219 research outputs found
On the methodological unification in electroencephalography
BACKGROUND: This paper presents results of a pursuit of a repeatable and objective methodology of analysis of the electroencephalographic (EEG) time series. METHODS: Adaptive time-frequency approximations of EEG are discussed in the light of the available experimental and theoretical evidence, and applicability in various experimental and clinical setups. RESULTS: Four lemmas and three conjectures support the following conclusion. CONCLUSION: Adaptive time-frequency approximations of signals unify most of the univariate computational approaches to EEG analysis, and offer compatibility with its traditional (visual) analysis, used in clinical applications
The Groenewold - Moyal Plane and its Quantum Physics
Quantum theories constructed on the noncommutative spacetime called the
Groenewold-Moyal(GM) plane exhibit many interesting properties such as
causality violation, Lorentz and CPT non-invariance and twisted statistics.
Such violations lead to many striking features that may be tested
experimentally. Thus these theories predict Pauli-forbidden transitions due to
twisted statistics, anisotropies and acausal effects in the cosmic microwave
background radiation in correlations of observables and Lorentz and CPT
violations in scattering amplitudes. Such features of quantum physics on the GM
plane are surveyed in this review.Comment: 8 pages, Based on the talk given by APB at the XXV Max Born Symposium
on Planck Scale Physics, Wroclaw, 29 June-3 July 200
Information Infrastructure for Cooperative Research in Neuroscience
The paper describes a framework for efficient sharing of knowledge between research groups, which have been working for several years without flaws. The obstacles in cooperation are connected primarily with the lack of platforms for effective exchange of experimental data, models, and algorithms. The solution to these problems is proposed by construction of the platform (EEG.pl) with the semantic aware search scheme between portals. The above approach implanted in the international cooperative projects like NEUROMATH may bring the significant progress in designing efficient methods for neuroscience research
Brain Computer Interfaces for inclusion
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Phenyl 2,3,4-tri-O-benzyl-1-thio-α-d-mannopyranoside monohydrate
In the title compound, C33H34O5S·H2O, the mannopyranoside ring adopts a chair conformation with the 2-α-thiophenyl group occupying an axial position. One of the pendant benzyl groups is disordered over two sets of sites in a 0.5:0.5 ratio. In the crystal, the water molecule makes two O—H⋯O hydrogen bonds to an adjacent sugar molecule with the O atoms of the primary alcohol and ether groups acting as acceptors. At the same time, the OH group of the sugar makes a hydrogen bond to a water molecule
Open Database of Epileptic EEG with MRI and Postoperational Assessment of Foci—a Real World Verification for the EEG Inverse Solutions
This paper introduces a freely accessible database http://eeg.pl/epi, containing 23 datasets from patients diagnosed with and operated on for drug-resistant epilepsy. This was collected as part of the clinical routine at the Warsaw Memorial Child Hospital. Each record contains (1) pre-surgical electroencephalography (EEG) recording (10–20 system) with inter-ictal discharges marked separately by an expert, (2) a full set of magnetic resonance imaging (MRI) scans for calculations of the realistic forward models, (3) structural placement of the epileptogenic zone, recognized by electrocorticography (ECoG) and post-surgical results, plotted on pre-surgical MRI scans in transverse, sagittal and coronal projections, (4) brief clinical description of each case. The main goal of this project is evaluation of possible improvements of localization of epileptic foci from the surface EEG recordings. These datasets offer a unique possibility for evaluating different EEG inverse solutions. We present preliminary results from a subset of these cases, including comparison of different schemes for the EEG inverse solution and preprocessing. We report also a finding which relates to the selective parametrization of single waveforms by multivariate matching pursuit, which is used in the preprocessing for the inverse solutions. It seems to offer a possibility of tracing the spatial evolution of seizures in time
Lorentz-covariant Hamiltonian analysis of BF gravity with the Immirzi parameter
We perform the Lorentz-covariant Hamiltonian analysis of two Lagrangian
action principles that describe general relativity as a constrained BF theory
and that include the Immirzi parameter. The relation between these two
Lagrangian actions has been already studied through a map among the fields
involved. The main difference between these is the way the Immirzi parameter is
included, since in one of them the Immirzi parameter is included explicitly in
the BF terms, whereas in the other (the CMPR action) it is in the constraint on
the B fields. In this work we continue the analysis of their relationship but
at the Hamiltonian level. Particularly, we are interested in seeing how the
above difference appears in the constraint structure of both action principles.
We find that they both possess the same number of first-class and second-class
constraints and satisfy a very similar (off-shell) Poisson-bracket algebra on
account of the type of canonical variables employed. The two algebras can be
transformed into each other by making a suitable change of variablesComment: LaTeX file, no figure
Minority cytotypes in European populations of the Gymnadenia conopsea complex (Orchidaceae) greatly increase intraspecific and intrapopulation diversity
Background and Aims Patterns of ploidy variation among and within populations can provide valuable insights into the evolutionary mechanisms shaping the dynamics of plant systems showing ploidy diversity. Whereas data on majority ploidies are, by definition, often sufficiently extensive, much less is known about the incidence and evolutionary role of minority cytotypes. Methods Ploidy and proportions of endoreplicated genome were determined using DAPI (4',6-diamidino-2-phenylindole) flow cytometry in 6150 Gymnadenia plants (fragrant orchids) collected from 141 populations in 17 European countries. All widely recognized European species, and several taxa of less certain taxonomic status were sampled within Gymnadenia conopsea sensu lato. Key Results Most Gymnadenia populations were taxonomically and/or ploidy heterogeneous. Two majority (2x and 4x) and three minority (3x, 5x and 6x) cytotypes were identified. Evolution largely proceeded at the diploid level, whereas tetraploids were much more geographically and taxonomically restricted. Although minority ploidies constituted <2 % of the individuals sampled, they were found in 35 % of populations across the entire area investigated. The amount of nuclear DNA, together with the level of progressively partial endoreplication, separated all Gymnadenia species currently widely recognized in Europe. Conclusions Despite their low frequency, minority cytotypes substantially increase intraspecific and intrapopulation ploidy diversity estimates for fragrant orchids. The cytogenetic structure of Gymnadenia populations is remarkably dynamic and shaped by multiple evolutionary mechanisms, including both the ongoing production of unreduced gametes and heteroploid hybridization. Overall, it is likely that the level of ploidy heterogeneity experienced by most plant species/populations is currently underestimated; intensive sampling is necessary to obtain a holistic pictur
Barbero-Immirzi parameter, manifold invariants and Euclidean path integrals
The Barbero-Immirzi parameter appears in the \emph{real} connection
formulation of gravity in terms of the Ashtekar variables, and gives rise to a
one-parameter quantization ambiguity in Loop Quantum Gravity. In this paper we
investigate the conditions under which will have physical effects in
Euclidean Quantum Gravity. This is done by constructing a well-defined
Euclidean path integral for the Holst action with non-zero cosmological
constant on a manifold with boundary. We find that two general conditions must
be satisfied by the spacetime manifold in order for the Holst action and its
surface integral to be non-zero: (i) the metric has to be non-diagonalizable;
(ii) the Pontryagin number of the manifold has to be non-zero. The latter is a
strong topological condition, and rules out many of the known solutions to the
Einstein field equations. This result leads us to evaluate the on-shell
first-order Holst action and corresponding Euclidean partition function on the
Taub-NUT-ADS solution. We find that shows up as a finite rotation of
the on-shell partition function which corresponds to shifts in the energy and
entropy of the NUT charge. In an appendix we also evaluate the Holst action on
the Taub-NUT and Taub-bolt solutions in flat spacetime and find that in that
case as well shows up in the energy and entropy of the NUT and bolt
charges. We also present an example whereby the Euler characteristic of the
manifold has a non-trivial effect on black-hole mergers.Comment: 18 pages; v2: references added; to appear in Classical and Quantum
Gravity; v3: typos corrected; minor revisions to match published versio
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