The Role and Controversies of Electroencephalogram in Focal versus Generalized Epilepsy

As early in 1935, Gibbs et al described electroencephalogram (EEG) features of large slow waves seen in “petit mal” seizures and change in background rhythm to a higher frequency, greater amplitude pattern in “grand mal” seizures. Studies have shown many typical EEG features in focal onset as well as generalized epilepsies.2 3 It is usually easy to delineate focal epilepsy cases when EEG onset of seizures is clear as seen in Benign focal epileptiform discharges of childhood.4 However, it is not uncommon to see cases where epileptiform discharges are not very clear. For example, there can be secondary bilateral synchrony or generalized onset of epileptiform discharges in some cases of focal epilepsy5 and nongeneralized EEG features is cases of generalized epilepsy like absence seizures.6 The awareness of occurrence of focal clinical and EEG features in generalized epilepsy is particularly important to help to select appropriate AEDs and also to avoid inappropriate consideration for epilepsy surgery.7 Lüders et al8 have shown that multiple factors like electroclinical seizure evolution, neuroimaging (both functional and anatomical) have to be analyzed in depth before defining an epileptic syndrome. Here, we are providing few examples of different situations where it is still mysterious to figure out focal onset seizures with secondary generalization versus primary generalized epilepsy.

New data on the bush-cricket Montana medvedevi (Orthoptera: Tettigoniidae), critically endangered in Europe (EU 28), and a comparison of its song with all known song patterns within the genus

Montana medvedevi is reported for the first time from Serbia. New information about the distribution, morphology and song of this species is discussed. The song of M. medvedevi is different from that of all other members of the genus, all figured for comparison. Montana is quite diverse regarding the amplitude pattern of the calling song of its members (known in 15 species). Surprisingly, some Montana species seem to have two song patterns, one produced during the day and one at night.

The Key Mechanics Principles for Vortex-Induced Vibrations

Vortex-Induced Vibrations (VIV) are cyclic motions in flexible slender structures that are induced by the shedding of vortices mostly transverse to the length of the structural member. The authors contend that the complete three-dimensional (3D) geometric changes that evolve in the structure are too often overlooked when investigating the basic physical nature of VIV. In this paper, we use a physics-based numerical model of a cable (a specific type of slender structure) to demonstrate the following mechanics principles: • Fluid drag (or other field loading) results in 3D geometric changes in a suspended cable. • Those changes necessarily include a lack of structural stiffness in the cable transverse to fluid flow. • In those instances, the structure will inevitably deflect to any kind of transverse action, particularly fluid vortices. • The nonlinear nature of this mechanism allows VIV to occur over a range of time periods, often called “lock-in.” Although the vortex shedding in the fluid provides the necessary repetitive inducement action, the evolving geometry of flexible slender structure appears to be the dominant factor concerning the actual nature (amplitude, pattern, etc.) of the resulting VIV behavior.

Resonance in herbaceous plant stems as a factor in vibrational communication of pentatomid bugs (Heteroptera: Pentatomidae)

Pentatomid bugs communicate using substrate-borne vibrational signals that are transmitted along herbaceous plant stems in the form of bending waves with a regular pattern of minimal and maximal amplitude values with distance. We tested the prediction that amplitude variation is caused by resonance, by measuring amplitude profiles of different vibrational pulses transmitted along the stem of a Cyperus alternifolius plant, and comparing their patterns with calculated spatial profiles of corresponding eigenfrequencies of a model system. The measured distance between nodes of the amplitude pattern for pulses with different frequencies matches the calculated values, confirming the prediction that resonance is indeed the cause of amplitude variation in the studied system. This confirmation is supported by the resonance profile obtained by a frequency sweep, which matches theoretical predictions of the eigenfrequencies of the studied system. Signal bandwidth influences the amount of amplitude variation. The effect of both parameters on signal propagation is discussed in the context of insect vibrational communication.

Synthesis of randomness in the radiated fields of antenna array

An alternative approach is based on statistically computed signal analysis technique for the design of antenna array exhibiting lower side lobes in their radiation pattern. New and generalized expressions for the array factor of all physically realizable linear antenna arrays are introduced. An algorithm based on the statistically computed signal analysis is designed. By considering the random elements, distance between the sensors, their mean, variance, average amplitude pattern and correlation of the amplitude between the two angles, some mathematical formulations have been done and shown with the help of MATLAB. Based on these generalized expressions, a new way of synthesizing arrays with reduced side lobes is available. It applies to end fire antenna array, which may have either even or odd numbers of sensors with restricted elements spacing. Final expressions shown are a clear relationship between elements excitation and null location in the radiation patterns.

Seismoelectric interface response: Experimental results and forward model

Understanding the seismoelectric interface response is important for developing seismoelectric field methods for oil exploration and environmental/engineering geophysics. The existing seismoelectric theory has never been validated systematically by controlled experiments. We have designed and developed an experimental setup in which acoustic-to- electromagnetic wave conversions at interfaces are measured. An acoustic source emits a pressure wave that impinges upon a porous sample. The reflected electric-wave potential is recorded by a wire electrode. We have also developed a full-waveform electrokinetic theoretical model based on the Sommerfeld approach and have compared it with measurements at positions perpendicular and parallel to the fluid/porous-medium interface. We performed experiments at several salinities. For 10-3 and 10-2 M sodium chloride (NaCl) solutions, both waveforms and amplitudes agree. For 10-4 M NaCl, however, amplitude deviations occur. We found that a single amplitude field scaling factor describes these discrepancies. We also checked the repeatability of experiments. The amplitudes are constant for the duration of an experiment (1–4 hours) but decrease on longer time scales [Formula: see text]. However, the waveforms and spatial amplitude pattern of the electric wavefield are preserved over time. Our results validate electrokinetic theory for the seismic-to-electromagnetic-wave conversion at interfaces for subsurface exploration purposes.

Durability Assessment of Quad Flat No-Lead Package Using Signal Analysis

This paper presents a methodology to determine the durability of Quad Flat No-Lead (QFN) package. The QFN package is useful for improving the reliability of the package. A mechanical fatigue test namely three points bending cyclic test and signal analysis were proposed in this paper. The three points bending cyclic test method is a test assembly that supports a specimen on two anvils or rollers, and symmetrically loads the specimen on the opposite surface with an anvil or roller using micro-tester machine. For strain signal collection, a strain gauge was connected to the dynamic data acquisition system, and it was used for each tested QFN package for determining the response of the captured cyclic strain signal. It was found that the sinusoidal amplitude pattern of signal response has been obtained during the constant three points bending cyclic test. The obtained response signals were then analysed using the Power Spectral Density.