中枢多巴胺系统正电子发射计算机断层扫描显像剂的研究进展

中枢多巴胺系统与多种神经行为障碍的病理生理学有关。一直以来,多巴胺系统正电子发射计算机断层扫描(PET)成像在研究活体大脑中多巴胺生物化学过程上有着重要价值。PET成像的基础是¹¹C、¹⁸F等发射正电子的放射性核素标记的显像剂,这些显像剂通过与多巴胺神经系统不同的靶点特异性结合从而反映多巴胺合成、囊泡储存、突触释放和受体结合以及再摄取过程,推动神经病学、精神病学、药物滥用和成瘾以及药物开发的研究进展。本文综述了以氨基酸脱羧酶、多巴胺转运体、多巴胺受体以及囊泡单胺转运体为靶点的¹¹C、¹⁸F标记的PET显像剂的研究进展。     

On convexity of a planar domain with a pair of concave tomography projections

We describe simple sufficient conditions on tomography-type measurements of a planar set which imply convexity of this set. The cases of partial convexity and higher-dimensional sets are considered as well.     

Phase calculation with a swept source in optical coherence tomography: Jitter influence

An analysis of phase modifications introduced by laser jitter in frequency-domain optical coherence tomography (OCT) is described. It is shown that a 1D spurious phase function is introduced as a consequence of this phenomenon. This phase function is added to any other introduced by the object under analysis causing a superposition of both. The result may impose some limitations for unambiguous determination of phase changes of objects. Experimental and theoretical results are presented.     

A note on medieval microfabrication: the visualization of a prayer nut by synchrotron‐based computer X‐ray tomography

One of the most fascinating objects in the Rijksmuseum (Amsterdam, The Netherlands) is an early 16th century prayer nut. This spherical wooden object measures 4 cm in diameter and consists of two hemispheres connected with a small hinge so that it can be opened. The interior of the nut holds wood carvings with scenes from the life of Christ. These miniature reliefs show an incredible degree of finish with carving details well beyond the millimetre scale. In the present paper it is shown how synchrotron‐based computer X‐ray tomography revealed the structure and fabrication method of the bead. The central part of the relief was cut from a single piece of wood, rather than assembled from multiple components, underlining the extraordinary manual dexterity of its maker. In addition, a piece of fibrous material contained in the inner structure of the bead is revealed. This may have served as a carrier for an odorous compound, which would be in line with the religious function of the prayer nut.     

Product measurements and fully symmetric measurements in qubit-pair tomography: A numerical study

State tomography on qubit pairs is routinely carried out by measuring the two qubits separately, while one expects a higher efficiency from tomography with highly symmetric joint measurements of both qubits. Our numerical study of simulated experiments does not support such expectations.     

Parallel Schwarz alternating methods for anisotropic diffusion of speckled medical images

This paper deals with ultrasound medical image processing, particularly to filter the noise while preserving the edges and structures of information. The mathematical processing consists in solving by a numerical way a nonlinear evolutive boundary value problem. Several numerical semi-implicit time marching schemes are considered and analyzed. At each time step, parallel synchronous or asynchronous Schwarz alternating methods are used to solve the linear system and its convergence is studied. Lastly, the results of sequential and parallel simulations are presented.      

聚多巴胺包覆的金纳米棒用于大鼠下颌下腺造影成像

用生物相容性好且毒性低的聚多巴胺对金纳米棒进行表面包覆, 利用其造影增强的功能, 将聚多巴胺包覆的金纳米棒应用于大鼠下颌下腺导管, 实现了下颌下腺造影成像.     

Experimentally Determining Bloch Parameters of Hamiltonian for Single-Qubit Systems

By considering the identification problem of unknown but fixed Hamiltonian H = S0σ0 ＋∑i=x,y,z Siσi where σi （i = x, y, z） are pauli matrices and σ0=I, we explore the feasibility and limitation of empirically determining the Hamiltonian parameters for quantum systems under experimental conditions imposed by projective measurements and initialization procedures. It may be unsurprising to physicists that one can not obtain the knowledge of So no matter what kind of projective measurements and initialization are permitted, but the observation draws our attention to the importance of the parameter identifiability under different experimental condition. It has also been revealed that one can obtain the knowledge of ｜Sz｜ and Sx^2＋Sy^2 at most when only the projective measurement {｜0/（0｜, ｜1/（1｜} is permitted to perform on and initialize the qubit. Further more, we demonstrated that it is feasible to distinguish ｜Sx｜, ｜Sy｜, and ｜Sz｜ even without any a priori information about Hamiltonian if at least two kinds of projective measurement or initialization procedures are permitted. It should be emphasized that both projective measurements and initialization procedures play an important role in quantum system identification.     

Acoustic dipole radiation model for magnetoacoustic tomography with magnetic induction

An acoustic dipole radiation model for magnetoacoustic tomography with magnetic induction (MAT-MI) is pro-posed,based on the analyses of one-dimensional tissue vibration,three-dimensional acoustic dipole radiation and acoustic waveform detection with a planar piston transducer.The collected waveforms provide information about the conductiv-ity boundaries in various vibration intensities and phases due to the acoustic dipole radiation pattern.Combined with the simplified back projection algorithm,the conductivity configuration of the measured layer in terms of shape and size can be reconstructed with obvious border stripes.The numerical simulation is performed for a two-layer cylindrical phantom model and it is also verified by the experimental results of MAT-MI for a tissue-like sample phantom.The proposed model suggests a potential application of conductivity differentiation and provides a universal basis for the further study of conductivity reconstruction for MAT-MI.