135 research outputs found

    Localization-delocalization transition on a separatrix system of nonlinear Schrodinger equation with disorder

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    Localization-delocalization transition in a discrete Anderson nonlinear Schr\"odinger equation with disorder is shown to be a critical phenomenon −- similar to a percolation transition on a disordered lattice, with the nonlinearity parameter thought as the control parameter. In vicinity of the critical point the spreading of the wave field is subdiffusive in the limit t→+∞t\rightarrow+\infty. The second moment grows with time as a powerlaw ∝tα\propto t^\alpha, with α\alpha exactly 1/3. This critical spreading finds its significance in some connection with the general problem of transport along separatrices of dynamical systems with many degrees of freedom and is mathematically related with a description in terms fractional derivative equations. Above the delocalization point, with the criticality effects stepping aside, we find that the transport is subdiffusive with α=2/5\alpha = 2/5 consistently with the results from previous investigations. A threshold for unlimited spreading is calculated exactly by mapping the transport problem on a Cayley tree.Comment: 6 pages, 1 figur

    E-pile model of self-organized criticality

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    The concept of percolation is combined with a self-consistent treatment of the interaction between the dynamics on a lattice and the external drive. Such a treatment can provide a mechanism by which the system evolves to criticality without fine tuning, thus offering a route to self-organized criticality (SOC) which in many cases is more natural than the weak random drive combined with boundary loss/dissipation as used in standard sand-pile formulations. We introduce a new metaphor, the e-pile model, and a formalism for electric conduction in random media to compute critical exponents for such a system. Variations of the model apply to a number of other physical problems, such as electric plasma discharges, dielectric relaxation, and the dynamics of the Earth's magnetotail.Comment: 4 pages, 2 figure

    Fracton pairing mechanism for "strange" superconductors: Self-assembling organic polymers and copper-oxide compounds

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    Self-assembling organic polymers and copper-oxide compounds are two classes of "strange" superconductors, whose challenging behavior does not comply with the traditional picture of Bardeen, Cooper, and Schrieffer (BCS) superconductivity in regular crystals. In this paper, we propose a theoretical model that accounts for the strange superconducting properties of either class of the materials. These properties are considered as interconnected manifestations of the same phenomenon: We argue that superconductivity occurs in the both cases because the charge carriers (i.e., electrons or holes) exchange {\it fracton excitations}, quantum oscillations of fractal lattices that mimic the complex microscopic organization of the strange superconductors. For the copper oxides, the superconducting transition temperature TcT_c as predicted by the fracton mechanism is of the order of ∌150\sim 150 K. We suggest that the marginal ingredient of the high-temperature superconducting phase is provided by fracton coupled holes that condensate in the conducting copper-oxygen planes owing to the intrinsic field-effect-transistor configuration of the cuprate compounds. For the gate-induced superconducting phase in the electron-doped polymers, we simultaneously find a rather modest transition temperature of ∌(2−3)\sim (2-3) K owing to the limitations imposed by the electron tunneling processes on a fractal geometry. We speculate that hole-type superconductivity observes larger onset temperatures when compared to its electron-type counterpart. This promises an intriguing possibility of the high-temperature superconducting states in hole-doped complex materials. A specific prediction of the present study is universality of ac conduction for T≳TcT\gtrsim T_c.Comment: 12 pages (including separate abstract page), no figure

    RESVERATROL IN KUBAN WINES

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    Purpose: The main purpose of viticulture is to improve the quality of the grapes, both to a greater extent for ampelotherapy and winemaking, and, to a lesser extent, to onotherapy. Methodology: The article highlights the results of perennial (from 2014) studies of 18 promising technical grape varieties from different zones of the Krasnodar Territory: Anapo-Taman, Central, as well as Amur from the Black Sea zone of the Krasnodar Territory and two control Western European world-famous and most common varieties Merlot and Cabernet-Sauvignon in the same zones. Result: The average values of resveratrol were found in wine materials from the varieties Vladimir and Dmitry (4.7 mg / dm3), Podlesny (3.9 mg / dm3), Saperavi Severny (3.5 mg / dm3), 40 let Octiabria (3.3 mg / dm3), Kurchansky and 40 let Pobedy (3.0 and 2.9 mg / dm3, respectively). On the other hand, as shown by the analysis of wine materials, the Antaris, Varyushkin, Mitsar and Plechistik varieties synthesize a lower content of resveratrol (1.0 and 0.9 mg / dm3, respectively). Applications: This research can be used for the universities, teachers and education students. Novelty/Originality: In this research, the model of resveratrol in Kuban wines is presented in a comprehensive and complete manner

    Nutritional Status Disorders in Chronic Kidney Disease: Practical Aspects (Systematic Review)

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    Despite the significant achievements in the management of chronic kidney disease (CKD) patients, the mortality rate of these patients still remains high. Nutritional status disorders (NSD) are considered now as one of the prognostic risk factors not only for dialysis but also for predialysis CKD stages. Since the publication of KDIGO 2012 guidelines for CKD patient’s management, there has been some significant advancement in our understanding of main NSD mechanisms in CKD, including different nosological group patients (first, in diabetic and systemic diseases patients). At the same time, there is still an urgent need for randomized trials for better-informed decisions and future optimization of CKD patients’ care. This chapter provides the current data on all aspects of NSD in CKD: etiology, diagnosis, prevention, and treatment approaches, as well as on risk factors of NSD at predialysis stages and in chronic hemodialysis patients. Considerable attention was devoted to the diagnosis and differential diagnosis of NSD in CKD patients. It was determined that the overall strategy for dietary treatment contributed to improving the life quality of patients and slowing down of CKD progression. The review is written based on the published results of clinical studies performed on the position of evidence-based medicine

    Disorders in the System of Mineral and Bone Metabolism Regulators—FGF-23, Klotho and Sclerostin—in Chronic Kidney Disease: Clinical Significance and Possibilities for Correction

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    The chapter discusses the current understanding of the system of mineral and bone metabolism regulators—FGF-23, Klotho and sclerostin—disturbances in chronic kidney disease (CKD). In the chapter we presented the date, including our own results, which allow to suggest the change in the ratio of FGF-23-Klotho-sclerostin in CKD as an early biomarker not only for the chronic kidney damage but also for high cardiovascular (CV) risk. Results of studies show that disorders in FGF-23-Klotho-sclerostin ratio correlate with the frequency and severity of hypertension, vascular calcification, cardiac remodelling, anaemia, malnutrition, inflammation and strong aggravate CV risk in CKD. It was found independent from blood pressure (BP) action of increased serum FGF-23 on the myocardium as well as the correlation of serum high-sensitive troponin I with increased serum FGF-23 and low Klotho levels in CKD patients. At the same time, it was shown that renoprotective therapy, including renin-angiotensin blockers, low-protein diet with amino/keto acid supplementation and phosphate binders, erythropoiesis stimulators, vitamin D metabolites used to get the target levels of BP, serum phosphorus, haemoglobin, parathyroid hormone and nutritional status disorders correction can reduce the risk of CV events, as the major cause of death in CKD patients

    Quality of life of chronic kidney disease patients on renal replacement therapy

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    The study demonstrated the results of the comparative analysis of various types of renal replacement therapy effects on the quality of life patients with terminal stage of chronic kidney disease on the basis of standardized questionnaires. It has been shown that the quality of life is significantly improved after a kidney transplantation. At the same time, it has also been found that the introduction of home dialysis, epoetins, active metabolites of vitamin D, calcimimetics in the clinic care expanded the opportunities for the labor rehabilitation of the dialysis patients and made their quality of life comparable with the same of the kidney transplant recipients

    A nonextensive entropy approach to solar wind intermittency

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    The probability distributions (PDFs) of the differences of any physical variable in the intermittent, turbulent interplanetary medium are scale dependent. Strong non-Gaussianity of solar wind fluctuations applies for short time-lag spacecraft observations, corresponding to small-scale spatial separations, whereas for large scales the differences turn into a Gaussian normal distribution. These characteristics were hitherto described in the context of the log-normal, the Castaing distribution or the shell model. On the other hand, a possible explanation for nonlocality in turbulence is offered within the context of nonextensive entropy generalization by a recently introduced bi-kappa distribution, generating through a convolution of a negative-kappa core and positive-kappa halo pronounced non-Gaussian structures. The PDFs of solar wind scalar field differences are computed from WIND and ACE data for different time lags and compared with the characteristics of the theoretical bi-kappa functional, well representing the overall scale dependence of the spatial solar wind intermittency. The observed PDF characteristics for increased spatial scales are manifest in the theoretical distribution functional by enhancing the only tuning parameter Îș\kappa, measuring the degree of nonextensivity where the large-scale Gaussian is approached for Îș→∞\kappa \to \infty. The nonextensive approach assures for experimental studies of solar wind intermittency independence from influence of a priori model assumptions. It is argued that the intermittency of the turbulent fluctuations should be related physically to the nonextensive character of the interplanetary medium counting for nonlocal interactions via the entropy generalization.Comment: 17 pages, 7 figures, accepted for publication in Astrophys.
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