1,721,056 research outputs found
Machine learning for the identification of decision boundaries during the transition from radial to vertical growth phase superficial spreading melanomas
No full textThe objective of this study was to compute threshold values for the diameter of superficial spreading melanomas (SSMs) at which the radial growth phase (RGP) evolves into an invasive vertical growth phase (VGP). We examined reports from 1995 to 2019 of 834 primary SSMs. All the patients underwent complete surgical removal of the tumor and the diagnosis was confirmed after histologic examination. Machine learning was used to compute the thresholds. For invasive non-naevus-associated SSMs, a threshold for the diameter was found at 13.2 mm (n = 634). For the lower limb (n = 209) the threshold was at 9.8 mm, whereas for the upper limb (n = 117) at 14.1 mm. For the back (n = 106) and the trunk (n = 173), the threshold was at 16.2 mm and 17.1 mm, respectively. When considering non-naevus-associated and naevus-associated SSMs together (n = 834) a threshold for the diameter was found at 16.8 mm. For the lower limb (n = 248) the threshold was at 11.7 mm, whereas for the upper limb (n = 146) at 16.4 mm. For the back (n = 170) and the trunk (n = 236), the threshold was at 18.6 mm and 14.1 mm, respectively. Thresholds for various anatomic locations and for each gender were defined. They were based on the diameter of the melanoma and computed to suggest a transition from RGP to VGP. The transition from a radial to a more invasive vertical phase is detected by an increase of tumor size with a numeric cutoff. Besides the anamnestic, clinical and dermatoscopic findings, our proposed approach may have practical relevance in vivo during clinical presurgical inspections
Great saphenous vein versus expanded polytetrafluoroethylene graft in patients undergoing elective treatment of popliteal artery aneurysm with a posterior approach
No full textBackground: The aim of this study was to compare 30-day and 5-year outcomes of great saphenous vein (GSV) vs expanded polytetrafluoroethylene (ePTFE) graft in patients undergoing elective treatment of popliteal artery aneurysm (PAA) using a posterior approach. Methods: Between January 2010 and December 2023, a retrospectively maintained dataset of all consecutive asymptomatic PAAs who underwent open repair with posterior approach or endovascular repair in 40 centers was investigated. Of 971 cases, 525 patients were included in the present analysis. These were further divided into posterior approach with GSV graft (252; GSV group), and posterior approach with ePTFE graft (273; ePTFE group). Thirty-day outcomes were assessed and compared. During follow-up, survival, primary patency, secondary patency, freedom from reintervention(s), and amputation-free survival rates were compared between the two groups using log-rank tests. Univariate and multivariate Cox regression analyses were performed in the ePTFE group to find predictive factors of poor outcomes. Results: Two groups were homogeneous in terms of preoperative risk factors and morphological data. Median follow-up duration was similar (24 months [interquartile range [IQR], 10-36 months] GSV group vs 21 months [IQR, 7-47 months] ePTFE group; P =.123). At 5 years, there were no differences between the two groups in terms of survival (84.7% GSV group vs 86.1% ePTFE group; P =.097, log-rank = 2.756), secondary patency (94.9% GSV group vs 89.4% ePTFE group; P =.068, log-rank = 3.336), or amputation-free survival (99.1% GSV group vs 99.6% ePTFE group; P =.567, log-rank =.328). Five-year primary patency (89.5% GSV group vs 76.2% ePTFE group; P =.007, log-rank = 7.239) and freedom from reintervention(s) (92.8% GSV group vs 80.6% ePTFE group; P =.011, log-rank = 6.449) were significantly higher in the GSV group. Using multivariate analysis in the ePTFE group, factors compromising primary patency were patients on dialysis (P =.054; odds ratio, 3.641), and patients who were not on any preoperative antiplatelet therapy or anticoagulation (P =.019; odds ratio, 5.532), whereas none of the perioperative factors affected freedom from reintervention(s). Conclusions: GSV as graft guaranteed better primary patency with lower reinterventions rates at midterm follow-up after treatment of PAAs via a posterior approach. Patients on dialysis and who were not on any preoperative antiplatelet therapy or anticoagulation had lower patency rates
Acute medullary ischemia as clinical presentation of an intact infrarenal abdominal aortic aneurysm
No full textAbdominal aortic aneurysms (AAAs) are usually asymptomatic. Abdominal and/or low back pain are signs of rupture or impending rupture. We report the case of an 88-year-old man with unusual symptoms of clinical presentation for an AAA. He was admitted to our hospital with low back pain associated with bilateral lower extremity paresis. Examination revealed an abdominal pulsatile mass, and palpable peripheral pulses. Computed tomography angiography detected a 65-mm intact infrarenal AAA with neither signs of fissure or rupture nor lower extremity arterial disease. Magnetic resonance imaging demonstrated low-intensity signals at L1-L2 in the middle of the conus medullaris (acute medullary ischemia). The patient was managed conservatively with monoantiplatelet therapy, and low-weight-molecular heparin. Symptoms were resolved completely after 3 days. The final decision was to not treat the AAA
A new pericardium vascular prosthesis: mechanical behaviour, SEM analyses and clinical indications
No full textLow-fidelity simulators for the training of medical students in basic endovascular skills
No full textLetter to the edito
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
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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