An optimization model and its solution algorithm for alternate traffic restriction(ATR) schemes were introduced in terms of both the restriction districts and the proportion of restricted automobiles. A bi-level progr...An optimization model and its solution algorithm for alternate traffic restriction(ATR) schemes were introduced in terms of both the restriction districts and the proportion of restricted automobiles. A bi-level programming model was proposed to model the ATR scheme optimization problem by aiming at consumer surplus maximization and overload flow minimization at the upper-level model. At the lower-level model, elastic demand, mode choice and multi-class user equilibrium assignment were synthetically optimized. A genetic algorithm involving prolonging codes was constructed, demonstrating high computing efficiency in that it dynamically includes newly-appearing overload links in the codes so as to reduce the subsequent searching range. Moreover,practical processing approaches were suggested, which may improve the operability of the model-based solutions.展开更多
Background The aggravating trend of aging population has brought us with great medical challenges. Calorie restriction （CR） has various beneficial effects on health, including lifespan prolongation and functional im...Background The aggravating trend of aging population has brought us with great medical challenges. Calorie restriction （CR） has various beneficial effects on health, including lifespan prolongation and functional im- provement of multiple organisms. SIRT6, a member of the Sirtuin family of NAD^＋-dependent histone deacetylases, has been shown to play a key role in mediating the effects of CR. Aim Here we show how CR-triggered SIRT6-de- pendent pathways affect aging and the critical role of SIRT6 on inflammation. Methods 24-month-old mice were fed under ad libitum （AL） or CR condition for 6 months to determine the effects of CR. In addition, we took low glucose （LG） cultured WI38 human fibroblasts as a model to mimic CR in vitro. Further more, we stably overex- pressed or knockdown SIRT6 in WI38 to identify the role of SIRT6 in cell senescence and inflammation. Results Aged mice with CR had improved renal pathology and enhanced SIRT6 expression compared with AL group. In ad- dition, compared with normal glucose （NG） group, LG group had prolonged lifespan and increased expression of SIRT6. Furthermore, increased SA-β-gal positive cells were observed in SIRT6-deficient cells while the overexpres- sion of SIRT6 could delay the replicative senescence effectively. NF-KB was involved in the SIRT6 mediated lon- gevity control. SIRT6 overexpressed WI38 had low translocate rate of NF-KB into the nucleus and SIRT6 could at- tenuate the NF-KB signaling by deacetylating the RelA subunit of NF-KB complex. Conclusion In this study, we show that CR prevents age-dependent renal insufficiency by up-regulation of SIRT6. CR-triggered SIRT6 activation suppresses NF-KB signaling via preventing nuclear translocation of NF-KB. Here we identified the beneficial effects of CR on renal aging and determined the crucial role of SIRT6 on CR-mediated lifespan extension.展开更多
Restriction enzyme digestion of total genomic DNA of two chro-mosome type Paragonimus westermani showed the presence of homologus highlyrepeated DNA in diploid and triploid forms. Southern blot analysis providedfurthe...Restriction enzyme digestion of total genomic DNA of two chro-mosome type Paragonimus westermani showed the presence of homologus highlyrepeated DNA in diploid and triploid forms. Southern blot analysis providedfurther evidence that the distribution of restriction enzyme sites (with 3enzymes) on repeated DNA of both was similar. But with Pst Ⅰ、Dde Ⅰ、Hae Ⅲand Hpa Ⅱ. They revealed polymorphism which also occured individually ineach form tested separatedly with hybridization technique. Mutation of recog-nize sites by enzymes, which is resulted from the alternation of gene sequance,has occured during evolution. Additionally, it is probably possible, based on PstⅠand Dde Ⅰdigest pattern to distinguish between diploid and triploid Parag-onimus westermani and group the Paragonimus simply and rapidly.展开更多
The study was carried out to investigate the effects of maternal dietary energy restriction on growth performance, serum indices and fat deposition of offspring. A total of 400 female Arbor Acres （AA） broiler breede...The study was carried out to investigate the effects of maternal dietary energy restriction on growth performance, serum indices and fat deposition of offspring. A total of 400 female Arbor Acres （AA） broiler breeders were studied. These female birds involved three experimental treatments and a control group with normal dietary energy diets （ND, 11.7 MJ of ME. kgt during the laying）. In treatments 2, 3 and 4, the energies of diets were 20%, 30% and 50% （LD20, LD30 and LD50） lower than those of the control, respectively. The study commenced at the beginning of the laying period when the total egg production reached 5% of the flock. All the broiler offspring were fed the same diets. The results showed that in low energy diets, offspring showed decreased 1-day-old weight, but 49-day-old weight was higher in LD20 diet （P〈0.05）. For offspring during days 1-49, the average daily gain （ADG） in LD20 group and the feed conversion ratio in LD50 group were improved as compared with those of the control （P〈0.05）. Compared with the control, abdominal fat percentage increased in 49-day-old offspring from LD30 diet （P〈0.05）; the fat content of breast muscle in offspring increased in broilers fed low energy diets （P〈0.05）. In 28-day-old offspring from breeders given LD20 and LD50 diets, liver fat percentages were higher compared with ND （P〈0.05）. The subcutaneous fat thickness in 28-day-old offspring from LD50 group and 49-day-old offspring from LD30 group was higher （P〈0.05）. On day 49, the serum cholesterol （CHO） of offspring from breeders fed LD20 diet and serum high-density lipoprotein （HDL） of offspring from breeders fed LD50 diet reduced compared with those of the control （P〈0.05）. In addition, a higher triiodothyronine （T3） content in serum was found in offspring from broiler breeders given LD20 and LD30 diets （P〈0.05）. Serum thyroxine （T4） in offspring significantly decreased with the decrease of diet energy （P〈0.05）. In conclusion, to a certain extent, dietary energy restriction in breeders could improve growth performance and promote lipid metabolism of offspring.展开更多
An experiment was conducted to study the influence of eady quantitative feed restriction on the performance and carcass characteristics of broiler chickens. Two hundred 8-day-old commercial Avian male broiler chicks w...An experiment was conducted to study the influence of eady quantitative feed restriction on the performance and carcass characteristics of broiler chickens. Two hundred 8-day-old commercial Avian male broiler chicks were assigned to four groups randomly, with 50 broilers each. At the age of 8 days the broilers were restricted to 90%, 80% or 70% of the ad libitum intake for 7 days. When the restricion was finished, all birds received feed ad libitum again. The results showed that diet restriction resulted in a reduction in body weight and daily gain during the restriction period （P 〈0.05）. The birds restricted to 90% of the ad libitum intake showed the occurring of growth compensation in the 3rd week. The birds restricted to 80% and 70% of the ad libitum intake had growth compensation in the 4th week. No significant differences between the effects of the restriction and the control on final body weight, growth rate, feed conversion efficiency and carcass characteristics （P 〈0.05）.展开更多
The patterns of cleavage of mtDNA by restriction endonucleases was analysed for six fowl breeds and of. Hyline White, Hyline Brown, ISA Brown, Hisex Brown, Lohmann White, Abor Acres and mtDNA polymorphisms were detect...The patterns of cleavage of mtDNA by restriction endonucleases was analysed for six fowl breeds and of. Hyline White, Hyline Brown, ISA Brown, Hisex Brown, Lohmann White, Abor Acres and mtDNA polymorphisms were detected in the restriction patterns with the following eight enzymes, Ava Ⅰ, Ava Ⅱ, EcoR Ⅰ, Hind Ⅲ, Bam HI, Pvu Ⅱ, Pst Ⅰ, Hinc Ⅱ. The restriction cleavage patterns were identical among these breeds. Hyline White, Hyline Brown, ISA Brown, Hisex Brown, Lohmann White—A type. The patterns of Abor Acres were B type. Based on their mtDNA restriction types, all the breeds were classified into two groups. Genetic distances among these groups were calculated in order to define their phylogenetic relationships. The relationship among five egg line breeds is close, while Abor Acres (Broiler fowl) is relatively far from them. The results suggest that the difference of mtDNA could result from the different origins. The polymorphic sites in mtDNA of Hyline White has been located on a restriction map.展开更多
Improvement of integrated battlefield situational awareness in complex environments involving dynamic factors such as restricted communications and electromagnetic interference(EMI)has become a contentious research pr...Improvement of integrated battlefield situational awareness in complex environments involving dynamic factors such as restricted communications and electromagnetic interference(EMI)has become a contentious research problem.In certain mission environments,due to the impact of many interference sources on real-time communication or mission requirements such as the need to implement communication regulations,the mission stages are represented as a dynamic combination of several communication-available and communication-unavailable stages.Furthermore,the data interaction between unmanned aerial vehicles(UAVs)can only be performed in specific communication-available stages.Traditional cooperative search algorithms cannot handle such situations well.To solve this problem,this study constructed a distributed model predictive control(DMPC)architecture for a collaborative control of UAVs and used the Voronoi diagram generation method to re-plan the search areas of all UAVs in real time to avoid repetition of search areas and UAV collisions while improving the search efficiency and safety factor.An attention mechanism ant-colony optimization(AACO)algorithm is proposed for UAV search-control decision planning.The search strategy is adaptively updated by introducing an attention mechanism for regular instruction information,a priori information,and emergent information of the mission to satisfy different search expectations to the maximum extent.Simulation results show that the proposed algorithm achieves better search performance than traditional algorithms in restricted communication constraint scenarios.展开更多
A novel coronavirus, severe acute respiratory syndrome (SA RS)-associated coronavirus (SARS-CoV), has been identified as the causal agent of SARS. Spike (S) protein is a major structural glycoprotein of the SARS virus...A novel coronavirus, severe acute respiratory syndrome (SA RS)-associated coronavirus (SARS-CoV), has been identified as the causal agent of SARS. Spike (S) protein is a major structural glycoprotein of the SARS virus and a potential target for SARS-specific cell-mediated immune responses. A pa nel of S protein-derived peptides was tested for their binding affinity to HLA -A *0201 molecules. Peptides with high affinity for HLA-A *0201 were then as se ssed for their capacity to elicit specific immune responses mediated by cytotoxi c T lymphocytes (CTLs) both in vivo, in HLA-A2.1/K b transgenic mice, a nd in vitro, from peripheral blood lymphocytes (PBLs) harvested from healthy HLA-A 2.1 + donors. SARS-CoV protein-derived peptide-1 (SSp-1 RLNEVAKNL), induced pepti de-specific CTLs both in vivo (transgenic mice) and in vitro (human PBL s), which specifically released interferon-gamma (IFN-gamma) upon stimulation with SSp-1-pulsed autologous dendritic cells (DCs) or T2 cells. SSp-1-specif ic CTLs also lysed major histocompatibility complex (MHC)-matched tumor cell lines engineered to express S proteins. HLA-A *0201-SSp-1 tetramer staining re vealed the presence of significant populations of SSp-1-specific CTLs in SSp- 1-induced CD8 + T cells. We propose that the newly identified epitope SSp-1 w ill help in the characterization of virus control mechanisms and immunopathology in SARS-CoV infection, and may be relevant to the development of immunotherape utic approaches for SARS.展开更多
A wide variety of human tumors express interleukin10 (IL-10) for reasons poorly understood. We haveanalysed the effect of spontaneous IL-10 expression by amouse tumor (J558L) on its immunparalysing effect.Because cros...A wide variety of human tumors express interleukin10 (IL-10) for reasons poorly understood. We haveanalysed the effect of spontaneous IL-10 expression by amouse tumor (J558L) on its immunparalysing effect.Because cross-priming" of T cells by host antigenpresenting cells for MHC class I restricted tumor antigensis a major pathway for induction of tumor immunity andthat is enhanced by granulocyte-macrophage colony-stimulating factor (GM-CSF), we expressed this cytokinein J558L cells. GM-CSF secreting cells were not展开更多
Compared with the conventionally gaseous or liquid working media,the specific internal energy of supercritical carbon dioxide(SCD)is higher at the same temperature and pressure,and the critical temperature of carbon d...Compared with the conventionally gaseous or liquid working media,the specific internal energy of supercritical carbon dioxide(SCD)is higher at the same temperature and pressure,and the critical temperature of carbon dioxide is close to room temperature,making SCD a potential new working medium for pneumatic launch.To analyze the feasibility of this conception,an analytical model of a pneumatic catapult is established on basis of the conservations of mass and energy.The model consists of a high-pressure chamber and a low-pressure chamber connected by multiple valves,and there is a movable piston in the low-pressure chamber that can push an aircraft to accelerate.The effects of the launch readiness state of SCD in the high-pressure chamber,the initial volume of the low-pressure chamber and the valve control on the movement of the aircraft are analyzed.It is found that there is a restrictive relation between the temperature and pressure of the launch readiness state of SCD,i.e.,there is a maximum allowable launch readiness pressure when the launch readiness temperature is fixed.If this restrictive relation is not satisfied,the working medium in the low-pressure chamber will drop to its triple point within a few milliseconds,leading to a launch failure.Owing to this restrictive relation,there is an optimal launch readiness state of SCD with the highest working capacity for any allowable launch readiness temperature.The pressure of the low-pressure chamber will decrease significantly as the initial volume increases,leading to a decreased acceleration of the aircraft.The acceleration can be controlled below a critical value by a designed sequential blasting technique of multiple valves.The calculated results show that a 500 kg aircraft can be accelerated from 0 to 58 m/s in 0.9 s with 36 kg of carbon dioxide.This research provides a new technique for the controllable cold launch of an aircraft.展开更多
Solving the financing problem in rural areas and improving the level of economic development in rural areas become important guarantees for the expansion of domestic demand. This research, through studying the current...Solving the financing problem in rural areas and improving the level of economic development in rural areas become important guarantees for the expansion of domestic demand. This research, through studying the current situation of rural financing, pointed out the main factors restricting the financing in rural areas, such as high risk credit, slow income growth, high financing cost and difficult mortgage and guaranteed loans. Based on those, the author worked out the objectives and direction of China＇s rural financing reform, from two aspects of path selection of reform and innovation and specific embodiments for adjusting the overall reconstruction, and put forward some relevant countermeasures.展开更多
This review article aims to give a comprehensive review of periodic orbits in the circular restricted three-body problem(CRTBP),which is a standard ideal model for the Earth-Moon system and is closest to the practical...This review article aims to give a comprehensive review of periodic orbits in the circular restricted three-body problem(CRTBP),which is a standard ideal model for the Earth-Moon system and is closest to the practical mechanical model.It focuses the attention on periodic orbits in the Earth-Moon system.This work is primarily motivated by a series of missions and plans that take advantages of the three-body periodic orbits near the libration points or around two gravitational celestial bodies.Firstly,simple periodic orbits and their classification that is usually considered to be early work before 1970 are summarized,and periodic orbits around Lagrange points,either planar or three-dimensional,are intensively studied during past decades.Subsequently,stability index of a periodic orbit and bifurcation analysis are presented,which demonstrate a guideline to find more periodic orbits inspired by bifurcation signals.Then,the practical techniques for computing a wide range of periodic orbits and associated quasi-periodic orbits,as well as constructing database of periodic orbits by numerical searching techniques are also presented.For those unstable periodic orbits,the station keeping maneuvers are reviewed.Finally,the applications of periodic orbits are presented,including those in practical missions,under consideration,and still in conceptual design stage.This review article has the function of bridging between engineers and researchers,so as to make it more convenient and faster for engineers to understand the complex restricted three-body problem(RTBP).At the same time,it can also provide some technical thinking for general researchers.展开更多
The roundabouts are widely used in China,some of which have central islands as scenic spots.The crosswalks connecting to the central islands,normally full of pedestrians,have negative impact on roundabout capability a...The roundabouts are widely used in China,some of which have central islands as scenic spots.The crosswalks connecting to the central islands,normally full of pedestrians,have negative impact on roundabout capability and pedestrian safety.Therefore,this study proposes a fuzzy cellular automata(FCA)model to explore the safety and efficiency impacts of pedestrian-vehicle conflicts at a two-lane roundabout.To reason the decision-making process of individual drivers before crosswalks,membership functions in the fuzzy inference system were calibrated with field data conducted in Changsha,China.Using specific indicators of efficiency and safety performance,it was shown that circulating vehicles can move smoothly in low traffic flow,but the roundabout system is prone to the traffic congestion if traffic flow reaches to a certain level.Also,the high yielding rate of drivers has a negative impact on the traffic efficiency but can improve pedestrian safety.Furthermore,a pedestrian restriction measure was deduced for the roundabout crosswalk from the FCA model and national guideline of setting traffic lights.展开更多
Genetic parameters for milk,fat yield and age at first calving of Chinese Holsteins in Heilongjiang were evaluated using multiple trait restricted maximum likelihood procedures with an animal model.Data consisted of ...Genetic parameters for milk,fat yield and age at first calving of Chinese Holsteins in Heilongjiang were evaluated using multiple trait restricted maximum likelihood procedures with an animal model.Data consisted of records of 2496 Chinese Holsteins first lactation cows collected from 1989 to 2000.The model included 21 herd effects,four calving season effects,nine age at first calving effects,6697 animal effects.(Co)variance components of milk yield,fat yield and age at first calving were estimated with the software package for variance component estimation(VCE) by an animal model. The heritabilities were 0.14,0.21,0.38 for milk yield,fat yield and age at first calving,respectively.The estimates of genetic correlation between milk yield and fat yield,age at first calving were 0.96,-0.29,respectively.The estimate of genetic correlation between fat yield and age at first calving was -0.28.展开更多
A novel multi-observer passive localization algorithm based on the weighted restricted total least square （WRTLS） is proposed to solve the bearings-only localization problem in the presence of observer position erro...A novel multi-observer passive localization algorithm based on the weighted restricted total least square （WRTLS） is proposed to solve the bearings-only localization problem in the presence of observer position errors. Firstly, the unknown matrix perturbation information is utilized to form the WRTLS problem. Then, the corresponding constrained optimization problem is transformed into an unconstrained one, which is a generalized Rayleigh quotient minimization problem. Thus, the solution can be got through the generalized eigenvalue decomposition and requires no initial state guess process. Simulation results indicate that the proposed algorithm can approach the Cramer-Rao lower bound （CRLB）, and the localization solution is asymptotically unbiased.展开更多
Along with the rapid advance of industrialization and urbanization process, fostering new agricultural business entities become inevitable for agricultural transformation and the construction of agricultural moderniza...Along with the rapid advance of industrialization and urbanization process, fostering new agricultural business entities become inevitable for agricultural transformation and the construction of agricultural modernization in China. The status of the new agricultural business entities determines the level of modern agricultural development. In recent years, new agricultural business entities have grew rapidly. However, there are still many problems including the difficulties in financing loans, inadequate agricultural insurance system, bad implementation of agricultural subsidies, jagged agricultural talents and so on. In order to foster new agricultural business entities, countermeasures should be carried out to ensure financial support, perfect the agricultural insurance, strengthen the level of agricultural subsidies, strive to develop the degree of specialization agricultural operators and so on.展开更多
基金Projects(71171200,51108465,71101155)supported by the National Natural Science Foundation of China
文摘An optimization model and its solution algorithm for alternate traffic restriction(ATR) schemes were introduced in terms of both the restriction districts and the proportion of restricted automobiles. A bi-level programming model was proposed to model the ATR scheme optimization problem by aiming at consumer surplus maximization and overload flow minimization at the upper-level model. At the lower-level model, elastic demand, mode choice and multi-class user equilibrium assignment were synthetically optimized. A genetic algorithm involving prolonging codes was constructed, demonstrating high computing efficiency in that it dynamically includes newly-appearing overload links in the codes so as to reduce the subsequent searching range. Moreover,practical processing approaches were suggested, which may improve the operability of the model-based solutions.
文摘Background The aggravating trend of aging population has brought us with great medical challenges. Calorie restriction （CR） has various beneficial effects on health, including lifespan prolongation and functional im- provement of multiple organisms. SIRT6, a member of the Sirtuin family of NAD^＋-dependent histone deacetylases, has been shown to play a key role in mediating the effects of CR. Aim Here we show how CR-triggered SIRT6-de- pendent pathways affect aging and the critical role of SIRT6 on inflammation. Methods 24-month-old mice were fed under ad libitum （AL） or CR condition for 6 months to determine the effects of CR. In addition, we took low glucose （LG） cultured WI38 human fibroblasts as a model to mimic CR in vitro. Further more, we stably overex- pressed or knockdown SIRT6 in WI38 to identify the role of SIRT6 in cell senescence and inflammation. Results Aged mice with CR had improved renal pathology and enhanced SIRT6 expression compared with AL group. In ad- dition, compared with normal glucose （NG） group, LG group had prolonged lifespan and increased expression of SIRT6. Furthermore, increased SA-β-gal positive cells were observed in SIRT6-deficient cells while the overexpres- sion of SIRT6 could delay the replicative senescence effectively. NF-KB was involved in the SIRT6 mediated lon- gevity control. SIRT6 overexpressed WI38 had low translocate rate of NF-KB into the nucleus and SIRT6 could at- tenuate the NF-KB signaling by deacetylating the RelA subunit of NF-KB complex. Conclusion In this study, we show that CR prevents age-dependent renal insufficiency by up-regulation of SIRT6. CR-triggered SIRT6 activation suppresses NF-KB signaling via preventing nuclear translocation of NF-KB. Here we identified the beneficial effects of CR on renal aging and determined the crucial role of SIRT6 on CR-mediated lifespan extension.
文摘Restriction enzyme digestion of total genomic DNA of two chro-mosome type Paragonimus westermani showed the presence of homologus highlyrepeated DNA in diploid and triploid forms. Southern blot analysis providedfurther evidence that the distribution of restriction enzyme sites (with 3enzymes) on repeated DNA of both was similar. But with Pst Ⅰ、Dde Ⅰ、Hae Ⅲand Hpa Ⅱ. They revealed polymorphism which also occured individually ineach form tested separatedly with hybridization technique. Mutation of recog-nize sites by enzymes, which is resulted from the alternation of gene sequance,has occured during evolution. Additionally, it is probably possible, based on PstⅠand Dde Ⅰdigest pattern to distinguish between diploid and triploid Parag-onimus westermani and group the Paragonimus simply and rapidly.
基金Supported by the Education Department Research Program of Heilongjiang Province(12531036)Doctor Science Foundation of Northeast Agricultural University(2009RC28)
文摘The study was carried out to investigate the effects of maternal dietary energy restriction on growth performance, serum indices and fat deposition of offspring. A total of 400 female Arbor Acres （AA） broiler breeders were studied. These female birds involved three experimental treatments and a control group with normal dietary energy diets （ND, 11.7 MJ of ME. kgt during the laying）. In treatments 2, 3 and 4, the energies of diets were 20%, 30% and 50% （LD20, LD30 and LD50） lower than those of the control, respectively. The study commenced at the beginning of the laying period when the total egg production reached 5% of the flock. All the broiler offspring were fed the same diets. The results showed that in low energy diets, offspring showed decreased 1-day-old weight, but 49-day-old weight was higher in LD20 diet （P〈0.05）. For offspring during days 1-49, the average daily gain （ADG） in LD20 group and the feed conversion ratio in LD50 group were improved as compared with those of the control （P〈0.05）. Compared with the control, abdominal fat percentage increased in 49-day-old offspring from LD30 diet （P〈0.05）; the fat content of breast muscle in offspring increased in broilers fed low energy diets （P〈0.05）. In 28-day-old offspring from breeders given LD20 and LD50 diets, liver fat percentages were higher compared with ND （P〈0.05）. The subcutaneous fat thickness in 28-day-old offspring from LD50 group and 49-day-old offspring from LD30 group was higher （P〈0.05）. On day 49, the serum cholesterol （CHO） of offspring from breeders fed LD20 diet and serum high-density lipoprotein （HDL） of offspring from breeders fed LD50 diet reduced compared with those of the control （P〈0.05）. In addition, a higher triiodothyronine （T3） content in serum was found in offspring from broiler breeders given LD20 and LD30 diets （P〈0.05）. Serum thyroxine （T4） in offspring significantly decreased with the decrease of diet energy （P〈0.05）. In conclusion, to a certain extent, dietary energy restriction in breeders could improve growth performance and promote lipid metabolism of offspring.
基金National Basic Research Programof China (2004|CB11750-5)
文摘An experiment was conducted to study the influence of eady quantitative feed restriction on the performance and carcass characteristics of broiler chickens. Two hundred 8-day-old commercial Avian male broiler chicks were assigned to four groups randomly, with 50 broilers each. At the age of 8 days the broilers were restricted to 90%, 80% or 70% of the ad libitum intake for 7 days. When the restricion was finished, all birds received feed ad libitum again. The results showed that diet restriction resulted in a reduction in body weight and daily gain during the restriction period （P 〈0.05）. The birds restricted to 90% of the ad libitum intake showed the occurring of growth compensation in the 3rd week. The birds restricted to 80% and 70% of the ad libitum intake had growth compensation in the 4th week. No significant differences between the effects of the restriction and the control on final body weight, growth rate, feed conversion efficiency and carcass characteristics （P 〈0.05）.
文摘The patterns of cleavage of mtDNA by restriction endonucleases was analysed for six fowl breeds and of. Hyline White, Hyline Brown, ISA Brown, Hisex Brown, Lohmann White, Abor Acres and mtDNA polymorphisms were detected in the restriction patterns with the following eight enzymes, Ava Ⅰ, Ava Ⅱ, EcoR Ⅰ, Hind Ⅲ, Bam HI, Pvu Ⅱ, Pst Ⅰ, Hinc Ⅱ. The restriction cleavage patterns were identical among these breeds. Hyline White, Hyline Brown, ISA Brown, Hisex Brown, Lohmann White—A type. The patterns of Abor Acres were B type. Based on their mtDNA restriction types, all the breeds were classified into two groups. Genetic distances among these groups were calculated in order to define their phylogenetic relationships. The relationship among five egg line breeds is close, while Abor Acres (Broiler fowl) is relatively far from them. The results suggest that the difference of mtDNA could result from the different origins. The polymorphic sites in mtDNA of Hyline White has been located on a restriction map.
基金the support of the National Natural Science Foundation of China(Grant No.62076204)the Seed Foundation of Innovation and Creation for Graduate Students in Northwestern Polytechnical University(Grant No.CX2020019)in part by the China Postdoctoral Science Foundation(Grants No.2021M700337)。
文摘Improvement of integrated battlefield situational awareness in complex environments involving dynamic factors such as restricted communications and electromagnetic interference(EMI)has become a contentious research problem.In certain mission environments,due to the impact of many interference sources on real-time communication or mission requirements such as the need to implement communication regulations,the mission stages are represented as a dynamic combination of several communication-available and communication-unavailable stages.Furthermore,the data interaction between unmanned aerial vehicles(UAVs)can only be performed in specific communication-available stages.Traditional cooperative search algorithms cannot handle such situations well.To solve this problem,this study constructed a distributed model predictive control(DMPC)architecture for a collaborative control of UAVs and used the Voronoi diagram generation method to re-plan the search areas of all UAVs in real time to avoid repetition of search areas and UAV collisions while improving the search efficiency and safety factor.An attention mechanism ant-colony optimization(AACO)algorithm is proposed for UAV search-control decision planning.The search strategy is adaptively updated by introducing an attention mechanism for regular instruction information,a priori information,and emergent information of the mission to satisfy different search expectations to the maximum extent.Simulation results show that the proposed algorithm achieves better search performance than traditional algorithms in restricted communication constraint scenarios.
文摘A novel coronavirus, severe acute respiratory syndrome (SA RS)-associated coronavirus (SARS-CoV), has been identified as the causal agent of SARS. Spike (S) protein is a major structural glycoprotein of the SARS virus and a potential target for SARS-specific cell-mediated immune responses. A pa nel of S protein-derived peptides was tested for their binding affinity to HLA -A *0201 molecules. Peptides with high affinity for HLA-A *0201 were then as se ssed for their capacity to elicit specific immune responses mediated by cytotoxi c T lymphocytes (CTLs) both in vivo, in HLA-A2.1/K b transgenic mice, a nd in vitro, from peripheral blood lymphocytes (PBLs) harvested from healthy HLA-A 2.1 + donors. SARS-CoV protein-derived peptide-1 (SSp-1 RLNEVAKNL), induced pepti de-specific CTLs both in vivo (transgenic mice) and in vitro (human PBL s), which specifically released interferon-gamma (IFN-gamma) upon stimulation with SSp-1-pulsed autologous dendritic cells (DCs) or T2 cells. SSp-1-specif ic CTLs also lysed major histocompatibility complex (MHC)-matched tumor cell lines engineered to express S proteins. HLA-A *0201-SSp-1 tetramer staining re vealed the presence of significant populations of SSp-1-specific CTLs in SSp- 1-induced CD8 + T cells. We propose that the newly identified epitope SSp-1 w ill help in the characterization of virus control mechanisms and immunopathology in SARS-CoV infection, and may be relevant to the development of immunotherape utic approaches for SARS.
文摘A wide variety of human tumors express interleukin10 (IL-10) for reasons poorly understood. We haveanalysed the effect of spontaneous IL-10 expression by amouse tumor (J558L) on its immunparalysing effect.Because cross-priming" of T cells by host antigenpresenting cells for MHC class I restricted tumor antigensis a major pathway for induction of tumor immunity andthat is enhanced by granulocyte-macrophage colony-stimulating factor (GM-CSF), we expressed this cytokinein J558L cells. GM-CSF secreting cells were not
基金This work was funded by the National Natural Science Foundation of China(No.51576188).
文摘Compared with the conventionally gaseous or liquid working media,the specific internal energy of supercritical carbon dioxide(SCD)is higher at the same temperature and pressure,and the critical temperature of carbon dioxide is close to room temperature,making SCD a potential new working medium for pneumatic launch.To analyze the feasibility of this conception,an analytical model of a pneumatic catapult is established on basis of the conservations of mass and energy.The model consists of a high-pressure chamber and a low-pressure chamber connected by multiple valves,and there is a movable piston in the low-pressure chamber that can push an aircraft to accelerate.The effects of the launch readiness state of SCD in the high-pressure chamber,the initial volume of the low-pressure chamber and the valve control on the movement of the aircraft are analyzed.It is found that there is a restrictive relation between the temperature and pressure of the launch readiness state of SCD,i.e.,there is a maximum allowable launch readiness pressure when the launch readiness temperature is fixed.If this restrictive relation is not satisfied,the working medium in the low-pressure chamber will drop to its triple point within a few milliseconds,leading to a launch failure.Owing to this restrictive relation,there is an optimal launch readiness state of SCD with the highest working capacity for any allowable launch readiness temperature.The pressure of the low-pressure chamber will decrease significantly as the initial volume increases,leading to a decreased acceleration of the aircraft.The acceleration can be controlled below a critical value by a designed sequential blasting technique of multiple valves.The calculated results show that a 500 kg aircraft can be accelerated from 0 to 58 m/s in 0.9 s with 36 kg of carbon dioxide.This research provides a new technique for the controllable cold launch of an aircraft.
文摘Solving the financing problem in rural areas and improving the level of economic development in rural areas become important guarantees for the expansion of domestic demand. This research, through studying the current situation of rural financing, pointed out the main factors restricting the financing in rural areas, such as high risk credit, slow income growth, high financing cost and difficult mortgage and guaranteed loans. Based on those, the author worked out the objectives and direction of China＇s rural financing reform, from two aspects of path selection of reform and innovation and specific embodiments for adjusting the overall reconstruction, and put forward some relevant countermeasures.
文摘This review article aims to give a comprehensive review of periodic orbits in the circular restricted three-body problem(CRTBP),which is a standard ideal model for the Earth-Moon system and is closest to the practical mechanical model.It focuses the attention on periodic orbits in the Earth-Moon system.This work is primarily motivated by a series of missions and plans that take advantages of the three-body periodic orbits near the libration points or around two gravitational celestial bodies.Firstly,simple periodic orbits and their classification that is usually considered to be early work before 1970 are summarized,and periodic orbits around Lagrange points,either planar or three-dimensional,are intensively studied during past decades.Subsequently,stability index of a periodic orbit and bifurcation analysis are presented,which demonstrate a guideline to find more periodic orbits inspired by bifurcation signals.Then,the practical techniques for computing a wide range of periodic orbits and associated quasi-periodic orbits,as well as constructing database of periodic orbits by numerical searching techniques are also presented.For those unstable periodic orbits,the station keeping maneuvers are reviewed.Finally,the applications of periodic orbits are presented,including those in practical missions,under consideration,and still in conceptual design stage.This review article has the function of bridging between engineers and researchers,so as to make it more convenient and faster for engineers to understand the complex restricted three-body problem(RTBP).At the same time,it can also provide some technical thinking for general researchers.
基金Project(2020YFB1600400)supported by the National Key Research and Development Program of ChinaProject(2019JJ50837)supported by the Natural Science Foundation of Hunan Province,ChinaProject(71801227)supported by the National Natural Science Foundation of China。
文摘The roundabouts are widely used in China,some of which have central islands as scenic spots.The crosswalks connecting to the central islands,normally full of pedestrians,have negative impact on roundabout capability and pedestrian safety.Therefore,this study proposes a fuzzy cellular automata(FCA)model to explore the safety and efficiency impacts of pedestrian-vehicle conflicts at a two-lane roundabout.To reason the decision-making process of individual drivers before crosswalks,membership functions in the fuzzy inference system were calibrated with field data conducted in Changsha,China.Using specific indicators of efficiency and safety performance,it was shown that circulating vehicles can move smoothly in low traffic flow,but the roundabout system is prone to the traffic congestion if traffic flow reaches to a certain level.Also,the high yielding rate of drivers has a negative impact on the traffic efficiency but can improve pedestrian safety.Furthermore,a pedestrian restriction measure was deduced for the roundabout crosswalk from the FCA model and national guideline of setting traffic lights.
文摘Genetic parameters for milk,fat yield and age at first calving of Chinese Holsteins in Heilongjiang were evaluated using multiple trait restricted maximum likelihood procedures with an animal model.Data consisted of records of 2496 Chinese Holsteins first lactation cows collected from 1989 to 2000.The model included 21 herd effects,four calving season effects,nine age at first calving effects,6697 animal effects.(Co)variance components of milk yield,fat yield and age at first calving were estimated with the software package for variance component estimation(VCE) by an animal model. The heritabilities were 0.14,0.21,0.38 for milk yield,fat yield and age at first calving,respectively.The estimates of genetic correlation between milk yield and fat yield,age at first calving were 0.96,-0.29,respectively.The estimate of genetic correlation between fat yield and age at first calving was -0.28.
基金supported by the Aeronautical Science Foundation of China (20105584004)the Science and Technology on Avionics Integration Laboratory
文摘A novel multi-observer passive localization algorithm based on the weighted restricted total least square （WRTLS） is proposed to solve the bearings-only localization problem in the presence of observer position errors. Firstly, the unknown matrix perturbation information is utilized to form the WRTLS problem. Then, the corresponding constrained optimization problem is transformed into an unconstrained one, which is a generalized Rayleigh quotient minimization problem. Thus, the solution can be got through the generalized eigenvalue decomposition and requires no initial state guess process. Simulation results indicate that the proposed algorithm can approach the Cramer-Rao lower bound （CRLB）, and the localization solution is asymptotically unbiased.
基金Supported by the National Social Science Fund(13CJY079)the National Natural Science Fund(71303039)
文摘Along with the rapid advance of industrialization and urbanization process, fostering new agricultural business entities become inevitable for agricultural transformation and the construction of agricultural modernization in China. The status of the new agricultural business entities determines the level of modern agricultural development. In recent years, new agricultural business entities have grew rapidly. However, there are still many problems including the difficulties in financing loans, inadequate agricultural insurance system, bad implementation of agricultural subsidies, jagged agricultural talents and so on. In order to foster new agricultural business entities, countermeasures should be carried out to ensure financial support, perfect the agricultural insurance, strengthen the level of agricultural subsidies, strive to develop the degree of specialization agricultural operators and so on.
