31,425 research outputs found
Modelling the Product Development performance of Colombian Companies
Organised by: Cranfield UniversityThis paper presents the general model of the Product Development Process (PDP) in the Metal mechanics
Industry in Barranquilla-Colombia, since this sector contributes significantly to the productivity of this
industrial city. This case study counted on a five-company sample. The main goal was to model the current
conditions of the PDP according to the Concurrent Engineering philosophy. The companies were selected
according to their productive profile, in order to contrast differences regarding the structure of their
productive processes, conformation of multidisciplinary teams, integration of different areas, customers and
suppliers to the PDP; human resources, information, technology and marketing constraints.Mori Seiki – The Machine Tool Compan
BhaBAR: Big Halpha kinematical sample of BARred spiral galaxies - I. Fabry-Perot Observations of 21 galaxies
The Halpha gas kinematics of twenty-one representative barred spiral galaxies
belonging to the BHaBAR sample is presented. The galaxies were observed with
FaNTOmM, a Fabry-Perot integral-field spectrometer, on three different
telescopes. The 3D data cubes were processed through a robust pipeline with the
aim of providing the most homogeneous and accurate dataset possible useful for
further analysis. The data cubes were spatially binned to a constant
signal-to-noise ratio, typically around 7. Maps of the monochromatic Halpha
emission line and of the velocity field were generated and the kinematical
parameters were derived for the whole sample using tilted-ring models. The
photometrical and kinematical parameters (position angle of the major axis,
inclination, systemic velocity and kinematical centre) are in relative good
agreement, except maybe for the later-type spirals.Comment: 34 pages, 25 figures, accepted for publication in MNRAS. To obtain a
higher resolution version, go to
ftp://ftp.astro.umontreal.ca/outgoing/olivier/bhabar.pdf or to
http://www.astro.umontreal.ca/fantomm/bhabar
Inverse magnetic catalysis from the properties of the QCD coupling in a magnetic field
We compute the vacuum one-loop quark-gluon vertex correction at zero
temperature in the presence of a magnetic field. From the vertex function we
extract the effective quark-gluon coupling and show that it grows with
increasing magnetic field strength. The effect is due to a subtle competition
between the color charge associated to gluons and the color charge associated
to quarks, the former being larger than the latter. In contrast, at high
temperature the effective thermo-magnetic coupling results exclusively from the
contribution of the color charge associated to quarks. This produces a decrease
of the coupling with increasing field strength. We interpret the results in
terms of a geometrical effect whereby the magnetic field induces, on average, a
closer distance between the (electrically charged) quarks and antiquarks. At
high temperature, since the effective coupling is proportional only to the
color charge associated to quarks, such proximity with increasing field
strength makes the effective coupling decrease due to asymptotic freedom. In
turn, this leads to a decreasing quark condensate. In contrast, at zero
temperature both the effective strong coupling and the quark condensate
increase with increasing magnetic field. This is due to the color charge
associated to gluons dominating over that associated to quarks, with both
having the opposite sign. Thus, the gluons induce a kind of screening of the
quark color charge, in spite of the quark-antiquark proximity. The implications
of these results for the inverse magnetic catalysis phenomenon are discussed.Comment: Expanded discussion, references added. Version to appear in Phys.
Lett.
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