1,721,005 research outputs found
Post-traumatic occipital intradiploic encephalocele
No full textBACKGROUND: Brain parenchyma herniation through a disrupted inner table into an enlarged diploic cavity with an intact outer table is described as intradiploic encephalocele. Intradiploic encephaloceles share common morphologic characteristics with expanding skull fractures and intradiploic arachnoid cysts. Herein, we describe a case of traumatic occipital intradiploic encephalocele.CASE DESCRIPTION: Cranial computed tomography of an 11-year-old boy revealed erosion of the inner table of the left side of occipital bone and expansion of the cranial diploe by a soft-tissue density with a gyral pattern. His medical history was positive for head trauma at the age of 3 years to the same region. Magnetic resonance imaging showed herniation of left occipital parenchyma with cystic encephalomalacic changes into the diploe.CONCLUSIONS: Intradiploic encephaloceles have different features compared with the classic encephalocele and can be considered as a variant of expanding skull fracture and intradiploic arachnoid cyst
Understanding the effect of effective metal surface area of flow diverter stent's on the patient-specific intracranial aneurysm numerical model using lagrangian coherent structures
No full textThe effective metal surface area (EMSA) of flow diversions plays an essential role in the occlusion mechanism inside the aneurysm since the value of EMSA determines the amount of blood flow into the aneurysm sac. In the present study, three different models of a flow diverter stent, namely FRED 4017, FRED 4038, and FRED 4539, were virtually placed at the aneurysm neck of a 52-years-old female patient to identify the effect of EMSA on stagnation region formation inside the aneurysm sac. Lagrangian coherent structures (LCSs), hyperbolic time, and particle tracking analysis were employed to the velocity vectors obtained from computational fluid dynamics (CFD). It is noticed that use of FRED 4017 stent with 0.42 EMSA value caused nearly 40% of the weightless blood flow particles (more than FRED 4038 and FRED 4539) to stay inside the aneurysm while only 0.35% of the blood flow was remaining inside the aneurysm sac when no stent was placed into the aneurysm site. Furthermore, hyperbolic time computations illustrated the formation of stagnation fluid flow zones that can be associated with the residence time of the blood flow particles. Lastly, the results of hyperbolic time analysis are in good agreement with digital subtraction angiography (DSA) images taken in the clinic a few minutes after a FRED 4017 implantation. (C) 2020 Elsevier Ltd. All rights reserved
Numerical study of a simplified cerebral aneurysm using a two different flow diverter stent modeling
No full textBu çalışma, 03-05, Ekim 2019 tarihlerinde İzmir[Türkiye]’de düzenlenen Medical Technologies Congress (TIPTEKNO) Kongresi‘nde bildiri olarak sunulmuştur.The effectiveness of clinical treatments in-stent modeling have been recently started to be analyzed using Computational Fluid Dynamics (CFD) technique. Particularly, variation of pressure loss with flow velocity is used to evaluate permeability and internal resistance coefficients of the flow diverter stents to describe the stent properties to CFD model. The velocity profile is described as pulsatile parabolic at the inlet, the pressure is described at the outlet to be 93 mmHg as a mean arterial pressure (MAP) in the present study. The results implied that there was no significant difference found between porous media and stent implantation of a flow diverter stent modelings based on the studied cases. However, fluid flow simulations indicated that use of 48 wires stent allows more blood flow passing into the aneurysm sac compared to the 72 and 96 wires stents for the studied geometry. Effect of pressure change in the vessel and shape factor of the artery was neglected.Biyomedikal Klinik Mühendisliği Derneğiİzmir Katip Çelebi Üniversitesi, Biyomedikal Mühendisliği Bölüm
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
Neuroimaging of first seizure in the adult emergency patients
No full textThe aim is to establish the role of head computed tomography (CT) and magnetic resonance imaging (MRI) in adults presenting to the emergency department (ED) with first-time seizure (FS) and to analyze the potential predictor variables for the adverse imaging outcome. We retrospectively reviewed the medical records of all adults who underwent cranial CT or MRI between January 1, 2011, and December 1, 2016, to an academic ED for FS. Patients were excluded if were under 18 years of age, had known recent intracranial pathology, known brain tumor or having a history of trauma. Important predictive variables to indicate pathology in either CT or MR scan in patients with FS were evaluated with logistic regression analysis. A total of 546 FS (293 men and 253 women; range, 18-81 years; mean, 47 years) were identified in patients receiving either cranial CT or MR scan. Of them, abnormal findings were observed in 22/451 (4.8%) patients on CT and 18/95 (18.9%) patients on MRI. Predictor variables of age greater than 50 years, focal neurologic deficit, hypoglycemia, and history of malignancy were identified on CT, whereas a history of malignancy, age greater than 50 years and focal neurological deficit were determined on MRI. Limiting neuroimaging to this population would potentially reduce head CT scans by 67% and would potentially reduce head MRI scans by 47%. Clinical suspicion should be heightened and the neuroimaging should be considered for advanced age, history of malignancy, hypoglycemia or focal neurological deficits in patients with FS
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
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