Objective:To evaluate the effectiveness of the internal limiting membrane(ILM)flipping and covering technique in the treatment of patients with high myopic macular hole(HMMH).Methods:One hundred and two patients with ...Objective:To evaluate the effectiveness of the internal limiting membrane(ILM)flipping and covering technique in the treatment of patients with high myopic macular hole(HMMH).Methods:One hundred and two patients with HMMH who were admitted to the hospital from June 2019 to June 2024 were selected.The minimum diameter of the macular hole(MH)in all patients was≤500μm.The patients were randomly divided into two groups.The experimental group received 25G pars plana vitrectomy(PPV)combined with ILM flipping and covering technique,while the reference group received PPV combined with ILM peeling.The efficacy indicators and best corrected visual acuity levels were compared between the two groups.Results:The MH closure rate and retinal reattachment rate were higher in the experimental group than in the reference group at 3 and 6 months postoperatively(P<0.05).The best corrected visual acuity level was higher in the experimental group than in the reference group at 3 and 6 months postoperatively(P<0.05).The Chinese version of the Visual Function-Related Quality of Life Questionnaire-25(CVRQOL-25)score was higher in the experimental group than in the reference group at 3 and 6 months postoperatively(P<0.05).No serious complications were observed in both groups postoperatively,and there was no difference between the two groups(P>0.05).Conclusion:The ILM flipping and covering technique can improve the MH closure rate and retinal reattachment rate in patients with HMMH(diameter≤500μm),enhance the best corrected visual acuity level,and improve the quality of life related to visual function,with fewer postoperative complications.展开更多
Agricultural land development is a pivotal strategy for addressing the global food security crisis.Barren grassland,especially those in mountainous regions,constitutes critical areas where cultivation can substantiall...Agricultural land development is a pivotal strategy for addressing the global food security crisis.Barren grassland,especially those in mountainous regions,constitutes critical areas where cultivation can substantially enhance land resources.This study highlights the necessity for a precise correlation between land development initiatives and constraints in order to optimize efficiency and enhance the effectiveness of such projects,with the core being the seamless integration of land development engineering and techniques to eliminate agricultural constraints.This study employs a systems engineering approach to classify improvement factors into mobile and fixed categories,elucidating the integration methods of constraint factors.Adhering to the Wooden Barrel Principle,these constraints were rigorously analyzed based on soil quality,land topography,water availability,and agricultural infrastructure.An innovative method of engineering type combination is proposed,which effectively explains the correlation between natural factors combination,project type combination,and target factors combination.It provides a convenient way for the selection of barren grassland development projects and lays a foundation for land planning,development project establishment,program selection,engineering design,and budget preparation.Taking Tang County of China as an example,it is divided into 19 factor improvement areas,a quick reference table of engineering types is established,and 14 main types of engineering combinations are obtained,which lays a foundation for the application of theoretical framework in practice.展开更多
AIM:To evaluate the surgical outcomes of the perfluorocarbon liquid(PFCL)-assisted inverted multilayer internal limiting membrane(ILM)flaps covering technique in macular hole retinal detachment(MHRD)in high myopia wit...AIM:To evaluate the surgical outcomes of the perfluorocarbon liquid(PFCL)-assisted inverted multilayer internal limiting membrane(ILM)flaps covering technique in macular hole retinal detachment(MHRD)in high myopia with axial length(AL)≥30 mm.METHODS:In this retrospective,interventional,consecutive comparative study,44 MHRD eyes were divided into two groups:the PFCL-assisted inverted multilayer ILM flaps covering technique group(Group 1,21 eyes)and the ILM peeling group(Group 2,23 eyes).The follow-up period was>12mo.Postoperative outcomes,including retinal reattachment,macular hole(MH)closure,and bestcorrected visual acuity(BCVA),were assessed.Statistical analysis using the Mann–Whitney U test and Fisher’s exact test was conducted to compare differences between groups.RESULTS:There were no statistically significant differences in baseline preoperative clinical characteristics,including age,sex,AL,diopters,duration of symptom,lens status,posterior staphyloma presence and extent of RD.Retinal reattachment rates were higher in Group 1(90.5%)than in Group 2(82.6%),without statistical significance(P=0.667).MH closure rates were significantly higher in Group 1(85.7%)than in Group 2(17.4%;P<0.001).The Group-1 BCVA(logMAR)improved significantly from 2.13±0.91 preoperatively to 1.21±0.66 postoperatively(P=0.026).The Group 2 BCVA improved significantly from 1.91±0.53 preoperatively to 1.19±0.41 postoperatively(P=0.032).However,there were no significant differences in visual-acuity improvement between groups(P=0.460).CONCLUSION:This technique offers a more effective approach for improving MH closure rates and postoperative visual function in MHRD with AL≥30 mm in high myopia.展开更多
As a new dynamic reactive power compensator,the grid-forming Static Var Generator(GF-SVG)can not only provide reactive power-voltage support,but also has inertial support capability.It has been experimentally deployed...As a new dynamic reactive power compensator,the grid-forming Static Var Generator(GF-SVG)can not only provide reactive power-voltage support,but also has inertial support capability.It has been experimentally deployed in many wind farms.However,studies have shown that when the three-phase short-circuit fault occurs in the wind farm,the transient overcurrent during the fault occurrence and fault clearance is suppressed,making it difficult for GF-SVG to use traditional fixed virtual impedance.Aiming at the problem,firstly,the influence of virtual reactance on control stability is analyzed using the GF-SVG’s current open-loop transfer function.Secondly,based on the existing current limitation strategies of GF-SVG,an adaptive virtual reactance current limitation strategy suitable for symmetrical faults of the power grid is proposed,which limits GF-SVG’s transient overcurrent during fault occurrence and fault clearance stage to the tolerance range of GF-SVG’s power devices.Based on the GF-SVG’s active power loop and reactive power loop small signal models,the availability of the proposed adaptive virtual reactance in suppressing the DC voltage drop of GF-SVG is analyzed,and shortening the transient overvoltage recovery time of the wind farm after the fault clearance is also discussed.Finally,electromagnetic simulation proves the effectiveness and correctness of the proposed adaptive current limitation method.展开更多
We extend the monolithic convex limiting(MCL)methodology to nodal discontinuous Galerkin spectral-element methods(DGSEMS).The use of Legendre-Gauss-Lobatto(LGL)quadrature endows collocated DGSEM space discretizations ...We extend the monolithic convex limiting(MCL)methodology to nodal discontinuous Galerkin spectral-element methods(DGSEMS).The use of Legendre-Gauss-Lobatto(LGL)quadrature endows collocated DGSEM space discretizations of nonlinear hyperbolic problems with properties that greatly simplify the design of invariant domain-preserving high-resolution schemes.Compared to many other continuous and discontinuous Galerkin method variants,a particular advantage of the LGL spectral operator is the availability of a natural decomposition into a compatible subcellflux discretization.Representing a highorder spatial semi-discretization in terms of intermediate states,we performflux limiting in a manner that keeps these states and the results of Runge-Kutta stages in convex invariant domains.In addition,local bounds may be imposed on scalar quantities of interest.In contrast to limiting approaches based on predictor-corrector algorithms,our MCL procedure for LGL-DGSEM yields nonlinearflux approximations that are independent of the time-step size and can be further modified to enforce entropy stability.To demonstrate the robustness of MCL/DGSEM schemes for the compressible Euler equations,we run simulations for challenging setups featuring strong shocks,steep density gradients,and vortex dominatedflows.展开更多
Assume that f is a transcendental entire function.The ray arg z=θ∈[0,2π]is said to be a limiting direction of the Julia set J(f)of f if there exists an unbounded sequence{z_(n)}■J(f)such that lim rn→∞ arg z_(n)=...Assume that f is a transcendental entire function.The ray arg z=θ∈[0,2π]is said to be a limiting direction of the Julia set J(f)of f if there exists an unbounded sequence{z_(n)}■J(f)such that lim rn→∞ arg z_(n)=θ.In this paper,we mainly investigate the dynamical properties of Julia sets of entire solutions of the complex differential equations F(z)f^(n)(z)+P(z,f)=0,and f^(n)+A(z)P(z,f)=h(z),where P(z,f)is a differential polynomial in f and its derivatives,F(z),A(z)and h(z)are entire functions.We demonstrate the existence of close relationships Petrenko's deviations of the coefficients and the measures of limiting directions of entire solutions of the above two equations.展开更多
Shock waves,characterized by abrupt changes in pressure,temperature,and density,play a significant role in various materials science processes involving fluids.These high-energy phenomena are utilized across multiple ...Shock waves,characterized by abrupt changes in pressure,temperature,and density,play a significant role in various materials science processes involving fluids.These high-energy phenomena are utilized across multiple fields and applications to achieve unique material properties and facilitate advanced manufacturing techniques.Accurate simulations of these phenomena require numerical schemes that can represent shock waves without spurious oscillations and simultaneously capture acoustic waves for a wide range of wavelength scales.This work suggests a high-order discontinuous Galerkin(DG)method with a finite volume(FV)subcell limiting strategies to achieve better subcell resolution and lower numerical diffusion properties.By switching to the FV discretization on an embedded sub-cell grid,the method displays advantages with respect to both DG accuracy and FV shock-capturing ability.The FV scheme utilizes a class of high-fidelity schemes that are built upon the boundary variation diminishing(BVD)reconstruction paradigm.The method is therefore able to resolve discontinuities and multi-scale structures on the subcell level,while preserving the favorable properties of the high-order DG scheme.We have tested the present DG method up to the 6th-order accuracy for both smooth and discontinuous noise problems.展开更多
AIM:To compare the efficacy of pars plana vitrectomy(PPV)combined with internal limiting membrane(ILM)and silicone oil or sterile air tamponade for the treatment of myopic foveoschisis(MF)in highly myopic eyes.METHODS...AIM:To compare the efficacy of pars plana vitrectomy(PPV)combined with internal limiting membrane(ILM)and silicone oil or sterile air tamponade for the treatment of myopic foveoschisis(MF)in highly myopic eyes.METHODS:This retrospective study included 48 myopic eyes of 40 patients with MF and axial lengths(ALs)ranging from 26-32 mm treated between January 2020 and January 2022.All patients were underwent PPV combined with ILM peeling followed by sterile air or silicone oil tamponade and followed up at least 12mo.Based on the features on spectral-domain optical coherence tomography(SD-OCT),the eyes were divided into the MF-only group(Group A,n=15 eyes),MF with central foveal detachment group(Group B,n=20 eyes),and MF with lamellar macular hole group(Group C,n=13 eyes).According to AL,eyes were further divided into three groups:Group D(26.01-28.00 mm,n=12 eyes),Group E(28.01-30.00 mm,n=26 eyes),and Group F(30.01-32.00 mm,n=10 eyes).The best-corrected visual acuity(BCVA),central foveal thickness(CFT),and complications were recorded.RESULTS:The patients included 16 males and 24 females with the mean age of 56±9.82y.The BCVA and CFT improved in all groups after surgery(P<0.01),while there was no significant difference of the CFT in Group A,B,and C postoperatively(P>0.05).The intergroup differences of BCVA and CFT postoperatively were statistically significant in Group D,E,and F.Twenty eyes were injected with sterile air,and 28 eyes were injected with silicone oil for tamponade based on the AL.However,there was no statistically significant difference among Groups D,E,and F in terms of the results of sterile air or silicone oil tamponade.The mean recovery time was 5.9mo for MF patients subjected to silicone oil tamponade and 7.7mo for patients subjected to sterile air tamponade,and the difference was not statistically significant.CONCLUSION:PPV and ILM peeling combined with silicone oil or sterile air tamponade can achieve good results for MF in highly myopic eyes with ALs≤32 mm.展开更多
BACKGROUND Diabetic macular edema(DME),a chronic microvascular complication of diabetes,is a leading cause of visual impairment and blindness.Pars plana vitrectomy(PPV)can restore the normal macular structure and redu...BACKGROUND Diabetic macular edema(DME),a chronic microvascular complication of diabetes,is a leading cause of visual impairment and blindness.Pars plana vitrectomy(PPV)can restore the normal macular structure and reduce macular edema,whereas internal limiting membrane(ILM)peeling is used to treat tractional macular diseases.Despite the advantages,there is limited research on the combined effects of PPV with ILM peeling.AIM To observe the effects of PPV combined with ILM peeling on postoperative central macular thickness(CMT),best-corrected visual acuity(BCVA),cystoid macular edema(CME)volume,and complications in patients with DME.METHODS Eighty-one patients(92 eyes)diagnosed with DME at the Beijing Shanqu Liangxiang Hospital between January and December 2022 were randomly divided to undergo PPV alone(control group:41 patients,47 eyes)or PPV+ILM peeling(stripping group:40 patients,45 eyes);a single surgeon performed all surgeries.The two groups were compared preoperatively and 1 and 3 months postoperatively.RESULTS Preoperatively,both groups had comparable values of CMT,BCVA,and CME volume(P>0.05).After surgery(both 1 and 3 months),both groups showed significant reductions in CMT,BCVA,and CME volume compared to preoperative levels,with the stripping group showing more significant reductions compared to the control group(P<0.05).Further repeated-measures ANOVA analysis for within-group differences revealed significant effects of group and time,and interaction effects for CMT,BCVA,and CME volume(P<0.05).There were no significant differences in the incidence of complications between the groups(retinal detachment:control=2,stripping=1;endophthalmitis:Control=4,stripping=1;no cases of secondary glaucoma or macular holes;χ^(2)=0.296,P=0.587).CONCLUSION PPV with ILM peeling can significantly improve the visual acuity of patients with DME,reduce CMT,and improve CME with fewer complications.展开更多
[Objective] This study aimed to provide basis for rational fertilizer application of wheat in fluvo-aquic soil in the northwest of Shandong Province.[Method] In this paper,the treatments of reduced N,P and K were set ...[Objective] This study aimed to provide basis for rational fertilizer application of wheat in fluvo-aquic soil in the northwest of Shandong Province.[Method] In this paper,the treatments of reduced N,P and K were set in order to explore the effects of fertilizer recommendation based on ASI systematic approach on wheat yield,agronomic efficiency and recovery rate of nutrients.[Result] Nitrogen was the main limiting factor for wheat production in that area,followed by phosphorus,and the third was potassium.Compared with the optimum treatment （OPT）,the reduction of N,P and K reduced the grain yield obviously,which came up to 22.4％,14.4％ and 13.4％ respectively.There were no obvious differences in grain yield among Farmer＇s Fertilization Practice （FP）,60％ OPT-N and OPT treatment.[Conclusion] Agronomic efficiency of N,P and K was 6.3,12.9 and 10 kg/kg respectively.The recovery rates of N,P and K in wheat season were 16.41％,17.27％ and 27.27％ respectively.展开更多
A 12 Gbit/s limiting amplifier for fiber-optic transmission system is realized in a 2μm GaAs HBT technology. The whole circuit consists of an input buffer, three similar amplifier cells, an output buffer for driving ...A 12 Gbit/s limiting amplifier for fiber-optic transmission system is realized in a 2μm GaAs HBT technology. The whole circuit consists of an input buffer, three similar amplifier cells, an output buffer for driving 50 ft transmission lines and a pair of feedback networks for offset cancellation. At a positive supply voltage of 2 V and a negative supply voltage of - 2V, the power dissipation is about 280 mW. The small-signal gain is higher than 46 dB and the input dynamic range is about 40 dB with a constant single-ended output voltage swing of 400 mV. Satisfactory eye-diagrams are obtained at the bit rate of 12 Gbit/s limited by the test set-up. The chip area is 1.15 mm ×0.7 mm.展开更多
Three goats fitted with cannula were used to provide rumen liquor to investigate the effects of limiting amino acids on rumen fermentation and microbial community in vitro. The removal method was used in the current e...Three goats fitted with cannula were used to provide rumen liquor to investigate the effects of limiting amino acids on rumen fermentation and microbial community in vitro. The removal method was used in the current experiments. Treatments are total essential amino acid （TEAA）, His-removal, Lys-removal, Met-removal, and branch chain amino acid （BCAA）- removal. Results indicated that, pH-value ranged between 5.9 and 6.8, with the highest mean value for the group with BCAA-removal （6.54） in the culture. Concentration of NH3-N ranged between 10.99 to 30.51 mg 100 mL^-1, with the group of TEAA recording the highest average NH3-N concentration （17.85 mg 100 mL^-1）. Yields of microbial protein and limiting degree on microbial growth varied with treatments （P 〈 0.01）, and the lowest accrued in treatment with BCAA-removal （0.1389, 0.1772, and 0.3161 mg mL^-1 for bacteria, protozoa, and mixed microbes, respectively）, compared to the group with TEAA, microbial production of mixed microbes decreased by 44.52%. As for micro-flora, protozoa to bacteria ratio was the lowest for the group with Lys-removal （89.12%）, while the highest for the group with BCAA-removal （127.60%） （P 〈 0.01）. Furthermore, PCR-SSCP analysis revealed that, microbial profile subjected to substrates within bacteria and protozoa groups. It was therefore concluded that, dietary amino acid influenced both rumen fermentation and microbial characteristics.展开更多
Vitrectomy combined with internal limiting membrane(ILM)peeling is popular for the treatment of macular hole(MH).However,the improvements of MH closure rate and postoperative visual acuity are not satisfactory especia...Vitrectomy combined with internal limiting membrane(ILM)peeling is popular for the treatment of macular hole(MH).However,the improvements of MH closure rate and postoperative visual acuity are not satisfactory especially in large and refractory MHs.Currently,the ILM flap technique has gradually been applied for the treatment of MH and achieved high MH closure rate.The ILM flap technique has many variations,including the difference of the size,shape,number,and manner in which the flaps put on the MHs.The ILM flap technique also has some auxiliary means including perfluoro-n-octane(PFO),dye,autologous blood and adhesive viscoelastics.There is controversy about the effects between several technique variations of ILM flap,and it needs to be explored in the future.展开更多
WT8.BZ]A new quasi 2-dimensional analytical approach to predicting the ring voltage,edge peak fields and optimal spacing of the planar junction with a single floating field limiting ring structure has been proposed,ba...WT8.BZ]A new quasi 2-dimensional analytical approach to predicting the ring voltage,edge peak fields and optimal spacing of the planar junction with a single floating field limiting ring structure has been proposed,based on the cylindrical symmetric solution and the critical field concept.The effects of the spacing and reverse voltage on the ring junction voltage and edge peak field profiles have been analyzed.The optimal spacing and the maximum breakdown voltage of the structure have also been obtained.The analytical results are in excellent agreement with that obtained from the 2-D device simulator,MEDICI and the reported result,which proves the presented model valid.展开更多
A limiting amplifier (LA) IC implemented in TSMC standard 0.25μm CMOS technology is described.Active inductor loads and direct-coupled technology are employed to increase the gain,broaden the bandwidth,reduce the pow...A limiting amplifier (LA) IC implemented in TSMC standard 0.25μm CMOS technology is described.Active inductor loads and direct-coupled technology are employed to increase the gain,broaden the bandwidth,reduce the power dissipation,and keep a tolerable noise performance.Under a 3.3V supply voltage,the LA core achieves a gain of 50-dB with a power consumption below 40mW.The measured input sensitivity of the amplifier is better than 5m V _ pp .It can operate at bit rates up to 7Gb/s with an rms jitter of 0.03 UI or less.The chip area is only 0.70mm×0.70mm.According to the measurement results,this IC is expected to work at the standard bit rate levels of 2.5,3.125,and 5Gb/s.展开更多
A vertical sandwich deep trench with a field limiting ring is proposed to improve the breakdown voltage of power devices and high voltage devices.Simulation result shows that nearly 100% breakdown voltage of the plane...A vertical sandwich deep trench with a field limiting ring is proposed to improve the breakdown voltage of power devices and high voltage devices.Simulation result shows that nearly 100% breakdown voltage of the plane junction can be realized.展开更多
This paper presents a 155Mbps limiting amplifier for STM-1 systems of SDH optical communication. It is implemented in CSMC 0.5μm CMOS technology. Under a supply voltage of 3.3V, it has a power consumption of 198mW. T...This paper presents a 155Mbps limiting amplifier for STM-1 systems of SDH optical communication. It is implemented in CSMC 0.5μm CMOS technology. Under a supply voltage of 3.3V, it has a power consumption of 198mW. The core of the circuit is composed of 6 cascaded amplifiers that are in a conventional structure of differential pairs,an output buffer, and a DC offset cancellation feedback loop. The small signal gain can be adjusted from 74 to 44dB by an off-chip resistor. The chip was packaged before being tested. The experimental results indicate that the circuit has an input dynamic range of 54dB and provides a single-ended output swing of 950mV. Its output eye diagram remains satisfactory when the pseudo-random bit sequence （PRBS） input speed reaches 400Mbps.展开更多
[Objective] This paper aimed to understand the area change and distribu- tion of medium-low yield farmland, and offered basis to the improvement of mediumlow farmland and its increase of grain production in Tianjin. [...[Objective] This paper aimed to understand the area change and distribu- tion of medium-low yield farmland, and offered basis to the improvement of mediumlow farmland and its increase of grain production in Tianjin. [Method] Based on the statistical date of Tianjin and its relevant counties and districts, the yield standard was set up to classify high-yield, medium-yield and low-yield farmland in Tianjin. The author analyzed area change of medium-low yield farmland in six agricultural counties and districts （including Jixian County, Wuqing District, Baodi District, Ninghe County, Jinghai County and Dagang district of Binghai New Area） from 1980 to 2010. [Result] The results showed that the average yield of grain rose from 2 445 kg/hm^2 in 1980 to 5 130 kg/hm^2 in 2010, increasing 109.82%. The area of mediumlow yield farmland was reduced from 291 250.13 hm^2 in 1985 to 76 489.87 hm^2 in 2010, coming down 74%. In Tianjin, the area of medium-low yield farmland of 2010 accounted for 19% of the total farmland, of which the ratios of medium-low yield farmland of Jinghai County, Jixian County, Dagang district of Binghai New Area, Wuqing District, Baodi District and Ninghe County were 43.12%, 18.59%, 17.23%, 14.01%, 7.05% and 0, respectively. Low soil nutrient content, drought and water shortage, as well as soil salinization were the main yield limiting factors to mediumlow yield farmland in Tianjin in 2010. [Conclusion] The countermeasures to improve the medium-low yield farmland were proposed, involving enhancing the investment of the government, strengthening the construction of water conservancy infrastructure, further improving the soil fertility, as well as saline and alkaline land, optimizing the farming system and planting drought and salt tolerance crops, etc.展开更多
Due to the low impedance characteristic of the high voltage direct current(HVDC)grid,the fault current rises extremely fast after a DC-side fault occurs,and this phenomenon seriously endangers the safety of the HVDC g...Due to the low impedance characteristic of the high voltage direct current(HVDC)grid,the fault current rises extremely fast after a DC-side fault occurs,and this phenomenon seriously endangers the safety of the HVDC grid.In order to suppress the rising speed of the fault current and reduce the current interruption requirements of the main breaker(MB),a fault current limiting hybrid DC circuit breaker(FCL-HCB)has been proposed in this paper,and it has the capability of bidirectional fault current limiting and fault current interruption.After the occurrence of the overcurrent in the HVDC grid,the current limiting circuit(CLC)of FCL-HCB is put into operation immediately,and whether the protected line is cut off or resumed to normal operation is decided according to the fault detection result.Compared with the traditional hybrid DC circuit breaker(HCB),the required number of semiconductor switches and the peak value of fault current after fault occurs are greatly reduced by adopting the proposed device.Extensive simulations also verify the effectiveness of the proposed FCL-HCB.展开更多
Jiaozhou Bay data collected from May 1991 to February 1994, in 12 seasonal investigations, and provided the authors by the Ecological Station of Jiaozhou Bay, were analyzed to determine the spatiotemporal variations i...Jiaozhou Bay data collected from May 1991 to February 1994, in 12 seasonal investigations, and provided the authors by the Ecological Station of Jiaozhou Bay, were analyzed to determine the spatiotemporal variations in temperature, light, nutrients (NO - 3 N, NO - 2 N, NH + 4 N, SiO 2- 3 Si, PO 3- 4 P), phytoplankton, and primary production in Jiaozhou Bay. The results indicated that only silicate correlated well in time and space with, and had important effects on, the characteristics, dynamic cycles and trends of, primary production in Jiaozhou Bay. The authors developed a corresponding dynamic model of primary production and silicate and water temperature. Eq.(1) of the model shows that the primary production variation is controlled by the nutrient Si and affected by water temperature; that the main factor controlling the primary production is Si; that water temperature affects the composition of the structure of phytoplankton assemblage; that the different populations of the phytoplankton assemblage occupy different ecological niches for C , the apparent ratio of conversion of silicate in seawater into phytoplankton biomas and D , the coefficient of water temperature’s effect on phytoplankton biomass. The authors researched the silicon source of Jiaozhou Bay, the biogeochemical sediment process of the silicon, the phytoplankton predominant species and the phytoplankton structure. The authors considered silicate a limiting factor of primary production in Jiaozhou Bay, whose decreasing concentration of silicate from terrestrial source is supposedly due to dilution by current and uptake by phytoplankton; quantified the silicate assimilated by phytoplankton, the intrinsic ratio of conversion of silicon into phytoplankton biomass, the proportion of silicate uptaken by phytoplankton and diluted by current; and found that the primary production of the phytoplankton is determined by the quantity of the silicate assimilated by them. The phenomenon of apparently high plant nutrient concentrations but low phytoplankton biomass in some waters is reasonably explained in this paper.展开更多
文摘Objective:To evaluate the effectiveness of the internal limiting membrane(ILM)flipping and covering technique in the treatment of patients with high myopic macular hole(HMMH).Methods:One hundred and two patients with HMMH who were admitted to the hospital from June 2019 to June 2024 were selected.The minimum diameter of the macular hole(MH)in all patients was≤500μm.The patients were randomly divided into two groups.The experimental group received 25G pars plana vitrectomy(PPV)combined with ILM flipping and covering technique,while the reference group received PPV combined with ILM peeling.The efficacy indicators and best corrected visual acuity levels were compared between the two groups.Results:The MH closure rate and retinal reattachment rate were higher in the experimental group than in the reference group at 3 and 6 months postoperatively(P<0.05).The best corrected visual acuity level was higher in the experimental group than in the reference group at 3 and 6 months postoperatively(P<0.05).The Chinese version of the Visual Function-Related Quality of Life Questionnaire-25(CVRQOL-25)score was higher in the experimental group than in the reference group at 3 and 6 months postoperatively(P<0.05).No serious complications were observed in both groups postoperatively,and there was no difference between the two groups(P>0.05).Conclusion:The ILM flipping and covering technique can improve the MH closure rate and retinal reattachment rate in patients with HMMH(diameter≤500μm),enhance the best corrected visual acuity level,and improve the quality of life related to visual function,with fewer postoperative complications.
基金funded by Science and Technology Project of Hebei Education Department[QN2023085].
文摘Agricultural land development is a pivotal strategy for addressing the global food security crisis.Barren grassland,especially those in mountainous regions,constitutes critical areas where cultivation can substantially enhance land resources.This study highlights the necessity for a precise correlation between land development initiatives and constraints in order to optimize efficiency and enhance the effectiveness of such projects,with the core being the seamless integration of land development engineering and techniques to eliminate agricultural constraints.This study employs a systems engineering approach to classify improvement factors into mobile and fixed categories,elucidating the integration methods of constraint factors.Adhering to the Wooden Barrel Principle,these constraints were rigorously analyzed based on soil quality,land topography,water availability,and agricultural infrastructure.An innovative method of engineering type combination is proposed,which effectively explains the correlation between natural factors combination,project type combination,and target factors combination.It provides a convenient way for the selection of barren grassland development projects and lays a foundation for land planning,development project establishment,program selection,engineering design,and budget preparation.Taking Tang County of China as an example,it is divided into 19 factor improvement areas,a quick reference table of engineering types is established,and 14 main types of engineering combinations are obtained,which lays a foundation for the application of theoretical framework in practice.
基金Supported by Research Incubation Fund of Xi’an People’s Hospital(Xi’an Fourth Hospital)(No.FZ-58).
文摘AIM:To evaluate the surgical outcomes of the perfluorocarbon liquid(PFCL)-assisted inverted multilayer internal limiting membrane(ILM)flaps covering technique in macular hole retinal detachment(MHRD)in high myopia with axial length(AL)≥30 mm.METHODS:In this retrospective,interventional,consecutive comparative study,44 MHRD eyes were divided into two groups:the PFCL-assisted inverted multilayer ILM flaps covering technique group(Group 1,21 eyes)and the ILM peeling group(Group 2,23 eyes).The follow-up period was>12mo.Postoperative outcomes,including retinal reattachment,macular hole(MH)closure,and bestcorrected visual acuity(BCVA),were assessed.Statistical analysis using the Mann–Whitney U test and Fisher’s exact test was conducted to compare differences between groups.RESULTS:There were no statistically significant differences in baseline preoperative clinical characteristics,including age,sex,AL,diopters,duration of symptom,lens status,posterior staphyloma presence and extent of RD.Retinal reattachment rates were higher in Group 1(90.5%)than in Group 2(82.6%),without statistical significance(P=0.667).MH closure rates were significantly higher in Group 1(85.7%)than in Group 2(17.4%;P<0.001).The Group-1 BCVA(logMAR)improved significantly from 2.13±0.91 preoperatively to 1.21±0.66 postoperatively(P=0.026).The Group 2 BCVA improved significantly from 1.91±0.53 preoperatively to 1.19±0.41 postoperatively(P=0.032).However,there were no significant differences in visual-acuity improvement between groups(P=0.460).CONCLUSION:This technique offers a more effective approach for improving MH closure rates and postoperative visual function in MHRD with AL≥30 mm in high myopia.
基金supported by the National Natural Science Foundation of China under Grant 52077030.
文摘As a new dynamic reactive power compensator,the grid-forming Static Var Generator(GF-SVG)can not only provide reactive power-voltage support,but also has inertial support capability.It has been experimentally deployed in many wind farms.However,studies have shown that when the three-phase short-circuit fault occurs in the wind farm,the transient overcurrent during the fault occurrence and fault clearance is suppressed,making it difficult for GF-SVG to use traditional fixed virtual impedance.Aiming at the problem,firstly,the influence of virtual reactance on control stability is analyzed using the GF-SVG’s current open-loop transfer function.Secondly,based on the existing current limitation strategies of GF-SVG,an adaptive virtual reactance current limitation strategy suitable for symmetrical faults of the power grid is proposed,which limits GF-SVG’s transient overcurrent during fault occurrence and fault clearance stage to the tolerance range of GF-SVG’s power devices.Based on the GF-SVG’s active power loop and reactive power loop small signal models,the availability of the proposed adaptive virtual reactance in suppressing the DC voltage drop of GF-SVG is analyzed,and shortening the transient overvoltage recovery time of the wind farm after the fault clearance is also discussed.Finally,electromagnetic simulation proves the effectiveness and correctness of the proposed adaptive current limitation method.
文摘We extend the monolithic convex limiting(MCL)methodology to nodal discontinuous Galerkin spectral-element methods(DGSEMS).The use of Legendre-Gauss-Lobatto(LGL)quadrature endows collocated DGSEM space discretizations of nonlinear hyperbolic problems with properties that greatly simplify the design of invariant domain-preserving high-resolution schemes.Compared to many other continuous and discontinuous Galerkin method variants,a particular advantage of the LGL spectral operator is the availability of a natural decomposition into a compatible subcellflux discretization.Representing a highorder spatial semi-discretization in terms of intermediate states,we performflux limiting in a manner that keeps these states and the results of Runge-Kutta stages in convex invariant domains.In addition,local bounds may be imposed on scalar quantities of interest.In contrast to limiting approaches based on predictor-corrector algorithms,our MCL procedure for LGL-DGSEM yields nonlinearflux approximations that are independent of the time-step size and can be further modified to enforce entropy stability.To demonstrate the robustness of MCL/DGSEM schemes for the compressible Euler equations,we run simulations for challenging setups featuring strong shocks,steep density gradients,and vortex dominatedflows.
基金Supported by the National Natural Science Foundation of China(11971344)。
文摘Assume that f is a transcendental entire function.The ray arg z=θ∈[0,2π]is said to be a limiting direction of the Julia set J(f)of f if there exists an unbounded sequence{z_(n)}■J(f)such that lim rn→∞ arg z_(n)=θ.In this paper,we mainly investigate the dynamical properties of Julia sets of entire solutions of the complex differential equations F(z)f^(n)(z)+P(z,f)=0,and f^(n)+A(z)P(z,f)=h(z),where P(z,f)is a differential polynomial in f and its derivatives,F(z),A(z)and h(z)are entire functions.We demonstrate the existence of close relationships Petrenko's deviations of the coefficients and the measures of limiting directions of entire solutions of the above two equations.
基金supported by the National Natural Science Foundation of China under Grant Nos.92252201 and 11721202support by the Laboratory of Aerodynamic Noise Control under Grant No.2301ANCL20230303 and the Fundamental Research Funds for the Central Universities.
文摘Shock waves,characterized by abrupt changes in pressure,temperature,and density,play a significant role in various materials science processes involving fluids.These high-energy phenomena are utilized across multiple fields and applications to achieve unique material properties and facilitate advanced manufacturing techniques.Accurate simulations of these phenomena require numerical schemes that can represent shock waves without spurious oscillations and simultaneously capture acoustic waves for a wide range of wavelength scales.This work suggests a high-order discontinuous Galerkin(DG)method with a finite volume(FV)subcell limiting strategies to achieve better subcell resolution and lower numerical diffusion properties.By switching to the FV discretization on an embedded sub-cell grid,the method displays advantages with respect to both DG accuracy and FV shock-capturing ability.The FV scheme utilizes a class of high-fidelity schemes that are built upon the boundary variation diminishing(BVD)reconstruction paradigm.The method is therefore able to resolve discontinuities and multi-scale structures on the subcell level,while preserving the favorable properties of the high-order DG scheme.We have tested the present DG method up to the 6th-order accuracy for both smooth and discontinuous noise problems.
基金Supported by the Natural Science Basic Research Program in Shaanxi Province(No.2020JM-683).
文摘AIM:To compare the efficacy of pars plana vitrectomy(PPV)combined with internal limiting membrane(ILM)and silicone oil or sterile air tamponade for the treatment of myopic foveoschisis(MF)in highly myopic eyes.METHODS:This retrospective study included 48 myopic eyes of 40 patients with MF and axial lengths(ALs)ranging from 26-32 mm treated between January 2020 and January 2022.All patients were underwent PPV combined with ILM peeling followed by sterile air or silicone oil tamponade and followed up at least 12mo.Based on the features on spectral-domain optical coherence tomography(SD-OCT),the eyes were divided into the MF-only group(Group A,n=15 eyes),MF with central foveal detachment group(Group B,n=20 eyes),and MF with lamellar macular hole group(Group C,n=13 eyes).According to AL,eyes were further divided into three groups:Group D(26.01-28.00 mm,n=12 eyes),Group E(28.01-30.00 mm,n=26 eyes),and Group F(30.01-32.00 mm,n=10 eyes).The best-corrected visual acuity(BCVA),central foveal thickness(CFT),and complications were recorded.RESULTS:The patients included 16 males and 24 females with the mean age of 56±9.82y.The BCVA and CFT improved in all groups after surgery(P<0.01),while there was no significant difference of the CFT in Group A,B,and C postoperatively(P>0.05).The intergroup differences of BCVA and CFT postoperatively were statistically significant in Group D,E,and F.Twenty eyes were injected with sterile air,and 28 eyes were injected with silicone oil for tamponade based on the AL.However,there was no statistically significant difference among Groups D,E,and F in terms of the results of sterile air or silicone oil tamponade.The mean recovery time was 5.9mo for MF patients subjected to silicone oil tamponade and 7.7mo for patients subjected to sterile air tamponade,and the difference was not statistically significant.CONCLUSION:PPV and ILM peeling combined with silicone oil or sterile air tamponade can achieve good results for MF in highly myopic eyes with ALs≤32 mm.
基金Youth Project of Liangxiang Hospital Fangshan District Beijing,No.2022-11.
文摘BACKGROUND Diabetic macular edema(DME),a chronic microvascular complication of diabetes,is a leading cause of visual impairment and blindness.Pars plana vitrectomy(PPV)can restore the normal macular structure and reduce macular edema,whereas internal limiting membrane(ILM)peeling is used to treat tractional macular diseases.Despite the advantages,there is limited research on the combined effects of PPV with ILM peeling.AIM To observe the effects of PPV combined with ILM peeling on postoperative central macular thickness(CMT),best-corrected visual acuity(BCVA),cystoid macular edema(CME)volume,and complications in patients with DME.METHODS Eighty-one patients(92 eyes)diagnosed with DME at the Beijing Shanqu Liangxiang Hospital between January and December 2022 were randomly divided to undergo PPV alone(control group:41 patients,47 eyes)or PPV+ILM peeling(stripping group:40 patients,45 eyes);a single surgeon performed all surgeries.The two groups were compared preoperatively and 1 and 3 months postoperatively.RESULTS Preoperatively,both groups had comparable values of CMT,BCVA,and CME volume(P>0.05).After surgery(both 1 and 3 months),both groups showed significant reductions in CMT,BCVA,and CME volume compared to preoperative levels,with the stripping group showing more significant reductions compared to the control group(P<0.05).Further repeated-measures ANOVA analysis for within-group differences revealed significant effects of group and time,and interaction effects for CMT,BCVA,and CME volume(P<0.05).There were no significant differences in the incidence of complications between the groups(retinal detachment:control=2,stripping=1;endophthalmitis:Control=4,stripping=1;no cases of secondary glaucoma or macular holes;χ^(2)=0.296,P=0.587).CONCLUSION PPV with ILM peeling can significantly improve the visual acuity of patients with DME,reduce CMT,and improve CME with fewer complications.
文摘[Objective] This study aimed to provide basis for rational fertilizer application of wheat in fluvo-aquic soil in the northwest of Shandong Province.[Method] In this paper,the treatments of reduced N,P and K were set in order to explore the effects of fertilizer recommendation based on ASI systematic approach on wheat yield,agronomic efficiency and recovery rate of nutrients.[Result] Nitrogen was the main limiting factor for wheat production in that area,followed by phosphorus,and the third was potassium.Compared with the optimum treatment （OPT）,the reduction of N,P and K reduced the grain yield obviously,which came up to 22.4％,14.4％ and 13.4％ respectively.There were no obvious differences in grain yield among Farmer＇s Fertilization Practice （FP）,60％ OPT-N and OPT treatment.[Conclusion] Agronomic efficiency of N,P and K was 6.3,12.9 and 10 kg/kg respectively.The recovery rates of N,P and K in wheat season were 16.41％,17.27％ and 27.27％ respectively.
文摘A 12 Gbit/s limiting amplifier for fiber-optic transmission system is realized in a 2μm GaAs HBT technology. The whole circuit consists of an input buffer, three similar amplifier cells, an output buffer for driving 50 ft transmission lines and a pair of feedback networks for offset cancellation. At a positive supply voltage of 2 V and a negative supply voltage of - 2V, the power dissipation is about 280 mW. The small-signal gain is higher than 46 dB and the input dynamic range is about 40 dB with a constant single-ended output voltage swing of 400 mV. Satisfactory eye-diagrams are obtained at the bit rate of 12 Gbit/s limited by the test set-up. The chip area is 1.15 mm ×0.7 mm.
基金carried out in the framework of the Research on Regulating Mechanism of Amino Acid Composition of Rumen Microorganism in Ruminant Projectthe financial support from the National Natural Science Foundation of China (30571344)
文摘Three goats fitted with cannula were used to provide rumen liquor to investigate the effects of limiting amino acids on rumen fermentation and microbial community in vitro. The removal method was used in the current experiments. Treatments are total essential amino acid （TEAA）, His-removal, Lys-removal, Met-removal, and branch chain amino acid （BCAA）- removal. Results indicated that, pH-value ranged between 5.9 and 6.8, with the highest mean value for the group with BCAA-removal （6.54） in the culture. Concentration of NH3-N ranged between 10.99 to 30.51 mg 100 mL^-1, with the group of TEAA recording the highest average NH3-N concentration （17.85 mg 100 mL^-1）. Yields of microbial protein and limiting degree on microbial growth varied with treatments （P 〈 0.01）, and the lowest accrued in treatment with BCAA-removal （0.1389, 0.1772, and 0.3161 mg mL^-1 for bacteria, protozoa, and mixed microbes, respectively）, compared to the group with TEAA, microbial production of mixed microbes decreased by 44.52%. As for micro-flora, protozoa to bacteria ratio was the lowest for the group with Lys-removal （89.12%）, while the highest for the group with BCAA-removal （127.60%） （P 〈 0.01）. Furthermore, PCR-SSCP analysis revealed that, microbial profile subjected to substrates within bacteria and protozoa groups. It was therefore concluded that, dietary amino acid influenced both rumen fermentation and microbial characteristics.
文摘Vitrectomy combined with internal limiting membrane(ILM)peeling is popular for the treatment of macular hole(MH).However,the improvements of MH closure rate and postoperative visual acuity are not satisfactory especially in large and refractory MHs.Currently,the ILM flap technique has gradually been applied for the treatment of MH and achieved high MH closure rate.The ILM flap technique has many variations,including the difference of the size,shape,number,and manner in which the flaps put on the MHs.The ILM flap technique also has some auxiliary means including perfluoro-n-octane(PFO),dye,autologous blood and adhesive viscoelastics.There is controversy about the effects between several technique variations of ILM flap,and it needs to be explored in the future.
文摘WT8.BZ]A new quasi 2-dimensional analytical approach to predicting the ring voltage,edge peak fields and optimal spacing of the planar junction with a single floating field limiting ring structure has been proposed,based on the cylindrical symmetric solution and the critical field concept.The effects of the spacing and reverse voltage on the ring junction voltage and edge peak field profiles have been analyzed.The optimal spacing and the maximum breakdown voltage of the structure have also been obtained.The analytical results are in excellent agreement with that obtained from the 2-D device simulator,MEDICI and the reported result,which proves the presented model valid.
文摘A limiting amplifier (LA) IC implemented in TSMC standard 0.25μm CMOS technology is described.Active inductor loads and direct-coupled technology are employed to increase the gain,broaden the bandwidth,reduce the power dissipation,and keep a tolerable noise performance.Under a 3.3V supply voltage,the LA core achieves a gain of 50-dB with a power consumption below 40mW.The measured input sensitivity of the amplifier is better than 5m V _ pp .It can operate at bit rates up to 7Gb/s with an rms jitter of 0.03 UI or less.The chip area is only 0.70mm×0.70mm.According to the measurement results,this IC is expected to work at the standard bit rate levels of 2.5,3.125,and 5Gb/s.
文摘A vertical sandwich deep trench with a field limiting ring is proposed to improve the breakdown voltage of power devices and high voltage devices.Simulation result shows that nearly 100% breakdown voltage of the plane junction can be realized.
文摘This paper presents a 155Mbps limiting amplifier for STM-1 systems of SDH optical communication. It is implemented in CSMC 0.5μm CMOS technology. Under a supply voltage of 3.3V, it has a power consumption of 198mW. The core of the circuit is composed of 6 cascaded amplifiers that are in a conventional structure of differential pairs,an output buffer, and a DC offset cancellation feedback loop. The small signal gain can be adjusted from 74 to 44dB by an off-chip resistor. The chip was packaged before being tested. The experimental results indicate that the circuit has an input dynamic range of 54dB and provides a single-ended output swing of 950mV. Its output eye diagram remains satisfactory when the pseudo-random bit sequence （PRBS） input speed reaches 400Mbps.
文摘[Objective] This paper aimed to understand the area change and distribu- tion of medium-low yield farmland, and offered basis to the improvement of mediumlow farmland and its increase of grain production in Tianjin. [Method] Based on the statistical date of Tianjin and its relevant counties and districts, the yield standard was set up to classify high-yield, medium-yield and low-yield farmland in Tianjin. The author analyzed area change of medium-low yield farmland in six agricultural counties and districts （including Jixian County, Wuqing District, Baodi District, Ninghe County, Jinghai County and Dagang district of Binghai New Area） from 1980 to 2010. [Result] The results showed that the average yield of grain rose from 2 445 kg/hm^2 in 1980 to 5 130 kg/hm^2 in 2010, increasing 109.82%. The area of mediumlow yield farmland was reduced from 291 250.13 hm^2 in 1985 to 76 489.87 hm^2 in 2010, coming down 74%. In Tianjin, the area of medium-low yield farmland of 2010 accounted for 19% of the total farmland, of which the ratios of medium-low yield farmland of Jinghai County, Jixian County, Dagang district of Binghai New Area, Wuqing District, Baodi District and Ninghe County were 43.12%, 18.59%, 17.23%, 14.01%, 7.05% and 0, respectively. Low soil nutrient content, drought and water shortage, as well as soil salinization were the main yield limiting factors to mediumlow yield farmland in Tianjin in 2010. [Conclusion] The countermeasures to improve the medium-low yield farmland were proposed, involving enhancing the investment of the government, strengthening the construction of water conservancy infrastructure, further improving the soil fertility, as well as saline and alkaline land, optimizing the farming system and planting drought and salt tolerance crops, etc.
基金This project is funded by the Dongying Science Development Fund Project(DJ2021013).
文摘Due to the low impedance characteristic of the high voltage direct current(HVDC)grid,the fault current rises extremely fast after a DC-side fault occurs,and this phenomenon seriously endangers the safety of the HVDC grid.In order to suppress the rising speed of the fault current and reduce the current interruption requirements of the main breaker(MB),a fault current limiting hybrid DC circuit breaker(FCL-HCB)has been proposed in this paper,and it has the capability of bidirectional fault current limiting and fault current interruption.After the occurrence of the overcurrent in the HVDC grid,the current limiting circuit(CLC)of FCL-HCB is put into operation immediately,and whether the protected line is cut off or resumed to normal operation is decided according to the fault detection result.Compared with the traditional hybrid DC circuit breaker(HCB),the required number of semiconductor switches and the peak value of fault current after fault occurs are greatly reduced by adopting the proposed device.Extensive simulations also verify the effectiveness of the proposed FCL-HCB.
文摘Jiaozhou Bay data collected from May 1991 to February 1994, in 12 seasonal investigations, and provided the authors by the Ecological Station of Jiaozhou Bay, were analyzed to determine the spatiotemporal variations in temperature, light, nutrients (NO - 3 N, NO - 2 N, NH + 4 N, SiO 2- 3 Si, PO 3- 4 P), phytoplankton, and primary production in Jiaozhou Bay. The results indicated that only silicate correlated well in time and space with, and had important effects on, the characteristics, dynamic cycles and trends of, primary production in Jiaozhou Bay. The authors developed a corresponding dynamic model of primary production and silicate and water temperature. Eq.(1) of the model shows that the primary production variation is controlled by the nutrient Si and affected by water temperature; that the main factor controlling the primary production is Si; that water temperature affects the composition of the structure of phytoplankton assemblage; that the different populations of the phytoplankton assemblage occupy different ecological niches for C , the apparent ratio of conversion of silicate in seawater into phytoplankton biomas and D , the coefficient of water temperature’s effect on phytoplankton biomass. The authors researched the silicon source of Jiaozhou Bay, the biogeochemical sediment process of the silicon, the phytoplankton predominant species and the phytoplankton structure. The authors considered silicate a limiting factor of primary production in Jiaozhou Bay, whose decreasing concentration of silicate from terrestrial source is supposedly due to dilution by current and uptake by phytoplankton; quantified the silicate assimilated by phytoplankton, the intrinsic ratio of conversion of silicon into phytoplankton biomass, the proportion of silicate uptaken by phytoplankton and diluted by current; and found that the primary production of the phytoplankton is determined by the quantity of the silicate assimilated by them. The phenomenon of apparently high plant nutrient concentrations but low phytoplankton biomass in some waters is reasonably explained in this paper.
