1,720,974 research outputs found
Congenital heart defects in cattle
No full textCongenital heart defects (CHD) are cardiac diseases present at birth and a prevalence of 0.2% to 2.7% has been reported in cattle. How-ever, the real prevalence of bovine CHD could be underestimated because of the scarcity of surveillance programs and the low economical value of young animals, this leads the farmers to limit further diagnostic tests in calves suspected to have CHD. Moreover, many calves can have asymptomatic CHD that go undetected or die during the perinatal period before veterinary examination. The precise cause of CHD is not known in cattle and external teratogens or genetic factors can be implicated in the genesis of CHD. The use of selected sires for intensive breeding programs, especially in some of breeds with low population size, has increased the “inbreeding grade” that could be responsible for CHD. Congenital cardiac defects can be classified by various criteria and, in relation to the presence of cyanosis of the mucous membranes, they can be subdivided into cyanogenic or non-cyanogenic CHD. Ventricular septal defects, atrial septal defects and persistent ductus arteriosus are the most frequently reported non-cyanogenic CHD in cattle. Complex CHD such as conotrun-cal anomalies (tetralogy of Fallot, complete transposition of the great arteries and double-outlet right ventricle) are commonly described as cyanogenic CHD. Rare CHD such as malformations of atrioventricular valves, outflow tract obstructions and anomalies of vessels connected to the heart are less frequently diagnosed in the bovine species. This review aims to provide a summary of the most com-mon CHD reported in cattle with the iconographic support from the authors’ experience, offering thus an overview of which congenital anomalies should be considered during the evaluation of cattle suspected to have CHD. A precise diagnosis can be useful in cases with isolated defects, which can be associated with a favorable prognosis; likewise, it can be important an accurate and early diagnosis in cases with severe and complex malformations, often associated with a poor prognosis for long-term productivity and survival. This is of primary importance in order to avoid unnecessary treatments or animal suffering
Atrial fibrillation in two healthy Chianina cows
No full textAtrial fibrillation is a cardiac arrhythmia which frequently occurs in human and veterinary medicine. This arrhythmia has been reported in cattle and it is commonly recorded in animals affected by underlying cardiac diseases or in association with gastrointestinal disease, abdominal pain, metabolic diseases and electrolyte disturbances. Idiopathic atrial fibrillation has been also described in apparently healthy Holstein dairy cows with an incidence of 2.5%. The aim of this report is to describe for the first time the presence of primary and persistent atrial fibrillation in two Chianina cows without underlying diseases detected using routine diagnostic tests. The cows, apparently healthy, were examined for a disturbance of the heart rhythm in a farm of central Italy. Electrocardiographic examination confirmed the presence of atrial fibrillation with ventricular response rate of 80 bpm in both cows. Transthoracic echocardiography showed no structural heart diseases; results of the hematological and serum biochemical profile were unremarkable. No increase in troponin I concentration was revealed. Both cows were rechecked in a period of 14 months and no changes were observed at the physical and electrocardiographic examination. Both cows delivered a healthy calf during this period without calving difficulties or health problems. Based on the history, clinical findings and outcome, atrial fibrillation in both cows was considered primary and persistent in absence of underlying diseases. Being the heart rate in normal limits during the period of observation, treatments were not recommended. Atrial fibrillation can occur in healthy Chianina cows with no apparent underlying diseases and without compromising the reproductive performance. Evaluation of arrhythmias in cows can be a diagnostic challenge for veterinarians because of not-practical use of standard electrocardiographic machines, cables, and electrodes in field. However, new portable devices can be more easily available in farm and they can provide useful information for the diagnosis and prognosis in affected cattle
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
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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