1,721,060 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Clinical Database of Upper Gastrointestinal Cancer -A Window to the Real World
No full textPatient characteristics, tumor characteristics, treatment-related information, and treatment outcomes are the main types of data currently collected by clinical databases on upper gastrointestinal cancer in the Netherlands. These data comprehensively cover the information that medical professionals are concerned with before and after patient treatment. It may help clinicians and policymakers understand the characteristics of the patient populations in the real world, the treatments they receive, and their treatment outcomes. Furthermore, it can aid medical experts in making targeted interventions in real-world medical practices, ultimately helping to improve the prognosis of upper gastrointestinal cancer patients. In Part I, the experience of the DUCA database in registering and maintaining a high-quality upper gastrointestinal cancer clinical database over the past decade was evaluated, with the intention of providing a reference for the construction of clinical databases in other countries or populations. In Part II, the upper gastrointestinal cancer clinical databases were used to generate evidence that may improve cancer care management in the real world. In Part III, the upper gastrointestinal cancer clinical databases were used to generate evidence that may influence surgeons' treatment decisions
Laparoscopic versus open gastrectomy for gastric cancer
No full textGeneral introduction and thesis outline
Gastric and esophageal cancer are the third and sixth more common causes of cancer-related death worldwide. In addition, the incidence of adenocarcinoma of the proximal stomach, gastroesophageal junction (GEJ) and distal esophagus is increasing, especially in Western populations. Unfortunately, only slightly over 50% of patients are diagnosed with potentially curable disease. Treatment with curative intent generally consists of surgical resection and chemo(radio)therapy. However, this treatment can lead to major morbidity and less than 40% of patients undergoing this treatment are cured. In addition, for the majority of patients, the current optimal treatment is relatively similar. Ultimately, to improve outcomes, treatment should be further tailored to the individual patient. The first aim of this thesis was to compare the two most important approaches of curative surgery for the relatively common gastric adenocarcinoma: laparoscopic versus open gastrectomy (part I). The second aim of this thesis was to evaluate treatment for less common subtypes of gastroesophageal cancer and treatment in patients at high risk for postoperative complications, to work towards a more personalized treatment of gastroesophageal cancer (part II).
Conclusion
Results from the multicenter randomized LOGICA-trial, performed in a Western population with mainly locally advanced gastric adenocarcinoma, demonstrated that postoperative complications, postoperative recovery, quality of life and oncological efficacy were comparable between laparoscopic and open gastrectomy. In laparoscopic gastrectomy, adequate pain control was achieved, generally without epidural analgesia. In addition, fewer patients used oral opioids at discharge, compared to the open gastrectomy. Differences in costs were limited between both treatments, though they might slightly favor open gastrectomy. These results support centers to choose, based upon their own preference, whether or not to (de)implement laparoscopic gastrectomy as an alternative to open gastrectomy.
Three nationwide retrospective studies were performed in patients with less common subtypes of gastroesophageal cancer: diffuse type carcinoma (including SRCC), (MA)NEC and gastroesophageal cancer with hepatic or pulmonary oligometastases. The results provide insights that can help guide treatment decisions at multidisciplinary tumor boards.
Two new clinical trials were designed and initiated as part of this thesis. The CARDIA-trial includes patients with Siewert type 2 GEJ cancer and the ISCON-trial includes patients with esophageal cancer selected on preoperative CT-scan to be at high risk for postoperative morbidity. Once completed, the results will help guide and further improve surgical treatment strategies for these patients
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
Advances in Gastric and Gastro-Esophageal Junction Surgery for Cancer
No full textChapter 1 – Introduction Gastric cancer is conventionally treated by means of open distal or total gastrectomy. The open surgical approach is associated with high morbity and long postoperative hospital stay. Minimally invasive surgery is upcoming for gastric cancer, since promosing results in the treatment of other abdominal diseases were booked. This thesis consists of 2 parts. In the first part the value of laparoscopic gastrectomy is described. In the second part the surgical treatment of tumors located at the gastro-esophageal junction is evaluated. These tumors are located at the transistional area between the esophagus and stomach and are therefore difficult to treat.
PART 1 – GASTRIC CANCER SURGERY
Chapter 2 In this systematic meta-analysis of comparative cohort studies the short-term outcomes of laparoscopic total gastrectomy versus open total gastrectomy in the treatment of gastric cancer were evaluated. Laparoscopic total gastrectomy was associated with reduced blood loss, lower short-term complication rates, and quicker functional recovery, at the price of a longer operating time. The included studies did not elaborate on oncologic outcome, long-term survival, or quality of life.
Chapter 3 This international cross-sectional survey revealed the current preferences in gastric cancer surgery. Members of the International Gastric Cancer Association filled in a web-based questionnaire about surgical techniques and approaches. The majority (79%) of respondents performed >21 gastrectomies per year. Open gastrectomy was preferred over laparoscopic gastrectomy (distal: 35% for early and 91% for advanced cancer; total: 52% for early and 94% for advanced cancer). Resection of the greater omentum was favored by the majority (89%) of respondents. A Roux-en-Y reconstruction with a jejunal pouch was preferably performed after total gastrectomy by a minority of respondents (17%). Thus far, as a reflection of the current practice, the minimally invasive techniques have not been generally implemented in clinical guidelines.
Chapter 4 In the UMC Utrecht cohort of patients with an identified germline ecadherin-1 (CDH1) mutation, prophylactic laparoscopic total gastrectomy was performed to eliminate the high risk of developing diffuse gastric cancer. The median operative time was 4:19 (3:15-6:03) hours and the median blood loss was 200 (20-400) ml. Median length of hospital stay was 10 (7-27) days. The 60-day mortality rate was 0%. Multiple foci of intramucosal diffuse gastric signet ring cell carcinoma were found in the resection specimen of 9/11 (82%) patients. All resections were microscopically radical. Enhanced postoperative recovery and reduced surgical trauma may especially be relevant to patients with a germline CDH1 mutation, since they have a higher life expectancy than patients with actual gastric cancer.
Chapter 5 Laparoscopic gastrectomy was performed in our cohort of Western European patients with predominantly locally advanced gastric cancer. The median intraoperative blood loss was 305 (30-2700) milliliters. The median postoperative hospital stay was 11 (5-91) days. The 30-day mortality was 4.3%. A radical resection was achieved in the vast majority of patients (90%). The median number of dissected lymph nodes was 17 (2-62). We demonstrated that laparoscopic gastrectomy can safely be performed in Western European patients with advanced gastric cancer and meets the oncologic standard.
Chapter 6 Omentectomy additional to gastrectomy is considered to be the standard surgical technique in the curative treatment of patients with resectable gastric cancer. In our prospective series of patients undergoing gastrectomy the greater omentum was marked during operation and pathologically analyzed to evaluate the presence of omental lymph nodes, tumor deposits and patterns of lymphatic spread. The omental lymph nodes contained metastases in 1 (2%) patient with stage IB gastric cancer. Omental tumor deposits were found in 4 (8%) patients stage IB-IIIA, of which 3 underwent perioperative chemotherapy. No significant differences in 1-year overall survival (p=0.106) and 1-year disease-free survival (p=0.258) for patients with and without omental lymph node metastases or tumor deposits were found. No predictive factors for omental tumor involvement could be identified. Therefore, omentectomy should be the standard in gastrectomy for all gastric cancer patients.
Chapter 7 In order to evaluate the laparoscopic gastrectomy compared to open gastrectomy in a large national setting a non-blinded, multicenter, prospectively randomized controlled superiority trial was designed. Patients (n=210) with resectable gastric cancer will be enrolled. The primary outcome is postoperative hospital stay (days). Secondary outcome parameters include postoperative morbidity and mortality, oncologic outcomes, readmissions, quality of life and cost-effectiveness. It is hypothesized that the functional recovery is faster in the laparoscopic group. Also, it is expected that laparoscopic gastrectomy will be associated with a lower postoperative morbidity, less readmissions, higher cost-effectiveness, better postoperative quality of life, with similar mortality and oncologic outcomes, compared to open gastrectomy.
Chapter 8 A major complication of gastrectomy is leakage of the esophagojejunostomy. Sealing the anastomosis with a fibrin patch (TachoSil) containing a human fibrinogen and thrombin, may improve mechanical strength of the anastomosis. A feasibility study of 15 patients with an esophageal anastomosis was performed. The sealant patch could be applied successfully in all patients. A median of 2 (1-6) attempts were necessary to reach successful application. The median duration was 7 (3-26) minutes before successful application was accomplished. In patients that underwent total gastrectomy, the patch was folded into a harmonica shape and wrapped around the esophagojejunostomy.
PART 2 – GASTRO-ESOPHAGEAL JUNCTION CANCER SURGERY
Chapter 9 Adenocarcinomas of the Gastro-Esophageal Junction (GEJ) are located at the transition zone between the esophagus and the stomach. The optimal surgical treatment of patients with this type of cancer has not been established yet. In a systematic review cohort studies comparing gastrectomy versus esophagectomy were evaluated. Radical resection rates varied between 72–93% for esophagectomy and 62%–93% for gastrectomy. Morbidity was 33–39% after esophagectomy versus 11–54% after gastrectomy. The 30-day mortality ranged between 1.0–2.3 after esophagectomy and 1.8–2.7% after gastrectomy. At 6 months after surgery, health-related quality of life was higher after total gastrectomy than after esophagectomy. The 5-year survival rates varied between 30–42% for esophagectomy and 18–38% for gastrectomy, but were not significantly different. In the selection of the most optimal surgical strategy, it is important to choose a surgical procedure that allows for radical resection of the GEJ tumor with dissection of adjacent lymph nodes. If both surgical strategies are deemed possible, a gastrectomy appears to offer the best long-term quality of life perspective.
Chapter 10 To evaluate the international preferences in the surgical treatment of GEJ tumors a survey was performed amongst surgical members of the International Society for Diseases of the Esophagus, the World Organization for Specialized Studies on Disease of the Esophagus and the International Gastric Cancer Association. The preferred surgical approach for Siewert type 1 tumors (5-1 cm proximal of the GEJ) was esophagectomy in 93% of respondents, whereas 6% favored gastrectomy and 3% combined a distal esophagectomy with a proximal gastrectomy. For Siewert type 2 tumors (1-2 cm from the GEJ) an extended gastrectomy was favored by 66% of respondents, followed by esophagectomy in 27% and total gastrectomy in 7%. Siewert type 3 tumors (2-5 cm distal of the GEJ) were preferably treated with gastrectomy in 90% of respondents, esophagectomy in 6% and extended gastrectomy in 4%. For choosing optimal treatment for GEJ tumors, adequate determination of tumor location is pivotal because the location affects the surgical procedure. Esophagogastroscopy was deemed most important by 81% of respondents, followed by CTscan in 14%, EUS in 2%, PETscan in 1%, and diagnostic laparoscopy in 1%. Also, the classification that is used affects surgical treatment. A combination of the Siewert classification and the TNM7 classification was preferred by 45% of respondents, whereas 39% used the Siewert classification only and 16% solely favored the TNM7 classification.
Chapter 11 In the prospective UMC Utrecht database of 266 consecutive patients with surgically resectable GEJ adenocarcinomas the diagnostic staging was analyzed. The accuracy of EUS and CT regarding tumor localization according to Siewert, nodal status and its consequences on treatment strategy were assessed. Overall accuracy in determining tumor localization was 73% for EUS and 61% for CT (p=0.018). For EUS, the accuracy decreased when patients were treated with neoadjuvant therapy (82% to 70%, p=0.023), with CT no difference was found (62% to 61%, p=0.884). Accuracy for determining a positive nodal station in patients without neoadjuvant therapy was 77% for EUS and 71% for CT (p=0.001). Accuracy for detecting upper mediastinal lymph nodes was 80–92%, compared to 50–80% for peritumoral and abdominal nodes in both EUS and CT. A radical resection was performed in 88% of patients. Despite the suboptimal accuracy of determining tumor localization with EUS and CT, in only a small number of patients (3%) an intraoperative change of surgical treatment was needed. EUS is superior to CT in determining nodal status and tumor localization in GEJ tumors.
Chapter 12 In the prospective UMC Utrecht database of 266 consecutive patients with surgically resectable GEJ adenocarcinomas the surgical treatment was analyzed. Post-operative histopathological analysis revealed that 25% of patients had a type I tumor, 66% a type II tumor, 6% a type III tumor. I n total, 86% were treated with esophagectomy and 14% with gastrectomy. In patients with a type II GEJ adenocarcinoma, a positive circumferential resection margin was more common with gastrectomy than esophagectomy (29 vs. 11 %; p = 0.025). However, the type of operation did not significantly influence overall survival on multivariate analysis (p = 0.606). Upper mediastinal nodal involvement was present in 11% of patients with a type II tumor
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
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