AIM:To study the relationships between amplitude of low-frequency fluctuations(ALFF)changes and clinical ophthalmic parameters in patients with primary open angle glaucoma(POAG)and analyze the diagnostic value of ALFF...AIM:To study the relationships between amplitude of low-frequency fluctuations(ALFF)changes and clinical ophthalmic parameters in patients with primary open angle glaucoma(POAG)and analyze the diagnostic value of ALFF.METHODS:Twenty-four POAG patients and 24 healthy controls(HCs)underwent resting-state functional magnetic resonance imaging(rs-fMRI).Nonparametric rank-sum tests were used to compare the ALFF values in the slow-4 and slow-5 bands,and Spearman or Pearson correlation analysis was used to assess the correlation between ALFF changes and clinical ophthalmic parameters in POAG patients.Receiver operating characteristic(ROC)curves were used to evaluate the diagnostic performance of the ALFF.RESULTS:There were 16 males in POAG patients(median age 48y)and 12 males in HCs(median age 39y).Compared with HCs,POAG patients presented increased or decreased ALFF values in different brain regions,and similar changes were observed in mild POAG patients.The ALFF values were correlated with retinal nerve fiber layer(RNFL)thickness,inner limiting membrane-retinal pigment epithelium thickness changes and the degree of visual field defects.Analysis of the diagnostic value of the ALFF via ROC curves revealed that the right medial frontal gyrus[area under the curve(AUC)=0.9063]and superior frontal gyrus(AUC=0.9097)had better diagnostic value than did the optic disc area(AUC=0.8019),visual field index(VFI%,AUC=0.8988)and macular parameters.CONCLUSION:POAG patients present altered cortical function that is significantly correlated with the optic nerve and retinal thickness and had good diagnostic value,which may reflect the underlying neuropathological mechanism of POAG.展开更多
The dynamics of network power response play a crucial role in system stability.However,the integration of power electronic equipment leads to amplitude and angular frequency(abbreviated as"frequency")time-va...The dynamics of network power response play a crucial role in system stability.However,the integration of power electronic equipment leads to amplitude and angular frequency(abbreviated as"frequency")time-varying characteristics of the node voltage during dynamic processes.As a result,traditional calcu-lation methods for and characteristics of the power response of the network based on phasor and impe-dance lose their validity.Therefore,this paper undertakes mathematical calculations to reveal the power response of a network under excitation by voltage with time-varying amplitude and frequency(TVAF),relying on the original mathematical relationships and superimposed step response.Then,the multi-timescale characteristics of both the active and reactive power of the network are explored physically.Additionally,this paper reveals a new phenomenon of storing and releasing the active and reactive power of the network.To meet practical engineering requirements,a simplified power expression is presented.Finally,the theoretical analysis is validated through time-domain simulations.展开更多
This paper designs a high-frequency stable wireless amplitude modulation(AM)system based on a Pierce circuit.The system utilizes an oscillator and comparator to generate a 20 kHz square wave with an adjustable duty cy...This paper designs a high-frequency stable wireless amplitude modulation(AM)system based on a Pierce circuit.The system utilizes an oscillator and comparator to generate a 20 kHz square wave with an adjustable duty cycle,combined with a 41 MHz carrier wave produced by a passive crystal oscillator Pierce circuit.A 100% modulation index amplitude modulation is achieved through the AD835 multiplier.The modulated signal is amplified by a power amplifier circuit and transmitted wirelessly via the transmitter antenna.Upon reception,the signal undergoes two-stage highfrequency amplification before passing through a Schottky diode envelope detector.The NE5532 shaping circuit then restores the square wave.Experimental results demonstrate reliable 11-meter transmission with carrier frequency deviation<0.75% and demodulation error<1%.展开更多
Human motion modeling is a core technology in computer animation,game development,and humancomputer interaction.In particular,generating natural and coherent in-between motion using only the initial and terminal frame...Human motion modeling is a core technology in computer animation,game development,and humancomputer interaction.In particular,generating natural and coherent in-between motion using only the initial and terminal frames remains a fundamental yet unresolved challenge.Existing methods typically rely on dense keyframe inputs or complex prior structures,making it difficult to balance motion quality and plausibility under conditions such as sparse constraints,long-term dependencies,and diverse motion styles.To address this,we propose a motion generation framework based on a frequency-domain diffusion model,which aims to better model complex motion distributions and enhance generation stability under sparse conditions.Our method maps motion sequences to the frequency domain via the Discrete Cosine Transform(DCT),enabling more effective modeling of low-frequency motion structures while suppressing high-frequency noise.A denoising network based on self-attention is introduced to capture long-range temporal dependencies and improve global structural awareness.Additionally,a multi-objective loss function is employed to jointly optimize motion smoothness,pose diversity,and anatomical consistency,enhancing the realism and physical plausibility of the generated sequences.Comparative experiments on the Human3.6M and LaFAN1 datasets demonstrate that our method outperforms state-of-the-art approaches across multiple performance metrics,showing stronger capabilities in generating intermediate motion frames.This research offers a new perspective and methodology for human motion generation and holds promise for applications in character animation,game development,and virtual interaction.展开更多
With the large-scale construction of underground gas storage in salt deposit, much more efforts have been made to assess the fatigue properties of rock salt. The fatigue damage processes the primary, steady,and accele...With the large-scale construction of underground gas storage in salt deposit, much more efforts have been made to assess the fatigue properties of rock salt. The fatigue damage processes the primary, steady,and accelerated phases, which is similar to the axial irrecoverable deformation compiled from the loci of the loading cycles of rock salt. The cumulative fatigue damage increases with a decrease in the loading frequency and with an increase in the stress amplitude within the range tested. To take into account the effects of loading frequency and amplitude on the fatigue behavior of rock salt subjected to cyclic loading, a low cycle fatigue damage model was exclusively established combined with the Manson–Coffin formula. The proposed damage evolution equation was validated with experimental results and proved to be efficient in the prediction of fatigue damage tendency of rock salt under different loading frequencies and amplitudes.展开更多
The 193 nm deep-ultraviolet(DUV)laser plays a critical role in advanced semiconductor chip manufacturing[1,2],micro-nano material characterization[3,4]and biomedical analysis[5,6],due to its high spatial resolution an...The 193 nm deep-ultraviolet(DUV)laser plays a critical role in advanced semiconductor chip manufacturing[1,2],micro-nano material characterization[3,4]and biomedical analysis[5,6],due to its high spatial resolution and short wavelength.Efficient and compact 193 nm DUV laser source thus becomes a hot research area.Currently,193 nm Ar F excimer gas laser is widely employed in DUV lithography systems and serves as the enabling technology for 7 and 5 nm semiconductor fabrication.展开更多
The amplitude of frequency spectrum can he integrated with prohabilisfic data association （PDA） to distinguish the target with clutter echoes, especially in low SNR underwater environment. A new target-tracking algo...The amplitude of frequency spectrum can he integrated with prohabilisfic data association （PDA） to distinguish the target with clutter echoes, especially in low SNR underwater environment. A new target-tracking algorithm is presented which adopts the amplitude of frequency spectrum to improve target tracking in clutter. The prohabilisfic density distribution of frequency spectrum amplitude is analyzed. By simulation, the results show that the algorithm is superior to PDA. This approach enhances stability for the association probability and increases the performance of target tracking.展开更多
Objective:To explore the differences in the central response after acupuncture and moxibusbution at Zusanli(足三里ST36) in treatment of functional dyspepsia(FD) based on the analysis of fractional amplitude of low fre...Objective:To explore the differences in the central response after acupuncture and moxibusbution at Zusanli(足三里ST36) in treatment of functional dyspepsia(FD) based on the analysis of fractional amplitude of low frequency fluctuation(fALFF) of resting-state functional magnetic resonance imaging(rfMRI).Methods:A total of 60 patients with FD were randomized into an acupuncture group and a moxibustion group,30 cases in each one.In the acupuncture group,acupuncture was applied to bilateral ST36.In the moxibustion group,moxibustion was exerted at bilateral ST36.The treatment was given once a day,5 times a week,totally for 4 weeks in each group,including 20 treatments with acupuncture or moxibustion.Separately,before and at the end of treatment,rfMRI scanning was conducted in two groups.Using data processing assistant for resting-state fMRI(DPARSF) software and MATLAB data platform,rfMRI data were collected for preprocessing and fALFF analysis.Results:Compared with the data before treatment,after treated with acupuncture at ST36 in FD patients,fALFF value was reduced in the right superior frontal gyrus,left superior frontal gyrus,left inferior frontal gyrus,right cuneus,left precuneus,right middle occipital gyrus,left middle occipital gyrus,etc.,and it was increased in the left parahippocampus,right parahippocampus,left cerebellum,etc(all P <0.01).After treated with moxibustion,the remarkable increase of fALFF was not discovered in brain areas,but fALFF decreased significantly in the left superior parietal gyrus(P <0.01).Compared with moxibustion at ST36,after acupuncture at ST36 in FD patients,the increase of fALFF appeared in the right putamen and the decrease of it occurred in the middle occipital gyrus,indicating the statistical significance(both P <0.05).Conclusion:The differences in central function responses are induced in treamtent with acupuncture and moxibustion,which is probably related to the resting-state default network associated with targeted regulation and ventral attention of brain areas in functional dyspepsia.展开更多
BACKGROUND Major depressive disorder(MDD)tends to have a high incidence and high suicide risk.Electroconvulsive therapy(ECT)is currently a relatively effective treatment for MDD.However,the mechanism of efficacy of EC...BACKGROUND Major depressive disorder(MDD)tends to have a high incidence and high suicide risk.Electroconvulsive therapy(ECT)is currently a relatively effective treatment for MDD.However,the mechanism of efficacy of ECT is still unclear.AIM To investigate the changes in the amplitude of low-frequency fluctuations in specific frequency bands in patients with MDD after ECT.METHODS Twenty-two MDD patients and fifteen healthy controls(HCs)were recruited to this study.MDD patients received 8 ECT sessions with bitemporal placement.Resting-state functional magnetic resonance imaging was adopted to examine regional cerebellar blood flow in both the MDD patients and HCs.The MDD patients were scanned twice(before the first ECT session and after the eighth ECT session)to acquire data.Then,the amplitude of low-frequency fluctuations(ALFF)was computed to characterize the intrinsic neural oscillations in different bands(typical frequency,slow-5,and slow-4 bands).RESULTS Compared to before ECT(pre-ECT),we found that MDD patients after the eighth ECT(post-ECT)session had a higher ALFF in the typical band in the right middle frontal gyrus,posterior cingulate,right supramarginal gyrus,left superior frontal gyrus,and left angular gyrus.There was a lower ALFF in the right superior temporal gyrus.Compared to pre-ECT values,the ALFF in the slow-5 band was significantly increased in the right limbic lobe,cerebellum posterior lobe,right middle orbitofrontal gyrus,and frontal lobe in post-ECT patients,whereas the ALFF in the slow-5 band in the left sublobar region,right angular gyrus,and right frontal lobe was lower.In contrast,significantly higher ALFF in the slow-4 band was observed in the frontal lobe,superior frontal gyrus,parietal lobe,right inferior parietal lobule,and left angular gyrus.CONCLUSION Our results suggest that the abnormal ALFF in pre-and post-ECT MDD patients may be associated with specific frequency bands.展开更多
In the past century, there have been many attempts to treat cancer with low levels of electric and magnetic fields. We have developed noninvasive biofeedback examination devices and techniques and discovered that pati...In the past century, there have been many attempts to treat cancer with low levels of electric and magnetic fields. We have developed noninvasive biofeedback examination devices and techniques and discovered that patients with the same tumor type exhibit biofeedback responses to the same, precise frequencies. Intrabuccal administration of 27.12 MHz radiofrequency(RF) electromagnetic fields(EMF), which are amplitude-modulated at tumor-specific frequencies, results in long-term objective responses in patients with cancer and is not associated with any significant adverse effects. Intrabuccal administration allows for therapeutic delivery of very low and safe levels of EMF throughout the body as exemplified by responses observed in the femur, liver, adrenal glands, and lungs. In vitro studies have demonstrated that tumor-specific frequencies identified in patients with various forms of cancer are capable of blocking the growth of tumor cells in a tissue- and tumor-specific fashion. Current experimental evidence suggests that tumor-specific modulation frequencies regulate the expression of genes involved in migration and invasion and disrupt the mitotic spindle. This novel targeted treatment approach is emerging as an appealing therapeutic option for patients with advanced cancer given its excellent tolerability. Dissection of the molecular mechanisms accounting for the anti-cancer effects of tumor-specific modulation frequencies is likely to lead to the discovery of novel pathways in cancer.展开更多
BACKGROUND Diabetes mellitus is a metabolic disorder characterized by prolonged elevation of blood glucose due to various causes.Currently,the relationship between diabetic retinopathy(DR)and altered connectivity of b...BACKGROUND Diabetes mellitus is a metabolic disorder characterized by prolonged elevation of blood glucose due to various causes.Currently,the relationship between diabetic retinopathy(DR)and altered connectivity of brain function is unclear.AIM To investigate the relationship between this brain activity and clinical manifestations and behaviors of DR patients by using the amplitude of low-frequency fluctuation(ALFF)technique.METHODS Twenty-four DR patients and 24 healthy controls(HCs)matched for age and gender were enrolled.We measured and recorded average ALFF values of DR patients and HCs and then classified them using receiver operating characteristic(ROC)curves.RESULTS ALFF values of both left and right posterior cerebellar lobe and right anterior cingulate gyrus were remarkably higher in the DR patients than in the HCs;however,DR patients had lower values in the bilateral calcarine area.ROC curve analysis of different brain regions demonstrated high accuracy in the area under the curve analysis.There was no significant relationship between mean ALFF values for different regions and clinical presentations in DR patients.Neuronal synchronization abnormalities in some brain regions of DR patients were associated with cognitive and visual disorders.CONCLUSION Abnormal spontaneous brain activity was observed in many areas of DR patients’brains,which may suggest a possible link between clinical manifestations and behaviors in DR patients.展开更多
AIM:To analyze changes in amplitude of low-frequency fluctuations(ALFFs)and default mode network(DMN)connectivity in the brain,using resting-state functional magnetic resonance imaging(rs-fMRI),in high myopia(HM)patie...AIM:To analyze changes in amplitude of low-frequency fluctuations(ALFFs)and default mode network(DMN)connectivity in the brain,using resting-state functional magnetic resonance imaging(rs-fMRI),in high myopia(HM)patients.METHODS:Eleven patients with HM(HM group)and 15 age-and sex-matched non-HM controls(non-HM group)were recruited.ALFFs were calculated and compared between HM group and non-HM group.Independent component analysis(ICA)was conducted to identify DMN,and comparisons between DMNs of two groups were performed.Region-of-interest(ROI)-based analysis was performed to explore functional connectivity(FC)between DMN regions.RESULTS:Significantly increased ALFFs in left inferior temporal gyrus(ITG),bilateral rectus gyrus(REC),bilateral middle temporal gyrus(MTG),left superior temporal gyrus(STG),and left angular gyrus(ANG)were detected in HM group compared with non-HM group(all P<0.01).HM group showed increased FC in the posterior cingulate gyrus(PCC)/precuneus(preCUN)and decreased FC in the left medial prefrontal cortex(mPFG)within DMN compared with nonHM group(all P<0.01).Compared with non-HM group,HM group showed higher FC between mPFG and bilateral middle frontal gyrus(MFG),ANG,and MTG(all P<0.01).In addition,HM patients showed higher FC between PCC/(preCUN)and the right cerebellum,superior frontal gyrus(SFG),left pre CUN,superior frontal gyrus(SFG),and medial orbital of the superior frontal gyrus(ORB supmed;all P<0.01).CONCLUSION:HM patients show different ALFFs and DMNs compared with non-HM subjects,which may imply the cognitive alterations related to HM.展开更多
To estimate the motion parameters of a moving target before its passing by the closest point of approach （CPA） point in a low frequency analyzing and recording （LOFAR） field, an error-free theoretical method based...To estimate the motion parameters of a moving target before its passing by the closest point of approach （CPA） point in a low frequency analyzing and recording （LOFAR） field, an error-free theoretical method based on the joint measurement of target radiated noise＇s amplitude and frequency was presented. First, the error-free theoretical equations for target characteristic frequency, absolute velocity, the CPA, and amplitude of the radiation noise were derived by three equal interval measured values of the target amplitude and frequency. Then, the method to improve the calculation accuracy was given. Finally, the simulation and experiments were conducted in the air and showed the correctness of this method. By using one single piece of LOFAR, this method can calculate four target parameters and the relative error of each estimated parameter is less than 10%.展开更多
It is now well known that amplitude modulated(AM) high frequency(HF) radio wave transmissions into the ionosphere can be used to generate very/extremely low frequency(VLF/ELF) radio waves using the so-called ‘electro...It is now well known that amplitude modulated(AM) high frequency(HF) radio wave transmissions into the ionosphere can be used to generate very/extremely low frequency(VLF/ELF) radio waves using the so-called ‘electrojet antenna’. Duty cycle and heating frequency are analyzed and discussed with the lower-ionosphere modulated heating model, so as to improve the radiation efficiency of VLF/ELF waves in AM ionospheric heating experiments. Based on numerical simulation, the ranges of parametric selectivity in optimal duty cycle and heating frequency( fHF) are derived. The International Reference Ionosphere 2015(IRI-2015) model and two-parameter model are used to predict background electron density profiles, and optimized ranges of duty cycle for different density profiles are analyzed and compared. The influences of wave polarizations on optimal duty cycle are also discussed. It is shown that intensity of the VLF/ELF equivalent radiation source(M) firstly rises and then falls with the increase of duty cycle. When using the IRI model, M peaks at a duty cycle of 50%, optimally ranging from 40%-70%. For the two-parameter model case, an optimal duty cycle is 40% and the optimized ranges vary from 30%-60%. Heating with an X-mode polarization is more efficient than with the O-mode case in VLF/ELF wave generation. Nevertheless, an optimal duty cycle is almost independent of HF wave polarizations. To obtain better VLF/ELF generation, optional fHFmay be 0.8-0.9 times of foE for the O-mode heating and 0.75-0.85 times for the X-mode polarization case. Finally, the variations of these two parameters in different latitudes are discussed.展开更多
Although some short-term follow-up studies have found that individuals recovering from coronavirus disease 2019(COVID-19)exhibit anxiety,depression,and altered brain microstructure,their long-term physical problems,ne...Although some short-term follow-up studies have found that individuals recovering from coronavirus disease 2019(COVID-19)exhibit anxiety,depression,and altered brain microstructure,their long-term physical problems,neuropsychiatric sequelae,and changes in brain function remain unknown.This observational cohort study collected 1-year follow-up data from 22 patients who had been hospitalized with COVID-19(8 males and 11 females,aged 54.2±8.7 years).Fatigue and myalgia were persistent symptoms at the 1-year follow-up.The resting state functional magnetic resonance imaging revealed that compared with 29 healthy controls(7 males and 18 females,aged 50.5±11.6 years),COVID-19 survivors had greatly increased amplitude of low-frequency fluctuation(ALFF)values in the left precentral gyrus,middle frontal gyrus,inferior frontal gyrus of operculum,inferior frontal gyrus of triangle,insula,hippocampus,parahippocampal gyrus,fusiform gyrus,postcentral gyrus,inferior parietal angular gyrus,supramarginal gyrus,angular gyrus,thalamus,middle temporal gyrus,inferior temporal gyrus,caudate,and putamen.ALFF values in the left caudate of the COVID-19 survivors were positively correlated with their Athens Insomnia Scale scores,and those in the left precentral gyrus were positively correlated with neutrophil count during hospitalization.The long-term follow-up results suggest that the ALFF in brain regions related to mood and sleep regulation were altered in COVID-19 survivors.This can help us understand the neurobiological mechanisms of COVID-19-related neuropsychiatric sequelae.This study was approved by the Ethics Committee of the Second Xiangya Hospital of Central South University(approval No.2020 S004)on March 19,2020.展开更多
In the torsion pendulum experiments, the thermal noise sets the most fundamental limit to the accurate estimation of the amplitude of the signal with known frequency. The variance of the conventional method can meet t...In the torsion pendulum experiments, the thermal noise sets the most fundamental limit to the accurate estimation of the amplitude of the signal with known frequency. The variance of the conventional method can meet the limit only when the measurement time is much longer than the relaxation time of the pendulum. By using the maximum likelihood estimation and the equation-of-motion filter operator, we propose an optimal(minimum variance, unbiased) amplitude estimation method without limitation of the measurement time, where thermal fluctuation is the leading noise. While processing the experimental data tests of the Newtonian gravitational inverse square law, the variance of our method has been improved than before and the measurement time of determining the amplitude with this method has been reduced about half than before for the same uncertainty. These results are significant for the torsion experiment when the measurement time is limited.展开更多
The parametric instability behavior of a liquid mercury sessile drop under high frequency Amplitude-Modulate Magnetic Field(AMMF),i.e.a high frequency magnetic field(carder wave)modulated by a low frequency sine wave(...The parametric instability behavior of a liquid mercury sessile drop under high frequency Amplitude-Modulate Magnetic Field(AMMF),i.e.a high frequency magnetic field(carder wave)modulated by a low frequency sine wave(modulate wave),is investigated experimentally.The free surface contour of the mercury drop is observed by a CCD camera while varying the frequency and amplitude of the high frequency AMMF.At a given frequency and amplitude,the edge deformations with an azimuthal wave numbers(modes n=3,4,5,6)were excited.展开更多
Although stimulus frequency otoacoustic emissions (SFOAEs) have been used as a non-invasive measure of cochlear mechanics, clinical and experimental application of SFOAEs has been limited by difficulties in accurately...Although stimulus frequency otoacoustic emissions (SFOAEs) have been used as a non-invasive measure of cochlear mechanics, clinical and experimental application of SFOAEs has been limited by difficulties in accurately deriving quantitative information from sound pressure measured in the ear canal. In this study, a novel signal processing method for multicomponent analysis (MCA) was used to measure the amplitude and delay of the SFOAE. This report shows the delay-frequency distribution of the SFOAE measured from the human ear. A low level acoustical suppressor near the probe tone significantly suppressed the SFOAE, strongly indicating that the SFOAE was generated at characteristic frequency locations. Information derived from this method may reveal more details of cochlear mechanics in the human ear.展开更多
Amplitude quantization is one of the main sources of spurious noise frequencies in Direct Digital Frequency Synthesizers (DDFSs), which affect their application to many wireless telecommu- nication systems. In this pa...Amplitude quantization is one of the main sources of spurious noise frequencies in Direct Digital Frequency Synthesizers (DDFSs), which affect their application to many wireless telecommu- nication systems. In this paper, two different kinds of spurious signals due to amplitude quantization in DDFSs are exactly formulated in the time domain and detailedly compared in the frequency do- main, and the effects of the DDFS parameter variations on the spurious performance are thoroughly studied. Then the spectral properties and power levels of the amplitude-quantization spurs in the absence of phase-accumulator truncation are emphatically analyzed by waveform estimation and computer simulation, and several important conclusions are derived which can provide theoretical support for parameter choice and spurious performance evaluation in the application of DDFSs.展开更多
Satellite vibrations during exposure will lead to pixel aliasing of remote sensors, resulting in the deterioration of image quality. In this paper, we expose the problem and discuss the characteristics of satellite vi...Satellite vibrations during exposure will lead to pixel aliasing of remote sensors, resulting in the deterioration of image quality. In this paper, we expose the problem and discuss the characteristics of satellite vibrations, and then present a pixel mixing model. The idea of mean mixing ratio （MMR） is proposed. MMR computations for different frequencies are implemented. In the mixing model, a coefficient matrix is introduced to estimate each mixed pixel. Thus, the simulation of degraded image can be performed when the vibration attitudes are known. The computation of MMR takes into considera- tion the influences of various frequencies and amplitudes. Therefore, the roles of these parameters played in the degradation progress are identified. Computations show that under the same vibration amplitude, the influence of vibrations fluctuates with the variation of frequency. The fluctuation becomes smaller as the frequency rises. Two kinds of vibration imaging experiments are performed： different amplitudes with the same frequency and different frequencies with the same amplitude. Results are found to be in very good agreement with the theoretical results. MMR has a better description of image quality than modulation transfer function （MTF）. The influence of vibrations is determined mainly by the amplitude rather than the frequency. The influence of vibrations on image quality becomes gradually stable with the increase of frequency.展开更多
基金Supported by National Natural Science Foundation of China(No.82260203).
文摘AIM:To study the relationships between amplitude of low-frequency fluctuations(ALFF)changes and clinical ophthalmic parameters in patients with primary open angle glaucoma(POAG)and analyze the diagnostic value of ALFF.METHODS:Twenty-four POAG patients and 24 healthy controls(HCs)underwent resting-state functional magnetic resonance imaging(rs-fMRI).Nonparametric rank-sum tests were used to compare the ALFF values in the slow-4 and slow-5 bands,and Spearman or Pearson correlation analysis was used to assess the correlation between ALFF changes and clinical ophthalmic parameters in POAG patients.Receiver operating characteristic(ROC)curves were used to evaluate the diagnostic performance of the ALFF.RESULTS:There were 16 males in POAG patients(median age 48y)and 12 males in HCs(median age 39y).Compared with HCs,POAG patients presented increased or decreased ALFF values in different brain regions,and similar changes were observed in mild POAG patients.The ALFF values were correlated with retinal nerve fiber layer(RNFL)thickness,inner limiting membrane-retinal pigment epithelium thickness changes and the degree of visual field defects.Analysis of the diagnostic value of the ALFF via ROC curves revealed that the right medial frontal gyrus[area under the curve(AUC)=0.9063]and superior frontal gyrus(AUC=0.9097)had better diagnostic value than did the optic disc area(AUC=0.8019),visual field index(VFI%,AUC=0.8988)and macular parameters.CONCLUSION:POAG patients present altered cortical function that is significantly correlated with the optic nerve and retinal thickness and had good diagnostic value,which may reflect the underlying neuropathological mechanism of POAG.
基金supported in part by the National Natural Science Fundation of China(52225704 and 52107096).
文摘The dynamics of network power response play a crucial role in system stability.However,the integration of power electronic equipment leads to amplitude and angular frequency(abbreviated as"frequency")time-varying characteristics of the node voltage during dynamic processes.As a result,traditional calcu-lation methods for and characteristics of the power response of the network based on phasor and impe-dance lose their validity.Therefore,this paper undertakes mathematical calculations to reveal the power response of a network under excitation by voltage with time-varying amplitude and frequency(TVAF),relying on the original mathematical relationships and superimposed step response.Then,the multi-timescale characteristics of both the active and reactive power of the network are explored physically.Additionally,this paper reveals a new phenomenon of storing and releasing the active and reactive power of the network.To meet practical engineering requirements,a simplified power expression is presented.Finally,the theoretical analysis is validated through time-domain simulations.
文摘This paper designs a high-frequency stable wireless amplitude modulation(AM)system based on a Pierce circuit.The system utilizes an oscillator and comparator to generate a 20 kHz square wave with an adjustable duty cycle,combined with a 41 MHz carrier wave produced by a passive crystal oscillator Pierce circuit.A 100% modulation index amplitude modulation is achieved through the AD835 multiplier.The modulated signal is amplified by a power amplifier circuit and transmitted wirelessly via the transmitter antenna.Upon reception,the signal undergoes two-stage highfrequency amplification before passing through a Schottky diode envelope detector.The NE5532 shaping circuit then restores the square wave.Experimental results demonstrate reliable 11-meter transmission with carrier frequency deviation<0.75% and demodulation error<1%.
基金supported by the National Natural Science Foundation of China(Grant No.72161034).
文摘Human motion modeling is a core technology in computer animation,game development,and humancomputer interaction.In particular,generating natural and coherent in-between motion using only the initial and terminal frames remains a fundamental yet unresolved challenge.Existing methods typically rely on dense keyframe inputs or complex prior structures,making it difficult to balance motion quality and plausibility under conditions such as sparse constraints,long-term dependencies,and diverse motion styles.To address this,we propose a motion generation framework based on a frequency-domain diffusion model,which aims to better model complex motion distributions and enhance generation stability under sparse conditions.Our method maps motion sequences to the frequency domain via the Discrete Cosine Transform(DCT),enabling more effective modeling of low-frequency motion structures while suppressing high-frequency noise.A denoising network based on self-attention is introduced to capture long-range temporal dependencies and improve global structural awareness.Additionally,a multi-objective loss function is employed to jointly optimize motion smoothness,pose diversity,and anatomical consistency,enhancing the realism and physical plausibility of the generated sequences.Comparative experiments on the Human3.6M and LaFAN1 datasets demonstrate that our method outperforms state-of-the-art approaches across multiple performance metrics,showing stronger capabilities in generating intermediate motion frames.This research offers a new perspective and methodology for human motion generation and holds promise for applications in character animation,game development,and virtual interaction.
基金fundings and supports of the National Basic Research Program of China (No. 2013CB036005)the National Natural Science Foundation of China (Nos. 51309234, 51527810, 51304219, and 51021001)+2 种基金the Natural Science Foundation of Jiangsu Province of China (No. BK20130065)the Open Foundation of State Key Laboratory for Geomechanics and Deep Underground Engineering of China (No. SKLGDUEK1403)the China Postdoctoral Science Foundation (No. 2015M570451)
文摘With the large-scale construction of underground gas storage in salt deposit, much more efforts have been made to assess the fatigue properties of rock salt. The fatigue damage processes the primary, steady,and accelerated phases, which is similar to the axial irrecoverable deformation compiled from the loci of the loading cycles of rock salt. The cumulative fatigue damage increases with a decrease in the loading frequency and with an increase in the stress amplitude within the range tested. To take into account the effects of loading frequency and amplitude on the fatigue behavior of rock salt subjected to cyclic loading, a low cycle fatigue damage model was exclusively established combined with the Manson–Coffin formula. The proposed damage evolution equation was validated with experimental results and proved to be efficient in the prediction of fatigue damage tendency of rock salt under different loading frequencies and amplitudes.
基金supported by the National Natural Science Foundation of China(Grant Nos.62450006,62304217,62274157,62127807,62234011,62034008,62074142,62074140)Tianshan Innovation Team Program(Grant No.2022TSYCTD0005)+1 种基金Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB0880000)Youth Innovation Promotion Association of the Chinese Academy of Sciences(Grant Nos.2023124,Y2023032)。
文摘The 193 nm deep-ultraviolet(DUV)laser plays a critical role in advanced semiconductor chip manufacturing[1,2],micro-nano material characterization[3,4]and biomedical analysis[5,6],due to its high spatial resolution and short wavelength.Efficient and compact 193 nm DUV laser source thus becomes a hot research area.Currently,193 nm Ar F excimer gas laser is widely employed in DUV lithography systems and serves as the enabling technology for 7 and 5 nm semiconductor fabrication.
基金This project was supported by the Defense Pre-Research Project of the‘Tenth Five-Year-Plan’of China (40105010101)
文摘The amplitude of frequency spectrum can he integrated with prohabilisfic data association （PDA） to distinguish the target with clutter echoes, especially in low SNR underwater environment. A new target-tracking algorithm is presented which adopts the amplitude of frequency spectrum to improve target tracking in clutter. The prohabilisfic density distribution of frequency spectrum amplitude is analyzed. By simulation, the results show that the algorithm is superior to PDA. This approach enhances stability for the association probability and increases the performance of target tracking.
基金Supported by Changsha Outstanding Innovation Youth Training Project:kq1905036Open Fund Project of First-Class Discipline in Traditional Chinese Medicine of Hunan University of Chinese Medicine:2018ZYX04。
文摘Objective:To explore the differences in the central response after acupuncture and moxibusbution at Zusanli(足三里ST36) in treatment of functional dyspepsia(FD) based on the analysis of fractional amplitude of low frequency fluctuation(fALFF) of resting-state functional magnetic resonance imaging(rfMRI).Methods:A total of 60 patients with FD were randomized into an acupuncture group and a moxibustion group,30 cases in each one.In the acupuncture group,acupuncture was applied to bilateral ST36.In the moxibustion group,moxibustion was exerted at bilateral ST36.The treatment was given once a day,5 times a week,totally for 4 weeks in each group,including 20 treatments with acupuncture or moxibustion.Separately,before and at the end of treatment,rfMRI scanning was conducted in two groups.Using data processing assistant for resting-state fMRI(DPARSF) software and MATLAB data platform,rfMRI data were collected for preprocessing and fALFF analysis.Results:Compared with the data before treatment,after treated with acupuncture at ST36 in FD patients,fALFF value was reduced in the right superior frontal gyrus,left superior frontal gyrus,left inferior frontal gyrus,right cuneus,left precuneus,right middle occipital gyrus,left middle occipital gyrus,etc.,and it was increased in the left parahippocampus,right parahippocampus,left cerebellum,etc(all P <0.01).After treated with moxibustion,the remarkable increase of fALFF was not discovered in brain areas,but fALFF decreased significantly in the left superior parietal gyrus(P <0.01).Compared with moxibustion at ST36,after acupuncture at ST36 in FD patients,the increase of fALFF appeared in the right putamen and the decrease of it occurred in the middle occipital gyrus,indicating the statistical significance(both P <0.05).Conclusion:The differences in central function responses are induced in treamtent with acupuncture and moxibustion,which is probably related to the resting-state default network associated with targeted regulation and ventral attention of brain areas in functional dyspepsia.
基金Supported by the Natural Science Foundation of China,No.81901373the Intelligent Medicine Research Project of Chongqing Medical University,No.ZHYX202126.
文摘BACKGROUND Major depressive disorder(MDD)tends to have a high incidence and high suicide risk.Electroconvulsive therapy(ECT)is currently a relatively effective treatment for MDD.However,the mechanism of efficacy of ECT is still unclear.AIM To investigate the changes in the amplitude of low-frequency fluctuations in specific frequency bands in patients with MDD after ECT.METHODS Twenty-two MDD patients and fifteen healthy controls(HCs)were recruited to this study.MDD patients received 8 ECT sessions with bitemporal placement.Resting-state functional magnetic resonance imaging was adopted to examine regional cerebellar blood flow in both the MDD patients and HCs.The MDD patients were scanned twice(before the first ECT session and after the eighth ECT session)to acquire data.Then,the amplitude of low-frequency fluctuations(ALFF)was computed to characterize the intrinsic neural oscillations in different bands(typical frequency,slow-5,and slow-4 bands).RESULTS Compared to before ECT(pre-ECT),we found that MDD patients after the eighth ECT(post-ECT)session had a higher ALFF in the typical band in the right middle frontal gyrus,posterior cingulate,right supramarginal gyrus,left superior frontal gyrus,and left angular gyrus.There was a lower ALFF in the right superior temporal gyrus.Compared to pre-ECT values,the ALFF in the slow-5 band was significantly increased in the right limbic lobe,cerebellum posterior lobe,right middle orbitofrontal gyrus,and frontal lobe in post-ECT patients,whereas the ALFF in the slow-5 band in the left sublobar region,right angular gyrus,and right frontal lobe was lower.In contrast,significantly higher ALFF in the slow-4 band was observed in the frontal lobe,superior frontal gyrus,parietal lobe,right inferior parietal lobule,and left angular gyrus.CONCLUSION Our results suggest that the abnormal ALFF in pre-and post-ECT MDD patients may be associated with specific frequency bands.
文摘In the past century, there have been many attempts to treat cancer with low levels of electric and magnetic fields. We have developed noninvasive biofeedback examination devices and techniques and discovered that patients with the same tumor type exhibit biofeedback responses to the same, precise frequencies. Intrabuccal administration of 27.12 MHz radiofrequency(RF) electromagnetic fields(EMF), which are amplitude-modulated at tumor-specific frequencies, results in long-term objective responses in patients with cancer and is not associated with any significant adverse effects. Intrabuccal administration allows for therapeutic delivery of very low and safe levels of EMF throughout the body as exemplified by responses observed in the femur, liver, adrenal glands, and lungs. In vitro studies have demonstrated that tumor-specific frequencies identified in patients with various forms of cancer are capable of blocking the growth of tumor cells in a tissue- and tumor-specific fashion. Current experimental evidence suggests that tumor-specific modulation frequencies regulate the expression of genes involved in migration and invasion and disrupt the mitotic spindle. This novel targeted treatment approach is emerging as an appealing therapeutic option for patients with advanced cancer given its excellent tolerability. Dissection of the molecular mechanisms accounting for the anti-cancer effects of tumor-specific modulation frequencies is likely to lead to the discovery of novel pathways in cancer.
文摘BACKGROUND Diabetes mellitus is a metabolic disorder characterized by prolonged elevation of blood glucose due to various causes.Currently,the relationship between diabetic retinopathy(DR)and altered connectivity of brain function is unclear.AIM To investigate the relationship between this brain activity and clinical manifestations and behaviors of DR patients by using the amplitude of low-frequency fluctuation(ALFF)technique.METHODS Twenty-four DR patients and 24 healthy controls(HCs)matched for age and gender were enrolled.We measured and recorded average ALFF values of DR patients and HCs and then classified them using receiver operating characteristic(ROC)curves.RESULTS ALFF values of both left and right posterior cerebellar lobe and right anterior cingulate gyrus were remarkably higher in the DR patients than in the HCs;however,DR patients had lower values in the bilateral calcarine area.ROC curve analysis of different brain regions demonstrated high accuracy in the area under the curve analysis.There was no significant relationship between mean ALFF values for different regions and clinical presentations in DR patients.Neuronal synchronization abnormalities in some brain regions of DR patients were associated with cognitive and visual disorders.CONCLUSION Abnormal spontaneous brain activity was observed in many areas of DR patients’brains,which may suggest a possible link between clinical manifestations and behaviors in DR patients.
基金Supported by the National Natural Science Foundation of China(No.81870685)Beijing Natural Science Foundation(No.7172173)Key Laboratory of Myopia,Ministry of Health(Fudan University)(No.EENTM-15-01)。
文摘AIM:To analyze changes in amplitude of low-frequency fluctuations(ALFFs)and default mode network(DMN)connectivity in the brain,using resting-state functional magnetic resonance imaging(rs-fMRI),in high myopia(HM)patients.METHODS:Eleven patients with HM(HM group)and 15 age-and sex-matched non-HM controls(non-HM group)were recruited.ALFFs were calculated and compared between HM group and non-HM group.Independent component analysis(ICA)was conducted to identify DMN,and comparisons between DMNs of two groups were performed.Region-of-interest(ROI)-based analysis was performed to explore functional connectivity(FC)between DMN regions.RESULTS:Significantly increased ALFFs in left inferior temporal gyrus(ITG),bilateral rectus gyrus(REC),bilateral middle temporal gyrus(MTG),left superior temporal gyrus(STG),and left angular gyrus(ANG)were detected in HM group compared with non-HM group(all P<0.01).HM group showed increased FC in the posterior cingulate gyrus(PCC)/precuneus(preCUN)and decreased FC in the left medial prefrontal cortex(mPFG)within DMN compared with nonHM group(all P<0.01).Compared with non-HM group,HM group showed higher FC between mPFG and bilateral middle frontal gyrus(MFG),ANG,and MTG(all P<0.01).In addition,HM patients showed higher FC between PCC/(preCUN)and the right cerebellum,superior frontal gyrus(SFG),left pre CUN,superior frontal gyrus(SFG),and medial orbital of the superior frontal gyrus(ORB supmed;all P<0.01).CONCLUSION:HM patients show different ALFFs and DMNs compared with non-HM subjects,which may imply the cognitive alterations related to HM.
基金Project supported by the National Natural Science Foundation of China （No. 51209173）
文摘To estimate the motion parameters of a moving target before its passing by the closest point of approach （CPA） point in a low frequency analyzing and recording （LOFAR） field, an error-free theoretical method based on the joint measurement of target radiated noise＇s amplitude and frequency was presented. First, the error-free theoretical equations for target characteristic frequency, absolute velocity, the CPA, and amplitude of the radiation noise were derived by three equal interval measured values of the target amplitude and frequency. Then, the method to improve the calculation accuracy was given. Finally, the simulation and experiments were conducted in the air and showed the correctness of this method. By using one single piece of LOFAR, this method can calculate four target parameters and the relative error of each estimated parameter is less than 10%.
基金supported by the Innovation Fund of China Electronics Technology Group Corporation (No. KJ1602004)
文摘It is now well known that amplitude modulated(AM) high frequency(HF) radio wave transmissions into the ionosphere can be used to generate very/extremely low frequency(VLF/ELF) radio waves using the so-called ‘electrojet antenna’. Duty cycle and heating frequency are analyzed and discussed with the lower-ionosphere modulated heating model, so as to improve the radiation efficiency of VLF/ELF waves in AM ionospheric heating experiments. Based on numerical simulation, the ranges of parametric selectivity in optimal duty cycle and heating frequency( fHF) are derived. The International Reference Ionosphere 2015(IRI-2015) model and two-parameter model are used to predict background electron density profiles, and optimized ranges of duty cycle for different density profiles are analyzed and compared. The influences of wave polarizations on optimal duty cycle are also discussed. It is shown that intensity of the VLF/ELF equivalent radiation source(M) firstly rises and then falls with the increase of duty cycle. When using the IRI model, M peaks at a duty cycle of 50%, optimally ranging from 40%-70%. For the two-parameter model case, an optimal duty cycle is 40% and the optimized ranges vary from 30%-60%. Heating with an X-mode polarization is more efficient than with the O-mode case in VLF/ELF wave generation. Nevertheless, an optimal duty cycle is almost independent of HF wave polarizations. To obtain better VLF/ELF generation, optional fHFmay be 0.8-0.9 times of foE for the O-mode heating and 0.75-0.85 times for the X-mode polarization case. Finally, the variations of these two parameters in different latitudes are discussed.
基金supported by Key Emergency Project of Pneumonia Epidemic of Novel Coronavirus Infection of China,No.2020SK3006(to JL)Clinical Research Center for Medical Imaging in Hunan Province of China,No.2020SK4001(to JL)the Innovative Major Emergency Project Funding against the New Coronavirus Pneumonia in Hunan Province of China,No.2020SK3014(to JYL)。
文摘Although some short-term follow-up studies have found that individuals recovering from coronavirus disease 2019(COVID-19)exhibit anxiety,depression,and altered brain microstructure,their long-term physical problems,neuropsychiatric sequelae,and changes in brain function remain unknown.This observational cohort study collected 1-year follow-up data from 22 patients who had been hospitalized with COVID-19(8 males and 11 females,aged 54.2±8.7 years).Fatigue and myalgia were persistent symptoms at the 1-year follow-up.The resting state functional magnetic resonance imaging revealed that compared with 29 healthy controls(7 males and 18 females,aged 50.5±11.6 years),COVID-19 survivors had greatly increased amplitude of low-frequency fluctuation(ALFF)values in the left precentral gyrus,middle frontal gyrus,inferior frontal gyrus of operculum,inferior frontal gyrus of triangle,insula,hippocampus,parahippocampal gyrus,fusiform gyrus,postcentral gyrus,inferior parietal angular gyrus,supramarginal gyrus,angular gyrus,thalamus,middle temporal gyrus,inferior temporal gyrus,caudate,and putamen.ALFF values in the left caudate of the COVID-19 survivors were positively correlated with their Athens Insomnia Scale scores,and those in the left precentral gyrus were positively correlated with neutrophil count during hospitalization.The long-term follow-up results suggest that the ALFF in brain regions related to mood and sleep regulation were altered in COVID-19 survivors.This can help us understand the neurobiological mechanisms of COVID-19-related neuropsychiatric sequelae.This study was approved by the Ethics Committee of the Second Xiangya Hospital of Central South University(approval No.2020 S004)on March 19,2020.
基金Project supported by the National Natural Science Foundation of China(Grant No.11575160)
文摘In the torsion pendulum experiments, the thermal noise sets the most fundamental limit to the accurate estimation of the amplitude of the signal with known frequency. The variance of the conventional method can meet the limit only when the measurement time is much longer than the relaxation time of the pendulum. By using the maximum likelihood estimation and the equation-of-motion filter operator, we propose an optimal(minimum variance, unbiased) amplitude estimation method without limitation of the measurement time, where thermal fluctuation is the leading noise. While processing the experimental data tests of the Newtonian gravitational inverse square law, the variance of our method has been improved than before and the measurement time of determining the amplitude with this method has been reduced about half than before for the same uncertainty. These results are significant for the torsion experiment when the measurement time is limited.
基金Item Sponsored by National Natural Science Foundation of China (No.59874133) Creation Foundation of Shanghai Educational Committee (No.10YZ16)
文摘The parametric instability behavior of a liquid mercury sessile drop under high frequency Amplitude-Modulate Magnetic Field(AMMF),i.e.a high frequency magnetic field(carder wave)modulated by a low frequency sine wave(modulate wave),is investigated experimentally.The free surface contour of the mercury drop is observed by a CCD camera while varying the frequency and amplitude of the high frequency AMMF.At a given frequency and amplitude,the edge deformations with an azimuthal wave numbers(modes n=3,4,5,6)were excited.
基金Supported in part by research grants from the National Institute of Deafness and Other Communication Disorders(R01 DC 00141 and R03 DC033642)the National Institutes of Health+2 种基金the Research Fund of the American Otological Societythe Medical Research Foundation of OregonVA RR&D Center Grant RCTR-597-0160,Portland,VAMC
文摘Although stimulus frequency otoacoustic emissions (SFOAEs) have been used as a non-invasive measure of cochlear mechanics, clinical and experimental application of SFOAEs has been limited by difficulties in accurately deriving quantitative information from sound pressure measured in the ear canal. In this study, a novel signal processing method for multicomponent analysis (MCA) was used to measure the amplitude and delay of the SFOAE. This report shows the delay-frequency distribution of the SFOAE measured from the human ear. A low level acoustical suppressor near the probe tone significantly suppressed the SFOAE, strongly indicating that the SFOAE was generated at characteristic frequency locations. Information derived from this method may reveal more details of cochlear mechanics in the human ear.
基金Supported by National High-Technology Research and Development Plan of China (Grant No.2006AA01Z452)
文摘Amplitude quantization is one of the main sources of spurious noise frequencies in Direct Digital Frequency Synthesizers (DDFSs), which affect their application to many wireless telecommu- nication systems. In this paper, two different kinds of spurious signals due to amplitude quantization in DDFSs are exactly formulated in the time domain and detailedly compared in the frequency do- main, and the effects of the DDFS parameter variations on the spurious performance are thoroughly studied. Then the spectral properties and power levels of the amplitude-quantization spurs in the absence of phase-accumulator truncation are emphatically analyzed by waveform estimation and computer simulation, and several important conclusions are derived which can provide theoretical support for parameter choice and spurious performance evaluation in the application of DDFSs.
基金supported by the National Basic Research Program of China(Grant No.2013CB329202)the Basic Industrial Technology Project of China(Grant No.J312012B002)
文摘Satellite vibrations during exposure will lead to pixel aliasing of remote sensors, resulting in the deterioration of image quality. In this paper, we expose the problem and discuss the characteristics of satellite vibrations, and then present a pixel mixing model. The idea of mean mixing ratio （MMR） is proposed. MMR computations for different frequencies are implemented. In the mixing model, a coefficient matrix is introduced to estimate each mixed pixel. Thus, the simulation of degraded image can be performed when the vibration attitudes are known. The computation of MMR takes into considera- tion the influences of various frequencies and amplitudes. Therefore, the roles of these parameters played in the degradation progress are identified. Computations show that under the same vibration amplitude, the influence of vibrations fluctuates with the variation of frequency. The fluctuation becomes smaller as the frequency rises. Two kinds of vibration imaging experiments are performed： different amplitudes with the same frequency and different frequencies with the same amplitude. Results are found to be in very good agreement with the theoretical results. MMR has a better description of image quality than modulation transfer function （MTF）. The influence of vibrations is determined mainly by the amplitude rather than the frequency. The influence of vibrations on image quality becomes gradually stable with the increase of frequency.
