1,722,260 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
Effect of left ventricular function on long-term left ventricular pacing and sensing threshold
No full textBackground: The effect of left ventricular (LV) systolic function on the long-term left ventricular pacing and sensing threshold is unclear. Methods and Results: We studied the effect of LV ejection fraction (LVEF) on the LV pacing and sensing threshold in 56 patients (mean age: 70.2 ± 10.5 years) underwent permanent LV pacing using a self-retaining coronary sinus lead (Model 1055 K, St Jude Medical, USA). In 49 patients, the LV lead was implanted for conventional pacemaker indication (sick sinus syndrome = 14, heart block = 26 or slow atrial fibrillation = 9). The remaining 7 patients were implanted for congestive heart failure. The LV pacing and sensing threshold, and lead impedance were compared between patients with LVEF 40% (Group 2, n = 28) during implant and at 3-month follow up. The LV pacing lead was successfully implanted in all patients without any lead dislodgement on follow-up. At implant, Group 1 patients had a significant lower R wave amplitude, but similar LV pacing threshold and lead impedance as compared to Group 2. However, at 3-month follow-up, Group 1 patients had a significantly higher LV pacing threshold compared to Group 2 patients. There were no significant differences in the sensing threshold and lead impedance between the two groups. Furthermore, there was also a significant interval increase in LV pacing threshold in Group 1 patients (0.94 ± 0.12 V) after 3 months, but not in Group 2 patients (0.16 ± 0.08 V, p < 0.01). Conclusions: The results of this study suggest that the LV systolic function has a significant impact on the long-term LV pacing threshold. The long-term left ventricular pacing threshold in patients with left ventricular systolic dysfunction increased after implant and was higher than patients with normal left ventricular systolic function.link_to_subscribed_fulltex
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
The effect of diet intake on vascular function and therapeutic effect of cardiovascular medicine in patients with cardiovascular disease
No full textCardiovascular diseases (CVDs) remain to be the leading causes of morbidity and mortality in Hong Kong and worldwide. Among different modifiable risk factors, dietary pattern is on the major determinant for CVD and overall mortality. Other than pharmacological therapies for cardiovascular risk factors, such as hypertension, hyperlipidemia and diabetes, maintaining a healthy diet is a more sustainable method in general population to prevent CVDs. Current lifestyle intervention in the West countries focus on high intake of fruit and vegetables with more than 400g per day and limited saturated fats with less than 10% of energy, there is very limited data on impact of dietary pattern on CVDs in Chinese. Prior studies among Chinese in Hong Kong have shown that only half of the local population fell within these recommended ranges for fat, saturated fatty acid and cholesterol intakes.
Several different dietary patterns have been recommended for CVDs prevention based on: i) food groups, such as Mediterranean diet, the Dietary Approaches to Stop Hypertension (DASH) diet; ii) macronutrients: the low-carbohydrate diet, low glycemic index diet, very-low- fat diet and iii) nutrition or vitamin supplement. However, the effect of different dietary patterns based on modulations of food group, macronutrients and particular micronutrients on vascular structure and function in Chinese subjects is unclear. In the first part of this thesis, the relationships between different dietary pattern and surrogate markers of subclinical atherosclerosis and vascular function in different high risk populations for CVDs were investigated.
In Chapter 3, we compared the assessment of dietary pattern in Chinese using different tool, including Food Frequency Questionnaire (FFQ); Dietary Record; and Dietitian assessment. In this study, we demonstrated that suitable dietary assessments tools should be chosen for the assessment of different dietary pattern, according to characteristics of assessments.
In Chapter 4, the relationship between the fruit intake and subclinical atherosclerosis as measured by carotid intimal thickness (IMT) was investigated in patient with type II diabetes mellitus (DM). Our results showed that high fruit intake was associated with lower burden of carotid atherosclerosis, independent of level of vitamin intake in patients with type II DM.
In Chapter 5, we compared the impact of high carbohydrate diet on arterial stiffness between control subjects without CVDs and patients with high risk for CVDs. Our findings showed that high carbohydrate diet mainly affected patients with established CVDs, and their increased arterial stiffness was associated with an elevation of blood pressure.
In Chapter 6, we determined the effect of dietary vitamin intake on oxidative stress in patients with high risk of CVDs. In those high risk patients for CVDs, we demonstrated that increased dietary intake of vitamin A, beta-carotene and alpha tocopherol were associated with decreased oxidative stress, but these relationships were not observed in those control subjects without CVDs. It is likely attributed to the higher systemic oxidative stress levels in patients with high risk of CVDs.
On the other hand, food intake may also affect the clinical efficacy of cardiovascular therapies. In particularly, it has been well established that herbal intake which is commonly used by Chinese can affect the anticoagulant effect of warfarin on patients with non-valvular atrial fibrillation (AF). Thus, in this second part of the thesis, we investigated the effect of concomitant herbal intake on anticoagulation control in patients with non-valvular AF treated with warfarin. Our results showed that patients with AF treated with warfarin had limited knowledge on potential interaction between herbal substances in foods and warfarin, in which increased herbal substances intake significantly reduced the percentage time of anticoagulant effect within the therapeutic range. Moreover, a single section of education on knowledge of herbal ingredients did not improve their percentage time of therapeutic range for these patients.
In conclusion, these findings suggest that dietary pattern in Chinese might have significant impact of vascular function in patients with type II DM and high risk for CVDs. Moreover, the herbal substances in the diet among Chinese could have significant impact of the therapeutic effects in some of the cardiovascular medications, such as warfarin. Future clinical studies will be needed to confirm these potential beneficial effects of particular diet intake on vascular function in patients with high risks of CVDs as well as potential interaction between herbal substances in Chinese diet and cardiovascular medications.published_or_final_versionMedicineDoctoralDoctor of Philosoph
Novel insight into the mechanisms and treatment of ventricular tachyarrhythmias
No full textProgressive heart failure (HF) post myocardial infarction (MI) remains the leading cause of morbidity and mortality worldwide. Non-pharmacological interventions, including stem cell therapy and spinal cord stimulation (SCS), are emerging novel therapeutic approach to prevent or treat HF. Nevertheless, the potential impact of these interventions on the susceptibility for ventricular tachyarrhythmias (VT/VF), which are the most common cause of sudden death in HF patients remains unknown.
For stem cell therapy, sympathetic hyperinnervation as reflected by nerve spouting, lack of gap junction and immature electrophysiological phenotypes of the transplanted cells are potentially trigger and/or substrate for VT/VF after transplantation. Previous studies suggested that stem cell transplantation post-MI may induce cardiac nerve sprouting but their effects on gap junction expression are unclear. Furthermore, the effects of stem cell transplantation on cardiac nerve spouting and gap junction expression in chronic myocardial ischemia have not been addressed. In Chapter 3, we investigated bone marrow (BM) derived mononuclear cells (MNCs) and endothelial progenitor cells (EPCs) via direct intramyocardial transplantation in a porcine model of chronic myocardial ischemia. Our results showed that BM-MNCs or BM-EPCs transplantation was not associated with increased cardiac nerve sprouting, which might account for their low risk of proarrhythmias observed in clinical and experimental studies. In Chapter 4, we investigated the susceptibility to develop VT/VF after embryonic stem cells (ESCs) and their derived cardiomyocytes (ESC-CMs) transplantation in a murine model of MI. Moreover, the potential application of bioengineered ESC-CMs with over-expression of Kir 2.1 to reduce their susceptibility to induce VT/VF was also studied. Our results showed that transplantation of ESC or ESC-CMs reduced cardiac nerve sprouting and increased gap junction expression in the infarcted regions when compared with MI alone. The inducibility of VT/VF after ESC-CM transplantation was significantly higher than ESC transplantation or MI alone. On the other hand, over-expression of Kir2.1 improved the electrical maturation of ESC-CMs which significantly attenuated their vulnerability for VT/VF. These results suggested that the immature electrical phenotypes of ESC-CMs, rather than cardiac nerve spouting and changes in gap junction expression, plays an important role for proarrhythmias after stem cells transplantation, which can be eliminated by bioengineering of ESC-CMs.
Dysregulation of the autonomic nervous system with increased sympathetic tone and decreased parasympathetic tone has been well documented in HF progression, and is proposed to play an important role in arrhythmogenesis. In Chapter 5, we performed acute thoracic SCS at T1-T2 level in an animal model of ischemic HF (MI+HF) induced by MI and rapid ventricular pacing. Our results showed that acute SCS significantly increased left ventricular (LV) contractile function as determined by echocardiographic measurement of LV ejection fraction (LVEF) and invasive hemodynamic assessment of +dP/dt. Furthermore, myocardial oxygen consumption also significantly decreased during SCS without any change in serum norepinephrine level. Nevertheless, acute SCS failed to prevent spontaneous VT/VF provoked by prolonged (>2 minutes) acute myocardial ischemia.
Taken together, our results provide important insights into the potential mechanisms of proarrhythmias after stem cell transplantation as well as the acute beneficial effects SCS in ischemic HF.published_or_final_versionMedicineDoctoralDoctor of Philosoph
Relationship between psychological status and vascular function in subjects with and without cardiovascular diseases
No full textpublished_or_final_versionMedicineMasterMaster of Philosoph
- …
