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Based on the ESPRIT-like and polynomial rooting methods, a high-performance and low computational cost localization algorithm for the mixed near-field sources (NFS) and far-field sources (FFS) is proposed using the uniform linear sensor array. First, we combine the steering vectors of the two subarrays to eliminate the range parameters and then yield a new steering vector, which only contains direction-ofarrival (DOA) information. Second, based on the ESPRIT-like and polynomial rooting methods, the DOAs of all NFSs and FFSs are obtained from the new steering vector. Third, with the DOA estimates, the range parameters are estimated depending on the polynomial rooting method again; and further according to the number of the closest to the unit circle roots, we can determine the number of sources at the same DOA direction. Finally, based on the size of the range parameters, the types (NFS or FFS) of sources can be confirmed. In addition, the proposed algorithm does not require the high-order statistics or any 1-or 2-D search and thus has low computational cost. Meanwhile, it makes full use of the array aperture and obtains outstanding estimation performance for both the DOA and range parameters. Moreover, the proposed algorithm avoids parameter match procedure. Numerical experiments show the performance of the proposed algorithm in this paper.

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Saccharomyces cerevisiae Pif1 (ScPif1) is known as an ATP-dependent DNA helicase that plays critical roles in a number of important biological processes such as DNA replication, telomere maintenance and genome stability maintenance. Besides its DNA helicase activity, ScPif1 is also known as a single-stranded DNA (ssDNA) translocase, while how ScPif1 translocates on ssDNA is unclear. Here, by measuring the translocation activity of individual ScPif1 molecules on ssDNA extended by mechanical force, we identified two distinct types of ssDNA translocation. In one type, ScPif1 moves along the ssDNA track with a rate of ∼140 nt/s in 100 μM ATP, whereas in the other type, ScPif1 is immobilized to a fixed location of ssDNA and generates ssDNA loops against force. Between the two, the mobile translocation is the major form at nanomolar ScPif1 concentrations although patrolling becomes more frequent at micromolar concentrations. Together, our results suggest that ScPif1 translocates on extended ssDNA in two distinct modes, primarily in a ‘mobile’ manner.

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