1,720,972 research outputs found
Short-term therapy for recurrent abortion using intravenous immunoglobulins: results of a double-blind placebo-controlled Italian study
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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
Vertical transmission of HIV-1: maternal immune status and obstetric factors. The European Collaborative Study.
No full textOBJECTIVE: To estimate the effect of maternal factors and events around the time of delivery on HIV-1 vertical transmission risk.
DESIGN: Prospective study.
SETTING: Twenty-two obstetric and paediatric clinics in seven European countries.
PATIENTS OR OTHER PARTICIPANTS: Mothers identified as HIV-infected before or at delivery and their children.
MAIN OUTCOME MEASURE: Paediatric HIV infection.
RESULTS: By November 1995, 1846 mothers with 1945 children had been enrolled. The vertical transmission rate was 16.4% (95% confidence interval, 14.5-18.3). Parity, maternal age, race, mode of HIV acquisition, injecting drug use and sex of infant were not statistically significantly associated with risk of transmission. Children delivered vaginally were more likely to be infected than those delivered by Caesarean section. However, in vaginal deliveries the procedures used, duration of ruptured membranes or length of second-stage labour were not related to transmission. Transmission increased almost linearly with decreasing CD4 cell count, but there was no such trend for CD8 cell count. Women with CD4 cell counts below 200 x 10(6)/l were significantly more likely to deliver early (chi 2 for trend, 14.02; P < 0.001). Very premature infants were at increased risk of infection, but after about 35 weeks gestation the transmission rate remained stable, with no increase in late pregnancy. This trend was confirmed after allowing for maternal CD4 cell count.
CONCLUSIONS: The rate of vertical transmission increases linearly with decreasing maternal CD4 cell count. Women with fewer than 200 x 10(6) CD4 cells/l have an increased risk of premature delivery, which would affect timing of interventions. The stable transmission rate after 35 weeks gestation suggests little acquisition of infection during late pregnanc
Risk factors for mother-to-child transmission of HIV-1.
No full textChildren born to women known to be infected with human immunodeficiency virus type 1 (HIV-1) before delivery were followed prospectively from birth in nineteen European centres. This analysis, encompassing the period end-December, 1984, to beginning-August, 1991, focuses on risk factors for mother-to-child transmission of HIV-1 infection. Rate of vertical transmission, based on 721 children born to 701 mothers more than 18 months before the time of analysis, was 14.4% (95% Cl 12.0-17.1%). Transmission was associated with maternal p24-antigenaemia and a CD4 count of less than 700/microliters. In a multivariate analysis, odds ratios of transmission were: 2.25 (95% Cl 0.97-5.23) in breastfed children vs never-breastfed children; 3.80 (1.62-8.91) in children born before 34 weeks' gestation; and 0.56 (0.30-1.04) in children delivered by caesarean section. Transmission was higher with vaginal deliveries in which episiotomy, scalp electrodes, forceps, or vacuum extractors were used, but only in centres where these procedures were not routine. On the basis of these results, HIV-infected women contemplating pregnancy should be counselled according to their immunological findings and, if they have p24-antigenaemia or a low CD4 count, warned of an increased risk of viral transmission. Caesarean deliveries may have a protective effect, although it is premature to recommend routine operative delivery. The mechanism for the higher infection rate in children born before 34 weeks' gestation is unclear, but could reflect inadequate passive or active immunity at that age, combined with substantial transmission during labour or delivery. The balance of evidence suggests that mothers with established infection can transmit HIV infection through breastmilk, although the relative importance of this route remains to be define
Sources of toxoplasma infection in pregnant women: European multicentre case-control study
No full textVariations 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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