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Isolation and characterization of the ATP-binding cassette (ABC) transporter system genes from loofah witches' broom phytoplasma
No full textMolecular Evolution and Related Defense Response of Pi-ta Gene in Wild Rice (Oryza rufipogon)
No full textPi-ta為水稻抗病（R）蛋白質，可專一性的辨識稻熱病病原菌的致病因子AVRpita，啟動抗病反應。此研究分析36個亞洲野生稻O. rufipogon的Pi-ta基因序列，經排列比較的結果，可以分成兩類基因群：H1及H2；藉由與外群非洲野生稻O. barthii比較，可推論H1衍生自H2。已知Pi-ta的第918胺基酸為決定對AVRpita的辨識專一性，由最大似然樹的結果，H1與水稻的Pi-ta分在同一個支序內，在第918胺基酸同樣為具有抗病性的丙胺酸，而H2則全都為不具抗病性的絲胺酸，以此胺基酸的差異分成抗病/不抗病主要的兩群進行相關的分析。H1以稻熱病病原菌IK81-25（具有AVRpita）接種，全為抗病，而H2有部分呈現不符合預期的結果，可能有不同的抗病（R）基因及致病因子（Avr）基因交互作用所造成。
由Pi-ta序列建構的基因樹結構、序列的變異明顯減小、高πnon/πsyn值及變異的相關地理分佈，推測野生稻的Pi-ta可能受到重複的選汰清除（recurrent selective sweep）及功能限制（functional constraint）的作用，而非單純族群擴張的結果。我們推論H1的為近期受到選汰清除作用，可能發生於早期稻米馴化的時期，稻熱病病原菌由小米轉移至野生稻或水稻後，因具有抗病的功能而被保留下來。而H2為更早期的選汰清除作用的結果，並受到功能限制的作用，而呈現出其低序列變異的特徵。
另外，我們運用微陣列分析具有Pi-ta基因的野生稻，在接種稻熱病病原菌後早期表現及抑制的基因。似接受器激酶（receptor-like kinase），細胞色素P450及WRKY轉錄因子為主要調節的基因類別；其它與抗病功能相關的基因，例如參與活性氧累積，訊息傳遞鏈及色胺酸的合成的基因亦有明顯的變化。未來需再進一步的實驗，來驗証這些廣泛調節基因功能及交互作用，這將有助於我們更了解水稻對抗生物逆境的機制。Rice blast disease is caused by the fungal pathogen Magnaporthe grisea. The resistant response is triggered by a physical interaction between the protein products of the host R (Resistance) gene Pi-ta and the pathogen Avr (Avirulence) gene AVRpita. The genotype variation and resistant/susceptible phenotype at the Pi-ta locus of wild rice (Oryza rufipogon), the ancestor of cultivated rice (O. sativa), was surveyed in 36 locations worldwide to study the molecular evolution and functional adaptation of the Pi-ta gene. The low nucleotide polymorphism in the Pi-ta gene of O. rufipogon was similar to that of O. sativa, but greatly differed from what has been reported for other O. rufipogon genes. The haplotypes can be subdivided into two divergent haplogroups named H1 and H2. H1 is derived from H2, with nearly no variation and at a low frequency. H2 is common and the ancestral form. The LRR domain has a high πnon/πsyn ratio and the low polymorphism of Pi-ta gene might cause primarily by recurrent selective sweep and constraint by other putative physiological function. Meanwhile, we provide data to show the amino acid, Ala-918, of H1 in the leucine-rich repeat (LRR) domain has close relationship with resistant phenotype. H1 might arise recently during rice domestication, and associate with the scenario of the blast pathogen host shift from Italian millet to rice.
To identify early induced and repressed defense genes involved in broad-spectrum resistance to rice blast, microarray is used to compare differentially expressed in AVRpita-resistant and -susceptible wild rice O. rufipogon. Receptor-like kinase (RLK), cytochrome P450, and WRKY transcription factor are the majority gene families induced. In addition, some genes that participate in ROS, signal transduction, and tryptophan pathway are discussed. Further functional validation and analysis of these genes will enhance our understanding of the molecular mechanism of broad-spectrum resistance in rice
The Relationship of Spindle Speed and Surface Roughness in Micromilling
No full text微元件在市場上的需求在近年來不斷增加，大量應用在航太、生醫、電子、通訊及汽車產業。而微銑削是生產微元件的一種製造方式，可以製造尺寸由幾十微米至厘米的微元件。論文使用直徑0.5mm、0.3mm兩種市售的微端銑刀和一般直徑10mm的端銑刀，加工6061鋁合金和S20C低碳鋼兩種金屬材料，以不同的切削速度加工後，利用光學輪廓儀量測表面粗糙度，經比較和觀察後發現直徑0.5mm及0.3mm的銑刀加工後之材料，表面粗糙度並未隨著主軸轉速的提升而顯著降低，而且發現切屑容易形成破片及粉末狀，並黏附在加工後的表面和刀具上，這些現象是一般傳統尺寸銑削不易發生的，針對這個問題本論文提出使用高壓空氣將切削液送入切削處的方法，可以改善加工後的表面粗糙度和刀具磨耗。Miniaturized components are increasing in demand for various application, such as aerospace, biomedical, electronics, communications and automotive. Micro-milling is a method to fabricate miniature devices and components with features that range from tens of micrometers to a few millimeters in size.his study presents an experimental investigation of the different tool diameter with 0.3mm, 0.5mm and 10mm of 6061 aluminum alloy and S20C steel in traditional milling and micro milling process. It is found that cutting under higher spindle speed results in worse surface roughness due to chip adhesion. The chip always turns into arc chip and powdery in the micro milling process. But these phenomena are not easy to occur in the traditional milling process. This paper proposes a method which send the cutting fluid to the cutting zone by using compressed air may improve the surface roughness and adhesive wear of the tool.中文摘要 I文摘要 II錄 III目錄 V號說明 X一章 緒論 1.1 研究動機 1.2 文獻回顧 6.3 研究目的 9.4 本文架構 9二章 相關理論 11.1 切削力學 11.2 銑削速度 14.3 進給速度 14.4 磨耗理論 15.5 表面粗糙度 20.5.1 表面組織定義 20.5.2 表面粗糙度的表示法 23三章 實驗規劃與實驗設備 27.1 實驗方法 27.2 實驗參數的選用 29.3 工件材料選用 31.4 實驗設備 31四章 實驗結果與討論 40.1 使用直徑10mm端銑刀加工Al6061鋁合金實驗結果 40.2 使用直徑0.5mm端銑刀加工Al6061鋁合金及S20C低碳鋼實驗結果 42.2.1 6061鋁合金銑削部分 42.2.2 S20C低碳鋼銑削部分 45.3使用直徑0.3mm端銑刀加工6061鋁合金實驗結果 48.4 以不同切削液加注方式輔助微銑削實驗 52.4.1 使用高壓空氣加切削液輔助銑削鋁合金實驗 52.4.2 輔助加工成效驗證實驗 54.4.3 使用高壓空氣加切削液輔助銑削S20C低碳鋼實驗 60五章 結論與未來展望 63.1 結論 63.2 未來展望 64考文獻 6
Molecular Evolution of the Pi-ta Gene Resistant to Rice Blast in Wild Rice (Oryza rufipogon)
No full textGoing 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
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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