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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
Ovarian activity during regular oral contraceptive use
No full textThe aim of this study was to assess whether during regular OC use ovarian activity might lead to ovulation, as assessed by ultrasound (US) evaluation of follicular growth and blood levels of 17-beta-estradiol and progesterone. A total of 51 healthy women with normal menstrual cycles (28 +/- 3 days) and no gynecological symptoms were recruited. A total of 22 patients were given a triphasic OC pill containing 35 mg ethinyl estradiol (EE) and 50 mg desogestrel (DSG) in the first seven tablets; 30 mg EE and 100 mg DSG in tablets 8 to 14, and 30 mg EE and 150 mg DSG in tablets 15 to 21; 29 patients received one of two OC pills, both containing 20 mg EE plus 150 mg DSG (15 patients) or 75 mg of gestodene (14 patients). A total of 86 cycles were monitored: 51 during the 3rd-4th cycle and 35 during the 6th-8th cycle of OC treatment. Follicular-like structures were observed in nine patients. The frequency of follicular-like structures was similar during the 3rd-4th cycle (9%) and during the 6th-8th cycle (11%). There was no relationship between follicular growth and blood levels of E2 and progesterone, which always appeared suppressed. In conclusion, the results of this study suggest that during OC use (even with low dose of ethinyl estradiol), a little ovarian activity may be present without ovulation
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
Repeated implantation failure at the crossroad between statistics, clinics and over-diagnosis
Get PDFThe most common definition of repeated implantation failure (RIF) is the failure to obtain a clinical
pregnancy after three completed IVF cycles. This definition, however, may lead to misuse of the
diagnosis. To disentangle this, we set up a mathematical model based on the following main
assumptions: rate of success of IVF constant and set at 30%; and RIF postulated to be a
dichotomous condition (yes or no) with a prevalence of 10%. On this basis, the expected cumulative
chance of pregnancy after three and six cycles was 59% and 79%, respectively. Consequently, the
false–positive rate of a diagnosis of RIF is 75% and 51%, respectively. Increasing the rate of
success of IVF or the prevalence of RIF lowers but does not make unremarkable the rate of false–
positive diagnoses. Overall, this model shows that the commonly used definition of RIF based on
three failed attempts in a standard population with good prognosis leads to over-diagnosis and,
potentially, to over-treatments
Effectiveness of sonohysterography in infertile patient work-up : a comparison with transvaginal ultrasonography and hysteroscopy
No full textObjective: The aim of this comparative study was to evaluate the accuracy of transvaginal ultrasonography (TVU), sonohysterography (SHG) with sterile saline solution compared to hysteroscopy in the diagnosis of intrauterine pathology in a population of infertile patients before an in vitro fertilization (IVF) program. Patients/Methods: 98 infertile patients with a mean age of 33.9 years (range 27-41) underwent TVU assessment and SHG with sterile saline solution immediately followed by hysteroscopy. Results: The clinical findings obtained by TVU, SHG and hysteroscopy were compared. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of TVU and SHG compared to hysteroscopy were calculated. The TVU sensitivity and specificity compared with hysteroscopy were 91 and 83% respectively. Using TVU, a 9.2% false positive rate (9 cases) and a 5.1% false negative rate (5 cases) were detected compared to hysteroscopy. The TVU PPV and NPV were 85.4 and 90% respectively. SHG yielded better results: sensitivity and specificity when compared to hysteroscopy were 98 and 94% respectively. The SHG PPV and NPV were 95 and 98% respectively. Accuracy of SHG was significantly better than TVU considering all intrauterine pathologies and polyps. Conclusion: In experienced hands, SHG is an easy, safe, and well-tolerated alternative to diagnostic hysteroscopy in the initial evaluation of uterine cavity infertile patients. Copyrigh
Comparison of GnRH agonists and antagonists in assisted reproduction cycles of patients at high risk of ovarian hyperstimulaton syndrome
No full textBACKGROUND: During IVF or ICSI cycles, ovarian hyperstimulation syndrome (OHSS) is a major problem. The aim of this prospective, multicentre, comparative study (using historical controls) was to assess the efficacy of a GnRH antagonist protocol in preventing OHSS in selected patients who had experienced OHSS or had been at risk of OHSS in their previous IVF/ICSI attempt. METHODS AND RESULTS: Patients underwent a new cycle where the same gonadotrophin protocol was used [same dose of recombinant FSH (rFSH)] but a different protocol was used for pituitary desensitization: cetrorelix 0.25 mg multiple-dose antagonist instead of GnRH agonist long protocol. Cetrorelix 0.25 mg was administered daily, starting when the leading follicle reached a diameter of 14 mm. In other words, rFSH was administered in the new cycle according to the dosage and the step-up or step-down modalities used during the previous cycle, independently of ultrasound findings and serum estradiol (E2) levels. Eighty-seven patients entered the study. Out of the 87 cycles involving GnRH agonists, 49 (56.3%) were cancelled and out of the 87 involving GnRH antagonists 28 (32.2%) were cancelled [McNemar's test; 95% confidence interval (CI) –35.8% to –11.2%; P 10 mm (Wilcoxon's test; Z=6.1; P < 0.001) and of E2 levels on the day of HCG administration (2538 versus 4322.4 pg/ml; P < 0.001) in the GnRH antagonist cycles versus GnRH agonist cycles. Twenty-nine patients had an embryo transfer in the first cycle (76.3% of oocyte retrievals) and 57 in the cycle using GnRH antagonist (96.6%). This 20.3% difference was also significant (Z-test; 95% CI 6.8–36.0%; P=0.003). After the antagonist cycles, 18 pregnancies (20.7 per initiated cycle; 31.6% per embryo transfer) were obtained. CONCLUSIONS: Although this study presents some limitations owing to the use of historical controls, our data show a favourable effect of GnRH antagonists in reducing the incidence of OHSS and the number of assisted fertilization cycles cancelled because of the risk of OHSS in high responder patients. As a consequence, GnRH antagonist plus gonadotrophin administration could also increase the percentage of oocyte retrievals and embryo transfers in this high risk group of patients
Sperm cryopreservation and reproductive outcome in male cancer patients: a systematic review
No full textThis systematic review of the literature reports on the use and effectiveness of sperm banking programmes for cancer patients. Thirty studies with 11798 patients were included. The aggregated rate of use of cryopreserved semen was 8% (95% CI 8 to 9%). A statistically significant correlation emerged between the mean and median duration of follow-up and the rate of use (R2 = 0.46; P = 0.03). The rate of patients discarding their frozen sample was reported in 11 studies. The aggregated rate was 16% (95% CI 15 to 17%). The rate of patients who used their frozen semen and achieved parenthood was reported in 19 papers. The aggregated rate was 49% (95% CI 44 to 53%). The rate of patients achieving parenthood with the use of frozen sperm is low and, from an economical perspective, the effectiveness of programmes of sperm banking might therefore be questioned. On the other hand, the low rate of patients discarding their frozen samples and the correlation between rate of use and duration of follow-up suggest that the calculated 8% rate of use may be an under-estimation and that cumulative rate of use may be substantially higher. Specific studies are, however, required to clarify this issue
Ovarian stimulation with low-dose pure follicle-stimulating hormone in polycystic ovarian syndrome anovulatory patients: effect of long-term pretreatment with gonadotrophin-releasing hormone analogue
No full textA randomised clinical trial was performed to evaluate the effect of a 3-month gonadotrophin-releasing-hormone analogue (GnRH-a) in one cycle of ovulation induction with low-dose pure follicle-stimulating hormone (pFSH) in patients with polycystic ovarian syndrome (PCOS) anovulation. Twenty patients with chronic anovulation due to PCOS were randomised to ovulation induction with pFSH administered in a low-dose schedule with (10 patients) and without (10 patients) a 3-month pretreatment with GnRH-a. Ultrasound scan only monitoring of follicular growth, evaluation of plasmatic oestradiol at the day of triggering of ovulation with human chorionic gonadotrophin 5,000 IU and evaluation of plasmatic progesterone 8 days after were the main outcome measures. Ovulation occurred in 9 patients treated with pFSH and in 2 patients treated with GnRH-a plus pFSH. Five pregnancies in the pFSH group and no pregnancy in the GnRH-a group were obtained. Five cycles were stopped due to multifollicular growth in the GnRH-a group and 1 in the pFSH group. Pretreatment with a 3-month administration of a GnRH-a did not improve the ovulation rate and pregnancy rate in PCOS patient ovulation induction with low-dose pFSH
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