89,863 research outputs found
Why Neural Correlates Of Consciousness Are Fine, \ud But Not Enough\ud
\ud
The existence of neural correlates of consciousness (NCC) is not enough for philosophical purposes. On the other hand, there's more to NCC than meets the sceptic's eye.\ud
(I) NCC are useful for a better understanding of conscious experience, for instance: (1) NCC are helpful to explain phenomenological features of consciousness – e.g., dreaming. (2) NCC can account for phenomenological opaque facts – e.g., the temporal structure of consciousness. (3) NCC reveal properties and functions of consciousness which cannot be elucidated either by introspective phenomenology or by psychological experiments alone – e.g., vision.\ud
(II) There are crucial problems and shortcomings of NCC: (1) Correlation implies neither causation nor identity. (2) There are limitations of empirical access due to the problem of other minds and the problem of self-deception, and (3) due to the restrictions provided by inter- and intraindividual variations. (4) NCC cannot be catched by neuroscience alone because of the externalistic content of representations. Therefore, NCC are not sufficient for a naturalistic theory of mind, (5) nor are they necessary because of the possibility of multiple realization.\ud
(III) Nevertheless, NCC are relevant and important for the mind-body problem: (1) NCC reveal features that are necessary at least for behavioral manifestations of human consciousness. (2) But NCC are compatible with very different proposals for a solution of the mind-body problem. This seems to be both advantageous and detrimental. (3) NCC restrict nomological identity accounts. (4) The investigation of NCC can refute empirical arguments for interactionism as a case study of John Eccles' dualistic proposals will show. (5) The discoveries of NCC cannot establish a naturalistic theory of mind alone, for which, e.g., a principle of supervenience and a further condition – and therefore philosophical arguments – are required.\u
Effects of thermal- and spin- fluctuations on the band structure of purple bronze LiMoO
The band structures of ordered and thermally disordered
LiMoO are calculated by use of ab-initio DFT-LMTO method. The
unusual, very 1-dimensional band dispersion obtained in previous band
calculations is confirmed for the ordered structure, and the overall band
structure agrees reasonably with existing photoemission data. Dispersion and
bandstructure perpendicular to the main dispersive direction is obtained. A
temperature dependent band broadening is calculated from configurations with
thermal disorder of the atomic positions within the unit cell. This leads a
band broadening of the two bands at the Fermi energy which can become
comparable to their energy separation. The bands are particularly sensitive to
in-plane movements of Mo sites far from the Li-sites, where the
density-of-states is highest. The latter fact makes the effect of Li vacancies
on the two bands relatively small. Spin-polarized band results for the ordered
structure show a surprisingly large exchange enhancement on the high DOS Mo
sites. Consequences for spin fluctuations associated with a cell doubling along
the conducting direction are discussed
Angular Structure of Jet Quenching Within a Hybrid Strong/Weak Coupling Model
Within the context of a hybrid strong/weak coupling model of jet quenching,
we study the modification of the angular distribution of the energy within jets
in heavy ion collisions, as partons within jet showers lose energy and get
kicked as they traverse the strongly coupled plasma produced in the collision.
To describe the dynamics transverse to the jet axis, we add the effects of
transverse momentum broadening into our hybrid construction, introducing a
parameter that governs its magnitude. We show that,
because of the quenching of the energy of partons within a jet, even when
the jets that survive with some specified energy in the final state
are narrower than jets with that energy in proton-proton collisions. For this
reason, many standard observables are rather insensitive to . We propose a
new differential jet shape ratio observable in which the effects of transverse
momentum broadening are apparent. We also analyze the response of the medium to
the passage of the jet through it, noting that the momentum lost by the jet
appears as the momentum of a wake in the medium. After freezeout this wake
becomes soft particles with a broad angular distribution but with net momentum
in the jet direction. We show that the particles coming from the response of
the medium to the momentum and energy deposited in it leads to a correlation
between the momentum of soft particles well separated from the jet in angle
with the direction of the jet momentum, and find qualitative but not
quantitative agreement with experimental data on observables designed to
extract such a correlation. By confronting the results that we obtain upon
introducing transverse momentum broadening and the response of the medium to
the jet with available jet data, we highlight the importance of these processes
for understanding the internal, soft, angular structure of high energy jets.Comment: 62 pages, 14 figure
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