Parametrically controlling solitary wave dynamics in modified Kortweg-de Vries equation

We demonstrate the control of solitary wave dynamics of modified Kortweg-de Vries (MKdV) equation through the temporal variations of the distributed coefficients. This is explicated through exact cnoidal wave and localized soliton solutions of the MKdV equation with variable coefficients. The solitons can be accelerated and their propagation can be manipulated by suitable variations of the above parameters. In sharp contrast with nonlinear Schr\"{o}dinger equation, the soliton amplitude and widths are time independent.Comment: 4 pages, 5 eps figure

Prepare your mind for learning

The learning process must evolve and expand throughout one\u27s IT career. Most would agree that\u27s often easier said than done. Here are some ways professionals can overcome mental blocks that may prevent learning

Clarifying the Role of Self-Efficacy and Metacognition as Indicators of Learning: Construct Development and Test

We propose extending our understanding of self-efficacy by comparing self-efficacy with a related construct called metacognition. Metacognition involves the monitoring and control of one\u27s thought processes and is often related, as is self-efficacy, to performance on a task. We develop an instrument that attempts to measure both self-efficacy and metacognition with respect to one\u27s performance on a test covering declarative and procedural knowledge (knowing that, and knowing how) of DFDs and ERDs. With data collected from a sample of 124 students, we use partial least squares (PLS) to show that self-efficacy and metacognition are distinct yet related constructs. While self-efficacy is a predictor of both declarative and procedural knowledge, metacognition is only related to procedural knowledge. We discuss the implications of these results and suggest further research is needed to compare and contrast the role of these constructs in assessing learning outcomes

Comparing Self-Efficacy and Metacognition as Indicators of Performance

We report the results of a pilot study that compared the computer self-efficacy construct with metacognition. While self-efficacy is primarily affective and refers to one’s beliefs about one’s ability to perform a task, metacognition is primarily cognitive and refers to one’s thoughts about one’s ability to perform a task. Given their similarity, both have been used as surrogate measures of knowledge or skill. We developed an instrument to measure both constructs and applied the instrument to a set of MIS students taking an Analysis and Design course. Factor analysis produced a five-factor model, with metacognition factoring out as a unidimensional scale. Implications for further research are discussed

Template-free 13-protofilament microtubule–MAP assembly visualized at 8 A resolution

Microtubule-associated proteins (MAPs) are essential for regulating and organizing cellular microtubules (MTs). However, our mechanistic understanding of MAP function is limited by a lack of detailed structural information. Using cryo-electron microscopy and single particle algorithms, we solved the 8 Å structure of doublecortin (DCX)-stabilized MTs. Because of DCX’s unusual ability to specifically nucleate and stabilize 13-protofilament MTs, our reconstruction provides unprecedented insight into the structure of MTs with an in vivo architecture, and in the absence of a stabilizing drug. DCX specifically recognizes the corner of four tubulin dimers, a binding mode ideally suited to stabilizing both lateral and longitudinal lattice contacts. A striking consequence of this is that DCX does not bind the MT seam. DCX binding on the MT surface indirectly stabilizes conserved tubulin–tubulin lateral contacts in the MT lumen, operating independently of the nucleotide bound to tubulin. DCX’s exquisite binding selectivity uncovers important insights into regulation of cellular MTs

S-, P- and D-wave resonances in positronium-sodium and positronium-potassium scattering

Scattering of positronium (Ps) by sodium and potassium atoms has been investigated employing a three-Ps-state coupled-channel model with Ps(1s,2s,2p) states using a time-reversal-symmetric regularized electron-exchange model potential fitted to reproduce accurate theoretical results for PsNa and PsK binding energies. We find a narrow S-wave singlet resonance at 4.58 eV of width 0.002 eV in the Ps-Na system and at 4.77 eV of width 0.003 eV in the Ps-K system. Singlet P-wave resonances in both systems are found at 5.07 eV of width 0.3 eV. Singlet D-wave structures are found at 5.3 eV in both systems. We also report results for elastic and Ps-excitation cross sections for Ps scattering by Na and K.Comment: 9 pages, 5 figures, Accepted in Journal of Physics

Pedestal free pulse compression of chirped optical solitons

Peer reviewedPostprin

Controlling pulse propagation in optical fibers through nonlinearity and dispersion management

In case of the nonlinear Schr\"odinger equation with designed group velocity dispersion, variable nonlinearity and gain/loss; we analytically demonstrate the phenomenon of chirp reversal crucial for pulse reproduction. Two different scenarios are exhibited, where the pulses experience identical dispersion profiles, but show entirely different propagation behavior. Exact expressions for dynamical quasi-solitons and soliton bound-states relevant for fiber communication are also exhibited.Comment: 4 pages, 5 eps figure