Short-Baseline Active-Sterile Neutrino Oscillations?

We suggest the possibility that the anomalies observed in the LSND experiment and the Gallium radioactive source experiments may be due to neutrino oscillations generated by a large squared-mass difference of about 20 - 30 eV^2. We consider the simplest 3+1 four-neutrino scheme that can accommodate also the observed solar and atmospheric neutrino oscillations. We show that, in this framework, the disappearance of nu_e and nu_mu in short-baseline neutrino oscillation experiments is mainly due to active-sterile transitions. The implications of the first MiniBooNE results, appeared after the completion of this paper, are discussed in an addendum.Comment: 12 pages. The implications of the first MiniBooNE results are discussed in an addendu

Enhancement of superconductivity in NbN nanowires by negative electron-beam lithography with positive resist

We performed comparative experimental investigation of superconducting NbN nanowires which were prepared by means of positive-and negative electron-beam lithography with the same positive tone Poly-methyl-methacrylate (PMMA) resist. We show that nanowires with a thickness 4.9 nm and widths less than 100 nm demonstrate at 4.2 K higher critical temperature and higher density of critical and retrapping currents when they are prepared by negative lithography. Also the ratio of the experimental critical-current to the depairing critical current is larger for nanowires prepared by negative lithography. We associate the observed enhancement of superconducting properties with the difference in the degree of damage that nanowire edges sustain in the lithographic process. A whole range of advantages which is offered by the negative lithography with positive PMMA resist ensures high potential of this technology for improving performance metrics of superconducting nanowire singe-photon detectors

Towards single-electron metrology

We review the status of the understanding of single-electron transport (SET) devices with respect to their applicability in metrology. Their envisioned role as the basis of a high-precision electrical standard is outlined and is discussed in the context of other standards. The operation principles of single electron transistors, turnstiles and pumps are explained and the fundamental limits of these devices are discussed in detail. We describe the various physical mechanisms that influence the device uncertainty and review the analytical and numerical methods needed to calculate the intrinsic uncertainty and to optimise the fabrication and operation parameters. Recent experimental results are evaluated and compared with theoretical predictions. Although there are discrepancies between theory and experiments, the intrinsic uncertainty is already small enough to start preparing for the first SET-based metrological applications.Comment: 39 pages, 14 figures. Review paper to be published in International Journal of Modern Physics

SYNTHESIS OF MODIFIED PECTIN AND FURTHER DEVELOPMENT TO FORM MICRO-GEL PARTICLES USING 1,4-BIS(3-AMINOPROPYL)PIPERAZINE

The experiment was made to attach amino ligands to pectin molecules while overcoming the problem of hydrolysis of pectin in water. After the successful synthesis, the modified pectin was cross-linked into micro-gel particles for further uses

Dynamics of the magnetic flux trapped in fractal clusters of normal phase in a superconductor

The influence of geometry and morphology of superconducting structure on critical currents and magnetic flux trapping in percolative type-II superconductor is considered. The superconductor contains the clusters of a normal phase, which act as pinning centers. It is found that such clusters have significant fractal properties. The main features of these clusters are studied in detail: the cluster statistics is analyzed; the fractal dimension of their boundary is estimated; the distribution of critical currents is obtained, and its peculiarities are explored. It is examined thoroughly how the finite resolution capacity of the cluster geometrical size measurement affects the estimated value of fractal dimension. The effect of fractal properties of the normal phase clusters on the electric field arising from magnetic flux motion is investigated in the case of an exponential distribution of cluster areas. The voltage-current characteristics of superconductors in the resistive state for an arbitrary fractal dimension are obtained. It is revealed that the fractality of the boundaries of the normal phase clusters intensifies the magnetic flux trapping and thereby raises the critical current of a superconductor.Comment: revtex, 16 pages with 1 table and 5 figures; text and figures are improved; more detailed version with geometric probability analisys of the distribution of entry points into weak links over the perimeter of a normal phase clusters and one additional figure is published in Phys.Rev.B; alternative e-mail of author is [email protected]

Relief and geology of the north polar region of the planet Venus

Description of topographic features is given for the North polar region of the planet Venus. Principal geomorphic types of terrain are characterized as well as their geologic relations. Relative ages of geologic units in Venus North polar region are discussed

Polycystic ovary syndrome and periodontal status: a literature review

The review considers the problem of connection the polycystic ovarian syndrome and periodontal disorders of the fertile women. The authors marked that this problem is not virtually touched upon in Russian science. In the foreign literature this issue is discussed in connection with studying the micro-biome and oxidative stress. The authors refer to some articles showing that the quantity of pathogenic microorganisms responsible for periodontal disorders and the level of specific antibodies in blood serum are increased in women with polycystic ovarian syndrome, especially in the cases of gum inflammation. Also the article gives the data where the results show the wider spreading of periodontal disorders in women with polycystic ovarian syndrome in comparison with the healthy ones where controls were matched by age and BMI. The authors think that studies on oral microbiocenose disorders and tissue quality of periodontium of the fertile women with polycystic ovarian syndrome are quite important. The further studying of connection of polycystic ovarian syndrome and oral mucous membrane inflammation could reveal definite periodontal pathogens, which can influence systematic inflammation processes in polycystic ovarian syndrome

Sulfonated octa-substituted Co(II) phthalocyanines immobilized on silica matrix as catalyst for Thiuram E synthesis

© 2018 John Wiley & Sons, Ltd. Silica nanoparticles were obtained during the work according to two different sol–gel methods. In first one Schtrober's technique and series of cobalt phthalocyanine metal complexes varying in peripheral substituents were used. Second method was performed using the same complexes but differed in applying surface-active substance (SAS) and two precursors – tetraethoxysilane (TEOS) and aminopropyltrimethoxysilane (APTMOS). All obtained hybrid materials were analyzed via SEM, the size of single particle was studied, which in all cases was about 200 nm. In order to investigate hybrid's characteristics laser diffraction and liquid nitrogen adsorption methods were applied. Distinction in pore's specific volume of differently-obtained nanoparticles was found. Catalytic activity of all obtained materials were tested in conversion of N,N-diethylcarbamodithiolate to thiuram E. Effect of peripherally substituted phthalocyanines and morphology of matrixes were manifested on catalytic activity of the hybrids