Low Energy Properties of the Kondo chain in the RKKY regime

We study the Kondo chain in the regime of high spin concentration where the low energy physics is dominated by the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction. As has been recently shown (A. M. Tsvelik and O. M. Yevtushenko, Phys. Rev. Lett 115, 216402 (2015)), this model has two phases with drastically different transport properties depending on the anisotropy of the exchange interaction. In particular, the helical symmetry of the fermions is spontaneously broken when the anisotropy is of the easy plane type (EP). This leads to a parametrical suppression of the localization effects. In the present paper we substantially extend the previous theory, in particular, by analyzing a competition of forward- and backward- scattering, including into the theory short range electron interactions and calculating spin correlation functions. We discuss applicability of our theory and possible experiments which could support the theoretical findings.Comment: 24 pages, 8 figures, 5 appendice

Anderson localization transition with long-ranged hoppings : analysis of the strong multifractality regime in terms of weighted Levy sums

For Anderson tight-binding models in dimension $d$ with random on-site energies $\epsilon_{\vec r}$ and critical long-ranged hoppings decaying typically as $V^{typ}(r) \sim V/r^d$, we show that the strong multifractality regime corresponding to small $V$ can be studied via the standard perturbation theory for eigenvectors in quantum mechanics. The Inverse Participation Ratios $Y_q(L)$, which are the order parameters of Anderson transitions, can be written in terms of weighted L\'evy sums of broadly distributed variables (as a consequence of the presence of on-site random energies in the denominators of the perturbation theory). We compute at leading order the typical and disorder-averaged multifractal spectra $\tau_{typ}(q)$ and $\tau_{av}(q)$ as a function of $q$. For $q<1/2$, we obtain the non-vanishing limiting spectrum $\tau_{typ}(q)=\tau_{av}(q)=d(2q-1)$ as $V \to 0^+$. For $q>1/2$, this method yields the same disorder-averaged spectrum $\tau_{av}(q)$ of order $O(V)$ as obtained previously via the Levitov renormalization method by Mirlin and Evers [Phys. Rev. B 62, 7920 (2000)]. In addition, it allows to compute explicitly the typical spectrum, also of order $O(V)$, but with a different $q$-dependence $\tau_{typ}(q) \ne \tau_{av}(q)$ for all $q>q_c=1/2$. As a consequence, we find that the corresponding singularity spectra $f_{typ}(\alpha)$ and $f_{av}(\alpha)$ differ even in the positive region $f>0$, and vanish at different values $\alpha_+^{typ} > \alpha_+^{av}$, in contrast to the standard picture. We also obtain that the saddle value $\alpha_{typ}(q)$ of the Legendre transform reaches the termination point $\alpha_+^{typ}$ where $f_{typ}(\alpha_+^{typ})=0$ only in the limit $q \to +\infty$.Comment: 13 pages, 2 figures, v2=final versio

Drastic facilitation of the onset of global chaos in a periodically driven Hamiltonian system due to an extremum in the dependence of eigenfrequency on energy

The Chirikov resonance-overlap criterion predicts the onset of global chaos if nonlinear resonances overlap in energy, which is conventionally assumed to require a non-small magnitude of perturbation. We show that, for a time-periodic perturbation, the onset of global chaos may occur at unusually {\it small} magnitudes of perturbation if the unperturbed system possesses more than one separatrix. The relevant scenario is the combination of the overlap in the phase space between resonances of the same order and their overlap in energy with chaotic layers associated with separatrices of the unperturbed system. One of the most important manifestations of this effect is a drastic increase of the energy range involved into the unbounded chaotic transport in spatially periodic system driven by a rather {\it weak} time-periodic force, provided the driving frequency approaches the extremal eigenfrequency or its harmonics. We develop the asymptotic theory and verify it in simulations.Comment: 5 pages, 4 figures, LaTeX, to appear PR

Прогностичне значення маркерів ендотеліальної дисфункції в діагностиці ступеня атеросклеротичного ураження коронарних судин у хворих із гострим інфарктом міокарда з коронарним стентуванням

Мета. Оцінити рівні інгібітора активатора плазміногену 1 типу (ІАП-1) та асиметричного діметіларгініну (АДМА) у хворих із гострим інфарктом міокарда (ГІМ) в залежності від наявності або відсутності цукрового діабету 2-го типу (ЦД2) та характеру ураження коронарних артерій (KА), а також їх прогностичне значення щодо ступеня атеросклеротичного ураження коронарних судин. Матеріали і методи. Обстежено 130 хворих, 44 (33,85%) жінки та 86 (66,15%) чоловіків. Усіх пацієнтів розподілено на дві групи: основну - 73 хворих із ГІМ і супутнім ЦД2, серед них 43 чоловіки і 30 жінок, середній вік яких становив (62,73 ± 1,39) року, та порівняльну - 57 хворих із ГІМ без ЦД2, серед них 43 чоловіки і 14 жінок, середній вік яких становив (63,98 ± 1,47) року. Контрольну групу склали 20 практично здорових осіб (10 чоловіків і 10 жінок, середній вік яких становив (60,85 ± 1,37) року). Усім хворим проводили коронарографію вінцевих судин серця у стандартних проекціях за допомогою ангіографа Siemens Axiom Artis. Вміст АДМА встановлювали імуноферментним методом, використовуючи комерційну систему тестування «Immunodiagnostik» компанії ADMA Xpress ELISA Kit (Австрія), ІАП-1 - також імуноферментним методом, використовуючи комерційну тест-систему виробництва фірми Technoclone PAI-1 ELISA Kit (Австрія). Результати. У хворих із ГІМ незалежно від того, мали вони ЦД2 чи не мали, рівні ІАП-1 та АДМА підвищені у порівнянні з контрольною групою (р < 0,05). У хворих з гемодинамічно значущим стенозом (ГЗC) KА (70% і більше) визначено підвищення рівнів ІАП-1 та АДМА як за наявності, так і за відсутності ЦД2 (р < 0,05).У хворих із ГІМ та дифузним ураженням (ДУ) KА як із супутнім ЦД2, так і без нього рівні ІАП-1 та АДМА були достовірно вище, ніж у хворих без ДУ KА (р < 0,05). Висновки. Порівняння площ під ROC-кривими показало, що більшу діагностичну цінність для прогнозування ДУ KА у хворих із ГІМ та супутнім ЦД2 має ІАП-1, ніж АДМА. Рівні ІАП-1 та АДМА доцільно визначати для прогнозування ГЗC KА та діагностики ДУ коронарного русла з тим, щоб проводити профілактику розвитку ускладнень ГІМ

Surgical methods of prophylaxis of primary insufficiency of the bronchus stump sutures

Objective. To elaborate the effective  miniinvasive technically simple method of prophylaxis for primary insufficiency of the bronchus stump sutures (BSS) due to accomplishment of its transthoracic hermetization and creation of conditions for reduction of impact of the air-wave stream through the resected bronchus lumen onto the suture. Materials and methods. Complex analysis of the treatment results was conducted in 123 patients, in whom pulmonary resection or pulmonectomy was performed. All the patients were divided into two groups: comparative (n=66) and the main (n=57). In patients of the main group the elaborated procedures were applied, concerning determination of the occurrence risk for primary insufficiency of BSS and surgical measures for prophylaxis of this complication. Results. After estimation of risk for the primary insufficiency of the BSS occurrence in 41 patients of the main group the proposed two-staged surgical procedure was applied: endobronchial implantation of allotransplant into the zone of the resection and its mechanical suturing (stage I), and the bronchus stump covering, using bioactive bandage with additional fixing, using monofilament threads (stage II). In the main group the development of primary insufficiency was observed in 2 (3.51%) patients, no one patient died. In the comparison group primary insufficiency of BSS have occurred in 6 (9.09%) patients, and mortality have constituted 3.03%. Conclusion. Application of original method of surgical prophylaxis of the BSSI made it possible to reduce its occurrence rate in 2,6 times and escaping of mortality

Ways of enhancement of the surgical treatment efficacy in treatment of patients, suffering pulmonary tumors

Objective. Efficacy of endoscopic bronchosanation for prophylaxis of preoperative and postoperative complications in patients with pulmonary tumors. Маterials and methods. There was studied the efficacy of endoscopic photodynamic therapy in accordance to procedure, elaborated by the authors, including injection of the water solution of a methylene blue dye in concentration 0.04% into tracheobronchial tree, irradiated by laser with the wave length 0.63 mcm, independently and in conjunction with a standard anti-inflammatory therapy as preoperative preparation of tracheobronchial tree in patients, suffering pulmonary cancer. In the investigation 181 patients were included, suffering pulmonary cancer Stages II-III, morphologically confirmed, and with coexistent endobronchitis. Results. In accordance to analysis of the pathogenic microflora titer and character in lumen of bronchial tree after preoperative preparation there was established, that while application of independent endoscopic bronchosanation in 55 (87%) observations the pathogenic microflora was absent. While combination of photodynamical bronchosanation in accordance to standard therapy a pathogenic microflora was not revealed in 52 patients. While conduction of a standard preparation without application of a laser therapy microflora was not revealed only in 44.8% observations. Together with the bronchial mucosa metaplasia in some investigated patients the dysplastic changes of bronchial epithelium of various severity degree were registered. Independent endoscopic bronchosanation have leaded to trustworthy lowering of a general rate of the bronchial epithelial dysplasia in the patients tо 36.1%, together with standard anti-inflammatory therapy - tо 42.4%. Conclusion. Application of endoscopic photodynamic bronchosanation in accordance to the proposed procedure in preoperative period in the patients with objective to correct a concomitant endobronchitis, as independent option or together with standard anti-inflammatory therapy, leads to reduction  of the endobronchial complications rate after operative treatment for pulmonary cancer, comparing with a control group. Еndoscopic bronchosanation is accompanied by significant lowering of severity of endoscopic signs of coexistent endobronchitits and improvement of mucociliary transport. In accordance to microbiological tests in 87 - 88% of patients a complete sanation of bronchial tree and elimination of main histological criteria of inflammation were noted, while in 67.2 - 100% patients – restoration of normal structure of the bronchial tree mucosa

Ендоскопічні методи дренування хронічних абсцесів легенів та оцінка їх ефективності за допомогою сонографії

Мета. Оцінити за допомогою сонографії ефективність ендоскопічних методів дренування хронічних абсцесів легенів. Матеріали і методи. На базі клініки Інституту проведено обстеження та лікування 98 хворих з хронічними абсцесами легенів. Хворих розподілили на дві групи: основну та порівняльну. Хворим основної групи разом із протизапальними препаратами системно та місцево призначали ліпосомальний препарат ліпін. У хворих порівняльної групи застосовували cтандартні методи. Результати. Ефективність ендоскопічного дренування порожнини хронічних абсцесів доведена позитивною ультразвуковою (УЗ) динамікою в більш ранні строки, ніж у разі застосування стандартних методів лікування. На підставі аналізу лабораторних показників встановлено суттєвий позитивний вплив застосованої методики на зниження рівня показників ендогенної інтоксикації. Висновки. Результати свідчать про ефективність запропонованого методу ендоскопічного дренування порожнини хронічного абсцесу разом із комбінованою протизапальною терапією з використанням препарату ліпін та його перевагу перед стандартними схемами лікування

Quasiclassical magnetotransport in a random array of antidots

We study theoretically the magnetoresistance $\rho_{xx}(B)$ of a two-dimensional electron gas scattered by a random ensemble of impenetrable discs in the presence of a long-range correlated random potential. We believe that this model describes a high-mobility semiconductor heterostructure with a random array of antidots. We show that the interplay of scattering by the two types of disorder generates new behavior of $\rho_{xx}(B)$ which is absent for only one kind of disorder. We demonstrate that even a weak long-range disorder becomes important with increasing $B$. In particular, although $\rho_{xx}(B)$ vanishes in the limit of large $B$ when only one type of disorder is present, we show that it keeps growing with increasing $B$ in the antidot array in the presence of smooth disorder. The reversal of the behavior of $\rho_{xx}(B)$ is due to a mutual destruction of the quasiclassical localization induced by a strong magnetic field: specifically, the adiabatic localization in the long-range Gaussian disorder is washed out by the scattering on hard discs, whereas the adiabatic drift and related percolation of cyclotron orbits destroys the localization in the dilute system of hard discs. For intermediate magnetic fields in a dilute antidot array, we show the existence of a strong negative magnetoresistance, which leads to a nonmonotonic dependence of $\rho_{xx}(B)$.Comment: 21 pages, 13 figure

Energy level statistics of a critical random matrix ensemble

We study level statistics of a critical random matrix ensemble of a power-law banded complex Hermitean matrices. We compute numerically the level compressibility via the level number variance and compare it with the analytical formula for the exactly solvable model of Moshe, Neuberger and Shapiro.Comment: 8 pages, 3 figure

Broken symmetries and directed collective energy transport

We study the appearance of directed energy current in homogeneous spatially extended systems coupled to a heat bath in the presence of an external ac field E(t). The systems are described by nonlinear field equations. By making use of a symmetry analysis we predict the right choice of E(t) and obtain directed energy transport for systems with a nonzero topological charge Q. We demonstrate that the symmetry properties of motion of topological solitons (kinks and antikinks) are equivalent to the ones for the energy current. Numerical simulations confirm the predictions of the symmetry analysis and, moreover, show that the directed energy current drastically increases as the dissipation parameter $\alpha$ reduces. Our results generalize recent rigorous theories of currents generated by broken time-space symmetries to the case of interacting many-particle systems.Comment: 4 pages, 2 figure