OBJECTIVE:In recent years,the number of clinical research reports on acupuncture and manipulation for the treatment of greater occipital neuralgia has gradually increased,but the quality is uneven.There is currently n...OBJECTIVE:In recent years,the number of clinical research reports on acupuncture and manipulation for the treatment of greater occipital neuralgia has gradually increased,but the quality is uneven.There is currently no literature evaluating the quality of published reports,which is not conducive to the promotion of clinical use of these therapies.Therefore,this article assessed the reporting quality of randomized controlled trials on acupuncture and manipulation for greater occipital neuralgia.METHODS:Cochrane Library,PubMed,Web of Science,Embase,China National Knowledge Infrastructure(CNKI),VIP,WanFang Data,and Chinese BioMedical Literature Database(CBM)from inception to May 20,2024 were searched.The reporting quality of included randomized controlled trials was independently evaluated by two investigators using the CONSORT statement,STRICTA checklist,and Cochrane bias of risk assessment tool.A third investigator resolved any disagreement.RESULTS:A total of 62 articles were included.Based on the CONSORT statement,59.46%(22/37)of all entries had a reporting rate of less than 50%,mainly including“Identification as a randomized trial in the title(1/62,1.61%),”“How sample size was determined(7/62,11.29%),”“Implementation(1/62,1.61%),”“Blinding(1/62,1.61%),”and“Reports of Funding(4/62,6.45%).”According to the STRICTA checklist,29.41%(5/17)of all entries had a reporting rate of less than 50%,mainly including“Details of other interventions(7/58,12.07%),”“Setting and context of treatment(0/58,0%),”and“Description of participating acupuncturists(0/58,0%).”CONCLUSION:The reporting quality of randomized controlled trials on acupuncture and manipulation therapy for greater occipital neuralgia remains low.Future researchers need to make greater efforts to strictly adhere to the CONSORT statement and STRICTA checklist during trial design,implementation,and reporting.This will facilitate the standardization of research in this field and enhance the reliability and reproducibility of the research results.展开更多
High-purity SiO_(2)nanoparticles(SNPs)play a crucial role in various electronic applications,such as semiconductors,solar cells,optical fibers,lenses,and insulating layers,given their purity and particle size,which si...High-purity SiO_(2)nanoparticles(SNPs)play a crucial role in various electronic applications,such as semiconductors,solar cells,optical fibers,lenses,and insulating layers,given their purity and particle size,which significantly impact device efficiency.This study fo-cuses on the synthesis and characterization of pure SNPs through the chemical etching of greater club rush.White powder SNPs were pre-pared using HCl etching,and their thermal behaviors were analyzed via thermogravimetric analysis/differential scanning calorimetry.Structural properties were investigated using X-ray fluorescence,scanning electron microscopy,and transmission electron microscopy.X-ray absorption near-edge structure was employed to assess the oxidation state of the SNPs.The morphology of the SNPs after the first etching was amorphous,with sizes ranging from 50 to 100 nm,which increased to 50-200 nm after the second etching.Despite this size variation,the SNPs maintained a high purity level of 99.8wt%SiO_(2),comparable with industry standards.Notably,the second etching with 0.1-M HCl significantly enhanced the purity level,achieving 99.8wt%SiO_(2)mass.Furthermore,HCl etching facilitated the formation of SiO_(2)in the Si^(4+)oxidation state,akin to industrial SNPs.These findings underscore the critical role of HCl etching in synthesizing high-purity SNPs,with potential applications in advanced electronic devices.展开更多
Investigating the timing and features of climate transitions in East Asia during the Holocene, via the sensitive response of ecosystems on the East Asian Summer Monsoon(EASM) boundary, is crucial for understanding the...Investigating the timing and features of climate transitions in East Asia during the Holocene, via the sensitive response of ecosystems on the East Asian Summer Monsoon(EASM) boundary, is crucial for understanding the underlying mechanisms that drive these transitions. This study presents highresolution palynological sequences for the period 6800–900 cal a B.P. from peat cores retrieved from the Arxan region in the Greater Khingan Range, northeast China. The lithological changes in the cores show that peat deposition began at 6430 cal a B.P. Regional vegetation was dominated by forest steppes, with Artemisia prevailing the vegetation landscape. Variations in Artemisia/Chenopodiaceae(A/C) pollen ratios, Principal Component Analysis(PCA) results, and charcoal concentration derived from the pollen data suggest that regional moisture availability increased from 6800 to 4200 cal a B.P., thereafter experiencing a marked decline. These changes in moisture availability causes fluctuations in the water table of the Arxan marshes, resulting in the expansion and reduction of the marshland, as demonstrated by swamp and aquatic palynomorphs, however did not disrupt subsequent peat deposition. In addition to the forcing of low-latitude summer insolation, the climate transition in northeast China around 4200 cal a B.P. aligns with a notable increase in sea ice in the western Okhotsk Sea during the late Holocene, which probably resulted in a reduction of EASM precipitation over the region. Our study offers new insights into the vegetation response observed in montane marshlands on the EASM boundary to climate transitions during the mid-late Holocene period.展开更多
Recently,the first cross-border matchmaking meeting of 2025 for the application of offshore wind power research outcomes took place in Yangjiang,Guangdong Province.Hosted by the GBA Institute of Industry and Talent(GB...Recently,the first cross-border matchmaking meeting of 2025 for the application of offshore wind power research outcomes took place in Yangjiang,Guangdong Province.Hosted by the GBA Institute of Industry and Talent(GBAIIT),the event spotlighted the cross-axis wind turbine(CAWT),a technology developed by the task force headed by Chong Wen Tong,a fellow with the Academy of Sciences Malaysia and director of the Center for Energy Sciences at the University of Malaya.展开更多
[Objective] This study aims to analyze the natural regeneration characteristics and growth factors of two cut-over lands of Larix gmelini forests in Greater Khingan Mountains. [Method] A database was established based...[Objective] This study aims to analyze the natural regeneration characteristics and growth factors of two cut-over lands of Larix gmelini forests in Greater Khingan Mountains. [Method] A database was established based on the information of natural regeneration cut-over sample plots of Larix gmelini forests in Greater Khingan Mountains. Natural regeneration characteristics of clear-cutting sample plot and shelterwood-cutting sample plot of Larix gmelini in the northern regions of Greater Khingan Mountains were investigated by programming analysis. [Result] The natural regeneration of two principal felling systems was both good, and that of shelterwood-cutting sample plot was better. There were significant linear regression relationships among various growth factors of naturally regenerated plants. [Conclusion] This study provided scientific theoretical guidance for subsequent deforestation and regeneration in Greater Khingan Mountains.展开更多
Based on geographic information system(GIS) spatial analysis technology, the spatial pattern of raster grid transport accessibility for the Guangdong-Hong Kong-Macao Greater Bay area was studied and the states of spat...Based on geographic information system(GIS) spatial analysis technology, the spatial pattern of raster grid transport accessibility for the Guangdong-Hong Kong-Macao Greater Bay area was studied and the states of spatial connectedness were simulated using highway passenger transport, railway passenger transport, port passenger transport and aviation passenger transport data. The result shows that transport accessibility within the Guangdong-Hong Kong-Macao Greater Bay area costs ‘one hour’ and the spatial distribution of accessibility in the area presents clear ‘core-periphery’ spatial characteristics, with Guangzhou, Foshan, Shenzhen constituting the core. The transport accessibility of Guangdong-Hong Kong-Macao is high. Average accessibility of urban nodes as measured by travel time is 0.99 h, and the areas accessible within 1.42 h occupy 79.14% of the total area. Most of the areas with the lowest accessibility are found in the peripheral area, with the worst accessibility being 4.73 h. Compared with the west-side cities, the economically developed east-side cities of the Guangdong-Hong Kong-Macao Greater Bay area have higher connectivity with roads, railways, ports, and aviation transport. Guangzhou, Foshan, Zhuhai, Shenzhen, Hong Kong and Macao are closely linked. The higher the accessibility, the closer the intercity connectedness.展开更多
Background:Migration theory suggests,and some empirical studies show, that in order to compete for the best breeding sites and increase reproductive success,long-distance avian migrants tend to adopt a time minimizati...Background:Migration theory suggests,and some empirical studies show, that in order to compete for the best breeding sites and increase reproductive success,long-distance avian migrants tend to adopt a time minimization strategy during spring migration, resulting in shorter duration spring migration compared to that in autumn.Methods:Using GPS/GSM transmitters,we tracked the full migrations of 11 Greater White-fronted Geese (Anser albifrons) between southeast China and the Russian Arctic,to reveal the migration timing and routes of the East Asian population, and compare the difference in duration between spring and autumn migration of this population.Results:We found that migration in spring (79 ± 12 days) took more than twice as long to cover the same distance as in autumn (35 ±7 days).This difference in migration duration was mainly determined by significantly more time spent in spring (59±16 days) than in autumn (23± 6days) at significantly more stopover sites. Conclusions:We suggest that these geese, thought to be partial capital breeders, spent almost three quarters of total migration time at spring stopover sites to acquire energy stores for ultimate investment in reproduction, although we cannot reject the hypothesis that timing of the spring thaw also contributed to stopover duration.In autumn,they acquired necessary energy stores on the breeding grounds sufficient to reach Northeast China staging areas almost without stop, which reduced stopover times in autumn and resulted in the faster autumn migration than spring.展开更多
The Urban Heat Island (UHI) results in significant and sometimes dramatic increases in air temperature differences between the urban environment and its surrounding areas. The heat island structure may extend from the...The Urban Heat Island (UHI) results in significant and sometimes dramatic increases in air temperature differences between the urban environment and its surrounding areas. The heat island structure may extend from the ground to the top of roofs and canopy levels above ground. The Urban Heat Island effect is a leading factor in a long list of human health problems which are expected to increase with the rapid growth of urban populations and projected future climate change. Urban heat island studies can be conducted through either direct measurements of air temperature using automobile transects and weather station networks or through measuring surface temperature using airborne or satellite remote sensing. In this study, UHI was investigated over the Greater Cairo during both summer and winter seasons over two different dates. Landsat 7 ETM+ data were used and the mono-window algorithm was applied in the study. Results emphasis that both types of heat islands exist in the study area i.e. the surface and the atmospheric heat islands. Temperature differences ranged between 0.5°C to 3.5°C and these are much related to the existing land use/covers. It could be concluded that expansion of urban areas in Greater Cairo has led to increased thermal radiation of land surface on the highly populated areas.展开更多
The Greater Khingan Mountains （Daxinganling） are China＇s important ecological protective screen and also the region most sensitive to climate changes. To gain an in-depth understanding and reveal the climate change...The Greater Khingan Mountains （Daxinganling） are China＇s important ecological protective screen and also the region most sensitive to climate changes. To gain an in-depth understanding and reveal the climate change characteristic in this high-latitude, cold and data-insufficient region is of great importance to maintaining ecological safety and corre- sponding to global climate changes. In this article, the annual average temperature, precipi- tation and sunshine duration series were firstly constructed using tree-ring data and the me- teorological observation data. Then, using the climate tendency rate method, moving-t-testing method, Yamamoto method and wavelet analysis method, we have investigated the climate changes in the region during the past 307 years. Results indicate that, since 1707, the annual average temperature increased significantly, the precipitation increased slightly and the sun- shine duration decreased, with the tendency rates of 0.06~C/10a, 0.79 mm/10a and -5.15 h/10a, respectively （P〈~0.01）. Since the 21 st century, the period with the greatest increase of the annual average temperature （also with the greatest increase of precipitation） corresponds to the period with greatest decrease of sunshine duration. Three sudden changes of the an- nual average temperature and sunshine duration occurred in this period while two sudden changes of precipitation occurred. The strong sudden-change years of precipitation and sunshine duration are basically consistent with the sudden-change years of annual average temperature, suggesting that in the mid-1860s, the climatic sudden change or transition really existed in this region. In the time domain, the climatic series of this region exhibit obvious local variation characteristics. The annual average temperature and sunshine duration exhibit the periodic variations of 25 years while the precipitation exhibits a periodic variation of 20 years. Based on these periodic characteristics, one can infer that in the period from 2013 to 2030, the temperature will be at a high-temperature stage, the precipitation will be at an abundant-precipitation stage and the sunshine duration will be at an less-sunshine stage. In terms of spatial distribution, the leading distribution type of the annual average temperature in this region shows integrity, i.e：, it is easily higher or lower in the whole region; and the second distribution type is more （or less） in the southwest parts and less （or more） in the northeast parts. Precipitation and sunshine duration exhibit complex spatial distribution and include four spatial distribution types. The present study can provide scientific basis for the security in- vestigation of homeland, ecological and water resources as well as economic development programming in China＇s northern borders.展开更多
BACKGROUND: Bile leak remains a main complication in liver transplantation patients with poor biliary tract conditions, mainly caused by an insufficient blood supply or dysplasia of the biliary tract. Although Roux-en...BACKGROUND: Bile leak remains a main complication in liver transplantation patients with poor biliary tract conditions, mainly caused by an insufficient blood supply or dysplasia of the biliary tract. Although Roux-en-Y modus operandi can be adopted, the risk of other complications of the biliary tract such as infection increases. Using pedicled greater omentum flaps to wrap the anastomotic stoma, which increases the biliary tract blood supply, may reduce the incidence of bile leak. METHODS: Fourteen patients undergoing piggy-back liver transplantation and having poor biliary tract conditions were treated with pedicled greater omentum flaps to wrap the anastomotic stoma of the biliary tract. Their clinical data were analyzed retrospectively. RESULTS: Of the 14 patients, only one (7.1%) had a mild bile leak on the 8th day post-operation and fully recovered after symptomatic treatment. The other patients had no biliary complications. CONCLUSIONS: Using pedicled greater omentum flaps to wrap the anastomotic stoma of the biliary tract is an effective way to prevent bile leak in liver transplantation patients, especially those with poor biliary tract conditions. However, experience with this surgical technique still needs to be further explored.展开更多
To report an extragastrointestinal stromal tumor （EGIST） that occurs outside the gastrointestinal tract and shows unique clinicopathologic and immunohistochemical features. In our case, we experienced multiple soft ...To report an extragastrointestinal stromal tumor （EGIST） that occurs outside the gastrointestinal tract and shows unique clinicopathologic and immunohistochemical features. In our case, we experienced multiple soft tissue tumors that originate primarily in the greater omentum, and in immunohistochemical analysis, the tumors showed features that correspond to malignant EGIST. Two large omental masses measured 15 cm×10 cm and 5 cm×4 cm sized and several small ovoid fragments were attached to small intestine, mesentery and peritoneum. On histologic findings, the masses were separated from small bowel serosa and had high mitotic count （115/50 HPFs）. In the results of immunohistochemical stains, the tumor showed CDl17 （c-kit） positive reactivity and high Ki-67 labeling index. On mutation analysis, the c-kit gene mutation was found in the juxtamembrane domain （exon 11）and it was heterozygote. Platelet-derived growth factor receptor （PDGFR） gene mutation was also found in the juxtamemembrane （exon 12） and it was polymorphism. From above findings, we proposed that there may be several mutational pathways to malignant EGIST, so further investigations could be needed to approach this unfavorable disease entity.展开更多
BACKGROUND Most greater tuberosity fractures can be treated without surgery but some have a poor prognosis.The surgical procedures for avulsion fractures of the humeral greater tuberosity include screw fixation,suture...BACKGROUND Most greater tuberosity fractures can be treated without surgery but some have a poor prognosis.The surgical procedures for avulsion fractures of the humeral greater tuberosity include screw fixation,suture anchor fixation,and plate fixation,all of which have treatment-associated complications.To decrease surgical complications,we used a modified suture bridge procedure under direct vision and a minimally invasive small incision to fix fractures of the greater tuberosity of the humerus.AIM To investigate the clinical efficacy and outcomes of minimally invasive modified suture bridge open reduction of greater tuberosity evulsion fractures.METHODS Sixteen patients diagnosed between January 2016 and January 2019 with an avulsion-type greater tuberosity fracture of the proximal humerus and treated by minimally invasive open reduction and modified suture bridges with anchors were studied retrospectively.All were followed up by clinical examination and radiographs at 3 and 6 wk,3,6 and 12 mo after surgery,and thereafter every 6 mo.Outcomes were assessed preoperatively and postoperatively by a visual analog scale(VAS),the University of California Los Angeles(UCLA)shoulder score,the American Shoulder and Elbow Surgeon score(ASES),and range of motion(ROM)for shoulders.RESULTS Seven men and nine women,with an average age of 44.94 years,were evaluated.The time between injury and surgery was 1-2 d,with an average of 1.75 d.The mean operation time was 103.1±7.23 min.All patients achieved bone union within 3 mo after surgery.VAS scores were significantly decreased(P=0.002),and the mean degrees of forward elevation(P=0.047),mean degrees of abduction(P=0.035),ASES score(P=0.092)were increased at 3 wk.The UCLA score was increased at 6 wk(P=0.029)after surgery.The average degrees of external rotation and internal rotation both improved at 3 mo after surgery(P=0.012 and P=0.007,respectively).No procedure-related deaths or incision-related superficial or deep tissue infections occurred.CONCLUSION Modified suture bridge was effective for the treatment of greater tuberosity evulsion fractures,was easier to perform,and had fewer implants than other procedures.展开更多
The Cenozoic Himalayan leucogranite-pegmatite belt has been a hotspot for rare metal exploration in recent years.To determine the genesis of the pegmatite in the Himalayan region and its relationship with the Greater ...The Cenozoic Himalayan leucogranite-pegmatite belt has been a hotspot for rare metal exploration in recent years.To determine the genesis of the pegmatite in the Himalayan region and its relationship with the Greater Himalayan Crystalline Complex(GHC),the Gyirong pegmatite in southern Tibet was chosen for geochronological and geochemical studies.The dating analyses indicate that the U-Th-Pb ages of zircon,monazite,and xenotime exhibit large variations(38.6‒16.1 Ma),with the weighted average value of the four youngest points is 16.5±0.3 Ma,which indicates that the final stage of crystallization of the melt occurred in the Miocene.The age of the muscovite Ar-Ar inverse isochron is 15.2±0.4 Ma,which is slightly later than the intrusion age,showing that a cooling process associated with rapid denudation occurred at 16‒15 Ma.TheεHf(t)values of the Cenozoic anatectic zircons cluster between−12 and−9 with an average of−11.4.The Gyirong pegmatite shows high contents of Si,Al,and K,a high Al saturation index,and low contents of Na,Ca,Fe,Mn,P,Mg,and Ti.Overall,the Gyirong pegmatite is enriched in Rb,Cs,U,K,Th and Pb and depleted in Nb,Ta,Zr,Ti,Eu,Sr,and Ba.The samples show a high 87Sr/86Sr(16 Ma)ratio of ca.0.762 and a lowεNd(16 Ma)value of−16.0.The calculated average initial values of 208Pb/204Pb(16 Ma),207Pb/204Pb(16 Ma)and 206Pb/204Pb(16 Ma)of the whole rock are 39.72,15.79 and 19.56,respectively.The Sr-Nd-Pb-Hf isotopic characteristics of the Gyirong pegmatite are consistent with those of the GHC.This study concludes that the Gyirong pegmatite represents a typical crustal‒derived anatectic pegmatite with low metallogenic potential for rare metals.The Gyirong pegmatite records the long‒term metamorphism and partial melting process of the GHC,and reflects the crustal thickening caused by thrust compression at 39‒29 Ma and the crustal thinning induced by extensional decompression during 28‒15 Ma.展开更多
Extrathoracic solitary fibrous tumors(SFTs) have been described at almost every anatomic location of human body,but reports of SFT in the abdominal cavity are rare.We herein present a rare case of SFT originating from...Extrathoracic solitary fibrous tumors(SFTs) have been described at almost every anatomic location of human body,but reports of SFT in the abdominal cavity are rare.We herein present a rare case of SFT originating from greater omentum.Computed tomography revealed a 15.8 cm × 21.0 cm solid mass located at superior aspect of stomach.Open laparotomy confirmed its mesenchymal origin.Microscopically,its tissue was composed of non-organized and spindle-shaped cells exhibiting atypical nuclei,which were divided up by branching vessel and collagen bundles.Immunohistochemical staining showed that this tumor was negative for CD117,CD99,CD68,cytokeratin,calretinin,desmin,epithelial membrane antigen,F8 and S-100,but positive for CD34,bcl-2,α-smooth muscle actin and vimentin.The patient presented no evidence of recurrence during follow-up.SFT arising from abdominal cavity can be diagnosed by histological findings and immunohistochemical markers,especially for CD34 and bcl-2 positive cases.展开更多
As an important innovation flow,venture capital has been examined in urban network research.However,the segmentation of capital categories and the cross-scale connection of capital remain scarcely analyzed.This study ...As an important innovation flow,venture capital has been examined in urban network research.However,the segmentation of capital categories and the cross-scale connection of capital remain scarcely analyzed.This study focuses on the structure and industry differentiation of venture capital flows in the Guangdong-Hong Kong-Macao Greater Bay Area(GBA)and its cross-scale network characteristics.Based on a venture capital database covering capital amount,investment subject address information,and industry information(2000-2018),this article examines the spatial distribution and network structure of venture capital in the GBA by means of a distance-based test of spatial concentration approach and social network analysis.Key findings show that:(1)Venture capital institutions and startups in the GBA present a high-concentration distribution pattern.In the past 20 years,venture capital activities in the GBA have substantially increased,forming a complex urban network structure with Guangzhou,Shenzhen,and Hong Kong as the core of this network.(2)Different types of venture capital show significantly different urban network structures,with manufacturing,the Internet industry,the financial sector,the cultural media industry,and the medical and health industry as the five industry types with the largest capital flow in the GBA.(3)Cross-scale research on the venture capital network reveals the position of the GBA as a capital hub in China,which forms a dense venture capital connection network with major cities on a national scale.(4)The network structure of venture capital in the GBA is influenced by multi-dimensional proximity,institutional factors,urban economy,and path dependence.Along with these three key mechanisms,the GBA has grown into a national-scale and even global-scale venture capital center.展开更多
China has experienced rapid urbanizations with dramatic land cover changes since 1978. Forest loss is one of land cover changes, and it induces various eco-environmental degradation issues. As one of China’s hotspot ...China has experienced rapid urbanizations with dramatic land cover changes since 1978. Forest loss is one of land cover changes, and it induces various eco-environmental degradation issues. As one of China’s hotspot regions, the Guangdong-Hong KongMacao Greater Bay Area(GBA) has undergone a dramatic urban expansion. To better understand forest dynamics and protect forest ecosystem, revealing the processes, patterns and underlying drivers of forest loss is essential. This study focused on the spatiotemporal evolution and potential driving factors of forest loss in the GBA at regional and city level. The Landsat time-series images from 1987 to2017 were used to derive forest, and landscape metrics and geographic information system(GIS) were applied to implement further spatial analysis. The results showed that: 1) 14.86% of the total urban growth area of the GBA was obtained from the forest loss in1987–2017;meanwhile, the forest loss area of the GBA reached 4040.6 km2, of which 25.60%(1034.42 km2) was converted to urban land;2) the percentages of forest loss to urban land in Dongguan(19.14%), Guangzhou(18.35%) and Shenzhen(15.81%) were higher than those in other cities;3) the forest became increasingly fragmented from 1987–2007, and then the fragmentation decreased from2007 to 2017);4) the landscape responses to forest changes varied with the scale;and 5) some forest loss to urban regions moved from low-elevation and gentle-slope terrains to higher-elevation and steep-slope terrains over time, especially in Shenzhen and Hong Kong.Urbanization and industrialization greatly drove forest loss and fragmentation, and, notably, hillside urban land expansion may have contributed to hillside forest loss. The findings will help policy makers in maintaining the stability of forest ecosystems, and provide some new insights into forest management and conservation.展开更多
Objective To investigate the role of revascularization procedures with autologous greater saphenous vein in surgical management of iliac-femoral artery pseudoaneurysm in parenteral drug abusers. Methods Twenty-one pat...Objective To investigate the role of revascularization procedures with autologous greater saphenous vein in surgical management of iliac-femoral artery pseudoaneurysm in parenteral drug abusers. Methods Twenty-one patients with iliac-femoral artery pseudoaneurysm caused by parenteral drug abuse from 2004 to 2007 were enrolled. Among them,15 patients were male and 6 were female; their average age was 31.3 years. The size of pseudoaneurysms ranged from 3.0 cm to 7.5 cm. Common femoral artery and distal external iliac artery were often involved. We performed arterial reconstruction on these patients with autologous greater saphenous vein as a graft after excising iliac-femoral artery pseudoaneurysm through a single curved inguinal incision. All patients were followed up,and the complications were recorded. Results The surgical procedures were finished without intraoperative mortality or perioperative complications. All patients were free of claudication symptoms after the surgery except one case with preoperative popliteal artery stenosis. One case of infection and wound tissue fistula was found later. One case had inguinal incisional hematoma and another complained of numbness in thigh skin. Conclusions The use of autologous greater saphenous venous grafts for arterial reconstruction after pseudoaneurysm excision in drug abusers is safe and effective. This technique offers more advantages than arterial ligation alone without revascularization. An optimal greater saphenous venous graft is a prerequisite for revascularization.展开更多
The Greater Cairo Region (GCR), Egypt has experienced rapid urban expansion and broad development over the past several decades. Due to such development, this region faces many environmental consequences. In order to ...The Greater Cairo Region (GCR), Egypt has experienced rapid urban expansion and broad development over the past several decades. Due to such development, this region faces many environmental consequences. In order to mitigate such consequences, it is essential to examine the historical change to measure the urban sprawl of GCR, and its effect on land surface temperature (LST). The objective of this study is to fulfill this goal. It does so by generating land use/land cover (LULC) maps derived from Landsat 5 TM for 1990 and 2003 and Landsat 8 OLI for 2016, using several classification techniques. A spectral radiance model and a web-based atmospheric correction model were used to successfully evaluate LST from thermal bands of Landsat data. Overall accuracy of Landsat derived land use data were 90.3%, 96.5% and 94.9% for years 1990, 2003 and 2016, respectively. The LULC change analysis revealed vegetation loss to urban land by an amount of 7.73% and from barren lands to urban uses by 8.70% within a 26-year timespan (1990-2016). This rapid urban growth significantly decreases vegetation areas, consequently increasing the LST and modifying the urban microclimate. Results from this study can help policy-makers characterize the evolution of urban construction for future developments.展开更多
Accurate assessment of postfire vegetation recovery is important for forest management and the conservation of species diversity.Topography is an important factor aff ecting vegetation recovery but whether species com...Accurate assessment of postfire vegetation recovery is important for forest management and the conservation of species diversity.Topography is an important factor aff ecting vegetation recovery but whether species composition varies with diff erent recovery stages and between valleys and slopes is unclear.Using fi eld data and a space-for-time substitution method,we quantifi ed species richness and diversity to obtain the successional trajectories of valleys and slopes.We surveyed the species of 10 burned areas from 1986 to 2010 in the Greater Khingan Mountains in northeastern China,and found that with increasing postfi re recovery time,species richness in both valleys and slopes gradually decreased.However,species richness in valleys was relatively higher.Shrubs recovered rapidly in the valleys,and species diversity maximized approximately 11 years after fi re.However,it maximized 17–18 years after fi re on the slopes.Numerous shade-tolerant species were present in the valleys 11 years after fi re but not until after 18 years on slopes.Larch appeared earlier than 11 years after fi re and its recovery was slow in the valleys but appeared quickly on slopes and established dominance early.Our study provides some new insights into vegetation succession after fi re at local scales.After fi re,the vegetation recovery processes diff er with topography and it aff ects the initial rate of recovery and species composition at diff erent successional stages.展开更多
The potential of citizen science projects in research has been increasingly acknowledged,but the substantial engagement of these projects is restricted by the quality of citizen science data.Based on the largest emerg...The potential of citizen science projects in research has been increasingly acknowledged,but the substantial engagement of these projects is restricted by the quality of citizen science data.Based on the largest emerging citizen science project in the country-Birdreport Online Database(BOD),we examined the biases of birdwatching data from the Greater Bay Area of China.The results show that the sampling effort is disparate among land cover types due to contributors’ preference towards urban and suburban areas,indicating the environment suitable for species existence could be underrepresented in the BOD data.We tested the contributors’ skill of species identification via a questionnaire targeting the citizen birders in the Greater Bay Area.The questionnaire show that most citizen birdwatchers could correctly identify the common species widely distributed in Southern China and the less common species with conspicuous morphological characteristics,while failed to identify the species from Alaudidae;Caprimulgidae,Emberizidae,Phylloscopidae,Scolopacidae and Scotocercidae.With a study example,we demonstrate that spatially clustered bird watching visits can cause underestimation of species richness in insufficiently sampled areas;and the result of species richness mapping is sensitive to the contributors’ skill of identifying bird species.Our results address how avian research can be influenced by the reliability of citizen science data in a region of generally high accessibility,and highlight the necessity of pre-analysis scrutiny on data reliability regarding to research aims at all spatial and temporal scales.To improve the data quality,we suggest to equip the data collection frame of BOD with a flexible filter for bird abundance,and questionnaires that collect information related to contributors’ bird identification skill.Statistic modelling approaches are encouraged to apply for correcting the bias of sampling effort.展开更多
文摘OBJECTIVE:In recent years,the number of clinical research reports on acupuncture and manipulation for the treatment of greater occipital neuralgia has gradually increased,but the quality is uneven.There is currently no literature evaluating the quality of published reports,which is not conducive to the promotion of clinical use of these therapies.Therefore,this article assessed the reporting quality of randomized controlled trials on acupuncture and manipulation for greater occipital neuralgia.METHODS:Cochrane Library,PubMed,Web of Science,Embase,China National Knowledge Infrastructure(CNKI),VIP,WanFang Data,and Chinese BioMedical Literature Database(CBM)from inception to May 20,2024 were searched.The reporting quality of included randomized controlled trials was independently evaluated by two investigators using the CONSORT statement,STRICTA checklist,and Cochrane bias of risk assessment tool.A third investigator resolved any disagreement.RESULTS:A total of 62 articles were included.Based on the CONSORT statement,59.46%(22/37)of all entries had a reporting rate of less than 50%,mainly including“Identification as a randomized trial in the title(1/62,1.61%),”“How sample size was determined(7/62,11.29%),”“Implementation(1/62,1.61%),”“Blinding(1/62,1.61%),”and“Reports of Funding(4/62,6.45%).”According to the STRICTA checklist,29.41%(5/17)of all entries had a reporting rate of less than 50%,mainly including“Details of other interventions(7/58,12.07%),”“Setting and context of treatment(0/58,0%),”and“Description of participating acupuncturists(0/58,0%).”CONCLUSION:The reporting quality of randomized controlled trials on acupuncture and manipulation therapy for greater occipital neuralgia remains low.Future researchers need to make greater efforts to strictly adhere to the CONSORT statement and STRICTA checklist during trial design,implementation,and reporting.This will facilitate the standardization of research in this field and enhance the reliability and reproducibility of the research results.
基金supported by the Suranaree University of Technology(SUT)Center of Excellence(CoE)on Advanced Functional Materials(AFM),School of Physics,Suranaree University of Technology,Nakhon Ratchasima,Thailand,the External Grants and Scholarships for Graduate Students,Suranaree University of Technology,Nakhon Ratchasima,Thailand,and the Research Network on Nanotechnology(RNN),Suranaree University of Technology,Nakhon Ratchasima,Thailand.
文摘High-purity SiO_(2)nanoparticles(SNPs)play a crucial role in various electronic applications,such as semiconductors,solar cells,optical fibers,lenses,and insulating layers,given their purity and particle size,which significantly impact device efficiency.This study fo-cuses on the synthesis and characterization of pure SNPs through the chemical etching of greater club rush.White powder SNPs were pre-pared using HCl etching,and their thermal behaviors were analyzed via thermogravimetric analysis/differential scanning calorimetry.Structural properties were investigated using X-ray fluorescence,scanning electron microscopy,and transmission electron microscopy.X-ray absorption near-edge structure was employed to assess the oxidation state of the SNPs.The morphology of the SNPs after the first etching was amorphous,with sizes ranging from 50 to 100 nm,which increased to 50-200 nm after the second etching.Despite this size variation,the SNPs maintained a high purity level of 99.8wt%SiO_(2),comparable with industry standards.Notably,the second etching with 0.1-M HCl significantly enhanced the purity level,achieving 99.8wt%SiO_(2)mass.Furthermore,HCl etching facilitated the formation of SiO_(2)in the Si^(4+)oxidation state,akin to industrial SNPs.These findings underscore the critical role of HCl etching in synthesizing high-purity SNPs,with potential applications in advanced electronic devices.
基金supported by the National Key Research and Development Program of China (Grant NO.2022YFF0801501)the National Natural Science Foundation of China (Grant NOs.42171157,41907379,and 42101146)+2 种基金Postgraduate Research & Practice Innovation Program of Jiangsu Province (SJCX25_2041)Large Instruments Open Foundation of Nantong University (KFJN2474)Jiangsu Province College Students Innovation and Entrepreneurship Training Program (Grant NOs.S202510304190 and S202510304188)。
文摘Investigating the timing and features of climate transitions in East Asia during the Holocene, via the sensitive response of ecosystems on the East Asian Summer Monsoon(EASM) boundary, is crucial for understanding the underlying mechanisms that drive these transitions. This study presents highresolution palynological sequences for the period 6800–900 cal a B.P. from peat cores retrieved from the Arxan region in the Greater Khingan Range, northeast China. The lithological changes in the cores show that peat deposition began at 6430 cal a B.P. Regional vegetation was dominated by forest steppes, with Artemisia prevailing the vegetation landscape. Variations in Artemisia/Chenopodiaceae(A/C) pollen ratios, Principal Component Analysis(PCA) results, and charcoal concentration derived from the pollen data suggest that regional moisture availability increased from 6800 to 4200 cal a B.P., thereafter experiencing a marked decline. These changes in moisture availability causes fluctuations in the water table of the Arxan marshes, resulting in the expansion and reduction of the marshland, as demonstrated by swamp and aquatic palynomorphs, however did not disrupt subsequent peat deposition. In addition to the forcing of low-latitude summer insolation, the climate transition in northeast China around 4200 cal a B.P. aligns with a notable increase in sea ice in the western Okhotsk Sea during the late Holocene, which probably resulted in a reduction of EASM precipitation over the region. Our study offers new insights into the vegetation response observed in montane marshlands on the EASM boundary to climate transitions during the mid-late Holocene period.
文摘Recently,the first cross-border matchmaking meeting of 2025 for the application of offshore wind power research outcomes took place in Yangjiang,Guangdong Province.Hosted by the GBA Institute of Industry and Talent(GBAIIT),the event spotlighted the cross-axis wind turbine(CAWT),a technology developed by the task force headed by Chong Wen Tong,a fellow with the Academy of Sciences Malaysia and director of the Center for Energy Sciences at the University of Malaya.
基金Supported by Forestry Industry Public Welfare Project of State Forestry Bureau of China(201204205)~~
文摘[Objective] This study aims to analyze the natural regeneration characteristics and growth factors of two cut-over lands of Larix gmelini forests in Greater Khingan Mountains. [Method] A database was established based on the information of natural regeneration cut-over sample plots of Larix gmelini forests in Greater Khingan Mountains. Natural regeneration characteristics of clear-cutting sample plot and shelterwood-cutting sample plot of Larix gmelini in the northern regions of Greater Khingan Mountains were investigated by programming analysis. [Result] The natural regeneration of two principal felling systems was both good, and that of shelterwood-cutting sample plot was better. There were significant linear regression relationships among various growth factors of naturally regenerated plants. [Conclusion] This study provided scientific theoretical guidance for subsequent deforestation and regeneration in Greater Khingan Mountains.
基金Under the auspices of National Natural Science Foundation of China(No.41671160,41701169)
文摘Based on geographic information system(GIS) spatial analysis technology, the spatial pattern of raster grid transport accessibility for the Guangdong-Hong Kong-Macao Greater Bay area was studied and the states of spatial connectedness were simulated using highway passenger transport, railway passenger transport, port passenger transport and aviation passenger transport data. The result shows that transport accessibility within the Guangdong-Hong Kong-Macao Greater Bay area costs ‘one hour’ and the spatial distribution of accessibility in the area presents clear ‘core-periphery’ spatial characteristics, with Guangzhou, Foshan, Shenzhen constituting the core. The transport accessibility of Guangdong-Hong Kong-Macao is high. Average accessibility of urban nodes as measured by travel time is 0.99 h, and the areas accessible within 1.42 h occupy 79.14% of the total area. Most of the areas with the lowest accessibility are found in the peripheral area, with the worst accessibility being 4.73 h. Compared with the west-side cities, the economically developed east-side cities of the Guangdong-Hong Kong-Macao Greater Bay area have higher connectivity with roads, railways, ports, and aviation transport. Guangzhou, Foshan, Zhuhai, Shenzhen, Hong Kong and Macao are closely linked. The higher the accessibility, the closer the intercity connectedness.
基金supported by the National Key Research and Development Programme of China(Grant No.2016YFC0500406)the Chinese Academy of Sciences Key Strategic Programme,Water Ecological Security Assessment,the Major Research Strategy for Middle and Lower Yangtze River(Grant No.ZDRWZS-2017-3-3)the National Natural Science Foundation of China(Grant Nos.31661143027,31670424,31700330)
文摘Background:Migration theory suggests,and some empirical studies show, that in order to compete for the best breeding sites and increase reproductive success,long-distance avian migrants tend to adopt a time minimization strategy during spring migration, resulting in shorter duration spring migration compared to that in autumn.Methods:Using GPS/GSM transmitters,we tracked the full migrations of 11 Greater White-fronted Geese (Anser albifrons) between southeast China and the Russian Arctic,to reveal the migration timing and routes of the East Asian population, and compare the difference in duration between spring and autumn migration of this population.Results:We found that migration in spring (79 ± 12 days) took more than twice as long to cover the same distance as in autumn (35 ±7 days).This difference in migration duration was mainly determined by significantly more time spent in spring (59±16 days) than in autumn (23± 6days) at significantly more stopover sites. Conclusions:We suggest that these geese, thought to be partial capital breeders, spent almost three quarters of total migration time at spring stopover sites to acquire energy stores for ultimate investment in reproduction, although we cannot reject the hypothesis that timing of the spring thaw also contributed to stopover duration.In autumn,they acquired necessary energy stores on the breeding grounds sufficient to reach Northeast China staging areas almost without stop, which reduced stopover times in autumn and resulted in the faster autumn migration than spring.
文摘The Urban Heat Island (UHI) results in significant and sometimes dramatic increases in air temperature differences between the urban environment and its surrounding areas. The heat island structure may extend from the ground to the top of roofs and canopy levels above ground. The Urban Heat Island effect is a leading factor in a long list of human health problems which are expected to increase with the rapid growth of urban populations and projected future climate change. Urban heat island studies can be conducted through either direct measurements of air temperature using automobile transects and weather station networks or through measuring surface temperature using airborne or satellite remote sensing. In this study, UHI was investigated over the Greater Cairo during both summer and winter seasons over two different dates. Landsat 7 ETM+ data were used and the mono-window algorithm was applied in the study. Results emphasis that both types of heat islands exist in the study area i.e. the surface and the atmospheric heat islands. Temperature differences ranged between 0.5°C to 3.5°C and these are much related to the existing land use/covers. It could be concluded that expansion of urban areas in Greater Cairo has led to increased thermal radiation of land surface on the highly populated areas.
基金National Natural Science Foundation of China,No.41165005,No.40865005
文摘The Greater Khingan Mountains （Daxinganling） are China＇s important ecological protective screen and also the region most sensitive to climate changes. To gain an in-depth understanding and reveal the climate change characteristic in this high-latitude, cold and data-insufficient region is of great importance to maintaining ecological safety and corre- sponding to global climate changes. In this article, the annual average temperature, precipi- tation and sunshine duration series were firstly constructed using tree-ring data and the me- teorological observation data. Then, using the climate tendency rate method, moving-t-testing method, Yamamoto method and wavelet analysis method, we have investigated the climate changes in the region during the past 307 years. Results indicate that, since 1707, the annual average temperature increased significantly, the precipitation increased slightly and the sun- shine duration decreased, with the tendency rates of 0.06~C/10a, 0.79 mm/10a and -5.15 h/10a, respectively （P〈~0.01）. Since the 21 st century, the period with the greatest increase of the annual average temperature （also with the greatest increase of precipitation） corresponds to the period with greatest decrease of sunshine duration. Three sudden changes of the an- nual average temperature and sunshine duration occurred in this period while two sudden changes of precipitation occurred. The strong sudden-change years of precipitation and sunshine duration are basically consistent with the sudden-change years of annual average temperature, suggesting that in the mid-1860s, the climatic sudden change or transition really existed in this region. In the time domain, the climatic series of this region exhibit obvious local variation characteristics. The annual average temperature and sunshine duration exhibit the periodic variations of 25 years while the precipitation exhibits a periodic variation of 20 years. Based on these periodic characteristics, one can infer that in the period from 2013 to 2030, the temperature will be at a high-temperature stage, the precipitation will be at an abundant-precipitation stage and the sunshine duration will be at an less-sunshine stage. In terms of spatial distribution, the leading distribution type of the annual average temperature in this region shows integrity, i.e：, it is easily higher or lower in the whole region; and the second distribution type is more （or less） in the southwest parts and less （or more） in the northeast parts. Precipitation and sunshine duration exhibit complex spatial distribution and include four spatial distribution types. The present study can provide scientific basis for the security in- vestigation of homeland, ecological and water resources as well as economic development programming in China＇s northern borders.
文摘BACKGROUND: Bile leak remains a main complication in liver transplantation patients with poor biliary tract conditions, mainly caused by an insufficient blood supply or dysplasia of the biliary tract. Although Roux-en-Y modus operandi can be adopted, the risk of other complications of the biliary tract such as infection increases. Using pedicled greater omentum flaps to wrap the anastomotic stoma, which increases the biliary tract blood supply, may reduce the incidence of bile leak. METHODS: Fourteen patients undergoing piggy-back liver transplantation and having poor biliary tract conditions were treated with pedicled greater omentum flaps to wrap the anastomotic stoma of the biliary tract. Their clinical data were analyzed retrospectively. RESULTS: Of the 14 patients, only one (7.1%) had a mild bile leak on the 8th day post-operation and fully recovered after symptomatic treatment. The other patients had no biliary complications. CONCLUSIONS: Using pedicled greater omentum flaps to wrap the anastomotic stoma of the biliary tract is an effective way to prevent bile leak in liver transplantation patients, especially those with poor biliary tract conditions. However, experience with this surgical technique still needs to be further explored.
文摘To report an extragastrointestinal stromal tumor （EGIST） that occurs outside the gastrointestinal tract and shows unique clinicopathologic and immunohistochemical features. In our case, we experienced multiple soft tissue tumors that originate primarily in the greater omentum, and in immunohistochemical analysis, the tumors showed features that correspond to malignant EGIST. Two large omental masses measured 15 cm×10 cm and 5 cm×4 cm sized and several small ovoid fragments were attached to small intestine, mesentery and peritoneum. On histologic findings, the masses were separated from small bowel serosa and had high mitotic count （115/50 HPFs）. In the results of immunohistochemical stains, the tumor showed CDl17 （c-kit） positive reactivity and high Ki-67 labeling index. On mutation analysis, the c-kit gene mutation was found in the juxtamembrane domain （exon 11）and it was heterozygote. Platelet-derived growth factor receptor （PDGFR） gene mutation was also found in the juxtamemembrane （exon 12） and it was polymorphism. From above findings, we proposed that there may be several mutational pathways to malignant EGIST, so further investigations could be needed to approach this unfavorable disease entity.
基金China Scholarship Council,No.201808080126Incubation Fund of Shandong Provincial Hospital,No.2020FY019+1 种基金Young Scholars Program of Shandong Provincial HospitalNatural Science Foundation of Shandong Province,No.ZR202102180575.
文摘BACKGROUND Most greater tuberosity fractures can be treated without surgery but some have a poor prognosis.The surgical procedures for avulsion fractures of the humeral greater tuberosity include screw fixation,suture anchor fixation,and plate fixation,all of which have treatment-associated complications.To decrease surgical complications,we used a modified suture bridge procedure under direct vision and a minimally invasive small incision to fix fractures of the greater tuberosity of the humerus.AIM To investigate the clinical efficacy and outcomes of minimally invasive modified suture bridge open reduction of greater tuberosity evulsion fractures.METHODS Sixteen patients diagnosed between January 2016 and January 2019 with an avulsion-type greater tuberosity fracture of the proximal humerus and treated by minimally invasive open reduction and modified suture bridges with anchors were studied retrospectively.All were followed up by clinical examination and radiographs at 3 and 6 wk,3,6 and 12 mo after surgery,and thereafter every 6 mo.Outcomes were assessed preoperatively and postoperatively by a visual analog scale(VAS),the University of California Los Angeles(UCLA)shoulder score,the American Shoulder and Elbow Surgeon score(ASES),and range of motion(ROM)for shoulders.RESULTS Seven men and nine women,with an average age of 44.94 years,were evaluated.The time between injury and surgery was 1-2 d,with an average of 1.75 d.The mean operation time was 103.1±7.23 min.All patients achieved bone union within 3 mo after surgery.VAS scores were significantly decreased(P=0.002),and the mean degrees of forward elevation(P=0.047),mean degrees of abduction(P=0.035),ASES score(P=0.092)were increased at 3 wk.The UCLA score was increased at 6 wk(P=0.029)after surgery.The average degrees of external rotation and internal rotation both improved at 3 mo after surgery(P=0.012 and P=0.007,respectively).No procedure-related deaths or incision-related superficial or deep tissue infections occurred.CONCLUSION Modified suture bridge was effective for the treatment of greater tuberosity evulsion fractures,was easier to perform,and had fewer implants than other procedures.
基金sponsored by the National Key R&D Programme of China(2021YFC2901803)National Natural Science Foundation of China(92055314 and 41802095)+2 种基金the China Geological Survey(DD20230049 and DD20220983)is a contribution to the International Geoscience Programme(IGCP-741)Academician Bao-jun Liu Foundation of Southwest Geological Science and Technology Innovation Center.
文摘The Cenozoic Himalayan leucogranite-pegmatite belt has been a hotspot for rare metal exploration in recent years.To determine the genesis of the pegmatite in the Himalayan region and its relationship with the Greater Himalayan Crystalline Complex(GHC),the Gyirong pegmatite in southern Tibet was chosen for geochronological and geochemical studies.The dating analyses indicate that the U-Th-Pb ages of zircon,monazite,and xenotime exhibit large variations(38.6‒16.1 Ma),with the weighted average value of the four youngest points is 16.5±0.3 Ma,which indicates that the final stage of crystallization of the melt occurred in the Miocene.The age of the muscovite Ar-Ar inverse isochron is 15.2±0.4 Ma,which is slightly later than the intrusion age,showing that a cooling process associated with rapid denudation occurred at 16‒15 Ma.TheεHf(t)values of the Cenozoic anatectic zircons cluster between−12 and−9 with an average of−11.4.The Gyirong pegmatite shows high contents of Si,Al,and K,a high Al saturation index,and low contents of Na,Ca,Fe,Mn,P,Mg,and Ti.Overall,the Gyirong pegmatite is enriched in Rb,Cs,U,K,Th and Pb and depleted in Nb,Ta,Zr,Ti,Eu,Sr,and Ba.The samples show a high 87Sr/86Sr(16 Ma)ratio of ca.0.762 and a lowεNd(16 Ma)value of−16.0.The calculated average initial values of 208Pb/204Pb(16 Ma),207Pb/204Pb(16 Ma)and 206Pb/204Pb(16 Ma)of the whole rock are 39.72,15.79 and 19.56,respectively.The Sr-Nd-Pb-Hf isotopic characteristics of the Gyirong pegmatite are consistent with those of the GHC.This study concludes that the Gyirong pegmatite represents a typical crustal‒derived anatectic pegmatite with low metallogenic potential for rare metals.The Gyirong pegmatite records the long‒term metamorphism and partial melting process of the GHC,and reflects the crustal thickening caused by thrust compression at 39‒29 Ma and the crustal thinning induced by extensional decompression during 28‒15 Ma.
文摘Extrathoracic solitary fibrous tumors(SFTs) have been described at almost every anatomic location of human body,but reports of SFT in the abdominal cavity are rare.We herein present a rare case of SFT originating from greater omentum.Computed tomography revealed a 15.8 cm × 21.0 cm solid mass located at superior aspect of stomach.Open laparotomy confirmed its mesenchymal origin.Microscopically,its tissue was composed of non-organized and spindle-shaped cells exhibiting atypical nuclei,which were divided up by branching vessel and collagen bundles.Immunohistochemical staining showed that this tumor was negative for CD117,CD99,CD68,cytokeratin,calretinin,desmin,epithelial membrane antigen,F8 and S-100,but positive for CD34,bcl-2,α-smooth muscle actin and vimentin.The patient presented no evidence of recurrence during follow-up.SFT arising from abdominal cavity can be diagnosed by histological findings and immunohistochemical markers,especially for CD34 and bcl-2 positive cases.
基金National Natural Science Foundation of China(42101182)National Natural Science Foundation of China(42130712)+3 种基金The Technology Plan of Guangzhou(202201010319)GDAS Special Project of Science and Technology Development(2021 GDASYL-20210103004)GDAS Special Project of Science and Technology Development(2020GDASYL-20200104001)GDAS Special Project of Science and Technology Development(2020GDASYL-20200102002)。
文摘As an important innovation flow,venture capital has been examined in urban network research.However,the segmentation of capital categories and the cross-scale connection of capital remain scarcely analyzed.This study focuses on the structure and industry differentiation of venture capital flows in the Guangdong-Hong Kong-Macao Greater Bay Area(GBA)and its cross-scale network characteristics.Based on a venture capital database covering capital amount,investment subject address information,and industry information(2000-2018),this article examines the spatial distribution and network structure of venture capital in the GBA by means of a distance-based test of spatial concentration approach and social network analysis.Key findings show that:(1)Venture capital institutions and startups in the GBA present a high-concentration distribution pattern.In the past 20 years,venture capital activities in the GBA have substantially increased,forming a complex urban network structure with Guangzhou,Shenzhen,and Hong Kong as the core of this network.(2)Different types of venture capital show significantly different urban network structures,with manufacturing,the Internet industry,the financial sector,the cultural media industry,and the medical and health industry as the five industry types with the largest capital flow in the GBA.(3)Cross-scale research on the venture capital network reveals the position of the GBA as a capital hub in China,which forms a dense venture capital connection network with major cities on a national scale.(4)The network structure of venture capital in the GBA is influenced by multi-dimensional proximity,institutional factors,urban economy,and path dependence.Along with these three key mechanisms,the GBA has grown into a national-scale and even global-scale venture capital center.
基金Under the auspices of National Natural Science Foundation of China(No.41890854)Basic Research Program of Shenzhen Science and Technology Innovation Committee(No.JCYJ20180507182022554)+3 种基金National Key R&D Program of China(No.2017YFC0506200)National Natural Science Foundation of China(No.7181101150)National Natural Science Foundation of China(No.41901248)Shenzhen Future Industry Development Funding Program(No.201507211219247860)。
文摘China has experienced rapid urbanizations with dramatic land cover changes since 1978. Forest loss is one of land cover changes, and it induces various eco-environmental degradation issues. As one of China’s hotspot regions, the Guangdong-Hong KongMacao Greater Bay Area(GBA) has undergone a dramatic urban expansion. To better understand forest dynamics and protect forest ecosystem, revealing the processes, patterns and underlying drivers of forest loss is essential. This study focused on the spatiotemporal evolution and potential driving factors of forest loss in the GBA at regional and city level. The Landsat time-series images from 1987 to2017 were used to derive forest, and landscape metrics and geographic information system(GIS) were applied to implement further spatial analysis. The results showed that: 1) 14.86% of the total urban growth area of the GBA was obtained from the forest loss in1987–2017;meanwhile, the forest loss area of the GBA reached 4040.6 km2, of which 25.60%(1034.42 km2) was converted to urban land;2) the percentages of forest loss to urban land in Dongguan(19.14%), Guangzhou(18.35%) and Shenzhen(15.81%) were higher than those in other cities;3) the forest became increasingly fragmented from 1987–2007, and then the fragmentation decreased from2007 to 2017);4) the landscape responses to forest changes varied with the scale;and 5) some forest loss to urban regions moved from low-elevation and gentle-slope terrains to higher-elevation and steep-slope terrains over time, especially in Shenzhen and Hong Kong.Urbanization and industrialization greatly drove forest loss and fragmentation, and, notably, hillside urban land expansion may have contributed to hillside forest loss. The findings will help policy makers in maintaining the stability of forest ecosystems, and provide some new insights into forest management and conservation.
文摘Objective To investigate the role of revascularization procedures with autologous greater saphenous vein in surgical management of iliac-femoral artery pseudoaneurysm in parenteral drug abusers. Methods Twenty-one patients with iliac-femoral artery pseudoaneurysm caused by parenteral drug abuse from 2004 to 2007 were enrolled. Among them,15 patients were male and 6 were female; their average age was 31.3 years. The size of pseudoaneurysms ranged from 3.0 cm to 7.5 cm. Common femoral artery and distal external iliac artery were often involved. We performed arterial reconstruction on these patients with autologous greater saphenous vein as a graft after excising iliac-femoral artery pseudoaneurysm through a single curved inguinal incision. All patients were followed up,and the complications were recorded. Results The surgical procedures were finished without intraoperative mortality or perioperative complications. All patients were free of claudication symptoms after the surgery except one case with preoperative popliteal artery stenosis. One case of infection and wound tissue fistula was found later. One case had inguinal incisional hematoma and another complained of numbness in thigh skin. Conclusions The use of autologous greater saphenous venous grafts for arterial reconstruction after pseudoaneurysm excision in drug abusers is safe and effective. This technique offers more advantages than arterial ligation alone without revascularization. An optimal greater saphenous venous graft is a prerequisite for revascularization.
文摘The Greater Cairo Region (GCR), Egypt has experienced rapid urban expansion and broad development over the past several decades. Due to such development, this region faces many environmental consequences. In order to mitigate such consequences, it is essential to examine the historical change to measure the urban sprawl of GCR, and its effect on land surface temperature (LST). The objective of this study is to fulfill this goal. It does so by generating land use/land cover (LULC) maps derived from Landsat 5 TM for 1990 and 2003 and Landsat 8 OLI for 2016, using several classification techniques. A spectral radiance model and a web-based atmospheric correction model were used to successfully evaluate LST from thermal bands of Landsat data. Overall accuracy of Landsat derived land use data were 90.3%, 96.5% and 94.9% for years 1990, 2003 and 2016, respectively. The LULC change analysis revealed vegetation loss to urban land by an amount of 7.73% and from barren lands to urban uses by 8.70% within a 26-year timespan (1990-2016). This rapid urban growth significantly decreases vegetation areas, consequently increasing the LST and modifying the urban microclimate. Results from this study can help policy-makers characterize the evolution of urban construction for future developments.
基金funded by the National Natural Science Foundation of China(No.41871103).
文摘Accurate assessment of postfire vegetation recovery is important for forest management and the conservation of species diversity.Topography is an important factor aff ecting vegetation recovery but whether species composition varies with diff erent recovery stages and between valleys and slopes is unclear.Using fi eld data and a space-for-time substitution method,we quantifi ed species richness and diversity to obtain the successional trajectories of valleys and slopes.We surveyed the species of 10 burned areas from 1986 to 2010 in the Greater Khingan Mountains in northeastern China,and found that with increasing postfi re recovery time,species richness in both valleys and slopes gradually decreased.However,species richness in valleys was relatively higher.Shrubs recovered rapidly in the valleys,and species diversity maximized approximately 11 years after fi re.However,it maximized 17–18 years after fi re on the slopes.Numerous shade-tolerant species were present in the valleys 11 years after fi re but not until after 18 years on slopes.Larch appeared earlier than 11 years after fi re and its recovery was slow in the valleys but appeared quickly on slopes and established dominance early.Our study provides some new insights into vegetation succession after fi re at local scales.After fi re,the vegetation recovery processes diff er with topography and it aff ects the initial rate of recovery and species composition at diff erent successional stages.
基金the Estuary wetland wildlife survey project of the Greater Bay Area of China(Science and Technology Planning Projects of Guangdong Province,2021B1212110002).
文摘The potential of citizen science projects in research has been increasingly acknowledged,but the substantial engagement of these projects is restricted by the quality of citizen science data.Based on the largest emerging citizen science project in the country-Birdreport Online Database(BOD),we examined the biases of birdwatching data from the Greater Bay Area of China.The results show that the sampling effort is disparate among land cover types due to contributors’ preference towards urban and suburban areas,indicating the environment suitable for species existence could be underrepresented in the BOD data.We tested the contributors’ skill of species identification via a questionnaire targeting the citizen birders in the Greater Bay Area.The questionnaire show that most citizen birdwatchers could correctly identify the common species widely distributed in Southern China and the less common species with conspicuous morphological characteristics,while failed to identify the species from Alaudidae;Caprimulgidae,Emberizidae,Phylloscopidae,Scolopacidae and Scotocercidae.With a study example,we demonstrate that spatially clustered bird watching visits can cause underestimation of species richness in insufficiently sampled areas;and the result of species richness mapping is sensitive to the contributors’ skill of identifying bird species.Our results address how avian research can be influenced by the reliability of citizen science data in a region of generally high accessibility,and highlight the necessity of pre-analysis scrutiny on data reliability regarding to research aims at all spatial and temporal scales.To improve the data quality,we suggest to equip the data collection frame of BOD with a flexible filter for bird abundance,and questionnaires that collect information related to contributors’ bird identification skill.Statistic modelling approaches are encouraged to apply for correcting the bias of sampling effort.
