Background Sudden sensorineural hearing loss(SSNHL)is a common disease in otology,and steroids play an important role in its treatment.Steroids can be administered systemically or locally,and the efficacies of differe...Background Sudden sensorineural hearing loss(SSNHL)is a common disease in otology,and steroids play an important role in its treatment.Steroids can be administered systemically or locally,and the efficacies of different administration routes remain controversial.Methods We searched the Cochrane,EMBASE,PubMed,Web of Science,CNKI,Wanfang and Weipu databases for randomized controlled trials(RCTs)on glucocorticoid treatments for SSNHL to compare the efficacy of topical and systemic steroid administration.The Review Manager 5.4 software was used for synthesis of data:the rate of reported hearing improvement and change in pure-tone audiometry(PTA).Results In all the included studies,when intratympanic administration was compared to systemic therapies,the risk difference(RD)using reported hearing improvement as an outcome measure was 0.08(95%CI:0.01–0.14,I2=45%).Using PTA changes as an outcome measure in 4 studies,the mean difference(MD)was 10.43 dB(95%CI:3.68–17.18,I2=81%).Hearing improvement RD was also compared among different types of steroid,recovery criteria,follow-up times and diagnostic criteria,and showed no significant differences exception for recovery criteria(>10 dB)(RD-0.06,95%CI:0.14-0.2,I2=0%).Conclusion As the initial treatment for SSNHL,topical steroids seem to be superior to systemic steroid administration,especially in patients with contraindications to systemic steroids usage.However,further verification based on high-quality research is needed.展开更多
The methylammonium lead triiodide(CH_(3)NH_(3)PbI_(3))-based perovskite shows a great alluring prospect in areas of solar cells, lasers, photodetectors, and light emitting diodes owing to their excellent optical and e...The methylammonium lead triiodide(CH_(3)NH_(3)PbI_(3))-based perovskite shows a great alluring prospect in areas of solar cells, lasers, photodetectors, and light emitting diodes owing to their excellent optical and electrical advantages. However,it is very sensitive to the surrounding oxygen and moisture, which limits its development seriously. It is urgent to spare no effort to enhance its optical and electrical stability for further application. In this paper, we synthesize the MAPbI_(3) perovskite film on the glass substrate with/without the ionic liquid(IL) of 1-Butyl-3-methylimidazolium tetrafluoroborate(BMIMBF_(4)) by a simple two-step sequential solution method. The additive of BMIMBF_(4)can improve the quality of crystal structure. Moreover, the photo-luminescence(PL) intensity of MAPbI_(3) film with BMIMBF_(4) is much stronger than the pure MAPbI_(3) film after a week in the air, which is almost ten-fold of the pure one. Meanwhile, under the illumination of 405-nm continuous wave(CW) laser, the fluorescent duration of the MAPbI_(3) film with BMIMBF_(4) is approximately 2.75 min, while the pure MAPbI;film is only about 6 s. In fact, ionic liquid of BMIMBF_(4) in the perovskite film plays a role of passivation, which prevents the dissolution of MAPbI_(3) into CH_(3)NH_(3)and PbI_(2) and thus enhances the stability of environment. In addition, the ionic liquid of BMIMBF;possesses high ionic conductivity, which accelerates the electron transport, so it is beneficial for the perovskite film in the areas of solar cells, photodetectors, and lasers. This interesting experiment provides a promising way to develop the perovskite’s further application.展开更多
In recent years,with the development of society and the progress of science and technology,online learning has penetrated into people’s daily life,and people’s demand for high-quality curriculum products is more and...In recent years,with the development of society and the progress of science and technology,online learning has penetrated into people’s daily life,and people’s demand for high-quality curriculum products is more and more strong.From a macro perspective,the continuous growth of national financial investment in education,the continuous upgrading of China’s consumption structure,the development of 5G technology and the popularization of AI intelligence make online teaching less limited.The online education industry is showing an explosive growth trend.More and more online education institutions are listed for financing,and the market value is soaring.However,in 2019,except for GSX,the latest online learning platforms such as New Oriental,Speak English Fluently and Sunlands,have been in a state of loss.Most of these agencies seize the market by increasing advertising investment,but at the same time,they also bring huge marketing costs,which affect the financial performance of the company.With the enhancement of Matthew effect,largescale educational institutions occupy a large market through free classes and low-price classes,while small and medium-sized institutions with weak capital strength are often unable to afford high sales costs,facing the risk of capital chain rupture.Taking new Oriental online as an example,this paper analyzes the problems existing in the marketing strategies of online education institutions.It also puts forward suggestions on four aspects,which are target market,differentiated value,marketing mix and marketing mode,so as to make sure that online education institutions can control marketing expenses and achieve profits by improving course quality,expanding marketing channels and implementing precise positioning.展开更多
To further promote the achievable average secrecy rate for UAV-ground communications, a UAV-aided mobile jamming strategy was proposed in this paper. Specifically, an additional cooperative UAV is employed as a mobile...To further promote the achievable average secrecy rate for UAV-ground communications, a UAV-aided mobile jamming strategy was proposed in this paper. Specifically, an additional cooperative UAV is employed as a mobile jammer to transmit the jamming signal to help keep the source UAV closer to the ground destination, thus establishing more favorable legitimate link and enhancing the secrecy performance. We aimed to maximize the achievable secrecy rate by jointly optimizing the trajectories and transmit power of both source UAV and jammer UAV. To solve the considered non-convex optimization problem, we presented a block coordinate descent based iterative algorithm to address a sequence of approximated convex problems for the optimized parameter block by block to find a local optimal solution. Numerical results verify that the proposed algorithm can achieve significant secrecy rate gain compared to all the benchmark schemes.展开更多
文摘Background Sudden sensorineural hearing loss(SSNHL)is a common disease in otology,and steroids play an important role in its treatment.Steroids can be administered systemically or locally,and the efficacies of different administration routes remain controversial.Methods We searched the Cochrane,EMBASE,PubMed,Web of Science,CNKI,Wanfang and Weipu databases for randomized controlled trials(RCTs)on glucocorticoid treatments for SSNHL to compare the efficacy of topical and systemic steroid administration.The Review Manager 5.4 software was used for synthesis of data:the rate of reported hearing improvement and change in pure-tone audiometry(PTA).Results In all the included studies,when intratympanic administration was compared to systemic therapies,the risk difference(RD)using reported hearing improvement as an outcome measure was 0.08(95%CI:0.01–0.14,I2=45%).Using PTA changes as an outcome measure in 4 studies,the mean difference(MD)was 10.43 dB(95%CI:3.68–17.18,I2=81%).Hearing improvement RD was also compared among different types of steroid,recovery criteria,follow-up times and diagnostic criteria,and showed no significant differences exception for recovery criteria(>10 dB)(RD-0.06,95%CI:0.14-0.2,I2=0%).Conclusion As the initial treatment for SSNHL,topical steroids seem to be superior to systemic steroid administration,especially in patients with contraindications to systemic steroids usage.However,further verification based on high-quality research is needed.
基金Project supported by the National Key Research and Development Program of China (Grant No. 2018YFC2001100)the Natural National Science Foundation of China (Grant No. 61574017)+1 种基金the Fundamental Research Funds for Central Universities, China (Grant No. 2017CX10007)the Open Foundation of Guangxi Key Laboratory of Processing for Non-ferrous Metals and Featured Materials, Guangxi University (Grant No. 2020GXYSOF08)。
文摘The methylammonium lead triiodide(CH_(3)NH_(3)PbI_(3))-based perovskite shows a great alluring prospect in areas of solar cells, lasers, photodetectors, and light emitting diodes owing to their excellent optical and electrical advantages. However,it is very sensitive to the surrounding oxygen and moisture, which limits its development seriously. It is urgent to spare no effort to enhance its optical and electrical stability for further application. In this paper, we synthesize the MAPbI_(3) perovskite film on the glass substrate with/without the ionic liquid(IL) of 1-Butyl-3-methylimidazolium tetrafluoroborate(BMIMBF_(4)) by a simple two-step sequential solution method. The additive of BMIMBF_(4)can improve the quality of crystal structure. Moreover, the photo-luminescence(PL) intensity of MAPbI_(3) film with BMIMBF_(4) is much stronger than the pure MAPbI_(3) film after a week in the air, which is almost ten-fold of the pure one. Meanwhile, under the illumination of 405-nm continuous wave(CW) laser, the fluorescent duration of the MAPbI_(3) film with BMIMBF_(4) is approximately 2.75 min, while the pure MAPbI;film is only about 6 s. In fact, ionic liquid of BMIMBF_(4) in the perovskite film plays a role of passivation, which prevents the dissolution of MAPbI_(3) into CH_(3)NH_(3)and PbI_(2) and thus enhances the stability of environment. In addition, the ionic liquid of BMIMBF;possesses high ionic conductivity, which accelerates the electron transport, so it is beneficial for the perovskite film in the areas of solar cells, photodetectors, and lasers. This interesting experiment provides a promising way to develop the perovskite’s further application.
文摘In recent years,with the development of society and the progress of science and technology,online learning has penetrated into people’s daily life,and people’s demand for high-quality curriculum products is more and more strong.From a macro perspective,the continuous growth of national financial investment in education,the continuous upgrading of China’s consumption structure,the development of 5G technology and the popularization of AI intelligence make online teaching less limited.The online education industry is showing an explosive growth trend.More and more online education institutions are listed for financing,and the market value is soaring.However,in 2019,except for GSX,the latest online learning platforms such as New Oriental,Speak English Fluently and Sunlands,have been in a state of loss.Most of these agencies seize the market by increasing advertising investment,but at the same time,they also bring huge marketing costs,which affect the financial performance of the company.With the enhancement of Matthew effect,largescale educational institutions occupy a large market through free classes and low-price classes,while small and medium-sized institutions with weak capital strength are often unable to afford high sales costs,facing the risk of capital chain rupture.Taking new Oriental online as an example,this paper analyzes the problems existing in the marketing strategies of online education institutions.It also puts forward suggestions on four aspects,which are target market,differentiated value,marketing mix and marketing mode,so as to make sure that online education institutions can control marketing expenses and achieve profits by improving course quality,expanding marketing channels and implementing precise positioning.
基金partly supported by National Natural Science Foundation of China (No. 41504026, 61362009)Natural Science Foundation of Jiangxi (No.20152ACB21003)Foundation for Distinguished Young Talents Training Programme of Jiangxi (No.20171BCB23006)
文摘To further promote the achievable average secrecy rate for UAV-ground communications, a UAV-aided mobile jamming strategy was proposed in this paper. Specifically, an additional cooperative UAV is employed as a mobile jammer to transmit the jamming signal to help keep the source UAV closer to the ground destination, thus establishing more favorable legitimate link and enhancing the secrecy performance. We aimed to maximize the achievable secrecy rate by jointly optimizing the trajectories and transmit power of both source UAV and jammer UAV. To solve the considered non-convex optimization problem, we presented a block coordinate descent based iterative algorithm to address a sequence of approximated convex problems for the optimized parameter block by block to find a local optimal solution. Numerical results verify that the proposed algorithm can achieve significant secrecy rate gain compared to all the benchmark schemes.
