scholarly journals Frequency Characteristics of Retinal Neurons in the Carp

1974 ◽  
Vol 63 (2) ◽  
pp. 214-234 ◽  
Author(s):  
Jun-Ichi Toyoda
Keyword(s):  
Light Intensity ◽  
Cutoff Frequency ◽  
Low Frequency ◽  
Amacrine Cells ◽  
Frequency Characteristics ◽  
Horizontal Cells ◽  
Lateral Interaction ◽  
Retinal Neurons ◽  
Low Frequencies ◽  
Modulated Light

Frequency characteristics of various retinal neurons in the carp were studied using sinusoidally modulated light as an input. They were affected by both intensity and pattern of illumination. In the horizontal cells, in which the effect of light intensity was studied most extensively, an increase in the light intensity brought about a decrease of the gain, which was more marked at lower frequencies, resulting in a shift of cutoff frequency towards higher frequencies and in a slight low frequency attenuation. A decrease in the area illuminated had an effect similar to a decrease in the light intensity. In the receptor, the low frequency attenuation was not apparent even at high light intensities. The adaptation process in receptors was not sufficient to explain the low frequency attenuation in the horizontal cells, and a possible contribution of negative feedback from horizontal cells to receptors was suggested. In the bipolar cell, the lateral interaction played an important role. An increase in an area resulted in the suppression of the response at low frequencies where the phases of the center and the surround responses were opposed, but in the augmentation near 5 Hz where the two responses were in phase. In amacrine cells, a low frequency attenuation and a phase advance at low frequencies were very prominent, and were considered to be due mainly to a process designated here as the neural adaptation.

Preamplifier With Ultra Low Frequency Cutoff for Infrasonic Condenser Microphone

2012 ◽  
Author(s):  
Rasmus Trock Kinnerup ◽  
Arnold Knott ◽  
Ole Cornelius Thomsen ◽  
Kresten Marbjerg ◽  
Per Rasmussen
Keyword(s):  
Input Impedance ◽  
Dynamic Range ◽  
Cutoff Frequency ◽  
Low Frequency ◽  
Input Resistance ◽  
Bias Current ◽  
Microphone Signal ◽  
Low Frequencies ◽  
Pass Filter ◽  
Condenser Microphone

Measuring infrasonic sound sets high requirements on the instruments used. Typically the measurement chain consists of a microphone and a preamplifier. As the input resistance of the preamplifier forms a high pass filter with the capacitance of the microphone in the picofarad range, measuring ultra low frequencies becomes a challenge. The electric preamplifier presented in this paper together with a prepolarized condenser microphone form a measurement system. The developed preamplifier connects the microphone signal directly to the input of an operational amplifier with ultra high input impedance. The bias current for the preamplifier further complicates the signal amplification. A configuration of two diode-connected FETs provide the input bias current. The resulting input impedance of nearly 1 TΩ yields a total lower limiting −3 dB cutoff frequency of 8 mHz and a dynamic range of 95 dB. Being able to measure down to ultra low frequencies in the infrasonic frequency range will aid actors in the debate on wind turbine noise. Sonic booms from supersonic flights include frequencies down to 10 mHz and the preamplifier proposed in this paper will aid scientists trying to modify the N-shaped shock wave at high level which prohibits flights in land zones.

Mapping photoreceptor and postreceptoral labelling patterns using a channel permeable probe (agmatine) during development in the normal and RCS rat retina

2002 ◽  
Vol 19 (1) ◽  
pp. 61-70 ◽  
Author(s):  
MICHAEL KALLONIATIS ◽  
GUIDO TOMISICH ◽  
JOHN W. WELLARD ◽  
LISA E. FOSTER
Keyword(s):  
Amacrine Cells ◽  
Horizontal Cells ◽  
Retinal Neurons ◽  
Inner Retina ◽  
Strong Signal ◽  
Rcs Rat ◽  
Sequential Development ◽  
Nuclear Labelling ◽  
Multiple Samples ◽  
Neurochemical Development

The aim of this study was to determine whether agmatine, a channel permeable probe, can identify photoreceptor dysfunction in the Royal College of Surgeons (RCS) retina at an earlier stage to that shown by apoptosis or anatomical markers, and also characterize the neurochemical development of the inner retina in the normal and degenerating rat. We used isolated retinas at different ages incubated in physiological media containing agmatine. Subsequently, postembedding immunocytochemistry was used to determine the number of labelled photoreceptors and the labelling pattern within postreceptoral neurons. Agmatine labelling patterns revealed a sequential development of retinal neurons beginning at postnatal day (PND)11/12 with most horizontal cells, a few ganglion and amacrine cells, showing a strong signal. The neurochemical development progressed rapidly, and reflects to a large part the known distribution of glutamate receptors, with inner nuclear labelling being evident by PND14, continuing with the same pattern of labelling in adulthood for the control retina. The RCS retina showed markedly reduced agmatine labelling in the inner retina at PND20. A rapid increase in photoreceptor AGB labelling was evident during the degeneration phase. Multiple samples at PND14 and PND16 confirmed a significant increase of labelled photoreceptors in the RCS retina.

Quantitative Analysis of Rogowski CT Frequency Characteristics

2013 ◽  
Vol 860-863 ◽  
pp. 2168-2176
Author(s):  
Zong Jie Liu ◽  
Xiao Xin Chen ◽  
Fang Yuan Jin ◽  
Ling Ming Kong ◽  
Chong Feng Tian ◽  
...  
Keyword(s):  
Cutoff Frequency ◽  
Current Transformer ◽  
Frequency Characteristics ◽  
Core Material ◽  
Pass Band ◽  
Power Cables ◽  
Low Frequencies ◽  
Coil Winding ◽  
A Current ◽  
Lower Cutoff

Partial discharges in power cables will generate small currents with low frequencies in the ground cords. In cable PD online monitoring systems, CTs are usually used to obtain such PD signals. In this paper, by derivations based on theories of wave propagation, the frequency characteristics of Rogowski CTs (RCTs) and the effects of transformer parameters (size, core material, etc.) on its pass band B, sensitivity H(jω0), the lower cutoff frequency fL is acquired. The feasibility of such derivations is verified by experiments. By conducting comparative experiments, the effect of the use of screening box and the way of coil winding on the performance of a current transformer is acquired. A feasible plan to improve the frequency characteristics of CTs is presented, in order to acquire more stable gain and better anti-interference ability within their pass band.

NOISE CHARACTERISTICS OF 340 nm AND 280 nmGaN-BASED LIGHT EMITTING DIODES

2004 ◽  
Vol 14 (03) ◽  
pp. 702-707
Author(s):  
SHAYLA SAWYER ◽  
SERGEY L. RUMYANTSEV ◽  
NEZIH PALA ◽  
MICHAEL S. SHUR ◽  
YURIY BILENKO ◽  
...  
Keyword(s):  
Light Intensity ◽  
Quality Factor ◽  
Light Emitting Diodes ◽  
Low Frequency ◽  
Low Frequencies ◽  
Light Emitting ◽  
Visible Wavelength ◽  
Noise Characteristics ◽  
Uv Leds ◽  
Halogen Lamps

Low frequency fluctuations in light intensity of 340 nm and 280 nm GaN -based light emitting diodes (LEDs) are compared with noise properties of other commercially available UV and visible wavelength LEDs and halogen lamps. At low frequencies, LEDs can exhibit lower levels of noise than halogen lamps. An LED noise quality factor β is estimated for the UV LEDs.

scholarly journals Acoustic wave propagation in rivers: an experimental study

2018 ◽  
Author(s):  
Thomas Geay ◽  
Ludovic Michel ◽  
Sébastien Zanker ◽  
James Robert Rigby
Keyword(s):  
Acoustic Wave ◽  
Water Depth ◽  
Acoustic Waves ◽  
Cutoff Frequency ◽  
Low Frequency ◽  
Attenuation Coefficients ◽  
Low Frequencies ◽  
River Bed ◽  
Bed Slope ◽  
Passive Acoustic

Abstract. This research has been conducted to develop the use of Passive Acoustic Monitoring (PAM) in rivers, a surrogate method for bedload monitoring. PAM consists in measuring the underwater noise naturally generated by bedload particles when impacting the river bed. Monitored bedload acoustic signals depend on bedload characteristics (e.g. grain size distribution, fluxes) but are also affected by the environment in which the acoustic waves are propagated. This study focuses on the determination of propagation effects in rivers. An experimental approach has been conducted in several streams to estimate acoustic propagation laws in field conditions. It is found that acoustic waves are differently propagated according to their frequency. As reported in other studies, acoustic waves are affected by the existence of a cutoff frequency in the kHz region. This cutoff frequency is inversely proportional to the water depth: larger water depth enables a better propagation of the acoustic waves at low frequency. Above the cutoff frequency, attenuation coefficients are found to increase linearly with frequency. The power of bedload sounds is more attenuated at higher frequencies than at low frequencies which means that, above the cutoff frequency, sounds of big particles are better propagated than sounds of small particles. Finally, it is observed that attenuation coefficients are variable within 2 orders of magnitude from one river to another. Attenuation coefficients are compared to several characteristics of the river (e.g. bed slope, bed rugosity). It is found that acoustic waves are better propagated in rivers characterised by smaller bed slopes. Bed rugosity and the presence of air bubbles in the water column are suspected to constrain the attenuation of acoustic wave in rivers.

scholarly journals Acoustic wave propagation in rivers: an experimental study

2019 ◽  
Vol 7 (2) ◽  
pp. 537-548 ◽  
Author(s):  
Thomas Geay ◽  
Ludovic Michel ◽  
Sébastien Zanker ◽  
James Robert Rigby
Keyword(s):  
Grain Size ◽  
Acoustic Wave ◽  
Water Depth ◽  
Acoustic Waves ◽  
Cutoff Frequency ◽  
Low Frequency ◽  
Attenuation Coefficients ◽  
Low Frequencies ◽  
River Bed ◽  
Bed Roughness

Abstract. This research has been conducted to develop the use of passive acoustic monitoring (PAM) in rivers, a surrogate method for bedload monitoring. PAM consists in measuring the underwater noise naturally generated by bedload particles when impacting the river bed. Monitored bedload acoustic signals depend on bedload characteristics (e.g., grain size distribution, fluxes) but are also affected by the environment in which the acoustic waves are propagated. This study focuses on the determination of propagation effects in rivers. An experimental approach has been conducted in several streams to estimate acoustic propagation laws in field conditions. It is found that acoustic waves are differently propagated according to their frequency. As reported in other studies, acoustic waves are affected by the existence of a cutoff frequency in the kilohertz region. This cutoff frequency is inversely proportional to the water depth: larger water depth enables a better propagation of the acoustic waves at low frequency. Above the cutoff frequency, attenuation coefficients are found to increase linearly with frequency. The power of bedload sounds is more attenuated at higher frequencies than at low frequencies, which means that, above the cutoff frequency, sounds of big particles are better propagated than sounds of small particles. Finally, it is observed that attenuation coefficients are variable within 2 orders of magnitude from one river to another. Attenuation coefficients are compared to several characteristics of the river (e.g., bed slope, surface grain size). It is found that acoustic waves are better propagated in rivers characterized by smaller bed slopes. Bed roughness and the presence of air bubbles in the water column are suspected to constrain the attenuation of acoustic wave in rivers.

Similar effects of carbachol and dopamine on neurons in the distal retina of the tiger salamander

1995 ◽  
Vol 12 (3) ◽  
pp. 443-455 ◽  
Author(s):  
William A. Hare ◽  
W. Geoffrey Owen
Keyword(s):  
Dopamine Release ◽  
Light Adaptation ◽  
Amacrine Cells ◽  
Bipolar Cells ◽  
Horizontal Cells ◽  
D1 Receptors ◽  
Ambystoma Tigrinum ◽  
Tiger Salamander ◽  
Retinal Neurons ◽  
D2 Dopamine Receptors

AbstractThough there is considerable evidence that dopamine is an important retinal neuromodulator that mediates many of the changes in the properties of retinal neurons that are normally seen during light adaptation, the mechanism by which dopamine release is controlled remains poorly understood. In this paper, we present evidence which indicates that dopamine release in the retina of the tiger salamander, Ambystoma tigrinum, is driven excitatorily by a cholinergic input. We compared the effects of applying carbachol to those of dopamine application on the responses of rods, horizontal cells, and bipolar cells recorded intracellularly from the isolated, perfused retina of the tiger salamander. Micromolar concentrations of dopamine reduced the amplitudes of rod responses throughout the rods' operating range. The ratio of amplitudes of the cone-driven to rod-driven components of the responses of both horizontal and bipolar cells was increased by activation of both D1 and D2 dopamine receptors. Dopamine acted to uncouple horizontal cells and also off-center bipolar cells, the mechanism in the case of horizontal cells depending only upon activation of D1 receptors. Carbachol, a specific cholinomimetic, applied in five- to ten-fold higher concentrations, produced effects that were essentially identical to those of dopamine. These effects of carbachol were blocked by application of specific dopamine blockers, however, indicating that they are mediated secondarily by dopamine. We propose that the dopamine-releasing amacrine cells in the salamander are under the control of cells, probably amacrine cells, which secrete acetylcholine as their transmitter.

scholarly journals The somal patterning of the AII amacrine cell mosaic in the mouse retina is indistinguishable from random simulations matched for density and constrained by soma size

2018 ◽  
Vol 35 ◽  
Author(s):  
PATRICK W. KEELEY ◽  
BENJAMIN E. REESE
Keyword(s):  
Amacrine Cell ◽  
Amacrine Cells ◽  
Bipolar Cells ◽  
Horizontal Cells ◽  
Mouse Retina ◽  
Retinal Neurons ◽  
Soma Size ◽  
Aii Amacrine Cells ◽  
Aii Amacrine ◽  
Cholinergic Amacrine Cells

AbstractThe orderly spacing of retinal neurons is commonly regarded as a characteristic feature of retinal nerve cell populations. Exemplars of this property include the horizontal cells and the cholinergic amacrine cells, where individual cells minimize the proximity to like-type neighbors, yielding regularity in the patterning of their somata. Recently, two types of retinal bipolar cells in the mouse retina were shown to exhibit an order in their somal patterning no different from density-matched simulations constrained by soma size but being otherwise randomly distributed. The present study has now extended this finding to a type of retinal amacrine cell, the AII amacrine cell. Voronoi domain analysis revealed the patterning in the population of AII amacrine somata to be no different from density-matched and soma-size-constrained random simulations, while analysis of the density recovery profile showed AII amacrine cells to exhibit a minimal intercellular spacing identical to that for those random simulations: AII amacrine somata were positioned side-by-side as often as chance would predict. Regularity indexes and packing factors (PF) were far lower than those achieved by either the horizontal cells or cholinergic amacrine cells, with PFs also being comparable to those derived from the constrained random simulations. These results extend recent findings that call into question the widespread assumption that all types of retinal neurons are assembled as regular somal arrays, and have implications for the way in which AII amacrine cells must distribute their processes to ensure a uniform coverage of the retinal surface.

scholarly journals Earless toads sense low frequencies but miss the high notes

2017 ◽  
Vol 284 (1864) ◽  
pp. 20171670 ◽  
Author(s):  
Molly C. Womack ◽  
Jakob Christensen-Dalsgaard ◽  
Luis A. Coloma ◽  
Juan C. Chaparro ◽  
Kim L. Hoke
Keyword(s):  
High Frequency ◽  
Species Differences ◽  
Low Frequency ◽  
Auditory Brainstem ◽  
Low Frequencies ◽  
Hearing Sensitivity ◽  
Sensory Pathways ◽  
Airborne Sound ◽  
Vibrational Sensitivity ◽  
Species Specific

Sensory losses or reductions are frequently attributed to relaxed selection. However, anuran species have lost tympanic middle ears many times, despite anurans' use of acoustic communication and the benefit of middle ears for hearing airborne sound. Here we determine whether pre-existing alternative sensory pathways enable anurans lacking tympanic middle ears (termed earless anurans) to hear airborne sound as well as eared species or to better sense vibrations in the environment. We used auditory brainstem recordings to compare hearing and vibrational sensitivity among 10 species (six eared, four earless) within the Neotropical true toad family (Bufonidae). We found that species lacking middle ears are less sensitive to high-frequency sounds, however, low-frequency hearing and vibrational sensitivity are equivalent between eared and earless species. Furthermore, extratympanic hearing sensitivity varies among earless species, highlighting potential species differences in extratympanic hearing mechanisms. We argue that ancestral bufonids may have sufficient extratympanic hearing and vibrational sensitivity such that earless lineages tolerated the loss of high frequency hearing sensitivity by adopting species-specific behavioural strategies to detect conspecifics, predators and prey.

A waveform inversion technique for measuring elastic wave attenuation in cylindrical bars

Geophysics ◽  
1992 ◽  
Vol 57 (6) ◽  
pp. 854-859 ◽  
Author(s):  
Xiao Ming Tang
Keyword(s):  
Elastic Wave ◽  
Wave Attenuation ◽  
Waveform Inversion ◽  
Finite Size ◽  
Low Frequency ◽  
Frequency Range ◽  
Multiple Reflections ◽  
Low Frequencies ◽  
The Time Domain ◽  
Attenuation Values

A new technique for measuring elastic wave attenuation in the frequency range of 10–150 kHz consists of measuring low‐frequency waveforms using two cylindrical bars of the same material but of different lengths. The attenuation is obtained through two steps. In the first, the waveform measured within the shorter bar is propagated to the length of the longer bar, and the distortion of the waveform due to the dispersion effect of the cylindrical waveguide is compensated. The second step is the inversion for the attenuation or Q of the bar material by minimizing the difference between the waveform propagated from the shorter bar and the waveform measured within the longer bar. The waveform inversion is performed in the time domain, and the waveforms can be appropriately truncated to avoid multiple reflections due to the finite size of the (shorter) sample, allowing attenuation to be measured at long wavelengths or low frequencies. The frequency range in which this technique operates fills the gap between the resonant bar measurement (∼10 kHz) and ultrasonic measurement (∼100–1000 kHz). By using the technique, attenuation values in a PVC (a highly attenuative) material and in Sierra White granite were measured in the frequency range of 40–140 kHz. The obtained attenuation values for the two materials are found to be reliable and consistent.

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