1,721,020 research outputs found
The type of carbon source not the growth rate it supports can determine diauxie
No full textHow cells choose between potential carbon sources is a classic example of cellular decision-making, and we know that many organisms prioritise glucose. Yet there has been little investigation of whether other sugars are also preferred, blinkering our view of carbon sensing. Here we study eukaryotic budding yeast and its growth on mixtures of sugars with palatinose, an isomer of sucrose that cells catabolise with the MAL regulon. We find that yeast prioritise galactose over palatinose, but sucrose and fructose only weakly if at all, despite each sugar being able to support faster growth than palatinose. Our results therefore suggest that the decision-making is more than carbon flux-sensing. By using genetic perturbations and transcriptomics, we show that there is repression of the MAL genes via Gal4, the master regulator of the GAL regulon. Mechanistically, cells enforce their preference for galactose over palatinose through preventing runaway positive feedback in the MAL regulon. They do so both by repressing MAL11, the gene encoding the palatinose transporter, and by early expression of the isomaltases IMA1 and IMA5. By cleaving palatinose, these enzymes prevent its intracellular concentration becoming sufficient to induce further MAL expression. Our results demonstrate that budding yeast actively maintain a preference for carbon sources other than glucose and that such preferences have been selected by more than differences in growth rates. They imply that carbon-sensing strategies even in unicellular organisms are more complex than previously thought.README.txt - A description of how the data is gathered and explanations of the column headings. combined_data.csv - A text file of time-series data of optical density and fluorescence in long table format
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
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
Genetic Analysis of SCCmec in Methicillin-Resistant Staphylococci
No full text金黃色葡萄球菌是一種常見的病原菌，此菌為醫院院內感染之重要要病原菌之一，造成感染可自皮膚或傷口的感染至全身性的疾病，如肺炎、菌血症、心內膜炎、骨髓炎等，此外也可造成食物中毒。
MRSA (methicillin-resistant Staphylococcus aureus)為對甲氧苯青黴素(methicillin)具有抗藥性的金黃葡萄球菌。至目前的研究顯示，MRSA的產生，在於細菌獲得外來基因Staphylococcal Cassette Chromosome (SCCmec)，其中之mecA 基因會產生PBP2a，而對β—lactam抗生素產生抗藥性。除了mecA 基因外，SCCmec亦帶有許多不同的基因，而這些基因的多樣性，也造成了SCCmec的多樣性。MRSA所造成的院內感染，已經成了主要的公共衛生問題之一。MRSA長久以來一直造成臨床治療上的困擾。由於該菌不僅對各類β—lactam抗生素具有內在的耐藥性，而且常呈現出對其他類抗生素的多重耐藥性，引起臨床治療上的嚴重問題。由於MRSA之SCCmec基因構造相當複雜，而且不同地區也有差異，所以其分型的探討對於MRSA抗藥基因的研究相當重要。目前依照SCCmec的基因結構，大致可分成四型，分型的依據主要為mecI、mecR之有無，以及ccr基因之種類。
為了分析台大醫院分離之MRSA菌株基因特性，我們挑選了高、中、低抗藥性共59株MRSA進行SCCmec分型，分析SCCmec基因型與抗藥性高低之間的關係，並進而分析與S.epidermidis的之間的關連與相似性。
結果顯示，MRSA以及MRSE的SCCmec分型，有著相似的結果，主要有type III 和type IV兩型，而且高抗藥的菌株多為type III，而低抗藥的菌株則分布在type IV。The staphylococci are ubiquitous colonizers of human oranimal skin and mucous membranes causing a variety of syndromes. Among staphylococcal species, Staphylococcus aureus is the most pathogenic organism. Methicillin-resistant Staphylococcu is an increasingly important cause of hospital- and community-acquired infections throughout the world These strains carry the mecA gene, which encodes a modified penicillin-binding protein (PBP2a) that is responsible for resistance to β-lactam antibiotics. It is believed that methicillin-resistant Staphylococcus aureus (MRSA) has evolved from methicillin-susceptible S. aureus (MSSA) by the acquisition of a large genetic element known as the staphylococcal cassette chromosome mec (SCCmec).
To characterize SCCmec types of MRSA and methicillin-resistant S.epidermidis (MRSE) strains in our hospital, a total of 59 MRSA and 63 MRSE single-patient isolates selected from the collection between 1998 and 2003 at Nation of Taiwan university hospital were analyzed by genotyping.The methods included PCR, sequencing and dot blot analysis for the detection of presence or absence of variable or mobile elements previously shown to be associated with the mecA region. Typing of the 59 MRSA and 63 MRSE isolates demonstrated two major SCCmec types, type III and type IV. Correlation of resistance phenotypes and SCCmec types in MRSA and MRSE strains were also analyzed. Type III strains show higher level of resistance to oxacillin, and type IV strains show relatively lower level of resistance.英文摘要……………………………………………………1
中文摘要……………………………………………………3
序論…………………………………………………………5
實驗材料與方法……………………………………………10
實驗結果……………………………………………………23
討論…………………………………………………………27
實驗結果之附圖表…………………………………………30
參考文獻……………………………………………………4
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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