710 research outputs found
Where do experiments end?
types: Editorial CommentCopyright © 2010 Elsevier. NOTICE: This is the author’s version of a work accepted for publication by Elsevier. Changes resulting from the publishing process, including peer review, editing, corrections, structural formatting and other quality control mechanisms, may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Geoforum, 2010, Vol. 41, Issue 5 pp. 667 – 670 DOI: 10.1016/j.geoforum.2010.05.003Editoria
Time-Dependent Hartree-Fock simulation of the expansion of abraded nuclei
A recent interpretation of the caloric curve based on the expansion of the
abraded spectator nucleus is re-analysed in the framework of the Time-Dependent
Hartree-Fock (TDHF) evolution. It is shown that the TDHF dynamics is more
complex than a single monopolar collective motion at moderate energy. The
inclusion of other important collective degrees of freedom may lead to the
dynamical creation of hollow structure. Then, low density regions could be
locally reached after a long time by the creation of these exotic density
profiles. In particular the systematic of the minimum density reached during
the expansion (the so-called turning points) appears to be different.Comment: 30 Latex pages including 9 figure
Geometrothermodynamics of black holes
The thermodynamics of black holes is reformulated within the context of the
recently developed formalism of geometrothermodynamics. This reformulation is
shown to be invariant with respect to Legendre transformations, and to allow
several equivalent representations. Legendre invariance allows us to explain a
series of contradictory results known in the literature from the use of
Weinhold's and Ruppeiner's thermodynamic metrics for black holes. For the
Reissner-Nordstr\"om black hole the geometry of the space of equilibrium states
is curved, showing a non trivial thermodynamic interaction, and the curvature
contains information about critical points and phase transitions. On the
contrary, for the Kerr black hole the geometry is flat and does not explain its
phase transition structure.Comment: Revised version, to be published in Gen.Rel.Grav.(Mashhoon's
Festschrift
Laboratory observations of enhanced entrainment in dense overflows in the presence of submarine canyons and ridges
Author Posting. © Elsevier B.V., 2008. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Deep Sea Research Part I: Oceanographic Research Papers 55 (2008): 737-750, doi:10.1016/j.dsr.2008.02.007.The continental slopes in the oceans are often covered by small-scale topographic
features such as submarine canyons and ridges. When dense plumes, flowing
geostrophically along the slope, encounter such features they may be steered downslope
inside and alongside the topography. A set of laboratory experiments was conducted at
the rotating Coriolis platform to investigate the effect of small-scale topography on plume
mixing. A dense water source was placed on top of a slope, and experiments were
repeated with three topographies: a smooth slope, a slope with a ridge, and a slope with a
canyon. Three flow regimes were studied: laminar, waves, and eddies. When a ridge or a
canyon were present on the slope, the dense plume was steered downslope and
instabilities developed along the ridge and canyon wall. This happened regardless of the
flow characteristics on the smooth slope. Froude and Reynolds numbers were estimated,
and were found to be higher for the topographically steered flow than for flow on smooth
topography. The stratification in the collecting basin was monitored and the mixing
inferred. The total mixing and the entrainment rate increased when a ridge or a canyon
were present. The difference in mixing levels between the regimes was smaller when
topography was present, indicating that it was the small-scale topography and not the
large-scale characteristics of the flow that determined the properties of the product water.AW was funded by the Swedish Research Council and ED in part by Meltzer
Stiftelsen, for which we are grateful. CC was supported by an NSF grant OCE-0085089.
The work described in this publication was supported by the European Community's
Sixth Framework Programme through the grant to the budget of the Integrated
Infrastructure Initiative HYDRALAB III, Contract no. 022441 (RII3)
High Pressure Thermoelasticity of Body-centered Cubic Tantalum
We have investigated the thermoelasticity of body-centered cubic (bcc)
tantalum from first principles by using the linearized augmented plane wave
(LAPW) and mixed--basis pseudopotential methods for pressures up to 400 GPa and
temperatures up to 10000 K. Electronic excitation contributions to the free
energy were included from the band structures, and phonon contributions were
included using the particle-in-a-cell (PIC) model. The computed elastic
constants agree well with available ultrasonic and diamond anvil cell data at
low pressures, and shock data at high pressures. The shear modulus and
the anisotropy change behavior with increasing pressure around 150 GPa because
of an electronic topological transition. We find that the main contribution of
temperature to the elastic constants is from the thermal expansivity. The PIC
model in conjunction with fast self-consistent techniques is shown to be a
tractable approach to studying thermoelasticity.Comment: To be appear in Physical Review
In-medium relativistic kinetic theory and nucleon-meson systems
Within the model of coupled nucleon-meson systems, a
generalized relativistic Lenard--Balescu--equation is presented resulting from
a relativistic random phase approximation (RRPA). This provides a systematic
derivation of relativistic transport equations in the frame of nonequilibrium
Green's function technique including medium effects as well as flucuation
effects. It contains all possible processes due to one meson exchange and
special attention is kept to the off--shell character of the particles. As a
new feature of many particle effects, processes are possible which can be
interpreted as particle creation and annihilation due to in-medium one meson
exchange. In-medium cross sections are obtained from the generalized derivation
of collision integrals, which possess complete crossing symmetries.Comment: See nucl-th/9310032 for revised version which the authors
incompetently resubmitted rather than correctly replacing thi
The GEM Project: an International Collaboration to Survey Galactic Radiation Emission
The GEM (Galactic Emission Mapping) project is an international collaboration
established with the aim of surveying the full sky at long wavelengths with a
multi-frequency radio telescope. A total of 745 hours of observation at 408 MHz
were completed from an Equatorial site in Colombia. The observations cover the
celestial band , and . Preliminary results of this partial survey will be
discussed. A review of the instrumental setup and a
resolution sky map at 408 MHz is presented.Comment: 6 pages, Plain Latex + 1 (uuencoded) PostScript figure Fig. 1 and
Fig. 2 not included, available from [email protected]
Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector
A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results
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