1,720,977 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
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
Protocol for a scoping review on the use of transcranial doppler in cardiac, aortic and carotid surgery
No full textCardiac, aortic, and carotid surgery are medical procedures at high risk for neurological complications; these include the occurrence of stroke, cognitive-behavioral alterations, disorders of consciousness, and focal neurological deficits [1–3]. The incidence of stroke in cardiac surgery is significant in about 1-5% of cases, whereas in aortic surgery is relevant in 7-10% of cases [4]. Perioperative stroke is also an important complication of carotid endarterectomy and its risk is around 2% [5].
The neurological complications following cardiovascular surgery are part of a series of alterations included in the definition of Post Operative Cognitive Dysfunction (POCD) [6], which have been classified into two types by the American College of Cardiology/American Heart Association: type 1 includes major focal neurological deficits, stupor, and coma; type 2 includes milder deficits, without focal deficits, such as delirium or decline in cognitive function in one or more domains [7]. The diagnosis of POCD requires evidence of a decline in cognitive function from preoperative to postoperative, exclusion of postoperative delirium, abrupt onset, temporal correlation with surgery, exclusion of other neurological conditions, present prior to surgery, that may explain the neurocognitive deficits, and adequate neuropsychological evaluation to test all cognitive domains involved in the neurological dysfunction (i.e. attention, language, memory, executive functions) which is carried out by means of specific neuropsychological tests [6].
The pathophysiological mechanisms underlying POCD have long been debated and many risk factors have been linked to its onset, such as advanced age, hypertension, atherosclerosis, a previous stroke and diabetes, but two of the main etiopathogenetic mechanisms considered are embolization and hypoperfusion [8,9]. There are two kinds of emboli, gaseous and solid; the latter in turn can be divided into macroemboli and microemboli. Gaseous emboli are related to macroscopic or microscopic air bubbles that may be present in the cardiopulmonary bypass (CPB) circuit [6], whereas solid emboli are related to parts of atheromatous plaques and cell aggregates, or inorganic parts of the CPB circuit, which may embolize into the central nervous vessels during surgical manipulation of the cardiovascular system [10]. Many Authors studied the correlations between microembolization and the occurrence of POCD; some findings reveal that the intraoperative embolic amount (measured with transcranial Doppler ultrasonography, TCD) correlates with the likelihood of postoperative cognitive decline [11,12], whereas other studies didn’t find such a correlation [13,14]. The nature of the emboli is also relevant in determining neurocognitive impairment: late POCD seems to depend more on gaseous microemboli than on solid ones [15]. As mentioned above, intraoperative TCD is a useful tool for the detection of emboli and it is possible, thanks to the multifrequency TCD instrumentation, to discriminate between solid and gaseous emboli [16].
Magnetic resonance imaging (MRI) is a useful tool for the detection of brain lesions due to cardiac surgery. Focal neurological deficits appear in almost 3% of patients undergoing cardiac surgery in the early postoperative period [17], however, some of these patients present with lesions on MRI without clinical evidence of neurological deficits; the limitations of this method are that it is not always possible to prove that the lesions revealed post-operatively are not pre-existing at the time of surgery, as a pre-operative examination is not always available for comparison [18]. There are many types of MRI sequences useful for studying post-operative brain lesions, including diffusion-weighted imaging (DWI), fluid-attenuated inversion recovery sequencing (FLAIR), proton density-weighted, and T2 [19–22]. Lesions visualized with FLAIR sequences remain evident indefinitely. At the same time, those detectable at DWI typically appear within 2 hours of the injury event and disappear after about 2 weeks, making it easier to identify any lesions that may have arisen in conjunction with cardiac surgery [19,20] and making them particularly suitable for the study of this type of lesions.
As neurological outcomes in cardiac surgery are still a clinical challenge, but their correlation with intraoperative embolic events and cerebral perfusion is still unclear, and as the use of TCD as intraoperative monitoring is not yet an established clinical practice in all cardiac surgery centers, this scoping review aims at an overview of the available direct and indirect evidence on the potential benefits of the use of intraoperative TCD, during cardiac and vascular surgery, on post-operative cognitive outcomes.
1. McKhann GM, Grega MA, Borowicz LMJ, Baumgartner WA, Selnes OA. Stroke and encephalopathy after cardiac surgery: an update. Stroke. 2006 Feb;37(2):562–71.
2. Kowalewski M, Malvindi PG, Suwalski P, Raffa GM, Pawliszak W, Perlinski D, Kowalkowska ME, Kowalewski J, Carrel T, Anisimowicz L. Clinical Safety and Effectiveness of Endoaortic as Compared to Transthoracic Clamp for Small Thoracotomy Mitral Valve Surgery: Meta-Analysis of Observational Studies. Ann Thorac Surg. 2017 Feb;103(2):676–86.
3. Raffa GM, Agnello F, Occhipinti G, Miraglia R, Lo Re V, Marrone G, Tuzzolino F, Arcadipane A, Pilato M, Luca A. Neurological complications after cardiac surgery: a retrospective case-control study of risk factors and outcome. J Cardiothorac Surg. 2019 Jan 25;14(1):23.
4. Stecker MM, Keselman I. Monitoring cardiac and ascending aortic procedures. Handb Clin Neurol. 2022;186:395–406.
5. Reddy RP, Karnati T, Massa RE, Thirumala PD. Association between perioperative stroke and 30-day mortality in carotid endarterectomy: A meta-analysis. Clin Neurol Neurosurg. 2019 Jun;181:44–51.
6. Uysal S, Reich DL. Neurocognitive outcomes of cardiac surgery. J Cardiothorac Vasc Anesth. 2013 Oct;27(5):958–71.
7. Eagle KA, Guyton RA, Davidoff R, Ewy GA, Fonger J, Gardner TJ, Gott JP, Herrmann HC, Marlow RA, Nugent W, O’Connor GT, Orszulak TA, Rieselbach RE, Winters WL, Yusuf S, Gibbons RJ, Alpert JS, Garson AJ, Gregoratos G, Russell RO, Ryan TJ, Smith SCJ. ACC/AHA guidelines for coronary artery bypass graft surgery: executive summary and recommendations : A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee to revise the 1991 guidelines for coronary artery bypass graft surgery). Circulation. 1999 Sep 28;100(13):1464–80.
8. Selnes OA, Gottesman RF, Grega MA, Baumgartner WA, Zeger SL, McKhann GM. Cognitive and neurologic outcomes after coronary-artery bypass surgery. N Engl J Med. 2012 Jan 19;366(3):250–7.
9. Hogue CW, Gottesman RF, Stearns J. Mechanisms of cerebral injury from cardiac surgery. Crit Care Clin. 2008 Jan;24(1):83–98, viii–ix.
10. Mackensen GB, Ti LK, Phillips-Bute BG, Mathew JP, Newman MF, Grocott HP. Cerebral embolization during cardiac surgery: impact of aortic atheroma burden. Br J Anaesth. 2003 Nov;91(5):656–61.
11. Pugsley W, Klinger L, Paschalis C, Treasure T, Harrison M, Newman S. The impact of microemboli during cardiopulmonary bypass on neuropsychological functioning. Stroke. 1994 Jul;25(7):1393–9.
12. Hammon JWJ, Stump DA, Kon ND, Cordell AR, Hudspeth AS, Oaks TE, Brooker RF, Rogers AT, Hilbawi R, Coker LH, Troost BT. Risk factors and solutions for the development of neurobehavioral changes after coronary artery bypass grafting. Ann Thorac Surg. 1997 Jun;63(6):1613–8.
13. Rodriguez RA, Rubens FD, Wozny D, Nathan HJ. Cerebral emboli detected by transcranial Doppler during cardiopulmonary bypass are not correlated with postoperative cognitive deficits. Stroke. 2010 Oct;41(10):2229–35.
14. Braekken SK, Reinvang I, Russell D, Brucher R, Svennevig JL. Association between intraoperative cerebral microembolic signals and postoperative neuropsychological deficit: comparison between patients with cardiac valve replacement and patients with coronary artery bypass grafting. J Neurol Neurosurg Psychiatry. 1998 Oct;65(4):573–6.
15. Zanatta P, Messerotti Benvenuti S, Valfrè C, Baldanzi F, Palomba D. The role of asymmetry and the nature of microembolization in cognitive decline after heart valve surgery: a pilot study. Perfusion. 2012 May;27(3):199–206.
16. Russell D, Brucher R. Online automatic discrimination between solid and gaseous cerebral microemboli with the first multifrequency transcranial Doppler. Stroke. 2002 Aug;33(8):1975–80.
17. Tarakji KG, Sabik JF 3rd, Bhudia SK, Batizy LH, Blackstone EH. Temporal onset, risk factors, and outcomes associated with stroke after coronary artery bypass grafting. JAMA. 2011 Jan 26;305(4):381–90.
18. Sun X, Lindsay J, Monsein LH, Hill PC, Corso PJ. Silent brain injury after cardiac surgery: a review: cognitive dysfunction and magnetic resonance imaging diffusion-weighted imaging findings. J Am Coll Cardiol. 2012 Aug 28;60(9):791–7.
19. Crisostomo RA, Garcia MM, Tong DC. Detection of diffusion-weighted MRI abnormalities in patients with transient ischemic attack: correlation with clinical characteristics. Stroke. 2003 Apr;34(4):932–7.
20. González RG, Schaefer PW, Buonanno FS, Schwamm LH, Budzik RF, Rordorf G, Wang B, Sorensen AG, Koroshetz WJ. Diffusion-weighted MR imaging: diagnostic accuracy in patients imaged within 6 hours of stroke symptom onset. Radiology. 1999 Jan;210(1):155–62.
21. Perkins CJ, Kahya E, Roque CT, Roche PE, Newman GC. Fluid-attenuated inversion recovery and diffusion- and perfusion-weighted MRI abnormalities in 117 consecutive patients with stroke symptoms. Stroke. 2001 Dec 1;32(12):2774–81.
22. Ebinger M, Galinovic I, Rozanski M, Brunecker P, Endres M, Fiebach JB. Fluid-attenuated inversion recovery evolution within 12 hours from stroke onset: a reliable tissue clock? Stroke. 2010 Feb;41(2):250–5
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
Protocol for a Systematic Review on the physiopathology of the neurogenic fever in animal models of subarachnoid hemorrhage
No full textSubarachnoid hemorrhage (SAH) is a very important cause of morbidity and unfavourable neurological outcome in patients admitted to intensive care unit. One of the main features of the course of these patients is the onset of a neurogenic fever, defined as an increase of the core body temperature > 38.3°C for 2 consecutive days [1], with onset within 72 hours from the occurrence of the bleeding [2] and which is not correlated with an infection source. Fever occurs in up to 70% of the patients affected by SAH and, among these, in the 50% of cases is not possible to find an infection source [3]. In patients with SAH, neurogenic fever, which is always associated with the presence of blood in the subarachnoid space [3] may favour vasospasm, contributing to worse neurologic outcome [1]. Currently, no treatment showed to be effective in SAH-associated neurogenic fever and, unlike septic fever, it is rarely controlled by treatment with usual antipyretic medications, such as cyclooxygenase-2 (COX-2) inhibitors, nonsteroidal anti-inflammatory drugs (NSAIDs), steroids or acetaminophen [4]. Our knowledge on this topic comes primarily from relatively small studies on animal models, therefore a systematic review pooling the results of such studies is appropriate. The primary aim of this review is to systematically search preclinical studies on neurogenic fever in animal models of SAH reporting data on its pathophysiology and prognostic factors. Secondary aims are: searching data in preclinical studies on the efficacy of any pharmacological therapies for neurogenic fever in animal models of SAH and to identify potential etiopathogenetic targets for future research.
References
1. Oliveira-Filho, J., et al., Fever in subarachnoid hemorrhage: relationship to vasospasm and outcome. Neurology, 2001. 56(10): p. 1299-304.
2. Hocker, S.E., et al., Indicators of central fever in the neurologic intensive care unit. JAMA Neurol, 2013. 70(12): p. 1499-504.
3. Fernandez, A., et al., Fever after subarachnoid hemorrhage: risk factors and impact on outcome. Neurology, 2007. 68(13): p. 1013-9.
4. Scaravilli, V., G. Tinchero, and G. Citerio, Fever management in SAH. Neurocrit Care, 2011. 15(2): p. 287-94
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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