State-related electroencephalographic deviances in attention deficit hyperactivity disorder

The dynamic security region (DSR) of bulk power system has been accepted more and more in recent years for providing plenty of security information and good prospect in online application. This paper compares three linear approximations for the dynamic security region of network-reduction power systems. The three linear approximations are the Q-linear approximation based on the quadratic approximation of stability region, the L-linear approximation based on the linear approximation of stability region and the L0-linear approximation based on the invariant assumption of the normal vector for the boundary of the stability region corresponding to different control variable. The three linear approximations are all obtained with a same critical point lying just on the boundary of dynamic security region. The critical point is searched with numerical simulation. The accuracy of the three linear approximations is compared, using the linear approximation obtained with the curve fitting approach or the actual boundary of DSR searched as the benchmark. Simulation results in IEEE 3-machine 9-bus system and 10-machine 39-bus New England system show that all the three linear approximations display fairly accurate estimation. Furthermore, from the computational viewpoint, the L-linear and the L0-linear method are two alternative choices to approximate the dynamic security region.link_to_subscribed_fulltex

Generation of widely tunable picosecond pulses with large SMSR by externally injecting a gain-switched dual laser source

The authors demonstrate a procedure of generating picosecond optical pulses that are tunable over a wide wavelength range (65 nm) and have very high spectral purity side-mode suppression ratio [(SMSR)>60 dB]. The large tuning range is obtained by employing external injection into a gain-switched source containing two Fabry-Pe/spl acute/rot lasers. The use of a widely tunable Bragg grating at the output improves the SMSR such that it exceeds 60 dB over the entire tuning range

The importance of understanding computer analyses in civil engineering

Sophisticated computer modelling systems are widely used in civil engineering analysis. This paper takes examples from structural engineering, environmental engineering, flood management and geotechnical engineering to illustrate the need for civil engineers to be competent in the use of computer tools. An understanding of a model's scientific basis, appropriateness, numerical limitations, validation, verification and propagation of uncertainty is required before applying its results. A review of education and training is also suggested to ensure engineers are competent at using computer modelling systems, particularly in the context of risk management. 1. Introductio

Numerical analysis of pulse pedestal and dynamic chirp formation on picosecond modelocked laser pulses after propagation through a semiconductor optical amplifier

A numerical analysis, based on a modified Schrodinger equation, of the formation of pulse pedestals and dynamic chirp formation on picosecond pulses after propagation through a semiconductor optical amplifier is presented. The numerical predictions are confirmed by an experiment that utilises the frequency resolved optical gating technique for the amplified pulse characterisation

Experimental investigation of the impact of optical injection on vital parameters of a gain-switched pulse source

An analysis of optical injection on a gain-switched distributed feedback (DFB) laser and its impact on pulse parameters that influence the performance of the pulse source in high-speed optical communication systems is presented in this paper. A range of 10 GHz in detuning and 5 dB in injected power has been experimentally identified to attain pulses, from an optically injected gain-switched DFB laser, with durations below 10 ps and pedestal suppression higher than 35 dB. These pulse features are associated with a side mode suppression ratio of about 30 dB and a timing jitter of less than 1 ps. This demonstrates the feasibility of using optical injection in conjunction with appropriate pulse compression schemes for developing an optimized and cost-efficient pulse source, based on a gain-switched DFB laser, for high-speed photonic systems

Oscillatory dynamics of perceptual to conceptual transformations in the ventral visual pathway

Object recognition requires dynamic transformations of low-level visual inputs to complex semantic representations. While this process depends on the ventral visual pathway (VVP), we lack an incremental account from low-level inputs to semantic representations, and the mechanistic details of these dynamics. Here we combine computational models of vision with semantics, and test the output of the incremental model against patterns of neural oscillations recorded with MEG in humans. Representational Similarity Analysis showed visual information was represented in alpha activity throughout the VVP, and semantic information was represented in theta activity. Furthermore, informational connectivity showed visual information travels through feedforward connections, while visual information is transformed into semantic representations through feedforward and feedback activity, centered on the anterior temporal lobe. Our research highlights that the complex transformations between visual and semantic information is driven by feedforward and recurrent dynamics resulting in object-specific semantics

80 Gb/s optimised pulse source using a gain-switched laser diode in conjunction with a nonlinearly chirped grating

The authors demonstrate the generation of transforms limited short optical pulses, which display excellent spectral and temporal qualities by employing a novel technology, based on an externally injected gain-switched laser in conjunction with a non-linearly chirped grating. Using this technique, 3.5 ps optical pulses, exhibiting a time bandwidth product of 0.45, are generated, which are suitable for use in high-speed 80 Gb/s OTDM communications systems

System-performance analysis of optimized gain-switched pulse source employed in 40-and 80-Gb/s OTDM systems

The development of ultrashort optical pulse sources, exhibiting excellent temporal and spectral profiles, will play a crucial role in the performance of future optical time division multiplexed (OTDM) systems. In this paper, we demonstrate the difference in performance in 40- and 80-Gb/s OTDM systems between optical pulse sources based on a gain-switched laser whose pulses are compressed by a nonlinearly and linearly chirped fiber Bragg grating. The results achieved show that nonlinear chirp in the wings of the pulse leads to temporal pedestals formed on either side of the pulse when using the linearly chirped grating, whereas with the nonlinearly chirped grating, pedestals are essentially eliminated. In an OTDM system, these pedestals cause coherent interaction between neighboring channels, resulting in intensity fluctuations that lead to a power penalty of 1.5 dB (40 Gb/s) and 3.5 dB (80 Gb/s) in comparison to the case where the nonlinearly chirped grating is used. Simulations carried out with the aid of Virtual Photonics Inc. verify the results achieved

Isolation of a Housefly Head Protein Fraction that Exhibits High Affinity Binding of Cholinergic Ligands

The purification is described of a protein fraction, isolated from the central nervous system of housefly heads, that exhibits high affinity for cholinergic ligands. The purified material was found tq bind with high affinity acetylcholine, nicotinic ligands such as nicotine and decamethonium as well as atropine, dexetimide a:qg pilocarpine which are of a muscarinic nature. With all the ligands there appeared to be only a single site for binding with measured dissociation constants varying from 6.2 X 10-s M (dexetimide) to 5.4 x 10-6 M (pilocarpine). The concentration of binding sites was in the range of 381 nmol g-1 of protein (atropine) to 560 nmol g-1 of protein (pilocarpine)

Pulse source for 80 Gb/s systems using a gain-wwitched laser diode followed by a nonlinearly chirped grating

This work presents the generation of 3.5 ps pulses at a repetition rate of 10 GHz and the optimization of the pulse spectrum. The output pulses are near transform limited and have pulse pedestals that are virtually eliminated to 35 dB down from the peak of the pulse, thus providing a source suitable for use in 80 Gb/s OTDM systems