1,721,232 research outputs found
Singular radial solutions for the Lin-Ni-Takagi equation
Get PDFWe study singular radially symmetric solution to the Lin-Ni-Takagi equation for a supercritical power non-linearity in dimension N >= 3. It is shown that for any ball and any k >= 0, there is a singular solution that satisfies Neumann boundary condition and oscillates at leastktimes around the constant equilibrium. Moreover, we show that the Morse index of the singular solution is finite or infinite if the exponent is respectively larger or smaller than the Joseph-Lundgren exponent.Peer reviewe
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
Molecular Structure of Proline Containing Amyloid Fibrils Formed by Residues 127 to 147 of the Human Prion Protein
No full text普昂疾病（prion disease）為類澱粉樣疾病（amyloid disease）的一種，是會傷害腦神經細胞的感染性疾病，造成這種疾病的主要原因為結構有異變的普昂蛋白（prion protein, PrPSc）。利用電子顯微鏡測量PrPSc所形成的沉澱物，能夠觀察到很明顯的絲狀纖維結構。類澱粉樣蛋白纖維為一種非晶性的低水溶性物質，所以一般用於解出蛋白質分子結構的液態核磁共振與X光繞射都不適用，固態核磁共振技術為最合適的方法。在論文中，我們以人類普昂胜肽第127至147的多肽片段（Ac-GYMLGSAMSRPIIHFGSDYED-NH2, HuPrP127-147）所形成的類澱粉樣纖維來進行研究，利用固態核共振技術來解出其分子模型。HuPrP127-147普遍被認為是致病的主要胜肽片段之ㄧ，因此在普昂疾病的研究中是一個重要題目。除此以外，HuPrP127-147胜肽的中段含有一個脯胺酸殘基（P137），基於脯胺酸特別的空間構形，HuPrP127-147纖維的分子結構也是一個十分有趣的生物物理課題。我們成功的培養出HuPrP127-147的類澱粉樣蛋白纖維，並且利用ThT 螢光吸收、穿透式電子顯微鏡與原子力顯微鏡去確定其纖維分子的生成與形成的構形，我們量測出成熟的類澱粉樣纖維分子具有絞結（twist）的結構，絞結之間的長度約為70 至80 nm，高度約為3~4 nm。接著利用固態核磁共振去偵測其分子結構。我們由碳13訊號的線寬發現HuPrP127-147胜肽分子由第129號至142號殘基位置為結構性較高的區域，並且透過化學位移的偏移與背脊扭轉角psi的判定來確定此區域為b-strand的二級結構，再偵測出部分碳13之間的同核距離關係。實驗結果顯示，HuPrP127-147類澱粉樣蛋白纖維的基本結構為相互平行對齊的b-strand所組成，彼此之間的距離約為5~6 Å。由N端到C端的殘基訊號的強度發現， 以P137殘基位置為分界靠近C端的b-strand區域擁有較高動性結構。最後，使用紅外光吸收光譜觀測特定殘基位置的紅位移現象來偵測纖維分子中每條多肽之間的排列方式，實驗結果發現以P137殘基位置為分界靠近N端的b-strand區域的結構為cross-b的結構；靠近C端的b-strand區域雖有一定的結構性，但沒有背脊氫鍵鍵結，可能只有靠著支鏈之間的作用力來穩定其結構。Prion disease is a kind of amyloid disease, which is caused by the conversion of prion protein from its normal cellular form (cellular prion protein, PrPC) to the disease-specific form (scrapie prion protein, PrPSc). PrPSc exists in the form of amyloid fibrils, which are inherent insoluble and non-crystalline solids. Due to this reason, the detailed structural information of PrPSc is difficult to obtain by conventional techniques such as X-ray crystallography or solution-state NMR. It has recently been shown that solid-state nuclear magnetic resonance (SSNMR) is a particularly useful method for the structural elucidation of amyloid fibrils. In our study, amyloid fibrils are prepared by incubating the peptide fragment of human prion protein (HuPrP127-147), Ac-GYMLGSAMSRPIIHFGSDYED-NH2, in PBS at 37?C. HuPrP127-147 is believed to be an infectious fragment of the amyloidogenic region. In addition, HuPrP127-147 contains a proline residue, whose structure is highly constrained. Therefore, studying the fibrillar structure of HuPrP127-147 is an interesting topic of biophysics. Accordingly, ThT fluorescence spectra are obtained to confirm the fibril formation and the fibril morphology is studied by TEM and AFM. The fibrils have twist morphology and the twist period is about 70 to 80 nm The fibril height is between 3 and 4 nm. SSNMR measurements are carried out to probe for the molecular structure of the fibril samples. Our data show that the fibrils are formed by parallel in-registered alignment of peptides adopting b-strand conformation. In particular, each peptide constituting the fibrils has a b-strand region, viz. 129-142. With the proline (P137) as the boundary, the b-strand region near the N terminal (b1) has higher structural order than that near the C terminus (b2), which is associated with considerable dynamic motions. We also use FT-IR measurements to detect the vibrational dipole coupling in isotope-edited polypeptides. The results show that the b1 region conforms to the cross-b structure, but not the b2 region. We speculate that the b2 region is mainly stabilized by the side-chain-side-chain interactions.第一章 序論 1-1 普昂蛋白簡介 1-2 普昂蛋白結構異變 3-2-1 人類普昂蛋白 4-3 偵測PrPSc的分子結構 7-3-1 紅外線光譜 8-3-2 電子自旋光譜 10-3-3 固態核磁共振 11-4 研究動機 17-5 參考文獻 17二章 核磁共振基本原理 22-1 前言 22-2 核磁共振基本原理 22-2-1 核自旋（Nuclear spin） 22-2-2 核子自旋弛豫（T1, T2 relaxation） 24-2-3 NMR訊號的產生 26-3 固態核磁共振（Solid state NMR） 27-3-1 核自旋的交互作用 27-3-2 魔術角旋轉（Magic angle spinning, MAS） 31-3-3 偶極去耦（Dipolar decoupling） 33-3-5 交叉極化（Cross-polarization, CP） 33-3-6回耦（recoupling） 36-4 固態核磁共振對於偵測蛋白質二級結構的應用 39-4-1 二維譜簡介 39-4-2 二級結構的判定 40-4-3 背脊扭轉角的測定 43-5 偵測HuPrP127-147類澱粉樣纖維分子 46-6 參考文獻 46三章、合成與鑑定 48-1 材料與使用儀器 48-1-1化學藥品 48-1-2 使用儀器型號一覽表 50-2 胜肽樣品的製備 52-2-1 固相胜肽合成基本原理 52-2-2胜肽樣品的純化與鑑定 57-3 HuPrP127-147類澱粉樣蛋白纖維的備製 59-4 類澱粉樣蛋白纖維的鑑定 60-4-1 穿透式電子顯微鏡 60-4-2 原子力顯微鏡 61-4-3 ThT（Thioflavin-T） 螢光吸收 62-5 類澱粉樣纖維分子結構的鑑定 63-5-1 固態核磁共振 63-5-2 紅外光吸收光譜（FT-IR） 64-6 固態核磁共振光譜 65-6-1 13C-H交叉極化魔角旋轉光譜 65-6-2 13C-13C 同核相關性光譜 66-6-3 R-TOBSY的傳遞時間 68-6-4 fpRFDR-CT光譜 68-6-5 偵測普昂蛋白的背脊扭轉角psi 69-7 參考文獻 70四章 實驗結果與討論 72-1 胜肽的純化與鑑定 72-2 類澱粉樣纖維分子的鑑定 74-2-1 ThT螢光吸收 74-2-2穿透式電子顯微鏡 75-2-3 原子力顯微鏡 79-3 固態核磁共振實驗 81-3-1 13C-13C同核相關二維譜 81-3-2背脊扭轉角psi的測定 88-3-3 HuPrP127-147纖維分子的二級結構 92-3-3 R-TOBSY 傳遞時間 92-4 建構人類普昂胜肽片段127-147所形成類澱粉樣纖維分子模型 93-4-1 HuPrP127-147分子間結構（Intermolecular Structure） 93-4-2 FT-IR實驗 98-4-3 HuPrP127-147類澱粉樣纖維分子之動性結構 101-5 與SHPrP109-122所形成的類澱粉樣纖維分子做比較 103-6 參考文獻 104五章 總結與未來展望 107-1 論文總結 107-2 未來展望 10
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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