25,267 research outputs found

    A Novel Framework for Software Defined Wireless Body Area Network

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    Software Defined Networking (SDN) has gained huge popularity in replacing traditional network by offering flexible and dynamic network management. It has drawn significant attention of the researchers from both academia and industries. Particularly, incorporating SDN in Wireless Body Area Network (WBAN) applications indicates promising benefits in terms of dealing with challenges like traffic management, authentication, energy efficiency etc. while enhancing administrative control. This paper presents a novel framework for Software Defined WBAN (SDWBAN), which brings the concept of SDN technology into WBAN applications. By decoupling the control plane from data plane and having more programmatic control would assist to overcome the current lacking and challenges of WBAN. Therefore, we provide a conceptual framework for SDWBAN with packet flow model and a future direction of research pertaining to SDWBAN.Comment: Presented on 8th International Conference on Intelligent Systems, Modelling and Simulatio

    DNA folding and melting observed in real time redefine the energy landscape

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    We report real-time observations of the folding and melting of DNA by probing two active sites of a hairpin structure, the bases and the stem end, and using an ultrafast T-jump. Studies at different initial temperatures (before, during, and after melting) provide the time scale of water heating (<20 ps), single-strand destacking (700 ps to 2 ns), and hairpin destacking (microseconds and longer) in solutions of various ionic strengths and pH values. The behavior of transient changes gives direct evidence to the existence of intermediate collapsed structures, labile in destacking but compact in nature, and indicates that melting is not a two-state process. We propose a landscape that is defined by these nucleation structures and destacking for efficient folding and melting

    Regularization of Vertical-Cavity Surface-Emitting Lasers emission by periodic non-Hermitian potentials

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    We propose a novel physical mechanism based on periodic non-Hermitian potentials to efficiently control the complex spatial dynamics of broad-area lasers, particularly in Vertical-Cavity Surface-Emitting Lasers (VCSELs), achieving a stable emission of maximum brightness. Radially dephased periodic refractive index and gain-loss modulations accumulate the generated light from the entire active layer and concentrate it around the structure axis to emit narrow, bright beams. The effect is due to asymmetric-inward radial coupling between transverse modes, for particular phase differences of the refractive index and gain-loss modulations. Light is confined into a central beam with large intensity opening the path to design compact, bright and efficient broad-area light sources. We perform a comprehensive analysis to explore the maximum central intensity enhancement and concentration regimes. The study reveals that the optimum schemes are those holding unidirectional inward coupling but not fulfilling a perfect local PT-symmetry.Comment: 4 pages, 4 figure

    Supergravity inflation on a brane

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    We discuss supergravity inflation in braneworld cosmology for the class of potentials V(ϕ)=αϕnexp(βmϕm)V(\phi)=\alpha \phi^n\rm{exp}(-\beta^m \phi^m) with m=1, 2m=1,~2. These minimal SUGRA models evade the η\eta problem due to a broken shift symmetry and can easily accommodate the observational constraints. Models with smaller nn are preferred while models with larger nn are out of the 2σ2\sigma region. Remarkably, the field excursions required for 6060 ee-foldings stay sub-planckian Δϕ<1\Delta\phi <1.Comment: 10 pages, 4 figure

    X-ray Absorption Near Edge Structure of FePt nanoclusters

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    X-ray Absorption Near Edge Structure [XANES] of FePt nanoclusters has been studied using a full multiple scattering, self-consistent field [SCF], real-space Green`s function approach realized via the powerful ab initio FEFF8 code. One purpose of our study is to determine the sensitivity of Pt L3 edge with respect to the size and shape of the FePt nanoclusters. We also give the results of the calculations with respect to the Fe L3 edge. Calculations are made with and without core-hole for two main reasons, to check and cross-check the FEFF code and also since in some cases it is known such as Pt clusters that better results are obtained without the core-hole. This is mainly because the screening electron will occupy empty d or f states and correspondingly reduce the white line intensity.Comment: TeX version 3.14159, LaTex2e, 6 pages with 6 figure

    Near-infrared photoluminescence from molecular crystals containing tellurium

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    We report the observation of near-infrared photoluminescence from Te4(Ga2Cl7)2 and Te4(Al2Cl7)2 molecular crystals containing Te42+ polycations. The experimental and theoretical results clearly revealed that Te42+ polycation is one smart near-infrared emitter with characteristic emission peaks at 1252 and 1258 nm for Te4(Ga2Cl7)2 and Te4(Al2Cl7)2 crystals, respectively, resulting from the intrinsic electronic transitions of Te42+. Furthermore, it was also found that the emissions strongly depend on the excitation wavelengths for both Te4(Ga2Cl7)2 and Te4(Al2Cl7)2 samples, most possibly owing to the co-existence of other Te-related optically active centers. This research not only enriches the species of luminescent charged p-block element polyhedra and deepens the understanding of Te-related photophysical behaviors, but also may stimulate efforts for designing novel material systems using such active centers. It is also greatly expected that these sub-nanometer optically active species could exist in other systems such as glasses, polymers, and bulk optical crystals, and the stabilization of these centers in widely used hosts will pave the way for their practical applications

    Formal Availability Analysis using Theorem Proving

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    Availability analysis is used to assess the possible failures and their restoration process for a given system. This analysis involves the calculation of instantaneous and steady-state availabilities of the individual system components and the usage of this information along with the commonly used availability modeling techniques, such as Availability Block Diagrams (ABD) and Fault Trees (FTs) to determine the system-level availability. Traditionally, availability analyses are conducted using paper-and-pencil methods and simulation tools but they cannot ascertain absolute correctness due to their inaccuracy limitations. As a complementary approach, we propose to use the higher-order-logic theorem prover HOL4 to conduct the availability analysis of safety-critical systems. For this purpose, we present a higher-order-logic formalization of instantaneous and steady-state availability, ABD configurations and generic unavailability FT gates. For illustration purposes, these formalizations are utilized to conduct formal availability analysis of a satellite solar array, which is used as the main source of power for the Dong Fang Hong-3 (DFH-3) satellite.Comment: 16 pages. arXiv admin note: text overlap with arXiv:1505.0264

    The Impact of Exchange Rate Depreciation on Economic and Business Growth in Pakistan

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    Depreciation remained a common factor in Pakistani economic history in different regimes, which affected different economic variables, especially the growth and business sector. We have linked depreciation with economic and business growth for Pakistan in this paper. Using time series data from 1976 to 2010 and employing cointegration followed by the Error Correction Model, we find that exchange rate depreciation has adversely affected growth in the business sector, notably Investment and FDI, while net export has a positive association with the exchange rate. All these findings reveal that depreciation is not a good practice because it has negative impact for growth in the business sector. The present scenario of the flexible exchange rate doesn't allow the corresponding authorities to set desirable exchange rates, however, the government must reinforce the real sector in order to ensure a stable exchange rate and hence macroeconomic stability. Keywords: Foreign Exchange; General; Open Economy Macroeconomics; Economic Growth of Open Economie
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