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In order to solve the problem of poor inversion ability of multiple magnetic field sources inside small-scale objects, a multi-magnetic source inversion technology for small-scale objects was proposed. The atomic magnetometer was used to collect the magnetic source signal, the distribution of the magnetic source was inverted based on the theory of weak field, the distribution source model and Gauss-Seidel iterative algorithm were introduced to optimize the solution process, and the forward and inverse model was verified. At the same time, the point source model deconvolution operation was used to improve the spatial resolution of the magnetic source, and the spatial resolution of the system is about 10 mm before deconvolution and less than 4 mm after deconvolution. The results show that the spatial position distribution of the magnetic source inversion is roughly close to the real one, which verifies the correctness of the inversion technology and can be used for the identification of magnetic sources in precision instruments. This research has opened up a new way for the detection of multiple magnetic sources inside some precision instruments. [ABSTRACT FROM AUTHOR]

Klebsiella pneumoniae (Kp) is widely distributed in nature. Pathogenic Kp can cause a wide range of clinical infections, including respiratory infection, bloodstream infection, liver abscess, urinary system infection and so on. As a famous "plasmid collector", Kp can habor different types of plasmids in its genome. As a result, multidrug-resistant (MDR) strains continue to appear in recent years. Especially, the emergence of hypervirulent MDR (hv-MDR) Kp brings great challenges to clinical treatment. Therefore, the ability of Kp to obtain foreign genes, especially drug resistance and virulence-related genes, has attracted the attention of a large number of scholars. As the major acquired immune system in bacteria, the active clustered regularly interspaced palindromic repeats/CRISPR-associated proteins (CRISPR-Cas) system can effectively block the horizontal transfer of mobile elements into the genome of Kp, especially for transfer ability of conjugative plasmids. In recent years, it has been found that some conjugative plasmids carry anti-CRISPR (Acr) protein to inhibit the activity of the CRISPR-Cas system encoded by host bacteria, escape the host immune recognition, and then can effectively transfer between hosts. The sequenced Kp genome showed that the main types of CRISPR-Cas system in its genome were type I-E and subtype I-E*. Therefore, analysis of the relationship between the CRISPR-Cas distribution and transfer ability of plasmid in Kp and further exploration of the mechanism of Acr protein in regulating the activity of CRISPR-Cas, will provide clues and direction to the dynamics of its genome evolution. It will eventually provide clinical guidance for the prevention and control of hv-MDR Kp. [ABSTRACT FROM AUTHOR]

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