AIM:To investigate the effects of different light intensities and various mydriatic and miotic drugs on pupil accommodation in guinea pigs.METHODS:Forty-two-week-old guinea pigs were randomly divided into four groups ...AIM:To investigate the effects of different light intensities and various mydriatic and miotic drugs on pupil accommodation in guinea pigs.METHODS:Forty-two-week-old guinea pigs were randomly divided into four groups to assess pupillary responses under varying light intensities(100,250,500 lx)and pharmacological interventions(1%atropine,1%cyclopentolate,1%tropicamide,or 2%pilocarpine).Baseline pupil size and eccentricity were recorded using a non-contact Python-based imaging system integrating edge detection and pixel-to-distance conversion.Direct illumination effects were measured at sequential time points,followed by drug administration and longitudinal tracking of pupillary changes.The protocol was repeated at 12wk of age for developmental comparisons.Postexperiment,enucleated eyes were analyzed to evaluate in vitro vs in vivo differences.RESULTS:Significant age-dependent differences in pupil dynamics were observed.Both 2-and 12-week-old guinea pigs exhibited marked pupil constriction under direct illumination(P<0.001),with decreased eccentricity post-constriction(P<0.001).Indirect illumination caused inconsistent pupil size changes(2-week:P=0.68;12-week:P=0.49).Pharmacologically,atropine,cyclopentolate,and tropicamide induced pupil dilation(P<0.001),whereas pilocarpine caused constriction(P<0.001).All drug groups showed reduced eccentricity(P<0.001).In vivo/in vitro comparisons revealed significant structural differences.CONCLUSION:This study investigates pupillary responses in developing guinea pigs,revealing a direct pupillary light reflex(PLR)with light intensity-dependent responses,while indirect PLR was undetectable.The differential effects of muscarinic modulators on pupillary responses underscore the critical role of cholinergic signaling in ocular accommodation,with age-related variations in sensitivity.Additionally,a novel non-contact measurement methodology achieved a precision of 0.01 mm for pupillary quantification,enhancing accuracy in ocular studies.展开更多
Lysophosphatidic acid(LPA)is a pleiotropic lipid agonist essential for functions of the central nervous system(CNS).It is abundant in the developing and adult brain while its concentration in biological fluids,includi...Lysophosphatidic acid(LPA)is a pleiotropic lipid agonist essential for functions of the central nervous system(CNS).It is abundant in the developing and adult brain while its concentration in biological fluids,including cerebrospinal fluid,varies significantly(Figure 1Α;Yung et al.,2014).LPA actually corresponds to a variety of lipid species that include different stereoisomers with either saturated or unsaturated fatty acids bearing likely differentiated biological activities(Figure 1Α;Yung et al.,2014;Hernández-Araiza et al.,2018).展开更多
In this paper,we present a novel first-order digitalΣΔconverter tailored for digital-to-analog applications,focusing on achieving both high yield and reduced silicon estate.Our approach incorporates a substantial le...In this paper,we present a novel first-order digitalΣΔconverter tailored for digital-to-analog applications,focusing on achieving both high yield and reduced silicon estate.Our approach incorporates a substantial level of dithering noise into the input signal,strategically aimed at mitigating the spurious frequencies commonly encountered in such converters.Validation of our design is performed through simulations using a high-level simulator specialized in mixed-signal circuit analysis.The results underscore the enhanced performance of our circuit,especially in reducing spurious frequencies,highlighting its efficiency and effectiveness.The final circuit exhibits an effective number of bits of 13.展开更多
A quadrature modulator and an up-conversion mixer for an 802. lla wireless LAN system are designed and fabricated in 0.18μm gate length standard CMOS technology. A current feedback loop with a transconductor is used ...A quadrature modulator and an up-conversion mixer for an 802. lla wireless LAN system are designed and fabricated in 0.18μm gate length standard CMOS technology. A current feedback loop with a transconductor is used to improve the linearity of the quadrature modulator;An LC resonant tank is used as the load of the upconversion mixer to improve its gain and increase the voltage swing. The measurement results show that the input P1dB achieves -3.6dBm, the transducer power gain of the circuit is -3.6dB,and the current consumes about 45.8mA with a 1.8V power supply.展开更多
We report a wavelength tunable electro-absorption modulated DBR laser based on a combined method of SAG and QWI. The threshold current is 37mA and the output power at 100mA gain current is 3.5mW. When coupled to a sin...We report a wavelength tunable electro-absorption modulated DBR laser based on a combined method of SAG and QWI. The threshold current is 37mA and the output power at 100mA gain current is 3.5mW. When coupled to a single-mode fiber with a coupling efficiency of 15% ,more than a 20dB extinction ratio is observed over the change of EAM bias from 0 to -2V. The 4.4nm continuous wavelength tuning range covers 6 channels on a 100GHz grid for WDM telecommunications.展开更多
The liquid crystal spatial light modulator （LC SLM） is very suitable for wavefront correction and optical testing and can produce a wavefront with large phase change and high accuracy. The LC SLM is composed of thou...The liquid crystal spatial light modulator （LC SLM） is very suitable for wavefront correction and optical testing and can produce a wavefront with large phase change and high accuracy. The LC SLM is composed of thousands of pixels and the pixel size and shape have effects on the diffractive characteristics of the LC SLM. This paper investigates the pixel effect on the phase of the wavefront with the scalar diffractive theory. The results show that the maximum optical path difference modulation is 41μm to produce the paraboloid wavefront with the peak to valley accuracy better than λ/10. Effects of the mismatch between the pixel and the period, and black matrix on the diffraction efficiency of the LC SLM are also analysed with the Fresnel phase lens model. The ability of the LC SLM is discussed for optical testing and wavefront correction based on the calculated results. It shows that the LC SLM can be used as a wavefront corrector and a compensator.展开更多
This paper presents the design considerations and implementation of a novel topology digital multistage-noise-shaping （MASH） delta-sigma modulator suitable for fractional-N phase-locked-loop （PLL） frequency synthe...This paper presents the design considerations and implementation of a novel topology digital multistage-noise-shaping （MASH） delta-sigma modulator suitable for fractional-N phase-locked-loop （PLL） frequency synthesis. In an effort to reduce the complexity and dissipation,a pipeline technique has been used, and the proposed carry save tree （CST） algorithm optimizes the multi-input adder structure. The circuit has been verified through Matlab simulation, ASIC implementation, and FPGA experiment, which exhibits high performance and potential for a gigahertz range,low-power monolithic CMOS frequency synthesizer.展开更多
Bone morphogenetic proteins are essential for bone regeneration/fracture healing but can also induce heterotopic ossification(HO).Understanding accessory factors modulating BMP signaling would provide both a means of ...Bone morphogenetic proteins are essential for bone regeneration/fracture healing but can also induce heterotopic ossification(HO).Understanding accessory factors modulating BMP signaling would provide both a means of enhancing BMP-dependent regeneration while preventing HO.This study focuses on the ability of the collagen receptor,discoidin domain receptor 2(DDR2),to regulate BMP activity.As will be shown,induction of bone formation by subcutaneous BMP2 implants is severely compromised in Ddr2-deficient mice.In addition,Ddr2 deficiency attenuates HO in mice expressing the ACVR1 mutation associated with human fibrodysplasia ossificans progressiva.In cells migrating into BMP2 implants,DDR2 is co-expressed with GLI1,a skeletal stem cell marker,and DDR2/GLI1-positive cells participate in BMP2-induced bone formation where they contribute to chondrogenic and osteogenic lineages.Consistent with this distribution,conditional knockout of Ddr2 in Gli1-expressing cells inhibited bone formation to the same extent seen in globally Ddr2-deficient animals.This response was explained by selective inhibition of Gli1+cell proliferation without changes in apoptosis.The basis for this DDR2 requirement was explored further using bone marrow stromal cells.Although Ddr2 deficiency inhibited BMP2-dependent chondrocyte and osteoblast differentiation and in vivo,bone formation,early BMP responses including SMAD phosphorylation remained largely intact.Instead,Ddr2 deficiency reduced the nuclear/cytoplasmic ratio of the Hippo pathway intermediates,YAP and TAZ.This suggests that DDR2 regulates Hippo pathway-mediated responses to the collagen matrix,which subsequently affect BMP responsiveness.In summary,DDR2 is an important modulator of BMP signaling and a potential therapeutic target both for enhancing regeneration and treating HO.展开更多
Spatial memory is crucial for survival within external surroundings and wild environments.The hippocampus,a critical hub for spatial learning and memory formation,has received extensive investigations on how neuromodu...Spatial memory is crucial for survival within external surroundings and wild environments.The hippocampus,a critical hub for spatial learning and memory formation,has received extensive investigations on how neuromodulators shape its functions(Teixeira et al.,2018;Zhang et al.,2024).However,the landscape of neuromodulations in the hippocampal system remains poorly understood because most studies focus on classical monoamine neuromodulators,such as acetylcholine,serotonin,dopamine,and noradrenaline.The neuropeptides,comprising the most abundant neuromodulators in the central nervous system,play a pivotal role in neural information processing in the hippocampal system.Cholecystokinin(CCK),one of the most abundant neuropeptides,has been implicated in regulating various physiological and neurobiological statuses(Chen et al.,2019).CCK-A receptor(CCK-AR)and CCK-B receptors(CCK-BR)are two key receptors mediating the biological functions of CCK,both of which belong to class-A sevenfold transmembrane G protein-coupled receptors(Nishimura et al.,2015).CCK-AR preferentially reacts to sulfated CCK,whereas CCK-BR binds both CCK and gastrin with similar affinities(Ding et al.,2022).The expression patterns of CCK-AR and CCK-BR are distinct,implying that CCK has various functions in target regions.For instance,CCK-AR is widely expressed in the GI and brain subregions and is hence implicated in the control of digestive function and satiety regulation.Conversely,CCK-BR is abundantly and widely distributed in the central nervous system,which majorly regulates anxiety,learning,and memory(Ding et al.,2022).However,the roles of endogenous CCK and CCK receptors in regulating hippocampal function at electrophysiological and behavioral levels have received less attention.展开更多
Astrocytes,the main population of glial cells in the central nervous system(CNS),exert essential tasks for the control of brain tissue homeostasis,supporting neuron and other glial cell activity from the developmental...Astrocytes,the main population of glial cells in the central nervous system(CNS),exert essential tasks for the control of brain tissue homeostasis,supporting neuron and other glial cell activity from the developmental stage to adult life.To maintain the optimal functionality of the brain,astroglial cells are particularly committed to reacting to every change in tissue homeostatic conditions,from mild modifications of the physiological environment,a process called astrocyte activation,to the more severe alterations occurring in pathological situations causing astrocyte reactivity or reactive astrogliosis(Escartin et al.,2021).During these reactive states,astrocytes mount an active,progressive response encompassing morphological,molecular,and interactional remodeling,leading to the acquisition of new functions and the loss of others,whose intensity,duration,and reversibility are dependent on the nature of the stimulus and regulated in a context-specific manner.展开更多
In terahertz communication,the direct frequency conversion structure in which orthogonal mixer is the main frequency conversion unit,makes engineers get into trouble of in-phase(I)branch and quadrature(Q)branch imbala...In terahertz communication,the direct frequency conversion structure in which orthogonal mixer is the main frequency conversion unit,makes engineers get into trouble of in-phase(I)branch and quadrature(Q)branch imbalance,carrier wave leakage,etc.These damages result in system performance tremendous degrades.We proposed a semiblind method to estimate the I/Q imbalance of THz orthogonal modulator,based on predefined preamble and pilot symbols for quadrature amplitude modulation(QAM).In this paper,a transmitter with Y band quadrature mixer and 20Gbps base-band signal has been tested.The bandwidth of the baseband signal was 7GHz,and the modulation type was 16QAM.By this method,7dB improvement of the system’s symbol Mean Square Error(MSE)has been got.That means the proposed method can be used to eliminate the I/Q imbalance effectively.展开更多
In a quantum key distribution system, it is crucial to keep the extinction ratio of the coherent pulses stable. This means that the direct current bias point of the electro-optic modulator （EOM） used for generating ...In a quantum key distribution system, it is crucial to keep the extinction ratio of the coherent pulses stable. This means that the direct current bias point of the electro-optic modulator （EOM） used for generating coherent pulses must be locked. In this paper, an autobias control system based on a lock-in-amplifier for the EOM is introduced. Its drift information extracting theory and control method are analyzed comprehensively. The long term drift of the extinction ratio of the coherent pulses is measured by a single photon detector, which indicates that the autobias control system is effective for stabilizing the bias point of the EOM.展开更多
Liquid crystal spatial light modulator （LCSLM） realizing equal-intensity multiple beams often has some features, i.e., phase valley between two adjacent pixels, flybaek region when phase decreases immediately from 2...Liquid crystal spatial light modulator （LCSLM） realizing equal-intensity multiple beams often has some features, i.e., phase valley between two adjacent pixels, flybaek region when phase decreases immediately from 2~r to 0, and inevitable backplane curvature, which are different from those of most conventional diffractive optical elements （DOEs）, such as static DOEs. For optimal intensity uniformity, equal-intensity multi-beam generation must be considered for these artifacts. We present a tunable-grating method in which the intensity uniformity can be improved by considering the LCSLM artifacts. For instance, tuning phase modulation depth of the grating, called isosceles triangle multilevel phase grating （ITMPG）, can be used not only to improve the intensity uniformity, but also to fast steer four beams with narrow beamwidths, determined by the same effective aperture of ITMPG. Improved intensity uniformity and high relative diffraction efficiency are demonstrated through experiments with phase-only LCSLM.展开更多
A novel technique is proposed for the generation of ultra-wide and flat optical frequency comb(OFC)based on serially cascading three stages of electro absorption modulators(EAMs)through sinusoidal radio frequency(RF)s...A novel technique is proposed for the generation of ultra-wide and flat optical frequency comb(OFC)based on serially cascading three stages of electro absorption modulators(EAMs)through sinusoidal radio frequency(RF)signals by setting frequencies at f GHz,f/2 GHz and f/4 GHz.Here,the first stage acts as subcarrier generator,the second stage acts as subcarrier doubler,and the third stage acts as subcarrier quadrupler.In addition,a higher number of subcarriers can easily be generated by adjusting the driving sinusoidal RF signal.In this paper,cascading three stages of EAMs driven by50 GHz,25 GHz and 12.5 GHz clock sources,we obtain 272 subcarriers with spacing of 2.5 GHz and power deviation within 1 d B.Theoretical analysis of serially cascaded EAMs for subcarrier generation is also investigated.Principal analysis and simulation of this technique are demonstrated.展开更多
An approach for generating optical frequency comb(OFC)with tunable free spectral range(FSR)is proposed.Two Mach-Zehnder modulators(MZMs)driven by phase-shifted sinusoidal signals are cascaded to generate OFC with plen...An approach for generating optical frequency comb(OFC)with tunable free spectral range(FSR)is proposed.Two Mach-Zehnder modulators(MZMs)driven by phase-shifted sinusoidal signals are cascaded to generate OFC with plentiful comb lines and the FSR controlled by the drive frequency.Subsequently,a linearly chirped fiber Bragg grating(LCFBG)and a phase modulator(PM)are used to increase the comb FSR by a particular integer multiple.Therefore,by simultaneously controlling the drive frequency of MZMs,the dispersion amount of the LCFBG and the drive signal of the PM,an OFC with desired FSR can be achieved.展开更多
文摘AIM:To investigate the effects of different light intensities and various mydriatic and miotic drugs on pupil accommodation in guinea pigs.METHODS:Forty-two-week-old guinea pigs were randomly divided into four groups to assess pupillary responses under varying light intensities(100,250,500 lx)and pharmacological interventions(1%atropine,1%cyclopentolate,1%tropicamide,or 2%pilocarpine).Baseline pupil size and eccentricity were recorded using a non-contact Python-based imaging system integrating edge detection and pixel-to-distance conversion.Direct illumination effects were measured at sequential time points,followed by drug administration and longitudinal tracking of pupillary changes.The protocol was repeated at 12wk of age for developmental comparisons.Postexperiment,enucleated eyes were analyzed to evaluate in vitro vs in vivo differences.RESULTS:Significant age-dependent differences in pupil dynamics were observed.Both 2-and 12-week-old guinea pigs exhibited marked pupil constriction under direct illumination(P<0.001),with decreased eccentricity post-constriction(P<0.001).Indirect illumination caused inconsistent pupil size changes(2-week:P=0.68;12-week:P=0.49).Pharmacologically,atropine,cyclopentolate,and tropicamide induced pupil dilation(P<0.001),whereas pilocarpine caused constriction(P<0.001).All drug groups showed reduced eccentricity(P<0.001).In vivo/in vitro comparisons revealed significant structural differences.CONCLUSION:This study investigates pupillary responses in developing guinea pigs,revealing a direct pupillary light reflex(PLR)with light intensity-dependent responses,while indirect PLR was undetectable.The differential effects of muscarinic modulators on pupillary responses underscore the critical role of cholinergic signaling in ocular accommodation,with age-related variations in sensitivity.Additionally,a novel non-contact measurement methodology achieved a precision of 0.01 mm for pupillary quantification,enhancing accuracy in ocular studies.
基金supported by the Hellenic Foundation for Research and Innovation,HFRI,“2nd Call for HFRI Research Projects to support Faculty Members&Researchers”Project 02667 to GL.
文摘Lysophosphatidic acid(LPA)is a pleiotropic lipid agonist essential for functions of the central nervous system(CNS).It is abundant in the developing and adult brain while its concentration in biological fluids,including cerebrospinal fluid,varies significantly(Figure 1Α;Yung et al.,2014).LPA actually corresponds to a variety of lipid species that include different stereoisomers with either saturated or unsaturated fatty acids bearing likely differentiated biological activities(Figure 1Α;Yung et al.,2014;Hernández-Araiza et al.,2018).
文摘In this paper,we present a novel first-order digitalΣΔconverter tailored for digital-to-analog applications,focusing on achieving both high yield and reduced silicon estate.Our approach incorporates a substantial level of dithering noise into the input signal,strategically aimed at mitigating the spurious frequencies commonly encountered in such converters.Validation of our design is performed through simulations using a high-level simulator specialized in mixed-signal circuit analysis.The results underscore the enhanced performance of our circuit,especially in reducing spurious frequencies,highlighting its efficiency and effectiveness.The final circuit exhibits an effective number of bits of 13.
文摘A quadrature modulator and an up-conversion mixer for an 802. lla wireless LAN system are designed and fabricated in 0.18μm gate length standard CMOS technology. A current feedback loop with a transconductor is used to improve the linearity of the quadrature modulator;An LC resonant tank is used as the load of the upconversion mixer to improve its gain and increase the voltage swing. The measurement results show that the input P1dB achieves -3.6dBm, the transducer power gain of the circuit is -3.6dB,and the current consumes about 45.8mA with a 1.8V power supply.
文摘We report a wavelength tunable electro-absorption modulated DBR laser based on a combined method of SAG and QWI. The threshold current is 37mA and the output power at 100mA gain current is 3.5mW. When coupled to a single-mode fiber with a coupling efficiency of 15% ,more than a 20dB extinction ratio is observed over the change of EAM bias from 0 to -2V. The 4.4nm continuous wavelength tuning range covers 6 channels on a 100GHz grid for WDM telecommunications.
基金Project supported by the National Natural Science Foundation of China （Nos 60578035, 50473040） and the Science Foundation of Jilin Province （Nos 20050520, 20050321-2）.
文摘The liquid crystal spatial light modulator （LC SLM） is very suitable for wavefront correction and optical testing and can produce a wavefront with large phase change and high accuracy. The LC SLM is composed of thousands of pixels and the pixel size and shape have effects on the diffractive characteristics of the LC SLM. This paper investigates the pixel effect on the phase of the wavefront with the scalar diffractive theory. The results show that the maximum optical path difference modulation is 41μm to produce the paraboloid wavefront with the peak to valley accuracy better than λ/10. Effects of the mismatch between the pixel and the period, and black matrix on the diffraction efficiency of the LC SLM are also analysed with the Fresnel phase lens model. The ability of the LC SLM is discussed for optical testing and wavefront correction based on the calculated results. It shows that the LC SLM can be used as a wavefront corrector and a compensator.
文摘This paper presents the design considerations and implementation of a novel topology digital multistage-noise-shaping （MASH） delta-sigma modulator suitable for fractional-N phase-locked-loop （PLL） frequency synthesis. In an effort to reduce the complexity and dissipation,a pipeline technique has been used, and the proposed carry save tree （CST） algorithm optimizes the multi-input adder structure. The circuit has been verified through Matlab simulation, ASIC implementation, and FPGA experiment, which exhibits high performance and potential for a gigahertz range,low-power monolithic CMOS frequency synthesizer.
基金Scientific Research Training Program for Young Talents of Union Hospital,Tongji Medical College,Huazhong University of Science and Technology(F.W.),NIH/NIDCR grants DE029012 and DE029465Department of Defense Grant PR190899(R.T.F.)Michigan Musculoskeletal Health Core Center(NIH/NIAMS P30 AR069620)。
文摘Bone morphogenetic proteins are essential for bone regeneration/fracture healing but can also induce heterotopic ossification(HO).Understanding accessory factors modulating BMP signaling would provide both a means of enhancing BMP-dependent regeneration while preventing HO.This study focuses on the ability of the collagen receptor,discoidin domain receptor 2(DDR2),to regulate BMP activity.As will be shown,induction of bone formation by subcutaneous BMP2 implants is severely compromised in Ddr2-deficient mice.In addition,Ddr2 deficiency attenuates HO in mice expressing the ACVR1 mutation associated with human fibrodysplasia ossificans progressiva.In cells migrating into BMP2 implants,DDR2 is co-expressed with GLI1,a skeletal stem cell marker,and DDR2/GLI1-positive cells participate in BMP2-induced bone formation where they contribute to chondrogenic and osteogenic lineages.Consistent with this distribution,conditional knockout of Ddr2 in Gli1-expressing cells inhibited bone formation to the same extent seen in globally Ddr2-deficient animals.This response was explained by selective inhibition of Gli1+cell proliferation without changes in apoptosis.The basis for this DDR2 requirement was explored further using bone marrow stromal cells.Although Ddr2 deficiency inhibited BMP2-dependent chondrocyte and osteoblast differentiation and in vivo,bone formation,early BMP responses including SMAD phosphorylation remained largely intact.Instead,Ddr2 deficiency reduced the nuclear/cytoplasmic ratio of the Hippo pathway intermediates,YAP and TAZ.This suggests that DDR2 regulates Hippo pathway-mediated responses to the collagen matrix,which subsequently affect BMP responsiveness.In summary,DDR2 is an important modulator of BMP signaling and a potential therapeutic target both for enhancing regeneration and treating HO.
文摘Spatial memory is crucial for survival within external surroundings and wild environments.The hippocampus,a critical hub for spatial learning and memory formation,has received extensive investigations on how neuromodulators shape its functions(Teixeira et al.,2018;Zhang et al.,2024).However,the landscape of neuromodulations in the hippocampal system remains poorly understood because most studies focus on classical monoamine neuromodulators,such as acetylcholine,serotonin,dopamine,and noradrenaline.The neuropeptides,comprising the most abundant neuromodulators in the central nervous system,play a pivotal role in neural information processing in the hippocampal system.Cholecystokinin(CCK),one of the most abundant neuropeptides,has been implicated in regulating various physiological and neurobiological statuses(Chen et al.,2019).CCK-A receptor(CCK-AR)and CCK-B receptors(CCK-BR)are two key receptors mediating the biological functions of CCK,both of which belong to class-A sevenfold transmembrane G protein-coupled receptors(Nishimura et al.,2015).CCK-AR preferentially reacts to sulfated CCK,whereas CCK-BR binds both CCK and gastrin with similar affinities(Ding et al.,2022).The expression patterns of CCK-AR and CCK-BR are distinct,implying that CCK has various functions in target regions.For instance,CCK-AR is widely expressed in the GI and brain subregions and is hence implicated in the control of digestive function and satiety regulation.Conversely,CCK-BR is abundantly and widely distributed in the central nervous system,which majorly regulates anxiety,learning,and memory(Ding et al.,2022).However,the roles of endogenous CCK and CCK receptors in regulating hippocampal function at electrophysiological and behavioral levels have received less attention.
基金supported by funds from the Italian Ministry of Health,Ricerca Finalizzata,(Grant N.GR-2013-02355882 and GR-2021-12373946 to AL)5x1000 Project of the Istituto Superiore di Sanità(Project code:ISS5x1000_21-949432e8c9be to AL)the European Union–NextGeneration EU through the Italian Ministry of University and Research under PNRR-M4C2-I1.3 Project PE_00000019“HEAL ITALIA”to EA(CUP I83C22001830006)。
文摘Astrocytes,the main population of glial cells in the central nervous system(CNS),exert essential tasks for the control of brain tissue homeostasis,supporting neuron and other glial cell activity from the developmental stage to adult life.To maintain the optimal functionality of the brain,astroglial cells are particularly committed to reacting to every change in tissue homeostatic conditions,from mild modifications of the physiological environment,a process called astrocyte activation,to the more severe alterations occurring in pathological situations causing astrocyte reactivity or reactive astrogliosis(Escartin et al.,2021).During these reactive states,astrocytes mount an active,progressive response encompassing morphological,molecular,and interactional remodeling,leading to the acquisition of new functions and the loss of others,whose intensity,duration,and reversibility are dependent on the nature of the stimulus and regulated in a context-specific manner.
基金National Key RD Program of China Grant(2018YFB1801504)the President Funding of China Academy of Engineering Physics with No.YZJJLX2018009.
文摘In terahertz communication,the direct frequency conversion structure in which orthogonal mixer is the main frequency conversion unit,makes engineers get into trouble of in-phase(I)branch and quadrature(Q)branch imbalance,carrier wave leakage,etc.These damages result in system performance tremendous degrades.We proposed a semiblind method to estimate the I/Q imbalance of THz orthogonal modulator,based on predefined preamble and pilot symbols for quadrature amplitude modulation(QAM).In this paper,a transmitter with Y band quadrature mixer and 20Gbps base-band signal has been tested.The bandwidth of the baseband signal was 7GHz,and the modulation type was 16QAM.By this method,7dB improvement of the system’s symbol Mean Square Error(MSE)has been got.That means the proposed method can be used to eliminate the I/Q imbalance effectively.
基金Project supported by the National Natural Science Foundation of China(Grant No.61108039)the Major Research Plan of the National Natural Science Foundation of China(Grant No.91121023)the Scientific Research Foundation of Graduate School of South China Normal University(Grant No.2012kyjj224)
文摘In a quantum key distribution system, it is crucial to keep the extinction ratio of the coherent pulses stable. This means that the direct current bias point of the electro-optic modulator （EOM） used for generating coherent pulses must be locked. In this paper, an autobias control system based on a lock-in-amplifier for the EOM is introduced. Its drift information extracting theory and control method are analyzed comprehensively. The long term drift of the extinction ratio of the coherent pulses is measured by a single photon detector, which indicates that the autobias control system is effective for stabilizing the bias point of the EOM.
基金supported by the National Natural Science Foundation of China (Grant No. 60878048)the China Postdoctoral Science Foundation (Grant No. 20080440898)
文摘Liquid crystal spatial light modulator （LCSLM） realizing equal-intensity multiple beams often has some features, i.e., phase valley between two adjacent pixels, flybaek region when phase decreases immediately from 2~r to 0, and inevitable backplane curvature, which are different from those of most conventional diffractive optical elements （DOEs）, such as static DOEs. For optimal intensity uniformity, equal-intensity multi-beam generation must be considered for these artifacts. We present a tunable-grating method in which the intensity uniformity can be improved by considering the LCSLM artifacts. For instance, tuning phase modulation depth of the grating, called isosceles triangle multilevel phase grating （ITMPG）, can be used not only to improve the intensity uniformity, but also to fast steer four beams with narrow beamwidths, determined by the same effective aperture of ITMPG. Improved intensity uniformity and high relative diffraction efficiency are demonstrated through experiments with phase-only LCSLM.
文摘A novel technique is proposed for the generation of ultra-wide and flat optical frequency comb(OFC)based on serially cascading three stages of electro absorption modulators(EAMs)through sinusoidal radio frequency(RF)signals by setting frequencies at f GHz,f/2 GHz and f/4 GHz.Here,the first stage acts as subcarrier generator,the second stage acts as subcarrier doubler,and the third stage acts as subcarrier quadrupler.In addition,a higher number of subcarriers can easily be generated by adjusting the driving sinusoidal RF signal.In this paper,cascading three stages of EAMs driven by50 GHz,25 GHz and 12.5 GHz clock sources,we obtain 272 subcarriers with spacing of 2.5 GHz and power deviation within 1 d B.Theoretical analysis of serially cascaded EAMs for subcarrier generation is also investigated.Principal analysis and simulation of this technique are demonstrated.
基金supported partially by the National Natural Science Foundation of China(Nos.62101027 and 61775015)the Fundamental Research Funds for the Central Universities(No.2019JBM010)。
文摘An approach for generating optical frequency comb(OFC)with tunable free spectral range(FSR)is proposed.Two Mach-Zehnder modulators(MZMs)driven by phase-shifted sinusoidal signals are cascaded to generate OFC with plentiful comb lines and the FSR controlled by the drive frequency.Subsequently,a linearly chirped fiber Bragg grating(LCFBG)and a phase modulator(PM)are used to increase the comb FSR by a particular integer multiple.Therefore,by simultaneously controlling the drive frequency of MZMs,the dispersion amount of the LCFBG and the drive signal of the PM,an OFC with desired FSR can be achieved.
