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Coupled-mode theory for helical fibres
No full textA set of coupled-mode equations for helical fibres are formulated. These equations are then used to analyse the helical single-mode fibres with intrinsic linear birefrinqence. The eigen-modes and the resultant birefringence of the whole waveguides are obtained. The effect of the external perturbation on these waveguide are also considered
A machine-learning method for deriving state-dependent fragility curves of existing steel moment frames with masonry infills
Get PDFFragility assessment of existing low-rise steel moment-resisting frames with masonry infills under mainshock-aftershock earthquake sequences
Get PDFAbstractThis paper presents the fragility assessment of non-seismically designed steel moment frames with masonry infills. The assessment considered the effects of multiple earthquakes on the damage accumulation of steel frames, which is an essential part of modern performance-based earthquake engineering. Effects of aftershocks are particularly important when examining damaged buildings and making post-quake decisions, such as tagging and retrofit strategy. The procedure proposed in the present work includes two phase assessment, which is based on incremental dynamic analyses of two refined numerical models of the case-study steel frame, i.e. with and without masonry infills, and utilises mainshock-aftershock sequences of natural earthquake records. The first phase focuses on the undamaged structure subjected to single and multiple earthquakes; the effects of masonry infills on the seismic vulnerability of the steel frame were also considered. In the second phase, aftershock fragility curves were derived to investigate the seismic vulnerability of infilled steel frames with post-mainshock damage caused by mainshocks. Comparative analyses were conducted among the mainshock-damaged structures considering three post-mainshock damage levels, including no damage. The impact of aftershocks was then discussed for each mainshock-damage level in terms of the breakpoint that marks the onset of exceeding post-mainshock damage level, as well as the probability of exceeding of superior damage level due to more significant aftershocks. The evaluation of the efficiency of commonly used intensity measures of aftershocks was also carried out as part of the second phase of assessment.</jats:p
Numerical Simulations of Exposed Column-Base Plate Connections in Existing Steel Frames
No full textExposed column-base connections in existing steel moment-resisting frames are typically required to transfer simultaneously the axial and shear forces and bending moment to the foundation. This type of connection is usually both semi-rigid and partial-strength, whose behaviour may significantly affect the seismic performance of the structure. However, current code provisions provide limited guidance on the seismic assessment and retrofit of exposed column-base connections in existing frames. Therefore, further studies are needed to investigate the seismic performance of these connections, particularly considering the influence of bi-directional ground motions. To this end, this paper presents the preliminary numerical simulations of a non-seismically designed steel frame to be experimentally investigated within the ERIES-HITBASE project via bi-directional pseudo-dynamic tests. The steel frame consisted of two types of column-base plate connections, i.e., stiffened and unstiffened, representing respectively the base of moment-resisting and gravity frames. The performance of the steel frame was investigated using two finite element models for the column-base connections, supporting the design of the experimental campaig
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
In vitro and in vivo effects of tributyltin on insulin secretion and blood glucose regulation
No full text三丁基錫 (tributyltin，TBT) 是廣泛的環境物染物。文獻指出TBT會造成哺乳類動物的神經毒性、肝毒性、皮膚、免疫毒性及內分泌失調，但對胰島細胞及糖尿病的研究目前尚不清楚，近年來已有報告指出另一有機錫化合物，三苯基錫 (triphenyltin，TPT) 會造成動物模式中高血糖及胰島素分泌減少的症狀，但機轉不明，因此本研究目的在探討TBT對胰島細胞的功能影響、細胞毒性及血糖調控作用並釐清其機制。 研究結果顯示RIN-m5F cells (Rat β-cell line) 在處理較低劑量TBT (0.1 and 0.2 μM) 會刺激胰島素分泌的現象，同時觀察到細胞內鈣離子增加和及PKC活化。N-acetylcystein (NAC，抗氧化劑)、BAPTA/AM (內鈣螯合劑)、Ro32-0432 (PKC抑制劑) 及ICI182780 (雌激素受體拮抗劑) 可以回復TBT造成的胰島素分泌作用。另一方面處理較高劑量的TBT (0.5 and 1 μM) 24 hr後，TBT會造成細胞自體凋亡 (apoptosis)、ROS生成、JNK磷酸化、caspase-3及cleaved PARP活性表現。給予NAC (抗氧化劑)、SP600125 (JNK抑制劑) 及BAPTA/AM (內鈣螯合劑) 可以降低TBT所誘導的細胞自體凋亡及JNK的磷酸化。此外，我們觀察口服餵食TBT (0.025、0.25 mg/kg/day) 實驗小鼠2-4週，發現會有降低血漿胰島素含量、高血糖現象、脂質過氧化物產生及葡萄糖耐受性不良。同時，曝露TBT的實驗小鼠所分離出的胰島細胞 (islets) 會出現胰島素分泌降低現象。NAC (抗氧化劑) 可以改善TBT所造成的反應。 綜合上述結果，較低劑量TBT所造成胰島素分泌作用是透過ROS、Ca2+/PKC訊號傳導或雌激素受體訊號傳導。另一方面，較高劑量的TBT造成β-cells功能喪失、細胞自體凋亡是經由ROS或Ca2+調控JNK的磷酸化、caspase-3活性增加及cleaved PARP表現的訊息傳導路徑。此外，動物實驗證實TBT所誘導的氧化壓力扮演一個很重要的角色。Tributyltin (TBT) is a widespread environmental pollutant. TBT causes neurotoxicity, hepatotoxicity, skin toxicity and immunotoxicity as well as impaired endocrine regulation. However, the pathophysiological effect of TBT on the function of pancreaticβ-cells remains unknown. It has been reported that triphenyltin (TPT), an other organotin compound, could induce hyperglycemia with decreased insulin secretion in vivo, but its mechanism is still unclear. The aim of this study is designed to investigate the effects and mechanisms of TBT on the function of pancreatic β-cells and cell viability and blood glucose regulation. Submicromolar-concentration TBT (0.1 – 1 μM) contains bi-phasic effects on β-cells. 0.1 and 0.2 μM TBT increased insulin secretion, intracellular Ca2+ and stimulated PKC activation in β-cell derived RIN-m5f cells. Antioxidant N-acetylcysteine (NAC), intracellular Ca2+ chelator BAPTA/AM, PKC inhibitor Ro32-0432 and estrogen receptor antagonist ICI182780 significantly reversed TBT-induced increase of insulin secretion. On the other hand, the cell viability and insulin secretion were significantly reduced at 24 hr after 0.5 and 1 μM TBT treatment. We found that higher-dose TBT triggered cell apoptosis, ROS production, phosphorylation of JNK, increase caspase-3 activity and cleaved poly-ADP-ribose polymerase (PARP) expression. Antioxidant NAC, JNK inhibitor SP600125 and intracellular Ca2+ chelator BAPTA/AM prevented TBT-induced cell apoptosis and JNK phosphorylation. We next observed that 2- or 4-week oral exposure of TBT (0.025 and 0.25 mg/kg/day) to mice, significantly caused the decrease in plasma insulin and displayed the elevation of blood glucose and plasma lipid peroxidation and glucose intolerance. Insulin secretion was decrease in islets isolated from TBT-exposed mice. NAC effectively antagonized TBT-induced responses. In conclusion, these results indicate that lower-dose TBT enhanced insulin secretion from pancreatic β-cells, via ROS regulation or Ca2+/PKC pathway or estrogen receptor. On the other hand, the higher-dose TBT triggered pancreatic β-cells dysfunction and apoptosis via ROS or Ca2+/JNK/caspase-3/cleaved PARP signaling pathway. Moreover, oxidative stress may play an important role in TBT-induced responses in vivo.中文摘要 ……………………………………………………………1文摘要 ……………………………………………………………3寫表 ………………………………………………………………5一章 前言.1 三丁基錫 (tributyltin，TBT) 之簡介……………… 6.2 糖尿病與TBT之研究背景 ………………………………8.3 影響胰島素分泌可能的分子機制 ………………………9.4 研究目的 …………………………………………………13二章 材料與方法.1 小鼠胰島細胞分離 ……………………………………14.2 細胞培養 …………………………………………………14.3 細胞存活率試驗 …………………………………………15.4 胰島素分泌試驗 …………………………………………15.5 細胞內ROS含量測定 ……………………………………16.6 細胞內Ca2+測定 ………………………………………16.7 細胞自體凋亡與細胞壞死測試 …………………………17.8 Caspase-3 活性測試 ……………………………………17.9 蛋白質分析-西方點墨法…………………………………17.10 動物處理……………………………………………………20.11 血糖值之測定………………………………………………21.12 口服葡萄糖耐受性測試……………………………………22.13 脂質過氧化測試……………………………………………22.14 實驗數據之統計……………………………………………22三章 結果.1 三丁基錫 (tributyltin，TBT) 對細胞毒性影響及其劑量 的選擇 …………………………………………………23.2 較低劑量TBT對胰島素分泌的影響及其機轉……………25.3 較高劑量TBT造成細胞毒性的作用機轉…………………30.4 TBT對活體的影響 (in vivo test) ……………………36四章 討論 4.1 較低劑量TBT促進胰島素分泌的角色……………………40 4.2 較高劑量TBT造成細胞毒性的角色………………………42 4.3 TBT在活體測試影響及其角色 …………………………44 4.4 結論 ………………………………………………………45考文獻 ……………………………………………………………47表 …………………………………………………………………5
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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