Predistortion and enhancement of high-frequency peak limited MAC video signals

1986 ◽  
Vol 22 (16) ◽  
pp. 849 ◽  
Author(s):  
W.H. Dobbie
Keyword(s):  
High Frequency ◽  
High Frequency Peak ◽  
Video Signals ◽  
Frequency Peak

Positive phototaxis of the brine shrimp Artemia salina to monochromatic light

1978 ◽  
Vol 56 (4) ◽  
pp. 708-711 ◽  
Author(s):  
Ronald B. Aiken ◽  
Jack P. Hailman
Keyword(s):  
High Frequency ◽  
Brine Shrimp ◽  
Spectral Response ◽  
Monochromatic Light ◽  
Artemia Salina ◽  
Visual Pigments ◽  
High Frequency Peak ◽  
Crab Larva ◽  
Positive Phototaxis ◽  
Frequency Peak

The brine shrimp Artemia salina was photopositive in response to monochromatic light of approximately equal quantum intensity of two absolute levels. At the higher level (about 3 × 1014 quanta s−1 cm−2), the spectral response was bimodal with peaks near 560 and 700 THz frequency (about 535 and 430 nm wavelength, respectively), with an antimode at about 640 THz (465 nm). Response at the lower level (about 2 × 1014) was slightly lower and the midspectrum peak was shifted to higher frequencies (shorter wavelengths) and depressed relative to the high-frequency peak near 700 THz. The results suggest that positive phototaxis is mediated by two visual pigments, the high-frequency (short-wavelength) pigment being activated at lower illuminations than the midspectrum pigment. A similar bimodal response is known from a crab larva, but this appears to be the first anostracan crustacean to have been tested.

Bifurcation and chaos in high-frequency peak current mode Buck converter

2016 ◽  
Vol 25 (7) ◽  
pp. 070504 ◽  
Author(s):  
Chang-Yuan Chang ◽  
Xin Zhao ◽  
Fan Yang ◽  
Cheng-En Wu
Keyword(s):  
High Frequency ◽  
Current Mode ◽  
Buck Converter ◽  
Bifurcation And Chaos ◽  
High Frequency Peak ◽  
Peak Current ◽  
Frequency Peak

scholarly journals Similarities between the Effects of Prenatal Chlorpyrifos and Valproic Acid on Ultrasonic Vocalization in Infant Wistar Rats

2020 ◽  
Vol 17 (17) ◽  
pp. 6376
Author(s):  
Miguel Morales-Navas ◽  
Sergio Castaño-Castaño ◽  
Cristian Pérez-Fernández ◽  
Ainhoa Sánchez-Gil ◽  
María Teresa Colomina ◽  
...  
Keyword(s):  
Valproic Acid ◽  
Prenatal Exposure ◽  
High Frequency ◽  
Wistar Rats ◽  
Autism Spectrum ◽  
Emotional States ◽  
Good Tool ◽  
High Frequency Peak ◽  
Frequency Peak ◽  
Dependent Variables

Background: In recent years, ultrasonic vocalizations (USV) in pups has become established as a good tool for evaluating behaviors related to communication deficits and emotional states observed in autism spectrum disorder (ASD). Prenatal valproic acid (VPA) exposure leads to impairments and social behavior deficits associated with autism, with the effects of VPA being considered as a reliable animal model of ASD. Some studies also suggest that prenatal exposure to chlorpyrifos (CPF) could enhance autistic-like behaviors. Methods: In order to explore these similarities, in the present study we tested whether prenatal exposure to CPF at GD12.5–14.5 produces effects that are comparable to those produced by prenatal VPA exposure at GD12.5 in infant Wistar rats. Using Deep Squeek software, we evaluated total number of USVs, latency to the first call, mean call duration, principal frequency peak, high frequency peak, and type of calls. Results: Consistent with our hypothesis, we found that exposure to both CPF and VPA leads to a significantly smaller number of calls along with a longer latency to produce the first call. No significant effects were found for the remaining dependent variables. Conclusions: These results suggest that prenatal exposure to CPF could produce certain behaviors that are reminiscent of those observed in ASD patients.

Vagal Nerve Activity and the High Frequency Peak of the Heart Rate Variability

1999 ◽  
Vol 22 (5) ◽  
pp. 324-328 ◽  
Author(s):  
T. Yambe ◽  
S. Nanka ◽  
S. Kobayashi ◽  
A. Tanaka ◽  
M. Yoshizawa ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
High Frequency ◽  
Vagal Nerve ◽  
Nerve Activity ◽  
High Frequency Peak ◽  
Frequency Peak ◽  
Vagal Nerve Activity

SA nodal parasympathectomy delineates autonomic control of heart rate power spectrum

1991 ◽  
Vol 260 (3) ◽  
pp. H985-H988 ◽  
Author(s):  
D. C. Randall ◽  
D. R. Brown ◽  
R. M. Raisch ◽  
J. D. Yingling ◽  
W. C. Randall
Keyword(s):  
Heart Rate ◽  
Power Spectrum ◽  
High Frequency ◽  
Low Frequency ◽  
Sympathetic Nerves ◽  
Adrenergic Blockade ◽  
High Frequency Peak ◽  
Human Contact ◽  
Frequency Peak ◽  
Before And After

The purpose of this study was to quantify the relative roles of the canine cardiac parasympathetic and sympathetic nerves in controlling the distribution of power within the heart rate (HR) power spectrum using a highly selective surgical technique to parasympathectomize the SA node. DAta were recorded in awake dogs (n = 6) before and after the selective denervation; the animals were isolated from human contact and their behavior carefully monitored during the measurements. The average amplitude in the high-frequency (approximately 0.32 Hz) peak in the HR power spectrum decreased from a predenervation control of 2.68 +/- 1.54 (mean +/- SD, arbitrary units) to 0.07 +/- 0.06 (P less than 0.05). Corresponding resting HR increased from 80 +/- 9 to 106 +/- 16 beats/min (P less than 0.05). The low-frequency peak (approximately 0.02 Hz) also decreased from a control of 2.45 +/- 1.18 to a postparasympathectomy value of 1.25 +/- 0.92 (P less than 0.05). beta-Adrenergic blockade (propranolol, 1 mg/kg) further decreased the latter peak to 0.59 +/- 0.52 (P less than 0.05). These data directly demonstrate that the high-frequency peak of the HR power spectrum 1) results from parasympathetic control of SA nodal automaticity, while 2) the low-frequency peak reflects activity in both divisions of the autonomic nervous system.

Use of high-frequency peak in spectral analysis of heart rate increment to improve screening of obstructive sleep apnoea

2010 ◽  
Vol 15 (4) ◽  
pp. 837-843 ◽  
Author(s):  
Laurent Poupard ◽  
Isabelle Court-Fortune ◽  
Vincent Pichot ◽  
Florian Chouchou ◽  
Jean-Claude Barthélémy ◽  
...  
Keyword(s):  
Heart Rate ◽  
Spectral Analysis ◽  
Obstructive Sleep Apnoea ◽  
High Frequency ◽  
Sleep Apnoea ◽  
High Frequency Peak ◽  
Frequency Peak ◽  
Obstructive Sleep

A note on the secondary load cycle for a monopile in irregular deep water waves

2018 ◽  
Vol 849 ◽  
Author(s):  
Bjørn Hervold Riise ◽  
John Grue ◽  
Atle Jensen ◽  
Thomas B. Johannessen
Keyword(s):  
Deep Water ◽  
High Frequency ◽  
Water Waves ◽  
Load Cycle ◽  
Total Load ◽  
High Frequency Peak ◽  
Strongly Nonlinear ◽  
Secondary Load ◽  
Frequency Peak ◽  
Two Peaks

Laboratory experiments with a bottom hinged surface-piercing cylinder, exposed to irregular deep water waves, are used to investigate high-frequency forcing. The focus is on the secondary load cycle, a strongly nonlinear phenomenon regarding the wave load on a vertical cylinder, first identified by Grue et al. (1993 Preprint Series. Mechanics and Applied Mathematics, pp. 1–30. University of Oslo, available at http://urn.nb.no/URN:NBN:no-52740; 1994 Ninth International Workshop on Water Waves and Floating Bodies (ed. M. Ohkusu), pp. 77–81, available at http://iwwwfb.org). For a total of 2166 single wave events, the force above $3\unicode[STIX]{x1D714}$ (where $\unicode[STIX]{x1D714}$ is the governing wave frequency) is used to identify and split the strongly nonlinear forces into two peaks: a high-frequency peak closely correlated in time with the wave crest when the total load is positive and a high-frequency peak defining the secondary load cycle which occurs close in time to the wave zero downcrossing when the total load is negative. The two peaks are studied by regression analysis as a function of either the Keulegan–Carpenter number ($KC$) or the Froude number ($Fr$). Regarding the secondary load cycle, the best correlation is found with $Fr$. The speed of the travelling edge of the undisturbed wave approximates the fluid velocity. A threshold value separating between small and large forces is found for $KC\sim 4$–5, indicating effects of flow separation. Alternatively, the threshold occurs for $Fr\sim 0.3$–0.4, indicating local wave effects at the scale of the cylinder diameter. The findings suggest that both effects are present and important.

scholarly journals High-Frequency Internal Waves on the Oregon Continental Shelf

2007 ◽  
Vol 37 (7) ◽  
pp. 1956-1967 ◽  
Author(s):  
Eric A. D’Asaro ◽  
Ren-Chieh Lien ◽  
Frank Henyey
Keyword(s):  
Kinetic Energy ◽  
Internal Wave ◽  
Vertical Velocity ◽  
High Frequency ◽  
Internal Tide ◽  
High Energy ◽  
Small Contribution ◽  
High Frequency Peak ◽  
Frequency Peak ◽  
Peak Energy

Abstract Measurements of vertical velocity by isopycnal-following, neutrally buoyant floats deployed on the Oregon shelf during the summers of 2000 and 2001 were used to characterize internal gravity waves on the shelf using measurements of vertical velocity. The average spectrum of Wentzel–Kramers–Brillouin (WKB)-scaled vertical kinetic energy has the level predicted by the Garrett–Munk model (GM79), plus a narrow M2 tidal peak and a broad high-frequency peak extending from about 0.1N to N and rising a decade above GM79. The high-frequency peak varies in energy coherently with time across its entire bandwidth. Its energy is independent of the tidal energy. The energy in the “continuum” region between the peaks is weakly correlated with the level of the high-frequency peak energy and is independent of the tidal peak energy. The vertical velocity is not Gaussian but is highly intermittent, with a calculated kurtosis of 19. The vertical kinetic energy varies geographically. Low energy is found offshore and nearshore. The highest energy is found near a small seamount. High energy is found over the rough topography of Heceta Bank and near the shelf break. The highest energy occurs as packets of high-frequency waves, often occurring on the sharp downward phase of the M2 internal tide and called “tidal solibores.” A few isolated waves with high energy are also found. Of the 1-h periods with the highest vertical kinetic energy, 31% are tidal solibores, 8% are isolated waves, and the remainder of the periods appear unorganized. The two most energetic tidal solibores were examined in detail. As compared with the steady, propagating, two-dimensional, inviscid, internal-wave solutions to the equations of motion with no background shear [i.e., the Dubreil–Jacotin–Long (DJL) equation], all but the most energetic observed waveforms are too narrow for their height to be solitary waves. Despite the large near-N peak in vertical kinetic energy, the M2 internal tide contributes over 80% of the energy, ignoring near-inertial waves. The tidal solibores make a very small contribution, 0.5%, to the overall internal-wave energy.

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