1,721,087 research outputs found

    Three-Dimensional versus 2-Dimensional Endoscopic Third Ventriculostomy: Surgical Results of a Preliminary Comparative Study

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    Background: Three-dimensional (3-D) endoscopes have been widely used for a large variety of approaches in neurosurgical practice. However, in the last decade, 3-D scopes were barely used for ventricular surgery. In this study, we illustrated our preliminary experience with a 3-D endoscope for third ventriculostomy using new dedicated endoscopic equipment. Methods: Over a 12-month period, a high-definition 3-D endoscopic third ventriculostomy (ETV) was performed in 14 patients with obstructive hydrocephalus. Patients were followed prospectively and compared retrospectively with a matched group of 16 similar patients who underwent ETV with a standard 2-dimensional (2-D) endoscope. Surgical outcome and intra- and postoperative course were retrospectively reviewed. Results: 3-D ETV provided excellent surgical results, and no significant difference was shown in terms of outcome, complication, and length of hospitalization between the 2 groups. Moreover, operative time (minutes) was significantly shorter in the 3-D group than the 2-D ETV group (19.9 ± 4.8 vs. 22.9 ± 1.4, respectively; P < 0.05), and the use of the 3-D endoscope provided subjective improvements of depth perception, hand-eye coordination, and surgeon comfort. Conclusions: Our preliminary study clearly demonstrated the effectiveness of 3-D ETV and provided a significant reduction of operative time. Depth information from the 3-D scope appears to facilitate rapid and stable ETV maneuvers, representing a critical development that may become a valuable tool for neuroendoscopy

    Renal Function Replacement by Hemodialysis: Forty-Year Anniversary and a Glimpse into the Future at Hand

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    From its introduction in 1943 and until the late 1970s, hemodialysis (HD) has been a lengthy and cumbersome treatment administered by a few skilled physicians and technicians to a very limited number of terminal kidney patients. The technological innovations introduced over the years made HD a treatment administered and supervised by nursing personnel to a very large numbers of kidney patients, hopefully until recovery of kidney functions or kidney transplantation. In 2013, it is estimated that 2.250.00 kidney patients were treated worldwide, and their number is steadily increasing. Shortage of transplant kidneys and quality of current treatments has contributed to increasing the survival of HD patients. Today, it is not unusual to find patients who have been on HD for longer than twenty years. All this generated the feeling that performance of membranes and dialysis technology has reached its limit. Recently, the increasing economic burden of healthcare caused by people ageing and the increasing incidence of degenerative diseases (e.g. diabetes and cardiovascular diseases), and the economic crisis has pushed many governments and health insurances to cut resources for healthcare. The main consequence is that investments in research and development in HD have been significantly reduced. The question is whether there is indeed no need for innovation in HD.In this paper, it is discussed how the paradigm of HD has changed and what possibly are now the drivers for innovation in HD. A few ideas are proposed that could be developed by adapting existing technologies to the future needs of HD.</jats:p

    Going Beyond Counting First Authors in Author Co-citation Analysis

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    The 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

    Variations on the Author

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    “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

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    We 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
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