Towards accelerated rates for distributed optimization over time-varying networks

We study the problem of decentralized optimization over time-varying networks with strongly convex smooth cost functions. In our approach, nodes run a multi-step gossip procedure after making each gradient update, thus ensuring approximate consensus at each iteration, while the outer loop is based on accelerated Nesterov scheme. The algorithm achieves precision $\varepsilon > 0$ in $O(\sqrt{\kappa_g}\chi\log^2(1/\varepsilon))$ communication steps and $O(\sqrt{\kappa_g}\log(1/\varepsilon))$ gradient computations at each node, where $\kappa_g$ is the global function number and $\chi$ characterizes connectivity of the communication network. In the case of a static network, $\chi = 1/\gamma$ where $\gamma$ denotes the normalized spectral gap of communication matrix $\mathbf{W}$. The complexity bound includes $\kappa_g$, which can be significantly better than the worst-case condition number among the nodes

EXTREME SUBCULTURES: THEORETICAL AND METHODOLOGICAL ASPECTS OF THE STUDY

Цель. Состоит в теоретическом анализе феномена экстремальности и социализирующей функции экстремальных субкультур в современном обществе.Методы и методология проведения работы. Использованы идеи социокультурного, интеракционистского, феноменологического и социопсихологического подходов.Результаты. Произведена конкретизация проблемы в контексте определения социокультурных оснований экстрима. Определено понятие экстремальной субкультуры в качестве единицы, простейшего системного образования, отвечающего за актуализацию и репрезентацию экстремальности на культурном и социальном уровне.Область применения результатов. Результаты исследования могут использоваться в научной и практической сфере, а также расширить научные знания о социокультурных основаниях и формах проявления экстрима в современном обществе.Purpose. It consists in the theoretical analysis of the phenomenon of extremality and the socializing function of extreme subcultures in modern society.Methodology. The ideas of sociocultural, interactionist, phenomenological and sociopsychological approaches are used.Results. The problem is concretized in the context of the definition of the sociocultural grounds of the extreme. The concept of an extreme subculture as a unit, the simplest systemic formation responsible for actualization and representation of extremism at the cultural and social level is defined.Practical implications. The results of the research can be used in the scientific and practical sphere, as well as to expand scientific knowledge about the sociocultural foundations and forms of manifestation of extreme in modern society

Stochastic beamforming for cochlear implant coding

Cochlear implants are prosthetic devices used to provide hearing to people who would otherwise be profoundly deaf. The deliberate addition of noise to the electrode signals could increase the amount of information transmitted, but standard cochlear implants do not replicate the noise characteristic of normal hearing because if noise is added in an uncontrolled manner with a limited number of electrodes then it will almost certainly lead to worse performance. Only if partially independent stochastic activity can be achieved in each nerve fibre can mechanisms like suprathreshold stochastic resonance be effective. We are investigating the use of stochastic beamforming to achieve greater independence. The strategy involves presenting each electrode with a linear combination of independent Gaussian noise sources. Because the cochlea is filled with conductive salt solutions, the noise currents from the electrodes interact and the effective stimulus for each nerve fibre will therefore be a different weighted sum of the noise sources. To some extent therefore, the effective stimulus for a nerve fibre will be independent of the effective stimulus of neighbouring fibres. For a particular patient, the electrode position and the amount of current spread are fixed. The objective is therefore to find the linear combination of noise sources that leads to the greatest independence between nerve discharges. In this theoretical study we show that it is possible to get one independent point of excitation (one null) for each electrode and that stochastic beamforming can greatly decrease the correlation between the noise exciting different regions of the cochlea. © 2007 Copyright SPIE - The International Society for Optical Engineering

Analysis of the fetal heart activity during pregnancy by bispectrum-based abdominal signal processing

Для виявлення серцевої діяльності плоду запропоновано методику оцінки спектру третього порядку, що називається методикою оцінки біспектру сигналу. Для виділення серцевої діяльності плоду пропонується новий клас інформаційних ознак, що оцінюється у вигляді фазово-зв'язаних внесків, які містяться в абдомінальних сигналах, зареєстрованих на материнській черевній поверхні. Експериментальна верифікація запропонованого підходу виконана для абдомінальних сигналів, записаних у реальних людей з вкладами завад. Вклади серцевої діяльності плоду, виділені у біспектральній площині шляхом обчислення оцінок амплітудного біспектру, вказують на фазовий зв'язок між деякими спектральними компонентами, що містяться в абдомінальних сигналах. Проведено аналіз абдомінальних сигналів за допомогою запропонованого методу для пацієнтів, у яких було виявлено гіпоксію плоду. Отримані результати демонструють ефективне придушення інтерференції, що забезпечується за допомогою стратегії обробки сигналів на основі біспектру, та можливість виявлення гіпоксії плоду на раніх стадіях.A method for extraction fetal ECG contribution from abdominal signals and finding information features for detection of fetal hypoxia by bispectrum-based signal processing has been proposed

Synthesis of Amphiphilic Copolymers of N-Vinyl-2-pyrrolidone and Allyl Glycidyl Ether for Co-Delivery of Doxorubicin and Paclitaxel

Co-delivery of chemotherapeutics in cancer treatment has been proven essential for overcoming multidrug resistance and improving the outcome of therapy. We report the synthesis of amphiphilic copolymers of N-vinyl-2-pyrrolidone and allyl glycidyl ether of various compositions and demonstrate that they can form nanoaggregates capable of simultaneous covalent immobilization of doxorubicin by the epoxy groups in the shell and hydrophobic-driven incorporation of paclitaxel into the core of nanoparticles. The structure of the obtained copolymers was characterized by (13)C NMR, IR, and MALDI spectroscopy, as well as adsorption at the water/toluene interface. A linear increase in the number-average molecular weight of amphiphilic copolymers and a decrease in the number-average diameter of macromolecular aggregates with an increase in the ratio N-vinyl-2-pyrrolidone/allyl glycidyl ether were observed. The assembled nanocarriers were characterized by DLS. The reported novel nanocarriers can be of interest for delivery and co-delivery of a wide range of pharmacological preparations and combined therapy for cancer and other deceases

Phenethylamine-derived new psychoactive substances 2C-E-FLY, 2C-EF-FLY, and 2C-T-7-FLY: Investigations on their metabolic fate including isoenzyme activities and their toxicological detectability in urine screenings

Psychoactive substances of the 2C-series are phenethylamine-based designer drugs that can induce psychostimulant and hallucinogenic effects. The so-called 2C-FLY series contains rigidified methoxy groups integrated in a 2,3,6,7-tetrahydrobenzo[1,2-b:4,5-b']difuran core. The aim of the presented work was to investigate the in vivo and in vitro metabolic fate including isoenzyme activities and toxicological detectability of the three new psychoactive substances (NPS) 2C-E-FLY, 2C-EF-FLY, and 2C-T-7-FLY to allow clinical and forensic toxicologists the identification of these novel compounds. Rat urine, after oral administration, and pooled human liver S9 fraction (pS9) incubations were analyzed by liquid chromatography-high-resolution tandem mass spectrometry (LC-HRMS/MS). By performing activity screenings, the human isoenzymes involved were identified and toxicological detectability in rat urine investigated using standard urine screening approaches (SUSAs) based on gas chromatography (GC)-MS, LC-MSn, and LC-HRMS/MS. In total, 32 metabolites were tentatively identified. Main metabolic steps consisted of hydroxylation and N acetylation. Phase I metabolic reactions were catalyzed by CYP2D6, 3A4, and FMO3 and N-acetylation by NAT1 and 2. Methoxyamine was used as a trapping agent for detection of the deaminated metabolite formed by MAO-A and B. Interindividual differences in the metabolism of the 2C-FLY drugs could be caused by polymorphisms of enzymes involved or drug-drug interactions. All three SUSAs were shown to be suitable to detect an intake of these NPS but common metabolites of 2C-E-FLY and 2C-EF-FLY have to be considered during interpretation of analytical findings

Multifractal characterization of stochastic resonance

We use a multifractal formalism to study the effect of stochastic resonance in a noisy bistable system driven by various input signals. To characterize the response of a stochastic bistable system we introduce a new measure based on the calculation of a singularity spectrum for a return time sequence. We use wavelet transform modulus maxima method for the singularity spectrum computations. It is shown that the degree of multifractality defined as a width of singularity spectrum can be successfully used as a measure of complexity both in the case of periodic and aperiodic (stochastic or chaotic) input signals. We show that in the case of periodic driving force singularity spectrum can change its structure qualitatively becoming monofractal in the regime of stochastic synchronization. This fact allows us to consider the degree of multifractality as a new measure of stochastic synchronization also. Moreover, our calculations have shown that the effect of stochastic resonance can be catched by this measure even from a very short return time sequence. We use also the proposed approach to characterize the noise-enhanced dynamics of a coupled stochastic neurons model.Comment: 10 pages, 21 EPS-figures, RevTe