Resistive switching effects on the spatial distribution of phases in metal-complex oxide interfaces

In order to determine the key parameters that control the resistive switching mechanism in metal-complex oxides interfaces, we have studied the electrical properties of metal / YBa2Cu3O7-d (YBCO) interfaces using metals with different oxidation energy and work function (Au, Pt, Ag) deposited by sputtering on the surface of a YBCO ceramic sample. By analyzing the IV characteristics of the contact interfaces and the temperature dependence of their resistance, we inferred that ion migration may generate or cancel conducting filaments, which modify the resistance near the interface, in accordance with the predictions of a recent model.Comment: 3 pages, 5 figures, to be published in Physica B. Corresponding author: C. Acha ([email protected]

Studies of resistance switching effects in metal/YBa2Cu3O7-x interface junctions

Current-voltage characteristics of planar junctions formed by an epitaxial c-axis oriented YBa2Cu3O7-x thin film micro-bridge and Ag counter-electrode were measured in the temperature range from 4.2 K to 300 K. A hysteretic behavior related to switching of the junction resistance from a high-resistive to a low-resistive state and vice-versa was observed and analyzed in terms of the maximal current bias and temperature dependence. The same effects were observed on a sub-micrometer scale YBa2Cu3O7-x thin film - PtIr point contact junctions using Scanning Tunneling Microscope. These phenomena are discussed within a diffusion model, describing an oxygen vacancy drift in YBa2Cu3O7-x films in the nano-scale vicinity of the junction interface under applied electrical fields.Comment: To be published in Applied Surface Science

Intrinsic inhomogeneities and effects of resistive switching in doped manganites

The effect of resistive switching in doped manganites being in the ferromagnetic state has been studied using resistive and magneto-optic methods. The visualization of magnetic structure of La0.75Sr0.25MnO3-x single crystals, and its transformation under electric current proposed local superheating of the material above the Curie temperature, which was supported by numerical calculation. The obtained results suggest a significant role of micrometer-scale inhomogeneity of manganites in phase separation, magnetic and transport properties of the material

Determinants of foreign direct investment inflows in Namibia

Thesis (M.M. (Finance & Investment)--University of the Witwatersrand, Faculty of Commerce, Law and Management, Wits Business School, 2016This study investigates the dominant determinants of Foreign Direct Investment in Namibia. The second part of the study evaluates whether FDI received in Namibia is beneficial for the Namibian economy. The study uses two different methods to test for stationarity: Augmented Dickey-Fuller (ADF) and Phillips-Perron (PP). The study makes use of the Ordinary Least Square (OLS) in conjunction with the cointegration (CI) and Error Correction Models (ECM) to determine the factors that influence FDI in Namibia, using data for the period of 1990- 2014. The results show that, in the short-run, Foreign Direct Investment is significantly influenced by GDP, taxes, exchange rates and Drought occurrence. The results of the second part of the study were to test whether FDI received is beneficial for the Namibian economy. The Granger causality test was used to test this relationship. The results of the Granger causality test revealed that FDI is indeed beneficial for the economy. Hence, it is significant in explaining GDP in Namibia. The study recommends a review of the administration of the current investment system, which should highlight the role of each player in the economy. The study further recommends that a good quality of governance, reduced bureaucracy, low-interest rate and well-developed infrastructure will enhance investor’s confidence. Expansionary fiscal and monetary policies should be applied to stimulate GDP growth and to increase Foreign Direct Investment. Keywords: Foreign Direct Investment, Gross Domestic Product, Stationarity, Cointegration, Error Correction Modelling, Taxes and Exchange Rates.GR201

Біологічне різноманіття як об’єкт екологічних правовідносин у сфері збереження і сталого використання

Розглянуто особливості правового регулювання правовідносин у сфері збереження і сталого використання біологічного різноманіття. Вивчено положення національного й міжнародного законодавства у цій сфері, а також зміст термінів «біологічне різноманіття» і «стале використання біологічного різноманіття» з точки зору права. Проаналізовано з позицій права програмні документи, спираючись на положення яких формується державна політика у сфері збереження й використання біорізноманіття, а також місце норм щодо збереження й невиснажливого використання біорізноманіття в системі екологічного законодавства України. Обґрунтовано необхідність вироблення єдиного категорійно-понятійного апарату у сфері регулювання відносин із збереження і сталого використання біологічного різноманіття

Fast Pre-Trigger Electronics of T0/Centrality MCP-Based Start Detector for ALICE

This work describes an alternative to the current ALICE baseline solution for a TO detector, still under development. The proposed system consists of two MCP-based T0/Centrality Start Detectors (backward-forward isochronous disks) equipped with programmable, TTC synchronized front-end electronic cards (FEECs) which would be positioned along the LHC colliding beam line on both sides of the ALICE interaction region. The purpose of this arrangement, providing both precise timing and fast multiplicity selection, is to give a pre-trigger signal at the earliest possible time after a central event. This pre-trigger can be produced within 25 ns. It can be delivered within 100 ns directly to the Transition Radiation Detector and would be the earliest L0 input coming to the ALICE Central Trigger Processor. A noise-free passive multichannel summator of 2ns signals is used to provide a determination of the collision time with a potential accuracy better than 10 ps in the case of Pb-Pb collisions, the limit coming from the electronics. Results from in-beam tests confirm the functionality of the main elements. Further development plans are presented