Science.gov

Sample records for observed energy-dependent composition

  1. Energy dependence of fission observables

    NASA Astrophysics Data System (ADS)

    Paşca, Horia

    2016-01-01

    The mass, charge and isotopic distributions of fission fragments are studied within an improved scission-point statistical model in the reaction 235U+n at different energies of the incident neutron. The available experimental data are well reproduced and the energy-dependencies of the observable characteristics of fission are predicted for future experiments. The calculated mass distribution of 238U+n is also compared with experimental data.

  2. Observed antiprotons and energy dependent confinement of cosmic rays: A conflict?

    NASA Technical Reports Server (NTRS)

    Stephens, S. A.

    1985-01-01

    In the frame work of energy dependent confinement for cosmic rays, the energy spectrum inside the source is flatter than that observed. Antiproton observation suggests large amount of matter is being traversed by cosmic rays in some sources. As a result, secondary particles are produced in abundance. Their spectra was calculated and it is shown that the energy dependent confinement model is in conflict with some observations.

  3. Solar flare particles - Energy-dependent composition and relationship to solar composition

    NASA Technical Reports Server (NTRS)

    Crawford, H. J.; Price, P. B.; Cartwright, B. G.; Sullivan, J. D.

    1975-01-01

    Plastic and glass track detectors on rockets and Apollo spacecraft have been used to determine the composition of particles from He to Ni at energies from 0.1 to 50 MeV per nucleon in several solar flares of widely varying intensities. At low energies the composition of solar particles is enriched in heavy elements by an amount, relative to the asymptotic high-energy composition, that increases with atomic number from Z = 2 up to at least Z = 50, that decreases with energy, and that varies from flare to flare. At high energies (usually beyond an energy of 5 to 20 MeV per nucleon) the composition becomes independent of energy and, though somewhat variable from flare to flare, approximates the composition of the solar atmosphere. A table of abundances of the even-Z elements from He to Ni (plus N) in solar particles is constructed by averaging the asymptotic high-energy abundances in several flares.

  4. Results on the energy dependence of cosmic-ray charge composition

    NASA Technical Reports Server (NTRS)

    Balasubrahmanyan, V. K.; Ormes, J. F.

    1973-01-01

    Results of measurements by a balloon-borne ionization spectrometer of the energy dependence of high-energy cosmic-ray charge composition. The results presented are greatly improved over those obtained earlier by Ormes et al. (1971) by the use of a multidimensional charge analysis with more efficient background rejection, and a more accurate energy determination. Complex couplings between the charge, energy, and trajectory information were taken into account and are discussed. The spectra of individual elements up to oxygen and of groups of nuclei up through iron were measured up to almost 100 GeV per nucleon. The energy spectrum of the secondary nuclei, B + N, is found to be steeper than that of the primary nuclei, C + O, in agreement with Smith et al. (1973). The most dramatic finding is that the spectrum of the iron nuclei is flatter than that of the carbon and oxygen nuclei by 0.57 plus or minus 0.14 of a power.

  5. Energy dependence of fluctuation and correlation observables of transverse momentum in heavy-ion collisions

    NASA Astrophysics Data System (ADS)

    Novak, John F.

    be a conclusive indication of the QGP critical point, is observed. Some anomalous behavior of the higher moments is noted which will require further analysis. Dynamic fluctuations of the distribution, as measured by the two particle correlator Dpt,i, Dpt,j and the higher moments of the distribution, are observed to increase with energy. There is a strong energy dependence below NsN =19.6GeV , and the dynamic fluctuations of are consistent with zero at 7.7 GeV.

  6. Energy dependence of cosmic ray composition above 10(15) GeV/nucleus

    NASA Technical Reports Server (NTRS)

    Linsley, J.; Fichtel, C. E.

    1985-01-01

    It is argued that above 10 to the 5th power GeV/nucleus, in the range where charge-resolved spectra have not yet been determined, the appropriate measures of equal-energy composition are 1nA and 1nA , the mean value and dispersion relative to the mean value and dispersion relative to the mean of 1nA, where A is the mass number. Experimental data which are sensitive to changes in 1nA with increasing energy are examined. It is found that, taken as a whole, they show no change (+ or 0.5) between 10 to the 5th power and 10 to the 6th power GeV, and a decrease of 1.5 + or - 0.5 between 10 to the 6th power and 10 to the 8th power GeV, with no further change + or - 0.5) above 10 to the 8th power GeV. Taken as a whole, the various indirect estimates of the absolute value of 1nA above 10 to the 5th power GeV/nucleus are also consistent with this pattern. For a wide range of astrophysically plausible composition models the value of the other measure, 1nA is insensitive to changes in 1nA . Because of this the existing data on 1nA can likewise easily be reconciled with this pattern.

  7. Bounds on an energy-dependent and observer-independent speed of light from violations of locality.

    PubMed

    Hossenfelder, Sabine

    2010-04-01

    We show that models with deformations of special relativity that have an energy-dependent speed of light have nonlocal effects. The requirement that the arising nonlocality is not in conflict with known particle physics allows us to derive strong bounds on deformations of special relativity and rule out a modification to first order in energy over the Planck mass. PMID:20481922

  8. Bounds on an Energy-Dependent and Observer-Independent Speed of Light from Violations of Locality

    SciTech Connect

    Hossenfelder, Sabine

    2010-04-09

    We show that models with deformations of special relativity that have an energy-dependent speed of light have nonlocal effects. The requirement that the arising nonlocality is not in conflict with known particle physics allows us to derive strong bounds on deformations of special relativity and rule out a modification to first order in energy over the Planck mass.

  9. Reproducing the observed energy-dependent structure of Earth's electron radiation belts during storm recovery with an event-specific diffusion model

    NASA Astrophysics Data System (ADS)

    Ripoll, J.-F.; Reeves, G. D.; Cunningham, G. S.; Loridan, V.; Denton, M.; Santolík, O.; Kurth, W. S.; Kletzing, C. A.; Turner, D. L.; Henderson, M. G.; Ukhorskiy, A. Y.

    2016-06-01

    We present dynamic simulations of energy-dependent losses in the radiation belt "slot region" and the formation of the two-belt structure for the quiet days after the 1 March storm. The simulations combine radial diffusion with a realistic scattering model, based data-driven spatially and temporally resolved whistler-mode hiss wave observations from the Van Allen Probes satellites. The simulations reproduce Van Allen Probes observations for all energies and L shells (2-6) including (a) the strong energy dependence to the radiation belt dynamics (b) an energy-dependent outer boundary to the inner zone that extends to higher L shells at lower energies and (c) an "S-shaped" energy-dependent inner boundary to the outer zone that results from the competition between diffusive radial transport and losses. We find that the characteristic energy-dependent structure of the radiation belts and slot region is dynamic and can be formed gradually in ~15 days, although the "S shape" can also be reproduced by assuming equilibrium conditions. The highest-energy electrons (E > 300 keV) of the inner region of the outer belt (L ~ 4-5) also constantly decay, demonstrating that hiss wave scattering affects the outer belt during times of extended plasmasphere. Through these simulations, we explain the full structure in energy and L shell of the belts and the slot formation by hiss scattering during storm recovery. We show the power and complexity of looking dynamically at the effects over all energies and L shells and the need for using data-driven and event-specific conditions.

  10. Scattering with absorptive interaction: Energy-dependent potentials

    NASA Astrophysics Data System (ADS)

    Cassing, W.; Stingl, M.; Weiguny, A.

    1983-05-01

    The energy dependence and analytic structure of the effective interaction for elastic scattering of composite particles are investigated using Feshbach's projection technique. A generalized Levinson theorem is established for complex, nonlocal, and energy-dependent interactions. The analytical results are illustrated by means of Argand diagrams for a solvable model and the effect of energy averaging is discussed. NUCLEAR REACTIONS Scattering theory, S matrix for absorptive, energy-dependent potentials, Levinson theorem.

  11. Observational constraints on the composition of exoplanets

    NASA Astrophysics Data System (ADS)

    Griffith, C. A.; Tinetti, G.; Swain, M. R.; Deroo, P.; Cunha, K.; Schuler, S.; Freedman, R.

    2011-10-01

    Two forms of exoplanetary spectra can be measured. The primary eclipse provides a transmission spectra of the exoplanet's limb as the planet passes in front of the star. The secondary eclipse measures the emission of mainly the planet's dayside atmosphere from the planet plus star's emission minus the emission of star alone, when it eclipses the planet. In the past 3 years, infrared transmission and emission spectroscopy have revealed the presence of the primary carbon and oxygen species (CH4, CO2, CO, and H2O). Yet, efforts to constrain the abundances of these molecules are hindered by degenerate effects of the temperature and composition in the emission spectra, and the composition and assumed radius in the transmission spectrum. These degeneracies lead to derived mixing ratios that span several orders of magnitude. This talk will discuss the correlations in the degenerate solutions that result from the radiative transfer analyses of both emission and transmission spectroscopy. We present an analysis of primary and secondary transit observations of HD209458b's optical to infrared spectra, and correlate the degenerate effects of the atmospheric parameters using a principal components analysis to better constrain the atmospheric composition of the exoplanet. The derived oxygen and carbon composition of the HD209458b's atmosphere are considered in conjunction with the primary star's composition in order to start to address questions regarding the evolution of the exoplanet.

  12. A new observational solar irradiance composite

    NASA Astrophysics Data System (ADS)

    Schoell, Micha; Dudok de Wit, Thierry; Haberreiter, Margit; Kretzschmar, Matthieu; Misios, Stergios; Tourpali, Klairie; Schmutz, Werner

    2016-04-01

    Variations of the spectral solar irradiance (SSI) are an important driver for the chemistry, temperature and dynamics of the Earth's atmosphere and ultimately the Earth's climate. Due to the sparce and scattered SSI data sets it is important to establish tools to derive a consistent SSI dataset, including realistic uncertainties. We present the a new SSI composite based on the face values of SSI observations and applying a probabilistic method that takes into account the uncertainty of the data set scale-wise. We will present the data set and discuss its effects on the Earth's atmosphere in relation to SSI reconstruction models.

  13. Tropospheric Composition Change observed from Space (Invited)

    NASA Astrophysics Data System (ADS)

    Richter, A.; Hilboll, A.; Leitao, J.; Vrekoussis, M.; Wittrock, F.; Burrows, J. P.

    2010-12-01

    The composition of the troposphere is largely influenced by surface emissions of both natural and anthropogenic origins. These emissions change over time as result of human activities and natural variability, leading to varying atmospheric levels of primary and secondary pollutants. Satellite observations of sun light scattered back by the surface and the atmosphere can be used to retrieve information on atmospheric trace gases by application of optical absorption spectroscopy. In the UV and visible part of the spectrum, these measurements have good sensitivity to the lower troposphere providing information on relevant species such as O3, NO2, SO2, HCHO or glyoxal. Here, we report on recent results on tropospheric composition changes obtained from the GOME, SCIAMACHY and GOME-2 instruments which have a combined data record of nearly 15 years. The focus is on NO2 which shows an increasing trend over Asia and many large cities in countries with growing economies. At the same time, significant reductions are observed over the US and Europe, probably as result of changes in environmental legislation. SO2 signals have been decreasing over the US since 1996 while a strong upward trend was evident over China until recently when desulphurisation of power plant emissions came into effect. There also is evidence for increases in VOC levels over China which could be either of anthropogenic origin or from biogenic emissions.

  14. Morphology Composition Isotopes: Recent Results from Observations

    NASA Astrophysics Data System (ADS)

    Schulz, R.

    2008-07-01

    This article presents some recent imaging and spectroscopic observations that led to results which are significant for understanding the properties of comet nuclei. The coma morphology and/or composition were investigated for 12 comets belonging to different dynamical classes. The data analysis showed that the coma morphology of three non-periodic comets is not consistent with the general assumption that dynamically new comets still have a relatively uniform nucleus surface and therefore do not exhibit gas and/or dust jets in their coma. The determination of carbon and nitrogen isotopic ratios revealed the same values for all comets investigated at various heliocentric distances. However, the relative abundance of the rare nitrogen isotope 15N is about twice as high as in the Earth’s atmosphere. Observations of comets at splitting events and during outbursts led to indications for differences between material from the nucleus surface and the interior. The monitoring of the induced outburst of 9P/Temple revealed that under non-steady state conditions the fast disintegration of species is detectable.

  15. Composition of Ultra High Energy Cosmic Rays Observed by Telescope Array in Hybrid Mode

    NASA Astrophysics Data System (ADS)

    Hanlon, William; Telescope Array Collaboration

    2016-03-01

    The energy spectrum of cosmic rays exhibits several important features such as the knee (E ~10 15 . 5 eV), ankle (E ~10 18 . 7 eV), and high energy suppression (E ~10 19 . 8 eV). Cosmic ray chemical composition is the key to understanding their galactic and extragalactic sources as well as the origin of particle production and acceleration mechanisms. Energy dependent chemical composition is a fundamental input for models of cosmic ray sources and interstellar transport which may lead to competing explanations of the observed spectral features. Understanding composition will therefore allow one to distinguish between the different scenarios of cosmic ray origin, a decades old problem in astrophysics. In this talk we will describe measurements of ultra high energy cosmic ray composition performed by Telescope Array (TA) using Xmax measured in extended air showers (EAS) simultaneously observed by the TA surface array and TA fluorescence stations (called hybrid mode). Showers with primary energies above 1018 eV will be considered. We will also discuss improved methods of comparing the measured composition to EAS models.

  16. Middle atmosphere composition revealed by satellite observations

    NASA Technical Reports Server (NTRS)

    Russell, J. M., III; Solomon, S.; Mccormick, M. P.; Miller, A. J.; Barnett, J. J.; Jones, R. L.; Rusch, D. W.

    1986-01-01

    A series of plots that describe the state of the stratosphere and to some degree, the mesosphere as revealed by satellite observations are shown. The pertinent instrument features, spatial and temporal coverage, and details of accuracy and precision for the experiments providing the data were described. The main features of zonal mean cross sections and polar stereographic projections were noted and intercomparisons were discussed where a parameter was measured by more than one experiment. The main purpose was to collect the available data in one place and provide enough inforamation on limitations or cautions about the data so that they could be used in model comparisons and science studies.

  17. 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.

  18. Compositional Ground Truth of Diviner Lunar Radiometer Observations

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

    The Moon affords us a unique opportunity to "ground truth" thermal infrared (i.e. 3 to 25 micron) observations of an airless body. The Moon is the most accessable member of the most abundant class of solar system bodies, which includes Mercury, astroids, and icy satellites. The Apollo samples returned from the Moon are the only extraterrestrial samples with known spatial context. And the Diviner Lunar Radiometer (Diviner) is the first instrument to globally map the spectral thermal emission of an airless body. Here we compare Diviner observations of Apollo sites to compositional and spectral measurements of Apollo lunar soil samples in simulated lunar environment (SLE).

  19. 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.

  20. CRRES observations of stormtime ring current ion composition

    SciTech Connect

    Roeder, J.L.; Fennell, J.F.; Chen, M.W.; Grande, M.; Livi, S.; Schulz, M.

    1996-07-01

    The Magnetospheric Ion Composition Spectrometer onboard the CRRES spacecraft provided mass and charge state composition data for positive ions in the energy-per-charge range 1{endash}426 keV/e. The CRRES data is compared to the AMPTE/CCE observations during a moderately large geomagnetic storm on 4 June 1991. The results are compared to observations of large storms by CRRES and by the AMPTE/CCE spacecraft. The CRRES data show that oxygen ions formed 29{percent} of the total measured ion energy density at {ital L}=3{endash}5 during the storm recovery phase. This result implies that domination of the plasma by oxygen ions may not be necessary to produce the observed rapid initial recovery of the {ital D}st magnetic index. A preliminary test of the Dessler-Parker-Sckopke relation between the ion energy and the global magnetic perturbation shows that the observed particle fluxes during the 4 June 1991 storm could account for only 40{endash}70{percent} of the variation of {ital D}st. {copyright} {ital 1996 American Institute of Physics.}

  1. Saturn's Atmospheric Composition from Observations by the Cassini/Composite Infrared Spectrometer

    NASA Technical Reports Server (NTRS)

    Abbas, M. M.; Young, M.; LeClair, A. C.; Achterberg, R. K.; Flasar, F. M.; Kunde, V. G.

    2010-01-01

    Thermal emission infrared observation of Saturn s atmosphere are being made by the Composite Infrared Spectrometer (CIRS) aboard the Cassini spacecraft since its insertion in Saturn s orbit on July 2nd, 2004. The measurements made in both limb and nadir modes of observations consist of infrared spectra in the 10-1400/cm region with a variable spectral resolution of 0.53/cm and 2.8/cm, and exhibit rotational and vibrational spectral features that may be analyzed for retrieval of the thermal structure and constituent distribution of Saturn s atmosphere. In this paper, we present a comprehensive analysis of the CIRS infrared observed spectra for retrieval of Saturn s atmospheric composition focusing on the distributions of some selected hydrocarbons, phosphine, ammonia, and possible determination of the isotopic ratios of some species with sufficiently strong isolated spectral features. A comparison of the retrieved constituent distributions with the available data in the literature will be made.

  2. Compositional Variations from UVIS Observations of Titan's Dayglow and Comparisons with in situ INMS Observations

    NASA Astrophysics Data System (ADS)

    Stevens, M. H.; Evans, J. S.; Ajello, J. M.; Bradley, E. T.; Meier, R. R.; Westlake, J. H.; Waite, J. H., Jr.

    2012-04-01

    The Cassini Ultraviolet Imaging Spectrograph (UVIS) observed Titan’s dayside limb on multiple occasions between 2007 and 2011. The airglow observations reveal the same variety of EUV (600-1150Å) and FUV (1150-1900Å) emissions arising from photoelectron excitation and photofragmentation of molecular nitrogen (N2) on Earth. Through spectral analysis we extract radiance profiles for each set of UVIS limb emissions in the EUV and FUV, which are attenuated by methane (CH4). Using a terrestrial airglow model adapted to Titan, we derive the N2 and CH4 density profiles using the prescribed solar irradiance for the relevant Cassini orbit and compare the calculated radiance profiles directly with observations. We find that the UVIS airglow observations can be explained by solar driven processes, although fluctuations in the observed airglow between flybys suggest compositional changes in the background atmosphere. We compare the compositional variations inferred from the UVIS airglow to in situ observations by the Cassini Ion and Neutral Mass Spectrometer (INMS) from the same Titan orbit and discuss how the variations may be related to Titan’s varying plasma environment.

  3. 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.

  4. Energy dependence corrections to MOSFET dosimetric sensitivity.

    PubMed

    Cheung, T; Butson, M J; Yu, P K N

    2009-03-01

    Metal Oxide Semiconductor Field Effect Transistors (MOSFET's) are dosimeters which are now frequently utilized in radiotherapy treatment applications. An improved MOSFET, clinical semiconductor dosimetry system (CSDS) which utilizes improved packaging for the MOSFET device has been studied for energy dependence of sensitivity to x-ray radiation measurement. Energy dependence from 50 kVp to 10 MV x-rays has been studied and found to vary by up to a factor of 3.2 with 75 kVp producing the highest sensitivity response. The detectors average life span in high sensitivity mode is energy related and ranges from approximately 100 Gy for 75 kVp x-rays to approximately 300 Gy at 6 MV x-ray energy. The MOSFET detector has also been studied for sensitivity variations with integrated dose history. It was found to become less sensitive to radiation with age and the magnitude of this effect is dependant on radiation energy with lower energies producing a larger sensitivity reduction with integrated dose. The reduction in sensitivity is however approximated reproducibly by a slightly non linear, second order polynomial function allowing corrections to be made to readings to account for this effect to provide more accurate dose assessments both in phantom and in-vivo. PMID:19400548

  5. Titan's stratospheric composition from Cassini/CIRS observations

    NASA Astrophysics Data System (ADS)

    Coustenis, A.; Conrath, B.; Achterberg, R.; Jennings, D.; Bjoraker, G.; Flasar, M.; Nixon, C.; Romani, P.; Samuelson, R.; Bézard, B.; Lellouch, E.; Courtin, R.; Lellouch, E.; Marten, A.; Vinatier, S.; Fouchet, Th.; Irwin, P.; Teanby, N.; Abbas, M.; CIRS Investigation Team

    2005-08-01

    We have analyzed data recorded by the Composite Infrared Spectrometer (CIRS) aboard the Cassini mission during the recent Titan fly-bys (October 2004- June 2005). The spectra characterize various regions on Titan from south to north pole with a large spectrum of emission angles. We study the emission observed in the 3 CIRS detectors (covering roughly the 10-1500 cm-1 spectral range with a 0.53 cm-1 apodized resolution at best). The composite spectrum shows several molecular signatures : hydrocarbons, nitriles and 3 oxygen components. We have used temperature profiles retrieved by inversion of the emission observed in the methane ν 4 band at 1304 cm-1 and a line-by-line radiative transfer code to infer the abundances of the trace constituents and some of their isotopes in Titan's stratosphere. Information is retrieved on the meridional variation of the trace constituents. We will compare these mixing ratios with values retrieved two Titan seasons ago by V1 and V2 IRIS observations, with more recent disk-averaged Infrared Space Observatory (ISO) results and with the latest Cassini-Huygens inferences from other instruments in an attempt to tie our findings to the seasonal phenomena on Titan. References Flasar, F. M., Achterberg R. K., Conrath B. J., Gierasch, P. J., Kunde V. G., Nixon C. A., Bjoraker G. L., Jennings D. E., Romani P. N., Simon-Miller A. A., Bézard B., Coustenis A., Irwin P. G. J., Teanby, N. A., Brasunas J., Pearl J. C., Segura, M. E., Carlson, R., Matmoukine, A., Schinder, P. J., Barucci A., Courtin R., Fouchet T., Gautier D., Lellouch E., Marten A., Prangé, R., Vinatier, S., Strobel, D. F., Calcutt S. B., Read P. L., Taylor, F. W., Bowles, N., Samuelson R. E., Orton G. S., Spilker L. J., Owen T. C., Spencer, J. A., Showalter, M. R., Ferrari, C., Abbas M. M., Raulin F., Edgington, S., Ade P., Wishnow, E. H. 2005. Titan's atmospheric temperatures, winds, and composition. Science, 308, 975-978.

  6. Ion composition and drift observations in the nighttime equatorial ionosphere

    NASA Technical Reports Server (NTRS)

    Goldberg, R. A.; Aikin, A. C.; Murthy, B. V. K.

    1974-01-01

    The first in situ measurements of ion composition in the nighttime equatorial E and F region ionospheres (90-300 km) are presented and discussed. These profiles were obtained by two rocket-borne ion mass spectrometers launched from Thumba, India on March 9-10, 1970 at solar zenith angles of 112 deg and 165 deg. Ionosonde data established that the composition was measured at times bounding a period of F region downward drift. During this period the ions O(+) and N(+) were enhanced by one to three orders of magnitude between 220 and 300 km. Below the drift region (200 km), O(+) ceased to be the major ionic constituent, but the concentrations of O(+) and N(+) remained larger than predicted from known radiation sources and loss processes. Here also, both the O2(+) and NO(+) profiles retained nearly the same shape and magnitude throughout the night in agreement with theories assuming scattered UV radiation to be the maintaining source. Light metallic ions including Mg(+), Na(+) and possibly Si(+) were observed to altitude approaching 300 km, while the heavier ions Ca(+) and K(+) were seen in reduced quantity to 200 km. All metal ion profiles exhibited changes which can be ascribed to vertical drifting.

  7. Composite disturbance rejection control based on generalized extended state observer.

    PubMed

    Zhang, Yanjun; Zhang, Jun; Wang, Lu; Su, Jianbo

    2016-07-01

    Traditional extended state observer (ESO) design method does not focus on analysis of system reconstruction strategy. The prior information of the controlled system cannot be used for ESO implementation to improve the control accuracy. In this paper, composite disturbance rejection control strategy is proposed based on generalized ESO. First, the disturbance rejection performance of traditional ESO is analyzed to show the essence of the reconstruction strategy. Then, the system is reconstructed based on the equivalent disturbance model. The generalized ESO is proposed based on the reconstructed model, while convergence of the proposed ESO is analyzed along with the outer loop feedback controller. Simulation results on a second order mechanical system show that the proposed generalized ESO can deal with the external disturbance with known model successfully. Experiment of attitude tracking task on an aircraft is also carried out to show the effectiveness of the proposed method. PMID:27129764

  8. Morphology-Composition-Isotopes: Recent Results from Observations

    NASA Astrophysics Data System (ADS)

    Schulz, R.

    This article presents some recent imaging and spectroscopic observations that led to results which are significant for understanding the properties of comet nuclei. The coma morphology and/or composition were investigated for 12 comets belonging to different dynamical classes. The data analysis showed that the coma morphology of three non-periodic comets is not consistent with the general assumption that dynamically new comets still have a relatively uniform nucleus surface and therefore do not exhibit gas and/or dust jets in their coma. The determination of carbon and nitrogen isotopic ratios revealed the same values for all comets investigated at various heliocentric distances. However, the relative abundance of the rare nitrogen isotope 15N is about twice as high as in the Earth's atmosphere. Observations of comets at splitting events and during outbursts led to indications for differences between material from the nucleus surface and the interior. The monitoring of the induced outburst of 9P/Temple revealed that under non-steady state conditions the fast disintegration of species is detectable.

  9. 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

  10. Compositing radar reflectivity observations with an inverse method

    NASA Astrophysics Data System (ADS)

    Roca-Sancho, Jordi; Berenguer, Marc; Sempere-Torres, Daniel

    2013-04-01

    Quantitative Precipitation Estimation (QPE) has been one of the main applications of weather radars since its early stages. Nowadays, many advances have improved such estimates and radar networks have been deployed in many countries. In parallel, uncertainty in radar QPE has become a subject of interest by itself because of its significant role in the quality of estimates. When several radars cover the same area, some sources of uncertainty (e.g. path attenuation by intense precipitation, beam blockage or beam broadening), can be dealt using information from the least-affected radars instead of only reproducing a single radar approach in each one. So far, composites of radar observations are carried out through simple criteria (by picking the closest observation, the maximum value…) or quality indices -that need a priori definition of quality descriptors. This study proposes an alternative methodology to retrieve the 3-dimensional reflectivity field most compatible with the measurements from the different radars of the network. With this aim, the methodology uses a model that simulates the radar sampling of the atmosphere. The model settings consider the specific features of each radar such as the location, hardware parameters (frequency, beam width, pulse length…) and scanning strategy. The methodology follows the concept of an inverse method based on the minimization of a cost function that penalizes discrepancies between the simulated and actual observations for each radar of the network. It is worth noting that for radar at attenuating wavelengths, the proposed methodology implicitly corrects the effect of attenuation due to intense rainfall. The methodology has been applied on the network of C-band radars in the vicinity of Barcelona, Spain. The retrievals have been obtained for a 12 hours of rainfall with reflectivity observations of two radars; observations from a third independent radar have been used for verification at different heights. Conventional

  11. ECCO: The extremely heavy cosmic ray composition observer

    SciTech Connect

    Westphal, A. J.; Weaver, B. A.; Solarz, M.; Price, P. B.; Lin, C.-L.

    1999-01-22

    Using the Trek ultraheavy galactic cosmic ray collector onboard Mir, we have measured the abundances of even-Z elements from {sub 76}Os through the actinides in the galactic cosmic rays, with a charge resolution of {approx}0.45e, roughly a three-fold improvement in resolution over pioneering measurements by HEAO, Ariel, and UHCRE onboard LDEF. Building on the successful design of Trek, we plan to design and construct ECCO, a large array of BP-1 glass track-etch detectors which would be deployed on the International Space Station. ECCO, the Extremely Heavy Cosmic Ray Composition Observer, would have sufficient charge resolution and collecting power to accurately measure the abundances of the very rare actinides with respect to each other and with respect to the platinum-group. These abundance measurements will strongly distinguish between models of GCR origin. We are verifying a promising new detector concept, which would result in significant cost savings, and would have several technical advantages over previous detector configurations; also, we are testing an advanced gas-transfer hodoscope for ECCO. Finally, we are constructing mockup ECCO modules for flight testing in preparation for a launch in 2003 and supporting an accommodation and design study for ECCO at GSFC.

  12. Satellite Observations for Detecting and Tracking Changes in Atmospheric Composition

    EPA Science Inventory

    The international scientific community's Integrated Global Atmosphere Chemistry Observation System report outlined a plan for ground-based, airborne and satellite Measurements, and models to integrate the observations into a 4-dimensional representation of the atmosphere (space a...

  13. CRRES observations of ion composition during EMIC mode wave events

    SciTech Connect

    Macdonald, Elizabeth; Larsen, Brian

    2010-12-13

    EMIC mode waves may play an important role in the dynamics of the growth and loss of the radiation belts. CRRES mission analysis has provided extensive information on the distributions of EMIC mode waves. Less well studied and understood is the role that ion composition plays in the formation of the EMIC mode waves. The CRESS plasma mass spectrometer LOMICS measured all ion species of interest up to 45 keV/q. This preliminary study will examine the characteristics of heavy ions during a multitude of wave events, in particular, the effect of ion composition on wave-particle interactions, amplitude, and frequency. The relevance of such data to the upcoming RBSP mission will be highlighted.

  14. Nonlinear thermoelectric response due to energy-dependent transport properties of a quantum dot

    NASA Astrophysics Data System (ADS)

    Svilans, Artis; Burke, Adam M.; Svensson, Sofia Fahlvik; Leijnse, Martin; Linke, Heiner

    2016-08-01

    Quantum dots are useful model systems for studying quantum thermoelectric behavior because of their highly energy-dependent electron transport properties, which are tunable by electrostatic gating. As a result of this strong energy dependence, the thermoelectric response of quantum dots is expected to be nonlinear with respect to an applied thermal bias. However, until now this effect has been challenging to observe because, first, it is experimentally difficult to apply a sufficiently large thermal bias at the nanoscale and, second, it is difficult to distinguish thermal bias effects from purely temperature-dependent effects due to overall heating of a device. Here we take advantage of a novel thermal biasing technique and demonstrate a nonlinear thermoelectric response in a quantum dot which is defined in a heterostructured semiconductor nanowire. We also show that a theoretical model based on the Master equations fully explains the observed nonlinear thermoelectric response given the energy-dependent transport properties of the quantum dot.

  15. From flint to stainless steel: observations on surgical instrument composition.

    PubMed Central

    Kirkup, J.

    1993-01-01

    Man's failure to extract deeply embedded thorns and arrowheads, with bare hands and teeth, stimulated 'instrument substitutes' mimicking these appendages. Evidence from primitive communities suggest animal, plant and mineral items were employed, both before and after metal became the standard material of today's armamentarium. Changing surgical instrument composition has mirrored concurrent technology and manufacturing methods both of which are reviewed. Particular significance is accorded flint, bronze, crucible steel, thermal sterilisation, nickel-plate, stainless steel and disposable plastics. The paper is based on an exhibition From Flint to Stainless Steel on display at the College. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 PMID:8215156

  16. Some Exact Solutions in Energy Dependent Transport Theory

    NASA Astrophysics Data System (ADS)

    Williams, M. M. R.

    1980-01-01

    Some exact solutions are obtained for energy dependent slowing down problems with energy dependent cross sections. The transport equation is solved using the backward-forward model of Fermi. Also studied is the energy dependent diffusion equation. Using these models, and a novel technique involving difference equations, it has been possible to find explicit, and numerically useful, solutions for slowing down from a plane, monoenergetic source in an infinite medium. The slowing down density and the energy deposition function are obtained which are of value in reactor physics and radiation damage calculations.

  17. AN INDEX OF COMPOSITIONAL DISSIMILARITY BETWEEN OBSERVED AND EXPECTED ASSEMBLAGES

    EPA Science Inventory

    The reference-condition approach to bioassessment often uses the observed/expected (O/E) ratio to indicate anthropogenic alteration of aquatic macroinvertebrates, fish, or periphyton assemblages. Given a list of taxa found at 1 or more minimally disturbed reference sites, E is t...

  18. Proton irradiation energy dependence of defect formation in graphene

    NASA Astrophysics Data System (ADS)

    Lee, Sanggeun; Seo, Jungmok; Hong, Juree; Park, Seul Hyun; Lee, Joo-Hee; Min, Byung-Wook; Lee, Taeyoon

    2015-07-01

    Graphene transistors on SiO2/Si were irradiated with 5, 10, and 15 MeV protons at a dose rate of 2 × 1014 cm-2. The effect of proton irradiation on the structural defects and electrical characteristics of graphene was measured using Raman spectroscopy and electrical measurements. Raman spectra exhibited high intensity peaks induced by defects after 5 and 10 MeV proton irradiation, whereas no significant defect-induced peaks were observed after 15 MeV proton irradiation. The drain current of graphene transistors decreased and the Dirac point shifted after proton irradiation; however, a flattening in the Dirac point occurred after 15 MeV proton irradiation. The variations in characteristics were attributed to different types of graphene defects, which were closely related to the irradiation energy dependency of the transferred energy. Our observation results were in good agreement with the Bethe formula as well as the stopping and range of ions in matter simulation results.

  19. Oxidation Embrittlement Observed in SiC/SiC Composites

    NASA Technical Reports Server (NTRS)

    Verrilli, Michael J.

    1997-01-01

    As part of a comprehensive materials characterization program at the NASA Lewis Research Center, tensile creep-rupture tests were performed on a SiC-fiber-reinforced SiC-matrix composite. The results of these tests and subsequent analysis revealed an oxidation embrittlement phenomena that occurs readily at a discreet temperature range below the maximum use temperature. The graph shows rupture lives for a creep stress of 83 MPa as a function of temperature. Note that the rupture time is constant at an intermediate temperature range of 700 to 982 C. This graph also shows the failure location, as measured from the center of the specimen. Whereas for temperatures of 500 to 700 C, failure occurred in the specimen gage section; at higher temperatures, the failure location migrated toward the cooled grip ends. Although the results initially suggested that the test procedure was influencing the measured creep rupture lives and driving the failure location out of the gage section, subsequent experiments and thermal stress analyses verified the robustness of the test method employed.

  20. NIMS Observes the Structure and Composition of Jupiter's Clouds

    NASA Technical Reports Server (NTRS)

    1997-01-01

    With the NIMS instrument high quality observations are being obtained from all parts of Jupiter. The images in the upper panel are taken at a wavelength of 4.8 microns. At this wavelength thermal radiation from about 100 km deep below the visible cloud deck is escaping, allowing us to study the deep atmospheric region.

    The overlying cloud deck absorbs a part of the radiation, but there are places where it is thin and more radiation can escape. These are called hot spot regions. Many hotspots regions occur in a zone between the equator and 15 degrees north latitude, the North Equatorial Belt (NEB), but thermal radiation is seen from much of the planet.

    The uniqueness of NIMS is that it is capable of observing the same spatial region at a maximum of 408 different wavelengths between 0.7 and 5.2 micron simultaneously. Every picture element (pixel) contains a spectrum of up to 408 wavelengths. The gases that compose the atmosphere leave there traces in the spectra. In this particular case, 48 wavelengths were available between 4.6 and 5.2 micron, and we see spectral signatures of water, ammonia, and phosphine. Also, the total amount of radiation is determined by the amount of overlying cloud, characterized by the cloud opacity. By means of model calculations, we can determine the amount of water and the cloud opacity for each individual spectrum. The amount ammonia and phosphine is more difficult to obtain because its influence on the spectra is weaker.

    The results of these calculations are shown in the form of maps in the next two panels. With NIMS, we can now have a detailed look at the spatial distribution of the water and ammonia amounts and the cloud opacity in the atmosphere. Not all the pixels from the observations have good spectra, so for some data points no reliable determination of the water and cloud opacity could be made.

    We find that the atmosphere is extremely dry in, and close to, the hot spot, with relative humidities between 0.02 % and 10

  1. Mineralogical indicators of Mercury's hollows composition in MESSENGER color observations

    NASA Astrophysics Data System (ADS)

    Vilas, Faith; Domingue, Deborah L.; Helbert, Jörn; D'Amore, Mario; Maturilli, Alessandro; Klima, Rachel L.; Stockstill-Cahill, Karen R.; Murchie, Scott L.; Izenberg, Noam R.; Blewett, David T.; Vaughan, William M.; Head, James W.

    2016-02-01

    Early during MErcury Surface Space ENvironment GEochemistry, and Ranging (MESSENGER)'s orbital mission, the Mercury Dual-Imaging System imaged the landform called hollows on the two craters Dominici and Hopper, using its Wide-Angle Camera with eight narrowband color filters ranging from 433 to 996 nm. An absorption feature centered in the MDIS 629 nm filter is evident in reflectance spectra for Dominici's south wall/rim hollows. A different absorption feature found in photometry of Dominici's center hollows extends through the MDIS 828 nm filter. Hollows in Hopper exhibit a weaker spectral absorption feature than that observed in Dominici's center. At Dominici, we postulate that fresher hollows-hosting material in the wall/rim was exposed to the space environment through a process of slumping of the overlying material. With time, local and global processes darken the hollows and change or mix the surface mineralogy, so that the spectral signature evolves. The hollows could contain low-density MgS and an opaque component, potentially derived from background material.

  2. Energy Dependence of Millisecond Timing Phenomena in the Z-Source GX 349+2

    NASA Astrophysics Data System (ADS)

    Michelson, Peter

    As part of a program to search for temporal signatures of Comptonizing clouds in Z sources, and other energy-dependent properties of high frequency phenomena, we are requesting an observation of GX 349+2 with high temporal and moderate spectral resolution. We will measure hard photon time lags and the X-ray variability coherence as a function of Z position. This observation, when combined with our previous observation of GX 340+0 and archival observations of the other Z sources, can constrain the geometries of scattering clouds in these systems, which are invoked to explain the spectral variations seen as well as the non- detection of coherent pulsations. These observations will also allow the study of the energy dependence of QPO as they evolve along the branches of the Z.

  3. Separable representation of energy-dependent optical potentials

    NASA Astrophysics Data System (ADS)

    Hlophe, L.; Elster, Ch.

    2016-03-01

    Background: One important ingredient for many applications of nuclear physics to astrophysics, nuclear energy, and stockpile stewardship are cross sections for reactions of neutrons with rare isotopes. Since direct measurements are often not feasible, indirect methods, e.g., (d ,p ) reactions, should be used. Those (d ,p ) reactions may be viewed as three-body reactions and described with Faddeev techniques. Purpose: Faddeev equations in momentum space have a long tradition of utilizing separable interactions in order to arrive at sets of coupled integral equations in one variable. Optical potentials representing the effective interactions in the neutron (proton) nucleus subsystem are usually non-Hermitian as well as energy dependent. Potential matrix elements as well as transition matrix elements calculated with them must fulfill the reciprocity theorem. The purpose of this paper is to introduce a separable, energy-dependent representation of complex, energy-dependent optical potentials that fulfill reciprocity exactly. Methods: Momentum space Lippmann-Schwinger integral equations are solved with standard techniques to obtain the form factors for the separable representation. Results: Starting from a separable, energy-independent representation of global optical potentials based on a generalization of the Ernst-Shakin-Thaler (EST) scheme, a further generalization is needed to take into account the energy dependence. Applications to n +48Ca ,n +208Pb , and p +208Pb are investigated for energies from 0 to 50 MeV with special emphasis on fulfilling reciprocity. Conclusions: We find that the energy-dependent separable representation of complex, energy-dependent phenomenological optical potentials fulfills reciprocity exactly. In addition, taking into account the explicit energy dependence slightly improves the description of the S matrix elements.

  4. Constraints on cosmological birefringence energy dependence from CMB polarization data

    SciTech Connect

    Gubitosi, G.; Paci, F. E-mail: fpaci@sissa.it

    2013-02-01

    We study the possibility of constraining the energy dependence of cosmological birefringence by using CMB polarization data. We consider four possible behaviors, characteristic of different theoretical scenarios: energy-independent birefringence motivated by Chern-Simons interactions of the electromagnetic field, linear energy dependence motivated by a 'Weyl' interaction of the electromagnetic field, quadratic energy dependence, motivated by quantum gravity modifications of low-energy electrodynamics, and inverse quadratic dependence, motivated by Faraday rotation generated by primordial magnetic fields. We constrain the parameters associated to each kind of dependence and use our results to give constraints on the models mentioned. We forecast the sensitivity that Planck data will be able to achieve in this respect.

  5. Observing the atmospheric composition with the IASI/MetOp satellite: emissions, composition and transport

    NASA Astrophysics Data System (ADS)

    Clerbaux, C.; Coheur, P.; George, M.; Clarisse, L.; Hurtmans, D.; Hadji-Lazaro, J.; Razavi, A.

    2010-12-01

    Among the available remote sensing data to monitor the atmospheric composition, IASI, the Infrared Atmospheric Sounding Interferometer flying onboard the MetOp satellite since 2006, offers unprecedented possibilities for sounding the troposphere in near-real time and for capturing sudden changes in the atmosphere with a global coverage. This presentation will review the capabilities of IASI to contribute to several aspects of atmospheric chemistry, such as the identification of local and regional sources to improve emission inventories, the tracking of long-range transport of pollution, and the detection of unexpected events such as large fires or volcanic plumes. Illustrations will be provided for carbon monoxide, methanol, ammonia, and ash/sulfur dioxide from volcanoes. The sensitivity and errors inherent to satellite sounding in the infrared spectral range will also be discussed.

  6. Energy dependence of relativistic electron flux variations in the outer radiation belt during geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Xiong, Ying; Xie, Lun; Li, Jinxing; Fu, Suiyan; Pu, Zuyin; Chen, Lunjin; Ni, Binbin; Li, Wen

    2015-04-01

    Geomagnetic storms can either increase or decrease relativistic electron fluxes in the outer radiation belt, depending on the delicate competition between electron energization and loss processes. Despite the well-known "energy independent" prototype in which electron fluxes enhance after geomagnetic storms at all energies, we present observations of "energy dependent" events, i.e., post-storm electron fluxes at lower energies (0.3-2.5 MeV, measured by MEPED/POES) recover or even exceed the pre-storm level, while electron fluxes at higher energies (2.5-14 MeV, measured by PET/SAMPEX) do not restore. The statistical survey of 84 isolated storms demonstrates that geomagnetic storms preferentially decrease relativistic electron fluxes at higher energies while flux enhancements are more common at lower energies: ~ 82% (3%) storm events produce increased (decreased) flux for 0.3-2.5 MeV electrons, while ~ 37% (45%) storms lead to enhancements (reductions) of 2.5-14 MeV electron flux. Superposed epoch analysis suggests that "energy dependent" events preferentially occur during periods of high solar wind density along with high dynamic pressure. Previous statistical studies have shown that this kind of solar wind conditions account for significant enhancements of EMIC waves, which cause efficient precipitation of > 2 MeV electrons into atmosphere via pitch angle scattering. Two cases of "energy dependent" events are investigated in detail with evident observations of EMIC waves that can resonate effectively with >2 MeV electrons. Besides, we do not capture much differences in the chorus wave activity between those "energy dependent" and "energy independent" events. Therefore, our results strongly suggest that EMIC waves play a crucial role in the occurrences of those "energy dependent" events in the outer zone during geomagnetic storms.

  7. Orientational photorefractive effects observed in poly(vinyl alcohol)/liquid crystal composites

    NASA Astrophysics Data System (ADS)

    Ono, Hiroshi; Saito, Isao; Kawatsuki, Nobuhiro

    1998-04-01

    We successfully observed orientational photorefractive gratings generated in poly(vinyl alcohol) (PVA)/liquid crystal (LC) composites doped with a fullerene (C60) as a photoconductive sensitizer under an applied dc field. Orientational photorefractivity was demonstrated by observing Raman-Nath diffraction beams with an external dc field. The photorefractive gratings were partially memorized even in the absence of the applied dc field.

  8. Hilda Asteroid Compositions as an Observational Test of Giant Planet Migration Models

    NASA Astrophysics Data System (ADS)

    Ryan, Erin L.; Woodward, Charles E.; Sharkey, Benjamin; Noll, Keith S.

    2015-11-01

    Multiple lines of evidence indicate that planetary migration is a key part of the evolution of planetary systems. Planetary migration models of the solar system suggest that the Jupiter Trojan and Hilda stable resonances were repopulated during giant planet migration. We have completed a 4-year, multi-epoch photomteric multi-color survey of Hilda asteroids in order to determine individual object composition. The colors of ~500 Hildas are now known, a factor of 3 increase in objects with determined compositions compared to the start of our observations. We report the results of our survey in the context of the predictions from current dynamical migration models, identify the model inconsistent with the compositional results, and address future observational data that is required in addition to Hilda asteroid compositions to validate the Nice and Grand Tack models.This work supported by the University of Minnesota Undergraduate Research Scholarship Program and NASA Planetary Astronomy Grant NNX13AJ11G.

  9. The energy dependence of the total charm cross section

    SciTech Connect

    Vogt, R

    2007-10-18

    We discuss the energy dependence of the total charm cross section and some of its theoretical uncertainties including the quark mass, scale choice and the parton densities. We compare the next-to-leading order calculation of the total cross section with results obtained using PYTHIA.

  10. Energy dependence of pion inelastic scattering from sup 208 Pb

    SciTech Connect

    Oakley, D.S. Lewis and Clark College, Portland, Oregon ); Peterson, R.J. ); Seestrom, S.J.; Morris, C.L.; Plum, M.A. ); Zumbro, J.D. ); Williams, A.L.; Bryan, M.A.; McDonald, J.W.; Moore, C.F. )

    1991-11-01

    Differential cross sections were measured for pion elastic and inelastic scattering from {sup 208}Pb at {ital T}{sub {pi}}=120 and 250 MeV. Energy-dependent neutron- and proton-transition matrix elements for a range of excited states were extracted and tested for consistency, using several structure models.

  11. Material identification based upon energy-dependent attenuation of neutrons

    DOEpatents

    Marleau, Peter

    2015-10-06

    Various technologies pertaining to identifying a material in a sample and imaging the sample are described herein. The material is identified by computing energy-dependent attenuation of neutrons that is caused by presence of the sample in travel paths of the neutrons. A mono-energetic neutron generator emits the neutron, which is downscattered in energy by a first detector unit. The neutron exits the first detector unit and is detected by a second detector unit subsequent to passing through the sample. Energy-dependent attenuation of neutrons passing through the sample is computed based upon a computed energy of the neutron, wherein such energy can be computed based upon 1) known positions of the neutron generator, the first detector unit, and the second detector unit; or 2) computed time of flight of neutrons between the first detector unit and the second detector unit.

  12. Normalization of energy-dependent gamma survey data.

    PubMed

    Whicker, Randy; Chambers, Douglas

    2015-05-01

    Instruments and methods for normalization of energy-dependent gamma radiation survey data to a less energy-dependent basis of measurement are evaluated based on relevant field data collected at 15 different sites across the western United States along with a site in Mongolia. Normalization performance is assessed relative to measurements with a high-pressure ionization chamber (HPIC) due to its "flat" energy response and accurate measurement of the true exposure rate from both cosmic and terrestrial radiation. While analytically ideal for normalization applications, cost and practicality disadvantages have increased demand for alternatives to the HPIC. Regression analysis on paired measurements between energy-dependent sodium iodide (NaI) scintillation detectors (5-cm by 5-cm crystal dimensions) and the HPIC revealed highly consistent relationships among sites not previously impacted by radiological contamination (natural sites). A resulting generalized data normalization factor based on the average sensitivity of NaI detectors to naturally occurring terrestrial radiation (0.56 nGy hHPIC per nGy hNaI), combined with the calculated site-specific estimate of cosmic radiation, produced reasonably accurate predictions of HPIC readings at natural sites. Normalization against two to potential alternative instruments (a tissue-equivalent plastic scintillator and energy-compensated NaI detector) did not perform better than the sensitivity adjustment approach at natural sites. Each approach produced unreliable estimates of HPIC readings at radiologically impacted sites, though normalization against the plastic scintillator or energy-compensated NaI detector can address incompatibilities between different energy-dependent instruments with respect to estimation of soil radionuclide levels. The appropriate data normalization method depends on the nature of the site, expected duration of the project, survey objectives, and considerations of cost and practicality. PMID:25811252

  13. Energy Dependence of Nuclear Suppression in the Fragmentation Region

    NASA Astrophysics Data System (ADS)

    Tywoniuk, Konrad; Arsene, Ionut; Bravina, Larissa; Zabrodin, Evgeny; Kaidalov, Alexei

    Energy dependence of nuclear shadowing and nuclear absorption is discussed in the framework of the Glauber-Gribov model and the AGK cutting rules. We calculate gluon shadowing using recent data on diffractive structure functions from HERA. Phenomenological implications for light particle production at SPS and RHIC are described and compared to charged particle production at mid- and forward rapidities. Comparison of the suppression at these energies leaves nevertheless little room for additional suppression phenomena.

  14. Measurements of the spectrum and energy dependence of X-ray transition radiation

    NASA Technical Reports Server (NTRS)

    Cherry, M. L.

    1978-01-01

    The results of experiments designed to test the theory of X-ray transition radiation and to verify the predicted dependence of the characteristic features of the radiation on the radiator dimensions are presented. The X-ray frequency spectrum produced by 5- to 9-GeV electrons over the range 4 to 30 keV was measured with a calibrated single-crystal Bragg spectrometer, and at frequencies up to 100 keV with an NaI scintillator. The interference pattern in the spectrum and the hardening of the radiation with increasing foil thickness are clearly observed. The energy dependence of the total transition-radiation intensity was studied using a radiator with large dimensions designed to yield energy-dependent signals at very high particle energies, up to E/mc-squared approximately equal to 100,000. The results are in good agreement with the theoretical predictions.

  15. Experimental observation of damage in 8HS fabric composites in tensile loading

    SciTech Connect

    Roy, A.K.

    1994-12-31

    An observation of damage in two different laminates (one symmetric and another unsymmetric) of 8HS fabric composites is made in tensile loading. The damage initiation seems to controlled by the state of local stress field, not by the ply stacking of the laminates. Further, the damage initiation occurred in the vicinity of yarn crimping.

  16. 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.

  17. Microstructural Observations in a Cast Al-Si-Cu/TiC Composite

    NASA Astrophysics Data System (ADS)

    Karantzalis, A. E.; Lekatou, A.; Georgatis, E.; Poulas, V.; Mavros, H.

    2010-06-01

    A 3-5 vol.% TiC particulate Al-Si-Cu composite was prepared by diluting Al/20 vol.% TiC composite in an Al-7Si-4Cu alloy matrix. TiC particle distribution consists of isolated and clustered particles which are both located at the primary-α grain boundaries and at the areas of the last solidified liquid. Particle pushing by the solidification front is responsible for the final particle location. The solidified microstructure consists of primary and intermetallic phases formed by a sequence of possible eutectic reactions. No evidence of TiC particle degradation was observed.

  18. Energy Dependent Responses of Relativistic Electron Fluxes in the Outer Radiation Belt to Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Xie, L.

    2015-12-01

    Geomagnetic storms can either increase 4 or decrease relativistic electron fluxes in the outer radiation belt. A statistical survey of 84 isolated storms demonstrates that geomagnetic storms preferentially decrease relativistic electron fluxes at higher energies while flux enhancements are more common at lower energies. In about 87% of the storms, 0.3-2.5 MeV electrons fluxes show increase, whereas 2.5-14 MeV electron fluxes increase in only 35% of the storms. Superposed epoch analyses suggest that such 'energy dependent' behavior of electrons preferably occurs during conditions of high solar wind density which is favorable to generate magnetospheric electromagnetic ion cyclotron (EMIC) waves and these 'energy dependent' events are associated with relatively weaker chorus activities. We have examined one of the cases where observed EMIC waves can resonate effectively with >2.5 MeV electrons and scatter them into the atmosphere. The correlation study further illustrates that electron flux drop-outs during storm main phases do not correlate well with the flux build-up during storm recovery phases. We suggest that a combination of efficient EMIC-induced scattering and weaker chorus-driven acceleration provide a viable candidate for the energy dependent responses of outer radiation belt relativistic electrons to geomagnetic storms. These results are of great interest to both understanding of the radiation belt dynamics and applications in space weather.

  19. SU-F-BRE-15: Verification of Energy Dependence of MAGAT Polymer Gel at Orthovoltage Energies

    SciTech Connect

    Roed, Y; Tailor, R; Ibbott, G; Pinsky, L

    2014-06-15

    Purpose: Investigation of dose response curves of methacrylic acid-based “MAGAT” gel at different effective energies to verify an energy dependence of polymer-gel dosimeters for orthovoltage energy x-rays. Methods: Six small cylindrical MAGAT gel phantoms were exposed to different dose levels; one phantom was unirradiated for background subtraction. This experiment was repeated for three different effective beam energies.24 h post irradiation the spin-spin relaxation times (T2) were measured with a 4.7 T Bruker MR scanner at 2 cm depth inside the gel. The T2 values were converted to relaxation rates (R2) and plotted against the respective dose levels corresponding to the different effective energies. The resulting dose response curves were compared for a 250 kVp beam, the 250 kVp beam filtered by 6 cm of water, and a 125 kVp beam. Results: The passage of the 250 kVp beam through water resulted in a half-value-layer (HVL) change from 1.05 mm Cu to 1.32 mm Cu at 6 cm depth with a change in effective energy from 81.3 keV to 89.5 keV, respectively. The dose response curves showed a shift to higher relaxation rates for the harder beam. The dose response measurements for the 125 kVp beam (HVL: 3.13 mm Al, effective energy: 33.9 keV) demonstrated even higher relaxation rates than for either of the other beams. Conclusion: The MAGAT dose response curves for three different effective energies demonstrate a complex energy dependence, with an apparent decrease in sensitivity at 89.5 keV effective energy. This energy dependence is consistent with observed discrepancies of depth dose data compared with ion-chamber data. For future investigations of larger volumes, an energy-dependent sensitivity function is needed to properly assess 3-dimensional dose distributions.

  20. HZEFRG1: An energy-dependent semiempirical nuclear fragmentation model

    SciTech Connect

    Townsend, L.W.; Wilson, J.W.; Tripathi, R.K.; Norbury, J.W.; Badavi, F.F.; Khan, F.

    1993-05-01

    Methods for calculating cross sections for the breakup of high-energy heavy ions by the combined nuclear and coulomb fields of the interacting nuclei are presented. The nuclear breakup contributions are estimated with an abrasion-ablation model of heavy ion fragmentation that includes an energy-dependent, mean free path. The electromagnetic dissociation contributions arising from the interacting coulomb fields are estimated by using Weizsacker-Williams theory extended to include electric dipole and electric quadrupole contributions. The complete computer code that implements the model is included as an appendix. Extensive comparisons of cross section predictions with available experimental data are made.

  1. HZEFRG1: An energy-dependent semiempirical nuclear fragmentation model

    NASA Technical Reports Server (NTRS)

    Townsend, Lawrence W.; Wilson, John W.; Tripathi, Ram K.; Norbury, John W.; Badavi, Francis F.; Khan, Ferdous

    1993-01-01

    Methods for calculating cross sections for the breakup of high-energy heavy ions by the combined nuclear and coulomb fields of the interacting nuclei are presented. The nuclear breakup contributions are estimated with an abrasion-ablation model of heavy ion fragmentation that includes an energy-dependent, mean free path. The electromagnetic dissociation contributions arising from the interacting coulomb fields are estimated by using Weizsacker-Williams theory extended to include electric dipole and electric quadrupole contributions. The complete computer code that implements the model is included as an appendix. Extensive comparisons of cross section predictions with available experimental data are made.

  2. Neutral composition gravity waves in the thermosphere observed by ESRO 4

    NASA Technical Reports Server (NTRS)

    Trinks, H.; Mayr, H. G.

    1975-01-01

    Neutral composition waves with a wave length of about 5000 km and a wave period of about 2.5 hours were observed by ESRO 4 in the altitude region of 250 km. The amplitudes are of the order of 25 percent for Ar, 15 percent for N2, and roughly 10 percent for He and O at 25 percent geographic latitude. The wave amplitudes are seen to decrease towards lower latitudes suggesting that the composition waves are launched by auroral sources. Simultaneous ground based ionosonde measurements of the F2 layer critical frequency at mid and low latitudes show a wave period consistent with the satellite observations. The theoretical investigation with a multi-component model shows that diffusion plays a major role in explaining these wave phenomena. The phase and amplitude relation between atmospheric constituents are sensitive to the altitude region in which energy is deposited thus suggesting that Joule heating or soft particle precipitation are the predominant energy sources.

  3. Composition of the Primary Crust of Mars: Observations of Deeply Excavated Crater Central Peaks

    NASA Astrophysics Data System (ADS)

    Skok, J. R.; Mustard, J. F.; Tornabene, L. L.; Murchie, S. L.

    2011-12-01

    It is predicted that the primary crust of Mars crystallized from a magma ocean and would be well preserved at depth on a single plate planet but poorly exposed as impacts, volcanism and alteration has reworked the upper crust. In a few select locations, extensive excavation by impact or erosion has exposed unaltered mafic minerals of the Martian crust. The majority of these exposures occur within the uplifted central peaks and peak rings of Southern Highland craters. We examine the mafic compositions of these deeply excavated crustal rocks in an attempt to constrain the composition of the Martian crust and test models of planetary formation. The search for deeply excavated bedrock from HiRISE images is ongoing and has so far resulted in nearly 200 potential locations. Over half of these currently have CRISM spectroscopic observations with ~50 locations having good exposures of crustal rocks showing little to no alteration. It is this combination of deeply excavated minerals that has potential to tap the preserved primary crust of Mars. We focus our analysis on olivine and pyroxene as crustal formation models predict that these two minerals would dominate the modal mineralogy of the crystallizing crust with a garnet layer potentially stable at depth. The high-resolution visible and near-infrared spectroscopic data provided by the CRISM instrument is ideally suited for examining these compositional characteristics. Initial in-depth analysis of the central peak of Alga Crater shows excellent exposures of lithologies characterized by both olivine and pyroxene. The olivine-bearing unit here has a fayalitic composition and a dunite lithology. This ancient Fe-rich olivine is in stark contrast to the Mg-enriched olivine of the primitive mantle of Earth. The primary pyroxene-bearing unit was determined to be a low-calcium, high-Fe enstatite orthopyroxenite, consistent with the mineralogy of the ancient Mars meteorite ALH84001. These observations suggest that the crust

  4. One year observation of water vapour isotopic composition at Ivittuut, Southern Greenland

    NASA Astrophysics Data System (ADS)

    Bonne, Jean-Louis; Masson-Delmotte, Valérie; Delmotte, Marc; Cattani, Olivier; Sodemann, Harald; Risi, Camille

    2013-04-01

    In September 2011, an automatic continuous water vapour isotopic composition monitoring instrument has been installed in the atmospheric station of Ivittuut (61.21° N, 48.17° W), southern Greenland. Precipitation has been regularly sampled on site at event to weekly scales and analysed in our laboratory for isotopic composition. Meteorological parameters (temperature, pressure, relative humidity, wind speed and direction) and atmospheric composition (CO2, CH4, Atmospheric Potential Oxygen) are also continuously monitored at Ivittuut. The meteorological context of our observation period will be assessed by comparison with the local climatology. The water vapour analyser is a Picarro Wavelength Scanned Cavity Ring-Down Spectrometer (WS-CRDS, model L2120i). It is automatically and regularly calibrated on the VSMOW scale using measurements of the isotopic composition of vaporized reference water standards using the Picarro Syringe Delivery Module (SDM). As measurements are sensitive to humidity level, an experimentally estimated calibration response function is used to correct our isotopic measurements. After data treatment, successive isotopic measurements of reference waters have a standard deviation of around 0.35 per mil for δ18O and 2.3 per mil for δD. Our instrumentation protocol and data quality control method will be presented, together with our one year δ18O, δD and d-excess measurements in water vapour and precipitation. The relationship between surface water vapour isotopic composition and precipitation isotopic composition will be investigated based on a distillation model. Specific difficulties linked to our low maintenance remote station will also be discussed. The processes responsible for the synoptic variability of Ivittuut water vapour isotopic composition will be investigated by comparing our observational dataset with (i) atmospheric back-trajectories and (ii) results from an isotopically-enabled atmospheric general circulation model (AGCM

  5. Crres observations of the composition of the ring-current ion populations

    SciTech Connect

    Roeder, J.L.; Fennell, J.F.; Chen, M.W.; Schulz, M.; Grande, M.

    1995-02-15

    The Magnetospheric Ion Composition Spectrometer onboard the CRRES spacecraft provided mass and charge state composition data for positive ions in the energy-per-charge range 10-425 keV/e. The CRRES data is compared to the AMPTE/CCE observations during both geomagnetically quiet and active periods. The CRRES average radial profiles of H+, He+, and He++ during quiet intervals are remarkably similar to those measured by CCE. The excess of ions measured by CRRES at L <4 compared to standard ion transport models tends to support the necessity of additional ion radial diffusion by ionospheric electric-field variations. A summary is also given of the measured storm-time variations of the major ion populations during the large storm of March 1991. The results are compared to previous observations by the AMPTE/CCE spacecraft during a large storm. The CRRES data confirm that the rapid initial recovery of the Dst magnetic index is due to a momentary change of the relative ion composition of the ring current to an oxygen-dominated state. A preliminary test of the Dessler-Parker-Sckopke relation between the ion energy and the global magnetic perturbation shows that the observed particle fluxes during the March 1991 storm could account for only 30-50% of the variation of the Dst magnetic index.

  6. 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.

  7. Some Physicochemical Phenomena Observed During Fabrication of Mg-C Cast Composites

    NASA Astrophysics Data System (ADS)

    Olszówka-Myalska, Anita

    2016-01-01

    Some effects acquired in composites processed under industrial conditions were presented. Glassy carbon particles (GCp) and short carbon fibers were applied in magnesium matrix composites fabricated by suspension casting. As the matrix magnesium alloys with Al and without Al but with Zn, Zr and rare earth elements (RE) were used. The main interest was focused on the behavior of the reinforcing components, depending on the magnesium alloying elements. The observation of the stirred suspensions during their industrial processing detected an effect of carbon components' migration to the top of the crucible, suggesting segregation processes. Experiments with unmixed suspensions performed by way of remelting the composites with uniformly distributed reinforcement showed that the segregation effect depends on the magnesium matrix composition. In the case of the alloy with Al, two zones with (top) and without reinforcement can be formed. For the alloys with Zn, Zr, and RE, an additional zone of segregated carbon reinforcement can appear directly at the bottom of the crucible. The SEM/EDS examination also showed some differences in the influence of the magnesium matrix on the carbon reinforcement dependent on the applied alloying elements. The most destructive effect was detected for the Al-containing alloy and minor defects in GCp were formed when Gd with Nd were applied.

  8. Energy Dependence of the Inverse Slope Parameter in Heavy-Ion Collisions

    NASA Astrophysics Data System (ADS)

    Hama, Y.; Grassi, F.; Socolowski, O., Jr.; Kodama, T.; Gazdzicki, M.; Gorenstein, M. I.

    2004-01-01

    We calculate, in a hydrodynamic approach, the mT spectra of kaons in central Pb+Pb (Au+Au) collisions, as function of energy. The experimentally observed anomalous behavior of the inverse slope parameter T* may be reproduced by a reasonable choice of the critical temperature Tc˜ 160 MeV at μ =0 and an equally reasonable choice of energy-dependent freeze-out temperature Tfo, thus supporting the argument that these data are an additional signature of deconfinement transition.

  9. The content and composition of meteoric smoke in mesospheric ice particles from SOFIE observations

    NASA Astrophysics Data System (ADS)

    Hervig, Mark E.; Deaver, Lance E.; Bardeen, Charles G.; Russell, James M.; Bailey, Scott M.; Gordley, Larry L.

    2012-08-01

    This work provides the first observational evidence that ice particles comprising polar mesospheric clouds (PMC) contain small amounts of meteoric smoke (0.01-3% by volume), using measurements from the Solar Occultation For Ice Experiment (SOFIE). PMC observations at wavelengths from the ultraviolet through the infrared are inconsistent with pure ice, but can be explained in terms of the extinction simulated for a mixture of ice and meteoric smoke. Simulations of ice-smoke mixtures considered 25 different smoke compositions. The PMC observations were consistent with smoke composed of carbon (C), wüstite (FeO), or magnesiowüstite (MgxFe1-xO, x=0.1-0.6), and inconsistent with the other compositions. A method was established for simultaneously retrieving PMC particle size and the volume fraction of smoke in ice using SOFIE observations at multiple wavelengths. Compared to assuming pure ice, SOFIE retrievals considering ice-smoke mixtures yield smaller ice radii (24%) and higher concentrations (137%).

  10. Energy dependence of normal branch oscillations in Scorpius X-1

    NASA Astrophysics Data System (ADS)

    Wang, J.; Chang, H.-K.; Liu, C.-Y.

    2012-11-01

    We report the energy dependence of normal branch oscillations (NBOs) in Scorpius X-1, a low-mass X-ray binary Z-source. Three characteristic quantities (centroid frequency, quality factor, and fractional root-mean-squared (rms) amplitude) of a quasi-periodic oscillation signal as functions of photon energy are investigated. We found that, although it is not yet statistically well established, there is a signature indicating that the NBO centroid frequency decreases with increasing photon energy when it is below 6-8 keV, which turns out to be positively correlated with the photon energy at the higher energy side. In addition, the rms amplitude increases significantly with the photon energy below 13 keV and then decreases in the energy band of 13-20 keV. There is no clear dependence on photon energy for the quality factor. Based on these results, we suggest that the NBO originates mainly in the transition layer.

  11. The energy dependence of refractory metals and alloys radiation damageability

    NASA Astrophysics Data System (ADS)

    Mukashev, K. M.; Umarov, F. F.

    2015-04-01

    In this work the systematical investigation of the radiation defects distribution profile energy dependence in three different materials - tantalum, molybdenum and 10X18H10T-VD stainless steel irradiated by high energy protons has been performed. It has been shown that in stainless steel and tantalum, independently of proton energy, the vacancy complexes related by configuration appear which are described by the slightly expressed elastic channel. The defects are recovered in one annealing stage with different migration activation energy. At the same time the molybdenum radiation damageability is composed of two components in each of which its specified defects formation mechanism takes action. For high energy protons the inelastic channel of interaction is the basic and subcascades appearance is created by primary knocked-on atoms of considerable energies. For low energy protons the processes of elastic interaction with lattice atoms and atomic hydrogen in the end of run creation are major.

  12. Organization and energy-dependent growth of microtubules in cells.

    PubMed Central

    Frankel, F R

    1976-01-01

    The organization and growth of microtubules in cultured mouse macrophages and fibroblasts were examined by indirect immunofluorescence microscopy with antibodies to microtubule protein. In macrophages, microtubules converged at a samll region at the cytocenter. During depolymerization, and repolymerization, this region acted as a microtubule organizing center. Microtubule growth was energy-dependent, but unaffected by dibutyryl-adenosine 3':5'-cyclic monophosphate, cholera toxin, or dibutyryl-guanosine 3':5'-cyclic monophosphate. Fibroblasts, which did not show such a simple microtubule organization as macrophages, contained mainly one or two, but occasionally as many as four, organizing centers during repolymerization. These microtubule organizing centers often appeared as fluorescent rings with a dark center. Images PMID:785472

  13. Energy-dependent effects of resveratrol in Saccharomyces cerevisiae.

    PubMed

    Madrigal-Perez, Luis Alberto; Canizal-Garcia, Melina; González-Hernández, Juan Carlos; Reynoso-Camacho, Rosalia; Nava, Gerardo M; Ramos-Gomez, Minerva

    2016-06-01

    The metabolic effects induced by resveratrol have been associated mainly with the consumption of high-calorie diets; however, its effects with standard or low-calorie diets remain unclear. To better understand the interactions between resveratrol and cellular energy levels, we used Saccharomyces cerevisiae as a model. Herein it is shown that resveratrol: (a) decreased cell viability in an energy-dependent manner; (b) lessening of cell viability occurred specifically when cells were under cellular respiration; and (c) inhibition of oxygen consumption in state 4 occurred at low and standard energy levels, whereas at high energy levels oxygen consumption was promoted. These findings indicate that the effects of resveratrol are dependent on the cellular energy status and linked to metabolic respiration. Importantly, our study also revealed that S. cerevisiae is a suitable and useful model to elucidate the molecular targets of resveratrol under different nutritional statuses. Copyright © 2016 John Wiley & Sons, Ltd. PMID:26945517

  14. Measurement of energy dependence for XRCT radiochromic film

    SciTech Connect

    Butson, Martin J.; Cheung, Tsang; Yu, Peter K. N.

    2006-08-15

    Gafchromic XRCT, radiochromic film is assessed over a broad energy range, from kilovoltage to megavoltage x rays for variations in reflected optical density to dose response. A large energy dependence was found with reflected optical density output for the same delivered dose varying from 7.8{+-}0.35 at 25.5 keV (50 kVp) peaking at 12.1{+-}0.5 at 54 keV (125 kVp) to 0.975{+-}0.03 at 2300 keV (10 MV) when normalized to 1 at 1400 keV (6 MV) energy. The response is constant (within 3%) in the 36-69 keV equivalent photon energy range, which corresponds to x-ray tube generating potentials of approximately 100-150 kVp. This matches well with beam qualities for diagnostic computed topography applications.

  15. Observations of systematic temporal evolution in elemental composition during gradual solar energetic particle events

    NASA Astrophysics Data System (ADS)

    Tylka, Allan J.; Reames, Donald V.; Ng, Chee K.

    The WIND/EPACT experiment offers a ˜100 fold increase in collecting power over instruments flown in previous solar cycles, thus allowing unprecedented detailed studies of temporal evolution in gradual solar energetic particle (SEP) events. We present hourly WIND/EPACT observations at ˜2-10 MeV/nuc from the 20 April 1998 and 26 August 1998 SEP events. These observations show striking patterns in elemental composition which evolve in a systematic fashion throughout the events' several-day durations. These data, combined with theoretical modeling in a companion Letter [Ng et al. 1999], suggest that a dynamic Alfvén wave field, generated primarily by streaming energetic protons, is responsible for the complex behavior which is observed.

  16. Outer-core compositional stratification from observed core wave speed profiles.

    PubMed

    Helffrich, George; Kaneshima, Satoshi

    2010-12-01

    Light elements must be present in the nearly pure iron core of the Earth to match the remotely observed properties of the outer and inner cores. Crystallization of the inner core excludes light elements from the solid, concentrating them in liquid near the inner-core boundary that potentially rises and collects at the top of the core, and this may have a seismically observable signal. Here we present array-based observations of seismic waves sensitive to this part of the core whose wave speeds require there to be radial compositional variation in the topmost 300 km of the outer core. The velocity profile significantly departs from that of compression of a homogeneous liquid. Total light-element enrichment is up to five weight per cent at the top of the core if modelled in the Fe-O-S system. The stratification suggests the existence of a subadiabatic temperature gradient at the top of the outer core. PMID:21150995

  17. The Influence of Solar Extreme Ultraviolet Radiation on Ring Current Ion Composition: Polar and CRRES Observations

    NASA Astrophysics Data System (ADS)

    Roeder, J. L.; Fennell, J. F.; Pulkkinen, T. I.; Turner, N. E.; Grande, M.

    2001-05-01

    The ion composition observations by the Polar spacecraft from the last solar minimum to the present are compared to similar observations by CRRES in the previous cycle. The Magnetospheric Ion Composition Spectrometer (MICS) was onboard CRRES and is part of the Polar CAMMICE experiment. The MICS sensor provided mass and charge state composition data for the energetic (1-425 keV/q) ions including H+, He+, He++, and O+. The 5-minute average number densities for each species are computed by mapping the MICS fluxes down to the magnetic equator using the measured pitch angle distributions and integrating the equatorial spectrum over the energy range 1-200 keV/q. Approximately 3.5 years of the Polar mission in the rising part of the solar cycle are used for the database. The densities are analyzed statistically with the solar EUV index F10.7 and various geomagnetic indices such as Kp and Dst. The results are compared with a similar study of the ion composition in the energy range 0.9-15.9 keV/q measured by the GEOS 2 satellite during geomagnetically quiet periods [Young et al., 1982], and with the recent survey of the relative composition measured by Polar averaged over all times [Pulkkinen et al., 2000]. It is found that ion densities at L ~ 6-7 during relatively quiet intervals show correlations to the EUV and geomagnetic activity similar to the results of Young et al. [1992]. At lower L the correlation of the ion density with the EUV and activity levels increases substantially, due in part to the extremely low energetic ion densities during the quiet intervals of solar minimum. This may be interpreted as a combination of the solar cycle effects on 1) the ring current source population; and 2) the processes which transport the ions to lower L. The behavior of the ion composition during geomagnetic stormtime is also investigated by restricting the density database to those intervals with the Dst index below a threshold value. Paradoxically, the Polar data shows that the

  18. 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

  19. 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

  20. Simulation of energy-dependent electron diffusion processes in the Earth's outer radiation belt

    NASA Astrophysics Data System (ADS)

    Ma, Q.; Li, W.; Thorne, R. M.; Nishimura, Y.; Zhang, X.-J.; Reeves, G. D.; Kletzing, C. A.; Kurth, W. S.; Hospodarsky, G. B.; Henderson, M. G.; Spence, H. E.; Baker, D. N.; Blake, J. B.; Fennell, J. F.; Angelopoulos, V.

    2016-05-01

    The radial and local diffusion processes induced by various plasma waves govern the highly energetic electron dynamics in the Earth's radiation belts, causing distinct characteristics in electron distributions at various energies. In this study, we present our simulation results of the energetic electron evolution during a geomagnetic storm using the University of California, Los Angeles 3-D diffusion code. Following the plasma sheet electron injections, the electrons at different energy bands detected by the Magnetic Electron Ion Spectrometer (MagEIS) and Relativistic Electron Proton Telescope (REPT) instruments on board the Van Allen Probes exhibit a rapid enhancement followed by a slow diffusive movement in differential energy fluxes, and the radial extent to which electrons can penetrate into depends on energy with closer penetration toward the Earth at lower energies than higher energies. We incorporate radial diffusion, local acceleration, and loss processes due to whistler mode wave observations to perform a 3-D diffusion simulation. Our simulation results demonstrate that chorus waves cause electron flux increase by more than 1 order of magnitude during the first 18 h, and the subsequent radial extents of the energetic electrons during the storm recovery phase are determined by the coupled radial diffusion and the pitch angle scattering by EMIC waves and plasmaspheric hiss. The radial diffusion caused by ULF waves and local plasma wave scattering are energy dependent, which lead to the observed electron flux variations with energy dependences. This study suggests that plasma wave distributions in the inner magnetosphere are crucial for the energy-dependent intrusions of several hundred keV to several MeV electrons.

  1. Observation of Surface Composition during ECR Discharge Cleaning in JFT-2M

    NASA Astrophysics Data System (ADS)

    Matsuzaki, Yoshimi; Ohtsuka, Hideo

    1986-03-01

    Surface composition on a molybdenum sample has been observed during ECR discharge cleaning (ECR-DC) by Auger electron spectroscopy in JFT-2M. ECR-DC reduces oxygen levels to one-thrid of those before exposure within thirty minutes, and the molybdenum concentration increases up to a factor of three during ECR-DC. Carbon levels decrease once, then increase gradually. In the later phase Auger line shapes are similar to pure carbon. Sulfur, which appears under 120°C baking, surfaces from the stainless steel of the chamber as a result of the baking, and is sputtered by plasmas and deposited on the sample.

  2. Comparison of Martian magnetic pileup boundary with ion composition boundary observed by MAVEN

    NASA Astrophysics Data System (ADS)

    Matsunaga, K.; Seki, K.; Brain, D. A.; Hara, T.; Masunaga, K.; McFadden, J. P.; Halekas, J. S.; Mitchell, D. L.; Mazelle, C. X.; Connerney, J. E. P.; Jakosky, B. M.

    2015-12-01

    Martian upper atmosphere directly interacts with the solar wind, since Mars does not possess the intrinsic global magnetic field. This interaction forms a transition region between the shocked solar wind (magnetosheath) and the ionosphere, in which characteristic boundary structures are embedded. Previous studies have shown existence of the induced magnetosphere or magnetic pileup region in the transition region. Mars Global Surveyor (MGS) observed the magnetic pileup boundary (MPB), a boundary between the magnetosheath and the magnetic pileup region by its magnetometer and electron reflectometer [e.g., Vignes et al., 2000, Trotignon et al., 2006]. On one hand, Phobos 2 and Mars Express (MEX) observed the ion composition boundary (ICB) by their ion mass analyzer [e.g., Breus et al., 1991, Dubinin et al., 2006], where the ion composition changes from the solar wind origin to planetary origin dominant. Due to the lack of continuous simultaneous observations of the magnetic field and ion composition, however, relations between MPB and ICB are far from understood. In this study, we investigate relative locations and characteristics of MPB and ICB and their dependence on solar wind parameters, utilizing a full package of plasma instruments onboard Mars Atmosphere and Volatile EvolutioN (MAVEN). We conducted a statistical analysis of the ion, electron, and magnetic field data obtained by MAVEN from November 2014 to March 2015 in order to investigate relations between MPB and ICB. We identified MPB from the electron and magnetic field data by inspection based on Trotignon et al. [2006]. We calculated the density ratio between the planetary heavy ions and the solar wind protons to investigate the ion composition around MPB. Results show that there is a north-south asymmetry in locations of MPB and ICB. Observations also indicate that the relative location of MPB and ICB has deference between dayside and nightside. The MPB locations also depend on the solar wind parameters

  3. Quenched carbonaceous composite - Fluorescence spectrum compared to the extended red emission observed in reflection nebulae

    NASA Technical Reports Server (NTRS)

    Sakata, Akira; Wada, Setsuko; Narisawa, Takatoshi; Asano, Yoichi; Iijima, Yutaka; Onaka, Takashi; Tokunaga, Alan T.

    1992-01-01

    The photoluminescence (fluorescence) of a film of the laboratory-synthesized quenched carbonaceous composite (filmy QCC) is shown to have a single broad emission feature with a peak wavelength that varies from 670 to 725 nm, and coincides with that of the extended red emission observed in reflection nebulae. The rapid decay of the filmy QCC red fluorescence in air and of the stable blue fluorescence of the filmy QCC dissolved in liquid Freon suggests that the red fluorescence originates from the interaction of active chemical species and aromatic components in the filmy QCC. A material similar in nature to that of the filmy QCC may be a major component of interstellar dust.

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

    This work updates and expands on results of our long-term radar-driven observational campaign of 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 (Ockert-Bell, M.E., Clark, B.E., Shepard, M.K., Rivkin, A.S., Binzel, R.P., Thomas, C.A., DeMeo, F.E., Bus, S.J., Shah, S. [2008]. Icarus 195, 206-219; Ockert-Bell, M.E., Clark, B.E., Shepard, M.K., Issacs, R.A., Cloutis, E.A., Fornasier, S., Bus, S.J. [2010]. Icarus 210, 674-692; Shepard, M.K. et al. [2008a]. Icarus 193, 20-38; Shepard, M.K. et al. [2008b]. Icarus 195, 184-205; Shepard, M.K. et al. [2010]. Icarus 215, 547-551). Eighteen of our targets were near-simultaneously observed with radar and those observations are described in Shepard et al. (Shepard, M.K. et al. [2010]. Icarus 215, 547-551). We combine our near-infrared data with available visible wavelength data for a more complete compositional analysis of our targets. Compositional evidence is derived from our target asteroid spectra using two different methods, a χ2 search for spectral matches in the RELAB database and parametric comparisons with meteorites. We present four new methods of parametric comparison, including discriminant analysis. Discriminant analysis identifies meteorite type with 85% accuracy. This paper synthesizes the results of these two analog search algorithms and reconciles those results with analogs suggested from radar data (Shepard, M.K. et al. [2010]. Icarus 215, 547-551). We have observed 29 asteroids, 18 in conjunction with radar observations. For eighteen out of twenty-nine objects observed (62%) our compositional predictions are consistent over two or more methods applied. We find that for our Xc and Xk targets the best fit is an iron meteorite for 34% of the samples. Enstatite chondrites were best fits for 6 of our targets (21%). Stony-iron meteorites were best fits for 2 of our targets (7%). A discriminant

  5. Cosmic Origins Spectrograph Observations of the Chemical Composition of LMC N132D

    NASA Astrophysics Data System (ADS)

    Beasley, Matthew N.; France, K.; Green, J.; Keeney, B.; Danforth, C.; Froning, C.

    2010-01-01

    We present new far-ultraviolet spectra of an oxygen-rich knot in the Large Magellanic Cloud supernova remnant N132D, obtained with the Hubble Space Telescope/Cosmic Origins Spectrograph. Moderate resolution (v 200 km/s) spectra in the HST far-ultraviolet bandpass (1150 - 1750 A) show emission from several ionization states of oxygen as well as trace amounts of other species. We use the improvements in sensitivity and resolving power offered by COS to separate contributions from different velocity components within the remnant, as well as emission from different species within the oxygen-rich knot itself. This is the first time that compositional and velocity structure in the ultraviolet emission lines from N132D has been resolved, and we use this to assess the chemical composition of the remnant. No nitrogen is detected in N132D and multiple carbon species are found at velocities inconsistent with the main oxygen component. We find helium and silicon to be associated with the oxygen-rich knot, and use the reddening-corrected line strengths of OIII], OIV], OV, and SiIV to constrain the composition and physical characteristics of this oxygen-rich knot. We find that models with a silicon-to-oxygen abundance ratio of N(Si)/N(O) = 0.01 can reproduce the observed emission for a shock velocity of 130 km/s, implying a mass of 50 solar masses for the N132D progenitor star.

  6. Dynamical thresholds and quantum undulations in the energy dependence of rotationally inelastic integral cross sections

    SciTech Connect

    Schinke, R.

    1981-12-01

    We report the observation of distinct structures in the energy dependence of rotationally inelastic integral cross sections for the systems He--Na/sub 2/ and Ne--Na/sub 2/. The calculations are performed within the infinite-order-sudden and the coupled states approximation using accurate ab initio potential energy surfaces. The integral cross section for a 0..-->..j' transition typically rises steeply at low energies, reaches a maximum, and declines slowly to the high energy region showing more or less pronounced quantum undulations. The onset of the cross section is determined by dynamical constraints rather than energy conservation. All structures in the integral cross sections are explained in terms of the energy dependence of rotational rainbow features in the corresponding differential cross sections. In particular, the undulations at higher energies stem from the supernumerary rotational rainbows. In this sense they are interpreted as analogous to the glory maxima in the elastic integral cross section for scattering from isotropic potentials. The observed structures are sensitive to the anisotropy of the repulsive branch of the potential energy surface.

  7. Solar wind observations with the ion composition instrument aboard the ISEE-3 ICE spacecraft

    NASA Technical Reports Server (NTRS)

    Ogilvie, K. W.; Coplan, M. A.; Bochsler, P.; Geiss, J.

    1989-01-01

    The principal observations obtained by the Ion Composition Instrument (ICI) flown on the ISEE-3/ICE spacecraft, which was in the solar wind from September 1978 to the end of 1982, before being directed to the far magnetotail of the Earth are discussed. Almost continuous observations were made of the abundances of 3He++, 4He++, O6+, O7+, Ne, Si and Fe in various charge states, and of their bulk speeds and temperatures. The results show that there is a strong tendency in the collisionless solar wind for the ionic temperatures to be proportional to the masses. For heavier ions these temperatures exceed typical coronal electron temperatures. 4He++, especially in high speed streams, moves faster than H+, and travels at the same speed as heavier ions. The mechanism leading to this heating and rapid streaming is still not entirely clear.

  8. The Wmo Global Atmosphere Watch Programme: Global Framework for Atmospheric Composition Observations and Analysis

    NASA Astrophysics Data System (ADS)

    Tarasova, O. A.; Jalkanen, L.

    2010-12-01

    The WMO Global Atmosphere Watch (GAW) Programme is the only existing long-term international global programme providing an international coordinated framework for observations and analysis of the chemical composition of the atmosphere. GAW is a partnership involving contributors from about 80 countries. It includes a coordinated global network of observing stations along with supporting facilities (Central Facilities) and expert groups (Scientific Advisory Groups, SAGs and Expert Teams, ETs). Currently GAW coordinates activities and data from 27 Global Stations and a substantial number of Regional and Contributing Stations. Station information is available through the GAW Station Information System GAWSIS (http://gaw.empa.ch/gawsis/). There are six key groups of variables which are addressed by the GAW Programme, namely: ozone, reactive gases, greenhouse gases, aerosols, UV radiation and precipitation chemistry. GAW works to implement integrated observations unifying measurements from different platforms (ground based in situ and remote, balloons, aircraft and satellite) supported by modeling activities. GAW provides data for ozone assessments, Greenhouse Gas Bulletins, Ozone Bulletins and precipitation chemistry assessments published on a regular basis and for early warnings of changes in the chemical composition and related physical characteristics of the atmosphere. To ensure that observations can be used for global assessments, the GAW Programme has developed a Quality Assurance system. Five types of Central Facilities dedicated to the six groups of measurement variables are operated by WMO Members and form the basis of quality assurance and data archiving for the GAW global monitoring network. They include Central Calibration Laboratories (CCLs) that host primary standards (PS), Quality Assurance/Science Activity Centres (QA/SACs), World Calibration Centers (WCCs), Regional Calibration Centers (RCCs), and World Data Centers (WDCs) with responsibility for

  9. COMPOSITION STRUCTURE OF INTERPLANETARY CORONAL MASS EJECTIONS FROM MULTISPACECRAFT OBSERVATIONS, MODELING, AND COMPARISON WITH NUMERICAL SIMULATIONS

    SciTech Connect

    Reinard, Alysha A.; Mulligan, Tamitha E-mail: blynch@ssl.berkeley.edu

    2012-12-20

    We present an analysis of the ionic composition of iron for two interplanetary coronal mass ejections (ICMEs) observed on 2007 May 21-23 by the ACE and STEREO spacecraft in the context of the magnetic structure of the ejecta flux rope, sheath region, and surrounding solar wind flow. This analysis is made possible due to recent advances in multispacecraft data interpolation, reconstruction, and visualization as well as results from recent modeling of ionic charge states in MHD simulations of magnetic breakout and flux cancellation coronal mass ejection (CME) initiation. We use these advances to interpret specific features of the ICME plasma composition resulting from the magnetic topology and evolution of the CME. We find that, in both the data and our MHD simulations, the flux ropes centers are relatively cool, while charge state enhancements surround and trail the flux ropes. The magnetic orientations of the ICMEs are suggestive of magnetic breakout-like reconnection during the eruption process, which could explain the spatial location of the observed iron enhancements just outside the traditional flux rope magnetic signatures and between the two ICMEs. Detailed comparisons between the simulations and data were more complicated, but a sharp increase in high iron charge states in the ACE and STEREO-A data during the second flux rope corresponds well to similar features in the flux cancellation results. We discuss the prospects of this integrated in situ data analysis and modeling approach to advancing our understanding of the unified CME-to-ICME evolution.

  10. Observation of atomic scale compositional and displacive modulations in incommensurate melilite electrolytes

    SciTech Connect

    Wei, Fengxia; Williams, Tim; An, Tao; Baikie, Tom; Kloc, Christian; Wei, Jun; White, Tim

    2013-07-15

    The paradigm that functional materials are adequately described as three-dimensional crystal structures is not universally tenable. Gallate melilites are efficient oxide ion conductors at intermediate temperatures (∼750 °C) with non-rational crystallographic modulations presumed to play a key role in significantly enhancing oxygen mobility. Lattice distortions associated with incommensuration are usually extrapolated from diffraction analysis of volumes greatly exceeding the scale of modulation. Therefore, opportunities for making direct nanometric measurements are exceptionally valuable for correlating structure with function. In [CaLn]{sub 2}[Ga]{sub 2}[Ga{sub 2}O{sub 7}]{sub 2} (Ln=Nd, La) melilites, atomic displacive and compositional modulation waves can be imaged by high angle annular dark field and bright field scanning transmission electron microscopy with contrast quantified through electron scattering simulation. Here, we present atomic scale observations of (3+2)-dimensional modulations in gallate melilites which expands our understanding of the ion conduction mechanism and provides guidance for enhancing the performance of solid oxide fuel cells through crystal chemical tailoring. - Highlights: • Characterise the (3+2)-dimensional melilite electrolytes using STEM technique. • Direct observation on displacive and compositional modulation in melilites. • Structural flexibility reduces when increasing interstitial oxygen. • Domain-like incommensurate modulation model is proposed.

  11. Pulse energy dependence of subcellular dissection by femtosecond laser pulses

    NASA Technical Reports Server (NTRS)

    Heisterkamp, A.; Maxwell, I. Z.; Mazur, E.; Underwood, J. M.; Nickerson, J. A.; Kumar, S.; Ingber, D. E.

    2005-01-01

    Precise dissection of cells with ultrashort laser pulses requires a clear understanding of how the onset and extent of ablation (i.e., the removal of material) depends on pulse energy. We carried out a systematic study of the energy dependence of the plasma-mediated ablation of fluorescently-labeled subcellular structures in the cytoskeleton and nuclei of fixed endothelial cells using femtosecond, near-infrared laser pulses focused through a high-numerical aperture objective lens (1.4 NA). We find that the energy threshold for photobleaching lies between 0.9 and 1.7 nJ. By comparing the changes in fluorescence with the actual material loss determined by electron microscopy, we find that the threshold for true material ablation is about 20% higher than the photobleaching threshold. This information makes it possible to use the fluorescence to determine the onset of true material ablation without resorting to electron microscopy. We confirm the precision of this technique by severing a single microtubule without disrupting the neighboring microtubules, less than 1 micrometer away. c2005 Optical Society of America.

  12. Energy-Dependent Fission Q Values Generalized for All Actinides

    SciTech Connect

    Vogt, R

    2008-09-25

    We generalize Madland's parameterization of the energy release in fission to obtain the dependence of the fission Q values on incident neutron energy, E{sub n}, for all major and minor actinides. These Q(E{sub n}) parameterizations are included in the ENDL2008 release. This paper describes calculations of energy-dependent fission Q values based on parameterizations of the prompt energy release in fission [1], developed by Madland [1] to describe the prompt energy release in neutron-induced fission of {sup 235}U, {sup 238}U, and {sup 239}Pu. The energy release is then related to the energy deposited during fission so that experimentally measurable quantities can be used to obtain the Q values. A discussion of these specific parameterizations and their implementation in the processing code for Monte Carlo neutron transport, MCFGEN, [2] is described in Ref. [3]. We extend this model to describe Q(E) for all actinides, major and minor, in the Evaluated Nuclear Data Library (ENDL) 2008 release, ENDL2008.

  13. Energy Dependent DVCS Cross Sections from JLab Hall A

    NASA Astrophysics Data System (ADS)

    Hyde, Charles; JLab Hall A Collaboration

    2013-10-01

    In 2010, in experiments E07-007 (hydrogen target) and E08-025 (deuterium target), the Jefferson Lab Hall A collaboration measured the helicity-dependent and helicity-independent cross sections at fixed xB = 0 . 36 , at Q2 = 1 . 5 , 1 . 75 , and 2 . 0 GeV2, and at two beam energies, 4.45 and 5.55 GeV. We detected the scattered electron in the Hall A High Resolution Spectrometer (HRS-L), and the coincidence photon in an upgraded 208 element PbF2 calorimeter. Exclusivity is inferred by missing mass in the (e ,e' γ) X reaction. In the unpolarized cross sections, the | DVCS | 2 and ℜe [DVCS† BH ] terms have different kinematic dependencies on the incident beam energy. I present preliminary results on the energy-dependence of the cross sections, and discuss their sensitivity to the Generalized Parton Distributions (GPDs). US DOE, NSF, and French IN2P3 and ANR.

  14. Energy Dependent Bias in the Weighted Point Model.

    SciTech Connect

    Santi, P. A.; Geist, W. H.

    2005-01-01

    While the weighted point multiplicity model has successfully reduced the bias that is associated with variable multiplication of neutrons within a sample (which was assumed constant in the standard point multiplicity model), other potential sources of bias still exists within the weighted point model. One significant source of bias arises from the assumption that the energies of the neutrons from ({alpha},n) reactions on impurities in the sample have the same average energy as neutrons emitted from the spontaneous fission of {sup 240}Pu. An investigation into the effects that neutron energy has on the assay results (effective {sup 240}Pu mass, alpha, and multiplication) of the weighted point multiplicity model has been performed using MCNPX, Version 2.5f for impure plutonium metal samples in a number of different detector systems. The effects of energy dependence of the detection efficiency and gate fractions on the assay results, as well as the measured singles, doubles, and triples rates were also studied. Methods for mitigating the effects of neutron energy on the weighted-point multiplicity model results will be presented and discussed.

  15. Light Scattering and Compositional Analysis of Saturn's Rings Using Cassini UVIS Spectral Observations

    NASA Astrophysics Data System (ADS)

    Bradley, E. T.; Colwell, J. E.; Esposito, L. W.

    2015-12-01

    Saturn's ring particles are roughly centimeter to several-meter-sized objects that are covered with a regolith of icy grains. In general the composition of the regolith of an object can be investigated by comparing photometric models to reflectance spectra of the surface. However, since the rings as a whole are not a solid surface and the A and B ring particles clump together into self-gravity wakes, the light scattering behavior of the rings has a complex dependence on the geometry of the observations. In order to deal with this we first determine the ring particle albedo for the A, B, and C rings and the Cassini Division at discrete far ultraviolet wavelengths across the water ice absorption edge at 165 nm. We next use the retrieved albedos to compare to spectral models that use available optical constants in the FUV for water ice and various plausible non-water-ice contaminants such as organic tholins, silicates, and other ices.. We retrieve the ring particle albedo by comparing observations of the lit face of the rings to a single scattering Chandrasekhar model. We then compare the observations to photometric models where we assume that the non-water-ice constituents are either embedded in water ice grains so that the effective optical constants are a linear combination of constituent optical constants or that the regolith consists of discrete grains of water ice and non-ice constituents. We find that the best fit of the compositional models to the ring particle albedo is for water ice abundances greater than 95% and water ice grain sizes of a few microns.

  16. Sub-barrier fusion excitation function data and energy dependent Woods-Saxon potential

    NASA Astrophysics Data System (ADS)

    Gautam, Manjeet Singh

    2016-07-01

    This paper analyzed the role of intrinsic degrees of freedom of colliding nuclei in the enhancement of sub-barrier fusion cross-section data of various heavy ion fusion reactions. The influences of inelastic surface vibrations of colliding pairs are found to be dominant and their couplings result in the significantly larger fusion enhancement over the predictions of the one dimensional barrier penetration model at sub-barrier energies. The theoretical calculations are performed by using energy dependent Woods-Saxon potential model (EDWSP model) in conjunction with the one dimensional Wong formula. The effects of dominant intrinsic channels are entertained within framework of the coupled channel calculations obtained by using the code CCFULL. It is quite interesting to note that the energy dependence in Woods-Saxon potential simulates the effects of inelastic surface vibrational states of reactants wherein significantly larger value of diffuseness parameter ranging from a = 0.85 fm to a = 0.95 fm is required to address the observed fusion excitation function data of the various heavy ion fusion reactions.

  17. ENERGY-DEPENDENT TIME LAGS IN THE SEYFERT 1 GALAXY NGC 4593

    SciTech Connect

    Sriram, K.; Agrawal, V. K.; Rao, A. R.

    2009-08-01

    We investigate the energy-time lag dependence of the source NGC 4593 using XMM-Newton/EPIC pn data. We found that the time lag dependency is linear in nature with respect to the logarithm of different energy bands. We also investigate the frequency-dependent time lags and identify that at some frequency range (5 x 10{sup -5} Hz to 2 x 10{sup -4} Hz) the X-ray emission is highly coherent, mildly frequency dependent, and very strongly energy dependent. These observations can be explained in the framework of the thermal Comptonization process, and they indicate a truncated accretion disk very close to the black hole. We discuss the plausible spectral state to explain the phenomenon and conclude that the observed properties bear a close resemblance to the intermediate state or the steep power-law state, found in galactic black hole sources.

  18. Energy-dependent effects of scattering atmospheres on X-ray pulsar pulse profiles

    NASA Technical Reports Server (NTRS)

    Sturner, Steven J.; Dermer, Charles D.

    1994-01-01

    We propose that radiation-supported scattering atmospheres near accreting X-ray pulsars (XRPs) can explain energy-dependent features observed in the pulse profiles of 4U 1626-67, 4U 1538-52, 4U 1907+09 and Vela X-1. These atmospheres provide a physical model for the phenomenological annular emitting regions employed by Leahy to fit X-ray pulsar pulse profiles. We examine the effects of the scattering atmospheres under the assumptions that stable, optically thick atmospheres exist in a region where the optically thin resonant radiation force exceeds the force of gravity on ionized hydrogen. We predict that less complex pulse profiles will be observed at higher photon energies because the scattering atmospheres, which are supported by resonant Compton radiation pressure, become transparent to photons with energies greater than the cyclotron energy at the neutron star surface.

  19. Direct observations of the influence of solution composition on magnesite dissolution

    NASA Astrophysics Data System (ADS)

    King, Helen E.; Putnis, Christine V.

    2013-05-01

    In situ observations during atomic force microscopy experiments and ex situ observations after static and flow-through experiments were used to explore the effect of three different electrolytes on magnesite (MgCO3) dissolution at pH 2. The experiments showed that the magnesite dissolution rate varied in the order NO3->Cl>SO42- when these anions were present in solution. Under the experimental conditions magnesite dissolution occurred via the removal of successive single surface layers, where changes in magnesite reactivity in the presence of different electrolytes could be observed as variations in the cycle length for the removal of one unit cell layer. The cycles began with the formation of sporadically distributed etch pits followed by the nucleation of homogeneously distributed etch pits. Coalescence of the etch pits formed isolated sections of the remnant surface, which then dissolved away. The timing of sporadic and homogeneous etch pit nucleation was constant despite the presence of different anions. However, the cycles in surface roughness and etch pit spreading rates indicate that the different anions affect step retreat rates and hence dissolution rates. Differences in magnesite reactivity can be attributed to the direct interaction of sulphate with the magnesite surface and the indirect effects of chloride and nitrate on the magnesite surface hydration and hydration of the Mg2+ ion in solution. In all experiments during the dissolution process evidence for the precipitation of a new phase was observed, either directly as precipitates forming on the magnesite surface in the AFM and after the experiments, seen in SEM analysis, or as changes in the Mg outlet concentration during flow-through experiments. EDX and Raman spectroscopy were used to analyse the composition of the precipitate and although it could not be definitively identified, considering previous observations the precipitate is most likely a hydrated Mg-carbonate phase with a MgCO3·xH2O

  20. Ion Composition of Titan's Ionosphere Observed During T9 Magnetotail Crossing

    NASA Technical Reports Server (NTRS)

    Sittler, Edward; Hartle, Richard; Cooper, John; Shappirio, Marcus; Johnson, Robert; Simpson, David

    2011-01-01

    In a recent paper, Sittler et al., (2010) presented new results on the T9 encounter by the Cassini spacecraft when it passed through Titan s induced magnetotail. Two crossings were observed, but the first crossing, event 1, is thought to be out flowing ionosphere plasma. T9 is ideal for CAPS IMS probing of the ionosphere, since the ion densities at the higher altitudes of the T9 flyby approx. 10,000 km, allows measurements to be made down to 1 eV without saturating its detectors. Sittler et al., (2010) reported possible detection of NH4+ ions, but favored the detection of CH5+ and C2H5+ ions. In this report we investigate both the medium mass resolution (straight through (ST)) and high mass resolution (linear electric field (LEF)) composition data from the Cassini Plasma Spectrometer (CAPS) Ion Mass Spectrometer (IMS). We present a more in depth analysis of the composition data and make comparisons with ionospheric models including nitrogen chemistry such as that by Vuitton et al. (2007). The LEF data does not support NH4+ identification, but favors a CH5+ and C2H5+ identification, but also molecular ions C2N+ and CH2NH2+ are chemically allowed possibilities.

  1. Experimental observations and finite element analysis of the initiation of fiber microbuckling in notched composite laminates

    NASA Technical Reports Server (NTRS)

    Guynn, E. Gail; Bradley, Walter L.

    1989-01-01

    An understanding was developed of the factors that determine the semi-circular edge-notched compressive strength and the associated failure mode(s) were identified of thermoplastic composite laminates with multidirectional stacking sequences. The experimental observations and the detailed literature review suggest at least four factors that affected the determination of the strain levels at which fiber microbuckling initiates and thus, partially control the composite's compression strength. The dependent variables studied are the compressive strength of a reduced gage section compression specimen and the compression strength of a compression specimen with two semi-circular edge notches (no opposite free edges) centered along the gage section. In this research, specimens containing two semi-circular edge notches (no opposite free edges) were loaded in compression at a relatively slow rate to provide more stable development of fiber microbuckling damage. The results indicate that the local constraints (free surfaces, supporting ply orientation, and resin-rich regions) significantly affect the strain level for the initiation of in-plane fiber microbuckling. Preliminary results at an elevated temperature, 77 C, showed the shear stress yield strength of the resin was reduced and consequently, the resistance to fiber microbuckling was also reduced. The finite element analysis of the perfectly straight fiber problem indicates that the free surface effect causes a 10 percent reduction in the critical buckling strain. However, the experimentally measured reduction for fibers with an initial fiber curvature, was 35 percent.

  2. [Application of composite resin inlays to deciduous molars--a clinical observation of the resin onlay].

    PubMed

    Yamamoto, H; Iyori, H; Kanomi, R; Yao, K; Hieda, T

    1990-01-01

    Although composite resin has been used as an aesthetic restorative material, wear and fracture of the resin of fracture of the tooth structure are likely to occur when the size of the dental cavities are large. In addition to the lack of the aesthetic value, clinical results of prefabricated metal crown revealed several problems which were caused by the wear of the metal and the ill-adaptation of the cervical margin. In the present study, 50 devitalized deciduous molars were treated with composite resin onlays which were designed to cover the entire occlusal surface of the deciduous molar, and the clinical results were evaluated for a 6 month period. Additionally, for the purpose of simplification of the laboratory process for making resin onlays, ready-made occlusal shells were fabricated. The variety of the prepared shell size consisted of 7 sizes for the first deciduous molar, 9 sizes for the upper second deciduous molar and 10 sizes for the lower deciduous molar. The following results were obtained. 1) A partial resin fracture at the peripheral area of the mesio-buccal cuspid was found in five cases out of 50. 2) A glossy appearance on the surface of the onlay which was created by coated unfilled resin disappeared after 6 months of observation. 3) In relation to the resin onlay, when the antagonistic tooth was restored with prefabricated metal crowns, holes were made by attrition on all the crowns within a 3-4 month period.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2133972

  3. Energy-dependent volume regulation in primary cultured cerebral astrocytes.

    PubMed

    Olson, J E; Sankar, R; Holtzman, D; James, A; Fleischhacker, D

    1986-08-01

    Cell volume regulation and energy metabolism were studied in primary cultured cerebral astrocytes during exposure to media of altered osmolarity. Cells suspended in medium containing 1/2 the normal concentration of NaCl (hypoosmotic) swell immediately to a volume 40-50% larger than cells suspended in isoosmotic medium. The cell volume in hypoosmotic medium then decreases over 30 min to a volume approximately 25% larger than cells in isoosmotic medium. In hyperosmotic medium (containing twice the normal concentration of NaCl), astrocytes shrink by 29%. Little volume change occurs following this initial shrinkage. Cells resuspended in isoosmotic medium after a 30 min incubation in hypoosmotic medium shrink immediately to a volume 10% less than the volume of cells incubated continuously in isoosmotic medium. Thus, the regulatory volume decrease (RVD) in hypoosmotic medium involves a net reduction of intracellular osmoles. The RVD is partially blocked by inhibitors of mitochondrial electron transport but is unaffected by an inhibitor of glycolysis or by an uncoupler of oxidative phosphorylation. Inhibition of RVD by these metabolic agents is correlated with decreased cellular ATP levels. Ouabain, added immediately after hypoosmotic induced swelling, completely inhibits RVD, but does not alter cell volume if added after RVD has taken place. Ouabain also inhibits cell respiration 27% more in hypoosmotic medium than in isoosmotic medium indicating that the (Na,K)-ATPase-coupled ion pump is more active in the hypoosmotic medium. These data suggest that the cell volume response of astrocytes in hypoosmotic medium involves the net movement of osmoles by a mechanism dependent on cellular energy and tightly coupled to the (Na,K)-ATPase ion pump. This process may be important in the energy-dependent osmoregulation in the brain, a critical role attributed to the astrocyte in vivo. PMID:3015986

  4. An Introduction to Critical Points for Biophysicists; Observations of Compositional Heterogeneity in Lipid Membranes

    PubMed Central

    Honerkamp-Smith, Aurelia R.; Veatch, Sarah L.; Keller, Sarah L.

    2011-01-01

    Scaling laws associated with critical points have the power to greatly simplify our description of complex biophysical systems. For the general reader, we first review basic concepts and equations associated with critical phenomena for the general reader. We then apply these concepts to the specific biophysical system of lipid membranes. We recently reported that lipid membranes can contain composition fluctuations that behave in a manner consistent with the two-dimensional Ising universality class. Near the membrane’s critical point, these fluctuations are micron-sized, clearly observable by fluorescence microscopy. At higher temperatures, above the critical point, we expect to find submicron fluctuations. In separate work, we have reported that plasma membranes isolated directly from cells exhibit the same Ising behavior as model membranes do. We review other models describing submicron lateral inhomogeneity in membranes, including microemulsions, nanodomains, and mean field critical fluctuations, and we describe experimental tests that may distinguish these models. PMID:18930706

  5. Early Solar Wind Observations from the Plasma and Suprathermal Ion Composition (PLASTIC) Experiments on STEREO

    NASA Astrophysics Data System (ADS)

    Galvin, A. B.; Kistler, L. A.; Popecki, M. A.; Farrugia, C.; Moebius, E.; Lee, M.; Ellis, L.; Simunac, K.; Singer, K.; Russell, C.; Walker, C.; Blush, L.; Klecker, B.; Wimmer-Schweingruber, R. F.; Thompson, B.; Bochsler, P.; Wurz, P.; Daoudi, H.; Giammanco, C.; Karrer, R.; Opitz, A.; Koeten, M.; Luhmann, J.; Howard, R.; Wuelser, J. P.; Acuna, M.

    2007-05-01

    Two identical Plasma and Suprathermal Ion Composition (PLASTIC) instruments are now flying on the STEREO A and B observatories, which launched in October 2006. The STEREO observatories are drifting away from the Earth and from each other, providing different longitudinal perspectives. PLASTIC together with the IMPACT suite provides the in-situ measurements for the STEREO mission, while SECCHI provides remote imaging of the solar corona. The PLASTIC solar wind sector measures solar wind proton bulk parameters and provides species identification and relative abundances for the more dominant solar wind minor (Z>2) ions. During this early part of the STEREO mission, as we approach solar minimum conditions, there have been a series of coronal- hole associated high speed streams and interstream sector boundaries. In this talk we will provide initial observations of the solar wind during selected time periods.

  6. Characterizing energy dependence and count rate performance of a dual scintillator fiber-optic detector for computed tomography

    SciTech Connect

    Hoerner, Matthew R. Stepusin, Elliott J.; Hyer, Daniel E.; Hintenlang, David E.

    2015-03-15

    Purpose: Kilovoltage (kV) x-rays pose a significant challenge for radiation dosimetry. In the kV energy range, even small differences in material composition can result in significant variations in the absorbed energy between soft tissue and the detector. In addition, the use of electronic systems in light detection has demonstrated measurement losses at high photon fluence rates incident to the detector. This study investigated the feasibility of using a novel dual scintillator detector and whether its response to changes in beam energy from scatter and hardening is readily quantified. The detector incorporates a tissue-equivalent plastic scintillator and a gadolinium oxysulfide scintillator, which has a higher sensitivity to scatter x-rays. Methods: The detector was constructed by coupling two scintillators: (1) small cylindrical plastic scintillator, 500 μm in diameter and 2 mm in length, and (2) 100 micron sheet of gadolinium oxysulfide 500 μm in diameter, each to a 2 m long optical fiber, which acts as a light guide to transmit scintillation photons from the sensitive element to a photomultiplier tube. Count rate linearity data were obtained from a wide range of exposure rates delivered from a radiological x-ray tube by adjusting the tube current. The data were fitted to a nonparalyzable dead time model to characterize the time response. The true counting rate was related to the reference free air dose air rate measured with a 0.6 cm{sup 3} Radcal{sup ®} thimble chamber as described in AAPM Report No. 111. Secondary electron and photon spectra were evaluated using Monte Carlo techniques to analyze ionization quenching and photon energy-absorption characteristics from free-in-air and in phantom measurements. The depth/energy dependence of the detector was characterized using a computed tomography dose index QA phantom consisting of nested adult head and body segments. The phantom provided up to 32 cm of acrylic with a compatible 0.6 cm{sup 3} calibrated

  7. Cosmic Origins Spectrograph Observations of the Chemical Composition of SNR LMC N132D

    NASA Astrophysics Data System (ADS)

    France, Kevin; Beasley, Matthew; Keeney, Brian A.; Danforth, Charles W.; Froning, Cynthia S.; Green, James C.; Shull, J. Michael

    2009-12-01

    We present new far-ultraviolet (far-UV) spectra of an oxygen-rich knot in the Large Magellanic Cloud supernova remnant N132D, obtained with the Hubble Space Telescope (HST)-Cosmic Origins Spectrograph (COS). Moderate-resolution (Δv ≈ 200 km s-1) spectra in the HST far-UV bandpass (1150 Å lsim λ lsim 1750 Å) show emission from several ionization states of oxygen as well as trace amounts of other species. We use the improvements in sensitivity and resolving power offered by COS to separate contributions from different velocity components within the remnant, as well as emission from different species within the oxygen-rich knot itself. This is the first time that compositional and velocity structure in the ultraviolet emission lines from N132D have been resolved. No nitrogen is detected in N132D, and multiple carbon species are found at velocities inconsistent with the main oxygen component. We find helium and silicon to be associated with the oxygen-rich knot and use the reddening-corrected line strengths of O III], O IV], O V, and Si IV to constrain the composition and physical characteristics of this oxygen-rich knot. We find that models with a silicon-to-oxygen abundance ratio of N(Si)/N(O) = 10-2 can reproduce the observed emission for a shock velocity of ~130 km s-1, implying a mass of ~50 M sun for the N132D progenitor star. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555.

  8. Biogenic Contributions to Summertime Arctic Aerosol: Observations of Aerosol Composition from the Netcare 2014 Aircraft Campaign

    NASA Astrophysics Data System (ADS)

    Willis, M. D.; Burkart, J.; Koellner, F.; Schneider, J.; Bozem, H.; Hoor, P. M.; Brauner, R.; Herber, A. B.; Leaitch, W. R.; Abbatt, J.

    2014-12-01

    The Arctic is a complex and poorly studied aerosol environment, impacted by strong anthropogenic contributions during winter months and by regional sources in cleaner summer months. In order to gain a predictive understanding of the changing climate in this region, it is necessary to understand the balance between these two aerosol sources to clarify how aerosol might be altered by or contribute to climate change. We present results of vertically resolved, submicron aerosol composition from an Aerodyne high-resolution aerosol mass spectrometer (AMS) during the NETCARE 2014 Polar6 aircraft campaign. The campaign was based in the high Arctic, at Resolute, NU (74°N), allowing measurements from 60 to 2900 meters over ice, open water and near the ice-edge. Concurrent measurements aboard the Polar6 included ultrafine and accumulation mode particle number and size, cloud condensation nuclei concentrations, trace gas concentrations and single particle composition. Aerosol vertical profiles measured by the AMS can be broadly characterized into two regimes corresponding to different meteorological conditions: the first with very low aerosol loading (<0.1 μg/m3) at low altitudes compared to that aloft and high numbers of nucleation mode particles, and the second with higher concentrations at lower levels. This second regime was associated with low concentrations of nucleation mode particles, and higher observable levels of methane sulphonic acid (MSA) from AMS measurements at low altitudes. MSA, produced during the oxidation of dimethyl sulphide, is a marker for the contribution of ocean-derived biogenic sulphur to particulate sulphur and could be identified and quantified using the high-resolution AMS. MSA to sulphate ratios were observed to increase towards lower altitudes, suggesting a contribution to aerosol loading from the ocean. In addition, we present measurements of aerosol neutralization and the characteristics of organic aerosol that relate to the growth of

  9. Constraints on the Compositions of Phobos and Deimos from Visible/Near Infrared Observations

    NASA Astrophysics Data System (ADS)

    Fraeman, Abigail; Murchie, S.; Clark, R.; Morris, R.; Arvidson, R.; Rivkin, A.; Vilas, F.

    2013-10-01

    Mapping of mineral absorptions on Phobos and Deimos using recently acquired visible and near infrared observations from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) shows that Fe2+ electronic absorptions diagnostic of olivine and pyroxene are absent, indicating the moons' surfaces are inconsistent with a composition like that of bulk Mars or Mars crustal material. There is a broad absorption centered around 0.65 µm within the redder spectral unit on Phobos and ubiquitously present on Deimos, and the occurrence of this feature is independently confirmed by telescopic spectra of Phobos collected from the Mayall 4-m telescope. A comparable 0.65 µm feature is also found to be present among numerous other low-albedo solar system bodies. Thermally corrected CRISM spectra additionally show a 2.7 μm feature present in spectra collected across all of Phobos and Deimos, and this feature is generally stronger in red unit material. The shape and position of the 2.7 μm band are consistent with an OH related feature. The origin of the 0.65 um feature is uncertain, and we will discuss evidence for or against it being one of several candidate phases including a mixture of microphase and nanophase metallic iron that may have formed on the moons' surfaces through space weathering, as has been proposed for dark material on Iapetus, or an Fe-bearing phyllosilicate, a common mineral in the moons' closest spectral analogs CM chrondrites. Overall, the CRISM observations indicate Phobos and Deimos most likely have a composition consistent with a primitive, hydroxyl-bearing material everywhere, with a variation in the phase that is responsible for the 0.65 µm band. Spectral data with a greater spectral range, including into the vacuum ultraviolet, could help further constrain the 0.65 µm phase, although in situ investigation will be necessary for definitive identification off the responsible material.

  10. Energy dependence of the optical model of neutron scattering from niobium

    SciTech Connect

    Smith, A.B.; Guenther, P.T.; Lawson, R.D.

    1985-05-01

    Neutron differential-elastic-scattering cross sections of niobium were measured from 1.5 to 10.0 MeV at intervals of less than or equal to200 keV below 4.0 MeV, and of approx. =500 keV from 4.0 to 10.0 MeV. Ten to more than fifty differential-cross-section values were determined at each incident energy, distributed over the angular range approx. =20 to 160/sup 0/. The observed values were interpreted in the context of the spherical optical-statistical model. It was found that the volume integral of the real potential decreased with energy whereas the integral of the imaginary part increased. The energy dependence in both cases was consistent with a linear variation. There is a dispersion relationship between the real and imaginary potentials, and when this was used, in conjunction with the experimental imaginary potential, it was possible to predict the observed energy dependence of the real potential to a good degree of accuracy, thus supporting the consistency of the data and its analysis. The real-potential well depths needed to give the correct binding energies of the 2d/sub 5/2/, 3s/sub 1/2/, 2d/sub 3/2/ and 1g/sub 7/2/ particle states and of the 1g/sub 9/2/ hole state are in reasonable agreement with those given by a linear extrapolation of the scattering potential. However, the well depths needed to give the observed binding of the 2p/sub 3/2/, 1f/sub 5/2/ and 2p/sub 1/2/ hole states are about 10% less than the extrapolated values. 40 refs., 5 figs.

  11. Retrieval of Mars' Upper Atmospheric Composition using Dayglow Observations by IUVS on MAVEN

    NASA Astrophysics Data System (ADS)

    Correira, J.; Evans, J. S.; Stevens, M. H.; Lumpe, J. D., Jr.; Schneider, N. M.; Stewart, I. F.; Deighan, J.; Jain, S.; Chaffin, M.; Crismani, M. M. J.; Stiepen, A.; McClintock, B.; Holsclaw, G.; Lefèvre, F.; Lo, D.; Clarke, J. T.; Epavier, F.; Thiemann, E.; Chamberlin, P. C.; Bougher, S. W.; Bell, J. M.; Mahaffy, P. R.; Benna, M.; Jakosky, B. M.

    2015-12-01

    We present direct retrievals of neutral and ion number densities in Mars's upper atmosphere using FUV and MUV dayglow observations from 130 - 200 km. Atmospheric composition is inferred using the Atmospheric Ultraviolet Radiance Integrated Code [Strickland et al., 1999] adapted to the Martian atmosphere [Evans et al., 2015]. For our retrievals we use emission features observed by IUVS on MAVEN under daytime conditions over both northern and southern hemispheres from October 2014 to September 2015. We use retrieved CO2 densities to derive temperature variability between 150 - 220 km. We also investigate the sensitivity of neutral and ion density retrievals to variability in solar irradiance, solar longitude, and local time. We compare our retrievals to predictions from the Mars Global Ionosphere-Thermosphere Model [MGITM, Bougher et al., 2015], as well as in situ measurements by the Neutral Gas Ionizing Mass Spectrometer [NGIMS, Mahaffy et al., 2014], and quantify the differences throughout the altitude region of interest. The N2/CO2 ratio is used to show that N2 is in the diffusively separated region of the Martian atmosphere with a mean mixing ratio that is consistent with model predictions from MGITM, as well as in situ measurements by Viking 1 & 2 [Nier and McElroy, 1977] and NGIMS.

  12. Observations on the formation, growth and chemical composition of aerosols in an urban environment.

    PubMed

    Crilley, Leigh R; Jayaratne, E Rohan; Ayoko, Godwin A; Miljevic, Branka; Ristovski, Zoran; Morawska, Lidia

    2014-06-17

    The charge and chemical composition of ambient particles in an urban environment were determined using a neutral particle and air ion spectrometer and an aerodyne compact time-of-flight aerosol mass spectrometer. Particle formation and growth events were observed on 20 of the 36 days of sampling, with eight of these events classified as strong. During these events, peaks in the concentration of intermediate and large ions were followed by peaks in the concentration of ammonium and sulfate, which were not observed in the organic fraction. Comparison of days with and without particle formation events revealed that ammonium and sulfate were the dominant species on particle formation days while high concentrations of biomass burning OA inhibited particle growth. Analyses of the degree of particle neutralization lead us to conclude that an excess of ammonium enabled particle formation and growth. In addition, the large ion concentration increased sharply during particle growth, suggesting that during nucleation the neutral gaseous species ammonia and sulfuric acid react to form ammonium and sulfate ions. Overall, we conclude that the mechanism of particle formation and growth involved ammonia and sulfuric acid, with limited input from organics. PMID:24847803

  13. Direct Observations of Heterogeneous Dust Processing in the Troposphere: Ambient Measurements, Source Compositions and Laboratory Studies

    NASA Astrophysics Data System (ADS)

    Sullivan, R. C.; Guazzotti, S.; Sodeman, D.; Coffee, K.; Holecek, J.; Spencer, M.; Prather, K. A.

    2004-12-01

    The size and chemical composition of single dust particles in both background marine air and during dust events was determined using Aerosol Time-of-Flight Mass Spectrometry (ATOFMS) throughout the Indian and Pacific Oceans and Pacific coast during three major field campaigns: INDOEX, ACE-Asia and CIFEX. In general the chemical associations within individual particle spectra for the major dust particle types were very similar in all sampling locations. The dust mass spectra were dominated by various combinations of potassium, calcium, iron, and aluminum, with contributions from silicates, sodium, chloride and titanium oxides. The relative ion intensities often differed suggesting that the dust is a complex, externally mixed aggregate of varying mineral origins. Evidence of heterogeneous processing of the dust particles was also observed with ATOFMS using markers for nitrate, sulphate, and organic species. Aging of dust particles can dramatically alter their radiative and cloud-forming properties, changing the effects that dust will have on global climate. The dust spectra were also compared with those measured from collected dust, sand and soil samples in Asia and the United States. In general the mass spectra of the ambient and source dust particles were very similar, except that for the most part the source samples lacked evidence of atmospheric aging. Preliminary lab studies examining heterogeneous processing of dust in a flow tube will be presented. These studies investigate the relative reactivity of the different types of dust observed in the atmosphere and the competitive heterogeneous chemistry of dust and sea salt particles.

  14. In-situ observation of nucleated polymer crystallization in polyoxymethylene sandwich composites

    NASA Astrophysics Data System (ADS)

    Slouf, Miroslav; Krejcikova, Sabina; Vackova, Tatana; Kratochvil, Jaroslav; Novak, Libor

    2015-03-01

    We introduce a dynamic sandwich method, which can be used for in-situ observation and quantification of polymer crystallization nucleated by micro/nanoparticles. The method was applied on polyoxymethylene (POM) composites with three nucleating agents: talc micropowder (POM/mTalc), chalk nanopowder (POM/nChalk) and titanate nanotubes (POM/TiNT). The nucleating agents were deposited between polymer films, the resulting sandwich samples were consolidated by thermal treatment, and their microtomed cross-sections were observed during isothermal crystallization by polarized light microscopy. As the intensity of polarized light was shown to be proportional to the relative crystallinity, the PLM results could be fitted to Avrami equation and the nucleating activity of all investigated particles could be quantified by means of Avrami parameters (n, k). The crystallization half-times increased reproducibly in the following order: POM/nChalk < POM/mTalc < POM/TiNT ~ POM. For strong nucleating agents (mTalc, nChalk), the crystallization kinetics corresponded to spontaneous crystallization starting from central nucleating layer, which was verified by computer simulations. The results were also confirmed by DSC. We concluded that the sandwich method is an efficient microscopic technique for detailed evaluation of nucleating activity of arbitrary micro/nanoparticles in polymer systems.

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

    NASA Astrophysics Data System (ADS)

    van Diedenhoven, B.; Perlwitz, J. P.; Fridlind, A. M.; Chowdhary, J.; Cairns, B.; Stangl, A. J.

    2015-12-01

    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.

  16. 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.

  17. Elemental and charge state composition of the fast solar wind observed with SMS instruments on WIND

    NASA Technical Reports Server (NTRS)

    Gloeckler, G.; Galvin, A. B.; Ipavich, F. M.; Hamilton, D. C.; Bochsler, P.; Geiss, J.; Fisk, L. A.; Wilken, B.

    1995-01-01

    The elemental composition and charge state distributions of heavy ions of the solar wind provide essential information about: (1) atom-ion separation processes in the solar atmosphere leading to the 'FIP effect' (the overabundance of low First Ionization potential (FIP) elements in the solar wind compared to the photosphere); and (2) coronal temperature profiles, as well as mechanisms which heat the corona and accelerate the solar wind. This information is required for solar wind acceleration models. The SWICS instrument on Ulysses measures for all solar wind flow conditions the relative abundance of about 8 elements and 20 charge states of the solar wind. Furthermore, the Ulysses high-latitude orbit provides an unprecedented look at the solar wind from the polar coronal holes near solar minimum conditions. The MASS instrument on the WIND spacecraft is a high-mass resolution solar wind ion mass spectrometer that will provide routinely not only the abundances and charge state of all elements easily measured with SWICS, but also of N, Mg, S. The MASS sensor was fully operational at the end of 1994 and has sampled the in-ecliptic solar wind composition in both the slow and the corotating fast streams. This unique combination of SWICS on Ulysses and MASS on WIND allows us to view for the first time the solar wind from two regions of the large coronal hole. Observations with SWICS in the coronal hole wind: (1) indicate that the FIP effect is small; and (2) allow us determine the altitude of the maximum in the electron temperature profile, and indicate a maximum temperature of approximately 1.5 MK. New results from the SMS instruments on Wind will be compared with results from SWICS on Ulysses.

  18. Pollution in the Summertime Canadian High Arctic observed during NETCARE 2014: Investigation of origin and composition

    NASA Astrophysics Data System (ADS)

    Köllner, Franziska; Schneider, Johannes; Bozem, Heiko; Hoor, Peter; Willis, Megan; Burkart, Julia; Leaitch, Richard; Abbatt, Jon; Herber, Andreas; Borrmann, Stephan

    2015-04-01

    The clean and sensitive Arctic atmosphere is influenced by transport of air masses from lower latitudes that bring pollution in the form of aerosol particles and trace gases into the Arctic regions. However, the transport processes causing such pollution events are yet not sufficiently well understood. Here we report on results from the aircraft campaign NETCARE 2014 that took place in July 2014 in Resolute Bay, Nunavut (Canada) as part of the "Network on Climate and Aerosols: Addressing Key Uncertainties in Remote Canadian Environment" (NETCARE). These airborne measurements add to only a very few of such measurements conducted in the Arctic during the summertime. The instrumentation on board the research aircraft Polar 6 (operated by the Alfred Wegener Institute for Polar and Marine Research) included a large set of physico-chemical aerosol analysis instruments, several trace gas measurements and basic meteorological parameters. Here we focus on observed pollution events that caused elevated trace gas and aerosol concentrations in the summertime Canadian High Arctic between 50 and 3500 m. In order to better understand the chemical composition and the origin of those polluted air masses, we use single particle aerosol composition obtained using the Aircraft-based Laser Ablation Aerosol Mass Spectrometer (ALABAMA), combined with aerosol size distributions and number concentrations from an Optical Particle Counter as well as trace gas measurements of CO and CO2. CO and CO2 are important tracers to study pollution events, which are connected to anthropogenic and non-anthropogenic combustion processes, respectively biomass burning and fossil fuel combustion. The ALABAMA provides a detailed single particle aerosol composition analysis from which we identify different particle types like soot-, biomass burning-, organics-, diesel exhaust- and metallic particles. The measurements were compared to Lagrangian models like FLEXPART and LAGRANTO to find the pollution sources

  19. Monte Carlo Computational Modeling of the Energy Dependence of Atomic Oxygen Undercutting of Protected Polymers

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A.; Stueber, Thomas J.; Norris, Mary Jo

    1998-01-01

    A Monte Carlo computational model has been developed which simulates atomic oxygen attack of protected polymers at defect sites in the protective coatings. The parameters defining how atomic oxygen interacts with polymers and protective coatings as well as the scattering processes which occur have been optimized to replicate experimental results observed from protected polyimide Kapton on the Long Duration Exposure Facility (LDEF) mission. Computational prediction of atomic oxygen undercutting at defect sites in protective coatings for various arrival energies was investigated. The atomic oxygen undercutting energy dependence predictions enable one to predict mass loss that would occur in low Earth orbit, based on lower energy ground laboratory atomic oxygen beam systems. Results of computational model prediction of undercut cavity size as a function of energy and defect size will be presented to provide insight into expected in-space mass loss of protected polymers with protective coating defects based on lower energy ground laboratory testing.

  20. Energy-Dependent Ionization States of Shock-Accelerated Particles in the Solar Corona

    NASA Technical Reports Server (NTRS)

    Reames, Donald V.; Ng, C. K.; Tylka, A. J.

    2000-01-01

    We examine the range of possible energy dependence of the ionization states of ions that are shock-accelerated from the ambient plasma of the solar corona. If acceleration begins in a region of moderate density, sufficiently low in the corona, ions above about 0.1 MeV/amu approach an equilibrium charge state that depends primarily upon their speed and only weakly on the plasma temperature. We suggest that the large variations of the charge states with energy for ions such as Si and Fe observed in the 1997 November 6 event are consistent with stripping in moderately dense coronal. plasma during shock acceleration. In the large solar-particle events studied previously, acceleration occurs sufficiently high in the corona that even Fe ions up to 600 MeV/amu are not stripped of electrons.

  1. Energy dependent saturation width of swift heavy ion shaped embedded Au nanoparticles

    NASA Astrophysics Data System (ADS)

    Kluth, P.; Giulian, R.; Sprouster, D. J.; Schnohr, C. S.; Byrne, A. P.; Cookson, D. J.; Ridgway, M. C.

    2009-03-01

    The transformation of Au nanoparticles (NPs) embedded in SiO2 from spherical to rod-like shapes induced by swift heavy ion irradiation has been studied. Irradiation was performed with A197u ions at energies between 54 and 185 MeV. Transmission electron microscopy and small angle x-ray scattering measurements reveal an energy dependent saturation width of the NP rods as well as a minimum size required for the NPs to elongate. The NP saturation width is correlated with the ion track diameter in the SiO2. NP melting and in-plane strain in the irradiated SiO2 are discussed as potential mechanisms for the observed deformation.

  2. Incident Energy Dependence of pt Correlations at RHIC

    SciTech Connect

    Adams, J.; Aggarwal, M. M.; Ahammed, Z.; Amonett, J.; Anderson, B. D.; Arkhipkin, D.; Averichev, G. S.; Badyal, S. K.; Bai, Y.; Balewski, J.; Barannikova, O.; Barnby, L. S.; Baudot, J.; Bekele, S.; Belaga, V. V.; Bellwied, R.; Berger, J.; Bezverkhny, B. I; Bharadwaj, S.; Bhasin, A.; Bhati, A. K.; Bhatia, V. S.; Bichsel, H.; Billmeier, A.; Bland, L. C.; Blyth, C. O.; Bonner, B. E.; Botje, M.; Boucham, A.; Brandin, A. V.; Bravar, A.; Bystersky, M.; Cadman, R. V.; Cai, X. Z.; Caines, H.; Castillo, J.; Cebra, D.; Chajecki, Z.; Chaloupka, P.; Chattopadhyay, S.; Chen, H. F.; Chen, Y.; Cheng, J.; Cherney, M.; Chikanian, A.; Christie, W.; Coffin, J. P.; Cormier, T. M.; Cramer, J. G.; Crawford, H. J.; Das, D.; Das, S.; de Moura, M. M.; Derevschikov, A. A.; Didenko, L.; Dietel, T.; Dogra, S. M.; Dong, W. J.; Dong, X.; Draper, J. E.; Du, F.; Dubey, A. K.; Dunin, V. B.; Dunlop, J. C.; Dutta Mazumdar, M. R.; Eckardt, V.; Edwards, W. R.; Efimov, L. G.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Fachini, P.; Faivre, J.; Fatemi, R.; Fedorisin, J.; Filimonov, K.; Filip, P.; Finch, E.; Fine, V.; Fisyak, Y.; Fomenko, K.; Fu, J.; Gagliardi, C. A.; Gaillard, L.; Gans, J.; Ganti, M. S.; Gaudichet, L.; Geurts, F.; Ghazikhanian, V.; Ghosh, P.; Gonzalez, J. E.; Grachov, O.; Grebenyuk, O.; Grosnick, D.; Guertin, S. M.; Guo, Y.; Gupta, A.; Gutierrez, T. D.; Hallman, T. J.; Hamed, A.; Hardtke, D.; Harris, J. W.; Heinz, M.; Henry, T. W.; Hepplemann, S.; Hippolyte, B.; Hirsch, A.; Hjort, E.; Hoffmann, G. W.; Huang, H. Z.; Huang, S. L.; Hughes, E. W.; Humanic, T. J.; Igo, G.; Ishihara, A.; Jacobs, P.; Jacobs, W. W.; Janik, M.; Jiang, H.; Jones, P. G.; Judd, E. G.; Kabana, S.; Kang, K.; Kaplan, M.; Keane, D.; Khodyrev, V. Yu; Kiryluk, J.; Kisiel, A.; Kislov, E. M.; Klay, J.; Klein, S. R.; Koetke, D. D.; Kollegger, T.; Kopytine, M.; Kotchenda, L.; Kramer, M.; Kravtsov, P.; Kravtsov, V. I.; Krueger, K.; Kuhn, C.; Kulikov, A. I.; Kumar, A.; Kutuev, R. Kh

    2005-10-01

    We present results for two-particle transverse momentum correlations, Δpt,iΔt,j, as a function of event centrality for Au+Au collisions at √(sNN) = 20, 62, 130, and 200 GeV at the Relativistic Heavy Ion Collider. We observe correlations decreasing with centrality that are similar at all four incident energies. The correlations multiplied by the multiplicity density increase with incident energy and the centrality dependence may show evidence of processes such as thermalization, jet production, or the saturation of transverse flow. The square root of the correlations divided by the event-wise average transverse momentum per event shows little or no beam energy dependence and generally agrees with previous measurements at the Super Proton Synchrotron.

  3. Energy dependence of power-spectral noise in X-ray binaries

    NASA Astrophysics Data System (ADS)

    Stiele, Holger; Yu, Wenfei

    2014-08-01

    Black hole and neutron star X-ray binaries show variability on time-scales ranging from milliseconds to years. In the last two decades a detailed phenomenological picture of short-term variability in low-mass X-ray binaries has emerged mainly based on RXTE observations that cover energies above 3 keV. This picture comprises periodic or quasi-periodic variability, seen as spikes or humps in power density spectra, that are superposed on broad noise components. The overall shape of the noise components as well as the occurrence of quasi-periodic oscillations is known to vary with the state of the X-ray binary. We are accomplishing a comprehensive study of archival XMM-Newton observations in timing or burst mode of more than ten black hole and more than thirty neutron star low-mass X-ray binaries to investigate the variability properties of these sources at softer energies where the thermal disk component starts to emerge.Here we present some results of the energy dependence of the noise component in power density spectra: a discussion of the energy dependence of the power spectral state that we found in the “plateau” state of GRS 1915+105 and the intermediate state of 4U 1630-47; the dependence of the break-frequency of the band-limited noise component as well as the quasi-periodic oscillations on the studied energy band in several X-ray binaries like GX 339-4 or Swift J1753.5-0127. We will discuss the implications of these findings for the picture of the accretion geometry in black hole X-ray binaries.

  4. REVEALING THE STRUCTURE OF AN ACCRETION DISK THROUGH ENERGY-DEPENDENT X-RAY MICROLENSING

    SciTech Connect

    Chartas, G.; Moore, D.; Kochanek, C. S.; Mosquera, A. M.; Blackburne, J. A.; Dai, X.

    2012-10-01

    We present results from monitoring observations of the gravitationally lensed quasar RX J1131-1231 performed with the Chandra X-Ray Observatory. The X-ray observations were planned with relatively long exposures that allowed a search for energy-dependent microlensing in the soft (0.2-2 keV) and hard (2-10 keV) light curves of the images of RX J1131-1231. We detect significant microlensing in the X-ray light curves of images A and D, and energy-dependent microlensing of image D. The magnification of the soft band appears to be larger than that in the hard band by a factor of {approx}1.3 when image D becomes more magnified. This can be explained by the difference between a compact, softer-spectrum corona that is producing a more extended, harder spectrum reflection component off the disk. This is supported by the evolution of the fluorescent iron line in image D over three consecutive time-averaged phases of the light curve. In the first period, an Fe line at E = 6.35{sup +0.14}{sub -0.14} keV is detected (at >99% confidence). In the second period, two Fe lines are detected, one at E = 5.50{sup +0.03}{sub -0.08} keV (detected at >99% confidence) and another at E = 6.04{sup +0.10}{sub -0.07} keV (marginally detected at >90% confidence), and in the third period, a broadened Fe line at 6.42{sup +0.16}{sub -0.14} keV is detected (at >99% confidence). This evolution of the Fe line profile during the microlensing event is consistent with the line distortion expected when a caustic passes over the inner disk where the shape of the fluorescent Fe line is distorted by general relativistic and Doppler effects.

  5. 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

  6. A High-Resolution 3D Weather Radar, MSG, and Lightning Sensor Observation Composite

    NASA Astrophysics Data System (ADS)

    Diederich, Malte; Senf, Fabian; Wapler, Kathrin; Simmer, Clemens

    2013-04-01

    Within the research group 'Object-based Analysis and SEamless prediction' (OASE) of the Hans Ertel Centre for Weather Research programme (HerZ), a data composite containing weather radar, lightning sensor, and Meteosat Second Generation observations is being developed for the use in object-based weather analysis and nowcasting. At present, a 3D merging scheme combines measurements of the Bonn and Jülich dual polarimetric weather radar systems (data provided by the TR32 and TERENO projects) into a 3-dimensional polar-stereographic volume grid, with 500 meters horizontal, and 250 meters vertical resolution. The merging takes into account and compensates for various observational error sources, such as attenuation through hydrometeors, beam blockage through topography and buildings, minimum detectable signal as a function of noise threshold, non-hydrometeor echos like insects, and interference from other radar systems. In addition to this, the effect of convection during the radar 5-minute volume scan pattern is mitigated through calculation of advection vectors from subsequent scans and their use for advection correction when projecting the measurements into space for any desired timestamp. The Meteosat Second Generation rapid scan service provides a scan in 12 spectral visual and infrared wavelengths every 5 minutes over Germany and Europe. These scans, together with the derived microphysical cloud parameters, are projected into the same polar stereographic grid used for the radar data. Lightning counts from the LINET lightning sensor network are also provided for every 2D grid pixel. The combined 3D radar and 2D MSG/LINET data is stored in a fully documented netCDF file for every 5 minute interval, and is made ready for tracking and object based weather analysis. At the moment, the 3D data only covers the Bonn and Jülich area, but the algorithms are planed to be adapted to the newly conceived DWD polarimetric C-Band 5 minute interval volume scan strategy. An

  7. Synoptic Mapping of Chemical Composition, Thermal Structure, and Air Motion from UARS Observations

    NASA Technical Reports Server (NTRS)

    Salby, Murry L.

    1999-01-01

    An operational mapping algorithm was developed to process measurements of individual species observed by different satellite instruments on board UARS. Based on Fast Fourier Synoptic Mapping (FFSM), the algorithm accounts for the precessing orbit of UARS, the error of individual instruments, and gaps associated with instrument duty cycle and the satellite yaw maneuver. It provides synoptic structure and evolution on periods as short as 1 day, derived collectively from all observations of an individual species. The algorithm was applied to synoptically map temperature, thickness, and several chemical constituents observed by the instruments: MLS, CLAES, ISAMS, and HALOE. Each field variable observed by these instruments was mapped twice-daily in continuous global time series several months long. Mapped behavior produced via FFSM was compared against standard archived products generated via Kalman filtering. The standard map products reveal similar behavior, but are limited to features of larger scale. Tracer structure that develops through flow deformation and attending transport is therefore represented in those products more coarsely, eventually being sheared down to scales that are no longer represented properly. The synoptic time series also reveal a diurnal cycle for several of the constituents, one that emerges clearly in their space-time spectra. The zonal and meridional structure of diurnal variability was mapped by filtering the space-time spectrum, an intermediate product of FFSM, to those scales resolved by the UARS sampling. Geographical variations of the diurnal cycle have also been evaluated in its seasonal-mean structure by compositing distributions at individual local times. Both were compared to diurnal variations in chemical models and in dynamical models that account for transport by the diurnal tide. Diurnal variations were found to introduce spurious behavior into the archived products generated via Kalman filtering, behavior that is

  8. Deriving the Structure and Composition of Enceladus’ Plume from Cassini UVIS Observations

    NASA Astrophysics Data System (ADS)

    Hansen, Candice; Esposito, Larry; Colwell, Josh; Hendrix, Amanda; Portyankina, Ganna; Shemansky, Don; West, Robert

    2015-11-01

    Cassini’s Ultraviolet Imaging Spectrograph (UVIS) has observed 4 stellar and one solar occultation by Enceladus’ water vapor plume. The July 2005 occultation observation established that water is the primary constituent of the plume [1], and allowed us to calculate the flux of water coming from the plume; the 2007 occultation showed super-sonic jets of gas imbedded within the plume [2]. The solar occultation observation set upper limits for N2 as a constituent of the plume and provided higher resolution data on the jets [3]. On 19 October 2011, epsilon and zeta Orionis were simultaneously occulted by the plume. The stars were in separate pixels on the detector, separated by 24 mrad, or ~20 km, with the lower altitude star (epsilon Orionis) 18 km above the limb at its closest point. The profile at two altitudes shows evidence for a new gas jet location, possibly between dust jet #50 and #51 identified in [4].Results from the assemblage of these data sets, with implications for the composition and vertical structure of the plume and jets, will be described. Gas being expelled from the “tiger stripe” fissures is largely on a vertical escape trajectory away from Enceladus. Upper limits are set for water vapor near the limb at latitudes well away from the south pole at 3 x 1015 cm-2. Upper limits are set for the amount of ethylene and H2 in the plume, two species of interest to the chemistry of the plume [5]. No hydrogen or oxygen emission features have been observed from Enceladus’ water vapor plume, in contrast to the purported plumes at Europa, probably due to the very different plasma environment at Saturn. Data have now been processed consistently for all occultations with slightly different results for water vapor supply to the Saturn magnetosphere than previously reported. Overall, eruptive activity has been steady to within ~20% from 2005 to 2011.References: [1] Hansen, C. J. et al., Science 311:1422 (2006). Hansen, C. J. et al., Nature 456:477 (2008

  9. Resonant Triad in Boundary-Layer Stability. Part 2; Composite Solution and Comparison with Observations

    NASA Technical Reports Server (NTRS)

    Mankbadi, Reda R.

    1991-01-01

    Here, numerical results are computed from an asymptotic near-resonance triad analysis. The analysis considers a resonant triad of instability waves consisting of a plane fundamental wave and a pair of symmetrical oblique subharmonic waves. The relevant scaling ensures that nonlinearity is confined to a distinct critical layer. The analysis is first used to form a composite solution that accounts for both the flow divergence and nonlinear effects. It is shown that the backreaction on the plane Tollmien Schlichting (TS) fundamental wave, although fully accounted for, is of little significance. The observed enhancement at the fundamental frequency disturbance is not in the plane TS wave, but is caused by nonlinearly generated waves at the fundamental frequency that result from nonlinear interactions in the critical layer. The saturation of the oblique waves is caused by their self-interaction. The nonlinear phase-locking phenomenon, the location of resonance with respect to the neutral stability curve, low frequency effects, detuning in the streamwise wave numbers, and nonlinear distortion of the mode shapes are discussed. Nonlinearity modifies the initially two dimensional Blasius profile into a fuller one with spanwise periodicity. The interactions at a wide range of unstable spanwise wave numbers are considered, and the existence of a preferred spanwise wave number is explained by means of the vorticity distribution in the critical layer. Besides presenting novel features of the phenomena and explaining the delicate mechanisms of the interactions, the results of the theory are in excellent agreement with experimental and numerical observations for all stages of the development and for various input parameters.

  10. VLT/SINFONI Observations of Europa: New Insights into the Surface Composition

    NASA Astrophysics Data System (ADS)

    Ligier, N.; Poulet, F.; Carter, J.; Brunetto, R.; Gourgeot, F.

    2016-06-01

    We present new insights into Europa’s surface composition on the global scale from linear spectral modeling of a high spectral resolution data set acquired during a ground-based observation campaign using SINFONI4, an adaptive optics near-infrared instrument on the Very Large Telescope (ESO). The spectral modeling confirms the typical “bullseye” distribution of sulfuric acid hydrate on the trailing hemisphere, which is consistent with Iogenic sulfur ion implantation. However, the traditional hypothesis of the presence of sulfate salts on the surface of the satellite is challenged as Mg-bearing chlorinated species (chloride, chlorate, and perchlorate) are found to provide improved spectral fits. The derived global distribution of Mg-chlorinated salts (and particularly chloride) is correlated with large-scale geomorphologic units such as chaos and darker areas, thus suggesting an endogenous origin. Based on the 1.65 μm water-ice absorption band shape and position, the surface temperature is estimated to be in the range 110–130 K, and water ice is found to be predominantly in its crystalline state rather than amorphous. While amorphous water ice exhibits a strong correlation with the expected intensity of the Ionian plasma torus bombardment, crystalline water ice is instead more associated with distinct geomorphological units. Endogenous processes such as jets and ice heating due to active geology may explain this relationship. Otherwise, no evidence of a correlation between grain size for the water ice and the sputtering rate has been detected so far.

  11. Observations of neutral composition and related ionospheric variations during a magnetic storm in February 1974

    NASA Technical Reports Server (NTRS)

    Hedin, A. E.; Mayr, H. G.; Brace, L. H.; Brinton, H. C.; Pelz, D. T.; Bauer, P.; Carignan, G. R.; Parks, A. D.

    1977-01-01

    The neutral-atmosphere composition experiment on Atmosphere Explorer C measured N2, O, Ar, and He densities during a magnetic storm at altitudes down to about 160 km. At latitudes above 45 deg N, N2 and Ar densities generally increase during the storm, while He and O densities decrease. Below 45 deg N all densities tend to increase during the storm. The density increases at perigee indicate that density- or temperature-profile changes are taking place below 160 km. The return to prestorm conditions is very slow, demonstrating the integrating effect of the atmospheric response. A recent theoretical model incorporating thermospheric circulation and diffusion effects reproduces the longitudinally averaged data, including latitude trends and the asymmetry about the storm maximum. Comparison with the mass-spectrometer and incoherent-scatter empirical model shows qualitative agreement with latitude trends but not with storm asymmetry, while the earlier J71 model based on total mass density is not in agreement with observed latitudinal trends. A close correlation is found between in situ O/N2 measurements and in situ and ground-based ionosonde measurements of electron density.

  12. A sliding-mode-based observer to identify faults in FBG sensors embedded in composite structures

    NASA Astrophysics Data System (ADS)

    Cazzulani, Gabriele; Cinquemani, Simone; Ronchi, Marco

    2016-04-01

    Optical strain gauges, such as Fiber Bragg Gratings (FBG), have a great potential for smart structures, thanks to their small transversal size and the possibility to make an array of many sensors. They can be embedded in composite structures and their effect on the structure is nearly negligible. These advantages make them very interesting in the field of active vibration suppression. Unfortunately their low reliability is an obstacle to their use in such applications. For this reason, this paper introduces a fault identification algorithm to identify online those sensors which are not working correctly. The algorithm is based on the use of a sliding mode observer to estimate the coherence of measurements, and then to highlight possible faults. Once identified, the corresponding sensors can be excluded from the feedback loop of the control algorithm to avoid unwanted behaviors or instabilities. Numerical and experimental tests have been carried out on a carbon fiber structure considering different fault conditions. Results show it is possible to identify the faulty sensors and thus improve the signals used in the feedback loop.

  13. Effect of liposomes on energy-dependent uptake of the antioxidant SkQR1 by isolated mitochondria.

    PubMed

    Antonenko, Yuri N; Perevoshchikova, Irina V; Rokitskaya, Tatyana I; Simonyan, Ruben A; Tashlitsky, Vadim V; Skulachev, Vladimir P

    2012-08-01

    The mitochondria-targeted antioxidant SkQR1 composed of a plastoquinone part covalently bound to a cationic rhodamine 19 moiety via a decane linker was previously shown to effectively protect brain and kidney from ischemia injury accompanying generation of reactive oxygen species. In the present paper the energy-dependent SkQR1 uptake by isolated rat liver mitochondria was studied by fluorescence correlation spectroscopy peak intensity analysis (FCS PIA). This approach can be used to measure the number of fluorescent molecules per single mitochondrion. A large portion of SkQR1 appeared to be taken up by mitochondria in an energy-independent fashion because of its high affinity to membranes. Liposomes were found to compete effectively with mitochondria for the energy-independent SkQR1 binding, thereby facilitating, as an "SkQR1-buffer", observation of energy-dependent SkQR1 accumulation in mitochondria. The rate of energy-dependent SkQR1 uptake by mitochondria observed in the presence of liposomes was rather low (minutes) which was apparently due to slow redistribution of SkQR1 between liposomal and mitochondrial membranes. This can explain the low rate of staining of mitochondria by SkQR1 in living cells containing, besides mitochondria, other membrane components (endoplasmic reticulum, Golgi membranes, endosomes, lysosomes, etc.) which can compete with mitochondria for the energy-independent SkQR1 binding. PMID:22723179

  14. Energy dependence of the band-limited noise in black hole X-ray binaries★

    NASA Astrophysics Data System (ADS)

    Stiele, H.; Yu, W.

    2015-10-01

    Black hole low-mass X-ray binaries show a variety of variability features, which manifest as narrow peak-like structures superposed on broad noise components in power density spectra in the hard X-ray emission. In this work, we study variability properties of the band-limited noise component during the low-hard state for a sample of black hole X-ray binaries. We investigate the characteristic frequency and amplitude of the band-limited noise component and study covariance spectra. For observations that show a noise component with a characteristic frequency above 1 Hz in the hard energy band (4-8 keV), we found this very same component at a lower frequency in the soft band (1-2 keV). This difference in characteristic frequency is an indication that while both the soft and the hard band photons contribute to the same band-limited noise component, which likely represents the modulation of the mass accretion rate, the origin of the soft photons is actually further away from the black hole than the hard photons. Thus, the soft photons are characterized by larger radii, lower frequencies and softer energies, and are probably associated with a smaller optical depth for Comptonization up-scattering from the outer layer of the corona, or suggest a temperature gradient of the corona. We interpret this energy dependence within the picture of energy-dependent power density states as a hint that the contribution of the up-scattered photons originating in the outskirts of the Comptonizing corona to the overall emission in the soft band is becoming significant.

  15. D/H RATIO OF TITAN FROM OBSERVATIONS OF THE CASSINI/COMPOSITE INFRARED SPECTROMETER

    SciTech Connect

    Abbas, M. M.; LeClair, A.; Kandadi, H. E-mail: andre.c.leClair@nasa.go

    2010-01-01

    The Composite Infrared Spectrometer (CIRS) aboard the Cassini spacecraft, launched in 1997 October and inserted into Saturn's orbit in 2004 July for exploration of the Saturnian system, has been making observations of Titan during its close flybys. The infrared spectra of Titan observed over a wide range of latitudes cover the 10-1400 cm{sup -1} spectral region with variable apodized resolutions from 0.53 to 15 cm{sup -1}. The spectra exhibit features of the nu{sub 4} band of methane (CH{sub 4}) in the 1300 cm{sup -1} region, and the deuterated isotope of methane (CH{sub 3}D) centered around 1156 cm{sup -1}, along with features of many trace constituents in other spectral regions, comprising hydrocarbons and nitriles in Titan's atmosphere. An analysis of the observed infrared spectra in the 1300 cm{sup -1} and 1156 cm{sup -1} regions, respectively, permits retrieval of the thermal structure and the CH{sub 3}D distributions of Titan's atmosphere. In this paper, we present a comprehensive analysis of the CIRS infrared spectra for retrieval of the CH{sub 3}D abundance and the corresponding D/H ratio in Titan's atmosphere. The analysis is based on the 0.53 cm{sup -1} resolution infrared spectra obtained during the Titan flybys from 2004 July 3 to 2008 May 28 over a range of latitudes extending from 74.{sup 0}4 N to 84.{sup 0}9 S. Using the CH{sub 4} mixing ratio of 1.4 x 10{sup -2} as measured by the Gas Chromatograph and Mass Spectrometer on the Huygens probe on the Cassini mission, we determine the D/H ratio of Titan as (1.58 +- 0.16) x 10{sup -4}, where the 1sigma uncertainty includes the standard deviation due to spectral noise and the estimated errors arising from uncertainties in the temperature retrieval, the mixing ratio of CH{sub 4}, and the spectral line parameters. Comparison of this value with the previously measured values for Titan as well as in other astrophysical sources, and its possible implications are discussed.

  16. Observation of Energy-Dependent Electron-Capture Decay in Secondary Galactic Cosmic Rays

    NASA Astrophysics Data System (ADS)

    Niebur, S. M.; Binns, W. R.; Hink, P. L.; Israel, M. H.; Klarmann, J.; Lijowski, M.; Christian, E. R.; von Rosenvinge, T. T.; Cummings, A. C.; George, J. S.; Leske, R. A.; Mewaldt, R. A.; Stone, E. C.; Wiedenbeck, M. E.; Yanasak, N. E.

    2000-04-01

    Secondary galactic cosmic rays are produced at cosmic ray energies by fragmentation of primary cosmic rays during propagation through the interstellar medium; these nuclei carry a signature of the energy at which they were produced. Although electron-capture decay is inhibited at most of the energies typical of cosmic rays, decay is possible at the lower energies for isotopes such as 51Cr and 49V. We have analyzed Titanium, Vanadium, and Chromium isotopic data from the Cosmic Ray Isotope Spectrometer on ACE and found evidence of electron-capture decay at lower energies. We will present a comparison of secondary electron-capture decay isotope abundances and abundances of their decay products with results from improved propagation models in order to discuss the amount of electron-capture decay and subsequent acceleration that may have occurred during propagation.

  17. Energy dependence of electron inelastic mean free paths in bulk GaN crystals

    NASA Astrophysics Data System (ADS)

    Krawczyk, M.; Zommer, L.; Jablonski, A.; Grzegory, I.; Bockowski, M.

    2004-09-01

    Recent advances in fabrication and commercialization of high-brightness blue and green light-emitting devices based on gallium nitride have renewed intense research of its basic properties. Since information on electron transport processes in GaN is scarce, their systematic studies are highly desirable. The electron inelastic mean free path (IMFP) is a crucial parameter for quantitative interpretation of surface electron spectra. The energy dependence of IMFP for bulk GaN crystals with different surface concentrations of their constituents was obtained from elastic peak electron spectroscopy (EPES) with use of the Ni standard in the energy range 200-2000 eV. The measured IMFPs were compared with the values predicted by the TPP-2M and G-1 formulae. A reasonable agreement was found between the measured IMFPs in bulk GaN with an ideal stoichiometric surface composition and the corresponding calculated IMFPs. Compared with the bulk IMFPs, experimental IMFPs valid for the GaN sample with a thin surface layer enriched in ˜70 at.% Ga are only slightly smaller by 5-10%, depending on the electron energy.

  18. 2008 springtime size-segregated aerosol composition observed in Seoul, Korea

    NASA Astrophysics Data System (ADS)

    Kim, S.; Lee, H.; Kim, J.; Cho, C.; Song, S.; Lim, J.; Kim, S.

    2008-12-01

    A total of 19 size-segregated particle samples were collected using two Micro-Orifice Uniform Deposit Impactors (MOUDI) in order to characterize aerosol chemical composition (mass, ions and elements) in the springtime of 2008 in Seoul, Korea. During the sampling period, there were three Asian Dust events in Seoul (March 16, April 3, and May 30-31). The average concentrations of PM10 and PM1.8 were 50.1±31.4 μg/m3 and 28.3±16.1μg/m3, respectively, with PM1.8/PM10 ratio of 0.61±0.15 indicating that fine particles dominated PM10 during the period. The high PM1.8/PM10 ratio might be explained by the location of sampling site which lies in the center of urban area. However, PM1.8/PM10 ratio was between 0.25 and 0.44 for Asian dust cases. According to our results, in general, aerosol mass concentration showed bimodal size distribution, peaked at the size range of 0.56-1μm in fine mode and 3.2-5.6μm in coarse mode. Ammonium, sulfate and nitrate ions were major components in fine mode (particles less than 1.8μm). However, unlike the other ions, nitrate ion showed peaks in both coarse mode and fine mode. Interestingly, on May 30(heavy Asian dust case), the highest nitrate ion concentration was observed in coarse mode rather than in fine mode.

  19. CCN frequency distributions and aerosol chemical composition from long-term observations at European ACTRIS supersites

    NASA Astrophysics Data System (ADS)

    Decesari, Stefano; Rinaldi, Matteo; Schmale, Julia Yvonne; Gysel, Martin; Fröhlich, Roman; Poulain, Laurent; Henning, Silvia; Stratmann, Frank; Facchini, Maria Cristina

    2016-04-01

    Cloud droplet number concentration is regulated by the availability of aerosol acting as cloud condensation nuclei (CCN). Predicting the air concentrations of CCN involves knowledge of all physical and chemical processes that contribute to shape the particle size distribution and determine aerosol hygroscopicity. The relevance of specific atmospheric processes (e.g., nucleation, coagulation, condensation of secondary organic and inorganic aerosol, etc.) is time- and site-dependent, therefore the availability of long-term, time-resolved aerosol observations at locations representative of diverse environments is strategic for the validation of state-of-the-art chemical transport models suited to predict CCN concentrations. We focused on long-term (year-long) datasets of CCN and of aerosol composition data including black carbon, and inorganic as well as organic compounds from the Aerosol Chemical Speciation Monitor (ACSM) at selected ACTRIS supersites (http://www.actris.eu/). We discuss here the joint frequency distribution of CCN levels and of aerosol chemical components concentrations for two stations: an alpine site (Jungfraujoch, CH) and a central European rural site (Melpitz, DE). The CCN frequency distributions at Jungfraujoch are broad and generally correlated with the distributions of the concentrations of aerosol chemical components (e.g., high CCN concentrations are most frequently found for high organic matter or black carbon concentrations, and vice versa), which can be explained as an effect of the strong seasonality in the aerosol characteristics at the mountain site. The CCN frequency distributions in Melpitz show a much weaker overlap with the distributions of BC concentrations or other chemical compounds. However, especially at high CCN concentration levels, a statistical correlation with organic matter (OM) concentration can be observed. For instance, the number of CCN (with particle diameter between 20 and 250 nm) at a supersaturation of 0.7% is

  20. XMM-Newton Observations of HESSJ1813-178 Reveal a Composite Supernova Remnant

    SciTech Connect

    Funk, S.; Hinton, J.A.; Moriguchi, Y.; Aharonian, F.A.; Fukui, Y.; Hofmann, W.; Horns, D.; Puehlhofer, G.; Reimer, O.; Rowell, G.; Terrier, R.; Vink, J.; Wagner, S.

    2006-11-27

    Aims--We present X-ray and {sup 12}CO(J=1-0) observations of the very-high-energy (VHE) {gamma}-ray source HESS J1813-178 with the aim of understanding the origin of the {gamma}-ray emission. Methods--High-angular resolution X-ray studies of the VHE {gamma}-ray emission region are performed using 18.6 ks of XMM-Newton data, taken on HESS J1813-178 in October 2005. Using this dataset we are able to undertake spectral and morphological studies of the X-ray emission object with greater precision than previous studies. NANTEN {sup 12}CO(J=1-0) data are used to search for correlations of the {gamma}-ray emission with molecular clouds which could act as target material for {gamma}-ray production in a hadronic scenario. Results--The NANTEN {sup 12}CO(J=1-0) observations show a giant molecular cloud of mass 2.5 x 10{sup 5} M{sub {circle_dot}} at a distance of 4 kpc in the vicinity of HESS J1813-178. Even though there is no direct positional coincidence, this giant cloud might have influenced the evolution of the {gamma}-ray source and its surroundings. The X-ray data show a highly absorbed (n{sub H} {approx} 1 x 10{sup 23} cm{sup -2}) non-thermal X-ray emitting object coincident with the previously known ASCA source AXJ1813-178 showing a compact core and an extended tail towards the north-east, located in the center of the radio shell-type Supernova remnant (SNR) G12.82-0.2. This central object shows morphological and spectral resemblance to a Pulsar Wind Nebula (PWN) and we therefore consider that this object is very likely to be a composite SNR. Nevertheless, we cannot distinguish between the scenarios in which the {gamma}-rays originate in the shell of the SNR and the one in which they originate in the central object. We discuss both scenarios in terms of a one-zone leptonic model and demonstrate, that in order to connect the core X-ray emission to the VHE {gamma}-ray emission electrons have to be accelerated to energies of at least 1 PeV. We conclude that if indeed the

  1. Entrance Channel Mass Asymmetry Effects in Sub-Barrier Fusion Dynamics by Using Energy Dependent Woods-Saxon Potential

    NASA Astrophysics Data System (ADS)

    Manjeet Singh, Gautam

    2015-12-01

    The present article highlights the inconsistency of static Woods-Saxon potential and the applicability of energy dependent Woods-Saxon potential to explore the fusion dynamics of {}4822Ti+58,60,6428Ni, {}4622Ti+{}6428Ni,{}5022Ti+{}6028Ni, and {}199F+9341Nb reactions leading to formation of different Sn-isotopes via different entrance channels. Theoretical calculations based upon one-dimensional Wong formula obtained by using static Woods-Saxon potential unable to provide proper explanation for sub-barrier fusion enhancement of these projectile-target combinations. However, the predictions of one-dimensional Wong formula based upon energy dependent Woods-Saxon potential model (EDWSP model) accurately describe the observed fusion dynamics of these systems wherein the significantly larger value of diffuseness parameter ranging from a = 0.85 fm to a = 0.97 fm is required to address the experimental data in whole range of energy. Therefore, the energy dependence in nucleus-nucleus potential simulates the influence of the nuclear structure degrees of freedom of the colliding pairs. Supported by Dr. D.S. Kothari Post-Doctoral Fellowship Scheme sponsored by University Grants Commission (UGC), New Delhi, India

  2. Comparison of clustering techniques for determining compositional units on Mercury from MESSENGER spectral observations

    NASA Astrophysics Data System (ADS)

    D'Amore, Mario; Helbert, Jorn; Maturilli, Alessandro; Marzo, Giuseppe A.; Roush, Ted L.; Hogan, Robert C.; Izenberg, Noam R.; Sprague, Ann L.; Holsclaw, Gregory M.; Head, James; McClintock, William; Solomon, Sean C.

    The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) obtained spectra of much of the surface of Mercury during the first two MESSENGER flybys of the planet. The resulting dataset is composed of several hundred reflectance spectra that have not yet been corrected for any effect due to observing geometry or to surface material phase curves. Our hypothesis is that the separation of surface signal from other contributions can be efficiently performed by the use of statistical techniques. We adopt principal component and clustering analyses to identify and characterize spectral units along the MASCS ground tracks. In order to extract the spectral shapes of the primary surface components exposed in the surface area an-alyzed, we applied an R-mode factor analysis, aiming to find an eigenvector set that minimizes data covariance. Identification of the different components and their abundances is accom-plished by principal component analysis together with an evaluation of the eigenvectors and eigenvalues of the covariance matrix (also called covariance matrix decomposition). A compar-ison of the results using only the near-infrared (NIR) and visible (VIS) portions of the spectra indicates that the NIR spectral range is carrying less information than the VIS portion. We also find that the eigenvectors are essentially unchanged if the full wavelength range is selected (VIS+NIR) rather than limiting observations to the VIS range. The full-range analysis shows that seven eigenvectors are needed to reconstruct the original spectrum to within the level of variability associated with the observational data. Each spectral eigenvector can be regarded as a representative of a distinct spectral class that varies in spatial abundance along the track. The first eigenvector always displays a strong positive or "red" slope, probably strongly linked to uncorrected effects associated with viewing geometry variations, and all eigenvectors show distinctive spectral signatures

  3. Auroral energy deposition and neutral composition changes observed simultaneously by ESRO 4 and AE-C at different altitudes

    NASA Technical Reports Server (NTRS)

    Trinks, H.; Mayr, H. G.; Kayser, D. C.; Potter, W. E.

    1977-01-01

    Neutral composition data obtained simultaneously from ESRO 4 and AE-C during geomagnetically disturbed conditions at different altitudes (160 and 230 km) are used to investigate the atmospheric response to geomagnetic storms and to infer information regarding the excitation mechanism. The data are compared with a theoretical model that estimates the composition effects in terms of wind induced diffusion. A parametric study was conducted bearing on the influence of energy deposition at different altitudes and with varying latitudinal extent. In one of the observed events the composition effects at 160 km are substantially smaller than at 230 km for which we inferred by comparison with the theory that the energy mainly was deposited at 150 km altitude over a wide latitude range. Another event required energy deposition at somewhat lower altitudes near 120 km with a more localized energy source. Significant variations of the turbopause level were not necessary to explain the observed variations.

  4. Non-Contact Ultrasound Based Guided Lamb Waves for Composite Structure Inspection: Some Interesting Observations

    NASA Astrophysics Data System (ADS)

    Karthikeyan, P.; Ramdas, C.; Bhardwaj, Mahesh C.; Balasubramaniam, Krishnan

    2009-03-01

    Quality assurance of the composite products becomes important to avoid defects during processing since they are used for critical applications. Non- Contact Ultrasound (NCU) technique using the A0 Lamb modes is explored here with applications in the detection, imaging, and sizing of defects in both honeycomb and more importantly composite laminates. A Finite Element Model was employed to understand the interactions of the Lamb modes with defects. Mode conversions at the two ends of a delamination and the time of flight differences between these were employed for the determination of the size of the delaminations in composite laminates. This method may allow for the two dimensional sizing of the delaminations in composite laminates using a single line-scan using the Lamb modes.

  5. Ulysses Composition, Plasma and Magnetic Field Observations of High Speed Solar wind Streams

    NASA Technical Reports Server (NTRS)

    Smith, E. J.

    1997-01-01

    During 1992-3 as the Ulysses spacecraft passed in and out of the southern high speed solar wind stream, the Solar Wind Ion Spectrometer, SWICS made continuous composition and temperature measurements of all major solar wind ions.

  6. One Year of Observations of Dawn at Ceres: Composition as seen by VIR

    NASA Astrophysics Data System (ADS)

    De Sanctis, M. Cristina; Ammannito, Eleonora; Ciarniello, Mauro; Raponi, Andrea; Carrozzo, F. Giacomo; Frigeri, Alessandro; Longobardo, Andrea; Palomba, Ernesto; Tosi, Federico; Zambon, Francesca; Fonte, Sergio; Formisano, Michelangelo; Giardino, Marco; Magni, Gianfranco; Capaccioni, Fabrizio; Capria, M. Teresa; Marchi, Simone; Pieters, Carle M.; Ehlmann, Bethany; McCord, Tom

    2016-04-01

    NASA's Dawn spacecraft [1] arrived at Ceres on March 5, 2015, and has been studying the dwarf planet. The Dawn mission is observing Ceres' surface with its suite of instruments [1] including a Visible and InfraRed Mapping Spectrometer (VIR-MS) [2]. VIR-MS is an imaging spectrometer coupling high spectral and spatial resolution in the VIS (0.25-1-micron) and IR (0.95-5-micron) spectral ranges. Ceres' surface is very dark, but small localized areas exhibit unexpectedly bright materials. Since the first approach data, near infrared spectra revealed a dark surface, with a strong and complex absorption band in the spectral region around 3 microns [3]. Near-infrared spectroscopic analyses confirmed previous observation of bands at 3.1, 3.3-3.5, 3.9 micron but have clearly identified a band at 2.72 micron. This characteristic narrow feature is distinctive for OH-bearing minerals, while H2O-bearing phases, show a much broader absorption band that is a poor match for the Ceres spectrum. Water ice does not fit the observed spectrum. The 3.05-3.1 μm band is also visible in Ceres' ground-based spectra, and has been previously attributed to different phases including water ice, hydrated or NH4-bearing clays and brucite [4,5,6]. We find here that the best fit is obtained with ammoniated phyllosilicate added to a dark material (likely magnetite), antigorite and carbonate [7]. These different components, including ammoniated phases, occur everywhere across the surface although with different relative abundances [8]. Particularly interesting are the bright materials present in some craters like Occator, Haulani and Oxo that show different proportions of the components of the mixture [8]. However, the distribution of the band depths are not always linked to morphological structures. The retrieved mineralogy and composition indicates pervasive aqueous alteration of the surface, processes that are expected to be favored on large bodies like Ceres [9]. Furthermore, Ceres' low density

  7. 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

  8. Chemical Composition and Size Distributions of Coastal Aerosols Observed on the U.S. East Coast

    NASA Astrophysics Data System (ADS)

    Xia, L.; Song, F.; Jusino-Atresino, R.; Thuman, C.; Gao, Y.

    2008-12-01

    Aerosol input is an important source of certain limiting nutrients, such as iron, for phytoplankton growth in several large oceanic regions. As the efficiency of biological uptake of nutrients may depend on the aerosol properties, a better knowledge of aerosol properties is critically important. Characterizing aerosols over the coastal ocean needs special attention, because the properties of aerosols could be altered by many anthropogenic processes in this land-ocean transition zone before they are transported over the remote ocean. The goal of this experiment was to examine aerosol properties, in particular chemical composition, particle-size distributions and iron solubility, over the US Eastern Seaboard, an important boundary for the transport of continental substances from North America to the North Atlantic Ocean. Our field sampling site was located at Tuckerton (39°N, 74°W) on the southern New Jersey coast. Fourteen sets of High-Volume aerosol samples and three sets of size segregated aerosol samples by a 10-stage MOUDI impactor were collected during 2007 and 2008. The ICP-MS methodology was used to analyze aerosol samples for the concentrations of thirteen trace elements: Al, Fe, Mn, Sc, Cd, Pb, Sb, Ni, Co, Cr, Cu, Zn and V. The IC procedures were applied to determine five cations (sodium, ammonium, potassium, magnesium and calcium) and eleven anions (fluoride, acetate, propionate, formate, MSA, chloride, nitrate, succinate, malonate, sulfate and oxalate). The UV spectrometry was employed for the determination of iron solubility. Preliminary results suggest three major sources of aerosols: anthropogenic, crustal and marine. At this location, the concentrations of iron (II) ranged from 2.8 to 29ng m-3, accounting for ~20% of the total iron. The iron concentrations at this coastal site were substantially lower than those observed in Newark, an urban site in northern NJ. High concentrations of iron (II) were associated with both fine and coarse aerosol

  9. The Energy-Dependent Position of the IBEX Ribbon Due to the Solar Wind Structure

    NASA Astrophysics Data System (ADS)

    Swaczyna, Paweł; Bzowski, Maciej; Sokół, Justyna M.

    2016-08-01

    Observations of energetic neutral atoms (ENAs) allow for remote studies of the condition of plasma in the heliosphere and the neighboring local interstellar medium. The first results from the Interstellar Boundary Explorer (IBEX) revealed an arc-like enhancement of the ENA intensity in the sky, known as the ribbon. The ribbon was not expected from the heliospheric models prior to the launch of IBEX. One proposed explanation for the ribbon is the mechanism of secondary ENA emission. The ribbon reveals energy-dependent structure in the relative intensity along its circumference and in its position. That is, the geometric center of the ribbon varies systematically by about 10° in the energy range 0.7–4.3 keV. Here, we show by analytical modeling that this effect is a consequence of the helio-latitudinal structure of the solar wind reflected in the secondary ENAs. Along with a recently measured distance to the ribbon’s source just beyond the heliopause, our findings support the connection of the ribbon with the local interstellar magnetic field by the mechanism of secondary ENA emission. However, the magnitude of the center shift in the highest IBEX energy channel is much larger in the observations than expected from the modeling. This may be due to another, not currently recognized, process of ENA generation.

  10. Composition.

    ERIC Educational Resources Information Center

    Nemanich, Donald, Ed.

    1974-01-01

    The articles in this special issue of the "Illinois English Bulletin" concern the state of composition instruction at the secondary and college levels. The titles and authors are "Monologues or Dialogues? A Plea for Literacy" by Dr. Alfred J. Lindsey, "Teaching Composition: Curiouser and Curiouser" by Denny Brandon, and "Teaching Writing to High…

  11. The Energy Dependence of GRB Minimum Variability Timescales

    NASA Astrophysics Data System (ADS)

    Golkhou, V. Zach; Butler, Nathaniel R.; Littlejohns, Owen M.

    2015-10-01

    We constrain the minimum variability timescales for 938 gamma-ray bursts (GRBs) observed by the Fermi/Gamma-ray Burst Monitor instrument prior to 2012 July 11. The tightest constraints on progenitor radii derived from these timescales are obtained from light curves in the hardest energy channel. In the softer bands—or from measurements of the same GRBs in the hard X-rays from Swift—we show that variability timescales tend to be a factor of two to three longer. Applying a survival analysis to account for detections and upper limits, we find median minimum timescale in the rest frame for long-duration and short-duration GRBs of 45 and 10 ms, respectively. Less than 10% of GRBs show evidence for variability on timescales below 2 ms. These shortest timescales require Lorentz factors ≳ 400 and imply typical emission radii R≈ 1× {10}14 cm for long-duration GRBs and R≈ 3× {10}13 cm for short-duration GRBs. We discuss implications for the GRB fireball model and investigate whether or not GRB minimum timescales evolve with cosmic time.

  12. Beam energy dependence of the viscous damping of anisotropic flow

    NASA Astrophysics Data System (ADS)

    Lacey, Roy

    2013-10-01

    The flow harmonics v2 , 3 for charged hadrons, are studied for a broad range of centrality selections and beam collision energies in Au+Au (√{sNN} = 7 . 7 - 200 GeV) and Pb+Pb (√{sNN} = 2 . 76 TeV) collisions. They validate the characteristic signature expected for the system size dependence of viscous damping at each collision energy studied. The extracted viscous coefficients, that encode the magnitude of the ratio of shear viscosity to entropy density η / s , are observed to decrease to an apparent minimum as the collision energy is increased from √{sNN} = 7 . 7 to approximately 62.4 GeV; thereafter, they show a slow increase with √{sNN} up to 2.76 TeV. This pattern of viscous damping provides the first experimental constraint for η / s in the temperature-baryon chemical potential (T ,μB) plane, and could be an initial indication for decay trajectories which lie close to the critical end point in the phase diagram for nuclear matter. This research is supported by the US DOE under contract DE-FG02-87ER40331.A008.

  13. Excitation energy dependent Raman spectrum of MoSe2

    PubMed Central

    Nam, Dahyun; Lee, Jae-Ung; Cheong, Hyeonsik

    2015-01-01

    Raman investigation of MoSe2 was carried out with eight different excitation energies. Seven peaks, including E1g, A1g, E2g1, and A2u2 peaks are observed in the range of 100–400 cm−1. The phonon modes are assigned by comparing the peak positions with theoretical calculations. The intensities of the peaks are enhanced at different excitation energies through resonance with different optical transitions. The A1g mode is enhanced at 1.58 and 3.82 eV, which are near the A exciton energy and the band-to-band transition between higher energy bands, respectively. The E2g1 mode is strongly enhanced with respect to the A1g mode for the 2.71- and 2.81-eV excitations, which are close to the C exciton energy. The different enhancements of the A1g and E2g1 modes are explained in terms of the symmetries of the exciton states and the exciton-phonon coupling. Other smaller peaks including E1g and A2u2 are forbidden but appear due to the resonance effect near optical transition energies. PMID:26601614

  14. Surface-Energy Dependent Contact Activation of Blood Factor XII

    PubMed Central

    Golas, Avantika; Parhi, Purnendu; Dimachkie, Ziad O.; Siedlecki, Christopher A.; Vogler, Erwin A.

    2009-01-01

    Contact activation of blood factor XII (FXII, Hageman factor) in neat-buffer solution exhibits a parabolic profile when scaled as a function of silanized-glass-particle activator surface energy (measured as advancing water adhesion tension τao=γlvocosθ in dyne/cm, where γlvo is water interfacial tension in dyne/cm and θ is the advancing contact angle). Nearly equal activation is observed at the extremes of activator water-wetting properties −36<τao<72 dyne/cm (0° ≤ θ < 120°), falling sharply through a broad minimum within the 20<τao<40 dyne/cm (55° < θ < 75°) range over which activation yield (putatively FXIIa) rises just above detection limits. Activation is very rapid upon contact with all activators tested and did not significantly vary over 30 minutes of continuous FXII-procoagulant contact. Results suggest that materials falling within the 20<τao<40 dyne/cm surface-energy range should exhibit minimal activation of blood-plasma coagulation through the intrinsic pathway. Surface chemistries falling within this range are, however, a perplexingly difficult target for surface engineering because of the critical balance that must be struck between hydrophobicity and hydrophilicity. Results are interpreted within the context of blood plasma coagulation and the role of water and proteins at procoagulant surfaces. PMID:19892397

  15. Neutron energy-dependent initial DNA damage and chromosomal exchange.

    PubMed

    Tanaka, K; Gajendiran, N; Endo, S; Komatsu, K; Hoshi, M; Kamada, N

    1999-12-01

    This study was undertaken to investigate the biological effect of monoenergetic neutrons on human lymphocyte DNA and chromosomes. Monoenergetic neutrons of 2.3, 1.0, 0.79, 0.57, 0.37 and 0.186 MeV were generated, and 252Cf neutrons and 60Co gamma-rays were also used for comparison. Biological effect was evaluated two ways. The RBE values with the comet assay were estimated as 6.3 and 5.4 at 0.37 MeV and 0.57 MeV relative to that of 60Co gamma-rays, and chromosome aberration rates were also observed in these different levels of monoenergetic neutrons. The yield of chromosome aberrations per unit dose was high at lower neutron energies with a gradual decline with 0.186 MeV neutron energy. The RBE was increased to 10.7 at 0.57 MeV from 3.9 at 252Cf neutrons and reached 16.4 as the highest RBE at 0.37 MeV, but the value decreased to 11.2 at 0.186 MeV. The response patterns of initial DNA damage and chromosome exchange were quite similar to that of LET. These results show that the intensity of DNA damage and chromosomal exchange is LET dependent. RBE of low energy neutrons is higher than that of fission neutrons. Low energy neutrons containing Hiroshima atomic bomb radiation may have created a significantly higher incidence of biological effect in atomic bomb survivors. PMID:10804992

  16. Major-Element Compositional Diversity Observed by ChemCam Along the MSL Traverse: The First Three Years

    NASA Astrophysics Data System (ADS)

    Wiens, R. C.; Mangold, N.; Maurice, S.; Blaney, D. L.; Clegg, S. M.; Gasda, P. J.; Frydenvang, J.; Gasnault, O.; Forni, O.; Cousin, A.; Lasue, J.; Lanza, N.; Anderson, R. B.; Sautter, V.; Bridges, J.; Le Deit, L.; Nachon, M.; Rapin, W.; Meslin, P. Y.; Newsom, H. E.; Clark, B. C.; Vaniman, D. T.; Bridges, N.; Herkenhoff, K. E.; Ehlmann, B. L.; Dyar, M. D.; Fisk, M. R.; Francis, R.; Leveille, R. J.; Johnson, J. R.; Melikechi, N.; Jackson, R.; Fabre, C.; Payré, V.; Grotzinger, J. P.; Vasavada, A. R.; Crisp, J. A.

    2015-12-01

    ChemCam on Curiosity has used LIBS to obtain elemental compositions of >6000 target points at distances to 7.4 m from the rover. Observations include igneous clasts, sediments, diagenetic features, and other details often not accessible by the rover arm. A major re-calibration was recently completed using >350 standards. This significantly improved the accuracies of mineral end-members including plag-feldspars, hi-Si compositions, oxide grains, Mg-rich end-members (presumably Mg saponites; not yet confirmed by CheMin), and Mg and Ca sulfates. Here we draw conclusions from the overall compositional distributions observed in Gale crater from landing until the present using the new calibration. Observations from Bradbury Rise (sols 0-53, 326-520) show a scattering of compositions toward mineral end-members from igneous clasts and pebbles transported from the crater rim. In contrast, Sheepbed mudstones (first drill location; sols 126-300) form a tight cluster close to average Mars composition. The nearby Shaler fluvial sandstone outcrop (sols 306-325)--the first outcrop of potential deltaic foreset beds--shows K enrichment. This enrichment reaches a peak of 6 wt % K2O (sol 625) in the Mt. Remarkable member of the Kimberley formation, Kimberley being a drill location flanked by foreset beds 7 km SW of Shaler. The Pahrump outcrop (sols 753-919)—first observed material of the Murray formation at Mt. Sharp's base—shows lower Mg, higher Si, and much higher Al, consistent with stronger alteration. Further along the traverse ChemCam discovered an outcrop of light-toned Murray formation rock (sols 992 on) of nearly pure SiO2+TiO2. Overall, the ChemCam database points to a very strong diversity of inputs and alteration processes within a relatively short distance within Gale. Igneous compositions: while Jake Matijevic, a float analyzed early by APXS, appeared nepheline normative, no clear nepheline has been found by ChemCam. Additionally, despite the significant number of

  17. A composite indicator for assessing habitat quality of riparian forests derived from Earth observation data

    NASA Astrophysics Data System (ADS)

    Riedler, Barbara; Pernkopf, Lena; Strasser, Thomas; Lang, Stefan; Smith, Geoff

    2015-05-01

    Riparian forests are precious, complex habitats fostering high biodiversity where effective monitoring of habitat quality is particularly important. We present a composite indicator, referred to as Riparian Forest composite Indicator: focus on Structure (RFI_S), for the assessment of habitat quality and identification of 'hot-spot' areas where conservation actions need to be taken. The RFI_S is composed of seven indicators derived from very high resolution (VHR) satellite imagery and LiDAR data, calculated on patch level. These indicators assess four important attributes of riparian forest quality: (1) tree species composition, (2) vertical forest structure, (3) horizontal forest structure and (4) water regime. For the aggregation of the RFI_S, two different weighting schemes, expert-based and statistical weighting, are applied. Forest patches with high cumulative RFI_S values represent patches of good habitat quality. These patches are primarily found along water bodies, reflecting the importance of water bodies for the structural complexity, an optimum water regime and tree species composition. For forest patches of low habitat quality the RFI_S helps to design suitable measures to improve habitat quality status through its decomposability into the underlying indicators. A sensitivity analysis to test the robustness of the RFI_S shows that the indicator variance in terrain roughness has the strongest influence on the composite indicator. Finally, a comparison with an existing expert-based map on conservation status reveals the potential of a complementary quantitative assessment of habitat quality in the study site. We hence conclude that the RFI_S has a high capability to support sustainable forest management complementing regularly gathered in situ data.

  18. Energy dependence of mass, charge, isotopic, and energy distributions in neutron-induced fission of 235U and 239Pu

    NASA Astrophysics Data System (ADS)

    Pasca, H.; Andreev, A. V.; Adamian, G. G.; Antonenko, N. V.; Kim, Y.

    2016-05-01

    The mass, charge, isotopic, and kinetic-energy distributions of fission fragments are studied within an improved scission-point statistical model in the reactions 235U+n and 239Pu+n at different energies of the incident neutron. The charge and mass distributions of the electromagnetic- and neutron-induced fission of 214,218Ra, 230,232,238U are also shown. The available experimental data are well reproduced and the energy-dependencies of the observable characteristics of fission are predicted for future experiments.

  19. 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

  20. Characterizing the spatio-temporal and energy-dependent response of riometer absorption to particle precipitation

    NASA Astrophysics Data System (ADS)

    Kellerman, Adam; Makarevich, Roman; Spanswick, Emma; Donovan, Eric; Shprits, Yuri

    2016-07-01

    Energetic electrons in the 10's of keV range precipitate to the upper D- and lower E-region ionosphere, and are responsible for enhanced ionization. The same particles are important in the inner magnetosphere, as they provide a source of energy for waves, and thus relate to relativistic electron enhancements in Earth's radiation belts.In situ observations of plasma populations and waves are usually limited to a single point, which complicates temporal and spatial analysis. Also, the lifespan of satellite missions is often limited to several years which does not allow one to infer long-term climatology of particle precipitation, important for affecting ionospheric conditions at high latitudes. Multi-point remote sensing of the ionospheric plasma conditions can provide a global view of both ionospheric and magnetospheric conditions, and the coupling between magnetospheric and ionospheric phenomena can be examined on time-scales that allow comprehensive statistical analysis. In this study we utilize multi-point riometer measurements in conjunction with in situ satellite data, and physics-based modeling to investigate the spatio-temporal and energy-dependent response of riometer absorption. Quantifying this relationship may be a key to future advancements in our understanding of the complex D-region ionosphere, and may lead to enhanced specification of auroral precipitation both during individual events and over climatological time-scales.

  1. Composition and evolution of the continental crust as suggested by seismic observations

    USGS Publications Warehouse

    Pakiser, L.C.; Robinson, R.

    1966-01-01

    The average composition of the continental crust is more mafic than hitherto supposed. The conterminous United States can be divided, on the basis of seismic structure, into ten regions. The seven western and the three eastern regions can be termed western and eastern superprovinces. Seismic studies show that the crust is thinner and more silicic in tectonically active regions (western superprovince - average crustal thickness 34 km), than in stable regions (eastern superprovince - average crustal thickness 44 km). Mafic rocks are estimated to average 55% of the continental crust: 45% in the western and 59% in the eastern superprovince. These results express quantitatively the ideas expressed qualitatively by Pakiser and Zietz (1965). The computations of percentages of major oxides in the crust associate seismic velocities with rock compositions. ?? 1956.

  2. The atmospheric composition geostationary satellite constellation for air quality and climate science: Evaluating performance with Observation System Simulation Experiments

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    Current satellite observations of tropospheric composition made from low Earth orbit provide at best one or two measurements each day at any given location. 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 GEO 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. We discuss the requirements on measurement simulation, chemical transport modeling, and data assimilation for a successful OSSE infrastructure. 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 is being expanded to other chemical pollutants, currently produces multispectral retrievals and captures realistic scene-dependent variation in measurement vertical sensitivity and cloud cover. We use the DART Ensemble Adjustment Kalman Filter to assimilate the simulated observations in a CAM-Chem global chemistry-climate model Control Run. The impact of observing over each region is evaluated using data

  3. Latitudinal and Energy Dependence of Energetic Neutral Atom Spectral Indices Measured by the Interstellar Boundary Explorer

    NASA Astrophysics Data System (ADS)

    Desai, M. I.; Allegrini, F.; Dayeh, M. A.; Funsten, H.; Heerikhuisen, J.; McComas, D. J.; Fuselier, S. A.; Pogorelov, N.; Schwadron, N. A.; Zank, G. P.; Zirnstein, E. J.

    2015-04-01

    We investigate the latitudinal and energy dependence of the globally distributed 0.5-6 keV energetic neutral atom (ENA) spectra measured by the Interstellar Boundary Explorer (IBEX) during the first 3 yrs of the mission. Our results are: (1) the ENA spectral indices at the two lowest energies (0.89 and 1.47 keV) exhibit no clear trend with ecliptic latitude θ, while those at ˜2.29 and ˜3.41 keV exhibit a clear latitudinal pattern; flatter spectra occur above 60° latitude and steeper spectra occur ±30° of the equator. (2) The latitudinal dependence of the spectral indices at different energies can be represented by the cosine function γ ={{a}0}+{{a}1}cos ({{a}2}θ ) with unique offsets, amplitudes, and phase angles; the higher energy ENA indices transition to successively larger amplitudes within ±45° of the equator. Our results confirm the previously reported latitudinal organization of the ENA spectra and their remarkable similarity to that of the solar wind (SW) speed observed by Ulysses in the inner heliosphere. While earlier studies showed that the ˜0.5-6 keV globally distributed ENA spectral indices could be represented as single power laws over much of the sky, our new results indicate that this is an over-simplification because the spectral indices have an energy and latitude dependence. This dependence is an important factor that must be taken into consideration by models and simulations that seek to map the IBEX ENA observations back to the latitudinal profile of the SW speed structure observed in the inner heliosphere.

  4. Deep scattering layer migration and composition: observations from a diving saucer.

    PubMed

    Barham, E G

    1966-03-18

    The distribution of a myctophid fish and physonect siphonophores observed during dives in the Soucoupe off Baja California closely correlates with scattering layers recorded simultaneously with a 12-kcy/sec echo sounder. These organisms were observed while they were migrating vertically, and at their night and daytime levels. They are capable of rapid, extensive changes in depth. PMID:17817303

  5. Composites

    SciTech Connect

    Chou, T.; McCullough, R.L.; Pipes, R.B.

    1986-10-01

    The degree of control over material properties that is typified by hybrid composites is transforming engineering design. In part because homogeneous materials such as metals and alloys do not offer comparable control, specifying a material and designing a component have traditionally taken place separately. As composites begin to replace traditional materials in fields and such as aerospace, component design and the specification of a material are merging and becoming aspects of a single process. The controllable microstructure of a composite allows it to be tailored to match the distribution of stresses to which it will be subject. At the same time components must come to reflect the distinctive nature of composites: their directional properties and the intricate forms they can be given through processes such as injection molding, filament winding and three-dimensional weaving. The complexity inherent in conceiving components and their materials at the same time suggests engineering design will grow increasingly dependent on computers and multidisciplinary teams. Such an approach will harness the full potential of composites for the technologies of the future. 10 figures.

  6. Observation of the initiation and progression of damage in compressively loaded composite plates containing a cutout

    NASA Technical Reports Server (NTRS)

    Waas, A.; Babcock, C., Jr.

    1986-01-01

    A series of experiments was carried out to determine the mechanism of failure in compressively loaded laminated plates with a circular cutout. Real time holographic interferometry and photomicrography are used to observe the progression of failure. These observations together with post experiment plate sectioning and deplying for interior damage observation provide useful information for modelling the failure process. It is revealed that the failure is initiated as a localised instability in the zero layers, at the hole surface. With increasing load extensive delamination cracking is observed. The progression of failure is by growth of these delaminations induced by delamination buckling. Upon reaching a critical state, catastrophic failure of the plate is observed. The levels of applied load and the rate at which these events occur depend on the plate stacking sequence.

  7. Reconcile Mantle Dynamic Models with Compositionally Distinct and Stable LLSVPs with the Observations of the Geoid and Dynamic Topography

    NASA Astrophysics Data System (ADS)

    Liu, X.; Zhong, S.

    2015-12-01

    The geoid has been well explained in mantle flow models with the buoyancy inferred from seismic models that in turn place constraints on mantle viscosity structure (e.g., Hager & Richards, 1989). These models often assume a whole-mantle convection with uniform composition and 1-D viscosity. However, seismic and geochemical observations suggest possible existence of chemically distinct piles under Africa and Pacific which extends hundreds of kilometers above the CMB (i.e., LLSVPs). As compositional heterogeneity would significantly alter the interpretation of seismic anomalies as buoyancy structure, important questions are whether a thermochemical mantle model based on seismic velocity anomalies can reconcile the geoid and how this may impact inference of mantle viscosity structure. In this study, we formulate mantle flow models that use buoyancy derived from seismic model S40RTS (Ritsema et al., 2011), assuming that the LLSVPs are stable with negative buoyancy. The models use temperature-, depth- and composition-dependent viscosity and are computed for the geoid, dynamic topography and flow velocity using CitcomS. Seismic anomalies are converted to buoyancy using thermal conversion factor cT for the whole mantle materials and composition conversion factor cc for the chemical piles defined as the domains with seismic slow anomaly <-0.5% and a maximum height of 500 km. The temperature-dependence viscosity gives rise to 3 orders of magnitude variations in viscosity, and horizontally averaged viscosity profile is consistent with the inferred 1-D viscosity from the geoid. The viscosity in the chemical piles is further reduced by a factor of Cvisc to represent the compositional effect. We measure the stability of the chemical piles by the RMS vertical velocities on the piles boundary. Our preferred thermochemical models with stable chemical piles reach similar variance reduction of geoid at ~64% to that for the uniform composition models. In the preferred model, cT is ~0

  8. 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.

  9. Energy dependent time delays of kHz oscillations due to thermal Comptonization

    NASA Astrophysics Data System (ADS)

    Kumar, Nagendra; Misra, Ranjeev

    2014-12-01

    We study the energy dependent photon variability from a thermal Comptonizing plasma that is oscillating at kHz frequencies. In particular, we solve the linearized time-dependent Kompaneets equation and consider the oscillatory perturbation to be either in the soft photon source or in the heating rate of the plasma. For each case, we self consistently consider the energy balance of the plasma and the soft photon source. The model incorporates the possibility of a fraction of the Comptonized photons impinging back into the soft photon source. We find that when the oscillation is due to the soft photon source, the variation of the fractional root mean sqaure (rms) is nearly constant with energy and the time-lags are hard. However, for the case when the oscillation is due to variation in the heating rate of the corona, and when a significant fraction of the photons impinge back into the soft photon source, the rms increases with energy and the time-lags are soft. As an example, we compare the results with the ˜850 Hz oscillation observed on 1996 March 3 for 4U 1608-52 and show that both the observed soft time-lags as well as the rms versus energy can be well described by such a model where the size of the Comptonizing plasma is ˜1 km. Thus, modelling of the time-lags as due to Comptonization delays, can provide tight constraints on the size and geometry of the system. Detailed analysis would require well-constrained spectral parameters.

  10. Structure and composition of the distant lunar exosphere: Constraints from ARTEMIS observations of ion acceleration in time-varying fields

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

    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.

  11. Observation of tunable nonlinear effects in an analogue of superconducting composite right/left hand filter.

    PubMed

    Liu, Haiwen; Lei, Jiuhuai; Jiang, Hao; Guan, Xuehui; Ji, Laiyun; Ma, Zhewang

    2015-01-01

    Artificial structures with negative permittivity or permeability have attracted significant attention in the science community because they provide a pathway for obtaining exotic electromagnetic properties not found in natural materials. At the moment, the great challenge of these artificial structures in microwave frequency exhibits a relatively large loss. It is well-known that superconducting thin films have extremely low surface resistance. Hence, it is a good candidate to resolve this constraint. Besides, the reported artificial structures with negative permittivity or permeability are mainly focusing on linear regime of wave propagation. However, any future effort in creating tunable structures would require knowledge of nonlinear properties. In this work, a tunable superconducting filter with composite right/left-hand transmission property is proposed and fabricated. Its nonlinear effects on temperature and power are studied by theoretical analysis and experiments. PMID:26442447

  12. Airborne observations of the composition of the 1992 tropical stratosphere by FTIR solar absorption spectrometry

    NASA Technical Reports Server (NTRS)

    Toon, G. C.; Blavier, J.-F.; Solario, J. N.; Szeto, J. T.

    1993-01-01

    Vertical column measurements of the gaseous composition of the tropical stratosphere were made from the NASA DC-8 aircraft early in 1992. As anticipated, the burdens of the stratospheric source gases (e.g., O3, HF, HCl, ClNO3, HNO3) were reduced from their mid-latitude values due to increased uplift and photolysis. The tracers revealed considerably more uplift near the equator than the sub-tropics. For example, the HF burdens at +/- 20 deg latitude were nearly double those at 5 deg N. This, together with results obtained from other long-lived gases (e.g. N2O, CH4, CF2Cl2) indicates that volume mixing ratios found at 22 km altitude at mid-latitudes occurred at 26 km in the sub-tropics and at 30 km in the equatorial zone. This zone of uplift was symmetrical about the equator even though the sun was overhead at 20 deg S.

  13. Venus upper atmosphere neutral gas composition - First observations of the diurnal variations

    NASA Technical Reports Server (NTRS)

    Niemann, H. B.; Hartle, R. E.; Hedin, A. E.; Kasprzak, W. T.; Spencer, N. W.; Hunten, D. M.; Carignan, G. R.

    1979-01-01

    Measurements of the composition, temperature, and diurnal variations of the major neutral constituents in the thermosphere of Venus are being made with a quadrupole mass spectrometer on the Pioneer Venus Orbiter. Concentrations of carbon dioxide, carbon monoxide, molecular nitrogen, atomic oxygen, and helium are presented, in addition to an empirical model of the data. The concentrations of the heavy gases, carbon dioxide, carbon monoxide, and molecular nitrogen, rapidly decrease from the evening terminator toward the nightside; the concentration of atomic oxygen remains nearly constant and the helium concentration increases, an indication of a nightside bulge. The kinetic temperature inferred from scale heights drops rapidly from 230 K at the terminator to 130 K at a solar zenith angle of 120 deg, and to 112 K at the antisolar point.

  14. In situ observation and measurement of composites subjected to extremely high temperature

    NASA Astrophysics Data System (ADS)

    Fang, Xufei; Yu, Helong; Zhang, Guobing; Su, Hengqiang; Tang, Hongxiang; Feng, Xue

    2014-03-01

    In this work, we develop an instrument to study the ablation and oxidation process of materials such as C/SiC (carbon fiber reinforced silicon carbide composites) and ultra-high temperature ceramic in extremely high temperature environment. The instrument is integrated with high speed cameras with filtering lens, infrared thermometers and water vapor generator for image capture, temperature measurement, and humid atmosphere, respectively. The ablation process and thermal shock as well as the temperature on both sides of the specimen can be in situ monitored. The results show clearly the dynamic ablation and liquid oxide flowing. In addition, we develop an algorithm for the post-processing of the captured images to obtain the deformation of the specimens, in order to better understand the behavior of the specimen subjected to high temperature.

  15. Observations of low-energy plasma composition from the ISEE-1 and SCATHA satellites

    NASA Technical Reports Server (NTRS)

    Horwitz, J. L.; Chappell, C. R.; Reasoner, D. L.; Craven, P. D.; Green, J. L.; Baugher, C. R.

    1983-01-01

    This brief review is concerned with some of the initial measurements of low-energy ion properties conducted with the aid of ion composition detectors aboard the ISEE-1 and SCATHA satellites. ISEE-1 was launched in October 1977 into a highly elliptical orbit, while SCATHA was launched in January 1979 into a near geosynchronous orbit. Attention is given to the origin of low-energy plasma, the energization of ionospheric ions, the transport of ionospheric ions, and the loss of low-energy plasma from the magnetosphere. According to results obtained during the past several years, including the present ISEE-1 and SCATHA results, there are significant, and occasionally dominant, concentrations of He(+) and O(+) in various locations within the magnetosphere.

  16. Observation of tunable nonlinear effects in an analogue of superconducting composite right/left hand filter

    PubMed Central

    Liu, Haiwen; Lei, Jiuhuai; Jiang, Hao; Guan, Xuehui; Ji, Laiyun; Ma, Zhewang

    2015-01-01

    Artificial structures with negative permittivity or permeability have attracted significant attention in the science community because they provide a pathway for obtaining exotic electromagnetic properties not found in natural materials. At the moment, the great challenge of these artificial structures in microwave frequency exhibits a relatively large loss. It is well-known that superconducting thin films have extremely low surface resistance. Hence, it is a good candidate to resolve this constraint. Besides, the reported artificial structures with negative permittivity or permeability are mainly focusing on linear regime of wave propagation. However, any future effort in creating tunable structures would require knowledge of nonlinear properties. In this work, a tunable superconducting filter with composite right/left-hand transmission property is proposed and fabricated. Its nonlinear effects on temperature and power are studied by theoretical analysis and experiments. PMID:26442447

  17. The influence of body composition on therapeutic hypothermia: a prospective observational study of patients after cardiac arrest

    PubMed Central

    Jimmink, Joost J; Binnekade, Jan M; Paulus, Frederique; Mathus-Vliegen, Elisebeth MH; Schultz, Marcus J; Vroom, Margreeth B

    2008-01-01

    Introduction Patients after out-of-hospital cardiac arrest (OHCA) benefit from therapeutic hypothermia for 24 hours. The time needed to reach hypothermia (target temperature of 32°C to 34°C) varies widely. In this study, we explore the relation between measures of body composition and the time needed to reach target temperature with hypothermia. Method We conducted a prospective observational study in patients treated with hypothermia after OHCA. Data collected included weight and height, body composition by anthropometric measures and by single-frequency body impedance, and waist-to-hip ratio. Analysis of concordance between impedance and anthropometric measures and hazard ratios of achieving target temperature (event) corrected for different body composition measures. Results Twenty-seven patients were included. The median (interquartile range) time to reach target temperature after admission to the intensive care unit was 191 (105 to 382) minutes. Intraclass correlation for total body fat (TBF) measures was 0.94 (95% confidence interval [CI] 0.89 to 0.97). Only TBF percentage (anthropometrics by the Durnin's table) appeared to be associated with time to reach target temperature: 0.93 (95% CI 0.87 to 0.99; P = 0.03). Conclusion The body composition measures from single-frequency impedance and anthropometrics appear to be very concordant. Only TBF percentage (anthropometrics) showed a significant but clinically irrelevant influence on time needed to achieve target temperature with hypothermia. We conclude that there are no indications to adjust current cooling practice toward the body composition of patients. PMID:18616810

  18. Energy dependence of breakup cross sections of the halo nucleus {sup 8}B and effective interactions

    SciTech Connect

    Bertulani, C.A.; Lotti, P.; Sagawa, H.

    1998-01-01

    We study the energy dependence of the cross sections for nucleon removal of {sup 8}B projectiles. It is shown that the Glauber model calculations with nucleon-nucleon t-matrix reproduce well the energy dependence of the breakup cross sections of {sup 8}B. A distorted wave Born approximation (DWBA) model for the breakup cross section is also proposed and results are compared with those of the Glauber model. We show that to obtain an agreement between the DWBA calculations, the Glauber formalism, and the experimental data, it is necessary to modify the energy behavior of the effective interaction. In particular, the breakup potential has a quite different energy dependence than the strong absorption potential. {copyright} {ital 1998} {ital The American Physical Society}

  19. Connecting the dots: Investigating planet formation and composition through observations of carbon and oxygen species in stars, disks, and planets

    NASA Astrophysics Data System (ADS)

    Teske, Johanna Kavanagh

    What physical processes and sources of material contribute to exoplanet compositions? Specifically, what roles do the protoplanetary disk composition and structure, and host star abundances play in the different stages of planet formation? In this thesis, beginning with a brief literature review in Chapter 2, I trace oxygen and carbon species through these stages to inform how, when, and where planets form. In Chapter 3 I describe a study of the molecular emission from the warm inner disks of T Tauri stars, where terrestrial planets likely form. I report moderate correlations between HCN emission strength and both stellar accretion rate (measured from UV or optical excess emission associated with accretion) and X-ray luminosity. These correlations point towards accretion related processes being an important source of disk atmosphere heating, and suggests that efficient H2O formation and/or UV dissociation of N2 (both also associated with higher stellar accretion rates) may aid in the production of HCN. Studies following mine have further connected the abundance of HCN versus H2O to the growth and migration of planetesimals in the disk, which helps control the formation of both giant and terrestrial planets. I shift to an already-formed exoplanet in Chapter 4, where I present optical photometry of the best-observed transiting super-Earth GJ 1214b with the goal of constraining the short-wavelength slope of its transmission spectrum. Most previous observations suggested a flat spectrum from the near-IR to the optical, corresponding to a low-scale-height, high-molecular-weight atmosphere. My observations are in general agreement with these findings, keeping the "door open" for a H2O-rich atmosphere for GJ 1214b, which other published g-band observations appeared to contradict. Chapters 5-7 of my thesis focus on measuring stellar abundances, particularly C/O ratios, in transiting (mostly) hot Jupiter exoplanet host stars from high resolution optical spectroscopy. Host

  20. Classroom Composition and Measured Teacher Performance: What Do Teacher Observation Scores Really Measure?

    ERIC Educational Resources Information Center

    Steinberg, Matthew P.; Garrett, Rachel

    2016-01-01

    As states and districts implement more rigorous teacher evaluation systems, measures of teacher performance are increasingly being used to support instruction and inform retention decisions. Classroom observations take a central role in these systems, accounting for the majority of teacher ratings upon which accountability decisions are based.…

  1. Temporal Variation of Chemical Composition of Comet C/2007 N3 (lulin) Observed in the Near-infrared Wavelength Region

    NASA Astrophysics Data System (ADS)

    Kobayashi, Hitomi; Kawakita, H.; Dello Russo, N.; Vervack, R. J.; Weaver, H. A.; Biver, N.; Bockelee-Morvan, D.; Crovisier, J.

    2009-09-01

    Oort Cloud comet C/2007 N3 (Lulin) approached the Sun in February 2009. Its maximum brightness was about 4th magnitude in V-band. The high productivity of Lulin provided the opportunity to measure chemical composition and monitor the overall volatile productivity of the comet over time. High dispersion near-infrared spectroscopic observations of C/2007 N3 (Lulin) were carried out in August 2008 and January through March 2009 by three different telescopes/instruments atop Mauna Kea, Hawaii: Subaru/IRCS, Keck II/NIRSPEC and IRTF/CSHELL. The spectral resolving powers are 10,000 for IRCS and 25,000 for both NIRSPEC and CSHELL. We present the composition of organic volatiles and the rotational and nuclear spin temperature of water in Lulin. We sampled H2O, OH, HCN, C2H2, NH3, CH4, C2H6, CO, CH3OH, and H2CO in our observations. The temporal coverage of our observations allowed a search for chemical heterogeneity within the nucleus of Lulin, and we discuss the absolute and relative production rates of these species with time and compare the chemistry of Lulin to other comets. The nuclear spin temperature of H2O will also be compared to derived values from other comets.

  2. 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.

  3. Composites

    NASA Astrophysics Data System (ADS)

    Taylor, John G.

    The Composites market is arguably the most challenging and profitable market for phenolic resins aside from electronics. The variety of products and processes encountered creates the challenges, and the demand for high performance in critical operations brings value. Phenolic composite materials are rendered into a wide range of components to supply a diverse and fragmented commercial base that includes customers in aerospace (Space Shuttle), aircraft (interiors and brakes), mass transit (interiors), defense (blast protection), marine, mine ducting, off-shore (ducts and grating) and infrastructure (architectural) to name a few. For example, phenolic resin is a critical adhesive in the manufacture of honeycomb sandwich panels. Various solvent and water based resins are described along with resin characteristics and the role of metal ions for enhanced thermal stability of the resin used to coat the honeycomb. Featured new developments include pultrusion of phenolic grating, success in RTM/VARTM fabricated parts, new ballistic developments for military vehicles and high char yield carbon-carbon composites along with many others. Additionally, global regional market resin volumes and sales are presented and compared with other thermosetting resin systems.

  4. Observations of fatigue crack initiation and damage growth in notched titanium matrix composites

    NASA Technical Reports Server (NTRS)

    Naik, Rajiv A.; Johnson, W. S.

    1991-01-01

    The purpose was to characterize damage initiation and growth in notched titanium matrix composites at room temperature. Double edge notched or center open hole SCS-6/Ti-15-3 specimens containing 0 deg plies or containing both 0 and 90 deg plies were fatigued. The specimens were tested in the as-fabricated (ASF) and in heat-treated conditions. A local strain criterion using unnotched specimen fatigue data was successful in predicting fatigue damage initiation. The initiation stress level was accurately predicted for both a double edge notched unidirectional specimen and a cross-plied center hole specimen. The fatigue produced long multiple cracks growing from the notches. These fatigue cracks were only in the matrix material and did not break the fibers in their path. The combination of matrix cracking and fiber/matrix debonding appears to greatly reduce the stress concentration around the notches. The laminates that were heat treated showed a different crack growth pattern. In the ASF specimens, matrix cracks had a more tortuous path and showed considerable more crack branching. For the same specimen geometry and cyclic stress, the (0/90/0) laminate with a hole had far superior fatigue resistance than the matrix only specimen with a hole.

  5. Observations of fatigue crack initiation and damage growth in notched titanium matrix composites

    NASA Technical Reports Server (NTRS)

    Naik, R. A.; Johnson, W. S.

    1990-01-01

    The purpose was to characterize damage initiation and growth in notched titanium matrix composites at room temperature. Double edge notched or center open hole SCS-6/Ti-15-3 specimens containing 0 deg plies or containing both 0 and 90 deg plies were fatigued. The specimens were tested in the as-fabricated (ASF) and in heat-treated conditions. A local strain criterion using unnotched specimen fatigue data was successful in predicting fatigue damage initiation. The initiation stress level was accurately predicted for both a double edge notched unidirectional specimen and a cross-plied center hole specimen. The fatigue produced long multiple cracks growing from the notches. These fatigue cracks were only in the matrix material and did not break the fibers in their path. The combination of matrix cracking and fiber/matrix debonding appears to greatly reduce the stress concentration around the notches. The laminates that were heat treated showed a different crack growth pattern. In the ASF specimens, matrix cracks had a more tortuous path and showed considerable more crack branching. For the same specimen geometry and cyclic stress, the (0/90/0) laminate with a hole had far superior fatigue resistance than the matrix only specimen with a hole.

  6. The energy dependence of quasi periodic oscillations in GRS 1915+105

    NASA Astrophysics Data System (ADS)

    Van Den Eijnden, Jakob; Ingram, Adam; Uttley, Phil

    2016-01-01

    Accreting stellar-mass black holes display quasi-periodic oscillations (QPOs) in their X-ray flux with a period that drifts from approximately 0.05 to 10 seconds. Since the oscillatory signal originates from the close proximity of the black hole, QPOs provide a diagnostic of the motion of matter in this region of extreme gravitational curvature. Here I present an analysis of the energy dependence of QPOs in the black hole binary GRS 1915+105. The QPO period in this black hole binary is known to be correlated with the observed energy band. To investigate this further, we extract light curves in two broad energy bands using archival data from the Rossi X-ray Timing Explorer, and apply a filter that separates the QPO from the coincident noise. The filtered light curves reveal that, in both energy bands, the modulation repeatedly rises and falls in amplitude in an envelope that typically lasts about five to ten QPO cycles. We find that, during each of these so-called coherence timescales, the phase difference between the two QPO light curves increases before resetting at the start of the next coherence time scale. This indicates that the oscillation in one energy band is genuinely faster than that in the other band, and puts interesting constraints on current QPO models. If the QPO originates from vertical general relativistic precession of the inner accretion flow, our result indicates that the inner regions of this flow precess slightly quicker than the outer regions, with the precession phase resetting after five to ten QPO cycles.

  7. Composition and stability of the condensate observed at the Viking Lander 2 site on Mars

    NASA Technical Reports Server (NTRS)

    Hart, H. M.; Jakosky, B. M.

    1986-01-01

    Surface energy balance and near-surface temperature data from the Viking Lander 2 site taken during the first winter that condensated were observed and analyzed to determine the relative stability of CO2 and H2O frosts. The CO2 frost stability is calculated with an equilibrium surface energy balance model, i.e., the total energy incident on a frost surface is compared with the blackbody energy emitted by the surface. The energy sources considered were IR emission from the atmosphere, sunlight, and the sensible heat flux from the atmosphere. H2O stability was examined as a function of buoyant diffusion and turbulent mixing processes which could remove saturated near-surface gases. The CO2 frost is found to be sufficiently unstable at the time the condensate was observed on the ground, so all CO2 ice deposited at night would boil away in a few hours of sunlight. CO2 ice would not form during a dust storm. Water frost would be stable during the condensate observations, since sublimation would occur at a rate below 1 micron/day. A stable winter thickness of 10 microns is projected for the water ice.

  8. Spatial Variability of Trace Gases During DISCOVER-AQ: Planning for Geostationary Observations of Atmospheric Composition

    NASA Technical Reports Server (NTRS)

    Follette-Cook, Melanie B.; Pickering, K.; Crawford, J.; Appel, W.; Diskin, G.; Fried, A.; Loughner, C.; Pfister, G.; Weinheimer, A.

    2015-01-01

    Results from an in-depth analysis of trace gas variability in MD indicated that the variability in this region was large enough to be observable by a TEMPO-like instrument. The variability observed in MD is relatively similar to the other three campaigns with a few exceptions: CO variability in CA was much higher than in the other regions; HCHO variability in CA and CO was much lower; MD showed the lowest variability in NO2All model simulations do a reasonable job simulating O3 variability. For CO, the CACO simulations largely under over estimate the variability in the observations. The variability in HCHO is underestimated for every campaign. NO2 variability is slightly overestimated in MD, more so in CO. The TX simulation underestimates the variability in each trace gas. This is most likely due to missing emissions sources (C. Loughner, manuscript in preparation).Future Work: Where reasonable, we will use these model outputs to further explore the resolvability from space of these key trace gases using analyses of tropospheric column amounts relative to satellite precision requirements, similar to Follette-Cook et al. (2015).

  9. Intermediate energy neutrons at WNR. Spin-isospin and energy dependence of the NN interaction and the nuclear response

    SciTech Connect

    Taddeucci, T.N.

    1995-02-01

    This report summarizes results of nuclear physics studies using intermediate energy (50-800 MeV) neutron probes carried out over the past five years using the Neutron Time-of-Flight (NTOF) Facility and Optically-Pumped Ion Source (OPPIS) at LAMPF and the `white` neutron source at the Weapons Neutron Research (WNR) facility. LAMPF did significant work in polarization transfer, while WNR took advantage of the wide neutron energy spectrum available to study energy dependent effects. The major focus of experiments with intermediate energy neutron probes for the next five years will be to explore fundamental details of the spin-isospin and energy dependence of the NN interaction and the nuclear response. To achieve this goal, the WNR white neutron source will be used for nucleon-nucleon and nucleon-nucleus interaction studies over a broad continuous range of incident neutron energy. Measurement of polarization observables using polarized targets or polarized beam should be possible, and will add an important extra dimension to these studies.

  10. Mean Thermal and Compositional Properties of Uranus from Combined Spitzer, ISO, Herschel and Ground-Based Observations

    NASA Astrophysics Data System (ADS)

    Orton, Glenn; Feuchtgruber, Helmut; Fletcher, Leigh; Moreno, Raphael; Moses, Julianne; Hofstadter, Mark; Lellouch, Emmanuel; Schaeffer, Jochem

    2013-04-01

    We derived models for the mean thermal structure and composition of the atmosphere of Uranus from a suite of spacecraft and ground-based observations. A family of models of the atmospheric temperature and composition derived from the Spitzer Infrared Spectrometer (IRS) data (Orton et al. 2013, submitted to Icarus) have been updated to include the significant influence of H2-H2 dimers on collision-induced absorption that was used to constrain the vertical temperature profile in the upper troposphere down to the 2-bar pressure level. IRS observations of H2 quadrupole lines provided additional constraints on temperatures in the lower stratosphere at pressures less than 100 mbar. We applied additional constraints on this family of models from Hershel PACS observations of HD (Feuchtgruber et al. 2013, Astron. & Astrophys. in press). We have also constrained the He/H2 ratio that characterizes the bulk composition of the atmosphere from previously unpublished observations by the ISO Short-Wavelength Spectrometer (SWS) and confirmed values originally derived by the Voyager IRIS and Radio Sub-System experiment (Conrath et al. 1987. J. Geophys. Res. 92, 15003). We have coupled observational constraints on the vertical distribution of CH4 in the stratosphere of Uranus with models for the vertical mixing that are consistent with the mixing ratios of hydrocarbons whose abundances are primarily influenced by dynamics rather than chemistry. Spitzer and Hershel data provide substantial constraints on the abundances and distributions of CH3, CH4, C2H2, C2H6, C3H4, C4H2, H2O and CO2. At millimeter wavelengths, strategic ground-based observations from the United Kingdom Infrared Telescope (UKIRT) and Caltech Submillimeter Observatory (CSO) atop Mauna Kea, Hawaii, provide evidence that an additional opacity source in Uranus is required besides (i) the H2 collision-induced and absorption, including significant dimer contributions, and (ii) the NH3 absorption that is consistent with the

  11. Investigating Chemical Compositions of Select Saturnian Satellites via Mosaicking of Cassini VIMS Observations.

    NASA Astrophysics Data System (ADS)

    Hosmer, Laura; Dalle Ore, C.; Mastrapa, R.; Speck, A.

    2012-01-01

    Cassini has collected data of many of Saturn's moons which provide information on the surface composition of the satellites and ultimately investigate their chemical and physical history. Mosaics are vital in analyzing the large amounts of data gathered from VIMS. Programs ENVI 4.8 and ISIS 3 were utilized and their results compared to determine optimum efficiency and output when creating mosaics. It was desirable to duplicate the cluster analysis of Mimas performed by Marzo [1] to definitively prove ISIS 3's capability to create mosaics identical to ENVI. Concerning the satellites of Saturn we were interested in searching for evidence of polycyclic aromatic hydrocarbons (PAHs) as well as CO2 via cluster analysis. Preliminary results of Mimas show that the outline of Hershel crater belongs to a different group than the immediate surroundings implicating a variation in the physical properties of the ice. Since the clustering was done focusing on a short wavelength range around the 1.5 micron water band the variation is most likely due to grain size differences as shown by Stephan et al (2005) in their study of Ganymede. The other intriguing feature outlined by the clustering of Mimas is a pattern on the side of the ring outlining the Hershel crater. The representative spectrum of this group shows an anomaly that could be due to contamination of minerals from an impact. Further analysis is necessary to confirm this preliminary result. The ultimate goal of our attempt at reproducing the mosaic independently (with ISIS3) and to repeat the cluster analysis is to investigate this intriguing result.

  12. Correlation of Structural Differences between Nafion/Polyaniline and Nafion/Polypyrrole Composite Membranes and Observed Transport Properties

    SciTech Connect

    Schwenzer, Birgit; Kim, Soowhan; Vijayakumar, M.; Yang, Zhenguo; Liu, Jun

    2011-04-15

    Polyaniline/Nafion and polypyrrole/Nafion composite membranes, prepared by chemical polymerization, are studied by infrared and nuclear magnetic resonance spectroscopy, and scanning electron microscopy. Differences in vanadium ion diffusion through the membranes and in the membranes’ area specific resistance are linked to analytical observations that polyaniline and polypyrrole interact differently with Nafion. Polypyrrole, a weakly basic polymer, binds less strongly to the sulfonic acid groups of the Nafion membrane, and thus the hydrophobic polymer aggregates in the center of the Nafion channel rather than on the hydrophilic side chains of Nafion that contain sulfonic acid groups. This results in a drastically elevated membrane resistance and an only slightly decreased vanadium ion permeation compared to a Nafion membrane. Polyaniline on the other hand is a strongly basic polymer, which forms along the sidewalls of the Nafion pores and on the membrane surface, binding tightly to the sulfonic acid groups of Nafion. This leads to a more effective reduction in vanadium ion transport across the polyaniline/Nafion membranes and the increase in membrane resistance is less severe. The performance of selected polypyrrole/Nafion composite membranes is tested in a static vanadium redox cell. Increased coulombic efficiency, compared to a cell employing Nafion, further confirms the reduced vanadium ion transport through the composite membranes.

  13. The volatile composition of comet 103P/Hartley 2 from ground-based radio observations

    NASA Astrophysics Data System (ADS)

    Gicquel, Adeline; Milam, S. N.; Remijan, A. J.; Chuang, Y.; Kuan, Y.; Coulson, I. M.; Villanueva, G.; Charnley, S. B.; Cordiner, M. M.

    2013-10-01

    103P/Hartley 2 (103P) is a Jupiter-family comet which has a short orbital period (6.5 years) and perihelion at 1.06 AU. 103P was discovered on 4 June 1984 by Malcolm Hartley at the Siding Spring Observatory and has been frequently observed over the 20 years following its discovery, both by ground-based and space telescopes. Observation from 1991 and 1997 indicated a maximum water production rate of 3 x 10^28 molecules/s. 103P passed perihelion on 28 October 2010 at q = 1.059 AU. It made an exceptional close approach to the Earth just before perihelion on 21 October 2010 at Δ = 0.12 AU. On UT 2010 November 4.58, the comet was visited by NASA’s EPOXI spacecraft with a flyby at 700 km. As part of an ongoing investigation to establish the contribution of the natal molecular cloud from which the solar system was formed to primitive materials and comets, we have been conducting observations toward the comet 103P to determine taxonomy and cosmogonic quantities, such as the ortho:para ratio and isotope ratios. Here we report detections of HCN, H2CO, CS, and OH and upper limits on HNC and DCN toward comet 103P, using the Arizona Radio Observatory Kitt Peak 12m (12m) and submillimeter telescopes (SMT), the James Clerk Maxwell Telescope (JCMT) and the Greenbank Telescope (GBT). From these data physical parameters such as temperature, column densities, and production rates have been determined toward comet 103P. The ortho:para ratio has been derived from H2CO. We used the JCMT data to compute the D/H ratio from DCN and HCN. Here we present our analysis and discuss the origin of volatiles in cometary material.

  14. Observation of tunable optical filtering in photosensitive composite structures containing liquid crystals.

    PubMed

    Gilardi, Giovanni; De Sio, Luciano; Beccherelli, Romeo; Asquini, Rita; d'Alessandro, Antonio; Umeton, Cesare

    2011-12-15

    We report on the investigation and characterization of an optically tunable filtering effect, observed in a waveguide grating made of alternated strips of photocurable polymer and a mixture of azo-dye-doped liquid crystal. The grating is sandwiched between two borosilicate glasses, one of which includes an ion-exchanged channel waveguide, which confines the optical signal to be filtered. Exposure to a low power visible light beam modifies the azo-dye molecular configuration, thus allowing the filtered wavelength to be tuned over a 6.6 nm range. Simulations of the filtering response are well described with our experimental findings. PMID:22179873

  15. Experimental observations of scale effects on bonded and bolted joints in composite structures

    NASA Technical Reports Server (NTRS)

    Grimes, Glenn C.

    1994-01-01

    The objective is to observe size (scale) effects in (1) fiber dominated laminates and bolted joints, (2) adhesive (matrix) dominated bonded joints with fiber dominated laminate adherends, and (3) matrix dominated laminates. Selected literature on scale effects is reviewed with comments and test data from one source that is analyzed for predicted and actual scale effects utilizing uniaxial loaded static strength, spectrum fatigue residual strength, and spectrum fatigue lifetime test results. Causes of scale effects are discussed, the results are summarized, and conclusions are made.

  16. Looking for Calcium Phosphate Composite Suitable to Study Osteoclast Endocytosis: Preliminary Observations

    PubMed Central

    Nicolin, V; Baldini, G; De Iaco, D; Bortul, R; Turco, G; Nori, SL

    2016-01-01

    One of the issues regarding in vitro study of bone resorption is the synthesis of a bone-like biomaterial forming a thin layer onto either glass or plastic. The synthesis of a bone-like material suitable for in vitro studies can be valuable both to investigate osteoclast differentiation, that in vivo proceeds within the local microenvironment of bone and to understand how its presence triggers activation of macrophages present in situ when bone is damaged (a scenario that can occur for example in case of bone fracture). Despite the intensive studies committed to recreate synthetic bone analogues, the most used substrates for in vitro studies on bone resorption are slices of bone or dentine. Therefore morphological investigations (i.e. fluorescence analysis and phase contrast) are strongly compromised due to the thickness of the bone analogue. In the present study, with the aim to guarantee a versatile (and easy to be made) substrate, that could be suitable to study cell adhesion and morphology by epifluorescence, phase contrast and TEM, we developed a biomaterial containing a calcium phosphate salt and type I collagen. This material (made specifically for in vitro studies) forms a very thin layer that allowed to merge the morphological information derived from phase-contrast and epifluorescence observation, making possible the observation of the interface between cell and matrix. Moreover the electron microscopy evaluation of the endocytosis performed on cell differentiated could be more suitable because sample does not need the process of demineralization. PMID:27326391

  17. MESSENGER observations of the composition of Mercury's ionized exosphere and plasma environment.

    PubMed

    Zurbuchen, Thomas H; Raines, Jim M; Gloeckler, George; Krimigis, Stamatios M; Slavin, James A; Koehn, Patrick L; Killen, Rosemary M; Sprague, Ann L; McNutt, Ralph L; Solomon, Sean C

    2008-07-01

    The region around Mercury is filled with ions that originate from interactions of the solar wind with Mercury's space environment and through ionization of its exosphere. The MESSENGER spacecraft's observations of Mercury's ionized exosphere during its first flyby yielded Na+, O+, and K+ abundances, consistent with expectations from observations of neutral species. There are increases in ions at a mass per charge (m/q) = 32 to 35, which we interpret to be S+ and H2S+, with (S+ + H2S+)/(Na+ + Mg+) = 0.67 +/- 0.06, and from water-group ions around m/q = 18, at an abundance of 0.20 +/- 0.03 relative to Na+ plus Mg+. The fluxes of Na+, O+, and heavier ions are largest near the planet, but these Mercury-derived ions fill the magnetosphere. Doubly ionized ions originating from Mercury imply that electrons with energies less than 1 kiloelectron volt are substantially energized in Mercury's magnetosphere. PMID:18599777

  18. The Composition and Structure of Enceladus' Plume from a Cassini UVIS Observation of a Solar Occultation

    NASA Astrophysics Data System (ADS)

    Hansen, C. J.; Shemansky, D. E.; Esposito, L. W.; Stewart, I.; Hendrix, A. R.

    2010-12-01

    The Cassini Ultraviolet Imaging Spectrograph (UVIS) observed an occultation of the sun by Enceladus’ water vapor plume on May 18, 2010. UVIS used its extreme ultraviolet (EUV) channel for this new observation, to detect absorptions in the wavelength range 55 to 110 nm. Molecular nitrogen and water vapor have absorptions in this range. The N2 b(3,0) line is at 97.2 nm, extinguishing the solar H Lyman gamma emission. Cassini’s Ion and Neutral Mass Spectrometer (INMS) detected a species with an atomic mass of 28 amu, which could be CO, C2H4 or N2 [1, 2]. Definitive UVIS detection of N2 was important to clear up this ambiguity, and this was an important goal of the observation, as the presence or lack of N2 is key to models of the geochemistry in the interior [3, 4, 5]. UVIS did not detect N2 and we set an upper limit for the column density of 3 x 10^13 cm^-2. The absorption features in the spectrum are best fit by a water vapor column density of 0.9 x 10^16 cm^-2. This column density is in family with previous UVIS measurements from stellar occultations in 2005 and 2007 at far ultraviolet wavelengths, suggesting that Enceladus’ activity has been stable for the last 5 years [6, 7]. We used fluctuations in the signal to probe the structure of the gas jets again, as was analyzed in the 2007 occultation of zeta Orionis [7]. Gas jets are correlated to the dust jets detected by Cassini’s Imaging Science Subsystem [8]. The path of the sun cut through the jets horizontally at an altitude above the limb of ~15 km at the closest point. The resolution of the solar occultation is higher than the stellar occultation, and collimation of the gas jets observed in the solar occultation is greater than estimated in 2007. The observed collimation allows us to derive a mach number of ~4 for the ratio of the vertical velocity in the jet to the thermal velocity of the plume gas. The new opportunity afforded by this solar occultation is used to further model the structure and

  19. Energy-dependent parameterization of heavy-ion absorption cross sections

    NASA Technical Reports Server (NTRS)

    Townsend, L. W.; Wilson, J. W.

    1986-01-01

    An energy-dependent parameterization of the total absorption (reaction) cross sections for heavy ion (Z equal to or greater than 2) collisions at energies above 25 MeV per nucleon is presented. The formula will be especially useful in heavy-ion transport applications.

  20. Importance of the energy-dependent geometry in the 16O+ 16O optical model potential

    NASA Astrophysics Data System (ADS)

    Pantis, G.; Ioannidis, K.; Poirier, P.

    1985-08-01

    Optical model potentials with various forms of energy-dependent geometry have been considered for the description of 16O+ 16O elastic scattering. It is shown that the variation with energy of the imaginary radius leads to a reasonable fit of the cross-section data, throughout the energy range.

  1. Radial inhomogeneities in particle composition of single, levitated aerosol particles observed by Mie resonance spectroscopy (Invited)

    NASA Astrophysics Data System (ADS)

    Krieger, U. K.; Steimer, S.; Lienhard, D.; Bastelberger, S.

    2013-12-01

    Recent observations have indicated that organic aerosol particles in the atmosphere may exist in an amorphous semi-solid or even solid (i.e. glassy) state, e.g. [1]. The influence of highly viscous and glassy states on the timescale of aerosol particle equilibration with respect to water vapor have been investigated for some model systems of atmospheric aerosol, e.g. [2,3]. In particular, it has been shown that the kinetics of the water absorption/desorption process is controlled entirely by liquid-phase diffusion of water molecules for a highly viscous aerosol particle. A liquid phase diffusion model based on numerically solving the non-linear diffusion equation predicts strong internal gradients in water concentration when condensed phase diffusion impedes the water uptake from the gas phase [2]. Here we observe and quantify the internal concentration gradients in single, levitated, micron size aerosol particles of aqueous MBTCA (3-methyl-1,2,3-Butanetricarboxylic acid) and shikimic acid using elastic Mie resonance spectroscopy. A single, aqueous particle is levitated in an electro-dynamic balance (for details see [2]), dried for several days at room temperature, cooled to the target temperature and exposed to a rapid change in relative humidity. In addition to measuring the elastically backscattered light of a 'white light ' LED source and recording the full spectrum with a spectrograph as in [2], we use a tunable diode laser (TDL) to scan high resolution TE- and TM spectra. This combination allows observing various Mie resonance mode orders simultaneously. Since we perform the experiment at low temperatures and low humidities the changes in the Mie-spectra due to water uptake are sufficiently slow to resolve the kinetics. Experimental Mie resonance spectra are inverted to concentration profiles of water within the particle by applying the numerical diffusion model [2] in conjunction with Mie calculations of multilayered spheres [4]. Potential implications for

  2. Inhomogeneities in particle composition of single, levitated aerosol particles observed by Mie resonance spectroscopy

    NASA Astrophysics Data System (ADS)

    Krieger, Ulrich; Lienhard, Daniel; Bastelberger, Sandra; Steimer, Sarah

    2014-05-01

    Recent observations have indicated that organic aerosol particles in the atmosphere may exist in an amorphous semi-solid or even solid (i.e. glassy) state, e.g. [1]. The influence of highly viscous and glassy states on the timescale of aerosol particle equilibration with respect to water vapor have been investigated for some model systems of atmospheric aerosol, e.g. [2,3]. In particular, it has been shown that the kinetics of the water absorption/desorption process is controlled entirely by liquid-phase diffusion of water molecules for a highly viscous aerosol particle. A liquid phase diffusion model based on numerically solving the non-linear diffusion equation predicts strong internal gradients in water concentration when condensed phase diffusion impedes the water uptake from the gas phase [2]. Here we observe and quantify the internal concentration gradients in single, levitated, micron size aerosol particles of aqueous shikimic acid using elastic Mie resonance spectroscopy. A single, aqueous particle is levitated in an electro-dynamic balance (for details see [2]), dried for several days at room temperature, cooled to the target temperature and exposed to a rapid change in relative humidity. In addition to measuring the elastically backscattered light of a "white light" LED source and recording the full spectrum with a spectrograph as in [2], we use a tunable diode laser (TDL) to scan high resolution TE- and TM spectra. This combination allows observing various Mie resonance mode orders simultaneously. Since we perform the experiment at low temperatures and low humidities the changes in the Mie-spectra due to water uptake are sufficiently slow to resolve the kinetics. Experimental Mie resonance spectra are inverted to concentration profiles of water within the particle by applying the numerical diffusion model [2] in conjunction with Mie calculations of multilayered spheres [4]. [1] A. Virtanen et al. (2010): An amorphous solid state of biogenic secondary

  3. Composites

    NASA Astrophysics Data System (ADS)

    Chmielewski, M.; Nosewicz, S.; Pietrzak, K.; Rojek, J.; Strojny-Nędza, A.; Mackiewicz, S.; Dutkiewicz, J.

    2014-11-01

    It is commonly known that the properties of sintered materials are strongly related to technological conditions of the densification process. This paper shows the sintering behavior of a NiAl-Al2O3 composite, and its individual components sintered separately. Each kind of material was processed via the powder metallurgy route (hot pressing). The progress of sintering at different stages of the process was tested. Changes in the microstructure were examined using scanning and transmission electron microscopy. Metal-ceramics interface was clean and no additional phases were detected. Correlation between the microstructure, density, and mechanical properties of the sintered materials was analyzed. The values of elastic constants of NiAl/Al2O3 were close to intermetallic ones due to the volume content of the NiAl phase particularly at low densities, where small alumina particles had no impact on the composite's stiffness. The influence of the external pressure of 30 MPa seemed crucial for obtaining satisfactory stiffness for three kinds of the studied materials which were characterized by a high dense microstructure with a low number of isolated spherical pores.

  4. Building oceanographic and atmospheric observation networks by composition: unmanned vehicles, communication networks, and planning and execution control frameworks

    NASA Astrophysics Data System (ADS)

    Sousa, J. T.; Pinto, J.; Martins, R.; Costa, M.; Ferreira, F.; Gomes, R.

    2014-12-01

    The problem of developing mobile oceanographic and atmospheric observation networks (MOAO) with coordinated air and ocean vehicles is discussed in the framework of the communications and control software tool chain developed at Underwater Systems and Technologies Laboratory (LSTS) from Porto University. This is done with reference to field experiments to illustrate key capabilities and to assess future MOAO operations. First, the motivation for building MOAO by "composition" of air and ocean vehicles, communication networks, and planning and execution control frameworks is discussed - in networked vehicle systems information and commands are exchanged among multiple vehicles and operators, and the roles, relative positions, and dependencies of these vehicles and operators change during operations. Second, the planning and execution control framework developed at LSTS for multi-vehicle systems is discussed with reference to key concepts such as autonomy, mixed-initiative interactions, and layered organization. Third, the LSTS tool software tool chain is presented to show how to develop MOAO by composition. The tool chain comprises the Neptus command and control framework for mixed initiative interactions, the underlying IMC messaging protocol, and the DUNE on-board software. Fourth, selected LSTS operational deployments illustrate MOAO capability building. In 2012 we demonstrated the use of UAS to "ferry" data from UUVs located beyond line of sight (BLOS). In 2013 we demonstrated coordinated observations of coastal fronts with small UAS and UUVs, "bent" BLOS through the use of UAS as communication relays, and UAS tracking of juvenile hammer-head sharks. In 2014 we demonstrated UUV adaptive sampling with the closed loop controller of the UUV residing on a UAS; this was done with the help of a Wave Glider ASV with a communications gateway. The results from these experiments provide a background for assessing potential future UAS operations in a compositional MOAO.

  5. Direct observation of interface and nanoscale compositional modulation in ternary III-As heterostructure nanowires

    SciTech Connect

    Venkatesan, Sriram; Scheu, Christina; Madsen, Morten H.; Krogstrup, Peter; Johnson, Erik; Schmid, Herbert

    2013-08-05

    Straight, axial InAs nanowire with multiple segments of Ga{sub x}In{sub 1−x}As was grown. High resolution X-ray energy-dispersive spectroscopy (EDS) mapping reveals the distribution of group III atoms at the axial interfaces and at the sidewalls. Significant Ga enrichment, accompanied by a structural change is observed at the Ga{sub x}In{sub 1−x}As/InAs interfaces and a higher Ga concentration for the early grown Ga{sub x}In{sub 1−x}As segments. The elemental map and EDS line profile infer Ga enrichment at the facet junctions between the sidewalls. The relative chemical potentials of ternary alloys and the thermodynamic driving force for liquid to solid transition explains the growth mechanisms behind the enrichment.

  6. The OH Venus nightglow spectrum: Intensity and vibrational composition from VIRTIS—Venus Express observations

    NASA Astrophysics Data System (ADS)

    Soret, Lauriane; Gérard, Jean-Claude; Piccioni, Giuseppe; Drossart, Pierre

    2012-12-01

    Limb spectra of the OH nightglow emission corresponding to the Δv=1 and Δv=2 sequences have been collected with the VIRTIS infrared imaging spectrograph on board Venus Express between April 2006 and October 2008. A detailed statistical analysis shows that the peak intensity and altitude of the two vibrational sequences are significantly correlated, with a mean intensity ratio of the two sequences of 0.38±0.37. The altitude of the maximum of the Δv=2 emission is located ∼1 km lower than Δv=1. A spectral analysis shows that the Δv=1 sequence is composed at 44.6% by the (1-0) band, 9.3% by the (3-2) band and 7.1% by the (4-3) band. The Δv=2 emission is best fitted if solely including the (2-0) band. A non-LTE model of OH vibrational population by the O3+H reaction including radiative and collisional relaxation has been used to compare the expected spectral distribution, the altitude of the emission peak and the emission rate under different assumptions on the quenching processes to those observed with VIRTIS. The adopted carbon dioxide, atomic oxygen and ozone densities are based on recent Venus Express remote sensing measurements. We find that the “Sudden Death” quenching scheme by CO2 produces inadequate spectral distribution between the various bands and insufficient airglow brightness. Instead, the observed spectral distribution and the total emission intensity are reasonably well reproduced with the Single Quantum jump model, an O density profile peaking at 103.5 km with a maximum value of 1.9×1011 cm-3, a O3 density profile peaking at 5.8×106 cm-3 at 96.5 km and a H density profile close to 108 cm-3 between 90 and 120 km, in agreement with several photochemical models.

  7. Detection of special nuclear material by observation of delayed neutrons with a novel fast neutron composite detector

    NASA Astrophysics Data System (ADS)

    Mayer, Michael; Nattress, Jason; Barhoumi Meddeb, Amira; Foster, Albert; Trivelpiece, Cory; Rose, Paul; Erickson, Anna; Ounaies, Zoubeida; Jovanovic, Igor

    2015-10-01

    Detection of shielded special nuclear material is crucial to countering nuclear terrorism and proliferation, but its detection is challenging. By observing the emission of delayed neutrons, which is a unique signature of nuclear fission, the presence of nuclear material can be inferred. We report on the observation of delayed neutrons from natural uranium by using monoenergetic photons and neutrons to induce fission. An interrogating beam of 4.4 MeV and 15.1 MeV gamma-rays and neutrons was produced using the 11B(d,n-γ)12C reaction and used to probe different targets. Neutron detectors with complementary Cherenkov detectors then discriminate material undergoing fission. A Li-doped glass-polymer composite neutron detector was used, which displays excellent n/ γ discrimination even at low energies, to observe delayed neutrons from uranium fission. Delayed neutrons have relatively low energies (~0.5 MeV) compared to prompt neutrons, which makes them difficult to detect using recoil-based detectors. Neutrons were counted and timed after the beam was turned off to observe the characteristic decaying time profile of delayed neutrons. The expected decay of neutron emission rate is in agreement with the common parametrization into six delayed neutron groups.

  8. Comet C/2012 S1 (ISON) coma composition at ~4 au from HST observations

    NASA Astrophysics Data System (ADS)

    Zubko, Evgenij; Videen, Gorden; Hines, Dean C.; Shkuratov, Yuriy; Kaydash, Vadym; Muinonen, Karri; Knight, Matthew M.; Sitko, Michael L.; Lisse, Carey M.; Mutchler, Max; Wooden, Diane H.; Li, Jian-Yang; Kobayashi, Hiroshi

    2015-12-01

    We analyze the first color and polarization images of Comet ISON (C/2012 S1) taken during two measurement campaigns of the Hubble Space Telescope (HST) on UTC 2013 April 10 and May 8, when the phase angles of Comet ISON were α≈13.7° and 12.2°, respectively. We model the particles in the coma using highly irregular agglomerated debris particles. Even though the observations were made over a small range of phase angle, the data still place significant constraints on the material properties of the cometary coma. The different photo-polarimetric responses are indicative of spatial chemical heterogeneity of coma in Comet ISON. For instance, at small projected distances to the nucleus (<500 km), our modeling suggests the cometary particles are composed predominantly of small, highly absorbing particles, such as amorphous carbon and/or organics material heavily irradiated with UV radiation; whereas, at longer projected distances (>1000 km), the refractive index of the particles is consistent with organic matter slightly processed with UV radiation, tholins, Mg-Fe silicates, and/or Mg-rich silicates contaminated with ~10% (by volume) amorphous carbon. The modeling suggests low relative abundances of particles with low material absorption in the visible, i.e., Im(m)≤0.02. Such particles were detected unambiguously in other comets in the vicinity of nucleus through very strong negative polarization near backscattering (P≈-6%) and very low positive polarization (P≈3-5%) at side scattering. These materials were previously attributed to Mg-rich silicates forming a refractory surface layer on the surface of cometary nuclei (Zubko et al., 2012). The absence of such particles in Comet ISON could imply an absence of such a layer on its nucleus.

  9. Composite characteristics of Nor'westers based on observations and simulations

    NASA Astrophysics Data System (ADS)

    Das, Someshwar; Sarkar, Abhijit; Das, Mohan K.; Rahman, Md. Mizanur; Islam, Md. Nazrul

    2015-05-01

    The Nor'westers (severe thunderstorms) that form over northeast India and adjoining Bangladesh region during the pre-monsoon season of 2008 are studied employing observations from ground based radar, Tropical Rainfall Measuring Mission (TRMM) and synoptic stations. Subsequently, an attempt is made to simulate the storms using Weather Research and Forecasting (WRF) model at 9 km horizontal resolution, and 28 vertical levels. Analyses of Radar data for 15 cases out of 108 during the study period showed that the Nor'westers typically propagate in the form of squall lines (parallel bow shaped bands) having horizontal length of about 200 km, reaching more than 400 km on some occasions. They propagate at typical speeds of about 50 km h- 1 from northwest to southeast directions. The model underestimated the strength of the squall lines in terms of wind speed. The simulated results showed the presence of strong vertical wind shear and an advection of warm moist southerly wind from the Bay of Bengal during the formation of Nor'westers. Low level positive vorticity in combination with moist southerly wind from the Bay of Bengal and strong surface heating resulted in the formations of the Nor'westers in all the cases. Cloud tops reached as high as 18-20 km in some of the cases of the severe storms. The altitude of core of maximum precipitation was located between 3-5 km. Average cloud hydrometeor content of the Nor'westers was estimated to be about 3.5 g m- 3.

  10. Saturn's stratospheric temperature and composition in 2015 from Cassini/CIRS limb observations

    NASA Astrophysics Data System (ADS)

    Guerlet, Sandrine; Fouchet, Thierry; Hesman, Brigette; Bjoraker, Gordon; Spiga, Aymeric; Sylvestre, Melody

    2015-11-01

    As Cassini's solstice mission goes on, our understanding of Saturn's atmospheric seasonal evolution continues to build up. Infrared spectra acquired by Cassini/CIRS in limb viewing geometry in 2015 (end of spring in the northern hemisphere) are analysed to retrieve vertical profiles of the stratospheric temperature and hydrocarbon abundances at several latitudes spanning tropical, mid and high latitudes.These new measurements reveal how the equatorial oscillation continues to propagate downward with time, and help better characterize its period. At 40N, the previously observed temperature anomaly and enrichment in hydrocarbons associated with the 2011 storm have since disappeared. Compared to previous measurements acquired between 2005 and 2012 (Guerlet et al., Icarus, 2009; Sylvestre et al., Icarus, 2015), these new limb measurements also allow the study of the warming and cooling trends at different pressure levels associated with the change of seasons. These trends will be compared to predictions from a radiative climate model (Guerlet et al., Icarus, 2014).We also report the detection of benzene and aerosols at 77N, which confirms that these compounds are enhanced in auroral regions compared to low and mid latitudes, as already derived from a previous measurement at 80S in 2007 (Guerlet et al., A&A, 2015). The aerosol optical depth is found twice lower at 77N in 2015 (end of spring in N. hemisphere) than that derived at 80S in 2007 (end of summer in S. hemisphere). However, whether this north/south difference stems from a permanent asymmetry or from a temporal variation of the aerosol optical depth cannot be assessed from these two measurements alone. We will discuss implications for the role of aerosols in the radiative forcing of the polar regions.

  11. ROSAT PSPC and HRI observations of the composite starburst/Seyfert 2 galaxy NGC 1672

    NASA Technical Reports Server (NTRS)

    Brandt, W. N.; Halpern, Jules P.; Iwasawa, K.

    1995-01-01

    The nearby barred spiral galaxy NGC 1672 has been observed with the Position Sensitive Proportional Counter (PSPC) and High Resolution Imager (HRI) instruments on board the ROSAT X-ray satellite. NGC 1672 is thought to have an obscured Seyfert nucleus, and it has strong starburst activity as well. Three bright X-ray sources with luminosities 1-2 x 10(exp 40) erg/s are clearly identified with NGC 1672. The strongest lies at the nucleus, and the other two lie at the ends of NGC 1672's prominent bar, locations that are also bright in H alpha and near-infrared images. The nuclear source is resolved by the HRI on about the scale of the recently identified nuclear ring, and one of the sources at the ends of the bar is also probably resolved. The X-ray spectrum of the nuclear source is quite soft, having a Raymond-Smith plasma temperature of approximately equals 0.7 keV and little evidence for intrinsic absorption. The ROSAT band X-ray flux of the nuclear source appears to be dominated not by X-ray binary emission but rather by diffuse gas emission. The absorption and emission properties of the sources, as well as their spatial extents, lead us to models of superbubbles driven by supernovae. However, the large density and emission measure of the nuclear X-ray source stretch the limits that can be comfortably accommodated by these models. We do not detect direct emission from the putative Seyfert nucleus, although an alternative model for the nuclear source is thermal emission from gas that is photoionized by a hidden Seyfert nucleus. The spectra of the other two X-ray sources are harder than that of the nuclear source, and have similar difficulties with regard to superbubble models.

  12. Can we differentiate alpine groundwater storages regarding volume and residence time by recession observations, ion composition and tracer balance?

    NASA Astrophysics Data System (ADS)

    Floriancic, Marius; Smoorenburg, Maarten; Margreth, Michael; Naef, Felix

    2015-04-01

    Research on how catchments store and release water is essential to improve flood and low flow prediction in (un)gauged watersheds. Despite their importance for catchment scale assessments on runoff generation, knowledge on storage properties and residence times is still limited. Here we present some approaches to separate different storage types regarding their residence time and a quantification of the volumes of these storages based on a dataset of winter recession observation in the alpine Poschiavino headwater area. This spatially highly resolved dataset of discharge, electric conductivity and ion composition from a watershed with strongly contrasting storage properties, allowed separating three main contributing sources: continuous discharge from bedrock cracks, strongly delayed discharge from thick sediment deposits and fractured rock and rapid discharge from shallow layers. The gradients of the recession curves, the variation of electric conductivity in the river network and calculated tracer balance were used to separate contribution from different sources. Additionally contribution from sedimentary rocks and crystalline layers could be separated based on the variation of ion composition in the water samples. We derived recession curves for a period of four months for the separated storages in different parts of the catchment allowing estimation of the contributed volumes in this time period. Finally the spatial distribution of the storage types could be mapped throughout the catchment based on information like geo(morpho)logical maps, aerial photographs, DEM and field observations. We found significant variation comparing the discharged volume and specific discharge throughout the winter season in the different subcatchments. Constant discharge from bedrock cracks is similar in all catchment parts. Storage in the shallow deposits depleted quickly. High winter discharge could be attributed to thick quaternary deposits contributing during the whole

  13. Periodontal repair in dogs: histologic observations of guided tissue regeneration with a prostaglandin E1 analog/methacrylate composite.

    PubMed

    Trombelli, L; Lee, M B; Promsudthi, A; Guglielmoni, P G; Wikesjö, U M

    1999-06-01

    This report describes observations of healing following guided tissue regeneration (GTR) including surgical implantation of the prostaglandin E1 analog misoprostol with calcium-layered methacrylate particles. Critical size, supra-alveolar periodontal defects were surgically created around the 3rd and 4th mandibular premolar teeth in 4 beagle dogs. Wound management included soaking with a 24 microg/ml misoprostol solution and implantation of the misoprostol/methacrylate composite. One jaw quadrant per animal was prepared for GTR using expanded polytetrafluoroethylene membranes. The gingival flaps were coronally advanced and sutured to submerge the teeth. The tissues covering the surgical sites daily received topical misoprostol in an oral adhesive over the 4-week healing interval. Upon euthanasia, tissue blocks were prepared for histometric analysis of regeneration of alveolar bone and cementum, root resorption and ankylosis. The defect area underneath the membrane and the density of methacrylate particles were recorded for the GTR defects. The methacrylate particles appeared encapsulated in a dense connective tissue without signs of an inflammatory reaction, some in contact to newly formed bone. Alveolar bone regeneration height averaged (+/-SD) 1.2+/-1.0 and 1.0+/-0.6 mm for GTR and non-GTR defects, respectively. Corresponding values for bone regeneration area were 1.3+/-1.0 and 0.7+/-0.5 mm2. Cementum regeneration was confined to the apical aspect of the defects. Small areas of root resorption and ankylosis were observed for all teeth. Bone regeneration area correlated positively to the defect area and negatively to the density of methacrylate particles in the GTR defects. The histologic observations suggest that the methacrylate composite has marginal potential to promote bone and cementum regeneration under provisions for GTR. PMID:10382578

  14. Mercury's Neutral and Ionized Exosphere Observed with the Mercury Atmospheric and Surface Composition Spectrometer During the Three MESSENGER Flybys

    NASA Astrophysics Data System (ADS)

    Vervack, Ronald J.; Killen, R. M.; McClintock, W. E.; Sprague, A. L.; Burger, M. H.; Benna, M.; Mouawad, N.; Bradley, E. T.; Anderson, B. J.; Izenberg, N. R.; Kochte, M. C.; Lankton, M. R.; Solomon, S. C.

    2010-10-01

    The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) on the MESSENGER spacecraft observed Mercury's exosphere during each of the probe's three Mercury flybys (M1 on 14 January 2008, M2 on 6 October 2008, and M3 on 29 September 2009). Two previously observed species, Na and Ca, were seen in unprecedented spatial resolution, and two species - Mg and Ca+ - were discovered in the exosphere by MASCS. A dawn/dusk asymmetry in the Ca exosphere with a dawnside enhancement was found to be a persistent feature that was not previously known to exist. Surprisingly, a corresponding feature was not seen in Mg or the more volatile species Na. A dawn/dusk asymmetry in Na cannot necessarily be ruled out because MASCS did not observe the dayside. Most surprising was the observation of a region of intense concentration of Ca+ about 2-3 planetary radii anti-sunward from the planet's center. This measurement provides evidence for tailward magnetospheric convection of photoions produced inside the magnetosphere. Observations of neutral sodium, calcium, and magnesium above the planet's north and south poles revealed altitude distributions that are distinct for each species. Strong emission was seen above the poles in each of these species, but the altitude distribution was most unusual for Mg and is inconsistent with an exponentially decreasing density with altitude. A two-component exosphere was clearly measured for Na, indicating that a combination of processes is at work in producing and maintaining the exosphere. Whereas the Na distribution is consistent with ground-based observations, the differences in spatial distributions for the chemically similar elements, Ca and Mg, are unexpected and remain unexplained.

  15. Beam-Energy Dependence of Charge Separation along the Magnetic Field in Au +Au Collisions at RHIC

    NASA Astrophysics Data System (ADS)

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Alford, J.; Anson, C. D.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Averichev, G. S.; Banerjee, A.; Beavis, D. R.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bichsel, H.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Borowski, W.; Bouchet, J.; Brandin, A. V.; Brovko, S. G.; Bültmann, S.; Bunzarov, I.; Burton, T. P.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Cebra, D.; Cendejas, R.; Cervantes, M. C.; Chaloupka, P.; Chang, Z.; Chattopadhyay, S.; Chen, H. F.; Chen, J. H.; Chen, L.; Cheng, J.; Cherney, M.; Chikanian, A.; Christie, W.; Chwastowski, J.; Codrington, M. J. M.; Contin, G.; Cramer, J. G.; Crawford, H. J.; Cui, X.; Das, S.; Davila Leyva, A.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; Derradi de Souza, R.; Dhamija, S.; di Ruzza, B.; Didenko, L.; Dilks, C.; Ding, F.; Djawotho, P.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Engelage, J.; Engle, K. S.; Eppley, G.; Eun, L.; Evdokimov, O.; Eyser, O.; Fatemi, R.; Fazio, S.; Fedorisin, J.; Filip, P.; Finch, E.; Fisyak, Y.; Flores, C. E.; Gagliardi, C. A.; Gangadharan, D. R.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Gliske, S.; Greiner, L.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, A.; Gupta, S.; Guryn, W.; Haag, B.; Hamed, A.; Han, L.-X.; Haque, R.; Harris, J. W.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Hofman, D. J.; Horvat, S.; Huang, B.; Huang, H. Z.; Huang, X.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jang, H.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Kesich, A.; Khan, Z. H.; Kikola, D. P.; Kisel, I.; Kisiel, A.; Koetke, D. D.; Kollegger, T.; Konzer, J.; Koralt, I.; Kotchenda, L.; Kraishan, A. F.; Kravtsov, P.; Krueger, K.; Kulakov, I.; Kumar, L.; Kycia, R. A.; Lamont, M. A. C.; Landgraf, J. M.; Landry, K. D.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; LeVine, M. J.; Li, C.; Li, W.; Li, X.; Li, X.; Li, Y.; Li, Z. M.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, X.; Ma, G. L.; Ma, Y. G.; Madagodagettige Don, D. M. M. D.; Mahapatra, D. P.; Majka, R.; Margetis, S.; Markert, C.; Masui, H.; Matis, H. S.; McDonald, D.; McShane, T. S.; Minaev, N. G.; Mioduszewski, S.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nelson, J. M.; Nigmatkulov, G.; Nogach, L. V.; Noh, S. Y.; Novak, J.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Ohlson, A.; Okorokov, V.; Oldag, E. W.; Olvitt, D. L.; Pachr, M.; Page, B. S.; Pal, S. K.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlak, T.; Pawlik, B.; Pei, H.; Perkins, C.; Peryt, W.; Pile, P.; Planinic, M.; Pluta, J.; Poljak, N.; Porter, J.; Poskanzer, A. M.; Pruthi, N. K.; Przybycien, M.; Pujahari, P. R.; Putschke, J.; Qiu, H.; Quintero, A.; Ramachandran, S.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Riley, C. K.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Ross, J. F.; Roy, A.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandweiss, J.; Sangaline, E.; Sarkar, A.; Schambach, J.; Scharenberg, R. P.; Schmah, A. M.; Schmidke, W. B.; Schmitz, N.; Seger, J.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shanmuganathan, P. V.; Shao, M.; Sharma, B.; Shen, W. Q.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Singaraju, R. N.; Skoby, M. J.; Smirnov, D.; Smirnov, N.; Solanki, D.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stevens, J. R.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Sumbera, M.; Sun, X.; Sun, X. M.; Sun, Y.; Sun, Z.; Surrow, B.; Svirida, D. N.; Symons, T. J. M.; Szelezniak, M. A.; Takahashi, J.; Tang, A. H.; Tang, Z.; Tarnowsky, T.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Trzeciak, B. A.; Tsai, O. D.; Turnau, J.; Ullrich, T.; Underwood, D. G.; Van Buren, G.; van Nieuwenhuizen, G.; Vandenbroucke, M.; Vanfossen, J. A.; Varma, R.; Vasconcelos, G. M. S.; Vasiliev, A. N.; Vertesi, R.; Videbæk, F.; Viyogi, Y. P.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wada, M.; Wang, F.; Wang, G.; Wang, H.; Wang, J. S.; Wang, X. L.; Wang, Y.; Wang, Y.; Webb, G.; Webb, J. C.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y. F.; Xiao, Z.; Xie, W.; Xin, K.; Xu, H.; Xu, J.; Xu, N.; Xu, Q. H.; Xu, Y.; Xu, Z.; Yan, W.; Yang, C.; Yang, Y.; Yang, Y.; Ye, Z.; Yepes, P.; Yi, L.; Yip, K.; Yoo, I.-K.; Yu, N.; Zawisza, Y.; Zbroszczyk, H.; Zha, W.; Zhang, J. B.; Zhang, J. L.; Zhang, S.; Zhang, X. P.; Zhang, Y.; Zhang, Z. P.; Zhao, F.; Zhao, J.; Zhong, C.; Zhu, X.; Zhu, Y. H.; Zoulkarneeva, Y.; Zyzak, M.; STAR Collaboration

    2014-08-01

    Local parity-odd domains are theorized to form inside a quark-gluon plasma which has been produced in high-energy heavy-ion collisions. The local parity-odd domains manifest themselves as charge separation along the magnetic field axis via the chiral magnetic effect. The experimental observation of charge separation has previously been reported for heavy-ion collisions at the top RHIC energies. In this Letter, we present the results of the beam-energy dependence of the charge correlations in Au +Au collisions at midrapidity for center-of-mass energies of 7.7, 11.5, 19.6, 27, 39, and 62.4 GeV from the STAR experiment. After background subtraction, the signal gradually reduces with decreased beam energy and tends to vanish by 7.7 GeV. This implies the dominance of hadronic interactions over partonic ones at lower collision energies.

  16. Momentum and energy dependence of the anomalous high-energy dispersion in the electronic structure of high temperature superconductors.

    PubMed

    Inosov, D S; Fink, J; Kordyuk, A A; Borisenko, S V; Zabolotnyy, V B; Schuster, R; Knupfer, M; Büchner, B; Follath, R; Dürr, H A; Eberhardt, W; Hinkov, V; Keimer, B; Berger, H

    2007-12-01

    Using high-resolution angle-resolved photoemission spectroscopy we have studied the momentum and photon energy dependence of the anomalous high-energy dispersion, termed waterfalls, between the Fermi level and 1 eV binding energy in several high-T_{c} superconductors. We observe strong changes of the dispersion between different Brillouin zones and a strong dependence on the photon energy around 75 eV, which we associate with the resonant photoemission at the Cu3p-->3d_{x;{2}-y;{2}} edge. We conclude that the high-energy "waterfall" dispersion results from a strong suppression of the photoemission intensity at the center of the Brillouin zone due to matrix element effects and is, therefore, not an intrinsic feature of the spectral function. This indicates that the new high-energy scale in the electronic structure of cuprates derived from the waterfall-like dispersion may be incorrect. PMID:18233401

  17. Excitation laser energy dependence of surface-enhanced fluorescence showing plasmon-induced ultrafast electronic dynamics in dye molecules

    NASA Astrophysics Data System (ADS)

    Itoh, Tamitake; Yamamoto, Yuko S.; Tamaru, Hiroharu; Biju, Vasudevanpillai; Murase, Norio; Ozaki, Yukihiro

    2013-06-01

    We find unique properties accompanying surface-enhanced fluorescence (SEF) from dye molecules adsorbed on Ag nanoparticle aggregates, which generate surface-enhanced Raman scattering. The properties are observed in excitation laser energy dependence of SEF after excluding plasmonic spectral modulation in SEF. The unique properties are large blue shifts of fluorescence spectra, deviation of ratios between anti-Stokes SEF intensity and Stokes from those of normal fluorescence, super-broadening of Stokes spectra, and returning to original fluorescence by lower energy excitation. We elucidate that these properties are induced by electromagnetic enhancement of radiative decay rates exceeding the vibrational relaxation rates within an electronic excited state, which suggests that molecular electronic dynamics in strong plasmonic fields can be largely deviated from that in free space.

  18. Momentum and Energy Dependence of the Anomalous High-Energy Dispersion in the Electronic Structure of High Temperature Superconductors

    NASA Astrophysics Data System (ADS)

    Inosov, D. S.; Fink, J.; Kordyuk, A. A.; Borisenko, S. V.; Zabolotnyy, V. B.; Schuster, R.; Knupfer, M.; Büchner, B.; Follath, R.; Dürr, H. A.; Eberhardt, W.; Hinkov, V.; Keimer, B.; Berger, H.

    2007-12-01

    Using high-resolution angle-resolved photoemission spectroscopy we have studied the momentum and photon energy dependence of the anomalous high-energy dispersion, termed waterfalls, between the Fermi level and 1 eV binding energy in several high-Tc superconductors. We observe strong changes of the dispersion between different Brillouin zones and a strong dependence on the photon energy around 75 eV, which we associate with the resonant photoemission at the Cu3p→3dx2-y2 edge. We conclude that the high-energy “waterfall” dispersion results from a strong suppression of the photoemission intensity at the center of the Brillouin zone due to matrix element effects and is, therefore, not an intrinsic feature of the spectral function. This indicates that the new high-energy scale in the electronic structure of cuprates derived from the waterfall-like dispersion may be incorrect.

  19. Beam-energy dependence of charge separation along the magnetic field in Au+Au collisions at RHIC.

    PubMed

    Adamczyk, L; Adkins, J K; Agakishiev, G; Aggarwal, M M; Ahammed, Z; Alekseev, I; Alford, J; Anson, C D; Aparin, A; Arkhipkin, D; Aschenauer, E C; Averichev, G S; Banerjee, A; Beavis, D R; Bellwied, R; Bhasin, A; Bhati, A K; Bhattarai, P; Bichsel, H; Bielcik, J; Bielcikova, J; Bland, L C; Bordyuzhin, I G; Borowski, W; Bouchet, J; Brandin, A V; Brovko, S G; Bültmann, S; Bunzarov, I; Burton, T P; Butterworth, J; Caines, H; Calderón de la Barca Sánchez, M; Cebra, D; Cendejas, R; Cervantes, M C; Chaloupka, P; Chang, Z; Chattopadhyay, S; Chen, H F; Chen, J H; Chen, L; Cheng, J; Cherney, M; Chikanian, A; Christie, W; Chwastowski, J; Codrington, M J M; Contin, G; Cramer, J G; Crawford, H J; Cui, X; Das, S; Davila Leyva, A; De Silva, L C; Debbe, R R; Dedovich, T G; Deng, J; Derevschikov, A A; Derradi de Souza, R; Dhamija, S; di Ruzza, B; Didenko, L; Dilks, C; Ding, F; Djawotho, P; Dong, X; Drachenberg, J L; Draper, J E; Du, C M; Dunkelberger, L E; Dunlop, J C; Efimov, L G; Engelage, J; Engle, K S; Eppley, G; Eun, L; Evdokimov, O; Eyser, O; Fatemi, R; Fazio, S; Fedorisin, J; Filip, P; Finch, E; Fisyak, Y; Flores, C E; Gagliardi, C A; Gangadharan, D R; Garand, D; Geurts, F; Gibson, A; Girard, M; Gliske, S; Greiner, L; Grosnick, D; Gunarathne, D S; Guo, Y; Gupta, A; Gupta, S; Guryn, W; Haag, B; Hamed, A; Han, L-X; Haque, R; Harris, J W; Heppelmann, S; Hirsch, A; Hoffmann, G W; Hofman, D J; Horvat, S; Huang, B; Huang, H Z; Huang, X; Huck, P; Humanic, T J; Igo, G; Jacobs, W W; Jang, H; Judd, E G; Kabana, S; Kalinkin, D; Kang, K; Kauder, K; Ke, H W; Keane, D; Kechechyan, A; Kesich, A; Khan, Z H; Kikola, D P; Kisel, I; Kisiel, A; Koetke, D D; Kollegger, T; Konzer, J; Koralt, I; Kotchenda, L; Kraishan, A F; Kravtsov, P; Krueger, K; Kulakov, I; Kumar, L; Kycia, R A; Lamont, M A C; Landgraf, J M; Landry, K D; Lauret, J; Lebedev, A; Lednicky, R; Lee, J H; LeVine, M J; Li, C; Li, W; Li, X; Li, X; Li, Y; Li, Z M; Lisa, M A; Liu, F; Ljubicic, T; Llope, W J; Lomnitz, M; Longacre, R S; Luo, X; Ma, G L; Ma, Y G; Madagodagettige Don, D M M D; Mahapatra, D P; Majka, R; Margetis, S; Markert, C; Masui, H; Matis, H S; McDonald, D; McShane, T S; Minaev, N G; Mioduszewski, S; Mohanty, B; Mondal, M M; Morozov, D A; Mustafa, M K; Nandi, B K; Nasim, Md; Nayak, T K; Nelson, J M; Nigmatkulov, G; Nogach, L V; Noh, S Y; Novak, J; Nurushev, S B; Odyniec, G; Ogawa, A; Oh, K; Ohlson, A; Okorokov, V; Oldag, E W; Olvitt, D L; Pachr, M; Page, B S; Pal, S K; Pan, Y X; Pandit, Y; Panebratsev, Y; Pawlak, T; Pawlik, B; Pei, H; Perkins, C; Peryt, W; Pile, P; Planinic, M; Pluta, J; Poljak, N; Porter, J; Poskanzer, A M; Pruthi, N K; Przybycien, M; Pujahari, P R; Putschke, J; Qiu, H; Quintero, A; Ramachandran, S; Raniwala, R; Raniwala, S; Ray, R L; Riley, C K; Ritter, H G; Roberts, J B; Rogachevskiy, O V; Romero, J L; Ross, J F; Roy, A; Ruan, L; Rusnak, J; Rusnakova, O; Sahoo, N R; Sahu, P K; Sakrejda, I; Salur, S; Sandweiss, J; Sangaline, E; Sarkar, A; Schambach, J; Scharenberg, R P; Schmah, A M; Schmidke, W B; Schmitz, N; Seger, J; Seyboth, P; Shah, N; Shahaliev, E; Shanmuganathan, P V; Shao, M; Sharma, B; Shen, W Q; Shi, S S; Shou, Q Y; Sichtermann, E P; Singaraju, R N; Skoby, M J; Smirnov, D; Smirnov, N; Solanki, D; Sorensen, P; Spinka, H M; Srivastava, B; Stanislaus, T D S; Stevens, J R; Stock, R; Strikhanov, M; Stringfellow, B; Sumbera, M; Sun, X; Sun, X M; Sun, Y; Sun, Z; Surrow, B; Svirida, D N; Symons, T J M; Szelezniak, M A; Takahashi, J; Tang, A H; Tang, Z; Tarnowsky, T; Thomas, J H; Timmins, A R; Tlusty, D; Tokarev, M; Trentalange, S; Tribble, R E; Tribedy, P; Trzeciak, B A; Tsai, O D; Turnau, J; Ullrich, T; Underwood, D G; Van Buren, G; van Nieuwenhuizen, G; Vandenbroucke, M; Vanfossen, J A; Varma, R; Vasconcelos, G M S; Vasiliev, A N; Vertesi, R; Videbæk, F; Viyogi, Y P; Vokal, S; Voloshin, S A; Vossen, A; Wada, M; Wang, F; Wang, G; Wang, H; Wang, J S; Wang, X L; Wang, Y; Wang, Y; Webb, G; Webb, J C; Westfall, G D; Wieman, H; Wissink, S W; Witt, R; Wu, Y F; Xiao, Z; Xie, W; Xin, K; Xu, H; Xu, J; Xu, N; Xu, Q H; Xu, Y; Xu, Z; Yan, W; Yang, C; Yang, Y; Yang, Y; Ye, Z; Yepes, P; Yi, L; Yip, K; Yoo, I-K; Yu, N; Zawisza, Y; Zbroszczyk, H; Zha, W; Zhang, J B; Zhang, J L; Zhang, S; Zhang, X P; Zhang, Y; Zhang, Z P; Zhao, F; Zhao, J; Zhong, C; Zhu, X; Zhu, Y H; Zoulkarneeva, Y; Zyzak, M

    2014-08-01

    Local parity-odd domains are theorized to form inside a quark-gluon plasma which has been produced in high-energy heavy-ion collisions. The local parity-odd domains manifest themselves as charge separation along the magnetic field axis via the chiral magnetic effect. The experimental observation of charge separation has previously been reported for heavy-ion collisions at the top RHIC energies. In this Letter, we present the results of the beam-energy dependence of the charge correlations in Au+Au collisions at midrapidity for center-of-mass energies of 7.7, 11.5, 19.6, 27, 39, and 62.4 GeV from the STAR experiment. After background subtraction, the signal gradually reduces with decreased beam energy and tends to vanish by 7.7 GeV. This implies the dominance of hadronic interactions over partonic ones at lower collision energies. PMID:25126911

  20. The oxidative activities of membrane vesicles from Bacillus caldolyticus. Energy-dependence of succinate oxidation.

    PubMed

    Dawson, A G; Chappell, J B

    1978-02-15

    1. The properties of membrane vesicles from the extreme thermophile Bacillus caldolyticus were investigated. 2. Vesicles prepared by exposure of spheroplasts to ultrasound contained cytochromes a, b and c, and at 50 degrees C they rapidly oxidized NADH and ascorbate in the presence of tetramethyl-p-phenylenediamine. Succinate and l-malate were oxidized more slowly, and dl-lactate, l-alanine and glycerol 1-phosphate were not oxidized. 3. In the absence of proton-conducting uncouplers the oxidation of NADH was accompanied by a net translocation of H(+) into the vesicles. Hydrolysis of ATP by a dicyclohexylcarbodi-imide-sensitive adenosine triphosphatase was accompanied by a similarly directed net translocation of H(+). 4. Uncouplers (carbonyl cyanide p-trifluoromethoxyphenylhydrazone or valinomycin plus NH(4) (+)) prevented net H(+) translocation but stimulated ATP hydrolysis, NADH oxidation and ascorbate oxidation. The last result suggested an energy-conserving site in the respiratory chain between cytochrome c and oxygen. 5. Under anaerobic conditions the reduction of cytochrome b by ascorbate (with tetramethyl-p-phenylenediamine) was stimulated by ATP hydrolysis, indicating an energy-conserving site between cytochrome b and cytochrome c. However, no reduction of NAD(+) supported by oxidation of succinate, malate or ascorbate occurred, neither did it with these substrates in the presence of ATP under anaerobic conditions, suggesting that there was no energy-conserving site between NADH and cytochrome b. 6. Succinate oxidation, in contrast with that of NADH and ascorbate, was strongly inhibited by uncouplers and stimulated by ATP hydrolysis. These effects were not observed when phenazine methosulphate, which transfers electrons from succinate dehydrogenase directly to oxygen, was present. It was concluded that in these vesicles the oxidation of succinate was energy-dependent and that the reoxidation of reduced succinate dehydrogenase was dependent on the outward

  1. Investigation of the energy dependence of the orbital light curve in LS 5039

    NASA Astrophysics Data System (ADS)

    Chang, Z.; Zhang, S.; Ji, L.; Chen, Y. P.; Kretschmar, P.; Kuulkers, E.; Collmar, W.; Liu, C. Z.

    2016-08-01

    LS 5039 is so far the best studied γ-ray binary system at multi-wavelength energies. A time resolved study of its spectral energy distribution (SED) shows that above 1 keV its power output is changing along its binary orbit as well as being a function of energy. To disentangle the energy dependence of the power output as a function of orbital phase, we investigated in detail the orbital light curves as derived with different telescopes at different energy bands. We analysed the data from all existing INTEGRAL/IBIS/ISGRI observations of the source and generated the most up-to-date orbital light curves at hard X-ray energies. In the γ-ray band, we carried out orbital phase-resolved analysis of Fermi-LAT data between 30 MeV and 10 GeV in 5 different energy bands. We found that, at ≲100 MeV and ≳1 TeV the peak of the γ-ray emission is near orbital phase 0.7, while between ˜100 MeV and ˜1 GeV it moves close to orbital phase 1.0 in an orbital anti-clockwise manner. This result suggests that the transition region in the SED at soft γ-rays (below a hundred MeV) is related to the orbital phase interval of 0.5-1.0 but not to the one of 0.0-0.5, when the compact object is "behind" its companion. Another interesting result is that between 3 and 20 GeV no orbital modulation is found, although Fermi-LAT significantly (˜18σ) detects LS 5039. This is consistent with the fact that at these energies, the contributions to the overall emission from the inferior conjunction phase region (INFC, orbital phase 0.45 to 0.9) and from the superior conjunction phase region (SUPC, orbital phase 0.9 to 0.45) are equal in strength. At TeV energies the power output is again dominant in the INFC region and the flux peak occurs at phase ˜0.7.

  2. Predicting the Mineral Composition of Dust Aerosols. Part 2; Model Evaluation and Identification of Key Processes with Observations

    NASA Technical Reports Server (NTRS)

    Perlwitz, J. P.; Garcia-Pando, C. Perez; Miller, R. L.

    2015-01-01

    A global compilation of nearly sixty measurement studies is used to evaluate two methods of simulating the mineral composition of dust aerosols in an Earth system model. Both methods are based upon a Mean Mineralogical Table (MMT) that relates the soil mineral fractions to a global atlas of arid soil type. The Soil Mineral Fraction (SMF) method assumes that the aerosol mineral fractions match the fractions of the soil. The MMT is based upon soil measurements after wet sieving, a process that destroys aggregates of soil particles that would have been emitted from the original, undisturbed soil. The second method approximately reconstructs the emitted aggregates. This model is referred to as the Aerosol Mineral Fraction (AMF) method because the mineral fractions of the aerosols differ from those of the wet-sieved parent soil, partly due to reaggregation. The AMF method remedies some of the deficiencies of the SMF method in comparison to observations. Only the AMF method exhibits phyllosilicate mass at silt sizes, where they are abundant according to observations. In addition, the AMF quartz fraction of silt particles is in better agreement with measured values, in contrast to the overestimated SMF fraction. Measurements at distinct clay and silt particle sizes are shown to be more useful for evaluation of the models, in contrast to the sum over all particles sizes that is susceptible to compensating errors, as illustrated by the SMF experiment. Model errors suggest that allocation of the emitted silt fraction of each mineral into the corresponding transported size categories is an important remaining source of uncertainty. Evaluation of both models and the MMT is hindered by the limited number of size-resolved measurements of mineral content that sparsely sample aerosols from the major dust sources. The importance of climate processes dependent upon aerosol mineral composition shows the need for global and routine mineral measurements.

  3. Comparison of Modeled and Observed Environmental Influences on the Stable Oxygen and Hydrogen Isotope Composition of Leaf Water in Phaseolus vulgaris L. 1

    PubMed Central

    Flanagan, Lawrence B.; Comstock, Jonathan P.; Ehleringer, James R.

    1991-01-01

    In this paper we describe how a model of stable isotope fractionation processes, originally developed by H. Craig and L. I. Gordon ([1965] in E Tongiorgi, ed, Proceedings of a Conference on Stable Isotopes in Oceanographic Studies and Paleotemperature, Spoleto, Italy, pp 9-130) for evaporation of water from the ocean, can be applied to leaf transpiration. The original model was modified to account for turbulent conditions in the leaf boundary layer. Experiments were conducted to test the factors influencing the stable isotopic composition of leaf water under controlled environment conditions. At steady state, the observed leaf water isotopic composition was enriched above that of stem water with the extent of the enrichment dependent on the leaf-air vapor pressure difference (VPD) and the isotopic composition of atmospheric water vapor (AWV). The higher the VPD, the larger was the observed heavy isotope content of leaf water. At a constant VPD, leaf water was relatively depleted in heavy isotopes when exposed to AWV with a low heavy isotope composition, and leaf water was relatively enriched in heavy isotopes when exposed to AWV with a large heavy isotope composition. However, the observed heavy isotope composition of leaf water was always less than that predicted by the model. The extent of the discrepancy between the modeled and observed leaf water isotopic composition was a strong linear function of the leaf transpiration rate. PMID:16668226

  4. SU-E-T-526: On the Linearity, Stability and Beam Energy Dependence of CdSe Quantum Dots as Scintillating Probes

    SciTech Connect

    Delage, M-E; Lecavalier, M-E; Lariviere, D; Allen, C; Beaulieu, L

    2014-06-01

    Purpose: Structure and energy transfer mechanisms confer colloidal quantum dots (cQDs) interesting properties, among them their potential as scintillators. CdSe multi-shell cQDs in powder were investigated under photons irradiation. The purpose of this work is to characterize signal to dose linearity, stability with time and to quantify the dependence of their light output with beam energy. Methods: The cQDs are placed at the extremity of a non-scintillating plastic collecting fiber, with the other extremity connected to an Apogee U2000C CCD camera. The CCD camera collects the fluorescence light from irradiated cQDs from which the delivered dose is extracted. This signal is corrected for Cerenkov contamination at MV energies using the chromatic technique. The detector was irradiated with two devices: Xstrahl 200 orthovoltage unit for 120, 180 and 220 kVp and a Varian Clinac iX for 6 and 23 MV. Results: Linear output response with varying dose is observed for all beam energies with R2 factors > 0,999. Reproducibility measurements were performed at 120 kVp: the same set-up was irradiated at different time intervals (one week and three months). The results showed only a small relative decrease of light output of 3,2 % after a combine deposited dose of approximately 95 Gy. CdSe nanocrystals response has been studied as a function of beam energy. The output increases with decreasing energy from 120 kVp to 6 MV and increase again for 23 MV. This behavior could be explained in part by the cQDs high-Z composition. Conclusion: The fluorescence light output of CdSe cQDs was found to be linear as a function of dose. The results suggest stability of the scintillation output of cQDs over time. The specific composition of cQDs is the main cause of the observed energy dependence. We will further look into particle beam dependence of the cQDs. Bourse d'excellence aux etudes graduees du CRC (Centre de Recherche sur le Cancer, Universite Laval) Bourse d'excellence aux etudes

  5. Gluon saturation and energy dependence of hadron multiplicity in pp and AA collisions at the LHC

    SciTech Connect

    Levin, Eugene; Rezaeian, Amir H.

    2011-06-01

    The recent results in {radical}(s)=2.76 TeV Pb+Pb collisions at the Large Hadron Collider (LHC) reported by the ALICE collaboration shows that the power-law energy-dependence of charged hadron multiplicity in Pb+Pb collisions is significantly different from p+p collisions. We show that this different energy-dependence can be explained by inclusion of a strong angular-ordering in the gluon-decay cascade within the color glass condensate (or gluon saturation) approach. This effect is more important in nucleus-nucleus collisions where the saturation scale is larger than 1 GeV. Our prescription gives a good description of the LHC data both in p+p and Pb+Pb collisions.

  6. Energy dependence of the probability for asymmetric fission of /sup 213/At

    SciTech Connect

    Gruzintsev, E.N.; Itkis, M.G.; Okolovich, V.N.; Rusanov, A.Y.; Smirenkin, G.N.; Tolstikov, V.N.

    1982-10-20

    The mass distribution of the fragments of the fission of /sup 213/At in the reaction /sup 209/Bi(..cap alpha.., f) has been measured for ..cap alpha.. energies in the range 34.7--50 MeV. Over the entire energy range studied, the asymmetric mode is an improbable, slightly energy-dependent mode for the /sup 213/At fission. This property of the /sup 213/At fission represents a qualitative distinction from the fission of heavy nuclei.

  7. Energy dependence of the trapping of uranium atoms by aluminum oxide surfaces

    NASA Technical Reports Server (NTRS)

    Librecht, K. G.

    1979-01-01

    The energy dependence of the trapping probability for sputtered U-235 atoms striking an oxidized aluminum collector surface at energies between 1 eV and 184 eV was measured. At the lowest energies, approximately 10% of the uranium atoms are not trapped, while above 10 eV essentially all of them stick. Trapping probabilities averaged over the sputtered energy distribution for uranium incident on gold and mica are also presented.

  8. ENERGY-DEPENDENT GAMMA-RAY BURST PULSE WIDTH DUE TO THE CURVATURE EFFECT AND INTRINSIC BAND SPECTRUM

    SciTech Connect

    Peng, Z. Y.; Ma, L.; Zhao, X. H.; Yin, Y.; Bao, Y. Y.

    2012-06-20

    Previous studies have found that the width of the gamma-ray burst (GRB) pulse is energy dependent and that it decreases as a power-law function with increasing photon energy. In this work we have investigated the relation between the energy dependence of the pulse and the so-called Band spectrum by using a sample including 51 well-separated fast rise and exponential decay long-duration GRB pulses observed by BATSE (Burst and Transient Source Experiment on the Compton Gamma Ray Observatory). We first decompose these pulses into rise and decay phases and find that the rise widths and the decay widths also behave as a power-law function with photon energy. Then we investigate statistically the relations between the three power-law indices of the rise, decay, and total width of the pulse (denoted as {delta}{sub r}, {delta}{sub d}, and {delta}{sub w}, respectively) and the three Band spectral parameters, high-energy index ({alpha}), low-energy index ({beta}), and peak energy (E{sub p} ). It is found that (1) {alpha} is strongly correlated with {delta}{sub w} and {delta}{sub d} but seems uncorrelated with {delta}{sub r}; (2) {beta} is weakly correlated with the three power-law indices, and (3) E{sub p} does not show evident correlations with the three power-law indices. We further investigate the origin of {delta}{sub d}-{alpha} and {delta}{sub w}-{alpha}. We show that the curvature effect and the intrinsic Band spectrum could naturally lead to the energy dependence of the GRB pulse width and also the {delta}{sub d}-{alpha} and {delta}{sub w}-{alpha} correlations. Our results hold so long as the shell emitting gamma rays has a curved surface and the intrinsic spectrum is a Band spectrum or broken power law. The strong {delta}{sub d}-{alpha} correlation and inapparent correlations between {delta}{sub r} and the three Band spectral parameters also suggest that the rise and decay phases of the GRB pulses have different origins.

  9. Energy Dependence of $\\bar{K}N$ Interactions and Resonance Pole of Strange Dibaryons

    SciTech Connect

    Ikeda, Y.; Kamano, H.; Sato, T.

    2010-09-01

    We study the resonance energy of the strange dibaryons using two models with the energy-independent and energy-dependent potentials for the s-wave $\\bar{K}N$ interaction, both of which are derived by certain reductions from the leading order term of the effective chiral Lagrangian. These potential models produce rather different off-shell behaviors of the two-body $\\bar{K}N$ - $\\pi\\Sigma$ amplitudes in $I=0$ channel, i.e., the model with energy-independent (energy-dependent) potential predicts one (two) resonance pole in the $\\Lambda(1405)$ region, while they describe the available data equally well. We find that the energy-independent potential model predicts one resonance pole of the strange dibaryons, whereas the energy-dependent potential model predicts two resonance poles: one is the shallow quasi-bound state of the $\\bar{K}NN$, and another is the resonance of the $\\pi Y N$ with large width. An investigation of the binding energy of the strange dibaryons will make a significant contribution to clarify resonance structure of s-wave $\\bar{K}N$ -$\\pi\\Sigma$ around the $\\Lambda(1405)$ region.

  10. On the energy dependence of the radial diffusion coefficient and spectra of inner radiation belt particles - Analytic solutions and comparison with numerical results

    NASA Technical Reports Server (NTRS)

    Westphalen, H.; Spjeldvik, W. N.

    1982-01-01

    A theoretical method by which the energy dependence of the radial diffusion coefficient may be deduced from spectral observations of the particle population at the inner edge of the earth's radiation belts is presented. This region has previously been analyzed with numerical techniques; in this report an analytical treatment that illustrates characteristic limiting cases in the L shell range where the time scale of Coulomb losses is substantially shorter than that of radial diffusion (L approximately 1-2) is given. It is demonstrated both analytically and numerically that the particle spectra there are shaped by the energy dependence of the radial diffusion coefficient regardless of the spectral shapes of the particle populations diffusing inward from the outer radiation zone, so that from observed spectra the energy dependence of the diffusion coefficient can be determined. To insure realistic simulations, inner zone data obtained from experiments on the DIAL, AZUR, and ESRO 2 spacecraft have been used as boundary conditions. Excellent agreement between analytic and numerical results is reported.

  11. PREMIER: a proposed mission to observe processes controlling atmospheric composition in the height range most important to climate

    NASA Astrophysics Data System (ADS)

    Kerridge, Brian; Orphal, Johannes; van Weele, Michiel; Murtagh, Donal; McConnell, Jack; Hegglin, Michaela; Peuch, Vincent-Henri; Reise, Martin

    2010-05-01

    The PREMIER (PRocess Exploration through Measurements of Infrared and millimetre-wave Emitted Radiation) mission is one of three candidates for ESA's 7th Earth Explorer Core Mission (due for launch in 2016) that have been approved for Phase A study. The mission proposes to make detailed measurements in the mid/upper troposphere and lower stratosphere in order to quantify processes controlling atmospheric global composition in this height range of particular importance to climate. PREMIER would consist of an infrared limb imaging spectrometer which would observe 3D fields of trace gases, alongside a millimetre-wave limb sounder which would enable observations in the presence of most cirrus clouds, and also provide complementary trace gases. In addition, co-located data from EPS-MetOp would be combined with that from PREMIER, to extend the scientific impact of PREMIER down into the lower troposphere, to explore links to surface emissions and pollution. In this presentation, simulations of its capabilities will be described together with some preliminary results from airborne precursors

  12. Gafchromic EBT3 film dosimetry in electron beams - energy dependence and improved film read-out.

    PubMed

    Sipilä, Petri; Ojala, Jarkko; Kaijaluoto, Sampsa; Jokelainen, Ilkka; Kosunen, Antti

    2016-01-01

    For megavoltage photon radiation, the fundamental dosimetry characteristics of Gafchromic EBT3 film were determined in 60Co gamma ray beam with addition of experimental and Monte Carlo (MC)-simulated energy dependence of the film for 6 MV photon beam and 6 MeV, 9 MeV, 12 MeV, and 16 MeV electron beams in water phantom. For the film read-out, two phase correction of scanner sensitivity was applied: a matrix correction for scanning area and dose-dependent correction by iterative procedure. With these corrections, the uniformity of response can be improved to be within ± 50 pixel values (PVs). To improve the read-out accuracy, a procedure with flipped film orientations was established. With the method, scanner uniformity can be improved further and dust particles, scratches and/or dirt on scan-ner glass can be detected and eliminated. Responses from red and green channels were averaged for read-out, which decreased the effect of noise present in values from separate channels. Since the signal level with the blue channel is considerably lower than with other channels, the signal variation due to different perturbation effects increases the noise level so that the blue channel is not recommended to be used for dose determination. However, the blue channel can be used for the detection of emulsion thickness variations for film quality evaluations with unexposed films. With electron beams ranging from 6 MeV to 16 MeV and at reference measurement conditions in water, the energy dependence of the EBT3 film is uniform within 0.5%, with uncertainties close to 1.6% (k = 2). Including 6 MV photon beam and the electron beams mentioned, the energy dependence is within 1.1%. No notable differences were found between the experimental and MC-simulated responses, indicating negligible change in intrinsic energy dependence of the EBT3 film for 6 MV photon beam and 6 MeV-16 MeV electron beams. Based on the dosimetric characteristics of the EBT3 film, the read-out procedure established

  13. Excitation energy-dependent nature of Raman scattering spectrum in GaInNAs/GaAs quantum well structures

    PubMed Central

    2012-01-01

    The excitation energy-dependent nature of Raman scattering spectrum, vibration, electronic or both, has been studied using different excitation sources on as-grown and annealed n- and p-type modulation-doped Ga1 − xInxNyAs1 − y/GaAs quantum well structures. The samples were grown by molecular beam technique with different N concentrations (y = 0%, 0.9%, 1.2%, 1.7%) at the same In concentration of 32%. Micro-Raman measurements have been carried out using 532 and 758 nm lines of diode lasers, and the 1064 nm line of the Nd-YAG laser has been used for Fourier transform-Raman scattering measurements. Raman scattering measurements with different excitation sources have revealed that the excitation energy is the decisive mechanism on the nature of the Raman scattering spectrum. When the excitation energy is close to the electronic band gap energy of any constituent semiconductor materials in the sample, electronic transition dominates the spectrum, leading to a very broad peak. In the condition that the excitation energy is much higher than the band gap energy, only vibrational modes contribute to the Raman scattering spectrum of the samples. Line shapes of the Raman scattering spectrum with the 785 and 1064 nm lines of lasers have been observed to be very broad peaks, whose absolute peak energy values are in good agreement with the ones obtained from photoluminescence measurements. On the other hand, Raman scattering spectrum with the 532 nm line has exhibited only vibrational modes. As a complementary tool of Raman scattering measurements with the excitation source of 532 nm, which shows weak vibrational transitions, attenuated total reflectance infrared spectroscopy has been also carried out. The results exhibited that the nature of the Raman scattering spectrum is strongly excitation energy-dependent, and with suitable excitation energy, electronic and/or vibrational transitions can be investigated. PMID:23190628

  14. The Energy-Dependent X-Ray Timing Characteristics of the Narrow Line Seyfert 1 MKN 766

    NASA Technical Reports Server (NTRS)

    Markowitz, A.; Papadakis, I.; Arevalo, P.; Turner, T. J.; Miller, L.; Reeves, J. N.

    2007-01-01

    We present the energy-dependent power spectral density (PSD) and cross-spectral properties of Mkn 766, obtained from combining data obtained during an XMM-Newton observation spanning six revolutions in 2005 with data obtained from an XMM-Newton long-look in 2001. The PSD shapes and rms-flux relations are found to be consistent between the 2001 and 2005 observations, suggesting the 2005 observation is simply a low-flux extension of the 2001 observation and permitting us to combine the two data sets. The resulting PSD has the highest temporal frequency resolution for any AGN PSD measured to date. Applying a broken power-law model yields break frequencies which increase in temporal frequency with photon energy. Obtaining a good fit when assuming energy-independent break frequencies requires the presence of a Lorentzian at 4.6 +/- 0.4 x 10(exp -4)Hz whose strength increases with photon energy, a behavior seen in black hole X-ray binaries. The cross-spectral properties are measured; temporal frequency-dependent soft-to-hard time lags are detected in this object for the first time. Cross-spectral results are consistent with those for other accreting black hole systems. The results are discussed in the context of several variability models, including those based on inwardly-propagating viscosity variations in the accretion disk.

  15. X-ray Variability Characteristics of the Narrow line SEYFERT 1 MKN 766 I: Energy Dependent Timing Properties

    NASA Technical Reports Server (NTRS)

    Markowitz, A.; Turner, T. J.; Papadakis, I.; Arevalo, P.; Reeves, J. N.; Miller, L.

    2007-01-01

    We present the energy-dependent power spectral density (PSD) and cross-spectral properties of Mkn 766 obtained from a six-revolution XMM-Newton observation in 2005. The resulting PSDs, which have highest temporal frequency resolution for an AGN PSD to date, show breaks which increase in temporal frequency as photon energy increases; break frequencies differ by an average of approx.0.4 in the log between the softest and hardest bands. The consistency of the 2001 and 2005 observations variability properties, namely PSD shapes and the linear rms-flux relation, suggests the 2005 observation is simply a low-flux extension of the 2001 observation. The coherence function is measured to be approx.0.6-0.9 at temporal frequencies below the PSD break, and is lower for relatively larger energy band separation; coherence also drops significantly towards zero above the PSD break frequency. Temporal frequency-dependent soft-to-hard time lags are detected in this object for the first time: lags increase towards longer time scales and as energy separation increases. Cross-spectral properties are the thus consistent with previous measurements for Mkn 766 (Vaughan & Fabian 2003) and other accreting black hole systems. The results are discussed in the context of several variability models, including those based on inwardly-propagating viscosity variations in the accretion disk.

  16. Comparison of modeled and observed environmental influences on the stable oxygen and hydrogen isotope composition of leaf water in Phaseolus vulgaris L

    SciTech Connect

    Flanagan, L.B.; Comstock, J.P.; Ehleringer, J.R. )

    1991-06-01

    In this paper the authors describe how a model of stable isotope fractionation processes, originally developed by H. Craig and L.I. Gordon for evaporation of water from the ocean, can be applied to leaf transpiration. The original model was modified to account for turbulent conditions in the leaf boundary layer. Experiments were conducted to test the factors influencing the stable isotopic composition of leaf water under controlled environment conditions. At steady state, the observed leaf water isotopic composition was enriched above that of stem water with the extent of the enrichment dependent on the leaf-air vapor pressure difference (VPD) and the isotopic composition of atmospheric water vapor (AMV). The higher the VPD, the larger was the observed heavy isotope content of leaf water. At a constant VPD, leaf water was relatively enriched in heavy isotopes when exposed to AWV with a large heavy isotope composition. However, the observed heavy isotope composition of leaf water was always less than that predicted by the model. The extent of the discrepancy between the modeled and observed leaf water isotopic composition was a strong linear function of the leaf transpiration rate.

  17. Effect of target composition on the emission enhancement observed in Double-Pulse Laser-Induced Breakdown Spectroscopy

    NASA Astrophysics Data System (ADS)

    Cristo Foretti, G.; Legnaioli, S.; Palleschi, V.; Salvetti, A.; Tognoni, E.

    2008-02-01

    The effect of the matrix composition on the emission enhancement observed in Double-Pulse (DP) Laser-Induced Breakdown Spectroscopy (LIBS) was studied for several pure metal targets (Al, Au, Co, Cu, Fe, Mn, Mo, Ni, Pb, Pt, Si and W). The measurements were performed in air by using a dual-pulse Nd:YAG ns laser emitting 60mJ pulses at 1064nm wavelength. The measurement of the emission enhancement for neutral and ionic lines of all the samples showed a wide range of results. Very low enhancement was observed in Pb, Ni and Mn while the highest values of enhancement were obtained in Cu, Al and Au. The space-averaged thermodynamic parameters of the induced plasmas in DP and in SP LIBS were calculated and the enhancement of ablated atomized mass in DP case was spectroscopically estimated in all the targets. A correlation seems to exist between the ablated atomized mass enhancement and the plasma temperature increase in the DP configuration. An attempt was made to correlate the increase of these two quantities with the melting point and heat, boiling point and heat, reflectivity and ionization energy of the metal. No evident correlation was found. At the opposite, a correlation was observed between the ablated atomized mass enhancement and the thermal diffusivity of the metal. A simple picture is proposed to explain the experimental findings. It is hypothesized that different mass ablation mechanisms prevail depending on the experimental configuration. It may be expected that in the SP case mass ablation is dominated by vaporization, while in the DP case it is dominated by phase explosion and/or melt expulsion.

  18. VIRTIS/Rosetta Observes Comet 67P/Churyumov-Gerasimenko: Nucleus and Coma Derived Composition and Physical Properties.

    NASA Astrophysics Data System (ADS)

    Capaccioni, F.; Filacchione, G.; Erard, S.; Arnold, G.; De Sanctis, M. C.; Bockelée-Morvan, D.; Leyrat, C.; Tosi, F.; Ciarniello, M.; Raponi, A.; Migliorini, A.; Quirico, E.; Rinaldi, G.; Schmitt, B.; Carlson, R. W.; Combi, M. R.; Fink, U.; Tozzi, G. P.; Palomba, E.; Longobardo, A.; Formisano, M.; Debout, V.; Drossart, P.; Piccioni, G.; Fougere, N.

    2015-12-01

    The paper will describe the major results obtained throughout the nominal mission by the instrument VIRTIS (Visible, Infrared and Thermal Imaging Spectrometer), the dual channel spectrometer onboard Rosetta, on the surface composition and thermal properties of the nucleus of comet 67P/Churyumov-Gerasimenko and on the 2D distribution of H2O and CO2 in the coma. VIRTIS is a dual channel spectrometer; VIRTIS-M (M for Mapper) is a hyper spectral imager covering a wide spectral range from 0.25 through 5μm. VIRTIS-M uses a slit and a scan mirror to generate images with spatial resolution of 250 μrad over a FOV of 3.7°. The second channel is VIRTIS-H (H for High-resolution), a point spectrometer with high spectral resolution (λ/Δλ=3000 @3μm) in the range 2-5 μm. The nucleus observations have been performed in a wide range of conditions with best spatial resolution of 2.5m. The surface temperature has been determined since the first distant observations when the nucleus filled one single VIRTIS-M pixel and continuously monitored since. Maximum temperature determined until April 2015 are as high as 300K at the subsolar point. Modeling of the thermophysical properties allowed to derive the thermal inertia of the crust. The VIRTIS composition analysis has showed evidence of carbon-bearing compounds on the nucleus of the comet 67P/Churyumov-Gerasimenko. The very low reflectance of the nucleus (normal albedo of 0.060 ± 0.003 at 0.55 μm), the spectral slopes in VIS and IR ranges (5-25 and 1.5-5 % kÅ-1) and the broad absorption feature in the 2.9-3.6 μm range present across the entire illuminated surface, are compatible with a surface crust made of a complex mixture of dark disordered poly-aromatic compounds, opaque minerals and several chemical species containing: -COOH, CH2 / CH3, -OH (in Alcohols) and possibly NH4+. Both channels are contributing to the determination of the spatial distribution of H2O and CO2 in the coma; their abundances as a function of altitude

  19. Energy dependence of r.m.s amplitude of low frequency broadband noise and kHz quasi periodic oscillations in 4U 1608-52

    NASA Astrophysics Data System (ADS)

    Mandal, Soma

    2016-07-01

    The neutron star low mass X-ray binary 4U 1608-52 is known to show kHz QPOs as well as low frequency broad band noise. The energy dependence of the fractional r.m.s of these variations reflect the underlying radiative mechanism responsible for the phenomena. In this work we compute the energy depedence for 26 instances of kHz QPO observed by RXTE. We typically find as reported before, that the r.m.s increases with energy with slope of ˜0.5. This indicates that the variation is in the hot thermal compotonization component and in particular the QPO is likely to be driven by variation in the thermal heating rate of the hot plasma. For the same data, we compute the energy dependent r.m.s variability of the low frequency broad band noise component by considering the light curves. In contrast to the behaviour seen for the kHz QPO, the energy dependence is nearly flat i.e. the r.m.s. is energy independent. This indicates that the driver here may be the soft photon source. Thus the radiative mechanism driving the low frequency broad band noise and the high frequency QPO are different in nature.

  20. 3-D multiobservable probabilistic inversion for the compositional and thermal structure of the lithosphere and upper mantle. I: a priori petrological information and geophysical observables

    NASA Astrophysics Data System (ADS)

    Afonso, J. C.; Fullea, J.; Griffin, W. L.; Yang, Y.; Jones, A. G.; D. Connolly, J. A.; O'Reilly, S. Y.

    2013-05-01

    Traditional inversion techniques applied to the problem of characterizing the thermal and compositional structure of the upper mantle are not well suited to deal with the nonlinearity of the problem, the trade-off between temperature and compositional effects on wave velocities, the nonuniqueness of the compositional space, and the dissimilar sensitivities of physical parameters to temperature and composition. Probabilistic inversions, on the other hand, offer a powerful formalism to cope with all these difficulties, while allowing for an adequate treatment of the intrinsic uncertainties associated with both data and physical theories. This paper presents a detailed analysis of the two most important elements controlling the outputs of probabilistic (Bayesian) inversions for temperature and composition of the Earth's mantle, namely the a priori information on model parameters, ρ(m), and the likelihood function, L(m). The former is mainly controlled by our current understanding of lithosphere and mantle composition, while the latter conveys information on the observed data, their uncertainties, and the physical theories used to relate model parameters to observed data. The benefits of combining specific geophysical datasets (Rayleigh and Love dispersion curves, body wave tomography, magnetotelluric, geothermal, petrological, gravity, elevation, and geoid), and their effects on L(m), are demonstrated by analyzing their individual and combined sensitivities to composition and temperature as well as their observational uncertainties. The dependence of bulk density, electrical conductivity, and seismic velocities to major-element composition is systematically explored using Monte Carlo simulations. We show that the dominant source of uncertainty in the identification of compositional anomalies within the lithosphere is the intrinsic nonuniqueness in compositional space. A general strategy for defining ρ(m) is proposed based on statistical analyses of a large database

  1. In situ observations of meteor smoke particles (MSP) during the Geminids 2010: constraints on MSP size, work function and composition

    NASA Astrophysics Data System (ADS)

    Rapp, M.; Plane, J. M. C.; Strelnikov, B.; Stober, G.; Ernst, S.; Hedin, J.; Friedrich, M.; Hoppe, U.-P.

    2012-12-01

    We present in situ observations of meteoric smoke particles (MSP) obtained during three sounding rocket flights in December 2010 in the frame of the final campaign of the Norwegian-German ECOMA project (ECOMA = Existence and Charge state Of meteoric smoke particles in the Middle Atmosphere). The flights were conducted before, at the maximum activity, and after the decline of the Geminids which is one of the major meteor showers over the year. Measurements with the ECOMA particle detector yield both profiles of naturally charged particles (Faraday cup measurement) as well as profiles of photoelectrons emitted by the MSPs due to their irradiation by photons of a xenon-flash lamp. The column density of negatively charged MSPs decreased steadily from flight to flight which is in agreement with a corresponding decrease of the sporadic meteor flux recorded during the same period. This implies that the sporadic meteors are a major source of MSPs while the additional influx due to the shower meteors apparently did not play any significant role. Surprisingly, the profiles of photoelectrons are only partly compatible with this observation: while the photoelectron current profiles obtained during the first and third flight of the campaign showed a qualitatively similar behaviour as the MSP charge density data, the profile from the second flight (i.e., at the peak of the Geminids) shows much smaller photoelectron currents. This may tentatively be interpreted as a different MSP composition (and, hence, different photoelectric properties) during this second flight, but at this stage we are not in a position to conclude that there is a cause and effect relation between the Geminids and this observation. Finally, the ECOMA particle detector used during the first and third flight employed three instead of only one xenon flash lamp where each of the three lamps used for one flight had a different window material resulting in different cut off wavelengths for these three lamp types

  2. A model for radial dike emplacement in composite cones based on observations from Summer Coon volcano, Colorado, USA

    USGS Publications Warehouse

    Poland, Michael P.; Moats, W.P.; Fink, J.H.

    2008-01-01

    We mapped the geometry of 13 silicic dikes at Summer Coon, an eroded Oligocene stratovolcano in southern Colorado, to investigate various characteristics of radial dike emplacement in composite volcanoes. Exposed dikes are up to about 7 km in length and have numerous offset segments along their upper peripheries. Surprisingly, most dikes at Summer Coon increase in thickness with distance from the center of the volcano. Magma pressure in a dike is expected to lessen away from the pressurized source region, which would encourage a blade-like dike to decrease in thickness with distance from the center of the volcano. We attribute the observed thickness pattern as evidence of a driving pressure gradient, which is caused by decreasing host rock shear modulus and horizontal stress, both due to decreasing emplacement depths beneath the sloping flanks of the volcano. Based on data from Summer Coon, we propose that radial dikes originate at depth below the summit of a host volcano and follow steeply inclined paths towards the surface. Near the interface between volcanic cone and basement, which may represent a neutral buoyancy surface or stress barrier, magma is transported subhorizontally and radially away from the center of the volcano in blade-like dikes. The dikes thicken with increasing radial distance, and offset segments and fingers form along the upper peripheries of the intrusions. Eruptions may occur anywhere along the length of the dikes, but the erupted volume will generally be greater for dike-fed eruptions far from the center of the host volcano owing to the increase in driving pressure with distance from the source. Observed eruptive volumes, vent locations, and vent-area intrusions from inferred post-glacial dike-fed eruptions at Mount Adams, Washington, USA, support the proposed model. Hazards associated with radial dike emplacement are therefore greater for longer dikes that propagate to the outer flanks of a volcano. ?? Springer-Verlag 2007.

  3. Nitrification in the euphotic zone as evidenced by nitrate dual isotopic composition: Observations from Monterey Bay, California

    USGS Publications Warehouse

    Wankel, Scott D.; Kendall, C.; Pennington, J.T.; Chavez, F.P.; Paytan, A.

    2007-01-01

    Coupled measurements of nitrate (NO3-), nitrogen (N), and oxygen (O) isotopic composition (??15NNO3 and ??18ONO3) were made in surface waters of Monterey Bay to investigate multiple N cycling processes occurring within surface waters. Profiles collected throughout the year at three sites exhibit a wide range of values, suggesting simultaneous and variable influence of both phytoplankton NO3- assimilation and nitrification within the euphotic zone. Specifically, increases ??18ONO3 were consistently greater than those in ??15NN03. A coupled isotope steady state box model was used to estimate the amount of NO3- supplied by nitrification in surface waters relative to that supplied from deeper water. The model highlights the importance of the branching reaction during ammonium (NH4+) consumption, in which NH4+ either serves as a substrate for regenerated production or for nitrification. Our observations indicate that a previously unrecognized proportion of nitrate-based productivity, on average 15 to 27%, is supported by nitrification in surface waters and should not be considered new production. This work also highlights the need for a better understanding of isotope effects of NH4+ oxidation, NH4+ assimilation, and NO4+ assimilation in marine environments.

  4. Analysis of incident-energy dependence of delayed neutron yields in actinides

    SciTech Connect

    Nasir, Mohamad Nasrun bin Mohd Metorima, Kouhei Ohsawa, Takaaki Hashimoto, Kengo

    2015-04-29

    The changes of delayed neutron yields (ν{sub d}) of Actinides have been analyzed for incident energy up to 20MeV using realized data of precursor after prompt neutron emission, from semi-empirical model, and delayed neutron emission probability data (P{sub n}) to carry out a summation method. The evaluated nuclear data of the delayed neutron yields of actinide nuclides are still uncertain at the present and the cause of the energy dependence has not been fully understood. In this study, the fission yields of precursor were calculated considering the change of the fission fragment mass yield based on the superposition of fives Gaussian distribution; and the change of the prompt neutrons number associated with the incident energy dependence. Thus, the incident energy dependent behavior of delayed neutron was analyzed.The total number of delayed neutron is expressed as ν{sub d}=∑Y{sub i} • P{sub ni} in the summation method, where Y{sub i} is the mass yields of precursor i and P{sub ni} is the delayed neutron emission probability of precursor i. The value of Y{sub i} is derived from calculation of post neutron emission mass distribution using 5 Gaussian equations with the consideration of large distribution of the fission fragments. The prompt neutron emission ν{sub p} increases at higher incident-energy but there are two different models; one model says that the fission fragment mass dependence that prompt neutron emission increases uniformly regardless of the fission fragments mass; and the other says that the major increases occur at heavy fission fragments area. In this study, the changes of delayed neutron yields by the two models have been investigated.

  5. Energy-dependent branching between fluorescence and singlet exciton dissociation in sexithienyl thin films

    NASA Astrophysics Data System (ADS)

    Dippel, O.; Brandl, V.; Bässler, H.; Danieli, R.; Zamboni, R.; Taliani, C.

    1993-12-01

    The fluorescence yield of thin films of sexithienyl drops rapidly above the S 1←S 0 absorption edge while the yield of photocarrier generation increases simultaneously. This unusual behavior of a molecular solid is interpreted in terms of an energy-dependent branching between fluorescence and dissociation of a singlet excitation into a weakly bound electron—hole pair. This is shown to be a characteristic feature of a disordered system in which the energy levels of both neutral and charged excitations are subject to inhomogeneous broadening. In T6 the latter arises from torsional displacement of the thienylene moities.

  6. Level-energy-dependent mean velocities of excited tungsten atoms sputtered by krypton-ion bombardment

    SciTech Connect

    Nogami, Keisuke; Sakai, Yasuhiro; Mineta, Shota; Kato, Daiji; Murakami, Izumi; Sakaue, Hiroyuki A.; Kenmotsu, Takahiro; Furuya, Kenji; Motohashi, Kenji

    2015-11-15

    Visible emission spectra were acquired from neutral atoms sputtered by 35–60 keV Kr{sup +} ions from a polycrystalline tungsten surface. Mean velocities of excited tungsten atoms in seven different 6p states were also obtained via the dependence of photon intensities on the distance from the surface. The average velocities parallel to the surface normal varied by factors of 2–4 for atoms in the different 6p energy levels. However, they were almost independent of the incident ion kinetic energy. The 6p-level energy dependence indicated that the velocities of the excited atoms were determined by inelastic processes that involve resonant charge exchange.

  7. The energy dependence of the pp {yields} K{sup +}n{Sigma}{sup +} reaction

    SciTech Connect

    Valdau, Yu.

    2011-10-24

    The energy dependence of the total cross section for the pp {yields} K{sup +}n{Sigma}{sup +} reaction has been investigated at the magnetic spectrometer COSY-ANKE. Signals from the production of the {Sigma}{sup +} hyperon were searched for in three simultaneously measured spectra. The values obtained for the total production cross section {sigma}({Sigma}{sup +}) are slightly below those of {sigma}({Sigma}{sup 0}) at the same excess energies. They follow a phase space dependence and do not show any evidence for strong threshold effects or a significant n{Sigma}{sup +} final state interaction.

  8. Plasma structure and energy dependence in a magnetic thrust chamber system

    NASA Astrophysics Data System (ADS)

    Morita, T.; Yamamoto, N.; Kawashima, R.; Saito, N.; Edamoto, M.; Fujioka, S.; Itadani, Y.; Johzaki, T.; Miura, S.; Mori, Y.; Nishimura, H.; Sunahara, A.; Yogo, A.; Nakashima, H.

    2016-05-01

    We demonstrate a magnetic thrust chamber system, in which an expanding plasma is controlled by an external magnetic field to produce a thrust. The plasma structure and energy dependences are discussed in terms of the drive laser energy and magnetic field strength. The density distribution from two different experiments show identical structure despite the laser energy is different by two order of magnitude when the ratio of magnetic field to plasma energy is more or less same. The experimental results indicate that this ratio is one of the essential factors to extrapolate the plasma dynamics for much larger energy such as inertial confinement fusion plasmas.

  9. Scaling-law for the energy dependence of anatomic power spectrum in dedicated breast CT

    SciTech Connect

    Vedantham, Srinivasan; Shi, Linxi; Glick, Stephen J.; Karellas, Andrew

    2013-01-15

    Purpose: To determine the x-ray photon energy dependence of the anatomic power spectrum of the breast when imaged with dedicated breast computed tomography (CT). Methods: A theoretical framework for scaling the empirically determined anatomic power spectrum at one x-ray photon energy to that at any given x-ray photon energy when imaged with dedicated breast CT was developed. Theory predicted that when the anatomic power spectrum is fitted with a power curve of the form k f{sup -{beta}}, where k and {beta} are fit coefficients and f is spatial frequency, the exponent {beta} would be independent of x-ray photon energy (E), and the amplitude k scales with the square of the difference in energy-dependent linear attenuation coefficients of fibroglandular and adipose tissues. Twenty mastectomy specimens based numerical phantoms that were previously imaged with a benchtop flat-panel cone-beam CT system were converted to 3D distribution of glandular weight fraction (f{sub g}) and were used to verify the theoretical findings. The 3D power spectrum was computed in terms of f{sub g} and after converting to linear attenuation coefficients at monoenergetic x-ray photon energies of 20-80 keV in 5 keV intervals. The 1D power spectra along the axes were extracted and fitted with a power curve of the form k f{sup -{beta}}. The energy dependence of k and {beta} were analyzed. Results: For the 20 mastectomy specimen based numerical phantoms used in the study, the exponent {beta} was found to be in the range of 2.34-2.42, depending on the axis of measurement. Numerical simulations agreed with the theoretical predictions that for a power-law anatomic spectrum of the form k f{sup -{beta}}, {beta} was independent of E and k(E) =k{sub 1}[{mu}{sub g}(E) -{mu}{sub a}(E)]{sup 2}, where k{sub 1} is a constant, and {mu}{sub g}(E) and {mu}{sub a}(E) represent the energy-dependent linear attenuation coefficients of fibroglandular and adipose tissues, respectively. Conclusions: Numerical

  10. Energy Dependence of Particle Multiplicities in Central Au+Au Collisions

    NASA Astrophysics Data System (ADS)

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

    2002-01-01

    We present the first measurement of the pseudorapidity density of primary charged particles in Au+Au collisions at (sNN) = 200 GeV. For the 6% most central collisions, we obtain dNch/dη\\|\\|η\\|<1 = 650+/-35(syst). Compared to collisions at (sNN) = 130 GeV, the highest energy studied previously, an increase by a factor of 1.14+/-0.05 at 90% confidence level, is found. The energy dependence of the pseudorapidity density is discussed in comparison with data from proton-induced collisions and theoretical predictions.