Background:Balance impairment is one of the strongest risk factors for falls.Proprioception,cutaneous sensitivity,and muscle strength are 3 important contributors to balance control in older adults.The relationship th...Background:Balance impairment is one of the strongest risk factors for falls.Proprioception,cutaneous sensitivity,and muscle strength are 3 important contributors to balance control in older adults.The relationship that dynamic and static balance control has to proprioception,cutaneous sensitivity,and muscle strength is still unclear.This study was performed to investigate the relationship these contributors have to dynamic and static balance control.Methods:A total of 164 older adults(female=89,left dominant=15,age:73.5±7.8 years,height:161.6±7.1 cm,weight:63.7±8.9 kg,mean±SD)participated in this study.It tested the proprioception of their knee flexion/extension and ankle dorsi/plantarflexion,along with cutaneous sensitivity at the great toe,first and fifth metatarsals,arch,and heel,and the muscle strength of their ankle dorsi/plantarflexion and hip abduction.The Berg Balance Scale(BBS)and the root mean square(RMS)of the center of pressure(CoP)were collected as indications of dynamic and static balance control.A partial correlation was used to determine the relationship between the measured outcomes variables(BBS and CoPRMS)and the proprioception,cutaneous sensitivity,and muscle strength variables.Results:Proprioception of ankle plantarflexion(r=-0.306,p=0.002)and dorsiflexion(r=-0.217,p=0.030),and muscle strength of ankle plantarflexion(r=0.275,p=0.004),dorsiflexion(r=0.369,p<0.001),and hip abduction(r=0.342,p<0.001)were weakly to moderately correlated with BBS.Proprioception of ankle dorsiflexion(r=0.218,p=0.020)and cutaneous sensitivity at the great toe(r=0.231,p=0.041)and arch(r=0.285,p=0.002)were weakly correlated with CoP-RMS in the anteroposterior direction.Proprioception of ankle dorsiflexion(r=0.220,p=0.035),knee flexion(r=0.308,p=0.001)and extension(r=0.193,p=0.040),and cutaneous sensitivity at the arch(r=0.206,p=0.028)were weakly to moderately correlated with CoP-RMS in the mediolateral direction.Conclusion:There is a weak-to-moderate relationship between proprioception and dynamic and static balance control,a weak relationship between cutaneous sensitivity and static balance control,and a weak-to-moderate relationship between muscle strength and dynamic balance control.展开更多
Irregular surface flattening,which is based on a boundary conforming grid and the transformation between curvilinear and Cartesian coordinate systems,is a mathematical method that can elegantly handle irregular surfac...Irregular surface flattening,which is based on a boundary conforming grid and the transformation between curvilinear and Cartesian coordinate systems,is a mathematical method that can elegantly handle irregular surfaces,but has been limited to obtaining first arrivals only.By combining a multistage scheme with the fast-sweeping method(FSM,the method to obtain first-arrival traveltime in curvilinear coordinates),the reflected waves from a crustal interface can be traced in a topographic model,in which the reflected wavefront is obtained by reinitializing traveltimes in the interface for upwind branches.A local triangulation is applied to make a connection between velocity and interface nodes.Then a joint inversion of first-arrival and reflection traveltimes for imaging seismic velocity structures in complex terrains is presented.Numerical examples all perform well with different seismic velocity models.The increasing topographic complexity and even use of a high curvature reflector in these models demonstrate the reliability,accuracy and robustness of the new working scheme;checkerboard testing illustrates the method's high resolution.Noise tolerance testing indicates the method's ability to yield practical traveltime tomography.Further development of the multistage scheme will allow other later arrivals to be traced and used in the traveltime inversion.展开更多
Objective: To compare the transferring efficiency and killing effects of one time and continuous mediation with GE7, a non-viral targeted delivery system, in transfection of thymidine kinase gene of herpes simplex vi...Objective: To compare the transferring efficiency and killing effects of one time and continuous mediation with GE7, a non-viral targeted delivery system, in transfection of thymidine kinase gene of herpes simplex virus (HSV-tk) into ovarian cancer cells. Methods: GE7 was used to prepare recombinants with β-galactosidase (β-gal) and HSVI-tk; the recombinants were then used to transfect human ovarian cancer line CaOV3 once and continuously. β-gal staining was used to compare the efficiencies of one time and continuous mediation with GE7 system. Ganciclovior (GCV) was introduced into HSVI-tk transfected ovarian cells. Through drawing the cell growth curve and flow cytometry, the killing effects of GCV on once and continuously GE7/HSVI-tk transfected cells were observed. Results: We found that the one time and continuous exogenous gene transfer efficiencies were about 80% and 85%, respectively. When 1 μg/mL GCV was used to treat ovarian cell transfected with HSVI-tk gene, growth inhibiting rates of ovarian cells of one time and continuous transferring were 82% and 90%, respectively; their apoptosis indices were 15 and 30, respectively. Under same GCV concentration, continuous mediation of GE7/pCMV-tk transfection into ovarian cancer cells had more significant inhibitory effect than one time mediation (P 〈 0.05). Conclusion: Compared with one time mediation, continuous mediation of transfection with GE7 gene delivery system has higher efficiency. Continuous mediation of GE7/HSVI-tk/GCV therapeutic gene system has more powerful killing effect.展开更多
The installation of wind energy has increased rapidly around the world. The grid codes about the wind energy require wind turbine (WT) has the ability of fault (or low voltage) ride-through (FRT). To study the FRT ope...The installation of wind energy has increased rapidly around the world. The grid codes about the wind energy require wind turbine (WT) has the ability of fault (or low voltage) ride-through (FRT). To study the FRT operation of the wind farms, three methods were discussed. First, the rotor short current of doubly-fed induction generator (DFIG) was limited by introducing a rotor side protection circuit. Second, the voltage of DC bus was limited by a DC energy absorb circuit. Third, STATCOM was used to increase the low level voltages of the wind farm. Simulation under MATLAB was studied and the corresponding results were given and discussed. The methods proposed in this paper can limit the rotor short current and the DC voltage of the DFIG WT to some degree, but the voltage support to the power system during the fault largely depend on the installation place of STATCOM.展开更多
The complex interactions were performed among non-pharmaceutical interventions,vaccinations,and hosts for all epidemics in China's Mainland during the spread of COVID-19.Specially,the small-scale epidemic in the c...The complex interactions were performed among non-pharmaceutical interventions,vaccinations,and hosts for all epidemics in China's Mainland during the spread of COVID-19.Specially,the small-scale epidemic in the city described by SVEIR model was less found in the current studies.The SVEIR model with control was established to analyze the dynamical and epidemiological features of two epidemics in Jinzhou City led by Omicron variants before and after Twenty Measures.In this study,the total population(N)of Jinzhou City was divided into five compartments:the susceptible(S),the vaccinated(V),the exposed(E),the infected(I),and the recovered(R).By surveillance data and the SVEIR model,three methods(maximum likelihood method,exponential growth rate method,next generation matrix method)were governed to estimate basic reproduction number,and the results showed that an increasing tendency of basic reproduction number from Omicron BA.5.2 to Omicron BA.2.12.1.Meanwhile,the effective reproduction number for two epidemics were investigated by surveillance data,and the results showed that Jinzhou wave 1 reached the peak on November 1 and was controlled 7 days later,and that Jinzhou wave 2 reached the peak on November 28 and was controlled 5 days later.Moreover,the impacts of non-pharmaceutical interventions(awareness delay,peak delay,control intensity)were discussed extensively,the variations of infection scales for Omicron variant and EG.5 variant were also discussed.Furthermore,the investigations on peaks and infection scales for two epidemics in dynamic zero-COVID policy were operated by the SVEIR model with control.The investigations on public medical requirements of Jinzhou City and Liaoning Province were analyzed by using SVEIR model without control,which provided a possible perspective on variant evolution in the future.展开更多
采用包埋法制备了粒径均匀的海藻酸钙(CA)硝化菌小球,并用不同浓度的NaCl溶液处理CA硝化菌小球来改善其扩散传质性能,以N-异丙基丙烯酰胺(NIPAAm)、丙烯酸(AA)为单体材料,形成温度/pH响应层,制得一种新型温度/pH双响应硝化菌凝胶小球。...采用包埋法制备了粒径均匀的海藻酸钙(CA)硝化菌小球,并用不同浓度的NaCl溶液处理CA硝化菌小球来改善其扩散传质性能,以N-异丙基丙烯酰胺(NIPAAm)、丙烯酸(AA)为单体材料,形成温度/pH响应层,制得一种新型温度/pH双响应硝化菌凝胶小球。以NH_(4)^(+)-N为指示物考察不同制备条件下硝化菌凝胶小球的氨氮去除性能及对温度、pH的敏感特性,并将其应用于实际废水的脱氮处理。结果表明,经浓度为0.3%的NaCl溶液改性后的CA硝化菌小球的扩散传质性能最佳;15 m L温度响应溶液中NIPAAm为200 mg、MBA为4 mg,10 mL pH响应溶液中AA为200 mg、MBA为4 mg时双响应硝化菌小球的氨氮去除性能最好;当温度低至4℃时,氨氮去除率可达29.45%,当pH为9时,氨氮去除率仍可达35.48%。双响应硝化菌凝胶小球具有良好的温度、pH敏感特性,对实际废水中氨氮的去除也具有良好效果,有利于提高低温及碱性条件下硝化菌的硝化效果。展开更多
Heterosis is a fundamental biological phenomenon characterized by the superior performance of hybrids over their parents.Although tremendous progress has been reported in seed crops,the molecular mechanisms underlying...Heterosis is a fundamental biological phenomenon characterized by the superior performance of hybrids over their parents.Although tremendous progress has been reported in seed crops,the molecular mechanisms underlying heterosis in clonally propagated crops are largely unknown.Potato(Solanum tuberosum L.)is the most important tuber crop and an ongoing revolution is transforming potato from a clonally propagated tetraploid crop into a seed-propagated diploidhybrid potato.In our previous study,we developed the first generation of highly homozygous inbred lines of potato and hybrids with strong heterosis.Here,we integrated transcriptome,metabolome,and DNA methylation data to explore the genetic and molecular basis of potato heterosis at three developmental stages.We found that the initial establishment of heterosis in diploid potato was mainly due to dominant complementation.Flower color,male fertility,and starch and sucrose metabolism showed obvious gene dominant complementation in hybrids,and hybrids devoted more energy to primary metabolism for rapid growth.In addition,we identified~2700 allele-specific expression genes at each stage,which likely function in potato heterosis and might be regulated by CHH allele-specific methylation level.Our multi-omics analysis provides insight into heterosis in potato and facilitates the exploitation of heterosis in potato breeding.展开更多
In plants, post-transcriptional gene silencing(PTGS) protects the genome from foreign genes and restricts the expression of certain endogenous genes for proper development. Here, we review the recent progress about ho...In plants, post-transcriptional gene silencing(PTGS) protects the genome from foreign genes and restricts the expression of certain endogenous genes for proper development. Here, we review the recent progress about how the unwanted PTGS is avoided in plants. As a decision-making step of PTGS, aberrant transcripts from most endogenous coding genes are strictly sorted to the bidirectional RNA decay pathways in cytoplasm but not to the short interference RNA(si RNA)-mediated PTGS, with the exception of a few development-relevant endogenous si RNA-producing genes. We also discuss a finely balanced PTGS threshold model that plants fully take advantage of the power of PTGS without self-harm.展开更多
Background:A COVID-19 outbreak in the rural areas of Shijiazhuang City was attributed to the complex interactions among vaccination,host,and non-pharmaceutical interventions(NPIs).Herein,we investigated the epidemiolo...Background:A COVID-19 outbreak in the rural areas of Shijiazhuang City was attributed to the complex interactions among vaccination,host,and non-pharmaceutical interventions(NPIs).Herein,we investigated the epidemiological characteristics of all reported symptomatic cases by picking Shijiazhuang City,Hebei Province in Northern China as research objective.In addition,we established an age-group mathematical model to perform the optimal fitting and to investigate the dynamical profiles under three scenarios.Methods:All reported symptomatic cases of Shijiazhuang epidemic(January 2-February 3,2021)were investigated in our study.The cases were classified by gender,age group and location,the distributions were analyzed by epidemiological characteristics.Furthermore,the reported data from Health Commission of Hebei Province was also analyzed by using an age-group mathematical model by two phases and three scenarios.Results:Shijiazhuang epidemic caused by SARS-CoV-2 wild strain was recorded with the peak 84 cases out of 868 reported symptomatic cases on January 11,2021,which was implemented with strong NPIs by local government and referred as baseline situation in this study.The research results showed that R0 under baseline situation ranged from 4.47 to 7.72,and Rt of Gaocheng Distinct took 3.72 with 95%confidence interval from 3.23 to 4.35 on January 9,the declining tendencies of Rt under baseline situation were kept till February 3,the value of Rt reached below 1 on January 19 and remained low value up to February 3 for Gaocheng District and Shijiazhuang City during Shijiazhuang epidemic.This indicated Shijiazhuang epidemic was under control on January 19.However,if the strong NPIs were kept,but remote isolation operated on January 11 was not implemented as of February 9,then the scale of Shijiazhuang epidemic reached 9,482 cases from age group who were 60 years old and over out of 31,017 symptomatic cases.The investigation also revealed that Shijiazhuang epidemic reached 132,648 symptomatic cases for age group who were 60 years old and over(short for G2)under risk-based strategies(Scenario A),58,048 symptomatic cases for G2 under late quarantine strategies(Scenario B)and 207,124 symptomatic cases for G2 under late quarantine double risk strategies(Scenario C),and that the corresponding transmission tendencies of Rt for three scenarios were consistently controlled on Jan 29,2021.Compared with baseline situation,the dates for controlling Rt below 1 under three scenarios were delayed 10 days.Conclusions:Shijiazhuang epidemic was the first COVID-19 outbreak in the rural areas in Hebei Province of Northern China.The targeted interventions adopted in early 2021 were effective to halt the transmission due to the implementation of a strict and village-wide closure.However we found that age group profile and NPIs played critical rules to successfully contain Shijiazhuang epidemic,which should be considered by public health policies in rural areas of China's Mainland during the dynamic zero-COVID policy.展开更多
The intrusion events in the optical fiber pre-warning system (OFPS) are divided into two types which are harmful intrusion event and harmless interference event. At present, the signal feature extraction methods of ...The intrusion events in the optical fiber pre-warning system (OFPS) are divided into two types which are harmful intrusion event and harmless interference event. At present, the signal feature extraction methods of these two types of events are usually designed from the view of the time domain. However, the differences of time-domain characteristics for different harmful intrusion events are not obvious, which cannot reflect the diversity of them in detail. We find that the spectrum distribution of different intrusion signals has obvious differences. For this reason, the intrusion signal is transformed into the frequency domain. In this paper, an energy ratio feature extraction method of harmful intrusion event is drawn on. Firstly, the intrusion signals are pre-processed and the power spectral density (PSD) is calculated. Then, the energy ratio of different frequency bands is calculated, and the corresponding feature vector of each type of intrusion event is further formed. The linear discriminant analysis (LDA) classifier is used to identify the harmful intrusion events in the paper. Experimental results show that the algorithm improves the recognition rate of the intrusion signal, and further verifies the feasibility and validity of the algorithm.展开更多
The World Health Organization(WHO)declared monkeypox as a public health emergency of international concern(PHEIC)on July 23,2022,their highest level of alert.This raised concerns about the management of the global mon...The World Health Organization(WHO)declared monkeypox as a public health emergency of international concern(PHEIC)on July 23,2022,their highest level of alert.This raised concerns about the management of the global monkeypox outbreak,as well as the scientific analysis and accurate prediction of the future course of the epidemic.This study used EpiSIX(an analysis and prediction system for epidemics based on a general SEIR model)to analyze the monkeypox epidemic and to forecast the major tendencies based on data from the USA CDC(https://www.cdc.gov)and the WHO(https://www.who.int/health-topics/monkeypox).The global outbreak of monkeypox started in the UK on May 2,2022,which marked the beginning of an epidemic wave.As of October 28,2022,the cumulative number of reported cases worldwide was 77,115,with 36 deaths.EpiSIX simulations predict that the global monkeypox epidemic will enter a low epidemic status on March 1,2023 with the cumulative number of confirmed cases ranging from 85,000 to 124,000,and the total number of deaths ranging from 60 to 87.Our analysis revealed that the basic reproduction number(R0)of monkeypox virus(MPXV)is near to 3.1 and the percentage of asymptomatic individuals is 13.1%–14.5%,both of which are similar to the data for SARS.The vaccination efficiency against susceptibility(VEs)of individuals who have had monkeypox is~79%,and the vaccination efficiency against infectiousness(VEi)of individuals who have had monkeypox is~76%–82%.The mean incubation period for monkeypox is 8 days.In total,94.7%of infected individuals develop symptoms within 20 days and recover within 2 weeks after the confirmation of symptoms.Simulation results using EpiSIX showed that ring vaccination was remarkably effective against monkeypox.Our findings confirmed that a 20-day isolation for close contacts is necessary.展开更多
This paper reports the effects of shear force on anoxic granular sludge in sequencing batch reactors (SBR). The study was carried out in two SBRs (SBR1 and SBR2) in which sodium acetate (200mg COD·L^-1) was...This paper reports the effects of shear force on anoxic granular sludge in sequencing batch reactors (SBR). The study was carried out in two SBRs (SBR1 and SBR2) in which sodium acetate (200mg COD·L^-1) was used as the sole substrate and sodium nitrate (40 mgNO3-N·L^-1) was employed as the electron acceptor. The preliminary objective of this study was to cultivate anoxic granules in the SBR in order to investigate the effects of shear force on the formation of anoxic granular sludge and to compare the properties of anoxic sludge in the SBR. This study reports new results for the values of average velocity gradient, a measure of the applied shear force, which was varied in the two SBRs (3.79 s^-1 and 9.76 s^-1 for SBR1 and SBR2 respectively). The important findings of this research highlight the dual effects of shear force on anoxic granules. A low shear force can produce large anoxic granules with high activity and poor settling ability, whereas higher shear forces produce smaller granules with better settling ability and lower activity. The results of this study show that the anoxic granulation is closely related to the strength of the shear force. For high shear force, this research demonstrated that: 1) granules with smaller diameters, high density and good settling ability were formed in the reactor, and 2) granular sludge formed faster than it did in the low shear force reactor (41days versus 76 days). Once a steady-state has been achieved, the nitrate and COD removal rates were found to be 98% and 80%, respectively. For low shear force, such as was applied in SBR1, this research demonstrated that: 1) the activity of anoxic granular sludge in low shear force was higher than that in high shear force, 2) higher amount of soluble microbial products (SMPs) were produced, and 3) large pores were observed inside the larger granules,which are beneficial for nitrogen gas diffusion. Electron microscopic examination of the anoxic granules in both reactors showed that the morphology of the granules was ellipsoidal with a clear outline. Coccus and rod-shaped bacteria were wrapped by filamentous bacteria on the surface of granule.展开更多
Anoxic granular sludge was developed in a laboratory-scale sequencing batch reactor which was fed with sodium acetate and sodium nitrate as electron donor and accepter. The sludge in the reactor was almost granulated ...Anoxic granular sludge was developed in a laboratory-scale sequencing batch reactor which was fed with sodium acetate and sodium nitrate as electron donor and accepter. The sludge in the reactor was almost granulated after approximately 90 days of cultivation. In the present study, a detailed examination of surface morphology and internal structure of anoxic granular sludge was conducted using scanning electron microscope. It showed that the bacteria inside the granules had a uniform, coccus-like shape. By contrast, filamentous bacteria were predominant outside the granules. These bacteria were woven and had wrapped the coccus bacteria together to form granules. The small amounts of DO in the liquid bulk promoted the growth of filamentous bacteria on the surface of the granules. A string-bag hypothesis was proposed to elucidate the structure and formation of the anoxic granular sludge. It suggested that micro-aeration could be a method to promote granulation in practical anoxic treatment systems.展开更多
This paper investigates the relationship between intra-regional accessibility and economic development within the Cardiff City Region. Embracing the Capital City of Cardiff and its hinterland, this region is regarded ...This paper investigates the relationship between intra-regional accessibility and economic development within the Cardiff City Region. Embracing the Capital City of Cardiff and its hinterland, this region is regarded as the economically most important one in Wales, and the key driver of Wale's current and future economic prosperity. Therefore, it is a significant problem how to fully realize its economic potential and its national role, and it is also controversial whether poor intra-regional accessibility is the biggest barrier to its further growth. This has been debated for years and provoked great research interest. By using a qualitative methodology, the paper identifi es that intra-regional accessibility is necessary, though not suff icient, for economic growth. It is necessary since it can increase the productivity of economic activities and infl uence the fi rms' location behavior, based on which this paper proposes some recommendations for economic development.展开更多
The prediction system EpiSIX was used to study the COVID-19 epidemic in China's Mainland between November 2022 and January 2023,based on reported data from December 9,2022,to January 30,2023,released by The Chines...The prediction system EpiSIX was used to study the COVID-19 epidemic in China's Mainland between November 2022 and January 2023,based on reported data from December 9,2022,to January 30,2023,released by The Chinese Center for Disease Control and Prevention on February 1,2023.Three kinds of reported data were used for model fitting:the daily numbers of positive nucleic acid tests and deaths,and the daily number of hospital beds taken by COVID-19 patients.It was estimated that the overall infection rate was 87.54%and the overall case fatality rate was 0.078%–0.116%(median 0.100%).Assuming that a new COVID-19 epidemic outbreak would start in March or April of 2023,induced by a slightly more infectious mutant strain,we predicted a possible large rebound between September and October 2023,with a peak demand of between 800,000 and 900,000 inpatient beds.If no such new outbreak was induced by other variants,then the current COVID-19 epidemic course in China's Mainland would remain under control until the end of 2023.However,it is suggested that the necessary medical resources be prepared to manage possible COVID-19 epidemic emergencies in the near future,especially for the period between September and October 2023.展开更多
基金funded by Shandong Province Youth Innovative Talent Induction Program(grant number 2019-183)the National Key R&D Program of China(2018YFC2000600).
文摘Background:Balance impairment is one of the strongest risk factors for falls.Proprioception,cutaneous sensitivity,and muscle strength are 3 important contributors to balance control in older adults.The relationship that dynamic and static balance control has to proprioception,cutaneous sensitivity,and muscle strength is still unclear.This study was performed to investigate the relationship these contributors have to dynamic and static balance control.Methods:A total of 164 older adults(female=89,left dominant=15,age:73.5±7.8 years,height:161.6±7.1 cm,weight:63.7±8.9 kg,mean±SD)participated in this study.It tested the proprioception of their knee flexion/extension and ankle dorsi/plantarflexion,along with cutaneous sensitivity at the great toe,first and fifth metatarsals,arch,and heel,and the muscle strength of their ankle dorsi/plantarflexion and hip abduction.The Berg Balance Scale(BBS)and the root mean square(RMS)of the center of pressure(CoP)were collected as indications of dynamic and static balance control.A partial correlation was used to determine the relationship between the measured outcomes variables(BBS and CoPRMS)and the proprioception,cutaneous sensitivity,and muscle strength variables.Results:Proprioception of ankle plantarflexion(r=-0.306,p=0.002)and dorsiflexion(r=-0.217,p=0.030),and muscle strength of ankle plantarflexion(r=0.275,p=0.004),dorsiflexion(r=0.369,p<0.001),and hip abduction(r=0.342,p<0.001)were weakly to moderately correlated with BBS.Proprioception of ankle dorsiflexion(r=0.218,p=0.020)and cutaneous sensitivity at the great toe(r=0.231,p=0.041)and arch(r=0.285,p=0.002)were weakly correlated with CoP-RMS in the anteroposterior direction.Proprioception of ankle dorsiflexion(r=0.220,p=0.035),knee flexion(r=0.308,p=0.001)and extension(r=0.193,p=0.040),and cutaneous sensitivity at the arch(r=0.206,p=0.028)were weakly to moderately correlated with CoP-RMS in the mediolateral direction.Conclusion:There is a weak-to-moderate relationship between proprioception and dynamic and static balance control,a weak relationship between cutaneous sensitivity and static balance control,and a weak-to-moderate relationship between muscle strength and dynamic balance control.
基金financial support for this work contributed by the National Key Research and Development Program of China(grant nos.2016YFC0600302,2016YFC0600101 and 2016YFC0600201)the National Natural Science Foundation of China(grants 41604075,41430213,41574092 and 41474068)
文摘Irregular surface flattening,which is based on a boundary conforming grid and the transformation between curvilinear and Cartesian coordinate systems,is a mathematical method that can elegantly handle irregular surfaces,but has been limited to obtaining first arrivals only.By combining a multistage scheme with the fast-sweeping method(FSM,the method to obtain first-arrival traveltime in curvilinear coordinates),the reflected waves from a crustal interface can be traced in a topographic model,in which the reflected wavefront is obtained by reinitializing traveltimes in the interface for upwind branches.A local triangulation is applied to make a connection between velocity and interface nodes.Then a joint inversion of first-arrival and reflection traveltimes for imaging seismic velocity structures in complex terrains is presented.Numerical examples all perform well with different seismic velocity models.The increasing topographic complexity and even use of a high curvature reflector in these models demonstrate the reliability,accuracy and robustness of the new working scheme;checkerboard testing illustrates the method's high resolution.Noise tolerance testing indicates the method's ability to yield practical traveltime tomography.Further development of the multistage scheme will allow other later arrivals to be traced and used in the traveltime inversion.
基金a grant from the National Natural Sciences Foundation of China (No 39800144)
文摘Objective: To compare the transferring efficiency and killing effects of one time and continuous mediation with GE7, a non-viral targeted delivery system, in transfection of thymidine kinase gene of herpes simplex virus (HSV-tk) into ovarian cancer cells. Methods: GE7 was used to prepare recombinants with β-galactosidase (β-gal) and HSVI-tk; the recombinants were then used to transfect human ovarian cancer line CaOV3 once and continuously. β-gal staining was used to compare the efficiencies of one time and continuous mediation with GE7 system. Ganciclovior (GCV) was introduced into HSVI-tk transfected ovarian cells. Through drawing the cell growth curve and flow cytometry, the killing effects of GCV on once and continuously GE7/HSVI-tk transfected cells were observed. Results: We found that the one time and continuous exogenous gene transfer efficiencies were about 80% and 85%, respectively. When 1 μg/mL GCV was used to treat ovarian cell transfected with HSVI-tk gene, growth inhibiting rates of ovarian cells of one time and continuous transferring were 82% and 90%, respectively; their apoptosis indices were 15 and 30, respectively. Under same GCV concentration, continuous mediation of GE7/pCMV-tk transfection into ovarian cancer cells had more significant inhibitory effect than one time mediation (P 〈 0.05). Conclusion: Compared with one time mediation, continuous mediation of transfection with GE7 gene delivery system has higher efficiency. Continuous mediation of GE7/HSVI-tk/GCV therapeutic gene system has more powerful killing effect.
文摘The installation of wind energy has increased rapidly around the world. The grid codes about the wind energy require wind turbine (WT) has the ability of fault (or low voltage) ride-through (FRT). To study the FRT operation of the wind farms, three methods were discussed. First, the rotor short current of doubly-fed induction generator (DFIG) was limited by introducing a rotor side protection circuit. Second, the voltage of DC bus was limited by a DC energy absorb circuit. Third, STATCOM was used to increase the low level voltages of the wind farm. Simulation under MATLAB was studied and the corresponding results were given and discussed. The methods proposed in this paper can limit the rotor short current and the DC voltage of the DFIG WT to some degree, but the voltage support to the power system during the fault largely depend on the installation place of STATCOM.
基金This study received was supported by the Natural Science Foundation of Fujian Province of China(2021J01621)Consultancy Project by the Chinese Academy of Engineering(2022-JB-06)Project for epidemiological characteristics analysis and clustering epidemics analysis of COVID-19 in Jinzhou City(JZ2024B066).
文摘The complex interactions were performed among non-pharmaceutical interventions,vaccinations,and hosts for all epidemics in China's Mainland during the spread of COVID-19.Specially,the small-scale epidemic in the city described by SVEIR model was less found in the current studies.The SVEIR model with control was established to analyze the dynamical and epidemiological features of two epidemics in Jinzhou City led by Omicron variants before and after Twenty Measures.In this study,the total population(N)of Jinzhou City was divided into five compartments:the susceptible(S),the vaccinated(V),the exposed(E),the infected(I),and the recovered(R).By surveillance data and the SVEIR model,three methods(maximum likelihood method,exponential growth rate method,next generation matrix method)were governed to estimate basic reproduction number,and the results showed that an increasing tendency of basic reproduction number from Omicron BA.5.2 to Omicron BA.2.12.1.Meanwhile,the effective reproduction number for two epidemics were investigated by surveillance data,and the results showed that Jinzhou wave 1 reached the peak on November 1 and was controlled 7 days later,and that Jinzhou wave 2 reached the peak on November 28 and was controlled 5 days later.Moreover,the impacts of non-pharmaceutical interventions(awareness delay,peak delay,control intensity)were discussed extensively,the variations of infection scales for Omicron variant and EG.5 variant were also discussed.Furthermore,the investigations on peaks and infection scales for two epidemics in dynamic zero-COVID policy were operated by the SVEIR model with control.The investigations on public medical requirements of Jinzhou City and Liaoning Province were analyzed by using SVEIR model without control,which provided a possible perspective on variant evolution in the future.
文摘采用包埋法制备了粒径均匀的海藻酸钙(CA)硝化菌小球,并用不同浓度的NaCl溶液处理CA硝化菌小球来改善其扩散传质性能,以N-异丙基丙烯酰胺(NIPAAm)、丙烯酸(AA)为单体材料,形成温度/pH响应层,制得一种新型温度/pH双响应硝化菌凝胶小球。以NH_(4)^(+)-N为指示物考察不同制备条件下硝化菌凝胶小球的氨氮去除性能及对温度、pH的敏感特性,并将其应用于实际废水的脱氮处理。结果表明,经浓度为0.3%的NaCl溶液改性后的CA硝化菌小球的扩散传质性能最佳;15 m L温度响应溶液中NIPAAm为200 mg、MBA为4 mg,10 mL pH响应溶液中AA为200 mg、MBA为4 mg时双响应硝化菌小球的氨氮去除性能最好;当温度低至4℃时,氨氮去除率可达29.45%,当pH为9时,氨氮去除率仍可达35.48%。双响应硝化菌凝胶小球具有良好的温度、pH敏感特性,对实际废水中氨氮的去除也具有良好效果,有利于提高低温及碱性条件下硝化菌的硝化效果。
基金supported by Natural Science Foundation of China to Chunzhi Zhang(32022075)the Agricultural Science and Technology Innovation Program(CAAS-ZDXT2018004)+5 种基金Shenzhen OutstandingTalent Training Fund to Sanwen Huang,Shenzhen Science and Technology Program(KQTD2016113010482651)Agricultural Science and Technology Innovation Program(CAASZDRW202101)Yunnan Fundamental Research Project(202001AV070003)the Natural Science Foundation of Shenzhen(JCYJ20190813142201666)supported by the Ministry of Agriculture and Rural Affairs of the People’s Republic of Chinathe Shenzhen municipal and Dapeng district governments。
文摘Heterosis is a fundamental biological phenomenon characterized by the superior performance of hybrids over their parents.Although tremendous progress has been reported in seed crops,the molecular mechanisms underlying heterosis in clonally propagated crops are largely unknown.Potato(Solanum tuberosum L.)is the most important tuber crop and an ongoing revolution is transforming potato from a clonally propagated tetraploid crop into a seed-propagated diploidhybrid potato.In our previous study,we developed the first generation of highly homozygous inbred lines of potato and hybrids with strong heterosis.Here,we integrated transcriptome,metabolome,and DNA methylation data to explore the genetic and molecular basis of potato heterosis at three developmental stages.We found that the initial establishment of heterosis in diploid potato was mainly due to dominant complementation.Flower color,male fertility,and starch and sucrose metabolism showed obvious gene dominant complementation in hybrids,and hybrids devoted more energy to primary metabolism for rapid growth.In addition,we identified~2700 allele-specific expression genes at each stage,which likely function in potato heterosis and might be regulated by CHH allele-specific methylation level.Our multi-omics analysis provides insight into heterosis in potato and facilitates the exploitation of heterosis in potato breeding.
基金supported by the National Basic Research Program of China(2012CB910902)the National Natural Science Foundation of China(9121730591017010)to H.G
文摘In plants, post-transcriptional gene silencing(PTGS) protects the genome from foreign genes and restricts the expression of certain endogenous genes for proper development. Here, we review the recent progress about how the unwanted PTGS is avoided in plants. As a decision-making step of PTGS, aberrant transcripts from most endogenous coding genes are strictly sorted to the bidirectional RNA decay pathways in cytoplasm but not to the short interference RNA(si RNA)-mediated PTGS, with the exception of a few development-relevant endogenous si RNA-producing genes. We also discuss a finely balanced PTGS threshold model that plants fully take advantage of the power of PTGS without self-harm.
基金supported by Special Projects of the Central Government Guiding Local Science and Technology Development (2021L3018)the Natural Science Foundation of Fujian Province of China (2021J01621)+2 种基金Consultancy Project by the Chinese Academy of Engineering (2022-JB-06)National Natural Science Foundation of China (12231012)Scientific Research Training Program in Fuzhou University (26040).
文摘Background:A COVID-19 outbreak in the rural areas of Shijiazhuang City was attributed to the complex interactions among vaccination,host,and non-pharmaceutical interventions(NPIs).Herein,we investigated the epidemiological characteristics of all reported symptomatic cases by picking Shijiazhuang City,Hebei Province in Northern China as research objective.In addition,we established an age-group mathematical model to perform the optimal fitting and to investigate the dynamical profiles under three scenarios.Methods:All reported symptomatic cases of Shijiazhuang epidemic(January 2-February 3,2021)were investigated in our study.The cases were classified by gender,age group and location,the distributions were analyzed by epidemiological characteristics.Furthermore,the reported data from Health Commission of Hebei Province was also analyzed by using an age-group mathematical model by two phases and three scenarios.Results:Shijiazhuang epidemic caused by SARS-CoV-2 wild strain was recorded with the peak 84 cases out of 868 reported symptomatic cases on January 11,2021,which was implemented with strong NPIs by local government and referred as baseline situation in this study.The research results showed that R0 under baseline situation ranged from 4.47 to 7.72,and Rt of Gaocheng Distinct took 3.72 with 95%confidence interval from 3.23 to 4.35 on January 9,the declining tendencies of Rt under baseline situation were kept till February 3,the value of Rt reached below 1 on January 19 and remained low value up to February 3 for Gaocheng District and Shijiazhuang City during Shijiazhuang epidemic.This indicated Shijiazhuang epidemic was under control on January 19.However,if the strong NPIs were kept,but remote isolation operated on January 11 was not implemented as of February 9,then the scale of Shijiazhuang epidemic reached 9,482 cases from age group who were 60 years old and over out of 31,017 symptomatic cases.The investigation also revealed that Shijiazhuang epidemic reached 132,648 symptomatic cases for age group who were 60 years old and over(short for G2)under risk-based strategies(Scenario A),58,048 symptomatic cases for G2 under late quarantine strategies(Scenario B)and 207,124 symptomatic cases for G2 under late quarantine double risk strategies(Scenario C),and that the corresponding transmission tendencies of Rt for three scenarios were consistently controlled on Jan 29,2021.Compared with baseline situation,the dates for controlling Rt below 1 under three scenarios were delayed 10 days.Conclusions:Shijiazhuang epidemic was the first COVID-19 outbreak in the rural areas in Hebei Province of Northern China.The targeted interventions adopted in early 2021 were effective to halt the transmission due to the implementation of a strict and village-wide closure.However we found that age group profile and NPIs played critical rules to successfully contain Shijiazhuang epidemic,which should be considered by public health policies in rural areas of China's Mainland during the dynamic zero-COVID policy.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 61571014) Beijing Natural Science Foundation (Grant No. 4164093).
文摘The intrusion events in the optical fiber pre-warning system (OFPS) are divided into two types which are harmful intrusion event and harmless interference event. At present, the signal feature extraction methods of these two types of events are usually designed from the view of the time domain. However, the differences of time-domain characteristics for different harmful intrusion events are not obvious, which cannot reflect the diversity of them in detail. We find that the spectrum distribution of different intrusion signals has obvious differences. For this reason, the intrusion signal is transformed into the frequency domain. In this paper, an energy ratio feature extraction method of harmful intrusion event is drawn on. Firstly, the intrusion signals are pre-processed and the power spectral density (PSD) is calculated. Then, the energy ratio of different frequency bands is calculated, and the corresponding feature vector of each type of intrusion event is further formed. The linear discriminant analysis (LDA) classifier is used to identify the harmful intrusion events in the paper. Experimental results show that the algorithm improves the recognition rate of the intrusion signal, and further verifies the feasibility and validity of the algorithm.
基金This study was supported by grants from the Consultancy Project by the Chinese Academy of Engineering(CAE,2022-JB-06)the Natural Science Foundation of Fujian Province(2021 J01621)+1 种基金the National Natural Science Foundation of China(No.61873154)the National Key R&D Program of China(2021ZD0114102).
文摘The World Health Organization(WHO)declared monkeypox as a public health emergency of international concern(PHEIC)on July 23,2022,their highest level of alert.This raised concerns about the management of the global monkeypox outbreak,as well as the scientific analysis and accurate prediction of the future course of the epidemic.This study used EpiSIX(an analysis and prediction system for epidemics based on a general SEIR model)to analyze the monkeypox epidemic and to forecast the major tendencies based on data from the USA CDC(https://www.cdc.gov)and the WHO(https://www.who.int/health-topics/monkeypox).The global outbreak of monkeypox started in the UK on May 2,2022,which marked the beginning of an epidemic wave.As of October 28,2022,the cumulative number of reported cases worldwide was 77,115,with 36 deaths.EpiSIX simulations predict that the global monkeypox epidemic will enter a low epidemic status on March 1,2023 with the cumulative number of confirmed cases ranging from 85,000 to 124,000,and the total number of deaths ranging from 60 to 87.Our analysis revealed that the basic reproduction number(R0)of monkeypox virus(MPXV)is near to 3.1 and the percentage of asymptomatic individuals is 13.1%–14.5%,both of which are similar to the data for SARS.The vaccination efficiency against susceptibility(VEs)of individuals who have had monkeypox is~79%,and the vaccination efficiency against infectiousness(VEi)of individuals who have had monkeypox is~76%–82%.The mean incubation period for monkeypox is 8 days.In total,94.7%of infected individuals develop symptoms within 20 days and recover within 2 weeks after the confirmation of symptoms.Simulation results using EpiSIX showed that ring vaccination was remarkably effective against monkeypox.Our findings confirmed that a 20-day isolation for close contacts is necessary.
基金Acknowledgements This work was supported by the National Natural Science Foundation of China (Grant No. 50838005) and National Water Pollution Control and Management Technology Major Projects of China (No. 2009ZX07317-009). The authors are grateful for much assistance with microsensor measurements from Xi'an University Architecture and Technol- ogy.
文摘This paper reports the effects of shear force on anoxic granular sludge in sequencing batch reactors (SBR). The study was carried out in two SBRs (SBR1 and SBR2) in which sodium acetate (200mg COD·L^-1) was used as the sole substrate and sodium nitrate (40 mgNO3-N·L^-1) was employed as the electron acceptor. The preliminary objective of this study was to cultivate anoxic granules in the SBR in order to investigate the effects of shear force on the formation of anoxic granular sludge and to compare the properties of anoxic sludge in the SBR. This study reports new results for the values of average velocity gradient, a measure of the applied shear force, which was varied in the two SBRs (3.79 s^-1 and 9.76 s^-1 for SBR1 and SBR2 respectively). The important findings of this research highlight the dual effects of shear force on anoxic granules. A low shear force can produce large anoxic granules with high activity and poor settling ability, whereas higher shear forces produce smaller granules with better settling ability and lower activity. The results of this study show that the anoxic granulation is closely related to the strength of the shear force. For high shear force, this research demonstrated that: 1) granules with smaller diameters, high density and good settling ability were formed in the reactor, and 2) granular sludge formed faster than it did in the low shear force reactor (41days versus 76 days). Once a steady-state has been achieved, the nitrate and COD removal rates were found to be 98% and 80%, respectively. For low shear force, such as was applied in SBR1, this research demonstrated that: 1) the activity of anoxic granular sludge in low shear force was higher than that in high shear force, 2) higher amount of soluble microbial products (SMPs) were produced, and 3) large pores were observed inside the larger granules,which are beneficial for nitrogen gas diffusion. Electron microscopic examination of the anoxic granules in both reactors showed that the morphology of the granules was ellipsoidal with a clear outline. Coccus and rod-shaped bacteria were wrapped by filamentous bacteria on the surface of granule.
文摘Anoxic granular sludge was developed in a laboratory-scale sequencing batch reactor which was fed with sodium acetate and sodium nitrate as electron donor and accepter. The sludge in the reactor was almost granulated after approximately 90 days of cultivation. In the present study, a detailed examination of surface morphology and internal structure of anoxic granular sludge was conducted using scanning electron microscope. It showed that the bacteria inside the granules had a uniform, coccus-like shape. By contrast, filamentous bacteria were predominant outside the granules. These bacteria were woven and had wrapped the coccus bacteria together to form granules. The small amounts of DO in the liquid bulk promoted the growth of filamentous bacteria on the surface of the granules. A string-bag hypothesis was proposed to elucidate the structure and formation of the anoxic granular sludge. It suggested that micro-aeration could be a method to promote granulation in practical anoxic treatment systems.
文摘This paper investigates the relationship between intra-regional accessibility and economic development within the Cardiff City Region. Embracing the Capital City of Cardiff and its hinterland, this region is regarded as the economically most important one in Wales, and the key driver of Wale's current and future economic prosperity. Therefore, it is a significant problem how to fully realize its economic potential and its national role, and it is also controversial whether poor intra-regional accessibility is the biggest barrier to its further growth. This has been debated for years and provoked great research interest. By using a qualitative methodology, the paper identifi es that intra-regional accessibility is necessary, though not suff icient, for economic growth. It is necessary since it can increase the productivity of economic activities and infl uence the fi rms' location behavior, based on which this paper proposes some recommendations for economic development.
基金This study was supported by grants from a Consultancy Project of the Chinese Academy of Engineering(CAE,2022-JB-06)Natural Science Foundation of Shaanxi Province,China(2023-JC-YB-676)+1 种基金Innovation Foundation of Medical Research Project of Xi’an City(2022YXYJ0040)Natural Science Foundation of Fujian Province of China(2021 J01621).
文摘The prediction system EpiSIX was used to study the COVID-19 epidemic in China's Mainland between November 2022 and January 2023,based on reported data from December 9,2022,to January 30,2023,released by The Chinese Center for Disease Control and Prevention on February 1,2023.Three kinds of reported data were used for model fitting:the daily numbers of positive nucleic acid tests and deaths,and the daily number of hospital beds taken by COVID-19 patients.It was estimated that the overall infection rate was 87.54%and the overall case fatality rate was 0.078%–0.116%(median 0.100%).Assuming that a new COVID-19 epidemic outbreak would start in March or April of 2023,induced by a slightly more infectious mutant strain,we predicted a possible large rebound between September and October 2023,with a peak demand of between 800,000 and 900,000 inpatient beds.If no such new outbreak was induced by other variants,then the current COVID-19 epidemic course in China's Mainland would remain under control until the end of 2023.However,it is suggested that the necessary medical resources be prepared to manage possible COVID-19 epidemic emergencies in the near future,especially for the period between September and October 2023.