2,196 research outputs found

    On the probability distribution function of small scale interplanetary magnetic field fluctuations

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    In spite of a large number of papers dedicated to study MHD turbulence in the solar wind there are still some simple questions which have never been sufficiently addressed like: a)do we really know how the magnetic field vector orientation fluctuates in space? b) what is the statistics followed by the orientation of the vector itself? c) does the statistics change as the wind expands into the interplanetary space? A better understanding of these points can help us to better characterize the nature of interplanetary fluctuations and can provide useful hints to investigators who try to numerically simulate MHD turbulence. This work follows a recent paper presented by the same authors. This work follows a recent paper presented by some of the authors which shows that these fluctuations might resemble a sort of random walk governed by a Truncated Leevy Flight statistics. However, the limited statistics used in that paper did not allow final conclusions but only speculative hypotheses. In this work we aim to address the same problem using a more robust statistics which on one hand forces us not to consider velocity fluctuations but, on the other hand allows us to establish the nature of the governing statistics of magnetic fluctuations with more confidence. In addition, we show how features similar to those found in the present statistical analysis for the fast speed streams of solar wind, are qualitatively recovered in numerical simulations of the parametric instability. This might offer an alternative viewpoint for interpreting the questions raised above.Comment: 25pag, 20 jpg small size figures. In press on "ANnales Geophysicae" (September 2004

    Faktor-faktor Yang Berhubungan Dengan Response TIME Perawat Pada Penanganan Pasien Gawat Darurat Di Igd Rsup Prof. Dr . R. D. Kandou Manado

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    : Response time is dependent upon the available of speed and quality of relief to save lives or prevent disability. The purpose of this study was to identify the factors associated with the Response Time of nurses in handling emergency patients in IGD RSUP Prof. Dr. R. D. Kandou Manado. Research methods with cross sectional approach. Selection of samples with purposive sampling by 30 respondents. Independent variables including education, knowledge, duration of work and training of nurses. Instrument research using observation sheets and questionnaires. Data analysis Chi-square test at 95% significance level (α 0.05). The results showed the majority of nurses have a Response Time > 5 minutes total of 17 (56.7%). The statistical test showed there is no association between education (ρ = 0.084), knowledge (ρ = 1.000), duration of work (ρ = 0.119), and training (ρ = 0255) with a response time of nurses. Conclusion, Response time of nurses in handling emergency patients in IGD RSUP Prof. Dr. R. D. Kandou Manado average of > 5 min. Education level, knowledge, duration of work and training are not associated with the Response Time of nurses in handling emergency patients in IGD RSUP Prof. Dr. R. D. Kandou Manado. Advice to the nursing profession in order to maintain the existing standard of response time so the nursing services can be improved

    Intermittency in MHD turbulence and coronal nanoflares modelling

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    High resolution numerical simulations, solar wind data analysis, and measurements at the edges of laboratory plasma devices have allowed for a huge progress in our understanding of MHD turbulence. The high resolution of solar wind measurements has allowed to characterize the intermittency observed at small scales. We are now able to set up a consistent and convincing view of the main properties of MHD turbulence, which in turn constitutes an extremely efficient tool in understanding the behaviour of turbulent plasmas, like those in solar corona, where in situ observations are not available. Using this knowledge a model to describe injection, due to foot-point motions, storage and dissipation of MHD turbulence in coronal loops, is built where we assume strong longitudinal magnetic field, low beta and high aspect ratio, which allows us to use the set of reduced MHD equations (RMHD). The model is based on a shell technique in the wave vector space orthogonal to the strong magnetic field, while the dependence on the longitudinal coordinate is preserved. Numerical simulations show that injected energy is efficiently stored in the loop where a significant level of magnetic and velocity fluctuations is obtained. Nonlinear interactions give rise to an energy cascade towards smaller scales where energy is dissipated in an intermittent fashion. Due to the strong longitudinal magnetic field, dissipative structures propagate along the loop, with the typical speed of the Alfvén waves. The statistical analysis on the intermittent dissipative events compares well with all observed properties of nanoflare emission statistics. Moreover the recent observations of non thermal velocity measurements during flare occurrence are well described by the numerical results of the simulation model. All these results naturally emerge from the model dynamical evolution without any need of an ad-hoc hypothesis

    Sleep bruxism and sdb in albanian growing subjects: A cross-sectional study

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    BackgroundThe aim of this study was to evaluate a possible correlation between sleep bruxism and risk factors of developing obstructive sleep apnea syndrome (OSAS) in a sample of growing subjects and to assess parental awareness about sleep bruxism in their children. Methods: The sample was composed of 310 subjects (173 females and 137 males), with a mean age of 8.9 years, attending "Ndre Mjeda" school of Tirana (Albania). All parents of the children participating in the study were asked to fill in a questionnaire manually or via a digital version. The questionnaire was composed of three sections: personal data, sleep quality data, and OSAS risk factors, and it was filled out by both parents. Results: Of our samples, 41.3% presented with bruxism, and 16.5% of the parents ground their teeth. Oral breathing was reported in 11.9% of the subjects, and among these, 40% of the subjects were affected by bruxism (p > 0.05). Of the subjects, 18.7% snore overnight. Comparing it with sleep bruxism, the two phenomena are often related (p = 0.00). Conclusions: Heredity, night-sweating, nycturia, oral breathing, and snoring seem to have a significant correlation with bruxism

    The algebraic Bethe ansatz for open vertex models

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    We present a unified algebraic Bethe ansatz for open vertex models which are associated with the non-exceptional A2n(2),A2n1(2),Bn(1),Cn(1),Dn(1)A^{(2)}_{2n},A^{(2)}_{2n-1},B^{(1)}_n,C^{(1)}_n,D^{(1)}_{n} Lie algebras. By the method, we solve these models with the trivial K matrix and find that our results agree with that obtained by analytical Bethe ansatz. We also solve the Bn(1),Cn(1),Dn(1)B^{(1)}_n,C^{(1)}_n,D^{(1)}_{n} models with some non-trivial diagonal K-matrices (one free parameter case) by the algebraic Bethe ansatz.Comment: Latex, 35 pages, new content and references are added, minor revisions are mad

    A weakly nonlinear Alfvénic pulse in a transversely inhomogeneous medium

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    The interaction of a weakly nonlinear Alfvénic pulse with an Alfvén speed inhomogeneity in the direction perpendicular to the magnetic field is investigated. Identical to the phase mixing experienced by a harmonic Alfvén wave, sharp transverse gradients are generated in the pulse by the inhomogeneity. In the initial stage of the evolution of an initially plane Alfvénic pulse, the transverse gradients efficiently generate transversely propagating fast magnetoacoustic waves. However, high resolution full MHD numerical simulations of the developed stage of the pulse evolution show that the generation saturates due to destructive wave interference. It is shown that the weakly non-linear description of the generated fast magnetoacoustic wave is well described by the driven wave equation proposed in Nakariakov et al. (1997), and a simple numerical code (2D MacCromack), which solves it with minimal CPU resources, produces identical results to those obtained from the full MHD code (Lare2d, Arber et al. 2001). A parametric study of the phenomenon is undertaken, showing that, contrary to one's expectations, steeper inhomogeneities of the Alfvén speed do not produce higher saturation levels of the fast wave generation. There is a certain optimal gradient of the inhomogeneity that ensures the maximal efficiency of the fast wave generation

    On the Uq[sl(2)]{\cal{U}}_{q}[sl(2)] Temperley-Lieb reflection matrices

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    This work concerns the boundary integrability of the spin-s Uq[sl(2)]{\cal{U}}_{q}[sl(2)] Temperley-Lieb model. A systematic computation method is used to constructed the solutions of the boundary Yang-Baxter equations. For ss half-integer, a general 2s(s+1)+3/22s(s+1)+3/2 free parameter solution is presented. It turns that for ss integer, the general solution has 2s(s+1)+12s(s+1)+1 free parameters. Moreover, some particular solutions are discussed.Comment: LaTex 17 page
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