Liu Song-hao

Dissociated brain organization for two-digit addition and subtraction: An fMRI investigation

The present study compared the patterns of brain activation elicited by two-digit addition and subtraction problems. Thirty-two Chinese undergraduates of the same educational background and of similar age were asked to assess whether arithmetic operations were true or false during functional magnetic resonance imaging. Results showed that both complex addition and subtraction were supported by the broad neural system that involved regions within the inferior parietal lobule, the precuneus, and the inferior occipital gyrus, as well as some subcortical structures. Nevertheless, complex problems involving addition elicited more activation mainly in the bilateral medial frontal gyrus, whereas problems involving subtraction had more activation in the precentral gyrus and the thalamus in the right hemisphere, as well as the inferior parietal lobule in the left hemisphere. This pattern of dissociated activation suggests that partially separate neuronal networks might support these different operations. It also suggests that complex addition has a greater reliance on the fronto-parietal cortical circuit and subtraction on the parieto-subcortical circuit.

Quantum Key Distribution System with Six Polarization States Encoded by Phase Modulation

An intrinsically stable quantum key distribution system (QKD) with six polarization states encoded by phase modulation is introduced. The encoder and decoder are in the same structures that consist of two polarizing Sagnac interferometers connected in tandem. The six polarization states are determined and distinguished by different sets of phase shifts induced by two respective electrically-driven integrated phase modulators. A mean visibility of interference fringes is kept stable at 97.58% for an hours performance. Theoretical and experimental analyses show that the proposed QKD system features intrinsically stability immune from environment fluctuation.

Propagation Control of Soliton Trains in Dispersion-Shifted Fibres in the Presence of Third-Order Dispersion

The evolution of soliton trains in dispersion-shifted fibres (DSFs) in the presence of third-order dispersion (TOD) is investigated. The results show that the collision of neighbouring solitons in the trains can be suppressed by means of a proper TOD, but the maximum transmission distance (or bandwidth) is limited by the increasing soliton separation that results from the TOD. It is also shown that the separation can be suppressed by adjusting the initial phase or amplitude difference between the solitons. These results are helpful to re-establish the potential application of the soliton-based optical-communication systems in DSFs.

THE RAMAN SCATTERING OF CARBON NANOTUBES PRODUCED IN DIFFERENT INERT GASES AND THEIR PRESSURES BY ARC DISCHARGE

First- and second-order Raman spectra of carbon nanotubes produced in helium and argon atmospheres at a pressure ranging from 11 to 92 kPa by arc discharge have been measured and compared with each other. The position and bandwidth of the spectral lines depend on the kind of inert gases and their pressure. The Raman spectra of the nanotubes produced in argon gas atmosphere are much more similar to that of polycrystalline graphite than those of the nanotubes produced in helium gas atmosphere. The position and bandwidth of nanotube Raman peaks change with gas pressure in arc discharge because different diameter distribution of nanotubes is produced at different inert gas pressure. The Raman spectra of nanotubes produced at high pressure is much more like that of graphite than those produced in lower pressure.

Experimental Study on Dual Wavelength and Dual Pulse Q-Switched Frequency Doubling on a Tunable Cr:LiSAF Laser

A flashlamp-pumped Cr:LiSAF laser system with a voltage controlled Q-switch structure in the cavity is designed. A dual-wavelength and dual-pulse tunable laser output is gained. The relation of laser output behavior with input energy is studied experimentally. The output is dual-pulsed with the energy of the 32 mJ/pulse producing the total output energy of 64 mJ and the pulse width is about 27 ns at 850 nm. Then, we use one LBO crystal as the frequency doubling crystal to obtain a dual wavelength (448.1 nm and 449.15 nm) and dual pulse laser. The output for one wavelength is about 10.3 mJ and the line width is less than 0.02 nm.

Compression of Soliton Pairs in Dispersion-Decreasing Fibres

The compression of soliton pairs in fibres with decreasing dispersion is studied. The results show that generation of high-quality stable pedestal-free pulses is strongly affected by the interaction between soliton pairs. The initial phase difference between two solitons can modify soliton interaction and can make the neighbouring solitons never collide periodically. The soliton pairs can be compressed selectively so that one of the two solitons can achieve enhanced compression by controlling the initial phase difference.

Method to detect the variants of the erythrocyte in a rat model of Aβ25-35-induced neurotoxicity based on micro-Raman spectroscopy.

Abstract. Alzheimer’s disease irreversibly and progressively damages the brain, but the treatments in clinical trials are too slow. So, we hypothesized that the presence of erythrocyte variants with AD could be used as a noninvasive means to predict or trigger for administration of the preventive therapeutics, and the aim of this study is to develop a method using Raman spectroscopy in a rat model of Aβ25−35-induced neurotoxicity, and then evaluate the protective effect of bajijiasu by this method. Results showed that the Raman spectra fingerprints of the erythrocyte of model group were obvious different from those of the normal control, as peaks around the region 650  cm−1 belonged to the s–s makers, 1605  cm−1 corresponded to the high spin (deoxygenated-Hb) marker, 1374  cm−1 arises from ν4 as a sign of concentration of O2, and 1123 and 1033  cm−1 are associated with the trans stretching vibrations of CAC skeleton. Results also showed that bajijiasu can make these changes recover. Our study also suggested that erythrocyte variants detected using Raman spectroscopy should be tested in a specific longitudinal study for the association with AD diagnosis, and if positive, can be used as a prognostic marker.

Simple Algorithm for Deterministic Entanglement Concentration

We first present the general solution and the simplest special solution of the doubly stochastic matrix used in deterministic entanglement concentration. Then, we give a better scheme to realize deterministic entanglement concentration. Under this scheme, the concentration is realized, and more importantly, two partially entangled pairs concentrate to four-particle Greenberger–Horne–Zeilinger (GHZ) states with a certain probability.

Enhanced pulse compression induced by the interaction between the third-order dispersion and the cross-phase modulation in birefringent fibres

In this paper, we report on the enhanced pulse compression due to the interaction between the positive third-order dispersion (TOD) and the nonlinear effect (cross-phase modulation effect) in birefringent fibres. Polarization soliton compression along the slow axis can be enhanced in a birefringent fibre with positive third-order dispersion, while the polarization soliton compression along the fast axis can be enhanced in the fibre with negative third-order dispersion. Moreover, there is an optimal third-order dispersion parameter for obtaining the optimal pulse compression. Redshifted initial chirp is helpful to the pulse compression, while blueshifted chirp is detrimental to the pulse compression. There is also an optimal chirp parameter to reach maximum pulse compression. The optimal pulse compression for TOD parameters under different N-order solitons is also found.

Numerical Study of the Apodization Profile Functions, Optimal Profiles and Lengths of a Linearly Chirped Fibre Bragg Grating

Starting from our definition of apodization profile functions, we discover the optimal profiles and the characteristics of defined apodization functions in sidelobe suppression. It is shown by numerical analysis that the optimal grating length is 45?mm to compensate for dispersion induced by 100?km fibres and the smoothness of the ripples in time-delay characteristics is related to the defined parameters.