2,778 research outputs found
Frequency and Phase Synchronization in Neuromagnetic Cortical Responses to Flickering-Color Stimuli
In our earlier study dealing with the analysis of neuromagnetic responses
(magnetoencephalograms - MEG) to flickering-color stimuli for a group of
control human subjects (9 volunteers) and a patient with photosensitive
epilepsy (a 12-year old girl), it was shown that Flicker-Noise Spectroscopy
(FNS) was able to identify specific differences in the responses of each
organism. The high specificity of individual MEG responses manifested itself in
the values of FNS parameters for both chaotic and resonant components of the
original signal. The present study applies the FNS cross-correlation function
to the analysis of correlations between the MEG responses simultaneously
measured at spatially separated points of the human cortex processing the
red-blue flickering color stimulus. It is shown that the cross-correlations for
control (healthy) subjects are characterized by frequency and phase
synchronization at different points of the cortex, with the dynamics of
neuromagnetic responses being determined by the low-frequency processes that
correspond to normal physiological rhythms. But for the patient, the frequency
and phase synchronization breaks down, which is associated with the suppression
of cortical regulatory functions when the flickering-color stimulus is applied,
and higher frequencies start playing the dominating role. This suggests that
the disruption of correlations in the MEG responses is the indicator of
pathological changes leading to photosensitive epilepsy, which can be used for
developing a method of diagnosing the disease based on the analysis with the
FNS cross-correlation function.Comment: 21 pages, 14 figures; submitted to "Laser Physics", 2010, 2
Measurement of low turbulence levels with a thermoanemometer
The trend for decreasing the drag of aircraft is retention of laminar flow in the boundary layer over a large portion of the surface. The laminar boundary layer was studied in a low turbulence wind tunnel for low subsonic velocities. The method used and results of measurements of very low levels of turbulence are presented. Measurements were performed by a constant-resistance thermoanemometer
DELPHES 3, A modular framework for fast simulation of a generic collider experiment
The version 3.0 of the DELPHES fast-simulation is presented. The goal of
DELPHES is to allow the simulation of a multipurpose detector for
phenomenological studies. The simulation includes a track propagation system
embedded in a magnetic field, electromagnetic and hadron calorimeters, and a
muon identification system. Physics objects that can be used for data analysis
are then reconstructed from the simulated detector response. These include
tracks and calorimeter deposits and high level objects such as isolated
electrons, jets, taus, and missing energy. The new modular approach allows for
greater flexibility in the design of the simulation and reconstruction
sequence. New features such as the particle-flow reconstruction approach,
crucial in the first years of the LHC, and pile-up simulation and mitigation,
which is needed for the simulation of the LHC detectors in the near future,
have also been implemented. The DELPHES framework is not meant to be used for
advanced detector studies, for which more accurate tools are needed. Although
some aspects of DELPHES are hadron collider specific, it is flexible enough to
be adapted to the needs of electron-positron collider experiments.Comment: JHEP 1402 (2014
Proton-He elastic scattering at low energies
We present new accurate measurements of the differential cross section
and the proton analyzing power for proton-He
elastic scattering at various energies. A supersonic gas jet target has been
employed to obtain these low energy cross section measurements. The
distributions have been measured at = 0.99, 1.59,
2.24, 3.11, and 4.02 MeV. Full angular distributions of have been
measured at = 1.60, 2.25, 3.13, and 4.05 MeV. This set of
high-precision data is compared to four-body variational calculations employing
realistic nucleon-nucleon (NN) and three-nucleon (3N) interactions. For the
unpolarized cross section the agreement between the theoretical calculation and
data is good when a potential is used. The comparison between the
calculated and measured proton analyzing powers reveals discrepancies of
approximately 50% at the maximum of each distribution. This is analogous to the
existing `` Puzzle'' known for the past 20 years in nucleon-deuteron
elastic scattering.Comment: 22 pages, 9 figures, to be published in Physical Review C, corrected
reference 4
Topochemical differences in the amount of RNA in the motoneurons of the spinal chord in hypoxia and hypokinesia
Reactions to hypoxia and hypoknesia were compared by measuring charges in the amount of ribonucleic acid (RNA) in the cytoplasm of neurons of the intumescentia cervicalis and lumbalis. Animals were subjected to hypoxia, hypokinesia and both combined and a control group to neither. A total of two groups of motoneurons were compared, one innervating the respiratory musculature, the other the musculature of the lower extremities, so that hypoxic hypoxia would probably affect the first group primarily and hypokinesia the second. Results indicate that neither affect the amount of RNA in the neurons of the first group but a significant increase is noted in neurons of the second group. Other significant results are reported
Towards portable muography with small-area, gas-tight glass Resistive Plate Chambers
Imaging techniques that use atmospheric muons, collectively named under the
neologism "muography", have seen a tremendous growth in recent times, mainly
due to their diverse range of applications. The most well-known ones include
but are not limited to: volcanology, archaeology, civil engineering, nuclear
reactor monitoring, nuclear waste characterization, underground mapping, etc.
These methods are based on the attenuation or deviation of muons to image large
and/or dense objects where conventional techniques cannot work or their use
becomes challenging.
In this context, we have constructed a muography telescope based on "mini
glass-RPC planes" following a design similar to the glass-RPC detectors
developed by the CALICE Collaboration and used by the TOMUVOL experiment in the
context of volcano radiography, but with smaller active area (16 16
cm). The compact size makes it an attractive choice with respect to other
detectors previously employed for imaging on similar scales. An important
innovation in this design is that the detectors are sealed. This makes the
detector more portable and solves the usual safety and logistic issues for gas
detectors operated underground and/or inside small rooms. This paper provides
an overview on our guiding principles, the detector development and our
operational experiences. Drawing on the lessons learnt from the first
prototype, we also discuss our future direction for an improved second
prototype, focusing primarily on a recently adopted serigraphy technique for
the resistive coating of the glass plates.Comment: 8 pages, 7 figures, XV Workshop on Resistive Plate Chambers and
Related Detectors (RPC2020
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