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Search Results: 1 - 10 of 42683 matches for " Xu Qinghai "
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Left Pulmonary Artery Sling Associated with Patent Ductus Arteriosus and Atrial Septal Defect: Evaluation with Multidetector CT  [PDF]
Rukeshman Shakya, Jianhua Liu, Mohit Godar, Qinghai Yuan, Xiaolin Xu
Advances in Computed Tomography (ACT) , 2012, DOI: 10.4236/act.2012.13004
Abstract:

We report a case of left pulmonary artery sling associated with patent ductus arteriosus and atrial septal defect in a 21-month-old child. 256-slice MDCT provides valuable information, such as abnormal origin of the left pulmonary artery, the relationship between pulmonary artery and airway, the diameter of the patent ductus artery and atrial septal defect. The information is helpful in diagnosis, pre-operative evaluation and post-operative follow-up of LPS.

Imaging Features of Eyelid Pilomatraixoma  [PDF]
Bhoj Raj Sharma, Xiaolin Xu, Nannan Xu, Manisha Bajracharya, Madhu Gupta, Qinghai Yuan
Advances in Computed Tomography (ACT) , 2014, DOI: 10.4236/act.2014.32003
Abstract:

Pilomatrixoma is an uncommon benign tumor of matrix cells of hair follicles that rarely involves eyelids. Here we present a case of 4-year-old girl who was brought to hospital with swelling in the left upper eyelid which increased gradually in 1 year. Computed tomography revealed calcified soft tissue mass. The mass was excised successfully and sent for histopathological examination that showed encapsulated tumor composed of eosinophilic ghost cells and basophilic cells suggestive of pilomatrixoma.

Surface pollen and its relationship to vegetation on the southern slope of the eastern Qilian Mountains

LU Xinmiao,CHEN Hui,XU Qinghai,

地理学报 , 2006,
Abstract: The objective of this study is to investigate pollen-vegetation relationship in the Qilian Mountains. The eastern Qilian Mountains are located in the transitional zone of the Tibetan Plateau, the Loess Plateau and the arid region of Northwest China, which is one of the key areas of global environmental change. A total of 13 surface pollen samples from main vegetation have been collected. Pollen percentages were calculated in all samples. In order to reveal the relationship between pollen composition and the vegetation types from which the soil samples have been collected, Detrended Correspondence Analysis (DCA) ordination method was employed on the pollen data. The results show that dominating vegetation types can be recognized by their pollen spectra: Picea crassifolia forest, alpine shrub and alpine meadow as well. Altitude and temperature determine the distribution of the surface pollen and the vegetation. The good agreement between modern vegetation and surface samples across this area provides a measure of the reliability of using pollen data to reconstruct paleoenvironment and paleovegetation patterns in this or other similar regions. However the loss of Betula pollen in forest needs further investigation. Pollen oxidation is the most important factor contributing to the damage of modern pollen in the study area. Pollen concentrations decrease with the increase of pH values of soils, and decrease sharply when the pH exceeds 7.6.
Surface pollen assemblages as indicators of human impact in the warm temperate hilly areas of eastern China
Wei Ding,RuiMing Pang,QingHai Xu,YueCong Li,XianYong Cao
Chinese Science Bulletin , 2011, DOI: 10.1007/s11434-011-4350-1
Abstract: Investigation of 78 surface pollen samples from warm temperate hilly areas of eastern China shows that pollen assemblages in areas of different land use are significantly different. Pollen concentrations in wastelands are higher than in plantations; these, in turn, are higher than in farmlands; implying that pollen concentration decreases with increasing human impact. Arboreal pollen dominated by Pinus and Quercus is common in all samples. Herbaceous pollen percentages are higher while shrub pollen, fern spores and fern allies are lower in farmlands than in wastelands. Crop pollen is only detectable in and near farmlands; its percentages and concentrations decrease in wastelands. Cereal and Cruciferae pollen percentages average 16.7% and 6.7% in farmland respectively, but Cereal reduces to less than 3% and Cruciferae to less than 0.5% in nearby wastelands. Principle coordinates analysis and clustering analysis indicate that pollen assemblages from farmlands are distinguishable from those under other vegetation types. Occurrence of Poaceae, Chenopodiaceae, Artemisia, and Compositae pollen and Selaginella sinensis spores are closely related to human activities, and their types and frequencies indicate intensity of human impact. The spatial distribution of crops, Chenopodiaceae, and Artemisia reflects changes in both natural environments and human activities. Percentages of cereal and Cruciferae pollen, for example, increase with decreasing altitude, but decrease with increasing latitude. Understanding pollen assemblages under artificial and human-disturbed vegetation in hilly areas may aid understanding of human impacts on the plains during the early-middle Holocene.
Discovery of eclogite inclusions and its geological significance in early Jurassic intrusive complex in Xuzhounorthern Anhui, eastern China
Wenliang Xu,Dongyan Wang,Xiaochun Liu,Qinghai Wang,Jingqian Lin
Chinese Science Bulletin , 2002, DOI: 10.1007/BF02907612
Abstract: The early Jurassic intrusive complex is chiefly made of monzodioritic porphyry in northern Anhui and northern Jiangsu, which emplaced in 191 Ma. The intrusive complexes contain a lot of eclogite inclusions which belong to eclogite and garnet-pyroxenite. The inclusions had undergone eclogite facies high-pressure metamorphism and amphibolite facies retrogressive metamorphism. The garnets in eclogite inclusions are mainly almandine varieties and clinopyroxenes are omphacite and augite. The mineral assemblage andP-T estimation results show thatP-T conditions of eclogite facies metamorphism and amphibolite facies retrogressive metamorphism are over 1.2–1.5 GPa, 709–861°C and 0.7–1.03 GPa, 666–738°C, respectively. The discovery of the high-pressure xenoliths not only is of important significance to understand the composition and structure of deep crust in southern edge of North China Platform, but also can be of important influence on realizing the subduction-collision-exhumation evolutional process of the Dabie-Sulu ultrahigh-pressure (UHP) metamorphic belt.
Endovascular treatment of ruptured distal anterior cerebral artery aneurysm
Huang Qinghai,Shen Jie,Xu Yi,Liu Jianmin
Neurology India , 2010,
Abstract: Background: Distal anterior cerebral artery (DACA) aneurysms are less common, accounting for 3.1 to 9.2% of all intracranial aneurysms.The clinical characteristics and surgical techniques are quite different from those of other aneurysms of Willis circle. Objective: We aimed to investigate the clinical and radiographic characteristics of ruptured distal anterior cerebral artery (DACA) aneurysms and the efficacy of endovascular treatment for these lesions. Patients and Methods: From 1998 to 2008, 41 patients with 44 DACA aneurysms were treated by endovascular coiling, including parent vessel occlusion using coils or coils combined with n-butyle-2-cyanoacrylate (NBCA) in two, endosaccular coiling alone in 39, and stent-assisted coiling in three. Results: Technical success was achieved in 40 (97.6%) patients. Among the 41 aneurysms successfully treated with endosaccular coiling or stent-assisted coiling, complete occlusion was obtained in 37, neck remnant in two, and partial occlusion in two. Two patients with poor pretreatment conditions died of cerebral vasospasm. The morbidity was 4.87%. One case each of unruptured recurrence and rebleeding were seen in follow-up DSA of 34 patients and MRA in five cases. Conclusion: Our preliminary results show that endovascular treatment for DACA aneurysms is safe and effective. However, the relative high recurrent rate highlights long-term follow-up for its security.
Influence of Membrane Stress on Seafloor Spreading Driven by Tide-generating Force
Long Chen,Jianguo Chen,Qinghai Xu,Wei Guo
Earth Science Research , 2012, DOI: 10.5539/esr.v1n2p315
Abstract: Although Alfred Lothar Wegener proposed his continental drift hypothesis more than 100 years ago, there has been constant contention regarding the driving source of plate motions. The current geodynamic theory is mainly based on traditional mechanics. The crust is extremely thin in comparison to the earth’s radius, which may be caused by a more complex mechanical system: the mechanics of shells. The mechanics of shells reveals the mechanical effect of the tide-generating force on the earth’s crust. We present a formula that can be used to calculate the membrane stress resulting from the fluctuation of the mantle tide wave in the crust and estimate its magnitude. Although the tidal force is small, the membrane stress is high. Our investigation suggests that the membrane stress is the fundamental reason for rifting and rupture processes at mid-ocean ridges. It is thus the dynamic source for seafloor spreading and plate motion, which offers a reasonable interpretation of various significant problems that are unexplained by mantle convection theory. And there must be the plate tectonics affected by the tidal force is in the terrestrial planets or other celestial bodies.
A Unified Approach to Optimal Opportunistic Spectrum Access under Collision Probability Constraint in Cognitive Radio Systems
Qinghai Xiao,Yunzhou Li,Xiaofeng Zhong,Xibin Xu
EURASIP Journal on Advances in Signal Processing , 2010, DOI: 10.1155/2010/148698
Abstract: We consider a cognitive radio system with one primary channel and one secondary user, and then we introduce a channel-usage pattern model and a fundamental access scheme in this system. Based on this model and fundamental access scheme, we study optimal opportunistic spectrum access problem and formulate it as an optimization problem that the secondary user maximizes spectrum holes utilization under the constraint of collision tolerable level. And then we propose a unified approach to solve this optimization problem. According to the solution of the optimization problem, we analyze and present optimal opportunistic spectrum access algorithms in several cases that the idle period follows uniform distribution, exponential distribution, and Pareto or generalized Pareto distribution. Theoretical analysis and simulation results both show that the optimal opportunistic spectrum access algorithms can maximize spectrum holes utilization under the constraint that the collision probability is bounded below collision tolerable level. The impact of sensing error is also analyzed by simulation.
A Unified Approach to Optimal Opportunistic Spectrum Access under Collision Probability Constraint in Cognitive Radio Systems
Xiao Qinghai,Li Yunzhou,Zhong Xiaofeng,Xu Xibin
EURASIP Journal on Advances in Signal Processing , 2010,
Abstract: We consider a cognitive radio system with one primary channel and one secondary user, and then we introduce a channel-usage pattern model and a fundamental access scheme in this system. Based on this model and fundamental access scheme, we study optimal opportunistic spectrum access problem and formulate it as an optimization problem that the secondary user maximizes spectrum holes utilization under the constraint of collision tolerable level. And then we propose a unified approach to solve this optimization problem. According to the solution of the optimization problem, we analyze and present optimal opportunistic spectrum access algorithms in several cases that the idle period follows uniform distribution, exponential distribution, and Pareto or generalized Pareto distribution. Theoretical analysis and simulation results both show that the optimal opportunistic spectrum access algorithms can maximize spectrum holes utilization under the constraint that the collision probability is bounded below collision tolerable level. The impact of sensing error is also analyzed by simulation.
Pollen flux and vertical dispersion in coniferous and deciduous broadleaved mixed forest in the Changbai Mountains
Xu qinghai Li Yuecong Zhou Liping Li Yiyin Zhang Zhenqing Lin Fengyou,
XU
,QingHai,LI,YueCong,ZHOU,LiPing,LI,YiYin,ZHANG,ZhenQing,LIN,FengYou

科学通报(英文版) , 2007,
Abstract: The pollen flux in coniferous and deciduous broadleaved mixed forest in the Changbai Mountains is presented in one year’s experiments. The results indicate that arboreal pollen percentages are more than 65% and pollen flux is higher than 5000 grain·cm 2·a 1, while less than 2% and lower than 1000 grain·cm 2·a 1 for shrubby pollen, and less than 20% and lower than 3000 grain·cm 2·a 1 for herbaceous pollen for most samples at different heights. The pollen assemblages are similar to those in the samples under 8 m height where Pinus and Quercus are dominant and followed by the few non-local pollen types, and Fraxinus percentages are high with a few non-local pollen types at 16 m to 32 m height as well as non-local pollen clearly increased at 40 m height. Comparisons between pollen assemblages and vegetation composition suggest that similarities are higher for pollen trap samples than for surface moss samples. Supported by the Preliminary Special Foundation for National Key Basic Research (Grant No. 2003CCA01800), the National Natural Science Foundation of China (Grant Nos. 40571166 and 40672107), Hebei Special Foundation for Ph.D (Grant No. 06547006-3) and the Key National Natural Science Foundation of China (Grant No. 40331011)
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