407 research outputs found

    Удосконалення форм, методів та організаційних засад здійснення цивільного контролю за діяльністю органів прокуратури

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    Сімонян, Н. А. Удосконалення форм, методів та організаційних засад здійснення цивільного контролю за діяльністю органів прокуратури / Сімонян Наіра Арсенівна // Наше право. - 2013. - № 9. - С. 20-24.У статті проаналізовано проблемні питання реалізації форм і методів контролю за діяльністю органів прокуратури, з'ясовано проблемні питання організації громадянського контролю, визначено найважливіші напрями вдосконалення організаційних засад здійснення цивільного контролю за діяльністю органів прокуратури. The article analyzes the problematic issues of the implementation of forms and methods of civil control over the activities of the prosecutor's office, clarifies the problematic issues of organizing civil control, identifies the most important directions for improving the organizational foundations of civil control over the activities of the prosecutor's office. В статье проанализированы проблемные вопросы реализации форм и методов гражданского контроля за деятельностью органов прокуратуры, выяснены проблемные вопросы организации гражданского контроля, определены важнейшие направления совершенствования организационных основ осуществления гражданского контроля за деятельностью органов прокуратуры

    Universality at integer quantum Hall transitions

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    We report in this paper results of experimental and theoretical studies of transitions between different integer quantum Hall phases, as well as transition between the insulating phase and quantum Hall phases at high magnetic fields. We focus mainly on universal properties of the transitions. We demonstrate that properly defined conductivity tensor is universal at the transitions. We also present numerical results of a non-interacting electron model, which suggest that the Thouless conductance is universal at integer quantum Hall transitions, just like the conductivity tensor. Finite temperature and system size effects near the transition point are also studied.Comment: 20 pages, 15 figure

    Hopping Conduction in Uniaxially Stressed Si:B near the Insulator-Metal Transition

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    Using uniaxial stress to tune the critical density near that of the sample, we have studied in detail the low-temperature conductivity of p-type Si:B in the insulating phase very near the metal-insulator transition. For all values of temperature and stress, the conductivity collapses onto a single universal scaling curve. For large values of the argument, the scaling function is well fit by the exponentially activated form associated with variable range hopping when electron-electron interactions cause a soft Coulomb gap in the density of states at the Fermi energy. The temperature dependence of the prefactor, corresponding to the T-dependence of the critical curve, has been determined reliably for this system, and is proportional to the square-root of T. We show explicitly that nevlecting the prefactor leads to substantial errors in the determination of the scaling parameters and the critical exponents derived from them. The conductivity is not consistent with Mott variable-range hopping in the critical region nor does it obey this form for any range of the parameters. Instead, for smaller argument of the scaling function, the conductivity of Si:B is well fit by an exponential form with exponent 0.31 related to the critical exponents of the system at the metal- insulator transition.Comment: 13 pages, 6 figure

    Metal-insulator transition at B=0 in a dilute two dimensional GaAs-AlGaAs hole gas

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    We report the observation of a metal insulator transition at B=0 in a high mobility two dimensional hole gas in a GaAs-AlGaAs heterostructure. A clear critical point separates the insulating phase from the metallic phase, demonstrating the existence of a well defined minimum metallic conductivity sigma(min)=2e/h. The sigma(T) data either side of the transition can be `scaled' on to one curve with a single parameter (To). The application of a parallel magnetic field increases sigma(min) and broadens the transition. We argue that strong electron-electron interactions (rs = 10) destroy phase coherence, removing quantum intereference corrections to the conductivity.Comment: 4 pages RevTex + 4 figures. Submitted to PRL. Originally posted 22 September 1997. Revised 12 October 1997 - minor changes to referencing, figure cations and figure

    Aluminum Oxide Layers as Possible Components for Layered Tunnel Barriers

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    We have studied transport properties of Nb/Al/AlOx/Nb tunnel junctions with ultrathin aluminum oxide layers formed by (i) thermal oxidation and (ii) plasma oxidation, before and after rapid thermal post-annealing of the completed structures at temperatures up to 550 deg C. Post-annealing at temperatures above 300 deg C results in a significant decrease of the tunneling conductance of thermally-grown barriers, while plasma-grown barriers start to change only at annealing temperatures above 450 deg C. Fitting the experimental I-V curves of the junctions using the results of the microscopic theory of direct tunneling shows that the annealing of thermally-grown oxides at temperatures above 300 deg C results in a substantial increase of their average tunnel barriers height, from ~1.8 eV to ~2.45 eV, versus the practically unchanged height of ~2.0 eV for plasma-grown layers. This difference, together with high endurance of annealed barriers under electric stress (breakdown field above 10 MV/cm) may enable all-AlOx and SiO2/AlOx layered "crested" barriers for advanced floating-gate memory applications.Comment: 7 pages, 6 figure

    Universal scaling, beta function, and metal-insulator transitions

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    We demonstrate a universal scaling form of longitudinal resistance in the quantum critical region of metal-insulator transitions, based on numerical results of three-dimensional Anderson transitions (with and without magnetic field), two-dimensional quantum Hall plateau to insulator transition, as well as experimental data of the recently discovered two-dimensional metal-insulator transition. The associated reflection symmetry and a peculiar logarithmic form of the beta function exist over a wide range in which the resistance can change by more than one order of magnitude. Interesting implications for the two-dimensional metal-insulator transition are discussed.Comment: 4 pages, REVTEX, 4 embedded figures; minor corrections to figures and tex

    Scaling theory of two-dimensional metal-insulator transitions

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    We discuss the recently discovered two-dimensional metal-insulator transition in zero magnetic field in the light of the scaling theory of localization. We demonstrate that the observed symmetry relating conductivity and resistivity follows directly from the quantum critical behavior associated with such a transition. In addition, we show that very general scaling considerations imply that any disordered two dimensional metal is a perfect metal, but most likely not a Fermi liquid.Comment: 4 pages, no figures, REVTEX. Minor corrections adde

    On large deviation properties of Erdos-Renyi random graphs

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    We show that large deviation properties of Erd\"os-R\'enyi random graphs can be derived from the free energy of the qq-state Potts model of statistical mechanics. More precisely the Legendre transform of the Potts free energy with respect to lnq\ln q is related to the component generating function of the graph ensemble. This generalizes the well-known mapping between typical properties of random graphs and the q1q\to 1 limit of the Potts free energy. For exponentially rare graphs we explicitly calculate the number of components, the size of the giant component, the degree distributions inside and outside the giant component, and the distribution of small component sizes. We also perform numerical simulations which are in very good agreement with our analytical work. Finally we demonstrate how the same results can be derived by studying the evolution of random graphs under the insertion of new vertices and edges, without recourse to the thermodynamics of the Potts model.Comment: 38 pages, 9 figures, Latex2e, corrected and extended version including numerical simulation result

    Magnetoresistance and electronic structure of asymmetric GaAs/AlGaAs double quantum wells in the in-plane/tilted magnetic field

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    Bilayer two-dimensional electron systems formed by a thin barrier in the GaAs buffer of a standard heterostructure were investigated by magnetotransport measurements. In magnetic fields oriented parallel to the electron layers, the magnetoresistance exhibits an oscillation associated with the depopulation of the higher occupied subband and the field-induced transition into a decoupled bilayer. Shubnikov-de Haas oscillations in slightly tilted magnetic fields allow to reconstruct the evolution of the electron concentration in the individual subbands as a function of the in-plane magnetic field. The characteristics of the system derived experimentally are in quantitative agreement with numerical self-consistent-field calculations of the electronic structure.Comment: 6 pages, 5 figure

    Thermal (in)stability of type I collagen fibrils

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    We measured Young's modulus at temperatures ranging from 20 to 100 ^{\circ}Cforacollagenfibriltakenfromratstendon.Thehydrationchangeunderheatingandthedampingdecrementweremeasuredaswell.AtphysiologicaltemperaturesC for a collagen fibril taken from rat's tendon. The hydration change under heating and the damping decrement were measured as well. At physiological temperatures 25-45^{\circ}CYoungsmodulusdecreases,whichcanbeinterpretedasinstabilityofcollagen.FortemperaturesbetweenC Young's modulus decreases, which can be interpreted as instability of collagen. For temperatures between 45-80^{\circ}CYoungsmodulusfirststabilizesandthenincreaseswithdecreasingthetemperature.ThehydratedwatercontentandthedampingdecrementhavestrongmaximaintheintervalC Young's modulus first stabilizes and then increases with decreasing the temperature. The hydrated water content and the damping decrement have strong maxima in the interval 70-80^{\circ}Cindicatingoncomplexintermolecularstructuralchangesinthefibril.AlltheseeffectsdisappearafterheatdenaturatingthesampleatC indicating on complex inter-molecular structural changes in the fibril. All these effects disappear after heat-denaturating the sample at 120^\circ$C. Our main result is a five-stage mechanism by which the instability of a single collagen at physiological temperatures is compensated by the interaction between collagen molecules within the fibril.Comment: 4 pages, 4 figure
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