Autonomous vehicle technology will transform fundamentally urban traffic systems.To better enhance the coming era of connected and autonomous vehicles,effective control strategies that interact wisely with these intel...Autonomous vehicle technology will transform fundamentally urban traffic systems.To better enhance the coming era of connected and autonomous vehicles,effective control strategies that interact wisely with these intelligent vehicles for signalized at-grade intersections are indispensable.Vehicle-to-infrastructure communication technology offers unprecedented clues to reduce the delay at signalized intersections by innovative information-based control strategies.This paper proposes a new dynamic control strategy for signalized intersections with vehicle-to-signal information.The proposed strategy is called periodic vehicle holding(PVH)strategy while the traffic signal can provide information for the vehicles that are approaching an intersection.Under preliminary autonomous vehicle(PAV)environment,left-turning and through-moving vehicles will be sorted based on different information they receive.The paper shows how PVH reorganizes traffic to increase the capacity of an intersection without causing severe spillback to the upstream intersection.Results show that PVH can reduce the delay by approximately 15%at a signalized intersection under relatively high traffic demand.展开更多
Combined with recent historical climate data and two periods of land use datasets from remote sensing data, we test the net primary productivity (NPP) data sets in North Chinamodelled by the satellite data-driven Glob...Combined with recent historical climate data and two periods of land use datasets from remote sensing data, we test the net primary productivity (NPP) data sets in North Chinamodelled by the satellite data-driven Global Production Efficiency Model (GLO-PEM) for detecting thewidespread spatial and temporal characteristics of the impacts of climate and land use change onthe regional NPP. Our results show that over the past 20 years, the mean annual temperature in thestudy region has remarkably increased by more than 0.064 ℃, but over the same period, there hasbeen a 1.49 mm decrease in annual precipitation and decrease in NPP by an annual rate of 6.9 TgC.The NPP changes in the study region were greatly affected by the average temperature andprecipitation by ten-day periods as well as the seasonal temperature and precipitation in the studyregion. The correlation between seasonal NPP and seasonal precipitation and temperature is highlyconsistent with land cover spatially, and the correlation coefficient changes with the changes ofvegetation types. The analysis reveals that the related areas in land use change only take up 5.45%of the whole studied region, so the climate changes dominate the impacts on the NPP in the wholestudy region (90% of the total). However, land use plays an absolute dominative role in areas withland cover changes, accounting for 97% of the total. From 1981 to 2000, the NPP in the whole studyregion remarkably reduced due to obvious precipitation decrease and temperature rise. Between twoperiods of land use (about 10 years), the changes in climate are predicted to promote a decrease inNPP by 78 ( + -0.6) TgC, and integrated impacts of climate changes and land use to promote adecrease in NPP by 87(+-0.8) TgC.展开更多
AIM:Many defense factors of the mother's colostrum or milk protect infants from intestinal, respiratory and systemic infections. In the present study, we investigated the effect of colostrum and mature human milk ...AIM:Many defense factors of the mother's colostrum or milk protect infants from intestinal, respiratory and systemic infections. In the present study, we investigated the effect of colostrum and mature human milk on E. histolytica parasites in vitro.METHODS:Samples of human milk were collected from 5 healthy lactating mothers.The medium with human milk at concentrations of 2%, 5% and 10% was obtained.RESULTS:The lethal effect of E. histolytica on the medium supplemented with different concentrations of both colostrum and mature human milk was significant during the first 30min. We also detected that the results of colostrum and mature human milk were similar. No statistically significant differences were found between same concentrations of colostrum and mature human milk at the same times.CONCLUSION:Colostrum and mature human milk have significant lethal effect on E. histolytica and protect against its infection in breast fed children.展开更多
AIM:To explore the DNA image cytometry (DNA-ICM) technique as a primary screening method for esopha-geal squamous precancerous lesions.METHODS:This study was designed as a population-based screening study.A total of 5...AIM:To explore the DNA image cytometry (DNA-ICM) technique as a primary screening method for esopha-geal squamous precancerous lesions.METHODS:This study was designed as a population-based screening study.A total of 582 local residents aged 40 years-69 years were recruited from Linzhou in Henan and Feicheng in Shandong.However,only 452 subjects had results of liquid-based cytology,DNA-ICM and pathology.The sensitivity and specificity of DNA-ICM were calculated and compared with liquid-based cytology in moderate dysplasia or worse.RESULTS:Sensitivities of DNA-ICM ranging from at least 1 to 4 aneuploid cells were 90.91%,86.36%,79.55% and 77.27%,respectively,which were better than that of liquid-based cytology (75%).Specifici-ties of DNA-ICM were 70.83%,84.07%,92.65% and 96.81%,but the specificity of liquid-based cytology was 91.91%.The sensitivity and specificity of a combination of liquid-based cytology and DNA-ICM were 84.09% and 85.78%,respectively.CONCLUSION:It is possible to use DNA-ICM tech-nique as a primary screening method for esophageal squamous precancerous lesions.展开更多
Objectives:Effective and efficient communication is a core element in healthcare systems,especially between healthcare providers and patients.This study aimed to identify communication barriers be-tween nurses and pat...Objectives:Effective and efficient communication is a core element in healthcare systems,especially between healthcare providers and patients.This study aimed to identify communication barriers be-tween nurses and patients in primary healthcare centers in Bahrain.Methods:This is a cross-sectional study conducted across primary healthcare centers in Bahrain.Four hundred and two patients were recruited using convenience sampling.A self-administered question-naire comprising 29 items on communication barriers was used.Results:A total of 402 patients consented to participate.The majority of participants reported the following statements had large effects on communication:“shortage in the number of nurses compared to the large number of patients”(254/401,63.3%),“lack of desire of nurse to communicate with patients”(246/402,61.2%),and“negative attitude of the nurse toward the patient”(238/401,59.4%).Further,“difference in language between nurses and patients,”“lack of self-confidence by nurses,”and“nurses overwhelmed by work”were ranked as top three statements with a significant influence on commu-nication between nurses and patients.Conclusions:Communication between healthcare providers and patients is pivotal for an optimal healthcare service.Based on the findings of this study and the literature,we recommend formal training of health care workers in improving communication skills and including this not only in medical cur-riculum but also in the form of continuing medical education(CMEs)1.展开更多
Net primary productivity(NPP), a metric used to define and identify changes in plant communities, is greatly affected by climate change, human activities and other factors. Here, we used the Carnegie-Ames-Stanford App...Net primary productivity(NPP), a metric used to define and identify changes in plant communities, is greatly affected by climate change, human activities and other factors. Here, we used the Carnegie-Ames-Stanford Approach(CASA) model to estimate the NPP of plant communities in Hengduan Mountains area of China, and to explore the relationship between NPP and altitude in this region. We examined the mechanisms underlying vegetation growth responses to climate change and quantitatively assessed the effects of ecological protection measures by partitioning the contributions of climate change and human activities to NPP changes. The results demonstrated that: 1) the average total and annual NPP values over the years were 209.15 Tg C and 468.06 g C/(m2·yr), respectively. Their trend increasingly fluctuated, with spatial distribution strongly linked to altitude(i.e., lower and higher NPP in high altitude and low altitude areas, respectively) and 2400 m represented the marginal altitude for vegetation differentiation; 2) areas where climate was the main factor affecting NPP accounted for 18.2% of the total research area, whereas human activities were the primary factor influencing NPP in 81.8% of the total research area, which indicated that human activity was the main force driving changes in NPP. Areas where climatic factors(i.e., temperature and precipitation) were the main driving factors occupied 13.6%(temperature) and 6.0%(precipitation) of the total research area, respectively. Therefore, the effect of temperature on NPP changes was stronger than that of precipitation; and 3) the majority of NPP residuals from 2001 to 2014 were positive, with human activities playing an active role in determining regional vegetation growth, possibly due to the return of farmland back to forest and natural forest protection. However, this positive trend is decreasing. This clearly shows the periodical nature of ecological projects and a lack of long-term effectiveness.展开更多
Chlorfluazuron is an insect growth regulator for controlling the major insect pests in crops. This paper describes the effects of sublethal doses (LD10:1.00 ng/larva; LD3o: 3.75 ng/larva) of chlorfluazuron on sper...Chlorfluazuron is an insect growth regulator for controlling the major insect pests in crops. This paper describes the effects of sublethal doses (LD10:1.00 ng/larva; LD3o: 3.75 ng/larva) of chlorfluazuron on spermatogenesis in the adults of the common cutworm, Spodoptera litura (F.). Chlorfluazuron was applied topically to the newly-ecdysed fifth-instars ofS. litura under laboratory conditions. The secondary spermatocytes, spermatids, elongated spermatocytes with mature sperm and eupyrene sperm bundles were present in testis of newly emerged, 1 and 2 day-old adults, but gradually decreased in their numbers in the controls. However, the spermatogonia were not present in newly emerged, 1 and 2 day-old adults. Moreover, primary spermatocytes were present (174 ± 4.0) in newly emerged adults, but not found in 1 and 2 day-old adults. In the testes of newly emerged LD10-treated adults, the numbers of eupyrene and apyrene sperm bundles were significantly reduced compared with controls, and even significantly reduced in LD30-treated adults compared with LDlo, however, their ratios were not affected. Moreover, the pattern of spermatogenesis was the same in LD10- and LD30-treated male adults compared with controls. Furthermore, numbers of developing spermatocytes were significantly reduced in the LD10 compared with controls, and even significantly reduced in LD30-treated male adults compared with LD10. In newly emerged adults, the width and length of elongated spermatocytes with mature sperm were significantly reduced in LDlo- and more significantly reduced in LD30-treated compared with controls of S. litura. In vas deferens of untreated pre- and newly emerged adult male, both eupyrene and apyrene sperm bundles were found, however, in treated pre-adult male, only apyrene sperm bundles and in treated newly emerged adult male, fe, w eupyrene and numerous apyrene sperm bundles were found. It is concluded that spermatogenesis was significantly affected by chlorfluazuron.展开更多
The oxidation of Hg^0 by Pulse Corona Induced Plasma Chemical Process (PPCP) was investigated through changing discharge voltage, pulse frequency and gas compositions. Experimental results indicate that active radic...The oxidation of Hg^0 by Pulse Corona Induced Plasma Chemical Process (PPCP) was investigated through changing discharge voltage, pulse frequency and gas compositions. Experimental results indicate that active radicals including O, O3 and OH can contribute to the oxidation of elemental mercury. 10 kV is the onset voltage, and the higher voltage the better removal efficiency. While with the increase of pulse frequency, the Hg^0 concentration falls rapidly at first but then rises rapidly. The best oxidation condition is at 12 kV and 600-800 PPS. Adding O2 can significantly promote oxidation. With NO and SO2 existed, there is an inhibition of mercury oxidation, and NO has a greater influence. Addition of HCl can promote oxidation slightly but affect the initial concentration of mercury significantly. Little moisture content can promote oxidation, while too much H2O can not only resist the oxidation, but also affect the initial concentration of mercury. The mercury oxidation rate can increase to 97.95% at 12 kV/800 PPS with the system of 10% 02/3% H2O/50 ppm HCI. However, mercury oxidation efficiency can reduce down to 20% with 100 ppm NO added.展开更多
A path following control algorithm for an unmanned underwater vehicle(UUV) using temporary path generation guidance was proposed in this paper.Owing to different initial states of the vehicle,such as position and or...A path following control algorithm for an unmanned underwater vehicle(UUV) using temporary path generation guidance was proposed in this paper.Owing to different initial states of the vehicle,such as position and orientation,the path following control in the horizontal plane may yield a poor performance.To deal with the negative effect induced by initial states,a temporary path generation was presented based on the relationship between the original reference path and the vehicle’s initial states.With different relative positions between the vehicle and reference path,including out of straight lines,as well as inside and outside a circle,the related temporary paths guiding the vehicle to the reference path were able to be generated in real time.The vehicle was guided to steer along the temporary path until it reached the tangent point at the reference path,where the controller was designed using the input-output feedback linearization method.Simulation results demonstrated that the proposed algorithm is effective under the three different situations mentioned above.展开更多
Objective:This study aimed to identify the challenges of community health nurses(CHNs)in delivering effective community health care to achieve universal health coverage(UHC)in Myanmar.Methods:A total of 30 CHNs from t...Objective:This study aimed to identify the challenges of community health nurses(CHNs)in delivering effective community health care to achieve universal health coverage(UHC)in Myanmar.Methods:A total of 30 CHNs from township health centers in the northeastern,southern,and western parts of Myanmar were purposefully recruited for quantitative and qualitative interviews.Quantitative data were processed using Microsoft Excel software,and qualitative data were analyzed using thematic analysis.This study is registered with researchregistry6201.Results:Around the country,30 CHNs uncovered their hardships in implementing primary health care to achieve UHC.Over 90%of the participants agreed to the problem of inadequate health infrastructure,while half of them felt unmotivated when they encountered role conflicts among various cadres of healthcare providers and poor opportunities for career promotion.Major problems arose from the lack of standard professional education at the entry point to community settings because most CHNs did not achieve specialized training in providing public health services.Complications are incapable of evaluating health services for policy-making and the inability to conduct health research to develop evidencebased practices.Insecure work and living conditions,unsupportive community relationships,and undereducation in professional practices were supportive major themes explored by CHNs to achieve a deeper understanding of the barriers to UHC.Not only the health system itself but also the population and other geographical factors have contributed to many challenges to CHNs.Conclusion:Myanmar’s CHNs face many challenges in achieving UHC.These challenges are not confined to the health sector.Some situations,such as geographical barriers and transportation problems,remain persistent challenges for healthcare providers.This study highlights the fact that current health systems should be strengthened by qualified healthcare providers and sufficient infrastructure.Meanwhile,public empowerment plays a critical role in promoting health development.展开更多
The standing stock and primary production of benthic microalgae on tidal flats were measured seasonally at 3 transects (Puqing, Dahengchuang and Puqi) in Yueqing Bay during 2002 2003. The results showed that the integ...The standing stock and primary production of benthic microalgae on tidal flats were measured seasonally at 3 transects (Puqing, Dahengchuang and Puqi) in Yueqing Bay during 2002 2003. The results showed that the integral chlorophyll a (Chl a) concentration in tidal flat mud exhibited a seasonal variation with the order of magnitude: winter (14.0 4.2 mg m-2) > spring (13.0 6.3 mg m-2) > autumn (7.7 5.9 mg m-2) > summer (4.6 3.2 mg m-2). The primary production showed an order of magnitude: spring (270.5 224.9 mgC m-2 d-1)>winter (238.7 225.5 mgC m-2 d-1)>autumn (214.1 56.2 mgC m-2 d-1)>summer (71.6 44.6 mgC m-2 d-1). Both chlorophyll a and primary production showed maximum values in the surface layer of sediment, and decreased rapidly with increasing depth due to sun light limitation. The results of variance analysis indicated that seasonal variation and tidal flat condition affected Chl a greatly, but had no significant effect on primary production. The annual primary production of benthic microalgae on tidal flats in Yueqing Bay was estimated at 16143 tons carbon, which is sufficient to support 1.02×105 tons shellfish production. The environmental factors affecting chlorophyll and primary production on the tidal flats in Yueqing Bay were discussed. By comparing with other bays on China's coast, it was observed that Yueqing Bay is a region with high benthic microalgae standing crop and primary production, which may be related to the type of its sediment.展开更多
In this paper, we derive a lattice model for a single species on infinite patches of one-dimensional space with that the maturation could occur at any age. The formulation involves a distribution of possible ages of m...In this paper, we derive a lattice model for a single species on infinite patches of one-dimensional space with that the maturation could occur at any age. The formulation involves a distribution of possible ages of maturation and a probability density function on which ecological assumptions are made. The following results are obtained: the existence and isotropy of the unique nonnegative solution for initial value problem, the extinction of the species provided with the non-existence of positive equilibria, and the existence of wavefronts with the wave speed c 〉 c*.展开更多
Grassland degradation in Altay Prefecture is of considerable concern as it is a threat that hinders the sustainable development of the local economy and the stable operation of the livestock industry.Quantitative asse...Grassland degradation in Altay Prefecture is of considerable concern as it is a threat that hinders the sustainable development of the local economy and the stable operation of the livestock industry.Quantitative assessment of the relative contributions of climate change and human activities,which are considered as the dominant triggers of grassland degradation,to grassland variation is crucial for understanding the grassland degradation mechanism and mitigating the degraded grassland in Altay Prefecture.In this paper,the Carnegie-Ames-Stanford Approach model and the Thornthwaite memorial model were adopted to simulate the actual net primary productivity(NPP_(A))and potential net primary productivity(NPP_(P))in the Altay Prefecture from 2000 to 2019.Meanwhile,the difference between potential NPP and actual NPP was employed to reflect the effects of human activities(NPP_(H))on the grassland.On this basis,we validated the viability of the simulated NPP using the Pearson correlation coefficient,investigated the spatiotemporal variability of grassland productivity,and established comprehensive scenarios to quantitatively assess the relative roles of climate change and human activities on grassland in Altay prefecture.The results indicate three main points.(1)The simulated NPP_(A) was highly consistent with the MOD17 A3 dataset in spatial distribution.(2)Regions with an increased NPP_(A) accounted for 70.53% of the total grassland,whereas 29.47% of the total grassland area experienced a decrease.At the temporal scale,the NPP_(A) presented a slightly increasing trend(0.83 g C m^(-2) yr^(-1))over the study period,while the trends of NPP_(P) and NPP_(H) were reduced(-1.31 and-2.15 g C m^(-2) yr^(-1)).(3)Compared with climate change,human activities played a key role in the process of grassland restoration,as 66.98% of restored grassland resulted from it.In contrast,inter-annual climate change is the primary cause of grassland degradation,as it influenced 55.70% of degraded grassland.These results could shed light on the mechanisms of grassland variation caused by climate change and human activities,and they can be applied to further develop efficient measures to combat desertification in Altay Prefecture.展开更多
The authors are concerned with a zero-flux type initial boundary value problem for scalar conservation laws.Firstly,a kinetic formulation of entropy solutions is established.Secondly,by using the kinetic formulation a...The authors are concerned with a zero-flux type initial boundary value problem for scalar conservation laws.Firstly,a kinetic formulation of entropy solutions is established.Secondly,by using the kinetic formulation and kinetic techniques,the uniqueness of entropy solutions is obtained.Finally,the parabolic approximation is studied and an error estimate of order η 1/3 between the entropy solution and the viscous approximate solutions is established by using kinetic techniques,where η is the size of artificial viscosity.展开更多
文摘Autonomous vehicle technology will transform fundamentally urban traffic systems.To better enhance the coming era of connected and autonomous vehicles,effective control strategies that interact wisely with these intelligent vehicles for signalized at-grade intersections are indispensable.Vehicle-to-infrastructure communication technology offers unprecedented clues to reduce the delay at signalized intersections by innovative information-based control strategies.This paper proposes a new dynamic control strategy for signalized intersections with vehicle-to-signal information.The proposed strategy is called periodic vehicle holding(PVH)strategy while the traffic signal can provide information for the vehicles that are approaching an intersection.Under preliminary autonomous vehicle(PAV)environment,left-turning and through-moving vehicles will be sorted based on different information they receive.The paper shows how PVH reorganizes traffic to increase the capacity of an intersection without causing severe spillback to the upstream intersection.Results show that PVH can reduce the delay by approximately 15%at a signalized intersection under relatively high traffic demand.
基金National 973 Project No.2002CB412507+5 种基金 National Natural Science Foundation of China No.90202002 Knowledge Innovation Project of IGSNRR CAS No.CXIOG-E01-02-04 One Hundred Talents Program of CAS.
文摘Combined with recent historical climate data and two periods of land use datasets from remote sensing data, we test the net primary productivity (NPP) data sets in North Chinamodelled by the satellite data-driven Global Production Efficiency Model (GLO-PEM) for detecting thewidespread spatial and temporal characteristics of the impacts of climate and land use change onthe regional NPP. Our results show that over the past 20 years, the mean annual temperature in thestudy region has remarkably increased by more than 0.064 ℃, but over the same period, there hasbeen a 1.49 mm decrease in annual precipitation and decrease in NPP by an annual rate of 6.9 TgC.The NPP changes in the study region were greatly affected by the average temperature andprecipitation by ten-day periods as well as the seasonal temperature and precipitation in the studyregion. The correlation between seasonal NPP and seasonal precipitation and temperature is highlyconsistent with land cover spatially, and the correlation coefficient changes with the changes ofvegetation types. The analysis reveals that the related areas in land use change only take up 5.45%of the whole studied region, so the climate changes dominate the impacts on the NPP in the wholestudy region (90% of the total). However, land use plays an absolute dominative role in areas withland cover changes, accounting for 97% of the total. From 1981 to 2000, the NPP in the whole studyregion remarkably reduced due to obvious precipitation decrease and temperature rise. Between twoperiods of land use (about 10 years), the changes in climate are predicted to promote a decrease inNPP by 78 ( + -0.6) TgC, and integrated impacts of climate changes and land use to promote adecrease in NPP by 87(+-0.8) TgC.
文摘AIM:Many defense factors of the mother's colostrum or milk protect infants from intestinal, respiratory and systemic infections. In the present study, we investigated the effect of colostrum and mature human milk on E. histolytica parasites in vitro.METHODS:Samples of human milk were collected from 5 healthy lactating mothers.The medium with human milk at concentrations of 2%, 5% and 10% was obtained.RESULTS:The lethal effect of E. histolytica on the medium supplemented with different concentrations of both colostrum and mature human milk was significant during the first 30min. We also detected that the results of colostrum and mature human milk were similar. No statistically significant differences were found between same concentrations of colostrum and mature human milk at the same times.CONCLUSION:Colostrum and mature human milk have significant lethal effect on E. histolytica and protect against its infection in breast fed children.
基金Supported by Grants from the Ministry of Health of China,No.200902002-8Grants from Cancer Institute/Hospital Chinese Academy of Medical Sciences and Peking Union Medical College,No.2009YF50
文摘AIM:To explore the DNA image cytometry (DNA-ICM) technique as a primary screening method for esopha-geal squamous precancerous lesions.METHODS:This study was designed as a population-based screening study.A total of 582 local residents aged 40 years-69 years were recruited from Linzhou in Henan and Feicheng in Shandong.However,only 452 subjects had results of liquid-based cytology,DNA-ICM and pathology.The sensitivity and specificity of DNA-ICM were calculated and compared with liquid-based cytology in moderate dysplasia or worse.RESULTS:Sensitivities of DNA-ICM ranging from at least 1 to 4 aneuploid cells were 90.91%,86.36%,79.55% and 77.27%,respectively,which were better than that of liquid-based cytology (75%).Specifici-ties of DNA-ICM were 70.83%,84.07%,92.65% and 96.81%,but the specificity of liquid-based cytology was 91.91%.The sensitivity and specificity of a combination of liquid-based cytology and DNA-ICM were 84.09% and 85.78%,respectively.CONCLUSION:It is possible to use DNA-ICM tech-nique as a primary screening method for esophageal squamous precancerous lesions.
文摘Objectives:Effective and efficient communication is a core element in healthcare systems,especially between healthcare providers and patients.This study aimed to identify communication barriers be-tween nurses and patients in primary healthcare centers in Bahrain.Methods:This is a cross-sectional study conducted across primary healthcare centers in Bahrain.Four hundred and two patients were recruited using convenience sampling.A self-administered question-naire comprising 29 items on communication barriers was used.Results:A total of 402 patients consented to participate.The majority of participants reported the following statements had large effects on communication:“shortage in the number of nurses compared to the large number of patients”(254/401,63.3%),“lack of desire of nurse to communicate with patients”(246/402,61.2%),and“negative attitude of the nurse toward the patient”(238/401,59.4%).Further,“difference in language between nurses and patients,”“lack of self-confidence by nurses,”and“nurses overwhelmed by work”were ranked as top three statements with a significant influence on commu-nication between nurses and patients.Conclusions:Communication between healthcare providers and patients is pivotal for an optimal healthcare service.Based on the findings of this study and the literature,we recommend formal training of health care workers in improving communication skills and including this not only in medical cur-riculum but also in the form of continuing medical education(CMEs)1.
基金Under the auspices of National Key Basic Research Program of China(No.2015CB452706)National Natural Science Foundation of China(No.41401198,41571527)+1 种基金Youth Talent Team Program of the Institute of Mountain Hazards and Environment,Chinese Academy of Sciences(No.SDSQB-2015-01)Youth Innovation Promotion Association,Chinese Academy of Sciences(No.2016332)
文摘Net primary productivity(NPP), a metric used to define and identify changes in plant communities, is greatly affected by climate change, human activities and other factors. Here, we used the Carnegie-Ames-Stanford Approach(CASA) model to estimate the NPP of plant communities in Hengduan Mountains area of China, and to explore the relationship between NPP and altitude in this region. We examined the mechanisms underlying vegetation growth responses to climate change and quantitatively assessed the effects of ecological protection measures by partitioning the contributions of climate change and human activities to NPP changes. The results demonstrated that: 1) the average total and annual NPP values over the years were 209.15 Tg C and 468.06 g C/(m2·yr), respectively. Their trend increasingly fluctuated, with spatial distribution strongly linked to altitude(i.e., lower and higher NPP in high altitude and low altitude areas, respectively) and 2400 m represented the marginal altitude for vegetation differentiation; 2) areas where climate was the main factor affecting NPP accounted for 18.2% of the total research area, whereas human activities were the primary factor influencing NPP in 81.8% of the total research area, which indicated that human activity was the main force driving changes in NPP. Areas where climatic factors(i.e., temperature and precipitation) were the main driving factors occupied 13.6%(temperature) and 6.0%(precipitation) of the total research area, respectively. Therefore, the effect of temperature on NPP changes was stronger than that of precipitation; and 3) the majority of NPP residuals from 2001 to 2014 were positive, with human activities playing an active role in determining regional vegetation growth, possibly due to the return of farmland back to forest and natural forest protection. However, this positive trend is decreasing. This clearly shows the periodical nature of ecological projects and a lack of long-term effectiveness.
文摘Chlorfluazuron is an insect growth regulator for controlling the major insect pests in crops. This paper describes the effects of sublethal doses (LD10:1.00 ng/larva; LD3o: 3.75 ng/larva) of chlorfluazuron on spermatogenesis in the adults of the common cutworm, Spodoptera litura (F.). Chlorfluazuron was applied topically to the newly-ecdysed fifth-instars ofS. litura under laboratory conditions. The secondary spermatocytes, spermatids, elongated spermatocytes with mature sperm and eupyrene sperm bundles were present in testis of newly emerged, 1 and 2 day-old adults, but gradually decreased in their numbers in the controls. However, the spermatogonia were not present in newly emerged, 1 and 2 day-old adults. Moreover, primary spermatocytes were present (174 ± 4.0) in newly emerged adults, but not found in 1 and 2 day-old adults. In the testes of newly emerged LD10-treated adults, the numbers of eupyrene and apyrene sperm bundles were significantly reduced compared with controls, and even significantly reduced in LD30-treated adults compared with LDlo, however, their ratios were not affected. Moreover, the pattern of spermatogenesis was the same in LD10- and LD30-treated male adults compared with controls. Furthermore, numbers of developing spermatocytes were significantly reduced in the LD10 compared with controls, and even significantly reduced in LD30-treated male adults compared with LD10. In newly emerged adults, the width and length of elongated spermatocytes with mature sperm were significantly reduced in LDlo- and more significantly reduced in LD30-treated compared with controls of S. litura. In vas deferens of untreated pre- and newly emerged adult male, both eupyrene and apyrene sperm bundles were found, however, in treated pre-adult male, only apyrene sperm bundles and in treated newly emerged adult male, fe, w eupyrene and numerous apyrene sperm bundles were found. It is concluded that spermatogenesis was significantly affected by chlorfluazuron.
文摘The oxidation of Hg^0 by Pulse Corona Induced Plasma Chemical Process (PPCP) was investigated through changing discharge voltage, pulse frequency and gas compositions. Experimental results indicate that active radicals including O, O3 and OH can contribute to the oxidation of elemental mercury. 10 kV is the onset voltage, and the higher voltage the better removal efficiency. While with the increase of pulse frequency, the Hg^0 concentration falls rapidly at first but then rises rapidly. The best oxidation condition is at 12 kV and 600-800 PPS. Adding O2 can significantly promote oxidation. With NO and SO2 existed, there is an inhibition of mercury oxidation, and NO has a greater influence. Addition of HCl can promote oxidation slightly but affect the initial concentration of mercury significantly. Little moisture content can promote oxidation, while too much H2O can not only resist the oxidation, but also affect the initial concentration of mercury. The mercury oxidation rate can increase to 97.95% at 12 kV/800 PPS with the system of 10% 02/3% H2O/50 ppm HCI. However, mercury oxidation efficiency can reduce down to 20% with 100 ppm NO added.
基金Supported by the National Natural Science Foundation of China under Grant No.51179038the Program of New Century Excellent Talents in University under Grant No. NCET-10-0053
文摘A path following control algorithm for an unmanned underwater vehicle(UUV) using temporary path generation guidance was proposed in this paper.Owing to different initial states of the vehicle,such as position and orientation,the path following control in the horizontal plane may yield a poor performance.To deal with the negative effect induced by initial states,a temporary path generation was presented based on the relationship between the original reference path and the vehicle’s initial states.With different relative positions between the vehicle and reference path,including out of straight lines,as well as inside and outside a circle,the related temporary paths guiding the vehicle to the reference path were able to be generated in real time.The vehicle was guided to steer along the temporary path until it reached the tangent point at the reference path,where the controller was designed using the input-output feedback linearization method.Simulation results demonstrated that the proposed algorithm is effective under the three different situations mentioned above.
基金This work was supported by the Ministry of Health and Sports,Republic of the Union of Myanmar(MOHS IR Grant 2019,Research ID No.501).
文摘Objective:This study aimed to identify the challenges of community health nurses(CHNs)in delivering effective community health care to achieve universal health coverage(UHC)in Myanmar.Methods:A total of 30 CHNs from township health centers in the northeastern,southern,and western parts of Myanmar were purposefully recruited for quantitative and qualitative interviews.Quantitative data were processed using Microsoft Excel software,and qualitative data were analyzed using thematic analysis.This study is registered with researchregistry6201.Results:Around the country,30 CHNs uncovered their hardships in implementing primary health care to achieve UHC.Over 90%of the participants agreed to the problem of inadequate health infrastructure,while half of them felt unmotivated when they encountered role conflicts among various cadres of healthcare providers and poor opportunities for career promotion.Major problems arose from the lack of standard professional education at the entry point to community settings because most CHNs did not achieve specialized training in providing public health services.Complications are incapable of evaluating health services for policy-making and the inability to conduct health research to develop evidencebased practices.Insecure work and living conditions,unsupportive community relationships,and undereducation in professional practices were supportive major themes explored by CHNs to achieve a deeper understanding of the barriers to UHC.Not only the health system itself but also the population and other geographical factors have contributed to many challenges to CHNs.Conclusion:Myanmar’s CHNs face many challenges in achieving UHC.These challenges are not confined to the health sector.Some situations,such as geographical barriers and transportation problems,remain persistent challenges for healthcare providers.This study highlights the fact that current health systems should be strengthened by qualified healthcare providers and sufficient infrastructure.Meanwhile,public empowerment plays a critical role in promoting health development.
基金supported by the National Marine Public-interest Project (No. 200705024)the National ‘908’ Project (No. 908-02-04-07)+1 种基金National ‘973’ Project (No. 2006CB400605)Zhejiang Province Marine Development Management Project (No. ZJ0201)
文摘The standing stock and primary production of benthic microalgae on tidal flats were measured seasonally at 3 transects (Puqing, Dahengchuang and Puqi) in Yueqing Bay during 2002 2003. The results showed that the integral chlorophyll a (Chl a) concentration in tidal flat mud exhibited a seasonal variation with the order of magnitude: winter (14.0 4.2 mg m-2) > spring (13.0 6.3 mg m-2) > autumn (7.7 5.9 mg m-2) > summer (4.6 3.2 mg m-2). The primary production showed an order of magnitude: spring (270.5 224.9 mgC m-2 d-1)>winter (238.7 225.5 mgC m-2 d-1)>autumn (214.1 56.2 mgC m-2 d-1)>summer (71.6 44.6 mgC m-2 d-1). Both chlorophyll a and primary production showed maximum values in the surface layer of sediment, and decreased rapidly with increasing depth due to sun light limitation. The results of variance analysis indicated that seasonal variation and tidal flat condition affected Chl a greatly, but had no significant effect on primary production. The annual primary production of benthic microalgae on tidal flats in Yueqing Bay was estimated at 16143 tons carbon, which is sufficient to support 1.02×105 tons shellfish production. The environmental factors affecting chlorophyll and primary production on the tidal flats in Yueqing Bay were discussed. By comparing with other bays on China's coast, it was observed that Yueqing Bay is a region with high benthic microalgae standing crop and primary production, which may be related to the type of its sediment.
基金This research is Supported by Natural Science Fundation of China and Guangdong Province(04010364).
文摘In this paper, we derive a lattice model for a single species on infinite patches of one-dimensional space with that the maturation could occur at any age. The formulation involves a distribution of possible ages of maturation and a probability density function on which ecological assumptions are made. The following results are obtained: the existence and isotropy of the unique nonnegative solution for initial value problem, the extinction of the species provided with the non-existence of positive equilibria, and the existence of wavefronts with the wave speed c 〉 c*.
基金The Science and Technology Project of Xizang Autonomous Region(XZ201901-GA-07)The Key Research and Development Project of Sichuan Science and Technology Department(2021YFQ0042)The Science and Technology Bureau of Altay Region in Yili Kazak Autonomous Prefecture(Y99M4600AL)。
文摘Grassland degradation in Altay Prefecture is of considerable concern as it is a threat that hinders the sustainable development of the local economy and the stable operation of the livestock industry.Quantitative assessment of the relative contributions of climate change and human activities,which are considered as the dominant triggers of grassland degradation,to grassland variation is crucial for understanding the grassland degradation mechanism and mitigating the degraded grassland in Altay Prefecture.In this paper,the Carnegie-Ames-Stanford Approach model and the Thornthwaite memorial model were adopted to simulate the actual net primary productivity(NPP_(A))and potential net primary productivity(NPP_(P))in the Altay Prefecture from 2000 to 2019.Meanwhile,the difference between potential NPP and actual NPP was employed to reflect the effects of human activities(NPP_(H))on the grassland.On this basis,we validated the viability of the simulated NPP using the Pearson correlation coefficient,investigated the spatiotemporal variability of grassland productivity,and established comprehensive scenarios to quantitatively assess the relative roles of climate change and human activities on grassland in Altay prefecture.The results indicate three main points.(1)The simulated NPP_(A) was highly consistent with the MOD17 A3 dataset in spatial distribution.(2)Regions with an increased NPP_(A) accounted for 70.53% of the total grassland,whereas 29.47% of the total grassland area experienced a decrease.At the temporal scale,the NPP_(A) presented a slightly increasing trend(0.83 g C m^(-2) yr^(-1))over the study period,while the trends of NPP_(P) and NPP_(H) were reduced(-1.31 and-2.15 g C m^(-2) yr^(-1)).(3)Compared with climate change,human activities played a key role in the process of grassland restoration,as 66.98% of restored grassland resulted from it.In contrast,inter-annual climate change is the primary cause of grassland degradation,as it influenced 55.70% of degraded grassland.These results could shed light on the mechanisms of grassland variation caused by climate change and human activities,and they can be applied to further develop efficient measures to combat desertification in Altay Prefecture.
基金supported by the National Natural Science Foundation of China (No. 10971135)the Program for New Century Excellent Talents of the Ministry of Education of China (No. NCET-07-0546)+2 种基金the University Young Teacher Sciences Foundation of Anhui Province (No. 2010SQRL145)Shanghai Jiao Tong University Innovation Fund for Postgraduates (No. AE071202)the Quality Project Fund of Fuyang Teachers College (No. 2010JPKC07)
文摘The authors are concerned with a zero-flux type initial boundary value problem for scalar conservation laws.Firstly,a kinetic formulation of entropy solutions is established.Secondly,by using the kinetic formulation and kinetic techniques,the uniqueness of entropy solutions is obtained.Finally,the parabolic approximation is studied and an error estimate of order η 1/3 between the entropy solution and the viscous approximate solutions is established by using kinetic techniques,where η is the size of artificial viscosity.