13,812,868 research outputs found
Halite and stable chlorine isotopes in the Zag H3-6 breccia
Zag is an H3-6 chondrite regolith breccia within which we have studied 14 halite grains ?3mm. The purity of the associated NaCl-H2O brine is implied by freezing characteristics of fluid inclusions in the halite and EPMA analyses together with a lack of other evaporite-like phases in the Zag H3-6 component. This is inconsistent with multistage evolution of the fluid involving scavenging of cations in the Zag region of the parent body. We suggest that the halite grains are clastic and did not crystallise in situ. Halite and water-soluble extracts from Zag have light Cl isotopic compositions, ?37-Cl = -1.4 to '2.8 ĂŻÂżÂœ. Previously reported bulk carbonaceous chondrite values are approximately ?37-Cl = +3 to +4 ĂŻÂżÂœ. This difference is too great to be the result of fractionation during evaporation and instead we suggest that Cl isotopes in chondrites are fractionated between a light reservoir associated with fluids and a heavier reservoir associated with higher temperature phases such as phosphates and silicates. Extraterrestrial carbon released at 600 degrees Celsius from the H3-4 matrix has ?13-C = -20 ĂŻÂżÂœ, consistent with poorly graphitised material being introduced into the matrix rather than indigenous carbonate derived from a brine. We have also examined 28 other H-chondrite falls in order to ascertain how widespread halite or evaporite-like mineral assemblages are in ordinary chondrites. We did not find any more to add to Zag (H3-6) and Monahans (H5), which suggests that such highly soluble phases were not usually preserved on the parent bodies
The Making of the Standard Model
This is the edited text of a talk given at CERN on Septembr 16, 2003, as part
of a celebration of the 30th anniversary of the discovery of neutral currents
and the 20th anniversary of the discovery of the W and Z particles.Comment: 21 page
Two-pion Bose-Einstein correlations in central Pb-Pb collisions at = 2.76 TeV
The first measurement of two-pion Bose-Einstein correlations in central Pb-Pb
collisions at TeV at the Large Hadron Collider is
presented. We observe a growing trend with energy now not only for the
longitudinal and the outward but also for the sideward pion source radius. The
pion homogeneity volume and the decoupling time are significantly larger than
those measured at RHIC.Comment: 17 pages, 5 captioned figures, 1 table, authors from page 12,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/388
Accurate spectroscopy of Sr atoms
We report the frequency measurement with an accuracy in the 100 kHz range of
several optical transitions of atomic Sr : at 689 nm, at 688 nm and at 679 nm. Measurements are performed with
a frequency chain based on a femtosecond laser referenced to primary frequency
standards. They allowed the indirect determination with a 70 kHz uncertainty of
the frequency of the doubly forbidden 5s^2^1S_0- 5s5p^3P_0 transition of
Sr at 698 nm and in a second step its direct observation. Frequency
measurements are performed for Sr and Sr, allowing the
determination of , and isotope shifts, as well as the
hyperfine constants.Comment: 12 pages, 16 figure
Phenomenological analysis connecting proton-proton and antiproton-proton elastic scattering
Based on the behavior of the elastic scattering data, we introduce an almost
model-independent parametrization for the imaginary part of the scattering
amplitude, with the energy and momentum transfer dependences inferred on
empirical basis and selected by rigorous theorems and bounds from axiomatic
quantum field theory. The corresponding real part is analytically evaluated by
means of dispersion relations, allowing connections between particle-particle
and particle-antiparticle scattering. Simultaneous fits to proton-proton and
antiproton-proton experimental data in the forward direction and also including
data beyond the forward direction, lead to a predictive formalism in both
energy and momentum transfer. We compare our extrapolations with predictions
from some popular models and discuss the applicability of the results in the
normalization of elastic rates that can be extracted from present and future
accelerator experiments (Tevatron, RHIC and LHC).Comment: 17 pages, 17 figures, to appear in Eur. Phys. J.
Suppression of charged particle production at large transverse momentum in central Pb-Pb collisions at TeV
Inclusive transverse momentum spectra of primary charged particles in Pb-Pb
collisions at = 2.76 TeV have been measured by the ALICE
Collaboration at the LHC. The data are presented for central and peripheral
collisions, corresponding to 0-5% and 70-80% of the hadronic Pb-Pb cross
section. The measured charged particle spectra in and GeV/ are compared to the expectation in pp collisions at the same
, scaled by the number of underlying nucleon-nucleon
collisions. The comparison is expressed in terms of the nuclear modification
factor . The result indicates only weak medium effects ( 0.7) in peripheral collisions. In central collisions,
reaches a minimum of about 0.14 at -7GeV/ and increases
significantly at larger . The measured suppression of high- particles is stronger than that observed at lower collision energies,
indicating that a very dense medium is formed in central Pb-Pb collisions at
the LHC.Comment: 15 pages, 5 captioned figures, 3 tables, authors from page 10,
published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/98
Integrable spin-boson interaction in the Tavis-Cummings model from a generic boundary twist
We construct models describing interaction between a spin and a single
bosonic mode using a quantum inverse scattering procedure. The boundary
conditions are generically twisted by generic matrices with both diagonal and
off-diagonal entries. The exact solution is obtained by mapping the transfer
matrix of the spin-boson system to an auxiliary problem of a spin- coupled
to the spin- with general twist of the boundary condition. The corresponding
auxiliary transfer matrix is diagonalized by a variation of the method of
-matrices of Baxter. The exact solution of our problem is obtained applying
certain large- limit to , transforming it into the bosonic algebra.Comment: 6 pages, revtex; 1 figure. To be published in EPJ
âOtherâ or âone of usâ?: the porn user in public and academic discourse
The consumption of sexually explicit media has long been a matter of public and political concern. It has also been a topic of academic interest. In both these arenas a predominantly behaviourist model of effects and regulation has worked to cast the examination of sexually explicit texts and their consumption as a debate about harm. The broader area of investigation remains extraordinarily undeveloped.
Sexually explicit media is a focus of interest for academics because of the way it âspeaksâ sex and sexuality for its culture. In this paper I examine existing and emerging figures of the porn consumer, their relation to ways of thinking and speaking about pornography, and the implications of these for future work on porn consumption.
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Identification of individual demands from market data under uncertainty
We show that, even under incomplete markets, the equilibrium manifold identifies individual demands everywhere in their domains. Under partial observation of the manifold, we determine maximal subsets of the domains on which identification holds. For this, we assume conditions of smoothness, interiority and regularity. It is crucial that there be date-zero consumption. As a by-product, we develop some duality theory under incomplete markets
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