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Sample records for halo mg isotopic

  1. Search for halo nucleus in Mg isotopes through the measurements of reaction cross sections towards the vicinity of neutron drip line

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    Takechi M.

    2014-03-01

    Full Text Available Reaction cross sections (σR for 24–38Mg on C targets at the energies of around 240 MeV/nucleon have been measured precisely at RIBF, RIKEN for the purpose of obtaining the crucial information on the changes of nuclear structure in unstable nuclei, especially around the so-called “island of inversion” region. In the island of inversion region, which includes neutron-rich Ne, Na, and Mg isotopes, the vanishing of the N = 20 magic number for neutrons have been discussed along with nuclear deformation. The present result suggest deformation features of Mg isotopes and shows a large cross section of weakly-bound nucleus 37Mg, which could be caused by a neutron halo formation.

  2. Search for halo structure in 37Mg using the Glauber model and microscopic relativistic mean-field densities

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    Sharma, Mahesh K.; Panda, R. N.; Sharma, Manoj K.; Patra, S. K.

    2016-01-01

    We have studied the ground-state properties (binding energy and charge radius) using relativistic mean field formalism (RMF) for Mg isotopes from the valley of stability to the drip-line region. The RMF densities have been analyzed in the context of reaction dynamics. The results for Mg-4024+12C reactions at projectile energy of 240 MeV/nucleon are calculated using the Glauber model with the conjunction of densities from relativistic mean field formalism and compared with experimental data. We found nice agreement of estimated values of the reaction cross sections with the data values, except for the 37Mg isotope. In view of this, the halo status of 37Mg is examined through a higher magnitude of rms radius, one neutron removal cross section, and a small value of longitudinal momentum distribution. Finally, an effort is made to explore the structure of 37Mg halo candidate using Glauber many-body formalism.

  3. Mg Isotopes of USGS Igneous Rock Standards

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    Huang, F.; Glessner, J. J.; Lundstrom, C. C.

    2008-12-01

    Magnesium has three stable isotopes, 24Mg, 25Mg, and 26Mg with abundances of 78.99%, 10.00%, and 11.01%, respectively. It is one of the most abundant elements in the crust and mantle. As advancements of analytical techniques using MC-ICP-MS have dramatically advanced our ability to measure isotope ratios of Mg with greater precision, Mg isotopes can now be applied to study a variety of fundamental geological processes, such as continental crust weathering, chemical diffusion, and chondrule formation. Therefore the need for well characterized Mg isotope ratios for geological materials is increasingly important. Routine measurement of readily-available USGS rock standards is a viable way for inter-lab comparison to show the quality of data. However, the Mg isotope data for USGS standards reported in the literature are limited and inconsistent. USGS standards reported by different MC-ICP-MS labs have a range of Mg isotopic data outside of the normal external error of 0.1‰ (2σ). Mg isotopes of USGS igneous rock standards (dunite, DTS-1; basalts, BCR-1, BCR-2, BHVO-1; and andesite, AGV-1) were measured by a sample-standard bracketing method using a low resolution MC-ICP- MS (Nu-Plasma HR). The method has a large tolerance of matrix bias with Na/Mg and Al/Mg > 100% only changing the δ26Mg by less than 0.1‰. Dilution effects do not cause significant error (99.5%) and acceptable concentrations of matrix (mainly Na, Al, Ca, and Fe) are included in these results. Duplicate analyses of independently processed standards yielded the following results (δ26MgDSM-3 (‰)): BCR-2 (-0.306±0.144, - 0.290±0.116, -0.283±0.048, -0.288±0.057), BCR-1 (-0.399±0.079, -0.346±0.046), AGV-1 (-0.295±0.110, -0.307±0.086, -0.339±0.068), BHVO-1 (-0.308±0.076, - 0.299±0.103), and DTS-1 (-0.299±0.163, -0.368±0.059). δ26MgDSM-3 of measured USGS standards are consistent within error (2σ).

  4. Resetting of Mg isotopes between calcite and dolomite during burial metamorphism: Outlook of Mg isotopes as geothermometer and seawater proxy

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    Hu, Zhongya; Hu, Wenxuan; Wang, Xiaomin; Lu, Yizhou; Wang, Lichao; Liao, Zhiwei; Li, Weiqiang

    2017-07-01

    Magnesium isotopes are an emerging tool to study the geological processes recorded in carbonates. Calcite, due to its ubiquitous occurrence and the large Mg isotope fractionation associated with the mineral, has attracted great interests in applications of Mg isotope geochemistry. However, the fidelity of Mg isotopes in geological records of carbonate minerals (e.g., calcite and dolomite) against burial metamorphism remains poorly constrained. Here we report our investigation on the Mg isotope systematics of a dolomitized Middle Triassic Geshan carbonate section in eastern China. Magnesium isotope analysis was complemented by analyses of Sr-C-O isotopic compositions, major and trace element concentrations, and petrographic and mineralogical features. Multiple lines of evidence consistently indicated that post-depositional diagenesis of carbonate minerals occurred to the carbonate rocks. Magnesium isotope compositions of the carbonate rocks closely follow a mixing trend between a high δ26Mg dolomite end member and a low δ26Mg calcite end member, irrespective of sample positions in the section and calcite/dolomite ratio in the samples. By fitting the measured Mg isotope data using a two-end member mixing model, an inter-mineral Δ26Mgdolomite-calcite fractionation of 0.72‰ was obtained. Based on the experimentally derived Mg isotope fractionation factors for dolomite and calcite, a temperature of 150-190 °C was calculated to correspond to the 0.72‰ Δ26Mgdolomite-calcite fractionation. Such temperature range matches with the burial-thermal history of the local strata, making a successful case of Mg isotope geothermometry. Our results indicate that both calcite and dolomite had been re-equilibrated during burial metamorphism, and based on isotope mass balance of Mg, the system was buffered by dolomite in the section. Therefore, burial metamorphism may reset Mg isotope signature of calcite, and Mg isotope compositions in calcite should be dealt with caution in

  5. Experimental calibration of Mg isotope fractionation between aragonite and seawater

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    Wang, Zhengrong; Hu, Ping; Gaetani, Glenn; Liu, Chao; Saenger, Casey; Cohen, Anne; Hart, Stanley

    2013-02-01

    The detectable magnesium (Mg) isotope fractionation between biogenic aragonite (including aragonitic corals, bivalves, scaphopod, and sclerosponges) and seawater can potentially be applied to reconstruct sea surface temperature (SST) in the past. To calibrate this thermometer, eight sets of inorganic precipitation experiments ('free-drift') in seawater (Mg/Ca = 5 or 10) have been carried out at 25-55 °C over a range of degassing rate. A cleaning procedure was adopted to remove Mg contamination by sea salt, surface absorbed Mg and silicate dust as nucleation centers. The Mg isotope fractionation between cleaned aragonite and seawater-like aqueous solution varies insignificantly with Mg/Ca ratios and Mg isotope compositions of the initial solution, and the CO2-degassing rate (0-75 cc/min), but decreases noticeably with increasing temperatures having a temperature sensitivity of ˜0.008-0.01‰/°C in the following form: Δ≈1000lnα=1.67(±0.36)-0.82(±0.11)×{1000}/{T} where αaragonite-seawater is the fractionation factor, and T is the absolute temperature in Kelvin. It is consistent with equilibrium fractionation between Mg2+ aquo-complex and magnesite predicted by one theoretical calculation. Qualitative comparison among Mg-bearing carbonates based on Mg-O bond strengths show the relative sequence of 26Mg enrichment is aragonite > dolomite > magnesite > calcite. Thus, the surprising agreement indicates either the calculation overestimated Mg fractionation between magnesite and fluid, or both theoretical calculation and our calibration represent Mg isotope fractionation between MgCO30-H2O cluster and Mg2+ aquo complexes. Comparison of our calibration with the Mg isotope fractionation between biogenic aragonite and seawater suggests Mg and oxygen isotope fractionations of some biogenic aragonites (e.g., Porites sp. corals) agree with our calibration within analytical uncertainty, whereas others deviate significantly, indicating biological and/or kinetic isotope

  6. Magnesium isotope fractionation between brucite [Mg(OH)2] and Mg aqueous species: Implications for silicate weathering and biogeochemical processes

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    Li, Weiqiang; Beard, Brian L.; Li, Chengxiang; Johnson, Clark M.

    2014-05-01

    Brucite, with its octahedral structure, has a lattice configuration that is similar to the Mg-bearing octahedral layers in phyllosilicates. Understanding stable Mg isotope fractionation between brucite and aqueous solution therefore bears on interpretation of Mg isotope data in natural weathering systems. In this study, we experimentally determined Mg isotope fractionation between brucite and two Mg aqueous species, the free Mg aquo ion ([Mg(OH2)6]2+) and EDTA-bonded Mg (Mg-EDTA2-). Results from recrystallization and brucite synthesis experiments suggest mild preferential partitioning of light Mg isotopes into brucite compared to Mg aquo ions at low temperatures, where measured ΔMgbrucite-Mg26 fractionation increased from ca. -0.3‰ at 7 °C, to ca. -0.2‰ at 22 °C, to ca. 0‰ at 40 °C. MgO hydrolysis experiments in EDTA-bearing solutions suggest that the ΔMgbrucite-Mg-EDTA26 fractionation is ⩾+2.0‰ at 22 °C, indicating that light Mg isotopes strongly partition into Mg-EDTA complex relative to brucite, as well as relative to Mg aquo ions. Magnesium atoms in brucite, Mg aquo ions, and Mg-EDTA complexes are all octahedrally coordinated, and the measured Mg isotope fractionations correlate with average bond lengths for Mg. Aqueous Mg ions have the shortest bond length among the three phases, and enrich heavy Mg isotopes relative to brucite and Mg-EDTA. In contrast, Mg-EDTA has the longest average bond length for Mg, and enriches light Mg isotopes relative to Mg aquo ions and brucite; the relatively long Mg-EDTA bond suggests that organically bound Mg may commonly have low 26Mg/24Mg ratios, which may explain proposed "vital" effects for stable Mg isotopes. Such relations between bond length and Mg isotope fractionation could be extended to other phyllosilicates such as serpentine- and clay-group minerals where Mg is also octahedrally coordinated.

  7. The magnesium isotope (δ26Mg) signature of dolomites

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    Geske, A.; Goldstein, R. H.; Mavromatis, V.; Richter, D. K.; Buhl, D.; Kluge, T.; John, C. M.; Immenhauser, A.

    2015-01-01

    Dolomite precipitation models and kinetics are debated and complicated due to the complex and temporally fluctuating fluid chemistry and different diagenetic environments. Using well-established isotope systems (δ18O, δ13C, 87Sr/86Sr), fluid inclusions and elemental data, as well as a detailed sedimentological and petrographic data set, we established the precipitation environment and subsequent diagenetic pathways of a series of Proterozoic to Pleistocene syn-depositional marine evaporative (sabkha) dolomites, syn-depositional non-marine evaporative (lacustrine and palustrine) dolomites, altered marine ("mixing zone") dolomites and late diagenetic hydrothermal dolomites. These data form the prerequisite for a systematic investigation of dolomite magnesium isotope ratios (δ26Mgdol). Dolomite δ26Mg ratios documented here range, from -2.49‰ to -0.45‰ (δ26Mgmean = -1.75 ± 1.08‰, n = 42). The isotopically most depleted end member is represented by earliest diagenetic marine evaporative sabkha dolomites (-2.11 ± 0.54‰ 2σ, n = 14). In comparing ancient compositions to modern ones, some of the variation is probably due to alteration. Altered marine (-1.41 ± 0.64‰ 2σ, n = 4), and earliest diagenetic lacustrine and palustrine dolomites (-1.25 ± 0.86‰ 2σ, n = 14) are less negative than sabkha dolomites but not distinct in composition. Various hydrothermal dolomites are characterized by a comparatively wide range of δ26Mg ratios, with values of -1.44 ± 1.33‰ (2σ, n = 10). By using fluid inclusion data and clumped isotope thermometry (Δ47) to represent temperature of precipitation for hydrothermal dolomites, there is no correlation between fluid temperature (∼100 to 180 °C) and dolomite Mg isotope signature (R2 = 0.14); nor is there a correlation between δ26Mgdol and δ18Odol. Magnesium-isotope values of different dolomite types are affected by a complex array of different Mg sources and sinks, dissolution/precipitation and non

  8. Impact of amorphous precursor phases on magnesium isotope signatures of Mg-calcite

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    Mavromatis, Vasileios; Purgstaller, Bettina; Dietzel, Martin; Buhl, Dieter; Immenhauser, Adrian; Schott, Jacques

    2017-04-01

    Various marine calcifiers form exoskeletons via an amorphous calcium carbonate (ACC) precursor phase and magnesium plays an important role in the temporary stabilization of this metastable phase. Thus, the use of Mg isotope ratios of marine biogenic carbonates as a proxy to reconstruct past seawater chemistry calls for a detailed understanding of the mechanisms controlling Mg isotope signatures during the formation and transformation of ACC to the final crystalline carbonate mineral. For this purpose we have investigated the Mg isotope fractionation between (Ca,Mg)CO3 solids and aqueous fluids at 25 °C and pH = 8.3 during (i) the direct precipitation of crystalline Mg-calcite and (ii) the formation of Mg-rich ACC (Mg-ACC) and its transformation to Mg-calcite. The outcome documents that the small Mg isotope fractionation between Mg-ACC and reactive fluid (ΔMg26ACC-fluid = - 1.0 ± 0.1 ‰) is not preserved during the transformation of the ACCs into Mg-calcite. Following a pronounced isotopic shift accompanying the transformation of Mg-ACC into Mg-calcite, Δ26Mgcalcite-fluid progressively decreases with reaction progress from ∼ - 3.0 ‰ to - 3.6 ‰, reflecting both the approach of isotopic equilibrium and the increase of calcite Mg content (to near 20 mol % Mg). In contrast the crystalline Mg-calcite precipitated directly from the reacting fluid, i.e. lacking a discernable formation of an amorphous precursor, exhibits only small temporal variations in Δ26Mgcalcite-fluid which overall is affected by the precipitation kinetics. The values found in this study at the onset of Mg-ACC precipitation for Mg isotope fractionation between Mg-ACC and the fluid (ΔMg26ACC-fluid = - 1.0 ‰) and between Mg-ACC and Mg2+(aq) (Δ (aq) 26Mg ACC-Mg2+ = + 2.0 ‰) are consistent with the formation of a hydrated Ca nanoporous solid accommodating Mg bicarbonate/carbonate species in combination with hydrated magnesium. This material crossed by percolating channels filled with the

  9. Textural and isotopic evidence for Ca-Mg carbonate pedogenesis

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    Diaz-Hernandez, J. L.; Sánchez-Navas, A.; Delgado, A.; Yepes, J.; Garcia-Casco, A.

    2018-02-01

    Models for evaluating the terrestrial carbon cycle must take into account not only soil organic carbon, represented by a mixture of plant and animal remains, but also soil inorganic carbon, contained in minerals, mainly in calcite and dolomite. Thick soil caliches derived from weathering of mafic and ultramafic rocks must be considered as sinks for carbon storage in soils. The formation of calcite and dolomite from pedogenic alteration of volcanic tephras under an aridic moisture regime is studied in an unusually thick 3-m soil profile on Gran Canaria island (Canary Islands, Spain). The biological activity of the pedogenic environment (soil respiration) releases CO2 incorporated as dissolved inorganic carbon (DIC) in waters. It drives the formation of low-magnesian calcite and calcian dolomite over basaltic substrates, with a δ13C negative signature (-8 to -6‰ vs. V-PDB). Precipitation of authigenic carbonates in the soil is accompanied by the formation of Mg-rich clay minerals and quartz after the weathering of basalts. Mineralogical, textural, compositional, and isotopic variations throughout the soil profile studied indicate that dolomite formed at greater depths and earlier than the calcite. The isotopic signatures of the surficial calcite and deeper dolomite crusts are primary and resulted from the dissolution-precipitation cycles that led to the formation of both types of caliches under different physicochemical conditions. Dolomite formed within a clay-rich matrix through diffusive transport of reactants. It is precipitated from water with more negative δ18O values (-1.5 to -3.5‰ vs. V-SMOW) in the subsoil compared to those of water in equilibrium with surficial calcite. Thus, calcite precipitated after dolomite, and directly from percolating solutions in equilibrium with vadose water enriched in δ18O (-0.5 to +1.5‰) due to the evaporation processes. The accumulation of inorganic carbon reaches 586.1 kg m-2 in the soil studied, which means that the

  10. Investigating the behaviour of Mg isotopes during the formation of clay minerals

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    Wimpenny, Joshua; Colla, Christopher A.; Yin, Qing-Zhu; Rustad, James R.; Casey, William H.

    2014-03-01

    We present elemental and isotopic data detailing how the Mg isotope system behaves in natural and experimentally synthesized clay minerals. We show that the bulk Mg isotopic composition (δ26Mg) of a set of natural illite, montmorillonite and kaolinite spans a 2‰ range, and that their isotopic composition depends strongly on a balance between the relative proportions of structural and exchangeable Mg. After acid leaching, these natural clays become relatively enriched in isotopically heavy Mg by between 0.2‰ and 1.6‰. Results of exchange experiments indicate that the Mg that has adsorbed to interlayer spaces and surface charged sites is relatively enriched in isotopically light Mg compared to the residual clay. The isotopic composition of this exchangeable Mg (-1.49‰ to -2.03‰) is characteristic of the isotopic composition of Mg found in many natural waters. Further experiments with an isotopically characterized MgCl2 solution shows that the clay minerals adsorb this exchangeable Mg with little or no isotopic fractionation, although we cannot discount the possibility that the uptake of exchangeable Mg does so with a slight preference for 24Mg. To characterize the behaviour of Mg isotopes during clay mineral formation we synthesized brucite (Mg(OH)2), which we consider to be a good analogue for the incorporation of Mg into the octahedral sheet of Mg-rich clay minerals or into the brucitic layer of clays such as chlorite. In our experiment the brucite mineral becomes enriched in the heavy isotopes of Mg while the corresponding solution is always relatively enriched in isotopically light Mg. The system reaches a steady state after 10 days with a final fractionation factor (αsolid-solution) of 1.0005 at near-neutral pH. This result is consistent with the general consensus that secondary clay minerals preferentially take up isotopically heavy Mg during their formation. However our results also show that exchangeable Mg is an important component within bulk

  11. Mg isotope fractionation in biogenic carbonates of deep-sea coral, benthic foraminifera, and hermatypic coral.

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    Yoshimura, Toshihiro; Tanimizu, Masaharu; Inoue, Mayuri; Suzuki, Atsushi; Iwasaki, Nozomu; Kawahata, Hodaka

    2011-11-01

    High-precision Mg isotope measurements by multiple collector inductively coupled plasma mass spectrometry were applied for determinations of magnesium isotopic fractionation of biogenic calcium carbonates from seawater with a rapid Mg purification technique. The mean δ(26)Mg values of scleractinian corals, giant clam, benthic foraminifera, and calcite deep-sea corals were -0.87‰, -2.57‰, -2.34‰, and -2.43‰, suggesting preferential precipitation of light Mg isotopes to produce carbonate skeleton in biomineralization. Mg isotope fractionation in deep-sea coral, which has high Mg calcite skeleton, showed a clear temperature (T) dependence from 2.5 °C to 19.5 °C: 1,000 × ln(α) = -2.63 (±0.076) + 0.0138 (±0.0051) × T(R(2) = 0.82, p isotope fractionation may not be a major controlling factor for high-Mg calcite. The Mg isotope fractionation factors and the slope of temperature dependence from deep-sea corals and benthic foraminifera are similar to that for an inorganically precipitated calcite speleothem. Taking into account element partitioning and the calcification rate of biogenic CaCO(3), the similarity among inorganic minerals, deep-sea corals, and benthic foraminiferas may indicate a strong mineralogical control on Mg isotope fractionation for high-Mg calcite. On the other hand, δ(26)Mg in hermatypic corals composed of aragonite has been comparable with previous data on biogenic aragonite of coral, sclerosponges, and scaphopad, regardless of species differences of samples.

  12. Li isotopes in metal-poor halo dwarfs, a more and more complicated story

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    Spite, Monique; Spite, François

    2010-01-01

    International audience; The nuclei of the lithium isotopes are fragile, easily destroyed, so that, at variance with most of the other elements, they cannot be formed in stars through steady hydrostatic nucleosynthesis. The 7Li isotope is synthesized during primordial nucleosynthesis in the first minutes after the Big Bang and later by cosmic rays, by novae and in pulsations of AGB stars (possibly also by the "nu" process). 6Li is mainly formed by cosmic rays. The oldest (most metal-deficient)...

  13. Magnesium isotope fractionation in volcanic soils controlled by clay mineralogy and exchangeable Mg

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    Opfergelt, S.; Georg, B.; Burton, K.; Delvaux, B.; Siebert, C.; Guicharnaud, R.; Cabidoche, Y.; Halliday, A.

    2010-12-01

    Continental weathering of calcium-magnesium silicates exerts a strong control on atmospheric CO2 concentrations. Mg stable isotopes are used here as a biogeochemical tracer to quantify the contributions from soil weathering processes and vegetation on the Mg budget and the chemistry of soil solutions exported to the hydrosphere. We report the isotopic budget of Mg in distinct Mg pools (bedrock, vegetation, bulk soils, clay fractions, exchangeable Mg, soil pore waters) in tropical (Guadeloupe, Basse-Terre) and temperate volcanic soils (Iceland, Borgarfjordur catchment). Exchangeable Mg was collected by percolation of ammonium acetate 1N at pH7. Mg isotope ratios were measured by MC-ICP-MS (Nu Plasma HR) with an external reproducibility for DSM3 standard (Galy et al., 2003, JAAS 18, 1352-1356) of ± 0.15 ‰, 2SD, for δ26Mg. We investigated two soil sequences from Guadeloupe, both derived from andesitic ash, with the mineralogical sequence evolving towards Mg-bearing and non Mg-bearing secondary phases, respectively: (1) Andosol - Cambisol - Vertisol with the mineralogical sequence A - All - H,S - S (*), and (2) Andosol - Nitisol - Ferralsol with the sequence A - G,All - H,F - K,G,F. The basaltic soils from Iceland include Histosol and Histic, Gleyic and Brown Andosol with clay fractions mainly constituted of All, H and F. This selection of soils, with contrasting Mg-bearing and non-bearing secondary phases, and contrasting amount of Mg exchangeable (1.2 to 6.6 cmolc.kg-1), allows for a direct assessment of the weathering control on Mg isotope ratios and the Mg budget in both tropical and temperate conditions. In Guadeloupe, bulk soils and clay fractions were isotopically heavier (-0.41 to -0.10 ‰) than the andesite bedrock (-0.47 ‰). Icelandic bulk soils were isotopically similar or lighter (-0.80 to -0.25 ‰) than the parental basalt (-0.31 ‰). In both Guadeloupe and Iceland, soils were isotopically lighter with increasing amount of exchangeable Mg

  14. Al-Mg Isotope Study of Allende 5241

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    Kerekgyarto, A. G.; Jeffcoat, C. R.; Lapen, T. J.; Andreasen, R.; Righter, M.; Ross, D. K.; Simon, J. I.

    2016-01-01

    The defining characteristic of type B1 CAIs is a large (.5- 3mm) concentric melilite mantle [1]. In [2] we presented two isochrons from separate traverses across the melilite mantle of Allende EK 459-5-1. The primary petrographic differences between the traverses was the preservation of strong oscillatory zoning. The traverse that crossed the distinctive oscillatory zone produced a pristine internal isochron, while the other that did not have a strongly preserved oscillatory zone produced a disturbed isochron indicated by more scatter (higher MSWD) and a positive (delta)26Mg* intercept. The implication simply being that the oscillatory zone may represent varying conditions during the mantle formation event. We targeted a similar texture in Allende 5241 using the same methodology in an attempt to achieve similar results.

  15. Mg isotopes in biocarbonates: new insight into vital effects associated to echinoderms and bivalves calcification

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    Planchon, F.; Hermans, J.; Borremans, C.; Dubois, P.; Poulain, C.; Paulet, Y.; Andre, L.

    2007-12-01

    Mg isotopes can be helpful tracers to reveal the fundamental pathways of Mg incorporation during biomineralisation. We report in this study a detailed characterisation of the Mg isotopic signatures of different biominerals: high magnesium calcitic skeletons of selected echinoderms (sea urchins and starfish) and low magnesium aragonitic shells of a bivalve species (clam). State of the art analytical procedures were applied including sample purification step followed by high precision measurements using MC-ICP-MS (Nu instrument) in dry plasma conditions. 26Mg/24Mg and 25Mg/24Mg are expressed as per mil deviations from the DSM3 (Dead Sea Metal 3) reference standard in delta notation (d26Mg and d25Mg). For echinoderms, we considered: (a) adult specimens of six starfish species (Asteria r., Marthasterias g., Anseropoda p., Asterina g., Echinaster s. and Henricia o.), sampled in Brittany (France); (b) a sea urchin species (Paracentrotus lividus) with field samples (Mediterranean Sea, Marseille, France) and culture specimen under T and S controlled conditions. In vivo endoskeletons display negative, but different d26Mg values of -3.06 for starfish (with uniform interspecies signatures) and -2.65 for sea urchin. Relative to seawater signature (-0.82), all echinoderms favour the incorporation of light isotopes during biocalcification. The d26Mg depletion is lower than theoretically expected from a inorganic calcite precipitation from seawater (at -3.5). These differences suggest that on its route from seawater to the shell, Mg isotopes are partly biologically fractionationated through "vital effects" leaving heavier Mg isotopic signatures. Taken into account that calcification in echinoderms is an intra- cellular process involving transient amorphous calcium carbonate (ACC) phase, the observed bio-fractionation factors can be related to: (1) changes in the isotopic composition of the precipitating intracellular fluids due to active pumping in and out of the cell; (2) a

  16. Core correlation effects in multiconfiguration calculations of isotope shifts in Mg I

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    Filippin, Livio; Ekman, Jörgen; Jönsson, Per

    2016-01-01

    The present work reports results from systematic multiconfiguration Dirac-Hartree-Fock calculations of isotope shifts for several well-known transitions in neutral magnesium. Relativistic normal and specific mass shift factors as well as the electronic probability density at the origin are calculated. Combining these electronic quantities with available nuclear data, energy and transition level shifts are determined for the $^{26}$Mg$-^{24}$Mg pair of isotopes. Different models for electron correlation are adopted. It is shown that although valence and core-valence models provide accurate values for the isotope shifts, the inclusion of core-core excitations in the computational strategy significantly improves the accuracy of the transition energies and normal mass shift factors.

  17. Speleothem Mg-isotope time-series data from different climate belts

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    Riechelmann, S.; Buhl, D.; Richter, D. K.; Schröder-Ritzrau, A.; Riechelmann, D. F. C.; Niedermayr, A.; Vonhof, H. B.; Wassenburg, J.; Immenhauser, A.

    2012-04-01

    Speleothem Mg-isotope time-series data from different climate belts Sylvia Riechelmann (1), Dieter Buhl(1), Detlev K. Richter (1), Andrea Schröder-Ritzrau (2), Dana F.C. Riechelmann (3), Andrea Niedermayr (1), Hubert B. Vonhof (4) , Jasper Wassenburg (1), Adrian Immenhauser (1) (1) Ruhr-University Bochum, Institute for Geology, Mineralogy and Geophysics, Universitätsstraße 150, D-44801 Bochum, Germany (2) Heidelberg Academy of Sciences, Im Neuenheimer Feld 229, D-69120 Heidelberg, Germany (3) Johannes Gutenberg-University Mainz, Institute of Geography, Johann-Joachim-Becher-Weg 21, D-55128 Mainz, Germany (4) Faculty of Earth and Life Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV, Amsterdam, The Netherlands The Magnesium isotope proxy in Earth surface research is still underexplored. Recently, field and laboratory experiments have shed light on the complex suite of processes affecting Mg isotope fractionation in continental weathering systems. Magnesium-isotope fractionation in speleothems depends on a series of factors including biogenic activity and composition of soils, mineralogy of hostrock, changes in silicate versus carbonate weathering ratios, water residence time in the soil and hostrock and disequilibrium factors such as the precipitation rate of calcite in speleothems. Furthermore, the silicate (here mainly Mg-bearing clays) versus carbonate weathering ratio depends on air temperature and rainfall amount, also influencing the soil biogenic activity. It must be emphasized that carbonate weathering is generally dominant, but under increasingly warm and more arid climate conditions, silicate weathering rates increase and release 26Mg-enriched isotopes to the soil water. Furthermore, as shown in laboratory experiments, increasing calcite precipitation rates lead to elevated delta26Mg ratios and vice versa. Here, data from six stalagmite time-series Mg-isotope records (Thermo Fisher Scientific Neptune MC-ICP-MS) are shown. Stalagmites

  18. Crystallization history of enriched shergottites from Fe and Mg isotope fractionation in olivine megacrysts

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    Collinet, Max; Charlier, Bernard; Namur, Olivier; Oeser, Martin; Médard, Etienne; Weyer, Stefan

    2017-06-01

    Martian meteorites are the only samples available from the surface of Mars. Among them, olivine-phyric shergottites are basalts containing large zoned olivine crystals with highly magnesian cores (Fo 70-85) and rims richer in Fe (Fo 45-60). The Northwest Africa 1068 meteorite is one of the most primitive ;enriched; shergottites (high initial 87Sr/86Sr and low initial ε143Nd). It contains olivine crystals as magnesian as Fo 77 and is a major source of information to constrain the composition of the parental melt, the composition and depth of the mantle source, and the cooling and crystallization history of one of the younger magmatic events on Mars (∼180 Ma). In this study, Fe-Mg isotope profiles analyzed in situ by femtosecond-laser ablation MC-ICP-MS are combined with compositional profiles of major and trace elements in olivine megacrysts. The cores of olivine megacrysts are enriched in light Fe isotopes (δ56FeIRMM-14 = -0.6 to -0.9‰) and heavy Mg isotopes (δ26MgDSM-3 = 0-0.2‰) relative to megacryst rims and to the bulk martian isotopic composition (δ56Fe = 0 ± 0.05‰, δ26Mg = -0.27 ± 0.04‰). The flat forsterite profiles of megacryst cores associated with anti-correlated fractionation of Fe-Mg isotopes indicate that these elements have been rehomogenized by diffusion at high temperature. We present a 1-D model of simultaneous diffusion and crystal growth that reproduces the observed element and isotope profiles. The simulation results suggest that the cooling rate during megacryst core crystallization was slow (43 ± 21 °C/year), and consistent with pooling in a deep crustal magma chamber. The megacryst rims then crystallized 1-2 orders of magnitude faster during magma transport toward the shallower site of final emplacement. Megacryst cores had a forsterite content 3.2 ± 1.5 mol% higher than their current composition and some were in equilibrium with the whole-rock composition of NWA 1068 (Fo 80 ± 1.5). NWA 1068 composition is thus close to a

  19. Elucidating the controls on the Mg isotopic composition of marine pore fluids

    Science.gov (United States)

    Chanda, P.; Fantle, M.

    2013-12-01

    The Sr and Mg isotopic composition of pore fluids and carbonates from the Neogene section of Ocean Drilling Project Site 806B are reported (87Sr/86Sr and δ26Mg, measured using a Thermo Scientific Neptune Plus multi-collector ICP-MS). Site 806B, located on the northern margin of the Ontong Java Plateau, hosts a thick (776 m cored, depth to basement ~ 1200 m), relatively continuous, carbonate-rich section (between 83 and 96% CaCO3). Our goal in the current study is to use the Sr and Mg isotope data of pore fluids and carbonates to address open questions regarding (1) the extent to which the pore fluid chemistry is overprinted by calcite recrystallization, (2) the effects of diagenesis on bulk carbonate chemistry, and (3) the likelihood of preserving secular seawater δ26Mg trends in pore fluids. Accordingly, the current study compares and contrasts the isotopic and elemental data between adjacent ODP Sites 806B and 807A, which have similar depositional histories, carbonate contents, and pore fluid chemistries. The measured 87Sr/86Sr ratios of pore fluids at 806B range smoothly from 0.70914 at 4.45 mbsf to 0.70851 at 509.3 mbsf, similar (though offset relative) to the bulk carbonate trend (0.70918 to 0.70877 between 1.11 and 501.94 mbsf). The δ26MgDSM3 of 806B pore fluids generally increases from -0.86‰ at 4.45 mbsf to -0.17‰ at 679.0 mbsf. The overall trend is consistent with previously collected δ26Mg data at 807A [1]; there is, however, a significant difference in pore fluid δ26Mg between the two sites at depths of 300 to 600 mbsf. At these depths, 806B pore fluid δ26Mg values are +0.2 to 0.3‰ relative to 807A at similar depths [1]. The application of a depositional reactive transport model to the Sr isotope data suggests that bulk carbonate recrystallization rates at 806B are similar to those at 807A (histories of the sedimentary column (the latter is suggested by the differences in δ26Mg trends at depth). Preliminary model results suggest that

  20. Isotopic Fractionation of Mg2+(aq), Ca2+(aq), and Fe2+(aq) with Carbonate Minerals

    Energy Technology Data Exchange (ETDEWEB)

    Rustad, James R.; Casey, William H.; Yin, Qing-Zhu; Bylaska, Eric J.; Felmy, Andrew R.; Bogatko, Stuart A.; Jackson, Virgil E.; Dixon, David A.

    2010-11-15

    Density functional electronic structure calculations are used to compute the equilibrium constant (the isotope fractionation factor) for 26Mg/24Mg and 44Ca/40Ca isotope exchange between carbonate minerals and uncomplexed divalent aquo ions. The most reliable calculations at the B3LYP/6-311++G(2d,2p) level predict equilibrium constants K, reported as 103ln(K) at 25 °C, of -5.3, -1.1, and +1.1 for 26Mg/24Mg exchange between calcite (CaCO3), magnesite (MgCO3), and dolomite (Ca0.5Mg0.5CO3), respectively, and Mg2+(aq), with positive values indicating enrichment in the mineral phase. For 44Ca/40Ca exchange between calcite and Ca2+(aq), the calculations predict values of +1.5 for Ca2+(aq) in six-fold coordination and +4.1 for Ca2+(aq) in seven-fold coordination. We find that the reduced partition function ratios can be reliably computed from systems as small as M(CO3)610- and M2+(H2O)6 embedded in a set of fixed atoms representing the 2nd shell (and greater) coordination environment. We find that the aqueous cluster representing the aquo ion is much more sensitive to improvements in the basis set than the calculations on the mineral systems, and that fractionation factors should be computed using 2 the best possible basis set for the aquo complex, even if the reduced partition function ratio calculated with the same basis set is not available for the mineral system. The new calculations show that the previous discrepancies between theory and experiment for Fe3+-hematite and Fe2+-siderite fractionations arise from an insufficiently accurate reduced partition function ratio for the Fe3+(aq) and Fe2+(aq) species.

  1. Isotopic fractionation of Mg 2+(aq), Ca 2+(aq), and Fe 2+(aq) with carbonate minerals

    Science.gov (United States)

    Rustad, James R.; Casey, William H.; Yin, Qing-Zhu; Bylaska, Eric J.; Felmy, Andrew R.; Bogatko, Stuart A.; Jackson, Virgil E.; Dixon, David A.

    2010-11-01

    Density-functional electronic structure calculations are used to compute the equilibrium constants for 26Mg/ 24Mg and 44Ca/ 40Ca isotope exchange between carbonate minerals and uncomplexed divalent aquo ions. The most reliable calculations at the B3LYP/6-311++G(2d,2p) level predict equilibrium constants K, reported as 10 3ln ( K) at 25 °C, of -5.3, -1.1, and +1.2 for 26Mg/ 24Mg exchange between calcite (CaCO 3), magnesite (MgCO 3), and dolomite (Ca 0.5Mg 0.5CO 3), respectively, and Mg 2+(aq), with positive values indicating enrichment of the heavy isotope in the mineral phase. For 44Ca/ 40Ca exchange between calcite and Ca 2+(aq) at 25 °C, the calculations predict values of +1.5 for Ca 2+(aq) in 6-fold coordination and +4.1 for Ca 2+(aq) in 7-fold coordination. We find that the reduced partition function ratios can be reliably computed from systems as small as M(CO)610- and M(HO)62+ embedded in a set of fixed atoms representing the second-shell (and greater) coordination environment. We find that the aqueous cluster representing the aquo ion is much more sensitive to improvements in the basis set than the calculations on the mineral systems, and that fractionation factors should be computed using the best possible basis set for the aquo complex, even if the reduced partition function ratio calculated with the same basis set is not available for the mineral system. The new calculations show that the previous discrepancies between theory and experiment for Fe 3+-hematite and Fe 2+-siderite fractionations arise from an insufficiently accurate reduced partition function ratio for the Fe 3+(aq) and Fe 2+(aq) species.

  2. Evolution of Single Particle and Collective properties in the Neutron-Rich Mg Isotopes

    CERN Multimedia

    Reiter, P; Wiens, A; Fitting, J; Lauer, M; Van duppen, P L E; Finke, F

    2002-01-01

    We propose to study the single particle and collective properties of the neutron-rich Mg isotopes in transfer reactions and Coulomb excitation using REX-ISOLDE and MINIBALL. From the Coulomb excitation measurement precise and largely model independent B( E2 ; 0$^{+}_{g.s.}\\rightarrow$ 2$^{+}_{1}$ ) will be determined for the even-even isotopes. For the odd isotopes the distribution of the E2 strength over a few low-lying states will be measured. The sign of the M1/E2 mixing ratio, extracted from angular distributions, is characteristic of the sign of the deformation, as is the resulting level scheme. The neutron-pickup channel in the transfer reactions will allow for a determination of the single particle properties (spin, parity, spectroscopic factors) of these nuclei. This information will give new insights in changes of nuclear structure in the vicinity of the island of deformation around $^{32}$Mg. A total of 24 shifts of REX beam time is requested.

  3. The nucleosynthesis of heavy elements in Stars: the key isotope 25Mg

    Directory of Open Access Journals (Sweden)

    Massimi C.

    2014-03-01

    Full Text Available We have measured the radiative neutron-capture cross section and the total neutron-induced cross section of one of the most important isotopes for the s process, the 25Mg. The measurements have been carried out at the neutron time-of-flight facilities n_TOF at CERN (Switzerland and GELINA installed at the EC-JRC-IRMM (Belgium. The cross sections as a function of neutron energy have been measured up to approximately 300 keV, covering the energy region of interest to the s process. The data analysis is ongoing and preliminary results show the potential relevance for the s process.

  4. High-precision Mg isotope measurements of terrestrial and extraterrestrial material by HR-MC-ICPMS—implications for the relative and absolute Mg isotope composition of the bulk silicate Earth

    DEFF Research Database (Denmark)

    Bizzarro, Martin; Paton, Chad; Larsen, Kirsten Kolbjørn

    2011-01-01

    We report novel methods for the chemical purification of Mg from silicate rocks by ion-exchange chromatography, and high-precision analysis of Mg-isotopes by high-resolution multiple collector inductively coupled plasma source mass spectrometry (HR-MC-ICPMS). Using these methods, we have measured...... the data obtained by the relative and absolute methods, we propose that these new values represent the absolute Mg-isotope composition of the bulk inner solar system. Using the absolute Mg-isotope composition of the J12 olivine, we calculate the isotopic abundances of Mg as 24Mg 1/4 0.789548 ¿ 0.000026, 25......Mg 1/4 0.100190 ¿ 0.000018, and 26Mg 1/4 0.110261 ¿ 0.000023. Based on this result, we have calculated an atomic weight for Mg of 24.305565 ¿ 0.000045, which is marginally heavier than previous estimates but a factor of 10 more precise....

  5. Doping-Induced Isotopic Mg11B2 Bulk Superconductor for Fusion Application

    Directory of Open Access Journals (Sweden)

    Qi Cai

    2017-03-01

    Full Text Available Superconducting wires are widely used for fabricating magnetic coils in fusion reactors. Superconducting magnet system represents a key determinant of the thermal efficiency and the construction/operating costs of such a reactor. In consideration of the stability of 11B against fast neutron irradiation and its lower induced radioactivation properties, MgB2 superconductor with 11B serving as the boron source is an alternative candidate for use in fusion reactors with a severe high neutron flux environment. In the present work, the glycine-doped Mg11B2 bulk superconductor was synthesized from isotopic 11B powder to enhance the high field properties. The critical current density was enhanced (103 A·cm−2 at 20 K and 5 T over the entire field in contrast with the sample prepared from natural boron.

  6. Photodissociation spectroscopy of the Mg + -CO2 complex and its isotopic analogs

    Science.gov (United States)

    Yeh, C. S.; Willey, K. F.; Robbins, D. L.; Pilgrim, J. S.; Duncan, M. A.

    1993-02-01

    Mg+-CO2 ion-molecule cluster complexes are produced by laser vaporization in a pulsed nozzle cluster source. The vibronic spectroscopy in these complexes is studied with mass-selected photodissociation spectroscopy in a reflectron time-of-flight mass spectrometer. Two excited electronic states are observed (2) 2Σ+ and 2Π. The 2Π state has a vibrational progression in the metal-CO2 stretching mode (ωe'=381.8 cm-1). The complexes are linear (Mg+-OCO) and are bound by the charge-quadrupole interaction. The dissociation energy (D0`) is 14.7 kcal/mol. Corresponding spectra are measured for each of the 24, 25, and 26 isotopes of magnesium. These results are compared to theoretical predictions made by Bauschlicher and co-workers.

  7. Quantifying the effect of diagenetic recrystallization on the Mg isotopic composition of marine carbonates

    Science.gov (United States)

    Chanda, Piyali; Fantle, Matthew S.

    2017-05-01

    The Mg and Sr isotopic compositions (δ26Mg and 87Sr/86Sr) of pore fluids and bulk carbonates from Ocean Drilling Project Site 1171 (South Tasman Rise; 2148.2 m water depth) are reported, in order to evaluate the potential of diagenesis to alter carbonate-based geochemical proxies in an open marine system. Given the trace amounts of Mg in marine carbonates relative to coexisting pore fluids, diagenesis can alter carbonate δ26Mg, a promising proxy for seawater δ26Mg that may help elucidate long-term changes in the global Mg cycle. Constraints on the effect of diagenetic recrystallization on carbonate δ26Mg are therefore critical for accurate proxy interpretations. This study provides context for assessing the fidelity of geochemical proxy-reconstructions using the primary components (i.e., foraminiferal tests and nannofossils) of bulk carbonate sediments. We find that pore fluid δ26Mg values (on the DSM3 scale) at Site 1171 increase systematically with depth (from -0.72‰ to -0.39‰ in the upper ∼260 m), while the δ26Mg of bulk carbonates decrease systematically with depth (from -2.23‰ to -5.00‰ in the upper ∼260 m). This variability is ascribed primarily to carbonate recrystallization, with a small proportion of the variability due to down-hole changes in nannofossil and foraminiferal species composition. The inferred effect of diagenesis on bulk carbonate δ26Mg correlates with down-core changes in Mg/Ca, Sr/Ca, Na/Ca, and 87Sr/86Sr. A depositional reactive-transport model is employed to validate the hypothesis that calcite recrystallization in this system can generate sizeable shifts in carbonate δ26Mg. Model fits to the data suggest a fractionation factor and a partition coefficient that are consistent with previous work, assuming calcite recrystallization rates of ⩽7%/Ma constrained by Sr geochemistry. In addition, either partial dissolution or a distinctly different previous diagenetic regime must be invoked in order to explain aspects of the

  8. Artificial halos

    Science.gov (United States)

    Selmke, Markus

    2015-09-01

    Judged by their frequency and beauty, ice halos easily rival rainbows as a prominent atmospheric optics phenomenon. This article presents experimental halo demonstrations of varying complexity. Using a single commercially available hexagonal glass prism, a variety of artificial halos can be simulated. The experiments include laser beam path analysis, a modified classic spinning prism experiment, and a novel Monte-Carlo machine for three-dimensional rotations. Each of these experiments emulates different conditions of certain halo displays, and in combination, they allow a thorough understanding of these striking phenomena.

  9. Isotope composition of Cd, Ca and Mg in the Brownfield chondrite

    Energy Technology Data Exchange (ETDEWEB)

    Rosman, K.J.R.; Barnes, I.L.; Moore, L.J.; Gramlich, J.W. (National Bureau of Standards, Washington, DC (USA))

    1980-01-01

    The isotopic composition of cadmium, calcium and magnesium in the Brownfield chondrite have been measured. The measurements on cadmium show that this element is isotopically fractionated with the heavier isotopes relatively enriched to the extent of 0.27% per mass unit. This confirms earlier reports by ROSMAN and DE LAETER (1976, 1978). Calcium and magnesium show no evidence of isotope fractionation, indicating that the process responsible for fractionating cadmium dose not seem to have affected these more refractory elements.

  10. Concentration effect on equilibrium fractionation of Mg-Ca isotopes in carbonate minerals: Insights from first-principles calculations

    Science.gov (United States)

    Wang, Wenzhong; Qin, Tian; Zhou, Chen; Huang, Shichun; Wu, Zhongqing; Huang, Fang

    2017-07-01

    Naturally occurring carbonates have a wide variation in Mg and Ca contents. Using the density-functional-theory calculations, this study examines the effect of Mg and Ca concentrations on bond lengths and equilibrium fractionation factors of Mg-Ca isotopes among calcite-type carbonate minerals (MgxCa1-xCO3). Mg content x and Ca content (1-x) of the investigated carbonate minerals range from 1/12 to 1 and from 1/36 to 1, respectively. Concentration of Ca and Mg in carbonates have significant effects on Ca-O and Mg-O bond lengths when x is close to 0, 0.5 or 1. Because equilibrium isotope fractionation factors (103lnα) are mainly controlled by their relevant bond strengths, which can be measured using their average bond lengths, 103lnα of 26Mg/24Mg and 44Ca/40Ca between calcite-type carbonate minerals and dolomite also vary dramatically with Mg content, especially when x is close to 0 and 1. For instance, at 300 K, 103lnα of 26Mg/24Mg between Mg1/12Ca11/12CO3 and dolomite (x = 0.5) is ∼-4.3‰, while 103lnα of 44Ca/40Ca between Mg23/24Ca1/24CO3 and dolomite is ∼6‰. Dolomite is enriched in 26Mg but depleted in 44Ca relative to all other carbonate minerals, which is consistent with it having the shortest Mg-O bond length and the longest Ca-O bond lengths among all carbonates. At 300 K, a small change of x from 0.5 to 0.6 in dolomite could result in 1‰ variation in 103lnβ of 26Mg/24Mg. Therefore, the concentration effect in carbonate minerals should be taken into account when applying the isotope fractionation factors of carbonate minerals to understand geochemical processes.

  11. Equilibrium magnesium isotope fractionation between aqueous Mg2+ and carbonate minerals: Insights from path integral molecular dynamics

    Science.gov (United States)

    Pinilla, Carlos; Blanchard, Marc; Balan, Etienne; Natarajan, Suresh K.; Vuilleumier, Rodolphe; Mauri, Francesco

    2015-08-01

    The theoretical determination of the isotopic fractionation between an aqueous solution and a mineral is of utmost importance in Earth sciences. While for crystals, it is well established that equilibrium isotopic fractionation factors can be calculated using a statistical thermodynamic approach based on the vibrational properties, several theoretical methods are currently used to model ions in aqueous solution. In this work, we present a systematic study to determine the reduced partition function ratio (β-factor) of aqueous Mg2+ using several levels of theory within the simulations. In particular, using an empirical force field, we compare and discuss the performance of the exact results obtained from path integral molecular dynamics (PIMD) simulations, with respect to the more traditional methods based on vibrational properties and the cluster approximation. The results show the importance of including configurational disorder for the estimation of the equilibrium isotope fractionation factor. We also show that using the vibrational frequencies computed from snapshots taken from equilibrated classical molecular dynamics represents a good approximation for the study of aqueous ions. Based on these conclusions, the β-factor of aqueous Mg2+ have been estimated from a Car-Parrinello molecular dynamics (CPMD) simulation with an ab initio force field, and combined with the β-factors of carbonate minerals (magnesite, dolomite, calcite and aragonite). Mg β-factor of Mg-bearing aragonite, calculated here for the first time, displays a lower value than the three other carbonate minerals. This is explained by a strong distortion of the cationic site leading to a decrease of the coordination number during Ca-Mg substitution. Overall, the equilibrium magnesium isotope fractionation factors between aqueous Mg2+ and carbonate minerals that derive from this methodological study support the previous theoretical results obtained from embedded cluster models.

  12. Using a novel Mg isotope tracer to investigate the dolomitization of the Red River Formation in the Williston Basin

    Science.gov (United States)

    Kimmig, S. R.; Holmden, C. E.; Qing, H.

    2015-12-01

    The Williston Basin is a sub-circular intracratonic basin spanning central North America with its center in NW North Dakota. The Late Ordovician Red River Formation is an economically viable unit in the Williston Basin containing large hydrocarbon reserves in Saskatchewan, North Dakota, Manitoba, and Montana. Red River dolomitization contributed to the reservoir-quality porosity and permeability observed today with three types of dolomite (burrow, matrix, and saddle) possibly representing three events. Dolomitization is widely believed to have resulted from downward percolating brines, due to the stratigraphically close association between dolomite deposits and overlying basin-scale evaporites. However, in contrast, Sr isotope evidence suggests an upward fluid migration in the basin. Spatial variation of Mg isotopes (δ26Mg) may serve as a direct tracer of dolomitizing fluid flow. Dolomite sequesters light isotopes of Mg from dolomitizing fluids, therefore, the fluid will evolve with time and distance to heavier δ26Mg values. Accordingly, the δ26Mg values of the Red River dolomite should increase in the direction of fluid flow. We test this hypothesis on Red River burrow dolomite from the Williston Basin; the first event most often attributed to downward infiltration of brines. Burrow δ26Mg values range between -1.89‰ and -1.31‰. Using contouring software, the data are shown to form a pattern of increasing δ26Mg values out from the center of the Williston Basin, indicating an up-dip migration of dolomitizing fluids through the burrow network, rather than down-dip as suggested by the brine reflux model. We conclude that dolomitization of the Red River carbonate is not tied to the spatial and temporal history of evaporite deposition in the Williston Basin, but rather to the thermal history of the basin, suggesting dolomitization likely occurred during a late Paleozoic heating event that drove Mg-rich connate waters ponded in the center of the basin upwards

  13. Kinetics in the critical zone : insights from Mg & Sr isotopes in landslides

    Science.gov (United States)

    Galy, Albert; Emberson, Robert; Bedja, Imene; Hovius, Niels

    2017-04-01

    The critical zone is characterized by a wide range of characteristic time, from s to Myr. When the water/rock interaction is considered, the kinetic of the chemical reaction can be slow enough to become the driver of the geochemical imprint of the water (rather than the hydrological residence time). This led the idea that the changes in isotopic ratios in terrestrial surface waters should correspond to changes in the overall dissolution. When chemical elements or isotopic signatures are characteristic to one lithology, namely silicate, this implies that the silicate mineral phases that act as sources of a given isotope dissolve at a rate that is proportional to the overall silicate weathering. However, bedrock landsliding exhumes large quantities of fresh rock that get weathered in transient storage (the bottom of the landslide's scar), and rapid weathering in these deposits is controlled primarily by dissolution of the most reactive phases. In this study, we test the hypothesis that preferential weathering of labile minerals can decouple the dissolution of strontium and magnesium sources from the actual silicate weathering rates in the rapidly eroding Western Southern Alps (WSA) of New Zealand. We find that rapid dissolution of calcite enriched in radiogenic strontium during regional metamorphism and biotite (minerals always characterised by elevated 87Sr/86Sr) in landslides leads to high local fluxes in strontium with isotopic ratios that offer no clear discrimination between sources. These higher fluxes of radiogenic strontium are in contrast to silicate weathering rates in landslides that are not systematically elevated. On the contrary, the magnesium isotopes are barely affected by the preferential weathering of these 2 labile minerals. This could be related that biotite hosts the majority of the magnesium in the Alpine Schist and its dissolution buffer the isotopic signature. However the values are different from the signature of pure biotite. Magnesium

  14. Chemical and isotopic kinship of iron in the Earth and Moon deduced from the lunar Mg-Suite

    Science.gov (United States)

    Sossi, Paolo A.; Moynier, Frédéric

    2017-08-01

    The Moon and the Earth's mantle share many chemical and isotopic traits, leading to the prevailing theory that they were formed from similar material. Iron is one element that shows apparent differences between the two bodies, with models for the composition of the Moon having ≈1.5 times more FeO (12-14 wt.%), relative to the Earth's mantle (8 wt.%). This difference is mirrored in their isotope compositions, where lunar mare basalts have δ57Fe (per mille deviation of the 57Fe/54Fe ratio from the IRMM-014 standard) 0.1-0.2‰ higher than peridotitic rocks representative of Earth's mantle, a feature initially attributed to loss of isotopically light Fe following a giant impact. However, whether basaltic rocks are suitable analogues for the Moon's composition is debatable in the light of their distinct source regions that reflect the extensive lithological stratification of the lunar mantle. Here, we evaluate the iron isotope composition of the bulk Moon through the study of igneous cumulate rocks of the lunar highlands Magnesium Suite (Mg Suite). The δ57Fe of Mg Suite rocks spans a limited range, from 0.05‰ to 0.10‰, with an average (+ 0.07 ± 0.02 ‰) that overlaps with Earth's mantle (+ 0.05 ± 0.01 ‰), similarities that extend to their Mg#s, where both reach 0.9. Numerical modelling of iron isotope fractionation during lunar magma ocean crystallisation shows that the Mg Suite should accurately reflect the composition of the bulk Moon, which is therefore + 0.07 ± 0.02 ‰, indistinguishable from Earth's mantle but heavier than chondrites (- 0.01 ± 0.01 ‰). Iron thus behaves coherently with other elements that condense at temperatures higher than Li in showing no isotopic difference between the Earth and Moon, suggesting element depletion on the Moon affected only the more volatile elements. Therefore, there is no cosmochemical basis for iron enrichment or depletion in the bulk Moon relative to the Earth's mantle, whose composition is an analogue for

  15. Effect of interband interaction on isotope effect exponent of MgB2 ...

    Indian Academy of Sciences (India)

    com. MS received 22 September 2004; revised 5 January 2006; accepted 24 January 2005. Abstract. The exact formula of Tc's equation and the isotope effect exponent of two- band s-wave superconductors in the weak-coupling limit are ...

  16. Mg Isotope Fractionation during Uptake by a Rock-Inhabiting, Model Microcolonial Fungus Knufia petricola at Acidic and Neutral pH.

    Science.gov (United States)

    Pokharel, Rasesh; Gerrits, Ruben; Schuessler, Jan A; Floor, Geerke H; Gorbushina, Anna A; von Blanckenburg, Friedhelm

    2017-09-05

    The model rock-inhabiting microcolonial fungus Knufia petricola fractionates stable Mg isotopes in a time- and pH-dependent manner. During growth, the increase of 26Mg/24Mg in the fungal cells relative to the growth media amounted to 0.65 ± 0.14‰ at pH 6 and 1.11 ± 0.35‰ at pH 3. We suggest a constant equilibrium fractionation factor during incorporation of Mg into ribosomes and ATP as a cause of enrichment of 26Mg in the cells. We suggest too that the proton gradient across the cell wall and cytoplasmic membrane controls Mg2+ transport into the fungal cell. As the strength of this gradient is a function of extracellular solution pH, the pH-dependence on Mg isotope fractionation is thus due to differences in fungal cell mass fluxes. Through a mass balance model we show that Mg uptake into the fungal cell is not associated with a unique Mg isotope fractionation factor. This Mg isotope fractionation dependence on pH might also be observed in any organism with cells that follow similar Mg uptake and metabolic pathways and serves to reveal Mg cycling in ecosystems.

  17. High-precision 27Al/24Mg ratio determination using a modified isotope-dilution approach

    DEFF Research Database (Denmark)

    Paton, Chad; Schiller, Martin; Ulfbeck, David Garf

    2012-01-01

    The precision of the 26Al–26Mg system—one of the most widely used chronometers for constraining the relative timing of events in the early solar system—is presently limited by methods for the determination of 27Al/24Mg ratios, which have seen little improvement in the last decade. We present...... on multiple measurements of a ∼2.7 gram piece of the Ivuna CI chondrite, we present a new estimate for the 27Al/24Mg ratio of this meteorite of 0.09781 ± 0.00029....

  18. Evidence for a vanishing 6Li/7Li isotopic signature in the metal-poor halo star HD84937

    DEFF Research Database (Denmark)

    Lind, K.; Asplund, M.; Collet, Remo

    2012-01-01

    The claimed detections of 6Li in the atmospheres of some metal-poor halo stars have lead to speculative additions to the standard model of Big Bang nucleosynthesis and the early Universe, as the inferred abundances cannot be explained by Galactic cosmic ray production. A prominent example of a so...

  19. Borromean halo, Tango halo, and halo isomers in atomic nuclei

    Science.gov (United States)

    Izosimov, Igor

    2016-01-01

    Structure of the ground and excited states in halo-like nuclei is discussed. Both the Borromean and tango halo types can be observed for n-p configurations of atomic nuclei.Structure of the halo may be different for the different levels and resonances in atomic nuclei. Isobar analog, double isobar analog, configuration, and double configuration states can simultaneously have n-n, n-p, and p-p halo components in their wave functions. When the halo structure of the excited state differs from that of the ground state, or the ground state has non-halo structure, the γ-transition from the excited state to the ground state can be essentially hindered, i.e. the formation of a specific type of isomers (halo isomers) becomes possible. B(Mγ) and B(Eγ) values for γ-transitions in 6,7,8Li, 8,9,10Be, 8,10,11B, 10,11,12,13,14C, 13,14,15,16,17N, 15,16,17,19O, and 17F are analyzed. Special attention is given to nuclei which ground state does not exhibit halo structure but the excited state (halo isomer) may have one.

  20. Isotope shifts of the (3s3p) 3P0,1,2-(3s4s) 3S1 Mg I transitions

    DEFF Research Database (Denmark)

    He, Ming; Therkildsen, Kasper T.; Jensen, Brian B.

    2009-01-01

    We report measurements of the isotope shifts of the (3s3p)P30,1,2-(3s4s)S31 Mg I transitions for the stable isotopes M24g (I=0) , M25g (I=5/2) , and M26g (I=0) . Furthermore, the M25g S31 hyperfine coefficient A(S31)=(-321.6±1.5)MHz is extracted and found to be in excellent agreement with state...

  1. A method for combined Sr-Nd-Hf isotopic analysis of <10 mg dust samples: implication for ice core science

    Science.gov (United States)

    Ujvari, Gabor; Wegner, Wencke; Klötzli, Urs

    2017-04-01

    Aeolian mineral dust particles below the size of 10-20 μm often experience longer distance transport in the atmosphere, and thus Aeolian dust is considered an important tracer of large-scale atmospheric circulation. Since ice core dust is purely Aeolian in origin, discrimination of its potential source region(s) can contribute to a better understanding of past dust activity and climatic/environmental causes. Furthermore, ice core dust source information provides critical experimental constraints for model simulations of past atmospheric circulation patterns [1,2]. However, to identify dust sources in past dust archives such as ice cores, the mineralogy and geochemistry of the wind-blown dust material must be characterized. While the amount of dust in marine cores or common terrestrial archives is sufficient for different types of analyses and even for multiple repeat measurements, dust content in ice cores is usually extremely low even for the peak dusty periods such as the Last Glacial Maximum (LGM) (5-8 mg dust/kg ice; [3]). Since the most powerful dust fingerprinting methods, such as REE composition and Sr-Nd-Pb isotopic analyses are destructive there is a clear need to establish sequential separation techniques of Sr, Nd, Pb and other REEs to get the most information out of small (5-10 mg) dust samples recovered from ice cores. Although Hf isotopes have recently been added as a robust tool of aerosol/dust source discrimination (e.g. [4,5,6,7]), precise Hf isotopic measurements of small (dispersion in 176Hf/177Hf for the different aliquots of BEI is a unique feature or not. Nevertheless, the ca. 3-7 ɛHf unit difference between the Central European and Chinese dust sample provides an opportunity to better discriminate last glacial Greenland dust sources [7] in Nd-Hf space. This study was supported by the OMAA 92öu7 project, the OTKA PD-108639 grant and the Bolyai János Research Fellowship (to GÚ). References [1] Biscaye et al., 1997. J. Geophys. Res. 102

  2. Origin and Distribution of 26Al and Mg Isotopes in the Solar Protoplanetary Disk

    DEFF Research Database (Denmark)

    Larsen, Kirsten Kolbjørn

    Understanding when and how our solar system formed is perhaps one of the most fundamental questions in natural sciences. The prime cosmochemical tools to achieve this goal are the remnants of the earliest stages of planet formation; meteorites and their components. Evidence for the former presence...... of short-lived radioactive nuclides in these ancient materials is a direct reflection of their recent nucleosynthetic origin prior to or during formation of our young solar system 4.6 Myr ago. Disentangling the origin and distribution of this nucleosynthetic heritage provides a fossil record of the dynamic...... birth environment of our Sun and a unique time-window into the very earliest history of our solar system. Ever since the discovery of its decay product, 26Mg, in primitive solar system objects more than 30 years ago, the short-lived radioactive nuclide, 26Al (t1/2 = 0.73 Myr), has been the optimal...

  3. Study of the dynamics and isotopic effects in the D + MgD reaction using the quasi-classical trajectory method

    Science.gov (United States)

    Huang, Zhuoyao; Li, Rui; Ge, Meihua; Zheng, Yujun; Meng, Xiangjia; Yang, Huan

    2017-10-01

    The dynamics of the D + MgD reaction at low collision energies are conducted in quasi-classical trajectory method (QCT) on three reaction channels, namely nonreactive, D abstraction, and D exchange. Isotopic effects between D + MgD and H + MgH reactions are included mainly in the exchange channel involving both direct and roaming mechanisms. The integral cross sections (ICSs), differential cross sections (DCSs) and state distributions at collision energies ranging from 1 to 9 kcal/mol are presented to show the dynamics and isotopic effects. Important difference can be found in the ro-vibrational state distributions between MgD2 and MgH2 systems.

  4. Late Pliocene Norwegian Greenland Overflow based on benthic stable isotopEs, Mg/Ca, and foraminifera assemblages at ODP Site 984

    Science.gov (United States)

    Weinelt, M.; Bartoli, G.; Erlenkeuser, H.

    2003-04-01

    Increased surface salinity in the Carribean and generally enhanced North Atlantic lower intermediate water ventilation after 4.2 Ma suggest that the closure of the Panama Isthmus favored enhanced heat, salt, and moisture supply to the northern high latitudes and in turn, favored the built up of ice in Greenland and the production of North Atlantic deepwater (Haug &Tiedemann, 1998). The Sediment record of ODP Site 984 (1700m) may serve to test the response and role of the Iceland-Scotland Overflow as key component of NADW over these changing scenarios. Carbonate dissolution cycles at the site were interpreted as a result of corrosive Norwegian Greenland Sea overflow water (Jansen et al., 2000). Though absence of foraminifera over wide parts of glacial stages prevents fully continuous records, high-resolution sampling enabled us to establish benthic stable isotopes records, Mg/Ca temperatures, and faunal assemblages for two time windows, prior (Stages G16-G11) and subsequent (Stages 101-99) to the onset of "Quaternary-style" glaciations at 2.75 Ma. In general, glacial-to-interglacial d18O amplitudes and absolute levels only slightly increase from 0.8‰ (3.8-3‰) in the older window to 1.0‰ (4.2-3.2‰) in the younger window. These amplitudes equal the amplitudes found for planktonic foraminifera at Site 984 and may be attributed to both ice volume and temperature changes. Benthic d13C values suggest a distinct increase in bottom water ventilation from older to younger interglacials (from -0.5 to 1‰). Faunas dominated by Bolivina, Uvigerina, Melonis, and Stilostomella suggest high carbon fluxes during the older interglacials. In the younger window, a fauna dominated by Elphidium suggets low oxygen conditions during glacial stage 100. Ma/Ca concentrations of Uvigerina suggest intermediate water temperatures ranging from 4 to 6°C during interglacial stages 101 and 99. If true, Late Pliocene intermediate water was considerably warmer than today (the Norwegian

  5. Seasonality in the Western Mediterranean During the Last Glacial From Paired Oxygen Isotopes and Mg/Ca in Limpet Shells

    Science.gov (United States)

    Ferguson, J. E.; Henderson, G. M.; Fa, D.; Finlayson, C.

    2008-12-01

    Molluscs have shown great potential to act as seasonal-resolution archives of sea-surface temperatures (SST) at mid to high latitudes, outside the range of tropical surface corals. Seasonal resolution climate records from higher latitudes are important to allow investigation of the role of seasonality in controlling mean climate on diverse timescales, and of the evolution of climate systems such as the North Atlantic Oscillation. Long sequences of intertidal mollusc shells are difficult to find due to sea level fluctuations over glacial- interglacial periods. This study makes use of Patella shells collected by Neanderthals and humans and transported inland to caves on Gibraltar over at least the last 120 kyrs. Some 30 fossil Patella shells were selected from several hundred excavated from Gorham's and Vanguard Caves at Gibraltar. Oxygen isotope analysis of micromilled samples of modern Patella shells from the Gibraltar coastline demonstrate that the shells accurately record absolute SSTs and capture more than 80% of the full seasonal range. Analysis of fossil Patella shells, dated using 14C, provides records of the change in absolute SST and seasonality during the last glacial. Paired Mg/Ca ratios of micromilled samples in modern Patella shells follow a consistent positive relationship with SST providing an independent paleothermometer, analogous with coral Sr/Ca. Applying this Mg/Ca-SST relationship to fossil Patella shells allows the independent reconstruction of the absolute values and range of SSTs and the reconstruction of seawater δ18O for the western Mediterranean. Results show a cooling of glacial summer SSTs from 36 kyr BP to the LGM with maximum cooling of glacial summer SSTs of 7.5 °C relative to modern. In contrast, winter SSTs show greater variability on millennial timescales with a maximum cooling of up to 10 °C. SST seasonality is therefore extended due to greater winter cooling but SST seasonality is highly variable as a result of large

  6. The elemental and Mg isotope geochemistry of primary upper mantle mineral weathering at pH = 1 and T = 25°C

    Science.gov (United States)

    Lee, S.; Ryu, J.; Choi, M.; Kil, Y.; Shin, H.

    2011-12-01

    We conducted a plug flow reactor experiment at pH = 1 and T = 25°C using the 63-245 μm size fraction of crushed olivine(Olv), orthopyroxene(Opx), clinopyroxene(Cpx), and spinel(Spl). The purpose of the study is to characterize the influence of mineral weathering on the Mg isotope geochemistry of terrestrial waters. Eluates were collected every 4 hrs for the first 24 hrs, every 12 hrs for the second 24 hrs, and every 24 hrs thereafter for a total of 480 hrs at the time of writing. Elemental concentrations in output solutions were measured by ICP-OES and values of the percent charge balance error are better than ±5%. When plotted versus time during Opx, Cpx, and Spl dissolutions, concentrations of Al, Ca, Fe, Mg, and Si in the eluate display a rapid decrease followed by a decay to zero. It is attributed that these minerals dissolve faster than they mechanically disaggregate. In contrast, concentrations of Fe, Mg, and Si during Olv dissolution display a rapid increase followed by a decrease and finally a decay to zero. We attribute the initial concentration increase to leaching of freshly cleaved mineral surfaces. All solutions are undersaturated with respect to secondary phases. The profiles are described using coupled conservation equations for the solid and fluid solved at non-steady-state. Mg isotope measurement is underway by MC-ICP-MS. We will use the elemental chemistry model to constrain the behavior of Mg isotope and quantify potential isotopic fractionation.

  7. Neutron halos in hypernuclei

    CERN Document Server

    Lue, H F; Meng, J; Zhou, S G

    2003-01-01

    Properties of single-LAMBDA and double-LAMBDA hypernuclei for even-N Ca isotopes ranging from the proton dripline to the neutron dripline are studied using the relativistic continuum Hartree-Bogolyubov theory with a zero-range pairing interaction. Compared with ordinary nuclei, the addition of one or two LAMBDA-hyperons lowers the Fermi level. The predicted neutron dripline nuclei are, respectively, sup 7 sup 5 subLAMBDA Ca and sup 7 sup 6 sub 2 subLAMBDA Ca, as the additional attractive force provided by the LAMBDA-N interaction shifts nuclei from outside to inside the dripline. Therefore, the last bound hypernuclei have two more neutrons than the corresponding ordinary nuclei. Based on the analysis of two-neutron separation energies, neutron single-particle energy levels, the contribution of continuum and nucleon density distribution, giant halo phenomena due to the pairing correlation, and the contribution from the continuum are suggested to exist in Ca hypernuclei similar to those that appear in ordinary ...

  8. Isospin in halo nuclei: Borromean halo, tango halo, and halo isomers

    Science.gov (United States)

    Izosimov, I. N.

    2017-09-01

    It is shown that the wave functions for isobaric analog, double isobaric analog, configuration, and double configuration states may simultaneously have components corresponding to nn, np, and pp halos. The difference in the halo structure between the ground and excited states of a nucleus may lead to the formation of halo isomers. A halo structure of both Borromean and tango types can be observed for np configurations. The structure of ground and excited states with various isospins in halo-like nuclei is discussed. The reduced probabilities B( Mλ) and B( Eλ) for gamma transitions in 6-8Li, 8-10Be, 8,10,11B, 10-14C, 13-17N, 15-17,19O, and 17F nuclei are analyzed. Particular attention is given to the cases where the ground state of a nucleus does not have a halo structure, but where its excited state may have it.

  9. The elemental and Mg isotope geochemistry of biotite, chlorite, and hornblende weathering at pH = 1 and T = 25°C

    Science.gov (United States)

    Ryu, J.; Lee, S.; Choi, M.; Shin, H.; Kim, Y.

    2011-12-01

    We conducted a plug flow reactor experiment at pH = 1 and T = 25°C using the 63-245 μm size fraction of crushed biotite, chlorite, and hornblende. The purpose of the study is to constrain the influence of mineral weathering on the Mg isotope geochemistry of terrestrial waters. Eluates were collected every 4 hrs for the first 24 hrs, every 12 hrs for the second 24 hrs, and every 24 hrs thereafter for a total of 381 hrs at the time of writing. Elemental concentrations were measured by ICP-OES and values of the percent charge balance error are better than ±5%. When plotted versus time during biotite dissolution, concentrations of Al, Fe, Mg, and Si in the eluate display a rapid decrease followed by a rise and a steady-state. In contrast, concentrations of Ca and Sr display a rapid decrease followed by a decay to zero. During chlorite and hornblende dissolution, concentrations of all elements display a rapid decrease followed by a decay to zero. We attribute the initial concentration decrease to either calcite dissolution or leaching of freshly cleaved mineral surfaces. All solutions are undersaturated with respect to secondary phases. The profiles are described using coupled conservation equations for the solid and fluid solved at non-steady-state. The equations yield dissolution rates in good agreement with previous studies. Mg isotope measurement is underway by MC-ICP-MS. We will use the elemental chemistry model to constrain the behavior of Mg isotope and quantify potential isotopic fractionation.

  10. Are recycled carbonates essential to explain light Mg isotopes in magmatic rocks? Insights from Late Cenozoic mantle-derived magmas in Iran

    Science.gov (United States)

    Pang, K. N.; Teng, F. Z.; Sun, Y.; Chung, S. L.; Zarrinkoub, M. H.

    2016-12-01

    Mantle-derived magmas at continental collision zones represent probes into the mantle that might have been variably metasomatized prior to collision. To address how and to what extent mantle metasomatism occurred, particularly for the role of recycled carbonates, we conducted a Mg isotopic study of two suites of Late Cenozoic mantle-derived magmas in Iran, part of the Arabia-Eurasia collision zone preceded by the long-lasting Tethyan subduction. The Qal'eh Hasan Ali high-Mg ultrapotassic rocks, low-degree partial melts from the metasomatized lithospheric mantle, have mantle-like δ26Mg (-0.23 to -0.28 ‰) despite high CaO/Al2O3 and Zr/Hf, low Ti/Eu and Hf/Sm, and presence of carbonate globules in devitrified glass indicative of carbonate or carbonatite involvement in their genesis. The absence of light Mg isotopic composition of these rocks indicates that either the recycled carbonates were in the form of calcitic rather than dolomitic melts, or the amount of Mg from the carbonatite was too little to appear in these rocks. The Lut-Sistan alkali basalts, sodic magmas suggested to have derived from low-degree melting of the asthenosphere followed by variable differentiation, display a range of δ26Mg from -0.17 to -0.26 ‰ with three outlying data at -0.37‰, -0.39‰ and -0.56 ‰. The samples with light Mg isotopes do not show greater influence by carbonate or carbonatite in terms of the elemental indices noted above. Instead, they are characterized by lower light and middle REE abundances and slightly lower initial 143Nd/144Nd than the majority of samples. The covariations can be explained by minor incorporation of lower crustal garnet during magma ascent through local thickened crust in the collision zone. We propose that thickened crust where garnet pyroxenites exist is capable of imparting a light Mg isotopic signature to mantle-derived magmas, and that such signature is not unique to the involvement of carbonate or carbonatite in the mantle source.

  11. A combined Sm-Nd, Rb-Sr, and U-Pb isotopic study of Mg-suite norite 78238: Further evidence for early differentiation of the Moon

    Energy Technology Data Exchange (ETDEWEB)

    Edmunson, J; E.Borg, L; Nyquist, L E; Asmerom, Y

    2008-11-17

    Lunar Mg-suite norite 78238 was dated using the Sm-Nd, Rb-Sr, and U-Pb isotopic systems in order to constrain the age of lunar magma ocean solidification and the beginning of Mg-suite magmatism, as well as to provide a direct comparison between the three isotopic systems. The Sm-Nd isotopic system yields a crystallization age for 78238 of 4334 {+-} 37 Ma and an initial {var_epsilon}{sub Nd}{sup 143} value of -0.27 {+-} 0.74. The age-initial {var_epsilon}{sub Nd}{sup 143} (T-I) systematics of a variety of KREEP-rich samples, including 78238 and other Mg-suite rocks, KREEP basalts, and olivine cumulate NWA 773, suggest that lunar differentiation was completed by 4492 {+-} 61 Ma assuming a Chondritic Uniform Reservoir bulk composition for the Moon. The Rb-Sr isotopic systematics of 78238 were disturbed by post-crystallization processes. Nevertheless, selected data points yield two Rb-Sr isochrons. One is concordant with the Sm-Nd crystallization age, 4366 {+-} 53 Ma. The other is 4003 {+-} 95 Ma and is concordant with an Ar-Ar age for 78236. The {sup 207}Pb-{sup 206}Pb age of 4333 {+-} 59 Ma is concordant with the Sm-Nd age. The U-Pb isotopic systematics of 78238 yield linear arrays equivalent to younger ages than the Pb-Pb system, and may reflect fractionation of U and Pb during sample handling. Despite the disturbed nature of the U-Pb systems, a time-averaged {mu} ({sup 238}U/{sup 204}Pb) value of the source can be estimated at 27 {+-} 30 from the Pb-Pb isotopic systematics. Because KREEP-rich samples are likely to be derived from source regions with the highest U/Pb ratios, the relatively low {mu} value calculated for the 78238 source suggests the bulk Moon does not have an exceedingly high {mu} value.

  12. ALFA beam halo

    CERN Document Server

    Komarek, Tomas

    2014-01-01

    This note serves as a final report about CERN Summer Student Programme 2014 project. The beam halo is an undesired phenomenon for physics analyses on particle accelerators. It surrounds the beam core and constitutes an important part of background for signal measurements on some detectors, eg. in the forward region. In this study, the data from the ALFA detector were used, specifically from the run 191373 ($\\beta^*=90\\unit{m}$) and the run 213268 ($\\beta^*=1\\unit{km}$). Using the ROOT framework, a software for beam halo events selection was created and beam halo properties were examined. In the run 213268, excessive beam halo is suspected to be the reason for multiple beam scrapings that occurred. A kinematic reconstruction of beam halo particles is attempted in order to understand beam halo properties in the interaction point. Some further simulations are employed to find constraints for beam halo particles in order to survive in the accelerator for a longer time/many revolutions. This work represents a st...

  13. Investigating the hydrological significance of stalagmite geochemistry (Mg, Sr) using Sr isotope and particulate element records across the Late Glacial-to-Holocene transition

    Science.gov (United States)

    Belli, R.; Borsato, A.; Frisia, S.; Drysdale, R.; Maas, R.; Greig, A.

    2017-02-01

    The trace element and Sr isotope records in two coeval stalagmites characterized by different growth rates and flow regimes at Savi cave (Grotta Savi, NE Italy) reveal different sources and incorporation mechanisms for Mg and Sr. Mg is sourced primarily from dissolved cave host rock while particulate Mg derived from soil plays a subordinate role. The presence of particulate-borne Mg is inferred from the co-variation of Mg and particle-associated elements (Th, Al and Mn) which are preferentially concentrated in open columnar calcite layers. Variation in Mg concentrations corrected for particle-influenced components, the Mgc parameter, is controlled by water-rock interaction, with higher and lower Mgc during dry and wet phases, respectively. This is thought to reflect incongruent dissolution of Mg-rich phases. Correction of Sr concentrations for contributions from airborne exogenic Sr, based on 87Sr/86Sr ratios, yields the bedrock-only contribution (Src). Src variation in stalagmite calcite is influenced by speleothem growth rate and by variation of the calcite-water Sr partitioning in wet and dry phases, and only to a minor extent by incongruent dissolution of Mg-rich phases. Concentration profiles for Mgc and Srcg (corrected for growth rate effects) show inverse correlations and are inferred to show hydrological significance which is captured in a hydrological index, HI. We suggest HI provides robust information on water-rock interaction related to hydrological changes and can be utilized in both wet and semi-arid environments, provided the corrections for soil Mg and exogenic Sr can be applied with confidence. Application of the HI index allows correction of Grotta Savi oxygen isotope data, to yield a δ18Oc time series that shows when changes in moisture sources and atmospheric reorganization, or changes in moisture amount, were significant. This is especially evident during the Younger Dryas (YD). The Savi record supports the concept of a two-phase YD, marked by

  14. What's a Halo?

    Science.gov (United States)

    ... Development Infections Diseases & Conditions Pregnancy & Baby Nutrition & Fitness Emotions & Behavior School & Family Life First Aid & Safety Doctors & ... of quick or jerky movements, like jumping or dancing pulling or tugging on the halo or attached ...

  15. Haloes and clustering in light, neutron-rich nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Orr, N.A

    2001-10-01

    Clustering is a relatively widespread phenomenon which takes on many guises across the nuclear landscape. Selected topics concerning the study of halo systems and clustering in light, neutron-rich nuclei are discussed here through illustrative examples taken from the Be isotopic chain. (author)

  16. Spectrum of Sprite Halos

    Czech Academy of Sciences Publication Activity Database

    Gordillo-Vázquez, F.J.; Luque, A.; Šimek, Milan

    2011-01-01

    Roč. 116, č. 9 (2011), A09319-A09319 ISSN 0148-0227 Institutional research plan: CEZ:AV0Z20430508 Keywords : sprites * halos * spectroscopy Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 3.021, year: 2011 http://www.trappa.iaa.es/sites/all/files/papers/isi_journal_papers/2011/2011_08.pdf

  17. Tracking the LHC halo

    CERN Document Server

    Antonella Del Rosso

    2015-01-01

    In the LHC, beams of 25-ns-spaced proton bunches travel at almost the speed of light and pass through many different devices installed along the ring that monitor their properties. During their whirling motion, beam particles might interact with the collimation instrumentation or with residual gas in the vacuum chambers and this creates the beam halo – an annoying source of background for the physics data. Newly installed CMS sub-detectors are now able to monitor it.   The Beam Halo Monitors (BHM) are installed around the CMS rotating shielding. The BHM are designed and built by University of Minnesota, CERN, Princeton University, INFN Bologna and the National Technical University of Athens. (Image: Andrea Manna). The Beam Halo Monitor (BHM) is a set of 20 Cherenkov radiators – 10-cm-long quartz crystals – installed at each end of the huge CMS detector. Their design goal is to measure the particles that can cause the so-called “machine-induced...

  18. Western Indian Ocean circulation and climate variability on different time scales. A study based on stable oxygen and carbon isotopes, benthic foraminiferal assemblages and Mg/Ca paleothermometry

    Energy Technology Data Exchange (ETDEWEB)

    Romahn, Sarah

    2014-08-19

    In order to understand the Earth's climate evolution it is crucial to evaluate the role of low-latitude oceans in the global climate system, as they are connected to both hemispheres via atmospheric and oceanic circulation and thus hold the potential to disentangle the asynchronicity of short-term Pleistocene climate variability. However, the potential of low latitude oceans to respond to and force large-scale changes of the climate system is still debated. The aim of this thesis is to examine and to understand the causal relationship of both atmospheric and oceanic changes in the tropical western Indian Ocean on centennial-, millennial and glacial-interglacial timescales. For this purpose I investigated stable oxygen and carbon isotope compositions of both planktic and benthic foraminiferal tests, Mg/Ca ratios of planktic foraminiferal tests as well as benthic foraminiferal assemblages and sedimentary geochemical parameters on two sediment cores (GeoB12615-4, 446 m and GeoB12616-4, 1449 m) from the continental slope off Tanzania, East Africa.

  19. Cosmic web type dependence of halo clustering

    Science.gov (United States)

    Fisher, J. D.; Faltenbacher, A.

    2018-01-01

    We use the Millennium Simulation to show that halo clustering varies significantly with cosmic web type. Haloes are classified as node, filament, sheet and void haloes based on the eigenvalue decomposition of the velocity shear tensor. The velocity field is sampled by the peculiar velocities of a fixed number of neighbouring haloes, and spatial derivatives are computed using a kernel borrowed from smoothed particle hydrodynamics. The classification scheme is used to examine the clustering of haloes as a function of web type for haloes with masses larger than 1011 h- 1 M⊙. We find that node haloes show positive bias, filament haloes show negligible bias and void and sheet haloes are antibiased independent of halo mass. Our findings suggest that the mass dependence of halo clustering is rooted in the composition of web types as a function of halo mass. The substantial fraction of node-type haloes for halo masses ≳ 2 × 1013 h- 1 M⊙ leads to positive bias. Filament-type haloes prevail at intermediate masses, 1012-1013 h- 1 M⊙, resulting in unbiased clustering. The large contribution of sheet-type haloes at low halo masses ≲ 1012 h- 1 M⊙ generates antibiasing.

  20. Black holes with halos

    Science.gov (United States)

    Monten, Ruben; Toldo, Chiara

    2018-02-01

    We present new AdS4 black hole solutions in N =2 gauged supergravity coupled to vector and hypermultiplets. We focus on a particular consistent truncation of M-theory on the homogeneous Sasaki–Einstein seven-manifold M 111, characterized by the presence of one Betti vector multiplet. We numerically construct static and spherically symmetric black holes with electric and magnetic charges, corresponding to M2 and M5 branes wrapping non-contractible cycles of the internal manifold. The novel feature characterizing these nonzero temperature configurations is the presence of a massive vector field halo. Moreover, we verify the first law of black hole mechanics and we study the thermodynamics in the canonical ensemble. We analyze the behavior of the massive vector field condensate across the small-large black hole phase transition and we interpret the process in the dual field theory.

  1. Charge Radius Measurement of the Halo Nucleus $^{11}$Li

    CERN Multimedia

    Kluge, H-J; Kuehl, T; Simon, H; Wang, Haiming; Zimmermann, C; Onishi, T; Tanihata, I; Wakasugi, M

    2002-01-01

    %IS385 %title\\\\ \\\\The root-mean-square charge radius of $^{11}$Li will be determined by measuring the isotope shift of a suitable atomic transition in a laser spectroscopic experiment. Comparing the charge radii of the lithium isotopes obtained by this nuclear-model-independent method with the relevant mass radii obtained before will help to answer the question whether the proton distribution in halo nuclei at the neutron drip-line is decoupled to the first order from their neutron distribution. The necessary experimental sensitivity requires the maximum possible rate of $^{11}$Li nuclei in a beam of low emittance which can only be provided by ISOLDE.

  2. The Excursion Set Theory of Halo Mass Functions, Halo Clustering, and Halo Growth

    Science.gov (United States)

    Zentner, Andrew R.

    I review the excursion set theory with particular attention toward applications to cold dark matter halo formation and growth, halo abundance, and halo clustering. After a brief introduction to notation and conventions, I begin by recounting the heuristic argument leading to the mass function of bound objects given by Press and Schechter. I then review the more formal derivation of the Press-Schechter halo mass function that makes use of excursion sets of the density field. The excursion set formalism is powerful and can be applied to numerous other problems. I review the excursion set formalism for describing both halo clustering and bias and the properties of void regions. As one of the most enduring legacies of the excursion set approach and one of its most common applications, I spend considerable time reviewing the excursion set theory of halo growth. This section of the review culminates with the description of two Monte Carlo methods for generating ensembles of halo mass accretion histories. In the last section, I emphasize that the standard excursion set approach is the result of several simplifying assumptions. Dropping these assumptions can lead to more faithful predictions and open excursion set theory to new applications. One such assumption is that the height of the barriers that define collapsed objects is a constant function of scale. I illustrate the implementation of the excursion set approach for barriers of arbitrary shape. One such application is the now well-known improvement of the excursion set mass function derived from the "moving" barrier for ellipsoidal collapse. I also emphasize that the statement that halo accretion histories are independent of halo environment in the excursion set approach is not a general prediction of the theory. It is a simplifying assumption. I review the method for constructing correlated random walks of the density field in the more general case. I construct a simple toy model to illustrate that excursion set

  3. Outflow vs. Infall in Spiral Galaxies: Metal Absorption in the Halo of NGC 891

    OpenAIRE

    Bregman, Joel N.; Miller, Eric D.; Seitzer, Patrick; Cowley, C. R.; Miller, Matthew J.

    2013-01-01

    Gas accreting onto a galaxy will be of low metallicity while halo gas due to a galactic fountain will be of near-solar metallicity. We test these predictions by measuring the metal absorption line properties of halo gas 5 kpc above the plane of the edge-on galaxy NGC 891, using observations taken with HST/STIS toward a bright background quasar. Metal absorption lines of Fe II, Mg II, and Mg I in the halo of NGC 891 are clearly seen, and when combined with recent deep H I observations, we are ...

  4. Halo modelling in chameleon theories

    Energy Technology Data Exchange (ETDEWEB)

    Lombriser, Lucas; Koyama, Kazuya [Institute of Cosmology and Gravitation, University of Portsmouth, Dennis Sciama Building, Burnaby Road, Portsmouth, PO1 3FX (United Kingdom); Li, Baojiu, E-mail: lucas.lombriser@port.ac.uk, E-mail: kazuya.koyama@port.ac.uk, E-mail: baojiu.li@durham.ac.uk [Institute for Computational Cosmology, Ogden Centre for Fundamental Physics, Department of Physics, University of Durham, Science Laboratories, South Road, Durham, DH1 3LE (United Kingdom)

    2014-03-01

    We analyse modelling techniques for the large-scale structure formed in scalar-tensor theories of constant Brans-Dicke parameter which match the concordance model background expansion history and produce a chameleon suppression of the gravitational modification in high-density regions. Thereby, we use a mass and environment dependent chameleon spherical collapse model, the Sheth-Tormen halo mass function and linear halo bias, the Navarro-Frenk-White halo density profile, and the halo model. Furthermore, using the spherical collapse model, we extrapolate a chameleon mass-concentration scaling relation from a ΛCDM prescription calibrated to N-body simulations. We also provide constraints on the model parameters to ensure viability on local scales. We test our description of the halo mass function and nonlinear matter power spectrum against the respective observables extracted from large-volume and high-resolution N-body simulations in the limiting case of f(R) gravity, corresponding to a vanishing Brans-Dicke parameter. We find good agreement between the two; the halo model provides a good qualitative description of the shape of the relative enhancement of the f(R) matter power spectrum with respect to ΛCDM caused by the extra attractive gravitational force but fails to recover the correct amplitude. Introducing an effective linear power spectrum in the computation of the two-halo term to account for an underestimation of the chameleon suppression at intermediate scales in our approach, we accurately reproduce the measurements from the N-body simulations.

  5. Conditions of stichtite (Mg6Cr2(OH)16[CO3]·4H2O) formation and its geochemical and isotope record of early phanerozoic serpentinizing environments

    Science.gov (United States)

    Melchiorre, Erik B.; Bottrill, Ralph; Huss, Gary R.; Lopez, Amanda

    2017-01-01

    Stichtite is a magnesium-chromium hydroxycarbonate mineral found in association with early Phanerozoic chromite-rich serpentinite rocks of Tasmania, Australia and Tehuitzingo, Mexico. Elemental analysis of stichtite shows a range of compositions within the Cr-Fe-Al hydrotalcite group, with compositional trends associated with each discrete serpentinite host body. Elemental and textural analysis of stichtite-associated chromite indicates that stichtite forms in fore-arc setting rocks through interaction of chromite and methane-rich serpentinizing fluids. The degree to which chromite is replaced by stichtite is inferred to correlate with the length of time that the host rocks spent within the ;stichtite window.; Carbon stable-isotope analyses of stichtite suggest carbon sourcing from marine kerogen with a minor marine carbonate component in some samples. The carbon and hydrogen stable isotope profile of stichtite ranges from the field of methane from active serpentinizing zones, to organic thermogenic methane. The association of the stichtite 2H polytype (nee barbertonite) with aragonite ± antigorite suggests this is a higher pressure/temperature polytype of stichtite. Reaction completion textures, isotopic values, and qualitative mineral thermobarometric indicators indicate that stichtite forms during serpentinization of fore-arc setting rocks in a methane/H2-rich environment within fluid conduits, ranging from low temperatures and pressures near the surface, to depths where pressure is up to 0.8-1.2 GPa and temperature is up to ∼300 °C. These unique chemical, isotopic, and textural properties of stichtite from distinct serpentinite bodies likely record the duration of serpentinization at specific thermobarometric conditions, and provide a window into the conditions associated with a potentially habitable environment on early Earth and other bodies of the solar system.

  6. Relativistic Hartree-Bogoliubov description of the halo nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Meng, J.; Ring, P. [Universitaet Muenchen, Garching (Germany)

    1996-12-31

    Here the authors report the development of the relativistic Hartree-Bogoliubov theory in coordinate space. Pairing correlations are taken into account by both density dependent force of zero range and finite range Gogny force. As a primary application the relativistic HB theory is used to describe the chain of Lithium isotopes reaching from {sup 6}Li to {sup 11}Li. In contrast to earlier investigations within a relativistic mean field theory and a density dependent Hartree Fock theory, where the halo in {sup 11}Li could only be reproduced by an artificial shift of the 1p{sub 1/2} level close to the continuum limit, the halo is now reproduced in a self-consistent way without further modifications using the scattering of Cooper pairs to the 2s{sub 1/2} level in the continuum. Excellent agreement with recent experimental data is observed.

  7. Galaxy models with live halos

    CERN Document Server

    Sellwood, J A

    1980-01-01

    Computer models of galaxies are described, in which the disc stars and the halo stars are both treated fully self consistently. These were used to test the validity of the 'rigid halo' approximation usually employed when studying the instabilities of a disc of stars. The models show that very little interaction between the populations occurs while the disc remains nearly axisymmetric, but a strong bar is able to transfer angular momentum from the disc to the halo. The global bar stability of the disc is not greatly affected by the interaction between the two stellar populations, and it is found that a large fraction of the total galactic mass is still required in the spheroidal component if bar formation is to be prevented. (36 refs).

  8. Halo-free Phase Contrast Microscopy

    National Research Council Canada - National Science Library

    Tan H Nguyen; Mikhail Kandel; Haadi M Shakir; Catherine Best-popescu; Jyothi Arikkath; Minh N Do; Gabriel Popescu

    2017-01-01

    We present a new approach for retrieving halo-free phase contrast microscopy (hfPC) images by upgrading the conventional PC microscope with an external interferometric module, which generates sufficient data for reversing the halo artifact...

  9. Rb-Sr, Sm-Nd and Lu-Hf isotope systematics of the lunar Mg-suite: the age of the lunar crust and its relation to the time of Moon formation.

    Science.gov (United States)

    Carlson, Richard W; Borg, Lars E; Gaffney, Amy M; Boyet, Maud

    2014-09-13

    New Rb-Sr, (146,147)Sm-(142,143)Nd and Lu-Hf isotopic analyses of Mg-suite lunar crustal rocks 67667, 76335, 77215 and 78238, including an internal isochron for norite 77215, were undertaken to better define the time and duration of lunar crust formation and the history of the source materials of the Mg-suite. Isochron ages determined in this study for 77215 are: Rb-Sr=4450±270 Ma, (147)Sm-(143)Nd=4283±23 Ma and Lu-Hf=4421±68 Ma. The data define an initial (146)Sm/(144)Sm ratio of 0.00193±0.00092 corresponding to ages between 4348 and 4413 Ma depending on the half-life and initial abundance used for (146)Sm. The initial Nd and Hf isotopic compositions of all samples indicate a source region with slight enrichment in the incompatible elements in accord with previous suggestions that the Mg-suite crustal rocks contain a component of KREEP. The Sm/Nd-(142)Nd/(144)Nd correlation shown by both ferroan anorthosite and Mg-suite rocks is coincident with the trend defined by mare and KREEP basalts, the slope of which corresponds to ages between 4.35 and 4.45 Ga. These data, along with similar ages for various early Earth differentiation events, are in accord with the model of lunar formation via giant impact into Earth at ca 4.4 Ga. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  10. Visibility of halos and rainbows.

    Science.gov (United States)

    Gedzelman, S D

    1980-09-15

    A theory for the visibility of halos and rainbows is presented. The light reaching the observer's eye from the direction of the halo or rainbow is assumed to consist of two parts: (1) a beam of singly scattered sunlight (or moonlight) from a cloud of ice crystals or a rainswath, which, in turn, has suffered depletion by scattering or absorption in its passage to the observer, and (2) the general background brightness. The model is able to account for several long-known qualitative observations concerning halos, namely, that the brightest halos are produced by optically thin cirrostratus clouds (i.e., for which the cloud optical depth tau(c), rainbow the brightness of the beam increases monotonically with the optical depth tau(R) of the sunlit part of the rainswath, but the increase is quite small for tau(R) >/=1. On the other hand, the brightness of the background increases more rapidly with tau(R) for tau(R)> 1 so that the rainbow appears most easily visible for tau(R) less, similar1. This implies that the most easily visible rainbows are produced by light or moderate showers rather than heavy downpours. Finally, suggestions are made for applying the theory to other atmospheric optical phenomena, such as coronas and glories.

  11. Halo Mitigation Using Nonlinear Lattices

    CERN Document Server

    Sonnad, Kiran G

    2005-01-01

    This work shows that halos in beams with space charge effects can be controlled by combining nonlinear focusing and collimation. The study relies on Particle-in-Cell (PIC) simulations for a one dimensional, continuous focusing model. The PIC simulation results show that nonlinear focusing leads to damping of the beam oscillations thereby reducing the mismatch. It is well established that reduced mismatch leads to reduced halo formation. However, the nonlinear damping is accompanied by emittance growth causing the beam to spread in phase space. As a result, inducing nonlinear damping alone cannot help mitigate the halo. To compensate for this expansion in phase space, the beam is collimated in the simulation and further evolution of the beam shows that the halo is not regenerated. The focusing model used in the PIC is analysed using the Lie Transform perturbation theory showing that by averaging over a lattice period, one can reuduce the focusing force to a form that is identical to that used in the PIC simula...

  12. Mg/Ca, Sr/Ca, and stable-isotope (δ18O and δ13C) ratio profiles from the fan mussel Pinna nobilis: Seasonal records and temperature relationships

    Science.gov (United States)

    Freitas, Pedro; Clarke, Leon J.; Kennedy, Hilary; Richardson, Christopher; Abrantes, FáTima

    2005-04-01

    We present new annually resolved δ18O, δ13C, Mg/Ca, and Sr/Ca ratio records for two shells of the fast growing Mediterranean fan mussel Pinna nobilis, collected from proximal Spanish coast sea grass meadows. The relationship between the potential geochemical proxies and ontogenetic and environmental controlling factors is investigated. Specifically, the use of shell Mg/Ca and Sr/Ca ratios as potential calcification temperature proxies, the latter calculated from measured shell δ18O values, has been assessed. The δ18O cycles along the growth axis indicate that our P. nobilis specimens are ˜10.5 and ˜4.5 years old. Shell Sr/Ca ratios do not exhibit any consistent interannual cyclicity and are not correlated to temperature. A subtle ontogenetic effect on shell Mg/Ca ratios was observed during the first 4.5 years of recorded growth but was highly evident during the organism's later growth years. In P. nobilis shells, different mechanisms influence ontogenetic variation in shell Mg/Ca and δ18O records. Shell Mg/Ca ratios from the first 4.5 years of growth correlate significantly to temperature, in a best fit relationship described by the equation Mg/Ca = 17.16 ± 1.95 * exp(0.022 ± 0.004 * T). P. nobilis shell Mg/Ca records therefore are a valid temperature proxy only during an early growth phase. For the same range of temperatures, shell Mg/Ca ratios in P. nobilis are approximately 1/3 lower than those reported for inorganic calcite but 3 to 4 times higher than in another bivalve species, Mytilus trossulus, and 4 to 16 times higher than in foraminifera. We suggest these offsets are due to a higher degree of similarity between seawater and calcification-fluid composition in P. nobilis than in other bivalves and foraminifera. The observed shell Mg/Ca ratio change per °C of 2.2% also is lower than that observed for inorganic and other biogenic calcites. Our findings strongly support taxon- and species-specific Mg/Ca-temperature relationships for bivalves and

  13. Galaxy and Mass Assembly (GAMA): halo formation times and halo assembly bias on the cosmic web

    Science.gov (United States)

    Tojeiro, Rita; Eardley, Elizabeth; Peacock, John A.; Norberg, Peder; Alpaslan, Mehmet; Driver, Simon P.; Henriques, Bruno; Hopkins, Andrew M.; Kafle, Prajwal R.; Robotham, Aaron S. G.; Thomas, Peter; Tonini, Chiara; Wild, Vivienne

    2017-09-01

    We present evidence for halo assembly bias as a function of geometric environment (GE). By classifying Galaxy and Mass Assembly (GAMA) galaxy groups as residing in voids, sheets, filaments or knots using a tidal tensor method, we find that low-mass haloes that reside in knots are older than haloes of the same mass that reside in voids. This result provides direct support to theories that link strong halo tidal interactions with halo assembly times. The trend with GE is reversed at large halo mass, with haloes in knots being younger than haloes of the same mass in voids. We find a clear signal of halo downsizing - more massive haloes host galaxies that assembled their stars earlier. This overall trend holds independently of GE. We support our analysis with an in-depth exploration of the L-Galaxies semi-analytic model, used here to correlate several galaxy properties with three different definitions of halo formation time. We find a complex relationship between halo formation time and galaxy properties, with significant scatter. We confirm that stellar mass to halo mass ratio, specific star formation rate (SFR) and mass-weighed age are reasonable proxies of halo formation time, especially at low halo masses. Instantaneous SFR is a poor indicator at all halo masses. Using the same semi-analytic model, we create mock spectral observations using complex star formation and chemical enrichment histories, which approximately mimic GAMA's typical signal-to-noise ratio and wavelength range. We use these mocks to assert how well potential proxies of halo formation time may be recovered from GAMA-like spectroscopic data.

  14. Unbound particles in dark matter halos

    Energy Technology Data Exchange (ETDEWEB)

    Behroozi, Peter S.; Loeb, Abraham; Wechsler, Risa H.

    2013-06-13

    We investigate unbound dark matter particles in halos by tracing particle trajectories in a simulation run to the far future (a = 100). We find that the traditional sum of kinetic and potential energies is a very poor predictor of which dark matter particles will eventually become unbound from halos. We also study the mass fraction of unbound particles, which increases strongly towards the edges of halos, and decreases significantly at higher redshifts. We discuss implications for dark matter detection experiments, precision calibrations of the halo mass function, the use of baryon fractions to constrain dark energy, and searches for intergalactic supernovae.

  15. Halo scale predictions of symmetron modified gravity

    Energy Technology Data Exchange (ETDEWEB)

    Clampitt, Joseph; Jain, Bhuvnesh; Khoury, Justin, E-mail: clampitt@sas.upenn.edu, E-mail: bjain@physics.upenn.edu, E-mail: jkhoury@sas.upenn.edu [Center for Particle Cosmology and Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd St., Philadelphia, PA 19104 (United States)

    2012-01-01

    We offer predictions of symmetron modified gravity in the neighborhood of realistic dark matter halos. The predictions for the fifth force are obtained by solving the nonlinear symmetron equation of motion in the spherical NFW approximation. In addition, we compare the three major known screening mechanisms: Vainshtein, Chameleon, and Symmetron around such dark matter halos, emphasizing the significant differences between them and highlighting observational tests which exploit these differences. Finally, we demonstrate the host halo environmental screening effect (''blanket screening'') on smaller satellite halos by solving for the modified forces around a density profile which is the sum of satellite and approximate host components.

  16. Labelling HaloTag Fusion Proteins with HaloTag Ligand in Living Cells.

    Science.gov (United States)

    Duc, Huy Nguyen; Ren, Xiaojun

    2017-09-05

    HaloTag has been widely used to label proteins in vitro and in vivo (Los et al., 2008). In this protocol, we describe labelling HaloTag-Cbx fusion proteins by HaloTag ligands for live-cell single-molecule imaging (Zhen et al., 2016).

  17. Labelling HaloTag Fusion Proteins with HaloTag Ligand in Living Cells

    OpenAIRE

    Duc, Huy Nguyen; Ren, Xiaojun

    2017-01-01

    HaloTag has been widely used to label proteins in vitro and in vivo (Los et al., 2008). In this protocol, we describe labelling HaloTag-Cbx fusion proteins by HaloTag ligands for live-cell single-molecule imaging (Zhen et al., 2016).

  18. UARS Halogen Occultation Experiment (HALOE) Level 2 V001

    Data.gov (United States)

    National Aeronautics and Space Administration — The HALOE home page on the WWW is http://haloe.gats-inc.com/home/index.php The Halogen Occultation Experiment (HALOE) on NASA's Upper Atmosphere Research Satellite...

  19. Studying dark matter haloes with weak lensing

    NARCIS (Netherlands)

    Velander, Malin Barbro Margareta

    2012-01-01

    Our Universe is comprised not only of normal matter but also of unknown components: dark matter and dark energy. This Thesis recounts studies of dark matter haloes, using a technique known as weak gravitational lensing, in order to learn more about the nature of these dark components. The haloes

  20. Halo abundances and shear in void models

    DEFF Research Database (Denmark)

    Alonso, David; García-Bellido, Juan; Haugbølle, Troels

    2012-01-01

    We study the non-linear gravitational collapse of dark matter into halos through numerical N-body simulations of Lemaitre-Tolman-Bondi void models. We extend the halo mass function formalism to these models in a consistent way. This extension not only compares well with the simulated data at all...

  1. Analytical halo model of galactic conformity

    Science.gov (United States)

    Pahwa, Isha; Paranjape, Aseem

    2017-09-01

    We present a fully analytical halo model of colour-dependent clustering that incorporates the effects of galactic conformity in a halo occupation distribution framework. The model, based on our previous numerical work, describes conformity through a correlation between the colour of a galaxy and the concentration of its parent halo, leading to a correlation between central and satellite galaxy colours at fixed halo mass. The strength of the correlation is set by a tunable 'group quenching efficiency', and the model can separately describe group-level correlations between galaxy colour (1-halo conformity) and large-scale correlations induced by assembly bias (2-halo conformity). We validate our analytical results using clustering measurements in mock galaxy catalogues, finding that the model is accurate at the 10-20 per cent level for a wide range of luminosities and length-scales. We apply the formalism to interpret the colour-dependent clustering of galaxies in the Sloan Digital Sky Survey (SDSS). We find good overall agreement between the data and a model that has 1-halo conformity at a level consistent with previous results based on an SDSS group catalogue, although the clustering data require satellites to be redder than suggested by the group catalogue. Within our modelling uncertainties, however, we do not find strong evidence of 2-halo conformity driven by assembly bias in SDSS clustering.

  2. MODIFIED DYNAMICS (MOND) AS A DARK HALO

    NARCIS (Netherlands)

    SANDERS, RH; BEGEMAN, KG

    1994-01-01

    We propose a form for dark haloes that embodies the fundamental aspect of Milgrom's modified dynamics (MOND): the discrepancy between the visible mass and the Newtonian dynamical mass appears below a critical acceleration. This is a halo having a density distribution, at least to several tens of

  3. Galactic stellar haloes in the CDM model

    NARCIS (Netherlands)

    Cooper, A. P.; Cole, S.; Frenk, C. S.; White, S. D. M.; Helly, J.; Benson, A. J.; De Lucia, G.; Helmi, A.; Jenkins, A.; Navarro, J. F.; Springel, V.; Wang, J.

    2010-01-01

    We present six simulations of galactic stellar haloes formed by the tidal disruption of accreted dwarf galaxies in a fully cosmological setting. Our model is based on the Aquarius project, a suite of high-resolution N-body simulations of individual dark matter haloes. We tag subsets of particles in

  4. WFIRST: Surveying galactic halos within 10Mpc

    Science.gov (United States)

    Courtney, Sol; Johnston, Kathryn; Sanderson, Robyn; WINGS Team

    2018-01-01

    Three aims of a WFIRST Infrared Nearby Galaxy Survey (WINGS) of stellar halos are: (i) to look at the global properties of the halos (e.g. radial profile and total content); (ii) to find and interpret structures that are signatures of accretion histories (including luminosity functions, merger rates and orbits); (iii) to find features at widest possible separations in order to constrain the distribution of dark matter. For all of the above purposes, the halos should be observed to the greatest radial extent possible. The extent to which this is possible or interesting will depend on expected densities of the stellar halos as well as contamination by background galaxies at faint magnitudes. This study “observes" the Bullock/Johnston stellar halo models as a guide for these expectations.

  5. Halo assembly bias and the tidal anisotropy of the local halo environment

    Science.gov (United States)

    Paranjape, Aseem; Hahn, Oliver; Sheth, Ravi K.

    2018-02-01

    We study the role of the local tidal environment in determining the assembly bias of dark matter haloes. Previous results suggest that the anisotropy of a halo's environment (i.e, whether it lies in a filament or in a more isotropic region) can play a significant role in determining the eventual mass and age of the halo. We statistically isolate this effect using correlations between the large-scale and small-scale environments of simulated haloes at z = 0 with masses between 1011.6 ≲ (m/h-1M⊙) ≲ 1014.9. We probe the large-scale environment using a novel halo-by-halo estimator of linear bias. For the small-scale environment, we identify a variable αR that captures the tidal anisotropy in a region of radius R = 4R200b around the halo and correlates strongly with halo bias at fixed mass. Segregating haloes by αR reveals two distinct populations. Haloes in highly isotropic local environments (αR ≲ 0.2) behave as expected from the simplest, spherically averaged analytical models of structure formation, showing a negative correlation between their concentration and large-scale bias at all masses. In contrast, haloes in anisotropic, filament-like environments (αR ≳ 0.5) tend to show a positive correlation between bias and concentration at any mass. Our multi-scale analysis cleanly demonstrates how the overall assembly bias trend across halo mass emerges as an average over these different halo populations, and provides valuable insights towards building analytical models that correctly incorporate assembly bias. We also discuss potential implications for the nature and detectability of galaxy assembly bias.

  6. Dark matter haloes: a multistream view

    Science.gov (United States)

    Ramachandra, Nesar S.; Shandarin, Sergei F.

    2017-09-01

    Mysterious dark matter constitutes about 85 per cent of all masses in the Universe. Clustering of dark matter plays a dominant role in the formation of all observed structures on scales from a fraction to a few hundreds of Mega-parsecs. Galaxies play a role of lights illuminating these structures so they can be observed. The observations in the last several decades have unveiled opulent geometry of these structures currently known as the cosmic web. Haloes are the highest concentrations of dark matter and host luminous galaxies. Currently the most accurate modelling of dark matter haloes is achieved in cosmological N-body simulations. Identifying the haloes from the distribution of particles in N-body simulations is one of the problems attracting both considerable interest and efforts. We propose a novel framework for detecting potential dark matter haloes using the field unique for dark matter-multistream field. The multistream field emerges at the non-linear stage of the growth of perturbations because the dark matter is collisionless. Counting the number of velocity streams in gravitational collapses supplements our knowledge of spatial clustering. We assume that the virialized haloes have convex boundaries. Closed and convex regions of the multistream field are hence isolated by imposing a positivity condition on all three eigenvalues of the Hessian estimated on the smoothed multistream field. In a single-scale analysis of high multistream field resolution and low softening length, the halo substructures with local multistream maxima are isolated as individual halo sites.

  7. Effective field theory description of halo nuclei

    Science.gov (United States)

    Hammer, H.-W.; Ji, C.; Phillips, D. R.

    2017-10-01

    Nuclear halos emerge as new degrees of freedom near the neutron and proton driplines. They consist of a core and one or a few nucleons which spend most of their time in the classically-forbidden region outside the range of the interaction. Individual nucleons inside the core are thus unresolved in the halo configuration, and the low-energy effective interactions are short-range forces between the core and the valence nucleons. Similar phenomena occur in clusters of 4He atoms, cold atomic gases near a Feshbach resonance, and some exotic hadrons. In these weakly-bound quantum systems universal scaling laws for s-wave binding emerge that are independent of the details of the interaction. Effective field theory (EFT) exposes these correlations and permits the calculation of non-universal corrections to them due to short-distance effects, as well as the extension of these ideas to systems involving the Coulomb interaction and/or binding in higher angular-momentum channels. Halo nuclei exhibit all these features. Halo EFT, the EFT for halo nuclei, has been used to compute the properties of single-neutron, two-neutron, and single-proton halos of s-wave and p-wave type. This review summarizes these results for halo binding energies, radii, Coulomb dissociation, and radiative capture, as well as the connection of these properties to scattering parameters, thereby elucidating the universal correlations between all these observables. We also discuss how Halo EFT's encoding of the long-distance physics of halo nuclei can be used to check and extend ab initio calculations that include detailed modeling of their short-distance dynamics.

  8. Degradation of HaloTag-fused nuclear proteins using bestatin-HaloTag ligand hybrid molecules.

    Science.gov (United States)

    Tomoshige, Shusuke; Naito, Mikihiko; Hashimoto, Yuichi; Ishikawa, Minoru

    2015-10-14

    We have developed a protein knockdown technology using hybrid small molecules designed as conjugates of a ligand for the target protein and a ligand for ubiquitin ligase cellular inhibitor of apoptosis protein 1 (cIAP1). However, this technology has several limitations. Here, we report the development of a novel protein knockdown system to address these limitations. In this system, target proteins are fused with HaloTag to provide a common binding site for a degradation inducer. We designed and synthesized small molecules consisting of alkyl chloride as the HaloTag-binding degradation inducer, which binds to HaloTag, linked to BE04 (2), which binds to cIAP1. Using this system, we successfully knocked down HaloTag-fused cAMP responsive element binding protein 1 (HaloTag-CREB1) and HaloTag-fused c-jun (HaloTag-c-jun), which are ligand-unknown nuclear proteins, in living cells. HaloTag-binding degradation inducers can be synthesized easily, and are expected to be useful as biological tools for pan-degradation of HaloTag-fused proteins.

  9. The Dark Halo of the Milky Way

    National Research Council Canada - National Science Library

    Charles Alcock

    2000-01-01

    .... This dark matter is distributed in space differently than the stars, forming a vast, diffuse halo, more spherical than disklike, which occupies more than 1000 times the volume of the disk of stars...

  10. Exact Relativistic Magnetized Haloes around Rotating Disks

    Directory of Open Access Journals (Sweden)

    Antonio C. Gutiérrez-Piñeres

    2015-01-01

    Full Text Available The study of the dynamics of magnetic fields in galaxies is one of important problems in formation and evolution of galaxies. In this paper, we present the exact relativistic treatment of a rotating disk surrounded by a magnetized material halo. The features of the halo and disk are described by the distributional energy-momentum tensor of a general fluid in canonical form. All the relevant quantities and the metric and electromagnetic potentials are exactly determined by an arbitrary harmonic function only. For instance, the generalized Kuzmin-disk potential is used. The particular class of solutions obtained is asymptotically flat and satisfies all the energy conditions. Moreover, the motion of a charged particle on the halo is described. As far as we know, this is the first relativistic model describing analytically the magnetized halo of a rotating disk.

  11. Simulating rainbows and halos in color.

    Science.gov (United States)

    Gedzelman, S D

    1994-07-20

    Geometric optics rainbows and ice-crystal halos that include some effects of a Rayleigh-scattering atmosphere and a cloud of finite optical thickness are simulated in color by the use of a Monte Carlo approach.

  12. Spatial Clustering of Dark Matter Haloes: Secondary Bias, Neighbour Bias, and the Influence of Massive Neighbours on Halo Properties

    Science.gov (United States)

    Salcedo, Andrés N.; Maller, Ariyeh H.; Berlind, Andreas A.; Sinha, Manodeep; McBride, Cameron K.; Behroozi, Peter S.; Wechsler, Risa H.; Weinberg, David H.

    2018-01-01

    We explore the phenomenon commonly known as halo assembly bias, whereby dark matter haloes of the same mass are found to be more or less clustered when a second halo property is considered, for haloes in the mass range 3.7 × 1011 h-1 M⊙ - 5.0 × 1013 h-1 M⊙. Using the Large Suite of Dark Matter Simulations (LasDamas) we consider nine commonly used halo properties and find that a clustering bias exists if haloes are binned by mass or by any other halo property. This secondary bias implies that no single halo property encompasses all the spatial clustering information of the halo population. The mean values of some halo properties depend on their halo's distance to a more massive neighbour. Halo samples selected by having high values of one of these properties therefore inherit a neighbour bias such that they are much more likely to be close to a much more massive neighbour. This neighbour bias largely accounts for the secondary bias seen in haloes binned by mass and split by concentration or age. However, haloes binned by other mass-like properties still show a secondary bias even when the neighbour bias is removed. The secondary bias of haloes selected by their spin behaves differently than that for other halo properties, suggesting that the origin of the spin bias is different than of other secondary biases.

  13. MODIFIED GRAVITY SPINS UP GALACTIC HALOS

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jounghun [Astronomy Program, Department of Physics and Astronomy, FPRD, Seoul National University, Seoul 151-747 (Korea, Republic of); Zhao, Gong-Bo [National Astronomy Observatories, Chinese Academy of Science, Beijing 100012 (China); Li, Baojiu [Institute of Computational Cosmology, Department of Physics, Durham University, Durham DH1 3LE (United Kingdom); Koyama, Kazuya, E-mail: jounghun@astro.snu.ac.kr [Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth, PO1 3FX (United Kingdom)

    2013-01-20

    We investigate the effect of modified gravity on the specific angular momentum of galactic halos by analyzing the halo catalogs at z = 0 from high-resolution N-body simulations for a f(R) gravity model that meets the solar-system constraint. It is shown that the galactic halos in the f(R) gravity model tend to acquire significantly higher specific angular momentum than those in the standard {Lambda}CDM model. The largest difference in the specific angular momentum distribution between these two models occurs for the case of isolated galactic halos with mass less than 10{sup 11} h {sup -1} M {sub Sun }, which are likely least shielded by the chameleon screening mechanism. As the specific angular momentum of galactic halos is rather insensitive to other cosmological parameters, it can in principle be an independent discriminator of modified gravity. We speculate a possibility of using the relative abundance of low surface brightness galaxies (LSBGs) as a test of general relativity given that the formation of the LSBGs occurs in fast spinning dark halos.

  14. Nanomechanics of HaloTag tethers.

    Science.gov (United States)

    Popa, Ionel; Berkovich, Ronen; Alegre-Cebollada, Jorge; Badilla, Carmen L; Rivas-Pardo, Jaime Andrés; Taniguchi, Yukinori; Kawakami, Masaru; Fernandez, Julio M

    2013-08-28

    The active site of the Haloalkane Dehydrogenase (HaloTag) enzyme can be covalently attached to a chloroalkane ligand providing a mechanically strong tether, resistant to large pulling forces. Here we demonstrate the covalent tethering of protein L and I27 polyproteins between an atomic force microscopy (AFM) cantilever and a glass surface using HaloTag anchoring at one end and thiol chemistry at the other end. Covalent tethering is unambiguously confirmed by the observation of full length polyprotein unfolding, combined with high detachment forces that range up to ∼2000 pN. We use these covalently anchored polyproteins to study the remarkable mechanical properties of HaloTag proteins. We show that the force that triggers unfolding of the HaloTag protein exhibits a 4-fold increase, from 131 to 491 pN, when the direction of the applied force is changed from the C-terminus to the N-terminus. Force-clamp experiments reveal that unfolding of the HaloTag protein is twice as sensitive to pulling force compared to protein L and refolds at a slower rate. We show how these properties allow for the long-term observation of protein folding-unfolding cycles at high forces, without interference from the HaloTag tether.

  15. New views of the distant stellar halo

    Science.gov (United States)

    Sanderson, Robyn E.; Secunda, Amy; Johnston, Kathryn V.; Bochanski, John J.

    2017-10-01

    Currently, only a small number of Milky Way (MW) stars are known to exist beyond 100 kpc from the Galactic Centre. Though the distribution of these stars in the outer halo is believed to be sparse, they can provide evidence of more recent accretion events than in the inner halo and help map out the MW's dark matter halo to its virial radius. We have re-examined the outermost regions of 11 existing stellar halo models with two synthetic surveys: one mimicking present-day searches for distant M giants and another mimicking RR Lyra (RRL) projections for the Large Synoptic Survey Telescope (LSST). Our models suggest that colour and proper motion cuts currently used to select M giant candidates for follow-up successfully remove nearly all self-contamination from foreground halo dwarf stars and are useful for focusing observations on distant M giants, of which there are thousands to tens of thousands beyond 100 kpc in our models. We likewise expect that LSST will identify comparable numbers of RRLe at these distances. We demonstrate that several observable properties of both tracers, such as proximity of neighbouring stars, proper motions and distances (for RRLe), could help us separate different accreted dwarf galaxies from one another in the distant MW halo. We also discuss prospects for using ratios of M giants to RRLe as a proxy for accretion time, which in the future could provide new constraints on the recent accretion history of our Galaxy.

  16. RR Lyrae to understand the Galactic halo

    Science.gov (United States)

    Fiorentino, Giuliana

    2016-08-01

    We present recent results obtained using old variable RR Lyrae stars on the Galactic halo structure and its connection with nearby dwarf galaxies. We compare the period and period-amplitude distributions for a sizeable sample of fundamental mode RR Lyrae stars (RRab) in dwarf spheroidals (~1300 stars) with those in the Galactic halo (~16'000 stars) and globular clusters (~1000 stars). RRab in dwarfs -as observed today- do not appear to follow the pulsation properties shown by those in the Galactic halo, nor they have the same properties as RRab in globulars. Thanks to the OGLE experiment we extended our comparison to massive metal-rich satellites like the dwarf irregular Large Magellanic Cloud (LMC) and the Sagittarius (Sgr) dwarf spheroidal. These massive and more metal-rich stellar systems likely have contributed to the Galactic halo formation more than classical dwarf spheroidals. Finally, exploiting the intrinsic nature of RR Lyrae as distance indicators we were able to study the period and period amplitude distributions of RRab within the Halo. It turned out that the inner and the outer Halo do show a difference that may suggest a different formation scenario (in situ vs accreted).

  17. Statistics of dark matter substructure - III. Halo-to-halo variance

    Science.gov (United States)

    Jiang, Fangzhou; van den Bosch, Frank C.

    2017-11-01

    We present a study of unprecedented statistical power regarding the halo-to-halo variance of dark matter substructure. Combining N-body simulations and a semi-analytical model, we investigate the variance in subhalo mass fractions and occupation numbers, with an emphasis on their halo-formation-time dependence. We show that the average subhalo mass fraction, fsub, is mainly a function of halo formation time: at fixed formation redshift, the average subhalo mass fraction is virtually independent of halo mass and the mass dependence of fsub therefore mainly manifests the later assembly of more massive haloes. We note that the observational constraints on fsub from gravitational lensing are substantially higher than the median Λcold dark matter predictions, yet marginally lie within the 95th percentile when the halo-to-halo variance is considered. The halo occupation number distribution of subhaloes, P(Nsub|Mhalo), in addition to the well-known super-Poissonity for large 〈Nsub〉, is sub-Poissonian for 〈Nsub〉 ≲ 2. Ignoring this results in systematic errors of the predicted clustering of galaxies of a few percent, with a complicated scale- and luminosity dependence. The non-Poissonity is likely imprinted at accretion, and the dynamical evolution of subhaloes drives the statistics towards Poissonian. Contrary to a recent claim, the non-Poissonity of subhalo occupation statistics does not vanish by selecting haloes with fixed mass and fixed formation redshift. Finally, we use subhalo occupation statistics to put loose constraints on the mass and formation redshift of the Milky Way halo.

  18. Simulating Halos with the Caterpillar Project

    Science.gov (United States)

    Kohler, Susanna

    2016-04-01

    The Caterpillar Project is a beautiful series of high-resolution cosmological simulations. The goal of this project is to examine the evolution of dark-matter halos like the Milky Ways, to learn about how galaxies like ours formed. This immense computational project is still in progress, but the Caterpillar team is already providing a look at some of its first results.Lessons from Dark-Matter HalosWhy simulate the dark-matter halos of galaxies? Observationally, the formation history of our galaxy is encoded in galactic fossil record clues, like the tidal debris from disrupted satellite galaxies in the outer reaches of our galaxy, or chemical abundance patterns throughout our galactic disk and stellar halo.But to interpret this information in a way that lets us learn about our galaxys history, we need to first test galaxy formation and evolution scenarios via cosmological simulations. Then we can compare the end result of these simulations to what we observe today.This figure illustrates the difference that mass resolution makes. In the left panel, the mass resolution is 1.5*10^7 solar masses per particle. In the right panel, the mass resolution is 3*10^4 solar masses per particle [Griffen et al. 2016]A Computational ChallengeDue to how computationally expensive such simulations are, previous N-body simulations of the growth of Milky-Way-like halos have consisted of only one or a few halos each. But in order to establish a statistical understanding of how galaxy halos form and find out whether the Milky Ways halo is typical or unusual! it is necessary to simulate a larger number of halos.In addition, in order to accurately follow the formation and evolution of substructure within the dark-matter halos, these simulations must be able to resolve the smallest dwarf galaxies, which are around a million solar masses. This requires an extremely high mass resolution, which adds to the computational expense of the simulation.First OutcomesThese are the challenges faced by

  19. Linking dwarf galaxies to halo building blocks with the most metal-poor star in Sculptor.

    Science.gov (United States)

    Frebel, Anna; Kirby, Evan N; Simon, Joshua D

    2010-03-04

    Current cosmological models indicate that the Milky Way's stellar halo was assembled from many smaller systems. On the basis of the apparent absence of the most metal-poor stars in present-day dwarf galaxies, recent studies claimed that the true Galactic building blocks must have been vastly different from the surviving dwarfs. The discovery of an extremely iron-poor star (S1020549) in the Sculptor dwarf galaxy based on a medium-resolution spectrum cast some doubt on this conclusion. Verification of the iron-deficiency, however, and measurements of additional elements, such as the alpha-element Mg, are necessary to demonstrate that the same type of stars produced the metals found in dwarf galaxies and the Galactic halo. Only then can dwarf galaxy stars be conclusively linked to early stellar halo assembly. Here we report high-resolution spectroscopic abundances for 11 elements in S1020549, confirming its iron abundance of less than 1/4,000th that of the Sun, and showing that the overall abundance pattern follows that seen in low-metallicity halo stars, including the alpha-elements. Such chemical similarity indicates that the systems destroyed to form the halo billions of years ago were not fundamentally different from the progenitors of present-day dwarfs, and suggests that the early chemical enrichment of all galaxies may be nearly identical.

  20. Gravitationally Consistent Halo Catalogs and Merger Trees for Precision Cosmology

    Science.gov (United States)

    Behroozi, Peter S.; Wechsler, Risa H.; Wu, Hao-Yi; Busha, Michael T.; Klypin, Anatoly A.; Primack, Joel R.

    2013-01-01

    We present a new algorithm for generating merger trees and halo catalogs which explicitly ensures consistency of halo properties (mass, position, and velocity) across time steps. Our algorithm has demonstrated the ability to improve both the completeness (through detecting and inserting otherwise missing halos) and purity (through detecting and removing spurious objects) of both merger trees and halo catalogs. In addition, our method is able to robustly measure the self-consistency of halo finders; it is the first to directly measure the uncertainties in halo positions, halo velocities, and the halo mass function for a given halo finder based on consistency between snapshots in cosmological simulations. We use this algorithm to generate merger trees for two large simulations (Bolshoi and Consuelo) and evaluate two halo finders (ROCKSTAR and BDM). We find that both the ROCKSTAR and BDM halo finders track halos extremely well; in both, the number of halos which do not have physically consistent progenitors is at the 1%-2% level across all halo masses. Our code is publicly available at http://code.google.com/p/consistent-trees. Our trees and catalogs are publicly available at http://hipacc.ucsc.edu/Bolshoi/.

  1. Revealing the Cosmic Web-dependent Halo Bias

    Science.gov (United States)

    Yang, Xiaohu; Zhang, Youcai; Lu, Tianhuan; Wang, Huiyuan; Shi, Feng; Tweed, Dylan; Li, Shijie; Luo, Wentao; Lu, Yi; Yang, Lei

    2017-10-01

    Halo bias is the one of the key ingredients of the halo models. It was shown at a given redshift to be only dependent, to the first order, on the halo mass. In this study, four types of cosmic web environments—clusters, filaments, sheets, and voids—are defined within a state-of-the-art high-resolution N-body simulation. Within these environments, we use both halo-dark matter cross correlation and halo-halo autocorrelation functions to probe the clustering properties of halos. The nature of the halo bias differs strongly between the four different cosmic web environments described here. With respect to the overall population, halos in clusters have significantly lower biases in the {10}11.0˜ {10}13.5 {h}-1 {M}⊙ mass range. In other environments, however, halos show extremely enhanced biases up to a factor 10 in voids for halos of mass ˜ {10}12.0 {h}-1 {M}⊙ . Such a strong cosmic web environment dependence in the halo bias may play an important role in future cosmological and galaxy formation studies. Within this cosmic web framework, the age dependency of halo bias is found to be only significant in clusters and filaments for relatively small halos ≲ {10}12.5 {h}-1 {M}⊙ .

  2. Electric Properties of One-Neutron Halo Nuclei in Halo EFT

    Science.gov (United States)

    Braun, Jonas; Hammer, Hans-Werner

    2017-03-01

    We exploit the separation of scales in weakly-bound nuclei to compute E2 transitions and electric form factors in a halo effective field theory (EFT) framework. The relevant degrees of freedom are the core and the halo neutron. The EFT expansion is carried out in powers of R_{core}/R_{halo}, where R_{core} and R_{halo} denote the length scales of the core and halo, respectively. We include the strong s-wave and d-wave interactions by introducing dimer fields. The dimer propagators are regulated by employing the power divergence subtraction scheme and matched to the effective range expansion in the respective channel. Electromagnetic interactions are included via minimal substitution in the Lagrangian. We demonstrate that, depending on the observable and respective partial wave, additional local gauge-invariant operators contribute in LO, NLO and higher orders.

  3. Dependence of halo bias on mass and environment

    Science.gov (United States)

    Shi, Jingjing; Sheth, Ravi K.

    2018-01-01

    The simplest analyses of halo bias assume that halo mass alone determines halo clustering. However, if the large-scale environment is fixed, then halo clustering is almost entirely determined by environment, and is almost completely independent of halo mass. We show why. Our analysis is useful for studies that use the environmental dependence of clustering to constrain cosmological and galaxy formation models. It also shows why many correlations between galaxy properties and environment are merely consequences of the underlying correlations between haloes and their environments, and provides a framework for quantifying such inherited correlations.

  4. One-proton halo in sup 3 sup 1 Cl with relativistic mean-field theory

    CERN Document Server

    Cai Xiang Zhou; Jiang Wei; Fang De Qing; Zhang Hu Yong; Zhong Chen; Wei Yi Bin; Guo Wei; Ma Yu Gang; Zhu Zhi Yuan; Ren Zhong Zhou

    2002-01-01

    The authors investigate proton-rich isotopes sup 3 sup 1 sup , sup 3 sup 2 Cl using the nonlinear relativistic mean-field model. It is shown that this model can reproduce the properties of these nuclei well. A long tail appears in the calculated proton density distribution of sup 3 sup 1 Cl. The results of relativistic density-dependent Hartree theory show a similar trend of tail density distribution. It is strongly suggested that there is a proton halo in sup 3 sup 1 Cl and it is indicated that there may be a proton skin in sup 3 sup 2 Cl. The relation between the proton halo in sup 3 sup 1 Cl and the new proton magic number is discussed

  5. Stability of BEC galactic dark matter halos

    Energy Technology Data Exchange (ETDEWEB)

    Guzmán, F.S.; Lora-Clavijo, F.D.; González-Avilés, J.J.; Rivera-Paleo, F.J., E-mail: guzman@ifm.umich.mx, E-mail: fadulora@ifm.umich.mx, E-mail: javiles@ifm.umich.mx, E-mail: friverap@ifm.umich.mx [Instituto de Física y Matemáticas, Universidad Michoacana de San Nicolás de Hidalgo, Edificio C-3, Cd. Universitaria, 58040 Morelia, Michoacán (Mexico)

    2013-09-01

    In this paper we show that spherically symmetric BEC dark matter halos, with the sin r/r density profile, that accurately fit galactic rotation curves and represent a potential solution to the cusp-core problem are unstable. We do this by introducing back the density profiles into the fully time-dependent Gross-Pitaevskii-Poisson system of equations. Using numerical methods to track the evolution of the system, we found that these galactic halos lose mass at an approximate rate of half of its mass in a time scale of dozens of Myr. We consider this time scale is enough as to consider these halos are unstable and unlikely to be formed. We provide some arguments to show that this behavior is general and discuss some other drawbacks of the model that restrict its viability.

  6. The dark halo of the Milky Way.

    Science.gov (United States)

    Alcock, C.

    2000-01-01

    Most of the matter in the Milky Way is invisible to astronomers. Precise numbers are elusive, but it appears that the dark component is 20 times as massive as the visible disk of stars and gas. This dark matter is distributed in space differently than the stars, forming a vast, diffuse halo, more spherical than disklike, which occupies more than 1000 times the volume of the disk of stars. The composition of this dark halo is unknown, but it may comprise a mixture of ancient, degenerate dwarf stars and exotic, hypothetical elementary particles.

  7. Complex artificial halos for the classroom

    Science.gov (United States)

    Selmke, Markus; Selmke, Sarah

    2016-07-01

    Halos represent a common and imposing atmospheric optics phenomenon whose displays are caused by tiny air-borne ice crystals. Their variety stems from a certain set of orientation classes to which these crystals belong. We present a robust and inexpensive device, made of modular components, that allows for the replication of most of these orientation classes in the laboratory. Under the illumination of light, the corresponding artificial halo counterparts emerge. The mechanical realization of this device allows a thorough understanding and demonstration of these beautiful atmospheric optics phenomena.

  8. Dark energy and extended dark matter halos

    Science.gov (United States)

    Chernin, A. D.; Teerikorpi, P.; Valtonen, M. J.; Dolgachev, V. P.; Domozhilova, L. M.; Byrd, G. G.

    2012-03-01

    The cosmological mean matter (dark and baryonic) density measured in the units of the critical density is Ωm = 0.27. Independently, the local mean density is estimated to be Ωloc = 0.08-0.23 from recent data on galaxy groups at redshifts up to z = 0.01-0.03 (as published by Crook et al. 2007, ApJ, 655, 790 and Makarov & Karachentsev 2011, MNRAS, 412, 2498). If the lower values of Ωloc are reliable, as Makarov & Karachentsev and some other observers prefer, does this mean that the Local Universe of 100-300 Mpc across is an underdensity in the cosmic matter distribution? Or could it nevertheless be representative of the mean cosmic density or even be an overdensity due to the Local Supercluster therein. We focus on dark matter halos of groups of galaxies and check how much dark mass the invisible outer layers of the halos are able to host. The outer layers are usually devoid of bright galaxies and cannot be seen at large distances. The key factor which bounds the size of an isolated halo is the local antigravity produced by the omnipresent background of dark energy. A gravitationally bound halo does not extend beyond the zero-gravity surface where the gravity of matter and the antigravity of dark energy balance, thus defining a natural upper size of a system. We use our theory of local dynamical effects of dark energy to estimate the maximal sizes and masses of the extended dark halos. Using data from three recent catalogs of galaxy groups, we show that the calculated mass bounds conform with the assumption that a significant amount of dark matter is located in the invisible outer parts of the extended halos, sufficient to fill the gap between the observed and expected local matter density. Nearby groups of galaxies and the Virgo cluster have dark halos which seem to extend up to their zero-gravity surfaces. If the extended halo is a common feature of gravitationally bound systems on scales of galaxy groups and clusters, the Local Universe could be typical or even

  9. Matter radii of light proton-rich and neutron-rich nuclear isotopes

    Science.gov (United States)

    Ahmad, Suhel; Usmani, A. A.; Khan, Z. A.

    2017-12-01

    We extract the matter root-mean-square (rms) radii of a wide range of light proton and neutron rich nuclear isotopes (He-Mg) by studying their interaction cross sections (σI) on 12C at intermediate energies within the framework of the Glauber model. The calculations involve the nucleon densities obtained from harmonic-oscillator Slater determinants. The matter rms radii so obtained are compared with those available in the literature. It is demonstrated that the present description of matter densities can be conveniently used to explain the experimental values of σI, and the extracted matter rms radii may be considered an indication of the presence of halos and skins in proton- and neutron-rich nuclei.

  10. One-proton halo in 26P and two-proton halo in 27S

    Science.gov (United States)

    Ren, Zhongzhou; Chen, Baoqiu; Ma, Zhongyu; Xu, Gongou

    1996-02-01

    Proton-drip-line nuclei 26P and 27S are studied in the nonlinear relativistic mean-field theory. Calculations show that the mean-square radius of protons in the 2s1/2 state is approximately 18-20 fm2 which is abnormally large as compared with the mean-square radii of proton, neutron, and matter distributions, giving a strong evidence for proton halos in 26P and 27S. This indicates that the size of proton halos is as large as that of neutron halos although there exists the Coulomb barrier in proton-drip-line nuclei.

  11. Substructure in the Stellar Halos of the Aquarius Simulations

    NARCIS (Netherlands)

    Helmi, Amina; Cooper, A. P.; White, S. D. M.; Cole, S.; Frenk, C. S.; Navarro, J. F.

    2011-01-01

    We characterize the substructure in the simulated stellar halos of Cooper et al. which were formed by the disruption of satellite galaxies within the cosmological N-body simulations of galactic halos of the Aquarius project. These stellar halos exhibit a wealth of tidal features: broad overdensities

  12. Halo white dwarfs in the Gaia era

    NARCIS (Netherlands)

    van Oirschot, P.; Nelemans, G.; Pols, O.; Helmi, A.; Tolstoy, E.; Brown, A. G. A.; Pugliese, G.; de Koter, A.; Wijburg, M.

    The Galactic Halo is the oldest and most metal-poor component of the Galaxy. It is studied in detail both to understand the formation and evolution of galaxies, as well as the formation and evolution of the earliest stars. With this aim in mind, we plan to couple a population synthesis model to a

  13. New (theoretical) Perspectives on the Galactic Halo

    NARCIS (Netherlands)

    Helmi, A.; Turon, C; Meynadier, F; Arenou, F

    1 discuss recent progress in our understanding of the formation of the stellar halo of the Milky Way in the context of the concordance cosmological model. The Gaia mission will provide unique insights especially into the early assembly of the Galaxy and likely be key in unraveling its merger

  14. Reflection halo twins : subsun and supersun

    NARCIS (Netherlands)

    Konnen, Gunther P.; van der Werf, Siebren Y.

    2011-01-01

    From an aircraft, a short distinct vertical structure is sometimes seen above the setting sun. Such a feature can be understood as a halo, which is the counterpart of the well-known subsun. Whereas the latter arises from reflections off basal faces of plate-oriented ice crystals illuminated from

  15. Streams in the Aquarius stellar haloes

    NARCIS (Netherlands)

    Gomez, Facundo A.; Helmi, Amina; Cooper, Andrew P.; Frenk, Carlos S.; Navarro, Julio F.; White, Simon D. M.

    2013-01-01

    We use the very high resolution, fully cosmological simulations from the Aquarius Project, coupled to a semi-analytical model of galaxy formation, to study the phase-space distribution of halo stars in 'solar neighbourhood' like volumes. We find that this distribution is very rich in substructure in

  16. The Impact of Theoretical Uncertainties in the Halo Mass Function and Halo

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Hao-Yi; Zentner, Andrew R.; Wechsler, Risa H.; /KIPAC, Menlo Park /SLAC /Pittsburgh U. /KIPAC, Menlo Park /SLAC

    2010-06-04

    We study the impact of theoretical uncertainty in the dark matter halo mass function and halo bias on dark energy constraints from imminent galaxy cluster surveys. We find that for an optical cluster survey like the Dark Energy Survey, the accuracy required on the predicted halo mass function to make it an insignificant source of error on dark energy parameters is {approx}1%. The analogous requirement on the predicted halo bias is less stringent ({approx}5%), particularly if the observable-mass distribution can be well constrained by other means. These requirements depend upon survey area but are relatively insensitive to survey depth. The most stringent requirements are likely to come from a survey over a significant fraction of the sky that aims to observe clusters down to relatively low mass, M{sub th}{approx} 10{sup 13.7} h{sup -1} M{sub sun}; for such a survey, the mass function and halo bias must be predicted to accuracies of {approx}0.5% and {approx}1%, respectively. These accuracies represent a limit on the practical need to calibrate ever more accurate halo mass and bias functions. We find that improving predictions for the mass function in the low-redshift and low-mass regimes is the most effective way to improve dark energy constraints.

  17. Parametrizing the stellar haloes of galaxies

    Science.gov (United States)

    D'Souza, Richard; Kauffman, Guinevere; Wang, Jing; Vegetti, Simona

    2014-09-01

    We study the stellar haloes of galaxies out to 70-100 kpc as a function of stellar mass and galaxy type by stacking aligned r- and g-band images from a sample of 45 508 galaxies from Sloan Digital Sky Survey Data Release 9 in the redshift range 0.06 ≤ z ≤ 0.1 and in the mass range 1010.0 M⊙ < M* < 1011.4 M⊙. We derive surface brightness profiles to a depth of almost μr ˜ 32 mag arcsec-2. We find that the ellipticity of the stellar halo is a function of galaxy stellar mass and that the haloes of high-concentration galaxies are more elliptical than those of low-concentration galaxies. Where the g - r colour of the stellar halo can be measured, we find that the stellar light is always bluer than in the main galaxy. The colour of the stellar halo is redder for more massive galaxies. We further demonstrate that the full two-dimensional surface intensity distribution of our galaxy stacks can only be fit through multicomponent Sérsic models. Using the fraction of light in the outer component of the models as a proxy for the fraction of accreted stellar light, we show that this fraction is a function of stellar mass and galaxy type. The fraction of accreted stellar light rises from 30 to 70 per cent and from 2 to 25 per cent for high- and low-concentration galaxies, respectively, over the mass range 1010.0-1011.4 M⊙.

  18. Characteristic time for halo current growth and rotation

    Energy Technology Data Exchange (ETDEWEB)

    Boozer, Allen H., E-mail: ahb17@columbia.edu [Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027 (United States)

    2015-10-15

    A halo current flows for part of its path through the plasma edge and for part through the chamber walls and during tokamak disruptions can be as large as tenths of the plasma current. The primary interest in halo currents is the large force that they can exert on machine components particularly if the toriodal rotation of the halo current resonates with a natural oscillation frequency of the tokamak device. Halo currents arise when required to slow down the growth of a kink that is too unstable to be stabilized by the chamber walls. The width of the current channel in the halo plasma is comparable to the amplitude of the kink, and the halo current grows linearly, not exponentially, in time. The current density in the halo is comparable to that of the main plasma body. The rocket force due to plasma flowing out of the halo and recombining on the chamber walls can cause the non-axisymmetric magnetic structure produced by the kink to rotate toroidally at a speed comparable to the halo speed of sound. Gerhardt's observations of the halo current in NSTX shot 141 687 [Nucl. Fusion 53, 023005 (2013)] illustrate many features of the theory of halo currents and are discussed as a summary of the theory.

  19. Dynamics of the Disruption Halo Current Toroidal Asymmetry in NSTX

    Energy Technology Data Exchange (ETDEWEB)

    S.P. Gerhardt

    2012-09-27

    This paper describes the dynamics of disruption halo current non-axisymmetries in the lower divertor of the National Spherical Torus Experiment [M. Ono, et al. Nuclear Fusion 40, 557 (2000)]. While. The halo currents typically have a strongly asymmetric structure where they enter the divertor floor, and this asymmetry has been observed to complete up to 7 toroidal revolutions over the duration of the halo current pulse. However, the rotation speed and toroidal extend of the asymmetry can vary significantly during the pulse. The rotation speed, halo current pulse duration, and total number of revolutions tend to be smaller in cases with large halo currents. The halo current pattern is observed to become toroidally symmetric at the end of the halo current pulse. It is proposed that this symmeterization is due to the loss of most or all of the closed field line geometry in the final phase of the vertical displacement event.

  20. ORIGAMI: DELINEATING HALOS USING PHASE-SPACE FOLDS

    Energy Technology Data Exchange (ETDEWEB)

    Falck, Bridget L.; Neyrinck, Mark C.; Szalay, Alexander S. [Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States)

    2012-08-01

    We present the ORIGAMI method of identifying structures, particularly halos, in cosmological N-body simulations. Structure formation can be thought of as the folding of an initially flat three-dimensional manifold in six-dimensional phase space. ORIGAMI finds the outer folds that delineate these structures. Halo particles are identified as those that have undergone shell-crossing along three orthogonal axes, providing a dynamical definition of halo regions that is independent of density. ORIGAMI also identifies other morphological structures: particles that have undergone shell-crossing along 2, 1, or 0 orthogonal axes correspond to filaments, walls, and voids, respectively. We compare this method to a standard friends-of-friends halo-finding algorithm and find that ORIGAMI halos are somewhat larger, more diffuse, and less spherical, though the global properties of ORIGAMI halos are in good agreement with other modern halo-finding algorithms.

  1. Using Tidal Tails to Probe Dark Matter Halos

    Science.gov (United States)

    Mihos, Chris; Dubinski, John; Hernquist, Lars

    1995-03-01

    We present a series of numerical simulations of merging galaxies to explore the effect of differing halo mass distributions on the morphology of tidal tails. We employ composite disk/bulge/halo galaxy models which span a range of halo properties from low mass, compact halos to very massive, extended halos, and possess identically flat rotation curves inside a few disk scale lengths. These merger experiments are performed with a range of impact parameters, inclinations and mass ratios for the galaxies as well. Our simulations indicate that even under the most favorable conditions, galaxies with extended dark matter halos produce very anemic tidal tails when merging. In light of several observed mergers which sport prominent tidal tails --- e.g., NGC 7252, NGC 4038/39 (``The Antennae"), NGC 4676, and most spectacularly IRAS 19254-7245 (``The Superantennae") --- our results suggest that galaxy halos may be significantly more compact and less massive than expected in Omega =1 cosmological scenarios.

  2. Precise halo orbit design and optimal transfer to halo orbits from earth using differential evolution

    Science.gov (United States)

    Nath, Pranav; Ramanan, R. V.

    2016-01-01

    The mission design to a halo orbit around the libration points from Earth involves two important steps. In the first step, we design a halo orbit for a specified size and in the second step, we obtain an optimal transfer trajectory design to the halo orbit from an Earth parking orbit. Conventionally, the preliminary design for these steps is obtained using higher order analytical solution and the dynamical systems theory respectively. Refinements of the design are carried out using gradient based methods such as differential correction and pseudo arc length continuation method under the of circular restricted three body model. In this paper, alternative single level schemes are developed for both of these steps based on differential evolution, an evolutionary optimization technique. The differential evolution based scheme for halo orbit design produces precise halo orbit design avoiding the refinement steps. Further, in this approach, prior knowledge of higher order analytical solutions for the halo orbit design is not needed. The differential evolution based scheme for the transfer trajectory, identifies the precise location on the halo orbit that needs minimum energy for insertion and avoids exploration of multiple points. The need of a close guess is removed because the present scheme operates on a set of bounds for the unknowns. The constraint on the closest approach altitude from Earth is handled through objective function. The use of these schemes as the design and analysis tools within the of circular restricted three body model is demonstrated through case studies for missions to the first libration point of Sun-Earth system.

  3. Single-particle and collective motion in unbound deformed 39Mg

    Science.gov (United States)

    Fossez, K.; Rotureau, J.; Michel, N.; Liu, Quan; Nazarewicz, W.

    2016-11-01

    Background: Deformed neutron-rich magnesium isotopes constitute a fascinating territory where the interplay between collective rotation and single-particle motion is strongly affected by the neutron continuum. The unbound f p -shell nucleus 39Mg is an ideal candidate to study this interplay. Purpose: In this work, we predict the properties of low-lying resonant states of 39Mg, using a suite of realistic theoretical approaches rooted in the open quantum system framework. Method: To describe the spectrum and decay modes of 39Mg we use the conventional shell model, Gamow shell model, resonating group method, density matrix renormalization group method, and the nonadiabatic particle-plus-rotor model formulated in the Berggren basis. Results: The unbound ground state of 39Mg is predicted to be either a Jπ=7/2 - state or a 3/2 - state. A narrow Jπ=7/2 - ground-state candidate exhibits a resonant structure reminiscent of that of its one-neutron halo neighbor 37Mg, which is dominated by the f7 /2 partial wave at short distances and a p3 /2 component at large distances. A Jπ=3/2 - ground-state candidate is favored by the large deformation of the system. It can be associated with the 1/2 -[321 ] Nilsson orbital dominated by the ℓ =1 wave; hence its predicted width is large. The excited Jπ=1/2 - and 5 /2- states are expected to be broad resonances, while the Jπ=9/2 - and 11/2 - members of the ground-state rotational band are predicted to have very small neutron decay widths. Conclusion: We demonstrate that the subtle interplay between deformation, shell structure, and continuum coupling can result in a variety of excitations in an unbound nucleus just outside the neutron drip line.

  4. Magnesium isotope fractionation during carbonatite magmatism at Oldoinyo Lengai, Tanzania

    Science.gov (United States)

    Li, Wang-Ye; Teng, Fang-Zhen; Halama, Ralf; Keller, Jörg; Klaudius, Jurgis

    2016-06-01

    To investigate the behaviour of Mg isotopes during carbonatite magmatism, we analyzed Mg isotopic compositions of natrocarbonatites and peralkaline silicate rocks from Oldoinyo Lengai, Tanzania. The olivine melilitites from the vicinity of Oldoinyo Lengai have homogeneous and mantle-like Mg isotopic compositions (δ26Mg of -0.30 to -0.26‰), indicating limited Mg isotope fractionation during mantle melting. The highly evolved peralkaline silicate rocks not related to silicate-carbonatite liquid immiscibility, including phonolites from the unit Lengai I, combeite-wollastonite nephelinites (CWNs) from the unit Lengai II A and carbonated combeite-wollastonite-melilite nephelinites (carbCWMNs), have δ26Mg values (from -0.25 to -0.10‰) clustered around the mantle value. By contrast, the CWNs from the unit Lengai II B, which evolved from the silicate melts that were presumably generated by silicate-carbonatite liquid immiscibility, have heavier Mg isotopes (δ26Mg of -0.06 to +0.09‰). Such a difference suggests Mg isotope fractionation during liquid immiscibility and implies, based on mass-balance calculations, that the original carbonatite melts at Lengai were isotopically light. The variable and positive δ26Mg values of natrocarbonatites (from +0.13 to +0.37‰) hence require a change of their Mg isotopic compositions subsequent to liquid immiscibility. The negative correlations between δ26Mg values and contents of alkali and alkaline earth metals of natrocarbonatites suggest Mg isotope fractionation during fractional crystallization of carbonatite melts, with heavy Mg isotopes enriched in the residual melts relative to fractionated carbonate minerals. Collectively, significant Mg isotope fractionation may occur during both silicate-carbonatite liquid immiscibility and fractional crystallization of carbonatite melts, making Mg isotopes a potentially useful tracer of these processes relevant to carbonatite petrogenesis.

  5. Chemical and isotopic fractionation during the evaporation of the FeO-MgO-SiO 2-CaO-Al 2O 3-TiO 2 rare earth element melt system

    Science.gov (United States)

    Wang, Jianhua; Davis, Andrew M.; Clayton, Robert N.; Mayeda, Toshiko K.; Hashimoto, Akihiko

    2001-02-01

    A synthetic material with solar elemental proportions of iron, magnesium, silicon, titanium, calcium, and aluminum oxides and doped with rare earth elements was evaporated in a vacuum furnace at 1800 and 2000°C for different durations to study its chemical and isotopic evolution during the evaporation process. It is demonstrated that kinetic evaporation of solar composition material can produce residues of calcium-, aluminum-rich inclusion bulk chemistry. The evaporation sequence of the main constituents in this solar composition material is iron > silicon ≈ magnesium > titanium. Calcium and aluminum remain unevaporated after evaporation of 95% of the solar composition material. The chemical fractionation between the gas and condensed phase is a function not only of temperature and pressure, but also of the bulk chemical composition of the condensed phase. During the evaporation process, cerium is almost as volatile as iron. The 2,000-fold cerium depletion found in some refractory inclusions in carbonaceous chondrites was reproduced in the evaporation experiment and can be readily explained as a result of evaporation of preexisting meteoritic material. Kinetic isotopic fractionation of magnesium, oxygen, and silicon follows the Rayleigh distillation law during the laboratory evaporation of synthetic solar composition material. This implies that the residue is well mixed during the evaporation process and that the evaporation kinetic processes (both chemical and isotopic) are surface reaction-controlled. The isotopic mass fractionation factors are lower than those predicted from theoretical calculations by using the square root of mass ratios of likely evaporating species. Thus, the surface reaction is more complicated than decomposition into single gas species of each element.

  6. The Halo B2B Studio

    Science.gov (United States)

    Gorzynski, Mark; Derocher, Mike; Mitchell, April Slayden

    Research underway at Hewlett-Packard on remote communication resulted in the identification of three important components typically missing in existing systems. These missing components are: group nonverbal communication capabilities, high-resolution interactive data capabilities, and global services. Here we discuss some of the design elements in these three areas as part of the Halo program at HP, a remote communication system shown to be effective to end-users.

  7. Nuclear charge radius measurements of radioactive beryllium isotopes

    CERN Multimedia

    2002-01-01

    We propose to measure the nuclear charge radii of the beryllium isotopes $^{7,9,10}$Be and the one-neutron halo isotope $^{11}$Be using laser spectroscopy of trapped ions. Ions produced at ISOLDE and ionized with the laser ion source will be cooled and bunched in the radio-frequency buncher of the ISOLTRAP experiment and then transferred into a specially designed Paul trap. Here, they will be cooled to temperatures in the mK range employing sympathetic and direct laser cooling. Precision laser spectroscopy of the isotope shift on the cooled ensemble in combination with accurate atomic structure calculations will provide nuclear charge radii with a precision of better than 3%. This will be the first model-independent determination of a one-neutron halo nuclear charge radius.

  8. Beam Shape and Halo Monitor Study

    CERN Document Server

    Lallement, J B; Hori, M; CERN. Geneva. AB Department

    2006-01-01

    The Beam Shape and Halo Monitor, designed by Masaki Hori, is the main diagnostic tool for the 3 MeV test stand scheduled in 2008. This detector will be able to measure the transverse halo generated in the RFQ and the Chopper-line and to detect and measure the longitudinal halo composed of the incompletely chopped bunches. Its principle of functioning is the following: H- ions hit a carbon foil and generate secondary electrons with the same spatial distribution than the incoming beam and a current depending on an emission coefficient given by the carbon foil. These electrons are accelerated towards a phosphor screen by an electric field applied between accelerating grids. Once the electrons reach the phosphor screen, they generate light which is transmitted to a CCD camera via optic fibers [1]. It is expected to give a time resolution of 1-2ns and a spatial resolution of 1mm. The first test of the BSHM done with a Laser has shown a spatial resolution bigger than 1cm and the time resolution bigger than 2ns[2]. ...

  9. Dissecting Halo Components in IFU Data

    Directory of Open Access Journals (Sweden)

    Michael Merrifield

    2017-05-01

    Full Text Available While most astronomers are now familiar with tools to decompose images into multiple components such as disks, bulges, and halos, the equivalent techniques for spectral data cubes are still in their infancy. This is unfortunate, as integral field unit (IFU spectral surveys are now producing a mass of data in this format, which we are ill-prepared to analyze effectively. We have therefore been developing new tools to separate out components using this full spectral data. The results of such analyses will prove invaluable in determining not only whether such decompositions have an astrophysical significance, but, where they do, also in determining the relationship between the various elements of a galaxy. Application to a pilot study of IFU data from the cD galaxy NGC 3311 confirms that the technique can separate the stellar halo from the underlying galaxy in such systems, and indicates that, in this case, the halo is older and more metal poor than the galaxy, consistent with it forming from the cannibalism of smaller satellite galaxies. The success of the method bodes well for its application to studying the larger samples of cD galaxies that IFU surveys are currently producing.

  10. The Extended Baryonic Halo of NGC 3923

    Directory of Open Access Journals (Sweden)

    Bryan W. Miller

    2017-07-01

    Full Text Available Galaxy halos and their globular cluster systems build up over time by the accretion of small satellites. We can learn about this process in detail by observing systems with ongoing accretion events and comparing the data with simulations. Elliptical shell galaxies are systems that are thought to be due to ongoing or recent minor mergers. We present preliminary results of an investigation of the baryonic halo—light profile, globular clusters, and shells/streams—of the shell galaxy NGC 3923 from deep Dark Energy Camera (DECam g and i-band imaging. We present the 2D and radial distributions of the globular cluster candidates out to a projected radius of about 185 kpc, or ∼ 37 R e , making this one of the most extended cluster systems studied. The total number of clusters implies a halo mass of M h ∼ 3 × 10 13 M ⊙ . Previous studies had identified between 22 and 42 shells, making NGC 3923 the system with the largest number of shells. We identify 23 strong shells and 11 that are uncertain. Future work will measure the halo mass and mass profile from the radial distributions of the shell, N-body models, and line-of-sight velocity distribution (LOSVD measurements of the shells using the Multi Unit Spectroscopic Explorer (MUSE.

  11. Two-proton radioactivity with 2p halo in light mass nuclei A=18–34

    Directory of Open Access Journals (Sweden)

    G. Saxena

    2017-12-01

    Full Text Available Two-proton radioactivity with 2p halo is reported theoretically in light mass nuclei A=18–34. We predict 19Mg, 22Si, 26S, 30Ar and 34Ca as promising candidates of ground state 2p-radioactivity with S2p0. Observation of extended tail of spatial charge density distribution, larger charge radius and study of proton single particle states, Fermi energy and the wave functions indicate 2p halo like structure which supports direct 2p emission. The Coulomb and centrifugal barriers in experimentally identified 2p unbound 22Si show a quasi-bound state that ensures enough life time for such experimental probes. Our predictions are in good accord with experimental and other theoretical data available so far. Keywords: Relativistic mean-field theory, Nilson Strutinsky approach, Two-proton radioactivity, One- and two-proton separation energy, Halo nuclei, Proton drip-lines

  12. Recoiling supermassive black hole escape velocities from dark matter haloes

    Science.gov (United States)

    Choksi, Nick; Behroozi, Peter; Volonteri, Marta; Schneider, Raffaella; Ma, Chung-Pei; Silk, Joseph; Moster, Benjamin

    2017-12-01

    We simulate recoiling black hole trajectories from z = 20 to z = 0 in dark matter haloes, quantifying how parameter choices affect escape velocities. These choices include the strength of dynamical friction, the presence of stars and gas, the accelerating expansion of the Universe (Hubble acceleration), host halo accretion and motion, and seed black hole mass. Lambda cold dark matter halo accretion increases escape velocities by up to 0.6 dex and significantly shortens return time-scales compared to non-accreting cases. Other parameters change orbit damping rates but have subdominant effects on escape velocities; dynamical friction is weak at halo escape velocities, even for extreme parameter values. We present formulae for black hole escape velocities as a function of host halo mass and redshift. Finally, we discuss how these findings affect black hole mass assembly as well as minimum stellar and halo masses necessary to retain supermassive black holes.

  13. The “Building Blocks” of Stellar Halos

    Directory of Open Access Journals (Sweden)

    Kyle A. Oman

    2017-08-01

    Full Text Available The stellar halos of galaxies encode their accretion histories. In particular, the median metallicity of a halo is determined primarily by the mass of the most massive accreted object. We use hydrodynamical cosmological simulations from the apostle project to study the connection between the stellar mass, the metallicity distribution, and the stellar age distribution of a halo and the identity of its most massive progenitor. We find that the stellar populations in an accreted halo typically resemble the old stellar populations in a present-day dwarf galaxy with a stellar mass ∼0.2–0.5 dex greater than that of the stellar halo. This suggests that had they not been accreted, the primary progenitors of stellar halos would have evolved to resemble typical nearby dwarf irregulars.

  14. Isotope separation

    Science.gov (United States)

    Bartlett, Rodney J.; Morrey, John R.

    1978-01-01

    A method and apparatus is described for separating gas molecules containing one isotope of an element from gas molecules containing other isotopes of the same element in which all of the molecules of the gas are at the same electronic state in their ground state. Gas molecules in a gas stream containing one of the isotopes are selectively excited to a different electronic state while leaving the other gas molecules in their original ground state. Gas molecules containing one of the isotopes are then deflected from the other gas molecules in the stream and thus physically separated.

  15. Two-proton radioactivity with 2p halo in light mass nuclei A = 18-34

    Science.gov (United States)

    Saxena, G.; Kumawat, M.; Kaushik, M.; Jain, S. K.; Aggarwal, Mamta

    2017-12-01

    Two-proton radioactivity with 2p halo is reported theoretically in light mass nuclei A = 18- 34. We predict 19Mg, 22Si, 26S, 30Ar and 34Ca as promising candidates of ground state 2p-radioactivity with S2p 0. Observation of extended tail of spatial charge density distribution, larger charge radius and study of proton single particle states, Fermi energy and the wave functions indicate 2p halo like structure which supports direct 2p emission. The Coulomb and centrifugal barriers in experimentally identified 2p unbound 22Si show a quasi-bound state that ensures enough life time for such experimental probes. Our predictions are in good accord with experimental and other theoretical data available so far.

  16. N-body dark matter haloes with simple hierarchical histories

    Science.gov (United States)

    Jiang, Lilian; Helly, John C.; Cole, Shaun; Frenk, Carlos S.

    2014-05-01

    We present a new algorithm which groups the subhaloes found in cosmological N-body simulations by structure finders such as SUBFIND into dark matter haloes whose formation histories are strictly hierarchical. One advantage of these `Dhaloes' over the commonly used friends-of-friends (FoF) haloes is that they retain their individual identity in the cases when FoF haloes are artificially merged by tenuous bridges of particles or by an overlap of their outer diffuse haloes. Dhaloes are thus well suited for modelling galaxy formation and their merger trees form the basis of the Durham semi-analytic galaxy formation model, GALFORM. Applying the Dhalo construction to the Λ cold dark matter Millennium II Simulation, we find that approximately 90 per cent of Dhaloes have a one-to-one, bijective match with a corresponding FoF halo. The remaining 10 per cent are typically secondary components of large FoF haloes. Although the mass functions of both types of haloes are similar, the mass of Dhaloes correlates much more tightly with the virial mass, M200, than FoF haloes. Approximately 80 per cent of FoF and bijective and non-bijective Dhaloes are relaxed according to standard criteria. For these relaxed haloes, all three types have similar concentration-M200 relations and, at fixed mass, the concentration distributions are described accurately by log-normal distributions.

  17. Reversed Halo Sign: Presents in Different Pulmonary Diseases.

    Directory of Open Access Journals (Sweden)

    Xi Zhan

    Full Text Available To observe the incidence of reversed halo sign in different pulmonary diseases and the pathological correspondence of reversed halo sign.Retrospectively studied the high resolution computer tomography scans of all the patients who were admitted in our department with abnormal pulmonary imaging, from 1st of January 2011 to 31st of December 2013, and all the cases with reversed halo sign on the high resolution computer tomography were collected. Clinical data such as pathological findings and confirmed diagnosis of the patients with reversed halo sign on the high resolution computer tomography scan were collected and summarized.Of 1546 abnormal High resolution computer tomography scans 108 had a reverse halo sign present, including 108 cases were observed with reversed halo sign in the high resolution computer tomography, including 40 cases of pulmonary tuberculosis, 43 cases of cryptogenic organizing pneumonia, 16 cases of lung cancer, 7 cases of sarcoidosis, and 1 case of pulmonary cryptococcosis, 1 case of granulomatosis with polyangiitis. Reversed halo sign had a higher incidence in granulomatous diseases (16.28% compared with non-granulomatous diseases (9.97%.Reversed halo sign is relatively non specific; it can be observed in different lung diseases, and different phases of diseases; reversed halo sign is more commonly found in granulomatous diseases compared with non-granulomatous diseases, and is most commonly observed in pulmonary tuberculosis among the granulomatous diseases, and in cryptogenic organizing pneumonia among the non-granulomatous diseases.

  18. Brightest galaxies as halo centre tracers in SDSS DR7

    Science.gov (United States)

    Lange, Johannes U.; van den Bosch, Frank C.; Hearin, Andrew; Campbell, Duncan; Zentner, Andrew R.; Villarreal, Antonio; Mao, Yao-Yuan

    2018-01-01

    Determining the positions of halo centres in large-scale structure surveys is crucial for many cosmological studies. A common assumption is that halo centres correspond to the location of their brightest member galaxies. In this paper, we study the dynamics of brightest galaxies with respect to other halo members in the Sloan Digital Sky Survey DR7. Specifically, we look at the line-of-sight velocity and spatial offsets between brightest galaxies and their neighbours. We compare those to detailed mock catalogues, constructed from high-resolution, dark-matter-only N-body simulations, in which it is assumed that satellite galaxies trace dark matter subhaloes. This allows us to place constraints on the fraction fBNC of haloes in which the brightest galaxy is not the central. Compared to previous studies, we explicitly take into account the unrelaxed state of the host haloes, velocity offsets of halo cores and correlations between fBNC and the satellite occupation. We find that fBNC strongly decreases with the luminosity of the brightest galaxy and increases with the mass of the host halo. Overall, in the halo mass range 1013-1014.5 h- 1M⊙ we find fBNC ∼ 30 per cent, in good agreement with a previous study by Skibba et al. We discuss the implications of these findings for studies inferring the galaxy-halo connection from satellite kinematics, models of the conditional luminosity function and galaxy formation in general.

  19. Stable isotope compounds - production, detection, and application.

    Science.gov (United States)

    Zachleder, Vilém; Vítová, Milada; Hlavová, Monika; Moudříková, Šárka; Mojzeš, Peter; Heumann, Hermann; Becher, Johannes R; Bišová, Kateřina

    2018-01-19

    Stable isotopes are used in wide fields of application from natural tracers in biology, geology and archeology through studies of metabolic fluxes to their application as tracers in quantitative proteomics and structural biology. We review the use of stable isotopes of biogenic elements (H, C, N, O, S, Mg, Se) with the emphasis on hydrogen and its heavy isotope deuterium. We will discuss the limitations of enriching various compounds in stable isotopes when produced in living organisms. Finally, we overview methods for measuring stable isotopes, focusing on methods for detection in single cells in situ and their exploitation in modern biotechnologies. Copyright © 2018. Published by Elsevier Inc.

  20. Mapping stellar content to dark matter haloes - II. Halo mass is the main driver of galaxy quenching

    Science.gov (United States)

    Zu, Ying; Mandelbaum, Rachel

    2016-04-01

    We develop a simple yet comprehensive method to distinguish the underlying drivers of galaxy quenching, using the clustering and galaxy-galaxy lensing of red and blue galaxies in Sloan Digital Sky Survey. Building on the iHOD framework developed by Zu & Mandelbaum, we consider two quenching scenarios: (1) a `halo' quenching model in which halo mass is the sole driver for turning off star formation in both centrals and satellites; and (2) a `hybrid' quenching model in which the quenched fraction of galaxies depends on their stellar mass, while the satellite quenching has an extra dependence on halo mass. The two best-fitting models describe the red galaxy clustering and lensing equally well, but halo quenching provides significantly better fits to the blue galaxies above 1011 h-2 M⊙. The halo quenching model also correctly predicts the average halo mass of the red and blue centrals, showing excellent agreement with the direct weak lensing measurements of locally brightest galaxies. Models in which quenching is not tied to halo mass, including an age-matching model in which galaxy colour depends on halo age at fixed M*, fail to reproduce the observed halo mass for massive blue centrals. We find similar critical halo masses responsible for the quenching of centrals and satellites (˜1.5 × 1012 h-1 M⊙), hinting at a uniform quenching mechanism for both, e.g. the virial shock heating of infalling gas. The success of the iHOD halo quenching model provides strong evidence that the physical mechanism that quenches star formation in galaxies is tied principally to the masses of their dark matter haloes rather than the properties of their stellar components.

  1. Clustering dark energy and halo abundances

    Science.gov (United States)

    Batista, Ronaldo C.; Marra, Valerio

    2017-11-01

    Within the standard paradigm, dark energy is taken as a homogeneous fluid that drives the accelerated expansion of the universe and does not contribute to the mass of collapsed objects such as galaxies and galaxy clusters. The abundance of galaxy clusters—measured through a variety of channels—has been extensively used to constrain the normalization of the power spectrum: it is an important probe as it allows us to test if the standard ΛCDM model can indeed accurately describe the evolution of structures across billions of years. It is then quite significant that the Planck satellite has detected, via the Sunyaev-Zel'dovich effect, less clusters than expected according to the primary CMB anisotropies. One of the simplest generalizations that could reconcile these observations is to consider models in which dark energy is allowed to cluster, i.e., allowing its sound speed to vary. In this case, however, the standard methods to compute the abundance of galaxy clusters need to be adapted to account for the contributions of dark energy. In particular, we examine the case of clustering dark energy—a dark energy fluid with negligible sound speed—with a redshift-dependent equation of state. We carefully study how the halo mass function is modified in this scenario, highlighting corrections that have not been considered before in the literature. We address modifications in the growth function, collapse threshold, virialization densities and also changes in the comoving scale of collapse and mass function normalization. Our results show that clustering dark energy can impact halo abundances at the level of 10%-30%, depending on the halo mass, and that cluster counts are modified by about 30% at a redshift of unity.

  2. Fast low-energy halo-to-halo transfers between Sun–planet systems

    Directory of Open Access Journals (Sweden)

    Shang Haibin

    2014-04-01

    Full Text Available In this paper, the problem of fast low-energy halo-to-halo transfers between Sun–planet systems is discussed under ephemeris constraints. According to the structure of an invariant manifold, employing an invariant manifold and planetary gravity assist to save fuel consumption is analyzed from the view of orbital energy. Then, a pseudo-manifold is introduced to replace the invariant manifold in such a way that more transfer opportunities are allowed. Fast escape and capture can be achieved along the pseudo-manifold. Furthermore, a global searching method that is based on patched-models is proposed to find an appropriate transfer trajectory. In this searching method, the trajectory is divided into several segments that can be designed under simple dynamical models, and an analytical algorithm is developed for connecting the segments. Earth–Mars and Earth–Venus halo-to-halo transfers are designed to demonstrate the proposed approach. Numerical results show that the transfers that combine the pseudo-manifolds and planetary gravity assist can offer significant fuel consumption and flight time savings over traditional transfer schemes.

  3. Haloes, molecules and multi-neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Marques Moreno, F.M

    2003-01-01

    Away from the equilibrium between protons and neutrons within stable nuclei, many exotic nuclei exist. Most of the known nuclear properties evolve smoothly with exoticism, but some extreme proton-neutron combinations have revealed during the last decade completely new concepts. They will be illustrated through three examples: the extended and dilute halo formed by very weakly bound neutrons, the molecular-like neutron orbitals found in nuclei exhibiting a clustering, and the recently revived debate on the possible existence of neutral nuclei. The different experimental results will be reviewed, and we will see how several properties of these new phenomena can be well understood within relatively simple theoretical approaches. (author)

  4. Clustering and correlations in neutrons haloes

    Energy Technology Data Exchange (ETDEWEB)

    Orr, N.A

    2002-02-01

    In the present paper clustering and correlations within halo systems is explored. In particular, the application of neutron-neutron interferometry and Dalitz-plot type analyses is presented through the example provided by the dissociation of {sup 14}Be. A novel approach for producing and detection bound neutron clusters is also described. The observation of some 6 events with characteristics consistent with the liberation of a multi-neutron cluster in the breakup of {sup 14}Be - possibly in the channel {sup 10}Be+{sup 4}n - is discussed. (author)

  5. Project ECHO: Electronic Communications from Halo Orbit

    Science.gov (United States)

    Borrelli, Jason; Cooley, Bryan; Debole, Marcy; Hrivnak, Lance; Nielsen, Kenneth; Sangmeister, Gary; Wolfe, Matthew

    1994-01-01

    The design of a communications relay to provide constant access between the Earth and the far side of the Moon is presented. Placement of the relay in a halo orbit about the L2 Earth-Moon Lagrange point allows the satellite to maintain constant simultaneous communication between Earth and scientific payloads on the far side of the Moon. The requirements of NASA's Discovery-class missions adopted and modified for this design are: total project cost should not exceed $150 million excluding launch costs, launch must be provided by Delta-class vehicle, and the satellite should maintain an operational lifetime of 10 to 15 years. The spacecraft will follow a transfer trajectory to the L2 point, after launch by a Delta II 7925 vehicle in 1999. Low-level thrust is used for injection into a stationkeeping-free halo orbit once the spacecraft reaches the L2 point. The shape of this halo orbit is highly elliptical with the maximum excursion from the L2 point being 35000 km. A spun section and despun section connected through a bearing and power transfer assembly (BAPTA) compose the structure of the spacecraft. Communications equipment is placed on the despun section to provide for a stationary dual parabolic offset-feed array antenna system. The dual system is necessary to provide communications coverage during portions of maximum excursion on the halo orbit. Transmissions to the NASA Deep Space Network 34 m antenna include six channels (color video, two voice, scientific data from lunar payloads, satellite housekeeping and telemetry and uplinked commands) using the S- and X-bands. Four radioisotope thermoelectric generators (RTG's) provide a total of 1360 W to power onboard systems and any two of the four Hughes 13 cm ion thrusters at once. Output of the ion thrusters is approximately 17.8 mN each with xenon as the propellant. Presence of torques generated by solar pressure on the antenna dish require the addition of a 'skirt' extending from the spun section of the satellite

  6. Universal properties of dark matter halos.

    Science.gov (United States)

    Boyarsky, A; Neronov, A; Ruchayskiy, O; Tkachev, I

    2010-05-14

    We discuss the universal relation between density and size of observed dark matter halos that was recently shown to hold on a wide range of scales, from dwarf galaxies to galaxy clusters. Predictions of cold dark matter (ΛCDM) N-body simulations are consistent with this relation. We demonstrate that this property of ΛCDM can be understood analytically in the secondary infall model. Qualitative understanding given by this model provides a new way to predict which deviations from ΛCDM or large-scale modifications of gravity can affect universal behavior and, therefore, to constrain them observationally.

  7. Stellar Mass—Halo Mass Relation and Star Formation Efficiency in High-Mass Halos

    Science.gov (United States)

    Kravtsov, A. V.; Vikhlinin, A. A.; Meshcheryakov, A. V.

    2018-01-01

    We study relation between stellar mass and halo mass for high-mass halos using a sample of galaxy clusters with accurate measurements of stellar masses from optical and ifrared data and total masses from X-ray observations. We find that stellar mass of the brightest cluster galaxies (BCGs) scales as M *,BCG ∝ M 500 αBCG with the best fit slope of α BCG ≈ 0.4 ± 0.1. We measure scatter of M *,BCG at a fixed M 500 of ≈0.2 dex. We show that stellar mass-halo mass relations from abundance matching or halo modelling reported in recent studies underestimate masses of BCGs by a factor of ˜2-4. We argue that this is because these studies used stellar mass functions (SMF) based on photometry that severely underestimates the outer surface brightness profiles of massive galaxies. We show that M * -M relation derived using abundance matching with the recent SMF calibration by Bernardi et al. (2013) based on improved photometry is in a much better agreement with the relation we derive via direct calibration for observed clusters. The total stellar mass of galaxies correlates with total mass M 500 with the slope of ≈0.6 ± 0.1 and scatter of 0.1 dex. This indicates that efficiency with which baryons are converted into stars decreases with increasing cluster mass. The low scatter is due to large contribution of satellite galaxies: the stellar mass in satellite galaxies correlates with M 500 with scatter of ≈0.1 dex and best fit slope of αsat ≈ 0.8 ± 0.1. We show that for a fixed choice of the initial mass function (IMF) total stellar fraction in clusters is only a factor of 3-5 lower than the peak stellar fraction reached in M ≈ 1012 M ⊙ halos. The difference is only a factor of ˜1.5-3 if the IMF becomes progressively more bottom heavy with increasing mass in early type galaxies, as indicated by recent observational analyses. This means that the overall efficiency of star formation in massive halos is only moderately suppressed compared to L * galaxies and

  8. The Prevalence of the 22 deg Halo in Cirrus Clouds

    Science.gov (United States)

    Diedenhoven, vanBastiaan

    2014-01-01

    Halos at 22 deg from the sun attributed to randomly-orientated, pristine hexagonal crystals are frequently observed through ice clouds. These frequent sightings of halos formed by pristine crystals pose an apparent inconsistency with the dominance of distorted, nonpristine ice crystals indicated by in situ and remote sensing data. Furthermore, the 46 deg halo, which is associated with pristine hexagonal crystals as well, is observed far less frequently than the 22 deg halo. Considering that plausible mechanisms that could cause crystal distortion such as aggregation, sublimation, riming and collisions are stochastic processes that likely lead to distributions of crystals with varying distortion levels, here the presence of the 22 deg and 46 deg halo features in phase functions of mixtures of pristine and distorted hexagonal ice crystals is examined. We conclude that the 22 deg halo feature is generally present if the contribution by pristine crystals to the total scattering cross section is greater than only about 10% in the case of compact particles or columns, and greater than about 40% for plates. The 46 deg halo feature is present only if the mean distortion level is low and the contribution of pristine crystals to the total scattering cross section is above about 20%, 50% and 70%, in the case of compact crystals, plates and columns, respectively. These results indicate that frequent sightings of 22 deg halos are not inconsistent with the observed dominance of distorted, non-pristine ice crystals. Furthermore, the low mean distortion levels and large contributions by pristine crystals needed to produce the 461 halo features provide a potential explanation of the common sighting of the 22 deg halo without any detectable 46 deg halo.

  9. Diverse stellar haloes in nearby Milky Way mass disc galaxies

    Science.gov (United States)

    Harmsen, Benjamin; Monachesi, Antonela; Bell, Eric F.; de Jong, Roelof S.; Bailin, Jeremy; Radburn-Smith, David J.; Holwerda, Benne W.

    2017-04-01

    We have examined the resolved stellar populations at large galactocentric distances along the minor axis (from 10 kpc up to between 40 and 75 kpc), with limited major axis coverage, of six nearby highly inclined Milky Way (MW) mass disc galaxies using Hubble Space Telescope data from the Galaxy haloes, Outer discs, Substructure, Thick discs, and Star clusters (GHOSTS) survey. We select red giant branch stars to derive stellar halo density profiles. The projected minor axis density profiles can be approximated by power laws with projected slopes of -2 to -3.7 and a diversity of stellar halo masses of 1-6 × 109 M⊙, or 2-14 per cent of the total galaxy stellar masses. The typical intrinsic scatter around a smooth power-law fit is 0.05-0.1 dex owing to substructure. By comparing the minor and major axis profiles, we infer projected axis ratios c/a at ˜25 kpc between 0.4and0.75. The GHOSTS stellar haloes are diverse, lying between the extremes charted out by the (rather atypical) haloes of the MW and M31. We find a strong correlation between the stellar halo metallicities and the stellar halo masses. We compare our results with cosmological models, finding good agreement between our observations and accretion-only models where the stellar haloes are formed by the disruption of dwarf satellites. In particular, the strong observed correlation between stellar halo metallicity and mass is naturally reproduced. Low-resolution hydrodynamical models have unrealistically high stellar halo masses. Current high-resolution hydrodynamical models appear to predict stellar halo masses somewhat higher than observed but with reasonable metallicities, metallicity gradients, and density profiles.

  10. 77 FR 75672 - Manufacturer of Controlled Substances, Notice of Registration, Halo Pharmaceutical, Inc.

    Science.gov (United States)

    2012-12-21

    ... Enforcement Administration Manufacturer of Controlled Substances, Notice of Registration, Halo Pharmaceutical... 47114, Halo Pharmaceutical, Inc., 30 North Jefferson Road, Whippany, New Jersey 07981, made application... determined that the registration of Halo Pharmaceutical, Inc., to manufacture the listed basic classes of...

  11. 77 FR 16264 - Manufacturer of Controlled Substances, Notice of Registration; Halo Pharmaceutical Inc.

    Science.gov (United States)

    2012-03-20

    ... Enforcement Administration Manufacturer of Controlled Substances, Notice of Registration; Halo Pharmaceutical... FR 77850, Halo Pharmaceutical Inc., 30 North Jefferson Road, Whippany, New Jersey 07981, made... determined that the registration of Halo Pharmaceutical Inc. to manufacture the listed basic classes of...

  12. Convergence properties of halo merger trees; halo and substructure merger rates across cosmic history

    Science.gov (United States)

    Poole, Gregory B.; Mutch, Simon J.; Croton, Darren J.; Wyithe, Stuart

    2017-12-01

    We introduce GBPTREES: an algorithm for constructing merger trees from cosmological simulations, designed to identify and correct for pathological cases introduced by errors or ambiguities in the halo finding process. GBPTREES is built upon a halo matching method utilizing pseudo-radial moments constructed from radially sorted particle ID lists (no other information is required) and a scheme for classifying merger tree pathologies from networks of matches made to-and-from haloes across snapshots ranging forward-and-backward in time. Focusing on SUBFIND catalogues for this work, a sweep of parameters influencing our merger tree construction yields the optimal snapshot cadence and scanning range required for converged results. Pathologies proliferate when snapshots are spaced by ≲0.128 dynamical times; conveniently similar to that needed for convergence of semi-analytical modelling, as established by Benson et al. Total merger counts are converged at the level of ∼5 per cent for friends-of-friends (FoF) haloes of size np ≳ 75 across a factor of 512 in mass resolution, but substructure rates converge more slowly with mass resolution, reaching convergence of ∼10 per cent for np ≳ 100 and particle mass mp ≲ 109 M⊙. We present analytic fits to FoF and substructure merger rates across nearly all observed galactic history (z ≤ 8.5). While we find good agreement with the results presented by Fakhouri et al. for FoF haloes, a slightly flatter dependence on merger ratio and increased major merger rates are found, reducing previously reported discrepancies with extended Press-Schechter estimates. When appropriately defined, substructure merger rates show a similar mass ratio dependence as FoF rates, but with stronger mass and redshift dependencies for their normalization.

  13. Rb-Sr, Sm-Nd and Lu-Hf isotope systematics of the lunar Mg-suite: the age of the lunar crust and its relation to the time of Moon formation

    National Research Council Canada - National Science Library

    Carlson, Richard W; Borg, Lars E; Gaffney, Amy M; Boyet, Maud

    2014-01-01

    ... of lunar crust formation and the history of the source materials of the Mg-suite. Isochron ages determined in this study for 77215 are: Rb-Sr=4450±270 Ma, (147)Sm-(143)Nd=4283±23 Ma and Lu-Hf=4421±68 Ma...

  14. Alternative techniques for beam halo measurements

    CERN Document Server

    Welsch, CP; Burel, B; Lefèvre, T; Chapman, T; Pilon, MJ

    2006-01-01

    In future high intensity, high energy accelerators it must be ensured that particle losses are minimized, as activation of the vacuum chambers or other components makes maintenance and upgrade work time consuming and costly. It is imperative to have a clear understanding of the mechanisms that can lead to halo formation and to have the possibility to test available theoretical models with an adequate experimental setup. Measurements based on optical transition radiation (OTR) are a well-established technique for measurements of the transverse beam profile. However, in order to be suitable for halo measurements as well, the dynamic range of the final image acquisition system needs to be high, being able to cover at least five orders of magnitude in intensity changes. Here, the performance of a standard acquisition system as it is used in the CLIC test facility (CTF3) is compared to a step-by-step measurement with a small movable photo multiplier tube and an innovative camera system based on charge injection de...

  15. The CMS Beam Halo Monitor Detector System

    CERN Document Server

    CMS Collaboration

    2015-01-01

    A new Beam Halo Monitor (BHM) detector system has been installed in the CMS cavern to measure the machine-induced background (MIB) from the LHC. This background originates from interactions of the LHC beam halo with the final set of collimators before the CMS experiment and from beam gas interactions. The BHM detector uses the directional nature of Cherenkov radiation and event timing to select particles coming from the direction of the beam and to suppress those originating from the interaction point. It consists of 40 quartz rods, placed on each side of the CMS detector, coupled to UV sensitive PMTs. For each bunch crossing the PMT signal is digitized by a charge integrating ASIC and the arrival time of the signal is recorded. The data are processed in real time to yield a precise measurement of per-bunch-crossing background rate. This measurement is made available to CMS and the LHC, to provide real-time feedback on the beam quality and to improve the efficiency of data taking. In this talk we will describ...

  16. The CMS Beam Halo Monitor Detector System

    CERN Document Server

    Stifter, Kelly

    2015-01-01

    A new Beam Halo Monitor (BHM) detector system has been installed in the CMS cavern to measure the machine-induced background (MIB) from the LHC. This background originates from interactions of the LHC beam halo with the final set of collimators before the CMS experiment and from beam gas interactions. The BHM detector uses the directional nature of Cherenkov radiation and event timing to select particles coming from the direction of the beam and to supress those originating from the interaction point. It consists of 40 quartz rods, placed on each side of the CMS detector, coupled to UV sensitive PMTs. For each bunch crossing the PMT signal is digitized by a charge integrating ASIC and the arrival time of the signal is recorded. The data are processed in real time to yield a precise measurement of per-bunch-crossing background rate. This measurement is made available to CMS and the LHC, to provide real-time feedback on the beam quality and to improve the efficiency of data taking. In this talk we will descri...

  17. A 500 PARSEC HALO SURROUNDING THE GALACTIC GLOBULAR NGC 1851

    NARCIS (Netherlands)

    Olszewski, Edward W.; Saha, Abhijit; Knezek, Patricia; Subramaniam, Annapurni; de Boer, Thomas; Seitzer, Patrick

    2009-01-01

    Using imaging that shows 4 mag of main-sequence stars, we have discovered that the Galactic globular cluster NGC 1851 is surrounded by a halo that is visible from the tidal radius of 700 arcsec (41 pc) to more than 4500 arcsec (> 250 pc). This halo is symmetric and falls in density as a power law of

  18. Is the dark halo of our Galaxy spherical?

    NARCIS (Netherlands)

    Helmi, A

    2004-01-01

    It has been recently claimed that the confined structure of the debris from the Sagittarius dwarf implies that the dark matter halo of our Galaxy should be nearly spherical, in strong contrast with predictions from cold dark matter simulations, where dark haloes are found to have typical density

  19. Investigating Halo and Ceiling Effects in Student Evaluations of Instruction

    Science.gov (United States)

    Keeley, Jared W.; English, Taylor; Irons, Jessica; Henslee, Amber M.

    2013-01-01

    Many measurement biases affect student evaluations of instruction (SEIs). However, two have been relatively understudied: halo effects and ceiling/floor effects. This study examined these effects in two ways. To examine the halo effect, using a videotaped lecture, we manipulated specific teacher behaviors to be "good" or "bad"…

  20. Binary white dwarfs in the halo of the Milky Way

    NARCIS (Netherlands)

    van Oirschot, Pim; Nelemans, Gijs; Toonen, Silvia; Pols, Onno; Brown, Anthony G. A.; Helmi, Amina; Portegies Zwart, Simon

    Aims: We study single and binary white dwarfs in the inner halo of the Milky Way in order to learn more about the conditions under which the population of halo stars was born, such as the initial mass function (IMF), the star formation history, or the binary fraction. Methods: We simulate the

  1. Disk response to a lopsided halo potential (Jog 1997, 2002):

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. Disk response to a lopsided halo potential (Jog 1997, 2002):. consider small (few %) perturbation in potential. --- solve equations of motion using epicyclic theory. The symmetric disk potential = ψ_0 (R ) = Vc 2 ln R. and the perturbation halo potential = Vc 2 εlop cos φ ...

  2. THE COSMOGRID SIMULATION: STATISTICAL PROPERTIES OF SMALL DARK MATTER HALOS

    Energy Technology Data Exchange (ETDEWEB)

    Ishiyama, Tomoaki [Center for Computational Science, University of Tsukuba, 1-1-1, Tennodai, Tsukuba, Ibaraki 305-8577 (Japan); Rieder, Steven; Portegies Zwart, Simon [Sterrewacht Leiden, Leiden University, P.O. Box 9513, 2300-RA Leiden (Netherlands); Makino, Junichiro [Graduate School of Science and Engineering, Tokyo Institute of Technology (Japan); Groen, Derek [Centre for Computational Science, Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ (United Kingdom); Nitadori, Keigo [RIKEN Advanced Institute for Computational Science (Japan); De Laat, Cees [Section System and Network Engineering, University of Amsterdam, Amsterdam (Netherlands); McMillan, Stephen [Department of Physics, Drexel University, Philadelphia, PA 19104 (United States); Hiraki, Kei [Department of Creative Informatics, Graduate School of Information Science and Technology, the University of Tokyo (Japan); Harfst, Stefan, E-mail: ishiyama@ccs.tsukuba.ac.jp [Center for Astronomy and Astrophysics, Technical University Berlin, Hardenbergstr. 36, D-10623 Berlin (Germany)

    2013-04-20

    We present the results of the ''Cosmogrid'' cosmological N-body simulation suites based on the concordance LCDM model. The Cosmogrid simulation was performed in a 30 Mpc box with 2048{sup 3} particles. The mass of each particle is 1.28 Multiplication-Sign 10{sup 5} M{sub Sun }, which is sufficient to resolve ultra-faint dwarfs. We found that the halo mass function shows good agreement with the Sheth and Tormen fitting function down to {approx}10{sup 7} M{sub Sun }. We have analyzed the spherically averaged density profiles of the three most massive halos which are of galaxy group size and contain at least 170 million particles. The slopes of these density profiles become shallower than -1 at the innermost radius. We also find a clear correlation of halo concentration with mass. The mass dependence of the concentration parameter cannot be expressed by a single power law, however a simple model based on the Press-Schechter theory proposed by Navarro et al. gives reasonable agreement with this dependence. The spin parameter does not show a correlation with the halo mass. The probability distribution functions for both concentration and spin are well fitted by the log-normal distribution for halos with the masses larger than {approx}10{sup 8} M{sub Sun }. The subhalo abundance depends on the halo mass. Galaxy-sized halos have 50% more subhalos than {approx}10{sup 11} M{sub Sun} halos have.

  3. The Cosmogrid Simulation: Statistical Properties of Small Dark Matter Halos

    Science.gov (United States)

    Ishiyama, Tomoaki; Rieder, Steven; Makino, Junichiro; Portegies Zwart, Simon; Groen, Derek; Nitadori, Keigo; de Laat, Cees; McMillan, Stephen; Hiraki, Kei; Harfst, Stefan

    2013-04-01

    We present the results of the "Cosmogrid" cosmological N-body simulation suites based on the concordance LCDM model. The Cosmogrid simulation was performed in a 30 Mpc box with 20483 particles. The mass of each particle is 1.28 × 105 M ⊙, which is sufficient to resolve ultra-faint dwarfs. We found that the halo mass function shows good agreement with the Sheth & Tormen fitting function down to ~107 M ⊙. We have analyzed the spherically averaged density profiles of the three most massive halos which are of galaxy group size and contain at least 170 million particles. The slopes of these density profiles become shallower than -1 at the innermost radius. We also find a clear correlation of halo concentration with mass. The mass dependence of the concentration parameter cannot be expressed by a single power law, however a simple model based on the Press-Schechter theory proposed by Navarro et al. gives reasonable agreement with this dependence. The spin parameter does not show a correlation with the halo mass. The probability distribution functions for both concentration and spin are well fitted by the log-normal distribution for halos with the masses larger than ~108 M ⊙. The subhalo abundance depends on the halo mass. Galaxy-sized halos have 50% more subhalos than ~1011 M ⊙ halos have.

  4. A two-point correlation function for Galactic halo stars

    NARCIS (Netherlands)

    Cooper, A. P.; Cole, S.; Frenk, C. S.; Helmi, A.

    2011-01-01

    We describe a correlation function statistic that quantifies the amount of spatial and kinematic substructure in the stellar halo. We test this statistic using model stellar halo realizations constructed from the Aquarius suite of six high-resolution cosmological N-body simulations, in combination

  5. Influence of halo doping profiles on MOS transistor mismatch

    NARCIS (Netherlands)

    Andricciola, P.; Tuinhout, H.

    2009-01-01

    Halo implants are used in modern CMOS technology to reduce the short channel effect. However, the lateral non-uniformity of the channel doping has been proven to degenerate the mismatch performance. With this paper we want to discuss the influence of the halo profile on MOS transistor mismatch. The

  6. A Hidden Radio Halo in the Galaxy Cluster A1682?

    Indian Academy of Sciences (India)

    High sensitivity observations of radio halos in galaxy clusters at frequencies ≤ 330 MHz are still relatively rare, and very little is known compared to the classical 1.4 GHz images. The few radio halos imaged down to 150–240 MHz show a considerable spread in size, morphology and spectral properties. All clusters ...

  7. Double folding model analysis of elastic scattering of halo nucleus ...

    Indian Academy of Sciences (India)

    features of halo nuclei largely affect the interaction with light and heavy targets at low bombarding energies and have created tremendous interest in the study of nuclear reac- tions. Elastic scattering is sensitive to the nature of the surface of nuclei and hence it is effective in studying halo nuclei. Pramana – J. Phys., Vol.

  8. The Connection between Radio Halos and Cluster Mergers and the ...

    Indian Academy of Sciences (India)

    We discuss the statistical properties of the radio halo population in galaxy clusters. Radio bi-modality is observed in galaxy clusters: a fraction of clusters host giant radio halos while a majority of clusters do not show evidence of diffuse cluster-scale radio emission. The radio bi-modality has a correspondence in terms of ...

  9. RR Lyrae to build up the Galactic Halo

    Science.gov (United States)

    Fiorentino, Giuliana

    2015-08-01

    We compare the period and period-amplitude distributions for a sizeable sample of rrab in dwarfs (~1300stars) with those in the galactic halo (~14,000stars) and globular clusters (~1000stars). Field rrab show a significant change in their period distribution when moving from the inner (dg~14kpc) halo regions, suggesting that the halo formed from (at least) two dissimilar progenitors or events. Rrab in dwarfs-as observed today-do not appear to follow the pulsation properties shown by those in the galactic halo, nor do they have the same properties as rrls in globulars. Only massive and metal rich satellites likely have mainly contributed to the galactic halo formation, e.g. Sgr dSph.

  10. Electronic structure of MgB2

    Indian Academy of Sciences (India)

    Boron isotope effect [2] has been observed in MgB2 re- vealing that the pairing mechanism ... energy there is a flat band which is predominantly of boron 2p origin. This band makes a large contribution to the ... This yields a Tc = 24.7 K. We thus find that a phonon mediated theory of strong coupling superconductivity gives a ...

  11. Binary white dwarfs in the halo of the Milky Way

    Science.gov (United States)

    van Oirschot, Pim; Nelemans, Gijs; Toonen, Silvia; Pols, Onno; Brown, Anthony G. A.; Helmi, Amina; Portegies Zwart, Simon

    2014-09-01

    Aims: We study single and binary white dwarfs in the inner halo of the Milky Way in order to learn more about the conditions under which the population of halo stars was born, such as the initial mass function (IMF), the star formation history, or the binary fraction. Methods: We simulate the evolution of low-metallicity halo stars at distances up to ~3 kpc using the binary population synthesis code SeBa. We use two different white dwarf cooling models to predict the present-day luminosities of halo white dwarfs. We determine the white dwarf luminosity functions (WDLFs) for eight different halo models and compare these with the observed halo WDLF of white dwarfs in the SuperCOSMOS Sky Survey. Furthermore, we predict the properties of binary white dwarfs in the halo and determine the number of halo white dwarfs that is expected to be observed with the Gaia satellite. Results: By comparing the WDLFs, we find that a standard IMF matches the observations more accurately than a top-heavy one, but the difference with a bottom-heavy IMF is small. A burst of star formation 13 Gyr ago fits slightly better than a star formation burst 10 Gyr ago and also slightly better than continuous star formation 10-13 Gyr ago. Gaia will be the first instument to constrain the bright end of the field halo WDLF, where contributions from binary WDs are considerable. Many of these will have He cores, of which a handful have atypical surface gravities (log g 0 in our standard model for WD cooling. These so called pre-WDs, if observed, can help us to constrain white dwarf cooling models and might teach us something about the fraction of halo stars that reside in binaries. Appendices are available in electronic form at http://www.aanda.org

  12. What sets the central structure of dark matter haloes?

    Science.gov (United States)

    Ogiya, Go; Hahn, Oliver

    2018-02-01

    Dark matter (DM) haloes forming near the thermal cut-off scale of the density perturbations are unique, since they are the smallest objects and form through monolithic gravitational collapse, while larger haloes contrastingly have experienced mergers. While standard cold dark matter (CDM) simulations readily produce haloes that follow the universal Navarro-Frenk-White (NFW) density profile with an inner slope, ρ ∝ r-α, with α = 1, recent simulations have found that when the free-streaming cut-off expected for the CDM model is resolved, the resulting haloes follow nearly power-law density profiles of α ∼ 1.5. In this paper, we study the formation of density cusps in haloes using idealized N-body simulations of the collapse of proto-haloes. When the proto-halo profile is initially cored due to particle free-streaming at high redshift, we universally find ∼r-1.5 profiles irrespective of the proto-halo profile slope outside the core and large-scale non-spherical perturbations. Quite in contrast, when the proto-halo has a power-law profile, then we obtain profiles compatible with the NFW shape when the density slope of the proto-halo patch is shallower than a critical value, αini ∼ 0.3, while the final slope can be steeper for αini ≳ 0.3. We further demonstrate that the r-1.5 profiles are sensitive to small-scale noise, which gradually drives them towards an inner slope of -1, where they become resilient to such perturbations. We demonstrate that the r-1.5 solutions are in hydrostatic equilibrium, largely consistent with a simple analytic model, and provide arguments that angular momentum appears to determine the inner slope.

  13. Coulomb excitation of (31)Mg

    CERN Document Server

    Seidlitz, M; Reiter, P; Bildstein, V; Blazhev, A; Bree, N; Bruyneel, B; Cederkall, J; Clement, E; Davinson, T; van Duppen, P; Ekstrom, A; Finke, F; Fraile, L M; Geibel, K; Gernhauser, R; Hess, H; Holler, A; Huyse, M; Ivanov, O; Jolie, J; Kalkuhler, M; Kotthaus, T; Krucken, R; Lutter, R; Piselli, E; Scheit, H; Stefanescu, I; van de Walle, J; Voulot, D; Warr, N; Wenander, F; Wiens, A

    2011-01-01

    The ground state properties of ^3^1Mg indicate a change of nuclear shape at N=19 with a deformed J^@p=1/2^+ intruder state as a ground state, implying that ^3^1Mg is part of the ''island of inversion''. The collective properties of excited states were the subject of a Coulomb excitation experiment at REX-ISOLDE, CERN, employing a radioactive ^3^1Mg beam. De-excitation @c-rays were detected by the MINIBALL @c-spectrometer in coincidence with scattered particles in a segmented Si-detector. The level scheme of ^3^1Mg was extended. Spin and parity assignment of the 945 keV state yielded 5/2^+ and its de-excitation is dominated by a strong collective M1 transition. Comparison of the transition probabilities of ^3^0^,^3^1^,^3^2Mg establishes that for th e N=19 magnesium isotope not only the ground state but also excited states are largely dominated by a deformed pf intruder configuration.

  14. Leatherback Isotopes

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — SWFSC is currently working on a project identifying global marine isotopes using leatherback turtles (Dermochelys coriacea) as the indicator species. We currently...

  15. Isotope Identification

    Energy Technology Data Exchange (ETDEWEB)

    Karpius, Peter Joseph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-09-18

    The objective of this training modules is to examine the process of using gamma spectroscopy for radionuclide identification; apply pattern recognition to gamma spectra; identify methods of verifying energy calibration; and discuss potential causes of isotope misidentification.

  16. [Halos and multifocal intraocular lenses: origin and interpretation].

    Science.gov (United States)

    Alba-Bueno, F; Vega, F; Millán, M S

    2014-10-01

    To present the theoretical and experimental characterization of the halo in multifocal intraocular lenses (MIOL). The origin of the halo in a MIOL is the overlaying of 2 or more images. Using geometrical optics, it can be demonstrated that the diameter of each halo depends on the addition of the lens (ΔP), the base power (P(d)), and the diameter of the IOL that contributes to the «non-focused» focus. In the image plane that corresponds to the distance focus, the halo diameter (δH(d)) is given by: δH(d)=d(pn) ΔP/P(d), where d(pn) is the diameter of the IOL that contributes to the near focus. Analogously, in the near image plane the halo diameter (δH(n)) is: δH(n)=d(pd) ΔP/P(d), where d(pd) is the diameter of the IOL that contributes to the distance focus. Patients perceive halos when they see bright objects over a relatively dark background. In vitro, the halo can be characterized by analyzing the intensity profile of the image of a pinhole that is focused by each of the foci of a MIOL. A comparison has been made between the halos induced by different MIOL of the same base power (20D) in an optical bench. As predicted by theory, the larger the addition of the MIOL, the larger the halo diameter. For large pupils and with MIOL with similar aspheric designs and addition (SN6AD3 vs ZMA00), the apodized MIOL has a smaller halo diameter than a non-apodized one in distance vision, while in near vision the size is very similar, but the relative intensity is higher in the apodized MIOL. When comparing lenses with the same diffractive design, but with different spherical-aspheric base design (SN60D3 vs SN6AD3), the halo in distance vision of the spherical MIOL is larger, while in near vision the spherical IOL induces a smaller halo, but with higher intensity due to the spherical aberration of the distance focus in the near image. In the case of a trifocal-diffractive IOL (AT LISA 839MP) the most noticeable characteristic is the double-halo formation due to the 2 non

  17. Magnesium isotope systematics in Martian meteorites

    Science.gov (United States)

    Magna, Tomáš; Hu, Yan; Teng, Fang-Zhen; Mezger, Klaus

    2017-09-01

    Magnesium isotope compositions are reported for a suite of Martian meteorites that span the range of petrological and geochemical types recognized to date for Mars, including crustal breccia Northwest Africa (NWA) 7034. The δ26Mg values (per mil units relative to DSM-3 reference material) range from -0.32 to -0.11‰; basaltic shergottites and nakhlites lie to the heavier end of the Mg isotope range whereas olivine-phyric, olivine-orthopyroxene-phyric and lherzolitic shergottites, and chassignites have slightly lighter Mg isotope compositions, attesting to modest correlation of Mg isotopes and petrology of the samples. Slightly heavier Mg isotope compositions found for surface-related materials (NWA 7034, black glass fraction of the Tissint shergottite fall; δ26Mg > -0.17‰) indicate measurable Mg isotope difference between the Martian mantle and crust but the true extent of Mg isotope fractionation for Martian surface materials remains unconstrained. The range of δ26Mg values from -0.19 to -0.11‰ in nakhlites is most likely due to accumulation of clinopyroxene during petrogenesis rather than garnet fractionation in the source or assimilation of surface material modified at low temperatures. The rather restricted range in Mg isotope compositions between spatially and temporally distinct mantle-derived samples supports the idea of inefficient/absent major tectonic cycles on Mars, which would include plate tectonics and large-scale recycling of isotopically fractionated surface materials back into the Martian mantle. The cumulative δ26Mg value of Martian samples, which are not influenced by late-stage alteration processes and/or crust-mantle interactions, is - 0.271 ± 0.040 ‰ (2SD) and is considered to reflect δ26Mg value of the Bulk Silicate Mars. This value is robust taking into account the range of lithologies involved in this estimate. It also attests to the lack of the Mg isotope variability reported for the inner Solar System bodies at current

  18. Historic halo displays as weather indicator: Criteria and examples

    Science.gov (United States)

    Neuhäuser, Dagmar L.; Neuhäuser, Ralph

    2016-04-01

    There are numerous celestial signs reported in historic records, many of them refer to atmospheric ("sub-lunar") phenomena, such as ice halos and aurorae. In an interdisciplinary collaboration between astrophysics and cultural astronomy, we noticed that celestial observations including meteorological phenomena are often misinterpreted, mostly due to missing genuine criteria: especially ice crystal halos were recorded frequently in past centuries for religious reasons, but are mistaken nowadays often for other phenomena like aurorae. Ice halo displays yield clear information on humidity and temperature in certain atmospheric layers, and thereby indicate certain weather patterns. Ancient so-called rain makers used halo observations for weather forecast; e.g., a connection between certain halo displays and rain a few day later is statistically significant. Ice halos exist around sun and moon and are reported for both (they can stay for several days): many near, middle, and far eastern records from day- and night-time include such observations with high frequency. (Partly based on publications on halos by D.L. Neuhäuser & R. Neuhäuser, available at http://www.astro.uni-jena.de/index.php/terra-astronomy.html)

  19. Accurate mass and velocity functions of dark matter haloes

    Science.gov (United States)

    Comparat, Johan; Prada, Francisco; Yepes, Gustavo; Klypin, Anatoly

    2017-08-01

    N-body cosmological simulations are an essential tool to understand the observed distribution of galaxies. We use the MultiDark simulation suite, run with the Planck cosmological parameters, to revisit the mass and velocity functions. At redshift z = 0, the simulations cover four orders of magnitude in halo mass from ˜1011M⊙ with 8783 874 distinct haloes and 532 533 subhaloes. The total volume used is ˜515 Gpc3, more than eight times larger than in previous studies. We measure and model the halo mass function, its covariance matrix w.r.t halo mass and the large-scale halo bias. With the formalism of the excursion-set mass function, we explicit the tight interconnection between the covariance matrix, bias and halo mass function. We obtain a very accurate (Planck cosmology. Finally, we provide precise analytical fits of the Vmax maximum velocity function up to redshift z < 2.3 to push for the development of halo occupation distribution using Vmax. The data and the analysis code are made publicly available in the Skies and Universes data base.

  20. Towards laser spectroscopy of the proton-halo candidate boron-8

    Science.gov (United States)

    Maaß, Bernhard; Müller, Peter; Nörtershäuser, Wilfried; Clark, Jason; Gorges, Christian; Kaufmann, Simon; König, Kristian; Krämer, Jörg; Levand, Anthony; Orford, Rodney; Sánchez, Rodolfo; Savard, Guy; Sommer, Felix

    2017-11-01

    We propose to determine the nuclear charge radius of 8B by high-resolution laser spectroscopy. 8B (t 1/2 = 770 ms) is perhaps the best candidate of a nucleus exhibiting an extended proton wave-function or "one-proton-halo" in a more descriptive picture. Laser spectroscopic measurements of the isotope shift will be used to probe the change in nuclear charge radius along the three boron isotopes 8B, 10B and 11B. The change in nuclear charge radius directly correlates with the extent of the proton wave function. In-flight production and preparation of sufficient yields of 8B ions at low energies is provided by the Argonne Tandem Linac Accelerator System (ATLAS) at Argonne National Laboratory (ANL) in Chicago, IL, USA. Subsequently, the ions will be guided through a charge exchange cell for neutralization and the fluorescence signal of the atoms which interact with the resonant laser light will be detected. The charge radius can then be extracted from the measured isotope shift by employing highly accurate atomic theory calculations of this five-electron system which are carried out presently.

  1. Chemical Cartography. I. A Carbonicity Map of the Galactic Halo

    Science.gov (United States)

    Lee, Young Sun; Beers, Timothy C.; Kim, Young Kwang; Placco, Vinicius; Yoon, Jinmi; Carollo, Daniela; Masseron, Thomas; Jung, Jaehun

    2017-02-01

    We present the first map of carbonicity, [C/Fe], for the halo system of the Milky Way, based on a sample of over 100,000 main-sequence turnoff stars with available spectroscopy from the Sloan Digital Sky Survey. This map, which explores distances up to 15 kpc from the Sun, reveals clear evidence for the dual nature of the Galactic halo, based on the spatial distribution of stellar carbonicity. The metallicity distribution functions of stars in the inner- and outer-halo regions of the carbonicity map reproduce those previously argued to arise from contributions of the inner- and outer-halo populations, with peaks at [Fe/H] = -1.5 and -2.2, respectively. From consideration of the absolute carbon abundances for our sample, A(C), we also confirm that the carbon-enhanced metal-poor (CEMP) stars in the outer-halo region exhibit a higher frequency of CEMP-no stars (those with no overabundances of heavy neutron-capture elements) than of CEMP-s stars (those with strong overabundances of elements associated with the s-process), whereas the stars in the inner-halo region exhibit a higher frequency of CEMP-s stars. We argue that the contrast in the behavior of the CEMP-no and CEMP-s fractions in these regions arises from differences in the mass distributions of the mini-halos from which the stars of the inner- and outer-halo populations formed, which gives rise in turn to the observed dichotomy of the Galactic halo.

  2. Chemical Cartography. I. A Carbonicity Map of the Galactic Halo

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Young Sun; Kim, Young Kwang [Department of Astronomy and Space Science, Chungnam National University, Daejeon 34134 (Korea, Republic of); Beers, Timothy C.; Placco, Vinicius; Yoon, Jinmi [Department of Physics and JINA Center for the Evolution of the Elements, University of Notre Dame, Notre Dame, IN 46556 (United States); Carollo, Daniela [Research School of Astronomy and Astrophysics, The Australian National University, Canberra, ACT 2611 (Australia); Masseron, Thomas [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Jung, Jaehun, E-mail: youngsun@cnu.ac.kr [Department of Astronomy, Space Science, and Geology, Chungnam National University, Daejeon 34134 (Korea, Republic of)

    2017-02-10

    We present the first map of carbonicity, [C/Fe], for the halo system of the Milky Way, based on a sample of over 100,000 main-sequence turnoff stars with available spectroscopy from the Sloan Digital Sky Survey. This map, which explores distances up to 15 kpc from the Sun, reveals clear evidence for the dual nature of the Galactic halo, based on the spatial distribution of stellar carbonicity. The metallicity distribution functions of stars in the inner- and outer-halo regions of the carbonicity map reproduce those previously argued to arise from contributions of the inner- and outer-halo populations, with peaks at [Fe/H] = −1.5 and −2.2, respectively. From consideration of the absolute carbon abundances for our sample, A (C), we also confirm that the carbon-enhanced metal-poor (CEMP) stars in the outer-halo region exhibit a higher frequency of CEMP-no stars (those with no overabundances of heavy neutron-capture elements) than of CEMP- s stars (those with strong overabundances of elements associated with the s -process), whereas the stars in the inner-halo region exhibit a higher frequency of CEMP- s stars. We argue that the contrast in the behavior of the CEMP-no and CEMP- s fractions in these regions arises from differences in the mass distributions of the mini-halos from which the stars of the inner- and outer-halo populations formed, which gives rise in turn to the observed dichotomy of the Galactic halo.

  3. Stellar halos: a rosetta stone for galaxy formation and cosmology

    Science.gov (United States)

    Inglis Read, Justin

    2015-08-01

    Stellar halos make up about a percent of the total stellar mass in galaxies. Yet their old age and long phase mixing times make them living fossil records of galactic history. In this talk, I review the latest simulations of structure formation in our standard Lambda Cold Dark Matter cosmology. I discuss the latest predictions for stellar halos and the relationship between the stellar halo light and the underlying dark matter. Finally, I discuss how these simulations compare to observations of the Milky Way and Andromeda and, ultimately, what this means for our cosmological model and the formation history of the Galaxy.

  4. Peripheral cholangiocarcinoma : Radiologic significance of hypoechoic halo sign on sonography

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Young Eok; Moon, Haeng Jin; Lee, Eun Ja; Ahn, In Oak [Gyeong Sang National Univ., College of Medicine, Chinju (Korea, Republic of)

    2001-12-01

    To determine the prevalence and characteristics of the hypoechoic halo sign in peripheral cholangiocarcinoma. Seventeen sonograms of 17 patients with peripheral cholangiocarcinoma histologically proven by either percutaneous needle biopsy (n=16) or surgical biopsy (n=1) were retrospectively reviewed. The size, margin, homogeneity and internal echogenicity of the masses as well as their peritumoral ductal dilatation and intratumoral calcification were ascertained, and the presence of a hypoechoic halo, and if present, its thickness and type, were also determined. We arbitrarily defined a 'thin' and 'thick' halo respectively, as one with a thickness less than of less than 3 mm, and 3 mm or more, and classified halos as 'intratumoral', 'extratumoral', or 'mixed'. Tumor diameter ranged from 4 to 13.5 (mean,7.3)cm, and the margin was well-defined in 15 cases (smooth: n=2; lobulated: n=13) and irregular in two. Echogenicity was slightly heterogeneous in 11 cases, severely heterogeneous in three, and hemogeneous in three, while the central portion was hyperechoic in eight cases, isoechoic in seven, and hypoechoic in only two. A hypoechoic halo was detected in 10 of 15 tumors (67%) with isoechoic centers. In evaluating the halo, two cases in which the mass was hypoechoic were excluded. All ten hypoechoic halos were at least 3 (range, 4-13; mean, 8.3) mm thick; in two cases the presence of a halo was equivocal, and in three there was no halo. Eight of ten halos were the mixed type, two were intratumoral, and none were extratumoral. Peritumoral ductal dilatation was seen in four cases (24%), but no internal calcification was observed. US showed that the margins of peripheral cholangiocarcinomas were mostly well-defined and smooth (12%) or lobulated (76%), and that masses were mainly heterogeneous (64%) A hypoechoic halo, which in all cases was thick and in 80% of cases was mixed, was noted in 67% of tumors with a hyper (47

  5. Evolution of Southern Hemisphere spring air masses observed by HALOE

    Science.gov (United States)

    Pierce, R. Bradley; Grose, William L.; Russell, James M., III; Tuck, Adrian F.

    1994-01-01

    The evolution of Southern Hemisphere air masses observed by the Halogen Occultation Experiment (HALOE) during September 21 through October 15, 1992, is investigated using isentropic trajectories computed from United Kingdom Meteorological Office (UKMO) assimilated winds and temperatures. Maps of constituent concentrations are obtained by accumulation of air masses from previous HALOE occultations. Lagged correlations between initial and subsequent HALOE observations of the same air mass are used to validate the air mass trajectories. High correlations are found for lag times as large as 10 days. Frequency distributions of the air mass constituent concentrations are used to examine constituent distributions in and around the Southern Hemisphere polar vortex.

  6. Connecting Galaxies, Halos, and Star Formation Rates Across Cosmic Time

    Energy Technology Data Exchange (ETDEWEB)

    Conroy, Charlie; Wechsler, Risa H.

    2008-06-02

    A simple, observationally-motivated model is presented for understanding how halo masses, galaxy stellar masses, and star formation rates are related, and how these relations evolve with time. The relation between halo mass and galaxy stellar mass is determined by matching the observed spatial abundance of galaxies to the expected spatial abundance of halos at multiple epochs--i.e. more massive galaxies are assigned to more massive halos at each epoch. This 'abundance matching' technique has been shown previously to reproduce the observed luminosity- and scale-dependence of galaxy clustering over a range of epochs. Halos at different epochs are connected by halo mass accretion histories estimated from N-body simulations. The halo-galaxy connection at fixed epochs in conjunction with the connection between halos across time provides a connection between observed galaxies across time. With approximations for the impact of merging and accretion on the growth of galaxies, one can then directly infer the star formation histories of galaxies as a function of stellar and halo mass. This model is tuned to match both the observed evolution of the stellar mass function and the normalization of the observed star formation rate--stellar mass relation to z {approx} 1. The data demands, for example, that the star formation rate density is dominated by galaxies with M{sub star} {approx} 10{sup 10.0-10.5} M{sub {circle_dot}} from 0 < z < 1, and that such galaxies over these epochs reside in halos with M{sub vir} {approx} 10{sup 11.5-12.5} M{sub {circle_dot}}. The star formation rate--halo mass relation is approximately Gaussian over the range 0 < z < 1 with a mildly evolving mean and normalization. This model is then used to shed light on a number of issues, including (1) a clarification of 'downsizing', (2) the lack of a sharp characteristic halo mass at which star formation is truncated, and (3) the dominance of star formation over merging to the stellar

  7. The immitigable nature of assembly bias: the impact of halo definition on assembly bias

    Science.gov (United States)

    Villarreal, Antonio S.; Zentner, Andrew R.; Mao, Yao-Yuan; Purcell, Chris W.; van den Bosch, Frank C.; Diemer, Benedikt; Lange, Johannes U.; Wang, Kuan; Campbell, Duncan

    2017-11-01

    Dark matter halo clustering depends not only on halo mass, but also on other properties such as concentration and shape. This phenomenon is known broadly as assembly bias. We explore the dependence of assembly bias on halo definition, parametrized by spherical overdensity parameter, Δ. We summarize the strength of concentration-, shape-, and spin-dependent halo clustering as a function of halo mass and halo definition. Concentration-dependent clustering depends strongly on mass at all Δ. For conventional halo definitions (Δ ˜ 200 - 600 m), concentration-dependent clustering at low mass is driven by a population of haloes that is altered through interactions with neighbouring haloes. Concentration-dependent clustering can be greatly reduced through a mass-dependent halo definition with Δ ˜ 20 - 40 m for haloes with M200 m ≲ 1012 h-1M⊙. Smaller Δ implies larger radii and mitigates assembly bias at low mass by subsuming altered, so-called backsplash haloes into now larger host haloes. At higher masses (M200 m ≳ 1013 h-1M⊙) larger overdensities, Δ ≳ 600 m, are necessary. Shape- and spin-dependent clustering are significant for all halo definitions that we explore and exhibit a relatively weaker mass dependence. Generally, both the strength and the sense of assembly bias depend on halo definition, varying significantly even among common definitions. We identify no halo definition that mitigates all manifestations of assembly bias. A halo definition that mitigates assembly bias based on one halo property (e.g. concentration) must be mass dependent. The halo definitions that best mitigate concentration-dependent halo clustering do not coincide with the expected average splashback radii at fixed halo mass.

  8. Reconstruction of halo power spectrum from redshift-space galaxy distribution: cylinder-grouping method and halo exclusion effect

    Science.gov (United States)

    Okumura, Teppei; Takada, Masahiro; More, Surhud; Masaki, Shogo

    2017-07-01

    The peculiar velocity field measured by redshift-space distortions (RSD) in galaxy surveys provides a unique probe of the growth of large-scale structure. However, systematic effects arise when including satellite galaxies in the clustering analysis. Since satellite galaxies tend to reside in massive haloes with a greater halo bias, the inclusion boosts the clustering power. In addition, virial motions of the satellite galaxies cause a significant suppression of the clustering power due to non-linear RSD effects. We develop a novel method to recover the redshift-space power spectrum of haloes from the observed galaxy distribution by minimizing the contamination of satellite galaxies. The cylinder-grouping method (CGM) we study effectively excludes satellite galaxies from a galaxy sample. However, we find that this technique produces apparent anisotropies in the reconstructed halo distribution over all the scales which mimic RSD. On small scales, the apparent anisotropic clustering is caused by exclusion of haloes within the anisotropic cylinder used by the CGM. On large scales, the misidentification of different haloes in the large-scale structures, aligned along the line of sight, into the same CGM group causes the apparent anisotropic clustering via their cross-correlation with the CGM haloes. We construct an empirical model for the CGM halo power spectrum, which includes correction terms derived using the CGM window function at small scales as well as the linear matter power spectrum multiplied by a simple anisotropic function at large scales. We apply this model to a mock galaxy catalogue at z = 0.5, designed to resemble Sloan Digital Sky Survey-III Baryon Oscillation Spectroscopic Survey (BOSS) CMASS galaxies, and find that our model can predict both the monopole and quadrupole power spectra of the host haloes up to k < 0.5 {{h Mpc^{-1}}} to within 5 per cent.

  9. ISOTOPE SEPARATORS

    Science.gov (United States)

    Bacon, C.G.

    1958-08-26

    An improvement is presented in the structure of an isotope separation apparatus and, in particular, is concerned with a magnetically operated shutter associated with a window which is provided for the purpose of enabling the operator to view the processes going on within the interior of the apparatus. The shutier is mounted to close under the force of gravity in the absence of any other force. By closing an electrical circuit to a coil mouated on the shutter the magnetic field of the isotope separating apparatus coacts with the magnetic field of the coil to force the shutter to the open position.

  10. Ureilite Carbon and mg Number

    Science.gov (United States)

    Hudon, P.; Romanek, C.; Paddock, L.; Mittlefehldt, D. W.

    2004-05-01

    Ureilites are carbon-bearing ultramafic achondrites composed primarily of olivine and pyroxene with intergranular fine-grained metal, sulfides, and silicates. Carbon (up to 6.5 wt%) is either amorphous or present as graphite, lonsdaleite, and/or diamond. It has been shown that carbon-silicate redox (i.e. "smelting") reactions are responsible for the positive correlation between modal percent pigeonite and mg# and for the negative FeO-MnO trend seen in the mineral and bulk compositions of ureilites. Carbon redox reactions are strongly exothermic and pressure dependent; so ureilites with the largest mg# are the most reduced, experienced the highest temperatures, and formed at the lowest pressures, i.e. near the surface of the ureilite parent body. Ureilites with the largest mg# have the smallest δ 18O and the largest Δ 17O. To further investigate possible relationships, we performed carbon isotope and electron probe measurements on a suite of 27 ureilites in order to see the type of correlation that exists between mg# and carbon. Mg#s of olivine cores, carbon contents, and δ 13C data were taken from this study and the literature, and averaged. Polymict ureilites were not considered. A well-defined negative correlation is observed between the mg# of olivine cores and Δ 17O. A less well-defined negative correlation may exist between mg# of olivine cores and δ 13C, but there is substantial scatter in the data. However, a well-defined negative correlation exists between mg# of olivine rims and δ 13C. At first glance, this trend is unexpected: if ureilites with the largest mg# experienced the greatest amount of reduction, they should have the largest δ 13C and the correlation between mg# and δ 13C should be positive. A plot of carbon content versus δ 13C seems to show a general trend: the smaller the carbon content, the heavier is the carbon. This general trend is exactly what one would expect if smelting has affected the ureilite parent body: the more C is

  11. On the galaxy-halo connection in the EAGLE simulation

    Science.gov (United States)

    Desmond, Harry; Mao, Yao-Yuan; Wechsler, Risa H.; Crain, Robert A.; Schaye, Joop

    2017-10-01

    Empirical models of galaxy formation require assumptions about the correlations between galaxy and halo properties. These may be calibrated against observations or inferred from physical models such as hydrodynamical simulations. In this Letter, we use the EAGLE simulation to investigate the correlation of galaxy size with halo properties. We motivate this analysis by noting that the common assumption of angular momentum partition between baryons and dark matter in rotationally supported galaxies overpredicts both the spread in the stellar mass-size relation and the anticorrelation of size and velocity residuals, indicating a problem with the galaxy-halo connection it implies. We find the EAGLE galaxy population to perform significantly better on both statistics, and trace this success to the weakness of the correlations of galaxy size with halo mass, concentration and spin at fixed stellar mass. Using these correlations in empirical models will enable fine-grained aspects of galaxy scalings to be matched.

  12. Impact of Neutrinos on Dark Matter Halo Environment

    Science.gov (United States)

    Court, Travis; Villaescusa-Navarro, Francisco

    2018-01-01

    The spatial clustering of galaxies is commonly used to infer the shape of the matter power spectrum and therefore to place constraints on the value of the cosmological parameters. In order to extract the maximum information from galaxy surveys it is required to provide accurate theoretical predictions. The first step to model galaxy clustering is to understand the spatial distribution of the structures where they reside: dark matter halos. I will show that the clustering of halos does not depend only on mass, but on other quantities like local matter overdensity. I will point out that halo clustering is also sensitive to the local overdensity of the cosmic neutrino background. I will show that splitting halos according to neutrino overdensity induces a very large scale-dependence bias, an effect that may lead to a new technique to constraint the sum of the neutrino masses.

  13. Visibility of stars, halos, and rainbows during solar eclipses.

    Science.gov (United States)

    Können, Gunther P; Hinz, Claudia

    2008-12-01

    The visibility of stars, planets, diffraction coronas, halos, and rainbows during the partial and total phases of a solar eclipse is studied. The limiting magnitude during various stages of the partial phase is presented. The sky radiance during totality with respect to noneclipse conditions is revisited and found to be typically 1/4000. The corresponding limiting magnitude is +3.5. At totality, the signal-to-background ratio of diffraction coronas, halos, and rainbows has dropped by a factor of 250. It is found that diffraction coronas around the totally eclipsed Sun may nevertheless occur. Analyses of lunar halo observations during twilight indicate that bright halo displays may also persist during totality. Rainbows during totality seem impossible.

  14. Planetary nebulae as kinematic tracers of galaxy stellar halos

    Science.gov (United States)

    Coccato, Lodovico

    2017-10-01

    The kinematic and dynamical properties of galaxy stellar halos are difficult to measure because of the faint surface brightness that characterizes these regions. Spiral galaxies can be probed using the radio Hi emission; on the contrary, early-type galaxies contain less gas, therefore alternative kinematic tracers need to be used. Planetary nebulae (PNe) can be easily detected far out in the halo thanks to their bright emission lines. It is therefore possible to map the halo kinematics also in early-type galaxies, typically out to 5 effective radii or beyond. Thanks to the recent spectroscopic surveys targeting extra-galactic PNe, we can now rely on a few tens of galaxies where the kinematics of the stellar halos are measured. Here, I will review the main results obtained in this field in the last decades.

  15. Halo performance on low light level image intensifiers

    Science.gov (United States)

    Cui, Dongxu; Ren, Ling; Chang, Benkang; Shi, Feng; Shi, Jifang; Qian, Yunsheng; Wang, Honggang; Zhang, Junju

    To analyze the formation mechanism of the halo on low light level image intensifiers and the influencing factors on the halo size, a halo tester has been designed. Under the illumination between 10-2 lx and 10-4 lx, we use the tester to collect a 0.1922 mm hole image directly with CoolSNAPK4 charge-coupled device (CCD) in a darkroom. The practical measurement result shows that the amplification ratio is 343.4. Then we put the super second and third generation image intensifiers after the hole, and the halo sizes of the hole images on the screens are determined as 0.2388 and 0.5533 mm respectively. The results are helpful to improve the quality of the low light level image intensifiers.

  16. Summary of the 2014 Beam-Halo Monitoring Workshop

    Energy Technology Data Exchange (ETDEWEB)

    Fisher, Alan

    2015-09-25

    Understanding and controlling beam halo is important for high-intensity hadron accelerators, for high-brightness electron linacs, and for low-emittance light sources. This can only be achieved by developing suitable diagnostics. The main challenge faced by such instrumentation is the high dynamic range needed to observe the halo in the presence of an intense core. In addition, measurements must often be made non-invasively. This talk summarizes the one-day workshop on Beam-Halo Monitoring that was held at SLAC on September 19 last year, immediately following IBIC 2014 in Monterey. Workshop presentations described invasive techniques using wires, screens, or crystal collimators, and non-invasive measurements with gas or scattered electrons. Talks on optical methods showed the close links between observing halo and astronomical problems like observing the solar corona or directly observing a planet orbiting another star.

  17. UARS Halogen Occultation Experiment (HALOE) Level 3AT V001

    Data.gov (United States)

    National Aeronautics and Space Administration — The Halogen Occultation Experiment (HALOE) Level 3AT data product consists of daily vertical profiles of temperature, aerosol extinction and concentrations of HCl,...

  18. Revisiting Scaling Relations for Giant Radio Halos in Galaxy Clusters

    Science.gov (United States)

    Cassano, R.; Ettori, S.; Brunetti, G.; Giacintucci, S.; Pratt, G. W.; Venturi, T.; Kale, R.; Dolag, K.; Markevitch, Maxim L.

    2013-01-01

    Many galaxy clusters host megaparsec-scale radio halos, generated by ultrarelativistic electrons in the magnetized intracluster medium. Correlations between the synchrotron power of radio halos and the thermal properties of the hosting clusters were established in the last decade, including the connection between the presence of a halo and cluster mergers. The X-ray luminosity and redshift-limited Extended GMRT Radio Halo Survey provides a rich and unique dataset for statistical studies of the halos. We uniformly analyze the radio and X-ray data for the GMRT cluster sample, and use the new Planck Sunyaev-Zel'dovich (SZ) catalog to revisit the correlations between the power of radio halos and the thermal properties of galaxy clusters. We find that the radio power at 1.4 GHz scales with the cluster X-ray (0.1-2.4 keV) luminosity computed within R(sub 500) as P(sub 1.4) approx. L(2.1+/-0.2) - 500). Our bigger and more homogenous sample confirms that the X-ray luminous (L(sub 500) > 5 × 10(exp 44) erg/s)) clusters branch into two populations-radio halos lie on the correlation, while clusters without radio halos have their radio upper limits well below that correlation. This bimodality remains if we excise cool cores from the X-ray luminosities. We also find that P(sub 1.4) scales with the cluster integrated SZ signal within R(sub 500), measured by Planck, as P(sub 1.4) approx. Y(2.05+/-0.28) - 500), in line with previous findings. However, contrary to previous studies that were limited by incompleteness and small sample size, we find that "SZ-luminous" Y(sub 500) > 6×10(exp -5) Mpc(exp 2) clusters show a bimodal behavior for the presence of radio halos, similar to that in the radio-X-ray diagram. Bimodality of both correlations can be traced to clusters dynamics, with radio halos found exclusively in merging clusters. These results confirm the key role of mergers for the origin of giant radio halos, suggesting that they trigger the relativistic particle acceleration.

  19. Testing approximate predictions of displacements of cosmological dark matter halos

    Science.gov (United States)

    Munari, Emiliano; Monaco, Pierluigi; Koda, Jun; Kitaura, Francisco-Shu; Sefusatti, Emiliano; Borgani, Stefano

    2017-07-01

    We present a test to quantify how well some approximate methods, designed to reproduce the mildly non-linear evolution of perturbations, are able to reproduce the clustering of DM halos once the grouping of particles into halos is defined and kept fixed. The following methods have been considered: Lagrangian Perturbation Theory (LPT) up to third order, Truncated LPT, Augmented LPT, MUSCLE and COLA. The test runs as follows: halos are defined by applying a friends-of-friends (FoF) halo finder to the output of an N-body simulation. The approximate methods are then applied to the same initial conditions of the simulation, producing for all particles displacements from their starting position and velocities. The position and velocity of each halo are computed by averaging over the particles that belong to that halo, according to the FoF halo finder. This procedure allows us to perform a well-posed test of how clustering of the matter density and halo density fields are recovered, without asking to the approximate method an accurate reconstruction of halos. We have considered the results at z=0,0.5,1, and we have analysed power spectrum in real and redshift space, object-by-object difference in position and velocity, density Probability Distribution Function (PDF) and its moments, phase difference of Fourier modes. We find that higher LPT orders are generally able to better reproduce the clustering of halos, while little or no improvement is found for the matter density field when going to 2LPT and 3LPT. Augmentation provides some improvement when coupled with 2LPT, while its effect is limited when coupled with 3LPT. Little improvement is brought by MUSCLE with respect to Augmentation. The more expensive particle-mesh code COLA outperforms all LPT methods, and this is true even for mesh sizes as large as the inter-particle distance. This test sets an upper limit on the ability of these methods to reproduce the clustering of halos, for the cases when these objects are

  20. Vaporization in comets - The icy grain halo of Comet West

    Science.gov (United States)

    Ahearn, M. F.; Cowan, J. J.

    1980-01-01

    The variation with heliocentric distance of the production rates of various species in Comet West (1975n = 1976 VI) is explained with a cometary model consisting of a CO2 dominated nucleus plus a halo of icy grains of H2O or clathrate hydrate. It is concluded that the parents of CN and C3 are released primarily from the nucleus but that the parent of C2 is released primarily from the halo of icy grains.

  1. Integrated Marketing Communications (IMC) Di PT Halo Rumah Bernyanyi

    OpenAIRE

    Rismayanti, Rebekka

    2016-01-01

    : This research aims to describe the effectiveness of Integrated Marketing Communication (IMC) in PT Halo Rumah Bernyanyi which, from the perspective of marketing strategy, could be studied by analyzing the segmentation, targeting, and positioning. Using case-study method with in-depth interview, the result shows that the implementation of IMC at PT Halo Rumah Bernyayi is arranged in one single strategy and tend to neglect the complexities of running multi-brand family karaoke-house. This con...

  2. Integrated Marketing Communications (IMC) di PT Halo Rumah Bernyanyi

    OpenAIRE

    Rebekka Rismayanti

    2017-01-01

    Abstract: This research aims to describe the effectiveness of Integrated Marketing Communication (IMC) in PT Halo Rumah Bernyanyi which, from the perspective of marketing strategy, could be studied by analyzing the segmentation, targeting, and positioning. Using case-study method with in-depth interview, the result shows that the implementation of IMC at PT Halo Rumah Bernyayi is arranged in one single strategy and tend to neglect the complexities of running multi-brand family karaoke-house. ...

  3. Non-Gaussianity and Excursion Set Theory: Halo Bias

    Energy Technology Data Exchange (ETDEWEB)

    Adshead, Peter [Enrico Fermi Institute, Univ. of Chicago, IL (United States); Baxter, Eric J. [Univ. of Chicago, Chicago, IL (United States); Dodelson, Scott [Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Lidz, Adam [Univ. of Pennsylvania, Philadelphia, PA (United States)

    2012-09-01

    We study the impact of primordial non-Gaussianity generated during inflation on the bias of halos using excursion set theory. We recapture the familiar result that the bias scales as $k^{-2}$ on large scales for local type non-Gaussianity but explicitly identify the approximations that go into this conclusion and the corrections to it. We solve the more complicated problem of non-spherical halos, for which the collapse threshold is scale dependent.

  4. MD 1691: Active halo control using tune ripple at injection

    CERN Document Server

    Garcia Morales, Hector; Bruce, Roderik; Redaelli, Stefano; Fitterer, Miriam; Fiascaris, Maria; Nisbet, David; Thiesen, Hugues; Valentino, Gianluca; Xu, Chen; CERN. Geneva. ATS Department

    2017-01-01

    In this MD we performed halo excitation through tune ripple. This consists in an excitation that introduces new resonance sidebands around the existing resonance lines. In presence of sufficient detuning with amplitude, these sidebands can in principle affect only the dynamics of the halo particles at large amplitudes. Tune ripple was induced through a current modulation of the warm trim quadrupoles in IR7. This is the first time this method is experimentally tested at the LHC.

  5. Nano-mechanics of HaloTag Tethers

    OpenAIRE

    Popa, Ionel; Berkovich, Ronen; Alegre-Cebollada, Jorge; Badilla, Carmen L.; Rivas-Pardo, Jaime Andres; Taniguchi, Yukinori; Kawakami, Masaru; Fernandez, Julio M.

    2013-01-01

    The active site of the Haloalkane Dehydrogenase (HaloTag) enzyme can be covalently attached to a chloroalkane ligand providing a mechanically strong tether, resistant to large pulling forces. Here we demonstrate the covalent tethering of protein L and I27 polyproteins between an AFM cantilever and a glass surface using HaloTag anchoring at one end, and thiol chemistry at the other end. Covalent tethering is unambiguously confirmed by the observation of full length polyprotein unfolding, combi...

  6. Two Stellar Components in the Halo of the Milky Way

    Science.gov (United States)

    2007-12-13

    distributed throughout the primordial interstellar medium by stellar winds and supernovae . Previous work has provided evidence that the halo of the Milky...the number of stars), for samples in which a counter-rotating halo has been claimed, ordered by sample size. The samples listed in the first column...sample by the authors are listed in the third column (see original papers for details). The method of analysis used for each determination is listed : F&W

  7. The globular cluster-dark matter halo connection

    Science.gov (United States)

    Boylan-Kolchin, Michael

    2017-12-01

    I present a simple phenomenological model for the observed linear scaling of the stellar mass in old globular clusters (GCs) with $z=0$ halo mass in which the stellar mass in GCs scales linearly with progenitor halo mass at $z=6$ above a minimum halo mass for GC formation. This model reproduces the observed $M_{\\rm GCs}-M_{\\rm halo}$ relation at $z=0$ and results in a prediction for the minimum halo mass at $z=6$ required for hosting one GC: $M_{\\rm min}(z=6)=1.07 \\times 10^9\\,M_{\\odot}$. Translated to $z=0$, the mean threshold mass is $M_{\\rm halo}(z=0) \\approx 2\\times 10^{10}\\,M_{\\odot}$. I explore the observability of GCs in the reionization era and their contribution to cosmic reionization, both of which depend sensitively on the (unknown) ratio of GC birth mass to present-day stellar mass, $\\xi$. Based on current detections of $z \\gtrsim 6$ objects with $M_{1500} 10$ are strongly disfavored; this, in turn, has potentially important implications for GC formation scenarios. Even for low values of $\\xi$, some observed high-$z$ galaxies may actually be GCs, complicating estimates of reionization-era galaxy ultraviolet luminosity functions and constraints on dark matter models. GCs are likely important reionization sources if $5 \\lesssim \\xi \\lesssim 10$. I also explore predictions for the fraction of accreted versus in situ GCs in the local Universe and for descendants of systems at the halo mass threshold of GC formation (dwarf galaxies). An appealing feature of the model presented here is the ability to make predictions for GC properties based solely on dark matter halo merger trees.

  8. Measuring one nucleon transfer reaction 24Mg( p, d)23Mg for astrophysical reaction rates

    Science.gov (United States)

    Lee, E. J.; Chae, K. Y.

    2017-12-01

    The level structure of a radionuclide 23Mg has been studied by using the 24Mg( p, d)23Mg one nucleon transfer reaction measurement for the astrophysical 19Ne(α, γ)23Mg reaction rate. A 41 MeV proton beam was produced and accelerated at the 25 MV tandem accelerator of the Holifield Radioactive Ion Beam Facility of the Oak Ridge National Laboratory in the United States. The beam particles impinged on an isotopically-enriched 24Mg solid target. Angular distributions of recoiling deuterons were extracted by using a large area silicon strip detector array. By comparing the experimentally-obtained angular distributions with zero range distorted wave Born approximation calculations, spins and parities of three energy levels of 23Mg could be constrained for the first time, which is very important information needed to understand the 19Ne(α, γ)23Mg reaction rate.

  9. Stable isotope

    African Journals Online (AJOL)

    Results of the study suggest that there are two main carbon pathways for plankton and nekton in the Kariega estuary, carbon derived from the eelgrass and its associated epiphytes and carbon which has its origins in the salt marsh riparian vegetation and zooplankton. Keywords: stable isotope analysis; temperate estuary; ...

  10. The abundance and environment of dark matter haloes

    Science.gov (United States)

    Metuki, Ofer; Libeskind, Noam I.; Hoffman, Yehuda

    2016-07-01

    An open question in cosmology and the theory of structure formation is to what extent does environment affect the properties of galaxies and haloes. The present paper aims at shedding light on this problem. The paper focuses on the analysis of a dark matter only simulation and it addresses the issue of how the environment affects the abundance of haloes, which are assigned four attributes: their virial mass, an ambient density calculated with an aperture that scales with Rvir (ΔM), a fixed-aperture (ΔR) ambient density, and a cosmic web classification (i.e. voids, sheets, filaments, and knots, as defined by the V-web algorithm). ΔM is the mean density around a halo evaluated within a sphere of a radius of 5Rvir, where Rvir is the virial radius. ΔR is the density field Gaussian smoothed with R = 4 h-1 Mpc, evaluated at the centre of the halo. The main result of the paper is that the difference between haloes in different web elements stems from the difference in their mass functions, and does not depend on their adaptive-aperture ambient density. A dependence on the fixed-aperture ambient density is induced by the cross-correlation between the mass of a halo and its fixed-aperture ambient density.

  11. Stellar-to-halo mass relation of cluster galaxies

    Science.gov (United States)

    Niemiec, Anna; Jullo, Eric; Limousin, Marceau; Giocoli, Carlo; Erben, Thomas; Hildebrant, Hendrik; Kneib, Jean-Paul; Leauthaud, Alexie; Makler, Martin; Moraes, Bruno; Pereira, Maria E. S.; Shan, Huanyuan; Rozo, Eduardo; Rykoff, Eli; Van Waerbeke, Ludovic

    2017-10-01

    In the formation of galaxy groups and clusters, the dark matter haloes containing satellite galaxies are expected to be tidally stripped in gravitational interactions with the host. We use galaxy-galaxy weak lensing to measure the average mass of dark matter haloes of satellite galaxies as a function of projected distance to the centre of the host, since stripping is expected to be greater for satellites closer to the centre of the cluster. We further classify the satellites according to their stellar mass: Assuming that the stellar component of the galaxy is less disrupted by tidal stripping, stellar mass can be used as a proxy of the infall mass. We study the stellar-to-halo mass relation of satellites as a function of the cluster-centric distance to measure tidal stripping. We use the shear catalogues of the Dark Energy Survey (DES) science verification archive, the Canada-France-Hawaii Lensing Survey (CFHTLenS) and the CFHT Stripe 82 surveys, and we select satellites from the redMaPPer catalogue of clusters. For galaxies located in the outskirts of clusters, we find a stellar-to- halo mass relation in good agreement with the theoretical expectations from Moster et al. for central galaxies. In the centre of the cluster, we find that this relation is shifted to smaller halo mass for a given stellar mass. We interpret this finding as further evidence for tidal stripping of dark matter haloes in high-density environments.

  12. Nano-mechanics of HaloTag Tethers

    Science.gov (United States)

    Popa, Ionel; Berkovich, Ronen; Alegre-Cebollada, Jorge; Badilla, Carmen L.; Rivas-Pardo, Jaime Andres; Taniguchi, Yukinori; Kawakami, Masaru; Fernandez, Julio M.

    2013-01-01

    The active site of the Haloalkane Dehydrogenase (HaloTag) enzyme can be covalently attached to a chloroalkane ligand providing a mechanically strong tether, resistant to large pulling forces. Here we demonstrate the covalent tethering of protein L and I27 polyproteins between an AFM cantilever and a glass surface using HaloTag anchoring at one end, and thiol chemistry at the other end. Covalent tethering is unambiguously confirmed by the observation of full length polyprotein unfolding, combined with high detachment forces that range up to ~2000 pN. We use these covalently anchored polyproteins to study the remarkable mechanical properties of HaloTag proteins. We show that the force that triggers unfolding of the HaloTag protein exhibits a four-fold increase, from 131 pN to 491 pN, when the direction of the applied force is changed from the C-terminus to the N-terminus. Force-clamp experiments reveal that unfolding of the HaloTag protein is twice more sensitive to pulling force compared to protein L, and refolds at a slower rate. We show how these properties allow for the long-term observation of protein folding-unfolding cycles at high forces, without interference from the HaloTag tether. PMID:23909704

  13. What to expect from dynamical modelling of galactic haloes

    Science.gov (United States)

    Wang, Wenting; Han, Jiaxin; Cole, Shaun; Frenk, Carlos; Sawala, Till

    2017-09-01

    Many dynamical models of the Milky Way halo require assumptions that the distribution function of a tracer population should be independent of time (I.e. a steady-state distribution function) and that the underlying potential is spherical. We study the limitations of such modelling by applying a general dynamical model with minimal assumptions to a large sample of galactic haloes from cosmological N-body and hydrodynamical simulations. Using dark matter particles as dynamical tracers, we find that the systematic uncertainties in the measured mass and concentration parameters typically have an amplitude of 25-40 per cent. When stars are used as tracers, however, the systematic uncertainties can be as large as a factor of 2-3. The systematic uncertainties are not reduced by increasing the tracer sample size and vary stochastically from halo to halo. These systematic uncertainties are mostly driven by underestimated statistical noise caused by correlated phase-space structures that violate the steady-state assumption. The number of independent phase-space structures inferred from the uncertainty level sets a limiting sample size beyond which a further increase no longer significantly improves the accuracy of dynamical inferences. The systematic uncertainty level is determined by the halo merger history, the shape and environment of the halo. Our conclusions apply generally to any spherical steady-state model.

  14. Cold dark matter. 1: The formation of dark halos

    Science.gov (United States)

    Gelb, James M.; Bertschinger, Edmund

    1994-01-01

    We use numerical simulations of critically closed cold dark matter (CDM) models to study the effects of numerical resolution on observable quantities. We study simulations with up to 256(exp 3) particles using the particle-mesh (PM) method and with up to 144(exp 3) particles using the adaptive particle-particle-mesh (P3M) method. Comparisons of galaxy halo distributions are made among the various simulations. We also compare distributions with observations, and we explore methods for identifying halos, including a new algorithm that finds all particles within closed contours of the smoothed density field surrounding a peak. The simulated halos show more substructure than predicted by the Press-Schechter theory. We are able to rule out all omega = 1 CDM models for linear amplitude sigma(sub 8) greater than or approximately = 0.5 because the simulations produce too many massive halos compared with the observations. The simulations also produce too many low-mass halos. The distribution of halos characterized by their circular velocities for the P3M simulations is in reasonable agreement with the observations for 150 km/s less than or = V(sub circ) less than or = 350 km/s.

  15. Design of CMS Beam Halo Monitor system

    CERN Document Server

    AUTHOR|(CDS)2078842

    2015-01-01

    A fast and directional monitoring system for the CMS experiment is designed to provide an online, bunch-by-bunch measurement of beam background induced by beam halo interactions, separately for each beam. The background detection is based on Cherenkov radiation produced in synthetic fused silica read out by a fast, UV sensitive photomultiplier tube. Twenty detector units per end will be azimuthally distributed around the rotating shielding of CMS, covering ~408 cm2 at 20.6m from the interaction point, at a radius of ~180 cm. The directional and fast response of the system allows the discrimination of the background particles from the dominant flux in the cavern induced by pp collision debris, produced within the 25 ns bunch spacing. A robust multi-layered shielding will enclose each detector unit to protect the photomultiplier tube from the magnetic field and to eliminate the occupancy from low energy particles. The design of the front-end units is validated by experimental results. An overview of the new sy...

  16. The CMS Beam Halo Monitor electronics

    Science.gov (United States)

    Tosi, N.; Dabrowski, A. E.; Fabbri, F.; Grassi, T.; Hughes, E.; Mans, J.; Montanari, A.; Orfanelli, S.; Rusack, R.; Torromeo, G.; Stickland, D. P.; Stifter, K.

    2016-02-01

    The CMS Beam Halo Monitor has been successfully installed in the CMS cavern in LHC Long Shutdown 1 for measuring the machine induced background for LHC Run II. The system is based on 40 detector units composed of synthetic quartz Cherenkov radiators coupled to fast photomultiplier tubes (PMTs). The readout electronics chain uses many components developed for the Phase 1 upgrade to the CMS Hadronic Calorimeter electronics, with dedicated firmware and readout adapted to the beam monitoring requirements. The PMT signal is digitized by a charge integrating ASIC (QIE10), providing both the signal rise time, with few nanosecond resolution, and the charge integrated over one bunch crossing. The backend electronics uses microTCA technology and receives data via a high-speed 5 Gbps asynchronous link. It records histograms with sub-bunch crossing timing resolution and is read out via IPbus using the newly designed CMS data acquisition for non-event based data. The data is processed in real time and published to CMS and the LHC, providing online feedback on the beam quality. A dedicated calibration monitoring system has been designed to generate short triggered pulses of light to monitor the efficiency of the system. The electronics has been in operation since the first LHC beams of Run II and has served as the first demonstration of the new QIE10, Microsemi Igloo2 FPGA and high-speed 5 Gbps link with LHC data.

  17. Beam halo collimation in heavy ion synchrotrons

    Directory of Open Access Journals (Sweden)

    I. Strašík

    2015-08-01

    Full Text Available This paper presents a systematic study of the halo collimation of ion beams from proton up to uranium in synchrotrons. The projected Facility for Antiproton and Ion Research synchrotron SIS100 is used as a reference case. The concepts are separated into fully stripped (e.g., ^{238}U^{92+} and partially stripped (e.g., ^{238}U^{28+} ion collimation. An application of the two-stage betatron collimation system, well established for proton accelerators, is intended also for fully stripped ions. The two-stage system consists of a primary collimator (a scattering foil and secondary collimators (bulky absorbers. Interaction of the particles with the primary collimator (scattering, momentum losses, and nuclear interactions was simulated by using fluka. Particle-tracking simulations were performed by using mad-x. Finally, the dependence of the collimation efficiency on the primary ion species was determined. The influence of the collimation system adjustment, lattice imperfections, and beam parameters was estimated. The concept for the collimation of partially stripped ions employs a thin stripping foil in order to change their charge state. These ions are subsequently deflected towards a dump location using a beam optical element. The charge state distribution after the stripping foil was obtained from global. The ions were tracked by using mad–x.

  18. Performance of the CMS Beam Halo Monitor

    CERN Document Server

    CMS Collaboration

    2015-01-01

    The CMS Beam Halo Monitor has been successfully installed in the CMS cavern in LHC Long Shutdown 1 for measuring the machine induced background for LHC Run II. The system is based on 40 detector units composed of radiation hard synthetic quartz Cherenkov radiators coupled to fast photomultiplier tubes for a direction sensitive measurement. The readout electronics chain uses many components developed for the Phase 1 upgrade to the CMS Hadronic Calorimeter electronics, with dedicated firmware and readout adapted to the beam monitoring requirements. The PMT signal is digitized by a charge integrating ASIC (QIE10), providing both the signal rise time, with few ns resolution, and the charge integrated over one bunch crossing. The backend electronics uses microTCA technology and received data via a high-speed 5 Gbps asynchronous link. It records histograms with sub-bunch crossing timing resolution and is readout by IPbus using the newly designed CMS data acquisition for non-event based data. The data is processed i...

  19. The CMS Beam Halo Monitor Electronics

    CERN Document Server

    AUTHOR|(CDS)2080684; Fabbri, F.; Grassi, T.; Hughes, E.; Mans, J.; Montanari, A.; Orfanelli, S.; Rusack, R.; Torromeo, G.; Stickland, D.P.; Stifter, K.

    2016-01-01

    The CMS Beam Halo Monitor has been successfully installed in the CMS cavern in LHC Long Shutdown 1 for measuring the machine induced background for LHC Run II. The system is based on 40 detector units composed of synthetic quartz Cherenkov radiators coupled to fast photomultiplier tubes. The readout electronics chain uses many components developed for the Phase 1 upgrade to the CMS Hadronic Calorimeter electronics, with dedicated firmware and readout adapted to the beam monitoring requirements. The PMT signal is digitized by a charge integrating ASIC (QIE10), providing both the signal rise time, with few ns resolution, and the charge integrated over one bunch crossing. The backend electronics uses microTCA technology and receives data via a high-speed 5 Gbps asynchronous link. It records histograms with sub-bunch crossing timing resolution and is readout by IPbus using the newly designed CMS data acquisition for non-event based data. The data is processed in real time and published to CMS and the LHC, providi...

  20. HaloPROTACS: Use of Small Molecule PROTACs to Induce Degradation of HaloTag Fusion Proteins.

    Science.gov (United States)

    Buckley, Dennis L; Raina, Kanak; Darricarrere, Nicole; Hines, John; Gustafson, Jeffrey L; Smith, Ian E; Miah, Afjal H; Harling, John D; Crews, Craig M

    2015-08-21

    Small molecule-induced protein degradation is an attractive strategy for the development of chemical probes. One method for inducing targeted protein degradation involves the use of PROTACs, heterobifunctional molecules that can recruit specific E3 ligases to a desired protein of interest. PROTACs have been successfully used to degrade numerous proteins in cells, but the peptidic E3 ligase ligands used in previous PROTACs have hindered their development into more mature chemical probes or therapeutics. We report the design of a novel class of PROTACs that incorporate small molecule VHL ligands to successfully degrade HaloTag7 fusion proteins. These HaloPROTACs will inspire the development of future PROTACs with more drug-like properties. Additionally, these HaloPROTACs are useful chemical genetic tools, due to their ability to chemically knock down widely used HaloTag7 fusion proteins in a general fashion.

  1. Measurement of isotope abundance variations in nature by gravimetric spiking isotope dilution analysis (GS-IDA).

    Science.gov (United States)

    Chew, Gina; Walczyk, Thomas

    2013-04-02

    Subtle variations in the isotopic composition of elements carry unique information about physical and chemical processes in nature and are now exploited widely in diverse areas of research. Reliable measurement of natural isotope abundance variations is among the biggest challenges in inorganic mass spectrometry as they are highly sensitive to methodological bias. For decades, double spiking of the sample with a mix of two stable isotopes has been considered the reference technique for measuring such variations both by multicollector-inductively coupled plasma mass spectrometry (MC-ICPMS) and multicollector-thermal ionization mass spectrometry (MC-TIMS). However, this technique can only be applied to elements having at least four stable isotopes. Here we present a novel approach that requires measurement of three isotope signals only and which is more robust than the conventional double spiking technique. This became possible by gravimetric mixing of the sample with an isotopic spike in different proportions and by applying principles of isotope dilution for data analysis (GS-IDA). The potential and principle use of the technique is demonstrated for Mg in human urine using MC-TIMS for isotopic analysis. Mg is an element inaccessible to double spiking methods as it consists of three stable isotopes only and shows great potential for metabolically induced isotope effects waiting to be explored.

  2. Electronic structure and superconductivity of MgB2

    Indian Academy of Sciences (India)

    Unknown

    type structure, where B atoms form a primitive honey- comb lattice consisting of graphite-like sheets separated by hexagonal layers of Mg atoms. Boron isotope effect. (Bud'ko et al 2001) has been observed in MgB2 giving credence to the belief that the pairing mechanism leading to superconductivity is of phononic origin.

  3. Oxygen isotope fractionation in double carbonates.

    Science.gov (United States)

    Zheng, Yong-Fei; Böttcher, Michael E

    2016-01-01

    Oxygen isotope fractionations in double carbonates of different crystal structures were calculated by the increment method. Synthesis experiments were performed at 60 °C and 100 °C to determine oxygen and carbon isotope fractionations involving PbMg[CO3]2. The calculations suggest that the double carbonates of calcite structure are systematically enriched in (18)O relative to those of aragonite and mixture structures. Internally consistent oxygen isotope fractionation factors are obtained for these minerals with respect to quartz, calcite and water at a temperature range of 0-1200 °C. The calculated fractionation factors for double carbonate-water systems are generally consistent with the data available from laboratory experiments. The experimentally determined fractionation factors for PbMg[CO3]2, BaMg[CO3]2 and CaMg[CO3]2 against H2O not only fall between fractionation factors involving pure carbonate end-members but are also close to the calculated fractionation factors. In contrast, experimentally determined carbon isotope fractionation factors between PbMg[CO3]2 and CO2 are much closer to theoretical predictions for the cerussite-CO2 system than for the magnesite-CO2 system, similar to the fractionation behavior for BaMg[CO3]2. Therefore, the combined theoretical and experimental results provide insights into the effects of crystal structure and exchange kinetics on oxygen isotope partitioning in double carbonates.

  4. The shape of the invisible halo: N-body simulations on parallel supercomputers

    Energy Technology Data Exchange (ETDEWEB)

    Warren, M.S.; Zurek, W.H. (Los Alamos National Lab., NM (USA)); Quinn, P.J. (Australian National Univ., Canberra (Australia). Mount Stromlo and Siding Spring Observatories); Salmon, J.K. (California Inst. of Tech., Pasadena, CA (USA))

    1990-01-01

    We study the shapes of halos and the relationship to their angular momentum content by means of N-body (N {approximately} 10{sup 6}) simulations. Results indicate that in relaxed halos with no apparent substructure: (i) the shape and orientation of the isodensity contours tends to persist throughout the virialised portion of the halo; (ii) most ({approx}70%) of the halos are prolate; (iii) the approximate direction of the angular momentum vector tends to persist throughout the halo; (iv) for spherical shells centered on the core of the halo the magnitude of the specific angular momentum is approximately proportional to their radius; (v) the shortest axis of the ellipsoid which approximates the shape of the halo tends to align with the rotation axis of the halo. This tendency is strongest in the fastest rotating halos. 13 refs., 4 figs.

  5. Si isotope homogeneity of the solar nebula

    Energy Technology Data Exchange (ETDEWEB)

    Pringle, Emily A.; Savage, Paul S.; Moynier, Frédéric [Department of Earth and Planetary Sciences and McDonnell Center for the Space Sciences, Washington University in St. Louis, One Brookings Drive, St. Louis, MO 63130 (United States); Jackson, Matthew G. [Department of Earth Science, University of California, Santa Barbara, CA 93109 (United States); Barrat, Jean-Alix, E-mail: eapringle@wustl.edu, E-mail: savage@levee.wustl.edu, E-mail: pringle@ipgp.fr, E-mail: moynier@ipgp.fr, E-mail: jackson@geol.ucsb.edu, E-mail: Jean-Alix.Barrat@univ-brest.fr [Université Européenne de Bretagne, Université de Brest, CNRS UMR 6538 (Domaines Océaniques), I.U.E.M., Place Nicolas Copernic, F-29280 Plouzané Cedex (France)

    2013-12-20

    The presence or absence of variations in the mass-independent abundances of Si isotopes in bulk meteorites provides important clues concerning the evolution of the early solar system. No Si isotopic anomalies have been found within the level of analytical precision of 15 ppm in {sup 29}Si/{sup 28}Si across a wide range of inner solar system materials, including terrestrial basalts, chondrites, and achondrites. A possible exception is the angrites, which may exhibit small excesses of {sup 29}Si. However, the general absence of anomalies suggests that primitive meteorites and differentiated planetesimals formed in a reservoir that was isotopically homogenous with respect to Si. Furthermore, the lack of resolvable anomalies in the calcium-aluminum-rich inclusion measured here suggests that any nucleosynthetic anomalies in Si isotopes were erased through mixing in the solar nebula prior to the formation of refractory solids. The homogeneity exhibited by Si isotopes may have implications for the distribution of Mg isotopes in the solar nebula. Based on supernova nucleosynthetic yield calculations, the expected magnitude of heavy-isotope overabundance is larger for Si than for Mg, suggesting that any potential Mg heterogeneity, if present, exists below the 15 ppm level.

  6. HaloTag as a reporter gene: positron emission tomography imaging with 64Cu-labeled second generation HaloTag ligands

    OpenAIRE

    Hong, Hao; Benink, Hélène A.; Uyeda, H. Tetsuo; Valdovinos, Hector F.; Zhang, Yin; Meisenheimer, Poncho; Barnhart, Todd E.; Fan, Frank; Cai, Weibo

    2013-01-01

    The goal of this study is to employ the HaloTag technology for positron emission tomography (PET), which involves two components: the HaloTag protein (a modified hydrolase which covalently binds to synthetic ligands) and HaloTag ligands (HTLs). 4T1 murine breast cancer cells were stably transfected to express HaloTag protein on the surface (termed as 4T1-HaloTag-ECS, ECS denotes extracellular surface). Two new HTLs were synthesized and termed NOTA-HTL2G-S and NOTA-HTL2G-L (2G indicates second...

  7. Halo formation and evolution: unifying physical properties with structure

    Science.gov (United States)

    Ernest, Alllan David; Collins, Matthew P.

    2015-08-01

    The assembly of matter in the universe proliferates a variety of structures with diverse properties. For example, massive halos of clusters of galaxies have temperatures often an order of magnitude or more higher than the individual galaxy halos within the cluster, or the temperatures of isolated galaxy halos. Giant spiral galaxies contain large quantities of both dark matter and hot gas while other structures like globular clusters appear to have little or no dark matter or gas. Still others, like the dwarf spheroidal galaxies have low gravity and little hot gas, but ironically contain some of the largest fractions of dark matter in the universe. Star forming rates (SFRs) also vary: compare for example the SFRs of giant elliptical galaxies, globular clusters, spiral and starburst galaxies. Furthermore there is evidence that the various structure types have existed over a large fraction of cosmic history. How can this array of variation in properties be reconciled with galaxy halo formation and evolution?We propose a model of halo formation [1] and evolution [2] that is consistent with both primordial nucleosynthesis (BBN) and the isotropies in the cosmic microwave background (CMB). The model uses two simple parameters, the total mass and size of a structure, to (1) explain why galaxies have the fractions of dark matter that they do (including why dwarf spheroidals are so dark matter dominated despite their weak gravity), (2) enable an understanding of the black hole-bulge/black hole-dark halo relations, (3) explain how fully formed massive galaxies can occur so early in cosmic history, (4) understand the connection between spiral and elliptical galaxies (5) unify the nature of globular clusters, dwarf spheroidal galaxies and bulges and (6) predict the temperatures of hot gas halos and understand how cool galaxy halos can remain stable in the hot environments of cluster-galaxy halos.[1] Ernest, A. D., 2012, in Prof. Ion Cotaescu (Ed) Advances in Quantum Theory, pp

  8. The Angular Momentum of Baryons and Dark Matter Halos Revisited

    Science.gov (United States)

    Kimm, Taysun; Devriendt, Julien; Slyz, Adrianne; Pichon, Christophe; Kassin, Susan A.; Dubois, Yohan

    2011-01-01

    Recent theoretical studies have shown that galaxies at high redshift are fed by cold, dense gas filaments, suggesting angular momentum transport by gas differs from that by dark matter. Revisiting this issue using high-resolution cosmological hydrodynamics simulations with adaptive-mesh refinement (AMR), we find that at the time of accretion, gas and dark matter do carry a similar amount of specific angular momentum, but that it is systematically higher than that of the dark matter halo as a whole. At high redshift, freshly accreted gas rapidly streams into the central region of the halo, directly depositing this large amount of angular momentum within a sphere of radius r = 0.1R(sub vir). In contrast, dark matter particles pass through the central region unscathed, and a fraction of them ends up populating the outer regions of the halo (r/R(sub vir) > 0.1), redistributing angular momentum in the process. As a result, large-scale motions of the cosmic web have to be considered as the origin of gas angular momentum rather than its virialised dark matter halo host. This generic result holds for halos of all masses at all redshifts, as radiative cooling ensures that a significant fraction of baryons remain trapped at the centre of the halos. Despite this injection of angular momentum enriched gas, we predict an amount for stellar discs which is in fair agreement with observations at z=0. This arises because the total specific angular momentum of the baryons (gas and stars) remains close to that of dark matter halos. Indeed, our simulations indicate that any differential loss of angular momentum amplitude between the two components is minor even though dark matter halos continuously lose between half and two-thirds of their specific angular momentum modulus as they evolve. In light of our results, a substantial revision of the standard theory of disc formation seems to be required. We propose a new scenario where gas efficiently carries the angular momentum generated

  9. HaloTag technology: a versatile platform for biomedical applications.

    Science.gov (United States)

    England, Christopher G; Luo, Haiming; Cai, Weibo

    2015-06-17

    Exploration of protein function and interaction is critical for discovering links among genomics, proteomics, and disease state; yet, the immense complexity of proteomics found in biological systems currently limits our investigational capacity. Although affinity and autofluorescent tags are widely employed for protein analysis, these methods have been met with limited success because they lack specificity and require multiple fusion tags and genetic constructs. As an alternative approach, the innovative HaloTag protein fusion platform allows protein function and interaction to be comprehensively analyzed using a single genetic construct with multiple capabilities. This is accomplished using a simplified process, in which a variable HaloTag ligand binds rapidly to the HaloTag protein (usually linked to the protein of interest) with high affinity and specificity. In this review, we examine all current applications of the HaloTag technology platform for biomedical applications, such as the study of protein isolation and purification, protein function, protein-protein and protein-DNA interactions, biological assays, in vitro cellular imaging, and in vivo molecular imaging. In addition, novel uses of the HaloTag platform are briefly discussed along with potential future applications.

  10. Deep brain transcranial magnetic stimulation using variable "Halo coil" system

    Science.gov (United States)

    Meng, Y.; Hadimani, R. L.; Crowther, L. J.; Xu, Z.; Qu, J.; Jiles, D. C.

    2015-05-01

    Transcranial Magnetic Stimulation has the potential to treat various neurological disorders non-invasively and safely. The "Halo coil" configuration can stimulate deeper regions of the brain with lower surface to deep-brain field ratio compared to other coil configurations. The existing "Halo coil" configuration is fixed and is limited in varying the site of stimulation in the brain. We have developed a new system based on the current "Halo coil" design along with a graphical user interface system that enables the larger coil to rotate along the transverse plane. The new system can also enable vertical movement of larger coil. Thus, this adjustable "Halo coil" configuration can stimulate different regions of the brain by adjusting the position and orientation of the larger coil on the head. We have calculated magnetic and electric fields inside a MRI-derived heterogeneous head model for various positions and orientations of the coil. We have also investigated the mechanical and thermal stability of the adjustable "Halo coil" configuration for various positions and orientations of the coil to ensure safe operation of the system.

  11. Halo-Independent Direct Detection Analyses Without Mass Assumptions

    CERN Document Server

    Anderson, Adam J.; Kahn, Yonatan; McCullough, Matthew

    2015-10-06

    Results from direct detection experiments are typically interpreted by employing an assumption about the dark matter velocity distribution, with results presented in the $m_\\chi-\\sigma_n$ plane. Recently methods which are independent of the DM halo velocity distribution have been developed which present results in the $v_{min}-\\tilde{g}$ plane, but these in turn require an assumption on the dark matter mass. Here we present an extension of these halo-independent methods for dark matter direct detection which does not require a fiducial choice of the dark matter mass. With a change of variables from $v_{min}$ to nuclear recoil momentum ($p_R$), the full halo-independent content of an experimental result for any dark matter mass can be condensed into a single plot as a function of a new halo integral variable, which we call $\\tilde{h}(p_R)$. The entire family of conventional halo-independent $\\tilde{g}(v_{min})$ plots for all DM masses are directly found from the single $\\tilde{h}(p_R)$ plot through a simple re...

  12. Properties of dark matter haloes as a function of local environment density

    Science.gov (United States)

    Lee, Christoph T.; Primack, Joel R.; Behroozi, Peter; Rodríguez-Puebla, Aldo; Hellinger, Doug; Dekel, Avishai

    2017-04-01

    We study how properties of discrete dark matter haloes depend on halo environment, characterized by the mass density around the haloes on scales from 0.5 to 16 h-1 Mpc. We find that low-mass haloes (those less massive than the characteristic mass MC of haloes collapsing at a given epoch) in high-density environments have lower accretion rates, lower spins, higher concentrations and rounder shapes than haloes in median density environments. Haloes in median- and low-density environments have similar accretion rates and concentrations, but haloes in low-density environments have lower spins and are more elongated. Haloes of a given mass in high-density regions accrete material earlier than haloes of the same mass in lower density regions. All but the most massive haloes in high-density regions are losing mass (i.e. being stripped) at low redshifts, which causes artificially lowered NFW scale radii and increased concentrations. Tidal effects are also responsible for the decreasing spins of low-mass haloes in high-density regions at low redshifts z spins because they lack nearby haloes whose tidal fields can spin them up. We also show that the simulation density distribution is well fit by an extreme value distribution, and that the density distribution becomes broader with cosmic time.

  13. Subdural abscess associated with halo-pin traction.

    Science.gov (United States)

    Garfin, S R; Botte, M J; Triggs, K J; Nickel, V L

    1988-10-01

    Osteomyelitis and intracranial abscess are among the most serious complications that have been reported in association with the use of the halo device. The cases of five patients who had formation of an intracranial abscess related to the use of a halo cervical immobilizer are described. All of the infections resolved after drainage of the abscess, débridement, and parenteral administration of antibiotics. Meticulous care of the pin sites is essential to avoid this serious complication. Additionally, since all of the infections were associated with prolonged halo-skeletal traction, this technique should be used with caution and with an awareness of the possible increased risks of pin-site infection and of formation of a subdural abscess.

  14. Direct photoassociation of halo molecules in ultracold 86 Sr

    Science.gov (United States)

    Aman, J. A.; Hill, Joshua; Killian, T. C.

    2017-04-01

    We investigate the creation of 1S0 +1S0 halo molecules in strontium 86 through direct photoassociation in an optical dipole trap. We drive two photon Raman transitions near-resonance with a molecular level of the 1S0 +3P1 interatomic potential as the intermediate state. This provides large Frank-Condon factors and allows us to observe resonances for the creation of halo molecules through higher order Raman processes. The halo molecule is bound by EB 85 kHz at low excitation-laser intensity, but experiments show large AC Stark shifts of the molecular binding energy. These conditions suggest that STIRAP should be very effective for improving molecular conversion efficiency. Further experiments in a 3D lattice will explore molecular lifetimes and collision rates. Travel support provided by Shell Corporation.

  15. Axionic dark matter signatures in various halo models

    Energy Technology Data Exchange (ETDEWEB)

    Vergados, J.D., E-mail: vergados@uoi.gr [Center for Axion and Precision Physics Research, Institute for Basic Science (IBS), Daejeon 34141 (Korea, Republic of); Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141 (Korea, Republic of); ARC Centre of Excellence in Particle Physics at the Terascale and Centre for the Subatomic Structure of Matter (CSSM), University of Adelaide, Adelaide SA 5005 (Australia); Semertzidis, Y.K. [Center for Axion and Precision Physics Research, Institute for Basic Science (IBS), Daejeon 34141 (Korea, Republic of); Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141 (Korea, Republic of)

    2017-02-15

    In the present work we study possible signatures in the Axion Dark Matter searches. We focus on the dependence of the expected width in resonant cavities for various popular halo models, leading to standard velocity distributions, e.g. Maxwell–Boltzmann, as well as phase-mixed and non-virialized axionic dark matter (flows, caustic rings). We study, in particular, the time dependence of the resonance width (modulation) arising from such models. We find that the difference between the maximum (in June) and the minimum (in December) can vary by about 10% in the case of standard halos. In the case of mixed phase halos the variation is a bit bigger and for caustic rings the maximum is expected to occur a bit later. Experimentally such a modulation is observable with present technology.

  16. Particle ejection during mergers of dark matter halos

    Energy Technology Data Exchange (ETDEWEB)

    Carucci, Isabella P.; Sparre, Martin; Hansen, Steen H. [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, Copenhagen, 2100 Denmark (Denmark); Joyce, Michael, E-mail: carucci@dark-cosmology.dk, E-mail: sparre@dark-cosmology.dk, E-mail: hansen@dark-cosmology.dk, E-mail: joyce@lpnhe.in2p3.fr [Laboratoire de Physique Nucléaire et Hautes Énergies, Université Pierre et Marie Curie - Paris 6, CNRS IN2P3 UMR 7585, 4 Place Jussieu, Paris Cedex 05, 75752 France (France)

    2014-06-01

    Dark matter halos are built from accretion and merging. During merging some of the dark matter particles may be ejected with velocities higher than the escape velocity. We use both N-body simulations and single-particle smooth-field simulations to demonstrate that rapid changes to the mean field potential are responsible for such ejection, and in particular that dynamical friction plays no significant role in it. Studying a range of minor mergers, we find that typically between 5–15% of the particles from the smaller of the two merging structures are ejected. We also find that the ejected particles originate essentially from the small halo, and more specifically are particles in the small halo which pass later through the region in which the merging occurs.

  17. Simulation Studies of the Helium and Lead Observatory (HALO)

    Science.gov (United States)

    Sanford, Nikki; Scholberg, Kate

    2012-10-01

    Simulation studies for were conducted for the Helium and Lead Observatory (HALO), the supernova neutrino detector at SNOLAB, Sudbury, Ontario. HALO consists of 79 tons of lead, with 128 ^3He counters which detect the scattered lead neutrons resulting from incoming neutrinos. Improvements were made to the Geant4 Monte Carlo simulation's geometry by the addition of water boxes and plastic baseboards, which serve to reflect scattered neutrons back towards counters, and shield against outside neutrons and gammas. Several box designs were created, and the resulting event detection efficiencies and labeling of 1n and 2n events were studied. It was found that these additions cause a 2% efficiency increase, a slight improvement of correctly labeled events, and are a significant improvement to the HALO simulation.

  18. Reactions of Proton Halo Nuclei in a Relativistic Optical Potential

    CERN Document Server

    Rashdan, M

    2003-01-01

    The reaction cross section, sigma sub R; of the proton halo nuclei sup 1 sup 7 Ne and sup 1 sup 2 N on Si is calculated using an optical potential derived from the solution of the Dirac-Brueckner-Bethe-Goldstone equation, starting from the one-boson-exchange potential of Bonn. The nuclear densities are generated from self-consistent Hartree-Fock calculations using the recent Skyrme interaction SKRA. It is found that the enhancement in the reaction cross section found experimentally for the sup 1 sup 7 Ne + Si system in comparison to sup 1 sup 5 O + Si, where sup 1 sup 5 O has been considered as a core of sup 1 sup 7 Ne, is mainly due to the proton halo structure of sup 1 sup 7 Ne which increases the interaction, in the surface and tail regions. Glauber model calculations did not produce this enhancement in sigma sub R for proton halo nuclei

  19. Three-body halo nuclei in an effective theory framework

    Energy Technology Data Exchange (ETDEWEB)

    Canham, David L.

    2009-05-20

    The universal properties and structure of halo nuclei composed of two neutrons (2n) and a core are investigated within an effective quantum mechanics framework. We construct an effective interaction potential that exploits the separation of scales in halo nuclei and treat the nucleus as an effective three-body system, which to leading order is described by the large S-wave scattering lengths in the underlying two-body subsystems. The uncertainty from higher orders in the expansion is quantified through theoretical error bands. First, we investigate the possibility to observe excited Efimov states in 2n halo nuclei. Based on the experimental data, {sup 20}C is the only halo nucleus candidate to possibly have an Efimov excited state, with an energy less than 7 keV below the scattering threshold. Second, we study the structure of {sup 20}C and other 2n halo nuclei. In particular, we calculate their matter density form factors, radii, and two-neutron opening angles. We then make a systematic improvement upon these calculations by extending the effective potential to the next-to-leading order. To this order, we require an additional two-body parameter, which we tune to the effective range of the interaction. In addition to range corrections to the 2n halo nuclei results, we show corrections to the Efimov effect in the three-boson system. Furthermore, we explore universality in the linear range corrections to the Efimov spectrum. Finally, we study the scattering of D{sup 0} and D{sup *0} mesons and their antiparticles off the X(3872) in an effective field theory for short-range interactions. We present results for the S-wave scattering amplitude, total interaction cross section and S-wave scattering length. (orig.)

  20. Capacity of straylight and disk halo size to diagnose cataract.

    Science.gov (United States)

    Palomo-Álvarez, Catalina; Puell, María C

    2015-10-01

    To examine the capacity of straylight and disk halo size to diagnose cataract. Faculty of Optics and Optometry, Universidad Complutense de Madrid, Spain. Prospective study. Straylight, disk halo radius, and high-contrast corrected distance visual acuity (CDVA) measurements were compared between patients with age-related cataract and age-matched normal-sighted control subjects by calculating the area under the curve (AUC) receiver operating characteristic. Measurements were made in 53 eyes of 53 patients with a mean age of 67.94 years ± 7.11 (SD) and 31 eyes of 31 controls with a mean age 66.06 ± 5.43 years. Significantly worse (P cataract group than in the control group (1.17 ± 0.11 log[s], 2.10 ± 0.16 log arcmin, and 0.08 ± 0.08 logMAR). Significant differences in AUCs were observed for disk halo radius (0.89 ± 0.04) versus straylight (0.77 ± 0.05) (P = .03) and disk halo radius versus CDVA (0.72 ± 0.05) (P = .001). The comparison of disk halo radius versus the discriminant function with input from CDVA and straylight (0.80 ± 0.05) was at the limit of significance only (0.091 ± 0.05, P = .051). Although all 3 variables discriminated well between normal eyes and eyes with cataract, the disk halo radius showed the best diagnostic capacity. Neither author has a financial or proprietary interest in any material or method mentioned. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  1. The orbital eccentricity distribution of solar-neighbourhood halo stars

    Science.gov (United States)

    Hattori, K.; Yoshii, Y.

    2011-12-01

    We present theoretical calculations for the differential distribution of stellar orbital eccentricity for a sample of solar-neighbourhood halo stars. Two types of static, spherical gravitational potentials are adopted to define the eccentricity e for given energy E and angular momentum L, such as an isochrone potential and a Navarro-Frenk-White potential that can serve as two extreme ends covering in between any realistic potential of the Milky Way halo. The solar-neighbourhood eccentricity distribution ΔN(e) is then formulated, based on a static distribution function of the form f(E, L) in which the velocity anisotropy parameter β monotonically increases in the radial direction away from the galaxy centre, such that β is below unity (near-isotropic velocity dispersion) in the central region and asymptotically approaches ˜1 (radially anisotropic velocity dispersion) in the far distant region of the halo. We find that ΔN(e) sensitively depends upon the radial profile of β, and this sensitivity is used to constrain such a profile in comparison with some observational properties of ΔNobs(e) recently reported by Carollo et al. In particular, the linear e-distribution and the fraction of higher e stars for their sample of solar-neighbourhood inner-halo stars rule out a constant profile of β, contrary to the opposite claim by Bond et al. Our constraint of β≲ 0.5 at the galaxy centre indicates that the violent relaxation that has acted on the inner halo is effective within a scale radius of ˜10 kpc from the galaxy centre. We argue that our result would help to understand the formation and evolution of the Milky Way halo.

  2. The Halo Boundary of Galaxy Clusters in the SDSS

    Energy Technology Data Exchange (ETDEWEB)

    Baxter, Eric; Jain, Bhuvnesh; Sheth, Ravi K. [Center for Particle Cosmology, Department of Physics, University of Pennsylvania, Philadelphia, PA 19104 (United States); Chang, Chihway; Kravtsov, Andrey [Kavli Institute for Cosmological Physics, The University of Chicago, Chicago, IL 60637 (United States); Adhikari, Susmita; Dalal, Neal [Department of Astronomy, University of Illinois at Urbana-Champaign, Champaign, IL 61801 (United States); More, Surhud [Kavli Institute for the Physics and Mathematics of the Universe (WPI), Tokyo Institutes for Advanced Study, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa-shi, Chiba, 277-8583 (Japan); Rozo, Eduardo [Department of Physics, University of Arizona, Tucson, AZ 85721 (United States); Rykoff, Eli, E-mail: ebax@sas.upenn.edu [Kavli Institute for Particle Astrophysics and Cosmology, P.O. Box 2450, Stanford University, Stanford, CA 94305 (United States)

    2017-05-20

    Analytical models and simulations predict a rapid decline in the halo density profile associated with the transition from the “infalling” regime outside the halo to the “collapsed” regime within the halo. Using data from SDSS, we explore evidence for such a feature in the density profiles of galaxy clusters using several different approaches. We first estimate the steepening of the outer galaxy density profile around clusters, finding evidence for truncation of the halo profile. Next, we measure the galaxy density profile around clusters using two sets of galaxies selected on color. We find evidence of an abrupt change in galaxy colors that coincides with the location of the steepening of the density profile. Since galaxies that have completed orbits within the cluster are more likely to be quenched of star formation and thus appear redder, this abrupt change in galaxy color can be associated with the transition from single-stream to multi-stream regimes. We also use a standard model comparison approach to measure evidence for a “splashback”-like feature, but find that this approach is very sensitive to modeling assumptions. Finally, we perform measurements using an independent cluster catalog to test for potential systematic errors associated with cluster selection. We identify several avenues for future work: improved understanding of the small-scale galaxy profile, lensing measurements, identification of proxies for the halo accretion rate, and other tests. With upcoming data from the DES, KiDS, and HSC surveys, we can expect significant improvements in the study of halo boundaries.

  3. Signatures of compact halos of sterile-neutrino dark matter

    Science.gov (United States)

    Kühnel, Florian; Ohlsson, Tommy

    2017-11-01

    We investigate compact halos of sterile-neutrino dark matter and examine observable signatures with respect to neutrino and photon emission. Primarily, we consider two cases: primordial black-hole halos and ultracompact minihalos. In both cases, we find that there exists a broad range of possible parameter choices such that detection in the near future with x-ray and gamma-ray telescopes might be well possible. In fact, for energies above 10 TeV, the neutrino telescope IceCube would be a splendid detection machine for such macroscopic dark-matter candidates.

  4. The FUSE Survey of 0 VI in the Galactic Halo

    Science.gov (United States)

    Sonneborn, George; Savage, B. D.; Wakker, B. P.; Sembach, K. R.; Jenkins, E. B.; Moos, H. W.; Shull, J. M.

    2003-01-01

    This paper summarizes the results of the Far-Ultraviolet Spectroscopic Explorer (FUSE) program to study 0 VI in the Milky Way halo. Spectra of 100 extragalactic objects and two distant halo stars are analyzed to obtain measures of O VI absorption along paths through the Milky Way thick disk/halo. Strong O VI absorption over the velocity range from -100 to 100 km/s reveals a widespread but highly irregular distribution of O VI, implying the existence of substantial amounts of hot gas with T approx. 3 x 10(exp 5) K in the Milky Way thick disk/halo. The overall distribution of O VI is not well described by a symmetrical plane-parallel layer of patchy O VI absorption. The simplest departure from such a model that provides a reasonable fit to the observations is a plane-parallel patchy absorbing layer with an average O VI mid-plane density of n(sub 0)(O VI) = 1.7 x 10(exp -2)/cu cm, a scale height of approx. 2.3 kpc, and a approx. 0.25 dex excess of O VI in the northern Galactic polar region. The distribution of O VI over the sky is poorly correlated with other tracers of gas in the halo, including low and intermediate velocity H I, Ha emission from the warm ionized gas at approx. l0(exp 4) K, and hot X-ray emitting gas at approx. l0(exp 6) K . The O VI has an average velocity dispersion, b approx. 60 km/s and standard deviation of 15 km/s. Thermal broadening alone cannot explain the large observed profile widths. A combination of models involving the radiative cooling of hot fountain gas, the cooling of supernova bubbles in the halo, and the turbulent mixing of warm and hot halo gases is required to explain the presence of O VI and other highly ionized atoms found in the halo. The preferential venting of hot gas from local bubbles and superbubbles into the northern Galactic polar region may explain the enhancement of O VI in the North.

  5. Two distinct halo populations in the solar neighborhood. IV

    DEFF Research Database (Denmark)

    Nissen, P. E.; Schuster, W. J.

    2012-01-01

    We investigate if there is a difference in the lithium abundances of stars belonging to two halo populations of F and G main-sequence stars previously found to differ in [alpha/Fe] for the metallicity range -1.4 ...-resolution spectra using MARCS model atmospheres. Furthermore, masses of the stars are determined from the logTeff - logg diagram by interpolating between Yonsei-Yale evolutionary tracks. There is no significant systematic difference in the lithium abundances of high- and low-alpha halo stars. For the large majority...

  6. Dynamical Constraints On The Galaxy-Halo Connection

    Science.gov (United States)

    Desmond, Harry

    2017-07-01

    Dark matter halos comprise the bulk of the universe's mass, yet must be probed by the luminous galaxies that form within them. A key goal of modern astrophysics, therefore, is to robustly relate the visible and dark mass, which to first order means relating the properties of galaxies and halos. This may be expected not only to improve our knowledge of galaxy formation, but also to enable high-precision cosmological tests using galaxies and hence maximise the utility of future galaxy surveys. As halos are inaccessible to observations - as galaxies are to N-body simulations - this relation requires an additional modelling step.The aim of this thesis is to develop and evaluate models of the galaxy-halo connection using observations of galaxy dynamics. In particular, I build empirical models based on the technique of halo abundance matching for five key dynamical scaling relations of galaxies - the Tully-Fisher, Faber-Jackson, mass-size and mass discrepancy-acceleration relations, and Fundamental Plane - which relate their baryon distributions and rotation or velocity dispersion profiles. I then develop a statistical scheme based on approximate Bayesian computation to compare the predicted and measured values of a number of summary statistics describing the relations' important features. This not only provides quantitative constraints on the free parameters of the models, but also allows absolute goodness-of-fit measures to be formulated. I find some features to be naturally accounted for by an abundance matching approach and others to impose new constraints on the galaxy-halo connection; the remainder are challenging to account for and may imply galaxy-halo correlations beyond the scope of basic abundance matching.Besides providing concrete statistical tests of specific galaxy formation theories, these results will be of use for guiding the inputs of empirical and semi-analytic galaxy formation models, which require galaxy-halo correlations to be imposed by hand. As

  7. Comparison of Intra-cluster and M87 Halo Orphan Globular Clusters in the Virgo Cluster

    Science.gov (United States)

    Louie, Tiffany Kaye; Tuan, Jin Zong; Martellini, Adhara; Guhathakurta, Puragra; Toloba, Elisa; Peng, Eric; Longobardi, Alessia; Lim, Sungsoon

    2018-01-01

    We present a study of “orphan” globular clusters (GCs) — GCs with no identifiable nearby host galaxy — discovered in NGVS, a 104 deg2 CFHT/MegaCam imaging survey. At the distance of the Virgo cluster, GCs are bright enough to make good spectroscopic targets and many are barely resolved in good ground-based seeing. Our orphan GC sample is derived from a subset of NGVS-selected GC candidates that were followed up with Keck/DEIMOS spectroscopy. While our primary spectroscopic targets were candidate GC satellites of Virgo dwarf elliptical and ultra-diffuse galaxies, many objects turned out to be non-satellites based on a radial velocity mismatch with the Virgo galaxy they are projected close to. Using a combination of spectral characteristics (e.g., absorption vs. emission), Gaussian mixture modeling of radial velocity and positions, and extreme deconvolution analysis of ugrizk photometry and image morphology, these non-satellites were classified into: (1) intra-cluster GCs (ICGCs) in the Virgo cluster, (2) GCs in the outer halo of M87, (3) foreground Milky Way stars, and (4) background galaxies. The statistical distinction between ICGCs and M87 halo GCs is based on velocity distributions (mean of 1100 vs. 1300 km/s and dispersions of 700 vs. 400 km/s, respectively) and radial distribution (diffuse vs. centrally concentrated, respectively). We used coaddition to increase the spectral SNR for the two classes of orphan GCs and measured the equivalent widths (EWs) of the Mg b and H-beta absorption lines. These EWs were compared to single stellar population models to obtain mean age and metallicity estimates. The ICGCs and M87 halo GCs have = –0.6+/–0.3 and –0.4+/–0.3 dex, respectively, and mean ages of >~ 5 and >~ 10 Gyr, respectively. This suggests the M87 halo GCs formed in relatively high-mass galaxies that avoided being tidally disrupted by M87 until they were close to the cluster center, while IGCCs formed in relatively low-mass galaxies that were

  8. Toward a Combined SAGE II-HALOE Aerosol Climatology: An Evaluation of HALOE Version 19 Stratospheric Aerosol Extinction Coefficient Observations

    Science.gov (United States)

    Thomason, L. W.

    2012-01-01

    Herein, the Halogen Occultation Experiment (HALOE) aerosol extinction coefficient data is evaluated in the low aerosol loading period after 1996 as the first necessary step in a process that will eventually allow the production of a combined HALOE/SAGE II (Stratospheric Aerosol and Gas Experiment) aerosol climatology of derived aerosol products including surface area density. Based on these analyses, it is demonstrated that HALOE's 3.46 microns is of good quality above 19 km and suitable for scientific applications above that altitude. However, it is increasingly suspect at lower altitudes and should not be used below 17 km under any circumstances after 1996. The 3.40 microns is biased by about 10% throughout the lower stratosphere due to the failure to clear NO2 but otherwise appears to be a high quality product down to 15 km. The 2.45 and 5.26 micron aerosol extinction coefficient measurements are clearly biased and should not be used for scientific applications after the most intense parts of the Pinatubo period. Many of the issues in the aerosol data appear to be related to either the failure to clear some interfering gas species or doing so poorly. For instance, it is clear that the 3.40micronaerosol extinction coefficient measurements can be improved through the inclusion of an NO2 correction and could, in fact, end up as the highest quality overall HALOE aerosol extinction coefficient measurement. It also appears that the 2.45 and 5.26 micron channels may be improved by updating the Upper Atmosphere Pilot Database which is used as a resource for the removal of gas species otherwise not available from direct HALOE measurements. Finally, a simple model to demonstrate the promise of mixed visible/infrared aerosol extinction coefficient ensembles for the retrieval of bulk aerosol properties demonstrates that a combined HALOE/SAGE II aerosol climatology is feasible and may represent a substantial improvement over independently derived data sets.

  9. HaloTag: a novel reporter gene for positron emission tomography

    OpenAIRE

    Hong, Hao; Benink, Hélène A.; Zhang, Yin; Yang, Yunan; Uyeda, H. Tetsuo; Engle, Jonathan W.; Severin, Gregory W.; McDougall, Mark G; Barnhart, Todd E.; Klaubert, Dieter H.; Nickles, Robert J; Fan, Frank; Cai, Weibo

    2011-01-01

    Among the many molecular imaging techniques, reporter gene imaging has been a dynamic area of research. The HaloTag protein is a modified haloalkane dehalogenase which was designed to covalently bind to synthetic ligands (i.e. the HaloTag ligands [HTL]). Covalent bond formation between the HaloTag protein and the chloroal-kane within the HTL occurs rapidly under physiological conditions, which is highly specific and essentially irreversible. Over the years, HaloTag technology has been investi...

  10. Resolution of vitiligo following excision of halo congenital melanocytic nevus: a rare case report.

    Science.gov (United States)

    Wang, Kai; Wang, Zhi; Huang, Weiqing

    2016-05-01

    Halo congenital melanocytic nevus (CMN) associated with vitiligo is rare, especially with regard to CMN excision. Only two reports of excision of halo CMN following repigmentation of vitiligo are found in the literature. We present a case of a girl with halo CMN and periorbital vitiligo. The halo CMN was excised and followed by spontaneous improvement of vitiligo. The result suggests excision of the inciting lesion may be a promising way to control vitiligo. © 2015 Wiley Periodicals, Inc.

  11. Diffusion of Ca and Mg in Calcite

    Energy Technology Data Exchange (ETDEWEB)

    Cygan, R.T.; Fisler, D.K.

    1999-02-10

    The self-diffusion of Ca and the tracer diffusion of Mg in calcite have been experimentally measured using isotopic tracers of {sup 25}Mg and {sup 44}Ca. Natural single crystals of calcite were coated with a thermally-sputtered oxide thin film and then annealed in a CO{sub 2} gas at one atmosphere total pressure and temperatures from 550 to 800 C. Diffusion coefficient values were derived from the depth profiles obtained by ion microprobe analysis. The resultant activation energies for Mg tracer diffusion and Ca self-diffusion are respectively: E{sub a}(Mg) = 284 {+-} 74 kJ/mol and E{sub a}(Ca) = 271 {+-} 80 kJ/mol. For the temperature ranges in these experiments, the diffusion of Mg is faster than Ca. The results are generally consistent in magnitude with divalent cation diffusion rates obtained in previous studies and provide a means of interpreting the thermal histories of carbonate minerals, the mechanism of dolomitization, and other diffusion-controlled processes. The results indicate that cation diffusion in calcite is relatively slow and cations are the rate-limiting diffusing species for the deformation of calcite and carbonate rocks. Application of the calcite-dolomite geothermometer to metamorphic assemblages will be constrained by cation diffusion and cooling rates. The direct measurement of Mg tracer diffusion in calcite indicates that dolomitization is unlikely to be accomplished by Mg diffusion in the solid state but by a recrystallization process.

  12. Expression, one-step purification, and immobilization of HaloTag(TM) fusion proteins on chloroalkane-functionalized magnetic beads.

    Science.gov (United States)

    Motejadded, Hassan; Kranz, Bertolt; Berensmeier, Sonja; Franzreb, Matthias; Altenbuchner, Josef

    2010-11-01

    The presented work introduces a novel method to immobilize enzymes either purified or directly out of a crude extract onto magnetic particles in the micrometer range. This method is based on the creation of a fusion protein consisting of the enzyme of choice and a mutant dehalogenase. The dehalogenase gene is commercially available from the company Promega under the name HaloTag(TM). When the fusion protein is contacted with magnetic beads having chemically synthesized, chloroalkane ligands on their surface, the dehalogenase and the ligand undergo a covalent coupling leading to stable and spatially defined immobilization. The principle was proved with a lipase fused to the HaloTag(TM) gene and magnetic poly(methyl)methacrylate beads as carriers. The solubility of the tagged lipase was strongly increased by fusion of the malE gene at the N-terminal end of the HaloTag(TM) lipase gene. This tripartite protein was purified on amylose resin and used for immobilization. About 13 µg protein could be immobilized per 1 mg of beads within a few minutes. Due to the defined binding site, no activity loss was observed in the course of the immobilization. The resulting enzyme carrier was tested with the same beads up to six times for lipase activity over a storage period of 36 days at 8 °C. No loss of activity was found during this time.

  13. De bepaling van halo-azijnzuren, chloriet en chloraat in drinkwater

    NARCIS (Netherlands)

    Peters RJB; van de Meer-Arp KKM; Versteegh JFM

    1990-01-01

    A method was developed to determine halo-acetic acids with a detection limit of 0.1 mug/L. Halo-acetic acids were determined in samples drinking water derived from surface- and bankfiltrated water however, not in drinking water derived from groundwater. Halo-acetic acids were found in chlorinated

  14. Describing one-and two-neutron halos in effective field theory

    Indian Academy of Sciences (India)

    2014-11-01

    Nov 1, 2014 ... Click here to view fulltext PDF ... In this paper, the recent work our group has undertaken on effective field theory (EFT) analyses of experimental data pertaining to one- and two-neutron halo nuclei is discussed. The cases of 19C and 8Li (one-neutron halos) and 22C (two-neutron halo) are considered.

  15. Prospects for detecting supersymmetric dark matter in the Galactic halo

    NARCIS (Netherlands)

    Springel, V.; White, S. D. M.; Frenk, C. S.; Navarro, J. F.; Jenkins, A.; Vogelsberger, M.; Wang, J.; Ludlow, A.; Helmi, A.

    2008-01-01

    Dark matter is the dominant form of matter in the Universe, but its nature is unknown. It is plausibly an elementary particle, perhaps the lightest supersymmetric partner of known particle species(1). In this case, annihilation of dark matter in the halo of the Milky Way should produce gamma-rays at

  16. The Galactic Halo in Mixed Dark Matter Cosmologies

    NARCIS (Netherlands)

    Anderhalden, D.; Diemand, J.; Bertone, G.; Macciò, A.V.; Schneider, A.

    2012-01-01

    A possible solution to the small scale problems of the cold dark matter (CDM) scenario is that the dark matter consists of two components, a cold and a warm one. We perform a set of high resolution simulations of the Milky Way halo varying the mass of the WDM particle (mWDM) and the cosmic dark

  17. The prolate shape of the galactic dark-matter halo

    NARCIS (Netherlands)

    Helmi, A; Spooner, NJC; Kudryavtsev,

    2005-01-01

    Knowledge of the distribution of dark-matter in our Galaxy plays a crucial role in the interpretation of dark-matter detection experiments. I will argue here that probably the best way of constraining the properties of the dark-matter halo is through astrophysical observations. These provide

  18. Redshift space bias and beta from the halo model

    OpenAIRE

    Seljak, Uros

    2000-01-01

    We analyze scale dependence of redshift space bias $b$ and $\\beta \\equiv \\Omega_m^{0.6}/b$ in the context of the halo model. We show that linear bias is a good approximation only on large scales, for $k

  19. Lithium abundances in high- and low-alpha halo stars

    DEFF Research Database (Denmark)

    Nissen, P. E.; Schuster, W. J.

    2012-01-01

    A previous study of F and G main-sequence stars in the solar neighborhood has revealed the existence of two distinct halo populations with a clear separation in [alpha /Fe] for the metallicity range -1.4 < [Fe/H] < -0.7. The kinematics of the stars and models of galaxy formation suggest that the ...

  20. On the shape of the Galactic dark matter halo

    NARCIS (Netherlands)

    Helmi, A

    2004-01-01

    The confined nature of the debris from the Sagittarius dwarf to a narrow trail on the sky has recently prompted the suggestion that the dark matter halo of our Galaxy should be nearly spherical (Ibata et al. 2001; Majewski et al. 2003). This would seem to be in strong contrast with predictions from

  1. Jet interactions with the hot halos of clusters and galaxies

    NARCIS (Netherlands)

    McNamara, B.R.; Bîrzan, L.; Rafferty, D.A.; Nulsen, P.E.J.; Carilli, C.; Wise, M.W.

    2008-01-01

    X-ray observations of cavities and shock fronts produced by jets streaming through hot halos have significantly advanced our understanding of the energetics and dynamics of extragalactic radio sources. Radio sources at the centers of clusters have dynamical ages between ten and several hundred

  2. A halo model for cosmological neutral hydrogen : abundances and clustering

    Science.gov (United States)

    Padmanabhan, Hamsa; Refregier, Alexandre; Amara, Adam

    2017-08-01

    We extend the results of previous analyses towards constraining the abundance and clustering of post-reionization (z ∼ 0-5) neutral hydrogen (H i) systems using a halo model framework. We work with a comprehensive H I data set including the small-scale clustering, column density and mass function of H I galaxies at low redshifts, intensity mapping measurements at intermediate redshifts and the ultraviolet/optical observations of Damped Lyman Alpha (DLA) systems at higher redshifts. We use a Markov Chain Monte Carlo (MCMC) approach to constrain the parameters of the best-fitting models, both for the H i-halo mass (HIHM) relation and the H I radial density profile. We find that a radial exponential profile results in a good fit to the low-redshift H I observations, including the clustering and the column density distribution. The form of the profile is also found to match the high-redshift DLA observations, when used in combination with a three-parameter HIHM relation and a redshift evolution in the H I concentration. The halo model predictions are in good agreement with the observed H I surface density profiles of low-redshift galaxies, and the general trends in the impact parameter and covering fraction observations of high-redshift DLAs. We provide convenient tables summarizing the best-fitting halo model predictions.

  3. The Disk Mass Project: breaking the disk-halo degeneracy

    NARCIS (Netherlands)

    Verheijen, Marc A. W.; Bershady, Matthew A.; Swaters, Rob A.; Andersen, David R.; Westfall, Kyle B.; DE JONG, R. S.

    2007-01-01

    Little is known about the content and distribution of dark matter in spiral galaxies. To break the degeneracy in galaxy rotation curve decompositions, which allows a wide range of dark matter halo density profiles, an independent measure of the mass surface density of stellar disks is needed. Here,

  4. Halo-like structures studied by atomic force microscopy

    DEFF Research Database (Denmark)

    Sørensen, Alexis Hammer; Kyhle, Anders; Hansen, L. Theil

    1997-01-01

    Nanometer-sized clusters of copper have been produced in a hollow cathode sputtering source and deposited on SiOx. Halo-like structures consisting of micrometer sized protrusions in the solicon oxide surface surrounded by thin rings of smaller particles are observed. The area in between seems...

  5. The influence of halo evolution on galaxy structure

    Science.gov (United States)

    White, Simon

    2015-03-01

    If Einstein-Newton gravity holds on galactic and larger scales, then current observations demonstrate that the stars and interstellar gas of a typical bright galaxy account for only a few percent of its total nonlinear mass. Dark matter makes up the rest and cannot be faint stars or any other baryonic form because it was already present and decoupled from the radiation plasma at z = 1000, long before any nonlinear object formed. The weak gravito-sonic waves so precisely measured by CMB observations are detected again at z = 4 as order unity fluctuations in intergalactic matter. These subsequently collapse to form today's galaxy/halo systems, whose mean mass profiles can be accurately determined through gravitational lensing. High-resolution simulations link the observed dark matter structures seen at all these epochs, demonstrating that they are consistent and providing detailed predictions for all aspects of halo structure and growth. Requiring consistency with the abundance and clustering of real galaxies strongly constrains the galaxy-halo relation, both today and at high redshift. This results in detailed predictions for galaxy assembly histories and for the gravitational arena in which galaxies live. Dark halos are not expected to be passive or symmetric but to have a rich and continually evolving structure which will drive evolution in the central galaxy over its full life, exciting warps, spiral patterns and tidal arms, thickening disks, producing rings, bars and bulges. Their growth is closely related to the provision of new gas for galaxy building.

  6. Large-scale assembly bias of dark matter halos

    Science.gov (United States)

    Lazeyras, Titouan; Musso, Marcello; Schmidt, Fabian

    2017-03-01

    We present precise measurements of the assembly bias of dark matter halos, i.e. the dependence of halo bias on other properties than the mass, using curved "separate universe" N-body simulations which effectively incorporate an infinite-wavelength matter overdensity into the background density. This method measures the LIMD (local-in-matter-density) bias parameters bn in the large-scale limit. We focus on the dependence of the first two Eulerian biases bE1 and bE2 on four halo properties: the concentration, spin, mass accretion rate, and ellipticity. We quantitatively compare our results with previous works in which assembly bias was measured on fairly small scales. Despite this difference, our findings are in good agreement with previous results. We also look at the joint dependence of bias on two halo properties in addition to the mass. Finally, using the excursion set peaks model, we attempt to shed new insights on how assembly bias arises in this analytical model.

  7. Halo formation from mismatched beam-beam interactions

    Energy Technology Data Exchange (ETDEWEB)

    Qiang, Ji

    2003-05-23

    In this paper, we report on the halo formation and emittance growth driven by a parametric resonance during mismatched beam-beam collisions. In the regime of the weak-strong beam-beam interaction, if two beams have the same machine tunes, on-axis head-on collisions between a mismatched strong beam and a weak beam will not cause the formation of halo. However, if the two beams collide with an initial offset, the beam-beam force from the mismatched strong beam can cause halo formation and emittance growth in the weak beam. Meanwhile, if two beams have different machine tunes, for opposite charged colliding beams, when the machine tune of the weak beam is smaller than that of strong beam, there is emittance growth in the weak beam. When the machine tune of the weak beam is larger than that of the strong beam, there is little emittance growth. In the regime of strong-strong beam-beam interaction, halo is formed in both beams even when the two beams collide head-on on the axis with equal machine tunes. This puts a strong requirement for a good beam match during the injection to colliders in order to avoid the emittance growth.

  8. Planetary Nebulae as kinematic and dynamical tracers of galaxy halos

    NARCIS (Netherlands)

    Coccato, Lodovico; Napolitano, Nicola; Arnaboldi, Magda; Cortesi, Arianna; Romanowsky, Aaron; Gerhard, Ortwin; Merrifield, Michael; Kuijken, Konrad; Freeman, Ken; Douglas, Nigel

    2015-01-01

    The kinematics and dynamical properties of galaxy halos are difficult to measure, given the faint stellar surface brightness that characterizes those regions. Gas-rich systems such as spiral galaxies can be probed using the radio emission of their gas component. Early type galaxies contain less gas,

  9. Uncovering the hidden iceberg structure of the Galactic halo

    Science.gov (United States)

    Moss, Vanessa A.; Di Teodoro, Enrico M.; McClure-Griffiths, Naomi M.; Lockman, Felix; Pisano, D. J.; Price, Daniel; Rees, Glen

    2018-01-01

    How the Milky Way gets its gas and keeps its measured star formation rate going are both long-standing mysteries in Galactic studies, with important implications for galaxy evolution across the Universe. I will present our recent discovery of two populations of neutral hydrogen (HI) in the halo of the Milky Way: 1) a narrow line-width dense population typical of the majority of bright high velocity cloud (HVC) components, and 2) a fainter, broad line-width diffuse population that aligns well with the population found in very sensitive pointings such as in Lockman et al. (2002). From our existing data, we concluded that the diffuse population likely outweighs the dense HI by a factor of 3. This discovery of diffuse HI, which appears to be prevalent throughout the halo, takes us closer to solving the Galactic mystery of accretion and reveals a gaseous neutral halo hidden from the view of most large-scale surveys. We are currently carrying out deep Parkes observations to investigate these results further, in order to truly uncover the nature of the diffuse HI and determine whether our 3:1 ratio (based on the limited existing data) is consistent with what is seen when Parkes and the 140 ft Green Bank telescope are employed at comparable sensitivity. With these data, through a combination of both known and new sightline measurements, we aim to reveal the structure of the Galactic halo in more detail than ever before.

  10. The reversed halo sign: update and differential diagnosis

    Science.gov (United States)

    Godoy, M C B; Viswanathan, C; Marchiori, E; Truong, M T; Benveniste, M F; Rossi, S; Marom, E M

    2012-01-01

    The reversed halo sign is characterised by a central ground-glass opacity surrounded by denser air–space consolidation in the shape of a crescent or a ring. It was first described on high-resolution CT as being specific for cryptogenic organising pneumonia. Since then, the reversed halo sign has been reported in association with a wide range of pulmonary diseases, including invasive pulmonary fungal infections, paracoccidioidomycosis, pneumocystis pneumonia, tuberculosis, community-acquired pneumonia, lymphomatoid granulomatosis, Wegener granulomatosis, lipoid pneumonia and sarcoidosis. It is also seen in pulmonary neoplasms and infarction, and following radiation therapy and radiofrequency ablation of pulmonary malignancies. In this article, we present the spectrum of neoplastic and non-neoplastic diseases that may show the reversed halo sign and offer helpful clues for assisting in the differential diagnosis. By integrating the patient's clinical history with the presence of the reversed halo sign and other accompanying radiological findings, the radiologist should be able to narrow the differential diagnosis substantially, and may be able to provide a presumptive final diagnosis, which may obviate the need for biopsy in selected cases, especially in the immunosuppressed population. PMID:22553298

  11. Alpha alpha scattering in halo effective field theory

    NARCIS (Netherlands)

    Higa, R.; Hammer, H. -W.; van Kolck, U.

    2008-01-01

    We study the two-alpha-particle (alpha alpha) system in an Effective Field Theory (EFT) for halo-like systems. We propose a power Counting that incorporates the subtle interplay of strong and electromagnetic forces leading to a narrow resonance at an energy of about 0.1 MeV. We investigate the EFT

  12. Matting of Hair Due to Halo-egg Shampoo

    Directory of Open Access Journals (Sweden)

    Z M Mani

    1983-01-01

    Full Text Available A case of hair matting in an 18 year old female is reported. The hair got densely entangled immediately after washing the hair with ′Halo Egg′ shampoo. The hair was disentangled completely after prolonged dipping of the hair in arachis oil frr 5 days.

  13. A galaxy-halo model for multiple cosmological tracers

    Science.gov (United States)

    Bull, Philip

    2017-10-01

    The information extracted from large galaxy surveys with the likes of DES, DESI, Euclid, LSST, SKA, and WFIRST will be greatly enhanced if the resultant galaxy catalogues can be cross-correlated with one another. Predicting the nature of the information gain, and developing the tools to realize it, depends on establishing a consistent model of how the galaxies detected by each survey trace the same underlying matter distribution. Existing analytic methods, such as halo occupation distribution modelling, are not well suited for this task, and can suffer from ambiguities and tuning issues when applied to multiple tracers. In this paper, we take the first step towards constructing an alternative that provides a common model for the connection between galaxies and dark matter haloes across a wide range of wavelengths (and thus tracer populations). This is based on a chain of parametrized statistical distributions that model the connection between (I) halo mass and bulk physical properties of galaxies, such as star formation rate; and (II) those same physical properties and a variety of emission processes. The result is a flexible parametric model that allows analytic halo model calculations of one-point functions to be carried out for multiple tracers, as well as providing semi realistic galaxy properties for fast mock catalogue generation.

  14. Giant Radio Halos in Galaxy Clusters as Probes of Particle ...

    Indian Academy of Sciences (India)

    Giant radio halos in galaxy clusters probe mechanisms of particle acceleration connected with cluster merger events. Shocks and turbulence are driven in the inter-galactic medium (IGM) during clusters mergers and may have a deep impact on the non-thermal properties of galaxy clusters. Models of turbulent ...

  15. Inheritance of halo blight resistance in common bean | Chataika ...

    African Journals Online (AJOL)

    Halo blight caused by (Pseudomonas syringe pv. phaseolicola (Burkh) (Psp)) is an important disease of common bean (Phaseolus vulgaris L.) world-wide. Several races of the Psp exist and likewise some sources of resistance in common bean have been identified. CAL 143, is a CIAT-bred common bean line, which was ...

  16. DM haloes in the fifth-force cosmology

    NARCIS (Netherlands)

    Hellwing, Wojciech A.; Cautun, Marius; Knebe, Alexander; Juszkiewicz, Roman; Knollmann, Steffen

    2013-01-01

    We investigate how long-range scalar interactions affect the properties of dark matter haloes. For doing so we employ the ReBEL model which implements an additional interaction between dark matter particles. On the phenomenological level this is equivalent to a modification of gravity. We analyse

  17. Prospects for detecting supersymmetric dark matter in the Galactic halo.

    Science.gov (United States)

    Springel, V; White, S D M; Frenk, C S; Navarro, J F; Jenkins, A; Vogelsberger, M; Wang, J; Ludlow, A; Helmi, A

    2008-11-06

    Dark matter is the dominant form of matter in the Universe, but its nature is unknown. It is plausibly an elementary particle, perhaps the lightest supersymmetric partner of known particle species. In this case, annihilation of dark matter in the halo of the Milky Way should produce gamma-rays at a level that may soon be observable. Previous work has argued that the annihilation signal will be dominated by emission from very small clumps (perhaps smaller even than the Earth), which would be most easily detected where they cluster together in the dark matter haloes of dwarf satellite galaxies. Here we report that such small-scale structure will, in fact, have a negligible impact on dark matter detectability. Rather, the dominant and probably most easily detectable signal will be produced by diffuse dark matter in the main halo of the Milky Way. If the main halo is strongly detected, then small dark matter clumps should also be visible, but may well contain no stars, thereby confirming a key prediction of the cold dark matter model.

  18. Is the halo responsible for the microlensing events?

    CERN Document Server

    Roulet, E.; Giudice, G.F.

    1994-01-01

    Abstract: We discuss whether the astrophysical objects responsible for the recently reported microlensing events of sources in the Large Magellanic Cloud can be identified as the brown dwarf components of the spheroid of our galaxy, rather than the constituents of a dark baryonic halo.

  19. Lensing effects of misaligned disks in dark matter halos

    NARCIS (Netherlands)

    Quadri, R.; Möller, O.; Natarajan, P.

    2002-01-01

    Published in: Astrophys. J. 597 (2003) 659-671 citations recorded in [Science Citation Index] Abstract: We study the observational signatures of the lensing signal produced by dark matter halos with embedded misaligned disks. This issue is of particular interest at the present time since most of the

  20. Spin alignment of dark matter haloes in filaments and walls

    NARCIS (Netherlands)

    Aragón-Calvo, M. A.; Weygaert, R. van de; Jones, B. J. T.; Hulst, T. van der

    2006-01-01

    Abstract: The MMF technique is used to segment the cosmic web as seen in a cosmological N-body simulation into wall-like and filament-like structures. We find that the spins and shapes of dark matter haloes are significantly correlated with each other and with the orientation of their host

  1. Spin alignment of dark matter halos in filaments and walls

    NARCIS (Netherlands)

    Aragon-Calvo, Miguel A.; van de Weygaert, Rien; Jones, Bernard J. T.; van der Hulst, J. M.

    2007-01-01

    The MMF technique is used to segment the cosmic web as seen in a cosmological N-body simulation into wall-like and filament-like structures. We find that the spins and shapes of dark matter halos are significantly correlated with each other and with the orientation of their host structures. The

  2. Fast weak-lensing simulations with halo model

    Science.gov (United States)

    Giocoli, Carlo; Di Meo, Sandra; Meneghetti, Massimo; Jullo, Eric; de la Torre, Sylvain; Moscardini, Lauro; Baldi, Marco; Mazzotta, Pasquale; Metcalf, R. Benton

    2017-09-01

    Full ray-tracing maps of gravitational lensing, constructed from N-body simulations, represent a fundamental tool to interpret present and future weak-lensing data. However, the limitation of computational resources and storage capabilities severely restricts the number of realizations that can be performed in order to accurately sample both the cosmic shear models and covariance matrices. In this paper, we present a halo model formalism for weak gravitational lensing that alleviates these issues by producing weak-lensing mocks at a reduced computational cost. Our model takes as input the halo population within a desired light cone and the linear power spectrum of the underlined cosmological model. We examine the contribution given by the presence of substructures within haloes to the cosmic shear power spectrum and quantify it to the percent level. Our method allows us to reconstruct high-resolution convergence maps, for any desired source redshifts, of light cones that realistically trace the matter density distribution in the universe, account for masked area and sample selections. We compare our analysis on the same large-scale structures constructed using ray-tracing techniques and find very good agreements in both the linear and non-linear regimes up to few percent levels. The accuracy and speed of our method demonstrate the potential of our halo model for weak-lensing statistics and the possibility to generate a large sample of convergence maps for different cosmological models as needed for the analysis of large galaxy redshift surveys.

  3. Giant Radio Halos in Galaxy Clusters as Probes of Particle ...

    Indian Academy of Sciences (India)

    Abstract. Giant radio halos in galaxy clusters probe mechanisms of particle acceleration connected with cluster merger events. Shocks and turbulence are driven in the inter-galactic medium (IGM) during clusters mergers and may have a deep impact on the non-thermal properties of galaxy clusters. Models of turbulent ...

  4. Cosmic Rays in the Disk and Halo of Galaxies

    Science.gov (United States)

    Dogiel, V. A.; Breitschwerdt, D.

    2012-09-01

    We give a review of cosmic ray propagation models. It is shown that the development of the theory of cosmic ray origin leads inevitably to the conclusion that cosmic ray propagation in the Galaxy is determined by effective particle scattering, which is described by spatial diffusion. The Galactic Disk is surrounded by an extended halo, in which cosmic rays are confined before escaping into intergalactic space. For a long time cosmic ray convective outflow from the Galaxy (galactic wind) was believed to be insignificant. However, investigations of hydrodynamic stability and an analysis of ISM dynamics (including cosmic rays) showed that a galactic wind was emanating near the disk, and accelerating towards the halo, reaching its maximum velocity far away from the disk. Therefore convective cosmic ray transport should be important in galactic halos. Recent analysis of the gamma-ray emissivity in the Galactic disk of EGRET data, which showed that cosmic rays are more or less uniformly distributed in the radial direction of the disk, as well as the interpretation of soft X-ray emission in galactic halos, give convincing evidence of the existence of a galactic wind in star forming galaxies.

  5. "Safe" Coulomb Excitation of $^{30}$Mg

    CERN Document Server

    Niedermaier, O; Bildstein, V; Boie, H; Fitting, J; Von Hahn, R; Köck, F; Lauer, M; Pal, U K; Podlech, H; Repnow, R; Schwalm, D; Alvarez, C; Ames, F; Bollen, G; Emhofer, S; Habs, D; Kester, O; Lutter, R; Rudolph, K; Pasini, M; Thirolf, P G; Wolf, B H; Eberth, J; Gersch, G; Hess, H; Reiter, P; Thelen, O; Warr, N; Weisshaar, D; Aksouh, F; Van den Bergh, P; Van Duppen, P; Huyse, M; Ivanov, O; Mayet, P; Van de Walle, J; Äystö, J; Butler, P A; Cederkäll, J; Delahaye, P; Fynbo, H O U; Fraile-Prieto, L M; Forstner, O; Franchoo, S; Köster, U; Nilsson, T; Oinonen, M; Sieber, T; Wenander, F; Pantea, M; Richter, A; Schrieder, G; Simon, H; Behrens, T; Gernhäuser, R; Kröll, T; Krücken, R; Münch, M M; Davinson, T; Gerl, J; Huber, G; Hurst, A; Iwanicki, J; Jonson, B; Lieb, P; Liljeby, L; Schempp, A; Scherillo, A; Schmidt, P; Walter, G

    2005-01-01

    We report on the first radioactive beam experiment performed at the recently commissioned REX-ISOLDE facility at CERN in conjunction with the highly efficient $\\gamma$ -spectrometer MINIBALL. Using $^{30}$Mg ions accelerated to an energy of 2.25MeV/u together with a thin $^{nat}$Ni target, Coulomb excitation of the first excited 2+ states of the projectile and target nuclei well below the Coulomb barrier was observed. From the measured relative de-excitation $\\gamma$ -ray yields the B(E2; 0$^{+}_{gs} \\rightarrow 2^{+}_{1}$) value of $^{30}$Mg was determined to be 241(31)$e^{2}$fm$^{4}$. Our result is lower than values obtained at projectile fragmenttion facilities using the intermediate-energy Coulomb excitation method and confirms that the theoretical conjecture that the neutron-rich magnesium isotope $^{30}$Mg lies still outside the "island of inversion".

  6. The halo sign: HRCT findings in 85 patients.

    Science.gov (United States)

    Alves, Giordano Rafael Tronco; Marchiori, Edson; Irion, Klaus; Nin, Carlos Schuler; Watte, Guilherme; Pasqualotto, Alessandro Comarú; Severo, Luiz Carlos; Hochhegger, Bruno

    2016-01-01

    The halo sign consists of an area of ground-glass opacity surrounding pulmonary lesions on chest CT scans. We compared immunocompetent and immunosuppressed patients in terms of halo sign features and sought to identify those of greatest diagnostic value. This was a retrospective study of CT scans performed at any of seven centers between January of 2011 and May of 2015. Patients were classified according to their immune status. Two thoracic radiologists reviewed the scans in order to determine the number of lesions, as well as their distribution, size, and contour, together with halo thickness and any other associated findings. Of the 85 patients evaluated, 53 were immunocompetent and 32 were immunosuppressed. Of the 53 immunocompetent patients, 34 (64%) were diagnosed with primary neoplasm. Of the 32 immunosuppressed patients, 25 (78%) were diagnosed with aspergillosis. Multiple and randomly distributed lesions were more common in the immunosuppressed patients than in the immunocompetent patients (p Pacientes imunocompetentes e imunodeprimidos foram comparados quanto a características do sinal do halo a fim de identificar as de maior valor diagnóstico. Estudo retrospectivo de tomografias realizadas em sete centros entre janeiro de 2011 e maio de 2015. Os pacientes foram classificados de acordo com seu estado imunológico. Dois radiologistas torácicos analisaram os exames a fim de determinar o número de lesões e sua distribuição, tamanho e contorno, bem como a espessura do halo e quaisquer outros achados associados. Dos 85 pacientes avaliados, 53 eram imunocompetentes e 32 eram imunodeprimidos. Dos 53 pacientes imunocompetentes, 34 (64%) receberam diagnóstico de neoplasia primária. Dos 32 pacientes imunodeprimidos, 25 (78%) receberam diagnóstico de aspergilose. Lesões múltiplas e distribuídas aleatoriamente foram mais comuns nos imunodeprimidos do que nos imunocompetentes (p pacientes imunocompetentes são bastante diferentes das observadas em

  7. Efficient protein knockdown of HaloTag-fused proteins using hybrid molecules consisting of IAP antagonist and HaloTag ligand.

    Science.gov (United States)

    Tomoshige, Shusuke; Hashimoto, Yuichi; Ishikawa, Minoru

    2016-07-15

    We previously reported a protein knockdown system for HaloTag-fused proteins using hybrid small molecules consisting of alkyl chloride, which binds covalently to HaloTag, linked to BE04 (2), a bestatin (3) derivative with an affinity for cellular inhibitor of apoptosis protein 1 (cIAP1, a kind of ubiquitin ligase). This system addressed several limitations of prior protein knockdown technology, and was applied to degrade two HaloTag-fused proteins. However, the degradation activity of these hybrid small molecules was not potent. Therefore, we set out to improve this system. We report here the design, synthesis and biological evaluation of novel hybrid compounds 4a and 4b consisting of alkyl chloride linked to IAP antagonist MV1 (5). Compounds 4a and 4b were confirmed to reduce the levels of HaloTag-fused tumor necrosis factor α (HaloTag-TNFα), HaloTag-fused cell division control protein 42 (HaloTag-Cdc42), and unfused HaloTag protein in living cells more potently than did BE04-linked compound 1b. Analysis of the mode of action revealed that the reduction of HaloTag-TNFα is proteasome-dependent, and is also dependent on the linker structure between MV1 (5) and alkyl chloride. These compounds appear to induce ubiquitination at the HaloTag moiety of HaloTag-fused proteins. Our results indicate that these newly synthesized MV1-type hybrid compounds, 4a and 4b, are efficient tools for protein knockdown for HaloTag-fused proteins. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Nuclear Charge Radii of $^{7,9,10}Be$ and the one-neutron halo nucleus $^{11}Be

    CERN Document Server

    Nörtershäuser, W; Záková, M; Andjelkovic, Z; Blaum, K; Bissell, M L; Cazan, R; Drake, G W F; Geppert, Ch; Kowalska, M; Krämer, J; Krieger, A; Neugart, R; Sánchez, R; Schmidt-Kaler, F; Yan, Z C; Yordanov, D T; Zimmermann, C

    2009-01-01

    The nuclear charge radii of $^{7,9,10,11}$Be have been determined by high-precision laser spectroscopy. On-line measurements were performed at ISOLDE with collinear laser spectroscopy in the $2s_{1/2} \\to 2p_{1/2}$ transition of Be$^{+}$. Simultaneous measurements in collinear and anti-collinear direction combined with absolute frequency determination using a frequency comb yielded accuracy in the isotope shift measurements of better than 1 MHz. Combined with accurate calculations of the mass-dependent isotope shifts the nuclear charge radii along the isotopic chain were extracted. The charge radius decreases from $^7$Be to $^{10}$Be and then increases for the halo nucleus $^{11}$Be. When comparing our results with predictions of {\\it ab-initio} nuclear structure calculations we find good agreement. Additionally, the nuclear magnetic moment of $^7$Be was determined to be 1.3998(15) $\\mu_{\\rm N}$ and that of $^{11}$Be was confirmed with an accuracy similar to previous $\\beta$-NMR measurements.

  9. Constraints on the Formation of M31’s Stellar Halo from the SPLASH Survey

    Directory of Open Access Journals (Sweden)

    Karoline Gilbert

    2017-09-01

    Full Text Available The SPLASH (Spectroscopic and Photometric Landscape of Andromeda’s Stellar Halo Survey has observed fields throughout M31’s stellar halo, dwarf satellites, and stellar disk. The observations and derived measurements have either been compared to predictions from simulations of stellar halo formation or modeled directly in order to derive inferences about the formation and evolution of M31’s stellar halo. We summarize some of the major results from the SPLASH survey and the resulting implications for our understanding of the build-up of M31’s stellar halo.

  10. A Phenomenological Model of Star Formation Efficiency in Dark Matter Halos

    Science.gov (United States)

    Finnegan, Daniel; Alsheshakly, Ghadeer; Moustakas, John

    2018-01-01

    The efficiency of star formation in massive dark matter halos is extraordinarily low, less than 10% in >10^13 Msun sized halos. Although many physical processes have been proposed to explain this low efficiency, such as feedback from supermassive black halos and massive stars, this question remains one of the most important outstanding problems in galaxy evolution. To explore this problem, we build a simple phenomenological model to predict the variations in gas fraction and star formation efficiency as a function of halo mass. We compare our model predictions to central galaxy stellar masses and halo masses drawn from the literature, and discuss plans for our future work.

  11. ZOMG - III. The effect of halo assembly on the satellite population

    Science.gov (United States)

    Garaldi, Enrico; Romano-Díaz, Emilio; Borzyszkowski, Mikolaj; Porciani, Cristiano

    2018-01-01

    We use zoom hydrodynamical simulations to investigate the properties of satellites within galaxy-sized dark-matter haloes with different assembly histories. We consider two classes of haloes at redshift z = 0: 'stalled' haloes that assembled at z > 1 and 'accreting' ones that are still forming nowadays. Previously, we showed that the stalled haloes are embedded within thick filaments of the cosmic web, while the accreting ones lie where multiple thin filaments converge. We find that satellites in the two classes have both similar and different properties. Their mass spectra, radial count profiles, baryonic and stellar content, and the amount of material they shed are indistinguishable. However, the mass fraction locked in satellites is substantially larger for the accreting haloes as they experience more mergers at late times. The largest difference is found in the satellite kinematics. Substructures fall towards the accreting haloes along quasi-radial trajectories whereas an important tangential velocity component is developed, before accretion, while orbiting the filament that surrounds the stalled haloes. Thus, the velocity anisotropy parameter of the satellites (β) is positive for the accreting haloes and negative for the stalled ones. This signature enables us to tentatively categorize the Milky Way halo as stalled based on a recent measurement of β. Half of our haloes contain clusters of satellites with aligned orbital angular momenta corresponding to flattened structures in space. These features are not driven by baryonic physics and are only found in haloes hosting grand-design spiral galaxies, independently of their assembly history.

  12. Detection of Hot Halo Gets Theory Out of Hot Water

    Science.gov (United States)

    2006-02-01

    Scientists using NASA's Chandra X-ray Observatory have detected an extensive halo of hot gas around a quiescent spiral galaxy. This discovery is evidence that galaxies like our Milky Way are still accumulating matter from the gradual inflow of intergalactic gas. "What we are likely witnessing here is the ongoing galaxy formation process," said Kristian Pedersen of the University of Copenhagen, Denmark, and lead author of a report on the discovery. Chandra observations show that the hot halo extends more than 60,000 light years on either side of the disk of the galaxy known as NGC 5746. The detection of such a large halo alleviates a long-standing problem for the theory of galaxy formation. Spiral galaxies are thought to form from enormous clouds of intergalactic gas that collapse to form giant, spinning disks of stars and gas. Chandra X-ray Image of NGC 5746 Chandra X-ray Image of NGC 5746 One prediction of this theory is that large spiral galaxies should be immersed in halos of hot gas left over from the galaxy formation process. Hot gas has been detected around spiral galaxies in which vigorous star formation is ejecting matter from the galaxy, but until now hot halos due to infall of intergalactic matter have not been detected. "Our observations solve the mystery of the missing hot halos around spiral galaxies," said Pedersen. "The halos exist, but are so faint that an extremely sensitive telescope such as Chandra is needed to detect them." DSS Optical Image of NGC 5746 DSS Optical Image of NGC 5746 NGC 5746 is a massive spiral galaxy about a 100 million light years from Earth. Its disk of stars and gas is viewed almost edge-on. The galaxy shows no signs of unusual star formation, or energetic activity from its nuclear region, making it unlikely that the hot halo is produced by gas flowing out of the galaxy. "We targeted NGC 5746 because we thought its distance and orientation would give us the best chance to detect a hot halo caused by the infall of

  13. Halo histories versus Galaxy properties at z = 0 - I. The quenching of star formation

    Science.gov (United States)

    Tinker, Jeremy L.; Wetzel, Andrew R.; Conroy, Charlie; Mao, Yao-Yuan

    2017-12-01

    We test whether halo age and galaxy age are correlated at fixed halo and galaxy mass. The formation histories, and thus ages, of dark matter haloes correlate with their large-scale density ρ, an effect known as assembly bias. We test whether this correlation extends to galaxies by measuring the dependence of galaxy stellar age on ρ. To clarify the comparison between theory and observation, and to remove the strong environmental effects on satellites, we use galaxy group catalogues to identify central galaxies and measure their quenched fraction, fQ, as a function of large-scale environment. Models that match halo age to central galaxy age predict a strong positive correlation between fQ and ρ. However, we show that the amplitude of this effect depends on the definition of halo age: assembly bias is significantly reduced when removing the effects of splashback haloes - those haloes that are central but have passed through a larger halo or experienced strong tidal encounters. Defining age using halo mass at its peak value rather than current mass removes these effects. In Sloan Digital Sky Survey data, at M* ≳ 1010 M⊙ h-2, there is a ∼5 per cent increase in fQ from low-to-high densities, which is in agreement with predictions of dark matter haloes using peak halo mass. At lower stellar mass there is little to no correlation of fQ with ρ. For these galaxies, age matching is inconsistent with the data across the range of halo formation metrics that we tested. This implies that halo formation history has a small but statistically significant impact on quenching of star formation at high masses, while the quenching process in low-mass central galaxies is uncorrelated with halo formation history.

  14. Moving-mesh cosmology: characteristics of galaxies and haloes

    Science.gov (United States)

    Kereš, Dušan; Vogelsberger, Mark; Sijacki, Debora; Springel, Volker; Hernquist, Lars

    2012-09-01

    We discuss cosmological hydrodynamic simulations of galaxy formation performed with the new moving-mesh code AREPO, which promises higher accuracy compared with the traditional smoothed particle hydrodynamics (SPH) technique that has been widely employed for this problem. In this exploratory study, we deliberately limit the complexity of the physical processes followed by the code for ease of comparison with previous calculations, and include only cooling of gas with a primordial composition, heating by a spatially uniform ultraviolet background, and a simple subresolution model for regulating star formation in the dense interstellar medium. We use an identical set of physics in corresponding simulations carried out with the well-tested SPH code GADGET, adopting also the same high-resolution gravity solver. We are thus able to compare both simulation sets on an object-by-object basis, allowing us to cleanly isolate the impact of different hydrodynamical methods on galaxy and halo properties. In accompanying papers, Vogelsberger et al. and Sijacki et al., we focus on an analysis of the global baryonic statistics predicted by the simulation codes, and complementary idealized simulations that highlight the differences between the hydrodynamical schemes. Here we investigate their influence on the baryonic properties of simulated galaxies and their surrounding haloes. We find that AREPO leads to significantly higher star formation rates for galaxies in massive haloes and to more extended gaseous discs in galaxies, which also feature a thinner and smoother morphology than their GADGET counterparts. Consequently, galaxies formed in AREPO have larger sizes and higher specific angular momentum than their SPH correspondents. Interestingly, the more efficient cooling flows in AREPO yield higher densities and lower entropies in halo centres compared to GADGET, whereas the opposite trend is found in halo outskirts. The cooling differences leading to higher star formation rates

  15. Contribution of stable isotopes to the study of pharmacokinetics of magnesium salts; Apport des isotopes stables a l'etude de la pharmacocinetique de sels de magnesium

    Energy Technology Data Exchange (ETDEWEB)

    Benech, H

    1999-05-28

    The use of stable isotopes as labels is becoming an attractive tool for the study of magnesium behavior in humans. It has been used two stable isotopes of magnesium, {sup 25}Mg and {sup 26}Mg, to measure the absolute bioavailability of a pharmaceutical form of magnesium. (N.C.)

  16. Proton halos in the 1 s0 d shell

    Science.gov (United States)

    Brown, B. A.; Hansen, P. G.

    1996-02-01

    The shell-model properties of proton halo states in proton-rich 1 s0 d shell nuclei are investigated. The most interesting cases appear to be those in 26,27P and 27S. The parallel-momentum distributions of core fragments from proton stripping reactions may provide experimental insight into the structure of the halo states and the role played by the reaction mechanism. The “generalized Coulomb shift”, defined as the difference between the neutron and proton separation energies for an analogue pair, is shown to vary smoothly as a function of proton-separation energy and provides a good tool for mass extrapolations. The relation between the total interaction cross section and the matter radius is discussed.

  17. Galactic Halo Wormhole Solutions in f(T Gravity

    Directory of Open Access Journals (Sweden)

    M. Sharif

    2014-01-01

    Full Text Available The proposal of galactic halo region is based on the idea that dark halos contain some characteristics needed to support traversable wormhole solutions. We explore wormhole solutions in this region in the framework of generalized teleparallel gravity. We consider static spherically symmetric wormhole spacetime with flat galactic rotational curves and obtain expressions of matter components for nondiagonal tetrad. The effective energy-momentum tensor leads to the violation of energy conditions which may impose condition on the normal matter to satisfy these conditions. We take two well-known f(T models in exponential and logarithmic forms to discuss wormhole solutions as well as the equilibrium condition. It is concluded that wormhole solutions violating weak energy condition are obtained for both models with stable configuration.

  18. Two distinct halo populations in the solar neighborhood. III

    DEFF Research Database (Denmark)

    Schuster, W. J.; Moreno, E.; Nissen, Poul Erik

    2012-01-01

    Context. In Papers I and II of this series, we have found clear indications of the existence of two distinct populations of stars in the solar neighborhood belonging to the metal-rich end of the halo metallicity distribution function. Based on high-resolution, high S/N spectra, it is possible...... to distinguish between “high-alpha” and “low-alpha” components using the [α/Fe] versus [Fe/H] diagram. Aims. Precise relative ages and orbital parameters are determined for 67 halo and 16 thick-disk stars having metallicities in the range −1.4 ... populations in the formation and evolution of the Galaxy. Methods. Ages are derived by comparing the positions of stars in the log Teff–log g diagram with isochrones from the Y2 models interpolated to the exact [Fe/H] and [α/Fe] values of each star. The stellar parameters have been adopted from the preceding...

  19. The abundance of boron in three halo stars

    Science.gov (United States)

    Duncan, Douglas K.; Lambert, David L.; Lemke, Michael

    1992-01-01

    B abundances for three halo stars: HD 140283, HD 19445, and HD 201891 are presented. Using recent determinations of the Be abundance in HD 140283, B/Be of 10 +5/-4 is found for this star, and similar ratios are inferred for HD 19445 and HD 201891. This ratio is equal to the minimum value of 10 expected from a synthesis of B and Be by high-energy cosmic-ray spallation reactions in the interstellar medium. It is shown that the accompanying synthesis of Li by alpha on alpha fusion reactions is probably a minor contributor to the observed 'primordial' Li of halo stars. The observed constant ratios of B/O and Be/O are expected if the principal channel of synthesis involves cosmic-ray CNO nuclei from the supernovae colliding with interstellar protons.

  20. Toward a combined SAGE II-HALOE aerosol climatology: an evaluation of HALOE version 19 stratospheric aerosol extinction coefficient observations

    Directory of Open Access Journals (Sweden)

    L. W. Thomason

    2012-09-01

    Full Text Available Herein, the Halogen Occultation Experiment (HALOE aerosol extinction coefficient data is evaluated in the low aerosol loading period after 1996 as the first necessary step in a process that will eventually allow the production of a combined HALOE/SAGE II (Stratospheric Aerosol and Gas Experiment aerosol climatology of derived aerosol products including surface area density. Based on these analyses, it is demonstrated that HALOE's 3.46 μm is of good quality above 19 km and suitable for scientific applications above that altitude. However, it is increasingly suspect at lower altitudes and should not be used below 17 km under any circumstances after 1996. The 3.40 μm is biased by about 10% throughout the lower stratosphere due to the failure to clear NO2 but otherwise appears to be a high quality product down to 15 km. The 2.45 and 5.26 μm aerosol extinction coefficient measurements are clearly biased and should not be used for scientific applications after the most intense parts of the Pinatubo period. Many of the issues in the aerosol data appear to be related to either the failure to clear some interfering gas species or doing so poorly. For instance, it is clear that the 3.40 μm aerosol extinction coefficient measurements can be improved through the inclusion of an NO2 correction and could, in fact, end up as the highest quality overall HALOE aerosol extinction coefficient measurement. It also appears that the 2.45 and 5.26 μm channels may be improved by updating the Upper Atmosphere Pilot Database which is used as a resource for the removal of gas species otherwise not available from direct HALOE measurements. Finally, a simple model to demonstrate the promise of mixed visible/infrared aerosol extinction coefficient ensembles for the retrieval of bulk aerosol properties demonstrates that a combined HALOE/SAGE II aerosol climatology is feasible and may represent a substantial improvement over independently derived

  1. Interaction cross section study of the two-neutron halo nucleus 22C

    Directory of Open Access Journals (Sweden)

    Y. Togano

    2016-10-01

    Full Text Available The interaction cross sections (σI of the very neutron-rich carbon isotopes 19C, 20C and 22C have been measured on a carbon target at 307, 280, and 235 MeV/nucleon, respectively. A σI of 1.280±0.023 b was obtained for 22C, significantly larger than for 19,20C, supporting the halo character of 22C. A 22C root-mean-squared matter radius of 3.44±0.08 fm was deduced using a four-body Glauber reaction model. This value is smaller than an earlier estimate (of 5.4±0.9 fm derived from a σI measurement on a hydrogen target at 40 MeV/nucleon. These new, higher-precision σI data provide stronger constraints for assessing the consistency of theories describing weakly bound nuclei.

  2. Are the supergiant halos experimental evidence for the pionic radioactivity?

    Science.gov (United States)

    Ion, D. B.; Ion-Mihai, R.

    1994-10-01

    Pionic radiohalos (PIRH), as an integral time record of the pionic nuclear radioactivity of the heavy nuclides with Z > 80 from the inclusions from ancient minerals, are introduced. It is then shown that the essential characteristic features of the observed supergiant halos (SGH) are reproduced with a surprisingly high accuracy by those of the pionic radiohalos. For the clarification of this problem new experimental investigations including pionic detection methods are suggested.

  3. Mapping Milky Way Halo Structure with Blue Horizontal Branch Stars

    Science.gov (United States)

    Martin, Charles; Newberg, Heidi Jo; Carlin, Jeffrey L.

    2017-01-01

    The use of blue horizontal brach (BHB) and red giant branch stars as tracers of stellar debris streams is a common practice and has been useful in the confirmation of kinematic properties of previously identified streams. This work explores less common ways of untangling the velocity signatures of streams traveling radially to our line of sight, and to peer toward the higher density region of the Galactic Center using data from the Sloan Digital Sky Survey (SDSS). Using spectra of BHB stars, we are able to kinematically distinguish moving groups in the Milky Way halo. The results of this thesis advance our knowledge of the following stellar halo substructures: the Pisces Stellar Stream, the Hercules-Aquila Cloud, the Hercules Halo Stream, and the Hermus Stream. A study of red giant stars led to the kinematic discovery of the Pisces Stellar Stream. Red giant stars were also examined to determine that the previously identified velocity signature that was suggested for the Hercules-Aquila Cloud was due to disk star contamination and errors in preliminary SDSS velocities. The Hercules Halo Stream is a previously unidentified structure that could be related to the Hercules-Aquila Cloud, and was discovered as a velocity excess of SDSS BHB stars. We identify a group of 10 stars with similar velocities that are spatially coincident with the Hermus Stream. An orbit is fit to the Hermus Stream that rules out a connection with the Phoenix Stream.This work was supported by NSF grants AST 09-37523, 14-09421, 16-15688, the NASA/NY Space Grant fellowship, and contributions made by The Marvin Clan, Babette Josephs, Manit Limlamai, and the 2015 Crowd Funding Campaign to Support Milky Way Research.

  4. The Connection between Radio Halos and Cluster Mergers and the ...

    Indian Academy of Sciences (India)

    and the Statistical Properties of the Radio Halo Population. R. Cassano1,2,∗. , G. Brunetti2 & T. ... sources located in the cluster central regions, with spatial extent similar to that of the hot ICM and steep radio spectra, α > 1.1 ... distribution of clusters in the P1.4 − LX diagram (Brunetti et al. 2007): RH trace the well-known ...

  5. Can $\\beta$-decay probe excited state halos?

    CERN Multimedia

    2002-01-01

    In the first experiment at the newly constructed ISOLDE Facility the first-forbidden $\\beta$-decay of $^{17}$Ne into the first excited state of $^{17}$F has been measured. It is a factor two faster than the corresponding mirror decay and thus gives one of the largest recorded asymmetries for $\\beta$-decays feeding bound final states. Shell-model calculations can only reproduce the asymmetry if the halo structure of the $^{17}$F state is taken into account.

  6. The Effects of Varying Cosmological Parameters on Halo Substructure

    Science.gov (United States)

    Dooley, Gregory A.; Griffen, Brendan F.; Zukin, Phillip; Ji, Alexander P.; Vogelsberger, Mark; Hernquist, Lars E.; Frebel, Anna

    2014-05-01

    We investigate how different cosmological parameters, such as those delivered by the WMAP and Planck missions, affect the nature and evolution of the dark matter halo substructure. We use a series of flat Λ cold dark matter cosmological N-body simulations of structure formation, each with a different power spectrum but with the same initial white noise field. Our fiducial simulation is based on parameters from the WMAP seventh year cosmology. We then systematically vary the spectral index, ns ; matter density, Ω M ; and normalization of the power spectrum, σ8, for seven unique simulations. Across these, we study variations in the subhalo mass function, mass fraction, maximum circular velocity function, spatial distribution, concentration, formation times, accretion times, and peak mass. We eliminate dependence of subhalo properties on host halo mass and average the values over many hosts to reduce variance. While the "same" subhalos from identical initial overdensity peaks in higher σ8, ns , and Ω m simulations accrete earlier and end up less massive and closer to the halo center at z = 0, the process of continuous subhalo accretion and destruction leads to a steady state distribution of these properties across all subhalos in a given host. This steady state mechanism eliminates cosmological dependence on all of the properties listed above except for subhalo concentration and V max, which remain greater for higher σ8, ns , and Ω m simulations, and subhalo formation time, which remains earlier. We also find that the numerical technique for computing the scale radius and the halo finder that were used can significantly affect the concentration-mass relationship as computed for a simulation.

  7. A multi-machine scaling of halo current rotation

    Science.gov (United States)

    Myers, C. E.; Eidietis, N. W.; Gerasimov, S. N.; Gerhardt, S. P.; Granetz, R. S.; Hender, T. C.; Pautasso, G.; Contributors, JET

    2018-01-01

    Halo currents generated during unmitigated tokamak disruptions are known to develop rotating asymmetric features that are of great concern to ITER because they can dynamically amplify the mechanical stresses on the machine. This paper presents a multi-machine analysis of these phenomena. More specifically, data from C-Mod, NSTX, ASDEX Upgrade, DIII-D, and JET are used to develop empirical scalings of three key quantities: (1) the machine-specific minimum current quench time, \

  8. Towards high precision measurements of nuclear g-factors for the Be isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Takamine, A., E-mail: icot@riken.jp [RIKEN, Nishina Center for Accelerator Based Science, Wako City, Saitama (Japan); Wada, M. [RIKEN, Nishina Center for Accelerator Based Science, Wako City, Saitama (Japan); Okada, K. [Department of Physics, Sophia University, Chiyoda Ward, Tokyo (Japan); Ito, Y. [RIKEN, Nishina Center for Accelerator Based Science, Wako City, Saitama (Japan); Schury, P.; Arai, F. [RIKEN, Nishina Center for Accelerator Based Science, Wako City, Saitama (Japan); Institute of Physics, University of Tsukuba, Tsukuba City, Ibaraki (Japan); Katayama, I. [RIKEN, Nishina Center for Accelerator Based Science, Wako City, Saitama (Japan); Imamura, K. [RIKEN, Nishina Center for Accelerator Based Science, Wako City, Saitama (Japan); Department of Physics, Meiji University, Kawasaki City, Kanagawa (Japan); Ichikawa, Y.; Ueno, H. [RIKEN, Nishina Center for Accelerator Based Science, Wako City, Saitama (Japan); Wollnik, H. [Department of Chemistry and BioChemistry, New Mexico State University, Las Cruces, NM (United States); Schuessler, H.A. [Department of Physics, Texas A& M University, College Station, TX (United States)

    2016-06-01

    We describe the present status of future high-precision measurements of nuclear g-factors utilizing laser-microwave double and laser-microwave-rf triple resonance methods for online-trapped, laser-cooled radioactive beryllium isotope ions. These methods have applicability to other suitably chosen isotopes and for beryllium show promise in deducing the hyperfine anomaly of {sup 11}Be with a sufficiently high precision to study the nuclear magnetization distribution of this one-neutron halo nucleus in a nuclear-model-independent manner.

  9. Towards high precision measurements of nuclear g-factors for the Be isotopes

    Science.gov (United States)

    Takamine, A.; Wada, M.; Okada, K.; Ito, Y.; Schury, P.; Arai, F.; Katayama, I.; Imamura, K.; Ichikawa, Y.; Ueno, H.; Wollnik, H.; Schuessler, H. A.

    2016-06-01

    We describe the present status of future high-precision measurements of nuclear g-factors utilizing laser-microwave double and laser-microwave-rf triple resonance methods for online-trapped, laser-cooled radioactive beryllium isotope ions. These methods have applicability to other suitably chosen isotopes and for beryllium show promise in deducing the hyperfine anomaly of 11Be with a sufficiently high precision to study the nuclear magnetization distribution of this one-neutron halo nucleus in a nuclear-model-independent manner.

  10. A look into the inside of haloes: a characterization of the halo shape as a function of overdensity in the Planck cosmology

    Science.gov (United States)

    Despali, Giulia; Giocoli, Carlo; Bonamigo, Mario; Limousin, Marceau; Tormen, Giuseppe

    2017-04-01

    In this paper, we study the triaxial properties of dark matter haloes of a wide range of masses extracted from a set of cosmological N-body simulations. We measure the shape at different distances from the halo centre (characterized by different overdensity thresholds), both in three and in two dimensions. We discuss how halo triaxiality increases with mass, redshift and distance from the halo centre. We also examine how the orientations of the different ellipsoids are aligned with each other and what is the gradient in internal shapes for haloes with different virial configurations. Our findings highlight that the internal part of the halo retains memory of the violent formation process keeping the major axis oriented towards the preferential direction of the infalling material while the outer part becomes rounder due to continuous isotropic merging events. This effect is clearly evident in high-mass haloes - which formed more recently - while it is more blurred in low-mass haloes. We present simple distributions that may be used as priors for various mass reconstruction algorithms, operating in different wavelengths, in order to recover a more complex and realistic dark matter distribution of isolated and relaxed systems.

  11. Decay Properties of the Halo Nucleus $^{11}$Li

    CERN Multimedia

    2002-01-01

    During the past years a considerable experimental effort has been devoted to the production and study of nuclei close to the neutron and proton drip-lines. The most spectacular phenomenon encountered is the occurrence of neutron halos in the loosely bound neutron rich nuclei. \\\\ \\\\ Another interesting feature, observed at ISOLDE, which most likely is connected to the halo structure, is the very strong (super-allowed) Gamow-Teller $\\beta$- transitions to highly excited states which are systematically observed for the lightest neutron rich drip-line nuclei. These transitions might be viewed as arising from the quasi-free $\\beta$ -decay of the halo neutrons. It is proposed to make a detailed study of the $\\beta$- strength function for $^{11}$Li, a nuclide having a half-life of 8.2 ms and a Q $\\beta$-value of 20.73~MeV. \\\\ \\\\ So far only a lower limit of the Gamow-Teller transition rate to highly excited states ($\\approx$~18.5~MeV) in the daughter nucleus has been obtained from measurements of $\\beta$-delayed tri...

  12. KINEMATICS OF OUTER HALO GLOBULAR CLUSTERS IN M31

    Energy Technology Data Exchange (ETDEWEB)

    Veljanoski, J.; Ferguson, A. M. N.; Bernard, E. J.; Penarrubia, J. [Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Mackey, A. D. [Research School of Astronomy and Astrophysics, Australian National University, Mt Stromlo Observatory, Weston Creek, ACT 2611 (Australia); Huxor, A. P. [Astronomisches Rechen-Institut, Zentrum fur Astronomie der Universitat Heidelberg, Monchhofstr. 12-14, D-69120 Heidelberg (Germany); Irwin, M. J.; Chapman, S. C. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Cote, P. [NRC Herzberg Institute of Astrophysics, 5071 West Saanich Road, Victoria, British Columbia V9E 2E7 (Canada); Tanvir, N. R.; McConnachie, A. [Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH (United Kingdom); Ibata, R. A.; Martin, N. F. [Observatoire de Strasbourg, 11 rue de l' Universite, F-67000 Strasbourg (France); Fardal, M. [University of Massachusetts, Department of Astronomy, LGRT 619-E, 710 N. Pleasant Street, Amherst, MA 01003-9305 (United States); Lewis, G. F. [Institute of Astronomy, School of Physics, University of Sydney, NSW 2006 (Australia)

    2013-05-10

    We present the first kinematic analysis of the far outer halo globular cluster (GC) population in the Local Group galaxy M31. Our sample contains 53 objects with projected radii of {approx}20-130 kpc, 44 of which have no previous spectroscopic information. GCs with projected radii {approx}> 30 kpc are found to exhibit net rotation around the minor axis of M31, in the same sense as the inner GCs, albeit with a smaller amplitude of 79 {+-} 19 km s{sup -1}. The rotation-corrected velocity dispersion of the full halo GC sample is 106 {+-} 12 km s{sup -1}, which we observe to decrease with increasing projected radius. We find compelling evidence for kinematic coherence among GCs that project on top of halo substructure, including a clear signature of infall for GCs lying along the northwest stream. Using the tracer mass estimator, we estimate the dynamical mass of M31 within 200 kpc to be M{sub M31} = (1.2-1.5) {+-} 0.2 Multiplication-Sign 10{sup 12} M{sub Sun }. This value is highly dependent on the chosen model and assumptions within.

  13. Hypervelocity Stars: From the Galactic Center to the Halo

    Science.gov (United States)

    Kenyon, Scott J.; Bromley, Benjamin C.; Geller, Margaret J.; Brown, Warren R.

    2008-06-01

    Hypervelocity stars (HVSs) traverse the Galaxy from the central black hole to the outer halo. We show that the Galactic potential within 200 pc acts as a high-pass filter preventing low-velocity HVSs from reaching the halo. To trace the orbits of HVSs throughout the Galaxy, we construct two forms of the potential which reasonably represent the observations in the range 5-105 pc: a simple spherically symmetric model and a bulge-disk-halo model. We use the Hills mechanism (disruption of binaries by the tidal field of the central black hole) to inject HVSs into the Galaxy and to compute the observable spatial and velocity distributions of HVSs with masses in the range 0.6-4 M⊙. These distributions reflect the mass function in the Galactic center, properties of binaries in the Galactic center, and aspects of stellar evolution and the injection mechanism. For 0.6-4 M⊙ main-sequence stars, the fraction of unbound HVSs and the asymmetry of the velocity distribution for their bound counterparts increase with stellar mass. The density profiles for unbound HVSs decline with distance from the Galactic center approximately as r-2 (but are steeper for the most massive stars, which evolve off the main sequence during their travel time from the Galactic center); the density profiles for the bound ejecta decline with distance approximately as r-3. In a survey with a limiting magnitude of Vlesssim 23, the detectability of HVSs (unbound or bound) increases with stellar mass.

  14. Integrated Marketing Communications (IMC di PT Halo Rumah Bernyanyi

    Directory of Open Access Journals (Sweden)

    Rebekka Rismayanti

    2017-01-01

    Full Text Available Abstract: This research aims to describe the effectiveness of Integrated Marketing Communication (IMC in PT Halo Rumah Bernyanyi which, from the perspective of marketing strategy, could be studied by analyzing the segmentation, targeting, and positioning. Using case-study method with in-depth interview, the result shows that the implementation of IMC at PT Halo Rumah Bernyayi is arranged in one single strategy and tend to neglect the complexities of running multi-brand family karaoke-house. This considers as ineffective because it leads to “cannibalization” among brands, especially when costumer’s targetting is overlooked before drafting the IMC plan. Keywords: Business, Integrated Marketing Communication, Marketing   Abstrak: Penelitian ini bertujuan untuk mendeskripsikan efektivitas penerapan Integrated Marketing Communications (IMC yang dilihat dari aspek segmentation, targeting dan positioning. Metode penelitian adalah studi kasus dengan menggunakan wawancara mendalam. Hasil penelitian menunjukkan bahwa penerapan IMC di PT Halo Rumah Bernyanyi dibuat dalam satu strategi dan tidak memerhatikan kompleksitas dari aspek segmentation, targeting dan positioning sebagai pedoman dasar. Langkah tersebut dinilai tidak efektif karena dapat mengakibatkan “kanibalisasi” antar brand, terlebih jika perhatian terhadap target konsumen diabaikan sebelum menyusun perencanaan IMC. Kata Kunci: Bisnis, Integrated Marketing Communications, Pemasaran

  15. Design alternatives for beam halo monitors in high intensity accelerators

    CERN Document Server

    Braun, H; Corsini, R; Lefèvre, T; Schulte, Daniel; Tecker, F A; Welsch, C P

    2005-01-01

    In future high intensity, high energy accelerators it must be ensured that particle losses are minimized as activation of the vacuum chambers or other components makes maintenance and upgrade work time consuming and costly. It is imperative to have a clear understanding of the mechanisms that can lead to halo formation and to have the possibility to test available theoretical models with an adequate experimental setup. Optical transition radiation (OTR) provides an interesting opportunity for linear real-time measurements of the transverse beam profile with a resolution which has been so far at best in the some μm range. However, the dynamic range of standard OTR systems is typically limited and needs to be improved for its application for halo measurements. In this contribution, the existing OTR system as it is installed in the CLIC test facility (CTF3) is analyzed and the contribution of each component to the final image quality discussed. Finally, possible halo measurement techniques based on OTR are pres...

  16. Detecting Hot Gaseous Halos of Galaxies with Arcus

    Science.gov (United States)

    Bregman, Joel N.; Hodges-Kluck, Edmund; Li, Jiangtao; Li, Yunyang; Miller, Matthew; Qu, Zhijie

    2018-01-01

    A long-lived component of galaxies is the hot extended atmosphere with a temperature near the virial temperature. It can contain a significant fraction of the missing baryons and can act as a reservoir of matter for future generations of stars. This extended hot halo is detected around the Milky Way in absorption and emission lines of highly ionized species (e.g., O VII, O VIII), but weighted to be within about 50 kpc. From current data there are not many high fidelity absorption line detections and the lines are badly under-resolved. These shortcomings will be rectified with Arcus, which will provide high-quality line measurements in several ions for about 50 sight lines. Lines will often be resolved, revealing the dynamics of the hot halo, such as rotation and the turbulence resulting from feedback. We show how metallicities will be determined from a comparison of these absorption lines with existing emission line data. Arcus will detect O VII absorption from similar halos around external galaxies, for the first time, and out to ~R200, if not beyond. Using random lines of sight, Arcus will complete the metal census of the Universe.

  17. Dwarf Galaxies in Voids: Dark Matter Halos and Gas Cooling

    Directory of Open Access Journals (Sweden)

    Matthias Hoeft

    2010-01-01

    Full Text Available Galaxy surveys have shown that luminous galaxies are mainly distributed in large filaments and galaxy clusters. The remaining large volumes are virtually devoid of luminous galaxies. This is in concordance with the formation of the large-scale structure in the universe as derived from cosmological simulations. However, the numerical results indicate that cosmological voids are abundantly populated with dark matter haloes which may in principle host dwarf galaxies. Observational efforts have in contrast revealed that voids are apparently devoid of dwarf galaxies. We investigate the formation of dwarf galaxies in voids by hydrodynamical cosmological simulations. Due to the cosmic ultraviolet background radiation low-mass haloes show generally a reduced baryon fraction. We determine the characteristic mass below which dwarf galaxies are baryon deficient. We show that the circular velocity below which the accretion of baryons is suppressed is approximately 40 kms−1. The suppressed baryon accretion is caused by the photo-heating due to the UV background. We set up a spherical halo model and show that the effective equation of the state of the gas in the periphery of dwarf galaxies determines the characteristic mass. This implies that any process which heats the gas around dwarf galaxies increases the characteristic mass and thus reduces the number of observable dwarf galaxies.

  18. Ultra-Deep Imaging: Structure of Disks and Haloes

    Science.gov (United States)

    Knapen, Johan H.; Trujillo, Ignacio

    Deep imaging is a fundamental tool in the study of the outermost structures of galaxies. We review recent developments in ultra-deep imaging of galaxy disks and haloes, highlighting the technical advances as well as the challenges and summarizing observational results in the context of modern theory and simulations. The deepest modern galaxy imaging comes from three main sources: (1) surveys such as the Sloan Digital Sky Survey's Stripe 82 project; (2) very long exposures on small telescopes, including by amateurs; and (3) long exposures on the largest professional telescopes. The technical challenges faced are common in all these approaches and include the treatment of light scattered by atmosphere and telescope/instrument, correct flat fielding and the subtraction of non-galaxy light in the images. We review scientific results on galaxy disks and haloes obtained with deep imaging, including the detection and characterization of stellar haloes, tidal features and stellar streams, disk truncations and thick disks. The area of ultra-deep imaging is still very much unexplored territory, and future work in this area promises significant advances in our understanding of galaxy formation and evolution.

  19. Shot noise and biased tracers: A new look at the halo model

    Science.gov (United States)

    Ginzburg, Dimitry; Desjacques, Vincent; Chan, Kwan Chuen

    2017-10-01

    Shot noise is an important ingredient to any measurement or theoretical modeling of discrete tracers of the large scale structure. Recent work has shown that the shot noise in the halo power spectrum becomes increasingly sub-Poissonian at high mass. Interestingly, while the halo model predicts a shot noise power spectrum in qualitative agreement with the data, it leads to an unphysical white noise in the cross halo-matter and matter power spectrum. In this work, we show that absorbing all the halo model sources of shot noise into the halo fluctuation field leads to meaningful predictions for the shot noise contributions to halo clustering statistics and remove the unphysical white noise from the cross halo-matter statistics. Our prescription straightforwardly maps onto the general bias expansion, so that the renormalized shot noise terms can be expressed as combinations of the halo model shot noises. Furthermore, we demonstrate that non-Poissonian contributions are related to volume integrals over correlation functions and their response to long-wavelength density perturbations. This leads to a new class of consistency relations for discrete tracers, which appear to be satisfied by our reformulation of the halo model. We test our theoretical predictions against measurements of halo shot noise bispectra extracted from a large suite of numerical simulations. Our model reproduces qualitatively the observed sub-Poissonian noise, although it underestimates the magnitude of this effect.

  20. Merger Histories of Galaxy Halos and Implications for Disk Survival

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, Kyle R.; Bullock, James S.; Wechsler, Risa H.; Maller, Ariyeh H.; Zentner, Andrew R.

    2008-05-16

    The authors study the merger histories of galaxy dark matter halos using a high resolution {Lambda}CDM N-body simulation. The merger trees follow {approx} 17,000 halos with masses M{sub 0} = (10{sup 11} - 10{sup 13})h{sup -1}M{sub {circle_dot}} at z = 0 and track accretion events involving objects as small as m {approx_equal} 10{sup 10} h{sup -1}M{sub {circle_dot}}. They find that mass assembly is remarkably self-similar in m/M{sub 0}, and dominated by mergers that are {approx}10% of the final halo mass. While very large mergers, m {approx}> 0.4 M{sub 0}, are quite rare, sizeable accretion events, m {approx} 0.1 M{sub 0}, are common. Over the last {approx} 10 Gyr, an overwhelming majority ({approx} 95%) of Milky Way-sized halos with M{sub 0} = 10{sup 12} h{sup -1}M{sub {circle_dot}} have accreted at least one object with greater total mass than the Milky Way disk (m > 5 x 10{sup 10} h{sup -1}M{sub {circle_dot}}), and approximately 70% have accreted an object with more than twice that mass (m > 10{sup 11} h{sup -1}M{sub {circle_dot}}). The results raise serious concerns about the survival of thin-disk dominated galaxies within the current paradigm for galaxy formation in a {Lambda}CDM universe. in order to achieve a {approx} 70% disk-dominated fraction in Milky Way-sized {Lambda}CDM halos, mergers involving m {approx_equal} 2 x 10{sup 11} h{sup -1}M{sub {circle_dot}} objects must not destroy disks. Considering that most thick disks and bulges contain old stellar populations, the situation is even more restrictive: these mergers must not heat disks or drive gas into their centers to create young bulges.

  1. METHOD OF ISOTOPE CONCENTRATION

    Science.gov (United States)

    Spevack, J.S.

    1957-04-01

    An isotope concentration process is described which consists of exchanging, at two or more different temperature stages, two isotopes of an element between substances that are physically separate from each other and each of which is capable of containing either of the isotopes, and withdrawing from a point between at least two of the temperatare stages one of the substances containing an increased concentration of the desired isotope.

  2. Following the Cosmic Evolution of Pristine Gas. I. Implications for Milky Way Halo Stars

    Science.gov (United States)

    Sarmento, Richard; Scannapieco, Evan; Pan, Liubin

    2017-01-01

    We make use of a new subgrid model of turbulent mixing to accurately follow the cosmological evolution of the first stars, the mixing of their supernova (SN) ejecta, and the impact on the chemical composition of the Galactic Halo. Using the cosmological adaptive mesh refinement code ramses, we implement a model for the pollution of pristine gas as described in Pan et al. Tracking the metallicity of Pop III stars with metallicities below a critical value allows us to account for the fraction of Zmetallicity is well above {Z}{crit}. We demonstrate that such partially mixed regions account for 0.5 to 0.7 of all Pop III stars formed up to z = 5. Additionally, we track the creation and transport of “primordial metals” (PM) generated by Pop III SNe. These neutron-capture deficient metals are taken up by second-generation stars and likely lead to unique abundance signatures characteristic of carbon-enhanced, metal-poor (CEMP-no) stars. As an illustrative example, we associate primordial metals with abundance ratios used by Keller et al. to explain the source of metals in the star SMSS J031300.36-670839.3, finding good agreement with the observed [Fe/H], [C/H], [O/H], and [Mg/Ca] ratios in CEMP-no Milky Way halo stars. Similar future simulations will aid in further constraining the properties of Pop III stars using CEMP observations, as well as improve predictions of the spatial distribution of Pop III stars, as will be explored by the next generation of ground- and space-based telescopes.

  3. Galaxy power spectrum in redshift space: Combining perturbation theory with the halo model

    Science.gov (United States)

    Okumura, Teppei; Hand, Nick; Seljak, Uroš; Vlah, Zvonimir; Desjacques, Vincent

    2015-11-01

    Theoretical modeling of the redshift-space power spectrum of galaxies is crucially important to correctly extract cosmological information from galaxy redshift surveys. The task is complicated by the nonlinear biasing and redshift space distortion (RSD) effects, which change with halo mass, and by the wide distribution of halo masses and their occupations by galaxies. One of the main modeling challenges is the existence of satellite galaxies that have both radial distribution inside the halos and large virial velocities inside halos, a phenomenon known as the Finger-of-God (FoG) effect. We present a model for the redshift-space power spectrum of galaxies in which we decompose a given galaxy sample into central and satellite galaxies and relate different contributions to the power spectrum to 1-halo and 2-halo terms in a halo model. Our primary goal is to ensure that any parameters that we introduce have physically meaningful values, and are not just fitting parameters. For the lowest order 2-halo terms we use the previously developed RSD modeling of halos in the context of distribution function and perturbation theory approach. This term needs to be multiplied by the effect of radial distances and velocities of satellites inside the halo. To this one needs to add the 1-halo terms, which are nonperturbative. We show that the real space 1-halo terms can be modeled as almost constant, with the finite extent of the satellites inside the halo inducing a small k2R2 term over the range of scales of interest, where R is related to the size of the halo given by its halo mass. We adopt a similar model for FoG in redshift space, ensuring that FoG velocity dispersion is related to the halo mass. For FoG k2 type expansions do not work over the range of scales of interest and FoG resummation must be used instead. We test several simple damping functions to model the velocity dispersion FoG effect. Applying the formalism to mock galaxies modeled after the "CMASS" sample of the

  4. Non-local thermodynamic equilibrium stellar spectroscopy with 1D and 3D models - II. Chemical properties of the Galactic metal-poor disk and the halo

    DEFF Research Database (Denmark)

    Bergemann, Maria; Collet, Remo; Schönrich, Ralph

    2016-01-01

    /Fe] ratios close to solar even at [Fe/H] ~ -2. This is at variance with results of classical abundance analyses based on local thermodynamic equilibrium (LTE) and 1D model stellar atmospheres, which argue for a constant elevated [Mg/Fe] in metal-poor stars of the Galactic thick disk and halo.......We have analysed high-resolution spectra of 328 stars and derived Mg abundances using non-local thermodynamic equilibrium (NLTE) spectral line formation calculations and plane-parallel model stellar atmospheres derived from the mean stratification of 3D hydrodynamical surface convection simulations...

  5. New HST Observations of the Halo Gas of NGC 3067: Limits on the Extragalactic Ionizing Background at Low Redshift and the Lyman Continuum Escape Fraction

    OpenAIRE

    Tumlinson, Jason; Giroux, Mark L.; Shull, J. Michael; Stocke, John T.

    1999-01-01

    We present UV spectroscopy from HST/GHRS and reanalyze existing H_alpha images of the quasar/galaxy pair 3C 232/NGC 3067 and of the halo gas associated with NGC 3067. The spectra permit measurement of, or limits on, the column densities of Fe I, Fe II, Mg I, and Mg II in the absorbing cloud. Two distinct models of the extragalactic radiation field are considered: (1) the ionizing spectrum is dominated by a power-law extragalactic continuum, and (2) the power-law spectrum contains a Lyman brea...

  6. The formation of the Milky Way halo and its dwarf satellites; a NLTE-1D abundance analysis. II. Early chemical enrichment

    Science.gov (United States)

    Mashonkina, L.; Jablonka, P.; Sitnova, T.; Pakhomov, Yu.; North, P.

    2017-12-01

    We present the non-local thermodynamic equilibrium (NLTE) abundances of up to 10 chemical species in a sample of 59 very metal-poor (VMP, -4 ≤ [Fe/H] ≾-2) stars in seven dwarf spheroidal galaxies (dSphs) and in the Milky Way (MW) halo. Our results are based on high-resolution spectroscopic datasets and homogeneous and accurate atmospheric parameters determined in Paper I. We show that once the NLTE effects are properly taken into account, all massive galaxies in our sample, that is, the MW halo and the classical dSphs Sculptor, Ursa Minor, Sextans, and Fornax, reveal a similar plateau at [α/Fe] ≃ 0.3 for each of the α-process elements: Mg, Ca, and Ti. We put on a firm ground the evidence for a decline in α/Fe with increasing metallicity in the Boötes I ultra-faint dwarf galaxy (UFD), that is most probably due to the ejecta of type Ia supernovae. For Na/Fe, Na/Mg, and Al/Mg, the MW halo and all dSphs reveal indistinguishable trends with metallicity, suggesting that the processes of Na and Al synthesis are identical in all systems, independent of their mass. The dichotomy in the [Sr/Ba] versus [Ba/H] diagram is observed in the classical dSphs, similarly to the MW halo, calling for two different nucleosynthesis channels for Sr. We show that Sr in the massive galaxies is well correlated with Mg suggesting a strong link to massive stars and that its origin is essentially independent of Ba, for most of the [Ba/H] range. Our three UFDs, that is Boötes I, UMa II, and Leo IV, are depleted in Sr and Ba relative to Fe and Mg, with very similar ratios of [Sr/Mg] ≃-1.3 and [Ba/Mg] ≃-1 on the entire range of their Mg abundances. The subsolar Sr/Ba ratios of Boötes I and UMa II indicate a common r-process origin of their neutron-capture elements. Sculptor remains the classical dSph, in which the evidence for inhomogeneous mixing in the early evolution stage, at [Fe/H] <-2, is the strongest. Full Tables 3 and 4 are only available at the CDS via anonymous ftp to

  7. Statistical clumped isotope signatures

    NARCIS (Netherlands)

    Röckmann, T.; Popa, M.E.; Krol, M.C.; Hofmann, M.E.G.

    2016-01-01

    High precision measurements of molecules containing more than one heavy isotope may provide novel constraints on element cycles in nature. These so-called clumped isotope signatures are reported relative to the random (stochastic) distribution of heavy isotopes over all available isotopocules of

  8. Statistical clumped isotope signatures

    NARCIS (Netherlands)

    Röckmann, T.|info:eu-repo/dai/nl/304838233; Popa, M. E.|info:eu-repo/dai/nl/375806407; Krol, M. C.|info:eu-repo/dai/nl/078760410; Hofmann, M. E. G.|info:eu-repo/dai/nl/374642907

    2016-01-01

    High precision measurements of molecules containing more than one heavy isotope may provide novel constraints on element cycles in nature. These so-called clumped isotope signatures are reported relative to the random (stochastic) distribution of heavy isotopes over all available isotopocules of a

  9. Statistical clumped isotope signatures

    Science.gov (United States)

    Röckmann, T.; Popa, M. E.; Krol, M. C.; Hofmann, M. E. G.

    2016-01-01

    High precision measurements of molecules containing more than one heavy isotope may provide novel constraints on element cycles in nature. These so-called clumped isotope signatures are reported relative to the random (stochastic) distribution of heavy isotopes over all available isotopocules of a molecule, which is the conventional reference. When multiple indistinguishable atoms of the same element are present in a molecule, this reference is calculated from the bulk (≈average) isotopic composition of the involved atoms. We show here that this referencing convention leads to apparent negative clumped isotope anomalies (anti-clumping) when the indistinguishable atoms originate from isotopically different populations. Such statistical clumped isotope anomalies must occur in any system where two or more indistinguishable atoms of the same element, but with different isotopic composition, combine in a molecule. The size of the anti-clumping signal is closely related to the difference of the initial isotope ratios of the indistinguishable atoms that have combined. Therefore, a measured statistical clumped isotope anomaly, relative to an expected (e.g. thermodynamical) clumped isotope composition, may allow assessment of the heterogeneity of the isotopic pools of atoms that are the substrate for formation of molecules. PMID:27535168

  10. Evidence for beta -delayed neutron emission from /sup 31/Mg and /sup 32/Mg

    CERN Document Server

    Zaidins, C S; De Saint-Simon, M; Détraz, C; Epherre-Rey-Campagnolle, Marcelle; Guillemaud, D; Klapisch, Robert; Langevin, M; Naulin, F; Thibault, C; Touchard, F

    1981-01-01

    Investigates the time spectrum of beta -delayed neutron emission from /sup 30-34/Na and their descendants using beta -neutron coincidence detection. The authors have been able to assign an upper limit of 0,4% to the probability of beta -delayed neutron emission, p/sub n/, from the /sup 30/Na daugher isotope /sup 30/Mg. In fitting the time spectra of beta -delayed neutrons from /sup 31/Na and /sup 32/Na, we find a definitive component from subsequent daughter decay as well. This provides evidence for beta -delayed neutron emission from /sup 31/Mg and /sup 32/Mg with P/sub n/ values of the order of 2% for each. (7 refs).

  11. Injection halos of hydrocarbons above oil-gas fields with super-high pressures

    Energy Technology Data Exchange (ETDEWEB)

    Bakhtin, V.V.

    1979-09-01

    We studied the origin of injection halos of hydrocarbons above oil-gas fields with anomalously high formation pressures (AHFP). Using fields in Azerbaydzhan and Chechen-Ingushetiya as an example, we demonstrate the effect of certain factors (in particular, faults and zones of increased macro- and micro-jointing) on the morpholoy of the halos. The intensity of micro-jointing (jointing permeability, three-dimensional density of micro-jointing) is directly connected with vertical dimensions of the halos. We measured halos based on transverse profiles across the Khayan-Kort field and studied the distribution of bitumen saturation within the injection halo. Discovery of injection halos during drilling has enabled us to improve the technology of wiring deep-seated exploratory wells for oil and gas in regions with development of AHFP.

  12. Hydrocarbon halo distribution above oil and gas deposits with abnormally high stratal pressures

    Energy Technology Data Exchange (ETDEWEB)

    Bakhtin, V.V.

    1978-01-01

    An examination is made of the emergence of hydrocarbon halos over oil and gas deposits with abnormally high stratal pressure. Fields in Azerbaidzhan and Checheno-Ingushetiya are used to illustrate the effect of certain factors (particularly fractures, zones with heightened macro and microfissure formation) on halo morphology. A direct relationship was found between the intensity of microfissure formation (fissure permeability, volumetric density of microfissures) and the size of vertically directed halos. Dimensions are given for halos by cross-sectional profiles of the Khayan-Kort field, and information is given on the nature of bitumen saturation distribution within the halo. The identification of halos in the process of drilling will make it possible to improve the technology of cutting deep gas and oil exploratory wells in the regions of abnormally high stratal pressures are developing. 22 references, 4 figures, 1 table.

  13. Group support system and explanatory feedback: An experimental study of mitigating halo effect

    Directory of Open Access Journals (Sweden)

    Intiyas Utami

    2015-12-01

    Full Text Available Comprehensive assessment potentially leads to halo effect that will affect accuracy of auditors decision-making process. Biased initial audit decision will potentially influence final audit decision. It is there-fore necessary to mitigate halo effect that is the consequence of auditors good impression on clients initial condition. This re-search aims to empirically show that halo effect can be mitigated by explanatory feedback and Group Support System (GSS. The researchers experimentally mani-pulate explanatory feedback and GSS using online web-site. The subjects are stu-dents who have already taken auditing courses. The results show that: 1 explanato-ry feedback can mitigate halo effect so that audit decision will be more accurate 2 GSS can also mitigate halo effect 3 explanatory feedback and GSS are the best me-thods to mitigate halo effect.

  14. HaloTag as a reporter gene: positron emission tomography imaging with 64Cu-labeled second generation HaloTag ligands

    Science.gov (United States)

    Hong, Hao; Benink, Hélène A; Uyeda, H Tetsuo; Valdovinos, Hector F; Zhang, Yin; Meisenheimer, Poncho; Barnhart, Todd E; Fan, Frank; Cai, Weibo

    2013-01-01

    The goal of this study is to employ the HaloTag technology for positron emission tomography (PET), which involves two components: the HaloTag protein (a modified hydrolase which covalently binds to synthetic ligands) and HaloTag ligands (HTLs). 4T1 murine breast cancer cells were stably transfected to express HaloTag protein on the surface (termed as 4T1-HaloTag-ECS, ECS denotes extracellular surface). Two new HTLs were synthesized and termed NOTA-HTL2G-S and NOTA-HTL2G-L (2G indicates second generation, S stands for short, L stands for long, NOTA denotes 1,4,7-triazacyclononane-N,N’N’’-triacetic acid). Microscopy studies confirmed surface expression of HaloTag in 4T1-HaloTag-ECS cells, which specifically bind NOTA-HTL2G-S/L. Uptake of 64Cu-NOTA-HTL2G-L in 4T1-HaloTag-ECS tumors (4.3 ± 0.5, 4.1± 0.2, 4.0 ± 0.2, 2.3 ± 0.1, and 2.2 ± 0.1 %ID/g at 0.5, 3, 6, 18, and 24 h post-injection respectively; n = 4) was significantly higher than that in the 4T1 tumors (3.0 ± 0.3, 3.0± 0.1, 3.0 ± 0.2, 2.0 ± 0.4, and 2.4 ± 0.3 %ID/g at 0.5, 3, 6, 18, and 24 h post-injection respectively; n = 4) at early time points. In comparison, 64Cu-NOTA-HTL2G-S did not demonstrate significant uptake in either 4T1-HaloTag-ECS or 4T1 tumors. Blocking studies and autoradiography of tumor lysates confirmed that 64Cu-NOTA-HTL2G-L binds specifically to HaloTag protein in the 4T1-HaloTag-ECS tumors, corroborated by histology. HaloTag protein-specific targeting and PET imaging in vivo with 64Cu-NOTA-HTL2G-L serves as a proof-of-principle for future non-invasive and sensitive tracking of HaloTag-transfected cells with PET, as well as many other studies of gene/protein/cell function in vivo. PMID:23634240

  15. The Impact of Assembly Bias on the Galaxy Content of Dark Matter Halos

    Science.gov (United States)

    Zehavi, Idit; Contreras, Sergio; Padilla, Nelson; Smith, Nicholas J.; Baugh, Carlton M.; Norberg, Peder

    2018-01-01

    We study the dependence of the galaxy content of dark matter halos on large-scale environment and halo formation time using semi-analytic galaxy models applied to the Millennium simulation. We analyze subsamples of halos at the extremes of these distributions and measure the occupation functions for the galaxies they host. We find distinct differences among these occupation functions. The main effect with environment is that central galaxies (and in one model, also the satellites) in denser regions start populating lower-mass halos. A similar, but significantly stronger, trend exists with halo age, where early-forming halos are more likely to host central galaxies at lower halo mass. We discuss the origin of these trends and the connection to the stellar mass–halo mass relation. We find that, at fixed halo mass, older halos and to some extent also halos in dense environments tend to host more massive galaxies. Additionally, we see a reverse trend for the occupation of satellite galaxies where early-forming halos have fewer satellites, likely due to having more time for them to merge with the central galaxy. We describe these occupancy variations in terms of the changes in the occupation function parameters, which can aid in constructing realistic mock galaxy samples. Finally, we study the corresponding galaxy auto- and cross-correlation functions of the different samples and elucidate the impact of assembly bias on galaxy clustering. Our results can inform theoretical modeling of galaxy assembly bias and attempts to detect it in the real universe.

  16. Pressure at the ISM-halo interface: A reheating frequency dependence

    Directory of Open Access Journals (Sweden)

    Ćirković M.M.

    1998-01-01

    Full Text Available The dependence of the thermal pressure of hot galactic halos on a model parameter describing the frequency of major reheating episodes during galactic history is investigated. Pressure on the interface between interstellar medium and the halo gas is especially interesting, since empirical evidence here offers one of the simplest constraints on halo models. It is shown that two-phase model of Mo & Miralda-Escudé is sufficiently robust with respect to uncertainties in the average interval between reheating.

  17. HaloTag-based purification of functional human kinases from mammalian cells.

    Science.gov (United States)

    Ohana, Rachel Friedman; Hurst, Robin; Vidugiriene, Jolanta; Slater, Michael R; Wood, Keith V; Urh, Marjeta

    2011-04-01

    Although cultured mammalian cells are preferred for producing functional mammalian proteins with appropriate post-translational modifications, purification of recombinant proteins is frequently hampered by low expression. We have addressed this by creating a new method configured specifically for mammalian cell culture that provides rapid detection and efficient purification. This approach is based on HaloTag, a protein fusion tag designed to bind rapidly, selectively and covalently to a series of synthetic ligands that can carry a variety of functional groups, including fluorescent dyes for detection or solid supports for purification. Since the binding of HaloTag to the HaloLink resin is essentially irreversible, it overcomes the equilibrium-based binding limitations associated with affinity tags and enables efficient capture and purification of target protein, even at low expression levels. The target protein is released from the HaloLink resin by specific cleavage using a TEV protease fused to HaloTag (HaloTEV), leaving both HaloTag and HaloTEV permanently attached to the resin and highly pure, tag-free protein in solution. HaloTag fluorescent ligands enable fluorescent labeling of HaloTag fusion proteins, providing a convenient way to monitor expression, and thus facilitate the identification of optimal transient transfection conditions as well as the selection of high expression stable cell lines. The capabilities of this method have been demonstrated by the efficient purification of five functional human kinases from HEK293T cells. In addition, when purifications using FLAG, 3xFLAG, His(6)Tag and HaloTag were performed in parallel, HaloTag was shown to provide significantly higher yields, purity and overall recovery of the expressed proteins. Copyright © 2010 Elsevier Inc. All rights reserved.

  18. HaloTag: a novel reporter gene for positron emission tomography.

    Science.gov (United States)

    Hong, Hao; Benink, Hélène A; Zhang, Yin; Yang, Yunan; Uyeda, H Tetsuo; Engle, Jonathan W; Severin, Gregory W; McDougall, Mark G; Barnhart, Todd E; Klaubert, Dieter H; Nickles, Robert J; Fan, Frank; Cai, Weibo

    2011-08-15

    Among the many molecular imaging techniques, reporter gene imaging has been a dynamic area of research. The HaloTag protein is a modified haloalkane dehalogenase which was designed to covalently bind to synthetic ligands (i.e. the HaloTag ligands [HTL]). Covalent bond formation between the HaloTag protein and the chloroal-kane within the HTL occurs rapidly under physiological conditions, which is highly specific and essentially irreversible. Over the years, HaloTag technology has been investigated for various applications such as in vitro/in vivo imaging, protein purification/trafficking, high-throughput assays, among others. The goal of this study is to explore the use of the HaloTag protein as a novel reporter gene for positron emission tomography (PET) imaging. By attaching a HaloTag -reactive chloroalkane to 1, 4, 7-triazacyclononane-N, N', N"-triacetic acid (NOTA) through hydrophilic linkers, the resulting NOTA-conjugated HTLs were labeled with (64)Cu and tested for PET imaging in living mice bearing 4T1-HaloTag-ECS tumors, which stably express the HaloTag protein on the cell surface. Significantly higher uptake of (64)Cu-NOTA-HTL-S (which contains a short hydrophilic linker) in the 4T1-HaloTag-ECS than the non-HaloTag-expressing 4T1 tumors was observed, which demonstrated the HaloTag specificity of (64)Cu-NOTA-HTL-S and warranted future investigation of the HaloTag protein as a PET reporter gene.

  19. HaloTag Protein-Mediated Specific Labeling of Living Cells with Quantum Dots

    OpenAIRE

    So, Min-kyung; Yao, Hequan; Rao, Jianghong

    2008-01-01

    Quantum dots emerge as an attractive alternative to small molecule fluorophores as fluorescent tags for in vivo cell labeling and imaging. This communication presents a method for specific labeling of live cells using quantum dots. The labeling is mediated by HaloTag protein expressed at the cell surface which forms a stable covalent adduct with its ligand (HaloTag ligand). The labeling can be performed in one single step with quantum dot conjugates that are functionalized with HaloTag ligand...

  20. ZOMG - I. How the cosmic web inhibits halo growth and generates assembly bias

    Science.gov (United States)

    Borzyszkowski, Mikolaj; Porciani, Cristiano; Romano-Díaz, Emilio; Garaldi, Enrico

    2017-07-01

    The clustering of dark matter haloes with fixed mass depends on their formation history, an effect known as assembly bias. We use zoom N-body simulations to investigate the origin of this phenomenon. For each halo at redshift z = 0, we determine the time in which the physical volume containing its final mass becomes stable. We consider five examples for which this happens at z ˜ 1.5 and two that do not stabilize by z = 0. The zoom simulations show that early-collapsing haloes do not grow in mass at z = 0 while late-forming ones show a net inflow. The reason is that 'accreting' haloes are located at the nodes of a network of thin filaments feeding them. Conversely, each 'stalled' halo lies within a prominent filament that is thicker than the halo size. Infalling material from the surroundings becomes part of the filament while matter within it recedes from the halo. We conclude that assembly bias originates from quenching halo growth due to tidal forces following the formation of non-linear structures in the cosmic web, as previously conjectured in the literature. Also the internal dynamics of the haloes change: the velocity anisotropy profile is biased towards radial (tangential) orbits in accreting (stalled) haloes. Our findings reveal the cause of the yet unexplained dependence of halo clustering on the anisotropy. Finally, we extend the excursion-set theory to account for these effects. A simple criterion based on the ellipticity of the linear tidal field combined with the spherical-collapse model provides excellent predictions for both classes of haloes.

  1. Isotopes in heterogeneous catalysis

    CERN Document Server

    Hargreaves, Justin SJ

    2006-01-01

    The purpose of this book is to review the current, state-of-the-art application of isotopic methods to the field of heterogeneous catalysis. Isotopic studies are arguably the ultimate technique in in situ methods for heterogeneous catalysis. In this review volume, chapters have been contributed by experts in the field and the coverage includes both the application of specific isotopes - Deuterium, Tritium, Carbon-14, Sulfur-35 and Oxygen-18 - as well as isotopic techniques - determination of surface mobility, steady state transient isotope kinetic analysis, and positron emission profiling.

  2. High-resolution disruption halo current measurements using Langmuir probes in Alcator C-Mod

    Science.gov (United States)

    Tinguely, R. A.; Granetz, R. S.; Berg, A.; Kuang, A. Q.; Brunner, D.; LaBombard, B.

    2018-01-01

    Halo currents generated during disruptions on Alcator C-Mod have been measured with Langmuir ‘rail’ probes. These rail probes are embedded in a lower outboard divertor module in a closely-spaced vertical (poloidal) array. The dense array provides detailed resolution of the spatial dependence (~1 cm spacing) of the halo current distribution in the plasma scrape-off region with high time resolution (400 kHz digitization rate). As the plasma limits on the outboard divertor plate, the contact point is clearly discernible in the halo current data (as an inversion of current) and moves vertically down the divertor plate on many disruptions. These data are consistent with filament reconstructions of the plasma boundary, from which the edge safety factor of the disrupting plasma can be calculated. Additionally, the halo current ‘footprint’ on the divertor plate is obtained and related to the halo flux width. The voltage driving halo current and the effective resistance of the plasma region through which the halo current flows to reach the probes are also investigated. Estimations of the sheath resistance and halo region resistivity and temperature are given. This information could prove useful for modeling halo current dynamics.

  3. Estimating the geoeffectiveness of halo CMEs from associated solar and IP parameters using neural networks

    Directory of Open Access Journals (Sweden)

    J. Uwamahoro

    2012-06-01

    Full Text Available Estimating the geoeffectiveness of solar events is of significant importance for space weather modelling and prediction. This paper describes the development of a neural network-based model for estimating the probability occurrence of geomagnetic storms following halo coronal mass ejection (CME and related interplanetary (IP events. This model incorporates both solar and IP variable inputs that characterize geoeffective halo CMEs. Solar inputs include numeric values of the halo CME angular width (AW, the CME speed (Vcme, and the comprehensive flare index (cfi, which represents the flaring activity associated with halo CMEs. IP parameters used as inputs are the numeric peak values of the solar wind speed (Vsw and the southward Z-component of the interplanetary magnetic field (IMF or Bs. IP inputs were considered within a 5-day time window after a halo CME eruption. The neural network (NN model training and testing data sets were constructed based on 1202 halo CMEs (both full and partial halo and their properties observed between 1997 and 2006. The performance of the developed NN model was tested using a validation data set (not part of the training data set covering the years 2000 and 2005. Under the condition of halo CME occurrence, this model could capture 100% of the subsequent intense geomagnetic storms (Dst ≤ −100 nT. For moderate storms (−100 < Dst ≤ −50, the model is successful up to 75%. This model's estimate of the storm occurrence rate from halo CMEs is estimated at a probability of 86%.

  4. HaloTag: a new versatile reporter gene system in plant cells.

    Science.gov (United States)

    Lang, Christina; Schulze, Jutta; Mendel, Ralf-R; Hänsch, Robert

    2006-01-01

    HaloTag Interchangeable Labeling Technology (HaloTag) was originally developed for mammalian cell analysis. In this report, the use of HaloTag is demonstrated in plant cells for the first time. This system allows different fluorescent colours to be used to visualize the localization of the non-fluorescent HaloTag protein within living cells. A vector was constructed which expresses the HaloTag protein under the control of the 35S promoter of cauliflower mosaic virus. The functionality of the HaloTag construct was tested in transient assays by (i) transforming tobacco protoplasts and (ii) using biolistic transformation of intact leaf cells of tobacco and poplar plants. Two to fourteen days after transformation, the plant material was incubated with ligands specific for labelling the HaloTag protein, and fluorescence was visualized by confocal laser scanning microscopy. The results demonstrate that HaloTag technology is a flexible system which generates efficient fluorescence in different types of plant cells. The ligand-specific labelling of HaloTag protein was not hampered by the plant cell wall.

  5. Discovering Protein Interactions and Characterizing Protein Function Using HaloTag Technology

    National Research Council Canada - National Science Library

    Daniels, Danette L; Méndez, Jacqui; Benink, Hélène; Niles, Andrew; Murphy, Nancy; Ford, Michael; Jones, Richard; Amunugama, Ravi; Allen, David; Urh, Marjeta

    2014-01-01

    .... To specifically address the challenges of understanding the human proteome, we have developed HaloTag technology for protein isolation, particularly strong for isolation of multiprotein complexes...

  6. Chromium isotope variations

    DEFF Research Database (Denmark)

    D'Arcy, Joan Mary

    Chromium (Cr) stable isotopes are a useful tracer of changes in redox conditions because changes in its oxidation state are accompanied by an isotopic fractionation. For this reason the Cr isotope system is being developed as a potential tool for paleo-redox reconstruction. Dissolved Cr in seawater...... is incorporated into carbonates. Hence, ancient carbonates can potentially record the Cr isotopic composition (δ53Cr ‰) of seawater in the geological past. Reliable application and interpretation of this proxy requires a detailed knowledge about processes that fractionate Cr on the Earth’s surface......, and the quantification the Cr isotope composition of major Cr fluxes into and out of ocean. This thesis adds to the current knowledge of the Cr isotope system and is divided into two studies. The focus of the first study was to determine what processes control the Cr isotopic compositionof river water and to quantify...

  7. The upper bound on the lowest mass halo

    Science.gov (United States)

    Jethwa, P.; Erkal, D.; Belokurov, V.

    2018-01-01

    We explore the connection between galaxies and dark matter haloes in the Milky Way (MW) and quantify the implications on properties of the dark matter particle and the phenomenology of low-mass galaxy formation. This is done through a probabilistic comparison of the luminosity function of MW dwarf satellite galaxies to models based on two suites of zoom-in simulations. One suite is dark-matter-only, while the other includes a disc component, therefore we can quantify the effect of the MW's baryonic disc on our results. We apply numerous stellar-mass-halo-mass (SMHM) relations allowing for multiple complexities: scatter, a characteristic break scale, and subhaloes which host no galaxy. In contrast to previous works, we push the model/data comparison to the faintest dwarfs by modelling observational incompleteness, allowing us to draw three new conclusions. First, we constrain the SMHM relation for 102 2.4 × 108 M⊙ (1σ). Secondly, by translating to a warm dark matter (WDM) cosmology, we bound the thermal relic mass mWDM > 2.9 keV at 95 per cent confidence, on a par with recent constraints from the Lyman-α forest. Lastly, we find that the observed number of ultra-faint MW dwarfs is in tension with the theoretical prediction that reionization prevents galaxy formation in almost all 108 M⊙ haloes. This can be tested with the next generation of deep imaging surveys. To this end, we predict the likely number of detectable satellite galaxies in the Subaru/Hyper Suprime-Cam survey and the Large Synoptic Survey Telescope. Confronting these predictions with future observations will be amongst our strongest tests of WDM and the effect reionization on low-mass systems.

  8. HaloTag as a reporter gene: positron emission tomography imaging with (64)Cu-labeled second generation HaloTag ligands.

    Science.gov (United States)

    Hong, Hao; Benink, Hélène A; Uyeda, H Tetsuo; Valdovinos, Hector F; Zhang, Yin; Meisenheimer, Poncho; Barnhart, Todd E; Fan, Frank; Cai, Weibo

    2013-01-01

    THE GOAL OF THIS STUDY IS TO EMPLOY THE HALOTAG TECHNOLOGY FOR POSITRON EMISSION TOMOGRAPHY (PET), WHICH INVOLVES TWO COMPONENTS: the HaloTag protein (a modified hydrolase which covalently binds to synthetic ligands) and HaloTag ligands (HTLs). 4T1 murine breast cancer cells were stably transfected to express HaloTag protein on the surface (termed as 4T1-HaloTag-ECS, ECS denotes extracellular surface). Two new HTLs were synthesized and termed NOTA-HTL2G-S and NOTA-HTL2G-L (2G indicates second generation, S stands for short, L stands for long, NOTA denotes 1,4,7-triazacyclononane-N,N'N''-triacetic acid). Microscopy studies confirmed surface expression of HaloTag in 4T1-HaloTag-ECS cells, which specifically bind NOTA-HTL2G-S/L. Uptake of (64)Cu-NOTA-HTL2G-L in 4T1-HaloTag-ECS tumors (4.3 ± 0.5, 4.1± 0.2, 4.0 ± 0.2, 2.3 ± 0.1, and 2.2 ± 0.1 %ID/g at 0.5, 3, 6, 18, and 24 h post-injection respectively; n = 4) was significantly higher than that in the 4T1 tumors (3.0 ± 0.3, 3.0± 0.1, 3.0 ± 0.2, 2.0 ± 0.4, and 2.4 ± 0.3 %ID/g at 0.5, 3, 6, 18, and 24 h post-injection respectively; n = 4) at early time points. In comparison, (64)Cu-NOTA-HTL2G-S did not demonstrate significant uptake in either 4T1-HaloTag-ECS or 4T1 tumors. Blocking studies and autoradiography of tumor lysates confirmed that (64)Cu-NOTA-HTL2G-L binds specifically to HaloTag protein in the 4T1-HaloTag-ECS tumors, corroborated by histology. HaloTag protein-specific targeting and PET imaging in vivo with (64)Cu-NOTA-HTL2G-L serves as a proof-of-principle for future non-invasive and sensitive tracking of HaloTag-transfected cells with PET, as well as many other studies of gene/protein/cell function in vivo.

  9. Gravitational lensing of wormholes in the galactic halo region

    Energy Technology Data Exchange (ETDEWEB)

    Kuhfittig, Peter K.F. [Milwaukee School of Engineering, Department of Mathematics, Milwaukee, WI (United States)

    2014-03-15

    A recent study by Rahaman et al. has shown that the galactic halo possesses the necessary properties for supporting traversable wormholes, based on two observational results, the Navarro-Frenk-White density profile and the observed flat rotation curves of galaxies. Using a method for calculating the deflection angle pioneered by V. Bozza, it is shown that the deflection angle diverges at the throat of the wormhole. The resulting photon sphere has a radius of about 0.40 ly. Given the dark-matter background, detection may be possible from past data using ordinary light. (orig.)

  10. Charge Radii and Neutron Correlations in Helium Halo Nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Papadimitriou, Georgios [ORNL; Kruppa, A. T. [Institute of Nuclear Research, Debrecen, Hungary; Michel, N. [University of Jyvaskyla; Nazarewicz, W. [University of Tennessee, Knoxville (UTK) & Oak Ridge National Laboratory (ORNL); Ploszajczak, M. [Grand Accelerateur National d' Ions Lourds (GANIL); Rotureau, J. [University of Arizona

    2011-01-01

    Within the complex-energy configuration interaction framework, we study correlations of valence neutrons to explain the behavior of charge radii in the neutron halo nuclei ^{6,8}He. We find that the experimentally observed decrease of the charge radius between ^{6}He and ^{8}He is caused by a subtle interplay between three effects: dineutron correlations, a spin-orbit contribution to the charge radius, and a core swelling effect. We demonstrate that two-neutron angular correlations in the 2^+}_{1} resonance of ^{6}He differ markedly from the ground-state correlations in ^{6,8}He.

  11. MD 2179: Scraping of off-momentum halo after injection

    CERN Document Server

    Garcia Morales, Hector; Patecki, Marcin; Wretborn, Sven Joel; CERN. Geneva. ATS Department

    2018-01-01

    In this MD, a beam scraping was performed using the momentum primary collimator in IR3 where dispersion is high. A second scraping was performed using a TCSG in IR7 where dispersion is almost negligible. In such a way, we aim to disentangle the contribution of off-momentum particles to halo population. These scrapings will provide useful information to better understand the usual off-momentum losses we see at the start of the ramp. The MD results would also be used to benchmark simulations of off-momentum beam losses in order to gain confidence in simulation models.

  12. Flows of Baryons through the Milky Way Halo

    Science.gov (United States)

    Fox, Andrew J.

    2017-07-01

    The Milky Way provides an ideal opportunity to study baryon flows in the circumgalactic medium of a star-forming spiral galaxy. High velocity clouds (HVCs) seen in UV absorption toward background AGN probe the multi-phase ionized gas in the Galactic CGM. In this talk new observations from the Cosmic Origins Spectrograph (COS) on Hubble will be presented, focusing on two Galactic regions: the biconical outflow from the Galactic Center, which drives gas into the Fermi Bubbles, and the Smith Cloud, an accreting HVC close to the Galactic disk showing clear signs of fragmentation. These observations allow us to constrain the rates of gas circulation in the Galactic halo.

  13. Study of galactic halo F(T,TG) wormhole solutions

    Science.gov (United States)

    Sharif, M.; Nazir, Kanwal

    In this paper, we investigate static spherically symmetric wormhole solutions with galactic halo region in the background of F(T,TG) gravity. Here, T represents torsion scalar and TG is teleparallel equivalent Gauss-Bonnet term. For this purpose, we consider a diagonal tetrad and two specific F(T,TG) models. We analyze the wormhole structure through shape function graphically for both models. We also investigate the behavior of null/weak energy conditions. Finally, we evaluate the equilibrium condition to check stability of the wormhole solutions. It is concluded that there exists physically viable wormhole solution only for the first model that turns out to be stable.

  14. Mass measurement of short-lived halo nuclides

    Energy Technology Data Exchange (ETDEWEB)

    Bachelet, C.; Audi, G.; Gaulard, C.; Guenaut, C.; Lunney, D.; De Saint Simon, M.; Thibault, C. [CSNSM-IN2P3-CNRS, Orsay (France); Herfurth, F. [GSI, Darmstadt (Germany)

    2005-09-01

    A direct mass measurement of the very-short-lived halo nuclide {sup 11}Li (T{sub 1/2}=8.7ms) has been performed with the transmission mass spectrometer MISTRAL. The preliminary result for the two-neutron separation energy is S{sub 2n}=376{+-}5 keV, improving the precision seven times with an increase of 20% compared to the previous value. In order to confirm this value, the mass excess of {sup 11}Be has also been measured, ME=20171{+-}4 keV, in good agreement with the previous value. (orig.)

  15. A search for massive compact halo objects in our galaxy

    Energy Technology Data Exchange (ETDEWEB)

    Alock, C.; Axelrod, T.; Cook, K.; Park, H. (Lawrence Livermore National Lab., CA (USA)); Griest, K.; Stubbs, C. (California Univ., Berkeley, CA (USA). Center for Particle Astrophysics); Freeman, K.; Peterson, B.; Quinn, P.; Rodgers, A. (Australian National Univ., Canberra (Australia). Mount Stromlo and Siding Spring Observatories); Bennett, D.P.

    1990-12-19

    MAssive Compact Halo Objects such as brown dwarfs, Jupiters, and black holes are prime candidates to comprise the dark halo of our galaxy. Paczynski noted that these objects (dubbed MACHOs) can be detected via gravitational microlensing of stars in the Magellanic Clouds with the caveat that only about one in 10{sup 6} stars will be lensed at any given time. Our group is currently involved in constructing a dedicated observing system at the Mount Stromlo Observatory in Australia. We will use a refurbished 1.27 meter telescope and an innovative two-color CCD camera with 3.4 {times} 10{sup 7} pixels to monitor 10{sup 6} {minus} 10{sup 7} stars in the Magellanic Clouds. During the first year of operation (1991--1992), we hope to detect (or rule out) objects in the mass range 0.001M{sub {circle dot}} {le} M {le} 0.1M{sub {circle dot}}, and after five years, we hope to have covered the range 10{sup {minus}6}M{sub {circle dot}} < M {approx lt} 100M{sub {circle dot}}. 4 refs.

  16. Halo Skeletal Fixation: Techniques of Application and Prevention of Complications.

    Science.gov (United States)

    Botte; Byrne; Abrams; Garfin

    1996-01-01

    The halo skeletal fixator provides the most rigid cervical immobilization of all orthoses. However, complications such as pin loosening and infection are common. Appreciation of local anatomy and adherence to established application guidelines should minimize pin-related problems. A relatively safe zone for anterior pin placement is located 1 cm above the orbital rim and superior to the lateral two thirds of the orbit. Posterior pin-site locations are less critical; positioning on the posterolateral aspect of the skull, diagonal to the contralateral anterior pins, is generally desirable. Pins should enter the skull perpendicular to the cortex, with the ring or crown sitting below the widest portion of the skull and passing about 1 cm above the helix of the ear. Pins are inserted at a torque of 8 in-lb and retightened once to 8 in-lb at 48 hours. A loose pin can be retightened to 8 in-lb if resistance is met; otherwise, a loose pin should be replaced at a nearby site. Superficially infected pins are managed with local pin care and oral antibiotics. Persistent or severe infections require pin replacement to a nearby site, parenteral antibiotic therapy, and incision and drainage as needed. In-ability to maintain acceptable cervical reduction with a halo fixator is an indication for alternative treatment, such as internal fixation or traction.

  17. Stellar haloes in massive early-type galaxies

    Science.gov (United States)

    Buitrago, F.

    2017-03-01

    The Hubble Ultra Deep Field (HUDF) opens up an unique window to witness galaxy assembly at all cosmic distances. Thanks to its extraordinary depth, it is a privileged tool to beat the cosmological dimming, which affects any extragalactic observations and has a very strong dependence with redshift (1 +z)^4. In particular, massive (M_{stellar}>5 × 10^{10} M_⊙) Early Type Galaxies (ETGs) are the most interesting candidates for these studies, as they must grow in an inside-out fashion developing an extended stellar envelope/halo that accounts for their remarkable size evolution (˜5 times larger in the nearby Universe than at z=2-3). To this end we have analysed the 6 most massive ETGs at z data reduction and the exhaustive treatment of the Point Spread Function (PSF), we are able to trace the galaxy surface brightness profiles up to the same levels as in the local Universe but this time at = 0.65 (31 mag arcsec^{-2} in all 8 HST bands, ˜ 29 mag arcsec^{-2} restframe or beyond 25 effective radii). This fact enables us to investigate the galactic outskirts or stellar haloes at a previously unexplored era, characterising their light and mass profiles, colors and for the first time the amount of mass in ongoing mergers.

  18. Evidence against cuspy dark matter haloes in large galaxies

    Science.gov (United States)

    Rodrigues, Davi C.; del Popolo, Antonino; Marra, Valerio; de Oliveira, Paulo L. C.

    2017-09-01

    We develop and apply new techniques to uncover systematic effects in galaxy rotation curves (RCs). Considering that an ideal dark matter (DM) profile should yield RCs that have no bias towards any particular radius, we find that the Burkert DM profile satisfies the test, while the Navarro-Frenk-While (NFW) profile is better at fitting the region between one and two disc scale lengths than the inner disc scale length region. Our sample indicates that this behaviour happens to more than 75 per cent of the galaxies fitted with an NFW halo. Also, this tendency is not weakened by considering large galaxies, for instance those with M* ≳ 1010 M⊙. Besides the tests on the homogeneity of the fits, we also use a sample of 62 galaxies of diverse types to test the quality of the overall fit of each galaxy, and to search for correlations with stellar mass, gas mass and the disc scale length. In particular, we find that only 13 galaxies are better fitted by the NFW halo, and that even for the galaxies with M* ≳ 1010 M⊙, the Burkert profile either fits as well as, or better than, the NFW profile. This result is relevant since different baryonic effects important for the smaller galaxies, like supernova feedback and dynamical friction from baryonic clumps, indicate that at such large stellar masses the NFW profile should be preferred over the Burkert profile. Hence, our results suggest either there is a new baryonic effect or a change to the DM physics is required.

  19. The phase-space structure of tidally stripped haloes

    Science.gov (United States)

    Drakos, Nicole E.; Taylor, James E.; Benson, Andrew J.

    2017-06-01

    We propose a new method for generating equilibrium models of spherical systems of collisionless particles that are finite in extent, but whose central regions resemble dark matter haloes from cosmological simulations. This method involves iteratively removing unbound particles from a Navarro-Frenk-White (NFW) profile truncated sharply at some radius. The resulting models are extremely stable, and thus provide a good starting point for N-body simulations of isolated haloes. We provide a code to generate such models for NFW and a variety of other common density profiles. We then develop an analytic approximation to this truncated distribution function. Our method proceeds by analogy with the King model, truncating and shifting the original distribution function of an infinitely extended NFW profile in energy space. We show that the density profiles of our models closely resemble the tidally truncated density profiles seen previously in studies of satellite evolution. Pursuing this analogy further with a series of simulations of tidal mass-loss, we find that our models provide a good approximation to the full distribution function of tidally stripped systems, thus allowing theoretically motivated phase-space calculations for such systems.

  20. Triple Halo Coil: Development and Comparison with Other TMS Coils

    Science.gov (United States)

    Rastogi, Priyam; Hadimani, Ravi; Jiles, David

    Transcranial Magnetic Stimulation (TMS) is a non-invasive stimulation technique that can be used for the treatment of various neurological disorders such as Parkinson's Disease, PTSD, TBI and anxiety by regulating synaptic activity. TMS is FDA approved for the treatment of major depressive disorder. There is a critical need to develop deep TMS coils that can stimulate deeper regions of the brain without excessively stimulating the cortex in order to provide an alternative to surgical methods. We have developed a novel multi-coil configuration called ``Triple Halo Coil'' (THC) that can stimulate deep brain regions. Investigation of induced electric and magnetic field in these regions have been achieved by computer modelling. Comparison of the results due to THC configuration have been conducted with other TMS coils such as ``Halo Coil'', circular coil and ``Figure of Eight'' coil. There was an improvement of more than 15 times in the strength of magnetic field, induced by THC configuration at 10 cm below the vertex of the head when compared with the ``Figure of Eight'' coil alone. Carver Charitable Trust.

  1. Interaction of cosmic rays with cold clouds in galactic haloes

    Science.gov (United States)

    Wiener, Joshua; Oh, S. Peng; Zweibel, Ellen G.

    2017-05-01

    We investigate the effects of cosmic ray (CR) dynamics on cold, dense clouds embedded in a hot, tenuous galactic halo. If the magnetic field does not increase too much inside the cloud, the local reduction in Alfvén speed imposes a bottleneck on CRs streaming out from the star-forming galactic disc. The bottleneck flattens the upstream CR gradient in the hot gas, implying that multiphase structure could have global effects on CR-driven winds. A large CR pressure gradient can also develop on the outward-facing edge of the cloud. This pressure gradient has two independent effects. The CRs push the cloud upwards, imparting it with momentum. On smaller scales, the CRs pressurize cold gas in the fronts, reducing its density, consistent with the low densities of cold gas inferred in recent Cosmic Origins Spectrograph (COS) observations of local L* galaxies. They also heat the material at the cloud edge, broadening the cloud-halo interface and causing an observable change in interface ionic abundances. Due to the much weaker temperature dependence of CR heating relative to thermal-conductive heating, CR mediated fronts have a higher ratio of low-to-high ions compared to conduction fronts, in better agreement with observations. We investigate these effects separately using 1D simulations and analytic techniques.

  2. HaloTag, a Platform Technology for Protein Analysis.

    Science.gov (United States)

    Urh, Marjeta; Rosenberg, Martin

    2012-01-01

    Understanding protein function and interaction is central to the elucidation of biological processes. Systematic analysis of protein interactions have shown that the eukaryotic proteome is highly interconnected and that biological function frequently depends on the orchestrated action of many proteins. Perturbation of these functions or interactions can lead to various disease states and pharmacologic intervention can result in corrective therapies. The fact that proteins rarely act in isolation, but rather comprise complex machines that stably and/or transiently interact with many different partners at different times, demands the need for robust tools that allow comprehensive global analyses of these events. Here we describe a powerful protein fusion technology, the HaloTag platform, and how it enables the study of many facets of protein biology by offering a broad choice of applications. We review the development of the key aspects of the technology and it's performance in both in vitro and in vivo applications. In particular, we focus on HaloTag's multifunctional utility in protein imaging, protein isolation and display, and in the study of protein complexes and interactions. We demonstrate it's potential to help elucidate important facets of proteomic biology across complex biological systems at the biochemical, cell-based and whole animal level.

  3. DAMA RESULTS: DARK MATTER IN THE GALACTIC HALO

    Directory of Open Access Journals (Sweden)

    R. Bernabei

    2013-12-01

    Full Text Available Experimental efforts and theoretical developmens support that most of the Universe is Dark and a large fraction of it should be made of relic particles; many possibilities are open on their nature and interaction types. In particular, the DAMA/LIBRA experiment at Gran Sasso Laboratory (sensitive mass: ~250 kg is mainly devoted to the investigation of Dark Matter (DM particles in the Galactic halo by exploiting the model independent DM annual modulation signature with higly radiopure Na I(Tl targets. DAMA/LIBRA is the succesor of the first generation DAMA/NaI (sensitive mass: ~100 kg; cumulatively the two experiments have released so far the results obtained by analyzing an exposure of 1.17 t yr, collected over 13 annual cycles. The data show a model independent evidence of the presence of DM particles in the galactic halo at 8.9σ confidence level (C.L.. Some of the already achieved results are shortly reminded, the last upgrade occurred at fall 2010 is mentioned and future perspectives are sumarized.

  4. The bias of weighted dark matter halos from peak theory

    CERN Document Server

    Verde, Licia; Simpson, Fergus; Alvarez-Gaume, Luis; Heavens, Alan; Matarrese, Sabino

    2014-01-01

    We give an analytical form for the weighted correlation function of peaks in a Gaussian random field. In a cosmological context, this approach strictly describes the formation bias and is the main result here. Nevertheless, we show its validity and applicability to the evolved cosmological density field and halo field, using Gaussian random field realisations and dark matter N-body numerical simulations. Using this result from peak theory we compute the bias of peaks (and dark matter halos) and show that it reproduces results from the simulations at the ${\\mathcal O}(10\\%)$ level. Our analytical formula for the bias predicts a scale-dependent bias with two characteristics: a broad band shape which, however, is most affected by the choice of weighting scheme and evolution bias, and a more robust, narrow feature localised at the BAO scale, an effect that is confirmed in simulations. This scale-dependent bias smooths the BAO feature but, conveniently, does not move it. We provide a simple analytic formula to des...

  5. Keck Spectroscopy of NGVS Sources: Milky Way Halo Star Kinematics

    Science.gov (United States)

    Zhang, Hao; Guhathakurta, Puragra; Peng, Eric W.; Toloba, Elisa; Next Generation Virgo Cluster Survey (NGVS) Collaboration

    2017-01-01

    We present a study of the kinematics of main sequence turnoff stars in the halo of the Milky Way based on Next Generation Virgo Cluster Survey photometry and Keck/DEIMOS spectroscopic follow-up. Specifically, we investigate the properties of the Virgo overdensity and Sagittarius stream Milky Way halo substructures in the foreground of the Virgo Cluster of galaxies. We use an inverse concentration (iC) parameter that characterizes the angular size of a source, which is defined by the magnitude difference measured by two different apertures for the same object. After combining this information as well as redshift measured from spectra into a Z vs iC plot, all of the objects are separated clearly into three categories: foreground Milky Way stars, Virgo globular clusters, and background galaxies. Most objects located in unexpected regions in the V_iC plot are subsequently rejected through a rigorous examination due to low spectral quality or bad imaging quality, indicating that our sample selection approach gives a very clean classification. We then select Sagittarius stream stars and Virgo overdensity stars out of the foreground star sample to characterize their distributions of spatial position, radial velocity and metallicity, from which we can probe deeper into the history of structure formation in the Milky Way Galaxy. This research was supported by NASA and the National Science Foundation. HZ has been sponsored by China Scholarship Council to carry out this research project at University of California, Santa Cruz.

  6. La abundancia de galaxias y halos de materia oscura en el universo CDM

    Science.gov (United States)

    Abadi, M. G.; Benítez-Llambay, A.; Ferrero, I.

    A long-standing puzzle of CDM cosmological model concerns to the different shape of the galaxy stellar mass function and the halo mass function on dwarf galaxy scales. Dwarf galaxies are much less numerous than halos massive enough to host them; suggesting a complex non-linear relation between the mass of a galaxy and the mass of its surrounding halo. Usually; this is reconciled by appealing to baryonic processes that can reduce the efficiency of galaxy formation in low-mass halos. Recent work applying the abundance matching technique require that virtually no dwarf galaxies form in halos with virial mass below . We use rotation curves of dwarf galaxies compiled from the literature to explore whether their total enclosed mass is consistent with these constraints. Almost one-half of the dwarfs in our sample are at odds with this restriction; they are in halos with masses substantially below . Using a cosmological simulation of the formation of the Local Group of galaxies we found that ram-pressure stripping against the cosmic web removes baryons from low-mass halos without appealing to feedback or reionization. This mechanism may help to explain the scarcity of dwarf galaxies compared with the numerous low-mass halos expected in CDM and the large diversity of star formation histories and morphologies characteristic of faint galaxies. FULL TEXT IN SPANISH

  7. 77 FR 47114 - Manufacturer of Controlled Substances; Notice of Application; Halo Pharmaceutical Inc.

    Science.gov (United States)

    2012-08-07

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF JUSTICE Drug Enforcement Administration Manufacturer of Controlled Substances; Notice of Application; Halo Pharmaceutical... that on July 6, 2012, Halo Pharmaceutical Inc., 30 North Jefferson Road, Whippany, New Jersey 07981...

  8. 78 FR 51210 - Manufacturer of Controlled Substances; Notice of Application; Halo Pharmaceutical, Inc.

    Science.gov (United States)

    2013-08-20

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF JUSTICE Drug Enforcement Administration Manufacturer of Controlled Substances; Notice of Application; Halo Pharmaceutical... that on July 8, 2013, Halo Pharmaceutical, Inc., 30 North Jefferson Road, Whippany, New Jersey 07981...

  9. Alignments of Dark Matter Halos with Large-scale Tidal Fields: Mass and Redshift Dependence

    Science.gov (United States)

    Chen, Sijie; Wang, Huiyuan; Mo, H. J.; Shi, Jingjing

    2016-07-01

    Large-scale tidal fields estimated directly from the distribution of dark matter halos are used to investigate how halo shapes and spin vectors are aligned with the cosmic web. The major, intermediate, and minor axes of halos are aligned with the corresponding tidal axes, and halo spin axes tend to be parallel with the intermediate axes and perpendicular to the major axes of the tidal field. The strengths of these alignments generally increase with halo mass and redshift, but the dependence is only on the peak height, ν \\equiv {δ }{{c}}/σ ({M}{{h}},z). The scaling relations of the alignment strengths with the value of ν indicate that the alignment strengths remain roughly constant when the structures within which the halos reside are still in a quasi-linear regime, but decreases as nonlinear evolution becomes more important. We also calculate the alignments in projection so that our results can be compared directly with observations. Finally, we investigate the alignments of tidal tensors on large scales, and use the results to understand alignments of halo pairs separated at various distances. Our results suggest that the coherent structure of the tidal field is the underlying reason for the alignments of halos and galaxies seen in numerical simulations and in observations.

  10. The f(Script R) halo mass function in the cosmic web

    Science.gov (United States)

    von Braun-Bates, F.; Winther, H. A.; Alonso, D.; Devriendt, J.

    2017-03-01

    An important indicator of modified gravity is the effect of the local environment on halo properties. This paper examines the influence of the local tidal structure on the halo mass function, the halo orientation, spin and the concentration-mass relation. We use the excursion set formalism to produce a halo mass function conditional on large-scale structure. Our simple model agrees well with simulations on large scales at which the density field is linear or weakly non-linear. Beyond this, our principal result is that f(Script R) does affect halo abundances, the halo spin parameter and the concentration-mass relationship in an environment-independent way, whereas we find no appreciable deviation from \\text{ΛCDM} for the mass function with fixed environment density, nor the alignment of the orientation and spin vectors of the halo to the eigenvectors of the local cosmic web. There is a general trend for greater deviation from \\text{ΛCDM} in underdense environments and for high-mass haloes, as expected from chameleon screening.

  11. Abort Options for Human Missions to Earth-Moon Halo Orbits

    Science.gov (United States)

    Jesick, Mark C.

    2013-01-01

    Abort trajectories are optimized for human halo orbit missions about the translunar libration point (L2), with an emphasis on the use of free return trajectories. Optimal transfers from outbound free returns to L2 halo orbits are numerically optimized in the four-body ephemeris model. Circumlunar free returns are used for direct transfers, and cislunar free returns are used in combination with lunar gravity assists to reduce propulsive requirements. Trends in orbit insertion cost and flight time are documented across the southern L2 halo family as a function of halo orbit position and free return flight time. It is determined that the maximum amplitude southern halo incurs the lowest orbit insertion cost for direct transfers but the maximum cost for lunar gravity assist transfers. The minimum amplitude halo is the most expensive destination for direct transfers but the least expensive for lunar gravity assist transfers. The on-orbit abort costs for three halos are computed as a function of abort time and return time. Finally, an architecture analysis is performed to determine launch and on-orbit vehicle requirements for halo orbit missions.

  12. On the shape of dark matter haloes from MultiDark Planck simulations

    Science.gov (United States)

    Vega-Ferrero, Jesús; Yepes, Gustavo; Gottlöber, Stefan

    2017-05-01

    The halo shape plays a central role in determining important observational properties of the haloes such as mass, concentration and lensing cross-sections. The triaxiality of lensing galaxy clusters has a substantial impact on the distribution of the largest Einstein radii, while weak lensing techniques are sensitive to the intrinsic halo ellipticity. In this work, we provide scaling relations for the shapes of dark matter haloes as a function of mass (peak height) and redshift over more than four orders of magnitude in halo masses, namely from 1011.5 to 1015.8 h-1 M⊙. We have analysed four dark matter only simulations from the MultiDark cosmological simulation suite with more than 56 billion particles within boxes of 4.0, 2.5, 1.0 and 0.4 h-1 Gpc size assuming Planck cosmology. The dark matter haloes have been identified in the simulations using the rockstar halo finder, which also determines the axis ratios in terms of the diagonalization of the inertia tensor. In order to infer the shape for a hypothetical halo of a given mass at a given redshift, we provide fitting functions to the minor-to-major and intermediate-to-major axis ratios as a function of the peak height.

  13. Halo statistics analysis within medium volume cosmological N-body simulation

    Directory of Open Access Journals (Sweden)

    Martinović N.

    2015-01-01

    Full Text Available In this paper we present halo statistics analysis of a ΛCDM N body cosmological simulation (from first halo formation until z = 0. We study mean major merger rate as a function of time, where for time we consider both per redshift and per Gyr dependence. For latter we find that it scales as the well known power law (1 + zn for which we obtain n = 2.4. The halo mass function and halo growth function are derived and compared both with analytical and empirical fits. We analyse halo growth through out entire simulation, making it possible to continuously monitor evolution of halo number density within given mass ranges. The halo formation redshift is studied exploring possibility for a new simple preliminary analysis during the simulation run. Visualization of the simulation is portrayed as well. At redshifts z = 0−7 halos from simulation have good statistics for further analysis especially in mass range of 1011 − 1014 M./h. [176021 ’Visible and invisible matter in nearby galaxies: theory and observations

  14. The build up of the correlation between halo spin and the large-scale structure

    Science.gov (United States)

    Wang, Peng; Kang, Xi

    2018-01-01

    Both simulations and observations have confirmed that the spin of haloes/galaxies is correlated with the large-scale structure (LSS) with a mass dependence such that the spin of low-mass haloes/galaxies tend to be parallel with the LSS, while that of massive haloes/galaxies tend to be perpendicular with the LSS. It is still unclear how this mass dependence is built up over time. We use N-body simulations to trace the evolution of the halo spin-LSS correlation and find that at early times the spin of all halo progenitors is parallel with the LSS. As time goes on, mass collapsing around massive halo is more isotropic, especially the recent mass accretion along the slowest collapsing direction is significant and it brings the halo spin to be perpendicular with the LSS. Adopting the fractional anisotropy (FA) parameter to describe the degree of anisotropy of the large-scale environment, we find that the spin-LSS correlation is a strong function of the environment such that a higher FA (more anisotropic environment) leads to an aligned signal, and a lower anisotropy leads to a misaligned signal. In general, our results show that the spin-LSS correlation is a combined consequence of mass flow and halo growth within the cosmic web. Our predicted environmental dependence between spin and large-scale structure can be further tested using galaxy surveys.

  15. Synthesis of organothioacrylonitriles and organoselenoacrylonitriles by reaction of 1-Halo-1-chalcogenoalkenes with CuCN

    Energy Technology Data Exchange (ETDEWEB)

    Silveira, Claudio C.; Caliari, Vinicius; Vieira, Adriano S.; Mendes, Samuel R. [Universidade Federal de Santa Maria (UFSM), RS (Brazil). Dept. de Quimica]. E-mail: silveira@quimica.ufsm.br

    2007-07-01

    Reaction of 1-halo-1-organothio or 1-halo-1-organoseleno alkenes with CuCN in NMP as solvent provides {alpha}-phenylthio or {alpha}-phenylseleno acrylonitriles in good yields. The reaction showed a low stereoselectivity and the products were obtained as E/Z mixtures of isomers. (author)

  16. Structure and substructure in the stellar halo of the Milky Way

    NARCIS (Netherlands)

    Pila Díez, Berenice

    2015-01-01

    In this thesis we present research on the stellar halo of our Galaxy. In particular we focus on measuring the shape and profile of the stellar halo through photometric techniques and main sequence turnoff point star counts. We also present a cross-correlation algorithm that can detect stellar

  17. 40 CFR 721.10063 - Halo substituted hydroxy nitrophenyl amide (generic).

    Science.gov (United States)

    2010-07-01

    ... amide (generic). 721.10063 Section 721.10063 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.10063 Halo substituted hydroxy nitrophenyl amide (generic). (a) Chemical... as halo substituted hydroxy nitrophenyl amide (PMN P-04-792) is subject to reporting under this...

  18. The mass function of unprocessed dark matter haloes and merger tree branching rates

    Science.gov (United States)

    Benson, Andrew J.

    2017-05-01

    A common approach in semi-analytic modelling of galaxy formation is to construct Monte Carlo realizations of merger histories of dark matter haloes whose masses are sampled from a halo mass function. Both the mass function itself and the merger rates used to construct merging histories are calibrated to N-body simulations. Typically, 'backsplash' haloes (those which were once subhaloes within a larger halo, but which have since moved outside of the halo) are counted in both the halo mass functions and in the merger rates (or, equivalently, progenitor mass functions). This leads to a double counting of mass in Monte Carlo merger histories, which will bias results relative to N-body results. We measure halo mass functions and merger rates with this double counting removed in a large, cosmological N-body simulation with cosmological parameters consistent with current constraints. Furthermore, we account for the inherently noisy nature of N-body halo mass estimates when fitting functions to N-body data, and show that ignoring these errors leads to a significant systematic bias given the precision statistics available from state-of-the-art N-body cosmological simulations.

  19. The shape of dark matter haloes in the Aquarius simulations : evolution and memory

    NARCIS (Netherlands)

    Vera-Ciro, Carlos A.; Sales, Laura V.; Helmi, Amina; Frenk, Carlos S.; Navarro, Julio F.; Springel, Volker; Vogelsberger, Mark; White, Simon D. M.

    We use the high-resolution cosmological N-body simulations from the Aquarius project to investigate in detail the mechanisms that determine the shape of Milky Way type dark matter haloes. We find that, when measured at the instantaneous virial radius, the shape of individual haloes changes with

  20. The kinematics of globular clusters systems in the outer halos of the Aquarius simulations

    NARCIS (Netherlands)

    Veljanoski, J.; Helmi, A.

    2016-01-01

    Stellar halos and globular cluster (GC) systems contain valuable information regarding the assembly history of their host galaxies. Motivated by the detection of a significant rotation signal in the outer halo GC system of M 31, we investigate the likelihood of detecting such a rotation signal in

  1. The shape of dark matter haloes in the Aquarius simulations : Evolution and memory

    NARCIS (Netherlands)

    Vera-Ciro, C.A.; Sales, L. V.; Helmi, A.; Reyle, C; Robin, A; Schultheis, M

    We use the high resolution cosmological N-body simulations from the Aquarius project to investigate in detail the mechanisms that determine the shape of Milky Way-type dark matter haloes. We find that, when measured at the instantaneous virial radius, the shape of individual haloes changes with

  2. The shape of dark matter haloes in the Aquarius simulations: Evolution and memory

    NARCIS (Netherlands)

    Vera-Ciro, C. A.; Sales, L. V.; Helmi, A.

    We use the high resolution cosmological N-body simulations from the Aquarius project to investigate in detail the mechanisms that determine the shape of Milky Way-type dark matter haloes. We find that, when measured at the instantaneous virial radius, the shape of individual haloes changes with

  3. The shape of dark matter haloes in the Aquarius simulations: Evolution and memory

    Directory of Open Access Journals (Sweden)

    Sales L.V.

    2012-02-01

    Full Text Available We use the high resolution cosmological N-body simulations from the Aquarius project to investigate in detail the mechanisms that determine the shape of Milky Way-type dark matter haloes. We find that, when measured at the instantaneous virial radius, the shape of individual haloes changes with time, evolving from a typically prolate configuration at early stages to a more triaxial/oblate geometry at the present day. This evolution in halo shape correlates well with the distribution of the infalling material: prolate configurations arise when haloes are fed through narrow filaments, which characterizes the early epochs of halo assembly, whereas triaxial/oblate configurations result as the accretion turns more isotropic at later times. Interestingly, at redshift z = 0, clear imprints of the past history of each halo are recorded in their shapes at different radii, which also exhibit a variation from prolate in the inner regions to triaxial/oblate in the outskirts. Provided that the Aquarius haloes are fair representatives of Milky Way-like 1012M☉ objects, we conclude that the shape of such dark matter haloes is a complex, time-dependent property, with each radial shell retaining memory of the conditions at the time of collapse.

  4. The Galaxy-Halo Connection in High-redshift Universe: Details and Evolution of Stellar-to-halo Mass Ratios of Lyman Break Galaxies on CFHTLS Deep Fields

    Science.gov (United States)

    Ishikawa, Shogo; Kashikawa, Nobunari; Toshikawa, Jun; Tanaka, Masayuki; Hamana, Takashi; Niino, Yuu; Ichikawa, Kohei; Uchiyama, Hisakazu

    2017-05-01

    We present the results of clustering analyses of Lyman break galaxies (LBGs) at z˜ 3, 4, and 5 using the final data release of the Canada-France-Hawaii Telescope Legacy Survey (CFHTLS). Deep- and wide-field images of the CFHTLS Deep Survey enable us to obtain sufficiently accurate two-point angular correlation functions to apply a halo occupation distribution analysis. The mean halo masses, calculated as ={10}11.7{--}{10}12.8 {h}-1 {M}⊙ , increase with the stellar-mass limit of LBGs. The threshold halo mass to have a central galaxy, {M}\\min , follows the same increasing trend as the low-z results, whereas the threshold halo mass to have a satellite galaxy, M 1, shows higher values at z=3{--}5 than z=0.5{--}1.5, over the entire stellar mass range. Satellite fractions of dropout galaxies, even at less massive halos, are found to drop sharply, from z = 2 down to less than 0.04, at z=3{--}5. These results suggest that satellite galaxies form inefficiently within dark halos at z=3{--}5, even for less massive satellites with {M}\\star pivot}, which is the halo mass at a peak in the star-formation efficiency, at 3 3. In addition, {M}{{h}}{pivot} and its normalization are found to be almost unchanged during 0< z< 5. Our study provides observational evidence that galaxy formation is ubiquitously most efficient near a halo mass of {M}{{h}}˜ {10}12 {M}⊙ over cosmic time.

  5. Sensitivity of the halo nuclei-12C elastic scattering at incident nucleon energy 800 MeV to the halo density distribution

    Science.gov (United States)

    Hassan, M. A. M.; Nour El-Din, M. S. M.; Ellithi, A.; Hosny, H.; Salama, T. N. E.

    2017-10-01

    In the framework of Glauber optical limit approximation where Coulomb effect is taken into account, the elastic scattering differential cross section for halo nuclei with {}^{12}{C} at 800 MeV/N has been calculated. Its sensitivity to the halo densities and the root mean square of the core and halo is the main goal of the current study. The projectile nuclei are taken to be one-neutron and two-neutron halo. The calculations are carried out for Gaussian-Gaussian, Gaussian-Oscillator and Gaussian-2 s phenomenological densities for each considered projectile in the mass number range 6-29. Also included a comparison between the obtained results of phenomenological densities and the results within the microscopic densities LSSM of {}6{He} and {}^{11}{Li} and microscopic densities GCM of {}^{11}{Be} where the density of the target nucleus {}^{12}{C} obtained from electron-{}^{12}{C} scattering is used. The zero range approximation is considered in the calculations. We found that the sensitivity of elastic scattering differential cross section to the halo density is clear if the nucleus appears as two clear different clusters, core and halo.

  6. Isobar analog states (IAS), double isobar analog states (DIAS), configuration states (CS), and double configuration states (DCS) in halo nuclei. Halo isomers

    Energy Technology Data Exchange (ETDEWEB)

    Izosimov, I. N., E-mail: izosimov@jinr.ru [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation)

    2015-10-15

    It has been shown that IAS, DIAS, CS, and DCS can simultaneously have n-n, n-p, and p-p halo components in their wave functions. Differences in halo structure of the excited and ground states can result in the formation of isomers (halo-isomers). Both the Borromean and tango halo types can be observed for n-p configurations of atomic nuclei. The structure of the ground and excited states with different isospin quantum number in halo like nuclei is discussed. B(Mλ) and B(Eλ) for γ-transitions in {sup 6,7,8}Li, {sup 8,9,10}Be, {sup 8,10,11}B, {sup 10,11,12,13,14}C, {sup 13,14,15,16,17}N, {sup 15,16,17,19}O, and {sup 17}F are analyzed. Special attention is given to nuclei whose ground state does not exhibit halo structure but the excited state may have one.

  7. The Splashback Radius of Halos from Particle Dynamics. I. The SPARTA Algorithm

    Science.gov (United States)

    Diemer, Benedikt

    2017-07-01

    Motivated by the recent proposal of the splashback radius as a physical boundary of dark-matter halos, we present a parallel computer code for Subhalo and PARticle Trajectory Analysis (Sparta). The code analyzes the orbits of all simulation particles in all host halos, billions of orbits in the case of typical cosmological N-body simulations. Within this general framework, we develop an algorithm that accurately extracts the location of the first apocenter of particles after infall into a halo, or splashback. We define the splashback radius of a halo as the smoothed average of the apocenter radii of individual particles. This definition allows us to reliably measure the splashback radii of 95% of host halos above a resolution limit of 1000 particles. We show that, on average, the splashback radius and mass are converged to better than 5% accuracy with respect to mass resolution, snapshot spacing, and all free parameters of the method.

  8. Transverse Beam Halo Measurements at High Intensity Neutrino Source (HINS) using Vibrating Wire Monitor

    Energy Technology Data Exchange (ETDEWEB)

    Chung, M.; Hanna, B.; Scarpine, V.; Shiltsev, V.; Steimel, J.; Artinian, S.; Arutunian, S.

    2015-02-26

    The measurement and control of beam halos will be critical for the applications of future high-intensity hadron linacs. In particular, beam profile monitors require a very high dynamic range when used for the transverse beam halo measurements. In this study, the Vibrating Wire Monitor (VWM) with aperture 60 mm was installed at the High Intensity Neutrino Source (HINS) front-end to measure the transverse beam halo. A vibrating wire is excited at its resonance frequency with the help of a magnetic feedback loop, and the vibrating and sensitive wires are connected through a balanced arm. The sensitive wire is moved into the beam halo region by a stepper motor controlled translational stage. We study the feasibility of the vibrating wire for the transverse beam halo measurements in the low-energy front-end of the proton linac.

  9. HaloTag protein-mediated specific labeling of living cells with quantum dots.

    Science.gov (United States)

    So, Min-kyung; Yao, Hequan; Rao, Jianghong

    2008-09-26

    Quantum dots emerge as an attractive alternative to small molecule fluorophores as fluorescent tags for in vivo cell labeling and imaging. This communication presents a method for specific labeling of live cells using quantum dots. The labeling is mediated by HaloTag protein expressed at the cell surface which forms a stable covalent adduct with its ligand (HaloTag ligand). The labeling can be performed in one single step with quantum dot conjugates that are functionalized with HaloTag ligand, or in two steps with biotinylated HaloTag ligand first and followed by streptavidin coated quantum dots. Live cell fluorescence imaging indicates that the labeling is specific and takes place at the cell surface. This HaloTag protein-mediated cell labeling method should facilitate the application of quantum dots for live cell imaging.

  10. Direct observations of the formation of the solar wind halo from the strahl

    Energy Technology Data Exchange (ETDEWEB)

    Gurgiolo, C. [Bitterroot Basic Research, Hamilton, MT (United States); Goldstein, M.L.; Vinas, A.F. [NASA Goddard Space Flight Center, Greenbelt, MD (United States). Geospace Science Lab.; Fazakerley, A.N. [Univ. College London, Holmbury St. Mary Dorking, Surrey (United Kingdom). Mullard Space Science Lab.

    2012-07-01

    Observations of a continual erosion of the strahl and build up of the halo with distance from the sun suggests that, at least in part, the halo may be formed as a result of scattering of the strahl. This hypothesis is supported in this paper by observation of intense scattering of strahl electrons, which gives rise to a proto-halo electron population. This population eventually merges into, or becomes the halo. The fact that observations of intense scattering of the strahl are not common implies that the formation of the halo may not be a continuous process, but one that occurs, in part, in bursts in regions where the conditions responsible for the scattering are optimum. (orig.)

  11. Halo Emission of the Cat's Eye Nebula, NGC 6543 Shock Excitation by Fast Stellar Winds

    Directory of Open Access Journals (Sweden)

    Siek Hyung

    2002-09-01

    Full Text Available Images taken with the Chandra X-ray telescope have for the the first time revealed the central, wind-driven, hot bubble (Chu et al. 2001, while Hubble Space Telescope (HST WFPC2 images of the Cat's Eye nebula, NGC 6543, show that the temperature of the halo region of angular radius ~ 20'', is much higher than that of the inner bright H II region. With the coupling of a photoionization calculation to a hydrodynamic simulation, we predict the observed [O III] line intensities of the halo region with the same O abundance as in the core H II region: oxygen abundance gradient does not appear to exist in the NGC 6543 inner halo. An interaction between a (leaky fast stellar wind and halo gas may cause the higher excitation temperatures in the halo region and the inner hot bubble region observed with the Chandra X-ray telescope.

  12. Halo Models of Large Scale Structure and Reliability of Cosmological N-Body Simulations

    Directory of Open Access Journals (Sweden)

    José Gaite

    2013-05-01

    Full Text Available Halo models of the large scale structure of the Universe are critically examined, focusing on the definition of halos as smooth distributions of cold dark matter. This definition is essentially based on the results of cosmological N-body simulations. By a careful analysis of the standard assumptions of halo models and N-body simulations and by taking into account previous studies of self-similarity of the cosmic web structure, we conclude that N-body cosmological simulations are not fully reliable in the range of scales where halos appear. Therefore, to have a consistent definition of halos is necessary either to define them as entities of arbitrary size with a grainy rather than smooth structure or to define their size in terms of small-scale baryonic physics.

  13. Mg II Absorbers: Metallicity Evolution and Cloud Morphology

    Science.gov (United States)

    Lan, Ting-Wen; Fukugita, Masataka

    2017-12-01

    Metal abundance and its evolution are studied for Mg II quasar absorption line systems from their weak, unsaturated spectral lines using stacked spectra from the archived data of the Sloan Digital Sky Survey. They show an abundance pattern that resembles that of the Galactic halo or Small Magellanic Cloud, with metallicity [Z/H] showing an evolution from redshift z = 2 to 0.5: metallicity becomes approximately solar or even larger at z≈ 0. We show that the evolution of the metal abundance traces the cumulative amount of the hydrogen fuel consumed in star formation in galaxies. With the aid of a spectroscopic simulation code, we infer the median gas density of the cloud to be roughly 0.3 {{cm}}-3, with which the elemental abundance in various ionization stages, in particular C I, is consistently explained. This gas density implies that the size of the Mg II clouds is of the order of 0.03 kpc, which suggests that individual Mg II clouds around a galaxy are of a baryonic mass typically {10}3 {M}⊙ . This means that Mg II clouds are numerous and “foamy,” rather than a large entity that covers a sizable fraction of galaxies with a single cloud.

  14. What Makes the Family of Barred Disc Galaxies So Rich: Damping Stellar Bars in Spinning Haloes

    Science.gov (United States)

    Collier, Angela; Shlosman, Isaac; Heller, Clayton

    2018-02-01

    We model and analyze the secular evolution of stellar bars in spinning dark matter (DM) haloes with the cosmological spin λ ˜ 0 - 0.09. Using high-resolution stellar and DM numerical simulations, we focus on angular momentum exchange between stellar discs and DM haloes of various axisymmetric shapes — spherical, oblate and prolate. We find that stellar bars experience a diverse evolution which is guided by the ability of parent haloes to absorb angular momentum, J, lost by the disc through the action of gravitational torques, resonant and non-resonant. We confirm that dynamical bar instability is accelerated via resonant J-transfer to the halo. Our main findings relate to the long-term, secular evolution of disc-halo systems: with an increasing λ, bars experience less growth and basically dissolve after they pass through vertical buckling instability. Specifically, with increasing λ, (1) The vertical buckling instability in stellar bars colludes with inability of the inner halo to absorb J — this emerges as the main factor weakening or destroying bars in spinning haloes; (2) Bars lose progressively less J, and their pattern speeds level off; (3) Bars are smaller, and for λ ≳ 0.06 cease their growth completely following buckling; (4) Bars in λ > 0.03 halos have ratio of corotation-to-bar radii, RCR/Rb > 2, and represent so-called slow bars without offset dust lanes. We provide a quantitative analysis of J-transfer in disc-halo systems, and explain the reasons for absence of growth in fast spinning haloes and its observational corollaries. We conclude that stellar bar evolution is substantially more complex than anticipated, and bars are not as resilient as has been considered so far.

  15. Pushing down the low-mass halo concentration frontier with the Lomonosov cosmological simulations

    Science.gov (United States)

    Pilipenko, Sergey V.; Sánchez-Conde, Miguel A.; Prada, Francisco; Yepes, Gustavo

    2017-12-01

    We introduce the Lomonosov suite of high-resolution N-body cosmological simulations covering a full box of size 32 h-1 Mpc with low-mass resolution particles (2 × 107 h-1 M⊙) and three zoom-in simulations of overdense, underdense and mean density regions at much higher particle resolution (4 × 104 h-1 M⊙). The main purpose of this simulation suite is to extend the concentration-mass relation of dark matter haloes down to masses below those typically available in large cosmological simulations. The three different density regions available at higher resolution provide a better understanding of the effect of the local environment on halo concentration, known to be potentially important for small simulation boxes and small halo masses. Yet, we find the correction to be small in comparison with the scatter of halo concentrations. We conclude that zoom simulations, despite their limited representativity of the volume of the Universe, can be effectively used for the measurement of halo concentrations at least at the halo masses probed by our simulations. In any case, after a precise characterization of this effect, we develop a robust technique to extrapolate the concentration values found in zoom simulations to larger volumes with greater accuracy. Altogether, Lomonosov provides a measure of the concentration-mass relation in the halo mass range 107-1010 h-1 M⊙ with superb halo statistics. This work represents a first important step to measure halo concentrations at intermediate, yet vastly unexplored halo mass scales, down to the smallest ones. All Lomonosov data and files are public for community's use.

  16. Mergers and mass accretion for infalling halos both end well outside cluster virial radii

    Energy Technology Data Exchange (ETDEWEB)

    Behroozi, Peter S.; Wechsler, Risa H.; Lu, Yu; Hahn, Oliver; Busha, Michael T.; Klypin, Anatoly; Primack, Joel R.

    2014-05-14

    We find that infalling dark matter halos (i.e., the progenitors of satellite halos) begin losing mass well outside the virial radius of their eventual host halos. The peak mass occurs at a range of clustercentric distances, with median and 68th percentile range of $1.8^{+2.3}_{-1.0} \\,R_\\mathrm{vir,host}$ for progenitors of z = 0 satellites. The peak circular velocity for infalling halos occurs at significantly larger distances ($3.7^{+3.3}_{-2.2} \\,R_\\mathrm{vir,host}$ at z = 0). This difference arises because different physical processes set peak circular velocity (typically, ~1:5 and larger mergers which cause transient circular velocity spikes) and peak mass (typically, smooth accretion) for infalling halos. We find that infalling halos also stop having significant mergers well before they enter the virial radius of their eventual hosts. Mergers larger than a 1:40 ratio in halo mass end for infalling halos at similar clustercentric distances (~1.9 R vir, host) as the end of overall mass accretion. However, mergers larger than 1:3 typically end for infalling halos at more than four virial radial away from their eventual hosts. This limits the ability of mergers to affect quenching and morphology changes in clusters. We also note that the transient spikes which set peak circular velocity may lead to issues with abundance matching on that parameter, including unphysical galaxy stellar mass growth profiles near clusters; we propose a simple observational test to check if a better halo proxy for galaxy stellar mass exists.

  17. ZOMG - II. Does the halo assembly history influence central galaxies and gas accretion?

    Science.gov (United States)

    Romano-Díaz, Emilio; Garaldi, Enrico; Borzyszkowski, Mikolaj; Porciani, Cristiano

    2017-08-01

    The growth rate and the internal dynamics of galaxy-sized dark-matter haloes depend on their location within the cosmic web. Haloes that sit at the nodes grow in mass till the present time and are dominated by radial orbits. Conversely, haloes embedded in prominent filaments do not change much in size and are dominated by tangential orbits. Using zoom hydrodynamical simulations including star formation and feedback, we study how gas accretes on to these different classes of objects, which, for simplicity, we dub 'accreting' and 'stalled' haloes. We find that all haloes get a fresh supply of newly accreted gas in their inner regions, although this slowly decreases with time, in particular for the stalled haloes. The inflow of new gas is always higher than (but comparable with) that of recycled material. Overall, the cold-gas fraction increases (decreases) with time for the accreting (stalled) haloes. In all cases, a stellar disc and a bulge form at the centre of the simulated haloes. The total stellar mass is in excellent agreement with expectations based on the abundance-matching technique. Many properties of the central galaxies do not seem to correlate with the large-scale environment in which the haloes reside. However, there are two notable exceptions that characterize stalled haloes with respect to their accreting counterparts: (I) The galaxy disc contains much older stellar populations. (II) Its vertical scaleheight is larger by a factor of 2 or more. This thickening is likely due to the heating of the long-lived discs by mergers and close flybys.

  18. Discovery of the Indium Isotopes

    CERN Document Server

    Amos, S

    2010-01-01

    Thirty-eight indium isotopes (A = 98-135) have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  19. Calculation of nucleon densities in calcium, nickel, and molybdenum isotopes on the basis of the dispersive optical model

    Science.gov (United States)

    Bespalova, O. V.; Klimochkina, A. A.

    2017-09-01

    The radial distributions of proton and neutron densities in the even-even isotopes 40-70Ca and 48-78Ni and the analogous distributions of neutron densities in the even-even isotopes 92-138Mo were calculated on the basis of the mean-fieldmodel involving a dispersive optical potential. The respective root-mean-square radii and neutron-skin thicknesses were determined for the nuclei under study. In N > 40 calcium isotopes, the calculated neutron root-mean-square radius exhibits a fast growth with increasing N, and this is consistent with the prediction of the neutron-halo structure in calcium isotopes near the neutron drip line.

  20. Towards reconstructing ancient seawater Mg/Ca by combining porcelaneous and hyaline foraminiferal Mg/Ca-temperature calibrations

    Science.gov (United States)

    Wit, J. C.; de Nooijer, L. J.; Haig, J.; Jorissen, F. J.; Thomas, E.; Reichart, G.-J.

    2017-08-01

    The temperature of the deep ocean plays a vital role in the Earth's climate system. Paleo-reconstructions of deep-sea temperatures have traditionally been based on the oxygen isotope composition of deep-sea benthic foraminiferal calcite shells, although this parameter depends upon polar ice volume as well as temperature. More recent reconstructions use Mg/Ca in these shells, with temperature calibrations based on empirical relationships observed in present-day oceans. Incorporation of Mg (DMg) into foraminiferal calcite is, however, not solely dependent on temperature, but also on seawater Mg/Ca. Due to its long oceanic residence time, Mg concentrations remained relatively constant over time scales of a few hundred thousand years, but varied significantly over longer geological time scales. Accurate reconstruction of past temperatures using foraminiferal Mg/Ca, therefore, hinges on our understanding of Mg/Ca seawater changes on geological timescales. We explore a novel, independent approach to reconstructing past seawater Mg/Ca using the temperature-dependent offset in DMg between porcelaneous (secreting intermediate- or high-Mg calcite, abbreviated as IMC or HMC, respectively) and hyaline (producing low-Mg calcite, abbreviated as LMC) benthic foraminifera. We calibrated the Mg/Ca-temperature dependence for Pyrgo spp. (one of the few common, large-sized porcelaneous taxa present in the deep-sea since the middle Miocene), and combined this with an existing calibration of hyaline Cibicidoides spp. to mathematically solve for changes in Mg/Ca seawater through time. We show that changes in Mg/Ca seawater can be reconstructed using the offset between porcelaneous and hyaline foraminifera, but absolute values are highly dependent on the species-specific offset between Mg/Ca seawater and Mg-partition coefficients.

  1. SHELL ISOTOPE GEOCHEMISTRY

    African Journals Online (AJOL)

    Valley. Although fossil specimens of this subspecies have been used in palaeoclimatic reconstruction, there have been no previous reports of living examples. Here We describe the local habitat, climate and some aspects of ecology and isotopic variation within the snail shell. If isotope data can be obtained for fossil shells, ...

  2. ICT: isotope correction toolbox.

    Science.gov (United States)

    Jungreuthmayer, Christian; Neubauer, Stefan; Mairinger, Teresa; Zanghellini, Jürgen; Hann, Stephan

    2016-01-01

    Isotope tracer experiments are an invaluable technique to analyze and study the metabolism of biological systems. However, isotope labeling experiments are often affected by naturally abundant isotopes especially in cases where mass spectrometric methods make use of derivatization. The correction of these additive interferences--in particular for complex isotopic systems--is numerically challenging and still an emerging field of research. When positional information is generated via collision-induced dissociation, even more complex calculations for isotopic interference correction are necessary. So far, no freely available tools can handle tandem mass spectrometry data. We present isotope correction toolbox, a program that corrects tandem mass isotopomer data from tandem mass spectrometry experiments. Isotope correction toolbox is written in the multi-platform programming language Perl and, therefore, can be used on all commonly available computer platforms. Source code and documentation can be freely obtained under the Artistic License or the GNU General Public License from: https://github.com/jungreuc/isotope_correction_toolbox/ {christian.jungreuthmayer@boku.ac.at,juergen.zanghellini@boku.ac.at} Supplementary data are available at Bioinformatics online. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  3. Influence of entrance channel on the production of hassium isotopes

    Science.gov (United States)

    Hong, Juhee; Adamian, G. G.; Antonenko, N. V.

    2015-07-01

    The production of hassium isotopes Hs-271266 in various reactions 22Ne+249Cf,Mg,2625+248Cm,30Si+244Pu,S,3634+238U,40Ar+232Th , and 48Ca+226Ra is studied within the dinuclear system model. The experimental excitation functions of the isotopes 266 -271Hs are well described and predictions are made for future experiments.

  4. Electromagnetic properties of the Beryllium-11 nucleus in Halo EFT

    Directory of Open Access Journals (Sweden)

    Hammer H.-W.

    2010-04-01

    Full Text Available We compute electromagnetic properties of the Beryllium-11 nucleus using an effective field theory that exploits the separation of scales in this halo system. We fix the parameters of the EFT from measured data on levels and scattering lengths in the 10Be plus neutron system. We then obtain predictions for the B(E1 strength of the 1/2+ to 1/2− transition in the 11Be nucleus. We also compute the charge radius of the ground state of 11Be. Agreement with experiment within the expected accuracy of a leading-order computation in this EFT is obtained. We also indicate how higher-order corrections that affect both s-wave and p-wave 10 Be-neutron interactions will affect our results.

  5. Disentangling the Galactic Halo with APOGEE. II. Chemical and Star Formation Histories for the Two Distinct Populations

    Science.gov (United States)

    Fernández-Alvar, Emma; Carigi, Leticia; Schuster, William J.; Hayes, Christian R.; Ávila-Vergara, Nancy; Majewski, Steve R.; Allende Prieto, Carlos; Beers, Timothy C.; Sánchez, Sebastián F.; Zamora, Olga; García-Hernández, Domingo Aníbal; Tang, Baitian; Fernández-Trincado, José G.; Tissera, Patricia; Geisler, Douglas; Villanova, Sandro

    2018-01-01

    The formation processes that led to the current Galactic stellar halo are still under debate. Previous studies have provided evidence for different stellar populations in terms of elemental abundances and kinematics, pointing to different chemical and star formation histories (SFHs). In the present work, we explore, over a broader range in metallicity (-2.2Experiment (APOGEE). We aim to infer signatures of the initial mass function (IMF) and the SFH from the two α-to-iron versus iron abundance chemical trends for the most APOGEE-reliable α-elements (O, Mg, Si, and Ca). Using simple chemical-evolution models, we infer the upper mass limit (M up) for the IMF and the star formation rate, and its duration for each population. Compared with the low-α population, we obtain a more intense and longer-lived SFH, and a top-heavier IMF for the high-α population.

  6. Ice crystal characterization in cirrus clouds: a sun-tracking camera system and automated detection algorithm for halo displays

    Directory of Open Access Journals (Sweden)

    L. Forster

    2017-07-01

    Full Text Available Halo displays in the sky contain valuable information about ice crystal shape and orientation: e.g., the 22° halo is produced by randomly oriented hexagonal prisms while parhelia (sundogs indicate oriented plates. HaloCam, a novel sun-tracking camera system for the automated observation of halo displays is presented. An initial visual evaluation of the frequency of halo displays for the ACCEPT (Analysis of the Composition of Clouds with Extended Polarization Techniques field campaign from October to mid-November 2014 showed that sundogs were observed more often than 22° halos. Thus, the majority of halo displays was produced by oriented ice crystals. During the campaign about 27 % of the cirrus clouds produced 22° halos, sundogs or upper tangent arcs. To evaluate the HaloCam observations collected from regular measurements in Munich between January 2014 and June 2016, an automated detection algorithm for 22° halos was developed, which can be extended to other halo types as well. This algorithm detected 22° halos about 2 % of the time for this dataset. The frequency of cirrus clouds during this time period was estimated by co-located ceilometer measurements using temperature thresholds of the cloud base. About 25 % of the detected cirrus clouds occurred together with a 22° halo, which implies that these clouds contained a certain fraction of smooth, hexagonal ice crystals. HaloCam observations complemented by radiative transfer simulations and measurements of aerosol and cirrus cloud optical thickness (AOT and COT provide a possibility to retrieve more detailed information about ice crystal roughness. This paper demonstrates the feasibility of a completely automated method to collect and evaluate a long-term database of halo observations and shows the potential to characterize ice crystal properties.

  7. Predicting weak lensing statistics from halo mass reconstructions - Final Paper

    Energy Technology Data Exchange (ETDEWEB)

    Everett, Spencer [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-08-20

    As dark matter does not absorb or emit light, its distribution in the universe must be inferred through indirect effects such as the gravitational lensing of distant galaxies. While most sources are only weakly lensed, the systematic alignment of background galaxies around a foreground lens can constrain the mass of the lens which is largely in the form of dark matter. In this paper, I have implemented a framework to reconstruct all of the mass along lines of sight using a best-case dark matter halo model in which the halo mass is known. This framework is then used to make predictions of the weak lensing of 3,240 generated source galaxies through a 324 arcmin² field of the Millennium Simulation. The lensed source ellipticities are characterized by the ellipticity-ellipticity and galaxy-mass correlation functions and compared to the same statistic for the intrinsic and ray-traced ellipticities. In the ellipticity-ellipticity correlation function, I and that the framework systematically under predicts the shear power by an average factor of 2.2 and fails to capture correlation from dark matter structure at scales larger than 1 arcminute. The model predicted galaxy-mass correlation function is in agreement with the ray-traced statistic from scales 0.2 to 0.7 arcminutes, but systematically underpredicts shear power at scales larger than 0.7 arcminutes by an average factor of 1.2. Optimization of the framework code has reduced the mean CPU time per lensing prediction by 70% to 24 ± 5 ms. Physical and computational shortcomings of the framework are discussed, as well as potential improvements for upcoming work.

  8. Beam halo in high-intensity hadron linacs

    Energy Technology Data Exchange (ETDEWEB)

    Gerigk, F.

    2006-12-21

    This document aims to cover the most relevant mechanisms for the development of beam halo in high-intensity hadron linacs. The introduction outlines the various applications of high-intensity linacs and it will explain why, in the case of the CERN Superconducting Proton Linac (SPL) study a linac was chosen to provide a high-power beam, rather than a different kind of accelerator. The basic equations, needed for the understanding of halo development are derived and employed to study the effects of initial and distributed mismatch on high-current beams. The basic concepts of the particle-core model, envelope modes, parametric resonances, the free-energy approach, and the idea of core-core resonances are introduced and extended to study beams in realistic linac lattices. The approach taken is to study the behavior of beams not only in simplified theoretical focusing structures but to highlight the beam dynamics in realistic accelerators. All effects which are described and derived with simplified analytic models, are tested in realistic lattices and are thus related to observable effects in linear accelerators. This approach involves the use of high-performance particle tracking codes, which are needed to simulate the behavior of the outermost particles in distributions of up to 100 million macro particles. In the end a set of design rules are established and their impact on the design of a typical high-intensity machine, the CERN SPL, is shown. The examples given in this document refer to two different design evolutions of the SPL study: the first conceptual design report (SPL I) and the second conceptual design report (SPL II). (orig.)

  9. On the Evolution of Dark Matter Halo Properties Following Major and Minor Mergers

    Science.gov (United States)

    Wu, Peter; Zhang, Shawn; Lee, Christoph; Primack, Joel

    2018-01-01

    We conducted an analysis on dark matter halo properties following major and minor mergers to advance our understanding of halo evolution. In this work, we analyzed ~80,000 dark matter halos from the Bolshoi-Planck cosmological simulation and studied halo evolution during relaxation after major mergers. We then applied a Gaussian filter to the property evolutions and characterized peak distributions, frequencies, and variabilities for several halo properties, including centering, spin, shape (prolateness), scale radius, and virial ratio. However, there were also halos that experienced relaxation without the presence of major mergers. We hypothesized that this was due to minor mergers unrecorded by the simulation analysis. By using property peaks to create a novel merger detection algorithm, we attempted to find minor mergers and match them to the unaccounted relaxed halos. Not only did we find evidence that minor mergers were the causes, but we also found similarities between major and minor merger effects, showing the significance of minor mergers for future studies. Through our dark matter merger statistics, we expect our work to ultimately serve as vital parameters towards better understanding galaxy formation and evolution. Most of this work was carried out by high school students working under the auspices of the Science Internship Program (SIP) at UC Santa Cruz.

  10. Relation between halo spin and cosmic-web filaments at z ≃ 3

    Science.gov (United States)

    González, Roberto E.; Prieto, Joaquin; Padilla, Nelson; Jimenez, Raul

    2017-02-01

    We investigate the spin evolution of dark matter haloes and their dependence on the number of connected filaments from the cosmic web at high redshift (spin-filament relation hereafter). To this purpose, we have simulated 5000 haloes in the mass range 5 × 109 h-1 M⊙ to 5 × 1011 h-1 M⊙ at z = 3 in cosmological N-body simulations. We confirm the relation found by Prieto et al. (2015) where haloes with fewer filaments have larger spin. We also found that this relation is more significant for higher halo masses, and for haloes with a passive (no major mergers) assembly history. Another finding is that haloes with larger spin or with fewer filaments have their filaments more perpendicularly aligned with the spin vector. Our results point to a picture in which the initial spin of haloes is well described by tidal torque theory and then gets subsequently modified in a predictable way because of the topology of the cosmic web, which in turn is given by the currently favoured Lambda cold dark matter (LCDM) model. Our spin-filament relation is a prediction from LCDM that could be tested with observations.

  11. The HaloTag: Improving Soluble Expression and Applications in Protein Functional Analysis.

    Science.gov (United States)

    N Peterson, Scott; Kwon, Keehwan

    2012-01-01

    Technological and methodological advances have been critical for the rapidly evolving field of proteomics. The development of fusion tag systems is essential for purification and analysis of recombinant proteins. The HaloTag is a 34 KDa monomeric protein derived from a bacterial haloalkane dehalogenase. The majority of fusion tags in use today utilize a reversible binding interaction with a specific ligand. The HaloTag system is unique in that it forms a covalent linkage to its chloroalkane ligand. This linkage permits attachment of the HaloTag to a variety of functional reporters, which can be used to label and immobilize recombinant proteins. The success rate for HaloTag expression of soluble proteins is very high and comparable to maltose binding protein (MBP) tag. Furthermore, cleavage of the HaloTag does not result in protein insolubility that often is observed with the MBP tag. In the present report, we describe applications of the HaloTag system in our ongoing investigation of protein-protein interactions of the Y. pestis Type 3 secretion system on a custom protein microarray. We also describe the utilization of affinity purification/mass spectroscopy (AP/MS) to evaluate the utility of the Halo Tag system to characterize DNA binding activity and protein specificity.

  12. High Angular Momentum Halo Gas: A Feedback and Code-independent Prediction of LCDM

    Science.gov (United States)

    Stewart, Kyle R.; Maller, Ariyeh H.; Oñorbe, Jose; Bullock, James S.; Joung, M. Ryan; Devriendt, Julien; Ceverino, Daniel; Kereš, Dušan; Hopkins, Philip F.; Faucher-Giguère, Claude-André

    2017-07-01

    We investigate angular momentum acquisition in Milky Way-sized galaxies by comparing five high resolution zoom-in simulations, each implementing identical cosmological initial conditions but utilizing different hydrodynamic codes: Enzo, Art, Ramses, Arepo, and Gizmo-PSPH. Each code implements a distinct set of feedback and star formation prescriptions. We find that while many galaxy and halo properties vary between the different codes (and feedback prescriptions), there is qualitative agreement on the process of angular momentum acquisition in the galaxy’s halo. In all simulations, cold filamentary gas accretion to the halo results in ˜4 times more specific angular momentum in cold halo gas (λ cold ≳ 0.1) than in the dark matter halo. At z > 1, this inflow takes the form of inspiraling cold streams that are co-directional in the halo of the galaxy and are fueled, aligned, and kinematically connected to filamentary gas infall along the cosmic web. Due to the qualitative agreement among disparate simulations, we conclude that the buildup of high angular momentum halo gas and the presence of these inspiraling cold streams are robust predictions of Lambda Cold Dark Matter galaxy formation, though the detailed morphology of these streams is significantly less certain. A growing body of observational evidence suggests that this process is borne out in the real universe.

  13. High Angular Momentum Halo Gas: A Feedback and Code-independent Prediction of LCDM

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, Kyle R. [Department of Mathematical Sciences, California Baptist University, 8432 Magnolia Ave., Riverside, CA 92504 (United States); Maller, Ariyeh H. [Department of Physics, New York City College of Technology, 300 Jay St., Brooklyn, NY 11201 (United States); Oñorbe, Jose [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Bullock, James S. [Center for Cosmology, Department of Physics and Astronomy, The University of California at Irvine, Irvine, CA 92697 (United States); Joung, M. Ryan [Department of Astronomy, Columbia University, New York, NY 10027 (United States); Devriendt, Julien [Department of Physics, University of Oxford, The Denys Wilkinson Building, Keble Rd., Oxford OX1 3RH (United Kingdom); Ceverino, Daniel [Zentrum für Astronomie der Universität Heidelberg, Institut für Theoretische Astrophysik, Albert-Ueberle-Str. 2, D-69120 Heidelberg (Germany); Kereš, Dušan [Department of Physics, Center for Astrophysics and Space Sciences, University of California at San Diego, 9500 Gilman Dr., La Jolla, CA 92093 (United States); Hopkins, Philip F. [California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125 (United States); Faucher-Giguère, Claude-André [Department of Physics and Astronomy and CIERA, Northwestern University, 2145 Sheridan Rd., Evanston, IL 60208 (United States)

    2017-07-01

    We investigate angular momentum acquisition in Milky Way-sized galaxies by comparing five high resolution zoom-in simulations, each implementing identical cosmological initial conditions but utilizing different hydrodynamic codes: Enzo, Art, Ramses, Arepo, and Gizmo-PSPH. Each code implements a distinct set of feedback and star formation prescriptions. We find that while many galaxy and halo properties vary between the different codes (and feedback prescriptions), there is qualitative agreement on the process of angular momentum acquisition in the galaxy’s halo. In all simulations, cold filamentary gas accretion to the halo results in ∼4 times more specific angular momentum in cold halo gas ( λ {sub cold} ≳ 0.1) than in the dark matter halo. At z > 1, this inflow takes the form of inspiraling cold streams that are co-directional in the halo of the galaxy and are fueled, aligned, and kinematically connected to filamentary gas infall along the cosmic web. Due to the qualitative agreement among disparate simulations, we conclude that the buildup of high angular momentum halo gas and the presence of these inspiraling cold streams are robust predictions of Lambda Cold Dark Matter galaxy formation, though the detailed morphology of these streams is significantly less certain. A growing body of observational evidence suggests that this process is borne out in the real universe.

  14. Are ancient dwarf satellites the building blocks of the Galactic halo?

    Science.gov (United States)

    Spitoni, E.; Vincenzo, F.; Matteucci, F.; Romano, D.

    2016-05-01

    According to the current cosmological cold dark matter paradigm, the Galactic halo could have been the result of the assemblage of smaller structures. Here we explore the hypothesis that the classical and ultra-faint dwarf spheroidal satellites of the Milky Way have been the building blocks of the Galactic halo by comparing their [α/Fe] and [Ba/Fe] versus [Fe/H] patterns with the ones observed in Galactic halo stars. The α elements deviate substantially from the observed abundances in the Galactic halo stars for [Fe/H] values larger than -2 dex, while they overlap for lower metallicities. On the other hand, for the [Ba/Fe] ratio, the discrepancy is extended at all [Fe/H] values, suggesting that the majority of stars in the halo are likely to have been formed in situ. Therefore, we suggest that [Ba/Fe] ratios are a better diagnostic than [α/Fe] ratios. Moreover, for the first time we consider the effects of an enriched infall of gas with the same chemical abundances as the matter ejected and/or stripped from dwarf satellites of the Milky Way on the chemical evolution of the Galactic halo. We find that the resulting chemical abundances of the halo stars depend on the assumed infall time-scale, and the presence of a threshold in the gas for star formation. In particular, in models with an infall time-scale for the halo around 0.8 Gyr coupled with a threshold in the surface gas density for the star formation (4 M⊙ pc-2), and the enriched infall from dwarf spheroidal satellites, the first halo stars formed show [Fe/H]>-2.4 dex. In this case, to explain [α/Fe] data for stars with [Fe/H]<-2.4 dex, we need stars formed in dSph systems.

  15. ELUCID. IV. Galaxy Quenching and its Relation to Halo Mass, Environment, and Assembly Bias

    Science.gov (United States)

    Wang, Huiyuan; Mo, H. J.; Chen, Sihan; Yang, Yang; Yang, Xiaohu; Wang, Enci; van den Bosch, Frank C.; Jing, Yipeng; Kang, Xi; Lin, Weipeng; Lim, S. H.; Huang, Shuiyao; Lu, Yi; Li, Shijie; Cui, Weiguang; Zhang, Youcai; Tweed, Dylan; Wei, Chengliang; Li, Guoliang; Shi, Feng

    2018-01-01

    We examine the quenched fraction of central and satellite galaxies as a function of galaxy stellar mass, halo mass, and the matter density of their large-scale environment. Matter densities are inferred from our ELUCID simulation, a constrained simulation of the local universe sampled by SDSS, while halo masses and central/satellite classification are taken from the galaxy group catalog of Yang et al. The quenched fraction for the total population increases systematically with the three quantities. We find that the “environmental quenching efficiency,” which quantifies the quenched fraction as a function of halo mass, is independent of stellar mass. And this independence is the origin of the stellar mass independence of density-based quenching efficiency found in previous studies. Considering centrals and satellites separately, we find that the two populations follow similar correlations of quenching efficiency with halo mass and stellar mass, suggesting that they have experienced similar quenching processes in their host halo. We demonstrate that satellite quenching alone cannot account for the environmental quenching efficiency of the total galaxy population, and that the difference between the two populations found previously arises mainly from the fact that centrals and satellites of the same stellar mass reside, on average, in halos of different mass. After removing these effects of halo mass and stellar mass, there remains a weak, but significant, residual dependence on environmental density, which is eliminated when halo assembly bias is taken into account. Our results therefore indicate that halo mass is the prime environmental parameter that regulates the quenching of both centrals and satellites.

  16. Galactic googly: the rotation-metallicity bias in the inner stellar halo of the Milky Way

    Science.gov (United States)

    Kafle, Prajwal R.; Sharma, Sanjib; Robotham, Aaron S. G.; Pradhan, Raj K.; Guglielmo, Magda; Davies, Luke J. M.; Driver, Simon P.

    2017-09-01

    The first and second moments of stellar velocities encode important information about the formation history of the Galactic halo. However, due to the lack of tangential motion and inaccurate distances of the halo stars, the velocity moments in the Galactic halo have largely remained 'known unknowns'. Fortunately, our off-centric position within the Galaxy allows us to estimate these moments in the galactocentric frame using the observed radial velocities of the stars alone. We use these velocities coupled with the hierarchical Bayesian scheme, which allows easy marginalization over the missing data (the proper motion, and uncertainty-free distance and line-of-sight velocity), to measure the velocity dispersions, orbital anisotropy (β) and streaming motion (vrot) of the halo main-sequence turn-off (MSTO) and K-giant (KG) stars in the inner stellar halo (r ≲ 15 kpc). We study the metallicity bias in kinematics of the halo stars and observe that the comparatively metal-rich ([Fe/H] > -1.4) and the metal-poor ([Fe/H] ≤ -1.4) MSTO samples show a clear systematic difference in vrot ∼ 20-40 km s - 1, depending on how restrictive the spatial cuts to cull the disc contamination are. The bias is also detected in KG samples but with less certainty. Both MSTO and KG populations suggest that the inner stellar halo of the Galaxy is radially biased i.e. σr > σθ or σϕ and β ≃ 0.5. The apparent metallicity contrariety in the rotation velocity among the halo sub-populations supports the co-existence of multiple populations in the galactic halo that may have formed through distinct formation scenarios, i.e. in situ versus accretion.

  17. Cosmic web alignments with the shape, angular momentum and peculiar velocities of dark matter haloes

    Science.gov (United States)

    Forero-Romero, Jaime E.; Contreras, Sergio; Padilla, Nelson

    2014-09-01

    We study the alignment of dark matter haloes with the cosmic web characterized by the tidal and velocity shear fields. We focus on the alignment of their shape, angular momentum and peculiar velocities. We use a cosmological N-body simulation that allows us to study dark matter haloes spanning almost five orders of magnitude in mass (109-1014) h-1 M⊙ and spatial scales of (0.5-1.0) h-1 Mpc to define the cosmic web. The strongest alignment is measured for halo shape along the smallest tidal eigenvector, e.g. along filaments and walls, with a signal that gets stronger as the halo mass increases. In the case of the velocity shear field only massive haloes >1012 h-1 M⊙ tend to have their shapes aligned along the largest tidal eigenvector, i.e. perpendicular to filaments and walls. For the angular momentum we find alignment signals only for haloes more massive than 1012 h-1 M⊙ both in the tidal and velocity shear fields where the preferences is to be parallel to the middle eigenvector; perpendicular to filaments and parallel to walls. Finally, the peculiar velocities show a strong alignment along the smallest tidal eigenvector for all halo masses; haloes move along filaments and walls. The same alignment is present with the velocity shear, albeit weaker and only for haloes less massive than 1012 h-1 M⊙. Our results show that the two different algorithms used to define the cosmic web describe different physical aspects of non-linear collapse and should be used in a complementary way to understand the cosmic web influence on galaxy evolution.

  18. Use of the "blue halo" assay in the identification of genes encoding exported proteins with cleavable signal peptides: cloning of a Borrelia burgdorferi plasmid gene with a signal peptide.

    Science.gov (United States)

    Giladi, M; Champion, C I; Haake, D A; Blanco, D R; Miller, J F; Miller, J N; Lovett, M A

    1993-07-01

    We have recently reported a phoA expression vector, termed pMG, which, like TnphoA, is useful in identifying genes encoding membrane-spanning sequences or signal peptides. This cloning system has been modified to facilitate the distinction of outer membrane and periplasmic alkaline phosphatase (AP) fusion proteins from inner membrane AP fusion proteins by transforming pMG recombinants into Escherichia coli KS330, the strain utilized in the "blue halo" assay first described by Strauch and Beckwith (Proc. Natl. Acad. Sci. USA 85:1576-1580, 1988). The lipoprotein mutation lpp-5508 of KS330 results in an outer membrane that is leaky to macromolecules, and its degP4 mutation greatly reduces periplasmic proteolytic degradation of AP fusion proteins. pMG AP fusions containing cleavable signal peptides, including the E. coli periplasmic protein beta-lactamase, the E. coli and Chlamydia trachomatis outer membrane proteins OmpA and MOMP, respectively, and Tp 9, a Treponema pallidum AP recombinant, diffused through the leaky outer membrane of KS330 and resulted in blue colonies with blue halos. In contrast, inner membrane AP fusions derived from E. coli proteins, including leader peptidase, SecY, and the tetracycline resistance gene product, as well as Tp 70, a T. pallidum AP recombinant which does not contain a signal peptide, resulted in blue colonies without blue halos. Lipoprotein-AP fusions, including the Borrelia burgdorferi OspA and T. pallidum Tp 75 and TmpA showed halo formation, although there was significantly less halo formation than that produced by either periplasmic or outer membrane AP fusions. In addition, we applied this approach to screen recombinants constructed from a 9.0-kb plasmid isolated from the B31 virulent strain of B. burgdorferi. One of the blue halo colonies identified produced an AP fusion protein which contained a signal peptide with a leader peptidase I cleavage recognition site. The pMG/KS330r- cloning and screening approach can identify

  19. First Observation of the LHC Beam Halo Using a Synchrotron Radiation Coronagraph

    OpenAIRE

    Mitsuhashi, Toshiyuki; Bravin, Enrico; Roncarolo, Federico; Trad, Georges

    2017-01-01

    A test coronagraph for the observation of beam halo has been installed in the Synchrotron radiation monitor line LHCB2 in 2015. This coronagraph is commissioned with LHC operation at 450GeV (injection energy). After some optical testing of the coronagraph with visible Synchrotron radiation in B2, we try to observe artificially-made beam halo. The beam halo of 10⁻³ order of magnitude against the beam core is excited by the kicker of the transverse damper. We have succeeded to observe a diffrac...

  20. SeNtInel 5P validaTion by Comet HALO

    OpenAIRE

    Fix, Andreas; Ehret, Gerhard; Bovensmann, Heinrich; Gerbig, Christoph; Pfeilsticker, K.; Zöger, Martin

    2015-01-01

    The goal of the proposed activity is the validation of the methane column of S5P using aircraft measurements. The airborne platform foreseen is the German research aircraft HALO. A dedicated HALO science mission that is focused on the measurement of methane (and carbon dioxide), dubbed CoMet, has been evaluated by the scientific steering committee of HALO and is now scheduled for the 1st half of 2017. In order to maximize gain, the team proposes to make use of the gathered data from this...

  1. The dearth of halo dwarf galaxies: is there power on short scales?

    Science.gov (United States)

    Kamionkowski; Liddle

    2000-05-15

    N-body simulations of structure formation with scale-invariant primordial perturbations show significantly more virialized objects of dwarf-galaxy mass in a typical galactic halo than are observed around the Milky Way. We show that the dearth of observed dwarf galaxies could be explained by a dramatic downturn in the power spectrum at small distance scales. This suppression of small-scale power might also help mitigate the disagreement between cuspy simulated halos and smooth observed halos, while remaining consistent with Lyman-alpha-forest constraints on small-scale power. Such a spectrum could arise in inflationary models with broken-scale invariance.

  2. Evidence of lensing of the cosmic microwave background by dark matter halos.

    Science.gov (United States)

    Madhavacheril, Mathew; Sehgal, Neelima; Allison, Rupert; Battaglia, Nick; Bond, J Richard; Calabrese, Erminia; Caligiuri, Jerod; Coughlin, Kevin; Crichton, Devin; Datta, Rahul; Devlin, Mark J; Dunkley, Joanna; Dünner, Rolando; Fogarty, Kevin; Grace, Emily; Hajian, Amir; Hasselfield, Matthew; Hill, J Colin; Hilton, Matt; Hincks, Adam D; Hlozek, Renée; Hughes, John P; Kosowsky, Arthur; Louis, Thibaut; Lungu, Marius; McMahon, Jeff; Moodley, Kavilan; Munson, Charles; Naess, Sigurd; Nati, Federico; Newburgh, Laura; Niemack, Michael D; Page, Lyman A; Partridge, Bruce; Schmitt, Benjamin; Sherwin, Blake D; Sievers, Jon; Spergel, David N; Staggs, Suzanne T; Thornton, Robert; Van Engelen, Alexander; Ward, Jonathan T; Wollack, Edward J

    2015-04-17

    We present evidence of the gravitational lensing of the cosmic microwave background by 10(13) solar mass dark matter halos. Lensing convergence maps from the Atacama Cosmology Telescope Polarimeter (ACTPol) are stacked at the positions of around 12 000 optically selected CMASS galaxies from the SDSS-III/BOSS survey. The mean lensing signal is consistent with simulated dark matter halo profiles and is favored over a null signal at 3.2σ significance. This result demonstrates the potential of microwave background lensing to probe the dark matter distribution in galaxy group and galaxy cluster halos.

  3. Detecting the Disruption of Dark-Matter Halos with Stellar Streams.

    Science.gov (United States)

    Bovy, Jo

    2016-03-25

    Narrow stellar streams in the Milky Way halo are uniquely sensitive to dark-matter subhalos, but many of these subhalos may be tidally disrupted. I calculate the interaction between stellar and dark-matter streams using analytical and N-body calculations, showing that disrupting objects can be detected as low-concentration subhalos. Through this effect, we can constrain the lumpiness of the halo as well as the orbit and present position of individual dark-matter streams. This will have profound implications for the formation of halos and for direct- and indirect-detection dark-matter searches.

  4. Industrial fluoride pollution of Jerbi grape leaves and the distribution of F,Ca, Mg, and P in them

    OpenAIRE

    Ben Abdallah, Ferjani; Elloumi, Nada; Mezghani, Imed; Garrec, Jean-Pierre; Boukhris, Makki

    2006-01-01

    Fluoride damaged leaves of the Jerbi grape vine tree (Vitis vinifera L) growing in the vicinity of a phosphate fertilizer manufacturing plant near Sfax, Tunisia, were used to study the distribution of the chemical elements F, Ca, Mg, and P in the leaves and stalks. Photosynthesis and the chlorophyll content of healthy leaf parts were also investigated to determine tolerance mechanisms of this species to fluoride. The subdivision of the necrotic zone into concentric necrotic halos evidently re...

  5. Studies of enzyme mechanism using isotopic probes

    Energy Technology Data Exchange (ETDEWEB)

    Chen, C.

    1987-01-01

    The isotope partitioning studies of the Ascaris suum NAD-malic enzyme reaction were examined with five transitory complexes including E:NAD, E:NAD:Mg, E:malate, E:Mg:malate, and E:NAD:malate. Three productive complexes, E:NAD, E:NAD:Mg, and E:Mg:malate, were obtained, suggesting a steady-state random mechanism. Data for trapping with E:/sup 14/C-NAD indicate a rapid equilibrium addition of Mg/sup 2 +/ prior to the addition of malate. Trapping with /sup 14/C-malate could only be obtained from the E:Mg/sup 2 +/:/sup 14/C-malate complex, while no trapping from E:/sup 14/C-malate was obtained under feasible experimental conditions. The equations for the isotope partitioning studies varying two substrates in the chase solution in an ordered terreactant reaction were derived, allowing a determination of the relative rates of substrate dissociation to the catalytic reaction for each of the productive transitory complexes. NAD and malate are released from the central complex at an identical rate, equal to the catalytic rate. The release of NAD from E:NAD and E:NAD:Mg complexes is 2- to 4-fold and 5- to 9-fold V/sub max//E/sub t/, respectively. The release of malate from the E:Mg:malate complex is 0.1- to 0.3-fold of V/sub max//E/sub t/. The individual rate constants for association and dissociation of the substrates, NAD and malate have been estimated.

  6. STELLAR MASS-GAP AS A PROBE OF HALO ASSEMBLY HISTORY AND CONCENTRATION: YOUTH HIDDEN AMONG OLD FOSSILS

    Energy Technology Data Exchange (ETDEWEB)

    Deason, A. J.; Conroy, C. [Department of Astronomy and Astrophysics, University of California Santa Cruz, Santa Cruz, CA 95064 (United States); Wetzel, A. R. [Department of Astronomy, Yale University, New Haven, CT 06520 (United States); Tinker, J. L., E-mail: alis@ucolick.org [Center for Cosmology and Particle Physics, Department of Physics, New York University, New York, NY 10013 (United States)

    2013-11-10

    We investigate the use of the halo mass-gap statistic—defined as the logarithmic difference in mass between the host halo and its most massive satellite subhalo—as a probe of halo age and concentration. A cosmological N-body simulation is used to study N ∼ 25, 000 group/cluster-sized halos in the mass range 10{sup 12.5} < M{sub halo}/M{sub ☉} < 10{sup 14.5}. In agreement with previous work, we find that halo mass-gap is related to halo formation time and concentration. On average, older and more highly concentrated halos have larger halo mass-gaps, and this trend is stronger than the mass-concentration relation over a similar dynamic range. However, there is a large amount of scatter owing to the transitory nature of the satellite subhalo population, which limits the use of the halo mass-gap statistic on an object-by-object basis. For example, we find that 20% of very large halo mass-gap systems (akin to {sup f}ossil groups{sup )} are young and have likely experienced a recent merger between a massive satellite subhalo and the central subhalo. We relate halo mass-gap to the observable stellar mass-gap via abundance matching. Using a galaxy group catalog constructed from the Sloan Digital Sky Survey Data Release 7, we find that the star formation and structural properties of galaxies at fixed mass show no trend with stellar mass-gap. This is despite a variation in halo age of ≈2.5 Gyr over ≈1.2 dex in stellar mass-gap. Thus, we find no evidence to suggest that the halo formation history significantly affects galaxy properties.

  7. Charge radii of neon isotopes across the sd neutron shell

    CERN Document Server

    Marinova, K; Kowalska, M; Kotrotsios, G; Kloos, S; Neugart, R; Blaum, K; Simon, H; Keim, M; Lievens, P; Wilbert, S; Kappertz, S

    2011-01-01

    We report on the changes in mean square charge radii of unstable neon nuclei relative to the stable (20)Ne, based on the measurement of optical isotope shifts. The studies were carried out using collinear laser spectroscopy on a fast beam of neutral neon atoms. High sensitivity on short-lived isotopes was achieved thanks to nonoptical detection based on optical pumping and state-selective collisional ionization, which was complemented by an accurate determination of the beam kinetic energy. The new results provide information on the structural changes in the sequence of neon isotopes all across the neutron sd shell, ranging from the proton drip line nucleus and halo candidate (17)Ne up to the neutron-rich (28)Ne in the vicinity of the ``island of inversion.{''} Within this range the charge radius is smallest for (24)Ne with N = 14 corresponding to the closure of the neutron d(5/2) shell, while it increases toward both neutron shell closures, N = 8 and N = 20. The general trend of the charge radii correlates w...

  8. Isotopes through the looking glass

    Science.gov (United States)

    Mårtensson Pendrill, Ann Marie

    2000-08-01

    Nuclear distributions affect many aspects of atomic spectra. As an example, recent experimental results for the hyperfine anomaly in Fr isotopes are considered. These depend on nuclear charge and magnetization distributions. The variations in charge radii for these isotopes were studied earlier by measuring optical isotope shifts. The hyperfine anomalies for the odd-odd isotopes involve the neutron distributions, of interest for studies of parity nonconserving effects along a chain of isotopes.

  9. Calcium stable isotope geochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Gausonne, Nikolaus [Muenster Univ. (Germany). Inst. fuer Mineralogie; Schmitt, Anne-Desiree [Strasbourg Univ. (France). LHyGeS/EOST; Heuser, Alexander [Bonn Univ. (Germany). Steinmann-Inst. fuer Geologie, Mineralogie und Palaeontologie; Wombacher, Frank [Koeln Univ. (Germany). Inst. fuer Geologie und Mineralogie; Dietzel, Martin [Technische Univ. Graz (Austria). Inst. fuer Angewandte Geowissenschaften; Tipper, Edward [Cambridge Univ. (United Kingdom). Dept. of Earth Sciences; Schiller, Martin [Copenhagen Univ. (Denmark). Natural History Museum of Denmark

    2016-08-01

    This book provides an overview of the fundamentals and reference values for Ca stable isotope research, as well as current analytical methodologies including detailed instructions for sample preparation and isotope analysis. As such, it introduces readers to the different fields of application, including low-temperature mineral precipitation and biomineralisation, Earth surface processes and global cycling, high-temperature processes and cosmochemistry, and lastly human studies and biomedical applications. The current state of the art in these major areas is discussed, and open questions and possible future directions are identified. In terms of its depth and coverage, the current work extends and complements the previous reviews of Ca stable isotope geochemistry, addressing the needs of graduate students and advanced researchers who want to familiarize themselves with Ca stable isotope research.

  10. Isotope Production Facility (IPF)

    Data.gov (United States)

    Federal Laboratory Consortium — The Los Alamos National Laboratory has produced radioactive isotopes for medicine and research since the mid 1970s, when targets were first irradiated using the 800...

  11. Isotopes in Greenland Precipitation

    DEFF Research Database (Denmark)

    Faber, Anne-Katrine

    ) Constructing a new Greenland database of observations and present-day ice core measurements, and (3) Performance test of isotope-enabled CAM5 for Greenland. The recent decades of rapid Arctic sea ice decline are used as a basis for an observational-based model experiment using the isotope-enabled CAM model 3....... The simulation of Greenland isotopes is tested for the isotope-enabled model CAM5. Here the importance of model resolution is investigated. A positive bias of 6-10 ‰ is found for the annual mean δ18O on the central part of the Greenland Ice Sheet. The amplitude of the seasonal cycle of Greenland δ18O is highly...

  12. Recoiling black holes in static and evolving dark matter halo potential

    Directory of Open Access Journals (Sweden)

    Smole M.

    2015-01-01

    Full Text Available We follow trajectories of kicked black holes in static and evolving dark matter halo potential. We explore both NFW and Einasto dark matter density distributions. Considered dark matter halos represent hosts of massive spiral and elliptical field galaxies. We study critical amplitude of kick velocity necessary for complete black hole ejection at various redshifts and find that ~40% lower kick velocities can remove black holes from their host haloes at z = 7 compared to z = 1. The greatest difference between static and evolving potential occurs near the critical velocity for black hole ejection and at high redshifts. When NFW and Einasto density distributions are compared ~30% higher kick velocities are needed for complete removal of BHs from dark matter halo described by NFW profile. [Projekat Ministarstva nauke Republike Srbije, br. 176021: Visible and invisible matter in nearby galaxies: Theory and observations

  13. Basal cell carcinoma with halo phenomenon in a young female: Significance of dermatoscopy in early diagnosis

    Directory of Open Access Journals (Sweden)

    Pinar Yuksel Basak

    2015-01-01

    Full Text Available Halo phenomenon of nevus may be observed as a circular reaction, although it is unusual around tumors. A 29-year-old woman presented with a pigmented lesion on the cheek since three years. She noted whitening of the skin around the lesion almost after a year following its appearance. Dermatologic examination revealed a pigmented nodular lesion with a hypopigmented halo on the left infraorbital region. The clinical impression was halo nevus, whereas basal cell carcinoma (BCC was considered in dermatoscopic differential diagnosis. The diagnosis was infiltrative-type BCC histopathologically. The persistence of a perilesional halo around an enlarging pigmented lesion should be carefully examined with accompanying dermatoscopic findings even in young patients for early diagnosis of tumoral lesions.

  14. Active halo control through narrow-band excitation with the ADT at injection

    CERN Document Server

    Wagner, Joschka; Garcia Morales, Hector; Redaelli, Stefano; Valentino, Gianluca; Valuch, Daniel; CERN. Geneva. ATS Department

    2016-01-01

    During this MD (MD1388), the capabilities of an active halo control for beam tail depletion in the LHC were tested. The studied method relies on using the Transverse Damper (ADT) to perform a narrow-band excitation.

  15. Methods for detection of protein-protein and protein-DNA interactions using HaloTag.

    Science.gov (United States)

    Urh, Marjeta; Hartzell, Danette; Mendez, Jacqui; Klaubert, Dieter H; Wood, Keith

    2008-01-01

    HaloTag is a protein fusion tag which was genetically engineered to covalently bind a series of specific synthetic ligands. All ligands carry two groups, the reactive group and the functional/reporter group. The reactive group, the choloroalkane, is the same in all the ligands and is involved in binding to the HaloTag. The functional reporter group is variable and can carry many different moieties including fluorescent dyes, affinity handles like biotin or solid surfaces such as agarose beads. Thus, HaloTag can serve either as a labeling tag or as a protein immobilization tag depending on which ligand is bound to it. Here, we describe a procedure for immobilization of HaloTag fusion proteins and how immobilized proteins can be used to study protein-protein and protein-DNA interactions in vivo and in vitro.

  16. The puzzling assembly of the Milky Way halo – contributions from dwarf Spheroidals and globular clusters

    Directory of Open Access Journals (Sweden)

    Lépine S.

    2012-02-01

    Full Text Available While recent sky surveys have uncovered large numbers of ever fainter Milky Way satellites, their classification as star clusters, low-luminosity galaxies, or tidal overdensities remains often unclear. Likewise, their contributions to the build-up of the halo is yet debated. In this contribution we will discuss the current knowledge of the stellar populations and chemo-dynamics in these puzzling satellites, with a particular focus on dwarf spheroidal galaxies and the globular clusters in the outer Galactic halo. Also the question of whether some of the outermost halo objects are dynamically associated with the (Milky Way halo at all is addressed in terms of proper measurements in the remote Leo I and II dwarf galaxies.

  17. A THEORY OF CONSUMER’S PERCEIVED RISK UNDER THE HALO EFFECT

    Directory of Open Access Journals (Sweden)

    Dorian-Laurenţiu FLOREA

    2015-06-01

    Full Text Available Despite being largely tackled by a manifold of sciences, perceived risk is still a rather unclear concept concerning its formation and update. In today’s economy, where poor purchase decisions are so easy to make, consumers have developed mental shields residing in actions based on perceived risk. This paper develops and tests a theory of perceived risk formation under the halo effect, based on correlation analysis in two forms: rankings individuals on their contribution to the correlations increase and partial correlations. Both internal and external halo effects were found, emerging from the perceived risk component – functional risk, financial risk, social risk, physical risk, psychological risk and time risk –, brand attitude, product category attitude, consumer’s regret, others’ regret expressed through word-of-mouth, recency, and awareness of awareness. The intricate halo that was revealed needs further attention from the scientific community in order to better delimit halo sources and, eventually, to explain its variability.

  18. UARS Halogen Occultation Experiment (HALOE) Level 2 V019 (UARHA2FN) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — The Halogen Occultation Experiment (HALOE) Level 2 data product consists of daily vertical profiles of temperature, aerosol extinciton and pressure, as well as...

  19. UARS Halogen Occultation Experiment (HALOE) Level 3AT V019 (UARHA3AT) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — The Halogen Occultation Experiment (HALOE) Level 3AT data product consists of daily vertical profiles of temperature, aerosol extinction and concentrations of HCl,...

  20. Recoiling Black Holes in Static and Evolving Dark Matter Halo Potential

    Science.gov (United States)

    Smole, M.

    2015-12-01

    We follow trajectories of kicked black holes in static and evolving dark matter halo potential. We explore both NFW and Einasto dark matter density distributions. The considered dark matter halos represent hosts of massive spiral and elliptical field galaxies. We study the critical amplitude of kick velocity necessary for complete black hole ejection at various redshifts and find that ˜40 percent lower kick velocities can remove black holes from their host haloes at z=7 compared to z=1. The greatest difference between the static and evolving potential occurs near the critical velocity for black hole ejection and at high redshifts. When NFW and Einasto density distributions are compared ˜30 percent higher kick velocities are needed for complete removal of BHs from dark matter halo described by the NFW profile.

  1. Exploring Milkyway Halo Substructures with Large-Area Sky Surveys

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ting [Texas A & M Univ., College Station, TX (United States)

    2016-01-01

    Over the last two decades, our understanding of the Milky Way has been improved thanks to large data sets arising from large-area digital sky surveys. The stellar halo is now known to be inhabited by a variety of spatial and kinematic stellar substructures, including stellar streams and stellar clouds, all of which are predicted by hierarchical Lambda Cold Dark Matter models of galaxy formation. In this dissertation, we first present the analysis of spectroscopic observations of individual stars from the two candidate structures discovered using an M-giant catalog from the Two Micron All-Sky Survey. The follow-up observations show that one of the candidates is a genuine structure which might be associated with the Galactic Anticenter Stellar Structure, while the other one is a false detection due to the systematic photometric errors in the survey or dust extinction in low Galactic latitudes. We then presented the discovery of an excess of main sequence turn-off stars in the direction of the constellations of Eridanus and Phoenix from the first-year data of the Dark Energy Survey (DES) – a five-year, 5,000 deg2 optical imaging survey in the Southern Hemisphere. The Eridanus-Phoenix (EriPhe) overdensity is centered around l ~ 285° and b ~ -60° and the Poisson significance of the detection is at least 9σ. The EriPhe overdensity has a cloud-like morphology and the extent is at least ~ 4 kpc by ~ 3 kpc in projection, with a heliocentric distance of about d ~ 16 kpc. The EriPhe overdensity is morphologically similar to the previously-discovered Virgo overdensity and Hercules-Aquila cloud. These three overdensities lie along a polar plane separated by ~ 120° and may share a common origin. In addition to the scientific discoveries, we also present the work to improve the photometric calibration in DES using auxiliary calibration systems, since the photometric errors can cause false detection in first the halo substructure. We present a detailed description of the two

  2. Isotope toolbox turns 10

    DEFF Research Database (Denmark)

    Wenander, Fredrik; Riisager, Karsten

    2012-01-01

    REX-ISOLDE, one of CERN’s most compact accelerators, has just celebrated its 10th anniversary. The machine’s versatility provides radioactive ion beams across the range of nuclear isotopes.......REX-ISOLDE, one of CERN’s most compact accelerators, has just celebrated its 10th anniversary. The machine’s versatility provides radioactive ion beams across the range of nuclear isotopes....

  3. Isotope research materials

    Energy Technology Data Exchange (ETDEWEB)

    Wilkinson, M. K.; Young, Jr, F. W.

    1977-10-01

    Preparation of research isotope materials is described. Topics covered include: separation of tritium from aqueous effluents by bipolar electrolysis; stable isotope targets and research materials; radioisotope targets and research materials; preparation of an 241Am metallurgical specimen; reactor dosimeters; ceramic and cermet development; fission-fragment-generating targets of 235UO2; and wire dosimeters for Westinghouse--Bettis. (GHT)

  4. Magnesium stable isotope ecology using mammal tooth enamel.

    Science.gov (United States)

    Martin, Jeremy E; Vance, Derek; Balter, Vincent

    2015-01-13

    Geochemical inferences on ancient diet using bone and enamel apatite rely mainly on carbon isotope ratios (δ(13)C) and to a lesser extent on strontium/calcium (Sr/Ca) and barium/calcium (Ba/Ca) elemental ratios. Recent developments in nontraditional stable isotopes provide an unprecedented opportunity to use additional paleodietary proxies to disentangle complex diets such as omnivory. Of particular relevance for paleodietary reconstruction are metals present in large quantity in bone and enamel apatite, providing that biologically mediated fractionation processes are constrained. Calcium isotope ratios (δ(44)Ca) meet these criteria but exhibit complex ecological patterning. Stable magnesium isotope ratios (δ(26)Mg) also meet these criteria but a comprehensive understanding of its variability awaits new isotopic data. Here, 11 extant mammal species of known ecology from a single locality in equatorial Africa were sampled for tooth enamel and, together with vegetation and feces, analyzed for δ(26)Mg, δ(13)C, Sr/Ca, and Ba/Ca ratios. The results demonstrate that δ(26)Mg incorporated in tooth enamel becomes heavier from strict herbivores to omnivores/faunivores. Using data from experimentally raised sheep, we suggest that this (26)Mg enrichment up the trophic chain is due to a (26)Mg enrichment in muscle relative to bone. Notably, it is possible to distinguish omnivores from herbivores, using δ(26)Mg coupled to Ba/Ca ratios. The potential effects of metabolic and dietary changes on the enamel δ(26)Mg composition remain to be explored but, in the future, multiproxy approaches would permit a substantial refinement of dietary behaviors or enable accurate trophic reconstruction despite specimen-limited sampling, as is often the case for fossil assemblages.

  5. The effect of J{sub 2} on equatorial and halo orbits around a magnetic planet

    Energy Technology Data Exchange (ETDEWEB)

    Inarrea, Manuel [Universidad de la Rioja, Area de Fisica, 26006 Logrono (Spain); Lanchares, Victor [Dpto. de Matematicas y Computacion, CIEMUR: Centro de Investigacion en Informatica, Estadistica y Matematicas, Universidad de la Rioja, 26004 Logrono (Spain)], E-mail: vlancha@unirioja.es; Palacian, Jesus F. [Universidad Publica de Navarra, Departamento de Ingenieria Matematica e Informatica, 31006 Pamplona (Spain); Pascual, Ana I. [Dpto. de Matematicas y Computacion, CIEMUR: Centro de Investigacion en Informatica, Estadistica y Matematicas, Universidad de la Rioja, 26004 Logrono (Spain); Pablo Salas, J. [Universidad de la Rioja, Area de Fisica, 26006 Logrono (Spain); Yanguas, Patricia [Universidad Publica de Navarra, Departamento de Ingenieria Matematica e Informatica, 31006 Pamplona (Spain)

    2009-10-15

    We calculate equatorial and halo orbits around a non-spherical (both oblate and prolate) magnetic planet. It is known that circular equatorial and halo orbits exist for a dust grain orbiting a spherical magnetic planet. However, the frequency of the orbit is constrained by the charge-mass ratio of the particle. If the non-sphericity of the planet is taken into account this constraint is modified or, in some cases, it disappears.

  6. Search for baryonic dark matter in the halo of the Galaxy

    Science.gov (United States)

    Crézé, Michel; Robin, Annie C.; Mohan, Vijay; Reylé, Céline; Cuillandre, Jean-Charles

    2001-05-01

    A proper motion survey at the north galactic pole have been performed at the CFHT on a 4 year time baseline. We investigate for the presence of ancient white dwarfs in the sample and determine their possible contribution to the local density of the dark Halo. In the volume explored no candidate was detected, giving an upper limit to the ancient white dwarf fraction in the dark halo of 20% at most.

  7. Probing the structure of the cold dark matter halo using ancient mica

    Science.gov (United States)

    Baltz, Edward A.; Westphal, Andrew J.; Snowden-Ifft, Daniel P.

    1999-01-01

    Mica can store (for >1 Gyr) etchable tracks caused by atoms recoiling from WIMPs. Ancient mica is a directional detector despite the complex motions it makes with respect to the WIMP ``wind.'' We can exploit the properties of directionality and long integration time to probe for structure in the dark matter halo of our galaxy. We compute a sample of possible signals in mica for a plausible model of halo structure.

  8. Baryon effects on the dark matter haloes constrained from strong gravitational lensing

    Science.gov (United States)

    Wang, Lin; Chen, Da-Ming; Li, Ran

    2017-10-01

    Simulations are expected to be a powerful tool to investigate the baryon effects on dark matter (DM) haloes. Recent high resolution, cosmological hydrodynamic simulations predict that the inner density profiles of DM haloes depend systematically on the ratio of stellar to DM mass (M*/Mhalo), which is thought to be able to provide good fits to the observed rotation curves of galaxies. The Di Cintio et al. (hereafter DC14) profile is fitted from the simulations that are confined to Mhalo ≤ 1012 M⊙; in order to investigate the physical processes that may affect all haloes, we extrapolate it to much larger halo mass, including that of galaxy clusters. The inner slope of the DC14 profile is flat for low halo mass, it approaches 1 when the halo mass increases towards 1012 M⊙ and decreases rapidly after that mass. We use the DC14 profile for lenses and find that it predicts too few lenses compared with the most recent strong lensing observations Sloan Digital Sky Survey Quasar Lens Search (SQLS). We also calculate the strong lensing probabilities for a simulated density profile that continues the halo mass from the mass end of DC14 (∼1012 M⊙) to the mass that covers the galaxy clusters, and find that this Schaller et al. (hereafter Schaller15) model predict too many lenses compared with other models and SQLS observations. Interestingly, Schaller15 profile has no core, however, like DC14, the rotation curves of the simulated haloes are in excellent agreement with observational data. Furthermore, we show that the standard two-population model SIS+NFW cannot match the most recent SQLS observations for large image separations.

  9. The spin and orientation of dark matter halos within cosmic filaments

    OpenAIRE

    Zhang, Youcai; Yang, Xiaohu; Faltenbacher, Andreas; Springel, Volker; Lin, Weipeng; Wang, Huiyuan

    2009-01-01

    Clusters, filaments, sheets and voids are the building blocks of the cosmic web. In this study, we present and compare two distinct algorithms for finding cosmic filaments and sheets, a task which is far less well established than the identification of dark matter halos or voids. One method is based on the smoothed dark matter density field, the other uses the halo distributions directly. We apply both techniques to one high resolution N-body simulation and reconstruct the filamentary/sheet l...

  10. Galaxy formation with BECDM - I. Turbulence and relaxation of idealized haloes

    Science.gov (United States)

    Mocz, Philip; Vogelsberger, Mark; Robles, Victor H.; Zavala, Jesús; Boylan-Kolchin, Michael; Fialkov, Anastasia; Hernquist, Lars

    2017-11-01

    We present a theoretical analysis of some unexplored aspects of relaxed Bose-Einstein condensate dark matter (BECDM) haloes. This type of ultralight bosonic scalar field dark matter is a viable alternative to the standard cold dark matter (CDM) paradigm, as it makes the same large-scale predictions as CDM and potentially overcomes CDM's small-scale problems via a galaxy-scale de Broglie wavelength. We simulate BECDM halo formation through mergers, evolved under the Schrödinger-Poisson equations. The formed haloes consist of a soliton core supported against gravitational collapse by the quantum pressure tensor and an asymptotic r-3 NFW-like profile. We find a fundamental relation of the core-to-halo mass with the dimensionless invariant Ξ ≡ |E|/M3/(Gm/ℏ)2 or Mc/M ≃ 2.6Ξ1/3, linking the soliton to global halo properties. For r ≥ 3.5 rc core radii, we find equipartition between potential, classical kinetic and quantum gradient energies. The haloes also exhibit a conspicuous turbulent behaviour driven by the continuous reconnection of vortex lines due to wave interference. We analyse the turbulence 1D velocity power spectrum and find a k-1.1 power law. This suggests that the vorticity in BECDM haloes is homogeneous, similar to thermally-driven counterflow BEC systems from condensed matter physics, in contrast to a k-5/3 Kolmogorov power law seen in mechanically-driven quantum systems. The mode where the power spectrum peaks is approximately the soliton width, implying that the soliton-sized granules carry most of the turbulent energy in BECDM haloes.

  11. Live Imaging of Mitosomes and Hydrogenosomes by HaloTag Technology

    OpenAIRE

    Eva Martincová; Luboš Voleman; Vladimíra Najdrová; Maximiliano De Napoli; Shiri Eshar; Melisa Gualdron; Hopp, Christine S.; Sanin, David E; Dumizulu L Tembo; Daria Van Tyne; Dawn Walker; Michaela Marcinčiková; Jan Tachezy; Pavel Doležal

    2012-01-01

    Hydrogenosomes and mitosomes represent remarkable mitochondrial adaptations in the anaerobic parasitic protists such as Trichomonas vaginalis and Giardia intestinalis, respectively. In order to provide a tool to study these organelles in the live cells, the HaloTag was fused to G. intestinalis IscU and T. vaginalis frataxin and expressed in the mitosomes and hydrogenosomes, respectively. The incubation of the parasites with the fluorescent Halo-ligand resulted in highly specific organellar la...

  12. The HaloTag: Improving Soluble Expression and Applications in Protein Functional Analysis

    OpenAIRE

    N Peterson, Scott; Kwon, Keehwan

    2012-01-01

    Technological and methodological advances have been critical for the rapidly evolving field of proteomics. The development of fusion tag systems is essential for purification and analysis of recombinant proteins. The HaloTag is a 34 KDa monomeric protein derived from a bacterial haloalkane dehalogenase. The majority of fusion tags in use today utilize a reversible binding interaction with a specific ligand. The HaloTag system is unique in that it forms a covalent linkage to its chloroalkane l...

  13. The Eating Habits of Giants and Dwarfs: Chemo-dynamics of Halo Assembly in Nearby Galaxies

    Science.gov (United States)

    Romanowsky, Aaron J.; SAGES Team

    2012-01-01

    I will present novel results on the halo assembly of nearby galaxies, from dwarfs to the most massive ellipticals, using Subaru imaging and Keck spectroscopy. Field stars, globular clusters, and planetary nebulae are used as wide-field chemo-dynamical tracers, mapping out halo substructures that were previously known and unknown. Comparisons are made with simulations of galaxy formation. Supported by the National Science Foundation Grants AST-0808099, AST-0909237, and AST-1109878.

  14. Using frequency maps to explore the distribution function of the Milky Way stellar halo

    Directory of Open Access Journals (Sweden)

    Valluri M.

    2012-02-01

    Full Text Available Resolved surveys of the Milky Way's stellar halo can obtain all 6 phase space coordinates of tens of thousands of individual stars, making it possible to compute their 3-dimensional orbits. When frequency mapping is applied to such orbits they also represent the underlying phase space distribution function since the orbits that the are drawn from 3. A frequency maps clearly separates out the major types of orbits that constitute the DF and their relative abundances. The structure of the frequency maps, especially the locations of resonant orbits, reflects the formation history and shape of the dark matter potential and its orientation relative to the disk. The application of frequency analysis to cosmological hydrodynamic simulations of disk galaxies shows that the orbital families occupied by halo stars and dark matter particles are very similar, implying that stellar halo orbits can be used to constrain the DF of the dark matter halo, possibly impacting the interpretation of results from direct dark matter detection experiments. An application of these methods to a sample of ~ 16,000 Milky Way halo and thick disk stars from the SDSS-SEGUE survey yields a frequency map with strong evidence for resonant trapping of halo stars by the Milky Way disk, in a manner predicted by controlled simulations in which the disk grows adiabatically. The application of frequency analysis methods to current and future phase space data for Milky Way halo stars will provide new insights into the formation history of the different components of the Galaxy and the DF of the halo.

  15. X-ray scattered halo around IGR J17544–2619

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Junjie; Ling, Zhixing; Zhang, Shuang-Nan, E-mail: zhangsn@ihep.ac.cn [National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

    2014-04-10

    X-ray photons coming from an X-ray point source not only arrive at the detector directly, but also can be strongly forward-scattered by the interstellar dust along the line of sight (LOS), leading to a detectable diffuse halo around the X-ray point source. The geometry of small-angle X-ray scattering is straightforward, namely, the scattered photons travel longer paths and thus arrive later than the unscattered ones; thus, the delay time of X-ray scattered halo photons can reveal information of the distances of the interstellar dust and the point source. Here we present a study of the X-ray scattered halo around IGR J17544–2619, which is one of the so-called supergiant fast X-ray transients. IGR J17544–2619 underwent a striking outburst when observed with Chandra on 2004 July 3, providing a near δ-function light curve. We find that the X-ray scattered halo around IGR J17544–2619 is produced by two interstellar dust clouds along the LOS. The one that is closer to the observer gives the X-ray scattered halo at larger observational angles, whereas the farther one, which is in the vicinity of the point source, explains the halo with a smaller angular size. By comparing the observational angle of the scattered halo photons with that predicted by different dust grain models, we are able to determine the normalized dust distance. With the delay times of the scattered halo photons, we can determine the point source distance, given a dust grain model. Alternatively, we can discriminate between the dust grain models, if the point source distance is known independently.

  16. Effective description of dark matter self-interactions in small dark matter haloes

    OpenAIRE

    Kummer, Janis; Kahlhoefer, Felix; Schmidt-Hoberg, Kai

    2017-01-01

    Self-interacting dark matter may have striking astrophysical signatures, such as observable offsets between galaxies and dark matter in merging galaxy clusters. Numerical N-body simulations used to predict such observables typically treat the galaxies as collisionless test particles, a questionable assumption given that each galaxy is embedded in its own dark matter halo. To enable a more accurate treatment we develop an effective description of small dark matter haloes taking into account th...

  17. Two neutrons halos: from {sup 11}Li to {sup 22}C

    Energy Technology Data Exchange (ETDEWEB)

    Frederico, T. [Instituto Tecnologico de Aeronautica (ITA/CTA), Sao Jose dos Campos, SP (Brazil)

    2012-07-01

    Full text: The universal aspects of weakly-bound neutron-rich light nuclei will be discussed qualitatively and quantitatively, considering the cases where large two-neutron halos are formed. The low-energy properties of light halo nuclei with two and three-body structures (one- and two-neutron halos) dominated by s-wave two-body interactions will be addressed in respect to halo size and charge radii. We focus on the Borromean cases of {sup 11}Li and the recently discovered {sup 22}C. Due to the large size of the two-neutron halos in respect to the nuclear interaction range, the general properties associated with the halo neutrons tail are model independent. These halo properties obey scaling laws which are functions mainly dominated by the neutron-neutron and neutron-core scattering lengths, with an additional short-range scale that parameterizes the physics of the 2n-core system at the nuclear interaction range. The essential physics supporting the model independence of the scaling laws is the Thomas-Efimov phenomena, and the scaling laws for the s-wave two-neutron halos appears in practice as limit-cycles calculated in a renormalized zero-range three-body model. The different radii and charge radius of the Borromean 2n-core systems with s-wave interactions are determined by scaling laws calculated within the three-body model. For example, the charge radius of {sup 11}Li is in perfect agreement with data, despite the simplicity of the model. The possibility of these nuclei present s-wave near-threshold resonances are also discussed. These aspects were recently reviewed in Ref.1. [1] T. Frederico, A. Delfino, L. Tomio, M. T. Yamashita, Prog. Part. Nucl. Phys. 67 (2012) 939. (author)

  18. Tracing carbonate-silicate interaction during subduction using magnesium and oxygen isotopes.

    Science.gov (United States)

    Wang, Shui-Jiong; Teng, Fang-Zhen; Li, Shu-Guang

    2014-11-04

    Subduction of carbonates and carbonated eclogites into the mantle plays an important role in transporting carbon into deep Earth. However, to what degree isotopic exchanges occur between carbonate and silicate during subduction remains unclear. Here we report Mg and O isotopic compositions for ultrahigh pressure metamorphic marbles and enclosed carbonated eclogites from China. These marbles include both calcite- and dolomite-rich examples and display similar O but distinct Mg isotopic signatures to their protoliths. Their δ(26)Mg values vary from -2.508 to -0.531‰, and negatively correlate with MgO/CaO ratios, unforeseen in sedimentary carbonates. Carbonated eclogites have extremely heavy δ(18)O (up to +21.1‰) and light δ(26)Mg values (down to -1.928‰ in garnet and -0.980‰ in pyroxene) compared with their protoliths. These unique Mg-O isotopic characteristics reflect differential isotopic exchange between eclogites and carbonates during subduction, making coupled Mg and O isotopic studies potential tools for tracing deep carbon recycling.

  19. An Excursion Set Model of the Cosmic Web: the Abundance of Sheets, Filaments And Halos

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Jiajian; /Penn State U., Astron. Astrophys.; Abel, Tom; /KIPAC, Menlo Park; Mo, Houjun; /Massachusetts U., Amherst; Sheth, Ravi; /Pennsylvania U.

    2006-01-11

    We discuss an analytic approach for modeling structure formation in sheets, filaments and knots. This is accomplished by combining models of triaxial collapse with the excursion set approach: sheets are defined as objects which have collapsed along only one axis, filaments have collapsed along two axes, and halos are objects in which triaxial collapse is complete. In the simplest version of this approach, which we develop here, large scale structure shows a clear hierarchy of morphologies: the mass in large-scale sheets is partitioned up among lower mass filaments, which themselves are made-up of still lower mass halos. Our approach provides analytic estimates of the mass fraction in sheets, filaments and halos, and its evolution, for any background cosmological model and any initial fluctuation spectrum. In the currently popular {Lambda}CDM model, our analysis suggests that more than 99% of the mass in sheets, and 72% of the mass in filaments, is stored in objects more massive than 10{sup 10}M{sub {circle_dot}} at the present time. For halos, this number is only 46%. Our approach also provides analytic estimates of how halo abundances at any given time correlate with the morphology of the surrounding large-scale structure, and how halo evolution correlates with the morphology of large scale structure.

  20. A study of halo and relic radio emission in merging clusters using the Murchison Widefield Array

    Science.gov (United States)

    George, L. T.; Dwarakanath, K. S.; Johnston-Hollitt, M.; Intema, H. T.; Hurley-Walker, N.; Bell, M. E.; Callingham, J. R.; For, Bi-Qing; Gaensler, B.; Hancock, P. J.; Hindson, L.; Kapińska, A. D.; Lenc, E.; McKinley, B.; Morgan, J.; Offringa, A.; Procopio, P.; Staveley-Smith, L.; Wayth, R. B.; Wu, Chen; Zheng, Q.

    2017-05-01

    We have studied radio haloes and relics in nine merging galaxy clusters using the Murchison Widefield Array (MWA). The images used for this study were obtained from the GaLactic and Extragalactic All-sky MWA (GLEAM) Survey which was carried out at five frequencies, viz. 88, 118, 154, 188 and 215 MHz. We detect diffuse radio emission in eight of these clusters. We have estimated the spectra of haloes and relics in these clusters over the frequency range 80-1400 MHz; the first such attempt to estimate their spectra at low frequencies. The spectra follow a power law with a mean value of α = -1.13 ± 0.21 for haloes and α = -1.2 ± 0.19 for relics, where S ∝ να. We reclassify two of the cluster sources as radio galaxies. The low-frequency spectra are thus an independent means of confirming the nature of cluster sources. Five of the nine clusters host radio haloes. For the remaining four clusters, we place upper limits on the radio powers of possible haloes in them. These upper limits are a factor of 2-20 below those expected from the LX-P1.4 relation. These limits are the lowest ever obtained and the implications of these limits to the hadronic model of halo emission are discussed.

  1. The MICE Grand Challenge lightcone simulation - II. Halo and galaxy catalogues

    Science.gov (United States)

    Crocce, M.; Castander, F. J.; Gaztañaga, E.; Fosalba, P.; Carretero, J.

    2015-10-01

    This is the second in a series of three papers in which we present an end-to-end simulation from the MICE collaboration, the MICE Grand Challenge (MICE-GC) run. The N-body contains about 70 billion dark-matter particles in a (3 h-1 Gpc)3 comoving volume spanning five orders of magnitude in dynamical range. Here, we introduce the halo and galaxy catalogues built upon it, both in a wide (5000 deg2) and deep (z snapshots. Haloes were resolved down to few 1011 h-1 M⊙. This allowed us to model galaxies down to absolute magnitude Mr amplitude of poorly resolved haloes at the ≲5 per cent level, and their three-pt correlation function. We find a characteristic scale-dependent bias of ≲6 per cent across the BAO feature for haloes well above M⋆ ˜ 1012 h-1 M⊙ and for luminous red galaxy like galaxies. For haloes well below M⋆ the scale dependence at 100 h-1 Mpc is ≲2 per cent. Lastly, we discuss the validity of the large-scale Kaiser limit across redshift and departures from it towards non-linear scales. We make the current version of the lightcone halo and galaxy catalogue (MICECATv1.0) publicly available through a dedicated web portal to help develop and exploit the new generation of astronomical surveys.

  2. The ROCKSTAR Phase-space Temporal Halo Finder and the Velocity Offsets of Cluster Cores

    Science.gov (United States)

    Behroozi, Peter S.; Wechsler, Risa H.; Wu, Hao-Yi

    2013-01-01

    We present a new algorithm for identifying dark matter halos, substructure, and tidal features. The approach is based on adaptive hierarchical refinement of friends-of-friends groups in six phase-space dimensions and one time dimension, which allows for robust (grid-independent, shape-independent, and noise-resilient) tracking of substructure; as such, it is named ROCKSTAR (Robust Overdensity Calculation using K-Space Topologically Adaptive Refinement). Our method is massively parallel (up to 105 CPUs) and runs on the largest current simulations (>1010 particles) with high efficiency (10 CPU hours and 60 gigabytes of memory required per billion particles analyzed). A previous paper has shown ROCKSTAR to have excellent recovery of halo properties; we expand on these comparisons with more tests and higher-resolution simulations. We show a significant improvement in substructure recovery compared to several other halo finders and discuss the theoretical and practical limits of simulations in this regard. Finally, we present results that demonstrate conclusively that dark matter halo cores are not at rest relative to the halo bulk or substructure average velocities and have coherent velocity offsets across a wide range of halo masses and redshifts. For massive clusters, these offsets can be up to 350 km s-1 at z = 0 and even higher at high redshifts. Our implementation is publicly available at http://code.google.com/p/rockstar.

  3. Null Environmental Effects of the Cosmic Web on Dark Matter Halo Properties

    Science.gov (United States)

    Goh, Tze; Primack, Joel; Aragon-Calvo, Miguel; Hellinger, Doug; Rodriguez-Puebla, Aldo; Lee, Christoph; Eckleholm, Elliot; Johnston, Kathryn

    2018-01-01

    We study the effects of the cosmic web environment (filaments, voids and walls) and environmental density on key properties of dark matter halos at redshift z = 0 using the Bolshoi-Planck ΛCDM. The z=0 Bolshoi-Planck simulation is analysed into filaments, voids and walls using the SpineWeb method, as well as VIDE method, both of which use Voronoi tessellation and the watershed transform. The key halo properties that we study are the mass accretion rate, spin parameter, concentration, prolateness, scale factor of the last major merger, and scale factor when the halo had half of its z=0 mass. For all these properties, we find that there is no discernible difference between the halo properties in filaments, walls or voids when compared at the same environmental density. As a result, we conclude that environmental density is the core attribute that affects these properties. This conclusion is in line with recent findings that properties of galaxies in redshift surveys are independent of their cosmic web environment at the same environmental density. We also find that the local web environment of the Milky Way and the Andromeda galaxy near the centre of a cosmic wall does not appear to have any effect on the key properties of these galaxies' dark matter halos, although we find that it is rather rare to have such massive halos near the centre of a relatively small cosmic wall.

  4. Surface density of dark matter haloes on galactic and cluster scales

    Science.gov (United States)

    Del Popolo, A.; Cardone, V. F.; Belvedere, G.

    2013-02-01

    In this paper, we analysed the correlation between the central surface density and the halo core radius of galaxies, and cluster of galaxies dark matter (DM) haloes, in the framework of the secondary infall model. We used Del Popolo secondary infall model taking into account ordered and random angular momentum, dynamical friction and DM adiabatic contraction to calculate the density profile of haloes, and then these profiles are used to determine the surface density of DM haloes. The main result is that r* (the halo characteristic radius) is not a universal quantity as claimed by Donato et al. and Gentile et al. On the contrary, we find a correlation with the halo mass M200 in agreement with Cardone & Tortora, Boyarsky et al. and Napolitano, Romanowsky & Tortora, but with a significantly smaller scatter, namely 0.16 ± 0.05. We also consider the baryon column density finding this latter being indeed a constant for low-mass systems, such as dwarfs, but correlating with mass with a slope of α = 0.18 ± 0.05. In the case of the surface density of DM for a system composed only of DM, as in dissipationless simulations, we get α = 0.20 ± 0.05. These results leave little room for the recently claimed universality of (dark and stellar) column density.

  5. The Peculiar Behavior of Halo Coronal Mass Ejections in Solar Cycle 24

    Science.gov (United States)

    Gopalswamy, N.; Xie, H.; Akiyama, S.; Makela, P.; Yashiro, S.; Michalek, G.

    2015-01-01

    We report on the remarkable finding that the halo coronal mass ejections (CMEs) in cycle 24 are more abundant than in cycle 23, although the sunspot number in cycle 24 has dropped by approx. 40%. We also find that the distribution of halo-CME source locations is different in cycle 24: the longitude distribution of halos is much flatter with the number of halos originating at a central meridian distance greater than or equal to 60deg twice as large as that in cycle 23. On the other hand, the average speed and associated soft X-ray flare size are the same in both cycles, suggesting that the ambient medium into which the CMEs are ejected is significantly different. We suggest that both the higher abundance and larger central meridian longitudes of halo CMEs can be explained as a consequence of the diminished total pressure in the heliosphere in cycle 24. The reduced total pressure allows CMEs to expand more than usual making them appear as halos.

  6. Mapping stellar content to dark matter halos - III. Environmental dependence and conformity of galaxy colours

    Science.gov (United States)

    Zu, Ying; Mandelbaum, Rachel

    2018-02-01

    Recent studies suggest that the quenching properties of galaxies are correlated over several mega-parsecs. The large-scale "galactic conformity" phenomenon around central galaxies has been regarded as a potential signature of "galaxy assembly bias" or "pre-heating", both of which interpret conformity as a result of direct environmental effects acting on galaxy formation. Building on the iHOD halo quenching framework developed in Zu & Mandelbaum (2015, 2016), we discover that our fiducial halo mass quenching model, without any galaxy assembly bias, can successfully explain the overall environmental dependence and the conformity of galaxy colours in SDSS, as measured by the mark correlation functions of galaxy colours and the red galaxy fractions around isolated primaries, respectively. Our fiducial iHOD halo quenching mock also correctly predicts the differences in the spatial clustering and galaxy-galaxy lensing signals between the more vs. less red galaxy subsamples, split by the red-sequence ridge-line at fixed stellar mass. Meanwhile, models that tie galaxy colours fully or partially to halo assembly bias have difficulties in matching all these observables simultaneously. Therefore, we demonstrate that the observed environmental dependence of galaxy colours can be naturally explained by the combination of 1) halo quenching and 2) the variation of halo mass function with environment — an indirect environmental effect mediated by two separate physical processes.

  7. Stellar disc truncations and extended haloes in face-on spiral galaxies

    Science.gov (United States)

    Peters, S. P. C.; van der Kruit, P. C.; Knapen, J. H.; Trujillo, I.; Fliri, J.; Cisternas, M.; Kelvin, L. S.

    2017-09-01

    We use data from the IAC Stripe82 Legacy Project to study the surface photometry of 22 nearby, face-on to moderately inclined spiral galaxies. The reprocessed and combined Stripe 82 g',r' and I' images allow us to probe the galaxy down to 29-30 r'-magnitudes arcsec-2 and thus reach into the very faint outskirts of the galaxies. Truncations are found in three galaxies. An additional 15 galaxies are found to have an apparent extended stellar halo. Simulations show that the scattering of light from the inner galaxy by the point spread function (PSF) can produce faint structures resembling haloes, but this effect is insufficient to fully explain the observed haloes. The presence of these haloes and of truncations is mutually exclusive, and we argue that the presence of a stellar halo and/or light scattered by the PSF can hide truncations. Furthermore, we find that the onset of the stellar halo and the truncations scales tightly with galaxy size. Interestingly, the fraction of light does not correlate with dynamic mass. Nineteen galaxies are found to have breaks in their profiles, the radius of which also correlates with galaxy size.

  8. The potential of isotopically enriched magnesium to study bone implant degradation in vivo.

    Science.gov (United States)

    Draxler, Johannes; Martinelli, Elisabeth; Weinberg, Annelie M; Zitek, Andreas; Irrgeher, Johanna; Meischel, Martin; Stanzl-Tschegg, Stefanie E; Mingler, Bernhard; Prohaska, Thomas

    2017-03-15

    This pilot study highlights the substantial potential of using isotopically enriched (non-radioactive) metals to study the fate of biodegradable metal implants. It was possible to show that magnesium (Mg) release can be observed by combining isotopic mass spectrometry and isotopic pattern deconvolution for data reduction, even at low amounts of Mg released a from slowly degrading (26)Mg enriched (>99%) Mg metal. Following implantation into rats, structural in vivo changes were monitored by μCT. Results showed that the applied Mg had an average degradation rate of 16±5μmyear(-1), which corresponds with the degradation rate of pure Mg. Bone and tissue extraction was performed 4, 24, and 52weeks after implantation. Bone cross sections were analyzed by laser ablation inductively coupled plasma mass spectrometry (ICP-MS) to determine the lateral (26)Mg distribution. The (26)Mg/(24)Mg ratios in digested tissue and excretion samples were analyzed by multi collector ICP-MS. Isotope pattern deconvolution in combination with ICP-MS enabled detection of Mg pin material in amounts as low as 200ppm in bone tissues and 20ppm in tissues up to two fold increased Mg levels with a contribution of pin-derived Mg of up to 75% (4weeks) and 30% (24weeks) were found adjacent to the implant. After complete degradation, no visual bone disturbance or residual pin-Mg could be detected in cortical bone. In organs, increased Δ(26)Mg/(24)Mg values up to 16‰ were determined compared to control samples. Increased Δ(26)Mg/(24)Mg values were detected in serum samples at a constant total Mg level. In contrast to urine, feces did not show a shift in the (26)Mg/(24)Mg ratios. This investigation showed that the organism is capable of handling excess Mg well and that bones fully recover after degradation. Magnesium alloys as bone implants have faced increasing attention over the past years. In vivo degradation and metabolism studies of these implant materials have shown the promising application

  9. Implementation of a 3D halo neutral model in the TRANSP code and application to projected NSTX-U plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Medley, S. S. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Liu, D. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Univ. of California, Irvine, CA (United States). Dept. of Physics and Astronomy; Gorelenkova, M. V. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Heidbrink, W. W. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Univ. of California, Irvine, CA (United States). Dept. of Physics and Astronomy; Stagner, L. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Univ. of California, Irvine, CA (United States). Dept. of Physics and Astronomy

    2016-01-12

    A 3D halo neutral code developed at the Princeton Plasma Physics Laboratory and implemented for analysis using the TRANSP code is applied to projected National Spherical Torus eXperiment-Upgrade (NSTX-U plasmas). The legacy TRANSP code did not handle halo neutrals properly since they were distributed over the plasma volume rather than remaining in the vicinity of the neutral beam footprint as is actually the case. The 3D halo neutral code uses a 'beam-in-a-box' model that encompasses both injected beam neutrals and resulting halo neutrals. Upon deposition by charge exchange, a subset of the full, one-half and one-third beam energy components produce first generation halo neutrals that are tracked through successive generations until an ionization event occurs or the descendant halos exit the box. The 3D halo neutral model and neutral particle analyzer (NPA) simulator in the TRANSP code have been benchmarked with the Fast-Ion D-Alpha simulation (FIDAsim) code, which provides Monte Carlo simulations of beam neutral injection, attenuation, halo generation, halo spatial diffusion, and photoemission processes. When using the same atomic physics database, TRANSP and FIDAsim simulations achieve excellent agreement on the spatial profile and magnitude of beam and halo neutral densities and the NPA energy spectrum. The simulations show that the halo neutral density can be comparable to the beam neutral density. These halo neutrals can double the NPA flux, but they have minor effects on the NPA energy spectrum shape. The TRANSP and FIDAsim simulations also suggest that the magnitudes of beam and halo neutral densities are relatively sensitive to the choice of the atomic physics databases.

  10. Weak Gravitational Lensing by Galaxies - Implications for Dark Matter Halos

    Science.gov (United States)

    Brainerd, T. G.; Blandford, R. D.; Smail, I.

    1996-05-01

    A detection of weak, tangential distortion of the images of cosmologically distant, faint galaxies caused by gravitational lensing by foreground galaxies is reported. The imaging data consist of a 24 ksec integration in Gunn-r of a single blank field obtained with the COSMIC imaging spectrograph on the Hale 5-m telescope. The orientations of faint (23 right > = 0.011 +/- 0.006 (95% confidence bounds) is found for the faint galaxies. The variation of right > with both differential lens-source separation and the maximum radius of the annulus is investigated. From Monte Carlo simulations of galaxy-galaxy lensing that incorporate measured properties of local galaxies and modest extrapolations of the observed redshift distribution of faint galaxies, formal best-fit parameters for the dark matter halos associated with the lens galaxies are obtained. For L(*) galaxies a characteristic circular velocity of V(*) ~ 220+/- 80 km/s and outer scale radius of s(*) >= 100h(-1) kpc is found. These parameters imply a typical mass for the lens galaxies within 100 h(-1) kpc of order 1.0(+1.2}_{-0.5) x 10(12) h(-1) M_sun (90% confidence bounds), in good agreement with recent dynamical estimates of the masses of local spiral galaxies

  11. The Halo surrounding native English speaker teachers in Indonesia

    Directory of Open Access Journals (Sweden)

    Angga Kramadibrata

    2016-01-01

    Full Text Available The Native Speaker Fallacy, a commonly held belief that Native English Speaker Teachers (NESTs are inherently better than Non-NESTs, has long been questioned by ELT researchers. However, this belief still stands strong in the general public. This research looks to understand how much a teacher’s nativeness affects a student’s attitude towards them, as well as the underlying reasons for their attitudes. Sixty seven respondents in two groups were asked to watch an animated teaching video, after which they completed a questionnaire that used Likert-scales to assess comprehensibility, clarity of explanation, engagement, and preference. The videos for both groups were identical apart from the narrator; one spoke in British English, while the other, Indian English. In addition, they were also visually identified as Caucasian and Asian, respectively. The video was controlled for speed of delivery. The quantitative data were then triangulated using qualitative data collected through open questions in the questionnaire as well as from a semi-structured interview conducted with 10 respondents. The data show that there is a significant implicit preference for NEST teachers in the video, as well as in respondent’s actual classes. However, when asked explicitly, respondents didn’t rank nativeness as a very important quality in English teachers. This discrepancy between implicit and explicit attitudes might be due to a subconscious cognitive bias, namely the Halo Effect, in which humans tend to make unjustified presumptions about a person based on known but irrelevant information.

  12. Proton transfer in acetylacetone and its α-halo derivatives.

    Science.gov (United States)

    Dolati, Fatemeh; Tayyari, Sayyed Faramarz; Vakili, Mohammad; Wang, Yan Alexander

    2016-01-07

    A two-dimensional potential energy surface was utilized to treat the proton transfer in acetylacetone (AA) and its α-halo derivatives: α-fluoro-(FAA), α-chloro-(ClAA), and α-bromo-acetylacetone (BrAA). This potential energy function, which couples O-H stretching and in-plane bending vibrations, was acquired through ab initio calculations for a fixed skeleton geometry. The resulting potential energy surfaces were then used to calculate the proton tunneling frequencies and proton transfer barrier heights. The barrier heights (the energy difference between the saddle point and the minima) calculated at the MP2/6-31G(2d,p) level of theory for proton transfers in AA, FAA, ClAA, and BrAA are 7.2, 9.4, 6.3, and 5.9 kcal mol(-1), respectively. The theoretically predicted proton transfer barrier heights exhibit excellent linear correlations with geometrical, electronic structural, and topological parameters evaluated by the atoms-in-molecule (AIM) and natural bond orbital (NBO) analyses.

  13. Halo bias in Lagrangian space: estimators and theoretical predictions

    Science.gov (United States)

    Modi, Chirag; Castorina, Emanuele; Seljak, Uroš

    2017-12-01

    We present several methods to accurately estimate Lagrangian bias parameters and substantiate them using simulations. In particular, we focus on the quadratic terms, both the local and the non-local ones, and show the first clear evidence for the latter in the simulations. Using Fourier space correlations, we also show for the first time, the scale dependence of the quadratic and non-local bias coefficients. For the linear bias, we fit for the scale dependence and demonstrate the validity of a consistency relation between linear bias parameters. Furthermore, we employ real-space estimators, using both cross-correlations and the peak-background split argument. This is the first time the latter is used to measure anisotropic bias coefficients. We find good agreement for all the parameters among these different methods, and also good agreement for local bias with Excursion set constraints τ theory predictions. We also try to exploit possible relations among the different bias parameters. Finally, we show how including higher order bias reduces the magnitude and scale dependence of stochasticity of the halo field.

  14. Isotope analytics for the evaluation of the feeding influence on the isotope ratio in beef samples; Isotopenanalytik zur Bestimmung des Einflusses der Ernaehrung auf die Isotopenzusammensetzung in Rinderproben

    Energy Technology Data Exchange (ETDEWEB)

    Herwig, Nadine

    2010-11-17

    Information about the origin of food and associated production systems has a high significance for food control. An extremely promising approach to obtain such information is the determination of isotope ratios of different elements. In this study the correlation of the isotope ratios C-13/C-12, N-15/N-14, Mg-25/Mg-24, and Sr-87/Sr-86 in bovine samples (milk and urine) and the corresponding isotope ratios in feed was investigated. It was shown that in the bovine samples all four isotope ratios correlate with the isotope composition of the feed. The isotope ratios of strontium and magnesium have the advantage that they directly reflect the isotope ratios of the ingested feed since there is no isotope fractionation in the bovine organism which is in contrast to the case of carbon and nitrogen isotope ratios. From the present feeding study it is evident, that a feed change leads to a significant change in the delta C-13 values in milk and urine within 10 days already. For the deltaN-15 values the feed change was only visible in the bovine urine after 49 days. Investigations of cows from two different regions (Berlin/Germany and Goestling/Austria) kept at different feeding regimes revealed no differences in the N-15/N-14 and Mg-26/Mg-24 isotope ratios. The strongest correlation between the isotope ratio of the bovine samples and the kind of ingested feed was observed for the carbon isotope ratio. With this ratio even smallest differences in the feed composition were traceable in the bovine samples. Since different regions usually coincide with different feeding regimes, carbon isotope ratios can be used to distinguish bovine samples from different regions if the delta C-13 values of the ingested feed are different. Furthermore, the determination of strontium isotope ratios revealed significant differences between bovine and feed samples of Berlin and Goestling due to the different geologic realities. Hence the carbon and strontium isotope ratios allow the best

  15. Mg II-Absorbing Galaxies in the UltraVISTA Survey

    Science.gov (United States)

    Stroupe, Darren; Lundgren, Britt

    2018-01-01

    Light that is emitted from distant quasars can become partially absorbed by intervening gaseous structures, including galaxies, in its path toward Earth, revealing information about the chemical content, degree of ionization, organization and evolution of these structures through time. In this project, quasar spectra are used to probe the halos of foreground galaxies at a mean redshift of z=1.1 in the COSMOS Field. Mg II absorption lines in Sloan Digital Sky Survey quasar spectra are paired with galaxies in the UltraVISTA catalog at an impact parameter less than 200 kpc. A sample of 77 strong Mg II absorbers with a rest-frame equivalent width ≥ 0.3 Å and redshift from 0.34 < z < 2.21 are investigated to find equivalent width ratios of Mg II, C IV and Fe II absorption lines, and their relation to the impact parameter and the star formation rates, stellar masses, environments and redshifts of their host galaxies.

  16. The halo mass function from the dark ages through the present day

    Science.gov (United States)

    Reed, Darren S.; Bower, Richard; Frenk, Carlos S.; Jenkins, Adrian; Theuns, Tom

    2007-01-01

    We use an array of high-resolution N-body simulations to determine the mass function of dark matter haloes at redshifts 10-30. We develop a new method for compensating for the effects of finite simulation volume that allows us to find an approximation to the true `global' mass function. By simulating a wide range of volumes at different mass resolution, we calculate the abundance of haloes of mass 105-12h-1Msolar. This enables us to predict accurately the abundance of the haloes that host the sources that reionize the Universe. In particular, we focus on the small mass haloes (>~105.5-6h-1Msolar) likely to harbour Population III stars where gas cools by molecular hydrogen emission, early galaxies in which baryons cool by atomic hydrogen emission at a virial temperature of ~104K (~107.5-8 h-1Msolar), and massive galaxies that may be observable at redshift ~10. When we combine our data with simulations that include high-mass haloes at low redshift, we find that the best fit to the halo mass function depends not only on the linear overdensity, as is commonly assumed in analytic models, but also on the slope of the linear power spectrum at the scale of the halo mass. The Press-Schechter model gives a poor fit to the halo mass function in the simulations at all epochs; the Sheth-Tormen model gives a better match, but still overpredicts the abundance of rare objects at all times by up to 50 per cent. Finally, we consider the consequences of the recently released WMAP 3-yr cosmological parameters. These lead to much less structure at high redshift, reducing the number of z = 10 `mini-haloes' by more than a factor of two and the number of z = 30 galaxy hosts by nearly four orders of magnitude. Code to generate our best-fitting halo mass function may be downloaded from http://icc.dur.ac.uk/Research/PublicDownloads/genmf_readme.html.

  17. Transportation of medical isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Nielsen, D.L.

    1997-11-19

    A Draft Technical Information Document (HNF-1855) is being prepared to evaluate proposed interim tritium and medical isotope production at the Fast Flux Test Facility (FFTF). This assessment examines the potential health and safety impacts of transportation operations associated with the production of medical isotopes. Incident-free and accidental impacts are assessed using bounding source terms for the shipment of nonradiological target materials to the Hanford Site, the shipment of irradiated targets from the FFTF to the 325 Building, and the shipment of medical isotope products from the 325 Building to medical distributors. The health and safety consequences to workers and the public from the incident-free transportation of targets and isotope products would be within acceptable levels. For transportation accidents, risks to works and the public also would be within acceptable levels. This assessment is based on best information available at this time. As the medical isotope program matures, this analysis will be revised, if necessary, to support development of a final revision to the Technical Information Document.

  18. Connecting massive galaxies to dark matter haloes in BOSS - I. Is galaxy colour a stochastic process in high-mass haloes?

    Science.gov (United States)

    Saito, Shun; Leauthaud, Alexie; Hearin, Andrew P.; Bundy, Kevin; Zentner, Andrew R.; Behroozi, Peter S.; Reid, Beth A.; Sinha, Manodeep; Coupon, Jean; Tinker, Jeremy L.; White, Martin; Schneider, Donald P.

    2016-08-01

    We use subhalo abundance matching (SHAM) to model the stellar mass function (SMF) and clustering of the Baryon Oscillation Spectroscopic Survey (BOSS) `CMASS' sample at z ˜ 0.5. We introduce a novel method which accounts for the stellar mass incompleteness of CMASS as a function of redshift, and produce CMASS mock catalogues which include selection effects, reproduce the overall SMF, the projected two-point correlation function wp, the CMASS dn/dz, and are made publicly available. We study the effects of assembly bias above collapse mass in the context of `age matching' and show that these effects are markedly different compared to the ones explored by Hearin et al. at lower stellar masses. We construct two models, one in which galaxy colour is stochastic (`AbM' model) as well as a model which contains assembly bias effects (`AgM' model). By confronting the redshift dependent clustering of CMASS with the predictions from our model, we argue that that galaxy colours are not a stochastic process in high-mass haloes. Our results suggest that the colours of galaxies in high-mass haloes are determined by other halo properties besides halo peak velocity and that assembly bias effects play an important role in determining the clustering properties of this sample.

  19. The radial velocity dispersion profile of the Galactic halo : constraining the density profile of the dark halo of the Milky Way

    NARCIS (Netherlands)

    Battaglia, G; Helmi, A; Morrison, H; Harding, P; Olszewski, EW; Mateo, M; Freeman, KC; Norris, J; Shectman, SA

    2005-01-01

    We have compiled a new sample of 240 halo objects with accurate distance and radial velocity measurements, including globular clusters, satellite galaxies, field blue horizontal branch (FHB) stars and red giant stars from the Spaghetti survey. The new data lead to a significant increase in the

  20. Isotope geochemistry. Biological signatures in clumped isotopes of O₂.

    Science.gov (United States)

    Yeung, Laurence Y; Ash, Jeanine L; Young, Edward D

    2015-04-24

    The abundances of molecules containing more than one rare isotope have been applied broadly to determine formation temperatures of natural materials. These applications of "clumped" isotopes rely on the assumption that isotope-exchange equilibrium is reached, or at least approached, during the formation of those materials. In a closed-system terrarium experiment, we demonstrate that biological oxygen (O2) cycling drives the clumped-isotope composition of O2 away from isotopic equilibrium. Our model of the system suggests that unique biological signatures are present in clumped isotopes of O2—and not formation temperatures. Photosynthetic O2 is depleted in (18)O(18)O and (17)O(18)O relative to a stochastic distribution of isotopes, unlike at equilibrium, where heavy-isotope pairs are enriched. Similar signatures may be widespread in nature, offering new tracers of biological and geochemical cycling. Copyright © 2015, American Association for the Advancement of Science.

  1. Magnesium isotope evidence for single stage formation of CB chondrules by colliding planetesimals

    DEFF Research Database (Denmark)

    Olsen, Mia Bjørg Stolberg; Schiller, Martin; Krot, Alexander N.

    2013-01-01

    , indicating substantial suppression of isotopic fractionation during evaporative loss of Mg, possibly due to evaporation at high Mg partial pressure. Thus, the Mg-isotope data of skeletal chondrules from HH237 are consistent with their origin as melts produced in the impact-generated plume of colliding...... planetesimals. The inferred μMg* value of -3.87 ± 0.93 ppm for the CB parent body is significantly lower than the bulk solar system value of 4.5 ± 1.1 ppm inferred from CI chondrites, suggesting that CB chondrites accreted material comprising an early formed Al-free component....

  2. Iron isotope systematics in planetary reservoirs

    Science.gov (United States)

    Sossi, Paolo A.; Nebel, Oliver; Foden, John

    2016-10-01

    Iron is the only polyvalent major element, and controls reduction-oxidation (redox) reactions in a host of geologic processes and reservoirs, from the mineral- to planetary-scale, on Earth and in space. Mass transfer of Fe is often accompanied by changes in bonding environment, meaning the resultant variation in bond-strength in crystals, liquids and gases induces stable isotope fractionation, even at high temperatures. In the absence of iron exchange, electron transfer can also affect iron's valence state and calculated oxygen fugacity (fO2), however its isotope composition remains unchanged. Thus, iron isotopes are a powerful tool to investigate processes that involve mass transfer, redox reactions and changes in bonding environment in planetary systems. Primitive chondritic meteorites show remarkable isotopic homogeneity, δ57 Fe = - 0.01 ± 0.01 ‰ (2SE), over a wide range of Fe/Mg vs Ni/Mg, a proxy for fO2 in the solar nebula. In chondrites, there are iron isotope differences between metal and silicates that become more pronounced at higher metamorphic grades. However, on a planetary scale, Mars and Vesta overlap with chondrites, preserving no trace of core formation or volatile depletion on these bodies. Upon assessment of pristine lherzolites, the Bulk Silicate Earth is heavier than chondrites (δ57 Fe = + 0.05 ± 0.01 ‰; 2SE), and similar to or slightly lighter than the Moon. That the mantles of some differentiated inner solar system bodies extend to heavier compositions (+ 0.2 ‰) than chondrites may principally result from volatile depletion either at a nebular or late accretion stage. Within terrestrial silicate reservoirs, iron isotopes provide insight into petrogenetic and geodynamic processes. Partial melting of the upper mantle produces basalts that are heavier than their sources, scaling with degree of melting and driving the increasingly refractory peridotite to lighter compositions. Mid-Ocean Ridge Basalts (MORBs) are homogeneous to δ57 Fe

  3. Global properties of M31's stellar halo from the splash survey. II. Metallicity profile

    Energy Technology Data Exchange (ETDEWEB)

    Gilbert, Karoline M.; Kalirai, Jason S. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Guhathakurta, Puragra [UCO/Lick Observatory, Department of Astronomy and Astrophysics, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 (United States); Beaton, Rachael L.; Majewski, Steven R.; Patterson, Richard J. [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904-4325 (United States); Geha, Marla C.; Tollerud, Erik J. [Astronomy Department, Yale University, New Haven, CT 06520 (United States); Kirby, Evan N.; Bullock, James S. [California Institute of Technology, 1200 East California Boulevard, MC 249-17, Pasadena, CA 91125 (United States); Tanaka, Mikito; Chiba, Masashi, E-mail: kgilbert@stsci.edu [Astronomical Institute, Tohoku University, Aoba-ku, Sendai 980-8578 (Japan)

    2014-12-01

    We present the metallicity distribution of red giant branch (RGB) stars in M31's stellar halo, derived from photometric metallicity estimates for over 1500 spectroscopically confirmed RGB halo stars. The stellar sample comes from 38 halo fields observed with the Keck/DEIMOS spectrograph, ranging from 9 to 175 kpc in projected distance from M31's center, and includes 52 confirmed M31 halo stars beyond 100 kpc. While a wide range of metallicities is seen throughout the halo, the metal-rich peak of the metallicity distribution function becomes significantly less prominent with increasing radius. The metallicity profile of M31's stellar halo shows a continuous gradient from 9 to ∼100 kpc, with a magnitude of ∼ – 0.01 dex kpc{sup –1}. The stellar velocity distributions in each field are used to identify stars that are likely associated with tidal debris features. The removal of tidal debris features does not significantly alter the metallicity gradient in M31's halo: a gradient is maintained in fields spanning 10-90 kpc. We analyze the halo metallicity profile, as well as the relative metallicities of stars associated with tidal debris features and the underlying halo population, in the context of current simulations of stellar halo formation. We argue that the large-scale gradient in M31's halo implies M31 accreted at least one relatively massive progenitor in the past, while the field to field variation seen in the metallicity profile indicates that multiple smaller progenitors are likely to have contributed substantially to M31's outer halo.

  4. Reconstructing the Accretion History of the Galactic Stellar Halo from Chemical Abundance Ratio Distributions

    Science.gov (United States)

    Lee, Duane M.; Johnston, Kathryn V.; Sen, Bodhisattva; Jessop, Will

    2015-03-01

    Observational studies of halo stars during the past two decades have placed some limits on the quantity and nature of accreted dwarf galaxy contributions to the Milky Way (MW) stellar halo by typically utilizing stellar phase-space information to identify the most recent halo accretion events. In this study we tested the prospects of using 2D chemical abundance ratio distributions (CARDs) found in stars of the stellar halo to determine its formation history. First, we used simulated data from 11 “MW-like” halos to generate satellite template sets (STSs) of 2D CARDs of accreted dwarf satellites, which are composed of accreted dwarfs from various mass regimes and epochs of accretion. Next, we randomly drew samples of ˜103-4 mock observations of stellar chemical abundance ratios ([α/Fe], [Fe/H]) from those 11 halos to generate samples of the underlying densities for our CARDs to be compared to our templates in our analysis. Finally, we used the expectation-maximization algorithm to derive accretion histories in relation to the STS used and the sample size. For certain STSs used we typically can identify the relative mass contributions of all accreted satellites to within a factor of two. We also find that this method is particularly sensitive to older accretion events involving low-luminosity dwarfs, e.g., ultra-faint dwarfs—precisely those events that are too ancient to be seen by phase-space studies of stars and too faint to be seen by high-z studies of the early universe. Since our results only exploit two chemical dimensions and near-future surveys promise to provide ˜6-9 dimensions, we conclude that these new high-resolution spectroscopic surveys of the stellar halo will allow us to recover its accretion history—and the luminosity function of infalling dwarf galaxies—across cosmic time.

  5. Angular momentum evolution in dark matter haloes: a study of the Bolshoi and Millennium simulations

    Science.gov (United States)

    Contreras, S.; Padilla, N.; Lagos, C. D. P.

    2017-12-01

    We use three different cosmological dark matter simulations to study how the orientation of the angular momentum (AM) vector in dark matter haloes evolve with time. We find that haloes in this kind of simulations are constantly affected by a spurious change of mass, which translates into an artificial change in the orientation of the AM. After removing the haloes affected by artificial mass change, we found that the change in the orientation of the AM vector is correlated with time. The change in its angle and direction (I.e. the angle subtended by the AM vector in two consecutive time-steps) that affect the AM vector has a dependence on the change of mass that affects a halo, the time elapsed in which the change of mass occurs and the halo mass. We create a Monte Carlo simulation that reproduces the change of angle and direction of the AM vector. We reproduce the angular separation of the AM vector since a lookback time of 8.5 Gyr to today (α) with an accuracy of approximately 0.05 in cos(α). We are releasing this Monte Carlo simulation together with this publication. We also create a Monte Carlo simulation that reproduces the change of the AM modulus. We find that haloes in denser environments display the most dramatic evolution in their AM direction, as well as haloes with a lower specific AM modulus. These relations could be used to improve the way we follow the AM vector in low-resolution simulations.

  6. RECONSTRUCTING THE ACCRETION HISTORY OF THE GALACTIC STELLAR HALO FROM CHEMICAL ABUNDANCE RATIO DISTRIBUTIONS

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Duane M. [Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030 (China); Johnston, Kathryn V. [Department of Astronomy, Columbia University, New York City, NY 10027 (United States); Sen, Bodhisattva; Jessop, Will, E-mail: duane@shao.ac.cn [Department of Statistics, Columbia University, New York City, NY 10027 (United States)

    2015-03-20

    Observational studies of halo stars during the past two decades have placed some limits on the quantity and nature of accreted dwarf galaxy contributions to the Milky Way (MW) stellar halo by typically utilizing stellar phase-space information to identify the most recent halo accretion events. In this study we tested the prospects of using 2D chemical abundance ratio distributions (CARDs) found in stars of the stellar halo to determine its formation history. First, we used simulated data from 11 “MW-like” halos to generate satellite template sets (STSs) of 2D CARDs of accreted dwarf satellites, which are composed of accreted dwarfs from various mass regimes and epochs of accretion. Next, we randomly drew samples of ∼10{sup 3–4} mock observations of stellar chemical abundance ratios ([α/Fe], [Fe/H]) from those 11 halos to generate samples of the underlying densities for our CARDs to be compared to our templates in our analysis. Finally, we used the expectation-maximization algorithm to derive accretion histories in relation to the STS used and the sample size. For certain STSs used we typically can identify the relative mass contributions of all accreted satellites to within a factor of two. We also find that this method is particularly sensitive to older accretion events involving low-luminosity dwarfs, e.g., ultra-faint dwarfs—precisely those events that are too ancient to be seen by phase-space studies of stars and too faint to be seen by high-z studies of the early universe. Since our results only exploit two chemical dimensions and near-future surveys promise to provide ∼6–9 dimensions, we conclude that these new high-resolution spectroscopic surveys of the stellar halo will allow us to recover its accretion history—and the luminosity function of infalling dwarf galaxies—across cosmic time.

  7. The structure and assembly history of cluster-sized haloes in self-interacting dark matter

    Science.gov (United States)

    Brinckmann, Thejs; Zavala, Jesús; Rapetti, David; Hansen, Steen H.; Vogelsberger, Mark

    2018-02-01

    We perform dark-matter-only simulations of 28 relaxed massive cluster-sized haloes for cold dark matter (CDM) and self-interacting dark matter (SIDM) models, to study structural differences between the models at large radii, where the impact of baryonic physics is expected to be very limited. We find that the distributions for the radial profiles of the density, ellipsoidal axial ratios and velocity anisotropies (β) of the haloes differ considerably between the models (at the ˜1σ level), even at ≳ 10 per cent of the virial radius, if the self-scattering cross-section is σ/mχ = 1 cm2 g-1. Direct comparison with observationally inferred density profiles disfavours SIDM for σ/mχ = 1 cm2 g-1, but in an intermediate radial range ( ˜ 3 per cent of the virial radius), where the impact of baryonic physics is uncertain. At this level of the cross-section, we find a narrower β distribution in SIDM, clearly skewed towards isotropic orbits, with no SIDM (90 per cent of CDM) haloes having β > 0.12 at 7 per cent of the virial radius. We estimate that with an observational sample of ˜30 (˜1015 M⊙) relaxed clusters, β can potentially be used to put competitive constraints on SIDM, once observational uncertainties improve by a factor of a few. We study the suppression of the memory of halo assembly history in SIDM clusters. For σ/mχ = 1 cm2 g-1, we find that this happens only in the central halo regions (˜1/4 of the scale radius of the halo), and only for haloes that assembled their mass within this region earlier than a formation redshift zf ˜ 2. Otherwise, the memory of assembly remains and is reflected in ways similar to CDM, albeit with weaker trends.

  8. Galaxy Evolution with Stellar Disks, Halos, and Streams in Nearby Galaxies

    Science.gov (United States)

    Staudaher, Shawn M.

    This thesis begins with a deep-dive into the stellar properties of the nearby spiral galaxy, M 63, a member of the EDGES (Extended Disk Galaxy Exploration Science) survey. Deep ( 28 AB mag arcsec-2) 3.6 mum imaging from the Spitzer Space Telescope reveals that the spiral structure of this galaxy is enveloped by an extended stellar halo, the result of the accretion of smaller galaxies. The mass of this stellar halo agrees well with results from the latest large scale LambdaCDM based galaxy evolution models. M 63 is also host to a tidal stream, an actively accreting satellite. The mass of the progenitor satellite is large enough that only sixteen similarly sized accretion events would account for the mass in the stellar halo. In addition, the majority of satellite accretion must have happened in the past as the average accretion rate derived from the stellar halo is significantly larger than the average accretion rate derived from the more recent tidal stream. The scope of the thesis is then extended to include the full sample of 92 nearby galaxies from EDGES. This is the largest Spitzer Space Telescope survey to probe the extended stellar properties of nearby galaxies. The surface brightness profiles of EDGES galaxies contain an unprecedented number of breaks (transitions from one galactic component to the next) given the sample size of EDGES, proving that studies of break statistics are incomplete without significantly deep imaging. The surface brightness profiles are decomposed into their individual components and the stellar mass for each component is measured. Seven galaxies contain strong evidence for the presence of stellar halos, and the masses of these halos agree with predictions from LambdaCDM based galaxy evolution models. However, the lack of stellar halos in general may be evidence that simulations continue to suffer from the so-called "missing satellite problem", where the number of satellite galaxies is overpredicted compared to observations.

  9. Angular momentum properties of haloes and their baryon content in the Illustris simulation

    Science.gov (United States)

    Zjupa, Jolanta; Springel, Volker

    2017-04-01

    The angular momentum properties of virialized dark matter haloes have been measured with good statistics in collisionless N-body simulations, but an equally accurate analysis of the baryonic spin is still missing. We employ the Illustris simulation suite, one of the first simulations of galaxy formation with full hydrodynamics that produces a realistic galaxy population in a sizeable volume, to quantify the baryonic spin properties for more than ˜320 000 haloes. We first compare the systematic differences between different spin parameter and halo definitions, and the impact of sample selection criteria on the derived properties. We confirm that dark-matter-only haloes exhibit a close to self-similar spin distribution in mass and redshift of lognormal form. However, the physics of galaxy formation radically changes the baryonic spin distribution. While the dark matter component remains largely unaffected, strong trends with mass and redshift appear for the spin of diffuse gas and the formed stellar component. With time, the baryons staying bound to the halo develop a misalignment of their spin vector with respect to dark matter, and increase their specific angular momentum by a factor of ˜1.3 in the non-radiative case and ˜1.8 in the full physics setup at z = 0. We show that this enhancement in baryonic spin can be explained by the combined effect of specific angular momentum transfer from dark matter on to gas during mergers and from feedback expelling low specific angular momentum gas from the halo. Our results challenge certain models for spin evolution and underline the significant changes induced by baryonic physics in the structure of haloes.

  10. Evidence for magnesium isotope heterogeneity in the solar protoplanetary disk

    DEFF Research Database (Denmark)

    Larsen, Kirsten Kolbjørn; Trinquier, Anne Marie-Pierre Emilie; Paton, Chad

    2011-01-01

    assumption that the canonical 26Al/27Al ratio of ~5 × 10-5 recorded by the oldest dated solids, calcium–aluminium-rich inclusions (CAIs), represents the initial abundance of 26 Al for the solar system as a whole. Here, we report high-precision Mg-isotope measurements of inner solar system solids, asteroids...

  11. Calcium and Titanium Isotope Fractionation in CAIS: Tracers of Condensation and Inheritance in the Early Solar Protoplanetary Disk

    Science.gov (United States)

    Simon, J. I.; Jordan, M. K.; Tappa, M. J.; Kohl, I. E.; Young, E. D.

    2016-01-01

    The chemical and isotopic compositions of calcium-aluminum-rich inclusions (CAIs) can be used to understand the conditions present in the protoplantary disk where they formed. The isotopic compositions of these early-formed nebular materials are largely controlled by chemical volatility. The isotopic effects of evaporation/sublimation, which are well explained by both theory and experimental work, lead to enrichments of the heavy isotopes that are often exhibited by the moderately refractory elements Mg and Si. Less well understood are the isotopic effects of condensation, which limits our ability to determine whether a CAI is a primary condensate and/or retains any evidence of its primordial formation history.

  12. Resolving the Disk-Halo Degeneracy using Planetary Nebulae

    Science.gov (United States)

    Aniyan, S.; Freeman, K. C.; Arnaboldi, M.; Gerhard, O.; Coccato, L.; Fabricius, M.; Kuijken, K.; Merrifield, M.

    2017-10-01

    The decomposition of the 21 cm rotation curve of galaxies into contribution from the disk and dark halo depends on the adopted mass to light ratio (M/L) of the disk. Given the vertical velocity dispersion (σ z ) of stars in the disk and its scale height (h z ), the disk surface density and hence the M/L can be estimated. Earlier works have used this technique to conclude that galaxy disks are submaximal. Here we address an important conceptual problem: star-forming spirals have an old (kinematically hot) disk population and a young cold disk population. Both of these populations contribute to the integrated light spectra from which σ z is measured. The measured scale height h z is for the old disk population. In the Jeans equation, σ z and h z must pertain to the same population. We have developed techniques to extract the velocity dispersion of the old disk from integrated light spectra and from samples of planetary nebulae. We present the analysis of the disk kinematics of the galaxy NGC 628 using IFU data in the inner regions and planetary nebulae as tracers in the outer regions of the disk. We demonstrate that using the scale height of the old thin disk with the vertical velocity dispersion of the same population, traced by PNe, results in a maximal disk for NGC 628. Our analysis concludes that previous studies underestimate the disk surface mass density by ~ 2, sufficient to make a maximal disk for NGC 628 appear like a submaximal disk.

  13. An extremely primitive star in the Galactic halo.

    Science.gov (United States)

    Caffau, Elisabetta; Bonifacio, Piercarlo; François, Patrick; Sbordone, Luca; Monaco, Lorenzo; Spite, Monique; Spite, François; Ludwig, Hans-G; Cayrel, Roger; Zaggia, Simone; Hammer, François; Randich, Sofia; Molaro, Paolo; Hill, Vanessa

    2011-08-31

    The early Universe had a chemical composition consisting of hydrogen, helium and traces of lithium; almost all other elements were subsequently created in stars and supernovae. The mass fraction of elements more massive than helium, Z, is known as 'metallicity'. A number of very metal-poor stars has been found, some of which have a low iron abundance but are rich in carbon, nitrogen and oxygen. For theoretical reasons and because of an observed absence of stars with Z enriched above a critical value of Z, estimated to lie in the range 1.5 × 10(-8) to 1.5 × 10(-6) (ref. 8), although competing theories claiming the contrary do exist. (We use 'low-mass' here to mean a stellar mass of less than 0.8 solar masses, the stars that survive to the present day.) Here we report the chemical composition of a star in the Galactic halo with a very low Z (≤ 6.9 × 10(-7), which is 4.5 × 10(-5) times that of the Sun) and a chemical pattern typical of classical extremely metal-poor stars--that is, without enrichment of carbon, nitrogen and oxygen. This shows that low-mass stars can be formed at very low metallicity, that is, below the critical value of Z. Lithium is not detected, suggesting a low-metallicity extension of the previously observed trend in lithium depletion. Such lithium depletion implies that the stellar material must have experienced temperatures above two million kelvin in its history, given that this is necessary to destroy lithium.

  14. Lévy-Student distributions for halos in accelerator beams.

    Science.gov (United States)

    Cufaro Petroni, Nicola; De Martino, Salvatore; De Siena, Silvio; Illuminati, Fabrizio

    2005-12-01

    We describe the transverse beam distribution in particle accelerators within the controlled, stochastic dynamical scheme of stochastic mechanics (SM) which produces time reversal invariant diffusion processes. This leads to a linearized theory summarized in a Schrödinger-like (SL) equation. The space charge effects have been introduced in recent papers by coupling this S-L equation with the Maxwell equations. We analyze the space-charge effects to understand how the dynamics produces the actual beam distributions, and in particular we show how the stationary, self-consistent solutions are related to the (external and space-charge) potentials both when we suppose that the external field is harmonic (constant focusing), and when we a priori prescribe the shape of the stationary solution. We then proceed to discuss a few other ideas by introducing generalized Student distributions, namely, non-Gaussian, Lévy infinitely divisible (but not stable) distributions. We will discuss this idea from two different standpoints: (a) first by supposing that the stationary distribution of our (Wiener powered) SM model is a Student distribution; (b) by supposing that our model is based on a (non-Gaussian) Lévy process whose increments are Student distributed. We show that in the case (a) the longer tails of the power decay of the Student laws and in the case (b) the discontinuities of the Lévy-Student process can well account for the rare escape of particles from the beam core, and hence for the formation of a halo in intense beams.

  15. The interstellar halo of spiral galaxies: NGC 891

    Science.gov (United States)

    Kulkarni, Shrinivas R.; Rand, R. J.; Hester, J. Jeff

    1990-01-01

    Researchers have detected the Warm Ionized Medium (WIM) phase in the galaxy NGC 891. They found that the radial distribution of the WIM follows the molecular or young star distribution - an expected dependence. The amount of the WIM in this galaxy exceeds that in our Galaxy. The major surprize is the large thickness of the WIM phase - about 9 kpc instead 3 kpc as in our Galaxy. Clearly, this is the most significant result of the observations. The presence of low ionization gas at high z as well as at large galactocentric radii (where young stars are rare) is an important clue to the origin of the halo and observations such as the one reported here provide important data on this crucial question. In particular, the ionization of gas at high absolute z implies that either the UV photons manage to escape from the disk of the galaxy or that the extragalactic UV background plays an important role. The bulk of the WIM in spiral galaxies is a result of star-formation activity and thus these results can be understood by invoking a high star formation rate in NGC 891. Only the concerted action of supernovae can get the gas to the large z-heights as is observed in this galaxy. Support for this view comes from our detection of many worms i.e., bits and pieces of supershells in the form of kilo-parsec long vertical filaments. Researchers also saw a 600-pc size supershell located nearly one kpc above the plane of the galaxy.

  16. SDSS 1507+52: A Halo Cataclysmic Variable?

    Science.gov (United States)

    Patterson, Joseph; Thorstensen, John R.; Knigge, Christian

    2008-05-01

    We report a photometric and spectroscopic study of the peculiar cataclysmic variable SDSS 1507+52. The star shows very deep eclipses on the 67-minute orbital period, and those eclipses are easily separable into white-dwarf and hot-spot components. This leads to tight constraints on binary parameters, with M1 = 0.83(8) M⊙, M2 = 0.057(8) M⊙, R1 = 0.0097(9) R⊙, R2 = 0.097(4) R⊙, q = 0.069(2), and i = 83.18(13)°. Such numbers suggest possible membership among the WZ Sge stars, a common type of dwarf nova. The spectroscopic behavior (strong and broad H emission, double-peaked and showing a classic rotational disturbance during eclipse) is also typical. But the star’s orbital period is shockingly below the “period minimum” of ˜77 minutes that is characteristic of hydrogen-rich CVs; producing such a strange binary will require some tinkering with the theory of cataclysmic-variable evolution. The proper motion is also remarkably high for a star of its distance, which we estimate from photometry and trigonometric parallax as 230 ± 40 pc. This suggests a transverse velocity of 164 ± 30 km s-1 —uncomfortably high if the star belongs to a Galactic-disk population. These difficulties with understanding its evolution and space velocity can be solved if the star belongs to a Galactic-halo population. Based on observations obtained at the MDM Observatory, operated by Dartmouth College, Columbia University, Ohio State University, Ohio University, and the University of Michigan.

  17. Determining the Halo Mass Scale Where Galaxies Lose Their Gas

    Science.gov (United States)

    Rudnick, Gregory; Jablonka, Pascale; Moustakas, John; Aragón-Salamanca, Alfonso; Zaritsky, Dennis; Jaffé, Yara L.; De Lucia, Gabriella; Desai, Vandana; Halliday, Claire; Just, Dennis; Milvang-Jensen, Bo; Poggianti, Bianca

    2017-12-01

    A major question in galaxy formation is how the gas supply that fuels activity in galaxies is modulated by their environment. We use spectroscopy of a set of well-characterized clusters and groups at 0.4 10.4) of these old galaxies with weak [O II] emission. We use line ratios and compare to studies of local early-type galaxies to conclude that this gas is likely excited by post-AGB stars and hence represents a diffuse gas component in the galaxies. For cluster and group galaxies the fraction with EW([O II]) > 5 Å is f [O II] = {0.08}-0.02+0.03 and f [O II] = {0.06}-0.04+0.07, respectively. For field galaxies we find f [O II] = {0.27}-0.06+0.07, representing a 2.8σ difference between the [O II] fractions for old galaxies between the different environments. We conclude that a population of old galaxies in all environments has ionized gas that likely stems from stellar mass loss. In the field galaxies also experience gas accretion from the cosmic web, and in groups and clusters these galaxies have had their gas accretion shut off by their environment. Additionally, galaxies with emission preferentially avoid the virialized region of the cluster in position-velocity space. We discuss the implications of our results, among which is that gas accretion shutoff is likely effective at group halo masses (log { M }/{{ M }}⊙ > 12.8) and that there are likely multiple gas removal processes happening in dense environments. Based on observations obtained at the European Southern Observatory using the ESO Very Large Telescope on Cerro Paranal through ESO program 166.A-0162.

  18. Fractionation of silver isotopes in native silver explained by redox reactions

    Science.gov (United States)

    Mathur, Ryan; Arribas, Antonio; Megaw, Peter; Wilson, Marc; Stroup, Steven; Meyer-Arrivillaga, Danilo; Arribas, Isabel

    2018-03-01

    Scant data exist on the silver isotope composition of native silver specimens because of the relative newness of the technique. This study increases the published dataset by an order of magnitude and presents 80 silver new isotope analyses from native silver originating from a diverse set of worldwide deposits (8 deposit types, 33 mining districts in five continents). The measured isotopic range (defined as δ109Ag/107Ag in per mil units compared to NIST 978 Ag isotope standard) is +2.1 to -0.86‰ (2σ errors less than 0.015); with no apparent systematic correlations to date with deposit type or even within districts. Importantly, the data centering on 0‰ all come from high temperature hypogene/primary deposits whereas flanking and overlapping data represent secondary supergene deposits. To investigate the causes for the more fractionated values, several laboratory experiments involving oxidation of silver from natural specimens of Ag-rich sulfides and precipitation and adsorption of silver onto reagent grade MnO2 and FeOOH were conducted. Simple leach experiments demonstrate little Ag isotope fractionation occurred through oxidation of Ag from native Ag (Δsolution-native109Ag = 0.12‰). In contrast, significant fractionation occurred through precipitation of native Ag onto MnO2 (up to Δsolution-MnO2109Ag = 0.68‰, or 0.3amu). Adsorption of silver onto the MnO2 and FeOOH did not produce as large fractionation as precipitation (mean value of Δsolution-MnO2109Ag = 0.10‰). The most likely cause for the isotopic variations seen relates to redox effects such as the reduction of silver from Ag (I) to Ag° that occurs during precipitation onto the mineral surface. Since many Ag deposits have halos dominated by MnO2 and FeOOH phases, potential may exist for the silver isotope composition of ores and surrounding geochemical haloes to be used to better understand ore genesis and potential exploration applications. Aside from the Mn oxides, surface fluid silver

  19. Diffusion-driven magnesium and iron isotope fractionation in Hawaiian olivine

    Science.gov (United States)

    Teng, F.-Z.; Dauphas, N.; Helz, R.T.; Gao, S.; Huang, S.

    2011-01-01

    Diffusion plays an important role in Earth sciences to estimate the timescales of geological processes such as erosion, sediment burial, and magma cooling. In igneous systems, these diffusive processes are recorded in the form of crystal zoning. However, meaningful interpretation of these signatures is often hampered by the fact that they cannot be unambiguously ascribed to a single process (e.g., magmatic fractionation, diffusion limited transport in the crystal or in the liquid). Here we show that Mg and Fe isotope fractionations in olivine crystals can be used to trace diffusive processes in magmatic systems. Over sixty olivine fragments from Hawaiian basalts show isotopically fractionated Mg and Fe relative to basalts worldwide, with up to 0.4??? variation in 26Mg/24Mg ratios and 1.6??? variation in 56Fe/54Fe ratios. The linearly and negatively correlated Mg and Fe isotopic compositions [i.e., ??56Fe=(??3.3??0.3)????26Mg], co-variations of Mg and Fe isotopic compositions with Fe/Mg ratios of olivine fragments, and modeling results based on Mg and Fe elemental profiles demonstrate the coupled Mg and Fe isotope fractionation to be a manifestation of Mg-Fe inter-diffusion in zoned olivines during magmatic differentiation. This characteristic can be used to constrain the nature of mineral zoning in igneous and metamorphic rocks, and hence determine the residence times of crystals in magmas, the composition of primary melts, and the duration of metamorphic events. With improvements in methodology, in situ isotope mapping will become an essential tool of petrology to identify diffusion in crystals. ?? 2011 Elsevier B.V.

  20. Efficacy of brimonidine tartrate 0.2% ophthalmic solution in reducing halos after laser in situ keratomileusis.

    Science.gov (United States)

    Lee, Ji Hoon; You, Yong Sung; Choe, Chul Myong; Lee, Eun Suk

    2008-06-01

    To quantitatively evaluate the effect of brimonidine tartrate 0.2% (Alphagan) on halo and pupil size in patients who had symptomatic night-vision difficulties after laser in situ keratomileusis (LASIK). Nune Eye Hospital, Seoul, Korea. This study comprised 28 eyes of 14 patients with symptomatic night-vision difficulties after LASIK. Pupil diameter was measured with a Colvard pupillometer (Oasis Medical, Inc.). Quantitative analysis of halos was performed by measuring the area using a new computerized method. Pupil size and halo size were evaluated under scotopic and normal room light conditions. Alphagan was administered, and the effect was measured after 30 minutes and 1, 6, 12, and 24 hours. There was a statistically significant correlation between pupil size and halo size (r = 0.527; P<.0001; slope = 691.6 pixel/mm). Pupil size and halo size decreased significantly 30 minutes after Alphagan instillation under both luminance conditions (all P< .0001). Under normal room light, the pupil and halo remained decreased until the last measurement at 24 hours. Under scotopic conditions, the pupil returned to its preinstillation size at 24 hours while the halo remained decreased. The maximum effect on halos was observed after 6 hours, when the mean reduction over preinstillation size was 28.2% and 29.1% under normal room light conditions and scotopic conditions, respectively. Alphagan effectively reduced halo size and pupil size in postoperative LASIK patients with night-vision symptoms.