2,840 research outputs found
Cortical Mirror-System Activation During Real-Life Game Playing: An Intracranial Electroencephalography (EEG) Study
Analogous to the mirror neuron system repeatedly described in monkeys as a
possible substrate for imitation learning and/or action understanding, a
neuronal execution/observation matching system (OEMS) is assumed in humans, but
little is known to what extent this system is activated in non-experimental,
real-life conditions. In the present case study, we investigated brain activity
of this system during natural, non-experimental motor behavior as it occurred
during playing of the board game "Malefiz". We compared spectral modulations of
the high-gamma band related to ipsilateral reaching movement execution and
observation of the same kind of movement using electrocorticography (ECoG) in
one participant. Spatially coincident activity during both conditions execution
and observation was recorded at electrode contacts over the premotor/primary
motor cortex. The topography and amplitude of the high-gamma modulations
related to both, movement observation and execution were clearly spatially
correlated over several fronto-parietal brain areas. Thus, our findings
indicate that a network of cortical areas contributes to the human OEMS, beyond
primary/premotor cortex including Brocas area and the temporo-parieto-occipital
junction area, in real-life conditions.Comment: 4 pages, 2 figure, CCN 2018 conference pape
A Note on Wandzura-Wilczek Relations
Wandzura-Wilczek (WW) relations between matrix-elements of bilocal light-ray
operators have recently regained interest in connection with off-forward
scattering processes. Originally derived for matrix elements over leading-twist
operators, their generalization to off-forward and exclusive processes gets
complicated by the presence of higher-twist operators that are total
derivatives of leading-twist ones and do not contribute to forward-scattering.
We demonstrate that, for exclusive matrix-elements, the inclusion of these
operators into WW-relations is essential for fulfilling constraints imposed by
the conformal symmetry of massless QCD.Comment: 4 pages RevTe
Our place is special: the response of a major fossil-fuel company to emissions trading developments in New Zealand
Purpose: To examine and interpret the activity, arguments, and policy proposals put forward over a four-year period by a major state-owned fossil-fuel company, on climate-change policy and emissions trading in New Zealand. Design/methodology/approach: The signing of the Kyoto protocol by the New Zealand Government in 1997, followed by the introduction of Climate Change Response legislation in 2002, and the proposed introduction, and subsequent implementation, of a New Zealand emissions trading scheme between 2007-2011, provide the empirical context for our research. In order to investigate the position on GHG management of a key member of the fossil-fuel industry, submissions on each of the four stages of pre-consultation and review process on the emissions trading scheme were analysed, with a focus on key arguments, policy proposals, and degree of involvement in policy formulation. The company responses were evaluated from a legitimacy theory perspective. Findings: A notable position on emissions control, in which it was argued that New Zealand should be allowed to increase gross emissions over time, whilst relying on carbon sinks, primarily forestry, in order to meet net emissions targets, was revealed. The rationale was that since most New Zealand production processes are less emissions intensive than those elsewhere, New Zealand should enjoy a privileged position in the production of certain commodities relative to other countries. Economic growth, emissions leakage and energy efficiency arguments were invoked to support the position that net emissions reductions should only be made if required by international treaty obligations, and then only in line with actions of key trading partners. It was argued that if an emissions trading scheme were to proceed it should provide maximum support for emitters, free allocations, subsidised allocations, delayed entry of sectors into the scheme and an extended phase-out period for free allocations. The company was found to have played a major role in the submissions process
-Meson wave functions from nonlocal light-cone operators with definite twist
We introduce chiral-even and chiral-odd meson wave functions as
vacuum-to-meson matrix elements of bilocal quark operators with well-defined
(geometric) twist. Thereby, we achieve a Lorentz invariant classification of
these distributions which differ from the conventional ones by explicitly
taking into account the trace terms. The relations between conventional and new
wave functions are given.Comment: 8 pages, REVTEX; corrected sign error
An Analytic Formula and an Upper Bound for epsilon'/epsilon in the Standard Model
Using the idea of the penguin box expansion we find an analytic expression
for epsilon'/epsilon in the Standard Model as a function of m_t, m_s(m_c) and
two non-perturbative parameters B_6 and B_8. This formula includes
next-to-leading QCD/QED short distance effects calculated recently by means of
the operator product expansion and renormalization group techniques. We also
derive an analytic expression for the upper bound on epsilon'/epsilon as a
function of |V_cb|, |V_ub/V_cb|, B_K and other relevant parameters. Numerical
examples of the bound are given.Comment: 10 pages with 1 figure appended in PostScript format; MPI preprint
MPI-Ph/93-60 and TU preprint TUM-T31-47/9
Primary and secondary scintillation measurements in a Xenon Gas Proportional Scintillation Counter
16 páginas, 10 figuras, 1 tabla.-- El PDF es la versión post-print.-- et al.NEXT is a new experiment to search for neutrinoless double beta decay using a 100 kg radio-pure high-pressure gaseous xenon TPC. The detector requires excellent energy resolution, which can be achieved in a Xe TPC with electroluminescence readout. Hamamatsu R8520-06SEL photomultipliers are good candidates for the scintillation readout. The performance of this photomultiplier, used as VUV photosensor in a gas proportional scintillation counter, was investigated. Initial results for the detection of primary and secondary scintillation produced as a result of the interaction of 5.9 keV X-rays in gaseous xenon, at room temperature and at pressures up to 3 bar, are presented. An energy resolution of 8.0% was obtained for secondary scintillation produced by 5.9 keV X-rays. No significant variation of the primary scintillation was observed for different pressures (1, 2 and 3 bar) and for electric fields up to 0.8 V cm-1 torr-1 in the drift region, demonstrating negligible recombination luminescence. A primary scintillation yield of 81 ± 7 photons was obtained for 5.9 keV X-rays, corresponding to a mean energy of 72 ± 6 eV to produce a primary scintillation photon in xenon.This work was supported by FCT (Portugal) and FEDER through project PTDC/FIS/103860/2008. E.D.C. Freitas acknowledges grant SFRH/BD/46711/2008 from FCT. C.M.B. Monteiro acknowledges grant SFRH/BD/25569/2005 from FCT. M. Ball, J.J. Gómez-Cadenas and N. Yahlali acknowledge the Spanish MICINN for the Consolider-Ingenio grants CSD2008-00037 and CSD2007-00042 and the research grants FPA2009-13697-C04-04 and FPA2009-13697-C04-B23/12. D.R. Nygren acknowledges support by the Director, Office of Science, Office of High Energy Physics, of the U.S. Department of Energy under contract DE-AC02-05CH11231.Peer reviewe
Deposition Mechanism and Properties of Thin Polydopamine Films for High Added Value Applications in Surface Science at the Nanoscale
Polydopamine films have been introduced by Messersmith et al. as a possible “versatile” surface functionalization method allowing to coat the surface of almost all known materials even superhydrophobic surfaces. These new kinds of coatings also confer a plethora of functionalities to the coated materials owing to the complex chemistry of the catechol quinone moieties present on the surface of polydopamine. These coatings may hence become an interesting alternative to established surface coatings like self-assembled monolayers and polyelectrolyte multilayered films. In this review, we describe the knowledge acquired in the last 3 years about the deposition mechanisms of polydopamine films, their properties, and various applications in surface science at the nanoscale.Fonds Europeen de Developpement Economique et Regional (Chaptochem Project 2009-02-039-35
Decomposition of nonlocal light-cone operators into harmonic operators of definite twist
Bilocal light-ray operators which are Lorentz scalars, vectors or
antisymmetric tensors, and which appear in various hard scattering QCD
processes, are decomposed into operators of definite twist. These operators are
harmonic tensor functions and their Taylor expansion consists of (traceless)
local light-cone operators with span irreducible representations of the Lorentz
group with definite spin j and common geometric twist (= dimension - spin).
Some applications concerning the nonforward matrix elements of these operators
and the generalization fo conformal light-cone operators of definite twist is
considered. The group theoretical background of the method has been made clear.Comment: 38 pages, AMSTEX Improvement of expressions for twist-3 and twist-4
tensor operators. to appear in Nucl. Phys.
Parton distribution functions from nonlocal light-cone operators with definite twist
We introduce the chiral-even and chiral-odd quark distributions as forward
matrix elements of related bilocal quark operators with well-defined
(geometric) twist. Thereby, we achieve a Lorentz invariant classification of
these distributions which differ from the conventional ones by explicitly
taking into account the necessary trace terms. The relations between both kinds
of distribution functions are given and the mismatch between their different
definition of twist is discussed. Wandzura-Wilczek--like relations between the
conventional distributions (based on dynamical twist) are derived by means of
geometric twist distribution functions.Comment: 17 pages, REVTEX, Extended version, The Introduction has been
rewritten, Setion V "Wandzura-Wilczek--like relations" and App. B are added;
Sign errors are correcte
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