Formamidinium lead bromide(FAPbBr_(3))nanocrystals(NCs)have been considered to be a good optoelectronic material due to their pure green emission,excellent stability and superior carrier transport characteristics.Howe...Formamidinium lead bromide(FAPbBr_(3))nanocrystals(NCs)have been considered to be a good optoelectronic material due to their pure green emission,excellent stability and superior carrier transport characteristics.However,two-photon pumped amplified spontaneous emission(ASE)and the corresponding nonlinear optical properties of FAPbBr_(3) NCs are scarcely revealed.Herein,we synthesized colloidal FAPbBr_(3) NCs with different sizes by changing the molar ratio of FABr/PbBr_(2) in the precursor solution,using ligand assisted precipitation(LARP)technology at room temperature.Photoluminescence(PL)and time resolved photoluminescence(TRPL)spectroscopy were measured to characterize their ASE properties.And their nonlinear optical properties were studied through the Zscan technique and the two-photon excited fluorescence method.The stimulated emission properties including oneand two-photon pumped ASE have been realized from FAPbBr_(3) NCs.With large two-photon absorption coefficient(0.27 cm/GW)and high non-linear absorption cross-section(7.52×10^(5) GM),ASE with threshold as low as 9.8μJ/cm^(2) and 487μJ/cm^(2) have been obtained from colloidal FAPbBr_(3) NCs using one-and two-photon excitations.These results indicate that as a new possible green-emitting frequency-upconversion material with low thresholds,FAPbBr_(3) NCs hold great potential in the development of high-performance two-photon pump lasers.展开更多
With the development of the offshore deep water oil industry many researchers are focusing on the vortex-induced vibrations (VIV) of deep risers. In the present work, Reynolds-averaged Navier-Stokes (RANS) equatio...With the development of the offshore deep water oil industry many researchers are focusing on the vortex-induced vibrations (VIV) of deep risers. In the present work, Reynolds-averaged Navier-Stokes (RANS) equations were combined with the SST κ-ω turbulent model to simulate the stream-wise and transverse motion of an elastically mounted cylinder with a low mass-ratio, a natural frequency ratio of fx/fy = 1 and an Re number between 5 300 and 32 000, The four-order Runge-Kutta method was applied to solve the oscillating equation of the cylinder. The relationship between reduced velocity and parameters of the cylinder, including the lift coefficient, the drag coefficient, displacement and the vortex structure were then compared with recent experimental results and discussed in detail. The present numerical simulation reproduced effects have been observed in experiments, such as the lock-in phenomenon, the hysteretic phenomenon and beating behavior.展开更多
The Paris Agreement marks the beginning of a new era in the global response to climate change, which further clarifies the long-term goal and underlines the urgency addressing climate change. For China,promoting the d...The Paris Agreement marks the beginning of a new era in the global response to climate change, which further clarifies the long-term goal and underlines the urgency addressing climate change. For China,promoting the decoupling between economic growth and carbon emissions as soon as possible is not only the core task of achieving the medium-and long-term goals and strategies to address climate change, but also the inevitable requirement for ensuring the sustainable development of economy and society. Based on the analysis of the historical trends of the economy and social development, as well as society, energy consumption, and key end-use sectors in China, this paper studies the deep carbon emission reduction potential of carbon emission of in energy, industry, building, and transportation and other sectors with "bottom-up" modeling analysis and proposes a medium-and long-term deep decarbonization pathway based on key technologies' mitigation potentials for China. It is found that under deep decarbonization pathway, China will successfully realize the goals set in China's Intended Nationally Determined Contributions of achieving carbon emissions peak around 2030 and lowering carbon dioxide emissions per unit of gross domestic product(GDP) by 60-65% from the 2005 level.From 2030 onward, the development of nonfossil energy will further accelerates, and the share of nonfossil energies in primary energy will amounts to about 44% by 2050. Combined with the acceleration of low-carbon transformation in end-use sectors including industry, building, and transportation, the carbon dioxide emissions in 2050 will fall to the level before 2005, and the carbon dioxide emissions per unit of GDP will decreases by more than 90% from the 2005 level. To ensure the realization of the deep decarbonization pathway, this paper puts forward policy recommendations from four perspectives, including intensifying the total carbon dioxide emissions cap and strengthening the related institutional systems and regulations, improving the incentive policies for industrial lowcarbon development, enhancing the role of the market mechanism, and advocating low-carbon life and consumption patterns.展开更多
Auto-ignition and heat release correlations for controlled auto-ignition(CAI)combustion were derived from extensive in-cylinder pressure data of a four-stroke gasoline engine operating in CAI combustion mode.Abundant ...Auto-ignition and heat release correlations for controlled auto-ignition(CAI)combustion were derived from extensive in-cylinder pressure data of a four-stroke gasoline engine operating in CAI combustion mode.Abundant experiments were carried out under a wide range of air/fuel ratio,speed and residual gas fraction to ensure that the combustion correlations can be used in the entire CAI engine operation range.Furthermore,a more accurate method to compute the residual gas fraction was proposed by calculating the working fluid temperature at the exhaust valve close timing in the experiments.The heat release correlation was described in two parts,one is for the first slower heat release process at low temperature,and the other is for the second faster heat release process at high temperature.Finally the heat release correlation was evaluated on the single cylinder gasoline engine running with CAI combustion by comparing the experimental data with the 1-D engine simulation results obtained with the aid of the GT-Power simulation program.The results show that the predicted loads and ignition timings match closely with the measurements.展开更多
It was the first time demonstrated by us that the number of newborn neurons was increajsed after making lesion in forebraill of adult ring dove (Streptopelia risoria)by means of autoradiography and immunohistochemistr...It was the first time demonstrated by us that the number of newborn neurons was increajsed after making lesion in forebraill of adult ring dove (Streptopelia risoria)by means of autoradiography and immunohistochemistry.Neurogenesis in the adult avian is restricted to the telencephalon. In doves with bilateral electrolytic lesion of nucleus ectostriatum (E), the mean number of proliferating cells in the lateral ventricular zone (LVZ) and newborn neurons in the forebrain increased by 1.95 times and 2.38times respectively as compared with that in intact doves. The most relllarkable increase of neurogenesis induced by nucleus ectostriatum lesions was found at the anteriorposterior level 3 (L3), where the lesion site was located.These results showed that the electrolytic brain lesion altered the distribution pattern of proliferating cells in theLVZ and resulted in increase of the number of newborn neurons in the non-VZ areas of forebrain. The changes in number and distribution pattern of proliferating cells in LVZ and newborn neurons in forebrain may be dependent on site of lesion. Studies on the relationship between proliferating cells in LVZ and newly generated neurons in non-VZ areas may help to understand the mechanism of brain plasticity and development.展开更多
Near 50 years history of the development of radioisotope neutron sources in China is briefly reviewed.The structure design,preparing technology and production status of routine neutron sources including 210Po-Be sourc...Near 50 years history of the development of radioisotope neutron sources in China is briefly reviewed.The structure design,preparing technology and production status of routine neutron sources including 210Po-Be sources,210Po mock fission sources,241Am-Be sources,238Pu-Be sources,252Cf spontaneous fission sources and other special-shape neutron sources are summarized.In addition,the prospects of development on radioisotope neutron source in China are predicted from the needs of nuclear power construction,oil well-logging,neutron moisture gauge and neutron brachytherapy.展开更多
Spontaneous rupture of hepatocellular carcinoma(HCC) is a life-threatening complication and its prognosis is significantly poor because of the high recurrence rate after initial hepatectomy. Resection of isolated extr...Spontaneous rupture of hepatocellular carcinoma(HCC) is a life-threatening complication and its prognosis is significantly poor because of the high recurrence rate after initial hepatectomy. Resection of isolated extrahepatic metastasis of HCC has been advocated to obtain a possibility of long-term survival. However, it is a challenge for clinicians to detect implantation metastasis of spontaneously ruptured HCC. Accurate re-staging plays the most important role in making a decision on isolated metastasis resection. 18F-fluorodeoxyglucose(18F-FDG) positron emission tomography/computed tomography(PET/CT) is useful in detecting intraabdominal implantation metastasis from a variety of malignancies and shows superior accuracy to conventional imaging modalities in determining the location of metastasis. We present one patient with a new isolated pelvic implantation metastasis detected by 18F-FDG PET/CT and pathologically confirmed by PET/CT-guided percutaneous biopsy, who had a history of resection of spontaneously ruptured HCC two years ago. The patient's condition was stable at the 6-mo follow-up after resection of the isolated pelvic metastasis.展开更多
The feasibility of city living with nature as a way to restore the balance between human uses and natural processes is the focus of this paper about the city of Maringa in Southern Brazil. This urban form, a planned n...The feasibility of city living with nature as a way to restore the balance between human uses and natural processes is the focus of this paper about the city of Maringa in Southern Brazil. This urban form, a planned new town founded in 1947 upon a previous, comprehensive British land-development scheme, originally offered a friendly interaction between urban settlement and nature. Hence, this paper outlines how open spaces can be enhanced as an ecological structure, bringing parks, squares, gardens and urban farming into a productive system, both for nature's and for people's sakes. Following a morphological study, the proposed ecological structure will maintain ecological processes within the urban grid and help to preserve historical and social values, by linking a wide variety of natural and restored ecosystems and landscape features. The adoption of this kind of ecological planning will certainly result in an increase of the urban landscape quality, changing actual planning paradigm and preventing the city from environmental quality decrease.展开更多
Objective To observe the sexual differences in electrophysiological properties of neurons in the robust nucleus of the arcopallium (RA) in adult zebra finches, and to provide the direct electrophysiological evidence...Objective To observe the sexual differences in electrophysiological properties of neurons in the robust nucleus of the arcopallium (RA) in adult zebra finches, and to provide the direct electrophysiological evidence for the sexual dimorphism of birdsong. Methods Whole-cell recording was used to record the spontaneous action potential firing rates from RA projection neurons in acute brain slices. Results The projection neurons of RA in male birds fired spontaneously at 10 Hz or above, while in female birds, the frequency was significantly lower, and even no firings could be detected. Conclusion There is a sexual difference in electrophysiological properties of projection neurons in RA, which may result from the difference in the levels of steroid hormones in birds.展开更多
A theoretical model in the 1900 nm waveband for amplified spontaneous emission (ASE) of thulium-doped silica fiber is presented. The ASE spectral power as functions of the fiber length and the pump power is investigat...A theoretical model in the 1900 nm waveband for amplified spontaneous emission (ASE) of thulium-doped silica fiber is presented. The ASE spectral power as functions of the fiber length and the pump power is investigated by solving the rate and propagation equations. By calculation, when the concentration of thulium in fiber is 2.25×1025 m-3, the fiber core diameter is 2.6 μm, and the pump power is 200 mW at 808 nm, the optimal fiber length is 8.1 m, and the output power of ASE can reach 60 mW in the range of 1800-1950 nm with this fiber length. The optical-to-optical conversion is 30.3%. The optimal pump power also can be obtained by this model.展开更多
After the coupling equations of co-pumping,counter-pumping and bidirectional-pumping distributed Raman amplifiers(DRAs) are theoretically analyzed,the power distributions of these three DRAs are acquired with numerica...After the coupling equations of co-pumping,counter-pumping and bidirectional-pumping distributed Raman amplifiers(DRAs) are theoretically analyzed,the power distributions of these three DRAs are acquired with numerical analysis.The performance factors,such as net gain(NG),amplified spontaneous emissions(ASE) noise,double Rayleigh backscattering(DRB) noise,noise figure(NF) and optical signal noise ratio(OSNR),are discussed in depth.It can be found that the NGs of the three DRAs are almost equal.The counter-pumping scheme will induce higher ASE.And the co-pumping DRA has greater DRB noise,but its NF and OSNR are both better than the others'.Furthermore,the relations between signal power and NG,NF,OSNR are also investigated.It is shown that the NF and OSNR of the co-pumping scheme are superior to those of the other two schemes at small input signal power.The above conclusions can play a very important role in guiding the optimum design of DRA.展开更多
Objective: Spontaneous intracranial hypotension (SIH) is recognized far more commonly than ever before. Though usually characterized by low cerebrospinal fluid (CSF) pressure, some patients with SIH are observed ...Objective: Spontaneous intracranial hypotension (SIH) is recognized far more commonly than ever before. Though usually characterized by low cerebrospinal fluid (CSF) pressure, some patients with SIH are observed to have normal pressure values. In this study, we aimed to confirm the proportion of patients with normal CSF opening pressure (CSF OP) and explore the factors affecting CSF OP in SIH patients. Methods: We retrospectively reviewed 206 consecutive SIH patients and analyzed their clinical and imaging variables (including demographic data, body mass index (BMI), duration of symptoms, and brain imaging findings). Univariate and multiVariate analyses were performed to identify the potential factors affecting CSF OP. Results: In a total of 114 (55.3%) cases the CSF OP was 〈60 mmH2O (1 mmH2O=9.80665 Pa), in 90 (43.7%) cases it was between 60 and 200 mmH2O, and in 2 (1.0%) cases it was 〉200 mmH2O. Univadate analysis showed that the duration of symptoms (P〈0.001), BMI (P〈0.001), and age (P=0.024) were positively correlated with CSF OP. However, multivariate analysis suggested that only the duration of symptoms (P〈0.001) and BMI (P〈0.001) were strongly correlated with CSF OP. A relatively high R2 of 0.681 was obtained for the multivariate model. Conclusions: Our study indicated that in patients without a low CSF OP, a diagnosis of SIH should not be excluded. BMI and the duration of symptoms can influence CSF OP in SIH patients, and other potential factors need further investigation.展开更多
An all-optical transient waveform equivalent time sampling system based on cross-gain modulation (XGM) in semiconductor optical amplifier (SOA) is presented. Anoisy SOA dynamic model and PIN equyalent circuit func...An all-optical transient waveform equivalent time sampling system based on cross-gain modulation (XGM) in semiconductor optical amplifier (SOA) is presented. Anoisy SOA dynamic model and PIN equyalent circuit function are employed for system evaluating. The results show this SOA-XGM sampler with subtracting postprocessing can achieve picosecond sampling window. The shape of sampling window can be adjusted by SOA bias current and amplitude of control pulse. Compared with amplified spontaneous emission (ASE) noise of SOA and thermal noise in PIN, the jitter of sampling control pulse causes most sampling error. Simulations show that this SOA-XGM sampler can be a capable candidate for transient waveform sampling.展开更多
文摘Formamidinium lead bromide(FAPbBr_(3))nanocrystals(NCs)have been considered to be a good optoelectronic material due to their pure green emission,excellent stability and superior carrier transport characteristics.However,two-photon pumped amplified spontaneous emission(ASE)and the corresponding nonlinear optical properties of FAPbBr_(3) NCs are scarcely revealed.Herein,we synthesized colloidal FAPbBr_(3) NCs with different sizes by changing the molar ratio of FABr/PbBr_(2) in the precursor solution,using ligand assisted precipitation(LARP)technology at room temperature.Photoluminescence(PL)and time resolved photoluminescence(TRPL)spectroscopy were measured to characterize their ASE properties.And their nonlinear optical properties were studied through the Zscan technique and the two-photon excited fluorescence method.The stimulated emission properties including oneand two-photon pumped ASE have been realized from FAPbBr_(3) NCs.With large two-photon absorption coefficient(0.27 cm/GW)and high non-linear absorption cross-section(7.52×10^(5) GM),ASE with threshold as low as 9.8μJ/cm^(2) and 487μJ/cm^(2) have been obtained from colloidal FAPbBr_(3) NCs using one-and two-photon excitations.These results indicate that as a new possible green-emitting frequency-upconversion material with low thresholds,FAPbBr_(3) NCs hold great potential in the development of high-performance two-photon pump lasers.
文摘With the development of the offshore deep water oil industry many researchers are focusing on the vortex-induced vibrations (VIV) of deep risers. In the present work, Reynolds-averaged Navier-Stokes (RANS) equations were combined with the SST κ-ω turbulent model to simulate the stream-wise and transverse motion of an elastically mounted cylinder with a low mass-ratio, a natural frequency ratio of fx/fy = 1 and an Re number between 5 300 and 32 000, The four-order Runge-Kutta method was applied to solve the oscillating equation of the cylinder. The relationship between reduced velocity and parameters of the cylinder, including the lift coefficient, the drag coefficient, displacement and the vortex structure were then compared with recent experimental results and discussed in detail. The present numerical simulation reproduced effects have been observed in experiments, such as the lock-in phenomenon, the hysteretic phenomenon and beating behavior.
基金supported by The National Key Research and Development Program of China(Grant No.2016YFA0602800)The Pathways to Deep Decarbonization in 2050 ProjectChina's Deep Low Carbon Transition Pathway Research Project
文摘The Paris Agreement marks the beginning of a new era in the global response to climate change, which further clarifies the long-term goal and underlines the urgency addressing climate change. For China,promoting the decoupling between economic growth and carbon emissions as soon as possible is not only the core task of achieving the medium-and long-term goals and strategies to address climate change, but also the inevitable requirement for ensuring the sustainable development of economy and society. Based on the analysis of the historical trends of the economy and social development, as well as society, energy consumption, and key end-use sectors in China, this paper studies the deep carbon emission reduction potential of carbon emission of in energy, industry, building, and transportation and other sectors with "bottom-up" modeling analysis and proposes a medium-and long-term deep decarbonization pathway based on key technologies' mitigation potentials for China. It is found that under deep decarbonization pathway, China will successfully realize the goals set in China's Intended Nationally Determined Contributions of achieving carbon emissions peak around 2030 and lowering carbon dioxide emissions per unit of gross domestic product(GDP) by 60-65% from the 2005 level.From 2030 onward, the development of nonfossil energy will further accelerates, and the share of nonfossil energies in primary energy will amounts to about 44% by 2050. Combined with the acceleration of low-carbon transformation in end-use sectors including industry, building, and transportation, the carbon dioxide emissions in 2050 will fall to the level before 2005, and the carbon dioxide emissions per unit of GDP will decreases by more than 90% from the 2005 level. To ensure the realization of the deep decarbonization pathway, this paper puts forward policy recommendations from four perspectives, including intensifying the total carbon dioxide emissions cap and strengthening the related institutional systems and regulations, improving the incentive policies for industrial lowcarbon development, enhancing the role of the market mechanism, and advocating low-carbon life and consumption patterns.
基金Supported by State Key Project of Fundamental Research Plan(No.2007CB210004).
文摘Auto-ignition and heat release correlations for controlled auto-ignition(CAI)combustion were derived from extensive in-cylinder pressure data of a four-stroke gasoline engine operating in CAI combustion mode.Abundant experiments were carried out under a wide range of air/fuel ratio,speed and residual gas fraction to ensure that the combustion correlations can be used in the entire CAI engine operation range.Furthermore,a more accurate method to compute the residual gas fraction was proposed by calculating the working fluid temperature at the exhaust valve close timing in the experiments.The heat release correlation was described in two parts,one is for the first slower heat release process at low temperature,and the other is for the second faster heat release process at high temperature.Finally the heat release correlation was evaluated on the single cylinder gasoline engine running with CAI combustion by comparing the experimental data with the 1-D engine simulation results obtained with the aid of the GT-Power simulation program.The results show that the predicted loads and ignition timings match closely with the measurements.
文摘It was the first time demonstrated by us that the number of newborn neurons was increajsed after making lesion in forebraill of adult ring dove (Streptopelia risoria)by means of autoradiography and immunohistochemistry.Neurogenesis in the adult avian is restricted to the telencephalon. In doves with bilateral electrolytic lesion of nucleus ectostriatum (E), the mean number of proliferating cells in the lateral ventricular zone (LVZ) and newborn neurons in the forebrain increased by 1.95 times and 2.38times respectively as compared with that in intact doves. The most relllarkable increase of neurogenesis induced by nucleus ectostriatum lesions was found at the anteriorposterior level 3 (L3), where the lesion site was located.These results showed that the electrolytic brain lesion altered the distribution pattern of proliferating cells in theLVZ and resulted in increase of the number of newborn neurons in the non-VZ areas of forebrain. The changes in number and distribution pattern of proliferating cells in LVZ and newborn neurons in forebrain may be dependent on site of lesion. Studies on the relationship between proliferating cells in LVZ and newly generated neurons in non-VZ areas may help to understand the mechanism of brain plasticity and development.
文摘Near 50 years history of the development of radioisotope neutron sources in China is briefly reviewed.The structure design,preparing technology and production status of routine neutron sources including 210Po-Be sources,210Po mock fission sources,241Am-Be sources,238Pu-Be sources,252Cf spontaneous fission sources and other special-shape neutron sources are summarized.In addition,the prospects of development on radioisotope neutron source in China are predicted from the needs of nuclear power construction,oil well-logging,neutron moisture gauge and neutron brachytherapy.
基金Supported by National Science Foundation for Yong Scholars of China,No.81101067
文摘Spontaneous rupture of hepatocellular carcinoma(HCC) is a life-threatening complication and its prognosis is significantly poor because of the high recurrence rate after initial hepatectomy. Resection of isolated extrahepatic metastasis of HCC has been advocated to obtain a possibility of long-term survival. However, it is a challenge for clinicians to detect implantation metastasis of spontaneously ruptured HCC. Accurate re-staging plays the most important role in making a decision on isolated metastasis resection. 18F-fluorodeoxyglucose(18F-FDG) positron emission tomography/computed tomography(PET/CT) is useful in detecting intraabdominal implantation metastasis from a variety of malignancies and shows superior accuracy to conventional imaging modalities in determining the location of metastasis. We present one patient with a new isolated pelvic implantation metastasis detected by 18F-FDG PET/CT and pathologically confirmed by PET/CT-guided percutaneous biopsy, who had a history of resection of spontaneously ruptured HCC two years ago. The patient's condition was stable at the 6-mo follow-up after resection of the isolated pelvic metastasis.
文摘The feasibility of city living with nature as a way to restore the balance between human uses and natural processes is the focus of this paper about the city of Maringa in Southern Brazil. This urban form, a planned new town founded in 1947 upon a previous, comprehensive British land-development scheme, originally offered a friendly interaction between urban settlement and nature. Hence, this paper outlines how open spaces can be enhanced as an ecological structure, bringing parks, squares, gardens and urban farming into a productive system, both for nature's and for people's sakes. Following a morphological study, the proposed ecological structure will maintain ecological processes within the urban grid and help to preserve historical and social values, by linking a wide variety of natural and restored ecosystems and landscape features. The adoption of this kind of ecological planning will certainly result in an increase of the urban landscape quality, changing actual planning paradigm and preventing the city from environmental quality decrease.
基金supported by the National Natural Science Foundation of China (No. 30970363,30570232)the Natural Science Foundation of Guangdong Province, China (No. 05005910)
文摘Objective To observe the sexual differences in electrophysiological properties of neurons in the robust nucleus of the arcopallium (RA) in adult zebra finches, and to provide the direct electrophysiological evidence for the sexual dimorphism of birdsong. Methods Whole-cell recording was used to record the spontaneous action potential firing rates from RA projection neurons in acute brain slices. Results The projection neurons of RA in male birds fired spontaneously at 10 Hz or above, while in female birds, the frequency was significantly lower, and even no firings could be detected. Conclusion There is a sexual difference in electrophysiological properties of projection neurons in RA, which may result from the difference in the levels of steroid hormones in birds.
基金supported by the National Natural Science Foundation of China (No.60677027)Research Fund for the Doctoral Program of Higher Education of China (No.20060422025)+2 种基金Natural Science Foundation of Shandong Province of China (No.2006ZRC01022)Science Fund for Distinguished Young Scholars of Shandong Province of China (No.2008JQB01155)Research Award Fund for Outstanding Middle-aged and Young Scientist of Shandong Province of China (No.2007BS08003)
文摘A theoretical model in the 1900 nm waveband for amplified spontaneous emission (ASE) of thulium-doped silica fiber is presented. The ASE spectral power as functions of the fiber length and the pump power is investigated by solving the rate and propagation equations. By calculation, when the concentration of thulium in fiber is 2.25×1025 m-3, the fiber core diameter is 2.6 μm, and the pump power is 200 mW at 808 nm, the optimal fiber length is 8.1 m, and the output power of ASE can reach 60 mW in the range of 1800-1950 nm with this fiber length. The optical-to-optical conversion is 30.3%. The optimal pump power also can be obtained by this model.
基金supported by the National Natural Science Foundation of China (Nos.60907041,61003256 and 61071117)the Natural Science Foundation of CQ CSTC (No.2010BB2409)
文摘After the coupling equations of co-pumping,counter-pumping and bidirectional-pumping distributed Raman amplifiers(DRAs) are theoretically analyzed,the power distributions of these three DRAs are acquired with numerical analysis.The performance factors,such as net gain(NG),amplified spontaneous emissions(ASE) noise,double Rayleigh backscattering(DRB) noise,noise figure(NF) and optical signal noise ratio(OSNR),are discussed in depth.It can be found that the NGs of the three DRAs are almost equal.The counter-pumping scheme will induce higher ASE.And the co-pumping DRA has greater DRB noise,but its NF and OSNR are both better than the others'.Furthermore,the relations between signal power and NG,NF,OSNR are also investigated.It is shown that the NF and OSNR of the co-pumping scheme are superior to those of the other two schemes at small input signal power.The above conclusions can play a very important role in guiding the optimum design of DRA.
文摘Objective: Spontaneous intracranial hypotension (SIH) is recognized far more commonly than ever before. Though usually characterized by low cerebrospinal fluid (CSF) pressure, some patients with SIH are observed to have normal pressure values. In this study, we aimed to confirm the proportion of patients with normal CSF opening pressure (CSF OP) and explore the factors affecting CSF OP in SIH patients. Methods: We retrospectively reviewed 206 consecutive SIH patients and analyzed their clinical and imaging variables (including demographic data, body mass index (BMI), duration of symptoms, and brain imaging findings). Univariate and multiVariate analyses were performed to identify the potential factors affecting CSF OP. Results: In a total of 114 (55.3%) cases the CSF OP was 〈60 mmH2O (1 mmH2O=9.80665 Pa), in 90 (43.7%) cases it was between 60 and 200 mmH2O, and in 2 (1.0%) cases it was 〉200 mmH2O. Univadate analysis showed that the duration of symptoms (P〈0.001), BMI (P〈0.001), and age (P=0.024) were positively correlated with CSF OP. However, multivariate analysis suggested that only the duration of symptoms (P〈0.001) and BMI (P〈0.001) were strongly correlated with CSF OP. A relatively high R2 of 0.681 was obtained for the multivariate model. Conclusions: Our study indicated that in patients without a low CSF OP, a diagnosis of SIH should not be excluded. BMI and the duration of symptoms can influence CSF OP in SIH patients, and other potential factors need further investigation.
基金supported by the National Natural Science Foundation of China(No.61077068)the Science and Technology Commission of Shanghai Municipality(STCSM)(No.08DZ2231100)
文摘An all-optical transient waveform equivalent time sampling system based on cross-gain modulation (XGM) in semiconductor optical amplifier (SOA) is presented. Anoisy SOA dynamic model and PIN equyalent circuit function are employed for system evaluating. The results show this SOA-XGM sampler with subtracting postprocessing can achieve picosecond sampling window. The shape of sampling window can be adjusted by SOA bias current and amplitude of control pulse. Compared with amplified spontaneous emission (ASE) noise of SOA and thermal noise in PIN, the jitter of sampling control pulse causes most sampling error. Simulations show that this SOA-XGM sampler can be a capable candidate for transient waveform sampling.