1,720,969 research outputs found
Controversies in the management of nonobstructive azoospermia
No full textThe fertility potential of patients with nonobstructive azoospermia (NOA) depends on sperm extraction from the tissue sample and then in vitro fertilization with intracytoplasmic sperm injection (IVF/ICSI). Unfortunately, there is no consensus regarding predictors that can identify nonobstructive azoospermic men with a potentially high yield at the time of sperm extraction. This article analyzes two competing approaches to these patients: noninvasive and invasive. The noninvasive approach, based on clinical, laboratory, and ultrasonographic investigations, excludes from IVF/ICSI a significant number of patients owing to errors in predicting the presence of sufficient intratesticular spermatozoa. The invasive approach, with available percutaneous or surgical testicular biopsy techniques followed by morphologic examination and or sperm recovery, permits many patients with NOA to receive a favorable prognosis and therapeutic trial. However, the available testicular biopsy techniques are so variable that their performance parameters cannot be adequately compared. As a result, any progress in optimizing these techniques must involve delineation of specific selection criteria for each NOA patien
Percutaneous biopsy of the testicle: a mini review with a proposal flow chart for non-obstructive azoospermia
No full textPercutaneous biopsy of the testicle: a mini-review with a proposal of flow chart for nonobstructive azoospermia.
No full textA general consensus on the role of testicular biopsy in non-obstructive azoospermia (NOA) is needed. This paper reviews and updates technical aspects and clinical performance of the percutaneous testicular biopsy techniques, in particular large-needle aspiration biopsy (LNAB), and proposes a flow chart for the management of NOA. The English literature and original data were reviewed or analyzed. Large-needle biopsy (LNB) includes large-needle cutting biopsy (LNCB) and large-needle aspiration biopsy (LNAB). LNCB usually requires scrotal incision for the insertion of relatively large needles. Fine-needle aspiration biopsy (FNAB) does not require surgical equipment or expertise, employs the smallest needles (23- to 20-gauge), and permits sperm cytologic detection. LNAB also does not require surgical equipment or expertise, employs needles of size from 20- to 18-gauge, is safe, and can be used for testicular histology and sperm recovery. An operative flow chart is proposed for the management of NOA in which FNAB, LNAB and open surgical biopsy are used for the optimal management of NOA
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
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