Multiwavelength fiber laser using S-band erbium-doped fiber amplifier and semiconductor optical amplifier

A multiwavelength fiber ring laser that is based on an S-band erbium-doped fiber amplifier (EDFA) and a semiconductor optical amplifier (SOA) is developed. An optical switch is used to switch the multiwavelength fiber laser between S-band and L-band. This fiber laser can stably lase seven wavelengths in the S-band or 28 wavelengths in the L-band. Additionally, the lasing wavelengths with a signal-to-noise ratio of over 33 dB and a wavelength spacing of 100 GHz are demonstrated experimentally. The average powers of the lasing wavelength in the S-band and the L-band are −7.53 and −12.15 dBm, respectively.     

Genotyping of intron 22 inversion of factor VIII gene for diagnosis of hemophilia A by inverse-shifting polymerase chain reaction and capillary electrophoresis

This is the first capillary electrophoresis (CE) analysis for diagnosis of hemophilia A (HA). The intron 22 inversion of factor VIII gene (F8) causes 40–50 % of severe bleeding disorder of HA in all human populations. Consequently, identification of the disease-causing mutations is becoming increasingly important for accurate genetic counseling and prenatal diagnosis. In this study, the key steps of inverse-shifting polymerase chain reaction (IS-PCR) and of short-end injection capillary electrophoresis were used for more specific and rapid genotyping of intron 22 inversion of F8. In IS-PCR, three specific primers were used to amplify 512-bp amplicon for wild type and 584-bp amplicon for patients with intron 22 inversion. The capillary gel electrophoresis (CGE) system was performed using 1× Tris–borate–EDTA (TBE) buffer containing 0.3 % (w/v) polyethylene oxide (PEO). The PCR amplicons were electrokinetically injected at 10 kV for 10 s at a temperature of 25 °C. The optimal short-end injection CGE was applied to detect the F8 gene of HA patients and carriers within 5 min. Intron 22 inversion was indeed found on some HA patients (13/35, 37.1 %). All genotyping results showed good agreement with DNA sequencing method and long-distance polymerase chain reaction (LD-PCR). The IS-PCR combined with short-end injection CGE method was feasible and efficient for intron 22 inversion screening of F8 in the HA populations.     

Excitation of accelerating wakefields in inhomogeneous plasmas

The excitation of the wakefields in an inhomogeneous plasma by a short laser pulse is investigated theoretically. A general equation for the wake excitation in transversely nonuniform plasma is derived. This equation is applied to the step-function density profile model of hollow channel laser wakefield accelerator. A more realistic model, in which the transition between the evacuated channel and the homogeneous surrounding plasma occurs over a finite radial extent, is then analyzed. It is shown that the excited channel made can interact resonantly with the plasma electrons inside the channel wall, leading to secular growth of the electric field. This eventually results in wavebreaking and the dissipation of the accelerating mode. We introduce an effective quality factor Q for the hollow channel laser wakefield geometry. This resonance limits the number of electron bunches that can be accelerated in the wake of single laser pulse     

Modeling particle deposition from fully developed turbulent flow

An unsteady state transfer of immersed particles within the interval between the arrival of eddies is solved by use of the Laplace transform schemes. The mean particle flux and the mean particle transport mechanisms are automatically considered on the average sublayer growth period by formulating the mean distributions as a stochastic process with the aid of exponentially distributed density function. The proposed relationship for the particle deposition velocity of average time domain obtained by this analysis is expressed as the form of analytical equation, with the inclusion of the effects of Brownian diffusion, turbulent eddy diffusivity, turbophoresis, and thermophoresis. The solution of this equation is in reasonable agreement with the measured deposition velocities for three distinct categories. This mathematical framework offers a simple computation tool of practical use to aerosol engineers and can further extend by including appropriate forces in the analytical formulation through the equilibrium among acceleration terms.     

Dynamical precession of spin in the two-dimensional spin-orbit coupled systems

We investigate the spin dynamics in the two-dimensional spin-orbit coupled system subject to an in-plane (x-y plane) constant electric field, which is assumed to be turned on at the moment $t=0$. The equation of spin precession in linear response to the switch-on of the electric field is derived in terms of Heisenberg's equation by the perturbation method up to the first order of the electric field. The dissipative effect, which is responsible for bringing the dynamical response to an asymptotic result, is phenomenologically implemented à la the Landau-Lifshitz-Gilbert equation by introducing damping terms upon the equation of spin dynamics. Mediated by the dissipative effect, the resulting spin dynamics asymptotes to a stationary state, where the spin and the momentum-dependent effective magnetic field are aligned again and have nonzero components in the out-of-plane (z) direction. In the linear response regime, the asymptotic response obtained by the dynamical treatment is in full agreement with the stationary response as calculated in the Kubo formula, which is a time-independent approach treating the applied electric field as completely time-independent. Our method provides a new perspective on the connection between the dynamical and stationary responses.     

Simultaneously optimizing link tolls and signal settings in a road network

The problem of determining link tolls to reduce traffic congestion is often referred as a toll design problem. In this paper, optimal tolls are determined for signal-controlled junctions in urban traffic road networks where the rerouting traffic is properly taken into account. This problem can be formulated as a mathematical program with equilibrium constraints (MPEC) where the user equilibrium is expressed as a variational inequality problem. Due to the non-differentiability of the equilibrium problem, an efficient convergent solution scheme is established. Numerical calculations are conducted on a variety of example road networks and comparisons are made with earlier methods.