1,720,972 research outputs found
Regulation of Cronobacter Sakazakii Apee Outer Membrane Esterase
No full textC. sakazakii bacterial infection is mainly observed in infants, where the primary source of the organism and the main vehicle for its transmission is rehydrated, powdered infant formula. The organism is also found in many plant materials such as cereals, wheat, corn, soy, rice, herbs and spices; in rats, and flies; and in other food products. To begin studying the possible roles of the outer membrane esterase ApeE in this organism, we have cloned the promoter for the C.sakazakii apeE gene and begun studying its regulation. First, we amplified the promoter region of the C.sakazakii apeE gene outer membrane esterase through the polymerase chain reaction (PCR) process, and then cloned the PCR fragments into the pRS550 vector where it drives expression of the gene for the easily assayed enzyme galactosidase. Second, we transfered the pRS550+PCR fragment reporter plasmid into strains of E. coli containing deletions of various regulatory genes, and the amount of galactosidase expressed from the C. sakazakii apeE promoter was measured. Our results showed that galactosidase expression in the rpoS mutant was reduced by about 50 fold compared to the wild type. This is different from the regulation of the homologous gene in the related bacterium Salmonella enterica where it is regulated by PhoB. Since RpoS regulates genes that are highly expressed when the bacterium enters stationary phase, we intend to confirm these results by studying expression of the C. sakazakii apeE gene during both exponential growth and stationary phase
Determination of the SIVmac Vif-Human APOBEC3B Interaction
Get PDFThe APOBEC3 family of enzymes are DNA cytosine deaminases, some of which restrict replication of HIV-‐1. This viral restriction is caused by deamination of cytosines to uracils in the viral cDNA, resulting in lethal mutation. HIV-‐1 counteracts this deamination by producing the protein Vif, which targets the restricting APOBEC3 enzymes for proteosomal degradation. Previous studies have demonstrated that HIV-‐1 Vif mediates degradation of APOBEC3D (A3D), APOBEC3F (A3F), APOBEC3G (A3G), and APOBEC3H (A3H). Other lentiviruses may also encode a Vif protein, however not all Vif proteins can degrade the same APOBEC3 proteins. For example, SIVmac (simian immunodeficiency virus that infects rhesus macaques) Vif was reported to mediate degradation of APOBEC3B (A3B), but not A3F. A3B does not restrict HIV, but is highly expressed in multiple cancers (bladder, cervical, lung squamous cell carcinoma, lung adenocarcinoma, head and neck, and breast) and is thought to contribute to tumor evolution. My goal is to determine the binding region between SIVmac Vif and A3B
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
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
Utilisation du ratio d’activité isotopique Y-92/Sr-92 pour la datation d’une récente libération radioactive
No full textThis study reports on an accurate assessment of zero time of certain nuclear events using Y-92/Sr-92 isotopic activity ratio. For a non-steady nuclear fission reaction, the dating is not possible. For the hypothesis of a nuclear explosion and for a release from a steady state nuclear fission reaction the zero times will differ. This assessment is fast, because we propose some constants that can be used directly for the calculation of zero time and its upper and lower age limits. The assessment is accurate because of the calculation of zero time using a mathematical method, namely the weighted least-squares method, to evaluate an average value of the age of a nuclear event. This was done using two databases that exhibit differences between the values of some nuclear parameters, namely LARA and ENDF.Cette étude porte sur une évaluation précise du temps zéro de certains événements nucléaires en utilisant le rapport d'activité isotopique Y-92/Sr-92. Pour une réaction de fission nucléaire non stationnaire, la datation n'est pas possible. Pour l'hypothèse d'une explosion nucléaire et pour une libération d'une réaction de fission nucléaire en régime permanent, les temps zéro (date de la fin de la réaction de fission) seront différents. La différence entre les temsp zéro calculés est également due à la variété des données nucléaires et radioactives dans des bases de données telles que LARA et ENDF. Ce travail propose quelques constantes utilisables directement pour le calcul du temps zéro et de ses limites d'âge supérieure et inférieure tout en tenant compte de la diversité des bases de données nucléaires. L'évaluation du temps zéro est plus précise à l'aide d'une méthode mathématique, à savoir la méthode des moindres carrés pondérés, pour estimer une valeur moyenne de l'âge d'un événement nucléaire. Cela a été fait en utilisant deux bases de données qui présentent des différences entre les valeurs de certains paramètres nucléaires, LARA et ENDF
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