152 research outputs found
Epistemic injustice: an epiphenomenon of advertising communication
Advertising as a simulacrum, an artifact of modern mythologized society has for a while been in the focus of philosophical research, but the phenomenon of epistemic injustice generated by advertising communication still requires reflection. The article reveals the role of advertising mechanisms in forming epistemic injustice in modern social landscape; the relationship between trust in advertising, its reliability and the development of epistemic virtue among the participants in the communication process is determined; the classical typology of epistemic injustice put forward by M. Fricker is further elaborated. The author comes to the conclusion that modern advertising generates a special type of epistemic injustice, affecting both the recipient of the message, who is always potentially deceived when in contact with advertising, and the informant, who suffers from identity prejudices and related testimonial injustice. The problem of the epistemological status of advertising becomes one of the epistemic virtue of the consumer, who must be able to correctly assess the context and take responsibility for the economic choice, since advertising as a communicative phenomenon a priori has the right to distort reality for the sake of survival of one of the elements of the business system and consumption in society as a whole. Current legislation which is designed to promote the rights of citizens to receive reliable information about products or services, does not guarantee the truth of advertising claims, as it is aimed at maintaining the dominant discourse, just like advertising. The way out of the situation of epistemic injustice seems to be switching from the experience of consuming advertising messages to the experience of consuming the product itself, cultivating acquired epistemic virtue and introducing a non-institutionalized form of social control that involves monitoring in order to detect false advertising and disseminating this information in the communicative space of the society of the post-knowledge era
Finite size effects and magnetic order in the spin-1/2 honeycomb lattice compound InCu{2/3}V{1/3}O{3}
High field electron spin resonance, nuclear magnetic resonance and
magnetization studies addressing the ground state of the quasi two-dimensional
spin-1/2 honeycomb lattice compound InCu{2/3}V{1/3}O{3} are reported.
Uncorrelated finite size structural domains occurring in the honeycomb planes
are expected to inhibit long range magnetic order. Surprisingly, ESR data
reveal the development of two collinear antiferromagnetic (AFM) sublattices
below ~ 20 K whereas NMR results show the presence of the staggered internal
field. Magnetization data evidence a spin reorientation transition at ~ 5.7 T.
Quantum Monte-Carlo calculations show that switching on the coupling between
the honeycomb spin planes in a finite size cluster yields a Neel-like AFM spin
structure with a substantial staggered magnetization at finite temperatures.
This may explain the occurrence of a robust AFM state in InCu{2/3}V{1/3}O{3}
despite an unfavorable effect of structural disorder.Comment: revised version, accepted as a Rapid Communication in Phys. Rev. B
(2010
Magnetic properties of vanadium-oxide nanotubes probed by static magnetization and {51}V NMR
Measurements of the static magnetic susceptibility and of the nuclear
magnetic resonance of multiwalled vanadium-oxide nanotubes are reported. In
this nanoscale magnet the structural low-dimensionality and mixed valency of
vanadium ions yield a complex temperature dependence of the static
magnetization and the nuclear relaxation rates. Analysis of the different
contributions to the magnetism allows to identify individual interlayer
magnetic sites as well as strongly antiferromagnetically coupled vanadium spins
(S = 1/2) in the double layers of the nanotube's wall. In particular, the data
give strong indications that in the structurally well-defined vanadium-spin
chains in the walls, owing to an inhomogeneous charge distribution,
antiferromagnetic dimers and trimers occur. Altogether, about 30% of the
vanadium ions are coupled in dimers, exhibiting a spin gap of the order of 700
K, the other ~ 30% comprise individual spins and trimers, whereas the remaining
\~ 40% are nonmagnetic.Comment: revised versio
High temperature ferromagnetism of Li-doped vanadium oxide nanotubes
The nature of a puzzling high temperature ferromagnetism of doped
mixed-valent vanadium oxide nanotubes reported earlier by Krusin-Elbaum et al.,
Nature 431 (2004) 672, has been addressed by static magnetization, muon spin
relaxation, nuclear magnetic and electron spin resonance spectroscopy
techniques. A precise control of the charge doping was achieved by
electrochemical Li intercalation. We find that it provides excess electrons,
thereby increasing the number of interacting magnetic vanadium sites, and, at a
certain doping level, yields a ferromagnetic-like response persisting up to
room temperature. Thus we confirm the surprising previous results on the
samples prepared by a completely different intercalation method. Moreover our
spectroscopic data provide first ample evidence for the bulk nature of the
effect. In particular, they enable a conclusion that the Li nucleates
superparamagnetic nanosize spin clusters around the intercalation site which
are responsible for the unusual high temperature ferromagnetism of vanadium
oxide nanotubes.Comment: with some amendments published in Europhysics Letters (EPL) 88 (2009)
57002; http://epljournal.edpsciences.or
Magnetic phase diagram and possible Kitaev-like behavior of honeycomb-lattice antimonate Na3Co2SbO6
Recent theoretical studies have suggested that Kitaev physics and such
effects as formation of a mysterious spin-liquid state can be expected not only
in RuCl3 and iridates, but also in conventional transition metal
compounds. Using DC and AC magnetometry, thermodynamic and Na nuclear
magnetic resonance measurements (NMR) we studied such a candidate material
Na3Co2SbO6 . A full phase diagram of Na3Co2SbO6 in a wide range of magnetic
fields and temperatures is presented. The results demonstrate transformation of
the magnetic structure realized at low-temperature and suppression of the AFM
order under the external field, the gradual development of the saturation
phase, as well as evidence of gapped spin-liquid-like behavior in certain parts
of the phase diagram
Magnetic properties of the low-dimensional spin-1/2 magnet \alpha-Cu_2As_2O_7
In this work we study the interplay between the crystal structure and
magnetism of the pyroarsenate \alpha-Cu_2As_2O_7 by means of magnetization,
heat capacity, electron spin resonance and nuclear magnetic resonance
measurements as well as density functional theory (DFT) calculations and
quantum Monte Carlo (QMC) simulations. The data reveal that the magnetic Cu-O
chains in the crystal structure represent a realization of a quasi-one
dimensional (1D) coupled alternating spin-1/2 Heisenberg chain model with
relevant pathways through non-magnetic AsO_4 tetrahedra. Owing to residual 3D
interactions antiferromagnetic long range ordering at T_N\simeq10K takes place.
Application of external magnetic field B along the magnetically easy axis
induces the transition to a spin-flop phase at B_{SF}~1.7T (2K). The
experimental data suggest that substantial quantum spin fluctuations take place
at low magnetic fields in the ordered state. DFT calculations confirm the
quasi-one-dimensional nature of the spin lattice, with the leading coupling J_1
within the structural dimers. QMC fits to the magnetic susceptibility evaluate
J_1=164K, the weaker intrachain coupling J'_1/J_1 = 0.55, and the effective
interchain coupling J_{ic1}/J_1 = 0.20.Comment: Accepted for publication in Physical Review
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