1,720,958 research outputs found
Hémorragie sous-arachnoïdienne : lésion cérébrale, équilibre hydrique, pression intracrânienne et relation pression-volume
No full textChanges in osmolality and electrolyte concentrations are observed frequently in patients with subarachnoid haemorrhage (SAH). Intracranial pressure (ICP) plays a determinant role in the development of secondary brain damage following SAH and may be caused by haemorrhage itself, oedema formation and disturbance of cerebrospinal fluid (CSF) dynamics. The relationships among these factors are the aim of this investigation. In 17 comatose SAH patients, ICP was monitored through a ventricular catheter; serial of pressure-volume index (PVI) and CSF formation and reabsorption were performed. Arterio-jugular differences for oxygen and lactate were measured. The average ICP recorded for each 12 hour interval was 18.9 mmHg (SD = 5.9); mean cerebral perfusion pressure (CPP) was 75 mmHg (SD = 13); the lowest CPP value was 30 mmHg. Mean PVI was 22.7 mL (SD = 7.4), ranging from 5 to 36. Eleven patients however, showed a PVI less than 15 mL at some point during testing. Values of CSF dynamics indicated disturbances of CSF reabsorption in 11 cases. When the cause of ICP rise was identified in CSF disturbances, treatment was successful, even in case of reduced PVI. Mean C(a-v)O2, corrected for a PaCO2 of 40 mmHg, was 3.7 mL.dL-1 (SD = 1.1) ranging from the extremely low value of 0.2 to 6.8 mL.L-1. Three patients with extremely low C(a-v)O2 values showed a cerebral production of lactate and developed areas of ischaemia on the CT scan. Hyponatraemia, considered as a sodium plasma concentration of less than 135 mmol.L-1, was detected in seven patients. Hyponatraemia was treated by infusion of hypertonic sodium solutions. Mannitol (1 g.kg-1.d-1 in four doses) was infused if the sodium plasma concentration was not corrected by the former treatment or if ICP exceeded 20 mmHg. Treatment was aimed at preserving cerebral perfusion by providing adequate pre-load, low viscosity (Ht 30%) and sustained arterial pressure. Correction of hyponatraemia was therefore achieved more through hypertonic fluids infusion than by using diuretics
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
Pituitary Adenylate cyclase activating polypeptide increases intracellular cAMP levels in human nonfunctioning pituitary adenoma
No full textConcomitant evaluation of dehydroepiandrosterone sulfate and gonadal steroids in serum and cerebrospinal fluid from human male subjects.
No full textDispelling 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
[Arterio-jugular difference of oxygen and intracranial pressure in comatose, head injured patients. II. Clinical correlations]
No full textThe ICP monitoring is currently used in the treatment of the head injured patients in order to avoid dangerous increases of the pressure and critical reduction of cerebral perfusion pressure (CPP). The cerebral blood flow is dependent on the CPP and is kept constant, under normal circumstances, by autoregulation. When autoregulation is impaired or overwhelmed oxygen delivery becomes uncoupled to the metabolic needs of cerebral tissue: in such a condition the rate of oxygen extraction changes and the artero-jugular difference for O2 (AVDO2) reflects this change. The AVDO2 can be used as an estimate of the CBF and can detect a situation of hyperemia (low AVDO2) or ischemia (high AVDO2). In 224 comatose head injured patients the ICP was measured using ventricular or subarachnoid catheters: the CPP was continuously assessed and the outcome was evaluated six months after the trauma. In 45 patients the AVDO2 was studied and the data were corrected for a PaCO2 of 40 mmHg and investigated. The severity of the ICP is decisive for the prognosis and, accordingly, the number of times the CPP is below 60 mmHg plays a major role in the outcome. The mortality rate was 21% for the patients without ICP greater than 20 mmHg and 54% for the patients with severe increases in ICP. The mean values of AVDO2 were low, ranging around 4.6 vol%; only 4 patients showed some temporary evidence of ischemia, as assessed by an AVDO2 greater than 8 vol%.(ABSTRACT TRUNCATED AT 250 WORDS
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