The peculiarities of adaptive responses of cardiorespira-Tory system in changing gas environment in rowers with different lung ventilation levels

The compensatory mechanisms of moderate forms of hypoxia, hypercapnia or their combinations in a healthy body are of certain adaptive value in formation of adaptive responses, intended to increase body resistance to a whole set of extreme factors, and sports activity is not an exclusion. Any body changes influenced by extreme factors result in gas imbalance - hypoxia and hypercapnia. Thereby, training with breathing gaseous mixtures with different oxygen and carbon dioxide concentration can be used to increase the level of functionalities without increasing training loads. Herewith, the individual features of body's physiological responses influenced by various extreme factors, including hypoxia and hypercapnia, in view of the random level of lung ventilation. Hence, the purpose of the study was to consider adaptive responses of cardiorespiratory system in persons with different lung ventilation levels when breathing under conditions of combined hypoxia and hypercapnia. The individual-typological features of ensured adequate level of metabolism of the gas transport system in the ones with different initial lung ventilation levels included more efficient heart work in those with the initially low breathing index and higher O2 blood extraction in the persons with a high breathing index

Magnetic and spectral properties of multi-sublattice oxides SrY2O4:Er3+ and SrEr2O4

SrEr2O4 is a geometrically frustrated magnet which demonstrates rather unusual properties at low temperatures including a coexistence of long- and short-range magnetic order, characterized by two different propagation vectors. In the present work, the effects of crystal fields (CF) in this compound containing four magnetically inequivalent erbium sublattices are investigated experimentally and theoretically. We combine the measurements of the CF levels of the Er3+ ions made on a powder sample of SrEr2O4 using neutron spectroscopy with site-selective optical and electron paramagnetic resonance measurements performed on single crystal samples of the lightly Er-doped nonmagnetic analogue, SrY2O4. Two sets of CF parameters corresponding to the Er3+ ions at the crystallographically inequivalent lattice sites are derived which fit all the available experimental data well, including the magnetization and dc susceptibility data for both lightly doped and concentrated samples.Comment: 14 pages, 9 figure

Coupled Dynamics of Spin Qubits in Optical Dipole Microtraps: Application to the Error Analysis of a Rydberg-Blockade Gate

Single atoms in dipole microtraps or optical tweezers have recently become a promising platform for quantum computing and simulation. Here we report a detailed theoretical analysis of the physics underlying an implementation of a Rydberg two-qubit gate in such a system—a cornerstone protocol in quantum computing with single atoms. We focus on a blockade-type entangling gate and consider various decoherence processes limiting its performance in a real system. We provide numerical estimates for the limits on fidelity of the maximally entangled states and predict the full process matrix corresponding to the noisy two-qubit gate. We consider different excitation geometries and show certain advantages for the gate realization with linearly polarized driving beams. Our methods and results may find implementation in numerical models for simulation and optimization of neutral atom based quantum processors

Spontaneous ferromagnetic spin ordering at the surface of La2 Cu O4

Magnetic properties of high purity stoichiometric La2 Cu O4 nanoparticles are systematically investigated as a function of particle size. Ferromagnetic single-domain spin clusters are shown to spontaneously form at the surface of fine grains as well as paramagnetic defects. Hysteresis loops and thermomagnetic irreversibility are observed in a wide temperature range 5-350 K with the remnant moment and coercivity gradually decreasing with increasing temperature. Possible origins of the spontaneous surface ferromagnetic clusters and the relation of our data to the appearance of unusual magnetic phenomena and phase separation of doped cuprates are discussed. © 2007 The American Physical Society

Single-particle and collective mode couplings associated with 1- and 2-directional electronic ordering in metallic RTe3 (R = Ho, Dy, Tb)

The coupling of phonons with collective modes and single-particle gap excitations associated with one (1d) and two-directional (2d) electronically-driven charge-density wave (CDW) ordering in metallic RTe{sub 3} is investigated as a function of rare-earth ion chemical pressure (R = Tb, Dy, Ho) using femtosecond pump-probe spectroscopy. From the T-dependence of the CDW gap {Delta}{sub CDW} and the amplitude mode (AM) we find that while the transition to a 1d-CDW ordered state at Tc1 initially proceeds in an exemplary mean-field (MF)-like fashion, below T{sub c1}, {Delta}{sub CDW} is depressed and departs from the MF behavior. The effect is apparently triggered by resonant mode-mixing of the amplitude mode (AM) with a totally symmetric phonon at 1.75 THz. At low temperatures, when the state evolves into a 2d-CDW ordered state at T{sub c2} in the DyTe{sub 3} and HoTe{sub 3}, additional much weaker mode mixing is evident but no soft mode is observed

The transition from dynamics to statics in the electron-spin-resonance spectra of impurity Mn2+ ions in strontium titanate

The electron-spin-resonance (ESR) spectra of SrTiO3:Mn single crystals have been investigated. Results unambiguously indicate that the impurity center formed by an Mn2+ ion has a dynamic nature. In the high temperature range (T > 100 K), ESR spectra of Mn2+ ions reveal cubic symmetry; the spectrum is found to broaden significantly with a decrease in temperature. Upon cooling to T < 10 K, low-symmetry centers of Mn2+ ions with a strong orientational dependence emerge in the spectra. Temperature evolution of the ESR spectrum can be described within the model of a dynamic off-center Mn2+ ion substituting for the Sr 2+ ion, with a transition to the static regime at low temperatures with an average localization energy of ∼2.4 ± 0.4 meV for Mn 2+ centers due to random deformations. © 2014 Pleiades Publishing, Ltd

Seasonal changes in chlorophyll and carotenoid content in needles of scots pines (pinus sylvestris l.) Exposed to the thermal field of a gas flare

Seasonal changes in chlorophyll (Chl) and carotenoid (Car) content were analyzed in needle samples from young Scots pines (Pinus sylvestris L.) growing in the thermal field zone at various distances from the petroleum gas flare. Experiments were performed in Khanty Mansi Autonomous Area (Yugra) of Russia throughout the autumn–winter–spring period. Two hypotheses were subject to verification: (1) the thermal field of petroleum gas combustion flame imitates the influence of climate warming on plants, thus affecting the pigment complex of the photosynthetic apparatus (PSA) in pine needles; (2) transformations of PSA pigment complex in pine needles throughout the autumn–winter–spring period are sensitive to a long-term rise in ambient temperature by 1–2°С. In the winter period, the seasonal dynamics of certain PSA parameters comprised maxima and minima that are supposedly due to the regulation of Chl and Car content upon changes in air temperature. In trees growing under divergent thermal conditions, seasonal changes of these parameters were not synchronous. Analysis of seasonal changes revealed that winter-related transformations of the PSA structural–functional condition in needles are subject to consistent variations at different distances from the gas flame. The PSA activity of needles throughout the studied period was higher near the flame and decreased with the distance from the gas flare. When Chl content in needles decreased in autumn–winter, the smallest reduction was observed in the location near the gas flare (site I) where temperature was 1–2°C higher than the background level. The intermediate decrease in pigment content was noted at a moderate distance from the flame (site III), while the most pronounced decrease occurred at the largest distance from the gas flare (site VII). At the same time, the Chl a/b content ratio in needles was consistently lower for trees located at site I than at site VII. Hence, the amount of light-harvesting complexes in chloroplasts from trees grown at site I was higher than the amount of photosystems in the same chloroplasts. The Chl (a + b)/Car ratio in needles of trees grown near the gas flare (site I) was higher than in locations III and VII. This ratio displayed two significant peaks in the winter dynamics, which was supposedly due to the sufficient preservation of green pigments. Divergent seasonal changes in Chl and Car content and their dissimilar correlations with air temperature indicate that the pools of these pigments are controlled by different mechanisms. The actual Chl content, determined by the balance of pigment degradation and synthesis, should depend on the environmentally modified Chl synthesis and on the protective function of Car. Photosynthesizing cells produce additional amounts of carotenoids during autumn–winter, thus preventing the photodegradation of Chl in the period from autumn to late spring. © 2021, Pleiades Publishing, Ltd.This work was supported by the Comprehensive Program of the Ural Branch of the Russian Academy of Sciences for 2018–2020 (project no. 18-4-4-10) and by a state assignment to the Institute Botanic Garden of the Ural Branch of the Russian Academy of Sciences