1,721,694 research outputs found
CEO Confidence and Unreported R&D
No full text We investigate whether managerial traits influence corporate decisions to provide mandatory financial disclosures. The results indicate that firms with confident chief executive officers (CEOs) are 24% more likely to report their research and development (R&D) expenditures relative to firms with cautious CEOs. Exploiting staggered, state-level regulatory shocks and changes in CEO type, we find substantial evidence that cautious CEO firms fail to report R&D expenditures. After a plausibly exogenous shock to managerial reporting liability, cautious CEO firms exhibit a 35% larger reduction in unreported R&D relative to confident CEO firms. Interestingly, confident CEO firms do not exhibit more innovation than their cautious CEO counterparts after taking into account their differing propensities to report corporate R&D. Overall, our analysis suggests that the precision or reliability of mandatory disclosures systematically varies with managerial characteristics. The Internet appendix is available at https://doi.org/10.1287/mnsc.2017.2809 . This paper was accepted by Amit Seru, finance. </jats:p
Multichannel Poly-Si Thin Film Transistors Prepared by Excimer Laser Annealing with Channel Width Comparable or Smaller than the Grain Size
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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
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
Developing Small Interfering RNA to Intervene Influenza Virus Type A Replication
No full text研究背景：A型流行性感冒病毒估計每年可感染全球人口的20 %，甚至可能因基因重組造成全球大流行。疫苗是用來預防A型流感主要方式，然而疫苗株台灣地區卻僅有53-82 %的保護率，且由於A型流感病毒具有高突變率，使得抗病毒藥物及疫苗很容易失效，因此發展新的預防或治療方式是目前當務之急。微小干擾核醣核酸是細胞用來調控核醣核酸的機制，使得一些核醣核酸不能夠執行其功能。而A型流感病毒之基因片段中有一些長久保存不變的序列已執行重要的功能，這將是微小干擾核醣核酸理想的抑制目標。
研究方法：在兩個A型流感病毒株(A/Panama/1/68, H3N2; A/WSN/33, H1N1)的目標基因(NS1 gene，PA gene，NP gene)之片段中選擇出數個較具高度保留的區域，並在此之間找出適合作為siRNAs標的序列的二十八個核酸序列，重組為可表現short hairpin RNA(shRNA)之質體，並使用轉染溶液jetPEI、Lipofectamine 2000及lentivirus進行MDCK-ATCC與MDCK-p69細胞株轉染。經由紅血球凝集測試、定量PCR或病毒斑分析等方式，觀察其是否具有抑制流感病毒的效果。若找出數個較佳抑制病毒效果的微小干擾核酸之序列，亦進行細胞之共同轉染以觀察有無加成作用。
結果：利用流式細胞儀可發現使用jetPEI與Lipofectamine 2000對MDCK-ATCC之轉染效率各約為20-30 %及34%，轉染效率與繼代數呈反比。文獻中發現具抑制效果之NP-1496 siRNA，需大量經jetPEI轉染才可發現病毒抑制效果 (50-75% HA unit decrease)。H3N2 (A/Panama/1/68) siRNA之研究中十四段標的序列之轉染可見PA-1’序列最具有病毒抑制效果 (50% HA unit decrease)，PA-2、NP-3與PA-4’序列則亦於紅血球凝集測試中具病毒抑制效果，而較有效之shRNA質體共同轉染之組合則並無加成作用。PA-1’於病毒斑分析中亦可見抑制效果 (67% plaques decrease)。H1N1 (A/WSN/33) siRNA之研究中於MDCK-p69細胞株轉染，可見PA-1’與NP-1496序列於紅血球凝集測試中有部份病毒抑制效果 (50-75% HA unit decrease)。若以pseudotyped lentivirus與puromycin進行MDCK-p69細胞之感染與篩檢，則可將轉染效率提高至74%，而序列PA-1’與NP-3皆可見到較明顯之病毒抑制效果 (50-88% HA unit decrease)。shRNA序列之抑制效果與否與標的序列之3’端為stem或loop 結構較無明顯關聯。
結論： PA-1’為較有效抑制A/Panama/1/68, H3N2或A/WSN/33, H1N1之標的序列，其餘序列則出現效果分歧的結論，而更換環狀序列並無增進抑制效果之成效。shRNA expression cassette抑制病毒效果與質體轉染效率、細胞繼代數及轉染後感染之時間點有關，而lentivirus系統轉染之效率優於liposome系統。即使是鄰近序列，對於病毒抑制的效果也可能有很大的差別。標的基因3’端之二級結構與病毒抑制效果之間的關係仍需要更多序列分析。Background. Type A influenza virus infects 20% of global population every year, and genetic reassortment between different strains could cause pandemic outbreak. Vaccine is the only available strategy for type A influenza prevention, however, the identity between vaccine and circulating strain is only 52 to 82% in Taiwan. Anti-influenza drugs are not reliable due to highly mutant character of type A influenza virus. Therefore, a new strategy for prophylaxis and treatment for type A influenza virus should be studied. Small interfering RNAs (siRNAs), which target the more conserved sequence of type A influenza virus, could knockdown the gene expression and virus replication. Plasmid or lentivirus vectors carriage with short hairpin RNA cassette might more persistently express the shRNA and inhibit the virus.
Materials and Methods. The target genes (NS1 gene, PA gene and NP gene) of two type A influenza virus strains, A/WSN/33 (H1N1) and A/Panama/1/68(H3N2), are aligned for the siRNA target sequences. MDCK-ATCC and p69 cell lines are then transfected with quantitative shRNA plasmid, followed by influenza A virus infection. Pseudotyped lentivirus with shRNA sequence is used as an alternative tool for cell transduction. The viral load of supernatant are analyzed by hemagglutiation assay (HA assay), real-time PCR and plaque assay. If several potently inhibitory sequences could be found, the inhibitory effect of co-transfection is also studied.
Results. For MDCK-ATCC cell, the transfection efficiencies of jetPEI and Lipofectamine 2000 are 20-30% and 34%, respectively, which were inverse to the passage number. Large amount NP-1496 siRNA (500pmol) via jetPEI delivery is related to influenza virus inhibition (50-75% HA unit decrease). In H3N2 (A/Panama/1/68) shRNA study, PA-1’ is the most powerful sequence for influenza virus inhibition, which reveals 50% and 67% influenza virus decrease, respectively. PA-2,NP-3 and PA-4’ also have some inhibitory effects. The co-transfection reveal no synergistic effect. In H1N1 (A/WSN/33) shRNA study, PA-1’ and NP-1496 sequences could achieve 50-75% HA unit decrease after transfection to MDCK-p69 cell. The transfection efficiency could increase to 74% after pseudotyped lentivrus transduction and puromycin selection. PA-1’ and NP-3 sequences reveal more obvious influenza virus inhibition (50-88% HA unit and 57-91% plaques decrease). There is no relationship between the virus inhibition and secondary structure of 3’ end of target sequences in this study.
Conclusion. PA-1’ sequence is a more effective sequence in type A influenza virus inhibition. However, some sequences reveal diverse conclusion. No more effect could be achieved after changing the loop sequence of shRNA. The knockdown effect of shRNA plasmid is related to the transfection efficiency, cell passage number and timing of virus infection. The transfection efficiency is better in lentivirus system than in liposome system. The inhibition effect could be completely different between two nearby sequences. The relationship between secondary structure of 3’ end of target sequence and virus inhibition should be further surveyed.一、 中文摘要 1
二、 緒論 3
三、 研究方法與材料 9
四、 結果 15
第一部分、H1N1 (A/WSN/33) NP-1496 siRNA之病毒抑制實驗 15
第二部分、H3N2 (A/Panama/1/68) shRNAs之研究 15
第三部分、H1N1 (A/WSN/33) shRNAs之研究 17
第四部分、以lentivirus為載體之H1N1 (A/WSN/33) shRNAs之研究 18
五、 討論 20
六、 展望 28
七、 論文英文簡述 31
八、 參考文獻 41
九、 圖表 4
背景渦度下雙渦漩交互作用之水工實驗
No full text本文中所進行的水工實驗，是以一旋轉水槽作等角速度旋轉，其工作流體為水，經由在適當的類比條件下於旋轉水槽中產生二個類似於颱風渦漩流場，再由不同的渦漩產生方式比較雙渦漩相互之間的運動情形，並且經由改變不同的渦漩產生方式以創造出大而弱與小而強的不同渦漩，其渦度比要在六倍以上，半徑比大於二倍等，以嘗試是否可以在實驗室的水工模擬上產生出類似自然界中雙眼牆的現象。在流場的觀察上，吾人利用染料的施放以做定性的觀察，再藉由雷射光切頁及顯影細微顆粒的使用並配合CCD 攝影機及影像擷取卡來擷取吾人所要分析的渦漩流場影像，最後利用粒子軌跡測速法來對影像加以分析以得到流場定量的資訊。
在一適當的距離下，由吸取方式所產生的雙渦漩在渦漩產生的過程中即會因
為底部Ekman 層的影響而有一向內輻合的作用，所以兩渦漩在產生過程中即已互相受到干擾而並非兩獨立的系統。經由擾動所產生的二渦漩在渦漩剛形成時不會馬上相互吸引，反而是互相給對方一推力，使得兩渦漩初始會有一遠離的運動情形，且兩渦漩遠離後會再相互靠近的機會很小，故由攪動方式所產生的雙渦漩比較不容易會有合併的現象產生。但在β-plane 經由特定的條件下則可使得雙渦漩有合併的現象產生。經由攪動方式所產生的雙渦漩其渦度比可達到六倍以上，且可產生半徑較大的渦漩，但由於攪動方式所產生的雙渦漩不易合併，故經由數值模擬出的雙眼牆結構在水工實驗上則還未有類似的現象產生。目 錄
誌謝••••••••••••••••••••••••••••••••i
摘要••••••••••••••••••••••••••••••••ii
目錄••••••••••••••••••••••••••••••••iii
圖表目錄••••••••••••••••••••••••••••••vi
符號說明••••••••••••••••••••••••••••• xiii
第一章 緒論
1.1全文概述••••••••••••••••••••••••••••1
1.2研究動機••••••••••••••••••••••••••••2
1.3文獻回顧••••••••••••••••••••••••••••3
第二章 理論分析
2.1理論分析•••••••••••••••••••••••••••12
2.1.1旋轉座標••••••••••••••••••••••••• 12
2.1.2淺水方程與位渦守恆••••••••••••••••••••• 13
2.2 粒子追跡測速法原理••••••••••••••••••••••15
2.2.1影像的擷取•••••••••••••••••••••••• 15
2.2.2顆粒的辨識•••••••••••••••••••••••• 16
2.2.3 Voronoi影像方法••••••••••••••••••••••16
2.2.4粒子軌跡測速法•••••••••••••••••••••• 17
2.2.5 Voronoi 型態軌跡運算原則••••••••••••••••••19
第三章 實驗設備與實驗步驟
3.1實驗相關設備介紹••••••••••••••••••••••• 21
3.1.1旋轉平臺••••••••••••••••••••••••• 21
3.1.2旋轉水槽••••••••••••••••••••••••• 22
3.1.3渦漩產生機構••••••••••••••••••••••• 23
3.2攝影及週邊設備•••••••••••••••••••••••• 27
3.2.1雷射光源••••••••••••••••••••••••• 27
3.2.2導光系統•••••••••••••••••••••••••• 28
3.2.3顯影細微顆粒••••••••••••••••••••••• 28 3.2.4攝影及影像擷取設備•••••••••••••••••••• 29
3.2.5無線影音傳輸器•••••••••••••••••••••• 30
3.3流場顯影方法••••••••••••••••••••••••• 31
3.3.1染料注入法•••••••••••••••••••••••• 31
3.3.2雷射光切頁顯像法•••••••••••••••••••••• 32
3.4 動態平衡•••••••••••••••••••••••••••32
3.5雙渦漩產生實驗步驟•••••••••••••••••••••• 33
第四章 結果與討論
4.1由吸入方式產生雙渦漩之探討••••••••••••••••••36
4.1.1 強弱比固定下，改變不同的距離•••••••••••••••36
4.1.2 等距離下，不同強度比•••••••••••••••••••37
4.2 不同渦漩產生方式的比較••••••••••••••••••••39
4.3 由攪動方式產生雙渦漩之探討••••••••••••••••••41
4.3.1 攪動法所產生單一渦漩之基本性質••••••••••••••41
4.3.2 在β平面上雙渦漩行進路徑•••••••••••••••••42
第五章 結論與未來展望
5.1結論••••••••••••••••••••••••••••• 46
5.2未來展望••••••••••••••••••••••••••• 47
參考文獻 49
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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