In August 2024,the United Nations General Assembly adopted resolution 78/321 to declare the period from 2025 to 2034 as the“Decade of Action for Cryospheric Sciences”.This action was championed by the Republic of Fr...In August 2024,the United Nations General Assembly adopted resolution 78/321 to declare the period from 2025 to 2034 as the“Decade of Action for Cryospheric Sciences”.This action was championed by the Republic of France and the Republic of Tajikistan,with support from over 30 member states,underscoring the urgent need for an international scientific collaboration to mitigate the far-reaching effects of cryospheric changes on ecosystems,water security,and global climate stability.A dedicated brainstorming session during the March 2025 celebrations in Paris convened over 1,000 policymakers,scientists,and stakeholders to outline the priorities for the Decade of Action.The session aimed to foster cross-border partnerships and strengthen the integration of cryospheric science into global climate adaptation strategies.Joint task force teams developed an integrated governance framework through discussions across five domains—scientific research,socioeconomic impacts,education,policy advocacy,and finance.The Decade of Action for Cryospheric Sciences represents a critical shift from observation to intervention,mobilizing global stakeholders to translate scientific consensus into concrete measures against cryosphere decline.The initiative responds to urgent calls from UNESCO and international partners for coordinated action on cryosphere preservation.展开更多
In this paper, a novel Medium Access Control (MAC) protocol for industrial Wireless Local Area Networks (WLANs) is proposed and studied. The main challenge in industry automation systems is the ultra-low network laten...In this paper, a novel Medium Access Control (MAC) protocol for industrial Wireless Local Area Networks (WLANs) is proposed and studied. The main challenge in industry automation systems is the ultra-low network latency with a target upper bound in the order of 1 ms while maintaining high network reliability and availability. The novelty of the proposed wireless MAC protocol resides in its similar latency performance as its counterpart in wired industrial LAN. First, the functional design of the MAC protocol is introduced. Then its performance results gained from hardware implementation (SystemC and VHDL) on an FPGA platform are presented. Finally, a real-time communication module which achieves the ultra-low latency required in industrial automation is described.展开更多
AIM To assess magnetic resonance imaging(MRI)and faecal calprotectin to detect endoscopic postoperative recurrence in patients with Crohn's disease(CD).METHODS From two tertiary centers,all patients with CD who un...AIM To assess magnetic resonance imaging(MRI)and faecal calprotectin to detect endoscopic postoperative recurrence in patients with Crohn's disease(CD).METHODS From two tertiary centers,all patients with CD who underwent ileocolonic resection were consecutively and prospectively included.All the patients underwent MRI and endoscopy within the first year after surgery or after the restoration of intestinal continuity[median=6 mo(5.0-9.3)].The stools were collected the day before the colonoscopy to evaluate faecal calprotectin level.Endoscopic postoperative recurrence(POR)was defined as Rutgeerts'index≥i2b.The MRI was analyzed independently by two radiologists blinded from clinical data.RESULTS Apparent diffusion coefficient(ADC)was lower in patients with endoscopic POR compared to those with no recurrence(2.03±0.32 vs 2.27±0.38×10^(-3)mm^2/s,P=0.032).Clermont score(10.4±5.8 vs 7.4±4.5,P=0.038)and relative contrast enhancement(RCE)(129.4%±62.8%vs 76.4%±32.6%,P=0.007)were significantly associated with endoscopic POR contrary to the magnetic resonance index of activity(Ma RIA)(7.3±4.5 vs 4.8±3.7;P=0.15)and MR scoring system(P=0.056).ADC<2.35×10^(-3)mm^2/s[sensitivity=0.85,specificity=0.65,positive predictive value(PPV)=0.85,negative predictive value(NPV)=0.65]and RCE>100%(sensitivity=0.75,specificity=0.81,PPV=0.75,NPV=0.81)were the best cutoff values to identify endoscopic POR.Clermont score>6.4(sensitivity=0.61,specificity=0.82,PPV=0.73,NPV=0.74),Ma RIA>3.76(sensitivity=0.61,specificity=0.82,PPV=0.73,NPV=0.74)and a MR scoring system≥MR1(sensitivity=0.54,specificity=0.82,PPV=0.70,and NPV=0.70)demonstrated interesting performances to detect endoscopic POR.Faecal calprotectin values were significantly higher in patients with endoscopic POR(114±54.5μg/g vs 354.8±432.5μg/g;P=0.0075).Faecal calprotectin>100μg/g demonstrated high performances to detect endoscopic POR(sensitivity=0.67,specificity=0.93,PPV=0.89 and NPV=0.77).CONCLUSION Faecal calprotectin and MRI are two reliable tools to detect endoscopic POR in patients with CD.展开更多
Objective: Previous reports from our laboratory have described short-latency contractions in muscles of the distal upper limb following stimulation of lower limb nerves or skin in persons with injury to the cervical s...Objective: Previous reports from our laboratory have described short-latency contractions in muscles of the distal upper limb following stimulation of lower limb nerves or skin in persons with injury to the cervical spinal cord. It takes 6 or more months for interlimb reflexes (ILR) to appear following acute spinal cord injury (SCI), suggesting they might be due to new synaptic interconnections between lower limb sensory afferents and motoneurons in the cervical enlargemen t. In this study, we asked if once formed, the strength of these synaptic connec tions increased over time, a finding that would be consistent with the above hyp othesis. Methods: We studied persons with sub-acute and/or chronic cervical SCI . ILR were elicited by brief trains of electrical pulses applied to the skin ove rlying the tibial nerve atthe back of the knee. Responses were quantified based on their presence or absence in different upper limb muscles. We also generated peri-stimulus time histograms for single motor unitresponse latency, probabilit y, and peak duration. Comparisons of these parameters were made in subjects at s ub-acute versus chronic stages post-injury. Results: In persons with sub-acut e SCI, the probability of seeing ILR in a given muscle of the forearm or hand wa s low at first, but increased substantially over the next 1-2 years. Motor unit responses at this sub-acute stage had a prolonged and variable latency, with a lower absolute response probability, compared to findings from subjects with ch ronic (i.e. stable) SCI. Conclusions: Our findings demonstrate that interlimb re flex activity, once established after SCI,shows signs of strengthening synaptic contacts between afferentand efferent components, consistent with ongoing synapt ic plasticity. Significance: Neurons within the adult human spinal cord caudal t o a lesion site are not static, but appear to be capable of developing novel-ye t highly efficacious-synaptic contacts following trauma-induced partial denerv ation. In this case, such contacts between ascending afferents and cervical moto neurons do not appear to provide any functional benefit to the subject. In fact their presence may limit the regenerative effort of supraspinal pathways which o riginally innervated these motoneurons, should effort in animal models to promot e regeneration across the lesion epicenter be successfully translated to humans with chronic SCI.展开更多
The G-WADI network by UNESCO promotes the global capacity for management of water resources in arid and semi-arid areas. The primary aim has been to build a comprehensive global network to promote regional and interna...The G-WADI network by UNESCO promotes the global capacity for management of water resources in arid and semi-arid areas. The primary aim has been to build a comprehensive global network to promote regional and international cooperation so as to in- crease knowledge and improve management practices through the sharing of information. The G-WADI objectives and achieve- ments of the past 10 years are reviewed. A number of key initiatives have been implemented^the formation of five regional net- works, the creation of a central G-WADI web site, promotion of near-real-time rainfall distribution software enhanced by the in- clusion of satellite based precipitation estimations, as well as workshop and web-based activities on chemical and isotopic tracers and on rain water harvesting. Two workshops on surface and on groundwater modeling, supported by publications have been held in India and China. The Asian G-WADI network remains very active, but activities in the other three regions are developing （Af- rica, Arab Region, Latin America and the Caribbean）.展开更多
Germanium tin(GeSn)is a group IV semiconductor with a direct band-to-band transition below 0.8 eV.Nonequilibrium GeSn alloys up to 20%Sn content were realized with low temperature(160℃)molecular beam epitaxy.Photodet...Germanium tin(GeSn)is a group IV semiconductor with a direct band-to-band transition below 0.8 eV.Nonequilibrium GeSn alloys up to 20%Sn content were realized with low temperature(160℃)molecular beam epitaxy.Photodetectors and light emitting diodes(LEDs)were realized from in situ doped pin junctions in GeSn on Ge virtual substrates.The detection wavelength for infrared radiation was extended to 2μm with clear potential for further extension into the mid-infrared.GeSn LEDs with Sn content of up to 4%exhibit light emission from the direct band transition,although GeSn with low Sn content is an indirect semiconductor.The photon emission energies span the region between 0.81 and 0.65 eV.Optical characterization techniques such as ellipsometry,in situ reflectometry,and Raman spectroscopy were used to monitor the Sn incorporation in GeSn epitaxy.展开更多
Upcoming generations of coherent intra/inter data center interconnects currently lack a clear path toward a reduction of cost and power consumption,which are the driving factors for these data links.In this work,the t...Upcoming generations of coherent intra/inter data center interconnects currently lack a clear path toward a reduction of cost and power consumption,which are the driving factors for these data links.In this work,the tradeoffs associated with a transition from coherent C-band to O-band silicon photonics are addressed and evaluated.The discussion includes the fundamental components of coherent data links,namely the optical components,fiber link and transceivers.As a major component of these links,a monolithic silicon photonic BiCMOS O-band coherent receiver is evaluated for its potential performance and compared to an analogous C-band device.展开更多
A 2 nd transconductance subharmonic receiver for 245 GHz spectroscopy sensor applications has been proposed. The receiver consists of a 245 GHz on-chip folded dipole antenna, a CB（common base） LNA, a 2 nd transcondu...A 2 nd transconductance subharmonic receiver for 245 GHz spectroscopy sensor applications has been proposed. The receiver consists of a 245 GHz on-chip folded dipole antenna, a CB（common base） LNA, a 2 nd transconductance SHM（subharmonic mixer）, and a 120 GHz push-push VCO with 1/64 divider. The receiver is fabricated in f;/f;= 300/500 GHz SiGe:C BiCMOS technology. The receiver dissipates a low power of 288 mW.Integrated with the on-chip antenna, the receiver is measured on-chip with a conversion gain of 15 dB, a bandwidth of 15 GHz, and the chip will be utilized in PCB board design for gas spectroscopy sensor application.展开更多
We demonstrate an integrated Si optical single-sideband(OSSB) modulator composed of a parallel dual-ring modulator(PDRM) and a quadrature hybrid coupler(QHC). Both the PDRM and the QHC are carefully designed for 30 GH...We demonstrate an integrated Si optical single-sideband(OSSB) modulator composed of a parallel dual-ring modulator(PDRM) and a quadrature hybrid coupler(QHC). Both the PDRM and the QHC are carefully designed for 30 GHz opearation, and their operations are verified by measurement. The Si OSSB modulator successfully generates a single sideband with larger than 15 dB suppression of the undesired sideband.展开更多
We present an accurate, easy-to-use large-signal SPICE circuit model for depletion-type silicon ring modulators(Si RMs). Our model includes both the electrical and optical characteristics of the Si RM and consists of ...We present an accurate, easy-to-use large-signal SPICE circuit model for depletion-type silicon ring modulators(Si RMs). Our model includes both the electrical and optical characteristics of the Si RM and consists of circuit elements whose values change depending on modulation voltages. The accuracy of our model is confirmed by comparing the SPICE simulation results of 25 Gb/s non-return-to-zero(NRZ) modulation with the measurement. The model is used for performance optimization of monolithically integrated Si photonic NRZ and pulse-amplitudemodulation 4 transmitters in the standard SPICE circuit design environment.展开更多
Germanium （Ge） pin photodiodes show clear direct band gap emission at room temperature, as grown on bulk silicon in both photoluminescence （PL） and electro- luminescence （EL）. PL stems from the top contact layer...Germanium （Ge） pin photodiodes show clear direct band gap emission at room temperature, as grown on bulk silicon in both photoluminescence （PL） and electro- luminescence （EL）. PL stems from the top contact layer with highly doped Ge because of strong absorption of visible laser light excitation （532 nm）. EL stems from the recombination of injected carriers in the undoped intrinsic layer. The difference in peak positions for PL （0.73 eV） and EL （0.80 eV） is explained by band gap narrowing from high doping in n＋-top layer. A superlinear increase of EL with current density is explained by a rising ratio of direct/ indirect electron densities when quasi Fermi energy level rises into the conduction band. An analytical model for the direct/indirect electron density ratio is given using simplifying assumptions.展开更多
We demonstrate a silicon electronic–photonic integrated 25 Gb/s nonreturn-to-zero transmitter that includes driver circuits,depletion-type Si ring modulator,Ge photodetector,temperature sensor,on-chip heater,and temp...We demonstrate a silicon electronic–photonic integrated 25 Gb/s nonreturn-to-zero transmitter that includes driver circuits,depletion-type Si ring modulator,Ge photodetector,temperature sensor,on-chip heater,and temperature controller,all monolithically integrated on a 0.25μm photonic BiCMOS technology platform.The integrated transmitter successfully provides stable and optimal 25 Gb/s modulation characteristics against external temperature fluctuation.展开更多
A polarization-diversity loop with a silicon waveguide with a lateral p-i-n diode as a nonlinear medium is used to realize polarization insensitive four-wave mixing. Wavelength conversion of seven dual-polarization 16...A polarization-diversity loop with a silicon waveguide with a lateral p-i-n diode as a nonlinear medium is used to realize polarization insensitive four-wave mixing. Wavelength conversion of seven dual-polarization 16-quadrature amplitude modulation(QAM) signals at 16 GBd is demonstrated with an optical signal-to-noise ratio penalty below 0.7 dB. High-quality converted signals are generated thanks to the low polarization dependence(≤0.5 dB) and the high conversion efficiency(CE) achievable. The strong Kerr nonlinearity in silicon and the decrease of detrimental free-carrier absorption due to the reverse-biased p-i-n diode are key in ensuring high CE levels.展开更多
In this paper,we report on polarization combining two-dimensional grating couplers(2D GCs)on amorphous Si:H,fabricated in the backend of line of a photonic BiCMOS platform.The 2D GCs can be used as an interface of a h...In this paper,we report on polarization combining two-dimensional grating couplers(2D GCs)on amorphous Si:H,fabricated in the backend of line of a photonic BiCMOS platform.The 2D GCs can be used as an interface of a hybrid silicon photonic coherent transmitter,which can be implemented on bulk Si wafers.The fabricated 2D GCs operate in the telecom C-band and show an experimental coupling efficiency of−5 dB with a wafer variation of±1.2 dB.Possibilities for efficiency enhancement and improved performance stability in future design generations are outlined and extension toward O-band devices is also investigated.展开更多
Background Urogenital schistosomiasis is endemic in Mali and is a major cause of serious morbidity in large parts of the world.This disease is responsible for many socio-economic and public health issues.The aim of th...Background Urogenital schistosomiasis is endemic in Mali and is a major cause of serious morbidity in large parts of the world.This disease is responsible for many socio-economic and public health issues.The aim of this study was to investigate the impact of the disease on morbidity and to describe demographic and socioeconomic factors in relation to the status of children with urogenital schistosomiasis in Mali.Methods We conducted a cross-sectional study in November 2021 of 971 children aged 6 to 14 years selected at random from six schools in three districts in the Kayes Region of Mali.Demographic and socioeconomic data were collected on survey forms.Clinical data were collected following a medical consultation.Hematuria was systematically searched for through the use of strips.The search for Schistosoma haematobium eggs in urine was done via the filtration method.The urinary tract was examined by ultrasound.Associations between each of these variables and disease infection were tested using multivariate logistic regression.Results The overall prevalence of urinary schistosomiasis detected was 50.2%.The average intensity of infection was 36 eggs/10 ml of urine.The associated risk factors for urogenital schistosomiasis showed that children who bathed,used the river/pond as a domestic water source,and who habitually urinated in the river/pond were more affected(P<0.05).Children with farming parents were most affected(P=0.032).The collection of clinical signs revealed that boys had more pollakiuria(58.6%)and dysuria(46.4%)than girls.Ultrasound data showed that focal lesion rates were recorded in all villages with the lowest rate in Diakalel(56.1%).Ultrasound and parasitological findings showed that irregularity and thickening were strongly associated with urinary schistosomiasis(P<0.0001).Conclusions Schistosoma haematobium infection was still endemic in the study site despite more than a decade of mass treatment with praziquantel.However,the high percentage of symptoms associated with high intensity reinforces the idea that further studies in terms of schistosomiasis-related morbidity are still needed.展开更多
基金support from USA NSF Grant OPP2213875NASA Grant 80NSSC22K1707.
文摘In August 2024,the United Nations General Assembly adopted resolution 78/321 to declare the period from 2025 to 2034 as the“Decade of Action for Cryospheric Sciences”.This action was championed by the Republic of France and the Republic of Tajikistan,with support from over 30 member states,underscoring the urgent need for an international scientific collaboration to mitigate the far-reaching effects of cryospheric changes on ecosystems,water security,and global climate stability.A dedicated brainstorming session during the March 2025 celebrations in Paris convened over 1,000 policymakers,scientists,and stakeholders to outline the priorities for the Decade of Action.The session aimed to foster cross-border partnerships and strengthen the integration of cryospheric science into global climate adaptation strategies.Joint task force teams developed an integrated governance framework through discussions across five domains—scientific research,socioeconomic impacts,education,policy advocacy,and finance.The Decade of Action for Cryospheric Sciences represents a critical shift from observation to intervention,mobilizing global stakeholders to translate scientific consensus into concrete measures against cryosphere decline.The initiative responds to urgent calls from UNESCO and international partners for coordinated action on cryosphere preservation.
基金funding from the German Federal Ministry for Education and Research(2015-2017)under the grant agreement No.16KIS0179 also referred as DEAL
文摘In this paper, a novel Medium Access Control (MAC) protocol for industrial Wireless Local Area Networks (WLANs) is proposed and studied. The main challenge in industry automation systems is the ultra-low network latency with a target upper bound in the order of 1 ms while maintaining high network reliability and availability. The novelty of the proposed wireless MAC protocol resides in its similar latency performance as its counterpart in wired industrial LAN. First, the functional design of the MAC protocol is introduced. Then its performance results gained from hardware implementation (SystemC and VHDL) on an FPGA platform are presented. Finally, a real-time communication module which achieves the ultra-low latency required in industrial automation is described.
文摘AIM To assess magnetic resonance imaging(MRI)and faecal calprotectin to detect endoscopic postoperative recurrence in patients with Crohn's disease(CD).METHODS From two tertiary centers,all patients with CD who underwent ileocolonic resection were consecutively and prospectively included.All the patients underwent MRI and endoscopy within the first year after surgery or after the restoration of intestinal continuity[median=6 mo(5.0-9.3)].The stools were collected the day before the colonoscopy to evaluate faecal calprotectin level.Endoscopic postoperative recurrence(POR)was defined as Rutgeerts'index≥i2b.The MRI was analyzed independently by two radiologists blinded from clinical data.RESULTS Apparent diffusion coefficient(ADC)was lower in patients with endoscopic POR compared to those with no recurrence(2.03±0.32 vs 2.27±0.38×10^(-3)mm^2/s,P=0.032).Clermont score(10.4±5.8 vs 7.4±4.5,P=0.038)and relative contrast enhancement(RCE)(129.4%±62.8%vs 76.4%±32.6%,P=0.007)were significantly associated with endoscopic POR contrary to the magnetic resonance index of activity(Ma RIA)(7.3±4.5 vs 4.8±3.7;P=0.15)and MR scoring system(P=0.056).ADC<2.35×10^(-3)mm^2/s[sensitivity=0.85,specificity=0.65,positive predictive value(PPV)=0.85,negative predictive value(NPV)=0.65]and RCE>100%(sensitivity=0.75,specificity=0.81,PPV=0.75,NPV=0.81)were the best cutoff values to identify endoscopic POR.Clermont score>6.4(sensitivity=0.61,specificity=0.82,PPV=0.73,NPV=0.74),Ma RIA>3.76(sensitivity=0.61,specificity=0.82,PPV=0.73,NPV=0.74)and a MR scoring system≥MR1(sensitivity=0.54,specificity=0.82,PPV=0.70,and NPV=0.70)demonstrated interesting performances to detect endoscopic POR.Faecal calprotectin values were significantly higher in patients with endoscopic POR(114±54.5μg/g vs 354.8±432.5μg/g;P=0.0075).Faecal calprotectin>100μg/g demonstrated high performances to detect endoscopic POR(sensitivity=0.67,specificity=0.93,PPV=0.89 and NPV=0.77).CONCLUSION Faecal calprotectin and MRI are two reliable tools to detect endoscopic POR in patients with CD.
文摘Objective: Previous reports from our laboratory have described short-latency contractions in muscles of the distal upper limb following stimulation of lower limb nerves or skin in persons with injury to the cervical spinal cord. It takes 6 or more months for interlimb reflexes (ILR) to appear following acute spinal cord injury (SCI), suggesting they might be due to new synaptic interconnections between lower limb sensory afferents and motoneurons in the cervical enlargemen t. In this study, we asked if once formed, the strength of these synaptic connec tions increased over time, a finding that would be consistent with the above hyp othesis. Methods: We studied persons with sub-acute and/or chronic cervical SCI . ILR were elicited by brief trains of electrical pulses applied to the skin ove rlying the tibial nerve atthe back of the knee. Responses were quantified based on their presence or absence in different upper limb muscles. We also generated peri-stimulus time histograms for single motor unitresponse latency, probabilit y, and peak duration. Comparisons of these parameters were made in subjects at s ub-acute versus chronic stages post-injury. Results: In persons with sub-acut e SCI, the probability of seeing ILR in a given muscle of the forearm or hand wa s low at first, but increased substantially over the next 1-2 years. Motor unit responses at this sub-acute stage had a prolonged and variable latency, with a lower absolute response probability, compared to findings from subjects with ch ronic (i.e. stable) SCI. Conclusions: Our findings demonstrate that interlimb re flex activity, once established after SCI,shows signs of strengthening synaptic contacts between afferentand efferent components, consistent with ongoing synapt ic plasticity. Significance: Neurons within the adult human spinal cord caudal t o a lesion site are not static, but appear to be capable of developing novel-ye t highly efficacious-synaptic contacts following trauma-induced partial denerv ation. In this case, such contacts between ascending afferents and cervical moto neurons do not appear to provide any functional benefit to the subject. In fact their presence may limit the regenerative effort of supraspinal pathways which o riginally innervated these motoneurons, should effort in animal models to promot e regeneration across the lesion epicenter be successfully translated to humans with chronic SCI.
文摘The G-WADI network by UNESCO promotes the global capacity for management of water resources in arid and semi-arid areas. The primary aim has been to build a comprehensive global network to promote regional and international cooperation so as to in- crease knowledge and improve management practices through the sharing of information. The G-WADI objectives and achieve- ments of the past 10 years are reviewed. A number of key initiatives have been implemented^the formation of five regional net- works, the creation of a central G-WADI web site, promotion of near-real-time rainfall distribution software enhanced by the in- clusion of satellite based precipitation estimations, as well as workshop and web-based activities on chemical and isotopic tracers and on rain water harvesting. Two workshops on surface and on groundwater modeling, supported by publications have been held in India and China. The Asian G-WADI network remains very active, but activities in the other three regions are developing （Af- rica, Arab Region, Latin America and the Caribbean）.
文摘Germanium tin(GeSn)is a group IV semiconductor with a direct band-to-band transition below 0.8 eV.Nonequilibrium GeSn alloys up to 20%Sn content were realized with low temperature(160℃)molecular beam epitaxy.Photodetectors and light emitting diodes(LEDs)were realized from in situ doped pin junctions in GeSn on Ge virtual substrates.The detection wavelength for infrared radiation was extended to 2μm with clear potential for further extension into the mid-infrared.GeSn LEDs with Sn content of up to 4%exhibit light emission from the direct band transition,although GeSn with low Sn content is an indirect semiconductor.The photon emission energies span the region between 0.81 and 0.65 eV.Optical characterization techniques such as ellipsometry,in situ reflectometry,and Raman spectroscopy were used to monitor the Sn incorporation in GeSn epitaxy.
基金the GermanResearch Foundation (DFG) through the projects EPIC-Sense (ZI 1283-6-1)and EPIDAC (ZI 1283-7-1)the Federal Ministry of Education andResearch (BMBF) through project PEARLS (13N14932)the EuropeanCommission through project H2020-SPACE-ORIONAS (822002).
文摘Upcoming generations of coherent intra/inter data center interconnects currently lack a clear path toward a reduction of cost and power consumption,which are the driving factors for these data links.In this work,the tradeoffs associated with a transition from coherent C-band to O-band silicon photonics are addressed and evaluated.The discussion includes the fundamental components of coherent data links,namely the optical components,fiber link and transceivers.As a major component of these links,a monolithic silicon photonic BiCMOS O-band coherent receiver is evaluated for its potential performance and compared to an analogous C-band device.
基金Project supported by the Zhejiang National Natural Science Foundation of China(No.LQ17F040001)the Key Laboratory Open Project Fund of Southeast University,China(No.K201817)
文摘A 2 nd transconductance subharmonic receiver for 245 GHz spectroscopy sensor applications has been proposed. The receiver consists of a 245 GHz on-chip folded dipole antenna, a CB（common base） LNA, a 2 nd transconductance SHM（subharmonic mixer）, and a 120 GHz push-push VCO with 1/64 divider. The receiver is fabricated in f;/f;= 300/500 GHz SiGe:C BiCMOS technology. The receiver dissipates a low power of 288 mW.Integrated with the on-chip antenna, the receiver is measured on-chip with a conversion gain of 15 dB, a bandwidth of 15 GHz, and the chip will be utilized in PCB board design for gas spectroscopy sensor application.
基金Korean Ministry of Science,ICT and Future Planning(MSIP)(2015R1A2A2A01007772)Korean Ministry of Trade,Industry and Energy(MOTIE)(10065666)
文摘We demonstrate an integrated Si optical single-sideband(OSSB) modulator composed of a parallel dual-ring modulator(PDRM) and a quadrature hybrid coupler(QHC). Both the PDRM and the QHC are carefully designed for 30 GHz opearation, and their operations are verified by measurement. The Si OSSB modulator successfully generates a single sideband with larger than 15 dB suppression of the undesired sideband.
基金Ministry of Trade,Industry and Energy(MOTIE)(10065666)Yonsei University(Research Scholarship Grants)IC Design Education Center(IDEC)
文摘We present an accurate, easy-to-use large-signal SPICE circuit model for depletion-type silicon ring modulators(Si RMs). Our model includes both the electrical and optical characteristics of the Si RM and consists of circuit elements whose values change depending on modulation voltages. The accuracy of our model is confirmed by comparing the SPICE simulation results of 25 Gb/s non-return-to-zero(NRZ) modulation with the measurement. The model is used for performance optimization of monolithically integrated Si photonic NRZ and pulse-amplitudemodulation 4 transmitters in the standard SPICE circuit design environment.
文摘Germanium （Ge） pin photodiodes show clear direct band gap emission at room temperature, as grown on bulk silicon in both photoluminescence （PL） and electro- luminescence （EL）. PL stems from the top contact layer with highly doped Ge because of strong absorption of visible laser light excitation （532 nm）. EL stems from the recombination of injected carriers in the undoped intrinsic layer. The difference in peak positions for PL （0.73 eV） and EL （0.80 eV） is explained by band gap narrowing from high doping in n＋-top layer. A superlinear increase of EL with current density is explained by a rising ratio of direct/ indirect electron densities when quasi Fermi energy level rises into the conduction band. An analytical model for the direct/indirect electron density ratio is given using simplifying assumptions.
基金Ministry of Trade,Industry and Energy(10065666)National Research Foundation of Korea(2020R1A2C201508911)Yonsei University.
文摘We demonstrate a silicon electronic–photonic integrated 25 Gb/s nonreturn-to-zero transmitter that includes driver circuits,depletion-type Si ring modulator,Ge photodetector,temperature sensor,on-chip heater,and temperature controller,all monolithically integrated on a 0.25μm photonic BiCMOS technology platform.The integrated transmitter successfully provides stable and optimal 25 Gb/s modulation characteristics against external temperature fluctuation.
文摘A polarization-diversity loop with a silicon waveguide with a lateral p-i-n diode as a nonlinear medium is used to realize polarization insensitive four-wave mixing. Wavelength conversion of seven dual-polarization 16-quadrature amplitude modulation(QAM) signals at 16 GBd is demonstrated with an optical signal-to-noise ratio penalty below 0.7 dB. High-quality converted signals are generated thanks to the low polarization dependence(≤0.5 dB) and the high conversion efficiency(CE) achievable. The strong Kerr nonlinearity in silicon and the decrease of detrimental free-carrier absorption due to the reverse-biased p-i-n diode are key in ensuring high CE levels.
基金This work was supported in part by the German Research Foundation(DFG)through the projects EPIC-Sense(ZI 1283-6-1)EPIDAC(ZI 1283-7-1)the Federal Ministry of Education and Research(BMBF)through project PEARLS(13N14932).
文摘In this paper,we report on polarization combining two-dimensional grating couplers(2D GCs)on amorphous Si:H,fabricated in the backend of line of a photonic BiCMOS platform.The 2D GCs can be used as an interface of a hybrid silicon photonic coherent transmitter,which can be implemented on bulk Si wafers.The fabricated 2D GCs operate in the telecom C-band and show an experimental coupling efficiency of−5 dB with a wafer variation of±1.2 dB.Possibilities for efficiency enhancement and improved performance stability in future design generations are outlined and extension toward O-band devices is also investigated.
文摘Background Urogenital schistosomiasis is endemic in Mali and is a major cause of serious morbidity in large parts of the world.This disease is responsible for many socio-economic and public health issues.The aim of this study was to investigate the impact of the disease on morbidity and to describe demographic and socioeconomic factors in relation to the status of children with urogenital schistosomiasis in Mali.Methods We conducted a cross-sectional study in November 2021 of 971 children aged 6 to 14 years selected at random from six schools in three districts in the Kayes Region of Mali.Demographic and socioeconomic data were collected on survey forms.Clinical data were collected following a medical consultation.Hematuria was systematically searched for through the use of strips.The search for Schistosoma haematobium eggs in urine was done via the filtration method.The urinary tract was examined by ultrasound.Associations between each of these variables and disease infection were tested using multivariate logistic regression.Results The overall prevalence of urinary schistosomiasis detected was 50.2%.The average intensity of infection was 36 eggs/10 ml of urine.The associated risk factors for urogenital schistosomiasis showed that children who bathed,used the river/pond as a domestic water source,and who habitually urinated in the river/pond were more affected(P<0.05).Children with farming parents were most affected(P=0.032).The collection of clinical signs revealed that boys had more pollakiuria(58.6%)and dysuria(46.4%)than girls.Ultrasound data showed that focal lesion rates were recorded in all villages with the lowest rate in Diakalel(56.1%).Ultrasound and parasitological findings showed that irregularity and thickening were strongly associated with urinary schistosomiasis(P<0.0001).Conclusions Schistosoma haematobium infection was still endemic in the study site despite more than a decade of mass treatment with praziquantel.However,the high percentage of symptoms associated with high intensity reinforces the idea that further studies in terms of schistosomiasis-related morbidity are still needed.
