1,720,989 research outputs found
The role of the side-to-side isoperistaltic strictureplasty in patients with extensive Crohn’s disease: indications and results
No full textChromosome 5 allele loss in human gastric, ampullary and pancreatic carcinomas
No full textChromosome 5 allele loss is a genetic alteration occurring during the multistep
progression of colon carcinogenesis. To determine whether a similar genetic
alteration occurs in other gastrointestinal malignancies, the authors have
analyzed DNA extracted from freshly frozen normal and neoplastic tissue from
nineteen patients who underwent radical resections for gastric, ampullary and
pancreatic adenocarcinomas at the University of Chicago. Loss of heterozygosity
for alleles on the long arm of chromosome 5 was detected in tumor DNA compared to
normal tissue DNA from the same patient using restriction fragment length
polymorphisms (RFLPs). Eleven patients were informative using the restriction
endonuclease TaqI to generate RFLPs for chromosome 5 probes C11 P11 and pTP5E.
Loss of heterozygosity was found in one of eight informative gastric carcinomas
(12.5%) and in one of two informative ampullary carcinomas. The only informative
pancreatic adenocarcinoma was heterozygous. It is concluded that chromosome 5
allele loss occurs in a variety of gastrointestinal malignancies and suggest that
common genetic origins may underlie these different tumors
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Full text linkWe 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
Chromosome 17p Allelic Loss in Colorectal Carcinoma
No full textOBJECTIVE: To correlate allelic losses on chromosomes 5q, 8p, 17p, and 18q in
colorectal adenocarcinomas with histopathologic features of known prognostic
significance.
DESIGN: DNA was extracted from paired samples of 56 fresh-frozen colorectal
adenocarcinomas (one classified as Dukes' stage A, 22 as Dukes' stage B, 27 as
Dukes' stage C, and six as Dukes'stage D) and adjacent normal mucosa.
SETTING: Specimens were resected at the University of Chicago (Ill) and the
University of Padova (Italy) in 1991.
PATIENTS: Samples were obtained from consecutive patients.
INTERVENTIONS: Chromosomes 5q, 8p, 17p, and 18q were studied for loss of
heterozygosity by means of Southern hybridization blot analysis of restriction
fragment length polymorphisms, and the results were correlated with pathologic
tumor stage, degree of differentiation, and lymphatic and/or vascular
microinvasion.
RESULTS: Chromosomes 17p and 18q exhibited the highest frequency of loss of
heterozygosity (40.6% and 48.8%, respectively). Most of the allelic losses were
found in advanced tumors (60% in Dukes' stages C and D combined). A statistically
significant correlation was found between loss of heterozygosity on chromosome
17p and the presence of lymphatic and/or vascular microinvasion (P < .01,
Fisher's Exact Test).
CONCLUSIONS: There was a significant correlation between loss of heterozygosity
on chromosome 17p and the presence of lymphatic and/or vascular microinvasion in
colorectal adenocarcinoma, a known stage-independent negative prognostic risk
factor. Detection of loss of heterozygosity on chromosome 17p may identify a
group of patients who may benefit from more aggressive surgical and/or early
adjuvant therapy
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