1,720,958 research outputs found
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
Gonadotropin administration after gonadotropin-releasing-hormone agonist: a therapeutic option in severe testiculopathies
No full textOBJECTIVE:
To evaluate the effect of recombinant human follicle-stimulating hormone (FSH) plus human chorionic gonadotropin (hCG) on seminal parameters and pregnancy rate in severe testiculopathies after high FSH plasma concentrations have been suppressed.
DESIGN:
Prospective, controlled, randomized clinical study.
SETTING:
Infertility center at a university hospital.
PATIENT(S):
Eighty-seven men affected by severe testiculopathy.
INTERVENTION(S):
We treated 57 men with a gonadotropin-releasing hormone agonist (GnRH-a) and then with recombinant human FSH and hCG, and 30 patients did not receive any treatment. Seminal parameters and sperm aneuploidies were evaluated during and after the treatment period. Couples did not achieve a spontaneous pregnancy received assisted reproduction treatment.
MAIN OUTCOME MEASURE(S):
Seminal parameters, sperm aneuploidies, testicular cytologic analysis, FSH, luteinizing hormone, testosterone, inhibin B concentrations, and pregnancy rate.
RESULT(S):
After the therapy period, the treated group showed statistically significant improvement in sperm parameters and sperm aneuploidies. No changes were observed in the untreated group. A trend toward an increase in pregnancy rate also was observed among treated couples (cumulative pregnancy rates 31.6% treated vs. 20.0% untreated), although the increase was not statistically significant. The improvement of seminal parameters in the treated group allowed some patients to undergo in vitro fertilization-embryo transfer instead of intracytoplasmic sperm injection.
CONCLUSION(S):
Results from this controlled, randomized clinical trial show that FSH therapy improves sperm parameters in severe male factor infertility when endogenous high FSH plasma levels are suppressed. In cases of severely impaired testicles, a rational treatment of male infertility is mandatory to improve the outcome of assisted reproduction techniques
Retraction: Expression of phosphodiesterase type 5A in human spermatozoa and influence of its inhibition on motility and functional sperm parameters.
No full textHeat Shock Protein and Heat Shock Factor Expression in Sperm: Relation to Oligozoospermia and Varicocele
No full textPURPOSE:
Varicocele may be associated with normozoospermia or oligozoospermia. Much controversy still exists regarding the diagnosis, management and pathophysiology of spermatogenesis alterations associated with varicocele. The increased temperature induced by varicocele and stress in general may activate heat shock proteins and heat shock factors with a protective function in cells. We analyzed the expression of 5 heat shock proteins and heat shock factors in the sperm of men with normozoospermia and oligozoospermia with or without varicocele.
MATERIALS AND METHODS:
We performed a prospective study between June 2008 and February 2009 at an academic clinic in 117 consecutive patients with varicocele and 68 controls without varicocele. Four groups were based on the presence/absence of varicocele and normozoospermia/oligozoospermia. Subjects were studied by history, physical examination, scrotal Doppler ultrasound, semen analysis, reproductive hormone plasma levels and quantitative real-time polymerase chain reaction in RNA extracted from ejaculated sperm to analyze HSP90, HSPA4, HSF1, HSF2 and HSFY expression.
RESULTS:
Increased HSPA4, HSF1 and HSF2 were observed in the sperm of men with varicocele and in those with oligozoospermia. Levels were maximum when the 2 conditions were present. Increased HSP90 was observed in oligozoospermia cases independent of varicocele. HSFY was up-regulated only in patients with varicocele, especially those with normozoospermia.
CONCLUSIONS:
To our knowledge we describe for the first time the expression of different heat shock proteins and heat shock factors in ejaculated sperm. While some of these proteins are up-regulated in men with oligozoospermia and varicocele, HSFY is up-regulated only in the presence of varicocele and especially in men with normozoospermia. This suggests that it may be a molecular marker of an adequate or inadequate response to the damaging effect of varicocele on spermatogenesis
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
A possible association of a human tektin-t gene mutation (A229V) with isolated non-syndromic asthenozoospermia: Case Report
No full textAsthenozoospermia (AZS), characterized by grade A + B sperm motility (as in World Health Organization Guidelines) or =80% of examined spermatozoa involving axoneme microtubules and mitochondria. Moreover, the viability and mitochondrial function of sperm were altered in the patient with the A229V mutation. This is the first description of human pathology linked to a tektin-family gene, since only murine models are available for these genes
A possible association of a human tektin-t gene mutation (A229V) with isolated non-syndromic asthenozoospermia: Case Report
No full textAsthenozoospermia (AZS), characterized by grade A + B sperm motility (as in World Health Organization Guidelines) or =80% of examined spermatozoa involving axoneme microtubules and mitochondria. Moreover, the viability and mitochondrial function of sperm were altered in the patient with the A229V mutation. This is the first description of human pathology linked to a tektin-family gene, since only murine models are available for these genes
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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