Electronic Picture in the Normal States of High-Tc Superconductors: From the Optical Viewpoint

1989 ◽  
Vol 156 ◽  
Author(s):  
S. Tajima
Keyword(s):  
Liquid Metal ◽  
Frequency Spectrum ◽  
High Frequency ◽  
Fermi Liquid ◽  
Low Frequency ◽  
High Tc Superconductors ◽  
High Tc ◽  
Electronic Model ◽  
Normal States ◽  
Highly Correlated

ABSTRACTThe specific features of the optical spectra in the high-Tc Cu-oxides are discussed. The low-frequency spectral behavior can be explained by the highly correlated electronic model, whereas in the high-frequency spectrum the behavior of the Fermi liquid metal shows up.

Preferential acceleration of heavy ions from thermal velocities

1968 ◽  
Vol 46 (10) ◽  
pp. S638-S641 ◽  
Author(s):  
D. B. Melrose
Keyword(s):  
Frequency Spectrum ◽  
High Frequency ◽  
Heavy Ions ◽  
Crab Nebula ◽  
Low Frequency ◽  
High Frequency Waves ◽  
Hydromagnetic Waves ◽  
The Crab Nebula ◽  
Low Frequency Waves

The acceleration of ions from thermal velocities is analyzed to determine conditions under which heavy ions can be preferentially accelerated. Two accelerating mechanisms involving high-and low-frequency hydromagnetic waves respectively are considered. Preferential acceleration of heavy ions occurs for high-frequency waves if the frequency spectrum falls off faster than (frequency)−1. For the low-frequency waves heavy ions are less effectively accelerated than lighter ions. However, very heavy ions can be preferentially accelerated, the abundances of the very heavy ions being enhanced by a factor Ai over the thermal abundances. Acceleration of ions in the envelope of the Crab nebula is considered as an example.

Heart rate at 4 s after the onset of exercise in endurance-trained men

2014 ◽  
Vol 92 (6) ◽  
pp. 476-480 ◽  
Author(s):  
Divanei Zaniqueli ◽  
Elis Aguiar Morra ◽  
Eduardo Miranda Dantas ◽  
Marcelo Perim Baldo ◽  
Luciana Carletti ◽  
...  
Keyword(s):  
Heart Rate ◽  
Frequency Spectrum ◽  
High Frequency ◽  
Sinus Node ◽  
Low Frequency ◽  
Spectral Indices ◽  
High Frequency Band ◽  
Band Ratio ◽  
Endurance Runners ◽  
Vagal Influence

It has been suggested that the increase in heart rate (HR) at the onset of exercise is caused by vagal withdrawal. In fact, endurance runners show a lower HR in maximum aerobic tests. However, it is still unknown whether endurance runners have a lower HR at 4 s after the onset of exercise (4th-sec-HR). We sought to measure the HR at the onset of the 4 s exercise test (4-sET), clarifying its relationship to heart rate variability (HRV), spectral indices, and cardiac vagal index (CVI) in endurance runners (ER) and healthy untrained controls (CON). HR at 4th-sec-HR, CVI, and percent HR increase during exercise were analyzed in the 4-sET. High frequency spectrum (HF-nu), low frequency spectrum (LF-nu), and low frequency/high frequency band ratio (LF/HF) were analyzed from the HRV. ER showed a significantly higher HF, and both a lower LF and LF/HF ratio compared with the CON. ER presented a significantly lower 4th-sec-HR, although neither CVI nor HR increases during exercise were statistically different from the CON. In conclusion, ER presented a lower 4th-sec-HR secondary to increased vagal influence over the sinus node. CVI seems to be too weak to use for discriminating individuals with respect to the magnitude of HR vagal control.

scholarly journals Краевые колебания нанолент графана

2018 ◽  
Vol 60 (5) ◽  
pp. 1029
Author(s):  
А.В. Савин
Keyword(s):  
Force Field ◽  
Frequency Spectrum ◽  
High Frequency ◽  
Low Frequency ◽  
Dispersion Curves ◽  
Linear Vibrations ◽  
The Mean

AbstractUsing the COMPASS force field, natural linear vibrations of graphane (graphene hydrogenated on both sides) nanoribbons are simulated. The frequency spectrum of a graphane sheet consists of three continuous intervals (low-frequency, mid-frequency, and narrow high-frequency) and two gaps between them. The construction of dispersion curves for nanoribbons with a zigzag and chair structure of the edges show that the frequencies of edge vibrations (edge phonons) can be present in the gaps of the frequency spectrum. In the first type of nanoribbons, two dispersion curves are in the low-frequency gap of the spectrum and four dispersion curves in the second gap. These curves correspond to phonons moving only along the nanoribbon edges (the mean depth of their penetration toward the nanoribbon center does not exceed 0.15 nm).

scholarly journals Joule heating and high frequency nonlinear effects in the surface impedance of high Tc superconductors

2009 ◽  
Vol 106 (2) ◽  
pp. 023912 ◽  
Author(s):  
Julien Kermorvant ◽  
Cornelis Jacominus van der Beek ◽  
Jean-Claude Mage ◽  
Bruno Marcilhac ◽  
Yves Lemaître ◽  
...  
Keyword(s):  
Joule Heating ◽  
Surface Impedance ◽  
High Frequency ◽  
Nonlinear Effects ◽  
High Tc Superconductors ◽  
High Tc
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