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961.
Implementation of ecological migration (eco-migration) policies may improve the fragile ecological environment of emigration areas; however, it also places enormous pressure on the human-environment systems in immigrant resettlement regions. Via the application of participatory rural appraisal (PRA) methods, ecological footprint (EF), and stochastic impacts by regression on population, affluence, and technology (STIRPAT) models, 21 villages of Huanjiang County in Guangxi Zhuang Autonomous Region, China were used in this research as a case study area for the environmental appraisal of eco-migration policies in immigrant resettlement regions. Results show: (1) In the past 20 years of implementing eco-migration policies, the EF per capita constantly increased, the biocapacity (BC) per capita constantly decreased, and the ecological deficit gradually increased, indicating an extremely negative impact of eco-migration projects on the ecological environment in the immigration areas. (2) Cropland and forest land are the most important components of the per-capita EF. The per-capita EF of cropland experienced overall a first increasing and then decreasing trend, and the per-capita EF of forest land constantly increased and showed the most rapid increase among all types of EF in the last two decades. (3) The proportion of per-capita EF of different types of productive land is in the order of forest land > cropland > carbon uptake land > built-up land > grazing land from high to low, and this is a significant change from the original order of cropland > forest land > carbon uptake land > grazing land > built-up land. (4) Because of unequal possession of ecologically productive resources, the overall per-capita EF, overall per-capita BC, overall per-capita ecological deficit of productive land use by migrants, and their component values of different types of productive land use are all lower than the corresponding values of the natives. The ecological deficit of natives is more severe than that of migrants. (5) Whereas population growth and overexploitation of resources lead directly to the increased pressure on the ecological environment in the immigration areas, increasing nonagricultural income and improving the consumption structure can reduce the dependence of farmers on the land, thus inhibiting the increase of EF. 相似文献
962.
1 Introduction PlanardevelopmentofacurvedsurfaceisbroadlyusedinCAGDandCAD .Accordingtotheirdevelop ment ,surfacesaredividedintodevelopablesurfacesandnon developablesurfaces .Mostofcurvedsurfacesarenon developable ,butbroadlyusedinengineering ,suchasaircraftwings ,laminaofturbine ,fluidsur face .Howeverthedesignandhandlingofcurvedsur faceareverydifficult.Inordertopredigestthecom plexityofdesign ,planardevelopingisintroduced .Non developablesurfacescannotbedevelopedontoaplanewithoutstretch… 相似文献
963.
A double photodiode (PD) constructed by p+/N-well junction and N-well/p-sub junction was designed and fabricated in a UMC 0.18-μm CMOS process. Based on the device structure and mechanism of double PD, a novel small-signal equivalent circuit model considering the carrier transit effect and the parasitic RC time constant was presented. By this model with complete electronic components, the double PD can be incorporated in a commercial circuit simulator. The component values were extracted by fitting the measured S-parameters using simulated annealing algorithm, and a good agreement between the measurement and the simulation results was achieved. 相似文献
964.
Xu-xu Liu Wei-dong Liu Lei Wang Bin Zhu Xiao Shi Zi-xuan Peng He-cheng Zhu Xing-dong Liu Mei-zuo Zhong Dan Xie Mu-sheng Zeng Cai-ping Ren 《Journal of Zhejiang University. Science. B》2018,19(3):171-182
The identification and use of molecular biomarkers have greatly improved the diagnosis and treatment of malignant tumors. However, a much deeper understanding of oncogenic proteins is needed for the benefit to cancer patients. The lipid raft marker proteins, flotillin-1 and flotillin-2, were first found in goldfish retinal ganglion cells during axon regeneration. They have since been found in a variety of cells, mainly on the inner surface of cell membranes, and not only act as a skeleton to provide a platform for protein–protein interactions, but also are involved in signal transduction, nerve regeneration, endocytosis, and lymphocyte activation. Previous studies have shown that flotillins are closely associated with tumor development, invasion, and metastasis. In this article, we review the functions of flotillins in relevant cell processes, their underlying mechanisms of action in a variety of tumors, and their potential applications to tumor molecular diagnosis and targeted therapy. 相似文献
965.
966.
In this study, we present a thermal optimization method using the overall lumped parameter (LP) and partial computational fluid dynamics (CFD) modeling for a 600-kW permanent magnet traction motor developed for high-speed trains. The motor is totally enclosed forced ventilated to achieve high power density, high efficiency, and low maintenance requirements. Considering the electro-magnetic performance, bogie space, and thermal capacity, we propose a ventilation structure with zigzag plates in sector cross-section. We focus particularly on the ventilation channels and propose an overall LP model for thermal optimization, in which the full consideration of the influence of turbulent flow is given by using a partial CFD model. Given the specific critical parameters from the optimization results, we present a complete 3D CFD model of the whole motor to obtain an accurate temperature distribution and the maximum temperature rises in local points. The benefit of zigzag plates is studied extensively using both the LP and the complete CFD models and the results are verified by equivalent thermal experiments under rated operations. Experimental results indicate that the ventilation structure fulfills the normal operational demands of high-speed trains by improving thermal performance by more than 15%. Additionally, we propose an engineering method to estimate iron loss constraint with the complete CFD model to guide the control system design. 相似文献
967.
Study on EEG power and coherence in patients with mild cognitive impairment during working memory task 总被引:3,自引:0,他引:3
蒋正言 《Journal of Zhejiang University. Science. B》2005,6(12):1213-1219
To investigate the features of electroencephalography (EEG) power and coherence at rest and during a working memory task of patients with mild cognitive impairment (MCI). Thirty-five patients (17 males, 18 females; 52~71 years old) and 34 sex- and age-matched controls (17 males, 17 females; 51~63 years old) were recruited in the present study. Mini-Mental State Examination (MMSE) of 35 patients with MCI and 34 normal controls revealed that the scores of MCI patients did not differ significantly from those of normal controls (P>0.05). Then, EEGs at rest and during working memory task with three levels of working memory load were recorded. The EEG power was computed over 10 channels: right and left frontal (F3, F4), central (C3,C4), parietal (P3, P4), temporal (TS, T6) and occipital (O1, O2); inter-hemispheric coherences were computed from five electrode pairs of F3-F4, C3-C4, P3-P4, T5-T6 and O1-O2 for delta (1.0~3.5 Hz), theta (4.0~7.5 Hz), alpha-1 (8.0~10.0 Hz), alpha-2 (10.5~13.0 Hz), beta-1 (13.5~18.0 Hz) and beta-2 (18.5~30.0 Hz) frequency bands. All values of the EEG power of MCI patients were found to be higher than those of normal controls at rest and during working memory tasks. Furthermore, the values of EEG power in the theta, alpha-1, alpha-2 and beta-1 bands of patients with MCI were significantly high (P<0.05) in comparison with those of normal controls. Correlation analysis indicated a significant negative correlation between the EEG powers and MMSE scores. In addition, during working memory tasks, the EEG coherences in all bands were significantly higher in the MCI group in comparison with those in the control group (P<0.05). However, there was no significant difference in EEG coherences between two groups at rest. These findings comprise evidence that MCI patients have higher EEG power at rest, and higher EEG power and coherence during working conditions. It suggests that MCI may be associated with compensatory processes at rest and during working memory tasks. Moreover, failure of normal cortical connections may be exist in MCI patients. 相似文献
968.
This paper presents an overlay network topology called Virtual and Dynamic Hierarchical Architecture (VDHA) for discovering Grid services with high performance. Service discovery based on VDHA has scalable, autonomous, efficient, reliable and quick responsive. We propose two service discovery algorithms. Full Search Query and Discovery Protocol (FSQDP) discovers the nodes that match the request message from all N nodes, which has time complexity O(logN), space complexity O(nvg) (nvg being node numbers of each virtual group), and message-cost O(N), and Domain-Specific Query and Discovery Protocol (DSQDP) searches nodes in only specific domains with time complexity O(nvg), space complexity O(nvg), and message-cost O(nvg). In this paper, we also describe VDHA, its formal definition, and Grid Group Management Protocol. 相似文献
969.
Chol-Kyun Shin 《Asia Pacific Education Review》2016,17(1):133-146
This study examines response patterns of pilot schools in the neo-institutional perspective to make improvements on the pilot school systematic framework. In order to achieve this goal, in-depth interviews were conducted to obtain qualitative data. The results show that pilot schools either (a) actively adopt or (b) ceremonially adopt an education policy through the process of implementation and internalization. Among the sampled schools, only one school showed active adoption, and the other three schools pursued ceremonial adoption. Each school’s response varies according to the internalization level, technical core focus, institutional pressure, and reception of legitimacy. The findings of this study suggest that in order to operate the pilot school ‘as a policy school,’ the school members should truly understand the concept of the policy and actively practice the internalized value through various activities and programs. Furthermore, this study calls for a greater attention to the institutional factors and local contexts. 相似文献
970.