10,557 research outputs found
Parting layers, ash trays and Ramesside glassmaking: an experimental study
A series of glassmaking and glass colouring
replication experiments was undertaken in order to
test some of the current hypotheses concerning Late
Bronze Age glass production at Qantir-Piramesses.
These were based on the model of glassmaking
developed in this volume, and aimed in particular to
test the behaviour of the parting layer and the local
ceramic under the proposed chemical and thermal
conditions. Modern ash trays made out of Egyptian
Nile silt clay were used as proxies for LBA reaction
vessels and crucibles, and both raw glass and
coloured glass ingots were produced in them. This
experimental study, based on detailed observation
and technical studies of archaeological samples from
Qantir-Piramesses, not only provides material
readily comparable to the archaeological finds, but
brings to the forefront practical issues concerning the
nature of the parting layer, its application, the
melting procedures, the re-use of crucibles, and
indirect evidence of primary production, such as the
impact of sodium chloride, a major component of
plant ashes, on the ceramic. Although this string of
experiments does not fully replicate LBA
glassmaking technology, much information was
obtained and further areas of ambiguity identified
A record current account deficit: causes and implications
The U.S. current account deficit was at a record level in 1999 and is expected to increase further in 2000. How large can this deficit get? Will an eventual adjustment in the deficit place the U.S. economy at risk? This article examines three arguments often put forth to explain the increase in the deficit--a consumption boom, the U.S. as a safe haven for short-term foreign capital and technological change affecting the U.S. economy. The authors find the strongest evidence in support of technological change and suggest why, under these conditions, an economic adjustment to the deficit need not to have as adverse an impact as some observes fear.Deficit financing ; Economic conditions - United States
The binational Great Lakes economy
Great Lakes ; North American Free Trade Agreement ; Canada ; Manufactures
Coupling JOREK and STARWALL for Non-linear Resistive-wall Simulations
The implementation of a resistive-wall extension to the non-linear MHD-code
JOREK via a coupling to the vacuum-field code STARWALL is presented along with
first applications and benchmark results. Also, non-linear saturation in the
presence of a resistive wall is demonstrated. After completion of the ongoing
verification process, this code extension will allow to perform non-linear
simulations of MHD instabilities in the presence of three-dimensional resistive
walls with holes for limited and X-point plasmas.Comment: Contribution for "Theory Of Fusion Plasmas, Joint Varenna - Lausanne
International Workshop, Villa Monastero, Varenna, Italy (27.-31.8.2012)",
accepted for publication in Journal of Physics Conference Serie
Is inner core seismic anisotropy a marker for plastic flow of cubic iron?
International audienceThis paper investigates whether observations of seismic anisotropy are compatible with a cubic structure of the inner core Fe alloy.We assume that anisotropy is the result of plastic deformation within a large scale flow induced by preferred growth at the inner core equator. Based on elastic moduli from the literature, bcc- or fcc-Fe produce seismic anisotropy well below seismic observations (). A Monte-Carlo approach allows us to generalize this result to any form of elastic anisotropy in a cubic system. Within our model, inner core global anisotropy is not compatible with a cubic structure of Fe alloy.Hence, if the inner core material is indeed cubic, large scale coherent anisotropic structures, incompatible with plastic deformation induced by large scale flow, must be present
Measuring cellular traction forces on non-planar substrates
Animal cells use traction forces to sense the mechanics and geometry of their
environment. Measuring these traction forces requires a workflow combining cell
experiments, image processing and force reconstruction based on elasticity
theory. Such procedures have been established before mainly for planar
substrates, in which case one can use the Green's function formalism. Here we
introduce a worksflow to measure traction forces of cardiac myofibroblasts on
non-planar elastic substrates. Soft elastic substrates with a wave-like
topology were micromolded from polydimethylsiloxane (PDMS) and fluorescent
marker beads were distributed homogeneously in the substrate. Using feature
vector based tracking of these marker beads, we first constructed a hexahedral
mesh for the substrate. We then solved the direct elastic boundary volume
problem on this mesh using the finite element method (FEM). Using data
simulations, we show that the traction forces can be reconstructed from the
substrate deformations by solving the corresponding inverse problem with a
L1-norm for the residue and a L2-norm for 0th order Tikhonov regularization.
Applying this procedure to the experimental data, we find that cardiac
myofibroblast cells tend to align both their shapes and their forces with the
long axis of the deformable wavy substrate.Comment: 34 pages, 9 figure
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