This study investigated the influence of dropwindsonde observations on typhoon forecasts. The study also evaluated the feasibility of the conditional nonlinear optimal perturbation (CNOP) method as a basis for sensiti...This study investigated the influence of dropwindsonde observations on typhoon forecasts. The study also evaluated the feasibility of the conditional nonlinear optimal perturbation (CNOP) method as a basis for sensitivity analysis of such forecasts. This sensitivity analysis could furnish guidance in the selection of targeted observations. The study was performed by conducting observation system experiments (OSEs). This research used the fifth-generation Mesoscale Model (MM5), the Weather Research and Forecasting (WRF) model, and dropsonde observations of Typhoon Nida at 1200 UTC 17 May 2004. The dropsondes were collected under the operational Dropsonde Observations for Typhoon Surveillance near the Taiwan Region (DOTSTAR) program. In this research, five kinds of experiments were designed and conducted:(1) no observations were assimilated; (2) all observations were assimilated;(3) observations in the sensitive area revealed by the CNOP method were assimilated;(4) the same as in (3), but for the region revealed by the first singular vector (FSV) method;and (5) observations within a randomly selected area were assimilated. The OSEs showed that (1) the DOTSTAR data had a positive impact on the forecast of Nida's track;(2) dropsondes in the sensitive areas identified by the MM5 CNOP and FSV remained effective for improving the track forecast for Nida on the WRF platform;and (3) the greatest improvement in the track forecast resulted from the CNOP-based (third) simulation, which indicated that the CNOP method would be useful in decision making about dropsonde deployments.展开更多
With the increasing use of metal foams in various engineering applications, investigation of their dynamic behaviour under varying strain rate is necessary. Closed cell aluminium fly ash foam developed through liquid ...With the increasing use of metal foams in various engineering applications, investigation of their dynamic behaviour under varying strain rate is necessary. Closed cell aluminium fly ash foam developed through liquid metallurgy route was investigated for its stress--strain behaviour at different strain rates ranging from 700 s^-1 to 1950 s^-1. The numerical model of split Hopkinson pressure bar (SHPB) was simulated using commercially available finite element code Abaqus/Explicit. Validation of numerical simulation was carried out using available experimental and numerical results. Full scale stress--strain curves wez'e developed for various strain rates to study the effect of strain rate on compressive strength and energy absorption. The results showed that the closed cell aluminium fly ash foam is sensitive to strain rate.展开更多
The prediction of precipitation depends on accurate modeling of terrestrial transpiration.In recent decades,the trait-based plant hydraulic stress scheme has been developed in land surface models,in order to better pr...The prediction of precipitation depends on accurate modeling of terrestrial transpiration.In recent decades,the trait-based plant hydraulic stress scheme has been developed in land surface models,in order to better predict the hydraulic constraint on terrestrial transpiration.However,the role that each plant functional trait plays in the modeling of transpiration remains unknown.The importance of different plant functional traits for modeled transpiration needs to be addressed.Here,the Morris sensitivity analysis method was implemented in the Common Land Model with the plant hydraulic stress scheme(CoLM-P_(50)HS).Traits related to drought tolerance(P_(50);),stomata,and photosynthesis were screened as the most critical from all 17 plant traits.Among 12 FLUXNET sites,the importance of P_(50);,measured by normalized sensitivity scores,increased towards lower precipitation,whereas the importance of stomatal traits and photosynthetic traits decreased towards drier climate conditions.P_(50);was more important than stomatal traits and photosynthetic traits in arid or semi-arid sites,which implies that hydraulic safety strategies are more crucial than plant growth strategies when plants frequently experience drought.Large variation in drought tolerance traits further proved the coexistence of multiple plant strategies of hydraulic safety.Ignoring the variation in drought tolerance traits may potentially bias the modeling of transpiration.More measurements of drought tolerance traits are therefore necessary to help better represent the diversity of plant hydraulic functions.展开更多
Neuropeptide Y (NPY) is a potent neurotransmitter for feeding. Besides NPY, orexigenic neuropeptides such as agouti-related protein (AgRP), and anorexi- genic neuropeptides such as α-melatonin stimulating hormone (MS...Neuropeptide Y (NPY) is a potent neurotransmitter for feeding. Besides NPY, orexigenic neuropeptides such as agouti-related protein (AgRP), and anorexi- genic neuropeptides such as α-melatonin stimulating hormone (MSH) and cocaine-amphetamine-regulated transcript (CART) are also involved in central feeding regulation. During fasting, NPY and AgRP gene expressions are up-regulated and POMC and CART gene ex- pressions are down-regulated in hypothalamus. Based on the network of peptidergic neurons, the former are involved in positive feeding regulation, and the latter are involved in negative feeding, which exert these feeding-regulated peptides especially in paraventricular nucleus (PVN). To clarify the compensatory mecha- nism of knock-out of NPY system on feeding, change in gene expressions of appetite-related neuropeptides and the feeding behavior was studied in NPY Y5-KO mice. Food intake was increased in Y5-KO mice. Fasting increased the amounts of food and water intake in the KO mice more profoundly. These data indicated the compensatory phenomenon of feeding behavior in Y5-KO mice. RT-PCR and ISH suggested that the compensation of feeding is due to change in gene expressions of AgRP, CART and POMC in hypothalamus. Thus, these fi ndings indicated that the compensatory mechanism involves change in POMC/CART gene expression in arcuate nucleus (ARC). The POMC/CART gene expression is important for central compensatory regulation in feeding behavior.展开更多
Vertical transmission has become the most common mode of transmission of hepatitis C virus (HCV) in children.The rate of perinatal transmission from an HCVinfected mother to her child ranges from 2% to 5% and the prev...Vertical transmission has become the most common mode of transmission of hepatitis C virus (HCV) in children.The rate of perinatal transmission from an HCVinfected mother to her child ranges from 2% to 5% and the prevalence of HCV in children in developed countries ranges between 0.1% and 0.4%.Spontaneous viral clearance seems to be dependent on the genotype and has been reported between 2.4%-25%.For chronically infected patients,treatment with recombinant polyethylene glycol (PEG)-interferon α-2b and daily ribavirin has now been approved as standard treatment for children 2-17 years of age.In five large prospective studies,a total of 318 children and adolescents aged 3-17 years were treated either with subcutaneous PEG-interferon α-2b at a dose of 1-1.5 μg/kg or 60 μg/m2 once a week in combination with oral ribavirin (15 mg/kg per day) or PEG-interferon α-2a with ribavirin.Subjects with genotype 1 and 4 received the medication for 48 wk and individuals with genotype 2 and 3 mainly for 24 wk.Overall sustained viral response (SVR) was achieved in 193/318 (60.7%) of treated patients.Stratified for genotype;120/234 (51%) with genotype 1,68/73 (93%) with genotype 2/3,and 6/11 (55%) with genotype 4 showed SVR.Relapse rate was between 7.7% and 17%.Overall,treatment was well tolerated;how-ever,notable side effects were present in approximately 20%.According to recent experiences in the treatment of chronic hepatitis C in children and adolescents,a combination of PEG-interferon α with ribavirin has been found to be well tolerated and highly efficacious,particularly in individuals with genotype 2/3.Thus,this treatment can be recommended as standard of care until more effective treatment options will become available for genotype 1 patients.展开更多
In this paper, we investigate a two electronic level system with vibrational modes coupled to a Brownian oscillator bath. The difference frequency generation (DFG) signals and sum frequency generation (SFG) signal...In this paper, we investigate a two electronic level system with vibrational modes coupled to a Brownian oscillator bath. The difference frequency generation (DFG) signals and sum frequency generation (SFG) signals are calculated. It is shown that, for the same model, the SFG signals are more sensitive than the DFG signals to the changes of the vibrational modes of the electronic two-level system. Because the SFG conversion efficiency can be improved by using the time-delay method, the findings in this paper predict that the SFG spectrum may probe the changes of the microstructure more effectively.展开更多
The simulations of a heat wave occurring in southern Yangtze-Huaihe valley and southern China during late July,2003 were conducted to examine the sensitivity of simulated surface air temperature(SAT) to different land...The simulations of a heat wave occurring in southern Yangtze-Huaihe valley and southern China during late July,2003 were conducted to examine the sensitivity of simulated surface air temperature(SAT) to different land surface schemes(LSSs) using the Weather Research and Forecasting Model(WRF) Version 2.2 in the short-range mode for 24-h integrations.Initial and boundary conditions employed a National Centers for Environmental Prediction(NCEP) analysis.The results showed that,overall,simulated high-temperature weather is sensitive to different LSSs.Large differences in simulated SAT intensity,threat score,and simulated error under different schemes are identified clearly.In addition,some systematic differences are also in-duced by the LSSs.In terms of threat score from the three LSSs,SLAB is the best,and RUC is better than NOAH.SLAB gives the lowest absolute error for area-averaged SAT,and tends to depict the western Pacific subtropical high with the east-ernmost position at low levels.The LSSs modify the simulated SAT,primarily via the transfer of sensible heat from the land surface to the atmosphere.The physical mechanism of the positive feedback between atmospheric circulation and the SAT is unimportant,with"negative"feedback over most of the simulated areas.This study emphasizes the importance of improving LSSs in SAT forecasting by numerical models.展开更多
By using the global atmospheric general circulation model CAM4.0 including an urban canopy parameterization scheme,the possible impacts of large-scale urbanization in East China on East Asian winter monsoon was invest...By using the global atmospheric general circulation model CAM4.0 including an urban canopy parameterization scheme,the possible impacts of large-scale urbanization in East China on East Asian winter monsoon was investigated via idealized numerical experiments.Results suggest that large-scale urbanization can cause a significant warming effect in both surface temperature and air temperature near the surface over most areas of East China.Meanwhile,large-scale urbanization also alters the surface energy balance,causing evident increases in net surface long-wave radiation and sensible heat flux as well as intensified surface thermal heating to the atmosphere.Forced by the surface thermal heating anomalies induced by the large-scale urban expansion,East Asian winter monsoon circulation exhibits distinct changes.Overall,the extensive urbanization over East China will weaken East Asian winter monsoon,but intensify winter monsoon in northeast China.展开更多
Richardson et al. (Sci Bull, 2015. doi:10.1007/ sl1434-015-0806-z) suggest that the irreducibly simple climate model described in Monckton of Brenchley et al. (Sci Bull 60:122-135, 2015. doi:10.1007/s11434-014- ...Richardson et al. (Sci Bull, 2015. doi:10.1007/ sl1434-015-0806-z) suggest that the irreducibly simple climate model described in Monckton of Brenchley et al. (Sci Bull 60:122-135, 2015. doi:10.1007/s11434-014- 0699-2) was not validated against observations, relying instead on synthetic test data based on underestimated global warming, illogical parameter choice and near-in- stantaneous response at odds with ocean warming and other observations. However, the simple model, informed by its authors' choice of parameters, usually hindcasts observed temperature change more closely than the general-circu- lation models, and finds high climate sensitivity implausi- ble. With IPCC's choice of parameters, the model is further validated in that it duly replicates IPCC's sensitivity interval. Also, fast climate system response is consistent with near-zero or net-negative temperature feedback. Given the large uncertainties in the initial conditions and evolutionary processes determinative of climate sensitivity, subject to obvious caveats a simple sensitivity-focused model need not, and the present model does not, exhibit significantly less predictive skill than the general-circula- tion models.展开更多
基金jointly sponsored by the National Natural Science Foundation of China(Grant No.40830955)the China Meteorological Administration(Grant No.GYHY200906009)
文摘This study investigated the influence of dropwindsonde observations on typhoon forecasts. The study also evaluated the feasibility of the conditional nonlinear optimal perturbation (CNOP) method as a basis for sensitivity analysis of such forecasts. This sensitivity analysis could furnish guidance in the selection of targeted observations. The study was performed by conducting observation system experiments (OSEs). This research used the fifth-generation Mesoscale Model (MM5), the Weather Research and Forecasting (WRF) model, and dropsonde observations of Typhoon Nida at 1200 UTC 17 May 2004. The dropsondes were collected under the operational Dropsonde Observations for Typhoon Surveillance near the Taiwan Region (DOTSTAR) program. In this research, five kinds of experiments were designed and conducted:(1) no observations were assimilated; (2) all observations were assimilated;(3) observations in the sensitive area revealed by the CNOP method were assimilated;(4) the same as in (3), but for the region revealed by the first singular vector (FSV) method;and (5) observations within a randomly selected area were assimilated. The OSEs showed that (1) the DOTSTAR data had a positive impact on the forecast of Nida's track;(2) dropsondes in the sensitive areas identified by the MM5 CNOP and FSV remained effective for improving the track forecast for Nida on the WRF platform;and (3) the greatest improvement in the track forecast resulted from the CNOP-based (third) simulation, which indicated that the CNOP method would be useful in decision making about dropsonde deployments.
文摘With the increasing use of metal foams in various engineering applications, investigation of their dynamic behaviour under varying strain rate is necessary. Closed cell aluminium fly ash foam developed through liquid metallurgy route was investigated for its stress--strain behaviour at different strain rates ranging from 700 s^-1 to 1950 s^-1. The numerical model of split Hopkinson pressure bar (SHPB) was simulated using commercially available finite element code Abaqus/Explicit. Validation of numerical simulation was carried out using available experimental and numerical results. Full scale stress--strain curves wez'e developed for various strain rates to study the effect of strain rate on compressive strength and energy absorption. The results showed that the closed cell aluminium fly ash foam is sensitive to strain rate.
基金funded by the National Natural Science Foundation of China [grant numbers 42088101,42175158,41575072,41730962,41905075,42075158,and U1811464]the National Key Research and Development Program of China [grant numbers 2017YFA0604300 and 2016YFB0200801]supported by the National Key Scientific and Technological Infrastructure project entitled“Earth System Science Numerical Simulator Facility”(Earth-Lab)。
文摘The prediction of precipitation depends on accurate modeling of terrestrial transpiration.In recent decades,the trait-based plant hydraulic stress scheme has been developed in land surface models,in order to better predict the hydraulic constraint on terrestrial transpiration.However,the role that each plant functional trait plays in the modeling of transpiration remains unknown.The importance of different plant functional traits for modeled transpiration needs to be addressed.Here,the Morris sensitivity analysis method was implemented in the Common Land Model with the plant hydraulic stress scheme(CoLM-P_(50)HS).Traits related to drought tolerance(P_(50);),stomata,and photosynthesis were screened as the most critical from all 17 plant traits.Among 12 FLUXNET sites,the importance of P_(50);,measured by normalized sensitivity scores,increased towards lower precipitation,whereas the importance of stomatal traits and photosynthetic traits decreased towards drier climate conditions.P_(50);was more important than stomatal traits and photosynthetic traits in arid or semi-arid sites,which implies that hydraulic safety strategies are more crucial than plant growth strategies when plants frequently experience drought.Large variation in drought tolerance traits further proved the coexistence of multiple plant strategies of hydraulic safety.Ignoring the variation in drought tolerance traits may potentially bias the modeling of transpiration.More measurements of drought tolerance traits are therefore necessary to help better represent the diversity of plant hydraulic functions.
文摘Neuropeptide Y (NPY) is a potent neurotransmitter for feeding. Besides NPY, orexigenic neuropeptides such as agouti-related protein (AgRP), and anorexi- genic neuropeptides such as α-melatonin stimulating hormone (MSH) and cocaine-amphetamine-regulated transcript (CART) are also involved in central feeding regulation. During fasting, NPY and AgRP gene expressions are up-regulated and POMC and CART gene ex- pressions are down-regulated in hypothalamus. Based on the network of peptidergic neurons, the former are involved in positive feeding regulation, and the latter are involved in negative feeding, which exert these feeding-regulated peptides especially in paraventricular nucleus (PVN). To clarify the compensatory mecha- nism of knock-out of NPY system on feeding, change in gene expressions of appetite-related neuropeptides and the feeding behavior was studied in NPY Y5-KO mice. Food intake was increased in Y5-KO mice. Fasting increased the amounts of food and water intake in the KO mice more profoundly. These data indicated the compensatory phenomenon of feeding behavior in Y5-KO mice. RT-PCR and ISH suggested that the compensation of feeding is due to change in gene expressions of AgRP, CART and POMC in hypothalamus. Thus, these fi ndings indicated that the compensatory mechanism involves change in POMC/CART gene expression in arcuate nucleus (ARC). The POMC/CART gene expression is important for central compensatory regulation in feeding behavior.
文摘Vertical transmission has become the most common mode of transmission of hepatitis C virus (HCV) in children.The rate of perinatal transmission from an HCVinfected mother to her child ranges from 2% to 5% and the prevalence of HCV in children in developed countries ranges between 0.1% and 0.4%.Spontaneous viral clearance seems to be dependent on the genotype and has been reported between 2.4%-25%.For chronically infected patients,treatment with recombinant polyethylene glycol (PEG)-interferon α-2b and daily ribavirin has now been approved as standard treatment for children 2-17 years of age.In five large prospective studies,a total of 318 children and adolescents aged 3-17 years were treated either with subcutaneous PEG-interferon α-2b at a dose of 1-1.5 μg/kg or 60 μg/m2 once a week in combination with oral ribavirin (15 mg/kg per day) or PEG-interferon α-2a with ribavirin.Subjects with genotype 1 and 4 received the medication for 48 wk and individuals with genotype 2 and 3 mainly for 24 wk.Overall sustained viral response (SVR) was achieved in 193/318 (60.7%) of treated patients.Stratified for genotype;120/234 (51%) with genotype 1,68/73 (93%) with genotype 2/3,and 6/11 (55%) with genotype 4 showed SVR.Relapse rate was between 7.7% and 17%.Overall,treatment was well tolerated;how-ever,notable side effects were present in approximately 20%.According to recent experiences in the treatment of chronic hepatitis C in children and adolescents,a combination of PEG-interferon α with ribavirin has been found to be well tolerated and highly efficacious,particularly in individuals with genotype 2/3.Thus,this treatment can be recommended as standard of care until more effective treatment options will become available for genotype 1 patients.
基金Supported by the National Natural Science Foundation of China under Grant No. 61078065, Natural Science Foundation of Ningbo City under Grant No. 2008A61009, and K.C. Wong Magna Foundation in Ningbo University
文摘In this paper, we investigate a two electronic level system with vibrational modes coupled to a Brownian oscillator bath. The difference frequency generation (DFG) signals and sum frequency generation (SFG) signals are calculated. It is shown that, for the same model, the SFG signals are more sensitive than the DFG signals to the changes of the vibrational modes of the electronic two-level system. Because the SFG conversion efficiency can be improved by using the time-delay method, the findings in this paper predict that the SFG spectrum may probe the changes of the microstructure more effectively.
基金supported by National Natural Science Foundation of China(Grant No.40875067)part by Knowledge Innovation Program of the Chinese Academy of Sciences(Grant No.IAP09306)
文摘The simulations of a heat wave occurring in southern Yangtze-Huaihe valley and southern China during late July,2003 were conducted to examine the sensitivity of simulated surface air temperature(SAT) to different land surface schemes(LSSs) using the Weather Research and Forecasting Model(WRF) Version 2.2 in the short-range mode for 24-h integrations.Initial and boundary conditions employed a National Centers for Environmental Prediction(NCEP) analysis.The results showed that,overall,simulated high-temperature weather is sensitive to different LSSs.Large differences in simulated SAT intensity,threat score,and simulated error under different schemes are identified clearly.In addition,some systematic differences are also in-duced by the LSSs.In terms of threat score from the three LSSs,SLAB is the best,and RUC is better than NOAH.SLAB gives the lowest absolute error for area-averaged SAT,and tends to depict the western Pacific subtropical high with the east-ernmost position at low levels.The LSSs modify the simulated SAT,primarily via the transfer of sensible heat from the land surface to the atmosphere.The physical mechanism of the positive feedback between atmospheric circulation and the SAT is unimportant,with"negative"feedback over most of the simulated areas.This study emphasizes the importance of improving LSSs in SAT forecasting by numerical models.
基金supported by the National Basic Research Program of China(2010CB428505 and 2011CB952004)Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institu-tions(PAPD)
文摘By using the global atmospheric general circulation model CAM4.0 including an urban canopy parameterization scheme,the possible impacts of large-scale urbanization in East China on East Asian winter monsoon was investigated via idealized numerical experiments.Results suggest that large-scale urbanization can cause a significant warming effect in both surface temperature and air temperature near the surface over most areas of East China.Meanwhile,large-scale urbanization also alters the surface energy balance,causing evident increases in net surface long-wave radiation and sensible heat flux as well as intensified surface thermal heating to the atmosphere.Forced by the surface thermal heating anomalies induced by the large-scale urban expansion,East Asian winter monsoon circulation exhibits distinct changes.Overall,the extensive urbanization over East China will weaken East Asian winter monsoon,but intensify winter monsoon in northeast China.
文摘Richardson et al. (Sci Bull, 2015. doi:10.1007/ sl1434-015-0806-z) suggest that the irreducibly simple climate model described in Monckton of Brenchley et al. (Sci Bull 60:122-135, 2015. doi:10.1007/s11434-014- 0699-2) was not validated against observations, relying instead on synthetic test data based on underestimated global warming, illogical parameter choice and near-in- stantaneous response at odds with ocean warming and other observations. However, the simple model, informed by its authors' choice of parameters, usually hindcasts observed temperature change more closely than the general-circu- lation models, and finds high climate sensitivity implausi- ble. With IPCC's choice of parameters, the model is further validated in that it duly replicates IPCC's sensitivity interval. Also, fast climate system response is consistent with near-zero or net-negative temperature feedback. Given the large uncertainties in the initial conditions and evolutionary processes determinative of climate sensitivity, subject to obvious caveats a simple sensitivity-focused model need not, and the present model does not, exhibit significantly less predictive skill than the general-circula- tion models.