The structure and function of complex networks

Inspired by empirical studies of networked systems such as the Internet, social networks, and biological networks, researchers have in recent years developed a variety of techniques and models to help us understand or predict the behavior of these systems. Here we review developments in this field, including such concepts as the small-world effect, degree distributions, clustering, network correlations, random graph models, models of network growth and preferential attachment, and dynamical processes taking place on networks.Comment: Review article, 58 pages, 16 figures, 3 tables, 429 references, published in SIAM Review (2003

Body donation for research and teaching purposes: the contribution of blood donation units in the progress of anatomical science

Background: Cadaver’s dissection has a fundamental role in teaching and understanding the anatomy. Postmortem body donation (PMBD) is an important source of cadavers and provides an opportunity to carry out research or educational activities in medicine and surgery. The objective of the current study is to determine the perspectives and attitudes toward PMBD among blood donors (BLD) and elderly people. These data are fundamental to highlight the PMBD extent and individual factors that might influence PMBD. Materials and methods: Six hundred and fifty questionnaires were distributed to 500 (327 male and 173 female, mean age 39.9 ± 9.6 years) blood donors (BLD) and 150 elderly people (62 males and 88 females, mean age 74 ± 9.4 years). A specially designed self-administered questionnaire covering demographic data, knowledge and attitude of the participants concerning body donation (BD) was used. Results: Concerning the perception of BD among BLD and elderly people, the most common reason for BD in both study groups was the contribution in research, while the commonest reason for hesitating about BD was the lack of information, following by personal reasons. The BLD were more likely to be interested in BD for contribution in research and personal reasons. Additionally, BLD were less likely than the elderly to hesitate about BD for religious and personal reasons and more likely to hesitate about BD for not being informed. BLD who were interested in BD for contribution in research were significantly older. Elderly people who hesitated about BD for personal reasons were significantly older. In the BLD group, those who responded that blood and body donation are the same were significantly younger, while in the elderly group — significantly older. The proportion of BLD who declared that blood and body donation is the same was significantly higher in more educated people. Conclusions: A need for well-organised and informative BD programmes is evident. Orientating the public towards this practice is of high moral and medical value, since with this important promotion the altruistic act of BD will expand globally.

Random graphs with arbitrary degree distributions and their applications

Recent work on the structure of social networks and the internet has focussed attention on graphs with distributions of vertex degree that are significantly different from the Poisson degree distributions that have been widely studied in the past. In this paper we develop in detail the theory of random graphs with arbitrary degree distributions. In addition to simple undirected, unipartite graphs, we examine the properties of directed and bipartite graphs. Among other results, we derive exact expressions for the position of the phase transition at which a giant component first forms, the mean component size, the size of the giant component if there is one, the mean number of vertices a certain distance away from a randomly chosen vertex, and the average vertex-vertex distance within a graph. We apply our theory to some real-world graphs, including the world-wide web and collaboration graphs of scientists and Fortune 1000 company directors. We demonstrate that in some cases random graphs with appropriate distributions of vertex degree predict with surprising accuracy the behavior of the real world, while in others there is a measurable discrepancy between theory and reality, perhaps indicating the presence of additional social structure in the network that is not captured by the random graph.Comment: 19 pages, 11 figures, some new material added in this version along with minor updates and correction

Factors affecting medical students in formulating their specialty preferences in Jordan

<p>Abstract</p> <p>Background</p> <p>In recent years there has been a growing appreciation of the issues of career preference in medicine as it may affect student learning and academic performance. However, no such studies have been undertaken in medical schools in Jordan. Therefore, we carried out this study to investigate the career preferences of medical students at Jordan University of Science and Technology and determine factors that might influence their career decisions.</p> <p>Methods</p> <p>A cross-sectional questionnaire-based survey was carried out among second, fourth and sixth year medical students at the Jordan University of Science and Technology, Irbid, Jordan during the academic year 2006/2007. A total of 440 students answered the questionnaire which covered demographic characteristics, specialty preferences, and the factors that influenced these career preferences. Possible influences were selected on the basis of a literature review and discussions with groups of medical students and physicians. Students were asked to consider 14 specialty options and select the most preferred career preference.</p> <p>Results</p> <p>The most preferred specialty expressed by male students was surgery, followed by internal medicine and orthopaedics, while the specialty most preferred by female students was obstetrics and gynaecology, followed by pediatrics and surgery. Students showed little interest in orthopedics, ophthalmology, and dermatology. While 3.1% of females expressed interest in anesthesiology, no male students did. Other specialties were less attractive to most students.</p> <p>Intellectual content of the specialty and the individual's competencies were the most influential on their preference of specialty. Other influential factors were the "reputation of the specialty", "anticipated income", and "focus on urgent care".</p> <p>Conclusion</p> <p>Surgery, internal medicine, pediatrics, and obstetrics and gynaecology were the most preferred specialty preferences of medical students at Jordan University of Science and Technology.</p

At the coalface and the cutting edge: general practitioners’ accounts of the rewards of engaging with HIV medicine

The interviews we conducted with GPs suggest that an engagement with HIV medicine enables clinicians to develop strong and long-term relationships with and expertise about the care needs of people living with HIV ‘at the coalface’, while also feeling connected with a broader network of medical practitioners and other professionals concerned with and contributing to the ever-changing world of science: ‘the cutting edge’. The general practice HIV prescriber is being modelled here as the interface between these two worlds, offering a rewarding opportunity for general practitioners to feel intimately connected to both community needs and scientific change

An Empirical Analysis on Board Monitoring Role and Loan Portfolio Quality Measurement in Banks

This paper aims to analyze the effectiveness of the board monitoring role on specific loan portfolio quality measures in banks (default rate, recovery rate and provisioning rate). We use a sample comprises a totality of Italian-based banks, listed at Borsa Italiana SpA in 2006-2008 and a number of accounting proxies to express the loan portfolio quality of a bank. The results of the analysis show an overall weakness of the board role (expressed by Independents and Audit Committee on board) in monitoring loan portfolio quality of the bank, with the subsequent damage of the interests of stakeholders. A positive contribution of board monitoring, even if partial, is highlighted in two cases: Independents seems improve recovery rate, while the Audit committee enhances provisioning rate in banks. With reference to default rate, a total negative effect of board monitoring is reported. On the base of these results, some managerial implications are proposed