1,720,983 research outputs found
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
Gamma Knife Radiosurgery for Tumors of the Endolymphatic Sac
Get PDFTumors of the endolymphatic sac are locally invasive temporal bone neoplasms. Radical surgical excision is the treatment of choice; however, the aggressive nature of these tumors can make total excision impossible. Recurrence is common in cases of incomplete resection. Gamma knife radiosurgery was used to treat two patients with primary tumors of the endolymphatic sac and one recurrent case. All three patients were alive at 75, 74, and 11 months, respectively, after gamma-knife treatment, and the tumors were either smaller or had not enlarged. None of the patients experienced radiation-related side effects during follow up. Gamma knife radiosurgery should be considered a treatment option for these surgically challenging tumors
Gamma knife radiosurgery for jugular foramen schwannomas
No full textJugular foramen schwannomas are very rare tumors. Advances in skull base surgery have led to more aggressive resection of these tumors, but surgery may associate with development of new neurological deficits. In this report, we analyze the long-term results for 17 patients with newly diagnosed or residual/recurrent jugular foramen schwannoma who underwent gamma-knife treatment. During a mean 64 months of follow-up, magnetic resonance imaging revealed reduced tumor size in 13 cases and no size change in four cases. The tumor growth control rate was 100% and only one patient had transient hoarseness. For patients who have small- to moderate-sized jugular foramen schwannomas, gamma-knife radiosurgery is associated with good tumor control and carries minimal risk of adverse radiation effects
PSA bouncing after external beam radiation for prostate cancer with or without hormonal treatment
No full textOBJECTIVES: The purpose of this study was to find out the frequency of PSA bouncing and the factors effecting PSA bounce after external beam radiation treatment (EBRT) with or without hormonal treatment (HT) for prostate cancer and to identify any possible relationship with biochemical control. METHODS: Between March 1997 and November 2000, 72 consecutive patients with clinically localised prostate cancer were treated by EBRT with or without HT. All patients had a pretreatment PSA level, at least six post-treatment PSA levels and minimum two years of follow-up. Median follow-up for all patients was 51 months (range 25-69 months). Median radiation dose given to the center of the prostate was 70Gy (range 63-74Gy). Fifty-nine patients (82%) received adjuvant HT with median duration of six months. PSA bounce was defined as a minimal rise of 0.4ng/ml over six months (monthly rise > or =0.07 ng/ml), followed by any decrease. Biochemical failure was defined in accordance with the ASTRO consensus guidelines. RESULTS: Seventeen patients (24%) experienced at least one PSA bounce. PSA bounces were more frequent in patients with T1-2 stage, pretreatment PSA <10 ng/ml, small field irradiation, radiation dose < or =70 Gy, PSA nadir > or =0.2 ng/ml and without HT. PSA bounce occurred in 54% of patients treated by EBRT only, and 17% of patients treated by EBRT and HT. Logistic regression model for multivariate analysis revealed the radiation field size as the only independent predictive factor for PSA bounce. Five-year biochemical control rates were 82% for non-bouncers and 88% for bouncers (p=0.5). CONCLUSIONS: PSA bouncing occurs in approximately a quarter of patients treated with EBRT with or without HT. It is associated with pretreatment and treatment characteristics, but we did not observe any relationship with biochemical failure
Medulloblastoma in adults: treatment results and prognostic factors
No full textPURPOSE: To investigate the treatment outcome and prognostic factors of adult medulloblastoma patients who received postoperative craniospinal irradiation (RT). METHODS AND MATERIALS: Between 1983 and 2000, 30 adult patients (17 men and 13 women, age >or=16 years, median 27, range 16-45) underwent postoperative RT. The median duration of symptoms was 2 months (range 1-9). The tumor location was lateral in 16 (53%). A desmoplastic variant was seen in 12 (40%). Tumor resection was complete in 20 (67%) and incomplete in 10 (33%). All patients received craniospinal RT. The median dose to the whole brain was 40 Gy (range 36-51), to the posterior fossa 54 Gy (range 49-56), and to the spinal axis 36 Gy (range 24-40). The median interval between surgery and the start of RT was 31 days (range 12-69), and the median duration of RT was 45 days (range 34-89). Ten patients (33%) received adjuvant chemotherapy. The median follow-up was 51 months (range 5-215). RESULTS: The 5- and 8-year overall survival and disease-free survival rates were 65% and 51% and 63% and 50%, respectively. Twelve patients (40%) developed relapse, with a median follow-up of 51 months. The posterior fossa was the most common site of relapse (6 patients). The median time to relapse was 26 months (range 4-78). Fifty percent of the relapses occurred after 2 years, 17% after 5 years. In univariate analysis, M stage and the interval between surgery and the start of RT were significant prognostic factors for disease-free survival. At 5 years, 70% of M0 patients were estimated to be disease-free, but none of the 3 M3 patients reached 5 years without recurrence (p = 0.0002). The 5-year disease-free survival rate for the patients whose interval between surgery and the start of RT was <3 weeks, between 3 and 6 weeks, and >6 weeks was 0%, 85%, and 75%, respectively (p = 0.002). The 5-year posterior fossa control rate for patients who received >or=54 Gy or <54 Gy to the posterior fossa was 91% and 33%, respectively (p = 0.05). CONCLUSION: The survival results for medulloblastomas in adults compare favorably with those in children. However, late relapses, lateral tumor location, and desmoplastic histologic features are more frequent in adults. Spinal seeding at presentation is a poor prognostic factor for disease-free survival. A minimal dose of 54 Gy to the posterior fossa is essential for adequate tumor control. The interval between surgery and the start of RT, which was found to be a significant prognostic factor, is an interesting issue that requires further study
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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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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