期刊文献+
共找到26,039篇文章
< 1 2 250 >
每页显示 20 50 100
Gouge stability controlled by temperature elevation and obsidian addition in basaltic faults and implications for moonquakes 被引量:1
1
作者 Shutian Cao Fengshou Zhang +4 位作者 Mengke An Derek Elsworth Manchao He Hai Liu Luanxiao Zhao 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2024年第9期1273-1282,共10页
Basalt is a major component of the earth and moon crust.Mineral composition and temperature influence frictional instability and thus the potential for seismicity on basaltic faults.We performed velocitystepping shear... Basalt is a major component of the earth and moon crust.Mineral composition and temperature influence frictional instability and thus the potential for seismicity on basaltic faults.We performed velocitystepping shear experiments on basalt gouges at a confining pressure of 100 MPa,temperatures in the range of 100-400℃ and with varied obsidian mass fractions of 0-100%under wet/dry conditions to investigate the frictional strength and stability of basaltic faults.We observe a transition from velocity-neutral to velocity-weakening behaviors with increasing obsidian content.The frictional stability response of the mixed obsidian/basalt gouges is characterized by a transition from velocitystrengthening to velocity-weakening at 200℃ and another transition to velocity-strengthening at temperatures>300℃.Conversely,frictional strengths of the obsidian-bearing gouges are insensitive to temperature and wet/dry conditions.These results suggest that obsidian content dominates the potential seismic response of basaltic faults with the effect of temperature controlling the range of seismogenic depths.Thus,shallow moonquakes tend to occur in the lower lunar crust due to the corresponding anticipated higher glass content and a projected temperature range conducive to velocity-weakening behavior.These observations contribute to a better understanding of the nucleation mechanism of shallow seismicity in basaltic faults. 展开更多
关键词 Fault stability Basaltic fault Temperature elevation Obsidian content Shallow moonquakes
下载PDF
Impact of primary percutaneous coronary intervention on ST-segment elevation myocardial infarction patients:A comprehensive analysis 被引量:1
2
作者 Eza Nawzad Saeed Abdulsatar Kamil Faeq 《World Journal of Experimental Medicine》 2024年第1期58-69,共12页
BACKGROUND Myocardial infarction,particularly ST-segment elevation myocardial infarction(STEMI),is a key global mortality cause.Our study investigated predictors of mortality in 96 STEMI patients undergoing primary pe... BACKGROUND Myocardial infarction,particularly ST-segment elevation myocardial infarction(STEMI),is a key global mortality cause.Our study investigated predictors of mortality in 96 STEMI patients undergoing primary percutaneous coronary intervention at Erbil Cardiac Center.Multiple factors were identified influencing in-hospital mortality.Significantly,time from symptom onset to hospital arrival emerged as a decisive factor.Consequently,our study hypothesis is:"Reducing time from symptom onset to hospital arrival significantly improves STEMI prognosis."AIM To determine the key factors influencing mortality rates in STEMI patients.METHODS We studied 96 consecutive STEMI patients undergoing primary percutaneous coronary intervention(PPCI)at the Erbil Cardiac Center.Their clinical histories were compiled,and coronary evaluations were performed via angiography on admission.Data included comorbid conditions,onset of cardiogenic shock,complications during PPCI,and more.Post-discharge,one-month follow-up assessments were completed.Statistical significance was set at P<0.05.RESULTS Our results unearthed several significant findings.The in-hospital and 30-d mortality rates among the 96 STEMI patients were 11.2%and 2.3%respectively.On the investigation of independent predictors of in-hospital mortality,we identified atypical presentation,onset of cardiogenic shock,presence of chronic kidney disease,Thrombolysis In Myocardial Infarction grades 0/1/2,triple vessel disease,ventricular tachycardia/ventricular fibrillation,coronary dissection,and the no-reflow phenomenon.Specifically,the recorded average time from symptom onset to hospital arrival amongst patients who did not survive was significantly longer(6.92±3.86 h)compared to those who survived(3.61±1.67 h),P<0.001.These findings underscore the critical role of timely intervention in improving the survival outcomes of STEMI patients.CONCLUSION Our results affirm that early hospital arrival after symptom onset significantly improves survival rates in STEMI patients,highlighting the critical need for prompt intervention. 展开更多
关键词 Percutaneous coronary intervention Impact analysis Segment elevation Erbil
下载PDF
Distribution of plant species along the elevation gradient in Pangi, a high altitude and remote eco-region in Western Himalaya, India
3
作者 Anupam BHATT Amit CHAWLA 《Journal of Mountain Science》 SCIE CSCD 2024年第11期3739-3753,共15页
The Himalayan high-altitude eco-regions exhibit higher plant species diversity,and several environmental factors play a crucial role in shaping species distribution and diversity.The aim of the present study is to inv... The Himalayan high-altitude eco-regions exhibit higher plant species diversity,and several environmental factors play a crucial role in shaping species distribution and diversity.The aim of the present study is to investigate the floristic composition,distribution of endemic,threatened and native taxa across the elevation zones and the effect of various environmental factors on species richness pattern along the elevation gradient in Pangi,a remote high-altitude region of Himalaya.We conducted extensive field surveys covering 31 localities and established elevational transects for assessing species distribution and the factors affecting thereof.Additionally,information on nativity,endemism,and IUCN red-list categories of threatened species were compiled from published and online resources.Data were analysed using regression model and Non-Metric Multi-Dimensional Scaling(NMDS).In the present study,we recorded a total of 771 plant species across the region.In regression model,the elevation and anthropogenic variables and their interaction showed significant negative effects on the species richness.Species richness was found to decrease with the increasing elevation,showing a humped shaped pattern,with maximum richness observed in the mid-elevations(2,400m to 3,300m above sea level).The pattern of distribution of native and non-native species along the elevation gradient showed opposite trends,and proportion of native species increased towards the higher elevations.Further,NMDS ordination suggests that zone-I(2,100-2,500m asl)and zone-V(4,001-4,500m asl)had highest differences in species composition,while zone-I,zone-II(2,501-3,000m asl),and zone-III(3,001-3,500m asl)showed higher affinity with respect to their species composition.Thus,the present study revealed that remote and hitherto un-explored Pangi eco-region is rich in floristic diversity and provides pertinent information on the species distribution and composition,and various underlying factors influencing the richness patterns,which is necessary for framing suitable conservation strategies,management plans and futuristic population studies. 展开更多
关键词 elevational gradient FLORISTIC HIMALAYA IUCN NATIVE Richness pattern
下载PDF
Beamspace maximum likelihood algorithm based on sum and difference beams for elevation estimation
4
作者 CHEN Sheng ZHAO Yongbo +1 位作者 HU Yili PANG Xiaojiao 《Journal of Systems Engineering and Electronics》 SCIE CSCD 2024年第3期589-598,共10页
Beamspace super-resolution methods for elevation estimation in multipath environment has attracted significant attention, especially the beamspace maximum likelihood(BML)algorithm. However, the difference beam is rare... Beamspace super-resolution methods for elevation estimation in multipath environment has attracted significant attention, especially the beamspace maximum likelihood(BML)algorithm. However, the difference beam is rarely used in superresolution methods, especially in low elevation estimation. The target airspace information in the difference beam is different from the target airspace information in the sum beam. And the use of difference beams does not significantly increase the complexity of the system and algorithms. Thus, this paper applies the difference beam to the beamformer to improve the elevation estimation performance of BML algorithm. And the direction and number of beams can be adjusted according to the actual needs. The theoretical target elevation angle root means square error(RMSE) and the computational complexity of the proposed algorithms are analyzed. Finally, computer simulations and real data processing results demonstrate the effectiveness of the proposed algorithms. 展开更多
关键词 elevation estimation BEAMSPACE multipath environment maximum likelihood
下载PDF
Comparative Study of Acute Coronary Syndrome with Persistent ST-Segment Elevation (STEMI) between Diabetics and Non-Diabetics in Dakar, Senegal
5
作者 Ngoné Diaba Gaye Aliou Alassane Ngaïdé +4 位作者 Joseph Salvador Mingou Massar Wague Momar Dioum Alassane Mbaye Abdoul Kane 《World Journal of Cardiovascular Diseases》 CAS 2024年第10期631-643,共13页
Introduction: This study aimed to compare the frequency of diabetic and non-diabetic patients admitted for ST-elevation myocardial infarction (STEMI), assess their epidemiological, clinical, and paraclinical profiles,... Introduction: This study aimed to compare the frequency of diabetic and non-diabetic patients admitted for ST-elevation myocardial infarction (STEMI), assess their epidemiological, clinical, and paraclinical profiles, and evaluate their therapeutic strategies and outcomes. Methodology: A descriptive, analytical, comparative study with prospective and retrospective data collection was conducted from April 1, 2020, to March 31, 2021. Diabetic and non-diabetic patients with STEMI admitted to a cardiology department were included. STEMI diagnosis was based on clinical and electrocardiographic criteria showing persistent ST-segment elevation in at least two leads. All patients included in the study signed a written, informed consent form. Data analysis was performed using SPSS, with a p-value ≤ 0.05 considered statistically significant. Results: STEMI prevalence was 15.27%, with 37.11% of patients being diabetic and 62.89% non-diabetic. Diabetic patients had a mean age of 59.2 ± 10.9 years, while non-diabetics averaged 58 ± 13.4 years. Diabetics were predominantly female (72.2%), whereas non-diabetics were mainly male (83.6%). Smoking was less frequent among diabetics (25% vs. 47.54%), but hypertension, obesity, and sedentary lifestyle were more common. Diabetics had an average of 3.5 ± 1.1 risk factors compared to 2.6 ± 1.2 in non-diabetics. Admission delay was longer for diabetics (34.8 ± 51.6 hours vs. 23.3 ± 52.3 hours). Chest pain was the main symptom in both groups. Electrocardiograms showed that anterior and inferior infarctions were most frequent. Triple vessel disease and severe complications, such as cardiogenic shock, were more common in diabetics, who also had higher mortality (5.56% vs. 3.28%). Conclusion: Diabetic STEMI patients represent a high-risk group with distinct clinical features, longer admission delays, and a greater accumulation of cardiovascular risk factors, emphasizing the need for targeted interventions. 展开更多
关键词 Acute Coronary Syndrome with Persistent ST-Segment elevation DIABETES Senegal
下载PDF
From furnace up to freezer:Elevational patterns of plant diversity in Mount Palvar,a semi-arid Irano-Turanian mountain range of southwest Asia
6
作者 Atefeh GHORBANALIZADEH Moslem DOOSTMOHAMMADI 《Journal of Mountain Science》 SCIE CSCD 2024年第7期2236-2248,共13页
Much of the world's biodiversity lies in heterogeneous mountain areas with their diverse environments.As an example,Iranian montane ranges are highly diverse,particularly in the Irano-Turanian phytogeographical re... Much of the world's biodiversity lies in heterogeneous mountain areas with their diverse environments.As an example,Iranian montane ranges are highly diverse,particularly in the Irano-Turanian phytogeographical region.Understanding plant diversity patterns with increasing elevation is of high significance,not least for conservation planning.We studied the pattern of species richness,Shannon diversity,endemic richness,endemics ratio,and richness of life forms along a 3900 m elevational transect in Mount Palvar,overlooking the Lut Desert in Southeast Iran.We also analyzed the effect of environmental variables on species turnover along the vertical gradient.A total of 120 vegetation plots(10 m×10 m)were sampled along the elevational transect containing species and environmental data.To discover plant diversity pattern along the elevational gradient,generalized additive model(GAM)was used.Non-metric multidimensional scaling(NMDS)was applied for illustrating the correlation between species composition and environmental variables.We found hump-shaped pattern for species richness,Shannon diversity,endemic richness,and species richness of different life forms,but a monotonic increasing pattern for ratio of endemic species from low to high elevations.Our study confirms the humped pattern of species richness peaking at intermediate elevations along a complete elevational gradient in a semi-arid mountain.The monotonic increase of endemics ratio with elevation in our area as a case study is consistent with global increase of endemism with elevation.According to our results,temperature and precipitation are two important climatic variables that drive elevational plant diversity,particularly in seasonally dry areas.Our study suggests that effective conservation and management are needed for this low latitude mountain area along with calling for long-term monitoring for species redistribution. 展开更多
关键词 elevational gradient Biodiversity ENDEMIC Generalized additive model Hump-shaped pattern Irano-Turanian region
下载PDF
Casein kinase-2 inhibition promotes retinal ganglion cell survival after acute intraocular pressure elevation
7
作者 Meng Wang Shi-Qi Yao +8 位作者 Yao Huang Jia-Jian Liang Yanxuan Xu Shaowan Chen Yuhang Wang Tsz Kin Ng Wai Kit Chu Qi Cui Ling-Ping Cen 《Neural Regeneration Research》 SCIE CAS CSCD 2024年第5期1112-1118,共7页
Intraocular pressure elevation can induce retinal ganglion cell death and is a clinically reversible risk factor for glaucoma,the leading cause of irreversible blindness.We previously demonstrated that casein kinase-2... Intraocular pressure elevation can induce retinal ganglion cell death and is a clinically reversible risk factor for glaucoma,the leading cause of irreversible blindness.We previously demonstrated that casein kinase-2 inhibition can promote retinal ganglion cell survival and axonal regeneration in rats after optic nerve injury.To investigate the underlying mechanism,in the current study we increased the intraocular pressure of adult rats to 75 mmHg for 2 hours and then administered a casein kinase-2 inhibitor(4,5,6,7-tetrabromo-2-azabenzimidazole or 2-dimethylamino-4,5,6,7-tetrabromo-1H-benzimidazole)by intravitreal injection.We found that intravitreal injection of 4,5,6,7-tetrabromo-2-azabenzimidazole or 2-dimethylamino-4,5,6,7-tetrabromo-1H-benzimidazole promoted retinal ganglion cell survival and reduced the number of infiltrating macrophages.Transcriptomic analysis showed that the mitogen activated protein kinase signaling pathway was involved in the response to intraocular pressure elevation but was not modulated by the casein kinase-2 inhibitors.Furthermore,casein kinase-2 inhibition downregulated the expression of genes(Cck,Htrsa,Nef1,Htrlb,Prph,Chat,Slc18a3,Slc5a7,Scn1b,Crybb2,Tsga10ip,and Vstm21)involved in intraocular pressure elevation.Our data indicate that inhibition of casein kinase-2 can enhance retinal ganglion cell survival in rats after acute intraocular pressure elevation via macrophage inactivation. 展开更多
关键词 casein kinase-2 GLAUCOMA intraocular pressure elevation MACROPHAGES retinal ganglion cells
下载PDF
Elevational and temporal patterns of pollination success in distylous and homostylous buckwheats(Fagopyrum)in the Hengduan Mountains
8
作者 Ling-Yun Wu Shuang-Quan Huang Ze-Yu Tong 《Plant Diversity》 SCIE CAS CSCD 2024年第5期661-670,共10页
Reproductive strategies of sexually dimorphic plants vary in response to the environment.Here,we ask whether the sexual systems of Fagopyrum species(i.e.,selfing homostylous and out-crossing distylous)represent distin... Reproductive strategies of sexually dimorphic plants vary in response to the environment.Here,we ask whether the sexual systems of Fagopyrum species(i.e.,selfing homostylous and out-crossing distylous)represent distinct adaptive strategies to increase reproductive success in changing alpine environments.To answer this question,we determined how spatial and temporal factors(e.g.,elevation and peak flowering time)affect reproductive success(i.e.,stigmatic pollen load)in nine wild Fagopyrum species(seven distylous and two homostylous)among 28 populations along an elevation gradient of 1299-3315 m in the Hengduan Mountains,southwestern China.We also observed pollinators and conducted hundreds of hand pollinations to investigate inter/intra-morph compatibility,self-compatibility and pollen limitation in four Fagopyrum species(two distylous and two homostylous).We found that Fagopyrum species at higher elevation generally had bigger flowers and more stigmatic pollen loads;lateflowering individuals had smaller flowers and lower pollen deposition.Stigmatic pollen deposition was more variable in distylous species than in homostylous species.Although seed set was not pollenlimited in all species,we found that fruit set was much lower in distylous species,which rely on frequent pollinator visits,than in homostylous species capable of autonomous self-pollination.Our findings that pollination success increases at high elevations and decreases during the flowering season suggest that distylous and homostylous species have spatially and temporally distinct reproductive strategies related to environment-dependent pollinator activity. 展开更多
关键词 Biodiversity hotspot elevation gradient FAGOPYRUM Stigmatic pollen load Temporal pattern
下载PDF
The storage and utilization of carbohydrates in response to elevation mediated by tree organs in subtropical evergreen broad-leaved forests
9
作者 Bin Xu Xueli Jiang +4 位作者 Yingying Zong G.Geoff Wang Fusheng Chen Zhenyu Zhao Xiangmin Fang 《Forest Ecosystems》 SCIE CSCD 2024年第1期52-61,共10页
Global climate change can affect tree growth and carbon sink function by influencing plant carbohydrate synthesis and utilization,while elevation can be used as an ideal setting under natural conditions to simulate cl... Global climate change can affect tree growth and carbon sink function by influencing plant carbohydrate synthesis and utilization,while elevation can be used as an ideal setting under natural conditions to simulate climate change effects.The effect of elevation on tree growth may depend on organ type.However,the allocation patterns of nonstructural and structural carbohydrates(NSCs and SCs,respectively)in different tree organs and their response to elevation remain unclear.We selected four dominant tree species,Schima superba,Castanopsis eyrei,Castanopsis fargesii and Michelia maudiae,along an elevation gradient from 609 to 1,207 m in subtropical evergreen broad-leaved forests and analyzed leaf,trunk,and fine root NSCs,carbon(C),nitrogen(N)and phosphorus(P)concentrations and the relative abundance of SCs.Leaf NSCs increased initially and then decreased,and trunk NSCs increased with increasing elevation.However,root NSCs decreased with increasing elevation.The relative abundance of SCs in leaves and trunks decreased,while the relative abundance of root SCs increased with increasing elevation.No significant correlations between SCs and NSCs in leaves were detected,while there were negative correlations between SCs and NSCs in trunks,roots,and all organs.Hierarchical partitioning analysis indicated that plant C/N and C/P were the main predictors of changes in SCs and NSCs.Our results suggest that tree organs have divergent responses to elevation and that increasing elevation will inhibit the aboveground part growth and enhance the root growth of trees.A tradeoff between the C distribution used for growth and storage was confirmed along the elevation gradient,which is mainly manifested in the"sink"organs of NSCs.Our results provide insight into tree growth in the context of global climate change scenarios in subtropical forest ecosystems. 展开更多
关键词 Nonstructural carbohydrates Structural carbohydrates elevation Subtropical evergreen broad-leaved forests Tree organs
下载PDF
Technical efficiency of cocoa farms at varying elevation levels in Davao City, Philippines: implications to sustainable upland farming systems
10
作者 Francis Levi A.DURANO Jon Marx SARMIENTO +1 位作者 Larry N.DIGAL Pedro A.ALVIOLA IV 《Journal of Mountain Science》 SCIE CSCD 2024年第1期33-48,共16页
Elevation is one of many components that influence agriculture, and this in turn affects the level of both inputs and outputs of farmers. This article focuses on the productivity and technical efficiency of 100 cocoa ... Elevation is one of many components that influence agriculture, and this in turn affects the level of both inputs and outputs of farmers. This article focuses on the productivity and technical efficiency of 100 cocoa farms using cross-sectional data from areas ranging from 190 to 1021 m above sea level which were classified as low, medium, and high elevation in Davao City, considered as the chocolate capital of the Philippines. Using stochastic frontier analysis, the results showed that the cost of inputs per ha and the number of cocoa trees per ha significantly increase yield. Farms at high elevations were less technically efficient, as this entails lower temperatures and increased rainfall, and cocoa farming in those areas and conditions can be more challenging, especially with changes in farming practices, terrain, and distance to markets. Other significant variables were age of cocoa farms, married farmers, and age of the farmers. Older farms may be more developed, farmers who are married benefit from their spouses being able to readily contribute as farm labor, and lastly, older farmers' inefficiency may likely stem from nonadaptation of newer farming practices. With an average technical efficiency of 0.61, 0.63, and 0.26 in low, medium, and high elevation areas, respectively, farmers therefore have an incentive to improve farm practices and consider topographical variations found in high elevation areas. Recommendations for the improvement of technical efficiency of cocoa farms are better connectivity to markets, enhancing farm practices, and continuation and improvement of government programs on cocoa with an added emphasis on research. For farmers in high elevation areas, mitigating solutions such as sustainable agriculture practices and ecolabelling are key to improving efficiency and minimizing the potential negative impact on upland farming systems. Moreover, such adaptation measures may also contribute to sustainability of cocoa farming in high elevation areas. 展开更多
关键词 Cocoa farms Cobb-Douglas production function elevation Philippines Stochastic frontier analysis Technical efficiency
下载PDF
Changes in posterior corneal elevation after small incision lenticule extraction for different myopic diopters
11
作者 Xiao-Tong Sun Yang Zhang +5 位作者 Xiao-Kun Mei Nan-Nan Zheng Ling-Zhi Niu Xiao-Li Qu Ai-Ping Song Jian Zhuo 《International Journal of Ophthalmology(English edition)》 SCIE CAS 2024年第3期491-498,共8页
●AIM:To study the changes and effect factors of posterior corneal surface after small incision lenticule extraction(SMILE)with different myopic diopters.●METHODS:Ninety eyes of 90 patients who underwent SMILE were i... ●AIM:To study the changes and effect factors of posterior corneal surface after small incision lenticule extraction(SMILE)with different myopic diopters.●METHODS:Ninety eyes of 90 patients who underwent SMILE were included in this retrospective study.Patients were allocated into three groups based on the preoperative spherical equivalent(SE):low myopia(SE≥-3.00 D),moderate myopia(-3.00 D>SE>-6.00 D)and high myopia(SE≤-6.00 D).Posterior corneal surfaces were measured by a Scheimpflug camera preoperatively and different postoperative times(1wk,1,3,6mo,and 1y).Posterior mean elevation(PME)at 25 predetermined points of 3 concentric circles(2-,4-,and 6-mm diameter)above the best fit sphere was analyzed.●RESULTS:All surgeries were completed uneventfully and no ectasia was found through the observation.The difference of myopia group was significant at the 2-mm ring at 1 and 3mo postoperatively(1mo:P=0.017;3mo:P=0.018).The effect of time onΔPME was statistically significant(2-mm ring:P=0.001;4-mm ring:P<0.001;6-mm ring:P<0.001).The effect of different corneal locations onΔPME was significant except 1wk postoperatively(1mo:P=0.000;3mo:P=0.000;6mo:P=0.001;1y:P=0.001).Posterior corneal stability was linearly correlated with SE,central corneal thickness,ablation depth,residual bed thickness,percent ablation depth and percent stromal bed thickness.●CONCLUSION:The posterior corneal surface changes dynamically after SMILE.No protrusion is observed on the posterior corneal surface in patients with different degrees of myopia within one year after surgery.SMILE has good stability,accuracy,safety and predictability. 展开更多
关键词 MYOPIA posterior corneal elevation corneal ectasia small incision lenticule extraction
下载PDF
Productivity and technical efficiency of Robusta coffee farms at varying elevation categories in Sultan Kudarat, Philippines: implications on sustainability
12
作者 Mark James S.SAGUIMPA Larry N.DIGAL 《Journal of Mountain Science》 SCIE CSCD 2024年第11期3615-3629,共15页
Elevation can affect agricultural outputs,affecting farms’productivity and efficiency.This article identified the significant production inputs influencing productivity and factors influencing technical efficiency(TE... Elevation can affect agricultural outputs,affecting farms’productivity and efficiency.This article identified the significant production inputs influencing productivity and factors influencing technical efficiency(TE)and determined the average TE scores of Robusta coffee farms at varying elevations in Sultan Kudarat,Philippines.Cross-sectional data from the Mahintana Foundation,Inc.using random stratified sampling and power analysis from September 9,2021,to January 13,2022,were used to analyze 604 farms from areas ranging from 0.33 to 1284.18 above mean sea level(amsl),classified as low,medium,and high elevation.Open-Data-Kit-based(ODK)mobile data collection systems were utilized to precisely determine the farms’coordinates and elevation.Using stochastic frontier analysis,results showed that increasing the total fertilizer amount and total trees by 1%significantly increased yield by 0.20%and 0.79%,respectively.Meanwhile,increasing the total land area by 1%,including areas unutilized for coffee farming,decreases total yield by 0.11%.Regarding TE,results showed that TE decreases by approximately 0.58%at high elevations.Meanwhile,increasing net income from coffee farming alone by 1%significantly increases TE by 0.00008%.With an average TE of 0.60,0.77,and 0.63 in low,medium,and high elevations,farms may be incentivized to improve farming practices to increase their TE further.TE improvement recommendations include promoting coffee-agroforestry systems and ecolabelling at medium elevations,such as shade-grown coffee,to promote sustainable production in Robusta coffee farms by assigning a premium to consumers demanding environmental conservation. 展开更多
关键词 Cobb-Douglas production function elevation Philippines Robusta coffee farms Stochastic frontier analysis Technical efficiency
下载PDF
Performance validation of High Mountain Asia 8-meter Digital Elevation Model using ICESat-2 geolocated photons
13
作者 Giribabu DANDABATHULA Subham ROY +7 位作者 Omkar Shashikant GHATAGE Vaibhav Balaso KOLASE Shwetambari SATPUTE Koushik GHOSH Sahibnoor KAUR Satyanarayana PONDARI Apurba Kumar BERA Sushil Kumar SRIVASTAV 《Journal of Mountain Science》 SCIE CSCD 2024年第8期2562-2578,共17页
High Mountain Asia(HMA),recognized as a third pole,needs regular and intense studies as it is susceptible to climate change.An accurate and high-resolution Digital Elevation Model(DEM)for this region enables us to ana... High Mountain Asia(HMA),recognized as a third pole,needs regular and intense studies as it is susceptible to climate change.An accurate and high-resolution Digital Elevation Model(DEM)for this region enables us to analyze it in a 3D environment and understand its intricate role as the Water Tower of Asia.The science teams of NASA realized an 8-m DEM using satellite stereo imagery for HMA,termed HMA 8-m DEM.In this research,we assessed the vertical accuracy of HMA 8-m DEM using reference elevations from ICESat-2 geolocated photons at three test sites of varied topography and land covers.Inferences were made from statistical quantifiers and elevation profiles.For the world’s highest mountain,Mount Everest,and its surroundings,Root Mean Squared Error(RMSE)and Mean Absolute Error(MAE)resulted in 1.94 m and 1.66 m,respectively;however,a uniform positive bias observed in the elevation profiles indicates the seasonal snow cover change will dent the accurate estimation of the elevation in this sort of test sites.The second test site containing gentle slopes with forest patches has exhibited the Digital Surface Model(DSM)features with RMSE and MAE of 0.58 m and 0.52 m,respectively.The third test site,situated in the Zanda County of the Qinghai-Tibet,is a relatively flat terrain bed,mostly bare earth with sudden river cuts,and has minimal errors with RMSE and MAE of 0.32 m and 0.29 m,respectively,and with a negligible bias.Additionally,in one more test site,the feasibility of detecting the glacial lakes was tested,which resulted in exhibiting a flat surface over the surface of the lakes,indicating the potential of HMA 8-m DEM for deriving the hydrological parameters.The results accrued in this investigation confirm that the HMA 8-m DEM has the best vertical accuracy and should be of high use for analyzing natural hazards and monitoring glacier surfaces. 展开更多
关键词 High Mountain Asia Digital elevation Model ICESat-2 geolocated photons Accuracy assessment
下载PDF
Elevational patterns of warming effects on plant community and topsoil properties: focus on subalpine meadows ecosystem
14
作者 HAO Aihua LUO Zhengming CHEN Xiaojiang 《Journal of Mountain Science》 SCIE CSCD 2024年第1期146-159,共14页
Climate warming profoundly affects plant biodiversity, community productivity, and soil properties in alpine and subalpine grassland ecosystems. However, these effects are poorly understood across elevational gradient... Climate warming profoundly affects plant biodiversity, community productivity, and soil properties in alpine and subalpine grassland ecosystems. However, these effects are poorly understood across elevational gradients in subalpine meadow ecosystems. To reveal the elevational patterns of warming effects on plant biodiversity, community structure, productivity, and soil properties, we conducted a warming experiment using open-top chambers from August 2019 to August 2022 at high(2764 m a. s. l.), medium(2631 m a. s. l.), and low(2544 m a. s. l.) elevational gradients on a subalpine meadow slope of Mount Wutai, Northern China. Our results showed that three years of warming significantly increased topsoil temperature but significantly decreased topsoil moisture at all elevations(P<0.05), and the percentage of increasing temperature and decreasing moisture both gradually raised with elevation lifting. Warming-induced decreasing proportions of soil organic carbon(SOC, by 19.24%), and total nitrogen(TN, by 24.56%) were the greatest at high elevational gradients. Experimental warming did not affect topsoil C: N, p H, NO_(3)^(-)-N, or NH_(4)^(+)-N at the three elevational gradients. Warming significantly increased species richness(P<0.01) and Shannon-Weiner index(P<0.05) at low elevational gradients but significantly decreased belowground biomass(P<0.05) at a depth of 0–10 cm at three elevational gradients. Warming caused significant increases in the aboveground biomass in the three elevational plots. Warming significantly increased the aboveground biomass of graminoids in medium(by 92.47%) and low(by 98.25%) elevational gradients, that of sedges in high(by 72.44%) and medium(by 57.16%) elevational plots, and that of forbs in high(by 75.88%), medium(by 34.38%), and low(by 74.95%) elevational plots. Species richness had significant linear correlations with SOC, TN, and C: N(P<0.05), but significant nonlinear responses to soil temperature and soil moisture in the warmed treatment(P<0.05). The warmed aboveground biomass had a significant nonlinear response to soil temperature and significant linear responses to soil moisture(P<0.05). This study provided evidence that altitude is a factor in sensitivity to climate warming, and these different parameters(e.g., plant species richness, Shannon-Weiner index, soil temperature, soil moisture, SOC, and TN) can be used to measure this sensitivity. 展开更多
关键词 Warming effect Plant diversity pattern Community structure change elevation gradient Alpine meadow ecosystem Mount Wutai
下载PDF
No generality in biodiversity-productivity relationships along elevation in temperate and subtropical forest landscapes
15
作者 Jiayun Zou Yahuang Luo +12 位作者 Rupert Seidl Dominik Thom Jie Liu Lisa Geres Tobias Richter Linjiang Ye Wei Zheng Liangliang Ma Jie Song Kun Xu Dezhu Li Lianming Gao Sebastian Seibold 《Forest Ecosystems》 SCIE CSCD 2024年第3期255-265,共11页
An improved understanding of biodiversity-productivity relationships(BPRs)along environmental gradients is crucial for effective ecosystem management and biodiversity conservation.The stress-gradient hypothesis sugges... An improved understanding of biodiversity-productivity relationships(BPRs)along environmental gradients is crucial for effective ecosystem management and biodiversity conservation.The stress-gradient hypothesis suggests that BPRs are stronger in stressful environments compared to more favorable conditions.However,there is limited knowledge regarding the variation of BPRs along elevational gradients and their generality across different landscapes.To study how BPRs change with elevation,we harnessed inventory data on 6,431 trees from152 plots surveyed twice in eight to ten year intervals in mountain forests of temperate Europe and subtropical Asia.We quantified the relationship between aboveground productivity and different biodiversity measures,including taxonomic,functional,and phylogenetic diversity.To elucidate the processes underlying BPRs,we studied the variation of different functional traits along elevation across landscapes.We found no general pattern of BPRs across landscapes and elevations.Relationships were neutral for all biodiversity measures in temperate forests,and negative for taxonomic and functional diversity in subtropical forests.BPRs were largely congruent between taxonomic,functional and phylogenetic diversity.We found only weak support for the stress-gradient hypothesis,with BPRs turning from negative to positive(effect not significant)close to the tree line in subtropical forests.In temperate forests,however,elevation patterns were strongly modulated by species identity effects as influenced by specific traits.The effect of traits such as community-weighted mean of maximum plant height and wood density on productivity was congruent across landscapes.Our study highlights the context-dependence of BPRs across elevation gradients and landscapes.Species traits are key modulating factors of BPRs and should be considered more explicitly in studies of the functional role of biodiversity.Furthermore,our findings highlight that potential trade-offs between conserving biodiversity and fostering ecosystem productivity exist,which require more attention in policy and management. 展开更多
关键词 Biodiversity-ecosystem functioning Climate mitigation elevation gradients Forest management Forest productivity Functional traits Nature conservation Phylogenetic diversity
下载PDF
Successful emergency surgical intervention in acute non-STsegment elevation myocardial infarction with rupture:A case report
16
作者 Xing-Po Li Zi-Shan Wang +1 位作者 Hong-Xia Yu Shan-Shan Wang 《World Journal of Clinical Cases》 SCIE 2025年第4期41-47,共7页
BACKGROUND The incidence of acute myocardial infarction(AMI)is rising,with cardiac rupture accounting for approximately 2%of deaths in patients with acute ST-segment elevation myocardial infarction(STEMI).Ventricular ... BACKGROUND The incidence of acute myocardial infarction(AMI)is rising,with cardiac rupture accounting for approximately 2%of deaths in patients with acute ST-segment elevation myocardial infarction(STEMI).Ventricular free wall rupture(FWR)occurs in approximately 2%of AMI patients and is notably rare in patients with non-STEMI.Types of cardiac rupture include left ventricular FWR,ventricular septal rupture,and papillary muscle rupture.The FWR usually leads to acute cardiac tamponade or electromechanical dissociation,where standard resuscitation efforts may not be effective.Ventricular septal rupture and papillary muscle rupture often result in refractory heart failure,with mortality rates over 50%,even with surgical or percutaneous repair options.CASE SUMMARY We present a rare case of an acute non-STEMI patient who suffered sudden FWR causing cardiac tamponade and loss of consciousness immediate before undergoing coronary angiography.Prompt resuscitation and emergency open-heart repair along with coronary artery bypass grafting resulted in successful patient recovery.CONCLUSION This case emphasizes the risks of AMI complications,shares a successful treatment scenario,and discusses measures to prevent such complications. 展开更多
关键词 Acute non-ST segment elevation myocardial infarction Cardiac rupture Acute myocardial infarction Free wall rupture Case report
下载PDF
Intracoronary thrombolysis combined with drug balloon angioplasty in a young ST-segment elevation myocardial infarction patient:A case report
17
作者 Li-Qiong She De-Kui Gao +3 位作者 Le Hong Yin Tian Hui-Zhen Wang Sheng Huang 《World Journal of Cardiology》 2024年第9期531-541,共11页
BACKGROUND The combination of acute ST-segment elevation myocardial infarction(STEMI)and gastric ulcers poses a challenge to primary percutaneous coronary intervention(PPCI),particularly for young patients.The role of... BACKGROUND The combination of acute ST-segment elevation myocardial infarction(STEMI)and gastric ulcers poses a challenge to primary percutaneous coronary intervention(PPCI),particularly for young patients.The role of drug-coated balloons(DCBs)in the treatment of de novo coronary artery lesions in large vessels remains unclear,especially for patients with STEMI.Our strategy is to implement drug balloon angioplasty following the intracoronary administration of low-dose prourokinase and adequate pre-expansion.CASE SUMMARY A 54-year-old male patient presented to the emergency department due to chest pain on June 24,2019.Within the first 3 minutes of the initial assessment in the emergency room,the electrocardiogram(ECG)showed significant changes.There was atrial fibrillation with ST-segment elevation.Subsequently,atrial fibrillation terminated spontaneously and reverted to sinus rhythm.Soon after,the patient experienced syncope.The ECG revealed torsades de pointes ventricular tachycardia.A few seconds later,it returned to sinus rhythm.High-sensitivity tropon in I was normal.The diagnosis was acute STEMI.Emergency coronary angiography revealed subtotal occlusion with thrombus formation in the proximal segment of the left anterior descending artery.Considering the patient's age and history of peptic ulcer disease,after the intracoronary injection of prourokinase,percutaneous transluminal coronary angioplasty and cutting balloon angioplasty were conducted for thorough preconditioning,and paclitaxel drug-eluting balloon angioplasty was performed without any stents,achieving favorable outcomes.CONCLUSION A PPCI without stents may be a viable treatment strategy for select patients with STEMI,and further research is warranted. 展开更多
关键词 STsegment elevation myocardial infarction Recombinant human prourokinase De novo coronary lesion Large vessels Drug-eluting balloon angioplasty Case report
下载PDF
Carbon allocation in Picea jezoensis:Adaptation strategies of a non-treeline species at its upper elevation limit
18
作者 Renkai Dong Na Li +4 位作者 Mai-He Li Yu Cong Haibo Du Decai Gao Hong S.He 《Forest Ecosystems》 SCIE CSCD 2024年第3期347-357,共11页
Understanding the physiological adaptations of non-treeline trees to environmental stress is important to understand future shifts in species composition and distribution of current treeline ecotone.The aim of the pre... Understanding the physiological adaptations of non-treeline trees to environmental stress is important to understand future shifts in species composition and distribution of current treeline ecotone.The aim of the present study was to elucidate the mechanisms of the formation of the upper elevation limit of non-treeline tree species,Picea jezoensis,and the carbon allocation strategies of the species on Changbai Mountain.We employed the^(13)C in situ pulse labeling technique to trace the distribution of photosynthetically assimilated carbon in Picea jezoensis at different elevational positions(tree species at its upper elevation limit(TSAUE,1,700 m a.s.l.)under treeline ecotone;tree species at a lower elevation position(TSALE,1,400 m a.s.l.).We analyzed^(13)C and the non-structural carbohydrate(NSC)concentrations in various tissues following labeling.Our findings revealed a significant shift in carbon allocation in TSAUE compared to TSALE.There was a pronounced increase inδ^(13)C allocation to belowground components(roots,soil,soil respiration)in TSAUE compared to TSALE.Furthermore,the C flow rate within the plant-soil-atmosphere system was faster,and the C residence time in the plant was shorter in TSAUE.The trends indicate enhanced C sink activity in belowground tissues in TSAUE,with newly assimilated C being preferentially directed there,suggesting a more conservative C allocation strategy by P.jezoensis at higher elevations under harsher environments.Such a strategy,prioritizing C storage in roots,likely aids in withstanding winter cold stress at the expense of aboveground growth during the growing season,leading to reduced growth of TSAUE compared to TSALE.The results of the present study shed light on the adaptive mechanisms governing the upper elevation limits of non-treeline trees,and enhances our understanding of how non-treeline species might respond to ongoing climate change. 展开更多
关键词 ^(13)C pulse labeling Carbon distribution Non-structural carbohydrates(NSC) Non-treeline species Sink activity Stressful environments Upper elevation limit
下载PDF
Comprehensive analysis of the impact of primary percutaneous coronary intervention on patients with ST-segment elevation myocardial infarction
19
作者 Ayrton I Bangolo Nikita Wadhwani 《World Journal of Experimental Medicine》 2024年第4期170-173,共4页
This comprehensive analysis by Saeed and Faeq investigates the impact of primary percutaneous coronary intervention(pPCI)on mortality among patients with ST-segment elevation myocardial infarction(STEMI)at the Erbil C... This comprehensive analysis by Saeed and Faeq investigates the impact of primary percutaneous coronary intervention(pPCI)on mortality among patients with ST-segment elevation myocardial infarction(STEMI)at the Erbil Cardiac Center.Analyzing data from 96 consecutive STEMI patients,the study identified significant predictors of in-hospital mortality,emphasizing the critical impact of time of hospital arrival post-symptom onset on overall prognosis.Findings indicate that factors such as atypical presentation,cardiogenic shock,chronic kidney disease,and specific coronary complications are associated with higher mortality rates.The study underscores the necessity of prompt medical intervention for improving survival outcomes in STEMI patients,especially in the high-risk subgroup.This research offers valuable insights into optimizing STEMI management and enhancing patient survival rates through effective and timely pPCI. 展开更多
关键词 ST-segment elevation myocardial infarction Primary percutaneous coronary intervention Mortality predictors Timely hospital arrival Cardiogenic shock
下载PDF
A Comparative Study of Risk Factors and Prognosis in Young and Elderly Patients with Acute ST-Segment Elevation Myocardial Infarction
20
作者 Shaohua Wang Dianyao Ruan +3 位作者 Min Zhang Hongya Zhou Wenyuan Wang Ruiwei Guo 《Journal of Clinical and Nursing Research》 2024年第6期266-275,共10页
Objective:To investigate the differences in risk factors and prognosis between young and elderly patients with acute ST-segment elevation myocardial infarction(STEMI)so as to provide a basis for the prevention of youn... Objective:To investigate the differences in risk factors and prognosis between young and elderly patients with acute ST-segment elevation myocardial infarction(STEMI)so as to provide a basis for the prevention of young patients with acute STEMI.Methods:Patients initially diagnosed with STEMI in the 920"Hospital of Joint Logistic Support Force of PLA from January 1,2018 to December 31,2022 were retrospectively enrolled in this study.A total of 235 STEMI patients aged≤45 years old and 532 STEMI patients aged≥65 years old were screened.The baseline characteristics,laboratory indicators,clinical characteristics,coronary angiography,SYNTAX score and major adverse cardiovascular events(MACE)during 1-year follow-up were analyzed and compared.Results:A total of 767 STEMI patients were enrolled,including 235 in the young group and 532 in the elderly group.Among the STEM patients in the young group,224 cases were male,and smoking and drinking were common.Compared with the elderly group,the young group had shorter hospital stays and more family history of ischemic heart disease(IHD).The level of low-density lipoprotein in the young group was higher than that in the old group,while the level of high-density lipoprotein in the young group was lower than that in the old group.The level of high uric acid and homocysteine in the young group was significantly higher than that in the old group.The main cause of STEMI in the young group was fatigue,and the most common symptom was angina pectoris.Coronary angiography showed that single vessel disease was more common in the young group than in the elderly group,and the lesion in the young group was the left anterior descending artery.The SYNTAX score was significantly lower in the young group than in the elderly group according to the anatomical characteristics of coronary artery disease.In the forest plot,diabetes mellitus and a family history of IHD showed a trend of major adverse cardiovascular events(MACE)in both groups.Conclusion:Males,smokers,alcohol drinkers and family history of ischemic heart disease are more common in young patients.Common risk factors include fatigue,hyperuricemia,hyperlipidemia and so on.In addition,age itself is an independent risk factor.Management of diabetes,hyperuricemia,and homocysteine levels is essential to reduce the incidence of cardiovascular events in young patients.By controlling these factors,the incidence of young patients with acute STEMI can be effectively prevented and the corresponding prevention and treatment basis can be provided. 展开更多
关键词 Acute ST-segment elevation myocardial infarction Young people Elderly people Risk factors
下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部