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RISS 인기검색어
- 검색키워드
- 저자 : Leiming Zhang (검색결과 4 건)
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Systematic and Rigorous Extraction Procedure for InP HBT π-type Small-signal Model Parameters
Jincan Zhang,Leiming Zhang,Min Liu,Liwen Zhang 대한전자공학회 2020 Journal of semiconductor technology and science Vol.20 No.4
In this paper, a systematic and rigorous extraction procedure for InP heterojunction bipolar transistor (HBT) π-type small-signal model parameters is proposed. The AC current crowding effect modeled as a parallel RC circuit is included in the small-signal model of InP HBTs. All of the elements parameters are acquired by means of a systematic and rigorous extraction method based on peeling algorithm, and there is no any simplified approximation. The extraction equations are derived from S-parameters by peeling peripheral elements from small-signal models to get reduced ones, so the extraction technique is more easily understood and clearer. The complete π-type model for an emitter-up InP HBT with 1×15 µm2 emitter area is established and validated, which shows that the small-signal equivalent circuit and elements values extraction method have very high accuracy.
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Na Mi,Guirui Yu,Wuefa Wen,Xiaomin Sun,Shusen Wang,Leiming Zhang,Xia Song 한국기상학회 2009 Asia-Pacific Journal of Atmospheric Sciences Vol.45 No.2
The Qianyanzhou (QYZ) forest site is located in the mid-subtropical region under typical subtropical continentalmonsoon climate. Despite its plentiful water and heat resources, changes in their seasonal distributions result in frequent occurrences of seasonal drought, influencing both the structure and function of forest ecosystems. In order to examine the effects of drought stress on energy and water fluxes and the related physiological processes, we used tower flux measurements from 2003 and 2004 from the QYZ site and the ecosystemmodel EALCO (Ecological Assimilation of Land and Climate Observations). The model explained almost 90%of the variance in the daily LE for both years; whereas 71%and 55% of the variance in H for 2003 and 2004, respectively. Simulations suggested that, during the 2003 summer drought, about 80% of water extraction by roots occurred below 0.45 m, and canopy stomatal conductance decreased in response to soil dryness at a threshold r (relative water content) of 0.5 m. The response of canopy stomatal conductance appeared to be linked to the soil water exposed to themajority of the roots, even if substantialwater was being extracted fromgreater depth. The decrease of canopy stomatal conductance made the ratio of transpiration to ET relatively constant along the years with only a small difference. The different extent of the seasonal drought resulted in different water fluxes for the two years with more distinct influence on evaporation than on transpiration.
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Jian Ren,Xiao Xiao,Li Ruofei,Lv Cheng,Zhang Yu,Leiming Wang,Tao Hong,Hongqi Zhang,Wang Yibo 생화학분자생물학회 2023 Experimental and molecular medicine Vol.55 No.-
Cavernous malformations (CMs) invading the central nervous system occur in ~0.16–0.4% of the general population, often resulting in hemorrhages and focal neurological deficits. Further understanding of disease mechanisms and therapeutic strategies requires a deeper knowledge of CMs in humans. Herein, we performed single-cell RNA sequencing (scRNA-seq) analysis on unselected viable cells from twelve human CM samples and three control samples. A total of 112,670 high-quality cells were clustered into 11 major cell types, which shared a number of common features in CMs harboring different genetic mutations. A new EC subpopulation marked with PLVAP was uniquely identified in lesions. The cellular ligand‒receptor network revealed that the PLVAP-positive EC subcluster was the strongest contributor to the ANGPT and VEGF signaling pathways in all cell types. The PI3K/AKT/mTOR pathway was strongly activated in the PLVAP-positive subcluster even in non-PIK3CA mutation carriers. Moreover, endothelial-to-mesenchymal transition (EndMT) cells were identified for the first time in CMs at the single-cell level, which was accompanied by strong immune activation. The transcription factor SPI1 was predicted to be a novel key driver of EndMT, which was confirmed by in vitro and in vivo studies. A specific fibroblast-like phenotype was more prevalent in lesion smooth muscle cells, hinting at the role of vessel reconstructions and repairs in CMs, and we also confirmed that TWIST1 could induce SMC phenotypic switching in vitro and in vivo. Our results provide novel insights into the pathomechanism decryption and further precise therapy of CMs.
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