Fertility policies consist of not only the legal definition of"procreation",but also the"maternity"protection system,the complete set of selfconsistent social relations and policy systems formed ar...Fertility policies consist of not only the legal definition of"procreation",but also the"maternity"protection system,the complete set of selfconsistent social relations and policy systems formed around"fertility".Gender,labor and intergenerational relations are the cornerstones of a fertility policy system.In this framework,we focus on women of childbearing age as the main actors of reproductive behaviors,to research how drastic social changes have altered women,the above-mentioned relations,and policy support and analyze the structural factors that restrict women’s reproductive intentions.The traditional male breadwinner model,which can no longer prevail and the relatively slow development of maternity protection policies and service systems leave women of childbearing age in a dilemma between working hours and birth timing.Therefore,maternity protection policies should focus on improved decommodification of maternity insurance and the construction of women and children’s social welfare systems including childcare social service systems.展开更多
Gender discrimination has long been the problem that exists in the entire world,including China.However,as more and more people are focusing on the general gender discrimination,the group recognized an extension of su...Gender discrimination has long been the problem that exists in the entire world,including China.However,as more and more people are focusing on the general gender discrimination,the group recognized an extension of such discrimination-pregnancy discrimination in job hiring(the discrimination that women who are pregnant or have the inclination to pregnancy receive in hiring).The possible subtle pregnancy discrimination may be one of the main causes that lead to the declining fertility rate in China.The group decided to conduct an experiment to determine whether women are receiving more subtle discrimination in job hiring due to their identity as mother than men with children,men without children,and women without children.Using the form of questionary and resumes,the team found that Chinese women are indeed enduring subtle discrimination in work hiring.The experiment highlights the importance to promote further equality among women.However,there are some confounding variables,like the level of patient of the HR who reads the resume,affecting the ultimate result of the study.Keywords:gender discrimination,women’s career,Chinese job market,pregnancy discrimination,fertility rate in China.展开更多
This paper presented a novel variable rate fertilization system based on the method of adjusting the active feed-roll length of a fluted roller.The feasibility of this method was discussed using analysis of the fluted...This paper presented a novel variable rate fertilization system based on the method of adjusting the active feed-roll length of a fluted roller.The feasibility of this method was discussed using analysis of the fluted roller model.One seed drill produced by Kuhn Company(France),which could sow and fertilize simultaneously,was used as a test platform to implement the mechanical structure of variable rate fertilization.The design methods for the variable rate fertilization mechanical structure and actuator were introduced in detail.A low-cost and stable embedded support decision subsystem and corresponding software were developed.The support decision subsystem is based on grid management.Each grid field cell contains information about corresponding spatial position and fertilizer application rate.A SpatiaLite database was employed to solve the spatial location search and spatial data query.Experiments were conducted to evaluate the fertilization uniformity and dynamic response time.The average value of coefficient of variation is 8.4%in five different active feed-roll lengths which reflects good uniformity.The dynamic response times for the adjustment of variable rate fertilization system from 204 kg/hm^(2) to 319 kg/hm^(2) and 319 kg/hm^(2) to 204 kg/hm^(2) are about 4.2 s.The results suggest that the variable rate fertilization system performs well in dynamic adjustment and stability.展开更多
The key technical problem of variable rate fertilization system based on spectrum information was precise variable fertilization in certain area according to the acquired spectrum information.Hysteretic fertilizing is...The key technical problem of variable rate fertilization system based on spectrum information was precise variable fertilization in certain area according to the acquired spectrum information.Hysteretic fertilizing is a critical problem in most of current fertilizer equipment.Hysteresis model was built and analyzed in this study to improve the system.Fertilizing tests were conducted on different wheat breeds and the results were analyzed.The tests showed that variable rate fertilization had obvious hysteresis phenomenon with the maximum lag distance of 3.82 m,the minimum lag distance of 1.73 m and average of 3.06 m.Hysteresis phenomenon of the variable rate fertilization system was obviously decreased when implanting a correction time of 2.04 s with the maximum lag distance of 0.61 m.Variable effects varied by different wheat breeds.Variable rate fertilization had an advantage of improving spatial differences of Yangmai-23,and the spatial variability of which decreased by 14.23%.In the small test area,the amount of fertilizer in Zhenmai-168 decreased by 2.84 kg,while the amount of which in Yangmai-23 increased by 3.83 kg.Yield of Zhenmai-168 in small area was lower than that in traditional pattern,but the condition of Yangmai-23 was on the contrary.Valuable information for increasing performance of fertilization in variable rate fertilization system was provided in this paper.展开更多
In order to improve soil fertility and fertilizer utilization,a subsoiling variable rate fertilization machine based on conservation tillage and precision agriculture was designed and tested.The relationship between s...In order to improve soil fertility and fertilizer utilization,a subsoiling variable rate fertilization machine based on conservation tillage and precision agriculture was designed and tested.The relationship between suspension parameters and penetrating distance was analyzed,and a matching model between fertilizing quantity and penetrating distance was established.The variable rate fertilization control machine was developed based on an Advantech PCM-9363 industrial control mainboard.The machine operates under two patterns:DGPS-based positioning and straight-line path positioning based on a planar coordinate system.This machine can perform on-demand fertilization according to the spatial differences in soil nutrients and the prescription maps pre-set before the operation.Field experiments showed the machine has a subsoiling stability of 92.5%,a soil breaking rate of 61.1%,a maximum positioning relative error of 2.68%and a maximum variable rate fertilization error of 3.89%.The subsoiling performance and variable rate fertilization indices of this machine satisfy the requirements of GB/T24675.2-2009.The tested indices meet the national and industrial standards and satisfy the design requirements.The findings of the research can be used as the structural design of the subsoiling variable rate fertilization machine.展开更多
This paper first described the current status of wheat nitrogen fertilizers utilization rate. Then,from balanced fertilizer application,applying slow/controlled release fertilizer,deep application of nitrogen fertiliz...This paper first described the current status of wheat nitrogen fertilizers utilization rate. Then,from balanced fertilizer application,applying slow/controlled release fertilizer,deep application of nitrogen fertilizers and graded application,controlled application amount,selection of application time according to soil properties,diagnosed application of fertilizer with instrument,addition of synergist,and precise fertilizer application,it summarized biological nitrogen saving methods and introduced prospects of future biological nitrogen saving technology.展开更多
Our Fair Plan to Safeguard Earth’s Climate reduces the emission of greenhouse gases to zero over the 80-year time period 2020 to 2100. To accomplish this, humanity must reduce its carbon intensity—the amount of CO&l...Our Fair Plan to Safeguard Earth’s Climate reduces the emission of greenhouse gases to zero over the 80-year time period 2020 to 2100. To accomplish this, humanity must reduce its carbon intensity—the amount of CO<sub>2</sub> emitted per unit of energy—and its energy intensity—the amount of energy needed to generate a unit of Gross World Product. As shown in our Fair Plan 8 paper, reducing the future growth of the human population can also contribute to the reduction in greenhouse-gas emissions. Here, we explore this further. We project the historical decrease in Total Fertility Rate (TFR) across the 21<sup>st</sup> century toward its logistical asymptotic Reference value of 2.04 Births Per Woman (BPW). We then engineer the asymptotic TFR beginning in 2020 to 1.95, 1.85, 1.75, 1.65 & 1.55 BPW. We project the population across the 21<sup>st</sup> century for the Reference and engineered TFRs. We do so using the results of Basten, Lutz and Scherbov (2013) for the population evolution across the 21<sup>st</sup> century for 8 constant TFR values (=2.50, 2.25, 2.00, 1.75, 1.50, 1.25, 1.00 & 0.75 BPW). We find that purposefully engineering the asymptotic TFR can significantly contribute to achieving the reduction in greenhouse-gas emissions needed to transition to our Fair Plan to Safeguard Earth’s Climate.展开更多
The clinical applications of acrosin activity are limited.We analyzed 61578 male partners in infertile couples who visited the outpatient department of the Reproductive and Genetic Hospital of CITIC-Xiangya(Changsha,C...The clinical applications of acrosin activity are limited.We analyzed 61578 male partners in infertile couples who visited the outpatient department of the Reproductive and Genetic Hospital of CITIC-Xiangya(Changsha,China)between August 2014 and December 2019 to determine the reference ranges and thresholds for acrosin activity in infertile Chinese men;to determine whether correlations exist between acrosin activity and age,sperm concentration,sperm morphology,or sperm motility;and to evaluate whether acrosin activity could serve as an effective prognostic indicator for choosing between in vitro fertilization(IvF)and intracytoplasmic sperm injection(icsl)in the clinic.The cut-off value for the normal reference range of acrosin activity for male partners in infertile couples was 24.78μlU per 106 sperm.There was no significant association between acrosin activity and age,sperm concentration,semen volume,total sperm count,progressive motility,or total motile spermatozoa.A weak positive correlation was found between acrosin activity and normal sperm morphology.There was a statistically significant difference in abnormal acrosome morphology between the group with high acrosin activity(>24.78μlU per 106 sperm)and the group with low acrosin activity(<24.78μlU per 106 sperm).The group with a low IVF fertilization rate had a high index of abnormal acrosomal morphology at 21.2%,while the group with a high IVF fertilization rate had a low index of 0.2%.At an acrosin activity of<24.78μlU per 10 sperm,in one cycle of the same patient,the fertilization rate,normal fertilization rate,and good-quality embryo rate for Icsl were significantly higher than those for IVF.Therefore,the most promising application of acrosin activity could be in the selection of IcsI over IVF for infertile male patients with complete fertilization failure or a low fertilization rate.展开更多
Background Kernza®intermediate wheatgrass is a perennial grain and forage crop that can provide several ecosystem services.Major research efforts focused on Kernza have taken place in high latitudes.The goal of t...Background Kernza®intermediate wheatgrass is a perennial grain and forage crop that can provide several ecosystem services.Major research efforts focused on Kernza have taken place in high latitudes.The goal of this study was to evaluate,for the first time,the agronomic performance of Kernza in a low-latitude region with mild winters.Methods A KS-cycle 4 Kernza population(A)was planted in spring in Wisconsin,USA,and selected in one cycle for lower vernalization requirements,obtaining a new population(B).These two populations,at three nitrogen(N)fertilization rates,were evaluated in a full factorial,completely randomized field experiment in Uruguay over 2 years.Results The populations were similar in grain yields and flowering time in the 1st year,but population B had 63%lower grain yield in the 2nd year and 20%lower forage yield throughout the experiment.Increasing the N rate to 160 kg ha−1 led to a 63%increase in grain yield and 28%increase in forage yield across populations.Forage yields and nutritive values were similar to those reported in the northern hemisphere.However,grain yields for both the 1st(316 kg ha−1)and 2nd year(41 kg ha−1)were lower due to reduced flowering and weed competition.Conclusions Expansion of Kernza to lower-latitude regions will require further breeding to improve reproductive performance.展开更多
The present study aimed to evaluate the clinical outcomes of magnetic-activated cell sorting(MACS)in sperm preparation for male subjects with a sperm DNA fragmentation index(DFI)≥30%.A total of 86 patients who had un...The present study aimed to evaluate the clinical outcomes of magnetic-activated cell sorting(MACS)in sperm preparation for male subjects with a sperm DNA fragmentation index(DFI)≥30%.A total of 86 patients who had undergone their first long-term long protocol were selected.The protocol involved in vitro fertilization(IVF)and intracytoplasmic sperm injection(ICSI)cycles,and the patients were divided into the MACS or control groups.The MACS group included sperm samples analyzed with MACS that were combined with density gradient centrifugation(DGC)and the swim-up(SU)technique(n=39),and the control group included sperm samples prepared using standard techniques(DGC and SU;n=41).No differences were noted with regard to basic clinical characteristics,number of oocytes retrieved,normal fertilization rate,cleavage rate,or transplantable embryo rate between the two groups in IVF/ICSI.In addition,the clinical pregnancy and implantation rates of the first embryo transfer cycles indicated no significant differences between the two groups.However,there was a tendency to improve the live birth rate(LBR)of the first embryo transfer cycle(63.2%vs 53.9%)and the cumulative LBR(79.5%vs 70.7%)in the MACS group compared with the control group.Moreover,the number of transferred embryos(mean±standard deviation[s.d.]:1.7±0.7 vs 2.3±1.6)and the transfer number of each retrieved cycle(mean±s.d.:1.2±0.5 vs 1.6±0.8)were significantly lower in the MACS group than those in the control group.Thus,the selection of nonapoptotic spermatozoa by MACS for higher sperm DFI could improve assisted reproductive clinical outcomes.展开更多
Orchard target-oriented fertilizing with on-board sensor technology can improve fertilizer efficiency and reduce environmental pollution.Photoelectric sensors are widely used for object detection because of their low ...Orchard target-oriented fertilizing with on-board sensor technology can improve fertilizer efficiency and reduce environmental pollution.Photoelectric sensors are widely used for object detection because of their low cost and fast response time.This paper presents a Wolfberry tree dual-model detection method and the design of an orchard target-oriented variable-rate fertilization system based on photoelectric sensors.The dual-model detection method includes the Trunk Detection Model(TDM)and Canopy Detection Model(CDM),which can be applied for Wolfberry orchards at the green cluster and mature stages,respectively.A target-oriented fertilization system was designed using the dual-model method,and tested in the lab and Chinese Wolfberry orchard.The laboratory test results showed that the average center offset distances on the condition of detecting trunks,continuous canopies,and discontinuous canopies were 4.1 cm,9.1 cm and 13.1 cm,respectively.The system could ignore the signals from canes when their diameters were less than 16 mm,and also could determine the gaps within a tree when they were less than 21 cm.The orchard test results showed that the system accomplished target-oriented fertilization 95 times for 92 trees at the mature stage.The results indicated that the dual-model detection method could be used for Wolfberry trees or other trees with similar canopy changes at different growth stages.展开更多
A child is born to a father and a mother.This fact,however,is yet to be recognized by demography,in which fertility refers to women’s natural ability to give birth.The main reason for the absence of men is that data ...A child is born to a father and a mother.This fact,however,is yet to be recognized by demography,in which fertility refers to women’s natural ability to give birth.The main reason for the absence of men is that data on births are more often available for women than for men.But in the last few decades,data availability has greatly improved.Recent studies show that total fertility rates(TFRs)of men can be calculated for most countries in the world and that the difference between the TFRs of men and women can be quite large.For low-fertility countries,nonetheless,these studies show little difference between the TFRs of men and women,giving rise to the question:Is men’s fertility worth further investigation?To avoid ambiguity in describing a particular difference as small or big,this paper provides a formula for probabilistic TFRs.Using hypothesis test on probabilistic TFRs,we can say that the difference between the TFRs of men and women is statistically significant for all the G7 countries,except for France.To explain the differences between the TFRs of men and women,this study uses models of stable populations and concludes that the one-sex stable population models cannot explain the results whereas a two-sex joint stable population model can do so.By using the two-sex population model,we can explain why the TFR of men in France is almost the same as that of women,and why it is lower than that of women in the other six G7 countries.More specifically,by using the model,we can help explain 76%of the variance in the difference between the TFRs of men and women.Future studies may be able to show that men’s TFR is significantly lower than women’s in other countries too and explain why it is so.The above findings,however,require closer attention and further investigation,because low fertility could lead to socioeconomic problems.Beyond TFRs,extending fertility studies from women to men as well,that is,conducting fertility studies on both women and men,will fundamentally improve our knowledge about fertility age patterns,trends,determinants,policies and other related issues.展开更多
This paper studied the fertilizer rate(FR), fertilizer use efficiency(FUE) and fertilizer overuse rate(FOR) of rice, corn and wheat in China from 1998 to 2018 and briefly analysed the reasons why farmers were willing ...This paper studied the fertilizer rate(FR), fertilizer use efficiency(FUE) and fertilizer overuse rate(FOR) of rice, corn and wheat in China from 1998 to 2018 and briefly analysed the reasons why farmers were willing to apply more fertilizers.(1) The FR of grain in China reached 373.7 kg/ha in 2018, an increase of 26.8% compared to that in 1998. In 2018, the FR for corn was the highest, at 411.2 kg/ha, compared to the values of 338.3 kg/ha for rice and 371.7 kg/ha for wheat.(2) In recent years, the FUE of grain in China has obviously improved, with values of 32.9% in 1998, 36.7% in 2008, and 39.3% in 2018. In 2018, the FUE for rice was the highest(41.2%), followed by that for corn(39.9%), and the FUE for wheat was the lowest(36.0%).(3) By 2018, fertilizer was overused in all zones of rice, corn and wheat. In 2018, the average FOR for wheat reached 69.0%, which was 35.9% higher than that for corn and 42.8% higher than that for rice.(4) The lower price of chemical fertilizers was the main reason leading to overapplication.(5) Establishing market mechanisms and adjusting regional planting structures can be effective in reducing the application of chemical fertilizers.展开更多
Based on China fertility survey 2017,this report presents the national fertility level,age-specific fertility rate and parity distribution.The survey results show that during 2006-2016 the mean ages at first marriage ...Based on China fertility survey 2017,this report presents the national fertility level,age-specific fertility rate and parity distribution.The survey results show that during 2006-2016 the mean ages at first marriage and first birth increased by 2.7 and 2.6 years respectively.From 2006 to 2011,the total fertility rate was around 1.60-1.70,and experienced notable fluctuations during 2012-2016.Compared the age-specific fertility in 2006 with in 2011,the curve in 2016 shifted significantly to the right side.Affected by the relaxation of the fertility policy,the proportion of second births among the total births had increased year by year since 2012.展开更多
It is the need of time that oil palm farmers must perform the spatially planned soil analysis to know about the fertilizer sufficient and deficient zones of land.Colorimetric method is a suitable and fast solution of ...It is the need of time that oil palm farmers must perform the spatially planned soil analysis to know about the fertilizer sufficient and deficient zones of land.Colorimetric method is a suitable and fast solution of soil analysis for NPK determination using the digital soil test kit.NPK determination procedure with a digital soil test kit was undefined for oil palm.Furthermore,the digital soil test kit determines the passage of light through an opaque medium of soil solution with a specified reagent.Therefore,environmental light may interfere leading to wrong results of NPK measurement.Likewise,this equipment was non-incorporable with the controller of any VRT fertilizer applicator.In this research,these issues were addressed and the NPK measurement procedure was defined for oil palm plantation by modifying the‘soil to water’ratio in sample soil solution with an optimum environmental light range of 18-23 W/m^(2).‘Soil to water’ratios were found for nitrogen,phosphorus and potassium as 0.31 to 5.00,1.00 to 5.00 and 4.50 to 5.00,respectively to fit the requirement of NPK for oil palm in the prescribed range of the equipment.Validation study of modified digital soil test kit showed that 91.7%N,89.6%P and 93.8%K results of modified digital soil test kit were matched with analytical laboratory method.Thus,the reliability of NPK results using digital soil test kit was enhanced,making the kit incorporable with the controller of variable rate fertilizer applicator through remote monitoring based data acquisition system.The outcome of this research can be used in the development of an IoT network data fusion for dynamic assessment of the NPK variation in the soil and nutrient management in oil palm plantations.展开更多
China’s“one-child policy”that had been in force between 1980 and 2016 evolved over time and differed widely between regions.Local policies in many regions also targeted the timing and spacing of childbearing by set...China’s“one-child policy”that had been in force between 1980 and 2016 evolved over time and differed widely between regions.Local policies in many regions also targeted the timing and spacing of childbearing by setting the minimum age at mar-riage,first birth and second birth and defining minimum interval between births.Our study uses data from the 120 Counties Population Dynamics Monitoring Sys-tem to reconstruct fertility level and timing in nine counties in Shandong province,which experienced frequent changes in birth and marriage policies.We reconstruct detailed indicators of fertility by birth order in 1986-2016,when policies on mar-riage and fertility timing became strictly enforced since 1989 and subsequently relaxed(especially in 2002)and abandoned(in 2013).Our analysis reveals that birth timing policies have fuelled drastic changes in fertility level,timing and spacing in the province.In the early 1990s period fertility rates plummeted to extreme low levels,with the provincial average total fertility rate falling below 1 in 1992-1995.Second births rates fell especially sharply.The age schedule of childbearing shifted to later ages and births became strongly concentrated just above the minimum pol-icy age at first and second birth,resulting in a bimodal distribution of fertility with peaks at ages 25 and 32.Conversely,the abandonment of the province-level policy on the minimum age at marriage and first birth and less strict enforcement of the policy on the minimum age at second birth contributed to a recovery of period fertil-ity rates in the 2000s and a shift to earlier timing of first and second births.It also led to a shorter second birth interval and a re-emergence of a regular age schedule of fertility with a single peak around age 28.展开更多
Exploring the patterns of population change under low fertility is a historical mission for demographic research in the 21st century.Taking Shanghai as an example,this paper discusses the new patterns and charac...Exploring the patterns of population change under low fertility is a historical mission for demographic research in the 21st century.Taking Shanghai as an example,this paper discusses the new patterns and characteristics of people’s childbearing intention and behavior under low fertility settings.The results show that Shanghai,as a typical society with ultra-low fertility,people’s childbearing intention and behavior demonstrate the characteristics such as“downward inconsistency”between childbearing intention and childbearing behavior,“convergence”of childbearing intention and childbearing behavior between different sub-groups,“inversion”in childbearing intention and childbearing behavior with education and income,and the“decoupling”between marriage and childbearing.The childbearing intention and behavior of low fertility society as seen in the case of Shanghai show the patterns as somehow different from what was observed in a high fertility society.It suggests that many of the childbearing patterns shown in the high-fertility era may not necessarily be applicable in low fertility settings,and urges more research to be carried out in this regard.展开更多
Recent drastic changes in marriage and fertility behaviour have a considerable impact on China’s annual number of births.Population momentum and changing fertility policy largely determine the changing number of birt...Recent drastic changes in marriage and fertility behaviour have a considerable impact on China’s annual number of births.Population momentum and changing fertility policy largely determine the changing number of births in China over the past two decades.While the annual number of births have been steadily fluctuat-ing around 16-18 million,contrary trends in the number of the first births and the second births have been observed.The two-child policy produced marked effects on the rising number of the second births,which is however to a large extent offset by the declining number of the first births resulting from rapidly postponing age at first marriage.A decomposition analysis demonstrates that all demographic factors are depressing birth numbers,including the size of reproductive-age women and its age structure,proportion married and marital fertility in the very recent years.China’s seventh population census conducted in 2020 suggests a more rapid decline in birth numbers,marking the start of a lowest-low fertility in Chinese history.展开更多
文摘Fertility policies consist of not only the legal definition of"procreation",but also the"maternity"protection system,the complete set of selfconsistent social relations and policy systems formed around"fertility".Gender,labor and intergenerational relations are the cornerstones of a fertility policy system.In this framework,we focus on women of childbearing age as the main actors of reproductive behaviors,to research how drastic social changes have altered women,the above-mentioned relations,and policy support and analyze the structural factors that restrict women’s reproductive intentions.The traditional male breadwinner model,which can no longer prevail and the relatively slow development of maternity protection policies and service systems leave women of childbearing age in a dilemma between working hours and birth timing.Therefore,maternity protection policies should focus on improved decommodification of maternity insurance and the construction of women and children’s social welfare systems including childcare social service systems.
文摘Gender discrimination has long been the problem that exists in the entire world,including China.However,as more and more people are focusing on the general gender discrimination,the group recognized an extension of such discrimination-pregnancy discrimination in job hiring(the discrimination that women who are pregnant or have the inclination to pregnancy receive in hiring).The possible subtle pregnancy discrimination may be one of the main causes that lead to the declining fertility rate in China.The group decided to conduct an experiment to determine whether women are receiving more subtle discrimination in job hiring due to their identity as mother than men with children,men without children,and women without children.Using the form of questionary and resumes,the team found that Chinese women are indeed enduring subtle discrimination in work hiring.The experiment highlights the importance to promote further equality among women.However,there are some confounding variables,like the level of patient of the HR who reads the resume,affecting the ultimate result of the study.Keywords:gender discrimination,women’s career,Chinese job market,pregnancy discrimination,fertility rate in China.
基金We acknowledge that the research is supported by the National Key Technology Research and Development Program(No.2012BAK17B15).
文摘This paper presented a novel variable rate fertilization system based on the method of adjusting the active feed-roll length of a fluted roller.The feasibility of this method was discussed using analysis of the fluted roller model.One seed drill produced by Kuhn Company(France),which could sow and fertilize simultaneously,was used as a test platform to implement the mechanical structure of variable rate fertilization.The design methods for the variable rate fertilization mechanical structure and actuator were introduced in detail.A low-cost and stable embedded support decision subsystem and corresponding software were developed.The support decision subsystem is based on grid management.Each grid field cell contains information about corresponding spatial position and fertilizer application rate.A SpatiaLite database was employed to solve the spatial location search and spatial data query.Experiments were conducted to evaluate the fertilization uniformity and dynamic response time.The average value of coefficient of variation is 8.4%in five different active feed-roll lengths which reflects good uniformity.The dynamic response times for the adjustment of variable rate fertilization system from 204 kg/hm^(2) to 319 kg/hm^(2) and 319 kg/hm^(2) to 204 kg/hm^(2) are about 4.2 s.The results suggest that the variable rate fertilization system performs well in dynamic adjustment and stability.
基金The authors express appreciation for the financial support provided by National Key Technologies R&D Program of China(No.2017YFD0700305 and No.2016YFD0200600-2016YFD0200602-4)Fundamental Research Funds for Central Non-profit Scientific Institution(S201712).
文摘The key technical problem of variable rate fertilization system based on spectrum information was precise variable fertilization in certain area according to the acquired spectrum information.Hysteretic fertilizing is a critical problem in most of current fertilizer equipment.Hysteresis model was built and analyzed in this study to improve the system.Fertilizing tests were conducted on different wheat breeds and the results were analyzed.The tests showed that variable rate fertilization had obvious hysteresis phenomenon with the maximum lag distance of 3.82 m,the minimum lag distance of 1.73 m and average of 3.06 m.Hysteresis phenomenon of the variable rate fertilization system was obviously decreased when implanting a correction time of 2.04 s with the maximum lag distance of 0.61 m.Variable effects varied by different wheat breeds.Variable rate fertilization had an advantage of improving spatial differences of Yangmai-23,and the spatial variability of which decreased by 14.23%.In the small test area,the amount of fertilizer in Zhenmai-168 decreased by 2.84 kg,while the amount of which in Yangmai-23 increased by 3.83 kg.Yield of Zhenmai-168 in small area was lower than that in traditional pattern,but the condition of Yangmai-23 was on the contrary.Valuable information for increasing performance of fertilization in variable rate fertilization system was provided in this paper.
基金The authors acknowledge that this work was financially supported by the National Natural Science Foundation of China(No.31401284)the National Key Technology Research and Development Program of the Ministry of Science and Technology of China(No.2014BAD06B03).
文摘In order to improve soil fertility and fertilizer utilization,a subsoiling variable rate fertilization machine based on conservation tillage and precision agriculture was designed and tested.The relationship between suspension parameters and penetrating distance was analyzed,and a matching model between fertilizing quantity and penetrating distance was established.The variable rate fertilization control machine was developed based on an Advantech PCM-9363 industrial control mainboard.The machine operates under two patterns:DGPS-based positioning and straight-line path positioning based on a planar coordinate system.This machine can perform on-demand fertilization according to the spatial differences in soil nutrients and the prescription maps pre-set before the operation.Field experiments showed the machine has a subsoiling stability of 92.5%,a soil breaking rate of 61.1%,a maximum positioning relative error of 2.68%and a maximum variable rate fertilization error of 3.89%.The subsoiling performance and variable rate fertilization indices of this machine satisfy the requirements of GB/T24675.2-2009.The tested indices meet the national and industrial standards and satisfy the design requirements.The findings of the research can be used as the structural design of the subsoiling variable rate fertilization machine.
文摘This paper first described the current status of wheat nitrogen fertilizers utilization rate. Then,from balanced fertilizer application,applying slow/controlled release fertilizer,deep application of nitrogen fertilizers and graded application,controlled application amount,selection of application time according to soil properties,diagnosed application of fertilizer with instrument,addition of synergist,and precise fertilizer application,it summarized biological nitrogen saving methods and introduced prospects of future biological nitrogen saving technology.
文摘Our Fair Plan to Safeguard Earth’s Climate reduces the emission of greenhouse gases to zero over the 80-year time period 2020 to 2100. To accomplish this, humanity must reduce its carbon intensity—the amount of CO<sub>2</sub> emitted per unit of energy—and its energy intensity—the amount of energy needed to generate a unit of Gross World Product. As shown in our Fair Plan 8 paper, reducing the future growth of the human population can also contribute to the reduction in greenhouse-gas emissions. Here, we explore this further. We project the historical decrease in Total Fertility Rate (TFR) across the 21<sup>st</sup> century toward its logistical asymptotic Reference value of 2.04 Births Per Woman (BPW). We then engineer the asymptotic TFR beginning in 2020 to 1.95, 1.85, 1.75, 1.65 & 1.55 BPW. We project the population across the 21<sup>st</sup> century for the Reference and engineered TFRs. We do so using the results of Basten, Lutz and Scherbov (2013) for the population evolution across the 21<sup>st</sup> century for 8 constant TFR values (=2.50, 2.25, 2.00, 1.75, 1.50, 1.25, 1.00 & 0.75 BPW). We find that purposefully engineering the asymptotic TFR can significantly contribute to achieving the reduction in greenhouse-gas emissions needed to transition to our Fair Plan to Safeguard Earth’s Climate.
基金This study was supported by the Hunan Province Municipal Natural Science Foundation(2022JJ30018)to WNLHunan Province Health Commission Science Foundation(B202301037899)to WNLResearch Grant of CITIC-Xiangya(YNXM-201904)to WNL.
文摘The clinical applications of acrosin activity are limited.We analyzed 61578 male partners in infertile couples who visited the outpatient department of the Reproductive and Genetic Hospital of CITIC-Xiangya(Changsha,China)between August 2014 and December 2019 to determine the reference ranges and thresholds for acrosin activity in infertile Chinese men;to determine whether correlations exist between acrosin activity and age,sperm concentration,sperm morphology,or sperm motility;and to evaluate whether acrosin activity could serve as an effective prognostic indicator for choosing between in vitro fertilization(IvF)and intracytoplasmic sperm injection(icsl)in the clinic.The cut-off value for the normal reference range of acrosin activity for male partners in infertile couples was 24.78μlU per 106 sperm.There was no significant association between acrosin activity and age,sperm concentration,semen volume,total sperm count,progressive motility,or total motile spermatozoa.A weak positive correlation was found between acrosin activity and normal sperm morphology.There was a statistically significant difference in abnormal acrosome morphology between the group with high acrosin activity(>24.78μlU per 106 sperm)and the group with low acrosin activity(<24.78μlU per 106 sperm).The group with a low IVF fertilization rate had a high index of abnormal acrosomal morphology at 21.2%,while the group with a high IVF fertilization rate had a low index of 0.2%.At an acrosin activity of<24.78μlU per 10 sperm,in one cycle of the same patient,the fertilization rate,normal fertilization rate,and good-quality embryo rate for Icsl were significantly higher than those for IVF.Therefore,the most promising application of acrosin activity could be in the selection of IcsI over IVF for infertile male patients with complete fertilization failure or a low fertilization rate.
基金This research was funded by competitive grants from Fondo María Viñas of ANII(Agencia Nacional de Investigación e Innovación,Uruguay)to A.L.,and full-time funds(DT,UDELAR,Uruguay)granted to A.L.
文摘Background Kernza®intermediate wheatgrass is a perennial grain and forage crop that can provide several ecosystem services.Major research efforts focused on Kernza have taken place in high latitudes.The goal of this study was to evaluate,for the first time,the agronomic performance of Kernza in a low-latitude region with mild winters.Methods A KS-cycle 4 Kernza population(A)was planted in spring in Wisconsin,USA,and selected in one cycle for lower vernalization requirements,obtaining a new population(B).These two populations,at three nitrogen(N)fertilization rates,were evaluated in a full factorial,completely randomized field experiment in Uruguay over 2 years.Results The populations were similar in grain yields and flowering time in the 1st year,but population B had 63%lower grain yield in the 2nd year and 20%lower forage yield throughout the experiment.Increasing the N rate to 160 kg ha−1 led to a 63%increase in grain yield and 28%increase in forage yield across populations.Forage yields and nutritive values were similar to those reported in the northern hemisphere.However,grain yields for both the 1st(316 kg ha−1)and 2nd year(41 kg ha−1)were lower due to reduced flowering and weed competition.Conclusions Expansion of Kernza to lower-latitude regions will require further breeding to improve reproductive performance.
基金supported by the National Natural Science Foundation of China(No.81801518 and No.82071646).
文摘The present study aimed to evaluate the clinical outcomes of magnetic-activated cell sorting(MACS)in sperm preparation for male subjects with a sperm DNA fragmentation index(DFI)≥30%.A total of 86 patients who had undergone their first long-term long protocol were selected.The protocol involved in vitro fertilization(IVF)and intracytoplasmic sperm injection(ICSI)cycles,and the patients were divided into the MACS or control groups.The MACS group included sperm samples analyzed with MACS that were combined with density gradient centrifugation(DGC)and the swim-up(SU)technique(n=39),and the control group included sperm samples prepared using standard techniques(DGC and SU;n=41).No differences were noted with regard to basic clinical characteristics,number of oocytes retrieved,normal fertilization rate,cleavage rate,or transplantable embryo rate between the two groups in IVF/ICSI.In addition,the clinical pregnancy and implantation rates of the first embryo transfer cycles indicated no significant differences between the two groups.However,there was a tendency to improve the live birth rate(LBR)of the first embryo transfer cycle(63.2%vs 53.9%)and the cumulative LBR(79.5%vs 70.7%)in the MACS group compared with the control group.Moreover,the number of transferred embryos(mean±standard deviation[s.d.]:1.7±0.7 vs 2.3±1.6)and the transfer number of each retrieved cycle(mean±s.d.:1.2±0.5 vs 1.6±0.8)were significantly lower in the MACS group than those in the control group.Thus,the selection of nonapoptotic spermatozoa by MACS for higher sperm DFI could improve assisted reproductive clinical outcomes.
基金This work was supported by Shaanxi Science and Technology Projects(2017KJXX-54 and 2014KTCL02-15)Science and Technology Project of Northwest A&F University(Z222021560)the"Young Faculty Study Abroad Program"of Northwest A&F University Scholarship Fund.
文摘Orchard target-oriented fertilizing with on-board sensor technology can improve fertilizer efficiency and reduce environmental pollution.Photoelectric sensors are widely used for object detection because of their low cost and fast response time.This paper presents a Wolfberry tree dual-model detection method and the design of an orchard target-oriented variable-rate fertilization system based on photoelectric sensors.The dual-model detection method includes the Trunk Detection Model(TDM)and Canopy Detection Model(CDM),which can be applied for Wolfberry orchards at the green cluster and mature stages,respectively.A target-oriented fertilization system was designed using the dual-model method,and tested in the lab and Chinese Wolfberry orchard.The laboratory test results showed that the average center offset distances on the condition of detecting trunks,continuous canopies,and discontinuous canopies were 4.1 cm,9.1 cm and 13.1 cm,respectively.The system could ignore the signals from canes when their diameters were less than 16 mm,and also could determine the gaps within a tree when they were less than 21 cm.The orchard test results showed that the system accomplished target-oriented fertilization 95 times for 92 trees at the mature stage.The results indicated that the dual-model detection method could be used for Wolfberry trees or other trees with similar canopy changes at different growth stages.
文摘A child is born to a father and a mother.This fact,however,is yet to be recognized by demography,in which fertility refers to women’s natural ability to give birth.The main reason for the absence of men is that data on births are more often available for women than for men.But in the last few decades,data availability has greatly improved.Recent studies show that total fertility rates(TFRs)of men can be calculated for most countries in the world and that the difference between the TFRs of men and women can be quite large.For low-fertility countries,nonetheless,these studies show little difference between the TFRs of men and women,giving rise to the question:Is men’s fertility worth further investigation?To avoid ambiguity in describing a particular difference as small or big,this paper provides a formula for probabilistic TFRs.Using hypothesis test on probabilistic TFRs,we can say that the difference between the TFRs of men and women is statistically significant for all the G7 countries,except for France.To explain the differences between the TFRs of men and women,this study uses models of stable populations and concludes that the one-sex stable population models cannot explain the results whereas a two-sex joint stable population model can do so.By using the two-sex population model,we can explain why the TFR of men in France is almost the same as that of women,and why it is lower than that of women in the other six G7 countries.More specifically,by using the model,we can help explain 76%of the variance in the difference between the TFRs of men and women.Future studies may be able to show that men’s TFR is significantly lower than women’s in other countries too and explain why it is so.The above findings,however,require closer attention and further investigation,because low fertility could lead to socioeconomic problems.Beyond TFRs,extending fertility studies from women to men as well,that is,conducting fertility studies on both women and men,will fundamentally improve our knowledge about fertility age patterns,trends,determinants,policies and other related issues.
基金The Second Tibetan Plateau Scientific Expedition and Research Program,No.2019QZKK0603Strategic Priority Research Program of Chinese Academy of Sciences,No.XDA20040000,No.XDA20090000。
文摘This paper studied the fertilizer rate(FR), fertilizer use efficiency(FUE) and fertilizer overuse rate(FOR) of rice, corn and wheat in China from 1998 to 2018 and briefly analysed the reasons why farmers were willing to apply more fertilizers.(1) The FR of grain in China reached 373.7 kg/ha in 2018, an increase of 26.8% compared to that in 1998. In 2018, the FR for corn was the highest, at 411.2 kg/ha, compared to the values of 338.3 kg/ha for rice and 371.7 kg/ha for wheat.(2) In recent years, the FUE of grain in China has obviously improved, with values of 32.9% in 1998, 36.7% in 2008, and 39.3% in 2018. In 2018, the FUE for rice was the highest(41.2%), followed by that for corn(39.9%), and the FUE for wheat was the lowest(36.0%).(3) By 2018, fertilizer was overused in all zones of rice, corn and wheat. In 2018, the average FOR for wheat reached 69.0%, which was 35.9% higher than that for corn and 42.8% higher than that for rice.(4) The lower price of chemical fertilizers was the main reason leading to overapplication.(5) Establishing market mechanisms and adjusting regional planting structures can be effective in reducing the application of chemical fertilizers.
文摘Based on China fertility survey 2017,this report presents the national fertility level,age-specific fertility rate and parity distribution.The survey results show that during 2006-2016 the mean ages at first marriage and first birth increased by 2.7 and 2.6 years respectively.From 2006 to 2011,the total fertility rate was around 1.60-1.70,and experienced notable fluctuations during 2012-2016.Compared the age-specific fertility in 2006 with in 2011,the curve in 2016 shifted significantly to the right side.Affected by the relaxation of the fertility policy,the proportion of second births among the total births had increased year by year since 2012.
基金This research was supported by Universiti Putra Malaysia in coordination of United Melaka Bhd.(UMB).
文摘It is the need of time that oil palm farmers must perform the spatially planned soil analysis to know about the fertilizer sufficient and deficient zones of land.Colorimetric method is a suitable and fast solution of soil analysis for NPK determination using the digital soil test kit.NPK determination procedure with a digital soil test kit was undefined for oil palm.Furthermore,the digital soil test kit determines the passage of light through an opaque medium of soil solution with a specified reagent.Therefore,environmental light may interfere leading to wrong results of NPK measurement.Likewise,this equipment was non-incorporable with the controller of any VRT fertilizer applicator.In this research,these issues were addressed and the NPK measurement procedure was defined for oil palm plantation by modifying the‘soil to water’ratio in sample soil solution with an optimum environmental light range of 18-23 W/m^(2).‘Soil to water’ratios were found for nitrogen,phosphorus and potassium as 0.31 to 5.00,1.00 to 5.00 and 4.50 to 5.00,respectively to fit the requirement of NPK for oil palm in the prescribed range of the equipment.Validation study of modified digital soil test kit showed that 91.7%N,89.6%P and 93.8%K results of modified digital soil test kit were matched with analytical laboratory method.Thus,the reliability of NPK results using digital soil test kit was enhanced,making the kit incorporable with the controller of variable rate fertilizer applicator through remote monitoring based data acquisition system.The outcome of this research can be used in the development of an IoT network data fusion for dynamic assessment of the NPK variation in the soil and nutrient management in oil palm plantations.
文摘China’s“one-child policy”that had been in force between 1980 and 2016 evolved over time and differed widely between regions.Local policies in many regions also targeted the timing and spacing of childbearing by setting the minimum age at mar-riage,first birth and second birth and defining minimum interval between births.Our study uses data from the 120 Counties Population Dynamics Monitoring Sys-tem to reconstruct fertility level and timing in nine counties in Shandong province,which experienced frequent changes in birth and marriage policies.We reconstruct detailed indicators of fertility by birth order in 1986-2016,when policies on mar-riage and fertility timing became strictly enforced since 1989 and subsequently relaxed(especially in 2002)and abandoned(in 2013).Our analysis reveals that birth timing policies have fuelled drastic changes in fertility level,timing and spacing in the province.In the early 1990s period fertility rates plummeted to extreme low levels,with the provincial average total fertility rate falling below 1 in 1992-1995.Second births rates fell especially sharply.The age schedule of childbearing shifted to later ages and births became strongly concentrated just above the minimum pol-icy age at first and second birth,resulting in a bimodal distribution of fertility with peaks at ages 25 and 32.Conversely,the abandonment of the province-level policy on the minimum age at marriage and first birth and less strict enforcement of the policy on the minimum age at second birth contributed to a recovery of period fertil-ity rates in the 2000s and a shift to earlier timing of first and second births.It also led to a shorter second birth interval and a re-emergence of a regular age schedule of fertility with a single peak around age 28.
基金supported by 2019 The National Social Sciences Fund of China(19CRK017):“Study on the new characteristics,causes,influences and trends of marriage behavior of residents in big cities of China”.
文摘Exploring the patterns of population change under low fertility is a historical mission for demographic research in the 21st century.Taking Shanghai as an example,this paper discusses the new patterns and characteristics of people’s childbearing intention and behavior under low fertility settings.The results show that Shanghai,as a typical society with ultra-low fertility,people’s childbearing intention and behavior demonstrate the characteristics such as“downward inconsistency”between childbearing intention and childbearing behavior,“convergence”of childbearing intention and childbearing behavior between different sub-groups,“inversion”in childbearing intention and childbearing behavior with education and income,and the“decoupling”between marriage and childbearing.The childbearing intention and behavior of low fertility society as seen in the case of Shanghai show the patterns as somehow different from what was observed in a high fertility society.It suggests that many of the childbearing patterns shown in the high-fertility era may not necessarily be applicable in low fertility settings,and urges more research to be carried out in this regard.
基金support by the Research Fund of Renmin University of China(Grant No.20XNL025).
文摘Recent drastic changes in marriage and fertility behaviour have a considerable impact on China’s annual number of births.Population momentum and changing fertility policy largely determine the changing number of births in China over the past two decades.While the annual number of births have been steadily fluctuat-ing around 16-18 million,contrary trends in the number of the first births and the second births have been observed.The two-child policy produced marked effects on the rising number of the second births,which is however to a large extent offset by the declining number of the first births resulting from rapidly postponing age at first marriage.A decomposition analysis demonstrates that all demographic factors are depressing birth numbers,including the size of reproductive-age women and its age structure,proportion married and marital fertility in the very recent years.China’s seventh population census conducted in 2020 suggests a more rapid decline in birth numbers,marking the start of a lowest-low fertility in Chinese history.
