Experience versus Talent Shapes the Structure of the Web

We use sequential large-scale crawl data to empirically investigate and validate the dynamics that underlie the evolution of the structure of the web. We find that the overall structure of the web is defined by an intricate interplay between experience or entitlement of the pages (as measured by the number of inbound hyperlinks a page already has), inherent talent or fitness of the pages (as measured by the likelihood that someone visiting the page would give a hyperlink to it), and the continual high rates of birth and death of pages on the web. We find that the web is conservative in judging talent and the overall fitness distribution is exponential, showing low variability. The small variance in talent, however, is enough to lead to experience distributions with high variance: The preferential attachment mechanism amplifies these small biases and leads to heavy-tailed power-law (PL) inbound degree distributions over all pages, as well as over pages that are of the same age. The balancing act between experience and talent on the web allows newly introduced pages with novel and interesting content to grow quickly and surpass older pages. In this regard, it is much like what we observe in high-mobility and meritocratic societies: People with entitlement continue to have access to the best resources, but there is just enough screening for fitness that allows for talented winners to emerge and join the ranks of the leaders. Finally, we show that the fitness estimates have potential practical applications in ranking query results

Preferential survival in models of complex ad hoc networks

There has been a rich interplay in recent years between (i) empirical investigations of real world dynamic networks, (ii) analytical modeling of the microscopic mechanisms that drive the emergence of such networks, and (iii) harnessing of these mechanisms to either manipulate existing networks, or engineer new networks for specific tasks. We continue in this vein, and study the deletion phenomenon in the web by following two different sets of web-sites (each comprising more than 150,000 pages) over a one-year period. Empirical data show that there is a significant deletion component in the underlying web networks, but the deletion process is not uniform. This motivates us to introduce a new mechanism of preferential survival (PS), where nodes are removed according to a degree-dependent deletion kernel. We use the mean-field rate equation approach to study a general dynamic model driven by Preferential Attachment (PA), Double PA (DPA), and a tunable PS, where c nodes (c<1) are deleted per node added to the network, and verify our predictions via large-scale simulations. One of our results shows that, unlike in the case of uniform deletion, the PS kernel when coupled with the standard PA mechanism, can lead to heavy-tailed power law networks even in the presence of extreme turnover in the network. Moreover, a weak DPA mechanism, coupled with PS, can help make the network even more heavy-tailed, especially in the limit when deletion and insertion rates are almost equal, and the overall network growth is minimal. The dynamics reported in this work can be used to design and engineer stable ad hoc networks and explain the stability of the power law exponents observed in real-world networks.Comment: 9 pages, 6 figure

Let Your CyberAlter Ego Share Information and Manage Spam

Almost all of us have multiple cyberspace identities, and these {\em cyber}alter egos are networked together to form a vast cyberspace social network. This network is distinct from the world-wide-web (WWW), which is being queried and mined to the tune of billions of dollars everyday, and until recently, has gone largely unexplored. Empirically, the cyberspace social networks have been found to possess many of the same complex features that characterize its real counterparts, including scale-free degree distributions, low diameter, and extensive connectivity. We show that these topological features make the latent networks particularly suitable for explorations and management via local-only messaging protocols. {\em Cyber}alter egos can communicate via their direct links (i.e., using only their own address books) and set up a highly decentralized and scalable message passing network that can allow large-scale sharing of information and data. As one particular example of such collaborative systems, we provide a design of a spam filtering system, and our large-scale simulations show that the system achieves a spam detection rate close to 100%, while the false positive rate is kept around zero. This system has several advantages over other recent proposals (i) It uses an already existing network, created by the same social dynamics that govern our daily lives, and no dedicated peer-to-peer (P2P) systems or centralized server-based systems need be constructed; (ii) It utilizes a percolation search algorithm that makes the query-generated traffic scalable; (iii) The network has a built in trust system (just as in social networks) that can be used to thwart malicious attacks; iv) It can be implemented right now as a plugin to popular email programs, such as MS Outlook, Eudora, and Sendmail.Comment: 13 pages, 10 figure

Nano-structural, Electrical and Mechanical Characterization of Zirconium Oxide Thin Films as a Function of Annealing Temperature and Time

Zr thin films were deposited by DC magnetron sputtering technique on Si substrate and then post-annealed at different temperatures (150-750 °C in steps of 150 °C) and times (60 and 180 min) with flow of oxygen. X-ray diffraction (XRD) method was used for study of crystallographic structure. These results showed an orthorhombic structure for annealed films at 150 and a mixed structure of monoclinic and tetragonal for annealed films at higher temperatures (300-750 ºC). XRD result also showed that an increase in annealing temperature and time caused increasing of crystalline size. EDAX and AFM tech-niques were employed for investigation of chemical composition and surface morphology of samples, re-spectively. The results showed a granular structure for all samples, while the O / Zr ratio, grains size and surface roughness were increased with increasing of annealing temperature and time. A two probe instru-ment was used for electrical properties investigation, while hardness of films was measured by nano-indentation test. These results showed that increasing of annealing temperature and time caused increas-ing of electrical resistance and decreasing of hardness in the films. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3513

PP-005 Clarithromycin resistance assessment in Helicobacter pylori isolates by using 23S rRNA gene molecular markers

Background: H. pylori is a relatively fastidious and microaerophilic microorganism and therefore standard phenotypic susceptibility tests, even in the hands of experts, are slow and can take at least 10 14 days. Molecular based diagnostic assays by using molecular markers for resistance detection offer an attractive alternative approach to obtain susceptibilities to antibiotics with greater accuracy and speed, and the possibility of a same day result. The aim of this study is the assessment of clarithromycin resistance by using molecular markers. Methods: This cross-sectional descriptive study was performed on 200 gastric biopsy specimens which were obtained from patients undergoing upper gastrointestinal tract endoscopy in Hajar hospital of Shahrekord, by using TaqMan real-time PCR. Initially, H. pylori strains were identified by RUT and PCR. Then, by this regard that accumulation of mutations associated with resistance to clarithromycin were in the region between nucleotides 2142 2144 of 23S rRNA gene, the first probe was designed to be able the distinguish between sensitive and resistant strains. Finally four probes were designed that each be able to identify only one mutation associated with a particular level of clarithromycin resistance. Results: Out of 200 samples, 164 (82%) were H. pylori positive. Overall, clarithromycin susceptible strains were detected in 105 (64.02%) patients and clarithromycin resistance were detected in 59 (35.98%) which were identified as 4 (2.44%) A2144G, 26 (15.85%) A2143G, 15 (9.15%) A2143C and 20 (12.19%) A2142G point mutations. Purely resistant strains were detected in 38 (23.17%), while heteroresistant were found in the remaining 16 (9.76%) cases. Genotype of 5 (8.47%) strains was not detected. This data was confirmed by PCR-RFLP technique. Conclusion: Results showed that Real-time PCR assay in combination with molecular markers has high accuracy to simultaneously identify H. pylori and clarithromycin resistance types directly in gastric biopsy specimens in short time

Topological phase transition in a network model with preferential attachment and node removal

Preferential attachment is a popular model of growing networks. We consider a generalized model with random node removal, and a combination of preferential and random attachment. Using a high-degree expansion of the master equation, we identify a topological phase transition depending on the rate of node removal and the relative strength of preferential vs. random attachment, where the degree distribution goes from a power law to one with an exponential tail.Comment: The final publication is available at http://www.epj.or

Intelligent evacuation management systems: A review

Crowd and evacuation management have been active areas of research and study in the recent past. Various developments continue to take place in the process of efficient evacuation of crowds in mass gatherings. This article is intended to provide a review of intelligent evacuation management systems covering the aspects of crowd monitoring, crowd disaster prediction, evacuation modelling, and evacuation path guidelines. Soft computing approaches play a vital role in the design and deployment of intelligent evacuation applications pertaining to crowd control management. While the review deals with video and nonvideo based aspects of crowd monitoring and crowd disaster prediction, evacuation techniques are reviewed via the theme of soft computing, along with a brief review on the evacuation navigation path. We believe that this review will assist researchers in developing reliable automated evacuation systems that will help in ensuring the safety of the evacuees especially during emergency evacuation scenarios

An Ontological Approach to Inform HMI Designs for Minimizing Driver Distractions with ADAS

ADAS (Advanced Driver Assistance Systems) are in-vehicle systems designed to enhance driving safety and efficiency as well as comfort for drivers in the driving process. Recent studies have noticed that when Human Machine Interface (HMI) is not designed properly, an ADAS can cause distraction which would affect its usage and even lead to safety issues. Current understanding of these issues is limited to the context-dependent nature of such systems. This paper reports the development of a holistic conceptualisation of how drivers interact with ADAS and how such interaction could lead to potential distraction. This is done taking an ontological approach to contextualise the potential distraction, driving tasks and user interactions centred on the use of ADAS. Example scenarios are also given to demonstrate how the developed ontology can be used to deduce rules for identifying distraction from ADAS and informing future designs