Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 32
Filtrar
Mais filtros

Base de dados
País/Região como assunto
Tipo de documento
Intervalo de ano de publicação
1.
Wei Sheng Yan Jiu ; 51(5): 761-766, 2022 Sep.
Artigo em Zh | MEDLINE | ID: mdl-36222037

RESUMO

OBJECTIVE: To explore the relationship between maternal sleep in the third trimester and 10-year risk of cardiovascular disease(CVD). METHODS: From March 2015 to July 2020, a total of 3034 pregnant women aged 18 to 45 years old with single pregnancy at the gestational age of 28 to 40 weeks in 3 hospitals in Hefei were enrolled in the study. Questionnaire survey was conducted to collect general demographic characteristics, lifestyles and sleep status. Total cholesterol(TC) and high-density lipoprotein cholesterol(HDL-C) were measured in venous blood. Restricted cubic spline regression model, Logistic regression model and stratified analysis were used to explore the association between sleep status and 10-year CVD risk. RESULTS: In the third trimester, the average sleep duration was(7.6±1.1) hours and the proportion of bedtime ≥22:00 was 82.7%. Sleep midpoint ≥02:30 accounted for 66.4% and wake up ≥07:00 accounted for 57.6%. The 10-year CVD risk prediction was(2.03±1.86)% and high-risk accounted for 10%(303 cases). In the restricted cubic spline regression, night sleep duration, bedtime, and getup with 10-year CVD risk had a downward trend(P<0.001). Logistic regression model result showed that short sleep duration(less than 8 hours) and wake up early(before 07:00 o'clock) and sleep midpoint before 02:30 was associated with a significantly higher 10-year CVD risk(OR=1.35, 95%CI 1.05-1.75;OR=2.23, 95%CI 1.71-2.90;OR=1.63, 95%CI 1.26-2.11). Further stratified analysis found that only among pregnant women with later bedtime(after 22:00 o'clock), short sleep duration(less than 8 hours) and wake up early(before 07:00 o'clock) and sleep midpoint before 02:30 was associated with significantly increased 10-year CVD risk(OR=1.53, 95%CI 1.14-2.05;OR=2.44, 95%CI 1.81-3.28;OR=1.85, 95%CI 1.37-2.50). CONCLUSION: In the third trimester, exposure to shorter sleep duration(less than 8 hours) or wake up early(before 07:00 o'clock) or sleep midpoint before 02:30 may increase the risk of 10-year CVD risk, in particular, for the pregnant women later bedtime(after 22:00 o'clock).


Assuntos
Doenças Cardiovasculares , Transtornos do Sono-Vigília , Adolescente , Adulto , Doenças Cardiovasculares/epidemiologia , Colesterol , Feminino , Humanos , Lactente , Lipoproteínas HDL , Pessoa de Meia-Idade , Gravidez , Gestantes , Sono , Adulto Jovem
2.
Cephalalgia ; 41(3): 366-374, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33175591

RESUMO

BACKGROUND: To evaluate the prevalence, predictive factors and clinical characteristics of cough headache in our respiratory clinic and to investigate the coexistence between cough headache, migraine and tension-type headache. METHOD: We consecutively investigated patients referred to our respiratory clinic with complaints of cough and selected patients with cough headaches to complete a structured interview and examination. RESULTS: Six hundred and seventy-nine patients with cough were studied and 122 patients were diagnosed with cough headache. The prevalence of cough headache was 18.0% in these coughing patients. According to multivariate analysis, being of an age between 31-50 years was a risk factor for cough headache (OR 2.0). Cough headache was associated with cough severity: Compared with the mild group, the moderate group (OR 2.3) and the severe group (OR 3.3) were more vulnerable to cough headache. Headache severity had a positive correlation with cough severity (ρ = 0.301, p = 0.028), age (ρ = 0.199, p = 0.029), and headache duration (ρ = 0.242, p = 0.008). In cough headache patients, 30.3% had tension-type headache and 10.7% had migraine in the preceding year. CONCLUSIONS: Cough headache is not rare in respiratory clinics and the characteristics are somewhat different from those in headache clinics. An age of between 31-50 years and cough severity were risk factors for cough headache. Headache severity was related to cough severity, age and headache duration.


Assuntos
Transtornos da Cefaleia Primários , Adulto , China/epidemiologia , Tosse/diagnóstico , Tosse/epidemiologia , Humanos , Pessoa de Meia-Idade , Transtornos de Enxaqueca , Prevalência
3.
BMC Plant Biol ; 19(1): 130, 2019 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-30961523

RESUMO

BACKGROUND: Potassium is a nutrient element necessary for tobacco growth. Tobacco leaves with high potassium content are elastic and tough, rich in oil. And the same time, potassium can also improve the scent and aromatic value of flue-cured tobacco by regulating the synthesis of aromatic hydrocarbons in leaves.. It is an important quality indicator for flue-cured tobacco. However, the potassium concentration in tobacco leaves in most areas of China is generally lower than the global standard for high quality tobacco. Two tobacco genotypes were grafted to each other under different potassium levels to test whether potassium content and plant growth can be improved by grafting in tobacco. RESULTS: The growth of tobacco in all treatments was inhibited under potassium starvation, and grafting significantly alleviated this potassium stress in 'Yunyan 87'. The trends in whole plant K+ uptake and K+ transfer efficiency to the leaves corresponded to the growth results of the different grafts. The nutrient depletion test results showed that the roots of 'Wufeng No.2' had higher K+ absorption potential, K+ affinity, and K+ inward flow rate. K+ enrichment circles appeared at the endoderm of the root section in the energy dispersive X-ray figure, indicating that the formation of Casparian strips may be partly responsible for the lower rate of lateral movement of K+ in the roots of 'Yunyan 87'. Gene expression analysis suggested that energy redistribution at the whole plant level might constitute one strategy for coping with potassium starvation. The feedback regulation effects between scion 'Wufeng No.2' and rootstock 'Yunyan 87' indicated that the transmission of certain signaling substances had occurred during grafting. CONCLUSIONS: 'Wufeng No.2' tobacco rootstock grafting can increase the K+ uptake and transport efficiency of 'Yunyan 87' and enhance plant growth under potassium stress. The physiological mechanism of the improved performance of grafted tobacco is related to higher K+ uptake and utilization ability, improved xylem K+ loading capacity, and up-regulated expression of genes related to energy supply systems.


Assuntos
Nicotiana/fisiologia , Potássio/metabolismo , Estresse Fisiológico , Transporte Biológico , Folhas de Planta/genética , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/fisiologia , Nicotiana/genética , Nicotiana/crescimento & desenvolvimento , Regulação para Cima , Xilema/genética , Xilema/crescimento & desenvolvimento , Xilema/fisiologia
4.
J Sci Food Agric ; 99(10): 4761-4771, 2019 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-30932195

RESUMO

BACKGROUND: Nitrogen availability is an important environmental factor that determines the production of phenolic compounds in vegetables, but the relationship between low nitrogen-induced alterations of phenolic compounds in vegetable crops and the cellular antioxidant activities of these compounds remains unclear. This study investigated the effect of reduced nitrogen supply (0.05 mmol L-1 nitrate) on phenolic metabolism in lettuce and the protective role of phenolic extracts against H2 O2 -induced oxidative stress in Caco-2 cells by determining cell damage, reactive oxygen species (ROS) content and antioxidant enzyme activities. RESULTS: Reduced nitrogen supply significantly improved the accumulation of phenolic compounds in lettuce, which was partially correlated with the upregulation of genes related to the phenolic synthesis pathway. Phenolic extracts from lettuce cultivated in low-nitrogen medium exhibited a better protective effect against H2 O2 -induced oxidative damage in Caco-2 cells than those from lettuce cultivated with adequate nitrogen. These extracts act by increasing the activities of antioxidant enzymes and, subsequently, by inhibiting ROS overproduction, which leads to a decrease in mitochondrial membrane and DNA damage. The results of HPLC and correlation analyses implied that the improvement in the protective capacity of lettuce extracts after low-nitrogen treatment may be related, not only to the increased content of phenolic compounds, but also to the increased percentage contribution of chlorogenic acid and quercetin derivatives to the total phenolic content. CONCLUSION: Reduction in nitrogen supply can be a powerful strategy to modify phenolic metabolism and composition in lettuce and, consequently, to improve their antioxidant capacity. © 2019 Society of Chemical Industry.


Assuntos
Antioxidantes/química , Lactuca/química , Nitratos/metabolismo , Fenóis/química , Antioxidantes/metabolismo , Antioxidantes/farmacologia , Células CACO-2 , Cromatografia Líquida de Alta Pressão , Dano ao DNA/efeitos dos fármacos , Humanos , Lactuca/metabolismo , Nitratos/análise , Estresse Oxidativo/efeitos dos fármacos , Fenóis/metabolismo , Fenóis/farmacologia , Folhas de Planta/química , Folhas de Planta/metabolismo , Verduras/química , Verduras/metabolismo
5.
Appl Opt ; 52(18): 4353-9, 2013 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-23842179

RESUMO

A self-adaptive method for distributed polarization extinction ratio (PER) demodulation is demonstrated. It is characterized by dynamic PER threshold coupling intensity (TCI) and nonuniform PER iteration step length (ISL). Based on the preset PER calculation accuracy and original distribution coupling intensity, TCI and ISL can be made self-adaptive to determine contributing coupling points inside the polarizing devices. Distributed PER is calculated by accumulating those coupling points automatically and selectively. Two different kinds of polarization-maintaining fibers are tested, and PERs are obtained after merely 3-5 iterations using the proposed method. Comparison experiments with Thorlabs commercial instrument are also conducted, and results show high consistency. In addition, the optimum preset PER calculation accuracy of 0.05 dB is obtained through many repeated experiments.

6.
Front Neurol ; 14: 1200846, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37576008

RESUMO

Purpose: Hypertension is an important risk factor for atherosclerotic cerebral small vessel disease (CSVD). Higher blood pressure is associated with a higher CSVD burden and the presence of relevant magnetic resonance imaging (MRI) markers. However, the effect of blood pressure level on CSVD burden and imaging markers including white matter hyperintensity (WHM), lacune, enlarged perivascular spaces (EPVS), and cerebral microbleed (CMB) remains unknown. The purpose of this study was to investigate the correlation between blood pressure level and CSVD burden at different time periods throughout the day. Methods: In total, 144 in-patients with CSVD (66.4 ± 9.8 years, 50% male) were enrolled and underwent brain MRI, and 24-h ambulatory blood pressure was assessed. Patients were categorized into five groups according to their MRI-evaluated total CSVD burden scores (0-4). Spearman's correlation analysis was performed to examine the correlation between blood pressure levels at different time periods and the total CSVD score or the markers of periventricular WMH, deep WMH, lacune, EPVS, and CMB. Results: Of the 144 patients, 83.3% (120/144) harbored one or more CSVD markers of interest. The systolic blood pressure (SBP) of 24-h, daytime, nighttime, and morning differed significantly among the five groups. The SBP levels increased significantly with the total CSVD scores during 24 h (P = 0.018), daytime (P = 0.018), and nighttime (P = 0.035). Spearman's correlation analysis demonstrated that the SBP of 24 h, daytime, nighttime, and morning and the diastolic blood pressure (DBP) of 24 h and morning positively and significantly correlated with the total CSVD score (P < 0.05). A logistic regression analysis indicated that both morning SBP and DBP were independent risk factors for total CSVD burden (OR = 1.13, 95% CI: 1.02-1.23, P = 0.015; OR = 1.19, 95% CI: 1.06-1.33, P = 0.005). Spearman's correlation analysis indicated a significant positive correlation between morning SBP and higher deep WMH Fazekas score (r = 0.296, P < 0.001), EPVS grade in the basal ganglia (r = 0.247, P = 0.003), and the presence of lacune (r = 0.173, P = 0.038) and CMB (r = 0.326, P < 0.001). Morning DBP only correlated positively with the presence of CMB (r = 0.292, P < 0.001). Conclusion: Higher SBP signficantly correlated with total CSVD burden in patients with atherosclerotic CSVD. Early morning blood pressure level is an important indicator to reflect the severity of CSVD patients.

7.
Neurology ; 101(14): e1466-e1472, 2023 10 03.
Artigo em Inglês | MEDLINE | ID: mdl-37491326

RESUMO

A 17-year-old girl presented with a long history of cognitive impairment, personality and behavioral changes, dysarthria, and paroxysmal lower-extremity weakness. She was initially suspected of having mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes because of stroke-like symptoms, such as episodic lower-extremity weakness, as well as abnormal brain MRI findings of generalized cerebral atrophy, extensive high-intensity lesions in the cortex and subcortical white matter on fluid-attenuated inversion recovery images, decreased N-acetyl aspartate/creatine ratio, and a lactate peak in the focal area on spectrum images. However, there were no relatives with similar presentations in the family of the patient. The whole mitochondrial genome and whole-exome sequencing did not suggest pathogenic mutations, and no abnormalities were found in the blood or CSF lactate levels. In this case, we detail the clinical manifestations, diagnostic workup, and imaging findings. This case highlights the importance of assessing cognitive function and the relevant differential diagnoses in an adolescent with cognitive impairment.


Assuntos
Acidose Láctica , Síndrome MELAS , Acidente Vascular Cerebral , Feminino , Adolescente , Humanos , Encéfalo/patologia , Imageamento por Ressonância Magnética , Acidose Láctica/patologia , Acidente Vascular Cerebral/patologia , Raciocínio Clínico , Síndrome MELAS/diagnóstico
8.
Sleep Health ; 9(4): 460-466, 2023 08.
Artigo em Inglês | MEDLINE | ID: mdl-37088599

RESUMO

OBJECTIVES: This study aimed to examine the association between sleep behaviors and cardiovascular health (CVH) during pregnancy and test whether high-sensitivity C-reactive protein (hs-CRP) mediates this association. METHODS: The study included 4204 pregnant women from the Maternal and Infant Health cohort study in Hefei (MIH-Hefei). Information on sleep (chronotype, sleep duration, snoring, daytime sleepiness, and insomnia) was collected through a touch-screen structured questionnaire at 16-23 weeks' gestation. CVH (body mass index, blood pressure, total cholesterol, glucose, and smoking) and hs-CRP were measured at 24-28 weeks' gestation. The role of hs-CRP in the association between sleep and CVH was explored in a mediation analysis, while adjusting for multiple confounding factors. RESULTS: Poor sleep score was significantly associated with poor gestational CVH metrics, including an RR of 0.872 (95% CI, 0.810, 0.938) for having all ideal (vs. any nonideal) CVH metrics; hs-CRP level was significantly associated with poor gestational CVH metrics, including an RR of 0.531 (95% CI, 0.432, 0.609) for having all ideal (vs. any nonideal) CVH metrics. Sleep scores were positively correlated with hs-CRP level (ß, 0.020, 95% CI, 0.006, 0.034). Mediation analysis revealed that the association between sleep and CVH mediated by hs-CRP was 12.31% (indirect effect, -0.0095, 95% CI, -0.0167, -0.0042). CONCLUSIONS: Poor sleep during pregnancy, particularly late chronotype and snoring, may worsen CVH by increasing systemic chronic inflammation.


Assuntos
Proteína C-Reativa , Inflamação , Complicações Cardiovasculares na Gravidez , Distúrbios do Início e da Manutenção do Sono , Adulto , Feminino , Humanos , Gravidez , Proteína C-Reativa/análise , China , Doença Crônica , Cronotipo , Estudos de Coortes , Fatores de Confusão Epidemiológicos , Distúrbios do Sono por Sonolência Excessiva/sangue , Distúrbios do Sono por Sonolência Excessiva/complicações , Idade Gestacional , Inflamação/sangue , Inflamação/complicações , Análise de Mediação , Complicações Cardiovasculares na Gravidez/sangue , Complicações Cardiovasculares na Gravidez/etiologia , Segundo Trimestre da Gravidez/sangue , Duração do Sono , Distúrbios do Início e da Manutenção do Sono/sangue , Distúrbios do Início e da Manutenção do Sono/complicações , Ronco/sangue , Ronco/complicações
9.
Opt Express ; 20(8): 8862-70, 2012 Apr 09.
Artigo em Inglês | MEDLINE | ID: mdl-22513596

RESUMO

A radio frequency (RF) carrier can be used to mitigate the phase noise impact in n-level PSK and QAM systems. The systems performance is influenced by the use of an RF pilot carrier to accomplish phase noise compensation through complex multiplication in combination with discrete filters to compensate for the chromatic dispersion (CD). We perform a detailed study comparing two filters for the CD compensation namely the fixed frequency domain equalizer (FDE) filter and the adaptive least-mean-square (LMS) filter. The study provides important novel physical insight into the equalization enhanced phase noise (EEPN) influence on the system bit-error-rate (BER) versus optical signal-to-noise-ratio (OSNR) performance. Important results of the analysis are that the FDE filter position relative to the RF carrier phase noise compensation module provides a possibility for choosing whether the EEPN from the Tx or the LO laser influences the system quality. The LMS filter works very inefficiently when placed prior to the RF phase noise compensation stage of the Rx whereas it works much more efficiently and gives almost the same performance as the FDE filter when placed after the RF phase noise compensation stage.

10.
Opt Express ; 20(16): 18117-26, 2012 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-23038359

RESUMO

A demodulation algorithm based on absolute phase recovery of a selected monochromatic frequency is proposed for optical fiber Fabry-Perot pressure sensing system. The algorithm uses Fourier transform to get the relative phase and intercept of the unwrapped phase-frequency linear fit curve to identify its interference-order, which are then used to recover the absolute phase. A simplified mathematical model of the polarized low-coherence interference fringes was established to illustrate the principle of the proposed algorithm. Phase unwrapping and the selection of monochromatic frequency were discussed in detail. Pressure measurement experiment was carried out to verify the effectiveness of the proposed algorithm. Results showed that the demodulation precision by our algorithm could reach up to 0.15kPa, which has been improved by 13 times comparing with phase slope based algorithm.

11.
Phys Rev E ; 105(5-2): 055108, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35706206

RESUMO

Direct numerical simulations of electroconvection instability near an ion-selective surface are conducted using a mesoscopic lattice Boltzmann method (LBM). An electrohydrodynamic model of ion transport and fluid flow is presented. We numerically solve the Poisson-Nernst-Planck equations for the electric field and the Navier-Stokes equations for the flow field. The results cover Ohmic, limiting, and overlimiting current regimes, and they are in good agreement with the asymptotic analytical solution for the relationship between current and voltage. The influences of different ion transport mechanisms on the voltage-current relationship are discussed. The results reveal that the electroconvection mechanism is as important as other ion transport mechanisms in electrohydrodynamic flow. By comparing the contribution of different regions in the numerical domain, we find that the flow in the extended space charge layer is dominated by electroconvection. We also study the influences of multiple driving parameters, and the electrohydrodynamic coupling constant plays a dominant role in triggering convective instability. The flow pattern and ion concentration distribution are described in detail. Moreover, the route of flow from steady state to periodic oscillation and then to chaos is discussed.

12.
Front Neurosci ; 16: 1056261, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36545534

RESUMO

Background: Neuronal intranuclear inclusion disease (NIID) is a rare chronic progressive neurodegenerative disease, with complex and diverse clinical manifestations and pathological eosinophilic hyaline intranuclear inclusions in the central and peripheral nervous systems and visceral organs. Improvements in diagnostic methods such as skin biopsy and gene testing are helpful in revealing the clinical and genetic characters of NIID. Materials and methods: We presented two cases of NIID diagnosed by using NOTCH2NLC gene testing and skin biopsy. Diffusion weighted imaging (DWI) showed high linear intensity in corticomedullary junction. We also reviewed all the published NIID cases with positive NOTCH2NLC GGC repeat expansion and skin biopsy results in PubMed. Results: Patient 1 was a 63-year-old male who carried 148 GGC repeats and presented with progressive tremor and limb weakness. Patient 2 was a 62-year-old woman who carried 131 GGC repeats and presented with tremors, memory loss and headaches. The most common clinical manifestation of 63 NIID patients in this study was cognitive impairment, followed by tremors. In our study, almost all the patients were from East Asia, the male to female ratio was 1:1.26, with an age of onset of 54.12 ± 14.12 years, and an age of diagnosis of 60.03 ± 12.21 years. Symmetrical high signal intensity at the corticomedullary junction on DWI were revealed in 80.96% of the patients. For the GGC repeat numbers, the majority of GGC repeats were in the 80-119 intervals, with few GGC repeats above 160. The number of GGC repetitions was significantly higher in patients presented with muscle weakness than in other clinical manifestations. Conclusion: NIID is a neurodegenerative disease caused by aberrant polyglycine (polyG) protein aggregation. NIID mostly occurs in the elderly population in East Asia, with cognitive dysfunction as the most common symptom. Staging NIID based on clinical presentation is inappropriate because most patients with NIID have overlapping symptoms. In our study, there was no significant correlation between the number of GGC repeats and different phenotypes except for muscle weakness. Abnormal trinucleotides repeat and PolyG protein aggregation maybe common pathogenic mechanism in neurodegenerative diseases and cerebrovascular diseases, which needs to be confirmed by more studies.

13.
Opt Express ; 19(15): 14487-94, 2011 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-21934811

RESUMO

In this paper, a novel method for extracting an RF pilot carrier signal in the coherent receiver is presented. The RF carrier is used to mitigate the phase noise influence in n-level PSK and QAM systems. The performance is compared to the use of an (ideal) optically transmitted RF pilot tone. As expected an electronically generated RF carrier provides less efficient phase noise mitigation than the optical RF. However, the electronically generated RF carrier still improves the phase noise tolerance by about one order of magnitude in bit error rate (BER) compared to using no RF pilot tone. It is also found, as a novel study result, that equalization enhanced phase noise--which appears as correlated pure phase noise, amplitude noise and time jitter-cannot be efficiently mitigated by the use of an (optically or electrically generated) RF pilot tone.

14.
Opt Express ; 19(8): 7756-68, 2011 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-21503086

RESUMO

We present a novel investigation on the enhancement of phase noise in coherent optical transmission system due to electronic chromatic dispersion compensation. Two types of equalizers, including a time domain fiber dispersion finite impulse response (FD-FIR) filter and a frequency domain blind look-up (BLU) filter are applied to mitigate the chromatic dispersion in a 112-Gbit/s polarization division multiplexed quadrature phase shift keying (PDM-QPSK) transmission system. The bit-error-rate (BER) floor in phase estimation using an optimized one-tap normalized least-mean-square (NLMS) filter, and considering the equalization enhanced phase noise (EEPN) is evaluated analytically including the correlation effects. The numerical simulations are implemented and compared with the performance of differential QPSK demodulation system.

15.
Guang Pu Xue Yu Guang Pu Fen Xi ; 31(8): 2040-3, 2011 Aug.
Artigo em Zh | MEDLINE | ID: mdl-22007380

RESUMO

Due to the advantages of immunity of electrical/electronic, high performance cost ratio, remote detection and multiplexing capability, intra-cavity fiber optic gas measurement has aroused wide concern. The trace gas measurement system has been developed based on the elaborated gas cell and reflector. The wavelength sweeping technique (WST) is realized when the Fabry-Perot type tunable optical filter is applied by the sawtooth driver voltage. Multi absorption lines can be obtained and one scanning measurement with WST is equal to multiple independent detections, so the gas measurement sensitivity is improved remarkably. The experimental results show that the acetylene detection sensitivity is reduced to less than 100 ppm and the relative measurement error is less than 3% of practical gas concentration.

16.
Rev Sci Instrum ; 92(5): 053547, 2021 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-34243352

RESUMO

A time-of-flight neutron spectrometer based on the Time-Of-Flight Enhanced Diagnostic (TOFED) concept has been designed and is under development for the Large Helical Device (LHD). It will be the first advanced neutron spectrometer to measure the 2.45 MeV D-D neutrons (DDNs) from helical/stellarator plasmas. The main mission of the new TOFED is to study the supra-thermal deuterons generated from the auxiliary heating systems in helical plasmas by measuring the time-of-flight spectra of DDN. It will also measure the triton burnup neutrons (TBNs) from the d+t reactions, unlike the original TOFED in the EAST tokamak. Its capability of diagnosing the TBN ratios is evaluated in this work. This new TOFED is expected to be installed in the basement under the LHD hall and shares the collimator with one channel of the vertical neutron camera to define its line of sight. The distance from its primary scintillators to the equatorial plane of LHD plasmas is about 15.5 m. Based on Monte Carlo simulation by a GEANT4 model, the resolution of the DDN energy spectra is 6.6%. When projected onto the neutron rates that are typically obtained in LHD deuterium plasmas (an order of 1015 n/s with neutral beam injection), we expect to obtain the DDN and TBN counting rates of about 2.5 · 105 counts/s and 250 counts/s, respectively. This will allow us to analyze the DDN time-of-flight spectra on time scales of 0.1 s and diagnose the TBN emission rates in several seconds with one instrument, for the first time in helical/stellarator plasmas.

17.
Opt Express ; 18(15): 16243-57, 2010 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-20721010

RESUMO

We present a comparative analysis of three popular digital filters for chromatic dispersion compensation: a time-domain least mean square adaptive filter, a time-domain fiber dispersion finite impulse response filter, and a frequency-domain blind look-up filter. The filters are applied to equalize the chromatic dispersion in a 112-Gbit/s non-return-to-zero polarization division multiplexed quadrature phase shift keying transmission system. The characteristics of these filters are compared by evaluating their applicability for different fiber lengths, their usability for dispersion perturbations, and their computational complexity. In addition, the phase noise tolerance of these filters is also analyzed.

18.
Guang Pu Xue Yu Guang Pu Fen Xi ; 30(11): 3076-80, 2010 Nov.
Artigo em Zh | MEDLINE | ID: mdl-21284187

RESUMO

Optical biosensors are becoming an important tool for drug research and life science, and the label-free optical biosensor based on whisper-gallery-mode (WGM) is reviewed in the present paper. The WGM-based sensors are categorized into three types according to the microcavity structure. The biosensor using microsphere got extensive research because of high quality factor, and its response to protein, virus, and bacteria had been studied. The models based on single photon resonant state and perturbation theory were established. The biosensor using microdisk was proposed early since it can make use of mature lithography technology; however, the quality factor was increased greatly only after the thermal reflow process was introduced and single molecule measurement was then realized. The biosensor using microring has simpler mode structure and materials such as polymer, silicon nitride and silicon-on-insulator had been used for sensor fabrication. As a 3-dimension expansion, sensor using microtube can combine the optical channel and fluidic channel, which attracting more and more attention.


Assuntos
Técnicas Biossensoriais , Microesferas , Modelos Teóricos , Nanotecnologia , Fótons , Silício
19.
Appl Opt ; 48(36): 7000-7, 2009 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-20029603

RESUMO

We present a method for the trajectory and the velocity measurement of a particle in spray by digital holography. Based on multiple exposure digital in-line holography, a sequence of digital holograms of a dynamic spray particle field at different times are recorded with a CW laser and a high-speed CCD. The time evolution of the serial positions of particles, i.e., the motion trajectories of the particles, is obtained by numerically reconstructing the synthetic hologram of a sequence of digital holograms. The center coordinate (x,y) of each particle image can be extracted using a Hough transform and subpixel precision computing, and the velocity of an individual particle can also be obtained, which is then applied to measuring the velocity of diesel spray and alcohol spray. The research shows that the method presented in this paper for measuring spray field is feasible.

20.
IEEE J Biomed Health Inform ; 23(3): 1141-1150, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30004893

RESUMO

Human skin temperature mapping provides abundant information of physiological conditions of human body, which provides supplementary or alternative indicators for disease monitoring or diagnosis. The existing models of temperature mapping or temperature field distribution of human skin are generally established by finite element method. Due to the complexity of biological systems, it is challenging to achieve high accuracy mathematical models of temperature field of human skin. The goal of this study is to establish human skin temperature three-dimensional (3-D) mapping platform by integrating optical fibers and improved genetic algorithm-back propagation (GA-BP) neural network. The proposed data-driven method is capable of acquiring entire human skin temperature 3-D mapping by simply measuring a few points on human skin. Multiple experiments were conducted to validate the proposed method on different areas of human skin in different ambient environments. In each experiment setting, the measured data and the model output data were compared. The mean absolute error in all the validation experiments is 0.11 °C, which is lower than that in the state of the art using physical modeling for skin temperature prediction and more close to clinical accuracy. The results show that the proposed approach is accurate and reliable, which may provide a platform technology for human skin temperature mapping that can be used in both medical and scientific studies as well as home monitoring.


Assuntos
Imageamento Tridimensional/métodos , Temperatura Cutânea/fisiologia , Termografia/métodos , Algoritmos , Antebraço/diagnóstico por imagem , Humanos , Redes Neurais de Computação , Fibras Ópticas
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA