[Objective] The aim was to improve part of auto-control system of aquatic seedling breeding and to lay foundation for highly-efficient and stable use of the sys- tem. [Method] The executive and drive modules of the au...[Objective] The aim was to improve part of auto-control system of aquatic seedling breeding and to lay foundation for highly-efficient and stable use of the sys- tem. [Method] The executive and drive modules of the auto-control system were im- proved, after which real-time monitor, data display and alarm modules were tested on time. [Result] In the test, for the improved system, stability and sensitivity were enhanced; different components matched better; transmitting electric resistanc6 was reduced. [Conclusion] The research provides references for auto-control of water temperature and dissolved oxygen, and faults clearing in aquatic seedling breeding.展开更多
Studies were initiated for two consecutive years to find out the effect of time of transplanting and seedlings hill^-l on the productivity of rice in Dera Ismail Khan district of North West Frontier Province （NWFP）,...Studies were initiated for two consecutive years to find out the effect of time of transplanting and seedlings hill^-l on the productivity of rice in Dera Ismail Khan district of North West Frontier Province （NWFP）, Pakistan. The experiment was laid out in a randomized complete block design with split plot arrangements. Main plots consisted of four transplanting dates viz. 20th and 27th of June and 4th and 1 lth of July while sub-plots contained 1, 2, 3 or 4 seedlings hill^-1. Among transplanting dates, June 20th planted crop gave highest paddy yield and net return with I seedling hill^-1. It explains that the use of more seedlings hill^-1 not only adds to cost but is also a mere wastage of natural resources. Based on research findings, we conclude that the use of I seedling hill^-1 is most appropriate for timely sowing otherwise 4 seedlings hill^-1 should be used to compensate for the yield gap in late transplanted rice.展开更多
The habanero chili （Capsicum chinense Jacq.） is a species of great demand in the domestic and international markets. One problem in the cultivation is low percentage of seed germination. There is little information ...The habanero chili （Capsicum chinense Jacq.） is a species of great demand in the domestic and international markets. One problem in the cultivation is low percentage of seed germination. There is little information on the use of promoters and imbibition time to increase this parameter, without compromising the quality of seedlings. In this context, authors assessed the independent effect of GAs （gibberellic acid） and KNOs at concentrations of 0, 100, 200, 300, 400 and 500 mg·L1. Seeds without preconditioning were the witness. The experimental unit was a Petri dish with 50 seeds on filter paper placed equidistant. There were three replicates per treatment and the experimental design was randomized complete block. Imbibition time was 24 h. The experimental units were kept in an incubator at 22 ± 2 ℃. From the time of planting and for periods of 24 h for 14 d, experimental units were reviewed to determine the time at the beginning of germination and the total cumulative percentage. The authors also determined the number of normal and abnormal seedlings, the length of hypocotyl and radicle, weight of fresh and dry matter of seedlings. On the fifth day after sowing in vitro, concentrations of 500 mg·L^-1 of GAs, 300 and 400 mg·L^-1 KNO3, increased 208% the percentage of seed germination of habanero chile. On day 14 after sowing in vitro concentrations of 500 mg·L^-1 GA3, 300 and 400 mg·L^-1 KNO3, increased 23% normal seedlings and 40% dry matter thereof, with respect to seeds obtained without preconditioning. Unconditioned seeds before sowing produced 125% more seedlings.展开更多
Artificial seedling production of Sargassum thunbergii is an effective way to relieve pressure on natural resources.In order to improve the utilization of zygotes and reduce the loss of seedlings,studies on the charac...Artificial seedling production of Sargassum thunbergii is an effective way to relieve pressure on natural resources.In order to improve the utilization of zygotes and reduce the loss of seedlings,studies on the characteristic of the zygotes release,the development of rhizoids,the attachment of germlings,and the influence of jet washing were conducted.Results show that the percent of zygotes released was increased with time in the first 60 h.The capacity of germlings attached to the substratum was significantly increased,especially coincident with the time of the new rhizoids emerged and elongated.The detachment rate of germlings significantly decreased with the delay of starting time of jet washing or the reduction of jet washing velocity.However,the jet washing at any level applied in the experiment could cause considerable loss of germlings within the 20 days after the attachment.Our study provided some parameters to optimize the operation in the early stage of seedling production.展开更多
The use of cholera vaccines has been increasingly recognized as an effective control measure in cholera endemic countries. However, guidelines for using vaccination during cholera outbreaks are still to be established...The use of cholera vaccines has been increasingly recognized as an effective control measure in cholera endemic countries. However, guidelines for using vaccination during cholera outbreaks are still to be established, and it remains an open question as to how and when the vaccines should be deployed to best control ongoing cholera outbreaks. Here we formulate a new optimal control model to assess the value of cholera vaccines in epidemic settings and cost-effective optimal times to deploy a vaccine. Our results suggest that as long as the vaccine prices are sufficiently low, vaccination should always start from or immediately after the onset of a cholera outbreak.展开更多
In this paper, an SIRS epidemic model with time delay and vaccination is investigated. By analyzing the corresponding characteristic equation, the local stability of diseasefree equilibrium of the model is established...In this paper, an SIRS epidemic model with time delay and vaccination is investigated. By analyzing the corresponding characteristic equation, the local stability of diseasefree equilibrium of the model is established. By constructing Lyapunov functional, sufficient conditions are established for the local stability of an endemic equilibrium of the model. Further, a threshold value is obtained. By using comparison arguments, it is proved when the threshold value is less than unity, the diseasefree equilibrium is globally asymptoti cally stable. When the threshold value is greater than unity, by using an iteration scheme and by constructing appropriate Lyapunov functional, respectively, sufficient conditions are derived for the global stability of the endemic equilibrium of the model. Numerical simulations are carried out to illustrate the theoretical results.展开更多
Influenza H1N1 has been found to exhibit oscillatory levels of incidence in large pop- ulations. Clear peaks for influenza H1N1 are observed in several countries including Vietnam each year [M. F. Boni, B. H. Manh, P....Influenza H1N1 has been found to exhibit oscillatory levels of incidence in large pop- ulations. Clear peaks for influenza H1N1 are observed in several countries including Vietnam each year [M. F. Boni, B. H. Manh, P. Q. Thai, J. Farrar, T. Hien, N. T. Hien, N. Van Kinh and P. Horby, Modelling the progression of pandemic influenza A （H1N1） in Vietnam and the opportunities for reassortment with other influenza viruses, BMC Med. 7 （2009） 43, Doi： 10.1186/1741-7015-%43]. So it is important to study seasonal forces and factors which can affect the transmission of this disease. This paper studies an SIRS epidemic model with seasonal vaccination rate. This SIRS model has a unique disease-free solution （DFS）. The value Ro, the basic reproduction number is obtained when the vaccination is a periodic function. Stability results for the DFS are obtained when R0 〈 1. The disease persists in the population and remains endemic if R0 〉 1. Also when R0 〉 1 existence of a nonzero periodic solution is proved. These results obtained for our model when the vaccination strategy is a non-constant time-dependent function.展开更多
In this paper, based on a class of multi-group epidemic models of SEIR type with bilinear incidences, we introduce a vaccination compartment, leading to multi-group SVEIR model. We establish that the global dynamics a...In this paper, based on a class of multi-group epidemic models of SEIR type with bilinear incidences, we introduce a vaccination compartment, leading to multi-group SVEIR model. We establish that the global dynamics are completely determined by the basic reproduction number R0V which is defined by the spectral radius of the next generation matrix. Our proofs of global stability of the equilibria utilize a graph-theoretical approach to the method of Lyapunov functionals. Mathematical results suggest that vaccination is helpful for disease control by decreasing the basic reproduction number. However, there is a necessary condition for successful elimination of disease. If the time for the vaccines to obtain immunity or the possibility for them to be infected before acquiring immunity is neglected in each group, this condition will be satisfied and the disease can always be eradicated by suitable vaccination strategies. This may lead to over evaluation for the effect of vaccination.展开更多
文摘[Objective] The aim was to improve part of auto-control system of aquatic seedling breeding and to lay foundation for highly-efficient and stable use of the sys- tem. [Method] The executive and drive modules of the auto-control system were im- proved, after which real-time monitor, data display and alarm modules were tested on time. [Result] In the test, for the improved system, stability and sensitivity were enhanced; different components matched better; transmitting electric resistanc6 was reduced. [Conclusion] The research provides references for auto-control of water temperature and dissolved oxygen, and faults clearing in aquatic seedling breeding.
文摘Studies were initiated for two consecutive years to find out the effect of time of transplanting and seedlings hill^-l on the productivity of rice in Dera Ismail Khan district of North West Frontier Province （NWFP）, Pakistan. The experiment was laid out in a randomized complete block design with split plot arrangements. Main plots consisted of four transplanting dates viz. 20th and 27th of June and 4th and 1 lth of July while sub-plots contained 1, 2, 3 or 4 seedlings hill^-1. Among transplanting dates, June 20th planted crop gave highest paddy yield and net return with I seedling hill^-1. It explains that the use of more seedlings hill^-1 not only adds to cost but is also a mere wastage of natural resources. Based on research findings, we conclude that the use of I seedling hill^-1 is most appropriate for timely sowing otherwise 4 seedlings hill^-1 should be used to compensate for the yield gap in late transplanted rice.
文摘The habanero chili （Capsicum chinense Jacq.） is a species of great demand in the domestic and international markets. One problem in the cultivation is low percentage of seed germination. There is little information on the use of promoters and imbibition time to increase this parameter, without compromising the quality of seedlings. In this context, authors assessed the independent effect of GAs （gibberellic acid） and KNOs at concentrations of 0, 100, 200, 300, 400 and 500 mg·L1. Seeds without preconditioning were the witness. The experimental unit was a Petri dish with 50 seeds on filter paper placed equidistant. There were three replicates per treatment and the experimental design was randomized complete block. Imbibition time was 24 h. The experimental units were kept in an incubator at 22 ± 2 ℃. From the time of planting and for periods of 24 h for 14 d, experimental units were reviewed to determine the time at the beginning of germination and the total cumulative percentage. The authors also determined the number of normal and abnormal seedlings, the length of hypocotyl and radicle, weight of fresh and dry matter of seedlings. On the fifth day after sowing in vitro, concentrations of 500 mg·L^-1 of GAs, 300 and 400 mg·L^-1 KNO3, increased 208% the percentage of seed germination of habanero chile. On day 14 after sowing in vitro concentrations of 500 mg·L^-1 GA3, 300 and 400 mg·L^-1 KNO3, increased 23% normal seedlings and 40% dry matter thereof, with respect to seeds obtained without preconditioning. Unconditioned seeds before sowing produced 125% more seedlings.
基金Supported by the Public Science and Technology Research Funds Projects of Ocean(Nos.201305021,201305043,201305005,201405040)the National Natural Science Foundation of China(No.41376129)the Scientific Funds for Outstanding Young Scientists of Shandong Province Award(No.BS2012HZ013)
文摘Artificial seedling production of Sargassum thunbergii is an effective way to relieve pressure on natural resources.In order to improve the utilization of zygotes and reduce the loss of seedlings,studies on the characteristic of the zygotes release,the development of rhizoids,the attachment of germlings,and the influence of jet washing were conducted.Results show that the percent of zygotes released was increased with time in the first 60 h.The capacity of germlings attached to the substratum was significantly increased,especially coincident with the time of the new rhizoids emerged and elongated.The detachment rate of germlings significantly decreased with the delay of starting time of jet washing or the reduction of jet washing velocity.However,the jet washing at any level applied in the experiment could cause considerable loss of germlings within the 20 days after the attachment.Our study provided some parameters to optimize the operation in the early stage of seedling production.
基金J. Wang acknowledges partial support from the National Science Foundation under Grant Nos. 0813691 and 1216936. Z. Mukandavire was supported by the UF Science for Life Program, an interdisciplinary program with support from the Howard Hughes Medical Institute. The authors would like to thank the anonymous referees for helpful comments.
文摘The use of cholera vaccines has been increasingly recognized as an effective control measure in cholera endemic countries. However, guidelines for using vaccination during cholera outbreaks are still to be established, and it remains an open question as to how and when the vaccines should be deployed to best control ongoing cholera outbreaks. Here we formulate a new optimal control model to assess the value of cholera vaccines in epidemic settings and cost-effective optimal times to deploy a vaccine. Our results suggest that as long as the vaccine prices are sufficiently low, vaccination should always start from or immediately after the onset of a cholera outbreak.
文摘In this paper, an SIRS epidemic model with time delay and vaccination is investigated. By analyzing the corresponding characteristic equation, the local stability of diseasefree equilibrium of the model is established. By constructing Lyapunov functional, sufficient conditions are established for the local stability of an endemic equilibrium of the model. Further, a threshold value is obtained. By using comparison arguments, it is proved when the threshold value is less than unity, the diseasefree equilibrium is globally asymptoti cally stable. When the threshold value is greater than unity, by using an iteration scheme and by constructing appropriate Lyapunov functional, respectively, sufficient conditions are derived for the global stability of the endemic equilibrium of the model. Numerical simulations are carried out to illustrate the theoretical results.
文摘Influenza H1N1 has been found to exhibit oscillatory levels of incidence in large pop- ulations. Clear peaks for influenza H1N1 are observed in several countries including Vietnam each year [M. F. Boni, B. H. Manh, P. Q. Thai, J. Farrar, T. Hien, N. T. Hien, N. Van Kinh and P. Horby, Modelling the progression of pandemic influenza A （H1N1） in Vietnam and the opportunities for reassortment with other influenza viruses, BMC Med. 7 （2009） 43, Doi： 10.1186/1741-7015-%43]. So it is important to study seasonal forces and factors which can affect the transmission of this disease. This paper studies an SIRS epidemic model with seasonal vaccination rate. This SIRS model has a unique disease-free solution （DFS）. The value Ro, the basic reproduction number is obtained when the vaccination is a periodic function. Stability results for the DFS are obtained when R0 〈 1. The disease persists in the population and remains endemic if R0 〉 1. Also when R0 〉 1 existence of a nonzero periodic solution is proved. These results obtained for our model when the vaccination strategy is a non-constant time-dependent function.
文摘In this paper, based on a class of multi-group epidemic models of SEIR type with bilinear incidences, we introduce a vaccination compartment, leading to multi-group SVEIR model. We establish that the global dynamics are completely determined by the basic reproduction number R0V which is defined by the spectral radius of the next generation matrix. Our proofs of global stability of the equilibria utilize a graph-theoretical approach to the method of Lyapunov functionals. Mathematical results suggest that vaccination is helpful for disease control by decreasing the basic reproduction number. However, there is a necessary condition for successful elimination of disease. If the time for the vaccines to obtain immunity or the possibility for them to be infected before acquiring immunity is neglected in each group, this condition will be satisfied and the disease can always be eradicated by suitable vaccination strategies. This may lead to over evaluation for the effect of vaccination.
