Apolipoprotein E has diverse functions in neurons:Apolipoprotein E(ApoE)is a glycoprotein that primarily regulates lipid metabolism and transport in the central nervous system.There are three predominant human ApoE pr...Apolipoprotein E has diverse functions in neurons:Apolipoprotein E(ApoE)is a glycoprotein that primarily regulates lipid metabolism and transport in the central nervous system.There are three predominant human ApoE protein isoforms with cysteine and arginine substitutions at amino acid positions 112 and 158 that impact their lipidation and related functions(Flowers and Rebeck,2020).ApoE2 is characterized by Cys112 and Cys158,ApoE3 by Cys112 and Arg158,whereas ApoE4 contains Arg112 and Arg158.展开更多
“Inf luenced by the slow recover y of the globa l economy,the continual impact of El Niño,growing local conflicts,the prevalence of trade protectionism and other factors,this year,the global supply and demand fo...“Inf luenced by the slow recover y of the globa l economy,the continual impact of El Niño,growing local conflicts,the prevalence of trade protectionism and other factors,this year,the global supply and demand for agricultural products and trade is under pressure,and the world’s food security has been a serious challenge.Therefore,it is of great and far-reaching significance for all countries in the world to further develop international cooperation in agriculture from a strategic height,in order to maintain the resilience of the international supply chain of agriculture,and to promote mutual benefits and the common development of all parties.”Yu Jianlong,Vice President of China Council for the Promotion of International Trade(CCPIT)and Vice President of the China Chamber of International Commerce(CCIC),said at the 2024 China Agricultural Conference for International Economic and Trade Cooperation.展开更多
Two recent trips to cities in China got me thinking a lot about China’s development and efforts to maintain its identity.While China is developing with strong momentum in every sector,it has succeeded at preserving a...Two recent trips to cities in China got me thinking a lot about China’s development and efforts to maintain its identity.While China is developing with strong momentum in every sector,it has succeeded at preserving and upholding its ancient traditions and customs.These trips showed me a country not only keen on technological and infrastructural advancement but also deeply committed to cultural preservation and promotion.In every corner of these cities,I witnessed a harmonious blend of the old and new,a testament to China’s dedication to maintaining its cultural heritage while embracing modernity.展开更多
Bone formation is a highly energy-demanding process that can be impacted by metabolic disorders.Glucose has been considered the principal substrate for osteoblasts,although fatty acids are also important for osteoblas...Bone formation is a highly energy-demanding process that can be impacted by metabolic disorders.Glucose has been considered the principal substrate for osteoblasts,although fatty acids are also important for osteoblast function.Here,we report that osteoblasts can derive energy from endogenous fatty acids stored in lipid droplets via lipolysis and that this process is critical for bone formation.As such,we demonstrate that osteoblasts accumulate lipid droplets that are highly dynamic and provide the molecular mechanism by which they serve as a fuel source for energy generation during osteoblast maturation.Inhibiting cytoplasmic lipolysis leads to both an increase in lipid droplet size in osteoblasts and an impairment in osteoblast function.The fatty acids released by lipolysis from these lipid droplets become critical for cellular energy production as cellular energetics shifts towards oxidative phosphorylation during nutrient-depleted conditions.In vivo,conditional deletion of the ATGL-encoding gene Pnpla2 in osteoblast progenitor cells reduces cortical and trabecular bone parameters and alters skeletal lipid metabolism.Collectively,our data demonstrate that osteoblasts store fatty acids in the form of lipid droplets,which are released via lipolysis to support cellular bioenergetic status when nutrients are limited.Perturbations in this process result in impairment of bone formation,specifically reducing ATP production and overall osteoblast function.展开更多
After harvest,potato tubers undergo an important period of dormancy,which significantly impacts potato quality and seed vigor.StSN2 has been reported as a key gene for maintaining tuber dormancy;in this study,we explo...After harvest,potato tubers undergo an important period of dormancy,which significantly impacts potato quality and seed vigor.StSN2 has been reported as a key gene for maintaining tuber dormancy;in this study,we explored the molecular mechanism by which StSN2 maintains dormancy.StBIN2 was first identified as a candidate protein that interacts with StSN2 by co-immunoprecipitation/mass spectrometry,and both qPCR and enzyme activity experiments showed that StSN2 can promote the StBIN2 expression and activity.In addition,the interaction between StSN2 and StBIN2 was verified by yeast two-hybrid,luciferase complementation experiments and co-immunoprecipitation.Bioinformatics analysis and site-directed mutagenesis confirmed the critical role of cysteine residues of StBIN2 in its binding to StSN2.Similar to that of StSN2,overexpression of StBIN2 extended the dormancy of potato tuber.Interaction between StSN2 and StBIN2 increased the activity of the StBIN2 enzyme,inhibited the expression of StBZR1,and suppressed BR signaling.On the contrary,this interaction promoted the expression of StSnRK2.2/2.3/2.4/2.6 and StABI5,key genes of ABA signaling,and the phosphorylation of StSnRK2.3,thereby promoting ABA signaling.Altogether,our results indicate that StSN2 interacts with StBIN2 through key cysteine residues and StBIN2 maintains tuber dormancy by affecting ABA and BR signaling.Findings of this research offer new insights into the molecular mechanism by which StSN2 maintains potato tuber dormancy through interaction with StSIN2 and provide guidance for potato improvement.展开更多
Purpose: The present study aimed to evaluate the effects of thermal aging on the shear bond strength of three different types of cement used to retain band and loop space maintainers cemented on extracted human perman...Purpose: The present study aimed to evaluate the effects of thermal aging on the shear bond strength of three different types of cement used to retain band and loop space maintainers cemented on extracted human permanent molar teeth. Methods: A total of 66 newly extracted permanent molars were used in this study. Eighteen teeth were used as a control and did not undergo thermal aging (six per group). All sample teeth were randomly divided into three groups: KetacCem, RelyX Luting Plus, and RelyX Unicem 2. After bonding procedures, all experimental groups undergo thermal aging. The shear bond strength of all samples was conducted using the Ultratester machine. Findings were statistically analyzed using the ANOVA and Turkey’s post hoc tests. Results: Among the examined groups, Ketac Cem presented with the highest recorded shear bond (11.4 MPa), while RelyX Luting Plus showed the lowest (3.2 MPa). The control groups recorded the highest shear bond strength compared to all examined groups;Ketac Cem showed the highest shear bond strength (12.8 Mpa), and RelyX Luting Plus had the least recorded reading (5.4 Mpa). Conclusion: Within the limitation of the present study, there was a statistically significant difference between the examined groups;Ketac Cem showed a higher shear bond cement than RelyX luting Plus and RelyX Unicem.展开更多
Eating a meal normally doesn’t trigger an inflammatory immune reaction,but how the body maintains tolerance to food has been unclear.Now,a new study published in Cell(doi:10.1016/j.cell.2023.05.027)by scientists at t...Eating a meal normally doesn’t trigger an inflammatory immune reaction,but how the body maintains tolerance to food has been unclear.Now,a new study published in Cell(doi:10.1016/j.cell.2023.05.027)by scientists at the University of Science and Technology of China(USTC)and Yale University School of Medicine reveals an unexpected role of a protein called gasdermin D(GSDMD)in inducing immune tolerance to food in the small intestine.展开更多
From December 2 to 4,2022,Guangzhou hosted the 19th International Finance Forum(IFF)annual meeting,themed“The Ever-Changing World:Reshaping Our Shared Future.”The event was attended by leaders of world organizations...From December 2 to 4,2022,Guangzhou hosted the 19th International Finance Forum(IFF)annual meeting,themed“The Ever-Changing World:Reshaping Our Shared Future.”The event was attended by leaders of world organizations including the United Nations,the International Monetary Fund,and the World Bank.展开更多
Maintainability influencing attributes are analyzed, their weight and value calculating methods are given, and the maintainability fuzzy evaluation method is proposed based on the relative closeness. According to the ...Maintainability influencing attributes are analyzed, their weight and value calculating methods are given, and the maintainability fuzzy evaluation method is proposed based on the relative closeness. According to the maintenance task simulation operated in virtual environment, the maintainability virtual evaluation model is built by analyzing the maintenance task for each replaceable unit of product. At last, a case study is given based upon the main landing gear system of a certain type civil aircraft, and the result indicates that the model is suitable for maintainability qualitative evaluation and can support maintainability concurrent design.展开更多
This paper uses three size metrics,which are collectable during the design phase,to analyze the potentially confounding effect of class size on the associations between object-oriented（OO）metrics and maintainability...This paper uses three size metrics,which are collectable during the design phase,to analyze the potentially confounding effect of class size on the associations between object-oriented（OO）metrics and maintainability.To draw as many general conclusions as possible,the confounding effect of class size is analyzed on 127 C＋＋ systems and 113 Java systems.For each OO metric,the indirect effect that represents the distortion of the association caused by class size and its variance for individual systems is first computed.Then,a statistical meta-analysis technique is used to compute the average indirect effect over all the systems and to determine if it is significantly different from zero.The experimental results show that the confounding effects of class size on the associations between OO metrics and maintainability generally exist,regardless of whatever size metric is used.Therefore,empirical studies validating OO metrics on maintainability should consider class size as a confounding variable.展开更多
Maintainability is an important design characterist ic , and also is a design parameter. The essence of maintainability design is to ex pect and solve possible maintenance problems at early stage during product devel ...Maintainability is an important design characterist ic , and also is a design parameter. The essence of maintainability design is to ex pect and solve possible maintenance problems at early stage during product devel opment, maintainability must be designed into product simultaneously. But curren t maintainability methods do not support concurrent engineering. This paper anal yzes the deficiencies of existing maintainability technologies, and introduces t he concept of maintainability analysis visualization. The two major deficiencies are that maintainability analysis time lags behind product design, and the main tainability techniques do not accommodate modern product design concepts. After this, the infrastructure of maintainability analysis visualization system is dis cussed. The system are composed of four subsystems, they are product modeling, d isassembly process modeling, simulation and analysis, and user interface. Produc t modeling is accomplished with the capability of CAD system, disassembly proces s modeling is mainly a reason process based on assembly information. The system is integrated into AutoCAD so that designer can timely analyze their product des ign from the viewpoint of easy maintenance. Human model generation function, hum an task analysis function, tool analysis function, visibility analysis function is implemented, disassembly process planning function is still under developing.展开更多
As one of the most important attributes of software quality, software maintainability has been widely recognized.However,the existing maintainability evaluation methods are mostly based on subjectively judgment. Thus ...As one of the most important attributes of software quality, software maintainability has been widely recognized.However,the existing maintainability evaluation methods are mostly based on subjectively judgment. Thus it is inapplicable or unbelievable. To evaluate software maintainability objectively,the software configuration management( SCM) data are collected to establish a maintainability model. Based on the hidden Markov chain( HMC), a three-state maintainability estimation model is constructed. To validate the feasibility of the model,a real software example of software maintenance activity is given and the result from the example shows the effectiveness of the proposed method.展开更多
The basis of the two guideline lectures for maintainability design, namely''maintainability design criterions'' and ''cases compilation of maintainability design technique'' , anintelle...The basis of the two guideline lectures for maintainability design, namely''maintainability design criterions'' and ''cases compilation of maintainability design technique'' , anintellectualized architecture for combining rule-based reasoning (RBR) and case-based reasoning(CBR), is presented in this paper by analyzing from maintainability design procedure to the thoughtof our solving the maintainability design problem. Furthermore, the domain model and reasoningprocess is introduced and a representation of maintainability domain knowledge is given. Finally,the computer-aided engineering system for maintainability design (MCAES) which is based onintellectualized architecture is reported; its function and implementation is described.展开更多
The on-going Coronavirus disease(COVID-19)outbreak in China has become the world's leading health headline and is causing major panic and public concerns.On January 30,2020,the World Health Organization(WHO)declar...The on-going Coronavirus disease(COVID-19)outbreak in China has become the world's leading health headline and is causing major panic and public concerns.On January 30,2020,the World Health Organization(WHO)declared that the new coronavirus outbreak is a public health emergency of international concern.1 The virus has already had a direct impact on more than 10 million people in the city of Wuhan and has reached other parts of China as well,posing a health threat of unknown magnitude globally.As of February 8,2020,WHO reported 34,886 confirmed cases of COVID-19 globally,with 34,589 of them occurring in China(including 6101 severe cases and 723 deaths).A total of 288 other confirmed cases(with 1 death)have been reported in 24 countries,including Japan,Australia,Germany,and United States.2 However,these daily estimates are expected to rise even higher as reports from health authorities in China3 are gathered and near real-time updates of the Johns Hopkins virus dashboard are made 4 The outbreak has caused governments in various countries to take swift and protective measures.In China,these included putting cities on lockdown,5 implementing travel wamings/bans and cancellations,6 extending national holidays,and closing schools and postponing classes7.展开更多
Fifteen common rice maintainer lines and 26 high-yielding restorer lines were used to evaluate their thermal resistance and fertility during flowering and early grain filling stages. The rice plants were subjected to ...Fifteen common rice maintainer lines and 26 high-yielding restorer lines were used to evaluate their thermal resistance and fertility during flowering and early grain filling stages. The rice plants were subjected to high temperature stress （39-43 ℃） for 1-15 d from main stem flowering. Based on the heat stress index, they were divided into thermal resistant lines, semi-thermal resistant lines, semi-thermal sensitive lines and thermal sensitive lines. Therefore, the maintainer lines K22B, Bobai B and V20B belonged to thermal resistant lines, whereas 11-32B, Zhongzhe B and Zhong 9B belonged to thermal sensitive lines. For rice restorer lines, Minghui 63 had the highest thermal resistance, followed by R207, P32, P929, and the lowest thermal resistant lines P62-2-2, R8006 and P51. The correlation analysis indicated that the heat stress index was significantly correlated with seed-setting rate and abortive grain rate under heat stress, but not under natural conditions. This indicated that heat stress occurred during flowering and early grain filling stages mainly decreased the seed- setting rate and significantly increased the abortive grain rate in both rice maintainer and restorer lines.展开更多
Intervertebral disc （IVD） degeneration is the leading cause of disability with no disease-modifying treatment. IVD degeneration is associated with instable mechanical loading in the spine, but little is known about ...Intervertebral disc （IVD） degeneration is the leading cause of disability with no disease-modifying treatment. IVD degeneration is associated with instable mechanical loading in the spine, but little is known about how mechanical stress regulates nucleus notochordal （NC） cells to maintain IVD homeostasis. Here we report that mechanical stress can result in excessive integrin αvβ6-mediated activation of transforming growth factor beta （TGFβ）, decreased NC cell vacuoles, and increased matrix proteoglycan production, and results in degenerative disc disease （DDD）. Knockout of TGFβ type II receptor （TβRII） or integrin αv in the NC cells inhibited functional activity of postnatal NC cells and also resulted in DDD under mechanical loading. Administration of RGD peptide, TGFβ, and αvβ6-neutralizing antibodies attenuated IVD degeneration. Thus, integrin-mediated activation of TGFβ plays a critical role in mechanical signaling transduction to regulate IVD cell function and homeostasis. Manipulation of this signaling pathway may be a potential therapeutic target to modify DDD.展开更多
Reliability, maintainability and testability （RMT） are important properties of equipment, since they have important influ- ence on operational availability and life cycle costs （LCC）. There- fore, weighting and op...Reliability, maintainability and testability （RMT） are important properties of equipment, since they have important influ- ence on operational availability and life cycle costs （LCC）. There- fore, weighting and optimizing the three properties are of great significance. A new approach for optimization of RMT parameters is proposed. First of all, the model for the equipment operation pro- cess is established based on the generalized stochastic Petri nets （GSPN） theory. Then, by solving the GSPN model, the quantitative relationship between operational availability and RMT parameters is obtained. Afterwards, taking history data of similar equipment and operation process into consideration, a cost model of design, manufacture and maintenance is developed. Based on operational availability, the cost model and parameters ranges, an optimization model of RMT parameters is built. Finally, the effectiveness and practicability of this approach are validated through an example.展开更多
To improve the mainlainability design efficiency and quality, a layout optimization method for maintainability of multi-component systems was proposed. The impact of the component layout design on system maintainabili...To improve the mainlainability design efficiency and quality, a layout optimization method for maintainability of multi-component systems was proposed. The impact of the component layout design on system maintainability was analyzed, and the layout problem for maintainability was presented. It was formulated as an optimization problem, where maintainability, layout space and distance requirement were formulated as objective functions. A multi-objective particle swarm optimization algorithm, in which the constrained-domination relationship and the update strategy of the global best were simply modified, was then used to obtain Pareto optimal solutions for the maintainability layout design problem. Finally, application in oxygen generation system of a spacecraft was studied in detail to illustrate the effectiveness and usefulness of the proposed method. The results show that the concurrent maintainability design can be carried out during the layout design process by solving the layout optimization problem for maintainability.展开更多
Six isolates of Magnaporthe grisea were selected to inoculate on 10 Chinese leading maintainer lines (B-lines), 14 restorer lines (R-lines) and their F1 hybrid plants. In the tested rice materials, R-lines were proved...Six isolates of Magnaporthe grisea were selected to inoculate on 10 Chinese leading maintainer lines (B-lines), 14 restorer lines (R-lines) and their F1 hybrid plants. In the tested rice materials, R-lines were proved to be more resistant to blast than B-lines. The resistance frequency of about 25% F1 hybrid plants was less than their parents. In addition, 26 isolates of M. grisea collected from different rice growing areas of China were inoculated on 13 new improved hybrid rice combinations. The resistance frequencies of 5 improved hybrids were better than those of the controls and leading varieties in rice production of China.展开更多
This paper empirically investigates the relationships between 15 design metrics and maintainability of 148 Java open source software. The results show that size and complexity metrics are strongly related to the maint...This paper empirically investigates the relationships between 15 design metrics and maintainability of 148 Java open source software. The results show that size and complexity metrics are strongly related to the maintainability of open source software. However, cohesion and coupling, as currently captured by existing metrics, do not seem to have a significant impact on maintainability. When used together, these metrics can predict system maintainability fairly accurately （mean MREs below 30%）.展开更多
基金supported by core funding provided by Temasek Life Sciences Laboratory(to CTO)。
文摘Apolipoprotein E has diverse functions in neurons:Apolipoprotein E(ApoE)is a glycoprotein that primarily regulates lipid metabolism and transport in the central nervous system.There are three predominant human ApoE protein isoforms with cysteine and arginine substitutions at amino acid positions 112 and 158 that impact their lipidation and related functions(Flowers and Rebeck,2020).ApoE2 is characterized by Cys112 and Cys158,ApoE3 by Cys112 and Arg158,whereas ApoE4 contains Arg112 and Arg158.
文摘“Inf luenced by the slow recover y of the globa l economy,the continual impact of El Niño,growing local conflicts,the prevalence of trade protectionism and other factors,this year,the global supply and demand for agricultural products and trade is under pressure,and the world’s food security has been a serious challenge.Therefore,it is of great and far-reaching significance for all countries in the world to further develop international cooperation in agriculture from a strategic height,in order to maintain the resilience of the international supply chain of agriculture,and to promote mutual benefits and the common development of all parties.”Yu Jianlong,Vice President of China Council for the Promotion of International Trade(CCPIT)and Vice President of the China Chamber of International Commerce(CCIC),said at the 2024 China Agricultural Conference for International Economic and Trade Cooperation.
文摘Two recent trips to cities in China got me thinking a lot about China’s development and efforts to maintain its identity.While China is developing with strong momentum in every sector,it has succeeded at preserving and upholding its ancient traditions and customs.These trips showed me a country not only keen on technological and infrastructural advancement but also deeply committed to cultural preservation and promotion.In every corner of these cities,I witnessed a harmonious blend of the old and new,a testament to China’s dedication to maintaining its cultural heritage while embracing modernity.
基金supported by National Institutes of Health(NIH),the National Institute of Arthritis and Musculoskeletal and Skin Diseases(NIAMS)Grant K01AR072123(ER-R)the American Society of Bone and Mineral Research(ASBMR)Rising Star awardprovided by NIH-National Institute of Diabetes and Digestive and Kidney Disease(NIDDK)Grant DK116056(MPC)。
文摘Bone formation is a highly energy-demanding process that can be impacted by metabolic disorders.Glucose has been considered the principal substrate for osteoblasts,although fatty acids are also important for osteoblast function.Here,we report that osteoblasts can derive energy from endogenous fatty acids stored in lipid droplets via lipolysis and that this process is critical for bone formation.As such,we demonstrate that osteoblasts accumulate lipid droplets that are highly dynamic and provide the molecular mechanism by which they serve as a fuel source for energy generation during osteoblast maturation.Inhibiting cytoplasmic lipolysis leads to both an increase in lipid droplet size in osteoblasts and an impairment in osteoblast function.The fatty acids released by lipolysis from these lipid droplets become critical for cellular energy production as cellular energetics shifts towards oxidative phosphorylation during nutrient-depleted conditions.In vivo,conditional deletion of the ATGL-encoding gene Pnpla2 in osteoblast progenitor cells reduces cortical and trabecular bone parameters and alters skeletal lipid metabolism.Collectively,our data demonstrate that osteoblasts store fatty acids in the form of lipid droplets,which are released via lipolysis to support cellular bioenergetic status when nutrients are limited.Perturbations in this process result in impairment of bone formation,specifically reducing ATP production and overall osteoblast function.
基金This work was supported by the Innovation Team Project no.sccxtd-2023-09 of the Modern Agricultural Industrious Technology System of Sichuan Provincethe Biological Breeding Project no.SKL-ZY202203 of the State Key Laboratory of Crop Gene Exploration and Utilization in Southwest China.We thank A&L Scientific Editing(www.alpublish.com)for the linguistic assistance during the preparation of this manuscript.
文摘After harvest,potato tubers undergo an important period of dormancy,which significantly impacts potato quality and seed vigor.StSN2 has been reported as a key gene for maintaining tuber dormancy;in this study,we explored the molecular mechanism by which StSN2 maintains dormancy.StBIN2 was first identified as a candidate protein that interacts with StSN2 by co-immunoprecipitation/mass spectrometry,and both qPCR and enzyme activity experiments showed that StSN2 can promote the StBIN2 expression and activity.In addition,the interaction between StSN2 and StBIN2 was verified by yeast two-hybrid,luciferase complementation experiments and co-immunoprecipitation.Bioinformatics analysis and site-directed mutagenesis confirmed the critical role of cysteine residues of StBIN2 in its binding to StSN2.Similar to that of StSN2,overexpression of StBIN2 extended the dormancy of potato tuber.Interaction between StSN2 and StBIN2 increased the activity of the StBIN2 enzyme,inhibited the expression of StBZR1,and suppressed BR signaling.On the contrary,this interaction promoted the expression of StSnRK2.2/2.3/2.4/2.6 and StABI5,key genes of ABA signaling,and the phosphorylation of StSnRK2.3,thereby promoting ABA signaling.Altogether,our results indicate that StSN2 interacts with StBIN2 through key cysteine residues and StBIN2 maintains tuber dormancy by affecting ABA and BR signaling.Findings of this research offer new insights into the molecular mechanism by which StSN2 maintains potato tuber dormancy through interaction with StSIN2 and provide guidance for potato improvement.
文摘Purpose: The present study aimed to evaluate the effects of thermal aging on the shear bond strength of three different types of cement used to retain band and loop space maintainers cemented on extracted human permanent molar teeth. Methods: A total of 66 newly extracted permanent molars were used in this study. Eighteen teeth were used as a control and did not undergo thermal aging (six per group). All sample teeth were randomly divided into three groups: KetacCem, RelyX Luting Plus, and RelyX Unicem 2. After bonding procedures, all experimental groups undergo thermal aging. The shear bond strength of all samples was conducted using the Ultratester machine. Findings were statistically analyzed using the ANOVA and Turkey’s post hoc tests. Results: Among the examined groups, Ketac Cem presented with the highest recorded shear bond (11.4 MPa), while RelyX Luting Plus showed the lowest (3.2 MPa). The control groups recorded the highest shear bond strength compared to all examined groups;Ketac Cem showed the highest shear bond strength (12.8 Mpa), and RelyX Luting Plus had the least recorded reading (5.4 Mpa). Conclusion: Within the limitation of the present study, there was a statistically significant difference between the examined groups;Ketac Cem showed a higher shear bond cement than RelyX luting Plus and RelyX Unicem.
文摘Eating a meal normally doesn’t trigger an inflammatory immune reaction,but how the body maintains tolerance to food has been unclear.Now,a new study published in Cell(doi:10.1016/j.cell.2023.05.027)by scientists at the University of Science and Technology of China(USTC)and Yale University School of Medicine reveals an unexpected role of a protein called gasdermin D(GSDMD)in inducing immune tolerance to food in the small intestine.
文摘From December 2 to 4,2022,Guangzhou hosted the 19th International Finance Forum(IFF)annual meeting,themed“The Ever-Changing World:Reshaping Our Shared Future.”The event was attended by leaders of world organizations including the United Nations,the International Monetary Fund,and the World Bank.
基金National Natural Science Foundation of China-Joint Found of Civil Aviation Research (60572171)
文摘Maintainability influencing attributes are analyzed, their weight and value calculating methods are given, and the maintainability fuzzy evaluation method is proposed based on the relative closeness. According to the maintenance task simulation operated in virtual environment, the maintainability virtual evaluation model is built by analyzing the maintenance task for each replaceable unit of product. At last, a case study is given based upon the main landing gear system of a certain type civil aircraft, and the result indicates that the model is suitable for maintainability qualitative evaluation and can support maintainability concurrent design.
基金The National Natural Science Foundation of China(No.60425206,60633010)
文摘This paper uses three size metrics,which are collectable during the design phase,to analyze the potentially confounding effect of class size on the associations between object-oriented（OO）metrics and maintainability.To draw as many general conclusions as possible,the confounding effect of class size is analyzed on 127 C＋＋ systems and 113 Java systems.For each OO metric,the indirect effect that represents the distortion of the association caused by class size and its variance for individual systems is first computed.Then,a statistical meta-analysis technique is used to compute the average indirect effect over all the systems and to determine if it is significantly different from zero.The experimental results show that the confounding effects of class size on the associations between OO metrics and maintainability generally exist,regardless of whatever size metric is used.Therefore,empirical studies validating OO metrics on maintainability should consider class size as a confounding variable.
文摘Maintainability is an important design characterist ic , and also is a design parameter. The essence of maintainability design is to ex pect and solve possible maintenance problems at early stage during product devel opment, maintainability must be designed into product simultaneously. But curren t maintainability methods do not support concurrent engineering. This paper anal yzes the deficiencies of existing maintainability technologies, and introduces t he concept of maintainability analysis visualization. The two major deficiencies are that maintainability analysis time lags behind product design, and the main tainability techniques do not accommodate modern product design concepts. After this, the infrastructure of maintainability analysis visualization system is dis cussed. The system are composed of four subsystems, they are product modeling, d isassembly process modeling, simulation and analysis, and user interface. Produc t modeling is accomplished with the capability of CAD system, disassembly proces s modeling is mainly a reason process based on assembly information. The system is integrated into AutoCAD so that designer can timely analyze their product des ign from the viewpoint of easy maintenance. Human model generation function, hum an task analysis function, tool analysis function, visibility analysis function is implemented, disassembly process planning function is still under developing.
文摘As one of the most important attributes of software quality, software maintainability has been widely recognized.However,the existing maintainability evaluation methods are mostly based on subjectively judgment. Thus it is inapplicable or unbelievable. To evaluate software maintainability objectively,the software configuration management( SCM) data are collected to establish a maintainability model. Based on the hidden Markov chain( HMC), a three-state maintainability estimation model is constructed. To validate the feasibility of the model,a real software example of software maintenance activity is given and the result from the example shows the effectiveness of the proposed method.
文摘The basis of the two guideline lectures for maintainability design, namely''maintainability design criterions'' and ''cases compilation of maintainability design technique'' , anintellectualized architecture for combining rule-based reasoning (RBR) and case-based reasoning(CBR), is presented in this paper by analyzing from maintainability design procedure to the thoughtof our solving the maintainability design problem. Furthermore, the domain model and reasoningprocess is introduced and a representation of maintainability domain knowledge is given. Finally,the computer-aided engineering system for maintainability design (MCAES) which is based onintellectualized architecture is reported; its function and implementation is described.
文摘The on-going Coronavirus disease(COVID-19)outbreak in China has become the world's leading health headline and is causing major panic and public concerns.On January 30,2020,the World Health Organization(WHO)declared that the new coronavirus outbreak is a public health emergency of international concern.1 The virus has already had a direct impact on more than 10 million people in the city of Wuhan and has reached other parts of China as well,posing a health threat of unknown magnitude globally.As of February 8,2020,WHO reported 34,886 confirmed cases of COVID-19 globally,with 34,589 of them occurring in China(including 6101 severe cases and 723 deaths).A total of 288 other confirmed cases(with 1 death)have been reported in 24 countries,including Japan,Australia,Germany,and United States.2 However,these daily estimates are expected to rise even higher as reports from health authorities in China3 are gathered and near real-time updates of the Johns Hopkins virus dashboard are made 4 The outbreak has caused governments in various countries to take swift and protective measures.In China,these included putting cities on lockdown,5 implementing travel wamings/bans and cancellations,6 extending national holidays,and closing schools and postponing classes7.
基金supported by the National Natural Science Foundation of China(Grant Nos.30871473 and 31101116)the Project from the China National Rice Research Institute(Grant No.2009RG003-5)+1 种基金the Projects from local government of Zhejiang Province, China(Grant Nos.2008C22073,2009C32048 and SN200806)the Zhejiang Provincial Natural Science Foundation,China(Grant Nos.Y3100060 and Y3100090)
文摘Fifteen common rice maintainer lines and 26 high-yielding restorer lines were used to evaluate their thermal resistance and fertility during flowering and early grain filling stages. The rice plants were subjected to high temperature stress （39-43 ℃） for 1-15 d from main stem flowering. Based on the heat stress index, they were divided into thermal resistant lines, semi-thermal resistant lines, semi-thermal sensitive lines and thermal sensitive lines. Therefore, the maintainer lines K22B, Bobai B and V20B belonged to thermal resistant lines, whereas 11-32B, Zhongzhe B and Zhong 9B belonged to thermal sensitive lines. For rice restorer lines, Minghui 63 had the highest thermal resistance, followed by R207, P32, P929, and the lowest thermal resistant lines P62-2-2, R8006 and P51. The correlation analysis indicated that the heat stress index was significantly correlated with seed-setting rate and abortive grain rate under heat stress, but not under natural conditions. This indicated that heat stress occurred during flowering and early grain filling stages mainly decreased the seed- setting rate and significantly increased the abortive grain rate in both rice maintainer and restorer lines.
文摘Intervertebral disc （IVD） degeneration is the leading cause of disability with no disease-modifying treatment. IVD degeneration is associated with instable mechanical loading in the spine, but little is known about how mechanical stress regulates nucleus notochordal （NC） cells to maintain IVD homeostasis. Here we report that mechanical stress can result in excessive integrin αvβ6-mediated activation of transforming growth factor beta （TGFβ）, decreased NC cell vacuoles, and increased matrix proteoglycan production, and results in degenerative disc disease （DDD）. Knockout of TGFβ type II receptor （TβRII） or integrin αv in the NC cells inhibited functional activity of postnatal NC cells and also resulted in DDD under mechanical loading. Administration of RGD peptide, TGFβ, and αvβ6-neutralizing antibodies attenuated IVD degeneration. Thus, integrin-mediated activation of TGFβ plays a critical role in mechanical signaling transduction to regulate IVD cell function and homeostasis. Manipulation of this signaling pathway may be a potential therapeutic target to modify DDD.
文摘Reliability, maintainability and testability （RMT） are important properties of equipment, since they have important influ- ence on operational availability and life cycle costs （LCC）. There- fore, weighting and optimizing the three properties are of great significance. A new approach for optimization of RMT parameters is proposed. First of all, the model for the equipment operation pro- cess is established based on the generalized stochastic Petri nets （GSPN） theory. Then, by solving the GSPN model, the quantitative relationship between operational availability and RMT parameters is obtained. Afterwards, taking history data of similar equipment and operation process into consideration, a cost model of design, manufacture and maintenance is developed. Based on operational availability, the cost model and parameters ranges, an optimization model of RMT parameters is built. Finally, the effectiveness and practicability of this approach are validated through an example.
基金Project(51005238)supported by the National Natural Science Foundation of China
文摘To improve the mainlainability design efficiency and quality, a layout optimization method for maintainability of multi-component systems was proposed. The impact of the component layout design on system maintainability was analyzed, and the layout problem for maintainability was presented. It was formulated as an optimization problem, where maintainability, layout space and distance requirement were formulated as objective functions. A multi-objective particle swarm optimization algorithm, in which the constrained-domination relationship and the update strategy of the global best were simply modified, was then used to obtain Pareto optimal solutions for the maintainability layout design problem. Finally, application in oxygen generation system of a spacecraft was studied in detail to illustrate the effectiveness and usefulness of the proposed method. The results show that the concurrent maintainability design can be carried out during the layout design process by solving the layout optimization problem for maintainability.
文摘Six isolates of Magnaporthe grisea were selected to inoculate on 10 Chinese leading maintainer lines (B-lines), 14 restorer lines (R-lines) and their F1 hybrid plants. In the tested rice materials, R-lines were proved to be more resistant to blast than B-lines. The resistance frequency of about 25% F1 hybrid plants was less than their parents. In addition, 26 isolates of M. grisea collected from different rice growing areas of China were inoculated on 13 new improved hybrid rice combinations. The resistance frequencies of 5 improved hybrids were better than those of the controls and leading varieties in rice production of China.
基金Supported by the National Natural Science Foundation of China (60425206, 60633010)the High Technology Research Project of Jiangsu Province (BG2005032)the Specialized Research Fund for the Doctoral Program of Higher Education of China (20060286020)
文摘This paper empirically investigates the relationships between 15 design metrics and maintainability of 148 Java open source software. The results show that size and complexity metrics are strongly related to the maintainability of open source software. However, cohesion and coupling, as currently captured by existing metrics, do not seem to have a significant impact on maintainability. When used together, these metrics can predict system maintainability fairly accurately （mean MREs below 30%）.
