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A family of conforming finite elements are designed on rectangular grids for solving the Reissner-Mindlin plate equation. The rotation is approximated by C1-Qk+1in one direction and C0-Qkin the other direction finite elements. The displacement is approximated by C1-Qk+1,k+1. The method is locking-free without using any projection/reduction operator. Theoretical proof and numerical confirmation are presented.

P- and L-band synthetic aperture radar (SAR) sensors have foliage- and ground-penetrating imaging capabilities and, thus, contribute to missions, such as deforestation monitoring, biomass estimation, and deformation measurements. The spectrums they employed are also allocated to many services, such as radio navigation satellite services, radio location services, telecommunication, and broadcasting, which is prone to generate harmful radio frequency interference (RFI) to SAR including time stationary narrow band (TSNB) and intermittently transmitted wideband (ITWB) versions. Researchers generally perform on-ground processing to mitigate RFIs by which notch filtering is the best known. However, the phenomena of side-lobe uplift and SNR degradation caused by spectral gaps will deteriorate SAR image quality and further affect image interpretation. This article models and characterizes the signature of TSNB and ITWB RFI in P- and L-band SAR, and on this basis, a two-stage approach is developed to mitigate RFI that overcomes the drawbacks of notch filtering-based approaches. In the first stage, a spectrum cancellation-based RFI detector is proposed, which simultaneously locates RFI and produces an orthogonal projection operator. In the second stage, a low-rank approximation model regulated by truncated nuclear norm, which is solved by the alternating direction method of multipliers, is established to recover the missing spectral information. Experiments are conducted extensively on simulated data as well as real-world data collected by advanced land observing satellite phased-array L-band synthetic aperture radar system and a P-band airborne SAR system to validate the proposed approach.

In this paper, we examine a bivariate insurance risk model that incorporates two distinct business lines. The model encompasses both independent aggregate claims and common shocks to represent the interdependence between losses in these two lines of business. The monitoring of the bivariate risk model occurs periodically, with constant inter-observation intervals. During each observation, dividends may be distributed using a barrier strategy in both business lines. To evaluate the expected present value of operating costs until ruin, we employ the two-dimensional Fourier-cosine series expansion as an approximation technique. The paper derives explicit approximation formulas and conducts an analysis of the approximation errors. In addition, numerous numerical results are presented to demonstrate the effectiveness of our method, and we examine the impacts of various parameters in the model. At the same time, we also study the problem of capital allocation and the optimal dividend barrier problem for bivariate processes.

The electromagnetic environment is becoming complex as the usable spectrum will be allocated for more services. As a result of this situation synthetic aperture radar (SAR) missions are frequently perturbed by radio frequency interference (RFI) that jeopardizes their scientific observations all over the world. The state-of-the-art multichannel SAR has anti-RFI capability since it’s capable of digitally modulating the antenna pattern (AP) in postprocessing, thereby steering the null toward the angle of arrival (AOA) of the RFI in the spatial domain. However, the AOA of RFI is space-variant, meaning that the mitigation performance of beamformers sensitive to AOA will greatly deteriorate. In addition, the AOA of in-swath RFI and the target echo arrive simultaneously, thus the traditional beamformer will generate a distorted AP, deteriorating the SAR imagery. In light of these considerations, this article studies the in-swath and out-of-swath RFIs in elevation multichannel SAR and develops their countermeasures. Thereinto, a least $\ell _{1}$ -norm model is developed to estimate the AOA of the RFI, followed by two schemes developed to separate the RFI. The former develops a beamformer that joint sidelobe control and null expanding to mitigate the space-variant out-of-swaths RFI, whereas the latter develops a blind source separation (BSS)-based technology to mitigate in-swath RFI, avoiding AP distortion and restoring SAR imagery. The effectiveness of the proposed approaches is supported by experiments based on the measured X-band airborne DBF-SAR data as well as the simulated SAR data.

Digital beamforming (DBF) is an effective approach for accessing high-resolution wide-swath (HRWS) imaging in spaceborne synthetic aperture radar (SAR). By utilizing DBF, the performance of imaging, including signal-to-noise ratio (SNR) and system sensitivity, can be greatly improved. In actual missions, DBF for SAR imaging can be combined with various operating modes like squint-strip SAR, spotlight SAR, and TOPSAR. In squint-looking scenarios, the receiving beam of the antenna scans the scene not only along the vertical direction (elevation) but also along the horizontal direction (azimuth). For the first time, this article proposes the application of DBF for squint SAR imaging, establishes a geometric model of beam scanning, and derives the analytic expression of the signal model. The performance of both the conventional DBF scheme and the digital scalloped beamforming (DSBF) scheme is analyzed in squint-looking scenarios. In order to further reduce the loss of gain when processing received signals with broadband widths and long pulse durations in the conventional DBF schemes, as well as to minimize the digital resource consumption in the DSBF scheme, where the resource usage is directly proportional to the number of subbeams, a novel multibeam DBF scheme is proposed. Theoretical analysis and simulation results validate the effectiveness of the proposed scheme, making it as a more realistic technology for future spaceborne SAR.

Fish show variation in feeding habits to adapt to complex environments. However, the genetic basis of feeding preference and the corresponding metabolic strategies that differentiate feeding habits remain elusive. Here, by comparing the whole genome of a typical carnivorous fish (Leiocassis longirostrisGu¨nther) with that of herbivorous fish, we identify 250 genes through both positive selection and rapid evolution, including taste receptor taste receptor type 1 member 3(tas1r3) and trypsin. We demonstrate that tas1r3is required for carnivore preference in tas1r3-deficient zebrafish and in a diet-shifted grass carp model. We confirm that trypsin correlates with the metabolic strategies of fish with distinct feeding habits. Furthermore, marked alterations in trypsin activity and metabolic profiles are accompanied by a transition of feeding preference in tas1r3-deficient zebrafish and diet-shifted grass carp. Our results reveal a conserved adaptation between feeding preference and corresponding metabolic strategies in fish, and provide novel insights into the adaptation of feeding habits over the evolution course.

Infectious diseases caused by pathogenic bacteria are a serious threat to global public health. Nowadays, antibiotics and other clinical drugs suffer from some fundamental disadvantages such as narrow-spectrum antibacterial effect and the risk to induce drug resistance, while inorganic functional nanomaterials with biological catalytic activities have been developed as novel antibacterial agents. In this study, we prepared two-dimensional ultrathin vanadium oxide nanosheets (VOxNSs) with mixed valence states from the oxidised layer of vanadium powder (bulk V) by ultrasonically assisted liquid exfoliation. By conveniently switching between VIVand VV, VOxNSs can efficiently catalyse H2O2enriched in bacterially infected areas to generate hydroxyl radicals (·OH), which induce bacterial oxidative stress and apoptosis. This process can occur in both weakly alkaline and acidic environments, thus being independent of the pH value in infection areas. In addition, contributed by the intrinsic characteristics of vanadium, two-dimensional morphology and reasonable valence state ratios, VOxNSs exhibit the advantages of broad antibacterial spectrum, high catalytic activity and non-toxic by-products. This novel nanosheet offers a new strategy to heal infected wounds and extends the application of nanocatalytic medicine towards anti-infection.