Transition from chimera/solitary states to traveling waves

We study numerically the spatiotemporal dynamics of a ring network of nonlocally coupled nonlinear oscillators, each represented by a two-dimensional discrete-time model of the classical van der Pol oscillator. It is shown that the discretized oscillator exhibits a richer behavior, combining the peculiarities of both the original system and its own dynamics. Moreover, a large variety of spatiotemporal structures is observed in the network of discrete van der Pol oscillators when the discretization parameter and the coupling strength are varied. Such regimes as the coexistence of multichimera state/traveling wave and solitary state are revealed for the first time and studied in detail. It is established that the majority of the observed chimera/solitary states, including the newly found ones, are transient towards the purely traveling wave mode. The peculiarities of the transition process and the lifetime (transient duration) of the chimera structures and the solitary state are analyzed depending on the system parameters, observation time, initial conditions, and influence of external noise

Effectiveness evaluation of implementation of target programs for municipal education: improvement of approaches

The paper is devoted to the study of the problem of effective quality evaluation of the implementation of municipal target programs in the regions of the Russian Federation. The evaluation of target programs is a methodologically complex process that requires not only specific knowledge, but also well-formed tools (approaches for effectiveness assessment). The authors revealed that there is no all-purpose approach to assess the effectiveness of municipal target programs in municipalities of the Russian Federation. However, municipalities develop different criteria and scales to evaluate the effectiveness of different programs. It is determined that the assessment is mainly based on two indicators, namely, the social outcome and budget efficiency resulting from the assessment of achievement of the planned targets of indicators. The authors emphasize the importance to interconnect the indicators of target programs’ implementation and strategic industry based plans. The method of integral assessment of program effectiveness is developed to make it possible to evaluate the implementation of programs at each stage to compare the results with the planned ones and to record critical moments that affect the effectiveness of program implementation to use tools to eliminate or minimize the impact of the risk events

The role of coupling, noise and harmonic impact in oscillatory activity of an excitable FitzHugh–Nagumo oscillator network

Background and Objectives: The dynamics of a separate small ensemble and coupled small ensembles of excitable FitzHugh–Nagumo oscillators is studied. Different topologies and types of coupling between elements, as well as external noise and harmonic impact are considered. Models and Methods: The main model is a ring of five locally coupled excitable FitzHugh–Nagumo neurons, into which additional connections and external disturbances are introduced. Also, two such systems are connected via a hub, represented by a single FitzHugh–Nagumo neuron. To assess the influence of various system parameters on the neuronal spike activity, maps of the average firing frequency are constructed in the plane of control parameters, and the critical values of the parameters necessary for the occurrence of spikes are found. Results: It has been shown that a repulsive local coupling can excite spike activity in a network of excitable oscillators without external impact, and the addition of remote coupling expands the range of parameters in which firings are observed. Besides, by introducing anomalous Lévy noise, it is possible to excite oscillations in the system at lower values of the coupling strength between neurons than by utilising normal Gaussian noise. Also, in a system of two ensembles of neurons connected through a common hub, the interlayer coupling leads not only to synchronisation of the firing frequencies of these ensembles, but also to a transition to the spike activity mode even when no firing was observed in individual ensembles. By changing the parameters of the external harmonic impact and the coupling coefficients of the two ensembles with a common hub, it is possible to influence the average firing frequency

Effects of Spiro-Cyclohexane Substitution of Nitroxyl Biradicals on Dynamic Nuclear Polarization

Spiro-substituted nitroxyl biradicals are widely used as reagents for dynamic nuclear polarization (DNP), which is especially important for biopolymer research. The main criterion for their applicability as polarizing agents is the value of the spin–spin exchange interaction parameter (J), which can vary considerably when different couplers are employed that link the radical moieties. This paper describes a study on biradicals, with a ferrocene-1,1′-diyl-substituted 1,3-diazetidine-2,4-diimine coupler, that have never been used before as DNP agents. We observed a substantial difference in the temperature dependence between Electron Paramagnetic Resonance (EPR) spectra of biradicals carrying either methyl or spirocyclohexane substituents and explain the difference using Density Functional Theory (DFT) calculation results. It was shown that the replacement of methyl groups by spirocycles near the N-O group leads to an increase in the contribution of conformers having J ≈ 0. The DNP gain observed for the biradicals with methyl substituents is three times higher than that for the spiro-substituted nitroxyl biradicals and is inversely proportional to the contribution of biradicals manifesting the negligible exchange interaction. The effects of nucleophiles and substituents in the nitroxide biradicals on the ring-opening reaction of 1,3-diazetidine and the influence of the ring opening on the exchange interaction were also investigated. It was found that in contrast to the methyl-substituted nitroxide biradical (where we observed the ring-opening reaction upon the addition of amines), the ring opening does not occur in the spiro-substituted biradical owing to a steric barrier created by the bulky cyclohexyl substituents

Specialiosios paskirties savivaldybių programų įgyvendinimo efektyvumo vertinimas: metodų tobulinimas

The paper is devoted to the study of the problem of effective quality evaluation of the implementation of municipal target programs in the regions of the Russian Federation. The evaluation of target programs is a methodologically complex process that requires not only specific knowledge, but also well-formed tools (approaches for effectiveness assessment). The authors revealed that there is no all-purpose approach to assess the effectiveness of municipal target programs in municipalities of the Russian Federation. However, municipalities develop different criteria and scales to evaluate the effectiveness of different programs. It is determined that the assessment is mainly based on two indicators, namely, the social outcome and budget efficiency resulting from the assessment of achievement of the planned targets of indicators. The authors emphasize the importance to interconnect the indicators of target programs’ implementation and strategic industrybased plans. The method of integral assessment of program effectiveness is developed to make it possible to evaluate the implementation of programs at each stage to compare the results with the planned ones and to record critical moments that affect the effectiveness of program implementation to use tools to eliminate or minimize the impact of the risk events.Straipsnyje nagrinėjamas specialios paskirties savivaldybių programų įgyvendinimo efektyvumas Rusijos Federacijos regionuose. Specialiosios paskirties programų vertinimas yra metodiškai sudėtingas procesas, reikalaujantis ne tik specialių žinių, bet ir parengtų priemonių (efektyvumo vertinimo metodikos). Autoriai atskleidė, kad Rusijos Federacijos savivaldybių struktūrose nėra universalių metodų, skirtų specialios paskirties savivaldybių programų efektyvumui vertinti; savivaldybių struktūros kuria įvairius kriterijus ir vertinimo skales, kad įvertintų įvairių programų efektyvumą. Nustatyta, kad vertinimas daugiausia grindžiamas dviem rodikliais - socialiniu poveikiu ir biudžeto efektyvumu, kurių pagrindas – rodiklių planinių tikslinių verčių pasiekimo įvertinimas. Autoriai įrodė būtinybę integruoti specialiosios paskirties programų įgyvendinimo rodiklius su strateginiais sektorių planais. Jie taip pat pasiūlė integruoto programų efektyvumo vertinimo metodus, kurie leidžia įvertinti kiekvieną programų įgyvendinimo etapą, lyginant gautus rezultatus su planuojamais rezultatais; registruoti kritines problemas, turinčias įtakos įgyvendinimo efektyvumui ir taikyti priemones, skirtas rizikos pasekmėms kuo labiau sumažinti

Transition from complete synchronization to spatio-temporal chaos in coupled chaotic systems with nonhyperbolic and hyperbolic attractors

We study the transition from coherence (complete synchronization) to incoherence (spatio-temporal chaos) in ensembles of nonlocally coupled chaotic maps with nonhyperbolic and hyperbolic attractors. As basic models of a partial element we use the Henon map and the Lozi map. We show that the transition to incoherence in a ring of coupled Henon maps occurs through the appearance of phase and amplitude chimera states. An ensemble of coupled Lozi maps demonstrates the coherence-incoherence transition via solitary states and no chimera states are observed in this case

Aromatic SNF-Approach to Fluorinated Phenyl tert-Butyl Nitroxides

The interaction of octafluorotoluene (1a), as well as pentafluorobenzonitrile (1b) with tert-butylamine, followed by the oxidation of thus formed tert-butylanilines (2a,b) with meta-chloroperoxybenzoic acid led to functionalized perfluorinated phenyl tert-butyl nitroxides [namely, 4-(N-tert-butyl(oxyl)amino)heptafluorotoluene (3a) and 4-(N-tert-butyl(oxyl)amino)tetrafluorobenzonitrile (3b)] with nearly quantitative total yields. The molecular and crystal structures of nitroxide 3a were proved by single crystal X-ray diffraction analysis. The radical nature of both nitroxides was confirmed by ESR data. The interaction of Cu(hfac)2 with the obtained nitroxides 3a,b gave corresponding trans-bis(1,1,1,5,5,5-hexafluoropentane-2,4-dionato-κ2O,O′)bis{4-(N-tert-butyl(oxyl)amino)perfluoroarene-κO}copper (II) complexes ([Cu(hfac)2(3a)2] and [Cu(hfac)2(3b)2]). X-ray crystal structure analysis showed square bipyramid coordination of a centrally symmetric Cu polyhedron with the axial positions occupied by oxygen atoms of the nitroxide groups. Magnetic measurements revealed intramolecular ferromagnetic exchange interactions between unpaired electrons of Cu(II) ions and paramagnetic ligands, with exchange interaction parameters JCu–R reaching 53 cm−1

2-Butyl-2-tert-butyl-5,5-diethylpyrrolidine-1-oxyls: Synthesis and Properties

Nitroxides are broadly used as molecular probes and labels in biophysics, structural biology, and biomedical research. Resistance of a nitroxide group bearing an unpaired electron to chemical reduction with low-molecular-weight antioxidants and enzymatic systems is of critical importance for these applications. The redox properties of nitroxides are known to depend on the ring size (for cyclic nitroxides) and electronic and steric effects of the substituents. Here, two highly strained nitroxides, 5-(tert-butyl)-5-butyl-2,2-diethyl-3-hydroxypyrrolidin-1-oxyl (4) and 2-(tert-butyl)-2-butyl-5,5-diethyl-3,4-bis(hydroxymethyl)pyrrolidin-1-oxyl (5), were prepared via a reaction of the corresponding 2-tert-butyl-1-pyrroline 1-oxides with butyllithium. Thermal stability and kinetics of reduction of the new nitroxides by ascorbic acid were studied. Nitroxide 5 showed the highest resistance to reduction

Calcium Chelidonate: Semi-Synthesis, Crystallography, and Osteoinductive Activity In Vitro and In Vivo

Calcium chelidonate [Ca(ChA)(H2O)3]n was obtained by semi-synthesis using natural chelidonic acid. The structure of the molecular complex was determined by X-ray diffraction analysis. The asymmetric unit of [Ca(ChA)(H2O)3]n includes chelidonic acid coordinated through three oxygen atoms, and three water ligands. The oxygen atoms of acid and oxygen atoms of water from each asymmetric unit are also coordinated to the calcium of another one, forming an infinite linear complex. Calcium geometry is close to the trigonal dodecahedron (D2d). The intra-complex hydrogen bonds additionally stabilize the linear species, which are parallel to the axis. In turn the linear species are packed into the 3D structure through mutual intercomplex hydrogen bonds. The osteogenic activity of the semi-synthetic CaChA was studied in vitro on 21-day hAMMSC culture and in vivo in mice using ectopic (subcutaneous) implantation of CaP-coated Ti plates saturated in vitro with syngeneic bone marrow. The enhanced extracellular matrix ECM mineralization in vitro and ectopic bone tissue formation in situ occurred while a water solution of calcium chelidonate at a dose of 10 mg/kg was used. The test substance promotes human adipose-derived multipotent mesenchymal stromal/stem cells (hAMMSCs), as well as mouse MSCs to differentiate into osteoblasts in vitro and in vivo, respectively. Calcium chelidonate is non-toxic and can stimulate osteoinductive processes