Statistical Analysis for Collision-free Boson Sampling.

Boson sampling is strongly believed to be intractable for classical computers but solvable with photons in linear optics, which raises widespread concern as a rapid way to demonstrate the quantum supremacy. However, due to its solution is mathematically unverifiable, how to certify the experimental results becomes a major difficulty in the boson sampling experiment. Here, we develop a statistical analysis scheme to experimentally certify the collision-free boson sampling. Numerical simulations are performed to show the feasibility and practicability of our scheme, and the effects of realistic experimental conditions are also considered, demonstrating that our proposed scheme is experimentally friendly. Moreover, our broad approach is expected to be generally applied to investigate multi-particle coherent dynamics beyond the boson sampling.

[Study on distribution of neural stem cells in the brain of Alzheimer disease transgenic mice through caudal vein transplantation].

OBJECTIVE: To observe whether neural stem cells (NSCs) can successfully permeate into the brain through the blood-brain barrier (BBB) of Alzheimer disease (AD) transgenic mice and explore the methods of distribution and migration. METHODS: NSCs were isolated from 12-day-old fetal mice, cultured, labeled with enhanced green fluorescent protein (eGFP) and then transplanted into 10 AD transgenic mice and normal mice as controls through caudal vein. The mice were killed 48 h, 1 w, 2 w, and 4 w after transplantation respectively. The brains of the mice were made into continual frozen sections, the distribution and migration of the eGFP-labeled NSCs were studied under fluorescence microscope. RESULTS: At different time points after transplantation the eGFP-labeled NSCs were diffusely distributed in the brain: distributed around the blood vessels in the first 48 h, and then migrated gradually towards the hippocampus and cortex until 4 weeks later. There were no obvious abnormal complications occurring after transplantation. CONCLUSION: NSCs can successfully permeate into the brain through the BBB of AD transgenic mice, and migrate into the brain parenchyma gradually.

Regionspecific survival and differentiation of mouse embryonic stem cell-derived implants in the adult rat brain.

Totipotent and regionally non-specified embryonic stem (ES) cells provide a powerful tool to understand mechanisms controlling stem cell differentiation in different regions of the adult brain. As the development capacity of ES cells in the adult brain is still largely unknown, we grafted small amounts of mouse ES (mES) cells into adult rat brains to explore the survival and differentiation of implanted mES cells in different rat brain regions. We transplanted the green fluorescent protein (GFP)-positive mES cells into the hippocampus, septal area, cortex and caudate nucleus in rat brains. Then the rats were sacrificed 5, 14 and 28 d later. Of all the brain regions, the survival rate of the transplanted cells and their progeny were the highest in the hippocampus and the lowest in the septal area (P<0.01). The grafted ES cells could differentiate into nestin-positive neural stem cells. Nestin-positive/GFP-positive cells were observed in all brain regions with the highest frequency of nestin-positive cells in the hippocampus and the lowest in the medial septal area (P<0.01). mES cells differentiated into end cells such as neurons and glial cells in all transplantation sites in recipient brains. In the hippocampus, the ES cells differentiated into neurons in large amounts. These results demonstrate that only some brain regions permit survival of mES cells and their progeny, and form instructive environments for neuronal differentiation of mES cells. Thus, because of region specific presence of microenvironmental cues and their environmental fields, the characteristics of the recipient tissue were considerably important in formulating cell replacement strategies for neural disorders.