1,721,062 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
Adjuvant treatment of brain metastases
No full textWith an incidence of 15/10(5) in the general population, brain metastases constitute a serious, debilitating complication in cancer patients. The majority of those patients suffer from more than one metastasis, but up to 30% to 40% present with a solitary lesion. Whole-brain radiotherapy (WBRT) extends median survival from 1 to 2 months for treatment with steroids only, to 4 to 6 months in most series. However, long-term survival(>l-2 years) is observed in up to 10% of patients with favorable prognostic factors, such as solitary lesions, good Karnofsky performance status, and absence of extracranial disease. For those patients, individually optimized treatment is worthwhile. For good-prognosis patients with controlled extracranial disease, surgery in combination with postoperative WBRT should be considered, especially when fast relief of symptoms is mandated. For surgically inaccessible solitary lesions below a size threshold of approximately 30 ccm, stereotactic radiosurgery (RS), although never compared to surgery in a randomized fashion, seems to yield comparable results and is the treatment of choice for more than one lesion in appropriately selected patients. Nevertheless, a number of questions concerning the optimal treatment regimens for brain metastases remain. These mainly concern the radiation dose, need for a combination of RS and WBRT, relative timing of different treatment modalities, and maximum number of brain metastases that can reasonably be treated with RS when long-term progression-free survival is the peal. However, RS is definitely an excellent option for salvage and palliation in patients with short life expectancy, as it is simultaneously noninvasive and cost-effective, with short hospitalization times. (C) 2001 Wiley-Liss, Inc
Prognostic factors for brain metastases after whole brain radiotherapy - Data from a single institution
No full textPurpose: Prognostic factors for overall survival of patients treated for brain metastases with whole brain radiotherapy (WBRT) at a single institution were retrospectively evaluated, and the validity of the RTOG recursive partitioning analysis (RPA) for prognostic classes was assessed. Patients and Methods: The data of all. patients (n = 268) with brain metastases from solid tumors homogeneously treated between 01/1997 and 09/1999 at the University of Heidelberg, Germany, with WBRT without surgery or radiosurgery were reviewed. 13 different patient- and therapy-related variables were evaluated for prognosis. Second, a grouping of the study cohort was performed according to the RTOG RPA prognostic classes. Results: Median survival of the whole population after the start of WBRT was 3.8 months. The 1-year survival rate was 19%. Muk tivariate analysis revealed that only the Karnofsky performance status, control of the primary and no extracranial disease were independent prognostic factors for overall survival. These are also the main determinants of the RTOG RPA classes. Applying the RTOG RPA classes to the authors' data set revealed three subgroups with significantly different prognosis. Conclusion: Based on this analysis, prognostic factors for survival after WBRT in patients with brain metastases could be identified. A total of 19% (n = 44/232) survived greater than or equal to 1 year, whereas overall survival was poor. The potential value of the RPA classes in estimating the patient's prognosis could be confirmed
X-ray induced changes in immunostaining of proliferating cell nuclear antigen (PCNA) in V79 hamster fibroblasts
No full textBackground: Proliferating cell nuclear antigen (PCNA) ist a 36 kD protein that is involved in DNA-replication and -repair. For V79 hamster cells, a mutated p53 and a so-called "adaptive response", an improved radiation tolerance after pre-irradiation with low X-ray doses hours before definitive irradiation with higher doses have been reported. To better understand the role of PCNA after photon irradiation in vivo, using flow cytometry, we studied the immunochemical PCNA-staining in V79 cells after irradiation with 6-MeV photons with and without serum depletion and with and without low-dose pre-irradiation under different growth conditions. Material and Methods: Using V79 hamster cells, BrdUrd incorporation, total and DNA-bound PCNA were measured for exponential cells and for confluent cells at different times (up to 14 days) after reaching confluence. Cells were eith-er grown with medium containing 10% fetal calf serum (FCS) or 0.5% FCS. Six days after reaching confluence, cells were irradiated with 1 Gy land 8 Gy for non-serum-depleted cells) (6-MV photons, 2 Gy/min). Then, immunochemical PCNA-staining was measured by flow cytometry at 0, 30, 60 and 120 min after irradiation. For studying the adaptive response, exponentially growing cells and cells that were 6 days in confluence were pretreated with 0.01 Gy, reincubated for 5 h and then definitively treated with 1 Gy and harvested and processed as described above. Results: Four days after reaching confluence; DNA-bound PCNA and BrdUrd content were reduced to a minimum of <15% positive cells while total PCNA remained essentially unchanged. After irradiation with 1 Gy 6 days after reaching confluence, cells grown with 10% FCS showed a moderate but distinct transient increase in DNA-bound PCNA at 30 min after irradiation. After irradiation with 8 Gy, there was no clear increase at 30 min but a more distinct decrease at 60 min, implying that the increase might occur earlier in the time course at higher doses. Total cellular PCNA and BrdUrd uptake were constant during the first 2 hours after irradiation. In cells that were kept with serum depleted medium for 6 days after reaching confluence, total PCNA was reduced and no changes in either DNA-bound PCNA or BrdUrd-uptake were observed after irradiation. When cells were primed with a dose of 0.01 Gy 5 h before subsequent treatment with 1 Gy, neither for exponentially growing cells nor for those in confluence a significant difference in the detected amount of PCNA (total and DNA-bound) or BrdUrd was observed when compared to cells treated without a priming dose. Conclusions: The moderate X-ray induced DNA association of PCNA is indicative for ongoing DNA repair but appears to require serum stimuli. However, this p53-independent pathway involving PCNA does not seem to be the most relevant for survival in these rodent cells that tolerate much residual damage. Furthermore, no adaptive response for DNA-association of PCNA could be detected in V79 cells
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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