helium to oxygen is variable; the average value of He/O is close to 100, but values between 30 and 400 have been observed.

Variations in the chemical composition of cassava ( Manihot esculenta Crantz) leaves and roots as affected by genotypic and environmental variation.

PubMed

Burns, Anna Elizabeth; Gleadow, Roslyn Margaret; Zacarias, Anabela M; Cuambe, Constantino Estevão; Miller, Rebecca Elizabeth; Cavagnaro, Timothy Richard

2012-05-16

The purpose of this study was to assess the quality of cassava cultivars, in terms of cyanogenic potential and composition of macro- and micronutrients, sampled from different locations in rural Mozambique. Total cyanide concentrations in fresh cassava tissues were measured using portable cyanide testing kits, and elemental nutrients were later analyzed from dried plant tissue. Variation in cyanogenic potential and nutrient composition occurred both among cultivars and across locations. The majority of cultivars contained >100 ppm total cyanide, fresh weight, and are therefore considered to be dangerously poisonous unless adequately processed before consumption. Leaf cyanogenic and nutrient content varied with plant water status, estimated using carbon isotope discrimination (δ(13)C). The colonization of roots of all cultivars by arbuscular mycorrhizal fungi was also quantified and found to be high, indicating that mycorrhizas could play a key role in plant nutrient acquisition in these low-input farming systems.

Between-Group Variation in Female Dispersal, Kin Composition of Groups, and Proximity Patterns in a Black-and-White Colobus Monkey (Colobus vellerosus)

PubMed Central

Wikberg, Eva C.; Sicotte, Pascale; Campos, Fernando A.; Ting, Nelson

2012-01-01

A growing body of evidence shows within-population variation in natal dispersal, but the effects of such variation on social relationships and the kin composition of groups remain poorly understood. We investigate the link between dispersal, the kin composition of groups, and proximity patterns in a population of black-and-white colobus (Colobus vellerosus) that shows variation in female dispersal. From 2006 to 2011, we collected behavioral data, demographic data, and fecal samples of 77 males and 92 females residing in eight groups at Boabeng-Fiema, Ghana. A combination of demographic data and a genetic network analysis showed that although philopatry was female-biased, only about half of the females resided in their natal groups. Only one group contained female-female dyads with higher average relatedness than randomly drawn animals of both sexes from the same group. Despite between-group variation in female dispersal and kin composition, female-female dyads in most of the study groups had higher proximity scores than randomly drawn dyads from the same group. We conclude that groups fall along a continuum from female dispersed, not kin-based, and not bonded to female philopatric, kin-based, and bonded. We found only partial support for the predicted link between dispersal, kin composition, and social relationships. In contrast to most mammals where the kin composition of groups is a good predictor of the quality of female-female relationships, this study provides further support for the notion that kinship is not necessary for the development and maintenance of social bonds in some gregarious species. PMID:23144951

The Io plasma torus during the Cassini encounter with Jupiter: Temporal, radial and azimuthal variations

NASA Astrophysics Data System (ADS)

Steffl, Andrew Joseph

During the Cassini spacecraft's flyby of Jupiter (1 October 2000 to 31 March 2001), the Ultraviolet Imaging Spectrograph (UVIS) produced an extensive dataset consisting of several thousand spectrally-dispersed images of the lo plasma torus. The temporal, radial, and azimuthal variability of the to plasma torus during this period are examined. The total EUV power radiated from the torus is found to be ~1.7 x 10 12 W with variations of 25%. Several events were observed during which the torus brightened by 20% over a few hours. Significant changes in the composition of the torus plasma were observed between 1 October 2000 and 11 November 2000. The composition and electron temperature of the torus plasma as a function of radial distance were derived from a scale of the midnight sector of the torus. The radial profile during the Cassini epoch shows significant differences from the Voyager era. The Io torus is found to exhibit significant azimuthal variations in ion composition. This compositional variation is observed to have a period of 10.07 hours 1.5% longer than the System III rotation period of Jupiter. While exhibiting many similar characteristics, the periodicity in the UVIS data is 1.3% shorter than the "System IV" period. The amplitude of the azimuthal variation of S II and S IV varies between 5-25% during the observing period, while the amplitude of the variation of S III and O II remains in the range of 2-5%. The amplitude of the azimuthal compositional asymmetry appears to be modulated by its location in System III longitude. The observed temporal variability is reproduced by models of the torus chemistry that include a factor of 3 increase in the rate of oxygen and sulfur atoms supplied to the extended neutral clouds that are the source of the torus plasma coupled with a ~35% increase in the amount of riot electrons in the Io torus. The observed azimuthal variability of the Io torus is well matched by models incorporating a primary source of hot electrons

Seasonal variation in nutritional composition of Kappaphycus alvarezii (Doty) Doty-an edible seaweed.

PubMed

Suresh Kumar, K; Ganesan, K; Subba Rao, P V

2015-05-01

Seasonal variation in the proximate and mineral composition of Kappaphycus alvarezii were investigated in the present study, moreover, the relationship between the nutritive components of this seaweed and the environment were also established. Carbohydrates represented the major portion of the algae (i.e. average total carbohydrate content was 23.01 ± 1.64 g/100 g DW), while the lipid content was the lowest among the constituents investigated (0.39 ± 0.04 to 0.91 ± 0.51 g/100 g DW). The protein content of K. alvarezii varied from 12.69 ± 0.6 to 23.61 ± 0.02 g/100 g DW, and the fiber content varied between 9.68 ± 0.08 to 18.57 ± 0.15 g/100 g DW. Highest total mineral content (29939.61 ± 9340.38 mg/100 g DW) was observed in April 2005, while least values were recorded in January 2006 i.e. (10997.62 ± 1120.26 mg/100 g DW). The Na/K ratio during the study ranged from 0.34 to 0.87. All the samples showed remarkable semi-refined carrageenan (SRC) yield ranging from 42.70 ± 1.07 to 63.73 ± 1.73 % (average 53.90 ± 1.37 %), and, the samples collected during December 2004 and January 2006 demonstrated maximum gel strengths i.e. 743 ± 15.28 and 783.33 ± 15.28 g·cm(-2) respectively. Various environmental parameters influenced the chemical composition of K. alvarezii, and these parameters demonstrated seasonal fluctuations. Moreover, based on the nutritional composition obtained, it could be stated that this seaweed has great scope to be incorporated into several food products as an excellent nutritional supplement, or as a value additive in animal or pet food.

Multiscale spatial and small-scale temporal variation in the composition of Riverine fish communities.

PubMed

Growns, Ivor; Astles, Karen; Gehrke, Peter

2006-03-01

We studied the multiscale (sites, river reaches and rivers) and short-term temporal (monthly) variability in a freshwater fish assemblage. We found that small-scale spatial variation and short-term temporal variability significantly influenced fish community structure in the Macquarie and Namoi Rivers. However, larger scale spatial differences between rivers were the largest source of variation in the data. The interaction between temporal change and spatial variation in fish community structure, whilst statistically significant, was smaller than the variation between rivers. This suggests that although the fish communities within each river changed between sampling occasions, the underlying differences between rivers were maintained. In contrast, the strongest interaction between temporal and spatial effects occurred at the smallest spatial scale, at the level of individual sites. This means whilst the composition of the fish assemblage at a given site may fluctuate, the magnitude of these changes is unlikely to affect larger scale differences between reaches within rivers or between rivers. These results suggest that sampling at any time within a single season will be sufficient to show spatial differences that occur over large spatial scales, such as comparisons between rivers or between biogeographical regions.

Energetic particle composition variations during the March 1991 events measured with the Ulysses EPAC instrument

NASA Technical Reports Server (NTRS)

Krupp, N.; Keppler, E.; Fraenz, M.; Korth, A.; Witte, M.; Moussas, X.; Blake, J. B.; Naidu, K.; Quenby, J. J.; Woch, J.

1992-01-01

Energetic particle measurements are reported which were obtained with the EPAC instrument on board the Ulysses spacecraft during March 1991 when a series of important flares occurred at the sun. The time interval March 22 through March 29 is studied in three periods with different ion compositions. At a quasi-perpendicular shock on March 23, shock-drift acceleration of protons, helium and electrons was observed. Thirteen hours after this shock the energetic ion composition changed dramatically by almost two orders of magnitude, signaling the arrival of a coronal mass ejection or driver gas. This driver gas was still present at the spacecraft when a second quasi-perpendicular shock passed the spacecraft. The ratio Fe/O increased from 0.6 to 1.0 indicative of a connection to solar particles for about six hours after the second shock. The second shock did not accelerate ions as well and electrons not at all. Six hours after this shock the same oxygen and ion composition was observed as before, indicating that the second shock did not alter the energetic ion composition. A third ion composition was observed before the driver gas disappeared which was significantly different from those observed before the first and between the two shocks.

Variation in chemical composition and physical characteristics of cereal grains from different genotypes.

PubMed

Rodehutscord, Markus; Rückert, Christine; Maurer, Hans Peter; Schenkel, Hans; Schipprack, Wolfgang; Bach Knudsen, Knud Erik; Schollenberger, Margit; Laux, Meike; Eklund, Meike; Siegert, Wolfgang; Mosenthin, Rainer

2016-01-01

Genotypes of cereal grains, including winter barley (n = 21), maize (n = 27), oats (n = 14), winter rye (n = 22), winter triticale (n = 21) and winter wheat (n = 29), were assayed for their chemical composition and physical characteristics as part of the collaborative research project referred to as GrainUp. Genotypes of one grain species were grown on the same site, except maize. In general, concentrations of proximate nutrients were not largely different from feed tables. The coefficient of variation (CV) for the ether extract concentration of maize was high because the data pool comprised speciality maize bred for its high oil content. A subset of 8 barley, 20 rye, 20 triticale and 20 wheat samples was analysed to differ significantly in several carbohydrate fractions. Gross energy concentration of cereal grains could be predicted from proximate nutrient concentration with good accuracy. The mean lysine concentration of protein was the highest in oats (4.2 g/16 g N) and the lowest in wheat (2.7 g/16 g N). Significant differences were also detected in the concentrations of macro elements as well as iron, manganese, zinc and copper. Concentrations of arsenic, cadmium and lead were below the limit of detection. The concentration of lower inositol phosphates was low, but some inositol pentaphosphates were detected in all grains. In barley, relatively high inositol tetraphosphate concentration also was found. Intrinsic phytase activity was the highest in rye, followed by triticale, wheat, barley and maize, and it was not detectable in oats. Substantial differences were seen in the thousand seed weight, test weight, falling number and extract viscoelasticity characteristics. The study is a comprehensive overview of the composition of different cereal grain genotypes when grown on the same location. The relevance of the variation in composition for digestibility in different animal species will be subject of other communications.

Lateral variation in upper mantle temperature and composition beneath mid-ocean ridges inferred from shear-wave propagation, geoid, and bathymetry. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Sheehan, Anne Francis

1991-01-01

Resolution of both the extent and mechanism of lateral heterogeneity in the upper mantle constraints the nature and scales of mantle convection. Oceanic regions are of particular interest as they are likely to provide the closest glimpse at the patterns of temperature anomalies and convective flow in the upper mantle because of their young age and simple crustal structure relative to continental regions. Lateral variations were determined in the seismic velocity and attenuation structure of the lithosphere and astenosphere beneath the oceans, and these seismological observations were combined with the data and theory of geoid and bathymetry anomalies in order to test and improve current models for seafloor spreading and mantle convection. Variations were determined in mantle properties on a scale of about 1000 km, comparable to the thickness of the upper mantle. Seismic velocity, geoid, and bathymetry anomalies are all sensitive to variations in upper mantle density, and inversions were formulated to combine quantitatively these different data and to search for a common origin. Variations in mantle density can be either of thermal or compositional origin and are related to mantle convection or differentiation.

Inter- and intra-observer variation in soft-tissue sarcoma target definition.

PubMed

Roberge, D; Skamene, T; Turcotte, R E; Powell, T; Saran, N; Freeman, C

2011-08-01

To evaluate inter- and intra-observer variability in gross tumor volume definition for adult limb/trunk soft tissue sarcomas. Imaging studies of 15 patients previously treated with preoperative radiation were used in this study. Five physicians (radiation oncologists, orthopedic surgeons and a musculoskeletal radiologist) were asked to contour each of the 15 tumors on T1-weighted, gadolinium-enhanced magnetic resonance images. These contours were drawn twice by each physician. The volume and center of mass coordinates for each gross tumor volume were extracted and a Boolean analysis was performed to measure the degree of volume overlap. The median standard deviation in gross tumor volumes across observers was 6.1% of the average volume (range: 1.8%-24.9%). There was remarkably little variation in the 3D position of the gross tumor volume center of mass. For the 15 patients, the standard deviation of the 3D distance between centers of mass ranged from 0.06 mm to 1.7 mm (median 0.1mm). Boolean analysis demonstrated that 53% to 90% of the gross tumor volume was common to all observers (median overlap: 79%). The standard deviation in gross tumor volumes on repeat contouring was 4.8% (range: 0.1-14.4%) with a standard deviation change in the position of the center of mass of 0.4mm (range: 0mm-2.6mm) and a median overlap of 93% (range: 73%-98%). Although significant inter-observer differences were seen in gross tumor volume definition of adult soft-tissue sarcoma, the center of mass of these volumes was remarkably consistent. Variations in volume definition did not correlate with tumor size. Radiation oncologists should not hesitate to review their contours with a colleague (surgeon, radiologist or fellow radiation oncologist) to ensure that they are not outliers in sarcoma gross tumor volume definition. Protocols should take into account variations in volume definition when considering tighter clinical target volumes. Copyright © 2011 Société française de radioth

Meteorological control of lower stratospheric minor species variations - An observational example

NASA Technical Reports Server (NTRS)

Alyea, F. N.; Cunnold, D. M.

1978-01-01

Lower stratospheric air trajectories entering the region over Alaska at the approximately 125 mb level during late May, 1975 indicate a substantial shift in the geographical source regions for the air masses present during that time. This shift coincides with an approximately 25% decrease in the observed halocarbon mixing ratios at the 125 mb level as determined from a daily sequence of halocarbon profiles. Since the halocarbon species measured are essentially chemically inactive at this level, the observed variation is linked to the changing meteorological pattern.

Heat flux variations over sea ice observed at the coastal area of the Sejong Station, Antarctica

NASA Astrophysics Data System (ADS)

Park, Sang-Jong; Choi, Tae-Jin; Kim, Seong-Joong

2013-08-01

This study presents variations of sensible heat flux and latent heat flux over sea ice observed in 2011 from the 10-m flux tower located at the coast of the Sejong Station on King George Island, Antarctica. A period from July to September was selected as a sea ice period based on daily record of sea state and hourly photos looking at the Marian Cove in front of the Sejong Station. For the sea ice period, mean sensible heat flux is about -11 Wm-2, latent heat flux is about +2 W m-2, net radiation is -12 W m-2, and residual energy is -3 W m-2 with clear diurnal variations. Estimated mean values of surface exchange coefficients for momentum, heat and moisture are 5.15 × 10-3, 1.19 × 10-3, and 1.87 × 10-3, respectively. The observed exchange coefficients of heat shows clear diurnal variations while those of momentum and moisture do not show diurnal variation. The parameterized exchange coefficients of heat and moisture produces heat fluxes which compare well with the observed diurnal variations of heat fluxes.

The comparison of SRs' variation affected by solar events observed in America and in China

NASA Astrophysics Data System (ADS)

Yu, H.; Williams, E.

2017-12-01

Schumann Resonances(SRs) are the electromagnetic resonance wave propagating in the earth-ionosphere cavity. Its characteristic of propagation are modified by the variation of ionosphere. So SRs can be the tools of monitoring the ionosphere which is often perturbed by solar events, x-ray emission and some other space-weather events (Roldugin et.al., 2004, De et al., 2010; Satori et.al., 2015). In present work, the amplitude and intrinsic frequencies of SRs observed at RID station in America and YSH station in China are compared. The variation of SRs during the solar flare on Feb. 15, 2011 are analyzed. Two-Dimensional Telegraph Equation(TDTE) method is used to simulate the perturbation of ionosphere by solar proton events. From the simulation and observation, the asymmetric construction of ionoshphere which is perturbed by the solar event will affect the amplitudes and frequencies of SRs. Due to the interfere influence of forward and backward propagation of electromagnetic field, the SR amplitude on different station will present different variation. The distance among the lightning source, observer and perturbed area will produce the different variation of amplitude and frequency for different station' SR.

ERP-Variations on Time Scales Between Hours and Months Derived From GNSS Observations

NASA Astrophysics Data System (ADS)

Weber, R.; Englich, S.; Mendes Cerveira, P.

2007-05-01

Current observations gained by the space geodetic techniques, especially VLBI, GPS and SLR, allow for the determination of Earth Rotation Parameters (ERPs - polar motion, UT1/LOD) with unprecedented accuracy and temporal resolution. This presentation focuses on contributions to the ERP recovery provided by satellite navigation systems (primarily GPS). The IGS (International GNSS Service), for example, currently provides daily polar motion with an accuracy of less than 0.1mas and LOD estimates with an accuracy of a few microseconds. To study more rapid variations in polar motion and LOD we established in a first step a high resolution (hourly resolution) ERP-time series from GPS observation data of the IGS network covering the year 2005. The calculations were carried out by means of the Bernese GPS Software V5.0 considering observations from a subset of 113 fairly stable stations out of the IGS05 reference frame sites. From these ERP time series the amplitudes of the major diurnal and semidiurnal variations caused by ocean tides are estimated. After correcting the series for ocean tides the remaining geodetic observed excitation is compared with variations of atmospheric excitation (AAM). To study the sensitivity of the estimates with respect to the applied mapping function we applied both the widely used NMF (Niell Mapping Function) and the VMF1 (Vienna Mapping Function 1). In addition, based on computations covering two months in 2005, the potential improvement due to the use of additional GLONASS data will be discussed.

Temporal variations of methane concentration and isotopic composition in groundwater of the St. Lawrence Lowlands, eastern Canada

NASA Astrophysics Data System (ADS)

Rivard, Christine; Bordeleau, Geneviève; Lavoie, Denis; Lefebvre, René; Malet, Xavier

2018-03-01

Dissolved methane concentrations in shallow groundwater are known to vary both spatially and temporally. The extent of these variations is poorly documented although this knowledge is critical for distinguishing natural fluctuations from anthropogenic impacts stemming from oil and gas activities. This issue was addressed as part of a groundwater research project aiming to assess the risk of shale gas development for groundwater quality over a 500-km2 area in the St. Lawrence Lowlands (Quebec, Canada). A specific study was carried out to define the natural variability of methane concentrations and carbon and hydrogen isotope ratios in groundwater, as dissolved methane is naturally ubiquitous in aquifers of this area. Monitoring was carried out over a period of up to 2.5 years in seven monitoring wells. Results showed that for a given well, using the same sampling depth and technique, methane concentrations can vary over time from 2.5 to 6 times relative to the lowest recorded value. Methane isotopic composition, which is a useful tool to distinguish gas origin, was found to be stable for most wells, but varied significantly over time in the two wells where methane concentrations are the lowest. The use of concentration ratios, as well as isotopic composition of methane and dissolved inorganic carbon (DIC), helped unravel the processes responsible for these variations. This study indicates that both methane concentrations and isotopic composition, as well as DIC isotopes, should be regularly monitored over at least 1 year to establish their potential natural variations prior to hydrocarbon development.

The composition of M-type asteroids: Synthesis of spectroscopic and radar observations

NASA Astrophysics Data System (ADS)

Neeley, J. R.; Ockert-Bell, M. E.; Clark, B. E.; Shepard, M. K.; Cloutis, E. A.; Fornasier, S.; Bus, S. J.

2011-10-01

This work updates our and expands our long term radar-driven observational campaign of 27 main-belt asteroids (MBAs) focused on Bus-DeMeo Xc- and Xk-type objects (Tholen X and M class asteroids) using the Arecibo radar and NASA Infrared Telescope Facilities (IRTF). Seventeen of our targets were near-simultaneously observed with radar and those observations are described in companion paper (Shepard et al., 2010). We utilized visible wavelength for a more complete compositional analysis of our targets. Compositional evidence is derived from our target asteroid spectra using three different methods: 1) a χ2 search for spectral matches in the RELAB database, 2) parametric comparisons with meteorites and 3) linear discriminant analysis. This paper synthesizes the results of the RELAB search, parametric comparisons, and linear discriminant analysis with compositional suggestions based on radar observations. We find that for six of seventeen targets with radar data, our spectral results are consistent with their radar analog (16 Psyche, 21 Lutetia, 69 Hesperia, 135 Hertha, 216 Kleopatra, and 497 Iva). For twenty out of twenty-seven objects our statistical comparisons with RELAB meteorites result in consistent analog identification, providing a degree of confidence in our parametric methods.

GLAG theory for superconducting property variations with A15 composition in Nb3Sn wires.

PubMed

Li, Yingxu; Gao, Yuanwen

2017-04-25

We present a model for the variation of the upper critical field H c2 with Sn content in A15-type Nb-Sn wires, within the Ginzburg-Landau-Abrikosov-Gor'kov (GLAG) theory frame. H c2 at the vicinity of the critical temperature T c is related quantitatively to the electrical resistivity ρ, specific heat capacity coefficient γ and T c . H c2 versus tin content is theoretically formulated within the GLAG theory, and generally reproduces the experiment results. As Sn content gradually approaches the stoichiometry, A15-type Nb-Sn undergoes a transition from the dirty limit to clean limit, split by the phase transformation boundary. The H-T phase boundary and pinning force show different behaviors in the cubic and tetragonal phase. We dipict the dependence of the composition gradient on the superconducting properties variation in the A15 layer, as well as the curved tail at vicinity of H c2 in the Kramer plot of the Nb 3 Sn wire. This helps understanding of the inhomogeneous-composition inducing discrepancy between the results by the state-of-art scaling laws and experiments.

Explaining variation in tropical plant community composition: influence of environmental and spatial data quality.

PubMed

Jones, Mirkka M; Tuomisto, Hanna; Borcard, Daniel; Legendre, Pierre; Clark, David B; Olivas, Paulo C

2008-03-01

The degree to which variation in plant community composition (beta-diversity) is predictable from environmental variation, relative to other spatial processes, is of considerable current interest. We addressed this question in Costa Rican rain forest pteridophytes (1,045 plots, 127 species). We also tested the effect of data quality on the results, which has largely been overlooked in earlier studies. To do so, we compared two alternative spatial models [polynomial vs. principal coordinates of neighbour matrices (PCNM)] and ten alternative environmental models (all available environmental variables vs. four subsets, and including their polynomials vs. not). Of the environmental data types, soil chemistry contributed most to explaining pteridophyte community variation, followed in decreasing order of contribution by topography, soil type and forest structure. Environmentally explained variation increased moderately when polynomials of the environmental variables were included. Spatially explained variation increased substantially when the multi-scale PCNM spatial model was used instead of the traditional, broad-scale polynomial spatial model. The best model combination (PCNM spatial model and full environmental model including polynomials) explained 32% of pteridophyte community variation, after correcting for the number of sampling sites and explanatory variables. Overall evidence for environmental control of beta-diversity was strong, and the main floristic gradients detected were correlated with environmental variation at all scales encompassed by the study (c. 100-2,000 m). Depending on model choice, however, total explained variation differed more than fourfold, and the apparent relative importance of space and environment could be reversed. Therefore, we advocate a broader recognition of the impacts that data quality has on analysis results. A general understanding of the relative contributions of spatial and environmental processes to species distributions

Observations of Mercury's Surface-Bounded Exosphere from Orbit: Results from the Mercury Atmospheric and Surface Composition Spectrometer aboard the MESSENGER Spacecraft

NASA Astrophysics Data System (ADS)

McClintock, W. E.; Burger, M. H.; Cassidy, T. A.; Killen, R. M.; Merkel, A. W.; Sarantos, M.; Solomon, S. C.; Vervack, R. J., Jr.

2015-12-01

The Mercury Atmospheric and Surface Composition Spectrometer (MASCS), on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft, conducted orbital observations of Mercury's dayside and nightside exosphere from 29 March 2011 to the end of the mission on 30 April 2015. Over slightly more than four Earth-years, MASCS measured emission profiles versus altitude for calcium (Ca), sodium (Na), and magnesium (Mg) at a daily cadence. These species exhibit different spatial distributions, suggesting distinct source processes. MASCS observed seasonal variations in all three species that are remarkably repeatable from one Mercury year to the next, and did so consistently during the entire 17-Mercury-year duration of the orbital phase of the mission. Whereas MASCS has characterized the seasonal variation, it has provided, at best, only weak evidence for the episodic behavior observed in ground-based studies of Na. Joint analyses of MASCS observations and surface precipitation patterns for energetic particles inferred from observations by the Energetic Particle Spectrometer (EPS) and the Fast Imaging Plasma Spectrometer (FIPS) on MESSENGER have not yielded clear correlations. This lack of correlation may be due in part to the MASCS observational geometries. MASCS has conducted a number of searches for other, weakly emitting species. Hydrogen data from the orbital phase are consistent with profiles observed during MESSENGER's flybys of Mercury. Oxygen detections have proven elusive, and the previously reported observation with a brightness of 4 R may only be an upper limit. Ongoing analysis of weak species data suggests that additional species are present.

Human fecal flora: variation in bacterial composition within individuals and a possible effect of emotional stress.

PubMed Central

Holdeman, L V; Good, I J; Moore, W E

1976-01-01

Data are presented on the distribution of 101 bacterial species and subspecies among 1,442 isolates from 25 fecal specimens from three men on: (i) their normal diet and normal living conditions, (ii) normal living conditions but eating the controlled metabolic diet designed for use in the Skylab simulation and missions, and (iii) the Skylab diet in simulated Skylab (isolation) conditions. These bacteria represent the most numerous kinds in the fecal flora. Analyses of the kinds of bacteria from each astronaut during the 5-month period showed more variation in the composition of the flora among the individual astronauts than among the eight or nine samples from each person. This observation indicates that the variations in fecal flora reported previously, but based on the study of only one specimen from each person, more certainly reflect real differences (and not daily variation) in the types of bacteria maintained by individual people. The proportions of the predominant fecal species in the astronauts were similar to those reported earlier from a Japanese-Hawaiian population and were generally insensitive to changes from the normal North American diet to the Skylab diet; only two of the most common species were affected by changes in diet. However, one of the predominant species (Bacteroides fragilis subsp. thetaiotaomicron) appeared to be affected during confinement of the men in the Skylab test chamber. Evidence is presented suggesting that an anger stress situation may have been responsible for the increase of this species simultaneously in all of the subjects studied. Phenotypic characteristics of some of the less common isolates are given. The statistical analyses used in interpretation of the results are discussed. PMID:938032

Land cover variation and West Nile virus prevalence: Patterns, processes, and implications for disease control

USGS Publications Warehouse

Ezenwa, V.O.; Milheim, L.E.; Coffey, M.F.; Godsey, M.S.; King, R.J.; Guptill, S.C.

2007-01-01

Identifying links between environmental variables and infectious disease risk is essential to understanding how human-induced environmental changes will effect the dynamics of human and wildlife diseases. Although land cover change has often been tied to spatial variation in disease occurrence, the underlying factors driving the correlations are often unknown, limiting the applicability of these results for disease prevention and control. In this study, we described associations between land cover composition and West Nile virus (WNV) infection prevalence, and investigated three potential processes accounting for observed patterns: (1) variation in vector density; (2) variation in amplification host abundance; and (3) variation in host community composition. Interestingly, we found that WNV infection rates among Culex mosquitoes declined with increasing wetland cover, but wetland area was not significantly associated with either vector density or amplification host abundance. By contrast, wetland area was strongly correlated with host community composition, and model comparisons suggested that this factor accounted, at least partially, for the observed effect of wetland area on WNV infection risk. Our results suggest that preserving large wetland areas, and by extension, intact wetland bird communities, may represent a valuable ecosystem-based approach for controlling WNV outbreaks. ?? Mary Ann Liebert, Inc.

Hydration of marginal basins and compositional variations within the continental lithospheric mantle inferred from a new global model of shear and compressional velocity

NASA Astrophysics Data System (ADS)

Tesoniero, Andrea; Auer, Ludwig; Boschi, Lapo; Cammarano, Fabio

2015-11-01

We present a new global model of shear and compressional wave speeds for the entire mantle, partly based on the data set employed for the shear velocity model savani. We invert Rayleigh and Love surface waves up to the sixth overtone in combination with major P and S body wave phases. Mineral physics data on the isotropic δlnVS/δlnVP ratio are taken into account in the form of a regularization constraint. The relationship between VP and VS that we observe in the top 300 km of the mantle has important thermochemical implications. Back-arc basins in the Western Pacific are characterized by large VP/VS and not extremely low VS at ˜150 km depth, consistently with presence of water. Most pronounced anomalies are located in the Sea of Japan, in the back-arc region of the Philippine Sea, and in the South China Sea. Our results indicate the effectiveness of slab-related processes to hydrate the mantle and suggest an important role of Pacific plate subduction also for the evolution of the South China Sea. We detect lateral variations in composition within the continental lithospheric mantle. Regions that have been subjected to rifting, collisions, and flood basalt events are underlain by relatively large VP/VS ratio compared to undeformed Precambrian regions, consistently with a lower degree of chemical depletion. Compositional variations are also observed in deep lithosphere. At ˜200 km depth, mantle beneath Australia and African cratons has comparable positive VS anomalies with other continental regions, but VP is ˜1% higher.

Influence of the balance of the intertropical front on seasonal variations of the isotopic composition in rainfall at Kisiba Masoko (Rungwe Volcanic Province, SW, Tanzania).

PubMed

Nivet, Fantine; Bergonzini, Laurent; Mathé, Pierre-Etienne; Noret, Aurélie; Monvoisin, Gaël; Majule, Amos; Williamson, David

2018-08-01

Tropical rainfall isotopic composition results from complex processes. The climatological and environmental variability in East Africa increases this complexity. Long rainfall isotope datasets are needed to fill the lack of observations in this region. At Kisiba Masoko, Tanzania, rainfall and rain isotopic composition have been monitored during 6 years. Mean year profiles allow to analyse the seasonal variations. The mean annual rainfall is 2099 mm with a rain-weighted mean composition of -3.2 ‰ for δ 18 O and -11.7 ‰ for δ 2 H. The results are consistent with available data although they present their own specificity. Thus, if the local meteoric water line is δ 2 H = 8.6 δ 18 O + 14.8, two seasonal lines are observed. The seasonality of the isotopic composition in rain and deuterium excess has been compared with precipitating air masses backtracking trajectories to characterize a simple scheme of vapour histories. The three major oceanic sources have two moisture signatures with their own trajectory histories: one originated from the tropical Indian Ocean at the beginning of the rainy season and one from the Austral Ocean at its end. The presented isotopic seasonality depends on the balance of the intertropical front and provides a useful dataset to improve the knowledge about local processes.

Seasonal Variations of the Antioxidant Composition in Ground Bamboo Sasa argenteastriatus Leaves

PubMed Central

Ni, Qinxue; Xu, Guangzhi; Wang, Zhiqiang; Gao, Qianxin; Wang, Shu; Zhang, Youzuo

2012-01-01

Sasa argenteastriatus, with abundant active compounds and high antioxidant activity in leaves, is a new leafy bamboo grove suitable for exploitation. To utilize it more effectively and scientifically, we investigate the seasonal variations of antioxidant composition in its leaves and antioxidant activity. The leaves of Sasa argenteastriatus were collected on the 5th day of each month in three same-sized sample plots from May 2009 to May 2011. The total flavonoids (TF): phenolics (TP) and triterpenoid (TT) of bamboo leaves were extracted and the contents analyzed by UV-spectrophotometer. Our data showed that all exhibited variations with the changing seasons, with the highest levels appearing in November to March. Antioxidant activity was measured using DPPH and FRAP methods. The highest antioxidant activity appeared in December with the lowest in May. Correlation analyses demonstrated that TP and TF exhibited high correlation with bamboo antioxidant activity. Eight bamboo characteristic compounds (orientin, isoorientin, vitexin, homovitexin and p-coumaric acid, chlorogenic acid, caffeic acid, ferulic acid) were determined by RP-HPLC synchronously. We found that chlorogenic acid, isoorientin and vitexin are the main compounds in Sasa argenteastriatus leaves and the content of isovitexin and chlorogenic acid showed a similar seasonal variation with the TF, TP and TT. Our results suggested that the optimum season for harvesting Sasa argenteastriatus leaves is between autumn and winter. PMID:22408451

Spatial Variations of DOM Compositions in the River with Multi-functional Weir

NASA Astrophysics Data System (ADS)

Yoon, S. M.; Choi, J. H.

2017-12-01

With the global trend to construct artificial impoundments over the last decades, there was a Large River Restoration Project conducted in South Korea from 2010 to 2011. The project included enlargement of river channel capacity and construction of multi-functional weirs, which can alter the hydrological flow of the river and cause spatial variations of water quality indicators, especially DOM (Dissolved Organic Matter) compositions. In order to analyze the spatial variations of organic matter, water samples were collected longitudinally (5 points upstream from the weir), horizontally (left, center, right at each point) and vertically (1m interval at each point). The specific UV-visible absorbance (SUVA) and fluorescence excitation-emission matrices (EEMs) have been used as rapid and non-destructive analytical methods for DOM compositions. In addition, parallel factor analysis (PARAFAC) has adopted for extracting a set of representative fluorescence components from EEMs. It was assumed that autochthonous DOM would be dominant near the weir due to the stagnation of hydrological flow. However, the results showed that the values of fluorescence index (FI) were 1.29-1.47, less than 2, indicating DOM of allochthonous origin dominated in the water near the weir. PARAFAC analysis also showed the peak at 450 nm of emission and < 250 nm of excitation which represented the humic substances group with terrestrial origins. There was no significant difference in the values of Biological index (BIX), however, values of humification index (HIX) spatially increased toward the weir. From the results of the water sample analysis, the river with multi-functional weir is influenced by the allochthonous DOM instead of autochthonous DOM and seems to accumulate humic substances near the weir.

Defining microbial community composition and seasonal variation in a sewage treatment plant in India using a down-flow hanging sponge reactor.

PubMed

Nomoto, Naoki; Hatamoto, Masashi; Hirakata, Yuga; Ali, Muntjeer; Jayaswal, Komal; Iguchi, Akinori; Okubo, Tsutomu; Takahashi, Masanobu; Kubota, Kengo; Tagawa, Tadashi; Uemura, Shigeki; Yamaguchi, Takashi; Harada, Hideki

2018-05-01

The characteristics of the microbial community in a practical-scale down-flow hanging sponge (DHS) reactor, high in organic matter and sulfate ion concentration, and the seasonal variation of the microbial community composition were investigated. Microorganisms related to sulfur oxidation and reduction (2-27%), as well as Leucobacter (7.50%), were abundant in the reactor. Anaerobic bacteria (27-38% in the first layer) were also in abundance and were found to contribute to the removal of organic matter from the sewage in the reactor. By comparing the Simpson index, the abundance-based coverage estimator (ACE) index, and the species composition of the microbial community across seasons (summer/dry, summer/rainy, autumn/dry, and winter/dry), the microbial community was found to change in composition only during the winter season. In addition to the estimation of seasonal variation, the difference in the microbial community composition along the axes of the DHS reactor was investigated for the first time. Although the abundance of each bacterial species differed along both axes of the reactor, the change of the community composition in the reactor was found to be greater along the vertical axis than the horizontal axis of the DHS reactor.

Implications of the Observed Mesoscale Variations of Clouds for Earth's Radiation Budget

NASA Technical Reports Server (NTRS)

Rossow, William B.; Delo, Carl; Cairns, Brian; Hansen, James E. (Technical Monitor)

2001-01-01

The effect of small-spatial-scale cloud variations on radiative transfer in cloudy atmospheres currently receives a lot of research attention, but the available studies are not very clear about which spatial scales are important and report a very large range of estimates of the magnitude of the effects. Also, there have been no systematic investigations of how to measure and represent these cloud variations. We exploit the cloud climatology produced by the International Satellite Cloud Climatology Project (ISCCP) to: (1) define and test different methods of representing cloud variation statistics, (2) investigate the range of spatial scales that should be included, (3) characterize cloud variations over a range of space and time scales covering mesoscale (30 - 300 km, 3-12 hr) into part of the lower part of the synoptic scale (300 - 3000 km, 1-30 days), (4) obtain a climatology of the optical thickness, emissivity and cloud top temperature variability of clouds that can be used in weather and climate GCMS, together with the parameterization proposed by Cairns et al. (1999), to account for the effects of small-scale cloud variations on radiative fluxes, and (5) evaluate the effect of observed cloud variations on Earth's radiation budget. These results lead to the formulation of a revised conceptual model of clouds for use in radiative transfer calculations in GCMS. The complete variability climatology can be obtained from the ISCCP Web site at http://isccp.giss.nasa.gov.

Variations in abundance, diversity and community composition of airborne fungi in swine houses across seasons

PubMed Central

Kumari, Priyanka; Woo, Cheolwoon; Yamamoto, Naomichi; Choi, Hong-Lim

2016-01-01

We examined the abundance, diversity and community composition of airborne fungi in swine houses during winter and summer seasons by using quantitative PCR and Illumina HiSeq sequencing of ITS1 region. The abundance of airborne fungi varied significantly only between seasons, while fungal diversity varied significantly both within and between seasons, with both abundance and diversity peaked in winter. The fungal OTU composition was largely structured by the swine house unit and season as well as by their interactions. Of the measured microclimate variables, relative humidity, particulate matters (PMs), ammonia, and stocking density were significantly correlated with fungal OTU composition. The variation in beta diversity was higher within swine houses during summer, which indicates that the airborne fungal community composition was more heterogeneous in summer compared to winter. We also identified several potential allergen/pathogen related fungal genera in swine houses. The total relative abundance of potential allergen/pathogen related fungal genera varied between swine houses in both seasons, and showed positive correlation with PM2.5. Overall, our findings show that the abundance, diversity and composition of airborne fungi are highly variable in swine houses and to a large extent structured by indoor microclimate variables of swine houses. PMID:27892507

Variations in abundance, diversity and community composition of airborne fungi in swine houses across seasons

NASA Astrophysics Data System (ADS)

Kumari, Priyanka; Woo, Cheolwoon; Yamamoto, Naomichi; Choi, Hong-Lim

2016-11-01

We examined the abundance, diversity and community composition of airborne fungi in swine houses during winter and summer seasons by using quantitative PCR and Illumina HiSeq sequencing of ITS1 region. The abundance of airborne fungi varied significantly only between seasons, while fungal diversity varied significantly both within and between seasons, with both abundance and diversity peaked in winter. The fungal OTU composition was largely structured by the swine house unit and season as well as by their interactions. Of the measured microclimate variables, relative humidity, particulate matters (PMs), ammonia, and stocking density were significantly correlated with fungal OTU composition. The variation in beta diversity was higher within swine houses during summer, which indicates that the airborne fungal community composition was more heterogeneous in summer compared to winter. We also identified several potential allergen/pathogen related fungal genera in swine houses. The total relative abundance of potential allergen/pathogen related fungal genera varied between swine houses in both seasons, and showed positive correlation with PM2.5. Overall, our findings show that the abundance, diversity and composition of airborne fungi are highly variable in swine houses and to a large extent structured by indoor microclimate variables of swine houses.

Surface compositional variations of Mo-47Re alloy as a function of temperature

NASA Technical Reports Server (NTRS)

Hoekje, S. J.; Outlaw, R. A.; Sankaran, S. N.

1993-01-01

Molybdenum-rhenium alloys are candidate materials for the National Aero-Space Plane (NASP) as well as for other applications in generic hypersonics. These materials are expected to be subjected to high-temperature (above 1200 C) casual hydrogen (below 50 torr), which could potentially degrade the material strength. Since the uptake of hydrogen may be controlled by the contaminant surface barriers, a study of Mo-47Re was conducted to examine the variations in surface composition as a function of temperature from 25 C to 1000 C. Pure molybdenum and rhenium were also examined and the results compared with those for the alloy. The analytical techniques employed were Auger electron spectroscopy, electron energy loss spectroscopy, ion scattering spectroscopy, and x ray photoelectron spectroscopy. The native surface was rich in metallic oxides that disappeared at elevated temperatures. As the temperature increased, the carbon and oxygen disappeared by 800 C and the surface was subsequently populated by the segregation of silicon, presumably from the grain boundaries. The alloy readily chemisorbed oxygen, which disappeared with heating. The disappearance temperature progressively increased for successive dosings. When the alloy was exposed to 800 torr of hydrogen at 900 C for 1 hour, no hydrogen interaction was observed.

Genetic and environmental factors contribute to variation in cell wall composition in mature desi chickpea (Cicer arietinum L.) cotyledons.

PubMed

Wood, Jennifer A; Tan, Hwei-Ting; Collins, Helen M; Yap, Kuok; Khor, Shi Fang; Lim, Wai Li; Xing, Xiaohui; Bulone, Vincent; Burton, Rachel A; Fincher, Geoffrey B; Tucker, Matthew R

2018-03-13

Chickpea (Cicer arietinum L.) is an important nutritionally rich legume crop that is consumed worldwide. Prior to cooking, desi chickpea seeds are most often dehulled and cleaved to release the split cotyledons, referred to as dhal. Compositional variation between desi genotypes has a significant impact on nutritional quality and downstream processing, and this has been investigated mainly in terms of starch and protein content. Studies in pulses such as bean and lupin have also implicated cell wall polysaccharides in cooking time variation, but the underlying relationship between desi chickpea cotyledon composition and cooking performance remains unclear. Here, we utilized a variety of chemical and immunohistological assays to examine details of polysaccharide composition, structure, abundance, and location within the desi chickpea cotyledon. Pectic polysaccharides were the most abundant cell wall components, and differences in monosaccharide and glycosidic linkage content suggest both environmental and genetic factors contribute to cotyledon composition. Genotype-specific differences were identified in arabinan structure, pectin methylesterification, and calcium-mediated pectin dimerization. These differences were replicated in distinct field sites and suggest a potentially important role for cell wall polysaccharides and their underlying regulatory machinery in the control of cooking time in chickpea. © 2018 The Authors. Plant, Cell & Environment Published by John Wiley & Sons Ltd.

Lithospheric thickness controlled compositional variations in potassic basalts of Northeast China by melt-rock interactions

NASA Astrophysics Data System (ADS)

Liu, Jian-Qiang; Chen, Li-Hui; Zeng, Gang; Wang, Xiao-Jun; Zhong, Yuan; Yu, Xun

2016-03-01

Melt-rock interaction is a common mantle process; however, it remains unclear how this process affects the composition of potassic basalt. Here we present a case study to highlight the link between compositional variations in the potassic basalts and melt-rock interaction in cold lithosphere. Cenozoic potassic basalts in Northeast China are strongly enriched in incompatible elements and show EM1-type Sr-Nd-Pb isotopes, suggesting an enriched mantle source. These rocks show good correlations between 87Sr/86Sr and K2O/Na2O and Rb/Nb. Notably, these ratios decrease with increasing lithospheric thickness, which may reflect melt-lithosphere interaction. Phlogopite precipitated when potassic melts passed through the lithospheric mantle, and K and Rb contents of the residual melts decreased over time. The thicker the lithosphere, the greater the loss of K and Rb from the magma. Therefore, the compositions of potassic basalts were controlled by both their enriched sources and reactions with lithospheric mantle.

On quasi-periodic variations of low-energy cosmic rays observed near earth.

PubMed

Kudela, Karel; Langer, Ronald

2015-06-01

Cosmic ray (CR) may partially, especially at high altitudes, contribute to the dosimetric characteristics. Along with irregular CR variations as Forbush decreases and solar particle events are, the quasi-periodic variations may be of some relevance too. A very short review (with references to original papers) of the present knowledge of various types of such variations is presented, namely (i) diurnal wave, (ii) ~27 d variability due to the solar rotation, (iii) Rieger-type periodicity, and (iv) quasi-biennial oscillations as well as waves on longer time scales related to solar activity and to polarity of magnetic field of the Sun. Variability is illustrated in measurements of secondary CR on the ground including the high-altitude observations at Lomnický štít. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

UHECR mass composition measurement at Telescope Array via stereoscopic observation

NASA Astrophysics Data System (ADS)

Stroman, Thomas; Telescope Array Collaboration

2015-04-01

The masses of primary ultra-high-energy cosmic-ray (UHECR) nuclei cannot be measured directly on an individual basis, but constraints on the chemical composition can be inferred from the distributions of observable properties. The atmospheric slant depth at which a UHECR-induced extensive air shower reaches its maximum number of particles, Xmax, is particularly sensitive to the mass of the incident nucleus, occurring earlier in the shower's longitudinal development for heavier nuclei at a given energy. The Telescope Array in west-central Utah, the northern hemisphere's largest UHECR detector, is equipped for accurate Xmax and energy measurements via stereoscopic fluorescence observation. Using data from seven years of operation, we will present Xmax distributions at several energies E >10 18 . 2eV , and compare them to distributions predicted by detailed detector simulations under an assortment of assumed UHECR compositions and high-energy hadronic interaction models.

Age variations in anthropometric and body composition characteristics and undernutrition among female Bathudis: a tribal population of Keonjhar District, Orissa, India.

PubMed

Bose, Kaushik; Chakraborty, Falguni; Bisai, Samiran

2007-09-01

A cross-sectional study of 183 female Bathudis, a tribal population of the Keonjhar District, Orissa, India, was undertaken to investigate age variations in anthropometric and body composition characteristics and nutritional status. The subjects were categorized into three age groups: < or =30 years, 31-50 years, >50 years. Height, weight, circumferences and skinfolds data were collected. Body mass index (BMI) and several body composition variables and indices were derived using standard equations. The results revealed that there existed significant negative age variations for most of the anthropometric and body composition variables and indices. Correlation studies of age with these variables and indices revealed significant negative correlations. Linear regression analyses revealed that for all variables, age had a significant negative impact. Studies on the nutritional status of these women revealed that with increasing age, there was an increase in the frequency of undernutrition. In conclusion, this study demonstrated that among Bathudi women, age was significantly negatively related with anthropometric and body composition variables and indices. Moreover, with increasing age, the level of undernutrition increased.

Influence of Compositional Variations on Floc Size and Strength

NASA Astrophysics Data System (ADS)

Yin, H.; Tan, X.; Reed, A. H.; Furukawa, Y.; Zhang, G.

2010-12-01

Clay-biopolymer micro aggregates or flocs are abundant in waters, including rivers, lakes, and oceans. Owing to their small size and charged surfaces, fine-grained inorganic sediment particles, mainly clays, interact actively with organic substances, such as organic matter and biogenic polymers, to form aggregates or flocs, typically in the size of 10-1000 μm. The flocs in ocean waters are also termed “marine snow”. These flocs are typically porous, tenuous, and soft in nature. During transport in suspension, they may breakdown and decrease in size if the turbulent shear stress exceeds their strength. They may also collide and form larger ones if the shear stress is relatively small. Since flocs of different size and structure settle at different velocities, understanding their strength is also of essential importance for sediment hydrodynamics, transport, and management. Our study focuses on investigating the influence of compositional variations on floc size and strength so that a better understanding of floc dynamics can be achieved. A laser diffraction-based Cilas® particle size and shape analyzer with controllable fluid circulation velocity was employed to conduct floc size measurements and shape imaging, the latter achieved by a high resolution inverted optical microscope, which is also installed with the size analyzer. Totally two clay minerals, kaolinite and illite, were tested as the model inorganic solid skeleton minerals for floc formation, and two biopolymers, anionic xanthan gum and neutral guar gum, were chosen as analogs of naturally occurring organic matter or biopolymers to simulate clay-biopolymer floc formation. Moreover, the concentration of both organic and inorganic phases was varied. The floc breakage or tensile strength was indirectly estimated by the varied fluid flow velocity in the particle size analyzer’s circulation system. For each individual composition, stable flocs were formed by three different fluid circulating velocities

Systematic Relationships Between Lidar Observables and Sizes And Mineral Composition Of Dust Aerosols

NASA Technical Reports Server (NTRS)

Van Diedenhoven, Bastiaan; Stangl, Alexander; Perlwitz, Jan; Fridlind, Ann M.; Chowdhary, Jacek; Cairns, Brian

2015-01-01

The physical and chemical properties of soil dust aerosol particles fundamentally affect their interaction with climate, including shortwave absorption and radiative forcing, nucleation of cloud droplets and ice crystals, heterogeneous formation of sulfates and nitrates on the surface of dust particles, and atmospheric processing of iron into bioavailable forms that increase the productivity of marine phytoplankton. Lidar measurements, such as extinction-to-backscatter, color and depolarization ratios, are frequently used to distinguish between aerosol types with different physical and chemical properties. The chemical composition of aerosol particles determines their complex refractive index, hence affecting their backscattering properties. Here we present a study on how dust aerosol backscattering and depolarization properties at wavelengths of 355, 532 and 1064 nm are related to size and complex refractive index, which varies with the mineral composition of the dust. Dust aerosols are represented by collections of spheroids with a range of prolate and oblate aspect ratios and their optical properties are obtained using T-matrix calculations. We find simple, systematic relationships between lidar observables and the dust size and complex refractive index that may aid the use of space-based or airborne lidars for direct retrieval of dust properties or for the evaluation of chemical transport models using forward simulated lidar variables. In addition, we present first results on the spatial variation of forward-simulated lidar variables based on a dust model that accounts for the atmospheric cycle of eight different mineral types plus internal mixtures of seven mineral types with iron oxides, which was recently implemented in the NASA GISS Earth System ModelE2.

An Overview of OCTAV-UTLS (Observed Composition Trends and Variability in the UTLS), a SPARC Emerging Activity

NASA Astrophysics Data System (ADS)

Petropavlovskikh, I. V.; Manney, G. L.; Hoor, P. M.; Bourassa, A. E.; Braathen, G.; Chang, K. L.; Hegglin, M. I.; Kramarova, N. A.; Kunkel, D.; Lawrence, Z. D.; Leblanc, T.; Livesey, N. J.; Millan Valle, L. F.; Stiller, G. P.; Tegtmeier, S.; Thouret, V.; Voigt, C.; Walker, K. A.

2017-12-01

The distribution of tracers in the upper troposphere and lower stratosphere (UTLS) shows large spatial and temporal variability because of interactions of transport, chemical, and mixing processes near the tropopause, as well as variations in the location of the tropopause itself. This strongly affects quantitative estimates of the impact of radiatively active substances, including ozone and water vapour, on surface temperatures, and complicates diagnosis of dynamical processes such as stratosphere troposphere exchange (STE). The Stratosphere-troposphere Processes And their Role in Climate (SPARC) emerging activity OCTAV-UTLS (Observed Composition Trends and Variability in the UTLS) aims to reduce the uncertainties in trend estimates by accounting for these dynamically induced sources of variability. Achieving these goals by using existing UTLS trace gas observations from aircraft, ground-based, balloon and satellite platforms requires a consistent analysis of these different data with respect to the tropopause or the jets. As a central task for OCTAV-UTLS, we are developing and applying common metrics, calculated using the same reanalysis datasets, to compare UTLS data using geophysically-based coordinate systems including tropopause and upper tropospheric jet relative coordinates. In addition to assessing present day measurement capabilities, OCTAV-UTLS will assess gaps in current geographical / temporal sampling of the UTLS that limit our ability to determine atmospheric composition variability and trends. This talk will provide an overview of the OCTAV-UTLS activity and some examples of initial calculations of geophysically-based coordinates and comparisons of remapped data.

A Multi-Variate Fit to the Chemical Composition of the Cosmic-Ray Spectrum

NASA Astrophysics Data System (ADS)

Eisch, Jonathan

Since the discovery of cosmic rays over a century ago, evidence of their origins has remained elusive. Deflected by galactic magnetic fields, the only direct evidence of their origin and propagation remain encoded in their energy distribution and chemical composition. Current models of galactic cosmic rays predict variations of the energy distribution of individual elements in an energy region around 3x1015 eV known as the knee. This work presents a method to measure the energy distribution of individual elemental groups in the knee region and its application to a year of data from the IceCube detector. The method uses cosmic rays detected by both IceTop, the surface-array component, and the deep-ice component of IceCube during the 2009-2010 operation of the IC-59 detector. IceTop is used to measure the energy and the relative likelihood of the mass composition using the signal from the cosmic-ray induced extensive air shower reaching the surface. IceCube, 1.5 km below the surface, measures the energy of the high-energy bundle of muons created in the very first interactions after the cosmic ray enters the atmosphere. These event distributions are fit by a constrained model derived from detailed simulations of cosmic rays representing five chemical elements. The results of this analysis are evaluated in terms of the theoretical uncertainties in cosmic-ray interactions and seasonal variations in the atmosphere. The improvements in high-energy cosmic ray hadronic-interaction models informed by this analysis, combined with increased data from subsequent operation of the IceCube detector, could provide crucial limits on the origin of cosmic rays and their propagation through the galaxy. In the course of developing this method, a number of analysis and statistical techniques were developed to deal with the difficulties inherent in this type of measurement. These include a composition-sensitive air shower reconstruction technique, a method to model simulated event

Variations in Depth and Chemical Composition of Groundwater During an Interval in Intermittent Water Delivery.

PubMed

Yongjin, Chen; Weihong, Li; Jiazhen, Liu; Ming, Lu; Mengchen, Xu; Shengliang, Liu

2015-08-01

Based on monitoring data collected from 2006 to 2009 at the lower reaches of the Tarim River, tempo-spatial variations in groundwater depth and chemistry during an approximately 3-year interval of intermittent water delivery were studied. Results indicate that as the groundwater depth increased at the upper sector of the river's lower reaches from March 2007 to September 2009, so too did the main chemical composition of groundwater. Groundwater depth at the intermediate sector also increased, but major ions in groundwater declined. The groundwater depth at the lower sector started to decrease in August 2008, and the concentrations of main ions in the groundwater generally rose and fell along with the variations in groundwater depth. The groundwater depth and chemistry in the monitoring wells located at a distance from the aqueduct expressed complex changes at different sections. For instance, at the section near the Daxihaizi Reservoir Section B, groundwater depth increased gradually, but chemical composition changed little. In contrast, the groundwater depth of monitoring wells far from the Daxihaizi Reservoir (Section I) decreased and salt content in the groundwater increased. In sectors at a moderate distance from the reservoir, groundwater depth decreased and concentrations of main ions significantly increased.

Constraints on Meteoric Smoke Composition and Meteoric Influx Using SOFIE Observations With Models

NASA Astrophysics Data System (ADS)

Hervig, Mark E.; Brooke, James S. A.; Feng, Wuhu; Bardeen, Charles G.; Plane, John M. C.

2017-12-01

The composition of meteoric smoke particles in the mesosphere is constrained using measurements from the Solar Occultation For Ice Experiment (SOFIE) in conjunction with models. Comparing the multiwavelength observations with models suggests smoke compositions of magnetite, wüstite, magnesiowüstite, or iron-rich olivine. Smoke compositions of pure pyroxene, hematite, iron-poor olivine, magnesium silicate, and silica are excluded, although this may be because these materials have weak signatures at the SOFIE wavelengths. Information concerning smoke composition allows the SOFIE extinction measurements to be converted to smoke volume density. Comparing the observed volume density with model results for varying meteoric influx (MI) provides constraints on the ablated fraction of incoming meteoric material. The results indicate a global ablated MI of 3.3 ± 1.9 t d-1, which represents only iron, magnesium, and possibly silica, given the smoke compositions indicated here. Considering the optics and iron content of individual smoke compositions gives an ablated Fe influx of 1.8 ± 0.9 t d-1. Finally, the global total meteoric influx (ablated plus surviving) is estimated to be 30 ± 18 t d-1, when considering the present results and a recent description of the speciation of meteoric material.

Thermal and Compositional Variation of Glassy Metal Structure Factors.

NASA Astrophysics Data System (ADS)

From, Milton

The x-ray total structure factor of the glassy -metal alloys Mg_{70}Zn_ {30}, Ca_{70}Mg_{30 } and Mg_{85.5}Cu _{14.5} has been measured at three temperatures: 9K, 150K, and 300K. The data have a statistical precision of about.8% and an absolute accuracy of roughly 3%. Percus-Yevick hard sphere structure factors may be fitted quite accurately to the data in the region of the first peak. In addition, the variation of the experimental structure factor with composition is found to be consistent with the Percus-Yevick theory. At low k values, Percus -Yevick and other theoretical model structure factors are in poor agreement with the data. Within experimental error, the temperature dependence of the structure factors is in agreement with the Debye plane wave phonon model of atomic vibrations. The measured structure factors are used to calculate the electrical resistivity from the Faber-Ziman equation. In most cases, the calculations yield both the correct magnitude of resistivity and sign of the temperature coefficient of resistivity.

Nineteenth century Parisian smoke variations inferred from Eiffel Tower atmospheric electrical observations

NASA Astrophysics Data System (ADS)

Harrison, R. G.; Aplin, K. L.

Atmospheric electrical measurements provide proxy data from which historic smoke pollution levels can be determined. This approach is applied to infer autumnal Parisian smoke levels in the 1890s, based on atmospheric electric potential measurements made at the surface and the summit of the Eiffel Tower (48.7°N, 2.4°E). A theoretical model of the development of the autumn convective boundary layer is used to determine when local pollution effects dominated the Eiffel Tower potential measurements. The diurnal variation of the Eiffel Tower potential showed a single oscillation, but it differs from the standard oceanic air potential gradient (PG) variations during the period 09-17 UT, when the model indicates that the Eiffel Tower summit should be within the boundary layer. Outside these hours, the potential changes closely follow the clean air PG variation: this finding is used to calibrate the Eiffel Tower measurements. The surface smoke pollution concentration found during the morning maximum was 60±30 μg m -3, substantially lower than the values previously inferred for Kew in 1863. A vertical smoke profile was also derived using a combination of the atmospheric electrical data and boundary layer meteorology theory. Midday smoke concentration decreased with height from 60 μg m -3 at the surface to 15 μg m -3 at the top of the Eiffel Tower. The 19th century PG measurements in both polluted and clean Parisian air present a unique resource for European air pollution and atmospheric composition studies, and early evidence of the global atmospheric electrical circuit.

Interannual variation of the surface temperature of tropical forests from satellite observations

DOE PAGES

Gao, Huilin; Zhang, Shuai; Fu, Rong; ...

2016-01-01

Land surface temperatures (LSTs) within tropical forests contribute to climate variations. However, observational data are very limited in such regions. This study used passive microwave remote sensing data from the Special Sensor Microwave/Imager (SSM/I) and the Special Sensor Microwave Imager Sounder (SSMIS), providing observations under all weather conditions, to investigate the LST over the Amazon and Congo rainforests. The SSM/I and SSMIS data were collected from 1996 to 2012. The morning and afternoon observations from passive microwave remote sensing facilitate the investigation of the interannual changes of LST anomalies on a diurnal basis. As a result of the variability ofmore » cloud cover and the corresponding reduction of solar radiation, the afternoon LST anomalies tend to vary more than the morning LST anomalies. The dominant spatial and temporal patterns for interseasonal variations of the LST anomalies over the tropical rainforest were analyzed. The impacts of droughts and El Niños on this LST were also investigated. Lastly, the differences between early morning and late afternoon LST anomalies were identified by the remote sensing product, with the morning LST anomalies controlled by humidity (according to comparisons with the National Centers for Environmental Prediction (NCEP) reanalysis data).« less

Reduction of observer variation using matched CT-PET for lung cancer delineation: A three-dimensional analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Steenbakkers, Roel; Duppen, Joop C.; Fitton, Isabelle

2006-02-01

Purpose: Target delineation using only CT information introduces large geometric uncertainties in radiotherapy for lung cancer. Therefore, a reduction of the delineation variability is needed. The impact of including a matched CT scan with 2-[{sup 18}F]fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) and adaptation of the delineation protocol and software on target delineation in lung cancer was evaluated in an extensive multi-institutional setting and compared with the delineations using CT only. Methods and Materials: The study was separated into two phases. For the first phase, 11 radiation oncologists (observers) delineated the gross tumor volume (GTV), including the pathologic lymph nodes of 22more » lung cancer patients (Stages I-IIIB) on CT only. For the second phase (1 year later), the same radiation oncologists delineated the GTV of the same 22 patients on a matched CT-FDG-PET scan using an adapted delineation protocol and software (according to the results of the first phase). All delineated volumes were analyzed in detail. The observer variation was computed in three dimensions by measuring the distance between the median GTV surface and each individual GTV. The variation in distance of all radiation oncologists was expressed as a standard deviation. The observer variation was evaluated for anatomic regions (lung, mediastinum, chest wall, atelectasis, and lymph nodes) and interpretation regions (agreement and disagreement; i.e., >80% vs. <80% of the radiation oncologists delineated the same structure, respectively). All radiation oncologist-computer interactions were recorded and analyzed with a tool called 'Big Brother.' Results: The overall three-dimensional observer variation was reduced from 1.0 cm (SD) for the first phase (CT only) to 0.4 cm (SD) for the second phase (matched CT-FDG-PET). The largest reduction in the observer variation was seen in the atelectasis region (SD 1.9 cm reduced to 0.5 cm). The mean ratio between the

Responses of leaf traits to climatic gradients: adaptive variation versus compositional shifts

NASA Astrophysics Data System (ADS)

Meng, T.-T.; Wang, H.; Harrison, S. P.; Prentice, I. C.; Ni, J.; Wang, G.

2015-09-01

, but Parea increased with temperature. Although the adaptive nature of many of these trait-climate relationships is understood qualitatively, a key challenge for modelling is to predict them quantitatively. Models must take into account that community-level responses to climatic gradients can be influenced by shifts in PFT composition, such as the replacement of deciduous by evergreen trees, which may run either parallel or counter to trait variation within PFTs. The importance of PFT shifts varies among traits, being important for biophysical traits but less so for physiological and chemical traits. Finally, models should take account of the diversity of trait values that is found in all sites and PFTs, representing the "pool" of variation that is locally available for the natural adaptation of ecosystem function to environmental change.

VARIATIONS OF THE 10 mum SILICATE FEATURES IN THE ACTIVELY ACCRETING T TAURI STARS: DG Tau AND XZ Tau

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bary, Jeffrey S.; Leisenring, Jarron M.; Skrutskie, Michael F., E-mail: jbary@colgate.ed, E-mail: jml2u@virginia.ed, E-mail: mfs4n@virginia.ed

2009-11-20

Using the Infrared Spectrograph aboard the Spitzer Space Telescope, we observed multiple epochs of 11 actively accreting T Tauri stars in the nearby Taurus-Auriga star-forming region. In total, 88 low-resolution mid-infrared spectra were collected over 1.5 years in Cycles 2 and 3. The results of this multi-epoch survey show that the 10 mum silicate complex in the spectra of two sources-DG Tau and XZ Tau-undergoes significant variations with the silicate feature growing both weaker and stronger over month- and year-long timescales. Shorter timescale variations on day- to week-long timescales were not detected within the measured flux errors. The time resolutionmore » coverage of this data set is inadequate for determining if the variations are periodic. Pure emission compositional models of the silicate complex in each epoch of the DG Tau and XZ Tau spectra provide poor fits to the observed silicate features. These results agree with those of previous groups that attempted to fit only single-epoch observations of these sources. Simple two-temperature, two-slab models with similar compositions successfully reproduce the observed variations in the silicate features. These models hint at a self-absorption origin of the diminution of the silicate complex instead of a compositional change in the population of emitting dust grains. We discuss several scenarios for producing such variability including disk shadowing, vertical mixing, variations in disk heating, and disk wind events associated with accretion outbursts.« less

Diagnosis of seasonal variations of tropical cyclogenesis over the South China Sea using a genesis potential index

NASA Astrophysics Data System (ADS)

Wang, Lei; Pan, Xiumei

2012-09-01

This study examines the seasonal variations of tropical cyclogenesis over the South China Sea (SCS) using a genesis potential (GP) index developed by Emanuel and Nolan. How different environmental factors (including low-level vorticity, mid-level relative humidity, vertical wind shear, and potential intensity) contribute to these variations is investigated. Composite anomalies of the GP index are produced for the summer and winter monsoons separately. These composites replicate the observed seasonal variations of the observed frequency and location of tropical cyclogenesis over the SCS. The degree of contribution by each factor in different regions is determined quantitatively by producing composites of modified indices in which only one of the contributing factors varies, with the others set to climatology. Over the northern SCS, potential intensity makes the largest contributions to the seasonal variations in tropical cyclogenesis. Over the southern SCS, the low-level relative vorticity plays the primary role in the seasonal modulation of tropical cyclone (TC) genesis frequency, and the vertical wind shear plays the secondary role. Thermodynamic factors play more important roles for the seasonal variations in tropical cyclogenesis over the northern SCS, while dynamic factors are more important in the seasonal modulation of TC genesis frequency over the southern SCS.

Seasonal and geographical variations in the biochemical composition of the blue mussel (Mytilus edulis L.) from Ireland.

PubMed

Fernández, Ayoa; Grienke, Ulrike; Soler-Vila, Anna; Guihéneuf, Freddy; Stengel, Dagmar B; Tasdemir, Deniz

2015-06-15

Blue mussel (Mytilus edulis L.) farming constitutes the largest volume of the shellfish sector in Ireland. Recently, interest in mussel dietary supplements and functional foods has increased significantly. To identify the optimal harvesting time and location in Ireland, blue mussels were investigated for their biochemical composition over a period of one year. The study included samples from aquaculture facilities, wild grown mussels and waste material. Each sample was analysed at four time points to determine the total content of (i) glycogen, (ii) lipids, (iii) proteins, (iv) inorganic substances, and (v) energy. Moreover, fatty acid profiles were investigated by GC-FID revealing high contents of PUFAs and a high ω-3/ω-6 ratio. Compared to less pronounced geographical variations, distinct seasonal trends could be observed for all samples. The content of the investigated metabolite classes, inorganic substances, and energy was at a maximum level in spring or late summer. Copyright © 2014 Elsevier Ltd. All rights reserved.

The effect of the interplanetary magnetic field on sidereal variations observed at medium depth underground detectors

NASA Technical Reports Server (NTRS)

Humble, J. E.; Fenton, A. G.

1985-01-01

It has been known for some years that the intensity variations in sidereal time observed by muon detectors at moderate underground depths are sensitive to the polarity of the interplanetary magnetic field (ipmf) near the Earth. There are differences in the response to these anisotropies as observed in the Norhtern and southern hemispheres. When fully understood, the nature of the anisotropy seems likely to provide information on the 3-dimensional structure of the heliomagnetosphere, its time variations, and its linking with the local interstellar field. The summation harmonic dials for the sidereal diurnal variation during 1958 to 1982 show that there is a strong dependence on whether the ipmf near the Earth is directed outwards from the Sun or inwards it.

High Frequency Variations of Earth Rotation Parameters from GPS and GLONASS Observations

PubMed Central

Wei, Erhu; Jin, Shuanggen; Wan, Lihua; Liu, Wenjie; Yang, Yali; Hu, Zhenghong

2015-01-01

The Earth's rotation undergoes changes with the influence of geophysical factors, such as Earth's surface fluid mass redistribution of the atmosphere, ocean and hydrology. However, variations of Earth Rotation Parameters (ERP) are still not well understood, particularly the short-period variations (e.g., diurnal and semi-diurnal variations) and their causes. In this paper, the hourly time series of Earth Rotation Parameters are estimated using Global Positioning System (GPS), Global Navigation Satellite System (GLONASS), and combining GPS and GLONASS data collected from nearly 80 sites from 1 November 2012 to 10 April 2014. These new observations with combining different satellite systems can help to decorrelate orbit biases and ERP, which improve estimation of ERP. The high frequency variations of ERP are analyzed using a de-trending method. The maximum of total diurnal and semidiurnal variations are within one milli-arcseconds (mas) in Polar Motion (PM) and 0.5 milli-seconds (ms) in UT1-UTC. The semidiurnal and diurnal variations are mainly related to the ocean tides. Furthermore, the impacts of satellite orbit and time interval used to determinate ERP on the amplitudes of tidal terms are analyzed. We obtain some small terms that are not described in the ocean tide model of the IERS Conventions 2010, which may be caused by the strategies and models we used or the signal noises as well as artifacts. In addition, there are also small differences on the amplitudes between our results and IERS convention. This might be a result of other geophysical excitations, such as the high-frequency variations in atmospheric angular momentum (AAM) and hydrological angular momentum (HAM), which needs more detailed analysis with more geophysical data in the future. PMID:25635416

CLASP/SJ Observations of Rapid Time Variations in the Ly α Emission in a Solar Active Region

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ishikawa, Shin-nosuke; Kubo, Masahito; Katsukawa, Yukio

The Chromospheric Ly α SpectroPolarimeter (CLASP) is a sounding rocket experiment launched on 2015 September 3 to investigate the solar chromosphere and transition region. The slit-jaw (SJ) optical system captured Ly α images with a high time cadence of 0.6 s. From the CLASP/SJ observations, many variations in the solar chromosphere and transition region emission with a timescale of <1 minute were discovered. In this paper, we focus on the active region within the SJ field of view and investigate the relationship between short (<30 s) temporal variations in the Ly α emission and the coronal structures observed by Solarmore » Dynamics Observatory/Atmospheric Imaging Assembly (AIA). We compare the Ly α temporal variations at the coronal loop footpoints observed in the AIA 211 Å (≈2 MK) and AIA 171 Å (≈0.6 MK) channels with those in the regions with bright Ly α features without a clear association with the coronal loop footpoints. We find more short (<30 s) temporal variations in the Ly α intensity in the footpoint regions. Those variations did not depend on the temperature of the coronal loops. Therefore, the temporal variations in the Ly α intensity at this timescale range could be related to the heating of the coronal structures up to temperatures around the sensitivity peak of 171 Å. No signature was found to support the scenario that these Ly α intensity variations were related to the nanoflares. Waves or jets from the lower layers (lower chromosphere or photosphere) are possible causes for this phenomenon.« less

Which processes drive observed variations of HCHO columns over India?

NASA Astrophysics Data System (ADS)

Surl, Luke; Palmer, Paul I.; González Abad, Gonzalo

2018-04-01

We interpret HCHO column variations observed by the Ozone Monitoring Instrument (OMI), aboard the NASA Aura satellite, over India during 2014 using the GEOS-Chem atmospheric chemistry and transport model. We use a nested version of the model with a horizontal resolution of approximately 25 km. HCHO columns are related to local emissions of volatile organic compounds (VOCs) with a spatial smearing that increases with the VOC lifetime. Over India, HCHO has biogenic, pyrogenic, and anthropogenic VOC sources. Using a 0-D photochemistry model, we find that isoprene has the largest molar yield of HCHO which is typically realized within a few hours. We also find that forested regions that neighbour major urban conurbations are exposed to high levels of nitrogen oxides. This results in depleted hydroxyl radical concentrations and a delay in the production of HCHO from isoprene oxidation. We find that propene is the only anthropogenic VOC emitted in major Indian cities that produces HCHO at a comparable (but slower) rate to isoprene. The GEOS-Chem model reproduces the broad-scale annual mean HCHO column distribution observed by OMI (r = 0.6), which is dominated by a distinctive meridional gradient in the northern half of the country, and by localized regions of high columns that coincide with forests. Major discrepancies are noted over the Indo-Gangetic Plain (IGP) and Delhi. We find that the model has more skill at reproducing observations during winter (JF) and pre-monsoon (MAM) months with Pearson correlations r > 0.5 but with a positive model bias of x≃1×1015 molec cm-2. During the monsoon season (JJAS) we reproduce only a diffuse version of the observed meridional gradient (r = 0.4). We find that on a continental scale most of the HCHO column seasonal cycle is explained by monthly variations in surface temperature (r = 0.9), suggesting a role for biogenic VOCs, in agreement with the 0-D and GEOS-Chem model calculations. We also find that the seasonal cycle during

Cosmic ray sidereal diurnal variation of galactic origin observed by neutron monitors

NASA Technical Reports Server (NTRS)

Ishida, Y.; Nagashima, K.; Mori, S.; Morishita, I.

1985-01-01

Cosmic ray sidereal diurnal variations observed by neutron monitors are analyzed for the period 1961 to 1978, by adding 134 station years data to the previous paper (Nagashima, et al., 1983). Also the dependence of the sidereal variations on Sun's polar magnetic field polarity is examined for two periods; the period of negative polarity in the northern region, 1961 to 1969 and the period of positive polarity, 1970 to 1978. It is obtained that for the former period, the amplitude A=0.0203 + or 0.0020% and the phase phi=6.1 + or - 0.4 h LST and for the latter period, 0.0020% and phi=8.6 + or - 4 h LST, respectively.

Seasonal Variation in Dissolved Organic Matter Composition and Photoreactivity within a Small Sub-arctic Stream.

NASA Astrophysics Data System (ADS)

Guerard, J.; Osborne, R.

2015-12-01

Dissolved organic matter (DOM) is a complex heterogeneous mixture, ubiquitous to all natural surface waters, uniquely composed of source inputs specific to spatial, temporal, and ecological circumstances. In arctic and sub-arctic regions, elucidating DOM composition and reactivity is complicated by seasonal variations. These include changes in productivity and source inputs to the water column, as well as winter overflow events that may contribute allochthonous organic material. DOM from a small boreal stream in a watershed of discontinuous permafrost in the Goldstream Valley of interior Alaska was isolated by solid-phase extraction (PPL) at multiple points during the year - late spring, late summer, and in the winter during an active overflow event. Compositional characteristics of each of the isolates were characterized by SPR-W5-WATERGATE 1H NMR spectroscopy, specific UV-Vis absorbance, and excitation emission matrix (EEM) fluorescence spectroscopy and compared against end-member reference DOM isolates. Kinetics of photobleaching experiments reveal the influence of compositional differences among the isolated DOMs on their chemical reactivity, and offer insight into potential differences in their source materials and ecological function throughout the year. Photobleaching studies were conducted using a variety of reactive species quenchers or sensitizers in order to assess susceptibility of oxidative transformation mechanisms on the different DOM isolates, which were then analyzed by 1H NMR, UV-Vis degradation kinetics, and parallel factor analysis (PARAFAC) of fluorescence EEMs. Better understanding of the seasonal variations of boreal DOM character and function on a molecular level is critical to assessing alterations in its ecological role and cycling in the face of current and future ecosystem perturbations in arctic and sub-arctic regions.

Aibika (Abelmoschus manihot L.): Genetic variation, morphology and relationships to micronutrient composition.

PubMed

Rubiang-Yalambing, Lydia; Arcot, Jayashree; Greenfield, Heather; Holford, Paul

2016-02-15

Aibika (Abelmoschus manihot L.) is believed to be a good source of micronutrients. However, although many varieties of aibika are commonly consumed in Papua New Guinea, their micronutrient content is unknown. Therefore, the mineral (Ca, Fe, K, Mg, Mn, Na, Zn & Cu), folate composition and the genetic variation of 23 aibika accessions from the collection at the National Agricultural Research Institute were studied over a 3year period to provide data for nutritional studies and to inform breeding programs. The data showed that aibika is, potentially, a crop of high nutritional value with the potential to boost the micronutrient status of local PNG communities. However, there were substantial differences in the micronutrient concentrations of the accessions from year to year and accessions that had the highest concentration of a particular mineral in 1year did not have the high concentrations in other years. Clusters determined using unweighted pair group method with arithmetic mean analysis (UPGMA) of the micronutrient contents differed in each of the 3years. Genetic analysis made using random amplification of polymorphic DNA and directed amplification of mini satellite region DNA placed the accessions into five groups. There was no correlation between these groups and leaf morphology, nor were there correlations with the clusters determined from the UPGMA analyses. There appears to be considerable interaction between genotype and environmental factors determining micronutrient composition and environmental factors may play a greater role than genotype in influencing micronutrient composition. Copyright © 2014 Elsevier Ltd. All rights reserved.

Secular gravity variation at Svalbard (Norway) from ground observations and GRACE satellite data

NASA Astrophysics Data System (ADS)

Mémin, A.; Rogister, Y.; Hinderer, J.; Omang, O. C.; Luck, B.

2011-03-01

The Svalbard archipelago, Norway, is affected by both the present-day ice melting (PDIM) and Glacial Isostatic Adjustment (GIA) subsequent to the Last Pleistocene deglaciation. The induced deformation of the Earth is observed by using different techniques. At the Geodetic Observatory in Ny-Ålesund, precise positioning measurements have been collected since 1991, a superconducting gravimeter (SG) has been installed in 1999, and six campaigns of absolute gravity (AG) measurements were performed between 1998 and 2007. Moreover, the Gravity Recovery and Climate Experiment (GRACE) satellite mission provides the time variation of the Earth gravity field since 2002. The goal of this paper is to estimate the present rate of ice melting by combining geodetic observations of the gravity variation and uplift rate with geophysical modelling of both the GIA and Earth's response to the PDIM. We estimate the secular gravity variation by superimposing the SG series with the six AG measurements. We collect published estimates of the vertical velocity based on GPS and VLBI data. We analyse the GRACE solutions provided by three groups (CSR, GFZ, GRGS). The crux of the problem lies in the separation of the contributions from the GIA and PDIM to the Earth's deformation. To account for the GIA, we compute the response of viscoelastic Earth models having different radial structures of mantle viscosity to the deglaciation histories included in the models ICE-3G or ICE-5G. To account for the effect of PDIM, we compute the deformation of an elastic Earth model for six models of ice-melting extension and rates. Errors in the gravity variation and vertical velocity are estimated by taking into account the measurement uncertainties and the variability of the GRACE solutions and GIA and PDIM models. The ground observations agree with models that involve a current ice loss of 25 km3 water equivalent yr-1 over Svalbard, whereas the space observations give a value in the interval [5, 18] km3

Representative composition of the Murray Formation, Gale Crater, Mars, as refined through modeling utilizing Alpha Particle X-ray Spectrometer observations

NASA Astrophysics Data System (ADS)

VanBommel, Scott; Gellert, Ralf; Berger, Jeff; Desouza, Elstan; O'Connell-Cooper, Catherine; Thompson, Lucy; Boyd, Nicholas

2017-04-01

The Murray formation[1] in Gale Crater is distinctly characterized by depleted MgO and CaO, an elevated Fe/Mn ratio, and enrichments in SiO2, K2O, and Ge, compared to average Mars. Supported by observations with Curiosity's Alpha Particle X-ray Spectrometer[2], this pattern is consistent over several kilometers. However, intermixed dust, Ca-, and Mg-sulfates introduce chemical heterogeneities into the APXS field of view. Better constraints on the composition of what is characteristic of the Murray formation is achieved by applying a least-squares deconvolution[3] to a selection of APXS Murray targets. We subtract the composition of known additions (dust[4], MgSO4, CaSO4) to derive a more-representative Murray composition. Slight variations within Murray are then probed by modeling each target as a mixture of dust, sulfates and the derived representative Murray. The derived composition for what is representative of Murray has several key deviations from the straightforward average of Murray targets. The subtraction of known dust, Mg-, and Ca-sulfate additions suggests further depletion in MgO and CaO in Murray and also suggests a significant decrease in SO3 concentration compared to the average of Murray targets. While veins and concretions are contaminants when considering the composition of the bulk rock, the subtraction of Mg- or Ca-sulfate is independent of sulfate form. Sulfates within the bulk rock (detrital or cements) have been observed in the Murray formation. These sulfates are important and discussed further in [5]. Modeling APXS Murray targets as a mixture of dust, MgSO4, CaSO4, and representative Murray, provides insight into potential subtle variations within the surprisingly consistent Murray formation. For example, the high SiO2 in Buckskin, (sol 1057-1091) is not simply a mixture of representative Murray with sulfates and dust. The elevated Ni (and MgSO4) of Morrison (sol ˜775), the elevated Al2O3 of Mojave (sol ˜800-900), and the gradually

Diversity of Rock Compositions at Gale Crater Observed by ChemCam and APXS on Curiosity, and Comparison to Meteorite and Orbital Observations

NASA Astrophysics Data System (ADS)

Wiens, R. C.; Maurice, S.; Grotzinger, J. P.; Gellert, R.; Mangold, N.; Sautter, V.; Ollila, A.; Dyar, M. D.; Le Mouelic, S.; Ehlmann, B. L.; Clegg, S. M.; Lanza, N.; Cousin, A.; Forni, O.; Gasnault, O.; Lasue, J.; Blaney, D. L.; Newsom, H. E.; Herkenhoff, K. E.; Anderson, R. B.; D'Uston, L.; Bridges, N. T.; Fabre, C.; Meslin, P.; Johnson, J.; Vaniman, D.; Bridges, J.; Dromart, G.; Schmidt, M. E.; Team, M.

2013-12-01

Gale crater was selected as the Curiosity landing site because of the apparent sedimentary spectral signatures seen from orbit. Sedimentary materials on Mars have to this point showed very little expression of major element mobility, so compositions of precursor igneous minerals play a strong role in the compositions of sediments. In addition, pebbles and float rocks on Bradbury Rise (sols 0-50, > 324) appear to be mostly igneous in origin, and are assumed to have been carried down from the crater rim. Overall in the first year on Mars ChemCam obtained >75,000 LIBS spectra on > 2,000 observation points, supported by > 1,000 RMI images, and APXS obtained a significant number of observations. These show surprisingly variable compositions. The mean ChemCam compositions for Bradbury Rise dust-free rocks and pebbles (62 locations) give SiO2 = 56%, FeOT = 16% and show high alkalis consistent with Jake Matijevic (sol ~47) APXS Na2O ~6.6 wt%. ChemCam observations on the conglomerate Link (sol 27) gave Rb > 150 ppm and Sr > 1500 ppm. These compositions imply the presence of abundant alkali feldspars in the material infilling the lower parts of Gale crater. They are generally consistent with the more feldspar-rich SNC meteorites but show a radical departure from larger scale orbital observations, e.g., GRS, raising the question of how widespread these compositions are outside of Gale crater. Sedimentary materials at Yellowknife Bay encompassing the Sheepbed (sols 125-300) and Shaler (sols 121, 311-324) units, potentially including Point Lake (sols 301-310) and Rocknest (sols 57-97), appear to have incorporated varying amounts of igneous source materials. Seven rocks investigated at Rocknest show significant additions of Fe, with mean FeOT = 25% (154 locations), suggesting that FeO was a cementing agent. ChemCam observations at Shaler show varying amounts of alkali feldspar (i.e., related to Bradbury Rise), Fe-rich material (Rocknest-like), and potassium-rich material

Examining the validity of AHRQ's patient safety indicators (PSIs): is variation in PSI composite score related to hospital organizational factors?

PubMed

Shin, Marlena H; Sullivan, Jennifer L; Rosen, Amy K; Solomon, Jeffrey L; Dunn, Edward J; Shimada, Stephanie L; Hayes, Jennifer; Rivard, Peter E

2014-12-01

Increasing use of Agency for Healthcare Research and Quality's Patient Safety Indicators (PSIs) for hospital performance measurement intensifies the need to critically assess their validity. Our study examined the extent to which variation in PSI composite score is related to differences in hospital organizational structures or processes (i.e., criterion validity). In site visits to three Veterans Health Administration hospitals with high and three with low PSI composite scores ("low performers" and "high performers," respectively), we interviewed a cross-section of hospital staff. We then coded interview transcripts for evidence in 13 safety-related domains and assessed variation across high and low performers. Evidence of leadership and coordination of work/communication (organizational process domains) was predominantly favorable for high performers only. Evidence in the other domains was either mixed, or there were insufficient data to rate the domains. While we found some evidence of criterion validity, the extent to which variation in PSI rates is related to differences in hospitals' organizational structures/processes needs further study. © The Author(s) 2014.

How Surface Composition and Meteoroid Impacts Mediate Sodium and Potassium in the Lunar Exosphere

NASA Technical Reports Server (NTRS)

Colaprete, A.; Sarantos, M.; Wooden, D. H.; Stubbs, T. J.; Cook, A. M.; Shirley, M.

2016-01-01

Despite being trace constituents of the lunar exosphere, sodium and potassium are the most readily observed species due to their bright line emission. Measurements of these species by the Ultraviolet and Visible Spectrometer (UVS) on the Lunar Atmosphere and Dust Environment Explorer (LADEE) have revealed unambiguous temporal and spatial variations indicative of a strong role for meteoroid bombardment and surface composition in determining the composition and local time dependence of the Moon's exosphere. Observations show distinct lunar day (monthly) cycles for both species as well as an annual cycle for sodium. The first continuous measurements for potassium show a more repeatable variation across lunations and an enhancement over KREEP (Potassium Rare Earth Elements and Phosphorus) surface regions, revealing a strong dependence on surface composition.

The Preparation and Characterization of INTEC HAW Phase I Composition Variation Study Glasses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Musick, C. A.; Peeler, D. K.; Piepel, G. F.

1999-03-01

A glass composition variation study (CVS) is in progress to define formulations for the vitrification of high activity waste (HAW) proposed to be separated from dissolved calcine stored at the Idaho National Engineering and Environmental Laboratory (INEEL). Estimates of calcine and HAW compositions prepared in FY97 were used to define test matrix glasses. The HAW composition is of particular interest because high aluminum, zirconium, phosphorous and potassium, and low iron and sodium content places it outside the realm of vitrification experience in the Department of Energy (DOE) complex. Through application of statistical techniques, a test matrix was defined for Phasemore » 1 of the CVS. From this matrix, formulations were systematically selected for preparation and characterization with respect to homogeneity, viscosity, liquidus temperature (TL), and leaching response when subjected to the Product Consistency Test (PCT). Based on the properties determined, certain formulations appear suitable for further development including use in planning Phase 2 of the study. It is recommended that glasses to be investigated in Phase 2 be limited to 3-5 wt % phosphate. The results of characterizing the Phase 1 glasses are presented in this document. A full analysis of the composition-property relationships of glasses being developed for immobilizing HAWs will be performing at the completion of CVS phases. This analysis will be needed for the optimization of the glass formulations of vitrifying HAW. Contributions were made to this document by personnel working at the INEEL, Pacific Northwest National Laboratories (PNNL), and the Savannah River Technology Center (SRTC).« less

The role of ensemble-based statistics in variational assimilation of cloud-affected observations from infrared imagers

NASA Astrophysics Data System (ADS)

Hacker, Joshua; Vandenberghe, Francois; Jung, Byoung-Jo; Snyder, Chris

2017-04-01

Effective assimilation of cloud-affected radiance observations from space-borne imagers, with the aim of improving cloud analysis and forecasting, has proven to be difficult. Large observation biases, nonlinear observation operators, and non-Gaussian innovation statistics present many challenges. Ensemble-variational data assimilation (EnVar) systems offer the benefits of flow-dependent background error statistics from an ensemble, and the ability of variational minimization to handle nonlinearity. The specific benefits of ensemble statistics, relative to static background errors more commonly used in variational systems, have not been quantified for the problem of assimilating cloudy radiances. A simple experiment framework is constructed with a regional NWP model and operational variational data assimilation system, to provide the basis understanding the importance of ensemble statistics in cloudy radiance assimilation. Restricting the observations to those corresponding to clouds in the background forecast leads to innovations that are more Gaussian. The number of large innovations is reduced compared to the more general case of all observations, but not eliminated. The Huber norm is investigated to handle the fat tails of the distributions, and allow more observations to be assimilated without the need for strict background checks that eliminate them. Comparing assimilation using only ensemble background error statistics with assimilation using only static background error statistics elucidates the importance of the ensemble statistics. Although the cost functions in both experiments converge to similar values after sufficient outer-loop iterations, the resulting cloud water, ice, and snow content are greater in the ensemble-based analysis. The subsequent forecasts from the ensemble-based analysis also retain more condensed water species, indicating that the local environment is more supportive of clouds. In this presentation we provide details that explain the

Seasonal variations in the nitrogen isotope composition of Okinotori coral in the tropical western Pacific: A new proxy for marine nitrate dynamics

NASA Astrophysics Data System (ADS)

Yamazaki, Atsuko; Watanabe, Tsuyoshi; Ogawa, Nanako O.; Ohkouchi, Naohiko; Shirai, Kotaro; Toratani, Mitsuhiro; Uematsu, Mitsuo

2011-12-01

To demonstrate the utility of coral skeletons as a recorder of nitrate dynamics in the surface ocean, we collected coral skeletons of Porites lobata and determined their nitrogen isotope composition (δ15Ncoral) from 2002 to 2006. Skeletons were collected at Okinotori Island in southwestern Japan, far from any sources of terrestrial nitrogen. Nitrogen isotope compositions along the growth direction were determined at 800 μm intervals (˜1 month resolution) and compared against the skeletal carbon isotope composition (δ13Ccoral-carb), barium/calcium ratio (Ba/Ca), and Chlorophyll-a concentration (Chl-a). From 2002 to 2004, ratios of the δ15Ncoral varied between +0.8 and +8.3‰ with inverse variation to SST (r = -0.53). Ba/Ca ratios and Chl-a concentrations were also observed to be high during seasons with low SST. These results suggested that the vertical mixing that occurs during periods of low SST carries nutrients from deeper water (δ15NDIN; +5˜+6‰) to the sea surface. In 2005 onward, δ15Ncoral and Ba/Ca ratios also had positive peaks even in high SST during periods of transient upwelling caused by frequent large typhoons (maximum wind speed 30 m/s). In addition, low δ15Ncoral (+0.8˜+2.0‰) four months after the last typhoon implied nitrogen fixation because of the lack of typhoon upwelling through the four years record of δ15Ncoral. Variations in the δ13Ccoral-carb and δ15Ncoral were synchronized, suggesting that nitrate concentration could control zooxanthellae photosynthesis. Our results suggested that δ15Ncoral holds promise as a proxy for reconstructing the transport dynamics of marine nitrate and thus also a tool for estimating nitrate origins in the tropical and subtropical oceans.

Whole body-element composition of Atlantic salmon Salmo salar influenced by migration direction and life stage in three distinct populations.

PubMed

Ebel, J D; Leroux, S J; Robertson, M J; Dempson, J B

2016-11-01

Body-element content was measured for three life stages of wild Atlantic salmon Salmo salar from three distinct Newfoundland populations as individuals crossed between freshwater and marine ecosystems. Life stage explained most of the variation in observed body-element concentration whereas river of capture explained very little variation. Element composition of downstream migrating post-spawn adults (i.e. kelts) and juvenile smolts were similar and the composition of these two life stages strongly differed from adults migrating upstream to spawn. Low variation within life stages and across populations suggests that S. salar may exert rheostatic control of their body-element composition. Additionally, observed differences in trace element concentration between adults and other life stages were probably driven by the high carbon concentration in adults because abundant elements, such as carbon, can strongly influence the observed concentrations of less abundant elements. Thus, understanding variation among individuals in trace elements composition requires the measurement of more abundant elements. Changes in element concentration with ontogeny have important consequences the role of fishes in ecosystem nutrient cycling and should receive further attention. © 2016 The Fisheries Society of the British Isles.

Temporal variation in chemical composition of phenocrysts and magmatic temperature at Daisen volcano, southwest Japan

NASA Astrophysics Data System (ADS)

Tsukui, Masashi

1985-12-01

Daisen volcano, located in the San'in district, southwest Japan, started its activity in the middle Pleistocene and continued until at least ca. 20,000 yr B.P. The volcano is composed entirely of dacitic pyroclastic materials, lava domes and subordinate thick lava flows. Its activity is divided into two groups, Older (1.0-0.4 Ma) and Younger (0.4 Ma to ca. 17.000 yr B.P.). Chemical compositions of phenocrysts in the members of the Upper Tephra Group (the last 150,000 years) in the Younger Group were examined in detail by electron microprobe analysis. The compositions of phenocryst minerals change systematically and cyclically with the order of eruptions. Phenocrysts with less differentiated compositions were found in the products of eruptions 60,000 and 20,000 years ago. The variation patterns of inferred magma temperature (estimated by the Fe-Ti oxide geothermometer) with time are well correlated with those of the chemical compositions of phenocrysts. Orthopyroxene phenocrysts generally show both reversed and normal zoning in single rock specimens and the compositional range of rims is much smaller than that of the core, indicating that the process of re-equilibration of two compositionally distinct orthopyroxenes took place. These facts could be explained by injection of less differentiated, higher-temperature magmas from a deeper level into the shallower more differentiated magma reservoir. A relatively active (frequent and/or voluminous) injection episode seems to have taken place twice during the last 150,000 years; 60,000 and 20,000 years ago.

Spatial and Temporal Variations in Titan's Surface Temperatures from Cassini CIRS Observations

NASA Technical Reports Server (NTRS)

Cottini, V.; Nixon, C. A.; Jennings, D. E.; deKok, R.; Teanby, N. A.; Irwin, P. G. J.; Flasar, F. M.

2012-01-01

We report a wide-ranging study of Titan's surface temperatures by analysis of the Moon's outgoing radiance through a spectral window in the thermal infrared at 19 mm (530/cm) characterized by lower atmospheric opacity. We begin by modeling Cassini Composite Infrared Spectrometer (CIRS) far infrared spectra collected in the period 2004-2010, using a radiative transfer forward model combined with a non-linear optimal estimation inversion method. At low-latitudes, we agree with the HASI near-surface temperature of about 94 K at 101S (Fulchignoni et al., 2005). We find a systematic decrease from the equator toward the poles, hemispherically asymmetric, of approx. 1 K at 60 deg. south and approx. 3 K at 60 deg. north, in general agreement with a previous analysis of CIRS data and with Voyager results from the previous northern winter. Subdividing the available database, corresponding to about one Titan season, into 3 consecutive periods, small seasonal changes of up to 2 K at 60 deg N became noticeable in the results. In addition, clear evidence of diurnal variations of the surface temperatures near the equator are observed for the first time: we find a trend of slowly increasing temperature from the morning to the early afternoon and a faster decrease during the night. The diurnal change is approx. 1.5 K, in agreement with model predictions for a surface with a thermal inertia between 300 and 600 J/ sq. m s (exp -1/2) / K. These results provide important constraints on coupled surface-atmosphere models of Titan's meteorology and atmospheric dynamic.

Seasonal variation of the underground cosmic muon flux observed at Daya Bay

NASA Astrophysics Data System (ADS)

An, F. P.; Balantekin, A. B.; Band, H. R.; Bishai, M.; Blyth, S.; Cao, D.; Cao, G. F.; Cao, J.; Chan, Y. L.; Chang, J. F.; Chang, Y.; Chen, H. S.; Chen, Q. Y.; Chen, S. M.; Chen, Y. X.; Chen, Y.; Cheng, J.; Cheng, Z. K.; Cherwinka, J. J.; Chu, M. C.; Chukanov, A.; Cummings, J. P.; Ding, Y. Y.; Diwan, M. V.; Dolgareva, M.; Dove, J.; Dwyer, D. A.; Edwards, W. R.; Gill, R.; Gonchar, M.; Gong, G. H.; Gong, H.; Grassi, M.; Gu, W. Q.; Guo, L.; Guo, X. H.; Guo, Y. H.; Guo, Z.; Hackenburg, R. W.; Hans, S.; He, M.; Heeger, K. M.; Heng, Y. K.; Higuera, A.; Hsiung, Y. B.; Hu, B. Z.; Hu, T.; Huang, E. C.; Huang, H. X.; Huang, X. T.; Huber, P.; Huo, W.; Hussain, G.; Jaffe, D. E.; Jen, K. L.; Jetter, S.; Ji, X. P.; Ji, X. L.; Jiao, J. B.; Johnson, R. A.; Jones, D.; Kang, L.; Kettell, S. H.; Khan, A.; Kohn, S.; Kramer, M.; Kwan, K. K.; Kwok, M. W.; Kwok, T.; Langford, T. J.; Lau, K.; Lebanowski, L.; Lee, J.; Lee, J. H. C.; Lei, R. T.; Leitner, R.; Li, C.; Li, D. J.; Li, F.; Li, G. S.; Li, Q. J.; Li, S.; Li, S. C.; Li, W. D.; Li, X. N.; Li, X. Q.; Li, Y. F.; Li, Z. B.; Liang, H.; Lin, C. J.; Lin, G. L.; Lin, S.; Lin, S. K.; Lin, Y.-C.; Ling, J. J.; Link, J. M.; Littenberg, L.; Littlejohn, B. R.; Liu, J. L.; Liu, J. C.; Loh, C. W.; Lu, C.; Lu, H. Q.; Lu, J. S.; Luk, K. B.; Ma, X. Y.; Ma, X. B.; Ma, Y. Q.; Malyshkin, Y.; Martinez Caicedo, D. A.; McDonald, K. T.; McKeown, R. D.; Mitchell, I.; Nakajima, Y.; Napolitano, J.; Naumov, D.; Naumova, E.; Ngai, H. Y.; Ochoa-Ricoux, J. P.; Olshevskiy, A.; Pan, H.-R.; Park, J.; Patton, S.; Pec, V.; Peng, J. C.; Pinsky, L.; Pun, C. S. J.; Qi, F. Z.; Qi, M.; Qian, X.; Qiu, R. M.; Raper, N.; Ren, J.; Rosero, R.; Roskovec, B.; Ruan, X. C.; Sebastiani, C.; Steiner, H.; Sun, J. L.; Tang, W.; Taychenachev, D.; Treskov, K.; Tsang, K. V.; Tull, C. E.; Viaux, N.; Viren, B.; Vorobel, V.; Wang, C. H.; Wang, M.; Wang, N. Y.; Wang, R. G.; Wang, W.; Wang, X.; Wang, Y. F.; Wang, Z.; Wang, Z.; Wang, Z. M.; Wei, H. Y.; Wen, L. J.; Whisnant, K.; White, C. G.; Whitehead, L.; Wise, T.; Wong, H. L. H.; Wong, S. C. F.; Worcester, E.; Wu, C.-H.; Wu, Q.; Wu, W. J.; Xia, D. M.; Xia, J. K.; Xing, Z. Z.; Xu, J. L.; Xu, Y.; Xue, T.; Yang, C. G.; Yang, H.; Yang, L.; Yang, M. S.; Yang, M. T.; Yang, Y. Z.; Ye, M.; Ye, Z.; Yeh, M.; Young, B. L.; Yu, Z. Y.; Zeng, S.; Zhan, L.; Zhang, C.; Zhang, C. C.; Zhang, H. H.; Zhang, J. W.; Zhang, Q. M.; Zhang, X. T.; Zhang, Y. M.; Zhang, Y. X.; Zhang, Y. M.; Zhang, Z. J.; Zhang, Z. Y.; Zhang, Z. P.; Zhao, J.; Zhou, L.; Zhuang, H. L.; Zou, J. H.

2018-01-01

The Daya Bay Experiment consists of eight identically designed detectors located in three underground experimental halls named as EH1, EH2, EH3, with 250, 265 and 860 meters of water equivalent vertical overburden, respectively. Cosmic muon events have been recorded over a two-year period. The underground muon rate is observed to be positively correlated with the effective atmospheric temperature and to follow a seasonal modulation pattern. The correlation coefficient α, describing how a variation in the muon rate relates to a variation in the effective atmospheric temperature, is found to be αEH1 = 0.362±0.031, αEH2 = 0.433±0.038 and αEH3 = 0.641±0.057 for each experimental hall.

Variations in the Nd isotope composition of Late Miocene to Early Pliocene glacially derived sediments in Prydz Bay, East Antarctica

NASA Astrophysics Data System (ADS)

Mabson, M.; Pierce, E. L.; Dale, C. L.; Williams, T.; Hemming, S. R.; van de Flierdt, T.; Cook, C.; Goldstein, S. L.

2010-12-01

Michelle Mabson (Howard University), Elizabeth Pierce (Lamont-Doherty Earth Observatory, Columbia University), Cathleen Doherty (Lamont-Doherty Earth Observatory, Columbia University), Trevor Williams (Lamont-Doherty Earth Observatory), Sidney Hemming (Lamont-Doherty Earth Observatory), Tina van de Flierdt (Imperial College London), Carys Cook (Imperial College London), Steve Goldstein (Lamont-Doherty Earth Observatory) Since initiation of major ice sheets on Antarctica at about 34 Ma, Antarctica has been a major player in global climate change. Understanding the response of the East Antarctic Ice Sheet to major climate changes through the Cenozoic has fundamental importance to both Earth Sciences and Society. Previous study of Nd isotope composition of sediments at Ocean Drilling Program (ODP) Site 1166 within Prydz Bay found evidence for variations of the Nd isotope composition between -15 to -30 epsilon units through this pre-glacial to glacial record (van de Flierdt et al., 2008, GRL). The Nd isotope composition of sediments provides an estimate for the average continental crust formation age of the sources. The sources around Prydz Bay have a wide range of formation ages, from Archean to Phanerozoic, so the areas which were being preferentially eroded can be inferred. This study seeks to contribute evidence for the local variations in provenance of sediments by extending the record of Nd isotope variations to ODP Site 739 in Prydz Bay. ODP Site 1165 has an unconformity that spans ~30-3 Ma. This part of the record is much more complete in ODP site 739, located about 200 km from the coast of Prydz Bay, probably more protected from ice stream erosion in the Prydz Channel. Because of its location we can conclude that the sediment deposited into this area is derived from the Lambert Glacier, and thus the variations in epsilon Nd will allow testing whether changes in the extent of this ice stream could lead to variations in the provenance of sediment carried by this

Using GIA observables to constrain the thermal contribution to lateral variations in mantle viscosity

NASA Astrophysics Data System (ADS)

Wu, P.; Wang, H.; van der Wal, W.; Shum, C.; Lee, H.; Braun, A.

2009-05-01

Lateral heterogeneities in the mantle can be caused by thermal, chemical and non-isotropic pre-stress effects. Here, observations of the glacial isostatic adjustment (GIA) process are used to constrain the thermal contribution to lateral variations in upper and lower mantle viscosities. The Coupled Laplace-Finite Element method is used to predict the GIA response on a spherical, self-gravitating, compressible, viscoelastic earth with self-gravitating oceans, induced by either the ICE-5G or ICE-4G deglaciation models. GIA observations include global historic relative sea level data, GPS uplift rates in Laurentide and Fennoscandia, altimetry together with tide-gauge data in the Great Lakes area, and GRACE data in Laurentide. The lateral viscosity perturbations are inferred from the high resolution seismic tomography model of Grand (2002) by using a conversion relation that takes into account both anelastic and anharmonic effects (Karato 2008). To determine the contribution of thermal effects in the upper and lower mantle, the scaling factor b is also inserted into the conversion relation: For b = 1, lateral velocity variations are caused by thermal effects alone; while b < 1 indicates a decreasing contribution of thermal effects; eventually when b = 0, there is no lateral viscosity variations exist and the Earth is laterally homogeneous. The value of b in the upper mantle is b1 while that in the lower mantle is b2. The lateral viscosity variations computed this way are superposed on a reference model that is able to give a reasonably good fit to the GIA observations. The parameter space for (b1, b2) is then searched to find the combination that yields the best improvement in fitting the GIA data in Laurentide, Fennoscandia or globally.

Compositional analyses of small lunar pyroclastic deposits using Clementine multispectral data

USGS Publications Warehouse

Gaddis, L.R.; Hawke, B.R.; Robinson, M.S.; Coombs, C.

2000-01-01

Clementine ultraviolet-visible (UVVIS) data are used to examine the compositions of 18 pyroclastic deposits (15 small, three large) at 13 sites on the Moon. Compositional variations among pyroclastic deposits largely result from differing amounts of new basaltic (or juvenile) material and reworked local material entrained in their ejecta upon eruption. Characterization of pyroclastic deposit compositions allows us to understand the mechanisms of lunar explosive volcanism. Evidence for compositional differences between small pyroclastic deposits at a single site is observed at Atlas crater. At all sites, compositional variation among the small pyroclastic deposits is consistent with earlier classification based on Earth-based spectra: three compositional groups can be observed, and the trend of increasing mafic absorption band strength from Group 1 to Group 2 to Group 3 is noted. As redefined here, Group 1 deposits include those of Alphonsus West, Alphonsus Southeast, Alphonsus Northeast 2, Atlas South, Crüger, Franklin, Grimaldi, Lavoisier, Oppenheimer, Orientale, and Riccioli. Group 1 deposits resemble lunar highlands, with weak mafic bands and relatively high UV/VIS ratios. Group 2 deposits include those of Alphonsus Northeast 1, Atlas North, Eastern Frigoris East and West, and Aristarchus Plateau; Group 2 deposits are similar to mature lunar maria, with moderate mafic band depths and intermediate UV/VIS ratios. The single Group 3 deposit, J. Herschel, has a relatively strong mafic band and a low UV/VIS ratio, and olivine is a likely juvenile component. Two of the deposits in these groups, Orientale and Aristarchus, are large pyroclastic deposits. The third large pyroclastic deposit, Apollo 17/Taurus Littrow, has a very weak mafic band and a high UV/VIS ratio and it does not belong to any of the compositional groups for small pyroclastic deposits. The observed compositional variations indicate that highland and mare materials are also present in many large and

Towards understanding of the spatio-temporal composition of Terrestrial Water Storage variations in Northern Latitudes using a model-data fusion approach

NASA Astrophysics Data System (ADS)

Trautmann, Tina; Koirala, Sujan; Carvalhais, Nuno; Niemann, Christoph; Fink, Manfred; Jung, Martin

2017-04-01

Understanding variations in the terrestrial water storage (TWS) and its components is essential to gain insights into the dynamics of the hydrological cycle, and to assess temporal and spatial variations of water availability under global changes. We investigated spatio-temporal patterns of TWS variations and their composition in the humid regions of northern mid-to-high latitudes during 2001-2014 by using a simple hydrological model with few effective parameters. Compared to traditional modelling studies, our simple model was informed and constrained by multiple state-of-the-art earth observation products including TWS from Gravity Recovery and Climate Experiment (GRACE) satellites (Wiese 2015), Snow Water Equivalent (SWE) from GlobSnow project (Loujous et al. 2014), evapotranspiration fluxes from eddy covariance measurements (Tramontana et al. 2016), and gridded runoff estimates for Europe (Gudmundsson & Seneviratne 2016). Thorough evaluation of model demonstrates that the model reproduces the observed patterns of hydrological fluxes and states well. The validated model results are then used to assess the contributions of snow pack, soil moisture and groundwater on the integrated TWS across spatial (local grid scale, spatially integrated) and temporal (seasonal, inter-annual) scales. Interestingly, our results show that TWS variations on different scales are dominated by different components. On both, seasonal and inter-annual time scales, the spatially integrated TWS signal mainly originates from dynamics of snow pack. On the local grid scale, mean seasonal TWS variations are driven by snow dynamics as well, whereas inter-annual variations are found to originate from soil moisture availability. Thus, we show that the determinants of TWS variations are scale-dependent, while coincidently underline the potential of model-data fusion techniques to gain insights into the complex hydrological system. References: Gudmundsson, L. and S. I. Seneviratne (2016

Seasonal Variations in Water Chemistry and Sediment Composition in Three Minnesota Lakes

NASA Astrophysics Data System (ADS)

Lascu, I.; Ito, E.; Banerjee, S.

2006-12-01

Variations in water chemistry, isotopic composition of dissolved inorganic carbon, sediment geochemistry and mineral magnetism were monitored for several months in three Minnesota lakes. Lake McCarrons, Deming Lake and Steel Lake are all small (<1 km2), deep (>16 m), stratified lakes that contain varved sediments for some time intervals or throughout. Deming Lake and Steel Lake are situated in north-central Minnesota, about 40 km apart, while Lake McCarrons is located in the heart of the Twin Cities and is heavily used for recreational purposes. The lakes have different mixing regimes (Steel is dimictic, Deming is meromictic and McCarrons is oligomictic) but all have well defined epilimnia and hypolimnia during the ice-free season. Water samples were collected bi-weekly from the epilimnia, upper and lower hypolimnia, while sediments were collected monthly from sediment traps placed in shallow and deep parts of the lakes. All lakes are moderately alkaline (80-280 ppm HCO3-) carbonate-producing systems, although calcite is being dissolved in the slightly acidic hypolimnetic waters of Deming Lake. The magnetic parameters reveal different distributions of the magnetic components in the three lakes, but all exhibit a general increase in the concentration of bacterial magnetosomes towards the end of summer. Differences in elemental concentrations, cation and anion profiles, and chemical behavior as the season progressed are also obvious among the three lakes. For the two lakes situated in the same climatic regime, this implies additional controls (besides climate) on water and sediment composition, such as local hydrology, substrate composition and biogeochemical in-lake processes.

An investigation of interurban variations in the chemical composition and mutagenic activity of airborne particulate organic matter using an integrated chemical class/bioassay system

NASA Astrophysics Data System (ADS)

Butler, J. P.; Kneip, T. J.; Daisey, J. M.

Previous investigations in this laboratory have demonstrated that the mutagenic activities of extractable particulate organic matter (EOM) from cities which differ in their principal fuels and meteorology can vary significantly. To gain a better understanding of these interurban variations, an Integrated Chemical Class/Biological Screening System was developed and used for a more detailed examination of differences in the chemical composition and mutagenic activity of EOM. The screening system involved coupling in situ Ames mutagenicity determinations on high performance thin layer chromatography (HPTLC) plates with class specific chemical analyses on a second set of plates. The system was used to screen for mutagenic activity and selected chemical classes (including PAH, nitro-PAH, phenols, carboxylic acids, carbonyls, aza-arenes and alkylating agents) in EOM from the following sites: New York City; Elizabeth, N.J.; Mexico City; Beijing, China; Philadelphia, PA; and the Caldecott Tunnel (CA). The results of this study demonstrated mutagenic activity and chemical compositional differences in HPTLC subfractions of particulate organic matter from these cities and from the Caldecott Tunnel. The greatest interurban differences in chemical classes were observed for the phenols, carbonyl compounds and alkylating agents. Interurban variations in mutagenic activities were greatest for EOM subfractions of intermediate polarity. These differences are probably related to interurban differences in the fuels used, types of sources and atmospheric conditions. The relationships between these variables are not well understood at present.

Interpopulational and seasonal variation in the chemical signals of the lizard Gallotia galloti.

PubMed

García-Roa, Roberto; Megía-Palma, Rodrigo; Ortega, Jesús; Jara, Manuel; López, Pilar; Martín, José

2017-01-01

Communicative traits are strikingly diverse and may vary among populations of the same species. Within a population, these traits may also display seasonal variation. Chemical signals play a key role in the communication of many taxa. However, we still know far too little about chemical communication in some vertebrate groups. In lizards, only a few studies have examined interpopulational variation in the composition of chemical cues and signals and only one study has explored the seasonal effects. Here we sampled three subspecies of the Tenerife lizards ( Gallotia galloti ) and analyze the lipophilic fraction of their femoral gland secretions to characterize the potential interpopulational variation in the chemical signals. In addition, we assessed whether composition of these secretions differed between the reproductive and the non-reproductive season. We analyzed variations in both the overall chemical profile and the abundance of the two main compounds (cholesterol and vitamin E). Our results show interpopulational and seasonal differences in G. gallotia chemical profiles. These findings are in accordance with the high interpopulational variability of compounds observed in lizard chemical signals and show that their composition is not only shaped by selective factors linked to reproductive season.

Regional variation in tissue composition and biomechanical properties of postmenopausal ovine and human vagina.

PubMed

Ulrich, Daniela; Edwards, Sharon L; Letouzey, Vincent; Su, Kai; White, Jacinta F; Rosamilia, Anna; Gargett, Caroline E; Werkmeister, Jerome A

2014-01-01

There are increasing numbers of reports describing human vaginal tissue composition in women with and without pelvic organ prolapse with conflicting results. The aim of this study was to compare ovine and human posterior vaginal tissue in terms of histological and biochemical tissue composition and to assess passive biomechanical properties of ovine vagina to further characterise this animal model for pelvic organ prolapse research. Vaginal tissue was collected from ovariectomised sheep (n = 6) and from postmenopausal women (n = 7) from the proximal, middle and distal thirds. Tissue histology was analyzed using Masson's Trichrome staining; total collagen was quantified by hydroxyproline assays, collagen III/I+III ratios by delayed reduction SDS PAGE, glycosaminoglycans by dimethylmethylene blue assay, and elastic tissue associated proteins (ETAP) by amino acid analysis. Young's modulus, maximum stress/strain, and permanent strain following cyclic loading were determined in ovine vagina. Both sheep and human vaginal tissue showed comparable tissue composition. Ovine vaginal tissue showed significantly higher total collagen and glycosaminoglycan values (p<0.05) nearest the cervix. No significant differences were found along the length of the human vagina for collagen, GAG or ETAP content. The proximal region was the stiffest (Young's modulus, p<0.05), strongest (maximum stress, p<0.05) compared to distal region, and most elastic (permanent strain). Sheep tissue composition and mechanical properties showed regional differences along the postmenopausal vaginal wall not apparent in human vagina, although the absolute content of proteins were similar. Knowledge of this baseline variation in the composition and mechanical properties of the vaginal wall will assist future studies using sheep as a model for vaginal surgery.

Genetic variation of six desaturase genes in flax and their impact on fatty acid composition.

PubMed

Thambugala, Dinushika; Duguid, Scott; Loewen, Evelyn; Rowland, Gordon; Booker, Helen; You, Frank M; Cloutier, Sylvie

2013-10-01

Flax (Linum usitatissimum L.) is one of the richest plant sources of omega-3 fatty acids praised for their health benefits. In this study, the extent of the genetic variability of genes encoding stearoyl-ACP desaturase (SAD), and fatty acid desaturase 2 (FAD2) and 3 (FAD3) was determined by sequencing the six paralogous genes from 120 flax accessions representing a broad range of germplasm including some EMS mutant lines. A total of 6 alleles for sad1 and sad2, 21 for fad2a, 5 for fad2b, 15 for fad3a and 18 for fad3b were identified. Deduced amino acid sequences of the alleles predicted 4, 2, 3, 4, 6 and 7 isoforms, respectively. Allele frequencies varied greatly across genes. Fad3a, with 110 SNPs and 19 indels, and fad3b, with 50 SNPs and 5 indels, showed the highest levels of genetic variations. While most of the SNPs and all the indels were silent mutations, both genes carried nonsense SNP mutations resulting in premature stop codons, a feature not observed in sad and fad2 genes. Some alleles and isoforms discovered in induced mutant lines were absent in the natural germplasm. Correlation of these genotypic data with fatty acid composition data of 120 flax accessions phenotyped in six field experiments revealed statistically significant effects of some of the SAD and FAD isoforms on fatty acid composition, oil content and iodine value. The novel allelic variants and isoforms identified for the six desaturases will be a resource for the development of oilseed flax with unique and useful fatty acid profiles.

Variation of mechanical behavior of β-TCP/collagen two phase composite scaffold with mesenchymal stem cell in vitro.

PubMed

Arahira, Takaaki; Todo, Mitsugu

2016-08-01

The primary aim of this study is to characterize the variational behavior of the compressive mechanical property of bioceramic-based scaffolds using stem cells during the cell culture period. β-Tricalcium phosphate (TCP)/collagen two phase composites and β-TCP scaffolds were fabricated using the polyurethane template technique and a subsequent freeze-drying method. Rat bone-marrow mesenchymal stem cells (rMSCs) were then cultured in these scaffolds for up to 28 days. Compression tests of the scaffolds with rMSCs were periodically conducted. Biological properties, such as the cell number, alkaline phosphatase (ALP) activity, and gene expressions of osteogenesis, were evaluated. The microstructural change due to cell growth and the formation of extracellular matrices was examined using a field-emission scanning electron microscope. The compressive property was then correlated with the biological properties and microstructures to understand the mechanism of the variational behavior of the macroscopic mechanical property. The porous collagen structure in the β-TCP scaffold effectively improved the structural stability of the composite scaffold, whereas the β-TCP scaffold exhibited structural instability with the collapse of the porous structure when immersed in a culture medium. The β-TCP/collagen composite scaffold exhibited higher ALP activity and more active generation of osteoblastic markers than the β-TCP scaffold. Copyright © 2016 Elsevier Ltd. All rights reserved.

Evaluation of Two Methods for Modeling Measurement Errors When Testing Interaction Effects with Observed Composite Scores

ERIC Educational Resources Information Center

Hsiao, Yu-Yu; Kwok, Oi-Man; Lai, Mark H. C.

2018-01-01

Path models with observed composites based on multiple items (e.g., mean or sum score of the items) are commonly used to test interaction effects. Under this practice, researchers generally assume that the observed composites are measured without errors. In this study, we reviewed and evaluated two alternative methods within the structural…

Observation of pressure variation in the cavitation region of submerged journal bearings

NASA Technical Reports Server (NTRS)

Etsion, I.; Ludwig, L. P.

1980-01-01

Visual observations and pressure measurements in the cavitation zone of a submerged journal bearing are described. Tests were performed at various shaft speeds and ambient pressure levels. Some photographs of the cavitation region are presented showing strong reverse flow at the downstream end of the region. Pressure profiles are presented showing significant pressure variations inside the cavitation zone, contrary to common assumptions of constant cavitation pressure.

The effect of occupational and workplace gender composition on sickness absence.

PubMed

Laaksonen, Mikko; Martikainen, Pekka; Rahkonen, Ossi; Lahelma, Eero

2012-02-01

To examine whether gender composition of the occupation or the workplace is associated with sickness absence, whether the gender composition accounts for the observed female excess in sickness absence, and whether gender composition explains variation in sickness absence rates between occupations and workplaces. Random effects models conducted among Helsinki employees (N = 36,395). Women and men working in women-dominated occupations and workplaces had more short-term (1 to 3 days') sickness absence. Gender composition of the occupation and the workplace partly explained gender differences in short-term but not in intermediate (4 to 14 days') and long-term (>2 weeks') absence. Gender composition also explained variation in short-term sickness absence among occupations and workplaces, but this was partly accounted for by social class, income, and job contract type. The results are consistent with the assumption that short-term sickness absence reflects cultures and norms shaping sickness absence behavior.

Diurnal variations in optical depth at Mars: Observations and interpretations

NASA Technical Reports Server (NTRS)

Colburn, D. S.; Pollack, J. B.; Haberle, R. M.

1988-01-01

Viking lander camera images of the Sun were used to compute atmospheric optical depth at two sites over a period of 1 to 1/3 martian years. The complete set of 1044 optical depth determinations is presented in graphical and tabular form. Error estimates are presented in detail. Optical depths in the morning (AM) are generally larger than in the afternoon (PM). The AM-PM differences are ascribed to condensation of water vapor into atmospheric ice aerosols at night and their evaporation in midday. A smoothed time series of these differences shows several seasonal peaks. These are simulated using a one-dimensional radiative convective model which predicts martial atmospheric temperature profiles. A calculation combining these profiles with water vapor measurements from the Mars Atmospheric Water Detector is used to predict when the diurnal variations of water condensation should occur. The model reproduces a majority of the observed peaks and shows the factors influencing the process. Diurnal variation of condensation is shown to peak when the latitude and season combine to warm the atmosphere to the optimum temperature, cool enough to condense vapor at night and warm enough to cause evaporation at midday.

Argania spinosa var. mutica and var. apiculata: variation of fatty-acid composition, phenolic content, and antioxidant and α-amylase-inhibitory activities among varieties, organs, and development stages.

PubMed

El Adib, Saifeddine; Aissi, Oumayma; Charrouf, Zoubida; Ben Jeddi, Fayçal; Messaoud, Chokri

2015-09-01

Argania spinosa includes two varieties, var. apiculata and var. mutica. These argan varieties were introduced into Tunisia in ancient times and are actually cultivated in some botanic gardens. Little is known about the chemical differentiation among these argan varieties. Hence, the aim of this study was to determine the fatty-acid composition, the total phenolic and flavonoid contents, and the antioxidant and α-amylase-inhibitory activities of leaf, seed, and pulp extracts of both argan varieties harvested during the months of January to April. The fatty-acid distribution was found to depend on the argan variety, the plant organ, and the harvest time. Significant variations in the phenolic contents were observed between the investigated varieties as well as between leaves, pulps, and seeds of each variety. As expected, phenolic compounds were found to be contributors to the antioxidant and α-amylase-inhibitory activities of both argan varieties. The chemical differentiation observed among the two argan varieties, based mainly on the fatty-acid composition, might have some chemotaxonomic value. Copyright © 2015 Verlag Helvetica Chimica Acta AG, Zürich.

Substorm variations in the magnitude of the magnetic field - AMPTE/CCE observations

NASA Technical Reports Server (NTRS)

Lopez, R. E.; Sibeck, D. G.; Lui, A. T. Y.; Takahashi, K.; Mcentire, R. W.

1988-01-01

Using energetic-particle data taken in the near-earth tail by the AMPTE/Charge Composition Explorer (CCE) satellite, 167 ion injection events, that were essentially dispersionless over a 25-285 keV energy range, were identified, and the variations in the total magnetic field strength over the course of these events were examined in order to determine the dependence of the magnetic field strength on dipole latitude. Results indicate that, during periods of substorm activity, the latitudinal position of the current sheet varied significantly within the 32-deg wedge centered on the dipole equator traversed by CCE. Results also suggest that, even in the near-earth magnetotail out to 8.8 R(E) (CCE apogee), the local field measurements are a better guide to the determination of satellite's position relative to the current shield during a substorm, than is the magnetic latitude.

Critical periods in the variation in body composition in school children.

PubMed

Cristi-Montero, Carlos; Bresciani, Guilherme; Alvarez, Ana; Arriagada, Valentina; Beneventi, Angelo; Canepa, Valentina; Espinoza, Paula; Parraguez, Melisa; Toledo, Carlos; Valencia, Consuelo; Rodriguez-Rodriguez, Fernando

2014-10-01

To identify critical periods in the variation in body composition during a school year and determine possible causes. A total of 363 boys and girls aged between 10 and 14 years participated in the study. Before and after the Winter Holidays (WIH) and National Holidays (NAH) (July and September, respectively), measurements were taken of body weight, body fat percentage, waist perimeter, time spent on physical activity and hours of sleep in order to determine the variations. The normality of the data was confirmed and the means were compared with an alpha significance level of p<0.05. The school children increased in weight by 600 g and 510 g in the NAH and WIH, respectively (p<0.0001), and their body fat percentage was significantly increased during both periods (0.51%); however, the waist perimeter measurement saw no significant changes. It can also be seen that in NAH physical activity dropped by an important amount (-41 min, p<0.0001), though this did not occur in WIH. A significant increase in hours of sleep was also seen during the two holiday periods (~1 to 2 hours/day). It is concluded that both NAH and WIH can be considered critical periods due to the sharp increase in body weight and body fat percentage in the school children, where a possible cause is the reduction in time spent on physical activity. Copyright AULA MEDICA EDICIONES 2014. Published by AULA MEDICA. All rights reserved.

[Spatio-temporal variation of drought condition during 1961 to 2012 based on composite index of meteorological drought in Altay region, China].

PubMed

Wu, Yan-feng; Bake, Batur; Li, Wei; Wei, Xiao-qin; Wozatihan, Jiayinaguli; Rasulov, Hamid

2015-02-01

Based on the daily meteorological data of seven stations in Altay region, China, this study investigated the temporal ( seasonal, inter-annual and decadal) and spatial variations of drought by using composite index of meteorological drought, as well as trend analysis, M-K abrupt analysis, wavelet analysis and interpolation tools in ArcGIS. The results indicated that the composite index of meteorological drought could reflect the drought condition in Altay region well. Although the frequency and the covered area of both inter-annual and seasonal droughts presented decreasing trends in the recent 52 a, the drought was still serious when considering the annual drought. The frequencies of inter-annual and spring droughts had no abrupt changes, whereas the frequencies of inter-summer, autumn and winter droughts had abrupt changes during the past 52 a. A significant periodic trend was also observed for the frequencies of inter-annual and seasonal droughts. The distribution of frequency and covered area suggested that the conditions of drought were heavily serious in Qinghe County, moderately serious in Altay City, Fuyun County, Buerjin County and Fuhai County, and slightly serious in Habahe County and Jimunai County.

Temporal geochemical variations in lavas from Kīlauea's Pu`u `Ō`ō eruption (1983-2010): Cyclic variations from melting of source heterogeneities

NASA Astrophysics Data System (ADS)

Greene, Andrew R.; Garcia, Michael O.; Pietruszka, Aaron J.; Weis, Dominique; Marske, Jared P.; Vollinger, Michael J.; Eiler, John

2013-11-01

Geochemical time series analysis of lavas from Kīlauea's ongoing Pu`u `Ō`ō eruption chronicle mantle and crustal processes during a single, prolonged (1983 to present) magmatic event, which has shown nearly two-fold variation in lava effusion rates. Here we present an update of our ongoing monitoring of the geochemical variations of Pu`u `Ō`ō lavas for the entire eruption through 2010. Oxygen isotope measurements on Pu`u `Ō`ō lavas show a remarkable range (δ18O values of 4.6-5.6‰), which are interpreted to reflect moderate levels of oxygen isotope exchange with or crustal contamination by hydrothermally altered Kīlauea lavas, probably in the shallow reservoir under the Pu`u `Ō`ō vent. This process has not measurably affected ratios of radiogenic isotope or incompatible trace elements, which are thought to vary due to mantle-derived changes in the composition of the parental magma delivered to the volcano. High-precision Pb and Sr isotopic measurements were performed on lavas erupted at ˜6 month intervals since 1983 to provide insights about melting dynamics and the compositional structure of the Hawaiian plume. The new results show systematic variations of Pb and Sr isotope ratios that continued the long-term compositional trend for Kīlauea until ˜1990. Afterward, Pb isotope ratios show two cycles with ˜10 year periods, whereas the Sr isotope ratios continued to increase until ˜2003 and then shifted toward slightly less radiogenic values. The short-term periodicity of Pb isotope ratios may reflect melt extraction from mantle with a fine-scale pattern of repeating source heterogeneities or strands, which are about 1-3 km in diameter. Over the last 30 years, Pu`u `Ō`ō lavas show 15% and 25% of the known isotopic variation for Kīlauea and Mauna Kea, respectively. This observation illustrates that the dominant time scale of mantle-derived compositional variation for Hawaiian lavas is years to decades.

Time variations in the mechanical characteristics of local crustal segments according to seismic observations

NASA Astrophysics Data System (ADS)

Kocharyan, G. G.; Gamburtseva, N. G.; Sanina, I. A.; Danilova, T. V.; Nesterkina, M. A.; Gorbunova, E. M.; Ivanchenko, G. N.

2011-04-01

The results of the seismic observations made with two different experimental setups are presented. In the first case, the signals produced by underground nuclear explosions at the Semipalatinsk Test Site were measured on a linear profile, which allowed one to definitely outline the areas where the mechanical properties of rocks experienced considerable time variations. In the second case, the waves excited by the open-pit mine blasts recorded at a small-aperture seismic array at the Mikhnevo Geophysical Station (Institute of Geosphere Dynamics, Russian Academy of Sciences) on the East European Platform favored the estimation of variations in the integral characteristics of the seismic path. Measurements in aseismic regions characterized by diverse geological structure and different tectonic conditions revealed similar effects of the strong dependency of seismic parameters on the time of explosions. Here, the variations experienced by the maximum amplitudes of oscillations and irrelevant to seasonal changes or local conditions reached a factor of two. The generic periods of these variations including the distinct annual rhythm are probably the fragments of a lower-frequency process. The obtained results suggest that these variations are due to changes in the stressstrain state of active fault zones, which, in turn, can be associated with the macroscale motion of large blocks triggered by tidal strains, tectonic forces and, possibly, variations in the rate of the Earth's rotation.

An Integrated Global Atmospheric Composition Observing System: Progress and Impediments

NASA Astrophysics Data System (ADS)

Keating, T. J.

2016-12-01

In 2003-2005, a vision of an integrated global observing system for atmospheric composition and air quality emerged through several international forums (IGACO, 2004; GEO, 2005). In the decade since, the potential benefits of such a system for improving our understanding and mitigation of health and climate impacts of air pollution have become clearer and the needs more urgent. Some progress has been made towards the goal: technology has developed, capabilities have been demonstrated, and lessons have been learned. In Europe, the Copernicus Atmospheric Monitoring Service has blazed a trail for other regions to follow. Powerful new components of the emerging global system (e.g. a constellation of geostationary instruments) are expected to come on-line in the near term. But there are important gaps in the emerging system that are likely to keep us from achieving for some time the full benefits that were envisioned more than a decade ago. This presentation will explore the components and benefits of an integrated global observing system for atmospheric composition and air quality, some of the gaps and obstacles that exist in our current capabilities and institutions, and efforts that may be needed to achieve the envisioned system.

Enhanced converse magnetoelectric effect in cylindrical piezoelectric-magnetostrictive composites

NASA Astrophysics Data System (ADS)

Wu, Gaojian; Zhang, Ru; Zhang, Ning

2016-10-01

Enhanced converse magnetoelectric (ME) effect has been experimentally observed in cylindrical PZT-Terfenol-D piezoelectric-magnetostrictive bilayered composites, where the piezoelectric and magnetostrictive components are coupled through normal stresses instead of shear stresses that act in most of previous multiferroic composites. A theoretical model based on elastodynamics analysis has been proposed to describe the frequency response of converse ME effect for axial and radial modes in the bilayered cylindrical composites. The theory shows good agreement with the experimental results. The different variation tendency of resonant converse ME coefficient, as well as different variation rate of resonance frequency with bias magnetic field for axial and radial modes is interpreted in terms of demagnetizing effect. This work is of theoretical and technological significance for the application of converse ME effect as magnetic sensor, transducers, coil-free flux switch, etc.

SABER (TIMED) and MLS (UARS) Temperature Observations of Mesospheric and Stratospheric QBO and Related Tidal Variations

NASA Technical Reports Server (NTRS)

Huang, Frank T.; Mayr, Hans G.; Reber, Carl A.; Russell, James; Mlynczak, Marty; Mengel, John

2006-01-01

More than three years of temperature observations from the SABER (TIMED) and MLS WARS) instruments are analyzed to study the annual and inter-annual variations extending from the stratosphere into the upper mesosphere. The SABER measurements provide data from a wide altitude range (15 to 95 km) for the years 2002 to 2004, while the MLS data were taken in the 16 to 55 km altitude range a decade earlier. Because of the sampling properties of SABER and MLS, the variations with local solar time must be accounted for when estimating the zonal mean variations. An algorithm is thus applied that delineates with Fourier analysis the year-long variations of the migrating tides and zonal mean component. The amplitude of the diurnal tide near the equator shows a strong semiannual periodicity with maxima near equinox, which vary from year to year to indicate the influence from the Quasi-biennial Oscillation (QBO) in the zonal circulation. The zonal mean QBO temperature variations are analyzed over a range of latitudes and altitudes, and the results are presented for latitudes from 48"s to 48"N. New results are obtained for the QBO, especially in the upper stratosphere and mesosphere, and at mid-latitudes. At Equatorial latitudes, the QBO amplitudes show local peaks, albeit small, that occur at different altitudes. From about 20 to 40 km, and within about 15" of the Equator, the amplitudes can approach 3S K for the stratospheric QBO or SQBO. For the mesospheric QBO or MQBO, we find peaks near 70 km, with temperature amplitudes reaching 3.5"K, and near 85 km, the amplitudes approach 2.5OK. Morphologically, the amplitude and phase variations derived from the SABER and MLS measurements are in qualitative agreement. The QBO amplitudes tend to peak at the Equator but then increase again pole-ward of about 15" to 20'. The phase progression with altitude varies more gradually at the Equator than at mid-latitudes. A comparison of the observations with results from the Numerical Spectral

Diurnal observations of HCl altitude variation in the 70-100 km mesosphere of Venus

NASA Astrophysics Data System (ADS)

Sandor, Brad J.; Todd Clancy, R.

2017-07-01

First submm spectroscopic observations of the 625.9 GHz H35Cl absorption lines of the Venus dayside atmosphere were obtained with the James Clerk Maxwell Telescope (JCMT) on March 2, 2013. These data, which support retrieval of HCl altitude distributions in the Venus mesosphere (70-100 km), are presented here and compared with previously reported JCMT observations of Venus nightside HCl (Sandor et al., 2012). The measured dayside profile agrees with that of the nightside, indicating no diurnal variation is present. More specifically, the nightside spectra revealed a secular decrease of upper mesospheric HCl between observations one month apart, at fixed latitude and local time. The dayside profile reported here presents upper mesospheric abundances that are bracketed by the two previously measured nightside profiles, indicating that if diurnal variation is present, it must be weaker than the secular variations occurring at fixed local time. The previous study, which measured nightside HCl abundances above 85 km to be much smaller than predicted from photochemical modeling, suggested a dynamical explanation for the disagreement wherein nightside downwelling associated with the SubSolar to AntiSolar (SSAS) atmospheric circulation might suppress upper mesospheric abundances predicted purely from photochemistry. However a straightforward prediction from the proposed mechanism is that HCl abundance on the dayside, where the SSAS drives upward rather than downward transport should at least agree with, and perhaps exceed that of the photochemical model. The finding that dayside HCl abundance agrees with that of the nightside, hence also is much smaller than that of the model shows the SSAS hypothesis to be incorrect.

Dissecting the IRX-β dust attenuation relation: exploring the physical origin of observed variations in galaxies

NASA Astrophysics Data System (ADS)

Popping, Gergö; Puglisi, Annagrazia; Norman, Colin A.

2017-12-01

The use of ultraviolet (UV) emission as a tracer of galaxy star formation rate (SFR) is hampered by dust obscuration. The empirical relationship between UV-slope, β, and the ratio between far-infrared and UV luminosity, IRX, is commonly employed to account for obscured UV emission. We present a simple model that explores the physical origin of variations in the IRX-β dust attenuation relation. A relative increase in FUV compared to NUV attenuation and an increasing stellar population age cause variations towards red UV-slopes for a fixed IRX. Dust geometry effects (turbulence, dust screen with holes, mixing of stars within the dust screen, two-component dust model) cause variations towards blue UV-slopes. Poor photometric sampling of the UV spectrum causes additional observational variations. We provide an analytic approximation for the IRX-β relation invoking a subset of the explored physical processes (dust type, stellar population age, turbulence). We discuss observed variations in the IRX-β relation for local (sub-galactic scales) and high-redshift (normal and dusty star-forming galaxies, galaxies during the epoch of reionization) galaxies in the context of the physical processes explored in our model. High spatial resolution imaging of the UV and sub-mm emission of galaxies can constrain the IRX-β dust attenuation relation for different galaxy types at different epochs, where different processes causing variations may dominate. These constraints will allow the use of the IRX-β relation to estimate intrinsic SFRs of galaxies, despite the lack of a universal relation.

Observed solar near UV variability: A contribution to variations of the solar constant

NASA Technical Reports Server (NTRS)

London, Julius; Pap, Judit; Rottman, Gary J.

1989-01-01

Continuous Measurements of the Solar UV have been made by an instrument on the Solar Mesosphere Explorer (SME) since October 1981. The results for the wavelength interval 200 to 300 nm show an irradiance decrease to a minimum in early 1987 and a subsequent increase to mid-April 1989. The observed UV changes during part of solar cycles 21 to 22 represent approx. 35 percent (during the decreasing phase) and 25 percent (during the increasing phase) of the observed variations of the solar constant for the same time period as the SME measurements.

Plume composition as observed by the Cassini Ion Neutral Mass Spectrometer

NASA Astrophysics Data System (ADS)

Waite, J. Hunter; Magee, Brian; Yelle, Roger; Cravens, Tom; Luhmann, Janet; McNutt, Ralph; Kasprzak, Wayne; Niemann, Hasso

The gaseous composition as measured by the Cassini Ion Neutral Mass Spectrometer has been used to infer a plume composition composed mainly of water vapor with percentage amounts of carbon dioxide, ammonia, carbon dioxide and/or molecular nitrogen, and smaller amounts of methane, a combination of acetylene, hydrogen cyanide, and ethylene, propene, argon, and other trace organics (benzene, methanol, formaldehyde, etc). High signal to noise values on the fifth Cassini flyby of Enceladus allowed the determination of a D/H ratio in water of 2.9 x 10-4 similar to values observed in Oort cloud comets to date and suggesting some similarities in conditions during formation. The high value of 40 Ar inferred suggests liquid processes in the interior. Earlier measurements and later measurements present some indication of changes in composition with time or encounter conditions that will be emphasized in this presentation.

Using Apollo sites and soils to compositionally ground truth Diviner Lunar Radiometer observations

NASA Astrophysics Data System (ADS)

Greenhagen, B. T.; Lucey, P. G.; Song, E.; Thomas, I. R.; Bowles, N. E.; Donaldson Hanna, K. L.; Foote, E. J.; Paige, D. A.; Allen, C.

2012-12-01

Apollo landing sites and returned soils afford us a unique opportunity to "ground truth" Diviner Lunar Radiometer compositional observations, which are the first global, high resolution, thermal infrared measurements of an airless body. The Moon is the most accessible member of the most abundant class of solar system objects, which includes Mercury, asteroids, and icy satellites. And the Apollo samples returned from the Moon are the only extraterrestrial samples with known spatial context. Here we compare Diviner observations of Apollo landing sites and compositional and spectral laboratory measurements of returned Apollo soils. Diviner, onboard NASA's Lunar Reconnaissance Orbiter, has three spectral channels near 8 μm that were designed to characterize the mid-infrared emissivity maximum known as the Christiansen feature (CF), a well-studied indicator of silicate mineralogy. It has been observed that thermal infrared spectra measured in simulated lunar environment (SLE) are significantly altered from spectra measured under terrestrial or martian conditions, with enhanced CF contrast and shifted CF position relative to other spectral features. Therefore only thermal emission experiments conducted in SLE are directly comparable to Diviner data. With known compositions, Apollo landing sites and soils are important calibration points for the Diviner dataset, which includes all six Apollo sites at approximately 200 m spatial resolution. Differences in measured CFs caused by composition and space weathering are apparent in Diviner data. Analyses of Diviner observations and SLE measurements for a range of Apollo soils show good agreement, while comparisons to thermal reflectance measurements under ambient conditions do not agree well, which underscores the need for SLE measurements and validates our measurement technique. Diviner observations of Apollo landing sites are also correlated with geochemical measurements of Apollo soils from the Lunar Sample Compendium. In

Using Apollo Sites and Soils to Compositionally Ground Truth Diviner Lunar Radiometer Observations

NASA Technical Reports Server (NTRS)

Greenhagen, Benjamin T.; Lucey, P. G.; Song, E.; Thomas, I R.; Bowles, N. E.; DonaldsonHanna, K. L.; Allen, C.; Foote, E. J.; Paige, D .A.

2012-01-01

Apollo landing sites and returned soils afford us a unique opportunity to "ground truth" Diviner Lunar Radiometer compositional observations, which are the first global, high resolution , thermal infrared measurements of an airless body. The Moon is the most accessible member of the most abundant class of solar system objects, which includes Mercury, asteroids, and icy satellites. And the Apollo samples returned from the Moon are the only extraterrestrial samples with known spatial context. Here we compare Diviner observations of Apollo landing sites and compositional and spectral laboratory measurements of returned Apollo soils. Diviner, onboard NASA's Lunar Reconnaissance Orbiter, has three spectral channels near 8 micron that were designed to characterize the mid-infrared emissivity maximum known as the Christiansen feature (CF), a well-studied indicator of silicate mineralogy. It has been observed that thermal infrared spectra measured in simulated lunar environment (SLE) are significantly altered from spectra measured under terrestrial or martian conditions, with enhanced CF contrast and shifted CF position relative to other spectral features. Therefore only thermal emission experiments conducted in SLE are directly comparable to Diviner data. With known compositions, Apollo landing sites and soils are important calibration points for the Diviner dataset, which includes all six Apollo sites at approximately 200 m spatial resolution. Differences in measured CFs caused by composition and space weathering are apparent in Diviner data. Analyses of Diviner observations and SLE measurements for a range of Apollo soils show good agreement, while comparisons to thermal reflectance measurements under ambient conditions do not agree well, which underscores the need for SLE measurements and validates our measurement technique. Diviner observations of Apollo landing sites are also correlated with geochemical measurements of Apollo soils from the Lunar Sample Compendium

Towards retrievals of aerosol chemical composition from satellite observations by POLDER/PARASOL polarimeter

NASA Astrophysics Data System (ADS)

Li, L.; Dubovik, O.; Derimian, Y.; Lapyonok, T.; Schuster, G. L.; Ducos, F.

2016-12-01

The information about composition of aerosols has a great importance for monitoring and understanding of climate and environment dynamics. Such information can be obtained using situ measurements or chemical transport models. However, in situ sampling has limited spatial and temporal coverage, while estimations have large uncertainties. The present work enables the monitoring of aerosol chemical species from space-borne observations, providing observationally-based results with spatial and temporal coverage. Following the ideas of Schuster et al.(2005, 2009, 2016), we retrieve chemical composition directly from remote sensing measurements without intermediate retrieval of the refractive index (in contrast with Schuster's approach). This approach is expected to reduce the influence of modeling uncertainties, and to provide additional constraints in situations where remote sensing observations do not have enough spectral sensitivity to refractive index. One of principal difficulties is the identification of an adequate model for linking refractive index to chemical composition. Therefore, the initial effort of this work has focused on identifying an optimal "chemical composition to refractive index" conversion model. With that purpose, we first tested the retrieval approach using a simplified volume-weighting model and updated by the Maxwell Garnett mixing model. This concept was incorporated into the GRASP algorithm designed to retrieve an extended set of atmospheric parameters from remote sensing observations. Then a series of sensitivity tests using synthetic data of POLDER/PARASOL were conducted, and followed by inversion of real PARASOL observations. The sensitivity tests showed that these two models allow the retrieval to distinguish amongst the assumed chemical species. Results obtained from real PARASOL data demonstrated good agreement with the optical characteristics provided by AERONET (e.g., r2 of AOT 0.9). The obtained patterns of chemical component

Global-scale Observations of the Limb and Disk (GOLD) Mission - Observing Forcing of the Thermosphere-Ionosphere System from Above and Below

NASA Astrophysics Data System (ADS)

Eastes, Richard; McClintock, William; Burns, Alan

2015-04-01

The GOLD mission will provide unprecedented imaging of the Earth’s space environment and its response to forcing from the Sun and the lower atmosphere. The mission will fly a far ultraviolet imaging spectrograph and is scheduled for launch into geostationary (GEO) orbit in October 2017 as a hosted payload on a commercial communications satellite flying over eastern South America. From this vantage point GOLD will repeatedly image the American hemisphere at a thirty-minute cadence. Fundamental parameters that will be derived from these measurements include composition (O/N2) and temperature of the neutral atmosphere on the dayside disk. Imaging of atmospheric composition, at only a daily cadence, has already provided many new insights into the behavior of the Thermosphere-Ionosphere (T-I) system. Combining composition with simultaneous temperature images will provide revolutionary insights into the behavior of the T-I system and its response to external forcing. Since GOLD will repeatedly observe the same geographic locations, it can distinguish between spatial and temporal variations in the TI system caused by geomagnetic storms, variations in solar EUV, and forcing from the lower atmosphere. GOLD’s measurements and observing approach will give the scientific community a new understanding of the T-I system.

Reliability of mercury-in-silastic strain gauge plethysmography curve reading: influence of clinical clues and observer variation.

PubMed

Høyer, Christian; Pavar, Susanne; Pedersen, Begitte H; Biurrun Manresa, José A; Petersen, Lars J

2013-08-01

Mercury-in-silastic strain gauge pletysmography (SGP) is a well-established technique for blood flow and blood pressure measurements. The aim of this study was to examine (i) the possible influence of clinical clues, e.g. the presence of wounds and color changes during blood pressure measurements, and (ii) intra- and inter-observer variation of curve interpretation for segmental blood pressure measurements. A total of 204 patients with known or suspected peripheral arterial disease (PAD) were included in a diagnostic accuracy trial. Toe and ankle pressures were measured in both limbs, and primary observers analyzed a total of 804 pressure curve sets. The SGP curves were later reanalyzed separately by two observers blinded to clinical clues. Intra- and inter-observer agreement was quantified using Cohen's kappa and reliability was quantified using intra-class correlation coefficients, coefficients of variance, and Bland-Altman analysis. There was an overall agreement regarding patient diagnostic classification (PAD/not PAD) in 202/204 (99.0%) for intra-observer (κ = 0.969, p < 0.001), and 201/204 (98.5%) for inter-observer readings (κ = 0.953, p < 0.001). Reliability analysis showed excellent correlation between blinded versus non-blinded and inter-observer readings for determination of absolute segmental pressures (all intraclass correlation coefficients ≥ 0.984). The coefficient of variance for determination of absolute segmental blood pressure ranged from 2.9-3.4% for blinded/non-blinded data and from 3.8-5.0% for inter-observer data. This study shows a low inter-observer variation among experienced laboratory technicians for reading strain gauge curves. The low variation between blinded/non-blinded readings indicates that SGP measurements are minimally biased by clinical clues.

Reliability of laser Doppler flowmetry curve reading for measurement of toe and ankle pressures: intra- and inter-observer variation.

PubMed

Høyer, C; Paludan, J P D; Pavar, S; Biurrun Manresa, J A; Petersen, L J

2014-03-01

To assess the intra- and inter-observer variation in laser Doppler flowmetry curve reading for measurement of toe and ankle pressures. A prospective single blinded diagnostic accuracy study was conducted on 200 patients with known or suspected peripheral arterial disease (PAD), with a total of 760 curve sets produced. The first curve reading for this study was performed by laboratory technologists blinded to clinical clues and previous readings at least 3 months after the primary data sampling. The pressure curves were later reassessed following another period of at least 3 months. Observer agreement in diagnostic classification according to TASC-II criteria was quantified using Cohen's kappa. Reliability was quantified using intra-class correlation coefficients, coefficients of variance, and Bland-Altman analysis. The overall agreement in diagnostic classification (PAD/not PAD) was 173/200 (87%) for intra-observer (κ = .858) and 175/200 (88%) for inter-observer data (κ = .787). Reliability analysis confirmed excellent correlation for both intra- and inter-observer data (ICC all ≥.931). The coefficients of variance ranged from 2.27% to 6.44% for intra-observer and 2.39% to 8.42% for inter-observer data. Subgroup analysis showed lower observer-variation for reading of toe pressures in patients with diabetes and/or chronic kidney disease than patients not diagnosed with these conditions. Bland-Altman plots showed higher variation in toe pressure readings than ankle pressure readings. This study shows substantial intra- and inter-observer agreement in diagnostic classification and reading of absolute pressures when using laboratory technologists as observers. The study emphasises that observer variation for curve reading is an important factor concerning the overall reproducibility of the method. Our data suggest diabetes and chronic kidney disease have an influence on toe pressure reproducibility. Copyright © 2013 European Society for Vascular Surgery. Published

Determination of variations of the solar radius from solar eclipse observations

NASA Technical Reports Server (NTRS)

Sofia, S.; Dunham, D. W.; Fiala, A. D.

1980-01-01

This paper describes the method to determine the solar radius and its variations from observations made during total solar eclipses. In particular, the procedure to correct the spherical moon predictions for the effects of lunar mountains and valleys on the width and location of the path of totality is addressed in detail. The errors affecting this technique are addressed, a summary of the results of its application to three solar eclipses are presented, and the implications of the results on the constancy of the solar constant are described.

Composite Overwrap Fragmentation Observations, Concerns, and Recommendations

NASA Technical Reports Server (NTRS)

Bangham, Mike; Hovater, Mary

2017-01-01

A series of test activities has raised some concerns about the generation of orbital debris caused by failures of composite overwrapped pressure vessels (COPVs). These tests have indicated that a large number of composite fragments can be produced by either pressure burst failures or by high-speed impacts. A review of prior high-speed tests with COPV indicates that other tests have produced large numbers of composite fragments. As was the case with the test referenced here, the tests tended to produce a large number of small composite fragments with relatively low velocities induced by the impact and or gas expansion.

Time Variations of Observed H α Line Profiles and Precipitation Depths of Nonthermal Electrons in a Solar Flare

DOE Office of Scientific and Technical Information (OSTI.GOV)

Falewicz, Robert; Radziszewski, Krzysztof; Rudawy, Paweł

2017-10-01

We compare time variations of the H α and X-ray emissions observed during the pre-impulsive and impulsive phases of the C1.1-class solar flare on 2013 June 21 with those of plasma parameters and synthesized X-ray emission from a 1D hydrodynamic numerical model of the flare. The numerical model was calculated assuming that the external energy is delivered to the flaring loop by nonthermal electrons (NTEs). The H α spectra and images were obtained using the Multi-channel Subtractive Double Pass spectrograph with a time resolution of 50 ms. The X-ray fluxes and spectra were recorded by RHESSI . Pre-flare geometric andmore » thermodynamic parameters of the model and the delivered energy were estimated using RHESSI data. The time variations of the X-ray light curves in various energy bands and those of the H α intensities and line profiles were well correlated. The timescales of the observed variations agree with the calculated variations of the plasma parameters in the flaring loop footpoints, reflecting the time variations of the vertical extent of the energy deposition layer. Our result shows that the fast time variations of the H α emission of the flaring kernels can be explained by momentary changes of the deposited energy flux and the variations of the penetration depths of the NTEs.« less

Variation of atmospheric carbon monoxide over the Arctic Ocean during summer 2012

NASA Astrophysics Data System (ADS)

Park, Keyhong; Siek Rhee, Tae; Emmons, Louisa

2014-05-01

Atmospheric carbon monoxide (CO) plays an important role in ozone-related chemistry in the troposphere, especially under low-NOx conditions like the open ocean. During summer 2012, we performed a continuous high-resolution (0.1Hz) shipboard measurement of atmospheric CO over the Arctic Ocean. We also simulated the observation using a 3-D global chemical transport model (the Model for OZone And Related chemical Tracers-4; MOZART-4) for further analysis of the observed results. In the model, tags for each sources and emission regions of CO are applied and this enables us to delineate the source composition of the observations. Along with the observed variation of CO concentration during the research cruise, we will present in detailed analysis of the variation of source components and change of regional contributions. We found large (~80ppbv) variation of CO concentration in the Arctic Ocean which is mostly influenced by the variation of biomass burning activity. The contribution of anthropogenic emission is limited over the Arctic Ocean, although the northeast Asian anthropogenic emission shows a dominant component of transported anthropogenic CO. Also, our analysis shows, near the Bering Strait, Europe is the main emission region for anthropogenic CO.

Satellite observed global variations in ecosystem-scale plant water storage

NASA Astrophysics Data System (ADS)

Tian, F.; Wigneron, J. P.; Brandt, M.; Fensholt, R.

2017-12-01

Plant water storage is a key component in ecohydrological processes and tightly coupled with global carbon and energy budgets. Field measurements of individual trees have revealed diurnal and seasonal variations in plant water storage across different tree species and sizes. However, global estimation of plant water storage is challenged by up-scaling from individual trees to an ecosystem scale. The L-band passive microwaves are sensitive to water stored in the stems, branches and leaves, with dependence on the vegetation structure. Thus, the L-band vegetation optical depth (L-VOD) parameter retrieved from satellite passive microwave observations can be used as a proxy for ecosystem-scale plant water storage. Here, we employ the recently developed SMOS (Soil Moisture and Ocean Salinity) L-VOD dataset to investigate spatial patterns in global plant water storage and its diurnal and seasonal variations. In addition, we compare the spatiotemporal patterns between plant water storage and canopy greenness (i.e., enhanced vegetation indices, EVI) to gain ecohydrological insights among different territorial biomes, including boreal forest and tropical woodland. Generally, seasonal dynamics of plant water storage is much smaller than canopy greenness, yet the temporal coupling of these two traits is totally different between boreal and tropical regions, which could be related to their strategies in plant water regulation.

Seasonal variation in kangaroo tooth enamel oxygen and carbon isotopes in southern Australia

NASA Astrophysics Data System (ADS)

Brookman, Tom H.; Ambrose, Stanley H.

2012-09-01

Serial sampling of tooth enamel growth increments for carbon and oxygen isotopic analyses of Macropus (kangaroo) teeth was performed to assess the potential for reconstructing paleoseasonality. The carbon isotope composition of tooth enamel apatite carbonate reflects the proportional intake of C3 and C4 vegetation. The oxygen isotopic composition of enamel reflects that of ingested and metabolic water. Tooth enamel forms sequentially from the tip of the crown to the base, so dietary and environmental changes during the tooth's formation can be detected. δ13C and δ18O values were determined for a series of enamel samples drilled from the 3rd and 4th molars of kangaroos that were collected along a 900 km north-south transect in southern Australia. The serial sampling method did not yield pronounced seasonal isotopic variation patterns in Macropus enamel. The full extent of dietary isotopic variation may be obscured by attenuation of the isotopic signal during enamel mineralisation. Brachydont (low-crowned) Macropus teeth may be less sensitive to seasonal variation in isotopic composition due to time-averaging during mineralisation. However, geographic variations observed suggest that there may be potential for tracking latitudinal shifts in vegetation zones and seasonal environmental patterns in response to climate change.

Lunar atmosphere. How surface composition and meteoroid impacts mediate sodium and potassium in the lunar exosphere.

PubMed

Colaprete, A; Sarantos, M; Wooden, D H; Stubbs, T J; Cook, A M; Shirley, M

2016-01-15

Despite being trace constituents of the lunar exosphere, sodium and potassium are the most readily observed species due to their bright line emission. Measurements of these species by the Ultraviolet and Visible Spectrometer (UVS) on the Lunar Atmosphere and Dust Environment Explorer (LADEE) have revealed unambiguous temporal and spatial variations indicative of a strong role for meteoroid bombardment and surface composition in determining the composition and local time dependence of the Moon's exosphere. Observations show distinct lunar day (monthly) cycles for both species as well as an annual cycle for sodium. The first continuous measurements for potassium show a more repeatable variation across lunations and an enhancement over KREEP (Potassium Rare Earth Elements and Phosphorus) surface regions, revealing a strong dependence on surface composition. Copyright © 2016, American Association for the Advancement of Science.

Habitat-related variation in composition of the essential oil of Seseli rigidum Waldst. & Kit. (Apiaceae).

PubMed

Marčetić, Mirjana; Kovačević, Nada; Lakušić, Dmitar; Lakušić, Branislava

2017-03-01

Plant specialised metabolites like essential oils are highly variable depending on genetic and various ecological factors. The aim of the present work was to characterise essential oils of the species Seseli rigidum Waldst. & Kit. (Apiaceae) in various organs on the individual and populational levels. Geographical variability and the impact of climate and soil type on essential oil composition were also investigated. Individually sampled essential oils of roots, aerial parts and fruits of plants from seven populations were analysed by GC-FID and GC-MS. The investigated populations showed high interpopulational and especially intrapopulational variability of essential oil composition. In regard to the variability of essential oils, different chemotypes were defined. The essential oils of S. rigidum roots represented a falcarinol chemotype, oils of aerial parts constituted an α-pinene or α-pinene/sabinene chemotype and fruit essential oils can be characterised as belonging to a complex sabinene/α-pinene/β-phellandrene/falcarinol/germacrene B chemotype. At the species level, analysis of variance (ANOVA), principal component analysis (PCA) and canonical discriminant analysis (CDA) showed that the plant part exerted the strongest influence on the composition of essential oils. Climate had a high impact on composition of the essential oils of roots, aerial parts and fruits, while influence of the substrate was less pronounced. The variations in main compounds of essential oils based on climate or substrate were complex and specific to the plant part. Copyright © 2016 Elsevier Ltd. All rights reserved.

Ionospheric variation observed in Oregon Real-time GNSS network during the total eclipse of 21 August 2017

NASA Astrophysics Data System (ADS)

Shahbazi, A.; Park, J.; Kim, S.; Oberg, R.

2017-12-01

As the ionospheric behavior is highly related to the solar activity, the total eclipse passing across the North America on 21 August 2017 is expected to significantly affect the electron density in the ionosphere along the path. Taking advantage of GNSS capability for observing total electron content (TEC), this study demonstrates the impact of the total eclipse not only on the TEC variation during the period of the event but also on GNSS positioning. Oregon Department of Transportation (ODOT) runs a dense real time GNSS network, referred to as Oregon Real-time GNSS network (ORGN). From the dual frequency GPS and GLONASS observations in ORGN, the TEC over the network area can be extracted. We observe the vertical TEC (VTEC) from the ORGN for analyzing the ionospheric condition in the local area affected by the eclipse. To observe the temporal variation, we also observe the slant TEC (STEC) in each ray path and analyze the short term variation in different geometry of each ray path. Although the STEC is dependent quantity upon the changing geometry of a satellite, this approach provides insight to the ionospheric behavior of the total eclipse because the STEC does not involve the projection error, which is generated by VTEC computation. During the period of eclipse, the abnormal variations on VTEC and STEC are expected. The experimental results will be presented in time series plots for selected stations as well as the regional TEC map in Oregon. In addition to the TEC monitoring, we also test the positioning result of ORGN stations through Precise Point Positioning (PPP) and relative positioning. The expected result is that the both positioning results are degraded during the solar eclipse due to the instable ionospheric condition over short time.

Ion composition variety and variability around perihelion

NASA Astrophysics Data System (ADS)

Beth, Arnaud; Altwegg, Kathrin; Behar, Étienne; Broiles, Tom; Burch, Jim; Carr, Christopher; Eriksson, Anders; Galand, Marina; Goetz, Charlotte; Henri, Pierre; Heritier, Kévin; Nilsson, Hans; Odelstad, Elias; Richter, Ingo; Rubin, Martin; Vallieres, Xavier

2017-04-01

For two years, the Double Focusing Mass Spectrometer (DFMS), one of the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) onboard Rosetta probed the neutral gas and the plasma composition of the comet 67P/Churyumov-Gerasimenko's coma (67P). Major ion species detected include water ions (e.g, H2O+, H3O+, HO+) observed throughout the escorting phase. The analysis of DFMS data revealed a large zoo of ion species near perihelion (summer 2015). In particular, protonated versions of high proton affinity neutrals (e.g., NH4+) were detected, but also hydrocarbon and organic ion species. Near perihelion, ion composition was also highly variable and showed interesting variations in the complexity of the observed ion species. We will first present an overview of the rich variety of ion species observed during perihelion. This study will be supported by ionospheric modeling of ion composition below the ion exobase. We will then show an intercomparison between DFMS data and Rosetta Plasma Consortium (RPC) plasma and particle data to interpret the DFMS ion composition variability. Our primary goal is to highlight any correlation between observations from these different instruments (i.e. ion composition, ion and electron number density, energy distribution, magnetic field) and to find relevant signatures of physical processes which can affect the chemistry and dynamics (e.g., acceleration and deflection) of the involved neutral and ion species.

Latitudinal Variations In Vertical Cloud Structure Of Jupiter As Determined By Ground- based Observation With Multispectral Imaging

NASA Astrophysics Data System (ADS)

Sato, T.; Kasaba, Y.; Takahashi, Y.; Murata, I.; Uno, T.; Tokimasa, N.; Sakamoto, M.

2008-12-01

We conducted ground-based observation of Jupiter with the liquid crystal tunable filter (LCTF) and EM-CCD camera in two methane absorption bands (700-757nm, 872-950nm at 3 nm step: total of 47 wavelengths) to derive detailed Jupiter's vertical cloud structure. The 2-meter reflector telescope at Nishi-Harima astronomical observatory in Japan was used for our observation on 26-30 May, 2008. After a series of image processing (composition of high quality images in each wavelength and geometry calibration), we converted observed intensity to absolute reflectivity at each pixel using standard star. As a result, we acquired Jupiter's data cubes with high-spatial resolution (about 1") and narrow band imaging (typically 7nm) in each methane absorption band by superimposing 30 Jupiter's images obtained in short exposure time (50 ms per one image). These data sets enable us to probe different altitudes of Jupiter from 100 mbar down to 1bar level with higher vertical resolution than using convectional interference filters. To interpret observed center-limb profiles, we developed radiative transfer code based on layer adding doubling algorithm to treat multiple scattering of solar light theoretically and extracted information on aerosol altitudes and optical properties using two-cloud model. First, we fit 5 different profiles simultaneously in continuum data (745-757 nm) to retrieve information on optical thickness of haze and single scattering albedo of cloud. Second, we fit 15 different profiles around 727nm methane absorption band and 13 different profiles around 890 nm methane absorption band to retrieve information on the aerosol altitude location and optical thickness of cloud. In this presentation, we present the results of these modeling simulations and discuss the latitudinal variations of Jupiter's vertical cloud structure.

Compositional variations of ignimbrite magmas in the Central Andes over the past 26 Ma - A multivariate statistical perspective

NASA Astrophysics Data System (ADS)

Brandmeier, M.; Wörner, G.

2016-10-01

younger (< 10 Ma) Altiplano-Puna-Volcanic-Complex (APVC) ignimbrites that are of similar volumes. Older ignimbrites are less depleted in HREE and less radiogenic in Sr isotopes, indicating smaller crustal contributions during evolution in a thinner and thermally less evolved crust. These compositional variations indicate a relation to crustal thickening with a "transition" from plagioclase to amphibole and garnet residual mineralogy between 13 and 9 Ma. Compositional and volumetric variations correlate to the N-S passage of the Juan-Fernandéz-Ridge, crustal shortening and thickening, and increased average crustal temperatures during the past 26 Ma. Table DR2 Mapped ignimbrite sheets.

Arsenic distribution and valence state variation studied by fast hierarchical length-scale morphological, compositional, and speciation imaging at the Nanoscopium, Synchrotron Soleil

NASA Astrophysics Data System (ADS)

Somogyi, Andrea; Medjoubi, Kadda; Sancho-Tomas, Maria; Visscher, P. T.; Baranton, Gil; Philippot, Pascal

2017-09-01

The understanding of real complex geological, environmental and geo-biological processes depends increasingly on in-depth non-invasive study of chemical composition and morphology. In this paper we used scanning hard X-ray nanoprobe techniques in order to study the elemental composition, morphology and As speciation in complex highly heterogeneous geological samples. Multivariate statistical analytical techniques, such as principal component analysis and clustering were used for data interpretation. These measurements revealed the quantitative and valance state inhomogeneity of As and its relation to the total compositional and morphological variation of the sample at sub-μm scales.

Season affects body composition and estimation of fluid overload in haemodialysis patients: variations in body composition; a survey from the European MONDO database.

PubMed

Broers, Natascha J H; Usvyat, Len A; Marcelli, Daniele; Bayh, Inga; Scatizzi, Laura; Canaud, Bernard; van der Sande, Frank M; Kotanko, Peter; Moissl, Ulrich; Kooman, Jeroen P

2015-04-01

Seasonal variations in blood pressure (BP) and inter-dialytic weight gain (IDWG) are well established in dialysis patients. However, no study has assessed changes in body composition (BC) in this population. In this survey, seasonal variations in fat mass (FM), lean tissue mass (LTM), extracellular water (ECW) and fluid overload (FO) were assessed in 42 099 dialysis patients (mean age 61.2 years, 58% males) from the Fresenius Medical Care Europe database, as part of the MONitoring Dialysis Outcomes (MONDO) consortium, in relation to other nutritional parameters, IDWG and BP. BC was assessed by a body composition monitor (BCM®, Fresenius Medical Care, Bad Homburg, Germany). FM was highest in winter and lowest in summer (▵FM -1.17 kg; P < 0.001), whereas LTM was lowest during winter and highest in summer (▵LTM 0.86 kg; P < 0.0001). ECW and FO were lowest in winter, and highest in spring (▵ECW: 0.13 L; P < 0.0001, ▵FO: 0.31 L; P < 0.0001) and summer (▵ECW: 0.15 L; P < 0.0001 and ▵FO: 0.2 L; P < 0.0001), despite a higher systolic blood pressure (SBP; 136.7 ± 17.4 mmHg) and IDWG (3.0 ± 1.1 kg) during winter. C-reactive protein (CRP), serum sodium and haemoglobin levels were highest in winter, whereas serum albumin was lowest in fall. Normalized protein catabolic rate (nPCR) was lowest in winter and matched variations in BC only to a minor degree. BC and hydration state, assessed by bio-impedance spectroscopy, follows a seasonal pattern which may be of relevance for the estimation of target weight, and for the interpretation of longitudinal studies including estimates of BC. Whether these changes should lead to therapeutic interventions could be the focus of future studies. © The Author 2014. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved.

Compositional Stability of the Bacterial Community in a Climate-Sensitive Sub-Arctic Peatland

PubMed Central

Weedon, James T.; Kowalchuk, George A.; Aerts, Rien; Freriks, Stef; Röling, Wilfred F. M.; van Bodegom, Peter M.

2017-01-01

The climate sensitivity of microbe-mediated soil processes such as carbon and nitrogen cycling offers an interesting case for evaluating the corresponding sensitivity of microbial community composition to environmental change. Better understanding of the degree of linkage between functional and compositional stability would contribute to ongoing efforts to build mechanistic models aiming at predicting rates of microbe-mediated processes. We used an amplicon sequencing approach to test if previously observed large effects of experimental soil warming on C and N cycle fluxes (50–100% increases) in a sub-arctic Sphagnum peatland were reflected in changes in the composition of the soil bacterial community. We found that treatments that previously induced changes to fluxes did not associate with changes in the phylogenetic composition of the soil bacterial community. For both DNA- and RNA-based analyses, variation in bacterial communities could be explained by the hierarchy: spatial variation (12–15% of variance explained) > temporal variation (7–11%) > climate treatment (4–9%). We conclude that the bacterial community in this environment is stable under changing conditions, despite the previously observed sensitivity of process rates—evidence that microbe-mediated soil processes can alter without concomitant changes in bacterial communities. We propose that progress in linking soil microbial communities to ecosystem processes can be advanced by further investigating the relative importance of community composition effects versus physico-chemical factors in controlling biogeochemical process rates in different contexts. PMID:28326062

Compositional Stability of the Bacterial Community in a Climate-Sensitive Sub-Arctic Peatland.

PubMed

Weedon, James T; Kowalchuk, George A; Aerts, Rien; Freriks, Stef; Röling, Wilfred F M; van Bodegom, Peter M

2017-01-01

The climate sensitivity of microbe-mediated soil processes such as carbon and nitrogen cycling offers an interesting case for evaluating the corresponding sensitivity of microbial community composition to environmental change. Better understanding of the degree of linkage between functional and compositional stability would contribute to ongoing efforts to build mechanistic models aiming at predicting rates of microbe-mediated processes. We used an amplicon sequencing approach to test if previously observed large effects of experimental soil warming on C and N cycle fluxes (50-100% increases) in a sub-arctic Sphagnum peatland were reflected in changes in the composition of the soil bacterial community. We found that treatments that previously induced changes to fluxes did not associate with changes in the phylogenetic composition of the soil bacterial community. For both DNA- and RNA-based analyses, variation in bacterial communities could be explained by the hierarchy: spatial variation (12-15% of variance explained) > temporal variation (7-11%) > climate treatment (4-9%). We conclude that the bacterial community in this environment is stable under changing conditions, despite the previously observed sensitivity of process rates-evidence that microbe-mediated soil processes can alter without concomitant changes in bacterial communities. We propose that progress in linking soil microbial communities to ecosystem processes can be advanced by further investigating the relative importance of community composition effects versus physico-chemical factors in controlling biogeochemical process rates in different contexts.

Spatio-temporal variation of methane over Indian region: Seasonal and inter-annual variation .

NASA Astrophysics Data System (ADS)

M, K.; Nair, P. R.

2015-12-01

Methane (CH4) has an important role in the radiation budget and chemistry in the lower and middle atmosphere as a greenhouse and reactive trace gas. The rapid developments in the agriculture and industry over India have lead to the emission of many pollutants like CO, O3, CH4, CO2, SO2 etc into the atmosphere. However, their sources, sinks and concentration levels are poorly understood because of the lack of systematic sampling and monitoring. The advent of satellite remote sensing has helped to analyze the chemical composition of atmosphere with good spatial coverage especially over tropical region which was poorly sampled with the existing surface network. This work attempts an analysis of spatial distribution, seasonal cycle and inter annual variation of CH4 over Indian region during 2003-2009 using SCIAMACHY data onboard ENVISAT. Column CH4 varies from 1740-1890 ppbv over Indian region with distinct spatial and temporal features. We observed a dependence of seasonal CH4 variation on rice cultivation, convective activities and changes in boundary layer characteristics. The comparative study using satellite, aircraft and surface measurement shown CH4 has non-homogeneity in its distribution and seasonal variation in different layers of atmosphere. A comparative study of CH4 at different hot spot regions over the globe was carried out which showed prominent hemispherical variations. Large spread in column CH4 was observed at India and Chinese region compared to other regions with a significant seasonal variability. This study points to the blending of satellite, aircraft and surface measurements for the realization of regional distribution of CH4.

Diurnal Variation in Gravity Wave Activity at Low and Middle Latitudes

NASA Technical Reports Server (NTRS)

Andrioli, V. F.; Fritts, D. C.; Batista, P. P.; Clemesha, B. R.; Janches, Diego

2013-01-01

We employ a modified composite day extension of the Hocking (2005) analysis method to study gravity wave (GW) activity in the mesosphere and lower thermosphere using 4 meteor radars spanning latitudes from 7deg S to 53.6deg S. Diurnal and semidiurnal modulations were observed in GW variances over all sites. Semidiurnal modulation with downward phase propagation was observed at lower latitudes mainly near the equinoxes. Diurnal modulations occur mainly near solstice and, except for the zonal component at Cariri (7deg S), do not exhibit downward phase propagation. At a higher latitude (SAAMER, 53.6deg S) these modulations are only observed in the meridional component where we can observe diurnal variation from March to May, and semidiurnal, during January, February, October (above 88 km) and November. Some of these modulations with downward phase progression correlate well with wind shear. When the wind shear is well correlated with the maximum of the variances the diurnal tide has its largest amplitudes, i.e., near equinox. Correlations exhibiting variations with tidal phases suggest significant GW-tidal interactions that have different characters depending on the tidal components and possible mean wind shears. Modulations that do not exhibit phase variations could be indicative of diurnal variations in GW sources.

Generalized Dissimilarity Modeling of Late-Quaternary Variations in Pollen-Based Compositional Dissimilarity

NASA Astrophysics Data System (ADS)

Williams, J. W.; Blois, J.; Ferrier, S.; Manion, G.; Fitzpatrick, M.; Veloz, S.; He, F.; Liu, Z.; Otto-Bliesner, B. L.

2011-12-01

In Quaternary paleoecology and paleoclimatology, compositionally dissimilar fossil assemblages usually indicate dissimilar environments; this relationship underpins assemblage-level techniques for paleoenvironmental reconstruction such as mutual climatic ranges or the modern analog technique. However, there has been relatively little investigation into the form of the relationship between compositional dissimilarity and climatic dissimilarity. Here we apply generalized dissimilarity modeling (GDM; Ferrier et al. 2007) as a tool for modeling the expected non-linear relationships between compositional and climatic dissimilarity. We use the CCSM3.0 transient paleoclimatic simulations from the SynTrace working group (Liu et al. 2009) and a new generation of fossil pollen maps from eastern North America (Blois et al. 2011) to 1) assess the spatial relationships between compositional dissimilarity and climatic dissimilarity and 2) whether these spatial relationships change over time. We used a taxonomic list of 106 genus-level pollen types, six climatic variables (winter precipitation and mean temperature, summer precipitation and temperature, seasonality of precipitation, and seasonality of temperature) that were chosen to minimize collinearity, and a cross-referenced pollen and climate dataset mapped for time slices spaced 1000 years apart. When GDM was trained for one time slice, the correlation between predicted and observed spatial patterns of community dissimilarity for other times ranged between 0.3 and 0.73. The selection of climatic predictor variables changed over time, as did the form of the relationship between compositional turnover and climatic predictors. Summer temperature was the only variable selected for all time periods. These results thus suggest that the relationship between compositional dissimilarity in pollen assemblages (and, by implication, beta diversity in plant communities) and climatic dissimilarity can change over time, for reasons to be

Carbon Observations from Geostationary Earth Orbit as Part of an Integrated Observing System for Atmospheric Composition

NASA Astrophysics Data System (ADS)

Edwards, D. P.

2015-12-01

This presentation describes proposed satellite carbon measurements from the CHRONOS mission. The primary goal of this experiment is to measure the atmospheric pollutants carbon monoxide (CO) and methane (CH4) from geostationary orbit, with hourly observations of North America at high spatial resolution. CHRONOS observations would provide measurements not currently available or planned as part of a surface, suborbital and satellite integrated observing system for atmospheric composition over North America. Carbon monoxide is produced by combustion processes such as urban activity and wildfires, and serves as a proxy for other combustion pollutants that are not easily measured. Methane has diverse anthropogenic sources ranging from fossil fuel production, animal husbandry, agriculture and waste management. The impact of gas exploration in the Western States of the USA and oil extraction from the Canadian tar sands will be particular foci of the mission, as will the poorly-quantified natural CH4 emissions from wetlands and thawing permafrost. In addition to characterizing pollutant sources, improved understanding of the domestic CH4 budget is a priority for policy decisions related to short-lived climate forcers. A primary motivation for targeting CO is its value as a tracer of atmospheric pollution, and CHRONOS measurements will provide insight into local and long-range transport across the North American continent, as well as the processes governing the entrainment and venting of pollution in and out of the planetary boundary layer. As a result of significantly improved characterization of diurnal changes in atmospheric composition, CHRONOS observations will find direct societal applications for air quality regulation and forecasting. We present a quantification of this expected improvement in the prediction of near-surface concentrations when CHRONOS measurements are used in Observation System Simulation Experiments (OSSEs). If CHRONOS and the planned NASA Earth

Apatite in carbonatitic rocks: Compositional variation, zoning, element partitioning and petrogenetic significance

NASA Astrophysics Data System (ADS)

Chakhmouradian, Anton R.; Reguir, Ekaterina P.; Zaitsev, Anatoly N.; Couëslan, Christopher; Xu, Cheng; Kynický, Jindřich; Mumin, A. Hamid; Yang, Panseok

2017-03-01

Apatite-group phosphates are nearly ubiquitous in carbonatites, but our understanding of these minerals is inadequate, particularly in the areas of element partitioning and petrogenetic interpretation of their compositional variation among spatially associated rocks and within individual crystals. In the present work, the mode of occurrence, and major- and trace-element chemistry of apatite (sensu lato) from calcite and dolomite carbonatites, their associated cumulate rocks (including phoscorites) and hydrothermal parageneses were studied using a set of 80 samples from 50 localities worldwide. The majority of this set represents material for which no analytical data are available in the literature. Electron-microprobe and laser-ablation mass-spectrometry data ( 600 and 400 analyses, respectively), accompanied by back-scattered-electron and cathodoluminescence images and Raman spectra, were used to identify the key compositional characteristics and zoning patterns of carbonatitic apatite. These data are placed in the context of phosphorus geochemistry in carbonatitic systems and carbonatite evolution, and compared to the models proposed by previous workers. The documented variations in apatite morphology and zoning represent a detailed record of a wide range of evolutionary processes, both magmatic and fluid-driven. The majority of igneous apatite from the examined rocks is Cl-poor fluorapatite or F-rich hydroxylapatite (≥ 0.3 apfu F) with 0.2-2.7 wt.% SrO, 0-4.5 wt.% LREE2O3, 0-0.8 wt.% Na2O, and low levels of other cations accommodated in the Ca site (up to 1000 ppm Mn, 2300 ppm Fe, 200 ppm Ba, 150 ppm Pb, 700 ppm Th and 150 ppm U), none of which show meaningful correlation with the host-rock type. Silicate, (SO4)2 - and (VO4)3 - anions, substituting for (PO4)3 -, tend to occur in greater abundance in crystals from calcite carbonatites (up to 4.2 wt.% SiO2, 1.5 wt.% SO3 and 660 ppm V). Although (CO3)2 - groups are very likely present in some samples, Raman micro

Does stability in local community composition depend on temporal variation in rates of dispersal and connectivity?

NASA Astrophysics Data System (ADS)

Valanko, Sebastian; Norkko, Joanna; Norkko, Alf

2015-04-01

In ecology understanding variation in connectivity is central for how biodiversity is maintained. Field studies on dispersal and temporal dynamics in community regulating processes are, however, rare. We test the short-term temporal stability in community composition in a soft-sediment benthic community by determining among-sampling interval similarity in community composition. We relate stability to in situ measures of connectivity (wind, wave, current energy) and rates of dispersal (quantified in different trap types). Waves were an important predictor of when local community taxa are most likely to disperse in different trap-types, suggesting that wave energy is important for connectivity in a region. Community composition at the site was variable and changed stochastically over time. We found changes in community composition (occurrence, abundance, dominance) to be greater at times when connectivity and rates of dispersal were low. In response to periods of lower connectedness dominant taxa in the local community only exhibited change in their relative abundance. In contrast, locally less abundant taxa varied in both their presence, as well as in relative abundance. Constancy in connectivity and rates of dispersal promotes community stability and persistence, suggesting that local community composition will be impacted by changes in the spatial extent over which immigration and emigration operates in the region. Few empirical studies have actually measured dispersal directly in a multi-species context to demonstrate the role it plays in maintaining local community structure. Even though our study does not evaluate coexistence over demographic time scales, it importantly demonstrates that dispersal is not only important in initial recruitment or following a disturbance, but also key in maintaining local community composition.

Thermal Phase Variations of WASP-12b: Defying Predictions

NASA Technical Reports Server (NTRS)

Cowan, Nicolas B.; Machalek, Pavel; Croll, Bryce; Shekhtman, Louis M.; Burrows, Adam; Deming, Drake; Greene, Tom; Hora, Joseph L.

2012-01-01

We report Warm Spitzer full-orbit phase observations of WASP-12b at 3.6 and 4.5 micrometers. This extremely inflated hot Jupiter is thought to be overflowing its Roche lobe, undergoing mass loss and accretion onto its host star, and has been claimed to have a C/O ratio in excess of unity. We are able to measure the transit depths, eclipse depths, thermal and ellipsoidal phase variations at both wavelengths. The large-amplitude phase variations, combined with the planet's previously measured dayside spectral energy distribution, are indicative of non-zero Bond albedo and very poor day-night heat redistribution. The transit depths in the mid-infrared-(R(sub p)/R(sub *))(sup 2) = 0.0123(3) and 0.0111(3) at 3.6 and 4.5 micrometers, respectively-indicate that the atmospheric opacity is greater at 3.6 than at 4.5 micrometers, in disagreement with model predictions, irrespective of C/O ratio. The secondary eclipse depths are consistent with previous studies: F(sub day)/F(sub *) = 0.0038(4) and 0.0039(3) at 3.6 and 4.5 micrometers, respectively. We do not detect ellipsoidal variations at 3.6 micrometers, but our parameter uncertainties-estimated via prayer-bead Monte Carlo-keep this non-detection consistent with model predictions. At 4.5 micrometers, on the other hand, we detect ellipsoidal variations that are much stronger than predicted. If interpreted as a geometric effect due to the planet's elongated shape, these variations imply a 3:2 ratio for the planet's longest:shortest axes and a relatively bright day-night terminator. If we instead presume that the 4.5 micrometer ellipsoidal variations are due to uncorrected systematic noise and we fix the amplitude of the variations to zero, the best-fit 4.5 micrometer transit depth becomes commensurate with the 3.6 micrometer depth, within the uncertainties. The relative transit depths are then consistent with a solar composition and short scale height at the terminator. Assuming zero ellipsoidal variations also yields a much

Thermal Phase Variations of WASP-12b: Defying Predictions

NASA Astrophysics Data System (ADS)

Cowan, Nicolas B.; Machalek, Pavel; Croll, Bryce; Shekhtman, Louis M.; Burrows, Adam; Deming, Drake; Greene, Tom; Hora, Joseph L.

2012-03-01

We report Warm Spitzer full-orbit phase observations of WASP-12b at 3.6 and 4.5 μm. This extremely inflated hot Jupiter is thought to be overflowing its Roche lobe, undergoing mass loss and accretion onto its host star, and has been claimed to have a C/O ratio in excess of unity. We are able to measure the transit depths, eclipse depths, thermal and ellipsoidal phase variations at both wavelengths. The large-amplitude phase variations, combined with the planet's previously measured dayside spectral energy distribution, are indicative of non-zero Bond albedo and very poor day-night heat redistribution. The transit depths in the mid-infrared—(Rp /R *)2 = 0.0123(3) and 0.0111(3) at 3.6 and 4.5 μm, respectively—indicate that the atmospheric opacity is greater at 3.6 than at 4.5 μm, in disagreement with model predictions, irrespective of C/O ratio. The secondary eclipse depths are consistent with previous studies: F day/F * = 0.0038(4) and 0.0039(3) at 3.6 and 4.5 μm, respectively. We do not detect ellipsoidal variations at 3.6 μm, but our parameter uncertainties—estimated via prayer-bead Monte Carlo—keep this non-detection consistent with model predictions. At 4.5 μm, on the other hand, we detect ellipsoidal variations that are much stronger than predicted. If interpreted as a geometric effect due to the planet's elongated shape, these variations imply a 3:2 ratio for the planet's longest:shortest axes and a relatively bright day-night terminator. If we instead presume that the 4.5 μm ellipsoidal variations are due to uncorrected systematic noise and we fix the amplitude of the variations to zero, the best-fit 4.5 μm transit depth becomes commensurate with the 3.6 μm depth, within the uncertainties. The relative transit depths are then consistent with a solar composition and short scale height at the terminator. Assuming zero ellipsoidal variations also yields a much deeper 4.5 μm eclipse depth, consistent with a solar composition and modest

Seasonal variation in proximate composition and fatty acid profile of grey triggerfish (Balistes capriscus) captured along the coast of Portugal.

PubMed

Simões, Tiago; Carvalho, João; Sousa, Ana; Lemos, Marco F L; Gil, Maria M; Pedrosa, Rui; Tecelão, Carla

2013-05-01

Proximate composition (ash, moisture, total protein, and fat contents) and fatty acid profile of Balistes capriscus (grey triggerfish) were assessed over a 6-months period (April to September, 2011) in animals captured along the coast of Peniche (Portugal). High protein (18.9% to 21.4%) and low lipid (0.5% to 0.8%) contents were determined. The highest lipid level was found in June-captured animals. High proportions of n-3 polyunsaturated fatty acids (n-3 PUFA) were observed (53.87 ± 2.00%) together with substantial quantities of oleic acid (27.58 ± 1.09%) and palmitic acid (16.52 ± 0.93%). Docosahexaenoic acid accounted for 77% of the total PUFA and was 7 times more abundant than eicosapentaenoic acid, and the n-3/n-6 ratio was 7.2. Gender did not influence lipid levels and the fatty acid profile, but seasonal variations were observed for PUFA and monounsaturated fatty acid contents. Overall, the nutritional properties of this underexploited species may be comparable to those of other lean fish species with higher economic value. © 2013 Institute of Food Technologists®

Consequences of the superstrong nature of chalcogenide glass-forming liquids at select compositions

NASA Astrophysics Data System (ADS)

Gunasekera, Kapila; Bhosle, Siddhesh; Boolchand, Punit; Micoulaut, Matthieu

2014-03-01

Growth of homogeneous melts of stoichiometric compositions of chalcogenides is facilitated by underlying crystalline phases. Such is not the case for non-stoichiometric melt compositions in which, for example, variation of fragility (m) from complex specific heat measurements show global minimum at an extremely low value (m =14.8(0.5)) in the 21.5% variation along a quartz tube as a function of reaction time of starting materials at a fixed temperature T>Tg over days, we have observed a slowdown of melt-homogenization by the super-strong melt compositions, 21.5% observed between the ?exible and stressed rigid phase in network glasses. Supported by NSF grant DMR 08-53957.

Effect of seasonal variation on the composition and properties of raw milk destined for processing in the UK.

PubMed

Chen, Biye; Lewis, Michael J; Grandison, Alistair S

2014-09-01

The composition and physical properties of raw milk from a commercial herd were studied over a 1 year period in order to understand how best to utilise milk for processing throughout the year. Protein and fat levels demonstrated seasonal trends, while minerals and many physical properties displayed considerable variations, which were apparently unrelated to season. However, rennet clotting time, ethanol stability and foaming ability were subject to seasonal variation. Many significant interrelationships in physico-chemical properties were found. It is clear that the milk supply may be more suited to the manufacture of different products at different times of the year or even on a day to day basis. Subsequent studies will report on variation in production and quality of products manufactured from the same milk samples described in the current study and will thus highlight potential advantages of seasonal processing of raw milk. Copyright © 2014 Elsevier Ltd. All rights reserved.

Observation of spatial and temporal variations in X-ray bright point emergence patterns. [at solar surface

NASA Technical Reports Server (NTRS)

Golub, L.; Krieger, A. S.; Vaiana, G. S.

1976-01-01

Observations of X-ray bright points (XBP) over a six-month interval in 1973 show significant variations in both the number density of XBP as a function of heliographic longitude and in the full-sun average number of XBP from one rotation to the next. The observed increases in XBP emergence are estimated to be equivalent to several large active regions emerging per day for several months. The number of XBP emerging at high latitudes varies in phase with the low-latitude variation and reaches a maximum approximately simultaneous with a major outbreak of active regions. The quantity of magnetic flux emerging in the form of XBP at high latitudes alone is estimated to be as large as the contribution from all active regions.

Bayesian Analysis of Hmi Images and Comparison to Tsi Variations and MWO Image Observables

NASA Astrophysics Data System (ADS)

Parker, D. G.; Ulrich, R. K.; Beck, J.; Tran, T. V.

2015-12-01

We have previously applied the Bayesian automatic classification system AutoClass to solar magnetogram and intensity images from the 150 Foot Solar Tower at Mount Wilson to identify classes of solar surface features associated with variations in total solar irradiance (TSI) and, using those identifications, modeled TSI time series with improved accuracy (r > 0.96). (Ulrich, et al, 2010) AutoClass identifies classes by a two-step process in which it: (1) finds, without human supervision, a set of class definitions based on specified attributes of a sample of the image data pixels, such as magnetic field and intensity in the case of MWO images, and (2) applies the class definitions thus found to new data sets to identify automatically in them the classes found in the sample set. HMI high resolution images capture four observables-magnetic field, continuum intensity, line depth and line width-in contrast to MWO's two observables-magnetic field and intensity. In this study, we apply AutoClass to the HMI observables for images from June, 2010 to December, 2014 to identify solar surface feature classes. We use contemporaneous TSI measurements to determine whether and how variations in the HMI classes are related to TSI variations and compare the characteristic statistics of the HMI classes to those found from MWO images. We also attempt to derive scale factors between the HMI and MWO magnetic and intensity observables.The ability to categorize automatically surface features in the HMI images holds out the promise of consistent, relatively quick and manageable analysis of the large quantity of data available in these images. Given that the classes found in MWO images using AutoClass have been found to improve modeling of TSI, application of AutoClass to the more complex HMI images should enhance understanding of the physical processes at work in solar surface features and their implications for the solar-terrestrial environment.Ulrich, R.K., Parker, D, Bertello, L. and

Inter-observer variation in identifying mammals from their tracks at enclosed track plate stations

Treesearch

William J. Zielinski; Fredrick V. Schlexer

2009-01-01

Enclosed track plate stations are a common method to detect mammalian carnivores. Studies rely on these data to make inferences about geographic range, population status and detectability. Despite their popularity, there has been no effort to document inter-observer variation in identifying the species that leave their tracks. Four previous field crew leaders...

Observations of hysteresis in solar cycle variations among seven solar activity indicators

NASA Technical Reports Server (NTRS)

Bachmann, Kurt T.; White, Oran R.

1994-01-01

We show that smoothed time series of 7 indices of solar activity exhibit significant solar cycle dependent differences in their relative variations during the past 20 years. In some cases these observed hysteresis patterns start to repeat over more than one solar cycle, giving evidence that this is a normal feature of solar variability. Among the indices we study, we find that the hysteresis effects are approximately simple phase shifts, and we quantify these phase shifts in terms of lag times behind the leading index, the International Sunspot Number. Our measured lag times range from less than one month to greater than four months and can be much larger than lag times estimated from short-term variations of these same activity indices during the emergence and decay of major active regions. We argue that hysteresis represents a real delay in the onset and decline of solar activity and is an important clue in the search for physical processes responsible for changing solar emission at various wavelengths.

Analysis and interpretation of lidar observations of the stratospheric aerosol

NASA Technical Reports Server (NTRS)

Hamill, P.; Swissler, T. J.; Osborn, M.; Mccormick, M. P.

1980-01-01

Data obtained with a 48 in. telescope lidar system are compared with results obtained using a one-dimensional stratospheric aerosol model to analyze various microphysical processes influencing the formation of this aerosol. Special attention is given to the following problems: (1) how lidar data can help determine the composition of the aerosol particles and (2) how the layer corresponds to temperature profile variations. The lidar record during the period 1974 to 1979 shows a considerable decrease of the peak value of the backscatter ratio. Seasonal variations in the aerosol layer and a gradual decrease in stratospheric loading are observed. The aerosol model simulates a background stratospheric aerosol layer, and it predicts stratospheric aerosol concentrations and compositions. Numerical experiments are carried out by using the model and by comparing the theoretical results with the experimentally obtained lidar record. Comparisons show that the backscatter profile is consistent with the composition when the particles are sulfuric acid and water; it is not consistent with an ammonium sulfate composition. It is shown that the backscatter ratio is not sensitive to the composition or stratospheric loading of condensation nuclei such as meteoritic debris.

Possible causes of variation in acrylamide concentration in French fries prepared in food service establishments: an observational study.

PubMed

Sanny, M; Jinap, S; Bakker, E J; van Boekel, M A J S; Luning, P A

2012-05-01

Acrylamide is a probable human carcinogen, and its presence in a range of fried and oven-cooked foods has raised considerable health concern world-wide. Dietary intake studies observed significant variations in acrylamide concentrations, which complicate risk assessment and the establishment of effective control measures. The objective of this study was to obtain an insight into the actual variation in acrylamide concentrations in French fries prepared under typical conditions in a food service establishment (FSE). Besides acrylamide, frying time, frying temperature, and reducing sugars were measured and the actual practices at receiving, thawing and frying during French fries preparation were observed and recorded. The variation in the actual frying temperature contributed most to the variation in acrylamide concentrations, followed by the variation in actual frying time; no obvious effect of reducing sugars was found. The lack of standardised control of frying temperature and frying time (due to inadequate frying equipment) and the variable practices of food handlers seem to contribute most to the large variation and high acrylamide concentrations in French fries prepared in a restaurant type of FSE as compared to chain fast-food services, and institutional caterers. The obtained insights in this study can be used to develop dedicated control measures in FSE, which may contribute to a sustainable reduction in the acrylamide intake. Copyright © 2011 Elsevier Ltd. All rights reserved.

Analysis of Fracture Mechanism for Al-Mg/SiCp Composite Materials

NASA Astrophysics Data System (ADS)

Maleque, M. A.; Adebisi, A. A.; Izzati, N.

2017-03-01

The present study aims to examine the fracture mechnism of silicon carbide particle (SiCp) reinforced aluminium matrix composite (AMC) material with 1 wt% addition of magnesium is fabricated using the stir casting process. The aluminium composite (Al-Mg/SiCp) is investigated for fatigue life and impact strength considering reinforcement weight fraction and influence of temperature on fracture toughness. The fabricated composite was tested using fatigue testing machine and charpy impact tester. Fractographic observations were evaluated with the scanning electron microscopy (SEM) on the fracture surface. It was found that increasing the SiCp weight fraction increased the fatigue life of the composite. Moreover, the 20 wt% SiCp Al-Mg composite attained the highest number of cycle and fatigue life compared to other variations. The mechanism responsible for the phenomena includes load transfer from the Al matrix alloy phase to the high strength and stiffness of the incorporated SiCp. The temperature variation influenced the impact strength of the composite and improved fracture toughness is achieved at 150 °C. It can be concluded from this study that reinforcement weight fraction and temperature affects the fracture behavior of the composites.

Historical variations in the stable isotope composition of mercury in Arctic lake sediments.

PubMed

Jackson, Togwell A; Muir, Derek C G; Vincent, Warwick F

2004-05-15

The stable isotope composition of mercury (Hg) in a dated core from the anoxic zone of a saline, meromictic Arctic lake was found to vary as a complex function of the age and chemical composition of the sediment. Throughout the stratigraphic sequence, which spans the years 1899-1997, the ratios 198Hg/202Hg, 199Hg/202Hg, 200Hg/202Hg, 201Hg/202Hg, and 204Hg/202Hg expressed as delta-values (per mil deviations relative to a standard) reveal enrichment in 198Hg, 199Hg, 200Hg, and 201Hg, with depletion in 204Hg, the degree of enrichment varying inversely with atomic mass. A plot of delta198Hg, delta199Hg, delta200Hg, and delta201Hg against depth gave parallel profiles characterized by large, regular undulations superimposed on an overall trend toward increase with depth (i.e. age), and the delta204Hg profile is a mirror image of them. The delta198Hg, delta199Hg, delta200Hg, and delta201Hg values of the oldest (1899-1929) strata vary inversely with NH2OH.HCl/HNO3-extractable manganese concentration, but those of the youngest (1963-1997) strata give a positive correlation; intermediate (1936-1956) strata show no correlation and negligible variation in delta-values, possibly signifying a transition phase in which the two opposite trends offset each other. The delta-values show similar but weaker relationships with organic carbon. The results strongly suggest fractionation of Hg isotopes by microbial activities linked to oxidation-reduction reactions in the lake, although effects of isotopic signatures indicative of the sources of the Hg have not been ruled out. The radical change in the nature of the relationship between 6-values and sediment chemistry over time may reflect environmental and biotic changes that altered the isotope-fractionating processes. These findings imply that variations in the isotopic makeup of Hg, together with related physical, chemical, and biological data, could yield important new information about the biogeochemical cycle of Hg.

Modeling the Structure of Composite Supernova Remnants

NASA Astrophysics Data System (ADS)

Slane, Patrick

2015-09-01

The dynamical structure of a composite SNR, along with its broadband emission, provides crucial constraints on the ejecta mass and explosion energy, the properties of the pulsar that powers the associated wind nebula, and the ultimate fate of the particles that it injects. Of particular importance is the effect of asymmetries introduced through spatial variations in the ambient medium density and by rapid motion of the pulsar. Here we propose hydrodynamical and semi-analytical modeling of G21.5-0.9 and G292.0+1.8, SNRs for which deep Chandra observations have provided key input parameters for these models. We will derive ambient conditions and pulsar properties that lead to the observed morphology, broadband emission, and shock conditions in these important composite systems.

Interstellar extinction curve variations towards the inner Milky Way: a challenge to observational cosmology

NASA Astrophysics Data System (ADS)

Nataf, David M.; Gonzalez, Oscar A.; Casagrande, Luca; Zasowski, Gail; Wegg, Christopher; Wolf, Christian; Kunder, Andrea; Alonso-Garcia, Javier; Minniti, Dante; Rejkuba, Marina; Saito, Roberto K.; Valenti, Elena; Zoccali, Manuela; Poleski, Radosław; Pietrzyński, Grzegorz; Skowron, Jan; Soszyński, Igor; Szymański, Michał K.; Udalski, Andrzej; Ulaczyk, Krzysztof; Wyrzykowski, Łukasz

2016-03-01

We investigate interstellar extinction curve variations towards ˜4 deg2 of the inner Milky Way in VIJKs photometry from the OGLE-III (third phase of the Optical Gravitational Lensing Experiment) and VVV (VISTA Variables in the Via Lactea) surveys, with supporting evidence from diffuse interstellar bands and F435W, F625W photometry. We obtain independent measurements towards ˜2000 sightlines of AI, E(V - I), E(I - J) and E(J - Ks), with median precision and accuracy of 2 per cent. We find that the variations in the extinction ratios AI/E(V - I), E(I - J)/E(V - I) and E(J - Ks)/E(V - I) are large (exceeding 20 per cent), significant and positively correlated, as expected. However, both the mean values and the trends in these extinction ratios are drastically shifted from the predictions of Cardelli and Fitzpatrick, regardless of how RV is varied. Furthermore, we demonstrate that variations in the shape of the extinction curve have at least two degrees of freedom, and not one (e.g. RV), which we confirm with a principal component analysis. We derive a median value of = 13.44, which is ˜60 per cent higher than the `standard' value. We show that the Wesenheit magnitude WI = I - 1.61(I - J) is relatively impervious to extinction curve variations. Given that these extinction curves are linchpins of observational cosmology, and that it is generally assumed that RV variations correctly capture variations in the extinction curve, we argue that systematic errors in the distance ladder from studies of Type Ia supernovae and Cepheids may have been underestimated. Moreover, the reddening maps from the Planck experiment are shown to systematically overestimate dust extinction by ˜100 per cent and lack sensitivity to extinction curve variations.

Seasonal Variations of Atmospheric CO2 over Fire Affected Regions Based on GOSAT Observations

NASA Astrophysics Data System (ADS)

Shi, Y.; Matsunaga, T.

2016-12-01

Abstract: The carbon dioxide (CO2) emissions released from biomass burning significantly affect the temporal variations of atmospheric CO2 concentrations. Based on a long-term (July 2009-June 2015) retrieved datasets by the Greenhouse Gases Observing Satellite (GOSAT), the seasonal cycle and interannual variations of column-averaged volume mixing ratios of atmospheric carbon dioxide (XCO2) in four fire affected continental regions were investigated. The results showed Northern Africa had the largest seasonal variations after removing its regional long-term trend of XCO2 with peak-to-peak amplitude of 6.2 ppm within the year, higher than central South America (2.4 ppm), Southern Africa (3.8 ppm) and Australia (1.7 ppm). The detrended regional XCO2 was found to be positively correlated with the fire CO2 emissions during fire activity period and negatively correlated with vegetation photosynthesis activity with different seasonal variabilities. Northern Africa recorded the largest change of seasonal variations of detrended XCO2 with a total of 12.8 ppm during fire seasons, higher than central South America, Southern Africa and Australia with 5.4 ppm, 6.7 ppm and 2.2 ppm, respectively. During fire episode, the positive detrended XCO2 was noticed during June-November in central South America, December-June in Northern Africa, May-November in Southern Africa. The Pearson correlation coefficients between the variations of detrended XCO2 and fire CO2 emissions from GFED4 (Global Fire Emissions Database v4) achieved best correlations in Southern Africa (R=0.77, p<0.05). Meanwhile, Southern Africa also experienced a significant negative relationship between the variations of detrended XCO2 and vegetation activity (R=-0.84, p<0.05). This study revealed that fire CO2 emissions and vegetation activity contributed greatly to the seasonal variations of GOSAT XCO2 dataset.

Spatio-temporal Variations of Nitrogen Dioxide over Western China from Satellite Observations during 2005-2013

NASA Astrophysics Data System (ADS)

Cui, Y.; Lin, J.; Huang, B.; Song, C.

2015-12-01

Western China has experienced rapid urbanization and industrialization since the implementation of National Western Development Strategy by Chinese Government. Most resource-intensive industries and high-pollution factories had been moved from the east coast to Western China after 2000. In this research, the spatial and temporal variations of tropospheric NO2 concentration in 2005 - 2013 is analyzed based on the satellite observations by Ozone Measurement Instrument (OMI). The annual trends and seasonality of tropospheric NO2 over Western China are calculated. The results show that large increases are observed in urban areas and the polluted regions are expanding. Additionally, the seasonal patterns of some regions over Western China are changing significantly and more clean areas tend to changing from the characteristics of natural emissions to those of anthropogenic emissions. The spatial and temporal variations of NO2 concentrations are well responded to the rapid urbanization and industrialization over Western China.

Variation of Equatorial F-region Vertical Neutral Wind and Neutral Temperature during Geomagnetic Storms: Brazil FPI Observations

NASA Astrophysics Data System (ADS)

Sheng, C.; De La Garza, J. L.; Deng, Y.; Makela, J. J.; Fisher, D. J.; Meriwether, J. W.; Mesquita, R.

2015-12-01

An accurate description of vertical neutral winds in the thermosphere is essential to understand how the upper atmosphere responds to the geomagnetic storms. However, vertical wind measurements are difficult to obtain and there are still limited data. Recent observation deployments now permit substantial progress on this issue. In this paper, neutral vertical wind data from Brazil FPI observations at around 240 km altitude during 2009 to 2015 are used for the study of the equatorial vertical wind and neutral temperature variation during geomagnetic activity times. First, the observations during several particular storm periods will be analyzed. Secondly, Epoch analysis will be used to bin all the observed events together to investigate the climatological features of vertical wind and temperature during storms. The results will give us an unprecedented view of the nighttime vertical wind and neutral temperature variations at low latitudes, which is critical to specify the dynamics of the upper atmosphere.

Effects of the observed J2 variations on the Earth's precession and nutation

NASA Astrophysics Data System (ADS)

Ferrándiz, José M.; Baenas, Tomás; Belda, Santiago

2016-04-01

The Earth's oblateness parameter J2 is closely related to the dynamical ellipticity H, which factorizes the main components of the precession and the different nutation terms. In most theoretical approaches to the Earth's rotation, with IAU2000 nutation theory among them, H is assumed to be constant. The precession model IAU2006 supposes H to have a conventional linear variation, based on the J2 time series derived mainly from satellite laser ranging (SLR) data for decades, which gives rise to an additional quadratic term of the precession in longitude and some corrections of the nutation terms. The time evolution of J2 is, however, too complex to be well approximated by a simple linear model. The effect of more general models including periodic terms and closer to the observed time series, although still unable to reproduce a significant part of the signal, has been seldom investigated. In this work we address the problem of deriving the effect of the observed J2 variations without resorting to such simplified models. The Hamiltonian approach to the Earth rotation is extended to allow the McCullagh's term of the potential to depend on a time-varying oblateness. An analytical solution is derived by means of a suitable perturbation method in the case of the time series provided by the Center for Space Research (CSR) of the University of Texas, which results in non-negligible contributions to the precession-nutation angles. The presentation focuses on the main effects on the longitude of the equator; a noticeable non-linear trend is superimposed to the linear main precession term, along with some periodic and decadal variations.

Intraspecific Variation in Female Sex Pheromone of the Codling Moth Cydia pomonella

PubMed Central

Duménil, Claire; Judd, Gary J. R.; Bosch, Dolors; Baldessari, Mario; Gemeno, César; Groot, Astrid T.

2014-01-01

The codling moth, Cydia pomonella L. (Lepidoptera, Tortricidae), is a major pest of apple, pear and walnut orchards worldwide. This pest is often controlled using the biologically friendly control method known as pheromone-based mating disruption. Mating disruption likely exerts selection on the sexual communication system of codling moth, as male and female moths will persist in their attempt to meet and mate. Surprisingly little is known on the intraspecific variation of sexual communication in this species. We started an investigation to determine the level of individual variation in the female sex pheromone composition of this moth and whether variation among different populations might be correlated with use of mating disruption against those populations. By extracting pheromone glands of individual females from a laboratory population in Canada and from populations from apple orchards in Spain and Italy, we found significant between- and within-population variation. Comparing females that had been exposed to mating disruption, or not, revealed a significant difference in sex pheromone composition for two of the minor components. Overall, the intraspecific variation observed shows the potential for a shift in female sexual signal when selection pressure is high, as is the case with continuous use of mating disruption. PMID:26462935

Intraspecific Variation in Female Sex Pheromone of the Codling Moth Cydia pomonella.

PubMed

Duménil, Claire; Judd, Gary J R; Bosch, Dolors; Baldessari, Mario; Gemeno, César; Groot, Astrid T

2014-09-26

The codling moth, Cydia pomonella L. (Lepidoptera, Tortricidae), is a major pest of apple, pear and walnut orchards worldwide. This pest is often controlled using the biologically friendly control method known as pheromone-based mating disruption. Mating disruption likely exerts selection on the sexual communication system of codling moth, as male and female moths will persist in their attempt to meet and mate. Surprisingly little is known on the intraspecific variation of sexual communication in this species. We started an investigation to determine the level of individual variation in the female sex pheromone composition of this moth and whether variation among different populations might be correlated with use of mating disruption against those populations. By extracting pheromone glands of individual females from a laboratory population in Canada and from populations from apple orchards in Spain and Italy, we found significant between- and within-population variation. Comparing females that had been exposed to mating disruption, or not, revealed a significant difference in sex pheromone composition for two of the minor components. Overall, the intraspecific variation observed shows the potential for a shift in female sexual signal when selection pressure is high, as is the case with continuous use of mating disruption.

Diet composition as a source of variation in experimental animal models of cancer cachexia

PubMed Central

Giles, Kaitlin; Guan, Chen; Jagoe, Thomas R.

2015-01-01

Abstract Background A variety of experimental animal models are used extensively to study mechanisms underlying cancer cachexia, and to identify potential treatments. The important potential confounding effect of dietary composition and intake used in many preclinical studies of cancer cachexia is frequently overlooked. Dietary designs applied in experimental studies should maximize the applicability to human cancer cachexia, meeting the essential requirements of the species used in the study, matched between treatment and control groups as well as also being generally similar to human consumption. Methods A literature review of scientific studies using animal models of cancer and cancer cachexia with dietary interventions was performed. Studies that investigated interventions using lipid sources were selected as the focus of discussion. Results The search revealed a number of nutrient intervention studies (n = 44), with the majority including n‐3 fatty acids (n = 16), mainly eicosapentaenoic acid and/or docosahexaenoic acid. A review of the literature revealed that the majority of studies do not provide information about dietary design; food intake or pair‐feeding is rarely reported. Further, there is a lack of standardization in dietary design, content, source, and overall composition in animal models of cancer cachexia. A model is proposed with the intent of guiding dietary design in preclinical studies to enable comparisons of dietary treatments within the same study, translation across different study designs, as well as application to human nutrient intakes. Conclusion The potential for experimental endpoints to be affected by variations in food intake, macronutrient content, and diet composition is likely. Diet content and composition should be reported, and food intake assessed. Minimum standards for diet definition in cachexia studies would improve reproducibility of pre‐clinical studies and aid the interpretation and translation of results

Diet composition as a source of variation in experimental animal models of cancer cachexia.

PubMed

Giles, Kaitlin; Guan, Chen; Jagoe, Thomas R; Mazurak, Vera

2016-05-01

A variety of experimental animal models are used extensively to study mechanisms underlying cancer cachexia, and to identify potential treatments. The important potential confounding effect of dietary composition and intake used in many preclinical studies of cancer cachexia is frequently overlooked. Dietary designs applied in experimental studies should maximize the applicability to human cancer cachexia, meeting the essential requirements of the species used in the study, matched between treatment and control groups as well as also being generally similar to human consumption. A literature review of scientific studies using animal models of cancer and cancer cachexia with dietary interventions was performed. Studies that investigated interventions using lipid sources were selected as the focus of discussion. The search revealed a number of nutrient intervention studies (n = 44), with the majority including n-3 fatty acids (n = 16), mainly eicosapentaenoic acid and/or docosahexaenoic acid. A review of the literature revealed that the majority of studies do not provide information about dietary design; food intake or pair-feeding is rarely reported. Further, there is a lack of standardization in dietary design, content, source, and overall composition in animal models of cancer cachexia. A model is proposed with the intent of guiding dietary design in preclinical studies to enable comparisons of dietary treatments within the same study, translation across different study designs, as well as application to human nutrient intakes. The potential for experimental endpoints to be affected by variations in food intake, macronutrient content, and diet composition is likely. Diet content and composition should be reported, and food intake assessed. Minimum standards for diet definition in cachexia studies would improve reproducibility of pre-clinical studies and aid the interpretation and translation of results to humans with cancer.

Environmental variation between habitats and uptake of heavy metals by Urtica dioica.

PubMed

Otte, M L; Wijte, A H

1993-12-01

The observation from previous surveys, that Urtica dioica plants that had grown in metal contaminated soil in the floodplains of the former Rhine estuary in different habitats, but at comparable total soil metal concentrations, showed significant differences in tissue metal concentrations, led to the hypothesis that variation in other environmental characteristics than soil composition and chemical speciation of metals between habitats is also important in determining uptake and translocation of metals in plants. A field survey indicated that differences in root Cd, Cu and Zn concentrations might partly be explained by variation in speciation of metals in different habitats. However, shoot concentrations showed a different pattern that did not relate to variation in soil metal concentrations. In a habitat experiment Urtica dioica plants were grown in artificially contaminated soil in pots that were placed in the four habitats (grassland, pure reed, mixed reed, osier bed) that were also included in the field survey. After seven weeks the plants showed significant differences in Cu and Zn concentrations in roots and aboveground plant parts and in distribution of the metals in the plants between habitats. It was concluded that variation between habitats in environmental characteristics other than soil composition can explain as much variation in plants as can variation in soil metal concentrations and/or speciation. The implications for assessment of soil metal contamination and uptake by plants are discussed.

Variable electrical properties in composites: Application to vanadium dioxide pigments in a polyethylene host

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alfred-Duplan, C.; Musso, J.; Gavarri, J.R.

1994-05-01

Composite pellets were prepared from low-density polyethylene (LDPE) and vanadium dioxide powders. The VO[sub 2] pigments are used for their insulating-to-metallic transition at 341 K in order to obtain electrically variable composite materials. The volume fractions of VO[sub 2] powders vary from [phi] = 0 to [phi] = 0.55. The composite samples are characterized by X-ray diffraction and scanning electron microscopy. Complex impedance analysis in the frequency range 10[sup [minus]1] to 10[sup 6]. Hz is carried out at room temperature and at T = 363 K, to observe the insulator-metal transition of VO[sub 2] pigments dispersed in the polymer host.more » The variation of the complex impedance modulus [vert bar]Z[vert bar] with frequency and with VO[sub 2] volume fraction ([phi]) is discussed. A specific (R, C) impedance model permits interpretation of the experimental results in terms of percolation; the observed variations can be accounted for.« less

Quantification of processing artifacts in textile composites

NASA Technical Reports Server (NTRS)

Pastore, Christopher M.

1993-01-01

One of the greatest difficulties in developing detailed models of the mechanical response of textile reinforced composites is an accurate model of the reinforcing elements. In the case of elastic property prediction, the variation of fiber position may not have a critical role in performance. However, when considering highly localized stress events, such as those associated with cracks and holes, the exact position of the reinforcement probably dominates the failure mode. Models were developed for idealized reinforcements which provide an insight into the local behavior. However, even casual observations of micrographical images reveals that the actual material deviates strongly from the idealized models. Some of the deviations and causes are presented for triaxially braided and three dimensionally woven textile composites. The necessary modeling steps to accommodate these variations are presented with some examples. Some of the ramifications of not accounting for these discrepencies are also addressed.

Understanding the effect of compositions on electronegativity, atomic radius and thermal stability of Mg-Ni-Y amorphous alloy

NASA Astrophysics Data System (ADS)

Deshmukh, A. A.; Kuthe, S. A.; Palikundwar, U. A.

2018-05-01

In the present paper, the consequences of variation in compositions on the electronegativity (ΔX), atomic radius difference (δ) and the thermal stability (ΔTx) of Mg-Ni-Y bulk metallic glasses (BMGs) are evaluated. In order to understand the effect of variation in compositions on ΔX, δ and ΔTx, regression analysis is performed on the experimentally available data. A linear correlation between both δ and ΔX with regression coefficient 0.93 is observed. Further, compositional variation is performed with δ and then it is correlated to the ΔTx by deriving subsequent equations. It is observed that concentration of Mg, Ni and Y are directly proportional to the δ with regression coefficients 0.93, 0.93 and 0.50 respectively. The positive slope of Ni and Y stated that ΔTx will increase if it has more contribution from both Ni and Y. On the other hand negative slope stated that composition of Mg should be selected in such a way that it will have more stability with Ni and Y. The results obtained from mathematical calculations are also tested by regression analysis of ΔTx with the compositions of individual elements in the alloy. These results conclude that there is a strong dependence of ΔTx of the alloy on the compositions of the constituting elements in the alloy.

Variation in essential oil composition within individual leaves of sweet basil (Ocimum basilicum L.) is more affected by leaf position than by leaf age.

PubMed

Fischer, Ravit; Nitzan, Nadav; Chaimovitsh, David; Rubin, Baruch; Dudai, Nativ

2011-05-11

The aroma in sweet basil is a factor affecting the commercial value of the crop. In previous studies leaf age was considered to be a factor that influences the composition of essential oil (EO). In this study it was hypothesized that a single observation of the EO content in leaves from different positions on the main stem (young vs old) could predict the developmental changes in the plant during its life cycle. Plants harvested at week 16 demonstrated an exponential increase (R(2) = 0.92) in EO concentration in leaves on the main stem and lateral shoots, indicating higher EO concentrations in younger than in older leaves. Eugenol and methyleugenol predominated (28-77%) in the extract. Eugenol levels were higher in younger leaves (∼53%), and methyl-eugenol levels predominated in older leaves (∼68%). Linalool was lower in mature leaves than in younger leaves. This suggested that eugenol converted into methyleugenol and linalool decreased as leaf mature. However, in weekly monitored plants, the levels of these compounds in the EO had limited variation in the maturing leaf regardless of its position on the stem. This proposed that the EO composition in an individual leaf is mostly affected by the leaf position on the stem and not by its maturation process. Because leaf position is related to plant development, it is probable that the plant's physiological age at the time of leaf formation from the primordial tissue is the factor affecting the EO composition. It was concluded that interpretation of scientific observations should be carried out with caution and that hypotheses should be tested utilizing multifaceted approaches.

Microstructure, mechanical and fretting wear properties of TiC-stainless steel composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Akhtar, F.; Department of Metallurgical and Materials Engineering, University of Engineering and Technology, Lahore; Guo, S.J.

2008-01-15

This study deals with the processing, microstructure, and wear behavior of TiC-reinforced stainless steel matrix composites, containing 50 to 70 wt.% TiC. Powder technology was used to successfully fabricate the composites. The microstructure of the composite was characterized by scanning electron microscopy. The microstructural study revealed that the TiC particles were distributed uniformly in the steel matrix phase. Interface debonding and microcracks were not observed in the composite. The composite hardness increased with TiC content. The fretting wear resistance of the composites was studied against high speed steel. The wear mechanisms are discussed by means of microscopical observations on themore » worn surfaces. The wear was severe at higher wear loads and lower TiC content. Microplowing of the stainless steel matrix was found to be the dominant wear mechanism. Heavy microplowing and rapid removal of material from the wear surface was observed at high wear load. The variation of wear loss with volume fraction and mean free path of the binder phase is also reported.« less

Magnetic Ripples Observed by Low-altitude Satellites and their Relation to Micro-barometric and Ground Magnetic Variations

NASA Astrophysics Data System (ADS)

Iyemori, T.; Aoyama, T.; Nakanishi, K.; Odagi, Y.; Sanoo, Y.; Yokoyama, Y.; Yamada, A.

2017-12-01

The `magnetic ripples' are small scale magnetic fluctuations observed in upper ionosphere by low altitude satellites such as CHAMP or Swarm, and they are spatial structure of field-aligned currents along satellite orbit. They are observed almost always in mid- and low-latitudes. From their geographical and seasonal characteristics, they are supposed to be caused by the atmospheric waves which propagates from lower atmosphere to the ionosphere. Although the global distribution and its local time or seasonal variation of the amplitude of magnetic ripples, or the correlation with meteorological phenomena such as typhoons strongly suggest the cumulus convection as the main origin, we need to clarify which mode of atmospheric waves, i.e., acoustic wave or internal gravity wave, mainly contributes to the magnetic ripples and what meteorological condition correspond them. For those purposes, we analyze ground based magnetic and micro-barometric variations. We try to make quantitative estimation of the contribution from both acoustic and internal mode of gravity waves, acoustic resonance, etc. by calculating PSD (power spectral density) of pressure and ground magnetic variations. In this paper, we present their basic characteristics and discuss the relation with magnetic ripples. [Acknowledgments]: The ground observations have been supported by many people including students at our graduate school and by the collaboration with other institutions.

Depth-dependent variations of sedimentary dissolved organic matter composition in a eutrophic lake: Implications for lake restoration.

PubMed

Xu, Huacheng; Guo, Laodong; Jiang, Helong

2016-02-01

Dissolved organic matter (DOM) plays a significant role in regulating nutrients and carbon cycling and the reactivity of trace metals and other contaminants in the environment. However, the environmental/ecological role of sedimentary DOM is highly dependent on organic composition. In this study, fluorescence excitation emission matrix-parallel factor (EEM-PARAFAC) analysis, two dimensional correlation spectroscopy (2D-COS), and ultrahigh resolution electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) were applied to investigate the depth-dependent variations of sediment-leached DOM components in a eutrophic lake. Results of EEM-PARAFAC and 2D-COS showed that fluorescent humic-like component was preferentially degraded microbially over fulvic-like component at greater sediment depths, and the relative abundance of non-fluorescent components decreased with increasing depth, leaving the removal rate of carbohydrates > lignins. The predominant sedimentary DOM components derived from FT-ICR-MS were lipids (>50%), followed by lignins (∼15%) and proteins (∼15%). The relative abundance of carbohydrates, lignins, and condensed aromatics decreased significantly at greater depths, whereas that of lipids increased in general with depth. There existed a significant negative correlation between the short-range ordered (SRO) minerals and the total dissolved organic carbon concentration or the relative contents of lignins and condensed aromatics (p < 0.05), suggesting that SRO mineral sorption plays a significant role in controlling the composition heterogeneity and releasing of DOM in lake sediments. Higher metal binding potential observed for DOM at deeper sediment depth (e.g., 25-30 cm) supported the ecological safety of sediment dredging technique from the viewpoint of heavy metal de-toxicity. Copyright © 2015 Elsevier Ltd. All rights reserved.

Spatial and temporal variation in the stable isotope composition (δ18O and δ2H) of rain across the tropical island of Sri Lanka.

PubMed

Edirisinghe, E A N V; Pitawala, H M T G A; Dharmagunawardhane, H A; Wijayawardane, R L

2017-12-01

Seasonal and spatial variation in δ 18 O and δ 2 H in rainwater was determined in three selected transects across Sri Lanka, the tropical island in the Indian Ocean. Local meteoric water lines (LMWLs) for three distinguished climatic zones; wet, dry and intermediate were constructed. LMWLs show slight variations in their gradients and respective d-excess values, depending on the air moisture origin, circulation and environmental conditions of each climatic zone. The elevation effect and amount effect could be identified but the continental effect is not significantly seen in the isotope composition of rain in the concerned areas. The results reasonably revealed that the distinct rainfall regimes; two monsoonal rains and two convectional (inter-monsoon) rains have characteristic isotopic signatures. Also the impact of (i) terrestrial and oceanic moisture sources, (ii) depression and cyclonic conditions of the Bay of Bengal, and (iii) topography of the country on the variation of the isotopic composition of rain in Sri Lanka could be satisfactorily identified.

Effect of Trader Composition on Stock Market

NASA Astrophysics Data System (ADS)

Wang, Mo-Gei; Wang, Xing-Yuan; Liu, Zhen-Zhen

2011-05-01

In this study, we build a double auction market model, which contains two types of agent traders, i.e., the noise traders and fundamentalists, to investigate the effect of the trader composition on the stock market. It is found that, the non-trivial Hurst exponent and the fat-tailed distribution of transaction prices can be observed at any ratio of the noise traders. Analyses on the price variation properties, including the Hurst exponent and the price variation region, show that these properties are stable when the ratio is moderate. However, the non-price variation properties, including the trading volume and the profitability of the two kinds of agents, do not keep stable untrivially in any interval of the ratio of noise traders.

Natural habitats matter: Determinants of spatial pattern in the composition of animal assemblages of the Czech Republic

NASA Astrophysics Data System (ADS)

Divíšek, Jan; Zelený, David; Culek, Martin; Št'astný, Karel

2014-08-01

Studies that explore species-environment relationships at a broad scale are usually limited by the availability of sufficient habitat description, which is often too coarse to differentiate natural habitat patches. Therefore, it is not well understood how the distribution of natural habitats affects broad-scale patterns in the distribution of animal species. In this study, we evaluate the role of field-mapped natural habitats, land-cover types derived from remote sensing and climate on the composition of assemblages of five distinct animal groups, namely non-volant mammals, birds, reptiles, amphibians and butterflies native to the Czech Republic. First, we used variation partitioning based on redundancy analysis to evaluate the extent to which the environmental variables and their spatial structure might underlie the observed spatial patterns in the composition of animal assemblages. Second, we partitioned variations explained by climate, natural habitats and land-cover to compare their relative importance. Finally, we tested the independent effects of each variable in order to evaluate the significance of their contributions to the environmental model. Our results showed that spatial patterns in the composition of assemblages of almost all the considered animal groups may be ascribed mostly to variations in the environment. Although the shared effects of climatic variables, natural habitats and land-cover types explained the largest proportion of variation in each animal group, the variation explained purely by natural habitats was always higher than the variation explained purely by climate or land-cover. We conclude that most spatial variation in the composition of assemblages of almost all animal groups probably arises from biological processes operating within a spatially structured environment and suggest that natural habitats are important to explain observed patterns because they often perform better than habitat descriptions based on remote sensing. This

Spatial Variations of Poloidal and Toroidal Mode Field Line Resonances Observed by MMS

NASA Astrophysics Data System (ADS)

Le, G.; Chi, P. J.; Strangeway, R. J.; Russell, C. T.; Slavin, J. A.; Anderson, B. J.; Kepko, L.; Nakamura, R.; Plaschke, F.; Torbert, R. B.

2017-12-01

Field line resonances (FLRs) are magnetosphere's responses to solar wind forcing and internal instabilities generated by solar wind-magnetospheric interactions. They are standing waves along the Earth's magnetic field lines oscillating in either poloidal or toroidal modes. The two types of waves have their unique frequency characteristics. The eigenfrequency of FLRs is determined by the length of the field line and the plasma density, and thus gradually changes with L. For toroidal mode oscillations with magnetic field perturbations in the azimuthal direction, ideal MHD predicts that each field line oscillates independently with its own eigenfrequency. For poloidal mode waves with field lines oscillating radially, their frequency cannot change with L easily as L shells need to oscillate in sync to avoid efficient damping due to phase mixing. Observations, mainly during quiet times, indeed show that poloidal mode waves often exhibit nearly constant frequency across L shells. Our recent observations, on the other hand, reveal a clear L-dependent frequency trend for a long lasting storm-time poloidal wave event, indicating the wave can maintain its power with changing frequencies for an extended period [Le et al., 2017]. The spatial variation of the frequency shows discrete spatial structures. The frequency remains constant within each discrete structure that spans about 1 REalong L, and changes discretely. We present a follow-up study to investigate spatial variations of wave frequencies using the Wigner-Ville distribution. We examine both poloidal and toroidal waves under different geomagnetic conditions using multipoint observations from MMS, and compare their frequency and occurrence characteristics for insights into their generation mechanisms. Reference: Le, G., et al. (2017), Global observations of magnetospheric high-m poloidal waves during the 22 June 2015 magnetic storm, Geophys. Res. Lett., 44, 3456-3464, doi:10.1002/2017GL073048.

Chemical variations within and between the clasts, and the matrix of the Abee enstatite chondrite suggest an impact-based differentiation mechanism

NASA Astrophysics Data System (ADS)

Higgins, Michael D.; Martin, Pierre-Etienne M. C.

2018-01-01

Abee is an enstatite chondrite breccia dominantly composed of kamacite, enstatite, silica, plagioclase, troilite and niningerite. Clasts are up to 220 mm long and vary in shape from angular to rounded. Some clasts are zoned with kamacite-enriched rims that follow the edge of the clast. Spatial compositional variations were examined in a small block to find out more about the petrological processes that produced this rock, particularly the relationship between the clasts, the matrix and the cores/rims of the zoned clasts. Compositional maps produced using a focussed-beam XRF were segmented into clasts and matrix, and rims and cores where possible. Compositions of most clasts, matrix and rim/cores define a simple, linear trend on simple variation diagrams. If it is assumed that all components were derived from an original homogeneous composition then the variation can be explained either by addition of kamacite or by loss of all other phases. Within this overall compositional variation the kamacite content generally increases as follows: matrix < large homogeneous clasts ≈ zoned clast cores < small homogeneous clasts ≈ zoned clast rims. Production of diversity by addition of kamacite to clasts and rim seems to require a complex history as the source cannot have been the current matrix. It is also difficult to produce the observed chemical variations and zoning by partial melting. However, differentiation by removal of all non-metallic phases may result from repeated impacts: Shock waves would deform kamacite whilst fracturing all other phases. The broken grains would then migrate towards the surface of the clasts where they would spall off into the matrix. This process would also lead to the observed rounding of some clasts. We propose that this shock-differentiation process be called 'smithing', as it resembles the ancient process of iron refining.

Diurnal variations of BrONO2 observed by MIPAS-B at midlatitudes and in the Arctic

NASA Astrophysics Data System (ADS)

Wetzel, Gerald; Oelhaf, Hermann; Höpfner, Michael; Friedl-Vallon, Felix; Ebersoldt, Andreas; Gulde, Thomas; Kazarski, Sebastian; Kirner, Oliver; Kleinert, Anne; Maucher, Guido; Nordmeyer, Hans; Orphal, Johannes; Ruhnke, Roland; Sinnhuber, Björn-Martin

2017-12-01

The first stratospheric measurements of the diurnal variation in the inorganic bromine (Bry) reservoir species BrONO2 around sunrise and sunset are reported. Arctic flights of the balloon-borne Michelson Interferometer for Passive Atmospheric Sounding (MIPAS-B) were carried out from Kiruna (68° N, Sweden) in January 2010 and March 2011 inside the stratospheric polar vortices where diurnal variations of BrONO2 around sunrise have been observed. High nighttime BrONO2 volume mixing ratios of up to 21 pptv (parts per trillion by volume) were detected in late winter 2011 in the absence of polar stratospheric clouds (PSCs). In contrast, the amount of measured BrONO2 was significantly lower in January 2010 due to low available NO2 amounts (for the build-up of BrONO2), the heterogeneous destruction of BrONO2 on PSC particles, and the gas-phase interaction of BrO (the source to form BrONO2) with ClO. A further balloon flight took place at midlatitudes from Timmins (49° N, Canada) in September 2014. Mean BrONO2 mixing ratios of 22 pptv were observed after sunset in the altitude region between 21 and 29 km. Measurements are compared and discussed with the results of a multi-year simulation performed with the chemistry climate model ECHAM5/MESSy Atmospheric Chemistry (EMAC). The calculated temporal variation in BrONO2 largely reproduces the balloon-borne observations. Using the nighttime simulated ratio between BrONO2 and Bry, the amount of Bry observed by MIPAS-B was estimated to be about 21-25 pptv in the lower stratosphere.

Longitudinal dependence of the seasonal variations of the topside ionospheric and plasmaspheric electron content: observations and model results

NASA Astrophysics Data System (ADS)

Zhang, Man-Lian; Liu, Libo; Ning, Baiqi; Wan, Weixing

2016-07-01

Radio signals transmitted from GPS satellite going through the ionization zone above the Earth will be refracted by the ionized components in the ionosphere and the plasmasphere, which would produce additional transfer delay and generate extra errors in satellite navigation and positioning, etc. These errors have strong relation with the total electron content (TEC) along the signal's travelling path. Therefore TEC is one of the most important parameters required by many users for different modern usage purposes. The topside ionospheric and plasmaspheric electron content makes a large contribution to TEC. In the present study, data for the year 2008 of the topside ionospheric and plasmaspheric electron content (PEC) between the height of 800-20200km above the Earth derived from the upward-looking TEC measurements of the precise orbit determination antenna on board the COSMIC low Earth orbit (LEO) satellites to the GPS signals are used to study the longitudinal dependence of the seasonal variations of PEC. A comparison study of the observed PEC with the IZMIRAN_Plas model results is also made. Our study showed that PEC shows different seasonal variations at different longitudinal sectors: for the 240°E-60°E longitudinal sector, PEC shows a strong annual variation with lowest value in the June solstice and highest value in the December solstice months; In contrast, very weak seasonal variations are observed for PEC at 60°E-240°E longitudinal sector; Comparison study showed that this longitudinal dependence feature of the observed PEC's seasonal variation is not well captured by the IZMIRAN_Plas model result. Acknowledgments This research was supported by the National Natural Science Foundation of China (NSFC No. 41274163)

Compositional Variations of Paleogene and Neogene Tephra From the Northern Izu-Bonin-Mariana Arc

NASA Astrophysics Data System (ADS)

Tepley, F. J., III; Barth, A. P.; Brandl, P. A.; Hickey-Vargas, R.; Jiang, F.; Kanayama, K.; Kusano, Y.; Li, H.; Marsaglia, K. M.; McCarthy, A.; Meffre, S.; Savov, I. P.; Yogodzinski, G. M.

2014-12-01

A primary objective of IODP Expedition 351 was to evaluate arc initiation processes of the Izu-Bonin-Mariana (IBM) volcanic arc and its compositional evolution through time. To this end, a single thick section of sediment overlying oceanic crust was cored in the Amami Sankaku Basin where a complete sediment record of arc inception and evolution is preserved. This sediment record includes ash and pyroclasts, deposited in fore-arc, arc, and back-arc settings, likely associated with both the ~49-25 Ma emergent IBM volcanic arc and the evolving Ryukyu-Kyushu volcanic arc. Our goal was to assess the major element evolution of the nascent and evolving IBM system using the temporally constrained record of the early and developing system. In all, more than 100 ash and tuff layers, and pyroclastic fragments were selected from temporally resolved portions of the core, and from representative fractions of the overall core ("core catcher"). The samples were prepared to determine major and minor element compositions via electron microprobe analyses. This ash and pyroclast record will allow us to 1) resolve the Paleogene evolutionary history of the northern IBM arc in greater detail; 2) determine compositional variations of this portion of the IBM arc through time; 3) compare the acquired data to an extensive whole rock and tephra dataset from other segments of the IBM arc; 4) test hypotheses of northern IBM arc evolution and the involvement of different source reservoirs; and 5) mark important stratigraphic markers associated with the Neogene volcanic history of the adjacent evolving Ryukyu-Kyushu arc.

SSI Variations in the visible as observed with SOLAR/SOLSPEC during cycle 24 - Comparison with SORCE/SIM.

NASA Astrophysics Data System (ADS)

Irbah, A.; Damé, L.; Meftah, M.; Bekki, S.; Bolsée, D.

2017-12-01

The solar spectral irradiance (SSI) and its temporal variations are of prime importance to apprehend the physics of the Sun and to understand its effects on Earth climate through changes of atmospheric properties. Ground based measurements of SSI are indeed affected by the Earth atmosphere and space observations are therefore required to perform adequate observations. Only a few long series of SSI space measurements were obtained these last decades. The SOLSPEC instrument of the SOLAR payload on the International Space Station (ISS) has recorded one of them from April 2008 to February 2017 covering almost the whole solar cycle 24. The instrument is a spectro-radiometer recording data of the Sun from 166 to 3088 nm. Operated from the ISS in a harsh environment it needed appropriate processing methods to extract significant scientific results from noise and instrumental effects. We present the methods used to process the data to evidence visible SSI variations during cycle 24. We discuss the results obtained showing SSI variations in phase with solar activity. We compare them with SORCE/SIM measurements.

Compositional variations for alpha-galactosides in different species of leguminosae, brassicaceae, and barley: a chemotaxonomic study based on chemometrics and high-performance capillary electrophoresis.

PubMed

Andersen, Keld Ejdrup; Bjergegaard, Charlotte; Møller, Peter; Sørensen, Jens Christian; Sørensen, Hilmer

2005-07-13

The contents of raffinose family oligosaccharides (RFO) and sucrose in Brassica, Lupinus, Pisum, and Hordeum species were investigated by chemometric principal component analysis (PCA). Hordeum samples contained sucrose and raffinose, and Brassica samples all contained sucrose, raffinose, and stachyose. In addition to these, the Pisum samples contained verbascose and the Lupinus samples also contained ajugose. High stachyose and low ajugose contents were found in Lupinus albus in contrast to Lupinus angustifolius, having low stachyose and high ajugose contents. Lupinus luteus had average stachyose and ajugose contents, whereas large amounts of verbascose were accumulated in these seeds. Lupinus mutabilis had high stachyose and low ajugose contents, similar to the composition in L. albus but showing higher raffinose content. The Brassica samples also showed compositional RFO variations within the species, and subgroup formations were discovered within the investigated Brassica napus varieties. PCA results indicated compositional variations between the investigated genera and within the various species of value as chemotaxonomic defined parameters and as tools in evaluations of authenticity/falsifications when RFO-containing plants are used as, for example, feed and food additives.

Spatial and Temporal Variations of Surface Characteristics on the Greenland Ice Sheet as Derived from Passive Microwave Observations

NASA Technical Reports Server (NTRS)

Anderson, Mark; Rowe, Clinton; Kuivinen, Karl; Mote, Thomas

1996-01-01

The primary goals of this research were to identify and begin to comprehend the spatial and temporal variations in surface characteristics of the Greenland ice sheet using passive microwave observations, physically-based models of the snowpack and field observations of snowpack and firn properties.

The impact of nectar chemical features on phenotypic variation in two related nectar yeasts.

PubMed

Pozo, María I; Herrera, Carlos M; Van den Ende, Wim; Verstrepen, Kevin; Lievens, Bart; Jacquemyn, Hans

2015-06-01

Floral nectars become easily colonized by microbes, most often species of the ascomycetous yeast genus Metschnikowia. Although it is known that nectar composition can vary tremendously among plant species, most probably corresponding to the nutritional requirements of their main pollinators, far less is known about how variation in nectar chemistry affects intraspecific variation in nectarivorous yeasts. Because variation in nectar traits probably affects growth and abundance of nectar yeasts, nectar yeasts can be expected to display large phenotypic variation in order to cope with varying nectar conditions. To test this hypothesis, we related variation in the phenotypic landscape of a vast collection of nectar-living yeast isolates from two Metschnikowia species (M. reukaufii and M. gruessii) to nectar chemical traits using non-linear redundancy analyses. Nectar yeasts were collected from 19 plant species from different plant families to include as much variation in nectar chemical traits as possible. As expected, nectar yeasts displayed large variation in phenotypic traits, particularly in traits related to growth performance in carbon sources and inhibitors, which was significantly related to the host plant from which they were isolated. Total sugar concentration and relative fructose content significantly explained the observed variation in the phenotypic profile of the investigated yeast species, indicating that sugar concentration and composition are the key traits that affect phenotypic variation in nectarivorous yeasts. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Semiannual and solar activity variations of daytime plasma observed by DEMETER in the ionosphere-plasmasphere transition region

NASA Astrophysics Data System (ADS)

Li, L. Y.; Cao, J. B.; Yang, J. Y.; Berthelier, J. J.; Lebreton, J.-P.

2015-12-01

Using the plasma data of Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions (DEMETER) satellite and the NRLMSISE-00 atmospheric model, we examined the semiannual and solar activity variations of the daytime plasma and neutral composition densities in the ionosphere-plasmasphere transition region (~670-710 km). The results demonstrate that the semiannually latitudinal variation of the daytime oxygen ions (O+) is basically controlled by that of neutral atomic oxygen (O), whereas the latitude distributions of the helium and hydrogen ions (He+ and H+) do not fully depend on the neutral atomic helium (He) and hydrogen (H). The summer enhancement of the heavy oxygen ions is consistent with the neutral O enhancement in the summer hemisphere, and the oxygen ion density has significantly the summer-dense and winter-tenuous hemispheric asymmetry with respect to the dip equator. Although the winter enhancements of the lighter He+ and H+ ions are also associated with the neutral He and H enhancements in the winter hemisphere, the high-density light ions (He+ and H+) and electrons (e-) mainly appear at the low and middle magnetic latitudes (|λ| < 50°). The equatorial accumulations of the light plasma species indicate that the light charged particles (He+, H+, and e-) are easily transported by some equatorward forces (e.g., the magnetic mirror force and centrifugal force). The frequent Coulomb collisions between the charged particles probably lead to the particle trappings at different latitudes. Moreover, the neutral composition densities also influence their ion concentrations during different solar activities. From the low-F10.7 year (2007-2008) to the high-F10.7 year (2004-2005), the daytime oxygen ions and electrons increase with the increasing neutral atomic oxygen, whereas the daytime hydrogen ions tend to decrease with the decreasing neutral atomic hydrogen. The helium ion density has no obvious solar activity variation, suggesting that the

Compositional variations and differential diagenesis in Miocene turbidites from the western coast of Mallorca (Balearic Islands, Spain)

NASA Astrophysics Data System (ADS)

Felder, Sonja; Westphal, Hildegard; Munnecke, Axel; Mateu Vicens, Guillem

2010-05-01

Compositional variations and differential diagenesis in Miocene turbidites from the western coast of Mallorca (Balearic Islands, Spain) Sonja Felder (1), Hildegard Westphal (1), Axel Munnecke (2), Guillem Mateu Vicens (1,3) (1) MARUM and Department of Geosciences, Universität Bremen, Leobener Straße, 28359 Bremen, Germany (2) GeoZentrum Nordbayern, Universität Erlangen-Nürnberg, Loewenichstr. 28, 91054 Erlangen, Germany (3) Dipartimento di Scienze della Terra, Università di Roma "La Sapienza", Ple Aldo 7 Moro, 5. I-00185 Roma, Italy Cyclic alternations of limestone and marl beds crop out along the western coast of the Island of Mallorca. This Miocene succession is traditionally interpreted to represent more weathering-resistant turbidites interlayered by softer hemipelagic background sediment. However, the cementation patterns that dominate the appearance of the outcrop do not always consistently follow sedimentary layering; locally the cemented beds are systematically oblique to the sedimentary layers. Compositional studies demonstrate that differences in non-carbonate fraction, carbonate concentration and fossil content (e.g. foraminiferal assemblages) trace sedimentary bedding, regardless the diagenetic style. Limestone versus marl lithology, in contrast, is defined by the diagenetic style, tight cementation by calcite cements in the limestones versus low porosity and compaction in the marls. The reason for this striking pattern of diagenetic bedding cross-cutting sedimentary layers is assumed to be related to tectonic fracturing, opening pathways for diagenetic fluids. This example cautions the straight-forward interpretation of limestone-marl alternations as direct witnesses of environmental or climatic variations.

Spacecraft measurements of the elemental and isotopic composition of solar energetic particles

NASA Technical Reports Server (NTRS)

Mewaldt, R. A.

1980-01-01

Within the past few years, instruments flown on satellites and space probes have made significant progress in measuring the elemental and isotopic composition of energetic heavy nuclei accelerated in solar flares. These new observations are discussed, focusing on: (1) the energy dependence of the elemental composition at energies not greater than 1 MeV/nucleon; (2) flare to flare variations in the composition; and (3) comparisons of the average solar particle abundances (Z not less than 2 and not greater than 28) with other measures of the solar composition, including photospheric, coronal, and solar wind observations. These comparisons have led to the suggestion that solar flares sample the composition of the corona. Isotopic measurements of heavy solar flare nuclei have recently added a new dimension to these studies. In particular, the isotopic composition of solar flare neon has been found to be significantly different from that measured in the solar wind, but consistent with the meteoritic component neon-A.

Links between Natural Variation in the Microbiome and Host Fitness in Wild Mammals.

PubMed

Suzuki, Taichi A

2017-10-01

Recent studies in model organisms have shown that compositional variation in the microbiome can affect a variety of host phenotypes including those related to digestion, development, immunity, and behavior. Natural variation in the microbiome within and between natural populations and species may also affect host phenotypes and thus fitness in the wild. Here, I review recent evidence that compositional variation in the microbiome may affect host phenotypes and fitness in wild mammals. Studies over the last decade indicate that natural variation in the mammalian microbiome may be important in the assistance of energy uptake from different diet types, detoxification of plant secondary compounds, protection from pathogens, chemical communication, and behavior. I discuss the importance of combining both field observations and manipulative experiments in a single system to fully characterize the functions and fitness effects of the microbiome. Finally, I discuss the evolutionary consequences of mammal-microbiome associations by proposing a framework to test how natural selection on hosts is mediated by the microbiome. © The Author 2017. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions please email: journals.permissions@oup.com.

THERMAL PHASE VARIATIONS OF WASP-12b: DEFYING PREDICTIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cowan, Nicolas B.; Shekhtman, Louis M.; Machalek, Pavel

2012-03-01

We report Warm Spitzer full-orbit phase observations of WASP-12b at 3.6 and 4.5 {mu}m. This extremely inflated hot Jupiter is thought to be overflowing its Roche lobe, undergoing mass loss and accretion onto its host star, and has been claimed to have a C/O ratio in excess of unity. We are able to measure the transit depths, eclipse depths, thermal and ellipsoidal phase variations at both wavelengths. The large-amplitude phase variations, combined with the planet's previously measured dayside spectral energy distribution, are indicative of non-zero Bond albedo and very poor day-night heat redistribution. The transit depths in the mid-infrared-(R{sub p}more » /R{sub *}){sup 2} = 0.0123(3) and 0.0111(3) at 3.6 and 4.5 {mu}m, respectively-indicate that the atmospheric opacity is greater at 3.6 than at 4.5 {mu}m, in disagreement with model predictions, irrespective of C/O ratio. The secondary eclipse depths are consistent with previous studies: F{sub day}/F{sub *} = 0.0038(4) and 0.0039(3) at 3.6 and 4.5 {mu}m, respectively. We do not detect ellipsoidal variations at 3.6 {mu}m, but our parameter uncertainties-estimated via prayer-bead Monte Carlo-keep this non-detection consistent with model predictions. At 4.5 {mu}m, on the other hand, we detect ellipsoidal variations that are much stronger than predicted. If interpreted as a geometric effect due to the planet's elongated shape, these variations imply a 3:2 ratio for the planet's longest:shortest axes and a relatively bright day-night terminator. If we instead presume that the 4.5 {mu}m ellipsoidal variations are due to uncorrected systematic noise and we fix the amplitude of the variations to zero, the best-fit 4.5 {mu}m transit depth becomes commensurate with the 3.6 {mu}m depth, within the uncertainties. The relative transit depths are then consistent with a solar composition and short scale height at the terminator. Assuming zero ellipsoidal variations also yields a much deeper 4.5 {mu}m eclipse depth

Spatio-temporal variation in chemical characteristics of PM10 over Indo Gangetic Plain of India.

PubMed

Sharma, S K; Mandal, T K; Srivastava, M K; Chatterjee, A; Jain, Srishti; Saxena, M; Singh, B P; Saraswati; Sharma, A; Adak, A; K Ghosh, S

2016-09-01

The paper presents the spatio-temporal variation of chemical compositions (organic carbon (OC), elemental carbon (EC), and water-soluble inorganic ionic components (WSIC)) of particulate matter (PM10) over three locations (Delhi, Varanasi, and Kolkata) of Indo Gangetic Plain (IGP) of India for the year 2011. The observational sites are chosen to represent the characteristics of upper (Delhi), middle (Varanasi), and lower (Kolkata) IGP regions as converse to earlier single-station observation. Average mass concentration of PM10 was observed higher in the middle IGP (Varanasi 206.2 ± 77.4 μg m(-3)) as compared to upper IGP (Delhi 202.3 ± 74.3 μg m(-3)) and lower IGP (Kolkata 171.5 ± 38.5 μg m(-3)). Large variation in OC values from 23.57 μg m(-3) (Delhi) to 12.74 μg m(-3) (Kolkata) indicating role of formation of secondary aerosols, whereas EC have not shown much variation with maximum concentration over Delhi (10.07 μg m(-3)) and minimum over Varanasi (7.72 μg m(-3)). As expected, a strong seasonal variation was observed in the mass concentration of PM10 as well as in its chemical composition over the three locations. Principal component analysis (PCA) identifies the contribution of secondary aerosol, biomass burning, fossil fuel combustion, vehicular emission, and sea salt to PM10 mass concentration at the observational sites of IGP, India. Backward trajectory analysis indicated the influence of continental type aerosols being transported from the Bay of Bengal, Pakistan, Afghanistan, Rajasthan, Gujarat, and surrounding areas to IGP region.

The time variation of atomic oxygen emission around Io during a volcanic event observed with Hisaki/EXCEED

NASA Astrophysics Data System (ADS)

Koga, Ryoichi; Tsuchiya, Fuminori; Kagitani, Masato; Sakanoi, Takeshi; Yoneda, Mizuki; Yoshioka, Kazuo; Kimura, Tomoki; Murakami, Go; Yamazaki, Atsushi; Yoshikawa, Ichiro; Smith, H. Todd

2018-01-01

Io has an atmosphere produced by volcanism and sublimation of frosts deposited around active volcanoes. However, the time variation of atomic oxygen escaping Io's atmosphere is not well known. In this paper, we show a significant increase in atomic oxygen around Io during a volcanic event. Brightening of Io's extended sodium nebula was observed in the spring of 2015. We used the Hisaki satellite to investigate the time variation of atomic oxygen emission around Io during the same period. This investigation reveals that the duration of atomic oxygen brightness increases from a volcanically quiet level to a maximum level during the same approximate time period of 30 days as the observed sodium brightness. On the other hand, the recovery of the atomic oxygen brightness from the maximum to the quiet level (60 days) was longer than that of the sodium nebula decreasing (40 days). Additionally, a dawn-dusk asymmetry of the atomic oxygen emission is observed.

Planetary and meteoritic Mg/Si and δ30 Si variations inherited from solar nebula chemistry

NASA Astrophysics Data System (ADS)

Dauphas, Nicolas; Poitrasson, Franck; Burkhardt, Christoph; Kobayashi, Hiroshi; Kurosawa, Kosuke

2015-10-01

The bulk chemical compositions of planets are uncertain, even for major elements such as Mg and Si. This is due to the fact that the samples available for study all originate from relatively shallow depths. Comparison of the stable isotope compositions of planets and meteorites can help overcome this limitation. Specifically, the non-chondritic Si isotope composition of the Earth's mantle was interpreted to reflect the presence of Si in the core, which can also explain its low density relative to pure Fe-Ni alloy. However, we have found that angrite meteorites display a heavy Si isotope composition similar to the lunar and terrestrial mantles. Because core formation in the angrite parent-body (APB) occurred under oxidizing conditions at relatively low pressure and temperature, significant incorporation of Si in the core is ruled out as an explanation for this heavy Si isotope signature. Instead, we show that equilibrium isotopic fractionation between gaseous SiO and solid forsterite at ∼1370 K in the solar nebula could have produced the observed Si isotope variations. Nebular fractionation of forsterite should be accompanied by correlated variations between the Si isotopic composition and Mg/Si ratio following a slope of ∼1, which is observed in meteorites. Consideration of this nebular process leads to a revised Si concentration in the Earth's core of 3.6 (+ 6.0 / - 3.6) wt% and provides estimates of Mg/Si ratios of bulk planetary bodies.

Early 2017 observations of TRAPPIST-1 with Spitzer

NASA Astrophysics Data System (ADS)

Delrez, L.; Gillon, M.; Triaud, A. H. M. J.; Demory, B.-O.; de Wit, J.; Ingalls, J. G.; Agol, E.; Bolmont, E.; Burdanov, A.; Burgasser, A. J.; Carey, S. J.; Jehin, E.; Leconte, J.; Lederer, S.; Queloz, D.; Selsis, F.; Van Grootel, V.

2018-04-01

The recently detected TRAPPIST-1 planetary system, with its seven planets transiting a nearby ultracool dwarf star, offers the first opportunity to perform comparative exoplanetology of temperate Earth-sized worlds. To further advance our understanding of these planets' compositions, energy budgets, and dynamics, we are carrying out an intensive photometric monitoring campaign of their transits with the Spitzer Space Telescope. In this context, we present 60 new transits of the TRAPPIST-1 planets observed with Spitzer/Infrared Array Camera (IRAC) in 2017 February and March. We combine these observations with previously published Spitzer transit photometry and perform a global analysis of the resulting extensive data set. This analysis refines the transit parameters and provides revised values for the planets' physical parameters, notably their radii, using updated properties for the star. As part of our study, we also measure precise transit timings that will be used in a companion paper to refine the planets' masses and compositions using the transit timing variations method. TRAPPIST-1 shows a very low level of low-frequency variability in the IRAC 4.5-μm band, with a photometric RMS of only 0.11 per cent at a 123-s cadence. We do not detect any evidence of a (quasi-)periodic signal related to stellar rotation. We also analyse the transit light curves individually, to search for possible variations in the transit parameters of each planet due to stellar variability, and find that the Spitzer transits of the planets are mostly immune to the effects of stellar variations. These results are encouraging for forthcoming transmission spectroscopy observations of the TRAPPIST-1 planets with the James Webb Space Telescope.

Compositional variations in sands of the Bagnold Dunes, Gale Crater, Mars, from visible-shortwave infrared spectroscopy and comparison with ground truth from the Curiosity Rover

USGS Publications Warehouse

Lapotre, Mathieu G.A.; Ehlmann, B. L.; Minson, Sarah E.; Arvidson, R. E.; Ayoub, F.; Fraeman, A. A.; Ewing, R. C.; Bridges, N. T.

2017-01-01

During its ascent up Mount Sharp, the Mars Science Laboratory Curiosity rover traversed the Bagnold Dune Field. We model sand modal mineralogy and grain size at four locations near the rover traverse, using orbital shortwave infrared single scattering albedo spectra and a Markov-Chain Monte Carlo implementation of Hapke's radiative transfer theory to fully constrain uncertainties and permitted solutions. These predictions, evaluated against in situ measurements at one site from the Curiosity rover, show that XRD-measured mineralogy of the basaltic sands is within the 95% confidence interval of model predictions. However, predictions are relatively insensitive to grain size and are non-unique, especially when modeling the composition of minerals with solid solutions. We find an overall basaltic mineralogy and show subtle spatial variations in composition in and around the Bagnold dunes, consistent with a mafic enrichment of sands with cumulative transport distance by sorting of olivine, pyroxene, and plagioclase grains during aeolian saltation. Furthermore, the large variations in Fe and Mg abundances (~20 wt%) at the Bagnold Dunes suggest that compositional variability induced by wind sorting may be enhanced by local mixing with proximal sand sources. Our estimates demonstrate a method for orbital quantification of composition with rigorous uncertainty determination and provide key constraints for interpreting in situ measurements of compositional variability within martian aeolian sandstones.

Using ACE Observations of Interplanetary Particles and Magnetic Fields as Possible Contributors to Variations Observed at Van Allen Probes during Major events in 2013

NASA Astrophysics Data System (ADS)

Armstrong, T. P.; Manweiler, J. W.; Gerrard, A. J.; Gkioulidou, M.; Lanzerotti, L. J.; Patterson, J. D.

2013-12-01

Observations from ACE EPAM including energy spectra of protons, helium, and oxygen will be prepared for coordinated use in estimating the direct and indirect access of energetic particles to inner and outer geomagnetic trapping zones. Complete temporal coverage from ACE at 12 seconds, 5 minutes, 17 minutes, hourly and daily cadences will be used to catalog interplanetary events arriving at Earth including interplanetary magnetic field sector boundaries, interplanetary shocks, and interplanetary coronal mass ejections, ICMEs. The first 6 months of 2013 have included both highly disturbed times, March 17 and May 22, and extended quiet periods of little or no variations. Among the specific questions that ACE and Van Allen Probes coordinated observations may aid in resolving are: 1. How much, if any, direct capture of interplanetary energetic particles occurs and what conditions account for it? 2. How much influence do interplanetary field and particle variations have on energization and/or loss of geomagnetically trapped populations? The poster will also present important links and describe methods and important details of access to numerically expressed ACE EPAM and Van Allen Probes RBSPICE observations that can be flexibly and easily accessed via the internet for student and senior researcher use.

Thermospheric temperature, density, and composition: New models

NASA Technical Reports Server (NTRS)

Jacchia, L. G.

1977-01-01

The models essentially consist of two parts: the basic static models, which give temperature and density profiles for the relevant atmospheric constituents for any specified exospheric temperature, and a set of formulae to compute the exospheric temperature and the expected deviations from the static models as a result of all the recognized types of thermospheric variation. For the basic static models, tables are given for heights from 90 to 2,500 km and for exospheric temperatures from 500 to 2600 K. In the formulae for the variations, an attempt has been made to represent the changes in composition observed by mass spectrometers on the OGO 6 and ESRO 4 satellites.

Inter- and intra-group compositional variations in Apollo 15 pyroclastic green glass - An electron- and ion-microprobe study

NASA Technical Reports Server (NTRS)

Galbreath, K. C.; Shearer, C. K.; Papike, J. J.; Shimizu, N.

1990-01-01

Results are presented on major- and trace-element abundance analyses of Apollo 15 pyroclastic green glasses from groups A, B, C, D, and E, carried out using electron- and ion-microprobe techniques. The diagrams depicting Sr, Zr, Ba, and Nd vs Co variations indicate the presence of a high-Co trend in groups A and D and a low-Co trend in groups B and C. Group-E glasses were found to be significantly enriched in Sr, relative to the other four glass groups. Chemical data of this study were integrated with previous data to evaluate various magmatic processes that have been proposed in the past to explain chemical variations in the lunar green glass. Results of calculations using a source mixing model suggest that the Apollo 15 green glasses represent multiple eruptive events from three chemically distinct but compositionally variable source regions.

Phylogenetic Diversity in the Macromolecular Composition of Microalgae

PubMed Central

Finkel, Zoe V.; Follows, Mick J.; Liefer, Justin D.; Brown, Chris M.; Benner, Ina; Irwin, Andrew J.

2016-01-01

The elemental stoichiometry of microalgae reflects their underlying macromolecular composition and influences competitive interactions among species and their role in the food web and biogeochemistry. Here we provide a new estimate of the macromolecular composition of microalgae using a hierarchical Bayesian analysis of data compiled from the literature. The median macromolecular composition of nutrient-sufficient exponentially growing microalgae is 32.2% protein, 17.3% lipid, 15.0% carbohydrate, 17.3% ash, 5.7% RNA, 1.1% chlorophyll-a and 1.0% DNA as percent dry weight. Our analysis identifies significant phylogenetic differences in macromolecular composition undetected by previous studies due to small sample sizes and the large inherent variability in macromolecular pools. The phylogenetic differences in macromolecular composition lead to variations in carbon-to-nitrogen ratios that are consistent with independent observations. These phylogenetic differences in macromolecular and elemental composition reflect adaptations in cellular architecture and biochemistry; specifically in the cell wall, the light harvesting apparatus, and storage pools. PMID:27228080

Long-time variation in magnetic structure of CeIr 3Si 2: Observation of a nucleation-and-growth process of magnetic domains

DOE PAGES

Motoya, Kiyoichiro; Hagihala, Masato; Takabatake, Toshiro; ...

2016-02-29

CeIr 3Si 2 is the first three-dimensional uniform magnet in which the long-time variation in magnetic structure was observed. To clarify the microscopic mechanism of this magnetic structural change, time-resolved neutron scattering measurements have been reinvestigated. Clear time variations in the line widths as well as the amplitudes of magnetic Bragg diffractions have been observed in this improved instrumentation. On the notion of this observation, a nucleation-and-growth model of magnetic structural change has been presented. The numerical calculation with this model reproduces well the observation.

Long-time variation in magnetic structure of CeIr 3Si 2: Observation of a nucleation-and-growth process of magnetic domains

DOE Office of Scientific and Technical Information (OSTI.GOV)

Motoya, Kiyoichiro; Hagihala, Masato; Takabatake, Toshiro

CeIr 3Si 2 is the first three-dimensional uniform magnet in which the long-time variation in magnetic structure was observed. To clarify the microscopic mechanism of this magnetic structural change, time-resolved neutron scattering measurements have been reinvestigated. Clear time variations in the line widths as well as the amplitudes of magnetic Bragg diffractions have been observed in this improved instrumentation. On the notion of this observation, a nucleation-and-growth model of magnetic structural change has been presented. The numerical calculation with this model reproduces well the observation.

IUE observations of longitudinal and temporal variations in the Jovian auroral emission

NASA Technical Reports Server (NTRS)

Skinner, T. E.; Durrance, S. T.; Feldman, P. D.; Moos, H. W.

1984-01-01

The IUE's short wavelength spectrograph has been used to monitor the auroral emissions from Jupiter's northern hemisphere, yielding eight observations between January 1981 and January 1982 of H I Lyman-alpha and the H2 Lyman and Werner bands. Attention is given to an apparent periodic emission flux fluctuation, through detailed modeling of the emission geometry. Two possible auroral zones are defined at the north pole by mapping the magnetic field lines from the Io torus and the magnetotail onto the planet's atmosphere. The observed variation in flux with central meridian longitude is not consistent with a uniform brightness as a function of magnetic longitude in either auroral zone. The data can be fitted by confining the emissions to the region of the northern torus auroral zone, in qualitative agreement with the magnetic anomaly model. A similar emission from the magnetotail auroral zone cannot be ruled out.

Spatial variation of dissolved organic matter composition and characteristics in an urbanized watershed

NASA Astrophysics Data System (ADS)

Hsieh, C.; Li, M.

2013-12-01

Dissolved organic matter (DOM) is a chemically complex mixture of organic polymers that plays an important role in river ecosystems and originates from various sources. Some DOMs are autochthonous originating through phytoplankton and microbial activity in situ. On the other hand, some DOMs are allochthonous which are transported to river from the surrounding watershed by natural or anthropogenic activities. The studies of DOM in river are usually conducted at the watershed scale; however, factors of local spatial scale affecting DOM composition also need to take into consideration for the study of DOM in an urbanized watershed. Through increasing urbanization, changes in a watershed occur not only in land use patterns but also in river channel characteristics. The objective of this study is to investigate effects of different river channel characteristics and patterns on changes in DOM source and composition. In this study, we chose three tributaries of Tamsui river in Taiwan according to its land use pattern and river channel characteristics. At each sub-basin, river water samples were sampled from three study sites. River water DOM was measured by using optical measurements of UV absorption and fluorescence spectroscopy. Water samples were also collected for laboratory analysis of different water quality parameters. From our study sites, they are from three sub-basins which are in the similar physical environments but with different river channel types: the highly channelized Keelung river, the less channelized Xindian river, and less channelized Dahan river with five human-made wetlands. From the upstream to the urbanized downstream, composition of DOM showed variation among different sampled sites. In all three sub-basins, the trends of 5-day biochemical oxygen demand (BOD5) and suspended solids (SS) are also different. The changes in DOM source and composition as well as different water quality parmaters occur at the local spatial-scale depended on their

Morphology variation, composition alteration and microstructure changes in ion-irradiated 1060 aluminum alloy

NASA Astrophysics Data System (ADS)

Wan, Hao; Si, Naichao; Wang, Quan; Zhao, Zhenjiang

2018-02-01

Morphology variation, composition alteration and microstructure changes in 1060 aluminum irradiated with 50 keV helium ions were characterized by field emission scanning electron microscopy (FESEM) equipped with x-ray elemental scanning, 3D measuring laser microscope and transmission electron microscope (TEM). The results show that, helium ions irradiation induced surface damage and Si-rich aggregates in the surfaces of irradiated samples. Increasing the dose of irradiation, more damages and Si-rich aggregates would be produced. Besides, defects such as dislocations, dislocation loops and dislocation walls were the primary defects in the ion implanted layer. The forming of surface damages were related with preferentially sputtering of Al component. While irradiation-enhanced diffusion and irradiation-induced segregation resulted in the aggregation of impurity atoms. And the aggregation ability of impurity atoms were discussed based on the atomic radius, displacement energy, lattice binding energy and surface binding energy.

Diurnal variation of O3, ClO, HOCl, HO2, and BrO observed by JEM/SMILES

NASA Astrophysics Data System (ADS)

Suzuki, Makoto; Mitsuda, Chihiro; Manago, Naohiro; Imai, Koji; Sakazaki, Takatoshi; Ozeki, Hiroyuki; Nishimoto, Eriko; Naito, Yoko; Akiyoshi, Hidehary; Kinnison, Douglas; Sano, Takuki; Shiotani, Masato

2013-04-01

SMILES; Superconducting Submillimeter-Wave Limb Emission Sounder is a 4 K cooled 625-650 GHz limb sounder to observe O3, HCl, ClO, HO2, HOCl, BrO, HNO3, and O3 isotopes. SMILES had been operated on the International Space Station from Oct. 12, 2009 to Apr. 21, 2010. Since ISS is 51° inclined orbit, 30-45 days SMILES zonal mean could provide diurnal variation of chemical species in the stratosphere and mesosphere. Diurnal variation of O3, ClO, HOCl, HO2, and BrO are compared with two nudged CGCM calculations (SD-WACCM; Specified-dynamics WACCM, and MIROC) and satellite observations. Diurnal variation of O3 agreed with SD-WACCM over 50-82 km, but small peak in the morning (7 am local time) is apparent for the SMILES but not for the SD-WACCM at 70 km. Diurnal variation of ClO agreed quite well between SMILES L2 ver. 2.2 and SD-WACCM from 19 to 76 km altitude region. But nighttime ClO value of SMILES L2 ver. 2,2 above 50 km is less than SD-WACCM (70%), which is not clearly explained by the SMILES retrieval issue or our current knowledge of chemical kinetics. Diurnal variation of HOCl also agreed quite nicely from 31 to 76 km. SMILES HOCl retrieval is difficult since it is strongly affected by nearby O3 isotope and O3 hot band lines, as well as very strong HCl line. The nighttime build up of HOCl observed SMILES at 44-68 km are nicely reproduced by the SD-WACCM calculation using JPL2006 chemical kinetics dataset. But chemical kinetics calculation using SMILES ClO, HO2, and HOCl at 35-45 km altitude supported much faster reaction rate of ClO + HO2 given by JPL2010. HO2 diurnal variation also agreed with SD-WACCM from 24 to 72 km. Above 76 km, SMILES L2 ver. 2.2 needs modification of a priori and its co-variance, and we will get better agreement with model calculations. SMILES L2 ver. 2.2 also shows night time bias due to AOS (Acousto-Optics Spectrometer) characteristics. SMILES Band C BrO observation is strongly interfered by overlapping O3 isotope lines, and it is

Modeling the Observed QBO and Inter-Annual Variations of the Diurnal Tide in the Mesosphere

NASA Technical Reports Server (NTRS)

Mayr, Hans G.; Mengel, John G.; Huang, F. T.

2006-01-01

In the current version of the Numerical Spectral Model (NSM), the Quasi-biennial Oscillation (QBO) is generated primarily by small-scale gravity waves (GW) from Hines' Doppler Spread Parameterization (DSP). The model does not have topography, and the planetary waves are solely generated by instabilities. We discuss a 3D modeling study that describes the QBO extending from the stratosphere into the upper mesosphere, where the oscillation produces significant inter-annual variations in the diurnal tide. The numerical results are compared with temperature measurements from the SABER (TIMED) and MLS (UARS) instruments obtained by Huang et al. (2006). With a GW source that peaks at the Equator and is taken to be isotropic and independent of season, the NSM generates a QBO with variable periods around 26 months and zonal wind amplitudes of almost 25 m/s at 30 km. As reported earlier, the NSM reproduces the observed equinoctial maxima in the diurnal tide at altitudes around 95 km. The modeled QBO modulates the tide such that the seasonal amplitude maxima can vary from one year to another by as much as 30%. To shed light on the underlying mechanisms, the relative importance of the advection terms are discussed, and they are shown to be important in the stratosphere. At altitudes above 80 km, however, the QBO-related inter-annual variations of the tide are generated primarily by GW momentum deposition. In qualitative agreement with the SABER measurements, the model generates distinct zonal-mean QBO temperature variations in the stratosphere and mesosphere. In the stratosphere, the computed amplitudes are not much smaller than those observed, and the rate of downward propagation at the Equator is reproduced. The modeled temperature amplitudes in the mesosphere, however, are much smaller than those observed. The observed and computed temperature variations of the QBO peak at the Equator but extend with phase reversals to high latitudes, in contrast to the zonal winds that are

Berry composition and climate: responses and empirical models.

PubMed

Barnuud, Nyamdorj N; Zerihun, Ayalsew; Gibberd, Mark; Bates, Bryson

2014-08-01

Climate is a strong modulator of berry composition. Accordingly, the projected change in climate is expected to impact on the composition of berries and of the resultant wines. However, the direction and extent of climate change impact on fruit composition of winegrape cultivars are not fully known. This study utilised a climate gradient along a 700 km transect, covering all wine regions of Western Australia, to explore and empirically describe influences of climate on anthocyanins, pH and titratable acidity (TA) levels in two or three cultivars of Vitis vinifera (Cabernet Sauvignon, Chardonnay and Shiraz). The results showed that, at a common maturity of 22° Brix total soluble solids, berries from the warmer regions had low levels of anthocyanins and TA as well as high pH compared to berries from the cooler regions. Most of these regional variations in berry composition reflected the prevailing climatic conditions of the regions. Thus, depending on cultivar, 82-87 % of TA, 83 % of anthocyanins and about half of the pH variations across the gradient were explained by climate-variable-based empirical models. Some of the variables that were relevant in describing the variations in berry attributes included: diurnal ranges and ripening period temperature (TA), vapour pressure deficit in October and growing degree days (pH), and ripening period temperatures (anthocyanins). Further, the rates of change in these berry attributes in response to climate variables were cultivar dependent. Based on the observed patterns along the climate gradient, it is concluded that: (1) in a warming climate, all other things being equal, berry anthocyanins and TA levels will decline whereas pH levels will rise; and (2) despite variations in non-climatic factors (e.g. soil type and management) along the sampling transect, variations in TA and anthocyanins were satisfactorily described using climate-variable-based empirical models, indicating the overriding impact of climate on berry

Berry composition and climate: responses and empirical models

NASA Astrophysics Data System (ADS)

Barnuud, Nyamdorj N.; Zerihun, Ayalsew; Gibberd, Mark; Bates, Bryson

2014-08-01

Climate is a strong modulator of berry composition. Accordingly, the projected change in climate is expected to impact on the composition of berries and of the resultant wines. However, the direction and extent of climate change impact on fruit composition of winegrape cultivars are not fully known. This study utilised a climate gradient along a 700 km transect, covering all wine regions of Western Australia, to explore and empirically describe influences of climate on anthocyanins, pH and titratable acidity (TA) levels in two or three cultivars of Vitis vinifera (Cabernet Sauvignon, Chardonnay and Shiraz). The results showed that, at a common maturity of 22° Brix total soluble solids, berries from the warmer regions had low levels of anthocyanins and TA as well as high pH compared to berries from the cooler regions. Most of these regional variations in berry composition reflected the prevailing climatic conditions of the regions. Thus, depending on cultivar, 82-87 % of TA, 83 % of anthocyanins and about half of the pH variations across the gradient were explained by climate-variable-based empirical models. Some of the variables that were relevant in describing the variations in berry attributes included: diurnal ranges and ripening period temperature (TA), vapour pressure deficit in October and growing degree days (pH), and ripening period temperatures (anthocyanins). Further, the rates of change in these berry attributes in response to climate variables were cultivar dependent. Based on the observed patterns along the climate gradient, it is concluded that: (1) in a warming climate, all other things being equal, berry anthocyanins and TA levels will decline whereas pH levels will rise; and (2) despite variations in non-climatic factors (e.g. soil type and management) along the sampling transect, variations in TA and anthocyanins were satisfactorily described using climate-variable-based empirical models, indicating the overriding impact of climate on berry

Spatially resolved variations in reflectivity across iron oxide thin films

NASA Astrophysics Data System (ADS)

Kelley, Chris S.; Thompson, Sarah M.; Gilks, Daniel; Sizeland, James; Lari, Leonardo; Lazarov, Vlado K.; Matsuzaki, Kosuke; LeFrançois, Stéphane; Cinque, Gianfelice; Dumas, Paul

2017-11-01

The spin polarising properties of the iron oxide magnetite (Fe3O4) make it attractive for use in spintronic devices, but its sensitivity to compositional and structural variations make it challenging to prepare reliably. Infrared microspectroscopy and modelling are used to determine the spatial variation in the chemical composition of three thin films of iron oxide; one prepared by pulsed laser deposition (PLD), one by molecular beam epitaxy (MBE) deposition of iron whilst simultaneously flowing oxygen into the chamber and one by flowing oxygen only once deposition is complete. The technique is easily able to distinguish between films which contain metallic iron and different iron oxide phases as well as spatial variations in composition across the films. The film grown by post-oxidising iron is spatially uniform but not fully oxidised, the film grown by simultaneously oxidising iron showed spatial variation in oxide composition while the film grown by PLD was spatially uniform magnetite.

Changes in composition of cuticular biochemicals of the facultatively polygynous ant Petalomyrmex phylax during range expansion in Cameroon with respect to social, spatial and genetic variation.

PubMed

Dalecky, Ambroise; Renucci, Marielle; Tirard, Alain; Debout, Gabriel; Roux, Maurice; Kjellberg, Finn; Provost, Erick

2007-09-01

In social insects, biochemicals found at the surface of the cuticle are involved in the recognition process and in protection against desiccation and pathogens. However, the relative contribution of evolutionary forces in shaping diversity of these biochemicals remains largely unresolved in ants. We determined the composition of epicuticular biochemicals for workers sampled in 12 populations of the ant Petalomyrmex phylax from Cameroon. Genetic variation at 12 microsatellite markers was used to infer population history and to provide null expectations under the neutrality hypothesis. Genetic data suggest a recent southward range expansion of this ant species. Furthermore, there is a decline southward in the numbers of queens present in mature colonies. Here, we contrast the pattern of biochemical variation against genetic, social and spatial parameters. We thus provide the first estimates of the relative contribution of neutral and selective processes on variation of ant cuticular profile. Populations in migration-drift disequilibrium showed reduction of within-population variation for genetic markers as well as for cuticular profiles. In these populations, the cuticular profile became biased towards a limited number of high molecular weight molecules. Within- and among-population biochemical variation was explained by both genetic and social variation and by the spatial distribution of populations. We therefore propose that during range expansion of P. phylax, the composition of epicuticular compounds has been affected by a combination of neutral processes - genetic drift and spatially limited dispersal - and spatially varying selection, social organization and environmental effects.

Seasonal variation of plankton communities influenced by environmental factors in an artificial lake

NASA Astrophysics Data System (ADS)

Li, Xuemei; Yu, Yuhe; Zhang, Tanglin; Feng, Weisong; Ao, Hongyi; Yan, Qingyun

2012-05-01

We evaluated the seasonal variation in plankton community composition in an artificial lake. We conducted microscopic analysis and denaturing gradient gel electrophoresis (DGGE) of PCR-amplified partial 16S rRNA and 18S rRNA genes to characterize the plankton community. The clustering of unweighted pair group method with arithmetic mean (UPGMA) was then used to investigate the similarity of these plankton communities. DGGE fingerprinting revealed that samples collected at the different sites within a season shared high similarity and were generally grouped together. In contrast, we did not observe any seasonal variation based on microscopic analysis. Redundancy analysis (RDA) of the plankton operational taxonomic units (OTUs) in relation to environmental factors revealed that transparency was negatively correlated with the first axis ( R=-0.931), and temperature and total phosphorus (TP) were positively correlated with the first axis ( R=0.736 and R=0.660, respectively). In conclusion, plankton communities in the artificial lake exhibited significant seasonal variation. Transparency, phosphorus and temperature appear to be the major factors driving the differences in plankton composition.

The composition of Martian aeolian sands: Thermal emissivity from Viking IRTM observations

NASA Technical Reports Server (NTRS)

Edgett, Kenneth S.; Christensen, Philip R.

1992-01-01

Aeolian sands provide excellent surfaces for the remote determination of the mineralogic composition of Martian materials, because such deposits consist of relatively well-sorted, uniform particle sizes and might consist of chemically unaltered, primary mineral grains derived from bedrock. Dark features on the floors of Martian craters are controlled by aeolian processes and many consist largely of unconsolidated, windblown sand. Measurement of the thermal emissivity of geologic materials provides a way to identify mid-infrared absorption bands, the strength and positions of which vary with mineral structure and composition. The Viking Infrared Thermal Mapper (IRTM) had four surface-sensing mid-IR bands, three of which, the 7, 9, and 11 micron channels, correspond to absorption features characteristic of carbonates, sialic, and mafic minerals, respectively. In this study, the highest quality IRTM data were constrained so as to avoid the effects of atmospheric dust, clouds, surface frosts, and particle size variations (the latter using data obtained between 7 and 9 H, and they were selected for dark intracrater features such that only data taken directly from the dark feature were used, so as to avoid thermal contributions from adjacent but unrelated materials. Three-point emissivity spectra of Martian dart intracrater features were compared with laboratory emission spectra of minerals and terrestrial aeolian sands convolved using the IRTM response function to the four IRTM spectral channels.

Compositional variation in minerals of the chevkinite group

USGS Publications Warehouse

Macdonald, R.; Belkin, H.E.

2002-01-01

The composition of chevkinite and perrierite, the most common members of the chevkinite group, is closely expressed by the formula A4BC2D2Si4O22, where A = (La,Ce,Ca,Sr,Th), B = Fe2+, C = (Fe2+,Fe3+,Ti,Al,Zr,Nb) and D = Ti. The A site is dominated by a strong negative correlation between (Ca+Sr) and the REE. Chondrite-normalized REE patterns are very variable, e.g. in LREE/HREE and Eu/Eu*. The C site is dominated by Ti, Al and Fe2+, in very variable proportions. Most chevkinites and perrierites are close to stoichiometric, with cation sums between 12.9 and 13.5, compared to the theoretical 13. There is no single, generally applicable charge balancing substitution scheme in the group; however, the general relationship (Ca+Sr)A + TiC + REEA + M3C+2+ defines a linear array with r2 = 0.91. Chevkinite and perrierite are shown to be compositionally distinct on the basis of CaO, FeO* Al2O3 and Ce2O3 abundances. Chevkinite forms mainly in chemically evolved parageneses, such as syenites, rhyolites and fenites associated with carbonatite complexes. Perrierite is more commonly recorded from igneous rocks of mafic to intermediate composition. The compositional characteristics and possible structural formulae of other members of the chevkinite group are reviewed briefly.

Slumping during sculpturing of composite materials.

PubMed

Chiang, Yu-Chih; Knezevic, Alena; Kunzelmann, Karl-Heinz

2008-12-01

This study investigated the slumping characteristics of four composite materials during sculpturing prior to their polymerization. Four different composite materials were used to measure shape deformation due to slumping. Silicon impressions of the occlusal plane of three different molars were used as a mould for the composite samples. The surface of the samples was digitized with a laser scanner (400 slices, lateral resolution: 25 microm). Scans were made after 1-4 min. The 3D data sets were numerically superimposed with matching software and differences were calculated relative to the baseline measurement. The amount of surface deformation increases with increasing observation time. The average coefficient of variation was 0.2. The largest mean amount of slumping was observed for ELS with tooth mould 1 (150.0 microm), and for Clearfil Majesty with tooth mould 2 (98.3 microm) and mould 3 (42.8 microm). Miris 2 Dentin and Synergy D6 Enamel were rather similar and seem to exhibit little deformation. The slump flow of ELS and Clearfil Majesty was up to 400% higher than the formers. The deformation could be sorted in the following order "mould 3"<"mould 2"<"mould 1" for all materials and all observation time. There was a significant influence (p<0.05) of the three factors, time, mould and composite type (ANOVA). This specific method provides a reproducible approach for the assessment of the handling characteristics of composite materials. The results can identify slumping differences and assist in collecting information about the feasibility of a material for certain indications.

SNR improvement by variation of recording and media parameters for a HAMR exchange coupled composite media

NASA Astrophysics Data System (ADS)

Natekar, N. A.; Liu, Zengyuan; Hernandez, Stephanie; Victora, R. H.

2018-05-01

An exchange coupled composite media structure proposed previously seems to address both the issue of Tc variation in FePt as well as poor SNR/User Density during the HAMR process. Here we examine a thinner 3-6 nm structure that is likely easier to fabricate than the previous 13.5 nm thick structure. We find that increasing the damping within the write (superparamagnetic) layer and introducing intergranular exchange within the grains in the write layer are both successful approaches to improve the recorded SNR. Ensemble waveform analysis that allows the breakdown of the total SNR into transition SNR (due to AC noise) and remanence SNR (due to DC noise) helps identify the leading causes for this SNR improvement. Further studies indicate that varying the peak heat spot temperature in the HAMR write process is also a successful approach for improving the recorded SNR. This lends credence to the idea that a thinner composite media may still be used successfully to realize significant enhancements of SNR and the corresponding user density.

Compositional Mapping of the Transantarctic Mountains Using Orbital Reflectance Data

NASA Astrophysics Data System (ADS)

Salvatore, M. R.; Niebuhr, S.; Morin, P. J.; Cox, S.

2014-12-01

We report on our progress of remotely mapping compositional variations throughout the Transantarctic Mountains (TAM) using orbital spectroscopic data. These techniques were originally proven effective in Antarctica using moderate spatial resolution (30 m/pixel) Advanced Land Imager (ALI) data, and showed great successes in identifying even minor variations in composition throughout the McMurdo Dry Valleys (MDV) [Salvatore et al., 2013]. However, due to the orbital inclination of the Earth Observing-1 spacecraft, ALI is unable to image the central and southern TAM, making comparable studies at comparable resolutions impossible on a continental scale. Fortunately, the WorldView-2 satellite (DigitalGlobe, Inc.) boasts high-resolution (2 m/pixel) multispectral capabilities, with 8 spectral bands located between 427 nm and 908 nm, and is able to image the entirety of the TAM through off-nadir pointing capabilities. This provides the ability to continue our remote spectral mapping campaign throughout the TAM to identify compositional variations in support of past and future field operations. We present an updated map of relative spectral variability (RSV) in the vicinity of Shackleton Glacier. This mapping product consists of 91 individual WorldView-2 images, each corrected to top-of-atmosphere radiance and parameterized to highlight known compositional properties. The mapped area covers approximately 17,850 square kilometers of ice-covered and exposed terrain. Compositional variations are easily mapped, and small-scale variations in iron-bearing mineralogy are particularly well resolved. We also describe our updated atmospheric correction algorithm for the WorldView-2 dataset, which utilizes in-scene techniques to derive surface reflectance and does not necessitate the use of radiative transfer modeling. Our technique is validated using laboratory reflectance measurements. In conjunction with the Polar Rock Repository at the Ohio State University, we have measured

Thermal degradation of the tensile strength of unidirectional boron/aluminum composites

NASA Technical Reports Server (NTRS)

Grimes, H. H.; Lad, R. A.; Maisel, J. E.

1977-01-01

The variation of ultimate tensile strength with thermal treatment of B-Al composite materials and of boron fibers chemically removed from these composites in an attempt to determine the mechanism of the resulting strength degradation was studied. Findings indicate that thermally cycling B-Al represents a more severe condition than equivalent time at temperature. Degradation of composite tensile strength from about 1.3 GN/m squared to as low as 0.34 GN/m squared was observed after 3,000 cycles to 420 C for 203 micrometers B-1100 Al composite. In general, the 1100 Al matrix composites degraded somewhat more than the 6061 matrix material studied. Measurement of fiber strengths confirmed a composite strength loss due to the degradation of fiber strength. Microscopy indicated a highly flawed fiber surface.

Thermo-Active Behavior of Ethylene-Vinyl Acetate | Multiwall Carbon Nanotube Composites Examined by in Situ near-Edge X-ray Absorption Fine-Structure Spectroscopy

PubMed Central

2015-01-01

NEXAFS spectroscopy was used to investigate the temperature dependence of thermally active ethylene-vinyl acetate | multiwall carbon nanotube (EVA|MWCNT) films. The data shows systematic variations of intensities with increasing temperature. Molecular orbital assignment of interplaying intensities identified the 1s → π*C=C and 1s → π*C=O transitions as the main actors during temperature variation. Furthermore, enhanced near-edge interplay was observed in prestrained composites. Because macroscopic observations confirmed enhanced thermal-mechanical actuation in prestrained composites, our findings suggest that the interplay of C=C and C=O π orbitals may be instrumental to actuation. PMID:24803975

Electrical conductivity structure of the mantle derived from inversion of geomagnetic observatory data: implications for lateral variations in temperature, composition and water content.

NASA Astrophysics Data System (ADS)

Munch, Federico; Grayver, Alexander; Khan, Amir; Kuvshinov, Alexey

2017-04-01

As most of Earth's interior remains geochemically unsampled, geophysical techniques based on seismology, geodesy, gravimetry, and electromagnetic studies play prominent roles because of their ability to sense structure at depth. Although seismic tomography maps show a variety of structures, separating thermal and compositional contributions from seismic velocities alone still remains a challenging task. Alternatively, as electrical conductivity is sensitive to temperature, chemical composition, oxygen fugacity, water content, and the presence of melt, it can serve for determining chemistry, mineralogy, and physical structure of the deep mantle. In this work we estimate and invert local C-responses (period range 3-100 days) for a number of worldwide geomagnetic observatories to map lateral variations of electrical conductivity in Earth's mantle (400-1600 km depth). The obtained conductivity profiles are interpreted in terms of basalt fraction in a basalt-harzburgite mixture, temperature structure, and water content variations. Interpretation is based on a self-consistent thermodynamic calculation of mineral phase equilibria, electrical conductivity databases, and probabilistic inverse methods.

Regional variations in the diversity and predicted metabolic potential of benthic prokaryotes in coastal northern Zhejiang, East China Sea

PubMed Central

Wang, Kai; Ye, Xiansen; Zhang, Huajun; Chen, Heping; Zhang, Demin; Liu, Lian

2016-01-01

Knowledge about the drivers of benthic prokaryotic diversity and metabolic potential in interconnected coastal sediments at regional scales is limited. We collected surface sediments across six zones covering ~200 km in coastal northern Zhejiang, East China Sea and combined 16 S rRNA gene sequencing, community-level metabolic prediction, and sediment physicochemical measurements to investigate variations in prokaryotic diversity and metabolic gene composition with geographic distance and under local environmental conditions. Geographic distance was the most influential factor in prokaryotic β-diversity compared with major environmental drivers, including temperature, sediment texture, acid-volatile sulfide, and water depth, but a large unexplained variation in community composition suggested the potential effects of unmeasured abiotic/biotic factors and stochastic processes. Moreover, prokaryotic assemblages showed a biogeographic provincialism across the zones. The predicted metabolic gene composition similarly shifted as taxonomic composition did. Acid-volatile sulfide was strongly correlated with variation in metabolic gene composition. The enrichments in the relative abundance of sulfate-reducing bacteria and genes relevant with dissimilatory sulfate reduction were observed and predicted, respectively, in the Yushan area. These results provide insights into the relative importance of geographic distance and environmental condition in driving benthic prokaryotic diversity in coastal areas and predict specific biogeochemically-relevant genes for future studies. PMID:27917954

Temporal variation in isotopic composition and diet of Weddell seals in the western Ross Sea

NASA Astrophysics Data System (ADS)

Goetz, Kimberly T.; Burns, Jennifer M.; Hückstӓdt, Luis A.; Shero, Michelle R.; Costa, Daniel P.

2017-06-01

Weddell seals (Leptonychotes weddellii) are important predators in the Antarctic marine ecosystem, yet little is known about their diet. Previous studies have used scat and stomach content analyses to examine Weddell seal diet, however, these methods are biased towards prey with indigestible hard parts. To provide a more complete picture of their diet, we analyzed the stable isotope composition (δ13C and δ15N values) of red blood cells (RBC, n=96, representing a time scale of weeks to months) and vibrissae (n=45, representing months to a year) collected over a three year period (2010-2012). Our objectives were to (1) examine isotopic variation in relation to Weddell seal mass, sex, season, location, percent lipid, and age, and (2) quantify the contribution of prey items to overall diet. Body mass was a significant predictor of δ13C and δ15N values for both tissues, though the strength and direction of the relationship varied by year. The prey group consisting of Pleurogramma antarcticum and Trematomus newnesi was found to be an important dietary component, but its proportional contribution to Weddell seal diet varied with the timeframe represented by each tissue type [median RBC (range): 59.2% (40.2-8 1.1%); median mean vibrissae (range): 69.3% (43.9-89.6%)]. Results from mixing models ran for each seal indicate individual variation in diet. Overall, this study presents novel information on the isotopic variation and diet of Weddell seals over two time scales and provides insight into the feeding ecology of an important Antarctic predator.

A Variational Inverse Model Study of Amazonian Methane Emissions including Observations from the AMAZONICA campaign

NASA Astrophysics Data System (ADS)

Wilson, C. J.; Gloor, M.; Chipperfield, M.; Miller, J. B.; Gatti, L.

2013-12-01

Methane (CH4) is a greenhouse gas which is emitted from a range of anthropogenic and natural sources, and since the industrial revolution its mean atmospheric concentration has climbed dramatically, reaching values unprecedented in at least the past 650,000 years. CH4 produces a relatively high radiative forcing effect upon the Earth's climate, and its atmospheric lifetime of approximately 10 years makes it a more appealing target for the mitigation of climate change over short timescales than long-lived greenhouse gases such as carbon dioxide. However, the spatial and temporal variation of CH4 emissions are still not well understood, though in recent years a number of top-down and bottom-up studies have attempted to construct improved emission budgets. Some top-down studies may suffer from poor observational coverage in tropical regions, however, especially in the planetary boundary layer, where the atmosphere is highly sensitive to emissions. For example, although satellite observations often take a large volume of measurements in tropical regions, these retrievals are not usually sensitive to concentrations at the planet's surface. Methane emissions from Amazon region, in particular, are often poorly constrained. Since emissions form this region, coming mainly from wetland and biomass burning sources, are thought to be relatively high, additional observations in this region would greatly help to constrain the geographical distribution of the global CH4 emission budget. In order to provide such measurements, the AMAZONICA project began to take regular flask measurements of CH4 and other trace gases from aircraft over four Amazonian sites from the year 2010 onwards. We first present a forward modelling study of these observations of Amazonian methane for the year 2010 using the TOMCAT Chemical Transport Model. The model is used to attribute variations at each site to a source type and region, and also to assess the ability of our current CH4 flux estimates to

Metabolic Model-Based Integration of Microbiome Taxonomic and Metabolomic Profiles Elucidates Mechanistic Links between Ecological and Metabolic Variation.

PubMed

Noecker, Cecilia; Eng, Alexander; Srinivasan, Sujatha; Theriot, Casey M; Young, Vincent B; Jansson, Janet K; Fredricks, David N; Borenstein, Elhanan

2016-01-01

Multiple molecular assays now enable high-throughput profiling of the ecology, metabolic capacity, and activity of the human microbiome. However, to date, analyses of such multi-omic data typically focus on statistical associations, often ignoring extensive prior knowledge of the mechanisms linking these various facets of the microbiome. Here, we introduce a comprehensive framework to systematically link variation in metabolomic data with community composition by utilizing taxonomic, genomic, and metabolic information. Specifically, we integrate available and inferred genomic data, metabolic network modeling, and a method for predicting community-wide metabolite turnover to estimate the biosynthetic and degradation potential of a given community. Our framework then compares variation in predicted metabolic potential with variation in measured metabolites' abundances to evaluate whether community composition can explain observed shifts in the community metabolome, and to identify key taxa and genes contributing to the shifts. Focusing on two independent vaginal microbiome data sets, each pairing 16S community profiling with large-scale metabolomics, we demonstrate that our framework successfully recapitulates observed variation in 37% of metabolites. Well-predicted metabolite variation tends to result from disease-associated metabolism. We further identify several disease-enriched species that contribute significantly to these predictions. Interestingly, our analysis also detects metabolites for which the predicted variation negatively correlates with the measured variation, suggesting environmental control points of community metabolism. Applying this framework to gut microbiome data sets reveals similar trends, including prediction of bile acid metabolite shifts. This framework is an important first step toward a system-level multi-omic integration and an improved mechanistic understanding of the microbiome activity and dynamics in health and disease. Studies

Metabolic Model-Based Integration of Microbiome Taxonomic and Metabolomic Profiles Elucidates Mechanistic Links between Ecological and Metabolic Variation

PubMed Central

Noecker, Cecilia; Eng, Alexander; Srinivasan, Sujatha; Theriot, Casey M.; Young, Vincent B.; Jansson, Janet K.; Fredricks, David N.

2016-01-01

ABSTRACT Multiple molecular assays now enable high-throughput profiling of the ecology, metabolic capacity, and activity of the human microbiome. However, to date, analyses of such multi-omic data typically focus on statistical associations, often ignoring extensive prior knowledge of the mechanisms linking these various facets of the microbiome. Here, we introduce a comprehensive framework to systematically link variation in metabolomic data with community composition by utilizing taxonomic, genomic, and metabolic information. Specifically, we integrate available and inferred genomic data, metabolic network modeling, and a method for predicting community-wide metabolite turnover to estimate the biosynthetic and degradation potential of a given community. Our framework then compares variation in predicted metabolic potential with variation in measured metabolites’ abundances to evaluate whether community composition can explain observed shifts in the community metabolome, and to identify key taxa and genes contributing to the shifts. Focusing on two independent vaginal microbiome data sets, each pairing 16S community profiling with large-scale metabolomics, we demonstrate that our framework successfully recapitulates observed variation in 37% of metabolites. Well-predicted metabolite variation tends to result from disease-associated metabolism. We further identify several disease-enriched species that contribute significantly to these predictions. Interestingly, our analysis also detects metabolites for which the predicted variation negatively correlates with the measured variation, suggesting environmental control points of community metabolism. Applying this framework to gut microbiome data sets reveals similar trends, including prediction of bile acid metabolite shifts. This framework is an important first step toward a system-level multi-omic integration and an improved mechanistic understanding of the microbiome activity and dynamics in health and disease

Global characteristics in the diurnal variations of the thermospheric temperature and composition

NASA Technical Reports Server (NTRS)

Mayr, H. G.; Hedin, A. E.; Reber, C. A.; Carignan, G. R.

1973-01-01

Global characteristics in the diurnal components of OGO-6 neutral mass spectrometer measurements near 450 km are discussed qualitatively as well as quantitatively on the basis of a theoretical model. Observations and conclusion are summarized: (1) During equinox the temperature maximum occurs after 1600 LT at the equator and shifts toward 1500 LT at the poles, while the oxygen concentration at 450 km peaks about one hour earlier. (2) There is general agreement between the magnitudes and phases of the diurnal, semidiurnal and terdiuranal temperature components at 450 km from theory as well as OGO-6 and radar backscatter measurements. (3) The maximum in the diurnal variation of He is observed near 1030 LT consistent with theoretical results which further emphasize the importance of dynamics and diffusion. (4) During solstice conditions the diurnal temperature maximum shifts toward later local times, in substantial agreement with radar temperature measurements. (5) the temperature-oxygen density phase difference at 450 km is observed to decrease with latitude from the winter toward the summer hemisphere, where oxygen may even peak after the temperature at high latitudes.

Classifying Measures of Biological Variation

PubMed Central

Gregorius, Hans-Rolf; Gillet, Elizabeth M.

2015-01-01

Biological variation is commonly measured at two basic levels: variation within individual communities, and the distribution of variation over communities or within a metacommunity. We develop a classification for the measurement of biological variation on both levels: Within communities into the categories of dispersion and diversity, and within metacommunities into the categories of compositional differentiation and partitioning of variation. There are essentially two approaches to characterizing the distribution of trait variation over communities in that individuals with the same trait state or type tend to occur in the same community (describes differentiation tendencies), and individuals with different types tend to occur in different communities (describes apportionment tendencies). Both approaches can be viewed from the dual perspectives of trait variation distributed over communities (CT perspective) and community membership distributed over trait states (TC perspective). This classification covers most of the relevant descriptors (qualified measures) of biological variation, as is demonstrated with the help of major families of descriptors. Moreover, the classification is shown to open ways to develop new descriptors that meet current needs. Yet the classification also reveals the misclassification of some prominent and widely applied descriptors: Dispersion is often misclassified as diversity, particularly in cases where dispersion descriptor allow for the computation of effective numbers; the descriptor GST of population genetics is commonly misclassified as compositional differentiation and confused with partitioning-oriented differentiation, whereas it actually measures partitioning-oriented apportionment; descriptors of β-diversity are ambiguous about the differentiation effects they are supposed to represent and therefore require conceptual reconsideration. PMID:25807558

Satellite observed impacts of wildfires on regional atmosphere composition and shortwave radiative forcing: multiple cases study

NASA Astrophysics Data System (ADS)

Fu, Y.; Li, R.; Huang, J.; Bergeron, Y.; Fu, Y.

2017-12-01

Emissions of aerosols and trace gases from wildfires and the direct shortwave radiative forcing were studied using multi-satellite/sensor observations from Aqua Moderate-Resolution Imaging Spectroradiometer (MODIS), Aqua Atmospheric Infrared Sounder (AIRS), Aura Ozone Monitoring Instrument (OMI), and Aqua Cloud's and the Earth's Radiant Energy System (CERES). The selected cases occurred in Northeast of China (NEC), Siberia of Russia, California of America have dominant fuel types of cropland, mixed forest and needleleaf forest, respectively. The Fire radiative power (FRP) based emission coefficients (Ce) of aerosol, NOx (NO2+NO), formaldehyde (HCHO), and carbon monoxide (CO) showed significant differences from case to case. 1) the FRP of the cropland case in NEC is strongest, however, the Ce of aerosol is the lowest (20.51 ± 2.55 g MJ-1). The highest Ce of aerosol is 71.34 ± 13.24 g MJ-1 in the needleleaf fire case in California. 2) For NOx, the highest Ce existed in the cropland case in NEC (2.76 ± 0.25 g MJ-1), which is more than three times of those in the forest fires in Siberia and California. 3) The Ce of CO is 70.21±10.97 and 88.38±46.16 g MJ-1 in the forest fires in Western Siberia and California, which are about four times of that in cropland fire. 4) The variation of Ce of HCHO are relatively small among cases. Strong spatial correlations are found among aerosol optical depth (AOD), NOx, HCHO, and CO. The ratios of NOx to AOD, HCHO, and CO in the cropland case in NEC show much higher values than those in other cases. Although huge differences of emissions and composition ratios exist among cases, the direct shortwave (SW) radiative forcing efficiency (SWARFE) of smoke at the top of the atmosphere (TOA) are in good agreement, with the shortwave radiative forcing efficiencies values of 20.09 to 22.93 per unit AOD. Results in this study reveal noteworthy variations of the FRP-based emissions coefficient and relative chemical composition in the smoke

Only 7% of the variation in feed efficiency in veal calves can be predicted from variation in feeding motivation, digestion, metabolism, immunology, and behavioral traits in early life.

PubMed

Gilbert, M S; van den Borne, J J G C; van Reenen, C G; Gerrits, W J J

2017-10-01

High interindividual variation in growth performance is commonly observed in veal calf production and appears to depend on milk replacer (MR) composition. Our first objective was to examine whether variation in growth performance in healthy veal calves can be predicted from early life characterization of these calves. Our second objective was to determine whether these predictions differ between calves that are fed a high- or low-lactose MR in later life. A total of 180 male Holstein-Friesian calves arrived at the facilities at 17 ± 3.4 d of age, and blood samples were collected before the first feeding. Subsequently, calves were characterized in the following 9 wk (period 1) using targeted challenges related to traits within each of 5 categories: feeding motivation, digestion, postabsorptive metabolism, behavior and stress, and immunology. In period 2 (wk 10-26), 130 calves were equally divided over 2 MR treatments: a control MR that contained lactose as the only carbohydrate source and a low-lactose MR in which 51% of the lactose was isocalorically replaced by glucose, fructose, and glycerol (2:1:2 ratio). Relations between early life characteristics and growth performance in later life were assessed in 117 clinically healthy calves. Average daily gain (ADG) in period 2 tended to be greater for control calves (1,292 ± 111 g/d) than for calves receiving the low-lactose MR (1,267 ± 103 g/d). Observations in period 1 were clustered per category using principal component analysis, and the resulting principal components were used to predict performance in period 2 using multiple regression procedures. Variation in observations in period 1 predicted 17% of variation in ADG in period 2. However, this was mainly related to variation in solid feed refusals. When ADG was adjusted to equal solid feed intake, only 7% of the variation in standardized ADG in period 2, in fact reflecting feed efficiency, could be explained by early life measurements. This indicates that >90

Southern Greenland water vapour isotopic composition at the crossroads of Atlantic and Arctic moisture

NASA Astrophysics Data System (ADS)

Bonne, J. L.; Steen-Larsen, H. C.; Risi, C. M.; Werner, M.; Sodemann, H.; Lacour, J. L.; Fettweis, X.; Cesana, G.; Delmotte, M.; Cattani, O.; Clerbaux, C.; Sveinbjörnsdottir, A. E.; Masson-Delmotte, V.

2014-12-01

Since September 2011, a continuous water vapour isotopic composition monitoring instrument has been remotely operated in Ivittuut (61.21°N, 48.17°W), southern Greenland. Meteorological parameters are monitored and precipitation has been sampled and analysed for isotopic composition, suggesting equilibrium between surface vapour and precipitation. The data depict small summer diurnal variations. δ18O and deuterium excess (d-excess) are generally anti-correlated and show important seasonal variations (with respective amplitudes of 10 and 20 ‰), and large synoptic variations associated to low-pressure systems (typically +5‰ on δ18O and -15‰ on d-excess). The moisture sources, estimated based on Lagrangian back-trajectories, are primarily influenced by the western North Atlantic, and north-eastern American continent. Notable are important seasonal and synoptic shifts of the moisture sources, and sporadic influences of the Arctic or the eastern North Atlantic. Moisture sources variations can be related to changes in water vapour isotopic composition, and the isotopic fingerprints can be attributed to the areas of moisture origins. Isotopic enabled AGCMs nudged to meteorology (LMDZiso, ECHAM5-wiso), despite biases, correctly capture the δ18O changes, but underestimate the d-excess changes. They allow to identify a high correlation between the southern Greenland d-excess and the simulated relative humidity and d-excess in the moisture source region south of Greenland. An extreme high temperature event in July 2012 affecting all Greenland, similar to ice sheet melt events during the medieval periods and one event in 1889 documented by Greenland ice core records, has been analysed regarding water vapour isotopic composition, using remote sensing (IASI) and in situ observations from Bermuda to northern Greenland (NEEM station). Our southern Greenland observations allow to track the water vapour evolution during this event along the moisture transport path

Correlations Between Variations in Solar EUV and Soft X-Ray Irradiance and Photoelectron Energy Spectra Observed on Mars and Earth

NASA Technical Reports Server (NTRS)

Peterson, W. K.; Brain, D. A.; Mitchell, D. L.; Bailey, S. M.; Chamberlin, P. C.

2013-01-01

Solar extreme ultraviolet (EUV; 10-120 nm) and soft X-ray (XUV; 0-10 nm) radiation are major heat sources for the Mars thermosphere as well as the primary source of ionization that creates the ionosphere. In investigations of Mars thermospheric chemistry and dynamics, solar irradiance models are used to account for variations in this radiation. Because of limited proxies, irradiance models do a poor job of tracking the significant variations in irradiance intensity in the EUV and XUV ranges over solar rotation time scales when the Mars-Sun-Earth angle is large. Recent results from Earth observations show that variations in photoelectron energy spectra are useful monitors of EUV and XUV irradiance variability. Here we investigate photoelectron energy spectra observed by the Mars Global Surveyor (MGS) Electron Reflectometer (ER) and the FAST satellite during the interval in 2005 when Earth, Mars, and the Sun were aligned. The Earth photoelectron data in selected bands correlate well with calculations based on 1 nm resolution observations above 27 nm supplemented by broadband observations and a solar model in the 0-27 nm range. At Mars, we find that instrumental and orbital limitations to the identifications of photoelectron energy spectra in MGS/ER data preclude their use as a monitor of solar EUV and XUV variability. However, observations with higher temporal and energy resolution obtained at lower altitudes on Mars might allow the separation of the solar wind and ionospheric components of electron energy spectra so that they could be used as reliable monitors of variations in solar EUV and XUV irradiance than the time shifted, Earth-based, F(10.7) index currently used.

Correlations between variations in solar EUV and soft X-ray irradiance and photoelectron energy spectra observed on Mars and Earth

NASA Astrophysics Data System (ADS)

Peterson, W. K.; Brain, D. A.; Mitchell, D. L.; Bailey, S. M.; Chamberlin, P. C.

2013-11-01

extreme ultraviolet (EUV; 10-120 nm) and soft X-ray (XUV; 0-10 nm) radiation are major heat sources for the Mars thermosphere as well as the primary source of ionization that creates the ionosphere. In investigations of Mars thermospheric chemistry and dynamics, solar irradiance models are used to account for variations in this radiation. Because of limited proxies, irradiance models do a poor job of tracking the significant variations in irradiance intensity in the EUV and XUV ranges over solar rotation time scales when the Mars-Sun-Earth angle is large. Recent results from Earth observations show that variations in photoelectron energy spectra are useful monitors of EUV and XUV irradiance variability. Here we investigate photoelectron energy spectra observed by the Mars Global Surveyor (MGS) Electron Reflectometer (ER) and the FAST satellite during the interval in 2005 when Earth, Mars, and the Sun were aligned. The Earth photoelectron data in selected bands correlate well with calculations based on 1 nm resolution observations above 27 nm supplemented by broadband observations and a solar model in the 0-27 nm range. At Mars, we find that instrumental and orbital limitations to the identifications of photoelectron energy spectra in MGS/ER data preclude their use as a monitor of solar EUV and XUV variability. However, observations with higher temporal and energy resolution obtained at lower altitudes on Mars might allow the separation of the solar wind and ionospheric components of electron energy spectra so that they could be used as reliable monitors of variations in solar EUV and XUV irradiance than the time shifted, Earth-based, F10.7 index currently used.

Essential oil variation in wild populations of Artemisia saharae (Asteraceae) from Tunisia: chemical composition, antibacterial and antioxidant properties.

PubMed

Zouari, Sami; Ayadi, Imen; Fakhfakh, Nahed; Jdir, Hamida; Aloui, Latifa; Kossentini, Mohamed; Rebai, Ahmed; Zouari, Nacim

2014-12-01

Artemisia saharae Pomel is a new taxon of Artemisia herba-alba Asso (Asteraceae) which is endemic to Tunisia and Algeria. This shrub, commonly known as white wormwood or desert wormwood, is largely used in folk medicine and as a culinary herb. The bulks aromatic plants come from wild populations whose essential oils compositions as well as their biological properties are severely affected by several factors such as geographic conditions. Therefore, the aim of the present work is to provide more information about the influence of altitude variation on the essential oil composition, antimicrobial and antioxidant properties of Artemisia saharae growing wild in the same geographical area. Essential oils were extracted by hydrodistillation of leaves and flowers of the plant collected from seven different altitudes of the Baten Zamour region (southwest of Tunisia). The highest essential oil yields (2.70-2.80%) were obtained for populations of high altitudes. Seventy-five compounds, representing 92.78 to 96.95% of the total essential oils, were separated and identified. Essential oils were characterized by very high percentage of oxygenated monoterpenes (52.1-72.6%) which constituted the predominant class. From the analyzed populations, the major compounds (>7%) were α-thujone, β-thujone, chrysanthenone, camphor, chrysanthenyl acetate, and sabinyl acetate. Sabinyl acetate which was detected in some populations at relatively high percentages (7.7-10.8%) seems to be characteristic to Southern Tunisian A. saharae. The studied essential oil showed a chemical diversity depending on the population altitude as revealed by linear discriminant and cluster analyses. Three population groups associated with altitudinal levels were distinguished. It is worthy to note that the most discriminating compounds of chemical groups were the minor ones. Despite the high variation of essential oil compositions, the high altitude population did not affect severely the antibacterial activity

Scale-dependent variation in nitrogen cycling and soil fungal communities along gradients of forest composition and age in regenerating tropical dry forests.

PubMed

Waring, Bonnie G; Adams, Rachel; Branco, Sara; Powers, Jennifer S

2016-01-01

Rates of ecosystem nitrogen (N) cycling may be mediated by the presence of ectomycorrhizal fungi, which compete directly with free-living microbes for N. In the regenerating tropical dry forests of Central America, the distribution of ectomycorrhizal trees is affected by succession and soil parent material, both of which may exert independent influence over soil N fluxes. In order to quantify these interacting controls, we used a scale-explicit sampling strategy to examine soil N cycling at scales ranging from the microsite to ecosystem level. We measured fungal community composition, total and inorganic N pools, gross proteolytic rate, net N mineralization and microbial extracellular enzyme activity at multiple locations within 18 permanent plots that span dramatic gradients of soil N concentration, stand age and forest composition. The ratio of inorganic to organic N cycling was correlated with variation in fungal community structure, consistent with a strong influence of ectomycorrhiza on ecosystem-scale N cycling. However, on average, > 61% of the variation in soil biogeochemistry occurred within plots, and the effects of forest composition were mediated by this local-scale heterogeneity in total soil N concentrations. These cross-scale interactions demonstrate the importance of a spatially explicit approach towards an understanding of controls on element cycling. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

Mercury's Seasonal Sodium Exosphere: MESSENGER Orbital Observations

NASA Technical Reports Server (NTRS)

Cassidy, Timothy A.; Merkel, Aimee W.; Burger, Matthew H.; Sarantos, Menelaos; Killen, Rosemary M.; McClintock, William E.; Vervack, Ronald J., Jr.

2014-01-01

The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) Ultraviolet and Visible Spectrometer (UVVS) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft now orbiting Mercury provides the first close-up look at the planet's sodium exosphere. UVVS has observed the exosphere from orbit almost daily for over 10 Mercury years. In this paper we describe and analyze a subset of these data: altitude profiles taken above the low-latitude dayside and south pole. The observations show spatial and temporal variation but there is little or no year-to-year variation; we do not see the episodic variability reported by ground-based observers. We used these altitude profiles to make estimates of sodium density and temperature. The bulk of the exosphere is about 1200 K, much warmer than Mercury's surface. This value is consistent with some ground-based measurements and suggests that photon-stimulated desorption is the primary ejection process. We also observe a tenuous energetic component but do not see evidence of the predicted thermalized (or partially thermalized) sodium near Mercury's surface temperature. Overall we do not see the variable mixture of temperatures predicted by most Monte Carlo models of the exosphere.

Mind the cell: Seasonal variation in telomere length mirrors changes in leucocyte profile.

PubMed

Beaulieu, Michaël; Benoit, Laure; Abaga, Steven; Kappeler, Peter M; Charpentier, Marie J E

2017-10-01

Leucocytes are typically considered as a whole in studies examining telomere dynamics in mammals. Such an approach may be precarious, as leucocytes represent the only nucleated blood cells in mammals, their composition varies temporally, and telomere length differs between leucocyte types. To highlight this limitation, we examined here whether seasonal variation in leucocyte composition was related to variation in telomere length in free-ranging mandrills (Mandrilllus sphinx). We found that the leucocyte profile of mandrills varied seasonally, with lower lymphocyte proportion being observed during the long dry season presumably because of the combined effects of high nematode infection and stress at that time of the year. Interestingly, this low lymphocyte proportion during the long dry season was associated with shorter telomeres. Accordingly, based on longitudinal data, we found that seasonal changes in lymphocyte proportion were reflected by corresponding seasonal variation in telomere length. Overall, these results suggest that variation in lymphocyte proportion in blood can significantly affect telomere measurements in mammals. However, lymphocyte proportion did not entirely explain variation in telomere length. For instance, a lower lymphocyte proportion with age could not fully explain shorter telomeres in older individuals. Overall, our results show that telomere length and leucocyte profile are strongly although imperfectly intertwined, which may obscure the relationship between telomere dynamics and ageing processes in mammals. © 2017 John Wiley & Sons Ltd.

Geomorphic determinants of species composition of alpine tundra, Glacier National Park, U.S.A.

USGS Publications Warehouse

George P. Malanson,; Bengtson, Lindsey E.; Fagre, Daniel B.

2012-01-01

Because the distribution of alpine tundra is associated with spatially limited cold climates, global warming may threaten its local extent or existence. This notion has been challenged, however, based on observations of the diversity of alpine tundra in small areas primarily due to topographic variation. The importance of diversity in temperature or moisture conditions caused by topographic variation is an open question, and we extend this to geomorphology more generally. The extent to which geomorphic variation per se, based on relatively easily assessed indicators, can account for the variation in alpine tundra community composition is analyzed versus the inclusion of broad indicators of regional climate variation. Visual assessments of topography are quantified and reduced using principal components analysis (PCA). Observations of species cover are reduced using detrended correspondence analysis (DCA). A “best subsets” regression approach using the Akaike Information Criterion for selection of variables is compared to a simple stepwise regression with DCA scores as the dependent variable and scores on significant PCA axes plus more direct measures of topography as independent variables. Models with geographic coordinates (representing regional climate gradients) excluded explain almost as much variation in community composition as models with them included, although they are important contributors to the latter. The geomorphic variables in the model are those associated with local moisture differences such as snowbeds. The potential local variability of alpine tundra can be a buffer against climate change, but change in precipitation may be as important as change in temperature.

Quantifying the Impact of Land Cover Composition on Intra-Urban Air Temperature Variations at a Mid-Latitude City

PubMed Central

Yan, Hai; Fan, Shuxin; Guo, Chenxiao; Hu, Jie; Dong, Li

2014-01-01

The effects of land cover on urban-rural and intra-urban temperature differences have been extensively documented. However, few studies have quantitatively related air temperature to land cover composition at a local scale which may be useful to guide landscape planning and design. In this study, the quantitative relationships between air temperature and land cover composition at a neighborhood scale in Beijing were investigated through a field measurement campaign and statistical analysis. The results showed that the air temperature had a significant positive correlation with the coverage of man-made surfaces, but the degree of correlation varied among different times and seasons. The different land cover types had different effects on air temperature, and also had very different spatial extent dependence: with increasing buffer zone size (from 20 to 300 m in radius), the correlation coefficient of different land cover types varied differently, and their relative impacts also varied among different times and seasons. At noon in summer, ∼37% of the variations in temperature were explained by the percentage tree cover, while ∼87% of the variations in temperature were explained by the percentage of building area and the percentage tree cover on summer night. The results emphasize the key role of tree cover in attenuating urban air temperature during daytime and nighttime in summer, further highlighting that increasing vegetation cover could be one effective way to ameliorate the urban thermal environment. PMID:25010134

Sulphur and oxygen isotopic composition of sulphates in springs feeding the Wieprz river and other springs of Lublin Upland and Roztocze.

PubMed

Trembaczowski, A; Swieca, A

2002-12-01

Springs on Roztocze and Lublin Upland have been studied. Isotopic data are compared with data of chemical analyses. The results of studies allow us to distinguish five types of groundwaters. The differentiation is based upon different lithology; opokas, gaizes, sandy-silty-clay deposits, sands with shell sandstones, marly opokas, marly limestones and 'soft limestones of chalk type. A correlation can be observed between delta34S and the concentration of Ca or Mg ions also a correlation between HCO3- ion concentration and delta18O in sulphates. Probably these correlations are the result of some simultaneous processes, which occur in groundwater. The seasonal variations of the isotopic composition and sulphate concentration were observed in four springs feeding the upper Wieprz. The variations were simultaneous and often similar in these springs. Probably, these variations are caused by the admixture of sulphates coming from shallow water layers (or leached from soil); however the variations of the groundwater level may also change chemical and isotopic composition in groundwater.

Mind the gut: genomic insights to population divergence and gut microbial composition of two marine keystone species.

PubMed

Fietz, Katharina; Rye Hintze, Christian Olaf; Skovrind, Mikkel; Kjærgaard Nielsen, Tue; Limborg, Morten T; Krag, Marcus A; Palsbøll, Per J; Hestbjerg Hansen, Lars; Rask Møller, Peter; Gilbert, M Thomas P

2018-05-02

Deciphering the mechanisms governing population genetic divergence and local adaptation across heterogeneous environments is a central theme in marine ecology and conservation. While population divergence and ecological adaptive potential are classically viewed at the genetic level, it has recently been argued that their microbiomes may also contribute to population genetic divergence. We explored whether this might be plausible along the well-described environmental gradient of the Baltic Sea in two species of sand lance (Ammodytes tobianus and Hyperoplus lanceolatus). Specifically, we assessed both their population genetic and gut microbial composition variation and investigated not only which environmental parameters correlate with the observed variation, but whether host genome also correlates with microbiome variation. We found a clear genetic structure separating the high-salinity North Sea from the low-salinity Baltic Sea sand lances. The observed genetic divergence was not simply a function of isolation by distance, but correlated with environmental parameters, such as salinity, sea surface temperature, and, in the case of A. tobianus, possibly water microbiota. Furthermore, we detected two distinct genetic groups in Baltic A. tobianus that might represent sympatric spawning types. Investigation of possible drivers of gut microbiome composition variation revealed that host species identity was significantly correlated with the microbial community composition of the gut. A potential influence of host genetic factors on gut microbiome composition was further confirmed by the results of a constrained analysis of principal coordinates. The host genetic component was among the parameters that best explain observed variation in gut microbiome composition. Our findings have relevance for the population structure of two commercial species but also provide insights into potentially relevant genomic and microbial factors with regards to sand lance adaptation across

Chaotic behaviour of the short-term variations in ozone column observed in Arctic

NASA Astrophysics Data System (ADS)

Petkov, Boyan H.; Vitale, Vito; Mazzola, Mauro; Lanconelli, Christian; Lupi, Angelo

2015-09-01

The diurnal variations observed in the ozone column at Ny-Ålesund, Svalbard during different periods of 2009, 2010 and 2011 have been examined to test the hypothesis that they could be a result of a chaotic process. It was found that each of the attractors, reconstructed by applying the time delay technique and corresponding to any of the three time series can be embedded by 6-dimensional space. Recurrence plots, depicted to characterise the attractor features revealed structures typical for a chaotic system. In addition, the two positive Lyapunov exponents found for the three attractors, the fractal Hausdorff dimension presented by the Kaplan-Yorke estimator and the feasibility to predict the short-term ozone column variations within 10-20 h, knowing the past behaviour make the assumption about their chaotic character more realistic. The similarities of the estimated parameters in all three cases allow us to hypothesise that the three time series under study likely present one-dimensional projections of the same chaotic system taken at different time intervals.

Seasonal and Interannual Variations of Ice Sheet Surface Elevation at the Summit of Greenland: Observed and Modeled

NASA Technical Reports Server (NTRS)

Zwally, H. Jay; Jun, Li; Koblinsky, Chester J. (Technical Monitor)

2001-01-01

Observed seasonal and interannual variations in the surface elevation over the summit of the Greenland ice sheet are modeled using a new temperature-dependent formulation of firn-densification and observed accumulation variations. The observed elevation variations are derived from ERS (European Remote Sensing)-1 and ERS-2 radar altimeter data for the period between April 1992 and April 1999. A multivariate linear/sine function is fitted to an elevation time series constructed from elevation differences measured by radar altimetry at orbital crossovers. The amplitude of the seasonal elevation cycle is 0.25 m peak-to-peak, with a maximum in winter and a minimum in summer. Inter-annually, the elevation decreases to a minimum in 1995, followed by an increase to 1999, with an overall average increase of 4.2 cm a(exp -1) for 1992 to 1999. Our densification formulation uses an initial field-density profile, the AWS (automatic weather station) surface temperature record, and a temperature-dependent constitutive relation for the densification that is based on laboratory measurements of crystal growth rates. The rate constant and the activation energy commonly used in the Arrhenius-type constitutive relation for firn densification are also temperature dependent, giving a stronger temperature and seasonal amplitudes about 10 times greater than previous densification formulations. Summer temperatures are most important, because of the strong non-linear dependence on temperature. Much of firn densification and consequent surface lowering occurs within about three months of the summer season, followed by a surface build-up from snow accumulation until spring. Modeled interannual changes of the surface elevation, using the AWS measurements of surface temperature and accumulation and results of atmospheric modeling of precipitation variations, are in good agreement with the altimeter observations. In the model, the surface elevation decreases about 20 cm over the seven years due

Variations of GHGs from the lower-troposphere to the UT/LS revealed by two Japanese regular aircraft observation programs

NASA Astrophysics Data System (ADS)

Niwa, Yosuke; Machida, Toshinobu; Sawa, Yousuke; Tsuboi, Kazuhiro; Matsueda, Hidekazu; Imasu, Ryoichi

2014-05-01

A Japan-centered observation network consisting of two regular aircraft programs have revealed the greenhouse gases variations from the lower-troposphere to the upper-troposphere/lower-stratosphere (UT/LS) regions. In the Comprehensive Observation Network for Trace gases by Airliner (CONTRAIL) project, in-situ continuous measurement equipment (CME) onboard commercial passenger aircraft world-widely observes CO2 profiles in vertical over tens of airports and in horizontal in the UT/LS regions. The CONTRAIL-CME has revealed three-dimensional structure of the global CO2 distribution and has exposed significant inter-hemispheric transport of CO2 through the upper-troposphere. In inverse modeling, the CME data have provided strong constraints on CO2 flux estimation especially for the Asian tropics. Automatic flask air sampling equipment (ASE) is also onboard the CONTRAIL aircraft and has been observing CO2 mixing ratios as well as those of methane, carbon monoxide, nitrous oxide and other trace species in the upper-troposphere between Japan and Australia. The observation period of the ASE has reached 20 years. In recent years, the ASE program has extended to the northern subarctic UT/LS region and has given an insight of transport mechanisms in the UT/LS by observing seasonal GHGs variations. In the other aircraft observation program by Japan Meteorological Agency, variations of GHGs have been observed by flask-sampling onboard a C-130H aircraft horizontally in the mid-troposphere over the western North Pacific as well as vertically over Minamitorishima-Island. The C-130H aircraft has persistently observed high mixing ratios of CH4 in the mid-troposphere, which seems to be originated from fossil fuel combustion throughout the year as well as from biogenic sources during summer in the Asian regions. Those above aircraft observation programs have a significant role for constraining GHGs flux estimates by filling the data gap of the existing surface measurement network

Compositional Variation in Apollo 16 Impact-Melt Breccias and Inferences for the Geology and Bombardment History of the Central Highlands of the Moon

NASA Technical Reports Server (NTRS)

Korotev, Randy L.

1994-01-01

feldspathic fragmental breccias from North Ray crater (group 2NR) is compositionally distinct from the melt lithology ofdimict breccias from the Cayley plains (group 2DB) in having higher concentrations of Sc, Cr, and heavy rare earth elements and lower concentrations of siderophile elements. The distinct siderophile-element signature (high absolute abundances, low Ir/Au ratio) suggest that the four groups ofmafic melt breccia are all somehow related. Ratios ofsome lithophile elements also suggest that they are more closely related to each other than then, are to melt breccias from other Apoll sites. However, none of the breccia compositions can be related to any of the others by any simple process of igneous fractionation or mixing involving common lunar materials. Thus, the origin of the four groups of mafic melt breccia is enigmatic. If they were produced in only one or two impacts, then a mechanism exists for generating regimes of impact-melt breccia in a single impact that are substantially different from each other in composition. For various reasons, including the problem of delivering large volumes of four different types of melt to the Apollo 16 site, it is unlikely that any of these breccias were produced in basin-forming impacts. If they were produced in as many as four crater-forming impacts, then the unusual siderophile-element signature is difficult to explain. Possible explanations are (1) the four groups of melt breccia all contain metal from a single, earlier impact, (2) they were each formed by related metal-rich meteoroids, or (3) some common postimpact process has resulted in metal of similar composition in each of four melt pools. Within a compositional group, most intrasample and intersample variation in lithophile element concentrations is caused by differences among samples in the proportion of a component of normative anorthosite or noritic anorthosite. In most cases, this compositional variation probably reflects variation in clast abundance. For

Anatomical variations of uncinate process observed in chronic sinusitis.

PubMed

Tuli, Isha Preet; Sengupta, Subhabrata; Munjal, Sudeep; Kesari, Santosh Prasad; Chakraborty, Suvamoy

2013-04-01

Chronic Sinusitis, an extremely persistent illness, is surgically best treated by Functional Endoscopic Sinus Surgery. The ostiomeatal complex is the main area targeted and within it uncinate process is the first anatomical structure encountered. The significance of anatomical variations concerning age and sex of uncinate process in chronic sinusitis were evaluated. A prospective study on 50 patients of chronic sinusitis (100 uncinate processes) was done. The results were tabulated and analyzed using Statistical Package for Social Science (SPSS) 16.0. Type I superior attachment of uncinate process (67 %) was the most common variety in all ages and both sexes and a statistically significant relationship between Type I superior attachment of uncinate process and sex was found (p < 0.05). The typical uncinate process was most common (70 %) followed by medial deviation of the uncinate (24 %). This difference in occurrence was significant with respect to both age and sex (p < 0.05). Anatomical variations of uncinate process are not responsible for causing chronic sinusitis. Mere presence of these variations of uncinate is not an indication for FESS.

Optimal Observations for Variational Data Assimilation

NASA Technical Reports Server (NTRS)

Koehl, Armin; Stammer, Detlef

2003-01-01

An important aspect of Ocean state estimation is the design of an observing system that allows the efficient study of climate aspects in the ocean. A solution of the design problem is presented here in terms of optimal observations that emerge as nondimensionalized singular vectors of the modified data resolution matrix. The actual computation is feasible only for scalar quantities in the limit of large observational errors. In the framework of a lo resolution North Atlantic primitive equation model it is demonstrated that such optimal observations when applied to determining the strength of the volume and heat transport across the Greenland-Scotland ridge, perform significantly better than traditional section data. On seasonal to inter-annual time-scales optimal observations are located primarily along the continental shelf and information about heat-transport, wind stress and stratification is being communicated via boundary waves and advective processes. On time-scales of about a month, sea surface height observations appear to be more efficient in reconstructing the cross-ridge heat transport than hydrographic observations. Optimal observations also provide a tool for understanding how the ocean state is effected by anomalies of integral quantities such as meridional heat transport.

Mercury's Seasonal Sodium Exosphere: MESSENGER Orbital Observations

NASA Technical Reports Server (NTRS)

Cassidy, Timothy A.; Merkel, Aimee W.; Burger, Matthew H.; Killen, Rosemary M.; McClintock, William E.; Vervack, Ronald J., Jr.; Sarantos, Menelaos

2014-01-01

The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) Ultraviolet and Visible Spectrometer (UVVS) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft now orbiting Mercury provides the first close-up look at the planet's sodium exosphere. UVVS has observed the exosphere from orbit almost daily for over 10 Mercury years. In this paper we describe and analyze a subset of these data: altitude profiles taken above the low-latitude dayside and south pole. The observations show spatial and temporal variations, but there are no obvious year-to-year variations in most of the observations. We do not see the episodic variability reported by some ground-based observers. We used these altitude profiles to make estimates of sodium density and temperature. The bulk of the exosphere, at about 1200 K, is much warmer than Mercury's surface. This value is consistent with some ground-based measurements and suggests that photon-stimulated desorption is the primary ejection process. We also observe a tenuous energetic component but do not see evidence of the predicted thermalized (or partially thermalized) sodium near Mercury's surface temperature. Overall we do not see the variable mixture of temperatures predicted by most Monte Carlo models of the exosphere.

Isotope variations of dissolved Zn in the Rio Grande watershed, USA: The role of adsorption on Zn isotope composition

NASA Astrophysics Data System (ADS)

Szynkiewicz, Anna; Borrok, David M.

2016-01-01

In order to better understand the factors influencing zinc (Zn) isotope composition in hydrological systems, we analyzed the δ66Zn of dissolved Zn in the streams and groundwater of the Upper and Middle Rio Grande watershed in Colorado and New Mexico, United States. The stream water samples have a wider variation of δ66Zn (-0.57 to + 0.41 ‰ relative to the JMC 3-0749-Lyon standard) than groundwater samples (-0.13 to + 0.12 ‰) and than samples from streams that are in close proximity to abandoned mining sites (+0.24 to + 0.40 ‰). Regional changes of bedrock geology, from primarily igneous rocks to primarily sedimentary rocks, have no resolvable effect on the δ66Zn of aqueous samples. Instead, an increase in water pH from 7.5 to 8.5 corresponds to a considerable decrease in the δ66Zn of dissolved Zn (R2 = - 0.37, p = 0.003, n = 22). Consequently, we link the observed Zn isotope variations to the process of adsorption of Zn onto suspended sediment and bedrock minerals (average Δ66Znadsorbed-dissolved = + 0.31 ‰). Our results are in good agreement with previous experimental and empirical studies suggesting that Zn adsorption leads to a residual dissolved pool enriched in light Zn isotopes. Given that anthropogenic Zn sources can also be responsible for lowering of δ66Zn, and may overlap with the pH/adsorption effect on δ66Zn, the latter needs to be carefully considered in future studies to differentiate between natural and anthropogenic factors influencing Zn isotopes in this and other aquatic systems.

Satellite Observations for Detecting and Tracking Changes in Atmospheric Composition

NASA Technical Reports Server (NTRS)

Neil, Doreen O.; Kondragunbta, Shobha; Osterman, Gregory; Pickering, Kenneth; Pinder, Robert W.; Prados, Ana I.; Szykman, James

2009-01-01

The satellite observations provide constraints on detailed atmospheric modeling, including emissions inventories, indications of transport, harmonized data over vast areas suitable for trends analysis, and a link between spatial scales ranging from local to global, and temporal scales from diurnal to interannual. 1 The National Oceanic and Atmospheric Administration's (NOAA) long-term commitments help provide these observations in cooperation with international meteorological organizations. NASA s long-term commitments will advance scientifically important observations as part of its Earth Science Program, and will assist the transition of the science measurements to applied analyses through the Applied Science Program. Both NASA and NOAA have begun to provide near realtime data and tools to visualize and analyze satellite data,2 while maintaining data quality, validation, and standards. Consequently, decision-makers can expect satellite data services to support air quality decision making now and in the future. The international scientific community's Integrated Global Atmosphere Chemistry Observation System Report3 outlined a plan for ground-based, airborne and satellite measurements and models to integrate the observations into a four-dimensional representation of the atmosphere (space and time) to support assessment and policy information needs. This plan is being carried out under the Global Earth Observation System of Systems (GEOSS). Demonstrations of such an integrated capability4 provide new understanding of the changing atmosphere and link policy decisions to benefits for society. In this article, we highlight the use of satellite data to constrain biomass burning emissions, to assess oxides of nitrogen (NO(x)) emission reductions, and to contribute to state implementation plans, as examples of the use of satellite observations for detecting and tracking changes in atmospheric composition.

The neodymium stable isotope composition of the silicate Earth and chondrites

NASA Astrophysics Data System (ADS)

McCoy-West, Alex J.; Millet, Marc-Alban; Burton, Kevin W.

2017-12-01

The non-chondritic neodymium (Nd) 142Nd/144Nd ratio of the silicate Earth potentially provides a key constraint on the accretion and early evolution of the Earth. Yet, it is debated whether this offset is due to the Earth being formed from material enriched in s-process Nd isotopes or results from an early differentiation process such as the segregation of a late sulfide matte during core formation, collisional erosion or a some combination of these processes. Neodymium stable isotopes are potentially sensitive to early sulfide segregation into Earth's core, a process that cannot be resolved using their radiogenic counterparts. This study presents the first comprehensive Nd stable isotope data for chondritic meteorites and terrestrial rocks. Stable Nd measurements were made using a double spike technique coupled with thermal ionisation mass spectrometry. All three of the major classes of chondritic meteorites, carbonaceous, enstatite and ordinary chondrites have broadly similar isotopic compositions allowing calculation of a chondritic mean of δ146/144Nd = -0.025 ± 0.025‰ (±2 s.d.; n = 39). Enstatite chondrites yield the most uniform stable isotope composition (Δ146/144Nd = 26 ppm), with considerably more variability observed within ordinary (Δ146/144Nd = 72 ppm) and carbonaceous meteorites (Δ146/144Nd = 143 ppm). Terrestrial weathering, nucleosynthetic variations and parent body thermal metamorphism appear to have little measurable effect on δ146/144Nd in chondrites. The small variations observed between ordinary chondrite groups most likely reflect inherited compositional differences between parent bodies, with the larger variations observed in carbonaceous chondrites being linked to varying modal proportions of calcium-aluminium rich inclusions. The terrestrial samples analysed here include rocks ranging from basaltic to rhyolitic in composition, MORB glasses and residual mantle lithologies. All of these terrestrial rocks possess a broadly similar Nd

Oxygen isotope variations at the margin of a CAI records circulation within the solar nebula.

PubMed

Simon, Justin I; Hutcheon, Ian D; Simon, Steven B; Matzel, Jennifer E P; Ramon, Erick C; Weber, Peter K; Grossman, Lawrence; DePaolo, Donald J

2011-03-04

Micrometer-scale analyses of a calcium-, aluminum-rich inclusion (CAI) and the characteristic mineral bands mantling the CAI reveal that the outer parts of this primitive object have a large range of oxygen isotope compositions. The variations are systematic; the relative abundance of (16)O first decreases toward the CAI margin, approaching a planetary-like isotopic composition, then shifts to extremely (16)O-rich compositions through the surrounding rim. The variability implies that CAIs probably formed from several oxygen reservoirs. The observations support early and short-lived fluctuations of the environment in which CAIs formed, either because of transport of the CAIs themselves to distinct regions of the solar nebula or because of varying gas composition near the proto-Sun.

Morphology and time variation of the Jovian Far UV aurora: Hubble Space Telescope observations

NASA Technical Reports Server (NTRS)

Gerard, Jean-Claude; Dols, Vincent; Paresce, Francesco; Prange, Renee

1993-01-01

High spatial resolution images of the north polar region of Jupiter have been obtained with the Faint Object Camera (FOC) on board the Hubble Space Telescope (HST). The first set of two images collected 87 min apart in February 1992 shows a bright (approximately or equal to 180 kR) emission superimposed on the background in rotation with the planet. Both Ly alpha images show common regions of enhanced emission but differences are also observed, possibly due to temporal variations. The second group of images obtained on June 23 and 26, 1992 isolates a spectral region near 153 nm dominated by the H2 Lyman bands and continuum. Both pictures exhibit a narrow arc structure fitting the L = 30 magnetotail field line footprint in the morning sector and a broader diffuse aurora in the afternoon. They show no indication of an evening twilight enhancement. Although the central meridian longitudes were similar, significant differences are seen in the two exposures, especially in the region of diffuse emission, and interpreted as signatures of temporal variations. The total power radiated in the H2 bands is approximately or equal to 2 x 10(exp 12) W, in agreement with previous UV spectrometer observations. The high local H2 emission rates (approximately 450 kR) imply a particle precipitation carrying an energy flux of about 5 x 10(exp -2) W/sq m.

Composition variations of low energy heavy ions during large solar energetic particle events

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ho, George C., E-mail: George.Ho@jhuapl.edu; Mason, Glenn M., E-mail: Glenn.Mason@jhuapl.edu

2016-03-25

The time-intensity profile of large solar energetic particle (SEP) event is well organized by solar longitude as observed at Earth orbit. This is mostly due to different magnetic connection to the shock that is associated with large SEP event propagates from the Sun to the heliosphere. Earlier studies have shown event averaged heavy ion abundance ratios can also vary as a function of solar longitude. It was found that the Fe/O ratio for high energy particle (>10 MeV/nucleon) is higher for those western magnetically well connected events compare to the eastern events as observed at L1 by the Advanced Composition Explorermore » (ACE) spacecraft. In this paper, we examined the low energy (∼1 MeV/nucleon) heavy ions in 110 isolated SEP events from 2009 to the end of 2014. In addition, the optical and radio signatures for all of our events are identified and when data are available we also located the associated coronal mass ejection (CME) data. Our survey shows a higher Fe/O ratio at events in the well-connected region, while there are no corrections between the event averaged elemental composition with the associated coronal mass ejection speed. This is inconsistent with the higher energy results, but inline with other recent low-energy measurements.« less

Age hardening of 6061/alumina-silica fiber composite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khangaonkar, P.R.; Shamsul, J.B.; Azmi, R.

1994-12-31

Continuous alumina-silica fiber (Altex of Sumitomo) which yields high performance composites with some aluminium alloys was tried for squeeze cast 6061 based composites with volume fractions of 0.5 and 0.32, and the matrix microhardness and resistivity changes during age hardening were studied. The matrix in the composites hardened much more than the unreinforced alloy. Microhardness increases of up to 70 VPN above the solution treated condition at various aging temperatures were observed. The resistivity variation indicated an appreciable state of internal stress which continued to persist even when hardness fell by overaging. Energy dispersive X-ray analysis indicated that the regionsmore » close to the fibers had a higher silicon content than the matrix, and amorphous silica in the fiber may have a role in the formation of an enriched layer which may help the bonding and strength in the composite.« less

The CEOS Atmospheric Composition Constellation: Enhancing the Value of Space-Based Observations

NASA Technical Reports Server (NTRS)

Eckman, Richard; Zehner, Claus; Al-Saadi, Jay

2015-01-01

The Committee on Earth Observation Satellites (CEOS) coordinates civil space-borne observations of the Earth. Participating agencies strive to enhance international coordination and data exchange and to optimize societal benefit. In recent years, CEOS has collaborated closely with the Group on Earth Observations (GEO) in implementing the Global Earth Observing System of Systems (GEOSS) space-based objectives. The goal of the CEOS Atmospheric Composition Constellation (ACC) is to collect and deliver data to improve monitoring, assessment and predictive capabilities for changes in the ozone layer, air quality and climate forcing associated with changes in the environment through coordination of existing and future international space assets. A project to coordinate and enhance the science value of a future constellation of geostationary sensors measuring parameters relevant to air quality supports the forthcoming European Sentinel-4, Korean GEMS, and US TEMPO missions. Recommendations have been developed for harmonization to mutually improve data quality and facilitate widespread use of the data products.

Influence of ocean tides on the diurnal and semidiurnal earth rotation variations from VLBI observations

NASA Astrophysics Data System (ADS)

Gubanov, V. S.; Kurdubov, S. L.

2015-05-01

The International astrogeodetic standard IERS Conventions (2010) contains a model of the diurnal and semidiurnal variations in Earth rotation parameters (ERPs), the pole coordinates and the Universal Time, arising from lunisolar tides in the world ocean. This model was constructed in the mid-1990s through a global analysis of Topex/Poseidon altimetry. The goal of this study is to try to estimate the parameters of this model by processing all the available VLBI observations on a global network of stations over the last 35 years performed within the framework of IVS (International VLBI Service) geodetic programs. The complexity of the problemlies in the fact that the sought-for corrections to the parameters of this model lie within 1 mm and, thus, are at the limit of their detectability by all currently available methods of ground-based positional measurements. This requires applying universal software packages with a high accuracy of reduction calculations and a well-developed system of controlling the simultaneous adjustment of observational data to analyze long series of VLBI observations. This study has been performed with the QUASAR software package developed at the Institute of Applied Astronomy of the Russian Academy of Sciences. Although the results obtained, on the whole, confirm a high accuracy of the basic model in the IERS Conventions (2010), statistically significant corrections that allow this model to be refined have been detected for some harmonics of the ERP variations.

Spatio-Temporal Variation in Landscape Composition May Speed Resistance Evolution of Pests to Bt Crops.

PubMed

Ives, Anthony R; Paull, Cate; Hulthen, Andrew; Downes, Sharon; Andow, David A; Haygood, Ralph; Zalucki, Myron P; Schellhorn, Nancy A

2017-01-01

Transgenic crops that express insecticide genes from Bacillus thuringiensis (Bt) are used worldwide against moth and beetle pests. Because these engineered plants can kill over 95% of susceptible larvae, they can rapidly select for resistance. Here, we use a model for a pyramid two-toxin Bt crop to explore the consequences of spatio-temporal variation in the area of Bt crop and non-Bt refuge habitat. We show that variability over time in the proportion of suitable non-Bt breeding habitat, Q, or in the total area of Bt and suitable non-Bt habitat, K, can increase the overall rate of resistance evolution by causing short-term surges of intense selection. These surges can be exacerbated when temporal variation in Q and/or K cause high larval densities in refuges that increase density-dependent mortality; this will give resistant larvae in Bt fields a relative advantage over susceptible larvae that largely depend on refuges. We address the effects of spatio-temporal variation in a management setting for two bollworm pests of cotton, Helicoverpa armigera and H. punctigera, and field data on landscape crop distributions from Australia. Even a small proportion of Bt fields available to egg-laying females when refuges are sparse may result in high exposure to Bt for just a single generation per year and cause a surge in selection. Therefore, rapid resistance evolution can occur when Bt crops are rare rather than common in the landscape. These results highlight the need to understand spatio-temporal fluctuations in the landscape composition of Bt crops and non-Bt habitats in order to design effective resistance management strategies.

Fourier Transform Infrared Imaging Microspectroscopy and Tissue-Level Mechanical Testing Reveal Intraspecies Variation in Mouse Bone Mineral and Matrix Composition

PubMed Central

Courtland, Hayden-William; Nasser, Philip; Goldstone, Andrew B.; Spevak, Lyudmila; Boskey, Adele L.; Jepsen, Karl J.

2009-01-01

Fracture susceptibility is heritable and dependent upon bone morphology and quality. However, studies of bone quality are typically overshadowed by emphasis on bone geometry and bone mineral density. Given that differences in mineral and matrix composition exist in a variety of species, we hypothesized that genetic variation in bone quality and tissue-level mechanical properties would also exist within species. Sixteen-week-old female A/J, C57BL/6J (B6), and C3H/HeJ (C3H) inbred mouse femora were analyzed using Fourier transform infrared imaging and tissue-level mechanical testing for variation in mineral composition, mineral maturity, collagen cross-link ratio, and tissue-level mechanical properties. A/J femora had an increased mineral-to-matrix ratio compared to B6. The C3H mineral-to-matrix ratio was intermediate of A/J and B6. C3H femora had reduced acid phosphate and carbonate levels and an increased collagen cross-link ratio compared to A/J and B6. Modulus values paralleled mineral-to-matrix values, with A/J femora being the most stiff, B6 being the least stiff, and C3H having intermediate stiffness. In addition, work-to-failure varied among the strains, with the highly mineralized and brittle A/J femora performing the least amount of work-to-failure. Inbred mice are therefore able to differentially modulate the composition of their bone mineral and the maturity of their bone matrix in conjunction with tissue-level mechanical properties. These results suggest that specific combinations of bone quality and morphological traits are genetically regulated such that mechanically functional bones can be constructed in different ways. PMID:18855037

Fourier transform infrared imaging microspectroscopy and tissue-level mechanical testing reveal intraspecies variation in mouse bone mineral and matrix composition.

PubMed

Courtland, Hayden-William; Nasser, Philip; Goldstone, Andrew B; Spevak, Lyudmila; Boskey, Adele L; Jepsen, Karl J

2008-11-01

Fracture susceptibility is heritable and dependent upon bone morphology and quality. However, studies of bone quality are typically overshadowed by emphasis on bone geometry and bone mineral density. Given that differences in mineral and matrix composition exist in a variety of species, we hypothesized that genetic variation in bone quality and tissue-level mechanical properties would also exist within species. Sixteen-week-old female A/J, C57BL/6J (B6), and C3H/HeJ (C3H) inbred mouse femora were analyzed using Fourier transform infrared imaging and tissue-level mechanical testing for variation in mineral composition, mineral maturity, collagen cross-link ratio, and tissue-level mechanical properties. A/J femora had an increased mineral-to-matrix ratio compared to B6. The C3H mineral-to-matrix ratio was intermediate of A/J and B6. C3H femora had reduced acid phosphate and carbonate levels and an increased collagen cross-link ratio compared to A/J and B6. Modulus values paralleled mineral-to-matrix values, with A/J femora being the most stiff, B6 being the least stiff, and C3H having intermediate stiffness. In addition, work-to-failure varied among the strains, with the highly mineralized and brittle A/J femora performing the least amount of work-to-failure. Inbred mice are therefore able to differentially modulate the composition of their bone mineral and the maturity of their bone matrix in conjunction with tissue-level mechanical properties. These results suggest that specific combinations of bone quality and morphological traits are genetically regulated such that mechanically functional bones can be constructed in different ways.

High temperature dynamic modulus and damping of aluminum and titanium matrix composites

NASA Technical Reports Server (NTRS)

Dicarlo, J. A.; Maisel, J. E.

1979-01-01

Dynamic modulus and damping capacity property data were measured from 20 to over 500 C for unidirectional B/Al (1100), B/Al (6061), B/SiC/Al (6061), Al2O3/Al, SiC/Ti-6Al-4V, and SiC/Ti composites. The measurements were made under vacuum by the forced vibration of composite bars at free-free flexural resonance near 2000 Hz and at amplitudes below 0.000001. Whereas little variation was observed in the dynamic moduli of specimens with approximately the same fiber content (50 percent), the damping of B/Al composites was found at all temperatures to be significantly greater than the damping of the Al2O3/Al and SiC/Ti composites. For those few situations where slight deviations from theory were observed, the dynamic data were examined for information concerning microstructural changes induced by composite fabrication and thermal treatment. The 270 C damping peak observed in B/Al (6061) composites after heat treatment above 460 C appears to be the result of a change in the 6061 aluminum alloy microstructure induced by interaction with the boron fibers. The growth characteristics of the damping peak suggest its possible value for monitoring fiber strength degration caused by excess thermal treatment during B/Al (6061) fabrication and use.

Positive and negative variations in capacitive images for given defects under varying experimental conditions

NASA Astrophysics Data System (ADS)

Li, Chen; Yin, Xiaokang; Li, Zhen; Li, Wei; Chen, Guoming

2018-04-01

Capacitive imaging (CI) technique is a novel electromagnetic NDE technique. The Quasi-static electromagnetic field from the carefully designed electrode pair will vary when the electrical properties of the sample change, leading to the possibility of imaging. It is observed that for a given specimen, the targeted features appear as different variations in capacitive images under different experimental conditions. In some cases, even opposite variations occur, which brings confusion to indication interpretation. It is thus thought interesting to embark on investigations into the cause and effects of the negative variation phenomenon. In this work, the positive and negative variations were first explained from the measurement sensitivity distribution perspective. This was then followed by a detailed analysis using finite element models in COMSOL. A parametric experimental study on a glass fiber composite plate with artificial defects was then carried out to investigate how the experimental conditions affect the variation.

MAVEN/IUVS Apoapse Observations of the Martian FUV Dayglow

NASA Astrophysics Data System (ADS)

Correira, J.; Evans, J. S.; Stevens, M. H.; Schneider, N. M.; Stewart, I. F.; Deighan, J.; Jain, S.; Chaffin, M.; Crismani, M. M. J.; McClintock, B.; Holsclaw, G.; Lefèvre, F.; Lo, D.; Stiepen, A.; Clarke, J. T.; Mahaffy, P. R.; Bougher, S. W.; Bell, J. M.; Jakosky, B. M.

2015-12-01

We present FUV data (115 - 190 nm) from MAVEN/IUVS apoapse mode observations for the Oct 2014 through Feb 2015 time period. During apoapse mode the highly elliptical orbit of MAVEN allows for up to four apoapse disk images by IUVS per day. Maps of FUV feature intensities and intensity ratios as well as derived CO/CO2 and O/CO2 column density ratios will be shown. Column density ratios are derived from lookup tables created using the Atmospheric Ultraviolet Radiance Integrated Code [Strickland et al., 1999] in conjunction with observed intensity ratios. Column density ratios provide a measure of composition changes in the Martian atmosphere. Due to MAVEN's orbital geometry the observations from this time period focus on the southern hemisphere. The broad view provided by apoapse observations allows for the investigation of spatial and temporal variations (both long term and local time) of the atmospheric composition (via the column density ratios). IUVS FUV intensities and derived column density ratios will also be compared with model results from Mars Global Ionosphere/Thermosphere Model (MGITM) and the Mars Climate Database (MCD).

Composite structural materials

NASA Technical Reports Server (NTRS)

Ansell, G. S.; Loewy, R. G.; Wiberley, S. E.

1984-01-01

Progress is reported in studies of constituent materials composite materials, generic structural elements, processing science technology, and maintaining long-term structural integrity. Topics discussed include: mechanical properties of high performance carbon fibers; fatigue in composite materials; experimental and theoretical studies of moisture and temperature effects on the mechanical properties of graphite-epoxy laminates and neat resins; numerical investigations of the micromechanics of composite fracture; delamination failures of composite laminates; effect of notch size on composite laminates; improved beam theory for anisotropic materials; variation of resin properties through the thickness of cured samples; numerical analysis composite processing; heat treatment of metal matrix composites, and the RP-1 and RP2 gliders of the sailplane project.

Secondary Inorganic Aerosols over an Urban Location in North-Western Himalayan Region: Seasonal Variation in Composition and Formation Process(es)

NASA Astrophysics Data System (ADS)

Kaushal, D.; Tandon, A.

2017-12-01

Oxidative photo-chemical transformation of precursor gases, mainly of anthropogenic origin, produces secondary aerosols. Secondary inorganic aerosols constitute a significant fraction of total aerosol load over urban locations especially high altitude in wet-temperate climatic set-up. Towns situated in North-Western Himalayan region (NWHR) with sizable population and attractive tourist destinations have been facing ever increasing problem of gaseous and particulate air pollution from exponential increase in vehicular traffic and other anthropogenic emissions. The present study has been planned to investigate the seasonal variations in atmospheric processes responsible for the formation of Secondary Inorganic Aerosols (SIA) and to estimate contribution of SIA to PM­10 load over an Urban location, Dharamshala, in Dhauladhar region of NWHR. Twenty four hourly PM10 aerosol samples were collected, on quartz micro fibre filters in Dharamshala (1350 amsl) on weekly basis for complete one year time-period (February 2015 - January 2016). These samples were analyzed for Water Soluble Inorganic Ions (WSII) using Ion-Chromatographic System. On annual basis, SO42- ions contributed maximum (52%) followed by NO3- (13%) and NH4+ (12%) to WSII. Based upon Principal Component Analysis (PCA), dominant sources contributing to PM10 associated WSII were identified as: Fossil-Fuel and Bio-mass burning, Vehicular (mainly diesel) emissions and gaseous emissions from the microbial degradation of dead bio-mass. Throughout the year, significantly high proportion of SO42- and considerable thermodynamic stability of (NH4)2SO2 at ambient temperatures, made it the major contributor to SIA over NH4NO3 and NH4Cl. On seasonal basis, maximum contribution of SIA to PM10 was observed in monsoon followed by the winter season. Low ambient temperature in winter season favoured formation of NH4NO3 with significant contribution to SIA. It could be concluded that observed variability in the composition and

Promise and Capability of NASA's Earth Observing System to Monitor Human-Induced Climate Variations

NASA Technical Reports Server (NTRS)

King, M. D.

2003-01-01

The Earth Observing System (EOS) is a space-based observing system comprised of a series of satellite sensors by which scientists can monitor the Earth, a Data and Information System (EOSDIS) enabling researchers worldwide to access the satellite data, and an interdisciplinary science research program to interpret the satellite data. The Moderate Resolution Imaging Spectroradiometer (MODIS), developed as part of the Earth Observing System (EOS) and launched on Terra in December 1999 and Aqua in May 2002, is designed to meet the scientific needs for satellite remote sensing of clouds, aerosols, water vapor, and land and ocean surface properties. This sensor and multi-platform observing system is especially well suited to observing detailed interdisciplinary components of the Earth s surface and atmosphere in and around urban environments, including aerosol optical properties, cloud optical and microphysical properties of both liquid water and ice clouds, land surface reflectance, fire occurrence, and many other properties that influence the urban environment and are influenced by them. In this presentation I will summarize the current capabilities of MODIS and other EOS sensors currently in orbit to study human-induced climate variations.

No Timing Variations Observed in Third Transit of Snow-line Exoplanet Kepler-421b

NASA Astrophysics Data System (ADS)

Dalba, Paul A.; Muirhead, Philip S.

2016-07-01

We observed Kepler-421 during the anticipated third transit of the snow-line exoplanet Kepler-421b in order to constrain the existence and extent of transit timing variations (TTVs). Previously, the Kepler spacecraft only observed two transits of Kepler-421b, leaving the planet’s transit ephemeris unconstrained. Our visible light, time-series observations from the 4.3 m Discovery Channel Telescope were designed to capture pre-transit baseline and the partial transit of Kepler-421b, barring significant TTVs. We use the light curves to assess the probabilities of various transit models using both the posterior odds ratio and the Bayesian Information Criterion, and find that a transit model with no TTVs is favored to 3.6σ confidence. These observations suggest that Kepler-421b is either alone in its system or is only experiencing minor dynamic interactions with an unseen companion. With the Kepler-421b ephemeris constrained, we calculate future transit times and discuss the opportunity to characterize the atmosphere of this cold, long-period exoplanet via transmission spectroscopy. Our investigation emphasizes the difficulties associated with observing long-period exoplanet transits and the consequences that arise from failing to refine transit ephemerides.

Hydrological storage variations in a lake water balance, observed from multi-sensor satellite data and hydrological models.

NASA Astrophysics Data System (ADS)

Singh, Alka; Seitz, Florian; Schwatke, Christian; Guentner, Andreas

2013-04-01

Freshwater lakes and reservoirs account for 74.5% of continental water storage in surface water bodies and only 1.8% resides in rivers. Lakes and reservoirs are a key component of the continental hydrological cycle but in-situ monitoring networks are very limited either because of sparse spatial distribution of gauges or national data policy. Monitoring and predicting extreme events is very challenging in that case. In this study we demonstrate the use of optical remote sensing, satellite altimetry and the GRACE gravity field mission to monitor the lake water storage variations in the Aral Sea. Aral Sea is one of the most unfortunate examples of a large anthropogenic catastrophe. The 4th largest lake of 1960s has been decertified for more than 75% of its area due to the diversion of its primary rivers for irrigation purposes. Our study is focused on the time frame of the GRACE mission; therefore we consider changes from 2002 onwards. Continuous monthly time series of water masks from Landsat satellite data and water level from altimetry missions were derived. Monthly volumetric variations of the lake water storage were computed by intersecting a digital elevation model of the lake with respective water mask and altimetry water level. With this approach we obtained volume from two independent remote sensing methods to reduce the error in the estimated volume through least square adjustment. The resultant variations were then compared with mass variability observed by GRACE. In addition, GARCE estimates of water storage variations were compared with simulation results of the Water Gap Hydrology Model (WGHM). The different observations from all missions agree that the lake reached an absolute minimum in autumn 2009. A marked reversal of the negative trend occured in 2010 but water storage in the lake decreased again afterwards. The results reveal that water storage variations in the Aral Sea are indeed the principal, but not the only contributor to the GRACE signal of

Local, Regional, and Global Albedo Variations on Mars From Recent Space-Based Observations: Implications for Future Human Explorers

NASA Astrophysics Data System (ADS)

Bell, J. F.; Wellington, D. F.

2017-06-01

We describe recent as well as historic albedo variations on Mars as observed by space-based telescopes, orbiters, and surface missions, and speculate that some regions might offer fewer dust-related problems for future human explorers than others.

Chromatin organization in sperm may be the major functional consequence of base composition variation in the human genome.

PubMed

Vavouri, Tanya; Lehner, Ben

2011-04-01

Chromatin in sperm is different from that in other cells, with most of the genome packaged by protamines not nucleosomes. Nucleosomes are, however, retained at some genomic sites, where they have the potential to transmit paternal epigenetic information. It is not understood how this retention is specified. Here we show that base composition is the major determinant of nucleosome retention in human sperm, predicting retention very well in both genic and non-genic regions of the genome. The retention of nucleosomes at GC-rich sequences with high intrinsic nucleosome affinity accounts for the previously reported retention at transcription start sites and at genes that regulate development. It also means that nucleosomes are retained at the start sites of most housekeeping genes. We also report a striking link between the retention of nucleosomes in sperm and the establishment of DNA methylation-free regions in the early embryo. Taken together, this suggests that paternal nucleosome transmission may facilitate robust gene regulation in the early embryo. We propose that chromatin organization in the male germline, rather than in somatic cells, is the major functional consequence of fine-scale base composition variation in the human genome. The selective pressure driving base composition evolution in mammals could, therefore, be the need to transmit paternal epigenetic information to the zygote.

Boron Isotopic Composition Correlates with Ultra-Structure in a - Sea Coral Lophelia Pertusa: Implications for Biomineralization and - PH