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Doubled haploid (DH) technology is an important tool in crop breeding because it can significantly accelerate the breeding process. ZmPLA1/MATL/NLDand ZmDMPare two key genes controlling haploid induction (HI) in maize, exhibiting a synergistic effect. However, it is unknown whether knock out of ZmDMP orthologs can stimulate HI in rice. In this study, a ZmPLA1ortholog (OsPLA1) and two ZmDMPorthologs (OsDMP3and OsDMP6) were identified in rice. All three genes encode plasma membrane-localized proteins and were highly expressed in mature anthers. Knockout of OsPLA1in both Minghui 63 and Nipponbare resulted in reduced seed setting rate (SSR) and caused HI. The osdmp3, osdmp6and the double mutant failed to trigger HI independently, nor increased the haploid induction rate (HIR) when combined with ospla1. Repeated pollinations operations of QX654A with the ospla1mutant significantly improve SSR, while reducing HIR. RNA-seq profiling of mature ospla1mutant anthers indicated that a large number of differentially expressed genes (DEGs) were enriched in redox homeostasis and lipid metabolic GO terms, plant hormone signal transduction, and MAPK signaling pathways. These findings provide important insights towards construction of an efficient DH breeding technology and study of the molecular mechanism of HI in rice.

The measured uniaxial-head load spectrum in the road simulation test has a large number of useless small loads. When applying the measured load spectrum directly, it will take a lot of time. This paper designs a comprehensive road spectrum measurement system to collect data and proposes a method for editing the uniaxial-head acceleration load spectrum using short-time Fourier transform to speed up the reliability test process and reduce time costs. In this method, the time domain and frequency domain information of the signal is obtained by short-time Fourier transform. The concept of accumulated power spectral density is proposed to identify the reduced load data, and the relative fatigue damage is used as the pass criterion. The length of the edited spectrum is only 66% of the original spectrum through the above-mentioned editing method and retains the relative damage amount of 91%. Finally, through the analysis of time domain, frequency domain, and fatigue statistical parameters, it demonstrates that the short-time Fourier transform–based acceleration load spectrum edition method could achieve a similar fatigue damage to the original spectrum in a shorter time.

Doubled haploid (DH) breeding based on in vivo haploid induction has led to a new approach for maize breeding1. All modern haploid inducers used in DH breeding are derived from the haploid inducer line Stock6. Two key quantitative trait loci, qhir1and qhir8, lead to high-frequency haploid induction2. Mutation of the gene MTL/ZmPLA1/NLDin qhir1could generate a ~2% haploid induction rate (HIR)3–5; nevertheless, this mutation is insufficient for modern haploid inducers whose average HIR is ~10%6. Therefore, cloning of the gene underlying qhir8is important for illuminating the genetic basis of haploid induction. Here, we present the discovery that mutation of a non-Stock6-originating gene in qhir8, namely, ZmDMP, enhances and triggers haploid induction. ZmDMPwas identified by map-based cloning and further verified by CRISPR–Cas9-mediated knockout experiments. A single-nucleotide change in ZmDMPleads to a 2–3-fold increase in the HIR. ZmDMPknockout triggered haploid induction with a HIR of 0.1–0.3% and exhibited a greater ability to increase the HIR by 5–6-fold in the presence of mtl/zmpla1/nld. ZmDMPwas highly expressed during the late stage of pollen development and localized to the plasma membrane. These findings provide important approaches for studying the molecular mechanism of haploid induction and improving DH breeding efficiency in maize. By map-based cloning and knockout experiments, a study identified and validated ZmDMPto be one of the two genes known to control haploid induction in maize. A single-nucleotide mutation in ZmDMPcauses a 2–3-fold increase in the haploid induction rate.

For time-of-flight positron emission tomography detectors, time-to-digital converters (TDCs) are essential to resolve the coincidence time of the photon pairs. Recently, an efficient TDC structure called ring-oscillator-based (RO-based) Vernier TDC using carry chains was reported by our team. The method is very promising due to its low linearity error and low resource cost. However, the implementation complexity is rather high especially when moving to multichannels TDC designs, since this method calls for a manual intervention to the initial fitting results of the compilation software. In this paper, we elaborate the key points toward implementing high performance multichannels TDCs of this kind while keeping the least implementation complexity. Furthermore, we propose an efficient fine time interpolator construction method called the period difference recording which only needs at most 31 adjustment trials to obtain a targeted TDC resolution. To validate the techniques proposed in this paper, we built a 32-channels TDC on a Stratix III field programmable gate array chip and fully evaluated its performance. Code density tests show that the obtained resolution results lie in the range of (23-37 ps), the differential nonlinearity results lie in the range of [-0.4-0.4 least significant bit (LSB)] and the integral nonlinearity results lie in the range of (-0.7-0.7 LSB) for each of the 32 TDC channels. This paper greatly eases the designing difficulty of the carry chain RO-based TDCs and can significantly propel their development in practical use.

The flow around a body of revolution with an appendage controlled by electromagnetic force is calculated by a finite volume method in order to assess the influence of the appendage on the flow and the control effect of the electromagnetic force. The Reynolds number (Re) base on the hull length is 1.0 × 107. An electromagnetic actuator is flush-mounted on the surface of the appendage to generate streamwise eletromagnetic force (Lorentz force) for flow control. The flow around the body at straight course and 6° yaw controlled by Lorentz force is simulated and discussed. The results indicate that the elliptical appendage introduces a complex wake structure and force fluctuation. The wake of the appendage has less influence on the boundary layer of the body at 6° yaw than at straight course. When the Reynolds number is as high as 1.0 × 107, the flow field and dynamic characteristic of the body approximate to the Euler solution. The Lorentz force may suppress the near-wall separation from the appendage effectively and reduce the drag and vibration, especially in the straight course case.

In this paper, a frequency domain non-stationary vibration spectrum simulation reconstruction method is proposed, which based on Fuzzy C-Means (FCM) clustering wavelet packet coefficient matrix reconstruction. The factors such as the non-stationarity of the road surface excitation and vibration response of the vehicle due to the time variation of the vehicle speed and the nonlinearity of the coupled vibration of the vehicle body during the running of the wheeled vehicle are considered. In this method, the one-dimensional measured vibration spectrum reconstruction problem is turned into the two-dimensional wavelet packet coefficient matrix (image) reconstruction problem by wavelet packet transform. Furthermore, based on the FCM clustering principle of wavelet packet coefficient normalized column vector, some non-stationary features in the frequency domain was extracted to realize the frequency domain non-stationary reconstruction of the measured road spectrum, including the important vibration types contained in the measured vibration spectrum and the total probability of occurrence and the adjacent conditional probability, and the dispersion around the cluster center in each type. Through the comparison with the measured road spectrum, the method was verified that it can accurately simulate the actual road driving conditions of the wheeled vehicle. The reconstructed road spectrum this method provided is consistent with the actual working conditions for road simulation experiments.