1,223 research outputs found

    Robust Power and Subcarrier Allocation for OFDM-based Cognitive Radio Networks Considering Spectrum Sensing Uncertainties

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    ‎In this paper‎, ‎we address power and subcarrier allocation for cooperative cognitive radio (CR) networks in the presence of spectrum sensing errors‎. ‎First‎, ‎we derive the mutual interference of primary and secondary networks affecting each other by taking into account spectrum sensing errors‎. ‎Then‎, ‎taking into account the interference constraint imposed by the cognitive network to the primary user and the power budget constraint of cognitive network‎, ‎we maximize the achievable data rates of secondary users‎. ‎Besides‎, ‎in a multi secondary user scenario‎, ‎we propose a suboptimal but low complexity power and subcarrier allocation algorithm to solve the formulated optimization problem‎. ‎Our numerical results indicate that the proposed power loading scheme increases the cognitive achievable data rates compared to classical power loading algorithms that do not consider spectrum sensing errors‎

    On invariant sets in Lagrangian graphs

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    In this exposition, we show that a Hamiltonian is always constant on a compact invariant connected subset which lies in a Lagrangian graph provided that the Hamiltonian and the graph are smooth enough. We also provide some counterexamples for the case that the Hamiltonians are not smooth enough.Comment: 4 page

    Particle dynamics inside shocks in Hamilton-Jacobi equations

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    Characteristics of a Hamilton-Jacobi equation can be seen as action minimizing trajectories of fluid particles. For nonsmooth "viscosity" solutions, which give rise to discontinuous velocity fields, this description is usually pursued only up to the moment when trajectories hit a shock and cease to minimize the Lagrangian action. In this paper we show that for any convex Hamiltonian there exists a uniquely defined canonical global nonsmooth coalescing flow that extends particle trajectories and determines dynamics inside the shocks. We also provide a variational description of the corresponding effective velocity field inside shocks, and discuss relation to the "dissipative anomaly" in the limit of vanishing viscosity.Comment: 15 pages, no figures; to appear in Philos. Trans. R. Soc. series

    The rate of convergence of new Lax-Oleinik type operators for time-periodic positive definite Lagrangian systems

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    Assume that the Aubry set of the time-periodic positive definite Lagrangian LL consists of one hyperbolic 1-periodic orbit. We provide an upper bound estimate of the rate of convergence of the family of new Lax-Oleinik type operators associated with LL introduced by the authors in \cite{W-Y}. In addition, we construct an example where the Aubry set of a time-independent positive definite Lagrangian system consists of one hyperbolic periodic orbit and the rate of convergence of the Lax-Oleinik semigroup cannot be better than O(1t)O(\frac{1}{t})

    4G: A User-Centric System

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    The Founder Effect? -FXIII Deficiency in Southeast Iran: A Molecular Study Report

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    Background: Congenital factor XIII (FXIII) deficiency is an extremely rare bleeding disorder (RBD) with different clinical coagulation disorders and great impacts on the perioperative patient outcome. Its prevalence in Southeast Iran is approximately 4,000 times higher than the worldwide prevalence, with Trp187Arg (c.559T> C as the only causative mutation of FXIIID there. We investigated the founder effect of rs1742924, rs4960181, rs3778360 and rs4142290 using haplotype analysis to define the genetic phenomenon in this geographic region. Materials and Methods: In a case-control study, 10 patients with FXIIID and 10 healthy individuals were assessed. Initially, Trp187Arg (c.559T> C) mutation was assessed in all study populations using a PCR-RFLP technique, then haplotype analysis was performed by assessing rs1742924, rs4960181, rs3778360 and rs4142290 polymorphisms. Data were analyzed using a two-proportion z-test. Results: All patients were homozygote for Trp187Arg (c.559T>C), and this mutation was not observed in any form of homozygote or heterozygote in the control group. Polymorphisms in rs1742924, rs4960181, and rs377836 were homozygote (TT, GG, GG, respectively) and T, G, and G alleles distribution in cases and controls with significant difference (P<0.001, P<0.001, and P=0.01 respectively). Rs4142290 polymorphism showed no significant difference between patients and controls (P=0.3). Two types of haplotypes were observed in the case group, and haplotype number 1* was observed among 90% of them, while not observed in the control group. Conclusion: It seems that founder effectors of haplotype number *1 have more antiquity versus other haplotypes, and probably founder effect is responsible for this high prevalence of FXIIID in the southeast of Iran

    The central region of M83: Massive star formation, kinematics, and the location and origin of the nucleus

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    We report new near-IR integral field spectroscopy of the central starburst region of the barred spiral galaxy M83 obtained with CIRPASS on Gemini-S, which we analyse in conjunction with GHaFaS Fabry-Perot data, an AAT IRIS2 Ks-band image, and near- and mid-IR imaging from the Hubble and Spitzer space telescopes. The bulk of the current star formation activity is hidden from optical view by dust extinction, but is seen in the near- and mid-IR to the north of the nucleus. This region is being fed by inflow of gas through the bar of M83, traced by the prominent dust lane entering into the circumnuclear region from the north. An analysis of stellar ages confirms that the youngest stars are indeed in the northwest. A gradual age gradient, with older stars further to the south, characterises the well-known star-forming arc in the central region of M83. Detailed analyses of the Pa beta ionised gas kinematics and near-IR imaging confirm that the kinematic centre coincides with the photometric centre of M83, and that these are offset significantly, by about 3 arcsec or 60 pc, from the visible nucleus of the galaxy. We discuss two possible options, the first of which postulates that the kinematic and photometric centre traces a galaxy nucleus hidden by a substantial amount of dust extinction, in the range A_V=3-10 mag. By combining this information with kinematic results and using arguments from the literature, we conclude that such a scenario is, however, unlikely, as is the existence of other "hidden" nuclei in M83. We thus concur with recent authors and favour a second option, in which the nucleus of the galaxy is offset from its kinematic and photometric centre. This is presumably a result of some past interaction, possibly related to the event which lies at the origin of the disturbance of the outer disk of the galaxy. (Abridged)Comment: MNRAS, in press; 16 pages latex, 15 figure

    MicroRNA-129-1 acts as tumour suppressor and induces cell cycle arrest of GBM cancer cells through targeting IGF2BP3 and MAPK1

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    Background MicroRNA-129-1 (miR-129-1) seems to behave as a tumour suppressor since its decreased expression is associated with different tumours such as glioblastoma multiforme (GBM). GBM is the most common form of brain tumours originating from glial cells. The impact of miR-129-1 downregulation on GBM pathogenesis has yet to be elucidated. Methods MiR-129-1 was overexpressed in GBM cells, and its effect on proliferation was investigated by cell cycle assay. MiR-129-1 predicted targets (CDK6, IGF1, HDAC2, IGF2BP3 and MAPK1) were also evaluated by western blot and luciferase assay. Results Restoration of miR-129-1 reduced cell proliferation and induced G1 accumulation, significantly. Several functional assays confirmed IGF2BP3, MAPK1 and CDK6 as targets of miR-129-1. Despite the fact that IGF1 expression can be suppressed by miR-129-1, through 30-untranslated region complementary sequence, we could not find any association between IGF1 expression and GBM. MiR-129-1 expression inversely correlates with CDK6, IGF2BP3 and MAPK1 in primary clinical samples. Conclusion This is the first study to propose miR129-1 as a negative regulator of IGF2BP3 and MAPK1 and also a cell cycle arrest inducer in GBM cells. Our data suggests miR-129-1 as a potential tumour suppressor and presents a rationale for the use of miR-129-1 as a novel strategy to improve treatment response in GBM
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