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The most significant assumption of conventional analytical methods (e.g., the subdomain technique) is that the stator and rotor iron cores are infinitely permeable. The magnetic saturation is ignored, resulting in an overestimation of the flux density. This article presents an analytical model of permanent magnet (PM) machines with segmented Halbach arrays (PMMSHA). It considers the finite magnetic permeabilities of the stator teeth and tooth tips (STTT) and can study the tooth saturation effect. The permeability variation in the slots and teeth is solved via Cauchy’s product theorem. Based on magnetic vector potential and the Maxwell–Fourier method, Poisson’s and Laplace’s equations in the stator teeth/slots, tooth tips/slot openings, air gap, and PMs regions are solved. Consequently, the electromagnetic performance, including the magnetic field distribution in all regions, exciting force density, cogging torque, and electromagnetic torque, is calculated. The results of finite element analysis (FEA) show that the analytical model is highly accurate. Furthermore, the influences of the permeability of the STTT and the number of blocks per pole (NBPP) on the performance of the PMMSHA are studied.

By using a database of 4,634 cold patches (high density and low electron temperature) and 4,700 hot patches (high density and high electron temperature) from Defense Meteorological Satellite Program F16 in 2005–2018 winter months (October–March), we present a statistical survey of the distributions of polar cap patches for different interplanetary magnetic field (IMF) orientations and ionospheric convection geometries. We investigate the dependence of cold and hot patches on local plasma transport and soft-electron precipitation. Our results indicate that: in winter, (a) more cold and hot patches occur in the stronger anti-sunward flow organized by different IMF orientations. (b) cold patches are frequent near the central polar cap, while hot patches are closer to the auroral oval. (c) enhanced anti-sunward flow (E × B drift) mainly contributes to cold patch occurrence under Bz < 0, and soft-electron precipitation contributes to hot patch occurrence both under southward and northward IMF. publishedVersion

The cycle frequencies of a cyclostationary signal can be used for the signal identification and classification, separation of the overlapped signals in cycle domain, and so on. Efficient cycle frequency acquisition depends on the fast measurement of cyclic autocorrelation function (CAF) or spectral correlation function (SCF) of the signal. Presently the relative efficient CAF and SCF measuring methods mainly include the cyclic correlogram, the well-known fast Fourier transform accumulation method (FAM), and so on. Motivated by these methods, a new efficient cycle frequency acquisition method which integrates the fast Fourier transform (FFT) algorithm with the autocorrelated cyclic autocorrelation function, named FACA, is presented. With the presented method, we can acquire the cycle frequencies of a cyclostationary signal more efficiently with a given level of reliability. Meanwhile, by enlarging the FFT window width of the FACA method we can get the same cycle frequency resolution as the benchmarked method FAM, but the computation cost still can be spared at this case.

In this work, the effect of uniaxial stress on the stability of magnetic skyrmion is studied by use of Monte Carlo simulations. The classical Heisenberg model with anisotropic exchanges and Dzyaloshinskii-Moriya interactions is applied to correlate the stress behavior. We calculate magnetization M and skyrmion number Q to estimate the phase transition points, use the spin configurations and their Fourier transform to determine the region of skyrmion state. The h − T phase diagram show the area of skyrmion state is larger with stress than without stress. These results are interpreted qualitatively by the energy competitions between Zeeman, exchanges and Dzyaloshinskii-Moriya interactions. The simulated results suggest that anisotropy induced by uniaxial stress can stabilize the skyrmion phase.

Ground-based observations can be used to provide substantial support for Cluster/Double Star measurements and greatly enhance the mission's scientific return. There are six Chinese ground stations involved in coordinated cluster/Double Star and ground-based instrument observations. Among them, the Chinese Zhongshan Station in Antarctica and the Yellow River Station on Svalbard are closely magnetic conjugate and are situated under the ionospheric projection of the magnetospheric cusp regions, which, combined with satellite data, provide a perfect configuration to conduct conjugate studies of cusp phenomena. In this paper we present the ground-based instrumentation at these stations, discuss the restriction which is applyed to the optical sites and present an overview of the occurrences for conjunctions of these instruments with the spacecraft. Samples of data products are given to illustrate the potential use of these instrumentations in coordination with Cluster/Double Star measurements.

Excessive greater splanchnic nerve (GSN) activation contributes to the progression of gastric ischemia-reperfusion (GI-R) injury. This study was designed to investigate the protective mechanism of cerebellar fastigial nucleus (FN) stimulation against GI-R injury.The GI-R injury model was induced in rats by clamping the celiac artery for 30 min, and then reperfusion for 30 min, 1, 3, 6, or 24 h, respectively.Microinjection of L-Glu (3, 6, 12 μg) into the FN dose-dependently attenuated GI-R injury and GSN activity. In addition, there was an enhancement of gastric mucosal blood flow in GI-R rats. Pretreatment with the glutamic acid decarboxylase antagonist into the FN, the GABAA receptor antagonist into the lateral hypothalamic area or lesion of superior cerebellar peduncle all reversed the protective effects of the FN stimulation. Furthermore, the FN stimulation reduced the TUNEL-positive gastric mucosal cell and Bax-positive gastric mucosal cell in GI-R rats.These results indicate that the protective effects of the FN stimulation against GI-R injury may be mediated by attenuation of the excessive GSN activation, gastric mucosal cell apoptosis, and Bax expression in GI-R rats.

We report a systematic study on the structural and electronic properties of Bi2Te3−xSex topological insulator alloy grown by molecular beam epitaxy (MBE). A mixing ratio of Bi2Se3 to Bi2Te3 was controlled by varying the Bi:Te:Se flux ratio. X-ray diffraction and Raman spectroscopy measurements indicate the high crystalline quality for the as-grown Bi2Te3−xSex films. Substitution of Te by Se is also revealed from both analyses. The surfaces of the films exhibit terrace-like quintuple layers and their size of the characteristic triangular terraces decreases monotonically with increasing Se content. However, the triangular terrace structure gradually recovers as the Se content further increases. Most importantly, the angle-resolved photoemission spectroscopy results provide evidence of single-Dirac-cone like surface states in which Bi2Te3−xSex with Se/Te-substitution leads to tunable surface states. Our results demonstrate that by fine-tuned MBE growth conditions, Bi2Te3−xSex thin film alloys with tunable to...

Streptomycetes are mycelial bacteria that produce sporulating aerial hyphae on solid media. Bald (bld) mutants fail to form aerial mycelium under at least some conditions. bldA encodes the only tRNA species able to read the leucine codon UUA efficiently, implying the involvement of a TTA-containing gene in initiating aerial growth. One candidate for such a gene was bldH, because the bldH109 mutant of Streptomyces coelicolor resembles bldA mutants in some aspects. In the work reported here, adpAc, an S. coelicolor gene similar to the Streptomyces griseus A factor-regulated adpAg, was found to complement the bldH109 mutant partially at both single and multiple copies. The sequence of adpAc from the bldH109 mutant revealed a frameshift. A constructed in frame deletion of adpAc conferred a bald colony phenotype, and the mutant behaved like bldA mutants and bldH109 in its pattern of extracellular signal exchange. Both adpAc and adpAg contain a TTA codon. A TTA-free version of adpAc was engineered by replacing the TTA leucine codon with a cognate TTG leucine codon. The adpA(TTATTG) gene could partially restore aerial mycelium formation to a bldA mutant when it was followed in cis by the gene ornA, as in the natural chromosomal arrangement. This indicated that the UUA codon in adpAc mRNA is the principal target through which bldA influences morphological differentiation. It also implied that translational arrest at the UUA codon in adpAc mRNA caused a polar effect on the downstream ornA, and that the poor translation of both genes contributes extensively to the deficiency of aerial mycelium formation in bldA mutants. Unlike the situation in S. griseus, adpAc transcription does not depend on the host's -butyrolactone signalling system, at least in liquid cultures. In addition, sigma factor BldN, which is the homologue of an S. griseus sigma factor AdsA that is absent from adpAg mutants of S. griseus, was present in the constructed adpAc null mutant of S. coelicolor.

A 2,671 bp DNA carrying a type I PKS module with KS and AT domains from Streptomyces sp. FR-008 was cloned in-frame into the BamHI site immediately downstream of the PT7 promoter of the E. coli expression vector pET-15b, no considerable expression under IPTG induction was detected. The same PKS gene cloned downstream of the tandem PRPL promoters of pBV220 also yielded no over-expression under 42 degrees C induction. This gene was, however, over-expressed when it was cloned downstream of the tandem PRPT7 or PRPLPT7 promoters. In the case of the tandem PRPLPT7 promoters, the over-expression was dependent on the 42 degrees C plus IPTG double induction. While in the case of the tandem PRPT7 promoters, over-expression could be achieved when the gene was induced by IPTG or 42 degrees C individually or by IPTG and 42 degrees C double induction. Based on these experiences an expression vector pHZ330 containing the tandem PRPT7 promoters was constructed. In addition, the PKS protein expressed in E. coli was injected into rabbits to generate PKS-specific antibodies. Western blotting experiment indicated that these antibodies were PKS-specific which could be used either for the study of the PKS gene cluster or for the detection of the heterologous expression of Streptomyces sp. FR-008 PKS genes.

Background Excessive greater splanchnic nerve (GSN) activation contributes to the progression of gastric ischemia-reperfusion (GI-R) injury. This study was designed to investigate the protective mechanism of cerebellar fastigial nucleus (FN) stimulation against GI-R injury. Methods The GI-R injury model was induced in rats by clamping the celiac artery for 30 min, and then reperfusion for 30 min, 1, 3, 6, or 24 h, respectively. Key Results Microinjection of l-Glu (3, 6, 12 μg) into the FN dose-dependently attenuated GI-R injury and GSN activity. In addition, there was an enhancement of gastric mucosal blood flow in GI-R rats. Pretreatment with the glutamic acid decarboxylase antagonist into the FN, the GABAA receptor antagonist into the lateral hypothalamic area or lesion of superior cerebellar peduncle all reversed the protective effects of the FN stimulation. Furthermore, the FN stimulation reduced the TUNEL-positive gastric mucosal cell and Bax-positive gastric mucosal cell in GI-R rats. Conclusions & Inferences These results indicate that the protective effects of the FN stimulation against GI-R injury may be mediated by attenuation of the excessive GSN activation, gastric mucosal cell apoptosis, and Bax expression in GI-R rats.

The 13 kb DNA segment responsible for replication has been isolated from Streptomyces hygroscopicus subsp. yingchengensis strain 10-22 using a pBR322-derived Streptomyces replication-probe vector pIJ2703. The restriction map of the hybrid plasmid, pHZ54, has been constructed. Following a series of deletion and subcloning experiments, the minimal functional region for replication was located within a 2.86 kb DNA fragment. Subsequently, this region was further shortened into a 2 kb region by exonuclease III deletion. A few small bifunctional plasmids able to replicate in E. coli as well as in Streptomyces, were obtained during the above process. Some plasmids could be used as shuttle vectors.