804 research outputs found

    Neogene history of fluvial to shallow marine successions in the Kendari Basin, SE Sulawesi, Indonesia

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    Collision between Australia and SE Asia began in Sulawesi, the world's eleventh-largest island, in the Early Miocene and subsequently Neogene sediments were deposited largely in coastal to shelf environments throughout the island. These sediments have been assigned to the Celebes Molasse, previously considered as a single post-orogenic unit deposited unconformably on pre-Neogene sedimentary, metamorphic and ophiolitic rocks. The most complete and extensive sequences of Neogene sediments are in the Kendari Basin, situated at the southern end of the SE Arm of Sulawesi, where an outcrop-based sedimentological study was undertaken to interpret depositional environments, palaeogeography and stratigraphy. The oldest Neogene sediments are shallow marine carbonates and deltaic siliciclastics of the Bungku Formation. They are unconformably overlain by the Upper Miocene Pandua Formation which consists of sediments deposited in a variety of environments including braided river channels, fluvio-tidal channels, tidal flats, mouth bar complex and shoreface deposits. A Mio-Pliocene subaerial unconformity separates the marginal marine serpentinite-rich sediments of the Pandua Formation from the overlying fluviatile quartz-rich Langkowala Formation. The sediments of the lower part of the Langkowala Formation include conglomeratic channel fill, while the sediments of the upper part are transgressive deposits decreasing in maximum grain-size, marked by a reduction in channel/overbank ratio and increasing tidal influence. The transgressive Pliocene Eemoiko Formation is characterised by transgressive lags or onlap shell beds and deposits of a landwards-backstepping carbonate platform. The improved understanding of the Kendari Basin will aid the interpretation of the sedimentation history of frontier basins surrounding SE Sulawesi, many of which have not yet been drilled

    Radiation resistant optical fiber for FBG based sensing

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    Radiation-resistant optical fibers have been fabricated through MCVD process. The low radiation-induced-absorption in the fiber and few picometer shifting of Bragg-wavelength of the FBG under γ-exposure indicate its potential application for sensing in radiation environment

    Precision Measurement of the Boron to Carbon Flux Ratio in Cosmic Rays from 1.9 GV to 2.6 TV with the Alpha Magnetic Spectrometer on the International Space Station

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    Knowledge of the rigidity dependence of the boron to carbon flux ratio (B/C) is important in understanding the propagation of cosmic rays. The precise measurement of the B/C ratio from 1.9 GV to 2.6 TV, based on 2.3 million boron and 8.3 million carbon nuclei collected by AMS during the first 5 years of operation, is presented. The detailed variation with rigidity of the B/C spectral index is reported for the first time. The B/C ratio does not show any significant structures in contrast to many cosmic ray models that require such structures at high rigidities. Remarkably, above 65 GV, the B/C ratio is well described by a single power law RΔ with index Δ=-0.333±0.014(fit)±0.005(syst), in good agreement with the Kolmogorov theory of turbulence which predicts Δ=-1/3 asymptotically.Peer Reviewe

    Precision Measurement of the Helium Flux in Primary Cosmic Rays of Rigidities 1.9 GV to 3 TV with the Alpha Magnetic Spectrometer on the International Space Station

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    Knowledge of the precise rigidity dependence of the helium flux is important in understanding the origin, acceleration, and propagation of cosmic rays. A precise measurement of the helium flux in primary cosmic rays with rigidity (momentum/charge) from 1.9 GV to 3 TV based on 50 million events is presented and compared to the proton flux. The detailed variation with rigidity of the helium flux spectral index is presented for the first time. The spectral index progressively hardens at rigidities larger than 100 GV. The rigidity dependence of the helium flux spectral index is similar to that of the proton spectral index though the magnitudes are different. Remarkably, the spectral index of the proton to helium flux ratio increases with rigidity up to 45 GV and then becomes constant; the flux ratio above 45 GV is well described by a single power law.Peer Reviewe

    Antiproton Flux, Antiproton-to-Proton Flux Ratio, and Properties of Elementary Particle Fluxes in Primary Cosmic Rays Measured with the Alpha Magnetic Spectrometer on the International Space Station

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    A precision measurement by AMS of the antiproton flux and the antiproton-to-proton flux ratio in primary cosmic rays in the absolute rigidity range from 1 to 450 GV is presented based on 3.49×105 antiproton events and 2.42×109 proton events. The fluxes and flux ratios of charged elementary particles in cosmic rays are also presented. In the absolute rigidity range ∼60 to ∼500  GV, the antiproton p¯, proton p, and positron e+ fluxes are found to have nearly identical rigidity dependence and the electron e− flux exhibits a different rigidity dependence. Below 60 GV, the (p¯/p), (p¯/e+), and (p/e+) flux ratios each reaches a maximum. From ∼60 to ∼500  GV, the (p¯/p), (p¯/e+), and (p/e+) flux ratios show no rigidity dependence. These are new observations of the properties of elementary particles in the cosmos.Peer Reviewe

    Precision Measurement of the Proton Flux in Primary Cosmic Rays from Rigidity 1 GV to 1.8 TV with the Alpha Magnetic Spectrometer on the International Space Station

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    A precise measurement of the proton flux in primary cosmic rays with rigidity (momentum/charge) from 1 GV to 1.8 TV is presented based on 300 million events. Knowledge of the rigidity dependence of the proton flux is important in understanding the origin, acceleration, and propagation of cosmic rays. We present the detailed variation with rigidity of the flux spectral index for the first time. The spectral index progressively hardens at high rigidities.Peer Reviewe

    Fibre Bragg Grating Sensors for Radiation Insensitive Measurements

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    The response of fibre optic-based sensors exposed to gamma radiation is presented. This study shows that suitable fibre Bragg grating sensors exhibit a saturated radiation induced shift < 20 pm after 16 MRad of exposur

    Some model-independent phenomenological consequences of flexible brane worlds

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    In this work we will review the main properties of brane-world models with low tension. Starting from very general principles, it is possible to obtain an effective action for the relevant degrees of freedom at low energies (branons). Using the cross sections for high-energy processes involving branons, we set bounds on the different parameters appearing in these models. We also show that branons provide a WIMP candidate for dark matter in a natural way. We consider cosmological constraints on its thermal and non-thermal relic abundances. We derive direct detection limits and compare those limits with the preferred parameter region in the case in which the EGRET excess in the diffuse galactic gamma rays is due to dark matter annihilation. Finally we will discuss the constraints coming from the precision tests of the Standard Model and the muon anomalous magnetic moment.Comment: 10 pages, 6 figures. Contribution to the Proceedings of the Second International Conference on Quantum Theories and Renormalization Group in Gravity and Cosmology, IRGAC 2006, Barcelona, 11-15 July, 200

    Orbital and physical parameters of eclipsing binaries from the ASAS catalogue - IX. Spotted pairs with red giants

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    We present spectroscopic and photometric solutions for three spotted systems with red giant components. Absolute physical and orbital parameters for these double-lined detached eclipsing binary stars are presented for the first time. These were derived from the V-, and I-band ASAS and WASP photometry, and new radial velocities calculated from high quality optical spectra we obtained with a wide range of spectrographs and using the two-dimensional cross-correlation technique (TODCOR). All of the investigated systems (ASAS J184949-1518.7, BQ Aqr, and V1207 Cen) show the differential evolutionary phase of their components consisting of a main-sequence star or a subgiant and a red giant, and thus constitute very informative objects in terms of testing stellar evolution models. Additionally, the systems show significant chromospheric activity of both components. They can be also classified as classical RS CVn-type stars. Besides the standard analysis of radial velocities and photometry, we applied spectral disentangling to obtain separate spectra for both components of each analysed system which allowed for a more detailed spectroscopic study. We also compared the properties of red giant stars in binaries that show spots, with those that do not, and found that the activity phenomenon is substantially suppressed for stars with Rossby number higher than ∼1 and radii larger than ∼20 R⊙
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