1,721,026 research outputs found
Post-tetanic spontaneous spike activity in rat sympathetic neurons exposed to low potassium ion concentration.
No full textPreganglionic tetanic stimulation (30 sec at 50/sec) of rat superior cervical ganglia, performed in the presence of reduced external potassium concentration (0-1 mM), is followed by a long-lasting postganglionic afterdischarge which fails to appear if stimulation is repeated in normal (5.6 mM) postassium solution. Intracellular recordings revealed that tetanus is followed by 15-30 mV membrane hyperpolarization when the neuron is exposed to normal concentrations of potassium. Conversely, after the ganglion is soaked in low potassium, stimulation results in long-lasting depolarization of the nerve cell with the consequent appearance of spontaneous spikes. This effect is reversed on returing to normal external potassium. Spontaneous activity also occurs after antidromic activation of the cell. It is suggested that tetanus causes sodium loading of the neuron, which leads to stimulation of an electrogenic sodium pump. If potassium is available, the membrane will hyperpolarize, whereas depolarization and pacemaker activity ensues if external potassium is removed. The electrogenic sodium pump thus endows. the rat sympathetic neuron with a mechanism which enables it excitability to be controlled
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
Novel methods of management of trapped dormia baskets in the pancreatic and biliary ducts
No full textno abstract available; lette
Endotherapy of early onset idiopathic chronic pancreatitis: results with long-term follow-up.
No full textBackground: Idiopathic chronic pancreatitis that presents at age 35 years or younger has been classified as early onset type and is often characterized by chronic severe pain. Endotherapy, with drainage of the main pancreatic duct, can lead to control of pain if ductal hypertension is an important cause. Long-term results of endotherapy in patients with early onset idiopathic chronic pancreatitis are reported herein. Methods: This retrospective study consists of 11 patients (6 men, 5 women; mean age 24.2 years, range 16-34 years) treated endoscopically in a 6.5-year period. The indication for treatment was pain in all patients and all had a dilated main pancreatic duct on pancreatography. The objectives of endoscopic treatment were to obtain good drainage of the pancreatic duct and complete clearance of ductal stones. Results: Treatment was successful in all patients with no procedure-related mortality and with mild complications. Seven patients remained free of pain relapses after a mean follow-up of 78.3 months (37-116 months). Seven relapses of pain were recorded in the remaining 4 patients. Endoscopic retreatment was successful in all cases. The difference between the number of hospitalizations during the year before treatment (mean 2.2, range 1-9) and the year after (mean 0.3, range 0-2) was statistically significant (p < 0.01). Statistical significance was maintained at 3 and 6 years' follow-up. Conclusions: Endoscopic treatment could be regarded as the initial management of choice for patients with early onset idiopathic chronic pancreatitis
Treatment of "obstructive" pain by endoscopic drainage in patients with pancreatic head carcinoma
No full textObstruction of the main pancreatic duct with secondary upstream ductal hypertension is one cause of pain in patients with pancreatic cancer. Pancreatic endoscopic stenting and decompression of the pancreatic duct have been effective in the treatment of pain secondary to chronic calcifying pancreatitis and in one case of pancreatic cancer. We describe eight patients with unresectable cancer of the pancreatic head associated with upstream dilatation of the pancreatic duct and severe pancreatic ''obstructive''-type pain (correlation with meals and pain radiation to the back) in which a pancreatic stent was inserted across the neoplastic stricture. No mortality was associated with the procedure. All patients but one were free of pain within 48 hours after endoscopic pancreatic stenting, and all discontinued narcotics. Mean survival time was 165.5 days (range, 26 to 575 days). Six patients were still without symptoms, whereas two had a painful relapse a few days before death. No clinical evidence of pancreatic clogged stent was observed during follow-up. Endoscopic pancreatic drainage is a safe and effective way of controlling cancer pain in selected cases and should be considered as a further therapeutic option in these patients
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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