Fractional Dynamics of Network Growth Constrained by aging Node Interactions

In many social complex systems, in which agents are linked by non-linear interactions, the history of events strongly influences the whole network dynamics. However, a class of "commonly accepted beliefs" seems rarely studied. In this paper, we examine how the growth process of a (social) network is influenced by past circumstances. In order to tackle this cause, we simply modify the well known preferential attachment mechanism by imposing a time dependent kernel function in the network evolution equation. This approach leads to a fractional order Barabasi-Albert (BA) differential equation, generalizing the BA model. Our results show that, with passing time, an aging process is observed for the network dynamics. The aging process leads to a decay for the node degree values, thereby creating an opposing process to the preferential attachment mechanism. On one hand, based on the preferential attachment mechanism, nodes with a high degree are more likely to absorb links; but, on the other hand, a node's age has a reduced chance for new connections. This competitive scenario allows an increased chance for younger members to become a hub. Simulations of such a network growth with aging constraint confirm the results found from solving the fractional BA equation. We also report, as an exemplary application, an investigation of the collaboration network between Hollywood movie actors. It is undubiously shown that a decay in the dynamics of their collaboration rate is found, - even including a sex difference. Such findings suggest a widely universal application of the so generalized BA model.Comment: 13 pages; 5 figures; 71 references; as prepared for submission to PLOS ON

A non-dimensional study on both analytic and numeric thermo-elastic behavior of ‎functionally graded thick-walled cylinders under a combination of thermo-‎mechanical loads

Using non-dimensional parameters, the governing equations of the homogeneous and heterogeneous cylinders made of functionally graded material (FGM) were derived under a combination of thermo-mechanical loads. The equations were solved analytically and numerically in a severe temperature and pressure gradient environment. The radial and circumferential stresses together with the radial displacement of FGM cylinder were analytically evaluated and the obtained results of heterogeneous FGM cylinder were compared with conventional homogeneous one. Moreover, in order to assess the accuracy of the derived equations, a numerical solution (NS) was performed using finite element method which was in accordance with the analytical solution (AS). The results of present work show that the use of FGM can optimize the cylinders which are exposed to the joint mechanical and thermal loads

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

External and internal radiation therapy: Past and future directions

Cancer is a leading cause of morbidity and mortality in the modern world. Treatment modalities comprise radiation therapy, surgery, chemotherapy and hormonal therapy. Radiation therapy can be performed by using external or internal radiation therapy. However, each method has its unique properties which undertakes special role in cancer treatment, this question is brought up that: For cancer treatment, whether external radiation therapy is more efficient or internal radiation therapy one? To answer this question, we need to consider principles and structure of individual methods. In this review, principles and application of each method are considered and finally these two methods are compared with each other

Fractional Dynamics of Network Growth Constrained by Aging Node Interactions

In many social complex systems, in which agents are linked by non-linear interactions, the history of events strongly influences the whole network dynamics. However, a class of “commonly accepted beliefs” seems rarely studied. In this paper, we examine how the growth process of a (social) network is influenced by past circumstances. In order to tackle this cause, we simply modify the well known preferential attachment mechanism by imposing a time dependent kernel function in the network evolution equation. This approach leads to a fractional order Barabási-Albert (BA) differential equation, generalizing the BA model. Our results show that, with passing time, an aging process is observed for the network dynamics. The aging process leads to a decay for the node degree values, thereby creating an opposing process to the preferential attachment mechanism. On one hand, based on the preferential attachment mechanism, nodes with a high degree are more likely to absorb links; but, on the other hand, a node’s age has a reduced chance for new connections. This competitive scenario allows an increased chance for younger members to become a hub. Simulations of such a network growth with aging constraint confirm the results found from solving the fractional BA equation. We also report, as an exemplary application, an investigation of the collaboration network between Hollywood movie actors. It is undubiously shown that a decay in the dynamics of their collaboration rate is found, even including a sex difference. Such findings suggest a widely universal application of the so generalized BA model

Schematic diagram representing the dynamical growth of nodes in a network, developing under a preferential attachment mechanism, but also considering limitations imposed by an aging process and screening effects on the growth process (a-c); comparisons with standard preferential attachment are found in (e-f).

<p>Red to blue color shades of nodes represent the attractiveness for new links. The highest attractiveness corresponds to the red color. The radial distance from the central node indicates the arrival time for a node. Old members, because of their age, have a lower chance of being selected. In (e-f), i.e. in the absence of these effects, hubs dominate the attachment process of new links.</p

Panel (a) shows the probability distribution function for different orders of the fractional derivative.

<p>While for <i>α</i> = 1, i.e. the BA model, the expected power law behavior is found, for fractional orders less than unity, there is noticeable deviation from a power law. This could be caused by two competitive processes, namely a preferential attachment mechanism and a screening effect. Panel (b) is the network closeness centrality measure averaged over all nodes; the horizontal axis is the label of nodes according to their arrival time. The comparison for three exponents <i>α</i> point to different behaviors. For high values of <i>α</i>, this measure has high amounts. Elder nodes have short paths to others. The black solid line shows the fitted curve for <i>α</i> = 1. Panel (c) indicates the network clustering coefficient averaged over all nodes for three <i>α</i> exponents. The horizontal axis also gives the label of nodes according to their arrival time. Older nodes have more communities around themselves. Panels (d-f) show the degree-degree correlation averaged over all nodes for the three <i>α</i> exponents. The tendency to bind with similar members is shown to have been increased by including the effects of past events. The inclination toward linking to previously powerful nodes is reduced. This results from the competition between new generations.</p

Comparison between the numerical solution of Eq (5) (solid lines) for exponents close to unity and the solution of the standard BA model (dashed line).

<p>For long times, the solution of the fractional order equation of network growth dynamics for <i>α</i> = 1 tends to the standard BA model.</p

Comparison between Alpha and Calendula for Healing of Third-Degree Burn in Rats: Burn healing in rat by Alpha and Calendula

In this study, we compared the effects of Calendula and Alpha ointment in the treatment of burn wounds and also compared its results with silver sulfadiazine (SSD). Seventy-five male Sprague-Dawley rats were divided into five groups, and similar burn ulcers were produced on anterior surface of thigh of rats. In the first group of rats no treatment was applied, base gel was applied topically to group II, in groups III-V, Alpha, SSD, and Calendula preparations were applied, respectively. Wound healing, contraction, and histopathological evaluation were evaluated at the end of 7, 14, and 21 days. Alpha ointment was equally effective as Calendula gel, and had better efficacy compared to SSD for all markers of wound healing at days of 7, 14, and 21.Alpha and Calendula preparations are less expensive drugs and significantly improve the quality of wound healing and scar formation and are more appropriate treatment choices than SSD. Therefore, we recommended them as alternative to SSD, especially in patients with low economical backgrounds or in those who show adverse reactions to SSD