Suppression of timing errors in short overdamped Josephson junctions

The influence of fluctuations and periodical driving on temporal characteristics of short overdamped Josephson junction is analyzed. We obtain the standard deviation of the switching time in the presence of a dichotomous driving force for arbitrary noise intensity and in the frequency range of practical interest. For sinusoidal driving the resonant activation effect has been observed. The mean switching time and its standard deviation have a minimum as a function of driving frequency. As a consequence the optimization of the system for fast operation will simultaneously lead to minimization of timing errors.Comment: 4 pages, 4 figures, in press in Physical Review Letter

P2X1 and P2X5 subunits form the functional P2X receptor in mouse cortical astrocytes

ATP plays an important role in signal transduction between neuronal and glial circuits and within glial networks. Here we describe currents activated by ATP in astrocytes acutely isolated from cortical brain slices by non-enzymatic mechanical dissociation. Brain slices were prepared from transgenic mice that express enhanced green fluorescent protein under the control of the human glial fibrillary acidic protein promoter. Astrocytes were studied by whole-cell voltage clamp. Exogenous ATP evoked inward currents in 75 of 81 astrocytes. In the majority (~65%) of cells, ATP-induced responses comprising a fast and delayed component; in the remaining subpopulation of astrocytes, ATP triggered a smoother response with rapid peak and slowly decaying plateau phase. The fast component of the response was sensitive to low concentrations of ATP (with EC50 of ~40 nM). All ATP-induced currents were blocked by pyridoxal-phosphate-6-azophenyl-2',4'-disulfonate (PPADS); they were insensitive to ivermectin. Quantitative real-time PCR demonstrated strong expression of P2X1 and P2X5 receptor subunits and some expression of P2X2 subunit mRNAs. The main properties of the ATP-induced response in cortical astrocytes (high sensitivity to ATP, biphasic kinetics, and sensitivity to PPADS) were very similar to those reported for P2X1/5 heteromeric receptors studied previously in heterologous expression systems

Symmetrical Josephson vortex interferometer as an advanced ballistic single-shot detector

We consider a ballistic detector formed in an interferometer manner which operational principle relies on Josephson vortex scattering at a measurement potential. We propose an approach to symmetrize the detector scheme and explore arising advantages in the signal-to-noise ratio and in the back-action on a measured object by means of recently presented numerical and analytical methods for modeling of a soliton scattering dynamics in the presence of thermal fluctuations. The obtained characteristics for experimentally relevant parameters reveal practical applicability of the considered schemes including possibility of coupling with standard digital rapid single flux quantum circuits

Effect of Cherenkov radiation on the jitter of solitons in the driven underdamped Frenkel-Kontorova model

The effect of complex dynamics of solitons on the output noise of the system (thermal jitter) is studied in the frame of the driven underdamped Frenkel-Kontorova model. In contrast to the continuous case, we have observed a dramatic splash of the jitter. It is demonstrated that this jitter increase is related to the joining of an initial soliton with the one generated by large amplitude oscillations of the Cherenkov radiation tail, which results in the establishment of a unified soliton structure

Structure and vibrational spectra of carbon clusters in SiC

The electronic, structural and vibrational properties of small carbon interstitial and antisite clusters are investigated by ab initio methods in 3C and 4H-SiC. The defects possess sizable dissociation energies and may be formed via condensation of carbon interstitials, e.g. generated in the course of ion implantation. All considered defect complexes possess localized vibrational modes (LVM's) well above the SiC bulk phonon spectrum. In particular, the compact antisite clusters exhibit high-frequency LVM's up to 250meV. The isotope shifts resulting from a_{13}C enrichment are analyzed. In the light of these results, the photoluminescence centers D_{II} and P-U are discussed. The dicarbon antisite is identified as a plausible key ingredient of the D_{II}-center, whereas the carbon split-interstitial is a likely origin of the P-T centers. The comparison of the calculated and observed high-frequency modes suggests that the U-center is also a carbon-antisite based defect.Comment: 15 pages, 6 figures, accepted by Phys. Rev.

TECHNOLOGICAL SCHEMES FOR THE PROCESSES OF PREPARATION AND MILLING BINARY GRAIN MIXTURES AND BIOCHEMICAL EVALUATION OF PRODUCED PRODUCTS

A study of the preparation and milling of a grain mixture containing 7% of flax seeds has been carried out in order to obtain a composite wheat-flax flour, in which the entire biopotential of flax seeds was preserved. It was revealed that the preparation of the components of the grain mixture should be carried out independently, in parallel flows. During the wheat grain preparation the cold conditioning was carried out, the modes of which were the following: humidity — 15.5%, dwell time in the water — 24 hours. The optimal conditions for milling the wheat-flax mixture have been determined, which are the following: yield (%) / ash content (%) in 3 break systems (in terms of the 1st break system — grain) for the first break system — 53.5 / 1.00; for the second break system. — 22.2 / 1.11; totally for the first and the second break systems — 75.7 / 1.035; totally for the first, the second and the third break systems — 81.0 / 1.1. The technological schemes have been developed and the new varieties of wheat-flax flour with predetermined technological properties and increased nutritional value have been formed. The approximate indices of yield and quality of the new wheat-flax flour varieties are the following: Flour A — yield 45–50%, lipids 3.6–4.0%, protein 13–13.5%, ash 0.55–0.70%, whiteness — 50 conventional units; Flour B — yield 20–25%, lipids 5.5–6.0%, protein 14–14.5%, ash 0.9–1.25%, whiteness — 22 conventional units; Flour C — yield 70–75%, lipids 4.5–5.0%, protein 13.6–14.0%, ash 0.75–0.90%, whiteness — 36 conventional units. It was indicated that the total lipids content in flour from two-component mixtures increases by about 4 times, and the total protein content in the studied samples increases by 1–2%. The content of linoleic acid (ɷ‑6) in wheat-flax flour samples is 1.6…3.3 times higher than in wheat flour; the content of linolenic acid (ɷ‑3) in wheat-flax flour samples is 36.8…57.2 times higher than in wheat flour (taking into account the total lipids content in the samples). The enrichment of wheat flour due to flax seeds allows to make up the deficiency of PUFA family in the diet of a modern person and to obtain products on a grain basis of a balanced composition

Phi-Functions for 2D Objects Formed by Line Segments and Circular Arcs

We study the cutting and packing (C&P) problems in two dimensions by using phi-functions. Our phi-functions describe the layout of given objects; they allow us to construct a mathematical model in which C&P problems become constrained optimization problems. Here we define (for the first time) a complete class of basic phi-functions which allow us to derive phi-functions for all 2D objects that are formed by linear segments and circular arcs. Our phi-functions support translations and rotations of objects. In order to deal with restrictions on minimal or maximal distances between objects, we also propose adjusted phi-functions. Our phi-functions are expressed by simple linear and quadratic formulas without radicals. The use of radical-free phi-functions allows us to increase efficiency of optimization algorithms. We include several model examples