Sharp wave ripples (high frequency events which occur in the CA1 hippocampal region of the brain) are detected using algorithms which automatically threshold the data at certain voltage values. Typically, detection algorithms use the same threshold throughout the entire voltage trace. The problem with this method is that the amplitude distribution of the noise is not constant in time; algorithm...

Fries et al. (1999), hereafter referred to as FBW, present interesting experimental data showing that biogenic mounds, formed by the conveyor-belt feeding polychaete Cistenides (Pectinaria) gouldii, can be reshaped into asymmetric bedforms at bed shear stresses below the Shields threshold of sediment movement. The ®nal geometry of the current ripples was found to depend on the spatial density o...

In DSP based IQ modulators generating CPFSK signals, departures from a flat-magnitude, linear phase frequency response in the pass bands of analogue reconstruction filters in the I and Q channels cause ripples in the modulator output signal envelope. These ripples then produce undesirable side-lobes in the output signal spectrum when the signal passes through non-linear elements in the transmis...

This paper presents a direct torque control (DTC) of induction motor drive (IMD) using Different levels of Cascade Multilevel DVR. The DTC is one of the most excellent strategies of flux ripples control and torque of IMD. The main drawback of the DTC of IMD using conventional PI controller based SR is high torque, stator flux ripples and speed of IMD is decreasing under transient and steady sta...

Low-voltage fast (LVF)- and hypersynchronous (HYP)-seizure onset patterns can be recognized in the EEG of epileptic animals and patients with temporal lobe epilepsy. Ripples (80-200 Hz) and fast ripples (250-500 Hz) have been linked to each pattern, with ripples predominating during LVF seizures and fast ripples predominating during HYP seizures in the rat pilocarpine model. This evidence led u...

18 Granule ripples at Great Sand Dunes National Park and Preserve (GSDNPP) were observed with 19 inexpensive digital timelapse cameras over a 70-day period in winter 2010-2011. The ripples migrated 20 during a handful of discrete events visible ripple movement occurred on only 11 days during the 21 observation period. The movement conditions are documented with hourly and 15-minute records 22 f...

I report experiments on the observation of sand ripples on the Quattani dunes in Egypt using an inexpensive ($150) digital timelapse camera. Simple ripples in the fine sand had a wavelength of 10cm and propagated downwind (windspeed ~10m/s) at a speed of ~3cm/minute, and Y-junction defects moved one wavelength forward in the propagating ripple pattern over ~6 minutes. This defect propagation sp...

In a conventional three phase Brushless DC machine with 120° electrical conduction, Harmonics and commutation torque ripple occurs because of changeover of load current from one phase to another at every 60 electrical degrees. This paper presents techniques for diminishing the harmonics and torque ripples in sensor Brushless DC motor. This torque ripple reduction techniques based on voltage con...

High-frequency cortical activity, particularly in the 250-600 Hz (fast ripple) band, has been implicated in playing a crucial role in epileptogenesis and seizure generation. Fast ripples are highly specific for the seizure initiation zone. However, evidence for the association of fast ripples with epileptic foci depends on animal models and human cases with substantial lesions in the form of hi...

Sharp wave-associated ∼200-Hz ripple oscillations in the hippocampus have been implicated in the consolidation of memories. However, knowledge on mechanisms underlying ripples is still scarce, in particular with respect to synaptic involvement of specific cell types. Here, we used cell-attached and whole-cell recordings in vitro to study activity of pyramidal cells and oriens-lacunosum-molecula...