457 research outputs found

    Modulation parameter estimation of LFM interference for direct sequence spread spectrum communication system in alpha-stable noise

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    The linear frequency modulation (LFM) interference is one of the typical broadband interferences in direct sequence spread spectrum (DSSS) communication system. In this article, a novel modulation parameter estimation method of LFM interference is proposed for the DSSS communication system in alpha-stable noise. To accurately estimate the modulation parameters, the alpha-stable noise should be eliminated first. Thus, we formulate a new generalized extended linear chirplet transform to suppress the alpha-stable noise, for a robust time-frequency, transformation of LFM interference is realized. Then, using the Radon transform, the maximum value after transformation and the chirp rate according to the angle related to the maximum value are estimated. In addition, a generalized Fourier transform is introduced to estimate the initial frequency of the LFM interference. For the performance analysis, the CramƩr-Rao lower bounds of the estimated chirp rate and the initial frequency of the LFM interference in the presence of alpha-stable noise are derived. Moreover, the asymptotic properties of the modulation parameter estimator are analyzed. Simulation results demonstrate that the performance of the proposed parameter estimation method significantly outperforms existing methods, especially in a low SNR regime

    Building studentsā€™ entrepreneurial competencies in Chinese universities : diverse learning environment, knowledge transfer, and entrepreneurship education

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    Entrepreneurship education is a critical issue for higher education (HE) students, and thus has been on the agenda of national sustainable development in China. However, few studies have approached the enhancement of HE studentsā€™ entrepreneurial competencies in relation to the perspective of their learning environment. This study developed and employed the Theoretical Model of Entrepreneurial Competencies to examine the path of improving HE studentsā€™ entrepreneurial competencies. The results reveal that a diverse learning environment is an important external factor in developing HE studentsā€™ entrepreneurial competencies. Knowledge transfer, self-efficacy, and cognitive flexibility mediate this relationship. Moreover, entrepreneurship education significantly moderates the effects of self-efficacy on HE studentsā€™ entrepreneurial competencies, but it does not play a moderating role between cognitive flexibility and entrepreneurial competencies. This study provides insights for both policy and managerial endeavors in sustainably advancing HE studentsā€™ entrepreneurship through an innovative learning environment

    Characterizing large-scale weak interlayer shear zones using conditional random field theory

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    The shear behavior of large-scale weak intercalation shear zones (WISZs) often governs the stability of foundations, rock slopes, and underground structures. However, due to their wide distribution, undulating morphology, complex fabrics, and varying degrees of contact states, characterizing the shear behavior of natural and complex large-scale WISZs precisely is challenging. This study proposes an analytical method to address this issue, based on geological fieldwork and relevant experimental results. The analytical method utilizes the random field theory and Kriging interpolation technique to simplify the spatial uncertainties of the structural and fabric features for WISZs into the spatial correlation and variability of their mechanical parameters. The Kriging conditional random field of the friction angle of WISZs is embedded in the discrete element software 3DEC, enabling activation analysis of WISZ C2 in the underground caverns of the Baihetan hydropower station. The results indicate that the activation scope of WISZ C2 induced by the excavation of underground caverns is approximately 0.5ā€“1 times the main powerhouse span, showing local activation. Furthermore, the overall safety factor of WISZ C2 follows a normal distribution with an average value of 3.697

    Detection and Genomic Characterization of a Morganella morganii Isolate From China That Produces NDM-5

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    The increasing prevalence and transmission of the carbapenem resistance gene blaNDMā€“5 has led to a severe threat to public health. So far, blaNDMā€“5 has been widely detected in various species of Enterobacterales and different hosts across various cities. However, there is no report on the blaNDMā€“5ā€“ harboring Morganella morganii. In January 2016, the first NDM-5-producing Morganella morganii L241 was found in a stool sample of a patient diagnosed as recurrence of liver cancer in China. Identification of the species was performed using 16S rRNA gene sequencing. Carbapenemase genes were identified through both PCR and sequencing. To investigate the characteristics and complete genome sequence of the blaNDMā€“5-harboring clinical isolate, antimicrobial susceptibility testing, S1 nuclease pulsed field gel electrophoresis, Southern blotting, transconjugation experiment, complete genome sequencing, and comparative genomic analysis were performed. M. morganii L241 was found to be resistant to broad-spectrum cephalosporins and carbapenems. The complete genome of L241 is made up from both a 3,850,444 bp circular chromosome and a 46,161 bp self-transmissible IncX3 plasmid encoding blaNDMā€“5, which shared a conserved genetic context of blaNDMā€“5 (Ī”IS3000-Ī”ISAba125-IS5-blaNDMā€“5-ble-trpF-dsbC-IS26). BLASTn analysis showed that IncX3 plasmids harboring blaNDM genes have been found in 15 species among Enterobacterales from 13 different countries around the world thus far. In addition, comparative genomic analysis showed that M. morganii L241 exhibits a close relationship to M. morganii subsp. morganii KT with 107 SNPs. Our research demonstrated that IncX3 is a key element in the worldwide dissemination of blaNDM-5 among various species. Further research will be necessary to control and prevent the spread of such plasmids

    The SIK1/CRTC2/CREB1 and TWIST1/PI3K/Akt/GSK3Ī² signaling pathways mediated by microRNA-25-3p are altered in the schizophrenic rat brain

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    Schizophrenia is a group of severe mental disorders. MiR-25-3p was shown to be involved in various neuropsychiatric diseases and can regulate SIK1 and TWIST1. The CRTC2/CREB1 and PI3K/Akt/GSK3Ī² signaling pathways are downstream pathways of SIK1 and TWIST1, respectively. This study investigated whether miR-25-3p-mediated SIK1/CRTC2/CREB1 and TWIST1/PI3K/Akt/GSK3Ī² signaling pathways are present in an animal model relevant to schizophrenia. A schizophrenic rat model was established by using sub-chronic MK-801 administration. An RNA-seq test was performed to examine the differentially expressed genes (DEGs) in the rat prefrontal cortex (PFC). The mRNA levels of miR-25-3p, SIK1, and TWIST in the PFC and caudate putamen (CPu) were assessed by qRT-PCR. Phosphorylation of the SIK1/CRTC2/CREB1 and TWIST1/PI3K/Akt/GSK3Ī² pathways in the two brain regions was examined by Western blots. The RNA-seq data revealed down-regulated miR-25-3p expression and up-regulated SIK1 and TWIST1 mRNA expression induced by MK-801. Additionally, SIK1 and TWIST1 were shown to be possible downstream responders of miR-25-3p in previous studies. qRT-PCR confirmed the changes of miR-25-3p, SIK1, and TWIST1 induced by MK-801 in both brain regions, which, however, was reversed by risperidone. Furthermore, the phosphorylation of the SIK1/CRTC2/CREB1 pathway was repressed by MK-801, whereas the phosphorylation of the TWIST1/PI3K/Akt/GSK3Ī² pathway was increased by MK-801 in either of the two brain regions. Moreover, the altered phosphorylation of these two signaling pathways induced by MK-801 can be restored by risperidone. In conclusion, this study suggests that altered SIK1/CRTC2/CREB1 and TWIST1/PI3K/Akt/GSK3Ī² signaling pathways mediated by miR-25-3p is very likely to be associated with schizophrenia, revealing potential targets for the treatment and clinical diagnosis of schizophrenia

    Sm3+-Mn4+ activated Sr2GdTaO6 red phosphor for plant growth lighting and optical temperature sensing

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    Optical temperature sensing and plant growth lighting multifunctional applications can be realized by red luminescent materials. In this paper, novel Sm3+ and Sm3+-Mn4+ activated Sr2GdTaO6 (SGTO) red phosphors for plant growth and optical temperature sensing were comprehensively analyzed. The phase, luminescence property and thermal stability of the material were tested. For PL performance, SGTO:0.075Sm3+ exhibits the maximum emission intensity in the range (560ā€“670 nm). The emission range of SGTO:0.075Sm3+ after introducing Mn4+ is mainly dark red light emission in the range from 630 to 750 nm, and the optimum dopingconcentration of Mn4+ is determined to be 0.3 %. The emission band of SGTO:0.075Sm3+ and SGTO:0.075Sm3+, 0.003Mn4+ matches the absorption band of the plants. For optical temperature sensing properties, the relative sensitivity (Sr) and absolute sensitivity (Sa) of SGTO:0.075Sm3+, 0.003Mn4+ are 2.94

    CRISPR/Cas9ā€mediated somatic correction of a novel coagulator factor IX gene mutation ameliorates hemophilia in mouse

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    The Xā€linked genetic bleeding disorder caused by deficiency of coagulator factor IX, hemophilia B, is a disease ideally suited for gene therapy with genome editing technology. Here, we identify a family with hemophilia B carrying a novel mutation, Y371D, in the human F9 gene. The CRISPR/Cas9 system was used to generate distinct genetically modified mouse models and confirmed that the novel Y371D mutation resulted in a more severe hemophilia B phenotype than the previously identified Y371S mutation. To develop therapeutic strategies targeting this mutation, we subsequently compared naked DNA constructs versus adenoviral vectors to deliver Cas9 components targeting the F9 Y371D mutation in adult mice. After treatment, hemophilia B mice receiving naked DNA constructs exhibited correction of over 0.56% of F9 alleles in hepatocytes, which was sufficient to restore hemostasis. In contrast, the adenoviral delivery system resulted in a higher corrective efficiency but no therapeutic effects due to severe hepatic toxicity. Our studies suggest that CRISPR/Casā€mediated inĀ situ genome editing could be a feasible therapeutic strategy for human hereditary diseases, although an efficient and clinically relevant delivery system is required for further clinical studies
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