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In this article, the intrinsic propagation mechanisms and dispersion properties of the dominant modes supported by different 2-D graphene-based transmission lines (GTLs) at terahertz (THz) are studied in detail. By employing a complete elliptic integral of the first kind, analytical expressions for the wavenumber of plasmons in different GTLs are obtained from the strongly coupled TM mode surface plasmons that propagate on each individual graphene stripline. Besides, per unit length equivalent circuits of different graphene coplanar transmission lines (GCTLs) are introduced. Again, analytical relations between their effective TM mode equivalent circuit lumped elements and graphene surface conductivity are investigated. Moreover, the effects of different GCTLs versus different parameters of the GCTL models for the wavenumber and circuit lumped elements are analyzed. The proposed analytical expressions could reveal the important mechanisms involved in spatially dispersive plasmon propagation connecting with the intrinsic properties of graphene. The features of GCTLs are detailed, showing their great potential for THz applications in future graphene-based nanoelectromagnetic and nanophotonic devices.

A technique of continuous shaping current waveform to suppress relaxation oscillations (ROs) of distributed feedback (DFB) laser for a high-performance optic system is demonstrated. To effectively suppress ROs, expressions for the shaping current waveform are theoretically derived based on the rate equations and different polynomials for the $3^{rd}$ , $5^{th}$ , and $8^{th}$ order Fourier basis functions are introduced. The convolutional neural network (CNN) is employed to predict the multi-parameter values that determine the results of the shaping input current, which exempt from the difficult and time-consuming process of parameter selection. Prior to training, preprocessing of the data obtained from DFB laser forward simulation using min-max normalization aims to improve the training efficiency of the CNN. The shaping current signals obtained from the CNN predicted parameters are put into the equivalent circuit model for the DFB laser to verify the effectiveness of the shaping current technique and CNN parameter optimization. Afterwards, the shaping current waveform is verified in a time division multiplex passive optical network (TDM-PON) utilizing the DFB laser model as a directly modulated source achieving remarkable performance with low cost. The results show that the high-order continuous shaping current modulated technique can successfully suppress the ROs and enhance the performance of the optic system.

Extrinsic BMP and LIF signaling collaboratively maintain mouse embryonic stem cell (ESC) pluripotency, whereas appropriate ERK activity is essential for ESC fate commitment. However, how the extrinsic signals restrain appropriate ERK activity remains elusive. Here, we show that, whereas LIF sustains relatively high ERK activity, BMP4 can steadily attenuate ERK activity by upregulating ERK-specific dual-specificity phosphatase 9 (DUSP9). This upregulation requires Smad1/5 and Smad4 and specifically occurs to DUSP9, but not other DUSPs, and only in ESCs. Through DUSP9-mediated inhibition of ERK activity, BMP signaling reinforces the self-renewal status of mouse ESCs together with LIF. Upon LIF withdrawal, ESCs spontaneously undergo neural differentiation, during which process DUSP9 can partially mediate BMP inhibition on neural commitment. Collectively, our findings identify DUSP9 as a critical mediator of BMP signaling to control appropriate ERK activity critical for ESC fate determination.