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Sample records for observed energy-dependent composition

  1. Role of galactic sources and magnetic fields in forming the observed energy-dependent composition of ultrahigh-energy cosmic rays.

    PubMed

    Calvez, Antoine; Kusenko, Alexander; Nagataki, Shigehiro

    2010-08-27

    Recent results from the Pierre Auger Observatory, showing energy-dependent chemical composition of ultrahigh-energy cosmic rays (UHECRs) with a growing fraction of heavy elements at high energies, suggest a possible non-negligible contribution of the Galactic sources. We show that, in the case of UHECRs produced by gamma-ray bursts or rare types of supernova explosions that took place in the Milky Way in the past, the change in UHECR composition can result from the difference in diffusion times for different species. The anisotropy in the direction of the Galactic center is expected to be a few per cent on average, but the locations of the most recent or closest bursts can be associated with observed clusters of UHECRs.

  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. 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.

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

    PubMed

    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.

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

    DOE PAGES

    Ripoll, J. -F.; Reeves, Geoffrey D.; Cunningham, Gregory Scott; ...

    2016-06-11

    Here, 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 andmore » (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.« less

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

    SciTech Connect

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

    2016-06-11

    Here, 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.

  7. A Search for Spectral Hysteresis and Energy-dependent Time Lags from X-Ray and TeV Gamma-Ray Observations of Mrk 421

    NASA Astrophysics Data System (ADS)

    Abeysekara, A. U.; Archambault, S.; Archer, A.; Benbow, W.; Bird, R.; Buchovecky, M.; Buckley, J. H.; Bugaev, V.; Cardenzana, J. V.; Cerruti, M.; Chen, X.; Ciupik, L.; Connolly, M. P.; Cui, W.; Eisch, J. D.; Falcone, A.; Feng, Q.; Finley, J. P.; Fleischhack, H.; Flinders, A.; Fortson, L.; Furniss, A.; Griffin, S.; Håkansson, M. HN.; Hanna, D.; Hervet, O.; Holder, J.; Humensky, T. B.; Kaaret, P.; Kar, P.; Kertzman, M.; Kieda, D.; Krause, M.; Kumar, S.; Lang, M. J.; Maier, G.; McArthur, S.; McCann, A.; Meagher, K.; Moriarty, P.; Mukherjee, R.; Nieto, D.; Ong, S. OR. A.; Otte, A. N.; Park, N.; Pelassa, V.; Pohl, M.; Popkow, A.; Pueschel, E.; Ragan, K.; Reynolds, P. T.; Richards, G. T.; Roache, E.; Sadeh, I.; Santander, M.; Sembroski, G. H.; Shahinyan, K.; Staszak, D.; Telezhinsky, I.; Tucci, J. V.; Tyler, J.; Wakely, S. P.; Weinstein, A.; Wilhelm, A.; Williams, D. A.; the VERITAS Collaboration; Ahnen, M. L.; Ansoldi, S.; Antonelli, L. A.; Antoranz, P.; Arcaro, C.; Babic, A.; Banerjee, B.; Bangale, P.; Barres de Almeida, U.; Barrio, J. A.; Becerra González, J.; Bednarek, W.; Bernardini, E.; Berti, A.; Biasuzzi, B.; Biland, A.; Blanch, O.; Bonnefoy, S.; Bonnoli, G.; Borracci, F.; Bretz, T.; Carosi, R.; Carosi, A.; Chatterjee, A.; Colin, P.; Colombo, E.; Contreras, J. L.; Cortina, J.; Covino, S.; Cumani, P.; Da Vela, P.; Dazzi, F.; De Angelis, A.; De Lotto, B.; de Oña Wilhelmi, E.; Di Pierro, F.; Doert, M.; Domínguez, A.; Dominis Prester, D.; Dorner, D.; Doro, M.; Einecke, S.; Eisenacher Glawion, D.; Elsaesser, D.; Engelkemeier, M.; Fallah Ramazani, V.; Fernández-Barral, A.; Fidalgo, D.; Fonseca, M. V.; Font, L.; Fruck, C.; Galindo, D.; García López, R. J.; Garczarczyk, M.; Gaug, M.; Giammaria, P.; Godinović, N.; Gora, D.; Guberman, D.; Hadasch, D.; Hahn, A.; Hassan, T.; Hayashida, M.; Herrera, J.; Hose, J.; Hrupec, D.; Hughes, G.; Idec, W.; Kodani, K.; Konno, Y.; Kubo, H.; Kushida, J.; Lelas, D.; Lindfors, E.; Lombardi, S.; Longo, F.; López, M.; López-Coto, R.; Majumdar, P.; Makariev, M.; Mallot, K.; Maneva, G.; Manganaro, M.; Mannheim, K.; Maraschi, L.; Marcote, B.; Mariotti, M.; Martínez, M.; Mazin, D.; Menzel, U.; Mirzoyan, R.; Moralejo, A.; Moretti, E.; Nakajima, D.; Neustroev, V.; Niedzwiecki, A.; Nievas Rosillo, M.; Nilsson, K.; Nishijima, K.; Noda, K.; Nogués, L.; Nöthe, M.; Paiano, S.; Palacio, J.; Palatiello, M.; Paneque, D.; Paoletti, R.; Paredes, J. M.; Paredes-Fortuny, X.; Pedaletti, G.; Peresano, M.; Perri, L.; Persic, M.; Poutanen, J.; Prada Moroni, P. G.; Prandini, E.; Puljak, I.; Garcia, J. R.; Reichardt, I.; Rhode, W.; Ribó, M.; Rico, J.; Saito, T.; Satalecka, K.; Schroeder, S.; Schweizer, T.; Shore, S. N.; Sillanpää, A.; Sitarek, J.; Snidaric, I.; Sobczynska, D.; Stamerra, A.; Strzys, M.; Surić, T.; Takalo, L.; Tavecchio, F.; Temnikov, P.; Terzić, T.; Tescaro, D.; Teshima, M.; Torres, D. F.; Torres-Albà, N.; Toyama, T.; Treves, A.; Vanzo, G.; Vazquez Acosta, M.; Vovk, I.; Ward, J. E.; Will, M.; Wu, M. H.; Zanin, R.; the MAGIC Collaboration; Hovatta, T.; de la Calle Perez, I.; Smith, P. S.; Racero, E.; Baloković, M.

    2017-01-01

    Blazars are variable emitters across all wavelengths over a wide range of timescales, from months down to minutes. It is therefore essential to observe blazars simultaneously at different wavelengths, especially in the X-ray and gamma-ray bands, where the broadband spectral energy distributions usually peak. In this work, we report on three “target-of-opportunity” observations of Mrk 421, one of the brightest TeV blazars, triggered by a strong flaring event at TeV energies in 2014. These observations feature long, continuous, and simultaneous exposures with XMM-Newton (covering the X-ray and optical/ultraviolet bands) and VERITAS (covering the TeV gamma-ray band), along with contemporaneous observations from other gamma-ray facilities (MAGIC and Fermi-Large Area Telescope) and a number of radio and optical facilities. Although neither rapid flares nor significant X-ray/TeV correlation are detected, these observations reveal subtle changes in the X-ray spectrum of the source over the course of a few days. We search the simultaneous X-ray and TeV data for spectral hysteresis patterns and time delays, which could provide insight into the emission mechanisms and the source properties (e.g., the radius of the emitting region, the strength of the magnetic field, and related timescales). The observed broadband spectra are consistent with a one-zone synchrotron self-Compton model. We find that the power spectral density distribution at ≳4 × 10‑4 Hz from the X-ray data can be described by a power-law model with an index value between 1.2 and 1.8, and do not find evidence for a steepening of the power spectral index (often associated with a characteristic length scale) compared to the previously reported values at lower frequencies.

  8. Energy dependence of hadronic activity

    NASA Astrophysics Data System (ADS)

    Gabriel, T. A.; Groom, D. E.; Job, P. K.; Mokhov, N. V.; Stevenson, G. R.

    1994-01-01

    Two features of high-energy hadronic cascades have long been known to shielding specialists: a) in a high-energy hadronic cascade in a given material (incident E ≳ 10 GeV), the relative abundance and spectrum of each hadronic species responsible for most of the energy deposition is independent of the energy or species of the incident hadron, and b) because π0 production bleeds off more and more energy into the electromagnetic sector as the energy of the incident hadron increases, the absolute level of this low-energy hadronic activity ( E ≲ 1 GeV) rises less rapidly than the incident energy, and in fact rises very nearly as a power of the incident energy. Both features are of great importance in hadron calorimetry, where it is the "universal spectrum" which makes possible the definition of an intrinsic {e}/{h}, and the increasing fraction of the energy going into π0's which leads to the energy dependence of {e}/{π}. We present evidence for the "universal spectrum," and use an induction argument and simulation results to demonstrate that the low-energy activity ss Em, with 0.80 ≲ m ≲ 0.85. The hadronic activity produced by incident pions is 15-20% less than that initiated by protons.

  9. Terrestrial planet composition: simulation and observation

    NASA Astrophysics Data System (ADS)

    Carter-Bond, J.; Bolmont, E.; Raymond, S.

    2014-03-01

    As direct detection and examination of terrestrial exoplanets is not yet possible, we must persue alternative methods to constarin the types of planets likely to be found within extrasolar planetary systems and thus guide future missions. Such studies cannot be undertaken by transit surveys. Instead, secondary sources must be utilized. In addition to simultions of terrestrial planet formation, based on spectroscopic observations of known stars, observations of polluted white dwarfs (e.g. Jura, M., & Xu, S. (2012); Gaensicke et al., (2013)) and simulations of the pollution of migrating gas giants may be utilized to determine the composition of solid bodies withn extrasolar planetary systems. Observations of polluted white dwarfs (e.g. Jura, M., & Xu, S. (2012); Gaensicke et al., (2013)) will be compared to simulations of the bulk composition of terrestrial planets (Carter-Bond et al. (2012)). Combining dynamical simulations of Carter-Bond et al. (2012) and Raymond et al. (2006) with spectrally-derived abundances for 15 planet-forming elements (H, C, N, O, Na, Mg, Al, Si, P, S, Ca, Ti, Cr, Fe and Ni), bulk compositions for simulated terrestrial planets have been obtained. This is the first time that compositional simulations can be compared with observations (albeit of a proxy for solid composition) and will be crucial for placing constraints on both the true diversity of planetary compositions expected to exist in extrasolar planetary systems and the simulations currently utilized. Simulations of the change in composition resulting from pollution of a gas giant as it migrates through a planetary system will also be presented. These simulations represent an as-yet untested approach to determining the solid composition within a planetary system. By simulating the amount and composition of material accreted by the gas giant (following Carter-Bond et al. (2012)), we will be able to determine what effect, if any, the accretion of solid material during migration has on

  10. 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.

  11. Solar cosmic ray composition above 10 MeV/nucleon and its energy dependence in the 4 August 1972 event. [including proton, helium, and Fe-group nuclei fluxes

    NASA Technical Reports Server (NTRS)

    Bertsch, D. L.; Biswas, S.; Reames, D. V.

    1974-01-01

    Observations of the proton, helium (C,N,O) and Fe-group nuclei fluxes made during the large 4 August 1972 solar particle event are presented. The results show a small, but significant variation of the composition of multicharged nuclei as a function of energy in the energy region above 10 MeV/nucleon. In particular, the He/(C,N,O) abundance ratio varies by a factor approximately 2 between 10 and 50 MeV/nucleon, and the Fe-group/(C,N,O) ratio suggests a similar variation. Abundance ratios from the 4 August 1972 event are compared as a function of energy with ratios measured in other solar events. At energies approximately greater than 50 MeV/nucleon, the He/(C,N,O) abundance ratio for August 1972 is consistent with all earlier measurements made above that energy.

  12. Applying supersymmetry to energy dependent potentials

    SciTech Connect

    Yekken, R.; Lassaut, M.; Lombard, R.J.

    2013-11-15

    We investigate the supersymmetry properties of energy dependent potentials in the D=1 dimensional space. We show the main aspects of supersymmetry to be preserved, namely the factorization of the Hamiltonian, the connections between eigenvalues and wave functions of the partner Hamiltonians. Two methods are proposed. The first one requires the extension of the usual rules via the concept of local equivalent potential. In this case, the superpotential becomes depending on the state. The second method, applicable when the potential depends linearly on the energy, is similar to what has been already achieved by means of the Darboux transform. -- Highlights: •Supersymmetry extended to energy dependent potentials. •Generalization of the concept of superpotential. •An alternative method used for linear E-dependence leads to the same results as Darboux transform.

  13. 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.

  14. Energy dependence of scatter components in multispectral PET imaging.

    PubMed

    Bentourkia, M; Msaki, P; Cadorette, J; Lecomte, R

    1995-01-01

    High resolution images in PET based on small individual detectors are obtained at the cost of low sensitivity and increased detector scatter. These limitations can be partially overcome by enlarging discrimination windows to include more low-energy events and by developing more efficient energy-dependent methods to correct for scatter radiation from all sources. The feasibility of multispectral scatter correction was assessed by decomposing response functions acquired in multiple energy windows into four basic components: object, collimator and detector scatter, and trues. The shape and intensity of these components are different and energy-dependent. They are shown to contribute to image formation in three ways: useful (true), potentially useful (detector scatter), and undesirable (object and collimator scatter) information to the image over the entire energy range. With the Sherbrooke animal PET system, restoration of detector scatter in every energy window would allow nearly 90% of all detected events to participate in image formation. These observations suggest that multispectral acquisition is a promising solution for increasing sensitivity in high resolution PET. This can be achieved without loss of image quality if energy-dependent methods are made available to preserve useful events as potentially useful events are restored and undesirable events removed.

  15. 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.

  16. Constraining photon mass by energy-dependent gravitational light bending

    NASA Astrophysics Data System (ADS)

    Qian, Lei

    2012-03-01

    In the standard model of particle physics, photons are massless particles with a particular dispersion relation. Tests of this claim at different scales are both interesting and important. Experiments in territory labs and several exterritorial tests have put some upper limits on photon mass, e.g., torsion balance experiment in the lab shows that photon mass should be smaller than 1.2 × 10-51g. In this work, this claim is tested at a cosmological scale by looking at strong gravitational lensing data available and an upper limit of 8.71 × 10-39g on photon mass is given. Observations of energy-dependent gravitational lensing with not yet available higher accuracy astrometry instruments may constrain photon mass better.

  17. Energy dependence of fusion cross sections

    SciTech Connect

    Bang, J.M.; Ferreira, L.S.; Maglione, E.; Hansteen, J.M.

    1996-01-01

    Observed enhancements of fusion cross sections at low energies are explained as caused by an underestimate of beam energy due to an overestimate of the stopping energy loss. {copyright} {ital 1996 The American Physical Society.}

  18. 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.

  19. The energy dependence of cosmic ray propagation at low energy

    NASA Technical Reports Server (NTRS)

    Garcia-Munoz, M.; Guzik, T. G.; Margolis, S. H.; Simpson, J. A.; Wefel, J. P.

    1982-01-01

    The interstellar propagation of cosmic rays is investigated using current 'best estimates' for the partial and total cross sections and their energy dependence and the current model of solar modulation. The experimental boron to carbon ratio is reproduced if the mean of the path length distribution decreases with decreasing energy below approximately 1 GeV/nucleon. This energy dependence is compared to shock acceleration models and dynamical halo models using different galactic wind velocities.

  20. Telescope Array UHECR composition measurement via stereoscopic fluorescence observation

    NASA Astrophysics Data System (ADS)

    Stroman, Thomas; Bergman, Douglas; Telescope Array Collaboration

    2016-03-01

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

  1. 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.

  2. 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).

  3. 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.

  4. Regulation by proteolysis: energy-dependent proteases and their targets.

    PubMed Central

    Gottesman, S; Maurizi, M R

    1992-01-01

    A number of critical regulatory proteins in both prokaryotic and eukaryotic cells are subject to rapid, energy-dependent proteolysis. Rapid degradation combined with control over biosynthesis provides a mechanism by which the availability of a protein can be limited both temporally and spatially. Highly unstable regulatory proteins are involved in numerous biological functions, particularly at the commitment steps in developmental pathways and in emergency responses. The proteases involved in energy-dependent proteolysis are large proteins with the ability to use ATP to scan for appropriate targets and degrade complete proteins in a processive manner. These cytoplasmic proteases are also able to degrade many abnormal proteins in the cell. PMID:1480111

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Implementation of Energy-Dependent Q Values for Fission

    SciTech Connect

    Beck, B; Brown, D A; Daffin, F; Hedstrom, J; Vogt, R

    2007-08-08

    We discuss how the fission Q values for {sup 235}U, {sup 238}U and {sup 239}Pu depend on the energy of the incident neutron. We then describe how these values have been implemented in mcfgen etc. This paper describes the calculation of energy-dependent fission Q values by Madland [1] and explains how it has been implemented in the ENDL database for use in the LLNL codes.

  11. Titan's Surface Composition from Cassini VIMS Solar Occultation Observations

    NASA Astrophysics Data System (ADS)

    McCord, Thomas; Hayne, Paul; Sotin, Christophe

    2013-04-01

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

  12. 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

  13. Exciton interference revealed by energy dependent exciton transfer rate for ring-structured molecular systems

    SciTech Connect

    Yan, Yun-An

    2016-01-14

    The quantum interference is an intrinsic phenomenon in quantum physics for photon and massive quantum particles. In principle, the quantum interference may also occur with quasi-particles, such as the exciton. In this study, we show how the exciton quantum interference can be significant in aggregates through theoretical simulations with hierarchical equations of motion. The systems under investigation are generalized donor-bridge-acceptor model aggregates with the donor consisting of six homogeneous sites assuming the nearest neighbor coupling. For the models with single-path bridge, the exciton transfer time only shows a weak excitation energy dependence. But models with double-path bridge have a new short transfer time scale and the excitation energy dependence of the exciton transfer time assumes clear peak structure which is detectable with today’s nonlinear spectroscopy. This abnormality is attributed to the exciton quantum interference and the condition for a clear observation in experiment is also explored.

  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. 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.

  16. Further development of the EUMETNET Composite Observing System (EUCOS)

    NASA Astrophysics Data System (ADS)

    Klink, S.; Dibbern, J.

    2009-09-01

    EUCOS, which stands for EUMETNET Composite Observing System, is a EUMETNET programme whose main objective is a central management of surface based operational observations on a European-wide scale serving the needs of regional scale NWP. EUMETNET is a consortium of currently 26 national meteorological services in Europe that provides a framework for different operational and developmental co-operative programmes between the services. The work content of the EUCOS Programme includes the management of the operational observing networks, through the E-AMDAR, E-ASAP, E-SURFMAR and E-WINPROF programmes. The coordination of NMSs owned territorial networks (e.g. radiosonde stations and synoptic stations), data quality monitoring, fault reporting and recovery, a studies programme for the evolution of the observing networks and liaison with other organisations like WMO are among the tasks of the programme. The current period of the EUCOS programme has a five year duration (2007-2011) and a two stage approach was proposed in the programme definition. During the transition phase 2007-2008 no new programmatic objectives had been set because amongst others the Space-Terrestrial (S-T) study which investigated the relative contributions of selected space based and ground based observing systems to the forecast skill of global and regional NWP models had to be finalised first. Based on the findings of this study EUCOS currently prepares a redesign of its upper-air network. The original EUCOS upper-air network design was prepared in 2000 in order to define a set of stations serving the common general NWP requirement. Additional considerations were to make it possible to supply a common set of performance standards across the territory of EUMETNET Members and to ensure that the radiosonde network interleaved with AMDAR airports. The EUCOS upper-air network now requires a redesign because of several reasons. There is a need to take into account the significant evolution of the AMDAR

  17. Examination of the energy dependence of the fusion process

    NASA Astrophysics Data System (ADS)

    Torabi, F.; Ghodsi, O. N.; Pahlavani, M. R.

    2017-03-01

    In this study, the role of bombarding energy in analyzing the interaction potentials and describing the densities of interacting nuclei during fusion is investigated. For this purpose, the fusion cross sections of the 40Ca+48Ca , 16O+92Zr , and 40Ca+90Zr systems are calculated by the use of potentials derived from the semiclassical Skyrme energy density functional and the coupled-channel formalism. The comparisons drawn between the theoretical fusion data and the experimental ones demonstrate the energy-dependence behavior of the potentials employed in the calculations. Considering this dependence, we also show the variations of the density parameters of the colliding nuclei with the bombarding energy. The obtained results indicate that with increasing energy, the fusion barrier heights increase, while the diffuseness parameters of the densities decrease.

  18. North-Polar Lunar Light Plains: Ages and Compositional Observations

    NASA Astrophysics Data System (ADS)

    Koehler, U.; Head, J. W., III; Neukum, G.; Wolf, U.

    1999-01-01

    Varying surface ages of lunar light plains in northern-nearside latitudes indicate an origin of these smooth terrae units not exclusively related to Imbrium and/or Orientale impact ejecta. and subsequent processes. Multispectral data seem to support a more diversified history for many of these plains. The nature, ages, stratigraphic position, composition, and mode of emplacement of lunar light plains have been discussed with controversy for more than three decades. Covering about 5% of the lunar terra surface, the relatively low albedo plains are the most distinctive terra landforms after the more crater-like ejecta of the fresh basins. Morphological properties, like their smoothness, lower crater densities, their superposition on the "Imbrian Sculpture," and frequent occurence as crater fill, are mare-like. Other features, such as relative (compared to mare basalts) high-albedo and geological/stratigraphical setting, are more highland-like. Not surprisingly, light plains were seen as both volcanic and impact related deposits. The Cayley Plains, a type locality in the central-nearside highlands, has been chosen as the landing site of the Apollo XVI mission partly to help resolve these interpretations. The astronauts collected samples - highly brecciated rocks - and concluded that the Cayley was indeed of impact origin. These findings have been extrapolated to stratigraphically similar plains units on the nearside, focusing on the Imbrium and Orientale impacts as responsible events for resurfacing terrae environment to form light plains. In addition, theoretical modeling mechanisms have been provided that could explain how basin and crater ejecta were able to make up for the smoothness of light plains by stirring up local material through secondary-impact related processes, or mega impact induced seismic shaking. However, subsequent age determinations showed that some light plains cannot be correlated to the Imbrium or Orientale event, the last two basin

  19. 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...

  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. 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.

  2. Observation of nonconventional spin waves in composite-fermion ferromagnets.

    PubMed

    Wurstbauer, U; Majumder, D; Mandal, S S; Dujovne, I; Rhone, T D; Dennis, B S; Rigosi, A F; Jain, J K; Pinczuk, A; West, K W; Pfeiffer, L N

    2011-08-05

    We find unexpected low energy excitations of fully spin-polarized composite-fermion ferromagnets in the fractional quantum Hall liquid, resulting from a complex interplay between a topological order manifesting through new energy levels and a magnetic order due to spin polarization. The lowest energy modes, which involve spin reversal, are remarkable in displaying unconventional negative dispersion at small momenta followed by a deep roton minimum at larger momenta. This behavior results from a nontrivial mixing of spin-wave and spin-flip modes creating a spin-flip excitonic state of composite-fermion particle-hole pairs. The striking properties of spin-flip excitons imply highly tunable mode couplings that enable fine control of topological states of itinerant two-dimensional ferromagnets.

  3. 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.

  4. Inelastic cotunneling with energy-dependent contact transmission

    NASA Astrophysics Data System (ADS)

    Blok, S.; Agundez Mojarro, R. R.; Maduro, L. A.; Blaauboer, M.; Van Der Molen, S. J.

    2017-03-01

    We investigate inelastic cotunneling in a model system where the charging island is connected to the leads through molecules with energy-dependent transmission functions. To study this problem, we propose two different approaches. The first is a pragmatic approach that assumes Lorentzian-like transmission functions that determine the transmission probability to the island. Using this model, we calculate current versus voltage (IV) curves for increasing resonance level positions of the molecule. We find that shifting the resonance energy of the molecule away from the Fermi energy of the contacts leads to a decreased current at low bias, but as bias increases, this difference decreases and eventually inverses. This is markedly different from IV behavior outside the cotunneling regime. The second approach involves multiple cotunneling where also the molecules are considered to be in the Coulomb blockade regime. We find here that when Ec≫eV ,kBT , the IV behavior approaches the original cotunneling behavior proposed by Averin and Nazarov [Phys. Rev. Lett. 65, 2446-2449 (1990)].

  5. 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.

  6. 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.

  7. 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

  8. Energy-dependent stability of Shewanella oneidensis MR-1 biofilms.

    PubMed

    Saville, Renee M; Rakshe, Shauna; Haagensen, Janus A J; Shukla, Soni; Spormann, Alfred M

    2011-07-01

    Stability and resistance to dissolution are key features of microbial biofilms. How these macroscopic properties are determined by the physiological state of individual biofilm cells in their local physical-chemical and cellular environment is largely unknown. In order to obtain molecular and energetic insight into biofilm stability, we investigated whether maintenance of biofilm stability is an energy-dependent process and whether transcription and/or translation is required for biofilm dissolution. We found that in 12-hour-old Shewanella oneidensis MR-1 biofilms, a reduction in cellular ATP concentration, induced either by oxygen deprivation or by addition of the inhibitor of oxidative phosphorylation carbonyl cyanide m-chlorophenylhydrazone (CCCP), dinitrophenol (DNP), or CN(-), resulted in massive dissolution. In 60-hour-old biofilms, the extent of uncoupler-induced cell loss was strongly attenuated, indicating that the integrity of older biofilms is maintained by means other than those operating in younger biofilms. In experiments with 12-hour-old biofilms, the transcriptional and translational inhibitors rifampin, tetracycline, and erythromycin were found to be ineffective in preventing energy starvation-induced detachment, suggesting that neither transcription nor translation is required for this process. Biofilms of Vibrio cholerae were also induced to dissolve upon CCCP addition to an extent similar to that in S. oneidensis. However, Pseudomonas aeruginosa and P. putida biofilms remained insensitive to CCCP addition. Collectively, our data show that metabolic energy is directly or indirectly required for maintaining cell attachment, and this may represent a common but not ubiquitous mechanism for stability of microbial biofilms.

  9. Energy dependence and angular dependence of an optically stimulated luminescence dosimeter in the mammography energy range.

    PubMed

    Kawaguchi, Ai; Matsunaga, Yuta; Suzuki, Shoichi; Chida, Koichi

    2017-03-01

    This study aimed to investigate the energy dependence and the angular dependence of commercially available optically stimulated luminescence (OSL) point dosimeters in the mammography energy range. The energy dependence was evaluated to calculate calibration factors (CFs). The half-value layer range was 0.31-0.60 mmAl (Mo/Mo 22-28 kV, Mo/Rh 28-32 kV, and W/Rh 30-34 kV at 2-kV intervals). Mo/Rh 28 kV was the reference condition. Angular dependence was tested by rotating the X-ray tube from -90° to 90° in 30° increments, and signal counts from angled nanoDots were normalized to the 0° signal counts. Angular dependence was compared with three tube voltage and target/filter combinations (Mo/Mo 26 kV, Mo/Rh 28 kV and W/Rh 32 kV). The CFs of energy dependence were 0.94-1.06. In Mo/Mo 26-28 kV and Mo/Rh 28-32 kV, the range of CF was 0.99-1.01, which was very similar. For angular dependence, the most deteriorated normalized values (Mo/Mo, 0.37; Mo/Rh, 0.43; and W/Rh, 0.58) were observed when the X-ray tube was rotated at a 90° angle, compared to 0°. The most angular dependences of ± 30°, 60°, and 90° decreased by approximately 4%, 14%, and 63% respectively. The mean deteriorated measurement 30° intervals from 0° to ± 30° was 2%, from ± 30° to ± 60° was 8%, and from ± 60° to ± 90° was 40%. The range of energy dependence in typical mammography energy range was not as much as that in general radiography and computed tomography. For accurate measurement using nanoDot, the tilt needs to be under 30°.

  10. 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...

  11. 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.

  12. Experimental Observations of Particle-hole Asymmetry for Composite Fermions

    NASA Astrophysics Data System (ADS)

    Liu, Yang

    In this talk, I will present our experimental study of the breaking of particle-hole symmetry for composite fermions (CFs), quasi-particles formed by attaching two flux quanta to each electron at large perpendicular magnetic fields. We measure the Fermi contour of the spin-polarized CFs near ν = 1 / 2 via commensurability oscillations, and find an asymmetry of the Fermi wave vector for ν < 1 / 2 and > 1 / 2 . In particular, we find that the deduced wave vector is smaller for ν > 1 / 2 compared to ν < 1 / 2 , and on both sides consistent with the density of minority carriers in the lowest Landau level. We also study the spin-polarization transitions of fractional quantum Hall states near ν = 3 / 2 and 1/2; these states are particle-hole conjugates of each other and are expected to have the same polarization energies. Our systematic results clearly show the transition energies are about three times larger for states near ν = 3 / 2 compared to those near ν = 1 / 2 . Work done in collaboration with D. Kamburov, M. A. Mueed, S. Hasdemir, A. Wojs, J.K. Jain, L.N. Pfeiffer, K.W. West, K.W. Baldwin, and M. Shayegan. We acknowledge support from the DOE, NSF, the Gordon and Betty Moore Foundation and the Keck Foundation. The experiments were partly performed at the National High Magnetic Field Laboratory.

  13. 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.

  14. 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.

  15. 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

  16. 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.

  17. 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.

  18. Excitation energy dependence of the level density parameter close to the doubly magic 208Pb

    NASA Astrophysics Data System (ADS)

    Roy, Pratap; Banerjee, K.; Bhattacharya, C.; Pandey, R.; Sen, A.; Manna, S.; Kundu, S.; Rana, T. K.; Ghosh, T. K.; Mukherjee, G.; Roy, T.; Dhal, A.; Dey, A.; Meena, J. K.; Saha, A. K.; Pandit, Deepak; Mukhopadhyay, S.; Bhattacharya, S.

    2016-12-01

    Neutron evaporation spectra have been measured from 4He+208Pb and 4He+209Bi reactions by using 4He-ion beams of several bombarding energies. Excitation-energy dependence of the level density parameter has been studied for the two systems in the excitation energy range of ˜18 -50 MeV. For both the reactions an overall reduction of the asymptotic level density parameter with increasing excitation energy (temperature) is observed. The trend of the data was compared with the Thomas-Fermi model predictions and found to be in reasonable agreement. The value of the shell damping parameter has been extracted from the lowest-energy data in the case of Po,211210 and At,212211 nuclei close to the Z =82 and N =126 shell closure, and it was found to be consistent with the recent measurement in the vicinity of doubly magic 208Pb nucleus.

  19. 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.

  20. Role of energy dependent interaction potential in sub-barrier fusion of S2814i +Z9040r system

    NASA Astrophysics Data System (ADS)

    Gautam, Manjeet Singh; Sharma, Manoj K.

    2015-08-01

    We have analyzed the importance of the inelastic surface vibrations of colliding nuclei in the sub-barrier fusion enhancement of S2814i +Z9040r system by using the energy dependent Woods-Saxon potential model (EDWSP model) in conjunction with one dimensional Wong formula and the coupled channel formulation using the code CCFULL. The multi-phonon vibrational states of colliding nuclei seem to impart significant contribution. The coupling between relative motion of reactants and these relevant channels in turn produce anomalously large sub-barrier fusion enhancement over the expectations of one dimensional barrier penetration model. Furthermore, the effects of coupling to inelastic surface excitations are imitated due to energy dependence in the Woods-Saxon potential. In EDWSP model calculations, a wide range of diffuseness parameter much larger than the elastic scattering predictions is needed to account the observed fusion enhancement in the close vicinity of Coulomb barrier.

  1. 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.

  2. Excitation-energy dependence of the giant dipole resonance width

    NASA Astrophysics Data System (ADS)

    Enders, G.; Berg, F. D.; Hagel, K.; Kühn, W.; Metag, V.; Novotny, R.; Pfeiffer, M.; Schwalb, O.; Charity, R. J.; Gobbi, A.; Freifelder, R.; Henning, W.; Hildenbrand, K. D.; Holzmann, R.; Mayer, R. S.; Simon, R. S.; Wessels, J. P.; Casini, G.; Olmi, A.; Stefanini, A. A.

    1992-07-01

    High-energy γ rays have been measured in coincidence with heavy fragents in deeply inelastic reactions of 136Xe+48Ti at 18.5 MeV/nucleon. The giant dipole resonance (GDR) strength function is deduced from an analysis of the photon spectra within the statistical model. The GDR width Γ is studied as a function of the fragment excitation energy E*. A saturation at about Γ=10 MeV is observed for E*/A>=1.0 MeV/nucleon.

  3. 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

  4. Energy dependence of hadron polarization in e+e-→h X at high energies

    NASA Astrophysics Data System (ADS)

    Chen, Kai-bao; Yang, Wei-hua; Zhou, Ya-jin; Liang, Zuo-tang

    2017-02-01

    The longitudinal polarization of a hyperon in e+e- annihilation at high energies depends on the longitudinal polarization of the quark produced at the e+e- annihilation vertex, whereas the spin alignment of vector mesons is independent of it. They exhibit very different energy dependences. We use the longitudinal polarization of the Lambda hyperon and the spin alignment of K* as representative examples to present numerical results of energy dependences and demonstrate such distinct differences. We present the results at the leading twist with perturbative QCD evolutions of fragmentation functions at the leading order.

  5. 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

  6. Energy dependence of resonance production in relativistic heavy ion collisions

    NASA Astrophysics Data System (ADS)

    Shao, Feng-Lan; Song, Jun; Wang, Rui-Qin; Zhang, Mao-Sheng

    2017-01-01

    The production of the hadronic resonances K*0(892), ϕ(1020), Σ*(1385), and Ξ*(1530) in central AA collisions at , 200, and 2760 GeV is systematically studied. The direct production of these resonances at system hadronization is described by the quark combination model and the effects of hadron multiple-scattering stage are dealt with by a ultra-relativistic quantum molecular dynamics model (UrQMD). We study the contribution of these two production sources to final observation and compare the final spectra with the available experimental data. The p T spectra of K*0(892) calculated directly by quark combination model are explicitly higher than the data at low p T ≲ 1.5 GeV, and taking into account the modification of rescattering effects, the resulting final spectra well agree with the data at all three collision energies. The rescattering effect on ϕ(1020) production is weak and including it can slightly improve our description at low p T on the basis of overall agreement with the data. We also predict the p T spectra of Σ*(1385) and Ξ*(1530), to be tested by the future experimental data. Supported by National Natural Science Foundation of China (11575100, 11305076, 11505104)

  7. 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.

  8. New Observations of Europa's Surface Composition: Discovery of an Anti-Jovian Salty Region

    NASA Astrophysics Data System (ADS)

    Fischer, Patrick D.; Brown, Michael E.; Hand, Kevin P.

    2014-11-01

    The surface composition of Europa is the best means available to probe its global chemical cycle and constrain the composition of its ocean. New observations of Europa's near-infrared reflectance spectra were obtained with the OSIRIS instrument on the Keck II telescope. Previous investigations of Europa's surface composition have mostly relied on Galileo NIMS infrared spectra; though NIMS measurements have high spatial resolution, they lack spectral resolution and span a limited spatial extent. Conversely, our observations comprise a near-global spectral map of Europa in the infrared H and K bands. At ~ 1 nm spectral resolution and ~ 100 km spatial resolution, these data reveal global distributions of key spectral features, enabling a more complete characterization of Europa's surface composition than previously possible. Simple linear spectral modelling of these data reproduces the global abundance distributions of water ice and sulfuric acid hydrate. In addition, this modelling reveals a suggestively "salty" region on Europa's anti-Jovian hemisphere. This region is spectrally distinct from both the trailing hemisphere bullseye and the spectrum of pure water ice, and shows a direct spatial correlation to an anti-Jovian chaos unit. Similar chaos regions show enhancements of saltier spectra as well, though to a lesser degree. We report three spectral end member regions on Europa's surface, represented by the trailing hemisphere bullseye, the leading hemisphere north polar "icy" region, and the anti-Jovian "salty" chaos unit. We present global compositional maps, and discuss the potential compositions of the three end member regions.

  9. Using Near Infrared Observations and Models to Analyze Surface Compositions of Kuiper Belt Objects

    NASA Astrophysics Data System (ADS)

    McGuire, Ryan

    Kuiper Belt Objects (KBOs) are primordial icy objects in the outer solar system. Compositional information for KBOs helps us understand the original environment of the solar system as well as identify objects that are compositionally anomalous. Due to the faint nature of KBOs, very few spectroscopic observations have been made of them. Instead, photometric observations at infrared wavelengths are made to partially construct their spectra. I calculate near infrared reflectances for 12 objects using photometric observations from the Gemini North telescope. I combine these near infrared reflectances with data from the Spitzer Space Telescope. This combination of Gemini and Spitzer photometry along with compositional model analysis allows us to find the surface composition (organics, H2O, CO2, CH4, and other hydrated silicates) for these 12 objects. I found that my objects fit into one of four taxonomic classes found in the Kuiper Belt. We have found using the color analysis, that Haumea has water on its surface and Eris is most likely to have methane on its surface. By analyzing this data we measure the compositional mixing in the outer solar system.

  10. Energy dependence of pion and kaon production in central Pb+Pb collisions

    NASA Astrophysics Data System (ADS)

    Afanasiev, S. V.; Anticic, T.; Barna, D.; Bartke, J.; Barton, R. A.; Behler, M.; Betev, L.; Białkowska, H.; Billmeier, A.; Blume, C.; Blyth, C. O.; Boimska, B.; Botje, M.; Bracinik, J.; Bramm, R.; Brun, R.; Bunčić, P.; Cerny, V.; Cramer, J. G.; Csató, P.; Dinkelaker, P.; Eckhardt, V.; Filip, P.; Fodor, Z.; Foka, P.; Freund, P.; Friese, V.; Gál, J.; Gaździcki, M.; Georgopoulos, G.; Gładysz, E.; Hegyi, S.; Höhne, C.; Igo, G.; Jones, P. G.; Kadija, K.; Karev, A.; Kolesnikov, V. I.; Kollegger, T.; Kowalski, M.; Kraus, I.; Kreps, M.; van Leeuwen, M.; Lévai, P.; Malakhov, A. I.; Margetis, S.; Markert, C.; Mayes, B. W.; Melkumov, G. L.; Mischke, A.; Molnár, J.; Nelson, J. M.; Pálla, G.; Panagiotou, A. D.; Perl, K.; Petridis, A.; Pikna, M.; Pinsky, L.; Pühlhofer, F.; Reid, J. G.; Renfordt, R.; Retyk, W.; Roland, C.; Roland, G.; Rybicki, A.; Sammer, T.; Sandoval, A.; Sann, H.; Schmitz, N.; Seyboth, P.; Siklér, F.; Sitar, B.; Skrzypczak, E.; Squier, G. T.; Stock, R.; Ströbele, H.; Susa, T.; Szentpétery, I.; Sziklai, J.; Trainor, T. A.; Varga, D.; Vassiliou, M.; Veres, G. I.; Vesztergombi, G.; Vranić, D.; Wetzler, A.; Whitten, C.; Yoo, I. K.; Zaranek, J.; Zimányi, J.

    2002-11-01

    Measurements of charged pion and kaon production in central Pb+Pb collisions at 40, 80, and 158 A GeV are presented. These are compared with data at lower and higher energies as well as with results from p+p interactions. The mean pion multiplicity per wounded nucleon increases approximately linearly with s1/4NN with a change of slope starting in the region 15-40 A GeV. The change from pion suppression with respect to p+p interactions, as observed at low collision energies, to pion enhancement at high energies occurs at about 40A GeV. A nonmonotonic energy dependence of the ratio of K+ to π+ yields is observed, with a maximum close to 40A GeV and an indication of a nearly constant value at higher energies. The measured dependences may be related to an increase of the entropy production and a decrease of the strangeness to entropy ratio in central Pb+Pb collisions in the low SPS energy range, which is consistent with the hypothesis that a transient state of deconfined matter is created above these energies. Other interpretations of the data are also discussed.

  11. Energy-dependent expansion of .177 caliber hollow-point air gun projectiles.

    PubMed

    Werner, Ronald; Schultz, Benno; Bockholdt, Britta; Ekkernkamp, Axel; Frank, Matthias

    2017-05-01

    Amongst hundreds of different projectiles for air guns available on the market, hollow-point air gun pellets are of special interest. These pellets are characterized by a tip or a hollowed-out shape in their tip which, when fired, makes the projectiles expand to an increased diameter upon entering the target medium. This results in an increase in release of energy which, in turn, has the potential to cause more serious injuries than non-hollow-point projectiles. To the best of the authors' knowledge, reliable data on the terminal ballistic features of hollow-point air gun projectiles compared to standard diabolo pellets have not yet been published in the forensic literature. The terminal ballistic performance (energy-dependent expansion and penetration) of four different types of .177 caliber hollow-point pellets discharged at kinetic energy levels from approximately 3 J up to 30 J into water, ordnance gelatin, and ordnance gelatin covered with natural chamois as a skin simulant was the subject of this investigation. Energy-dependent expansion of the tested hollow-point pellets was observed after being shot into all investigated target media. While some hollow-point pellets require a minimum kinetic energy of approximately 10 J for sufficient expansion, there are also hollow-point pellets which expand at kinetic energy levels of less than 5 J. The ratio of expansion (RE, calculated by the cross-sectional area (A) after impact divided by the cross-sectional area (A 0) of the undeformed pellet) of hollow-point air gun pellets reached values up of to 2.2. The extent of expansion relates to the kinetic energy of the projectile with a peak for pellet expansion at the 15 to 20 J range. To conclude, this work demonstrates that the hollow-point principle, i.e., the design-related enlargement of the projectiles' frontal area upon impact into a medium, does work in air guns as claimed by the manufacturers.

  12. ENERGY DEPENDENCE OF SYNCHROTRON X-RAY RIMS IN TYCHO’S SUPERNOVA REMNANT

    SciTech Connect

    Tran, Aaron; Williams, Brian J.; Petre, Robert; Reynolds, Stephen P.

    2015-10-20

    Several young supernova remnants (SNRs) exhibit thin X-ray bright rims of synchrotron radiation at their forward shocks. Thin rims require strong magnetic field amplification beyond simple shock compression if rim widths are only limited by electron energy losses. But, magnetic field damping behind the shock could produce similarly thin rims with less extreme field amplification. Variation of rim width with energy may thus discriminate between competing influences on rim widths. We measured rim widths around Tycho's SNR in five energy bands using an archival 750 ks Chandra observation. Rims narrow with increasing energy and are well described by either loss-limited or damped scenarios, so X-ray rim width-energy dependence does not uniquely specify a model. But, radio counterparts to thin rims are not loss-limited and better reflect magnetic field structure. Joint radio and X-ray modeling favors magnetic damping in Tycho's SNR with damping lengths ∼1%–5% of remnant radius and magnetic field strengths ∼50–400 μG assuming Bohm diffusion. X-ray rim widths are ∼1% of remnant radius, somewhat smaller than inferred damping lengths. Electron energy losses are important in all models of X-ray rims, suggesting that the distinction between loss-limited and damped models is blurred in soft X-rays. All loss-limited and damping models require magnetic fields ≳20 μG, affirming the necessity of magnetic field amplification beyond simple compression.

  13. Energy-dependent relaxation time in quaternary amorphous oxide semiconductors probed by gated Hall effect measurements

    NASA Astrophysics Data System (ADS)

    Socratous, Josephine; Watanabe, Shun; Banger, Kulbinder K.; Warwick, Christopher N.; Branquinho, Rita; Barquinha, Pedro; Martins, Rodrigo; Fortunato, Elvira; Sirringhaus, Henning

    2017-01-01

    Despite the success of exploiting the properties of amorphous oxide semiconductors for device applications, the charge transport in these materials is still not clearly understood. The observation of a definite Hall voltage suggests that electron transport in the conduction band is free-electron-like. However, the temperature dependence of the Hall and field-effect mobilities cannot be explained using a simple bandlike model. Here, we perform gated Hall effect measurements in field-effect transistors, which allow us to make two independent estimates of the charge carrier concentration and determine the Hall factor providing information on the energy dependence of the relaxation time. We demonstrate that the Hall factor in a range of sputtered and solution-processed quaternary amorphous oxides, such as a-InGaZnO, is close to two, while in ternary oxides, such as InZnO, it is near unity. This suggests that quaternary elements like Ga act as strong ionized impurity scattering centers in these materials.

  14. Energy Dependence of Synchrotron X-Ray Rims in Tycho's Supernova Remnant

    NASA Technical Reports Server (NTRS)

    Tran, Aaron; Williams, Brian J.; Petre, Robert; Ressler, Sean M.; Reynolds, Stephen P.

    2015-01-01

    Several young supernova remnants exhibit thin X-ray bright rims of synchrotron radiation at their forward shocks. Thin rims require strong magnetic field amplification beyond simple shock compression if rim widths are only limited by electron energy losses. But, magnetic field damping behind the shock could produce similarly thin rims with less extreme field amplification. Variation of rim width with energy may thus discriminate between competing influences on rim widths. We measured rim widths around Tycho's supernova remnant in 5 energy bands using an archival 750 ks Chandra observation. Rims narrow with increasing energy and are well described by either loss-limited or damped scenarios, so X-ray rim width-energy dependence does not uniquely specify a model. But, radio counterparts to thin rims are not loss-limited and better reflect magnetic field structure. Joint radio and X-ray modeling favors magnetic damping in Tycho's SNR with damping lengths approximately 1-5% of remnant radius and magnetic field strengths approximately 50-400 micron G assuming Bohm diffusion. X-ray rim widths are approximately 1% of remnant radius, somewhat smaller than inferred damping lengths. Electron energy losses are important in all models of X-ray rims, suggesting that the distinction between loss-limited and damped models is blurred in soft X-rays. All loss-limited and damping models require magnetic fields approximately greater than 20 micron G, arming the necessity of magnetic field amplification beyond simple compression.

  15. 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.

  16. 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.

  17. In situ observation of mechanical damage within a SiC-SiC ceramic matrix composite

    NASA Astrophysics Data System (ADS)

    Saucedo-Mora, L.; Lowe, T.; Zhao, S.; Lee, P. D.; Mummery, P. M.; Marrow, T. J.

    2016-12-01

    SiC-SiC ceramic matrix composites are candidate materials for fuel cladding in Generation IV nuclear fission reactors and as accident tolerant fuel clad in current generation plant. Experimental methods are needed that can detect and quantify the development of mechanical damage, to support modelling and qualification tests for these critical components. In situ observations of damage development have been obtained of tensile and C-ring mechanical test specimens of a braided nuclear grade SiC-SiC ceramic composite tube, using a combination of ex situ and in situ computed X-ray tomography observation and digital volume correlation analysis. The gradual development of damage by matrix cracking and also the influence of non-uniform loading are examined.

  18. 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.

  19. 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.

  20. ROSAT Observations of the Composite Supernova Remnant G326.3-1.8

    DTIC Science & Technology

    1993-12-20

    We have observed X-ray emission from the radio-defined composite (shell plus filled-center plerion) Galactic supernova remnant ( SNR ) 0326.3 - 1.8...radio studies that would place the SNR significantly further than this lower limit. Higher quality radio absorption measurements are warranted to confirm...our distance determination. This result, along with other recent ROSAT studies of SNRs , implies that improved distance estimates may be established

  1. EPR dosimetry of cortical bone and tooth enamel irradiated with X and gamma rays: Study of energy dependence

    SciTech Connect

    Schauer, D.A.; Links, J.M. ); Desrosiers, M.F.; Le, F.G.; Seltzer, S.M. )

    1994-04-01

    Previous investigators have reported that the radiation-induced EPR signal intensity in compact or cortical bone increases up to a factor of two with decreasing photon energy for a given absorbed dose. If the EPR signal intensity was dependent on energy, it could limit the application of EPR spectrometry and the additive reirradiation method to obtain dose estimates. We have recently shown that errors in the assumptions governing conversion of measured exposure to absorbed dose can lead to similar [open quotes]apparent[close quotes] energy-dependence results. We hypothesized that these previous results were due to errors in the estimated dose in bone, rather than the effects of energy dependence per se. To test this hypothesis we studied human adult cortical bone from male and female donors ranging in age from 23 to 95 years, and bovine tooth enamel, using 34 and 138 keV average energy X-ray beams and [sup 137]Cs (662 keV) and [sup 60]Co (1250 keV) [gamma] rays. In a femur from a 47-year-old male (subject 1), there was a difference of borderline significance at the [alpha] = 0.05 level in the mean radiation-induced hydroxyapatite signal intensities as a function of photon energy. No other statistically significant differences in EPR signal intensity as a function of photon energy were observed in this subject, or in the tibia from a 23-year-old male (subject 2) and the femur from a 75-year-old female (subject 3). However, there was a trend toward a decrease (12-15%) in signal intensity at the lowest energy compared with the highest energy in subjects 1 and 3. Further analysis of the data from subject 1 revealed that this trend, which is in the opposite direction of previous reports but is consistent with theory, is statistically significant. There were no efforts of energy dependence in the tooth samples. 16 refs., 7 figs., 5 tabs.

  2. 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.

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

    NASA Astrophysics Data System (ADS)

    Olszówka-Myalska, Anita

    2016-08-01

    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.

  4. Hanle precession in the presence of energy-dependent coupling between localized states and an epitaxial graphene spin channel

    NASA Astrophysics Data System (ADS)

    van den Berg, J. J.; Kaverzin, A.; van Wees, B. J.

    2016-12-01

    Hanle spin precession measurements are a common method to extract the spin transport properties of graphene. In epitaxial graphene on silicon carbide, these measurements show unexpected behavior, due to presumed localized states in the carbon buffer layer that is present between the channel and the substrate. As a consequence, the Hanle curve narrows in its magnetic field dependence and can show an unconventional shape, which has been experimentally observed and modeled in previous studies. Here, we extend the previously developed model by assuming that the localized states are charge traps, that have a power-law distribution of trapping times. Our simulations show that the energy dependence of these trapping times can be extracted from the temperature evolution of the Hanle curve, which was previously observed in experiments. Our extended model gives better insight into what processes play a role when a spin channel is coupled to localized states and their relation to the experimental observations.

  5. Gamma-rigid regime of the Bohr-Mottelson Hamiltonian in energy-dependent approach

    NASA Astrophysics Data System (ADS)

    Alimohammadi, M.; Hassanabadi, H.

    2016-10-01

    We determine the energy spectrum and wave function for the Bohr-Mottelson Hamiltonian on γ-rigid regime separately with the harmonic and Coulomb energy-dependent potentials. We study the effect of potential parameters on the energy levels and probability density distribution. The transition rates are determined in each case.

  6. 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

  7. The Compton Microscope: Using the Energy Dependence of QPO Amplitudes to Probe Their Origin in Accretion Disks

    NASA Astrophysics Data System (ADS)

    Lehr, D. E.; Wagoner, R. V.; Wilms, J.

    1999-12-01

    We report the development of a new tool to determine the origin of quasi-periodic oscillations (QPOs) in accretion disk systems. The technique uses the source energy spectrum and the energy dependence of the QPO fractional amplitude to restrict the location of the emission region of the modulated photons, which are assumed to originate in the inner accretion disk. Both Monte-Carlo and semi-analytical methods are presented. We assume the accretion disk is enshrouded by a slab atmosphere of hot electrons in which unsaturated Compton scattering produces the high-energy spectrum. Properties of the atmosphere, in particular the electron temperature, are assumed functions of radius from the central compact object. We show that our model reproduces the observed energy dependence of the fractional amplitude of the 67 Hz QPO in GRS 1915+105 if the QPO is assumed to originate at a particular region of the inner disk. This work was supported by NASA Graduate Student Researchers Program grant NGT 5-50044 to D.E.L., NASA grant NAG 5-3102 to R.V.W., and grant number Sta 173/22 of the Deutsche Forschungsgemeinschaft to J.W. This research has made use of data obtained through the High Energy Astrophysics Science Archive Research Center Online Service, provided by the NASA/Goddard Space Flight Center.

  8. Energy dependence and temporal evolution of the He-3/He-4 ratios in heavy-ion-rich energetic particle events

    NASA Technical Reports Server (NTRS)

    Moebius, E.; Hovestadt, D.; Klecker, B.; Gloeckler, G.

    1980-01-01

    A study is presented of the energy dependence of the He-3/He-4 between 0.44 and 4.1 MeV per nucleon for six heavy-ion-rich events observed in 1974 and 1976. The observations were made using the low-energy dE/dx vs E Ultralow-Energy Particle telescope on IMP 8. It was found that all selected heavy-ion-rich events are also enriched in He-3: that the He-3/He-4 ratio decreases with decreasing energies; and that a rapid temporal evolution of the He-3/He-4 and the Fe/(H + He) ratios is strongly correlated during one event with the maximum value at the onset. These results are analyzed in terms of a model based on the preferential injection of He-3 and Fe resulting from turbulent ion heating and subsequent Fermi acceleration.

  9. 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

  10. C_60/Ferromagnet Composites: Observation of a Temperature-Dependent Crossover from Negative to Positive Magnetoresistance

    NASA Astrophysics Data System (ADS)

    Hudspeth, Q. M.; Arnason, S. B.; Hebard, A. F.

    2001-03-01

    In this work we report on the fabrication and characterization of composite thin films (M_xC_60) of C_60 with ferromagnetic metals (M). Magnetoresistance (MR) measurements will be presented for Ni_xC_60 samples with x in the range 20 - 90. A change in MR from negative (characteristic of pure Ni) at high temperatures to positive at low temperatures is observed as the sample temperature is decreased from 300 to 2 K. This crossover from negative to positive MR is similar to that seen below 1 K in phosphorous-doped silicon[1], and more recently at higher temperatures in Fe_1-yCo_ySi[2] and is attributed to quantum interference effects in the presence of Coulomb interactions with spin splitting. This interpretation can be tested for the M_xC_60 composites by comparing the MR of M_xC_60 (M= Fe, Co, Ni) with Gd_xC_60. In the Gd composite we would expect the positive MR to be absent since magnetism in Gd arises from local moments and the carriers are no longer responsible for both magnetism and conduction as they are in Fe_1-yCo_ySi. [1] T. F. Rosenbaum et al., Phys. Rev. Lett. 47, 1758 (1981). [2] N. Manyala, et al., Nature 404, 581 (2000).

  11. Ionosphere of venus: first observations of the dayside ion composition near dawn and dusk.

    PubMed

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

    1979-02-23

    The first in situ measurements of the composition of the ionosphere of Venus are provided by independent Bennett radio-frequency ion mass spectrometers on the Pioneer Venus bits and orbiter spacecraft, exploring the dawn and duskside regions, respectively. An extensive composition of ion species, rich in oxygen, nitrogen, and carbon chemistry is idenitified. The dominant topside ion is O(+), with C(+), N(+), H(+), and He(+) as prominent secondary ions. In the lower ionosphere, the ionzization peak or F(1) layer near 150 kilometers reaches a concentration of about 5 x l0(3) ions per cubic centimeter, and is composed of the dominant molecular ion, O(2)(+), with NO(+), CO(+), and CO(2)(+), constituting less than 10 percent of the total. Below the O(+) peak near 200 kilometers, the ions exhibit scale heights consistent with a neutral gas temperature of about 180 K near the terminator. In the upper ionosphere, scale heights of all species reflect the effects of plasma transport, which lifts the composition upward to the often abrupt ionopause, or thermal ion boundary, which is observed to vary in height between 250 to 1800 kilometers, in response to solar wind dynamics.

  12. Deep Chandra Observations of the Composite Supernova Remnant G327.1-1.1

    NASA Astrophysics Data System (ADS)

    Temim, Tea

    2014-11-01

    G327.1-1.1 is a composite SNR containing a symmetric radio shell and a PWN that has likely been disrupted by the reverse shock. Previous X-ray studies reveled a complex morphology; a compact core embedded in bow-shock-like structure, prong-like features extending into large arcs, and thermal emission from the SNR shell. We present deep, 350 ks Chandra observations of G327.1-1.1 that provide new information about the properties of the system, such as the spatial variations in the spectral index across the observed PWN structures, and the thermal temperature across the SNR shell. We also present preliminary HD simulations of an asymmetric PWN/SNR interaction in a system with a moving pulsar, expanding into a non-uniform ISM density, which offer new insight into the nature of the remnant.

  13. 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++, 06+, 07+, 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.

  14. 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.

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

    PubMed

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

    1979-02-23

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

  16. 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

  17. 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.

  18. 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.

    2016-11-01

    LS 5039 is so far the best-studied γ-ray binary system at multiwavelength 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 International Gamma-Ray Astrophysics Laboratory (INTEGRAL)/INTEGRAL on-board Imager/INTEGRAL Soft Gamma-Ray Imager 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-Large Area Telescope (LAT) data between 30 MeV and 10 GeV in five 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 anticlockwise 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 0.45-0.9) and from the superior conjunction phase region (orbital phase 0.9-0.45) 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.

  19. Corrections to charge exchange spectroscopic measurements in TFTR due to energy-dependent excitation rates

    SciTech Connect

    Howell, R.B.; Fonck, R.J.; Knize, R.J.; Jaehnig, K.P.

    1988-08-01

    The use of charge exchange spectrocopy to determine plasma rotation speeds and ion temperature is complicated by the energy dependence of the excitation cross sections. The Doppler-broadened spectral line shape is distorted by the relative velocity between the neutral hydrogen atoms of the injected beam and impurity ions. The asymmetric nature of the energy dependence of this cross section causes a non-motional shift of the line center and a non-thermal change in the line width. These effects vary with the angles between the beam direction, rotation velocity direction, and direction of the viewing sightline. When viewing two neutral beams at different angles on TFTR, the two measurements of v/sub phi/(r) show discrepancies about 20 to 30% with each other. The calculation of the spectral intensity profiles, using the excitation rates available, overcorrects these discrepancies and indicates the need for better excitation coefficients. 10 refs., 5 figs.

  20. Circumstellar Dust Composition of M-type Mira Variables observed with phase with Spitzer

    NASA Astrophysics Data System (ADS)

    Güth, Tina; Creech-Eakman, Michelle J.

    2017-01-01

    Our research concerns the detailed dust composition surrounding Mira variables. These regular pulsators are easily observed in the optical and infrared due to their changes in brightness. Data on 25 galactic Miras were obtained with the Spitzer Infrared Spectrograph (IRS) instrument in 2008-09 under a GO program led by Creech-Eakman. The stars were observed approximately once per month to track changes in their brightness and spectral features. This dataset is unique for both the number of observations of each star and the high SNR due to their intrinsic brightness.The stars in this study span the range of oxygen- to carbon-rich, with each type exhibiting certain known solid state components (i.e dust). The current focus is on trying to reproduce dust spectral features in the short, high (SH) and long, high (LH) resolution wavelength range (~9.7 - 40 microns) of the oxygen-rich Miras (C/O < 1). These high resolution, reduced spectra reveal a wonderful “forest” of features that provide insight into the stellar atmospheres and circumstellar dust composition with phase.Using the 1-D radiative transfer modeling code, DUSTY, we are attempting to identify several broad, and some sharp, dust features by including recently derived laboratory spectral indices for dust opacities. Prominent features seen in oxygen-rich Mira variables include potential identifications of water ice emission, as well as amorphous and crystalline silicates. We implement a greybody continuum obtained from MARCS, a 1-D hydrostatic spherical LTE model grid code, as the stellar continuum input for DUSTY. Using a greybody rather than a blackbody curve allows us to obtain a better agreement between the DUSTY spectrum and the Spitzer data. We will show these amended model fits that will improve the identification of the dust and other features in the spectra.

  1. 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.

  2. 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

    2007-12-07

    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.

  3. 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.

  4. 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.

  5. Energy dependent 3-body loss in out-of-equilibrium 1D Bose gases

    NASA Astrophysics Data System (ADS)

    Zundel, Laura; Xia, Lin; Wilson, Joshua; Riou, Jean-Felix; Weiss, David

    2015-05-01

    We measure the three-body loss of out-of-equilibrium one-dimensional (1D) Bose gases and find that it depends strongly on the average energy of the distribution. The theory of three-body loss in 1D gas experiments is incomplete due to the challenge of calculating how correlations evolve. We present an empirical model based on energy dependent correlations and show that it reproduces the data.

  6. 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.

  7. 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.

  8. 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 scanner 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

  9. 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

    2016-01-08

    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

  10. Satellite Observations of Arctic and Antarctic Polar Stratospheric Clouds and Atmospheric Composition

    NASA Astrophysics Data System (ADS)

    Lambert, A.; Santee, M. L.; Wu, D. L.

    2012-12-01

    We present an overview of polar stratospheric clouds (PSCs) and atmospheric composition during the 2008-2012 Arctic and Antarctic seasons using A-Train measurements of lidar backscatter and gas phase concentrations of HNO3, H2O, HCl and ClO. The processes of denitrification, dehydration and chlorine activation are investigated. PSC types are classified using the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite which measures vertical profiles of aerosol and cloud backscatter at 532 nm (total and perpendicular polarization) and 1064 nm. Ambient temperature/pressure profiles and constituent gases are obtained from the Aura Microwave Limb Sounder (MLS). Since April 2008 these two instruments have flown in close formation in the A-Train, maintaining colocation across track to less than 10 km and with temporal sampling differences less than 30 seconds.

  11. Impact of Deep Convection on UTLS Composition -New Observations from Recent Airborne Field Studies

    NASA Astrophysics Data System (ADS)

    Pan, L.

    2014-12-01

    Deep convection redistributes chemical trace gas species throughout the troposphere. Tropopause-penetrating deep convection injects water vapor and pollutants into the lower stratosphere. To obtain the necessary information for characterizing its role in chemistry-climate coupling, the impact of deep convection on UTLS ozone, water vapor, and short-lived organic species has been a key component of several recent airborne field campaigns. We present selected findings and observational highlights from two airborne field campaigns. They are the CONvective TRansport of Active Species in the Tropics (CONTRAST) experiment, conducted January-February 2014 over the western Pacific using the NCAR GV research aircraft, in collaboration with the UK FAAM BAe146 and the NASA Global Hawk, and the Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) experiment, conducted August-September 2013 over the north America using the NASA DC-8 and ER-2 research aircraft.

  12. 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.

  13. Recent laboratory and field observations of the chemical composition of atmospheric nanoparticles

    NASA Astrophysics Data System (ADS)

    Smith, J. N.; Winkler, P.; Hildebrandt Ruiz, L.; Lawler, M. J.; Ortega, J.; Fry, J.; Barsanti, K. C.; McMurry, P. H.; Johnston, M. V.

    2012-12-01

    This presentation will focus on understanding the species and mechanisms that are responsible for the formation and growth of atmospheric nanoparticles. We report 10 - 40 nm diameter nanoparticle chemical composition measurements performed in two coastal sites (Mace Head, Ireland, and Lewes, Delaware USA) and two forested sites (Hyytiälä, Finland, and Manitou Forest, Colorado USA) with the recently-developed High Resolution Time-of-Flight Thermal Desorption Chemical Ionization Mass Spectrometer (HTOF-TDCIMS). These field measurements are supplemented by laboratory experiments of particle formation and growth performed at NCAR using a flow tube apparatus and a Teflon bag reaction chamber, and by thermodynamic modeling. Together, our field and laboratory observations point to crucial roles played in nanoparticle growth by two compounds: organic acids and organonitrates. The first, organic acids, are major contributors to the organic fraction in sub-20 nm diameter biogenic nanoparticles but appear to be less abundant in the organic fraction of larger particles, the latter of which are dominated by multifunctional carbonyl- and alcohol-containing compounds. The observed changes in chemical composition of the organic fraction as a function of particle size are supported by thermodynamic modeling results. The second, organonitrates, are commonly found in ambient nanoparticles as small as 10 nm in diameter. However unlike organic acids, organonitrates become increasingly more important in nanoparticle growth as particle size increases. Laboratory experiments suggest that organonitrates formed from the nitrate radical oxidation of biogenic organic compounds, a subset of total organonitrates, exhibit particularly low volatility and can thus partition into the smallest nanoparticles. This is confirmed by HTOF-TDCIMS measurements of 10 - 20 nm diameter particles, which show that particulate phase organonitrates peak in the morning, shortly following the period where

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

    PubMed

    Erol, Ayse; Akalin, Elif; Sarcan, Fahrettin; Donmez, Omer; Akyuz, Sevim; Arikan, Cetin M; Puustinen, Janne; Guina, Mircea

    2012-11-28

    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.

  15. 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.

  16. 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.

  17. Observations of the ring current composition at L less than 4

    NASA Astrophysics Data System (ADS)

    Lundin, R.; Lyons, L. R.; Pisarenko, N.

    1980-06-01

    Observations showing that the low energy (less than 17 keV) portion of the ring current at L less than 4 is composed mainly of O(+) and He(+) ions during quiet times and the recovery of magnetic storms are presented. The data were obtained from the ion composition experiment on board the Prognoz-7 satellite during several passes through the ring current region. For L less than 3.5, the relative abundance of H(+) was only a few percent of the ion energy density in the energy range of 0.2-17 keV. Although O(+) normally dominates for L less than 4, the relative contribution of He(+) increases with decreasing L, and in one case became more abundant than O(+) for L less than 3. One example of a storm injection shows dominance by O(+) ions (82%) with H(+) only giving a minor contribution (15%) to the density. These observations are consistent with inferences based on charge exchange, H(+) being most rapidly lost and He(+) being the most stable.

  18. Particle sizes and composition of Mars atmospheric dust based upon Viking and Mariner 9 observations

    NASA Technical Reports Server (NTRS)

    Clancy, R. T.; Lee, S. W.; Gladstone, G. R.

    1993-01-01

    Mars atmospheric dust can play an important role in the thermal structure of the Mars atmosphere during periods of high dust loading. However, the radiative properties of Mars atmospheric dust remain uncertain due to uncertain definitions of the dust composition and size distribution. The analysis by Toon et al., of Mariner 9 IRIS spectra during the 1971-1972 global dust storm indicated a reasonable match between the modeled 9-micron absorption of montmorillinite and the observed 9-micron absorption. Toon et al. also determined that an effective (cross-section weighted) mean radius of 2.5 microns (R(sub mode) = 0.4 microns) provided a consistent fit of montmorillinite to the IRIS dust spectra at 9 microns. Pollack et al. analyzed Viking lander observations of atmospheric extinction and scattering at visible-near IR wavelengths (0.5-1.0 microns), and obtained consistency with the Toon et al. dust size distribution when the effects of nonspherical particle shapes were included. An additional, minor (1 percent) component of visible-ultraviolet absorbing material was required to model the derived visible (0.86) and ultraviolet (0.4-0.6) single-scattering albedos of the dust, since montmorillinite does not absorb sufficiently in this wavelength region. A combined analysis of the Viking IRTM and Mariner 9 observations was conducted to reassess the model of Mars atmospheric ultraviolet-to-infrared measurements of dust absorption and scattering. The optical constants for palagonite are incorporated in a doubling-adding radiative transfer model of the Mars atmosphere to simulate Mariner 9 IRIS spectra as well as the Viking IRTM IR band observations. Visible and ultraviolet single-scattering albedos based on the Hansen and Travis Mie scattering code were also derived. A tentative conclusion is that smaller dust particles (R(sub mode) = 0.15 microns, cross-section weighted mean R = 1.2 microns) composed of palagonite provide a much improved fit to the Mariner 9 IRIS spectra

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. Simulations and observations of plasma depletion, ion composition, and airglow emissions in two auroral ionospheric depletion experiments

    NASA Technical Reports Server (NTRS)

    Yau, A. W.; Whalen, B. A.; Harris, F. R.; Gattinger, R. L.; Pongratz, M. B.

    1985-01-01

    Observations of plasma depletion, ion composition modification, and airglow emissions in the Waterhole experiments are presented. The detailed ion chemistry and airglow emission processes related to the ionospheric hole formation in the experiment are examined, and observations are compared with computer simulation results. The latter indicate that the overall depletion rates in different parts of the depletion region are governed by different parameters.

  5. The energy dependence of the diffraction minimum in the elastic scattering and new LHC data

    NASA Astrophysics Data System (ADS)

    Selyugin, O. V.

    2017-03-01

    The soft diffraction phenomena in the elastic proton-proton scattering are reviewed from the viewpoint of experiments at the LHC (TOTEM and ATLAS collaboration). In the framework of the High Energy Generalized Structure (HEGS) model the form of the diffraction minimum in the nucleon-nucleon elastic scattering in a wide energy region is analyzed. The energy dependencies of the main characteristics of the diffraction dip are obtained. The numerical predictions at LHC energies are presented. The comparison of the model predictions with the new LHC data at √{ s} = 13 TeV is made.

  6. 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.

  7. Energy dependence of photoion rotational distributions of N2 and CO

    NASA Astrophysics Data System (ADS)

    Choi, Heung Cheun; Rao, R. M.; Mihill, A. G.; Kakar, Sandeep; Poliakoff, E. D.; Wang, Kwanghsi; McKoy, V.

    1994-01-01

    We present the first measurements of rotational distributions for photoionization over extended energy ranges [0<=Ek<=200 eV for N2 (2σ-1u) and of 3<=Ek<=125 eV for CO (4σ-1)]. The N2 and CO results show a strikingly unusual and different energy dependence. Although differences are expected due to the absence of a center of symmetry in CO, detailed calculations reveal that this behavior arises from the presence of Cooper minima in the photoelectron continuum (kσg) in the case of N2 and from an f-wave shape resonance for 4σ-1 photoionization in CO.

  8. 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.

  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. Measurement of the energy dependence of the total photon-proton cross section at HERA

    NASA Astrophysics Data System (ADS)

    ZEUS Collaboration; Abramowicz, H.; Abt, I.; Adamczyk, L.; Adamus, M.; Aggarwal, R.; Antonelli, S.; Antonioli, P.; Antonov, A.; Arneodo, M.; Aushev, V.; Aushev, Y.; Bachynska, O.; Bamberger, A.; Barakbaev, A. N.; Barbagli, G.; Bari, G.; Barreiro, F.; Bartsch, D.; Basile, M.; Behnke, O.; Behr, J.; Behrens, U.; Bellagamba, L.; Bertolin, A.; Bhadra, S.; Bindi, M.; Blohm, C.; Bokhonov, V.; Bołd, T.; Boos, E. G.; Borras, K.; Boscherini, D.; Bot, D.; Boutle, S. K.; Brock, I.; Brownson, E.; Brugnera, R.; Brümmer, N.; Bruni, A.; Bruni, G.; Brzozowska, B.; Bussey, P. J.; Butterworth, J. M.; Bylsma, B.; Caldwell, A.; Capua, M.; Carlin, R.; Catterall, C. D.; Chekanov, S.; Chwastowski, J.; Ciborowski, J.; Ciesielski, R.; Cifarelli, L.; Cindolo, F.; Contin, A.; Cooper-Sarkar, A. M.; Coppola, N.; Corradi, M.; Corriveau, F.; Costa, M.; D'Agostini, G.; Dal Corso, F.; Del Peso, J.; Dementiev, R. K.; de Pasquale, S.; Derrick, M.; Devenish, R. C. E.; Dobur, D.; Dolgoshein, B. A.; Dolinska, G.; Doyle, A. T.; Drugakov, V.; Durkin, L. S.; Dusini, S.; Eisenberg, Y.; Ermolov, P. F.; Eskreys, A.; Fang, S.; Fazio, S.; Ferrando, J.; Ferrero, M. I.; Figiel, J.; Forrest, M.; Foster, B.; Fourletov, S.; Gach, G.; Galas, A.; Gallo, E.; Garfagnini, A.; Geiser, A.; Gialas, I.; Gladilin, L. K.; Gladkov, D.; Glasman, C.; Gogota, O.; Golubkov, Yu. A.; Göttlicher, P.; Grabowska-Bołd, I.; Grebenyuk, J.; Gregor, I.; Grigorescu, G.; Grzelak, G.; Gueta, O.; Gwenlan, C.; Haas, T.; Hain, W.; Hamatsu, R.; Hart, J. C.; Hartmann, H.; Hartner, G.; Hilger, E.; Hochman, D.; Hori, R.; Horton, K.; Hüttmann, A.; Iacobucci, G.; Ibrahim, Z. A.; Iga, Y.; Ingbir, R.; Ishitsuka, M.; Jakob, H.-P.; Januschek, F.; Jimenez, M.; Jones, T. W.; Jüngst, M.; Kadenko, I.; Kahle, B.; Kamaluddin, B.; Kananov, S.; Kanno, T.; Karshon, U.; Karstens, F.; Katkov, I. I.; Kaur, M.; Kaur, P.; Keramidas, A.; Khein, L. A.; Kim, J. Y.; Kisielewska, D.; Kitamura, S.; Klanner, R.; Klein, U.; Koffeman, E.; Kooijman, P.; Korol, Ie.; Korzhavina, I. A.; Kotański, A.; Kötz, U.; Kowalski, H.; Kulinski, P.; Kuprash, O.; Kuze, M.; Lee, A.; Levchenko, B. B.; Levy, A.; Libov, V.; Limentani, S.; Ling, T. Y.; Lisovyi, M.; Lobodzinska, E.; Lohmann, W.; Löhr, B.; Lohrmann, E.; Loizides, J. H.; Long, K. R.; Longhin, A.; Lontkovskyi, D.; Lukina, O. Yu.; Łużniak, P.; Maeda, J.; Magill, S.; Makarenko, I.; Malka, J.; Mankel, R.; Margotti, A.; Marini, G.; Martin, J. F.; Mastroberardino, A.; Mattingly, M. C. K.; Melzer-Pellmann, I.-A.; Miglioranzi, S.; Idris, F. Mohamad; Monaco, V.; Montanari, A.; Morris, J. D.; Mujkic, K.; Musgrave, B.; Nagano, K.; Namsoo, T.; Nania, R.; Nicholass, D.; Nigro, A.; Ning, Y.; Noor, U.; Notz, D.; Nowak, R. J.; Nuncio-Quiroz, A. E.; Oh, B. Y.; Okazaki, N.; Oliver, K.; Olkiewicz, K.; Onishchuk, Yu.; Papageorgiu, K.; Parenti, A.; Paul, E.; Pawlak, J. M.; Pawlik, B.; Pelfer, P. G.; Pellegrino, A.; Perlanski, W.; Perrey, H.; Piotrzkowski, K.; Plucinski, P.; Pokrovskiy, N. S.; Polini, A.; Proskuryakov, A. S.; Przybycień, M.; Raval, A.; Reeder, D. D.; Reisert, B.; Ren, Z.; Repond, J.; Ri, Y. D.; Robertson, A.; Roloff, P.; Ron, E.; Rubinsky, I.; Ruspa, M.; Sacchi, R.; Salii, A.; Samson, U.; Sartorelli, G.; Savin, A. A.; Saxon, D. H.; Schioppa, M.; Schlenstedt, S.; Schleper, P.; Schmidke, W. B.; Schneekloth, U.; Schönberg, V.; Schörner-Sadenius, T.; Schwartz, J.; Sciulli, F.; Shcheglova, L. M.; Shehzadi, R.; Shimizu, S.; Singh, I.; Skillicorn, I. O.; Słomiński, W.; Smith, W. H.; Sola, V.; Solano, A.; Son, D.; Sosnovtsev, V.; Spiridonov, A.; Stadie, H.; Stanco, L.; Stern, A.; Stewart, T. P.; Stifutkin, A.; Stopa, P.; Suchkov, S.; Susinno, G.; Suszycki, L.; Sztuk-Dambietz, J.; Szuba, D.; Szuba, J.; Tapper, A. D.; Tassi, E.; Terrón, J.; Theedt, T.; Tiecke, H.; Tokushuku, K.; Tomalak, O.; Tomaszewska, J.; Tsurugai, T.; Turcato, M.; Tymieniecka, T.; Uribe-Estrada, C.; Vázquez, M.; Verbytskyi, A.; Viazlo, O.; Vlasov, N. N.; Volynets, O.; Walczak, R.; Abdullah, W. A. T. Wan; Whitmore, J. J.; Whyte, J.; Wiggers, L.; Wing, M.; Wlasenko, M.; Wolf, G.; Wolfe, H.; Wrona, K.; Yagües-Molina, A. G.; Yamada, S.; Yamazaki, Y.; Yoshida, R.; Youngman, C.; Żarnecki, A. F.; Zawiejski, L.; Zenaiev, O.; Zeuner, W.; Zhautykov, B. O.; Zhmak, N.; Zhou, C.; Zichichi, A.; Zolko, M.; Zotkin, D. S.; Zulkapli, Z.

    2011-03-01

    The energy dependence of the photon-proton total cross section, σtotγp, was determined from e+p scattering data collected with the ZEUS detector at HERA at three values of the center-of-mass energy, W, of the γp system in the range 194

  11. Measurement of the energy dependence of the total photon-proton cross section at HERA

    NASA Astrophysics Data System (ADS)

    Abramowicz, H.; Abt, I.; Adamczyk, L.; Adamus, M.; Aggarwal, R.; Antonelli, S.; Antonioli, P.; Antonov, A.; Arneodo, M.; Aushev, V.; Aushev, Y.; Bachynska, O.; Bamberger, A.; Barakbaev, A. N.; Barbagli, G.; Bari, G.; Barreiro, F.; Bartsch, D.; Basile, M.; Behnke, O.; Behr, J.; Behrens, U.; Bellagamba, L.; Bertolin, A.; Bhadra, S.; Bindi, M.; Blohm, C.; Bokhonov, V.; Bołd, T.; Boos, E. G.; Borras, K.; Boscherini, D.; Bot, D.; Boutle, S. K.; Brock, I.; Brownson, E.; Brugnera, R.; Brümmer, N.; Bruni, A.; Bruni, G.; Brzozowska, B.; Bussey, P. J.; Butterworth, J. M.; Bylsma, B.; Caldwell, A.; Capua, M.; Carlin, R.; Catterall, C. D.; Chekanov, S.; Chwastowski, J.; Ciborowski, J.; Ciesielski, R.; Cifarelli, L.; Cindolo, F.; Contin, A.; Cooper-Sarkar, A. M.; Coppola, N.; Corradi, M.; Corriveau, F.; Costa, M.; D'Agostini, G.; Dal Corso, F.; del Peso, J.; Dementiev, R. K.; De Pasquale, S.; Derrick, M.; Devenish, R. C. E.; Dobur, D.; Dolgoshein, B. A.; Dolinska, G.; Doyle, A. T.; Drugakov, V.; Durkin, L. S.; Dusini, S.; Eisenberg, Y.; Ermolov, P. F.; Eskreys, A.; Fang, S.; Fazio, S.; Ferrando, J.; Ferrero, M. I.; Figiel, J.; Forrest, M.; Foster, B.; Fourletov, S.; Gach, G.; Galas, A.; Gallo, E.; Garfagnini, A.; Geiser, A.; Gialas, I.; Gladilin, L. K.; Gladkov, D.; Glasman, C.; Gogota, O.; Golubkov, Yu. A.; Göttlicher, P.; Grabowska-Bołd, I.; Grebenyuk, J.; Gregor, I.; Grigorescu, G.; Grzelak, G.; Gueta, O.; Gwenlan, C.; Haas, T.; Hain, W.; Hamatsu, R.; Hart, J. C.; Hartmann, H.; Hartner, G.; Hilger, E.; Hochman, D.; Hori, R.; Horton, K.; Hüttmann, A.; Iacobucci, G.; Ibrahim, Z. A.; Iga, Y.; Ingbir, R.; Ishitsuka, M.; Jakob, H.-P.; Januschek, F.; Jimenez, M.; Jones, T. W.; Jüngst, M.; Kadenko, I.; Kahle, B.; Kamaluddin, B.; Kananov, S.; Kanno, T.; Karshon, U.; Karstens, F.; Katkov, I. I.; Kaur, M.; Kaur, P.; Keramidas, A.; Khein, L. A.; Kim, J. Y.; Kisielewska, D.; Kitamura, S.; Klanner, R.; Klein, U.; Koffeman, E.; Kooijman, P.; Korol, Ie.; Korzhavina, I. A.; Kotański, A.; Kötz, U.; Kowalski, H.; Kulinski, P.; Kuprash, O.; Kuze, M.; Lee, A.; Levchenko, B. B.; Levy, A.; Libov, V.; Limentani, S.; Ling, T. Y.; Lisovyi, M.; Lobodzinska, E.; Lohmann, W.; Löhr, B.; Lohrmann, E.; Loizides, J. H.; Long, K. R.; Longhin, A.; Lontkovskyi, D.; Lukina, O. Yu.; Łużniak, P.; Maeda, J.; Magill, S.; Makarenko, I.; Malka, J.; Mankel, R.; Margotti, A.; Marini, G.; Martin, J. F.; Mastroberardino, A.; Mattingly, M. C. K.; Melzer-Pellmann, I.-A.; Miglioranzi, S.; Idris, F. Mohamad; Monaco, V.; Montanari, A.; Morris, J. D.; Mujkic, K.; Musgrave, B.; Nagano, K.; Namsoo, T.; Nania, R.; Nicholass, D.; Nigro, A.; Ning, Y.; Noor, U.; Notz, D.; Nowak, R. J.; Nuncio-Quiroz, A. E.; Oh, B. Y.; Okazaki, N.; Oliver, K.; Olkiewicz, K.; Onishchuk, Yu.; Papageorgiu, K.; Parenti, A.; Paul, E.; Pawlak, J. M.; Pawlik, B.; Pelfer, P. G.; Pellegrino, A.; Perlanski, W.; Perrey, H.; Piotrzkowski, K.; Plucinski, P.; Pokrovskiy, N. S.; Polini, A.; Proskuryakov, A. S.; Przybycień, M.; Raval, A.; Reeder, D. D.; Reisert, B.; Ren, Z.; Repond, J.; Ri, Y. D.; Robertson, A.; Roloff, P.; Ron, E.; Rubinsky, I.; Ruspa, M.; Sacchi, R.; Salii, A.; Samson, U.; Sartorelli, G.; Savin, A. A.; Saxon, D. H.; Schioppa, M.; Schlenstedt, S.; Schleper, P.; Schmidke, W. B.; Schneekloth, U.; Schönberg, V.; Schörner-Sadenius, T.; Schwartz, J.; Sciulli, F.; Shcheglova, L. M.; Shehzadi, R.; Shimizu, S.; Singh, I.; Skillicorn, I. O.; Słomiński, W.; Smith, W. H.; Sola, V.; Solano, A.; Son, D.; Sosnovtsev, V.; Spiridonov, A.; Stadie, H.; Stanco, L.; Stern, A.; Stewart, T. P.; Stifutkin, A.; Stopa, P.; Suchkov, S.; Susinno, G.; Suszycki, L.; Sztuk-Dambietz, J.; Szuba, D.; Szuba, J.; Tapper, A. D.; Tassi, E.; Terrón, J.; Theedt, T.; Tiecke, H.; Tokushuku, K.; Tomalak, O.; Tomaszewska, J.; Tsurugai, T.; Turcato, M.; Tymieniecka, T.; Uribe-Estrada, C.; Vázquez, M.; Verbytskyi, A.; Viazlo, O.; Vlasov, N. N.; Volynets, O.; Walczak, R.; Abdullah, W. A. T. Wan; Whitmore, J. J.; Whyte, J.; Wiggers, L.; Wing, M.; Wlasenko, M.; Wolf, G.; Wolfe, H.; Wrona, K.; Yagües-Molina, A. G.; Yamada, S.; Yamazaki, Y.; Yoshida, R.; Youngman, C.; Żarnecki, A. F.; Zawiejski, L.; Zenaiev, O.; Zeuner, W.; Zhautykov, B. O.; Zhmak, N.; Zhou, C.; Zichichi, A.; Zolko, M.; Zotkin, D. S.; Zulkapli, Z.; ZEUS Collaboration

    2011-03-01

    The energy dependence of the photon-proton total cross section, σtotγp, was determined from ep scattering data collected with the ZEUS detector at HERA at three values of the center-of-mass energy, W, of the γp system in the range 194

  12. 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

  13. 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

  14. 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.

  15. Compositional radial variability in the Saturn's system observed by Cassini-VIMS (INVITED) (Invited)

    NASA Astrophysics Data System (ADS)

    Filacchione, G.; Capaccioni, F.; Clark, R. N.; Brown, R. H.; Cuzzi, J. N.; Buratti, B. J.; Coradini, A.; Lunine, J. I.; Cerroni, P.; Tosi, F.; Ciarniello, M.; Cruikshank, D. P.; Jaumann, R.; Nicholson, P. D.; Stephan, K.; Nelson, R.; Baines, K. H.

    2010-12-01

    From ~2200 disk-integrated observations of the moons and several radial mosaics of the rings acquired by Cassini-VIMS, we have found very striking differences among the various objects in the Saturn system, ranging from the almost uncontaminated and water ice-rich surfaces of Enceladus and Calypso to the metal/organic-rich and red surfaces of Iapetus’ leading hemisphere and Phoebe. In this framework, we have investigated the relationships between the satellite surface composition, orbital distance from Saturn, and average density. In the F ring environment, the inner satellites (Prometheus, Pandora, Janus and Epimetheus) have average surface water ice abundances similar to particles in the C ring and CD but with much less reddening contaminant. Although their orbits are close to the F-ring, Prometheus and Pandora have very evident differences in surface composition: Prometheus is very water ice-rich but at the same time very red at VIS wavelengths. These properties make it very similar to A-B ring particles while Pandora is bluer. Moving outward, the effects of E ring particles, generated by Enceladus plumes become evident as they contaminate surfaces from Mimas to Rhea. We have found some differences between the Lagrangian moons of Tethys: Calypso is much more water ice-rich and bluer with respect to Telesto. Among the outer satellites, moving from Hyperion, to Iapetus and Phoebe, a linear trend is observed relating the decrease of water ice to reddening, with Hyperion resulting as the reddest object of the population. As a further step, we have investigated how these surface properties are correlated with the average densities and dimensions of the moons. Mid-sized icy satellites are in a transition regime, between the high pressure/high density ice phases of Titan and the high porosity/irregular shapes of the minor moons and Hyperion. Low-density (0.5-1.0 g cm-3) satellites show different trends with Prometheus, Pandora and Calypso characterized by high

  16. 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

  17. Computed tomography dosimetry with high-resolution detectors commonly used in radiotherapy - an energy dependence study.

    PubMed

    Liebmann, Mario; Poppe, Bjoern; von Boetticher, Heiner

    2015-09-08

    New methods of dosimetry in computed tomography (CT) X-ray fields require the use of high-resolution detectors instead of pencil-type ionization chambers typically used for CT dose index (CTDI) measurements. This paper presents a study on the suitability of a wide range of ionization chambers, diodes, and a two-dimensional detector array, used primarily in radiation therapy, for CT and cone-beam CT dosimetry. Specifically, the energy dependence of these detectors from 50 kVp up to 125 kVp is reported. All measurements were performed in reference to a calibrated diode for use in this energy region. The radiation quality correction factors provided by the manufacturer were used, depending on the measured half-value layer (HVL) for the particular X-ray beam. Our study demonstrated the general usability of thimble ionization chambers. These thimble ionization chambers showed a maximum variation in energy response of 5%. Ionization chambers with even smaller sensitive volume, and which exhibit similar variation in energy dependence, can be used if higher spatial resolution is required. Furthermore, the investigated detectors are better suited for dosimetry at CT and CBCT units than conventional large volume or flat detectors, due to their rotational symmetry. Nevertheless, a flat detector can be used for certain measurement tasks, such as the acquisition of percent depth-dose curves or beam profiles for nonrotating beams, which are important for beam characterization.

  18. Fully energy-dependent HZETRN (a galactic cosmic-ray transport code)

    NASA Technical Reports Server (NTRS)

    Shinn, Judy L.; John, Sarah; Tripathi, Ram K.; Norbury, John W.; Wilson, John W.; Townsend, Lawrence W.

    1992-01-01

    For extended manned space missions, the radiation shielding design requires efficient and accurate cosmic-ray transport codes that can handle the physics processes in detail. The Langley Research Center galactic cosmic-ray transport code (HZETRN) is currently under development for such design use. The cross sections for the production of secondary nucleons in the existing HZETRN code are energy dependent only for nucleon collisions. The approximation of energy-independent, heavy-ion fragmentation cross section is now removed by implementing a mathematically simplified energy-dependent stepping formalism for heavy ions. The cross section at each computational grid is obtained by linear interpolation from a few tabulated data to minimize computing time. Test runs were made for galactic cosmic-ray transport through a liquid hydrogen shield and a water shield at solar minimum. The results show no appreciable change in total fluxes or computing time compared with energy-independent calculations. Differences in high LET (linear energy transfer) spectra are noted, however, because of the large variation in cross sections at the low-energy region. The high LET components are significantly higher in the new code and have important implications on biological risk estimates for heavy-ion exposure.

  19. Energy Dependence of Electron Anisotropy and Agyrotropy from PIC Simulations of Tail Reconnection

    NASA Astrophysics Data System (ADS)

    Newman, D. L.; Goldman, M. V.; Lapenta, G.; Eastwood, J. P.

    2015-12-01

    MMS is capable of measuring particle distributions with unprecedented temporal resolution. These distributions will aid in the identification of key regions of the reconnecting plasma, such as the electron diffusion region and dipolarization fronts (DFs) in Earth's magnetotail. Electron anisotropy and agyrotropy are particularly useful diagnostics for this purpose. Normally, anisotropy and agyrotropy are defined as properties of the total pressure tensor. However, such global velocity-space measures of the electron distribution can hide detailed energy-dependent variations. Using electron distributions from 2D and 3D PIC simulations of tail reconnection, we employ a combination of 3D velocity-space visualization techniques and energy-dependent anisotropy and agyrotropy measures to analyze the distributions from regions in the vicinity of the reconnection x-line, the magnetic separatricies, and DFs. For example, regions of the reconnection exhaust near a DF can exhibit a nearly isotropic pressure tensor due to the competing influences of low-energy electrons, which contribute disproportionately to the parallel pressure, and high-energy electron, which contribute disproportionately to the perpendicular pressure.

  20. Energy Dependence and Scaling Property of Localization Length near a Gapped Flat Band

    NASA Astrophysics Data System (ADS)

    Ge, Li; Tureci, Hakan

    Using a tight-binding model for a one-dimensional Lieb lattice, we show that the localization length near a gapped flat band behaves differently from the typical Urbach tail in a band gap: instead of reducing monotonically as the energy E moves away from the flat band energy Ef, the presence of the flat band causes a nonmonotonic energy dependence of the localization length. This energy dependence follows a scaling property when the energy is within the spread (W) of uniformly distributed diagonal disorder, i.e. the localization length is only a function of (E-Ef)/W. Several other lattices are compared to distinguish the effect of the flat band on the localization length, where we eliminate, shift, or duplicate the flat band, without changing the dispersion relations of other bands. Using the top right element of the Green's matrix, we derive an analytical relation between the density of states and the localization length, which shines light on these properties of the latter, including a summation rule for its inverse. This work is partially supported by NSF under Grant No. DMR-1506987.

  1. Classical and quantum dynamics of a perfect fluid scalar-energy dependent metric cosmology

    NASA Astrophysics Data System (ADS)

    Khodadi, M.; Nozari, K.; Vakili, B.

    2016-05-01

    Inspired from the idea of minimally coupling of a real scalar field to geometry, we investigate the classical and quantum models of a flat energy-dependent FRW cosmology coupled to a perfect fluid in the framework of the scalar-rainbow metric gravity. We use the standard Schutz' representation for the perfect fluid and show that under a particular energy-dependent gauge fixing, it may lead to the identification of a time parameter for the corresponding dynamical system. It is shown that, under some circumstances on the minisuperspace prob energy, the classical evolution of the of the universe represents a late time expansion coming from a bounce instead of the big-bang singularity. Then we go forward by showing that this formalism gives rise to a Schrödinger-Wheeler-DeWitt equation for the quantum-mechanical description of the model under consideration, the eigenfunctions of which can be used to construct the wave function of the universe. We use the resulting wave function in order to investigate the possibility of the avoidance of classical singularities due to quantum effects by means of the many-worlds and Bohmian interpretation of quantum cosmology.

  2. 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.

  3. 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.

  4. The composition of thermal and hot ions observed by the GEOS-1 and -2 spacecraft

    NASA Astrophysics Data System (ADS)

    Balsiger, H.; Geiss, J.; Young, D. T.

    1983-01-01

    The GEOS-1 and -2 ion composition experiments have surveyed the plasma composition of the near equatorial inner magnetosphere in the energy per charge range below 16 keV/e since May 1977. In this paper, a review is provided of the contributions of these studies to plasmasphere and ring current composition, to wave particle interactions, to the questions of large scale plasma circulation and to origins of magnetospheric ions.

  5. 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.

  6. Probing the chemical composition of the Z < 1 intergalactic medium with observations and simulations

    NASA Astrophysics Data System (ADS)

    Cooksey, Kathy L.

    2009-09-01

    Metals are produced in the stars in the galaxies, and a variety of feedback processes move metals from the sites of production into the intergalactic medium (IGM), enriching the material for future generations of stars. The signature of this process is etched in the recycled gas: its metallicity, elemental abundances, density, distribution, etc. The study of the low- redshift, z <, IGM is the study of the last eight-billion years of cosmic chemical evolution and all prior enrichment. In this thesis, I characterize the cosmic enrichment cycle with the use of observations and simulations. The gas is observed through quasar absorption- line spectroscopy. As the light of a distant quasar travels to us, intervening clouds of gas absorb the light at wavelengths characteristic, albeit redshifted, of the elements in the clouds. By identifying and modeling the elements associated with the absorption systems, I learn the ionic composition and density of the cosmic web (voids, filaments, and/or groups) along the line of sight. >From a detailed study of a single sightline, I observe a multi-phase IGM, with kinematically-distinct, hot and warm components ( T [approximate] 10 5.5 K and 10 4 K, respectively). By correlating the absorption systems with a complementary galaxy survey of the field around the background quasar, I find that the IGM systems arise in a variety of galactic environments. The metal- lines systems all have L > 0.1 L [low *] galaxies within a few hundred kiloparsecs, which suggests this is the distance to which galactic feedback processes typically disperse metals. I conduct a large, blind survey for triply-ionized carbon (C IV) absorption at z < 1 in the spectra of 49 low-redshift quasars and compare their propertie with those detected at z > 1. The mass density in C IV doublets with 13 < = log N (C +3 ) <= 15 at z < 1 has increased by a factor of 2.8 ± 0.7 over the error- weighted mean of the 1.5 < z < 5 measurements, where the mass density has not evolved

  7. The Influence of Aerosol Composition on Photolysis Rates Based on Airborne Observations

    NASA Astrophysics Data System (ADS)

    Corr, C.; Barrick, J. D. W.; Beyersdorf, A. J.; Chen, G.; Crawford, J. H.; Jordan, C. E.; Moore, R.; Shook, M.; Thornhill, K. L., II; Winstead, E.; Ziemba, L. D.; Madronich, S.; Anderson, B. E.

    2015-12-01

    The potential variability in modeled photolysis rates introduced by aerosol optical properties measured at visible wavelengths is presented here. Aerosol scattering and absorption were measured aboard the NASA P-3B aircraft during the Deriving Information on Surface conditions from Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) using a TSI Nephelometer and a Radiance Research Particle Soot Absorption Photometer (PSAP), respectively. To isolate the effect of aerosols on photolysis rates, cloud-free case studies were identified using aircraft videos for the four DISCOVER-AQ deployments: Baltimore, MD-Washington, D.C. in July 2011, the California Central Valley in January/February 2013, Houston, TX in September 2013, and Denver, CO in July 2014. For these case studies, absorption measurements at 470 and 532 nm were extrapolated to the Nephelometer wavelengths (450 and 550nm) using the 470-532nm absorption Angstrom exponent (AAE470-532) to calculate aerosol extinction and SSAs at these wavelengths. Photolysis rates were modeled using the Tropospheric Ultraviolet model version 5.2 (TUV 5.2) for three scenarios: 1) an aerosol-free case, 2) using a spectrally-flat SSA at 550nm and 3) using a spectrally-dependent SSA derived from scattering and absorption measurements. Modeled photolysis rates were compared to those measured aboard the P-3B during DISCOVER-AQ. The relationship between airborne measurements of water soluble organic carbon (WSOC) made by a Particle-Into-Liquid-Sampler (PILS), AAE470-532 and model/measurement discrepancies were explored to assess the influence of aerosol composition on photolysis rates. Additional comparisons between photolysis rates modeled with vertically-resolved aerosol optical properties and those modeled using column-average values were performed to assess the influence of aerosol vertical distribution on photolysis rates.

  8. Using XMM-Newton to study the energy-dependent variability of H 1743-322 during its 2014 outburst

    NASA Astrophysics Data System (ADS)

    Stiele, H.; Yu, W.

    2016-08-01

    Black hole transients evolve during bright outbursts, showing distinct changes in their spectral and variability properties. These changes are interpreted as evidence for changes in the accretion flow and in the X-ray-emitting regions. We obtained an anticipated XMM-Newton Target of Opportunity observation of H 1743-322 during its outburst in 2014 September. Based on data from eight outbursts observed in the last 10 yr, we expected to catch the start of the hard-to-soft state transition. The fact that neither the general shape of the observed power density spectrum nor the characteristic frequency shows an energy dependence implies that the source remained in the low-hard state at the time of our observation near outburst peak. The spectral properties agree with the source being in the low-hard state, and a Swift/XRT monitoring of the outburst revealed that H 1743-322 stayed in the low-hard state during the entire outburst (known as a `failed outburst'). Here we derive the averaged QPO waveform and obtain phase-resolved spectra. A comparison of the phase-resolved spectra with the phase-averaged energy spectrum reveals spectral pivoting. We compare variability on long and short time-scales using covariance spectra and find that the covariance ratio does not show an increase towards lower energies. In other binaries an increase has been found. There are two possible explanations: either the absence of additional disc variability on longer time-scales is related to the high inclination of H 1743-322 compared with other black hole X-ray binaries, or it is the reason why we observe H 1743-322 during a failed outburst. More data on failed outbursts and on high-inclination sources will be needed in order to investigate these two possibilities further.

  9. 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

  10. 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

  11. Nonlinearly charged dilatonic black holes and their Brans-Dicke counterpart: energy dependent spacetime

    NASA Astrophysics Data System (ADS)

    Hendi, S. H.; Talezadeh, M. S.

    2017-01-01

    Regarding the wide applications of dilaton gravity in the presence of electrodynamics, we introduce a suitable Lagrangian for the coupling of dilaton with gauge field. There are various Lagrangians which show the coupling between scalar fields and electrodynamics with correct special situations. In this paper, taking into account conformal transformation of Brans-Dicke theory with an electrodynamics Lagrangian, we show that how scalar field should couple with electrodynamics in dilaton gravity. In other words, in order to introduce a correct Lagrangian of dilaton gravity, one should check at least two requirements: compatibility with Brans-Dicke theory and appropriate special situations. Finally, we apply the mentioned method to obtain analytical solutions of dilaton-Born-Infeld and Brans-Dicke-Born-Infeld theories with energy dependent spacetime.

  12. An energy-dependent numerical model for the condensation probability, γj

    NASA Astrophysics Data System (ADS)

    Kerby, Leslie M.

    2017-04-01

    The "condensation" probability, γj, is an important variable in the preequilibrium stage of nuclear spallation reactions. It represents the probability that pj excited nucleons (excitons) will "condense" to form complex particle type j in the excited residual nucleus. It has a significant impact on the emission width, or probability of emitting fragment type j from the residual nucleus. Previous formulations for γj were energy-independent and valid for fragments up to 4He only. This paper explores the formulation of a new model for γj, one which is energy-dependent and valid for up to 28Mg, and which provides improved fits compared to experimental fragment spectra.

  13. The energy dependence and surface morphology of Kapton (trademark) degradation under atomic oxygen bombardment

    NASA Technical Reports Server (NTRS)

    Ferguson, D. C.

    1984-01-01

    Data from laboratory simulations and from samples returned from STS-8 are used to derive the energy dependence of the mass loss rate of Kapton under atomic oxygen bombardment and to discuss the development of surface structure and its effect on erosion rates. It is concluded that all the laboratory data from discharge and flow tubes and from accelerated beams, along with the orbital data from STS-3 through STS-8, can be accommodated by a rate of mass loss that varies with impact energy normal to the surface. It is hypothesized that increases of mass loss rate with exposure time may be due to trapping of the incoming atoms by the surface structure which develops.

  14. Relativistic mean-field model with energy dependent self-energies

    SciTech Connect

    Antic, S.; Typel, S.

    2015-02-24

    Conventional relativistic mean-field theory is extended with the introduction of higher-order derivative couplings of nucleons with the meson fields. The Euler-Lagrange equations follow from the principle of stationary action. From invariance principles of the Lagrangian density the most general expressions for the conserved current and energy-momentum tensor are derived. The nucleon self-energies show the explicit dependence on the meson fields. They contain additional regulator functions which describe the energy dependence. The density dependence of meson-nucleon couplings causes the apperance of additional rearrangement contributions in the self-energies. The equation of state of infinite nuclear matter is obtained and the thermodynamical consistency of the model is demonstrated. This model is applied to the description of spherical, non-rotating stars in β-equilibrium. Stellar structure is calculated by solving the Tolman-Oppenheimer-Volkov (TOV) equations. The results for neutron stars are shown in terms of mass-radius relations.

  15. An energy-dependent numerical model for the condensation probability, γj

    DOE PAGES

    Kerby, Leslie Marie

    2016-12-09

    The “condensation” probability, γj, is an important variable in the preequilibrium stage of nuclear spallation reactions. It represents the probability that pj excited nucleons (excitons) will “condense” to form complex particle type j in the excited residual nucleus. In addition, it has a significant impact on the emission width, or probability of emitting fragment type j from the residual nucleus. Previous formulations for γj were energy-independent and valid for fragments up to 4He only. This paper explores the formulation of a new model for γj, one which is energy-dependent and valid for up to 28Mg, and which provides improved fitsmore » compared to experimental fragment spectra.« less

  16. Observation

    ERIC Educational Resources Information Center

    Helfrich, Shannon

    2016-01-01

    Helfrich addresses two perspectives from which to think about observation in the classroom: that of the teacher observing her classroom, her group, and its needs, and that of the outside observer coming into the classroom. Offering advice from her own experience, she encourages and defends both. Do not be afraid of the disruption of outside…

  17. Observations

    ERIC Educational Resources Information Center

    Joosten, Albert Max

    2016-01-01

    Joosten begins his article by telling us that love and knowledge together are the foundation for our work with children. This combination is at the heart of our observation. With this as the foundation, he goes on to offer practical advice to aid our practice of observation. He offers a "List of Objects of Observation" to help guide our…

  18. Application of Local Time Dependent Ion Composition to Observations, Modeling, and Effects of Electromagnetic Ion Cyclotron Waves

    NASA Astrophysics Data System (ADS)

    Lee, J. H.; Angelopoulos, V.; Chen, L.; Thorne, R. M.

    2014-12-01

    Numerous global magnetospheric studies on electromagnetic ion cyclotron (EMIC) waves have revealed the typical wave properties observed throughout the Earth's magnetosphere. The observed trends in the wave properties at various geocentric distances and local time sectors, although in general agreement, elude satisfactory explanation without further details on the ambient plasma properties, the low-energy (few to ~100 eV) ions in particular. Recent studies also described techniques to deduce the presence and properties of low-energy ions and the application of such a technique to THEMIS (Time History of Events and Macroscale Interactions during Substorms) data has revealed the typical low-energy ion compositional properties throughout the Earth's magnetosphere. Motivated by the recent work on EMIC waves and low-energy ion composition, we analyze typical wave cases observed at each local time sector by the THEMIS satellites and apply the composition techniques or the statistical low-energy ion composition data to constrain the low-energy components in modeling of each wave case in the context of linear hot plasma theory. We find that the observed waves are modeled well with hot plasma theory and both are fully consistent with the composition of the ambient plasma. Our results suggest that combined ion composition and wave measurements are critical for further assessment of the effects of the waves on energetic particles. In the cases we report on here, we find the waves could resonantly interact with electrons at energies in excess of 2 MeV and therefore do not have an effect on the dominant trapped electron population.

  19. 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

  20. The compositional and thermal structure of the lithosphere from thermodynamically-constrained multi-observable probabilistic inversion

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

    Our capacity to image and characterize the thermal and compositional structure of the lithospheric and sublithospheric upper mantle is a fundamental prerequisite for understanding the formation and evolution of the lithosphere, the interaction between the crust-mantle and lithosphere-asthenosphere systems, and the nature of the lithosphere-asthenosphere boundary (LAB). In this context, the conversion of geophysical observables (e.g. travel-time data, gravity anomalies, etc) into robust estimates of the true physical and chemical state of the Earth's interior plays a major role. Unfortunately, available methods/software used to make such conversions are not well suited to deal with one or more of the following problems: 1) Strong non-linearity of the system. Traditional linearized inversions do not generally provide reliable estimates. 2) The temperature effect on geophysical observables is much greater than the compositional effect, therefore the latter is much harder to isolate. 3) Non-uniqueness of the compositional field. Different compositions can fit equally well seismic and potential field observations. 4) Strong correlations between physical parameters and geophysical observables complicate the inversion procedure and their effects are poorly understood. 5) Trade-off between temperature and composition in wave speeds. In this contribution we present a new full-3D multi-observable inversion method particularly designed to circumvent these problems. Some other key aspects of the method are: a) it combines multiple datasets (ambient noise tomography, receiver function analysis, body-wave tomography, magnetotelluric, geothermal, petrological, and gravity) in a single thermodynamic-geophysical framework, b) a general probabilistic (Bayesian) formulation is used to appraise the data, c) neither initial models nor well-defined a priori information is required, and d) it provides realistic uncertainty estimates. Both synthetic models and preliminary results for real

  1. 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

  2. Observation

    ERIC Educational Resources Information Center

    Kripalani, Lakshmi A.

    2016-01-01

    The adult who is inexperienced in the art of observation may, even with the best intentions, react to a child's behavior in a way that hinders instead of helping the child's development. Kripalani outlines the need for training and practice in observation in order to "understand the needs of the children and...to understand how to remove…

  3. ACCURATE MEASUREMENT OF THE ENERGY DEPENDENCE OF THE PROCESS e+ + e- → e± + e∓, IN THE s-RANGE 1.44-9.0 GeV2

    NASA Astrophysics Data System (ADS)

    Bernardini, M.; Bollini, D.; Brunini, P. L.; Fiorentino, E.; Massam, T.; Monari, L.; Palmonari, F.; Rimondi, F.; Zichichi, A.

    The analysis of 12 827 e+ + e- → e± + e∓ events observed in the s-range 1.44-9.0 GeV2 allows measurement of the energy dependence of the cross-section for the most typical QED process, with ±2% accuracy. Within this limit the data follow QED, with first-order radiative corrections included.

  4. 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

  5. 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.

  6. Tropical deep convection and its impact on composition in global and mesoscale models - Part 1: Meteorology and comparison with observations.

    NASA Astrophysics Data System (ADS)

    Russo, M. R.; Marécal, V.; Hoyle, C. R.; Arteta, J.; Chemel, C.; Chipperfield, M. P.; Dessens, O.; Feng, W.; Hosking, J. S.; Telford, P. J.; Wild, O.; Yang, X.; Pyle, J. A.

    2010-08-01

    Tropical convection is a very important atmospheric process acting on the water cycle, radiative budget of the atmosphere and air composition of the upper troposphere and lower stratosphere (UTLS), and it affects a broad range of spatial and temporal scales. The fast vertical transport in convective plumes can efficiently redistribute water vapour and pollutants up to the Tropical Tropopause Layer (TTL), and therefore affect the composition of the lower stratosphere. Chemistry Climate Models and Chemistry Transport Models are routinely used to study chemical processes in the atmosphere. In these models convection and convective transport of tracers are parameterised, and due to the interplay of chemical and dynamical processes, it has proven difficult to evaluate the convective transport of chemical species by comparison with observed chemical fields. In this work we investigate different characteristics of tropical convection by using convective proxies from many independent observational datasets (including surface precipitation rates, cloud top pressure and OLR). We use observations to analyse the seasonal cycle and geographical preferences of convection, and its impact on water vapour. Using highly temporally resolved cloud top data we calculate the frequency distribution of high clouds in three tropical regions. The observational data is used as a benchmark for a number of numerical models, with a view to assess the ability of models to reproduce the seasonality, preferential location and vertical extent of tropical convection. Finally we discuss the implications of our findings on modelling the composition of the upper troposphere and lower stratosphere.

  7. Beyond the Lorentzian Model in Quantum Transport: Energy-Dependent Resonance Broadening in Molecular Junctions

    NASA Astrophysics Data System (ADS)

    Liu, Zhenfei; Neaton, Jeffrey B.

    In quantum transport calculations, transmission functions of molecular junctions, as well as spectral functions of metal-organic interfaces, often feature peaks originating from molecular resonances. These resonance peaks are often assumed to be Lorentzian, with an energy-independent broadening function Γ. However, in the general case, the wide-band-limit breaks down, and the Lorentzian approximation is no longer valid. Here, we develop a new energy-dependent broadening function Γ (E) , based on diagonalization of non-Hermitian matrices within a non-equilbrium Green's function (NEGF) formalism. As defined, Γ (E) can describe resonances of non-Lorentzian nature and can be decomposed into components associated with the left and right leads, respectively; and it is particularly useful in understanding transport properties in terms of molecular orbitals in asymmetric junctions. We compute this quantity via an ab initio NEGF approach based on density functional theory and illustrate its utility with several junctions of experimental relevance, including recent work on rectification in Au-graphite junctions. This work is supported by the DOE, and computational resources are provided by NERSC.

  8. A study of the energy dependence of the underlying event in proton-antiproton collisions

    DOE PAGES

    Aaltonen, T.

    2015-11-23

    We study charged particle production (pT > 0.5 GeV/c, |η| < 0.8) in proton-antiproton collisions at 300 GeV, 900 GeV, and 1.96 TeV. We use the direction of the charged particle with the largest transverse momentum in each event to define three regions of η-Φspace; “toward”, “away”, and “transverse”. Furthermore, the average number and the average scalar pT sum of charged particles in the transverse region are sensitive to the modeling of the “underlying event”. The transverse region is divided into a MAX and MIN transverse region, which helps separate the “hard component” (initial and final-state radiation) from the “beam-beammore » remnant” and multiple parton interaction components of the scattering. We found that the center-of-mass energy dependence of the various components of the event are studied in detail. The data presented here can be used to constrain and improve QCD Monte Carlo models, resulting in more precise predictions at the LHC energies of 13 and 14 TeV.« less

  9. A study of the energy dependence of the underlying event in proton-antiproton collisions

    SciTech Connect

    Aaltonen, T.

    2015-11-23

    We study charged particle production (pT > 0.5 GeV/c, |η| < 0.8) in proton-antiproton collisions at 300 GeV, 900 GeV, and 1.96 TeV. We use the direction of the charged particle with the largest transverse momentum in each event to define three regions of η-Φspace; “toward”, “away”, and “transverse”. Furthermore, the average number and the average scalar pT sum of charged particles in the transverse region are sensitive to the modeling of the “underlying event”. The transverse region is divided into a MAX and MIN transverse region, which helps separate the “hard component” (initial and final-state radiation) from the “beam-beam remnant” and multiple parton interaction components of the scattering. We found that the center-of-mass energy dependence of the various components of the event are studied in detail. The data presented here can be used to constrain and improve QCD Monte Carlo models, resulting in more precise predictions at the LHC energies of 13 and 14 TeV.

  10. Study of the energy dependence of the underlying event in proton-antiproton collisions

    SciTech Connect

    Nodulman, L.; Aaltonen, T; Albrow, M; Amerio, S.; Amidei, D; Anastassov, A.; Annovi, A; Antos, J; Apollinari, G.; Appel, J A; Arisawa, T

    2015-11-23

    We study charged particle production (p(T) > 0.5 GeV/c, vertical bar eta vertical bar < 0.8) in proton-antiproton collisions at total center-of-mass energies root s = 300 GeV, 900 GeV, and 1.96 TeV. We use the direction of the charged particle with the largest transverse momentum in each event to define three regions of eta - phi space: "toward", "away", and "transverse." The average number and the average scalar pT sum of charged particles in the transverse region are sensitive to the modeling of the "underlying event." The transverse region is divided into a MAX and MIN transverse region, which helps separate the "hard component" (initial and final-state radiation) from the "beam-beam remnant" and multiple parton interaction components of the scattering. The center-of-mass energy dependence of the various components of the event is studied in detail. The data presented here can be used to constrain and improve QCD Monte Carlo models, resulting in more precise predictions at the LHC energies of 13 and 14 TeV.

  11. Subpicosecond Photon-Energy-Dependent Hole Transfer from PbS Quantum Dots to Conjugated Polymers.

    PubMed

    Colbert, Adam E; Jedlicka, Erin; Wu, Wenbi; Ginger, David S

    2016-12-15

    We use transient absorption (TA) spectroscopy to study the origin of photon-energy dependent hole transfer yields in blends of PbS quantum dots with the conjugated polymer poly(3-hexylthiophene-2,5-diyl) (P3HT). We selectively excite only the quantum dots at two different wavelengths and measure the polymer ground state bleach resulting from the transfer of photoexcited holes. The higher photon-energy pump shows a greater prompt yield of hole transfer compared to the lower photon-energy excitation, on time scales sufficient to out-compete hot carrier cooling in lead chalcogenide quantum dots. We interpret the results as evidence that the excess energy of nonthermalized, or "hot," excitons resulting from higher photon-energy excitation allows more efficient charge transfer to the polymer in these systems. The data also demonstrate slow charge transfer rates, up to ∼1 ns, of the relaxed excitations on the PbS dots. These findings help to clarify the role of excess photon energy and carrier relaxation dynamics on free carrier generation in donor/acceptor solar cells.

  12. Centrality and energy dependence of charged-particle multiplicities in heavy ion collisions in the context of elementary reactions

    SciTech Connect

    Back, B. B.; Wuosmaa, A. H.; Baker, M. D.; Barton, D. S.; Carroll, A.; Gushue, S.; Heintzelman, G. A.; Holzman, B.; Pak, R.; Remsberg, L. P.; Steinberg, P.; Sukhanov, A.; Betts, R. R.; Garcia, E.; Halliwell, C.; Hofman, D. J.; Hollis, R. S.; Iordanova, A.; Kucewicz, W.; McLeod, D.

    2006-08-15

    The PHOBOS experiment at the BNL Relativistic Heavy Ion Collider has measured the total multiplicity of primary charged particles as a function of collision centrality in Au+Au collisions at {radical}(s{sub NN})= 19.6, 130, and 200 GeV. An approximate independence of / on the number of participating nucleons is observed, reminiscent of 'wounded nucleon' scaling (N{sub ch}{proportional_to}N{sub part}) observed in proton-nucleus collisions. Unlike p+A, the constant of proportionality does not seem to be set by the pp/pp data at the same energy. Rather, there seems to be a surprising correspondence with the total multiplicity measured in e{sup +}e{sup -} annihilations, as well as the rapidity shape measured over a large range. The energy dependence of the integrated multiplicity per participant pair shows that e{sup +}e{sup -} and A+A data agree over a large range of center-of-mass energies ({radical}(s)>20 GeV), and pp/pp data can be brought to agree approximately with the e{sup +}e{sup -} data by correcting for the typical energy taken away by leading particles. This is suggestive of a mechanism for soft particle production that depends mainly on the amount of available energy. It is conjectured that the dominant distinction between A+A and p+p collisions is the multiple collisions per participant, which appears to be sufficient to substantially reduce the energy taken away by leading particles.

  13. Variation of the ion composition in the ring current during magnetic storms: Van Allen Probes observations

    NASA Astrophysics Data System (ADS)

    Luo, Hao; Du, Aimin; Ge, Yasong; Cao, Xin; Zhang, Ying; Wang, Yuan

    2015-04-01

    It has been reported that the energy density of the oxygen ions in the ring current region will show more enhancements than protons during magnetic storms. Knowing how the ion composition changes during a magnetic storm is important for understanding the dynamic processes in the inner magnetosphere. By using ion flux data from HOPE and RBSPICE instruments on board the Van Allen probes, we study the energy density variation of both protons and oxygen ions during fifteen strong magnetic storms (minimum Dst < -80 nT) happened during year 2013 to 2014. Results provide important details about the ion composition at different storm stages and different magnetic local times. Results also give important indications about the ion acceleration in the inner magnetosphere and the source of the ring current ions during the magnetic storms.

  14. Energy-Dependent Scintillation Pulse Shape and Proportionality of Decay Components for CsI:Tl: Modeling with Transport and Rate Equations

    NASA Astrophysics Data System (ADS)

    Lu, X.; Gridin, S.; Williams, R. T.; Mayhugh, M. R.; Gektin, A.; Syntfeld-Kazuch, A.; Swiderski, L.; Moszynski, M.

    2017-01-01

    Relatively recent experiments on the scintillation response of CsI:Tl have found that there are three main decay times of about 730 ns, 3 μ s , and 16 μ s , i.e., one more principal decay component than had been previously reported; that the pulse shape depends on gamma-ray energy; and that the proportionality curves of each decay component are different, with the energy-dependent light yield of the 16 -μ s component appearing to be anticorrelated with that of the 0.73 -μ s component at room temperature. These observations can be explained by the described model of carrier transport and recombination in a particle track. This model takes into account processes of hot and thermalized carrier diffusion, electric-field transport, trapping, nonlinear quenching, and radiative recombination. With one parameter set, the model reproduces multiple observables of CsI:Tl scintillation response, including the pulse shape with rise and three decay components, its energy dependence, the approximate proportionality, and the main trends in proportionality of different decay components. The model offers insights on the spatial and temporal distributions of carriers and their reactions in the track.

  15. AMPTE/CCE observations of the plasma composition below 17 keV during the September 4, 1984 magnetic storm

    NASA Astrophysics Data System (ADS)

    Shelley, E. G.; Klumpar, D. M.; Peterson, W. K.; Ghielmetti, A.; Balsiger, H.; Geiss, J.; Rosenbauer, H.

    1985-05-01

    Observations from the Hot Plasma Composition Experiment on the AMPTE/CCE spacecraft during the magnetic storm of 4-5 September 1984 reveal that significant injection of ions of terrestrial origin accompanied the storm development. The compression of the magnetosphere at storm sudden commencement carried the magnetopause inside the CCE orbit clearly revealing the shocked solar wind plasma. A build up of suprathermal ions is observed near the plasmapause during the storm main phase and recovery phase. Pitch angle distributions in the ring current during the main phase show differences between H(+) and O(+) that suggest mass dependent injection, transport and/or loss processes.

  16. AMPTE/CCE observations of the plasma composition below 17 keV during the September 4, 1984 magnetic storm

    NASA Technical Reports Server (NTRS)

    Shelley, E. G.; Klumpar, D. M.; Peterson, W. K.; Ghielmetti, A.; Balsiger, H.; Geiss, J.; Rosenbauer, H.

    1985-01-01

    Observations from the Hot Plasma Composition Experiment on the AMPTE/CCE spacecraft during the magnetic storm of 4-5 September 1984 reveal that significant injection of ions of terrestrial origin accompanied the storm development. The compression of the magnetosphere at storm sudden commencement carried the magnetopause inside the CCE orbit clearly revealing the shocked solar wind plasma. A build up of suprathermal ions is observed near the plasmapause during the storm main phase and recovery phase. Pitch angle distributions in the ring current during the main phase show differences between H(+) and O(+) that suggest mass dependent injection, transport and/or loss processes.

  17. AMPTE/CCE observations of the plasma composition below 17 keV during the September 4, 1984 magnetic storm

    SciTech Connect

    Shelley, E.G.; Klumpar, D.M.; Peterson, W.K.; Ghielmetti, A.; Balsiger, H.; Geiss, J.; Rosenbauer, H.

    1985-05-01

    Observations from the Hot Plasma Composition Experiment on the AMPTE/CCE spacecraft during the magnetic storm of 4-5 September 1984 reveal that significant injection of ions of terrestrial origin accompanied the storm development. The compression of the magnetosphere at storm sudden commencement carried the magnetopause inside the CCE orbit clearly revealing the shocked solar wind plasma. A build up of suprathermal ions is observed near the plasmapause during the storm main phase and recovery phase. Pitch angle distributions in the ring current during the main phase show differences between H(+) and O(+) that suggest mass dependent injection, transport and/or loss processes. 9 references.

  18. Transverse-momentum and collision-energy dependence of high-pT hadron suppression in Au+Au collisions at ultrarelativistic energies.

    PubMed

    Adams, J; Adler, C; Aggarwal, M M; Ahammed, Z; Amonett, J; Anderson, B D; Anderson, M; Arkhipkin, D; Averichev, G S; Badyal, S K; Balewski, J; Barannikova, O; Barnby, L S; Baudot, J; Bekele, S; Belaga, V V; Bellwied, R; Berger, J; Bezverkhny, B I; Bhardwaj, S; Bhaskar, P; Bhati, A K; Bichsel, H; Billmeier, A; Bland, L C; Blyth, C O; Bonner, B E; Botje, M; Boucham, A; Brandin, A; Bravar, A; Cadman, R V; Cai, X Z; Caines, H; Calderón de la Barca Sánchez, M; Carroll, J; Castillo, J; Castro, M; Cebra, D; Chaloupka, P; Chattopadhyay, S; Chen, H F; Chen, Y; Chernenko, S P; Cherney, M; Chikanian, A; Choi, B; Christie, W; Coffin, J P; Cormier, T M; Cramer, J G; Crawford, H J; Das, D; Das, S; Derevschikov, A A; Didenko, L; Dietel, T; Dong, X; Draper, J E; Drees, K A; Du, F; Dubey, A K; Dunin, V B; Dunlop, J C; Dutta Majumdar, M R; Eckardt, V; Efimov, L G; Emelianov, V; Engelage, J; Eppley, G; Erazmus, B; Fachini, P; Faine, V; Faivre, J; Fatemi, R; Filimonov, K; Filip, P; Finch, E; Fisyak, Y; Flierl, D; Foley, K J; Fu, J; Gagliardi, C A; Ganti, M S; Gagunashvili, N; Gans, J; Gaudichet, L; Germain, M; Geurts, F; Ghazikhanian, V; Ghosh, P; Gonzalez, J E; Grachov, O; Grigoriev, V; Gronstal, S; Grosnick, D; Guedon, M; Guertin, S M; Gupta, A; Gushin, E; Gutierrez, T D; Hallman, T J; Hardtke, D; Harris, J W; Heinz, M; Henry, T W; Heppelmann, S; Herston, T; Hippolyte, B; Hirsch, A; Hjort, E; Hoffmann, G W; Horsley, M; Huang, H Z; Huang, S L; Humanic, T J; Igo, G; Ishihara, A; Jacobs, P; Jacobs, W W; Janik, M; Johnson, I; Jones, P G; Judd, E G; Kabana, S; Kaneta, M; Kaplan, M; Keane, D; Kiryluk, J; Kisiel, A; Klay, J; Klein, S R; Klyachko, A; Kollegger, T; Konstantinov, A S; Kopytine, M; Kotchenda, L; Kovalenko, A D; Kramer, M; Kravtsov, P; Krueger, K; Kuhn, C; Kulikov, A I; Kumar, A; Kunde, G J; Kunz, C L; Kutuev, R Kh; Kuznetsov, A A; Lamont, M A C; Landgraf, J M; Lange, S; Lansdell, C P; Lasiuk, B; Laue, F; Lauret, J; Lebedev, A; Lednický, R; Leontiev, V M; LeVine, M J; Li, C; Li, Q; Lindenbaum, S J; Lisa, M A; Liu, F; Liu, L; Liu, Z; Liu, Q J; Ljubicic, T; Llope, W J; Long, H; Longacre, R S; Lopez-Noriega, M; Love, W A; Ludlam, T; Lynn, D; Ma, J; Ma, Y G; Magestro, D; Mahajan, S; Mangotra, L K; Mahapatra, D P; Majka, R; Manweiler, R; Margetis, S; Markert, C; Martin, L; Marx, J; Matis, H S; Matulenko, Yu A; McShane, T S; Meissner, F; Melnick, Yu; Meschanin, A; Messer, M; Miller, M L; Milosevich, Z; Minaev, N G; Mironov, C; Mishra, D; Mitchell, J; Mohanty, B; Molnar, L; Moore, C F; Mora-Corral, M J; Morozov, V; de Moura, M M; Munhoz, M G; Nandi, B K; Nayak, S K; Nayak, T K; Nelson, J M; Nevski, P; Nikitin, V A; Nogach, L V; Norman, B; Nurushev, S B; Odyniec, G; Ogawa, A; Okorokov, V; Oldenburg, M; Olson, D; Paic, G; Pandey, S U; Pal, S K; Panebratsev, Y; Panitkin, S Y; Pavlinov, A I; Pawlak, T; Perevoztchikov, V; Peryt, W; Petrov, V A; Phatak, S C; Picha, R; Planinic, M; Pluta, J; Porile, N; Porter, J; Poskanzer, A M; Potekhin, M; Potrebenikova, E; Potukuchi, B V K S; Prindle, D; Pruneau, C; Putschke, J; Rai, G; Rakness, G; Raniwala, R; Raniwala, S; Ravel, O; Ray, R L; Razin, S V; Reichhold, D; Reid, J G; Renault, G; Retiere, F; Ridiger, A; Ritter, H G; Roberts, J B; Rogachevski, O V; Romero, J L; Rose, A; Roy, C; Ruan, L J; Rykov, V; Sahoo, R; Sakrejda, I; Salur, S; Sandweiss, J; Savin, I; Schambach, J; Scharenberg, R P; Schmitz, N; Schroeder, L S; Schweda, K; Seger, J; Seliverstov, D; Seyboth, P; Shahaliev, E; Shao, M; Sharma, M; Shestermanov, K E; Shimanskii, S S; Singaraju, R N; Simon, F; Skoro, G; Smirnov, N; Snellings, R; Sood, G; Sorensen, P; Sowinski, J; Spinka, H M; Srivastava, B; Stanislaus, S; Stock, R; Stolpovsky, A; Strikhanov, M; Stringfellow, B; Struck, C; Suaide, A A P; Sugarbaker, E; Suire, C; Sumbera, M; Surrow, B; Symons, T J M; Szanto de Toledo, A; Szarwas, P; Tai, A; Takahashi, J; Tang, A H; Thein, D; Thomas, J H; Tikhomirov, V; Tokarev, M; Tonjes, M B; Trainor, T A; Trentalange, S; Tribble, R E; Trivedi, M D; Trofimov, V; Tsai, O; Ullrich, T; Underwood, D G; Van Buren, G; VanderMolen, A M; Vasiliev, A N; Vasiliev, M; Vigdor, S E; Viyogi, Y P; Voloshin, S A; Waggoner, W; Wang, F; Wang, G; Wang, X L; Wang, Z M; Ward, H; Watson, J W; Wells, R; Westfall, G D; Whitten, C; Wieman, H; Willson, R; Wissink, S W; Witt, R; Wood, J; Wu, J; Xu, N; Xu, Z; Xu, Z Z; Yakutin, A E; Yamamoto, E; Yang, J; Yepes, P; Yurevich, V I; Zanevski, Y V; Zborovský, I; Zhang, H; Zhang, H Y; Zhang, W M; Zhang, Z P; Zołnierczuk, P A; Zoulkarneev, R; Zoulkarneeva, J; Zubarev, A N

    2003-10-24

    We report high statistics measurements of inclusive charged hadron production in Au+Au and p+p collisions at sqrt[s(NN)]=200 GeV. A large, approximately constant hadron suppression is observed in central Au+Au collisions for 5energy dependence of the yields and the centrality and p(T) dependence of the suppression provide stringent constraints on theoretical models of suppression. Models incorporating initial-state gluon saturation or partonic energy loss in dense matter are largely consistent with observations. We observe no evidence of p(T)-dependent suppression, which may be expected from models incorporating jet attenuation in cold nuclear matter or scattering of fragmentation hadrons.

  19. In situ observations of the isotopic composition of methane at the Cabauw tall tower site

    NASA Astrophysics Data System (ADS)

    Röckmann, Thomas; Eyer, Simon; van der Veen, Carina; Popa, Maria E.; Tuzson, Béla; Monteil, Guillaume; Houweling, Sander; Harris, Eliza; Brunner, Dominik; Fischer, Hubertus; Zazzeri, Giulia; Lowry, David; Nisbet, Euan G.; Brand, Willi A.; Necki, Jaroslav M.; Emmenegger, Lukas; Mohn, Joachim

    2016-08-01

    High-precision analyses of the isotopic composition of methane in ambient air can potentially be used to discriminate between different source categories. Due to the complexity of isotope ratio measurements, such analyses have generally been performed in the laboratory on air samples collected in the field. This poses a limitation on the temporal resolution at which the isotopic composition can be monitored with reasonable logistical effort. Here we present the performance of a dual isotope ratio mass spectrometric system (IRMS) and a quantum cascade laser absorption spectroscopy (QCLAS)-based technique for in situ analysis of the isotopic composition of methane under field conditions. Both systems were deployed at the Cabauw Experimental Site for Atmospheric Research (CESAR) in the Netherlands and performed in situ, high-frequency (approx. hourly) measurements for a period of more than 5 months. The IRMS and QCLAS instruments were in excellent agreement with a slight systematic offset of (+0.25 ± 0.04) ‰ for δ13C and (-4.3 ± 0.4) ‰ for δD. This was corrected for, yielding a combined dataset with more than 2500 measurements of both δ13C and δD. The high-precision and high-temporal-resolution dataset not only reveals the overwhelming contribution of isotopically depleted agricultural CH4 emissions from ruminants at the Cabauw site but also allows the identification of specific events with elevated contributions from more enriched sources such as natural gas and landfills. The final dataset was compared to model calculations using the global model TM5 and the mesoscale model FLEXPART-COSMO. The results of both models agree better with the measurements when the TNO-MACC emission inventory is used in the models than when the EDGAR inventory is used. This suggests that high-resolution isotope measurements have the potential to further constrain the methane budget when they are performed at multiple sites that are representative for the entire European domain.

  20. Modulation of energy-dependent quenching of excitons in antennae of higher plants

    PubMed Central

    Avenson, Thomas J.; Cruz, Jeffrey A.; Kramer, David M.

    2004-01-01

    Energy-dependent exciton quenching, or qE, protects the higher plant photosynthetic apparatus from photodamage. Initiation of qE involves protonation of violaxanthin deepoxidase and PsbS, a component of the photosystem II antenna complex, as a result of lumen acidification driven by photosynthetic electron transfer. It has become clear that the response of qE to linear electron flow, termed “qE sensitivity,” must be modulated in response to fluctuating environmental conditions. Previously, three mechanisms have been proposed to account for qE modulation: (i) the sensitivity of qE to the lumen pH is altered; (ii) elevated cyclic electron flow around photosystem I increases proton translocation into the lumen; and (iii) lowering the conductivity of the thylakoid ATP synthase to protons (gH+) allows formation of a larger steady-state proton motive force (pmf). Kinetic analysis of the electrochromic shift of intrinsic thylakoid pigments, a linear indicator of transthylakoid electric field component, suggests that, when CO2 alone was lowered from 350 ppm to 50 ppm CO2, modulation of qE sensitivity could be explained solely by changes in conductivity. Lowering both CO2 (to 50 ppm) and O2 (to 1%) resulted in an additional increase in qE sensitivity that could not be explained by changes in conductivity or cyclic electron flow associated with photosystem I. Evidence is presented for a fourth mechanism, in which changes in qE sensitivity result from variable partitioning of proton motive force into the electric field and pH gradient components. The implications of this mechanism for the storage of proton motive force and the regulation of the light reactions are discussed. PMID:15064404

  1. SU-E-T-361: Energy Dependent Radiation/light-Field Misalignment On Truebeam Linear Accelerator

    SciTech Connect

    Sperling, N; Tanny, S; Parsai, E

    2015-06-15

    Purpose: Verifying the co-incidence of the radiation and light field is recommended by TG-142 for monthly and annual checks. On a digital accelerator, it is simple to verify that beam steering settings are consistent with accepted and commissioned values. This fact should allow for physicists to verify radiation-light-field co-incidence for a single energy and accept that Result for all energies. We present a case where the radiation isocenter deviated for a single energy without any apparent modification to the beam steering parameters. Methods: The radiation isocenter was determined using multiple Methods: Gafchromic film, a BB test, and radiation profiles measured with a diode. Light-field borders were marked on Gafchromic film and then irradiated for all photon energies. Images of acceptance films were compared with films taken four months later. A phantom with a radio-opaque BB was aligned to isocenter using the light-field and imaged using the EPID for all photon energies. An unshielded diode was aligned using the crosshairs and then beam profiles of multiple field sizes were obtained. Field centers were determined using Omni-Pro v7.4 software, and compared to similar scans taken during commissioning. Beam steering parameter files were checked against backups to determine that the steering parameters were unchanged. Results: There were no differences between the configuration files from acceptance. All three tests demonstrated that a single energy had deviated from accepted values by 0.8 mm in the inline direction. The other two energies remained consistent with previous measurements. The deviated energy was re-steered to be within our clinical tolerance. Conclusions: Our study demonstrates that radiation-light-field coincidence is an energy dependent effect for modern linacs. We recommend that radiation-light-field coincidence be verified for all energies on a monthly basis, particularly for modes used to treat small fields, as these may drift without

  2. Effect of coupled channels on the energy dependence of phenomenological optical potential parameters

    NASA Astrophysics Data System (ADS)

    Al-Rayashi, W. S.; Jaghoub, M. I.

    2016-06-01

    The phenomenological optical potential parameters are known to vary with incident energy due to sources of nonlocalities in the nucleon-nucleus elastic scattering process. Here we investigate the effect of one source, which is coupling the ground-state elastic channel to collective inelastic excitations on the energy dependence of the optical potential parameters. For incident energies in the range 10-70 MeV, we considered elastic and inelastic nucleon scattering from light, medium, and heavy nuclei ranging from 6Li to 208Pb. The potential parameters were first determined by fitting the elastic angular distributions only. Then we included coupling to collective excitation channels and determined the potential parameters that reproduced the elastic and inelastic angular distribution data simultaneously. Our results show that coupling to inelastic excitations reduces the energy variations of the potential parameters compared to that of the elastic scattering case. In particular, the our best fit values for the real part of the spin-orbit term are highly stable as a function of energy. The values of the surface imaginary term are not only more stable but are also reduced compared to the elastic case. The reduction is a direct consequence of the channel coupling accounting explicitly for part of the flux removed from the elastic channel. In the fitting process we also searched for the best fit values of the deformation parameters. Our values compare well with the corresponding ones obtained in previous works. Finally, we used our best fit values for the potential and deformation parameters to theoretically predict the total elastic, total cross section, and polarization data. The predicted values are in very good agreement with the experimental data.

  3. Experimental Observations of a Stitched Composite with a Notch Subjected to Combined Bending and Tension Loading

    NASA Technical Reports Server (NTRS)

    Palmer, Susan O.; Nettles, Alan T.; Poe, C. C.

    1998-01-01

    A series of tests was conducted to support development of an analytical model for predicting the failure strains of stitched warp-knit carbon/epoxy composite materials with through-thicknesss damage in the form of a crack-like notch. Measurements of strain near notch tips, crack opening displacement (COD), and applied load were monitored in all tests. The out-of-plane displacement at the center of the notch was also measured when the specimen was subjected to bending. Three types of loading were applied: pure bending, pure tension, and combined bending and tension.

  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.

  5. 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

  6. 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.

  7. Collocated observations of cloud condensation nuclei, particle size distributions, and chemical composition.

    PubMed

    Schmale, Julia; Henning, Silvia; Henzing, Bas; Keskinen, Helmi; Sellegri, Karine; Ovadnevaite, Jurgita; Bougiatioti, Aikaterini; Kalivitis, Nikos; Stavroulas, Iasonas; Jefferson, Anne; Park, Minsu; Schlag, Patrick; Kristensson, Adam; Iwamoto, Yoko; Pringle, Kirsty; Reddington, Carly; Aalto, Pasi; Äijälä, Mikko; Baltensperger, Urs; Bialek, Jakub; Birmili, Wolfram; Bukowiecki, Nicolas; Ehn, Mikael; Fjæraa, Ann Mari; Fiebig, Markus; Frank, Göran; Fröhlich, Roman; Frumau, Arnoud; Furuya, Masaki; Hammer, Emanuel; Heikkinen, Liine; Herrmann, Erik; Holzinger, Rupert; Hyono, Hiroyuki; Kanakidou, Maria; Kiendler-Scharr, Astrid; Kinouchi, Kento; Kos, Gerard; Kulmala, Markku; Mihalopoulos, Nikolaos; Motos, Ghislain; Nenes, Athanasios; O'Dowd, Colin; Paramonov, Mikhail; Petäjä, Tuukka; Picard, David; Poulain, Laurent; Prévôt, André Stephan Henry; Slowik, Jay; Sonntag, Andre; Swietlicki, Erik; Svenningsson, Birgitta; Tsurumaru, Hiroshi; Wiedensohler, Alfred; Wittbom, Cerina; Ogren, John A; Matsuki, Atsushi; Yum, Seong Soo; Myhre, Cathrine Lund; Carslaw, Ken; Stratmann, Frank; Gysel, Martin

    2017-03-14

    Cloud condensation nuclei (CCN) number concentrations alongside with submicrometer particle number size distributions and particle chemical composition have been measured at atmospheric observatories of the Aerosols, Clouds, and Trace gases Research InfraStructure (ACTRIS) as well as other international sites over multiple years. Here, harmonized data records from 11 observatories are summarized, spanning 98,677 instrument hours for CCN data, 157,880 for particle number size distributions, and 70,817 for chemical composition data. The observatories represent nine different environments, e.g., Arctic, Atlantic, Pacific and Mediterranean maritime, boreal forest, or high alpine atmospheric conditions. This is a unique collection of aerosol particle properties most relevant for studying aerosol-cloud interactions which constitute the largest uncertainty in anthropogenic radiative forcing of the climate. The dataset is appropriate for comprehensive aerosol characterization (e.g., closure studies of CCN), model-measurement intercomparison and satellite retrieval method evaluation, among others. Data have been acquired and processed following international recommendations for quality assurance and have undergone multiple stages of quality assessment.

  8. Ionosphere of venus: first observations of day-night variations of the ion composition.

    PubMed

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

    1979-07-06

    The Bennett radio-frequency ion mass spectrometer on the Pioneer Venus orbiter is returning the first direct composition evidence of the processes responsible for the formation and maintenance of the nightside ionosphere. Early results from predusk through the nightside in the solar zenith angle range 63 degrees (dusk) to 120 degrees (dawn) reveal that, as on the dayside, the lower nightside ionosphere consists of F(1)and F(2) layers dominated by O(2)(+) and O(+), respectively. Also like the dayside, the nightside composition includes distributions of NO(+), C(+), N(+), H(+), He(+), CO(2)(+), and 28(+) (a combination of CO(+) and N(2)(+)). The surprising abundance of the nightside ionosphere appears to be maintained by the transport of O(+) from the dayside, leading also to the formation of O(2)(+) through charge exchange with CO(2). Above the exobase, the upper nightside ionosphere exhibits dramatic variability in apparent response to variations in the solar wind and interplanetary magnetic field, with the ionopause extending to several thousand kilometers on one orbit, followed by the complete rertnoval of thermal ions to altitudes below 200 kilometers on the succeeding orbit, 24 hours later. In the upper ionosphere, considerable structure is evident in many of the nightside ion profiles. Also evident are horizontal ion drifts with velocities up to the order of 1 kilometer per second. Whereas the duskside ionopause is dominated by O(+) H(+) dominates the topside on the dawnside of the antisolar point, indicating two separate regions for ion depletion in the magnetic tail regions.

  9. Collocated observations of cloud condensation nuclei, particle size distributions, and chemical composition

    PubMed Central

    Schmale, Julia; Henning, Silvia; Henzing, Bas; Keskinen, Helmi; Sellegri, Karine; Ovadnevaite, Jurgita; Bougiatioti, Aikaterini; Kalivitis, Nikos; Stavroulas, Iasonas; Jefferson, Anne; Park, Minsu; Schlag, Patrick; Kristensson, Adam; Iwamoto, Yoko; Pringle, Kirsty; Reddington, Carly; Aalto, Pasi; Äijälä, Mikko; Baltensperger, Urs; Bialek, Jakub; Birmili, Wolfram; Bukowiecki, Nicolas; Ehn, Mikael; Fjæraa, Ann Mari; Fiebig, Markus; Frank, Göran; Fröhlich, Roman; Frumau, Arnoud; Furuya, Masaki; Hammer, Emanuel; Heikkinen, Liine; Herrmann, Erik; Holzinger, Rupert; Hyono, Hiroyuki; Kanakidou, Maria; Kiendler-Scharr, Astrid; Kinouchi, Kento; Kos, Gerard; Kulmala, Markku; Mihalopoulos, Nikolaos; Motos, Ghislain; Nenes, Athanasios; O’Dowd, Colin; Paramonov, Mikhail; Petäjä, Tuukka; Picard, David; Poulain, Laurent; Prévôt, André Stephan Henry; Slowik, Jay; Sonntag, Andre; Swietlicki, Erik; Svenningsson, Birgitta; Tsurumaru, Hiroshi; Wiedensohler, Alfred; Wittbom, Cerina; Ogren, John A.; Matsuki, Atsushi; Yum, Seong Soo; Myhre, Cathrine Lund; Carslaw, Ken; Stratmann, Frank; Gysel, Martin

    2017-01-01

    Cloud condensation nuclei (CCN) number concentrations alongside with submicrometer particle number size distributions and particle chemical composition have been measured at atmospheric observatories of the Aerosols, Clouds, and Trace gases Research InfraStructure (ACTRIS) as well as other international sites over multiple years. Here, harmonized data records from 11 observatories are summarized, spanning 98,677 instrument hours for CCN data, 157,880 for particle number size distributions, and 70,817 for chemical composition data. The observatories represent nine different environments, e.g., Arctic, Atlantic, Pacific and Mediterranean maritime, boreal forest, or high alpine atmospheric conditions. This is a unique collection of aerosol particle properties most relevant for studying aerosol-cloud interactions which constitute the largest uncertainty in anthropogenic radiative forcing of the climate. The dataset is appropriate for comprehensive aerosol characterization (e.g., closure studies of CCN), model-measurement intercomparison and satellite retrieval method evaluation, among others. Data have been acquired and processed following international recommendations for quality assurance and have undergone multiple stages of quality assessment. PMID:28291234

  10. 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

  11. 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.

  12. Neutron transfer versus inelastic surface vibrations in the enhancement of sub-barrier fusion excitation function data and the energy dependent Woods-Saxon potential

    NASA Astrophysics Data System (ADS)

    Singh Gautam, Manjeet

    2015-02-01

    This work deeply analyzed the relative importance of the neutron transfer channels and inelastic surface vibrations of colliding nuclei in the sub-barrier fusion enhancement of various heavy ion systems using an energy dependent Woods-Saxon potential (EDWSP) model in conjunction with a one-dimensional Wong formula and the coupled channel formulation using the code CCFULL. The multi-phonon vibrational states of colliding nuclei and the nucleon transfer channels are found to be dominant internal degrees of freedom. The coupling between the relative motion of reactants and these relevant channels produces anomalously large sub-barrier fusion enhancement over the expectations of the one-dimensional barrier penetration model. In some cases, the influence of neutron transfer dominates over the couplings to low lying surface vibrational states of collision partners. Furthermore, the effects of coupling to inelastic surface excitations and the impact of neutron transfer channels with positive ground state Q-values are imitated due to energy dependence in the Woods-Saxon potential. In the EDWSP model calculations, a wide range for the diffuseness parameter, which is much larger than the value extracted from the elastic scattering data, is needed to account for the observed fusion enhancement in the close vicinity of the Coulomb barrier.

  13. 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.

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

    NASA Technical Reports Server (NTRS)

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

    2016-01-01

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

  15. High Pressure Crystallization of Mafic Magma: Field Observations, Compositional Measurements and Computer Modeling

    NASA Astrophysics Data System (ADS)

    Tracy, R. J.

    2009-05-01

    The Cortlandt Complex is a small early Silurian composite, mafic to ultramafic, anorogenic deep crustal pluton about 60 km N of New York City in which most rocks in the six mapped plutonic phases have resulted from either fractionation or contamination or both. Bender et al (AJS-1984) estimated Cortlandt parental composition as an alkalic gabbro based on the nature of early plutons. The youngest and easternmost pluton consists largely of concentrically layered pyroxenites and olivine pyroxenites (with subequal modal proportions of opx and cpx, and only minor ol) and it appears to have had a different parental magma. Samples collected through a series of layers reflecting a few hundred meters of stratigraphy in layered pyroxenites indicate wide variation in F/FM (0.18 to 0.3) and both Al and Ti contents of pyroxenes are unusually high (cpx - Al2O3 from 6-7 wt percent and TiO2 from 1.0 - 1.5 wt percent; opx - Al2O3 from 3.8 - 5.7 wt percent and TiO2 from 0.2 to 0.7 wt percent). All pyroxenes show significant exsolution of ilm lamellae. Crystallization pressure has been well constrained by thermobarometry of metapelites in the thermal aureole at roughly 0.8 GPa, making this a very unusual example of very high P cumulate formation. Several magma compositions were tested as suitable parents by running computer simulations using MELTS (Ghiorso and Sack, 1995, CMP; Asimow and Ghiorso, 1998, Am. Min.). These MELTS runs quickly eliminated the proposed alkalic gabbro parent - it did not crystallize opx at any P. In this preliminary modeling, the most suitable parental magma for the cumulates was a picritic Karoo basalt (SiO2 - 46.9, TiO2 - 1.6, Al2O3 - 9.3, FeO - 12.2, MgO - 15.9, CaO - 9.1; Na2O - 1.3, K2O - 0.6, P2O5 - 0.2). MELTS runs at 8 kbar and FMQ showed a close approximation to both mineral proportions and mineral chemistry of the Cortlandt samples. The initial liquidus phase was opx at 1421C, ol at 1407C (L 4.4percent crystallized), spl at 1301C (L 19.7 percent

  16. 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.…

  17. 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.

  18. 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.

  19. 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.

  20. 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

    2008-07-04

    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.

  1. Direct Observation of Fracture of Cas-Glass/SiC Composites and Processing of Toughened Alumina

    DTIC Science & Technology

    1992-09-01

    to the load-displacement behaviour include indirect techniques such as acoustic emission and edge replication microscopy ( Zawada et at, 1991; Harris...18b). Zawada et aL (1991) also observed that 900 ply cracks precede 00 cracks in tests on the same cross-ply material with unnotched specimens; Pryce...have been some loss of stiffness. Similar behaviour has been found in fatigue with unnotched specimens of this material by Zawada et aL (1991). - 58

  2. Aerosol Observability and Data Assimilation Investigations in Support of Atmospheric Composition Forecasts

    DTIC Science & Technology

    2013-09-30

    Assimilation-Aerosol Optical Depth (NAVDAS- AOD ) framework. This work also led to the development of the world’s first quasi-operational global multi...satellite and in situ observations including their flow dependant correlation lengths for use in NAVDAS- AOD : The optimal mix of meteorological and...project with Dr. Hansen. Hence, in house knowledge already exists to expedite this process . Included in this budget is additional travel money so that

  3. Aerosol Observability and Data Assimilation Investigations in Support of Atmospheric Composition Forecasts

    DTIC Science & Technology

    2012-09-30

    aerosol model demands for such applications as joint surface-atmosphere retrievals, directed energy (DE), and intelligence, surveillance, and...C. Schmidt, J. I Miettinen, L. Giglio, (2012), Different views of fire activity over Indonesia and Malaysia from polar and geostationary...Greece, 25-29 June, 2012. Hyer, E. J., J. S. Reid, E. M. Prins, J. Hoffman, C. C. Schmidt, L. Giglio, D. A. Peterson (2011) Biomass burning observations

  4. 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).

  5. 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.

  6. 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

  7. 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.

  8. 3D multi-observable probabilistic inversion for the compositional and thermal structure of the lithosphere and sublithospheric upper mantle

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    High-resolution imaging and characterization of the thermal and compositional structure of the lithospheric and sublithospheric upper mantle are the basis for understanding the formation and evolution of the lithosphere and the interaction between the crust-mantle and lithosphere-asthenosphere systems. Unfortunately, such imaging and characterization using available geophysical-geochemical methods still present unsolved and technically challenging problems. In this contribution we present a new full-3D multi-observable inversion method particularly designed for high-resolution (regional) thermal and compositional mapping of the lithosphere and sublithospheric upper mantle. Ambient noise tomography, multiple plane wave earthquake tomography, magnetotelluric, thermal, thermodynamic, and potential field modelling are all combined in a single thermodynamic-geophysical framework and appraised within a general probabilistic (Bayesian) formulation. This circumvents the problems of strong non-linearity involved in traditional inversions, provides highly refined seismic information, minimizes the problem of trade-off between temperature and composition in wave speeds, offers critical insights into incompatibilities between traditional stand-alone methods, and takes advantage of a priori local geochemical information. Both synthetic models and preliminary results in real-case examples will be used to discuss the benefits, robustness, and limitations of this method.

  9. 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.

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

    NASA Astrophysics Data System (ADS)

    Grimes, Glenn C.

    1994-07-01

    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.

  11. 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.

  12. Is the Z0 observed in pp collisions a composite object?

    NASA Astrophysics Data System (ADS)

    Renard, F. M.

    1983-12-01

    If the Z0 boson is made of colored subconstituents it can be produced in pp (and pp) collisions through the subprocess gluon + gluon --> Z0 + gluon. The rate is estimated from the Z0 - γ mixing parameter and found comparable to that of the Drell-Yan process. Events with a large pTZ0 and a large pT balancing gluon should be observed at the pp collider. Address after October 1, 1983: Dêpartment de Physique Mathématique, USTL, 34060 Montpellier Cedex, France.

  13. 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

  14. Composition of Pickup Ions at Titan Observed by the Cassini Plasma Spectrometer

    NASA Technical Reports Server (NTRS)

    Hartle, R.; Sittler, E.; Burger, M.; Shappirio, M.; Johnson, R.; Smith, H.; Reisenfeld, D.; Szego, K.; Bertucci, C.; Neubauer, F.; Bolton, S.; Young, D.

    2006-01-01

    Pickup ions have been observed in Saturn's rotating magnetosphere near Titan by the Cassini Plasma Spectrometer (CAPS) instrument during the Cassini orbiter's recent flybys of the moon. A preliminary analysis of the CAPS Time of Flight (TOF) spectra of the pickup ions observed during the TA flyby indicated the presence of H(+), H2(+), N(+)/CH2(+), CH4(+), and N2(+). These ions slow down Saturn's magnetospheric plasma beyond Titan's ionosphere through mass loading. Because of its relatively high mass and high concentration, CH4(+) is the dominant mass loading ion. The other ions make negligible contributions to the mass loading process except for N2(+) just above the ionopause, where its concentration becomes important. With the exception of CH2(+), the pickup ion sources are the neutral exosphere constituents H, H2, N, CH4, and N2, where CH2 is a fragment of the parents CH4 and CH4(+). A more detailed analysis of CAPS TOF spectra and empirical cracking patterns is carried out to determine the relative concentrations of N(+) and CH2(+). Although, the 28 amu ion was identified as N2(+), consistent with the dominance of its neutral source, N2, just above the ionopause, the ionospheric ion HCNH(+) may also be present. The possible leakage of this and other ionospheric ions such as CH5(+) into the pickup ion /mass loading region is also examined by further analysis of the corresponding TOF spectra.

  15. 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

  16. 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.

  17. A Biaxial-Bending Test to Observe the Growth of Interacting Delaminations in a Composite Laminate Plate

    NASA Technical Reports Server (NTRS)

    McElroy, Mark; Jackson, Wade; Pankow, Mark

    2016-01-01

    It is not easy to isolate the damage mechanisms associated with low-velocity impact in composites using traditional experiments. In this work, a new experiment is presented with the goal of generating data representative of progressive damage processes caused by low-velocity impact in composite materials. Carbon fiber reinforced polymer test specimens were indented quasi-statically such that a biaxial-bending state of deformation was achieved. As a result, a three-dimensional damage process, involving delamination and delamination-migration, was observed and documented using ultrasonic and x-ray computed tomography. Results from two different layups are presented in this paper. Delaminations occurred at up to three different interfaces and interacted with one another via transverse matrix cracks. Although this damage pattern is much less complex than that of low-velocity impact on a plate, it is more complex than that of a standard delamination coupon test and provides a way to generate delamination, matrix cracking, and delamination-migration in a controlled manner. By limiting the damage process in the experiment to three delaminations, the same damage mechanisms seen during impact could be observed but in a simplified manner. This type of data is useful in stages of model development and validation when the model is capable of simulating simple tests, but not yet capable of simulating more complex and realistic damage scenarios.

  18. Direct observations of the role of solution composition in magnesite dissolution

    NASA Astrophysics Data System (ADS)

    King, H. E.; Putnis, C. V.

    2012-04-01

    Magnesite, MgCO3, occurs in association with the alteration of ultramafic rocks and serpentine during metamorphic and metasomatic events. Its formation from the carbonation of olivine is an indication of natural CO2 sequestration. Both magnesite dissolution and precipitation are controlled by the strongly hydrated nature of the Mg2+ ion in solution. Flow-through experiments have shown that increased dissolution results from an increase in ionic strength of the solution (Pokrovsky and Schott, 1999). To test whether this observation is related to changes in Mg hydration, we have compared the dissolution of the {1014} magnesite surface in solutions of different electrolytes (NaCl, NaNO3 and Na2SO4) using atomic force microscopy (AFM). As the dissolution of magnesite is slow at ambient conditions, experimental solutions (water, 10, 100 and 500 mM) were acidified (pH 2). In all electrolyte solutions, dissolution of the magnesite surface began by the nucleation of randomly spaced etch pits followed by the sudden nucleation of many pits across the entire surface. Coalescence of etch pits produced islands of remnant surface which then dissolved until a single layer was removed and a new flat surface generated. The process was then repeated via the further nucleation of random etch pits one unit cell deep ( 0.3 nm). Dissolution rates were obtained from the frequency of this dissolution cycle using measurements of surface roughness and etch pit spreading rates. The reactivity of magnesite in the presence of added ions varied in the order Na2SO4 < NaCl < NaNO3. Increased dissolution rates in the presence of NO3 compared to Cl is consistent with changes in Mg hydration (Ruiz-Agudo et al., 2010). However, although the ionic strength of the equivalent Na2SO4 concentrations was higher than that of NaCl (expected to increase magnesite dissolution), we observed a decrease in dissolution. The effect of sulfate is most likely dependent on the formation of Mg-SO4 contact ion pairs

  19. The surface composition and temperature of asteroid 21 Lutetia as observed by Rosetta/VIRTIS.

    PubMed

    Coradini, A; Capaccioni, F; Erard, S; Arnold, G; De Sanctis, M C; Filacchione, G; Tosi, F; Barucci, M A; Capria, M T; Ammannito, E; Grassi, D; Piccioni, G; Giuppi, S; Bellucci, G; Benkhoff, J; Bibring, J P; Blanco, A; Blecka, M; Bockelee-Morvan, D; Carraro, F; Carlson, R; Carsenty, U; Cerroni, P; Colangeli, L; Combes, M; Combi, M; Crovisier, J; Drossart, P; Encrenaz, E T; Federico, C; Fink, U; Fonti, S; Giacomini, L; Ip, W H; Jaumann, R; Kuehrt, E; Langevin, Y; Magni, G; McCord, T; Mennella, V; Mottola, S; Neukum, G; Orofino, V; Palumbo, P; Schade, U; Schmitt, B; Taylor, F; Tiphene, D; Tozzi, G

    2011-10-28

    The Visible, InfraRed, and Thermal Imaging Spectrometer (VIRTIS) on Rosetta obtained hyperspectral images, spectral reflectance maps, and temperature maps of the asteroid 21 Lutetia. No absorption features, of either silicates or hydrated minerals, have been detected across the observed area in the spectral range from 0.4 to 3.5 micrometers. The surface temperature reaches a maximum value of 245 kelvin and correlates well with topographic features. The thermal inertia is in the range from 20 to 30 joules meter(-2) kelvin(-1) second(-0.5), comparable to a lunarlike powdery regolith. Spectral signatures of surface alteration, resulting from space weathering, seem to be missing. Lutetia is likely a remnant of the primordial planetesimal population, unaltered by differentiation processes and composed of chondritic materials of enstatitic or carbonaceous origin, dominated by iron-poor minerals that have not suffered aqueous alteration.

  20. 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.

  1. Titania and Oberon: Surface Composition from New Near-Infrared Observations and Reflectance Models

    NASA Technical Reports Server (NTRS)

    Roush, Ted L.; Cruikshank, D. P.; Owen, T. C.; Geballe, T. R.; Benedix, G. K.; deBergh, C.; Noll, K. S.; Khare, B.; DeVincenzi, Donald (Technical Monitor)

    1998-01-01

    Here we report the combination of new near-ir spectra (1.45-2.48 micrometers), of Titania and Oberon obtained in September 1995 at a resolving power of approx. 800, with older near-ir observations (0.5- 1.44 micrometers), and recent UV (0.22-0.48 micrometers) observations obtained with HST. Previous interpretations suggest these surfaces are chiefly composed of water ice and varying amounts of spectrally neutral material. The new near-ir data provide the opportunity to search for absorption bands that could be attributable to surface materials other than water ice and because the combined spectra include such a broad wavelength region, to undertake improved models of water and neutral components on the surface. The calculated near-ir geometric albedos clearly exhibit three broad spectral features. Two (1.52- & 2.05 micrometer) have previously been used to demonstrate the presence of water ice on these satellites. The third (approx. 1.65 micrometer), suggests the presence of hexagonal water ice at low temperatures, and may provide a mechanism of estimating the surface temperature. There is no spectral evidence for ices of CO2, CO, NH3 or CH4. At UV wavelengths there is a broad absorption near 0.27-0.28 micrometer previously attributed to OH formed by magnetospheric-surface interactions and retained at the low surface temperatures of these satellites. Surface components used in a Hapke scattering models include values for a combination of irradiated water ice in the UV and hexagonal water ice at 100k in the near-ir (IR), amorphous carbon (AC), and tholins (T) (produced from gas and solid). Results of these models suggest the surfaces of Titania/Oberon are composed of IW (-77/52%) with AC the next most abundant component (approx. 19/52%) and finally T (approx. 4/7%).

  2. Biophysical and Pharmacological Characterization of Energy-Dependent Efflux of Sb in Laboratory-Selected Resistant Strains of Leishmania (Viannia) Subgenus

    PubMed Central

    dos Reis, Priscila G.; do Monte-Neto, Rubens L.; Melo, Maria N.; Frézard, Frédéric

    2017-01-01

    The growing resistance of leishmaniasis to first-line drugs like antimonials in some regions limits the control of this parasitic disease. The precise mechanisms involved in Leishmania antimony resistance are still subject to debate. The reduction of intracellular SbIII accumulation is a common change observed in both laboratory-selected and field isolated resistant Leishmania strains, but the exact transport pathways involved in antimony resistance have not yet been elucidated. In order to functionally characterize the antimony transport routes responsible for resistance, we performed systematic transport studies of SbIII in wild-type and resistant strains of L. (Viannia) guyanensis and L. (V.) braziliensis. Those include influx and efflux assays and the influence of ABC transporters and metabolism inhibitors: prochlorperazine, probenecid, verapamil, BSO, and sodium azide. The mRNA levels of genes associated with antimony resistance (MRPA, GSH1, ODC, AQP1, ABCI4, and ARM58) were also investigated in addition to intracellular thiol levels. A strong reduction of Sb influx was observed in L. guyanensis resistant mutant (LgSbR), but not in L. braziliensis (LbSbR). Both mutants showed increased energy-dependent efflux of SbIII, when compared to their respective parental strains. In LgSbR, BSO and prochlorperazine inhibited antimony efflux and resistance was associated with increased MRPA and GSH1 mRNA levels, while in LbSbR antimony efflux was inhibited by probenicid and prochlorperazine in absence of resistance-associated gene modulation. Intracellular thiol levels were increased in both Sb-resistant mutants. An energy-dependent SbIII efflux pathway sensitive to prochlorperazine was clearly evidenced in both Sb-resistant mutants. In conclusion, the present study allowed the biophysical and pharmacological characterization of energy-dependent Sb efflux pathway apparently independent of MRPA, ABCI4, and ARM58 upregulation, in Leishmania (Vianna) mutant selected in vitro

  3. Energy dependent sticking coefficients of trimethylamine on Si(001)-Influence of the datively bonded intermediate state on the adsorption dynamics

    NASA Astrophysics Data System (ADS)

    Lipponer, M. A.; Reutzel, M.; Dürr, M.; Höfer, U.

    2016-11-01

    The adsorption dynamics of the datively bonded trimethylamine (TMA) on Si(001) was investigated by means of molecular beam techniques. The initial sticking probability s0 of TMA on Si(001) was measured as a function of kinetic energy at two different surface temperatures (230 and 550 K). At given surface temperature, s0 was found to decrease with increasing kinetic energy (0.1 to 0.6 eV) indicating a non-activated reaction channel. At increased surface temperature, s0 is reduced due to the onset of desorption into the gas phase. The energy dependence of s0 is compared to the results for the adsorption of tetrahydrofuran (THF) on Si(001), which reacts via a datively bonded intermediate into a covalently bound final state. As s0 follows the same energy dependence both for TMA and THF, the datively bonded intermediate state is concluded to dominate the reaction dynamics in the latter case as well.

  4. Inferring the Observed PSC Composition Using the Improved Limb Atmospheric Spectrometer (ILAS) Data Along With Trajectory Analysis

    NASA Astrophysics Data System (ADS)

    Saitoh, N.; Hayashida, S.; Sasano, Y.

    2001-12-01

    The Improved Limb Atmospheric Spectrometer (ILAS) captured many polar stratospheric cloud (PSC) events in the Northern Hemisphere during the winter and early spring of 1997. We identified about 250 events in 65 profiles as PSCs in the Arctic. Preliminary analysis made it clear that the ILAS also observed many PSC events during the early winter of 1997 in the Southern Hemisphere. The ILAS aerosol extinction coefficient and nitric acid data were compared with the theoretically predicted values for supercooled ternary solution (STS), nitric acid dihydrate (NAD), and nitric acid trihydrate (NAT) particles at thermodynamic equilibrium to infer the chemical composition of the observed PSC particles. In mid-January of 1997, both the extinction coefficient and nitric acid values of some of the observed PSC events showed better agreement with the theoretical values for STS than with those of NAT or NAD. Although a few PSCs were observed in March, most of the PSCs observed late in the PSC season had features of nitric-acid-containing hydrates. An intensive analysis of the temperature histories suggested that most of the STS particles observed in January had experienced the thermal conditions necessary for the formation of liquid particles. The nitric-acid-containing solid PSC events observed in early March experienced temperatures below TNAT for more than several days, and sometimes fell below Tice during the 20-day period. They had not passed over typical mountainous area before their measurements, so the formation mechanisms of these solid particles should be explained from their synoptic scale temperature histories, without considering lee waves. They maintained relatively high nitric acid hydrate saturation ratios along their trajectory, which suggests their homogeneous nucleation.

  5. The 67P nucleus composition and temporal variations observed by the OSIRIS cameras onboard Rosetta

    NASA Astrophysics Data System (ADS)

    Fornasier, Sonia; Barucci, Maria Antonietta; Feller, Clement; Deshapriya, Prasanna J. D.; Pommerol, Antoine; Lara, Luisa; Oklay, Nilda; A'Hearn, Mike; Davidsson, Bjorn; Perna, Davide; Sierks, Holger

    2015-11-01

    Since August 2014, the comet 67P/Churyumov-Gerasimenko has been mapped by the NAC and WAC cameras of the OSIRIS imaging system in the 250-1000 nm wavelength range. OSIRIS got the most detailed maps at the highest spatial resolution of a comet nucleus surface. Here we report on the colors and spectrophotometry of the whole 67P nucleus from images acquired since the first Rosetta bound orbits in August 2014 up to the comet perihelion passage. Globally, the nucleus shows a red spectral behavior and it has spectrophotometric properties similar to those of bare cometary nuclei, of primitive D-type asteroids such us Jupiter Trojans, and of the moderately red Transneptunians. No clear absorption bands have been identified yet in the UV-VIS-NIR range, except for a potential absorption centered at 290 nm, possibly due to SO2 ice. The nucleus shows an important phase reddening, with disk-averaged spectral slopes increasing from 11%/(100 nm) to 16%/(100 nm) in the 1.3-54° phase angle range. On the basis of the spectral slope, we identified three different groups of regions, characterized by a low, medium, and high spectral slope, respectively. The three groups are distributed everywhere on the nucleus, with no evident distinction between the two lobes of the comet. The comet southern hemisphere, that has been observed by Rosetta since April 2015, shows a lack of spectrally red regions associated to the absence of wide spread smooth or dust covered terrains. Several local bright and spectrally blue patches have been identified on the nucleus and attributed to exposed water ice on the surface. In particular we observed big (> 1500 m2) bright ice rich areas in the southern hemisphere which completely sublimated in a few weeks. We see evidence of very bright patches in the NUV-blue region close to the morning shadows that are compatible with the presence of frosts/ices. These patches disappear when fully illuminated by the Sun indicating that important processes of sublimation

  6. Energy dependence and temporal evolution of the /sup 3/He//sup 4/He ratios in heavy-ion-rich energetic particle events

    SciTech Connect

    Moebius, E.; Hovestadt, D.; Klecker, B.; Gloeckler, G.

    1980-06-01

    The energy dependence of the /sup 3/He//sup 4/He ratio between 0.44 and 4.1 MeV per nucleon has been studied for six heavy-ion--rich events observed in 1974 and 1976 using the low-energy dE/dx versus E Ultralow-Energy Particle telescope (ULET) on IMP 8. We find that all selected heavy-ion--rich events are also enriched in /sup 3/He, that the /sup 3/He//sup 4/He He ratio decreases with decreasing energies, and that a rapid temporal evolution of the /sup 3/He//sup 4/He and the Fe/(H+He) ratios is strongly correlated during one event with the maximum value at the onset. These results are discussed in terms of a model which is based on preferential injection of /sup 3/He and Fe resulting from turbulent ion heating and subsequent Fermi acceleration.

  7. Energy dependence of the optical potentials for the 9Be +208Pb and 9Be +209Bi systems at near-Coulomb-barrier energies

    NASA Astrophysics Data System (ADS)

    Gómez Camacho, A.; Yu, N.; Zhang, H. Q.; Gomes, P. R. S.; Jia, H. M.; Lubian, J.; Lin, C. J.

    2015-04-01

    We analyze the energy dependence of the interacting optical potential, at near barrier energies, for two systems involving the weakly bound projectile 9Be and the heavy 208Pb and 209Bi targets, by the simultaneous fit of elastic scattering angular distributions and fusion excitation functions. The approach used consists of dividing the optical potential into two parts. A short-range potential VF+i WF that is responsible for fusion, and a superficial potential VDR+i WDR for direct reactions. It is found, for both systems studied, that the fusion imaginary potential WF presents the usual threshold anomaly (TA) observed in tightly bound systems, whereas the direct reaction imaginary potential WDR shows a breakup threshold anomaly (BTA) behavior. Both potentials satisfy the dispersion relation. The direct reaction polarization potential predominates over the fusion potential and so a net overall behavior is found to follow the BTA phenomenon.

  8. Impairment of Energy-Dependent Processes in the Muscle Tissue as a Pathogenetic Mechanism of Statin-Induced Myopathy.

    PubMed

    Mikashinovich, Z I; Belousova, E S; Sarkisyan, O G

    2017-02-01

    Administration of simvastatin was followed by a decrease in activities of superoxide dismutase and cytochrome oxidase in rat mitochondria, which attested to dysfunction of the respiratory chain. The decrease in total ATPase and Ca(2+)-ATPase activities in muscle tissue homogenates reflected impaired transport of active cations essential for muscle contraction. We conclude that abnormal relationships in the system of energy synthetic and energy-dependent processes in myocytes serve as the molecular basis for the formation of statin-induced degenerative changes.

  9. 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.

  10. Energy dependent dynamics of keV to MeV electrons in the inner zone, outer zone, and slot regions

    NASA Astrophysics Data System (ADS)

    Reeves, G. D.; Friedel, R. H.; Larsen, B.; Skoug, R. M.; Funsten, H. O.; Claudepierre, S. G.; Fennell, J. F.; Turner, D. L.; Denton, M.; Spence, H. E.; Blake, J. B.; Baker, D. N.

    2015-12-01

    We present observations that illustrate the energy-dependence and L-shell dependence of radiation belt dynamics. We survey events in 2013 and analyze individual events in more detail. The survey data show: (a) Lower-energy electrons are enhanced more often than higher energies. (b) Events that fill the slot region are more common at lower energies. (c) Enhancements of electrons in the inner zone are more common at lower energies. And (d) even when events do not fully fill the slot region, enhancements at lower-energies tend to extend to lower L-shells than higher energies. The outer zone, inner zone, and slot region all occupy regions of space that are strongly energy dependent. During enhancement events the outer zone extends to lower L-shells at lower energies and higher L-shells at higher energies. The inner zone shows the opposite with an outer boundary at higher L-shells for lower energies. Both boundaries are nearly straight in log(energy) vs. L-shell space. At energies below a few hundred keV radiation belt electron penetration through the slot region into the inner zone is commonplace but the number and frequency of "slot filling" events decreases with increasing energy. The inner zone is enhanced only at energies that penetrate through the slot. Analysis shows that at least three processes may determine which electrons penetrate into the slot and inner zone: (1) enhanced convective electric fields at low L-shells, (2) impulsive, substorm-associated injections at low L-shells, and (3) slower radial diffusion and interaction with plasmaspheric hiss. These new observations challenge some of our long-held pictures of what the radiation belts look like and how they behave.

  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. 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.

  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.

  14. The temperature and ion energy dependence of deuterium retention in lithium films

    NASA Astrophysics Data System (ADS)

    Buzi, Luxherta; Koel, Bruce E.; Skinner, Charles H.

    2016-10-01

    Lithium conditioning of plasma facing components in magnetic fusion devices has improved plasma performance and lowered hydrogen recycling. For applications of lithium in future high heat flux and long pulse duration machines it is important to understand and parameterize deuterium retention in lithium. This work presents surface science studies of deuterium retention in lithium films as a function of surface temperature, incident deuterium ion energy and flux. Initial experiments are performed on thin (3-30 ML) lithium films deposited on a single crystal molybdenum substrate to avoid effects due to grain boundaries, intrinsic defects and impurities. A monoenergetic and mass-filtered deuterium ion beam was generated in a differentially pumped Colutron ion gun. Auger electron spectroscopy and X-ray photoelectron spectroscopy were used to identify the elemental composition and temperature programmed desorption was used to measure the deuterium retention under the different conditions. Support was provided through DOE Contract Number DE-AC02-09CH11466.

  15. Observations of accumulation mode aerosol composition and soot carbon concentrations by means of a high-temperature volatility technique

    NASA Astrophysics Data System (ADS)

    Smith, Michael H.; O'Dowd, Colin D.

    1996-08-01

    A high-temperature volatility system has been deployed for the measurement of the composition and concentration of the accumulation mode aerosol (0.05 μm < r < 1 μm) within the atmospheric boundary layer. This instrumentation comprises a volatility system based around a Particle Measuring Systems ASASP-X optical particle counter, which was operated together with an aethalometer for the direct observation of soot carbon concentrations. By cycling the heater tube through a range of temperatures from near ambient to over 1000°C, size-differentiated information upon aerosol composition may be obtained. Furthermore, by careful selection of analysis temperatures, discrimination is possible between elemental carbon and the more volatile fractions of the soot carbon aerosol. Observations made over the North Sea near the Dutch coast and in the central United Kingdom are presented for differing environmental conditions with soot carbon concentrations ranging from about 100 to over 6000 ng m-3. For polluted conditions over the North Sea the volatility technique clearly showed the dominance of soot carbon particles over other aerosol components with a narrow carbon particle distribution of mode radius around 0.06 μm accounting for about 80% of all particles with radii below 0.1 μm. Under polluted conditions, only about 25% of the total soot carbon aerosol comprised elemental carbon (with the remainder consisting of more volatile material), whereas this proportion rose to around 50% in the lower carbon loadings found in a cleaner maritime air mass. The use of soot carbon loadings as a tracer of anthropogenic aerosol inputs to oceanic regions is explored on the basis of measurements from a NE Atlantic cruise.

  16. 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.

  17. 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

  18. SU-E-T-491: Importance of Energy Dependent Protons Per MU Calibration Factors in IMPT Dose Calculations Using Monte Carlo Technique

    SciTech Connect

    Randeniya, S; Mirkovic, D; Titt, U; Guan, F; Mohan, R

    2014-06-01

    Purpose: In intensity modulated proton therapy (IMPT), energy dependent, protons per monitor unit (MU) calibration factors are important parameters that determine absolute dose values from energy deposition data obtained from Monte Carlo (MC) simulations. Purpose of this study was to assess the sensitivity of MC-computed absolute dose distributions to the protons/MU calibration factors in IMPT. Methods: A “verification plan” (i.e., treatment beams applied individually to water phantom) of a head and neck patient plan was calculated using MC technique. The patient plan had three beams; one posterior-anterior (PA); two anterior oblique. Dose prescription was 66 Gy in 30 fractions. Of the total MUs, 58% was delivered in PA beam, 25% and 17% in other two. Energy deposition data obtained from the MC simulation were converted to Gy using energy dependent protons/MU calibrations factors obtained from two methods. First method is based on experimental measurements and MC simulations. Second is based on hand calculations, based on how many ion pairs were produced per proton in the dose monitor and how many ion pairs is equal to 1 MU (vendor recommended method). Dose distributions obtained from method one was compared with those from method two. Results: Average difference of 8% in protons/MU calibration factors between method one and two converted into 27 % difference in absolute dose values for PA beam; although dose distributions preserved the shape of 3D dose distribution qualitatively, they were different quantitatively. For two oblique beams, significant difference in absolute dose was not observed. Conclusion: Results demonstrate that protons/MU calibration factors can have a significant impact on absolute dose values in IMPT depending on the fraction of MUs delivered. When number of MUs increases the effect due to the calibration factors amplify. In determining protons/MU calibration factors, experimental method should be preferred in MC dose calculations

  19. Solar Energetic Particle Drifts and the Energy Dependence of 1 AU Charge States

    NASA Astrophysics Data System (ADS)

    Dalla, S.; Marsh, M. S.; Battarbee, M.

    2017-01-01

    The event-averaged charge state of heavy ion solar energetic particles (SEPs), measured at 1 au from the Sun, typically increases with the ions’ kinetic energy. The origin of this behavior has been ascribed to processes taking place within the acceleration region. In this paper we study the propagation through interplanetary space of SEP Fe ions, injected near the Sun with a variety of charge states that are uniformly distributed in energy, by means of a 3D test particle model. In our simulations, due to gradient and curvature drifts associated with the Parker spiral magnetic field, ions of different charge propagate with very different efficiencies to an observer that is not magnetically well connected to the source region. As a result we find that, for many observer locations, the 1 au event-averaged charge state < Q> , as obtained from our model, displays an increase with particle energy E, in qualitative agreement with spacecraft observations. We conclude that drift-associated propagation is a possible explanation for the observed distribution of < Q> versus E in SEP events, and that the distribution measured in interplanetary space cannot be taken to represent that at injection.

  20. Models for Temperature and Composition in Uranus from Spitzer, Herschel and Ground-Based Infrared through Millimeter Observations

    NASA Astrophysics Data System (ADS)

    Orton, G. S.; Fletcher, L. N.; Feuchtgruber, H.; Lellouch, E.; Moreno, R.; Encrenaz, T.; Hartogh, P.; Jarchow, C.; Swinyard, B.; Moses, J. I.; Burgdorf, M. J.; Hammel, H. B.; Line, M. R.; Sandell, G.; Dowell, C. D.

    2013-12-01

    Photometric and spectroscopic observations of Uranus were combined to create self-consistent models of its global-mean temperature profile, bulk composition, and vertical distribution of gases. These were derived from a suite of spacecraft and ground-based observations that includes the Spitzer IRS, and the Herschel HIFI, PACS and SPIRE instruments, together with ground-based observations from UKIRT and CSO. Observations of the collision-induced absorption of H2 have constrained the temperature structure in the troposphere; this was possible up to atmospheric pressures of ~2 bars. Temperatures in the stratosphere were constrained by H2 quadrupole line emission. We coupled the vertical distribution of CH4 in the stratosphere of Uranus with models for the vertical mixing in a way that is consistent with the mixing ratios of hydrocarbons whose abundances are influenced primarily by mixing rather than chemistry. Spitzer and Herschel data constrain the abundances of CH3, CH4, C2H2, C2H6, C3H4, C4H2, H2O and CO2. At millimeter wavelengths, there is evidence that an additional opacity source is required besides the H2 collision-induced absorption and the NH3 absorption needed to match the microwave spectrum; this can reasonably (but not uniquely) be attributed to H2S. These models will be made more mature by consideration of spatial variability from Voyager IRIS and more recent spatially resolved imaging and mapping from ground-based observatories. The model is of ';programmatic' interest because it serves as a calibration source for Herschel instruments, and it provides a starting point for planning future spacecraft investigations of the atmosphere of Uranus.

  1. Axial anomaly and energy dependence of hyperon polarization in heavy-ion collisions

    NASA Astrophysics Data System (ADS)

    Sorin, Alexander; Teryaev, Oleg

    2017-01-01

    We address the issue of energy and charge dependence of global polarization of Λ hyperons in peripheral Au-Au collisions recently observed by the STAR Collaboration at Relativistic Heavy Ion Collider (RHIC). We compare different contributions to the anomalous mechanism relating polarization to vorticity and hydrodynamic helicity in QCD matter. We stress that the suppression of the gravitational anomaly contribution in strongly correlated matter observed in lattice simulations confirms our earlier prediction of rapid decrease of polarization with increasing collision energy. Our mechanism leads to polarization of Λ ¯ of the same sign and larger magnitude than the polarization of Λ. The energy and charge dependence of polarization is suggested as a sensitive probe of fine details of QCD matter structure.

  2. Energy dependent variability and outburst evolution in black hole X-ray binaries

    NASA Astrophysics Data System (ADS)

    Stiele, H.; Kong, A. K. H.

    2016-12-01

    Almost all low mass black hole X-ray binaries are transient sources. Most of these sources show a certain pattern during outburst: the evolution from low hard state through intermediate state(s) into high soft state and the returning to the hard state at lower luminosity. However, there are outbursts that remain in the hard state (so called "failed" outbursts). Using the technique of covariance spectra we can investigate the variability of individual spectral components on different time scales. Comprehensive studies of covariance spectra for a sample of black hole X-ray binaries observed in the rising low hard state of "normal" outbursts revealed an increase of the covariance ratios towards lower energies that has been interpreted as the sign of additional disc variability on long time scales. There are now two sources (h1743 and gs) that do not show an increase towards lower energies in their covariance ratio. Both sources have been observed during "failed" outbursts and showed photon indices much harder than what is usually observed in black hole X-ray binaries.

  3. Cosmic-ray composition measurements and cosmic ray background-free γ -ray observations with Cherenkov telescopes

    NASA Astrophysics Data System (ADS)

    Neronov, Andrii; Semikoz, Dmitri V.; Vovk, Ievgen; Mirzoyan, Razmik

    2016-12-01

    The muon component of extensive air showers (EAS) initiated by cosmic-ray particles carries information on the primary particle identity. We show that the muon content of EAS could be measured in a broad energy range from 10-100 TeV up to ultra-high-energy cosmic-ray range using wide field-of-view imaging atmospheric Cherenkov telescopes observing strongly inclined or nearly horizontal EAS from the ground of from high altitude. Cherenkov emission from muons in such EAS forms a distinct component (halo or tail) of the EAS image in the telescope camera. We show that detection of the muon signal could be used to measure composition of the cosmic-ray spectrum in the energy ranges of the knee, the ankle and of the Galactic-to-extragalactic transition. It could also be used to veto the cosmic-ray background in gamma-ray observations. This technique provides a possibility for up to 2 orders of magnitude improvement of sensitivity for γ -ray flux in the energy band above 10 PeV, compared to KASCADE-Grande, and an order-of-magnitude improvement of sensitivity in the multi-EeV energy band, compared to Pierre Auger Observatory.

  4. 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.

  5. Measurement of the energy dependence of X-ray-induced decomposition of potassium chlorate.

    PubMed

    Pravica, Michael; Bai, Ligang; Sneed, Daniel; Park, Changyong

    2013-03-21

    We report the first measurements of the X-ray induced decomposition of KClO3 as a function of energy in two experiments. KClO3 was pressurized to 3.5 GPa and irradiated with monochromatic synchrotron X-rays ranging in energy from 15 to 35 keV in 5 keV increments. A systematic increase in the decomposition rate as the energy was decreased was observed, which agrees with the 1/E(3) trend for the photoelectric process, except at the lowest energy studied. A second experiment was performed to access lower energies (10 and 12 keV) using a beryllium gasket; suggesting an apparent resonance near 15 keV or 0.83 Ǻ maximizing the chemical decomposition rate. A third experiment was performed using KIO3 to ascertain the anionic dependence of the decomposition rate, which was observed to be far slower than in KClO3, suggesting that the O-O distance is the critical factor in chemical reactions. These results will be important for more efficiently initiating chemical decomposition in materials using selected X-ray wavelengths that maximize decomposition to aid useful hard X-ray-induced chemistry and contribute understanding of the mechanism of X-ray-induced decomposition of the chlorates.

  6. Energy dependence of the ridge in high multiplicity proton-proton collisions

    SciTech Connect

    Dusling, Kevin; Tribedy, Prithwish; Venugopalan, Raju

    2016-01-27

    In this study, we demonstrate that the recent measurement of azimuthally collimated, long-range rapidity (“ridge”) correlations in √s=13 TeV proton-proton (p+p) collisions by the ATLAS Collaboration at the LHC are in agreement with expectations from the color glass condensate effective theory of high-energy QCD. The observation that the integrated near-side yield as a function of multiplicity is independent of collision energy is a natural consequence of the fact that multiparticle production is driven by a single semihard saturation scale in the color glass condensate framework. We argue further that the azimuthal structure of these recent ATLAS ridge measurements strongly constrains hydrodynamic interpretations of such correlations in high-multiplicity p+p collisions.

  7. Energy dependence of the ridge in high multiplicity proton-proton collisions

    DOE PAGES

    Dusling, Kevin; Tribedy, Prithwish; Venugopalan, Raju

    2016-01-27

    In this study, we demonstrate that the recent measurement of azimuthally collimated, long-range rapidity (“ridge”) correlations in √s=13 TeV proton-proton (p+p) collisions by the ATLAS Collaboration at the LHC are in agreement with expectations from the color glass condensate effective theory of high-energy QCD. The observation that the integrated near-side yield as a function of multiplicity is independent of collision energy is a natural consequence of the fact that multiparticle production is driven by a single semihard saturation scale in the color glass condensate framework. We argue further that the azimuthal structure of these recent ATLAS ridge measurements strongly constrainsmore » hydrodynamic interpretations of such correlations in high-multiplicity p+p collisions.« less

  8. Energy dependence of the transverse momentum distributions of charged particles in pp collisions measured by ALICE.

    PubMed

    Abelev, B; Adam, J; Adamová, D; Adare, A M; Aggarwal, M M; Aglieri Rinella, G; Agnello, M; Agocs, A G; Agostinelli, A; Ahammed, Z; Ahmad, N; Ahmad Masoodi, A; Ahmed, I; Ahn, S A; Ahn, S U; Aimo, I; Aiola, S; Ajaz, M; Akindinov, A; Aleksandrov, D; Alessandro, B; Alexandre, D; Alici, A; Alkin, A; Alme, J; Alt, T; Altini, V; Altinpinar, S; Altsybeev, I; Alves Garcia Prado, C; Andrei, C; Andronic, A; Anguelov, V; Anielski, J; Antičić, T; Antinori, F; Antonioli, P; Aphecetche, L; Appelshäuser, H; Arbor, N; Arcelli, S; Armesto, N; Arnaldi, R; Aronsson, T; Arsene, I C; Arslandok, M; Augustinus, A; Averbeck, R; Awes, T C; Äystö, J; Azmi, M D; Bach, M; Badalà, A; Baek, Y W; Bailhache, R; Bala, R; Baldisseri, A; Baltasar Dos Santos Pedrosa, F; Bán, J; Baral, R C; Barbera, R; Barile, F; Barnaföldi, G G; Barnby, L S; Barret, V; Bartke, J; Basile, M; Bastid, N; Basu, S; Bathen, B; Batigne, G; Batyunya, B; Batzing, P C; Baumann, C; Bearden, I G; Beck, H; Bedda, C; Behera, N K; Belikov, I; Bellini, F; Bellwied, R; Belmont-Moreno, E; Bencedi, G; Beole, S; Berceanu, I; Bercuci, A; Berdnikov, Y; Berenyi, D; Bergognon, A A E; Bertens, R A; Berzano, D; Betev, L; Bhasin, A; Bhati, A K; Bhom, J; Bianchi, L; Bianchi, N; Bianchin, C; Bielčík, J; Bielčíková, J; Bilandzic, A; Bjelogrlic, S; Blanco, F; Blanco, F; Blau, D; Blume, C; Bock, F; Bogdanov, A; Bøggild, H; Bogolyubsky, M; Boldizsár, L; Bombara, M; Book, J; Borel, H; Borissov, A; Bornschein, J; Botje, M; Botta, E; Böttger, S; Braidot, E; Braun-Munzinger, P; Bregant, M; Breitner, T; Broker, T A; Browning, T A; Broz, M; Brun, R; Bruna, E; Bruno, G E; Budnikov, D; Buesching, H; Bufalino, S; Buncic, P; Busch, O; Buthelezi, Z; Caffarri, D; Cai, X; Caines, H; Caliva, A; Calvo Villar, E; Camerini, P; Canoa Roman, V; Cara Romeo, G; Carena, F; Carena, W; Carminati, F; Casanova Díaz, A; Castillo Castellanos, J; Casula, E A R; Catanescu, V; Cavicchioli, C; Ceballos Sanchez, C; Cepila, J; Cerello, P; Chang, B; Chapeland, S; Charvet, J L; Chattopadhyay, S; Chattopadhyay, S; Cherney, M; Cheshkov, C; Cheynis, B; Chibante Barroso, V; Chinellato, D D; Chochula, P; Chojnacki, M; Choudhury, S; Christakoglou, P; Christensen, C H; Christiansen, P; Chujo, T; Chung, S U; Cicalo, C; Cifarelli, L; Cindolo, F; Cleymans, J; Colamaria, F; Colella, D; Collu, A; Colocci, M; Conesa Balbastre, G; Conesa Del Valle, Z; Connors, M E; Contin, G; Contreras, J G; Cormier, T M; Corrales Morales, Y; Cortese, P; Cortés Maldonado, I; Cosentino, M R; Costa, F; Crochet, P; Cruz Albino, R; Cuautle, E; Cunqueiro, L; Dainese, A; Dang, R; Danu, A; Das, K; Das, D; Das, I; Dash, A; Dash, S; De, S; Delagrange, H; Deloff, A; Dénes, E; Deppman, A; de Barros, G O V; De Caro, A; de Cataldo, G; de Cuveland, J; De Falco, A; De Gruttola, D; De Marco, N; De Pasquale, S; de Rooij, R; Diaz Corchero, M A; Dietel, T; Divià, R; Di Bari, D; Di Giglio, C; Di Liberto, S; Di Mauro, A; Di Nezza, P; Djuvsland, Ø; Dobrin, A; Dobrowolski, T; Dönigus, B; Dordic, O; Dubey, A K; Dubla, A; Ducroux, L; Dupieux, P; Dutta Majumdar, A K; D Erasmo, G; Elia, D; Emschermann, D; Engel, H; Erazmus, B; Erdal, H A; Eschweiler, D; Espagnon, B; Estienne, M; Esumi, S; Evans, D; Evdokimov, S; Eyyubova, G; Fabris, D; Faivre, J; Falchieri, D; Fantoni, A; Fasel, M; Fehlker, D; Feldkamp, L; Felea, D; Feliciello, A; Feofilov, G; Fernández Téllez, A; Ferreiro, E G; Ferretti, A; Festanti, A; Figiel, J; Figueredo, M A S; Filchagin, S; Finogeev, D; Fionda, F M; Fiore, E M; Floratos, E; Floris, M; Foertsch, S; Foka, P; Fokin, S; Fragiacomo, E; Francescon, A; Frankenfeld, U; Fuchs, U; Furget, C; Fusco Girard, M; Gaardhøje, J J; Gagliardi, M; Gago, A; Gallio, M; Gangadharan, D R; Ganoti, P; Garabatos, C; Garcia-Solis, E; Gargiulo, C; Garishvili, I; Gerhard, J; Germain, M; Gheata, A; Gheata, M; Ghidini, B; Ghosh, P; Gianotti, P; Giubellino, P; Gladysz-Dziadus, E; Glässel, P; Goerlich, L; Gomez, R; González-Zamora, P; Gorbunov, S; Gotovac, S; Graczykowski, L K; Grajcarek, R; Grelli, A; Grigoras, C; Grigoras, A; Grigoriev, V; Grigoryan, A; Grigoryan, S; Grinyov, B; Grion, N; Grosse-Oetringhaus, J F; Grossiord, J-Y; Grosso, R; Guber, F; Guernane, R; Guerzoni, B; Guilbaud, M; Gulbrandsen, K; Gulkanyan, H; Gunji, T; Gupta, A; Gupta, R; Khan, K H; Haake, R; Haaland, Ø; Hadjidakis, C; Haiduc, M; Hamagaki, H; Hamar, G; Hanratty, L D; Hansen, A; Harris, J W; Harton, A; Hatzifotiadou, D; Hayashi, S; Hayrapetyan, A; Heckel, S T; Heide, M; Helstrup, H; Herghelegiu, A; Herrera Corral, G; Herrmann, N; Hess, B A; Hetland, K F; Hicks, B; Hippolyte, B; Hori, Y; Hristov, P; Hřivnáčová, I; Huang, M; Humanic, T J; Hutter, D; Hwang, D S; Ichou, R; Ilkaev, R; Ilkiv, I; Inaba, M; Incani, E; Innocenti, G M; Ionita, C; Ippolitov, M; Irfan, M; Ivanov, V; Ivanov, M; Ivanytskyi, O; Jachołkowski, A; Jahnke, C; Jang, H J; Janik, M A; Jayarathna, P H S Y; Jena, S; Jimenez Bustamante, R T; Jones, P G; Jung, H; Jusko, A; Kalcher, S; Kaliňák, P; Kalliokoski, T; Kalweit, A; Kang, J H; Kaplin, V; Kar, S; Karasu Uysal, A; Karavichev, O; Karavicheva, T; Karpechev, E; Kazantsev, A; Kebschull, U; Keidel, R; Ketzer, B; Khan, S A; Khan, M M; Khan, P; Khanzadeev, A; Kharlov, Y; Kileng, B; Kim, S; Kim, D W; Kim, D J; Kim, B; Kim, T; Kim, M; Kim, M; Kim, J S; Kirsch, S; Kisel, I; Kiselev, S; Kisiel, A; Kiss, G; Klay, J L; Klein, J; Klein-Bösing, C; Kluge, A; Knichel, M L; Knospe, A G; Köhler, M K; Kollegger, T; Kolojvari, A; Kondratiev, V; Kondratyeva, N; Konevskikh, A; Kovalenko, V; Kowalski, M; Kox, S; Koyithatta Meethaleveedu, G; Kral, J; Králik, I; Kramer, F; Kravčáková, A; Krelina, M; Kretz, M; Krivda, M; Krizek, F; Krus, M; Kryshen, E; Krzewicki, M; Kucera, V; Kucheriaev, Y; Kugathasan, T; Kuhn, C; Kuijer, P G; Kulakov, I; Kumar, J; Kurashvili, P; Kurepin, A B; Kurepin, A; Kuryakin, A; Kushpil, S; Kushpil, V; Kweon, M J; Kwon, Y; Ladrón de Guevara, P; Lagana Fernandes, C; Lakomov, I; Langoy, R; Lara, C; Lardeux, A; La Pointe, S L; La Rocca, P; Lea, R; Lechman, M; Lee, S C; Lee, G R; Legrand, I; Lehnert, J; Lemmon, R C; Lenhardt, M; Lenti, V; León Monzón, I; Lévai, P; Li, S; Lien, J; Lietava, R; Lindal, S; Lindenstruth, V; Lippmann, C; Lisa, M A; Ljunggren, H M; Lodato, D F; Loenne, P I; Loggins, V R; Loginov, V; Lohner, D; Loizides, C; Loo, K K; Lopez, X; López Torres, E; Løvhøiden, G; Lu, X-G; Luettig, P; Lunardon, M; Luo, J; Luparello, G; Luzzi, C; Jacobs, P M; Ma, R; Maevskaya, A; Mager, M; Mahapatra, D P; Maire, A; Malaev, M; Maldonado Cervantes, I; Malinina, L; Mal'Kevich, D; Malzacher, P; Mamonov, A; Manceau, L; Manko, V; Manso, F; Manzari, V; Marchisone, M; Mareš, J; Margagliotti, G V; Margotti, A; Marín, A; Markert, C; Marquard, M; Martashvili, I; Martin, N A; Martinengo, P; Martínez, M I; Martínez García, G; Martin Blanco, J; Martynov, Y; Mas, A; Masciocchi, S; Masera, M; Masoni, A; Massacrier, L; Mastroserio, A; Matyja, A; Mazer, J; Mazumder, R; Mazzoni, M A; Meddi, F; Menchaca-Rocha, A; Mercado Pérez, J; Meres, M; Miake, Y; Mikhaylov, K; Milano, L; Milosevic, J; Mischke, A; Mishra, A N; Miśkowiec, D; Mitu, C; Mlynarz, J; Mohanty, B; Molnar, L; Montaño Zetina, L; Monteno, M; Montes, E; Moon, T; Morando, M; Moreira De Godoy, D A; Moretto, S; Morreale, A; Morsch, A; Muccifora, V; Mudnic, E; Muhuri, S; Mukherjee, M; Müller, H; Munhoz, M G; Murray, S; Musa, L; Nandi, B K; Nania, R; Nappi, E; Nattrass, C; Nayak, T K; Nazarenko, S; Nedosekin, A; Nicassio, M; Niculescu, M; Nielsen, B S; Nikolaev, S; Nikulin, S; Nikulin, V; Nilsen, B S; Nilsson, M S; Noferini, F; Nomokonov, P; Nooren, G; Nyanin, A; Nyatha, A; Nystrand, J; Oeschler, H; Oh, S K; Oh, S; Olah, L; Oleniacz, J; Oliveira Da Silva, A C; Onderwaater, J; Oppedisano, C; Ortiz Velasquez, A; Oskarsson, A; Otwinowski, J; Oyama, K; Pachmayer, Y; Pachr, M; Pagano, P; Paić, G; Painke, F; Pajares, C; Pal, S K; Palaha, A; Palmeri, A; Papikyan, V; Pappalardo, G S; Park, W J; Passfeld, A; Patalakha, D I; Paticchio, V; Paul, B; Pawlak, T; Peitzmann, T; Pereira Da Costa, H; Pereira De Oliveira Filho, E; Peresunko, D; Pérez Lara, C E; Perrino, D; Peryt, W; Pesci, A; Pestov, Y; Petráček, V; Petran, M; Petris, M; Petrov, P; Petrovici, M; Petta, C; Piano, S; Pikna, M; Pillot, P; Pinazza, O; Pinsky, L; Pitz, N; Piyarathna, D B; Planinic, M; Płoskoń, M; Pluta, J; Pochybova, S; Podesta-Lerma, P L M; Poghosyan, M G; Polichtchouk, B; Poljak, N; Pop, A; Porteboeuf-Houssais, S; Pospíšil, V; Potukuchi, B; Prasad, S K; Preghenella, R; Prino, F; Pruneau, C A; Pshenichnov, I; Puddu, G; Punin, V; Putschke, J; Qvigstad, H; Rachevski, A; Rademakers, A; Rak, J; Rakotozafindrabe, A; Ramello, L; Raniwala, S; Raniwala, R; Räsänen, S S; Rascanu, B T; Rathee, D; Rauch, W; Rauf, A W; Razazi, V; Read, K F; Real, J S; Redlich, K; Reed, R J; Rehman, A; Reichelt, P; Reicher, M; Reidt, F; Renfordt, R; Reolon, A R; Reshetin, A; Rettig, F; Revol, J-P; Reygers, K; Riccati, L; Ricci, R A; Richert, T; Richter, M; Riedler, P; Riegler, W; Riggi, F; Rivetti, A; Rodríguez Cahuantzi, M; Rodriguez Manso, A; Røed, K; Rogochaya, E; Rohni, S; Rohr, D; Röhrich, D; Romita, R; Ronchetti, F; Rosnet, P; Rossegger, S; Rossi, A; Roy, P; Roy, C; Rubio Montero, A J; Rui, R; Russo, R; Ryabinkin, E; Rybicki, A; Sadovsky, S; Šafařík, K; Sahoo, R; Sahu, P K; Saini, J; Sakaguchi, H; Sakai, S; Sakata, D; Salgado, C A; Salzwedel, J; Sambyal, S; Samsonov, V; Sanchez Castro, X; Šándor, L; Sandoval, A; Sano, M; Santagati, G; Santoro, R; Sarkar, D; Scapparone, E; Scarlassara, F; Scharenberg, R P; Schiaua, C; Schicker, R; Schmidt, C; Schmidt, H R; Schuchmann, S; Schukraft, J; Schulc, M; Schuster, T; Schutz, Y; Schwarz, K; Schweda, K; Scioli, G; Scomparin, E; Scott, R; Scott, P A; Segato, G; Selyuzhenkov, I; Seo, J; Serci, S; Serradilla, E; Sevcenco, A; Shabetai, A; Shabratova, G; Shahoyan, R; Sharma, S; Sharma, N; Shigaki, K; Shtejer, K; Sibiriak, Y; Siddhanta, S; Siemiarczuk, T; Silvermyr, D; Silvestre, C; Simatovic, G; Singaraju, R; Singh, R; Singha, S; Singhal, V; Sinha, B C; Sinha, T; Sitar, B; Sitta, M; Skaali, T B; Skjerdal, K; Smakal, R; Smirnov, N; Snellings, R J M; Søgaard, C; Soltz, R; Song, M; Song, J; Soos, C; Soramel, F; Spacek, M; Sputowska, I; Spyropoulou-Stassinaki, M; Srivastava, B K; Stachel, J; Stan, I; Stefanek, G; Steinpreis, M; Stenlund, E; Steyn, G; Stiller, J H; Stocco, D; Stolpovskiy, M; Strmen, P; Suaide, A A P; Subieta Vásquez, M A; Sugitate, T; Suire, C; Suleymanov, M; Sultanov, R; Šumbera, M; Susa, T; Symons, T J M; Szanto de Toledo, A; Szarka, I; Szczepankiewicz, A; Szymański, M; Takahashi, J; Tangaro, M A; Tapia Takaki, J D; Tarantola Peloni, A; Tarazona Martinez, A; Tauro, A; Tejeda Muñoz, G; Telesca, A; Terrevoli, C; Ter Minasyan, A; Thäder, J; Thomas, D; Tieulent, R; Timmins, A R; Toia, A; Torii, H; Trubnikov, V; Trzaska, W H; Tsuji, T; Tumkin, A; Turrisi, R; Tveter, T S; Ulery, J; Ullaland, K; Ulrich, J; Uras, A; Urciuoli, G M; Usai, G L; Vajzer, M; Vala, M; Valencia Palomo, L; Vande Vyvre, P; Vannucci, L; Van Hoorne, J W; van Leeuwen, M; Vargas, A; Varma, R; Vasileiou, M; Vasiliev, A; Vechernin, V; Veldhoen, M; Venaruzzo, M; Vercellin, E; Vergara, S; Vernet, R; Verweij, M; Vickovic, L; Viesti, G; Viinikainen, J; Vilakazi, Z; Villalobos Baillie, O; Vinogradov, A; Vinogradov, L; Vinogradov, Y; Virgili, T; Viyogi, Y P; Vodopyanov, A; Völkl, M A; Voloshin, S; Voloshin, K; Volpe, G; von Haller, B; Vorobyev, I; Vranic, D; Vrláková, J; Vulpescu, B; Vyushin, A; Wagner, B; Wagner, V; Wagner, J; Wang, Y; Wang, Y; Wang, M; Watanabe, D; Watanabe, K; Weber, M; Wessels, J P; Westerhoff, U; Wiechula, J; Wikne, J; Wilde, M; Wilk, G; Wilkinson, J; Williams, M C S; Windelband, B; Winn, M; Xiang, C; Yaldo, C G; Yamaguchi, Y; Yang, H; Yang, P; Yang, S; Yano, S; Yasnopolskiy, S; Yi, J; Yin, Z; Yoo, I-K; Yushmanov, I; Zaccolo, V; Zach, C; Zampolli, C; Zaporozhets, S; Zarochentsev, A; Závada, P; Zaviyalov, N; Zbroszczyk, H; Zelnicek, P; Zgura, I S; Zhalov, M; Zhang, F; Zhang, Y; Zhang, H; Zhang, X; Zhou, D; Zhou, Y; Zhou, F; Zhu, X; Zhu, J; Zhu, J; Zhu, H; Zichichi, A; Zimmermann, M B; Zimmermann, A; Zinovjev, G; Zoccarato, Y; Zynovyev, M; Zyzak, M

    Differential cross sections of charged particles in inelastic pp collisions as a function of pT have been measured at [Formula: see text] at the LHC. The pT spectra are compared to NLO-pQCD calculations. Though the differential cross section for an individual [Formula: see text] cannot be described by NLO-pQCD, the relative increase of cross section with [Formula: see text] is in agreement with NLO-pQCD. Based on these measurements and observations, procedures are discussed to construct pp reference spectra at [Formula: see text] up to pT=50 GeV/c as required for the calculation of the nuclear modification factor in nucleus-nucleus and proton-nucleus collisions.

  9. Mass-number and excitation-energy dependence of the spin cutoff parameter

    SciTech Connect

    Grimes, S. M.; Voinov, A. V.; Massey, T. N.

    2016-07-12

    Here, the spin cutoff parameter determining the nuclear level density spin distribution ρ(J) is defined through the spin projection as < J2z > 1/2 or equivalently for spherical nuclei, (< J(J+1) >/3)1/2. It is needed to divide the total level density into levels as a function of J. To obtain the total level density at the neutron binding energy from the s-wave resonance count, the spin cutoff parameter is also needed. The spin cutoff parameter has been calculated as a function of excitation energy and mass with a super-conducting Hamiltonian. Calculations have been compared with two commonly used semiempirical formulas. A need for further measurements is also observed. Some complications for deformed nuclei are discussed. The quality of spin cut off parameter data derived from isomeric ratio measurement is examined.

  10. Mass-number and excitation-energy dependence of the spin cutoff parameter

    DOE PAGES

    Grimes, S. M.; Voinov, A. V.; Massey, T. N.

    2016-07-12

    Here, the spin cutoff parameter determining the nuclear level density spin distribution ρ(J) is defined through the spin projection as < J2z > 1/2 or equivalently for spherical nuclei, (< J(J+1) >/3)1/2. It is needed to divide the total level density into levels as a function of J. To obtain the total level density at the neutron binding energy from the s-wave resonance count, the spin cutoff parameter is also needed. The spin cutoff parameter has been calculated as a function of excitation energy and mass with a super-conducting Hamiltonian. Calculations have been compared with two commonly used semiempirical formulas.more » A need for further measurements is also observed. Some complications for deformed nuclei are discussed. The quality of spin cut off parameter data derived from isomeric ratio measurement is examined.« less

  11. Internal Energy Dependence of Molecular Condensation Coefficients Determined from Molecular Beam Surface Scattering Experiments

    DOE R&D Accomplishments Database

    Sibener, S. J.; Lee, Y. T.

    1978-05-01

    An experiment was performed which confirms the existence of an internal mode dependence of molecular sticking probabilities for collisions of molecules with a cold surface. The scattering of a velocity selected effusive beam of CCl{sub 4} from a 90 K CC1{sub 4} ice surface has been studied at five translational velocities and for two different internal temperatures. At a surface temperature of 90 K (approx. 99% sticking probability) a four fold increase in reflected intensity was observed for the internally excited (560 K) CC1{sub 4} relative to the room temperature (298 K) CC1{sub 4} at a translational velocity of 2.5 X 10{sup 4} cm/sec. For a surface temperature of 90 K all angular distributions were found to peak 15{sup 0} superspecularly independent of incident velocity.

  12. Photon energy dependence of the light pressure exerted onto a thin silicon slab

    NASA Astrophysics Data System (ADS)

    Reinhart, F. K.; Boero, G.

    2011-04-01

    We review the theory of ponderomotive forces of classical nonionizing electromagnetic (EM) radiation exerted on dispersive matter. Minkowski's EM energy and momentum density lack any dispersion term in contrast to Nelson's theory, where they are included naturally. By considering force experiments on a dielectric mirror immersed in weakly dispersive liquids [R. V. Jones and B. Leslie, Proc. R. Soc. London, Ser. A1364-502110.1098/rspa.1978.0072 360, 347 (1978)], we found that the appearance of the dispersive term should depend on the phase of the mirror reflectivity. It thus matters if the electric or the magnetic field is dominant at the interface. Accordingly, the force measurements depend on the boundary condition and do not permit to uniquely determine the EM momentum in the liquids. Force measurements as a function of the reflectivity phase would permit to experimentally verify the expressions for the EM energy density in a dispersive medium. In our experiments, we chop light beams of different photon energies to excite the motion of a very thin and long Si slab near its mechanical resonance under UHV conditions. This permits to study the force response, where the power reflectivity of the sample varies from 0.7 to smaller than 10-3. The determination of the velocity of the slab with a Doppler interferometer yields the effective force exerted by the light beam. The measurements also confirm our theoretical considerations that the observed forces due to EM radiation cannot be traced to the EM momentum in matter, as the observed forces primarily depend on the boundary conditions. Minkowski's stress tensor remains applicable in our case thanks to the embedding of the Si slab in vacuum. Our quantitative analysis of the experimental data reveals an extra force of thermal origin most likely associated with the difference of the native oxide thickness on the surfaces of the slab. The estimated difference in oxide layer thickness amounts to ˜4 nm.

  13. Collision energy dependence of viscous hydrodynamic flow in relativistic heavy-ion collisions

    NASA Astrophysics Data System (ADS)

    Shen, Chun; Heinz, Ulrich

    2012-05-01

    Using a (2+1)-dimensional viscous hydrodynamical model, we study the dependence of flow observables on the collision energy ranging from s=7.7A GeV at the Relativistic Heavy Ion Collider (RHIC) to s=2760A GeV at the Large Hadron Collider (LHC). With a realistic equation of state, Glauber model initial conditions, and a small specific shear viscosity η/s=0.08, the differential charged hadron elliptic flow v2ch(pT,s) is found to exhibit a very broad maximum as a function of s around top RHIC energy, rendering it almost independent of collision energy for 39⩽s⩽2760A GeV. Compared to ideal fluid dynamical simulations, this “saturation” of elliptic flow is shifted to higher collision energies by shear viscous effects. For color-glass-motivated Monte Carlo-Kharzeev-Levin-Nardi initial conditions, which require a larger shear viscosity η/s=0.2 to reproduce the measured elliptic flow, a similar saturation is not observed up to LHC energies, except for very low pT. We emphasize that this saturation of the elliptic flow is not associated with the QCD phase transition, but arises from the interplay between radial and elliptic flow, which shifts with s depending on the fluid's viscosity and leads to a subtle cancellation between increasing contributions from light particles and decreasing contributions from heavy particles to v2 in the s range, where v2ch(pT,s) at fixed pT is maximal. By generalizing the definition of spatial eccentricity ɛx to isothermal hypersurfaces, we calculate ɛx on the kinetic freeze-out surface at different collision energies. Up to top RHIC energy, s=200A GeV, the fireball is still out-of-plane deformed at freeze-out, while at LHC energy the final spatial eccentricity is predicted to approach zero.

  14. Stoichiometric relationship between energy-dependent proton ejection and electron transport in mitochondria.

    PubMed

    Brand, M D; Reynafarje, B; Lehninger, A L

    1976-02-01

    The number of protons ejected during electron transport per pair of electrons per energy-conserving site (the H+/site ratio) was measured in rat liver mitochondria by three different methods under conditions in which transmembrane movements of endogenous phosphate were minized or eliminated. (1) In the Ca2+ pulse method, between 3.5 and 4.0 molecules of 3-hydroxybutyrate and 1.75 to 2.0 Ca2+ ions were accumulated per 2 e- per site during Ca2+ induced electron transport in the presence of rotenone, when measured under conditions in which movements of endogenous phosphate were negligible. Since entry of 3-hydroxybutyrate requires its protonation to the free acid these data correspond to an H+/site ratio of 3.5-4.0 (2) In the oxygen pulse method addition of known amounts of oxygen to anaerobic mitochondria in the presence of substrate yielded H+/site ratios of 3.0 when phosphate transport was eliminated by addition of N-ethylmaleimide or by anaerobic washing to remove endogenous phosphate. In the absence of such measures the observed H+/site ratio was 2.0. (3) In the reductant pulse method measurement of the initial steady rates of H+ ejection and oxygen consumption by mitochondria in an aerobic medium after addition of substrate gave H+/site near 4.0 in the presence of N-ethylmaleimide; in the absence of the inhibitor the observed ratio was only 2.0. These and other experiments reported indicate that the values of 2.0 earlier obtained for the H+/site ratio by Mitchell and Moyle [Biochem J. (1967) 105, 1147-1162] and others were underestimates due to the unrecognized masking of H+ ejection by movements of endogenous phosphate. The results presented here show that the H+/site ratio of mitochondrial electron transport is at least 3.0 and may be as high as 4.0.

  15. 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

  16. Isotopic dependence of fusion enhancement of various heavy ion systems using energy dependent Woods-Saxon potential

    NASA Astrophysics Data System (ADS)

    Gautam, Manjeet Singh

    2015-01-01

    In the present work, the fusion of symmetric and asymmetric projectile-target combinations are deeply analyzed within the framework of energy dependent Woods-Saxon potential model (EDWSP model) in conjunction with one dimensional Wong formula and the coupled channel code CCFULL. The neutron transfer channels and the inelastic surface excitations of collision partners are dominating mode of couplings and the coupling of relative motion of colliding nuclei to such relevant internal degrees of freedom produces a significant fusion enhancement at sub-barrier energies. It is quite interesting that the effects of dominant intrinsic degrees of freedom such as multi-phonon vibrational states, neutron transfer channels and proton transfer channels can be simulated by introducing the energy dependence in the nucleus-nucleus potential (EDWSP model). In the EDWSP model calculations, a wide range of diffuseness parameter ranging from a = 0.85 fm to a = 0.97 fm, which is much larger than a value (a = 0.65 fm) extracted from the elastic scattering data, is needed to reproduce sub-barrier fusion data. However, such diffuseness anomaly, which might be an artifact of some dynamical effects, has been resolved by trajectory fluctuation dissipation (TFD) model wherein the resulting nucleus-nucleus potential possesses normal diffuseness parameter.

  17. Demonstration of thermal dissipation of absorbed quanta during energy-dependent quenching of chlorophyll fluorescence in photosynthetic membranes.

    PubMed

    Yahyaoui, W; Harnois, J; Carpentier, R

    1998-11-27

    When plant leaves or chloroplasts are exposed to illumination that exceeds their photosynthetic capacity, photoprotective mechanisms such as described by the energy-dependent (non-photochemical) quenching of chlorophyll fluorescence are involved. The protective action is attributed to an increased rate constant for thermal dissipation of absorbed quanta. We applied photoacoustic spectroscopy to monitor thermal dissipation in spinach thylakoid membranes together with simultaneous measurement of chlorophyll fluorescence in the presence of inhibitors of opposite action on the formation of delta pH across the thylakoid membrane (tentoxin and nigericin/valinomycin). A linear relationship between the appearance of fluorescence quenching during formation of the delta pH and the reciprocal variation of thermal dissipation was demonstrated. Dicyclohexylcarbodiimide, which is known to prevent protonation of the minor light-harvesting complexes of photosystem II, significantly reduced the formation of fluorescence quenching and the concurrent increase in thermal dissipation. However, the addition of exogenous ascorbate to activate the xanthophyll de-epoxidase increased non-photochemical fluorescence quenching without affecting the measured thermal dissipation. It is concluded that a portion of energy-dependent fluorescence quenching that is independent of de-epoxidase activity can be readily measured by photoacoustic spectroscopy as an increase in thermal deactivation processes.

  18. Energy-dependent motion of TonB in the Gram-negative bacterial inner membrane

    PubMed Central

    Jordan, Lorne D.; Zhou, Yongyao; Smallwood, Chuck R.; Lill, Yoriko; Ritchie, Ken; Yip, Wai Tak; Newton, Salete M.; Klebba, Phillip E.

    2013-01-01

    Gram-negative bacteria acquire iron with TonB-dependent uptake systems. The TonB–ExbBD inner membrane complex is hypothesized to transfer energy to outer membrane (OM) iron transporters. Fluorescence microscopic characterization of green fluorescent protein (GFP)-TonB hybrid proteins revealed an unexpected, restricted localization of TonB in the cell envelope. Fluorescence polarization measurements demonstrated motion of TonB in living cells, which likely was rotation. By determining the anisotropy of GFP-TonB in the absence and presence of inhibitors, we saw the dependence of its motion on electrochemical force and on the actions of ExbBD. We observed higher anisotropy for GFP-TonB in energy-depleted cells and lower values in bacteria lacking ExbBD. However, the metabolic inhibitors did not change the anisotropy of GFP-TonB in ΔexbBD cells. These findings demonstrate that TonB undergoes energized motion in the bacterial cell envelope and that ExbBD couples this activity to the electrochemical gradient. The results portray TonB as an energized entity in a regular array underlying the OM bilayer, which promotes metal uptake through OM transporters by a rotational mechanism. PMID:23798405

  19. Excitation-energy dependence of solvation dynamics in room-temperature ionic liquids

    NASA Astrophysics Data System (ADS)

    Kim, Daekeon; Park, Sang-Won; Shim, Youngseon; Kim, Hyung J.; Jung, YounJoon

    2016-07-01

    Influence of the excitation energy of a probe solute molecule on its solvation dynamics and emission spectrum in 1-ethyl-3-methylimidazolium hexafluorophosphate (EMI+PF6-) is studied via molecular dynamics simulations using a coarse-grained model description. By exciting the probe at different energies, each with an extremely narrow distribution, ensuing solvent relaxation and its dynamic variance are monitored using the isoconfigurational ensemble method. Resulting Stokes shift function, S(t), indicates that long-time solvent relaxation becomes slower with the decreasing excitation energy and approaches the equilibrium correlation function, C(t), of solvent fluctuations. This suggests that the system excited at the red-edge of the spectrum observes linear response better than that at the blue-edge. A detailed analysis of nonequilibrium trajectories shows that the effect of initial configurations on variance of relaxation dynamics is mainly confined to short times; it reaches a maximum around 0.1 ≲ t ≲ 1 ps and diminishes as time further increases. The influence of the initial velocity distribution, on the other hand, tends to grow with time and dominates the long-time variations of dynamics. The emission spectrum shows the red-edge effect in accord with previous studies.

  20. Photon energy dependence of three fortuitous dosemeters from personal electronic devices, measured by optically stimulated luminescence.

    PubMed

    Beerten, Koen; Vanhavere, Filip

    2010-08-01

    New data are presented with regard to the relative OSL sensitivity of three different emergency dosemeters irradiated to various photon energies approximately between 48 and 1250 keV using blue excitation light. Investigated components extracted from commonly worn objects include those from USB flash drives (alumina substrate), mobile phones (Ba-rich silicate) and credit cards (chip card module). Several basic properties have been investigated such as the overall radiation sensitivity, the shape of the decay curve and fading of the OSL signal. An increase of the sensitivity for low energies relative to (60)Co gamma rays can be observed for the three dosemeters, the increase being very pronounced for the Ba-rich component (factor of 10) and less pronounced for the chip card module (factor of 2). It is concluded that proper dose correction factors for photon energy have to be applied in order to accurately determine the absorbed dose to tissue. The OSL sensitivity to neutron irradiation was investigated as well, but this was found to be less than the gamma sensitivity.

  1. Energy-dependent motion of TonB in the Gram-negative bacterial inner membrane.

    PubMed

    Jordan, Lorne D; Zhou, Yongyao; Smallwood, Chuck R; Lill, Yoriko; Ritchie, Ken; Yip, Wai Tak; Newton, Salete M; Klebba, Phillip E

    2013-07-09

    Gram-negative bacteria acquire iron with TonB-dependent uptake systems. The TonB-ExbBD inner membrane complex is hypothesized to transfer energy to outer membrane (OM) iron transporters. Fluorescence microscopic characterization of green fluorescent protein (GFP)-TonB hybrid proteins revealed an unexpected, restricted localization of TonB in the cell envelope. Fluorescence polarization measurements demonstrated motion of TonB in living cells, which likely was rotation. By determining the anisotropy of GFP-TonB in the absence and presence of inhibitors, we saw the dependence of its motion on electrochemical force and on the actions of ExbBD. We observed higher anisotropy for GFP-TonB in energy-depleted cells and lower values in bacteria lacking ExbBD. However, the metabolic inhibitors did not change the anisotropy of GFP-TonB in ΔexbBD cells. These findings demonstrate that TonB undergoes energized motion in the bacterial cell envelope and that ExbBD couples this activity to the electrochemical gradient. The results portray TonB as an energized entity in a regular array underlying the OM bilayer, which promotes metal uptake through OM transporters by a rotational mechanism.

  2. Beam Energy Dependence of the Third Harmonic of Azimuthal Correlations 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.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Attri, A.; Averichev, G. S.; Bai, X.; Bairathi, V.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Bouchet, J.; Brandenburg, J. D.; Brandin, A. V.; Bunzarov, I.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Campbell, J. M.; Cebra, D.; Chakaberia, I.; Chaloupka, P.; Chang, Z.; Chatterjee, A.; Chattopadhyay, S.; Chen, J. H.; Chen, X.; Cheng, J.; Cherney, M.; Christie, W.; Contin, G.; Crawford, H. J.; Das, S.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; di Ruzza, B.; Didenko, L.; Dilks, C.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Engelage, J.; Eppley, G.; Esha, R.; Evdokimov, O.; Eyser, O.; Fatemi, R.; Fazio, S.; Federic, P.; Fedorisin, J.; Feng, Z.; Filip, P.; Fisyak, Y.; Flores, C. E.; Fulek, L.; Gagliardi, C. A.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Greiner, L.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, S.; Gupta, A.; Guryn, W.; Hamad, A. I.; Hamed, A.; Haque, R.; Harris, J. W.; He, L.; Heppelmann, S.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Horvat, S.; Huang, T.; Huang, X.; Huang, B.; Huang, H. Z.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jang, H.; Jentsch, A.; Jia, J.; Jiang, K.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Khan, Z. H.; Kikoła, D. P.; Kisel, I.; Kisiel, A.; Kochenda, L.; Koetke, D. D.; Kosarzewski, L. K.; Kraishan, A. F.; Kravtsov, P.; Krueger, K.; Kumar, L.; Lamont, M. A. C.; Landgraf, J. M.; Landry, K. D.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; Li, X.; Li, C.; Li, X.; Li, Y.; Li, W.; Lin, T.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, X.; Ma, R.; Ma, G. L.; Ma, Y. G.; Ma, L.; Magdy, N.; Majka, R.; Manion, A.; Margetis, S.; Markert, C.; Matis, H. S.; McDonald, D.; McKinzie, S.; Meehan, K.; Mei, J. C.; Minaev, N. G.; Mioduszewski, S.; Mishra, D.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nigmatkulov, G.; Niida, T.; Nogach, L. V.; Noh, S. Y.; Novak, J.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Okorokov, V. A.; Olvitt, D.; Page, B. S.; Pak, R.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlik, B.; Pei, H.; Perkins, C.; Pile, P.; Pluta, J.; Poniatowska, K.; Porter, J.; Posik, M.; Poskanzer, A. M.; Pruthi, N. K.; Putschke, J.; Qiu, H.; Quintero, A.; Ramachandran, S.; Raniwala, S.; Raniwala, R.; Ray, R. L.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandweiss, J.; 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, A.; Sharma, B.; Sharma, M. K.; Shen, W. Q.; Shi, Z.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Sikora, R.; Simko, M.; Singha, S.; Skoby, M. J.; Smirnov, N.; Smirnov, D.; Solyst, W.; Song, L.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stepanov, M.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Sumbera, M.; Summa, B.; Sun, Z.; Sun, X. M.; Sun, Y.; Surrow, B.; Svirida, D. N.; Tang, Z.; Tang, A. H.; Tarnowsky, T.; Tawfik, A.; Thäder, J.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Todoroki, T.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Tripathy, S. K.; Tsai, O. D.; Ullrich, T.; Underwood, D. G.; Upsal, I.; Van Buren, G.; van Nieuwenhuizen, G.; Vandenbroucke, M.; Varma, R.; Vasiliev, A. N.; Vertesi, R.; Videbæk, F.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wang, F.; Wang, G.; Wang, J. S.; Wang, H.; Wang, Y.; Wang, Y.; Webb, G.; Webb, J. C.; Wen, L.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y.; Xiao, Z. G.; Xie, W.; Xie, G.; Xin, K.; Xu, Y. F.; Xu, Q. H.; Xu, N.; Xu, H.; Xu, Z.; Xu, J.; Yang, S.; Yang, Y.; Yang, Y.; Yang, C.; Yang, Y.; Yang, Q.; Ye, Z.; Ye, Z.; Yepes, P.; Yi, L.; Yip, K.; Yoo, I.-K.; Yu, N.; Zbroszczyk, H.; Zha, W.; Zhang, X. P.; Zhang, Y.; Zhang, J.; Zhang, J.; Zhang, S.; Zhang, S.; Zhang, Z.; Zhang, J. B.; Zhao, J.; Zhong, C.; Zhou, L.; Zhu, X.; Zoulkarneeva, Y.; Zyzak, M.; STAR Collaboration

    2016-03-01

    We present results from a harmonic decomposition of two-particle azimuthal correlations measured with the STAR detector in Au +Au collisions for energies ranging from √{sN N }=7.7 to 200 GeV. The third harmonic v32{2 }=⟨cos 3 (ϕ1-ϕ2)⟩ , where ϕ1-ϕ2 is the angular difference in azimuth, is studied as a function of the pseudorapidity difference between particle pairs Δ η =η1-η2 . Nonzero v32{2 } is directly related to the previously observed large-Δ η narrow-Δ ϕ ridge correlations and has been shown in models to be sensitive to the existence of a low viscosity quark gluon plasma phase. For sufficiently central collisions, v32{2 } persist down to an energy of 7.7 GeV, suggesting that quark gluon plasma may be created even in these low energy collisions. In peripheral collisions at these low energies, however, v32{2 } is consistent with zero. When scaled by the pseudorapidity density of charged-particle multiplicity per participating nucleon pair, v32{2 } for central collisions shows a minimum near √{sN N }=20 GeV .

  3. Energy Dependent Morphology in the PWN Candidate HESS J1825-137

    SciTech Connect

    Funk, S.; Hinton, J.A.; deJager, O.C.; /North West U., South Africa

    2007-09-26

    Observations with H.E.S.S. revealed a new source of very high-energy (VHE) gamma-rays above 100 GeV - HESS J1825-137 - extending mainly to the south of the energetic pulsar PSRB1823-13. A detailed spectral and morphological analysis of HESS J1825-137 reveals for the first time in VHE gamma-ray astronomy a steepening of the energy spectrum with increasing distance from the pulsar. This behavior can be understood by invoking radiative cooling of the IC-Compton gamma-ray emitting electrons during their propagation. In this scenario the vastly different sizes between the VHE gamma-ray emitting region and the X-ray PWN associated with PSRB1823-13 can be naturally explained by different cooling timescales for the radiating electron populations. If this scenario is correct, HESS J1825-137 can serve as a prototype for a whole class of asymmetric PWN in which the X-rays are extended over a much smaller angular scales than the gamma-rays and can help understanding recent detections of X-ray PWN in systems such as HESS J1640-465 and HESS J1813-178. The future GLAST satellite will probe lower electron energies shedding further light on cooling and diffusion processes in this source.

  4. 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

  5. ENERGY-DEPENDENT POWER SPECTRAL STATES AND ORIGIN OF APERIODIC VARIABILITY IN BLACK HOLE BINARIES

    SciTech Connect

    Yu Wenfei; Zhang Wenda

    2013-06-20

    We found that the black hole candidate MAXI J1659-152 showed distinct power spectra, i.e., power-law noise (PLN) versus band-limited noise (BLN) plus quasi-periodic oscillations (QPOs) below and above about 2 keV, respectively, in observations with Swift and the Rossi X-ray Timing Explorer during the 2010 outburst, indicating a high energy cutoff of the PLN and a low energy cutoff of the BLN and QPOs around 2 keV. The emergence of the PLN and the fading of the BLN and QPOs initially took place below 2 keV when the source entered the hard intermediate state and settled in the soft state three weeks later. The evolution was accompanied by the emergence of the disk spectral component and decreases in the amplitudes of variability in the soft and hard X-ray bands. Our results indicate that the PLN is associated with an optically thick disk in both hard and intermediate states, and the power spectral state is independent of the X-ray energy spectral state in a broadband view. We suggest that in the hard or intermediate state, the BLN and QPOs emerge from the innermost hot flow subjected to Comptonization, while the PLN originates from the optically thick disk farther out. The energy cutoffs of the PLN and the BLN or QPOs then follow the temperature of the seed photons from the inner edge of the optically thick disk, while the high frequency cutoff of the PLN follows the orbital frequency of the inner edge of the optically thick disk as well.

  6. 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.

  7. 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.

  8. Mineralogical composition of lunar central crater peaks inferred from NIR observations by the SIR-2 reflectance spectrometer on Chandrayaan-1

    NASA Astrophysics Data System (ADS)

    Mall, Urs; Combe, Jean-Philippe; Bugiolacchi, Roberto; Bhatt, Megha; Bhattacharya, Satadru; McKenna-Lawlor, Susan; SIR-2 Collaboration

    Since the return of lunar samples by the Apollo missions the lunar crust, which is believed to have been formed by differentiation of a global magma ocean, is known to be mostly made up of anorthosite (a plagioclase-rich rock). Denser, iron-rich and magnesium-rich minerals such as pyroxenes and olivines are sunk deeper into the interior. The mineralogy of the crust provides key information for refining chemical and thermodynamical models of lunar formation and evolution. Remote observations of the lunar crust and its quantitative compositional identification were partly hampered in the past from the experimental side by the fact that a combination of good spectral and spatial resolution of an imaged surface area is difficult to achieve. Also the mineralogical spectral deconvolution process of such observations is in itself quite complex. The identification of plagioclase has proved to pose a particular challenge. This challenge originates not only from the fact that the plagioclase characterizing absorption feature, which is located at around 1.3 m, is only detectable if trace amounts of Fe2+ are present in the mineral's structure, but also due to the fact that olivine and pyroxene have strong absorption bands around 1 m which dominate nearinfrared spectra. In addition, any analysis is complicated by the fact that experimental laboratory work has clearly demonstrated that changes in reflectance with increasing peak shock pressures in experimentally shocked plagioclase feldspar-rich rocks can occur and that these changes are nonlinear [1]. Despite these difficulties, new near-infrared spectrometers recently flown around the Moon have led to the identification of plagioclase on the lunar surface [2,3]. Among this new generation of spectrometers is the SIR-2 instrument, [4] flown on Chandrayaan-1. This instrument is a grating-based, compact, high-resolution pointing spectrometer operating in the spectral range 0.9-2.4 m. SIR-2 combines high spectral resolution ( 0

  9. Energy-dependent dynamics of keV to MeV electrons in the inner zone, outer zone, and slot regions.

    PubMed

    Reeves, Geoffrey D; Friedel, Reiner H W; Larsen, Brian A; Skoug, Ruth M; Funsten, Herbert O; Claudepierre, Seth G; Fennell, Joseph F; Turner, Drew L; Denton, Mick H; Spence, Harlan E; Blake, J Bernard; Baker, Daniel N

    2016-01-01

    We present observations of the radiation belts from the Helium Oxygen Proton Electron and Magnetic Electron Ion Spectrometer particle detectors on the Van Allen Probes satellites that illustrate the energy dependence and L shell dependence of radiation belt enhancements and decays. We survey events in 2013 and analyze an event on 1 March in more detail. The observations show the following: (a) at all L shells, lower energy electrons are enhanced more often than higher energies; (b) events that fill the slot region are more common at lower energies; (c) enhancements of electrons in the inner zone are more common at lower energies; and (d) even when events do not fully fill the slot region, enhancements at lower energies tend to extend to lower L shells than higher energies. During enhancement events the outer zone extends to lower L shells at lower energies while being confined to higher L shells at higher energies. The inner zone shows the opposite with an outer boundary at higher L shells for lower energies. Both boundaries are nearly straight in log(energy) versus L shell space. At energies below a few 100 keV, radiation belt electron penetration through the slot region into the inner zone is commonplace, but the number and frequency of "slot filling" events decreases with increasing energy. The inner zone is enhanced only at energies that penetrate through the slot. Energy- and L shell-dependent losses (that are consistent with whistler hiss interactions) return the belts to more quiescent conditions.

  10. Energy-dependent dynamics of keV to MeV electrons in the inner zone, outer zone, and slot regions

    SciTech Connect

    Reeves, Geoffrey D.; Friedel, Reiner H. W.; Larsen, Brian A.; Skoug, Ruth M.; Funsten, Herbert O.; Claudepierre, Seth G.; Fennell, Joseph F.; Turner, Drew L.; Denton, Mick H.; Spence, Harlan E.; Blake, J. Bernard; Baker, Daniel N.

    2016-01-28

    Here, we present observations of the radiation belts from the Helium Oxygen Proton Electron and Magnetic Electron Ion Spectrometer particle detectors on the Van Allen Probes satellites that illustrate the energy dependence and L shell dependence of radiation belt enhancements and decays. We survey events in 2013 and analyze an event on 1 March in more detail. The observations show the following: (a) at all L shells, lower energy electrons are enhanced more often than higher energies; (b) events that fill the slot region are more common at lower energies; (c) enhancements of electrons in the inner zone are more common at lower energies; and (d) even when events do not fully fill the slot region, enhancements at lower energies tend to extend to lower L shells than higher energies. During enhancement events the outer zone extends to lower L shells at lower energies while being confined to higher L shells at higher energies. The inner zone shows the opposite with an outer boundary at higher L shells for lower energies. Both boundaries are nearly straight in log(energy) versus L shell space. At energies below a few 100 keV, radiation belt electron penetration through the slot region into the inner zone is commonplace, but the number and frequency of “slot filling” events decreases with increasing energy. The inner zone is enhanced only at energies that penetrate through the slot. Energy- and L shell-dependent losses (that are consistent with whistler hiss interactions) return the belts to more quiescent conditions.

  11. {sup 57}Co(n,{gamma}){sup 58}Co reaction cross section: Thermal and resonance integral measurements and energy dependence

    SciTech Connect

    Maidana, Nora L.; Mesa, Joel; Vanin, Vito R.; Castro, Ruy M.; Dias, Mauro S.; Koskinas, Marina F.

    2004-07-01

    The {sup 57}Co(n,{gamma}){sup 58}Co thermal and resonance integral cross section were measured as 51(5) b and 20.0(19) b, respectively, by irradiating aliquots of {sup 57}Co solution sealed inside quartz bottles near the core of the IEA-R1 IPEN research reactor and counting the gamma-ray residual activity. The irradiations were monitored using Au-Al alloy foils, with and without Cd cover. The gamma-ray measurements were performed with a shielded HPGe detector. Westcott formalism was applied for the average neutron flux determination. The cross section energy dependence was evaluated using the multilevel Breit-Wigner expression considering the first two resonances and the statistical model for energies above the second resonance. Maxwellian averaged neutron capture cross section with neutron temperatures between 5 and 100 keV were also evaluated.

  12. Modelling of OPNMR phenomena using photon energy-dependent in GaAs and InP

    NASA Astrophysics Data System (ADS)

    Wheeler, Dustin D.; Willmering, Matthew M.; Sesti, Erika L.; Pan, Xingyuan; Saha, Dipta; Stanton, Christopher J.; Hayes, Sophia E.

    2016-12-01

    We have modified the model for optically-pumped NMR (OPNMR) to incorporate a revised expression for the expectation value of the z-projection of the electron spin, and apply this model to both bulk GaAs and a new material, InP. This expression includes the photon energy dependence of the electron polarization when optically pumping direct-gap semiconductors in excess of the bandgap energy, Eg . Rather than using a fixed value arising from coefficients (the matrix elements) for the optical transitions at the k = 0 bandedge, we define a new parameter, Sopt (Eph) . Incorporating this revised element into the expression for , we have simulated the photon energy dependence of the OPNMR signals from bulk semi-insulating GaAs and semi-insulating InP. In earlier work, we matched calculations of electron spin polarization (alone) to features in a plot of OPNMR signal intensity versus photon energy for optical pumping (Ramaswamy et al., 2010). By incorporating an electron spin polarization which varies with pump wavelength into the penetration depth model of OPNMR signal, we are able to model features in both III-V semiconductors. The agreement between the OPNMR data and the corresponding model demonstrates that fluctuations in the OPNMR intensity have particular sensitivity to light hole-to-conduction band transitions in bulk systems. We provide detailed plots of the theoretical predictions for optical pumping transition probabilities with circularly-polarized light for both helicities of light, broken down into illustrative plots of optical magnetoabsorption and spin polarization, shown separately for heavy-hole and light-hole transitions. These plots serve as an effective roadmap of transitions, which are helpful to other researchers investigating optical pumping effects.

  13. Energy Dependence of Measured CT Numbers on Substituted Materials Used for CT Number Calibration of Radiotherapy Treatment Planning Systems

    PubMed Central

    Mahmoudi, Reza; Jabbari, Nasrollah; aghdasi, Mehdi; Khalkhali, Hamid Reza

    2016-01-01

    Introduction For accurate dose calculations, it is necessary to provide a correct relationship between the CT numbers and electron density in radiotherapy treatment planning systems (TPSs). The purpose of this study was to investigate the energy dependence of measured CT numbers on substituted materials used for CT number calibration of radiotherapy TPSs and the resulting errors in the treatment planning calculation doses. Materials and Methods In this study, we designed a cylindrical water phantom with different materials used as tissue equivalent materials for the simulation of tissues and obtaining the related CT numbers. For evaluating the effect of CT number variations of substituted materials due to energy changing of scanner (kVp) on the dose calculation of TPS, the slices of the scanned phantom at three kVp's were imported into the desired TPSs (MIRS and CorePLAN). Dose calculations were performed on two TPSs. Results The mean absolute percentage differences between the CT numbers of CT scanner and two treatment planning systems for all the samples were 3.22%±2.57% for CorePLAN and 2.88%±2.11% for MIRS. It was also found that the maximum absolute percentage difference between all of the calculated doses from each photon beam of linac (6 and 15 MV) at three kVp's was less than 1.2%. Discussion The present study revealed that, for the materials with effective low atomic number, the mean CT number increased with increasing energy, which was opposite for the materials with an effective high atomic number. We concluded that the tissue substitute materials had a different behavior in the energy ranges from 80 to 130 kVp. So, it is necessary to consider the energy dependence of the substitute materials used for the measurement or calibration of CT number for radiotherapy treatment planning systems. PMID:27391672

  14. Observations of molecular hydrogen mixing ratio and stable isotopic composition at the Cabauw tall tower in the Netherlands

    NASA Astrophysics Data System (ADS)

    Batenburg, A. M.; Popa, M. E.; Vermeulen, A. T.; van den Bulk, W. C. M.; Jongejan, P. A. C.; Fisher, R. E.; Lowry, D.; Nisbet, E. G.; Röckmann, T.

    2016-12-01

    Measurements of the stable isotopic composition (δD(H2) or δD) of atmospheric molecular hydrogen (H2) are a useful addition to mixing ratio (χ(H2)) measurements for understanding the atmospheric H2 cycle. δD datasets published so far consist mostly of observations at background locations. We complement these with observations from the Cabauw tall tower at the CESAR site, situated in a densely populated region of the Netherlands. Our measurements show a large anthropogenic influence on the local H2 cycle, with frequently occurring pollution events that are characterized by χ(H2) values that reach up to ≈1 ppm and low δD values. An isotopic source signature analysis yields an apparent source signature below -400‰, which is much more D-depleted than the fossil fuel combustion source signature commonly used in H2 budget studies. Two diurnal cycles that were sampled at a suburban site near London also show a more D-depleted source signature (≈-340‰), though not as extremely depleted as at Cabauw. The source signature of the Northwest European vehicle fleet may have shifted to somewhat lower values due to changes in vehicle technology and driving conditions. Even so, the surprisingly depleted apparent source signature at Cabauw requires additional explanation; microbial H2 production seems the most likely cause. The Cabauw tower site also allowed us to sample vertical profiles. We found no decrease in χ(H2) at lower sampling levels (20 and 60 m) with respect to higher sampling levels (120 and 200 m). There was a significant shift to lower median δD values at the lower levels. This confirms the limited role of soil uptake around Cabauw, and again points to microbial H2 production during an extended growing season, as well as to possible differences in average fossil fuel combustion source signature between the different footprint areas of the sampling levels. So, although knowledge of the background cycle of H2 has improved over the last decade, surprising

  15. The solar wind interaction with Mars: Consideration of Phobos 2 mission observation of an ion composition boundary on the dayside

    SciTech Connect

    Breus, T.K.; Dubinin, E.M.; Barabash, S.V. Mitnitskii, V.Ya.; Pissarenko, N.F. ); Krymskii, A.M. ); Lundin, R. ); Luhmann, J.G. ); Yeroshenko, Ye.G.

    1991-07-01

    This paper describes the features of the boundary in the plasma ion composition near Mars which separates the region dominated by the solar wind protons from the plasma of planetary origin. This boundary was detected by the ASPERA experiment on Phobos 2. It is argued that the features of this boundary seem to be similar to those of other composition boundaries detected elsewhere: the cometopause near comet Halley, and a boundary in the ion composition which appears near Venus during periods of high solar wind dynamic pressure. Numerical modeling of the solar wind interaction with Mars supports the idea that during solar maximum the interaction of the Martian neutral atmosphere with the solar wind can result in a composition transition from solar wind to planetary ions in the low-altitude magnetosheath. This transition occurs because of charge exchange of solar wind protons with the neutral atmosphere and photoionization.

  16. Energy dependence of the spin excitation anisotropy in uniaxial-strained BaFe1.9Ni0.1As2

    DOE PAGES

    Song, Yu; Lu, Xingye; Abernathy, Douglas L.; ...

    2015-11-06

    In this study, we use inelastic neutron scattering to study the temperature and energy dependence of the spin excitation anisotropy in uniaxial-strained electron-doped iron pnictide BaFe1.9Ni0.1As2 near optimal superconductivity (Tc = 20K). Our work has been motivated by the observation of in-plane resistivity anisotropy in the paramagnetic tetragonal phase of electron-underdoped iron pnictides under uniaxial pressure, which has been attributed to a spin-driven Ising-nematic state or orbital ordering. Here we show that the spin excitation anisotropy, a signature of the spin-driven Ising-nematic phase, exists for energies below 60 meV in uniaxial-strained BaFe1.9Ni0.1As2. Since this energy scale is considerably larger thanmore » the energy splitting of the dxz and dyz bands of uniaxial-strained Ba(Fe1–xCox)2As2 near optimal superconductivity, spin Ising-nematic correlations are likely the driving force for the resistivity anisotropy and associated electronic nematic correlations.« less

  17. Beam-energy-dependent two-pion interferometry and the freeze-out eccentricity of pions measured in heavy ion collisions at the STAR detector

    SciTech Connect

    Adamczyk, L.

    2015-07-10

    In this study, we present results of analyses of two-pion interferometry in Au+Au collisions at √sNN = 7.7, 11.5, 19.6, 27, 39, 62.4, and 200 GeV measured in the STAR detector as part of the RHIC Beam Energy Scan program. The extracted correlation lengths (HBT radii) are studied as a function of beam energy, azimuthal angle relative to the reaction plane, centrality, and transverse mass (mT) of the particles. The azimuthal analysis allows extraction of the eccentricity of the entire fireball at kinetic freeze-out. The energy dependence of this observable is expected to be sensitive to changes in the equation of state. A new global fit method is studied as an alternate method to directly measure the parameters in the azimuthal analysis. The eccentricity shows a monotonic decrease with beam energy that is qualitatively consistent with the trend from all model predictions and quantitatively consistent with a hadronic transport model.

  18. Energy dependence of Kπ, pπ and Kp fluctuations in Au+Au collisions from √sNN=7.7 to 200 GeV

    DOE PAGES

    Adamczyk, L.

    2015-08-07

    A search for the quantum chromodynamics (QCD) critical point was performed by the STAR experiment at the Relativistic Heavy Ion Collider, using dynamical fluctuations of unlike particle pairs. Heavy ion collisions were studied over a large range of collision energies with homogeneous acceptance and excellent particle identification, covering a significant range in the QCD phase diagram where a critical point may be located. Dynamical Kπ, pπ, and Kp fluctuations as measured by the STAR experiment in central 0–5% Au+Au collisions from center-of-mass collision energies √sNN=7.7 to 200 GeV are presented. The observable νdyn was used to quantify the magnitude ofmore » the dynamical fluctuations in event-by-event measurements of the Kπ, pπ, and Kp pairs. The energy dependences of these fluctuations from central 0–5% Au+Au collisions all demonstrate a smooth evolution with collision energy.« less

  19. Beam-energy-dependent two-pion interferometry and the freeze-out eccentricity of pions measured in heavy ion collisions at the STAR detector

    DOE PAGES

    Adamczyk, L.

    2015-07-10

    In this study, we present results of analyses of two-pion interferometry in Au+Au collisions at √sNN = 7.7, 11.5, 19.6, 27, 39, 62.4, and 200 GeV measured in the STAR detector as part of the RHIC Beam Energy Scan program. The extracted correlation lengths (HBT radii) are studied as a function of beam energy, azimuthal angle relative to the reaction plane, centrality, and transverse mass (mT) of the particles. The azimuthal analysis allows extraction of the eccentricity of the entire fireball at kinetic freeze-out. The energy dependence of this observable is expected to be sensitive to changes in the equationmore » of state. A new global fit method is studied as an alternate method to directly measure the parameters in the azimuthal analysis. The eccentricity shows a monotonic decrease with beam energy that is qualitatively consistent with the trend from all model predictions and quantitatively consistent with a hadronic transport model.« less

  20. Beam-energy-dependent two-pion interferometry and the freeze-out eccentricity of pions measured in heavy ion collisions at the STAR detector

    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.; Kosarzewski, L. K.; 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.; Poniatowska, K.; 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.; 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

    2015-07-01

    We present results of analyses of two-pion interferometry in Au +Au collisions at √{sNN}=7.7 , 11.5, 19.6, 27, 39, 62.4, and 200 GeV measured in the STAR detector as part of the BNL Relativistic Heavy Ion Collider Beam Energy Scan program. The extracted correlation lengths (Hanbury-Brown-Twiss radii) are studied as a function of beam energy, azimuthal angle relative to the reaction plane, centrality, and transverse mass (mT) of the particles. The azimuthal analysis allows extraction of the eccentricity of the entire fireball at kinetic freeze-out. The energy dependence of this observable is expected to be sensitive to changes in the equation of state. A new global fit method is studied as an alternate method to directly measure the parameters in the azimuthal analysis. The eccentricity shows a monotonic decrease with beam energy that is qualitatively consistent with the trend from all model predictions and quantitatively consistent with a hadronic transport model.

  1. Net electron-phonon scattering rates in InN/GaN multiple quantum wells: The effects of an energy dependent acoustic deformation potential

    SciTech Connect

    Xia, H. Patterson, R.; Feng, Y.; Shrestha, S.; Conibeer, G.

    2014-08-11

    The rates of charge carrier relaxation by phonon emission are of substantial importance in the field of hot carrier solar cell, primarily in investigation of mechanisms to slow down hot carrier cooling. In this work, energy and momentum resolved deformation potentials relevant to electron-phonon scattering are computed for wurtzite InN and GaN as well as an InN/GaN multiple quantum well (MQW) superlattice using ab-initio methods. These deformation potentials reveal important features such as discontinuities across the electronic bandgap of the materials and variations over tens of eV. The energy dependence of the deformation potential is found to be very similar for wurtzite nitrides despite differences between the In and Ga pseudopotentials and their corresponding electronic band structures. Charge carrier relaxation by this mechanism is expected to be minimal for electrons within a few eV of the conduction band edge. However, hole scattering at energies more accessible to excitation by solar radiation is possible between heavy and light hole states. Moderate reductions in overall scattering rates are observed in MQW relative to the bulk nitride materials.

  2. Composition of inner-source heavy pickup ions at 1 AU: SOHO/CELIAS/CTOF observations. Implications for the production mechanisms

    NASA Astrophysics Data System (ADS)

    Taut, A.; Berger, L.; Drews, C.; Wimmer-Schweingruber, R. F.

    2015-04-01

    Context. Pickup ions in the inner heliosphere mainly originate in two sources, one interstellar and one in the inner solar system. In contrast to the interstellar source that is comparatively well understood, the nature of the inner source has not been clearly identified. Former results obtained with the Solar Wind Ion Composition Spectrometer on-board the Ulysses spacecraft revealed that the composition of inner-source pickup ions is similar, but not equal, to the elemental solar-wind composition. These observations suffered from very low counting statistics of roughly one C+ count per day. Aims: Because the composition of inner-source pickup ions could lead to identifying their origin, we used data from the Charge-Time-Of-Flight sensor on-board the Solar and Heliospheric Observatory. It offers a large geometry factor that results in about 100 C+ counts per day combined with an excellent mass-per-charge resolution. These features enable a precise determination of the inner-source heavy pickup ion composition at 1 AU. To address the production mechanisms of inner-source pickup ions, we set up a toy model based on the production scenario involving the passage of solar-wind ions through thin dust grains to explain the observed deviations of the inner-source PUI and the elemental solar-wind composition. Methods: An in-flight calibration of the sensor allows identification of heavy pickup ions from pulse height analysis data by their mass-per-charge. A statistical analysis was performed to derive the inner-source heavy pickup ion relative abundances of N+, O+, Ne+, Mg+, Mg2+, and Si+ compared to C+. Results: Our results for the inner-source pickup ion composition are in good agreement with previous studies and confirm the deviations from the solar-wind composition. The large geometry factor of the Charge-Time-of-Flight sensor even allowed the abundance ratios of the two most prominent pickup ions, C+ and O+, to be investigated at varying solar-wind speeds. We found

  3. Submicron aerosol and trace gas composition near Manaus as observed during GoAmazon2014/5

    NASA Astrophysics Data System (ADS)

    Ferreira De Brito, J.; Wurm, F.; Liu, Y.; de Sá, S. S.; Carbone, S.; Rizzo, L. V.; Cirino, G. G.; Barbosa, H. M.; Souza, R. A. F. D.; Martin, S. T.; Artaxo, P.

    2014-12-01

    The Amazon Basin, during the wet season, has one of the lowest aerosol concentrations worldwide, with air masses covering thousands of kilometers of pristine forest with negligible human impact. The atmosphere in such regions is strongly coupled with the biosphere through primary biological aerosols, biogenic salts and secondary aerosols from oxidation of biogenic VOCs. The natural environment is strongly modified nearby urbanized areas, in particular Manaus, a city of nearly two million people. The urban pollution plume has high concentrations of oxides of nitrogen and sulfur, carbon monoxide, particle concentrations, and soot, among other pollutants, strongly contrasting with the clean air masses reaching the city. Such unique location provides the ideal laboratory to study the isolated urban emission, as well the pristine environment by perturbing it in a relatively known fashion. The GoAmazon experiment was designed with these questions in mind, combining remote sensing, in situand airborne measurements. This manuscript describes the measurements currently taking place at the T2 site, near Manaus, frequently impacted by relatively fresh emissions from the city. This presentation focuses on aerosol properties and trace gas composition at the T2 site. PM1 mass concentration from March up to July 2014 has been observed to be dominated by organics (1.51 μg m-3), followed by BC (0.83 μg m-3), SO4 (0.17 μg m-3), NO3 (0.08 μg m-3) and NH4 (0.06 μg m-3). Mean aerosol number concentration was 3600 cm-3, with a mean geometric diameter of 70 nm. As for the trace gases, initial estimates of isoprene average ambient concentration is 0.95 ppb, whereas MVK+MACR has been estimated to be 0.76 ppb. Average mixing ratios of toluene, benzene and C8 aromatics were 0.31 ppb, 0.16 ppb and 0.15 ppb, respectively, correlating relatively well with markers of anthropogenic activities, such as BC. Such measurements will carry on throughout GoAmazon 2014/5, providing a unique dataset

  4. Structure and composition of the Southern Mariana Forearc: new observations and samples from Shinkai 6500 dive studies in 2010

    NASA Astrophysics Data System (ADS)

    Ohara, Y.; Reagan, M. K.; Ishizuka, O.; Stern, R. J.

    2010-12-01

    The 3000-km long Izu-Bonin-Mariana (IBM) Arc system is an outstanding example of an intraoceanic convergent plate margin, and has become the particular focus of Japanese and US efforts to understand the operation of the “Subduction Factory”. In 2006 and 2008, twelve DSV Shinkai 6500 dives (973-977 and 1091-1097) were performed during YK06-12 and YK08-08 Leg 2 cruises along the landward slope of the southern Mariana Trench. The goal was to sample the remaining early arc crust associated with subduction initiation in the IBM system and upper mantle exposed in the forearc in order to gain a clearer understanding of the structure and evolution of Mariana forearc crust and upper mantle. The fruitful results include the recovery of the entire suite of rocks associated with what could be termed a “supra-subduction zone ophiolite” that formed during subduction initiation. An important discovery is that MORB-like tholeiitic basalts crop out over large areas. These “fore-arc basalts” (FAB) underlie boninites and overlie diabasic and gabbroic rocks. Potential origins include eruption at a spreading center before subduction began or eruption during near-trench spreading after subduction began (Reagan et al., 2010, G3). Another important discovery is a region of active forearc rifting at the southern end of the Mariana arc, named SE Mariana Forearc Rift (SEMFR). The SEMFR was firstly mapped with HMR-1 sonar (Martinez et al., 2000, JGR). Two dives at SEMFR recovered less-depleted backarc related peridotites (at Dive 973; Michibayashi et al., 2009, G3), and fresh basalts and basaltic andesites with petrographic characteristics like backarc basin lavas (at Dive 1096; see Ribeiro et al., AGU FM 2010). Although our previous studies have produced a number of important new observations about the geology of the southern Mariana forearc, our understanding of the region is still primitive. We will be conducting another cruise (YK10-12) during late September, 2010 to tackle

  5. The discovery and modeling of energy dependent time-lags and fractional RMS of heartbeat state in GRS 1915+105

    NASA Astrophysics Data System (ADS)

    Mir, Mubashir; Iqbal, Naseer; Pahari, Mayukh; Misra, Ranjeev

    2016-07-01

    We report the discovery and modeling of enigmatic Energy dependent time-lags and fractional RMS of the heartbeat state in GRS 1915+105. The time-lags reveal the crucial information related to geometry of accretion flow, the emission regions and the relation between various spectral parameters. The lag and frms at the fundamental frequency show non-monotonic behavior with energy. The lag increases up to typically ˜10 keV and later shows a reversal and in some observations becomes hard(negative). However, the lags at the harmonic increase with energy and don't show any turn around at least till ˜20 keV. The frms at harmonic has similar non-monotonic behavior as at fundamental, however the variability amplitude is lesser as expected. The lag seen here can have magnitude of the order of seconds, and thus can't be accounted by light travel time effects or comptonization delays. The continuum X-ray spectra can roughly be described by a disk blackbody and a hard X-ray power-law component and from phase resolved spectroscopy it has been shown that the inner disk radius varies during the oscillation We propose the model based on the delayed response of inner disc (DRIOD) radius to the outer accretion rate i;e r_{in}(t)∝ dot{m}^β (t-τ_d). The fluctuating accretion rate varies the inner disk after a certain time delay t_d which could be of the order of the viscous propagation delays. The model very well explains the observed shape and nature of lags and frms at fundamental and harmonic frequencies. We present here the series of observations that constrain the four free parameters of our model. These parameters contain the vital information related to the nature of accretion flow in a highly periodic state like a heartbeat state.

  6. Solar Ion Processing of Major Element Surface Compositions of Mature Mare Soils: Insights from Combined XPS and Analytical TEM Observations

    NASA Technical Reports Server (NTRS)

    Christoffersen, R.; Dukes, C.; Keller, L. P.; Baragiola, R.

    2012-01-01

    Solar wind ions are capable of altering the sur-face chemistry of the lunar regolith by a number of mechanisms including preferential sputtering, radiation-enhanced diffusion and sputter erosion of space weathered surfaces containing pre-existing compositional profiles. We have previously reported in-situ ion irradiation experiments supported by X-ray photoelectron spectroscopy (XPS) and analytical TEM that show how solar ions potentially drive Fe and Ti reduction at the monolayer scale as well as the 10-100 nm depth scale in lunar soils [1]. Here we report experimental data on the effect of ion irradiation on the major element surface composition in a mature mare soil.

  7. Compositional trends of γ-induced optical changes observed in chalcogenide glasses of binary As-S system

    SciTech Connect

    Shpotyuk, M.; Shpotyuk, O.; Golovchak, Roman; McCloy, John S.; Riley, Brian J.

    2014-01-23

    Compositional trends of γ-induced optical changes in chalcogenide glasses are studied with the binary As-S system. Effects of γ-irradiation and annealing are compared using the changes measured in the fundamental optical absorption edge region. It is shown that annealing near the glass transition temperature leads to bleaching of As-S glasses, while γ-irradiation leads to darkening; both depend on the glass composition and thermal history of the specimens. These results are explained in terms of competitive destruction–polymerization transformations and physical aging occurring in As-S chalcogenide glasses under the influence of γ-irradiation.

  8. Energy Dependence of Moments of Net-Proton, Net-Kaon, and Net-Charge Multiplicity Distributions at STAR

    NASA Astrophysics Data System (ADS)

    Xu, Ji

    2016-08-01

    One of the main goals of the RHIC Beam Energy Scan (BES) program is to study the QCD phase structure, which includes the search for the QCD critical point, over a wide range of chemical potential (μB). Theoretical calculations predict that fluctuations of conserved quantities, such as baryon number (B), charge (Q), and strangeness (S), are sensitive to the correlation length of the dynamical system. Experimentally, higher moments of multiplicity distributions have been utilized to search for the QCD critical point in heavy-ion collisions. In this paper, we report recent efficiency-corrected cumulants and cumulants ratios of the net- proton, net-kaon, and net-charge multiplicity distributions in Au+Au collisions at √sNN = 7.7, 11.5, 14.5, 19.6, 27, 39, 62.4, and 200 GeV collected in the years 2010, 2011, and 2014 with STAR at RHIC. The centrality and energy dependence of the cumulants up to the fourth order, as well as their ratios, are presented. Furthermore, the comparisons with baseline calculations (Poisson) and non-critical-point models (UrQMD) will also be discussed.

  9. Temperature- and energy-dependent phase shifts of resonant multiple-beam X-ray diffraction in germanium crystals.

    PubMed

    Liao, Po-Yu; Liu, Wen-Chung; Cheng, Chih-Hao; Chiu, Yi-Hua; Kung, Ying-Yu; Chang, Shih-Lin

    2015-07-01

    This paper reports temperature- and energy-dependent phase shifts of resonant multiple-beam X-ray diffraction in germanium crystals, involving forbidden (002) and weak (222) reflections. Phase determination based on multiple-beam diffraction is employed to estimate phase shifts from (002)-based {(002)(375)(373̅)} four-beam cases and (222)-based { (222)(5̅33̅)} three-beam cases in the vicinity of the Ge K edge for temperatures from 20 K up to 300 K. The forbidden/weak reflections enhance the sensitivity of measuring phases at resonance. At room temperature, the resonance triplet phases reach a maximum of 8° for the four-beam cases and -19° for the three-beam cases. It is found that the peak intensities and triplet phases obtained from the (002) four-beam diffraction are related to thermal motion induced anisotropy and anomalous dispersion, while the (222) three-beam diffraction depends on the aspherical covalent electron distribution and anomalous dispersion. However, the electron-phonon interaction usually affects the forbidden reflections with increasing temperatures and seems to have less effect on the resonance triplet phase shifts measured from the (002) four-beam diffraction. The resonance triplet phase shifts of the (222) three-beam diffraction versus temperature are also small.

  10. Determination of the energy dependence of the BC-408 plastic scintillation detector in medium energy x-ray beams

    NASA Astrophysics Data System (ADS)

    Yücel, H.; Çubukçu, Ş.; Uyar, E.; Engin, Y.

    2014-11-01

    The energy dependence of the response of BC-408 plastic scintillator (PS), an approximately water-equivalent material, has been investigated by employing standardized x-ray beams. IEC RQA and ISO N series x-ray beam qualities, in the range of 40-100 kVp, were calibrated using a PTW-type ionization chamber. The energy response of a thick BC-408 PS detector was measured using the multichannel pulse height analysis method. The response of BC-408 PS increased gradually with increasing energy in the energy range of 40-80 kVp and then showed a flat behavior at about 80 to 120 kVp. This might be due to the self-attenuation of scintillation light by the scintillator itself and may also be partly due to the ionization quenching, leading to a reduction in the intensity of the light output from the scintillator. The results indicated that the sensitivity drop in BC-408 PS material at lower photon energies may be overcome by adding some high-Z elements to its polyvinyltoluene (PVT) base. The material modification may compensate for the drop in the response at lower photon energies. Thus plastic scintillation dosimetry is potentially suitable for applications in diagnostic radiology.

  11. The energy dependence of the lateral dose response functions of detectors with various densities in photon-beam dosimetry

    NASA Astrophysics Data System (ADS)

    Khee Looe, Hui; Harder, Dietrich; Poppe, Björn

    2017-02-01

    The lateral dose response function is a general characteristic of the volume effect of a detector used for photon dosimetry in a water phantom. It serves as the convolution kernel transforming the true absorbed dose to water profile, which would be produced within the undisturbed water phantom, into the detector-measured signal profile. The shape of the lateral dose response function characterizes (i) the volume averaging attributable to the detector’s size and (ii) the disturbance of the secondary electron field associated with the deviation of the electron density of the detector material from the surrounding water. In previous work, the characteristic dependence of the shape of the lateral dose response function upon the electron density of the detector material was studied for 6 MV photons by Monte Carlo simulation of a wall-less voxel-sized detector (Looe et al 2015 Phys. Med. Biol. 60 6585-07). This study is here continued for 60Co gamma rays and 15 MV photons in comparison with 6 MV photons. It is found (1) that throughout these photon spectra the shapes of the lateral dose response functions are retaining their characteristic dependence on the detector’s electron density, and (2) that their energy-dependent changes are only moderate. This appears as a practical advantage because the lateral dose response function can then be treated as practically invariant across a clinical photon beam in spite of the known changes of the photon spectrum with increasing distance from the beam axis.

  12. Ethylene Regulates Energy-Dependent Non-Photochemical Quenching in Arabidopsis through Repression of the Xanthophyll Cycle

    PubMed Central

    Chen, Zhong; Gallie, Daniel R.

    2015-01-01

    Energy-dependent (qE) non-photochemical quenching (NPQ) thermally dissipates excess absorbed light energy as a protective mechanism to prevent the over reduction of photosystem II and the generation of reactive oxygen species (ROS). The xanthophyll cycle, induced when the level of absorbed light energy exceeds the capacity of photochemistry, contributes to qE. In this work, we show that ethylene regulates the xanthophyll cycle in Arabidopsis. Analysis of eto1-1, exhibiting increased ethylene production, and ctr1-3, exhibiting constitutive ethylene response, revealed defects in NPQ resulting from impaired de-epoxidation of violaxanthin by violaxanthin de-epoxidase (VDE) encoded by NPQ1. Elevated ethylene signaling reduced the level of active VDE through decreased NPQ1 promoter activity and impaired VDE activation resulting from a lower transthylakoid membrane pH gradient. Increasing the concentration of CO2 partially corrected the ethylene-mediated defects in NPQ and photosynthesis, indicating that changes in ethylene signaling affect stromal CO2 solubility. Increasing VDE expression in eto1-1 and ctr1-3 restored light-activated de-epoxidation and qE, reduced superoxide production and reduced photoinhibition. Restoring VDE activity significantly reversed the small growth phenotype of eto1-1 and ctr1-3 without altering ethylene production or ethylene responses. Our results demonstrate that ethylene increases ROS production and photosensitivity in response to high light and the associated reduced plant stature is partially reversed by increasing VDE activity. PMID:26630486

  13. Energy-dependent Orbital Modulation of X-rays and Constraints on Emission of the Jet in Cyg X-3

    NASA Technical Reports Server (NTRS)

    Zdziarski, Andrzej A.; Maitra, Chandreyee; Frankowski, Adam; Skinner, Gerald K.; Misra, Ranjeev

    2012-01-01

    We study orbital modulation of X-rays from Cyg X-3, using data from Swift, INTEGRAL and RXTE. Using the wealth of the presently available data and an improved averaging method, we obtain energy-dependent folded and averaged light curves with unprecedented accuracy. We find that above 5 keV, the modulation depth decreases with the increasing energy, which is consistent with the modulation being caused by both bound-free absorption and Compton scattering in the stellar wind of the donor, with minima corresponding to the highest optical depth, which occurs around the superior conjunction. We find a decrease of the depth below 3 keV, which appears to be due to re-emission of the absorbed continuum by the wind in soft X-ray lines. Based on the shape of the folded light curves, any X-ray contribution from the jet in Cyg X-3, which emits ?-rays detected at energies > 0.1 GeV in soft spectral states, is found to be minor up to 100 keV. This implies the presence of a rather sharp low-energy break in the jet MeV-range spectrum.We also calculate phase-resolved RXTE X-ray spectra, and show the difference between the spectra corresponding to phases around the superior and inferior conjunctions can indeed be accounted for by a combined effect of bound-free absorption in an ionized medium and Compton scattering.

  14. Ethylene Regulates Energy-Dependent Non-Photochemical Quenching in Arabidopsis through Repression of the Xanthophyll Cycle.

    PubMed

    Chen, Zhong; Gallie, Daniel R

    2015-01-01

    Energy-dependent (qE) non-photochemical quenching (NPQ) thermally dissipates excess absorbed light energy as a protective mechanism to prevent the over reduction of photosystem II and the generation of reactive oxygen species (ROS). The xanthophyll cycle, induced when the level of absorbed light energy exceeds the capacity of photochemistry, contributes to qE. In this work, we show that ethylene regulates the xanthophyll cycle in Arabidopsis. Analysis of eto1-1, exhibiting increased ethylene production, and ctr1-3, exhibiting constitutive ethylene response, revealed defects in NPQ resulting from impaired de-epoxidation of violaxanthin by violaxanthin de-epoxidase (VDE) encoded by NPQ1. Elevated ethylene signaling reduced the level of active VDE through decreased NPQ1 promoter activity and impaired VDE activation resulting from a lower transthylakoid membrane pH gradient. Increasing the concentration of CO2 partially corrected the ethylene-mediated defects in NPQ and photosynthesis, indicating that changes in ethylene signaling affect stromal CO2 solubility. Increasing VDE expression in eto1-1 and ctr1-3 restored light-activated de-epoxidation and qE, reduced superoxide production and reduced photoinhibition. Restoring VDE activity significantly reversed the small growth phenotype of eto1-1 and ctr1-3 without altering ethylene production or ethylene responses. Our results demonstrate that ethylene increases ROS production and photosensitivity in response to high light and the associated reduced plant stature is partially reversed by increasing VDE activity.

  15. Energy-dependent dynamics of keV to MeV electrons in the inner zone, outer zone, and slot regions

    DOE PAGES

    Reeves, Geoffrey D.; Friedel, Reiner H. W.; Larsen, Brian A.; ...

    2016-01-28

    Here, we present observations of the radiation belts from the Helium Oxygen Proton Electron and Magnetic Electron Ion Spectrometer particle detectors on the Van Allen Probes satellites that illustrate the energy dependence and L shell dependence of radiation belt enhancements and decays. We survey events in 2013 and analyze an event on 1 March in more detail. The observations show the following: (a) at all L shells, lower energy electrons are enhanced more often than higher energies; (b) events that fill the slot region are more common at lower energies; (c) enhancements of electrons in the inner zone are moremore » common at lower energies; and (d) even when events do not fully fill the slot region, enhancements at lower energies tend to extend to lower L shells than higher energies. During enhancement events the outer zone extends to lower L shells at lower energies while being confined to higher L shells at higher energies. The inner zone shows the opposite with an outer boundary at higher L shells for lower energies. Both boundaries are nearly straight in log(energy) versus L shell space. At energies below a few 100 keV, radiation belt electron penetration through the slot region into the inner zone is commonplace, but the number and frequency of “slot filling” events decreases with increasing energy. The inner zone is enhanced only at energies that penetrate through the slot. Energy- and L shell-dependent losses (that are consistent with whistler hiss interactions) return the belts to more quiescent conditions.« less

  16. Experimental determination of the photon-energy dependent dose-to-water response of TLD600 and TLD700 (LiF:Mg,Ti) thermoluminescence detectors.

    PubMed

    Schwahofer, Andrea; Feist, Harald; Georg, Holger; Häring, Peter; Schlegel, Wolfgang

    2017-03-01

    The aim of this study has been the experimental determination of the energy dependent dose-to-water response of TLD600 and TLD700 thermoluminescent detectors (Harshaw) in X-ray beams with mean photon energies from about 20 to 200keV in comparison with (60)Co gamma rays and 6MV X-rays. Experiments were carried out in collaboration with the German secondary standard laboratory PTW Freiburg. The energy dependent relative responses of TLD600 and TLD700 thermoluminescence detectors were determined at radiation qualities between 30kVp and 280kVp. The overall uncertainty of the measured values was characterized by standard deviations varying from 1.2 to 3%. The present results agree with previous studies on the energy dependent dose-to-water response of TLD100. As an application example, the results were used to measure doses associated with X-ray imaging in image-guided radiotherapy.

  17. Photon energy dependence of photo-induced inverse spin-Hall effect in Pt/GaAs and Pt/Ge

    SciTech Connect

    Isella, Giovanni Bottegoni, Federico; Ferrari, Alberto; Finazzi, Marco; Ciccacci, Franco

    2015-06-08

    We report the photon energy dependence of photo-induced inverse spin Hall effect (ISHE) in Pt/GaAs and Pt/Ge Schottky junctions. The experimental results are compared with a spin drift-diffusion model, which highlights the role played by the different spin lifetime in the two semiconductors, in determining the energy dependence of the ISHE signal detected in the Pt layer. The good qualitative agreement between experiments and modelling indicates that photo-induced ISHE can be used as a tool to characterize spin lifetime in semiconductors.

  18. Protective effect of vitamin E on cypermethrin-induced follicular atresia in rat ovary: Evidence for energy dependent mechanism

    PubMed Central

    Molavi, Morteza; Razi, Mazdak; Cheraghi, Hadi; Khorramjouy, Mona; Ostadi, Araz; Gholirad, Safa

    2016-01-01

    It has been shown that chronic exposure to cypermethrin (CPM), a pyrethroid pesticide, results in follicular atresia via pathologically affecting angiogenesis, disrupting endocrine potential and enhancing oxidative stress. This study was aimed to uncover the CPM-exposed energy dependent follicular cells apoptosis and to estimate protective effect of vitamin E (VitE) as a potent antioxidant. Thirty six Wistar rats were divided into six groups (n = 6 rats for each group) including; control-sham, CPM-received (CPM, 75 mg kg-1, intraperitoneally), and CPM and VitE-treated (VitE, 150 mg kg-1, orally) for 14 and 24 days. The protein biosynthesis of glucose transporter-1 (GLUT-1) and caspase-3 in follicles were estimated by using immuno-histochemical staining at preantral and antral stages. Moreover, the periodic acid Schiff (PAS) staining was performed in order to evaluate the intracytoplasmic carbohydrate ratio in follicular cells and oocyte. Percentages of follicles with GLUT-1, Caspase-3 and PAS-positive cells were compared between groups. Immunohistochemical analyses showed that, VitE significantly up-regulated the GLUT-1 expression and improved the intracytoplasmic carbohydrate supplementation especially at preantral follicles. The cross sections from the CPM-exposed ovaries represented remarkable elevation in percentage of atretic preantral and antral follicles with caspase-3 biosynthesis, which was remarkably (p < 0.05) diminished in VitE co-treated groups. In conclusion, our data showed that VitE by up-regulating of the GLUT-1 biosynthesis improved glucose uptake at follicular cells and oocyte levels that in turn inhibited pro-apoptotic protein caspase-3 biosynthesis. PMID:27482357

  19. 3D position of radiation sources using an automated gamma camera and ML algorithm with energy-dependent response functions

    NASA Astrophysics Data System (ADS)

    Lee, Wonho; Wehe, David

    2004-09-01

    Portable γ-ray imaging systems operating from 100keV to 3MeV are used in nuclear medicine, astrophysics and industrial applications. 2D images of γ-rays are common in many fields using radiation-detection systems (Appl. Opt. 17 (3) (1978) 337; IEEE Trans. Nucl. Sci. Ns- 31 (1984) 771; IEEE Trans. Nucl. Sci. NS- 44 (3) (1997) 911). In this work, the 3D position of a radiation source is determined by a portable gamma-ray imaging system. 2D gamma-ray images were obtained from different positions of the gamma camera and the third dimension, the distance between the detector and the radiation source, was calculated using triangulation. The imaging system consists of a 4×4 array of CsI(Tl) detectors coupled to photodiode detectors that are mounted on an automated table which can precisely position the angular axis of the camera. Lead shields the detector array from the background radiation. Additionally, a CCD camera is attached to the top of the gamma camera and provides coincident 2D visual information. The inferred distances from the center of the two measurement points and a radiation source had less than a 3% error within a range of 3m. The radiation image from the gamma camera and the visual image from CCD camera are superimposed into one combined image using a maximum-likelihood (ML) algorithm to make the image more precise. The response functions for the ML algorithm depend on the energy of incident radiation, and are obtained from both experiments and simulations. The energy-dependent response functions are shown to yield better imaging performance compared with the fixed energy response function commonly used previously.

  20. Effects of intrinsic degrees of freedom in enhancement of sub-barrier fusion excitation function data and energy-dependent one-dimensional barrier penetration model

    NASA Astrophysics Data System (ADS)

    Gautam, M. S.

    2016-03-01

    We have analyzed the role of barrier modification effects (barrier height, barrier position, barrier curvature) introduced due to the energy-dependent Woods-Saxon potential model (EDWSP model) and the coupled channel model on the sub-barrier fusion dynamics of {}_{16}^{32,36} {{S}} + {}_{40}^{90,96} {{Zr}} reactions. The influence of inelastic surface excitations of colliding pairs and multi-neutron transfer channels is found to be a dominant mode of couplings. The coupling of relative motion of colliding nuclei to these dominant intrinsic degrees of freedom leads to a substantially large fusion enhancement at below-barrier energies over the expectations of one-dimensional barrier penetration model. The coupled channel calculations based upon static Woods-Saxon potential must include the internal nuclear structure degrees of freedom of colliding nuclei for complete description of experimental data. On the other hand, theoretical calculations based upon the EDWSP model along with Wong formula provide a complete description of sub-barrier fusion enhancement of various heavy-ion fusion reactions. In EDWSP model calculations, significantly larger values of diffuseness parameter ranging from a = 0.98 fm to a = 0.85 fm are required to address the observed sub-barrier fusion enhancement of {}_{16}^{32,36} {{S}} + {}_{40}^{90,96} {{Zr}} reactions. Furthermore, within the context of EDWSP model, it is possible to achieve an agreement with the experimental fusion cross-sectional data within 10 %. For four heavy-ion fusion reactions, only at 4 fusion data points out of 90 fusion data points deviates exceeding 5 %, while 86 fusion data points lie within 5 % and hence the EDWSP model is able to account the above-barrier portion of the fusion cross-sectional data within 5 % with a probability greater than 90 %.

  1. Interstellar neutral flow characteristics, composition, and interaction with the heliosphere - neutral gas and pickup ion analysis from ongoing observations and perspectives for IMAP

    NASA Astrophysics Data System (ADS)

    Moebius, E.; Bzowski, M.; Drews, C.; Frisch, P. C.; Fuselier, S. A.; Galli, A.; Gloeckler, G.; Kubiak, M. A.; Kucharek, H.; Lee, M. A.; Leonard, T.; McComas, D. J.; Park, J.; Schwadron, N.; Swaczyna, P.; Sokol, J. M.; Wood, B. E.; Wurz, P.

    2015-12-01

    The Sun's motion relative to the surrounding interstellar medium leads to an interstellar neutral (ISN) wind through the heliosphere that is moderately depleted by ionization. This situation allows remote sensing of the ISN through resonant scattering of solar UV and in-situ sampling, first via pickup ions (PUI) and most recently with direct neutral atom imaging. PUI observations have revealed the gravitational focusing cone of interstellar He and Ne as well as the composition of high ionization potential elements. After the first direct ISN He observations with Ulysses GAS, the Interstellar Boundary Explorer (IBEX) observes with high collecting power the ISN flow trajectories very close to their perihelion in Earth's orbit for H, He, O, and Ne from December through March. Meanwhile, IBEX has recorded seven years of ISN observations, with changing solar activity and varying viewing strategies. These recurring and remarkably repeatable observations allow us to consolidate the derived physical parameters and some key compositional aspects of the interstellar medium. IBEX observations provide a very precise relation between ISN flow longitude and speed via the hyperbolic trajectory equation, but with larger uncertainties separately for longitude and speed. Recent concerted studies have led to a velocity vector that is consistent between IBEX and Ulysses, with a substantially higher temperature than found previously. The fact that the IBEX He and O ISN observations contain a substantial secondary neutral contribution adds complexity to the quantitative analysis of the physical interstellar medium parameters. However, their discovery also provides invaluable insight into the interstellar plasma interaction in the outer heliosheath, which is shaped strongly by the interstellar magnetic field. The longitude range of the IBEX observations limits the precision of the ISN velocity vector. The IBEX collection power and its sensitivity to the Earth's magnetosphere limit

  2. Europa's surface composition from near-infrared observations: A comparison of results from linear mixture modeling and radiative transfer modeling

    NASA Astrophysics Data System (ADS)

    Shirley, James H.; Jamieson, Corey S.; Dalton, J. Bradley

    2016-08-01

    Quantitative estimates of the abundance of surface materials and of water ice particle grain sizes at five widely separated locations on the surface of Europa have been obtained by two independent methods in order to search for possible discrepancies that may be attributed to differences in the methods employed. Results of radiative transfer (RT) compositional modeling (also known as intimate mixture modeling) from two prior studies are here employed without modification. Areal (or "checkerboard") mixture modeling, also known as linear mixture (LM) modeling, was performed to allow direct comparisons. The failure to model scattering processes (whose effects may be strongly nonlinear) in the LM approach is recognized as a potential source of errors. RT modeling accounts for nonlinear spectral responses due to scattering but is subject to other uncertainties. By comparing abundance estimates for H2SO4 · nH2O and water ice, obtained through both methods as applied to identical spectra, we may gain some insight into the importance of "volume scattering" effects for investigations of Europa's surface composition. We find that both methods return similar abundances for each location analyzed; linear correlation coefficients of ≥ 0.98 are found between the derived H2SO4 · nH2O and water ice abundances returned by both methods. We thus find no evidence of a significant influence of volume scattering on the compositional solutions obtained by LM modeling for these locations. Some differences in the results obtained for water ice grain sizes are attributed to the limited selection of candidate materials allowed in the RT investigations.

  3. The influence of air-sea exchange on the isotropic composition of oceanic carbon: Observations and modeling

    SciTech Connect

    Lynch-Stieglitz, J.; Broecker, W.S.; Fairbanks, R.G.

    1995-12-01

    Although the carbon isotropic composition of ocean waters after they leave the surface ocean is determined by biological cycling, air-sea exchange affects the carbon isotopic composition of surface waters in two ways. The equilibrium fractionation between oceanic and atmospheric carbon increases with decreasing temperature. In Southern Ocean Surface Waters this isotopic equilibrium enriches {delta}{sup 13}C relative to the {delta}{sup 13}C expected from uptake and release of carbon by biological processes alone. Similarly, surface waters in the subtropical gyres are depleted in {delta}{sup 13}C due to extensive air-sea exchange at warm temperatures. Countering the tendency toward isotopic equilibration with the atmosphere (a relatively slow process), are the effects of the equilibration of CO{sub 2} itself (a much faster process). In regions where there is a net transfer of isotopically light CO{sub 2} from the ocean to the atmosphere (e.g., the equator) surface waters become enriched in {sup 13}C, whereas in regions where isotopically light CO{sub 2} is entering the ocean (e.g., the North Atlantic) surface waters become depleted in {sup 13}C. A compilation of high quality oceanic {delta}{sup 13}C measurements along with experiments performed using a zonally averaged three-basin dynamic ocean model are used to explore these processes. 40 refs., 14 figs., 1 tab.

  4. Energy dependence and dose response of Gafchromic EBT2 film over a wide range of photon, electron, and proton beam energies

    SciTech Connect

    Arjomandy, Bijan; Tailor, Ramesh; Anand, Aman; Sahoo, Narayan; Gillin, Michael; Prado, Karl; Vicic, Milos

    2010-05-15

    Purpose: Since the Gafchromic film EBT has been recently replaced by the newer model EBT2, its characterization, especially energy dependence, has become critically important. The energy dependence of the dose response of Gafchromic EBT2 film is evaluated for a broad range of energies from different radiation sources used in radiation therapy. Methods: The beams used for this study comprised of kilovoltage x rays (75, 125, and 250 kVp), {sup 137}Cs gamma (662 KeV), {sup 60}Co gamma (1.17-1.33 MeV), megavoltage x rays (6 and 18 MV), electron beams (6 and 20 MeV), and proton beams (100 and 250 MeV). The film's response to each of the above energies was measured over the dose range of 0.4-10 Gy, which corresponds to optical densities ranging from 0.05 to 0.74 for the film reader used. Results: The energy dependence of EBT2 was found to be relatively small within measurement uncertainties (1{sigma}={+-}4.5%) for all energies and modalities. Conclusion: For relative and absolute dosimetry of radiation therapy beams, the weak energy dependence of the EBT2 makes it most suitable for clinical use compared to other films.

  5. Impact of spaceborne carbon monoxide observations from the S-5P platform on tropospheric composition analyses and forecasts

    NASA Astrophysics Data System (ADS)

    Abida, Rachid; Attié, Jean-Luc; El Amraoui, Laaziz; Ricaud, Philippe; Lahoz, William; Eskes, Henk; Segers, Arjo; Curier, Lyana; de Haan, Johan; Kujanpää, Jukka; Oude Nijhuis, Albert; Tamminen, Johanna; Timmermans, Renske; Veefkind, Pepijn

    2017-01-01

    We use the technique of Observing System Simulation Experiments (OSSEs) to quantify the impact of spaceborne carbon monoxide (CO) total column observations from the Sentinel-5 Precursor (S-5P) platform on tropospheric analyses and forecasts. We focus on Europe for the period of northern summer 2003, when there was a severe heat wave episode associated with extremely hot and dry weather conditions. We describe different elements of the OSSE: (i) the nature run (NR), i.e., the truth; (ii) the CO synthetic observations; (iii) the assimilation run (AR), where we assimilate the observations of interest; (iv) the control run (CR), in this study a free model run without assimilation; and (v) efforts to establish the fidelity of the OSSE results. Comparison of the results from AR and the CR, against the NR, shows that CO total column observations from S-5P provide a significant benefit (at the 99 % confidence level) at the surface, with the largest benefit occurring over land in regions far away from emission sources. Furthermore, the S-5P CO total column observations are able to capture phenomena such as the forest fires that occurred in Portugal during northern summer 2003. These results provide evidence of the benefit of S-5P observations for monitoring processes contributing to atmospheric pollution.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  7. Energy dependence measurement of small-type optically stimulated luminescence (OSL) dosimeter by means of characteristic X-rays induced with general diagnostic X-ray equipment.

    PubMed

    Takegami, Kazuki; Hayashi, Hiroaki; Okino, Hiroki; Kimoto, Natsumi; Maehata, Itsumi; Kanazawa, Yuki; Okazaki, Tohru; Hashizume, Takuya; Kobayashi, Ikuo

    2016-01-01

    For X-ray inspections by way of general X-ray equipment, it is important to measure an entrance-skin dose. Recently, a small optically stimulated luminescence (OSL) dosimeter was made commercially available by Landauer, Inc. The dosimeter does not interfere with the medical images; therefore, it is expected to be a convenient detector for measuring personal exposure doses. In an actual clinical situation, it is assumed that X-rays of different energies will be detected by a dosimeter. For evaluation of the exposure dose measured by a dosimeter, it is necessary to know the energy dependence of the dosimeter. Our aim in this study was to measure the energy dependence of the OSL dosimeter experimentally in the diagnostic X-ray region. Metal samples weighing several grams were irradiated and, in this way, characteristic X-rays having energies ranging from 8 to 85 keV were generated. Using these mono-energetic X-rays, the dosimeter was irradiated. Simultaneously, the fluence of the X-rays was determined with a CdTe detector. The energy-dependent efficiency of the dosimeter was derived from the measured value of the dosimeter and the fluence. Moreover, the energy-dependent efficiency was calculated by Monte-Carlo simulation. The efficiency obtained in the experiment was in good agreement with that of the simulation. In conclusion, our proposed method, in which characteristic X-rays are used, is valuable for measurement of the energy dependence of a small OSL dosimeter in the diagnostic X-ray region.

  8. HST-COS observations of AGNs. II. Extended survey of ultraviolet composite spectra from 159 active galactic nuclei

    SciTech Connect

    Stevans, Matthew L.; Shull, J. Michael; Danforth, Charles W.; Tilton, Evan M. E-mail: michael.shull@colorado.edu E-mail: evan.tilton@colorado.edu

    2014-10-10

    The ionizing fluxes from quasars and other active galactic nuclei (AGNs) are critical for interpreting their emission-line spectra and for photoionizing and heating the intergalactic medium. Using far-ultraviolet (FUV) spectra from the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST), we directly measure the rest-frame ionizing continua and emission lines for 159 AGNs at redshifts 0.001 < z {sub AGN} < 1.476 and construct a composite spectrum from 475 to 1875 Å. We identify the underlying AGN continuum and strong extreme ultraviolet (EUV) emission lines from ions of oxygen, neon, and nitrogen after masking out absorption lines from the H I Lyα forest, 7 Lyman-limit systems (N{sub H} {sub I}≥10{sup 17.2} cm{sup –2}) and 214 partial Lyman-limit systems (14.5composite rest-frame continuum shows a gradual break at λ{sub br} ≈ 1000 Å, with mean spectral index α{sub ν} = –0.83 ± 0.09 in the FUV (1200-2000 Å) steepening to α{sub ν} = –1.41 ± 0.15 in the EUV (500-1000 Å). We discuss the implications of the UV flux turnovers and lack of continuum edges for the structure of accretion disks, AGN mass inflow rates, and luminosities relative to Eddington values.

  9. A Composite View of Lower Stratospheric Ozone Developed Using a Chemistry Transport Model and Observations from Airborne Lidar and Satellite

    NASA Technical Reports Server (NTRS)

    Douglass, A. R.; Schoeberl, M. R.; Browell, E. V.

    1999-01-01

    An ozone simulation from the Goddard three-dimensional chemistry and transport model for the 1995-96 northern hemisphere winter is compared with ozone observations from airborne Differential Absorption Lidar (DIAL), from the Polar Ozone and Aerosol Measurement (POAM), from the Microwave Limb Sounder (MLS), and from the Halogen Occultation Experiment (HALOE). The 3D model uses winds from the Goddard Data Assimilation System. The 3D model reproduces the latitude dependence of the horizontal and vertical ozone gradients of the subtropical DIAL observations. Comparisons with subtropical satellite observations, which lack the spatial resolution of DIAL but provide near continuous coverage throughout the subtropics, show that the model also reproduces longitude and temporal dependence in the tropical-midlatitude boundary. At polar latitudes, observations from DIAL flights on December 9 and January 30, and POAM and MLS between late December and late January are compared with the 3D model. Data from the three platforms consistently show that the observed ozone has a negative trend relative to the modeled ozone, and that the trend is uniform in time between early and mid winter, with no obvious dependence on proximity to the vortex edge.

  10. Observational evidence for composite grains in an AGB outflow. MgS in the extreme carbon star LL Pegasi

    NASA Astrophysics Data System (ADS)

    Lombaert, R.; de Vries, B. L.; de Koter, A.; Decin, L.; Min, M.; Smolders, K.; Mutschke, H.; Waters, L. B. F. M.

    2012-08-01

    The broad 30 μm feature in carbon stars is commonly attributed to MgS dust particles. However, reproducing the 30 μm feature with homogeneous MgS grains would require much more sulfur relative to the solar abundance. Direct gas-phase condensation of MgS occurs at a low efficiency. Precipitation of MgS on SiC precursor grains provides a more efficient formation mechanism, such that the assumption of homogeneous MgS grains may not be correct. Using a Monte Carlo-based radiative transfer code, we aim to model the 30 μm feature of the extreme carbon star LL Peg with MgS dust particles. We find that for LL Peg this modeling is insensitive to the unknown MgS optical properties at λ < 10 μm. When MgS is allowed to be in thermal contact with amorphous carbon and SiC, the amount of MgS required to reproduce the strength of 30 μm feature agrees with the solar abundance of sulfur, thereby resolving the reported MgS mass problem. We conclude that MgS is a valid candidate to be the carrier of the 30 μm feature when it is part of a composite grain population that has optical properties representative of an ensemble of particle shapes.

  11. Non-Newtonian behavior observed via dynamic rheology for various particle types in energetic materials and simulant composites

    NASA Astrophysics Data System (ADS)

    Choi, Jong Han; Lee, Sangmook; Lee, Jae Wook

    2017-02-01

    The rheological properties of polymer composites highly filled with different filler materials were examined using a stress-controlled rheometer with a parallel-plate configuration, for particle characterization of the filler materials in plastic (polymer) bonded explosive (PBX). Ethylene vinyl acetate (EVA) with dioctyl adipate (DOA) was used as the matrix phase, which was shown to exhibit Newtonian-like behavior. The dispersed phase consisted of one of two energetic materials, i.e., explosive cyclotrimethylene trinitramine (RDX) or cyclotetramethylene tetranitramine (HMX), or a simulant (Dechlorane) in a bimodal size distribution. Before the test, preshearing was conducted to identify the initial condition of each sample. All examined filled polymer specimens exhibited yield stress and shear-thinning behavior over the investigated frequency range. The complex viscosity dependence on the dynamic oscillation frequency was also fitted using an appropriate rheological model, suggesting the model parameters. Furthermore, the temperature dependency of the different filler particle types was determined for different filler volume fractions. These comparative studies revealed the influence of the particle characteristics on the rheological properties of the filled polymer.

  12. Exploring Mercury's Surface-Bound Exosphere with the Mercury Atmospheric and Surface Composition Spectrometer: AN Overview of Observations during the First Messenger Flyby

    NASA Astrophysics Data System (ADS)

    McClintock, W. E.; Bradley, E. T.; Izenberg, N. R.; Killen, R. M.; Kochte, M. C.; Lankton, M. R.; Mouawad, N.; Sprague, A. L.; Vervack, R. J.

    2008-12-01

    Mercury's surface-bound exosphere is the interface between the planet's surface and the external stimuli that interact with it. Its composition and structure are controlled by surface, magnetosphere, and solar-wind processes. Prior to the MESSENGER mission the exosphere was known to contain H, He, and O from Mariner 10 observations, as well as Na, K, and Ca that were discovered during ground-based observations. Na has been extensively studied since its discovery in 1985, including observations of a neutral Na tail first reported in 2002. Undetected species, including Mg, Fe, Al, and S, are also expected to exist in the exosphere. MESSENGER's initial flyby of Mercury, which occurred on January 14, 2008, offered the first opportunity to measure the planet's neutral tail from space. As the spacecraft approached the planet from the nightside, the UltraViolet and Visible Spectrometer (UVVS) channel of the Mercury Atmospheric and Surface Composition Spectrometer (MASCS) scanned the tail beginning at altitudes of 24,500 km behind Mercury's nightside surface and covering a region of space approximately three planet diameters tall and centered on the Sun-Mercury line. The UVVS measured emissions from Na during the entire observation. It also observed neutral hydrogen beginning approximately 5,000 km above the nightside surface. The spatial distributions of both species were seen to be asymmetric, with enhanced densities occurring in the northern hemisphere. UVVS observations of Ca, which were made as the spacecraft traversed the nightside exosphere, exhibited enhanced emission toward the dawn terminator, with north-south behavior similar to that of Na and H. These observations suggest that the relatively high-energy source processes that give rise to species observed in the tail were localized near the northern and morning hemispheres during the flyby. This inference is supported by magnetic field observations made with the MESSENGER Magnetometer, which observed a strong

  13. Skylab experiments. Volume 5: Astronomy and space physics. [Skylab observations of galactic radiation, solar energy, and interplanetary composition for high school level education

    NASA Technical Reports Server (NTRS)

    1973-01-01

    The astronomy and space physics investigations conducted in the Skylab program include over 20 experiments in four categories to explore space phenomena that cannot be observed from earth. The categories of space research are as follows: (1) phenomena within the solar system, such as the effect of solar energy on Earth's atmosphere, the composition of interplanetary space, the possibility of an inner planet, and the X-ray radiation from Jupiter, (2) analysis of energetic particles such as cosmic rays and neutrons in the near-earth space, (3) stellar and galactic astronomy, and (4) self-induced environment surrounding the Skylab spacecraft.

  14. Multiwavelength Observations of the Powerful Gamma-ray Quasar PKS 1510-089: Clues on the Jet Composition

    SciTech Connect

    Kataoka, J.; Madejski, G.; Sikora, M.; Roming, P.; Chester, M.M.; Grupe, D.; Tsubuku, Y.; Sato, R.; Kawai, N.; Tosti, G.; Impiombato, D.; Kovalev, Y.Y.; Kovalev, Y.A.; Edwards, Philip G.; Wagner, S.J.; Moderski, R.; Stawarz, L.; Takahashi, T.; Watanabe, S.

    2007-09-28

    We present the results from a multiwavelength campaign conducted in August 2006 of the powerful {gamma}-ray quasar PKS 1510--089 (z = 0.361). This campaign commenced with a deep Suzaku observation lasting three days for a total exposure time of 120 ks, and continued with Swift monitoring over 18 days. Besides Swift observations, which sampled the optical/UV flux in all 6 UVOT filters as well as the X-ray spectrum in the 0.3--10 keV energy range, the campaign included ground-based optical and radio data, and yielded a quasi-simultaneous broad-band spectral energy distribution from 109 Hz to 1019 Hz. Thanks to its low instrumental background, the Suzaku observation provided a high S/N X-ray spectrum, which is well represented by an extremely hard power-law with photon index {Gamma}{approx_equal}1.2, augmented by a soft component apparent below 1 keV, which is well described by a black-body model with temperature kT {approx_equal}0.2 keV. Monitoring by Suzaku revealed temporal variability which is different between the low and high energy bands, again suggesting the presence of a second, variable component in addition to the primary power-law emission. We model the broadband spectrum of PKS 1510--089 assuming that the high energy spectral component results from Comptonization of infrared radiation produced by hot dust located in the surrounding molecular torus. In the adopted internal shock scenario, the derived model parameters imply that the power of the jet is dominated by protons but with a number of electrons/positrons exceeding a number of protons by a factor {approx} 10. We also find that inhomogeneities responsible for the shock formation, prior to the collision may produce bulk-Compton radiation which can explain the observed soft X-ray excess and possible excess at {approx} 18 keV. We note, however, that the bulk-Compton interpretation is not unique, and the observed soft excess could arise as well via some other processes discussed briefly in the text.

  15. Film Cooled Recession of SiC/SiC Ceramic Matrix Composites: Test Development, CFD Modeling and Experimental Observations

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Sakowski, Barbara A.; Fisher, Caleb

    2014-01-01

    SiCSiC ceramic matrix composites (CMCs) systems will play a crucial role in next generation turbine engines for hot-section component applications because of their ability to significantly increase engine operating temperatures, reduce engine weight and cooling requirements. However, the environmental stability of Si-based ceramics in high pressure, high velocity turbine engine combustion environment is of major concern. The water vapor containing combustion gas leads to accelerated oxidation and corrosion of the SiC based ceramics due to the water vapor reactions with silica (SiO2) scales forming non-protective volatile hydroxide species, resulting in recession of the ceramic components. Although environmental barrier coatings are being developed to help protect the CMC components, there is a need to better understand the fundamental recession behavior of in more realistic cooled engine component environments.In this paper, we describe a comprehensive film cooled high pressure burner rig based testing approach, by using standardized film cooled SiCSiC disc test specimen configurations. The SiCSiC specimens were designed for implementing the burner rig testing in turbine engine relevant combustion environments, obtaining generic film cooled recession rate data under the combustion water vapor conditions, and helping developing the Computational Fluid Dynamics (CFD) film cooled models and performing model validation. Factors affecting the film cooled recession such as temperature, water vapor concentration, combustion gas velocity, and pressure are particularly investigated and modeled, and compared with impingement cooling only recession data in similar combustion flow environments. The experimental and modeling work will help predict the SiCSiC CMC recession behavior, and developing durable CMC systems in complex turbine engine operating conditions.

  16. Temporal and vertical distribution of acidity and ionic composition in clouds - Comparison between modeling results and observations

    NASA Technical Reports Server (NTRS)

    Defelice, T. P.; Saxena, V. K.

    1990-01-01

    Cyclic temporal variations of pH and ionic concentration in sampled clouds which traversed the Mt. Mitchell State Park (North Carolina) site during the summers of 1986, 1987, and 1988 are reported. These clouds typically had a measured pH minimum during their initial and final stages. The cause of this basic cylic pattern is attributed to sampling at different vertical levels of the cloud. This is substantiated by visual observations made while sampling. The results also suggest that the measured pH patterns do not always exhibit minima during the formative and dissipative stages of the cloud, apparently in response to the underlying dynamical processes. The relationship between temporal pH measurements made at a stationary site to vertical cloud levels provides insights into the physical processes (e.g., nucleation scavenging near cloud base, dry air entrainment near cloud top) influencing the observed cloud-water chemistry on a real-time basis and would improve cloud chemistry models.

  17. Nonadiabatic, momentum-dependent, and energy-dependent corrections in the effective-potential description for low-energy scattering of spinless systems - Their relations and validity

    NASA Technical Reports Server (NTRS)

    Au, C. K.

    1988-01-01

    In the effective-potential description for low-energy scattering involving a spinless complex (a body with internal structure), the nonadiabatic corrections are sometimes disguised in momentum-dependent terms. These are distinct from energy-dependent corrections. A general procedure is given here by which all the momentum-dependent corrections can be converted into nonadiabatic corrections in truly local form. Circumstances under which an expansion of the effective potential, in terms of the adiabatic term plus nonadiabatic and energy-dependent corrections is allowed and forbidden, are discussed. An example for the latter is in the case of near degeneracy in the spectrum of the complex or in the extrapolation of the effective potential to short-distance behavior. This indicates that certain claims of 'saturation effect' at short distances in low-energy electron-atom scattering are invalid.

  18. Composition of gaseous organic carbon during ECOCEM in Beirut, Lebanon: new observational constraints for VOC anthropogenic emission evaluation in the Middle East

    NASA Astrophysics Data System (ADS)

    Salameh, Thérèse; Borbon, Agnès; Afif, Charbel; Sauvage, Stéphane; Leonardis, Thierry; Gaimoz, Cécile; Locoge, Nadine

    2017-01-01

    The relative importance of eastern Mediterranean emissions is suspected to be largely underestimated compared to other regions worldwide. Here we use detailed speciated measurements of volatile organic compounds (VOCs) to evaluate the spatial heterogeneity of VOC urban emission composition and the consistency of regional and global emission inventories downscaled to Lebanon (European Monitoring and Evaluation Programme, EMEP; Atmospheric Chemistry and Climate Model Intercomparison Project, ACCMIP; and MACCity, Monitoring Atmospheric Composition and Climate and megaCITY Zoom for the Environment). The assessment was conducted through the comparison of the emission ratios (ERs) extracted from the emission inventories to the ones obtained from the hourly observations collected at a suburban site in Beirut, Lebanon, during summer and winter ECOCEM (Emissions and Chemistry of Organic Carbon in the Eastern Mediterranean) campaigns. The observed ERs were calculated using two independent methods. ER values from both methods agree very well and are comparable to the ones of the road transport sector from near-field measurements for more than 80 % of the species. There is no significant seasonality in ER for more than 90 % of the species, unlike the seasonality usually observed in other cities worldwide. Regardless of the season, ERs agree within a factor of 2 between Beirut and other representative cities worldwide, except for the unburned fuel fraction and ethane. ERs of aromatics (except benzene) are higher in Beirut compared to northern post-industrialized countries and even the Middle Eastern city Mecca. The comparison of the observed ER to the ones extracted from the ACCMIP and MACCity global emission inventories suggests that the overall speciation of anthropogenic sources for major hydrocarbons that act as ozone and secondary organic aerosol (SOA) precursors in ACCMIP is better represented than other species. The comparison of the specific road transport ERs, relative

  19. The summer 2012 Greenland heat wave: In situ and remote sensing observations of water vapor isotopic composition during an atmospheric river event

    NASA Astrophysics Data System (ADS)

    Bonne, Jean-Louis; Steen-Larsen, Hans Christian; Risi, Camille; Werner, Martin; Sodemann, Harald; Lacour, Jean-Lionel; Fettweis, Xavier; Cesana, Grégory; Delmotte, Marc; Cattani, Olivier; Vallelonga, Paul; Kjær, Helle Astrid; Clerbaux, Cathy; Sveinbjörnsdóttir, Árny Erla; Masson-Delmotte, Valérie

    2015-04-01

    During 7-12 July 2012, extreme moist and warm conditions occurred over Greenland, leading to widespread surface melt. To investigate the physical processes during the atmospheric moisture transport of this event, we study the water vapor isotopic composition using surface in situ observations in Bermuda Island, South Greenland coast (Ivittuut), and northwest Greenland ice sheet (NEEM), as well as remote sensing observations (Infrared Atmospheric Sounding Interferometer (IASI) instrument on board MetOp-A), depicting propagation of similar surface and midtropospheric humidity and δD signals. Simulations using Lagrangian moisture source diagnostic and water tagging in a regional model showed that Greenland was affected by an atmospheric river transporting moisture from the western subtropical North Atlantic Ocean, which is coherent with observations of snow pit impurities deposited at NEEM. At Ivittuut, surface air temperature, humidity, and δD increases are observed. At NEEM, similar temperature increase is associated with a large and long-lasting ˜100‰δD enrichment and ˜15‰ deuterium excess decrease, thereby reaching Ivittuut level. We assess the simulation of this event in two isotope-enabled atmospheric general circulation models (LMDz-iso and ECHAM5-wiso). LMDz-iso correctly captures the timing of propagation for this event identified in IASI data but depict too gradual variations when compared to surface data. Both models reproduce the surface meteorological and isotopic values during the event but underestimate the background deuterium excess at NEEM. Cloud liquid water content parametrization in LMDz-iso poorly impacts the vapor isotopic composition. Our data demonstrate that during this atmospheric river event the deuterium excess signal is conserved from the moisture source to northwest Greenland.

  20. Energy dependence of K π , p π , and K p fluctuations in Au + Au collisions from √{sN N}=7.7 to 200 GeV

    NASA Astrophysics Data System (ADS)

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Alford, J.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Averichev, G. S.; Banerjee, A.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Bouchet, J.; Brandin, A. V.; Bunzarov, I.; Burton, T. P.; Butterworth, J.; Caines, H.; S'anchez, M. Calder'on de la Barca; campbell, J. M.; Cebra, D.; Cervantes, M. C.; Chakaberia, I.; Chaloupka, P.; Chang, Z.; Chattopadhyay, S.; Chen, X.; Chen, J. H.; Cheng, J.; Cherney, M.; Christie, W.; Codrington, M. J. M.; Contin, G.; Crawford, H. J.; Das, S.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; di Ruzza, B.; Didenko, L.; Dilks, C.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Engelage, J.; Eppley, G.; Esha, R.; Evdokimov, O.; Eyser, O.; Fatemi, R.; Fazio, S.; Federic, P.; Fedorisin, J.; Feng, Filip, P.; Fisyak, Y.; Flores, C. E.; Fulek, L.; Gagliardi, C. A.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Greiner, L.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, A.; Gupta, S.; Guryn, W.; Hamad, A.; Hamed, A.; Haque, R.; Harris, J. W.; He, L.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Hofman, D. J.; Horvat, S.; Huang, H. Z.; Huang, B.; 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.; Khan, Z. H.; Kikola, D. P.; Kisel, I.; Kisiel, A.; Klein, S. R.; Koetke, D. D.; Kollegger, T.; Kosarzewski, L. K.; 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.; Li, W.; Li, Z. M.; Li, C.; Li, Y.; Li, X.; Li, X.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, X.; Ma, L.; Ma, R.; Ma, G. L.; Ma, Y. G.; Magdy, N.; Majka, R.; Manion, A.; Margetis, S.; Markert, C.; Masui, H.; Matis, H. S.; McDonald, D.; Meehan, K.; Minaev, N. G.; Mioduszewski, S.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nigmatkulov, G.; Nogach, L. V.; Noh, S. Y.; Novak, J.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Okorokov, V.; Olvitt, D. L.; Page, B. S.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlak, T.; Pawlik, B.; Pei, H.; Perkins, C.; Peterson, A.; Pile, P.; Planinic, M.; Pluta, J.; Poljak, N.; Poniatowska, K.; Porter, J.; Poskanzer, A. M.; Pruthi, N. K.; Putschke, J.; Qiu, H.; Quintero, A.; Ramachandran, S.; Raniwala, S.; Raniwala, R.; Ray, R. L.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Roy, A.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandacz, A.; Sandweiss, J.; 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, M. K.; Sharma, B.; Shen, W. Q.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Sikora, R.; Simko, M.; Skoby, M. J.; Smirnov, D.; Smirnov, N.; Solanki, D.; Song, L.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Sumbera, M.; Summa, B. J.; Sun, Z.; Sun, Y.; Sun, X. M.; Sun, X.; Surrow, B.; Svirida, D. N.; Szelezniak, M. A.; Takahashi, J.; Tang, A. H.; Tang, Z.; Tarnowsky, T.; Tawfik, A. N.; Thomas, J. H.; Tian, J.; Timmins, A. R.; Tlusty, D.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Tripathy, S. K.; Trzeciak, B. A.; Tsai, O. D.; Ullrich, T.; Underwood, D. G.; Upsal, I.; Van Buren, G.; van Nieuwenhuizen, G.; Vandenbroucke, M.; Varma, R.; Vasiliev, A. N.; Vertesi, R.; Videbæk, F.; Viyogi, Y. P.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wang, Y.; Wang, F.; Wang, J. S.; Wang, H.; Wang, G.; Wang, Y.; Webb, J. C.; Webb, G.; Wen, L.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y. F.; Xiao, Z.; Xie, W.; Xin, K.; Xu, N.; Xu, H.; Xu, Y. F.; Xu, Q. H.; Xu, Z.; Yang, Y.; Yang, S.; Yang, C.; Yang, Y.; Yang, Q.; Ye, Z.; Yepes, P.; Yi, L.; Yip, K.; Yoo, I.-K.; Yu, N.; Zbroszczyk, H.; Zha, W.; Zhang, J.; Zhang, Y.; Zhang, S.; Zhang, X. P.; Zhang, J. B.; Zhang, J. L.; Zhang, Z.; Zhao, F.; Zhao, J.; Zhong, C.; Zhu, X.; Zoulkarneeva, Y.; Zyzak, M.; STAR Collaboration

    2015-08-01

    A search for the quantum chromodynamics (QCD) critical point was performed by the STAR experiment at the BNL Relativistic Heavy Ion Collider, using dynamical fluctuations of unlike particle pairs. Heavy ion collisions were studied over a large range of collision energies with homogeneous acceptance and excellent particle identification, covering a significant range in the QCD phase diagram where a critical point may be located. Dynamical K π , p π , and K p fluctuations as measured by the STAR experiment in central 0-5% Au + Au collisions from center-of-mass collision energies √{sN N}=7.7 to 200 GeV are presented. The observable νdyn was used to quantify the magnitude of the dynamical fluctuations in event-by-event measurements of the K π , p π , and K p pairs. The energy dependences of these fluctuations from central 0-5% Au + Au collisions all demonstrate a smooth evolution with collision energy.

  1. Energy dependence of Kπ, pπ and Kp fluctuations in Au+Au collisions from √sNN=7.7 to 200 GeV

    SciTech Connect

    Adamczyk, L.

    2015-08-07

    A search for the quantum chromodynamics (QCD) critical point was performed by the STAR experiment at the Relativistic Heavy Ion Collider, using dynamical fluctuations of unlike particle pairs. Heavy ion collisions were studied over a large range of collision energies with homogeneous acceptance and excellent particle identification, covering a significant range in the QCD phase diagram where a critical point may be located. Dynamical Kπ, pπ, and Kp fluctuations as measured by the STAR experiment in central 0–5% Au+Au collisions from center-of-mass collision energies √sNN=7.7 to 200 GeV are presented. The observable νdyn was used to quantify the magnitude of the dynamical fluctuations in event-by-event measurements of the Kπ, pπ, and Kp pairs. The energy dependences of these fluctuations from central 0–5% Au+Au collisions all demonstrate a smooth evolution with collision energy.

  2. Carbon and hydrogen isotopic compositions of stratospheric methane: 1. High-precision observations from the NASA ER-2 aircraft

    NASA Astrophysics Data System (ADS)

    Rice, A. L.; Tyler, S. C.; McCarthy, M. C.; Boering, K. A.; Atlas, E.

    2003-08-01

    Measurements of δ13C and δD of atmospheric CH4 from whole air samples collected in the upper troposphere and lower stratosphere aboard the NASA ER-2 aircraft during the SOLVE (2000), POLARIS (1997), and STRAT (1996) campaigns are reported. Samples cover latitudes from 1°S to 89°N and altitudes from 11 to 21 km, providing CH4 mixing ratios that range from 1744 to 716 ppbv. Measurements of isotope ratios were made by continuous-flow gas chromatography isotope ratio mass spectrometry which provides high-precision analyses on 60 ml aliquots of air. These measurements comprise the first upper atmosphere isotopic CH4 data set to date using this technique and the most extensive with respect to latitude and season in any case. Values of δ13C-CH4 on the V-PDB scale range from -47.28‰ near the tropical tropopause to -34.05‰ in the high northern latitude stratosphere. Values of δD on the V-SMOW scale range from -90.9‰ to +26.4‰. Correlations of isotope ratios with CH4 mixing ratios show enrichment in the heavy isotopes as CH4 mixing ratios decrease due to kinetic isotope effects associated with oxidation by reaction with OH, Cl, and O(1D). Empirical fractionation factors are found to be highly dependent on the range of CH4 mixing ratio considered, increasing with decreasing mixing ratio. Systematic nonlinearity in a Rayleigh fractionation model suggests a range of stratospheric fractionation factors, αCstrat = 1.0108 ± 0.0004 to 1.0204 ± 0.0004 (2σ) and αHstrat = 1.115 ± 0.008 to 1.198 ± 0.008 (2σ), from high to low CH4 mixing ratio, respectively. The variation in α over the range in mixing ratios reflect changes in partitioning between CH4 sink reactions in different regions of the stratosphere. In Part 1, these new high-precision observations are discussed and compared with other stratospheric and tropospheric isotope measurements. In Part 2 [, 2003] the observations are compared with 2-D model results, and implications for the kinetic isotope effects

  3. An ambispective observational study in the safety and efficacy of posterior colporrhaphy with composite Vicryl-Prolene mesh.

    PubMed

    Lim, Y N; Rane, Ajay; Muller, R

    2005-01-01

    There is increasing evidence to show that the use of surgical meshes reduces recurrence rates of hernia repair and anterior vaginal wall prolapse. The aim of this study was to determine the safety and efficacy of posterior colporrhaphy with mesh in patients with posterior vaginal prolapse. An ambispective observational study involving 90 patients was conducted with retrospective chart review and prospective subjective and objective assessments at the end of a 1-year study period. Apart from 2 of 90 (2.2%) minor hematoma incidents, there was no other major perioperative morbidity. Prevalence of common prolapse complaints of vaginal lump sensation, constipation, defecation difficulty and dyspareunia all improved significantly postoperatively (p<0.001). Surgical correction was achieved in 27 of 31 (83.9%) at 6 months and beyond. There was no mesh infection but minor vaginal mesh protrusion was found in 7 of 90 (7.8%) patients at 6-12 weeks and 4 of 31 (12.9%) patients at 6 months and beyond. All these were treated easily with trimming without the need of mesh removal. We conclude that posterior colporrhaphy with mesh is effective in treating posterior vaginal prolapse in short term.

  4. QUANTIFYING THE ANISOTROPY AND SOLAR CYCLE DEPENDENCE OF '1/f' SOLAR WIND FLUCTUATIONS OBSERVED BY ADVANCED COMPOSITION EXPLORER

    SciTech Connect

    Nicol, R. M.; Chapman, S. C.; Dendy, R. O.

    2009-10-01

    The power spectrum of the evolving solar wind shows evidence of a spectral break between an inertial range (IR) of turbulent fluctuations at higher frequencies and a '1/f' like region at lower frequencies. In the ecliptic plane at approx1 AU, this break occurs approximately at timescales of a few hours and is observed in the power spectra of components of velocity and magnetic field. The '1/f' energy range is of more direct coronal origin than the IR, and carries signatures of the complex magnetic field structure of the solar corona, and of footpoint stirring in the solar photosphere. To quantify the scaling properties we use generic statistical methods such as generalized structure functions and probability density functions (PDFs), focusing on solar cycle dependence and on anisotropy with respect to the background magnetic field. We present structure function analysis of magnetic and velocity field fluctuations, using a novel technique to decompose the fluctuations into directions parallel and perpendicular to the mean local background magnetic field. Whilst the magnetic field is close to '1/f', we show that the velocity field is '1/f {sup {alpha}}' with {alpha} {ne} 1. For the velocity, the value of {alpha} varies between parallel and perpendicular fluctuations and with the solar cycle. There is also variation in {alpha} with solar wind speed. We have examined the PDFs in the fast, quiet solar wind and intriguingly, whilst parallel and perpendicular are distinct, both the B field and velocity show the same PDF of their perpendicular fluctuations, which is close to {gamma} or inverse Gumbel. These results point to distinct physical processes in the corona and to their mapping out into the solar wind. The scaling exponents obtained constrain the models for these processes.

  5. Hygroscopicity and chemical composition of Antarctic sub-micrometre aerosol particles and observations of new particle formation

    NASA Astrophysics Data System (ADS)

    Asmi, E.; Frey, A.; Virkkula, A.; Ehn, M.; Manninen, H. E.; Timonen, H.; Tolonen-Kivimäki, O.; Aurela, M.; Hillamo, R.; Kulmala, M.

    2009-12-01

    The Antarctic near-coastal sub-micrometre aerosol particle features in summer were characterised based on measured data on aerosol hygroscopicity, size distributions, volatility and chemical ion and organic carbon mass concentrations. Hysplit model was used to calculate the history of the air masses to predict the particle origin. Additional measurements of meteorological parameters were utilised. The hygroscopic properties of particles mostly resembled those of marine aerosols. The measurements took place at 130 km from the Southern Ocean, which was the most significant factor affecting the particle properties. This is explained by the lack of additional sources on the continent of Antarctica. The Southern Ocean was thus a likely source of the particles and nucleating and condensing vapours. The particles were very hygroscopic (HGF 1.75 at 90 nm) and very volatile. Most of the sub-100 nm particle volume volatilised below 100 °C. Based on chemical data, particle hygroscopic and volatile properties were explained by a large fraction of non-neutralised sulphuric acid together with organic material. The hygroscopic growth factors assessed from chemical data were similar to measured. Hygroscopicity was higher in dry continental air masses compared with the moist marine air masses. This was explained by the aging of the marine organic species and lower methanesulphonic acid volume fraction together with the changes in the inorganic aerosol chemistry as the aerosol had travelled long time over the continental Antarctica. Special focus was directed in detailed examination of the observed new particle formation events. Indications of the preference of negative over positive ions in nucleation could be detected. However, in a detailed case study, the neutral particles dominated the particle formation process. Freshly nucleated particles had the smallest hygroscopic growth factors, which increased subsequent to particle aging.

  6. Hygroscopicity and chemical composition of Antarctic sub-micrometre aerosol particles and observations of new particle formation

    NASA Astrophysics Data System (ADS)

    Asmi, E.; Frey, A.; Virkkula, A.; Ehn, M.; Manninen, H. E.; Timonen, H.; Tolonen-Kivimäki, O.; Aurela, M.; Hillamo, R.; Kulmala, M.

    2010-05-01

    The Antarctic near-coastal sub-micrometre aerosol particle features in summer were characterised based on measured data on aerosol hygroscopicity, size distributions, volatility and chemical ion and organic carbon mass concentrations. Hysplit model was used to calculate the history of the air masses to predict the particle origin. Additional measurements of meteorological parameters were utilised. The hygroscopic properties of particles mostly resembled those of marine aerosols. The measurements took place at 130 km from the Southern Ocean, which was the most significant factor affecting the particle properties. This is explained by the lack of additional sources on the continent of Antarctica. The Southern Ocean was thus a likely source of the particles and nucleating and condensing vapours. The particles were very hygroscopic (HGF 1.75 at 90 nm) and very volatile. Most of the sub-100 nm particle volume volatilised below 100 °C. Based on chemical data, particle hygroscopic and volatile properties were explained by a large fraction of non-neutralised sulphuric acid together with organic material. The hygroscopic growth factors assessed from chemical data were similar to measured. Hygroscopicity was higher in dry continental air masses compared with the moist marine air masses. This was explained by the aging of the marine organic species and lower methanesulphonic acid volume fraction together with the changes in the inorganic aerosol chemistry as the aerosol had travelled long time over the continental Antarctica. Special focus was directed in detailed examination of the observed new particle formation events. Indications of the preference of negative over positive ions in nucleation could be detected. However, in a detailed case study, the neutral particles dominated the particle formation process. Freshly nucleated particles had the smallest hygroscopic growth factors, which increased subsequent to particle aging.

  7. System Size and Energy Dependence on Strangeness Production in 22 GeV Cu+Cu Collisions at RHIC

    DTIC Science & Technology

    2011-05-10

    relativistic speeds approaching the speed of light before they meet in an extremely high temperature collision. The Solenoidal Tracker at RHIC (STAR...extremely high energy and temperature. This project determines the yield of strange quarks through measurements of K0-short mesons as well as Lambda and Anti...charge. These quarks are never observed alone, but are observable in the form of baryons (3 quarks) or mesons (a quark-anti-quark pair). The

  8. Spatial and Temporal Variability of Trace Gas Columns Derived from WRF/Chem Regional Model Output: Planning for Geostationary Observations of Atmospheric Composition

    NASA Technical Reports Server (NTRS)

    Follette-Cook, M. B.; Pickering, K.; Crawford, J.; Duncan, B.; Loughner, C.; Diskin, G.; Fried, A.; Weinheimer, A.

    2015-01-01

    We quantify both the spatial and temporal variability of column integrated O3, NO2, CO, SO2, and HCHO over the Baltimore / Washington, DC area using output from the Weather Research and Forecasting model with on-line chemistry (WRF/Chem) for the entire month of July 2011, coinciding with the first deployment of the NASA Earth Venture program mission Deriving Information on Surface conditions from Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER-AQ). Using structure function analyses, we find that the model reproduces the spatial variability observed during the campaign reasonably well, especially for O3. The Tropospheric Emissions: Monitoring of Pollution (TEMPO) instrument will be the first NASA mission to make atmospheric composition observations from geostationary orbit and partially fulfills the goals of the Geostationary Coastal and Air Pollution Events (GEO-CAPE) mission. We relate the simulated variability to the precision requirements defined by the science traceability matrices of these space-borne missions. Results for O3 from 0- 2 km altitude indicate that the TEMPO instrument would be able to observe O3 air quality events over the Mid-Atlantic area, even on days when the violations of the air quality standard are not widespread. The results further indicated that horizontal gradients in CO from 0-2 km would be observable over moderate distances (= 20 km). The spatial and temporal results for tropospheric column NO2 indicate that TEMPO would be able to observe not only the large urban plumes at times of peak production, but also the weaker gradients between rush hours. This suggests that the proposed spatial and temporal resolutions for these satellites as well as their prospective precision requirements are sufficient to answer the science questions they are tasked to address.

  9. Late-Time Evolution of Composite Supernova Remnants: Deep Chandra Observations and Hydrodynamical Modeling of a Crushed Pulsar Wind Nebula in SNR G327.1-1.1

    NASA Technical Reports Server (NTRS)

    Temim, Tea; Slane, Patrick; Kolb, Christopher; Blondin, John; Hughes, John P.; Bucciantini, Niccolo

    2015-01-01

    In an effort to better understand the evolution of composite supernova remnants (SNRs) and the eventual fate of relativistic particles injected by their pulsars, we present a multifaceted investigation of the interaction between a pulsar wind nebula (PWN) and its host SNR G327.1-1.1. Our 350 ks Chandra X-ray observations of SNR G327.1-1.1 reveal a highly complex morphology; a cometary structure resembling a bow shock, prong-like features extending into large arcs in the SNR interior, and thermal emission from the SNR shell. Spectral analysis of the non-thermal emission offers clues about the origin of the PWN structures, while enhanced abundances in the PWN region provide evidence for mixing of supernova ejecta with PWN material. The overall morphology and spectral properties of the SNR suggest that the PWN has undergone an asymmetric interaction with the SNR reverse shock(RS) that can occur as a result of a density gradient in the ambient medium and or a moving pulsar that displaces the PWN from the center of the remnant. We present hydrodynamical simulations of G327.1-1.1 that show that its morphology and evolution can be described by a approx. 17,000 yr old composite SNR that expanded into a density gradient with an orientation perpendicular to the pulsar's motion. We also show that the RSPWN interaction scenario can reproduce the broadband spectrum of the PWN from radio to gamma-ray wavelengths. The analysis and modeling presented in this work have important implications for our general understanding of the structure and evolution of composite SNRs.

  10. Continuous Observations of Leaf Transpiration Isotopic Composition in Two Dryland Species Highlight Sensitivity to Changes in Irradiance and Soil Water Content.

    NASA Astrophysics Data System (ADS)

    Wayland, H.; Caylor, K. K.

    2014-12-01

    Advances in optical isotope techniques have enabled near-continuous determination of leaf transpiration isotopic composition (δT), allowing researchers to trace water movement through the soil-plant-atmosphere continuum at fine temporal scales. However, to date very few direct measurements of δT are available. We applied a novel flow-through chamber method developed by Wang et al. (2011) to monitor short-term variability in leaf transpired water isotopic composition of two African savanna trees, Vachiella tortillis and Senegalia mellifera, in response to variable irradiance and soil water content. Single leaves were inserted into a custom cuvette connected to an off-axis integrated cavity output spectroscopy (IA-ICOS) water vapor isotope analyzer and allowed to reach isotopic steady-state. Measurements were taken on alternating species every 10 minutes for two hours during mid-morning when plants were most active. Above-canopy irradiance and soil moisture at rooting depth were recorded daily at 1- and 10-minute intervals, respectively. We found that shading initiated rapid depletion of δ2H and δ18O in both species, though differences were more pronounced in V. tortillis. Similarly, an increase in irradiance caused δ18O enrichment of transpired water by up to 5‰ on the order of minutes. Interestingly, soil water content was positively correlated with δ2H: in drier conditions transpired water was more depleted relative to wetter conditions. Our results suggest that the isotopic composition of leaf water within a canopy may vary considerably depending on leaf location and amount of radiation received. These findings have important implications for models of plant water isotopes and underscore the need for additional direct observations of δT .

  11. LATE-TIME EVOLUTION OF COMPOSITE SUPERNOVA REMNANTS: DEEP CHANDRA OBSERVATIONS AND HYDRODYNAMICAL MODELING OF A CRUSHED PULSAR WIND NEBULA IN SNR G327.1-1.1

    SciTech Connect

    Temim, Tea; Slane, Patrick; Kolb, Christopher; Blondin, John; Hughes, John P.; Bucciantini, Niccoló

    2015-07-20

    In an effort to better understand the evolution of composite supernova remnants (SNRs) and the eventual fate of relativistic particles injected by their pulsars, we present a multifaceted investigation of the interaction between a pulsar wind nebula (PWN) and its host SNR G327.1-1.1. Our 350 Chandra X-ray observations of SNR G327.1-1.1 reveal a highly complex morphology: a cometary structure resembling a bow shock, prong-like features extending into large arcs in the SNR interior, and thermal emission from the SNR shell. Spectral analysis of the non-thermal emission offers clues about the origin of the PWN structures, while enhanced abundances in the PWN region provide evidence for a mixing of supernova ejecta with PWN material. The overall morphology and spectral properties of the SNR suggest that the PWN has undergone an asymmetric interaction with the SNR reverse shock (RS), whichcan occur as a result of a density gradient in the ambient medium and/or a moving pulsar that displaces the PWN from the center of the remnant. We present hydrodynamical simulations of G327.1-1.1 that show that its morphology and evolution can be described by a ∼17,000-year-old composite SNR that expanded into a density gradient with an orientation perpendicular to the pulsar’s motion. We also show that the RS/PWN interaction scenario can reproduce the broadband spectrum of the PWN from radio to γ-ray wavelengths. The analysis and modeling presented in this work have important implications for our general understanding of the structure and evolution of composite SNRs.

  12. Comparison between simulated and observed chemical composition of fine aerosols in Paris (France) during springtime: contribution of regional versus continental emissions

    NASA Astrophysics Data System (ADS)

    Sciare, J.; D'Argouges, O.; Sarda-Estève, R.; Gaimoz, C.; Gros, V.; Zhang, Q. J.; Beekmann, M.; Sanchez, O.

    2010-07-01

    Hourly concentrations of inorganic salts (ions) and carbonaceous material in fine aerosols (aerodynamic diameter, A.D.<2.5 μm) have been determined experimentally from fast measurements performed for a 3-week period in spring 2007 in Paris (France). The sum of these two chemical components (ions and carbonaceous aerosols) has shown to account for most of the fine aerosol mass (PM2.5). This time-resolved dataset allowed investigating the factors controlling the levels of PM2.5 in Paris and showed that polluted periods with PM2.5<15 μg/m3 were characterized by air masses of continental (North-Western Europe) origin and chemical composition made by 75% of ions. By contrast, periods with clean marine air masses have shown the lowest PM2.5 concentrations (typically of about 10 μg/m3); carbonaceous aerosols contributing for most of this mass (typically 75%). In order to better discriminate between regional and continental contributions to the observed chemical composition and concentrations of PM2.5 over Paris, a comparative study was performed between this time-resolved dataset and the outputs of a chemistry transport model (CHIMERE), showing a relatively good capability of the model to reproduce the time-limited intense maxima observed in the field for PM2.5 and ion species. Different model scenarios were then investigated switching off regional and European (North-Western and Central) emissions. Results of these scenarios have clearly shown that most of the ions observed over Paris during polluted periods, were either transported or formed in-situ from gas precursors transported from Northern Europe. By opposite, long-range transport from Europe appeared to poorly contribute to the levels of carbonaceous aerosols observed over Paris. The model failed to properly account for the concentration levels and variability of secondary organic aerosols (SOA) determined experimentally by the EC-tracer method. The abundance of SOA (relatively to organic aerosol, OA) was as

  13. Comparison between simulated and observed chemical composition of fine aerosols in Paris (France) during springtime: contribution of regional versus continental emissions

    NASA Astrophysics Data System (ADS)

    Sciare, J.; D'Argouges, O.; Zhang, Q. J.; Sarda-Estève, R.; Gaimoz, C.; Gros, V.; Beekmann, M.; Sanchez, O.

    2010-12-01

    Hourly concentrations of inorganic salts (ions) and carbonaceous material in fine aerosols (aerodynamic diameter, A.D. <2.5 μm) have been determined experimentally from fast measurements performed for a 3-week period in spring 2007 in Paris (France). The sum of these two chemical components (ions and carbonaceous aerosols) has shown to account for most of the fine aerosol mass (PM2.5). This time-resolved dataset allowed investigating the factors controlling the levels of PM2.5 in Paris and showed that polluted periods with PM2.5 > 15 μg m-3 were characterized by air masses of continental (North-Western Europe) origin and chemical composition made by 75% of ions. By contrast, periods with clean marine air masses have shown the lowest PM2.5 concentrations (typically of about 10 μg m-3); carbonaceous aerosols contributing for most of this mass (typically 75%). In order to better discriminate between local and continental contributions to the observed chemical composition and concentrations of PM2.5 over Paris, a comparative study was performed between this time-resolved dataset and the outputs of a chemistry transport model (CHIMERE), showing a relatively good capability of the model to reproduce the time-limited intense maxima observed in the field for PM2.5 and ion species. Different model scenarios were then investigated switching off local and European (North-Western and Central) emissions. Results of these scenarios have clearly shown that most of the ions observed over Paris during polluted periods, were either transported or formed in-situ from gas precursors transported from Northern Europe. On the opposite, long-range transport from Europe appeared to weakly contribute to the levels of carbonaceous aerosols observed over Paris. The model failed to properly account for the concentration levels and variability of secondary organic aerosols (SOA) determined experimentally by the EC-tracer method. The abundance of SOA (relatively to organic aerosol, OA) was as

  14. ISEE observations of the plasma sheet boundary, plasma sheet, and neutral sheet. I - Electric field, magnetic field, plasma, and ion composition

    NASA Technical Reports Server (NTRS)

    Cattell, C. A.; Mozer, F. S.; Hones, E. W., Jr.; Anderson, R. R.; Sharp, R. D.

    1986-01-01

    The first simultaneous study of dc and ac electric and magnetic fields, E x B velocity, plasma flows, ratio of plasma to magnetic field pressure, total energy density, energetic particles, and ion composition from the ISEE satellites and ground and interplanetary magnetic fields has been made to determine (1) the relationship of the previously observed electric fields at the plasma sheet boundary and at the neutral sheet to plasma parameters, and (2) whether the phenomena occurring during quiet and active times were consistent with the formation of a near-earth neutral line during substorms or with the boundary layer model. Five observations made during the study of two substorms were seen to be in agreement with the neutral-line model. The observations are consistent with the satellite being located at varying distances from the neutral line and diffusion region where reconnection and plasma acceleration were occurring. Although the z component (into or out of the ecliptic plane) of E x B convection was generally toward the neutral sheet, there were examples when it was consistent with the inferred motion of the plasma sheet past the satellite. A synthesis of previous reports on large electric fields at the plasma sheet boundary and variable fields at the neutral sheet including the associated plasma flows is also described.

  15. Effect of Gamma Irradiation on Cement Composites Observed with XRD and SEM Methods in the Range of Radiation Dose 0-1409 MGy

    NASA Astrophysics Data System (ADS)

    Łowińska-Kluge, A.; Piszora, P.

    2008-08-01

    The effect of gamma radiation in the range of 0-1409 MGy on the structure of a new mineral additive to cement based composites was investigated in the perspective of employing them as radioactive waste protection material. According to the authors knowledge, it is the first paper dealing with observations of the cement matrix, both pure and modified, treated with so giant radiation dose. The absorption of gamma radiation modifies the morphology of the additive grains, causes decomposition of cement hydrates and clinker relicts in cement paste containing the additive at twice higher radiation dose than that inducing the decomposition of the reference pure cement paste and the cement paste containing pozzolane additives.

  16. Quantifying global atmospheric sulfate formation pathways utilizing observations and modeling of the oxygen isotopic composition (Δ17O) of sulfate aerosol (Invited)

    NASA Astrophysics Data System (ADS)

    Alexander, B.

    2010-12-01

    Sulfate is a major component of the atmospheric aerosol and drives the formation of new aerosol particles through nucleation. The implications for scattering of solar radiation and for cloud microphysics represent one of the largest uncertainties in current assessments of climate change. The specific formation pathway of secondary sulfate in the atmosphere has implications for climate, as only sulfate formed through gas-phase oxidation can nucleate new particles under favorable conditions, increasing aerosol number density. Sulfate produced in the aqueous phase is present in larger particles and does not lead to nucleation of new particles. The oxygen isotopic composition (Δ17O = δ17O - 0.52 x δ18O) of sulfate aerosol can be used as a means to quantify various sulfate production mechanisms in the atmosphere. Large-scale models of the atmosphere typically include sulfate production in the gas-phase by the hydroxyl radical (OH) and in cloud droplet by hydrogen peroxide (H2O2) and ozone (O3). Additional reaction pathways are considered minor and therefore neglected. While these models typically reproduce observations of sulfate aerosol concentration to within 20%, SO2 concentrations are overestimated by a factor of two or more. Here, I compare observations of the oxygen isotopic composition of sulfate aerosol collected at the surface at various locations around the world to calculated sulfate Δ17O in a global model. This model-measurement comparison is used to assess the global importance of sulfate production on alkaline sea-salt and dust aerosol, metal catalyzed oxidation by O2 in cloud droplets, and oxidation by halogen oxidizes. I will show how these additional sulfur oxidation pathways influence the global sulfur budget, to what degree they resolve the global model’s bias in SO2 concentrations, and how they influence the contribution of atmospheric sulfate produced in the gas-phase.

  17. Testosterone replacement therapy to improve secondary sexual characteristics and body composition without adverse behavioral problems in adult male patients with Prader-Willi syndrome: an observational study.

    PubMed

    Kido, Yasuhiro; Sakazume, Satoru; Abe, Yoshiko; Oto, Yuji; Itabashi, Hisashi; Shiraishi, Masahisa; Yoshino, Atsunori; Tanaka, Yuriko; Obata, Kazuo; Murakami, Nobuyuki; Nagai, Toshiro

    2013-09-01

    Prader-Willi syndrome (PWS), a complex genetic disorder, arises from suppressed expression of paternally inherited imprinted genes on chromosome 15q11-q13. Characteristics include short stature, intellectual disability, behavioral problems, hypogonadism, obesity, and reduced bone and muscle mass. Testosterone replacement (TR) remains controversial due to concerns regarding behavioral problems. To evaluate the effects of TR on secondary sexual characteristics, body composition, and behavior in adult males with PWS, 22 male PWS patients over the age of 16 with behavioral scores of less than grade 4 on the Modified Overt Aggression Scale (MOAS) underwent monthly intramuscular TR (125 mg). Pubertal change, body composition and behavior were evaluated before and after 24 months of therapy. Serum testosterone, LH, and FSH did not change. Increased pubic hair was observed in 16 of 22 patients (72.7%). Percent body fat decreased from 47.55 ± 2.06% to 39.75 ± 1.60% (n = 18) (P = 0.018). Bone mineral density increased from 0.8505 ± 0.0426 g/cm(2) to 0.9035 ± 0.0465 g/cm(2) (n = 18) (P = 0.036), and lean body mass increased from 18093.4 ± 863.0 g to 20312.1 ± 1027.2 g (n = 18) (P = 0.009). The MOAS was unchanged, from 4.5 ± 2.0 at the beginning of the study to 3.0 ± 1.7 at the end of study indicating no increase in aggression. No behavioral problems were observed. Based on this pilot study, TR with 125 mg monthly is a potentially safe and useful intervention for adult males with PWS.

  18. Comparisons of the four Miller Range nakhlites, MIL 03346, 090030, 090032 and 090136: Textural and compositional observations of primary and secondary mineral assemblages

    NASA Astrophysics Data System (ADS)

    Hallis, Lydia J.; Taylor, G. J.

    2011-12-01

    Petrological and geochemical analyses of Miller Range (MIL) 03346 indicate that this meteorite originated from the same augitic cumulate layer(s) as the nakhlite Martian meteorites, but underwent rapid cooling prior to complete crystallization. As with the other nakhlites, MIL 03346 contains a secondary alteration assemblage, in this case consisting of iddingsite-like alteration veins in olivine phenocrysts, Fe-oxide alteration veins associated with the mesostasis, and Ca- and K,Fe-sulfate veins. We compared the textural and mineralogical compositions of MIL 090030, 090032, and 090136 with MIL 03346, focusing on the composition and Raman spectra of the alteration assemblages. These observations indicate that the meteorites are paired, and that the preterrestrial olivine-bound alteration assemblages were produced by weakly acidic brine. Although these alteration assemblages resemble similar assemblages in Nakhla, the absence of siderite and halite in the Miller Range nakhlites indicates that the parental alteration brine was comparatively HCO3- depleted, and less concentrated, than that which altered Nakhla. This indicates that the Miller Range nakhlite alteration brine experienced a separate evolutionary pathway to that which altered Nakhla, and therefore represents a separate branch of the Lafayette-Nakhla evaporation sequence. Thin-sections cut from the internal portions of these meteorites (away from any fusion crust or terrestrially exposed edge), contain little Ca-sulfate (identified as gypsum), and no jarosite, whereas thin-sections with terrestrially exposed edges have much higher sulfate abundances. These observations suggest that at least the majority of sulfate within the Miller Range nakhlites is terrestrially derived.

  19. Energy dependence of the optical potential of weakly and tightly bound nuclei as projectiles on a medium-mass target

    SciTech Connect

    Figueira, J. M.; Arazi, A.; Carnelli, P.; Heimann, D. Martinez; Negri, A. E.; Pacheco, A. J.; Niello, J. O. Fernandez; Capurro, O. A.; Fimiani, L.; Marti, G. V.; Lubian, J.; Monteiro, D. S.; Gomes, P. R. S.

    2010-02-15

    Angular distributions for the elastic scattering of the weakly bound {sup 6,7}Li+{sup 144}Sm systems were measured with high accuracy at bombarding energies from 85% up to 170% of the Coulomb barrier. An optical model analysis was performed, and the relevant parameters of the real and imaginary parts of the optical potential were extracted. The results are compared with those previously published for the tightly bound {sup 12}C+{sup 144}Sm and {sup 16}O+{sup 144}Sm systems. The usual threshold anomaly observed in the behavior of the potential of tightly bound systems was not observed for either weakly bound system. This absence is attributed to the repulsion due to breakup coupling which cancels the attraction arising from couplings with bound channels.

  20. Biomass Burning Influences on the Composition of the Remote South Pacific Troposphere: Analysis Based on Observations from PEM Tropics-A

    NASA Technical Reports Server (NTRS)

    Singh, H. B.; Viezee, W.; Chen, Y.; Bradshaw, J.; Sandholm, S.; Blake, D.; Blake, N.; Heikes, B.; Snow, J.; Talbot, R.; Sachse, G.; Vay, S.

    1999-01-01

    Airborne, in-situ measurements from PEM-Tropics-A (September/October 1996) are analyzed to show the presence of distinct pollution plumes in the middle-tropical troposphere of the remote South Pacific (10-30degS). These elevated plumes cause a relative maximum at about 5-7km attitude in the vertical distribution of primary and secondary species characteristic of fuel combustion and biomass burning (CO, C2H2, C2H6, CH3Cl, PAN, O3). Similar plumes were also observed at mid-latitudes in the middle troposphere during three flights east of New Zealand (40-45degS). In all, pollution plumes with CO larger than 100 ppb were observed 24 times on 7 separate flight days south of the equator. The observed plumes were generally embedded in very dry air. Ten-day back trajectory analysis supports the view that these originated from the biomass burning regions of South Africa (and South America) and were transported to the South Pacific along long-distance subsiding trajectories. The chemical composition of the southern Pacific troposphere analyzed from the PEM-Tropics-A data is compared with data from the tropical regions of the northern Pacific (PEM-West-A) and southern Atlantic (TRACE-A) during the same Sept/Oct time period. Sizable perturbations in the abundance of ozone and its key precursors, resulting from the transport of pollution originating from biomass burning sources, are observed in much of the Southern Hemispheric troposphere.

  1. Vanishing rainbows near orbiting and the energy dependence of rainbow scattering - Relation to properties of the potential. [molecular beam scattering cross sections

    NASA Technical Reports Server (NTRS)

    Greene, E. F.; Hall, R. B.; Mason, E. A.

    1975-01-01

    The energy threshold behavior of elastic rainbow scattering near the transition to orbiting is derived. Analysis of the energy dependence of the rainbow angle shows that the full range from high energies down to orbiting can be fitted with two parameters. Thus, measurements of the rainbow angle can give essentially only two pieces of information about the potential. For potentials of common shapes, such measurements are sensitive to regions of the potential just beyond the minimum and give information about the shape of the potential in this range. However, neither a minimum nor a point of inflection in the potential is necessary for rainbow scattering.

  2. Momentum and energy dependent resolution function of the ARCS neutron chopper spectrometer at high momentum transfer: Comparing simulation and experiment

    NASA Astrophysics Data System (ADS)

    Diallo, S. O.; Lin, J. Y. Y.; Abernathy, D. L.; Azuah, R. T.

    2016-11-01

    Inelastic neutron scattering at high momentum transfers (i.e. Q ≥ 20 A ˚), commonly known as deep inelastic neutron scattering (DINS), provides direct observation of the momentum distribution of light atoms, making it a powerful probe for studying single-particle motions in liquids and solids. The quantitative analysis of DINS data requires an accurate knowledge of the instrument resolution function Ri(Q , E) at each momentum Q and energy transfer E, where the label i indicates whether the resolution was experimentally observed i = obs or simulated i=sim. Here, we describe two independent methods for determining the total resolution function Ri(Q , E) of the ARCS neutron instrument at the Spallation Neutron Source, Oak Ridge National Laboratory. The first method uses experimental data from an archetypical system (liquid 4He) studied with DINS, which are then numerically deconvoluted using its previously determined intrinsic scattering function to yield Robs(Q , E). The second approach uses accurate Monte Carlo simulations of the ARCS spectrometer, which account for all instrument contributions, coupled to a representative scattering kernel to reproduce the experimentally observed response S(Q , E). Using a delta function as scattering kernel, the simulation yields a resolution function Rsim(Q , E) with comparable lineshape and features as Robs(Q , E), but somewhat narrower due to the ideal nature of the model. Using each of these two Ri(Q , E) separately, we extract characteristic parameters of liquid 4He such as the intrinsic linewidth α2 (which sets the atomic kinetic energy < K > ∼α2) in the normal liquid and the Bose-Einstein condensate parameter n0 in the superfluid phase. The extracted α2 values agree well with previous measurements at saturated vapor pressure (SVP) as well as at elevated pressure (24 bars) within experimental precision, independent of which Ri(Q , y) is used to analyze the data. The actual observed n0 values at each Q vary little

  3. Morphological Observations and Fatty Acid Composition of Indoor-Cultivated Cordyceps sinensis at a High-Altitude Laboratory on Sejila Mountain, Tibet

    PubMed Central

    Guo, Lian-Xian; Xu, Xiao-Ming; Liang, Fu-Rui; Yuan, Jian-Ping; Peng, Juan; Wu, Chou-Fei; Wang, Jiang-Hai

    2015-01-01

    Cordyceps sinensis, a caterpillar entomopathogenic fungus-host larva complex, is a rare medicinal herb found in the Qinghai-Tibetan Plateau and its surrounding high-altitude areas. The alternation of generations in the life cycle, whatever the fungus or its host insect, requires special growth conditions. However, it is difficult to simulate the growth conditions of C. sinensis, which hinders its artificial cultivation. In this work, the life cycle from the host larva to C. sinensis was observed in an indoor-cultivation laboratory at 4,200 m a.s.l. on Sejila Mountain, Tibet. Comparative examinations between indoor-cultivated and wild C. sinensis demonstrated that the indoor-cultivated C. sinensis preferred to germinate multiple long, slim stromata at diverse positions on dead larvae, including but not limited to their heads. Their fatty acid composition shows a significant difference in the levels of polyunsaturated fatty acids (PUFAs). In indoor-cultivated C. sinensis, PUFAs constituted 24.59% and 49.43%, respectively, of neutral and polar lipids; meanwhile, in wild C. sinensis, PUFAs represented 34.34% and 61.25% of neutral and polar lipids, respectively. These observations and fatty acid data suggest that environmental factors, particularly temperature, soil pressure and light intensity, strongly affect the growth of C. sinensis. Our new findings may provide important information for improving techniques for the large-scale artificial cultivation of C. sinensis. PMID:25938484

  4. Milk composition of captive vervet monkey (Chlorocebus pygerythrus) and rhesus macaque (Macaca mulatta) with observations on gorilla (Gorilla gorilla gorilla) and white handed gibbon (Hylobates lar).

    PubMed

    Osthoff, G; Hugo, A; de Wit, M; Nguyen, T P M; Seier, J

    2009-04-01

    The nutrient content and fatty acid composition of vervet monkey milk has been determined and is compared with rhesus macaque, and two hominoid apes, the white handed gibbon and gorilla. With 15.7+/-4.1 g protein, 33.1+/-9.4 g fat, and 85.1+/-7.5 g lactose per kg milk, vervet monkey milk does not differ from that of rhesus macaque, and is within the range of other primates. Small amounts (>1 g kg(-1)) of oligosaccharides, glucose, galactose and fucose were noted. In comparison, gorilla milk has a low fat content of 13.8 g kg(-1), but contains high levels of oligosaccharides at 7.0 g kg(-1) milk. The hominoid partner, the white handed gibbon, contains no oligosaccharides and a milk fat content similar to other hominoid species. Differences between vervet monkey and rhesus macaque milks were observed in the electrophoretic pattern of the milk proteins, mainly amongst the kappa- and gamma-caseins, which also differ from that of the hominids. The fatty acid contents of these milks differ from studies where a natural diet of leafy material was available in that a low content of alpha-linolenic acid (18:3n-3) was noted. A phylogenetic effect is observed for the content of 8:0, 10:0 fatty acids between the Cercopithecidae and Hominoidea, and a further phylogenetic effect suggested between the Hylobatidae and Hominidae.

  5. HONO and Inorganic Fine Particle Composition in Typical Monsoon Region with Intensive Anthropogenic Emission: In-situ Observations and Source Identification.

    NASA Astrophysics Data System (ADS)

    Xie, Y.; Nie, W.; Ding, A.; Huang, X.

    2015-12-01

    Yangtze River Delta (YRD) is one of the most typical monsoon area with probably the most largest population intensity in the world. With sharply economic development and the large anthropogenic emissions, fine particle pollution have been one of the major air quality problem and may further have impact on the climate system. Though a lot of control policy (sulfur emission have been decreasing from 2007) have been conducted in the region, studies showed the sulfate in fine particles still take major fraction as the nitrate from nitrogen oxides increased significantly. In this study, the role of inorganic chemical compositions in fine particles was investigated with two years in-situ observation. Sulfate and Nitrate contribute to fine particle mass equally in general, but sulfate contributes more during summer and nitrate played more important role in winter. Using lagrangian dispersion backward modeling and source contribution clustering method, the impact of airmass coming from different source region (industrial, dust, biogenic emissions, etc) on fine particle inorganic compositions were discussed. Furthermore, we found two unique cases showing in-situ implications for sulfate formation by nitrogen dioxide oxidation mechanisms. It was showed that the mixing of anthropogenic pollutants with long-range transported mineral dust and biomass burning plume would enhance the sulfate formation by different chemistry mechanisms. This study focus on the complex aspects of fine particle formation in airmasses from different source regions: . It highlights the effect of NOx in enhancing the atmospheric oxidization capacity and indicates a potentially very important impact of increasing NOx on air pollution formation and regional climate change in East Asia.

  6. An 8-year record of gas geochemistry and isotopic composition of methane during baseline sampling at a groundwater observation well in Alberta (Canada)

    NASA Astrophysics Data System (ADS)

    Humez, P.; Mayer, B.; Nightingale, M.; Ing, J.; Becker, V.; Jones, Don; Lam, Vien

    2016-02-01

    Variability in baseline groundwater methane concentrations and isotopic compositions was assessed while comparing free and dissolved gas sampling approaches for a groundwater monitoring well in Alberta (Canada) over an 8-year period. Methane concentrations in dissolved gas samples ( n = 12) were on average 4,380 ± 2,452 μg/L, yielding a coefficient of variation (CV) >50 %. Methane concentrations in free gas samples ( n = 12) were on average 228,756 ± 62,498 ppm by volume, yielding a CV of 27 %. Quantification of combined sampling, sample handling and analytical uncertainties was assessed via triplicate sampling (CV of 19 % and 12 % for free gas and dissolved gas methane concentrations, respectively). Free and dissolved gas samples yielded comparable methane concentration patterns and there was evidence that sampling operations and pumping rates had a marked influence on the obtained methane concentrations in free gas. δ13CCH4 and δ2HCH4 values of methane were essentially constant (-78.6 ± 1.3 and -300 ± 3 ‰, respectively) throughout the observation period, suggesting that methane was derived from the same biogenic source irrespective of methane concentration variations. The isotopic composition of methane constitutes a robust and highly valuable baseline parameter and increasing δ13CCH4 and δ2HCH4 values during repeat sampling may indicate influx of thermogenic methane. Careful sampling and analytical procedures with identical and repeatable approaches are required in baseline-monitoring programs to generate methane concentration and isotope data for groundwater that can be reliably compared to repeat measurements once potential impact from oil and gas development, for example, may occur.

  7. An experimental study of energy dependence of saturation thickness of multiply scattered gamma rays in binary alloys

    SciTech Connect

    Singh, Gurvinderjit; Singh, Bhajan Sandhu, B. S.

    2015-08-28

    The present measurements are carried out to investigate the multiple scattering of 662 keV gamma photons emerging from targets of binary alloys (brass and soldering material). The scattered photons are detected by 51 mm × 51 mm NaI(Tl) scintillation detector whose response unscrambling converting the observed pulse–height distribution to a true photon energy spectrum, is obtained with the help of 10 × 10 inverse response matrix. The numbers of multiply scattered events, having same energy as in the singly scattered distribution, first increases with target thickness and then saturate. The application of response function of scintillation detector does not result in any change of measured saturation thickness. Monte Carlo calculation supports the present experimental results.

  8. Energy dependence of dissociative J/ψ photoproduction as a signature of gluon saturation at the LHC

    NASA Astrophysics Data System (ADS)

    Cepila, J.; Contreras, J. G.; Tapia Takaki, J. D.

    2017-03-01

    We have developed a model in which the quantum fluctuations of the proton structure are characterised by hot spots, whose number grows with decreasing Bjorken-x. Our model reproduces the F2 (x ,Q2) data from HERA at the relevant scale, as well as the exclusive and dissociative J / ψ photoproduction data from H1 and ALICE. Our model predicts that for Wγp ≈ 500 GeV, the dissociative J / ψ cross section reaches a maximum and then decreases steeply with energy, which is in qualitatively good agreement to a recent observation that the dissociative J / ψ background in the exclusive J / ψ sample measured in photoproduction by ALICE decreases as energy increases. Our prediction provides a clear signature for gluon saturation at LHC energies.

  9. Energy-dependent evolution in IC10 X-1: hard evidence for an extended corona and implications

    SciTech Connect

    Barnard, R.; Steiner, J. F.; Prestwich, A. F.; Stevens, I. R.; Clark, J. S.; Kolb, U. C.

    2014-09-10

    We have analyzed a ∼130 ks XMM-Newton observation of the dynamically confirmed black hole + Wolf-Rayet (BH+WR) X-ray binary (XB) IC10 X-1, covering ∼1 orbital cycle. This system experiences periodic intensity dips every ∼35 hr. We find that energy-independent evolution is rejected at a >5σ level. The spectral and timing evolution of IC10 X-1 are best explained by a compact disk blackbody and an extended Comptonized component, where the thermal component is completely absorbed and the Comptonized component is partially covered during the dip. We consider three possibilities for the absorber: cold material in the outer accretion disk, as is well documented for Galactic neutron star (NS) XBs at high inclination; a stream of stellar wind that is enhanced by traveling through the L1 point; and a spherical wind. We estimated the corona radius (r {sub ADC}) for IC10 X-1 from the dip ingress to be ∼10{sup 6} km, assuming absorption from the outer disk, and found it to be consistent with the relation between r {sub ADC} and 1-30 keV luminosity observed in Galactic NS XBs that spans two orders of magnitude. For the other two scenarios, the corona would be larger. Prior BH mass (M {sub BH}) estimates range over 23-38 M {sub ☉}, depending on the inclination and WR mass. For disk absorption, the inclination, i, is likely to be ∼60-80°, with M {sub BH} ∼ 24-41 M {sub ☉}. Alternatively, the L1-enhanced wind requires i ∼ 80°, suggesting ∼24-33 M {sub ☉}. For a spherical absorber, i ∼ 40°, and M {sub BH} ∼ 50-65 M {sub ☉}.

  10. Energy Dependence of the Ruthenium(II)-Bipyridine Metal-to-Ligand-Charge-Transfer Excited State Radiative Lifetimes: Effects of ππ*(bipyridine) Mixing.

    PubMed

    Thomas, Ryan A; Tsai, Chia Nung; Mazumder, Shivnath; Lu, I Chen; Lord, Richard L; Schlegel, H Bernhard; Chen, Yuan Jang; Endicott, John F

    2015-06-18

    The variations in band shape with excited state energy found for the triplet metal to ligand charge transfer ((3)MLCT) emission spectra of ruthenium-bipyridine (Ru-bpy) chromophores at 77 K have been postulated to arise from excited state/excited state configurational mixing. This issue is more critically examined through the determination of the excited state energy dependence of the radiative rate constants (kRAD) for these emissions. Experimental values for kRAD were determined relative to known literature references for Ru-bpy complexes. When the lowest energy excited states are metal centered, kRAD can be anomalously small and such complexes have been identified using density functional theory (DFT) modeling. When such complexes are removed from the energy correlation, there is a strong (3)MLCT energy-dependent contribution to kRAD in addition to the expected classical energy cubed factor for complexes with excited state energies greater than 10 000 cm(-1). This correlates with the DFT calculations which show significant excited state electronic delocalization between a π(bpy-orbital) and a half-filled dπ*-(Ru(III)-orbital) for Ru-bpy complexes with (3)MLCT excited state energies greater than about 16 000 cm(-1). Overall, this work implicates the "stealing" of emission bandshapes as well as intensity from the higher energy, strongly allowed bpy-centered singlet ππ* excited state.

  11. A general scaling rule for the collision energy dependence of a rotationally inelastic differential cross-section and its application to NO(X) + He.

    PubMed

    Zhang, Xia; Eyles, Chris J; Taatjes, Craig A; Ding, Dajun; Stolte, Steven

    2013-04-21

    The quasi-quantum treatment (QQT) (Gijsbertsen et al., J. Am. Chem. Soc., 2006, 128, 8777) provides a physically compelling framework for the evaluation of rotationally inelastic scattering, including the differential cross sections (DCS). In this work the QQT framework is extended to treat the DCS in the classically forbidden region as well as the classically allowed region. Most importantly, the QQT is applied to the collision energy dependence of the angular distributions of these DCSs. This leads to an analytical formalism that reveals a scaling relationship between the DCS calculated at a particular collision energy and the DCS at other collision energies. This scaling is shown to be exact for QM calculated or experimental DCSs if the magnitude of the (kinematic apse frame) underlying scattering amplitude depends solely on the projection of the incoming momentum vector onto the kinematic apse vector. The QM DCSs of the NO(X)-He collision system were found to obey this scaling law nearly perfectly for energies above 63 meV. The mathematical derivation is accompanied by a mechanistic description of the Feynman paths that contribute to the scattering amplitude in the classically allowed and forbidden regions, and the nature of the momentum transfer during the collision process. This scaling relationship highlights the nature of (and limits to) the information that is obtainable from the collision-energy dependence of the DCS, and allows a description of the relevant angular range of the DCSs that embodies this information.

  12. Beam Energy Dependence of the Third Harmonic of Azimuthal Correlations in Au+Au Collisions at RHIC

    DOE PAGES

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; ...

    2016-03-18

    In this paper, we present results from a harmonic decomposition of two-particle azimuthal correlations measured with the STAR detector in Au + Au collisions for energies ranging from √sNN = 7.7 to 200 GeV. The third harmonic vmore » $$2\\atop{3}$${ 2 } = , where Φ1 - Φ2 is the angular difference in azimuth, is studied as a function of the pseudorapidity difference between particle pairs Δη = η1-η2 . Nonzero v$$2\\atop{3}$${ 2 } is directly related to the previously observed large- Δη narrow- ΔΦ ridge correlations and has been shown in models to be sensitive to the existence of a low viscosity quark gluon plasma phase. For sufficiently central collisions, v$$2\\atop{3}$${ 2 } persist down to an energy of 7.7 GeV, suggesting that quark gluon plasma may be created even in these low energy collisions. In peripheral collisions at these low energies, however, v$$2\\atop{3}$${ 2 } is consistent with zero. Finally, when scaled by the pseudorapidity density of charged-particle multiplicity per participating nucleon pair, v$$2\\atop{3}$${ 2 } for central collisions shows a minimum near √sNN = 20 GeV .« less

  13. Beam Energy Dependence of the Third Harmonic of Azimuthal Correlations in Au+Au Collisions at RHIC.

    PubMed

    Adamczyk, L; Adkins, J K; Agakishiev, G; Aggarwal, M M; Ahammed, Z; Alekseev, I; Aparin, A; Arkhipkin, D; Aschenauer, E C; Attri, A; Averichev, G S; Bai, X; Bairathi, V; Bellwied, R; Bhasin, A; Bhati, A K; Bhattarai, P; Bielcik, J; Bielcikova, J; Bland, L C; Bordyuzhin, I G; Bouchet, J; Brandenburg, J D; Brandin, A V; Bunzarov, I; Butterworth, J; Caines, H; Calderón de la Barca Sánchez, M; Campbell, J M; Cebra, D; Chakaberia, I; Chaloupka, P; Chang, Z; Chatterjee, A; Chattopadhyay, S; Chen, J H; Chen, X; Cheng, J; Cherney, M; Christie, W; Contin, G; Crawford, H J; Das, S; De Silva, L C; Debbe, R R; Dedovich, T G; Deng, J; Derevschikov, A A; di Ruzza, B; Didenko, L; Dilks, C; Dong, X; Drachenberg, J L; Draper, J E; Du, C M; Dunkelberger, L E; Dunlop, J C; Efimov, L G; Engelage, J; Eppley, G; Esha, R; Evdokimov, O; Eyser, O; Fatemi, R; Fazio, S; Federic, P; Fedorisin, J; Feng, Z; Filip, P; Fisyak, Y; Flores, C E; Fulek, L; Gagliardi, C A; Garand, D; Geurts, F; Gibson, A; Girard, M; Greiner, L; Grosnick, D; Gunarathne, D S; Guo, Y; Gupta, S; Gupta, A; Guryn, W; Hamad, A I; Hamed, A; Haque, R; Harris, J W; He, L; Heppelmann, S; Heppelmann, S; Hirsch, A; Hoffmann, G W; Horvat, S; Huang, T; Huang, X; Huang, B; Huang, H Z; Huck, P; Humanic, T J; Igo, G; Jacobs, W W; Jang, H; Jentsch, A; Jia, J; Jiang, K; Judd, E G; Kabana, S; Kalinkin, D; Kang, K; Kauder, K; Ke, H W; Keane, D; Kechechyan, A; Khan, Z H; Kikoła, D P; Kisel, I; Kisiel, A; Kochenda, L; Koetke, D D; Kosarzewski, L K; Kraishan, A F; Kravtsov, P; Krueger, K; Kumar, L; Lamont, M A C; Landgraf, J M; Landry, K D; Lauret, J; Lebedev, A; Lednicky, R; Lee, J H; Li, X; Li, C; Li, X; Li, Y; Li, W; Lin, T; Lisa, M A; Liu, F; Ljubicic, T; Llope, W J; Lomnitz, M; Longacre, R S; Luo, X; Ma, R; Ma, G L; Ma, Y G; Ma, L; Magdy, N; Majka, R; Manion, A; Margetis, S; Markert, C; Matis, H S; McDonald, D; McKinzie, S; Meehan, K; Mei, J C; Minaev, N G; Mioduszewski, S; Mishra, D; Mohanty, B; Mondal, M M; Morozov, D A; Mustafa, M K; Nandi, B K; Nasim, Md; Nayak, T K; Nigmatkulov, G; Niida, T; Nogach, L V; Noh, S Y; Novak, J; Nurushev, S B; Odyniec, G; Ogawa, A; Oh, K; Okorokov, V A; Olvitt, D; Page, B S; Pak, R; Pan, Y X; Pandit, Y; Panebratsev, Y; Pawlik, B; Pei, H; Perkins, C; Pile, P; Pluta, J; Poniatowska, K; Porter, J; Posik, M; Poskanzer, A M; Pruthi, N K; Putschke, J; Qiu, H; Quintero, A; Ramachandran, S; Raniwala, S; Raniwala, R; Ray, R L; Ritter, H G; Roberts, J B; Rogachevskiy, O V; Romero, J L; Ruan, L; Rusnak, J; Rusnakova, O; Sahoo, N R; Sahu, P K; Sakrejda, I; Salur, S; Sandweiss, J; 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, A; Sharma, B; Sharma, M K; Shen, W Q; Shi, Z; Shi, S S; Shou, Q Y; Sichtermann, E P; Sikora, R; Simko, M; Singha, S; Skoby, M J; Smirnov, N; Smirnov, D; Solyst, W; Song, L; Sorensen, P; Spinka, H M; Srivastava, B; Stanislaus, T D S; Stepanov, M; Stock, R; Strikhanov, M; Stringfellow, B; Sumbera, M; Summa, B; Sun, Z; Sun, X M; Sun, Y; Surrow, B; Svirida, D N; Tang, Z; Tang, A H; Tarnowsky, T; Tawfik, A; Thäder, J; Thomas, J H; Timmins, A R; Tlusty, D; Todoroki, T; Tokarev, M; Trentalange, S; Tribble, R E; Tribedy, P; Tripathy, S K; Tsai, O D; Ullrich, T; Underwood, D G; Upsal, I; Van Buren, G; van Nieuwenhuizen, G; Vandenbroucke, M; Varma, R; Vasiliev, A N; Vertesi, R; Videbæk, F; Vokal, S; Voloshin, S A; Vossen, A; Wang, F; Wang, G; Wang, J S; Wang, H; Wang, Y; Wang, Y; Webb, G; Webb, J C; Wen, L; Westfall, G D; Wieman, H; Wissink, S W; Witt, R; Wu, Y; Xiao, Z G; Xie, W; Xie, G; Xin, K; Xu, Y F; Xu, Q H; Xu, N; Xu, H; Xu, Z; Xu, J; Yang, S; Yang, Y; Yang, Y; Yang, C; Yang, Y; Yang, Q; Ye, Z; Ye, Z; Yepes, P; Yi, L; Yip, K; Yoo, I-K; Yu, N; Zbroszczyk, H; Zha, W; Zhang, X P; Zhang, Y; Zhang, J; Zhang, J; Zhang, S; Zhang, S; Zhang, Z; Zhang, J B; Zhao, J; Zhong, C; Zhou, L; Zhu, X; Zoulkarneeva, Y; Zyzak, M

    2016-03-18

    We present results from a harmonic decomposition of two-particle azimuthal correlations measured with the STAR detector in Au+Au collisions for energies ranging from sqrt[s_{NN}]=7.7 to 200 GeV. The third harmonic v_{3}^{2}{2}=⟨cos3(ϕ_{1}-ϕ_{2})⟩, where ϕ_{1}-ϕ_{2} is the angular difference in azimuth, is studied as a function of the pseudorapidity difference between particle pairs Δη=η_{1}-η_{2}. Nonzero v_{3}^{2}{2} is directly related to the previously observed large-Δη narrow-Δϕ ridge correlations and has been shown in models to be sensitive to the existence of a low viscosity quark gluon plasma phase. For sufficiently central collisions, v_{3}^{2}{2} persist down to an energy of 7.7 GeV, suggesting that quark gluon plasma may be created even in these low energy collisions. In peripheral collisions at these low energies, however, v_{3}^{2}{2} is consistent with zero. When scaled by the pseudorapidity density of charged-particle multiplicity per participating nucleon pair, v_{3}^{2}{2} for central collisions shows a minimum near sqrt[s_{NN}]=20  GeV.

  14. NEOCAM: Near Earth Object Chemical Analysis Mission: Bridging the Gulf between Telescopic Observations and the Chemical and Mineralogical Compositions of Asteroids or Diogenes A: Diagnostic Observation of the Geology of Near Earth Spectrally-Classified Asteroids

    NASA Technical Reports Server (NTRS)

    Nuth, Joseph A.

    2009-01-01

    Studies of meteorites have yielded a wealth of scientific information based on highly detailed chemical and isotopic studies possible only in sophisticated terrestrial laboratories. Telescopic studies have revealed an enormous (greater than 10(exp 5)) number of physical objects ranging in size from a few tens of meters to several hundred kilometers, orbiting not only in the traditional asteroid belt between Mars and Jupiter but also throughout the inner solar system. Many of the largest asteroids are classed into taxonomic groups based on their observed spectral properties and are designated as C, D. X, S or V types (as well as a wide range in sub-types). These objects are certainly the sources far the meteorites in our laboratories, but which asteroids are the sources for which meteorites? Spectral classes are nominally correlated to the chemical composition and physical characteristics of the asteroid itself based on studies of the spectral changes induced in meteorites due to exposure to a simulated space environment. While laboratory studies have produced some notable successes (e.g. the identification of the asteroid Vesta as the source of the H, E and D meteorite classes), it is unlikely that we have samples of each asteroidal spectral type in our meteorite collection. The correlation of spectral type and composition for many objects will therefore remain uncertain until we can return samples of specific asteroid types to Earth for analyses. The best candidates for sample return are asteroids that already come close to the Earth. Asteroids in orbit near 1 A.U. have been classified into three groups (Aten, Apollo & Amor) based on their orbital characteristics. These Near Earth Objects (NEOs) contain representatives of virtually all spectral types and sub-types of the asteroid population identified to date. Because of their close proximity to Earth, NEOs are prime targets for asteroid missions such as the NEAR-Shoemaker NASA Discovery Mission to Eros and the

  15. Energy dependent calibration of XR-QA2 radiochromic film with monochromatic and polychromatic x-ray beams

    SciTech Connect

    Di Lillo, F.; Mettivier, G. Sarno, A.; Russo, P.; Tromba, G.; Tomic, N.; Devic, S.

    2016-01-15

    minimum sensitivity of 0.0127 to a maximum sensitivity of 0.0219 at 10 mGy air kerma in air. The more suitable function for air kerma calibration of the XR-QA2 radiochromic film was the power function. A significant batch-to-batch variation, up to 55%, in film response at 120 kV (46.5 keV effective energy) was observed in comparison with published data.

  16. Novel approach for observing the asymmetrical evolution and the compositional nonuniformity of laser pulsed atom probe tomography of a single ZnO nanowire

    NASA Astrophysics Data System (ADS)

    Seol, Jae-Bok; Kim, Young-Tae; Kim, Bo-Hwa; Park, Chan-Gyung

    2016-01-01

    The characterization of ZnO nanowires is crucial for developing nanostructured devices together with related compounds and alloys with an atomic-scale regime. This study describes the effects of laser energy on the atom probe tomography analysis of a single ZnO nanowire with a high aspect ratio, diameters of 80?100 nm and lengths of 10 µm. We observed both an asymmetrical evolution in the apex morphology and the compositional nonuniformities of Zn and O ions with respect to the laser energies ranging from 5 to 40 nJ. When the higher laser illumination exposed to the ZnO nanowires, non-uniform field strength becomes noticeable especially at the laser incident side of the samples. Moreover, we measured the charge state ratios of Zn+ and Zn2+ ions as a function of the applied laser energies. Our results proved important for accurate quantitative characterization and better interpretation for the laser-pulsed atom probe tomography of ZnO-based devices.

  17. Observation and quantification of water penetration into Strain Hardening Cement-based Composites (SHCC) with multiple cracks by means of neutron radiography

    NASA Astrophysics Data System (ADS)

    Zhang, P.; Wittmann, F. H.; Zhao, T. J.; Lehmann, E. H.; Tian, L.; Vontobel, P.

    2010-08-01

    Durability of reinforced concrete structures has become a crucial issue with respect to economy, ecology and sustainability. One major reason for durability problems of concrete structures is the limited strain capacity of cement-based materials under imposed tensile stress. By adding PVA fibers, a new material named Strain Hardening Cement-based Composites (SHCC) with high strain capacity can be produced. Due to the formation of multiple micro-cracks, wide cracks can be avoided in SHCC under an imposed strain. The high strain capacity, however, is beneficial with respect to durability only if the multi-crack formation in SHCC does not lead to significantly increased water penetration. If water and aggressive chemical compounds such as chlorides and sulfates dissolved in water penetrate into the cement-based matrix and reach the steel reinforcement service-life of reinforced concrete structures will be reduced significantly. In this project, neutron radiography was applied to observe and quantify the process of water penetration into uncracked SHCC and after the multi-crack formation. In addition, water penetration into integral water repellent cracked and uncracked SHCC, which has been produced by adding a silane-based water repellent agent to the fresh SHCC mortar has been investigated. Results will be discussed with respect to durability.

  18. Direct Observation on the Evolution of Shear Banding and Buckling in Tungsten Fiber Reinforced Zr-Based Bulk Metallic Glass Composite

    NASA Astrophysics Data System (ADS)

    Chen, J. H.; Chen, Y.; Jiang, M. Q.; Chen, X. W.; Fu, H. M.; Zhang, H. F.; Dai, L. H.

    2014-11-01

    The evolution of micro-damage and deformation of each phase in the composite plays a pivotal role in the clarification of deformation mechanism of composite. However, limited model and mechanical experiments were conducted to reveal the evolution of the deformation of the two phases in the tungsten fiber reinforced Zr-based bulk metallic glass composite. In this study, quasi-static compressive tests were performed on this composite. For the first time, the evolution of micro-damage and deformation of the two phases in this composite, i.e., shear banding of the metallic glass matrix and buckling deformation of the tungsten fiber, were investigated systematically by controlling the loading process at different degrees of deformation. It is found that under uniaxial compression, buckling of the tungsten fiber occurs first, while the metallic glass matrix deforms homogeneously. Upon further loading, shear bands initiate from the fiber/matrix interface and propagate in the metallic glass matrix. Finally, the composite fractures in a mixed mode, with splitting in the tungsten fiber, along with shear fracture in the metallic glass matrix. Through the analysis on the stress state in the composite and resistance to shear banding of the two phases during compressive deformation, the possible deformation mechanism of the composite is unveiled. The deformation map of the composite, which covers from elastic deformation to final fracture, is obtained as well.

  19. Observations of Vertical Gradients in Composition, Oxidation States, and Diurnal Dynamics for a Comprehensive Suite of VOCs from 10 to 525 m in the San Joaquin Valley, California

    NASA Astrophysics Data System (ADS)

    Misztal, P. K.; Weber, R.; Guha, A.; Seco, R.; Kim, S.; Guenther, A. B.; Goldstein, A. H.

    2015-12-01

    Volatile organic compounds (VOCs) are emitted by numerous anthropogenic and biogenic sources and undergo oxidative processing, as well as horizontal and vertical transport, in the troposphere. Understanding the dynamics of chemical and physical land atmosphere exchange processes and their impacts on atmospheric chemistry requires high temporal resolution of observations at multiple heights and the knowledge of the sources and sinks. We measured dynamic composition changes of VOCs as a function of height (5 inlets from 10 to 525 m, switching every 2 minutes, full profile every 10 minutes) for more than a year using a PTR-QMS. Here, we focus on a multi-week period in February 2013 when simultaneous SRI-TOFMS and PTR-QMS took place. More than 300 ions were detected within an m/z range of 0.000 - 400.000 Th and 260 ions were analyzed. Chemical formulas were assigned to more than 50% of these ions. Late winter is a period when anthropogenic influences are relatively high including remote sources in the Central Valley. Biogenic influences are low at this time of year, but were clearly observed. The average diurnal vertical gradients (Figure 1) showed trends and patterns and behavior consistent with boundary layer dynamics, wind profiles and source activity for a broad array of VOCs and source categories. Mass concentration of oxygenated VOCs with 2, 3 or more oxygens or with nitrogen+oxygen had an increasing tendency with height. The opposite was true for pure hydrocarbons and reduced nitrogen containing VOCs which generally decrease with height. The remaining species comprised halogenated as well as other volatile products. Average oxidation state ranged from -2.0 to 4.3. These observations are useful to reflect the dynamics of VOCs at a rural site in the Central Valley and could be particularly useful for comparison with models of atmospheric chemistry that include PBL dynamics. Figure 1: Gradient concentration diurnal profiles for 48 selected ions, showing the

  20. In situ vertical profiles of aerosol extinction, mass, and composition over the southeast United States during SENEX and SEAC4RS: observations of a modest aerosol enhancement aloft

    NASA Astrophysics Data System (ADS)

    Wagner, N. L.; Brock, C. A.; Angevine, W. M.; Beyersdorf, A.; Campuzano-Jost, P.; Day, D.; de Gouw, J. A.; Diskin, G. S.; Gordon, T. D.; Graus, M. G.; Holloway, J. S.; Huey, G.; Jimenez, J. L.; Lack, D. A.; Liao, J.; Liu, X.; Markovic, M. Z.; Middlebrook, A. M.; Mikoviny, T.; Peischl, J.; Perring, A. E.; Richardson, M. S.; Ryerson, T. B.; Schwarz, J. P.; Warneke, C.; Welti, A.; Wisthaler, A.; Ziemba, L. D.; Murphy, D. M.

    2015-06-01

    Vertical profiles of submicron aerosol from in situ aircraft-based measurements were used to construct aggregate profiles of chemical, microphysical, and optical properties. These vertical profiles were collected over the southeastern United States (SEUS) during the summer of 2013 as part of two separate field studies: the Southeast Nexus (SENEX) study and the Study of Emissions and Atmospheric Composition, Clouds, and Climate Coupling by Regional Surveys (SEAC4RS). Shallow cumulus convection was observed during many profiles. These conditions enhance vertical transport of trace gases and aerosol and create a cloudy transition layer on top of the sub-cloud mixed layer. The trace gas and aerosol concentrations in the transition layer were modeled as a mixture with contributions from the mixed layer below and the free troposphere above. The amount of vertical mixing, or entrainment of air from the free troposphere, was quantified using the observed mixing ratio of carbon monoxide (CO). Although the median aerosol mass, extinction, and volume decreased with altitude in the transition layer, they were ~10 % larger than expected from vertical mixing alone. This enhancement was likely due to secondary aerosol formation in the transition layer. Although the transition layer enhancements of the particulate sulfate and organic aerosol (OA) were both similar in magnitude, only the enhancement of sulfate was statistically significant. The column integrated extinction, or aerosol optical depth (AOD), was calculated for each individual profile, and the transition layer enhancement of extinction typically contributed less than 10 % to the total AOD. Our measurements and analysis were motivated by two recent studies that have hypothesized an enhanced layer of secondary aerosol aloft to explain the summertime enhancement of AOD (2-3 times greater than winter) over the southeastern United States. The first study attributes the layer aloft to secondary organic aerosol (SOA) while

  1. Adsorption site of c(2×2) O on Ni(0001): An off-normal-direction energy-dependent photoelectron-diffraction study

    NASA Astrophysics Data System (ADS)

    Mei, W. N.; Tong, S. Y.

    1986-01-01

    We have used the technique of energy-dependent photoelectron diffraction (EDPD) to study the pseudo-bridge-site model proposed by Demuth et al. for the adsorption of c(2×2) O on Ni(001). Calculated EDPD curves at the normal exit direction for the pseudo-bridge site, averaged over four domains, were compared with those for the fourfold hollow site. We found no significant differences in the EDPD curves for the two different structural models. However, the calculated EDPD curves at off-normal directions, such as those along the [011] direction, or along the O-Ni bond directions, were qualitatively different for the two sites. We therefore conclude that off-normal-direction EDPD curves, when compared with measured data, can effectively determine the lateral coordinates of the oxygen overlayer on Ni(001).

  2. Energy dependence of transverse momentum fluctuations in Pb+Pb collisions at the CERN Super Proton Synchrotron (SPS) at 20A to 158A GeV

    SciTech Connect

    NA49 Collaboration; Anticic, T.

    2009-04-15

    Results are presented on event-by-event fluctuations of transverse momenta p{sub T} in central Pb+Pb interactions at 20A, 30A, 40A, 80A, and 158A GeV. The analysis was performed for charged particles at forward center-of-mass rapidity (1.1 < y*{sub {pi}} < 2.6). Three fluctuation measures were studied: the distribution of average transverse momentum M(p{sub T}) in the event, the {phi}{sub p{sub T}} fluctuation measure, and two-particle transverse momentum correlations. Fluctuations of p{sub T} are small and show no significant energy dependence in the energy range of the CERN Super Proton Synchrotron. Results are compared with QCD-inspired predictions for the critical point, and with the UrQMD model. Transverse momentum fluctuations, similar to multiplicity fluctuations, do not show the increase expected for freeze-out near the critical point of QCD.

  3. Modelling of OPNMR phenomena using photon energy-dependent 〈Sz〉 in GaAs and InP.

    PubMed

    Wheeler, Dustin D; Willmering, Matthew M; Sesti, Erika L; Pan, Xingyuan; Saha, Dipta; Stanton, Christopher J; Hayes, Sophia E

    2016-12-01

    We have modified the model for optically-pumped NMR (OPNMR) to incorporate a revised expression for the expectation value of the z-projection of the electron spin, 〈Sz〉 and apply this model to both bulk GaAs and a new material, InP. This expression includes the photon energy dependence of the electron polarization when optically pumping direct-gap semiconductors in excess of the bandgap energy, Eg. Rather than using a fixed value arising from coefficients (the matrix elements) for the optical transitions at the k=0 bandedge, we define a new parameter, Sopt(Eph). Incorporating this revised element into the expression for 〈Sz〉, we have simulated the photon energy dependence of the OPNMR signals from bulk semi-insulating GaAs and semi-insulating InP. In earlier work, we matched calculations of electron spin polarization (alone) to features in a plot of OPNMR signal intensity versus photon energy for optical pumping (Ramaswamy et al., 2010). By incorporating an electron spin polarization which varies with pump wavelength into the penetration depth model of OPNMR signal, we are able to model features in both III-V semiconductors. The agreement between the OPNMR data and the corresponding model demonstrates that fluctuations in the OPNMR intensity have particular sensitivity to light hole-to-conduction band transitions in bulk systems. We provide detailed plots of the theoretical predictions for optical pumping transition probabilities with circularly-polarized light for both helicities of light, broken down into illustrative plots of optical magnetoabsorption and spin polarization, shown separately for heavy-hole and light-hole transitions. These plots serve as an effective roadmap of transitions, which are helpful to other researchers investigating optical pumping effects.

  4. The role of the metastable O2(b{{}^{1}}{\\Sigma}_{\\text {g}}^{+} ) and energy-dependent secondary electron emission yields in capacitively coupled oxygen discharges

    NASA Astrophysics Data System (ADS)

    Hannesdottir, H.; Gudmundsson, J. T.

    2016-10-01

    The effects of including the singlet metastable molecule O2(b{{}1}Σ\\text{g}+ ) in the discharge model of a capacitively coupled rf driven oxygen discharge are explored. We furthermore examine the addition of energy-dependent secondary electron emission yields from the electrodes to the discharge model. The one-dimensional object-oriented particle-in-cell Monte Carlo collision code oopd1 is used for this purpose, with the oxygen discharge model considering the species {{\\text{O}}2}≤ft({{\\text{X}}3}Σ\\text{g}-\\right) , {{\\text{O}}2}≤ft({{\\text{a}}1}{{Δ }\\text{g}}\\right) , {{\\text{O}}2}≤ft({{\\text{b}}1}Σ\\text{g}+\\right) , O(3P), O(1D), \\text{O}2+ , O+, O-, and electrons. The effects on particle density profiles, the electron heating rate profile, the electron energy probability function and the sheath width are explored including and excluding the metastable oxygen molecules and secondary electron emission. Earlier we have demonstrated that adding the metastable O2(a{{}1}{{Δ }\\text{g}} ) to the discharge model changes the electron heating from having contributions from both bulk and sheath heating to being dominated by sheath heating for pressures above 50 mTorr. We find that including the metastable O2(b{{}1}Σ\\text{g}+ ) further decreases the ohmic heating and the effective electron temperature in the bulk region. The effective electron temperature in the electronegative core is found to be less than 1 eV in the pressure range 50-200 mTorr which agrees with recent experimental findings. Furthermore, we find that including an energy-dependent secondary electron emission yield for \\text{O}2+ -ions has a significant influence on the discharge properties, including decreased sheath width.

  5. Experimental Observations for Determining the Maximum Torque Values to Apply to Composite Components Mechanically Joined With Fasteners (MSFC Center Director's Discretionary Fund Final Report, Proj. 03-13}

    NASA Technical Reports Server (NTRS)

    Thomas, F. P.

    2006-01-01

    Aerospace structures utilize innovative, lightweight composite materials for exploration activities. These structural components, due to various reasons including size limitations, manufacturing facilities, contractual obligations, or particular design requirements, will have to be joined. The common methodologies for joining composite components are the adhesively bonded and mechanically fastened joints and, in certain instances, both methods are simultaneously incorporated into the design. Guidelines and recommendations exist for engineers to develop design criteria and analyze and test composites. However, there are no guidelines or recommendations based on analysis or test data to specify a torque or torque range to apply to metallic mechanical fasteners used to join composite components. Utilizing the torque tension machine at NASA s Marshall Space Flight Center, an initial series of tests were conducted to determine the maximum torque that could be applied to a composite specimen. Acoustic emissions were used to nondestructively assess the specimens during the tests and thermographic imaging after the tests.

  6. Po-Basin Atmospheric Composition during the Pegasos Field Campaign (summer 2012): Evaluation of ninfa/aodeM Simulation with In-Situ e Remote Sensing Observations

    NASA Astrophysics Data System (ADS)

    Landi, Tony C.; Bonafe, Giovanni; Stortini, Michele; Minguzzi, Enrico; Cristofanelli, Paolo; Marinoni, Angela; Giulianelli, Lara; Sandrini, Silvia; Gilardoni, Stefania; Rinaldi, Matteo; Ricciardelli, Isabella

    2014-05-01

    Within the EU project PEGASOS one of three field campaigns took place in the Po Valley during the summer of 2012. Photochemistry, particle formation, and particle properties related to diurnal evolution of the PBL were investigated through both in-situ and airborne measurements on board a Zeppelin NT air ship. In addition, 3-D air quality modeling systems were implemented over the Po valley for the summer 2012 to better characterize the atmospheric conditions, in terms of meteorological parameters and chemical composition. In this work, we present a comparison between atmospheric composition simulations carried out by the modeling system NINFA/AODEM with measurements performed during the PEGASOS field campaign for the period 13 June - 12 July 2012. NINFA (Stortini et al., 2007) is based on the chemical transport model CHIMERE (Bessagnet et al., 2008), driven by COSMO-I7, the meteorological Italian Limited Area Model, (Steppeler et al., 2003). Boundary conditions are provided by Prev'air data (www.prevair.org), and emission data input are based on regional, national and European inventory. Besides, a post-processing tool for aerosol optical properties calculation, called AODEM (Landi T. C. 2013) was implemented. Thus, predictions of Aerosol Optical Depth and aerosol extinction coefficient were also used for model comparison to vertical-resolved observations. For this experiment, NINFA/AODEM has been also evaluated by using measurements of size-segregated aerosol samples, number particles concentration and aerosol optical properties collected on hourly basis at the 3 different sampling sites representative of urban background (Bologna), rural background (San Pietro Capofiume) and remote high altitude station (Monte Cimone 2165 ma.s.l.). ). In addition, we focused on new particles formations events and long range transports from Northern Africa observed during the field campaign. References Bessagnet, Bertrand, Laurent Menut, Gabriele Curci, Alma Hodzic, Bruno

  7. Energy Dependence of Fission Product Yields from {sup 235}U, {sup 238}U and {sup 239}Pu for Incident Neutron Energies Between 0.5 and 14.8 MeV

    SciTech Connect

    Gooden, M.E.; Arnold, C.W.; Becker, J.A.; Bhatia, C.; Bhike, M.; Bond, E.M.; Bredeweg, T.A.; Fallin, B.; Fowler, M.M.; Howell, C.R.; Kelley, J.H.; Krishichayan; Macri, R.; Rusev, G.; Ryan, C.; Sheets, S.A.; Stoyer, M.A.; Tonchev, A.P.; Tornow, W.; and others

    2016-01-15

    Fission Product Yields (FPY) have historically been one of the most observable features of the fission process. They are known to have strong variations that are dependent on the fissioning species, the excitation energy, and the angular momentum of the compound system. However, consistent and systematic studies of the variation of these FPY with energy have proved challenging. This is caused primarily by the nature of the experiments that have traditionally relied on radiochemical procedures to isolate specific fission products. Although radiochemical procedures exist that can isolate all products, each element presents specific challenges and introduces varying degrees of systematic errors that can make inter-comparison of FPY uncertain. Although of high importance in fields such as nuclear forensics and Stockpile Stewardship, accurate information about the energy dependence of neutron induced FPY are sparse, due primarily to the lack of suitable monoenergetic neutron sources. There is a clear need for improved data, and to address this issue, a collaboration was formed between Los Alamos National Laboratory (LANL), Lawrence Livermore National Laboratory (LLNL) and the Triangle Universities Nuclear Laboratory (TUNL) to measure the energy dependence of FPY for {sup 235}U, {sup 238}U and {sup 239}Pu. The measurements have been performed at TUNL, using a 10 MV Tandem Van de Graaff accelerator to produce monoenergetic neutrons at energies between 0.6 MeV to 14.8 MeV through a variety of reactions. The measurements have utilized a dual-fission chamber, with thin (10-100 μg/cm2) reference foils of similar material to a thick (100-400 mg) activation target held in the center between the chambers. This method allows for the accurate determination of the number of fissions that occurred in the thick target without requiring knowledge of the fission cross section or neutron fluence on target. Following activation, the thick target was removed from the dual-fission chamber

  8. Energy Dependence of Fission Product Yields from 235U, 238U and 239Pu for Incident Neutron Energies Between 0.5 and 14.8 MeV

    NASA Astrophysics Data System (ADS)

    Gooden, M. E.; Arnold, C. W.; Becker, J. A.; Bhatia, C.; Bhike, M.; Bond, E. M.; Bredeweg, T. A.; Fallin, B.; Fowler, M. M.; Howell, C. R.; Kelley, J. H.; Krishichayan; Macri, R.; Rusev, G.; Ryan, C.; Sheets, S. A.; Stoyer, M. A.; Tonchev, A. P.; Tornow, W.; Vieira, D. J.; Wilhelmy, J. B.

    2016-01-01

    Fission Product Yields (FPY) have historically been one of the most observable features of the fission process. They are known to have strong variations that are dependent on the fissioning species, the excitation energy, and the angular momentum of the compound system. However, consistent and systematic studies of the variation of these FPY with energy have proved challenging. This is caused primarily by the nature of the experiments that have traditionally relied on radiochemical procedures to isolate specific fission products. Although radiochemical procedures exist that can isolate all products, each element presents specific challenges and introduces varying degrees of systematic errors that can make inter-comparison of FPY uncertain. Although of high importance in fields such as nuclear forensics and Stockpile Stewardship, accurate information about the energy dependence of neutron induced FPY are sparse, due primarily to the lack of suitable monoenergetic neutron sources. There is a clear need for improved data, and to address this issue, a collaboration was formed between Los Alamos National Laboratory (LANL), Lawrence Livermore National Laboratory (LLNL) and the Triangle Universities Nuclear Laboratory (TUNL) to measure the energy dependence of FPY for 235U, 238U and 239Pu. The measurements have been performed at TUNL, using a 10 MV Tandem Van de Graaff accelerator to produce monoenergetic neutrons at energies between 0.6 MeV to 14.8 MeV through a variety of reactions. The measurements have utilized a dual-fission chamber, with thin (10-100 μg/cm2) reference foils of similar material to a thick (100-400 mg) activation target held in the center between the chambers. This method allows for the accurate determination of the number of fissions that occurred in the thick target without requiring knowledge of the fission cross section or neutron fluence on target. Following activation, the thick target was removed from the dual-fission chamber and gamma

  9. Energy dependence of fission product yields from 235U, 238U and 239Pu for incident neutron energies between 0.5 and 14.8 MeV

    DOE PAGES

    Gooden, M. E.; Arnold, C. W.; Becker, J. A.; ...

    2016-01-06

    In this study, Fission Product Yields (FPY) have historically been one of the most observable features of the fission process. They are known to have strong variations that are dependent on the fissioning species, the excitation energy, and the angular momentum of the compound system. However, consistent and systematic studies of the variation of these FPY with energy have proved challenging. This is caused primarily by the nature of the experiments that have traditionally relied on radiochemical procedures to isolate specific fission products. Although radiochemical procedures exist that can isolate all products, each element presents specific challenges and introduces varyingmore » degrees of systematic errors that can make inter-comparison of FPY uncertain. Although of high importance in fields such as nuclear forensics and Stockpile Stewardship, accurate information about the energy dependence of neutron induced FPY are sparse, due primarily to the lack of suitable monoenergetic neutron sources. There is a clear need for improved data, and to address this issue, a collaboration was formed between Los Alamos National Laboratory (LANL), Lawrence Livermore National Laboratory (LLNL) and the Triangle Universities Nuclear Laboratory (TUNL) to measure the energy dependence of FPY for 235U, 238U and 239Pu. The measurements have been performed at TUNL, using a 10 MV Tandem Van de Graaff accelerator to produce monoenergetic neutrons at energies between 0.6 MeV to 14.8 MeV through a variety of reactions. The measurements have utilized a dual-fission chamber, with thin (10-100 μg/cm2) reference foils of similar material to a thick (100-400 mg) activation target held in the center between the chambers. This method allows for the accurate determination of the number of fissions that occurred in the thick target without requiring knowledge of the fission cross section or neutron fluence on target. Following activation, the thick target was removed from the dual

  10. Energy dependence of fission product yields from 235U, 238U and 239Pu for incident neutron energies between 0.5 and 14.8 MeV

    SciTech Connect

    Gooden, M. E.; Arnold, C. W.; Becker, J. A.; Bhatia, C.; Bhike, M.; Bond, E. M.; Bredeweg, T. A.; Fallin, B.; Fowler, M. M.; Howell, C. R.; Kelley, J. H.; Krishichayan, .; Macri, R.; Rusev, G.; Ryan, C.; Sheets, S. A.; Stoyer, M. A.; Tonchev, A. P.; Tornow, W.; Vieira, D. J.; Wilhelmy, J. B.

    2016-01-06

    In this study, Fission Product Yields (FPY) have historically been one of the most observable features of the fission process. They are known to have strong variations that are dependent on the fissioning species, the excitation energy, and the angular momentum of the compound system. However, consistent and systematic studies of the variation of these FPY with energy have proved challenging. This is caused primarily by the nature of the experiments that have traditionally relied on radiochemical procedures to isolate specific fission products. Although radiochemical procedures exist that can isolate all products, each element presents specific challenges and introduces varying degrees of systematic errors that can make inter-comparison of FPY uncertain. Although of high importance in fields such as nuclear forensics and Stockpile Stewardship, accurate information about the energy dependence of neutron induced FPY are sparse, due primarily to the lack of suitable monoenergetic neutron sources. There is a clear need for improved data, and to address this issue, a collaboration was formed between Los Alamos National Laboratory (LANL), Lawrence Livermore National Laboratory (LLNL) and the Triangle Universities Nuclear Laboratory (TUNL) to measure the energy dependence of FPY for 235U, 238U and 239Pu. The measurements have been performed at TUNL, using a 10 MV Tandem Van de Graaff accelerator to produce monoenergetic neutrons at energies between 0.6 MeV to 14.8 MeV through a variety of reactions. The measurements have utilized a dual-fission chamber, with thin (10-100 μg/cm2) reference foils of similar material to a thick (100-400 mg) activation target held in the center between the chambers. This method allows for the accurate determination of the number of fissions that occurred in the thick target without requiring knowledge of the fission cross section or neutron fluence on target. Following activation, the thick target was removed

  11. Energy dependence of the spin excitation anisotropy in uniaxial-strained BaFe1.9Ni0.1As2

    SciTech Connect

    Song, Yu; Lu, Xingye; Abernathy, Douglas L.; Tam, David W.; Niedziela, Jennifer L.; Tian, Wei; Si, Qimiao; Dai, Pengcheng; Luo, Huiqian

    2015-11-06

    In this study, we use inelastic neutron scattering to study the temperature and energy dependence of the spin excitation anisotropy in uniaxial-strained electron-doped iron pnictide BaFe1.9Ni0.1As2 near optimal superconductivity (Tc = 20K). Our work has been motivated by the observation of in-plane resistivity anisotropy in the paramagnetic tetragonal phase of electron-underdoped iron pnictides under uniaxial pressure, which has been attributed to a spin-driven Ising-nematic state or orbital ordering. Here we show that the spin excitation anisotropy, a signature of the spin-driven Ising-nematic phase, exists for energies below 60 meV in uniaxial-strained BaFe1.9Ni0.1As2. Since this energy scale is considerably larger than the energy splitting of the dxz and dyz bands of uniaxial-strained Ba(Fe1–xCox)2As2 near optimal superconductivity, spin Ising-nematic correlations are likely the driving force for the resistivity anisotropy and associated electronic nematic correlations.

  12. Energy dependence of the electron-boson coupling strength in the electron-doped cuprate superconductor Pr1.85Ce0.15CuO4 -δ

    NASA Astrophysics Data System (ADS)

    Beck, M.; Klammer, M.; Rousseau, I.; Obergfell, M.; Leiderer, P.; Helm, M.; Kabanov, V. V.; Diamant, I.; Rabinowicz, A.; Dagan, Y.; Demsar, J.

    2017-02-01

    The quest for a pairing boson in cuprate high-temperature superconductors is one of the outstanding tasks of solid-state physics. Numerous time-resolved studies of pair breaking, related to pairing by time-reversal symmetry, have been performed using femtosecond optical pulses. By considering energy relaxation pathways between charge, spin, and lattice degrees of freedom, evidence for both phonon and antiferromagnetic fluctuation-mediated pairing has been obtained. Here we present a study of the superconducting-state depletion process in an electron-doped cuprate Pr1.85Ce0.15CuO4 -δ , where the superconducting gap is smaller than the energy of relevant bosonic excitations. When pumping with above-gap terahertz pulses, we find that the absorbed energy density required to deplete superconductivity, Adep, matches the thermodynamic condensation energy. On the contrary, by near-infrared pumping, Adep is an order of magnitude higher, as in the case of hole-doped, large-gap cuprates. These results imply that only a small subset of bosons, which are generated during the relaxation of optically excited carriers, contributes to pairing. This observation implies that, contrary to the common assumptions, electron-boson coupling in cuprates is strongly energy dependent.

  13. Chemical composition and severe ozone loss derived from SCIAMACHY and GOME-2 observations during Arctic winter 2010/2011 in comparisons to Arctic winters in the past

    NASA Astrophysics Data System (ADS)

    Hommel, R.; Eichmann, K.-U.; Aschmann, J.; Bramstedt, K.; Weber, M.; von Savigny, C.; Richter, A.; Rozanov, A.; Wittrock, F.; Bauer, R.; Khosrawi, F.; Burrows, J. P.

    2013-06-01

    Record breaking losses of ozone (O3) in the Arctic stratosphere have been reported in winter and spring 2011. Trace gas amounts and polar stratospheric cloud (PSC) distributions retrieved using differential optical absorption spectroscopy (DOAS) and scattering theory applied to the measurements of radiance and irradiance by satellite-born and ground-based instrumentation, document the unusual behaviour. A chemical transport model has been used to relate and compare Arctic winter-spring conditions in 2011 with those in previous years. We examine in detail the composition and transformations occurring in the Arctic polar vortex using total column and vertical profile data products for O3, bromine oxide (BrO), nitrogen dioxide (NO2), chlorine dioxide (OClO), and PSCs retrieved from measurements made by the instrument SCIAMACHY onboard the ESA satellite Envisat, as well as the total column ozone amount, retrieved from the measurements of GOME-2 on the EUMETSAT operational meteorological polar orbiter Metop-A. In the late winter and spring 2010/2011 the chemical loss of O3 in the polar vortex is consistent with and confirms findings reported elsewhere. More than 70% of O3 was depleted between the 425 K and 525 K isentropic surfaces, i.e. in the altitude range ~16-20 km. In contrast, during the same period in the previous winter only slightly more than 20% depletion occurred below 20 km, whereas 40% of the O3 was removed above the 575 K isentrope (~23 km). This loss above the 575 K isentrope is explained by the catalytic destruction by the NOx descending from the mesosphere. At lower altitudes O3 loss results from processing by halogen driven O3 catalytic removal cycles, activated by the large volume of PSC generated throughout this winter and spring. The mid-winter 2011 conditions, prior to the catalytic cycles being fully effective, are also investigated. Surprisingly, a significant loss of O3 with 60% is observed in mid-January 2011 below 500 K (~19 km), which was

  14. The compositional evolution of C/2012 S1 (ISON) from ground-based high-resolution infrared spectroscopy as part of a worldwide observing campaign

    NASA Astrophysics Data System (ADS)

    Dello Russo, N.; Vervack, R. J.; Kawakita, H.; Cochran, A.; McKay, A. J.; Harris, W. M.; Weaver, H. A.; Lisse, C. M.; DiSanti, M. A.; Kobayashi, H.; Biver, N.; Bockelée-Morvan, D.; Crovisier, J.; Opitom, C.; Jehin, E.

    2016-03-01

    Volatile production rates, relative abundances, rotational temperatures, and spatial distributions in the coma were measured in C/2012 S1 (ISON) using long-slit high-dispersion (λ/Δλ ∼ 2.5 × 104) infrared spectroscopy as part of a worldwide observing campaign. Spectra were obtained on UT 2013 October 26 and 28 with NIRSPEC at the W.M. Keck Observatory, and UT 2013 November 19 and 20 with CSHELL at the NASA IRTF. H2O was detected on all dates, with production rates increasing markedly from (8.7 ± 1.5) × 1027 molecules s-1 on October 26 (Rh = 1.12 AU) to (3.7 ± 0.4) × 1029 molecules s-1 on November 20 (Rh = 0.43 AU). Short-term variability of H2O production is also seen as observations on November 19 show an increase in H2O production rate of nearly a factor of two over a period of about 6 h. C2H6, CH3OH and CH4 abundances in ISON are slightly depleted relative to H2O when compared to mean values for comets measured at infrared wavelengths. On the November dates, C2H2, HCN and OCS abundances relative to H2O appear to be within the range of mean values, whereas H2CO and NH3 were significantly enhanced. There is evidence that the abundances with respect to H2O increased for some species but not others between October 28 (Rh = 1.07 AU) and November 19 (Rh = 0.46 AU). The high mixing ratios of H2CO/CH3OH and C2H2/C2H6 on November 19, and changes in the mixing ratios of some species with respect to H2O between October 28 to November 19, indicates compositional changes that may be the result of a transition from sampling radiation-processed outer layers in this dynamically new comet to sampling more pristine natal material as the outer processed layer was increasingly eroded and the thermal wave propagated into the nucleus as the comet approached perihelion for the first time. On November 19 and 20, the spatial distribution for dust appears asymmetric and enhanced in the antisolar direction, whereas spatial distributions for volatiles (excepting CN) appear

  15. The Compositional Evolution of C/2012 S1 (ISON) from Ground-Based High-Resolution Infrared Spectroscopy as Part of a Worldwide Observing Campaign

    NASA Technical Reports Server (NTRS)

    Russo, N. Dello; Vervack, R. J., Jr.; Kawakita, H.; Cochran, A.; McKay, A. J.; Harris, W. M.; Weaver, H.A.; Lisse, C. M.; DiSanti, M. A.; Kobayashi, H.

    2015-01-01

    Volatile production rates, relative abundances, rotational temperatures, and spatial distributions in the coma were measured in C/2012 S1 (ISON) using long-slit high-dispersion (lambda/delta lambda approximately 2.5 times 10 (sup 4)) infrared spectroscopy as part of a worldwide observing campaign. Spectra were obtained on Universal Time 2013 October 26 and 28 with NIRSPEC (Near Infrared Spectrometer) at the W.M. Keck Observatory, and Universal Time 2013 November 19 and 20 with CSHELL (Cryogenic Echelle Spectrograph) at the NASA IRTF (Infrared Telescope Facility). H2O was detected on all dates, with production rates increasing markedly from (8.7 plus or minus 1.5) times 10 (sup 27) molecules per second on October 26 (Heliocentric Distance = 1.12 Astronomical Units) to (3.7 plus or minus 0.4) times 10 (sup 29) molecules per second on November 20 (Heliocentric Distance = 0.43 Astronomical Units). Short-term variability of H2O production is also seen as observations on November 19 show an increase in H2O production rate of nearly a factor of two over a period of about 6 hours. C2H6, CH3OH and CH4 abundances in ISON (International Scientific Optical Network) are slightly depleted relative to H2O when compared to mean values for comets measured at infrared wavelengths. On the November dates, C2H2, HCN and OCS abundances relative to H2O appear to be within the range of mean values, whereas H2CO and NH3 were significantly enhanced. There is evidence that the abundances with respect to H2O increased for some species but not others between October 28 (Heliocentric Distance = 1.07 Astronomical Units) and November 19 (Heliocentric Distance = 0.46 Astronomical Units). The high mixing ratios of H2CO to CH3OH and C2H2 to C2H6 on November 19, and changes in the mixing ratios of some species with respect to H2O between October 28 to November 19, indicates compositional changes that may be the result of a transition from sampling radiation-processed outer layers in this dynamically

  16. Communication: Energy-dependent resonance broadening in symmetric and asymmetric molecular junctions from an ab initio non-equilibrium Green's function approach

    SciTech Connect

    Liu, Zhen-Fei; Neaton, Jeffrey B.

    2014-10-07

    The electronic structure of organic-inorganic interfaces often features resonances originating from discrete molecular orbitals coupled to continuum lead states. An example is molecular junction, individual molecules bridging electrodes, where the shape and peak energy of such resonances dictate junction conductance, thermopower, I-V characteristics, and related transport properties. In molecular junctions where off-resonance coherent tunneling dominates transport, resonance peaks in the transmission function are often assumed to be Lorentzian functions with an energy-independent broadening parameter Γ. Here we define a new energy-dependent resonance broadening function, Γ(E), based on diagonalization of non-Hermitian matrices, which can describe resonances of a more complex, non-Lorentzian nature and can be decomposed into components associated with the left and right leads, respectively. We compute this quantity via an ab initio non-equilibrium Green's function (NEGF) approach based on density functional theory (DFT) for both symmetric and asymmetric molecular junctions, and show that our definition of Γ(E), when combined with Breit-Wigner formula, reproduces the transmission calculated from DFT-NEGF. Through a series of examples, we illustrate how this approach can shed new light on experiments and understanding of junction transport properties in terms of molecular orbitals.

  17. The human prothrombin kringle-2 derived peptide, NSA9, is internalized into bovine capillary endothelial cells through endocytosis and energy-dependent pathways

    SciTech Connect

    Hwang, Hyun Sook; Kim, Soung Soo . E-mail: kimss518@yonsei.ac.kr

    2005-09-23

    Human prothrombin kringle-2 and its partial peptide, NSA9 (NSAVQLVEN), have been reported to have potent anti-angiogenic activities. Here, the internalization mechanism of NSA9 into bovine capillary endothelial (BCE) cells was examined using lactate dehydrogenase (LDH) release assay, fluorescence microscopy, and flow cytometry. LDH release assay results suggested that the integrity of the BCE cell membrane was unaffected by NSA9. Fluorescence microscopy indicated that internalized NSA9 was localized in the cytoplasm around the nucleus, and showed a punctuated fluorescence pattern, which is indicative of endocytic vesicles. Also, the cellular internalization of NSA9 is significantly inhibited by depletion of the cellular ATP pool, endocytosis inhibitors such as chloroquine and nocodazole, and incubation at low temperature (4 deg C). In addition, the anti-proliferative activity of NSA9 against BCE cells was diminished in the presence of endocytosis or metabolic inhibitors. In conclusion, these results strongly suggest that NSA9 might exert its anti-proliferative activity through internalization into BCE cells by endocytosis and energy-dependent pathways.

  18. Collision energy dependence of state-to-state differential cross sections for rotationally inelastic scattering of H2O by He.

    PubMed

    Sarma, Gautam; Saha, Ashim Kumar; Bishwakarma, Chandan Kumar; Scheidsbach, Roy; Yang, Chung-Hsin; Parker, David; Wiesenfeld, Laurent; Buck, Udo; Mavridis, Lazaros; Marinakis, Sarantos

    2017-02-08

    The inelastic scattering of H2O by He as a function of collision energy in the range 381 cm(-1) to 763 cm(-1) at an energy interval of approximately 100 cm(-1) has been investigated in a crossed beam experiment using velocity map imaging. Change in collision energy was achieved by varying the collision angle between the H2O and He beam. We measured the state-to-state differential cross section (DCS) of scattered H2O products for the final rotational states JKaKc = 110, 111, 221 and 414. Rotational excitation of H2O is probed by (2 + 1) resonance enhanced multiphoton ionization (REMPI) spectroscopy. DCS measurements over a wide range of collision energies allowed us to probe the H2O-He potential energy surface (PES) with greater detail than in previous work. We found that a classical approximation of rotational rainbows can predict the collision energy dependence of the DCS. Close-coupling quantum mechanical calculations were used to produce DCS and partial cross sections. The forward-backward ratio (FBR), is introduced here to compare the experimental and theoretical DCS. Both theory and experiments suggest that an increase in the collision energy is accompanied with more forward scattering.

  19. Energy-dependent uptake of benzo[a]pyrene and its cytoskeleton-dependent intracellular transport by the telluric fungus Fusarium solani.

    PubMed

    Fayeulle, Antoine; Veignie, Etienne; Slomianny, Christian; Dewailly, Etienne; Munch, Jean-Charles; Rafin, Catherine

    2014-03-01

    In screening indigenous soil filamentous fungi for polycyclic aromatic hydrocarbons (PAHs) degradation, an isolate of the Fusarium solani was found to incorporate benzo[a]pyrene (BaP) into fungal hyphae before degradation and mineralization. The mechanisms involved in BaP uptake and intracellular transport remain unresolved. To address this, the incorporation of two PAHs, BaP, and phenanthrene (PHE) were studied in this fungus. The fungus incorporated more BaP into cells than PHE, despite the 400-fold higher aqueous solubility of PHE compared with BaP, indicating that PAH incorporation is not based on a simple diffusion mechanism. To identify the mechanism of BaP incorporation and transport, microscopic studies were undertaken with the fluorescence probes Congo Red, BODIPY®493/503, and FM®4-64, targeting different cell compartments respectively fungal cell walls, lipids, and endocytosis. The metabolic inhibitor sodium azide at 100 mM totally blocked BaP incorporation into fungal cells indicating an energy-requirement for PAH uptake into the mycelium. Cytochalasins also inhibited BaP uptake by the fungus and probably its intracellular transport into fungal hyphae. The perfect co-localization of BaP and BODIPY reveals that lipid bodies constitute the intracellular storage sites of BaP in F. solani. Our results demonstrate an energy-dependent uptake of BaP and its cytoskeleton-dependent intracellular transport by F. solani.

  20. Energy Dependence of Neutron-Induced Fission Product Yields of 235U, 238U and 239Pu Between 0.5 and 14.8 MeV

    NASA Astrophysics Data System (ADS)

    Gooden, Matthew; Tornow, Werner; Tonchev, Anton; Vieira, Dave; Wilhelmy, Jerry; Arnold, Charles; Fowler, Malcolm; Stoyer, Mark

    2014-09-01

    Under a joint collaboration between TUNL-LANL-LLNL, a set of absolute fission product yield measurements have been performed. The energy dependence of a number of cumulative fission products between 0.5 and 14.8 MeV have been measured using quasi-monoenergetic neutron beams for three actinide targets, 235U, 238U and 239Pu, between 0.5 and 14.8 MeV. The FPYs were measured by a combination of activation utilizing specially designed dual-fission chambers and γ-ray counting. The dual-fission chambers are back-to-back ionization chambers encasing a target with thin deposits of the same target isotope in each chamber. This method allows for the direct measurement of the fission rate in the activation target with no reference to the fission cross-section, reducing uncertainties. γ-ray counting was performed on well-shield HPGe detectors over a period of 2 months per activation to properly identify fission products. Reported are absolute cumulative fission product yields for incident neutron energies of 0.5, 1.37, 2.4, 4.6 and 14.8 MeV.

  1. Communication: Energy-dependent resonance broadening in symmetric and asymmetric molecular junctions from an ab initio non-equilibrium Green's function approach

    NASA Astrophysics Data System (ADS)

    Liu, Zhen-Fei; Neaton, Jeffrey B.

    2014-10-01

    The electronic structure of organic-inorganic interfaces often features resonances originating from discrete molecular orbitals coupled to continuum lead states. An example is molecular junction, individual molecules bridging electrodes, where the shape and peak energy of such resonances dictate junction conductance, thermopower, I-V characteristics, and related transport properties. In molecular junctions where off-resonance coherent tunneling dominates transport, resonance peaks in the transmission function are often assumed to be Lorentzian functions with an energy-independent broadening parameter Γ. Here we define a new energy-dependent resonance broadening function, Γ(E), based on diagonalization of non-Hermitian matrices, which can describe resonances of a more complex, non-Lorentzian nature and can be decomposed into components associated with the left and right leads, respectively. We compute this quantity via an ab initio non-equilibrium Green's function (NEGF) approach based on density functional theory (DFT) for both symmetric and asymmetric molecular junctions, and show that our definition of Γ(E), when combined with Breit-Wigner formula, reproduces the transmission calculated from DFT-NEGF. Through a series of examples, we illustrate how this approach can shed new light on experiments and understanding of junction transport properties in terms of molecular orbitals.

  2. Energy-dependent, carrier-mediated extrusion of carboxyfluorescein from Saccharomyces cerevisiae allows rapid assessment of cell viability by flow cytometry.

    PubMed Central

    Breeuwer, P; Drocourt, J L; Rombouts, F M; Abee, T

    1994-01-01

    Carboxyfluorescein diacetate is a nonfluorescent compound which can be used in combination with flow cytometry for vital staining of yeasts and bacteria. The basis of this method is the assumption that, once inside the cell, carboxyfluorescein diacetate is hydrolyzed by nonspecific esterases to produce the fluorescent carboxyfluorescein (cF). cF is retained by cells with intact membranes (viable cells) and lost by cells with damaged membranes. In this report, we show that Saccharomyces cerevisiae extrudes cF in an energy-dependent manner. This efflux was studied in detail, and several indications that a transport system is involved were found. Efflux of cF was stimulated by the addition of glucose and displayed Michaelis-Menten kinetics. A Km for cF transport of 0.25 mM could be determined. The transport of cF was inhibited by the plasma membrane H(+)-ATPase inhibitors N,N'-dicyclohexylcarbodiimide and diethylstilbestrol and by high concentrations of tetraphenylphosphonium ions. These treatments resulted in a dissipation of the proton motive force, whereas the intracellular ATP concentration remained high. Transport of cF is therefore most probably driven by the membrane potential and/or the pH gradient. The viability of S. cerevisiae was determined by a two-step procedure consisting of loading the cells with cF followed by incubation at 40 degrees C in the presence of glucose. Subsequently, the fluorescence intensity of the cells was analyzed by flow cytometry. The efflux experiments showed an excellent correlation between the viability of S. cerevisiae cells and the ability to translocate cF. This method should prove of general utility for the rapid assessment of yeast vitality and viability. PMID:8017931

  3. GEOS 1 observations of low-energy ions in the earth's plasmasphere - A study on composition, and temperature and density structure under quiet geomagnetic conditions

    NASA Astrophysics Data System (ADS)

    Farrugia, C. J.; Geiss, J.; Balsiger, H.; Young, D. T.

    Data are presented on the composition and the temperature (T) and density (N) distributions of the earth's plasmasphere ionic population, obtained from GEOS 1 thermal-ion data. In deriving the N and T of the ions, a novel technique was employed, which is based on the modulation of the count rates by the spacecraft's spin. It was found that, for the major ion species H(+) and He(+), the relative density abundance He(+)/H(+) value of several percent was fairly common; the H(+) and He(+) ions are generally in thermal equilibrium, with temperatures varying between 4000 and 15,000 K, with a tendency to increase with L value. A comparison of the thermal structure obtained with those obtained by the Plasma Composition Experiment on ISEE and the Retarding Ion Mass Spectrometer on DE 1 showed no systematic difference between the 'energy' techniques used in these studies and the present 'angular' technique.

  4. Ion composition of the bulk ring current during a magnetic storm - Observations with the CHEM-instrument on AMPTE-CCE

    NASA Technical Reports Server (NTRS)

    Stuedemann, W.; Wilken, B.; Kremser, G.; Gloeckler, G.; Ipavich, F. M.

    1986-01-01

    Ion composition measurements in the entire energy range of the ring current population, obtained with the Charge-, Energy-, Mass-spectrometer instrument on the Charge Composition Explorer in September 1984, are reported. From the energy spectra obtained for all major constituents during the main phase of a magnetic storm, the number densities, energy densities, and mean energies are calculated and displayed as radial profiles. The mean energies of He(2+) are found to be about twice that of H(+) and He(+) throughout this storm, and the time profiles for the mean energies of all major ions are seen to bunch together (when normalizing mean energies by the ionic charge), with the largest variations of the energy densities and mean energies occurring for O(+) ions.

  5. Influence of phantom materials on the energy dependence of LiF:Mg,Ti thermoluminescent dosimeters exposed to 20-300 kV narrow x-ray spectra, 137Cs and 60Co photons.

    PubMed

    Massillon-J L, G; Cabrera-Santiago, A; Minniti, R; O'Brien, M; Soares, C G

    2014-08-07

    LiF:Mg,Ti, are widely used to estimate absorbed-dose received by patients during diagnostic or medical treatment. Conveniently, measurements are usually made in plastic phantoms. However, experimental conditions vary from one group to another and consequently, a lack of consensus data exists for the energy dependence of thermoluminescent (TL) response. This work investigated the energy dependence of TLD-100 TL-response and the effect of irradiating the dosimeters in different phantom materials for a broad range of energy photons in an attempt to understand the parameters that affect the discrepancies reported by various research groups. TLD-100s were exposed to 20-300 kV narrow x-ray spectra, (137)Cs and (60)Co photons. Measurements were performed in air, PMMA, wt1, polystyrene and TLDS as surrounding material. Total air-kerma values delivered were between 50 and 150 mGy for x-rays and 50 mGy for (137)Cs and (60)Co beams; each dosimeter was irradiated individually. Relative response, R, defined as the TL-response per air-kerma and relative efficiency, RE, described as the TL-response per absorbed-dose (obtained through Monte Carlo (MC) and analytically) were used to describe the TL-response. Both R and RE are normalized to the responses in a (60)Co beam. The results indicate that the use of different phantom materials affects the TL-response and this response varies with energy and material type. MC simulations reproduced qualitatively the experimental data: a) R increases, reaches a maximum at ~25 keV and decreases; b) RE decreases, down to a minimum at ~60 keV, increases to a maximum at ~150 keV and after decreases. Independent of the phantom materials, RE strongly depends on how the absorbed dose is evaluated and the discrepancies between RE evaluated analytically and by MC simulation are around 4% and 18%, dependent on the photon energy. The comparison between our results and that reported in the literature suggests that the discrepancy observed

  6. Determination of the intrinsic energy dependence of LiF:Mg,Ti thermoluminescent dosimeters for {sup 125}I and {sup 103}Pd brachytherapy sources relative to {sup 60}Co

    SciTech Connect

    Reed, J. L. Micka, J. A.; Culberson, W. S.; DeWerd, L. A.; Rasmussen, B. E.; Davis, S. D.

    2014-12-15

    Purpose: To determine the intrinsic energy dependence of LiF:Mg,Ti thermoluminescent dosimeters (TLD-100) for {sup 125}I and {sup 103}Pd brachytherapy sources relative to {sup 60}Co. Methods: LiF:Mg,Ti TLDs were irradiated with low-energy brachytherapy sources and with a {sup 60}Co teletherapy source. The brachytherapy sources measured were the Best 2301 {sup 125}I seed, the OncoSeed 6711 {sup 125}I seed, and the Best 2335 {sup 103}Pd seed. The TLD light output per measured air-kerma strength was determined for the brachytherapy source irradiations, and the TLD light output per air kerma was determined for the {sup 60}Co irradiations. Monte Carlo (MC) simulations were used to calculate the dose-to-TLD rate per air-kerma strength for the brachytherapy source irradiations and the dose to TLD per air kerma for the {sup 60}Co irradiations. The measured and MC-calculated results for all irradiations were used to determine the TLD intrinsic energy dependence for {sup 125}I and {sup 103}Pd relative to {sup 60}Co. Results: The relative TLD intrinsic energy dependences (relative to {sup 60}Co) and associated uncertainties (k = 1) were determined to be 0.883 ± 1.3%, 0.870 ± 1.4%, and 0.871 ± 1.5% for the Best 2301 seed, OncoSeed 6711 seed, and Best 2335 seed, respectively. Conclusions: The intrinsic energy dependence of TLD-100 is dependent on photon energy, exhibiting changes of 13%–15% for {sup 125}I and {sup 103}Pd sources relative to {sup 60}Co. TLD measurements of absolute dose around {sup 125}I and {sup 103}Pd brachytherapy sources should explicitly account for the relative TLD intrinsic energy dependence in order to improve dosimetric accuracy.

  7. Changes in the Cytoplasmic Composition of Amino Acids and Proteins Observed in Staphylococcus aureus during Growth under Variable Growth Conditions Representative of the Human Wound Site

    PubMed Central

    Alreshidi, Mousa M.; Dunstan, R. Hugh; Gottfries, Johan; Macdonald, Margaret M.; Crompton, Marcus J.; Ang, Ching-Seng; Williamson, Nicholas A.; Roberts, Tim K.

    2016-01-01

    Staphylococcus aureus is an opportunistic pathogen responsible for a high proportion of nosocomial infections. This study was conducted to assess the bacterial responses in the cytoplasmic composition of amino acids and ribosomal proteins under various environmental conditions designed to mimic those on the human skin or within a wound site: pH6-8, temperature 35–37°C, and additional 0–5% NaCl. It was found that each set of environmental conditions elicited substantial adjustments in cytoplasmic levels of glutamic acid, aspartic acid, proline, alanine and glycine (P< 0.05). These alterations generated characteristic amino acid profiles assessed by principle component analysis (PCA). Substantial alterations in cytoplasmic amino acid and protein composition occurred during growth under conditions of higher salinity stress implemented via additional levels of NaCl in the growth medium. The cells responded to additional NaCl at pH 6 by reducing levels of ribosomal proteins, whereas at pH 8 there was an upregulation of ribosomal proteins compared with the reference control. The levels of two ribosomal proteins, L32 and S19, remained constant across all experimental conditions. The data supported the hypothesis that the bacterium was continually responding to the dynamic environment by modifying the proteome and optimising metabolic homeostasis. PMID:27442022

  8. Observations and Modeling of Composition of Upper Troposphere/Lower Stratosphere (UTILS): Isentropic Mixing Events and Morphology of HNO3 as Observed by HIRDLS and Comparison with Results from Global Modeling Initiative

    NASA Technical Reports Server (NTRS)

    Rodriquez, J. M.; Douglass, A.R.; Yoshida, Y.; Strahan, S.; Duncan, B.; Olsen, M.; Gille, J.; Yudin, V.; Nardi, B.

    2008-01-01

    isentropic exchange of air masses between the tropical upper troposphere and mid-latitude lowermost stratosphere (the so-called "middle world") is an important pathway for stratospheric-tropospheric exchange. A seasonal, global view of this process has been difficult to obtain, in part due to the lack of the vertical resolution in satellite observations needed to capture the laminar character of these events. Ozone observations at a resolution of about 1 km from the High Resolution Dynamic Limb Sounder (HIRDLS) on NASA's Aura satellite show instances of these intrusions. Such intrusions should also be observable in HN03 observations; however, the abundances of nitric acid could be additionally controlled by chemical processes or incorporation and removal into ice clouds. We present a systematic examination of the HIRDLS data on O3 and HNO3 to determine the seasonal and spatial characteristics of the distribution of isentropic intrusions. At the same time, we compare the observed distributions with those calculated by the Global Modeling Initiative combined tropospheric-stratospheric model, which has a vertical resolution of about I km. This Chemical Transport Model (CTM) is driven by meteorological fields obtained from the GEOS-4 system of NASA/Goddard Global Modeling and Assimilation Office (GMAO), for the Aura time period, at a vertical resolution of about 1 km. Such comparison brings out the successes and limitations of the model in representing isentropic stratospheric-tropospheric exchange, and the different processes controlling HNO3 in the UTAS.

  9. SU-F-19A-06: Experimental Investigation of the Energy Dependence of TLD Sensitivity in Low-Energy Photon Beams

    SciTech Connect

    Chen, Z; Nath, R

    2014-06-15

    Purpose: To measure the energy dependence of TLD sensitivity in lowenergy photon beams with equivalent mono-energetic energy matching those of 103Pd, 125I and 131Cs brachytherapy sources. Methods: A Pantek DXT 300 x-ray unit (Precision X-ray, Branford, CT), with stable digital voltage control down to 20 kV, was used to establish three lowenergy photon beams with narrow energy spread and equivalent monoenergetic energies matching those of 103Pd, 125I and 131Cs brachytherapy sources. The low-energy x-ray beams and a reference 6 MV photon beam were calibrated according to the AAPM TG-61 and TG-51 protocols, respectively, using a parallel-plate low-energy chamber and a Farmer cylindrical chamber with NIST traceable calibration factors. The dose response of model TLD-100 micro-cubes (1×1×1 mm{sup 3}) in each beam was measured for five different batches of TLDs (each contained approximately 100 TLDs) that have different histories of irradiation and usage. Relative absorbed dose sensitivity was determined as the quotient of the slope of dose response for a beam-of-interest to that of the reference beam. Results: Equivalent mono-energetic photon energies of the low-energy beams established for 103Pd, 125I and 131Cs sources were 20.5, 27.5, and 30.1 keV, respectively. Each beam exhibited narrow spectral spread with energyhomogeneity index close to 90%. The relative absorbed-dose sensitivity was found to vary between different batches of TLD with maximum differences of up to 8%. The mean and standard deviation determined from the five TLD batches was 1.453 ± 0.026, 1.541 ± 0.035 and 1.529 ± 0.051 for the simulated 103P, 125I and 131Cs beams, respectively. Conclusion: Our measured relative absorbed-dose sensitivities are greater than the historically measured value of 1.41. We find that the relative absorbed-dose sensitivity of TLD in the 103P beam is approximately 5% lower than that of 125I and 131Cs beams. Comparison of our results with other studies will be presented.

  10. Submillimeter Observation of Jupiter’s Stratospheric Composition: Detection of Carbon Monosulfide (J=7-6) 19 Years After the Cometary Impact

    NASA Astrophysics Data System (ADS)

    Iino, T.; Ohyama, H.; Hirahara, Y.; Takahashi, T.; Tsukagoshi, T.

    2016-12-01

    In Jupiter's stratosphere, gaseous carbon monosulfide (CS) was first discovered in 1994 by millimeter and ultraviolet observations as a product induced by the collision of comet Shoemaker-Levy 9 (SL9). To constrain sulfur chemistry, in 2013, 19 years after the SL9 event, we observed Jupiter's stratospheric CS J = 7 - 6 rotational transition at 0.8 mm wavelength by using the Atacama Submillimeter Telescope Experiment 10 m single-dish telescope. The CS molecular line was successfully detected with 120 mK intensity in the antenna temperature scale. The obtained CS total mass shows ˜90% decrease relative to that observed in 1998. From the line shape analysis, CS is suggested to be present above the {0.2}-0.15+0.4 mbar pressure level, which is comparable to that determined in 1998.

  11. HST-COS OBSERVATIONS OF AGNs. III. SPECTRAL CONSTRAINTS IN THE LYMAN CONTINUUM FROM COMPOSITE COS/G140L DATA

    SciTech Connect

    Tilton, Evan M.; Shull, J. Michael; Danforth, Charles W.; Stevans, Matthew L. E-mail: michael.shull@colorado.edu E-mail: stevans@astro.as.utexas.edu

    2016-01-20

    The rest-frame ultraviolet (UV) spectra of active galactic nuclei (AGNs) are important diagnostics of both accretion disk physics and their contribution to the metagalactic ionizing UV background. Though the mean AGN spectrum is well characterized with composite spectra at wavelengths greater than 912 Å, the shorter-wavelength extreme-UV (EUV) remains poorly studied. In this third paper in a series on the spectra of AGNs, we combine 11 new spectra taken with the Cosmic Origins Spectrograph on the Hubble Space Telescope with archival spectra to characterize the typical EUV spectral slope of AGNs from λ{sub rest} ∼ 850 Å down to λ{sub rest} ∼ 425 Å. Parameterizing this slope as a power law, we obtain F{sub ν} ∝ ν{sup −0.72±0.26}, but we also discuss the limitations and systematic uncertainties of this model. We identify broad emission features in this spectral region, including emission due to ions of O, Ne, Mg, and other species, and we limit the intrinsic He i 504 Å photoelectric absorption edge opacity to τ{sub He} {sub i} < 0.047.

  12. In-Flight Chemical Composition Observations of Aircraft Emissions using a High-Resolution Time-of-Flight Aerosol Mass Spectrometer

    NASA Astrophysics Data System (ADS)

    Ziemba, L. D.; Martin, R.; Moore, R.; Shook, M.; Thornhill, K. L., II; Winstead, E.; Anderson, B. E.

    2015-12-01

    Commercial aircraft are an important source of aerosols to the upper troposphere. The microphysical and chemical properties of these emitted aerosols govern their ability to act as ice nuclei, both in near-field contrails and for cirrus formation downstream. During the ACCESS-II (Alternative Fuel Effects on Contrails and Cruise Emissions) campaign, NASA DC-8 CFM56-2-C1 engine emissions were sampled systematically at a range of cruise-relevant thrust levels and at several altitudes. Sampling was done aboard the NASA HU-25 Falcon aircraft, which was equipped with a suite of aerosol and gas-phase instruments focused on assessing the effects of burning different fuel mixtures on aerosol properties and their associated contrails. Here we present in-flight measurements of particle chemical composition made by a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS). The AMS was able to sufficiently resolve near-field (within 100m) aircraft emissions plumes. Low-sulfur HEFA (hydro-processed esters and fatty-acids) and JetA fuels yielded particles that contained 11 and 8% sulfate, respectively, compared to 30% sulfate contribution for traditional JetA fuel. Each of the fuels produced organic aerosol with similarly low oxygen content. Lubrication oils, which are not a combustion product but result from leaks in the engine, were likely a dominant fraction of the measured organic mass based on mass-spectral marker analysis. These results are compared to similar engine conditions from ground-based testing.

  13. Modern Observational Techniques for Comets

    NASA Technical Reports Server (NTRS)

    Brandt, J. C. (Editor); Greenberg, J. M. (Editor); Donn, B. (Editor); Rahe, J. (Editor)

    1981-01-01

    Techniques are discussed in the following areas: astrometry, photometry, infrared observations, radio observations, spectroscopy, imaging of coma and tail, image processing of observation. The determination of the chemical composition and physical structure of comets is highlighted.

  14. In situ vertical profiles of aerosol extinction, mass, and composition over the southeast United States during SENEX and SEAC4RS: observations of a modest aerosol enhancement aloft

    NASA Astrophysics Data System (ADS)

    Wagner, N. L.; Brock, C. A.; Angevine, W. M.; Beyersdorf, A.; Campuzano-Jost, P.; Day, D. A.; de Gouw, J. A.; Diskin, G. S.; Gordon, T. D.; Graus, M. G.; Huey, G.; Jimenez, J. L.; Lack, D. A.; Liao, J.; Liu, X.; Markovic, M. Z.; Middlebrook, A. M.; Mikoviny, T.; Peischl, J.; Perring, A. E.; Richardson, M. S.; Ryerson, T. B.; Schwarz, J. P.; Warneke, C.; Welti, A.; Wisthaler, A.; Ziemba, L. D.; Murphy, D. M.

    2015-02-01

    Vertical profiles of submicron aerosol over the southeastern United States (SEUS) during the summertime from in situ aircraft-based measurements were used to construct aggregate profiles of chemical, microphysical, and optical properties. Shallow cumulus convection was observed during many profiles. These conditions enhance vertical transport of trace gases and aerosol and create a cloudy transition layer on top of the sub-cloud mixed layer. The trace gas and aerosol concentrations in the transition layer were modeled as a mixture with contributions from the mixed layer below and the free troposphere above. The amount of vertical mixing, or entrainment of air from the free troposphere, was quantified using the observed mixing ratio of carbon monoxide (CO). Although the median aerosol mass, extinction, and volume decreased with altitude in the transition layer, they were ~10% larger than expected from vertical mixing alone. This enhancement was likely due to secondary aerosol formation in the transition layer. Although the transition layer enhancements of the particulate sulfate and organic aerosol (OA) were both similar in magnitude, only the enhancement of sulfate was statistically significant. The column integrated extinction, or aerosol optical depth (AOD), was calculated for each individual profile, and the transition layer enhancement of extinction typically contributed less than 10% to the total AOD. Our measurements and analysis were motivated by two recent studies that have hypothesized an enhanced layer of secondary organic aerosol (SOA) aloft to explain the summertime enhancement of AOD (2-3 times greater than winter) over the southeastern United States. In contrast to this hypothesis, the modest enhancement we observed in the transition layer was not dominated by OA and was not a large fraction of the summertime AOD.

  15. Satellite and Ground-Based Observations of Auroral Energy Deposition and the Effects on Thermospheric Composition During Large Geomagnetic Storms: 1. Great Geomagnetic Storm of 20 November 2003

    DTIC Science & Technology

    2008-01-01

    energy electrons based sites such as at Poker Flat , Alaska and Kangerlus- or other differences in the energy distribution during the suaq, Greenland...and riometer observations from the Alaska chain in Poker ship is linear or of higher order [Hecht et al., 2006]. Flat and Fort Yukon, photometric...Coordinates of Ground-Based Locations Site Geographic Lat Geographic Long Geomagnetic Lat Geomagnetic Long Fort Yukon 66.6 214.7 67.3 -94.7 Poker Flat 65.1

  16. Static versus energy-dependent nucleus-nucleus potential for description of sub-barrier fusion dynamics of {}_{8}^{16}O+{}^{112,116,120}\\!\\!\\!\\!\\!\\!{}_{50}Sn reactions

    NASA Astrophysics Data System (ADS)

    Manjeet Singh, Gautam

    2015-11-01

    The static and energy-dependent nucleus-nucleus potentials are simultaneously used along with the Wong formula for exploration of fusion dynamics of {}816O+{}112,116,120{}50Sn reactions. The role of internal structure degrees of freedom of colliding pairs, such as inelastic surface vibrations, are examined within the context of coupled channel calculations performed using the code CCFULL. Theoretical calculations based on the static Woods-Saxon potential along with the one-dimensional Wong formula fail to address the fusion data of {}816O+{}112,116,120{}50Sn reactions. Such discrepancies can be removed if one uses couplings to internal structure degrees of freedom of colliding nuclei. However, the energy-dependent Woods-Saxon potential model (EDWSP model) accurately describes the sub-barrier fusion enhancement of {}816O+{}112,116,120{}50Sn reactions. Therefore, in sub-barrier fusion dynamics, energy dependence in the nucleus-nucleus potential governs barrier modification effects in a closely similar way to that of the coupled channel approach. Supported by Dr. D. S. Kothari Post-Doctoral Fellowship Scheme sponsored by University Grants Commission (UGC), New Delhi, India

  17. Aircraft Observations of Aerosol Composition and Ageing in New England and Mid-Atlantic States during the Summer 2002 New England Air Quality Study Field Campaign

    SciTech Connect

    Kleinman, Lawrence I.; Daum, Peter H.; Lee, Y.- N.; Senum, Gunar; Springston, Stephen R.; Wang, Jian; Berkowitz, Carl M.; Hubbe, John M.; Zaveri, Rahul A.; Brechtel, Fred J.; Jayne, J. T.; Onasch, Timothy B.; Worsnop, Douglas R.

    2007-05-11

    Aerosol chemical composition, size distributions, and optical properties were measured during 17 aircraft flights in New England and Middle Atlantic States as part of the summer 2002 NEAQS field campaign. An Aerodyne Aerosol Mass Spectrometer (AMS) was operated with a measurement cycle of 30 s, about an order of magnitude faster than used for ground-based measurements. Noise levels within a single measurement period were sub μg m-3. Volume data derived from the AMS were compared with volume measurements from a PCASP optical particle detector and an Scanning Mobility Particle Spectrometer (SMPS); calculated light scattering was compared with measured values from an integrating nephelometer. The median ratio for AMS/SMPS volume was 1.25; the median ratio for AMS/nephelometer scattering was 1.18. Size spectra were compared for subsets of samples with different effective diameters (Deff). There is good agreement between the AMS, PCASP, and SMPS spectra for larger values of Deff but an unexplained over-prediction in the AMS for small values. A dependence of the AMS collection efficiency on aerosol acidity was quantified by a comparison between AMS and PCASP volumes in 2 high sulfate plumes. Average aerosol concentrations were 11 μg m-3. The organic content was high in comparison to monitoring data from the IMPROVE network, varying from 70% in clean air to 40% in high concentration sulfate plumes. The ratio of organic aerosol to CO and light absorption acting were examined as a function of photochemical age. CO is a conservative tracer for urban emissions and light absorption is a surrogate for black carbon which is also conservative. Comparisons were made to surface ratios measured under conditions where there is little secondary organic aerosol (SOA). An increase in these ratios relative to surface values indicates that 70 - 80% of the organic aerosol in polluted air masses was secondary. Most of this SOA is rapidly formed within a few hours. At longer time scales

  18. UV observations of the cool DBQA5 white dwarf LDS 678A - Limits on the atmospheric composition, pressure shift, and gravitational redshift derived from C I 2479

    NASA Technical Reports Server (NTRS)

    Oswalt, Terry D.; Sion, Edward M.; Hammond, Gordon; Vauclair, Gerard; Liebert, James W.

    1991-01-01

    A high-resolution ultraviolet spectrum of the helium-rich degenerate LDS 678A, obtained with the International Ultraviolet Explorer (IUE) satellite, is presented. LDS 678A is the coolest metallic line degenerate (DQ or DZ) yet observed with the IUE echelle. These observations provide a detailed line profile of the strong C I 2479 absorption line and equivalent width W2479 = 2.35 + or - 0.06 A from which theoretical profile fits yield a carbon abundance of log C/He = (-6.7 + or- 0.2). The presence of carbon in a He-rich atmosphere lends credence to the notion that LDS 678A is a transitional case between the DB white dwarfs with nearly pure helium atmospheres and the helium-rich DQ white dwarfs which exhibit carbon bands. Corrected for an inferred pressure shift Vp = + 38 + or - 4 km/s for the C I 2479 line, a gravitational redshift of Vrs = + 26 + or - 13 km/s is deduced from which a most probable mass of 0.55 solar mass is derived.

  19. The study of seasonal composition and dynamics of wetland ecosystems and wintering bird habitat at Poyang Lake, PR China using object-based image analysis and field observations

    NASA Astrophysics Data System (ADS)

    Dronova, Iryna

    Wetlands are among the most productive ecosystems in the world which support critical ecological services and high biological diversity yet are vulnerable to climate change and human activities. In this thesis, I investigated the capabilities of satellite remote sensing with medium spatial resolution and object-based image analysis (OBIA) methods to elucidate seasonal composition and dynamics of wetland ecosystems and indicators of habitat for wintering waterbirds in a large conservation hotspot of Poyang Lake, PR China. I first examined changes in major wetland cover types during the low water period when Poyang Lake provides habitat to large numbers of migratory birds from the East Asian pathway. I used OBIA to map and analyze the transitions among water, vegetation, mudflat and sand classes from four 32-m Beijing-1 microsatellite images between late fall 2007 and early spring 2008. This analysis revealed that, while transitions among wetland classes were strongly associated with precipitation and flood-driven hydrological variation, the overall dynamics were a more complex interplay of vegetation phenology, disturbance and post-flood exposure. Remote sensing signals of environmental processes were more effectively captured by changes in fuzzy memberships to each class per location than by changes in spatial extents of the best-matching classes alone. The highest uncertainty in the image analysis corresponded to transitional wetland states at the end of the major flood recession in November and to heterogeneous mudflat areas at the land-water interface during the whole study period. Results suggest seasonally exposed mudflat features as important targets for future research due to heterogeneity and uncertainty of their composition, variable spatial distribution and sensitivity to hydrological dynamics. I further explored the potential of OBIA to overcome the limitations of the traditional pixel-based image classification methods in characterizing Poyang Lake

  20. Keck and VLT Observations of Super-Damped Lyman-Alpha Absorbers at z 2- 2.5: Constraints on Chemical Compositions and Physical Conditions

    NASA Astrophysics Data System (ADS)

    Kulkarni, Varsha P.; Som, Debopam; Morrison, Sean; Péroux, Celine; Quiret, Samuel; York, Donald G.

    2015-12-01

    We report Keck/Echellette Spectrograph and Imager and Very Large Telescope/Ultraviolet-Visual Echelle Spectrograph observations of three super-damped Lyα quasar absorbers with H i column densities log NH i ≥ 21.7 at redshifts 2 ≲ z ≲ 2.5. All three absorbers show similar metallicities (˜-1.3 to -1.5 dex), and dust depletion of Fe, Ni, and Mn. Two of the absorbers show supersolar [S/Zn] and [Si/Zn]. We combine our results with those for other damped Lyα a absorbers (DLAs) to examine trends between NH i, metallicity, and dust depletion. A larger fraction of the super-DLAs lie close to or above the line [X/H] = 20.59 - log NH i in the metallicity versus NH i plot, compared to the less gas-rich DLAs, suggesting that super-DLAs are more likely to be rich in molecules. Unfortunately, our data for Q0230-0334 and Q0743+1421 do not cover H2 absorption lines. For Q1418+0718, some H2 lines are covered, but not detected. CO is not detected in any of our absorbers. For DLAs with log NH i < 21.7, we confirm strong correlation between metallicity and Fe depletion, and find a correlation between metallicity and Si depletion. For super-DLAs, these correlations are weaker or absent. The absorbers toward Q0230-0334 and Q1418+0718 show potential detections of weak Lyα emission, implying star formation rates of ˜1.6 and ˜0.7 M⊙ yr-1, respectively (ignoring dust extinction). Upper limits on the electron densities from C ii*/C ii or Si ii*/Si ii are low, but are higher than the median values in less gas-rich DLAs. Finally, systems with log NH i > 21.7 may have somewhat narrower velocity dispersions Δv90 than the less gas-rich DLAs, and may arise in cooler and/or less turbulent gas. Includes observations collected during program ESO 93.A-0422 at the European Southern Observatory (ESO) Very Large Telescope (VLT) with the Ultraviolet-Visual Echelle Spectrograph (UVES) on the 8.2 m telescopes operated at the Paranal Observatory, Chile. Some of the data presented herein were

  1. Depth of maximum of air-shower profiles at the Pierre Auger Observatory. II. Composition implications

    NASA Astrophysics Data System (ADS)

    Aab, A.; Abreu, P.; Aglietta, M.; Ahn, E. J.; Al Samarai, I.; Albuquerque, I. F. M.; Allekotte, I.; Allen, J.; Allison, P.; Almela, A.; Alvarez Castillo, J.; Alvarez-Muñiz, J.; Alves Batista, R.; Ambrosio, M.; Aminaei, A.; Anchordoqui, L.; Andringa, S.; Aramo, C.; Aranda, V. M.; Arqueros, F.; Asorey, H.; Assis, P.; Aublin, J.; Ave, M.; Avenier, M.; Avila, G.; Awal, N.; Badescu, A. M.; Barber, K. B.; Bäuml, J.; Baus, C.; Beatty, J. J.; Becker, K. H.; Bellido, J. A.; Berat, C.; Bertania, M. E.; Bertou, X.; Biermann, P. L.; Billoir, P.; Blaess, S.; Blanco, M.; Bleve, C.; Blümer, H.; Boháčová, M.; Boncioli, D.; Bonifazi, C.; Bonino, R.; Borodai, N.; Brack, J.; Brancus, I.; Bridgeman, A.; Brogueira, P.; Brown, W. C.; Buchholz, P.; Bueno, A.; Buitink, S.; Buscemi, M.; Caballero-Mora, K. S.; Caccianiga, B.; Caccianiga, L.; Candusso, M.; Caramete, L.; Caruso, R.; Castellina, A.; Cataldi, G.; Cazon, L.; Cester, R.; Chavez, A. G.; Chiavassa, A.; Chinellato, J. A.; Chudoba, J.; Cilmo, M.; Clay, R. W.; Cocciolo, G.; Colalillo, R.; Coleman, A.; Collica, L.; Coluccia, M. R.; Conceição, R.; Contreras, F.; Cooper, M. J.; Cordier, A.; Coutu, S.; Covault, C. E.; Cronin, J.; Curutiu, A.; Dallier, R.; Daniel, B.; Dasso, S.; Daumiller, K.; Dawson, B. R.; de Almeida, R. M.; De Domenico, M.; de Jong, S. J.; de Mello Neto, J. R. T.; De Mitri, I.; de Oliveira, J.; de Souza, V.; del Peral, L.; Deligny, O.; Dembinski, H.; Dhital, N.; Di Giulio, C.; Di Matteo, A.; Diaz, J. C.; Díaz Castro, M. L.; Diogo, F.; Dobrigkeit, C.; Docters, W.; D'Olivo, J. C.; Dorofeev, A.; Dorosti Hasankiadeh, Q.; Dova, M. T.; Ebr, J.; Engel, R.; Erdmann, M.; Erfani, M.; Escobar, C. O.; Espadanal, J.; Etchegoyen, A.; Facal San Luis, P.; Falcke, H.; Fang, K.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Ferguson, A. P.; Fernandes, M.; Fick, B.; Figueira, J. M.; Filevich, A.; Filipčič, A.; Fox, B. D.; Fratu, O.; Fröhlich, U.; Fuchs, B.; Fuji, T.; Gaior, R.; García, B.; Garcia Roca, S. T.; Garcia-Gamez, D.; Garcia-Pinto, D.; Garilli, G.; Gascon Bravo, A.; Gate, F.; Gemmeke, H.; Ghia, P. L.; Giaccari, U.; Giammarchi, M.; Giller, M.; Glaser, C.; Glass, H.; Gómez Berisso, M.; Gómez Vitale, P. F.; Gonçalves, P.; Gonzalez, J. G.; González, N.; Gookin, B.; Gordon, J.; Gorgi, A.; Gorham, P.; Gouffon, P.; Grebe, S.; Griffith, N.; Grillo, A. F.; Grubb, T. D.; Guarino, F.; Guedes, G. P.; Hampel, M. R.; Hansen, P.; Harari, D.; Harrison, T. A.; Hartmann, S.; Harton, J. L.; Haungs, A.; Hebbeker, T.; Heck, D.; Heimann, P.; Herve, A. E.; Hill, G. C.; Hojvat, C.; Hollon, N.; Holt, E.; Homola, P.; Hörandel, J. R.; Horvath, P.; Hrabovský, M.; Huber, D.; Huege, T.; Insolia, A.; Isar, P. G.; Jandt, I.; Jansen, S.; Jarne, C.; Josebachuili, M.; Kääpä, A.; Kambeitz, O.; Kampert, K. H.; Kasper, P.; Katkov, I.; Kégl, B.; Keilhauer, B.; Keivani, A.; Kemp, E.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Krause, R.; Krohm, N.; Krömer, O.; Kruppke-Hansen, D.; Kuempel, D.; Kunka, N.; LaHurd, D.; Latronico, L.; Lauer, R.; Lauscher, M.; Lautridou, P.; Le Coz, S.; Leão, M. S. A. B.; Lebrun, D.; Lebrun, P.; Leigui de Oliveira, M. A.; Letessier-Selvon, A.; Lhenry-Yvon, I.; Link, K.; López, R.; Lopez Agüera, A.; Louedec, K.; Lozano Bahilo, J.; Lu, L.; Lucero, A.; Ludwig, M.; Malacari, M.; Maldera, S.; Mallamaci, M.; Maller, J.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Marin, V.; Mariş, I. C.; Marsella, G.; Martello, D.; Martin, L.; Martinez, H.; Martínez Bravo, O.; Martraire, D.; Masías Meza, J. J.; Mathes, H. J.; Mathys, S.; Matthews, J.; Matthews, J. A. J.; Matthiae, G.; Maurel, D.; Maurizio, D.; Mayotte, E.; Mazur, P. O.; Medina, C.; Medina-Tanco, G.; Meissner, R.; Melissas, M.; Melo, D.; Menshikov, A.; Messina, S.; Meyhandan, R.; Mićanović, S.; Micheletti, M. I.; Middendorf, L.; Minaya, I. A.; Miramonti, L.; Mitrica, B.; Molina-Bueno, L.; Mollerach, S.; Monasor, M.; Monnier Ragaigne, D.; Montanet, F.; Morello, C.; Mostafá, M.; Moura, C. A.; Muller, M. A.; Müller, G.; Müller, S.; Münchmeyer, M.; Mussa, R.; Navarra, G.; Navas, S.; Necesal, P.; Nellen, L.; Nelles, A.; Neuser, J.; Nguyen, P.; Niechciol, M.; Niemietz, L.; Niggemann, T.; Nitz, D.; Nosek, D.; Novotny, V.; Nožka, L.; Ochilo, L.; Olinto, A.; Oliveira, M.; Pacheco, N.; Pakk Selmi-Dei, D.; Palatka, M.; Pallotta, J.; Palmieri, N.; Papenbreer, P.; Parente, G.; Parra, A.; Paul, T.; Pech, M.; PÈ©kala, J.; Pelayo, R.; Pepe, I. M.; Perrone, L.; Petermann, E.; Peters, C.; Petrera, S.; Petrov, Y.; Phuntsok, J.; Piegaia, R.; Pierog, T.; Pieroni, P.; Pimenta, M.; Pirronello, V.; Platino, M.; Plum, M.; Porcelli, A.; Porowski, C.; Prado, R. R.; Privitera, P.; Prouza, M.; Purrello, V.; Quel, E. J.; Querchfeld, S.; Quinn, S.; Rautenberg, J.; Ravel, O.; Ravignani, D.; Revenu, B.; Ridky, J.; Riggi, S.; Risse, M.; Ristori, P.; Rizi, V.; Rodrigues de Carvalho, W.; Rodriguez Cabo, I.; Rodriguez Fernandez, G.; Rodriguez Rojo, J.; Rodríguez-Frías, M. D.; Rogozin, D.; Ros, G.; Rosado, J.; Rossler, T.; Roth, M.; Roulet, E.; Rovero, A. C.; Saffi, S. J.; Saftoiu, A.; Salamida, F.; Salazar, H.; Saleh, A.; Salesa Greus, F.; Salina, G.; Sánchez, F.; Sanchez-Lucas, P.; Santo, C. E.; Santos, E.; Santos, E. M.; Sarazin, F.; Sarkar, B.; Sarmento, R.; Sato, R.; Scharf, N.; Scherini, V.; Schieler, H.; Schiffer, P.; Schmidt, D.; Scholten, O.; Schoorlemmer, H.; Schovánek, P.; Schulz, A.; Schulz, J.; Schumacher, J.; Sciutto, S. J.; Segreto, A.; Settimo, M.; Shadkam, A.; Shellard, R. C.; Sidelnik, I.; Sigl, G.; Sima, O.; Śmiałkowski, A.; Šmída, R.; Snow, G. R.; Sommers, P.; Sorokin, J.; Squartini, R.; Srivastava, Y. N.; Stanič, S.; Stapleton, J.; Stasielak, J.; Stephan, M.; Stutz, A.; Suarez, F.; Suomijärvi, T.; Supanitsky, A. D.; Sutherland, M. S.; Swain, J.; Szadkowski, Z.; Szuba, M.; Taborda, O. A.; Tapia, A.; Tartare, M.; Tepe, A.; Theodoro, V. M.; Timmermans, C.; Todero Peixoto, C. J.; Toma, G.; Tomankova, L.; Tomé, B.; Tonachini, A.; Torralba Elipe, G.; Torres Machado, D.; Travnicek, P.; Trovato, E.; Tueros, M.; Ulrich, R.; Unger, M.; Urban, M.; Valdés Galicia, J. F.; Valiño, I.; Valore, L.; van Aar, G.; van Bodegom, P.; van den Berg, A. M.; van Velzen, S.; van Vliet, A.; Varela, E.; Vargas Cárdenas, B.; Varner, G.; Vázquez, J. R.; Vázquez, R. A.; Veberič, D.; Verzi, V.; Vicha, J.; Videla, M.; Villaseñor, L.; Vlcek, B.; Vorobiov, S.; Wahlberg, H.; Wainberg, O.; Walz, D.; Watson, A. A.; Weber, M.; Weidenhaupt, K.; Weindl, A.; Werner, F.; Widom, A.; Wiencke, L.; Wilczyńska, B.; Wilczyński, H.; Will, M.; Williams, C.; Winchen, T.; Wittkowski, D.; Wundheiler, B.; Wykes, S.; Yamamoto, T.; Yapici, T.; Yuan, G.; Yushkov, A.; Zamorano, B.; Zas, E.; Zavrtanik, D.; Zavrtanik, M.; Zaw, I.; Zepeda, A.; Zhou, J.; Zhu, Y.; Zimbres Silva, M.; Ziolkowski, M.; Zuccarello, F.; Pierre Auger Collaboration*

    2014-12-01

    Using the data taken at the Pierre Auger Observatory between December 2004 and December 2012, we have examined the implications of the distributions of depths of atmospheric shower maximum (Xmax ), using a hybrid technique, for composition and hadronic interaction models. We do this by fitting the distributions with predictions from a variety of hadronic interaction models for variations in the composition of the primary cosmic rays and examining the quality of the fit. Regardless of what interaction model is assumed, we find that our data are not well described by a mix of protons and iron nuclei over most of the energy range. Acceptable fits can be obtained when intermediate masses are included, and when this is done consistent results for the proton and iron-nuclei contributions can be found using the available models. We observe a strong energy dependence of the resulting proton fractions, and find no support from any of the models for a significant contribution from iron nuclei. However, we also observe a significant disagreement between the models with respect to the relative contributions of the intermediate components.

  2. Depth of maximum of air-shower profiles at the Pierre Auger Observatory. II. Composition implications

    SciTech Connect

    Aab, A.; Abreu, P.; Aglietta, M.; Ahn, E. J.; Al Samarai, I.; Albuquerque, I. F. M.; Allekotte, I.; Allen, J.; Allison, P.; Almela, A.; Alvarez Castillo, J.; Alvarez-Muñiz, J.; Alves Batista, R.; Ambrosio, M.; Aminaei, A.; Anchordoqui, L.; Andringa, S.; Aramo, C.; Aranda, V. M.; Arqueros, F.; Asorey, H.; Assis, P.; Aublin, J.; Ave, M.; Avenier, M.; Avila, G.; Awal, N.; Badescu, A. M.; Barber, K. B.; Bäuml, J.; Baus, C.; Beatty, J. J.; Becker, K. H.; Bellido, J. A.; Berat, C.; Bertania, M. E.; Bertou, X.; Biermann, P. L.; Billoir, P.; Blaess, S.; Blanco, M.; Bleve, C.; Blümer, H.; Boháčová, M.; Boncioli, D.; Bonifazi, C.; Bonino, R.; Borodai, N.; Brack, J.; Brancus, I.; Bridgeman, A.; Brogueira, P.; Brown, W. C.; Buchholz, P.; Bueno, A.; Buitink, S.; Buscemi, M.; Caballero-Mora, K. S.; Caccianiga, B.; Caccianiga, L.; Candusso, M.; Caramete, L.; Caruso, R.; Castellina, A.; Cataldi, G.; Cazon, L.; Cester, R.; Chavez, A. G.; Chiavassa, A.; Chinellato, J. A.; Chudoba, J.; Cilmo, M.; Clay, R. W.; Cocciolo, G.; Colalillo, R.; Coleman, A.; Collica, L.; Coluccia, M. R.; Conceição, R.; Contreras, F.; Cooper, M. J.; Cordier, A.; Coutu, S.; Covault, C. E.; Cronin, J.; Curutiu, A.; Dallier, R.; Daniel, B.; Dasso, S.; Daumiller, K.; Dawson, B. R.; de Almeida, R. M.; De Domenico, M.; de Jong, S. J.; de Mello Neto, J. R. T.; De Mitri, I.; de Oliveira, J.; de Souza, V.; del Peral, L.; Deligny, O.; Dembinski, H.; Dhital, N.; Di Giulio, C.; Di Matteo, A.; Diaz, J. C.; Díaz Castro, M. L.; Diogo, F.; Dobrigkeit, C.; Docters, W.; D’Olivo, J. C.; Dorofeev, A.; Dorosti Hasankiadeh, Q.; Dova, M. T.; Ebr, J.; Engel, R.; Erdmann, M.; Erfani, M.; Escobar, C. O.; Espadanal, J.; Etchegoyen, A.; Facal San Luis, P.; Falcke, H.; Fang, K.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Ferguson, A. P.; Fernandes, M.; Fick, B.; Figueira, J. M.; Filevich, A.; Filipčič, A.; Fox, B. D.; Fratu, O.; Fröhlich, U.; Fuchs, B.; Fuji, T.; Gaior, R.; García, B.; Garcia Roca, S. T.; Garcia-Gamez, D.; Garcia-Pinto, D.; Garilli, G.; Gascon Bravo, A.; Gate, F.; Gemmeke, H.; Ghia, P. L.; Giaccari, U.; Giammarchi, M.; Giller, M.; Glaser, C.; Glass, H.; Gómez Berisso, M.; Gómez Vitale, P. F.; Gonçalves, P.; Gonzalez, J. G.; González, N.; Gookin, B.; Gordon, J.; Gorgi, A.; Gorham, P.; Gouffon, P.; Grebe, S.; Griffith, N.; Grillo, A. F.; Grubb, T. D.; Guarino, F.; Guedes, G. P.; Hampel, M. R.; Hansen, P.; Harari, D.; Harrison, T. A.; Hartmann, S.; Harton, J. L.; Haungs, A.; Hebbeker, T.; Heck, D.; Heimann, P.; Herve, A. E.; Hill, G. C.; Hojvat, C.; Hollon, N.; Holt, E.; Homola, P.; Hörandel, J. R.; Horvath, P.; Hrabovský, M.; Huber, D.; Huege, T.; Insolia, A.; Isar, P. G.; Jandt, I.; Jansen, S.; Jarne, C.; Josebachuili, M.; Kääpä, A.; Kambeitz, O.; Kampert, K. H.; Kasper, P.; Katkov, I.; Kégl, B.; Keilhauer, B.; Keivani, A.; Kemp, E.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Krause, R.; Krohm, N.; Krömer, O.; Kruppke-Hansen, D.; Kuempel, D.; Kunka, N.; LaHurd, D.; Latronico, L.; Lauer, R.; Lauscher, M.; Lautridou, P.; Le Coz, S.; Leão, M. S. A. B.; Lebrun, D.; Lebrun, P.; Leigui de Oliveira, M. A.; Letessier-Selvon, A.; Lhenry-Yvon, I.; Link, K.; López, R.; Lopez Agüera, A.; Louedec, K.; Lozano Bahilo, J.; Lu, L.; Lucero, A.; Ludwig, M.; Malacari, M.; Maldera, S.; Mallamaci, M.; Maller, J.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Marin, V.; Mariş, I. C.; Marsella, G.; Martello, D.; Martin, L.; Martinez, H.; Martínez Bravo, O.; Martraire, D.; Masías Meza, J. J.; Mathes, H. J.; Mathys, S.; Matthews, J.; Matthews, J. A. J.; Matthiae, G.; Maurel, D.; Maurizio, D.; Mayotte, E.; Mazur, P. O.; Medina, C.; Medina-Tanco, G.; Meissner, R.; Melissas, M.; Melo, D.; Menshikov, A.; Messina, S.; Meyhandan, R.; Mićanović, S.; Micheletti, M. I.; Middendorf, L.; Minaya, I. A.; Miramonti, L.; Mitrica, B.; Molina-Bueno, L.; Mollerach, S.; Monasor, M.; Monnier Ragaigne, D.; Montanet, F.; Morello, C.; Mostafá, M.; Moura, C. A.; Muller, M. A.; Müller, G.; Müller, S.; Münchmeyer, M.; Mussa, R.; Navarra, G.; Navas, S.; Necesal, P.; Nellen, L.; Nelles, A.; Neuser, J.; Nguyen, P.; Niechciol, M.; Niemietz, L.; Niggemann, T.; Nitz, D.; Nosek, D.; Novotny, V.; Nožka, L.; Ochilo, L.; Olinto, A.; Oliveira, M.; Pacheco, N.; Pakk Selmi-Dei, D.; Palatka, M.; Pallotta, J.; Palmieri, N.; Papenbreer, P.; Parente, G.; Parra, A.; Paul, T.; Pech, M.; Pȩkala, J.; Pelayo, R.; Pepe, I. M.; Perrone, L.; Petermann, E.; Peters, C.; Petrera, S.; Petrov, Y.; Phuntsok, J.; Piegaia, R.; Pierog, T.; Pieroni, P.; Pimenta, M.; Pirronello, V.; Platino, M.; Plum, M.; Porcelli, A.; Porowski, C.; Prado, R. R.; Privitera, P.; Prouza, M.; Purrello, V.; Quel, E. J.; Querchfeld, S.; Quinn, S.; Rautenberg, J.; Ravel, O.; Ravignani, D.; Revenu, B.; Ridky, J.; Riggi, S.; Risse, M.; Ristori, P.; Rizi, V.; Rodrigues de Carvalho, W.; Rodriguez Cabo, I.; Rodriguez Fernandez, G.; Rodriguez Rojo, J.; Rodríguez-Frías, M. D.; Rogozin, D.; Ros, G.; Rosado, J.; Rossler, T.; Roth, M.; Roulet, E.; Rovero, A. C.; Saffi, S. J.; Saftoiu, A.; Salamida, F.; Salazar, H.; Saleh, A.; Salesa Greus, F.; Salina, G.; Sánchez, F.; Sanchez-Lucas, P.; Santo, C. E.; Santos, E.; Santos, E. M.; Sarazin, F.; Sarkar, B.; Sarmento, R.; Sato, R.; Scharf, N.; Scherini, V.; Schieler, H.; Schiffer, P.; Schmidt, D.; Scholten, O.; Schoorlemmer, H.; Schovánek, P.; Schulz, A.; Schulz, J.; Schumacher, J.; Sciutto, S. J.; Segreto, A.; Settimo, M.; Shadkam, A.; Shellard, R. C.; Sidelnik, I.; Sigl, G.; Sima, O.; Śmiałkowski, A.; Šmída, R.; Snow, G. R.; Sommers, P.; Sorokin, J.; Squartini, R.; Srivastava, Y. N.; Stanič, S.; Stapleton, J.; Stasielak, J.; Stephan, M.; Stutz, A.; Suarez, F.; Suomijärvi, T.; Supanitsky, A. D.; Sutherland, M. S.; Swain, J.; Szadkowski, Z.; Szuba, M.; Taborda, O. A.; Tapia, A.; Tartare, M.; Tepe, A.; Theodoro, V. M.; Timmermans, C.; Todero Peixoto, C. J.; Toma, G.; Tomankova, L.; Tomé, B.; Tonachini, A.; Torralba Elipe, G.; Torres Machado, D.; Travnicek, P.; Trovato, E.; Tueros, M.; Ulrich, R.; Unger, M.; Urban, M.; Valdés Galicia, J. F.; Valiño, I.; Valore, L.; van Aar, G.; van Bodegom, P.; van den Berg, A. M.; van Velzen, S.; van Vliet, A.; Varela, E.; Vargas Cárdenas, B.; Varner, G.; Vázquez, J. R.; Vázquez, R. A.; Veberič, D.; Verzi, V.; Vicha, J.; Videla, M.; Villaseñor, L.; Vlcek, B.; Vorobiov, S.; Wahlberg, H.; Wainberg, O.; Walz, D.; Watson, A. A.; Weber, M.; Weidenhaupt, K.; Weindl, A.; Werner, F.; Widom, A.; Wiencke, L.; Wilczyńska, B.; Wilczyński, H.; Will, M.; Williams, C.; Winchen, T.; Wittkowski, D.; Wundheiler, B.; Wykes, S.; Yamamoto, T.; Yapici, T.; Yuan, G.; Yushkov, A.; Zamorano, B.; Zas, E.; Zavrtanik, D.; Zavrtanik, M.; Zaw, I.; Zepeda, A.; Zhou, J.; Zhu, Y.; Zimbres Silva, M.; Ziolkowski, M.; Zuccarello, F.

    2014-12-01

    Using the data taken at the Pierre Auger Observatory between December 2004 and December 2012, we have examined the implications of the distributions of depths of atmospheric shower maximum (Xmax), using a hybrid technique, for composition and hadronic interaction models. We do this by fitting the distributions with predictions from a variety of hadronic interaction models for variations in the composition of the primary cosmic rays and examining the quality of the fit. Regardless of what interaction model is assumed, we find that our data are not well described by a mix of protons and iron nuclei over most of the energy range. Acceptable fits can be obtained when intermediate masses are included, and when this is done consistent results for the proton and iron-nuclei contributions can be found using the available models. We observe a strong energy dependence of the resulting proton fractions, and find no support from any of the models for a significant contribution from iron nuclei. However, we also observe a significant disagreement between the models with respect to the relative contributions of the intermediate components.

  3. An observed link between lithophile compositions and degassing of volatiles (He, Ar, CO2) in MORBs with implications for Re volatility and the mantle C/Nb ratio

    NASA Astrophysics Data System (ADS)

    Burnard, Pete; Reisberg, Laurie; Colin, Aurélia

    2014-06-01

    There are systematic variations between relative noble gas abundances and lithophile tracers such as 87Sr/86Sr, εNd and La/Sm in a suite of basaltic glasses from the South East Indian Ridge (SEIR). 4He/40Ar* (where 40Ar* is 40Ar corrected for atmospheric contamination) correlates positively with 87Sr/86Sr and La/Sm but anticorrelates with εNd. The large range in 4He/40Ar* observed in the glasses is due to fractionation during magmatic degassing caused by the very different solubilities of He and Ar in silicate liquids, whereas 87Sr/86Sr, εNd, La/Sm, etc. are insensitive to magmatic processes but rather reflect mantle heterogeneity. Thus, there is a curious situation in this suite of basalts where tracers of mantle heterogeneity (87Sr/86Sr, εNd, La/Sm, etc.) correlate with a tracer of magmatic volatile processes (4He/40Ar*). Here, we propose that “enriched” mantle (with high La/Sm and 87Sr/86Sr, low εNd) also has a higher C concentration than “depleted” mantle. Magmas derived from enriched mantle will therefore have higher initial C concentrations, leading to a greater fraction of CO2 degassed and thus a higher 4He/40Ar* ratio on eruption. Simple solubility-determined fractional degassing models show that the range in 4He/40Ar* observed in SEIR basaltic glasses can be generated if the mantle C concentration varies by a factor of 2 over the length of the ridge, consistent with independent estimates of C concentration heterogeneity in the MORB mantle. The correlations between lithophile tracers and 4He/40Ar* can be reproduced by mixing between a depleted endmember with 87Sr/86Sr = 0.70275, εNd = 8.2 and [C] = 12 ppm and an enriched endmember with 87Sr/86Sr = 0.70360, εNd = 5 and [C] = 24 ppm, followed by degassing. The proposed degassing model allows us to estimate the initial C concentration (i.e. prior to degassing) of each SEIR basalt (for which Sr or Nd isotopes are available); using independent Nb concentration data (Mahoney et al., 2002), we show

  4. Noninvasive in vivo plasma volume and hematocrit in humans: observing long-term baseline behavior to establish homeostasis for intravascular volume and composition

    NASA Astrophysics Data System (ADS)

    Dent, Paul; Deng, Bin; Goodisman, Jerry; Peterson, Charles M.; Narsipur, Sriram; Chaiken, J.

    2016-04-01

    A new device incorporating a new algorithm and measurement process allows simultaneous noninvasive in vivo monitoring of intravascular plasma volume and red blood cell volume. The purely optical technique involves probing fingertip skin with near infrared laser light and collecting the wavelength shifted light, that is, the inelastic emission (IE) which includes the unresolved Raman and fluorescence, and the un-shifted emission, that is, the elastic emission (EE) which includes both the Rayleigh and Mie scattered light. Our excitation and detection geometry is designed so that from these two simultaneous measurements we can calculate two parameters within the single scattering regime using radiation transfer theory, the intravascular plasma volume fraction and the red blood cell volume fraction. Previously calibrated against a gold standard FDA approved device, 2 hour monitoring sessions on three separate occasions over a three week span for a specific, motionless, and mostly sleeping individual produced 3 records containing a total of 5706 paired measurements of hematocrit and plasma volume. The average over the three runs, relative to the initial plasma volume taken as 100%, of the plasma volume±1σ was 97.56+/-0.55 or 0.56%.For the same three runs, the average relative hematocrit (Hct), referenced to an assumed initial value of 28.35 was 29.37+/-0.12 or stable to +/-0.4%.We observe local deterministic circulation effects apparently associated with the pressure applied by the finger probe as well as longer timescale behavior due to normal ebb and flow of internal fluids due to posture changes and tilt table induced gravity gradients.

  5. KECK AND VLT OBSERVATIONS OF SUPER-DAMPED Lyα ABSORBERS AT z ∼ 2–2.5: CONSTRAINTS ON CHEMICAL COMPOSITIONS AND PHYSICAL CONDITIONS

    SciTech Connect

    Kulkarni, Varsha P.; Som, Debopam; Morrison, Sean; Péroux, Celine; Quiret, Samuel; York, Donald G.

    2015-12-10

    We report Keck/Echellette Spectrograph and Imager and Very Large Telescope/Ultraviolet-Visual Echelle Spectrograph observations of three super-damped Lyα quasar absorbers with H i column densities log N{sub H} {sub i} ≥ 21.7 at redshifts 2 ≲ z ≲ 2.5. All three absorbers show similar metallicities (∼−1.3 to −1.5 dex), and dust depletion of Fe, Ni, and Mn. Two of the absorbers show supersolar [S/Zn] and [Si/Zn]. We combine our results with those for other damped Lyα a absorbers (DLAs) to examine trends between N{sub H} {sub i}, metallicity, and dust depletion. A larger fraction of the super-DLAs lie close to or above the line [X/H] = 20.59 − log N{sub H} {sub i} in the metallicity versus N{sub H} {sub i} plot, compared to the less gas-rich DLAs, suggesting that super-DLAs are more likely to be rich in molecules. Unfortunately, our data for Q0230−0334 and Q0743+1421 do not cover H{sub 2} absorption lines. For Q1418+0718, some H{sub 2} lines are covered, but not detected. CO is not detected in any of our absorbers. For DLAs with log N{sub H} {sub i} < 21.7, we confirm strong correlation between metallicity and Fe depletion, and find a correlation between metallicity and Si depletion. For super-DLAs, these correlations are weaker or absent. The absorbers toward Q0230−0334 and Q1418+0718 show potential detections of weak Lyα emission, implying star formation rates of ∼1.6 and ∼0.7 M{sub ⊙} yr{sup −1}, respectively (ignoring dust extinction). Upper limits on the electron densities from C ii*/C ii or Si ii*/Si ii are low, but are higher than the median values in less gas-rich DLAs. Finally, systems with log N{sub H} {sub i} > 21.7 may have somewhat narrower velocity dispersions Δv{sub 90} than the less gas-rich DLAs, and may arise in cooler and/or less turbulent gas.

  6. The impact of Mount Etna's sulphur emissions to the atmospheric composition, aerosol properties and radiative transfer in the central Mediterranean: 14 years of statistic analysis using observations and Lagrangian modelling

    NASA Astrophysics Data System (ADS)

    Sellitto, Pasquale; Zanetel, Claudia; di Sarra, Alcide; Salerno, Giuseppe; Tapparo, Andrea; Briole, Pierre; Legras, Bernard

    2016-04-01

    Volcanic eruptions influence tropospheric and stratospheric composition, the Earth's radiation budget from the regional to the global scale, and then the Earth's climate. While the impact of the strong explosive eruptions reaching the stratosphere is relatively well known, the influence of the more frequent weak volcanic activity, including passive degassing, on the tropospheric aerosol properties and on the radiation budget is still largely unknown. Most of the radiative effects of moderate eruptions are associated with changes of the aerosol size distribution, composition, and shape. Emission of primary particles, mainly ash, and secondary aerosols through gas-to-particle conversion of volatile sulphur compounds contribute to affect the aerosol properties. Mount Etna's continuous degassing and episodic explosive eruptions is an important source of particles and gases for the Mediterranean atmosphere, with, e.g., ten times larger emissions of volatile sulphur compounds than the anthropogenic sulphur emissions in the Mediterranean area. The impact of Mount Etna on the atmospheric composition, the aerosol chemical, microphysical and optical properties, the clouds occurrence and properties, the radiative balance and the regional climate in the Mediterranean are not known and probably underestimated. In this contribution, the downwind impact of Mount Etna's sulphur emissions in the central Mediterranean is estimated over the period 2000-2013 using long-term series of sulphur dioxide column and Ångströms exponent observations at the the ENEA (Ente Nazionale per l'Energia e l'Ambiente) Station for Climate Observations on the small island of Lampedusa (35.5°N, 12.6°E). These observations are linked to the information on the volcanic source, in terms of 1) the local dynamics, using a long series of trajectories and plume dispersion information obtained with the FLEXPART Lagrangian mode, and 2) the emission strength, using the long-term series of daily sulphur dioxide

  7. Search for rapid angular and energy dependence of dsigma/d. cap omega. and iT/sub 11/ in large angle. pi. -d elastic scattering

    SciTech Connect

    Mathie, E.L.; Smith, G.R.; Boschitz, E.T.; Meyer, M.; Vogler, F.; Daum, M.; Mango, S.; Konter, J.A.

    1983-12-01

    The ..pi..-d elastic differential cross-section and the vector analyzing power have been measured between CTHETA/sub c.m./ = 95/sup 0/ and 165/sup 0/ at incident pion energies between 117 and 151 MeV. Both observables show a smooth behavior as a function of angle and energy.

  8. Occurrence of electrical percolation threshold and observation of phase transition in chitosan(1- x):AgI x (0.05 ≤ x ≤ 0.2)-based ion-conducting solid polymer composites

    NASA Astrophysics Data System (ADS)

    Aziz, Shujahadeen B.

    2016-07-01

    This paper reports on the investigation of electrical percolation threshold and ion transport mechanism for ion-conducting solid polymer composites based on chitosan. The composite samples were prepared by solution cast technique. The result of DC conductivity versus percolation threshold (Φ^{ - 1/3} ) confirmed that at low AgI concentration, the tunneling effect governs ionic conduction mechanism. Nevertheless, at high filler concentration, the DC conductivity showed a plateau behavior. The DC conductivity as a function of reciprocal temperature revealed that the ion conduction mechanism is slightly temperature dependent and the ion-ion correlational effect is dominant. A steep increase in DC conductivity above 323 K is observed, which indicated the existence of some phase transition near the beta (β)-phase. The drop of DC conductivity at high temperatures is anticipated from the impedance plots. The AC conductivity spectrum exhibited three distinct regions at low temperatures. The high-frequency regions of AC conductivity spectra were almost temperature independent at low temperatures (303-323 K) and obeyed the Jonscher's power law. The variation in frequency exponent versus temperature reveals that ion conduction mechanism follows QMT and CBH models at low and high temperatures, respectively. The valuable achievement of this work is that the temperature dependence of DC conductivity and the frequency exponent ( s) is correlated to interpret the Ag+ ion dynamic and ion-ion correlational effect. The Argand plots were used to explain the relaxation processes.

  9. Constraining the size of the Comptonizing medium by modelling the energy-dependent time lags of kHz QPOs of neutron star system

    NASA Astrophysics Data System (ADS)

    Kumar, Nagendra; Misra, Ranjeev

    2016-09-01

    We study the dependence of the estimated size and geometry of the medium on the time-averaged spectral model assumed and on the frequency of the kHz quasi-periodic oscillation (QPO) in the framework of a thermal Comptonization model. We use the high-quality time lag and rms obtained during 1996 March 3 observation of 4U 1608-52 by RXTE as well as other observations of the source at different QPO frequencies where a single time lag between two broad energy bands has been reported. We compare the results obtained when assuming that the time-averaged spectra are represented by the spectrally degenerate `hot (kTb ≥ 1 keV)' and `cold (kTb ≤ 0.5 keV)' seed spectral models where Tb is seed source temperature. We find that for the `hot-seed' model the medium size is in the range of 0.3-2.0 km and the size decreases with increasing QPO frequency. On the other hand, for the `cold-seed' model, the range for the sizes is much larger 0.5-20 km and hence perhaps show no variation with QPO frequency. Our results emphasize the need for broad-band spectral information combined with high-frequency timing to lift this degeneracy. We further compare the rms as a function of energy for the upper kHz QPO, and indeed we find that the driver for this QPO should be temperature variations of the corona identical to the lower kHz QPO. However, the time lag reported for the upper kHz QPO is hard, which if confirmed would challenge the simple Comptonization model presented here.

  10. The C-S-H gel of Portland cement mortars: Part I. The interpretation of energy-dispersive X-ray microanalyses from scanning electron microscopy, with some observations on C-S-H, AFm and AFt phase compositions

    SciTech Connect

    Famy, C.; Brough, A.R.; Taylor, H.F.W

    2003-09-01

    Scanning electron microscopy (SEM) microanalyses of the calcium-silicate-hydrate (C-S-H) gel in Portland cement pastes rarely represent single phases. Essential experimental requirements are summarised and new procedures for interpreting the data are described. These include, notably, plots of Si/Ca against other atom ratios, 3D plots to allow three such ratios to be correlated and solution of linear simultaneous equations to test and quantify hypotheses regarding the phases contributing to individual microanalyses. Application of these methods to the C-S-H gel of a 1-day-old mortar identified a phase with Al/Ca=0.67 and S/Ca=0.33, which we consider to be a highly substituted ettringite of probable composition C{sub 6}A{sub 2}S-bar{sub 2}H{sub 34} or {l_brace}Ca{sub 6}[Al(OH){sub 6}]{sub 2}{center_dot}24H{sub 2}O{r_brace}(SO{sub 4}){sub 2}[Al(OH){sub 4}]{sub 2}. If this is true for Portland cements in general, it might explain observed discrepancies between observed and calculated aluminate concentrations in the pore solution. The C-S-H gel of a similar mortar aged 600 days contained unsubstituted ettringite and an AFm phase with S/Ca=0.125.

  11. A STUDY OF THE ENERGY DEPENDENCE OF RADIATION DAMAGE IN SUPERCONDUCTING COILS FOR A NEXT GENERATION MU2E AT PIP - II

    SciTech Connect

    Pronskikh, V.; Glenzinski, D.; Knoepfel, K.; Mokhov, N.; Tschirhart, Tschirhart

    2016-04-01

    The Mu2e experiment at Fermilab is being designed to study the coherent neutrino-less conversion of a negative muon into an electron in the field of a nucleus. This process has an extremely low probability in the Standard Model, and its observation would provide unambiguous evidence for beyond the standard model physics. The Mu2e design aims to reach a single-event-sensitivity of about 2.5 x $10^{-17}$ and will probe effective new physics mass scales in the $10^{3}-10^{4}$ TeV range, well beyond the reach of the LHC. This work will examine the maximum beam power that can be tolerated for beam energies in the 0.5-8 GeV range. This has implications for how the sensitivity might be further improved with a second generation experiment using an upgraded proton beam from the PIP-II project, which will be capable of providing MW beams to Fermilab experiments later in the next decade.

  12. Energy dependence of localization with interactions and disorder: The generalized inverse participation ratio of an ensemble of two-site Anderson-Hubbard systems

    NASA Astrophysics Data System (ADS)

    Wortis, Rachel; Perera, Jayanayana

    2015-03-01

    We explore the effect of interactions on novel features found in non-interacting disordered systems. Johri and Bhatt [PRL 109 076402 (2012), PRB 86 125140 (2012)] showed that for non-interacting particles moving in a disordered potential Lifshitz states lead to a decrease in localization at the band edges. This is reflected in an abrupt decline in the inverse participation ratio following a sharp peak. We consider an ensemble of two-site Anderson-Hubbard systems and study a generalization of the inverse participation ratio applicable to interacting systems. With on-site Coulomb repulsion U, two types of resonances can occur: As in the non-interacting case, the potentials at the two sites may be similar. In addition, the potential at one site may differ from its neighbor by U. We demonstrate that these two types of resonance and the diversity of transitions in the interacting case result in much more varied dependence of localization on energy, with multiple local minima, including a strong suppression and more structure near the Fermi level. Opportunities for experimental observation are considered. NSERC of Canada.

  13. Beam-energy dependence of charge balance functions from Au + Au collisions at energies available at the BNL Relativistic Heavy Ion Collider

    DOE PAGES

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; ...

    2016-08-16

    Balance functions have been measured in terms of relative pseudorapidity ( Δη ) for charged particle pairs at the BNL Relativistic Heavy Ion Collider (RHIC) from Au + Au collisions atmore » $$\\sqrt{s}$$$_{NN}$$ = 7.7 GeV to 200 GeV using the STAR detector. These results are compared with balance functions measured at the CERN Large Hadron Collider from Pb + Pb collisions at $$\\sqrt{s}$$$_{NN}$$ = 2.76 TeV by the ALICE Collaboration. The width of the balance function decreases as the collisions become more central and as the beam energy is increased. In contrast, the widths of the balance functions calculated using shuffled events show little dependence on centrality or beam energy and are larger than the observed widths. Balance function widths calculated using events generated by UrQMD are wider than the measured widths in central collisions and show little centrality dependence. The measured widths of the balance functions in central collisions are consistent with the delayed hadronization of a deconfined quark gluon plasma (QGP). Finally, the narrowing of the balance function in central collisions at $$\\sqrt{s}$$$_{NN}$$ = 7.7 GeV implies that a QGP is still being created at this relatively low energy.« less

  14. Beam-energy dependence of charge balance functions from Au + Au collisions at energies available at the BNL Relativistic Heavy Ion Collider

    SciTech Connect

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Alford, J.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Averichev, G. S.; Banerjee, A.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Bouchet, J.; Brandin, A. V.; Bunzarov, I.; Burton, T. P.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Campbell, J. M.; Cebra, D.; Cervantes, M. C.; Chakaberia, I.; Chaloupka, P.; Chang, Z.; Chattopadhyay, S.; Chen, J. H.; Chen, H. F.; Cheng, J.; Cherney, M.; Christie, W.; Codrington, M. J. M.; Contin, G.; Crawford, H. J.; Cui, X.; Das, S.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; Derradi de Souza, R.; di Ruzza, B.; Didenko, L.; Dilks, C.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Engelage, J.; Eppley, G.; Esha, R.; Evdokimov, O.; Eyser, O.; Fatemi, R.; Fazio, S.; Federic, P.; Fedorisin, J.; Feng,; Filip, P.; Fisyak, Y.; Flores, C. E.; Gagliardi, C. A.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Greiner, L.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, A.; Gupta, S.; Guryn, W.; Hamad, A.; 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, X.; Huang, H. Z.; 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.; Khan, Z. H.; Kikola, D. P.; Kisel, I.; Kisiel, A.; Klein, S. R.; Koetke, D. D.; Kollegger, T.; Kosarzewski, L. K.; 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.; Li, Z. M.; Li, X.; Li, W.; Li, Y.; Li, X.; Li, C.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, X.; Ma, G. L.; Ma, R. M.; Ma, Y. G.; Magdy, N.; Mahapatra, D. P.; Majka, R.; Manion, A.; Margetis, S.; Markert, C.; Masui, H.; Matis, H. S.; McDonald, D.; Minaev, N. G.; Mioduszewski, S.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nigmatkulov, G.; Nogach, L. V.; Noh, S. Y.; Novak, J.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Okorokov, V.; Olvitt, D. L.; Page, B. S.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlak, T.; Pawlik, B.; Pei, H.; Perkins, C.; Pile, P.; Planinic, M.; Pluta, J.; Poljak, N.; Poniatowska, K.; Porter, J.; Poskanzer, A. M.; Pruthi, N. K.; Przybycien, M.; Putschke, J.; Qiu, H.; Quintero, A.; Ramachandran, S.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Roy, A.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandacz, A.; Sandweiss, J.; 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.; Simko, M.; Skoby, M. J.; Smirnov, N.; Smirnov, D.; Solanki, D.; Song, L.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Sumbera, M.; Summa, B. J.; Sun, X. M.; Sun, Z.; Sun, Y.; Sun, X.; Surrow, B.; Svirida, D. N.; Szelezniak, M. A.; Takahashi, J.; Tang, Z.; Tang, A. H.; Tarnowsky, T.; Tawfik, A. N.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Tripathy, S. K.; Trzeciak, B. A.; Tsai, O. D.; Turnau, J.; Ullrich, T.; Underwood, D. G.; Upsal, I.; Van Buren, G.; van Nieuwenhuizen, G.; Vandenbroucke, M.; Varma, R.; Vasconcelos, G. M. S.; Vasiliev, A. N.; Vertesi, R.; Videbæk, F.; Viyogi, Y. P.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wang, J. S.; Wang, X. L.; Wang, Y.; Wang, H.; Wang, F.; Wang, G.; Webb, G.; Webb, J. C.; Wen, L.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y. F.; Xiao, Z.; Xie, W.; Xin, K.; Xu, N.; Xu, Z.; Xu, H.; Xu, Y.; Xu, Q. H.; Yan, W.; Yang, Y.; Yang, C.; Yang, Y.; Ye, Z.; Yepes, P.; Yi, L.; Yip, K.; Yoo, I. -K.; Yu, N.; Zbroszczyk, H.; Zha, W.; Zhang, X. P.; Zhang, Z. P.; Zhang, J. B.; Zhang, J. L.; Zhang, Y.; Zhang, S.; Zhao, F.; Zhao, J.; Zhong, C.; Zhu, Y. H.; Zhu, X.; Zoulkarneeva, Y.; Zyzak, M.

    2016-08-16

    Balance functions have been measured in terms of relative pseudorapidity ( Δη ) for charged particle pairs at the BNL Relativistic Heavy Ion Collider (RHIC) from Au + Au collisions at $\\sqrt{s}$$_{NN}$ = 7.7 GeV to 200 GeV using the STAR detector. These results are compared with balance functions measured at the CERN Large Hadron Collider from Pb + Pb collisions at $\\sqrt{s}$$_{NN}$ = 2.76 TeV by the ALICE Collaboration. The width of the balance function decreases as the collisions become more central and as the beam energy is increased. In contrast, the widths of the balance functions calculated using shuffled events show little dependence on centrality or beam energy and are larger than the observed widths. Balance function widths calculated using events generated by UrQMD are wider than the measured widths in central collisions and show little centrality dependence. The measured widths of the balance functions in central collisions are consistent with the delayed hadronization of a deconfined quark gluon plasma (QGP). Finally, the narrowing of the balance function in central collisions at $\\sqrt{s}$$_{NN}$ = 7.7 GeV implies that a QGP is still being created at this relatively low energy.

  15. Beam-energy dependence of charge balance functions from Au + Au collisions at energies available at the BNL Relativistic Heavy Ion Collider

    NASA Astrophysics Data System (ADS)

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Alford, J.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Averichev, G. S.; Banerjee, A.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Bouchet, J.; Brandin, A. V.; Bunzarov, I.; Burton, T. P.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Campbell, J. M.; Cebra, D.; Cervantes, M. C.; Chakaberia, I.; Chaloupka, P.; Chang, Z.; Chattopadhyay, S.; Chen, J. H.; Chen, H. F.; Cheng, J.; Cherney, M.; Christie, W.; Codrington, M. J. M.; Contin, G.; Crawford, H. J.; Cui, X.; Das, S.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; Derradi de Souza, R.; di Ruzza, B.; Didenko, L.; Dilks, C.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Engelage, J.; Eppley, G.; Esha, R.; Evdokimov, O.; Eyser, O.; Fatemi, R.; Fazio, S.; Federic, P.; Fedorisin, J.; Feng, Filip, P.; Fisyak, Y.; Flores, C. E.; Gagliardi, C. A.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Greiner, L.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, A.; Gupta, S.; Guryn, W.; Hamad, A.; 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, X.; Huang, H. Z.; 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.; Khan, Z. H.; Kikola, D. P.; Kisel, I.; Kisiel, A.; Klein, S. R.; Koetke, D. D.; Kollegger, T.; Kosarzewski, L. K.; 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.; Li, Z. M.; Li, X.; Li, W.; Li, Y.; Li, X.; Li, C.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, X.; Ma, G. L.; Ma, R. M.; Ma, Y. G.; Magdy, N.; Mahapatra, D. P.; Majka, R.; Manion, A.; Margetis, S.; Markert, C.; Masui, H.; Matis, H. S.; McDonald, D.; Minaev, N. G.; Mioduszewski, S.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nigmatkulov, G.; Nogach, L. V.; Noh, S. Y.; Novak, J.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Okorokov, V.; Olvitt, D. L.; Page, B. S.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlak, T.; Pawlik, B.; Pei, H.; Perkins, C.; Pile, P.; Planinic, M.; Pluta, J.; Poljak, N.; Poniatowska, K.; Porter, J.; Poskanzer, A. M.; Pruthi, N. K.; Przybycien, M.; Putschke, J.; Qiu, H.; Quintero, A.; Ramachandran, S.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Roy, A.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandacz, A.; Sandweiss, J.; 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.; Simko, M.; Skoby, M. J.; Smirnov, N.; Smirnov, D.; Solanki, D.; Song, L.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Sumbera, M.; Summa, B. J.; Sun, X. M.; Sun, Z.; Sun, Y.; Sun, X.; Surrow, B.; Svirida, D. N.; Szelezniak, M. A.; Takahashi, J.; Tang, Z.; Tang, A. H.; Tarnowsky, T.; Tawfik, A. N.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Tripathy, S. K.; Trzeciak, B. A.; Tsai, O. D.; Turnau, J.; Ullrich, T.; Underwood, D. G.; Upsal, I.; Van Buren, G.; van Nieuwenhuizen, G.; Vandenbroucke, M.; Varma, R.; Vasconcelos, G. M. S.; Vasiliev, A. N.; Vertesi, R.; Videbæk, F.; Viyogi, Y. P.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wang, J. S.; Wang, X. L.; Wang, Y.; Wang, H.; Wang, F.; Wang, G.; Webb, G.; Webb, J. C.; Wen, L.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y. F.; Xiao, Z.; Xie, W.; Xin, K.; Xu, N.; Xu, Z.; Xu, H.; Xu, Y.; Xu, Q. H.; Yan, W.; Yang, Y.; Yang, C.; Yang, Y.; Ye, Z.; Yepes, P.; Yi, L.; Yip, K.; Yoo, I.-K.; Yu, N.; Zbroszczyk, H.; Zha, W.; Zhang, X. P.; Zhang, Z. P.; Zhang, J. B.; Zhang, J. L.; Zhang, Y.; Zhang, S.; Zhao, F.; Zhao, J.; Zhong, C.; Zhu, Y. H.; Zhu, X.; Zoulkarneeva, Y.; Zyzak, M.; STAR Collaboration

    2016-08-01

    Balance functions have been measured in terms of relative pseudorapidity (Δ η ) for charged particle pairs at the BNL Relativistic Heavy Ion Collider from Au + Au collisions at √{sNN}=7.7 GeV to 200 GeV using the STAR detector. These results are compared with balance functions measured at the CERN Large Hadron Collider from Pb + Pb collisions at √{sNN}=2.76 TeV by the ALICE Collaboration. The width of the balance function decreases as the collisions become more central and as the beam energy is increased. In contrast, the widths of the balance functions calculated using shuffled events show little dependence on centrality or beam energy and are larger than the observed widths. Balance function widths calculated using events generated by UrQMD are wider than the measured widths in central collisions and show little centrality dependence. The measured widths of the balance functions in central collisions are consistent with the delayed hadronization of a deconfined quark gluon plasma (QGP). The narrowing of the balance function in central collisions at √{sNN}=7.7 GeV implies that a QGP is still being created at this relatively low energy.

  16. Measuring neutron star masses and radii using NICER observations of X-ray oscillations

    NASA Astrophysics Data System (ADS)

    Lamb, Frederick K.; Miller, M. Coleman

    2016-04-01

    Precise and reliable simultaneous measurements of the mass and radius of several neutron stars with different masses would provide valuable guidance for improving models of the properties of cold dense matter. The prime scientific goal of the Neutron star Interior Composition ExploreR (NICER) is to make such measurements by fitting energy-dependent waveform models to the thermal X-ray oscillations observed from rotation-powered millisecond pulsars. These oscillations are thought to be produced as hotter regions of the stellar surface near one or both of the star’s magnetic poles rotate around the star at the star's spin frequency. We first discuss the phenomenology and modeling of these oscillations. We then present the results of parameter estimation studies using synthetic waveform data and Bayesian statistical methods. The synthetic and model waveforms used in this study were computed using the X-ray spectra and radiation beaming patterns given by models of the cool hydrogen atmospheres that NICER is expected to observe. Finally, we discuss the causes and expected sizes of the uncertainties in radius and mass estimates that will be made by NICER using this method.

  17. Measuring the radius of PSR J0437 -4715 using NICER observations of X-ray oscillations

    NASA Astrophysics Data System (ADS)

    Lamb, Frederick; Miller, M. Coleman

    2017-01-01

    The Neutron Star Interior Composition Explorer (NICER) will launch early in 2017. Its first scientific objective is to precisely and reliably measure the radius of several neutron stars, thereby constraining the properties of cold matter at supranuclear densities. This will be done by fitting energy-dependent waveform models to the observed thermal X-ray waveforms of selected rotation-powered millisecond pulsars. A key target is the 174-Hz pulsar PSR J0437 -4715. Using synthetic waveform data and Bayesian methods, we have estimated the precisions with which its mass M and radius R can be measured by NICER. When generating the synthetic data, we assumed M = 1 . 4M⊙ and R = 13 km. When generating the data and when analyzing it, we assumed the X-ray spectrum and radiation beaming pattern given by models with cool hydrogen atmospheres and two hot spots. Assuming NICER observations lasting a total of 1.0 Msec, current knowledge of M and the distance, and knowledge of the pulsar's spin axis to within 1°, the 1 σ credible region in R extends from 11.83 to 13.73 km (7.4%) and in M, from 1.307 to 1.567 M⊙ (9.1%). Marginalizing over M, we find the 1 σ credible interval for R alone extends from 12.62 to 13.68 km (4%).

  18. The impact of Mount Etna sulfur emissions on the atmospheric composition and aerosol properties in the central Mediterranean: A statistical analysis over the period 2000-2013 based on observations and Lagrangian modelling

    NASA Astrophysics Data System (ADS)

    Sellitto, Pasquale; Zanetel, Claudia; di Sarra, Alcide; Salerno, Giuseppe; Tapparo, Andrea; Meloni, Daniela; Pace, Giandomenico; Caltabiano, Tommaso; Briole, Pierre; Legras, Bernard

    2017-01-01

    The emission of gases and aerosols due to volcanic activity may impact significantly atmospheric composition, cloud occurrence and properties, and the regional and global climate. While the effects of strong explosive (stratospheric) eruptions are relatively well known, limited information on the impacts of small to moderate volcanic activities, including passive degassing, is available. In this paper, the downwind impact of Mount Etna's sulfur emissions on the central Mediterranean is investigated on a statistical basis over the period 2000-2013 using: (a) daily sulfur dioxide emission rates measured near crater at Mount Etna with ground-based ultraviolet spectrophotometers, (b) Lagrangian trajectories and simulated plume dispersion obtained with the FLEXPART (FLEXible PARTicle dispersion) model, and (c) long-term observations of column SO2 concentration and aerosol Ångström exponent α at Lampedusa (35.5° N, 12.6° E). This statistical analysis has allowed, for the first time, the characterization of decadal impact of Mount Etna's sulfur emissions on the sulfur dioxide and the aerosol microphysical/optical properties in the central Mediterranean. On average, statistically significant higher SO2 concentrations and smaller aerosol sizes are present when air masses from Mount Etna overpass Lampedusa. Despite being upwind of Lampedusa for only 5% of the time, Mount Etna is potentially responsible for up to 40% and 20% of the SO2 and α extreme values (exceedances of a fixed threshold), respectively, at this location. The most important factor determining this perturbation is the prevailing dynamics, while the magnitude of the SO2 emission rates from Mount Etna appears to be likely important only for relatively strong emissions. The observed perturbations to the aerosol size distribution are expected to produce a direct regional radiative effect in this area.

  19. Novel spectro-electrochemical cell for in situ/operando observation of common composite electrode with liquid electrolyte by X-ray absorption spectroscopy in the tender X-ray region

    PubMed Central

    Nakanishi, Koji; Kato, Daisuke; Arai, Hajime; Tanida, Hajime; Mori, Takuya; Orikasa, Yuki; Uchimoto, Yoshiharu; Ohta, Toshiaki; Ogumi, Zempachi

    2014-01-01

    A novel spectro-electochemical cell for X-ray absorption spectroscopy in the tender X-ray region (TX-XAS) was designed and fabricated to investigate the electrochemical behavior of common battery materials with liquid electrolytes under in situ/operando conditions. The cell has several unique features, such as high X-ray transmittance, high signal to noise ratio, and high vacuum tightness. These features enable us quick and reliable XAS measurements. Operando P K-edge XAS measurements of an olivine-type LiFePO4 composite positive electrode were carried out to clarify its phosphorus environment during the electrochemical charging process. Results of spectral analysis show that there is no significant change in the oxidation state of phosphorus and in the coordination of the phosphate anions in the charging process, but a closer look of the consecutive XAS spectra suggests the shrinkage of the PO4 cage during the charging process, and the structural changes in a biphasic manner. These results demonstrate the usefulness of the cell for in situ/operando TX-XAS observations of light elements in practical batteries. PMID:25173283

  20. Synthesis of Compositionally Defined Single-Crystalline Eu 3+ -Activated Molybdate–Tungstate Solid-Solution Composite Nanowires and Observation of Charge Transfer in a Novel Class of 1D CaMoO 4 –CaWO 4 :Eu 3+ –0D CdS/CdSe QD Nanoscale Heterostructures

    SciTech Connect

    Han, Jinkyu; McBean, Coray; Wang, Lei; Jaye, Cherno; Liu, Haiqing; Fischer, Daniel A.; Wong, Stanislaus S.

    2015-02-10

    As a first step, we have synthesized and optically characterized a systematic series of one-dimensional (1D) single-crystalline Eu³⁺-activated alkaline-earth metal tungstate/molybdate solid solution composite CaW₁₋xMoxO₄ (0 ≤ ‘x’ ≤ 1) nanowires of controllable chemical composition using a modified template-directed methodology under ambient room-temperature conditions. Extensive characterization of the resulting nanowires has been performed using X-ray diffraction, electron microscopy, and optical spectroscopy. The crystallite size and single crystallinity of as-prepared 1D CaW₁₋xMoxO₄: Eu³⁺ (0 ≤ ‘x’ ≤ 1) solid solution composite nanowires increase with increasing Mo component (‘x’). We note a clear dependence of luminescence output upon nanowire chemical composition with our 1D CaW₁₋xMoxO₄: Eu³⁺ (0 ≤ ‘x’ ≤ 1) evincing the highest photoluminescence (PL) output at ‘x’ = 0.8, amongst samples tested. Subsequently, coupled with either zero-dimensional (0D) CdS or CdSe quantum dots (QDs), we successfully synthesized and observed charge transfer processes in 1D CaW1-xMoxO4: Eu3+ (‘x’ = 0.8) – 0D QD composite nanoscale heterostructures. Our results show that CaW₁₋xMoxO₄: Eu³⁺ (‘x’ = 0.8) nanowires give rise to PL quenching when CdSe QDs and CdS QDs are anchored onto the surfaces of 1D CaW₁₋xMoxO₄: Eu³⁺ nanowires. The observed PL quenching is especially pronounced in CaW₁₋xMoxO₄: Eu³⁺ (‘x’ = 0.8) – 0D CdSe QD heterostructures. Conversely, the PL output and lifetimes of CdSe and CdS QDs within these heterostructures are not noticeably altered as compared with unbound CdSe and CdS QDs. The difference in optical behavior between 1D Eu³⁺ activated tungstate and molybdate solid solution nanowires and the semiconducting 0D QDs within our

  1. Synthesis of Compositionally Defined Single-Crystalline Eu 3+ -Activated Molybdate–Tungstate Solid-Solution Composite Nanowires and Observation of Charge Transfer in a Novel Class of 1D CaMoO 4 –CaWO 4 :Eu 3+ –0D CdS/CdSe QD Nanoscale Heterostructures

    DOE PAGES

    Han, Jinkyu; McBean, Coray; Wang, Lei; ...

    2015-02-10

    As a first step, we have synthesized and optically characterized a systematic series of one-dimensional (1D) single-crystalline Eu³⁺-activated alkaline-earth metal tungstate/molybdate solid solution composite CaW₁₋xMoxO₄ (0 ≤ ‘x’ ≤ 1) nanowires of controllable chemical composition using a modified template-directed methodology under ambient room-temperature conditions. Extensive characterization of the resulting nanowires has been performed using X-ray diffraction, electron microscopy, and optical spectroscopy. The crystallite size and single crystallinity of as-prepared 1D CaW₁₋xMoxO₄: Eu³⁺ (0 ≤ ‘x’ ≤ 1) solid solution composite nanowires increase with increasing Mo component (‘x’). We note a clear dependence of luminescence output upon nanowire chemical composition withmore » our 1D CaW₁₋xMoxO₄: Eu³⁺ (0 ≤ ‘x’ ≤ 1) evincing the highest photoluminescence (PL) output at ‘x’ = 0.8, amongst samples tested. Subsequently, coupled with either zero-dimensional (0D) CdS or CdSe quantum dots (QDs), we successfully synthesized and observed charge transfer processes in 1D CaW1-xMoxO4: Eu3+ (‘x’ = 0.8) – 0D QD composite nanoscale heterostructures. Our results show that CaW₁₋xMoxO₄: Eu³⁺ (‘x’ = 0.8) nanowires give rise to PL quenching when CdSe QDs and CdS QDs are anchored onto the surfaces of 1D CaW₁₋xMoxO₄: Eu³⁺ nanowires. The observed PL quenching is especially pronounced in CaW₁₋xMoxO₄: Eu³⁺ (‘x’ = 0.8) – 0D CdSe QD heterostructures. Conversely, the PL output and lifetimes of CdSe and CdS QDs within these heterostructures are not noticeably altered as compared with unbound CdSe and CdS QDs. The difference in optical behavior between 1D Eu³⁺ activated tungstate and molybdate solid solution nanowires and the semiconducting 0D QDs within our heterostructures can be correlated with the relative positions of their conduction and valence energy band levels. We propose that

  2. Global Composite

    Atmospheric Science Data Center

    2013-04-19

    ... cover from one day to another. The lower panel is a composite in which red, green, and blue radiances from MISR's 70-degree ... In relatively clear ocean areas, the oblique-angle composite is generally brighter than its nadir counterpart due to enhanced ... Mar 2002 Images:  Global Composite location:  Global Images thumbnail:  ...

  3. Electrocatalyst compositions

    DOEpatents

    Mallouk, Thomas E.; Chan, Benny C.; Reddington, Erik; Sapienza, Anthony; Chen, Guoying; Smotkin, Eugene; Gurau, Bogdan; Viswanathan, Rameshkrishnan; Liu, Renxuan

    2001-09-04

    Compositions for use as catalysts in electrochemical reactions are described. The compositions are alloys prepared from two or more elemental metals selected from platinum, molybdenum, osmium, ruthenium, rhodium, and iridium. Also described are electrode compositions including such alloys and electrochemical reaction devices including such catalysts.

  4. Multiwavelength Observations of Mrk 501 in 2008

    SciTech Connect

    Kranich, D.; Paneque, D.; Cesarini, A.; Falcone, A.; Giroletti, M.; Hoversten, E.; Hovatta, T.; Kovalev, Y.Y.; Lahteenmaki, A.; Nieppola, E.; Pagani, C.; Pichel, A.; Satalecka, K.; Scargle, J.; Steele, D.; Tavecchio, F.; Tescaro, D.; Tornikoski, M.; Villata, M.; /Turin Observ.

    2010-08-25

    The well-studied VHE (E > 100 GeV) blazar Mrk 501 was observed between March and May 2008 as part of an extensive multiwavelength observation campaign including radio, optical, X-ray and VHE gamma-ray instruments. Mrk 501 was in a low state of activity during the campaign, with a low VHE flux of about 20% the Crab Nebula flux. Nevertheless, significant flux variations could be observed in X-rays as well as {gamma}-rays. Overall Mrk 501 showed increased variability when going from radio to {gamma}-ray energies. The broadband spectral energy distribution during the two different emission states of the campaign was well described by a homogeneous one-zone synchrotron self-Compton model. The high emission state was satisfactorily modeled by increasing the amount of high energy electrons with respect to the low emission state. This parameterization is consistent with the energy-dependent variability trend observed during the campaign.

  5. [Energy-dependent pathogenesis in chronic hypertension].

    PubMed

    Postnov, Iu V

    2009-01-01

    The review compiled mainly from the works of the author's laboratory continues to develop a new area in arterial hypertension studies. The author considers the major manifestation of the pathology, i. e. the stable increase in systemic blood pressure (BP), is in a direct causal relationship to cell and tissue energy deficiency. The energy deficiency is caused by impaired energy conversion in the cell mitochondria, uncoupling of oxidation and phosphorylation, and decreased ATP production. The cause of the latter in primary hypertension may be a mitochondrial calcium overload resulting from generalized abnormalities in membranous cytosol Ca2+ concentration regulation. In secondary forms of hypertension, uncoupling agents, such as thyroid hormones, angiotensin II, cyclosporine II, low temperatures, etc., may act as triggers of mitochondrial dysfunction. Hypertension begins with the activation of an efferent component of the sympathetic nervous system that supplies the vascular periphery. The sympathetic centers in the medulla oblongata seem to be involved in the activation process. Elevated systemic BP develops in order to compensate for ATF deficiency as a measure for correcting metabolic disturbances. Further systemic BP stabilization occurs with the involvement of the kidney that, exposed to elevated BP, begins functioning in a special switching (shifting) mode. Such a mode allows the kidney to avoid salt and water losses and at the same time to maintain the required (elevated) systemic BP, by affecting the mechanism of intrarenal regulation on the feedback principle. Resetting fixation takes place with the development of sclerotic changes in the kidney and hyalinosis in the renal medulla. Vascular system remodeling, including myocardial hypertrophic changes and capillary network rarefaction, is an essential element of BP stabilization. Hypertension becomes irreversible, by losing the features of compensatory and adaptive nature, and refractory to antihypertensive therapy.

  6. Composition of hot ions /0.1-16 keV/e/ as observed by the GEOS and ISEE mass spectrometers and inferences for the origin and circulation of magnetospheric plasmas

    NASA Technical Reports Server (NTRS)

    Balsiger, H.

    1981-01-01

    The composition of hot magnetospheric plasma through different regions of the magnetosphere is described on the basis of mass spectrometer measurements by the GEOS 1, GEOS 2, and ISEE-1 spacecraft. Coordinated composition measurements on the different spacecraft also provide information on the spatial and temporal characteristics of the plasma during storms. Data on ion origins are also provided.

  7. Composition of hot ions /0. 1-16 keV/e/ as observed by the GEOS and ISEE mass spectrometers and inferences for the origin and circulation of magnetospheric plasmas

    SciTech Connect

    Balsiger, H.

    1981-01-01

    The composition of hot magnetospheric plasma through different regions of the magnetosphere is described on the basis of mass spectrometer measurements by the GEOS 1, GEOS 2, and ISEE-1 spacecraft. Coordinated composition measurements on the different spacecraft also provide information on the spatial and temporal characteristics of the plasma during storms. Data on ion origins are also provided.

  8. Neon transport in selected organic composites. [stopping power of Kapton and polyethylene

    NASA Technical Reports Server (NTRS)

    Townsend, L. W.; Wilson, J. W.; Bidasaria, H. B.

    1984-01-01

    An energy-dependent, perturbation expansion solution for heavy-ion transport in one dimension was used to calculate the dose from Ne-20 beams at incident kinetic energies of 350, 670, and 2000 MeV/amu onto selected organic composites. Transport coefficients, applicable to arbitrary ion beams over a broad range of energies, are presented. Polyethylene and Kapton were tested as constituents of multilayered shielding for spacecraft and astronauts.

  9. Composite Materials

    NASA Technical Reports Server (NTRS)

    1985-01-01

    Composites are lighter and stronger than metals. Aramid fibers like Kevlar and Nomex were developed by DuPont Corporation and can be combined in a honeycomb structure which can give an airplane a light, tough structure. Composites can be molded into many aerodynamic shapes eliminating rivets and fasteners. Langley Research Center has tested composites for both aerospace and non-aerospace applications. They are also used in boat hulls, military shelters, etc.

  10. Composites review

    NASA Technical Reports Server (NTRS)

    Hordonneau, A.

    1987-01-01

    The properties and applications of composite materials are reviewed. Glass, carbon, Kevlar, ceramic, whisker, and metal fibers are discussed along with polyester, epoxy, polyimide, Peek, carbon, ceramic, and metal matrices. The quantitative distribution of high technology fiber in various applications is given. The role of aerospace industry in the development and promotion of composite utilization is discussed. Consumption trends indicate a rapid development of the composite market.

  11. Energetic composites

    DOEpatents

    Danen, Wayne C.; Martin, Joe A.

    1993-01-01

    A method for providing chemical energy and energetic compositions of matter consisting of thin layers of substances which will exothermically react with one another. The layers of reactive substances are separated by thin layers of a buffer material which prevents the reactions from taking place until the desired time. The reactions are triggered by an external agent, such as mechanical stress or an electric spark. The compositions are known as metastable interstitial composites (MICs). This class of compositions includes materials which have not previously been capable of use as energetic materials. The speed and products of the reactions can be varied to suit the application.

  12. Energetic composites

    DOEpatents

    Danen, W.C.; Martin, J.A.

    1993-11-30

    A method for providing chemical energy and energetic compositions of matter consisting of thin layers of substances which will exothermically react with one another. The layers of reactive substances are separated by thin layers of a buffer material which prevents the reactions from taking place until the desired time. The reactions are triggered by an external agent, such as mechanical stress or an electric spark. The compositions are known as metastable interstitial composites (MICs). This class of compositions includes materials which have not previously been capable of use as energetic materials. The speed and products of the reactions can be varied to suit the application. 3 figures.

  13. Composite floorpan

    SciTech Connect

    Frutiger, R.L.; Baskar, S.

    1993-02-01

    Composite applications for automotive components have been a topic of increased interest. Some applications--load-bearing composites such as bumpers and leaf springs--have been implemented successfully in production vehicles. On the other hand, semi-structural load-bearing composites such as floorpans have not been investigated as extensively for stiffness, strength, and durability. Past studies have used structural composites to achieve parts consolidation in van crossmembers. A rear floorpan has also been demonstrated in composites. A hybrid vehicle structure consisting of a composite passenger module on a steel frame has been proposed. Assessments of the energy management of full composite front structures have also been reported. There remains a need to assess structural composites for a major load-bearing panel with real-vehicle packaging and design requirements; a floorplan is one such application. This design concept might be used in a space-frame vehicle structure in which composite panels could be used to complete the structure and provide additional torsional rigidity while meeting local strength and stiffness requirements.

  14. Body Composition.

    ERIC Educational Resources Information Center

    Mayhew, Jerry L.

    1981-01-01

    Body composition refers to the types and amounts of tissues which make up the body. The most acceptable method for assessing body composition is underwater weighing. A subcutaneous skinfold provides a quantitative measurement of fat below the skin. The skinfold technique permits a valid estimate of the body's total fat content. (JN)

  15. Electrode compositions

    DOEpatents

    Block, J.; Fan, X.

    1998-10-27

    An electrode composition is described for use as an electrode in a non-aqueous battery system. The electrode composition contains an electrically active powder in a solid polymer and, as a dispersant, a C{sub 8}-C{sub 15} alkyl capped oligomer of a hexanoic acid that is electrochemically inert at 2.5--4.5 volts.

  16. Electrode compositions

    DOEpatents

    Block, Jacob; Fan, Xiyun

    1998-01-01

    An electrode composition for use as an electrode in a non-aqueous battery system. The electrode composition contains an electrically active powder in a solid polymer and, as a dispersant, a C.sub.8 -C.sub.15 alkyl capped oligomer of a hexanoic acid that is electrochemically inert at 2.5-4.5 volts.

  17. Summer atmospheric composition over the Mediterranean basin: Investigation on transport processes and pollutant export to the free troposphere by observations at the WMO/GAW Mt. Cimone global station (Italy, 2165 m a.s.l.)

    NASA Astrophysics Data System (ADS)

    Cristofanelli, P.; Landi, T. C.; Calzolari, F.; Duchi, R.; Marinoni, A.; Rinaldi, M.; Bonasoni, P.

    2016-09-01

    In this work, we analysed reactive gases (O3, CO, NOx) and aerosol properties (eqBC, σs and par