174 research outputs found
Investigating organic aerosol loading in the remote marine environment
Aerosol loading in the marine environment is investigated using aerosol composition measurements from several research ship campaigns (ICEALOT, MAP, RHaMBLe, VOCALS and OOMPH), observations of total AOD column from satellite (MODIS) and ship-based instruments (Maritime Aerosol Network, MAN), and a global chemical transport model (GEOS-Chem). This work represents the most comprehensive evaluation of oceanic OM emission inventories to date, by employing aerosol composition measurements obtained from campaigns with wide spatial and temporal coverage. The model underestimates AOD over the remote ocean on average by 0.02 (21 %), compared to satellite observations, but provides an unbiased simulation of ground-based Maritime Aerosol Network (MAN) observations. Comparison with cruise data demonstrates that the GEOS-Chem simulation of marine sulfate, with the mean observed values ranging between 0.22 μg m−3 and 1.34 μg m−3, is generally unbiased, however surface organic matter (OM) concentrations, with the mean observed concentrations between 0.07 μg m−3 and 0.77 μg m−3, are underestimated by a factor of 2–5 for the standard model run. Addition of a sub-micron marine OM source of approximately 9 TgC yr−1 brings the model into agreement with the ship-based measurements, however this additional OM source does not explain the model underestimate of marine AOD. The model underestimate of marine AOD is therefore likely the result of a combination of satellite retrieval bias and a missing marine aerosol source (which exhibits a different spatial pattern than existing aerosol in the model)
The UA9 experimental layout
The UA9 experimental equipment was installed in the CERN-SPS in March '09
with the aim of investigating crystal assisted collimation in coasting mode.
Its basic layout comprises silicon bent crystals acting as primary
collimators mounted inside two vacuum vessels. A movable 60 cm long block of
tungsten located downstream at about 90 degrees phase advance intercepts the
deflected beam.
Scintillators, Gas Electron Multiplier chambers and other beam loss monitors
measure nuclear loss rates induced by the interaction of the beam halo in the
crystal. Roman pots are installed in the path of the deflected particles and
are equipped with a Medipix detector to reconstruct the transverse distribution
of the impinging beam. Finally UA9 takes advantage of an LHC-collimator
prototype installed close to the Roman pot to help in setting the beam
conditions and to analyze the efficiency to deflect the beam. This paper
describes in details the hardware installed to study the crystal collimation
during 2010.Comment: 15pages, 11 figure, submitted to JINS
Observation of focusing of 400 GeV/c proton beam with the help of bent crystals
The results of observation and studies of focusing of 400 GeV/ c proton beam with the help of bent single crystals are presented. Two silicon crystals have been used in the measurements. The focal length of the first and second crystals is found to be 1.48 m and 0.68 m, respectively. The mean square size of the horizontal profile in the focus was 3.1 and 4.3 times as small as at the exit of the crystals
High-efficiency deflection of high energy protons due to channeling along the (110) axis of a bent silicon crystal
A deflection efficiency of about 61% was observed for 400 GeV/c protons due to channeling, most strongly along the 〈110〉 axis of a bent silicon crystal. It is comparable with the deflection efficiency in planar channeling and considerably larger than in the case of the 〈111〉 axis. The measured probability of inelastic nuclear interactions of protons in channeling along the 〈110〉 axis is only about 10% of its amorphous level whereas in channeling along the (110) planes it is about 25%. High efficiency deflection and small beam losses make this axial orientation of a silicon crystal a useful tool for the beam steering of high energy charged particles
Deflection of high-energy negative particles in a bent crystal through axial channeling and multiple volume reflection stimulated by doughnut scattering
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Double volume reflection of a proton beam by a sequence of two bent crystals
The doubling of the angle of beam deflection due to volume reflection of protons by a sequence of two bent silicon crystals was experimentally observed at the 400 GeV proton beam of the CERN SPS. A similar sequence of short bent crystals can be used as an efficient primary collimator for the Large Hadron Collider
Multiple Redox Modes in the Reversible Lithiation of High-Capacity, Peierls-Distorted Vanadium Sulfide.
This is the author accepted manuscript. The final version is available from ACS via http://dx.doi.org/10.1021/jacs.5b03395Vanadium sulfide VS4 in the patronite mineral structure is a linear chain compound comprising vanadium atoms coordinated by disulfide anions [S2](2-). (51)V NMR shows that the material, despite having V formally in the d(1) configuration, is diamagnetic, suggesting potential dimerization through metal-metal bonding associated with a Peierls distortion of the linear chains. This is supported by density functional calculations, and is also consistent with the observed alternation in V-V distances of 2.8 and 3.2 Å along the chains. Partial lithiation results in reduction of the disulfide ions to sulfide S(2-), via an internal redox process whereby an electron from V(4+) is transferred to [S2](2-) resulting in oxidation of V(4+) to V(5+) and reduction of the [S2](2-) to S(2-) to form Li3VS4 containing tetrahedral [VS4](3-) anions. On further lithiation this is followed by reduction of the V(5+) in Li3VS4 to form Li3+xVS4 (x = 0.5-1), a mixed valent V(4+)/V(5+) compound. Eventually reduction to Li2S plus elemental V occurs. Despite the complex redox processes involving both the cation and the anion occurring in this material, the system is found to be partially reversible between 0 and 3 V. The unusual redox processes in this system are elucidated using a suite of short-range characterization tools including (51)V nuclear magnetic resonance spectroscopy (NMR), S K-edge X-ray absorption near edge spectroscopy (XANES), and pair distribution function (PDF) analysis of X-ray data.SB acknowledges Schlumberger Stichting Fund and European Research Council (EU ERC) for funding. JC thanks BK21 plus project of Korea. We thank Phoebe Allan and Andrew J. Morris, University of Cambridge, for useful discussions. We also thank Trudy Bolin and Tianpin Wu of Beamline 9-BM, Argonne National Laboratory for help with XANES measurements. The DFT calculations were performed at the UCSB Center for Scientific Computing at UC Santa Barbara, supported by the California Nanosystems Institute (NSF CNS-0960316), Hewlett-Packard, and the Materials Research Laboratory (DMR-1121053). This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357
Analysis on the Issue of East Financial Integration
在1997年金融危机发生后,东亚各国和地区意识到过分依赖外国的资金存在着巨大的风险。因此,为了避免对外国资金的过分依赖防止危机再次发生,东亚各国和地区通过完善金融体系,加强金融合作以推进金融一体化。 在此背景下,本文对东亚金融的一体化程度做出分析。本文对东亚各国和地区金融一体化的必要前提:东亚货币金融合作,东亚各国和地区资本市场放松管制情况、各国和地区的资本流动以及各国和地区股票及债券市场的发展进行了定性分析和描述,同时对各国投资与储蓄的相关性、各国消费者通过金融市场分散风险的程度、各国股票市场以及各国债券市场与两大国际市场间的联系,对东亚各国和地区金融市场一体化程度进行了实证分析。本文的研...East Asia has realized that it has great risk to depend on the foreign capital, after 1997 financial crisis. East Asia tried to improve the financial system and strengthen financial cooperation, so as to avoid the recurrence of financial crisis. This thesis tries to address the issue of the financial integration of East Asia. First of all, the basis of financial integration of East Asia was anal...学位:经济学博士院系专业:经济学院国际贸易系_世界经济学号:2005140292
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