Search results for "Oscillations"
showing 10 items of 238 documents
Wavelet analysis of baryon acoustic structures in the galaxy distribution
2011
Baryon Acoustic Oscillations (BAO) are a feature imprinted in the density field by acoustic waves travelling in the plasma of the early universe. Their fixed scale can be used as a standard ruler to study the geometry of the universe. BAO have been previously detected using correlation functions and power spectra of the galaxy distribution. In this work, we present a new method for the detection of the real-space structures associated with this feature. These baryon acoustic structures are spherical shells with a relatively small density contrast, surrounding high density central regions. We design a specific wavelet adapted to the search for shells, and exploit the physics of the process b…
The Baryon Oscillation Spectroscopic Survey of SDSS-III
2012
The Baryon Oscillation Spectroscopic Survey (BOSS) is designed to measure the scale of baryon acoustic oscillations (BAO) in the clustering of matter over a larger volume than the combined efforts of all previous spectroscopic surveys of large-scale structure. BOSS uses 1.5 million luminous galaxies as faint as i = 19.9 over 10,000 deg(2) to measure BAO to redshifts z < 0.7. Observations of neutral hydrogen in the Ly alpha forest in more than 150,000 quasar spectra (g < 22) will constrain BAO over the redshift range 2.15 < z < 3.5. Early results from BOSS include the first detection of the large-scale three-dimensional clustering of the Ly alpha forest and a strong detection from the Data R…
Hidden oscillations in SPICE simulation of two-phase Costas loop with non-linear VCO
2016
Simulation is widely used for analysis of Costas loop based circuits. However it may be a non-trivial task, because incorrect choice of integration parameters may lead to qualitatively wrong conclusions. In this work the importance of choosing appropriate parameters and simulation model is discussed. It is shown that hidden oscillations may not be found by simulation in SPICE, however it can be predicted by analytical methods. peerReviewed
Heterochromatin Networks: Topology, Dynamics, and Function (a Working Hypothesis)
2021
Open systems can only exist by self-organization as pulsing structures exchanging matter and energy with the outer world. This review is an attempt to reveal the organizational principles of the heterochromatin supra-intra-chromosomal network in terms of nonlinear thermodynamics. The accessibility of the linear information of the genetic code is regulated by constitutive heterochromatin (CHR) creating the positional information in a system of coordinates. These features include scale-free splitting-fusing of CHR with the boundary constraints of the nucleolus and nuclear envelope. The analysis of both the literature and our own data suggests a radial-concentric network as the main structural…
Exploring Frequency-Dependent Brain Networks from Ongoing EEG Using Spatial ICA During Music Listening
2020
Recently, exploring brain activity based on functional networks during naturalistic stimuli especially music and video represents an attractive challenge because of the low signal-to-noise ratio in collected brain data. Although most efforts focusing on exploring the listening brain have been made through functional magnetic resonance imaging (fMRI), sensor-level electro- or magnetoencephalography (EEG/MEG) technique, little is known about how neural rhythms are involved in the brain network activity under naturalistic stimuli. This study exploited cortical oscillations through analysis of ongoing EEG and musical feature during freely listening to music. We used a data-driven method that co…
An update to Hippocampome.org by integrating single-cell phenotypes with circuit function in vivo.
2021
Understanding brain operation demands linking basic behavioral traits to cell-type specific dynamics of different brain-wide subcircuits. This requires a system to classify the basic operational modes of neurons and circuits. Single-cell phenotyping of firing behavior during ongoing oscillations in vivo has provided a large body of evidence on entorhinal–hippocampal function, but data are dispersed and diverse. Here, we mined literature to search for information regarding the phase-timing dynamics of over 100 hippocampal/entorhinal neuron types defined in Hippocampome.org. We identified missing and unresolved pieces of knowledge (e.g., the preferred theta phase for a specific neuron type) a…
The oscillatory profile induced by the anxiogenic drug fg-7142 in the amygdala-hippocampal network is reversed by infralimbic deep brain stimulation:…
2021
Anxiety and depression exhibit high comorbidity and share the alteration of the amygdala-hippocampal-prefrontal network, playing different roles in the ventral and dorsal hippocampi. Deep brain stimulation of the infralimbic cortex in rodents or the human equivalent-the subgenual cingulate cortex-constitutes a fast antidepressant treatment. The aim of this work was: (1) to describe the oscillatory profile in a rodent model of anxiety, and (2) to deepen the therapeutic basis of infralimbic deep brain stimulation in mood disorders. First, the anxiogenic drug FG-7142 was administered to anaesthetized rats to characterize neural oscillations within the amygdala and the dorsoventral axis of the …
Up and Down States During Slow Oscillations in Slow-Wave Sleep and Different Levels of Anesthesia
2021
Slow oscillations are a pattern of synchronized network activity generated by the cerebral cortex. They consist of Up and Down states, which are periods of activity interspersed with periods of silence, respectively. However, even when this is a unique dynamic regime of transitions between Up and Down states, this pattern is not constant: there is a range of oscillatory frequencies (0.1–4 Hz), and the duration of Up vs. Down states during the cycles is variable. This opens many questions. Is there a constant relationship between the duration of Up and Down states? How much do they vary across conditions and oscillatory frequencies? Are there different sub regimes within the slow oscillation…
Influence of the channel design on the heat and mass exchange of induction channel furnace
2011
PurposeThe purpose of this paper is to present in‐depth numerical modelling of heat and mass exchange in industrial induction channel furnace (ICF).Design/methodology/approachThe turbulent heat and mass exchange in the melt is calculated using a three‐dimensional (3D) electromagnetic model and a 3D transient large eddy simulation method. The simulation model has been verified by flow velocity and temperature measurements, which were carried out using an industrial sized channel inductor operating with Wood's metal as a low temperature model melt.FindingsThe ICF is well‐established for melting, holding and casting in the metallurgical industry. But there are still open questions regarding th…
Hidden oscillations in aircraft flight control system with input saturation
2013
Abstract The presence of actuator saturation can dramatically degrade the system performance. Since the feedback loop is broken when the actuator saturates the unstable modes of the regulator may then drift to undesirable values. The consequences are that undesired nonlinear oscillations appear and that the settling time may unacceptably increase. Rigorous analysis of nonlinear aircraft models is a very difficult task, that is why a numerical simulation is often used as an analysis and design tool. In this paper difficulties of numerical analysis related to the existence of hidden oscillations in the aircraft control system are demonstrated.