On the tranquil waters of Xiaoshanyang,a small lake in Deqing County,Zhejiang Province,rows of white,spherical buoys are lined up in perfect order,resembling strands of pearl necklaces.Once a thousand-year-old pearl-f...On the tranquil waters of Xiaoshanyang,a small lake in Deqing County,Zhejiang Province,rows of white,spherical buoys are lined up in perfect order,resembling strands of pearl necklaces.Once a thousand-year-old pearl-farming site,this heritage-rich waterbody has emerged as a global benchmark for the preservation of agricultural heritage.展开更多
AIM:To summarize 10 surgical pearls for managing proliferative diabetic retinopathy(PDR)adapted from the ancient Chinese allusions and analyze the application of these pearls in a real-world fashion.METHODS:Retrospect...AIM:To summarize 10 surgical pearls for managing proliferative diabetic retinopathy(PDR)adapted from the ancient Chinese allusions and analyze the application of these pearls in a real-world fashion.METHODS:Retrospective,noncomparative,interventional study.Ten surgical pearls were summarized and adapted from the ancient Chinese philosophy.Totally 346 cases(443 eyes)that underwent pars plana vitrectomy(PPV)at our hospial from January 2016 to February 2024 were selected.Flexible combinations of these pearls were applied according to the specific condition of each patient during surgeries.The efficacy and safety were analyzed,as well as the application frequencies according to the existence of tractional retinal detachment or not.RESULTS:A total of 473 times of surgeries were performed on all the patients.According to ancient Chinese allusions,ten surgical pearls were summarized from these surgeries.All PPVs went smoothly with the application of different combinations.Finally,almost all proliferative membranes were successfully peeled except for 10 patients(11 eyes),who went through strategy No.10(minimal membranectomy)that,only necessary relaxation incisions were made with most of the proliferative membranes left on purpose.The final visual acuities were mostly improved or stable(1.92±0.83 LogMAR preoperatively vs 1.16±0.85 LogMAR postoperatively,P<0.01).Postoperative complications mainly included early inflammatory responses in the anterior chamber and nuclear sclerosis.Recurrent vitreous hemorrhage,retinal detachment,and hyphema or neovascular glaucoma occurred in 1.9%(9/473),3.2%(15/473),0.4%(2/473)and 0.4%(2/473)times of PPVs,respectively.After 12/473(2.5%)times of PPVs,retinal detachment at the macular area still existed,and multiple times of subsequent PPVs were conducted.Final retinal attachment at the macular area was realized in 98.9%eyes.Those 5 unattached eyes were with heavily reproliferated membranes and subsequent tractional retinal detachment recurrence under the oil,and three of them were scleral buckled additionally.CONCLUSION:These 10 surgical strategies and technique pearls were mostly effective and safe in the management of severe PDR patients.They were relatively easy to be memorized and applicated once the meaning of each Chinese idiom was understood.One can use different combinations flexibly according to a patient’s specific condition.展开更多
Black tents,also known as black yak-wool tents due to their construction from yak wool,serve as the traditional accommodation for ethnic Tibetan nomads.From ancient times till now,these tents have long captured the no...Black tents,also known as black yak-wool tents due to their construction from yak wool,serve as the traditional accommodation for ethnic Tibetan nomads.From ancient times till now,these tents have long captured the nomadic life of herdsmen living on the Qinghai-Xizang Plateau.展开更多
The transition of the superficial microstmcture of freshwater pearls induced by Ce was investigated by means of scanning electron microscopy. The pearls were cultured in freshwater containing 0 （control group ）, 0.5...The transition of the superficial microstmcture of freshwater pearls induced by Ce was investigated by means of scanning electron microscopy. The pearls were cultured in freshwater containing 0 （control group ）, 0.5, 1, and 1.5 mg·L^-1 of a Ce additive. X-ray photoelectron spectroscopy （XPS） measurement showed that the concentration of Ce absorbed in the superficial microstmcture of pearls was positively correlated to the additive Ce. At the same time, the surface microstmcture of pearls changed greatly with Ce concentration, the shape of the blocks changed from spindly to perfect regular hexagonal sheets and finally to round discs. The glossiness of the pearls changed correspondingly with the microstmcture, pearls possessing the regular hexagonal blocks having the highest glossiness. Therefore, the REE Ce exerted a significant influence on the microstructure and glossiness of freshwater pearls. An appropriate quantity of Ce may improve the glossiness of pearls.展开更多
Now, GISs are popular at most major cities along the coast in China. The lack of available digital geographic data is a serious bottleneck problem. This article first analyses the development characteristics of urban ...Now, GISs are popular at most major cities along the coast in China. The lack of available digital geographic data is a serious bottleneck problem. This article first analyses the development characteristics of urban planning and management information system in China, and proposes a method for establishing a planning and management information system for small town. By using GIS as core and integrating with microcomputer network, office automation (OA), computer aided design (CAD), and multimedia technology, a microcomputer information system (TownMIS) is implemented after 3 year design and development. It may be a first comprehensive system for the planning and management of small towns. Since the January of 1996, TownMIS has been actually used in Xiaolan Town, a coastal rich town in South China. This has provided perfect technical, managerial, operational and institutional references for resolving the contradiction of the fast growing installation of GIS sites and fewer actually running system.展开更多
The concept of urban green space system planning was proposed after analyzing the background of compiling Guangzhou green space system planning and current situation of local green spaces,i.e. design landscape pattern...The concept of urban green space system planning was proposed after analyzing the background of compiling Guangzhou green space system planning and current situation of local green spaces,i.e. design landscape pattern of Guangzhou City during urban agglomeration of the Pearl River Delta,and highlight Lingnan cultures(Lingnan refers to south of the Five Ridges) and features of "Flower City"(another name of Guangzhou). Key points of planning are protecting ecological barriers in the north,improving urban garden structure in the center,using wetland reasonably in the south,to maintain integrality and continuity of the landscape pattern.展开更多
EDSS is a comprehensive software system for water quality management in tidal river networks in general and for the Pearl River Delta in particular. Its purpose is to provide a practical tool that could assist governm...EDSS is a comprehensive software system for water quality management in tidal river networks in general and for the Pearl River Delta in particular. Its purpose is to provide a practical tool that could assist government agencies in decision making for the efficient management of water resources in terms of both quantity and quality. By combining the capabilities of geographical information system (GIS), database management system (DBMS), model base management system (MBMS) and expert system, the aim is to improve the quality of decision making in what is becoming an increasingly complex area. This paper first outlines the basic concepts and philosophy adopted in developing EDSS, the system architecture, design features, implementation techniques and facilities provided. Thereafter, the core part of the system—the hydrodynamic and water quality models are described briefly. The final contribution in this paper describes the application of EDSS to the Pearl River Delta, which has the most complicated tidal river network patterns as well as the fastest economic development in the world. Examples are given of the real-world problems that can be addressed using the system, including cross-boundary water pollution analysis, regional drinking water take-up site selection, screening of important polluters, environmental impact assessment, and water quality zoning and planning. It is illustrated that EDSS can provide efficient and scientific analytical tools for planning and decision-making purposes in the information era.展开更多
The growth of peripheral ports to dominant hubs has been well documented in North America and Europe,and has led to the elaboration of several theoretical models.However,although changes in containerization growth hav...The growth of peripheral ports to dominant hubs has been well documented in North America and Europe,and has led to the elaboration of several theoretical models.However,although changes in containerization growth have been taking place in the South and East Asia in recent years,particularly in China,only a few studies have fo-cused on this region.The Pearl(Zhujiang) River Delta(PRD) has a typical port system with hub and peripheral ports,and provides an excellent case for studying the Peripheral Challenge.This paper introduces the theoretical evidence of the Hayuth model and analyzes the evolution of the container port system in the PRD with five phases:1) phase I:preconditions for change and phase II:initial container port development in the 1970s and early 1980s;2) phase III:diffusion,consolidation,and port concentration in the middle and late 1980s;3) phase IV:the load center in the 1990s;and(4) phase V:the Peripheral Challenge since the late 1990s.The results illustrate that the Shenzhen port presents mounting challenges to the Hong Kong port,descending from a transshipment hub of China to a regional load center of Southeast China.Furthermore,this paper explores five points that have led to the evolution of the port system in the PRD:1) competition in the regional port systems;2) different interested parties;3) shift of investment strategies of in-ternational terminal operators;4) integration of shipping networks and reorganization of carriers;and 5) cost-based competition.展开更多
Optical and micro-infrared microscope were used to observe the internal structure and mineral composition of high and low quality Chinese seawater and freshwater cultured pearls.Results clearly reveal that aragonite a...Optical and micro-infrared microscope were used to observe the internal structure and mineral composition of high and low quality Chinese seawater and freshwater cultured pearls.Results clearly reveal that aragonite and calcite are found in seawater cultured pearls,but vaterite is not found.In contrast,vaterite and aragonite are found in freshwater cultured pearls,but calcite is not found.Based on our analysis and observations of the internal structure of high and low quality cultured pearls,a modified integrated model of the internal structure of Chinese cultured pearls was established.Our revisions to the previous model focus on significant differences within the prismatic layer of Chinese cultured pearls.展开更多
AIM: To compare surgical peeling and aspiration and neodymium yttrium garnet laser capsulotomy for pearl form of posterior capsule opacification(PCO).METHODS: A prospective, randomized, double blind,study was done at ...AIM: To compare surgical peeling and aspiration and neodymium yttrium garnet laser capsulotomy for pearl form of posterior capsule opacification(PCO).METHODS: A prospective, randomized, double blind,study was done at Rotary Eye Hospital, Maranda,Palampur, India, Santosh Medical College Hospital,Ghaziabad, India and Laser Eye Clinic, Noida India.Consecutive patients with pearl form of PCO following surgery, phacoemulsification, manual small incision cataract surgery and conventional extracapsular cataract extraction(ECCE) for age related cataract, were randomized to have peeling and aspiration or neodymium yttrium garnet laser capsulotomy. Corrected distance visual acuity(CDVA), intra-operative and postoperative complications were compared.RESULTS: A total of 634 patients participated in the study, and 314(49.5%) patients were randomized to surgical peeling and aspiration group and 320(50.5%) to the Nd:YAG laser group. The mean pre-procedural log MAR CDVA in peeling and neodymium: yttrium-aluminium-garnet(Nd:YAG) laser group was 0.80 ±0.25 and 0.86 ±0.22, respectively. The mean final CDVA in peeling group(0.22 ±0.23) was comparable to Nd:YAG group(0.24 ±0.28; t-test, P =0.240). There was a significant improvement in vision after both the procedures(P 【0.001). A slightly higher percentage of patients in Nd:YAG laser group(283/88.3%) than in peeling group(262/83.4%) had a CDVA of 0.5(20/63) or better at 9mo(P 【0.001). On the contrary, patients havingCDVA worse than 1.00(20/200) was also significantly higher in Nd:YAG laser group as compared to peeling group(25/7.7% vs 15/4.7%, respectively). On application of ANCOVA, there was less than 0.001% risk that PCO thickness and total laser energy had no effect on rate of complications in Nd:YAG laser group and less than 0.001% risk that PCO thickness had no effect on complications in peeling group respectively. Sum of square analysis suggests that in the Nd:YAG laser group,thick PCO had a stronger impact on complications(Fischer test probability, P r 【0.0001) than thin PCO and total laser energy(Fischer test probability, P r 【0.002),respectively; similarly, in peeling group, thick PCO and preoperative vision had a stronger effect on complications than thin PCO, respectively(Fischer test probability, P r 【0.001). The rate of complications like uveitis(P =0.527) and cystoid macular edema(P =0.068),did not differ significantly between both the groups.However, intraocular pressure spikes(P =0.046) and retinal detachment(P【0.001) were significantly higher in Nd:YAG laser group as compared to peeling group.Retinal detachment was more common in patients having degenerative myopia(7/87.5%, P 【0.001). Recurrence of pearls was the most common cause of reduction of vision in the peeling group(24/7.6%, P 【0.001).CONCLUSION: There is no alternative to Nd:YAG laser capsulotomy for fibrous subtype of PCO. For pearl form of PCO, both techniques are comparable with regard to visual outcomes. Nd:YAG laser capsulotomy has a higher incidence of IOP spikes and retinal detachment whereas recurrence of pearls may occur after successful peeling and aspiration. When posterior capsulotomy is needed in patients with retinal degenerations,retinopathies and pre-existing retinal breaks, the clinician should be cautious about increased risks of possible complications of Nd:YAG laser capsulotomy.展开更多
In this article we explored the crystal structure of a few pearls and shellfish's shell of fresh water and sea water, and found that pearls and nacreous layer (perhaps and prismatic layer) of shells are all the sa...In this article we explored the crystal structure of a few pearls and shellfish's shell of fresh water and sea water, and found that pearls and nacreous layer (perhaps and prismatic layer) of shells are all the same: CaCO3, orthorhombic system, aragonite structure and the value of lattice spacings are almost identical. This shows that the pearls of fresh water and sea water are all the same in nature.展开更多
A rhombic planform nonlinear cross-diffusive instability analysis is applied to a particular interaction-diffusion plant-ground water model system in an arid flat environment. This model contains a plant root suction ...A rhombic planform nonlinear cross-diffusive instability analysis is applied to a particular interaction-diffusion plant-ground water model system in an arid flat environment. This model contains a plant root suction effect as a cross-diffusion term in the ground water equation. In addition a threshold-dependent paradigm that differs from the usually employed implicit zero-threshold methodology is introduced to interpret stable rhombic patterns. These patterns are driven by root suction since the plant equation does not yield the required positive feedback necessary for the generation of standard Turing-type self-diffusive instabilities. The results of that analysis can be represented by plots in a root suction coefficient versus rainfall rate dimensionless parameter space. From those plots regions corresponding to bare ground and vegetative patterns consisting of isolated patches, rhombic arrays of pseudo spots or gaps separated by an intermediate rectangular state, and homogeneous distributions from low to high density may be identified in this parameter space. Then, a morphological sequence of stable vegetative states is produced upon traversing an experimentally-determined root suction characteristic curve as a function of rainfall through these regions. Finally, that predicted sequence along a rainfall gradient is compared with observational evidence relevant to the occurrence of leopard bush, pearled bush, or labyrinthine tiger bush vegetative patterns, used to motivate an aridity classification scheme, and placed in the context of some recent biological nonlinear pattern formation studies.展开更多
Following a half century of popularity, central place theory experienced 20 years of neglect when the new urban system theory of network modeling gained attention at the beginning of the 1990s. However, central place ...Following a half century of popularity, central place theory experienced 20 years of neglect when the new urban system theory of network modeling gained attention at the beginning of the 1990s. However, central place theory remains valid, and it seems there has been a reemergence with it. Using the Greater Pearl River Delta (Greater PRD) as an experimental study region, this paper intends to present an empirical study that validates central place theory and shows that it can be integrated into an overall regional urban system. The study uses the compound Central Place Importance (CPI) to evaluate whether there is a hierarchy among the urban centers within the study area. The results indicate the existence of a hierarchy. Furthermore, empirical observation finds distinct complementarity relationships, rank-size distributions, and co-operative actions between the different cities, thus substantiating the claim that central place theory can be incorporated into an overall regional urban system. Besides, the presence of the densely distributed modern infrastructure system also appears to constitute a dimension of the overall urban system. There need further theoretical and empirical studies in order to support this proposition.展开更多
Clarifying the mechanisms that control the evolution of territorial space patterns is essential for regulating and optimizing the geographical structure and processes related to sustainable development.Using the Guang...Clarifying the mechanisms that control the evolution of territorial space patterns is essential for regulating and optimizing the geographical structure and processes related to sustainable development.Using the Guangdong and Guangxi sections of the Pearl River Basin as examples,the transfer-matrix method and standard deviation ellipse model were applied to characterize the evolution of territorial space patterns from 1990 to 2020.A trend surface analysis and the Theil index were used to analyze regional differences in the evolution process,and geodetectors were used to identify the underlying mechanisms of the changes.There were three key results.(1)In these critical areas of the Pearl River Basin,agricultural and ecological spaces have rapidly declined due to urban expansion,with transfers between these spaces dominating the evolution of territorial space patterns.Spatial pattern changes in the Guangdong section were more intense than in the Guangxi section.(2)Regional differences in urban space have decreased,whereas differences in agricultural and ecological spaces have intensified.Driven by socio-economic growth,the cross-regional transfers of territorial space have created a“high in the east,while low in the west”inter-regional difference,and a“high in the south,while low in the north”intra-regional difference shaped by natural conditions.The regional differences in space patterns were greater in Guangdong than in Guangxi.(3)The evolution of watershed territorial space patterns resulted from scale changes,locational shifts,structural reorganizations,and directional changes driven by multiple factors.Natural environment,social life,economic development,and policy factors played foundational,leading,key driving,and guiding roles,respectively.Additionally,the regional differences in the evolution of watershed territorial space patterns originated from the differential transmission of the influence of various factors affecting spatial evolution.Enhancing urban space efficiency,restructuring agricultural space,and optimizing ecological space are key strategies for building a complementary and synergistic territorial space pattern in the basin.展开更多
文摘On the tranquil waters of Xiaoshanyang,a small lake in Deqing County,Zhejiang Province,rows of white,spherical buoys are lined up in perfect order,resembling strands of pearl necklaces.Once a thousand-year-old pearl-farming site,this heritage-rich waterbody has emerged as a global benchmark for the preservation of agricultural heritage.
文摘AIM:To summarize 10 surgical pearls for managing proliferative diabetic retinopathy(PDR)adapted from the ancient Chinese allusions and analyze the application of these pearls in a real-world fashion.METHODS:Retrospective,noncomparative,interventional study.Ten surgical pearls were summarized and adapted from the ancient Chinese philosophy.Totally 346 cases(443 eyes)that underwent pars plana vitrectomy(PPV)at our hospial from January 2016 to February 2024 were selected.Flexible combinations of these pearls were applied according to the specific condition of each patient during surgeries.The efficacy and safety were analyzed,as well as the application frequencies according to the existence of tractional retinal detachment or not.RESULTS:A total of 473 times of surgeries were performed on all the patients.According to ancient Chinese allusions,ten surgical pearls were summarized from these surgeries.All PPVs went smoothly with the application of different combinations.Finally,almost all proliferative membranes were successfully peeled except for 10 patients(11 eyes),who went through strategy No.10(minimal membranectomy)that,only necessary relaxation incisions were made with most of the proliferative membranes left on purpose.The final visual acuities were mostly improved or stable(1.92±0.83 LogMAR preoperatively vs 1.16±0.85 LogMAR postoperatively,P<0.01).Postoperative complications mainly included early inflammatory responses in the anterior chamber and nuclear sclerosis.Recurrent vitreous hemorrhage,retinal detachment,and hyphema or neovascular glaucoma occurred in 1.9%(9/473),3.2%(15/473),0.4%(2/473)and 0.4%(2/473)times of PPVs,respectively.After 12/473(2.5%)times of PPVs,retinal detachment at the macular area still existed,and multiple times of subsequent PPVs were conducted.Final retinal attachment at the macular area was realized in 98.9%eyes.Those 5 unattached eyes were with heavily reproliferated membranes and subsequent tractional retinal detachment recurrence under the oil,and three of them were scleral buckled additionally.CONCLUSION:These 10 surgical strategies and technique pearls were mostly effective and safe in the management of severe PDR patients.They were relatively easy to be memorized and applicated once the meaning of each Chinese idiom was understood.One can use different combinations flexibly according to a patient’s specific condition.
文摘Black tents,also known as black yak-wool tents due to their construction from yak wool,serve as the traditional accommodation for ethnic Tibetan nomads.From ancient times till now,these tents have long captured the nomadic life of herdsmen living on the Qinghai-Xizang Plateau.
基金Project supported by the Chinese Ministry of Education (205065)
文摘The transition of the superficial microstmcture of freshwater pearls induced by Ce was investigated by means of scanning electron microscopy. The pearls were cultured in freshwater containing 0 （control group ）, 0.5, 1, and 1.5 mg·L^-1 of a Ce additive. X-ray photoelectron spectroscopy （XPS） measurement showed that the concentration of Ce absorbed in the superficial microstmcture of pearls was positively correlated to the additive Ce. At the same time, the surface microstmcture of pearls changed greatly with Ce concentration, the shape of the blocks changed from spindly to perfect regular hexagonal sheets and finally to round discs. The glossiness of the pearls changed correspondingly with the microstmcture, pearls possessing the regular hexagonal blocks having the highest glossiness. Therefore, the REE Ce exerted a significant influence on the microstructure and glossiness of freshwater pearls. An appropriate quantity of Ce may improve the glossiness of pearls.
文摘Now, GISs are popular at most major cities along the coast in China. The lack of available digital geographic data is a serious bottleneck problem. This article first analyses the development characteristics of urban planning and management information system in China, and proposes a method for establishing a planning and management information system for small town. By using GIS as core and integrating with microcomputer network, office automation (OA), computer aided design (CAD), and multimedia technology, a microcomputer information system (TownMIS) is implemented after 3 year design and development. It may be a first comprehensive system for the planning and management of small towns. Since the January of 1996, TownMIS has been actually used in Xiaolan Town, a coastal rich town in South China. This has provided perfect technical, managerial, operational and institutional references for resolving the contradiction of the fast growing installation of GIS sites and fewer actually running system.
文摘The concept of urban green space system planning was proposed after analyzing the background of compiling Guangzhou green space system planning and current situation of local green spaces,i.e. design landscape pattern of Guangzhou City during urban agglomeration of the Pearl River Delta,and highlight Lingnan cultures(Lingnan refers to south of the Five Ridges) and features of "Flower City"(another name of Guangzhou). Key points of planning are protecting ecological barriers in the north,improving urban garden structure in the center,using wetland reasonably in the south,to maintain integrality and continuity of the landscape pattern.
文摘EDSS is a comprehensive software system for water quality management in tidal river networks in general and for the Pearl River Delta in particular. Its purpose is to provide a practical tool that could assist government agencies in decision making for the efficient management of water resources in terms of both quantity and quality. By combining the capabilities of geographical information system (GIS), database management system (DBMS), model base management system (MBMS) and expert system, the aim is to improve the quality of decision making in what is becoming an increasingly complex area. This paper first outlines the basic concepts and philosophy adopted in developing EDSS, the system architecture, design features, implementation techniques and facilities provided. Thereafter, the core part of the system—the hydrodynamic and water quality models are described briefly. The final contribution in this paper describes the application of EDSS to the Pearl River Delta, which has the most complicated tidal river network patterns as well as the fastest economic development in the world. Examples are given of the real-world problems that can be addressed using the system, including cross-boundary water pollution analysis, regional drinking water take-up site selection, screening of important polluters, environmental impact assessment, and water quality zoning and planning. It is illustrated that EDSS can provide efficient and scientific analytical tools for planning and decision-making purposes in the information era.
基金Under the auspices of National Natural Science Foundation of China (No.41171108)Knowledge Innovation Programs of Chinese Academy of Sciences (No.KZCXZ-YW-Q10-4-1)Project of National Science and Technology Infrastructure Program (No.2008BAH31B05)
文摘The growth of peripheral ports to dominant hubs has been well documented in North America and Europe,and has led to the elaboration of several theoretical models.However,although changes in containerization growth have been taking place in the South and East Asia in recent years,particularly in China,only a few studies have fo-cused on this region.The Pearl(Zhujiang) River Delta(PRD) has a typical port system with hub and peripheral ports,and provides an excellent case for studying the Peripheral Challenge.This paper introduces the theoretical evidence of the Hayuth model and analyzes the evolution of the container port system in the PRD with five phases:1) phase I:preconditions for change and phase II:initial container port development in the 1970s and early 1980s;2) phase III:diffusion,consolidation,and port concentration in the middle and late 1980s;3) phase IV:the load center in the 1990s;and(4) phase V:the Peripheral Challenge since the late 1990s.The results illustrate that the Shenzhen port presents mounting challenges to the Hong Kong port,descending from a transshipment hub of China to a regional load center of Southeast China.Furthermore,this paper explores five points that have led to the evolution of the port system in the PRD:1) competition in the regional port systems;2) different interested parties;3) shift of investment strategies of in-ternational terminal operators;4) integration of shipping networks and reorganization of carriers;and 5) cost-based competition.
基金Funded by the National Natural Science Foundation of China(No.20966002)
文摘Optical and micro-infrared microscope were used to observe the internal structure and mineral composition of high and low quality Chinese seawater and freshwater cultured pearls.Results clearly reveal that aragonite and calcite are found in seawater cultured pearls,but vaterite is not found.In contrast,vaterite and aragonite are found in freshwater cultured pearls,but calcite is not found.Based on our analysis and observations of the internal structure of high and low quality cultured pearls,a modified integrated model of the internal structure of Chinese cultured pearls was established.Our revisions to the previous model focus on significant differences within the prismatic layer of Chinese cultured pearls.
文摘AIM: To compare surgical peeling and aspiration and neodymium yttrium garnet laser capsulotomy for pearl form of posterior capsule opacification(PCO).METHODS: A prospective, randomized, double blind,study was done at Rotary Eye Hospital, Maranda,Palampur, India, Santosh Medical College Hospital,Ghaziabad, India and Laser Eye Clinic, Noida India.Consecutive patients with pearl form of PCO following surgery, phacoemulsification, manual small incision cataract surgery and conventional extracapsular cataract extraction(ECCE) for age related cataract, were randomized to have peeling and aspiration or neodymium yttrium garnet laser capsulotomy. Corrected distance visual acuity(CDVA), intra-operative and postoperative complications were compared.RESULTS: A total of 634 patients participated in the study, and 314(49.5%) patients were randomized to surgical peeling and aspiration group and 320(50.5%) to the Nd:YAG laser group. The mean pre-procedural log MAR CDVA in peeling and neodymium: yttrium-aluminium-garnet(Nd:YAG) laser group was 0.80 ±0.25 and 0.86 ±0.22, respectively. The mean final CDVA in peeling group(0.22 ±0.23) was comparable to Nd:YAG group(0.24 ±0.28; t-test, P =0.240). There was a significant improvement in vision after both the procedures(P 【0.001). A slightly higher percentage of patients in Nd:YAG laser group(283/88.3%) than in peeling group(262/83.4%) had a CDVA of 0.5(20/63) or better at 9mo(P 【0.001). On the contrary, patients havingCDVA worse than 1.00(20/200) was also significantly higher in Nd:YAG laser group as compared to peeling group(25/7.7% vs 15/4.7%, respectively). On application of ANCOVA, there was less than 0.001% risk that PCO thickness and total laser energy had no effect on rate of complications in Nd:YAG laser group and less than 0.001% risk that PCO thickness had no effect on complications in peeling group respectively. Sum of square analysis suggests that in the Nd:YAG laser group,thick PCO had a stronger impact on complications(Fischer test probability, P r 【0.0001) than thin PCO and total laser energy(Fischer test probability, P r 【0.002),respectively; similarly, in peeling group, thick PCO and preoperative vision had a stronger effect on complications than thin PCO, respectively(Fischer test probability, P r 【0.001). The rate of complications like uveitis(P =0.527) and cystoid macular edema(P =0.068),did not differ significantly between both the groups.However, intraocular pressure spikes(P =0.046) and retinal detachment(P【0.001) were significantly higher in Nd:YAG laser group as compared to peeling group.Retinal detachment was more common in patients having degenerative myopia(7/87.5%, P 【0.001). Recurrence of pearls was the most common cause of reduction of vision in the peeling group(24/7.6%, P 【0.001).CONCLUSION: There is no alternative to Nd:YAG laser capsulotomy for fibrous subtype of PCO. For pearl form of PCO, both techniques are comparable with regard to visual outcomes. Nd:YAG laser capsulotomy has a higher incidence of IOP spikes and retinal detachment whereas recurrence of pearls may occur after successful peeling and aspiration. When posterior capsulotomy is needed in patients with retinal degenerations,retinopathies and pre-existing retinal breaks, the clinician should be cautious about increased risks of possible complications of Nd:YAG laser capsulotomy.
基金The project supported by National Natural Science Foundation of China(NSFC)
文摘In this article we explored the crystal structure of a few pearls and shellfish's shell of fresh water and sea water, and found that pearls and nacreous layer (perhaps and prismatic layer) of shells are all the same: CaCO3, orthorhombic system, aragonite structure and the value of lattice spacings are almost identical. This shows that the pearls of fresh water and sea water are all the same in nature.
文摘A rhombic planform nonlinear cross-diffusive instability analysis is applied to a particular interaction-diffusion plant-ground water model system in an arid flat environment. This model contains a plant root suction effect as a cross-diffusion term in the ground water equation. In addition a threshold-dependent paradigm that differs from the usually employed implicit zero-threshold methodology is introduced to interpret stable rhombic patterns. These patterns are driven by root suction since the plant equation does not yield the required positive feedback necessary for the generation of standard Turing-type self-diffusive instabilities. The results of that analysis can be represented by plots in a root suction coefficient versus rainfall rate dimensionless parameter space. From those plots regions corresponding to bare ground and vegetative patterns consisting of isolated patches, rhombic arrays of pseudo spots or gaps separated by an intermediate rectangular state, and homogeneous distributions from low to high density may be identified in this parameter space. Then, a morphological sequence of stable vegetative states is produced upon traversing an experimentally-determined root suction characteristic curve as a function of rainfall through these regions. Finally, that predicted sequence along a rainfall gradient is compared with observational evidence relevant to the occurrence of leopard bush, pearled bush, or labyrinthine tiger bush vegetative patterns, used to motivate an aridity classification scheme, and placed in the context of some recent biological nonlinear pattern formation studies.
文摘Following a half century of popularity, central place theory experienced 20 years of neglect when the new urban system theory of network modeling gained attention at the beginning of the 1990s. However, central place theory remains valid, and it seems there has been a reemergence with it. Using the Greater Pearl River Delta (Greater PRD) as an experimental study region, this paper intends to present an empirical study that validates central place theory and shows that it can be integrated into an overall regional urban system. The study uses the compound Central Place Importance (CPI) to evaluate whether there is a hierarchy among the urban centers within the study area. The results indicate the existence of a hierarchy. Furthermore, empirical observation finds distinct complementarity relationships, rank-size distributions, and co-operative actions between the different cities, thus substantiating the claim that central place theory can be incorporated into an overall regional urban system. Besides, the presence of the densely distributed modern infrastructure system also appears to constitute a dimension of the overall urban system. There need further theoretical and empirical studies in order to support this proposition.
基金National Social Science Foundation Program,No.22VRC163National Natural Science Foundation of China,No.42061043+1 种基金Postgraduate Research&Practice Innovation Program of Jiangsu Province,No.KYCX24_1008Innovation Project of Guangxi Graduate Education,No.YCSW2024473。
文摘Clarifying the mechanisms that control the evolution of territorial space patterns is essential for regulating and optimizing the geographical structure and processes related to sustainable development.Using the Guangdong and Guangxi sections of the Pearl River Basin as examples,the transfer-matrix method and standard deviation ellipse model were applied to characterize the evolution of territorial space patterns from 1990 to 2020.A trend surface analysis and the Theil index were used to analyze regional differences in the evolution process,and geodetectors were used to identify the underlying mechanisms of the changes.There were three key results.(1)In these critical areas of the Pearl River Basin,agricultural and ecological spaces have rapidly declined due to urban expansion,with transfers between these spaces dominating the evolution of territorial space patterns.Spatial pattern changes in the Guangdong section were more intense than in the Guangxi section.(2)Regional differences in urban space have decreased,whereas differences in agricultural and ecological spaces have intensified.Driven by socio-economic growth,the cross-regional transfers of territorial space have created a“high in the east,while low in the west”inter-regional difference,and a“high in the south,while low in the north”intra-regional difference shaped by natural conditions.The regional differences in space patterns were greater in Guangdong than in Guangxi.(3)The evolution of watershed territorial space patterns resulted from scale changes,locational shifts,structural reorganizations,and directional changes driven by multiple factors.Natural environment,social life,economic development,and policy factors played foundational,leading,key driving,and guiding roles,respectively.Additionally,the regional differences in the evolution of watershed territorial space patterns originated from the differential transmission of the influence of various factors affecting spatial evolution.Enhancing urban space efficiency,restructuring agricultural space,and optimizing ecological space are key strategies for building a complementary and synergistic territorial space pattern in the basin.
