New Limit for the Half-Life of 2K(2neutrino)-Capture Decay Mode of 78Kr

Features of data accumulated at 1817 hours in the experimental search for 2K(2 \nu)-capture decay mode of Kr-78 are discussed. The new limit for this decay half-life is found to be T_{1/2} > 2.3 *10^{20} yr. (90% C.L.).Comment: 7 pages, 4 figures, submitted to Phys. of Atom. Nuc

A simple method for enhanced vibration-based structural health monitoring

This study suggests a novel method for structural vibration-based health monitoring for beams which only utilises the first natural frequency of the beam in order to detect and localise a defect. The method is based on the application of a static force in different positions along the beam. It is shown that the application of a static force on a damaged beam induces stresses at the defect which in turn cause changes in the structural natural frequencies. A very simple procedure for damage detection is suggested which uses a static force applied in just one point, in the middle of the beam. Localisation is made using two additional application points of the static force. Damage is modelled as a small notch through the whole width of the beam. The method is demonstrated and validated numerically, using a finite element model of the beam, and experimentally for a simply supported beam. Our results show that the frequency variation with the change of the force application point can be used to detect and in the same time localize very precisely even a very small defect. The method can be extended for health monitoring of other more complicated structures

A simple method for enhanced vibration-based structural health monitoring

This study suggests a novel method for structural vibration-based health monitoring for beams which only utilises the first natural frequency of the beam in order to detect and localise a defect. The method is based on the application of a static force in different positions along the beam. It is shown that the application of a static force on a damaged beam induces stresses at the defect which in turn cause changes in the structural natural frequencies. A very simple procedure for damage detection is suggested which uses a static force applied in just one point, in the middle of the beam. Localisation is made using two additional application points of the static force. Damage is modelled as a small notch through the whole width of the beam. The method is demonstrated and validated numerically, using a finite element model of the beam, and experimentally for a simply supported beam. Our results show that the frequency variation with the change of the force application point can be used to detect and in the same time localize very precisely even a very small defect. The method can be extended for health monitoring of other more complicated structures

ЕНДОГЕННІ ДЖЕРЕЛА КОНФЛІКТУ ІНТЕРЕСІВ У ДІЯЛЬНОСТІ КРЕДИТНО-РЕЙТИНГОВИХ АГЕНТСТВ

The positive effect of the functioning of credit rating agencies (CRAs) increases only if they are focused on maximizing information quality of ratings. Instead, CRAs’ reorientation to the maximization of profits in the short term can generate significant negative externalities. One of the key reasons for shifting of outlined focus could be conflicts of interest, generated by the influence of exogenous and endogenous factors. Given that the possibility of rapid and effective reduction of exogenous factors’ influence is significantly limited, the study of endogenous sources of conflicts of interest becomes relevant for their further localization and elimination.The paper identifies that the main endogenous sources of conflicts of interest could be localized both at the corporate, and operational levels of CRAs’ functioning. At the corporate level conflicts of interest are usually generated due to the existence of significant pitfalls in the models of ownership, business and financial activities, transparency, corporate governance and organizational structures of CRAs. In turn, at the operational (analyst) level the main sources of conflicts of interest are the violation of the principle of the independence of analysts and other employees of CRAs, as well as their personal interest in the manipulation with ratings.Taking into account the specifics of outlined endogenous sources in their interconnection will contribute to designing of a comprehensive system of preventive and reactive tools to manage conflicts of interest by the owners, managers, and regulators of CRAs.В статье определены, охарактеризованы и систематизированы ключевые эндогенные источники возникновения конфликтов интересов как на корпоративном, так и на операционном уровнях функционирования кредитно-рейтинговых агентств (КРА). Учет специфики определенных эндогенных источников в их взаимосвязи будет способствовать проектированию комплексной системы инструментов превентивного и реактивного управления конфликтами интересов со стороны владельцев, руководителей а также регуляторов деятельности КРА.У статті визначені, охарактеризовані та систематизовані ключові ендогенні джерела розгортання конфліктів інтересів як на корпоративному, так і на операційному рівнях функціонування кредитно-рейтингових агентств (КРА). Урахування специфіки окреслених ендогенних джерел у їх взаємозв’язку сприятиме проектуванню комплексної системи інструментів превентивного та реактивного управління конфліктами інтересів з боку власників, керівників а також регуляторів діяльності КРА

Growth, transport, and magnetic properties of Pr0.67Ca0.33MnO3 thin films

We have grown Pr0.67Ca0.33MnO3 thin films on LaAlO3 using pulsed laser deposition. Below 50 K, a field induced insulator-metal transition results in changes in resistivity of at least 6 orders of magnitude. The field induced conducting state is metastable at low temperature. The temperature dependence of the resistivity exhibits considerable hysteresis in a field of 40 kOe but becomes reversible in a field of 80 kOe

Approximate Minimum Diameter

We study the minimum diameter problem for a set of inexact points. By inexact, we mean that the precise location of the points is not known. Instead, the location of each point is restricted to a contineus region (\impre model) or a finite set of points (\indec model). Given a set of inexact points in one of \impre or \indec models, we wish to provide a lower-bound on the diameter of the real points. In the first part of the paper, we focus on \indec model. We present an $O(2^{\frac{1}{\epsilon^d}} \cdot \epsilon^{-2d} \cdot n^3 )$ time approximation algorithm of factor $(1+\epsilon)$ for finding minimum diameter of a set of points in $d$ dimensions. This improves the previously proposed algorithms for this problem substantially. Next, we consider the problem in \impre model. In $d$-dimensional space, we propose a polynomial time $\sqrt{d}$-approximation algorithm. In addition, for $d=2$, we define the notion of $\alpha$-separability and use our algorithm for \indec model to obtain $(1+\epsilon)$-approximation algorithm for a set of $\alpha$-separable regions in time $O(2^{\frac{1}{\epsilon^2}}\allowbreak . \frac{n^3}{\epsilon^{10} .\sin(\alpha/2)^3} )$

Dielectric properties of nanosilica/low-density polyethylene composites: The surface chemistry of nanoparticles and deep traps induced by nanoparticles

Four kinds of nanosilica particles with different surface modification were employed to fabricate low-density polyethylene (LDPE) composites using melt mixing and hot molding methods. The surface chemistry of modified nanosilica was analyzed by X-ray photoelectron spectroscopy. All silica nanoparticles were found to suppress the space charge injection and accumulation, increase the volume resistivity, decrease the permittivity and dielectric loss factor at low frequencies, and decrease the dielectric breakdown strength of the LDPE polymers. The modified nanoparticles, in general, showed better dielectric properties than the unmodified ones. It was found that the carrier mobility, calculated from J–V curves using the Mott-Gurney equation, was much lower for the nanocomposites than for the neat LDPE

Results of a search for 2β\beta-decay of 136^{136}Xe with high-pressure copper proportional counters in Baksan Neutrino Observatory

The experiment for the 2$\beta$-decay of $^{136}$Xe search with two high-pressure copper proportional counters has been held in Baksan neutrino observatory. The search for the process is based on comparison of spectra measured with natural and enriched xenon. No evidence has been found for 2$\beta$(2$\nu$)- and 2$\beta$(0$\nu$)-decay. The decay half lifetime limit based on data measured during 8000 h is T$_{1/2}$$\geq8.5\cdot10^{21}$yr for 2$\nu$-mode and T$_{1/2}$$\geq3.1\cdot10^{23}$yr for 0$\nu$-mode (90%C.L.).Comment: 9 pages, 8 figures; talk at the NANP'05 Conference; submitted to Phys. At. Nuc

Sub-monolayer nucleation and growth of complex oxide heterostructures at high supersaturation and rapid flux modulation

We report on the non-trivial nanoscale kinetics of the deposition of novel complex oxide heterostructures composed of a unit-cell thick correlated metal LaNiO3 and dielectric LaAlO3. The multilayers demonstrate exceptionally good crystallinity and surface morphology maintained over the large number of layers, as confirmed by AFM, RHEED, and synchrotron X-ray diffraction. To elucidate the physics behind the growth, the temperature of the substrate and the deposition rate were varied over a wide range and the results were treated in the framework of a two-layer model. These results are of fundamental importance for synthesis of new phases of complex oxide heterostructures.Comment: 13 pages, 6 figure