Time-delayed feedback control of coherence resonance near subcritical Hopf bifurcation: theory versus experiment

Using the model of a generalized Van der Pol oscillator in the regime of subcritical Hopf bifurcation we investigate the influence of time delay on noise-induced oscillations. It is shown that for appropriate choices of time delay either suppression or enhancement of coherence resonance can de achieved. Analytical calculations are combined with numerical simulations and experiments on an electronic circuit

Spin-transfer mechanism of ferromagnetism in polymerized fullerenes: AbinitioAb initio calculations

A mechanism of the high temperature ferromagnetism in polymerized fullerenes is suggested. It is assumed that some of the C$_{60}$ molecules in the crystal become magnetically active due to spin and charge transfer from the paramagnetic impurities (atoms or groups), such as hydrogen, fluorine, hydroxyl group OH, amino group NH$_2$, or methyl group CH$_3$, dispersed in the fullerene matrix. The exchange interaction between the spins localized on the magnetically active fullerenes is evaluated using \textit{ab initio} calculations. The nearest neighbour and next nearest neighbour exchange interaction is found to be in the range $0.1\div 0.3$ eV, that is, high enough to account for the room temperature ferromagnetism.Comment: typos corrected, 8 pages, 3 figures, LaTe

Coherence resonance in a network of FitzHugh-Nagumo systems: interplay of noise, time-delay and topology

We systematically investigate the phenomena of coherence resonance in time-delay coupled networks of FitzHugh-Nagumo elements in the excitable regime. Using numerical simulations, we examine the interplay of noise, time-delayed coupling and network topology in the generation of coherence resonance. In the deterministic case, we show that the delay-induced dynamics is independent of the number of nearest neighbors and the system size. In the presence of noise, we demonstrate the possibility of controlling coherence resonance by varying the time-delay and the number of nearest neighbors. For a locally coupled ring, we show that the time-delay weakens coherence resonance. For nonlocal coupling with appropriate time-delays, both enhancement and weakening of coherence resonance are possible

Oswald Schmiedeberg - the "father" of experimental pharmacology

Oswald Schmiedeberg (1838-1921) was a son of a bailiff and a maid of honour, the eldest of the six children in the family. He was born and educated in the Russian Empire. Scientific activity. All his life he was completely devoted to science, making experimental pharmacology an independent scientific discipline, and was able to bring it to the international level. O. Schmiedeberg studied the action of muscarine and nicotine, digitoxin, hypnotics and analeptics. He was the first to introduce the concept of - pharmacodynamics‖ and - pharmacokinetics‖ of a drug. With his participation, the world‘s first pharmacological journal was founded, which is still published toda

New Advantageous Method for the Production of Purified Cholera Toxin B-Subunit and Monoclonal Antibodies to It

Put forward is an efficient method for manufacturing cholera toxin B-subunit. Its advantages are relative simplicity and economy feasibility, as well as maximum output of the purified B-subunit, absolutely free from toxic A-subunit contaminant. All this is due to the deployment of cholera vibrio recombinant strain producing only cholera toxin B-subunit instead of cholera toxin as it is, which results in lack of residual preparation toxicity. Applied has been gel-penetration column chromatography, providing for stable native state and maximum antigen output. The method under discussion is verified experimentally. Sample purity has been analyzed after each phase of chromatographic investigation on TSK gel HW-60, using disc electrophoresis. It is established that three steps of purification are ample for the obtainment of cholera toxin B-subunit preparation free from admixtures. Immunological activity of the purified B-subunit is validated by monoclonal antibody obtainment. Designed preparation of cholera toxin B-subunit and monoclonal antibodies to it can serve as a basis for the development of various immune-diagnostic test-systems alternatives

New Insights on Rift Basin Development and the Geological Carbon Cycle, Mass Extinction, and Carbon Sequestration...

Field trip guide to northern Newark basin of New York and New Jersey including information on stratigraphic and tectonic framework based on outcrops, cores, drill holes and seismic lines

Jean Pecquet (1622–1674). To the 400th anniversary of the birth

The article is dedicated to the 400th anniversary of the birth of the outstanding French anatomist, physician and philosopher Jean Pecquet (1622–1674). Pecquet’s biography is connected with the city of Dieppe, where the future scientist was born and got his primary education, and with Paris, where he made his main discoveries in anatomy. Throughout his life, Pecquet collaborated with many prominent scientists of that time (Jacques Mentel, Louis Gayant, Jean Riolan (the Younger)), including not only physicians and anatomists, but also physicists such as Blaise Pascal, Edme Mariotte, Marin Mersenne and Evangelista Torricelli. Pecquet’s most famous discovery is the chyle cictern, or cisterna chyli. The structure was named after of the scientist – “Pecquet’s reservoir (cistern)”. But more revolutionary discovery made by Pecquet is revealing and proving the fact that the lymphatic ducts flow into the superior vena cava indirectly through the venous angles and refuting the conventional opinion on the drainage of lymph into the liver. An important help in Pecquet’s anatomical research and experiments was his passion for the physical and mathematical sciences. In collaboration with Edme Marriott, Pecquet studied the structure of the eyeball and turned out to be more foresighted, because, unlike Marriott, he correctly understood the role of the retina in the functioning of the eye as an organ of vision. Pecquet was one of William Harvey’s supporters regarding his concept of blood circulation. He introduced cutting-edge at that moment technologies into the anatomy methodology, including animal experiments in vivo, and made a fateful contribution to the progress of anatomical science

Differentiated approach to correcting low vitamin D status in adolescent girls in Moscow

Introduction. The work is devoted to the study of vitamin D status in adolescent girls and the selection of adequate doses for its correction.Study objective. To study the dynamics of calcidiol concentration in the blood serum against vitamin D3 intake and evaluate the effectiveness of correcting doses of vitamin in adolescent girls from Moscow.Study design. A double-blind, placebo-controlled, prospective, randomized clinical study.Materials and methods. The study involved adolescent girls aged from 11 to 17 years (n = 218) from I-II health groups, with determined serum level of 25(OH)D. Participants were randomly assigned to the main and control groups. The adolescent girls in the study group received vitamin D3 tablets, and the control group received a placebo. Study duration was 6 months. The dose of vitamin D3 was dependent on baseline serum caLcidioL levels and ranged from 800 IU to 2000 IU. Vitamin D status was redetermined in the girls who completed the treatment (n = 192).Results. Initially, 96.4% of girls had a low vitamin D status, while vitamin D insufficiency was observed in 26.6%, deficiency in 57.8%, deep deficiency in 12%. The median level of 25(OH)D in the main group before taking the vitamin was 16.25 ng/ml, after taking - 24.1            ng/ml, in the control group - 17.9 and 11.4 ng/ml, respectively (p < 0.001). In the main group, an increase in the content of the metabolite was observed in 94.9% of the subjects, the initially identified pronounced deficit was completely absent.Conclusions. A differentiated approach to prescribing different doses of cholecalciferon, depending on the baseline level of 25(OH)D, BMI and age, is an effective method for replenishing vitamin D deficiency in adolescents. The high probability of normalization of vitamin D status in certain age groups, mainly with the appointment of low corrective doses of cholecalciferol justifies the possibility of their use for 6 months or more in adolescents during puberty period