30,582 research outputs found
The structural contradictions and constraints on corporate social responsibility: Challenges for corporate social irresponsibility
Purpose - This chapter engages critically with the ideas of corporate social responsibility (CSR) and irresponsibility (CSI) in order to examine their utility for the purposes of realizing more socially just and environmentally sustainable social and economic practices. Methodology/approach - The chapter develops Marx's understanding of the twin pressures of class struggle and inter-capitalist competition in setting the limits of agency for corporate actors. It is thus theoretical and discursive in nature. Findings - The findings of the chapter suggest that the scope for corporate agency in relation to responsibility/irresponsibility is severely limited by inter-capitalist competition and capitalist social relations. It therefore argues that those interested in social justice and environmental sustainability should focus on these structural pressures rather than theorizing corporate agency. Social implications - The research suggests that the focus of academic and government attention should be on resolving the contradictions and exploitative social relations inherent in capitalism. Without this emphasis activism, corporate agency and government action will not eradicate the types of problem that advocates of CSR/CSI are concerned about. Originality/value of paper - The value of the paper is that it contests and engages critically with the utility of the notion of CSR and the emergent concept of CSI. It asks proponents of these concepts to think seriously about the structural pressures and constraints within which business and policy makers act. Copyrightr © 2012 by Emerald Group Publishing Limited
Zeeman-Tomography of the Solar Photosphere -- 3-Dimensional Surface Structures Retrieved from Hinode Observations
AIMS :The thermodynamic and magnetic field structure of the solar photosphere
is analyzed by means of a novel 3-dimensional spectropolarimetric inversion and
reconstruction technique. METHODS : On the basis of high-resolution,
mixed-polarity magnetoconvection simulations, we used an artificial neural
network (ANN) model to approximate the nonlinear inverse mapping between
synthesized Stokes spectra and the underlying stratification of atmospheric
parameters like temperature, line-of-sight (LOS) velocity and LOS magnetic
field. This approach not only allows us to incorporate more reliable physics
into the inversion process, it also enables the inversion on an absolute
geometrical height scale, which allows the subsequent combination of individual
line-of-sight stratifications to obtain a complete 3-dimensional reconstruction
(tomography) of the observed area. RESULTS : The magnetoconvection simulation
data, as well as the ANN inversion, have been properly processed to be
applicable to spectropolarimetric observations from the Hinode satellite. For
the first time, we show 3-dimensional tomographic reconstructions (temperature,
LOS velocity, and LOS magnetic field) of a quiet sun region observed by Hinode.
The reconstructed area covers a field of approximately 12000 by 12000 km and a
height range of 510 km in the photosphere. An enormous variety of small and
large scale structures can be identified in the 3-D reconstructions. The
low-flux region (B_{mag} = 20G) we analyzed exhibits a number of "tube-like"
magnetic structures with field strengths of several hundred Gauss. Most of
these structures rapidly loose their strength with height and only a few larger
structures can retain a higher field strength to the upper layers of the
photosphere.Comment: accepted for A&A Letter
Lorentz-Violating Vector Fields Slow the Universe Down
We consider the gravitational effects of a single, fixed-norm,
Lorentz-violating timelike vector field. In a cosmological background, such a
vector field acts to rescale the effective value of Newton's constant. The
energy density of this vector field precisely tracks the energy density of the
rest of the universe, but with the opposite sign, so that the universe
experiences a slower rate of expansion for a given matter content. This vector
field similarly rescales Newton's constant in the Newtonian limit, although by
a different factor. We put constraints on the parameters of the theory using
the predictions of primordial nucleosynthesis, demonstrating that the norm of
the vector field should be less than the Planck scale by an order of magnitude
or more.Comment: 15 pages, Revtex4, updated version. Added References. Minor Typos
corrected. Older version published in PR
Optical realization of relativistic non-Hermitian quantum mechanics
Light propagation in distributed feedback optical structures with gain/loss
regions is shown to provide an accessible laboratory tool to visualize in
optics the spectral properties of the one-dimensional Dirac equation with
non-Hermitian interactions. Spectral singularities and PT symmetry breaking of
the Dirac Hamiltonian are shown to correspond to simple observable physical
quantities and related to well-known physical phenomena like resonance
narrowing and laser oscillation.Comment: 4 page
Vector field theories in cosmology
Recently proposed theories based on the cosmic presence of a vectorial field
are compared and contrasted. In particular the so called Einstein aether theory
is discussed in parallel with a recent proposal of a strained space-time theory
(Cosmic Defect theory). We show that the latter fits reasonably well the cosmic
observed data with only one, or at most two, adjustable parameters, whilst
other vector theories use much more. The Newtonian limits are also compared.
Finally we show that the CD theory may be considered as a special case of the
aether theories, corresponding to a more compact and consistent paradigm.Comment: 19 pages, 1 figure, to appear on Phys. Rev.
Map-Based Navigation in a Graphical MOO
Traditional MUDs and MOOs lack support for global wareness and simple navigation. These problems can be addressed by the introduction of a map-based navigation tool. In this paper we report on the design and evaluation of such a tool for MOOsburg, a graphical 2D MOO based on the town of Blacksburg, Virginia. The tool supports exploration and place-based tasks in the MOO. It also allows navigation of a large-scale map and encourages users to develop survey knowledge of the town. An evaluation revealed some initial usability problems with our prototype and suggested new design ideas that may better support users. Using these results, the lessons learned about map-based navigation are presented
A fast method for Stokes profile synthesis -- Radiative transfer modeling for ZDI and Stokes profile inversion
The major challenges for a fully polarized radiative transfer driven approach
to Zeeman-Doppler imaging are still the enormous computational requirements. In
every cycle of the iterative interplay between the forward process (spectral
synthesis) and the inverse process (derivative based optimization) the Stokes
profile synthesis requires several thousand evaluations of the polarized
radiative transfer equation for a given stellar surface model. To cope with
these computational demands and to allow for the incorporation of a full Stokes
profile synthesis into Doppler- and Zeeman-Doppler imaging applications as well
as into large scale solar Stokes profile inversions, we present a novel fast
and accurate synthesis method for calculating local Stokes profiles. Our
approach is based on artificial neural network models, which we use to
approximate the complex non-linear mapping between the most important
atmospheric parameters and the corresponding Stokes profiles. A number of
specialized artificial neural networks, are used to model the functional
relation between the model atmosphere, magnetic field strength, field
inclination, and field azimuth, on one hand and the individual components
(I,Q,U,V) of the Stokes profiles, on the other hand. We performed an extensive
statistical evaluation and show that our new approach yields accurate local as
well as disk-integrated Stokes profiles over a wide range of atmospheric
conditions. The mean rms errors for the Stokes I and V profiles are well below
0.2% compared to the exact numerical solution. Errors for Stokes Q and U are in
the range of 1%. Our approach does not only offer an accurate approximation to
the LTE polarized radiative transfer it, moreover, accelerates the synthesis by
a factor of more than 1000.Comment: A&A, in pres
Extremal black holes, gravitational entropy and nonstationary metric fields
We show that extremal black holes have zero entropy by pointing out a simple
fact: they are time-independent throughout the spacetime and correspond to a
single classical microstate. We show that non-extremal black holes, including
the Schwarzschild black hole, contain a region hidden behind the event horizon
where all their Killing vectors are spacelike. This region is nonstationary and
the time labels a continuous set of classical microstates, the phase space
, where is a three-metric induced on a
spacelike hypersurface and is its momentum conjugate. We
determine explicitly the phase space in the interior region of the
Schwarzschild black hole. We identify its entropy as a measure of an outside
observer's ignorance of the classical microstates in the interior since the
parameter which labels the states lies anywhere between 0 and 2M. We
provide numerical evidence from recent simulations of gravitational collapse in
isotropic coordinates that the entropy of the Schwarzschild black hole stems
from the region inside and near the event horizon where the metric fields are
nonstationary; the rest of the spacetime, which is static, makes no
contribution. Extremal black holes have an event horizon but in contrast to
non-extremal black holes, their extended spacetimes do not possess a bifurcate
Killing horizon. This is consistent with the fact that extremal black holes are
time-independent and therefore have no distinct time-reverse.Comment: 12 pages, 2 figures. To appear in Class. and Quant. Gravity. Based on
an essay selected for honorable mention in the 2010 gravity research
foundation essay competitio
Rippled Cosmological Dark Matter from Damped Oscillating Newton Constant
Let the reciprocal Newton 'constant' be an apparently non-dynamical
Brans-Dicke scalar field damped oscillating towards its General Relativistic
VEV. We show, without introducing additional matter fields or dust, that the
corresponding cosmological evolution averagely resembles, in the Jordan frame,
the familiar dark radiation -> dark matter -> dark energy domination sequence.
The fingerprints of our theory are fine ripples, hopefully testable, in the FRW
scale factor; they die away at the General Relativity limit. The possibility
that the Brans-Dicke scalar also serves as the inflaton is favorably examined.Comment: RevTex4, 12 pages, 5 figures; Minor revision, References adde
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