Phase recovery,calculating the phase of a light wave from its intensity measurements,is essential for various applications,such as coherent diffraction imaging,adaptive optics,and biomedical imaging.It enables the rec...Phase recovery,calculating the phase of a light wave from its intensity measurements,is essential for various applications,such as coherent diffraction imaging,adaptive optics,and biomedical imaging.It enables the reconstruction of an object’s refractive index distribution or topography as well as the correction of imaging system aberrations.In recent years,deep learning has been proven to be highly effective in addressing phase recovery problems.The two most direct deep learning phase recovery strategies are data-driven(DD)with supervised learning mode and physics-driven(PD)with self-supervised learning mode.DD and PD achieve the same goal in different ways yet there is a lack of necessary research to reveal similarities and differences.Therefore,we comprehensively compare these two deep learning phase recovery strategies in terms of time consumption,accuracy,generalization ability,ill-posedness adaptability,and prior capacity.What is more,we propose a co-driven strategy of combining datasets and physics for the balance of high-and low-frequency information.展开更多
Background Clinical meaning of recovery phase limited ST segment depression of a treadmill exercise test is controversial.The aim of this study was to re-assess the diagnostic and prognostic value of ST segment depres...Background Clinical meaning of recovery phase limited ST segment depression of a treadmill exercise test is controversial.The aim of this study was to re-assess the diagnostic and prognostic value of ST segment depression during the recovery phase with the active phase of a treadmill exercise test in suspected coronary artery disease patients.Methods Clinical,exercise and angiographic data were retrospectively collected from 602 patients in the study.Five hundred and seventy-six patients developed ST segment depression during the active phase of the treadmill exercise test （group 1） and 26 patients developed ST segment depression only during the recovery phase （group 2）.Results With similar major clinical features,the prevalence of significant coronary artery stenosis and average Gensini scores were lower in the recovery phase-limited depression patients （group 2 vs.group 1,50.0% vs.66.9%,P=0.031 and group 2 vs.group 1,1.5 vs.8.5,P=0.04）.At a median follow up of 50.9 months for 22 group 2 and 34.8 months for 438 group 1 patients,the prevalence of total cardiac events was higher in group 1 than in group 2 patients （RR 1.60,95% Cl 1.00-2.54,P=0.049）.Conclusion The present study provides preliminary evidence that the diagnostic and prognostic value of recovery phaselimited ST segment depression of treadmill exercise test is limited.展开更多
Severe acute respiratory syndrome (SARS) is an acute respiratory infectious disease caused by a novel coronavirus, firstly broke out in November 2002 in Guangdong and prevailed quickly in Beijing, Hong Kong, Taiwan an...Severe acute respiratory syndrome (SARS) is an acute respiratory infectious disease caused by a novel coronavirus, firstly broke out in November 2002 in Guangdong and prevailed quickly in Beijing, Hong Kong, Taiwan and other regions of China. It was one of the most potential pandemic diseases and had affected more than 20 other countries.^(1,2) There have been a lot of resear-ches^(2-7) in terms of its etiology, epidemiology, pathogenesis, clinical characteristics, diagnostics, treatment and prevention, vaccines and so on.Along with control of the epidemic situation, a great number of SARS patients were in the recovery phase, therefore, we undertook a half-year follow-up investigation on their clinical, laboratory and image situations.展开更多
The dynamic characteristic of complex network failure and recovery is one of the main research topics in complex networks. Real world systems such as traffic jams and Internet recovery could be described by the comple...The dynamic characteristic of complex network failure and recovery is one of the main research topics in complex networks. Real world systems such as traffic jams and Internet recovery could be described by the complex network theory. We propose a model to study the recovery process in complex networks. Two different recovery mechanisms are considered in three kinds of networks： external recovery and internal recovery. By simulating the process of the nodes recovery in networks, it is found that the system exhibits the feature of first-order phase transition only when the external recovery is considered. Internal recovery cannot induce such a kind of transitions. As external recovery and internal recovery coexist on networks, the systems will retain the most efficient part of external recovery and internal recovery. Meanwhile, a hysteresis could be observed when increasing or decreasing the failure probability. Finally, a largest degree node protection strategy is proposed for improving the robustness of networks.展开更多
Salt stress might be an important factor that decreases the emergence of seedlings and reduces plants'growth,causing their endangered status.However,the effects of salt stress on the germination of the Mediterrane...Salt stress might be an important factor that decreases the emergence of seedlings and reduces plants'growth,causing their endangered status.However,the effects of salt stress on the germination of the Mediterranean species are less concern.Limonium strictissimum(Salzm.)Arrigoni,part of the group related to Limonium articulatum(Loisel.)Kuntze,is a Cyrno-Sardinian endemism,which is included in the International Union for Conservation of Nature(IUCN)Red Lists as Endangered(EN).Fresh seeds of L.strictissimum harvested from the only known population in Sardinia and a population in southeastern Corsica were used with the aims to study the effects of temperature and salinity on the seed germination and to evaluate the ability to recover their germination after exposure to salt stress.In both populations,empty fruits with a lower percentage were observed in Sardinia than in Corsica.The seeds showed a high germination capacity,which was not influenced by temperature and did not even differ between the two populations.Compared with non-saline condition,the presence of salt in the substrate,independently of the concentration tested,inhibited seed germination in both populations,with germination percentages never exceeding 40%.The Sardinian population showed a recovery capacity after exposure to high salt stress,always above 50%regardless of the salt concentration and incubation temperature considered.The seeds previously exposed to 125 mM NaCl at 30℃ had the lowest recovery percentage(56%),while the highest recovery percentage(84%)was recorded at 25℃ with a concentration of 250 mM NaCl.Differently,the Corsican population recorded a higher recovery percentage(54%)in seeds previously exposed to 500 mM NaCl at 20℃,while for the concentration of 125 mM NaCl,the best recovery percentage(11%)was recorded at 30℃.The ability of L.strictissimum to recover germination after salt exposure can be interpreted as an adaptation to the coastal habitats in which it grows.This study provides new insights into the ecophysiology of L.strictissimum seed germination,which could help preserve and implement effective conservation measures for this endangered species with restricted populations.展开更多
In this paper,a quadrature phase shift keying(QPSK)phase-recovery algorithm is presented for coherent intersatellite optical wireless communication(Is OWC).From a theoretical perspective,we explain the process of the ...In this paper,a quadrature phase shift keying(QPSK)phase-recovery algorithm is presented for coherent intersatellite optical wireless communication(Is OWC).From a theoretical perspective,we explain the process of the multiplier-free algorithm.Through simulations,we analyze key parameters and provide guidance on their optimal selection.Additionally,the proposed algorithm maintains stable phase tracking at bit energy to noise power spectral density(Eb/N0)as low as 4 d B.In an ob2b transmission test,our algorithm achieved a sensitivity of-49 d Bm@5 Gbps QPSK[hard-decision forward-errorcorrection(HD-FEC)limit].Compared to the Viterbi and Viterbi phase-recovery(V&V)algorithm,its receiving sensitivity is improved by 1 d B,resulting in a link distance extension of 1100 km.Our multiplier-free and robust algorithm meets the requirements of Is OWC systems and shows promise for future applications.展开更多
An adaptive algorithm named low complexity phase off- set estimation （LC-POE） is proposed for orthogonal frequency division multiplexing （OFDM） signals. Depending on the requirement, the estimation procedure is di...An adaptive algorithm named low complexity phase off- set estimation （LC-POE） is proposed for orthogonal frequency division multiplexing （OFDM） signals. Depending on the requirement, the estimation procedure is divided into several scales to accelerate the adaptive convergence speed and ensure the estimation accuracy. The true phase offset is estimated through shrinking the detection range and raising the resolution scale step by step. Both the convergence performance and complexity are discussed in the paper. Simulation results show the effectiveness of the proposed algorithm. The LC-POE algorithm is promising in the application of OFDM systems.展开更多
OBJECTIVE:To evaluate the effectiveness and safety of Xiangsha Liujun pills(香砂六君丸) on the decreased digestive function in patients in the recovery phase of the Coronavirus disease 2019(COVID-19).METHODS:A randomi...OBJECTIVE:To evaluate the effectiveness and safety of Xiangsha Liujun pills(香砂六君丸) on the decreased digestive function in patients in the recovery phase of the Coronavirus disease 2019(COVID-19).METHODS:A randomized,double blind,placebo controlled clinical trial was conducted.A total of 200 COVID-19 patients in the recovery phase were included in our study in Ezhou Hospital of Traditional Chinese Medicine.Totally 200 subjects were randomly divided into a treatment group(Xiangsha Liujun pills) and a control group(placebo),with 100 in each group.Subjects took Xiangsha Liujun pills or placebo orally three times a day for two weeks.Three visits were scheduled at week 0(baseline),week 1(the middle of the intervention) and week 2(the end of the intervention) for each eligible patient.The total efficacy rates for improving the Traditional Chinese Medicine(TCM) symptoms(fatigue,poor appetite,abdominal distension and loose stools) and the disappearance rates of symptoms were observed and compared in the treatment and control groups.Adverse events were recorded during the study period.SAS 9.4 was used to analyze the data.RESULTS:A total of 200 patients were included in this study,among which 4 participants withdrew because the drugs did not work.Three patients were excluded for age.Before the treatment,there was no significant difference between the TCM symptoms scores of subjects.After 1 week of treatment,the full analysis set(FAS) showed that the efficacy rates for abdominal distension and loose stools in the treatment group were significantly higher than the control group(P < 0.05).There were no significant differences in the efficacy rates for fatigue and poor appetite between the two groups(P > 0.05).In addition,the disappearance rate of fatigue in the treatment group was significantly higher than the control group(P < 0.05);there were no significant differences between the two groups after treatment in the rates of poor appetite,abdominal distension,and loose stools(P > 0.05).After 2 weeks of treatment,the efficacy rates for fatigue,poor appetite,abdominal distension,and loose stools in the treatment group were significantly higher than the control group(P < 0.05).The disappearance rate of loose stools in the treatment group was significantly higher than the control group(P < 0.05).However,there were no significant differences in the disappearance rates of fatigue,poor appetite,and abdominal distension between the two groups(P > 0.05).No severe adverse events were reported by subjects during the study.CONCLUSIONS:This clinical study confirmed that Xiangsha Liujun pills can effectively improve the symptoms related to the decreased digestive function in COVID-19 convalescent patients.展开更多
Phase recovery from intensity-only measurements forms the heart of coherent imaging techniques and holography.In this study,we demonstrate that a neural network can learn to perform phase recovery and holographic imag...Phase recovery from intensity-only measurements forms the heart of coherent imaging techniques and holography.In this study,we demonstrate that a neural network can learn to perform phase recovery and holographic image reconstruction after appropriate training.This deep learning-based approach provides an entirely new framework to conduct holographic imaging by rapidly eliminating twin-image and self-interference-related spatial artifacts.This neural network-based method is fast to compute and reconstructs phase and amplitude images of the objects using only one hologram,requiring fewer measurements in addition to being computationally faster.We validated this method by reconstructing the phase and amplitude images of various samples,including blood and Pap smears and tissue sections.These results highlight that challenging problems in imaging science can be overcome through machine learning,providing new avenues to design powerful computational imaging systems.展开更多
BACKGROUND Synthetic magnetic resonance imaging(MRI)MAGnetic resonance imaging compilation(MAGiC)is a new MRI technology.Conventional T1,T2,T2-fluidattenuated inversion recovery(FLAIR)contrast images,quantitative imag...BACKGROUND Synthetic magnetic resonance imaging(MRI)MAGnetic resonance imaging compilation(MAGiC)is a new MRI technology.Conventional T1,T2,T2-fluidattenuated inversion recovery(FLAIR)contrast images,quantitative images of T1 and T2 mapping,and MAGiC phase sensitive inversion recovery(PSIR)Vessel cerebrovascular images can be obtained simultaneously through post-processing at the same time after completing a scan.In recent years,studies have reported that MAGiC can be applied to patients with acute ischemic stroke.We hypothesized that the synthetic MRI vascular screening scheme can evaluate the degree of cerebral artery stenosis in patients with acute ischemic stroke.AIM To explore the application value of vascular images obtained by synthetic MRI in diagnosing acute ischemic stroke.METHODS A total of 64 patients with acute ischemic stroke were selected and examined by MRI in the current retrospective cohort study.The scanning sequences included traditional T1,T2,and T2-FLAIR,three-dimensional time-of-flight magnetic resonance angiography(3D TOF MRA),diffusion-weighted imaging(DWI),and synthetic MRI.Conventional contrast images(T1,T2,and T2-FLAIR)and intracranial vessel images(MAGiC PSIR Vessel]were automatically reconstructed using synthetic MRI raw data.The contrast-to-noise ratio(CNR)values of traditional T1,T2,and T2-FLAIR images and MAGiC reconstructed T1,T2,and T2-FLAIR images in DWI diffusion restriction areas were measured and compared.MAGiC PSIR Vessel and TOF MRA images were used to measure and calculate the stenosis degree of bilateral middle cerebral artery stenosis areas.The consistency of MAGiC PSIR Vessel and TOF MRA in displaying the degree of vascular stenosis with computed tomography angiography(CTA)was compared.RESULTS Among the 64 patients with acute ischemic stroke,79 vascular stenosis areas showed that the correlation between MAGiC PSIR Vessel and CTA(r=0.90,P<0.01)was higher than that between TOF MRA and CTA(r=0.84,P<0.01).With a degree of vascular stenosis>50%assessed by CTA as a reference,the area under the receiver operating characteristic(ROC)curve of MAGiC PSIR Vessel[area under the curve(AUC)=0.906,P<0.01]was higher than that of TOF MRA(AUC=0.790,P<0.01).Among the 64 patients with acute ischemic stroke,39 were scanned for traditional T1,T2,and T2-FLAIR images and MAGiC images simultaneously,and CNR values in DWI diffusion restriction areas were measured,which were:Traditional T2=21.2,traditional T1=-6.7,and traditional T2-FLAIR=11.9;and MAGiC T2=7.1,MAGiC T1=-3.9,and MAGiC T2-FLAIR=4.5.CONCLUSION The synthetic MRI vascular screening scheme for patients with acute ischemic stroke can accurately evaluate the degree of bilateral middle cerebral artery stenosis,which is of great significance to early thrombolytic interventional therapy and improving patients’quality of life.展开更多
This paper details on the design of DVB-S2 receivers which is compliant with the broadcasting mode. Special at-tention is paid to the specific receiver functions necessary to demodulate the received signal. To show th...This paper details on the design of DVB-S2 receivers which is compliant with the broadcasting mode. Special at-tention is paid to the specific receiver functions necessary to demodulate the received signal. To show the system performance we consider the design of a complete receiver consisting of timing recovery unit, frame synchronization unit, frequency recovery unit and phase recovery unit. The system is easier to hardware implementation comparing with that provided in (ETSI, 2005; Sun et al., 2004). After the performance of the algorithms is analyzed and a quantitative result is given, this allows us to draw conclusions concerning the achievable system performance under realistic complexity assumptions.展开更多
<div style="text-align:justify;"> Error vector magnitude (EVM) as a performance metric for <em>M</em>-ary quadrature amplitude modulation (QAM) formats in optical coherent systems is presen...<div style="text-align:justify;"> Error vector magnitude (EVM) as a performance metric for <em>M</em>-ary quadrature amplitude modulation (QAM) formats in optical coherent systems is presented. It is shown that the calibrated BER, which would otherwise be under-estimated without the correction factor, can reliably monitor the performance of optical coherent systems near the target BER of 10<sup>-3</sup> for quadrature phase shift keying (QPSK), 16-QAM, and 64-QAM employing carrier phase recovery with differential decoding to compensate for laser phase noise. The impact on the number of symbols used to estimate the BER from EVM analysis is also presented and compared to the BER obtained by error counting. </div>展开更多
Recent studies revealed that the long-lasting daytime ionospheric enhancements of Total Electron Content(TEC)were sometimes observed in the Asian sector during the recovery phase of geomagnetic storms e.g.,Lei(J Geoph...Recent studies revealed that the long-lasting daytime ionospheric enhancements of Total Electron Content(TEC)were sometimes observed in the Asian sector during the recovery phase of geomagnetic storms e.g.,Lei(J Geophys Res Space Phys 123:3217-3232,2018),Li(J Geophys Res Space Phys 125:e2020JA028238,2020).However,they focused only on the dayside ionosphere,and no dedicated studies have been performed to investigate the nighttime ionospheric behavior during such kinds of storm recovery phases.In this study,we focused on two geomagnetic storms that happened on 7-8 September 2017 and 25-26 August 2018,which showed the prominent daytime TEC enhancements in the Asian sector during their recovery phases,to explore the nighttime large-scale ionospheric responses as well as the small-scale Equatorial Plasma Irregularities(EPIs).It is found that during the September 2017 storm recovery phase,the nighttime ionosphere in the American sector is largely depressed,which is similar to the daytime ionospheric response in the same longitude sector;while in the Asian sector,only a small TEC increase is observed at nighttime,which is much weaker than the prominent daytime TEC enhancement in this longitude sector.During the recovery phase of the August 2018 storm,a slight TEC increase is observed on the night side at all longitudes,which is also weaker than the prominent daytime TEC enhancement.For the small-scale EPIs,they are enhanced and extended to higher latitudes during the main phase of both storms.However,during the recovery phases of the first storm,the EPIs are largely enhanced and suppressed in the Asian and American sectors,respectively,while no prominent nighttime EPIs are observed during the second storm recovery phase.The clear north-south asymmetry of equatorial ionization anomaly crests during the second storm should be responsible for the suppression of EPIs during this storm.In addition,our results also suggest that the dusk side ionospheric response could be affected by the daytime ionospheric plasma density/TEC variations during the recovery phase of geomagnetic storms,which further modulates the vertical plasma drift and plasma gradient.As a result,the growth rate of post-sunset EPIs will be enhanced or inhibited.展开更多
Correlation holography uses incoherent light to reconstruct holograms.This technique reconstructs objects as distributions of two-point coherence function rather than using optical fields,as in conventional holography...Correlation holography uses incoherent light to reconstruct holograms.This technique reconstructs objects as distributions of two-point coherence function rather than using optical fields,as in conventional holography.The basic principle of correlation holography is derived from the van Cittert--Zernike theorem and relies on the similarity between the optical field and the coherence functions.Experimental implementation of the correlation holography techniques requires a field or intensity interferometer,and fringe analysis and crosscovariance measurement in these interferometers require a conventional camera with array detectors.With the availability of digitally controlled diffractive elements,it is possible to replace the incoherent light source,such as a rotating ground glass,with a digital source loaded with the random patterns in sequence.Such strategies ease the burden on the detector and allow for correlation holography with a single-pixel detector(SPD)to be used.This review paper discusses a close connection between digital holography and correlation holography.The principles of correlation holography with the SPD are reviewed in detail,and the advantages of using digital sources to mimic incoherent illumination in the correlation holography are examined in the context of three-dimensional and complex field imaging.展开更多
基金supported in part by the Research Grants Council of Hong Kong(Grant Nos.GRF 17201620,GRF 17200321,and RIF R7003-21).
文摘Phase recovery,calculating the phase of a light wave from its intensity measurements,is essential for various applications,such as coherent diffraction imaging,adaptive optics,and biomedical imaging.It enables the reconstruction of an object’s refractive index distribution or topography as well as the correction of imaging system aberrations.In recent years,deep learning has been proven to be highly effective in addressing phase recovery problems.The two most direct deep learning phase recovery strategies are data-driven(DD)with supervised learning mode and physics-driven(PD)with self-supervised learning mode.DD and PD achieve the same goal in different ways yet there is a lack of necessary research to reveal similarities and differences.Therefore,we comprehensively compare these two deep learning phase recovery strategies in terms of time consumption,accuracy,generalization ability,ill-posedness adaptability,and prior capacity.What is more,we propose a co-driven strategy of combining datasets and physics for the balance of high-and low-frequency information.
文摘Background Clinical meaning of recovery phase limited ST segment depression of a treadmill exercise test is controversial.The aim of this study was to re-assess the diagnostic and prognostic value of ST segment depression during the recovery phase with the active phase of a treadmill exercise test in suspected coronary artery disease patients.Methods Clinical,exercise and angiographic data were retrospectively collected from 602 patients in the study.Five hundred and seventy-six patients developed ST segment depression during the active phase of the treadmill exercise test （group 1） and 26 patients developed ST segment depression only during the recovery phase （group 2）.Results With similar major clinical features,the prevalence of significant coronary artery stenosis and average Gensini scores were lower in the recovery phase-limited depression patients （group 2 vs.group 1,50.0% vs.66.9%,P=0.031 and group 2 vs.group 1,1.5 vs.8.5,P=0.04）.At a median follow up of 50.9 months for 22 group 2 and 34.8 months for 438 group 1 patients,the prevalence of total cardiac events was higher in group 1 than in group 2 patients （RR 1.60,95% Cl 1.00-2.54,P=0.049）.Conclusion The present study provides preliminary evidence that the diagnostic and prognostic value of recovery phaselimited ST segment depression of treadmill exercise test is limited.
文摘Severe acute respiratory syndrome (SARS) is an acute respiratory infectious disease caused by a novel coronavirus, firstly broke out in November 2002 in Guangdong and prevailed quickly in Beijing, Hong Kong, Taiwan and other regions of China. It was one of the most potential pandemic diseases and had affected more than 20 other countries.^(1,2) There have been a lot of resear-ches^(2-7) in terms of its etiology, epidemiology, pathogenesis, clinical characteristics, diagnostics, treatment and prevention, vaccines and so on.Along with control of the epidemic situation, a great number of SARS patients were in the recovery phase, therefore, we undertook a half-year follow-up investigation on their clinical, laboratory and image situations.
基金Supported by the National Natural Science foundation of China under Grant No 11474221
文摘The dynamic characteristic of complex network failure and recovery is one of the main research topics in complex networks. Real world systems such as traffic jams and Internet recovery could be described by the complex network theory. We propose a model to study the recovery process in complex networks. Two different recovery mechanisms are considered in three kinds of networks： external recovery and internal recovery. By simulating the process of the nodes recovery in networks, it is found that the system exhibits the feature of first-order phase transition only when the external recovery is considered. Internal recovery cannot induce such a kind of transitions. As external recovery and internal recovery coexist on networks, the systems will retain the most efficient part of external recovery and internal recovery. Meanwhile, a hysteresis could be observed when increasing or decreasing the failure probability. Finally, a largest degree node protection strategy is proposed for improving the robustness of networks.
基金funded by the Life Seedforce(Life20 NAT/IT/001468)。
文摘Salt stress might be an important factor that decreases the emergence of seedlings and reduces plants'growth,causing their endangered status.However,the effects of salt stress on the germination of the Mediterranean species are less concern.Limonium strictissimum(Salzm.)Arrigoni,part of the group related to Limonium articulatum(Loisel.)Kuntze,is a Cyrno-Sardinian endemism,which is included in the International Union for Conservation of Nature(IUCN)Red Lists as Endangered(EN).Fresh seeds of L.strictissimum harvested from the only known population in Sardinia and a population in southeastern Corsica were used with the aims to study the effects of temperature and salinity on the seed germination and to evaluate the ability to recover their germination after exposure to salt stress.In both populations,empty fruits with a lower percentage were observed in Sardinia than in Corsica.The seeds showed a high germination capacity,which was not influenced by temperature and did not even differ between the two populations.Compared with non-saline condition,the presence of salt in the substrate,independently of the concentration tested,inhibited seed germination in both populations,with germination percentages never exceeding 40%.The Sardinian population showed a recovery capacity after exposure to high salt stress,always above 50%regardless of the salt concentration and incubation temperature considered.The seeds previously exposed to 125 mM NaCl at 30℃ had the lowest recovery percentage(56%),while the highest recovery percentage(84%)was recorded at 25℃ with a concentration of 250 mM NaCl.Differently,the Corsican population recorded a higher recovery percentage(54%)in seeds previously exposed to 500 mM NaCl at 20℃,while for the concentration of 125 mM NaCl,the best recovery percentage(11%)was recorded at 30℃.The ability of L.strictissimum to recover germination after salt exposure can be interpreted as an adaptation to the coastal habitats in which it grows.This study provides new insights into the ecophysiology of L.strictissimum seed germination,which could help preserve and implement effective conservation measures for this endangered species with restricted populations.
文摘In this paper,a quadrature phase shift keying(QPSK)phase-recovery algorithm is presented for coherent intersatellite optical wireless communication(Is OWC).From a theoretical perspective,we explain the process of the multiplier-free algorithm.Through simulations,we analyze key parameters and provide guidance on their optimal selection.Additionally,the proposed algorithm maintains stable phase tracking at bit energy to noise power spectral density(Eb/N0)as low as 4 d B.In an ob2b transmission test,our algorithm achieved a sensitivity of-49 d Bm@5 Gbps QPSK[hard-decision forward-errorcorrection(HD-FEC)limit].Compared to the Viterbi and Viterbi phase-recovery(V&V)algorithm,its receiving sensitivity is improved by 1 d B,resulting in a link distance extension of 1100 km.Our multiplier-free and robust algorithm meets the requirements of Is OWC systems and shows promise for future applications.
基金supported by the National Natural Science Foundation of China (60972072)the National Science and Technology Major Projects: the New Generation Broadband Wireless Mobile Communication Network (2009ZX03003-03)the "111 Project" of China (B08038)
文摘An adaptive algorithm named low complexity phase off- set estimation （LC-POE） is proposed for orthogonal frequency division multiplexing （OFDM） signals. Depending on the requirement, the estimation procedure is divided into several scales to accelerate the adaptive convergence speed and ensure the estimation accuracy. The true phase offset is estimated through shrinking the detection range and raising the resolution scale step by step. Both the convergence performance and complexity are discussed in the paper. Simulation results show the effectiveness of the proposed algorithm. The LC-POE algorithm is promising in the application of OFDM systems.
基金Supported by Special Fund of the Technology Division of State Administration of Traditional Chinese Medicine:a Randomized,Double Blinded,Controlled Clinical Trial to Improve the Symptoms of Decreased Digestive Function During the Convalescence of COVID-19(No.2020ZYLCYJ08-5)。
文摘OBJECTIVE:To evaluate the effectiveness and safety of Xiangsha Liujun pills(香砂六君丸) on the decreased digestive function in patients in the recovery phase of the Coronavirus disease 2019(COVID-19).METHODS:A randomized,double blind,placebo controlled clinical trial was conducted.A total of 200 COVID-19 patients in the recovery phase were included in our study in Ezhou Hospital of Traditional Chinese Medicine.Totally 200 subjects were randomly divided into a treatment group(Xiangsha Liujun pills) and a control group(placebo),with 100 in each group.Subjects took Xiangsha Liujun pills or placebo orally three times a day for two weeks.Three visits were scheduled at week 0(baseline),week 1(the middle of the intervention) and week 2(the end of the intervention) for each eligible patient.The total efficacy rates for improving the Traditional Chinese Medicine(TCM) symptoms(fatigue,poor appetite,abdominal distension and loose stools) and the disappearance rates of symptoms were observed and compared in the treatment and control groups.Adverse events were recorded during the study period.SAS 9.4 was used to analyze the data.RESULTS:A total of 200 patients were included in this study,among which 4 participants withdrew because the drugs did not work.Three patients were excluded for age.Before the treatment,there was no significant difference between the TCM symptoms scores of subjects.After 1 week of treatment,the full analysis set(FAS) showed that the efficacy rates for abdominal distension and loose stools in the treatment group were significantly higher than the control group(P < 0.05).There were no significant differences in the efficacy rates for fatigue and poor appetite between the two groups(P > 0.05).In addition,the disappearance rate of fatigue in the treatment group was significantly higher than the control group(P < 0.05);there were no significant differences between the two groups after treatment in the rates of poor appetite,abdominal distension,and loose stools(P > 0.05).After 2 weeks of treatment,the efficacy rates for fatigue,poor appetite,abdominal distension,and loose stools in the treatment group were significantly higher than the control group(P < 0.05).The disappearance rate of loose stools in the treatment group was significantly higher than the control group(P < 0.05).However,there were no significant differences in the disappearance rates of fatigue,poor appetite,and abdominal distension between the two groups(P > 0.05).No severe adverse events were reported by subjects during the study.CONCLUSIONS:This clinical study confirmed that Xiangsha Liujun pills can effectively improve the symptoms related to the decreased digestive function in COVID-19 convalescent patients.
文摘Phase recovery from intensity-only measurements forms the heart of coherent imaging techniques and holography.In this study,we demonstrate that a neural network can learn to perform phase recovery and holographic image reconstruction after appropriate training.This deep learning-based approach provides an entirely new framework to conduct holographic imaging by rapidly eliminating twin-image and self-interference-related spatial artifacts.This neural network-based method is fast to compute and reconstructs phase and amplitude images of the objects using only one hologram,requiring fewer measurements in addition to being computationally faster.We validated this method by reconstructing the phase and amplitude images of various samples,including blood and Pap smears and tissue sections.These results highlight that challenging problems in imaging science can be overcome through machine learning,providing new avenues to design powerful computational imaging systems.
基金Wu Jieping Medical Foundation,No.320.6750.2020-11-22.
文摘BACKGROUND Synthetic magnetic resonance imaging(MRI)MAGnetic resonance imaging compilation(MAGiC)is a new MRI technology.Conventional T1,T2,T2-fluidattenuated inversion recovery(FLAIR)contrast images,quantitative images of T1 and T2 mapping,and MAGiC phase sensitive inversion recovery(PSIR)Vessel cerebrovascular images can be obtained simultaneously through post-processing at the same time after completing a scan.In recent years,studies have reported that MAGiC can be applied to patients with acute ischemic stroke.We hypothesized that the synthetic MRI vascular screening scheme can evaluate the degree of cerebral artery stenosis in patients with acute ischemic stroke.AIM To explore the application value of vascular images obtained by synthetic MRI in diagnosing acute ischemic stroke.METHODS A total of 64 patients with acute ischemic stroke were selected and examined by MRI in the current retrospective cohort study.The scanning sequences included traditional T1,T2,and T2-FLAIR,three-dimensional time-of-flight magnetic resonance angiography(3D TOF MRA),diffusion-weighted imaging(DWI),and synthetic MRI.Conventional contrast images(T1,T2,and T2-FLAIR)and intracranial vessel images(MAGiC PSIR Vessel]were automatically reconstructed using synthetic MRI raw data.The contrast-to-noise ratio(CNR)values of traditional T1,T2,and T2-FLAIR images and MAGiC reconstructed T1,T2,and T2-FLAIR images in DWI diffusion restriction areas were measured and compared.MAGiC PSIR Vessel and TOF MRA images were used to measure and calculate the stenosis degree of bilateral middle cerebral artery stenosis areas.The consistency of MAGiC PSIR Vessel and TOF MRA in displaying the degree of vascular stenosis with computed tomography angiography(CTA)was compared.RESULTS Among the 64 patients with acute ischemic stroke,79 vascular stenosis areas showed that the correlation between MAGiC PSIR Vessel and CTA(r=0.90,P<0.01)was higher than that between TOF MRA and CTA(r=0.84,P<0.01).With a degree of vascular stenosis>50%assessed by CTA as a reference,the area under the receiver operating characteristic(ROC)curve of MAGiC PSIR Vessel[area under the curve(AUC)=0.906,P<0.01]was higher than that of TOF MRA(AUC=0.790,P<0.01).Among the 64 patients with acute ischemic stroke,39 were scanned for traditional T1,T2,and T2-FLAIR images and MAGiC images simultaneously,and CNR values in DWI diffusion restriction areas were measured,which were:Traditional T2=21.2,traditional T1=-6.7,and traditional T2-FLAIR=11.9;and MAGiC T2=7.1,MAGiC T1=-3.9,and MAGiC T2-FLAIR=4.5.CONCLUSION The synthetic MRI vascular screening scheme for patients with acute ischemic stroke can accurately evaluate the degree of bilateral middle cerebral artery stenosis,which is of great significance to early thrombolytic interventional therapy and improving patients’quality of life.
文摘This paper details on the design of DVB-S2 receivers which is compliant with the broadcasting mode. Special at-tention is paid to the specific receiver functions necessary to demodulate the received signal. To show the system performance we consider the design of a complete receiver consisting of timing recovery unit, frame synchronization unit, frequency recovery unit and phase recovery unit. The system is easier to hardware implementation comparing with that provided in (ETSI, 2005; Sun et al., 2004). After the performance of the algorithms is analyzed and a quantitative result is given, this allows us to draw conclusions concerning the achievable system performance under realistic complexity assumptions.
文摘<div style="text-align:justify;"> Error vector magnitude (EVM) as a performance metric for <em>M</em>-ary quadrature amplitude modulation (QAM) formats in optical coherent systems is presented. It is shown that the calibrated BER, which would otherwise be under-estimated without the correction factor, can reliably monitor the performance of optical coherent systems near the target BER of 10<sup>-3</sup> for quadrature phase shift keying (QPSK), 16-QAM, and 64-QAM employing carrier phase recovery with differential decoding to compensate for laser phase noise. The impact on the number of symbols used to estimate the BER from EVM analysis is also presented and compared to the BER obtained by error counting. </div>
基金the National Natural Science Foundation of China(42174191)the start-up program of Wuhan University(600460020)+2 种基金Xin Wan is supported by the China Postdoctoral Science Foundation(2020M683025)Fan Yin is supported by the National Key Research and Development Program of China(Grants 2018YFC1503501-01)the Dragon 5 cooperation 2020-2024(project no.59236)and Chinese Meridian Project.
文摘Recent studies revealed that the long-lasting daytime ionospheric enhancements of Total Electron Content(TEC)were sometimes observed in the Asian sector during the recovery phase of geomagnetic storms e.g.,Lei(J Geophys Res Space Phys 123:3217-3232,2018),Li(J Geophys Res Space Phys 125:e2020JA028238,2020).However,they focused only on the dayside ionosphere,and no dedicated studies have been performed to investigate the nighttime ionospheric behavior during such kinds of storm recovery phases.In this study,we focused on two geomagnetic storms that happened on 7-8 September 2017 and 25-26 August 2018,which showed the prominent daytime TEC enhancements in the Asian sector during their recovery phases,to explore the nighttime large-scale ionospheric responses as well as the small-scale Equatorial Plasma Irregularities(EPIs).It is found that during the September 2017 storm recovery phase,the nighttime ionosphere in the American sector is largely depressed,which is similar to the daytime ionospheric response in the same longitude sector;while in the Asian sector,only a small TEC increase is observed at nighttime,which is much weaker than the prominent daytime TEC enhancement in this longitude sector.During the recovery phase of the August 2018 storm,a slight TEC increase is observed on the night side at all longitudes,which is also weaker than the prominent daytime TEC enhancement.For the small-scale EPIs,they are enhanced and extended to higher latitudes during the main phase of both storms.However,during the recovery phases of the first storm,the EPIs are largely enhanced and suppressed in the Asian and American sectors,respectively,while no prominent nighttime EPIs are observed during the second storm recovery phase.The clear north-south asymmetry of equatorial ionization anomaly crests during the second storm should be responsible for the suppression of EPIs during this storm.In addition,our results also suggest that the dusk side ionospheric response could be affected by the daytime ionospheric plasma density/TEC variations during the recovery phase of geomagnetic storms,which further modulates the vertical plasma drift and plasma gradient.As a result,the growth rate of post-sunset EPIs will be enhanced or inhibited.
基金Science and Engineering Research Board(CORE/2019/000026)Council of Scientific and Industrial Research[No 80(0092)/20/EMR-II]+1 种基金Natural Science Foundation of China(11674111)Fujian Province Science Funds for Distinguished Young Scholar(2018J06017)。
文摘Correlation holography uses incoherent light to reconstruct holograms.This technique reconstructs objects as distributions of two-point coherence function rather than using optical fields,as in conventional holography.The basic principle of correlation holography is derived from the van Cittert--Zernike theorem and relies on the similarity between the optical field and the coherence functions.Experimental implementation of the correlation holography techniques requires a field or intensity interferometer,and fringe analysis and crosscovariance measurement in these interferometers require a conventional camera with array detectors.With the availability of digitally controlled diffractive elements,it is possible to replace the incoherent light source,such as a rotating ground glass,with a digital source loaded with the random patterns in sequence.Such strategies ease the burden on the detector and allow for correlation holography with a single-pixel detector(SPD)to be used.This review paper discusses a close connection between digital holography and correlation holography.The principles of correlation holography with the SPD are reviewed in detail,and the advantages of using digital sources to mimic incoherent illumination in the correlation holography are examined in the context of three-dimensional and complex field imaging.
