18,588,755 research outputs found

    Introduction to Quantum-Gravity Phenomenology

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    After a brief review of the first phase of development of Quantum-Gravity Phenomenology, I argue that this research line is now ready to enter a more advanced phase: while at first it was legitimate to resort to heuristic order-of-magnitude estimates, which were sufficient to establish that sensitivity to Planck-scale effects can be achieved, we should now rely on detailed analyses of some reference test theories. I illustrate this point in the specific example of studies of Planck-scale modifications of the energy/momentum dispersion relation, for which I consider two test theories. Both the photon-stability analyses and the Crab-nebula synchrotron-radiation analyses, which had raised high hopes of ``beyond-Plankian'' experimental bounds, turn out to be rather ineffective in constraining the two test theories. Examples of analyses which can provide constraints of rather wide applicability are the so-called ``time-of-flight analyses'', in the context of observations of gamma-ray bursts, and the analyses of the cosmic-ray spectrum near the GZK scale.Comment: 46 pages, LaTex. Based on lectures given at the 40th Karpacz Winter School in Theoretical Physic

    Numerical entropy and phason elastic constants of plane random tilings with any 2D-fold symmetry

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    We perform Transition matrix Monte Carlo simulations to evaluate the entropy of rhombus tilings with fixed polygonal boundaries and 2D-fold rotational symmetry. We estimate the large-size limit of this entropy for D=4 to 10. We confirm analytic predictions of N. Destainville et al., J. Stat. Phys. 120, 799 (2005) and M. Widom et al., J. Stat. Phys. 120, 837 (2005), in particular that the large size and large D limits commute, and that entropy becomes insensible to size, phason strain and boundary conditions at large D. We are able to infer finite D and finite size scalings of entropy. We also show that phason elastic constants can be estimated for any D by measuring the relevant perpendicular space fluctuations.Comment: Accepted for publication in Eur. Phys. J.

    Time domain deBroglie wave interferometry along a magnetic guide

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    Time domain deBroglie wave interferometry [Cahn et al, Phys. Rev. Lett. 79, 784] is applied to Rb87 atoms in a magnetic guide. A standing wave light field is carefully aligned along the guiding direction of the magnetic trapping potential from a soft-ferromagnetic 4-foil structure. A sequence of two standing wave pulses is applied to the magnetically trapped atoms. The backscattered light at the atomic density grating revival time is collected and detected via a heterodyning technique. In addition to the observed recoil oscillations that fit the interferometer theory for atoms in free space, we observe a decay of the interferometer contrast on a millisecond time scale with unexpected millisecond-scale oscillations. We find that the oscillating decay is explained by a residual variation of the linear trapping potential along the standing wave direction.Comment: 22 pages, 7 figure

    Examining variation in the expression of tense/aspect to classify the Kikongo Language Cluster

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    In this article we examine variation in the expression of tense and aspect (TA) in 23 modern and two historical Bantu language varieties belonging to Guthrie’s B40, H10 and H30 groups in order to shed light on the internal classification of the Kikongo Language Cluster (KLC). We apply the Comparative Method to this specific set of morphological data to test a recent phylogenetic classification of the KLC. We identify eight widespread TA markers as shared retentions dating back to the period before the internal fragmentation of the KLC. Six of these are inherited from Proto‑Bantu. Two other markers go back to Proto‑Kikongoid and Proto‑Kikongo. They confirm that the KLC constitutes a discrete clade within West‑Coastal Bantu. We furthermore distinguish fourteen shared innovations that took place after the break‑up of the last common ancestor of the KLC. These innovations provide corroborating evidence for three phylogenetic subgroups within the KLC, namely East, South and West, and for the fact that the latter subgroup falls apart in two discrete genealogical subunits. They furthermore testify to the horizontal transmission of TA features between subgroups. Such language convergence often correlates with relatively recent historical developments within the Lower Congo region and contributed to the multilayered constitution of the KLC

    The Main Sources for Technology Management Research: A Bibliometric Approach

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    In this study, it is aimed to determine the main sources of Technology Management (TM) field. Since there are many bibliographic databases, it is important to identify which journal is the most important in T.M., and there are many journals published in this field, it is possible to decide which one is the most important journal for TM, For this purpose, a series of analyzes were performed on bibliographic data of the publications indexed in Web of Science using bibliometrics. The main purpose of the study is to identify and rank the most important journals in the field of TM. In this way, it will be possible to determine the most important publications in the field of TM. To determine the main journal list for the TM area, Bradford law will be used, and citation analysis methods will be used to determine the impact of journals in the field

    A problem based / experiential learning approach to teaching maintenance engineering

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    Good maintenance practice lies at the heart of a manufacturing industry being able to retain its production capabilities and to ensure the integrity of increasingly complex systems. Consequences of system failure can exceed mere monetary penalties to include the well being of staff. From an engineering education perspective, rapid development in technology in parallel with the evolution of traditional engineering disciplines, necessitates the utilization of innovative ways to teach non-traditional or interdisciplinary topics like maintenance. Another challenge in this context, is the ability to allocate time and physical resources in ever more condensed engineering curricula whilst making the learning process engaging for students. This paper details a recent trial to teach a short undergraduate course on maintenance within a mechanical engineering degree where students also look at some safety considerations associated with maintenance practice. A combined Problem Based Learning/Experiential Learning approach applied to machine tool maintenance was adopted using resources readily available in most engineering schools

    Smart hospital emergency system via mobile-based requesting services

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    In recent years, the UK’s emergency call and response has shown elements of great strain as of today. The strain on emergency call systems estimated by a 9 million calls (including both landline and mobile) made in 2014 alone. Coupled with an increasing population and cuts in government funding, this has resulted in lower percentages of emergency response vehicles at hand and longer response times. In this paper, we highlight the main challenges of emergency services and overview of previous solutions. In addition, we propose a new system call Smart Hospital Emergency System (SHES). The main aim of SHES is to save lives through improving communications between patient and emergency services. Utilising the latest of technologies and algorithms within SHES is aiming to increase emergency communication throughput, while reducing emergency call systems issues and making the process of emergency response more efficient. Utilising health data held within a personal smartphone, and internal tracked data (GPU, Accelerometer, Gyroscope etc.), SHES aims to process the mentioned data efficiently, and securely, through automatic communications with emergency services, ultimately reducing communication bottlenecks. Live video-streaming through real-time video communication protocols is also a focus of SHES to improve initial communications between emergency services and patients. A prototype of this system has been developed. The system has been evaluated by a preliminary usability, reliability, and communication performance study

    Optimization of the air gap spacing in a solar water heater with double glass cover

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    A parametric study has been conducted in a solar water heater with double glass cover, in order to minimize heat losses. The air gap spacing between the absorber and the inner glass cover (L1) and between the two glass covers (L2) for the system with 0.7 m x 1.35 m absorber area were varied within the range of 15-50 mm to investigate which combination of gap sizes (L1, L2) would result in minimum total heat losses i.e. including radiation and convection losses. Three-dimensional CFD models have been developed using ANSYS 13.0-FLUENT software. The continuity, momentum and energy equations have been solved, in steady state condition, using pressure-based type solver. A realizable k-є turbulent model has been used, and surface to surface radiation was included. The results showed that as the size of the air gap increases, the velocity of the air in the gap increases which increased the convection part however the total heat losses decreased. The optimum combinations for the present case have been found to be 40, 25 mm, since the overall heat loss was found to be the lowest (216.4 W)

    Nanocharacterization in Dentistry

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    About 80% of US adults have some form of dental disease. There are a variety of new dental products available, ranging from implants to oral hygiene products that rely on nanoscale properties. Here, the application of AFM (Atomic Force Microscopy) and optical interferometry to a range of dentistry issues, including characterization of dental enamel, oral bacteria, biofilms and the role of surface proteins in biochemical and nanomechanical properties of bacterial adhesins, is reviewed. We also include studies of new products blocking dentine tubules to alleviate hypersensitivity; antimicrobial effects of mouthwash and characterizing nanoparticle coated dental implants. An outlook on future “nanodentistry” developments such as saliva exosomes based diagnostics, designing biocompatible, antimicrobial dental implants and personalized dental healthcare is presented

    The CIO role expectations instrument: validation and model testing

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    The validation of IS instruments has not been given the attention that it deserves. This study uses component-based structural equation modelling (PLS/SEM) to investigate the psychometric properties and possible modelling of the CIO role expectations instrument based on data obtained from 174 Australian CIOs. Results show that the CIO role expectation instrument has exhibited solid validity and reliability indices despite some minor weaknesses. The results also demonstrate the possibility to model the constructs of this instrument in different null and hierarchical models, and the validity of this instrument to measure the CIO role in different types of industries not just the healthcare sector in which it was developed. The results provide support for CIO role theory on two central issues: (1) CIOs are fulfilling a configuration of roles not just one specific role (2) the CIO roles can be grouped into two major categories: supply side roles and demand side roles
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