Temperature dependence of the resistance switching effect studied on the metal/YBa2Cu3O6+x planar junctions

Resistive switching (RS) effect observed in capacitor-like metal/insulator/metal junctions belongs to the most promising candidates for next generation of memory cell technology. It is based upon a sudden change of the junction resistance caused by an electric field applied to the metal electrodes. The aim of this work was to study this effect on the structure metal/YBCO6/YBCO7, where YBCO7 is a metallic phase and YBCO6 is an insulator phase which arises spontaneously by out-diffusion of oxygen from a few nanometers wide YBCO surface layer. Oriented YBa2Cu3O7 thin films were prepared by the method of magnetron sputtering and consequently planar structures with metal-YBCO junction were made by the means of the optical lithography, ion etching and vacuum evaporation. On these junctions we have studied the temperature dependence of the RS effect with I-V and dI/dV-V transport measurements down to liquid He temperature. We have determined temperature dependence of the RS effect threshold voltage in the temperature range 100-300 K and showed that this dependency is compatible with common idea of oxygen ions migration under electric field within the YBCO surface layer.Comment: 13 pages, 5 figure

Andersen-Tawil syndrome: report of 3 novel mutations and high risk of symptomatic cardiac involvement.

IntroductionAndersen-Tawil syndrome (ATS) is a potassium channelopathy affecting cardiac and skeletal muscle. Periodic paralysis is a presenting symptom in some patients, whereas, in others, symptomatic arrhythmias or prolongation of QT in echocardiographic recordings will lead to diagnosis of ATS. Striking intrafamilial variability of expression of KCNJ2 mutations and rarity of the syndrome may lead to misdiagnosis.MethodsWe report 15 patients from 8 Polish families with ATS, including 3 with novel KCNJ2 mutations.ResultsAll patients had dysmorphic features; periodic paralysis affected males more frequently than females (80% vs. 20%), and most attacks were normokalemic. Two patients (with T75M and T309I mutations) had aborted sudden cardiac death. An implantable cardioverter-defibrillator was utilized in 40% of cases.ConclusionsKCNJ2 mutations cause a variable phenotype, with dysmorphic features seen in all patients studied, a high penetrance of periodic paralysis in males and ventricular arrhythmia with a risk of sudden cardiac death

Nanogranular MgB2 thin films on SiC buffered Si substrates prepared by in-situ method

MgB2 thin films were deposited on SiC buffered Si substrates by sequential electron beam evaporation of B-Mg bilayer followed by in-situ annealing. The application of a SiC buffer layer enables the maximum annealing temperature of 830 C. The Transmission Electron Microscopy analysis confirms the growth of a nanogranular MgB2 film and the presence of a Mg2Si compound at the surface of the film. The 150-200 nm thick films show a maximum zero resistance critical temperature TC0 above 37 K and a critical current density JC ~ 106 A/cm2 at 11K.Comment: 7 pages, 6 figures, submitted to Applied Physics Letter

Booter websites characterization: towards a list of threats

Distributed Denial of Service (DDoS) attacks mean millions in revenue losses to many industries, such e-commerce and online financial services. The amount of reported DDoS attacks has increased with 47% compared to 2013. One of the reasons for this increase is the availability and ease of accessibility to websites, which provide DDoS attacks as a paid service, called Booters. Although there are hundreds of Booters available, current researches are focused on a handful sample of them - either to analyse attack traffic or hacked databases. Towards a thorough understanding and mitigation of Booters, a comprehensive list of them is needed. In this paper we characterize Booter websites and demonstrate that the found main characteristics can be used to classify Booters with 85% of accuracy. The Dutch National Research and Education Network (SURFnet) has been using a list generated by our methodology since 2013, what demonstrates high relevance to the network management community and the security specialists

Anatomy of three-body decay III. Energy distributions

We address the problem of calculating momentum distributions of particles emerging from the three-body decay of a many-body resonance. We show that these distributions are determined by the asymptotics of the coordinate-space complex-energy wave-function of the resonance. We use the hyperspherical adiabatic expansion method where all lengths are proportional to the hyperradius. The structures of the resonances are related to different decay mechanisms. For direct decay all inter-particle distances increase proportional to the hyperradius at intermediate and large distances. Sequential three-body decay proceeds via spatially confined quasi-stationary two-body configurations. Then two particles remain close while the third moves away. The wave function may contain mixtures which produce coherence effects at small distances, but the energy distributions can still be added incoherently. Two-neutron halos are discussed in details and illustrated by the $2^+$ resonance in $^{6}$He. The dynamic evolution of the decay process is discussed.Comment: 30 pages, 8 figures, to be published in Nuclear Physics

Three-body structure of the low-lying 17^{17}Ne-states

The Borromean nucleus $^{17}$Ne ($^{15}$O$+ p + p$) is investigated by using the hyperspheric adiabatic expansion for a a three-body system. The measured size of $^{15}$O and the low-lying resonances of $^{16}$F ($^{15}$O$+ p$) are first used as constraints to determine both central and spin-dependent two-body interactions. Then, the ground state structure of $^{17}$Ne is found to be an almost equal mixture of $s^2$ and $d^2$ proton-$^{15}$O relative states, the two lowest excited states have about 80% of $sd$-mixed components, and for the next two excited three-body states the proton-$^{15}$O relative s-states do not contribute. The spatial extension is as in ordinary nuclei. The widths of the resonances are estimated by the WKB transmission through the adiabatic potentials and found in agreement with the established experimental limits. We compare with experimental information and previous works.Comment: 29 pages, 7 postscript figures, to be published in Nuclear Physics

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

The LITAF/SIMPLE I92V sequence variant results in an earlier age of onset of CMT1A/HNPP diseases

Charcot-Marie-Tooth disease type 1A (CMT1A) and hereditary neuropathy with liability to pressure palsies (HNPP) represent the most common heritable neuromuscular disorders. Molecular diagnostics of CMT1A/HNPP diseases confirm clinical diagnosis, but their value is limited to the clinical course and prognosis. However, no biomarkers of CMT1A/HNPP have been identified. We decided to explore if the LITAF/SIMPLE gene shared a functional link to the PMP22 gene, whose duplication or deletion results in CMT1A and HNPP, respectively. By studying a large cohort of CMT1A/HNPP-affected patients, we found that the LITAF I92V sequence variant predisposes patients to an earlier age of onset of both the CMT1A and HNPP diseases. Using cell transfection experiments, we showed that the LITAF I92V sequence variant partially mislocalizes to the mitochondria in contrast to wild-type LITAF which localizes to the late endosome/lysosomes and is associated with a tendency for PMP22 to accumulate in the cells. Overall, this study shows that the I92V LITAF sequence variant would be a good candidate for a biomarker in the case of the CMT1A/HNPP disorders