External modulation method for generating accurate linear optical FMCW

Frequency modulation continuous wave (FMCW) lasers are key components in modern optical imaging. However, current intracavity modulation lasers do not exhibit low-frequency jitter rate and high linearity due to the inherent relaxation oscillations. Although this may be compensated in a direct modulation laser diode using an optoelectronic feedback loop, the available sweep speed is moderately small. In this letter, a special external modulation method is developed to improve the performance of FMCW. Since only the first sideband optical field is used during the entire generation process, phase noise is kept to a minimum and is also independent of the sweep speed. We demonstrate that the linearity and jitter rates do not deteriorate appreciably when the sweep speed is changed over three orders of magnitude, even up to the highest sweep speed of 2.5 GHz/ μs

Revisiting the volatility of gold : Is gold a hedge or a safe haven?

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Simultaneous Change-point Detection and Curve Estimation for Single and Multiple Sequential Data

In this dissertation, I propose a new class of nonparametric regression methods that account for discontinuities in single and multiple sequential data. The new method is called Simultaneous CHange-point detection And Curve Estimation (SCHACE), which can automatically detect jumps in data sequences and, at the same time, accurately capture nonlinear trends between these jumps in the mean curve. The SCHACE is a unified regularization framework that nicely integrates two statistical tools: the normalized fused LASSO for change-point detection and B-splines for curve estimation. Notably, this approach is a single-step method that does not require iteration and is therefore computationally efficient and fast to implement. To evaluate the performance of SCHACE, I conduct extensive numerical experiments, including both simulated and real-world data examples, to demonstrate its advantages over other competing methods in the literature. Furthermore, I also study the problem of change-point detection for multiple data sequences simultaneously. Towards this, I propose two variants to generalize SCHACE by integrating group LASSO for change-point detection in multiple sequences and B-splines for nonparametric regression curve estimation. The first variant is a direct extension of SCHACE for multiple sequences, which selects the degrees of freedom for B-splines by a grid-based tuning procedure. This method assumes the same level of smoothness shared by the mean of multiple sequences. To relax this assumption, I propose the second variant, which allows for different levels of smoothness across multiple curves. It first assigns relatively high degrees of freedom to B-splines for each sequence and then imposes a penalty to coefficients of the B-spline basis matrix. In this way, the degrees of freedom of B-splines for each sequence can be selected independently by solving an optimization problem

Human Capital Spillovers from Special Economic Zones: Evidence from Yangtze Delta in China

This paper evaluates the effects of a place-based program in the Yangtze Delta of China—Special Economic Zones (SEZs). Taking into account spatial proximity, this paper quantifies the spillover effects of the human capital in SEZs. One major finding is that regional productivity benefits from the human capital in SEZs. The spillover effects are not only confined to their own counties, but also neighboring counties. SEZs contribute more to the regional productivity of neighboring counties than the one of the hosting county itself. Moreover, positive spillover effects of the human capital in SEZs still hold for the growth of regional productivity

G12R mutation in Cx26 downregulates the expression levels of TLR2 and its downstream inflammatory factors in keratinocytes

Objective To investigate the effect of G12R mutation in Cx26 on the expression of TLR2 and its downstream inflammatory factors in human keratinocytes. Methods Human keratinocytes (HaCaT) without (WT-Cx26) or with G12R-mutation (G12R-Cx26) were co-cultured with Trichophyton rubrum. Expression levels of TLR2 mRNA and its downstream effector molecules were detected by real-time PCR. The expression levels of TLR2 protein were detected by western blot. Cytokine levels in the culture medium were measured by ELISA. Immunofluorescence was used to determine distribution of Cx26 and TLR2 in G12R-Cx26 HaCaT cells. Results Expression levels of TLR2 mRNA were comparable between WT-Cx26 and G12R-Cx26 cells (t=1.92, P=0.190). However, G12R mutation in Cx26 decreased expression levels of TLR2 protein in cell membrane and cytoplasm (both P<0.01 vs. WT-Cx26) in addition to reductions in expression levels of downstream of TLR2 pathway, including TNF (t=6.91, P<0.05), IL-6 (t=13.03, P<0.01) and antimicrobial peptide LL-37 (t=25.31, P<0.001). Coculture of G12R-Cx26 cells with ikarugamycin increased co-localization of Cx26 and TLR2 on the cell membrane. Conclusion Cx26-G12R mutation down-regulates the expression of TLR2 and downstream inflammatory cytokines, including TNF, IL-6 and antimicrobial peptide LL-37, in keratinocytes

Perceptually realistic flower generation

This paper describes a method for generating flower growth animation in which a petal surface and shape can be changed in real time. Most plant modelling currently animates the plant development process by assuming a time interval and the corresponding growth direction, and cannot easily change the time step or deform the shape. In the model presented here we use a graphical representation for plant growth function, along with a new description of plant growth rate, to enable the user to obtain flexible parameters for surface control. The model generates non-deterministic results which give more realistic and varied petals than can be obtained using pre-defined surfaces or interpolating between given initial and final shapes