232 research outputs found
EEG filtering based on blind source separation (BSS) for early detection of Alzheimer's disease
Objective: Development of an EEG preprocessing technique for improvement of detection of Alzheimerâs disease (AD). The technique is based on filtering of EEG data using blind source separation (BSS) and projection of components which are possibly sensitive to cortical neuronal impairment found in early stages of AD. Method: Artifact-free 20 s intervals of raw resting EEG recordings from 22 patients with Mild Cognitive Impairment (MCI) who later proceeded to AD and 38 age-matched normal controls were decomposed into spatio-temporally decorrelated components using BSS algorithm âAMUSEâ. Filtered EEG was obtained by back projection of components with the highest linear predictability. Relative power of filtered data in delta, theta, alpha1, alpha2, beta1, and beta 2 bands were processed with Linear Discriminant Analysis (LDA). Results: Preprocessing improved the percentage of correctly classified patients and controls computed with jack-knifing cross-validation from 59 to 73% and from 76 to 84%, correspondingly. Conclusions: The proposed approach can significantly improve the sensitivity and specificity of EEG based diagnosis. Significance: Filtering based on BSS can improve the performance of the existing EEG approaches to early diagnosis of Alzheimerâs disease. It may also have potential for improvement of EEG classification in other clinical areas or fundamental research. The developed method is quite general and flexible, allowing for various extensions and improvements. q 2004 Published by Elsevier Ireland Ltd. on behalf of International Federation of Clinical Neurophysiology
Fundamentals of Traffic Flow
From single vehicle data a number of new empirical results concerning the
density-dependence of the velocity distribution and its moments as well as the
characteristics of their temporal fluctuations have been determined. These are
utilized for the specification of some fundamental relations of traffic flow
and compared with existing traffic theories.Comment: For related work see
http://www.theo2.physik.uni-stuttgart.de/helbing.htm
Two-dimensional cellular automaton model of traffic flow with open boundaries
A two-dimensional cellular automaton model of traffic flow with open
boundaries are investigated by computer simulations. The outflow of cars from
the system and the average velocity are investigated. The time sequences of the
outflow and average velocity have flicker noises in a jamming phase. The low
density behavior are discussed with simple jam-free approximation.Comment: 14 pages, Phys. Rev. E in press, PostScript figures available at
ftp://hirose.ai.is.saga-u.ac.jp/pub/documents/papers/1996/2DTR/
OpenBoundaries/Figs.tar.g
Dynamical Phase Transition in One Dimensional Traffic Flow Model with Blockage
Effects of a bottleneck in a linear trafficway is investigated using a simple
cellular automaton model. Introducing a blockage site which transmit cars at
some transmission probability into the rule-184 cellular automaton, we observe
three different phases with increasing car concentration: Besides the free
phase and the jam phase, which exist already in the pure rule-184 model, the
mixed phase of these two appears at intermediate concentration with
well-defined phase boundaries. This mixed phase, where cars pile up behind the
blockage to form a jam region, is characterized by a constant flow. In the
thermodynamic limit, we obtain the exact expressions for several characteristic
quantities in terms of the car density and the transmission rate. These
quantities depend strongly on the system size at the phase boundaries; We
analyse these finite size effects based on the finite-size scaling.Comment: 14 pages, LaTeX 13 postscript figures available upon
request,OUCMT-94-
Phase II Trial of Preoperative Chemotherapy with Docetaxel, Cisplatin and S-1 for T4 Locally Advanced Gastric Cancer
The standard treatment for T4 locally advanced gastric cancer is gastrectomy with D2 lymph node dissection followed by adjuvant chemotherapy with S-1 for 12 months; however, prognostic outcome in Stage IIIb has been insufficient. It is expected that survival is improved by preoperative treatment with a triplet regimen of docetaxel, cisplatin and S-1 (divided DCS therapy). A multicenter Phase II study has been conducted to evaluate the safety and efficacy of two courses of preoperative chemotherapy followed by gastrectomy. Fifty-five patients are required for this study. The primary endpoint of the study is pathological response rate of primary lesions. Secondary endpoints are overall survival, disease-free survival, R0 resection rate and adverse events
Heuristic Segmentation of a Nonstationary Time Series
Many phenomena, both natural and human-influenced, give rise to signals whose
statistical properties change under time translation, i.e., are nonstationary.
For some practical purposes, a nonstationary time series can be seen as a
concatenation of stationary segments. Using a segmentation algorithm, it has
been reported that for heart beat data and Internet traffic fluctuations--the
distribution of durations of these stationary segments decays with a power law
tail. A potential technical difficulty that has not been thoroughly
investigated is that a nonstationary time series with a (scale-free) power law
distribution of stationary segments is harder to segment than other
nonstationary time series because of the wider range of possible segment sizes.
Here, we investigate the validity of a heuristic segmentation algorithm
recently proposed by Bernaola-Galvan et al. by systematically analyzing
surrogate time series with different statistical properties. We find that if a
given nonstationary time series has stationary periods whose size is
distributed as a power law, the algorithm can split the time series into a set
of stationary segments with the correct statistical properties. We also find
that the estimated power law exponent of the distribution of stationary-segment
sizes is affected by (i) the minimum segment size, and (ii) the ratio of the
standard deviation of the mean values of the segments, and the standard
deviation of the fluctuations within a segment. Furthermore, we determine that
the performance of the algorithm is generally not affected by uncorrelated
noise spikes or by weak long-range temporal correlations of the fluctuations
within segments.Comment: 23 pages, 14 figure
Plasma Electronics
Contains reports on twelve research projects.U. S. Atomic Energy Commission under Contract AT(30-1)-3285National Science Foundation (Grant GK-524
High-resolution microwave frequency dissemination on an 86-km urban optical link
We report the first demonstration of a long-distance ultra stable frequency
dissemination in the microwave range. A 9.15 GHz signal is transferred through
a 86-km urban optical link with a fractional frequency stability of 1.3x10-15
at 1 s integration time and below 10-18 at one day. The optical link phase
noise compensation is performed with a round-trip method. To achieve such a
result we implement light polarisation scrambling and dispersion compensation.
This link outperforms all the previous radiofrequency links and compares well
with recently demonstrated full optical links.Comment: 11 pages, 5 figure
Collective dynamics of two-mode stochastic oscillators
We study a system of two-mode stochastic oscillators coupled through their
collective output. As a function of a relevant parameter four qualitatively
distinct regimes of collective behavior are observed. In an extended region of
the parameter space the periodicity of the collective output is enhanced by the
considered coupling. This system can be used as a new model to describe
synchronization-like phenomena in systems of units with two or more oscillation
modes. The model can also explain how periodic dynamics can be generated by
coupling largely stochastic units. Similar systems could be responsible for the
emergence of rhythmic behavior in complex biological or sociological systems.Comment: 4 pages, RevTex, 5 figure
Measuring the frequency of a Sr optical lattice clock using a 120-km coherent optical transfer
We demonstrate a precision frequency measurement using a phase-stabilized
120-km optical fiber link over a physical distance of 50 km. The transition
frequency of the 87Sr optical lattice clock at the University of Tokyo is
measured to be 429228004229874.1(2.4) Hz referenced to international atomic
time (TAI). The measured frequency agrees with results obtained in Boulder and
Paris at a 6*10^-16 fractional level, which matches the current best
evaluations of Cs primary frequency standards. The results demonstrate the
excellent functions of the intercity optical fibre link, and the great
potential of optical lattice clocks for use in the redefinition of the second.Comment: 14 pages, 3 figure
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