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Suppression of In Vitro α/θ Field Oscillations by Gap Junction Blockers (A) LGN field recording in the presence of 125 μM trans-ACPD showing synchronized activity at ∼8 Hz (top trace). Application of glycyrrhizic acid (GZA) (100 μM) has no effect. However, application of the gap junction blocker 18β-glycyrrhetinic acid (18β-GA) (100 μM) abolishes the oscillation. Synchronized activity returns following washout of 18β-GA (bottom trace). (B) LGN field oscillation at ∼3 Hz recorded in the presence of 100 μM trans-ACPD (top trace). The oscillation is suppressed by 100 μM carbenoxolone (CBX) (bottom trace). (C) LGN field recording in the presence of 125 μM trans-ACPD showing synchronized activity at ∼7–9 Hz (top trace). Intracellular alkalinization via bath application of trimethylamine (TMA) (20 mM) greatly enhances the field oscillation, an effect that is reversibly inhibited by the gap junction blocker octanol (0.5 mM). (D and E) Summary of the effects of various gap junction modulators on the peak power and frequency of α/θ field oscillations, respectively. 10 μM CNQX, 100 μM DL-AP5, 30 μM bicuculline, and 10 μM CGP56999A were present during all experiments depicted in this figure. *p < 0.01; **p < 0.001. ... Properties and Mechanisms of HT Bursting in TC Neurons (A) HT bursting at different levels of injected DC current showing an increase in interburst frequency with depolarization. TTX (1 μM) blocks the fast action potentials but leaves an oscillatory activity consisting of repetitive HT spikes intact. (B) Plot of interburst frequency versus mean number of action potentials per HT burst (•) shows an identical profile to that for bursts recorded extracellularly during in vitro α/θ oscillations (□) (see Figure 2D). (C) Plots of injected DC current versus interburst frequency before (○) and after (•) TTX application. (D) A TC neuron in the presence of trans-ACPD (125 μM) and TTX (1 μM) exhibits repetitive HT spikes that are reversibly abolished by 300 μM Ni2+. Sections marked by continuous lines are enlarged on the right. (E) In some TC neurons, HT spikes are evident prior to TTX application (red line). (F) The fast ADP is highly sensitive to TTX treatment and is abolished prior to a full block of the action potential. (G) The ADP is unaffected by intracellular Ca2+ chelation following a 1 hr recording with an EGTA-filled electrode (50 mM). 100–125 μM trans-ACPD was present during all experiments depicted in this figure. Further information regarding the ionic mechanisms of HT bursting is shown in Supplemental Figure S5 at http://www.neuron.org/cgi/content/full/42/2/253/DC1. ... α, θ, and Slow Waves in the LGN In Vitro and In Vivo and Their Dependence on mGluR1a (A) Extracellular field recording in the LGN slice showing a lack of activity in control conditions (top trace). 150 μM trans-ACPD induces a robust oscillation at ∼8 Hz with a characteristic sinusoidal appearance and seemingly random waxing and waning nature. This oscillation slows to ∼4 Hz when the concentration of trans-ACPD is reduced to 100 μM and is replaced by slow waves at oscillations is observed in the LGN in vivo as arousal shifts from a state of relaxed wakefulness (α waves), through drowsiness (θ waves), to deep sleep (slow waves). Again, all data were taken from the same LGN recording site. (C) Histograms showing the mean frequency of in vitro α/θ oscillations under various conditions and their dependence on mGluR1a. (D and E) Histogram showing the effect of i.v. injection of mGluR antagonists at various doses on in vivo α rhythm density and frequency of K spindle complexes in LGN field recordings. **p < 0.001; ***p < 0.0001. Numbers of observations for the data presented in (C)–(E) are given in the text. ... Properties of Burstlets in TC Neurons (A) Activity of a LGN TC neuron exhibiting complex burstlets at various levels of injected DC current. Burstlet frequency increases with increasing depolarization eventually triggering full-blown HT bursts on every cycle (top trace). Events marked 1, 2, and 3 are enlarged on the right. The top right trace (1) shows an enlargement of a burstlet leading to a full-blown HT burst. The trace below (2) shows a burstlet leading to a single action potential. The bottom trace (3) shows an isolated burstlet. (B) Plot of injected DC current versus interburstlet frequency (○) and peak burstlet amplitude (■). (C) Averaged interspikelet interval patterns for burstlets comprising 2, 3, and 4 spikelets are similar to the ISI patterns of intra- and extracellularly recorded HT bursts (averaged together and plotted as □). (D) Plot of interburstlet frequency versus number of spikelets per burstlet (•) shows identical properties to the average values for pooled intra- and extracellularly recorded HT bursts (□). (E) Activity of the neuron depicted in (A) over a longer time course and at a more depolarized level. Sections marked F and G are expanded below. (F) During this period, the voltage waveform between HT bursts is smooth, suggesting that HT bursts and burstlets are in phase (see [A], top trace). The trace on the right shows the averaged interburst interval. (G) During this period, the voltage waveform between HT bursts is interrupted by small depolarizations (arrows) that indicate a disruption of the phase relationship between HT bursts and burstlets. The averaged interburst interval (right) shows an antiphase depolarization between the bursts (arrow). ... Neuronal Activity in the LGN Related to α/θ Oscillations In Vitro and α and θ Rhythms In Vivo (A) Simultaneous field and single-unit recording in the LGN in vitro showing correlated activity with both α (upper traces; 150 μM trans-ACPD) and θ (lower traces; 100 μM trans-ACPD) field oscillations. The sections marked by the continuous bars are enlarged on the right. (B) Simultaneous field and single-unit recording in the LGN in vivo showing correlated activity with both α (upper traces) and θ (lower traces) field oscillations. The sections marked by the continuous bars are enlarged on the right. (C) Plots showing the similarity in the averaged ISI patterns for spike bursts correlated to α and θ activity in vivo (•) and in vitro (□). (D) Plots of interburst frequency versus number of spikes per burst are similar for in vivo (•) and in vitro (□) single-unit recordings during α and θ activity. (E) Plots showing the similarity in the averaged ISI patterns for spike bursts correlated to slow wave activity in vivo (•) and in vitro (□). Note the contrasting pattern to that occurring during α and θ rhythms (C). Additional information regarding the neuronal activity correlated with in vivo and in vitro slow waves is shown in Supplemental Figure S2 at http://www.neuron.org/cgi/content/full/42/2/253/DC1.
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two-frequency pendulum... Analysis of the rotative potential of two-frequency oscillation of water molecule.pdf
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Digitally Controlled Oscillators
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electronic oscillators, pulse generators and multivibrators... oscillators... oscillators - noise
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n/a
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Silicon Qubits
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low frequency... forced oscillation
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A program of research has been undertaken to examine the interaction between vortex shedding and the galloping type oscillation which square cylinders are subject to when immersed in a water stream. It is possible that the fluctuating force from the vortex shedding could quench the galloping oscillation if it acts as a forced oscillation (independent of cylinder motion). An experiment was designed where a square cylinder with one degree of freedom could oscillate transversely to the water flow. The amplitude and frequency of the cylinder oscillation were measured. By using a hot film anemometer spectra of the fluctuating velocity in the wake were taken to determine what frequencies vortex shedding occurred at. The results show that for velocities greater than the resonant velocity the galloping oscillation is dominant and the cylinder motion controls the frequencies of the wake. For velocities less than the resonant velocity no galloping occurs and the vortex shedding seems to control any cylinder motion which occurs. To explain this type of response a mathematical model has been constructed. The model is a set of two coupled self excited oscillators} one with the characteristics of the galloping oscillation and the other with the characteristics of the fluctuating lift force from the vortex shedding. Using the model some aspects of the observed interaction are explained.
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