1,720,959 research outputs found
Screw migration and oesophageal perforation after surgery for osteosarcoma of the cervical spine
Full text linkAbstract Background Even though internal fixation has expanded the indications for cervical spine surgery, it carries the risks of fracture or migration, with associated potential life threatening complications. Removal of metal work from the cervical spine is required in case of failure of internal fixation, but it can become challenging, especially when a great amount of scar tissue is present because of previous surgery and radiotherapy. Case presentation We report a 16 year old competitive basketball athlete who underwent a combined anterior and posterior approach for resection of an osteosarcoma of the sixth cervical vertebra. Fourteen years after the index procedure, the patient eliminated spontaneously one screw through the intestinal tract via an oesophageal perforation and developed a severe dysphagia. Three revision surgeries were performed to remove the anterior plate because of the great amount of post-surgery and post-irradiation fibrosis. Conclusions Screw migration and oesophageal perforation after cervical spine surgery are uncommon potentially life-threatening occurrences. Revision surgery may be challenging and it requires special skills
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
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
Effect of pedicle screw angles on the fracture risk of the human vertebra: A patient-specific computational model.
No full textThe assessment of a human vertebra’s stability after a screws fixation procedure and its fracture risk is
still an open clinical problem. The accurate evaluation of fracture risk requires that all fracture mechanical
determinants such as geometry, constitutive behavior, loading modes, and screws angulation are accounted
for, which requires biomechanics-based analyses. As such, in the present work we investigate the effect of
pedicle screws angulation on a patient-specific model of non osteoporotic lumbar vertebra, derived from
clinical CT images. We propose a novel computational approach of fracture analysis and compare the effects
of fixation stability in the lumbar spine. We considered a CT-based three-dimensional FE model of bilaterally
instrumented L4 vertebra virtually implanting pedicle screws according to clinical guidelines. Nine screws
trajectories were selected combining three craniocaudal and mediolateral angles, thus investigated through a
parametric computational analysis. Bone was modeled as an elastic material with element-wise inhomogeneous
properties fine-tuned on CT data. We implemented a custom algorithm to identify the thin cortical layer
correctly from CT images ensuring reliable material properties in the computational model. Physiological
motion (i.e., flexion, extension, axial rotation, lateral bending) was further accomplished by simultaneously
loading the vertebra and the implant. We simulated local progressive damage of the bone by using a quasi-static
force-driven incremental approach and considering a stress-based fracture criterion. Ductile-like and brittlelike fractures were found. Statistical analyses show significant differences comparing screws trajectories and
averaging the results among six loading modes. In particular, we identified the caudomedial trajectory as the
least critical case, thus safer from a clinical perspective. Instead, medial and craniolaterally oriented screws
entailed higher peak and average stresses, though no statistical evidence classified such loads as the most
critical scenarios. A quantitative validation procedure will be required in the future to translate our findings
into clinical practice. Besides, to apply the results to the target osteoporotic population, new studies will be
needed, including a specimen from an osteoporotic patient and the effect of osteoporosis on the constitutive
model of bone
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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