371 research outputs found

    A New Physical Picture of Pairing Mechanism in Superconductors: Could the Electron be a Composite Particle?

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    The physical pictures of the electron pairing structure and pairing mechanisms in superconductors are reviewed. An initial idea for a new physical picture of the origin and nature of the pairing is proposed. The idea is based on the assumption that the electron is no longer a single fundamental but a composite particle. This property is hidden in the normal state. How a natural pairing could occur in the superconducting state and the processes closely related to this change inside the atom are developed in a new physical picture with new insight(although it needs verification and real evidence for now). An attempt, to show that a zero resistance to a direct current and Josephson effects could be used as example evidences for this assumption, is presented by means of this new insight in general schematical analogy. A possible new research direction, hopefully to achieve room temperature superconductors, is suggested as a consequence.Comment: 17 pages, 12 figures, 46 Reference

    Compact superconducting dual-log spiral resonator with high Q-factor and low power dependence

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    A new dual-log spiral geometry is proposed for microstrip resonators, offering substantial advantages in performance and size reduction at subgigahertz frequencies when realized in superconducting materials. The spiral is logarithmic in line spacing and width such that the width of the spiral line increases smoothly with the increase of the current density, reaching its maximum where the current density is maximum (in its center for 2 resonators). Preliminary results of such a logarithmic ten-turn (2 5 turns) spiral, realized with double-sided YBCO thin film, showed a -factor seven times higher than that of a single ten-turn uniform spiral made of YBCO thin film and 64 times higher than a copper counterpart. The insertion loss of the YBCO dual log-spiral has a high degree of independence of the input power in comparison with a uniform Archimedian spiral, increasing by only 2.5% for a 30-dBm increase of the input power, compared with nearly 31% for the uniform spiral. A simple approximate method, developed for prediction of the resonant frequency of the new resonators, shows a good agreement with the test results

    The Unseen Face of E-Business Project Development

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    The purpose of this paper is intent on identify and analyze the unseen factors of successful or failure of e-business project development. The IT managers must take into account both all costs involved in e-business development and all phases (analysis, design, testing, implementation, maintenance and operation) according to principle of project management for software/systems life cycle development. There are many solutions to exceed these factors of failure among could be counted outsourcing, a good project management, involvement of senior management, a real cost estimation etc.Zadanie pt. „Digitalizacja i udostępnienie w Cyfrowym Repozytorium Uniwersytetu Łódzkiego kolekcji czasopism naukowych wydawanych przez Uniwersytet Łódzki” nr 885/P-DUN/2014 zostało dofinansowane ze środków MNiSW w ramach działalności upowszechniającej nauk

    A geometric morphometric study on geographical Iranian populations of the pod borer, Helicoverpa armigera (Lepidoptera: Noctuidae)

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    Multivariate analyses of the morphological variation in five geographical populations of the pod borer, Helicoverpa armigera (Hübner), was performed using 15 and 12 landmarks selected from the fore- and hindwings respectively. Using their geometric morphometric characters (26 in the forewings and 20 in the hindwings), 287 and 277 images of fore- and hindwings were made respectively. Analyses of size showed the wings of the females are bigger than those of the males (forewing: F = 3.98, P = 0.047; hindwing: F = 14.62, P = 0.000) on populations tested. The discriminant function analysis (DFA) of fore- and hindwings differentiated five geographical populations with 86.1% and 69.3%, respectively. The multivariate analysis of variance (MANOVA) of shape variables in fore- and hindwings indicated significant differences among populations as well as sexes (at least for one of the shape variables). Sex interaction within the populations was significant in fore- and hindwings, particularly based on the hindwing landmarks. The relative warp analysis (RWA) showed well-supported discrimination between sexes. The results showed significant difference between the sexes and also within the populations

    Correction to: Isolated Human and Livestock Echinococcus granulosus Genotypes Using Real-Time PCR of cox1 Gene in Northeast Iran (Acta Parasitologica, (2019), 64, 3, (679-685), 10.2478/s11686-019-00117-w)

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    Unfortunately, the affiliation of Majid Fasihi-Harandi needs to be edited. The correct affiliation is Research Center for Hydatid Disease in Iran, School of Medicine, Kerman University of Medical Sciences, Kerman, Iran

    Risk assessment for the spread of Serratia marcescens within dental-unit waterline systems using Vermamoeba vermiformis

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    Vermamoeba vermiformis is associated with the biofilm ecology of dental-unit waterlines (DUWLs). This study investigated whether V. vermiformis is able to act as a vector for potentially pathogenic bacteria and so aid their dispersal within DUWL systems. Clinical dental water was initially examined for Legionella species by inoculating it onto Legionella selective-medium plates. The molecular identity/profile of the glassy colonies obtained indicated none of these isolates were Legionella species. During this work bacterial colonies were identified as a non-pigmented Serratia marcescens. As the water was from a clinical DUWL which had been treated with Alpron™ this prompted the question as to whether S. marcescens had developed resistance to the biocide. Exposure to Alpron™ indicated that this dental biocide was effective, under laboratory conditions, against S. marcescens at up to 1x108 colony forming units/millilitre (cfu/ml). V. vermiformis was cultured for eight weeks on cells of S. marcescens and Escherichia coli. Subsequent electron microscopy showed that V. vermiformis grew equally well on S. marcescens and E. coli (p = 0.0001). Failure to detect the presence of S. marcescens within the encysted amoebae suggests that V. vermiformis is unlikely to act as a vector supporting the growth of this newly isolated, nosocomial bacterium

    Optimization of flow shop scheduling through a hybrid genetic algorithm for manufacturing companies

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    A task scheduling problem is a process of assigning tasks to a limited set of resources available in a time interval, where certain criteria are optimized. In this way, the sequencing of tasks is directly associated with the executability and optimality of a preset plan and can be found in a wide range of applications, such as: programming flight dispatch at airports, programming production lines in a factory, programming of surgeries in a hospital, repair of equipment or machinery in a workshop, among others. The objective of this study is to analyze the effect of the inclusion of several restrictions that negatively influence the production programming in a real manufacturing environment. For this purpose, an efficient Genetic Algorithm combined with a Local Search of Variable Neighborhood for problems of n tasks and m machines is introduced, minimizing the time of total completion of the tasks. The computational experiments carried out on a set of problem instances with different sizes of complexity show that the proposed hybrid metaheuristics achieves high quality solutions compared to the reported optimal cases

    Length versus radius relationship for ZnO nanowires grown via vapour phase transport

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    We model the growth of ZnO nanowires via vapour phase transport and examine the relationship predicted between the nanowire length and radius. The model predicts that the lengths of the nanowires increase with decreasing nanowire radii. This prediction is in very good agreement with experimental data from a variety of nanowire samples, including samples showing a broad range of nanowire radii and samples grown using a lithographic technique to constrain the nanowire radius. The close agreement of the model and the experimental data strongly support supporting the inclusion of a surface diffusion term in the model for the incorporation of species into a growing nanowire
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