5,472 research outputs found

    Communication Between Process and Structure: Modelling and Simulating Message Reference Networks with COM/TE

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    Focusing on observable message signs and referencing structures, communication processes can be described and analysed as message reference networks which are characterized by dynamic pattern evolution. Computational simulation provides a way of obtaining insights into the factors driving such processes. Our paper describes a theoretical framework for communication-oriented modelling — the COM approach — that is centred around the notion of social visibility as a reputation mechanism. The approach contrasts with agent-based social networks on the one hand, and with bibliometric document networks on the other. In introducing our simulation environment COM/TE, typical properties of message reference networks are discussed in terms of a case study which deals with the impact of different media and styles of communication on emergent patterns of social visibility.Communication, Communication-Oriented Modelling, Message Sign, Dynamic Networks, Bottom-up Approach, Temporality, Social Visibility, Reputation, Socionics

    On fractional Choquard equations

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    We investigate a class of nonlinear Schrodinger equations with a generalized Choquard nonlinearity and fractional diffusion. We obtain regularity, existence, nonexistence, symmetry as well as decays properties.Comment: revised version, 22 page

    On small-noise equations with degenerate limiting system arising from volatility models

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    The one-dimensional SDE with non Lipschitz diffusion coefficient dXt=b(Xt)dt+σXtγdBt, X0=x, γ<1dX_{t} = b(X_{t})dt + \sigma X_{t}^{\gamma} dB_{t}, \ X_{0}=x, \ \gamma<1 is widely studied in mathematical finance. Several works have proposed asymptotic analysis of densities and implied volatilities in models involving instances of this equation, based on a careful implementation of saddle-point methods and (essentially) the explicit knowledge of Fourier transforms. Recent research on tail asymptotics for heat kernels [J-D. Deuschel, P.~Friz, A.~Jacquier, and S.~Violante. Marginal density expansions for diffusions and stochastic volatility, part II: Applications. 2013, arxiv:1305.6765] suggests to work with the rescaled variable Xε:=ε1/(1γ)XX^{\varepsilon}:=\varepsilon^{1/(1-\gamma)} X: while allowing to turn a space asymptotic problem into a small-ε\varepsilon problem with fixed terminal point, the process XεX^{\varepsilon} satisfies a SDE in Wentzell--Freidlin form (i.e. with driving noise εdB\varepsilon dB). We prove a pathwise large deviation principle for the process XεX^{\varepsilon} as ε0\varepsilon \to 0. As it will become clear, the limiting ODE governing the large deviations admits infinitely many solutions, a non-standard situation in the Wentzell--Freidlin theory. As for applications, the ε\varepsilon-scaling allows to derive exact log-asymptotics for path functionals of the process: while on the one hand the resulting formulae are confirmed by the CIR-CEV benchmarks, on the other hand the large deviation approach (i) applies to equations with a more general drift term and (ii) potentially opens the way to heat kernel analysis for higher-dimensional diffusions involving such an SDE as a component.Comment: 21 pages, 1 figur

    Quasielastic Versus Inelastic and Deep Inelastic Lepton Scattering in Nuclei at x > 1

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    We have made a thorough investigation of the nuclear structure function W_2A in the region of 0.8 < x < 1.5 and Q^2 < 20 GeV^2, separating the quasielastic and inelastic plus deep inelastic contributions. The agreement with present experimental data is good giving support to the results for both channels. Predictions are made in yet unexplored regions of x and Q^2 to assert the weight of the quasielastic or inelastic channels. We find that at Q^2 < 4 GeV^2 the structure function is dominated by the quasielastic contributions for x < 1.5, while for values of Q^2 > 15 GeV^2 and the range of x studied the inelastic channels are over one order of magnitude bigger than the quasielastic one. The potential of the structure function at x > 1 as a source of information on nuclear correlations is stressed once more.Comment: 17 pages, LaTeX, 13 PostScript figures, final version to be published in Nuclear Physics

    Communication between process and structure : modelling and simulating message reference networks with COM/TE

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    Focusing on observable message signs and referencing structures, communication processes can be described and analysed as message reference networks which are characterized by dynamic pattern evolution. Computational simulation provides a way of obtaining insights into the factors driving such processes. Our paper describes a theoretical framework for communication-oriented modelling — the COM approach — that is centred around the notion of social visibility as a reputation mechanism. The approach contrasts with agent-based social networks on the one hand, and with bibliometric document networks on the other. In introducing our simulation environment COM/TE, typical properties of message reference networks are discussed in terms of a case study which deals with the impact of different media and styles of communication on emergent patterns of social visibility

    Opioid receptor signaling, analgesic and side effects induced by a computationally designed pH-dependent agonist

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    Novel pain killers without adverse effects are urgently needed. Opioids induce central and intestinal side effects such as respiratory depression, sedation, addiction, and constipation. We have recently shown that a newly designed agonist with a reduced acid dissociation constant (pK(a)) abolished pain by selectively activating peripheral mu-opioid receptors (MOR) in inflamed (acidic) tissues without eliciting side effects. Here, we extended this concept in that pK(a) reduction to 7.22 was achieved by placing a fluorine atom at the ethylidene bridge in the parental molecule fentanyl. The new compound (FF3) showed pH-sensitive MOR affinity, [S-35]-GTP gamma S binding, and G protein dissociation by fluorescence resonance energy transfer. It produced injury-restricted analgesia in rat models of inflammatory, postoperative, abdominal, and neuropathic pain. At high dosages, FF3 induced sedation, motor disturbance, reward, constipation, and respiratory depression. These results support our hypothesis that a ligand's pK(a) should be close to the pH of injured tissue to obtain analgesia without side effects

    Non-perturbative dynamics of hot non-Abelian gauge fields: beyond leading log approximation

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    Many aspects of high-temperature gauge theories, such as the electroweak baryon number violation rate, color conductivity, and the hard gluon damping rate, have previously been understood only at leading logarithmic order (that is, neglecting effects suppressed only by an inverse logarithm of the gauge coupling). We discuss how to systematically go beyond leading logarithmic order in the analysis of physical quantities. Specifically, we extend to next-to-leading-log order (NLLO) the simple leading-log effective theory due to Bodeker that describes non-perturbative color physics in hot non-Abelian plasmas. A suitable scaling analysis is used to show that no new operators enter the effective theory at next-to-leading-log order. However, a NLLO calculation of the color conductivity is required, and we report the resulting value. Our NLLO result for the color conductivity can be trivially combined with previous numerical work by G. Moore to yield a NLLO result for the hot electroweak baryon number violation rate.Comment: 20 pages, 1 figur

    Low-cost reusable instrumentation for laparoendoscopic single-site nephrectomy : assessment in a porcine model

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    Purpose: To test different sets of prebent instruments and a new reusable access device for laparoendoscopic single-site (LESS) surgery. Materials and Methods: Three surgeons with previous experience in LESS performed 12 nephrectomies in six pigs. In all procedures, a multichannel access device (X-CONE_) and a 5-mm extra-long telescope were used. Four sets of prebent instruments with different profiles (S-portal_) were tested: Standard (one straight scissorsand one curved grasper), Cuschieri, Carus, and Leroy set (each of them consisting of two curved instruments with different configurations). Assessment was performed based on both objective (procedure time; time to manage the pedicle; time to free kidney) and subjective parameters (entry=exit of instruments; triangulation; dissection up=down; dissection lateral; retraction; interdependence). The subjective assessment tool used was a Likert type scale (1¼easy to 5¼prohibitive). The access device was assessed by using objective (time to completeinsertion of device after skin incision) and subjective (significant air leakage, movement constraint) parameters. Results: Time to insertion of the X-CONE was <1 minute in all the cases. Surgeons reported significant insufflant leakage in 58% of cases. The procedure was completed in 10=12 (83%) cases. Mean operative time was 8.3_4.2 minutes, being lower for the Carus group (4.5 min) and higher for the standard group (13 min). Among thedifferent sets, the standard one obtained the best mean scores for all subjective parameters. Conclusions: X-CONE allows easy abdominal access, and its reusable properties represent cost savings for LESS compared with disposable devices. Prebent instruments might also represent attractive low-cost tools for LESS
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