258 research outputs found
How Damage Diversification Can Reduce Systemic Risk
We consider the problem of risk diversification in complex networks. Nodes
represent e.g. financial actors, whereas weighted links represent e.g.
financial obligations (credits/debts). Each node has a risk to fail because of
losses resulting from defaulting neighbors, which may lead to large failure
cascades. Classical risk diversification strategies usually neglect network
effects and therefore suggest that risk can be reduced if possible losses
(i.e., exposures) are split among many neighbors (exposure diversification,
ED). But from a complex networks perspective diversification implies higher
connectivity of the system as a whole which can also lead to increasing failure
risk of a node. To cope with this, we propose a different strategy (damage
diversification, DD), i.e. the diversification of losses that are imposed on
neighboring nodes as opposed to losses incurred by the node itself. Here, we
quantify the potential of DD to reduce systemic risk in comparison to ED. For
this, we develop a branching process approximation that we generalize to
weighted networks with (almost) arbitrary degree and weight distributions. This
allows us to identify systemically relevant nodes in a network even if their
directed weights differ strongly. On the macro level, we provide an analytical
expression for the average cascade size, to quantify systemic risk.
Furthermore, on the meso level we calculate failure probabilities of nodes
conditional on their system relevance
A k-shell decomposition method for weighted networks
We present a generalized method for calculating the k-shell structure of
weighted networks. The method takes into account both the weight and the degree
of a network, in such a way that in the absence of weights we resume the shell
structure obtained by the classic k-shell decomposition. In the presence of
weights, we show that the method is able to partition the network in a more
refined way, without the need of any arbitrary threshold on the weight values.
Furthermore, by simulating spreading processes using the
susceptible-infectious-recovered model in four different weighted real-world
networks, we show that the weighted k-shell decomposition method ranks the
nodes more accurately, by placing nodes with higher spreading potential into
shells closer to the core. In addition, we demonstrate our new method on a real
economic network and show that the core calculated using the weighted k-shell
method is more meaningful from an economic perspective when compared with the
unweighted one.Comment: 17 pages, 6 figure
Worldwide spreading of economic crisis
We model the spreading of a crisis by constructing a global economic network
and applying the Susceptible-Infected-Recovered (SIR) epidemic model with a
variable probability of infection. The probability of infection depends on the
strength of economic relations between the pair of countries, and the strength
of the target country. It is expected that a crisis which originates in a large
country, such as the USA, has the potential to spread globally, like the recent
crisis. Surprisingly we show that also countries with much lower GDP, such as
Belgium, are able to initiate a global crisis. Using the {\it k}-shell
decomposition method to quantify the spreading power (of a node), we obtain a
measure of ``centrality'' as a spreader of each country in the economic
network. We thus rank the different countries according to the shell they
belong to, and find the 12 most central countries. These countries are the most
likely to spread a crisis globally. Of these 12 only six are large economies,
while the other six are medium/small ones, a result that could not have been
otherwise anticipated. Furthermore, we use our model to predict the crisis
spreading potential of countries belonging to different shells according to the
crisis magnitude.Comment: 13 pages, 4 figures and Supplementary Materia
College Students’ Attitudes Towards Remote Instruction During the Coronavirus Pandemic: Future Directions
Undergraduate and graduate education students completed a survey to examine their attitudes toward remote instruction during the coronavirus pandemic. At the conclusion of the Spring 2020 semester in which all courses transitioned from a face-to-face to an online format, students, N = 93, were asked to describe what worked well in their courses in regards to their remote instruction experience and, when things did not go so well, what would have helped to make their experience better. The qualitative data were coded, and inductive analysis was used to generate categories (Johnson, 2012; Strauss & Corbin, 1998). Responses were grouped into labeled categories, and illustrative quotes were chosen to represent categories. Results revealed that remote instruction was somewhat worse than regular instruction. Across all respondents, analysis of responses to the open-ended questions revealed four themes that students believed were integral to remote instruction, (1) communication between students and faculty, (2) flexibility with assignments, (3) increased virtual interaction, and (4) support. Findings suggest how faculty can facilitate and ameliorate remote and hybrid instruction for their students
The Role of Nano-Technology in Sustainable Construction: A Case Study of Using Nano Granite Waste Particles in Cement Mortar
Better understanding of the properties of cement-based materials, one of the most widely used building materials, at the nano-scale is crucial to improve its functionality in the built environment. This paper presents areas of using nano-materials in improving the characteristics of cement-based materials as well as introducing a new role of nano-technology together with waste management in enhancing the concept of sustainable construction. A case study on the use of nano-granite waste particles as a replacement of cement and fine aggregate in mortar production is presented. The research concluded that replacing 5% cement and 10% sand with nano-granite waste in the mortar mix increased the compressive strength of the green mortar by 41% compared to that of the control mix (CM). SEM images reinforced this result as the green mortar mix showed maximum density and minimum micro cracks and number of pores. A comparative study between the green mortar and traditional mortar was carried out using sustainability indicators to examine the environmental, social and economic implications. The environmental and social attributes showed a saving of 10% in the field of resource consumption, whereas savings in energy consumption and CO2 emissions reached 5%. The economic field showed saving of 6.5% indicating promising results in enhancing the sustainable construction industry
Which electronic health record system should we use? A systematic review
The UK government had intended to introduce a comprehensive EHRs system in England by 2020. These EHRs would run across primary, secondary, and social care linking data in a single digital platform. This systematic review's objectives were to identify studies that compare EHRs in terms of direct comparison between systems and evaluate them using System and Software Quality Requirements and Evaluation (SQuaRE) ISO/IEC 25010. A systematic review was performed by searching EMBASE and Ovid MEDLINE databases between 1974 and April 2021. All original studies that appraised EHR systems and their providers were included. The main outcome measures were EHR system comparison and SQuaRE's eight characteristics: functional suitability, performance efficiency, compatibility, usability, reliability, security, maintainability, and portability. A total of 724 studies were identified using the search criteria. After review of titles and abstracts, this was filtered down to 40 studies as per exclusion and inclusion criteria set out in our study selection. Seven studies compared more than one EHR. The following number of studies looked at the various aspects of the SQuaRE respectively. Nineteen studies addressed functional suitability, n=18 performance efficiency, n=12 compatibility, n=25 usability, n=6 reliability, n=2 security, n=16 maintainability, and n=13 portability. Epic was the most studied EHR system and one of the most implemented vendors in the USA market, and one of the top ten in UK. It is difficult to assess which is the most advantageous EHR system currently available when looking at them in accordance with SQuaRE's eight characteristics for software evaluation
The Swiss Board Directors Network in 2009
We study the networks formed by the directors of the most important Swiss
boards and the boards themselves for the year 2009. The networks are obtained
by projection from the original bipartite graph. We highlight a number of
important statistical features of those networks such as degree distribution,
weight distribution, and several centrality measures as well as their
interrelationships. While similar statistics were already known for other board
systems, and are comparable here, we have extended the study with a careful
investigation of director and board centrality, a k-core analysis, and a
simulation of the speed of information propagation and its relationships with
the topological aspects of the network such as clustering and link weight and
betweenness. The overall picture that emerges is one in which the topological
structure of the Swiss board and director networks has evolved in such a way
that special actors and links between actors play a fundamental role in the
flow of information among distant parts of the network. This is shown in
particular by the centrality measures and by the simulation of a simple
epidemic process on the directors network.Comment: Submitted to The European Physical Journal
Effect of airplane transport of donor livers on post-liver transplantation survival
Aim: To evaluate the effect of long haul airplane transport of donor livers on post-transplant outcomes.
Methods: A retrospective cohort study of patients who received a liver transplantation was performed in Perth, Australia from 1992 to 2012. Donor and recipient characteristics information were extracted from Western Australian liver transplantation service database. Patients were followed up for a mean of six years. Patient and graft survival were evaluated and compared between patients who received a local donor liver and those who received an airplane transported donor liver. Predictors of survival were determined by univariate and multivariate analysis using cox regression.
Results: One hundred and ninety-three patients received a local donor liver and 93 patients received an airplane transported donor liver. Airplane transported livers had a significantly lower alanine transaminase (mean: 45 U/L vs 84 U/L, P = 0.035), higher donor risk index (mean: 1.88 vs 1.42, P \u3c 0.001) and longer cold ischemic time (CIT) (mean: 10.1 h vs 6.4 h, P \u3c 0.001). There was a weak correlation between CIT and transport distance (r 2 = 0.29, P \u3c 0.001). Mean follow up was six years and 93 patients had graft failure. Multivariate analysis found only airplane transport retained significance for graft loss (HR = 1.92, 95%CI: 1.16-3.17). One year graft survival was 0.88 for those with a local liver and was 0.71 for those with an airplane transported liver. One year graft loss was due to primary graft non-function or associated with preservation injury in 20.8% of recipients of an airplane transported liver compared with 4.6% in those with a local liver (P = 0.027).
Conclusion: Airplane transport of donor livers was independently associated with reduced graft survival following liver transplantation
The association of fat and other macronutrients with breast cancer: a case-control study from Greece.
The Greek diet is characterized by a high total fat but low saturated fat intake. In a hospital-based case-control study of female breast cancer conducted in Athens (1989-91), 820 patients with confirmed cancer of the breast were compared with 795 orthopaedic patient controls and 753 hospital visitor controls, matched to the cases by age and interviewer. Diet was ascertained through a semiquantitative food frequency questionnaire; macronutrient intakes were estimated from the nutrient content of a selected typical portion size for each specified food item, summed for all items. Logistic regression was used to analyse the data, controlling for demographic and reproductive risk factors for breast cancer as well as for total energy intake and mutual confounding influences among nutrients. There was no significant or suggestive association of total protein, total fat, categories of fat or total carbohydrates with breast cancer risk. Thus, the mutually adjusted relative risk per quintile and (in parenthesis) 95% confidence interval were: for protein, 1.06 (0.94-1.20); saturated fat, 0.99 (0.89-1.11); monounsaturated fat, 0.97 (0.88-1.07), polyunsaturated fat, 1.05 (0.97-1.13); and total carbohydrates, 1.03 (0.94-1.12). In alternative analytical approaches only total protein appeared to be positively associated to the occurrence of breast cancer with some consistency, but the results were far from statistically significant. These findings do not support a role for fat or other energy-generating nutrients in the aetiology of breast cancer
Problems of training international students to pass the final test exam during distance learning in medical universities
Abstract. The article shows problems of training the graduates-citizens of foreign countries to licensing integrated exam «Krok 2. Medicine», such as academic dishonesty of students, particularly, during online classes and remote diagnostic-training testing. Thus, remote diagnostic-training testing requires improvement of the methodology with the involvement of new information and communication technologies. The written diagnostic-training testing allowed to select students of high-risk group of not passing the licensing integrated exam «Krok 2. Medicine» and should be modified as a change in content on each testing
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